Human sperm pattern of movement during chemotactic re-orientation towards a progesterone source

PubMed Central

Blengini, Cecilia Soledad; Teves, Maria Eugenia; Uñates, Diego Rafael; Guidobaldi, Héctor Alejandro; Gatica, Laura Virginia; Giojalas, Laura Cecilia

2011-01-01

Human spermatozoa may chemotactically find out the egg by following an increasing gradient of attractant molecules. Although human spermatozoa have been observed to show several of the physiological characteristics of chemotaxis, the chemotactic pattern of movement has not been easy to describe. However, it is apparent that chemotactic cells may be identified while returning to the attractant source. This study characterizes the pattern of movement of human spermatozoa during chemotactic re-orientation towards a progesterone source, which is a physiological attractant candidate. By means of videomicroscopy and image analysis, a chemotactic pattern of movement was identified as the spermatozoon returned towards the source of a chemotactic concentration of progesterone (10 pmol l−1). First, as a continuation of its original path, the spermatozoon swims away from the progesterone source with linear movement and then turns back with a transitional movement that can be characterized by an increased velocity and decreased linearity. This sperm behaviour may help the spermatozoon to re-orient itself towards a progesterone source and may be used to identify the few cells that are undergoing chemotaxis at a given time. PMID:21765441

Chemotactic Motility of Sperm in Shear

NASA Astrophysics Data System (ADS)

Guasto, Jeffrey S.; Riffell, Jeffrey A.; Zimmer, Richard K.; Stocker, Roman

2011-11-01

Chemical gradients are utilized by plants and animals in sexual reproduction to guide swimming sperm cells toward the egg. This process (``chemotaxis''), which can greatly increase the success of fertilization, is subject to interference by fluid flow, both in the bodily conduits of internal fertilizers (e.g. mammals) and in the aquatic environment of external fertilizers (e.g. benthic invertebrates). We studied the biomechanics of chemotaxing sea urchin spermatozoa using microfluidic devices, which allow for the precise and independent control of attractant gradients and fluid shear. We captured swimming trajectories and flagellar beat patterns using high-speed video-microscopy, to detect chemotactic responses and measure the effect of fluid forces on swimming. This work will ultimately help us to understand how swimming sperm cells actively navigate natural chemoattractant gradients for successful fertilization.

About Small Streams and Shiny Rocks: Macromolecular Crystal Growth in Microfluidics

NASA Technical Reports Server (NTRS)

vanderWoerd, Mark; Ferree, Darren; Spearing, Scott; Monaco, Lisa; Molho, Josh; Spaid, Michael; Brasseur, Mike; Curreri, Peter A. (Technical Monitor)

2002-01-01

We are developing a novel technique with which we have grown diffraction quality protein crystals in very small volumes, utilizing chip-based, microfluidic ("LabChip") technology. With this technology volumes smaller than achievable with any laboratory pipette can be dispensed with high accuracy. We have performed a feasibility study in which we crystallized several proteins with the aid of a LabChip device. The protein crystals are of excellent quality as shown by X-ray diffraction. The advantages of this new technology include improved accuracy of dispensing for small volumes, complete mixing of solution constituents without bubble formation, highly repeatable recipe and growth condition replication, and easy automation of the method. We have designed a first LabChip device specifically for protein crystallization in batch mode and can reliably dispense and mix from a range of solution constituents. We are currently testing this design. Upon completion additional crystallization techniques, such as vapor diffusion and liquid-liquid diffusion will be accommodated. Macromolecular crystallization using microfluidic technology is envisioned as a fully automated system, which will use the 'tele-science' concept of remote operation and will be developed into a research facility aboard the International Space Station.

Motility and Adhesiveness in Human Neutrophils

PubMed Central

Smith, C. Wayne; Hollers, James C.; Patrick, Richard A.; Hassett, Clare

1979-01-01

Human peripheral blood neutrophils (PMN) obtained from healthy adults were examined in vitro with techniques adapted to assess the effects of chemotactic factors (CF) on cellular configuration and adhesiveness. The results were compared with those that use certain conventional techniques for assessing chemotaxis and chemokinesis. Exposure of PMN to N-formyl-l-methionyl-l-phenylalanine (f-Met-Phe), zymosan-activated serum, bacterial chemotactic factor, or a low molecular weight chemotactic factor from activated serum (C5a) in the absence of a gradient resulted in a change in cellular shape from a spherical to a polarized configuration in a high percentage of cells. This occurred rapidly in suspension, under conditions designed to exclude a role for cell adhesiveness, and was reversible upon removal of the CF. Restimulation of cells with the CF resulted in reappearance of the polarized configuration to the same extent as on initial stimulation with one exception: f-Met-Phe pretreated cells failed to respond to f-Met-Phe, though they responded fully to the other CF. Each CF caused a significant increase in PMN attachment to protein-coated glass. This enhanced adhesiveness was not reversible upon removal of the CF when the cells were treated under conditions shown to produce chemotactic deactivation. Cells treated under these conditions also exhibited significantly reduced motility on glass and in micropore filters in the absence of a gradient of CF. Bacterial chemotactic factor, even at high concentrations, failed to produce deactivation and did not cause a sustained enhancement of adhesiveness. Images PMID:372238

Optimal methylation noise for best chemotactic performance of E. coli

NASA Astrophysics Data System (ADS)

Dev, Subrata; Chatterjee, Sakuntala

2018-03-01

In response to a concentration gradient of chemoattractant, E. coli bacterium modulates the rotational bias of flagellar motors which control its run-and-tumble motion, to migrate towards regions of high chemoattractant concentration. Presence of stochastic noise in the biochemical pathway of the cell has important consequences on the switching mechanism of motor bias, which in turn affects the runs and tumbles of the cell in a significant way. We model the intracellular reaction network in terms of coupled time evolution of three stochastic variables—kinase activity, methylation level, and CheY-P protein level—and study the effect of methylation noise on the chemotactic performance of the cell. In presence of a spatially varying nutrient concentration profile, a good chemotactic performance allows the cell to climb up the concentration gradient quickly and localize in the nutrient-rich regions in the long time limit. Our simulations show that the best performance is obtained at an optimal noise strength. While it is expected that chemotaxis will be weaker for very large noise, it is counterintuitive that the performance worsens even when noise level falls below a certain value. We explain this striking result by detailed analysis of CheY-P protein level statistics for different noise strengths. We show that when the CheY-P level falls below a certain (noise-dependent) threshold the cell tends to move down the concentration gradient of the nutrient, which has a detrimental effect on its chemotactic response. This threshold value decreases as noise is increased, and this effect is responsible for noise-induced enhancement of chemotactic performance. In a harsh chemical environment, when the nutrient degrades with time, the amount of nutrient intercepted by the cell trajectory is an effective performance criterion. In this case also, depending on the nutrient lifetime, we find an optimum noise strength when the performance is at its best.

An intact acrosome is required for the chemotactic response to progesterone in mouse spermatozoa.

PubMed

Guidobaldi, Hector A; Hirohashi, Noritaka; Cubilla, Marisa; Buffone, Mariano G; Giojalas, Laura C

2017-04-01

Mammalian sperm become fertilization-competent in the oviduct, during a process known as capacitation that involves the acquisition of the ability to exocytose the acrosome but also the chemotactic responses-both of which contribute to successful fertilization. Chemotaxis is used by spermatozoa to orient and to locate the egg; the acrosome reaction facilitates sperm binding to and fusing with the egg membrane. Mammalian spermatozoa are able to sense picomolar concentrations of progesterone, which drives chemotactic behavior. The state of the acrosome during the chemotactic response, however, is unknown. Genetically modified mouse spermatozoa were employed in a chemotaxis assay under fluorescence microscopy to evaluate their acrosome status while swimming, allowing us to elucidate the acrosome integrity of sperm responding to progesterone-induced chemotaxis. We first showed that wild-type mouse spermatozoa chemotactically respond to a gradient of progesterone, and that the genetic modifications employed do not affect the chemotactic behavior of sperm to progesterone. Next, we found that acrosome-intact, but not acrosome-reacted, spermatozoa orient and respond to picomolar concentrations of progesterone and that chemotaxis normally occurs prior to the acrosome reaction. Our results suggest that premature commitment to acrosome exocytosis leads to navigation failure, so proper control and timing of the acrosome reaction is required for fertilization success and male fertility. © 2017 Wiley Periodicals, Inc.

Eukaryotic Chemotaxis: A Network of Signaling Pathways Controls Motility, Directional Sensing, and Polarity

PubMed Central

Swaney, Kristen F.; Huang, Chuan-Hsiang; Devreotes, Peter N.

2015-01-01

Chemotaxis, the directed migration of cells in chemical gradients, is a vital process in normal physiology and in the pathogenesis of many diseases. Chemotactic cells display motility, directional sensing, and polarity. Motility refers to the random extension of pseudopodia, which may be driven by spontaneous actin waves that propagate through the cytoskeleton. Directional sensing is mediated by a system that detects temporal and spatial stimuli and biases motility toward the gradient. Polarity gives cells morphologically and functionally distinct leading and lagging edges by relocating proteins or their activities selectively to the poles. By exploiting the genetic advantages of Dictyostelium, investigators are working out the complex network of interactions between the proteins that have been implicated in the chemotactic processes of motility, directional sensing, and polarity. PMID:20192768

Simulation of Paramecium Chemotaxis Exposed to Calcium Gradients.

PubMed

Sarvestani, Ali N; Shamloo, Amir; Ahmadian, Mohammad Taghi

2016-06-01

Paramecium or other ciliates have the potential to be utilized for minimally invasive surgery systems, making internal body organs accessible. Paramecium shows interesting responses to changes in the concentration of specific ions such as K(+), Mg(2+), and Ca(2+) in the ambient fluid. Some specific responses are observed as, changes in beat pattern of cilia and swimming toward or apart from the ion source. Therefore developing a model for chemotactic motility of small organisms is necessary in order to control the directional movements of these microorganisms before testing them. In this article, we have developed a numerical model, investigating the effects of Ca(2+) on swimming trajectory of Paramecium. Results for Ca(2+)-dependent chemotactic motility show that calcium gradients are efficient actuators for controlling the Paramecium swimming trajectory. After applying a very low Ca(2+) gradient, a directional chemotaxis of swimming Paramecium is observable in this model. As a result, chemotaxis is shown to be an efficient method for controlling the propulsion of these small organisms.

Coupled effect of chemotaxis and growth on microbial distributions in organic-amended aquifer sediments: Observations from laboratory and field studies

USGS Publications Warehouse

Wang, M.; Ford, R.M.; Harvey, R.W.

2008-01-01

The inter-relationship of growth and chemotactic response exhibited by two common soil-inhabiting bacteria was investigated to determine its impact on bacterial migration. Filter-chambers were used to simulate aquifer sediments characterized by vertical gradients of organic contaminants in both artificial groundwater flow systems in the laboratory and within the screened intervals of observation wells in a sandy aquifer. A labile model contaminant (acetate) was added to the top compartments of the three-part chambers, whereas bacteria with a demonstrated propensity to grow on and chemotactically respond to acetate were introduced to the lower compartments, The motility and chemotactic response of Pseudomonas putida F1 resulted in 40 to 110% greater abundances in the upper compartments and concomitant 22 to 70% depletions in the lower compartments relative to the nonchemotactic controls over 2 days. Bacteria were in greatest abundance within the sand plug that separated the upper and lower compartments where sharp acetate gradients induced a strong chemotactic response. This observation was consistent with predictions from a mathematical model. In agreement with the laboratory results, the down-well filter-chamber incubations with Pseudomonas stutzeri in the aquifer indicated that 91% fewer bacteria resided in the lower compartment than the control experiment without acetate at 15 h. The combination of chemotaxis and growth greatly accelerated the migration of bacteria toward and subsequent abundance at the higher acetate concentration. ?? 2008 American Chemical Society.

A visual study of chemotaxis of human lymphocytes using a collagen-gel assay.

PubMed

Wilkinson, P C

1985-01-21

Time-lapse cinematography was used to study the chemotactic responsiveness of human blood lymphocytes as defined by morphological orientation and directional locomotion in gradients. At present, evidence for lymphocyte chemotaxis is indirect since neither of these essential features can be demonstrated with Boyden filter assays. Few lymphocytes direct from blood were motile, but culture in vitro for 1-3 days increased the proportion of locomotor forms to 30-40%. These cells were placed on 3-D collagen gels, and a chemotactic source was presented nearby on a small filter placed on the surface of, or within, the gel. The minority of lymphocytes that were capable of locomotion showed chemotactic responses to filters soaked in lipopolysaccharide if fresh human serum (20%), but not heat-inactivated serum, was present. Lymphocytes responded by protrusion of a lamella in the direction of the gradient source: 76% of locomotor lymphocytes showed their first orientation into the 180 degrees sector facing the source. They then moved directionally towards the source. The response to purified C5 peptides was equivocal. The locomotor lymphocytes showed a chemotactic response to supernatant fluids derived from cultures of the adherent mononuclear cell fraction from human blood (greater than 80% monocytes), judged by the same criteria. No particular lymphocyte type constituted the locomotor population. After exposure to LPS-activated serum, both T and B lymphocytes showed locomotor forms. There were slightly more T4+ cells among the locomotor population than among the population as a whole.

Study of Chemotaxis and Cell–Cell Interactions in Cancer with Microfluidic Devices

PubMed Central

Sai, Jiqing; Rogers, Matthew; Hockemeyer, Kathryn; Wikswo, John P.; Richmond, Ann

2017-01-01

Microfluidic devices have very broad applications in biological assays from simple chemotaxis assays to much more complicated 3D bioreactors. In this chapter, we describe the design and methods for performing chemotaxis assays using simple microfluidic chemotaxis chambers. With these devices, using real-time video microscopy we can examine the chemotactic responses of neutrophil-like cells under conditions of varying gradient steepness or flow rate and then utilize software programs to calculate the speed and angles of cell migration as gradient steepness and flow are varied. Considering the shearing force generated on the cells by the constant flow that is required to produce and maintain a stable gradient, the trajectories of the cell migration will reflect the net result of both shear force generated by flow and the chemotactic force resulting from the chemokine gradient. Moreover, the effects of mutations in chemokine receptors or the presence of inhibitors of intracellular signals required for gradient sensing can be evaluated in real time. We also describe a method to monitor intracellular signals required for cells to alter cell polarity in response to an abrupt switch in gradient direction. Lastly, we demonstrate an in vitro method for studying the interactions of human cancer cells with human endothelial cells, fibroblasts, and leukocytes, as well as environmental chemokines and cytokines, using 3D microbioreactors that mimic the in vivo microenvironment. PMID:26921940

Microfluidic transwell inserts for generation of tissue culture-friendly gradients in well plates

PubMed Central

Sip, Christopher G.; Bhattacharjee, Nirveek; Folch, Albert

2015-01-01

Gradients of biochemical molecules play a key role in many physiological processes such as axon growth, tissue morphogenesis, and trans-epithelium nutrient transport, as well as in pathophysiological phenomena such as wound healing, immune response, bacterial invasion, and cancer metastasis. In this paper, we report a microfluidic transwell insert for generating quantifiable concentration gradients in a user-friendly and modular format that is compatible with conventional cell cultures and with tissue explant cultures. The device is simply inserted into a standard 6-well plate, where it hangs self-supported at a distance of ~250 μm above the cell culture surface. The gradient is created by small microflows from the device, through an integrated track-etched porous membrane, into the cell culture well. The microfluidic transwell can deliver stable, quantifiable gradients over a large area with extremely low fluid shear stress to dissociated cells or tissue explants cultured independently on the surface of a 6-well plate. We used finite-element modeling to describe the porous membrane flow and molecular transport and to predict gradients generated by the device. Using the device, we applied a gradient of the chemotactic peptide N-Formyl-Met-Leu-Phe (fMLP) to a large population of HL-60 cells (a neutrophil cell line) and directly observed the migration with time-lapse microscopy. On quantification of the chemotactic response with an automated tracking algorithm, we found 74% of the cells moving towards the gradient. Additionally, the modular design and low fluid shear stress made it possible to apply gradients of growth factors and second messengers to mouse retinal explant cultures. With a simplified interface and well-defined gradients, the microfluidic transwell device has potential for broad applications to gradient-sensing biology. PMID:24225908

Predicted molecular signaling guiding photoreceptor cell migration following transplantation into damaged retina

NASA Astrophysics Data System (ADS)

Unachukwu, Uchenna John; Warren, Alice; Li, Ze; Mishra, Shawn; Zhou, Jing; Sauane, Moira; Lim, Hyungsik; Vazquez, Maribel; Redenti, Stephen

2016-03-01

To replace photoreceptors lost to disease or trauma and restore vision, laboratories around the world are investigating photoreceptor replacement strategies using subretinal transplantation of photoreceptor precursor cells (PPCs) and retinal progenitor cells (RPCs). Significant obstacles to advancement of photoreceptor cell-replacement include low migration rates of transplanted cells into host retina and an absence of data describing chemotactic signaling guiding migration of transplanted cells in the damaged retinal microenvironment. To elucidate chemotactic signaling guiding transplanted cell migration, bioinformatics modeling of PPC transplantation into light-damaged retina was performed. The bioinformatics modeling analyzed whole-genome expression data and matched PPC chemotactic cell-surface receptors to cognate ligands expressed in the light-damaged retinal microenvironment. A library of significantly predicted chemotactic ligand-receptor pairs, as well as downstream signaling networks was generated. PPC and RPC migration in microfluidic ligand gradients were analyzed using a highly predicted ligand-receptor pair, SDF-1α - CXCR4, and both PPCs and RPCs exhibited significant chemotaxis. This work present a systems level model and begins to elucidate molecular mechanisms involved in PPC and RPC migration within the damaged retinal microenvironment.

Chemotactic and hydrodynamic effects on collective dynamics of self-diffusiophoretic Janus motors

NASA Astrophysics Data System (ADS)

Huang, Mu-Jie; Schofield, Jeremy; Kapral, Raymond

2017-12-01

Collective motion in nonequilibrium steady state suspensions of self-propelled Janus motors driven by chemical reactions can arise due to interactions coming from direct intermolecular forces, hydrodynamic flow effects, or chemotactic effects mediated by chemical gradients. The relative importance of these interactions depends on the reactive characteristics of the motors, the way in which the system is maintained in a steady state, and properties of the suspension, such as the volume fraction. From simulations of a microscopic hard collision model for the interaction of fluid particles with the Janus motor we show that dynamic cluster states exist and determine the interaction mechanisms that are responsible for their formation. The relative importance of chemotactic and hydrodynamic effects is identified by considering a microscopic model in which chemotactic effects are turned off while the full hydrodynamic interactions are retained. The system is maintained in a steady state by means of a bulk reaction in which product particles are reconverted into fuel particles. The influence of the bulk reaction rate on the collective dynamics is also studied.

Modelling the collective response of heterogeneous cell populations to stationary gradients and chemical signal relay

NASA Astrophysics Data System (ADS)

Pineda, M.; Eftimie, R.

2017-12-01

The directed motion of cell aggregates toward a chemical source occurs in many relevant biological processes. Understanding the mechanisms that control this complex behavior is of great relevance for our understanding of developmental biological processes and many diseases. In this paper, we consider a self-propelled particle model for the movement of heterogeneous subpopulations of chemically interacting cells towards an imposed stable chemical gradient. Our simulations show explicitly how self-organisation of cell populations (which could lead to engulfment or complete cell segregation) can arise from the heterogeneity of chemotactic responses alone. This new result complements current theoretical and experimental studies that emphasise the role of differential cell-cell adhesion on self-organisation and spatial structure of cellular aggregates. We also investigate how the speed of individual cell aggregations increases with the chemotactic sensitivity of the cells, and decreases with the number of cells inside the aggregates

Clusters, asters, and collective oscillations in chemotactic colloids

NASA Astrophysics Data System (ADS)

Saha, Suropriya; Golestanian, Ramin; Ramaswamy, Sriram

2014-06-01

The creation of synthetic systems that emulate the defining properties of living matter, such as motility, gradient-sensing, signaling, and replication, is a grand challenge of biomimetics. Such imitations of life crucially contain active components that transform chemical energy into directed motion. These artificial realizations of motility point in the direction of a new paradigm in engineering, through the design of emergent behavior by manipulating properties at the scale of the individual components. Catalytic colloidal swimmers are a particularly promising example of such systems. Here we present a comprehensive theoretical description of gradient-sensing of an individual swimmer, leading controllably to chemotactic or anti-chemotactic behavior, and use it to construct a framework for studying their collective behavior. We find that both the positional and the orientational degrees of freedom of the active colloids can exhibit condensation, signaling formation of clusters and asters. The kinetics of catalysis introduces a natural control parameter for the range of the interaction mediated by the diffusing chemical species. For various regimes in parameter space in the long-ranged limit our system displays precise analogs to gravitational collapse, plasma oscillations, and electrostatic screening. We present prescriptions for how to tune the surface properties of the colloids during fabrication to achieve each type of behavior.

Bacteria foraging in turbulent waters

NASA Astrophysics Data System (ADS)

Taylor, John; Tang, Wenbo; Stocker, Roman

2009-11-01

Marine bacteria are the Ocean's recyclers, contributing to as much as 50% of the productivity of the marine food web. Bacteria forage on patches of dissolved nutrients using chemotaxis, the ability to swim up chemical gradients. As turbulence is ubiquitous in the Ocean, it is important to understand how turbulent flow conditions affect bacterial foraging. We used three-dimensional, isotropic direct numerical simulations coupled with a bacterial transport equation to address this problem. After the flow is continuously forced until it reaches a steady state, microscale nutrient patches are injected into the turbulent flow, and stirring produces thin nutrient filaments. Two populations of bacteria compete against each other: one population is motile and chemotactic (`active'), the other is non-motile (`passive'). The distribution of both populations is initially uniform. Chemotaxis allows active bacteria to cluster near the center of the nutrient filaments, increasing their nutrient uptake relative to passive bacteria. Increasing the turbulence intensity increases the short-term chemotactic advantage by quickly producing large gradients in the nutrient concentration, but also leads to rapid mixing of the nutrient field, which makes the chemotactic advantage short-lived. The results suggest that the evolutionary advantage of chemotaxis, based on the increase in nutrient uptake relative to the energetic cost of swimming, strongly depends on the turbulence level.

Unique mechanism of Helicobacter pylori for colonizing the gastric mucus.

PubMed

Yoshiyama, H; Nakazawa, T

2000-01-01

Helicobacter pylori is a human gastric pathogen causing chronic infection. Urease and motility using flagella are essential factors for its colonization. Urease of H. pylori exists both on the surface and in the cytoplasm, and is involved in neutralizing gastric acid and in chemotactic motility. H. pylori senses the concentration gradients of urea in the gastric mucus layer, then moves toward the epithelial surface by chemotactic movement. The energy source for the flagella movement is the proton motive force. The hydrolysis of urea by the cytoplasmic urease possibly generates additional energy for the flagellar rotation in the mucus gel layer.

Migration of Chemotactic Bacteria Transverse to Flow in Response to a Benzoate Source Plume Created in a Saturated Sand-Packed Microcosm

NASA Astrophysics Data System (ADS)

Ford, R.; Boser, B.

2012-12-01

Bioremediation processes depend on contact between microbial populations and the groundwater contaminants that they biodegrade. Chemotaxis, the ability of bacteria to sense a chemical gradient and swim preferentially toward locations of higher concentration, can enhance the transport of bacteria toward contaminant sources that may not be readily accessible by advection and dispersion alone. A two-dimensional rectangular-shaped microcosm packed with quartz sand was used to quantify the effect of chemotaxis on the migration of bacteria within a saturated model aquifer system. Artificial groundwater was pumped through the microcosm at a rate of approximately 1 m/day. A plume of sodium benzoate was created by continuous injection into an upper port of the microcosm to generate a chemical gradient in the vertical direction transverse to flow. Chemotactic bacteria, Pseudomonas putida F1, or the nonchemotactic mutant, P. putida F1 CheA, were injected with a conservative tracer in a port several centimeters below the benzoate position. As the injectates traversed the one-meter length of the microcosm, samples were collected from a dozen effluent ports to determine vertical concentration distributions for the bacteria, benzoate and tracer. A moment analysis was implemented to estimate the center of mass, variance, and skewness of the concentration profiles. The transverse dispersion coefficient and the transverse dispersivity for chemotactic and nonchemotactic bacteria were also evaluated. Experiments performed with a continuous injection of bacteria showed that the center of mass for chemotactic bacteria was closer to the benzoate source on average than the nonchemotactic control (relative to the conservative tracer). These results demonstrated that chemotaxis can increase bacterial transport toward contaminants, potentially enhancing the effectiveness of in situ bioremediation. Experiments with 2 cm and 3 cm spacing between bacteria and benzoate injection locations were performed to explore the relationship between the exposure time of the bacteria to benzoate and the transverse migration of bacteria due to chemotaxis. Experimentally determined transport parameters were then used as input to a two-dimensional mathematical model for bacterial transport. Model results showed the shift in center of mass for chemotactic bacteria was greater for 2 cm and 3 cm spacing than for 4 cm spacing for a given chemotactic sensitivity coefficient value, which showed that an increase in the exposure time of the bacteria to the model contaminant benzoate increased the transverse migration of bacteria. Modeling was used to test the effects of changing the chemotactic sensitivity coefficient and the chemotaxis receptor constant at three different bacteria and benzoate separation distances: 2 cm, 3 cm, and 4 cm. Mathematical models from this work can be applied to future field-scale studies to select design parameters that maximize transverse migration of chemotactic bacteria.

Chemotaxis of Cell Populations through Confined Spaces at Single-Cell Resolution

PubMed Central

Tong, ZiQiu; Balzer, Eric M.; Dallas, Matthew R.; Hung, Wei-Chien; Stebe, Kathleen J.; Konstantopoulos, Konstantinos

2012-01-01

Cell migration is crucial for both physiological and pathological processes. Current in vitro cell motility assays suffer from various drawbacks, including insufficient temporal and/or optical resolution, or the failure to include a controlled chemotactic stimulus. Here, we address these limitations with a migration chamber that utilizes a self-sustaining chemotactic gradient to induce locomotion through confined environments that emulate physiological settings. Dynamic real-time analysis of both population-scale and single-cell movement are achieved at high resolution. Interior surfaces can be functionalized through adsorption of extracellular matrix components, and pharmacological agents can be administered to cells directly, or indirectly through the chemotactic reservoir. Direct comparison of multiple cell types can be achieved in a single enclosed system to compare inherent migratory potentials. Our novel microfluidic design is therefore a powerful tool for the study of cellular chemotaxis, and is suitable for a wide range of biological and biomedical applications. PMID:22279529

Effect of Porous Media Particle Size on Bacterial Motility and Chemotaxis

NASA Astrophysics Data System (ADS)

Olson, M. S.; Smith, J. A.; Ford, R. M.; Fernandez, E. J.

2003-12-01

Many soil-inhabiting bacteria that degrade chemical contaminants are both motile and chemotactic. Chemotaxis refers to the ability of bacteria to sense pollutant concentration gradients in water and preferentially swim toward regions of high pollutant concentration, and is thought to be important in guiding subsurface microbial populations toward chemical contaminants. Bacterial motion consists of a series of smooth-swimming runs interrupted by changes in direction. In the presence of a chemical gradient, bacteria bias their frequency of changing direction and demonstrate longer run lengths in the direction of increasing attractant concentration. One concern when studying bacterial chemotaxis in porous media is that in small pores, the porous media may interrupt the extended run lengths of bacteria swimming in the direction of a positive chemical gradient. The purpose of this study is to examine how a decrease in particle size affects the motility and chemotactic response of bacteria traveling through porous media. We employ an innovative technique for noninvasive visualization of changes in bacterial density distributions in a packed column as a function of time. Paramagnetic magnetite particles are attached to the surface of Pseudomonas putida F1 cells using an antibody. Bacterial distributions within a column of glass-coated polystyrene beads are imaged using magnetic resonance imaging (MRI), with a spatial resolution of 300 μ m. Experiments are conducted with both 250-300 μ m beads and 90-150 μ m beads. Bacteria labeled with magnetite are introduced into a specially designed chromatography column packed with glass-coated polystyrene beads. Bacterial migration is monitored over time using MRI, with and without the presence of a chemical gradient of trichloroethylene (TCE). Comparisons of the motility and chemotactic transport coefficients for Pseudomonas putida F1 cells traveling through different-sized samples of porous media in the presence of TCE will be presented and discussed. Results suggest a decrease in both motility and chemotaxis in the smaller-sized porous media.

Automated Chemotactic Sorting and Single-cell Cultivation of Microbes using Droplet Microfluidics

NASA Astrophysics Data System (ADS)

Dong, Libing; Chen, Dong-Wei; Liu, Shuang-Jiang; Du, Wenbin

2016-04-01

We report a microfluidic device for automated sorting and cultivation of chemotactic microbes from pure cultures or mixtures. The device consists of two parts: in the first part, a concentration gradient of the chemoeffector was built across the channel for inducing chemotaxis of motile cells; in the second part, chemotactic cells from the sample were separated, and mixed with culture media to form nanoliter droplets for encapsulation, cultivation, enumeration, and recovery of single cells. Chemotactic responses were assessed by imaging and statistical analysis of droplets based on Poisson distribution. An automated procedure was developed for rapid enumeration of droplets with cell growth, following with scale-up cultivation on agar plates. The performance of the device was evaluated by the chemotaxis assays of Escherichia coli (E. coli) RP437 and E. coli RP1616. Moreover, enrichment and isolation of non-labelled Comamonas testosteroni CNB-1 from its 1:10 mixture with E. coli RP437 was demonstrated. The enrichment factor reached 36.7 for CNB-1, based on its distinctive chemotaxis toward 4-hydroxybenzoic acid. We believe that this device can be widely used in chemotaxis studies without necessarily relying on fluorescent labelling, and isolation of functional microbial species from various environments.

Automated Chemotactic Sorting and Single-cell Cultivation of Microbes using Droplet Microfluidics.

PubMed

Dong, Libing; Chen, Dong-Wei; Liu, Shuang-Jiang; Du, Wenbin

2016-04-14

We report a microfluidic device for automated sorting and cultivation of chemotactic microbes from pure cultures or mixtures. The device consists of two parts: in the first part, a concentration gradient of the chemoeffector was built across the channel for inducing chemotaxis of motile cells; in the second part, chemotactic cells from the sample were separated, and mixed with culture media to form nanoliter droplets for encapsulation, cultivation, enumeration, and recovery of single cells. Chemotactic responses were assessed by imaging and statistical analysis of droplets based on Poisson distribution. An automated procedure was developed for rapid enumeration of droplets with cell growth, following with scale-up cultivation on agar plates. The performance of the device was evaluated by the chemotaxis assays of Escherichia coli (E. coli) RP437 and E. coli RP1616. Moreover, enrichment and isolation of non-labelled Comamonas testosteroni CNB-1 from its 1:10 mixture with E. coli RP437 was demonstrated. The enrichment factor reached 36.7 for CNB-1, based on its distinctive chemotaxis toward 4-hydroxybenzoic acid. We believe that this device can be widely used in chemotaxis studies without necessarily relying on fluorescent labelling, and isolation of functional microbial species from various environments.

Dimethyl Sulfoxide (DMSO) Increases Percentage of CXCR4(+) Hematopoietic Stem/Progenitor Cells, Their Responsiveness to an SDF-1 Gradient, Homing Capacities, and Survival.

PubMed

Jarocha, Danuta; Zuba-Surma, Ewa; Majka, Marcin

2016-01-01

Cryopreservation of bone marrow (BM), mobilized peripheral blood (mPB), and cord blood (CB) hematopoietic stem/progenitor cells (HSPCs) is a routine procedure before transplantation. The most commonly used cryoprotectant for HSPCs is dimethyl sulfoxide (DMSO). The objective of this study was to evaluate the influence of DMSO on surface receptor expression and chemotactic activities of HSPCs. We found that 10 min of incubation of human mononuclear cells (MNCs) with 10% DMSO significantly increases the percentage of CXCR4(+), CD38(+), and CD34(+) cells, resulting in an increase of CD34(+), CD34(+)CXCR4(+), and CD34(+)CXCR4(+)CD38(-) subpopulations. Furthermore, DMSO significantly increased chemotactic responsiveness of MNCs and CXCR4(+) human hematopoietic Jurkat cell line to a stromal cell-derived factor-1 (SDF-1) gradient. Furthermore, we demonstrated enhanced chemotaxis of human clonogenic progenitor cells to an SDF-1 gradient, which suggests that DMSO directly enhances the chemotactic responsiveness of early human progenitors. DMSO preincubation also caused lower internalization of the CXCR4 receptor. In parallel experiments, we found that approximately 30% more of DMSO-preincubated human CD45(+) and CD45(+)CD34(+) cells homed to the mouse BM 24 h after transplantation in comparison to control cells. Finally, we demonstrated considerably higher (25 days) survival of mice transplanted with DMSO-exposed MNCs than those transplanted with the control cells. We show in this study an unexpected beneficial influence of DMSO on HSPC homing and suggest that a short priming with DMSO before transplantation could be considered a new strategy to enhance cell homing and engraftment.

Drift and Behavior of E. coli Cells

NASA Astrophysics Data System (ADS)

Micali, Gabriele; Colin, Rémy; Sourjik, Victor; Endres, Robert G.

2017-12-01

Chemotaxis of the bacterium Escherichia coli is well understood in shallow chemical gradients, but its swimming behavior remains difficult to interpret in steep gradients. By focusing on single-cell trajectories from simulations, we investigated the dependence of the chemotactic drift velocity on attractant concentration in an exponential gradient. While maxima of the average drift velocity can be interpreted within analytical linear-response theory of chemotaxis in shallow gradients, limits in drift due to steep gradients and finite number of receptor-methylation sites for adaptation go beyond perturbation theory. For instance, we found a surprising pinning of the cells to the concentration in the gradient at which cells run out of methylation sites. To validate the positions of maximal drift, we recorded single-cell trajectories in carefully designed chemical gradients using microfluidics.

Cell Blebbing in Confined Microfluidic Environments

PubMed Central

Ibo, Markela; Srivastava, Vasudha; Robinson, Douglas N.; Gagnon, Zachary R.

2016-01-01

Migrating cells can extend their leading edge by forming myosin-driven blebs and F-actin-driven pseudopods. When coerced to migrate in resistive environments, Dictyostelium cells switch from using predominately pseudopods to blebs. Bleb formation has been shown to be chemotactic and can be influenced by the direction of the chemotactic gradient. In this study, we determine the blebbing responses of developed cells of Dictyostelium discoideum to cAMP gradients of varying steepness produced in microfluidic channels with different confining heights, ranging between 1.7 μm and 3.8 μm. We show that microfluidic confinement height, gradient steepness, buffer osmolarity and Myosin II activity are important factors in determining whether cells migrate with blebs or with pseudopods. Dictyostelium cells were observed migrating within the confines of microfluidic gradient channels. When the cAMP gradient steepness is increased from 0.7 nM/μm to 20 nM/μm, cells switch from moving with a mixture of blebs and pseudopods to moving only using blebs when chemotaxing in channels with confinement heights less than 2.4 μm. Furthermore, the size of the blebs increases with gradient steepness and correlates with increases in myosin-II localization at the cell cortex. Reduction of intracellular pressure by high osmolarity buffer or inhibition of myosin-II by blebbistatin leads to a decrease in bleb formation and bleb size. Together, our data reveal that the protrusion type formed by migrating cells can be influenced by the channel height and the steepness of the cAMP gradient, and suggests that a combination of confinement-induced myosin-II localization and cAMP-regulated cortical contraction leads to increased intracellular fluid pressure and bleb formation. PMID:27706201

Analysis of bacterial migration. 2: Studies with multiple attractant gradients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strauss, I.; Frymier, P.D.; Hahn, C.M.

1995-02-01

Many motile bacteria exhibit chemotaxis, the ability to bias their random motion toward or away from increasing concentrations of chemical substances which benefit or inhibit their survival, respectively. Since bacteria encounter numerous chemical concentration gradients simultaneously in natural surroundings, it is necessary to know quantitatively how a bacterial population responds in the presence of more than one chemical stimulus to develop predictive mathematical models describing bacterial migration in natural systems. This work evaluates three hypothetical models describing the integration of chemical signals from multiple stimuli: high sensitivity, maximum signal, and simple additivity. An expression for the tumbling probability for individualmore » stimuli is modified according to the proposed models and incorporated into the cell balance equation for a 1-D attractant gradient. Random motility and chemotactic sensitivity coefficients, required input parameters for the model, are measured for single stimulus responses. Theoretical predictions with the three signal integration models are compared to the net chemotactic response of Escherichia coli to co- and antidirectional gradients of D-fucose and [alpha]-methylaspartate in the stopped-flow diffusion chamber assay. Results eliminate the high-sensitivity model and favor the simple additivity over the maximum signal. None of the simple models, however, accurately predict the observed behavior, suggesting a more complex model with more steps in the signal processing mechanism is required to predict responses to multiple stimuli.« less

Analytical modeling and experimental characterization of chemotaxis in Serratia marcescens

NASA Astrophysics Data System (ADS)

Zhuang, Jiang; Wei, Guopeng; Wright Carlsen, Rika; Edwards, Matthew R.; Marculescu, Radu; Bogdan, Paul; Sitti, Metin

2014-05-01

This paper presents a modeling and experimental framework to characterize the chemotaxis of Serratia marcescens (S. marcescens) relying on two-dimensional and three-dimensional tracking of individual bacteria. Previous studies mainly characterized bacterial chemotaxis based on population density analysis. Instead, this study focuses on single-cell tracking and measuring the chemotactic drift velocity VC from the biased tumble rate of individual bacteria on exposure to a concentration gradient of l-aspartate. The chemotactic response of S. marcescens is quantified over a range of concentration gradients (10-3 to 5 mM/mm) and average concentrations (0.5×10-3 to 2.5 mM). Through the analysis of a large number of bacterial swimming trajectories, the tumble rate is found to have a significant bias with respect to the swimming direction. We also verify the relative gradient sensing mechanism in the chemotaxis of S. marcescens by measuring the change of VC with the average concentration and the gradient. The applied full pathway model with fitted parameters matches the experimental data. Finally, we show that our measurements based on individual bacteria lead to the determination of the motility coefficient μ (7.25×10-6 cm2/s) of a population. The experimental characterization and simulation results for the chemotaxis of this bacterial species contribute towards using S. marcescens in chemically controlled biohybrid systems.

A simple expression for quantifying bacterial chemotaxis using capillary assay data: application to the analysis of enhanced chemotactic responses from growth-limited cultures.

PubMed

Ford, R M; Lauffenburger, D A

1992-05-01

An individual cell-based mathematical model of Rivero et al. provides a framework for determining values of the chemotactic sensitivity coefficient chi 0, an intrinsic cell population parameter that characterizes the chemotactic response of bacterial populations. This coefficient can theoretically relate the swimming behavior of individual cells to the resulting migration of a bacterial population. When this model is applied to the commonly used capillary assay, an approximate solution can be obtained for a particular range of chemotactic strengths yielding a very simple analytical expression for estimating the value of chi 0, [formula: see text] from measurements of cell accumulation in the capillary, N, when attractant uptake is negligible. A0 and A infinity are the dimensionless attractant concentrations initially present at the mouth of the capillary and far into the capillary, respectively, which are scaled by Kd, the effective dissociation constant for receptor-attractant binding. D is the attractant diffusivity, and mu is the cell random motility coefficient. NRM is the cell accumulation in the capillary in the absence of an attractant gradient, from which mu can be determined independently as mu = (pi/4t)(NRM/pi r2bc)2, with r the capillary tube radius and bc the bacterial density initially in the chamber. When attractant uptake is significant, a slightly more involved procedure requiring a simple numerical integration becomes necessary. As an example, we apply this approach to quantitatively characterize, in terms of the chemotactic sensitivity coefficient chi 0, data from Terracciano indicating enhanced chemotactic responses of Escherichia coli to galactose when cultured under growth-limiting galactose levels in a chemostat.

Physical mechanisms for chemotactic pattern formation by bacteria.

PubMed Central

Brenner, M P; Levitov, L S; Budrene, E O

1998-01-01

This paper formulates a theory for chemotactic pattern formation by the bacteria Escherichia coli in the presence of excreted attractant. In a chemotactically neutral background, through chemoattractant signaling, the bacteria organize into swarm rings and aggregates. The analysis invokes only those physical processes that are both justifiable by known biochemistry and necessary and sufficient for swarm ring migration and aggregate formation. Swarm rings migrate in the absence of an external chemoattractant gradient. The ring motion is caused by the depletion of a substrate that is necessary to produce attractant. Several scaling laws are proposed and are demonstrated to be consistent with experimental data. Aggregate formation corresponds to finite time singularities in which the bacterial density diverges at a point. Instabilities of swarm rings leading to aggregate formation occur via a mechanism similar to aggregate formation itself: when the mass density of the swarm ring exceeds a threshold, the ring collapses cylindrically and then destabilizes into aggregates. This sequence of events is demonstrated both in the theoretical model and in the experiments. PMID:9545032

Active Brownian agents with concentration-dependent chemotactic sensitivity.

PubMed

Meyer, Marcel; Schimansky-Geier, Lutz; Romanczuk, Pawel

2014-02-01

We study a biologically motivated model of overdamped, autochemotactic Brownian agents with concentration-dependent chemotactic sensitivity. The agents in our model move stochastically and produce a chemical ligand at their current position. The ligand concentration obeys a reaction-diffusion equation and acts as a chemoattractant for the agents, which bias their motion towards higher concentrations of the dynamically altered chemical field. We explore the impact of concentration-dependent response to chemoattractant gradients on large-scale pattern formation, by deriving a coarse-grained macroscopic description of the individual-based model, and compare the conditions for emergence of inhomogeneous solutions for different variants of the chemotactic sensitivity. We focus primarily on the so-called receptor-law sensitivity, which models a nonlinear decrease of chemotactic sensitivity with increasing ligand concentration. Our results reveal qualitative differences between the receptor law, the constant chemotactic response, and the so-called log law, with respect to stability of the homogeneous solution, as well as the emergence of different patterns (labyrinthine structures, clusters, and bubbles) via spinodal decomposition or nucleation. We discuss two limiting cases, where the model can be reduced to the dynamics of single species: (I) the agent density governed by a density-dependent effective diffusion coefficient and (II) the ligand field with an effective bistable, time-dependent reaction rate. In the end, we turn to single clusters of agents, studying domain growth and determining mean characteristics of the stationary inhomogeneous state. Analytical results are confirmed and extended by large-scale GPU simulations of the individual based model.

Highly Permeable Silicon Membranes for Shear Free Chemotaxis and Rapid Cell Labeling

PubMed Central

Chung, Henry H.; Chan, Charles K.; Khire, Tejas S.; Marsh, Graham A.; Clark, Alfred; Waugh, Richard E.; McGrath, James L.

2015-01-01

Microfluidic systems are powerful tools for cell biology studies because they enable the precise addition and removal of solutes in small volumes. However, the fluid forces inherent in the use of microfluidics for cell cultures are sometimes undesirable. An important example is chemotaxis systems where fluid flow creates well-defined and steady chemotactic gradients but also pushes cells downstream. Here we demonstrate a chemotaxis system in which two chambers are separated by a molecularly thin (15 nm), transparent, and nanoporous silicon membrane. One chamber is a microfluidic channel that carries a flow-generated gradient while the other chamber is a shear-free environment for cell observation. The molecularly thin membranes provide effectively no resistance to molecular diffusion between the two chambers, making them ideal elements for creating flow-free chambers in microfluidic systems. Analytical and computational flow models that account for membrane and chamber geometry, predict shear reduction of more than five orders of magnitude. This prediction is confirmed by observing the pure diffusion of nanoparticles in the cell-hosting chamber despite high input flow (Q = 10 µL min−1; vavg ~45 mm min−1) in the flow chamber only 15 nm away. Using total internal reflection fluorescence (TIRF) microscopy, we show that a flow-generated molecular gradient will pass through the membrane into the quiescent cell chamber. Finally we demonstrate that our device allows us to expose migrating neutrophils to a chemotactic gradient or fluorescent label without any influence from flow. PMID:24850320

Marangoni-driven chemotaxis, chemotactic collapse, and the Keller-Segel equation

NASA Astrophysics Data System (ADS)

Shelley, Michael; Masoud, Hassan

2013-11-01

Almost by definition, chemotaxis involves the biased motion of motile particles along gradients of a chemical concentration field. Perhaps the most famous model for collective chemotaxis in mathematical biology is the Keller-Segel model, conceived to describe collective aggregation of slime mold colonies in response to an intrinsically produced, and diffusing, chemo-attractant. Heavily studied, particularly in 2D where the system is ``super-critical'', it has been proved that the KS model can develop finite-time singularities - so-called chemotactic collapse - of delta-function type. Here, we study the collective dynamics of immotile particles bound to a 2D interface above a 3D fluid. These particles are chemically active and produce a diffusing field that creates surface-tension gradients along the surface. The resultant Marangoni stresses create flows that carry the particles, possibly concentrating them. Remarkably, we show that this system involving 3D diffusion and fluid dynamics, exactly yields the 2D Keller-Segel model for the surface-flow of active particles. We discuss the consequences of collapse on the 3D fluid dynamics, and generalizations of the fluid-dynamical model.

The directional response of chemotactic cells depends on a balance between cytoskeletal architecture and the external gradient.

PubMed

Wang, Ming-Jie; Artemenko, Yulia; Cai, Wen-Jie; Iglesias, Pablo A; Devreotes, Peter N

2014-11-06

Polarized migrating cells display signal transduction events, such as activation of phosphatidylinositol 3-kinase (PI3K) and Scar/Wave, and respond more readily to chemotactic stimuli at the leading edge. We sought to determine the basis of this polarized sensitivity. Inhibiting actin polymerization leads to uniform sensitivity. However, when human neutrophils were "stalled" by simultaneously blocking actin and myosin dynamics, they maintained the gradient of responsiveness to chemoattractant and also displayed noise-driven PIP3 flashes on the basal membrane, localized toward the front. Thus, polarized sensitivity does not require migration or cytoskeletal dynamics. The threshold for response is correlated with the static F-actin distribution, but not cell shape or volume changes, membrane fluidity, or the preexisting distribution of PI3K. The kinetics of responses to temporal and spatial stimuli were consistent with the local excitation global inhibition model, but the overall direction of the response was biased by the internal axis of polarity. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Substrate-driven chemotactic assembly in an enzyme cascade.

PubMed

Zhao, Xi; Palacci, Henri; Yadav, Vinita; Spiering, Michelle M; Gilson, Michael K; Butler, Peter J; Hess, Henry; Benkovic, Stephen J; Sen, Ayusman

2018-03-01

Enzymatic catalysis is essential to cell survival. In many instances, enzymes that participate in reaction cascades have been shown to assemble into metabolons in response to the presence of the substrate for the first enzyme. However, what triggers metabolon formation has remained an open question. Through a combination of theory and experiments, we show that enzymes in a cascade can assemble via chemotaxis. We apply microfluidic and fluorescent spectroscopy techniques to study the coordinated movement of the first four enzymes of the glycolysis cascade: hexokinase, phosphoglucose isomerase, phosphofructokinase and aldolase. We show that each enzyme independently follows its own specific substrate gradient, which in turn is produced by the preceding enzymatic reaction. Furthermore, we find that the chemotactic assembly of enzymes occurs even under cytosolic crowding conditions.

Substrate-driven chemotactic assembly in an enzyme cascade

NASA Astrophysics Data System (ADS)

Zhao, Xi; Palacci, Henri; Yadav, Vinita; Spiering, Michelle M.; Gilson, Michael K.; Butler, Peter J.; Hess, Henry; Benkovic, Stephen J.; Sen, Ayusman

2018-03-01

Enzymatic catalysis is essential to cell survival. In many instances, enzymes that participate in reaction cascades have been shown to assemble into metabolons in response to the presence of the substrate for the first enzyme. However, what triggers metabolon formation has remained an open question. Through a combination of theory and experiments, we show that enzymes in a cascade can assemble via chemotaxis. We apply microfluidic and fluorescent spectroscopy techniques to study the coordinated movement of the first four enzymes of the glycolysis cascade: hexokinase, phosphoglucose isomerase, phosphofructokinase and aldolase. We show that each enzyme independently follows its own specific substrate gradient, which in turn is produced by the preceding enzymatic reaction. Furthermore, we find that the chemotactic assembly of enzymes occurs even under cytosolic crowding conditions.

Enhanced Retention of Chemotactic Bacteria in a Pore Network with Residual NAPL Contamination

NASA Astrophysics Data System (ADS)

Ford, R.; Wang, X.

2013-12-01

Nonaqueous phase liquid (NAPL) contaminants are difficult to eliminate from natural aquifers due, in part, to the heterogeneous structure of the soil matrix. Residual NAPL ganglia remain trapped in regions where the hydraulic conductivity is relatively low. Bioremediation processes depend on adequate mixing of microbial populations and the groundwater contaminants that they degrade. The ability of bacteria to sense a chemical gradient and swim preferentially toward locations of higher concentration, known as chemotaxis, can enhance the mixing of bacteria with contaminant sources that may not be readily accessible by advection and dispersion alone. The impact of chemotaxis on bacterial abundance within a low conductivity NAPL-contaminated region of a well-characterized porous matrix was investigated. A microfluidic device was designed to mimic heterogeneous features of a contaminated groundwater system. NAPL ganglia (toluene) were trapped within a fine pore network, and bacteria were injected into the system through a highly conductive adjacent channel. Chemotactic bacteria (P. putida F1) migrated preferentially towards and accumulated in the vicinity of NAPL contaminant sources. The accumulation of chemotactic bacteria was 15% greater in comparison to a nonchemotactic mutant (P. putida F1 CheA). Bacteria in the microfluidic device were subjected to different flow velocities from 0.25 to 5 m/d encompassing the range of typical groundwater flow rates. Chemotactic bacteria exhibited greater accumulation near the intersection between the macrochannel and the porous network at a flow velocity of 0.5 m/d than both the nonchemotactic mutant control and the chemotactic bacteria at a higher flow velocity of 5 m/d. Breakthrough curves observed at the outlet provided indirect evidence that chemotactic bacteria were retained within the contaminated low permeable region for a longer time than the nonchemotactic bacteria at a flow velocity of 0.25 m/d. This retention was diminished at a higher flow velocity of 5 m/d. Numerical solutions of the governing equations for bacterial transport yielded outcomes that were consistent with the experimental results, and statistical analysis also supported the experimental comparisons. The chemotactic response aided efficient delivery of bacteria to NAPL contaminant sources within the low conductivity pore network. Because toluene is degraded by P. putida F1, the greater accumulation of chemotactic bacteria around the NAPL sources is also expected to increase contaminant consumption and improve the efficiency of bioremediation.

Quantitative analysis of transverse bacterial migration induced by chemotaxis in a packed column with structured physical heterogeneity.

PubMed

Wang, Meng; Ford, Roseanne M

2010-01-15

A two-dimensional mathematical model was developed to simulate transport phenomena of chemotactic bacteria in a sand-packed column designed with structured physical heterogeneity in the presence of a localized chemical source. In contrast to mathematical models in previous research work, in which bacteria were typically treated as immobile colloids, this model incorporated a convective-like chemotaxis term to represent chemotactic migration. Consistency between experimental observation and model prediction supported the assertions that (1) dispersion-induced microbial transfer between adjacent conductive zones occurred at the interface and had little influence on bacterial transport in the bulk flow of the permeable layers and (2) the enhanced transverse bacterial migration in chemotactic experiments relative to nonchemotactic controls was mainly due to directed migration toward the chemical source zone. On the basis of parameter sensitivity analysis, chemotactic parameters determined in bulk aqueous fluid were adequate to predict the microbial transport in our intermediate-scale porous media system. Additionally, the analysis of adsorption coefficient values supported the observation of a previous study that microbial deposition to the surface of porous media might be decreased under the effect of chemoattractant gradients. By quantitatively describing bacterial transport and distribution in a heterogeneous system, this mathematical model serves to advance our understanding of chemotaxis and motility effects in granular media systems and provides insights for modeling microbial transport in in situ microbial processes.

A dual-docking microfluidic cell migration assay (D2-Chip) for testing neutrophil chemotaxis and the memory effect.

PubMed

Yang, Ke; Wu, Jiandong; Xu, Guoqing; Xie, Dongxue; Peretz-Soroka, Hagit; Santos, Susy; Alexander, Murray; Zhu, Ling; Zhang, Michael; Liu, Yong; Lin, Francis

2017-04-18

Chemotaxis is a classic mechanism for guiding cell migration and an important topic in both fundamental cell biology and health sciences. Neutrophils are a widely used model to study eukaryotic cell migration and neutrophil chemotaxis itself can lead to protective or harmful immune actions to the body. While much has been learnt from past research about how neutrophils effectively navigate through a chemoattractant gradient, many interesting questions remain unclear. For example, while it is tempting to model neutrophil chemotaxis using the well-established biased random walk theory, the experimental proof was challenged by the cell's highly persistent migrating nature. A special experimental design is required to test the key predictions from the random walk model. Another question that has interested the cell migration community for decades concerns the existence of chemotactic memory and its underlying mechanism. Although chemotactic memory has been suggested in various studies, a clear quantitative experimental demonstration will improve our understanding of the migratory memory effect. Motivated by these questions, we developed a microfluidic cell migration assay (so-called dual-docking chip or D 2 -Chip) that can test both the biased random walk model and the memory effect for neutrophil chemotaxis on a single chip enabled by multi-region gradient generation and dual-region cell alignment. Our results provide experimental support for the biased random walk model and chemotactic memory for neutrophil chemotaxis. Quantitative data analyses provide new insights into neutrophil chemotaxis and memory by making connections to entropic disorder, cell morphology and oscillating migratory response.

Elevated CXCL1 expression in gp130-deficient endothelial cells impairs neutrophil migration in mice

PubMed Central

Yao, Longbiao; Yago, Tadayuki; Shao, Bojing; Liu, Zhenghui; Silasi-Mansat, Robert; Setiadi, Hendra; Lupu, Florea

2013-01-01

Neutrophils emigrate from venules to sites of infection or injury in response to chemotactic gradients. How these gradients form is not well understood. Some IL-6 family cytokines stimulate endothelial cells to express adhesion molecules and chemokines that recruit leukocytes. Receptors for these cytokines share the signaling subunit gp130. We studied knockout mice lacking gp130 in endothelial cells. Unexpectedly, gp130-deficient endothelial cells constitutively expressed more CXCL1 in vivo and in vitro, and even more upon stimulation with tumor necrosis factor-α. Mobilization of this increased CXCL1 from intracellular stores to the venular surface triggered β2 integrin–dependent arrest of neutrophils rolling on selectins but impaired intraluminal crawling and transendothelial migration. Superfusing CXCL1 over venules promoted neutrophil migration only after intravenously injecting mAb to CXCL1 to diminish its intravascular function or heparinase to release CXCL1 from endothelial proteoglycans. Remarkably, mice lacking gp130 in endothelial cells had impaired histamine-induced venular permeability, which was restored by injecting anti–P-selectin mAb to prevent neutrophil rolling and arrest. Thus, excessive CXCL1 expression in gp130-deficient endothelial cells augments neutrophil adhesion but hinders migration, most likely by disrupting chemotactic gradients. Our data define a role for endothelial cell gp130 in regulating integrin-dependent adhesion and de-adhesion of neutrophils during inflammation. PMID:24081661

Failure of rabbit neutrophils to secrete endogenous pyrogen when stimulated with staphylococci.

PubMed

Hanson, D F; Murphy, P A; Windle, B E

1980-06-01

Cells obtained from acute peritoneal exudates in rabbits were separated into neutrophil and mononuclear populations by centrifugation on colloidal silica gradients. When these populations were separately incubated in tissue culture medium in the presence of opsonized Staphylococcus epidermidis, endogenous pyrogen was secreted only by the adherent cells of the mononuclear population. Pyrogen production by neutrophils could not have amounted to as much as 1% of the pyrogen produced by macrophages. When mononuclear cells were added back to purified neutrophils, no pyrogen was produced that could not be accounted for by the number of macrophages added. Rabbit blood cells were similarly fractionated on colloidal silica gradients. Again, endogenous pyrogen was made only by the adherent mononuclear population. The neutrophils isolated on these gradients appeared to be morphologically normal and were 85% viable as judged by dye exclusion. They showed normal random motility. Both blood and exudate neutrophils responded chemotactically to N-formyl Met-Leu-Phe, and blood neutrophils responded chemotactically to zymosan-activated serum. Both kinds of neutrophils phagocytosed zymosan particles and both killed opsonized S. epidermidis in a roller tube system. Both blood and exudate neutrophils showed normal superoxide production when stimulated with opsonized zymosan particles. This evidence suggests that macrophages are the only source of endogenous pyrogens, and that pyrogens secreted by cell populations that are rich in neutrophils are to be attributed to the monocytes or macrophages that they contain.

Failure of rabbit neutrophils to secrete endogenous pyrogen when stimulated with staphylococci

PubMed Central

1980-01-01

Cells obtained from acute peritoneal exudates in rabbits were separated into neutrophil and mononuclear populations by centrifugation on colloidal silica gradients. When these populations were separately incubated in tissue culture medium in the presence of opsonized Staphylococcus epidermidis, endogenous pyrogen was secreted only by the adherent cells of the mononuclear population. Pyrogen production by neutrophils could not have amounted to as much as 1% of the pyrogen produced by macrophages. When mononuclear cells were added back to purified neutrophils, no pyrogen was produced that could not be accounted for by the number of macrophages added. Rabbit blood cells were similarly fractionated on colloidal silica gradients. Again, endogenous pyrogen was made only by the adherent mononuclear population. The neutrophils isolated on these gradients appeared to be morphologically normal and were 85% viable as judged by dye exclusion. They showed normal random motility. Both blood and exudate neutrophils responded chemotactically to N-formyl Met-Leu-Phe, and blood neutrophils responded chemotactically to zymosan-activated serum. Both kinds of neutrophils phagocytosed zymosan particles and both killed opsonized S. epidermidis in a roller tube system. Both blood and exudate neutrophils showed normal superoxide production when stimulated with opsonized zymosan particles. This evidence suggests that macrophages are the only source of endogenous pyrogens, and that pyrogens secreted by cell populations that are rich in neutrophils are to be attributed to the monocytes or macrophages that they contain. PMID:6247413

Chemotaxis and auto-chemotaxis of self-propelling artificial droplet swimmers

NASA Astrophysics Data System (ADS)

Jin, Chenyu; Krueger, Carsten; Maass, Corinna

Chemotaxis and auto-chemotaxis are key mechanisms in the dynamics of micro-organisms, e.g. in the acquisition of nutrients and in the communication between individuals, influencing the collective behavior. However, chemical signalling and the natural environment of biological swimmers are generally complex, making them hard to access analytically. Simple experimental systems showing similar features could provide vital insights. We present such a swimmer system, as well as controlled assays to study chemotactic effects quantitatively and reproducibly. In our experiments, we let auto-chemotactic droplet swimmers pass through bifurcating microfluidic channels and record anticorrelations between the branch choices of consecutive droplets. We present an analytical model based on balancing stochastic forces versus a diffusing chemical gradient matching the experimental data. supported by the DFG SPP 1726 ''Microswimmers'' and the MaxSynBio network.

Chemotactic synthetic vesicles: Design and applications in blood-brain barrier crossing.

PubMed

Joseph, Adrian; Contini, Claudia; Cecchin, Denis; Nyberg, Sophie; Ruiz-Perez, Lorena; Gaitzsch, Jens; Fullstone, Gavin; Tian, Xiaohe; Azizi, Juzaili; Preston, Jane; Volpe, Giorgio; Battaglia, Giuseppe

2017-08-01

In recent years, scientists have created artificial microscopic and nanoscopic self-propelling particles, often referred to as nano- or microswimmers, capable of mimicking biological locomotion and taxis. This active diffusion enables the engineering of complex operations that so far have not been possible at the micro- and nanoscale. One of the most promising tasks is the ability to engineer nanocarriers that can autonomously navigate within tissues and organs, accessing nearly every site of the human body guided by endogenous chemical gradients. We report a fully synthetic, organic, nanoscopic system that exhibits attractive chemotaxis driven by enzymatic conversion of glucose. We achieve this by encapsulating glucose oxidase alone or in combination with catalase into nanoscopic and biocompatible asymmetric polymer vesicles (known as polymersomes). We show that these vesicles self-propel in response to an external gradient of glucose by inducing a slip velocity on their surface, which makes them move in an extremely sensitive way toward higher-concentration regions. We finally demonstrate that the chemotactic behavior of these nanoswimmers, in combination with LRP-1 (low-density lipoprotein receptor-related protein 1) targeting, enables a fourfold increase in penetration to the brain compared to nonchemotactic systems.

Chemotactic synthetic vesicles: Design and applications in blood-brain barrier crossing

PubMed Central

Joseph, Adrian; Contini, Claudia; Cecchin, Denis; Nyberg, Sophie; Ruiz-Perez, Lorena; Gaitzsch, Jens; Fullstone, Gavin; Tian, Xiaohe; Azizi, Juzaili; Preston, Jane; Volpe, Giorgio; Battaglia, Giuseppe

2017-01-01

In recent years, scientists have created artificial microscopic and nanoscopic self-propelling particles, often referred to as nano- or microswimmers, capable of mimicking biological locomotion and taxis. This active diffusion enables the engineering of complex operations that so far have not been possible at the micro- and nanoscale. One of the most promising tasks is the ability to engineer nanocarriers that can autonomously navigate within tissues and organs, accessing nearly every site of the human body guided by endogenous chemical gradients. We report a fully synthetic, organic, nanoscopic system that exhibits attractive chemotaxis driven by enzymatic conversion of glucose. We achieve this by encapsulating glucose oxidase alone or in combination with catalase into nanoscopic and biocompatible asymmetric polymer vesicles (known as polymersomes). We show that these vesicles self-propel in response to an external gradient of glucose by inducing a slip velocity on their surface, which makes them move in an extremely sensitive way toward higher-concentration regions. We finally demonstrate that the chemotactic behavior of these nanoswimmers, in combination with LRP-1 (low-density lipoprotein receptor–related protein 1) targeting, enables a fourfold increase in penetration to the brain compared to nonchemotactic systems. PMID:28782037

Coupled effects of chemotaxis and growth on traveling bacterial waves.

PubMed

Yan, Zhifeng; Bouwer, Edward J; Hilpert, Markus

2014-08-01

Traveling bacterial waves are capable of improving contaminant remediation in the subsurface. It is fairly well understood how bacterial chemotaxis and growth separately affect the formation and propagation of such waves. However, their interaction is not well understood. We therefore perform a modeling study to investigate the coupled effects of chemotaxis and growth on bacterial migration, and examine their effects on contaminant remediation. We study the waves by using different initial electron acceptor concentrations for different bacteria and substrate systems. Three types of traveling waves can occur: a chemotactic wave due to the biased movement of chemotactic bacteria resulting from metabolism-generated substrate concentration gradients; a growth/decay/motility wave due to a dynamic equilibrium between bacterial growth, decay and random motility; and an integrated wave due to the interaction between bacterial chemotaxis and growth. Chemotaxis hardly enhances the bacterial propagation if it is too weak to form a chemotactic wave or its wave speed is less than half of the growth/decay/motility wave speed. However, chemotaxis significantly accelerates bacterial propagation once its wave speed exceeds the growth/decay/motility wave speed. When convection occurs, it speeds up the growth/decay/motility wave but slows down or even eliminates the chemotactic wave due to the dispersion. Bacterial survival proves particularly important for bacterial propagation. Therefore we develop a conceptual model to estimate the speed of growth/decay/motility waves. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of tilmicosin on chemotactic, phagocytic, and bactericidal activities of bovine and porcine alveolar macrophages.

PubMed

Brumbaugh, Gordon W; Herman, James D; Clancy, Julianne S; Burden, Kyland I; Barry, Tracie; Simpson, R B; López, Hector Sumano

2002-01-01

To evaluate chemotactic, phagocytic, and bactericidal activities of bovine and porcine alveolar macrophages (AM) exposed to tilmicosin. 12 healthy calves and 12 healthy pigs. Lungs were obtained immediately after euthanasia; AM were collected by means of bronchoalveolar lavage and density gradient centrifugation. Chemotactic activity was evaluated by exposing AM to lipopolysaccharide or macrophage inhibitory peptide during incubation with tilmicosin. Phagocytic activity was evaluated by incubating AM with tilmicosin for 24 hours and then with tilmicosin-resistant Salmonella serotype Typhimurium. Bactericidal activity was evaluated by incubating AM with tilmicosin (0, 10, or 20 microg/ml for bovine AM; 0 or 10 microg/ml or 10 microg/ml but washed free of tilmicosin for porcine AM) and then with Mannheimia haemolytica (bovine AM) or with Actinobacillus pleuropneumoniae or Pasteurella multocida (porcine AM). Tilmicosin had no significant effects on chemotactic or phagocytic activities of bovine or porcine AM. The time-course of bactericidal activity was best described by polynomial equations. Time to cessation of bacterial growth and area under the time versus bacterial number curve were significantly affected by incubation of AM with tilmicosin. Results show that bactericidal activity of bovine and porcine AM was enhanced by tilmicosin, but not in proportion to the reported ability of AM to concentrate tilmicosin intracellularly. With or without exposure to tilmicosin, the time-course of bactericidal activity of bovine AM against M haemolytica and of porcine AM against A pleuropneumoniae or P multocida was too complex to be reduced to a simple linear equation.

Endothelial-derived interleukin-6 induces cancer stem cell motility by generating a chemotactic gradient towards blood vessels.

PubMed

Kim, Hong Sun; Chen, Yu-Chih; Nör, Felipe; Warner, Kristy A; Andrews, April; Wagner, Vivian P; Zhang, Zhaocheng; Zhang, Zhixiong; Martins, Manoela D; Pearson, Alexander T; Yoon, Euisik; Nör, Jacques E

2017-11-21

Recent evidence suggests that the metastatic spread of head and neck squamous cell carcinomas (HNSCC) requires the function of cancer stem cells endowed with multipotency, self-renewal, and high tumorigenic potential. We demonstrated that cancer stem cells reside in perivascular niches and are characterized by high aldehyde dehydrogenase (ALDH) activity and high CD44 expression (ALDH high CD44 high ) in HNSCC. Here, we hypothesize that endothelial cell-secreted interleukin-6 (IL-6) contributes to tumor progression by enhancing the migratory phenotype and survival of cancer stem cells. Analysis of tissue microarrays generated from the invasive fronts of 77 HNSCC patients followed-up for up to 11 years revealed that high expression of IL-6 receptor (IL-6R) (p=0.0217) or co-receptor gp130 (p=0.0422) correlates with low HNSCC patient survival. We observed that endothelial cell-secreted factors induce epithelial to mesenchymal transition (EMT) and enhance invasive capacity of HNSCC cancer stem cells. Conditioned medium from CRISPR/Cas9-mediated IL-6 knockout primary human endothelial cells is less chemotactic for cancer stem cells in a microfluidics-based system than medium from control endothelial cells (p<0.05). Blockade of the IL-6 pathway with a humanized anti-IL-6R antibody (tocilizumab) inhibited endothelial cell-induced motility in vitro and decreased the fraction of cancer stem cells in vivo . Notably, xenograft HNSCC tumors vascularized with IL-6-knockout endothelial cells exhibited slower tumor growth and smaller cancer stem cell fraction. These findings demonstrate that endothelial cell-secreted IL-6 enhances the motility and survival of highly tumorigenic cancer stem cells, suggesting that endothelial cells can create a chemotactic gradient that enables the movement of carcinoma cells towards blood vessels.

Modelling of Dictyostelium discoideum movement in a linear gradient of chemoattractant.

PubMed

Eidi, Zahra; Mohammad-Rafiee, Farshid; Khorrami, Mohammad; Gholami, Azam

2017-11-15

Chemotaxis is a ubiquitous biological phenomenon in which cells detect a spatial gradient of chemoattractant, and then move towards the source. Here we present a position-dependent advection-diffusion model that quantitatively describes the statistical features of the chemotactic motion of the social amoeba Dictyostelium discoideum in a linear gradient of cAMP (cyclic adenosine monophosphate). We fit the model to experimental trajectories that are recorded in a microfluidic setup with stationary cAMP gradients and extract the diffusion and drift coefficients in the gradient direction. Our analysis shows that for the majority of gradients, both coefficients decrease over time and become negative as the cells crawl up the gradient. The extracted model parameters also show that besides the expected drift in the direction of the chemoattractant gradient, we observe a nonlinear dependency of the corresponding variance on time, which can be explained by the model. Furthermore, the results of the model show that the non-linear term in the mean squared displacement of the cell trajectories can dominate the linear term on large time scales.

THE REGULATORY ROLE OF DIVALENT CATIONS IN HUMAN GRANULOCYTE CHEMOTAXIS

PubMed Central

Gallin, John I.; Rosenthal, Alan S.

1974-01-01

Optimal human granulocyte chemotaxis has been shown to require both calcium and magnesium. Exposure of granulocytes to three different chemotactic factors (C5a, kallikrein, and dialyzable transfer factor) yielded a rapid calcium release, depressed calcium uptake, and was associated with a shift of calcium out of the cytoplasm and into a granule fraction. Colchicine, sodium azide, and cytochalasin B, in concentrations that inhibited chemotaxis, also inhibited calcium release while low concentrations of cytochalasin B, which enhanced chemotaxis, also enhanced calcium release. Microtubule assembly was visualized both in cells suspended in C5a without a chemotactic gradient and in cells actively migrating through a Micropore filter. The data suggest microtubule assembly is regulated, at least, in part, by the level of cytoplasmic calcium. It is proposed that asymmetric assembly of microtubules may be instrumental in imparting the net vector of motion during chemotaxis. PMID:4855032

Relation between chemotaxis and consumption of amino acids in bacteria

PubMed Central

Yang, Yiling; M. Pollard, Abiola; Höfler, Carolin; Poschet, Gernot; Wirtz, Markus; Hell, Rüdiger

2015-01-01

Summary Chemotaxis enables bacteria to navigate chemical gradients in their environment, accumulating toward high concentrations of attractants and avoiding high concentrations of repellents. Although finding nutrients is likely to be an important function of bacterial chemotaxis, not all characterized attractants are nutrients. Moreover, even for potential nutrients, the exact relation between the metabolic value of chemicals and their efficiency as chemoattractants has not been systematically explored. Here we compare the chemotactic response of amino acids with their use by bacteria for two well‐established models of chemotactic behavior, E scherichia coli and B acillus subtilis. We demonstrate that in E . coli chemotaxis toward amino acids indeed strongly correlates with their utilization. However, no such correlation is observed for B . subtilis, suggesting that in this case, the amino acids are not followed because of their nutritional value but rather as environmental cues. PMID:25807888

Inferring the Chemotactic Strategy of P. putida and E. coli Using Modified Kramers-Moyal Coefficients

PubMed Central

Hintsche, Marius; Beta, Carsten; Stark, Holger

2017-01-01

Many bacteria perform a run-and-tumble random walk to explore their surrounding and to perform chemotaxis. In this article we present a novel method to infer the relevant parameters of bacterial motion from experimental trajectories including the tumbling events. We introduce a stochastic model for the orientation angle, where a shot-noise process initiates tumbles, and analytically calculate conditional moments, reminiscent of Kramers-Moyal coefficients. Matching them with the moments calculated from experimental trajectories of the bacteria E. coli and Pseudomonas putida, we are able to infer their respective tumble rates, the rotational diffusion constants, and the distributions of tumble angles in good agreement with results from conventional tumble recognizers. We also define a novel tumble recognizer, which explicitly quantifies the error in recognizing tumbles. In the presence of a chemical gradient we condition the moments on the bacterial direction of motion and thereby explore the chemotaxis strategy. For both bacteria we recover and quantify the classical chemotactic strategy, where the tumble rate is smallest along the chemical gradient. In addition, for E. coli we detect some cells, which bias their mean tumble angle towards smaller values. Our findings are supported by a scaling analysis of appropriate ratios of conditional moments, which are directly calculated from experimental data. PMID:28114420

Thermal impulse response and the temperature preference of Escherichia coli

NASA Astrophysics Data System (ADS)

Ryu, William

2010-03-01

From a broad perspective, exposure to environmental temperature changes is a universal condition of living organisms. Escherichia coli is a powerful model system to study how a biochemical network measures and processes thermal information to produce adaptive changes in behavior. E. coli performs thermotaxis, directing its movements to a preferred temperature in spatial thermal gradients. How does the system perform thermotaxis? Where biologically is this analog value of thermal preference stored? Previous studies using populations of cells have shown that E.coli accumulate in spatial thermal gradients, but these experiments did not cleanly separate thermal responses from chemotactic responses. Here we have isolated the thermal behavior by studying the thermal impulse response of single, tethered cells. The motor output of cells was measured in response to small, impulsive increases in temperature, delivered by an infrared laser, over a range of ambient temperature (23 to 43 degrees C). The thermal impulse response at temperatures < 31 degrees C is similar to the chemotactic impulse response: both follow a similar time course, share the same directionality, and show biphasic characteristics. At temperatures > 31 degrees C, some cells show an inverted response, switching from warm- to cold-seeking behavior. The fraction of inverted responses increases nonlinearly with temperature, switching steeply at the preferred temperature of 37 degrees C.

Micromotors Powered by Enzyme Catalysis.

PubMed

Dey, Krishna K; Zhao, Xi; Tansi, Benjamin M; Méndez-Ortiz, Wilfredo J; Córdova-Figueroa, Ubaldo M; Golestanian, Ramin; Sen, Ayusman

2015-12-09

Active biocompatible systems are of great current interest for their possible applications in drug or antidote delivery at specific locations. Herein, we report the synthesis and study of self-propelled microparticles powered by enzymatic reactions and their directed movement in substrate concentration gradient. Polystyrene microparticles were functionalized with the enzymes urease and catalase using a biotin-streptavidin linkage procedure. The motion of the enzyme-coated particles was studied in the presence of the respective substrates, using optical microscopy and dynamic light scattering analysis. The diffusion of the particles was found to increase in a substrate concentration dependent manner. The directed chemotactic movement of these enzyme-powered motors up the substrate gradient was studied using three-inlet microfluidic channel architecture.

Flagellar dynamics reveal the distribution of chemotactic signaling molecule CheY-P in E. coli

NASA Astrophysics Data System (ADS)

Bano, Roshni; Mears, Patrick; Chemla, Yann; Golding, Ido

E. colicells swim in a random walk consisting of ''runs'' - during which the flagella that propel the cell rotate counter-clockwise (CCW) - and ''tumbles''- during which one or more flagella rotate clockwise (CW). The tumbling frequency is modulated by the phosphorylation state of the signaling molecule CheY, which depends on the cell's environment. Phosphorylated CheY (CheY-P) binds to a flagellar motor and engenders a change in rotation state from CCW to CW. Despite advances in methods used to observe chemotactic signaling, it remains a challenge to measure the CheY-P level in cells directly. Here, we used an optical trap assay coupled with fluorescence microscopy to observe the dynamics of fluorescently labelled flagella in individual cells. By measuring the distribution of flagellar states in multi-flagellated cells and using our recent finding that each flagellar motor independently measures the cellular CheY-P concentration, we are able to extract the probability distribution of the CheY-P level in the cell. This analysis reveals the magnitude of fluctuations in chemotactic signaling in the live cell. We further investigate how this CheY-P distribution changes when cells encounter chemical gradients and perform chemotaxis. This work was supported by the National Science Foundation (NSF) through the Centre for Physics of Living Cells (CPLC).

Progesterone from the Cumulus Cells Is the Sperm Chemoattractant Secreted by the Rabbit Oocyte Cumulus Complex

PubMed Central

Guidobaldi, Héctor Alejandro; Teves, María Eugenia; Uñates, Diego Rafael; Anastasía, Agustín; Giojalas, Laura Cecilia

2008-01-01

Sperm chemotaxis in mammals have been identified towards several female sources as follicular fluid (FF), oviduct fluid, and conditioned medium from the cumulus oophorus (CU) and the oocyte (O). Though several substances were confirmed as sperm chemoattractant, Progesterone (P) seems to be the best chemoattractant candidate, because: 1) spermatozoa express a cell surface P receptor, 2) capacitated spermatozoa are chemotactically attracted in vitro by gradients of low quantities of P; 3) the CU cells produce and secrete P after ovulation; 4) a gradient of P may be kept stable along the CU; and 5) the most probable site for sperm chemotaxis in vivo could be near and/or inside the CU. The aim of this study was to verify whether P is the sperm chemoattractant secreted by the rabbit oocyte-cumulus complex (OCC) in the rabbit, as a mammalian animal model. By means of videomicroscopy and computer image analysis we observed that only the CU are a stable source of sperm attractants. The CU produce and secrete P since the hormone was localized inside these cells by immunocytochemistry and in the conditioned medium by enzyme immunoassay. In addition, rabbit spermatozoa express a cell surface P receptor detected by western blot and localized over the acrosomal region by immunocytochemistry. To confirm that P is the sperm chemoattractant secreted by the CU, the sperm chemotactic response towards the OCC conditioned medium was inhibited by three different approaches: P from the OCC conditioned medium was removed with an anti-P antibody, the attractant gradient of the OCC conditioned medium was disrupted by a P counter gradient, and the sperm P receptor was blocked with a specific antibody. We concluded that only the CU but not the oocyte secretes P, and the latter chemoattract spermatozoa by means of a cell surface receptor. Our findings may be of interest in assisted reproduction procedures in humans, animals of economic importance and endangered species. PMID:18725941

Neutrophil adhesion and chemotaxis depend on substrate mechanics

NASA Astrophysics Data System (ADS)

Jannat, Risat A.; Robbins, Gregory P.; Ricart, Brendon G.; Dembo, Micah; Hammer, Daniel A.

2010-05-01

Neutrophil adhesion to the vasculature and chemotaxis within tissues play critical roles in the inflammatory response to injury and pathogens. Unregulated neutrophil activity has been implicated in the progression of numerous chronic and acute diseases such as rheumatoid arthritis, asthma and sepsis. Cell migration of anchorage-dependent cells is known to depend on both chemical and mechanical interactions. Although neutrophil responses to chemical cues have been well characterized, little is known about the effect of underlying tissue mechanics on neutrophil adhesion and migration. To address this question, we quantified neutrophil migration and traction stresses on compliant hydrogel substrates with varying elasticity in a micromachined gradient chamber in which we could apply either a uniform concentration or a precise gradient of the bacterial chemoattractant fMLP. Neutrophils spread more extensively on substrates of greater stiffness. In addition, increasing the stiffness of the substrate leads to a significant increase in the chemotactic index for each fMLP gradient tested. As the substrate becomes stiffer, neutrophils generate higher traction forces without significant changes in cell speed. These forces are often displayed in pairs and focused in the uropod. Increases in the mean fMLP concentration beyond the KD of the receptor lead to a decrease in chemotactic index on all surfaces. Blocking with an antibody against β2-integrins leads to a significant reduction, but not an elimination, of directed motility on stiff materials, but no change in motility on soft materials, suggesting neutrophils can display both integrin-dependent and integrin-independent motility. These findings are critical for understanding how neutrophil migration may change in different mechanical environments in vivo and can be used to guide the design of migration inhibitors that more efficiently target inflammation.

Assays for in vitro monitoring of human airway smooth muscle (ASM) and human pulmonary arterial vascular smooth muscle (VSM) cell migration.

PubMed

Goncharova, Elena A; Goncharov, Dmitry A; Krymskaya, Vera P

2006-01-01

Migration of human pulmonary vascular smooth muscle (VSM) cells contributes to vascular remodeling in pulmonary arterial hypertension and atherosclerosis. Evidence also indicates that, in part, migration of airway smooth muscle (ASM) cells may contribute to airway remodeling associated with asthma. Here we describe migration of VSM and ASM cells in vitro using Transwell or Boyden chamber assays. Because dissecting signaling mechanisms regulating cell migration requires molecular approaches, our protocol also describes how to assess migration of transfected VSM and ASM cells. Transwell or Boyden chamber assays can be completed in approximately 8 h and include plating of serum-deprived VSM or ASM cell suspension on membrane precoated with collagen, migration of cells toward chemotactic gradient and visual (Transwell) or digital (Boyden chamber) analysis of membrane. Although the Transwell assay is easy, the Boyden chamber assay requires hands-on experience; however, both assays are reliable cell-based approaches providing valuable information on how chemotactic and inflammatory factors modulate VSM and ASM migration.

Microchip assays for screening monoclonal antibody product quality.

PubMed

Chen, Xiaoyu; Tang, Kaiyan; Lee, Maximilian; Flynn, Gregory C

2008-12-01

Microchip CE-SDS was evaluated as a high-throughput alternative to conventional CE-SDS for monitoring monoclonal antibody protein quality. A commercial instrument (LabChip) 90) was used to separate dodecyl sulfate coated proteins through a sieving polymer based on the proteins' sizes. Under reducing conditions, the microchip CE-SDS separation was similar to that of conventional CE-SDS, providing reasonable resolution of the non-glycosylated and the glycosylated heavy chains. The fluorescence detection on LabChip 90 using non-covalent fluorescent labeling method was about as sensitive as the 220 nm UV detection used in a conventional CE instrument. A simple glycan typing assay was developed for the reducing microchip CE-SDS format. Antibodies, either pure or in crude cell culture media are treated with Endoglycosidase H, which specifically cleaves the hybrid and high mannose type glycans. A heavy chain migration shift on reducing CE-SDS resulting from the loss of glycan is used to measure the level of high mannose/hybrid type glycans as a percentage of the total glycans. Microchip CE-SDS, under both non-reducing and reducing conditions, can be used in a variety of antibody product screening assays. The microchip analyses provide sufficient resolution and sensitivity for this purpose but on a time scale approximately 70 times faster (41 s versus 50 min per sample) than conventional CE separation under typical operational conditions.

Neutrophil migration under spatially-varying chemoattractant gradient profiles.

PubMed

Halilovic, Iris; Wu, Jiandong; Alexander, Murray; Lin, Francis

2015-01-01

Chemotaxis plays an important role in biological processes such as cancer metastasis, embryogenesis, wound healing, and immune response. Neutrophils are the frontline defenders against invasion of foreign microorganisms into our bodies. To achieve this important immune function, a neutrophil can sense minute chemoattractant concentration differences across its cell body and effectively migrate toward the chemoattractant source. Furthermore, it has been demonstrated in various studies that neutrophils are highly sensitive to changes in the surrounding chemoattractant environments, suggesting the role of a chemotactic memory for processing the complex spatiotemporal chemical guiding signals. Using a microfluidic device, in the present study we characterized neutrophil migration under spatially varying profiles of interleukine-8 gradients, which consist of three spatially ordered regions of a shallow gradient, a steep gradient and a nearly saturated gradient. This design allowed us to examine how neutrophils migrate under different chemoattractant gradient profiles, and how the migratory response is affected when the cell moves from one gradient profile to another in a single experiment. Our results show robust neutrophil chemotaxis in the shallow and steep gradient, but not the saturated gradient. Furthermore, neutrophils display a transition from chemotaxis to flowtaxis when they migrate across the steep gradient interface, and the relative efficiency of this transition depends on the cell's chemotaxis history. Finally, some neutrophils were observed to adjust their morphology to different gradient profiles.

Optical tweezers for studying taxis in parasites

NASA Astrophysics Data System (ADS)

de Thomaz, A. A.; Fontes, A.; Stahl, C. V.; Pozzo, L. Y.; Ayres, D. C.; Almeida, D. B.; Farias, P. M. A.; Santos, B. S.; Santos-Mallet, J.; Gomes, S. A. O.; Giorgio, S.; Feder, D.; Cesar, C. L.

2011-04-01

In this work we present a methodology to measure force strengths and directions of living parasites with an optical tweezers setup. These measurements were used to study the parasites chemotaxis in real time. We observed behavior and measured the force of: (i) Leishmania amazonensis in the presence of two glucose gradients; (ii) Trypanosoma cruzi in the vicinity of the digestive system walls, and (iii) Trypanosoma rangeli in the vicinity of salivary glands as a function of distance. Our results clearly show a chemotactic behavior in every case. This methodology can be used to study any type of taxis, such as chemotaxis, osmotaxis, thermotaxis, phototaxis, of any kind of living microorganisms. These studies can help us to understand the microorganism sensory systems and their response function to these gradients.

Reconstitution of a physical complex between the N-formyl chemotactic peptide receptor and G protein. Inhibition by pertussis toxin-catalyzed ADP ribosylation.

PubMed

Bommakanti, R K; Bokoch, G M; Tolley, J O; Schreiber, R E; Siemsen, D W; Klotz, K N; Jesaitis, A J

1992-04-15

Photoaffinity-labeled N-formyl chemotactic peptide receptors from human neutrophils solubilized in octyl glucoside exhibit two forms upon sucrose density gradient sedimentation, with apparent sedimentation coefficients of approximately 4 and 7 S. The 7 S form can be converted to the 4 S form by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) with an EC50 of approximately 20 nM, suggesting that the 7 S form may represent a physical complex of the receptor with endogenous G protein (Jesaitis, A. J., Tolley, J. O., Bokoch, G. M., and Allen, R. A. (1989) J. Cell Biol. 109, 2783-2790). To probe the nature of the 7 S form, we reconstituted the 7 S form from the 4 S form by adding purified G protein. The 4 S form, obtained by solubilizing GTP gamma S-treated neutrophil plasma membranes, was incubated with purified (greater than 95%) Gi protein from bovine brain (containing both Gi alpha 1 and Gi alpha 2) or with neutrophil G protein (Gn), and formation of the 7 S complex was analyzed on sucrose density gradients. The EC50 of 7 S complex formation induced by the two G proteins was 70 +/- 25 and 170 +/- 40 nM for Gn and Gi, respectively. No complexation was measurable when bovine transducin (Gt) was used up to 30 times the EC50 for Gn. The EC50 for Gi was the same for receptors, obtained from formyl peptide-stimulated or unstimulated cells. The addition of 10 microM GTP gamma S to the reconstituted 7 S complex caused a complete revision of the receptor to the 4 S form, and anti-Gi peptide antisera immunosedimented the 7 S form. ADP-ribosylation of Gi prevented formation of the 7 S form even at 20 times the concentration of unribosylated Gi normally used to attain 50% conversion to the 7 S form. These observations suggest that the 7 S species is a physical complex containing N-formyl chemotactic peptide receptor and G protein.

Rabbit polymorphonuclear leukocytes do not secrete endogenous pyrogens or interleukin 1 when stimulated by endotoxin, polyinosine:polycytosine, or muramyl dipeptide.

PubMed

Windle, B E; Murphy, P A; Cooperman, S

1983-03-01

Rabbit polymorphonuclear leukocytes were purified from rabbit blood by centrifugation on colloidal silica gradients followed by sedimentation in 4% Ficoll. The purified neutrophils had normal random motility, responded to chemotactic stimuli, phagocytosed zymosan particles, made superoxide, and phagocytosed and killed bacteria. However, they did not secret endogenous pyrogens either spontaneously or in response to stimulation with endotoxin, polyinosine:polycytosine, or muramyl dipeptide. Macrophages isolated on the same gradients secreted some pyrogen spontaneously and secreted considerably more in response to the same three stimuli. This evidence reinforces the idea that macrophages are the only source of endogenous pyrogens, and that pyrogens secreted by cell populations that are rich in neutrophils are to be attributed to the monocytes or macrophages that the cell populations contain.

Current characteristics of λ-DNA molecules/polystyrene nanoparticles in TBE buffer solution through micro/nanofluidic capillaries under DC electric field

NASA Astrophysics Data System (ADS)

Duan, Yifei; Zhao, Wei; Xue, Jing; Sun, Dan; Wang, Kaige; Wang, Guiren; Li, Junjie; Bai, Jintao; Gu, Changzhi

2017-03-01

In practical applications of biochips and bio-sensors, electrokinetic mechanisms are commonly employed to manipulate single bio-molecules and analyze their characteristics. To accurately and flexibly control the movement of single-molecule within micro/nanofluidic channels which are the basic components of Lab-chips, the current signals in micro/nanocapillaries filled with solutions of DNA molecules or polystyrene (PS) nanoparticles are systematically studied. Experimental results indicate that the current response along the micro/nanocapillaries can be significantly influenced by the diameter of the capillaries and the pH value of the solutions. Specifically, when there is only a pure (TBE) solution, the electric conductance does not monotonically decrease with decreasing the diameter of the capillaries, but slightly increases with decreasing the capillary diameter. When λ-DNA molecules or PS nanoparticles are added into the TBE buffer, the size effect on the electric conductance of the solutions are quite different. Although in the former, the electric conductance behaves differently from that in the pure TBE solution and decreases with the decreasing diameter, in the latter, the change is similar to that in the pure TBE solution. Besides, an abnormal ‘falling’ of the electric conductance is observed in a capillary with diameter of 200 nm. The investigation will significantly enhance the understanding on the electric properties of the solutions of biomolecules and particles in micro/nanofluidics. This is especially helpful for designing functional Lab-chip devices.

Collective gradient sensing: fundamental bounds, cluster mechanics, and cell-to-cell variability

NASA Astrophysics Data System (ADS)

Camley, Brian

Many eukaryotic cells chemotax, sensing and following chemical gradients. However, experiments have shown that even under conditions when single cells do not chemotax, small clusters may still follow a gradient. Similar collective motion is also known to occur in response to gradients in substrate stiffness or electric potential (collective durotaxis or galvanotaxis). How can cell clusters sense a gradient that individual cells ignore? I discuss possible ``collective guidance'' mechanisms underlying this motion, where individual cells measure the mean value of the attractant, but need not measure its gradient to give rise to directional motility for a cell cluster. I show that the collective guidance hypothesis can be directly tested by looking for strong orientational effects in pairs of cells chemotaxing. Collective gradient sensing also has a new wrinkle in comparison to single-cell chemotaxis: to accurately determine a gradient direction, a cluster must integrate information from cells with highly variable properties. When is cell-to-cell variation a limiting factor in sensing accuracy? I provide some initial answers, and discuss how cell clusters can sense gradients in a way that is robust to cell-to-cell variation. Interestingly, these strategies may depend on the cluster's mechanics; I develop a bound that links the cluster's chemotactic accuracy and its rheology. This suggests that in some circumstances, mechanical transitions (e.g. unjamming) can control tactic accuracy. Work supported by NIH Grant No. P01 GM078586, NIH Grant No. F32GM110983.

Role of chemotaxis in the transport of bacteria through saturated porous media

USGS Publications Warehouse

Ford, R.M.; Harvey, R.W.

2007-01-01

Populations of chemotactic bacteria are able to sense and respond to chemical gradients in their surroundings and direct their migration toward increasing concentrations of chemicals that they perceive to be beneficial to their survival. It has been suggested that this phenomenon may facilitate bioremediation processes by bringing bacteria into closer proximity to the chemical contaminants that they degrade. To determine the significance of chemotaxis in these processes it is necessary to quantify the magnitude of the response and compare it to other groundwater processes that affect the fate and transport of bacteria. We present a systematic approach toward quantifying the chemotactic response of bacteria in laboratory scale experiments by starting with simple, well-defined systems and gradually increasing their complexity. Swimming properties of individual cells were assessed from trajectories recorded by a tracking microscope. These properties were used to calculate motility and chemotaxis coefficients of bacterial populations in bulk aqueous media which were compared to experimental results of diffusion studies. Then effective values of motility and chemotaxis coefficients in single pores, pore networks and packed columns were analyzed. These were used to estimate the magnitude of the chemotactic response in porous media and to compare with dispersion coefficients reported in the field. This represents a compilation of many studies over a number of years. While there are certainly limitations with this approach for ultimately quantifying motility and chemotaxis in granular aquifer media, it does provide insight into what order of magnitude responses are possible and which characteristics of the bacteria and media are expected to be important. ?? 2006 Elsevier Ltd. All rights reserved.

Multimodal chemo-magnetic control of self-propelling microbots

NASA Astrophysics Data System (ADS)

Singh, Amit Kumar; Dey, Krishna Kanti; Chattopadhyay, Arun; Mandal, Tapas Kumar; Bandyopadhyay, Dipankar

2014-01-01

We report a controlled migration of an iron nanoparticle (FeNP) coated polymer micromotor. The otherwise diffusive motion of the motor was meticulously directed through an in situ pH-gradient and an external magnetic field. The self-propulsion owing to the asymmetric catalytic decomposition of peroxide fuel was directed through a pH gradient imposed across the motor-surface, while the magnetic field induced an external control on the movement and the speed of the motor. Interestingly, the sole influence of the pH gradient could move the motor as high as ~25 body lengths per second, which was further magnified by the external assistance from the magnetic field. Applying a magnetic field against the pH directed motion helped in the quantitative experimental estimation of the force-field required to arrest the chemotactic migration. The influence of the coupled internal and external fields could halt, steer or reverse the direction the motor inside a microchannel, rotate the motor around a target, and deliver the motor to a cluster of cells. This study showcases a multimodal chemical-magnetic field regulated migration of micro-machines for sensing, transport, and delivery inside a fluidic environment.We report a controlled migration of an iron nanoparticle (FeNP) coated polymer micromotor. The otherwise diffusive motion of the motor was meticulously directed through an in situ pH-gradient and an external magnetic field. The self-propulsion owing to the asymmetric catalytic decomposition of peroxide fuel was directed through a pH gradient imposed across the motor-surface, while the magnetic field induced an external control on the movement and the speed of the motor. Interestingly, the sole influence of the pH gradient could move the motor as high as ~25 body lengths per second, which was further magnified by the external assistance from the magnetic field. Applying a magnetic field against the pH directed motion helped in the quantitative experimental estimation of the force-field required to arrest the chemotactic migration. The influence of the coupled internal and external fields could halt, steer or reverse the direction the motor inside a microchannel, rotate the motor around a target, and deliver the motor to a cluster of cells. This study showcases a multimodal chemical-magnetic field regulated migration of micro-machines for sensing, transport, and delivery inside a fluidic environment. Electronic supplementary information (ESI) available: Scanning electron microscopy, transmission electron microscopy, X-ray diffraction pattern, vibrating sample magnetometry (VSM) hysteresis loop of freshly prepared FeNP coated micromotor and movies of micromotor motion. See DOI: 10.1039/c3nr05294j

Azospirillum brasilense Chemotaxis Depends on Two Signaling Pathways Regulating Distinct Motility Parameters

PubMed Central

Mukherjee, Tanmoy; Kumar, Dhivya; Burriss, Nathan; Xie, Zhihong

2016-01-01

ABSTRACT The genomes of most motile bacteria encode two or more chemotaxis (Che) systems, but their functions have been characterized in only a few model systems. Azospirillum brasilense is a motile soil alphaproteobacterium able to colonize the rhizosphere of cereals. In response to an attractant, motile A. brasilense cells transiently increase swimming speed and suppress reversals. The Che1 chemotaxis pathway was previously shown to regulate changes in the swimming speed, but it has a minor role in chemotaxis and root surface colonization. Here, we show that a second chemotaxis system, named Che4, regulates the probability of swimming reversals and is the major signaling pathway for chemotaxis and wheat root surface colonization. Experimental evidence indicates that Che1 and Che4 are functionally linked to coordinate changes in the swimming motility pattern in response to attractants. The effect of Che1 on swimming speed is shown to enhance the aerotactic response of A. brasilense in gradients, likely providing the cells with a competitive advantage in the rhizosphere. Together, the results illustrate a novel mechanism by which motile bacteria utilize two chemotaxis pathways regulating distinct motility parameters to alter movement in gradients and enhance the chemotactic advantage. IMPORTANCE Chemotaxis provides motile bacteria with a competitive advantage in the colonization of diverse niches and is a function enriched in rhizosphere bacterial communities, with most species possessing at least two chemotaxis systems. Here, we identify the mechanism by which cells may derive a significant chemotactic advantage using two chemotaxis pathways that ultimately regulate distinct motility parameters. PMID:27068592

Azospirillum brasilense Chemotaxis Depends on Two Signaling Pathways Regulating Distinct Motility Parameters.

PubMed

Mukherjee, Tanmoy; Kumar, Dhivya; Burriss, Nathan; Xie, Zhihong; Alexandre, Gladys

2016-06-15

The genomes of most motile bacteria encode two or more chemotaxis (Che) systems, but their functions have been characterized in only a few model systems. Azospirillum brasilense is a motile soil alphaproteobacterium able to colonize the rhizosphere of cereals. In response to an attractant, motile A. brasilense cells transiently increase swimming speed and suppress reversals. The Che1 chemotaxis pathway was previously shown to regulate changes in the swimming speed, but it has a minor role in chemotaxis and root surface colonization. Here, we show that a second chemotaxis system, named Che4, regulates the probability of swimming reversals and is the major signaling pathway for chemotaxis and wheat root surface colonization. Experimental evidence indicates that Che1 and Che4 are functionally linked to coordinate changes in the swimming motility pattern in response to attractants. The effect of Che1 on swimming speed is shown to enhance the aerotactic response of A. brasilense in gradients, likely providing the cells with a competitive advantage in the rhizosphere. Together, the results illustrate a novel mechanism by which motile bacteria utilize two chemotaxis pathways regulating distinct motility parameters to alter movement in gradients and enhance the chemotactic advantage. Chemotaxis provides motile bacteria with a competitive advantage in the colonization of diverse niches and is a function enriched in rhizosphere bacterial communities, with most species possessing at least two chemotaxis systems. Here, we identify the mechanism by which cells may derive a significant chemotactic advantage using two chemotaxis pathways that ultimately regulate distinct motility parameters. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Sperm as microswimmers - navigation and sensing at the physical limit

NASA Astrophysics Data System (ADS)

Kaupp, Ulrich B.; Alvarez, Luis

2016-11-01

Many cells and microorganisms have evolved a motility apparatus to explore their surroundings. For guidance, these biological microswimmers rely on physical and chemical cues that are transduced by cellular pathways into directed movement - a process called taxis. Only few biological microswimmers have been studied as detailed as sperm from sea urchins. Sperm and eggs are released into the seawater. To enhance the chances of fertilization, eggs release chemical factors - called chemoattractants - that establish a chemical gradient and, thereby, guide sperm to the egg. Sea urchin sperm constitute a unique model system for understanding cell navigation at every level: from molecules to cell behaviours. We will outline the chemotactic signalling pathway of sperm from the sea urchin Arbacia punctulata and discuss how signalling controls navigation in a chemical gradient. Finally, we discuss recent insights into sperm chemotaxis in three dimensions (3D).

Rabbit polymorphonuclear leukocytes do not secrete endogenous pyrogens or interleukin 1 when stimulated by endotoxin, polyinosine:polycytosine, or muramyl dipeptide.

PubMed Central

Windle, B E; Murphy, P A; Cooperman, S

1983-01-01

Rabbit polymorphonuclear leukocytes were purified from rabbit blood by centrifugation on colloidal silica gradients followed by sedimentation in 4% Ficoll. The purified neutrophils had normal random motility, responded to chemotactic stimuli, phagocytosed zymosan particles, made superoxide, and phagocytosed and killed bacteria. However, they did not secret endogenous pyrogens either spontaneously or in response to stimulation with endotoxin, polyinosine:polycytosine, or muramyl dipeptide. Macrophages isolated on the same gradients secreted some pyrogen spontaneously and secreted considerably more in response to the same three stimuli. This evidence reinforces the idea that macrophages are the only source of endogenous pyrogens, and that pyrogens secreted by cell populations that are rich in neutrophils are to be attributed to the monocytes or macrophages that the cell populations contain. PMID:6601619

Single particle train ordering in microchannel based on inertial and vortex effects

NASA Astrophysics Data System (ADS)

Fan, Liang-Liang; Yan, Qing; Zhe, Jiang; Zhao, Liang

2018-06-01

A new microfluidic device for microparticle focusing and ordering in a single particle train is reported. The particle focusing and ordering are based on inertial and vortex effects in a microchannel with a series of suddenly contracted and widely expanded structures on one side. In the suddenly contracted regions, particles located near the contracted structures are subjected to a strong wall-effect lift force and momentum-change-induced inertial force due to the highly curved trajectory, migrating to the straight wall. A horizontal vortex is generated downstream of the contracted structure, which prevents the particle from getting close to the wall. In the widely expanded regions, the streamline is curved and no vortex is generated. The shear-gradient lift force and the momentum-change-induced inertial force are dominant for particle lateral migration, driving particles towards the wall of the expanded structures. Eventually, particles are focused and ordered in a single particle train by the combination effects of the inertial forces and the vortex. In comparison with other single-stream particle focusing methods, this device requires no sheath flow, is easy for fabrication and operation, and can work over a wide range of Reynolds numbers from 19.1–142.9. The highly ordered particle chain could be potentially utilized in a variety of lab-chip applications, including micro-flow cytometer, imaging and droplet-based cell entrapment.

Deficiency of the Chemotactic Factor Inactivator in Human Sera with α1-Antitrypsin Deficiency

PubMed Central

Ward, Peter A.; Talamo, Richard C.

1973-01-01

As revealed by appropriate fractionation procedures, human serum deficient in α1-antitrypsin (α1-AT) is also deficient in the naturally occurring chemotactic factor inactivator. These serum donors had severe pulmonary emphysema. Serum from patients with clinically similar pulmonary disease, but with presence of α1-AT in the serum, showed no such deficiency of the chemotactic factor inactivator. When normal human serum and α1-AT-deficient human sera are chemotactically activated by incubation with immune precipitates, substantially more chemotactic activity is generated in α1-AT-deficient serum. These data indicate that in α1-AT-deficient serum there is an imbalance in the generation and control of chemotactic factors. It is suggested that the theory regarding development of pulmonary emphysema in patients lacking the α1-antitrypsin in their serum should be modified to take into account a deficiency of the chemotactic factor inactivator. PMID:4683887

Urease Plays an Important Role in the Chemotactic Motility of Helicobacter pylori in a Viscous Environment

PubMed Central

Nakamura, Hiroki; Yoshiyama, Hironori; Takeuchi, Hiroaki; Mizote, Tomoko; Okita, Kiwamu; Nakazawa, Teruko

1998-01-01

Helicobacter pylori exhibits chemotactic responses to urea, flurofamide, acetohydroxamic acid, and sodium bicarbonate. In buffer, the chemotactic activities of a urease-positive strain were higher than those of the isogenic urease-negative strain. Moreover, the chemotactic activities of the urease-positive strain were increased in a viscous solution containing 3% polyvinylpyrrolidone, whereas those of the urease-negative mutant were not. These results are in accordance with the fact that the mutant strain did not show swarming in motility agar regardless of having flagella. Incubation of the wild-type strain with flurofamide resulted in partial inhibition of the chemotactic activities in the viscous solution. In addition, incubation with acetohydroxamic acid, a low-molecular-weight, diffusible urease inhibitor, resulted in complete loss of chemotactic activity in the viscous solution. The inhibition of the chemotactic activity by urease inhibitors paralleled the inhibition of urease. The chemotactic activity of H. pylori was also inhibited by the proton carrier carbonyl cyanide m-chlorophenylhydrazone, showing that H. pylori utilizes proton motive force for motility. These results indicate that cytoplasmic urease plays an important role in the chemotactic motility of H. pylori under a condition that mimics the ecological niche of the bacterium, the gastric mucous layer. PMID:9746586

Urease plays an important role in the chemotactic motility of Helicobacter pylori in a viscous environment.

PubMed

Nakamura, H; Yoshiyama, H; Takeuchi, H; Mizote, T; Okita, K; Nakazawa, T

1998-10-01

Helicobacter pylori exhibits chemotactic responses to urea, flurofamide, acetohydroxamic acid, and sodium bicarbonate. In buffer, the chemotactic activities of a urease-positive strain were higher than those of the isogenic urease-negative strain. Moreover, the chemotactic activities of the urease-positive strain were increased in a viscous solution containing 3% polyvinylpyrrolidone, whereas those of the urease-negative mutant were not. These results are in accordance with the fact that the mutant strain did not show swarming in motility agar regardless of having flagella. Incubation of the wild-type strain with flurofamide resulted in partial inhibition of the chemotactic activities in the viscous solution. In addition, incubation with acetohydroxamic acid, a low-molecular-weight, diffusible urease inhibitor, resulted in complete loss of chemotactic activity in the viscous solution. The inhibition of the chemotactic activity by urease inhibitors paralleled the inhibition of urease. The chemotactic activity of H. pylori was also inhibited by the proton carrier carbonyl cyanide m-chlorophenylhydrazone, showing that H. pylori utilizes proton motive force for motility. These results indicate that cytoplasmic urease plays an important role in the chemotactic motility of H. pylori under a condition that mimics the ecological niche of the bacterium, the gastric mucous layer.

Analysis of bacterial migration; 1: Numerical solution of balance equation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frymier, P.D.; Ford, R.M.; Cummings, P.T.

1994-04-01

Chemotaxis describes the ability of motile bacteria to bias their motion in the direction of increasing gradients of chemicals, usually energy sources, known as attractants. In experimental studies of the migration of chemotactic bacteria, 1-D phenomenological cell balance equations have been used to quantitatively analyze experimental observations. While attractive for their simplicity and the ease of solution, they are limited in the strict mathematical sense to the situation in which individual bacteria are confined to motion in one dimension and respond to attractant gradients in one dimension only. Recently, Ford and Cummings (1992) reduced the general 3-D cell balance equationmore » of Alt (1980) to obtain an equation describing the migration of a bacterial population in response to a 1-D attractant gradient. Solutions of this equation for single gradients of attractants are compared to those of 1-D balance equations, results from cellular dynamics simulations, and experimental data from the authors' laboratory for E. coli responding to [alpha]-methylaspartate. The authors also investigate two aspects of the experimentally derived expression for the tumbling probability: the effect of different models for the down-gradient swimming behavior of the bacteria and the validity of ignoring the temporal derivative of the attractant concentration.« less

Coarse graining Escherichia coli chemotaxis: from multi-flagella propulsion to logarithmic sensing.

PubMed

Curk, Tine; Matthäus, Franziska; Brill-Karniely, Yifat; Dobnikar, Jure

2012-01-01

Various sensing mechanisms in nature can be described by the Weber-Fechner law stating that the response to varying stimuli is proportional to their relative rather than absolute changes. The chemotaxis of bacteria Escherichia coli is an example where such logarithmic sensing enables sensitivity over large range of concentrations. It has recently been experimentally demonstrated that under certain conditions E. coli indeed respond to relative gradients of ligands. We use numerical simulations of bacteria in food gradients to investigate the limits of validity of the logarithmic behavior. We model the chemotactic signaling pathway reactions, couple them to a multi-flagella model for propelling and take the effects of rotational diffusion into account to accurately reproduce the experimental observations of single cell swimming. Using this simulation scheme we analyze the type of response of bacteria subject to exponential ligand profiles and identify the regimes of absolute gradient sensing, relative gradient sensing, and a rotational diffusion dominated regime. We explore dependance of the swimming speed, average run time and the clockwise (CW) bias on ligand variation and derive a small set of relations that define a coarse grained model for bacterial chemotaxis. Simulations based on this coarse grained model compare well with microfluidic experiments on E. coli diffusion in linear and exponential gradients of aspartate.

Nutrient chemotaxis suppression of a diffusive instability in bacterial colony dynamics

NASA Astrophysics Data System (ADS)

Arouh, Scott; Levine, Herbert

2000-07-01

Bacteria grown on a semisolid agar surface have been observed to form branching patterns as the colony envelope propagates outward. The fundamental cause of this instability relates to the need for limited nutrient to diffuse towards the colony. Here, we investigate the effect on this instability of allowing the bacteria to move chemotactically in response to the nutrient gradient. Our results show that this additional effect has a tendency to suppress the instability. Our calculations are done within the context of a simple ``cutoff'' model of colony dynamics, but presumably remain valid for more complex and hence more realistic approaches.

Chemotaxis of basophils by lymphocyte-dependent and lymphocyte-independent mechanisms.

PubMed

Ward, P A; Dvorak, H F; Cohen, S; Yoshida, T; Data, R; Selvaggio, S S

1975-05-01

Guine pigs basophils obtained from blood or bone marrow have been studied for their chemotactic responsiveness. Chemotactic factors for basophils include a substance (lymphokine) present in culture fluids from antigen-stimulated lymphocytes, a material generated in zymosan-activated guinea pig serum, a C5 cleavage factor, and a bacterial factor. When compared with homologous neutrophils and monocytes, basophils respond most rapidly to a chemotactic stimulus. The lymphokine basophil chemotactic factor is physicochemically similar to the previously described monocyte chemotactic factor but appears to be distinct from it as well as MIF and neutrophil chemotactic factor present in the same fluids, Part of the evidence for this is the ability to detect basophil chemotactic factor in the absence of other lymphokine activities under appropriate experimental conditions. More evidence, specifically relating to the monocyte factor, is that monocytes can adsorb basophil chemotactic activity but not vice versa. This latter observation may have implications for the mechanism whereby the accumulation of basophils is controlled and limited in vivo. In addition, it was noted that specific antigen could also suppress basophil chemotaxis. Although the mechanism of this phenomenon is unclear, it could serve as a second means by which basophil accumulation may be controlled in the intact animal. Taken together, these observations provide further definition of the chemotactic behavior of basophils in general, and underscore some of the ways in which lymphocytes can influence basophils through lymphokine-dependent mechanisms.

Cell–cell communication enhances the capacity of cell ensembles to sense shallow gradients during morphogenesis

PubMed Central

Ellison, David; Mugler, Andrew; Brennan, Matthew D.; Lee, Sung Hoon; Huebner, Robert J.; Shamir, Eliah R.; Woo, Laura A.; Kim, Joseph; Amar, Patrick; Nemenman, Ilya; Ewald, Andrew J.; Levchenko, Andre

2016-01-01

Collective cell responses to exogenous cues depend on cell–cell interactions. In principle, these can result in enhanced sensitivity to weak and noisy stimuli. However, this has not yet been shown experimentally, and little is known about how multicellular signal processing modulates single-cell sensitivity to extracellular signaling inputs, including those guiding complex changes in the tissue form and function. Here we explored whether cell–cell communication can enhance the ability of cell ensembles to sense and respond to weak gradients of chemotactic cues. Using a combination of experiments with mammary epithelial cells and mathematical modeling, we find that multicellular sensing enables detection of and response to shallow epidermal growth factor (EGF) gradients that are undetectable by single cells. However, the advantage of this type of gradient sensing is limited by the noisiness of the signaling relay, necessary to integrate spatially distributed ligand concentration information. We calculate the fundamental sensory limits imposed by this communication noise and combine them with the experimental data to estimate the effective size of multicellular sensory groups involved in gradient sensing. Functional experiments strongly implicated intercellular communication through gap junctions and calcium release from intracellular stores as mediators of collective gradient sensing. The resulting integrative analysis provides a framework for understanding the advantages and limitations of sensory information processing by relays of chemically coupled cells. PMID:26792522

Exploring Inflammatory Disease Drug Effects on Neutrophil Function

PubMed Central

Wu, Xiaojie; Kim, Donghyuk; Young, Ashlyn T.; Haynes, Christy L.

2014-01-01

Neutrophils are critical inflammatory cells; thus, it is important to characterize the effects of drugs on neutrophil function in the context of inflammatory diseases. Herein, chemically guided neutrophil migration, known as chemotaxis, is studied in the context of drug treatment at the single cell level using a microfluidic platform, complemented by cell viability assays and calcium imaging. Three representative drugs known to inhibit surface receptor expression, signaling enzyme activity, and the elevation of intracellular Ca2+ levels, each playing a significant role in neutrophil chemotactic pathways, are used to examine the in vitro drug effects on cellular behaviors. The microfluidic device establishes a stable concentration gradient of chemokines across a cell culture chamber so that neutrophil migration can be monitored under various drug-exposure conditions. Different time- and concentration-dependent regulatory effects were observed by comparing the motility, polarization, and effectiveness of neutrophil chemotaxis in response to the three drugs. Viability assays revealed distinct drug capabilities in reducing neutrophil viability while calcium imaging clarified the role of Ca2+ in the neutrophil chemotactic pathway. This study provides mechanistic insight into the drug effects on neutrophil function, facilitating comparison of current and potential pharmaceutical approaches. PMID:24946254

Squid-derived chitin oligosaccharides are a chemotactic signal during colonization by Vibrio fischeri.

PubMed

Mandel, Mark J; Schaefer, Amy L; Brennan, Caitlin A; Heath-Heckman, Elizabeth A C; Deloney-Marino, Cindy R; McFall-Ngai, Margaret J; Ruby, Edward G

2012-07-01

Chitin, a polymer of N-acetylglucosamine (GlcNAc), is noted as the second most abundant biopolymer in nature. Chitin serves many functions for marine bacteria in the family Vibrionaceae ("vibrios"), in some instances providing a physical attachment site, inducing natural genetic competence, and serving as an attractant for chemotaxis. The marine luminous bacterium Vibrio fischeri is the specific symbiont in the light-emitting organ of the Hawaiian bobtail squid, Euprymna scolopes. The bacterium provides the squid with luminescence that the animal uses in an antipredatory defense, while the squid supports the symbiont's nutritional requirements. V. fischeri cells are harvested from seawater during each host generation, and V. fischeri is the only species that can complete this process in nature. Furthermore, chitin is located in squid hemocytes and plays a nutritional role in the symbiosis. We demonstrate here that chitin oligosaccharides produced by the squid host serve as a chemotactic signal for colonizing bacteria. V. fischeri uses the gradient of host chitin to enter the squid light organ duct and colonize the animal. We provide evidence that chitin serves a novel function in an animal-bacterial mutualism, as an animal-produced bacterium-attracting synomone.

Macrophages influence a competition of contact guidance and chemotaxis for fibroblast alignment in a fibrin gel coculture assay.

PubMed

Bromberek, B A; Enever, P A J; Shreiber, D I; Caldwell, M D; Tranquillo, R T

2002-05-01

Rat dermal fibroblasts were dispersed initially in the outer shell of a fibrin gel sphere, while the inner core either was devoid of cells or contained peritoneal exudate cells (primarily macrophages), thereby mimicking the inflammatory phase of wound healing. The fibroblasts compacted floating fibrin microspheres over time. In the absence of macrophages, the initial distribution of fibroblasts (only in the shell) induced circumferential alignment of fibrin fibrils via compaction of the shell relative to the core. The aligned fibrils created a contact guidance field, which was manifested by strong circumferential alignment of the fibroblasts. However, in the presence of macrophages, the fibroblasts exhibited more radial alignment despite the simultaneous contact guidance field in the circumferential direction associated with compaction. This was attributed to a chemotactic gradient emanating from the core due to a putative factor(s) released by the macrophages. The presence of a radial chemotactic stimulus was supported by the finding of even greater radial alignment when fibrin microspheres were embedded in an agarose-fibrin gel that abolished compaction and consequently the contact guidance field. Our assay permits the simulation of tissue morphogenetic processes that involve cell guidance phenomena and tractional restructuring of the extracellular matrix.

Evolutionarily conserved coupling of adaptive and excitable networks mediates eukaryotic chemotaxis

NASA Astrophysics Data System (ADS)

Tang, Ming; Wang, Mingjie; Shi, Changji; Iglesias, Pablo A.; Devreotes, Peter N.; Huang, Chuan-Hsiang

2014-10-01

Numerous models explain how cells sense and migrate towards shallow chemoattractant gradients. Studies show that an excitable signal transduction network acts as a pacemaker that controls the cytoskeleton to drive motility. Here we show that this network is required to link stimuli to actin polymerization and chemotactic motility and we distinguish the various models of chemotaxis. First, signalling activity is suppressed towards the low side in a gradient or following removal of uniform chemoattractant. Second, signalling activities display a rapid shut off and a slower adaptation during which responsiveness to subsequent test stimuli decline. Simulations of various models indicate that these properties require coupled adaptive and excitable networks. Adaptation involves a G-protein-independent inhibitor, as stimulation of cells lacking G-protein function suppresses basal activities. The salient features of the coupled networks were observed for different chemoattractants in Dictyostelium and in human neutrophils, suggesting an evolutionarily conserved mechanism for eukaryotic chemotaxis.

Meisoindigo, but not its core chemical structure indirubin, inhibits zebrafish interstitial leukocyte chemotactic migration.

PubMed

Ye, Baixin; Xiong, Xiaoxing; Deng, Xu; Gu, Lijuan; Wang, Qiongyu; Zeng, Zhi; Gao, Xiang; Gao, Qingping; Wang, Yueying

2017-12-01

Inflammatory disease is a big threat to human health. Leukocyte chemotactic migration is required for efficient inflammatory response. Inhibition of leukocyte chemotactic migration to the inflammatory site has been shown to provide therapeutic targets for treating inflammatory diseases. Our study was designed to discover effective and safe compounds that can inhibit leukocyte chemotactic migration, thus providing possible novel therapeutic strategy for treating inflammatory diseases. In this study, we used transgenic zebrafish model (Tg:zlyz-EGFP line) to visualize the process of leukocyte chemotactic migration. Then, we used this model to screen the hit compound and evaluate its biological activity on leukocyte chemotactic migration. Furthermore, western blot analysis was performed to evaluate the effect of the hit compound on the AKT or ERK-mediated pathway, which plays an important role in leukocyte chemotactic migration. In this study, using zebrafish-based chemical screening, we identified that the hit compound meisoindigo (25 μM, 50 μM, 75 μM) can significantly inhibit zebrafish leukocyte chemotactic migration in a dose-dependent manner (p = 0.01, p = 0.0006, p < 0.0001). Also, we found that meisoindigo did not affect the process of leukocyte reverse migration (p = 0.43). Furthermore, our results unexpectedly showed that indirubin, the core structure of meisoindigo, had no significant effect on zebrafish leukocyte chemotactic migration (p = 0.6001). Additionally, our results revealed that meisoindigo exerts no effect on the Akt or Erk-mediated signalling pathway. Our results suggest that meisoindigo, but not indirubin, is effective for inhibiting leukocyte chemotactic migration, thus providing a potential therapeutic agent for treating inflammatory diseases.

Diagnostic and Prognostic Values of Monocyte Chemotactic Protein-1 in Ascitic Fluid of Patients with Spontaneous Bacterial Peritonitis.

PubMed

El-Toukhy, Naglaa; Emam, Sherin M

2016-06-01

Spontaneous bacterial peritonitis (SBP) is a severe complication in cirrhotics with ascites. Monocyte chemotactic protien-1 (MCP-1) is a chemotactic factor for monocytes/macrophages, and it activates lymphocytes and neutrophils during infection. This study aimed to evaluate the role of MPC-1 in the pathogenesis of SBP and assess its prognostic value and correlation to disease severity. The study included ninety patients with liver cirrhosis and ascites. Patients were divided into 2 groups: Group I including 45 ascetic patients with SBP (polymorph nuclear cell count (PMN) >= 250 cell/mm3 in ascitic fluid), and Group II including 45 ascetic patients without SBP. Assessment of the severity of liver cirrhosis was done using the modified Child-Pugh and model for end stage liver disease (MELD) scores. Ascetic fluid samples were subjected to total leucocytic count and differential, albumin, protein, glucose, and serum-ascetic albumin gradient analysis Ascetic fluid levels of (MCP-1was measured by ELISA. Higher level was detected in patients with SBP as compared to those without SBP. The number of polymorph nuclear cell count (PMN) >= 250 cell/mm3 in ascitic fluid) was used as gold standard for diagnosis of SBP. The diagnosis sensitivity and specificity of MCP level test were 86.7% and 95.4% respectively at cutoff of122.5ng/ml with accuracy 91%. MCP-1 level showed positive significant correlation with TLC, PMN leucocytes and MELD score. In conclusion, ascitic fluid MCP-1 level could be a reliable test for diagnosis of SBP, and could be used as a prognostic marker due to its positive correlation with the severity of liver disease. Copyright© by the Egyptian Association of Immunologists.

Chemotactic droplet swimmers in complex geometries

NASA Astrophysics Data System (ADS)

Jin, Chenyu; Hokmabad, Babak V.; Baldwin, Kyle A.; Maass, Corinna C.

2018-02-01

Chemotaxis1 and auto-chemotaxis are key mechanisms in the dynamics of micro-organisms, e.g. in the acquisition of nutrients and in the communication between individuals, influencing the collective behaviour. However, chemical signalling and the natural environment of biological swimmers are generally complex, making them hard to access analytically. We present a well-controlled, tunable artificial model to study chemotaxis and autochemotaxis in complex geometries, using microfluidic assays of self-propelling oil droplets in an aqueous surfactant solution (Herminghaus et al 2014 Soft Matter 10 7008-22 Krüger et al 2016 Phys. Rev. Lett. 117). Droplets propel via interfacial Marangoni stresses powered by micellar solubilisation. Moreover, filled micelles act as a chemical repellent by diffusive phoretic gradient forces. We have studied these chemotactic effects in a series of microfluidic geometries, as published in Jin et al (2017 Proc. Natl Acad. Sci. 114 5089-94): first, droplets are guided along the shortest path through a maze by surfactant diffusing into the maze from the exit. Second, we let auto-chemotactic droplet swimmers pass through bifurcating microfluidic channels and record anticorrelations between the branch choices of consecutive droplets. We present an analytical Langevin model matching the experimental data. In a previously unpublished experiment, pillar arrays of variable sizes and shapes provide a convex wall interacting with the swimmer and, in the case of attachment, bending its trajectory and forcing it to revert to its own trail. We observe different behaviours based on the interplay of wall curvature and negative autochemotaxis, i.e. no attachment for highly curved interfaces, stable trapping at large pillars, and a narrow transition region where negative autochemotaxis makes the swimmers detach after a single orbit.

Bacteria Interactions with Dying Diatoms

NASA Astrophysics Data System (ADS)

Smriga, S.; Juarez, G.; Fernandez, V.; Stocker, R.

2016-02-01

Dying phytoplankton are surrounded by microscale gradients of dissolved organic matter (DOM) that can attract bacteria. These 'phycospheres' may impact the trophic transfer of DOM in the marine microbial food web and enable the growth of bacterial populations, yet these effects remain poorly quantified particularly in relation to the physiological state of the phytoplankton. We dissected phycosphere interactions at unprecedented spatial and temporal resolution using the model diatom Thalassiosira weissflogii and the bacterium Marinobacter adhaerans. Diatom stress was stimulated by addition of polyunsaturated aldehyde (PUA) and both diatom and bacterial responses were captured via time-lapse fluorescence microscopy. We found that stressed diatoms underwent lysis 10-15 h after PUA treatment. Coordinated with the timing of this transition into phytodetritus, wild-type Marinobacter accumulated via chemotaxis near the diatoms immediately following lysis. In contrast, at lysis there was no accumulation of either a non-chemotactic or a non-motile mutant of Marinobacter, pointing to behavioral rather than demographic responses as drivers for the accumulation. Despite the lack of response, non-chemotactic as well as non-swimming bacterial cells that by chance attached to or were located near (<30 µm) stressed diatoms experienced more growth than cells further afield. Growth within the phycosphere was even greater after diatom lysis. Through quantification at the microscale, these results reveal that chemotaxis may precede rapid bacterial attachment to stressed and dying diatoms and may be integral to the microbial colonization of new phytodetritus during phytoplankton blooms and bloom collapses in coastal ecosystems. Even while chemotactic cells retain a growth advantage given their ability to sense and respond to lysis events, phycosphere DOM provides growth benefits to both motile and non-motile taxa that become attached to or happen to be co-located with new phytodetrital particles, thus likely influencing the composition of particle-attached microbial communities.

Dendritic Cell Migration Toward CCL21 Gradient Requires Functional Cx43

PubMed Central

Ruez, Richard; Dubrot, Juan; Zoso, Alice; Bacchetta, Marc; Molica, Filippo; Hugues, Stéphanie; Kwak, Brenda R.; Chanson, Marc

2018-01-01

Dendritic cells (DCs) travel through lymphatic vessels to transport antigens and present them to T cells in lymph nodes. DCs move directionally toward lymphatics by virtue of their CCR7 and a CCL21 chemotactic gradient. We evaluated in vivo and in bone marrow-derived dendritic cells (BMDCs) whether the gap junction protein Cx43 contributes to CCL21/CCR7-dependent DC migration in wild-type (WT) mice, heterozygous (Cx43+/−) mice and mice expressing a truncated form of Cx43 lacking its regulatory C-terminus (Cx43K258/−). In a model of flank skin inflammation, we found that the recruitment of myeloid DCs (mDCs) to skin draining lymph nodes was reduced in Cx43K258/− mice as compared to WT and Cx43+/− mice. In addition, the migration of Cx43K258/− BMDCs toward CCL21 was abolished in an in vitro chemotactic assay while it was only reduced in Cx43+/− cells. Both mutant genotypes showed defects in the directionality of BMDC migration as compared to WT BMDCs. No difference was found between the three populations of BMDCs in terms of expression of surface markers (CD11c, CD86, CD80, CD40, MHC-II, and CCR7) after differentiation and TLR activation. Finally, examination of the CCR7-induced signaling pathways in BMDCs revealed normal receptor-induced mobilization of intracellular Ca2+. These results demonstrate that full expression of an intact Cx43 is critical to the directionality and rate of DC migration, which may be amenable to regulation of the immune response. PMID:29636699

Contact guidance is cell cycle-dependent.

PubMed

Pourfarhangi, Kamyar Esmaeili; De La Hoz, Edgar Cardenas; Cohen, Andrew R; Gligorijevic, Bojana

2018-09-01

Cancer cell migration is essential for metastasis, during which cancer cells move through the tumor and reach the blood vessels. In vivo , cancer cells are exposed to contact guidance and chemotactic cues. Depending on the strength of such cues, cells will migrate in a random or directed manner. While similar cues may also stimulate cell proliferation, it is not clear whether cell cycle progression affects migration of cancer cells and whether this effect is different in random versus directed migration. In this study, we tested the effect of cell cycle progression on contact guided migration in 2D and 3D environments, in the breast carcinoma cell line, FUCCI-MDA-MB-231. The results were quantified from live cell microscopy images using the open source lineage editing and validation image analysis tools (LEVER). In 2D, cells were placed inside 10 μ m-wide microchannels to stimulate contact guidance, with or without an additional chemotactic gradient of the soluble epidermal growth factor. In 3D, contact guidance was modeled by aligned collagen fibers. In both 2D and 3D, contact guidance was cell cycle-dependent, while the addition of the chemo-attractant gradient in 2D increased cell velocity and persistence in directionally migrating cells, regardless of their cell cycle phases. In both 2D and 3D contact guidance, cells in the G1 phase of the cell cycle outperformed cells in the S/G2 phase in terms of migration persistence and instantaneous velocity. These data suggest that in the presence of contact guidance cues in vivo , breast carcinoma cells in the G1 phase of the cell cycle may be more efficient in reaching the neighboring vasculature.

A diffusion based long-range and steady chemical gradient generator on a microfluidic device for studying bacterial chemotaxis

NASA Astrophysics Data System (ADS)

Murugesan, Nithya; Singha, Siddhartha; Panda, Tapobrata; Das, Sarit K.

2016-03-01

Studies on chemotaxis in microfluidics device have become a major area of research to generate physiologically similar environment in vitro. In this work, a novel micro-fluidic device has been developed to study chemo-taxis of cells in near physiological condition which can create controllable, steady and long-range chemical gradients using various chemo-effectors in a micro-channel. Hydrogels like agarose, collagen, etc, can be used in the device to maintain exclusive diffusive flux of various chemical species into the micro-channel under study. Variations of concentrations and flow rates of Texas Red dextran in the device revealed that an increase in the concentration of the dye in the feed from 6 to 18 μg ml-1, causes a steeper chemical gradient in the device, whereas the flow rate of the dye has practically no effect on the chemical gradient in the device. This observation confirms that a diffusion controlled chemical gradient is generated in the micro-channel. Chemo-taxis of E. coli cells were studied under the steady gradient of a chemo-attractant and a chemo-repellent separately in the same chemical gradient generator. For sorbitol and NiSO4·6H2O, the bacterial cells exhibit a steady distribution in the micro channel after 1 h and 30 min, respectively. From the distribution of bacterial population chemo-tactic strength of the chemo-effectors was estimated for E. coli. In a long microfluidic channel, migration behavior of bacterial cells under diffusion controlled chemical gradient showed chemotaxis, random movement, aggregation, and concentration dependent reverse chemotaxis.

THE RELATIONSHIP OF THE CHEMOTACTIC BEHAVIOR OF THE COMPLEMENT-DERIVED FACTORS, C3a, C5a, AND C567, AND A BACTERIAL CHEMOTACTIC FACTOR TO THEIR ABILITY TO ACTIVATE THE PROESTERASE 1 OF RABBIT POLYMORPHONUCLEAR LEUKOCYTES

PubMed Central

Becker, Elmer L.

1972-01-01

The inhibition profiles obtained when a series of p-nitrophenyl ethyl alkylphosphonates and of p-nitrophenyl ethyl chloroalkylphosphonates were used to interfere with the chemotactic activity of polymorphonuclear leukocytes stimulated by C3a, C5a, and bacterial factor were the same as found previously when C567 was the chemotactic agent. This indicates that as in the chemotactic activity induced by C567, an obligatory step in the chemotaxis caused by C3a, C5a, and bacterial factor is the activation of proesterase 1 of the rabbit polymorphonuclear leukocyte. C5a and C3a activate proesterase 1 of peripheral blood polymophonuclear leukocytes as measured by the increase of acetyl DL-phenylalanine β-naphthyl esterase activity. Attempts to detect in a like manner the proesterase 1 of the same leukocytes using bacterial factor under varying circumstances have consistently failed. It is concluded that bacterial factor, for unknown reasons, is unable to activate proesterase 1 to the same extent as the complement-derived chemotactic factors. The hypothesis of there being a quantitative difference in the ability of bacterial factor to activate proesterase 1 compared with the complement-derived factors explains the previous observations that bacterial factor can not deactivate to itself or to the complement-derived factors, although these latter factors can deactivate to themselves, to each other, and to the bacterial factor. The quantitative difference in the ability of bacterial factor to activate proesterase 1 compared to the complement-derived factors is also associated with and explains the finding that the maximal chemotactic activity attainable when bacterial factor is the chemotactic agent is distinctly less than that obtained using either C3a, C5a, or C567. These results indicate that the activation of proesterase 1 is a general requirement for the chemotactic activity of rabbit polymorphonuclear leukocytes with known macromolecular chemotactic agents and suggest that under several different circumstances the level of chemotactic activity attained is related to the degree of such activation. PMID:4551218

Enhanced neutrophil chemotactic activity after bronchial challenge in subjects with grain dust-induced asthma.

PubMed

Park, H S; Jung, K S

1998-03-01

There have been few reports suggesting involvement of neutrophils in induction of bronchoconstriction after inhalation of grain dust. To understand the role of neutrophils in pathogenesis of grain dust-induced asthma. We observed serum neutrophil chemotactic activity during grain dust-bronchoprovocation tests in six asthmatic subjects with positive bronchial challenges (group I). They were compared with those of six symptomatic subjects from the same workplace with negative bronchial challenges (group II). After grain dust inhalation, serum neutrophil chemotactic activity significantly increased at 30 minutes (P = .028), and then decreased to baseline level at 240 minutes (P = .028) in five subjects of group I having isolated early asthmatic responses. Enhanced neutrophil chemotactic activity was persistent for up to 240 minutes in one asthmatic subject having both early and late asthmatic responses. There was, however, no significant change in serum neutrophil chemotactic activity during bronchial challenges in subjects of group II. Pre-incubation of sera with anti-interleukin-8 (IL-8) antibody did not affect the neutrophil chemotactic activity results of group I subjects. These results suggest that enhanced neutrophil chemotactic activity distinct from IL-8 may contribute to significant bronchoconstriction induced by grain dust.

Nicotine is Chemotactic for Neutrophils and Enhances Neutrophil Responsiveness to Chemotactic Peptides

NASA Astrophysics Data System (ADS)

Totti, Noel; McCusker, Kevin T.; Campbell, Edward J.; Griffin, Gail L.; Senior, Robert M.

1984-01-01

Neutrophils contribute to chronic bronchitis and pulmonary emphysema associated with cigarette smoking. Nicotine was found to be chemotactic for human neutrophils but not monocytes, with a peak activity at ~ 31 micromolar. In lower concentrations (comparable to those in smokers' plasma), nicotine enhanced the response of neutrophils to two chemotactic peptides. In contrast to most other chemoattractants for neutrophils, however, nicotine did not affect degranulation or superoxide production. Nicotine thus may promote inflammation and consequent lung injury in smokers.

Development path and current status of the NANIVID: a new device for cancer cell studies

NASA Astrophysics Data System (ADS)

Raja, Waseem Khan; Padgen, Michael R.; Williams, James K.; Wyckoff, Jeffrey; Condeelis, John; Castracane, James

2011-02-01

Cancer cells create a unique microenvironment in vivo which enables migration to distant organs. To better understand the tumor microenvironment, special tools and devices are required to monitor the interactions between different cell types and the effects of particular chemical gradients. This study presents the design and optimization of a new, versatile chemotaxis device called the NANIVID (NANo IntraVital Device). The device is fabricated using BioMEMS techniques and consists of etched and bonded Pyrex substrates, a soluble factor reservoir, fluorescent tracking beads and a microelectrode array for cell quantification. The reservoir contains a customized hydrogel blend loaded with EGF which diffuses out of the hydrogel to create a chemotactic gradient. This reservoir sustains a steady release of growth factor into the surrounding environment for many hours and establishes a concentration gradient that attracts specific cells to the device. In addition to a cell collection tool, the NANIVID can be modified to act as a delivery vehicle for the local generation of alternate soluble factor gradients to initiate controlled changes to the microenvironment such as hypoxia, ECM stiffness and etc. The focus of this study is to design and optimize the new device for wide ranging studies of breast cancer cell dynamics in vitro and ultimately, implantation for in vivo work.

Evaluation and optimisation of preparative semi-automated electrophoresis systems for Illumina library preparation.

PubMed

Quail, Michael A; Gu, Yong; Swerdlow, Harold; Mayho, Matthew

2012-12-01

Size selection can be a critical step in preparation of next-generation sequencing libraries. Traditional methods employing gel electrophoresis lack reproducibility, are labour intensive, do not scale well and employ hazardous interchelating dyes. In a high-throughput setting, solid-phase reversible immobilisation beads are commonly used for size-selection, but result in quite a broad fragment size range. We have evaluated and optimised the use of two semi-automated preparative DNA electrophoresis systems, the Caliper Labchip XT and the Sage Science Pippin Prep, for size selection of Illumina sequencing libraries. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel dioxygenation product of arachidonic acid possesses potent chemotactic activity for human polymorphonuclear leukocytes.

PubMed

Shak, S; Perez, H D; Goldstein, I M

1983-12-25

We have found that a novel dioxygenation product of arachidonic acid, 8(S),15(S)-dihydroxy-5,11-cis-9,13-trans-eicosatetraenoic acid (8,15-diHETE), possesses chemotactic activity for human polymorphonuclear leukocytes comparable to that of leukotriene B4. Authentic 8,15-diHETE, identified by gas chromatography-mass spectrometry, was prepared by treating arachidonic acid with soybean lipoxygenase and was purified by reverse-phase high performance liquid chromatography. Using a "leading front" assay, 8,15-diHETE exhibited significant chemotactic activity at a concentration of 5.0 ng/ml. Maximum chemotactic activity was observed at a concentration of 30 ng/ml. The 8,15-diHETE generated by mixed human leukocytes after stimulation with arachidonic acid and the calcium ionophore, A23187, exhibited quantitatively similar chemotactic activity. Two synthetic all-trans conjugated isomers of 8,15-diHETE, however, were not chemotactic at concentrations up to 500 ng/ml. In contrast to its potent chemotactic activity, 8,15-diHETE (at concentrations up to 10 micrograms/ml) was relatively inactive with respect to its ability to provoke either degranulation or generation of superoxide anion radicals by cytochalasin B-treated leukocytes. Both leukotriene B4 and 8,15-diHETE may be important mediators of inflammation.

Dimensionless Analysis Applied to Bacterial Chemotaxis towards NAPL Contaminants

NASA Astrophysics Data System (ADS)

Wang, X.; GAO, B.; Zhong, W.; Kihaule, K. S.; Ford, R.

2017-12-01

The use of chemotactic bacteria in bioremediation may improve the efficiency and decrease the cost of restoration, which means it has the potential to address environmental problems caused by oil spills. However, most previous studies were focused at the laboratory-scale and there lacks a formalism that can use these laboratory-scale results as input to evaluate the relative importance of chemotaxis at the field scale. In this study, a dimensionless equation is formulated to solve this problem. First, the main influential factors were extracted based on previous researches in environmental bioremediation and then five sets of dimensionless numbers were obtained according to Buckingham theory. After collecting basic parameter values and supplementary calculations to determine the concentration gradient of the chemoattractant, all dimensionless numbers were calculated and categorized into two types, those that were sensitive to chemotaxis or those to groundwater velocity. The bacteria ratio (BR), defined as the ratio of maximum bacteria concentration to its original value, was correlated with a combination of dimensionless numbers to yield, BR=cP1-0.085P20.329P30.1P4-0.098. For a bacterial ratio greater than one, the bioremediation strategy based on chemotaxis is expected to be effective, and chemotactic bacteria are expected to accumulate around NAPL contaminant sources efficiently.

Development path and current status of the NANIVID: a new device for cancer cell studies.

PubMed

Raja, Waseem Khan; Padgen, Michael R; Williams, James K; Gertler, Frank B; Wyckoff, Jeffrey B; Condeelis, John S; Castracane, James

2012-03-29

Cancer cells create a unique microenvironment in vivo that enables migration to distant organs. To better understand the tumor micro-environment, special tools and devices are required to monitor the interactions between different cell types and the effects of particular chemical gradients. Our study presents the design and optimization of a versatile chemotaxis device, the nano-intravital device (NANIVID), which consists of etched and bonded glass substrates that create a soluble factor reservoir. The device contains a customized hydrogel blend that is loaded with epidermal growth factor (EGF), which diffuses from the outlet to create a chemotactic gradient that can be sustained for many hours in order to attract specific cells to the device. A microelectrode array is under development for quantification of cell collection and will be incorporated into future device generations. Additionally, the NANIVID can be modified to generate gradients of other soluble factors in order to initiate controlled changes to the microenvironment including the induction of hypoxia, manipulation of extracellular matrix stiffness, etc. The focus of the article is to present the design and optimization of the device towards wide ranging applications of cancer cell dynamics in vitro and, ultimately, implantation for in vivo investigations.

Chemotactic activity from rabbit peritoneal neutrophils. Lack of identity with N-acetyl-DL-phenylalanine beta-napthyl esterase.

PubMed

Tsung, P K; Showell, H J; Kegeles, S W; Becker, E L

1976-08-12

The chemotactic and N-acetyl-DL-phenylalanine beta-naphthyl esterase activities of rabbit peritoneal neutrophils are separable from each other by both DEAE cellulose and Sephadex G-100 column chromatography. Partially purified esterase obtained from DEAE-cellulose chromatography had molecular weight of 70 000. However, the partially purified fraction contained chemotactic activities with major activity in molecular weight of 28000 and minor activities in the molecular weights of 45000, 21900, 14500 and 10500. Esterase activity is inhibited by 10(-7) M p-nitrophenylethyl-5-chloropentylphosphonate but chemotactic activity is not.

Interplay between chemotaxis and contact inhibition of locomotion determines exploratory cell migration

PubMed Central

Lin, Benjamin; Yin, Taofei; Wu, Yi I.; Inoue, Takanari; Levchenko, Andre

2015-01-01

Directed cell migration in native environments is influenced by multiple migratory cues. These cues may include simultaneously occurring attractive soluble growth factor gradients and repulsive effects arising from cell-cell contact, termed contact inhibition of locomotion (CIL). How single cells reconcile potentially conflicting cues remains poorly understood. Here we show that a dynamic crosstalk between epidermal growth factor (EGF) mediated chemotaxis and CIL guide metastatic breast cancer cell motility, whereby cells become progressively insensitive to CIL in a chemotactic input-dependent manner. This balance is determined via integration of protrusion-enhancing signaling from EGF gradients and protrusion-suppressing signaling induced by CIL, mediated in part through EphB. Our results further suggest that EphB and EGF signaling inputs control protrusion formation by converging onto regulation of phosphatidylinositol 3-kinase (PI3K). We propose that this intricate interplay may enhance the spread of loose cell ensembles in pathophysiological conditions such as cancer, and possibly other physiological settings. PMID:25851023

In vitro quantitative analysis of Salmonella typhimurium preference for amino acids secreted by human breast tumor

NASA Astrophysics Data System (ADS)

Choi, Eunpyo; Maeng, Bohee; Lee, Jae-hun; Chang, Hyung-kwan; Park, Jungyul

2016-12-01

Bacterial therapies have been paid significant attentions by their ability to penetrate deep into the solid tumor tissue and its propensity to naturally accumulate in tumors of living animals. Understanding the actual mechanism for bacteria to target the tumor is therapeutically crucial but is poorly understood. We hypothesized that amino acids released from the specific tumors induced bacteria to those tumors and the experiments for chemotactic response of bacteria toward the cancer secreting amino acids was then performed by using the diffusion based multiple chemical gradient generator constructed by in situ self-assembly of microspheres. The quantitative analysis was carried out by comparison of intensity using green fluorescent protein (GFP) tagged Salmonella typhimurium ( S. typhimurium) in the gradient generator, which showed the clear preference to the released amino acids, especially from breast cancer patients. The understanding chemotaxis toward the cancer secreting amino acids is essential for controlling S. typhimurium targeting in tumors and will allow for the development of bacterial therapies.

First-instar western corn rootworm (Coleoptera: chrysomelidae) response to carbon dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strnad, S.P.; Bergman, M.K.; Fulton, W.C.

1986-08-01

Responses of first-instar western corn rootworm to CO/sub 2/ and N/sub 2/ gas gradients were studied in a laboratory test arena. Number of larvae reaching the gas source, number of turns toward and away from the gas source, larval velocity, and number of turns per cm traveled were recorded. Larvae exhibited a positive chemotactic response to CO/sub 2/ but not N/sub 2/ or air. There was no indication that a kinesis of any type was involved because velocities and turning rates were not significantly different among treatments. Results indicate that newly hatched larve may use CO/sub 2/ to locate cornmore » roots.« less

Comparison of neutrophil functions between two strains of inbred mice.

PubMed

Zhang, Xiaohuan; Zhao, Sainan; Sun, Luping; Li, Wenqing; Glogauer, Michael; Hu, Yan

2016-12-01

In this study, differences between two strains of inbred mice in aspects of neutrophil function, namely Rac1 expression, chemotaxis, nicotinamide adenine dinucleotide phosphate oxidase activity and formation of neutrophil extracellular traps (NETs), were determined. Neutrophils from CBA/CaH mice exhibited weaker Rac1 expression and a slower chemotactic gradient than BALB/c mice. Furthermore, PMA- or fMLP-stimulated neutrophils from CBA/CaH mice generated much less superoxide and NETs than similarly stimulated neutrophils from BALB/c mice. These findings suggest that neutrophils from BALB/c mice are functionally more efficient than those from CBA/CaH mice. © 2016 The Societies and John Wiley & Sons Australia, Ltd.

Decreased numbers of chemotactic factor receptors in chronic neutropenia with defective chemotaxis: spontaneous recovery from the neutrophil abnormalities during early childhood

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yasui, K.; Yamazaki, M.; Miyagawa, Y.

Childhood chronic neutropenia with decreased numbers of chemotactic factor receptors as well as defective chemotaxis was first demonstrated in an 8-month-old girl. Chemotactic factor receptors on neutrophils were assayed using tritiated N-formyl-methionyl-leucyl-phenylalanine (/sup 3/H-FMLP). The patient's neutrophils had decreased numbers of the receptors: numbers of the receptors were 20,000 (less than 3 SD) as compared with those of control cells of 52,000 +/- 6000 (mean +/- SD) (n = 10). The neutropenia disappeared spontaneously by 28 months of age parallel with the improvement of chemotaxis and increase in numbers of chemotactic factor receptors. These results demonstrate a transient decrease ofmore » neutrophil chemotactic factor receptors as one of the pathophysiological bases of a transient defect of neutrophil chemotaxis in this disorder.« less

An intracellular signaling hierarchy determines direction of migration in opposing chemotactic gradients.

PubMed

Heit, Bryan; Tavener, Samantha; Raharjo, Eko; Kubes, Paul

2002-10-14

Neutrophils must follow both endogenous and bacterial chemoattractant signals out of the vasculature and through the interstitium to arrive at a site of infection. By necessity, in the setting of multiple chemoattractants, the neutrophils must prioritize, favoring end target chemoattractants (e.g., fMLP and C5a) emanating from the site of infection over intermediary endogenous chemoattractants (e.g., IL-8 and LTB4) encountered en route to sites of infection. In this study, we propose a hierarchical model of two signaling pathways mediating the decision-making process of the neutrophils, which allows end target molecules to dominate over intermediary chemoattractants. In an under agarose assay, neutrophils predominantly migrated toward end target chemoattractants via p38 MAPK, whereas intermediary chemoattractant-induced migration was phosphoinositide 3-kinase (PI3K)/Akt dependent. When faced with competing gradients of end target and intermediary chemoattractants, Akt activation was significantly reduced within neutrophils, and the cells migrated preferentially toward end target chemoattractants even at 1/1,000th that of intermediary chemoattractants. End target molecules did not require chemotactic properties, since the p38 MAPK activator, LPS, also inhibited Akt and prevented migration to intermediary chemoattractants. p38 MAPK inhibitors not only reversed this hierarchy, such that neutrophils migrated preferentially toward intermediary chemoattractants, but also allowed neutrophils to be drawn out of a local end target chemoattractant environment and toward intermediary chemoattractants unexpectedly in an exaggerated (two- to fivefold) fashion. This was entirely related to significantly increased magnitude and duration of Akt activation. Finally, end target chemoattractant responses were predominantly Mac-1 dependent, whereas nondominant chemoattractants used primarily LFA-1. These data provide support for a two pathway signaling model wherein the end target chemoattractants activate p38 MAPK, which inhibits intermediary chemoattractant-induced PI3K/Akt pathway, establishing an intracellular signaling hierarchy.

Chemotactic activity of cotyledons for mononuclear leukocytes related to occurrence of retained placenta in dexamethasone induced parturition in cattle.

PubMed

Benedictus, L; Jorritsma, R; Knijn, H M; Vos, P L A M; Koets, A P

2011-09-15

Induction of parturition with glucocorticosteroids in cattle is used for research purposes, in diseased or injured pregnant cows, and as a management tool to time parturition. A negative side effect of induction of parturition with glucocorticosteroids is the high incidence of retained placenta that occurs after these calvings. Reaction of the maternal immune system against the 'foreign' foetal membranes contributes to the breakdown of the foetal-maternal attachment. Several studies indicate that failure of this immune assisted detachment increases the occurrence of retained placenta. We hypothesized that retained placenta occurring after induction of parturition with glucocorticosteroids is caused by failure of immune assisted detachment of the foetal membranes. The chemotactic activity of cotyledons for mononuclear leukocytes was used as a parameter to see whether immune assisted detachment of the foetal membranes had occurred. Cotyledons were collected from spontaneously calving non-retained placenta cows and from dexamethasone induced non-retained placenta and retained placenta cows. The study showed that the chemotactic activity of cotyledons for mononuclear leukocytes was lower (P < 0.001) in cotyledons obtained from retained placenta cows in which parturition was induced with dexamethasone compared to the chemotactic activity of cotyledons obtained from spontaneously calving non-retained placenta cows, whereas the chemotactic activity of cotyledons obtained from induced non-retained placenta cows was not lower (P = 0.10) than the chemotactic activity of cotyledons obtained from spontaneously calving non-retained placenta cows. We concluded that induction of parturition with dexamethasone causes a failure of immune assisted detachment of the foetal membranes and the accompanying release of chemotactic factors. As a result, the chemotactic activity of cotyledons for mononuclear leukocytes is lower in induced retained placenta cows than in cotyledons from non-retained placenta cows in which successful immune assisted detachment of the foetal membranes occurs. Copyright © 2011 Elsevier Inc. All rights reserved.

Many-body dynamics of chemically propelled nanomotors

NASA Astrophysics Data System (ADS)

Colberg, Peter H.; Kapral, Raymond

2017-08-01

The collective behavior of chemically propelled sphere-dimer motors made from linked catalytic and noncatalytic spheres in a quasi-two-dimensional confined geometry is studied using a coarse-grained microscopic dynamical model. Chemical reactions at the catalytic spheres that convert fuel to product generate forces that couple to solvent degrees of freedom as a consequence of momentum conservation in the microscopic dynamics. The collective behavior of the many-body system is influenced by direct intermolecular interactions among the motors, chemotactic effects due to chemical gradients, hydrodynamic coupling, and thermal noise. Segregation into high and low density phases and globally homogeneous states with strong fluctuations are investigated as functions of the motor characteristics. Factors contributing to this behavior are discussed in the context of active Brownian models.

T cell costimulation by chemokine receptors.

PubMed

Molon, Barbara; Gri, Giorgia; Bettella, Monica; Gómez-Moutón, Concepción; Lanzavecchia, Antonio; Martínez-A, Carlos; Mañes, Santos; Viola, Antonella

2005-05-01

Signals mediated by chemokine receptors may compete with T cell receptor stop signals and determine the duration of T cell-antigen-presenting cell interactions. Here we show that during T cell stimulation by antigen-presenting cells, T cell chemokine receptors coupled to G(q) and/or G(11) protein were recruited to the immunological synapse by a G(i)-independent mechanism. When chemokine receptors were sequestered at the immunological synapse, T cells became insensitive to chemotactic gradients, formed more stable conjugates and finally responded with enhanced proliferation and cytokine production. We suggest that chemokine receptor trapping at the immunological synapse enhances T cell activation by improving T cell-antigen-presenting cell attraction and impeding the 'distraction' of successfully engaged T cells by other chemokine sources.

Precision Sensing by Two Opposing Gradient Sensors: How Does Escherichia coli Find its Preferred pH Level?

PubMed Central

Hu, Bo; Tu, Yuhai

2013-01-01

It is essential for bacteria to find optimal conditions for their growth and survival. The optimal levels of certain environmental factors (such as pH and temperature) often correspond to some intermediate points of the respective gradients. This requires the ability of bacteria to navigate from both directions toward the optimum location and is distinct from the conventional unidirectional chemotactic strategy. Remarkably, Escherichia coli cells can perform such a precision sensing task in pH taxis by using the same chemotaxis machinery, but with opposite pH responses from two different chemoreceptors (Tar and Tsr). To understand bacterial pH sensing, we developed an Ising-type model for a mixed cluster of opposing receptors based on the push-pull mechanism. Our model can quantitatively explain experimental observations in pH taxis for various mutants and wild-type cells. We show how the preferred pH level depends on the relative abundance of the competing sensors and how the sensory activity regulates the behavioral response. Our model allows us to make quantitative predictions on signal integration of pH and chemoattractant stimuli. Our study reveals two general conditions and a robust push-pull scheme for precision sensing, which should be applicable in other adaptive sensory systems with opposing gradient sensors. PMID:23823247

Coupled excitable Ras and F-actin activation mediates spontaneous pseudopod formation and directed cell movement

PubMed Central

van Haastert, Peter J. M.; Keizer-Gunnink, Ineke; Kortholt, Arjan

2017-01-01

Many eukaryotic cells regulate their mobility by external cues. Genetic studies have identified >100 components that participate in chemotaxis, which hinders the identification of the conceptual framework of how cells sense and respond to shallow chemical gradients. The activation of Ras occurs during basal locomotion and is an essential connector between receptor and cytoskeleton during chemotaxis. Using a sensitive assay for activated Ras, we show here that activation of Ras and F-actin forms two excitable systems that are coupled through mutual positive feedback and memory. This coupled excitable system leads to short-lived patches of activated Ras and associated F-actin that precede the extension of protrusions. In buffer, excitability starts frequently with Ras activation in the back/side of the cell or with F-actin in the front of the cell. In a shallow gradient of chemoattractant, local Ras activation triggers full excitation of Ras and subsequently F-actin at the side of the cell facing the chemoattractant, leading to directed pseudopod extension and chemotaxis. A computational model shows that the coupled excitable Ras/F-actin system forms the driving heart for the ordered-stochastic extension of pseudopods in buffer and for efficient directional extension of pseudopods in chemotactic gradients. PMID:28148648

The effects of oral consumption of selenium nanoparticles on chemotactic and respiratory burst activities of neutrophils in comparison with sodium selenite in sheep.

PubMed

Kojouri, Gholam Ali; Sadeghian, Sirous; Mohebbi, Abdonnaser; Mokhber Dezfouli, Mohammad Reza

2012-05-01

The present study was designed to compare the effects of nano-selenium and of sodium selenite on the chemotactic and respiratory burst activities of neutrophils in sheep. Fifteen sheep were randomly divided into three groups. Groups 1 and 2 received selenium nanoparticles (1 mg/kg) or sodium selenite (1 mg/kg) orally, respectively, for ten consecutive days, and the third group was considered as the control. To determine the chemotactic and respiratory burst activities of the neutrophils, the leading front assay and the NBT test were used on heparinized blood samples that were collected at different intervals (days 0, 10th, 20th, and 30th). The results obtained showed that the chemotactic activities in groups 1 and 2 increased significantly on the 10th, 20th, and 30th day, compared to day 0, and on the 20th day in comparison with the 10th day, while in group 2, there was a significant decrease on the 30th day compared to the 20th day. The chemotactic activities in group 1 were significantly higher than in group 2 on the 10th day and in the control group on the 10th, 20th, and 30th day, but the chemotactic activities in group 2 were significantly higher than those in the control group only on the 20th day. On the 30th day into the experiment, the respiratory bursts in groups 1 and 2 were significantly stronger in comparison with those at day 0. Overall, nano-selenium increased the chemotactic and respiratory burst activities more significantly than sodium selenite, which is suggestive of a stronger stimulatory effect of the Se nanoparticles on intracellular activities.

Urease-independent chemotactic responses of Helicobacter pylori to urea, urease inhibitors, and sodium bicarbonate.

PubMed Central

Mizote, T; Yoshiyama, H; Nakazawa, T

1997-01-01

Helicobacter pylori CPY3401 and an isogenic urease-negative mutant, HPT73, showed chemotactic responses to urea, flurofamide (a potent urease inhibitor), and sodium bicarbonate. Since urea and sodium bicarbonate are secreted through the gastric epithelial surface and hydrolysis of urea by urease on the bacterial surface is essential for colonization, the chemotactic response of H. pylori may be crucial for its colonization and persistence in the stomach. PMID:9119496

Acquired granulocyte abnormality during drug allergic reactions: possible role of complement activation.

PubMed

Bowers, T K; Craddock, P R; Jacob, H S

1977-01-01

A profound defect in granulocyte chemotaxis was documented in an otherwise healthy 21-yr-old man who failed to localize granulocytes to an area of cellulitis during an allergic reaction to cephalothin. During the period of drug allergy, characterized by urticaria, eosinophilia, and profound hypocomplementemia, in vitro migration of the patient's granulocytes in the Boyden chamber was markedly impaired. Although devoid of hemolytic complement activity, the patient's serum possessed supranormal chemotactic activity, even following heat inactivation, suggesting the presence of chemotactically active complement split products. Chemotactic function improved concomitantly with steroid therapy and normalization of serum complement levels, and was entirely normal following clinical recovery and cessation of steroid therapy. The chemotactic abnormality noted in the patient's cells was reproduced in normal granulocytes by preincubation either with patient serum or with cobra venom-activated fresh (but not heated) normal serum, suggesting that in vivo exposure of granulocytes to activated complement was responsible for the patient's abnormal chemotactic response. This mechanism may contribute to the increased infection propensity noted in other conditions characterized by in vivo complement activation, such as rheumatoid arthritis and systemic lupus erythematosis.

Competitive Stem Cell Recruitment by Multiple Cytotactic Cues

PubMed Central

Mendelson, Avital; Cheung, Yukkee; Paluch, Kamila; Chen, Mo; Kong, Kimi; Tan, Jiali; Dong, Ziming; Sia, Samuel K.; Mao, Jeremy J.

2014-01-01

A multitude of cytotactic cues direct cell migration in development, cancer metastasis and wound healing. However, our understanding of cell motility remains fragmented partially because current migration devices only allow the study of independent factors. We developed a cell motility assay that allows competitive recruitment of a given cell population simultaneously by gradients of multiple cytotactic cues, observable under real-time imaging. Well-defined uniform gradients of cytotactic cues can be independently generated and sustained in each channel. As a case study, bone marrow mesenchymal stem/stromal cells (MSCs) were exposed to 15 cytokines that are commonly present in arthritis. Cytokines that induced robust recruitment of MSCs in multiple groups were selected to ‘compete’ in a final round to yield the most chemotactic factor(s) based on cell migration numbers, distances, migration indices and motility over time. The potency of a given cytokine in competition frequently differed from its individual action, substantiating the need to test multiple cytokines concurrently due to synergistic or antagonistic effects. This new device has the rare capacity to screen molecules that induce cell migration in cancer therapy, drug development and tissue regeneration. PMID:23364311

EXPERIMENTAL STUDIES ON INFLAMMATION

PubMed Central

Wolf, Elizabeth Pauline

1921-01-01

1. Wright's method for the study of chemotaxis of leucocytes in vitro, slightly modified, has been found to be most satisfactory in the estimation of the degree of chemotaxis of various substances, because it is possible to make an exact quantitative determination of the leucocytes that have migrated from the blood clot and adhere to the surfaces containing the tested substance. 2. The calcium ion is the only inorganic ion per se which is found to be positively chemotactic under the conditions of these experiments. It is markedly chemotactic in all concentrations and in all combinations, except the citrate. Here the negative chemotaxis of the citrate ion neutralizes the positive chemotaxis of the calcium ion, and neutrality of chemotactic effect results. 3. The sodium and magnesium ions themselves are neutral. Magnesium and sodium salts are dependent upon the negative ion with which the magnesium or sodium is combined for such positive or negative chemotaxis as is exhibited. All the phosphates of sodium, whether tri-, di-, or monobasic salts, are markedly positively chemotactic, and when combined with other reagents which are themselves neutral or negatively chemotactic, produce marked positive chemotaxis. The blood of a person who has taken phosphates either by mouth or intravenously shows a great increase in chemotaxis with sodium phosphate, with calcium chloride, and even with sodium chloride which is ordinarily neutral. 4. All potassium salts are negatively chemotactic. 5. Many substances act synergistically as regards chemotaxis; e.g., when strontium and magnesium salts are mixed there is a marked increase in chemotaxis. Sodium phosphate acts synergistically with calcium chloride. 6. Mercury salts fix the leucocytes in this method so that their influence on chemotaxis cannot be determined. 7. Morphine and morphine salts are positively chemotactic; this is contrary to the results obtained by others with different methods. 8. Substances which produce a very acute inflammation, such as cantharidin, histamine, or turpentine, are found to be positively chemotactic by this method, but substances, such as mustard gas, which produce a marked necrotizing effect are found to be negatively chemotactic, or neutral, though physiologically they would appear to be positively chemotactic. 9. All amino-acids and amines are positively chemotactic to a certain extent. It seems that the longer the carbon chain, the greater the degree of chemotaxis, though this is not absolute. Tyramine is one exception to this, for it causes a peculiar clumping of the cells, so that it is impossible to count the number adhering, and thus determine whether or not tyramine is positively chemotactic. 10. The time that the blood of animals is examined after eating makes a marked difference in the number of cells adhering, for shortly after eating, within 30 minutes, very many more cells will adhere to the agar than at a later time. 11. The blood of different species of animals reacts differently towards different reagents. The chemical composition of these agents seems to have nothing to do with this difference in reaction as far as we could determine. 12. With frozen serial sections it has been found that the depth of penetration of the leucocytes into the agar is proportional to the positive chemotaxis produced by the substance combined with the agar, as demonstrated by the number of leucocytes adherent to the walls of the test chambers. PMID:19868564

EXPERIMENTAL STUDIES ON INFLAMMATION : I. THE INFLUENCE OF CHEMICALS UPON THE CHEMOTAXIS OF LEUCOCYTES IN VITRO.

PubMed

Wolf, E P

1921-09-30

1. Wright's method for the study of chemotaxis of leucocytes in vitro, slightly modified, has been found to be most satisfactory in the estimation of the degree of chemotaxis of various substances, because it is possible to make an exact quantitative determination of the leucocytes that have migrated from the blood clot and adhere to the surfaces containing the tested substance. 2. The calcium ion is the only inorganic ion per se which is found to be positively chemotactic under the conditions of these experiments. It is markedly chemotactic in all concentrations and in all combinations, except the citrate. Here the negative chemotaxis of the citrate ion neutralizes the positive chemotaxis of the calcium ion, and neutrality of chemotactic effect results. 3. The sodium and magnesium ions themselves are neutral. Magnesium and sodium salts are dependent upon the negative ion with which the magnesium or sodium is combined for such positive or negative chemotaxis as is exhibited. All the phosphates of sodium, whether tri-, di-, or monobasic salts, are markedly positively chemotactic, and when combined with other reagents which are themselves neutral or negatively chemotactic, produce marked positive chemotaxis. The blood of a person who has taken phosphates either by mouth or intravenously shows a great increase in chemotaxis with sodium phosphate, with calcium chloride, and even with sodium chloride which is ordinarily neutral. 4. All potassium salts are negatively chemotactic. 5. Many substances act synergistically as regards chemotaxis; e.g., when strontium and magnesium salts are mixed there is a marked increase in chemotaxis. Sodium phosphate acts synergistically with calcium chloride. 6. Mercury salts fix the leucocytes in this method so that their influence on chemotaxis cannot be determined. 7. Morphine and morphine salts are positively chemotactic; this is contrary to the results obtained by others with different methods. 8. Substances which produce a very acute inflammation, such as cantharidin, histamine, or turpentine, are found to be positively chemotactic by this method, but substances, such as mustard gas, which produce a marked necrotizing effect are found to be negatively chemotactic, or neutral, though physiologically they would appear to be positively chemotactic. 9. All amino-acids and amines are positively chemotactic to a certain extent. It seems that the longer the carbon chain, the greater the degree of chemotaxis, though this is not absolute. Tyramine is one exception to this, for it causes a peculiar clumping of the cells, so that it is impossible to count the number adhering, and thus determine whether or not tyramine is positively chemotactic. 10. The time that the blood of animals is examined after eating makes a marked difference in the number of cells adhering, for shortly after eating, within 30 minutes, very many more cells will adhere to the agar than at a later time. 11. The blood of different species of animals reacts differently towards different reagents. The chemical composition of these agents seems to have nothing to do with this difference in reaction as far as we could determine. 12. With frozen serial sections it has been found that the depth of penetration of the leucocytes into the agar is proportional to the positive chemotaxis produced by the substance combined with the agar, as demonstrated by the number of leucocytes adherent to the walls of the test chambers.

The development of concentration gradients in a suspension of chemotactic bacteria

NASA Technical Reports Server (NTRS)

Hillesdon, A. J.; Pedley, T. J.; Kessler, J. O.

1995-01-01

When a suspension of bacterial cells of the species Bacillus subtilis is placed in a chamber with its upper surface open to the atmosphere complex bioconvection patterns are observed. These arise because the cells: (1) are denser than water; and (2) usually swim upwards, so that the density of an initially uniform suspension becomes greater at the top than the bottom. When the vertical density gradient becomes large enough, an overturning instability occurs which ultimately evolves into the observed patterns. The reason that the cells swim upwards is that they are aerotactic, i.e., they swim up gradients of oxygen, and they consume oxygen. These properties are incorporated in conservation equations for the cell (N) and oxygen (C) concentrations, and these are solved in the pre-instability phase of development when N and C depend only on the vertical coordinate and time. Numerical results are obtained for both shallow- and deep-layer chambers, which are intrinsically different and require different mathematical and numerical treatments. It is found that, for both shallow and deep chambers, a thin boundary layer, densely packed with cells, forms near the surface. Beneath this layer the suspension becomes severely depleted of cells. Furthermore, in the deep chamber cases, a discontinuity in the cell concentration arises between this cell-depleted region and a cell-rich region further below, where no significant oxygen concentration gradients develop before the oxygen is fully consumed. The results obtained from the model are in good qualitative agreement with the experimental observations.

The chemotactic activity of sputum from patients with bronchiectasis.

PubMed

Mikami, M; Llewellyn-Jones, C G; Bayley, D; Hill, S L; Stockley, R A

1998-03-01

Persistent polymorphonuclear neutrophil (PMN) recruitment to airway is thought to be an important component of continuing inflammation and progression of chronic destructive lung diseases. Although chemoattractants are required for the PMN to migrate, the nature of the chemoattractants in the airways has not yet been clarified. We therefore investigated the contribution of interleukin-8 (IL-8) and leukotriene-B4 (LTB4) to the chemotactic activity of lung secretions by inhibiting their activity using a monoclonal antibody to IL-8 and an LTB4 receptor antagonist (LY293111 sodium). Fifty-nine sputum samples obtained from 19 patients with bronchiectasis were studied. In preliminary studies the chemotactic responses to IL-8 and LTB4 were found to be additive, and we were able to remove their contribution independently with the appropriate antibody and antagonist. The chemotactic activity of the secretions was related to the macroscopic appearance (mucoid, mucopurulent, and purulent), and this appeared to be related to an increase in IL-8 contribution. Chemotactic activity was reduced by antibiotic therapy and again that seemed to relate to a reduction in the IL-8 contribution. The contributions of LTB4 were similar among the three types of sputum in varying clinical states. These data suggest that LTB4 and IL-8 are important chemotactic factors in lung secretions from such patients, although IL-8 appears to play a more important role during acute exacerbations. These results may be useful in determining therapeutic strategies for chronic destructive lung diseases in the future.

Generation and partial characterization of an eosinophil chemotactic cytokine produced by sensitized equine mononuclear cells stimulated with Strongylus vulgaris antigen.

PubMed

Dennis, V A; Klei, T R; Chapman, M R

1993-07-01

Supernatants generated by stimulation of peripheral blood mononuclear cells (PBMC) from Strongylus vulgaris sensitized or immunized ponies were assayed in vitro for eosinophil chemotactic activity (ECA) using the filter system in blind well chambers. The supernatants from these cultures were chemotactic for eosinophils, but not for neutrophils. Supernates from cultures of unsensitized PBMC stimulated with S. vulgaris antigen were not chemotactic for eosinophils. ECA was first detected in culture supernatants after 1.5 h of incubation and was dependent on both antigen and PBMC concentrations, but independent of serum concentrations. Both female and male S. vulgaris worm antigens stimulated ECA production from sensitized PBMC. ECA was not induced by in vitro stimulation of sensitized S. vulgaris PBMC by female Strongylus edentatus worm antigen. Partial characterization of the eosinophil chemotactic cytokine showed it to be nondialyzable, greater than 8000 molecular weight (MW), and sensitive to heating (56 and 95 degrees C), trypsin, and sodium metaperiodate treatments, suggesting that the cytokine is a protein containing some essential carbohydrate moieties. The cytokine described in this paper could partially contribute to the in vivo blood and tissue eosinophilia in experimental S. vulgaris infection.

Conformational suppression of inter-receptor signaling defects

PubMed Central

Ames, Peter; Parkinson, John S.

2006-01-01

Motile bacteria follow gradients of attractant and repellent chemicals with high sensitivity. Their chemoreceptors are physically clustered, which may enable them to function as a cooperative array. Although native chemoreceptor molecules are typically transmembrane homodimers, they appear to associate through their cytoplasmic tips to form trimers of dimers, which may be an important architectural element in the assembly and operation of receptor clusters. The five receptors of Escherichia coli that mediate most of its chemotactic and aerotactic behaviors have identical trimer contact residues and have been shown by in vivo crosslinking methods to form mixed trimers of dimers. Mutations at the trimer contact sites of Tsr, the serine chemoreceptor, invariably abrogate Tsr function, but some of those lesions (designated Tsr*) are epistatic and block the function of heterologous chemoreceptors. We isolated and characterized mutations (designated Tar⋀) in the aspartate chemoreceptor that restored function to Tsr* receptors. The suppressors arose at or near the Tar trimer contact sites and acted in an allele-specific fashion on Tsr* partners. Alone, many Tar⋀ receptors were unable to mediate chemotactic responses to aspartate, but all formed clusters with varying efficiencies. Most of those Tar⋀ receptors were epistatic to WT Tsr, but some regained Tar function in combination with a suppressible Tsr* partner. Tar⋀–Tsr* suppression most likely occurs through compensatory changes in the conformation or dynamics of a mixed receptor signaling complex, presumably based on trimer-of-dimer interactions. These collaborative teams may be responsible for the high-gain signaling properties of bacterial chemoreceptors. PMID:16751275

A Worldwide Competition to Compare the Speed and Chemotactic Accuracy of Neutrophil-Like Cells

PubMed Central

Wong, Elisabeth; Hamza, Bashar; Bae, Albert; Martel, Joseph; Kataria, Rama; Keizer-Gunnink, Ineke; Kortholt, Arjan; Van Haastert, Peter J. M.; Charras, Guillaume; Janetopoulos, Christopher; Irimia, Daniel

2016-01-01

Chemotaxis is the ability to migrate towards the source of chemical gradients. It underlies the ability of neutrophils and other immune cells to hone in on their targets and defend against invading pathogens. Given the importance of neutrophil migration to health and disease, it is crucial to understand the basic mechanisms controlling chemotaxis so that strategies can be developed to modulate cell migration in clinical settings. Because of the complexity of human genetics, Dictyostelium and HL60 cells have long served as models system for studying chemotaxis. Since many of our current insights into chemotaxis have been gained from these two model systems, we decided to compare them side by side in a set of winner-take-all races, the Dicty World Races. These worldwide competitions challenge researchers to genetically engineer and pharmacologically enhance the model systems to compete in microfluidic racecourses. These races bring together technological innovations in genetic engineering and precision measurement of cell motility. Fourteen teams participated in the inaugural Dicty World Race 2014 and contributed cell lines, which they tuned for enhanced speed and chemotactic accuracy. The race enabled large-scale analyses of chemotaxis in complex environments and revealed an intriguing balance of speed and accuracy of the model cell lines. The successes of the first race validated the concept of using fun-spirited competition to gain insights into the complex mechanisms controlling chemotaxis, while the challenges of the first race will guide further technological development and planning of future events. PMID:27332963

Distribution of self-propelled organisms in fluid flows

NASA Astrophysics Data System (ADS)

Neufeld, Zoltan

2006-11-01

We study the distribution of microorganisms represented as self-propelled particles in a moving fluid medium. The particles are advected by the flow and, in addition, they swim in a direction controlled by external factors. Two cases are considered: 1. passive spheroidal particles, that swim with constant speed but the swimming direction is reoriented by the viscous torque acting on the spheroid due to the local velocity field, and 2. chemotactic particles, whose swimming speed is oriented and proportional to the gradient of the concentration of a chemoattractant. We show that the combined effects of chaotic mixing and chemotaxis or flow reorientation leads to aggregation of the particles along a complex manifold. We analyse the properties of the aggregates and the efficiency of chemotaxis in flows with strongly non-uniform fluctuating distribution of the chemottractant.

Optimal chemotaxis in intermittent migration of animal cells

NASA Astrophysics Data System (ADS)

Romanczuk, P.; Salbreux, G.

2015-04-01

Animal cells can sense chemical gradients without moving and are faced with the challenge of migrating towards a target despite noisy information on the target position. Here we discuss optimal search strategies for a chaser that moves by switching between two phases of motion ("run" and "tumble"), reorienting itself towards the target during tumble phases, and performing persistent migration during run phases. We show that the chaser average run time can be adjusted to minimize the target catching time or the spatial dispersion of the chasers. We obtain analytical results for the catching time and for the spatial dispersion in the limits of small and large ratios of run time to tumble time and scaling laws for the optimal run times. Our findings have implications for optimal chemotactic strategies in animal cell migration.

Antimicrobial peptide scolopendrasin VII, derived from the centipede Scolopendra subspinipes mutilans, stimulates macrophage chemotaxis via formyl peptide receptor 1

PubMed Central

Park, Yoo Jung; Lee, Ha Young; Jung, Young Su; Park, Joon Seong; Hwang, Jae Sam; Bae, Yoe-Sik

2015-01-01

In this study, we report that one of the antimicrobial peptides scolopendrasin VII, derived from Scolopendra subspinipes mutilans, stimulates actin polymerization and the subsequent chemotactic migration of macrophages through the activation of ERK and protein kinase B (Akt) activity. The scolopendrasin VII-induced chemotactic migration of macrophages is inhibited by the formyl peptide receptor 1 (FPR1) antagonist cyclosporine H. We also found that scolopendrasin VII stimulate the chemotactic migration of FPR1-transfected RBL-2H3 cells, but not that of vector-transfected cells; moreover, scolopendrasin VII directly binds to FPR1. Our findings therefore suggest that the antimicrobial peptide scolopendrasin VII, derived from Scolopendra subspinipes mutilans, stimulates macrophages, resulting in chemotactic migration via FPR1 signaling, and the peptide can be useful in the study of FPR1-related biological responses. [BMB Reports 2015; 48(8): 479-484] PMID:26129676

Precision sensing by two opposing gradient sensors: how does Escherichia coli find its preferred pH level?

PubMed

Hu, Bo; Tu, Yuhai

2013-07-02

It is essential for bacteria to find optimal conditions for their growth and survival. The optimal levels of certain environmental factors (such as pH and temperature) often correspond to some intermediate points of the respective gradients. This requires the ability of bacteria to navigate from both directions toward the optimum location and is distinct from the conventional unidirectional chemotactic strategy. Remarkably, Escherichia coli cells can perform such a precision sensing task in pH taxis by using the same chemotaxis machinery, but with opposite pH responses from two different chemoreceptors (Tar and Tsr). To understand bacterial pH sensing, we developed an Ising-type model for a mixed cluster of opposing receptors based on the push-pull mechanism. Our model can quantitatively explain experimental observations in pH taxis for various mutants and wild-type cells. We show how the preferred pH level depends on the relative abundance of the competing sensors and how the sensory activity regulates the behavioral response. Our model allows us to make quantitative predictions on signal integration of pH and chemoattractant stimuli. Our study reveals two general conditions and a robust push-pull scheme for precision sensing, which should be applicable in other adaptive sensory systems with opposing gradient sensors. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Acute Chorioamnionitis and Funisitis: Definition, Pathologic Features, and Clinical Significance

PubMed Central

Kim, Chong Jai; Romero, Roberto; Chaemsaithong, Piya; Chaiyasit, Noppadol; Yoon, Bo Hyun; Kim, Yeon Mee

2015-01-01

Acute inflammatory lesions of the placenta consist of diffuse infiltration of neutrophils at different sites in the organ. These lesions include acute chorioamnionitis, funisitis, and chorionic vasculitis, and represent a host response (maternal or fetal) to a chemotactic gradient in the amniotic cavity. While acute chorioamnionitis is evidence of a maternal host response, funisitis and chorionic vasculitis represent fetal inflammatory responses. Intra-amniotic infection has been generally considered to be the cause of acute histologic chorioamnionitis and funisitis; however, recent evidence indicates that “sterile” intra-amniotic inflammation, which occurs in the absence of demonstrable microorganisms but can be induced by “danger signals”, is frequently associated with these lesions. In the context of intra-amniotic infection, chemokines (such as interleukin-8 and granulocyte chemotactic protein) establish a gradient favoring the migration of neutrophils from maternal or fetal circulation into the chorioamniotic membranes or umbilical cord, respectively. Danger signals released during the course of cellular stress or cell death can also induce the release of neutrophil chemokines. The prevalence of chorioamnionitis is a function of gestational age at birth, and is present in 3-5% of placentas delivered at term, but in 94% of placentas delivered between 21-24 weeks of gestation. The frequency is higher in patients with spontaneous labor, preterm labor, clinical chorioamnionitis (preterm or term), or ruptured membranes. Funisitis and chorionic vasculitis are the hallmarks for the fetal inflammatory response syndrome, a condition characterized by an elevation in fetal plasma concentrations of interleukin-6, associated with the impending onset of preterm labor, a higher rate of neonatal morbidity (after adjustment for gestational age), and multi-organ fetal involvement. This syndrome is the counterpart of the systemic inflammatory response syndrome in adults; however, in fetuses, it is a risk factor for short- and long-term complications (i.e. neonatal sepsis, bronchopulmonary dysplasia, periventricular leukomalacia, and cerebral palsy). This article reviews the definition, pathogenesis, grading and staging, and clinical significance of the most common lesions in placental pathology. Illustrations of the lesions and diagrams of the mechanisms of disease are provided. PMID:26428501

Migration of Chemotactic Bacteria in Soft Agar: Role of Gel Concentration

PubMed Central

Croze, Ottavio A.; Ferguson, Gail P.; Cates, Michael E.; Poon, Wilson C.K.

2011-01-01

We study the migration of chemotactic wild-type Escherichia coli populations in semisolid (soft) agar in the concentration range C = 0.15–0.5% (w/v). For C≲0.35%, expanding bacterial colonies display characteristic chemotactic rings. At C = 0.35%, however, bacteria migrate as broad circular bands rather than sharp rings. These are growth/diffusion waves arising because of suppression of chemotaxis by the agar and have not been previously reported experimentally to our knowledge. For C = 0.4–0.5%, expanding colonies do not span the depth of the agar and develop pronounced front instabilities. The migration front speed is weakly dependent on agar concentration at C < 0.25%, but decreases sharply above this value. We discuss these observations in terms of an extended Keller-Segel model for which we derived novel transport parameter expressions accounting for perturbations of the chemotactic response by collisions with the agar. The model makes it possible to fit the observed front speed decay in the range C = 0.15–0.35%, and its solutions qualitatively reproduce the observed transition from chemotactic to growth/diffusion bands. We discuss the implications of our results for the study of bacteria in porous media and for the design of improved bacteriological chemotaxis assays. PMID:21806920

High throughput MLVA-16 typing for Brucella based on the microfluidics technology

PubMed Central

2011-01-01

Background Brucellosis, a zoonosis caused by the genus Brucella, has been eradicated in Northern Europe, Australia, the USA and Canada, but remains endemic in most areas of the world. The strain and biovar typing of Brucella field samples isolated in outbreaks is useful for tracing back source of infection and may be crucial for discriminating naturally occurring outbreaks versus bioterrorist events, being Brucella a potential biological warfare agent. In the last years MLVA-16 has been described for Brucella spp. genotyping. The MLVA band profiles may be resolved by different techniques i.e. the manual agarose gels, the capillary electrophoresis sequencing systems or the microfluidic Lab-on-Chip electrophoresis. In this paper we described a high throughput system of MLVA-16 typing for Brucella spp. by using of the microfluidics technology. Results The Caliper LabChip 90 equipment was evaluated for MLVA-16 typing of sixty-three Brucella samples. Furthermore, in order to validate the system, DNA samples previously resolved by sequencing system and Agilent technology, were de novo genotyped. The comparison of the MLVA typing data obtained by the Caliper equipment and those previously obtained by the other analysis methods showed a good correlation. However the outputs were not accurate as the Caliper DNA fragment sizes showed discrepancies compared with real data and a conversion table from observed to expected data was created. Conclusion In this paper we described the MLVA-16 using a rapid, sophisticated microfluidics technology for detection of amplification product sizes. The comparison of the MLVA typing data produced by Caliper LabChip 90 system with the data obtained by different techniques showed a general concordance of the results. Furthermore this platform represents a significant improvement in terms of handling, data acquiring, computational efficiency and rapidity, allowing to perform the strain genotyping in a time equal to one sixth respect to other microfluidics systems as e.g. the Agilent 2100 bioanalyzer. Finally, this platform can be considered a valid alternative to standard genotyping techniques, particularly useful dealing with a large number of samples in short time. These data confirmed that this technology represents a significative advancement in high-throughput accurate Brucella genotyping. PMID:21435217

Directed transport of bacteria-based drug delivery vehicles: bacterial chemotaxis dominates particle shape.

PubMed

Sahari, Ali; Traore, Mahama A; Scharf, Birgit E; Behkam, Bahareh

2014-10-01

Several attenuated and non-pathogenic bacterial species have been demonstrated to actively target diseased sites and successfully deliver plasmid DNA, proteins and other therapeutic agents into mammalian cells. These disease-targeting bacteria can be employed for targeted delivery of therapeutic and imaging cargos in the form of a bio-hybrid system. The bio-hybrid drug delivery system constructed here is comprised of motile Escherichia coli MG1655 bacteria and elliptical disk-shaped polymeric microparticles. The transport direction for these vehicles can be controlled through biased random walk of the attached bacteria in presence of chemoattractant gradients in a process known as chemotaxis. In this work, we utilize a diffusion-based microfluidic platform to establish steady linear concentration gradients of a chemoattractant and investigate the roles of chemotaxis and geometry in transport of bio-hybrid drug delivery vehicles. Our experimental results demonstrate for the first time that bacterial chemotactic response dominates the effect of body shape in extravascular transport; thus, the non-spherical system could be more favorable for drug delivery applications owing to the known benefits of using non-spherical particles for vascular transport (e.g. relatively long circulation time).

The effects of nutrient chemotaxis on bacterial aggregation patterns with non-linear degenerate cross diffusion

NASA Astrophysics Data System (ADS)

Leyva, J. Francisco; Málaga, Carlos; Plaza, Ramón G.

2013-11-01

This paper studies a reaction-diffusion-chemotaxis model for bacterial aggregation patterns on the surface of thin agar plates. It is based on the non-linear degenerate cross diffusion model proposed by Kawasaki et al. (1997) [5] and it includes a suitable nutrient chemotactic term compatible with such type of diffusion, as suggested by Ben-Jacob et al. (2000) [20]. An asymptotic estimation predicts the growth velocity of the colony envelope as a function of both the nutrient concentration and the chemotactic sensitivity. It is shown that the growth velocity is an increasing function of the chemotactic sensitivity. High resolution numerical simulations using Graphic Processing Units (GPUs), which include noise in the diffusion coefficient for the bacteria, are presented. The numerical results verify that the chemotactic term enhances the velocity of propagation of the colony envelope. In addition, the chemotaxis seems to stabilize the formation of branches in the soft-agar, low-nutrient regime.

IN VITRO AND IN VIVO ACTIVITY OF A LYMPHOCYTE AND IMMUNE COMPLEX-DEPENDENT CHEMOTACTIC FACTOR FOR EOSINOPHILS

PubMed Central

Cohen, Stanley; Ward, Peter A.

1971-01-01

When cultured in the presence of specific antigen, lymphocytes from delayed-hypersensitive guinea pigs release a number of biologically active substances into the culture medium. Such active supernatants can react with immune complexes in vitro to generate a factor which is chemotactic for eosinophils. The factor involved is unique, since previously described chemotactic factors for other cell types require for their generation either immune complexes or substances released into lymphocyte culture, but not both. In the case of the eosinophil chemotactic factor, the interaction between the substance elaborated by the lymphocytes and the immune complexes appears to be specific in that the immune complexes must contain the same antigen as that used to activate the lymphocyte cultures. Although this factor was generated in an in vitro system, it has been shown to possess in vivo as well as in vitro activity. It is therefore possible that this factor may be of biological significance in situations where eosinophils are participants in inflammatory or immunologic reactions. PMID:5099667

Moesin and myosin phosphatase confine neutrophil orientation in a chemotactic gradient

PubMed Central

Liu, Xiaowen; Yang, Tao; Suzuki, Koya; Tsukita, Sachiko; Ishii, Masaru; Zhou, Shuping; Wang, Gang; Cao, Luyang; Qian, Feng; Taylor, Shalina; Oh, Myung-Jin; Levitan, Irena; Ye, Richard D.; Carnegie, Graeme K.; Malik, Asrar B.

2015-01-01

Neutrophils respond to invading bacteria by adopting a polarized morphology, migrating in the correct direction, and engulfing the bacteria. How neutrophils establish and precisely orient this polarity toward pathogens remains unclear. Here we report that in resting neutrophils, the ERM (ezrin, radixin, and moesin) protein moesin in its active form (phosphorylated and membrane bound) prevented cell polarization by inhibiting the small GTPases Rac, Rho, and Cdc42. Attractant-induced activation of myosin phosphatase deactivated moesin at the prospective leading edge to break symmetry and establish polarity. Subsequent translocation of moesin to the trailing edge confined the formation of a prominent pseudopod directed toward pathogens and prevented secondary pseudopod formation in other directions. Therefore, both moesin-mediated inhibition and its localized deactivation by myosin phosphatase are essential for neutrophil polarization and effective neutrophil tracking of pathogens. PMID:25601651

Strength and stability of microbial plugs in porous media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarkar, A.K.; Sharma, M.M.; Georgiou, G.

1995-12-31

Mobility reduction induced by the growth and metabolism of bacteria in high-permeability layers of heterogeneous reservoirs is an economically attractive technique to improve sweep efficiency. This paper describes an experimental study conducted in sandpacks using an injected bacterium to investigate the strength and stability of microbial plugs in porous media. Successful convective transport of bacteria is important for achieving sufficient initial bacteria distribution. The chemotactic and diffusive fluxes are probably not significant even under static conditions. Mobility reduction depends upon the initial cell concentrations and increase in cell mass. For single or multiple static or dynamic growth techniques, permeability reductionmore » was approximately 70% of the original permeability. The stability of these microbial plugs to increases in pressure gradient and changes in cell physiology in a nutrient-depleted environment needs to be improved.« less

Colloidal silver nanoparticles/rhamnolipid (SNPRL) composite as novel chemotactic antibacterial agent.

PubMed

Bharali, P; Saikia, J P; Paul, S; Konwar, B K

2013-10-01

The antibacterial activity of silver nanoparticles and rhamnolipid are well known individually. In the present research, antibacterial and chemotactic activity due to colloidal silver nanoparticles (SNP), rhamnolipid (RL) and silver nanoparticles/rhamnolipid composite (SNPRL) were evaluated using Staphylococcus aureus (MTCC3160), Escherichia coli (MTCC40), Pseudomonas aeruginosa (MTCC8163) and Bacillus subtilis (MTCC441) as test strains. Further, the SNPRL nanoparticles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The observation clearly indicates that SNPRL shows prominent antibacterial and chemotactic activity in comparison to all of its individual precursor components. Copyright © 2013 Elsevier B.V. All rights reserved.

Transverse Chemotactic Migration of Bacteria from High to Low Permeability Regions in a Dual Permeability Porous Microfluidic Device

NASA Astrophysics Data System (ADS)

Singh, R.; Olson, M. S.

2011-12-01

Low permeability regions sandwiched between high permeability regions such as clay lenses are difficult to treat using conventional treatment methods. Trace concentrations of contaminants such as non-aqueous phase liquids (NAPLs) remain trapped in these regions and over the time diffuse out into surrounding water thereby acting as a long term source of groundwater contamination. Bacterial chemotaxis (directed migration toward a contaminant source), may be helpful in enhancing bioremediation of such contaminated sites. This study is focused on simulating a two-dimensional dual-permeability groundwater contamination scenario using microfluidic devices and evaluating transverse chemotactic migration of bacteria from high to low permeability regions. A novel bi-layer polydimethylsiloxane (PDMS) microfluidic device was fabricated using photolithography and soft lithography techniques to simulate contamination of a dual- permeability region due to leakage from an underground storage tank into a low permeability region. This device consists of a porous channel through which a bacterial suspension (Escherchia Coli HCB33) is flown and another channel for injecting contaminant/chemo-attractant (DL-aspertic acid) into the porous channel. The pore arrangement in the porous channel contains a 2-D low permeability region surrounded by high permeability regions on both sides. Experiments were performed under chemotactic and non-chemotactic (replacing attractant with buffer solution in the non porous channel) conditions. Images were captured in transverse pore throats at cross-sections 4.9, 9.8, and 19.6 mm downstream from the attractant injection point and bacteria were enumerated in the middle of each pore throat. Bacterial chemotaxis was quantified in terms of the change in relative bacterial counts in each pore throat at cross-sections 9.8 and 19.6 mm with respect to counts at the cross-section at 4.9 mm. Under non-chemotactic conditions, relative bacterial count was observed to decrease at 9.8 mm and 19.6 mm cross-sections in low permeability regions due to dilution with the injectate from the non-porous channel (Figure 1). However, relative bacterial counts increased in the low permeability region at both downstream cross-sections under chemotactic conditions. A large increase in relative bacterial count in the pore throats just outside the low permeability region was also observed at both cross-sections (Figure 1). The bacterial chemotactic response was observed to decrease linearly with increasing Darcy velocity and at flow rate 0.220 mm/s the chemotactic effect was offset by the advective flow in the porous channel.

A model of excitation and adaptation in bacterial chemotaxis.

PubMed Central

Hauri, D C; Ross, J

1995-01-01

We present a model of the chemotactic mechanism of Escherichia coli that exhibits both initial excitation and eventual complete adaptation to any and all levels of stimulus ("exact" adaptation). In setting up the reaction network, we use only known interactions and experimentally determined cytosolic concentrations. Whenever possible, rate coefficients are first assigned experimentally measured values; second, we permit some variation in these rate coefficients by using a multiple-well optimization technique and incremental adjustment to obtain values that are sufficient to engender initial response to stimuli (excitation) and an eventual return of behavior to baseline (adaptation). The predictions of the model are similar to the observed behavior of wild-type bacteria in regard to the time scale of excitation in the presence of both attractant and repellent. The model predicts a weaker response to attractant than that observed experimentally, and the time scale of adaptation does not depend as strongly upon stimulant concentration as does that for wild-type bacteria. The mechanism responsible for long-term adaptation is local rather than global: on addition of a repellent or attractant, the receptor types not sensitive to that attractant or repellent do not change their average methylation level in the long term, although transient changes do occur. By carrying out a phenomenological simulation of bacterial chemotaxis, we find that the model is insufficiently sensitive to effect taxis in a gradient of attractant. However, by arbitrarily increasing the sensitivity of the motor to the tumble effector (phosphorylated CheY), we can obtain chemotactic behavior. Images FIGURE 6 FIGURE 7 PMID:7696522

Monocyte chemotactic protein-1 deficiency reduces spontaneous metastasis of Lewis lung carcinoma in mice fed a high-fat diet

USDA-ARS?s Scientific Manuscript database

Obesity is a risk factor for cancer. Adipose tissue produces pro-inflammatory adipokines that contribute obesity-related malignant progression. This study investigated the effects of monocyte chemotactic protein-1 (MCP-1) deficiency on pulmonary metastasis of Lewis lung carcinoma (LLC) in male C57...

Defective granulocyte chemotaxis in the Chediak-Higashi syndrome

PubMed Central

Clark, Robert A.; Kimball, Harry R.

1971-01-01

In vivo and in vitro studies of granulocyte chemotaxis were performed in three patients with the Chediak-Higashi syndrome. Rebuck skin windows showed a decreased accumulation of leukocytes at an inflammatory site. Studies in Boyden chambers documented a cellular defect in granulocyte chemotaxis. The chemotactic response of Chediak-Higashi cells by this technique averaged approximately 40% of normal and was consistently reduced using several different chemotactic stimuli. This deficit was magnified by shortening the chamber incubation time or by decreasing the pore size of the micropore filter and was independent of granulocytopenia. No abnormalities of passive motility, adhesiveness, viability, or pH optimum for migration were found in these cells. Chediak-Higashi serum contained no inhibitors of chemotaxis and was capable of generating normal amounts of chemotactic factors with the exception of one patient with the accelerated phase of the disease. Heterozygotes for the Chediak-Higashi trait had normal chemotactic function. This cellular defect in chemotaxis may contribute to the marked susceptibility to pyogenic infections which is so characteristic of patients with the Chediak-Higashi syndrome. Images PMID:4942966

Polarised Clathrin-Mediated Endocytosis of EGFR During Chemotactic Invasion

PubMed Central

Mutch, Laura Jane; Howden, Jake Davey; Jenner, Emma Poppy Louise; Poulter, Natalie Sarah; Rappoport, Joshua Zachary

2014-01-01

Directed cell migration is critical for numerous physiological processes including development and wound healing. However chemotaxis is also exploited during cancer progression. Recent reports have suggested links between vesicle trafficking pathways and directed cell migration. Very little is known about the potential roles of endocytosis pathways during metastasis. Therefore we performed a series of studies employing a previously characterised model for chemotactic invasion of cancer cells to assess specific hypotheses potentially linking endocytosis to directed cell migration. Our results demonstrate that clathrin-mediated endocytosis is indispensable for epidermal growth factor (EGF) directed chemotactic invasion of MDA-MB-231 cells. Conversely, caveolar endocytosis is not required in this mode of migration. We further found that chemoattractant receptor (EGFR) trafficking occurs by clathrin-mediated endocytosis and is polarised towards the front of migrating cells. However, we found no role for clathrin-mediated endocytosis in focal adhesion disassembly in this migration model. Thus, this study has characterised the role of endocytosis during chemotactic invasion and has identified functions mechanistically linking clathrin-mediated endocytosis to directed cell motility. PMID:24921075

The Properties of 3 Different Plasma Formulations and Their Effects on Tendinopathic Cells.

PubMed

Rubio-Azpeitia, Eva; Bilbao, Ane M; Sánchez, Pello; Delgado, Diego; Andia, Isabel

2016-08-01

Tendinopathies are attributed to failure of the healing process and inadequate tissue remodeling. Plasma injections can trigger regenerative responses by modifying the molecular microenvironment. To examine the differences in the mitotic, chemotactic, anabolic, and inflammatory effects between leukocyte- and platelet-rich plasma (L-PRP), platelet-rich plasma (PRP), and platelet-poor plasma (PPP). Controlled laboratory study. Tendinopathic cells were cultured in 3-dimensional (3D) hydrogels formed using PPP, PRP, and L-PRP. Cell migration was evaluated using a μ-Slide chemotaxis chamber with video microscopy. Proliferation was assessed using XTT assays. Expression of genes associated with matrix turnover, including type 1 collagen (COL1A1), COL3A1, aggrecan, decorin, fibronectin, matrix metalloproteinase 1 (MMP-1), MMP-3, A Disintegrin-Like And Metalloprotease With Thrombospondin Type 1 Motif proteins 4 (ADAMTS-4), and ADAMTS-5, was assessed using real-time reverse-transcription polymerase chain reaction. Secreted inflammatory proteins, including interleukin (IL)-1β, IL-6, IL-8, monocyte chemotactic protein 1 (MCP-1), and regulated on activation, normal T cell expressed and secreted (RANTES), as well as vascular endothelial growth factor (VEGF) and connective tissue growth factor (CTGF), were quantified using enzyme-linked immunosorbent assay. Tendinopathic cells migrate at a higher velocity along L-PRP and PRP than along PPP gradients. PRP and L-PRP promote hypercellularity. PPP and PRP showed more pronounced anabolic properties, as demonstrated by enhanced COL1A1 and COL3A1 and reduced MMP-1 expression. Decorin, fibronectin, and aggrecan were downregulated in L-PRP compared with PPP and PRP. L-PRP and PRP were shown to be more proinflammatory than PPP in terms of IL-6 secretion, but cells in PPP showed MCP-1(high) phenotype. CTGF secretion was significantly reduced in L-PRP compared with PPP and PRP. The main advantages of L-PRP and PRP use, compared with PPP, include their stronger chemotactic and proliferative properties. While PPP and PRP stimulate matrix anabolism, L-PRP is more proinflammatory. Emphasis should be placed on the temporal needs and biological characteristics of injured tendons, and plasma formulations need to be tailored accordingly. Versatile systems allowing the preparation of different plasma formulations, such as PPP, PRP, or L-PRP, can help refine clinical applications by taking advantage of their different biological properties. © 2016 The Author(s).

Quantification of transendothelial migration using three-dimensional confocal microscopy.

PubMed

Cain, Robert J; d'Água, Bárbara Borda; Ridley, Anne J

2011-01-01

Migration of cells across endothelial barriers, termed transendothelial migration (TEM), is an important cellular process that underpins the pathology of many disease states including chronic inflammation and cancer metastasis. While this process can be modeled in vitro using cultured cells, many model systems are unable to provide detailed visual information of cell morphologies and distribution of proteins such as junctional markers, as well as quantitative data on the rate of TEM. Improvements in imaging techniques have made microscopy-based assays an invaluable tool for studying this type of detailed cell movement in physiological processes. In this chapter, we describe a confocal microscopy-based method that can be used to assess TEM of both leukocytes and cancer cells across endothelial barriers in response to a chemotactic gradient, as well as providing information on their migration into a subendothelial extracellular matrix, designed to mimic that found in vivo.

Collective Surfing of Chemically Active Particles

NASA Astrophysics Data System (ADS)

Masoud, Hassan; Shelley, Michael J.

2014-03-01

We study theoretically the collective dynamics of immotile particles bound to a 2D surface atop a 3D fluid layer. These particles are chemically active and produce a chemical concentration field that creates surface-tension gradients along the surface. The resultant Marangoni stresses create flows that carry the particles, possibly concentrating them. For a 3D diffusion-dominated concentration field and Stokesian fluid we show that the surface dynamics of active particle density can be determined using nonlocal 2D surface operators. Remarkably, we also show that for both deep or shallow fluid layers this surface dynamics reduces to the 2D Keller-Segel model for the collective chemotactic aggregation of slime mold colonies. Mathematical analysis has established that the Keller-Segel model can yield finite-time, finite-mass concentration singularities. We show that such singular behavior occurs in our finite-depth system, and study the associated 3D flow structures.

Dual GPCR and GAG mimicry by the M3 chemokine decoy receptor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexander-Brett, Jennifer M.; Fremont, Daved H.

2008-09-23

Viruses have evolved a myriad of evasion strategies focused on undermining chemokine-mediated immune surveillance, exemplified by the mouse {gamma}-herpesvirus 68 M3 decoy receptor. Crystal structures of M3 in complex with C chemokine ligand 1/lymphotactin and CC chemokine ligand 2/monocyte chemoattractant protein 1 reveal that invariant chemokine features associated with G protein-coupled receptor binding are primarily recognized by the decoy C-terminal domain, whereas the N-terminal domain (NTD) reconfigures to engage divergent basic residue clusters on the surface of chemokines. Favorable electrostatic forces dramatically enhance the association kinetics of chemokine binding by M3, with a primary role ascribed to acidic NTD regionsmore » that effectively mimic glycosaminoglycan interactions. Thus, M3 employs two distinct mechanisms of chemical imitation to potently sequester chemokines, thereby inhibiting chemokine receptor binding events as well as the formation of chemotactic gradients necessary for directed leukocyte trafficking.« less

Development of a Single-Cell Migration and Extravasation Platform through Selective Surface Modification.

PubMed

Roberts, Steven A; Waziri, Allen E; Agrawal, Nitin

2016-03-01

Cell migration through three-dimensional (3D) tissue spaces is integral to many biological and pathological processes, including metastasis. Circulating tumor cells (CTCs) are phenotypically heterogeneous, and in vitro analysis of their extravasation behavior is often impeded by the inability to establish complex tissue-like extracellular matrix (ECM) environments and chemotactic gradients within microfluidic devices. We have developed a novel microfluidic strategy to manipulate surface properties of enclosed microchannels and create 3D ECM structures for real-time observation of individual migrating cells. The wettability of selective interconnected channels is controlled by a plasma pulse, enabling the incorporation of ECM exclusively within the transmigration regions. We applied this approach to collectively analyze CTC-endothelial adhesion, trans-endothelial migration, and subsequent motility of breast cancer cells (MDA-MB-231) through a 3D ECM under artificial gradients of SDF-1α. We observed migration velocities ranging from 5.12 to 12.8 μm/h, which closely correspond to single-cell migration in collagen blocks, but are significantly faster than the migration of cell aggregates. The compartmentalized microchannels separated by the porous ECM makes this in vitro assay versatile and suitable for a variety of applications such as inflammation studies, drug screening, and coculture interactions.

Active Brownian motion tunable by light.

PubMed

Buttinoni, Ivo; Volpe, Giovanni; Kümmel, Felix; Volpe, Giorgio; Bechinger, Clemens

2012-07-18

Active Brownian particles are capable of taking up energy from their environment and converting it into directed motion; examples range from chemotactic cells and bacteria to artificial micro-swimmers. We have recently demonstrated that Janus particles, i.e. gold-capped colloidal spheres, suspended in a critical binary liquid mixture perform active Brownian motion when illuminated by light. In this paper, we investigate in more detail their swimming mechanism, leading to active Brownian motion. We show that the illumination-borne heating induces a local asymmetric demixing of the binary mixture, generating a spatial chemical concentration gradient which is responsible for the particle's self-diffusiophoretic motion. We study this effect as a function of the functionalization of the gold cap, the particle size and the illumination intensity: the functionalization determines what component of the binary mixture is preferentially adsorbed at the cap and the swimming direction (towards or away from the cap); the particle size determines the rotational diffusion and, therefore, the random reorientation of the particle; and the intensity tunes the strength of the heating and, therefore, of the motion. Finally, we harness this dependence of the swimming strength on the illumination intensity to investigate the behavior of a micro-swimmer in a spatial light gradient, where its swimming properties are space-dependent.

Low Piconewton Towing of CNS Axons against Diffusing and Surface-Bound Repellents Requires the Inhibition of Motor Protein-Associated Pathways

NASA Astrophysics Data System (ADS)

Kilinc, Devrim; Blasiak, Agata; O'Mahony, James J.; Lee, Gil U.

2014-11-01

Growth cones, dynamic structures at axon tips, integrate chemical and physical stimuli and translate them into coordinated axon behaviour, e.g., elongation or turning. External force application to growth cones directs and enhances axon elongation in vitro; however, direct mechanical stimulation is rarely combined with chemotactic stimulation. We describe a microfluidic device that exposes isolated cortical axons to gradients of diffusing and substrate-bound molecules, and permits the simultaneous application of piconewton (pN) forces to multiple individual growth cones via magnetic tweezers. Axons treated with Y-27632, a RhoA kinase inhibitor, were successfully towed against Semaphorin 3A gradients, which repel untreated axons, with less than 12 pN acting on a small number of neural cell adhesion molecules. Treatment with Y-27632 or monastrol, a kinesin-5 inhibitor, promoted axon towing on substrates coated with chondroitin sulfate proteoglycans, potent axon repellents. Thus, modulating key molecular pathways that regulate contractile stress generation in axons counteracts the effects of repellent molecules and promotes tension-induced growth. The demonstration of parallel towing of axons towards inhibitory environments with minute forces suggests that mechanochemical stimulation may be a promising therapeutic approach for the repair of the damaged central nervous system, where regenerating axons face repellent factors over-expressed in the glial scar.

A novel optical assay system for the quantitative measurement of chemotaxis.

PubMed

Kanegasaki, Shiro; Nomura, Yuka; Nitta, Nao; Akiyama, Shuichi; Tamatani, Takuya; Goshoh, Yasuhiro; Yoshida, Takashi; Sato, Tsuyoshi; Kikuchi, Yuji

2003-11-01

We have developed an optically accessible, horizontal chemotaxis apparatus consisting of an etched silicon substrate and a flat glass plate, both of which form two compartments with a 5-microm-deep microchannel in between. The device is held together with a stainless steel holder with holes for injecting cells and a chemoattractant to the different compartments. Migration of cells in the channel is traced with time-lapse intervals using a CCD camera. By developing a method for aligning cells at the edge of the channel, we could successfully reduce the number of cells required for a chemotactic assay, depending on the experiment, to 100 or less. To prevent ceaseless flow of contents between the adjacent compartments via the communicating microchannel, a space at the top end of the holder was filled with medium after aligning the cells. By using a fluorescent probe, we demonstrated experimentally that a stable concentration gradient could be maintained. Furthermore, we determined theoretical details of the gradient established using a model chemokine and a computational fluid dynamics code. Reproducible kinetic results of cell migration were obtained using human neutrophils and IL-8 as a model. Migration of other cells such as eosinophils, basophils and Jurkat lymphocytes toward the appropriate chemokines were also demonstrated.

Blood vessel endothelium-directed tumor cell streaming in breast tumors requires the HGF/C-Met signaling pathway

PubMed Central

Leung, E; Xue, A; Wang, Y; Rougerie, P; Sharma, V P; Eddy, R; Cox, D; Condeelis, J

2017-01-01

During metastasis to distant sites, tumor cells migrate to blood vessels. In vivo, breast tumor cells utilize a specialized mode of migration known as streaming, where a linear assembly of tumor cells migrate directionally towards blood vessels on fibronectin-collagen I-containing extracellular matrix (ECM) fibers in response to chemotactic signals. We have successfully reconstructed tumor cell streaming in vitro by co-plating tumors cells, macrophages and endothelial cells on 2.5 μm thick ECM-coated micro-patterned substrates. We found that tumor cells and macrophages, when plated together on the micro-patterned substrates, do not demonstrate sustained directional migration in only one direction (sustained directionality) but show random bi-directional walking. Sustained directionality of tumor cells as seen in vivo was established in vitro when beads coated with human umbilical vein endothelial cells were placed at one end of the micro-patterned ‘ECM fibers' within the assay. We demonstrated that these endothelial cells supply the hepatocyte growth factor (HGF) required for the chemotactic gradient responsible for sustained directionality. Using this in vitro reconstituted streaming system, we found that directional streaming is dependent on, and most effectively blocked, by inhibiting the HGF/C-Met signaling pathway between endothelial cells and tumor cells. Key observations made with the in vitro reconstituted system implicating C-Met signaling were confirmed in vivo in mammary tumors using the in vivo invasion assay and intravital multiphoton imaging of tumor cell streaming. These results establish HGF/C-Met as a central organizing signal in blood vessel-directed tumor cell migration in vivo and highlight a promising role for C-Met inhibitors in blocking tumor cell streaming and metastasis in vivo, and for use in human trials. PMID:27893712

The Calcium-binding Proteins S100A8 and S100A9 Initiate the Early Inflammatory Program in Injured Peripheral Nerves*

PubMed Central

Chernov, Andrei V.; Dolkas, Jennifer; Hoang, Khang; Angert, Mila; Srikrishna, Geetha; Vogl, Thomas; Baranovskaya, Svetlana; Strongin, Alex Y.; Shubayev, Veronica I.

2015-01-01

To shed light on the early immune response processes in severed peripheral nerves, we performed genome-wide transcriptional profiling and bioinformatics analyses of the proximal (P, regenerating) and distal (D, degenerating) nerve stumps on day 1 in the sciatic nerve axotomy model in rats. Multiple cell death-related pathways were activated in the degenerating D stump, whereas activation of the cytoskeletal motility and gluconeogenesis/glycolysis pathways was most prominent in the P stump of the axotomized nerve. Our bioinformatics analyses also identified the specific immunomodulatory genes of the chemokine, IL, TNF, MHC, immunoglobulin-binding Fc receptor, calcium-binding S100, matrix metalloproteinase, tissue inhibitor of metalloproteinase, and ion channel families affected in both the P and D segments. S100a8 and S100a9 were the top up-regulated genes in both the P and D segments. Stimulation of cultured Schwann cells using the purified S100A8/A9 heterodimer recapitulated activation of the myeloid cell and phagocyte chemotactic genes and pathways, which we initially observed in injured nerves. S100A8/A9 heterodimer injection into the intact nerve stimulated macrophage infiltration. We conclude that, following peripheral nerve injury, an immediate acute immune response occurs both distal and proximal to the lesion site and that the rapid transcriptional activation of the S100a8 and S100a9 genes results in S100A8/A9 hetero- and homodimers, which stimulate the release of chemokines and cytokines by activated Schwann cells and generate the initial chemotactic gradient that guides the transmigration of hematogenous immune cells into the injured nerve. PMID:25792748

Polylysine as a functional biopolymer to couple gold nanorods to tumor-tropic cells.

PubMed

Borri, Claudia; Centi, Sonia; Ratto, Fulvio; Pini, Roberto

2018-05-31

The delivery of plasmonic particles, such as gold nanorods, to the tumor microenvironment has attracted much interest in biomedical optics for topical applications as the photoacoustic imaging and photothermal ablation of cancer. However, the systemic injection of free particles still crashes into a complexity of biological barriers, such as the reticuloendothelial system, that prevent their efficient biodistribution. In this context, the notion to exploit the inherent features of tumor-tropic cells for the creation of a Trojan horse is emerging as a plausible alternative. We report on a convenient approach to load cationic gold nanorods into murine macrophages that exhibit chemotactic sensitivity to track gradients of inflammatory stimuli. In particular, we compare a new model of poly-L-lysine-coated particles against two alternatives of cationic moieties that we have presented elsewhere, i.e. a small quaternary ammonium compound and an arginine-rich cell-penetrating peptide. Murine macrophages that are exposed to poly-L-lysine-coated gold nanorods at a dosage of 400 µM Au for 24 h undertake efficient uptake, i.e. around 3 pg Au per cell, retain the majority of their cargo until 24 h post-treatment and maintain around 90% of their pristine viability, chemotactic and pro-inflammatory functions. With respect to previous models of cationic coatings, poly-L-lysine is a competitive solution for the preparation of biological vehicles of gold nanorods, especially for applications that may require longer life span of the Trojan horse, say in the order of 24 h. This biopolymer combines the cost-effectiveness of small molecules and biocompatibility and efficiency of natural peptides and thus holds potential for translational developments.

Tumour related inhibition of macrophage chemotaxis in patients with colon cancer.

PubMed Central

Hermanowicz, A; Gibson, P R; Jewell, D P

1987-01-01

The chemotactic migration in vitro of peripheral blood, intestinal mucosal, and mesenteric lymph node mononuclear cells has been assessed in patients with colorectal carcinoma. Peripheral blood mononuclear cells of patients exhibited normal chemotaxis. For control patients with non-malignant, non-inflammatory intestinal disease, the chemotaxis of mucosal mononuclear cells was similar to that of autologous peripheral blood mononuclear cells. The chemotactic migration of mucosal mononuclear cells, however, isolated distant from a colon cancer was less than that of autologous peripheral blood mononuclear cells. Chemotactic migration was progressively impaired with increasing closeness to the tumour itself. Chemotaxis of mucosal mononuclear cell was independent of the site of tumour and the Dukes' grading. Mononuclear cells from mesenteric lymph nodes, however, exhibited impaired migration only in patients with Dukes' C tumours. Supernatants of the collagenase digestion of either tumour or adjacent mucosa contained macrophage directed inhibitors of chemotaxis and these inhibitors were not produced by tumour mononuclear cells. The presence of such inhibitors in the digestion supernatants and the demonstration that proximity to the tumour was associated with impaired mononuclear cell motility suggest that the production of macrophage directed chemotactic inhibitors is by colon cancer cells and that this may be occurring in vivo. PMID:3583069

Using optical tweezers to examine the chemotactic force to a single inflammatory cell--eosinophil stimulated by chemoattractants prepared from Toxocara Canis larvae

NASA Astrophysics Data System (ADS)

Shih, Po-Chen; Su, Yi-Jr; Chen, Ke-Min; Jen, Lin-Ni; Liu, Cheng-tzu; Hsu, Long

2005-08-01

Granulocytes are a group of white blood cells belonging to the innate immune system in human and in murine in which eosinophils play an important role in worm infection-induced inflammation. The migration of these cells is well characterized and has been separated into four steps: rolling, adhesion, transendothelial migration, and chemotaxis, however, the physical characteristics of the chemotactic force to eosinophils from worm component remain largely unknown. Note that optical tweezers are featured in the manipulation of a single cell and the measurement of biological forces. Therefore, we propose to use optical tweezers to examine the chemotactic force to a eosinophil from a T. canis lavae preparation in terms of distance during the migration of eosinophil.

Monocyte chemotactic protein-1 attenuates and high-fat diet exacerbates bone loss in mice with pulmonary metastasis of Lewis lung carcinoma

USDA-ARS?s Scientific Manuscript database

Bone can be adversely affected by obesity and cancer-associated complications including wasting. The objective of this study was to determine whether a high-fat diet and a deficiency in monocyte chemotactic protein-1 (MCP-1) altered bone structural defects found in male C57BL/6 mice with Lewis lung...

Novel synthetic analogues of avian β-defensin-12: the role of charge, hydrophobicity, and disulfide bridges in biological functions.

PubMed

Yang, Ming; Zhang, Chunye; Zhang, Michael Z; Zhang, Shuping

2017-02-23

Avian β-defensins (AvBD) possess broad-spectrum antimicrobial, LPS neutralizing and chemotactic properties. AvBD-12 is a chemoattractant for avian immune cells and mammalian dendritic cells (JAWSII) - a unique feature that is relevant to the applications of AvBDs as chemotherapeutic agents in mammalian hosts. To identify the structural components essential to various biological functions, we have designed and evaluated seven AvBD analogues. In the first group of analogues, the three conserved disulfide bridges were eliminated by replacing cysteines with alanine and serine residues, peptide hydrophobicity and charge were increased by changing negatively charged amino acid residues to hydrophobic (AvBD-12A1) or positively charged residues (AvBD-12A2 and AvBD-12A3). All three analogues in this group showed improved antimicrobial activity, though AvBD-12A3, with a net positive charge of +9, hydrophobicity of 40% and a predicted CCR2 binding domain, was the most potent antimicrobial peptide. AvBD-12A3 also retained more than 50% of wild type chemotactic activity. In the second group of analogues (AvBD-12A4 to AvBD-12A6), one to three disulfide bridges were removed via substitution of cysteines with isosteric amino acids. Their antimicrobial activity was compromised and chemotactic activity abolished. The third type of analogue was a hybrid that had the backbone of AvBD-12 and positively charged amino acid residues AvBD-6. The antimicrobial and chemotactic activities of the hybrid resembled that of AvBD-6 and AvBD-12, respectively. While the net positive charge and charge distribution have a dominating effect on the antimicrobial potency of AvBDs, the three conserved disulfide bridges are essential to the chemotactic property and the maximum antimicrobial activity. Analogue AvBD-12A3 with a high net positive charge, a moderate degree of hydrophobicity and a CCR2-binding domain can serve as a template for the design of novel antimicrobial peptides with chemotactic property and salt resistance.

Osteoprotegerin in bone metastases: mathematical solution to the puzzle.

PubMed

Ryser, Marc D; Qu, Yiding; Komarova, Svetlana V

2012-01-01

Bone is a common site for cancer metastasis. To create space for their growth, cancer cells stimulate bone resorbing osteoclasts. Cytokine RANKL is a key osteoclast activator, while osteoprotegerin (OPG) is a RANKL decoy receptor and an inhibitor of osteoclastogenesis. Consistently, systemic application of OPG decreases metastatic tumor burden in bone. However, OPG produced locally by cancer cells was shown to enhance osteolysis and tumor growth. We propose that OPG produced by cancer cells causes a local reduction in RANKL levels, inducing a steeper RANKL gradient away from the tumor and towards the bone tissue, resulting in faster resorption and tumor expansion. We tested this hypothesis using a mathematical model of nonlinear partial differential equations describing the spatial dynamics of OPG, RANKL, PTHrP, osteoclasts, tumor and bone mass. We demonstrate that at lower expression rates, tumor-derived OPG enhances the chemotactic RANKL gradient and osteolysis, whereas at higher expression rates OPG broadly inhibits RANKL and decreases osteolysis and tumor burden. Moreover, tumor expression of a soluble mediator inducing RANKL in the host tissue, such as PTHrP, is important for correct orientation of the RANKL gradient. A meta-analysis of OPG, RANKL and PTHrP expression in normal prostate, carcinoma and metastatic tissues demonstrated an increase in expression of OPG, but not RANKL, in metastatic prostate cancer, and positive correlation between OPG and PTHrP in metastatic prostate cancer. The proposed mechanism highlights the importance of the spatial distribution of receptors, decoys and ligands, and can be applied to other systems involving regulation of spatially anisotropic processes.

Modification of β-Defensin-2 by Dicarbonyls Methylglyoxal and Glyoxal Inhibits Antibacterial and Chemotactic Function In Vitro.

PubMed

Kiselar, Janna G; Wang, Xiaowei; Dubyak, George R; El Sanadi, Caroline; Ghosh, Santosh K; Lundberg, Kathleen; Williams, Wesley M

2015-01-01

Beta-defensins (hBDs) provide antimicrobial and chemotactic defense against bacterial, viral and fungal infections. Human β-defensin-2 (hBD-2) acts against gram-negative bacteria and chemoattracts immature dendritic cells, thus regulating innate and adaptive immunity. Immunosuppression due to hyperglycemia underlies chronic infection in Type 2 diabetes. Hyperglycemia also elevates production of dicarbonyls methylgloxal (MGO) and glyoxal (GO). The effect of dicarbonyl on defensin peptide structure was tested by exposing recombinant hBD-2 (rhBD-2) to MGO or GO with subsequent analysis by MALDI-TOF MS and LC/MS/MS. Antimicrobial function of untreated rhBD-2 vs. rhBD-2 exposed to dicarbonyl against strains of both gram-negative and gram-positive bacteria in culture was determined by radial diffusion assay. The effect of dicarbonyl on rhBD-2 chemotactic function was determined by chemotaxis assay in CEM-SS cells. MGO or GO in vitro irreversibly adducts to the rhBD-2 peptide, and significantly reduces antimicrobial and chemotactic functions. Adducts derive from two arginine residues, Arg22 and Arg23 near the C-terminus, and the N-terminal glycine (Gly1). We show by radial diffusion testing on gram-negative E. coli and P. aeruginosa, and gram-positive S. aureus, and a chemotaxis assay for CEM-SS cells, that antimicrobial activity and chemotactic function of rhBD-2 are significantly reduced by MGO. Dicarbonyl modification of cationic antimicrobial peptides represents a potential link between hyperglycemia and the clinical manifestation of increased susceptibility to infection, protracted wound healing, and chronic inflammation in undiagnosed and uncontrolled Type 2 diabetes.

Chemotactic signal integration in bacteria.

PubMed Central

Khan, S; Spudich, J L; McCray, J A; Trentham, D R

1995-01-01

Chemotactic signaling in Escherichia coli involves transmission of both negative and positive signals. In order to examine mechanisms of signal processing, behavioral responses to dual inputs have been measured by using photoactivable "caged" compounds, computer video analysis, and chemoreceptor deletion mutants. Signaling from Tar and Tsr, two receptors that sense amino acids and pH, was studied. In a Tar deletion mutant the photoactivated release of protons, a Tsr repellent, and of serine, a Tsr attractant, in separate experiments at pH 7.0 resulted in tumbling (negative) or smooth-swimming (positive) responses in ca. 50 and 140 ms, respectively. Simultaneous photorelease of protons and serine resulted in a single tumbling or smooth-swimming response, depending on the relative amounts of the two effectors. In contrast, in wild-type E. coli, proton release at pH 7.0 resulted in a biphasic response that was attributed to Tsr-mediated tumbling followed by Tar-mediated smooth-swimming. In wild-type E. coli at more alkaline pH values the Tar-mediated signal was stronger than the Tsr signal, resulting in a strong smooth-swimming response preceded by a diminished tumbling response. These observations imply that (i) a single receptor time-averages the binding of different chemotactic ligands generating a single response; (ii) ligand binding to different receptors can result in a nonintegrated response with the tumbling response preceding the smooth-swimming response; (iii) however, chemotactic signals of different intensities derived from different receptors can also result in an apparently integrated response; and (iv) the different chemotactic responses to protons at neutral and alkaline pH may contribute to E. coli migration toward neutrality. Images Fig. 6 PMID:7568212

Epigenetic Regulation of Chermokine Expression in Prostate Cancer

DTIC Science & Technology

2008-12-01

Chemotactic potential of CXCL14 for human DC Recently, we demonstrated that CXCL14 and CXCL14-positive HNSCC ( Head and Neck Squamouse Cell...insights into the functional interaction between DC and neoplastic cells, we proposed to analyze the effects of PCa on the chemotaxis of human DC in...vitro and in vivo. Our Specific Aims were: 1. Characterize chemotactic activity of CXCL14 towards human DC in vitro. 2. Examine whether restoration of

Activation of the complement system in patients with porphyrias after irradiation in vivo.

PubMed Central

Lim, H W; Poh-Fitzpatrick, M B; Gigli, I

1984-01-01

Irradiation of the forearms of two patients with erythropoietic protoporphyria and one patient with porphyria cutanea tarda resulted in an in vivo activation of the complement system, as assessed by diminution of the hemolytic titers of the third component of complement by 23-57%, and of the fifth component of complement (C5) by 19-47%. Such treatment also generated chemotactic activity for human polymorphonuclear cells; the chemotactic activity was stable at 56 degrees C and antigenically related to human C5. On Sephadex G-75 chromatography the chemotactic activity eluted with an apparent molecular weight of 15,000. These in vivo results extend our previous in vitro observation of photoactivation of complement in sera from patients with erythropoietic protoporphyria and porphyria cutanea tarda, and suggest that the complement system may participate in the pathogenesis of cutaneous phototoxicity in these patients. PMID:6392339

Fluorescent staining for leukocyte chemotaxis. Eosinophil-specific fluorescence with aniline blue.

PubMed

McCrone, E L; Lucey, D R; Weller, P F

1988-11-10

To overcome problems associated with the quantitation of human eosinophil chemotaxis in micropore filters, we have developed a fluorescent method of specifically staining eosinophils in chemotactic filters. A neutral solution of aniline blue yielded bright green fluorescent staining of the cytoplasmic granules of eosinophils. Other leukocytes and contaminating neutrophils potentially present with eosinophils did not fluoresce with aniline blue. The fluorescent staining eosinophils within filters provided bright, non-fading images that facilitated visual microscopic counting and were of sufficiently high contrast, unlike those with conventional eosinophil stains, to allow image analyzer based enumeration of eosinophil chemotactic responses at levels through the filters. Although not cell type-specific, congo red and ethidium bromide also provided high contrast, fluorescent images of all leukocyte types within chemotactic filters. Fluorescent staining with aniline blue constitutes a rapid, stable and eosinophil-specific stain that facilitates the visual or image analyzer-based quantitation of eosinophil chemotaxis.

Caffeine, dibutyryl cyclic-AMP and heparin affect the chemotactic and phagocytotic activities of neutrophils for boar sperm in vitro.

PubMed

Li, J-C; Yamaguchi, S; Kondo, Y; Funahashi, H

2011-04-15

The objective was to examine the effects of caffeine, dibutyryl cyclic AMP, and heparin on the chemotaxis and/or phagocytosis of PMNs for porcine sperm. The chemotactic activity of PMNs, determined in a blind well chamber, increased (P < 0.05) when fresh serum was added to the medium (control containing BSA, 1109.5 cells/mm(2) vs serum, 1226.3 cells/mm(2)), regardless of the presence of sperm (control, 1121.1 cells/mm(2) vs serum, 1245.8 cells/mm(2)), whereas heat-inactivated serum did not affect activity (without sperm, 1099.4 cells/mm(2) and with sperm, 1132.6 cells/mm(2)). Regardless of live and dead sperm and of the origin of PMNs (boars vs sows), the phagocytotic activity of PMNs, as determined by co-culture of PMNs with sperm for 60 min, increased (P < 0.05) in the presence of fresh serum containing active complement (46.7 and 43.0%, respectively), but stimulation was decreased (P < 0.05) when 1 mM or higher concentrations of caffeine was added to the medium (from 40.7 to 20.8-31.6%). The origin of PMNs (sows vs boars) did not significantly affect phagocytotic activity. The percentage of PMNs that phagocytized polystyrene latex beads decreased when 2 mM caffeine was added to the medium containing porcine serum (from 43.7 to 21.5%). Serum-stimulated chemotactic activity of PMNs (1089.9 cells/mm(2)) was also reduced (P < 0.05) with 2 mM caffeine (942.5 cells/mm(2)). Furthermore, dibutyryl cAMP at ≥ 0.1 mM or heparin at ≥ 100 μg/mL decreased phagocytotic activity, in a concentration-dependent manner (P < 0.05). Supplementation of PMNs with heparin at 100 or 500 μg/mL decreased (P < 0.05) chemotactic activity in the presence of serum (from 1137.1 cells/mm(2) to 1008.8-1026.3 cells/mm(2)). We inferred that opsonization in the presence of active complement stimulated phagocytotic and chemotactic activities of PMNs, whereas supplementation with caffeine and dibutyryl cAMP (which could be associated with the intracellular cAMP level of PMNs) or adding heparin decreased serum-stimulated phagocytotic and chemotactic activities. Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.

Computational model of mesenchymal migration in 3D under chemotaxis.

PubMed

Ribeiro, F O; Gómez-Benito, M J; Folgado, J; Fernandes, P R; García-Aznar, J M

2017-01-01

Cell chemotaxis is an important characteristic of cellular migration, which takes part in crucial aspects of life and development. In this work, we propose a novel in silico model of mesenchymal 3D migration with competing protrusions under a chemotactic gradient. Based on recent experimental observations, we identify three main stages that can regulate mesenchymal chemotaxis: chemosensing, dendritic protrusion dynamics and cell-matrix interactions. Therefore, each of these features is considered as a different module of the main regulatory computational algorithm. The numerical model was particularized for the case of fibroblast chemotaxis under a PDGF-bb gradient. Fibroblasts migration was simulated embedded in two different 3D matrices - collagen and fibrin - and under several PDGF-bb concentrations. Validation of the model results was provided through qualitative and quantitative comparison with in vitro studies. Our numerical predictions of cell trajectories and speeds were within the measured in vitro ranges in both collagen and fibrin matrices. Although in fibrin, the migration speed of fibroblasts is very low, because fibrin is a stiffer and more entangling matrix. Testing PDGF-bb concentrations, we noticed that an increment of this factor produces a speed increment. At 1 ng mL -1 a speed peak is reached after which the migration speed diminishes again. Moreover, we observed that fibrin exerts a dampening behavior on migration, significantly affecting the migration efficiency.

Role of Progesterone Receptor Isoforms in Regulation of Cell Adhesion and Apoptosis

DTIC Science & Technology

2002-06-01

repeatable) (figure 1 below). We used taxol to induce apoptosis instead of tumor necrosis factor (TNF) (as initially proposed in the grant) because...highlighted in red in Fig. 6A), monocyte chemotactic protein (MCP; open arrow in Fig. 6A and isolated in Fig. 6B, top) and bullous pemphigoid antigen...red. The open arrow indicates monocyte chemotactic protein (MCP) and closed arrow indi- cates bullous pemphigoid antigen (BPAG). B, top, isolated

Swimming pattern of Pseudomonas putida - navigating with stops and reversals

NASA Astrophysics Data System (ADS)

Hintsche, Marius; Waljor, Veronika; Alirezaeizanjani, Zahra; Theves, Matthias; Beta, Carsten

Bacterial swimming strategies depend on factors such as the chemical and physical environment, as well as the flagellation pattern of a species. For some bacteria the motility pattern and the underlying flagellar dynamics are well known, such as the classical run-and-tumble behavior of E. coli. Here we study the swimming motility and chemotactic behavior of the polar, multi-flagellated soil dwelling bacterium Pseudomonas putida. Compared to E. coli, its motility pattern is more diverse. In addition to different speed levels, P. putida exhibits two types of reorientation events, stops and reversals, the occurrence of which is modulated according to the growth conditions. We also analyzed the swimming pattern in the presence of chemical gradients. Using benzoate as a chemoattractant, we measured key motility parameters in order to characterize P. putida's chemotaxis strategy and to quantify the directional bias in its random walk. Our results indicate a change in the reversal frequency depending on changes in the chemoattractant concentration consistent with the classical scenario of temporal sensing. DFG.

Lymphocyte Electrotaxis in vitro and in vivo

PubMed Central

Lin, Francis; Baldessari, Fabio; Gyenge, Christina Crenguta; Sato, Tohru; Chambers, Robert D.; Santiago, Juan G.; Butcher, Eugene C.

2008-01-01

Electric fields are generated in vivo in a variety of physiologic and pathologic settings, including penetrating injury to epithelial barriers. An applied electric field with strength within the physiologic range can induce directional cell migration (i.e. electrotaxis) of epithelial cells, endothelial cells, fibroblasts, and neutrophils suggesting a potential role in cell positioning during wound healing. In the present study, we investigated the ability of lymphocytes to respond to applied direct current (DC) electric fields. Using a modified transwell assay and a simple microfluidic device, we show that human peripheral blood lymphocytes migrate toward the cathode in physiologically relevant DC electric fields. Additionally, electrical stimulation activates intracellular kinase signaling pathways shared with chemotactic stimuli. Finally, video microscopic tracing of GFP-tagged immunocytes in the skin of mouse ears reveals that motile cutaneous T cells actively migrate toward the cathode of an applied DC electric field. Lymphocyte positioning within tissues can thus be manipulated by externally applied electric fields, and may be influenced by endogenous electrical potential gradients as well. PMID:18684937

Lymphocyte electrotaxis in vitro and in vivo.

PubMed

Lin, Francis; Baldessari, Fabio; Gyenge, Christina Crenguta; Sato, Tohru; Chambers, Robert D; Santiago, Juan G; Butcher, Eugene C

2008-08-15

Electric fields are generated in vivo in a variety of physiologic and pathologic settings, including penetrating injury to epithelial barriers. An applied electric field with strength within the physiologic range can induce directional cell migration (i.e., electrotaxis) of epithelial cells, endothelial cells, fibroblasts, and neutrophils suggesting a potential role in cell positioning during wound healing. In the present study, we investigated the ability of lymphocytes to respond to applied direct current (DC) electric fields. Using a modified Transwell assay and a simple microfluidic device, we show that human PBLs migrate toward the cathode in physiologically relevant DC electric fields. Additionally, electrical stimulation activates intracellular kinase signaling pathways shared with chemotactic stimuli. Finally, video microscopic tracing of GFP-tagged immunocytes in the skin of mouse ears reveals that motile cutaneous T cells actively migrate toward the cathode of an applied DC electric field. Lymphocyte positioning within tissues can thus be manipulated by externally applied electric fields, and may be influenced by endogenous electrical potential gradients as well.

Disruption of Chemoreceptor Signaling Arrays by High Levels of CheW, the Receptor-Kinase Coupling Protein

PubMed Central

Cardozo, Marcos J.; Massazza, Diego A.; Parkinson, John S.; Studdert, Claudia A.

2017-01-01

Summary During chemotactic signaling by Escherichia coli, the small cytoplasmic CheW protein couples the histidine kinase CheA to chemoreceptor control. Although essential for assembly and operation of receptor signaling complexes, CheW in stoichiometric excess disrupts chemotactic behavior. To explore the mechanism of the CheW excess effect, we measured the physiological consequences of high cellular levels of wild-type CheW and of several CheW variants with reduced or enhanced binding affinities for receptor molecules. We found that high levels of CheW interfered with trimer assembly, prevented CheA activation, blocked cluster formation, disrupted chemotactic ability, and elevated receptor methylation levels. The severity of these effects paralleled the receptor binding affinities of the CheW variants. Because trimer formation may be an obligate step in the assembly of ternary signaling complexes and higher-order receptor arrays, we suggest that all CheW excess effects stem from disruption of trimer assembly. We propose that the CheW-binding sites in receptor dimers overlap their trimer contact sites and that high levels of CheW saturate the receptor binding sites, preventing trimer assembly. The CheW-trapped receptor dimers seem to be improved substrates for methyltransferase reactions, but cannot activate CheA or assemble into clusters, processes that are essential for chemotactic signaling. PMID:20487303

Expression of EMAP-II in the rat dental follicle and its potential role in tooth eruption

PubMed Central

Liu, Dawen; Wise, Gary E.

2008-01-01

Endothelial monocyte-activating polypeptide II (EMAP-II) is an inflammatory cytokine with chemotactic activity. Because the dental follicle (DF) recruits mononuclear cells (osteoclast precursors) to promote the osteoclastogenesis needed for tooth eruption, it was the aim of this study to determine if EMAP-II may contribute to this recruitment. Using a DNA microarray, EMAP-II was found to be highly expressed in vivo in the DFs of day 1 to day 11 postnatal rats, with its expression elevated at days 1 and 3. Using a siRNA to knock down EMAP-II expression also resulted in a reduction in expression of CSF-1 and MCP-1 in the DF cells. Addition of EMAP-II protein to the DF cells partially restored the expression of CSF-1 and MCP-1. In chemotaxis assays using either conditioned medium of the DF cells with anti-EMAP-II antibody added or conditioned medium of DF cells with EMAP-II knocked down by siRNA, migration indexes of bone marrow mononuclear cells were significantly reduced. These results suggest that EMAP-II is another chemotactic molecule in the dental follicle involved in recruitment of mononuclear cells, and that EMAP-II may exert its chemotactic function directly by recruiting mononuclear cells and indirectly by enhancing the expression of other chemotactic molecules (CSF-1 and MCP-1). PMID:18705801

Plant-Adapted Escherichia coli Show Increased Lettuce Colonizing Ability, Resistance to Oxidative Stress and Chemotactic Response

PubMed Central

Dublan, Maria de los Angeles; Ortiz-Marquez, Juan Cesar Federico; Lett, Lina; Curatti, Leonardo

2014-01-01

Background Escherichia coli is a widespread gut commensal and often a versatile pathogen of public health concern. E. coli are also frequently found in different environments and/or alternative secondary hosts, such as plant tissues. The lifestyle of E. coli in plants is poorly understood and has potential implications for food safety. Methods/Principal Findings This work shows that a human commensal strain of E. coli K12 readily colonizes lettuce seedlings and produces large microcolony-like cell aggregates in leaves, especially in young leaves, in proximity to the vascular tissue. Our observations strongly suggest that those cell aggregates arise from multiplication of single bacterial cells that reach those spots. We showed that E. coli isolated from colonized leaves progressively colonize lettuce seedlings to higher titers, suggesting a fast adaptation process. E. coli cells isolated from leaves presented a dramatic rise in tolerance to oxidative stress and became more chemotactic responsive towards lettuce leaf extracts. Mutant strains impaired in their chemotactic response were less efficient lettuce colonizers than the chemotactic isogenic strain. However, acclimation to oxidative stress and/or minimal medium alone failed to prime E. coli cells for enhanced lettuce colonization efficiency. Conclusion/Significance These findings help to understand the physiological adaptation during the alternative lifestyle of E. coli in/on plant tissues. PMID:25313845

Structure-function analysis of Avian β-defensin-6 and β-defensin-12: role of charge and disulfide bridges.

PubMed

Yang, Ming; Zhang, Chunye; Zhang, Xuehan; Zhang, Michael Z; Rottinghaus, George E; Zhang, Shuping

2016-09-09

Avian beta-defensins (AvBD) are small, cationic, antimicrobial peptides. The potential application of AvBDs as alternatives to antibiotics has been the subject of interest. However, the mechanisms of action remain to be fully understood. The present study characterized the structure-function relationship of AvBD-6 and AvBD-12, two peptides with different net positive charges, similar hydrophobicity and distinct tissue expression profiles. AvBD-6 was more potent than AvBD-12 against E. coli, S. Typhimurium, and S. aureus as well as clinical isolates of extended spectrum beta lactamase (ESBL)-positive E. coli and K. pneumoniae. AvBD-6 was more effective than AvBD-12 in neutralizing LPS and interacting with bacterial genomic DNA. Increasing bacterial concentration from 10(5) CFU/ml to 10(9) CFU/ml abolished AvBDs' antimicrobial activity. Increasing NaCl concentration significantly inhibited AvBDs' antimicrobial activity, but not the LPS-neutralizing function. Both AvBDs were mildly chemotactic for chicken macrophages and strongly chemotactic for CHO-K1 cells expressing chicken chemokine receptor 2 (CCR2). AvBD-12 at higher concentrations also induced chemotactic migration of murine immature dendritic cells (DCs). Disruption of disulfide bridges abolished AvBDs' chemotactic activity. Neither AvBDs was toxic to CHO-K1, macrophages, or DCs. AvBDs are potent antimicrobial peptides under low-salt conditions, effective LPS-neutralizing agents, and broad-spectrum chemoattractant peptides. Their antimicrobial activity is positively correlated with the peptides' net positive charges, inversely correlated with NaCl concentration and bacterial concentration, and minimally dependent on intramolecular disulfide bridges. In contrast, their chemotactic property requires the presence of intramolecular disulfide bridges. Data from the present study provide a theoretical basis for the design of AvBD-based therapeutic and immunomodulatory agents.

The group VIA calcium-independent phospholipase A2 and NFATc4 pathway mediates IL-1β-induced expression of chemokines CCL2 and CXCL10 in rat fibroblasts.

PubMed

Kuwata, Hiroshi; Yuzurihara, Chihiro; Kinoshita, Natsumi; Taki, Yuki; Ikegami, Yuki; Washio, Sana; Hirakawa, Yushi; Yoda, Emiko; Aiuchi, Toshihiro; Itabe, Hiroyuki; Nakatani, Yoshihito; Hara, Shuntaro

2018-06-01

Chemokines are secreted proteins that regulate cell migration and are involved in inflammatory and immune responses. Here, we sought to define the functional crosstalk between the lipid signaling and chemokine signaling. We obtained evidence that the induction of some chemokines is regulated by group VIA calcium-independent phospholipase A 2 β (iPLA 2 β) in IL-1β-stimulated rat fibroblastic 3Y1 cells. Treatment of 3Y1 cells with IL-1β elicited an increased release of chemotactic factor(s) for monocytic THP-1 cells into culture medium in a time-dependent manner. Inhibitor studies revealed that an intracellular PLA 2 inhibitor, arachidonoyl trifluoromethyl ketone (AACOCF 3 ), but not the cyclooxygenase inhibitor indomethacin, attenuated the release of chemotactic factor(s). The chemotactic activity was inactivated by treatment with either heat or proteinase K, suggesting this chemotactic factor(s) is a proteinaceous factor(s). We purified the chemotactic factor(s) from the conditioned medium of IL-1β-stimulated 3Y1 cells using a heparin column and identified several chemokines, including CCL2 and CXCL10. The inducible expressions of CCL2 and CXCL10 were significantly attenuated by pretreatment with AACOCF 3 . Gene silencing using siRNA revealed that the inductions of CCL2 and CXCL10 were attenuated by iPLA 2 β knockdown. Additionally, the transcriptional activation of nuclear factor of activated T-cell proteins (NFATs), but not nuclear factor-κB, by IL-1β stimulation was markedly attenuated by the iPLA 2 inhibitor bromoenol lactone, and NFATc4 knockdown markedly attenuated the IL-1β-induced expression of both CCL2 and CXCL10. Collectively, these results indicated that iPLA 2 β plays roles in IL-1β-induced chemokine expression, in part via NFATc4 signaling. © 2018 Federation of European Biochemical Societies.

A novel neutrophil-activating factor released by Trichomonas vaginalis.

PubMed Central

Shaio, M F; Lin, P R; Lee, C S; Hou, S C; Tang, P; Yang, K D

1992-01-01

We have investigated the effects of a novel neutrophil-activating factor released by Trichomonas vaginalis (TV-NAF) on neutrophil chemotaxis. TV-NAF was present in the supernatant from 10(7) T. vaginalis (STV) cultured in 1 ml of serum-free Hanks' balanced salt solution (HBSS) at 37 degrees C for 30 min. With a multichamber chemotactic assay, we found that there were 112 +/- 15 migrated neutrophils (mean +/- standard deviation, n = 7) for STV and 11 +/- 4 for HBSS per high-power field (x 400). STV was also able to induce neutrophil actin assembly (increased 1.5-fold), enhance expression of complement receptor type 3 (increased 5-fold), and promote intracellular calcium mobilization (increased 2.5-fold). There was no chemotactic activity in the preparation of STV from killed trichomonads. The fact that heating up to 100 degrees C or deproteinization by treatment with proteinase K at 65 degrees C for 1 h did not abolish its chemotactic activity suggests that the TV-NAF involved was not a protein. The chemotactic activity of TV-NAF was associated with the fraction containing small molecules of less than 3,000 Da. Therefore, the possibility that eicosanoid production by trichomonads is responsible for neutrophil activation was investigated. Leukotriene B4 (LTB4; 500 pg/ml) but not thromboxane B2 (< 20 pg/ml) or prostaglandin E2 (< 8 pg/ml) was found in the STV by radioimmunoassay. Production of LTB4 by trichomonads was time dependent and increased twofold when arachidonic acid (100 microM) was added but was not decreased when eicosanoid inhibitors were present. Evidence for the presence of LTB4 in STV was further provided by the fact that rabbit anti-LTB4 antiserum could abolish the chemotactic activity of STV. These studies suggest that the spontaneous release of TV-NAF, which is most likely LTB4, may activate neutrophils, presumably through a different arachidonate metabolic pathway than that in mammalian cells. PMID:1398962

Association of Urinary Biomarkers of Inflammation, Injury, and Fibrosis with Renal Function Decline: The ACCORD Trial

PubMed Central

Nadkarni, Girish N.; Rao, Veena; Ismail-Beigi, Faramarz; Fonseca, Vivian A.; Shah, Sudhir V.; Simonson, Michael S.; Cantley, Lloyd; Devarajan, Prasad; Parikh, Chirag R.

2016-01-01

Background and objectives Current measures for predicting renal functional decline in patients with type 2 diabetes with preserved renal function are unsatisfactory, and multiple markers assessing various biologic axes may improve prediction. We examined the association of four biomarker-to-creatinine ratio levels (monocyte chemotactic protein-1, IL-18, kidney injury molecule-1, and YKL-40) with renal outcome. Design, setting, participants, & measurements We used a nested case-control design in the Action to Control Cardiovascular Disease Trial by matching 190 participants with ≥40% sustained eGFR decline over the 5-year follow-up period to 190 participants with ≤10% eGFR decline in a 1:1 fashion on key characteristics (age within 5 years, sex, race, baseline albumin-to-creatinine ratio within 20 μg/mg, and baseline eGFR within 10 ml/min per 1.73 m2), with ≤10% decline. We used a Mesoscale Multiplex Platform and measured biomarkers in baseline and 24-month specimens, and we examined biomarker associations with outcome using conditional logistic regression. Results Baseline and 24-month levels of monocyte chemotactic protein-1-to-creatinine ratio levels were higher for cases versus controls. The highest quartile of baseline monocyte chemotactic protein-1-to-creatinine ratio had fivefold greater odds, and each log increment had 2.27-fold higher odds for outcome (odds ratio, 5.27; 95% confidence interval, 2.19 to 12.71 and odds ratio, 2.27; 95% confidence interval, 1.44 to 3.58, respectively). IL-18-to-creatinine ratio, kidney injury molecule-1-to-creatinine ratio, and YKL-40-to-creatinine ratio were not consistently associated with outcome. C statistic for traditional predictors of eGFR decline was 0.70, which improved significantly to 0.74 with monocyte chemotactic protein-1-to-creatinine ratio. Conclusions Urinary monocyte chemotactic protein-1-to-creatinine ratio concentrations were strongly associated with sustained renal decline in patients with type 2 diabetes with preserved renal function. PMID:27189318

Association of Urinary Biomarkers of Inflammation, Injury, and Fibrosis with Renal Function Decline: The ACCORD Trial.

PubMed

Nadkarni, Girish N; Rao, Veena; Ismail-Beigi, Faramarz; Fonseca, Vivian A; Shah, Sudhir V; Simonson, Michael S; Cantley, Lloyd; Devarajan, Prasad; Parikh, Chirag R; Coca, Steven G

2016-08-08

Current measures for predicting renal functional decline in patients with type 2 diabetes with preserved renal function are unsatisfactory, and multiple markers assessing various biologic axes may improve prediction. We examined the association of four biomarker-to-creatinine ratio levels (monocyte chemotactic protein-1, IL-18, kidney injury molecule-1, and YKL-40) with renal outcome. We used a nested case-control design in the Action to Control Cardiovascular Disease Trial by matching 190 participants with ≥40% sustained eGFR decline over the 5-year follow-up period to 190 participants with ≤10% eGFR decline in a 1:1 fashion on key characteristics (age within 5 years, sex, race, baseline albumin-to-creatinine ratio within 20 μg/mg, and baseline eGFR within 10 ml/min per 1.73 m(2)), with ≤10% decline. We used a Mesoscale Multiplex Platform and measured biomarkers in baseline and 24-month specimens, and we examined biomarker associations with outcome using conditional logistic regression. Baseline and 24-month levels of monocyte chemotactic protein-1-to-creatinine ratio levels were higher for cases versus controls. The highest quartile of baseline monocyte chemotactic protein-1-to-creatinine ratio had fivefold greater odds, and each log increment had 2.27-fold higher odds for outcome (odds ratio, 5.27; 95% confidence interval, 2.19 to 12.71 and odds ratio, 2.27; 95% confidence interval, 1.44 to 3.58, respectively). IL-18-to-creatinine ratio, kidney injury molecule-1-to-creatinine ratio, and YKL-40-to-creatinine ratio were not consistently associated with outcome. C statistic for traditional predictors of eGFR decline was 0.70, which improved significantly to 0.74 with monocyte chemotactic protein-1-to-creatinine ratio. Urinary monocyte chemotactic protein-1-to-creatinine ratio concentrations were strongly associated with sustained renal decline in patients with type 2 diabetes with preserved renal function. Copyright © 2016 by the American Society of Nephrology.

Molecular characteristics, biofilm-forming abilities, and quorum sensing molecules in Vibrio parahaemolyticus strains isolated from marine and clinical environments in Korea.

PubMed

Mizan, Md Furkanur Rahaman; Bang, Hyeon-Jo; Sadekuzzaman, Mohammad; Lee, Nari; Kim, Tae-Jo; Ha, Sang-Do

2017-05-01

Vibrio parahaemolyticus is an inhabitant of marine and estuarine environments and causes seafood-borne gastroenteritis in humans. In this study, an UltraFast LabChip Real-Time PCR assay was evaluated for rapid detection and quantification of pathogenic V. parahaemolyticus isolates. Escherichia coli and Vibrio harveyi were used as negative controls. Twenty-six tdh-positive, biofilm-producing V. parahaemolyticus isolates were analyzed by repetitive extragenic palindromic-polymerase chain reaction (REP-PCR). REP-PCR analysis showed that the majority of the V. parahaemolyticus isolates originated from seafood and that clinical specimens formed two major clusters at 92.8% and 32% similarity levels. The presence and quantification of Autoinducer-2 was carried out using high-performance liquid chromatography with fluorescence detection (HPLC-FLD) after derivatization of Autoinducer-2 with 2, 3-diaminonaphthalene. The presence of tdh-positive V. parahaemolyticus in marine samples highlights the need for constant environmental monitoring to protect public health.

Macrolactone Nuiapolide, Isolated from a Hawaiian Marine Cyanobacterium, Exhibits Anti-Chemotactic Activity.

PubMed

Mori, Shogo; Williams, Howard; Cagle, Davey; Karanovich, Kristopher; Horgen, F David; Smith, Roger; Watanabe, Coran M H

2015-10-09

A new bioactive macrolactone, nuiapolide (1) was identified from a marine cyanobacterium collected off the coast of Niihau, near Lehua Rock. The natural product exhibits anti-chemotactic activity at concentrations as low as 1.3 μM against Jurkat cells, cancerous T lymphocytes, and induces a G2/M phase cell cycle shift. Structural characterization of the natural product revealed the compound to be a 40-membered macrolactone with nine hydroxyl functional groups and a rare tert-butyl carbinol residue.

Macrolactone Nuiapolide, Isolated from a Hawaiian Marine Cyanobacterium, Exhibits Anti-Chemotactic Activity

PubMed Central

Mori, Shogo; Williams, Howard; Cagle, Davey; Karanovich, Kristopher; Horgen, F. David; Smith, Roger; Watanabe, Coran M. H.

2015-01-01

A new bioactive macrolactone, nuiapolide (1) was identified from a marine cyanobacterium collected off the coast of Niihau, near Lehua Rock. The natural product exhibits anti-chemotactic activity at concentrations as low as 1.3 μM against Jurkat cells, cancerous T lymphocytes, and induces a G2/M phase cell cycle shift. Structural characterization of the natural product revealed the compound to be a 40-membered macrolactone with nine hydroxyl functional groups and a rare tert-butyl carbinol residue. PMID:26473885

A Trigger Residue for Transmembrane Signaling in the Escherichia coli Serine Chemoreceptor.

PubMed

Kitanovic, Smiljka; Ames, Peter; Parkinson, John S

2015-08-01

The transmembrane Tsr protein of Escherichia coli mediates chemotactic responses to environmental serine gradients. Serine binds to the periplasmic domain of the homodimeric Tsr molecule, promoting a small inward displacement of one transmembrane helix (TM2). TM2 piston displacements, in turn, modulate the structural stability of the Tsr-HAMP domain on the cytoplasmic side of the membrane to control the autophosphorylation activity of the signaling CheA kinase bound to the membrane-distal cytoplasmic tip of Tsr. A five-residue control cable segment connects TM2 to the AS1 helix of HAMP and transmits stimulus and sensory adaptation signals between them. To explore the possible role of control cable helicity in transmembrane signaling by Tsr, we characterized the signaling properties of mutant receptors with various control cable alterations. An all-alanine control cable shifted Tsr output toward the kinase-on state, whereas an all-glycine control cable prevented Tsr from reaching either a fully on or fully off output state. Restoration of the native isoleucine (I214) in these synthetic control cables largely alleviated their signaling defects. Single amino acid replacements at Tsr-I214 shifted output toward the kinase-off (L, N, H, and R) or kinase-on (A and G) states, whereas other control cable residues tolerated most amino acid replacements with little change in signaling behavior. These findings indicate that changes in control cable helicity might mediate transitions between the kinase-on and kinase-off states during transmembrane signaling by chemoreceptors. Moreover, the Tsr-I214 side chain plays a key role, possibly through interaction with the membrane interfacial environment, in triggering signaling changes in response to TM2 piston displacements. The Tsr protein of E. coli mediates chemotactic responses to environmental serine gradients. Stimulus signals from the Tsr periplasmic sensing domain reach its cytoplasmic kinase control domain through piston displacements of a membrane-spanning helix and an adjoining five-residue control cable segment. We characterized the signaling properties of Tsr variants to elucidate the transmembrane signaling role of the control cable, an element present in many microbial sensory proteins. Both the kinase-on and kinase-off output states of Tsr depended on control cable helicity, but only one residue, I214, was critical for triggering responses to attractant inputs. These findings suggest that signal transmission in Tsr involves modulation of control cable helicity through interaction of the I214 side chain with the cytoplasmic membrane. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

A Trigger Residue for Transmembrane Signaling in the Escherichia coli Serine Chemoreceptor

PubMed Central

Kitanovic, Smiljka; Ames, Peter

2015-01-01

ABSTRACT The transmembrane Tsr protein of Escherichia coli mediates chemotactic responses to environmental serine gradients. Serine binds to the periplasmic domain of the homodimeric Tsr molecule, promoting a small inward displacement of one transmembrane helix (TM2). TM2 piston displacements, in turn, modulate the structural stability of the Tsr-HAMP domain on the cytoplasmic side of the membrane to control the autophosphorylation activity of the signaling CheA kinase bound to the membrane-distal cytoplasmic tip of Tsr. A five-residue control cable segment connects TM2 to the AS1 helix of HAMP and transmits stimulus and sensory adaptation signals between them. To explore the possible role of control cable helicity in transmembrane signaling by Tsr, we characterized the signaling properties of mutant receptors with various control cable alterations. An all-alanine control cable shifted Tsr output toward the kinase-on state, whereas an all-glycine control cable prevented Tsr from reaching either a fully on or fully off output state. Restoration of the native isoleucine (I214) in these synthetic control cables largely alleviated their signaling defects. Single amino acid replacements at Tsr-I214 shifted output toward the kinase-off (L, N, H, and R) or kinase-on (A and G) states, whereas other control cable residues tolerated most amino acid replacements with little change in signaling behavior. These findings indicate that changes in control cable helicity might mediate transitions between the kinase-on and kinase-off states during transmembrane signaling by chemoreceptors. Moreover, the Tsr-I214 side chain plays a key role, possibly through interaction with the membrane interfacial environment, in triggering signaling changes in response to TM2 piston displacements. IMPORTANCE The Tsr protein of E. coli mediates chemotactic responses to environmental serine gradients. Stimulus signals from the Tsr periplasmic sensing domain reach its cytoplasmic kinase control domain through piston displacements of a membrane-spanning helix and an adjoining five-residue control cable segment. We characterized the signaling properties of Tsr variants to elucidate the transmembrane signaling role of the control cable, an element present in many microbial sensory proteins. Both the kinase-on and kinase-off output states of Tsr depended on control cable helicity, but only one residue, I214, was critical for triggering responses to attractant inputs. These findings suggest that signal transmission in Tsr involves modulation of control cable helicity through interaction of the I214 side chain with the cytoplasmic membrane. PMID:26013490

Saddle-node bifurcation to jammed state for quasi-one-dimensional counter-chemotactic flow.

PubMed

Fujii, Masashi; Awazu, Akinori; Nishimori, Hiraku

2010-07-01

The transition of a counter-chemotactic particle flow from a free-flow state to a jammed state in a quasi-one-dimensional path is investigated. One of the characteristic features of such a flow is that the constituent particles spontaneously form a cluster that blocks the path, called a path-blocking cluster (PBC), and causes a jammed state when the particle density is greater than a threshold value. Near the threshold value, the PBC occasionally collapses on itself to recover the free flow. In other words, the time evolution of the size of the PBC governs the flux of a counter-chemotactic flow. In this Rapid Communication, on the basis of numerical results of a stochastic cellular automata (SCA) model, we introduce a Langevin equation model for the size evolution of the PBC that reproduces the qualitative characteristics of the SCA model. The results suggest that the emergence of the jammed state in a quasi-one-dimensional counterflow is caused by a saddle-node bifurcation.

Osmotaxis in Escherichia coli through changes in motor speed

PubMed Central

Rosko, Jerko; Martinez, Vincent A.; Poon, Wilson C. K.

2017-01-01

Bacterial motility, and in particular repulsion or attraction toward specific chemicals, has been a subject of investigation for over 100 years, resulting in detailed understanding of bacterial chemotaxis and the corresponding sensory network in many bacterial species. For Escherichia coli most of the current understanding comes from the experiments with low levels of chemotactically active ligands. However, chemotactically inactive chemical species at concentrations found in the human gastrointestinal tract produce significant changes in E. coli’s osmotic pressure and have been shown to lead to taxis. To understand how these nonspecific physical signals influence motility, we look at the response of individual bacterial flagellar motors under stepwise changes in external osmolarity. We combine these measurements with a population swimming assay under the same conditions. Unlike for chemotactic response, a long-term increase in swimming/motor speeds is observed, and in the motor rotational bias, both of which scale with the osmotic shock magnitude. We discuss how the speed changes we observe can lead to steady-state bacterial accumulation. PMID:28874571

CP-10, a chemotactic peptide, is expressed in lesions of experimental autoimmune encephalomyelitis, neuritis, uveitis and in C6 gliomas.

PubMed

Deininger, M H; Zhao, Y; Schluesener, H J

1999-01-01

CP-10 (chemotactic protein of m.w. 10,000) is a member of the S100 superfamily of Ca2+ binding peptides, which has potent chemotactic activity for murine and human myeloid cells. Here we report on the generation of monoclonal antibodies against CP-10 and accumulation of CP-10+ cells during experimental autoimmune encephalomyelitis (EAE), neuritis (EAN), uveitis (EAU) and in experimentally transplanted C6 gliomas. During acute inflammation, CP-10 is mainly expressed by large ED1+ monocytic perivascular cells that accumulate at days 11-14. CP-10+ cells are predominantly located in areas of cellular infiltration but are as well found in the meninges and infiltrating the brain parenchyma. In transplanted gliomas, CP-10+ cells are located exclusively within the tumor parenchyma. Using double labeling experiments, other cells participating in the inflammatory reaction were found to express CP-10, like few lymphoblastic W3/13+ cells in the vicinity of the inflammatory infiltrate.

The Vi Capsular Polysaccharide Enables Salmonella enterica Serovar Typhi to Evade Microbe-Guided Neutrophil Chemotaxis

PubMed Central

Wangdi, Tamding; Lee, Cheng-Yuk; Spees, Alanna M.; Yu, Chenzhou; Kingsbury, Dawn D.; Winter, Sebastian E.; Hastey, Christine J.; Wilson, R. Paul

2014-01-01

Salmonella enterica serovar Typhi (S. Typhi) causes typhoid fever, a disseminated infection, while the closely related pathogen S. enterica serovar Typhimurium (S. Typhimurium) is associated with a localized gastroenteritis in humans. Here we investigated whether both pathogens differ in the chemotactic response they induce in neutrophils using a single-cell experimental approach. Surprisingly, neutrophils extended chemotactic pseudopodia toward Escherichia coli and S. Typhimurium, but not toward S. Typhi. Bacterial-guided chemotaxis was dependent on the presence of complement component 5a (C5a) and C5a receptor (C5aR). Deletion of S. Typhi capsule biosynthesis genes markedly enhanced the chemotactic response of neutrophils in vitro. Furthermore, deletion of capsule biosynthesis genes heightened the association of S. Typhi with neutrophils in vivo through a C5aR-dependent mechanism. Collectively, these data suggest that expression of the virulence-associated (Vi) capsular polysaccharide of S. Typhi obstructs bacterial-guided neutrophil chemotaxis. PMID:25101794

The HIV-1 gp41 ectodomain is cleaved by matriptase to produce a chemotactic peptide that acts through FPR2

PubMed Central

Wood, Matthew P; Cole, Amy L; Eade, Colleen R; Chen, Li-Mei; Chai, Karl X; Cole, Alexander M

2014-01-01

Several aspects of HIV-1 virulence and pathogenesis are mediated by the envelope protein gp41. Additionally, peptides derived from the gp41 ectodomain have been shown to induce chemotaxis in monocytes and neutrophils. Whereas this chemotactic activity has been reported, it is not known how these peptides could be produced under biological conditions. The heptad repeat 1 (HR1) region of gp41 is exposed to the extracellular environment and could therefore be susceptible to proteolytic processing into smaller peptides. Matriptase is a serine protease expressed at the surface of most epithelia, including the prostate and mucosal surfaces. Here, we present evidence that matriptase efficiently cleaves the HR1 portion of gp41 into a 22-residue chemotactic peptide MAT-1, the sequence of which is highly conserved across HIV-1 clades. We found that MAT-1 induced migration of primary neutrophils and monocytes, the latter of which act as a cellular reservoir of HIV during early stage infection. We then used formyl peptide receptor 1 (FPR1) and FPR2 inhibitors, along with HEK 293 cells, to demonstrate that MAT-1 can induce chemotaxis specifically using FPR2, a receptor found on the surface of monocytes, macrophages and neutrophils. These findings are the first to identify a proteolytic cleavage product of gp41 with chemotactic activity and highlight a potential role for matriptase in HIV-1 transmission and infection at epithelial surfaces and within tissue reservoirs of HIV-1. PMID:24617769

Pivotal Advance: Interconversion between pure chemotactic ligands and chemoattractant/secretagogue ligands of neutrophil C5a receptor by a single amino acid substitution.

PubMed

Jia, Nan; Semba, Umeko; Nishiura, Hiroshi; Kuniyasu, Akihiko; Nsiama, Tienabe K; Nishino, Norikazu; Yamamoto, Tetsuro

2010-06-01

Skp derived from Escherichia coli attracts leukocytes as a pure chemotactic ligand of the C5a receptor. We identified the submolecular region of Skp that binds and activates the C5a receptor to be -Gln103-Asp104-Arg105- using synthetic peptide fragments and site-directed mutants of Skp. As the C5a amino acid residue equivalent to Gln103 of Skp is Leu72, we prepared a Gln103Leu-Skp mutant as a recombinant protein. With this mutation, Skp gained secretagogue functions including induction of the respiratory burst and granule release reactions and leukotriene generation, in addition to the chemoattraction displayed by C5a. However, when we substituted Leu72 with Gln in C5a, the L72Q-C5a mutant largely lost its secretagogue function. These functional conversions were reproduced using synthetic peptides mimicking the receptor-binding/-activating regions of the recombinant proteins. Receptor-binding assays using the mimicking peptides demonstrated only a small difference between the Leu72-C5a and Gln72-C5a peptides. Consistently, L72Q-C5a apparently antagonized C5a secretagogue function. These results indicate that the difference between a chemotactic response and a combined chemotactic/secretory response can be attributed not to the nature of the receptor but to guidance by the ligand, at least in the case of C5a receptor-mediated leukocyte responses.

Leukotriene D4 induces chemotaxis in human eosinophilc cell line, EoL-1 cells via CysLT1 receptor activation.

PubMed

Shirasaki, Hideaki; Kanaizumi, Etsuko; Himi, Tetsuo

2017-11-01

Numerous reports have shown that cysteinyl leukotrienes (CysLTs) contribute to tissue accumulation of eosinophils in allergic airway inflammation. To date, only a few studies have reported that CysLTs promote chemotactic activity of human eosinophils in vitro. The purpose of this study was to investigate whether CysLTs promote chemotaxis in the human eosinophilic cell line, EoL-1. EoL-1 cells were induced to differentiate into mature eosinophil-like cells via incubation with butyric acid and cytokines (IL-3, IL-5 and GM-CSF). The chemotactic activity of the differentiated EoL-1 cells was assessed using the commercial cell migration assay kit. LTD 4 elicited dose-related chemotactic activity in the differntiated EoL-1 cells in the range of 1-100 nM. A typical bell-shaped dose-response curve was observed with optimal activity at 10 nM. The chemotactic activity elicited by LTD 4 (10 nM) was significantly inhibited by montelukast (control, 345 ± 19.2 × 10 3 RFU; LTD 4 10 nM alone, 511 ± 39.2 × 10 3 RFU; LTD 4 10 nM plus montelukast 100 nM, 387 ± 28.2 × 10 3 RFU). LTD 4 induces migration in eosinophilic cells via activation of CysLT1 receptor. The present in vitro model may be useful for elucidation of the mechanism underlying CysLT-induced tissue eosinophilia.

Amygdalin blocks the in vitro adhesion and invasion of renal cell carcinoma cells by an integrin-dependent mechanism.

PubMed

Juengel, Eva; Afschar, Masud; Makarević, Jasmina; Rutz, Jochen; Tsaur, Igor; Mani, Jens; Nelson, Karen; Haferkamp, Axel; Blaheta, Roman A

2016-03-01

Information about the natural compound amygdalin, which is employed as an antitumor agent, is sparse and thus its efficacy remains controversial. In this study, to determine whether amygdalin exerts antitumor effects on renal cell carcinoma (RCC) cells, its impact on RCC metastatic activity was investigated. The RCC cell lines, Caki-1, KTC-26 and A498, were exposed to amygdalin from apricot kernels, and adhesion to human vascular endothelium, immobilized collagen or fibronectin was investigated. The influence of amygdalin on chemotactic and invasive activity was also determined, as was the influence of amygdalin on surface and total cellular α and β integrin expression, which are involved in metastasis. We noted that amygdalin caused significant reductions in chemotactic activity, invasion and adhesion to endothelium, collagen and fibronectin. Using FACScan analysis, we noted that amygdalin also induced reductions, particularly in integrins α5 and α6, in all three cell lines. Functional blocking of α5 resulted in significantly diminished adhesion of KTC-26 and A498 to collagen and also in decreased chemotactic behavior in all three cell lines. Blocking α6 integrin significantly reduced chemotactic activity in all three cell lines. Thus, we suggest that exposing RCC cells to amygdalin inhibits metastatic spread and is associated with downregulation of α5 and α6 integrins. Therefore, we posit that amygdalin exerts antitumor activity in vitro, and this may be linked to integrin regulation.

Cysteinyl leukotrienes promote human airway smooth muscle migration.

PubMed

Parameswaran, Krishnan; Cox, Gerard; Radford, Katherine; Janssen, Luke J; Sehmi, Roma; O'Byrne, Paul M

2002-09-01

Cysteinyl leukotrienes promote airway smooth muscle (ASM) contraction and proliferation. Little is known about their role in ASM migration. We investigated this using cultured human ASMs (between the second and fifth passages) obtained from the large airways of resected nonasthmatic lung. Platelet-derived growth factor-BB (1 ng/ml) promoted significant (3.5-fold) ASM migration of myocytes across collagen-coated 8- micro m polycarbonate membranes in Transwell culture plates. Leukotriene E(4) (10(-7), 10(-8), 10(-9) M) did not demonstrate a chemotactic effect; it did promote chemokinesis. Priming by leukotriene E(4) (10(-7) M) significantly augmented the directional migratory response to platelet-derived growth factor (1.5-fold, p < 0.05). This was blocked by montelukast (10(-6) M), demonstrating the effect to be mediated by the cysteinyl leukotriene receptor. The "priming effect" was also partially attenuated by prostaglandin E(2) (10(-7) M). Whereas both the chemokinetic and the chemotactic "primed" responses were equally attenuated by a p38 mitogen-activated protein kinase inhibitor (SB203580, 25 micro M) and by a Rho-kinase inhibitor (Y27632, 10 micro M), the chemotactic response showed greater inhibition than chemokinesis by a phosphatidylinositol-3 kinase inhibitor (LY294002, 50 micro M). These experiments suggest that cysteinyl leukotrienes play an augmentary role in human ASM migration. The phosphatidylinositol-3 kinase pathway is a key signaling mechanism in the chemotactic migration of ASM cells in response to cysteinyl leukotrienes.

MULTISCALE MODELS OF TAXIS-DRIVEN PATTERNING IN BACTERIAL POPULATIONS

PubMed Central

XUE, CHUAN; OTHMER, HANS G.

2009-01-01

Spatially-distributed populations of various types of bacteria often display intricate spatial patterns that are thought to result from the cellular response to gradients of nutrients or other attractants. In the past decade a great deal has been learned about signal transduction, metabolism and movement in E. coli and other bacteria, but translating the individual-level behavior into population-level dynamics is still a challenging problem. However, this is a necessary step because it is computationally impractical to use a strictly cell-based model to understand patterning in growing populations, since the total number of cells may reach 1012 - 1014 in some experiments. In the past phenomenological equations such as the Patlak-Keller-Segel equations have been used in modeling the cell movement that is involved in the formation of such patterns, but the question remains as to how the microscopic behavior can be correctly described by a macroscopic equation. Significant progress has been made for bacterial species that employ a “run-and-tumble” strategy of movement, in that macroscopic equations based on simplified schemes for signal transduction and turning behavior have been derived [14, 15]. Here we extend previous work in a number of directions: (i) we allow for time-dependent signals, which extends the applicability of the equations to natural environments, (ii) we use a more general turning rate function that better describes the biological behavior, and (iii) we incorporate the effect of hydrodynamic forces that arise when cells swim in close proximity to a surface. We also develop a new approach to solving the moment equations derived from the transport equation that does not involve closure assumptions. Numerical examples show that the solution of the lowest-order macroscopic equation agrees well with the solution obtained from a Monte Carlo simulation of cell movement under a variety of temporal protocols for the signal. We also apply the method to derive equations of chemotactic movement that are governed by multiple chemotactic signals. PMID:19784399

Bifurcation in the chemotactic behavior of Physarum plasmodium

NASA Astrophysics Data System (ADS)

Shirakawa, Tomohiro; Gunji, Yukio-Pegio; Sato, Hiroshi; Tsubakino, Hiroto

2017-07-01

The plasmodium of true slime mold Physarum polycephalum is a unicellular and multinuclear giant amoeba. Since the cellular organism has some computational abilities, it is attracting much attention in the field of information science. However, previous studies have mainly focused on the optimization behavior of the plasmodium for a single-modality stimulus, and there are few studies on how the organism adapts to multi-modal stimuli. We stimulated the plasmodium with mixture of attractant and repellent stimuli, and we observed bifurcation in the chemotactic behavior of the plasmodium.

Collective Signal Processing in Cluster Chemotaxis: Roles of Adaptation, Amplification, and Co-attraction in Collective Guidance

PubMed Central

Camley, Brian A.; Zimmermann, Juliane; Levine, Herbert; Rappel, Wouter-Jan

2016-01-01

Single eukaryotic cells commonly sense and follow chemical gradients, performing chemotaxis. Recent experiments and theories, however, show that even when single cells do not chemotax, clusters of cells may, if their interactions are regulated by the chemoattractant. We study this general mechanism of “collective guidance” computationally with models that integrate stochastic dynamics for individual cells with biochemical reactions within the cells, and diffusion of chemical signals between the cells. We show that if clusters of cells use the well-known local excitation, global inhibition (LEGI) mechanism to sense chemoattractant gradients, the speed of the cell cluster becomes non-monotonic in the cluster’s size—clusters either larger or smaller than an optimal size will have lower speed. We argue that the cell cluster speed is a crucial readout of how the cluster processes chemotactic signals; both amplification and adaptation will alter the behavior of cluster speed as a function of size. We also show that, contrary to the assumptions of earlier theories, collective guidance does not require persistent cell-cell contacts and strong short range adhesion. If cell-cell adhesion is absent, and the cluster cohesion is instead provided by a co-attraction mechanism, e.g. chemotaxis toward a secreted molecule, collective guidance may still function. However, new behaviors, such as cluster rotation, may also appear in this case. Co-attraction and adaptation allow for collective guidance that is robust to varying chemoattractant concentrations while not requiring strong cell-cell adhesion. PMID:27367541

CD147 and CD98 complex-mediated homotypic aggregation attenuates the CypA-induced chemotactic effect on Jurkat T cells.

PubMed

Guo, Na; Zhang, Kui; Lv, Minghua; Miao, Jinlin; Chen, Zhinan; Zhu, Ping

2015-02-01

Homotypic cell aggregation plays important roles in physiological and pathological processes, including embryogenesis, immune responses, angiogenesis, tumor cell invasion and metastasis. CD147 has been implicated in most of these phenomena, and it was identified as a T cell activation-associated antigen due to its obvious up-regulation in activated T cells. However, the explicit function and mechanism of CD147 in T cells have not been fully elucidated. In this study, large and compact aggregates were observed in Jurkat T cells after treatment with the specific CD147 monoclonal antibody HAb18 or after the expression of CD147 was silenced by RNA interference, which indicated an inhibitory effect of CD147 in T cell homotypic aggregation. Knocking down CD147 expression resulted in a significant decrease in CD98, along with prominent cell aggregation, similar to that treated by CD98 and CD147 monoclonal antibodies. Furthermore, decreased cell chemotactic activity was observed following CD147- and CD98-mediated cell aggregation, and increased aggregation was correlated with a decrease in the chemotactic ability of the Jurkat T cells, suggesting that CD147- and CD98-mediated homotypic cell aggregation plays a negative role in T cell chemotaxis. Our data also showed that p-ERK, p-ZAP70, p-CD3ζ and p-LCK were significantly decreased in the CD147- and CD98-knocked down Jurkat T cells, which suggested that decreased CD147- and/or CD98-induced homotypic T cell aggregation and aggregation-inhibited chemotaxis might be associated with these signaling pathways. A role for CD147 in cell aggregation and chemotaxis was further indicated in primary CD4(+) T cells. Similarly, low expression of CD147 in primary T cells induced prominent cell aggregation and this aggregation attenuated primary T cell chemotactic ability in response to CypA. Our results have demonstrated the correlation between homotypic cell aggregation and the chemotactic response of T cells to CypA, and these data indicate that CD147 and CD98 might play important roles in cyclophilin-induced cell migration. Copyright © 2014 Elsevier Ltd. All rights reserved.

LEGO bricks used as chemotactic chambers: evaluation by a computer-assisted image analysis technique.

PubMed

Azzarà, A; Chimenti, M

2004-01-01

One of the main techniques used to explore neutrophil motility, employs micropore filters in chemotactic chambers. Many new models have been proposed, in order to perform multiple microassays in a rapid, inexpensive and reproducible way. In this work, LEGO bricks have been used as chemotactic chambers in the evaluation of neutrophil random motility and chemotaxis and compared with conventional Boyden chambers in a "time-response" experiment. Neutrophil motility throughout the filters was evaluated by means of an image-processing workstation, in which a dedicated algorithm recognizes and counts the cells in several fields and focal planes throughout the whole filter; correlates counts and depth values; performs a statistical analysis of data; calculates the true value of neutrophil migration; determines the distribution of cells; and displays the migration pattern. By this method, we found that the distances travelled by the cells in conventional chambers and in LEGO bricks were perfectly identical, both in random migration and under chemotactic conditions. Moreover, no interference with the physiological behaviour of neutrophils was detectable. In fact, the kinetics of migration was identical both in random migration (characterized by a gaussian pattern) and in chemotaxis (characterized by a typical stimulation peak, previously identified by our workstation). In conclusion, LEGO bricks are extremely precise devices. They are simple to use and allow the use of small amounts of chemoattractant solution and cell suspension, supplying by itself a triplicate test. LEGO bricks are inexpensive, fast and suitable for current diagnostic activity or for research investigations in every laboratory.

Calcitonin gene-related peptide (CGRP) activates human neutrophils--inhibition by chemotactic peptide antagonist BOC-MLP.

PubMed Central

Richter, J; Andersson, R; Edvinsson, L; Gullberg, U

1992-01-01

The effect of the neuropeptides substance P, neurokinin A and alpha-calcitonin gene-related peptide (CGRP) on human neutrophil granulocytes was investigated. Substance P induced secondary granule secretion at a concentration of 100 microM. CGRP induced a significant secretory response at 10 microM and thus appeared to be about 10 times more potent than substance P. Calcitonin and a fragment of CGRP, CGRP(8-37), had no effect on neutrophil degranulation. The chemotactic peptide antagonist BOC-MLP (100 microM) inhibited lactoferrin secretion mediated both by CGRP and chemotactic peptide FMLP almost completely, while secretion in response to tumour necrosis factor (TNF) was unaffected. Results from receptor binding studies showed that CGRP and N-formyl-methionyl-leucyl-phenylalanine (FMLP) do not compete for binding. This indicates that CGRP does not exert its effects by binding to the chemotactic peptide receptor. CGRP induced a rapid increase in the cytosolic-free calcium concentration and this increase was not, unlike that induced by FMLP, abolished by preincubation of the cells with pertussis toxin (1000 ng/ml). Therefore CGRP signal transduction in neutrophils appears to involve rapid changes in the cytosolic-free calcium concentration but not a pertussis toxin-sensitive G-protein. In summary, this is the first report to show that CGRP can directly activate neutrophil granulocytes, and this probably occurs via a cell surface receptor which is distinct from that of FMLP although both the CGRP and FMLP-mediated effects can be blocked by BOC-MLP. Images Figure 3 PMID:1282494

A chemotactic signaling surface on CheY defined by suppressors of flagellar switch mutations.

PubMed Central

Roman, S J; Meyers, M; Volz, K; Matsumura, P

1992-01-01

CheY is the response regulator protein that interacts with the flagellar switch apparatus to modulate flagellar rotation during chemotactic signaling. CheY can be phosphorylated and dephosphorylated in vitro, and evidence indicates that CheY-P is the activated form that induces clockwise flagellar rotation, resulting in a tumble in the cell's swimming pattern. The flagellar switch apparatus is a complex macromolecular structure composed of at least three gene products, FliG, FliM, and FliN. Genetic analysis of Escherichia coli has identified fliG and fliM as genes in which mutations occur that allele specifically suppress cheY mutations, indicating interactions among these gene products. We have generated a class of cheY mutations selected for dominant suppression of fliG mutations. Interestingly, these cheY mutations dominantly suppressed both fliG and fliM mutations; this is consistent with the idea that the CheY protein interacts with both switch gene products during signaling. Biochemical characterization of wild-type and suppressor CheY proteins did not reveal altered phosphorylation properties or evidence for phosphorylation-dependent CheY multimerization. These data indicate that suppressor CheY proteins are specifically altered in the ability to transduce chemotactic signals to the switch at some point subsequent to phosphorylation. Physical mapping of suppressor amino acid substitutions on the crystal structure of CheY revealed a high degree of spatial clustering, suggesting that this region of CheY is a signaling surface that transduces chemotactic signals to the switch. Images PMID:1400175

Feeding ducks, bacterial chemotaxis, and the Gini index

NASA Astrophysics Data System (ADS)

Peaudecerf, François J.; Goldstein, Raymond E.

2015-08-01

Classic experiments on the distribution of ducks around separated food sources found consistency with the "ideal free" distribution in which the local population is proportional to the local supply rate. Motivated by this experiment and others, we examine the analogous problem in the microbial world: the distribution of chemotactic bacteria around multiple nearby food sources. In contrast to the optimization of uptake rate that may hold at the level of a single cell in a spatially varying nutrient field, nutrient consumption by a population of chemotactic cells will modify the nutrient field, and the uptake rate will generally vary throughout the population. Through a simple model we study the distribution of resource uptake in the presence of chemotaxis, consumption, and diffusion of both bacteria and nutrients. Borrowing from the field of theoretical economics, we explore how the Gini index can be used as a means to quantify the inequalities of uptake. The redistributive effect of chemotaxis can lead to a phenomenon we term "chemotactic levelling," and the influence of these results on population fitness are briefly considered.

Chemotaxing and haptotaxing random walkers having directional persistence

NASA Astrophysics Data System (ADS)

Kwon, Tae Goo; Kyoungjin Lee Team; Taeseok Daniel Yang Team

2015-03-01

Biological cell crawling is a rather complex process involving various bio-chemical and bio-mechanical processes, many of which are still not well understood. The difficulties in understanding the crawling are originating not just from cell-intrinsic factors but from their complex social interactions, cell-to-substrate interactions and nonlinear responses toward extrinsic factors. Here, in this report we investigate chemotactic behavior of mathematical model cells that naturally have directional persistence. A cell density is measured as a function of time and space, then the resulting steady state is compared with that of the well-known Keller-Segal model, which describes a population of chemotactic random walker. Then, we add a cell-to-cell interaction, mimicking a ``haptotaxis'' mediated interaction, to the model and access its role as for altering the steady-state cell density profile. This mathematical model system, which we have developed and considered in this work, can be quite relevant to the chemotactic responses of interacting immune cells, like microglia, moving toward and around a site of wound, as for an example. We conclude by discussing some relevant recent experimental findings.

Streptolysin O Inhibition of Neutrophil Chemotaxis and Mobility: Nonimmune Phenomenon with Species Specificity

PubMed Central

Van Epps, Dennis E.; Andersen, Burton R.

1974-01-01

The effects of streptolysin O (SO) (1 to 4 hemolytic units) on the mobility of neutrophilic leukocytes from humans, baboons, sheep, and rabbits were compared. After SO treatment, chemotaxis and random mobility of human neutrophils were markedly suppressed, baboon and sheep neutrophils were partially suppressed, and rabbit neutrophils were unaffected and demonstrated normal chemotaxis and mobility. The amounts of SO used in the mobility studies caused no leukocyte lysis or trypan blue uptake by human, baboon, or sheep cells, and minimal lysis or trypan blue uptake by rabbit cells. The possible involvement of immune mediators in the observed inhibition of human neutrophils was considered and excluded by the following studies. White blood cells from humans with humoral or cellular immune deficiencies responded in a manner similar to normal human cells; supernatant solutions from SO-treated human white blood cells did not contain a chemotactic suppressor; preincubation of SO with cholesterol (an inhibitor of SO hemolytic activity) caused loss of the chemotactic suppressive effect of the toxin on human leukocytes; and leukocytes from rabbits preimmunized with SO remained refractory to chemotactic suppression. Images PMID:4128632

Multiscale Characterization of Bacterial Swarming Illuminates Principles Governing Directed Surface Motility

NASA Astrophysics Data System (ADS)

Strickland, Ben; Hoeger, Kentaro; Ursell, Tristan

In many systems, individual characteristics interact, leading to the spontaneous emergence of order and complexity. In biological settings like microbes, such collective behaviors can imbue a variety of benefits to constituent individuals, including increased spatial range, improved access to nutrients, and enhanced resistance to antibiotic threats. To untangle the biophysical underpinnings of collective motility, we use passive tracers and a curated genetic library of Bacillus subtilis, including motile, non-motile, biofilm-deficient, and non-chemotactic mutants. We characterize and connect individual behavior on the microscopic scale to macroscopic colony morphology and motility of dendritic swarming. We analyze the persistence and dynamics of coordinated movement on length scales up to 4 orders of magnitude larger than that of individual cells, revealing rapid and directed responses of microbial groups to external stimuli, such as avoidance dynamics across chemical gradients. Our observations uncover the biophysical interplay between individual motility, surface wetness, phenotypic diversity, and external physical forces that robustly precipitate coordinated group behavior in microbes, and suggest general principles that govern the transition from individual to group behavior.

Human type II pneumocyte chemotactic responses to CXCR3 activation are mediated by splice variant A.

PubMed

Ji, Rong; Lee, Clement M; Gonzales, Linda W; Yang, Yi; Aksoy, Mark O; Wang, Ping; Brailoiu, Eugen; Dun, Nae; Hurford, Matthew T; Kelsen, Steven G

2008-06-01

Chemokine receptors control several fundamental cellular processes in both hematopoietic and structural cells, including directed cell movement, i.e., chemotaxis, cell differentiation, and proliferation. We have previously demonstrated that CXCR3, the chemokine receptor expressed by Th1/Tc1 inflammatory cells present in the lung, is also expressed by human airway epithelial cells. In airway epithelial cells, activation of CXCR3 induces airway epithelial cell movement and proliferation, processes that underlie lung repair. The present study examined the expression and function of CXCR3 in human alveolar type II pneumocytes, whose destruction causes emphysema. CXCR3 was present in human fetal and adult type II pneumocytes as assessed by immunocytochemistry, immunohistochemistry, and Western blotting. CXCR3-A and -B splice variant mRNA was present constitutively in cultured type II cells, but levels of CXCR3-B greatly exceeded CXCR3-A mRNA. In cultured type II cells, I-TAC, IP-10, and Mig induced chemotaxis. Overexpression of CXCR3-A in the A549 pneumocyte cell line produced robust chemotactic responses to I-TAC and IP-10. In contrast, I-TAC did not induce chemotactic responses in CXCR3-B and mock-transfected cells. Finally, I-TAC increased cytosolic Ca(2+) and activated the extracellular signal-regulated kinase, p38, and phosphatidylinositol 3-kinase (PI 3-kinase)/protein kinase B kinases only in CXCR3-A-transfected cells. These data indicate that the CXCR3 receptor is expressed by human type II pneumocytes, and the CXCR3-A splice variant mediates chemotactic responses possibly through Ca(2+) activation of both mitogen-activated protein kinase and PI 3-kinase signaling pathways. Expression of CXCR3 in alveolar epithelial cells may be important in pneumocyte repair from injury.

Induction of Macrophage Chemotaxis by Aortic Extracts from Patients with Marfan Syndrome Is Related to Elastin Binding Protein

PubMed Central

Guo, Gao; Gehle, Petra; Doelken, Sandra; Martin-Ventura, José Luis; von Kodolitsch, Yskert; Hetzer, Roland; Robinson, Peter N.

2011-01-01

Marfan syndrome is an autosomal dominantly inherited disorder of connective tissue with prominent skeletal, ocular, and cardiovascular manifestations. Aortic aneurysm and dissection are the major determinants of premature death in untreated patients. In previous work, we showed that extracts of aortic tissues from the mgR mouse model of Marfan syndrome showed increased chemotactic stimulatory activity related to the elastin-binding protein. Aortic samples were collected from 6 patients with Marfan syndrome and 8 with isolated aneurysms of the ascending aorta. Control samples were obtained from 11 organ donors without known vascular or connective tissue diseases. Soluble proteins extracted from the aortic samples of the two patient groups were compared against buffer controls and against the aortic samples from controls with respect to the ability to induce macrophage chemotaxis as measured using a modified Boyden chamber, as well as the reactivity to a monoclonal antibody BA4 against bioactive elastin peptides using ELISA. Samples from Marfan patients displayed a statistically significant increase in chemotactic inductive activity compared to control samples. Additionally, reactivity to BA4 was significantly increased. Similar statistically significant increases were identified for the samples from patients with idiopathic thoracic aortic aneurysm. There was a significant correlation between the chemotactic index and BA4 reactivity, and the increases in chemotactic activity of extracts from Marfan patients could be inhibited by pretreatment with lactose, VGVAPG peptides, or BA4, which indicates the involvement of EBP in mediating the effects. Our results demonstrate that aortic extracts of patients with Marfan syndrome can elicit macrophage chemotaxis, similar to our previous study on aortic extracts of the mgR mouse model of Marfan syndrome (Guo et al., Circulation 2006; 114:1855-62). PMID:21647416

Neural differentiation of mesenchymal stem cells influences chemotactic responses to HGF.

PubMed

Zheng, Bing; Wang, Chunyan; He, Lihong; Xu, Xiaojing; Qu, Jing; Hu, Jun; Zhang, Huanxiang

2013-01-01

Recently, mesenchymal stem cells (MSCs) have been extensively used for cell-based therapies in neuronal degenerative disease. Although much effort has been devoted to the delineation of factors involved in the migration of MSCs, the relationship between the chemotactic responses and the differentiation status of these cells remains elusive. Here, we report that MSCs in varying neural differentiation states display different chemotactic responses to hepatocyte growth factor (HGF): first, the number of chemotaxing MSCs and the optimal concentrations of HGF that induced the peak migration varied greatly; second, time-lapse video analysis showed that MSCs in certain differentiation state migrated more efficiently toward HGF; third, the phosphorylation levels of Akt, ERK1/2, SAPK/JNK, and p38MAPK were closely related to the differentiation levels of MSCs subjected to HGF; and finally, although inhibition of ERK1/2 signaling significantly attenuated HGF-stimulated transfilter migration of both undifferentiated and differentiating MSCs, abolishment of PI3K/Akt, p38MAPK, or SAPK/JNK signaling only decreased the number of migrated cells in certain differentiation state(s). Blocking of PI3K/Akt or MAPK signaling impaired the migration efficiency and/or speed, the extent of which depends on the cell differentiation states. Meanwhile, F-actin rearrangement, which is essential for MSCs chemotaxis, was induced by HGF, and the time points of cytoskeletal reorganization were different among these cells. Collectively, these results demonstrate that neural differentiation of MSCs influences their chemotactic responses to HGF: MSCs in varying differentiation states possess different migratory capacities, thereby shedding light on optimization of the therapeutic potential of MSCs to be employed for neural regeneration after injury. Copyright © 2012 Wiley Periodicals, Inc.

Enhanced basophil histamine release and neutrophil chemotactic activity predispose grain dust-induced airway obstruction.

PubMed

Park, H; Jung, K; Kang, K; Nahm, D; Cho, S; Kim, Y

1999-04-01

The pathogenic mechanism of grain dust (GD)-induced occupational asthma (OA) remains unclear. To understand further the mechanism of GD-induced OA. Fifteen employees working in a same GD industry, complaining of work-related respiratory symptoms, were enrolled and were divided into two groups according to the GD-bronchoprovocation test (BPT) result: six positive responders were grouped as group III, nine negative responders as group II and five healthy controls as group I. Serum GD-specific immunoglobulin (Ig)E (sIgE), specific IgG (sIgG) and specific IgG4 (sIgG4) antibodies were detected by enzyme-linked immunosorbent assay. Basophil histamine release was measured by the autofluorometric method, and changes of serum neutrophil chemotactic activity were observed by the Boyden chamber method. For clinical parameters such as degree of airway hyperresponsiveness to methacholine, duration of respiratory symptoms, exposure duration, and prevalences of serum sIgE, sIgG and sIgG4 antibodies, there were no significant differences between group II and III (P > 0.05, respectively). Serum neutrophil chemotactic activity increased significantly at 30 min and decreased at 240 min after the GD-BPT in group III subjects (P < 0.05, respectively), while no significant changes were noted in group II subjects (P > 0.05). Basophil histamine release induced by GD was significantly higher in group III than those of group I or group II (P < 0.05, respectively), while minimal release of anti-IgG4 antibodies was noted in all three groups. These results suggest that enhanced basophil histamine release and serum neutrophil chemotactic activity might contribute to the development of GD-induced occupational asthma.

Defective neutrophil chemotaxis in juvenile periodontitis.

PubMed Central

Clark, R A; Page, R C; Wilde, G

1977-01-01

Neutrophil chemotaxis was evaluated in nine patients with juvenile periodontitis, with normal subjects and patients with the adult form of periodontitis as controls. Defective chemotactic responses were observed in neutrophils from seven of nine juvenile patients, and a reduced level of complement-derived chemotactic activity was demonstrated in serum from four patients. These determinations were normal in all the patients with adult periodontitis. Serum from five of the juvenile patients contained a heat-stable, non-dialyzable factor that markedly inhibited the chemotaxis of normal neutrophils. Thus the characteristic tissue destruction seen in juvenile periodontitis may be, at least in part, a consequence of a failure of host defense mechanisms. PMID:591063

In vitro inhibitory effects of Moringa oleifera leaf extract and its major components on chemiluminescence and chemotactic activity of phagocytes.

PubMed

Vongsak, Boonyadist; Gritsanapan, Wandee; Wongkrajang, Yuvadee; Jantan, Ibrahim

2013-11-01

The ethanol extract of Moringa oleifera Lam. leaves and its major constituents, crypto-chlorogenic acid, quercetin 3-O-glucoside and kaempferol 3-O-glucoside, were investigated on the respiratory burst of human whole blood and isolated human polymorphonuclear leukocytes (PMNs) using a luminol-based chemiluminescence assay. The chemotactic migration of PMNs was also investigated using the Boyden chamber technique. The ethanol extract demonstrated inhibitory activities on the oxidative burst and the chemotactic migration of PMNs. Quercetin 3-O-glucoside, crypto-chlorogenic acid, and kaempferol 3-O-glucoside, isolated from the extract, expressed relatively strong inhibitory activity on the oxidative burst of PMNs with IC50 values of 4.1, 6.7 and 7.0 microM, respectively, comparable with that of aspirin. They also demonstrated strong inhibition of chemotatic migration of PMNs with IC50 values of 9.5, 15.9 and 18.2 microM, respectively. The results suggest that M. oleifera leaves could modulate the immune response of human phagocytes, linking to its ethnopharmacological use as an anti-inflammatory agent. The immunomodulating activity of the plant was mainly due to its major components.

A Plasma Protein Indistinguishable from Ribosomal Protein S19

PubMed Central

Semba, Umeko; Chen, Jun; Ota, Yoshihiko; Jia, Nan; Arima, Hidetoshi; Nishiura, Hiroshi; Yamamoto, Tetsuro

2010-01-01

A monocyte-chemoattracting factor is generated during blood coagulation and during clotting of platelet-rich plasma. This chemotactic factor attracts monocytes as a ligand of the C5a receptor; however, it inhibits C5a-induced neutrophil chemotaxis as an apparent receptor antagonist. The curious dual function of the serum monocyte chemotactic factor resembles that of the cross-linked homodimer of ribosomal protein S19 (RP S19). Indeed, the inactive precursor of the monocyte chemotactic factor was present in plasma, and the precursor molecule and RP S19, as well as the active form and the RP S19 dimer, were indistinguishable in terms of immunological reactivity and molecular size. Coagulation factor XIIIa, plasma transglutaminase, and membrane phosphatidylserine on the activated platelets were required for conversion of the precursor to the active form. In addition, the precursor molecule in plasma could be replaced by wild-type recombinant RP S19 but not by mutant forms of it. These results indicate that a molecule indistinguishable from RP S19 was present in plasma, and that the RP S19-like molecule was converted to the active form by a transglutaminase-catalyzed reaction on a scaffold that included the phosphatidylserine-exposed platelet membrane. PMID:20093496

Nucleotides induce chemotaxis and actin polymerization in immature but not mature human dendritic cells via activation of pertussis toxin-sensitive P2y receptors.

PubMed

Idzko, Marco; Dichmann, Stefan; Ferrari, Davide; Di Virgilio, Francesco; la Sala, Andrea; Girolomoni, Giampiero; Panther, Elisabeth; Norgauer, Johannes

2002-08-01

Dendritic cells (DCs) are considered the principal initiators of immune response because of their ability to migrate into peripheral tissues and lymphoid organs, process antigens, and activate naive T cells. There is evidence that extracellular nucleotides regulate certain functions of DCs via G-protein-coupled P2Y receptors (P2YR) and ion-channel-gated P2X receptors (P2XR). Here we investigated the chemotactic activity and analyzed the migration-associated intracellular signaling events such as actin reorganization and Ca(++) transients induced by common P2R agonists such as adenosine 5'-triphosphate (ATP) and 2-methylthioadenosine triphosphate, the P2YR agonists UTP and adenosine 5'-diphosphate (ADP), or the P2XR agonists alphabeta-methylenadenosine-5'-triphosphate and 2',3'-(4-benzoyl)benzoyl-ATP. The common P2R agonists and the selective P2YR agonists turned out to be potent chemotactic stimuli for immature DCs, but not for mature DCs. In contrast, P2XR agonists had only marginal chemotactic activity in both DC types. Chemotaxis was paralleled by a rise in the intracellular Ca(++) concentration and by actin polymerization. Studies with pertussis toxin implicated that intracellular signaling events such as actin polymerization, mobilization of intracellular Ca(++), and migration induced by nucleotides was mediated via G(i/o) protein-coupled P2YR. Moreover, functional studies revealed selective down-regulation of this G(i/o) protein-coupled chemotactic P2YR responsiveness during maturation, although immature and mature DCs expressed similar amounts of mRNA for the P2R subtypes (P2Y(2)R, P2Y(4)R, P2Y(5)R, P2Y(7)R, P2Y(11)R and P2X(1)R, P2X(4)R, P2X(7)R), and no major differences in respect to the mRNA expression of these receptors could be observed by semiquantitative reverse transcription and polymerase chain reaction (RT-PCR). In summary, our data describe a differential chemotactic response of immature and mature DCs to nucleotides, and lend further support to the hypothesis that P2R are a novel class of immunomodulatory plasma membrane receptors suitable for pharmacological intervention.

In vivo activation of equine eosinophils and neutrophils by experimental Strongylus vulgaris infections.

PubMed

Dennis, V A; Klei, T R; Chapman, M R; Jeffers, G W

1988-12-01

Eosinophils and neutrophils from ponies with Strongylus vulgaris-induced eosinophilia (eosinophilic ponies; activated eosinophils and neutrophils) were assayed in vitro for chemotactic and chemokinetic responses to zymosan-activated serum (ZAS) using the filter system in Boyden chambers, for Fc and complement (C) receptors using the EA and EAC-rosette assays, respectively, and for phagocytic and bactericidal activities using opsonized Escherichia coli and the acridine orange method. The responses of activated eosinophils and neutrophils in the above assays were compared with those of eosinophils and neutrophils from S. vulgaris-naive ponies without eosinophilia (noneosinophilic ponies; nonactivated eosinophils and neutrophils). Differences in cell density following centrifugation in a continuous Percoll gradient were used to further characterize the heterogeneity of activated eosinophils and neutrophils. Activated and nonactivated eosinophils demonstrated similar chemotactic responses to ZAS while activated and nonactivated neutrophils demonstrated similar chemokinetic responses to ZAS. A higher percentage of activated eosinophils and neutrophils expressed Fc and C receptors compared with nonactivated cells (P less than 0.05). Generally, higher percentages of eosinophils and neutrophils expressed C than Fc receptors. However, the percentage of neutrophils with both receptors was higher than that of eosinophils. Phagocytosis and killing of E. coli by either type of eosinophil were not consistently observed. Both activated and nonactivated neutrophils phagocytized E. coli and significant differences between the two cell types were not observed. The bacterial activity, however, of activated neutrophils was significantly greater than that obtained using nonactivated neutrophils (P less than 0.05). Activated eosinophils and neutrophils were both separated into two distinct fractions based on differences in cell densities. A higher percentage of band 2 eosinophils (density of 1.106) expressed C receptors than did band 1 eosinophils (density of 1.049) (P less than 0.05). A higher percentage of band 1 neutrophils (density of 1.072) expressed both Fc and C receptors and these neutrophils were more phagocytic and bactericidal than were band 2 neutrophils (density of 1.082) (P less than 0.05). These data suggest that equine eosinophils and neutrophils are activated by chronic S. vulgaris infections.

Chemotactic-based adaptive self-organization during colonial development

NASA Astrophysics Data System (ADS)

Cohen, Inon; Czirók, Andras; Ben-Jacob, Eshel

1996-02-01

Bacterial colonies have developed sophisticated modes of cooperative behavior which enable them to respond to adverse growth conditions. It has been shown that such behavior can be manifested in the development of complex colonial patterns. Certain bacterial species exhibit formation of branching patterns during colony development. Here we present a generic model to describe such patterning of swimming (tumbling) bacteria on agar surfaces. The model incorporates: (1) food diffusion, (2) reproduction and sporulation of the cells, (3) movement of the bacterial cells within a self-produced wetting fluid and (4) chemotactic signaling. As a plausible explanation for transitions between different branching morphologies, we propose an interplay between chemotaxis towards food, self-produced short range chemoattractant and long range chemorepellent.

Multi-phasic bi-directional chemotactic responses of the growth cone

PubMed Central

Naoki, Honda; Nishiyama, Makoto; Togashi, Kazunobu; Igarashi, Yasunobu; Hong, Kyonsoo; Ishii, Shin

2016-01-01

The nerve growth cone is bi-directionally attracted and repelled by the same cue molecules depending on the situations, while other non-neural chemotactic cells usually show uni-directional attraction or repulsion toward their specific cue molecules. However, how the growth cone differs from other non-neural cells remains unclear. Toward this question, we developed a theory for describing chemotactic response based on a mathematical model of intracellular signaling of activator and inhibitor. Our theory was first able to clarify the conditions of attraction and repulsion, which are determined by balance between activator and inhibitor, and the conditions of uni- and bi-directional responses, which are determined by dose-response profiles of activator and inhibitor to the guidance cue. With biologically realistic sigmoidal dose-responses, our model predicted tri-phasic turning response depending on intracellular Ca2+ level, which was then experimentally confirmed by growth cone turning assays and Ca2+ imaging. Furthermore, we took a reverse-engineering analysis to identify balanced regulation between CaMKII (activator) and PP1 (inhibitor) and then the model performance was validated by reproducing turning assays with inhibitions of CaMKII and PP1. Thus, our study implies that the balance between activator and inhibitor underlies the multi-phasic bi-directional turning response of the growth cone. PMID:27808115

Protein malnutrition promotes dysregulation of molecules involved in T cell migration in the thymus of mice infected with Leishmania infantum

PubMed Central

Losada-Barragán, Monica; Umaña-Pérez, Adriana; Cuervo-Escobar, Sergio; Berbert, Luiz Ricardo; Porrozzi, Renato; Morgado, Fernanda N.; Mendes-da-Cruz, Daniella Areas; Savino, Wilson; Sánchez-Gómez, Myriam; Cuervo, Patricia

2017-01-01

Protein malnutrition, the most deleterious cause of malnutrition in developing countries, has been considered a primary risk factor for the development of clinical visceral leishmaniasis (VL). Protein malnutrition and infection with Leishmania infantum leads to lymphoid tissue disorganization, including changes in cellularity and lymphocyte subpopulations in the thymus and spleen. Here we report that protein malnutrition modifies thymic chemotactic factors by diminishing the CCL5, CXCL12, IGF1, CXCL9 and CXCL10 protein levels in infected animals. Nevertheless, T cells preserve their migratory capability, as they were able to migrate ex vivo in response to chemotactic stimuli, indicating that malnutrition may compromise the thymic microenvironment and alter in vivo thymocyte migration. Decrease in chemotactic factors protein levels was accompanied by an early increase in the parasite load of the spleen. These results suggest that the precondition of malnutrition is affecting the cell-mediated immune response to L. infantum by altering T cell migration and interfering with the capacity of protein-deprived animals to control parasite spreading and proliferation. Our data provide evidence for a disturbance of T lymphocyte migration involving both central and peripheral T-cells, which likely contribute to the pathophysiology of VL that occurs in malnourished individuals. PMID:28397794

Chemotaxis Increases the Residence Time Distribution of Bacteria in Granular Media Containing Distributed Contaminant Sources

NASA Astrophysics Data System (ADS)

Adadevoh, J.; Triolo, S.; Ramsburg, C. A.; Ford, R.

2015-12-01

The use of chemotactic bacteria in bioremediation has the potential to increase access to, and biotransformation of, contaminant mass within the subsurface environment. This laboratory-scale study aimed to understand and quantify the influence of chemotaxis on residence times of pollutant-degrading bacteria within homogeneous treatment zones. Focus was placed on a continuous flow sand-packed column system in which a uniform distribution of naphthalene crystals created distributed sources of dissolved phase contaminant. A 10 mL pulse of Pseudomonas putida G7, which is chemotactic to naphthalene, and Pseudomonas putida G7 Y1, a non-chemotactic mutant strain, were simultaneously introduced into the sand-packed column at equal concentrations. Breakthrough curves obtained for the bacteria from column experiments conducted with and without naphthalene were used to quantify the effect of chemotaxis on transport parameters. In the presence of the chemoattractant, longitudinal dispersivity of PpG7 increased by a factor of 3 and percent recovery decreased from 21% to 12%. The results imply that pore-scale chemotaxis responses are evident at an interstitial fluid velocity of 1.7 m/d, which is within the range of typical groundwater flow. Within the context of bioremediation, chemotaxis may work to enhance bacterial residence times in zones of contamination thereby improving treatment.

Identification of CtpL as a chromosomally encoded chemoreceptor for 4-chloroaniline and catechol in Pseudomonas aeruginosa PAO1.

PubMed

Vangnai, Alisa S; Takeuchi, Kazuki; Oku, Shota; Kataoka, Naoya; Nitisakulkan, Tisana; Tajima, Takahisa; Kato, Junichi

2013-12-01

Bacterial chemotaxis influences the ability of bacteria to survive and thrive in most environments, including polluted ones. Despite numerous reports of the phenotypic characterization of chemotactic bacteria, only a few molecular details of chemoreceptors for aromatic pollutants have been described. In this study, the molecular basis of chemotaxis toward an environmentally toxic chlorinated aromatic pollutant, 4-chloroaniline (4CA), was evaluated. Among the three Pseudomonas spp. tested, Pseudomonas aeruginosa PAO1 exhibited positive chemotaxis both to the nonmetabolizable 4CA, where 4-chloroacetanilide was formed as a dead-end transformation product, and to the metabolizable catechol. Molecular analysis of all 26 mutants with a disrupted methyl-accepting chemotaxis gene revealed that CtpL, a chromosomally encoded chemoreceptor, was responsible for the positive chemotactic response toward 4CA. Since CtpL has previously been described to be a major chemoreceptor for inorganic phosphate at low concentrations in PAO1, this report describes a fortuitous ability of CtpL to function toward aromatic pollutants. In addition, its regulation not only was dependent on the presence of the chemoattractant inducer but also was regulated by conditions of phosphate starvation. These results expand the range of known chemotactic transducers and their function in the environmental bacterium PAO1.

MicroRNA-124 Controls the Proliferative, Migratory, and Inflammatory Phenotype of Pulmonary Vascular Fibroblasts

PubMed Central

Wang, Daren; Zhang, Zhang; Li, Min; Frid, Maria G.; Flockton, Amanda R.; McKeon, B. Alexandre; Yeager, Michael E.; Fini, Mehdi A.; Morrell, Nicholas W.; Pullamsetti, Soni S.; Velegala, Sivareddy; Seeger, Werner; McKinsey, Timothy A.; Sucharov, Carmen C.; Stenmark, Kurt R.

2014-01-01

Rationale Pulmonary hypertensive remodeling is characterized by excessive proliferation, migration, and proinflammatory activation of adventitial fibroblasts. In culture, fibroblasts maintain a similar activated phenotype. The mechanisms responsible for generation/maintenance of this phenotype remain unknown. Objective We hypothesized that aberrant expression of microRNA-124 (miR-124) regulates this activated fibroblast phenotype and sought to determine the signaling pathways through which miR-124 exerts effects. Methods and Results We detected significant decreases in miR-124 expression in fibroblasts isolated from calves and humans with severe pulmonary hypertension. Overexpression of miR-124 by mimic transfection significantly attenuated proliferation, migration, and monocyte chemotactic protein-1 expression of hypertensive fibroblasts, whereas anti–miR-124 treatment of control fibroblasts resulted in their increased proliferation, migration, and monocyte chemotactic protein-1 expression. Furthermore, the alternative splicing factor, polypyrimidine tract–binding protein 1, was shown to be a direct target of miR-124 and to be upregulated both in vivo and in vitro in bovine and human pulmonary hypertensive fibroblasts. The effects of miR-124 on fibroblast proliferation were mediated via direct binding to the 3′ untranslated region of polypyrimidine tract–binding protein 1 and subsequent regulation of Notch1/phosphatase and tensin homolog/FOXO3/p21Cip1 and p27Kip1 signaling. We showed that miR-124 directly regulates monocyte chemotactic protein-1 expression in pulmonary hypertension/idiopathic pulmonary arterial hypertension fibroblasts. Furthermore, we demonstrated that miR-124 expression is suppressed by histone deacetylases and that treatment of hypertensive fibroblasts with histone deacetylase inhibitors increased miR-124 expression and decreased proliferation and monocyte chemotactic protein-1 production. Conclusions Stable decreases in miR-124 expression contribute to an epigenetically reprogrammed, highly proliferative, migratory, and inflammatory phenotype of hypertensive pulmonary adventitial fibroblasts. Thus, therapies directed at restoring miR-124 function, including histone deacetylase inhibitors, should be investigated. PMID:24122720

Grain dust induces IL-8 production from bronchial epithelial cells: effect on neutrophil recruitment.

PubMed

Park, H S; Suh, J H; Kim, S S; Kwon, O J

2000-06-01

There have been several investigations suggesting an involvement of activated neutrophils in the development of grain dust (GD)-induced occupational asthma. Interleukin-8 in the sputa from GD-induced asthmatic patients increased significantly after the exposure to GD. To confirm IL-8 production from bronchial epithelial cells when exposed to GD, and to evaluate the role of IL-8 on neutrophil recruitment. We cultured Beas-2B, a bronchial epithelial cell line. To observe GD-induced responses, four different concentrations ranging from 1 to 200 microg/mL of GD were incubated for 24 hours and compared with those without incubation of GD. To evaluate the effect of pro-inflammatory cytokines on IL-8 production and neutrophil chemotaxis, epithelial cells were incubated with peripheral blood mononuclear cell (PBMC) culture supernatant derived from subjects with GD-induced asthma exposed to 10 microg/mL of GD, and then compared with those without addition of PBMC supernatant. The level of released IL-8 in the supernatant was measured by enzyme-linked immunosorbent assay. Neutrophil chemotactic activity of the culture supernatant was determined by modified Boyden chamber method. Interleukin-8 production and neutrophil chemotactic activity from bronchial epithelial cells significantly increased with additions of GD in a dose-dependent manner (P < .05, respectively), and were significantly augmented with additions of PBMC supernatant (P < .05, respectively) at each concentration. Close correlation was noted between neutrophil chemotactic activity and IL-8 level (r = 0.87, P < .05). Compared with the untreated sample, pre-treatment of anti-IL-8 antibody induced a significant suppression (up to 67.2%) of neutrophil chemotactic activity in a dose-dependent manner. These results suggest that IL-8 produced from bronchial epithelial cells may be a major cytokine, which induces neutrophil migration into the airways when exposed to GD.

Regulation of Pseudomonas aeruginosa chemotaxis by the nitrogen source.

PubMed Central

Craven, R; Montie, T C

1985-01-01

The regulation of amino acid chemotaxis by nitrogen was investigated in the gram-negative bacterium Pseudomonas aeruginosa. The quantitative capillary tube technique was used to measure chemotactic responses of bacteria to spatial gradients of amino acids and other attractants. Chemotaxis toward serine, arginine, and alpha-aminoisobutyrate was sharply dependent on the form in which nitrogen was presented to the bacteria. Bacteria grown on mineral salts-succinate with potassium nitrate gave responses to amino acids that were 2 to 3 times those of cells grown on ammonium sulfate and 10 to 20 times those of cells grown in mineral salts-succinate with Casamino Acids as the nitrogen source. A combination of ammonium sulfate and glutamate was as effective as Casamino Acids in depressing serine taxis. The threshold concentration for alpha-aminoisobutyrate taxis was consistently lower in nitrate-grown bacteria than in ammonia-grown bacteria. Responsiveness to sodium succinate, however, was not subject to regulation by nitrogen, and glucose chemotaxis was inhibited, rather than enhanced, in nitrate-grown bacteria. These results indicate that chemotaxis of P. aeruginosa toward amino acids is subject to regulation by nitrogen and that this regulation probably is expressed at the level of the chemoreceptors or transducers. PMID:3932326

Resource seeking strategies of zoosporic true fungi in heterogeneous soil habitats at the microscale level

PubMed Central

Gleason, Frank H.; Crawford, John W.; Neuhauser, Sigrid; Henderson, Linda E.; Lilje, Osu

2012-01-01

Zoosporic true fungi have frequently been identified in samples from soil and freshwater ecosystems using baiting and molecular techniques. In fact some species can be components of the dominant groups of microorganisms in particular soil habitats. Yet these microorganisms have not yet been directly observed growing in soil ecosystems. Significant physical characteristics and features of the three-dimensional structures of soils which impact microorganisms at the microscale level are discussed. A thorough knowledge of soil structures is important for studying the distribution of assemblages of these fungi and understanding their ecological roles along spatial and temporal gradients. A number of specific adaptations and resource seeking strategies possibly give these fungi advantages over other groups of microorganisms in soil ecosystems. These include chemotactic zoospores, mechanisms for adhesion to substrates, rhizoids which can penetrate substrates in small spaces, structures which are resistant to environmental extremes, rapid growth rates and simple nutritional requirements. These adaptations are discussed in the context of the characteristics of soils ecosystems. Recent advances in instrumentation have led to the development of new and more precise methods for studying microorganisms in three-dimensional space. New molecular techniques have made identification of microbes possible in environmental samples. PMID:22308003

Onset of nonlinearity in a stochastic model for auto-chemotactic advancing epithelia

NASA Astrophysics Data System (ADS)

Ben Amar, Martine; Bianca, Carlo

2016-09-01

We investigate the role of auto-chemotaxis in the growth and motility of an epithelium advancing on a solid substrate. In this process, cells create their own chemoattractant allowing communications among neighbours, thus leading to a signaling pathway. As known, chemotaxis provokes the onset of cellular density gradients and spatial inhomogeneities mostly at the front, a phenomenon able to predict some features revealed in in vitro experiments. A continuous model is proposed where the coupling between the cellular proliferation, the friction on the substrate and chemotaxis is investigated. According to our results, the friction and proliferation stabilize the front whereas auto-chemotaxis is a factor of destabilization. This antagonist role induces a fingering pattern with a selected wavenumber k0. However, in the planar front case, the translational invariance of the experimental set-up gives also a mode at k = 0 and the coupling between these two modes in the nonlinear regime is responsible for the onset of a Hopf-bifurcation. The time-dependent oscillations of patterns observed experimentally can be predicted simply in this continuous non-linear approach. Finally the effects of noise are also investigated below the instability threshold.

Lab-on-a-Chip Based Protein Crystallization

NASA Technical Reports Server (NTRS)

vanderWoerd, Mark J.; Brasseur, Michael M.; Spearing, Scott F.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

We are developing a novel technique with which we will grow protein crystals in very small volumes, utilizing chip-based, microfluidic ("LabChip") technology. This development, which is a collaborative effort between NASA's Marshall Space Flight Center and Caliper Technologies Corporation, promises a breakthrough in the field of protein crystal growth. Our initial results obtained from two model proteins, Lysozyme and Thaumatin, show that it is feasible to dispense and adequately mix protein and precipitant solutions on a nano-liter scale. The mixtures have shown crystal growth in volumes in the range of 10 nanoliters to 5 microliters. In addition, large diffraction quality crystals were obtained by this method. X-ray data from these crystals were shown to be of excellent quality. Our future efforts will include the further development of protein crystal growth with LabChip(trademark) technology for more complex systems. We will initially address the batch growth method, followed by the vapor diffusion method and the liquid-liquid diffusion method. The culmination of these chip developments is to lead to an on orbit protein crystallization facility on the International Space Station. Structural biologists will be invited to utilize the on orbit Iterative Biological Crystallization facility to grow high quality macromolecular crystals in microgravity.

Ecology and Physics of Bacterial Chemotaxis in the Ocean

PubMed Central

Seymour, Justin R.

2012-01-01

Summary: Intuitively, it may seem that from the perspective of an individual bacterium the ocean is a vast, dilute, and largely homogeneous environment. Microbial oceanographers have typically considered the ocean from this point of view. In reality, marine bacteria inhabit a chemical seascape that is highly heterogeneous down to the microscale, owing to ubiquitous nutrient patches, plumes, and gradients. Exudation and excretion of dissolved matter by larger organisms, lysis events, particles, animal surfaces, and fluxes from the sediment-water interface all contribute to create strong and pervasive heterogeneity, where chemotaxis may provide a significant fitness advantage to bacteria. The dynamic nature of the ocean imposes strong selective pressures on bacterial foraging strategies, and many marine bacteria indeed display adaptations that characterize their chemotactic motility as “high performance” compared to that of enteric model organisms. Fast swimming speeds, strongly directional responses, and effective turning and steering strategies ensure that marine bacteria can successfully use chemotaxis to very rapidly respond to chemical gradients in the ocean. These fast responses are advantageous in a broad range of ecological processes, including attaching to particles, exploiting particle plumes, retaining position close to phytoplankton cells, colonizing host animals, and hovering at a preferred height above the sediment-water interface. At larger scales, these responses can impact ocean biogeochemistry by increasing the rates of chemical transformation, influencing the flux of sinking material, and potentially altering the balance of biomass incorporation versus respiration. This review highlights the physical and ecological processes underpinning bacterial motility and chemotaxis in the ocean, describes the current state of knowledge of chemotaxis in marine bacteria, and summarizes our understanding of how these microscale dynamics scale up to affect ecosystem-scale processes in the sea. PMID:23204367

Ecology and physics of bacterial chemotaxis in the ocean.

PubMed

Stocker, Roman; Seymour, Justin R

2012-12-01

Intuitively, it may seem that from the perspective of an individual bacterium the ocean is a vast, dilute, and largely homogeneous environment. Microbial oceanographers have typically considered the ocean from this point of view. In reality, marine bacteria inhabit a chemical seascape that is highly heterogeneous down to the microscale, owing to ubiquitous nutrient patches, plumes, and gradients. Exudation and excretion of dissolved matter by larger organisms, lysis events, particles, animal surfaces, and fluxes from the sediment-water interface all contribute to create strong and pervasive heterogeneity, where chemotaxis may provide a significant fitness advantage to bacteria. The dynamic nature of the ocean imposes strong selective pressures on bacterial foraging strategies, and many marine bacteria indeed display adaptations that characterize their chemotactic motility as "high performance" compared to that of enteric model organisms. Fast swimming speeds, strongly directional responses, and effective turning and steering strategies ensure that marine bacteria can successfully use chemotaxis to very rapidly respond to chemical gradients in the ocean. These fast responses are advantageous in a broad range of ecological processes, including attaching to particles, exploiting particle plumes, retaining position close to phytoplankton cells, colonizing host animals, and hovering at a preferred height above the sediment-water interface. At larger scales, these responses can impact ocean biogeochemistry by increasing the rates of chemical transformation, influencing the flux of sinking material, and potentially altering the balance of biomass incorporation versus respiration. This review highlights the physical and ecological processes underpinning bacterial motility and chemotaxis in the ocean, describes the current state of knowledge of chemotaxis in marine bacteria, and summarizes our understanding of how these microscale dynamics scale up to affect ecosystem-scale processes in the sea.

* Central Growth Factor Loaded Depots in Bone Tissue Engineering Scaffolds for Enhanced Cell Attraction.

PubMed

Quade, Mandy; Knaack, Sven; Akkineni, Ashwini Rahul; Gabrielyan, Anastasia; Lode, Anja; Rösen-Wolff, Angela; Gelinsky, Michael

2017-08-01

Tissue engineering, the application of stem and progenitor cells in combination with an engineered extracellular matrix, is a promising strategy for bone regeneration. However, its success is limited by the lack of vascularization after implantation. The concept of in situ tissue engineering envisages the recruitment of cells necessary for tissue regeneration from the host environment foregoing ex vivo cell seeding of the scaffold. In this study, we developed a novel scaffold system for enhanced cell attraction, which is based on biomimetic mineralized collagen scaffolds equipped with a central biopolymer depot loaded with chemotactic agents. In humid milieu, as after implantation, the signaling factors are expected to slowly diffuse out of the central depot forming a gradient that stimulates directed cell migration toward the scaffold center. Heparin, hyaluronic acid, and alginate have been shown to be capable of depot formation. By using vascular endothelial growth factor (VEGF) as model factor, it was demonstrated that the release kinetics can be adjusted by varying the depot composition. While alginate and hyaluronic acid are able to reduce the initial burst and prolong the release of VEGF, the addition of heparin led to a much stronger retention that resulted in an almost linear release over 28 days. The biological activity of released VEGF was proven for all variants using an endothelial cell proliferation assay. Furthermore, migration experiments with endothelial cells revealed a relationship between the degree of VEGF retention and migration distance: cells invaded deepest in scaffolds containing a heparin-based depot indicating that the formation of a steep gradient is crucial for cell attraction. In conclusion, this novel in situ tissue engineering approach, specifically designed to recruit and accommodate endogenous cells upon implantation, appeared highly promising to stimulate cell invasion, which in turn would promote vascularization and finally new bone formation.

Mass transport in morphogenetic processes: A second gradient theory for volumetric growth and material remodeling

NASA Astrophysics Data System (ADS)

Ciarletta, P.; Ambrosi, D.; Maugin, G. A.

2012-03-01

In this work, we derive a novel thermo-mechanical theory for growth and remodeling of biological materials in morphogenetic processes. This second gradient hyperelastic theory is the first attempt to describe both volumetric growth and mass transport phenomena in a single-phase continuum model, where both stress- and shape-dependent growth regulations can be investigated. The diffusion of biochemical species (e.g. morphogens, growth factors, migration signals) inside the material is driven by configurational forces, enforced in the balance equations and in the set of constitutive relations. Mass transport is found to depend both on first- and on second-order material connections, possibly withstanding a chemotactic behavior with respect to diffusing molecules. We find that the driving forces of mass diffusion can be written in terms of covariant material derivatives reflecting, in a purely geometrical manner, the presence of a (first-order) torsion and a (second-order) curvature. Thermodynamical arguments show that the Eshelby stress and hyperstress tensors drive the rearrangement of the first- and second-order material inhomogeneities, respectively. In particular, an evolution law is proposed for the first-order transplant, extending a well-known result for inelastic materials. Moreover, we define the first stress-driven evolution law of the second-order transplant in function of the completely material Eshelby hyperstress. The theory is applied to two biomechanical examples, showing how an Eshelbian coupling can coordinate volumetric growth, mass transport and internal stress state, both in physiological and pathological conditions. Finally, possible applications of the proposed model are discussed for studying the unknown regulation mechanisms in morphogenetic processes, as well as for optimizing scaffold architecture in regenerative medicine and tissue engineering.

Organic acids from root exudates of banana help root colonization of PGPR strain Bacillus amyloliquefaciens NJN-6

PubMed Central

Yuan, Jun; Zhang, Nan; Huang, Qiwei; Raza, Waseem; Li, Rong; Vivanco, Jorge M.; Shen, Qirong

2015-01-01

The successful colonization of plant growth promoting rhizobacteria (PGPR) in the rhizosphere is an initial and compulsory step in the protection of plants from soil-borne pathogens. Therefore, it is necessary to evaluate the role of root exudates in the colonization of PGPR. Banana root exudates were analyzed by high pressure liquid chromatography (HPLC) which revealed exudates contained several organic acids (OAs) including oxalic, malic and fumaric acid. The chemotactic response and biofilm formation of Bacillus amyloliquefaciens NJN-6 were investigated in response to OA’s found in banana root exudates. Furthermore, the transcriptional levels of genes involved in biofilm formation, yqxM and epsD, were evaluated in response to OAs via quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Results suggested that root exudates containing the OAs both induced the chemotaxis and biofilm formation in NJN-6. In fact, the strongest chemotactic and biofilm response was found when 50 μM of OAs were applied. More specifically, malic acid showed the greatest chemotactic response whereas fumaric acid significantly induced biofilm formation by a 20.7–27.3% increase and therefore biofilm formation genes expression. The results showed banana root exudates, in particular the OAs released, play a crucial role in attracting and initiating PGPR colonization on the host roots. PMID:26299781

Cigarette smoke increases Toll-like receptor 4 and modifies lipopolysaccharide-mediated responses in airway epithelial cells

PubMed Central

Pace, Elisabetta; Ferraro, Maria; Siena, Liboria; Melis, Mario; Montalbano, Angela M; Johnson, Malcolm; Bonsignore, Maria R; Bonsignore, Giovanni; Gjomarkaj, Mark

2008-01-01

Airway epithelium is emerging as a regulator of innate immune responses to a variety of insults including cigarette smoke. The main goal of this study was to explore the effects of cigarette smoke extracts (CSE) on Toll-like receptor (TLR) expression and activation in a human bronchial epithelial cell line (16-HBE). The CSE increased the expression of TLR4 and the lipopolysaccharide (LPS) binding, the nuclear factor-κB (NF-κB) activation, the release of interleukin-8 (IL-8) and the chemotactic activity toward neutrophils. It did not induce TLR2 expression or extracellular signal-regulated signal kinase 1/2 (ERK1/2) activation. The LPS increased the expression of TLR4 and induced both NF-κB and ERK1/2 activation. The combined exposure of 16-HBE to CSE and LPS was associated with ERK activation rather than NF-κB activation and with a further increase of IL-8 release and of chemotactic activity toward neutrophils. Furthermore, CSE decreased the constitutive interferon-inducible protein-10 (IP-10) release and counteracted the effect of LPS in inducing both the IP-10 release and the chemotactic activity toward lymphocytes. In conclusion, cigarette smoke, by altering the expression and the activation of TLR4 via the preferential release of IL-8, may contribute to the accumulation of neutrophils within the airways of smokers. PMID:18217953

Effect of aliphatic, monocarboxylic, dicarboxylic, heterocyclic and sulphur-containing amino acids on Leishmania spp. chemotaxis.

PubMed

Diaz, E; Zacarias, A K; Pérez, S; Vanegas, O; Köhidai, L; Padrón-Nieves, M; Ponte-Sucre, A

2015-11-01

In the sand-fly mid gut, Leishmania promastigotes are exposed to acute changes in nutrients, e.g. amino acids (AAs). These metabolites are the main energy sources for the parasite, crucial for its differentiation and motility. We analysed the migratory behaviour and morphological changes produced by aliphatic, monocarboxylic, dicarboxylic, heterocyclic and sulphur-containing AAs in Leishmania amazonensis and Leishmania braziliensis and demonstrated that L-methionine (10-12 m), L-tryptophan (10-11 m), L-glutamine and L-glutamic acid (10-6 m), induced positive chemotactic responses, while L-alanine (10-7 m), L-methionine (10-11 and 10-7 m), L-tryptophan (10-11 m), L-glutamine (10-12 m) and L-glutamic acid (10-9 m) induced negative chemotactic responses. L-proline and L-cysteine did not change the migratory potential of Leishmania. The flagellum length of L. braziliensis, but not of L. amazonensis, decreased when incubated in hyperosmotic conditions. However, chemo-repellent concentrations of L-alanine (Hypo-/hyper-osmotic conditions) and L-glutamic acid (hypo-osmotic conditions) decreased L. braziliensis flagellum length and L-methionine (10-11 m, hypo-/hyper-osmotic conditions) decreased L. amazonensis flagellum length. This chemotactic responsiveness suggests that Leishmania discriminate between slight concentration differences of small and structurally closely related molecules and indicates that besides their metabolic effects, AAs play key roles linked to sensory mechanisms that might determine the parasite's behaviour.

Circulating promyelocytes and low levels of CD16 expression on polymorphonuclear leukocytes accompany early-onset periodontitis.

PubMed Central

Nemoto, E; Nakamura, M; Shoji, S; Horiuchi, H

1997-01-01

Early-onset periodontitis (EOP) is characterized by rapidly progressive alveolar bone loss, chemotactic defects of neutrophils, and significant familial aggregation. We found immature myeloid lineage cells, defined as promyelocytes, in the peripheral blood in patients with EOP. A hematological examination of peripheral blood cells showed normal reference values regarding cell proportions. Flow cytometry revealed significantly lower expression of CD16, a glycosylphosphatidylinositol (GPI)-anchored protein, on peripheral neutrophils in patients compared with those in age- and sex-matched healthy controls, whereas the levels of CD11a and CD11b expression were similar. The chemotactic response of neutrophils was lower toward not only formyl-methionyl-leucyl-phenylalanine but also complement fragment C5a than that of healthy controls. The expression of another GPI-anchored protein, CD14, was equally expressed by controls and patients. Therefore, the low level of CD16 expression was not due to the incomplete synthesis of the GPI anchor. GPI anchors of CD16 on neutrophils from controls and patients were both partially resistant to phosphatidylinositol-specific phospholipase C. The presence of promyelocytes in peripheral blood, low expression of CD16, and low chemotactic response of neutrophils suggest that patients with EOP have an abnormal maturation system in myeloid lineage cells in the bone marrow, which may be associated with the onset and course of EOP. PMID:9284170

A supplemented soft agar chemotaxis assay demonstrates the Helicobacter pylori chemotactic response to zinc and nickel

PubMed Central

Sanders, Lisa; Andermann, Tessa M.

2013-01-01

Directed motility, or chemotaxis, is required for Helicobacter pylori to establish infection in the stomach, although the full repertoire of this bacterium’s chemotactic responses is not yet known. Here we report that H. pylori responds to zinc as an attractant and nickel as a repellent. To reach this conclusion, we employed both a temporal chemotaxis assay based on bacterial reversals and a supplemented soft agar spatial assay. We refined the temporal assay using a previously described chemorepellent, acid, and found that H. pylori requires rich media with serum to maintain optimal swimming motility. Surprisingly, we found that some strains respond to acid as an attractant, and that the TlpC chemoreceptor correlated with whether acid was sensed as an attractant or repellent. Using this same assay, we detected weak repellent responses to nickel and copper, and a varied response to zinc. We thus developed an alternative spatial chemotactic assay called the supplemented soft agar assay, which utilizes soft agar medium supplemented with the test compound. With Escherichia coli, the attractant serine slowed overall bacterial migration, while the repellent nickel increased the speed of overall migration. In H. pylori we detected slowed migration with doubled tryptone media, as well as zinc, consistent with an attractant response. In contrast, nickel increased migration, consistent with repulsion. PMID:23139399

Misbalanced CXCL12 and CCL5 Chemotactic Signals in Vitiligo Onset and Progression.

PubMed

Rezk, Ahmed F; Kemp, Daria Marley; El-Domyati, Moetaz; El-Din, Wael Hosam; Lee, Jason B; Uitto, Jouni; Igoucheva, Olga; Alexeev, Vitali

2017-05-01

Generalized nonsegmental vitiligo is often associated with the activation of melanocyte-specific autoimmunity. Because chemokines play an important role in the maintenance of immune responses, we examined chemotactic signatures in cultured vitiligo melanocytes and skin samples of early (≤2 months) and advanced (≥6 months) vitiligo. Analysis showed that melanocytes in early lesions have altered expression of several chemotaxis-associated molecules, including elevated secretion of CXCL12 and CCL5. Higher levels of these chemokines coincided with prominent infiltration of the skin with antigen presenting cells (APCs) and T cells. Most of the intralesional APCs expressed the CD86 maturation marker and co-localized with T cells, particularly in early vitiligo lesions. These observations were confirmed by in vivo animal studies showing preferential recruitment of APCs and T cells to CXCL12- and CCL5-expressing transplanted melanocytes, immunotargeting of the chemokine-positive cells, continuous loss of the pigment-producing cells from the epidermis, and development of vitiligo-like lesions. Taken together, our studies show that melanocyte-derived CXCL12 and CCL5 support APC and T-cell recruitment, antigen acquisition, and T-cell activation in early vitiligo and reinforce the role of melanocyte-derived CXCL12 and CCL5 in activation of melanocyte-specific immunity and suggest inhibition of these chemotactic axes as a strategy for vitiligo stabilization. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Multiscale dynamics of biological cells with chemotactic interactions: From a discrete stochastic model to a continuous description

NASA Astrophysics Data System (ADS)

Alber, Mark; Chen, Nan; Glimm, Tilmann; Lushnikov, Pavel M.

2006-05-01

The cellular Potts model (CPM) has been used for simulating various biological phenomena such as differential adhesion, fruiting body formation of the slime mold Dictyostelium discoideum, angiogenesis, cancer invasion, chondrogenesis in embryonic vertebrate limbs, and many others. We derive a continuous limit of a discrete one-dimensional CPM with the chemotactic interactions between cells in the form of a Fokker-Planck equation for the evolution of the cell probability density function. This equation is then reduced to the classical macroscopic Keller-Segel model. In particular, all coefficients of the Keller-Segel model are obtained from parameters of the CPM. Theoretical results are verified numerically by comparing Monte Carlo simulations for the CPM with numerics for the Keller-Segel model.

Optimal chemotactic responses in stochastic environments

PubMed Central

Godány, Martin

2017-01-01

Although the “adaptive” strategy used by Escherichia coli has dominated our understanding of bacterial chemotaxis, the environmental conditions under which this strategy emerged is still poorly understood. In this work, we study the performance of various chemotactic strategies under a range of stochastic time- and space-varying attractant distributions in silico. We describe a novel “speculator” response in which the bacterium compare the current attractant concentration to the long-term average; if it is higher then they tumble persistently, while if it is lower than the average, bacteria swim away in search of more favorable conditions. We demonstrate how this response explains the experimental behavior of aerobically-grown Rhodobacter sphaeroides and that under spatially complex but slowly-changing nutrient conditions the speculator response is as effective as the adaptive strategy of E. coli. PMID:28644830

Pregnant human peripheral leukocyte migration during several late pregnancy clinical conditions: a cross-sectional observational study.

PubMed

Takeda, Jun; Fang, Xin; Olson, David M

2017-01-10

Parturition at term and preterm is characterized by sterile inflammatory processes occurring in the absence of infection whereby peripheral leukocytes infiltrate gestational tissues in response to chemotactic signals. In response to a homing signal, recruited leukocytes undergo diapedesis and extravasate through capillaries, migrating into stromal tissue. There they interact with resident immune and stromal cells to produce a mixture of matrix metalloproteinases, prostaglandins and cytokines including interleukin-1β (IL-1β) and IL-6 that in turn transform the uterus from pregnancy to parturition. Since migration is an early parturitional event our purpose was to study the migration of maternal peripheral blood leukocytes in response to a standard chemotactic signal during several different conditions of late pregnancy. We used a cross-sectional observational study design. Subjects were (sTL) spontaneous normal labour delivered vaginally at term, (TNL) elective caesarean section at term without labour, (PTL) preterm in labour, (PTNL) preterm not in labour, (TPTL) threatened preterm labour, and (pPROM) preterm with premature rupture of membranes. Leukocytes (100,000) obtained by venipuncture and chemotactic factor isolated from term labour fetal membranes were placed in the upper and lower halves, respectively, of a Boyden chamber separated by a filter with 3μm pores. Migrated leukocytes were assessed by flow cytometry. The number of leukocytes that migrated in 90 min was the primary outcome measure. Increased numbers of leukocytes from peripheral blood of women in labour (TL or PTL) or soon to go into labour (PPROM) migrated towards a chemotactic signal than did leukocytes from women not in labour (TNL, PTNL, or TPTL) (p < 0.0001). All pPROM delivered within 7d; TPTL delivered >30d. Receiver operating characteristic curve parameters indicated the cut-off point for delivery within 7d to be 37,082 leukocytes with sensitivity 78.1%, specificity 88.9%, positive predictive value 91.4%, negative predictive value 72.7%, and area under the curve 0.83. Leukocyte migration to a fetal membrane signal varies in a predictable fashion during various clinical situations of late gestation. This principle has the potential to be improved to become a clinical test to predict delivery.

E. coli chemotaxis and super-diffusion

NASA Astrophysics Data System (ADS)

Dobnikar, Jure; Matthäus, Franziska; Jagodic, Marko

2010-03-01

The bacteria E. coli actively propel by switching between clockwise and anti-clockwise rotation of the flagella attached to their cell membranes. This results in two modes of motion: tumbling and swimming. The switching between the two modes is coupled to the ligand sensing through the chemotactic signalling pathway inside the cell. We modelled the signalling pathway and performed numerical simulations of the chemotactic motion of a large number of E. coli bacteria under various external conditions. We have shown that under certain conditions the thermal noise in the level of receptor-bound CheR (an enzyme responsible for methylation of the receptor sites) leads to super-diffusive behaviour (L'evy walk) which is advantageous for the bacterial populations in environments with scarce food. Exerting external pressure we might observe evolution of the wild-type to the super-diffusive populations.

Isolation of an N-acetyl-DL-phenylalanine beta-naphthyl esterase from rabbit peritoneal polymorphonuclear leukocytes.

PubMed

Tsung, P; Kegeles, S W; Showell, H J; Becker, E L

1975-09-22

An N-acetyl-DL-phenylalanine beta-naphthyl esterase has been purified 26-fold from rabbit peritoneal polymorphonuclear leukocytes. The purified enzyme was inhibited by 10(-7) M p-nitrophenylethyl-5-chloropentylphosphonate. The apparent Km for hydrolysis of N-acetyl-DL-phenylalanine beta-naphthyl ester is 71 muM. Optimal reaction rates were observed at pH 6-8. No divalent cation requirement for the activation of the enzyme activity was observed. The esterase activity was neither inhibited nor stimulated by bacterial factor, complement component C5a, guanosine 3',5'-monophosphate (cyclic GMP) and adenosine 3',5'-monophosphate (cyclic AMP) which are attractants or repellents for polymorphonuclear leukocytes. High chemotactic activity was observed in the partially purified fraction of the enzyme. The chemotactic activity, like the enzyme activity, was completely inhibited by 10(-7) M phosphonate.

Peptides as modifiers of Na+-induced pinocytosis in starved Amoeba proteus.

PubMed

Josefsson, J O; Johansson, P

1985-01-01

Low concentrations of six peptide hormones; glucagon, vasoactive intestinal peptide, substance P, angiotensin II, lysine-vasopressin, arginine-vasopressin, and the chemotactic peptide fMet-Leu-Phe, activated the capacity for pinocytosis in starved Amoeba proteus. Competitive inhibitors of the chemotactic peptide in leucocytes inhibited activation by fMet-Leu-Phe, suggesting that its action in the amoeba is mediated by specific receptors. The opioid peptides, beta-endorphin, dynorphin (1-13) and leu-enkephalin abolished through a naloxone-sensitive mechanism activation by hormones and several other activating agents. Also, low concentrations of beef and pork insulin inhibited activation by peptide hormones. An insulin analogue of low potency in mammalian cells was inactive in the amoeba. These results support the hypothesis that besides opioid receptors, there may be insulin receptors and possibly receptors for several other peptide hormones in Amoeba proteus.

Evidence for a novel chemotactic C1q domain-containing factor in the leech nerve cord.

PubMed

Tahtouh, Muriel; Croq, Françoise; Vizioli, Jacopo; Sautiere, Pierre-Eric; Van Camp, Christelle; Salzet, Michel; Daha, Mohamed R; Pestel, Joël; Lefebvre, Christophe

2009-02-01

In vertebrates, central nervous system (CNS) protection is dependent on many immune cells including microglial cells. Indeed, activated microglial cells are involved in neuroinflammation mechanisms by interacting with numerous immune factors. Unlike vertebrates, some lophotrochozoan invertebrates can fully repair their CNS following injury. In the medicinal leech Hirudo medicinalis, the recruitment of microglial cells at the lesion site is essential for sprouting of injured axons. Interestingly, a new molecule homologous to vertebrate C1q was characterized in leech, named HmC1q (for H. medicinalis) and detected in neurons and glial cells. In chemotaxis assays, leech microglial cells were demonstrated to respond to human C1q. The chemotactic activity was reduced when microglia was preincubated with signaling pathway inhibitors (Pertussis Toxin or wortmannin) or anti-human gC1qR antibody suggesting the involvement of gC1qR in C1q-mediated migration in leech. Assays using cells preincubated with NO chelator (cPTIO) showed that C1q-mediated migration was associated to NO production. Of interest, by using anti-HmC1q antibodies, HmC1q released in the culture medium was shown to exhibit a similar chemotactic effect on microglial cells as human C1q. In summary, we have identified, for the first time, a molecule homologous to mammalian C1q in leech CNS. Its chemoattractant activity on microglia highlights a new investigation field leading to better understand leech CNS repair mechanisms.

Matrix Metalloproteinase-8 Facilitates Neutrophil Migration through the Corneal Stromal Matrix by Collagen Degradation and Production of the Chemotactic Peptide Pro-Gly-Pro

PubMed Central

Lin, Michelle; Jackson, Patricia; Tester, Angus M.; Diaconu, Eugenia; Overall, Christopher M.; Blalock, J. Edwin; Pearlman, Eric

2008-01-01

Matrix metalloproteinase (MMP)-8 and MMP-9 play several roles in inflammation, including degradation of extracellular matrix (ECM) components and regulation of cytokine activity. To determine the roles of MMP-8 and MMP-9 in a neutrophil-dependent inflammatory response, we used a murine model of corneal inflammation in which LPS is injected into the corneal stroma. In contrast to wild-type mice, we found that i) lipopolysaccharide (LPS)-injected CXCR2−/− corneas had impaired neutrophil infiltration and did not express either MMP-8 or MMP-9; ii) neutrophil migration through the central cornea was impaired in Mmp8−/−, but not Mmp9−/−, mice; iii) neutrophil migration was inhibited in collagenase-resistant mice; iv) the chemotactic Pro-Gly-Pro (PGP) tripeptide that binds CXCR2 was decreased in CXCR2−/− mice; v) PGP production was impaired in Mmp8−/− corneas; and vi) neutralizing anti-PGP antibody did not inhibit neutrophil infiltration in Mmp8−/− mice. We found no effects of MMP-8 on LPS-induced CXC chemokine (LIX, or CXCL5)-induced neutrophil recruitment or on LPS-induced CXC chemokine production. Together, these studies indicate that neutrophils contribute to the production of both MMP-8 and MMP-9 in LPS-injected corneas and that MMP-8 regulates neutrophil migration through the dense collagenous ECM of the corneal stroma by generating chemotactic PGP during inflammation. PMID:18556780

Extracellular ATP mediates the late phase of neutrophil recruitment to the lung in murine models of acute lung injury.

PubMed

Shah, Dilip; Romero, Freddy; Stafstrom, William; Duong, Michelle; Summer, Ross

2014-01-01

Acute lung injury (ALI) is a severe inflammatory condition whose pathogenesis is irrevocably linked to neutrophil emigration to the lung. Activation and recruitment of neutrophils to the lung is mostly attributable to local production of the chemokines. However, much of our understanding of neutrophil recruitment to the lung is based on studies focusing on early time points after initiation of injury. In this study, we sought to evaluate the extended temporal relationship between neutrophil chemotactic factor expression and influx of neutrophils into the lung after intratracheal administration of either LPS or bleomycin. In both models, results demonstrated two phases of neutrophil chemotactic factor expression; first, an early phase characterized by high levels of CXCL1/keratinocyte-derived chemokine, CXCL2/monocyte-inhibitory protein-2, and CXCL5/LPS-induced chemokine expression, and second, a late phase distinguished by increases in extracellular ATP. Furthermore, we show that strategies aimed at either enhancing ATP catabolism (ip ecto-5'-nucleotidase administration) or inhibiting glycolytic ATP production (ip 2-deoxy-d-glucose treatment) reduce extracellular ATP accumulation, limit vascular leakage, and effectively block the late, but not the early, stages of neutrophil recruitment to the lung after LPS instillation. In conclusion, this study illustrates that neutrophil recruitment to the lung is mediated by the time-dependent expression of chemotactic factors and suggests that novel strategies, which reduce extracellular ATP accumulation, may attenuate late neutrophil recruitment and limit lung injury during ALI.

Extracellular ATP mediates the late phase of neutrophil recruitment to the lung in murine models of acute lung injury

PubMed Central

Shah, Dilip; Romero, Freddy; Stafstrom, William; Duong, Michelle

2013-01-01

Acute lung injury (ALI) is a severe inflammatory condition whose pathogenesis is irrevocably linked to neutrophil emigration to the lung. Activation and recruitment of neutrophils to the lung is mostly attributable to local production of the chemokines. However, much of our understanding of neutrophil recruitment to the lung is based on studies focusing on early time points after initiation of injury. In this study, we sought to evaluate the extended temporal relationship between neutrophil chemotactic factor expression and influx of neutrophils into the lung after intratracheal administration of either LPS or bleomycin. In both models, results demonstrated two phases of neutrophil chemotactic factor expression; first, an early phase characterized by high levels of CXCL1/keratinocyte-derived chemokine, CXCL2/monocyte-inhibitory protein-2, and CXCL5/LPS-induced chemokine expression, and second, a late phase distinguished by increases in extracellular ATP. Furthermore, we show that strategies aimed at either enhancing ATP catabolism (ip ecto-5′-nucleotidase administration) or inhibiting glycolytic ATP production (ip 2-deoxy-d-glucose treatment) reduce extracellular ATP accumulation, limit vascular leakage, and effectively block the late, but not the early, stages of neutrophil recruitment to the lung after LPS instillation. In conclusion, this study illustrates that neutrophil recruitment to the lung is mediated by the time-dependent expression of chemotactic factors and suggests that novel strategies, which reduce extracellular ATP accumulation, may attenuate late neutrophil recruitment and limit lung injury during ALI. PMID:24285266

The group migration of Dictyostelium cells is regulated by extracellular chemoattractant degradation.

PubMed

Garcia, Gene L; Rericha, Erin C; Heger, Christopher D; Goldsmith, Paul K; Parent, Carole A

2009-07-01

Starvation of Dictyostelium induces a developmental program in which cells form an aggregate that eventually differentiates into a multicellular structure. The aggregate formation is mediated by directional migration of individual cells that quickly transition to group migration in which cells align in a head-to-tail manner to form streams. Cyclic AMP acts as a chemoattractant and its production, secretion, and degradation are highly regulated. A key protein is the extracellular phosphodiesterase PdsA. In this study we examine the role and localization of PdsA during chemotaxis and streaming. We find that pdsA(-) cells respond chemotactically to a narrower range of chemoattractant concentrations compared with wild-type (WT) cells. Moreover, unlike WT cells, pdsA(-) cells do not form streams at low cell densities and form unusual thick and transient streams at high cell densities. We find that the intracellular pool of PdsA is localized to the endoplasmic reticulum, which may provide a compartment for storage and secretion of PdsA. Because we find that cAMP synthesis is normal in cells lacking PdsA, we conclude that signal degradation regulates the external cAMP gradient field generation and that the group migration behavior of these cells is compromised even though their signaling machinery is intact.

Glucose induces delocalization of a flagellar biosynthesis protein from the flagellated pole.

PubMed

Park, Soyoung; Park, Young-Ha; Lee, Chang-Ro; Kim, Yeon-Ran; Seok, Yeong-Jae

2016-09-01

To survive in a continuously changing environment, bacteria sense concentration gradients of attractants or repellents, and purposefully migrate until a more favourable habitat is encountered. While glucose is known as the most effective attractant, the flagellar biosynthesis and hence chemotactic motility has been known to be repressed by glucose in some bacteria. To date, the only known regulatory mechanism of the repression of flagellar synthesis by glucose is via downregulation of the cAMP level, as shown in a few members of the family Enterobacteriaceae. Here we show that, in Vibrio vulnificus, the glucose-mediated inhibition of flagellar motility operates by a completely different mechanism. In the presence of glucose, EIIA(Glc) is dephosphorylated and inhibits the polar localization of FapA (flagellar assembly protein A) by sequestering it from the flagellated pole. A loss or delocalization of FapA results in a complete failure of the flagellar biosynthesis and motility. However, when glucose is depleted, EIIA(Glc) is phosphorylated and releases FapA such that free FapA can be localized back to the pole and trigger flagellation. Together, these data provide new insight into a bacterial strategy to reach and stay in the glucose-rich area. © 2016 John Wiley & Sons Ltd.

The Group Migration of Dictyostelium Cells Is Regulated by Extracellular Chemoattractant Degradation

PubMed Central

Garcia, Gene L.; Rericha, Erin C.; Heger, Christopher D.; Goldsmith, Paul K.

2009-01-01

Starvation of Dictyostelium induces a developmental program in which cells form an aggregate that eventually differentiates into a multicellular structure. The aggregate formation is mediated by directional migration of individual cells that quickly transition to group migration in which cells align in a head-to-tail manner to form streams. Cyclic AMP acts as a chemoattractant and its production, secretion, and degradation are highly regulated. A key protein is the extracellular phosphodiesterase PdsA. In this study we examine the role and localization of PdsA during chemotaxis and streaming. We find that pdsA− cells respond chemotactically to a narrower range of chemoattractant concentrations compared with wild-type (WT) cells. Moreover, unlike WT cells, pdsA− cells do not form streams at low cell densities and form unusual thick and transient streams at high cell densities. We find that the intracellular pool of PdsA is localized to the endoplasmic reticulum, which may provide a compartment for storage and secretion of PdsA. Because we find that cAMP synthesis is normal in cells lacking PdsA, we conclude that signal degradation regulates the external cAMP gradient field generation and that the group migration behavior of these cells is compromised even though their signaling machinery is intact. PMID:19477920

Semaphorin 3 C drives epithelial-to-mesenchymal transition, invasiveness, and stem-like characteristics in prostate cells.

PubMed

Tam, Kevin J; Hui, Daniel H F; Lee, Wilson W; Dong, Mingshu; Tombe, Tabitha; Jiao, Ivy Z F; Khosravi, Shahram; Takeuchi, Ario; Peacock, James W; Ivanova, Larissa; Moskalev, Igor; Gleave, Martin E; Buttyan, Ralph; Cox, Michael E; Ong, Christopher J

2017-09-13

Prostate cancer (PCa) is among the most commonly-occurring cancers worldwide and a leader in cancer-related deaths. Local non-invasive PCa is highly treatable but limited treatment options exist for those with locally-advanced and metastatic forms of the disease underscoring the need to identify mechanisms mediating PCa progression. The semaphorins are a large grouping of membrane-associated or secreted signalling proteins whose normal roles reside in embryogenesis and neuronal development. In this context, semaphorins help establish chemotactic gradients and direct cell movement. Various semaphorin family members have been found to be up- and down-regulated in a number of cancers. One family member, Semaphorin 3 C (SEMA3C), has been implicated in prostate, breast, ovarian, gastric, lung, and pancreatic cancer as well as glioblastoma. Given SEMA3C's roles in development and its augmented expression in PCa, we hypothesized that SEMA3C promotes epithelial-to-mesenchymal transition (EMT) and stem-like phenotypes in prostate cells. In the present study we show that ectopic expression of SEMA3C in RWPE-1 promotes the upregulation of EMT and stem markers, heightened sphere-formation, and cell plasticity. In addition, we show that SEMA3C promotes migration and invasion in vitro and cell dissemination in vivo.

Terahertz artificial material based on integrated metal-rod-array for phase sensitive fluid detection.

PubMed

You, Borwen; Chen, Ching-Yu; Yu, Chin-Ping; Liu, Tze-An; Hattori, Toshiaki; Lu, Ja-Yu

2017-04-17

A terahertz artificial material composed of metal rod array is experimentally investigated on its transmission spectral property and successfully incorporated into microfluidics as a miniaturized terahertz waveguide with an extended optical-path-length for label-free fluidic sensing. Theoretical and experimental characterizations of terahertz transmission spectra show that the wave guidance along the metal rod array originates from the resonance of transverse-electric-polarized waves within the metal rod slits. The extended optical path length along three layers of metal-rod-array enables terahertz waves sufficiently overlapping the fluid molecules embedded among the rods, leading to strongly enhanced phase change by approximately one order of magnitude compared with the blank metal-parallel-plate waveguide. Based on the enhanced phase sensitivity, three kinds of colorless liquid analytes, namely, acetone, methanol, and ethanol, with different dipole moments are identified in situ using the metal-rod-array-based microfluidic sensor. The detection limit in molecular amounts of a liquid analyte is experimentally demonstrated to be less than 0.1 mmol, corresponding to 2.7 μmol/mm². The phase sensitive terahertz metal-rod-array-based sensor potentially has good adaptability in lab-chip technology for various practical applications, such as industrial toxic fluid detection and medical breath inspection.

Biodegradation of naphthalene and anthracene by chemo-tactically active rhizobacteria of populus deltoides

PubMed Central

Bisht, Sandeep; Pandey, Piyush; Sood, Anchal; Sharma, Shivesh; Bisht, N. S.

2010-01-01

Several naphthalene and anthracene degrading bacteria were isolated from rhizosphere of Populus deltoides, which were growing in non-contaminated soil. Among these, four isolates, i.e. Kurthia sp., Micrococcus varians, Deinococcus radiodurans and Bacillus circulans utilized chrysene, benzene, toluene and xylene, in addition to anthracene and naphthalene. Kurthia sp and B. circulans showed positive chemotactic response for naphthalene and anthracene. The mean growth rate constant (K) of isolates were found to increase with successive increase in substrate concentration (0.5 to 1.0 mg/50ml). B. circulans SBA12 and Kurthia SBA4 degraded 87.5% and 86.6% of anthracene while, Kurthia sp. SBA4, B. circulans SBA12, and M. varians SBA8 degraded 85.3 %, 95.8 % and 86.8 % of naphthalene respectively after 6 days of incubation as determined by HPLC analysis. PMID:24031572

Chemotactic Activity of Cyclophilin A in the Skin Mucus of Yellow Catfish (Pelteobagrus fulvidraco) and Its Active Site for Chemotaxis

PubMed Central

Dawar, Farman Ullah; Tu, Jiagang; Xiong, Yang; Lan, Jiangfeng; Dong, Xing Xing; Liu, Xiaoling; Khattak, Muhammad Nasir Khan; Mei, Jie; Lin, Li

2016-01-01

Fish skin mucus is a dynamic barrier for invading pathogens with a variety of anti-microbial enzymes, including cyclophilin A (CypA), a multi-functional protein with peptidyl-prolyl cis/trans isomerase (PPIase) activity. Beside various other immunological functions, CypA induces leucocytes migration in vitro in teleost. In the current study, we have discovered several novel immune-relevant proteins in yellow catfish skin mucus by mass spectrometry (MS). The CypA present among them was further detected by Western blot. Moreover, the CypA present in the skin mucus displayed strong chemotactic activity for yellow catfish leucocytes. Interestingly, asparagine (like arginine in mammals) at position 69 was the critical site in yellow catfish CypA involved in leucocyte attraction. These novel efforts do not only highlight the enzymatic texture of skin mucus, but signify CypA to be targeted for anti-inflammatory therapeutics. PMID:27589721

Termitarium-Inhabiting Bacillus spp. Enhanced Plant Growth and Bioactive Component in Turmeric (Curcuma longa L.).

PubMed

Chauhan, Ankit Kumar; Maheshwari, Dinesh Kumar; Dheeman, Shrivardhan; Bajpai, Vivek K

2017-02-01

Curcumin (diferuloyl methane) is the main bioactive component of turmeric (Curcuma longa L.) having remarkable multipotent medicinal and therapeutic applications. Two Bacilli isolated from termitarium soil and identified as Bacillus endophyticus TSH42 and Bacillus cereus TSH77 were used for bacterization of rhizome for raising C. longa ver. suguna for growth and enhancement. Both the strains showed remarkable PGP activities and also chemotactic in nature with high chemotactic index. Turmeric plants bacterized with strains B. endophyticus TSH42 and B. cereus TSH77 individually and in combination increased plant growth and turmeric production up to 18% in field trial in comparison to non-bacterized plants. High-performance liquid chromatography analysis was performed to determine the content of curcumin, which showed concentration of curcumin in un-inoculated turmeric as 3.66 g which increased by 13.6% (4.16 g) when combination of TSH42 and TSH77 was used.

[Inhibition of monocytes adhesion to the intima of arterial wall by local expression of antisense monocyte chemotactic protein-1].

PubMed

Wu, Q; Qiao, H; Wang, Z; Zhang, H; Liu, P; Xu, M; Ren, G; Zhao, S; She, M

2000-04-01

To study the mechanism of monocyte recruitment in atherogenesis and to clarify the effect of monocyte chemotactic protein-1 (MCP-1) in this process. Femoral arteries isolated from the rabbits which had been fed with a high cholesterol diet and locally perfused with MM-LDL within the artery beforehand, were used as the models. Antisense MCP-1cDNA was transferred into the arterial wall by injecting recombinant LNCX-anti-MCP-1/liposomal complex in the femoral sheath and the periarterial tissue. Expression of antisense MCP-1 mediated by recombinant LNCX plasmid/lipsomal complex gene transfer enabled to inhibit MCP-1 gene expression and adhesion of monocyte to the intima. MCP-1 plays an important role on the recruitment of monocytes in the arterial wall, which provides a potential clue in developing a gene therapy project for the prevention and treatment of atherogenesis.

Effect of conglutinin on phagocytic activity of bovine granulocytes.

PubMed

Dec, M; Wernicki, A; Puchalski, A; Urban-Chmiel, R; Radej, S

2012-01-01

In the present study we investigated the effect of bovine conglutinin on the phagocytic activity of leukocytes. We measured both the chemotactic activity of conglutinin and its effect on the internalization of zymosan particles and E. coli by granulocytes. We also assessed the binding of conglutinin to various microorganisms isolated from clinical cases in cattle. We showed that conglutinin binds strongly to the surface of yeast cells and to mannan-rich zymosan particles, while weak binding was observed in the case of the bacterial strains tested, including those whose O antigen is composed of mannan. Conglutinin (1-10 microg/ml) neither acts as a chemotactic factor for peripheral blood leukocytes nor affects ingestion of E. coli by granulocytes. However, as flow cytometry based assay showed, conglutinin (0.1-1 microg/ml) increased ingestion of zymosan expressed as mean fluorescence intensity (MFI) of positive cells.

Spongionella Secondary Metabolites, Promising Modulators of Immune Response through CD147 Receptor Modulation

PubMed Central

Sánchez, Jon Andoni; Alfonso, Amparo; Rodriguez, Ines; Alonso, Eva; Cifuentes, José Manuel; Bermudez, Roberto; Rateb, Mostafa E.; Jaspars, Marcel; Houssen, Wael E.; Ebel, Rainer; Tabudravu, Jioji; Botana, Luís M.

2016-01-01

The modulation of the immune system can have multiple applications such as cancer treatment, and a wide type of processes involving inflammation where the potent chemotactic agent cyclophilin A (Cyp A) is implicated. The Porifera phylum, in which Spongionella is encompassed, is the main producer of marine bioactive compounds. Four secondary metabolites obtained from Spongionella (Gracilin H, A, L, and Tetrahydroaplysulphurin-1) were described to hit Cyp A and to block the release of inflammation mediators. Based on these results, some role of Spongionella compounds on other steps of the signaling pathway mediated by this chemotactic agent can be hypothesized. In the present paper, we studied the effect of these four compounds on the surface membrane CD147 receptor expression, on the extracellular levels of Cyp A and on the ability to migrate of concanavalin (Con A)-activated T lymphocytes. Similar to a well-known immunosuppressive agent cyclosporine A (CsA), Gracilin H, A, L, and tetrahydroaplysulphurin-1 were able to reduce the CD147 membrane expression and to block the release of Cyp A to the medium. Besides, by using Cyp A as chemotactic agent, T cell migration was inhibited when cells were previously incubated with Gracilin A and Gracilin L. These positive results lead us to test the in vivo effect of Gracilin H and L in a mouse ear delayed hypersensitive reaction. Thus, both compounds efficiently reduce the ear swelling as well as the inflammatory cell infiltration. These results provide more evidences for their potential therapeutic application in immune-related diseases of Spongionella compounds. PMID:27822214

Spongionella Secondary Metabolites, Promising Modulators of Immune Response through CD147 Receptor Modulation.

PubMed

Sánchez, Jon Andoni; Alfonso, Amparo; Rodriguez, Ines; Alonso, Eva; Cifuentes, José Manuel; Bermudez, Roberto; Rateb, Mostafa E; Jaspars, Marcel; Houssen, Wael E; Ebel, Rainer; Tabudravu, Jioji; Botana, Luís M

2016-01-01

The modulation of the immune system can have multiple applications such as cancer treatment, and a wide type of processes involving inflammation where the potent chemotactic agent cyclophilin A (Cyp A) is implicated. The Porifera phylum, in which Spongionella is encompassed, is the main producer of marine bioactive compounds. Four secondary metabolites obtained from Spongionella (Gracilin H, A, L, and Tetrahydroaplysulphurin-1) were described to hit Cyp A and to block the release of inflammation mediators. Based on these results, some role of Spongionella compounds on other steps of the signaling pathway mediated by this chemotactic agent can be hypothesized. In the present paper, we studied the effect of these four compounds on the surface membrane CD147 receptor expression, on the extracellular levels of Cyp A and on the ability to migrate of concanavalin (Con A)-activated T lymphocytes. Similar to a well-known immunosuppressive agent cyclosporine A (CsA), Gracilin H, A, L, and tetrahydroaplysulphurin-1 were able to reduce the CD147 membrane expression and to block the release of Cyp A to the medium. Besides, by using Cyp A as chemotactic agent, T cell migration was inhibited when cells were previously incubated with Gracilin A and Gracilin L. These positive results lead us to test the in vivo effect of Gracilin H and L in a mouse ear delayed hypersensitive reaction. Thus, both compounds efficiently reduce the ear swelling as well as the inflammatory cell infiltration. These results provide more evidences for their potential therapeutic application in immune-related diseases of Spongionella compounds.

Chemotactic preferences govern competition and pattern formation in simulated two-strain microbial communities.

PubMed

Centler, Florian; Thullner, Martin

2015-01-01

Substrate competition is a common mode of microbial interaction in natural environments. While growth properties play an important and well-studied role in competition, we here focus on the influence of motility. In a simulated two-strain community populating a homogeneous two-dimensional environment, strains competed for a common substrate and only differed in their chemotactic preference, either responding more sensitively to a chemoattractant excreted by themselves or responding more sensitively to substrate. Starting from homogeneous distributions, three possible behaviors were observed depending on the competitors' chemotactic preferences: (i) distributions remained homogeneous, (ii) patterns formed but dissolved at a later time point, resulting in a shifted community composition, and (iii) patterns emerged and led to the extinction of one strain. When patterns formed, the more aggregating strain populated the core of microbial aggregates where starving conditions prevailed, while the less aggregating strain populated the more productive zones at the fringe or outside aggregates, leading to a competitive advantage of the less aggregating strain. The presence of a competitor was found to modulate a strain's behavior, either suppressing or promoting aggregate formation. This observation provides a potential mechanism by which an aggregated lifestyle might evolve even if it is initially disadvantageous. Adverse effects can be avoided as a competitor hinders aggregate formation by a strain which has just acquired this ability. The presented results highlight both, the importance of microbial motility for competition and pattern formation, and the importance of the temporal evolution, or history, of microbial communities when trying to explain an observed distribution.

Chemotactic Cues for NOTCH1-Dependent Leukemia

PubMed Central

Piovan, Erich; Tosello, Valeria; Amadori, Alberto; Zanovello, Paola

2018-01-01

The NOTCH signaling pathway is a conserved signaling cascade that regulates many aspects of development and homeostasis in multiple organ systems. Aberrant activity of this signaling pathway is linked to the initiation and progression of several hematological malignancies, exemplified by T-cell acute lymphoblastic leukemia (T-ALL). Interestingly, frequent non-mutational activation of NOTCH1 signaling has recently been demonstrated in B-cell chronic lymphocytic leukemia (B-CLL), significantly extending the pathogenic significance of this pathway in B-CLL. Leukemia patients often present with high-blood cell counts, diffuse disease with infiltration of the bone marrow, secondary lymphoid organs, and diffusion to the central nervous system (CNS). Chemokines are chemotactic cytokines that regulate migration of cells between tissues and the positioning and interactions of cells within tissue. Homeostatic chemokines and their receptors have been implicated in regulating organ-specific infiltration, but may also directly and indirectly modulate tumor growth. Recently, oncogenic NOTCH1 has been shown to regulate infiltration of leukemic cells into the CNS hijacking the CC-chemokine ligand 19/CC-chemokine receptor 7 chemokine axis. In addition, a crucial role for the homing receptor axis CXC-chemokine ligand 12/CXC-chemokine receptor 4 has been demonstrated in leukemia maintenance and progression. Moreover, the CCL25/CCR9 axis has been implicated in the homing of leukemic cells into the gut, particularly in the presence of phosphatase and tensin homolog tumor suppressor loss. In this review, we summarize the latest developments regarding the role of NOTCH signaling in regulating the chemotactic microenvironmental cues involved in the generation and progression of T-ALL and compare these findings to B-CLL. PMID:29666622

The importance of interleukin-8 as a neutrophil chemoattractant in the lungs of cattle with pneumonic pasteurellosis.

PubMed Central

Caswell, J L; Middleton, D M; Gordon, J R

2001-01-01

Interleukin-8 (IL-8), an in vitro and in vivo neutrophil chemoattractant, is expressed at high levels in the lesions observed in bovine pneumonic pasteurellosis. Because of the role of neutrophils in the pathogenesis of pneumonic pasteurellosis, we investigated the relative importance of IL-8 as a neutrophil chemoattractant in this disease. Bronchoalveolar lavage (BAL) fluid was harvested from calves experimentally infected with bovine herpesvirus-1 and challenged with Mannheimia haemolytica. Neutrophil chemotactic activity was measured in pneumonic BAL fluid samples treated with a neutralizing monoclonal antibody to ovine IL-8, and compared to the activity in samples treated with an isotype-matched control antibody. Bronchoalveolar lavage fluid was analyzed at a dilution which induced a half-maximal response, and the concentrations of antibody were optimized in a preliminary experiment. Following incubation of replicate samples of diluted pneumonic bovine BAL fluid with 70 microg/mL of IL-8-neutralizing antibody or control antibody, the neutrophil chemotactic activities of the samples were determined using an in vitro microchemotaxis assay. Overall, pretreatment of BAL fluid samples with neutralizing anti-IL-8 antibody reduced neutrophil chemotactic activity by 15% to 60%, compared to pretreatment with control antibody. This effect was highly significant (P < 0.001), and was present in 5 of 5 samples. These data indicate that IL-8 is an important neutrophil chemoattractant in calves with pneumonic pasteurellosis, but that mediators with actions redundant to those of IL-8 must also be present in the lesions. PMID:11768129

Chemotaxis by natural populations of coral reef bacteria.

PubMed

Tout, Jessica; Jeffries, Thomas C; Petrou, Katherina; Tyson, Gene W; Webster, Nicole S; Garren, Melissa; Stocker, Roman; Ralph, Peter J; Seymour, Justin R

2015-08-01

Corals experience intimate associations with distinct populations of marine microorganisms, but the microbial behaviours underpinning these relationships are poorly understood. There is evidence that chemotaxis is pivotal to the infection process of corals by pathogenic bacteria, but this evidence is limited to experiments using cultured isolates under laboratory conditions. We measured the chemotactic capabilities of natural populations of coral-associated bacteria towards chemicals released by corals and their symbionts, including amino acids, carbohydrates, ammonium and dimethylsulfoniopropionate (DMSP). Laboratory experiments, using a modified capillary assay, and in situ measurements, using a novel microfabricated in situ chemotaxis assay, were employed to quantify the chemotactic responses of natural microbial assemblages on the Great Barrier Reef. Both approaches showed that bacteria associated with the surface of the coral species Pocillopora damicornis and Acropora aspera exhibited significant levels of chemotaxis, particularly towards DMSP and amino acids, and that these levels of chemotaxis were significantly higher than that of bacteria inhabiting nearby, non-coral-associated waters. This pattern was supported by a significantly higher abundance of chemotaxis and motility genes in metagenomes within coral-associated water types. The phylogenetic composition of the coral-associated chemotactic microorganisms, determined using 16S rRNA amplicon pyrosequencing, differed from the community in the seawater surrounding the coral and comprised known coral associates, including potentially pathogenic Vibrio species. These findings indicate that motility and chemotaxis are prevalent phenotypes among coral-associated bacteria, and we propose that chemotaxis has an important role in the establishment and maintenance of specific coral-microbe associations, which may ultimately influence the health and stability of the coral holobiont.

Role of Chemotaxis in the Ecology of Denitrifiers

PubMed Central

Kennedy, Michael J.; Lawless, James G.

1985-01-01

A modification of the Adler capillary assay was used to evaluate the chemotactic responses of several denitrifiers to nitrate and nitrite. Strong positive chemotaxis was observed to NO3− and NO2− by soil isolates of Pseudomonas aeruginosa, Pseudomonas fluorescens, and Pseudomonas stutzeri, with the peak response occurring at 10−3 M for both attractants. In addition, a strong chemoattraction to serine (peak response at 10−2 M), tryptone, and a soil extract, but not to NH4+, was observed for all denitrifiers tested. Chemotaxis was not dependent on a previous growth on NO3−, NO2−, or a soil extract, and the chemoattraction to NO3− occurred when the bacteria were grown aerobically or anaerobically. However, the best response to NO3− was usually observed when the cells were grown aerobically with 10 mM NO3− in the growth medium. Capillary tubes containing 10−3 M NO3− submerged into soil-water mixtures elicited a significant chemotactic response to NO3− by the indigenous soil microflora, the majority of which were Pseudomonas spp. A chemotactic strain of P. fluorescens also was shown to survive significantly better in aerobic and anaerobic soils than was a nonmotile strain of the same species. Both strains had equal growth rates in liquid cultures. Thus, chemotaxis may be one mechanism by which denitrifiers successfully compete for available NO3− and NO2−, and which may facilitate the survival of naturally occurring populations of some denitrifiers. PMID:16346690

Threshold levels of ERK activation for chemotactic migration differ for NGF and EGF in rat pheochromocytoma PC12 cells.

PubMed

Ho, W C; Uniyal, S; Zhou, H; Morris, V L; Chan, B M C

2005-03-01

In a previous study, we show that stimulation of chemotaxis in rat pheochromocytoma PC12 cells by nerve growth factor (NGF) and epidermal growth factor (EGF) requires activation of the RAS-ERK signaling pathway. In this study, we compared the threshold levels of ERK activation required for EGF and NGF-stimulated chemotaxis in PC12 cells. The threshold ERK activity required for NGF to stimulate chemotaxis was approximately 30% lower than that for EGF. PD98059 treatment inhibited EGF stimulation of growth and chemotaxis; however, stimulation of chemotaxis required an EGF concentration approximately 10 times higher than for stimulation of PC12 cell growth. Thus, ERK-dependent cellular functions can be differentially elicited by the concentration of EGF. Also, treatment of PC12 cells with the PI3-K inhibitor LY294002 reduced ERK activation by NGF; thus, higher NGF concentrations were required to initiate chemotaxis and to achieve the same maximal chemotactic response seen in untreated PC12 cells. Therefore, the threshold NGF concentration to stimulate chemotaxis could be adjusted by the crosstalk between the ERK and PI3-K pathways, and the contributions of PI3-K and ERK to signal chemotaxis varied with the concentrations of NGF used. In comparison, LY294002 treatment had no effect on ERK activation by EGF, but the chemotactic response was reduced at all the concentrations of EGF tested indicating that NGF and EGF differed in the utilization of ERK and PI3-K to signal chemotaxis in PC12 cells.

Attachment, invasion, chemotaxis, and proteinase expression of B16-BL6 melanoma cells exhibiting a low metastatic phenotype after exposure to dietary restriction of tyrosine and phenylalanine.

PubMed

Uhlenkott, C E; Huijzer, J C; Cardeiro, D J; Elstad, C A; Meadows, G G

1996-03-01

We previously reported that low levels of tyrosine (Tyr) and phenylalanine (Phe) alter the metastatic phenotype of B16-BL6 (BL6) murine melanoma and select for tumor cell populations with decreased lung colonizing ability. To more specifically characterize the effects of Tyr and Phe restriction on the malignant phenotype of BL6, we investigated in vitro attachment, invasion, proteinase expression, and chemotaxis of high and low metastatic BL6 variants. High metastatic variant cells were isolated from subcutaneous tumors of mice fed a nutritionally complete diet (ND cells) and low metastatic variant cells were isolated from mice fed a diet restricted in Tyr and Phe (LTP cells). Results indicate that attachment to reconstituted basement membrane (Matrigel) was significantly reduced in LTP cells as compared to ND cells. Attachment to collagen IV, laminin, and fibronectin were similar between the two variants. Invasion through Matrigel and growth factor-reduced Matrigel were significantly decreased in LTP cells as compared to ND cells. Zymography revealed the presence of M(r) 92,000 and M(r) 72,000 progelatinases, tissue plasminogen activator, and urokinase plasminogen activator in the conditioned medium of both variants; however, there were no differences in activity of these secreted proteinases between the two variants. Growth of the variants on growth factor-reduced Matrigel similarly induced expression of the M(r) 92,000 progelatinase. The variants exhibited similar chemotactic responses toward laminin. However, the chemotactic response toward fibronectin by LTP cells was significantly increased. MFR5, a monoclonal antibody which selectively blocks function of the alpha 5 chain of the alpha 5 beta 1 integrin, VLA-5, decreased the chemotactic response toward fibronectin of ND cells by 37%; the chemotactic response by LTP cells was reduced by 49%. This effect was specific for fibronectin-mediated chemotaxis since the chemotaxis toward laminin and invasion through Matrigel were not altered by the presence of MFR5. The surface expression of VLA-5 was significantly increased in LTP cells as compared to ND cells by flow cytometric analysis. These observations suggest that limitation of Tyr and Phe either directly modifies BL6 or selects for subpopulations with altered in vitro invasion, chemotaxis, and integrin expression.

Human umbilical cord blood stem cells show PDGF-D–dependent glioma cell tropism in vitro and in vivo

PubMed Central

Gondi, Christopher S.; Veeravalli, Krishna Kumar; Gorantla, Bharathi; Dinh, Dzung H.; Fassett, Dan; Klopfenstein, Jeffrey D.; Gujrati, Meena; Rao, Jasti S.

2010-01-01

Despite advances in clinical therapies and technologies, the prognosis for patients with malignant glioma is poor. Neural stem cells (NSCs) have a chemotactic tropism toward glioma cells. The use of NSCs as carriers of therapeutic agents for gliomas is currently being explored. Here, we demonstrate that cells isolated from the umbilical cord blood show mesenchymal characteristics and can differentiate to adipocytes, osteocytes, and neural cells and show tropism toward cancer cells. We also show that these stem cells derived from the human umbilical cord blood (hUCB) induce apoptosis-like cell death in the glioma cell line SNB19 via Fas-mediated caspase-8 activation. From our glioma tropism studies, we have observed that hUCB cells show tropism toward glioma cells in vitro, in vivo, and ex vivo. We determined that this migration is partially dependent on the expression levels of platelet-derived growth factor (PDGF)-D from glioma cells and have observed that local concentration gradient of PDGF-D is sufficient to cause migration of hUCB cells toward the gradient as seen from our brain slice cultures. In our animal experiment studies, we observed that intracranially implanted SNB19 green fluorescent protein cells induced tropism of the hUCB cells toward themselves. In addition, the ability of these hUCBs to inhibit established intracranial tumors was also observed. We also determined that the migration of stem cells toward glioma cells was partially dependent on PDGF secreted by glioma cells and that the presence of PDGF-receptor (PDGFR) on hUCB is required for migration. Our results demonstrate that hUCB are capable of inducing apoptosis in human glioma cells and also show that glioma tropism and hUCB tropism toward glioma cells are partially dependent on the PDGF/PGGFR system. PMID:20406896

A computational model for how cells choose temporal or spatial sensing during chemotaxis.

PubMed

Tan, Rui Zhen; Chiam, Keng-Hwee

2018-03-01

Cell size is thought to play an important role in choosing between temporal and spatial sensing in chemotaxis. Large cells are thought to use spatial sensing due to large chemical difference at its ends whereas small cells are incapable of spatial sensing due to rapid homogenization of proteins within the cell. However, small cells have been found to polarize and large cells like sperm cells undergo temporal sensing. Thus, it remains an open question what exactly governs spatial versus temporal sensing. Here, we identify the factors that determines sensing choices through mathematical modeling of chemotactic circuits. Comprehensive computational search of three-node signaling circuits has identified the negative integral feedback (NFB) and incoherent feedforward (IFF) circuits as capable of adaptation, an important property for chemotaxis. Cells are modeled as one-dimensional circular system consisting of diffusible activator, inactivator and output proteins, traveling across a chemical gradient. From our simulations, we find that sensing outcomes are similar for NFB or IFF circuits. Rather than cell size, the relevant parameters are the 1) ratio of cell speed to the product of cell diameter and rate of signaling, 2) diffusivity of the output protein and 3) ratio of the diffusivities of the activator to inactivator protein. Spatial sensing is favored when all three parameters are low. This corresponds to a cell moving slower than the time it takes for signaling to propagate across the cell diameter, has an output protein that is polarizable and has a local-excitation global-inhibition system to amplify the chemical gradient. Temporal sensing is favored otherwise. We also find that temporal sensing is more robust to noise. By performing extensive literature search, we find that our prediction agrees with observation in a wide range of species and cell types ranging from E. coli to human Fibroblast cells and propose that our result is universally applicable.

A computational model for how cells choose temporal or spatial sensing during chemotaxis

PubMed Central

Tan, Rui Zhen; Chiam, Keng-Hwee

2018-01-01

Cell size is thought to play an important role in choosing between temporal and spatial sensing in chemotaxis. Large cells are thought to use spatial sensing due to large chemical difference at its ends whereas small cells are incapable of spatial sensing due to rapid homogenization of proteins within the cell. However, small cells have been found to polarize and large cells like sperm cells undergo temporal sensing. Thus, it remains an open question what exactly governs spatial versus temporal sensing. Here, we identify the factors that determines sensing choices through mathematical modeling of chemotactic circuits. Comprehensive computational search of three-node signaling circuits has identified the negative integral feedback (NFB) and incoherent feedforward (IFF) circuits as capable of adaptation, an important property for chemotaxis. Cells are modeled as one-dimensional circular system consisting of diffusible activator, inactivator and output proteins, traveling across a chemical gradient. From our simulations, we find that sensing outcomes are similar for NFB or IFF circuits. Rather than cell size, the relevant parameters are the 1) ratio of cell speed to the product of cell diameter and rate of signaling, 2) diffusivity of the output protein and 3) ratio of the diffusivities of the activator to inactivator protein. Spatial sensing is favored when all three parameters are low. This corresponds to a cell moving slower than the time it takes for signaling to propagate across the cell diameter, has an output protein that is polarizable and has a local-excitation global-inhibition system to amplify the chemical gradient. Temporal sensing is favored otherwise. We also find that temporal sensing is more robust to noise. By performing extensive literature search, we find that our prediction agrees with observation in a wide range of species and cell types ranging from E. coli to human Fibroblast cells and propose that our result is universally applicable. PMID:29505572

DECREASED HEART RATE IS ASSOCIATED WITH CARBAMATE-INDUCED ACTIVATION OF PRO-INFLAMMATORY SERUM PROTEINS.

EPA Science Inventory

Previously we reported that chlorpyrifos (CHP), an irreversible cholinesterase (ChE) inhibitor, induces hypertension in rats. Concomitant with hypertension, we found an increase in C-reactive protein, macrophage inflammatory protein-2 , monocyte chemotactic protein-5 and interfer...

Processing of natural and recombinant CXCR3-targeting chemokines and implications for biological activity.

PubMed

Hensbergen, P J; van der Raaij-Helmer, E M; Dijkman, R; van der Schors, R C; Werner-Felmayer, G; Boorsma, D M; Scheper, R J; Willemze, R; Tensen, C P

2001-09-01

Chemokines comprise a class of peptides with chemotactic activity towards leukocytes. The potency of different chemokines for the same receptor often varies as a result of differences in primary structure. In addition, post-translational modifications have been shown to affect the effectiveness of chemokines. Although in several studies, natural CXCR3-targeting chemokines have been isolated, detailed information about the proteins and their possible modifications is lacking. Using a combination of liquid chromatography and mass spectrometry we studied the protein profile of CXCR3-targeting chemokines expressed by interferon-gamma-stimulated human keratinocytes. The biological implications of one of the identified modifications was studied in more detail using calcium mobilization and chemotaxis assays. We found that the primary structure of human CXCL10 is different from the generally accepted sequence. In addition we identified a C-terminally truncated CXCL10, lacking the last four amino acids. Native CXCL11 was primarily found in its intact mature form but we also found a mass corresponding to an N-terminally truncated human CXCL11, lacking the first two amino acids FP, indicating that this chemokine is a substrate for dipeptidylpeptidase IV. Interestingly, this same truncation was found when we expressed human CXCL11 in Drosophila S2 cells. The biological activity of this truncated form of CXCL11 was greatly reduced, both in calcium mobilization (using CXCR3 expressing CHO cells) as well as its chemotactic activity for CXCR3-expressing T-cells. It is concluded that detailed information on chemokines at the protein level is important to characterize the exact profile of these chemotactic peptides as modifications can severely alter their biological activity.

I-309/T cell activation gene-3 chemokine protects murine T cell lymphomas against dexamethasone-induced apoptosis.

PubMed

Van Snick, J; Houssiau, F; Proost, P; Van Damme, J; Renauld, J C

1996-09-15

We have previously reported that cytokines such as IL-9, IL-4, and IL-6 protect murine thymic lymphoma cell lines against dexamethasone-induced apoptosis. A similar activity, which could not be ascribed to any of these factors, was found in a number of human T cell supernatants that enabled mouse BW5147 thymic lymphoma not only to escape apoptosis but also to maintain proliferation. The protein responsible for this activity was purified to homogeneity from the culture medium of activated leukemic T cells and was found to be identical with the I-309 chemokine. Half-maximal anti-apoptotic activity was obtained with approximately 1 ng/ml, a concentration considerably lower than that required for the monocyte chemotactic activity of this molecule, as measured on THP-1 cells. The purified I-309 also improved the survival of two other mouse thymic lymphoma cell lines. This activity was as potent as that of IL-9, which was the strongest anti-apoptotic factor found to date for these cells. Similar results were obtained for BW5147 cells with recombinant I-309 and with T cell activation gene-3, the murine homologue of I-309, but not with other members of the chemokine family, including IL-8, neutrophil-activating peptide-2, granulocyte chemotactic protein-2, macrophage inflammatory protein-1a, RANTES (regulated upon activation, normal T cell expressed and secreted), monocyte chemotactic protein-1 (MCP-1), and MCP-2. MCP-3, however, showed a minor, but significant effect in this model. Unlike that of IL-9, the activity of I-309 was completely inhibited in the presence of pertussis toxin, indicating the involvement of a G protein in this process.

Renal Amyloidosis: Origin and Clinicopathologic Correlations of 474 Recent Cases

PubMed Central

Said, Samar M.; Sethi, Sanjeev; Valeri, Anthony M.; Leung, Nelson; Cornell, Lynn D.; Fidler, Mary E.; Herrera Hernandez, Loren; Vrana, Julie A.; Theis, Jason D.; Quint, Patrick S.; Dogan, Ahmet

2013-01-01

Summary Background and objectives The kidney is the organ most commonly involved in systemic amyloidosis. This study reports the largest clinicopathologic series of renal amyloidosis. Design, setting, participants, & measurements This study provides characteristics of 474 renal amyloidosis cases evaluated at the Mayo Clinic Renal Pathology Laboratory from 2007 to 2011, including age, sex, serum creatinine, proteinuria, type of amyloid, and tissue distribution according to type. Results The type of amyloid was Ig amyloidosis in 407 patients (85.9%), AA amyloidosis in 33 (7.0%), leukocyte chemotactic factor 2 amyloidosis in 13 (2.7%), fibrinogen A α chain amyloidosis in 6 (1.3%), Apo AI, Apo AII, or Apo AIV amyloidosis in 3 (0.6%), combined AA amyloidosis/Ig heavy and light chain amyloidosis in 1 (0.2%), and unclassified in 11 (2.3%). Laser microdissection/mass spectrometry, performed in 147 cases, was needed to determine the origin of amyloid in 74 of the 474 cases (16%), whereas immunofluorescence failed to diagnose 28 of 384 light chain amyloidosis cases (7.3%). Leukocyte chemotactic factor 2 amyloidosis and Apo AI, Apo AII, or Apo AIV amyloidosis were characterized by diffuse interstitial deposition, whereas fibrinogen A α chain amyloidosis showed obliterative glomerular involvement. Compared with other types, Ig amyloidosis was associated with lower serum creatinine, higher degree of proteinuria, and amyloid spicules. Conclusions In the authors’ experience, the vast majority of renal amyloidosis cases are Ig derived. The newly identified leukocyte chemotactic factor 2 amyloidosis form was the most common of the rarer causes of renal amyloidosis. With the advent of laser microdissection/mass spectrometry for amyloid typing, the origin of renal amyloidosis can be determined in >97% of cases. PMID:23704299

Natural Killer (NK)/melanoma cell interaction induces NK-mediated release of chemotactic High Mobility Group Box-1 (HMGB1) capable of amplifying NK cell recruitment

PubMed Central

Parodi, Monica; Pedrazzi, Marco; Cantoni, Claudia; Averna, Monica; Patrone, Mauro; Cavaletto, Maria; Spertino, Stefano; Pende, Daniela; Balsamo, Mirna; Pietra, Gabriella; Sivori, Simona; Carlomagno, Simona; Mingari, Maria Cristina; Moretta, Lorenzo; Sparatore, Bianca; Vitale, Massimo

2015-01-01

In this study we characterize a new mechanism by which Natural Killer (NK) cells may amplify their recruitment to tumors. We show that NK cells, upon interaction with melanoma cells, can release a chemotactic form of High Mobility Group Box-1 (HMGB1) protein capable of attracting additional activated NK cells. We first demonstrate that the engagement of different activating NK cell receptors, including those mainly involved in tumor cell recognition can induce the active release of HMGB1. Then we show that during NK-mediated tumor cell killing two HMGB1 forms are released, each displaying a specific electrophoretic mobility possibly corresponding to a different redox status. By the comparison of normal and perforin-defective NK cells (which are unable to kill target cells) we demonstrate that, in NK/melanoma cell co-cultures, NK cells specifically release an HMGB1 form that acts as chemoattractant, while dying tumor cells passively release a non-chemotactic HMGB1. Finally, we show that Receptor for Advanced Glycation End products is expressed by NK cells and mediates HMGB1-induced NK cell chemotaxis. Proteomic analysis of NK cells exposed to recombinant HMGB1 revealed that this molecule, besides inducing immediate chemotaxis, also promotes changes in the expression of proteins involved in the regulation of the cytoskeletal network. Importantly, these modifications could be associated with an increased motility of NK cells. Thus, our findings allow the definition of a previously unidentified mechanism used by NK cells to amplify their response to tumors, and provide additional clues for the emerging role of HMGB1 in immunomodulation and tumor immunity. PMID:26587323

Aromatic D-amino acids act as chemoattractant factors for human leukocytes through a G protein-coupled receptor, GPR109B.

PubMed

Irukayama-Tomobe, Yoko; Tanaka, Hirokazu; Yokomizo, Takehiko; Hashidate-Yoshida, Tomomi; Yanagisawa, Masashi; Sakurai, Takeshi

2009-03-10

GPR109B (HM74) is a putative G protein-coupled receptor (GPCR) whose cognate ligands have yet to be characterized. GPR109B shows a high degree of sequence similarity to GPR109A, another GPCR that was identified as a high-affinity nicotinic acid (niacin) receptor. However, the affinity of nicotinic acid to GPR109B is very low. In this study, we found that certain aromatic D-amino acids, including D-phenylalanine, D-tryptophan, and the metabolite of the latter, D-kynurenine, decreased the activity of adenylate cyclase in cells transfected with GPR109B cDNA through activation of pertussis toxin (PTX)-sensitive G proteins. These D-amino acids also elicited a transient rise of intracellular Ca(2+) level in cells expressing GPR109B in a PTX-sensitive manner. In contrast, these D-amino acids did not show any effects on cells expressing GPR109A. We found that the GPR109B mRNA is abundantly expressed in human neutrophils. D-phenylalanine and D-tryptophan induced a transient increase of intracellular Ca(2+) level and a reduction of cAMP levels in human neutrophils. Furthermore, knockdown of GPR109B by RNA interference inhibited the D-amino acids-induced decrease of cellular cAMP levels in human neutrophils. These D-amino acids induced chemotactic activity of freshly prepared human neutrophils. We also found that D-phenylalanine and D-tryptophan induced chemotactic responses in Jurkat cells transfected with the GPR109B cDNA but not in mock-transfected Jurkat cells. These results suggest that these aromatic D-amino acids elicit a chemotactic response in human neutrophils via activation of GPR109B.

Sperm chemotaxis in siphonophores. II. Calcium-dependent asymmetrical movement of spermatozoa induced by the attractant.

PubMed

Cosson, M P; Carré, D; Cosson, J

1984-06-01

Spermatozoa from siphonophores have been shown to be attracted towards an extracellular structure, the cupule, which covers the predetermined site of fertilization of the egg. Observations on sperm behaviour during the chemotactic response show that spermatozoa describe trajectories of large diameter (700-1000 micron) while far from the cupule, and of smaller diameter (200 micron) in the cupule area. The transition between the two types of swimming occurs progressively when spermatozoa cross a 3 mm wide area around the cupule. After a few minutes 99% of the spermatozoa keep swimming around the attractant source, following circular paths 150-200 micron in diameter. In the absence of the attractant, comparable modifications of sperm trajectories are observed in the presence of the ionophore A23187 and high calcium concentrations. In the presence of 10(-2) M calcium ions, A23187-treated spermatozoa describe trajectories 200 micron in diameter, which increase up to 800 micron at lower calcium concentrations (10(-6) M). In the absence of calcium ions, spermatozoa swim across the cupule area without modification of their trajectories and no sperm accumulation can be detected. This requirement of the chemotactic response for calcium ions is observed either with fresh cupules stuck on the eggs, with cupules separated from the eggs, or with cupule extracts. Moreover, a soluble component fractionated from the cupule induces, when diluted in sea water, a reduction in the size of the sperm trajectories and this also requires calcium ions. The present data show that the chemotactic response of siphonophore sperm, which requires millimolar concentrations of calcium ions, occurs through a non-transient induction of increased asymmetry of the flagellar waveform. It is proposed that the natural attractant operates to produce an increase in the intraaxonemal calcium concentration.

MHC Class II Activation and Interferon-γ Mediate the Inhibition of Neutrophils and Eosinophils by Staphylococcal Enterotoxin Type A (SEA).

PubMed

Ferreira-Duarte, Ana P; Pinheiro-Torres, Anelize S; Anhê, Gabriel F; Condino-Neto, Antônio; Antunes, Edson; DeSouza, Ivani A

2017-01-01

Staphylococcal enterotoxins are classified as superantigens that act by linking T-cell receptor with MHC class II molecules, which are expressed on classical antigen-presenting cells (APC). Evidence shows that MHC class II is also expressed in neutrophils and eosinophils. This study aimed to investigate the role of MHC class II and IFN-γ on chemotactic and adhesion properties of neutrophils and eosinophils after incubation with SEA. Bone marrow (BM) cells obtained from BALB/c mice were resuspended in culture medium, and incubated with SEA (3-30 ng/ml; 1-4 h), after which chemotaxis and adhesion were evaluated. Incubation with SEA significantly reduced the chemotactic and adhesive responses in BM neutrophils activated with IL-8 (200 ng/ml). Likewise, SEA significantly reduced the chemotactic and adhesive responses of BM eosinophils activated with eotaxin (300 ng/ml). The inhibitory effects of SEA on cell chemotaxis and adhesion were fully prevented by prior incubation with an anti-MHC class II blocking antibody (2 μg/ml). SEA also significantly reduced the intracellular Ca 2+ levels in IL-8- and eotaxin-activated BM cells. No alterations of MAC-1, VLA4, and LFA-1α expressions were observed after SEA incubation. In addition, SEA elevated by 3.5-fold ( P < 0.05) the INF-γ levels in BM cells. Incubation of BM leukocytes with IFN-γ (10 ng/ml, 2 h) reduced both neutrophil and eosinophil chemotaxis and adhesion, which were prevented by prior incubation with anti-MHC class II antibody (2 μg/ml). In conclusion, SEA inhibits neutrophil and eosinophil by MHC class II-dependent mechanism, which may be modulated by concomitant release of IFN-γ.

Effect of fluticasone propionate on neutrophil chemotaxis, superoxide generation, and extracellular proteolytic activity in vitro.

PubMed Central

Llewellyn-Jones, C. G.; Hill, S. L.; Stockley, R. A.

1994-01-01

BACKGROUND--Corticosteroids are widely used in the treatment of many inflammatory conditions but the exact mode of action on neutrophil function is uncertain. Fluticasone propionate is a new topically active synthetic steroid which can be measured in body fluids and which undergoes first pass metabolism. METHODS--The effects of fluticasone propionate on the function of neutrophils isolated from normal, healthy control subjects and on the chemotactic activity of sputum sol phase were assessed. RESULTS--Preincubation of neutrophils with fluticasone propionate reduced the chemotactic response to 10(-8) mol/l F-Met-Leu-Phe (FMLP) and to a 1:5 dilution of sputum sol phase in a dose dependent manner. Furthermore, when fluticasone propionate was added to sputum from eight patients with stable chronic obstructive bronchitis the chemotactic activity of a 1:5 dilution of the sol phase fell from a mean (SE) value of 22.2 (1.21) cells/field to 19.6 (0.89), 17.1 (0.74), and 11.9 (0.6) cells field at 1 mumol/l, 10 mumol/l, and 100 mumol/l, respectively. In further experiments fluticasone propionate preincubated with neutrophils inhibited fibronectin degradation by resting cells and by cells stimulated by FMLP (15.2% inhibition of resting cells, 5.1% inhibition of stimulated cells with 1 mumol/l fluticasone propionate, 24% and 18.7% inhibition respectively at 100 mumol/l fluticasone propionate. Fluticasone propionate had no effect on generation of superoxide anion by resting or stimulated cells. CONCLUSIONS--These results indicate that fluticasone propionate has a direct suppressive effect on several aspects of neutrophil function and may suggest a role for this agent in the modulation of neutrophil mediated damage to connective tissue. PMID:8202875

Effect of fluticasone propionate on neutrophil chemotaxis, superoxide generation, and extracellular proteolytic activity in vitro.

PubMed

Llewellyn-Jones, C G; Hill, S L; Stockley, R A

1994-03-01

Corticosteroids are widely used in the treatment of many inflammatory conditions but the exact mode of action on neutrophil function is uncertain. Fluticasone propionate is a new topically active synthetic steroid which can be measured in body fluids and which undergoes first pass metabolism. The effects of fluticasone propionate on the function of neutrophils isolated from normal, healthy control subjects and on the chemotactic activity of sputum sol phase were assessed. Preincubation of neutrophils with fluticasone propionate reduced the chemotactic response to 10(-8) mol/l F-Met-Leu-Phe (FMLP) and to a 1:5 dilution of sputum sol phase in a dose dependent manner. Furthermore, when fluticasone propionate was added to sputum from eight patients with stable chronic obstructive bronchitis the chemotactic activity of a 1:5 dilution of the sol phase fell from a mean (SE) value of 22.2 (1.21) cells/field to 19.6 (0.89), 17.1 (0.74), and 11.9 (0.6) cells field at 1 mumol/l, 10 mumol/l, and 100 mumol/l, respectively. In further experiments fluticasone propionate preincubated with neutrophils inhibited fibronectin degradation by resting cells and by cells stimulated by FMLP (15.2% inhibition of resting cells, 5.1% inhibition of stimulated cells with 1 mumol/l fluticasone propionate, 24% and 18.7% inhibition respectively at 100 mumol/l fluticasone propionate. Fluticasone propionate had no effect on generation of superoxide anion by resting or stimulated cells. These results indicate that fluticasone propionate has a direct suppressive effect on several aspects of neutrophil function and may suggest a role for this agent in the modulation of neutrophil mediated damage to connective tissue.

Effect of fluticasone propionate on sputum of patients with chronic bronchitis and emphysema.

PubMed

Llewellyn-Jones, C G; Harris, T A; Stockley, R A

1996-02-01

The effects of fluticasone propionate (FP) on sputum chemotactic activity, elastase inhibitory potential, albumin concentrations, and peripheral neutrophil function were studied in a group of patients with clinically stable, smoking-related chronic bronchitis and emphysema. Seventeen patients (50 to 75 yr of age) were entered into a double-blind, placebo-controlled study of 1.5 mg inhaled FP/d for 8 wk. Following treatment with FP the chemotactic activity of the sputum sol phase was lower than the corresponding values for the placebo group (p < 0.01). Values fell from a mean of 21.75 (+/- 1.58) during the run-in period to 18.37 (+/- 1.46; p < 0.01) after 4 wk and 17.63 (+/- 1.86; p < 0.05) after 8 wk treatment returning to 22.08 (+/- 1.26) cell/field after the washout period. The neutrophil elastase inhibitory capacity of the sputum sol phase increased (p < 0.025) with treatment from a mean of 0.177 microM elastase inhibited/L (+/- 0.05) pretreatment to 0.413 microM (+/- 0.054) after 4 wk and 0.415 microM (+/- 0.054) after 8 wk returning to 0.270 microM (+/- 0.07) after the washout period. Treatment with FP did not result in a change in the peripheral neutrophil functions studied or sputum albumin and myeloperoxidase concentrations. The results suggest that FP may play a protective role in these patients through a reduction in the chemotactic activity of lung secretions and potentially a reduction in the recruitment of neutrophils to the lung, and also by directly affecting the proteinase/antiproteinase balance, in favor of antiproteinases, within lung secretions.

Statistical signatures of a targeted search by bacteria

NASA Astrophysics Data System (ADS)

Jashnsaz, Hossein; Anderson, Gregory G.; Pressé, Steve

2017-12-01

Chemoattractant gradients are rarely well-controlled in nature and recent attention has turned to bacterial chemotaxis toward typical bacterial food sources such as food patches or even bacterial prey. In environments with localized food sources reminiscent of a bacterium’s natural habitat, striking phenomena—such as the volcano effect or banding—have been predicted or expected to emerge from chemotactic models. However, in practice, from limited bacterial trajectory data it is difficult to distinguish targeted searches from an untargeted search strategy for food sources. Here we use a theoretical model to identify statistical signatures of a targeted search toward point food sources, such as prey. Our model is constructed on the basis that bacteria use temporal comparisons to bias their random walk, exhibit finite memory and are subject to random (Brownian) motion as well as signaling noise. The advantage with using a stochastic model-based approach is that a stochastic model may be parametrized from individual stochastic bacterial trajectories but may then be used to generate a very large number of simulated trajectories to explore average behaviors obtained from stochastic search strategies. For example, our model predicts that a bacterium’s diffusion coefficient increases as it approaches the point source and that, in the presence of multiple sources, bacteria may take substantially longer to locate their first source giving the impression of an untargeted search strategy.

Physical phenomena and the microgravity response

NASA Technical Reports Server (NTRS)

Todd, Paul

1989-01-01

The living biological cell is not a sack of Newtonian fluid containing systems of chemical reactions at equilibrium. It is a kinetically driven system, not a thermodynamically driven system. While the cell as a whole might be considered isothermal, at the scale of individual macromolecular events there is heat generated, and presumably sharp thermal gradients exist at the submicron level. Basic physical phenomena to be considered when exploring the cell's response to inertial acceleration include particle sedimentation, solutal convection, motility electrokinetics, cytoskeletal work, and hydrostatic pressure. Protein crystal growth experiments, for example, illustrate the profound effects of convection currents on macromolecular assembly. Reaction kinetics in the cell vary all the way from diffusion-limited to life-time limited. Transport processes vary from free diffusion, to facilitated and active transmembrane transport, to contractile-protein-driven motility, to crystalline immobilization. At least four physical states of matter exist in the cell: aqueous, non-aqueous, immiscible-aqueous, and solid. Levels of order vary from crystalline to free solution. The relative volumes of these states profoundly influence the cell's response to inertial acceleration. Such subcellular phenomena as stretch-receptor activation, microtubule re-assembly, synaptic junction formation, chemotactic receptor activation, and statolith sedimentation were studied recently with respect to both their basic mechanisms and their responsiveness to inertial acceleration. From such studies a widespread role of cytoskeletal organization is becoming apparent.

Pseudomonas putida F1 uses energy taxis to sense hydroxycinnamic acids

PubMed Central

Hughes, Jonathan G.; Zhang, Xiangsheng; Parales, Juanito V.; Ditty, Jayna L.; Parales, Rebecca E.

2017-01-01

Soil bacteria such as pseudomonads are widely studied due to their diverse metabolic capabilities, particularly the ability to degrade both naturally occurring and xenobiotic aromatic compounds. Chemotaxis, the directed movement of cells in response to chemical gradients, is common in motile soil bacteria and the wide range of chemicals detected often mirrors the metabolic diversity observed. Pseudomonas putida F1 is a soil isolate capable of chemotaxis toward, and degradation of, numerous aromatic compounds. We showed that P. putida F1 is capable of degrading members of a class of naturally occurring aromatic compounds known as hydroxycinnamic acids, which are components of lignin and are ubiquitous in the soil environment. We also demonstrated the ability of P. putida F1 to sense three hydroxycinnamic acids: p-coumaric, caffeic and ferulic acids. The chemotaxis response to hydroxycinnamic acids was induced during growth in the presence of hydroxycinnamic acids and was negatively regulated by HcaR, the repressor of the hydroxycinnamic acid catabolic genes. Chemotaxis to the three hydroxycinnamic acids was dependent on catabolism, as a mutant lacking the gene encoding feruloyl-CoA synthetase (Fcs), which catalyzes the first step in hydroxycinnamic acid degradation, was unable to respond chemotactically toward p-coumaric, caffeic, or ferulic acids. We tested whether an energy taxis mutant could detect hydroxycinnamic acids and determined that hydroxycinnamic acid sensing is mediated by the energy taxis receptor Aer2. PMID:28954643

Intravital imaging of CTLs killing islet cells in diabetic mice

PubMed Central

Coppieters, Ken; Amirian, Natalie; von Herrath, Matthias

2011-01-01

Type 1 diabetes (T1D) is caused by autoimmune destruction of the insulin-producing β cells in the pancreatic islets, which are essentially mini-organs embedded in exocrine tissue. CTLs are considered to have a predominant role in the autoimmune destruction underlying T1D. Visualization of CTL-mediated killing of β cells would provide new insight into the pathogenesis of T1D, but has been technically challenging to achieve. Here, we report our use of intravital 2-photon imaging in mice to visualize the dynamic behavior of a virally expanded, diabetogenic CTL population in the pancreas at cellular resolution. Following vascular arrest and extravasation, CTLs adopted a random motility pattern throughout the compact exocrine tissue and displayed unimpeded yet nonlinear migration between anatomically nearby islets. Upon antigen encounter within islets, a confined motility pattern was acquired that allowed the CTLs to scan the target cell surface. A minority of infiltrating CTLs subsequently arrested at the β cell junction, while duration of stable CTL–target cell contact was on the order of hours. Slow-rate killing occurred in the sustained local presence of substantial numbers of effector cells. Collectively, these data portray the kinetics of CTL homing to and between antigenic target sites as a stochastic process at the sub-organ level and argue against a dominant influence of chemotactic gradients. PMID:22133877

Adult subependymal neural precursors, but not differentiated cells, undergo rapid cathodal migration in the presence of direct current electric fields.

PubMed

Babona-Pilipos, Robart; Droujinine, Ilia A; Popovic, Milos R; Morshead, Cindi M

2011-01-01

The existence of neural stem and progenitor cells (together termed neural precursor cells) in the adult mammalian brain has sparked great interest in utilizing these cells for regenerative medicine strategies. Endogenous neural precursors within the adult forebrain subependyma can be activated following injury, resulting in their proliferation and migration toward lesion sites where they differentiate into neural cells. The administration of growth factors and immunomodulatory agents following injury augments this activation and has been shown to result in behavioural functional recovery following stroke. With the goal of enhancing neural precursor migration to facilitate the repair process we report that externally applied direct current electric fields induce rapid and directed cathodal migration of pure populations of undifferentiated adult subependyma-derived neural precursors. Using time-lapse imaging microscopy in vitro we performed an extensive single-cell kinematic analysis demonstrating that this galvanotactic phenomenon is a feature of undifferentiated precursors, and not differentiated phenotypes. Moreover, we have shown that the migratory response of the neural precursors is a direct effect of the electric field and not due to chemotactic gradients. We also identified that epidermal growth factor receptor (EGFR) signaling plays a role in the galvanotactic response as blocking EGFR significantly attenuates the migratory behaviour. These findings suggest direct current electric fields may be implemented in endogenous repair paradigms to promote migration and tissue repair following neurotrauma.

Chemotactic selection of pollutant degrading soil bacteria

DOEpatents

Hazen, Terry C.

1994-01-01

A method for identifying soil microbial strains which may be bacterial degraders of pollutants comprising the steps of placing a concentration of a pollutant in a substantially closed container, placing the container in a sample of soil for a period of time ranging from one minute to several hours, retrieving the container, collecting the contents of the container, and microscopically determining the identity of the bacteria present. Different concentrations of the pollutant can be used to determine which bacteria respond to each concentration. The method can be used for characterizing a polluted site or for looking for naturally occurring biological degraders of the pollutant. Then bacteria identified as degraders of the pollutant and as chemotactically attracted to the pollutant are used to inoculate contaminated soil. To enhance the effect of the bacteria on the pollutant, nutrients are cyclicly provided to the bacteria then withheld to alternately build up the size of the bacterial colony or community and then allow it to degrade the pollutant.

Chemotactic selection of pollutant degrading soil bacteria

DOEpatents

Hazen, T.C.

1991-03-04

A method is described for identifying soil microbial strains which may be bacterial degraders of pollutants. This method includes: Placing a concentration of a pollutant in a substantially closed container; placing the container in a sample of soil for a period of time ranging from one minute to several hours; retrieving the container and collecting its contents; microscopically determining the identity of the bacteria present. Different concentrations of the pollutant can be used to determine which bacteria respond to each concentration. The method can be used for characterizing a polluted site or for looking for naturally occurring biological degraders of the pollutant. Then bacteria identified as degraders of the pollutant and as chemotactically attracted to the pollutant are used to innoculate contaminated soil. To enhance the effect of the bacteria on the pollutant, nutrients are cyclicly provided to the bacteria then withheld to alternately build up the size of the bacterial colony or community and then allow it to degrade the pollutant.

Adaptability of non-genetic diversity in bacterial chemotaxis

PubMed Central

Frankel, Nicholas W; Pontius, William; Dufour, Yann S; Long, Junjiajia; Hernandez-Nunez, Luis; Emonet, Thierry

2014-01-01

Bacterial chemotaxis systems are as diverse as the environments that bacteria inhabit, but how much environmental variation can cells tolerate with a single system? Diversification of a single chemotaxis system could serve as an alternative, or even evolutionary stepping-stone, to switching between multiple systems. We hypothesized that mutations in gene regulation could lead to heritable control of chemotactic diversity. By simulating foraging and colonization of E. coli using a single-cell chemotaxis model, we found that different environments selected for different behaviors. The resulting trade-offs show that populations facing diverse environments would ideally diversify behaviors when time for navigation is limited. We show that advantageous diversity can arise from changes in the distribution of protein levels among individuals, which could occur through mutations in gene regulation. We propose experiments to test our prediction that chemotactic diversity in a clonal population could be a selectable trait that enables adaptation to environmental variability. DOI: http://dx.doi.org/10.7554/eLife.03526.001 PMID:25279698

Mucorales species activation of a serum leukotactic factor.

PubMed Central

Marx, R S; Forsyth, K R; Hentz, S K

1982-01-01

Previous studies have suggested that the focal accumulation of phagocytic leukocytes is an important feature of the host response in mucormycosis. To ascertain the basis for this influx of inflammatory cells, we evaluated the effect of members of the order Mucorales, including species from the genera Rhizopus, Absidia, and Mucor, on the chemotactic activity of normal human serum for neutrophils and monocytes. Both hyphae and spores produced concentration-dependent chemotaxigenesis in serum to a maximum level equivalent to that produced by zymosan activation of serum. Chemotactic activity was similar for live and heat-killed hyphae. No leukotactic activity was demonstrated in the absence of serum. The pretreatment of serum with anti-C3 antibody, heating at 56 degrees C, or 0.01 M EDTA abolished the activity. The pretreatment of serum with 0.01 M ethylene glycol-bis(beta-aminoethyl ether)-N,N-tetraacetic acid did not abolish the activity. These data provide evidence that the leukotactic activity of Mucorales species is generated through the alternative complement pathway. PMID:6759409

The development of human mast cells. An historical reappraisal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ribatti, Domenico, E-mail: domenico.ribatti@uniba.it

2016-03-15

The understanding of mast cell (MC) differentiation is derived mainly from in vitro studies of different stages of stem and progenitor cells. The hematopoietic lineage development of human MCs is unique compared to other myeloid-derived cells. Human MCs originate from CD34{sup +}/CD117{sup +}/CD13{sup +}multipotent hematopoietic progenitors, which undergo transendothelial recruitment into peripheral tissues, where they complete differentiation. Stem cell factor (SCF) is a major chemotactic factor for MCs and their progenitors. SCF also elicits cell-cell and cell-substratum adhesion, facilitates the proliferation, and sustains the survival, differentiation, and maturation, of MCs. Because MC maturation is influenced by local microenvironmental factors, differentmore » MC phenotypes can develop in different tissues and organs. - Highlights: • Human mast cells originate from CD34/CD117/CD13 positive multipotent hematopoietic progenitors. • Stem cell factor is a major chemotactic factor for mast cells and their progenitors. • Different mast cell phenotypes can develop in different tissues and organs.« less

Monocyte Chemotactic Protein 1 in Plasma from Soluble Leishmania Antigen-Stimulated Whole Blood as a Potential Biomarker of the Cellular Immune Response to Leishmania infantum

PubMed Central

Ibarra-Meneses, Ana V.; Sanchez, Carmen; Alvar, Jorge; Moreno, Javier; Carrillo, Eugenia

2017-01-01

New biomarkers are needed to identify asymptomatic Leishmania infection as well as immunity following vaccination or treatment. With the aim of finding a robust biomarker to assess an effective cellular immune response, monocyte chemotactic protein 1 (MCP-1) was examined in plasma from soluble Leishmania antigen (SLA)-stimulated whole blood collected from subjects living in a Leishmania infantum-endemic area. MCP-1, expressed 110 times more strongly than IL-2, identified 87.5% of asymptomatic subjects and verified some asymptomatic subjects close to the cutoff. MCP-1 was also significantly elevated in all patients cured of visceral leishmaniasis (VL), unlike IL-2, indicating the specific memory response generated against Leishmania. These results show MCP-1 to be a robust candidate biomarker of immunity that could be used as a marker of cure and to both select and follow the population in vaccine phase I–III human clinical trials with developed rapid, easy-to-use field tools. PMID:29033933

Calaxin drives sperm chemotaxis by Ca2+-mediated direct modulation of a dynein motor

PubMed Central

Mizuno, Katsutoshi; Shiba, Kogiku; Okai, Masahiko; Takahashi, Yusuke; Shitaka, Yuji; Oiwa, Kazuhiro; Tanokura, Masaru; Inaba, Kazuo

2012-01-01

Sperm chemotaxis occurs widely in animals and plants and plays an important role in the success of fertilization. Several studies have recently demonstrated that Ca2+ influx through specific Ca2+ channels is a prerequisite for sperm chemotactic movement. However, the regulator that modulates flagellar movement in response to Ca2+ is unknown. Here we show that a neuronal calcium sensor, calaxin, directly acts on outer-arm dynein and regulates specific flagellar movement during sperm chemotaxis. Calaxin inhibition resulted in significant loss of sperm chemotactic movement, despite normal increases in intracellular calcium concentration. Using a demembranated sperm model, we demonstrate that calaxin is essential for generation and propagation of Ca2+-induced asymmetric flagellar bending. An in vitro motility assay revealed that calaxin directly suppressed the velocity of microtubule sliding by outer-arm dynein at high Ca2+ concentrations. This study describes the missing link between chemoattractant-mediated Ca2+ signaling and motor-driven microtubule sliding during sperm chemotaxis. PMID:23169663

Prevalence and organ distribution of leukocyte chemotactic factor 2 amyloidosis (ALECT2) among decedents in New Mexico.

PubMed

Larsen, Christopher P; Beggs, Marjorie L; Wilson, Jon D; Lathrop, Sarah L

2016-06-01

Leukocyte chemotactic factor 2 (LECT2) amyloidosis is one of the most recently described types of amyloidosis. Since its description, it has been found to be one the most common types of amyloidosis in large series of amyloid cases involving the kidney and liver in the United States, where it primarily affects patients of Hispanic ethnicity. We sought to investigate the prevalence of this disease among Hispanic adult decedents who had an autopsy performed at the New Mexico Office of the Medical Investigator and determine the organ distribution of amyloid deposition. LECT2 amyloid deposits were identified within the kidney in 3.1% of Hispanic decedents. It was consistently deposited in the liver, spleen, adrenals, and lungs but did not involve the myocardium or brain. LECT2 amyloidosis is likely not rare among Hispanics in the Southwest United States and could represent an important but under-recognized etiology of chronic kidney disease in this population.

Statins Inhibit Monocyte Chemotactic Protein 1 Expression in Endometriosis

PubMed Central

Cakmak, Hakan; Basar, Murat; Seval-Celik, Yasemin; Osteen, Kevin G.; Duleba, Antoni J.; Taylor, Hugh S.; Lockwood, Charles J.; Arici, Aydin

2012-01-01

Statins are potent inhibitors of the endogenous mevalonate pathway. Besides inhibiting cholesterol biosynthesis, statins may also demonstrate anti-inflammatory properties. Inflammation is implicated in the attachment and invasion of endometrial cells to the peritoneal surface and growth of ectopic endometrium by inducing proliferation and angiogenesis. In this study, the effect of statins on monocyte chemotactic protein 1 (MCP-1) expression in endometriotic implants in nude mouse model and in cultured endometriotic cells was evaluated. In mouse model, simvastatin decreased MCP-1 expression in a dose-dependent manner in endometriotic implants (P < .05). Similarly, both simvastatin and mevastatin revealed a dose-dependent inhibition of MCP-1 production in cultured endometriotic cells (P < .01). This inhibitory effect of the statins on MCP-1 production was reversed by the downstream substrates of the mevalonate pathway. Moreover, statins decreased MCP-1 messenger RNA expression in cultured endometriotic cells (P < .05). In conclusion, statins exert anti-inflammatory effect in endometriotic cells and could provide a potential treatment of endometriosis in the future. PMID:22267540

Molecular strain typing of Brucella abortus isolates from Italy by two VNTR allele sizing technologies.

PubMed

De Santis, Riccardo; Ancora, Massimo; De Massis, Fabrizio; Ciammaruconi, Andrea; Zilli, Katiuscia; Di Giannatale, Elisabetta; Pittiglio, Valentina; Fillo, Silvia; Lista, Florigio

2013-10-01

Brucellosis, one of the most important re-emerging zoonoses in many countries, is caused by bacteria belonging to the genus Brucella. Furthermore these bacteria represent potential biological warfare agents and the identification of species and biovars of field strains may be crucial for tracing back source of infection, allowing to discriminate naturally occurring outbreaks instead of bioterrorist events. In the last years, multiple-locus variable-number tandem repeat analysis (MLVA) has been proposed as complement of the classical biotyping methods and it has been applied for genotyping large collections of Brucella spp. At present, the MLVA band profiles may be resolved by automated or manual procedures. The Lab on a chip technology represents a valid alternative to standard genotyping techniques (as agarose gel electrophoresis) and it has been previously used for Brucella genotyping. Recently, a new high-throughput genotyping analysis system based on capillary gel electrophoresis, the QIAxcel, has been described. The aim of the study was to evaluate the ability of two DNA sizing equipments, the QIAxcel System and the Lab chip GX, to correctly call alleles at the sixteen loci including one frequently used MLVA assay for Brucella genotyping. The results confirmed that these technologies represent a meaningful advancement in high-throughput Brucella genotyping. Considering the accuracy required to confidently resolve loci discrimination, QIAxcel shows a better ability to measure VNTR allele sizes compared to LabChip GX.

UGT2B17 and SULT1A1 gene copy number variation (CNV) detection by LabChip microfluidic technology.

PubMed

Gaedigk, Andrea; Gaedigk, Roger; Leeder, J Steven

2010-05-01

Gene copy number variations (CNVs) are increasingly recognized to play important roles in the expression of genes and hence on their respective enzymatic activities. This has been demonstrated for a number of drug metabolizing genes, such as UDP-glucuronosyltransferases 2B17 (UGT2B17) and sulfotransferase 1A1 (SULT1A1), which are subject to genetic heterogeneity, including CNV. Quantitative assays to assess gene copy number are therefore becoming an integral part of accurate genotype assessment and phenotype prediction. In this study, we evaluated a microfluidics-based system, the Bio-Rad Experion system, to determine the power and utility of this platform to detect UGT2B17 and SULT1A1 CNV in DNA samples derived from blood and tissue. UGT2B17 is known to present with 0, 1 or 2 and SULT1A1 with up to 5 gene copies. Distinct clustering (p<0.001) into copy number groups was achieved for both genes. DNA samples derived from blood exhibited less inter-run variability compared to DNA samples obtained from liver tissue. This variability may be caused by tissue-specific PCR inhibitors as it could be overcome by using DNA from another tissue, or after the DNA had undergone whole genome amplification. This method produced results comparable to those reported for other quantitative test platforms.

Neutrophil chemotaxis in response to TGF-beta isoforms (TGF-beta 1, TGF-beta 2, TGF-beta 3) is mediated by fibronectin.

PubMed

Parekh, T; Saxena, B; Reibman, J; Cronstein, B N; Gold, L I

1994-03-01

TGF-beta isoforms regulate numerous cellular functions including cell growth and differentiation, the cellular synthesis and secretion of extracellular matrix proteins, such as fibronectin (Fn), and the immune response. We have previously shown that TGF-beta 1 is the most potent chemoattractant described for human peripheral blood neutrophils (PMNs), suggesting that TGF-beta s may play a role in the recruitment of PMNs during the initial phase of the inflammatory response. In our current studies, we demonstrate that the maximal chemotactic response was attained near 40 fM for all mammalian TGF-beta isoforms. However, there was a statistically significant difference in migratory distance of the PMNs: TGF-beta 2 (556 microM) > TGF-beta 3 (463 microM) > TGF-beta 1 (380 microM) (beta 2: beta 3, p < or = 0.010; beta 3: beta 1, p < or = 0.04; beta 2: beta 1, p < or = 0.0012). A mAb to the cell binding domain (CBD) of Fn inhibited the chemotactic response to TGF-beta 1 and TGF-beta 3 by 63% and to TGF-beta 2 by 70%, whereas the response to FMLP, a classic chemoattractant, was only inhibited by 18%. In contrast, a mAb to a C-terminal epitope of Fn did not retard migration (< 1.5%). The Arg-gly-Asp-ser tetrapeptide inhibited chemotaxis by approximately the same extent as the anti-CBD (52 to 83%). Furthermore, a mAb against the VLA-5 integrin (VLA-5; Fn receptor) also inhibited TGF-beta-induced chemotaxis. These results indicate that chemotaxis of PMNs in response to TGF-beta isoforms is mediated by the interaction of the Arg-gly-Asp-ser sequence in the CBD of Fn with an integrin on the PMN cell surface, primarily the VLA-5 integrin. TGF-beta isoforms also elicited the release of cellular Fn from PMNs; we observed a 2.3-fold increase in Fn (389 to 401 ng/ml) in the supernatants of TGF-beta-stimulated PMNs compared with unstimulated cells (173.6 ng/ml). The concentration of TGF-beta required to cause maximal release of Fn from PMNs (4000 fM) is a concentration at which TGF-beta is no longer chemotactic, suggesting that PMNs only use Fn that is constitutively expressed for migration. At higher concentrations of TGF-beta, the Fn released may accumulate basal to the cell, ultimately retarding cellular migration and modulating the chemotactic response.

CHEMOTACTIC ROLE OF NEUROTROPIN 3 IN THE EMBRYONIC TESTIS THAT FACILITATES MORPHOLOGICAL MALE SEX DETERMINATION. (R827405)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Characterization and Reactivity of Broiler Chicken Sera to Selected Recombinant Campylobacter jejuni Chemotactic Proteins

USDA-ARS?s Scientific Manuscript database

Campylobacter jejuni, a Gram-negative rod bacterium, is the leading causative agent of human acute bacterial gastroenteritis worldwide. Consumption and handling of raw or undercooked poultry are regarded as a major source for human infection. Because bacterial chemotaxis guides microorganisms to c...

THE EFFECTS OF COMBINATORIAL EXPOSURE OF PRO-INFLAMMATORY AND ANTI-INFLAMMATORY CYTOKINES ON AIRWAY EPITHELIAL CELL RELEASE OF CHEMOTACTIC MEDIATORS

EPA Science Inventory

Asthma is a chronic inflammatory disorder of the airways affecting nearly 15 million individuals nationally. Within the inflamed asthmatic airway there exist complex interactions between many cells and the cytokines they release, in particular mast cells, eosinophils, T-lymphocy...

ARSENITE ACTIVATES KB-DEPENDENT IL-8 GENE EXPRESSION IN AIRWAY EPITHELIM IN THE ABSENCE OF NUCLEAR TRANSLOCATION OF NF-KB

EPA Science Inventory

Airway epithelial cells respond to certain environmental stresses by mounting a proinflammatory response, which is characterized by enhanced synthesis and release of the neutrophil chemotactic and activating factor interleukin-8 (IL-8). IL-8 expression is regulated at the transcr...

Increased monocyte chemotactic protein-1 concentration and monocyte count independently associate with a poor prognosis in dogs with lymphoma.

PubMed

Perry, J A; Thamm, D H; Eickhoff, J; Avery, A C; Dow, S W

2011-03-01

Overexpression of the chemokine monocyte chemotactic protein-1 (MCP-1) has been associated with a poor prognosis in many human cancers. Increased MCP-1 concentrations may promote tumour progression by increasing mobilization of myeloid derived suppressor cells such as immature monocytes and neutrophils. We hypothesized that increased numbers of peripheral neutrophils or monocytes and increased MCP-1 concentrations would predict a worse outcome in dogs with multicentric lymphoma. In this retrospective study involving 26 client-owned dogs diagnosed with lymphoma, we show that peripheral neutrophil and monocyte counts as well as serum MCP-1 concentrations were significantly elevated relative to healthy control animals, and that such increases were associated with a decreased disease-free interval in dogs treated with chemotherapy based on cyclophosphamide, vincristine, doxorubicin and prednisone (CHOP). To our knowledge, this is the first study showing that pretreatment evaluation of monocyte and neutrophil counts can provide important prognostic information in dogs with lymphoma. The mechanisms underlying these observations remain to be determined. © 2010 Blackwell Publishing Ltd.

Lytic and Chemotactic Features of the Plaque-Forming Bacterium KD531 on Phaeodactylum tricornutum

PubMed Central

Chen, Zhangran; Zheng, Wei; Yang, Luxi; Boughner, Lisa A.; Tian, Yun; Zheng, Tianling; Xu, Hong

2017-01-01

Phaeodactylum tricornutum is a dominant bloom forming species and potential biofuel feedstock. To control P. tricornutum bloom or to release lipids from P. tricornutum, we previously screened and identified the lytic bacterium Labrenzia sp. KD531 toward P. tricornutum. In the present study, we evaluated the lytic activity of Labrenzia sp. KD531 on microalgae and investigated its lytic mechanism. The results indicated that the lytic activity of KD531 was temperature- and pH-dependent, but light-independent. In addition to P. tricornutum, KD531 also showed lytic activity against other algal species, especially green algae. A quantitative analysis of algal cellular protein, carbohydrate and lipid content together with measurements of dry weight after exposure to bacteria-infected algal lysate indicated that the bacterium KD531 influenced the algal biomass by disrupting the algal cells. Both chemotactic analysis and microscopic observations of subsamples from different regions of formed plaques showed that KD531 could move toward and then directly contact algal cells. Direct contact between P. tricornutum and KD531 cells was essential for the lytic process. PMID:29312256

SU-8 based microdevices to study self-induced chemotaxis in 3D microenvironments

NASA Astrophysics Data System (ADS)

Ayuso, Jose; Monge, Rosa; Llamazares, Guillermo; Moreno, Marco; Agirregabiria, Maria; Berganzo, Javier; Doblaré, Manuel; Ochoa, Iñaki; Fernandez, Luis

2015-05-01

Tissues are complex three-dimensional structures in which cell behaviour is frequently guided by chemotactic signals. Although starvation and nutrient restriction induce many different chemotactic processes, the recreation of such conditions in vitro remains difficult when using standard cell culture equipment. Recently, microfluidic techniques have arisen as powerful tools to mimic such physiological conditions. In this context, microfluidic three-dimensional cell culture systems require precise control of cell/hydrogel location because samples need to be placed within a microchamber without obstruction of surrounding elements. In this article, SU-8 is studied as structural material for the fabrication of complex cell culture devices due to its good mechanical properties, low gas permeability and sensor integration capacity. In particular, this manuscript presents a SU-8 based microdevice designed to create “self-induced” medium starvation, based on the combination of nutrient restriction and natural cell metabolism. Results show a natural migratory response towards nutrient source, showing how cells adapt to their own microenvironment modifications. The presented results demonstrate the SU-8 potential for microdevice fabrication applied to cell culture.

Sperm from sneaker male squids exhibit chemotactic swarming to CO₂.

PubMed

Hirohashi, Noritaka; Alvarez, Luis; Shiba, Kogiku; Fujiwara, Eiji; Iwata, Yoko; Mohri, Tatsuma; Inaba, Kazuo; Chiba, Kazuyoshi; Ochi, Hiroe; Supuran, Claudiu T; Kotzur, Nico; Kakiuchi, Yasutaka; Kaupp, U Benjamin; Baba, Shoji A

2013-05-06

Behavioral traits of sperm are adapted to the reproductive strategy that each species employs. In polyandrous species, spermatozoa often form motile clusters, which might be advantageous for competing with sperm from other males. Despite this presumed advantage for reproductive success, little is known about how sperm form such functional assemblies. Previously, we reported that males of the coastal squid Loligo bleekeri produce two morphologically different euspermatozoa that are linked to distinctly different mating behaviors. Consort and sneaker males use two distinct insemination sites, one inside and one outside the female's body, respectively. Here, we show that sperm release a self-attracting molecule that causes only sneaker sperm to swarm. We identified CO2 as the sperm chemoattractant and membrane-bound flagellar carbonic anhydrase as its sensor. Downstream signaling results from the generation of extracellular H(+), intracellular acidosis, and recovery from acidosis. These signaling events elicit Ca(2+)-dependent turning behavior, resulting in chemotactic swarming. These results illuminate the bifurcating evolution of sperm underlying the distinct fertilization strategies of this species. Copyright © 2013 Elsevier Ltd. All rights reserved.

Rac regulates vascular endothelial growth factor stimulated motility.

PubMed

Soga, N; Connolly, J O; Chellaiah, M; Kawamura, J; Hruska, K A

2001-01-01

During angiogenesis endothelial cells migrate towards a chemotactic stimulus. Understanding the mechanism of endothelial cell migration is critical to the therapeutic manipulation of angiogenesis and ultimately cancer prevention. Vascular endothelial growth factor (VEGF) is a potent chemotactic stimulus of endothelial cells during angiogenesis. The endothelial cell signal transduction pathway of VEGF represents a potential target for cancer therapy, but the mechanisms of post-receptor signal transduction including the roles of rho family GTPases in regulating the cytoskeletal effects of VEGF in endothelial cells are not understood. Here we analyze the mechanisms of cell migration in the mouse brain endothelial cell line (bEND3). Stable transfectants containing a tetracycline repressible expression vector were used to induce expression of Rac mutants. Endothelial cell haptotaxis was stimulated by constitutively active V12Rac on collagen and vitronectin coated supports, and chemotaxis was further stimulated by VEGF. Osteopontin coated supports were the most stimulatory to bEND3 haptotaxis, but VEGF was not effective in further increasing migration on osteopontin coated supports. Haptotaxis on support coated with collagen, vitronectin, and to a lesser degree osteopontin was inhibited by N17 Rac. N17 Rac expression blocked stimulation of endothelial cell chemotaxis by VEGF. As part of the chemotactic stimulation, VEGF caused a loss of actin organization at areas of cell-cell contact and increased stress fiber expression in endothelial cells which were directed towards pores in the transwell membrane. N17 Rac prevented the stimulation of cell-cell contact disruption and the stress fiber stimulation by VEGF. These data demonstrate two pathways of regulating endothelial cell motility, one in which Rac is activated by matrix/integrin stimulation and is a crucial modulator of endothelial cell haptotaxis. The other pathway, in the presence of osteopontin, is Rac independent. VEGF stimulated chemotaxis, is critically dependent on Rac activation. Osteopontin was a potent matrix activator of motility, and perhaps one explanation for the absence of a VEGF plus osteopontin effect is that osteopontin stimulated motility was inhibitory to the Rac pathway.

In vitro modulation of microglia motility by glioma cells is mediated by hepatocyte growth factor/scatter factor.

PubMed

Badie, B; Schartner, J; Klaver, J; Vorpahl, J

1999-05-01

Considered as immune effector cells of the central nervous system, microglia represent a major component of the inflammatory cells found in malignant gliomas. Although their role in brain tumor biology is unclear, accumulation of microglia in malignant brain tumors may be mediated through active secretion of cytokines by glioma cells. Because hepatocyte growth factor/scatter factor (HGF/SF) has been shown to modulate glioma motility through an autocrine mechanism, and because microglia have been reported to express the HGF/SF receptor Met, we hypothesized that microglia recruitment by gliomas may also occur through the secretion of HGF/SF. The effect of glioma cells in augmenting BV-2 murine microglia motility was studied by using an in vitro Boyden chamber migration assay. To determine the chemokines involved in microglia migration, neutralizing monoclonal antibodies against monocyte chemotactic protein-1 and HGF/SF were tested. Immunoblotting was used to check for the expression of HGF/SF by glioma cells, and the expression of Met by BV-2 cells was examined by flow cytometry. BV-2 migration was noted within 7 hours of incubation with both human (U251 MG and U373 MG) and murine (GL261) glioma cell lines. This migration corresponded to HGF/SF secretion by glioma cells and was completely inhibited by neutralizing monoclonal antibody against HGF/SF, but not monocyte chemotactic protein-1. Exposure of BV-2 cells to recombinant HGF/SF, but not monocyte chemotactic protein-1, resulted in their migration and down-regulation of Met in a dose-dependent fashion. HGF/SF, which plays a role in glioma motility and mitogenesis, may also act as a chemokine for microglia and may be responsible for the microglia infiltration in malignant gliomas. This active recruitment of microglia may play an important role in glioma biology.

Control of Human Endometrial Stromal Cell Motility by PDGF-BB, HB-EGF and Trophoblast-Secreted Factors

PubMed Central

Schwenke, Maren; Knöfler, Martin; Velicky, Philipp; Weimar, Charlotte H. E.; Kruse, Michelle; Samalecos, Annemarie; Wolf, Anja; Macklon, Nick S.; Bamberger, Ana-Maria; Gellersen, Birgit

2013-01-01

Human implantation involves extensive tissue remodeling at the fetal-maternal interface. It is becoming increasingly evident that not only trophoblast, but also decidualizing endometrial stromal cells are inherently motile and invasive, and likely contribute to the highly dynamic processes at the implantation site. The present study was undertaken to further characterize the mechanisms involved in the regulation of endometrial stromal cell motility and to identify trophoblast-derived factors that modulate migration. Among local growth factors known to be present at the time of implantation, heparin-binding epidermal growth factor-like growth factor (HB-EGF) triggered chemotaxis (directed locomotion), whereas platelet-derived growth factor (PDGF)-BB elicited both chemotaxis and chemokinesis (non-directed locomotion) of endometrial stromal cells. Supernatants of the trophoblast cell line AC-1M88 and of first trimester villous explant cultures stimulated chemotaxis but not chemokinesis. Proteome profiling for cytokines and angiogenesis factors revealed neither PDGF-BB nor HB-EGF in conditioned media from trophoblast cells or villous explants, while placental growth factor, vascular endothelial growth factor and PDGF-AA were identified as prominent secretory products. Among these, only PDGF-AA triggered endometrial stromal cell chemotaxis. Neutralization of PDGF-AA in trophoblast conditioned media, however, did not diminish chemoattractant activity, suggesting the presence of additional trophoblast-derived chemotactic factors. Pathway inhibitor studies revealed ERK1/2, PI3 kinase/Akt and p38 signaling as relevant for chemotactic motility, whereas chemokinesis depended primarily on PI3 kinase/Akt activation. Both chemotaxis and chemokinesis were stimulated upon inhibition of Rho-associated, coiled-coil containing protein kinase. The chemotactic response to trophoblast secretions was not blunted by inhibition of isolated signaling cascades, indicating activation of overlapping pathways in trophoblast-endometrial communication. In conclusion, trophoblast signals attract endometrial stromal cells, while PDGF-BB and HB-EGF, although not identified as trophoblast-derived, are local growth factors that may serve to fine-tune directed and non-directed migration at the implantation site. PMID:23349855

Growth-related gene product {alpha}: A chemotactic cytokine for neutrophils in rheumatoid arthritis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koch, A.E.; Pope, R.M.; Shah, M.R.

Leukocyte recruitment is critical in the inflammation seen in rheumatoid arthritis (RA). To determine whether the chemokine growth-related gene product {alpha} (gro{alpha}) plays a role in this process, we examined synovial tissue (ST), synovial fluid (SF), and plasma samples from 102 patients with arthritis. RA SF contained more antigenic gro{alpha} (mean 5.3 {+-} 1.9 ng/ml) than did SFs from either osteoarthritis (OA) or other forms of arthritis (mean 0.1 ng/ml) (p < 0.05). RA plasma contained more gro{alpha} (mean 4.3 {+-} 1.8 ng/ml) than normal plasma (mean 0.1 ng/ml) (p < 0.05). RA ST fibroblasts (1.2 x 10{sup 5}/cells/ml RPMImore » 1640/24 h) produced antigenic gro{alpha} (mean 0.2 {+-} 0.1 ng/ml), and this production was increased significantly upon incubation with TNF-{alpha} (mean 1.3 {+-} 0.3 ng/ml) or IL-1{beta} (mean 2.3 {+-} 0.6 ng/ml) (p < 0.05). Cells from RA SF also produced gro{alpha}: neutrophils (PMNs) (10{sup 7} cells/ml/24 h) produced 3.7 {+-} 0.7 ng/ml. RA SF mononuclear cells produced gro{alpha}, particularly upon incubation with LPS or PHA. Immunoreactive ST gro{alpha} was found in greater numbers of RA compared with either OA or normal lining cells, as well as in RA compared with OA subsynovial macrophages (p < 0.05). IL-8 accounted for a mean of 36% of the RA SF chemotactic activity for PMNs, while epithelial neutrophil-activating peptide-78 accounted for 34%, and gro{alpha} for 28%, of this activity. Combined neutralization of all three chemokines in RA SFs resulted in a mean decrease of 50% of the chemotactic activity for PMNs present in the RA SFs. These results indicate that gro{alpha} plays an important role in the ingress of PMNs into the RA joint. 54 refs., 6 figs., 1 tab.« less

Macrophage mitochondrial oxidative stress promotes atherosclerosis and nuclear factor-κB-mediated inflammation in macrophages.

PubMed

Wang, Ying; Wang, Gary Z; Rabinovitch, Peter S; Tabas, Ira

2014-01-31

Mitochondrial oxidative stress (mitoOS) has been shown to correlate with the progression of human atherosclerosis. However, definitive cell type-specific causation studies in vivo are lacking, and the molecular mechanisms of potential proatherogenic effects remain to be determined. Our aims were to assess the importance of macrophage mitoOS in atherogenesis and to explore the underlying molecular mechanisms. We first validated Western diet-fed Ldlr(-/-) mice as a model of human mitoOS-atherosclerosis association by showing that non-nuclear oxidative DNA damage, a marker of mitoOS in lesional macrophages, correlates with aortic root lesion development. To investigate the importance of macrophage mitoOS, we used a genetic engineering strategy in which the OS suppressor catalase was ectopically expressed in mitochondria (mCAT) in macrophages. MitoOS in lesional macrophages was successfully suppressed in these mice, and this led to a significant reduction in aortic root lesional area. The mCAT lesions had less monocyte-derived cells, less Ly6c(hi) monocyte infiltration into lesions, and lower levels of monocyte chemotactic protein-1. The decrease in lesional monocyte chemotactic protein-1 was associated with the suppression of other markers of inflammation and with decreased phosphorylation of RelA (NF-κB p65), indicating decreased activation of the proinflammatory NF-κB pathway. Using models of mitoOS in cultured macrophages, we showed that mCAT suppressed monocyte chemotactic protein-1 expression by decreasing the activation of the IκB-kinase β-RelA NF-κB pathway. MitoOS in lesional macrophages amplifies atherosclerotic lesion development by promoting NF-κB-mediated entry of monocytes and other inflammatory processes. In view of the mitoOS-atherosclerosis link in human atheromata, these findings reveal a potentially new therapeutic target to prevent the progression of atherosclerosis.

Role of elevated plasma soluble ICAM-1 and bronchial lavage fluid IL-8 levels as markers of chronic lung disease in premature infants.

PubMed Central

Little, S.; Dean, T.; Bevin, S.; Hall, M.; Ashton, M.; Church, M.; Warner, J.; Shute, J.

1995-01-01

BACKGROUND--Pulmonary neutrophilia characterises both the relatively transient inflammation associated with infant respiratory distress syndrome (IRDS) and the persistent inflammation of chronic lung disease. The possibility that persistently raised markers of inflammation indicate the development of chronic lung disease in low birth weight (< 1730 g) preterm (< 31 weeks) infants was therefore investigated. METHODS--Soluble ICAM-1 (sICAM-1) levels in plasma, and interleukin (IL)-8 and myeloperoxidase (MPO) levels in bronchial lavage fluid (BLF) obtained from 17 infants on days 1, 5, and 14 following birth were measured and correlations with the number of neutrophils in BLF sought. Peripheral neutrophils were isolated on Polymorphoprep and chemotactic responsiveness to IL-8 was assessed using micro Boyden chambers. RESULTS--Sixteen infants developed IRDS and, of these, 10 infants subsequently developed chronic lung disease. Levels of IL-8 in BLF at 14 days of age correlated with the long term requirement for intermittent positive pressure ventilation (IPPV). Interleukin 8 levels in BLF correlated with neutrophil numbers and MPO concentration, suggesting both recruitment and activation in response to this cytokine. Antibody depletion studies showed that approximately 50% of total neutrophil chemotactic activity in BLF was due to IL-8. No difference in peripheral neutrophil chemotactic responsiveness at any age was observed for infants with IRDS or chronic lung disease. Plasma soluble intercellular adhesion molecule (sICAM-1) was higher at 14 days of age in infants who developed chronic lung disease than in those with resolving IRDS, and correlated with severity of disease, as indicated by duration of IPPV. CONCLUSIONS--The results indicate that high levels of plasma sICAM-1 and IL-8 in BLF at day 14 correlate with the development of chronic lung disease and indicate the severity of disease. PMID:7491556

Agonist-dependent phosphorylation of N-formylpeptide and activation peptide from the fifth component of C (C5a) chemoattractant receptors in differentiated HL60 cells.

PubMed

Tardif, M; Mery, L; Brouchon, L; Boulay, F

1993-04-15

Attenuation of signaling is a key step in controlling the cytotoxic potential of leukocyte responses to chemotactic factors. Antipeptide antibodies, directed against the N-formyl chemotactic peptide receptor (FPR) and the activation peptide from the fifth component of C (C5a) anaphylatoxin receptor (C5aR) of human neutrophils, were used to analyze the ability of these receptors to be phosphorylated. Our data show that, in granulocyte-like differentiated HL-60 cells, both FPR and C5aR undergo an agonist dose-dependent phosphorylation that reaches completion in less than 2 to 3 min, consistent with the rate and the dose-dependent attenuation of signaling in phagocytes. Therefore, phosphorylation might be one of the possible mechanisms involved in the desensitization process of FPR and C5aR. Addition of either C5a or the protein kinase C activator (PMA) did not appear to induce the phosphorylation of FPR in the absence of FMLP or to modulate the phosphorylation of the latter at low concentrations of agonist. In contrast, although FMLP at a saturating concentration barely stimulated the phosphorylation of unoccupied C5aR, it markedly potentiated C5aR phosphorylation in cells exposed to low concentrations of C5a. Moreover, PMA was able to induce C5aR phosphorylation in the absence of agonist, indicating that protein kinase C or protein kinase C-activated kinase(s) could be involved in the phosphorylation of C5aR. Pretreatment of cells with staurosporine, a potent but nonspecific inhibitor of protein kinase C, resulted in the partial inhibition of both FPR and C5aR phosphorylation induced by saturating concentrations of agonist, suggesting that a kinase different from protein kinase C might be mainly responsible for the phosphorylation of these chemotactic receptors.

Cell recruiting chemokine-loaded sprayable gelatin hydrogel dressings for diabetic wound healing.

PubMed

Yoon, Dong Suk; Lee, Yunki; Ryu, Hyun Aae; Jang, Yeonsue; Lee, Kyoung-Mi; Choi, Yoorim; Choi, Woo Jin; Lee, Moses; Park, Kyung Min; Park, Ki Dong; Lee, Jin Woo

2016-07-01

In this study, we developed horseradish peroxidase (HRP)-catalyzed sprayable gelatin hydrogels (GH) as a bioactive wound dressing that can deliver cell-attracting chemotactic cytokines to the injured tissues for diabetic wound healing. We hypothesized that topical administration of chemokines using GH hydrogels might improve wound healing by inducing recruitment of the endogenous cells. Two types of chemokines (interleukin-8; IL-8, macrophage inflammatory protein-3α; MIP-3α) were simply loaded into GH hydrogels during in situ cross-linking, and then their wound-healing effects were evaluated in streptozotocin-induced diabetic mice. The incorporation of chemokines did not affect hydrogels properties including swelling ratio and mechanical stiffness, and the bioactivities of IL-8 and MIP-3α released from hydrogel matrices were stably maintained. In vivo transplantation of chemokine-loaded GH hydrogels facilitated cell infiltration into the wound area, and promoted wound healing with enhanced re-epithelialization/neovascularization and increased collagen deposition, compared with no treatment or the GH hydrogel alone. Based on our results, we suggest that cell-recruiting chemokine-loaded GH hydrogel dressing can serve as a delivery platform of various therapeutic proteins for wound healing applications. Despite development of materials combined with therapeutic agents for diabetic wound treatment, impaired wound healing by insufficient chemotactic responses still remain as a significant problem. In this study, we have developed enzyme-catalyzed gelatin (GH) hydrogels as a sprayable dressing material that can deliver cell-attracting chemokines for diabetic wound healing. The chemotactic cytokines (IL-8 and MIP-3α) were simply loaded within hydrogel during in situ gelling, and wound healing efficacy of chemokine-loaded GH hydrogels was investigated in STZ-induced diabetic mouse model. These hydrogels significantly promoted wound-healing efficacy with faster wound closure, neovascularization, and thicker granulation. Therefore, we expect that HRP-catalyzed in situ forming GH hydrogels can serve as an injectable/sprayable carrier of various therapeutic agents for wound healing applications. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Multiscale mechanisms of cell migration during development: theory and experiment.

PubMed

McLennan, Rebecca; Dyson, Louise; Prather, Katherine W; Morrison, Jason A; Baker, Ruth E; Maini, Philip K; Kulesa, Paul M

2012-08-01

Long-distance cell migration is an important feature of embryonic development, adult morphogenesis and cancer, yet the mechanisms that drive subpopulations of cells to distinct targets are poorly understood. Here, we use the embryonic neural crest (NC) in tandem with theoretical studies to evaluate model mechanisms of long-distance cell migration. We find that a simple chemotaxis model is insufficient to explain our experimental data. Instead, model simulations predict that NC cell migration requires leading cells to respond to long-range guidance signals and trailing cells to short-range cues in order to maintain a directed, multicellular stream. Experiments confirm differences in leading versus trailing NC cell subpopulations, manifested in unique cell orientation and gene expression patterns that respond to non-linear tissue growth of the migratory domain. Ablation experiments that delete the trailing NC cell subpopulation reveal that leading NC cells distribute all along the migratory pathway and develop a leading/trailing cellular orientation and gene expression profile that is predicted by model simulations. Transplantation experiments and model predictions that move trailing NC cells to the migratory front, or vice versa, reveal that cells adopt a gene expression profile and cell behaviors corresponding to the new position within the migratory stream. These results offer a mechanistic model in which leading cells create and respond to a cell-induced chemotactic gradient and transmit guidance information to trailing cells that use short-range signals to move in a directional manner.

Differential Contributions of Olfactory Receptor Neurons in a Drosophila Olfactory Circuit

PubMed Central

Newquist, Gunnar; Novenschi, Alexandra; Kohler, Donovan

2016-01-01

Abstract The ability of an animal to detect, discriminate, and respond to odors depends on the functions of its olfactory receptor neurons (ORNs). The extent to which each ORN, upon activation, contributes to chemotaxis is not well understood. We hypothesized that strong activation of each ORN elicits a different behavioral response in the Drosophila melanogaster larva by differentially affecting the composition of its navigational behavior. To test this hypothesis, we exposed Drosophila larvae to specific odorants to analyze the effect of individual ORN activity on chemotaxis. We used two different behavioral paradigms to analyze the chemotaxis response of larvae to odorants. When tested with five different odorants that elicit strong physiological responses from single ORNs, larval behavioral responses toward each odorant differed in the strength of attraction as well as in the composition of discrete navigational elements, such as runs and turns. Further, behavioral responses to odorants did not correlate with either the strength of odor gradients tested or the sensitivity of each ORN to its cognate odorant. Finally, we provide evidence that wild-type larvae with all ORNs intact exhibit higher behavioral variance than mutant larvae that have only a single pair of functional ORNs. We conclude that individual ORNs contribute differently to the olfactory circuit that instructs chemotactic responses. Our results, along with recent studies from other groups, suggest that ORNs are functionally nonequivalent units. These results have implications for understanding peripheral odor coding. PMID:27570823

Quantifying oxygen in paper-based cell cultures with luminescent thin film sensors.

PubMed

Boyce, Matthew W; Kenney, Rachael M; Truong, Andrew S; Lockett, Matthew R

2016-04-01

Paper-based scaffolds are an attractive material for generating 3D tissue-like cultures because paper is readily available and does not require specialized equipment to pattern, cut, or use. By controlling the exchange of fresh culture medium with the paper-based scaffolds, we can engineer diffusion-dominated environments similar to those found in spheroids or solid tumors. Oxygen tension directly regulates cellular phenotype and invasiveness through hypoxia-inducible transcription factors and also has chemotactic properties. To date, gradients of oxygen generated in the paper-based cultures have relied on cellular response-based readouts. In this work, we prepared a luminescent thin film capable of quantifying oxygen tensions in apposed cell-containing paper-based scaffolds. The oxygen sensors, which are polystyrene films containing a Pd(II) tetrakis(pentafluorophenyl)porphyrin dye, are photostable, stable in culture conditions, and not cytotoxic. They have a linear response for oxygen tensions ranging from 0 to 160 mmHg O2, and a Stern-Volmer constant (K sv) of 0.239 ± 0.003 mmHg O2 (-1). We used these oxygen-sensing films to measure the spatial and temporal changes in oxygen tension for paper-based cultures containing a breast cancer line that was engineered to constitutively express a fluorescent protein. By acquiring images of the oxygen-sensing film and the fluorescently labeled cells, we were able to approximate the oxygen consumption rates of the cells in our cultures.

Potential mechanism of corpus-predominant gastritis after PPI therapy in Helicobacter pylori-positive patients with GERD.

PubMed

Mukaisho, Ken-ichi; Hagiwara, Tadashi; Nakayama, Takahisa; Hattori, Takanori; Sugihara, Hiroyuki

2014-09-14

The long-term use of proton pump inhibitors (PPIs) exacerbates corpus atrophic gastritis in patients with Helicobacter pylori (H. pylori) infection. To identify a potential mechanism for this change, we discuss interactions between pH, bile acids, and H. pylori. Duodenogastric reflux, which includes bile, occurs in healthy individuals, and bile reflux is increased in patients with gastroesophageal reflux disease (GERD). Diluted human plasma and bile acids have been found to be significant chemoattractants and chemorepellents, respectively, for the bacillus H. pylori. Although only taurine conjugates, with a pKa of 1.8-1.9, are soluble in an acidic environment, glycine conjugates, with a pKa of 4.3-5.2, as well as taurine-conjugated bile acids are soluble in the presence of PPI therapy. Thus, the soluble bile acid concentrations in the gastric contents of patients with GERD after continuous PPI therapy are considerably higher than that in those with intact acid production. In the distal stomach, the high concentration of soluble bile acids is likely to act as a bactericide or chemorepellent for H. pylori. In contrast, the mucous layer in the proximal stomach has an optimal bile concentration that forms chemotactic gradients with plasma components required to direct H. pylori to the epithelial surface. H. pylori may then colonize in the stomach body rather than in the pyloric antrum, which may explain the occurrence of corpus-predominant gastritis after PPI therapy in H. pylori-positive patients with GERD.

Image-Based Measurement of H2O2 Reaction-Diffusion in Wounded Zebrafish Larvae.

PubMed

Jelcic, Mark; Enyedi, Balázs; Xavier, João B; Niethammer, Philipp

2017-05-09

Epithelial injury induces rapid recruitment of antimicrobial leukocytes to the wound site. In zebrafish larvae, activation of the epithelial NADPH oxidase Duox at the wound margin is required early during this response. Before injury, leukocytes are near the vascular region, that is, ∼100-300 μm away from the injury site. How Duox establishes long-range signaling to leukocytes is unclear. We conceived that extracellular hydrogen peroxide (H 2 O 2 ) generated by Duox diffuses through the tissue to directly regulate chemotactic signaling in these cells. But before it can oxidize cellular proteins, H 2 O 2 must get past the antioxidant barriers that protect the cellular proteome. To test whether, or on which length scales this occurs during physiological wound signaling, we developed a computational method based on reaction-diffusion principles that infers H 2 O 2 degradation rates from intravital H 2 O 2 -biosensor imaging data. Our results indicate that at high tissue H 2 O 2 levels the peroxiredoxin-thioredoxin antioxidant chain becomes overwhelmed, and H 2 O 2 degradation stalls or ceases. Although the wound H 2 O 2 gradient reaches deep into the tissue, it likely overcomes antioxidant barriers only within ∼30 μm of the wound margin. Thus, Duox-mediated long-range signaling may require other spatial relay mechanisms besides extracellular H 2 O 2 diffusion. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Extracellular calcium elicits a chemokinetic response from monocytes in vitro and in vivo

NASA Technical Reports Server (NTRS)

Olszak, I. T.; Poznansky, M. C.; Evans, R. H.; Olson, D.; Kos, C.; Pollak, M. R.; Brown, E. M.; Scadden, D. T.; O'Malley, B. W. (Principal Investigator)

2000-01-01

Recruitment of macrophages to sites of cell death is critical for induction of an immunologic response. Calcium concentrations in extracellular fluids vary markedly, and are particularly high at sites of injury or infection. We hypothesized that extracellular calcium participates in modulating the immune response, perhaps acting via the seven-transmembrane calcium-sensing receptor (CaR) on mature monocytes/macrophages. We observed a dose-dependent increase in monocyte chemotaxis in response to extracellular calcium or the selective allosteric CaR activator NPS R-467. In contrast, monocytes derived from mice deficient in CaR lacked the normal chemotactic response to a calcium gradient. Notably, CaR activation of monocytes bearing the receptor synergistically augmented the transmigration response of monocytes to the chemokine MCP-1 in association with increased cell-surface expression of its cognate receptor, CCR2. Conversely, stimulation of monocytes with MCP-1 or SDF-1alpha reciprocally increased CaR expression, suggesting a dual-enhancing interaction of Ca(2+) with chemokines in recruiting inflammatory cells. Subcutaneous administration in mice of Ca(2+), MCP-1, or (more potently) the combination of Ca(2+) and MCP-1, elicited an inflammatory infiltrate consisting of monocytes/macrophages. Thus extracellular calcium functions as an ionic chemokinetic agent capable of modulating the innate immune response in vivo and in vitro by direct and indirect actions on monocytic cells. Calcium deposition may be both consequence and cause of chronic inflammatory changes at sites of injury, infection, and atherosclerosis.

On a Parabolic-Elliptic system with chemotaxis and logistic type growth

NASA Astrophysics Data System (ADS)

Galakhov, Evgeny; Salieva, Olga; Tello, J. Ignacio

2016-10-01

We consider a nonlinear PDEs system of two equations of Parabolic-Elliptic type with chemotactic terms. The system models the movement of a biological population ;u; towards a higher concentration of a chemical agent ;w; in a bounded and regular domain Ω ⊂RN for arbitrary N ∈ N. After normalization, the system is as follows

High-fat diet enhances and monocyte chemoattractant protein-1 deficiency reduces bone loss in mice with pulmonary metastases of Lewis lung carcinoma

USDA-ARS?s Scientific Manuscript database

Bone is adversely affected by metastasis and metastasis-associated complications. Obesity is a risk factor for both bone and cancer. Adipose tissue is an endocrine organ that produces pro-inflammatory adipokines, such as monocyte chemotactic protein-1 (MCP-1), that contribute to obesity and obesit...

Clarifying CB2 receptor-dependent and independent effects of THC on human lung epithelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarafian, Theodore; Montes, Cindy; Harui, Airi

Marijuana smoking is associated with a number of abnormal findings in the lungs of habitual smokers. Previous studies revealed that {delta}{sup 9}-tetrahydrocannabinol (THC) caused mitochondrial injury in primary lung epithelial cells and in the cell line, A549 [Sarafian, T. A., Kouyoumjian, S., Khoshaghideh, F., Tashkin, D. P., and Roth, M. D. (2003). Delta 9-tetrahydrocannabinol disrupts mitochondrial function and cell energetics. Am J Physiol Lung Cell Mol Physiol 284, L298-306; Sarafian, T., Habib, N., Mao, J. T., Tsu, I. H., Yamamoto, M. L., Hsu, E., Tashkin, D. P., and Roth, M. D. (2005). Gene expression changes in human small airway epithelialmore » cells exposed to Delta9-tetrahydrocannabinol. Toxicol Lett 158, 95-107]. The role of cannabinoid receptors in this injury was unclear, as was the potential impact on cell function. In order to investigate these questions, A549 cells were engineered to over-express the type 2 cannabinoid receptor (CB2R) using a self-inactivating lentiviral vector. This transduction resulted in a 60-fold increase in CB2R mRNA relative to cells transduced with a control vector. Transduced cell lines were used to study the effects of THC on chemotactic activity and mitochondrial function. Chemotaxis in response to a 10% serum gradient was suppressed in a concentration-dependent manner by exposure to THC. CB2R-transduced cells exhibited less intrinsic chemotactic activity (p < 0.05) and were 80- to 100-fold more sensitive to the inhibitory effects of THC. Studies using SR144528, a selective CB2R antagonist, verified that these effects were mediated by the CB2R. Marijuana smoke extract, but not smoke extracts from tobacco or placebo marijuana cigarettes, reproduced these effects (p < 0.05). THC decreased ATP level and mitochondrial membrane potential ({psi}{sub m}) in both control and CB2R-transduced cells. However, these decreases did not play a significant role in chemotaxis inhibition since cyclosporine A, which protected against ATP loss, did not increase cell migration. Moreover, CB2R-transduced cells displayed higher {psi}{sub m} than did control cells. Since both {psi}{sub m} and chemotaxis are regulated by intracellular signaling, we investigated the effects of THC on the activation of multiple signaling pathways. Serum exposure activated several signaling events of which phosphorylation of I{kappa}B-{alpha} and JNK was regulated in a CB2R- and THC-dependent manner. We conclude that airway epithelial cells are sensitive to both CB2R-dependent and independent effects mediated by THC.« less

Stabilization in a two-species chemotaxis system with a logistic source

NASA Astrophysics Data System (ADS)

Tello, J. I.; Winkler, M.

2012-05-01

We study a system of three partial differential equations modelling the spatio-temporal behaviour of two competitive populations of biological species both of which are attracted chemotactically by the same signal substance. More precisely, we consider the initial-boundary value problem for \\[ \\begin{equation*} \\fl\\left\\{ \\begin{array}{@{}l} u_t= d_1\\Delta u - \\chi_1 \

N-3 and n-6 polyunsaturated fatty acids differentially regulate adipose angiotensinogen and other inflammatory adipokines in part via NF-kB dependent mechanisms

USDA-ARS?s Scientific Manuscript database

Excessive secretion of angiotensinogen (Agt) and other adipokines such as Interleukin-6 (IL-6) and Monocyte chemotactic protein-1 (MCP-1) have been linked to obesity and associated metabolic disorders, with a common feature being inflammation. We have previously shown that n-3 polyunsaturated fatty ...

Characterizing Myeloid Cell Activation in NF1 Vasculopathy

DTIC Science & Technology

2017-07-01

stimulation of its receptor (CCR2) and the generation of reactive oxygen species, which are generated in excessive quantities by neurofibromin-deficient...macrophages via monocyte chemotactic peptide-1 (MCP-1) stimulation of its receptor (CCR2) and the generation of reactive oxygen species, which are...neurofibromatosis; stenosis; aneurysm; MCP-1; CCR2; reactive oxygen species; superoxide; macrophages; monocytes; arteries; cardiovascular disease Major

Uptake of apoptotic leukocytes by synovial lining macrophages inhibits immune complex-mediated arthritis.

PubMed

van Lent, P L; Licht, R; Dijkman, H; Holthuysen, A E; Berden, J H; van den Berg, W B

2001-11-01

Previously we have shown that synovial lining macrophages (SLMs) determine the onset of experimental immune complex-mediated arthritis (ICA). During joint inflammation, many leukocytes undergo apoptosis, and removal of leukocytes by SLMs may regulate resolution of inflammation. In this study we investigated binding and uptake of apoptotic leukocytes by SLMs and its impact on the onset of murine experimental arthritis. We used an in vitro model to evaluate phagocytosis of apoptotic cells on chemotaxis. Phagocytosis of apoptotic thymocytes resulted in a significant decrease (58%) of chemotactic activity for polymorphonuclear neutrophils (PMNs). If apoptotic cells were injected directly into a normal murine knee joint, SLMs resulted in a prominent uptake of cells. After ICA induction, electron micrographs showed that apoptotic leukocytes were evidently present in SLMs on days 1 and 2. Injection of apoptotic leukocytes into the knee joint 1 h before induction of ICA significantly inhibited PMN infiltration into the knee joint at 24 h (61% decrease). This study indicates that uptake of apoptotic leukocytes by SLM reduces chemotactic activity and inhibits the onset of experimental arthritis. These findings indicate an important mechanism in the resolution of joint inflammation.

Chemotaxis and degradation of organophosphate compound by a novel moderately thermo-halo tolerant Pseudomonas sp. strain BUR11: evidence for possible existence of two pathways for degradation.

PubMed

Pailan, Santanu; Saha, Pradipta

2015-01-01

An organophosphate (OP) degrading chemotactic bacterial strain BUR11 isolated from an agricultural field was identified as a member of Pseudomonas genus on the basis of its 16S rRNA gene sequence. The strain could utilize parathion, chlorpyrifos and their major hydrolytic intermediates as sole source of carbon for its growth and exhibited positive chemotactic response towards most of them. Optimum concentration of parathion for its growth was recorded to be 200 ppm and 62% of which was degraded within 96 h at 37 °C. Growth studies indicated the strain to be moderately thermo-halo tolerant in nature. Investigation based on identification of intermediates of parathion degradation by thin layer chromatography (TLC), high performance liquid chromatography (HPLC), gas chromatography (GC) and liquid chromatography mass spectrometry (LC-MS/MS) provided evidence for possible existence of two pathways. The first pathway proceeds via 4-nitrophenol (4-NP) while the second proceeds through formation of 4-aminoparathion (4-APar), 4-aminophenol (4-AP) and parabenzoquinone (PBQ). This is the first report of chemotaxis towards organophosphate compound by a thermo-halo tolerant bacterium.

Chemotaxis and degradation of organophosphate compound by a novel moderately thermo-halo tolerant Pseudomonas sp. strain BUR11: evidence for possible existence of two pathways for degradation

PubMed Central

Pailan, Santanu

2015-01-01

An organophosphate (OP) degrading chemotactic bacterial strain BUR11 isolated from an agricultural field was identified as a member of Pseudomonas genus on the basis of its 16S rRNA gene sequence. The strain could utilize parathion, chlorpyrifos and their major hydrolytic intermediates as sole source of carbon for its growth and exhibited positive chemotactic response towards most of them. Optimum concentration of parathion for its growth was recorded to be 200 ppm and 62% of which was degraded within 96 h at 37 °C. Growth studies indicated the strain to be moderately thermo-halo tolerant in nature. Investigation based on identification of intermediates of parathion degradation by thin layer chromatography (TLC), high performance liquid chromatography (HPLC), gas chromatography (GC) and liquid chromatography mass spectrometry (LC-MS/MS) provided evidence for possible existence of two pathways. The first pathway proceeds via 4-nitrophenol (4-NP) while the second proceeds through formation of 4-aminoparathion (4-APar), 4-aminophenol (4-AP) and parabenzoquinone (PBQ). This is the first report of chemotaxis towards organophosphate compound by a thermo-halo tolerant bacterium. PMID:26587344

A bacterial pathogen uses dimethylsulfoniopropionate as a cue to target heat-stressed corals.

PubMed

Garren, Melissa; Son, Kwangmin; Raina, Jean-Baptiste; Rusconi, Roberto; Menolascina, Filippo; Shapiro, Orr H; Tout, Jessica; Bourne, David G; Seymour, Justin R; Stocker, Roman

2014-05-01

Diseases are an emerging threat to ocean ecosystems. Coral reefs, in particular, are experiencing a worldwide decline because of disease and bleaching, which have been exacerbated by rising seawater temperatures. Yet, the ecological mechanisms behind most coral diseases remain unidentified. Here, we demonstrate that a coral pathogen, Vibrio coralliilyticus, uses chemotaxis and chemokinesis to target the mucus of its coral host, Pocillopora damicornis. A primary driver of this response is the host metabolite dimethylsulfoniopropionate (DMSP), a key element in the global sulfur cycle and a potent foraging cue throughout the marine food web. Coral mucus is rich in DMSP, and we found that DMSP alone elicits chemotactic responses of comparable intensity to whole mucus. Furthermore, in heat-stressed coral fragments, DMSP concentrations increased fivefold and the pathogen's chemotactic response was correspondingly enhanced. Intriguingly, despite being a rich source of carbon and sulfur, DMSP is not metabolized by the pathogen, suggesting that it is used purely as an infochemical for host location. These results reveal a new role for DMSP in coral disease, demonstrate the importance of chemical signaling and swimming behavior in the recruitment of pathogens to corals and highlight the impact of increased seawater temperatures on disease pathways.

Vascular Endothelial Growth Factor (VEGF) Promotes Assembly of the p130Cas Interactome to Drive Endothelial Chemotactic Signaling and Angiogenesis.

PubMed

Evans, Ian M; Kennedy, Susan A; Paliashvili, Ketevan; Santra, Tapesh; Yamaji, Maiko; Lovering, Ruth C; Britton, Gary; Frankel, Paul; Kolch, Walter; Zachary, Ian C

2017-02-01

p130Cas is a polyvalent adapter protein essential for cardiovascular development, and with a key role in cell movement. In order to identify the pathways by which p130Cas exerts its biological functions in endothelial cells we mapped the p130Cas interactome and its dynamic changes in response to VEGF using high-resolution mass spectrometry and reconstruction of protein interaction (PPI) networks with the aid of multiple PPI databases. VEGF enriched the p130Cas interactome in proteins involved in actin cytoskeletal dynamics and cell movement, including actin-binding proteins, small GTPases and regulators or binders of GTPases. Detailed studies showed that p130Cas association of the GTPase-binding scaffold protein, IQGAP1, plays a key role in VEGF chemotactic signaling, endothelial polarization, VEGF-induced cell migration, and endothelial tube formation. These findings indicate a cardinal role for assembly of the p130Cas interactome in mediating the cell migratory response to VEGF in angiogenesis, and provide a basis for further studies of p130Cas in cell movement. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Activation of normal neutrophils by anti-neutrophil cytoplasm antibodies.

PubMed Central

Keogan, M T; Esnault, V L; Green, A J; Lockwood, C M; Brown, D L

1992-01-01

Anti-neutrophil cytoplasm antibodies (ANCA) are markers of systemic vasculitis for which a pathogenetic role has been postulated. We have examined the effect of these autoantibodies on the function of normal human neutrophils in vitro. In the presence of ANCA positive sera luminol-amplified chemiluminescence was significantly increased compared to the values seen in the presence of normal or anti-double stranded DNA positive sera (P < 0.01). Five of six ANCA positive F(ab)2 preparations also produced significant neutrophil activation as demonstrated by the chemiluminescence response. This response was totally abrogated by the addition of neutrophil cytoplasm extract, containing the ANCA antigen. Addition of inhibitors to the chemiluminescence system demonstrated that the chemiluminescence response was inhibited by azide and salicylhydroxamic acid and reduced by histidine, suggesting that the chemiluminescence response was due to activation of myeloperoxidase, with generation of singlet oxygen. The chemotactic response to f-Met-Leu-Phe, a bacterial chemotactic peptide, was significantly augmented in the presence of ANCA. Chemotaxis to zymosan-activated serum and chemokinesis was not affected. Phagocytosis was also unaffected. We propose that neutrophil activation and modulation of neutrophil migration by ANCA may be of pathogenetic significance in systemic vasculitis. PMID:1424279

Microcystins Alter Chemotactic Behavior in Caenorhabditis elegans by Selectively Targeting the AWA Sensory Neuron

PubMed Central

Moore, Caroline E.; Lein, Pamela J.; Puschner, Birgit

2014-01-01

Harmful algal blooms expose humans and animals to microcystins (MCs) through contaminated drinking water. While hepatotoxicity following acute exposure to MCs is well documented, neurotoxicity after sub-lethal exposure is poorly understood. We developed a novel statistical approach using a generalized linear model and the quasibinomial family to analyze neurotoxic effects in adult Caenorhabditis elegans exposed to MC-LR or MC-LF for 24 h. Selective effects of toxin exposure on AWA versus AWC sensory neuron function were determined using a chemotaxis assay. With a non-monotonic response MCs altered AWA but not AWC function, and MC-LF was more potent than MC-LR. To probe a potential role for protein phosphatases (PPs) in MC neurotoxicity, we evaluated the chemotactic response in worms exposed to the PP1 inhibitor tautomycin or the PP2A inhibitor okadaic acid for 24 h. Okadaic acid impaired both AWA and AWC function, while tautomycin had no effect on function of either neuronal cell type at the concentrations tested. These findings suggest that MCs alter the AWA neuron at concentrations that do not cause AWC toxicity via mechanisms other than PP inhibition. PMID:24918360

The kampo medicine Daikenchuto inhibits peritoneal fibrosis in mice.

PubMed

Kitamura, Mineaki; Nishino, Tomoya; Obata, Yoko; Oka, Satoru; Abe, Shinichi; Muta, Kumiko; Ozono, Yoshiyuki; Koji, Takehiko; Kohno, Shigeru

2015-01-01

Long-term peritoneal dialysis therapy causes inflammation and histological changes in the peritoneal membrane. Inflammation generally activates fibroblasts and results in fibroblast-myofibroblast differentiation. Heat-shock protein 47 (HSP 47), a collagen-specific molecular chaperone, is localized in myofibroblasts and is involved in the progression of peritoneal fibrosis. Daikenchuto (DKT), a Kampo medicine, is used to prevent postoperative colon adhesion. It inhibits inflammation and HSP 47 expression in the gastrointestinal tract. We examined the effect of DKT on chlorhexidine gluconate (CG)-induced peritoneal fibrosis in mice injected with 0.1% CG dissolved in 15% ethanol. DKT was dissolved in the drinking water. Histological changes were assessed using Masson trichrome staining. Cells expressing α-smooth muscle actin (α-SMA), HSP 47, phospho-Smad 2/3, F4/80, and monocyte chemotactic protein-1 were examined immunohistochemically. Compared with the control group, the peritoneal tissues of the CG group were markedly thickened, and the number of cells expressing α-SMA, HSP 47, phospho-Smad 2/3, F4/80, and monocyte chemotactic protein-1 was significantly increased. However, these changes were inhibited in the DKT-treated group. These results indicate that DKT can prevent peritoneal fibrosis by inhibiting inflammation and HSP 47 expression.

The Anti-Inflammatory Cytokine Interleukin-19 Is Expressed in and Angiogenic for Human Endothelial Cells

PubMed Central

Jain, Surbhi; Gabunia, Khatuna; Kelemen, Sheri E.; Panetti, Tracee S.; Autieri, Michael V.

2010-01-01

OBJECTIVE The expression and effects of anti-inflammatory interleukins on endothelial cell (EC) activation and development of angiogenesis is uncharacterized. The purpose of this study is to characterize the expression and function of Interleukin-19 (IL-19), a recently described Th2 anti-inflammatory interleukin on EC pathophysiology. METHODS and RESULTS We demonstrate by immunohistochemistry and immunoblot that IL-19 is expressed in inflamed, but not normal human coronary endothelium, and can be induced in cultured human EC by serum and bFGF. IL-19 is mitogenic, chemotactic, and promotes cell EC spreading. IL-19 activates the signaling proteins STAT3, p44/42, and Rac1. In functional ex vivo studies, IL-19 promotes cord-like structure formation of cultured EC and also enhances microvessel sprouting in the mouse aortic ring assay. IL-19 induces tube formation in matrigel plugs in vivo. CONCLUSIONS These data are the first to report expression of the anti-inflammatory interleukin IL-19 in EC, and the first to indicate that IL-19 is mitogenic and chemotactic for EC, and can induce the angiogenic potential of EC. PMID:20966397

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) promotes glioblastoma cell chemotaxis via Lyn activation

PubMed Central

Tran, Nhan L.

2014-01-01

The long-term survival of patients with glioblastoma is compromised by the proclivity for local invasion into the surrounding normal brain, escaping surgical resection and contributing to therapeutic resistance. Tumor necrosis factor-like weak inducer of apoptosis (TWEAK), a member of the tumor necrosis factor superfamily, can stimulate glioma cell invasion via binding to fibroblast growth factor-inducible 14 (Fn14) and subsequent activation of the Rho guanosine triphosphatase family member Rac1. Here, we demonstrate that TWEAK acts as a chemotactic factor for glioma cells, a potential process for driving cell invasion into the surrounding brain tissue. TWEAK exposure induced the activation of Src family kinases (SFKs), and pharmacologic suppression of SFK activity inhibited TWEAK-induced chemotactic migration. We employed a multiplexed Luminex assay and identified Lyn as a candidate SFK activated by TWEAK. Depletion of Lyn suppressed TWEAK-induced chemotaxis and Rac1 activity. Furthermore, Lyn gene expression levels increase with primary glioma tumor grade and inversely correlate with patient survival. These results show that TWEAK-induced glioma cell chemotaxis is dependent upon Lyn kinase function and, thus, provides opportunities for therapeutic targeting of this deadly disease. PMID:23975833

Cyclic stretch augments production of neutrophil chemokines and matrix metalloproteinase-1 in human uterine smooth muscle cells.

PubMed

Zhao, Yin; Koga, Kaori; Osuga, Yutaka; Izumi, Gentaro; Takamura, Masashi; Harada, Miyuki; Hirata, Tetsuya; Hirota, Yasushi; Yoshino, Osamu; Fujii, Tomoyuki; Kozuma, Shiro

2013-03-01

The aim of this study was to investigate the impact of uterine contraction on the immune environment within the uterus during parturition. Uterine smooth muscle cells (USMC) were isolated from uterine myometrial tissues and cultured. The effects of cyclic stretch on mRNA and/or protein expression of IL-8, Groα, and pro-MMP-1 by USMC were measured using RT-PCR and ELISA. Neutrophil chemotactic activity in conditioned media was evaluated using migration assays. To evaluate the effect of progesterone (P(4) ), USMC were pretreated with P(4) for 24 hr. Cyclic stretch increased IL-8 and Groα mRNA and protein and pro-MMP-1 production significantly. Supernatants from stretched cells induced neutrophil chemotactic activity significantly; these effects were abrogated by anti-IL-8 or Groα neutralizing antibodies. Stretch effects were reduced by P(4) . These results suggest that uterine contraction may induce neutrophil infiltration and MMP-1 production, which may contribute to cervical ripening and rupture of membrane. The inhibitory effects of P(4) may explain the mechanism by which progestin prevents preterm labor. © 2012 John Wiley & Sons A/S.

Chemotaxis of C. elegans in 3D media: a model for navigation of undulatory microswimmers

NASA Astrophysics Data System (ADS)

Patel, Amar; Bilbao, Alejandro; Rahman, Mizanur; Vanapalli, Siva; Blawzdziewicz, Jerzy

2017-11-01

While the natural environment of C. elegans consists of complex 3D media (e.g., decomposing organic matter and water), most studies of chemotactic behavior of this nematode are limited to 2D. We present a 3D chemotaxis model that combines a realistic geometrical representation of body movements associated with 3D maneuvers, an analysis of mechanical interactions of the nematode body with the surrounding medium to determine nematode trajectories, and a simple memory-function description of chemosensory apparatus that controls the frequency, magnitude, and timing of turning maneuvers. We show that two main chemotaxis strategies of C. elegans moving in 2D, i.e., the biased random walk and gradual turn, are effective also in 3D, provided that 2D turns are supplemented by the roll maneuvers that enable 3D reorientation. Optimal choices of chemosensing and gait-control parameters are discussed; we show that the nematode can maintain efficient chemotaxis in burrowing and swimming by adjusting the undulation frequency alone, without changing the chemotactic component of the body control. Understanding how C. elegans efficiently navigates in 3D media may help in developing self-navigating artificial microswimmers. Supported by NSF Grant No. CBET 1603627.

Impact of motility and chemotaxis features of the rhizobacterium Pseudomonas chlororaphis PCL1606 on its biocontrol of avocado white root rot.

PubMed

Polonio, Álvaro; Vida, Carmen; de Vicente, Antonio; Cazorla, Francisco M

2017-06-01

The biocontrol rhizobacterium Pseudomonas chlororaphis PCL1606 has the ability to protect avocado plants against white root rot produced by the phytopathogenic fungus Rosellinia necatrix. Moreover, PCL1606 displayed direct interactions with avocado roots and the pathogenic fungus. Thus, nonmotile (flgK mutant) and non-chemotactic (cheA mutant) derivatives of PCL1606 were constructed to emphasize the importance of motility and chemotaxis in the biological behaviour of PCL1606 during the biocontrol interaction. Plate chemotaxis assay showed that PCL1606 was attracted to the single compounds tested, such as glucose, glutamate, succinate, aspartate and malate, but no chemotaxis was observed to avocado or R. necatrix exudates. Using the more sensitive capillary assay, it was reported that smaller concentrations (1 mM) of single compounds elicited high chemotactic responses, and strong attraction was confirmed to avocado and R. necatrix exudates. Finally, biocontrol experiments revealed that the cheA and fglK derivative mutants reduced root protection against R. necatrix, suggesting an important role for these biological traits in biocontrol by P. chlororaphis PCL1606. [Int Microbiol 20(2):94-104 (2017)]. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

The actin cytoskeleton of chemotactic amoebae operates close to the onset of oscillations

NASA Astrophysics Data System (ADS)

Westendorf, Christian; Negrete, Jose, Jr.; Bae, Albert; Sandmann, Rabea; Bodenschatz, Eberhard; Beta, Carsten

2013-03-01

We report evidence that the actin machinery of chemotactic Dictyostelium cells operates close to an oscillatory instability. The averaged F-actin response of many cells to a short-time pulse of cAMP is reminiscent of a damped oscillation. At the single-cell level, however, the response dynamics ranged from short, strongly damped responses to slowly decaying, weakly damped oscillations. Furthermore, in a small subpopulation, we observed self-sustained oscillations in the cortical F-actin concentration. We systematically exposed a large number of cells to periodic pulse trains. The results indicate a resonance peak at periodic inputs of around 20 s. We propose a delayed feedback model that explains our experimental findings based on a time-delay in the actin regulatory network. To quantitatively test the model, we performed stimulation experiments with cells that express GFP-tagged fusion proteins of Coronin and Aip1. These served as markers of the F-actin disassembly process and thus allow us to estimate the delay time. Based on this independent estimate, our model predicts an intrinsic period of 20 s, which agrees with the resonance observed experimentally. Financial support by the Max-Planck Society and the DFG (SFB 937).

Essential role of protein kinase C zeta in transducing a motility signal induced by superoxide and a chemotactic peptide, fMLP.

PubMed

Kuribayashi, Kageaki; Nakamura, Kiminori; Tanaka, Maki; Sato, Tsutomu; Kato, Junji; Sasaki, Katsunori; Takimoto, Rishu; Kogawa, Katsuhisa; Terui, Takeshi; Takayama, Tetsuji; Onuma, Takayuki; Matsunaga, Takuya; Niitsu, Yoshiro

2007-03-26

Under various pathological conditions, including infection, malignancy, and autoimmune diseases, tissues are incessantly exposed to reactive oxygen species produced by infiltrating inflammatory cells. We show augmentation of motility associated with morphological changes of human squamous carcinoma SASH1 cells, human peripheral monocytes (hPMs), and murine macrophage-like cell line J774.1 by superoxide stimulation. We also disclose that motility of hPMs and J774.1 induced by a chemotactic peptide (N-formyl-methionyl-leucyl-phenylalanine [fMLP]) was inhibited by superoxide dismutase or N-acetylcystein, indicating stimulation of motility by superoxide generated by fMLP stimulation. In these cells, protein kinase C (PKC) zeta was activated to phosphorylate RhoGDI-1, which liberated RhoGTPases, leading to their activation. These events were inhibited by dominant-negative PKCzeta in SASH1 cells, myristoylated PKCzeta peptides in hPMs and J774.1, or a specific inhibitor of RhoGTPase in SASH1, hPMs, and J774.1. These results suggest a new approach for manipulation of inflammation as well as tumor cell invasion by targeting this novel signaling pathway.

Essential role of protein kinase C ζ in transducing a motility signal induced by superoxide and a chemotactic peptide, fMLP

PubMed Central

Kuribayashi, Kageaki; Nakamura, Kiminori; Tanaka, Maki; Sato, Tsutomu; Kato, Junji; Sasaki, Katsunori; Takimoto, Rishu; Kogawa, Katsuhisa; Terui, Takeshi; Takayama, Tetsuji; Onuma, Takayuki; Matsunaga, Takuya; Niitsu, Yoshiro

2007-01-01

Under various pathological conditions, including infection, malignancy, and autoimmune diseases, tissues are incessantly exposed to reactive oxygen species produced by infiltrating inflammatory cells. We show augmentation of motility associated with morphological changes of human squamous carcinoma SASH1 cells, human peripheral monocytes (hPMs), and murine macrophage-like cell line J774.1 by superoxide stimulation. We also disclose that motility of hPMs and J774.1 induced by a chemotactic peptide (N-formyl-methionyl-leucyl-phenylalanine [fMLP]) was inhibited by superoxide dismutase or N-acetylcystein, indicating stimulation of motility by superoxide generated by fMLP stimulation. In these cells, protein kinase C (PKC) ζ was activated to phosphorylate RhoGDI-1, which liberated RhoGTPases, leading to their activation. These events were inhibited by dominant-negative PKCζ in SASH1 cells, myristoylated PKCζ peptides in hPMs and J774.1, or a specific inhibitor of RhoGTPase in SASH1, hPMs, and J774.1. These results suggest a new approach for manipulation of inflammation as well as tumor cell invasion by targeting this novel signaling pathway. PMID:17389234

Neutrophil formyl-peptide receptors. Relationship to peptide-induced responses and emphysema.

PubMed

Stockley, R A; Grant, R A; Llewellyn-Jones, C G; Hill, S L; Burnett, D

1994-02-01

A reproducible assay was established to assess the number of formyl-peptide receptors expressed on the surface of human polymorphonuclear leukocytes (PMN). Using this assay the number of receptors was shown to demonstrate wide within- and between-subject variability. However, the receptor numbers were related to the chemotactic response (r = 0.572) and degranulation response (r = 0.512) to the peptide formyl-methionyl-leucyl-phenylalanine. Subsequent studies showed increased receptor numbers on PMN from patients with emphysema (median, 459 x 10(3)/cell; range, 207 to 1,080) as compared with age-matched control subjects (median, 288; range, 168 to 519; p < 0.02), which may explain the increased chemotactic response of the PMN to formyl peptides. This difference was not observed in patients with bronchiectasis, suggesting that the increased receptor number is a feature of emphysema. Furthermore, the increase was largely a feature of smokers with emphysema (median, 463; range, 362 to 1,080), whereas age-matched smokers without emphysema had lower numbers of receptors (p < 0.001; median, 332; range, 243 to 411). This observation suggests a mechanism that may explain the susceptibility of some smokers to the development of emphysema.

Bacteria of leg atheromatous arteries responsible for inflammation.

PubMed

Olszewski, Waldemar Lech; Rutkowska, Joanna; Moscicka-Wesolowska, Maria; Swoboda-Kopec, Ewa; Stelmach, Ewa; Zaleska, Marzanna; Zagozda, Malgorzata

2016-09-01

Ischaemia of the lower limbs is frequently followed by inflammation and, in advanced cases, necrosis of peripheral tissues. Whether this is caused by arterial hypoperfusion only or by the presence of bacteria in the arterial walI as well remains unclear. The aim of the study was to prove the presence and source of bacteria in arterial specimens and evaluate their chemotactic properties resulting in the formation of periarterial cellular infiltrates. Bacterial culture and testing for 16sRNA were performed in fragments of popliteal artery harvested from amputated limbs. Carotid artery plaques served as controls. Fragments of arteries were transplanted into scid mice to evaluate their chemotactic activity for macrophages. a) higher prevalence of isolates and 16sRNA in atherosclerotic popliteal than carotid arteries, b) high density of plaque and periarterial infiltrates and mRNA level for pro-inflammatory cytokines in popliteal arteries, c) prevalent microbes were Staphylococcus aureus, S. epidermidis and Enterococci, d) foot skin and arterial bacterial phenotypes and DNA revealed evident similarities, and e) more intensive mouse macrophage accumulation in popliteal than carotid implants into scid mice. The presence of bacteria in the lower limb arterial wall was documented. They may predispose to inflammation secondary to ischaemic changes.

Intracellular calcium rise is not a necessary step for the stimulated actin polymerization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yassin, R.

1986-03-01

Stimulation of rabbit peritoneal neutrophils by many chemotactic (formyl Methionyl-Leucyl-Phenylalanine (fMLP), Leukotriene B/sub 4/ (LTB/sub 4/)) and non-chemotactic (phorbol 12-myristate, 13-acetate (PMA), platelet activating factor (PAF), and the calcium ionophore A23187) factors produces rapid and dose dependent increases in the amount of actin associated with the cytoskeleton. The stimulated increase in cytoskeletal actin does not appear to require a rise in the intracellular concentration of free calcium. The increase in cytoskeletal actin produced by A23187 is transient and does not depend on the presence of calcium in the suspending medium. In the presence of extracellular calcium, the effect of themore » ionophore is biphasic with respect to concentration. The increases in actin association with cytoskeletal produced by fMLP, LTB/sub 4/, and A23187 but not by PMA, are inhibited by hyperosmolarity and pertussis toxin pretreatment. On the other hand, the addition of hyperosmolarity or pertussis toxin has small effect on the rise in the intracellular calcium produced by A23187. The results presented here suggest that an increase in the intracellular concentration of free calcium is not necessary for the stimulated increases in cytoskeletal actin.« less

Oxysterol-EBI2 signaling in immune regulation and viral infection.

PubMed

Daugvilaite, Viktorija; Arfelt, Kristine Niss; Benned-Jensen, Tau; Sailer, Andreas W; Rosenkilde, Mette M

2014-07-01

The seven transmembrane G protein-coupled receptor Epstein-Barr virus (EBV) induced gene 2 (EBI2; also known as GPR183) was identified in 1993 on the basis of its substantial upregulation in EBV-infected cells. It is primarily expressed in lymphoid cells; most abundantly in B cells. EBI2 is central for the positioning of B cells within the lymphoid organs, a process that is regulated in part by a chemotactic gradient formed by the endogenous lipid agonists, and in part by a fine-tuned regulation of EBI2 cell surface expression. The most potent endogenous EBI2 agonist is 7α, 25-dihydroxyxcholesterol (7α,25-OHC), yet many structurally related oxysterols can bind to an EBI2 pocket that is defined by the upper parts of the transmembrane helices and extracellular receptor regions. EBI2 signals via Gαi, as well as via G protein-independent pathways like β-arrestin recruitment. The concerted action of these pathways leads to cell migration. By genetically interfering with its up- and downregulation, EBI2 was also recently shown to induce cell proliferation, an action that could be inhibited by small molecule antagonists. Here, we focus on the oxysterol-EBI2 axis in immune control, including its role in the EBV life cycle. We also summarize the structural and functional properties of EBI2 interaction with oxysterol agonists and small molecule antagonists and discuss EBI2 as therapeutic target for diseases of the immune system. © 2014 The Authors. European Journal of Immunology published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Dictyostelium mutant deficient in severin, an F-actin fragmenting protein, shows normal motility and chemotaxis

PubMed Central

1989-01-01

A severin deficient mutant of Dictyostelium discoideum has been isolated by the use of colony immunoblotting after chemical mutagenesis. In homogenates of wild-type cells, severin is easily detected as a very active F-actin fragmenting protein. Tests for severin in the mutant, HG1132, included viscometry for the assay of F- actin fragmentation in fractions from DEAE-cellulose columns, labeling of blots with monoclonal and polyclonal antibodies, and immunofluorescent-labeling of cryosections. Severin could not be detected in the mutant using these methods. The mutation in HG1132 is recessive and has been mapped to linkage group VII. The mutant failed to produce the normal severin mRNA, but small amounts of a transcript that was approximately 100 bases larger than the wild-type mRNA were detected in the mutant throughout all stages of development. On the DNA level a new Mbo II restriction site was found in the mutant within the coding region of the severin gene. The severin deficient mutant cells grew at an approximately normal rate, aggregated and formed fruiting bodies with viable spores. By the use of an image processing system, speed of cell movement, turning rates, and precision of chemotactic orientation in a stable gradient of cyclic AMP were quantitated, and no significant differences between wild-type and mutant cells were found. Thus, under the culture conditions used, severin proved to be neither essential for growth of D. discoideum nor for any cell function that is important for aggregation or later development. PMID:2537840

Galectin-3 maintains cell motility from the subventricular zone to the olfactory bulb

PubMed Central

Comte, Isabelle; Kim, Yongsoo; Young, Christopher C.; van der Harg, Judith M.; Hockberger, Philip; Bolam, Paul J.; Poirier, Françoise; Szele, Francis G.

2011-01-01

The adult brain subventricular zone (SVZ) produces neuroblasts that migrate through the rostral migratory stream (RMS) to the olfactory bulb (OB) in a specialized niche. Galectin-3 (Gal-3) regulates proliferation and migration in cancer and is expressed by activated macrophages after brain injury. The function of Gal-3 in the normal brain is unknown, but we serendipitously found that it was expressed by ependymal cells and SVZ astrocytes in uninjured mice. Ependymal cilia establish chemotactic gradients and astrocytes form glial tubes, which combine to aid neuroblast migration. Whole-mount preparations and electron microscopy revealed that both ependymal cilia and SVZ astrocytes were disrupted in Gal3−/− mice. Interestingly, far fewer new BrdU+ neurons were found in the OB of Gal3−/− mice, than in wild-type mice 2 weeks after labeling. However, SVZ proliferation and cell death, as well as OB differentiation rates were unaltered. This suggested that decreased migration in vivo was sufficient to decrease the number of new OB neurons. Two-photon time-lapse microscopy in forebrain slices confirmed decreased migration; cells were slower and more exploratory in Gal3−/− mice. Gal-3 blocking antibodies decreased migration and dissociated neuroblast cell–cell contacts, whereas recombinant Gal-3 increased migration from explants. Finally, we showed that expression of phosphorylated epidermal growth factor receptor (EGFR) was increased in Gal3−/− mice. These results suggest that Gal-3 is important in SVZ neuroblast migration, possibly through an EGFR-based mechanism, and reveals a role for this lectin in the uninjured brain. PMID:21693585

A homologous form of human interleukin 16 is implicated in microglia recruitment following nervous system injury in leech Hirudo medicinalis.

PubMed

Croq, Françoise; Vizioli, Jacopo; Tuzova, Marina; Tahtouh, Muriel; Sautiere, Pierre-Eric; Van Camp, Christelle; Salzet, Michel; Cruikshank, William W; Pestel, Joel; Lefebvre, Christophe

2010-11-01

In contrast to mammals, the medicinal leech Hirudo medicinalis can completely repair its central nervous system (CNS) after injury. This invertebrate model offers unique opportunities to study the molecular and cellular basis of the CNS repair processes. When the leech CNS is injured, microglial cells migrate and accumulate at the site of lesion, a phenomenon known to be essential for the usual sprouting of injured axons. In the present study, we demonstrate that a new molecule, designated HmIL-16, having functional homologies with human interleukin-16 (IL-16), has chemotactic activity on leech microglial cells as observed using a gradient of human IL-16. Preincubation of microglial cells either with an anti-human IL-16 antibody or with anti-HmIL-16 antibody significantly reduced microglia migration induced by leech-conditioned medium. Functional homology was demonstrated further by the ability of HmIL-16 to promote human CD4+ T cell migration which was inhibited by antibody against human IL-16, an IL-16 antagonist peptide or soluble CD4. Immunohistochemistry of leech CNS indicates that HmIL-16 protein present in the neurons is rapidly transported and stored along the axonal processes to promote the recruitment of microglial cells to the injured axons. To our knowledge, this is the first identification of a functional interleukin-16 homologue in invertebrate CNS. The ability of HmIL-16 to recruit microglial cells to sites of CNS injury suggests a role for HmIL-16 in the crosstalk between neurons and microglia in the leech CNS repair.

Integration of the Second Messenger c-di-GMP into the Chemotactic Signaling Pathway

PubMed Central

Russell, Matthew H.; Bible, Amber N.; Fang, Xin; Gooding, Jessica R.; Campagna, Shawn R.; Gomelsky, Mark; Alexandre, Gladys

2013-01-01

ABSTRACT Elevated intracellular levels of the bacterial second messenger c-di-GMP are known to suppress motility and promote sessility. Bacterial chemotaxis guides motile cells in gradients of attractants and repellents over broad concentration ranges, thus allowing bacteria to quickly adapt to changes in their surroundings. Here, we describe a chemotaxis receptor that enhances, as opposed to suppresses, motility in response to temporary increases in intracellular c-di-GMP. Azospirillum brasilense’s preferred metabolism is adapted to microaerophily, and these motile cells quickly navigate to zones of low oxygen concentration by aerotaxis. We observed that changes in oxygen concentration result in rapid changes in intracellular c-di-GMP levels. The aerotaxis and chemotaxis receptor, Tlp1, binds c-di-GMP via its C-terminal PilZ domain and promotes persistent motility by increasing swimming velocity and decreasing swimming reversal frequency, which helps A. brasilense reach low-oxygen zones. If c-di-GMP levels remain high for extended periods, A. brasilense forms nonmotile clumps or biofilms on abiotic surfaces. These results suggest that association of increased c-di-GMP levels with sessility is correct on a long-term scale, while in the short-term c-di-GMP may actually promote, as opposed to suppress, motility. Our data suggest that sensing c-di-GMP by Tlp1 functions similar to methylation-based adaptation. Numerous chemotaxis receptors contain C-terminal PilZ domains or other sensory domains, suggesting that intracellular c-di-GMP as well as additional stimuli can be used to modulate adaptation of bacterial chemotaxis receptors. PMID:23512960

Chemotaxis and adherence to fungal surfaces are key components of the behavioral response of Burkholderia terrae BS001 to two selected soil fungi.

PubMed

Haq, Irshad Ul; Calixto, Renata Oliveira da Rocha; Yang, Pu; Dos Santos, Giulia Maria Pires; Barreto-Bergter, Eliana; van Elsas, Jan Dirk

2016-11-01

Burkholderia terrae BS001 has previously been proposed to be a 'generalist' associate of soil fungi, but its strategies of interaction have been largely ignored. Here, we studied the chemotactic behavior of B. terrae BS001 towards Lyophyllum sp. strain Karsten and Trichoderma asperellum 302 and the role of fungal surface molecules in their physical interaction with the bacteria. To assess the involvement of the type 3 secretion system (T3SS), wild-type strain BS001 and T3SS mutant strain BS001-ΔsctD were used in the experiments. First, the two fungi showed divergent behavior when confronted with B. terrae BS001 on soil extract agar medium. Lyophyllum sp. strain Karsten revealed slow growth towards the bacterium, whereas T. asperellum 302 grew avidly over it. Both on soil extract and M9 agar, B. terrae BS001 and BS001-ΔsctD moved chemotactically towards the hyphae of both fungi, with a stronger response to Lyophyllum sp. strain Karsten than to T. asperellum 302. The presence of a progressively increasing glycerol level in the M9 agar enhanced the level of movement. Different oxalic acid concentrations exerted varied effects, with a significantly raised chemotactic response at lower, and a subdued response at higher concentrations. Testing of the adherence of B. terrae BS001 and BS001-ΔsctD to Lyophyllum sp. strain Karsten and to cell envelope-extracted ceramide monohexosides (CMHs) revealed that CMHs in both conidia and hyphae could bind strain BS001 cells. As BS001-ΔsctD adhered significantly less to the CMHs than BS001, the T3SS was presumed to have a role in the interaction. In contrast, such avid adherence was not detected with T. asperellum 302. Thus, B. terrae BS001 shows a behavior characterized by swimming towards Lyophyllum sp. strain Karsten and T. asperellum 302 and attachment to the CMH moiety in the cell envelope, in particular of the former. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Chemotaxis of nurse shark leukocytes.

PubMed

Obenauf, S D; Smith, S H

1985-01-01

Studies were conducted to determine the ability of leukocytes from the nurse shark to migrate in an in vitro micropore filter chemotaxis assay and to determine optimal assay conditions and suitable attractants for such an assay. A migratory response was seen with several attractants: activated rat serum, activated shark plasma, and a pool of shark complement components. Only the response to activated rat serum was chemotactic, as determined by the checkerboard assay.

Platelet-Derived Growth Factor in the Ovarian Follicle Attracts the Stromal Cells of the Fallopian Tube Fimbriae

PubMed Central

Chen, Chiu-Hua; Hsu, Che-Fang; Huang, Rui-Len; Ding, Dah-Ching; Chu, Tang-Yuan

2016-01-01

During human ovulation, the fallopian tube fimbriae must move to the ovulation site to catch the oocyte. As the tissue-of-origin of the majority of ovarian high-grade serous carcinoma (HGSC), the fallopian tube fimbriae carrying a precursor cancer lesion may also approach the ovulatory site for metastasis. We hypothesize that platelet-derived growth factor (PDGF) in mature follicle fluid (FF) attracts the migration of PDGFR-expressing fimbriae toward the ovulating follicle. We observed that more PDGFR-β was expressed in the distal part than in the proximal parts of the fallopian tube, particularly in stromal cells in the lamina propria. The stromal cells, but not the epithelial cells, from normal fimbriae and fallopian tube HGSC were highly chemotactic to mature FF. The chemotactic activities were positively correlated with PDGF-BB and estradiol levels in FF and were abolished by a blocking antibody of PDGFR-β and by tyrosine kinase inhibitor imatinib. When PDGF-BB/AB was depleted from the FF, more than 80% of chemotaxis activities were diminished. This study suggests an ovarian follicle-directed and PDGF-dependent attraction of fallopian tube fimbriae before ovulation. The same mechanism may also be crucial for the ovarian homing of HGSC, which largely originates in the fimbriae. PMID:27379403

Anethole and eugenol reduce in vitro and in vivo leukocyte migration induced by fMLP, LTB4, and carrageenan.

PubMed

Estevão-Silva, Camila Fernanda; Kummer, Raquel; Fachini-Queiroz, Fernanda Carolina; Grespan, Renata; Nogueira de Melo, Gessilda Alcântara; Baroni, Silmara; Cuman, Roberto Kenji Nakamura; Bersani-Amado, Ciomar Aparecida

2014-07-01

The aim of this study was to investigate the effect of anethole (AN) and eugenol (EUG) on leukocyte migration using in vitro chemotaxis and in situ microcirculation assays. BALB/c mice were used for the in vitro chemotaxis assay, and Wistar rats for the in situ microcirculation assay. We evaluated (a) the in vitro leukocyte migration in response to chemotactic factors (formyl-methionyl-leucyl-phenylalanine [fMLP] and leukotriene B4 [LTB4]) and (b) the rolling, adhesion, and migration of leukocytes induced by an injection of carrageenan (100 µg/cavity) into the scrotum of the animal. In the in vitro chemotaxis assay, AN and EUG at doses of 1, 3, 9, and 27 µg/ml significantly inhibited leukocyte migration when stimulated by the chemotactic agents fMLP and LTB4. In the in situ microcirculation assay, AN at doses of 125 and 250 mg/kg and EUG at a dose of 250 mg/kg significantly decreased the number of leukocytes that rolled, adhered, and migrated to perivascular tissue. The results indicate that AN and EUG exert inhibitory effects on leukocyte migration, highlighting their possible use to diminish excessive leukocyte migration in the inflammatory process.

Chemotaxis of primitive hematopoietic cells in response to stromal cell–derived factor-1

PubMed Central

Jo, Deog-Yeon; Rafii, Shahin; Hamada, Tsuneyoshi; Moore, Malcolm A.S.

2000-01-01

Stromal cell–derived factor-1 (SDF-1) provides a potent chemotactic stimulus for CD34+ hematopoietic cells. We cultured mobilized peripheral blood (PB) and umbilical cord blood (CB) for up to 5 weeks and examined the migratory activity of cobblestone area–forming cells (CAFCs) and long-term culture–initiating cells (LTC-ICs) in a transwell assay. In this system, SDF-1 or MS-5 marrow stromal cells placed in the lower chamber induced transmembrane and transendothelial migration by 2- and 5-week-old CAFCs and LTC-ICs in 3 hours. Transmigration was blocked by preincubation of input CD34+ cells with antibody to CXCR4. Transendothelial migration of CB CAFCs and LTC-ICs was higher than that of PB. We expanded CD34+ cells from CB in serum-free medium with thrombopoietin, flk-2 ligand, and c-kit ligand, with or without IL-3 and found that CAFCs cultured in the absence of IL-3 had a chemotactic response equivalent to noncultured cells, even after 5 weeks. However, addition of IL-3 to the culture reduced this response by 20–50%. These data indicate that SDF-1 induces chemotaxis of primitive hematopoietic cells signaling through CXCR4 and that the chemoattraction could be downmodulated by culture ex vivo. PMID:10619866

Factor Associated with Neutral Sphingomyelinase Activity Mediates Navigational Capacity of Leukocytes Responding to Wounds and Infection: Live Imaging Studies in Zebrafish Larvae

PubMed Central

Boecke, Alexandra; Sieger, Dirk; Neacsu, Cristian Dan; Kashkar, Hamid

2012-01-01

Factor associated with neutral sphingomyelinase activity (FAN) is an adaptor protein that specifically binds to the p55 receptor for TNF (TNF-RI). Our previous investigations demonstrated that FAN plays a role in TNF-induced actin reorganization by connecting the plasma membrane with actin cytoskeleton, suggesting that FAN may impact on cellular motility in response to TNF and in the context of immune inflammatory conditions. In this study, we used the translucent zebrafish larvae for in vivo analysis of leukocyte migration after morpholino knockdown of FAN. FAN-deficient zebrafish leukocytes were impaired in their migration toward tail fin wounds, leading to a reduced number of cells reaching the wound. Furthermore, FAN-deficient leukocytes show an impaired response to bacterial infections, suggesting that FAN is generally required for the directed chemotactic response of immune cells independent of the nature of the stimulus. Cell-tracking analysis up to 3 h after injury revealed that the reduced number of leukocytes is not due to a reduction in random motility or speed of movement. Leukocytes from FAN-deficient embryos protrude pseudopodia in all directions instead of having one clear leading edge. Our results suggest that FAN-deficient leukocytes exhibit an impaired navigational capacity, leading to a disrupted chemotactic response. PMID:22802420

Endocrine-immune interactions in human endometrium.

PubMed

Kayisli, U A; Guzeloglu-Kayisli, O; Arici, A

2004-12-01

The immune system is a complex entity designed to eliminate foreign intruding antigens and is influenced by and, in turn, influences the function of the reproductive system. Despite the widespread associations between immunology and reproductive medicine, the study of system interactions remains in its infancy. Many diverse facts are accumulating, and pieces of the puzzle are becoming available to provide a clearer picture. In this review article, we focus on the interactions between endocrine and immune systems in the human endometrium. Understanding the molecular pathways in endocrine-immune interactions in the human endometrium is crucial to understand events such as menstrual bleeding, tissue repair and regeneration, inflammation, angiogenesis, blastocyst implantation, and progression of pregnancy. These events require a balanced regulation of endometrial differentiation, proliferation, cell survival, leukocyte recruitment, apoptosis, and angiogenesis by sex steroids. In this review, we first outline the role of survival factors such as phosphoinositol 3-kinase/protein kinase B, PTEN, NFkappaB, and apoptotic molecules (Fas-FasL, Bcl-2). We then discuss their regulation by estrogen and progesterone in the endometrium. We present evidence for direct and/or indirect roles of steroid hormones on the expression of chemotactic cytokines (interleukin-8 and monocyte chemotactic protein-1) and on the survival versus apoptosis of resident endometrial cells (stromal, epithelial, and endothelial cells) and nonresident cells (leukocytes).

Correlation of interleukin-6 and monocyte chemotactic protein-1 concentrations with crescent formation and myeloperoxidase-specific anti-neutrophil cytoplasmic antibody titer in SCG/Kj mice by treatment with anti-interleukin-6 receptor antibody or mizoribine.

PubMed

Nagao, Tomokazu; Kusunoki, Reina; Iwamura, Chiaki; Kobayashi, Shigeto; Yumura, Wako; Kameoka, Yosuke; Nakayama, Toshinori; Suzuki, Kazuo

2013-09-01

Myeloperoxidase-specific anti-neutrophil cytoplasmic antibody (MPO-ANCA) is associated with rapidly progressive glomerulonephritis (RPGN) and glomerular crescent formation. Pathogenic factors in RPGN were analyzed by using SCG/Kj mice, which spontaneously develop MPO-ANCA-associated RPGN. The serum concentration of soluble IL-6R was determined by using ELISA and those of another 23 cytokines and chemokines by Bio-Plex analysis. Sections of frozen kidney tissue were examined by fluorescence microscopy and the CD3(+) B220(+) T cell subset in the spleen determined by a flow cytometry. Concentrations of IL-6 and monocyte chemotactic protein-1 were significantly correlated with the percentages of crescent formation. Anti-IL-6R antibody, which has been effective in patients with rheumatoid arthritis, was administered to SCG/Kj mice to elucidate the role of IL-6 in the development of RPGN. MPO-ANCA titers decreased after administration of anti-IL-6R antibody, but not titers of mizoribine, which is effective in Kawasaki disease model mice. These results suggest that IL-6-mediated signaling is involved in the production of MPO-ANCA. © 2013 The Societies and Wiley Publishing Asia Pty Ltd.

Investigations into the design principles in the chemotactic behavior of Escherichia coli.

PubMed

Kim, Tae-Hwan; Jung, Sung Hoon; Cho, Kwang-Hyun

2008-01-01

Inspired by the recent studies on the analysis of biased random walk behavior of Escherichia coli[Passino, K.M., 2002. Biomimicry of bacterial foraging for distributed optimization and control. IEEE Control Syst. Mag. 22 (3), 52-67; Passino, K.M., 2005. Biomimicry for Optimization, Control and Automation. Springer-Verlag, pp. 768-798; Liu, Y., Passino, K.M., 2002. Biomimicry of social foraging bacteria for distributed optimization: models, principles, and emergent behaviors. J. Optim. Theory Appl. 115 (3), 603-628], we have developed a model describing the motile behavior of E. coli by specifying some simple rules on the chemotaxis. Based on this model, we have analyzed the role of some key parameters involved in the chemotactic behavior to unravel the underlying design principles. By investigating the target tracking capability of E. coli in a maze through computer simulations, we found that E. coli clusters can be controlled as target trackers in a complex micro-scale-environment. In addition, we have explored the dynamical characteristics of this target tracking mechanism through perturbation of parameters under noisy environments. It turns out that the E. coli chemotaxis mechanism might be designed such that it is sensitive enough to efficiently track the target and also robust enough to overcome environmental noises.

3D simulations of early blood vessel formation

NASA Astrophysics Data System (ADS)

Cavalli, F.; Gamba, A.; Naldi, G.; Semplice, M.; Valdembri, D.; Serini, G.

2007-08-01

Blood vessel networks form by spontaneous aggregation of individual cells migrating toward vascularization sites (vasculogenesis). A successful theoretical model of two-dimensional experimental vasculogenesis has been recently proposed, showing the relevance of percolation concepts and of cell cross-talk (chemotactic autocrine loop) to the understanding of this self-aggregation process. Here we study the natural 3D extension of the computational model proposed earlier, which is relevant for the investigation of the genuinely three-dimensional process of vasculogenesis in vertebrate embryos. The computational model is based on a multidimensional Burgers equation coupled with a reaction diffusion equation for a chemotactic factor and a mass conservation law. The numerical approximation of the computational model is obtained by high order relaxed schemes. Space and time discretization are performed by using TVD schemes and, respectively, IMEX schemes. Due to the computational costs of realistic simulations, we have implemented the numerical algorithm on a cluster for parallel computation. Starting from initial conditions mimicking the experimentally observed ones, numerical simulations produce network-like structures qualitatively similar to those observed in the early stages of in vivo vasculogenesis. We develop the computation of critical percolative indices as a robust measure of the network geometry as a first step towards the comparison of computational and experimental data.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, G.E.

When intact Arbacia punctulata spermatozoa are exposed to solubilized egg jelly, the electrophoretic mobility of an abundant sperm flagellar membrane protein changes from an apparent molecular mass of 160 kDa to 150 kDa. A. punctulata spermatozoa can be labeled in vivo with /sup 32/P-labeled cells it was demonstrated that the mobility shift of the 160-kDa protein is due to dephosphorylation. The peptide resact (Cys-Val-Thr-Gly-Ala-Pro-Gly-Cys-Val-Gly-Gly-Gly-Arg-Leu-NH/sub 2/) is the component of egg jelly which is responsible for inducing the dephosphorylation. The 160/150-kdal sperm membrane protein has been purified to homogeneity by affinity chromatography on concanavalin A-agarose, and identified as sperm guanylate cyclase.more » The enzymatic activity of the guanylate cyclase is tightly coupled to its phosphorylation state. Resact has been shown to act as a potent chemoattractant for A. punctulata spermatozoa. The chemotactic response is concentration-dependent, is abolished by pretreatment of the spermatozoa with resact, and shows an absolute requirement for external calcium. This work represents the first demonstration of animal sperm chemotaxis in response to a precisely-defined molecule of egg origin. The results established a new, biologically meaningful function for resact, and may implicate sperm guanylate cyclase and cGMP in flagellar function and the chemotactic response.« less

Elucidation of Distinct Roles of Guinea Pig CXCR1 and CXCR2 in Neutrophil Migration toward IL-8 and GROα by Specific Antibodies.

PubMed

Tanaka, Kento; Yoshitomi, Tomomi; Hirahara, Kazuki

2017-01-01

Chemokine receptors CXCR1 and CXCR2 are conserved between guinea pigs and humans, but the distinct role of each receptor in chemotactic responses of neutrophils against chemokine ligands has not been elucidated due in part to the lack of specific inhibitors against these receptors in guinea pigs. In this study, we investigated the roles of guinea pig CXCR1 and CXCR2 on neutrophils in chemotactic responses to guinea pig interleukin (IL)-8 and growth-regulated oncogene (GRO)α by using specific inhibitory antibodies against these receptors. Neutrophil migration induced by IL-8 was partially inhibited by either anti-CXCR1 antibody or anti-CXCR2 antibody. In addition, the migration was inhibited completely when both anti-CXCR1 and anti-CXCR2 antibodies were combined. On the other hand, neutrophil migration induced by GROα was not inhibited by anti-CXCR1 antibody while inhibited profoundly by anti-CXCR2 antibody. These results indicated that CXCR1 and CXCR2 mediated migration induced by the IL-8 synergistically and only CXCR2 mediated migration induced by GROα in guinea pig neutrophils. Our findings on ligand selectivity of CXCR1 and CXCR2 in guinea pigs are consistent with those in humans.

An Implantable Device for Manipulation of the in vivo Tumor Microenvironment

NASA Astrophysics Data System (ADS)

Williams, James K.

In the past decade, it has become increasingly recognized that interactions between cancer cells and the tumor microenvironment (TME) regulate metastasis. One such interaction is the paracrine loop between macrophages and cancer cells which drives metastatic invasion in mammary tumors. Tumor associated macrophages release epidermal growth factor (EGF), a chemoattractant which induces the migration of cancer cells toward the blood vessels. The cancer cells reciprocate by releasing a macrophage chemoattractant, colony-stimulating factor 1 (CSF-1), resulting in the co-migration of both cell types and subsequent intravasation. In this work, a new technology has been developed for studying the mechanisms by which invasive tumor cells migrate in vivo toward gradients of EGF. Conventional in vitro methods used for studying tumor cell migration lack the complexity found in the TME and are therefore of limited relevance to in vivo metastasis. The Nano Intravital Device (NANIVID) has been designed as an implantable tool to manipulate the TME through the generation of soluble factor gradients. The NANIVID consists of two etched glass substrates, loaded with a hydrogel containing EGF, and sealed together using a polymer membrane. When implanted in vivo, the hydrogel will swell and release the entrapped EGF, forming a diffusion gradient in the tumor over many hours. The NANIVID design has been optimized for use with multiphoton-based intravital imaging, to monitor migration toward the device at single-cell resolution. Stabilization techniques have been developed to minimize imaging artifacts caused by breathing and specimen movement over the course of the experiment. The NANIVID has been validated in vivo using a mouse model of metastasis. When implanted in MDA-MB-231 xenograft tumors grown in SCID mice, chemotaxis of tumor cells was induced by the EGF gradient generated by the device. Cell motility parameters including velocity, directionality, and chemotactic index were calculated by tracking the migrating cells. Many additional chemicals and proteins are compatible with the NANIVID, providing a platform to initiate controlled changes in the TME that were not possible using conventional methods. Additionally, a one-dimensional (1D) cell migration assay was developed using electrospun nanofibers to mimic the collagen fibers associated with invasive breast tumors. Collagen fibers provide a substrate for cancer cells to migrate upon in vivo, serving as a connection to the blood vessels, to promote metastasis. Development of the migration assay enabled a low cost, versatile platform as a model system for the investigation of the motility processes used by tumor cells while constrained to 1D. The following supplemental material was submitted with this work and is available in the online version of this dissertation: Supp. Movie 1. Specimen Drift in Non-Fixtured Tumor.avi; Supp. Movie 2. Specimen Drift in Fixtured Tumor.avi; Supp. Movie 3. MDA-Mb-231 Cell Chemotaxis in vivo Toward 2 uM EGF NANIVID.avi; Supp. Movie 4. MDA-Mb-231 Cell Background Motility- Control NANIVID.avi; Supp. Movie 5. BAC Macrophage Chemotaxis- 300k U-ml hCSF-1 NANIVID.avi; Supp. Movie 6. BAC Macrophage Control Migration.avi; Supp. Movie 7. MTLn3 cells on Nanofiber-PVA Substrates.avi; Supp. Movie 8. MTLn3 cells on Nanofiber-Glass Substrates.avi.

A hybrid discrete-continuum mathematical model of pattern prediction in the developing retinal vasculature.

PubMed

McDougall, S R; Watson, M G; Devlin, A H; Mitchell, C A; Chaplain, M A J

2012-10-01

Pathological angiogenesis has been extensively explored by the mathematical modelling community over the past few decades, specifically in the contexts of tumour-induced vascularisation and wound healing. However, there have been relatively few attempts to model angiogenesis associated with normal development, despite the availability of animal models with experimentally accessible and highly ordered vascular topologies: for example, growth and development of the vascular plexus layers in the murine retina. The current study aims to address this issue through the development of a hybrid discrete-continuum mathematical model of the developing retinal vasculature in neonatal mice that is closely coupled with an ongoing experimental programme. The model of the functional vasculature is informed by a range of morphological and molecular data obtained over a period of several days, from 6 days prior to birth to approximately 8 days after birth. The spatio-temporal formation of the superficial retinal vascular plexus (RVP) in wild-type mice occurs in a well-defined sequence. Prior to birth, astrocytes migrate from the optic nerve over the surface of the inner retina in response to a chemotactic gradient of PDGF-A, formed at an earlier stage by migrating retinal ganglion cells (RGCs). Astrocytes express a variety of chemotactic and haptotactic proteins, including VEGF and fibronectin (respectively), which subsequently induce endothelial cell sprouting and modulate growth of the RVP. The developing RVP is not an inert structure; however, the vascular bed adapts and remodels in response to a wide variety of metabolic and biomolecular stimuli. The main focus of this investigation is to understand how these interacting cellular, molecular, and metabolic cues regulate RVP growth and formation. In an earlier one-dimensional continuum model of astrocyte and endothelial migration, we showed that the measured frontal velocities of the two cell types could be accurately reproduced by means of a system of five coupled partial differential equations (Aubert et al. in Bull. Math. Biol. 73:2430-2451, 2011). However, this approach was unable to generate spatial information and structural detail for the entire retinal surface. Building upon this earlier work, a more realistic two-dimensional hybrid PDE-discrete model is derived here that tracks the migration of individual astrocytes and endothelial tip cells towards the outer retinal boundary. Blood perfusion is included throughout plexus development and the emergent retinal architectures adapt and remodel in response to various biological factors. The resulting in silico RVP structures are compared with whole-mounted retinal vasculatures at various stages of development, and the agreement is found to be excellent. Having successfully benchmarked the model against wild-type data, the effect of transgenic over-expression of various genes is predicted, based on the ocular-specific expression of VEGF-A during murine development. These results can be used to help inform future experimental investigations of signalling pathways in ocular conditions characterised by aberrant angiogenesis.

Effect of HSP27 on Human Breast Tumor Cell Growth and Motility

DTIC Science & Technology

1999-08-01

the small stress protein, HSP27 , on growth and motility characteristics of normal and tumor-derived human mammary cell lines. We hypothesized that...cells overexpressing HSP27 would show increased motility, altered chemotactic properties, increased resistance to heat killing and to certain drugs...Donna has prepared and studied 19 clonal MDA23 1 breast tumor cell lines that overexpress human HSP27 , and determined that, while heat resistance is

Human Platelets Exhibit Chemotaxis using Functional N-Formyl Peptide Receptors

DTIC Science & Technology

2005-01-01

activated phagocytes. Therefore, we examined the chemotactic migration of platelets qualita- tively by videomicroscopy . Platelets in medium were al- lowed...significantly decreased M. Czapiga et al. /Experimental Hematology 33 (2005) 73–84 79Figure 3. Videomicroscopy of human platelets in response to formyl...selected platelets during videomicroscopy from the time of the addition of fMLF (104 M in 1 µL) or PBS. Movement between markers represents 10 frames

Heterogeneity in Neutrophil Microparticles Reveals Distinct Proteome and Functional Properties*

PubMed Central

Dalli, Jesmond; Montero-Melendez, Trinidad; Norling, Lucy V; Yin, Xiaoke; Hinds, Charles; Haskard, Dorian; Mayr, Manuel; Perretti, Mauro

2013-01-01

Altered plasma neutrophil microparticle levels have recently been implicated in a number of vascular and inflammatory diseases, yet our understanding of their actions is very limited. Herein, we investigate the proteome of neutrophil microparticles in order to shed light on their biological actions. Stimulation of human neutrophils, either in suspension or adherent to an endothelial monolayer, led to the production of microparticles containing >400 distinct proteins with only 223 being shared by the two subsets. For instance, postadherent microparticles were enriched in alpha-2 macroglobulin and ceruloplasmin, whereas microparticles produced by neutrophils in suspension were abundant in heat shock 70 kDa protein 1. Annexin A1 and lactotransferrin were expressed in both microparticle subsets. We next determined relative abundance of these proteins in three types of human microparticle samples: healthy volunteer plasma, plasma of septic patients and skin blister exudates finding that these proteins were differentially expressed on neutrophil microparticles from these samples reflecting in part the expression profiles we found in vitro. Functional assessment of the neutrophil microparticles subsets demonstrated that in response to direct stimulation neutrophil microparticles produced reactive oxygen species and leukotriene B4 as well as locomoted toward a chemotactic gradient. Finally, we investigated the actions of the two neutrophil microparticles subsets described herein on target cell responses. Microarray analysis with human primary endothelial cells incubated with either microparticle subset revealed a discrete modulation of endothelial cell gene expression profile. These findings demonstrate that neutrophil microparticles are heterogenous and can deliver packaged information propagating the activation status of the parent cell, potentially exerting novel and fundamental roles both under homeostatic and disease conditions. PMID:23660474

Insights into seven and single transmembrane-spanning domain receptors and their signaling pathways in human natural killer cells.

PubMed

Maghazachi, Azzam A

2005-09-01

Human natural killer (NK) cells are important cells of the innate immune system. These cells perform two prominent functions: the first is recognizing and destroying virally infected cells and transformed cells; the second is secreting various cytokines that shape up the innate and adaptive immune re-sponses. For these cells to perform these activities, they express different sets of receptors. The receptors used by NK cells to extravasate into sites of injury belong to the seven transmembrane (7TM) family of receptors, which characteristically bind heterotrimeric G proteins. These receptors allow NK cells to sense the chemotactic gradients and activate second messengers, which aid NK cells in polarizing and migrating toward the sites of injured tissues. In addition, these receptors determine how and why human resting NK cells are mainly found in the bloodstream, whereas activated NK cells extravasate into inflammatory sites. Receptors for chemokines and lysophospholipids belong to the 7TM family. On the other hand, NK cells recognize invading or transformed cells through another set of receptors that belong to the single transmembrane-spanning domain family. These receptors are either inhibitory or activating. Inhibitory receptors contain the immune receptor tyrosine-based inhibitory motif, and activating receptors belong to either those that associate with adaptor molecules containing the immune receptor tyrosine-based activating motif (ITAM) or those that associate with adaptor molecules containing motifs other than ITAM. This article will describe the nature of these receptors and examine the intracellular signaling pathways induced in NK cells after ligating both types of receptors. These pathways are crucial for NK cell biology, development, and functions.

Carbon Fiber Biocompatibility for Implants

PubMed Central

Petersen, Richard

2016-01-01

Carbon fibers have multiple potential advantages in developing high-strength biomaterials with a density close to bone for better stress transfer and electrical properties that enhance tissue formation. As a breakthrough example in biomaterials, a 1.5 mm diameter bisphenol-epoxy/carbon-fiber-reinforced composite rod was compared for two weeks in a rat tibia model with a similar 1.5 mm diameter titanium-6-4 alloy screw manufactured to retain bone implants. Results showed that carbon-fiber-reinforced composite stimulated osseointegration inside the tibia bone marrow measured as percent bone area (PBA) to a great extent when compared to the titanium-6-4 alloy at statistically significant levels. PBA increased significantly with the carbon-fiber composite over the titanium-6-4 alloy for distances from the implant surfaces of 0.1 mm at 77.7% vs. 19.3% (p < 10−8) and 0.8 mm at 41.6% vs. 19.5% (p < 10−4), respectively. The review focuses on carbon fiber properties that increased PBA for enhanced implant osseointegration. Carbon fibers acting as polymer coated electrically conducting micro-biocircuits appear to provide a biocompatible semi-antioxidant property to remove damaging electron free radicals from the surrounding implant surface. Further, carbon fibers by removing excess electrons produced from the cellular mitochondrial electron transport chain during periods of hypoxia perhaps stimulate bone cell recruitment by free-radical chemotactic influences. In addition, well-studied bioorganic cell actin carbon fiber growth would appear to interface in close contact with the carbon-fiber-reinforced composite implant. Resulting subsequent actin carbon fiber/implant carbon fiber contacts then could help in discharging the electron biological overloads through electrochemical gradients to lower negative charges and lower concentration. PMID:26966555

An Unorthodox Sensory Adaptation Site in the Escherichia coli Serine Chemoreceptor

PubMed Central

Han, Xue-Sheng

2014-01-01

The serine chemoreceptor of Escherichia coli contains four canonical methylation sites for sensory adaptation that lie near intersubunit helix interfaces of the Tsr homodimer. An unexplored fifth methylation site, E502, lies at an intrasubunit helix interface closest to the HAMP domain that controls input-output signaling in methyl-accepting chemotaxis proteins. We analyzed, with in vivo Förster resonance energy transfer (FRET) kinase assays, the serine thresholds and response cooperativities of Tsr receptors with different mutationally imposed modifications at sites 1 to 4 and/or at site 5. Tsr variants carrying E or Q at residue 502, in combination with unmodifiable D and N replacements at adaptation sites 1 to 4, underwent both methylation and demethylation/deamidation, although detection of the latter modifications required elevated intracellular levels of CheB. These Tsr variants could not mediate a chemotactic response to serine spatial gradients, demonstrating that adaptational modifications at E502 alone are not sufficient for Tsr function. Moreover, E502 is not critical for Tsr function, because only two amino acid replacements at this residue abrogated serine chemotaxis: Tsr-E502P had extreme kinase-off output and Tsr-E502I had extreme kinase-on output. These large threshold shifts are probably due to the unique HAMP-proximal location of methylation site 5. However, a methylation-mimicking glutamine at any Tsr modification site raised the serine response threshold, suggesting that all sites influence signaling by the same general mechanism, presumably through changes in packing stability of the methylation helix bundle. These findings are consistent with control of input-output signaling in Tsr through dynamic interplay of the structural stabilities of the HAMP and methylation bundles. PMID:24272777

Downregulation of Heme Oxygenase 1 (HO-1) Activity in Hematopoietic Cells Enhances Their Engraftment After Transplantation.

PubMed

Adamiak, Mateusz; Moore, Joseph B; Zhao, John; Abdelbaset-Ismail, Ahmed; Grubczak, Kamil; Rzeszotek, Sylwia; Wysoczynski, Marcin; Ratajczak, Mariusz Z

2016-01-01

Heme oxygenase 1 (HO-1) is an inducible stress-response enzyme that not only catalyzes the degradation of heme (e.g., released from erythrocytes) but also has an important function in various physiological and pathophysiological states associated with cellular stress, such as ischemic/reperfusion injury. HO-1 has a well-documented anti-inflammatory potential, and HO-1 has been reported to have a negative effect on adhesion and migration of neutrophils in acute inflammation in a model of peritonitis. This finding is supported by our recent observation that hematopoietic stem progenitor cells (HSPCs) from HO-1 KO mice are easy mobilizers, since they respond better to peripheral blood chemotactic gradients than wild-type littermates. Based on these findings, we hypothesized that transient inhibition of HO-1 by nontoxic small-molecule inhibitors would enhance migration of HSPCs in response to bone marrow chemoattractants and thereby facilitate their homing. To directly address this issue, we generated several human hematopoietic cell lines in which HO-1 was upregulated or downregulated. We also exposed murine and human BM-derived cells to small-molecule activators and inhibitors of HO-1. Our results indicate that HO-1 is an inhibitor of hematopoietic cell migration in response to crucial BM homing chemoattractants such as stromal-derived factor 1 (SDF-1) and sphingosine-1-phosphate (S1P). Most importantly, our in vitro and in vivo animal experiments demonstrate for the first time that transiently inhibiting HO-1 activity in HSPCs by small-molecule inhibitors improves HSPC engraftment. We propose that this simple and inexpensive strategy could be employed in the clinical setting to improve engraftment of HSPCs, particularly in those situations in which the number of HSPCs available for transplant is limited (e.g., when transplanting umbilical cord blood).

Barium sulfate micro- and nanoparticles as bioinert reference material in particle toxicology.

PubMed

Loza, Kateryna; Föhring, Isabell; Bünger, Jürgen; Westphal, Götz A; Köller, Manfred; Epple, Matthias; Sengstock, Christina

2016-12-01

The inhalation of particles and their exposure to the bronchi and alveoli constitute a major public health risk. Chemical as well as particle-related properties are important factors for the biological response but are difficult to separate from each other. Barium sulfate is a completely inert chemical compound, therefore it is ideally suited to separate these two factors. The biological response of rat alveolar macrophages (NR8383) was analyzed after exposure to barium sulfate particles with three different diameters (40 nm, 270 nm, and 1.3 μm, respectively) for 24 h in vitro (particle concentrations from 12.5 to 200 μg mL - 1 ). The particles were colloidally stabilized as well as fluorescently-labeled by carboxymethylcellulose, conjugated with 6-aminofluorescein. All kinds of barium sulfate particles were efficiently taken up by NR8383 cells and found inside endo-lysosomes, but never in the cell nucleus. Neither an inflammatory nor a cytotoxic response was detected by the ability of dHL-60 and NR8383 cells to migrate towards a chemotactic gradient (conditioned media of NR8383 cells) and by the release of inflammatory mediators (CCL2, TNF-α, IL-6). The particles neither caused apoptosis (up to 200 μg mL - 1 ) nor necrosis (up to 100 μg mL - 1 ). As only adverse reaction, necrosis was found at a concentration of 200 μg mL - 1 of the largest barium sulfate particles (1.3 μm). Barium sulfate particles are ideally suited as bioinert control to study size-dependent effects such as uptake mechanisms of intracellular distributions of pure particles, especially in nanotoxicology.

Prognostic and Pathogenetic Value of Combining Clinical and Biochemical Indices in Patients With Acute Lung Injury

PubMed Central

Koyama, Tatsuki; Billheimer, D. Dean; Wu, William; Bernard, Gordon R.; Thompson, B. Taylor; Brower, Roy G.; Standiford, Theodore J.; Martin, Thomas R.; Matthay, Michael A.

2010-01-01

Background: No single clinical or biologic marker reliably predicts clinical outcomes in acute lung injury (ALI)/ARDS. We hypothesized that a combination of biologic and clinical markers would be superior to either biomarkers or clinical factors alone in predicting ALI/ARDS mortality and would provide insight into the pathogenesis of clinical ALI/ARDS. Methods: Eight biologic markers that reflect endothelial and epithelial injury, inflammation, and coagulation (von Willebrand factor antigen, surfactant protein D [SP-D]), tumor necrosis factor receptor-1, interleukin [IL]-6, IL-8, intercellular adhesion molecule-1, protein C, plasminogen activator inhibitor-1) were measured in baseline plasma from 549 patients in the ARDSNet trial of low vs high positive end-expiratory pressure. Mortality was modeled with multivariable logistic regression. Predictors were selected using backward elimination. Comparisons between candidate models were based on the receiver operating characteristics (ROC) and tests of integrated discrimination improvement. Results: Clinical predictors (Acute Physiology And Chronic Health Evaluation III [APACHE III], organ failures, age, underlying cause, alveolar-arterial oxygen gradient, plateau pressure) predicted mortality with an area under the ROC curve (AUC) of 0.82; a combination of eight biomarkers and the clinical predictors had an AUC of 0.85. The best performing biomarkers were the neutrophil chemotactic factor, IL-8, and SP-D, a product of alveolar type 2 cells, supporting the concept that acute inflammation and alveolar epithelial injury are important pathogenetic pathways in human ALI/ARDS. Conclusions: A combination of biomarkers and clinical predictors is superior to clinical predictors or biomarkers alone for predicting mortality in ALI/ARDS and may be useful for stratifying patients in clinical trials. From a pathogenesis perspective, the degree of acute inflammation and alveolar epithelial injury are highly associated with the outcome of human ALI/ARDS. PMID:19858233

Motion of particles adhering to the leading lamella of crawling cells

PubMed Central

1981-01-01

Time-lapsed films of particle motion on the leading lamella of chick heart fibroblasts and mouse peritoneal macrophages were analyzed. The particles were composed of powdered glass or powdered aminated polystyrene and were 0.5-1.0 micrometer in radius. Particle motions were described by steps in position from one frame to the time-lapse movies to the next. The statistics of the step-size distribution of the particles were consistent with a particle in Brownian motion subject to a constant force. From the Brownian movement, we have calculated the two-dimensional diffusion coefficient of different particles. These vary by more than an order of magnitude (10(-11)-10(-10) cm2/s) even for particles composed of the same material and located very close to each other on the surface of the cell. This variation was not correlated with particle size but is interpretable as a result of different numbers of adhesive bonds holding the particles to the cells. The constant component of particle movement can be interpreted as a result of a constant force acting on each particle (0.1-1.0 x 10(-8) dyn). Variations in the fractional coefficient for particles close to each other on the cell surface do not yield corresponding differences in velocity, suggesting that the frictional coefficient and the driving force vary together. This is consistent with the hypothesis that the particles are carried by flow of the membrane as a whole or by flow of some submembrane material. The utility of our methods for monitoring cell motile behavior in biologically interesting situations, such as a chemotactic gradient, is discussed. PMID:7309794

Planarian shows decision-making behavior in response to multiple stimuli by integrative brain function.

PubMed

Inoue, Takeshi; Hoshino, Hajime; Yamashita, Taiga; Shimoyama, Seira; Agata, Kiyokazu

2015-01-01

Planarians belong to an evolutionarily early group of organisms that possess a central nervous system including a well-organized brain with a simple architecture but many types of neurons. Planarians display a number of behaviors, such as phototaxis and thermotaxis, in response to external stimuli, and it has been shown that various molecules and neural pathways in the brain are involved in controlling these behaviors. However, due to the lack of combinatorial assay methods, it remains obscure whether planarians possess higher brain functions, including integration in the brain, in which multiple signals coming from outside are coordinated and used in determining behavioral strategies. In the present study, we designed chemotaxis and thigmotaxis/kinesis tracking assays to measure several planarian behaviors in addition to those measured by phototaxis and thermotaxis assays previously established by our group, and used these tests to analyze planarian chemotactic and thigmotactic/kinetic behaviors. We found that headless planarian body fragments and planarians that had specifically lost neural activity following regeneration-dependent conditional gene knockdown (Readyknock) of synaptotagmin in the brain lost both chemotactic and thigmotactic behaviors, suggesting that neural activity in the brain is required for the planarian's chemotactic and thigmotactic behaviors. Furthermore, we compared the strength of phototaxis, chemotaxis, thigmotaxis/kinesis, and thermotaxis by presenting simultaneous binary stimuli to planarians. We found that planarians showed a clear order of predominance of these behaviors. For example, when planarians were simultaneously exposed to 400 lux of light and a chemoattractant, they showed chemoattractive behavior irrespective of the direction of the light source, although exposure to light of this intensity alone induces evasive behavior away from the light source. In contrast, when the light intensity was increased to 800 or 1600 lux and the same dose of chemoattractant was presented, planarian behaviors were gradually shifted to negative phototaxis rather than chemoattraction. These results suggest that planarians may be capable of selecting behavioral strategies via the integration of discrete brain functions when exposed to multiple stimuli. The planarian brain processes external signals received through the respective sensory neurons, thereby resulting in the production of appropriate behaviors. In addition, planarians can adjust behavioral features in response to stimulus conditions by integrating multiple external signals in the brain.

Rapid and Reversible Tubulin Tyrosination in Human Neutrophils Stimulated by the Chemotacted Peptide, fMet Leu-Phe

DTIC Science & Technology

1993-01-01

Ji -Il i H’a ti .. 1 populations oftnaicrotuhbules: ’Ixrosinated dnd iaontirosijnatcdalphlah RothNaivlLs %V , lia~ W.A ,and Mali pli I) li 1 ýil) I I...t11707-Il t720 , dele ateIhaut sec ra’tarv granoarie’ mavi a-� -aagaal l a lang iaaii ri ’i- Malawasta, S. 11971 1 Vinblastine: colchicine’iike eff’cts

Chemokines, their receptors, and transplant outcome.

PubMed

Colvin, Bridget L; Thomson, Angus W

2002-07-27

Organ transplant rejection is mediated largely by circulating peripheral leukocytes induced to infiltrate the graft by various inflammatory stimuli. Of these, chemotactic cytokines called chemokines, expressed by inflamed graft tissues, as well as by early innate-responding leukocytes that infiltrate the graft, are responsible for the recruitment of alloreactive leukocytes. This report discusses the impact of these leukocyte-directing proteins on transplant outcome and novel therapeutic approaches for antirejection therapy based on targeting of chemokines and/or their receptors.

Effect of HSP27 on Human Breast Tumor Cell Growth and Motility.

DTIC Science & Technology

1997-09-01

the small heat shock protein, Hsp27 , on growth and motility characteristics of human mammary tumor cell lines. Since Hsp27 regulates actin...microfilament dynamics, we hypothesize that cells expressing high levels of Hsp27 will show increased motility and altered chemotactic properties, in addition to...significantly elevated levels of Hsp27 has proven to be daunting. Down regulation of Hsp27 levels in MCF7 cells using antisense technology has also

p53/PUMA expression in human pulmonary fibroblasts mediates cell activation and migration in silicosis.

PubMed

Wang, Wei; Liu, Haijun; Dai, Xiaoniu; Fang, Shencun; Wang, Xingang; Zhang, Yingming; Yao, Honghong; Zhang, Xilong; Chao, Jie

2015-11-18

Phagocytosis of SiO2 into the lung causes an inflammatory cascade that results in fibroblast proliferation and migration, followed by fibrosis. Clinical evidence has indicated that the activation of alveolar macrophages by SiO2 produces rapid and sustained inflammation characterized by the generation of monocyte chemotactic protein 1, which, in turn, induces fibrosis. However, the details of events downstream of monocyte chemotactic protein 1 activity in pulmonary fibroblasts remain unclear. Here, to elucidate the role of p53 in fibrosis induced by silica, both the upstream molecular mechanisms and the functional effects on cell proliferation and migration were investigated. Experiments using primary cultured adult human pulmonary fibroblasts led to the following results: 1) SiO2 treatment resulted in a rapid and sustained increase in p53 and PUMA protein levels; 2) the MAPK and PI3K pathways were involved in the SiO2-induced alteration of p53 and PUMA expression; and 3) RNA interference targeting p53 and PUMA prevented the SiO2-induced increases in fibroblast activation and migration. Our study elucidated a link between SiO2-induced p53/PUMA expression in fibroblasts and cell migration, thereby providing novel insight into the potential use of p53/PUMA in the development of novel therapeutic strategies for silicosis treatment.

Monocyte chemotactic protein-3: possible involvement in apical periodontitis chemotaxis.

PubMed

Dezerega, A; Osorio, C; Mardones, J; Mundi, V; Dutzan, N; Franco, M; Gamonal, J; Oyarzún, A; Overall, C M; Hernández, M

2010-10-01

To study the expression of monocyte chemotactic protein-3 (MCP-3, also known as chemokine CCL-7) in tissue from apical lesions (AL) and to associate MCP-3 expression with symptomatic or asymptomatic apical periodontitis. To determine the expression of MCP-3 in AL, biopsies obtained during tooth extraction procedures were fixed, subjected to routine processing and diagnosed as apical granuloma (AG) (n = 7) or radicular cyst (RC) (n = 5). As controls, apical periodontal ligament (PDL) specimens from healthy premolars extracted for orthodontics reasons were included (n = 7). All specimens were immunostained for MCP-3 and examined under a light microscope. In addition, homogenates from AL (n = 14) and healthy PDL samples (n = 7) were studied through immunowestern blot. Finally, periapical exudates samples were collected from root canals of teeth having diagnosis of symptomatic (n = 14) and asymptomatic apical periodontitis (n = 14) during routine endodontic treatments and analysed by immunowestern blot and densitometry.   MCP-3 was detected in AG and RC and localized mainly to inflammatory leucocytes, whereas no expression was observed in healthy PDLs. MCP-3 was also detected in periapical exudate, and its levels were significantly higher in symptomatic than in asymptomatic apical periodontitis. MCP-3 was expressed in AL and its levels associated with clinical symptoms. MCP-3 might play a role in disease pathogenesis, possibly by stimulating mononuclear chemotaxis. © 2010 International Endodontic Journal.

The chemokine MCP-1 (CCL2) in the host interaction with cancer: a foe or ally?

PubMed

Yoshimura, Teizo

2018-01-29

Macrophages are one of the most abundant leukocyte populations infiltrating tumor tissues and can exhibit both tumoricidal and tumor-promoting activities. In 1989, we reported the purification of monocyte chemoattractant protein-1 (MCP-1) from culture supernatants of mitogen-activated peripheral blood mononuclear cells and tumor cells. MCP-1 is a potent monocyte-attracting chemokine, identical to the previously described lymphocyte-derived chemotactic factor or tumor-derived chemotactic factor, and greatly contributes to the recruitment of blood monocytes into sites of inflammatory responses and tumors. Because in vitro-cultured tumor cells often produce significant amounts of MCP-1, tumor cells are considered to be the main source of MCP-1. However, various non-tumor cells in the tumor stroma also produce MCP-1 in response to stimuli. Studies performed in vitro and in vivo have provided evidence that MCP-1 production in tumors is a consequence of complex interactions between tumor cells and non-tumor cells and that both tumor cells and non-tumor cells contribute to the production of MCP-1. Although MCP-1 production was once considered to be a part of host defense against tumors, it is now believed to regulate the vicious cycle between tumor cells and macrophages that promotes the progression of tumors.Cellular and Molecular Immunology advance online publication, 29 January 2018; doi:10.1038/cmi.2017.135.

Macrophage activation by heparanase is mediated by TLR-2 and TLR-4 and associates with plaque progression.

PubMed

Blich, Miry; Golan, Amnon; Arvatz, Gil; Sebbag, Anat; Shafat, Itay; Sabo, Edmond; Cohen-Kaplan, Victoria; Petcherski, Sirouch; Avniel-Polak, Shani; Eitan, Amnon; Hammerman, Haim; Aronson, Doron; Axelman, Elena; Ilan, Neta; Nussbaum, Gabriel; Vlodavsky, Israel

2013-02-01

Factors and mechanisms that activate macrophages in atherosclerotic plaques are incompletely understood. We examined the capacity of heparanase to activate macrophages. Highly purified heparanase was added to mouse peritoneal macrophages and macrophage-like J774 cells, and the levels of tumor necrosis factor-α, matrix metalloproteinase-9, interlukin-1, and monocyte chemotactic protein-1 were evaluated by ELISA. Gene expression was determined by RT-PCR. Cells collected from Toll-like receptor-2 and Toll-like receptor-4 knockout mice were evaluated similarly. Heparanase levels in the plasma of patients with acute myocardial infarction, stable angina, and healthy subjects were determined by ELISA. Immunohistochemistry was applied to detect the expression of heparanase in control specimens and specimens of patients with stable angina or acute myocardial infarction. Addition or overexpression of heparanase variants resulted in marked increase in tumor necrosis factor-α, matrix metalloproteinase-9, interlukin-1, and monocyte chemotactic protein-1 levels. Mouse peritoneal macrophages harvested from Toll-like receptor-2 or Toll-like receptor-4 knockout mice were not activated by heparanase. Plasma heparanase level was higher in patients with acute myocardial infarction, compared with patients with stable angina and healthy subjects. Pathologic coronary specimens obtained from vulnerable plaques showed increased heparanase staining compared with specimens of stable plaque and controls. Heparanase activates macrophages, resulting in marked induction of cytokine expression associated with plaque progression toward vulnerability.

Cellular cAMP uptake as trigger for electrotaxis

NASA Astrophysics Data System (ADS)

Guido, Isabella; Bodenschatz, Eberhard

Cells have the ability to detect continuous current electric fields and respond to them with a directed migratory movement. Dictyostelium discoideum cells, a key model organism for the study of eukaryotic chemotaxis, orient and migrate toward the cathode under the influence of an electric field. The underlying sensing mechanism and whether it is shared by the chemotactic response pathway remains unknown. By investigating the migration in the electric field of cell strains unable to migrate chemotactically (Amib-null) and with defective cAMP relay (ACA-null) we show that the starvation-induced transcription of a set of genes involved in the early developmental stage is not necessary for electrotaxis. However, the analysis of electrotaxis of vegetative cells as well as shortly starved cells shows that cells need to be stimulated with cAMP in order for them to migrate electrotactically. Indeed 30 minutes stimulation with cAMP pulses is enough to let cells orienting with the electric field although during this time the expression of receptors and the beginning of the development has not happened yet. We believe that the reason for this observed phenomenon lies on the endocytosis of the external cAMP which triggers electrotaxis as long as endocytosis and exocytosis are not balanced. This work is part of the MaxSynBio Consortium which is jointly funded by the Federal Ministry of Education and Research of Germany and the Max Planck Society.

Quantification of chemotaxis during pediatric cardiac surgery by flow and laser scanning cytometry

NASA Astrophysics Data System (ADS)

Tarnok, Attila; Schmid, Joerg W.; Osmancik, Pavel; Lenz, Dominik; Pipek, Michal; Hambsch, Joerg; Gerstner, Andreas O.; Schneider, Peter

2002-05-01

Cardiac surgery with cardiopulmonary bypass (CPB) alters the leukocyte composition of the peripheral blood (PB). This response contributes to the sometimes adverse outcome with capillary leakage. Migration of activated cells to sites of inflammation, driven by chemokines is part of this response. In order to determine the chemotactic activity of patients serum during and after surgery we established an assay for PB leukocytes (PBL). PBL from healthy donors were isolated and 250,000 cells were placed into a migration chamber separated by a filter from a second lower chamber filled with patient serum. After incubation cells from top and bottom chamber were removed and stained with a cocktail of monoclonal antibodies for leukocyte subsets and analyzed on a flow cytometer (FCM). Cells at the bottom of the filter belong to the migrating compartment and were quantified by LSC after staining of nucleated cells. Increased chemotactic activity started at onset of anaesthesia followed by a phase of low activity immediately after surgery and a second phase of a high post-operative activity. The in vitro results correlated with results obtained by immunopenotyping of circulating PBL. Manipulation of the chemokine pattern might prove beneficial to prevent extravasation of cells leading to tissue damage. In chemotaxis assays with low amount of available serum the combined use of FCM and Laser Scanning LSC proved as an appropriate analytical tool.

Induction of the chemotactic S100 protein, CP-10, in monocyte/macrophages by lipopolysaccharide.

PubMed

Hu, S P; Harrison, C; Xu, K; Cornish, C J; Geczy, C L

1996-05-01

The murine S100 protein CP-10 is a potent chemotactic factor for murine and human myeloid cells in vivo and in vitro. This is the first report describing regulations of the CP-10 gene by a proinflammatory stimulus, lipopolysaccharide (LPS), in cells of the monocyte/macrophage lineage. Murine monocyte/macrophage-like WEHI 265 and RAW 264.7 cells preexposed to 5 to 50 ng/mL LPS expressed significant levels of CP-10 mRNA 4 hours, and maximal at 20 hours, after a secondary LPS challenge. This was accompanied by increasing levels of cell-associated and released CP-10 protein. In contrast, a single dose of LPS upregulated CP-10 mRNA in elicited peritoneal macrophages, whereas mRNA and protein levels decreased following LPS challenge. The state of macrophage differentiation may control responsiveness as LPS had no effect on CP-10 basal levels in bone marrow derived macrophages. LPS-induced CP-10 expression was controlled at the transcriptional level and nuclear run-on and protein synthesis inhibition assays indicated that LPS priming and challenge of RAW cells occurred via distinct pathways. MRP14, another S100 protein generally coordinately expressed with human MRP8, was not induced by LPS under the same conditions. We propose that CP-10 may play a key role in recruitment of leukocytes into tissues in response to gram-negative bacterial infection.

Branching instability in expanding bacterial colonies.

PubMed

Giverso, Chiara; Verani, Marco; Ciarletta, Pasquale

2015-03-06

Self-organization in developing living organisms relies on the capability of cells to duplicate and perform a collective motion inside the surrounding environment. Chemical and mechanical interactions coordinate such a cooperative behaviour, driving the dynamical evolution of the macroscopic system. In this work, we perform an analytical and computational analysis to study pattern formation during the spreading of an initially circular bacterial colony on a Petri dish. The continuous mathematical model addresses the growth and the chemotactic migration of the living monolayer, together with the diffusion and consumption of nutrients in the agar. The governing equations contain four dimensionless parameters, accounting for the interplay among the chemotactic response, the bacteria-substrate interaction and the experimental geometry. The spreading colony is found to be always linearly unstable to perturbations of the interface, whereas branching instability arises in finite-element numerical simulations. The typical length scales of such fingers, which align in the radial direction and later undergo further branching, are controlled by the size parameters of the problem, whereas the emergence of branching is favoured if the diffusion is dominant on the chemotaxis. The model is able to predict the experimental morphologies, confirming that compact (resp. branched) patterns arise for fast (resp. slow) expanding colonies. Such results, while providing new insights into pattern selection in bacterial colonies, may finally have important applications for designing controlled patterns. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Inhibition of chemiluminescence and chemotactic activity of phagocytes in vitro by the extracts of selected medicinal plants.

PubMed

Jantan, Ibrahim; Harun, Nurul Hikmah; Septama, Abdi Wira; Murad, Shahnaz; Mesaik, M A

2011-04-01

The methanol extracts of 20 selected medicinal plants were investigated for their effects on the respiratory burst of human whole blood, isolated human polymorphonuclear leukocytes (PMNs) and isolated mice macrophages using a luminol/lucigenin-based chemiluminescence assay. We also tested the effect of the extracts on chemotactic migration of PMNs using the Boyden chamber technique. The extracts of Curcuma domestica L., Phyllanthus amarus Schum & Thonn and C. xanthorrhiza Roxb. were the samples producing the strongest oxidative burst of PMNs with luminol-based chemiluminescence, with IC(50) values ranging from 0.5 to 0.7 μg/ml. For macrophage cells, the extracts which showed strong suppressive activity for luminol-based chemiluminescence were C. xanthorrhiza and Garcinia mangostana L. Among the extracts studied, C. mangga Valton & Vazsjip, Piper nigrum L. and Labisia pumila var. alata showed strong inhibitory activity on lucigenin-amplified oxidative burst of PMNs, with IC(50) values ranging from 0.9 to 1.5 μg/ml. The extracts of Zingiber officinale Rosc., Alpinia galangal (L.) Willd and Averrhoa bilimbi Linn showed strong inhibition on the chemotaxic migration of cells, with IC(50) values comparable to that of ibuprofen (1.5 μg/ml). The results suggest that some of these plants were able to modulate the innate immune response of phagocytes at different steps, emphasizing their potential as a source of new immunomodulatory agents.

Analysis of migration rate and chemotaxis of human adipose-derived mesenchymal stem cells in response to LPS and LTA in vitro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herzmann, Nicole; Salamon, Achim; Fiedler, Tomas

Mesenchymal stem cells (MSC) are able to stimulate the regeneration of injured tissue. Since bacterial infections are common complications in wound healing, bacterial pathogens and their components come into direct contact with MSC. The interaction with bacterial structures influences the proliferation, differentiation and migratory activity of the MSC, which might be of relevance during regeneration. Studies on MSC migration in response to bacterial components have shown different results depending on the cell type. Here, we analyzed the migration rate and chemotaxis of human adipose-derived MSC (adMSC) in response to the basic cell-wall components lipopolysaccharide (LPS) of Gram-negative bacteria and lipoteichoicmore » acid (LTA) of Gram-positive bacteria in vitro. To this end, we used transwell and scratch assays, as well as a specific chemotaxis assay combined with live-cell imaging. We found no significant influence of LPS or LTA on the migration rate of adMSC in transwell or scratch assays. Furthermore, in the µ-slide chemotaxis assay, the stimulation with LPS did not exert any chemotactic effect on adMSC. - Highlights: • LPS increased the release of IL-6 and IL-8 in adMSC significantly. • The migration rate of adMSC was not influenced by LPS or LTA. • LPS or LTA did not exert a chemotactic effect on adMSC.« less

Chemotaxis-mediated biodegradation of cyclic nitramine explosives RDX, HMX, and CL-20 by Clostridium sp. EDB2.

PubMed

Bhushan, Bharat; Halasz, Annamaria; Thiboutot, Sonia; Ampleman, Guy; Hawari, Jalal

2004-04-09

Cyclic nitramine explosives, RDX, HMX, and CL-20 are hydrophobic pollutants with very little aqueous solubility. In sediment and soil environments, they are often attached to solid surfaces and/or trapped in pores and distribute heterogeneously in aqueous environments. For efficient bioremediation of these explosives, the microorganism(s) must access them by chemotaxis ability. In the present study, we isolated an obligate anaerobic bacterium Clostridium sp. strain EDB2 from a marine sediment. Strain EDB2, motile with numerous peritrichous flagella, demonstrated chemotactic response towards RDX, HMX, CL-20, and NO(2)(-). The three explosives were biotransformed by strain EDB2 via N-denitration with concomitant release of NO(2)(-). Biotransformation rates of RDX, HMX, and CL-20 by the resting cells of strain EDB2 were 1.8+/-0.2, 1.1+/-0.1, and 2.6+/-0.2nmol h(-1)mgwet biomass(-1) (mean+/-SD; n=3), respectively. We found that commonly seen RDX metabolites such as TNX, methylenedinitramine, and 4-nitro-2,4-diazabutanal neither produced NO(2)(-) during reaction with strain EDB2 nor they elicited chemotaxis response in strain EDB2. The above data suggested that NO(2)(-) released from explosives during their biotransformation might have elicited chemotaxis response in the bacterium. Biodegradation and chemotactic ability of strain EDB2 renders it useful in accelerating the bioremediation of explosives under in situ conditions.

Inhibition of neutrophil migration by aggregated immunoglobulin attached to micropore membranes.

PubMed Central

Kemp, A S; Brown, S

1980-01-01

The effect of substrate-bound immunoglobulin on neutrophil migration was examined. Immunoglobulin aggregates bound to micropore membranes inhibited the neutrophil response to a chemotactic stimulus. This inhibition was reversed by the presence of aggregates in suspension suggesting competition between substrate-bound and free aggregates for neutrophil surface binding sites. The immobilization of neutrophils by substrate-bound aggregated immunoglobulin suggests a mechanism for the accumulation of neutrophils at sites of immune complex deposition and tissue-bound antibodies in vivo. PMID:7380477

ALTERATIONS OF MACROPHAGE FUNCTIONS BY MEDIATORS FROM LYMPHOCYTES

PubMed Central

Nathan, Carl F.; Karnovsky, Manfred L.; David, John R.

1971-01-01

Sensitized lymphocytes were incubated in vitro with the specific antigen Supernatants from these cultures were chromatographed on Sephadex G-100 columns. Supernatant fractions containing MIF, chemotactic factor, and lymphotoxin, but free of antigen and antibody, were incubated with normal peritoneal exudate macrophages. Macrophage adherence, phagocytosis, spreading, motility, and direct hexose monophosphate oxidation were enhanced, while protein synthesis was unaffected. Thus, antigen-stimulated lymphocytes secrete a factor or factors which enhance certain macrophage functions. Implications for models of cellular immunity and cellular hypersensitivity are discussed. PMID:5576335

Structural and Functional Analysis of HIV-1 Coreceptors: Roles of Charged Residues and Posttranslational Modifications on Coreceptor Activity

DTIC Science & Technology

2000-01-01

to sites of inflammation. They may have additional functions. For example analysis of CXCR4 knockout mice show that CXCR4, which is chemotactic for... mice had similar phenotypes (195). Homozygous knockout of CXCR4 or SDF-1 results in embyonic lethality. Though CCR5 appears to be dispensable, other...chemokine receptors have vital functions. CXCR5 knockout mice have B-cell homing defects (118), and CXCR2 knockout mice overproduce B-cells and

Identification and validation of vesicant therapeutic targets using a high, throughput siRNA screening approach

DTIC Science & Technology

2014-12-24

toxlet.2011.04.007 Rogers JV, Choi YW, Kiser RC et al (2004) Microarray analysis of gene expression in murine skin exposed to sulfur mustard. J Bio...Chemotactic factors released in culture by intact developing and healing skin lesions produced in rabbits by the irritant sulfur mustard. Inflam- mation 21(2...Project ID Number CBM.CUTOC.04.10. RC 00114. ABSTRACT See reprint. 15. SUBJECT TERMS sulfur mustard, cutaneous injury, siRNA, high-throughput screening

Cytokines in the host response to Candida vaginitis: Identifying a role for non-classical immune mediators, S100 alarmins

PubMed Central

Yano, Junko; Noverr, Mairi C.; Fidel, Paul L.

2011-01-01

Vulvovaginal candidiasis (VVC), caused by Candida albicans, affects a significant number of women during their reproductive years. More than two decades of research have been focused on the mechanisms associated with susceptibility or resistance to symptomatic infection. Adaptive immunity by Th1-type CD4+ T cells and downstream cytokine responses are considered the predominant host defense mechanisms against mucosal Candida infections. However, numerous clinical and animal studies have indicated no or limited protective role of cells and cytokines of the Th1 or Th2 lineage against vaginal infection. The role for Th17 is only now begun to be investigated in-depth for VVC with results already showing significant controversy. On the other hand, a clinical live-challenge study and an established animal model have shown that a symptomatic condition is intimately associated with the vaginal infiltration of polymorphonuclear leukocytes (PMNs) but with no effect on vaginal fungal burden. Subsequent studies identified S100A8 and S100A9 Alarmins as key chemotactic mediators of the acute PMN response. These chemotactic danger signals appear to be secreted by vaginal epithelial cells upon interaction and early adherence of Candida. Thus, instead of a putative immunodeficiency against Candida involving classical immune cells and cytokines of the adaptive response, the pathological inflammation in VVC is now considered a consequence of a non-productive innate response initiated by non-classical immune mediators. PMID:22182685

Identification of oligomer proanthocyanidins (F2) isolated from grape seeds as a formyl peptide receptor 1 partial agonist.

PubMed

Yang, Jingyu; Wang, Qing; Zhao, Ruijun; Sun, Baoshan; Wang, Lihui; Hou, Yue; Li, Xiaoqin; Wu, Chunfu

2013-04-01

Formyl peptide receptor 1 (FPR1) plays an important role in the rapid progression of glioblastoma and has been considered as a molecular target for the treatment. Previously, we have shown that oligomer proanthocyanidins (F2, degree of polymerization 2-15), isolated from grape seeds, inhibited FPR1-mediated chemotaxis of U-87 glioblastoma cells. In the present study, we investigated the capacity of F2 to interact with FPR1. The cross attenuation of chemotaxis revealed that F2 shared FPR1 with formyl-methionyl-leucyl-phenylalanine (fMLF), which is a prototype agonist of FPR1. F2 was chemotactic for U-87 cells, and the chemotactic response was abolished when FPR1 gene was silenced or FPR1 was competitively occupied. We further show that F2 specifically blocked the binding of fluorescent agonist to FPR1. Interestingly, F2 exhibited the characteristic of a partial agonist for FPR1, as shown by its capacity to activate FPR1-mediated PI3K-PKC-MAPK pathways. Meanwhile, F2 also attenuated fMLF-triggered MAPK activation, suggesting that F2 could antagonize the effect of an agonist. Furthermore, F2 abolished the invasion of U-87 cells induced by fMLF. Thus, we have identified F2 as a novel, partial agonist for FPR1, which may be useful for glioblastoma therapy. Copyright © 2013 Elsevier B.V. All rights reserved.

Systemic and myocardial inflammatory response in coronary artery bypass graft surgery with miniaturized extracorporeal circulation: differences with a standard circuit and off-pump technique in a randomized clinical trial.

PubMed

Formica, Francesco; Mariani, Silvia; Broccolo, Francesco; Caruso, Rosa; Corti, Fabrizio; D'Alessandro, Stefano; Amigoni, Pietro; Sangalli, Fabio; Paolini, Giovanni

2013-01-01

Inflammatory response and hemodilution are the main drawbacks of extracorporeal circulation. We hypothesize that the use of miniaturized extracorporeal circulation (MECC) might lower the systemic and myocardial inflammatory patterns compared with a standard system (SECC) and off-pump coronary artery bypass grafting (OPCABG). Sixty-one patients undergoing isolated coronary artery bypass graft were prospectively randomized to MECC (n = 19), SECC (n = 20), or OPCABG (n = 22). Blood samples were collected from radial artery and coronary sinus to analyze blood lactate, hemodilution, and markers for inflammation and endothelial activation such as tumor necrosis factor (TNF)-α, interleukin-6, monocyte chemotactic protein-1, and E-selectin. No differences were observed in early clinical outcome. Interleukin -6 levels increased in every group during and after cardiac surgery, whereas TNF-α values grew in the SECC group (p = 0.05). E-selectin systemic values decreased during and after operation (p = 0.001) in every group. Monocyte chemotactic protein-1 systemic and cardiac levels raised only in SECC group (p = 0.014). In conclusion, MECC is comparable to SECC and OPCABG in the clinical outcome of low-risk patients, and it might be extensively used with no additional intraoperative risk. The analysis of the inflammatory patterns of endothelial activation shows MECC as effective as OPCABG, suggesting further studies to clarify MECC recommendation in high-risk patients.

A bone substitute with high affinity for vitamin D-binding protein―relationship with niche of osteoclasts

PubMed Central

Ikeda, Tohru; Kasai, Michiyuki; Tatsukawa, Eri; Kamitakahara, Masanobu; Shibata, Yasuaki; Yokoi, Taishi; Nemoto, Takayuki K; Ioku, Koji

2014-01-01

The biological activity of osteoblasts and osteoclasts is regulated not only by hormones but also by local growth factors, which are expressed in neighbouring cells or included in bone matrix. Previously, we developed hydroxyapatite (HA) composed of rod-shaped particles using applied hydrothermal methods (HHA), and it revealed mild biodegradability and potent osteoclast homing activity. Here, we compared serum proteins adsorbed to HHA with those adsorbed to conventional HA composed of globular-shaped particles (CHA). The two ceramics adsorbed serum albumin and γ-globulin to similar extents, but affinity for γ-globulin was much greater than that to serum albumin. The chemotactic activity for macrophages of serum proteins adsorbed to HHA was significantly higher than that of serum proteins adsorbed to CHA. Quantitative proteomic analysis of adsorbed serum proteins revealed preferential binding of vitamin D-binding protein (DBP) and complements C3 and C4B with HHA. When implanted with the femur of 8-week-old rats, HHA contained significantly larger amount of DBP than CHA. The biological activity of DBP was analysed and it was found that the chemotactic activity for macrophages was weak. However, DBP-macrophage activating factor, which is generated by the digestion of sugar chains of DBP, stimulated osteoclastogenesis. These results confirm that the microstructure of hydroxyapatite largely affects the affinity for serum proteins, and suggest that DBP preferentially adsorbed to HA composed of rod-shaped particles influences its potent osteoclast homing activity and local bone metabolism. PMID:24286277

Theophylline therapy inhibits neutrophil and mononuclear cell chemotaxis from chronic asthmatic children.

PubMed Central

Condino-Neto, A; Vilela, M M; Cambiucci, E C; Ribeiro, J D; Guglielmi, A A; Magna, L A; De Nucci, G

1991-01-01

1. Theophylline is commonly used to relieve symptoms of chronic asthma. Since neutrophil and mononuclear cell activation are associated with late phase asthmatic reactions, effects of theophylline on these cells may be of importance. 2. In the present investigation we compared neutrophil and mononuclear cell chemotaxis from chronic asthmatic children during and after theophylline therapy. 3. Thirty patients were recruited for the study. Each patient received theophylline orally for 10 days. The theophylline dose was 20 mg kg-1 day-1 given in four divided doses. On the tenth day, blood was collected into heparinized (100 u ml-1) and siliconized tubes 2 h after the last theophylline dose for chemotactic assays, cAMP and theophylline plasma determinations. When clinical conditions allowed, theophylline was discontinued for 7 days and the chemotactic assays, cAMP and theophylline plasma concentrations repeated. Serum complement and IgE levels were also determined. 4. Theophylline therapy clearly inhibited both spontaneous and stimulated neutrophil and mononuclear cell chemotaxis. Twenty-seven patients had therapeutic plasma concentrations of theophylline (5-20 micrograms ml-1). Discontinuation of theophylline therapy caused a significant decrease in plasma cAMP levels (44 and 31 pmol ml-1 respectively during and after treatment, n = 30, P less than 0.001). 5. The inhibition of neutrophil and mononuclear cell migration by theophylline therapy in chronic asthmatic children may be beneficial for the control of the inflammatory response observed in these patients. PMID:1659436

Transverse bacterial migration induced by chemotaxis in a packed column with structured physical heterogeneity.

PubMed

Wang, Meng; Ford, Roseanne M

2009-08-01

The significance of chemotaxis in directing bacterial migration toward contaminants in natural porous media was investigated under groundwater flow conditions. A laboratory-scale column, with a coarse-grained sand core surrounded by a fine-grained annulus, was used to simulate natural aquifers with strata of different hydraulic conductivities. A chemoattractant source was placed along the central axis of the column to model contaminants trapped in the heterogeneous subsurface. Chemotactic bacterial strains, Escherichia coli HCB1 and Pseudomonas putida F1, introduced into the column by a pulse injection, were found to alter their transport behaviors under the influence of the attractant chemical emanating from the central source. For E. coil HCB1, approximately 18% more of the total population relative to the control without attractant exited the column from the coarse sand layer due to the chemotactic effects of alpha-methylaspartate under an average fluid velocity of 5.1 m/d. Although P. putida F1 demonstrated no observable changes in migration pathways with the model contaminant acetate under the same flow rate, when the flow rate was reduced to 1.9 m/d, approximately 6-10% of the population relative to the control migrated from the fine sand layer toward attractant into the coarse sand layer. Microbial transport properties were further quantified by a mathematical model to examine the significance of bacterial motility and chemotaxis under different hydrodynamic conditions, which suggested important considerations for strain selection and practical operation of bioremediation schemes.

Evidence for differential activation of arachidonic acid metabolism in formylpeptide- and macrophage-activation-factor-stimulated guinea-pig macrophages.

PubMed Central

Homma, Y; Hashimoto, T; Nagai, Y; Takenawa, T

1985-01-01

Alterations of phospholipid and arachidonic acid metabolism were studied by treatment of guinea-pig peritoneal-exudate macrophages with chemotactic peptide, formylmethionyl-leucylphenylalanine (fMet-Leu-Phe) and macrophage activation factor (MAF). The chemotactic peptide caused a rapid rearrangement in inositol phospholipids, including a breakdown of polyphosphoinositides within 30s, followed by a resultant formation of phosphatidylinositol (PI), diacylglycerol, phosphatidic acid and non-esterified arachidonic acid within 5 min. In addition to these sequential alterations, arachidonic acid was released mainly from PI. On the other hand, MAF induced a slow liberation of arachidonic acid, mainly from phosphatidylethanolamine (PE) and phosphatidylcholine (PC) by phospholipase A2 after the incubation period of 30 min, but not any rapid changes in phospholipids. Treatment of macrophages for 15 min with fMet-Leu-Phe produced the leukotrienes (LTs) B4, C4 and D4, prostaglandins (PG) E2 and F2 alpha and thromboxane (TX) B2. In contrast, MAF could not stimulate the production of arachidonic acid metabolites during the incubation period of 15 min, but could enhance that of PGE2, PGF2 alpha, TXB2 and hydroxyeicosatetraenoic acids at 6 h. However, the stimulated formation of LTs was not detected at any time. These results indicate that the effects of fMet-Leu-Phe on both phospholipid and arachidonic acid metabolism are very different from those mediated by MAF. PMID:3931627

Monocyte chemotactic protein-1 deficiency attenuates and high-fat diet exacerbates bone loss in mice with Lewis lung carcinoma.

PubMed

Yan, Lin; Nielsen, Forrest H; Sundaram, Sneha; Cao, Jay

2017-04-04

Bone loss occurs in obesity and cancer-associated complications including wasting. This study determined whether a high-fat diet and a deficiency in monocyte chemotactic protein-1 (MCP-1) altered bone structural defects in male C57BL/6 mice with Lewis lung carcinoma (LLC) metastases in lungs. Compared to non-tumor-bearing mice, LLC reduced bone volume fraction, connectivity density, trabecular number, trabecular thickness and bone mineral density and increased trabecular separation in femurs. Similar changes occurred in vertebrae. The high-fat diet compared to the AIN93G diet exacerbated LLC-induced detrimental structural changes; the exacerbation was greater in femurs than in vertebrae. Mice deficient in MCP-1 compared to wild-type mice exhibited increases in bone volume fraction, connectivity density, trabecular number and decreases in trabecular separation in both femurs and vertebrae, and increases in trabecular thickness and bone mineral density and a decrease in structure model index in vertebrae. Lewis lung carcinoma significantly decreased osteocalcin but increased tartrate-resistant acid phosphatase 5b (TRAP 5b) in plasma. In LLC-bearing mice, the high-fat diet increased and MCP-1 deficiency decreased plasma TRAP 5b; neither the high-fat diet nor MCP-1 deficiency resulted in significant changes in plasma concentration of osteocalcin. In conclusion, pulmonary metastasis of LLC is accompanied by detrimental bone structural changes; MCP-1 deficiency attenuates and high-fat diet exacerbates the metastasis-associated bone wasting.

Rheotaxis guides mammalian sperm

PubMed Central

Miki, Kiyoshi; Clapham, David E

2013-01-01

Background In sea urchins, spermatozoan motility is altered by chemotactic peptides, giving rise to the assumption that mammalian eggs also emit chemotactic agents that guide spermatozoa through the female reproductive tract to the mature oocyte. Mammalian spermatozoa indeed undergo complex adaptations within the female (the process of capacitation) that are initiated by agents ranging from pH to progesterone, but these factors are not necessarily taxic. Currently, chemotaxis, thermotaxis, and rheotaxis have not been definitively established in mammals. Results Here, we show that positive rheotaxis, the ability of organisms to orient and swim against the flow of surrounding fluid, is a major taxic factor for mouse and human sperm. This flow is generated within 4 hours of sexual stimulation and coitus in female mice; prolactin-triggered oviductal fluid secretion clears the oviduct of debris, lowers viscosity, and generates the stream that guides sperm migration in the oviduct. Rheotaxic movement is demonstrated in capacitated and uncapacitated spermatozoa in low and high viscosity medium. Finally, we show that a unique sperm motion we quantify using the sperm head's rolling rate reflects sperm rotation that generates essential force for positioning the sperm in the stream. Rotation requires CatSper channels, presumably by enabling Ca2+ influx. Conclusions We propose that rheotaxis is a major determinant of sperm guidance over long distances in the mammalian female reproductive tract. Coitus induces fluid flow to guide sperm in the oviduct. Sperm rheotaxis requires rotational motion during CatSper channel-dependent hyperactivated motility. PMID:23453951

Human Rhinovirus Infection of Epithelial Cells Modulates Airway Smooth Muscle Migration.

PubMed

Shariff, Sami; Shelfoon, Christopher; Holden, Neil S; Traves, Suzanne L; Wiehler, Shahina; Kooi, Cora; Proud, David; Leigh, Richard

2017-06-01

Airway remodeling, a characteristic feature of asthma, begins in early life. Recurrent human rhinovirus (HRV) infections are a potential inciting stimulus for remodeling. One component of airway remodeling is an increase in airway smooth muscle cell (ASMC) mass with a greater proximity of the ASMCs to the airway epithelium. We asked whether human bronchial epithelial cells infected with HRV produced mediators that are chemotactic for ASMCs. ASMC migration was investigated using the modified Boyden Chamber and the xCELLigence Real-Time Cell Analyzer (ACEA Biosciences Inc., San Diego, CA). Multiplex bead analysis was used to measure HRV-induced epithelial chemokine release. The chemotactic effects of CCL5, CXCL8, and CXCL10 were also examined. Supernatants from HRV-infected epithelial cells caused ASMC chemotaxis. Pretreatment of ASMCs with pertussis toxin abrogated chemotaxis, as did treatment with formoterol, forskolin, or 8-bromo-cAMP. CCL5, CXCL8, and CXCL10 were the most up-regulated chemokines produced by HRV-infected airway epithelial cells. When recombinant CCL5, CXCL8, and CXCL10 were used at levels found in epithelial supernatants, they induced ASMC chemotaxis similar to that seen with epithelial cell supernatants. When examined individually, CCL5 was the most effective chemokine in causing ASMC migration, and treatment of supernatant from HRV-infected epithelial cells with anti-CCL5 antibodies significantly attenuated ASMC migration. These findings suggest that HRV-induced CCL5 can induce ASMC chemotaxis and thus may contribute to the pathogenesis of airway remodeling in patients with asthma.

The spectrum of resistance in SR/CR mice: the critical role of chemoattraction in the cancer/leukocyte interaction.

PubMed

Riedlinger, Gregory; Adams, Jonathan; Stehle, John R; Blanks, Michael J; Sanders, Anne M; Hicks, Amy M; Willingham, Mark C; Cui, Zheng

2010-05-03

Spontaneous regression/complete resistance (SR/CR) mice are a unique colony of mice that possess an inheritable, natural cancer resistance mediated primarily by innate cellular immunity. This resistance is effective against sarcoma 180 (S180) at exceptionally high doses and these mice remain healthy. In this study, we challenged SR/CR mice with additional lethal transplantable mouse cancer cell lines to determine their resistance spectrum. The ability of these transplantable cancer cell lines to induce leukocyte infiltration was quantified and the percentage of different populations of responding immune cells was determined using flow cytometry. In comparison to wild type (WT) mice, SR/CR mice showed significantly higher resistance to all cancer cell lines tested. However, SR/CR mice were more sensitive to MethA sarcoma (MethA), B16 melanoma (B16), LL/2 lung carcinoma (LL/2) and J774 lymphoma (J774) than to sarcoma 180 (S180) and EL-4 lymphoma (EL-4). Further mechanistic studies revealed that this lower resistance to MethA and LL/2 was due to the inability of these cancer cells to attract SR/CR leukocytes, leading to tumor cell escape from resistance mechanism. This escape mechanism was overcome by co-injection with S180, which could attract SR/CR leukocytes allowing the mice to resist higher doses of MethA and LL/2. S180-induced cell-free ascites fluid (CFAF) co-injection recapitulated the results obtained with live S180 cells, suggesting that this chemoattraction by cancer cells is mediated by diffusible molecules. We also tested for the first time whether SR/CR mice were able to resist additional cancer cell lines prior to S180 exposure. We found that SR/CR mice had an innate resistance against EL-4 and J774. Our results suggest that the cancer resistance in SR/CR mice is based on at least two separate processes: leukocyte migration/infiltration to the site of cancer cells and recognition of common surface properties on cancer cells. The infiltration of SR/CR leukocytes was based on both the innate ability of leukocytes to respond to chemotactic signals produced by cancer cells and on whether cancer cells produced these chemotactic signals. We found that some cancer cells could escape from SR/CR resistance because they did not induce infiltration of SR/CR leukocytes. However, if infiltration of leukocytes was induced by co-injection with chemotactic factors, these same cancer cells could be effectively recognized and killed by SR/CR leukocytes.

Pathogenesis and Treatment of Skin Lesions Caused by Sulfur Mustard: Inflammatory Mediators and Modulators Released from Organ-Cultured Inflammatory Lesions Produced in Vivo in Rabbit Skin by Sulfur Mustard

DTIC Science & Technology

1987-02-20

fibroblast growth factors . Soon, we shall be able to use such products to stimulate specific cell types. Knowledge of the mediators produced by each cell type...source of some of these enzymes. 7. Finally, we have begun an extensive investigation on chemotactic fac- tors present in SM lesions. Factors ...gamma-interferon, Interleukin 1, and epi- dermal and fibroblast growth factors . Soon we shall be able to use such products to stimulate specific

Mechanism underlying the diverse collective behavior in the swarm oscillator model

NASA Astrophysics Data System (ADS)

Iwasa, Masatomo; Tanaka, Dan

2017-09-01

The swarm oscillator model describes the long-time behavior of interacting chemotactic particles, and it shows numerous types of macroscopic patterns. However, the reason why so many kinds of patterns emerge is not clear. In this study, we elucidate the mechanism underlying the diversity of the pattens by analyzing the model for two particles. Focusing on the behavior when the two particles are spatially close, we find that the dynamics is classified into eight types, which explain most of the observed 13 types of patterns.

Verification of epigenetic inheritance in a unicellular model system: multigenerational effects of hormonal imprinting.

PubMed

Kőhidai, László; Lajkó, Eszter; Pállinger, Eva; Csaba, György

2012-10-01

The unicellular Tetrahymena has receptors for hormones of higher vertebrates, produces these hormones, and their signal pathways are similar. The first encounter with a hormone in higher dose provokes the phenomenon of hormonal imprinting, by which the reaction of the cell is quantitatively modified. This modification is transmitted to the progeny generations. The duration of the single imprinter effect of two representative signal molecules, insulin and 5-HT (5-hydroxytryptamine), in two concentrations (10(-6) and 10(-15) M) were studied. The effects of imprinting were followed in 5 physiological indices: (i) insulin binding, (ii) 5-HT synthesis, (iii) swimming behaviour, (iv) cell growth and (v) chemotaxis in progeny generations 500 and 1000. The result of each index was different from the non-imprinted control functions, growth rate, swimming behaviour and chemotactic activity to insulin being enhanced, while others, e.g. synthesis and chemotactic responsiveness of 5-HT and the binding of insulin were reduced. This means that a function-specific heritable epigenetic change during imprinting occurs, and generally a single encounter with a femtomolar hormone concentration is enough for provoking durable and heritable imprinting in Tetrahymena. The experiments demonstrate the possibility of epigenetic effects at a unicellular level and call attention to the possibility that the character of unicellular organisms has changed through to the present day due to an enormous amount of non-physiological imprinter substances in their environment. The results - together with results obtained earlier in mammals - point to the validity of epigenetic imprinting effects throughout the animal world.

The ectoenzyme-side of matrix metalloproteinases (MMPs) makes inflammation by serum amyloid A (SAA) and chemokines go round.

PubMed

De Buck, Mieke; Gouwy, Mieke; Struyf, Sofie; Opdenakker, Ghislain; Van Damme, Jo

2018-06-02

During an inflammatory response, a large number of distinct mediators appears in the affected tissues or in the blood circulation. These include acute phase proteins such as serum amyloid A (SAA), cytokines and chemokines and proteolytic enzymes. Although these molecules are generated within a cascade sequence in specific body compartments allowing for independent action, their co-appearance in space and time during acute or chronic inflammation points toward important mutual interactions. Pathogen-associated molecular patterns lead to fast induction of the pro-inflammatory endogenous pyrogens, which are evoking the acute phase response. Interleukin-1, tumor necrosis factor-α and interferons simultaneously trigger different cell types, including leukocytes, endothelial cells and fibroblasts for tissue-specific or systemic production of chemokines and matrix metalloproteinases (MMPs). In addition, SAA induces chemokines and both stimulate secretion of MMPs from multiple cell types. As a consequence, these mediators may cooperate to enhance the inflammatory response. Indeed, SAA synergizes with chemokines to increase chemoattraction of monocytes and granulocytes. On the other hand, MMPs post-translationally modify chemokines and SAA to reduce their activity. Indeed, MMPs internally cleave SAA with loss of its cytokine-inducing and direct chemotactic potential whilst retaining its capacity to synergize with chemokines in leukocyte migration. Finally, MMPs truncate chemokines at their NH 2 - or COOH-terminal end, resulting in reduced or enhanced chemotactic activity. Therefore, the complex interactions between chemokines, SAA and MMPs either maintain or dampen the inflammatory response. Copyright © 2018. Published by Elsevier B.V.

The calcium-activated potassium channel KCa3.1 plays a central role in the chemotactic response of mammalian neutrophils

PubMed Central

Henríquez, C.; Riquelme, T. T.; Vera, D.; Julio-Kalajzić, F.; Ehrenfeld, P.; Melvin, J. E.; Figueroa, C. D.; Sarmiento, J.; Flores, C. A.

2017-01-01

Aim Neutrophils are the first cells to arrive at sites of injury. Nevertheless, many inflammatory diseases are characterized by an uncontrolled infiltration and action of these cells. Cell migration depends on volume changes that are governed by ion channel activity, but potassium channels in neutrophil have not been clearly identified. We aim to test whether KCa3.1 participates in neutrophil migration and other relevant functions of the cell. Methods Cytometer and confocal measurements to determine changes in cell volume were used. Cells isolated from human, mouse and horse were tested for KCa3.1-dependent chemotaxis. Chemokinetics, calcium handling and release of reactive oxygen species were measured to determine the role of KCa3.1 in those processes. A mouse model was used to test for neutrophil recruitment after acute lung injury in vivo. Results We show for the first time that KCa3.1 is expressed in mammalian neutrophils. When the channel is inhibited by a pharmacological blocker or by genetic silencing, it profoundly affects cell volume regulation, and chemotactic and chemokinetic properties of the cells. We also demonstrated that pharmacological inhibition of KCa3.1 did not affect calcium entry or reactive oxygen species production in neutrophils. Using a mouse model of acute lung injury, we observed that Kca3.1−/− mice are significantly less effective at recruiting neutrophils into the site of inflammation. Conclusions These results demonstrate that KCa3.1 channels are key actors in the migration capacity of neutrophils, and its inhibition did not affect other relevant cellular functions. PMID:26138196

The deadly swimming of Cercariae: an unusual Stokesian swimmer

NASA Astrophysics Data System (ADS)

Prakash, Manu; Krishnamurthy, Deepak

2014-11-01

Schistosomiasis, also known as Bilharzia, is a Neglected Tropical Disease (NTD) caused by a parasitic Trematode blood fluke worm. In terms of socio-economic and public health impact, Schistosomiasis is second only to Malaria as the most devastating parasitic disease in tropical countries; with roughly 200 million people infected at any time world-wide and up to 200,000 deaths every year. The infectious form of the parasite, known as Cercariae, emerge from snails into freshwater and infect humans by directly burrowing into the skin. Thus, anyone in contact with infected waters is at risk, which mostly includes children. By establishing a safe experimental means of studying the Cercariae in our lab, we report here their unusual swimming dynamics which include both head-first and tail-first swimming modes. These swimming modes are crucial for the chemotactic activity of Cercariae which allows them to seek out and burrow into human skin. By experimental and analytical means, we demonstrate that Cercariae break symmetry and achieve locomotion at small Reynolds number differently when compared to well-known methods involving traveling waves in the flagellum or chiral beating. Although they utilize the well-known drag anisotropy of a slender body in Stokes flow, the geometry and kinematics of their propulsion mechanism is novel. Based on these results, we propose a new kind of simple Stokesian swimmer (T-joint swimmer) in an attempt to explain the evolutionary advantages of this novel swimming mechanism. Using the above physical insights from a biological and global-health standpoint, we explore ways to hinder the chemotactic capabilities of this parasite.

Mast cells and their mediators in cutaneous wound healing--active participants or innocent bystanders?

PubMed

Artuc, M; Hermes, B; Steckelings, U M; Grützkau, A; Henz, B M

1999-02-01

Mast cells are traditionally viewed as effector cells of immediate type hypersensitivity reactions. There is, however, a growing body of evidence that the cells might play an important role in the maintenance of tissue homeostasis and repair. We here present our own data and those from the literature elucidating the possible role of mast cells during wound healing. Studies on the fate of mast cells in scars of varying ages suggest that these cells degranulate during wounding, with a marked decrease of chymase-positive cells, although the total number of cells does not decrease, based on SCF-receptor staining. Mast cells contain a plethora of preformed mediators like heparin, histamine, tryptase, chymase, VEGF and TNF-alpha which, on release during the initial stages of wound healing, affect bleeding and subsequent coagulation and acute inflammation. Various additional vasoactive and chemotactic, rapidly generated mediators (C3a, C5a, LTB4, LTC4, PAF) will contribute to these processes, whereas mast cell-derived proinflammatory and growth promoting peptide mediators (VEGF, FGF-2, PDGF, TGF-beta, NGF, IL-4, IL-8) contribute to neoangiogenesis, fibrinogenesis or re-epithelization during the repair process. The increasing number of tryptase-positive mast cells in older scars suggest that these cells continue to be exposed to specific chemotactic, growth- and differentiation-promoting factors throughout the process of tissue remodelling. All these data indicate that mast cells contribute in a major way to wound healing. their role as potential initiators of or as contributors to this process, compared to other cell types, will however have to be further elucidated.

Actin cytoskeleton of chemotactic amoebae operates close to the onset of oscillations

PubMed Central

Westendorf, Christian; Negrete, Jose; Bae, Albert J.; Sandmann, Rabea; Bodenschatz, Eberhard; Beta, Carsten

2013-01-01

The rapid reorganization of the actin cytoskeleton in response to external stimuli is an essential property of many motile eukaryotic cells. Here, we report evidence that the actin machinery of chemotactic Dictyostelium cells operates close to an oscillatory instability. When averaging the actin response of many cells to a short pulse of the chemoattractant cAMP, we observed a transient accumulation of cortical actin reminiscent of a damped oscillation. At the single-cell level, however, the response dynamics ranged from short, strongly damped responses to slowly decaying, weakly damped oscillations. Furthermore, in a small subpopulation, we observed self-sustained oscillations in the cortical F-actin concentration. To substantiate that an oscillatory mechanism governs the actin dynamics in these cells, we systematically exposed a large number of cells to periodic pulse trains of different frequencies. Our results indicate a resonance peak at a stimulation period of around 20 s. We propose a delayed feedback model that explains our experimental findings based on a time-delay in the regulatory network of the actin system. To test the model, we performed stimulation experiments with cells that express GFP-tagged fusion proteins of Coronin and actin-interacting protein 1, as well as knockout mutants that lack Coronin and actin-interacting protein 1. These actin-binding proteins enhance the disassembly of actin filaments and thus allow us to estimate the delay time in the regulatory feedback loop. Based on this independent estimate, our model predicts an intrinsic period of 20 s, which agrees with the resonance observed in our periodic stimulation experiments. PMID:23431176

Neuroendocrine immunomodulation network dysfunction in SAMP8 mice and PrP-hAβPPswe/PS1ΔE9 mice: potential mechanism underlying cognitive impairment

PubMed Central

Wang, Jian-hui; Cheng, Xiao-rui; Zhang, Xiao-rui; Wang, Tong-xing; Xu, Wen-jian; Li, Fei; Liu, Feng; Cheng, Jun-ping; Bo, Xiao-chen; Wang, Sheng-qi; Zhou, Wen-xia; Zhang, Yong-xiang

2016-01-01

Senescence-accelerated mouse prone 8 strain (SAMP8) and PrP-hAβPPswe/PS1ΔE9 (APP/PS1) mice are classic animal models of sporadic Alzheimer's disease and familial AD respectively. Our study showed that object recognition memory, spatial learning and memory, active and passive avoidance were deteriorated and neuroendocrine immunomodulation (NIM) network was imbalance in SAMP8 and APP/PS1 mice. SAMP8 and APP/PS1 mice had their own specific phenotype of cognition, neuroendocrine, immune and NIM molecular network. The endocrine hormone corticosterone, luteinizing hormone and follicle-stimulating hormone, chemotactic factor monocyte chemotactic protein-1, macrophage inflammatory protein-1β, regulated upon activation normal T cell expressed and secreted factor and eotaxin, pro-inflammatory factor interleukin-23, and the Th1 cell acting as cell immunity accounted for cognitive deficiencies in SAMP8 mice, while adrenocorticotropic hormone and gonadotropin-releasing hormone, colony stimulating factor granulocyte colony stimulating factor, and Th2 cell acting as humoral immunity in APP/PS1 mice. On the pathway level, chemokine signaling and T cell receptor signaling pathway played the key role in cognition impairments of two models, while cytokine-cytokine receptor interaction and natural killer cell mediated cytotoxicity were more important in cognitive deterioration of SAMP8 mice than APP/PS1 mice. This mechanisms of NIM network underlying cognitive impairment is significant for further understanding the pathogenesis of AD and can provide useful information for development of AD therapeutic drug. PMID:27049828

Insufficient OPC migration into demyelinated lesions is a cause of poor remyelination in MS and mouse models.

PubMed

Boyd, Amanda; Zhang, Hui; Williams, Anna

2013-06-01

Failure of remyelination of multiple sclerosis (MS) lesions contributes to neurodegeneration that correlates with chronic disability in patients. Currently, there are no available treatments to reduce neurodegeneration, but one therapeutic approach to fill this unmet need is to promote remyelination. As many demyelinated MS lesions contain plentiful oligodendrocyte precursor cells (OPCs), but no mature myelinating oligodendrocytes, research has previously concentrated on promoting OPC maturation. However, some MS lesions contain few OPCs, and therefore, remyelination failure may also be secondary to OPC recruitment failure. Here, in a series of MS samples, we determined how many lesions contained few OPCs, and correlated this to pathological subtype and expression of the chemotactic molecules Semaphorin (Sema) 3A and 3F. 37 % of MS lesions contained low numbers of OPCs, and these were mostly chronic active lesions, in which cells expressed Sema3A (chemorepellent). To test the hypothesis that differential Sema3 expression in demyelinated lesions alters OPC recruitment and the efficiency of subsequent remyelination, we used a focal myelinotoxic mouse model of demyelination. Adding recombinant (r)Sema3A (chemorepellent) to demyelinated lesions reduced OPC recruitment and remyelination, whereas the addition of rSema3F (chemoattractant), or use of transgenic mice with reduced Sema3A expression increased OPC recruitment and remyelination. We conclude that some MS lesions fail to remyelinate secondary to reduced OPC recruitment, and that chemotactic molecules are involved in the mechanism, providing a new group of drug targets to improve remyelination, with a specific target in the Sema3A receptor neuropilin-1.

Leukocyte Chemotactic Factor 2 (LECT2)-Associated Renal Amyloidosis: A Case Series

PubMed Central

Murphy, Charles L.; Wang, Shuching; Kestler, Daniel; Larsen, Christopher; Benson, Don; Weiss, Deborah T.; Solomon, Alan

2010-01-01

Background Renal amyloidosis is characterized by the pathologic deposition within glomeruli and/or interstitium of congophilic fibrils most often comprised of either immunoglobulin light chains or serum amyloid A-related protein and, less commonly, mutated forms of apolipoproteins AI or AII, lysozyme, fibrinogen, gelsolin, or transthyretin. Study Design Case Series. Setting and Participants Ten patients with renal amyloidosis who had an amyloidogenic protein that was not identified by routine immunohistochemistry. Outcomes Clinical, pathologic, biochemical, and genetic characteristics. Measurements Tandem mass spectrometry was used to analyze fibrils extracted from sections of formalin-fixed, paraffin-embedded amyloid-containing kidney biopsy blocks. Results The chemical analyses revealed peptides corresponding to the carboxy-terminal portion of the leukocyte chemotactic factor 2 (LECT2) molecule; further, the deposits were immunostained by an anti-human LECT2 monoclonal antibody. Plasma specimens were available from 2 individuals where the concentration of LECT2 in these samples was within normal limits. Additionally, in 4 of the cases analyzed at the molecular level, isolation of genomic DNA and PCR amplification of LECT2-encoding exons evidenced no mutations; however, all were homozygous for the G allele encoding valine at position 40 in the mature protein, a finding that was confirmed by restriction enzyme analysis of the polymorphic site. Limitations Causality is not addressed. Conclusions Based on our studies, we posit that LECT2-associated renal amyloidosis represents a unique and perhaps not uncommon disease, especially among Mexican Americans, the pathogenesis, extent, and prognosis of which remain to be determined. PMID:20951486

Mast cell migration to Th2 stimulated airway smooth muscle from asthmatics

PubMed Central

Sutcliffe, A; Kaur, D; Page, S; Woodman, L; Armour, C L; Baraket, M; Bradding, P; Hughes, J M; Brightling, C E

2006-01-01

Background Mast cell microlocalisation within the airway smooth muscle (ASM) bundle is an important determinant of the asthmatic phenotype. We hypothesised that mast cells migrate towards ASM in response to ASM derived chemokines. Methods Primary ASM cultures from subjects with and without asthma were stimulated with interleukin (IL)‐1β, IL‐4, and IL‐13 alone and in combination. Mast cell chemotaxis towards these ASM supernatants was investigated, and the chemotaxins mediating migration by using specific blocking antibodies for stem cell factor (SCF) and the chemokine receptors CCR3, CXCR1, 3 and 4 as well as the Gi inhibitor pertussis toxin and the tyrosine kinase inhibitor genistein were defined. The concentrations of CCL11, CXCL8, CXCL10, TGF‐β, and SCF in the supernatants were measured and the effect of non‐asthmatic ASM supernatants on the mast cell chemotactic activity of asthmatic ASM was examined. Results Human lung mast cells and HMC‐1 cells migrated towards Th2 stimulated ASM from asthmatics but not non‐asthmatics. Mast cell migration was mediated through the combined activation of CCR3 and CXCR1. CCL11 and CXCL8 expression by ASM increased markedly after stimulation, but was similar in those with and without asthma. ASM supernatants from non‐asthmatics inhibited mast cell migration towards the asthmatic ASM supernatant. Conclusion Th2 stimulated ASM from asthmatics is chemotactic for mast cells. Non‐asthmatic ASM releases a mediator or mediators that inhibit mast cell migration towards stimulated asthmatic ASM. Specifically targeting mast cell migration into the ASM bundle may provide a novel treatment for asthma. PMID:16601090

Chemotactic Signaling by Single-Chain Chemoreceptors

PubMed Central

Mowery, Patricia; Ames, Peter; Reiser, Rebecca H.; Parkinson, John S.

2015-01-01

Bacterial chemoreceptors of the methyl-accepting chemotaxis protein (MCP) family operate in commingled clusters that enable cells to detect and track environmental chemical gradients with high sensitivity and precision. MCP homodimers of different detection specificities form mixed trimers of dimers that facilitate inter-receptor communication in core signaling complexes, which in turn assemble into a large signaling network. The two subunits of each homodimeric receptor molecule occupy different locations in the core complexes. One subunit participates in trimer-stabilizing interactions at the trimer axis, the other lies on the periphery of the trimer, where it can interact with two cytoplasmic proteins: CheA, a signaling autokinase, and CheW, which couples CheA activity to receptor control. As a possible tool for independently manipulating receptor subunits in these two structural environments, we constructed and characterized fused genes for the E. coli serine chemoreceptor Tsr that encoded single-chain receptor molecules in which the C-terminus of the first Tsr subunit was covalently connected to the N-terminus of the second with a polypeptide linker. We showed with soft agar assays and with a FRET-based in vivo CheA kinase assay that single-chain Tsr~Tsr molecules could promote serine sensing and chemotaxis responses. The length of the connection between the joined subunits was critical. Linkers nine residues or shorter locked the receptor in a kinase-on state, most likely by distorting the native structure of the receptor HAMP domain. Linkers 22 or more residues in length permitted near-normal Tsr function. Few single-chain molecules were found as monomer-sized proteolytic fragments in cells, indicating that covalently joined receptor subunits were responsible for mediating the signaling responses we observed. However, cysteine-directed crosslinking, spoiling by dominant-negative Tsr subunits, and rearrangement of ligand-binding site lesions revealed subunit swapping interactions that will need to be taken into account in experimental applications of single-chain chemoreceptors. PMID:26709829

An Ultrasensitive Bacterial Motor Revealed by Monitoring Signaling Proteins in Single Cells

NASA Astrophysics Data System (ADS)

Cluzel, Philippe; Surette, Michael; Leibler, Stanislas

2000-03-01

Understanding biology at the single-cell level requires simultaneous measurements of biochemical parameters and behavioral characteristics in individual cells. Here, the output of individual flagellar motors in Escherichia coli was measured as a function of the intracellular concentration of the chemotactic signaling protein. The concentration of this molecule, fused to green fluorescent protein, was monitored with fluorescence correlation spectroscopy. Motors from different bacteria exhibited an identical steep input-output relation, suggesting that they actively contribute to signal amplification in chemotaxis. This experimental approach can be extended to quantitative in vivo studies of other biochemical networks.

Experimental Study on the Efficacy of Site-Specific PEGylated Human Serum Albumins in Resuscitation From Hemorrhagic Shock.

PubMed

Song, Xinlei; Zhang, Shu; Cheng, Yanna; Zhao, Ting; Lian, Qianqian; Lu, Lu; Wang, Fengshan

2016-11-01

To evaluate the resuscitative efficacy and the effect on reperfusion injury of two site-specific PEGylated human serum albumins modified with linear or branched PEG20kDa, compared with saline, 8% human serum albumin and 25% human serum albumin, in a hemorrhagic shock model. Laboratory. Male Wistar rats. Prospective study. Rats were bled to hemorrhagic hypovolemic shock and resuscitated with different resuscitation fluids. The mean arterial pressure and blood gas variables were measured. Hemorheology analysis was performed to evaluate the influence of resuscitation on RBCs and blood viscosity. The microvascular state was indirectly characterized in terms of monocyte chemotactic protein-1 and endothelial nitric oxide synthase that related to shear stress and vasodilation, respectively. The levels of inflammation-related factors and apoptosis-related proteins were used to evaluate the reperfusion injury in lungs. The results showed that PEGylated human serum albumin could improve the level of mean arterial pressure and blood gas variables more effectively at the end of resuscitation. poly(ethylene glycol) modification was able to increase the viscosity of human serum albumin to the level of effectively enhancing the expression of monocyte chemotactic protein-1 and endothelial nitric oxide synthase, which could promote microvascular perfusion. The hyperosmotic resuscitative agents including both 25% human serum albumin and PEGylated human serum albumins could greatly attenuate lung injury. No significant therapeutic advantages but some disadvantages were found for Y shaped poly(ethylene glycol) modification over linear poly(ethylene glycol) modification, such as causing the decrease of erythrocyte deformability. Linear high molecular weight site-specific PEGylated human serum albumin is recommended to be used as a hyperosmotic resuscitative agent.

Involvement of interleukin-8 in dialysis-related arthritis.

PubMed

Takayama, F; Miyazaki, T; Aoyama, I; Tsukushi, S; Sato, M; Yamazaki, C; Shimokata, K; Niwa, T

1998-04-01

To elucidate the role of interleukin (IL)-8, a chemotactic factor for neutrophils, in dialysis-related arthritis (DRA) of patients on long-term hemodialysis, the concentration of IL-8 was measured in the synovial fluids of DRA patients with acute arthralgia and joint swelling, and was compared with those in patients with rheumatoid arthritis (RA) and patients with osteoarthritis (OA). We noted a marked elevation of IL-8 in the joint fluids of patients with DRA and RA as compared with OA. Furthermore, to determine the role of IL-8 in synovitis, we examined the in vivo effect of intra-articular injection of human recombinant IL-8 on leukocyte infiltration into the joint space of rabbits. A single injection of IL-8 to the joints of rabbits induced rapid infiltration of neutrophils into the joint space and synovial tissues, which reached a maximum in four hours. The oral administration of indometacin farnesil (a prodrug that is converted to indomethacin after intestinal absorption) before the injection of IL-8 alleviated the infiltration of neutrophils. When human synovial cells were incubated with tumor necrosis factor (TNF)-alpha, the expression of IL-8 mRNA and IL-8 production in the cultured synovial cells were increased. The TNF-alpha-stimulated expression of IL-8 mRNA and IL-8 production in the cultured synovial cells were markedly inhibited by dexamethasone. In conclusion, IL-8 levels were markedly elevated in the joint fluids of patients with DRA. Interleukin-8 released from synovial cells may be an important factor to induce acute inflammation in DRA. Dexamethasone and indomethacin may be effective for DRA by inhibiting the production and chemotactic actions of IL-8, respectively.

Tissue Factor-Factor VIIa Complex Triggers Protease Activated Receptor 2-Dependent Growth Factor Release and Migration in Ovarian Cancer

PubMed Central

Chanakira, Alice; Westmark, Pamela R.; Ong, Irene M.; Sheehan, John P.

2017-01-01

Objective Enhanced tissue factor (TF) expression in epithelial ovarian cancer (EOC) is associated with aggressive disease. Our objective was to evaluate the role of the TF-factor VIIa-protease-activated receptor-2 (PAR-2) pathway in human EOC. Methods TCGA RNAseq data from EOC databases were analyzed for PAR expression. Cell and microparticle (MP) associated TF protein expression (Western blot) and MP-associated coagulant activity were determined in human EOC (SKOV-3, OVCAR-3 and CaOV-3) and control cell lines. PAR-1 and PAR-2 protein expression were similarly examined. The PAR dependence of VEGF-A release (ELISA) and chemotactic migration in response to FVIIa and cellular proliferation in response to thrombin was evaluated with small molecule antagonists. Results Relative mRNA expression consistently demonstrated PAR-2>PAR-1≫PAR-3/4 in multiple EOC datasets. Human EOC cell line lysates confirmed expression of TF, PAR-1 and PAR-2 proteins. MPs isolated from EOC cell lines demonstrated markedly enhanced (4–10 fold) TF coagulant activity relative to control cell lines. FVIIa induced a dose-dependent increase in VEGF-A release (2.5-3 fold) from EOC cell lines that was abrogated by the PAR-2 antagonist ENMD-1068. FVIIa treatment of CaOV-3 and OVCAR-3 cells resulted in increased chemotactic migration that was abolished by ENMD-1068. Thrombin induced dose-dependent EOC cell line proliferation was completely reversed by the PAR-1 antagonist vorapaxar. Small molecule antagonists had no effect on these phenotypes without protease present. Conclusions Enhanced activity of the TF-FVIIa-PAR-2 axis may contribute to the EOC progression via PAR-2 dependent signaling that supports an angiogenic and invasive phenotype and local thrombin generation supporting PAR-1 dependent proliferation. PMID:28148395

ENMD-1068, a protease-activated receptor 2 antagonist, inhibits the development of endometriosis in a mouse model.

PubMed

Wang, Yifeng; Lin, Min; Weng, Huinan; Wang, Xuefeng; Yang, Li; Liu, Fenghua

2014-06-01

Protease-activated receptor 2 plays an important role in the pathogenesis of endometriosis. We studied the effect of ENMD-1068, a protease-activated receptor 2 antagonist, on the development of endometriosis in a noninvasive fluorescent mouse model. A red fluorescent protein-expressing xenograft model of human endometriosis was created in nude mice. After endometriosis induction, the mice were injected intraperitoneally with either 25 mg/kg or 50 mg/kg ENMD-1068 or with 200 μL of the vehicle control daily for 5 days. The endometriotic lesions that developed in the mice were then counted, measured, and collected. The lesions were assessed for the production of interleukin 6 and monocyte chemotactic protein-1 by enzyme-linked immunosorbent assays and evaluated for the activation of nuclear factor-κB and the expression of vascular endothelial growth factor by immunohistochemical analyses. Cell proliferation and apoptosis were assessed by immunohistochemistry for Ki-67 and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, respectively. ENMD-1068 dose-dependently inhibited the development of endometriotic lesions (P < .05) without apparent toxicity to various organs of the treated mice. Consistently, ENMD-1068 dose-dependently inhibited the expression of interleukin 6 and nuclear factor-κB (P < .05) and cell proliferation (P < .05) in the lesions, as well as increased the percentage of apoptotic cells (P < .05). ENMD-1068 reduced the levels of monocyte chemotactic protein-1 and vascular endothelial growth factor in the lesions (P < .05), but not in a dose-dependent manner. Our study suggests that ENMD-1068 is effective in suppressing the growth of endometriosis, which might be attributed to the drug's antiangiogenic and antiinflammatory activities. Copyright © 2014 Mosby, Inc. All rights reserved.

Thalassospira sp. Isolated from the Oligotrophic Eastern Mediterranean Sea Exhibits Chemotaxis toward Inorganic Phosphate during Starvation▿†

PubMed Central

Hütz, Annemarie; Schubert, Karin; Overmann, Jörg

2011-01-01

The eastern Mediterranean Sea represents an ultraoligotrophic environment where soluble phosphate limits the growth of bacterioplankton. Correspondingly, genes coding for high-affinity phosphate uptake systems and for organophosphonate utilization are highly prevalent in the plankton metagenome. Chemotaxis toward inorganic phosphate constitutes an alternative strategy to cope with phosphate limitation, but so far has only been demonstrated for two bacterial pathogens and an archaeon, and not in any free-living planktonic bacterium. In the present study, bacteria affiliated with the genus Thalassospira were found to constitute a regular, low-abundance member of the bacterioplankton that can be detected throughout the water column of the eastern Mediterranean Sea. A representative (strain EM) was isolated in pure culture and exhibited a strong positive chemotaxis toward inorganic phosphate that was induced exclusively in phosphate-starved cultures. Phosphate-depleted cells were 2-fold larger than in exponentially growing cultures, and 43% of the cells retained their motility even during prolonged starvation over 10 days. In addition, Thalassospira sp. strain EM was chemotactically attracted by complex substrates (yeast extract and peptone), amino acids, and 2-aminoethylphosphonate but not by sugar monomers. Similarly to the isolate from the eastern Mediterranean, chemotaxis toward phosphate was observed in starved cultures of the other two available isolates of the genus, T. lucentensis DSM 14000T and T. profundimaris WP0211T. Although Thalassospira sp. represents only up to 1.2% of the total bacterioplankton community in the water column of the eastern Mediterranean Sea, its chemotactic behavior potentially leads to an acceleration of nutrient cycling and may also explain the persistence of marine copiotrophs in this extremely nutrient-limited environment. PMID:21602377

Thalassospira sp. isolated from the oligotrophic eastern Mediterranean Sea exhibits chemotaxis toward inorganic phosphate during starvation.

PubMed

Hütz, Annemarie; Schubert, Karin; Overmann, Jörg

2011-07-01

The eastern Mediterranean Sea represents an ultraoligotrophic environment where soluble phosphate limits the growth of bacterioplankton. Correspondingly, genes coding for high-affinity phosphate uptake systems and for organophosphonate utilization are highly prevalent in the plankton metagenome. Chemotaxis toward inorganic phosphate constitutes an alternative strategy to cope with phosphate limitation, but so far has only been demonstrated for two bacterial pathogens and an archaeon, and not in any free-living planktonic bacterium. In the present study, bacteria affiliated with the genus Thalassospira were found to constitute a regular, low-abundance member of the bacterioplankton that can be detected throughout the water column of the eastern Mediterranean Sea. A representative (strain EM) was isolated in pure culture and exhibited a strong positive chemotaxis toward inorganic phosphate that was induced exclusively in phosphate-starved cultures. Phosphate-depleted cells were 2-fold larger than in exponentially growing cultures, and 43% of the cells retained their motility even during prolonged starvation over 10 days. In addition, Thalassospira sp. strain EM was chemotactically attracted by complex substrates (yeast extract and peptone), amino acids, and 2-aminoethylphosphonate but not by sugar monomers. Similarly to the isolate from the eastern Mediterranean, chemotaxis toward phosphate was observed in starved cultures of the other two available isolates of the genus, T. lucentensis DSM 14000T and T. profundimaris WP0211T. Although Thalassospira sp. represents only up to 1.2% of the total bacterioplankton community in the water column of the eastern Mediterranean Sea, its chemotactic behavior potentially leads to an acceleration of nutrient cycling and may also explain the persistence of marine copiotrophs in this extremely nutrient-limited environment.

Secretion of S100A8, S100A9, and S100A12 by Neutrophils Involves Reactive Oxygen Species and Potassium Efflux.

PubMed

Tardif, Mélanie R; Chapeton-Montes, Julie Andrea; Posvandzic, Alma; Pagé, Nathalie; Gilbert, Caroline; Tessier, Philippe A

2015-01-01

S100A8/A9 (calprotectin) and S100A12 proinflammatory mediators are found at inflammatory sites and in the serum of patients with inflammatory or autoimmune diseases. These cytoplasmic proteins are secreted by neutrophils at sites of inflammation via alternative secretion pathways of which little is known. This study examined the nature of the stimuli leading to S100A8/A9 and S100A12 secretion as well as the mechanism involved in this alternative secretion pathway. Chemotactic agents, cytokines, and particulate molecules were used to stimulate human neutrophils. MSU crystals, PMA, and H2O2 induced the release of S100A8, S100A9, and S100A12 homodimers, as well as S100A8/A9 heterodimer. High concentrations of S100A8/A9 and S100A12 were secreted in response to nanoparticles like MSU, silica, TiO2, fullerene, and single-wall carbon nanotubes as well as in response to microbe-derived molecules, such as zymosan or HKCA. However, neutrophils exposed to the chemotactic factors fMLP failed to secrete S100A8/A9 or S100A12. Secretion of S100A8/A9 was dependent on the production of reactive oxygen species and required K(+) exchanges through the ATP-sensitive K(+) channel. Altogether, these findings suggest that S100A12 and S100A8/A9 are secreted independently either via distinct mechanisms of secretion or following the activation of different signal transduction pathways.

Secretion of S100A8, S100A9, and S100A12 by Neutrophils Involves Reactive Oxygen Species and Potassium Efflux

PubMed Central

Tardif, Mélanie R.; Chapeton-Montes, Julie Andrea; Posvandzic, Alma; Pagé, Nathalie; Gilbert, Caroline; Tessier, Philippe A.

2015-01-01

S100A8/A9 (calprotectin) and S100A12 proinflammatory mediators are found at inflammatory sites and in the serum of patients with inflammatory or autoimmune diseases. These cytoplasmic proteins are secreted by neutrophils at sites of inflammation via alternative secretion pathways of which little is known. This study examined the nature of the stimuli leading to S100A8/A9 and S100A12 secretion as well as the mechanism involved in this alternative secretion pathway. Chemotactic agents, cytokines, and particulate molecules were used to stimulate human neutrophils. MSU crystals, PMA, and H2O2 induced the release of S100A8, S100A9, and S100A12 homodimers, as well as S100A8/A9 heterodimer. High concentrations of S100A8/A9 and S100A12 were secreted in response to nanoparticles like MSU, silica, TiO2, fullerene, and single-wall carbon nanotubes as well as in response to microbe-derived molecules, such as zymosan or HKCA. However, neutrophils exposed to the chemotactic factors fMLP failed to secrete S100A8/A9 or S100A12. Secretion of S100A8/A9 was dependent on the production of reactive oxygen species and required K+ exchanges through the ATP-sensitive K+ channel. Altogether, these findings suggest that S100A12 and S100A8/A9 are secreted independently either via distinct mechanisms of secretion or following the activation of different signal transduction pathways. PMID:27057553

Sulforaphane and its methylcarbonyl analogs inhibit the LPS-stimulated inflammatory response in human monocytes through modulating cytokine production, suppressing chemotactic migration and phagocytosis in a NF-κB- and MAPK-dependent manner.

PubMed

Reddy, Shridhivya A; Shelar, Sandeep B; Dang, Truong-Minh; Lee, Baxter Neng-Cun; Yang, Hong; Ong, Siew-Min; Ng, Hui-Li; Chui, Wai-Keung; Wong, Siew-Cheng; Chew, Eng-Hui

2015-02-01

Sulforaphane [SF; 1-isothiocyanato-4-(methylsulfinyl)-butane], an aliphatic isothiocyanate (ITC) naturally derived from cruciferous vegetables and largely known for its chemopreventive potential also appears to possess anti-inflammatory potential. In this study, structural analogs of SF {compound 1 [1-isothiocyanato-4-(methylcarbonyl)-butane] and 2 [1-isothiocyanato-3-(methylcarbonyl)-propane]} containing a carbonyl group in place of the sulfinyl group in SF, were evaluated for their anti-inflammatory activities. In RAW 264.7 cells, the ITCs at non-toxic concentrations caused an inhibition of NO and prostaglandin E2 (PGE2) release through suppressing expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), as well as a reduction in matrix metalloproteinase-9 (MMP-9) expression, secretion and gelatinolytic activity. Further work performed on human monocytes isolated from blood of healthy donors revealed that the ITCs not only suppressed the expression and release of pro-inflammatory mediators IL-1β, IL-6, TNF-α and MMP-9, but also suppressed their antibody-independent phagocytic and chemotactic migratory abilities. These anti-inflammatory activities were mediated through suppression of the NF-κB and MAPK signaling pathways. In addition, the ITCs were revealed to interact with the cysteines in inhibitor of nuclear factor-κB kinase β subunit (IKKβ), which could contribute at least partly to the suppression of NF-κB signaling. In conclusion, results obtained in this study provide deeper insights into the anti-inflammatory properties of SF and its methylcarbonyl analogs and the underlying mechanisms. These compounds thus serve as promising candidates for clinical applications in controlling inflammatory conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Buprenorphine decreases the CCL2-mediated chemotactic response of monocytes.

PubMed

Carvallo, Loreto; Lopez, Lillie; Che, Fa-Yun; Lim, Jihyeon; Eugenin, Eliseo A; Williams, Dionna W; Nieves, Edward; Calderon, Tina M; Madrid-Aliste, Carlos; Fiser, Andras; Weiss, Louis; Angeletti, Ruth Hogue; Berman, Joan W

2015-04-01

Despite successful combined antiretroviral therapy, ∼ 60% of HIV-infected people exhibit HIV-associated neurocognitive disorders (HAND). CCL2 is elevated in the CNS of infected people with HAND and mediates monocyte influx into the CNS, which is critical in neuroAIDS. Many HIV-infected opiate abusers have increased neuroinflammation that may augment HAND. Buprenorphine is used to treat opiate addiction. However, there are few studies that examine its impact on HIV neuropathogenesis. We show that buprenorphine reduces the chemotactic phenotype of monocytes. Buprenorphine decreases the formation of membrane projections in response to CCL2. It also decreases CCL2-induced chemotaxis and mediates a delay in reinsertion of the CCL2 receptor, CCR2, into the cell membrane after CCL2-mediated receptor internalization, suggesting a mechanism of action of buprenorphine. Signaling pathways in CCL2-induced migration include increased phosphorylation of p38 MAPK and of the junctional protein JAM-A. We show that buprenorphine decreases these phosphorylations in CCL2-treated monocytes. Using DAMGO, CTAP, and Nor-BNI, we demonstrate that the effect of buprenorphine on CCL2 signaling is opioid receptor mediated. To identify additional potential mechanisms by which buprenorphine inhibits CCL2-induced monocyte migration, we performed proteomic analyses to characterize additional proteins in monocytes whose phosphorylation after CCL2 treatment was inhibited by buprenorphine. Leukosialin and S100A9 were identified and had not been shown previously to be involved in monocyte migration. We propose that buprenorphine limits CCL2-mediated monocyte transmigration into the CNS, thereby reducing neuroinflammation characteristic of HAND. Our findings underscore the use of buprenorphine as a therapeutic for neuroinflammation as well as for addiction. Copyright © 2015 by The American Association of Immunologists, Inc.

Lidocaine attenuates lipopolysaccharide-induced inflammatory responses in microglia.

PubMed

Yuan, Tong; Li, Zhiwen; Li, Xinbai; Yu, Gaoqi; Wang, Na; Yang, Xige

2014-11-01

Lidocaine has been used as a local anesthetic with anti-inflammatory properties, but its effects on neuroinflammation have not been well defined. In the present study, we investigated the prophylactic effects of lidocaine on lipopolysaccharide (LPS)-activated microglia and explored the underlying mechanisms. Microglial cells were incubated with or without 1 μg/mL LPS in the presence or absence of lidocaine, a p38 mitogen-activated protein kinase (p38 MAPK) inhibitor (SB203580), a nuclear factor-kappa B (NF-κB) inhibitor (pyrrolidine dithiocarbamate), or small interfering RNA. The protein and expression levels of inflammatory mediators, such as monocyte chemotactic protein 1, nitric oxide, prostaglandin E2, interleukin 1β, and tumor necrosis factor α were measured using enzyme-linked immunosorbent assays and real-time polymerase chain reaction. The effect of lidocaine on NF-κB and p38 MAPK activation was evaluated using enzyme-linked immunosorbent assays, Western blot analysis, and electrophoretic mobility shift assay. Lidocaine (≥2 μg/mL) significantly inhibited the release and expression of nitric oxide, monocyte chemotactic protein 1, prostaglandin E2, interleukin 1β, and tumor necrosis factor α in LPS-activated microglia. Treatment with lidocaine also significantly inhibited the phosphorylation of p38 MAPK and the nuclear translocation of NF-κB p50/p65, increased the protein levels of inhibitor kappa B-α. Furthermore, our study shows that the LPS-induced release of inflammatory mediators was suppressed by SB203580, pyrrolidine dithiocarbamate, and small interfering RNA. Prophylactic treatment with lidocaine inhibits LPS-induced release of inflammatory mediators from microglia, and these effects may be mediated by blockade of p38 MAPK and NF-κB signaling pathways. Copyright © 2014 Elsevier Inc. All rights reserved.

Delta 12-prostaglandin J2, a plasma metabolite of prostaglandin D2, causes eosinophil mobilization from the bone marrow and primes eosinophils for chemotaxis.

PubMed

Heinemann, Akos; Schuligoi, Rufina; Sabroe, Ian; Hartnell, Adele; Peskar, Bernhard A

2003-05-01

PGD(2), a major mast cell mediator, is a potent eosinophil chemoattractant and is thought to be involved in eosinophil recruitment to sites of allergic inflammation. In plasma, PGD(2) is rapidly transformed into its major metabolite delta(12)-PGJ(2), the effect of which on eosinophil migration has not yet been characterized. In this study we found that delta(12)-PGJ(2) was a highly effective chemoattractant and inducer of respiratory burst in human eosinophils, with the same efficacy as PGD(2), PGJ(2), or 15-deoxy-delta(12,14)-PGJ(2). Moreover, pretreatment of eosinophils with delta(12)-PGJ(2) markedly enhanced the chemotactic response to eotaxin, and in this respect delta(12)-PGJ(2) was more effective than PGD(2). delta(12)-PGJ(2)-induced facilitation of eosinophil migration toward eotaxin was not altered by specific inhibitors of intracellular signaling pathways relevant to the chemotactic response, phosphatidylinositol 3-kinase (LY-294002), mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (U-0126), or p38 mitogen-activated protein kinase (SB-202190). Desensitization studies using calcium flux suggested that delta(12)-PGJ(2) signaled through the same receptor, CRTH2, as PGD(2). Finally, delta(12)-PGJ(2) was able to mobilize mature eosinophils from the bone marrow of the guinea pig isolated perfused hind limb. Given that delta(12)-PGJ(2) is present in the systemic circulation at relevant levels, a role for this PGD(2) metabolite in eosinophil release from the bone marrow and in driving eosinophil recruitment to sites of inflammation appears conceivable.

Protective effects of intermittent hydrostatic pressure on osteoarthritic chondrocytes activated by bacterial endotoxin in vitro.

PubMed

Lee, Mel S; Ikenoue, Takashi; Trindade, Michael C D; Wong, Neal; Goodman, Stuart B; Schurman, David J; Smith, R Lane

2003-01-01

The role of continuous passive motion (CPM) in the management of septic arthritis and inflammatory arthritis remains of interest. CPM produces cyclic variations in intraarticular pressure that facilitates transport of fluid, nutrients, and solutes within and/or across the joint and stimulates chondrocyte metabolism. However, the precise mechanisms mediating the responses of chondrocytes to joint motion remain unclear. This study tested the hypothesis that dynamic mechanical loading counteracts effects of bacterial lipopolysaccharide (LPS), an inflammatory mediator, on chondrocyte metabolism. Intermittent hydrostatic pressure (IHP) (10 MPa for 4 h) was applied to human chondrocytes pretreated with LPS (1 microg/ml for 18 h). LPS activation of chondrocytes decreased mRNA signal levels of type II collagen by 67% and aggrecan by 56% and increased nitric oxide by 3.1-fold, monocyte chemotactic protein-1 mRNA signal levels by 6.5-fold, and matrix metalloproteinase-2 mRNA signal levels by 1.3-fold. Application of IHP to LPS-activated chondrocytes decreased nitric oxide synthase mRNA signal levels and nitric oxide levels in the culture medium. Exposure of LPS-activated chondrocytes to IHP upregulated type II collagen and aggrecan mRNA signal levels by 1.7-fold, relative to chondrocytes activated by LPS and maintained without loading. In addition, application of IHP decreased the upregulation in signal levels of monocyte chemotactic factor-1 and matrix metalloproteinase-2 following LPS activation by 45% and 15%, respectively. These data show that mechanical loading counteract effects of inflammatory agents, such as bacterial LPS, and suggest that postinfection sequelae are influenced by the presence or absence of joint loading.

An investigation on the chemotactic responses of different entomopathogenic nematode strains to mechanically damaged maize root volatile compounds.

PubMed

Laznik, Z; Trdan, S

2013-07-01

Entomopathogenic nematodes (EPNs) respond to a variety of stimuli when foraging. In a laboratory investigation, we tested the chemotactic responses of 8 EPN strains (Steinernema and Heterorhabditis) to three mechanically damaged maize root compounds (linalool, α-caryophyllene and β-caryophyllene). We hypothesized that the EPN directional response to the tested volatile compounds would vary among the species and volatile compound and may be related to foraging strategies. The nematodes with an intermediate foraging strategy (Steinernema feltiae) proved to be less active in their movement toward volatile compounds in a comparison with the ambushers (Steinernema carpocapsae) and cruisers (Steinernema kraussei and Heterorhabditis bacteriophora); β-caryophyllene was found to be the most attractive substance in our experiment. The results of our investigation showed that the cruisers were more attracted to β-caryophyllene than the ambushers and intermediates. The foraging strategy did not affect the movement of the IJs toward the other tested volatile compounds or the control. Our results suggest that the response to different volatile cues is more a strain-specific characteristic than a different host-searching strategy. Only S. carpocapsae strain B49 displayed an attraction to linalool, whereas S. kraussei showed a retarded reaction to β-caryophyllene and α-caryophyllene in our experiment. The EPN strains showed only a weak attraction to α-caryophyllene, suggesting that this volatile compound could not have an important role in the orientation of IJs to the damaged roots of maize plants. These results expand our knowledge of volatile compounds as the cues that may be used by EPNs for finding hosts or other aspects of navigation in the soil. Copyright © 2013 Elsevier Inc. All rights reserved.

The DRF motif of CXCR6 as chemokine receptor adaptation to adhesion.

PubMed

Koenen, Andrea; Babendreyer, Aaron; Schumacher, Julian; Pasqualon, Tobias; Schwarz, Nicole; Seifert, Anke; Deupi, Xavier; Ludwig, Andreas; Dreymueller, Daniela

2017-01-01

The CXC-chemokine receptor 6 (CXCR6) is a class A GTP-binding protein-coupled receptor (GPCRs) that mediates adhesion of leukocytes by interacting with the transmembrane cell surface-expressed chemokine ligand 16 (CXCL16), and also regulates leukocyte migration by interacting with the soluble shed variant of CXCL16. In contrast to virtually all other chemokine receptors with chemotactic activity, CXCR6 carries a DRF motif instead of the typical DRY motif as a key element in receptor activation and G protein coupling. In this work, modeling analyses revealed that the phenylalanine F3.51 in CXCR6 might have impact on intramolecular interactions including hydrogen bonds by this possibly changing receptor function. Initial investigations with embryonic kidney HEK293 cells and further studies with monocytic THP-1 cells showed that mutation of DRF into DRY does not influence ligand binding, receptor internalization, receptor recycling, and protein kinase B (AKT) signaling. Adhesion was slightly decreased in a time-dependent manner. However, CXCL16-induced calcium signaling and migration were increased. Vice versa, when the DRY motif of the related receptor CX3CR1 was mutated into DRF the migratory response towards CX3CL1 was diminished, indicating that the presence of a DRF motif generally impairs chemotaxis in chemokine receptors. Transmembrane and soluble CXCL16 play divergent roles in homeostasis, inflammation, and cancer, which can be beneficial or detrimental. Therefore, the DRF motif of CXCR6 may display a receptor adaptation allowing adhesion and cell retention by transmembrane CXCL16 but reducing the chemotactic response to soluble CXCL16. This adaptation may avoid permanent or uncontrolled recruitment of inflammatory cells as well as cancer metastasis.

The DRF motif of CXCR6 as chemokine receptor adaptation to adhesion

PubMed Central

Koenen, Andrea; Babendreyer, Aaron; Schumacher, Julian; Pasqualon, Tobias; Schwarz, Nicole; Seifert, Anke; Deupi, Xavier

2017-01-01

The CXC-chemokine receptor 6 (CXCR6) is a class A GTP-binding protein-coupled receptor (GPCRs) that mediates adhesion of leukocytes by interacting with the transmembrane cell surface-expressed chemokine ligand 16 (CXCL16), and also regulates leukocyte migration by interacting with the soluble shed variant of CXCL16. In contrast to virtually all other chemokine receptors with chemotactic activity, CXCR6 carries a DRF motif instead of the typical DRY motif as a key element in receptor activation and G protein coupling. In this work, modeling analyses revealed that the phenylalanine F3.51 in CXCR6 might have impact on intramolecular interactions including hydrogen bonds by this possibly changing receptor function. Initial investigations with embryonic kidney HEK293 cells and further studies with monocytic THP-1 cells showed that mutation of DRF into DRY does not influence ligand binding, receptor internalization, receptor recycling, and protein kinase B (AKT) signaling. Adhesion was slightly decreased in a time-dependent manner. However, CXCL16-induced calcium signaling and migration were increased. Vice versa, when the DRY motif of the related receptor CX3CR1 was mutated into DRF the migratory response towards CX3CL1 was diminished, indicating that the presence of a DRF motif generally impairs chemotaxis in chemokine receptors. Transmembrane and soluble CXCL16 play divergent roles in homeostasis, inflammation, and cancer, which can be beneficial or detrimental. Therefore, the DRF motif of CXCR6 may display a receptor adaptation allowing adhesion and cell retention by transmembrane CXCL16 but reducing the chemotactic response to soluble CXCL16. This adaptation may avoid permanent or uncontrolled recruitment of inflammatory cells as well as cancer metastasis. PMID:28267793

Mathematical modeling of chemotaxis and glial scarring around implanted electrodes

NASA Astrophysics Data System (ADS)

Silchenko, Alexander N.; Tass, Peter A.

2015-02-01

It is well known that the implantation of electrodes for deep brain stimulation or microelectrode probes for the recording of neuronal activity is always accompanied by the response of the brain’s immune system leading to the formation of a glial scar around the implantation sites. The implantation of electrodes causes massive release of adenosine-5‧-triphosphate (ATP) and different cytokines into the extracellular space and activates the microglia. The released ATP and the products of its hydrolysis, such as ADP and adenosine, become the main elements mediating chemotactic sensitivity and motility of microglial cells via subsequent activation of P2Y2,12 as well as A3A/A2A adenosine receptors. The size and density of an insulating sheath around the electrode, formed by microglial cells, are important criteria for the optimization of the signal-to-noise ratio during microelectrode recordings or parameters of electrical current delivered to the brain tissue. Here, we study a purinergic signaling pathway underlying the chemotactic motion of microglia towards implanted electrodes as well as the possible impact of an anti-inflammatory coating consisting of the interleukin-1 receptor antagonist. We present a model describing the formation of a stable aggregate around the electrode due to the joint chemo-attractive action of ATP and ADP and the mixed influence of extracellular adenosine. The bioactive coating is modeled as a source of chemo-repellent located near the electrode surface. The obtained analytical and numerical results allowed us to reveal the dependences of size and spatial location of the insulating sheath on the amount of released ATP and estimate the impact of immune suppressive coating on the scarring process.

Fy phenotype and gender determine plasma levels of monocyte chemotactic protein.

PubMed

Jilma-Stohlawetz, P; Homoncik, M; Drucker, C; Marsik, C; Rot, A; Mayr, W R; Seibold, B; Jilma, B

2001-03-01

In vitro studies indicate that the Fy blood group system antigens serve as receptors for chemokines such as monocyte chemotactic protein-1 (MCP-1) and RANTES. However, it is unclear whether subjects with the Fy(a-b-) phenotype exhibit altered clearance and hence altered plasma levels of chemo-kines, because they still express Fy on endothelial cells. To clarify a possible in vivo role of Fy on RBCs in the regulation of chemo-kine levels, healthy young volunteers of common Fy phenotypes were compared in a cross-sectional study. More than 90 percent of the 34 subjects of African origin were Fy(a-b-), one black volunteer was Fy(a+b-), and two were Fy(a-b+). As expected, all 65 white volunteers were positive for either Fy(a) and/or Fy(b). Unexpectedly, persons expressing either Fy(a) and/or Fy(b) had significantly higher plasma levels of MCP-1 than Fy(a-b-) volunteers (women: 154 vs. 110 ng/L, p<0.01; men: 179 vs. 169 ng/L, p = 0.03). Surprisingly, plasma levels of MCP-1 were found to be sex-dependent: median MCP-1 levels averaged 180 ng per L in men but only 139 ng per L in women (p<0.001). Further, MCP-1 levels decreased significantly throughout the menstrual cycle of 18 women studied longitudinally. MCP-1 levels are about 30 percent higher in men than in premenopausal women, and MCP-1 levels are also higher in persons with RBCs expressing Fy antigens than in Fy(a-b-) persons. These findings have direct implications for the concept and interpretation of clinical studies measuring MCP-1 levels; the role of the observed differences in MCP-1 levels for the pathogenesis of MCP-1-dependent diseases, such as atherosclerosis, merits further investigation.

Immune modulation of CD4+CD25+ regulatory T cells by zoledronic acid.

PubMed

Liu, Hsien; Wang, Shih-Han; Chen, Shin-Cheh; Chen, Ching-Ying; Lo, Jo-Lin; Lin, Tsun-Mei

2016-11-25

CD4 + CD25 + regulatory T (Treg) cells suppress tumor immunity by inhibiting immune cells. Manipulation of Treg cells represents a new strategy for cancer treatment. Zoledronic acid (ZA), a nitrogen-containing bisphosphonate, inhibits the expression of receptor activator of nuclear factor kappa-B ligand (RANKL) on osteoblasts to inhibit osteoclastogenesis. In a mouse model of bisphosphonate-related osteonecrosis of the jaw, administration of ZA suppressed Treg-cell activity and activated inflammatory Th17 cells. However, the interaction between ZA and Treg cells remained unclear. This study investigated the immune modulation of Treg cells by ZA. Flow cytometry was used to analyze the phenotypic and immunosuppressive characteristics of Treg cells treated with ZA. Chemotactic migration was evaluated using transwell assays. Quantitative real-time PCR (qRT-PCR) was used to investigate the effect of ZA on the expression of suppressive molecules by Treg cells. Proliferation of isolated Treg cells in culture was inhibited by ZA, although ZA did not induce apoptosis. qRT-PCR and flow cytometry showed that ZA significantly downregulated the expression of CCR4, CTLA4, PD-1 and RANKL on Treg cells. Chemotactic migration and immunosuppressive functions were also significantly attenuated in Treg cells pretreated with ZA, and these effects were dose-dependent. Co-culture with Treg cells significantly increased the migration rate of breast cancer cells, while pretreatment of Treg cells with ZA attenuated this effect. Our findings demonstrated that ZA acted as an immune modulator by significantly inhibiting the expansion, migration, immunosuppressive function and pro-metastatic ability of Treg cells. Immunomodulation of Treg cells by ZA represents a new strategy for cancer therapy.

Cytokines in relation to autoantibodies before onset of symptoms for systemic lupus erythematosus.

PubMed

Eriksson, C; Rantapää-Dahlqvist, S

2014-06-01

A number of cytokines and chemokines were analysed and related to autoantibodies in blood samples pre-dating the onset of symptoms of systemic lupus erythematosus. Thirty-five patients with systemic lupus erythematosus (American College of Rheumatology criteria) were identified as having donated blood samples, prior to symptom onset, to the Biobank of northern Sweden. Altogether, 140 age- and sex-matched controls were also identified. The concentrations of interferon-α, interleukin-4, interleukin-9, interleukin-10, interferon inducible protein-10 and monocyte chemotactic protein-1 were analysed using multiplex technology and related to autoantibodies (ANA, ENA, anti-dsDNA and anti-histone antibodies) analysed from the same blood sample. The interferon-γ inducible protein-10 levels were higher in the pre-symptomatic individuals than in controls (p < 0.05) and correlated with interferon-α (p < 0.01). The interferon-γ inducible protein-10 and interferon-α concentrations were significantly increased in individuals positive for autoantibodies: interferon-γ inducible protein-10 for ANA; anti-SSA/Ro and anti-Jo-1 antibodies; interferon-α with anti-SSB/La antibodies. The levels of interleukin-10, interferon-γ inducible protein-10 and monocyte chemotactic protein-1 increased significantly from the pre-symptomatic individuals to after onset of systemic lupus erythematosus. An increased concentration of interferon-γ inducible protein-10 pre-dated the onset of systemic lupus erythematosus and was related to autoantibodies before the onset of disease. The levels of interferon-γ inducible protein-10 and interferon-α were correlated. These findings support the proposal that the interferon system is important early in the pathogenesis of systemic lupus erythematosus and autoantibody formation. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Synergic production of neutrophil chemotactic activity by colonic epithelial cells and eosinophils.

PubMed

Dent, Gordon; Loweth, Sam C; Hasan, Anwar Matar; Leslie, Fiona M

2014-10-01

The presence of eosinophils in the lumen and mucosa of the intestine is characteristic of both ulcerative colitis (UC) and Crohn's disease (CD). There is evidence of eosinophil activation in the intestine during acute inflammatory episodes of these diseases; these episodes are also characterized by an influx of neutrophils, which have the potential to cause extensive tissue damage. We undertook a study to determine whether eosinophils in contact with colonic epithelial cells produce factors that may attract neutrophils in response to immunological stimulation. Neutrophil chemotactic activity (NCA) and concentrations of three neutrophil-attracting CXC chemokines - CXCL1 (Groα), CXCL5 (Ena78) and CXCL8 (IL8) - were measured in supernatants of T84 colonic epithelial cells and blood eosinophils or eosinophil-like myeloid leukaemia cells (AML14.3D10), alone or in combination. Cells were stimulated with serum-opsonized zymosan (OZ) particles. NCA (P<0.005) and CXCL5 levels (P<0.05) in the supernatants of OZ-stimulated epithelial/eosinophil co-cultures were significantly higher than in the supernatants of either cell type alone. Release of CXCL1 (P<0.05) and CXCL8 (P<0.01) from OZ-stimulated co-culture supernatants was significantly higher than from OZ-stimulated eosinophils but not higher than from OZ-stimulated epithelial cells. Eosinophils and colonic epithelial cells exhibit synergy in production of neutrophil chemoattractants in response to immunological stimulation. This may represent a mechanism for exaggerated recruitment of neutrophils to the intestine in response to acute infection in conditions that are characterized by the presence of eosinophils in the bowel. Copyright © 2014 Elsevier GmbH. All rights reserved.

Angiostatic and chemotactic activities of the CXC chemokine CXCL4L1 (platelet factor-4 variant) are mediated by CXCR3

PubMed Central

Struyf, Sofie; Salogni, Laura; Burdick, Marie D.; Vandercappellen, Jo; Gouwy, Mieke; Noppen, Sam; Proost, Paul; Opdenakker, Ghislain; Parmentier, Marc; Gerard, Craig; Sozzani, Silvano; Strieter, Robert M.

2011-01-01

We investigated possible cellular receptors for the human CXC chemokine platelet factor-4 variant/CXCL4L1, a potent inhibitor of angiogenesis. We found that CXCL4L1 has lower affinity for heparin and chondroitin sulfate-E than platelet factor-4 (CXCL4) and showed that CXCL10 and CXCL4L1 could displace each other on microvascular endothelial cells. Labeled CXCL4L1 also bound to CXCR3A- and CXCR3B-transfectants and was displaced by CXCL4L1, CXCL4, and CXCL10. The CXCL4L1 anti-angiogenic activity was blocked by anti-CXCR3 antibodies (Abs) in the Matrigel and cornea micropocket assays. CXCL4L1 application in CXCR3−/− or in wild-type mice treated with neutralizing anti-CXCR3 Abs, resulted in reduced inhibitory activity of CXCL4L1 on tumor growth and vascularization of Lewis lung carcinoma. Furthermore, CXCL4L1 and CXCL4 chemoattracted activated T cells, human natural killer cells, and human immature dendritic cells (DCs). Migration of DCs toward CXCL4 and CXCL4L1 was desensitized by preincubation with CXCL10 and CXCL11, inhibited by pertussis toxin, and neutralized by anti-CXCR3 Abs. Chemotaxis of T cells, natural killer cells, and DCs is likely to contribute to the antitumoral action. However, the in vivo data indicate that the angiostatic property of CXCL4L1 is equally important in retarding tumor growth. Thus, both CXCR3A and CXCR3B are implicated in the chemotactic and vascular effects of CXCL4L1. PMID:20980681

Angiostatic and chemotactic activities of the CXC chemokine CXCL4L1 (platelet factor-4 variant) are mediated by CXCR3.

PubMed

Struyf, Sofie; Salogni, Laura; Burdick, Marie D; Vandercappellen, Jo; Gouwy, Mieke; Noppen, Sam; Proost, Paul; Opdenakker, Ghislain; Parmentier, Marc; Gerard, Craig; Sozzani, Silvano; Strieter, Robert M; Van Damme, Jo

2011-01-13

We investigated possible cellular receptors for the human CXC chemokine platelet factor-4 variant/CXCL4L1, a potent inhibitor of angiogenesis. We found that CXCL4L1 has lower affinity for heparin and chondroitin sulfate-E than platelet factor-4 (CXCL4) and showed that CXCL10 and CXCL4L1 could displace each other on microvascular endothelial cells. Labeled CXCL4L1 also bound to CXCR3A- and CXCR3B-transfectants and was displaced by CXCL4L1, CXCL4, and CXCL10. The CXCL4L1 anti-angiogenic activity was blocked by anti-CXCR3 antibodies (Abs) in the Matrigel and cornea micropocket assays. CXCL4L1 application in CXCR3(-/-) or in wild-type mice treated with neutralizing anti-CXCR3 Abs, resulted in reduced inhibitory activity of CXCL4L1 on tumor growth and vascularization of Lewis lung carcinoma. Furthermore, CXCL4L1 and CXCL4 chemoattracted activated T cells, human natural killer cells, and human immature dendritic cells (DCs). Migration of DCs toward CXCL4 and CXCL4L1 was desensitized by preincubation with CXCL10 and CXCL11, inhibited by pertussis toxin, and neutralized by anti-CXCR3 Abs. Chemotaxis of T cells, natural killer cells, and DCs is likely to contribute to the antitumoral action. However, the in vivo data indicate that the angiostatic property of CXCL4L1 is equally important in retarding tumor growth. Thus, both CXCR3A and CXCR3B are implicated in the chemotactic and vascular effects of CXCL4L1.

Monocyte Chemotactic Protein-1 (MCP-1) and Growth Factors Called into Question as Markers of Prolonged Psychosocial Stress

PubMed Central

Jonsdottir, Ingibjörg H.; Hägg, Daniel A.; Glise, Kristina; Ekman, Rolf

2009-01-01

Background Psychosocial stress is becoming a major contributor to increased mental ill-health and sick leave in many countries. Valid markers of chronic stress would be valuable for diagnostic and prognostic purposes. A recent study suggested monocyte chemotactic protein-1 (MCP-1), epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) as markers of chronic stress. We aimed to confirm these potential biomarkers of prolonged psychosocial stress in female patients. Methodology/Principal Findings Circulating levels of MCP-1, EGF and VEGF, along with several other cytokines, were measured in plasma from 42 female patients suffering from exhaustion due to prolonged psychosocial stress and 42 control subjects, using a protein biochip immunoassay. There were no significant differences between patients and controls in any of the cytokines or growth factors analyzed. Furthermore, when using a different protein bioassay and reanalyzing MCP-1 and VEGF in the same samples, markedly different levels were obtained. To further explore if inflammation is present in patients with exhaustion, the classical inflammatory marker C-reactive protein (CRP) was measured in another group of patients (n = 89) and controls (n = 88) showing a small but significant increase of CRP levels in the patients. Conclusions/Significance MCP-1, EGF and VEGF may not be suitable markers of prolonged psychosocial stress as previously suggested. Furthermore, significant differences were obtained when using two different protein assays measuring the same samples, indicating that comparing studies where different analytic techniques have been used might be difficult. Increased levels of CRP indicate that low-grade inflammation might be present in patients with exhaustion due to prolonged stress exposure but this inflammation does not seem to be reflected by increase in circulating MCP-1 or other cytokines measured. PMID:19888340

The calcium-activated potassium channel KCa3.1 plays a central role in the chemotactic response of mammalian neutrophils.

PubMed

Henríquez, C; Riquelme, T T; Vera, D; Julio-Kalajzić, F; Ehrenfeld, P; Melvin, J E; Figueroa, C D; Sarmiento, J; Flores, C A

2016-01-01

Neutrophils are the first cells to arrive at sites of injury. Nevertheless, many inflammatory diseases are characterized by an uncontrolled infiltration and action of these cells. Cell migration depends on volume changes that are governed by ion channel activity, but potassium channels in neutrophil have not been clearly identified. We aim to test whether KCa3.1 participates in neutrophil migration and other relevant functions of the cell. Cytometer and confocal measurements to determine changes in cell volume were used. Cells isolated from human, mouse and horse were tested for KCa3.1-dependent chemotaxis. Chemokinetics, calcium handling and release of reactive oxygen species were measured to determine the role of KCa3.1 in those processes. A mouse model was used to test for neutrophil recruitment after acute lung injury in vivo. We show for the first time that KCa3.1 is expressed in mammalian neutrophils. When the channel is inhibited by a pharmacological blocker or by genetic silencing, it profoundly affects cell volume regulation, and chemotactic and chemokinetic properties of the cells. We also demonstrated that pharmacological inhibition of KCa3.1 did not affect calcium entry or reactive oxygen species production in neutrophils. Using a mouse model of acute lung injury, we observed that Kca3.1(-/-) mice are significantly less effective at recruiting neutrophils into the site of inflammation. These results demonstrate that KCa3.1 channels are key actors in the migration capacity of neutrophils, and its inhibition did not affect other relevant cellular functions. © 2015 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Anti-inflammatory effects of traditional mixed extract of medicinal herbs (MEMH) on monosodium urate crystal-induced gouty arthritis.

PubMed

Nam, Ju-Suk; Jagga, Supriya; Sharma, Ashish Ranjan; Lee, Joon-Hee; Park, Jong Bong; Jung, Jun-Sub; Lee, Sang-Soo

2017-08-01

Korean oriental medicine prescription is widely used for the treatment of gouty diseases. In the present study, we investigated anti-inflammatory effects of modified Korean herbal formulation, mixed extract of medicinal herbs (MEMH), and its modulatory effects on inflammatory mediators associated with gouty arthritis. Both in vitro and in vivo studies were carried out to assess the anti-inflammatory efficacy of MEMH on monosodium urate (MSU) crystals-induced gouty inflammation. MSU crystals stimulated human chondrosarcoma cell line, SW1353, and human primary chondrocytes were treated with MEMH in vitro. The expression levels of pro-inflammatory mediators and metalloproteases were analyzed. The effect of MEMH on NFκB signaling pathway in SW1353 cells was examined. Effect of MEMH on the mRNA expression level of pro-inflammatory mediators and chemotactic factor from human monocytic cell line, THP-1, was also analyzed. The probable role of MEMH in the differentiation process of osteoblast like cells, SaOS-2, after MSU treatment was also observed. To investigate the effects of MEMH in vivo, MSU crystals-induced ankle arthritic model was established. Histopathological changes in affected joints and plasma levels of pro-inflammatory mediators (IL-1β and TNFα) were recorded. MEMH inhibited NFκB signaling pathway and COX-2 protein expression in chondrocytes. MSU-induced mRNA expressions of pro-inflammatory mediators and chemotactic cytokines were suppressed by MEMH. In MSU crystals-induced ankle arthritic mouse model, administration of MEMH relieved inflammatory symptoms and decreased the plasma levels of IL-1β and TNFα. The results indicated that MEMH can effectively inhibit the expression of inflammatory mediators in gouty arthritis, demonstrating its potential for treating gouty arthritis. Copyright © 2017 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

The effects of weekly augmentation therapy in patients with PiZZ α1-antitrypsin deficiency

PubMed Central

Schmid, ST; Koepke, J; Dresel, M; Hattesohl, A; Frenzel, E; Perez, J; Lomas, DA; Miranda, E; Greulich, T; Noeske, S; Wencker, M; Teschler, H; Vogelmeier, C; Janciauskiene, S; Koczulla, AR

2012-01-01

Background The major concept behind augmentation therapy with human α1-antitrypsin (AAT) is to raise the levels of AAT in patients with protease inhibitor phenotype ZZ (Glu342Lys)-inherited AAT deficiency and to protect lung tissues from proteolysis and progression of emphysema. Objective To evaluate the short-term effects of augmentation therapy (Prolastin®) on plasma levels of AAT, C-reactive protein, and chemokines/cytokines. Materials and methods Serum and exhaled breath condensate were collected from individuals with protease inhibitor phenotype ZZ AAT deficiency-related emphysema (n = 12) on the first, third, and seventh day after the infusion of intravenous Prolastin. Concentrations of total and polymeric AAT, interleukin-8 (IL-8), monocyte chemotactic protein-1, IL-6, tumor necrosis factor-α, vascular endothelial growth factor, and C-reactive protein were determined. Blood neutrophils and primary epithelial cells were also exposed to Prolastin (1 mg/mL). Results There were significant fluctuations in serum (but not in exhaled breath condensate) levels of AAT polymers, IL-8, monocyte chemotactic protein-1, IL-6, tumor necrosis factor-α, and vascular endothelial growth factor within a week of augmentation therapy. In general, augmented individuals had higher AAT and lower serum levels of IL-8 than nonaugmented subjects. Prolastin added for 3 hours to neutrophils from protease inhibitor phenotype ZZ individuals in vitro reduced IL-8 release but showed no effect on cytokine/chemokine release from human bronchial epithelial cells. Conclusion Within a week, augmentation with Prolastin induced fluctuations in serum levels of AAT polymers and cytokine/chemokines but specifically lowered IL-8 levels. It remains to be determined whether these effects are related to the Prolastin preparation per se or to the therapeutic efficacy of augmentation with AAT. PMID:23055718

The impact of odor–reward memory on chemotaxis in larval Drosophila

PubMed Central

Schleyer, Michael; Reid, Samuel F.; Pamir, Evren; Saumweber, Timo; Paisios, Emmanouil; Davies, Alexander

2015-01-01

How do animals adaptively integrate innate with learned behavioral tendencies? We tackle this question using chemotaxis as a paradigm. Chemotaxis in the Drosophila larva largely results from a sequence of runs and oriented turns. Thus, the larvae minimally need to determine (i) how fast to run, (ii) when to initiate a turn, and (iii) where to direct a turn. We first report how odor-source intensities modulate these decisions to bring about higher levels of chemotactic performance for higher odor-source intensities during innate chemotaxis. We then examine whether the same modulations are responsible for alterations of chemotactic performance by learned odor “valence” (understood throughout as level of attractiveness). We find that run speed (i) is neither modulated by the innate nor by the learned valence of an odor. Turn rate (ii), however, is modulated by both: the higher the innate or learned valence of the odor, the less often larvae turn whenever heading toward the odor source, and the more often they turn when heading away. Likewise, turning direction (iii) is modulated concordantly by innate and learned valence: turning is biased more strongly toward the odor source when either innate or learned valence is high. Using numerical simulations, we show that a modulation of both turn rate and of turning direction is sufficient to account for the empirically found differences in preference scores across experimental conditions. Our results suggest that innate and learned valence organize adaptive olfactory search behavior by their summed effects on turn rate and turning direction, but not on run speed. This work should aid studies into the neural mechanisms by which memory impacts specific aspects of behavior. PMID:25887280

Hydrodynamic shear shows distinct roles for LFA-1 and Mac-1 in neutrophil adhesion to intercellular adhesion molecule-1.

PubMed

Neelamegham, S; Taylor, A D; Burns, A R; Smith, C W; Simon, S I

1998-09-01

The binding of neutrophil beta2 integrin to intercellular adhesion molecule-1 (ICAM-1) expressed on the inflamed endothelium is critical for neutrophil arrest at sites of tissue inflammation. To quantify the strength and kinetics of this interaction, we measured the adhesion between chemotactically stimulated neutrophils and ICAM-1-transfected mouse cells (E3-ICAM) in suspension in a cone-plate viscometer at shear rates typical of venular blood flow (100 s-1 to 500 s-1). The kinetics of aggregation were fit with a mathematical model based on two-body collision theory. This enabled estimation of adhesion efficiency, defined as the probability with which collisions between cells resulted in firm adhesion. The efficiency of beta2-integrin-dependent adhesion was highest ( approximately 0.2) at 100 s-1 and it decreased to approximately zero at 400 s-1. Both LFA-1 and Mac-1 contributed equally to adhesion efficiency over the initial 30 seconds of stimulation, but adhesion was entirely Mac-1-dependent by 120 seconds. Two hydrodynamic parameters were observed to influence integrin-dependent adhesion efficiency: the level of shear stress and the intercellular contact duration. Below a critical shear stress (<2 dyn/cm2), contact duration predominantly limited adhesion efficiency. The estimated minimum contact duration for beta2-integrin binding was approximately 6.5 ms. Above the critical shear stress (>2 dyn/cm2), the efficiency of neutrophil adhesion to E3-ICAM was limited by both the contact duration and the tensile stress. We conclude that at low shear, neutrophil adhesion is modulated independently through either LFA-1 or Mac-1, which initially contribute with equal efficiency, but differ over the duration of chemotactic stimulation. Copyright 1998 by The American Society of Hematology.

Evidence for chemokine synergy during neutrophil migration in ARDS.

PubMed

Williams, Andrew E; José, Ricardo J; Mercer, Paul F; Brealey, David; Parekh, Dhruv; Thickett, David R; O'Kane, Cecelia; McAuley, Danny F; Chambers, Rachel C

2017-01-01

Acute respiratory distress syndrome (ARDS) is a life-threatening condition characterised by pulmonary oedema, respiratory failure and severe inflammation. ARDS is further characterised by the recruitment of neutrophils into the lung interstitium and alveolar space. The factors that regulate neutrophil infiltration into the inflamed lung and our understanding of the pathomechanisms in ARDS remain incomplete. This study aimed at determining the role of the chemokine (C-C motif) ligand (CCL)2 and CCL7 in ARDS. CCL2 and CCL7 protein levels were measured in bronchoalveolar lavage (BAL) fluid obtained from lipopolysaccharide(LPS)-challenged human volunteers and two separate cohorts of patients with ARDS. Neutrophil chemotaxis to ARDS BAL fluid was evaluated and the contribution of each was assessed and compared with chemokine (C-X-C motif) ligand 8 (CXCL8). Chemokine receptor expression on neutrophils from blood or BAL fluid of patients with ARDS was analysed by flow cytometry. CCL2 and CCL7 were significantly elevated in BAL fluid recovered from LPS-challenged volunteers and patients with ARDS. BAL fluid from patients with ARDS was highly chemotactic for human neutrophils and neutralising either CCL2 or CCL7 attenuated the neutrophil chemotactic response. Moreover, CCL2 and CCL7 synergised with CXCL8 to promote neutrophil migration. Furthermore, neutrophils isolated from the blood or BAL fluid differentially regulated the cell surface expression of chemokine (C-X-C motif) receptor 1 and C-C chemokine receptor type 2 during ARDS. This study highlights important inflammatory chemokines involved in regulating neutrophil migration, which may have potential value as therapeutic targets for the treatment of ARDS. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Evidence for chemokine synergy during neutrophil migration in ARDS

PubMed Central

Williams, Andrew E; José, Ricardo J; Mercer, Paul F; Brealey, David; Parekh, Dhruv; Thickett, David R; O'Kane, Cecelia; McAuley, Danny F; Chambers, Rachel C

2017-01-01

Background Acute respiratory distress syndrome (ARDS) is a life-threatening condition characterised by pulmonary oedema, respiratory failure and severe inflammation. ARDS is further characterised by the recruitment of neutrophils into the lung interstitium and alveolar space. Objectives The factors that regulate neutrophil infiltration into the inflamed lung and our understanding of the pathomechanisms in ARDS remain incomplete. This study aimed at determining the role of the chemokine (C-C motif) ligand (CCL)2 and CCL7 in ARDS. Methods CCL2 and CCL7 protein levels were measured in bronchoalveolar lavage (BAL) fluid obtained from lipopolysaccharide(LPS)-challenged human volunteers and two separate cohorts of patients with ARDS. Neutrophil chemotaxis to ARDS BAL fluid was evaluated and the contribution of each was assessed and compared with chemokine (C-X-C motif) ligand 8 (CXCL8). Chemokine receptor expression on neutrophils from blood or BAL fluid of patients with ARDS was analysed by flow cytometry. Results CCL2 and CCL7 were significantly elevated in BAL fluid recovered from LPS-challenged volunteers and patients with ARDS. BAL fluid from patients with ARDS was highly chemotactic for human neutrophils and neutralising either CCL2 or CCL7 attenuated the neutrophil chemotactic response. Moreover, CCL2 and CCL7 synergised with CXCL8 to promote neutrophil migration. Furthermore, neutrophils isolated from the blood or BAL fluid differentially regulated the cell surface expression of chemokine (C-X-C motif) receptor 1 and C-C chemokine receptor type 2 during ARDS. Conclusion This study highlights important inflammatory chemokines involved in regulating neutrophil migration, which may have potential value as therapeutic targets for the treatment of ARDS. PMID:27496101

Chemometric analysis of Hymenoptera toxins and defensins: A model for predicting the biological activity of novel peptides from venoms and hemolymph.

PubMed

Saidemberg, Daniel M; Baptista-Saidemberg, Nicoli B; Palma, Mario S

2011-09-01

When searching for prospective novel peptides, it is difficult to determine the biological activity of a peptide based only on its sequence. The "trial and error" approach is generally laborious, expensive and time consuming due to the large number of different experimental setups required to cover a reasonable number of biological assays. To simulate a virtual model for Hymenoptera insects, 166 peptides were selected from the venoms and hemolymphs of wasps, bees and ants and applied to a mathematical model of multivariate analysis, with nine different chemometric components: GRAVY, aliphaticity index, number of disulfide bonds, total residues, net charge, pI value, Boman index, percentage of alpha helix, and flexibility prediction. Principal component analysis (PCA) with non-linear iterative projections by alternating least-squares (NIPALS) algorithm was performed, without including any information about the biological activity of the peptides. This analysis permitted the grouping of peptides in a way that strongly correlated to the biological function of the peptides. Six different groupings were observed, which seemed to correspond to the following groups: chemotactic peptides, mastoparans, tachykinins, kinins, antibiotic peptides, and a group of long peptides with one or two disulfide bonds and with biological activities that are not yet clearly defined. The partial overlap between the mastoparans group and the chemotactic peptides, tachykinins, kinins and antibiotic peptides in the PCA score plot may be used to explain the frequent reports in the literature about the multifunctionality of some of these peptides. The mathematical model used in the present investigation can be used to predict the biological activities of novel peptides in this system, and it may also be easily applied to other biological systems. Copyright © 2011 Elsevier Inc. All rights reserved.

Method of degrading pollutants in soil

DOEpatents

Hazen, Terry C.; Lopez-De-Victoria, Geralyne

1994-01-01

A method and system for enhancing the motility of microorganisms by placing an effective amount of chlorinated hydrocarbons, preferably chlorinated alkenes, and most preferably trichloroethylene in spaced relation to the microbes so that the surprisingly strong, monomodal, chemotactic response of the chlorinated hydrocarbon on subsurface microbes can draw the microbes away from or towards and into a substance, as desired. In remediation of groundwater pollution, for example, TCE can be injected into the plume to increase the population of microbes at the plume whereby the plume can be more quickly degraded. A TCE-degrading microbe, such as Welchia alkenophilia, can be used to degrade the TCE following the degradation of the original pollutant.

Gc protein (vitamin D-binding protein): Gc genotyping and GcMAF precursor activity.

PubMed

Nagasawa, Hideko; Uto, Yoshihiro; Sasaki, Hideyuki; Okamura, Natsuko; Murakami, Aya; Kubo, Shinichi; Kirk, Kenneth L; Hori, Hitoshi

2005-01-01

The Gc protein (human group-specific component (Gc), a vitamin D-binding protein or Gc globulin), has important physiological functions that include involvement in vitamin D transport and storage, scavenging of extracellular G-actin, enhancement of the chemotactic activity of C5a for neutrophils in inflammation and macrophage activation (mediated by a GalNAc-modified Gc protein (GcMAF)). In this review, the structure and function of the Gc protein is focused on especially with regard to Gc genotyping and GcMAF precursor activity. A discussion of the research strategy "GcMAF as a target for drug discovery" is included, based on our own research.

Chemopreventive Strategies for Inflammation-Related Carcinogenesis: Current Status and Future Direction.

PubMed

Kanda, Yusuke; Osaki, Mitsuhiko; Okada, Futoshi

2017-04-19

A sustained and chronically-inflamed environment is characterized by the presence of heterogeneous inflammatory cellular components, including neutrophils, macrophages, lymphocytes and fibroblasts. These infiltrated cells produce growth stimulating mediators (inflammatory cytokines and growth factors), chemotactic factors (chemokines) and genotoxic substances (reactive oxygen species and nitrogen oxide) and induce DNA damage and methylation. Therefore, chronic inflammation serves as an intrinsic niche for carcinogenesis and tumor progression. In this article, we summarize the up-to-date findings regarding definitive/possible causes and mechanisms of inflammation-related carcinogenesis derived from experimental and clinical studies. We also propose 10 strategies, as well as candidate agents for the prevention of inflammation-related carcinogenesis.

A surgeons' guide to renal transplant immunopathology, immunology, and immunosuppression.

PubMed

Gaber, Lillian W; Knight, Richard J; Patel, Samir J

2013-12-01

The response to allografting involves adaptive and innate immune mechanisms. In the adaptive system, activated T cells differentiate to cytotoxic effectors that attack the graft and trigger B cells to differentiation to plasma cells that produce anti-HLA antibodies. The innate immune system recognizes antigens in a non-specific manner and recruits immune cells to the graft through the productions of chemotactic factors, and activation of cytokines and the complement cascade. In the kidney the tubules and the endothelium are the targets of the rejection response. Immune suppression is effective in modulating the adaptive immune system effect on graft histology. Copyright © 2013 Elsevier Inc. All rights reserved.

Method of degrading pollutants in soil

DOEpatents

Hazen, T.C.; Lopez-De-Victoria, G.

1994-07-05

Disclosed are a method and system for enhancing the motility of microorganisms. This is accomplished by placing an effective amount of chlorinated hydrocarbons, preferably chlorinated alkenes, and most preferably trichloroethylene in spaced relation to the microbes so that the surprisingly strong, monomodal, chemotactic response of the chlorinated hydrocarbon on subsurface microbes can draw the microbes away from or towards and into a substance, as desired. In remediation of groundwater pollution, for example, TCE can be injected into the plume to increase the population of microbes at the plume whereby the plume can be more quickly degraded. A TCE-degrading microbe, such as Welchia alkenophilia, can be used to degrade the TCE following the degradation of the original pollutant. 5 figures.

Bacterial chemoreceptors: high-performance signaling in networked arrays.

PubMed

Hazelbauer, Gerald L; Falke, Joseph J; Parkinson, John S

2008-01-01

Chemoreceptors are crucial components in the bacterial sensory systems that mediate chemotaxis. Chemotactic responses exhibit exquisite sensitivity, extensive dynamic range and precise adaptation. The mechanisms that mediate these high-performance functions involve not only actions of individual proteins but also interactions among clusters of components, localized in extensive patches of thousands of molecules. Recently, these patches have been imaged in native cells, important features of chemoreceptor structure and on-off switching have been identified, and new insights have been gained into the structural basis and functional consequences of higher order interactions among sensory components. These new data suggest multiple levels of molecular interactions, each of which contribute specific functional features and together create a sophisticated signaling device.

Evaluation of ⁹⁹(m)Tc-labeled antibiotics for infection detection.

PubMed

Lambrecht, Fatma Yurt

2011-01-01

One of the fields of research in nuclear medicine is the development of new radiopharmaceuticals for imaging infection and inflammation in humans. For this development, several antimicrobial peptides, antibiotics, antibiotic peptide and chemotactic peptides, etc., have been radiolabeled with different radionuclides (⁶⁷Ga, ⁹⁹(m)Tc, ¹¹¹In, ¹⁸F, ¹³¹I, etc.) and their imaging potentials studied. Actually, it is very important to distinguish between infection and inflammation. In this respect, radiolabeled antibiotics have advantages because many of the properties of the ideal infection-specific agent through antibiotics localizes in infection site. In this review, only ⁹⁹(m)Tc-labeled antibiotics are evaluated and discussed.

Contractile Skeletal Muscle Cells Cultured with a Conducting Soft Wire for Effective, Selective Stimulation.

PubMed

Nagamine, Kuniaki; Sato, Hirotaka; Kai, Hiroyuki; Kaji, Hirokazu; Kanzaki, Makoto; Nishizawa, Matsuhiko

2018-02-02

Contractile skeletal muscle cells were cultured so as to wrap around an electrode wire to enable their selective stimulation even when they were co-cultured with other electrically-excitable cells. Since the electrode wire was composed of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and polyurethane (PU), which is soft and highly capacitive (~10 mF cm -2 ), non-faradaic electrical stimulation with charge/discharge currents could be applied to the surrounding cells without causing significant damage even for longer periods (more than a week). The advantage of this new culture system was demonstrated in the study of chemotactic interaction of monocytes and skeletal muscle cells via myokines.

Bacterial chemoreceptors: high-performance signaling in networked arrays

PubMed Central

Hazelbauer, Gerald L.; Falke, Joseph J.; Parkinson, John S.

2010-01-01

Chemoreceptors are crucial components in the bacterial sensory systems that mediate chemotaxis. Chemotactic responses exhibit exquisite sensitivity, extensive dynamic range and precise adaptation. The mechanisms that mediate these high-performance functions involve not only actions of individual proteins but also interactions among clusters of components, localized in extensive patches of thousands of molecules. Recently, these patches have been imaged in native cells, important features of chemoreceptor structure and on–off switching have been identified, and new insights have been gained into the structural basis and functional consequences of higher order interactions among sensory components. These new data suggest multiple levels of molecular interactions, each of which contribute specific functional features and together create a sophisticated signaling device. PMID:18165013

Differential targeting of Gbetagamma-subunit signaling with small molecules.

PubMed

Bonacci, Tabetha M; Mathews, Jennifer L; Yuan, Chujun; Lehmann, David M; Malik, Sundeep; Wu, Dianqing; Font, Jose L; Bidlack, Jean M; Smrcka, Alan V

2006-04-21

G protein betagamma subunits have potential as a target for therapeutic treatment of a number of diseases. We performed virtual docking of a small-molecule library to a site on Gbetagamma subunits that mediates protein interactions. We hypothesized that differential targeting of this surface could allow for selective modulation of Gbetagamma subunit functions. Several compounds bound to Gbetagamma subunits with affinities from 0.1 to 60 muM and selectively modulated functional Gbetagamma-protein-protein interactions in vitro, chemotactic peptide signaling pathways in HL-60 leukocytes, and opioid receptor-dependent analgesia in vivo. These data demonstrate an approach for modulation of G protein-coupled receptor signaling that may represent an important therapeutic strategy.

Chemopreventive Strategies for Inflammation-Related Carcinogenesis: Current Status and Future Direction

PubMed Central

Kanda, Yusuke; Osaki, Mitsuhiko; Okada, Futoshi

2017-01-01

A sustained and chronically-inflamed environment is characterized by the presence of heterogeneous inflammatory cellular components, including neutrophils, macrophages, lymphocytes and fibroblasts. These infiltrated cells produce growth stimulating mediators (inflammatory cytokines and growth factors), chemotactic factors (chemokines) and genotoxic substances (reactive oxygen species and nitrogen oxide) and induce DNA damage and methylation. Therefore, chronic inflammation serves as an intrinsic niche for carcinogenesis and tumor progression. In this article, we summarize the up-to-date findings regarding definitive/possible causes and mechanisms of inflammation-related carcinogenesis derived from experimental and clinical studies. We also propose 10 strategies, as well as candidate agents for the prevention of inflammation-related carcinogenesis. PMID:28422073

Prostaglandins may play a signal-coupling role during phagocytosis in Amoeba proteus.

PubMed

Prusch, R D; Goette, S M; Haberman, P

1989-03-01

Phagocytosis in Amoeba proteus can be induced with prostaglandins (PG). In addition, arachidonic acid (the fatty acid precursor to the PG-2 series) also induces phagocytosis. The induction of phagocytosis with arachidonic acid can be partially inhibited by the cyclooxygenase inhibitor indomethacin. Phagocytosis in the amoeba can also be induced with the chemotactic peptide N-formylmethionyl-leucylphenylalanine (NFMLP). The peptide presumably induces phagocytosis by interacting with receptors on the amoeba surface, which may initiate the release of arachidonic acid from membrane lipids. NFMLP-induced phagocytosis can also be partially inhibited by indomethacin. It is suggested that PG's or biochemically related substances may play a signal-coupling role during phagocytosis in the amoeba.

Motility, Force Generation, and Energy Consumption of Unicellular Parasites.

PubMed

Hochstetter, Axel; Pfohl, Thomas

2016-07-01

Motility is a key factor for pathogenicity of unicellular parasites, enabling them to infiltrate and evade host cells, and perform several of their life-cycle events. State-of-the-art methods of motility analysis rely on a combination of optical tweezers with high-resolution microscopy and microfluidics. With this technology, propulsion forces, energies, and power generation can be determined so as to shed light on the motion mechanisms, chemotactic behavior, and specific survival strategies of unicellular parasites. With these new tools in hand, we can elucidate the mechanisms of motility and force generation of unicellular parasites, and identify ways to manipulate and eventually inhibit them. Copyright © 2016 Elsevier Ltd. All rights reserved.

Keratinocyte response to immobilized growth factors for enhanced dermal wound healing

NASA Astrophysics Data System (ADS)

Stefonek-Puccinelli, Tracy Jane

Chronic wounds cost billions of dollars per year to treat and wound care is limited to ineffective and/or expensive options. Chronic wounds are characterized by a failure to reepithelialize, as well as deficiencies in growth factors, such as epidermal growth factor (EGF) and insulin-like growth factor-1 (IGF-1), normally present during wound healing. Our system described herein begins to tackle the problems associated with designing bioactive materials for chronic wound healing applications. We show that we can induce accelerated keratinocyte migration with photo-immobilized EGF and further control migration speed through the culture of cells on different types of gradient patterns of EGF. We also successfully immobilized IGF-1 while retaining its bioactivity, and further showed it induces directed keratinocyte migration, although not as potently as immobilized EGF. Potential synergy between co-immobilized IGF-1 and EGF was also investigated, although EGF continued to dominate the cellular response, and no significant increase in cell migration was achieved via the addition of IGF-1 to the system. To further understand cellular response to our immobilized growth factors, we investigated keratinocyte signaling and function in response to changes in EGF presentation. It was found that immobilized and soluble EGF can play different, yet complementary, roles in regulating keratinocyte function. Specifically, keratinocytes responded to immobilized EGF with high EGF receptor (EGFR) activation, accompanied by low proliferation and high migratory activity. In contrast, keratinocytes treated with soluble EGF displayed a highly proliferative, rather than migratory, phenotype. We then transitioned our photo-immobilization techniques to materials that may be more suitable as a wound dressing, such as silk fibroin films. Silk fibroin is a natural fiber with many desirable qualities for a biomaterial including high strength and elasticity, biocompatibility, a beta-keratin structure which closely mimics human keratin, and ease of fabrication and modification. These silk films can also provide topographical cues via simple cast molding of any feature on the micron scale. This system allowed simultaneous presentation of topographic cues, inhibitory and/or synergistic, with our chemotactic cues. Our preliminary data suggest keratinocytes remain viable on silk fibroin films, and that these films can be patterned with immobilized EGF to induce keratinocyte migration.

NMR and SAXS characterization of the denatured state of the chemotactic protein Che Y: Implications for protein folding initiation

PubMed Central

Garcia, Pascal; Serrano, Luis; Durand, Dominique; Rico, Manuel; Bruix, Marta

2001-01-01

The denatured state of a double mutant of the chemotactic protein CheY (F14N/V83T) has been analyzed in the presence of 5 M urea, using small angle X-ray scattering (SAXS) and heteronuclear magnetic resonance. SAXS studies show that the denatured protein follows a wormlike chain model. Its backbone can be described as a chain composed of rigid elements connected by flexible links. A comparison of the contour length obtained for the chain at 5 M urea with the one expected for a fully expanded chain suggests that ∼25% of the residues are involved in residual structures. Conformational shifts of the α-protons, heteronuclear 15N-{1H} NOEs and 15N relaxation properties have been used to identify some regions in the protein that deviate from a random coil behavior. According to these NMR data, the protein can be divided into two subdomains, which largely coincide with the two folding subunits identified in a previous kinetic study of the folding of the protein. The first of these subdomains, spanning residues 1–70, is shown here to exhibit a restricted mobility as compared to the rest of the protein. Two regions, one in each subdomain, were identified as deviating from the random coil chemical shifts. Peptides corresponding to these sequences were characterized by NMR and their backbone 1H chemical shifts were compared to those in the intact protein under identical denaturing conditions. For the region located in the first subdomain, this comparison shows that the observed deviation from random coil parameters is caused by interactions with the rest of the molecule. The restricted flexibility of the first subdomain and the transient collapse detected in that subunit are consistent with the conclusions obtained by applying the protein engineering method to the characterization of the folding reaction transition state. PMID:11369848

CD147-mediated chemotaxis of CD4+CD161+ T cells may contribute to local inflammation in rheumatoid arthritis.

PubMed

Lv, Minghua; Miao, Jinlin; Zhao, Peng; Luo, Xing; Han, Qing; Wu, Zhenbiao; Zhang, Kui; Zhu, Ping

2018-01-01

CD161 is used as a surrogate marker for Th17 cells, which are implicated in the pathogenesis of rheumatoid arthritis (RA). In this study, we evaluated the percentage, clinical significance, and CD98 and CD147 expression of CD4 + CD161 + T cells. The potential role of CD147 and CD98 in cyclophilin A-induced chemotaxis of CD4 + CD161 + T cells was analyzed. Thirty-seven RA patients, 15 paired synovial fluid (SF) of RA, and 22 healthy controls were recruited. The cell populations and surface expression of CD98 and CD147 were analyzed by flow cytometry. Spearman's rank correlation coefficient and multiple linear regression were applied to calculate the correlations. Chemotaxis assay was used to investigate CD4 + CD161 + T cell migration. We found that the percentage of CD4 + CD161 + T cells and their expression of CD147 and CD98 in SF were higher than in the peripheral blood of RA patients. Percentage of SF CD4 + CD161 + T cells was positively correlated with 28-Joint Disease Activity Score (DAS28). CD147 monoclonal antibody (HAb18) attenuated the chemotactic ability of CD4 + CD161 + T cells. An increased CD4 + CD161 + T cell percentage and expression of CD147 and CD98 were shown in RA SF. Percentage of SF CD4 + CD161 + T cells can be used as a predictive marker of disease activity in RA. CD147 block significantly decreased the chemotactic index of CD4 + CD161 + cells induced by cyclophilin A (CypA). These results imply that the accumulation of CD4 + CD161 + T cells in SF and their high expression of CD147 may be associated with CypA-mediated chemotaxis and contribute to local inflammation in RA.

Use of AN Eosinophil Specific Monoclonal Antibody in Assessing Eosinophil Function.

NASA Astrophysics Data System (ADS)

Minkoff, Marjorie Sue

A monoclonal antibody to an eosinophil specific determinant is very important in assessing eosinophil function during helminthic infection. Eosinophils induced by Schistosoma mansoni infection in BALB/c mice were used to induce C57B1/6 immunocytes for production of hybridomas secreting eosinophil monoclonal antibodies. These antibodies were shown to react with an eosinophil surface epitope but not with neutrophils or macrophages as determined by ELISA, immunodiffusion, immunofluorescence, and immunoblot assay. Affinity chromatography with eosinophil chemotactic factor-sepharose consistently selected out a { rm M_ R} 67,000 protein from solubilized eosinophil membrane antigens but not from neutrophil and macrophage antigens. In vitro studies showed that the eosinophil-specific monoclonal antibodies abrogated antibody-dependent eosinophil -mediated killing of S. mansoni schistosomula using mouse, rat or human eosinophils. Neutrophil and macrophage killing activities were unaffected. The monoclonal antibodies effected complement-dependent lysis of mouse and rat eosinophils but not of human eosinophils. ECF-treated eosinophils showed enhanced killing of schistosomula which was blocked by the monoclonal antibody. Murine and human eosinophils preincubated with monoclonal antibody exhibited decreased chemotaxis to ECF at optimal chemotactic concentrations. The monoclonal antibody also blocked eosinophil binding to ECF- sepharose beads. In vivo induction of peripheral blood eosinophilia by injection of S. mansoni eggs was suppressed by injections of monoclonal antibodies 2CD13 and 2QD45 in mouse and rat experimental models. Eosinophilia induced by keyhole limpet hemocyanin- cyclophosphamide treatment was also suppressed by monoclonal antibody in both murine and rat systems. Pulmonary granulomas in mice given egg injection and monoclonal antibody were smaller and contained fewer eosinophils than those granulomas from mice given eggs only. In immuno-biochemical studies, the monoclonal antibody 2QD45 specifically immunoprecipitated the {rm M_ R} 67,000 ECF-binding protein from ^{125}{rm I}-labeled mouse, rat, and human eosinophils as assessed by SDS-PAGE and autoradiography. Two-dimensional gel electrophoresis showed that this ECF-binding protein has a lower PI point than either mouse or bovine albumin.

Effects of 17β-estradiol on the release of monocyte chemotactic protein-1 and MAPK activity in monocytes stimulated with peritoneal fluid from endometriosis patients.

PubMed

Lee, Dong-Hyung; Kim, Seung-Chul; Joo, Jong-Kil; Kim, Hwi-Gon; Na, Young-Jin; Kwak, Jong-Young; Lee, Kyu-Sup

2012-03-01

Hormones and inflammation have been implicated in the pathological process of endometriosis; therefore, we investigated the combined effects of 17β-estradiol (E2) and peritoneal fluid obtained from patients with endometriosis (ePF) or a control peritoneal fluid (cPF) obtained from patients without endometriosis on the release of monocyte chemotactic protein-1 (MCP-1) by monocytes and the role of signaling pathways. Monocytes were cultured with ePF and cPF in the presence of E2; the MCP-1 levels in the supernatants were then measured by ELISA. In addition, mitogen activated protein kinase (MAPK) activation was measured by Western blotting of phosphorylated proteins. E2 down-regulated MCP-1 release by lipopolysaccharide- or cPF-treated monocytes, but failed to suppress its release by ePF-treated monocytes. The release of MCP-1 by ePF- and cPF-treated monocytes was efficiently abrogated by p38 mitogen activated protein kinase (MAPK) inhibitors; however, the MCP-1 release by cPF-treated monocytes, but not by ePF-treated monocytes, was blocked by a MAPK kinase inhibitor. In addition, ePF and cPF induced the phosphorylation of extracellular stress regulated kinase (ERK)1/2, p38 MAPK and c-Jun N-terminal kinase (JNK). E2 decreased the phosphorylation of p38 MAPK, but not ERK1/2 in ePF-treated monocytes; however, E2 decreased the phosphorylation of p38 MAPK, ERK1/2 and JNK in cPF-treated monocytes. The ability of E2 to modulate MCP-1 production is impaired in ePF-treated monocytes, which may be related to regulation of MAPK activity. These findings suggest that the failure of E2 to suppress ePF-treated production of MCP-1 may be involved in the pathogenesis of endometriosis. © 2012 The Authors. Journal of Obstetrics and Gynaecology Research © 2012 Japan Society of Obstetrics and Gynecology.

Chemoreception of the Seagrass Posidonia Oceanica by Benthic Invertebrates is Altered by Seawater Acidification.

PubMed

Zupo, Valerio; Maibam, Chingoileima; Buia, Maria Cristina; Gambi, Maria Cristina; Patti, Francesco Paolo; Scipione, Maria Beatrice; Lorenti, Maurizio; Fink, Patrick

2015-08-01

Several plants and invertebrates interact and communicate by means of volatile organic compounds (VOCs). These compounds may play the role of infochemicals, being able to carry complex information to selected species, thus mediating inter- or intra-specific communications. Volatile organic compounds derived from the wounding of marine diatoms, for example, carry information for several benthic and planktonic invertebrates. Although the ecological importance of VOCs has been demonstrated, both in terrestrial plants and in marine microalgae, their role as infochemicals has not been demonstrated in seagrasses. In addition, benthic communities, even the most complex and resilient, as those associated to seagrass meadows, are affected by ocean acidification at various levels. Therefore, the acidification of oceans could produce interference in the way seagrass-associated invertebrates recognize and choose their specific environments. We simulated the wounding of Posidonia oceanica leaves collected at two sites (a control site at normal pH, and a naturally acidified site) off the Island of Ischia (Gulf of Naples, Italy). We extracted the VOCs and tested a set of 13 species of associated invertebrates for their specific chemotactic responses in order to determine if: a) seagrasses produce VOCs playing the role of infochemicals, and b) their effects can be altered by seawater pH. Our results indicate that several invertebrates recognize the odor of wounded P. oceanica leaves, especially those strictly associated to the leaf stratum of the seagrass. Their chemotactic reactions may be modulated by the seawater pH, thus impairing the chemical communications in seagrass-associated communities in acidified conditions. In fact, 54% of the tested species exhibited a changed behavioral response in acidified waters (pH 7.7). Furthermore, the differences observed in the abundance of invertebrates, in natural vs. acidified field conditions, are in agreement with these behavioral changes. Therefore, leaf-produced infochemicals may influence the structure of P. oceanica epifaunal communities, and their effects can be regulated by seawater acidification.

Beneficial effects of the naturally occurring flavonoid silibinin on the prostate cancer microenvironment: role of monocyte chemotactic protein-1 and immune cell recruitment.

PubMed

Ting, Harold; Deep, Gagan; Kumar, Sushil; Jain, Anil K; Agarwal, Chapla; Agarwal, Rajesh

2016-06-01

Tumor microenvironment plays an essential role in prostate carcinogenesis and offers novel opportunities to prevent and treat prostate cancer (PCA). Here, we investigated the ability of cancer-associated fibroblasts (CAFs) to promote PCA progression, and silibinin efficacy to target this response. We collected conditioned media from CAFs treated with vehicle or silibinin, and labeled as control conditioned media (CCM) or silibinin-treatment conditioned media (SBCM), respectively. Next, we characterized the effect of CCM and SBCM treatment in several PCA cell lines (RWPE-1, WPE-1 NA-22, WPE-1 NB-14 and PC3). Result showed that compared with SBCM, CCM significantly reduces E-cadherin expression and increases invasiveness and clonogenicity in PCA cells. Further molecular studies identified monocyte chemotactic protein-1 (MCP-1) as the key component of CCM that promotes PCA invasiveness, whereas silibinin treatment strongly reduced MCP-1 expression in CAFs by inhibiting the DNA-binding activity of MCP-1 transcriptional regulators-nuclear factor-kappaB and AP-1. In vivo, silibinin feeding (200mg/kg body weight) strongly reduced TRAMPC1 allografts growth (by 68%) in syngeneic C57Bl/6 mice. TRAMPC1 tumor analysis showed that silibinin reduced MCP-1 and CAFs' biomarkers (fibroblast activation protein, α-smooth muscle actin, transforming growth factor beta 2, vimentin etc.) and significantly modulated the recruitment of immune cells in the tumor microenvironment. Similar inhibitory effects of silibinin on MCP-1 and immune cells recruitment were also observed in TRAMP PCA tissues with reported silibinin efficacy. Overall, our data suggest that silibinin can target CAF-mediated invasiveness in PCA by inhibiting MCP-1 secretion. This, in turn, was associated with a reduction in immune cell recruitment in vivo along with a marked reduction in tumor growth. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Beneficial effects of the naturally occurring flavonoid silibinin on the prostate cancer microenvironment: role of monocyte chemotactic protein-1 and immune cell recruitment

PubMed Central

Ting, Harold; Deep, Gagan; Kumar, Sushil; Jain, Anil K.; Agarwal, Chapla; Agarwal, Rajesh

2016-01-01

Tumor microenvironment plays an essential role in prostate carcinogenesis and offers novel opportunities to prevent and treat prostate cancer (PCA). Here, we investigated the ability of cancer-associated fibroblasts (CAFs) to promote PCA progression, and silibinin efficacy to target this response. We collected conditioned media from CAFs treated with vehicle or silibinin, and labeled as control conditioned media (CCM) or silibinin-treatment conditioned media (SBCM), respectively. Next, we characterized the effect of CCM and SBCM treatment in several PCA cell lines (RWPE-1, WPE-1 NA-22, WPE-1 NB-14 and PC3). Result showed that compared with SBCM, CCM significantly reduces E-cadherin expression and increases invasiveness and clonogenicity in PCA cells. Further molecular studies identified monocyte chemotactic protein-1 (MCP-1) as the key component of CCM that promotes PCA invasiveness, whereas silibinin treatment strongly reduced MCP-1 expression in CAFs by inhibiting the DNA-binding activity of MCP-1 transcriptional regulators—nuclear factor-kappaB and AP-1. In vivo, silibinin feeding (200mg/kg body weight) strongly reduced TRAMPC1 allografts growth (by 68%) in syngeneic C57Bl/6 mice. TRAMPC1 tumor analysis showed that silibinin reduced MCP-1 and CAFs’ biomarkers (fibroblast activation protein, α-smooth muscle actin, transforming growth factor beta 2, vimentin etc.) and significantly modulated the recruitment of immune cells in the tumor microenvironment. Similar inhibitory effects of silibinin on MCP-1 and immune cells recruitment were also observed in TRAMP PCA tissues with reported silibinin efficacy. Overall, our data suggest that silibinin can target CAF-mediated invasiveness in PCA by inhibiting MCP-1 secretion. This, in turn, was associated with a reduction in immune cell recruitment in vivo along with a marked reduction in tumor growth. PMID:27207648

The effect of short term treatment with probiotic VSL#3 on various clinical and biochemical parameters in patients with liver cirrhosis.

PubMed

Marlicz, W; Wunsch, E; Mydlowska, M; Milkiewicz, M; Serwin, K; Mularczyk, M; Milkiewicz, P; Raszeja-Wyszomirska, J

2016-12-01

The evidence is mounting that alterations of innate immunity and gut microbiota contribute to chronic liver disease and its complications. Modulation of intestinal microbiota is an emerging therapeutic strategy in hepatology. Probiotics through modulation of intestinal milieu have the potential to affect the course of liver disease. The data concerning the influence of probiotics on various plasma molecules and compounds involved in the pathogenesis of hyperdynamic circulatory state in liver cirrhosis is still not confluent and require further evaluation. In our study twenty patients with compensated and decompensated liver cirrhosis and ten healthy controls received probiotic VSL#3 daily for 28 days. Plasma levels of interleukin 6 (IL-6), vascular endothelial growth factor (VEGF), plasminogen activator inhibitor (PAI), macrophage inflammatory protein 3/α (MIP-3 α/CCL20), monocyte chemotactic protein-1α (MCP-1/CCL2), human myeloperoxidase (MPO), nitric oxide (NO), prostaglandins, thromboxane (TXB 2 ) and big-endothelin were measured at baseline, day 14 and 28 of probiotic administration. The incidence of hepatic encephalopathy was assessed with critical flicker frequency. Changes in clinical, biochemical and microbiological parameters were evaluated. The stage of liver cirrhosis correlated with an increase in plasma levels of pro-inflammatory cytokines (IL-6) and chemotactic chemokines involved in immune cell trafficking (MIP-3α/CCL20). Probiotic administration in patients with liver cirrhosis led to modulation of plasma levels of several molecules and compounds measured (MIP-3α/CCL20, NO, big-endothelin, TXB 2 and MPO). The grade of encephalopathy during the course of probiotic supplementation remained unaffected in both groups of patients. VSL#3 treatment was well tolerated and safe in patients with liver disease. In patients with compensated and decompensated liver cirrhosis, VSL#3 manipulates selected plasma molecules and compounds involved in hyperdynamic circulatory dysfunction. Short term VSL#3 administration affects several clinical and biochemical parameters commonly altered in liver cirrhosis.

CXCL4L1 inhibits angiogenesis and induces undirected endothelial cell migration without affecting endothelial cell proliferation and monocyte recruitment.

PubMed

Sarabi, A; Kramp, B K; Drechsler, M; Hackeng, T M; Soehnlein, O; Weber, C; Koenen, R R; Von Hundelshausen, P

2011-01-01

The non-allelic variant of CXCL4/PF4, CXCL4L1/PF4alt, differs from CXCL4 in three amino acids of the C-terminal α-helix and has been characterized as a potent anti-angiogenic regulator. Although CXCL4 structurally belongs to the chemokine family, it does not behave like a 'classical' chemokine, lacking significant chemotactic properties. Specific hallmarks are its angiostatic, anti-proliferative activities, and proinflammatory functions, which can be conferred by heteromer-formation with CCL5/RANTES enhancing monocyte recruitment. Here we show that tube formation of endothelial cells was inhibited by CXCL4L1 and CXCL4, while only CXCL4L1 triggered chemokinesis of endothelial cells. The chemotactic response towards VEGF and bFGF was attenuated by both variants and CXCL4L1-induced chemokinesis was blocked by bFGF or VEGF. Endothelial cell proliferation was inhibited by CXCL4 (IC(50) 6.9 μg mL(-1)) but not by CXCL4L1, while both chemokines bound directly to VEGF and bFGF. Moreover, CXCL4 enhanced CCL5-induced monocyte arrest in flow adhesion experiments and monocyte recruitment into the mouse peritoneal cavity in vivo, whereas CXCL4L1 had no effect. CXCL4L1 revealed lower affinity to CCL5 than CXCL4, as quantified by isothermal fluorescence titration. As evidenced by the reduction of the activated partial thromboplastin time, CXCL4L1 showed a tendency towards less heparin-neutralizing activity than CXCL4 (IC(50) 2.45 vs 0.98 μg mL(-1)).  CXCL4L1 may act angiostatically by causing random endothelial cell locomotion, disturbing directed migration towards angiogenic chemokines, serving as a homeostatic chemokine with a moderate structural distinction yet different functional profile from CXCL4. © 2010 International Society on Thrombosis and Haemostasis.

Temporal cascade of inflammatory cytokines and cell-type populations in monocyte chemotactic protein-1 (MCP-1)-mediated aneurysm healing.

PubMed

Hoh, Brian L; Fazal, Hanain Z; Hourani, Siham; Li, Mengchen; Lin, Li; Hosaka, Koji

2018-03-01

We have previously shown that monocyte chemotactic protein-1 (MCP-1) promotes aneurysm healing. To determine the temporal cascade and durability of aneurysm healing. Murine carotid aneurysms were treated with MCP-1-releasing or poly(lactic-co-glycolic) acid (PLGA)-only coils. Aneurysm healing was assessed by quantitative measurements of intraluminal tissue ingrowth on 5 μm sections by blinded observers. Aneurysm healing occurred in stages characteristic of normal wound healing. The 1st stage (day 3) was characterized by a spike in neutrophils and T cells. The 2nd stage (week 1) was characterized by an influx of macrophages and CD45+ cells significantly greater with MCP-1 than with PLGA (p<0.05). The third stage (week 2-3) was characterized by proliferation of smooth muscle cells and fibroblasts (greater with MCP-1 than with PLGA, p<0.05). The fourth stage (3-6 months) was characterized by leveling off of smooth muscle cells and fibroblasts. M1 macrophages were greater at week 1, whereas M2 macrophages were greater at weeks 2 and 3 with MCP-1 than with PLGA. Interleukin 6 was present early and increased through week 2 (p<0.05 compared with PLGA) then decreased and leveled off through 6 months. Tumour necrosis factor α was present early and remained constant through 6 months. MCP-1 and PLGA treatment had similar rates of tissue ingrowth at early time points, but MCP-1 had a significantly greater tissue ingrowth at week 3 (p<0.05), which persisted for 6 months. The sequential cascade is consistent with an inflammatory model of injury, repair, and remodeling. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

The Monocyte Chemotactic Protein-1 — Interleukin-6 — Osteopontin Pathway of Intra-Aneurysmal Tissue Healing

PubMed Central

Hosaka, Koji; Rojas, Kelley; Fazal, Hanain Z; Schneider, Matheus B; Shores, Jorma; Federico, Vincent; McCord, Matthew; Lin, Li; Hoh, Brian

2017-01-01

Background and Purpose We have previously demonstrated that the local delivery of monocyte chemotactic protein-1 (MCP-1) via a MCP-1-releasing poly(lactic-co-glycolic acid) (PLGA) -coated coil promotes intra-aneurysmal tissue healing. In this study, we demonstrate that interleukin-6 (IL-6) and osteopontin (OPN) are downstream mediators in the MCP-1-mediated aneurysm healing pathway. Methods Murine carotid aneurysms were created in C57BL/6 mice. Drug-releasing coils (MCP-1, IL-6 and OPN) and control PLGA coils were created and then implanted into the aneurysms in order to evaluate their intra-aneurysmal healing capacity. In order to investigate the downstream mediators for aneurysm healing, blocking antibodies for IL-6 receptor and OPN were given to the mice implanted with the MCP-1-releasing coils. A histological analysis of both murine and human aneurysms was utilized to cross-validate the data. Results We observed increased expression of IL-6 in MCP-1-coil treated aneurysms and not in control-PLGA-only treated aneurysms. MCP-1-mediated intra-aneurysmal healing is inhibited in mice given blocking antibody to IL-6 receptor. MCP-1-mediated intra-aneurysmal healing is also inhibited by blocking antibody to OPN. The role of IL-6 in intra-aneurysmal healing is in recruiting of endothelial cells and fibroblasts. Local delivery of OPN to murine carotid aneurysms via OPN-releasing coil significantly promotes intra-aneurysmal healing, but IL-6-releasing coil does not, suggesting that IL-6 cannot promote aneurysm healing independent of MCP-1. In the MCP-1-mediated aneurysm healing, OPN expression is dependent on IL-6; inhibition of IL-6 receptor significantly inhibits OPN expression in MCP-1-mediated aneurysm healing. Conclusions Our findings suggest that IL-6 and OPN are key downstream mediators of MCP-1-mediated intra-aneurysmal healing. PMID:28292871

Local Delivery Is Critical for Monocyte Chemotactic Protein-1 Mediated Site-Specific Murine Aneurysm Healing.

PubMed

Hourani, Siham; Motwani, Kartik; Wajima, Daisuke; Fazal, Hanain; Jones, Chad H; Doré, Sylvain; Hosaka, Koji; Hoh, Brian L

2018-01-01

Local delivery of monocyte chemotactic protein-1 (MCP-1/CCL2) via our drug-eluting coil has been shown to promote intrasaccular aneurysm healing via an inflammatory pathway. In this study, we validate the importance of local MCP-1 in murine aneurysm healing. Whether systemic, rather than local, delivery of MCP-1 can direct site-specific aneurysm healing has significant translational implications. If systemic MCP-1 is effective, then MCP-1 could be administered as a pill rather than by endovascular procedure. Furthermore, we confirm that MCP-1 is the primary effector in our MCP-1 eluting coil-mediated murine aneurysm healing model. We compare aneurysm healing with repeated intraperitoneal MCP-1 versus vehicle injection, in animals with control poly(lactic-co-glycolic) acid (PLGA)-coated coils. We demonstrate elimination of the MCP-1-associated tissue-healing response by knockout of MCP-1 or CCR2 (MCP-1 receptor) and by selectively inhibiting MCP-1 or CCR2. Using immunofluorescent probing, we explore the cell populations found in healed aneurysm tissue following each intervention. Systemically administered MCP-1 with PLGA coil control does not produce comparable aneurysm healing, as seen with MCP-1 eluting coils. MCP-1-directed aneurysm healing is eliminated by selective inhibition of MCP-1 or CCR2 and in MCP-1-deficient or CCR2-deficient mice. No difference was detected in M2 macrophage and myofibroblast/smooth muscle cell staining with systemic MCP-1 versus vehicle in aneurysm wall, but a significant increase in these cell types was observed with MCP-1 eluting coil implant and attenuated by MCP-1/CCR2 blockade or deficiency. We show that systemic MCP-1 concurrent with PLGA-coated platinum coil implant is not sufficient to produce site-specific aneurysm healing. MCP-1 is a critical, not merely complementary, actor in the aneurysm healing pathway.

Desloratadine citrate disodium injection, a potent histamine H(1) receptor antagonist, inhibits chemokine production in ovalbumin-induced allergic rhinitis guinea pig model and histamine-induced human nasal epithelial cells via inhibiting the ERK1/2 and NF-kappa B signal cascades.

PubMed

Chen, Meiling; Xu, Shuhong; Zhou, Peipei; He, Guangwei; Jie, Qiong; Wu, Yulin

2015-11-15

Chemokines have chemotactic properties on leukocyte subsets whose modulation plays a pivotal role in allergic inflammatory processes. Our present study was designed to investigate the anti-allergic and anti-inflammatory properties of desloratadine citrate disodium injection (DLC) and elucidate the molecular mechanisms of its anti-inflammatory properties. The anti-allergic effects of DLC were evaluated based on allergic symptoms, serological marker production and histological changes of the nasal mucosa in guinea pigs model of allergic rhinitis. The anti-inflammatory properties and molecular mechanisms of DLC were explored by studying the regulation of a set of chemokines and extracellular signal-regulated kinase (ERK)1/2 and nuclear factor-kappa B (NF-κB) pathways, after DLC treatment in guinea pigs model of allergic rhinitis in vivo and histamine-activated human nasal epithelial cells (HNECs) in vitro. In vivo model in guinea pigs, DLC alleviated the rhinitis symptoms, inhibited inflammatory cells infiltration in nasal lavage fluid (NLF) and histamine, monocyte chemotactic protein (MCP)-1, regulated on activation normal T cell expressed, and presumably secreted (RANTEs) and interleukin (IL)-8 release in sera and P-ERK1/2 and NF-κB activation in nasal mucosa. In vitro, DLC markedly inhibited histamine-induced production of MCP-1, RANTEs and IL-8 and suppressed c-Raf, mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK) and ERK1/2 activation in HNECs. These results provide evidence that DLC possesses potent anti-allergic and anti-inflammatory properties. The mechanism of action underlying DLC in allergic inflammation appears to be inhibition of the phosphorylation of ERK1/2, in addition to blocking of the NF-κB pathway. Copyright © 2015 Elsevier B.V. All rights reserved.

Chemotactic peptide fMetLeuPhe induces translocation of the TRPV2 channel in macrophages.

PubMed

Nagasawa, Masahiro; Nakagawa, Yuko; Tanaka, Shigeyasu; Kojima, Itaru

2007-03-01

The present study was conducted to characterize the regulation and function of TRPV2 in macrophages. Among six members of the TRPV family channels, only the expression of TRPV2 was detected in macrophages. We then determined localization of TRPV2 using TtT/M87 macrophages transfected with TRPV2-EGFP. In serum-free condition, most of the TRPV2 signal was located in the cytoplasm and colocalized with the endoplasmic reticulum marker. Treatment with serum induced translocation of some of the TRPV2-EGFP to the plasma membrane. Serum-induced translocation was blocked by transfection of short-form TRPV2 (s-TRPV2) lacking a pore-forming region and the sixth transmembrane domain. Addition of a chemotactic peptide formyl Met-Leu-Phe (fMLP) also induced translocation of TRPV2-EGFP to the plasma membrane. The fMLP-induced translocation was blocked by an inhibitor of PI 3-kinase, LY294002, and pertussis toxin. Whole-cell patch clamp analysis showed a Cs+ current in the TtT/M87 cell, which was blocked by an addition of ruthenium red and transfection of either s-TRPV2 or siRNA for TRPV2. fMLP increased the Cs+ current. fMLP induced a rapid and sustained elevation of cytoplasmic Ca2+ ([Ca2+]C), the sustained phase of which was abolished by removal of extracellular calcium. The sustained elevation of [Ca2+]C was also blocked by ruthenium red, and transfection of either s-TRPV2 or siRNA. Finally, fMLP-induced migration of macrophage was blocked by ruthenium red or transfection of s-TRPV2. These results suggest that fMLP induces translocation of TRPV2 from intracellular compartment to the plasma membrane, and this translocation is critical for fMLP-induced calcium entry. Copyright 2006 Wiley-Liss, Inc.

μ-'Diving suit' for liquid-phase high-Q resonant detection.

PubMed

Yu, Haitao; Chen, Ying; Xu, Pengcheng; Xu, Tiegang; Bao, Yuyang; Li, Xinxin

2016-03-07

A resonant cantilever sensor is, for the first time, dressed in a water-proof 'diving suit' for real-time bio/chemical detection in liquid. The μ-'diving suit' technology can effectively avoid not only unsustainable resonance due to heavy liquid-damping, but also inevitable nonspecific adsorption on the cantilever body. Such a novel technology ensures long-time high-Q resonance of the cantilever in solution environment for real-time trace-concentration bio/chemical detection and analysis. After the formation of the integrated resonant micro-cantilever, a patterned photoresist and hydrophobic parylene thin-film are sequentially formed on top of the cantilever as sacrificial layer and water-proof coat, respectively. After sacrificial-layer release, an air gap is formed between the parylene coat and the cantilever to protect the resonant cantilever from heavy liquid damping effect. Only a small sensing-pool area, located at the cantilever free-end and locally coated with specific sensing-material, is exposed to the liquid analyte for gravimetric detection. The specifically adsorbed analyte mass can be real-time detected by recording the frequency-shift signal. In order to secure vibration movement of the cantilever and, simultaneously, reject liquid leakage from the sensing-pool region, a hydrophobic parylene made narrow slit structure is designed surrounding the sensing-pool. The anti-leakage effect of the narrow slit and damping limited resonance Q-factor are modelled and optimally designed. Integrated with electro-thermal resonance excitation and piezoresistive frequency readout, the cantilever is embedded in a micro-fluidic chip to form a lab-chip micro-system for liquid-phase bio/chemical detection. Experimental results show the Q-factor of 23 in water and longer than 20 hours liquid-phase continuous working time. Loaded with two kinds of sensing-materials at the sensing-pools, two types of sensing chips successfully show real-time liquid-phase detection to ppb-level organophosphorous pesticide of acephate and E.coli DH5α in PBS, respectively. The proposed method fundamentally solves the long-standing problem of being unable to operate a resonant micro-sensor in liquid well.

Differential Targeting of Gβγ-Subunit Signaling with Small Molecules

NASA Astrophysics Data System (ADS)

Bonacci, Tabetha M.; Mathews, Jennifer L.; Yuan, Chujun; Lehmann, David M.; Malik, Sundeep; Wu, Dianqing; Font, Jose L.; Bidlack, Jean M.; Smrcka, Alan V.

2006-04-01

G protein βγ subunits have potential as a target for therapeutic treatment of a number of diseases. We performed virtual docking of a small-molecule library to a site on Gβγ subunits that mediates protein interactions. We hypothesized that differential targeting of this surface could allow for selective modulation of Gβγ subunit functions. Several compounds bound to Gβγ subunits with affinities from 0.1 to 60 μM and selectively modulated functional Gβγ-protein-protein interactions in vitro, chemotactic peptide signaling pathways in HL-60 leukocytes, and opioid receptor-dependent analgesia in vivo. These data demonstrate an approach for modulation of G protein-coupled receptor signaling that may represent an important therapeutic strategy.

Noisy Oscillations in the Actin Cytoskeleton of Chemotactic Amoeba.

PubMed

Negrete, Jose; Pumir, Alain; Hsu, Hsin-Fang; Westendorf, Christian; Tarantola, Marco; Beta, Carsten; Bodenschatz, Eberhard

2016-09-30

Biological systems with their complex biochemical networks are known to be intrinsically noisy. Here we investigate the dynamics of actin polymerization of amoeboid cells, which are close to the onset of oscillations. We show that the large phenotypic variability in the polymerization dynamics can be accurately captured by a generic nonlinear oscillator model in the presence of noise. We determine the relative role of the noise with a single dimensionless, experimentally accessible parameter, thus providing a quantitative description of the variability in a population of cells. Our approach, which rests on a generic description of a system close to a Hopf bifurcation and includes the effect of noise, can characterize the dynamics of a large class of noisy systems close to an oscillatory instability.

Fine Tuning Cell Migration by a Disintegrin and Metalloproteinases

PubMed Central

Theodorou, K.

2017-01-01

Cell migration is an instrumental process involved in organ development, tissue homeostasis, and various physiological processes and also in numerous pathologies. Both basic cell migration and migration towards chemotactic stimulus consist of changes in cell polarity and cytoskeletal rearrangement, cell detachment from, invasion through, and reattachment to their neighboring cells, and numerous interactions with the extracellular matrix. The different steps of immune cell, tissue cell, or cancer cell migration are tightly coordinated in time and place by growth factors, cytokines/chemokines, adhesion molecules, and receptors for these ligands. This review describes how a disintegrin and metalloproteinases interfere with several steps of cell migration, either by proteolytic cleavage of such molecules or by functions independent of proteolytic activity. PMID:28260841

A case report of spinal dural arteriovenous fistula: origins, determinants, and consequences of abnormal vascular malformations.

PubMed

Zakhary, Sherry M; Hoehmann, Christopher L; Cuoco, Joshua A; Hitscherich, Kyle; Alam, Hamid; Torres, German

2017-06-01

A spinal dural arteriovenous fistula is an abnormally layered connection between radicular arteries and venous plexus of the spinal cord. This vascular condition is relatively rare with an incidence of 5-10 cases per million in the general population. Diagnosis of spinal dural arteriovenous fistula is differentiated by contrast-enhanced magnetic resonance angiography or structural magnetic resonance imaging, but a definitive diagnosis requires spinal angiography methods. Here, we report a case of a 67-year-old female with a spinal dural arteriovenous fistula, provide a pertinent clinical history to the case nosology, and discuss the biology of adhesive proteins, chemotactic molecules, and transcription factors that modify the behavior of the vasculature to possibly cause sensorimotor deficits.

Spiral and never-settling patterns in active systems

NASA Astrophysics Data System (ADS)

Yang, X.; Marenduzzo, D.; Marchetti, M. C.

2014-01-01

We present a combined numerical and analytical study of pattern formation in an active system where particles align, possess a density-dependent motility, and are subject to a logistic reaction. The model can describe suspensions of reproducing bacteria, as well as polymerizing actomyosin gels in vitro or in vivo. In the disordered phase, we find that motility suppression and growth compete to yield stable or blinking patterns, which, when dense enough, acquire internal orientational ordering to give asters or spirals. We predict these may be observed within chemotactic aggregates in bacterial fluids. In the ordered phase, the reaction term leads to previously unobserved never-settling patterns which can provide a simple framework to understand the formation of motile and spiral patterns in intracellular actin systems.

'Extremotaxis': computing with a bacterial-inspired algorithm.

PubMed

Nicolau, Dan V; Burrage, Kevin; Nicolau, Dan V; Maini, Philip K

2008-01-01

We present a general-purpose optimization algorithm inspired by "run-and-tumble", the biased random walk chemotactic swimming strategy used by the bacterium Escherichia coli to locate regions of high nutrient concentration The method uses particles (corresponding to bacteria) that swim through the variable space (corresponding to the attractant concentration profile). By constantly performing temporal comparisons, the particles drift towards the minimum or maximum of the function of interest. We illustrate the use of our method with four examples. We also present a discrete version of the algorithm. The new algorithm is expected to be useful in combinatorial optimization problems involving many variables, where the functional landscape is apparently stochastic and has local minima, but preserves some derivative structure at intermediate scales.

Monocyte function in infectious mononucleosis: evidence for a reversible cellular defect.

PubMed

Britton, S

1976-10-01

Migration of blood monocytes from patients with acute infectious mononucleosis and from normal controls was measured against chemotactic factors in serum. Moncytes from patients with acute infectious mononucleosis showed decreased migration as compared with that of control monocytes. However, serum from patients with infectious mononucleosis contained normal or above normal amounts of chemotaxins for monocytes. The migratory defect of monocytes from patients with infectious mononucleosis was reversible within three months after the onset of diesease. The cause of this monocyte migration defect in infectious mononucleosis is though to be an in vivo blockade of receptors on monocytes for chemotaxins, and it is speculated that this defect can partially explain the explain the ablated delayed-hypersensitivity skin reactions in this disease.

CD147 is a signaling receptor for cyclophilin B.

PubMed

Yurchenko, V; O'Connor, M; Dai, W W; Guo, H; Toole, B; Sherry, B; Bukrinsky, M

2001-11-09

Cyclophilins A and B (CyPA and CyPB) are cyclosporin A binding proteins that can be secreted in response to inflammatory stimuli. We recently identified CD147 as a cell-surface receptor for CyPA and demonstrated that CD147 is an essential component in the CyPA-initiated signaling cascade that culminates in ERK activation and chemotaxis. Here we demonstrate that CD147 also serves as a receptor for CyPB. CyPB induced Ca(2+) flux and chemotaxis of CD147-transfected, but not control, CHO cells, and the chemotactic response of primary human neutrophils to CyPB was blocked by antibodies to CD147. These results suggest that CD147 serves as a receptor for extracellular cyclophilins. Copyright 2001 Academic Press.

Blockade by fenspiride of endotoxin-induced neutrophil migration in the rat.

PubMed

Cunha, F Q; Boukili, M A; da Motta, J I; Vargaftig, B B; Ferreira, S H

1993-07-06

Fenspiride, an antiinflammatory drug with low anti-cyclooxygenase activity, administered orally at 60-200 mg/kg inhibited neutrophil migration into peritoneal and air pouches cavities as well as exudation into peritoneal cavities induced by endotoxin but not induced by carrageenin. Up to 100 microM, fenspiride failed to inhibit the in vitro release of a neutrophil chemotactic activity by endotoxin-stimulated macrophages and the in vivo migration into the peritoneal cavities induced by the supernatant of those macrophages. The release of tumour necrosis factor by stimulated macrophages was inhibited by fenspiride in a dose-dependent manner. These results suggest that the antiinflammatory effects of fenspiride are associated with the inhibition of the tumour necrosis factor release by resident macrophages.