These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

The Lectin Pathway of Complement and Rheumatic Heart Disease  

PubMed Central

The innate immune system is the first line of host defense against infection and is comprised of humoral and cellular mechanisms that recognize potential pathogens within minutes or hours of entry. The effector components of innate immunity include epithelial barriers, phagocytes, and natural killer cells, as well as cytokines and the complement system. Complement plays an important role in the immediate response against microorganisms, including Streptococcus sp. The lectin pathway is one of three pathways by which the complement system can be activated. This pathway is initiated by the binding of mannose-binding lectin (MBL), collectin 11 (CL-K1), and ficolins (Ficolin-1, Ficolin-2, and Ficolin-3) to microbial surface oligosaccharides and acetylated residues, respectively. Upon binding to target molecules, MBL, CL-K1, and ficolins form complexes with MBL-associated serine proteases 1 and 2 (MASP-1 and MASP-2), which cleave C4 and C2 forming the C3 convertase (C4b2a). Subsequent activation of complement cascade leads to opsonization, phagocytosis, and lysis of target microorganisms through the formation of the membrane-attack complex. In addition, activation of complement may induce several inflammatory effects, such as expression of adhesion molecules, chemotaxis and activation of leukocytes, release of reactive oxygen species, and secretion of cytokines and chemokines. In this chapter, we review the general aspects of the structure, function, and genetic polymorphism of lectin-pathway components and discuss most recent understanding on the role of the lectin pathway in the predisposition and clinical progression of Rheumatic Fever. PMID:25654073

Beltrame, Marcia Holsbach; Catarino, Sandra Jeremias; Goeldner, Isabela; Boldt, Angelica Beate Winter; de Messias-Reason, Iara José

2014-01-01

2

The lectin pathway of complement and rheumatic heart disease.  

PubMed

The innate immune system is the first line of host defense against infection and is comprised of humoral and cellular mechanisms that recognize potential pathogens within minutes or hours of entry. The effector components of innate immunity include epithelial barriers, phagocytes, and natural killer cells, as well as cytokines and the complement system. Complement plays an important role in the immediate response against microorganisms, including Streptococcus sp. The lectin pathway is one of three pathways by which the complement system can be activated. This pathway is initiated by the binding of mannose-binding lectin (MBL), collectin 11 (CL-K1), and ficolins (Ficolin-1, Ficolin-2, and Ficolin-3) to microbial surface oligosaccharides and acetylated residues, respectively. Upon binding to target molecules, MBL, CL-K1, and ficolins form complexes with MBL-associated serine proteases 1 and 2 (MASP-1 and MASP-2), which cleave C4 and C2 forming the C3 convertase (C4b2a). Subsequent activation of complement cascade leads to opsonization, phagocytosis, and lysis of target microorganisms through the formation of the membrane-attack complex. In addition, activation of complement may induce several inflammatory effects, such as expression of adhesion molecules, chemotaxis and activation of leukocytes, release of reactive oxygen species, and secretion of cytokines and chemokines. In this chapter, we review the general aspects of the structure, function, and genetic polymorphism of lectin-pathway components and discuss most recent understanding on the role of the lectin pathway in the predisposition and clinical progression of Rheumatic Fever. PMID:25654073

Beltrame, Marcia Holsbach; Catarino, Sandra Jeremias; Goeldner, Isabela; Boldt, Angelica Beate Winter; de Messias-Reason, Iara José

2014-01-01

3

Mechanisms of complement lectin pathway activation and resistance by trypanosomatid parasites.  

PubMed

Studies in the past decade have demonstrated a crucial role for the complement lectin pathway in host defence against protozoan microbes. Recognition of pathogen surface molecules by mannan-binding lectin and ficolins revealed new mechanisms of innate immune defence and a diversity of parasite strategies of immune evasion. In the present review, we will discuss the current knowledge of: (1) the molecular mechanism of lectin pathway activation by trypanosomes; (2) the mechanisms of complement evasion by trypanosomes; and (3) host genetic deficiencies of complement lectin pathway factors that contribute to infection susceptibility and disease progression. This review will focus on trypanosomatids, the parasites that cause Chagas disease, leishmaniasis and sleeping sickness (African trypanosomiasis). PMID:23063472

Cestari, Igor; Evans-Osses, Ingrid; Schlapbach, Luregn J; de Messias-Reason, Iara; Ramirez, Marcel I

2013-04-01

4

Scabies mite inactive serine proteases are potent inhibitors of the human complement lectin pathway.  

PubMed

Scabies is an infectious skin disease caused by the mite Sarcoptes scabiei and has been classified as one of the six most prevalent epidermal parasitic skin diseases infecting populations living in poverty by the World Health Organisation. The role of the complement system, a pivotal component of human innate immunity, as an important defence against invading pathogens has been well documented and many parasites have an arsenal of anti-complement defences. We previously reported on a family of scabies mite proteolytically inactive serine protease paralogues (SMIPP-Ss) thought to be implicated in host defence evasion. We have since shown that two family members, SMIPP-S D1 and I1 have the ability to bind the human complement components C1q, mannose binding lectin (MBL) and properdin and are capable of inhibiting all three human complement pathways. This investigation focused on inhibition of the lectin pathway of complement activation as it is likely to be the primary pathway affecting scabies mites. Activation of the lectin pathway relies on the activation of MBL, and as SMIPP-S D1 and I1 have previously been shown to bind MBL, the nature of this interaction was examined using binding and mutagenesis studies. SMIPP-S D1 bound MBL in complex with MBL-associated serine proteases (MASPs) and released the MASP-2 enzyme from the complex. SMIPP-S I1 was also able to bind MBL in complex with MASPs, but MASP-1 and MASP-2 remained in the complex. Despite these differences in mechanism, both molecules inhibited activation of complement components downstream of MBL. Mutagenesis studies revealed that both SMIPP-Ss used an alternative site of the molecule from the residual active site region to inhibit the lectin pathway. We propose that SMIPP-Ss are potent lectin pathway inhibitors and that this mechanism represents an important tool in the immune evasion repertoire of the parasitic mite and a potential target for therapeutics. PMID:24854034

Reynolds, Simone L; Pike, Robert N; Mika, Angela; Blom, Anna M; Hofmann, Andreas; Wijeyewickrema, Lakshmi C; Kemp, Dave; Fischer, Katja

2014-05-01

5

Paths reunited: initiation of the classical and lectin pathways of complement activation  

PubMed Central

Since its isolation almost fifty years ago, considerable progress has been made towards understanding the structural organisation and mode of action of C1, the initiating complex of the classical pathway of complement activation. Nevertheless, knowledge is still incomplete, especially with regard to the interactions between subcomponents, C1q, C1r and C1s, that trigger activation. Recent studies have provided new insights into these interactions, and have revealed unexpected parallels with initiating complexes of the lectin pathway of complement: MBL-MASP and ficolin-MASP. Here, we develop and expand these concepts and delineate their implications towards the key aspects of complement activation via the classical and lectin pathways. PMID:19783065

Wallis, Russell; Mitchell, Daniel A.; Schmid, Ralf; Schwaeble, Wilhelm W.; Keeble, Anthony H.

2010-01-01

6

Lectin complement pathway gene profile of the donor and recipient does not influence graft outcome after kidney transplantation.  

PubMed

In kidney transplantation, complement activation was found to be induced by donor brain death, renal ischemia-reperfusion injury and allograft rejection. There are three known pathways of complement activation: the classical, lectin and the alternative pathway. The lectin complement pathway can be activated upon pattern recognition by mannan binding lectin (MBL) or ficolins (FCN). Single nucleotide polymorphisms (SNPs) in the genes encoding the lectin pathway proteins determine their functional activity and serum levels. The aim of this study was to investigate the role of the lectin gene profile of the donor and recipient on post-transplant outcome. A total of 12 functional SNPs in the MBL2, FCN2 and MBL-associated serine proteases 2 (MASP2) genes of 1271 donor-recipient pairs were determined. Lectin genotypic variants were analyzed for association with primary non-function (PNF), delayed graft function (DGF), biopsy proven acute rejection, death-censored graft survival and patient survival. Multivariate analyses found no association of donor and recipient MBL2 and MASP2 genotype with allograft outcome. Analysis of separate functional SNPs and haplotypes in the FCN2 gene of the donor and recipient did not reveal an association with transplant outcome. Also, the joint effect of the MBL2 and FCN2 genotype was not associated with allograft outcome.This study shows that the genetic profile of the lectin pathway of complement activation of the donor and recipient is not associated with allograft outcome after kidney transplantation. PMID:22173059

Damman, Jeffrey; Kok, Julian L; Snieder, Harold; Leuvenink, Henri G; van Goor, Harry; Hillebrands, Jan-Luuk; van Dijk, Marcory C; Hepkema, Bouke G; Reznichenko, Anna; van den Born, Jaap; de Borst, Martin H; Bakker, Stephan J; Navis, Gerjan J; Ploeg, Rutger J; Seelen, Marc A

2012-02-01

7

Ficolins and the lectin pathway of complement in patients with systemic lupus erythematosus.  

PubMed

The complement system plays a pathophysiological role in systemic lupus erythematosus (SLE). This study aims to investigate whether an association exists between the ficolins that are part of the lectin complement pathway and SLE. EDTA plasma samples from 68 Danish SLE patients and 29 healthy donors were included in the study. Plasma concentrations of Ficolin-1, -2, and -3 were determined in specific sandwich ELISAs. Lectin pathway activity via Ficolin-3 was measured in ELISA on acetylated bovine serum albumin (acBSA) and measured as Ficolin-3 binding and deposition of C4, C3 and the terminal complement complex (TCC). SLE patients had increased levels of Ficolin-3, 21.6?g/ml as compared to 17.0?g/ml in healthy controls (P=0.0098). The Ficolin-1 plasma concentration was negatively correlated with SLE Disease Activity Index (SLEDAI) (Rho=-0.29, P=0.015) and positively correlated to the [Systemic Lupus International Collaborating Clinics (SLICC)/American College of Rheumatology (ACR) Damage Index] (SDI) (Rho=0.27, P=0.026). The Ficolin-1 concentration was also associated with the occurrence of arterial (P=0.0053) but not venous thrombosis (P=0.42). Finally, deposition of C4, C3 and TCC in the Ficolin-3 pathway were all correlated to SLEDAI, respectively (P<0.0076). The Ficolin-1 association to SLEDAI and SDI as well as arterial thrombosis shown in this study suggests that Ficolin-1 may be a potential new biomarker for patients with SLE. Furthermore, Ficolin-3 mediated complement activation may be valuable in monitoring disease activity in SLE patients due to the high sensitivity for complement consumption in the assay independent of the Ficolin-3 concentration. PMID:25069872

Hein, Estrid; Nielsen, Louise Aas; Nielsen, Christoffer T; Munthe-Fog, Lea; Skjoedt, Mikkel-Ole; Jacobsen, Sřren; Garred, Peter

2015-02-01

8

Interaction of lectin pathway of complement-activating pattern recognition molecules with mycobacteria.  

PubMed

We have demonstrated that mannose-binding lectin (MBL) recognizes various slow-growing, pathogenic mycobacteria [Mycobacterium?tuberculosis (MTB), M.?bovis, M.?kansasii, M.?gordonae] as well as non-pathogenic M.?smegmatis. Recognition resulted in activation of the lectin pathway (LP) of complement and an enhancement of phagocytosis (shown for M.?tuberculosis). Although MBL may be considered the main factor activating the LP upon recognition of mycobacteria, involvement of ficolins has also to be considered. Interaction of ficolin-3 with M.?tuberculosis, M.?bovis and M.?kansasii, and ficolin-1 with M.?tuberculosis and M.?bovis was shown for the first time. Binding of recombinant MBL or ficolin-3 to MTB H37 Rv led to the agglutination of bacteria and promoted their phagocytosis, but little effect was apparent with ficolin-1 or ficolin-2. Data from Western blots suggest mannosylated lipoarabinomannan (ManLAM) to be one of the main cell components of slow-growing mycobacteria, involved in LP activation. However, the LP was also activated by other cell fractions. Results presented here supplement considerably the data concerning the ability of complement-activating lectins to interact with mycobacteria. Ficolins (especially ficolin-3) might influence host response to infection and thus have clinical significance, at least as disease modifiers. PMID:25041480

Bartlomiejczyk, M A; Swierzko, A S; Brzostek, A; Dziadek, J; Cedzynski, M

2014-11-01

9

Depressed activation of the lectin pathway of complement in hereditary angioedema  

PubMed Central

The possibility of simultaneous measurement of the classical pathway (CP), mannan-binding lectin (MBL)–lectin pathway (LP) and alternative pathway (AP) of complement activation by the recently developed Wielisa method allowed us to investigate the in vivo significance of the C1-inhibitor (C1INH) in three complement activation pathways. Functional activity of the CP, LP and AP were measured in the sera of 68 adult patients with hereditary angioedema (HAE) and 64 healthy controls. In addition, the level of C1q, MBL, MBL-associated serine protease-2 (MASP-2), C4-, C3- and C1INH was measured by standard laboratory methods. MBL-2 genotypes were determined by polymerase chain reaction. Besides the complement alterations (low CP and C1INH activity, low C4-, C1INH concentrations), which characterize HAE, the level of MASP-2 was also lower (P = 0·0001) in patients compared with controls. Depressed LP activity was found in patients compared with controls (P = 0·0008) in homozygous carriers of the normal MBL genotype (A/A), but not in carriers of variant genotypes (A/O, O/O). Activity of CP correlated with LP in patients (Spearman's r = 0·64; P < 0·0001), but no significant correlation was found in the control group and no correlation with AP was observed. In contrast, the activity of CP and AP correlated (Spearman's r = 0·47; P < 0·0001) in healthy controls, but there was no significant correlation in the HAE patients. We conclude that the activation of LP might also occur in subjects with C1INH deficiency, which is reflected by the low MASP-2 and C4 levels. PMID:18460017

Varga, L; Széplaki, G; Laki, J; Kocsis, A; Kristóf, K; Gál, P; Bajtay, Z; Wieslander, J; Daha, M R; Garred, P; Madsen, H O; Füst, G; Farkas, H

2008-01-01

10

TFPI inhibits lectin pathway of complement activation by direct interaction with MASP-2.  

PubMed

The lectin pathway (LP) of complement has a protective function against invading pathogens. Recent studies have also shown that the LP plays an important role in ischemia/reperfusion (I/R)-injury. MBL-associated serine protease (MASP)-2 appears to be crucial in this process. The serpin C1-inhibitor is the major inhibitor of MASP-2. In addition, aprotinin, a Kunitz-type inhibitor, was shown to inhibit MASP-2 activity in vitro. In this study we investigated whether the Kunitz-type inhibitor tissue factor pathway inhibitor (TFPI) is also able to inhibit MASP-2. Ex vivo LP was induced and detected by C4-deposition on mannan-coated plates. The MASP-2 activity was measured in a fluid-phase chromogenic assay. rTFPI in the absence or presence of specific monoclonal antibodies was used to investigate which TFPI-domains contribute to MASP-2 inhibition. Here, we identify TFPI as a novel selective inhibitor of MASP-2, without affecting MASP-1 or the classical pathway proteases C1s and C1r. Kunitz-2 domain of TFPI is required for the inhibition of MASP-2. Considering the role of MASP-2 in complement-mediated I/R-injury, the inhibition of this protease by TFPI could be an interesting therapeutic approach to limit the tissue damage in conditions such as cerebral stroke, myocardial infarction or solid organ transplantation. PMID:25359215

Keizer, Mischa P; Pouw, Richard B; Kamp, Angela M; Patiwael, Sanne; Marsman, Gerben; Hart, Margreet H; Zeerleder, Sacha; Kuijpers, Taco W; Wouters, Diana

2015-02-01

11

Lyme Borreliosis and Deficient Mannose-Binding Lectin Pathway of Complement.  

PubMed

Risk factors for the widely endemic and much-debated tick-borne infection, Lyme borreliosis (LB), are unknown. The mannose-binding lectin (MBL) pathway of the complement cascade has an essential role in the eradication of Borrelia burgdorferi. A sufficient concentration of biologically active MBL in body fluids is an indicator of proper function of the MBL pathway. In this study, we investigated whether impaired MBL pathway function, represented by reduced serum MBL concentration, predisposes individuals to LB. First, we determined a serum MBL concentration cut-off level associated with diminished MBL pathway function in a group of 201 individuals. Then, we identified 350 borrelia Ab(+) LB patient serum samples and 350 Ab(-) control samples from the archives of our laboratory and measured serum MBL concentrations in both sample groups. The concentration data were analyzed statistically using logistic regression, controlling for MBL cut-off, age, gender, and age and gender interaction. Serum MBL concentrations < 787 and < 445 ng/ml were associated with diminished and deficient MBL pathway function, respectively. Using these cut-offs, diminished (41.4 versus 27.4%, p = 0.0027) and deficient (26.3 versus 17.1%, p = 0.0361) MBL pathway functions were observed statistically more frequently in the LB patient samples than in the control samples. Also, the age-adjusted median serum MBL concentrations were significantly lower in the LB patient samples than in the non-LB controls. Our findings indicate that a deficiency in the MBL pathway of the complement cascade is a risk factor for developing disseminated Ab(+) LB. PMID:25416809

Sajanti, Eeva M; Gröndahl-Yli-Hannuksela, Kirsi; Kauko, Tommi; He, Qiushui; Hytönen, Jukka

2014-11-21

12

The Emerging Role of Complement Lectin Pathway in Trypanosomatids: Molecular Bases in Activation, Genetic Deficiencies, Susceptibility to Infection, and Complement System-Based Therapeutics  

PubMed Central

The innate immune system is evolutionary and ancient and is the pivotal line of the host defense system to protect against invading pathogens and abnormal self-derived components. Cellular and molecular components are involved in recognition and effector mechanisms for a successful innate immune response. The complement lectin pathway (CLP) was discovered in 1990. These new components at the complement world are very efficient. Mannan-binding lectin (MBL) and ficolin not only recognize many molecular patterns of pathogens rapidly to activate complement but also display several strategies to evade innate immunity. Many studies have shown a relation between the deficit of complement factors and susceptibility to infection. The recently discovered CLP was shown to be important in host defense against protozoan microbes. Although the recognition of pathogen-associated molecular patterns by MBL and Ficolins reveal efficient complement activations, an increase in deficiency of complement factors and diversity of parasite strategies of immune evasion demonstrate the unsuccessful effort to control the infection. In the present paper, we will discuss basic aspects of complement activation, the structure of the lectin pathway components, genetic deficiency of complement factors, and new therapeutic opportunities to target the complement system to control infection. PMID:23533355

Evans-Osses, Ingrid; de Messias-Reason, Iara; Ramirez, Marcel I.

2013-01-01

13

Trypanosoma cruzi calreticulin inhibits the complement lectin pathway activation by direct interaction with L-Ficolin.  

PubMed

Trypanosoma cruzi, the agent of Chagas' disease, the sixth neglected tropical disease worldwide, infects 10-12 million people in Latin America. Differently from T. cruzi epimastigotes, trypomastigotes are complement-resistant and infective. CRPs, T-DAF, sialic acid and lipases explain at least part of this resistance. In vitro, T. cruzi calreticulin (TcCRT), a chaperone molecule that translocates from the ER to the parasite surface: (a) Inhibits the human classical complement activation, by interacting with C1, (b) As a consequence, an increase in infectivity is evident and, (c) It inhibits angiogenesis and tumor growth. We report here that TcCRT also binds to the L-Ficolin collagenous portion, thus inhibiting approximately between 35 and 64% of the human complement lectin pathway activation, initiated by L-Ficolin, a property not shared by H-Ficolin. While L-Ficolin binds to 60% of trypomastigotes and to 24% of epimastigotes, 50% of the former and 4% of the latter display TcCRT on their surfaces. Altogether, these data indicate that TcCRT is a parasite inhibitory receptor for Ficolins. The resulting evasive activities, together with the TcCRT capacity to inhibit C1, with a concomitant increase in infectivity, may represent T. cruzi strategies to inhibit important arms of the innate immune response. PMID:24769495

Sosoniuk, Eduardo; Vallejos, Gerardo; Kenawy, Hany; Gaboriaud, Christine; Thielens, Nicole; Fujita, Teizo; Schwaeble, Wilhelm; Ferreira, Arturo; Valck, Carolina

2014-07-01

14

Factors of the Lectin Pathway of Complement Activation and Their Clinical Associations in Neonates  

PubMed Central

This paper summarizes the data concerning soluble defense lectins (mannan-binding lectin, M-ficolin, L-ficolin, and H-ficolin) with the unique ability to activate complement and their associated serine proteases (MASPs) in neonates. The clinical importance of deficiencies of these immune factors is presented in aspects of perinatal mortality, premature births, and low birthweight. Prenatal serum concentrations of L-ficolin, H-ficolin, and MASP-2 (and probably M-ficolin) correlate with gestational age and birthweight. The relationship of serum MBL to gestational age is controversial. The MBL2 genotypes XA/O and O/O (associated with low-serum MBL) are associated with perinatal infections, whereas the high serum MBL-conferring A/A genotypes may be associated with prematurity. Low-serum L-ficolin concentrations, but not low-serum H-ficolin concentrations, are also associated with perinatal infections. Much of the literature is inconsistent, and the relationships reported so far require independent confirmation at both gene and protein levels. Our preliminary conclusion is that these soluble defense lectins play a protective role in the neonate, and that insufficiency of such factors contributes to the adverse consequences of prematurity and low birthweight. PMID:22619494

Cedzynski, Maciej; Swierzko, Anna St.; Kilpatrick, David C.

2012-01-01

15

Revised mechanism of complement lectin-pathway activation revealing the role of serine protease MASP-1 as the exclusive activator of MASP-2  

PubMed Central

The lectin pathway of complement activation is an important component of the innate immune defense. The initiation complexes of the lectin pathway consist of a recognition molecule and associated serine proteases. Until now the autoactivating mannose-binding lectin-associated serine protease (MASP)-2 has been considered the autonomous initiator of the proteolytic cascade. The role of the much more abundant MASP-1 protease was controversial. Using unique, monospecific inhibitors against MASP-1 and MASP-2, we corrected the mechanism of lectin-pathway activation. In normal human serum, MASP-2 activation strictly depends on MASP-1. MASP-1 activates MASP-2 and, moreover, inhibition of MASP-1 prevents autoactivation of MASP-2. Furthermore we demonstrated that MASP-1 produces 60% of C2a responsible for C3 convertase formation. PMID:22691502

Héja, Dávid; Kocsis, Andrea; Dobó, József; Szilágyi, Katalin; Szász, Róbert; Závodszky, Péter; Pál, Gábor; Gál, Péter

2012-01-01

16

Inhibition of the classical and lectin pathway of the complement system by recombinant LAIR-2.  

PubMed

Activation of complement may cause severe tissue damage in antibody-mediated allograft rejection and other antibody-mediated clinical conditions; therefore, novel potent complement inhibitors are needed. Previously, we described binding of the inhibitory receptor LAIR-1 and its soluble family member LAIR-2 to collagen. Here, we investigated binding of LAIR-1 and LAIR-2 to the complement proteins C1q and MBL, which both have collagen-like domains, and evaluated the effect of this binding on complement function. We demonstrate specific binding of recombinant LAIR proteins to both C1q and MBL. Surface plasmon resonance experiments showed that LAIR-2-Fc protein bound C1q and MBL with the highest affinity compared to LAIR-2-HIS. We, therefore, hypothesized that LAIR-2-Fc is a potent complement inhibitor. Indeed, LAIR-2-Fc inhibited C4 fixation to IgG or mannan, reduced activation of C4 by aggregated IgG in plasma and inhibited iC3b deposition on cells. Finally, LAIR-2-Fc inhibited complement-mediated lysis of cells sensitized with anti-HLA antibodies in an ex vivo model for antibody-mediated transplant rejection. Thus, LAIR-2-Fc is an effective novel complement inhibitor for the treatment and prevention of antibody-mediated allograft rejection and antibody-mediated clinical conditions. PMID:24192271

Olde Nordkamp, Marloes J M; Boross, Peter; Yildiz, Cafer; Jansen, J H Marco; Leusen, Jeanette H W; Wouters, Diana; Urbanus, Rolf T; Hack, C Erik; Meyaard, Linde

2014-01-01

17

Heparin-coated cardiopulmonary bypass circuits selectively deplete the pattern recognition molecule ficolin-2 of the lectin complement pathway in vivo.  

PubMed

The complement system can be activated via the lectin pathway by the recognition molecules mannose-binding lectin (MBL) and the ficolins. Ficolin-2 exhibits binding against a broad range of ligands, including biomaterials in vitro, and low ficolin-2 levels are associated with increased risk of infections. Thus, we investigated the biocompatibility of the recognition molecules of the lectin pathway in two different types of cardiopulmonary bypass circuits. Bloods were drawn at five time-points before, during and postoperatively from 30 patients undergoing elective cardiac surgery. Patients were randomized into two groups using different coatings of cardiopulmonary bypass circuits, Phisio® (phosphorylcholine polymer coating) and Bioline® (albumin-heparin coating). Concentrations of MBL, ficolin-1, -2 and -3 and soluble C3a and terminal complement complex (TCC) in plasma samples were measured. Ficolin-3-mediated complement activation potential was evaluated with C4, C3 and TCC as output. There was no significant difference between the two circuit materials regarding MBL, ficolin-1 and -3. In the Bioline® group the ficolin-2 levels decreased significantly after initiation of surgery (P < 0.0001) and remained reduced throughout the sampling period. This was not seen for Phisio®-coated circuits. Ficolin-3-mediated complement activation potential was reduced significantly in both groups after start of operation (P < 0.0001), whereas soluble C3a and TCC in the samples were increased (P < 0.0001). Ficolin-2 was depleted from plasma during cardiac surgery when using heparin-coated bypass circuits and did not reach baseline level 24 h postoperation. These findings may have implications for the postoperative susceptibility to infections in patients undergoing extracorporeal circulation procedures. PMID:25174443

Hein, E; Munthe-Fog, L; Thiara, A S; Fiane, A E; Mollnes, T E; Garred, P

2015-02-01

18

The extracellular adherence protein from Staphylococcus aureus inhibits the classical and lectin pathways of complement by blocking formation of the C3 proconvertase.  

PubMed

The pathogenic bacterium Staphylococcus aureus actively evades many aspects of human innate immunity by expressing a series of small inhibitory proteins. A number of these proteins inhibit the complement system, which labels bacteria for phagocytosis and generates inflammatory chemoattractants. Although the majority of staphylococcal complement inhibitors act on the alternative pathway to block the amplification loop, only a few proteins act on the initial recognition cascades that constitute the classical pathway (CP) and lectin pathway (LP). We screened a collection of recombinant, secreted staphylococcal proteins to determine whether S. aureus produces other molecules that inhibit the CP and/or LP. Using this approach, we identified the extracellular adherence protein (Eap) as a potent, specific inhibitor of both the CP and LP. We found that Eap blocked CP/LP-dependent activation of C3, but not C4, and that Eap likewise inhibited deposition of C3b on the surface of S. aureus cells. In turn, this significantly diminished the extent of S. aureus opsonophagocytosis and killing by neutrophils. This combination of functional properties suggested that Eap acts specifically at the level of the CP/LP C3 convertase (C4b2a). Indeed, we demonstrated a direct, nanomolar-affinity interaction of Eap with C4b. Eap binding to C4b inhibited binding of both full-length C2 and its C2b fragment, which indicated that Eap disrupts formation of the CP/LP C3 proconvertase (C4b2). As a whole, our results demonstrate that S. aureus inhibits two initiation routes of complement by expression of the Eap protein, and thereby define a novel mechanism of immune evasion. PMID:25381436

Woehl, Jordan L; Stapels, Daphne A C; Garcia, Brandon L; Ramyar, Kasra X; Keightley, Andrew; Ruyken, Maartje; Syriga, Maria; Sfyroera, Georgia; Weber, Alexander B; Zolkiewski, Michal; Ricklin, Daniel; Lambris, John D; Rooijakkers, Suzan H M; Geisbrecht, Brian V

2014-12-15

19

Quantitative Characterization of the Activation Steps of Mannan-binding Lectin (MBL)-associated Serine Proteases (MASPs) Points to the Central Role of MASP-1 in the Initiation of the Complement Lectin Pathway*  

PubMed Central

Mannan-binding lectin (MBL)-associated serine proteases, MASP-1 and MASP-2, have been thought to autoactivate when MBL/ficolin·MASP complexes bind to pathogens triggering the complement lectin pathway. Autoactivation of MASPs occurs in two steps: 1) zymogen autoactivation, when one proenzyme cleaves another proenzyme molecule of the same protease, and 2) autocatalytic activation, when the activated protease cleaves its own zymogen. Using recombinant catalytic fragments, we demonstrated that a stable proenzyme MASP-1 variant (R448Q) cleaved the inactive, catalytic site Ser-to-Ala variant (S646A). The autoactivation steps of MASP-1 were separately quantified using these mutants and the wild type enzyme. Analogous mutants were made for MASP-2, and rate constants of the autoactivation steps as well as the possible cross-activation steps between MASP-1 and MASP-2 were determined. Based on the rate constants, a kinetic model of lectin pathway activation was outlined. The zymogen autoactivation rate of MASP-1 is ?3000-fold higher, and the autocatalytic activation of MASP-1 is about 140-fold faster than those of MASP-2. Moreover, both activated and proenzyme MASP-1 can effectively cleave proenzyme MASP-2. MASP-3, which does not autoactivate, is also cleaved by MASP-1 quite efficiently. The structure of the catalytic region of proenzyme MASP-1 R448Q was solved at 2.5 ?. Proenzyme MASP-1 R448Q readily cleaves synthetic substrates, and it is inhibited by a specific canonical inhibitor developed against active MASP-1, indicating that zymogen MASP-1 fluctuates between an inactive and an active-like conformation. The determined structure provides a feasible explanation for this phenomenon. In summary, autoactivation of MASP-1 is crucial for the activation of MBL/ficolin·MASP complexes, and in the proenzymic phase zymogen MASP-1 controls the process. PMID:23386610

Megyeri, Márton; Harmat, Veronika; Major, Balázs; Végh, Ádám; Balczer, Júlia; Héja, Dávid; Szilágyi, Katalin; Datz, Dániel; Pál, Gábor; Závodszky, Péter; Gál, Péter; Dobó, József

2013-01-01

20

A novel peptide inhibitor of classical and lectin complement activation including ABO incompatibility.  

PubMed

Previous experiments from our laboratories have identified peptides derived from the human astrovirus coat protein (CP) that bind C1q and mannose binding lectin (MBL) inhibiting activation of the classical and lectin pathways of complement, respectively. The purpose of this study was to evaluate the function of these coat protein peptides (CPPs) in an in vitro model of complement-mediated disease (ABO incompatibility), preliminarily assess their in vivo complement suppression profile and develop more highly potent derivatives of these molecules. E23A, a 30 amino acid CPP derivative previously demonstrated to inhibit classical pathway activation was able to dose-dependently inhibit lysis of AB erythrocytes treated with mismatched human O serum. Additionally, when injected into rats, E23A inhibited the animals' serum from lysing antibody-sensitized erythrocytes, providing preliminary in vivo functional evidence that this CPP can cross the species barrier to inhibit serum complement activity in rodents. A rational drug design approach was implemented to identify more potent CPP derivatives, resulting in the identification and characterization of a 15 residue peptide (polar assortant (PA)), which demonstrated both superior inhibition of classical complement pathway activation and robust binding to C1q collagen-like tails. PA also inhibited ABO incompatibility in vitro and demonstrated in vivo complement suppression up to 24h post-injection. CPP's ability to inhibit ABO incompatibility in vitro, proof of concept in vivo inhibitory activity in rats and the development of the highly potent PA derivative set the stage for preclinical testing of this molecule in small animal models of complement-mediated disease. PMID:22906481

Mauriello, Clifford T; Pallera, Haree K; Sharp, Julia A; Woltmann, Jon L; Qian, Shizhi; Hair, Pamela S; van der Pol, Pieter; van Kooten, Cees; Thielens, Nicole M; Lattanzio, Frank A; Cunnion, Kenji M; Krishna, Neel K

2013-01-01

21

Essential role of Mannose-binding lectin-associated serine protease-1 in activation of the complement factor D  

PubMed Central

The complement system is an essential component of innate immunity, participating in the pathogenesis of inflammatory diseases and in host defense. In the lectin complement pathway, mannose-binding lectin (MBL) and ficolins act as recognition molecules, and MBL-associated serine protease (MASP) is a key enzyme; MASP-2 is responsible for the lectin pathway activation. The function of other serine proteases (MASP-1 and MASP-3) is still obscure. In this study, we generated a MASP-1– and MASP-3–deficient mouse model (Masp1/3?/?) and found that no activation of the alternative pathway was observed in Masp1/3?/? serum. Mass spectrometric analysis revealed that circulating complement factor D (Df) in Masp1/3?/? mice is a zymogen (pro-Df) with the activation peptide QPRGR at its N terminus. These results suggested that Masp1/3?/? mice failed to convert pro-Df to its active form, whereas it was generally accepted that the activation peptide of pro-Df is removed during its secretion and factor D constitutively exists in an active form in the circulation. Furthermore, recombinant MASP-1 converted pro-Df to the active form in vitro, although the activation mechanism of pro-Df by MASP-1 is still unclear. Thus, it is clear that MASP-1 is an essential protease of both the lectin and alternative complement pathways. PMID:20038603

Ishida, Yumi; Iwaki, Daisuke; Kanno, Kazuko; Suzuki, Toshiyuki; Endo, Yuichi; Homma, Yoshimi; Fujita, Teizo

2010-01-01

22

Evaluation of lectin pathway activity and mannan-binding lectin levels in the course of pregnancy complicated by diabetes type 1, based on the genetic background  

Microsoft Academic Search

Introduction  There are numerous indications that either mannan-binding lectin (MBL) deficiency or its excessive activity are associated\\u000a with adverse pregnancy outcomes. High MBL concentrations and corresponding MBL2 genotypes were shown to be associated with microvascular complications in type 1 diabetes. The aim of this study was to\\u000a evaluate levels of MBL and MBL-dependent activity of the lectin pathway (LP) of complement

Maciej Cedzy?ski; Anna ?wierzko; Agnieszka Szala; Ma?gorzata Sobczak; Katarzyna Cypryk; Jan Wilczy?ski

2009-01-01

23

Polyphosphate suppresses complement via the terminal pathway  

PubMed Central

Polyphosphate, synthesized by all cells, is a linear polymer of inorganic phosphate. When released into the circulation, it exerts prothrombotic and proinflammatory activities by modulating steps in the coagulation cascade. We examined the role of polyphosphate in regulating the evolutionarily related proteolytic cascade complement. In erythrocyte lysis assays, polyphosphate comprising more than 1000 phosphate units suppressed total hemolytic activity with a concentration to reduce maximal lysis to 50% that was 10-fold lower than with monophosphate. In the ion- and enzyme-independent terminal pathway complement assay, polyphosphate suppressed complement in a concentration- and size-dependent manner. Phosphatase-treated polyphosphate lost its ability to suppress complement, confirming that polymer integrity is required. Sequential addition of polyphosphate to the terminal pathway assay showed that polyphosphate interferes with complement only when added before formation of the C5b-7 complex. Physicochemical analyses using native gels, gel filtration, and differential scanning fluorimetry revealed that polyphosphate binds to and destabilizes C5b,6, thereby reducing the capacity of the membrane attack complex to bind to and lyse the target cell. In summary, we have added another function to polyphosphate in blood, demonstrating that it dampens the innate immune response by suppressing complement. These findings further establish the complex relationship between coagulation and innate immunity. PMID:24335501

Wat, Jovian M.; Foley, Jonathan H.; Krisinger, Michael J.; Ocariza, Linnette Mae; Lei, Victor; Wasney, Gregory A.; Lameignere, Emilie; Strynadka, Natalie C.; Smith, Stephanie A.; Morrissey, James H.

2014-01-01

24

Lectin Complement Protein Collectin 11 (CL-K1) and Susceptibility to Urinary Schistosomiasis  

PubMed Central

Background Urinary Schistosomiasis is a neglected tropical disease endemic in many sub Saharan -African countries. Collectin Kidney 1 (CL-K1, encoded by COLEC11 on chromosome 2p25.3), a member of the vertebrate C-type lectin super family, has recently been identified as pattern-recognition molecule (PRR) of the lectin complement pathway. CL-K1 is preferentially expressed in the kidneys, but also in other organs and it is considered to play a role in host defense to some infectious agents. Schistosome teguments are fucosylated and CL-K1 has, through its collagen-like domain, a high binding affinity to fucose. Methodology/Principal Findings We utilized a Nigerian study group consisting of 167 Schistosoma haematobium infected individuals and 186 matched healthy subjects, and investigated the contribution of CL-K1 deficiency and of COLEC11 polymorphisms to infection phenotype. Higher CL-K1 serum levels were associated with decreased risk of schistosome infection (Pcorr = 0.0004). CL-K1 serum levels were differentially distributed between the COLEC11 genotypes and haplotypes observed. The non-synonymous variant p.R216H was associated with the occurrence of schistosomiasis (OR = 0.44, 95%CI = 0.22–0.72, Pcorr = 0.0004). The reconstructed COLEC11*TCCA haplotypes were associated with higher CL-K1 serum levels (P = 0.002) and with decreased schistosomiasis (OR = 0.38, 95%CI = 0.23–0.63, Pcorr = 0.0001). Conclusions In agreement with findings from our earlier published study, our findings support the observation that CL-K1 and their functional variants may be host factors associated with protection in schistosomiasis and may be a useful marker for further investigations. PMID:25807310

Antony, Justin S.; Ojurongbe, Olusola; Kremsner, Peter G.; Velavan, Thirumalaisamy P.

2015-01-01

25

A novel IgM-H-ficolin complement pathway to attack allogenic cancer cells in vitro.  

PubMed

The pentameric serum IgMs are critical to immune defense and surveillance through cytotoxicity against microbes and nascent cancer cells. Ficolins, a group of oligomeric lectins with an overall structure similar to C1q and mannose-binding lectin (MBL) participate in microbe infection and apoptotic cell clearance by activating the complement lectin pathway or a primitive opsonophagocytosis. It remains unknown whether serum IgMs interplay with ficolins in cancer immunosurveillance. Here we report a natural cancer killing of different types of cancer cells by sera from a healthy human population mediated by a novel IgM-H-ficolin complement activation pathway. We demonstrate for the first time that H-ficolin bound to a subset of IgMs in positive human sera and IgM-H-ficolin deposited on cancer cells to activate complement attack in cancer cells. Our data suggest that the IgM-H-ficolin -mediated complement activation pathway may be another defensive strategy for human cancer immunosurveillance. PMID:25592840

Lei, Xiaoying; Liu, Chaoxu; Azadzoi, Kazem; Li, Cuiling; Lu, Fan; Xiang, An; Sun, Jianbin; Guo, Yanhai; Zhao, Qingchuan; Yan, Zhen; Yang, Jinghua

2015-01-01

26

A novel IgM–H-Ficolin complement pathway to attack allogenic cancer cells in vitro  

PubMed Central

The pentameric serum IgMs are critical to immune defense and surveillance through cytotoxicity against microbes and nascent cancer cells. Ficolins, a group of oligomeric lectins with an overall structure similar to C1q and mannose-binding lectin (MBL) participate in microbe infection and apoptotic cell clearance by activating the complement lectin pathway or a primitive opsonophagocytosis. It remains unknown whether serum IgMs interplay with ficolins in cancer immunosurveillance. Here we report a natural cancer killing of different types of cancer cells by sera from a healthy human population mediated by a novel IgM–H-ficolin complement activation pathway. We demonstrate for the first time that H-ficolin bound to a subset of IgMs in positive human sera and IgM–H-ficolin deposited on cancer cells to activate complement attack in cancer cells. Our data suggest that the IgM–H-ficolin -mediated complement activation pathway may be another defensive strategy for human cancer immunosurveillance. PMID:25592840

Lei, Xiaoying; Liu, Chaoxu; Azadzoi, Kazem; Li, Cuiling; Lu, Fan; Xiang, An; Sun, Jianbin; Guo, Yanhai; Zhao, Qingchuan; Yan, Zhen; Yang, Jinghua

2015-01-01

27

New Insights into the Role of Ficolins in the Lectin Pathway of Innate Immunity.  

PubMed

In the innate immune system, a variety of recognition molecules provide the first-line host defense to prevent infection and maintain endogenous homeostasis. Ficolin is a soluble recognition molecule, which senses pathogen-associated molecular patterns on microbes and aberrant sugar structures on self-cells. It consists of a collagen-like stalk and a globular fibrinogen-like domain, the latter binding to carbohydrates such as N-acetylglucosamine. Ficolins have been widely identified in animals from higher invertebrates to mammals. In mammals, ficolins form complexes with mannose-binding lectin-associated serine proteases (MASPs), and ficolin-MASP complexes trigger complement activation via the lectin pathway. Once activated, complement mediates many immune responses including opsonization, phagocytosis, and cytokine production. Although the precise function of each ficolin is still under investigation, accumulating information suggests that ficolins have a crucial role in host defense by recognizing a variety of microorganisms and interacting with effector proteins. PMID:25805122

Endo, Yuichi; Matsushita, Misao; Fujita, Teizo

2015-01-01

28

Functional characterization of mannose-binding lectin in zebrafish: implication for a lectin-dependent complement system in early embryos.  

PubMed

The lectin pathway involves recognition of pathogen-associated molecular patterns by mannose-binding lectin (MBL), and the subsequent activation of associated enzymes, termed MBL-associated serine proteases (MASPs). In this study, we demonstrate that the transcript of MBL gene is present in the early embryo of zebrafish, and MBL protein is also present in the embryo. In addition, we show that recombinant zebrafish MBL was able to bind the Gram-negative bacterium Escherichia coli and the Gram-positive bacterium Staphylococcus aureus, and rMBL was able to promote the phagocytosis of E. coli and S. aureus by macrophages, indicating that like mammalian MBL, zebrafish MBL performs a dual function in both pattern recognition and opsonization. Importantly, we show that microinjection of anti-MBL antibody into the early developing embryos resulted in a significantly increased mortality in the embryos challenged with Aeromonas hydrophila (pathogenic to zebrafish); and injection of rMBL into the embryos (resulting in increase in MBL in the embryo) markedly promoted their resistance to A. hydrophila; and this promoted bacterial resistance was significantly reduced by the co-injection of anti-MBL antibody with rMBL but not by the injection of anti-actin antibody with rMBL. These suggest that the lectin pathway may be already functional in the early embryos in zebrafish before their immune system is fully matured, protecting the developing embryos from microbial infection. This work provides a new angle to understand the immune role of the lectin pathway in early development of animals. PMID:24858663

Yang, Lili; Bu, Lingzhen; Sun, Weiwei; Hu, Lili; Zhang, Shicui

2014-10-01

29

The Alternative and Terminal Pathways of Complement Mediate Post-Traumatic Spinal Cord Inflammation and Injury  

PubMed Central

Complement is implicated in the inflammatory response and the secondary neuronal damage that occurs after traumatic spinal cord injury (SCI). Complement can be activated by the classical, lectin, or alternative pathways, all of which share a common terminal pathway that culminates in formation of the cytolytic membrane attack complex (MAC). Here, we investigated the role of the alternative and terminal complement pathways in SCI. Mice deficient in the alternative pathway protein factor B (fB) were protected from traumatic SCI in terms of reduced tissue damage and demyelination, reduced inflammatory cell infiltrate, and improved functional recovery. In a clinically relevant paradigm, treatment of mice with an anti-fB mAb resulted in similarly improved outcomes. These improvements were associated with decreased C3 and fB deposition. On the other hand, deficiency of CD59, an inhibitor of the membrane attack complex, resulted in significantly increased injury and impaired functional recovery compared to wild-type mice. Increased injury in CD59-deficient mice was associated with increased MAC deposition, while levels of C3 and fB were unaffected. These data indicate key roles for the alternative and terminal complement pathways in the pathophysiology of SCI. Considering a previous study demonstrating an important role for the classical pathway in promoting SCI, it is likely that the alternative pathway plays a critical role in amplifying classical pathway initiated complement activation. PMID:20952585

Qiao, Fei; Atkinson, Carl; Kindy, Mark S.; Shunmugavel, Anandakumar; Morgan, B. Paul; Song, Hongbin; Tomlinson, Stephen

2010-01-01

30

Continual Low-Level Activation of the Classical Complement Pathway  

PubMed Central

There is evidence that the classical complement pathway may be activated via a “C1-tickover” mechanism, analogous to the C3-tickover of the alternative pathway. We have quantitated and characterized this pathway of complement activation. Analysis of freshly collected mouse and human plasma revealed that spontaneous C3 activation rapidly occurred with the generation of C3 fragments in the plasma. By the use of complement- and Ig-deficient mice it was found that C1q, C4, C2, and plasma Ig were all required for this spontaneous C3 activation, with the alternative complement pathway further amplifying C3 fragment generation. Study of plasma from a human with C1q deficiency before and after therapeutic C1q infusion confirmed the existence of a similar pathway for complement activation in humans. Elevated levels of plasma C3 were detected in mice deficient in complement components required for activation of either the classical or alternative complement pathways, supporting the hypothesis that there is continuous complement activation and C3 consumption through both these pathways in vivo. Blood stasis was found to stimulate C3 activation by classical pathway tick-over. This antigen-independent mechanism for classical pathway activation may augment activation of the complement system at sites of inflammation and infarction. PMID:11560991

Manderson, Anthony P.; Pickering, Matthew C.; Botto, Marina; Walport, Mark J.; Parish, Christopher R.

2001-01-01

31

Recombinant form of human wild type mannan-binding lectin (MBL/A) but not its structural variant (MBL/C) promotes phagocytosis of zymosan by activating complement.  

PubMed

Mannan-binding lectin (MBL) mediates innate immune responses, such as activation of the complement lectin pathway and phagocytosis, to help fight infections. In the present study, employing recombinant forms of human MBL (rMBL), the role of wild type MBL (rMBL/A) and its structural variant rMBL/C in mediating THP-1 phagocytosis of fluorescent-labeled zymosan was examined and compared to MBL purified from human plasma (pMBL/A). Flow cytometric analyses revealed that opsonization of zymosan with rMBL/A and pMBL/A (0.5-30microg/ml) resulted in a 1.9- and 2.7-fold enhancement in its uptake by THP-1 cells in the presence of serum that was depleted of both MBL and the classical pathway component, C1q (MBL/C1q Dpl serum). In contrast, no enhancement in phagocytosis was observed when zymosan was opsonized with rMBL/C. Addition of MBL monoclonal antibody, EDTA, or mannan to the opsonization reaction mixture inhibited THP-1 phagocytosis of pMBL/A opsonized zymosan. Heat inactivation of MBL/C1q Dpl serum abolished the 2-fold increase in phagocytosis and in the absence of serum the direct opsonic activity of MBL did not contribute significantly to the uptake of zymosan into THP-1 cells. Activation products of complement components C3 and C4 were deposited on zymosan opsonized with pMBL/A and rMBL/A but not rMBL/C indicating that MBL-mediated phagocytosis of zymosan requires activation of the complement lectin pathway. The findings imply that impaired MBL-mediated phagocytosis may put individuals homozygous for the mutant allele MBL/C but not wild type MBL/A at increased risk to infections such as yeast. PMID:20579738

Rajagopalan, Rema; Nyaundi, Takazvida; Salvi, Veena P; Rawal, Nenoo

2010-09-01

32

The complement system: history, pathways, cascade and inhibitors  

PubMed Central

Since its discovery in the 19th century, the complement system has developed into a clinically significant entity. The complement system has been implicated in a variety of clinical conditions, from autoimmune diseases to ischemia–reperfusion injury in transplantation. This article charts the historical progress of our understanding of the complement system and provides a synopsis on the activation pathways and its inherent regulators. PMID:24672678

Nesargikar, P. N.; Spiller, B.; Chavez, R.

2012-01-01

33

Activated complement classical pathway in a murine model of oxygen-induced retinopathy  

PubMed Central

AIM To investigate whether the complement system is involved in a murine model of oxygen-induced retinopathy (OIR). METHODS Forty C57BL/6J newborn mice were divided randomly into OIR group and control group. OIR was induced by exposing mice to 75%±2% oxygen from postnatal 7d (P7) to P12 and then recovered in room air. For the control group, the litters were raised in room air. At the postnatal 17d (P17), gene expressions of the complement components of the classical pathway (CP), the mannose-binding lectin (MBL) pathway and the alternative pathway (AP) in the retina were determined by quantitative real-time polymerase chain reaction (RT-PCR). Retinal protein expressions of the key components in the CP were examined by Western blotting. RESULTS Whole mounted retina in the OIR mice showed area of central hypoperfusion in both superficial and deep layers and neovascular tufts in the periphery. The expressions of C1qb and C4b genes in the OIR retina were significantly higher than those of the controls. The expression of retinal complement factor B (CFB) gene in OIR mice was significantly lower than those of the controls. However, the expressions of C3 and complement factor H (CFH) genes were higher. The protein synthesis of the key components involved in the CP (C1q, C4 and C3) were also significantly higher in OIR mouse retina. Although MBL-associated serine protease 1 (MASP1) and MASP2 were detected in both the OIR and the control groups, the expressions were weak and the difference between the two groups was not significant. CONCLUSION Our data suggest that the complement system CP is activated during the pathogenesis of murine model of OIR. PMID:25709901

Tao, Xue-Ying; Zheng, Shi-Jie; Lei, Bo

2015-01-01

34

Peptide Inhibitor of Complement C1, a Novel Suppressor of Classical Pathway Activation: Mechanistic Studies and Clinical Potential  

PubMed Central

The classical pathway of complement plays multiple physiological roles including modulating immunological effectors initiated by adaptive immune responses and an essential homeostatic role in the clearance of damaged self-antigens. However, dysregulated classical pathway activation is associated with antibody-initiated, inflammatory diseases processes like cold agglutinin disease, acute intravascular hemolytic transfusion reaction (AIHTR), and acute/hyperacute transplantation rejection. To date, only one putative classical pathway inhibitor, C1 esterase inhibitor (C1-INH), is currently commercially available and its only approved indication is for replacement treatment in hereditary angioedema, which is predominantly a kinin pathway disease. Given the variety of disease conditions in which the classical pathway is implicated, development of therapeutics that specifically inhibits complement initiation represents a major unmet medical need. Our laboratory has identified a peptide that specifically inhibits the classical and lectin pathways of complement. In vitro studies have demonstrated that these peptide inhibitors of complement C1 (PIC1) bind to the collagen-like region of the initiator molecule of the classical pathway, C1q. PIC1 binding to C1q blocks activation of the associated serine proteases (C1s–C1r–C1r–C1s) and subsequent downstream complement activation. Rational design optimization of PIC1 has resulted in the generation of a highly potent derivative of 15 amino acids. PIC1 inhibits classical pathway mediated complement activation in ABO incompatibility in vitro and inhibiting classical pathway activation in vivo in rats. This review will focus on the pre-clinical development of PIC1 and discuss its potential as a therapeutic in antibody-mediated classical pathway disease, specifically AIHTR. PMID:25202312

Sharp, Julia A.; Whitley, Pamela H.; Cunnion, Kenji M.; Krishna, Neel K.

2014-01-01

35

The 'involution' of mannose-binding lectin  

Microsoft Academic Search

Mannose-binding lectin (MBL) acts as a serum opsonin in innate immune defense and induces complement activation by the lectin pathway. In humans, low levels of functional serum MBL are caused by the dominant action of three single nucleotide substitutions in exon 1 that disrupt the glycine-rich backbone structure of the protein. The presence of common MBL variant alleles is associated

Jeanette Seyfarth; Peter Garred; Hans O. Madsen

2005-01-01

36

Novel Scabies Mite Serpins Inhibit the Three Pathways of the Human Complement System  

PubMed Central

Scabies is a parasitic infestation of the skin by the mite Sarcoptes scabiei that causes significant morbidity worldwide, in particular within socially disadvantaged populations. In order to identify mechanisms that enable the scabies mite to evade human immune defenses, we have studied molecules associated with proteolytic systems in the mite, including two novel scabies mite serine protease inhibitors (SMSs) of the serpin superfamily. Immunohistochemical studies revealed that within mite-infected human skin SMSB4 (54 kDa) and SMSB3 (47 kDa) were both localized in the mite gut and feces. Recombinant purified SMSB3 and SMSB4 did not inhibit mite serine and cysteine proteases, but did inhibit mammalian serine proteases, such as chymotrypsin, albeit inefficiently. Detailed functional analysis revealed that both serpins interfered with all three pathways of the human complement system at different stages of their activation. SMSB4 inhibited mostly the initial and progressing steps of the cascades, while SMSB3 showed the strongest effects at the C9 level in the terminal pathway. Additive effects of both serpins were shown at the C9 level in the lectin pathway. Both SMSs were able to interfere with complement factors without protease function. A range of binding assays showed direct binding between SMSB4 and seven complement proteins (C1, properdin, MBL, C4, C3, C6 and C8), while significant binding of SMSB3 occurred exclusively to complement factors without protease function (C4, C3, C8). Direct binding was observed between SMSB4 and the complement proteases C1s and C1r. However no complex formation was observed between either mite serpin and the complement serine proteases C1r, C1s, MASP-1, MASP-2 and MASP-3. No catalytic inhibition by either serpin was observed for any of these enzymes. In summary, the SMSs were acting at several levels mediating overall inhibition of the complement system and thus we propose that they may protect scabies mites from complement-mediated gut damage. PMID:22792350

Mika, Angela; Reynolds, Simone L.; Mohlin, Frida C.; Willis, Charlene; Swe, Pearl M.; Pickering, Darren A.; Halilovic, Vanja; Wijeyewickrema, Lakshmi C.; Pike, Robert N.; Blom, Anna M.; Kemp, David J.; Fischer, Katja

2012-01-01

37

Essential Role of Complement Mannose-Binding Lectin-Associated Serine Proteases-1/3 in the Murine Collagen Antibody-Induced Model of Inflammatory Arthritis  

PubMed Central

Gene-targeted mice deficient in the complement mannose-binding lectin-associated serine protease-1 and -3 (MASP1/3?/?) express only the zymogen of factor D (pro-factor D [pro-Df]), a necessary component of the alternative pathway (AP). We used the murine collagen Ab-induced arthritis (CAIA) model, in which the AP is unique among complement pathways in being both necessary and sufficient for disease induction, to determine whether MASP-1/3 are required in vivo for the development of tissue injury. Disease activity scores, complement C3 tissue deposition in the joint, and histopathologic injury scores were markedly decreased in MASP1/3?/? as compared with wild-type (WT) mice. MASP-1 protein was immunochemically localized to synovial cells of knees of WT mice with arthritis. Pro-Df was present in both synovial cells and chondrocytes of knees of WT and MASP1/3?/? mice without arthritis, with increased amounts present in synovial cells of WT mice with CAIA. No conversion of pro-Df to mature Df was detectable in the serum of MASP1/3?/? mice during the evolution of CAIA. C3 activation and deposition as well as C5a generation induced in vitro by adherent anti-type II collagen mAbs were absent using sera from MASP1/3?/? mice under conditions in which only the AP was active. The addition of human Df fully reconstituted in vitro C3 activation and C5a generation using sera from MASP1/3?/? mice. Our studies demonstrate for the first time, to our knowledge, the absolute requirement for the activity of MASP-1 protein in autoimmune-associated inflammatory tissue injury in vivo through activation of the AP of complement by cleavage of pro-Df to mature Df. PMID:20870940

Banda, Nirmal K.; Takahashi, Minoru; Levitt, Brandt; Glogowska, Magdalena; Nicholas, Jessica; Takahashi, Kazue; Stahl, Gregory L.; Fujita, Teizo; Arend, William P.; Holers, V. Michael

2011-01-01

38

Differential complement activation pathways promote C3b deposition on native and acetylated LDL thereby inducing lipoprotein binding to the complement receptor 1.  

PubMed

Lipoproteins can induce complement activation resulting in opsonization and binding of these complexes to complement receptors. We investigated the binding of opsonized native LDL and acetylated LDL (acLDL) to the complement receptor 1 (CR1). Binding of complement factors C3b, IgM, C1q, mannose-binding lectin (MBL), and properdin to LDL and acLDL were investigated by ELISA. Subsequent binding of opsonized LDL and acLDL to CR1 on CR1-transfected Chinese Hamster Ovarian cells (CHO-CR1) was tested by flow cytometry. Both native LDL and acLDL induced complement activation with subsequent C3b opsonization upon incubation with normal human serum. Opsonized LDL and acLDL bound to CR1. Binding to CHO-CR1 was reduced by EDTA, whereas MgEGTA only reduced the binding of opsonized LDL, but not of acLDL suggesting involvement of the alternative pathway in the binding of acLDL to CR1. In vitro incubations showed that LDL bound C1q, whereas acLDL bound to C1q, IgM, and properdin. MBL did neither bind to LDL nor to acLDL. The relevance of these findings was demonstrated by the fact that ex vivo up-regulation of CR1 on leukocytes was accompanied by a concomitant increased binding of apolipoprotein B-containing lipoproteins to leukocytes without changes in LDL-receptor expression. In conclusion, CR1 is able to bind opsonized native LDL and acLDL. Binding of LDL to CR1 is mediated via the classical pathway, whereas binding of acLDL is mediated via both the classical and alternative pathways. Binding of lipoproteins to CR1 may be of clinical relevance due to the ubiquitous cellular distribution of CR1. PMID:25349208

Klop, Boudewijn; van der Pol, Pieter; van Bruggen, Robin; Wang, Yanan; de Vries, Marijke A; van Santen, Selvetta; O'Flynn, Joseph; van de Geijn, Gert-Jan M; Njo, Tjin L; Janssen, Hans W; de Man, Peter; Jukema, J Wouter; Rabelink, Ton J; Rensen, Patrick C N; van Kooten, Cees; Cabezas, Manuel Castro

2014-12-19

39

Eosinophil granule cationic proteins regulate the classical pathway of complement.  

PubMed Central

Major basic protein, the primary constituent of eosinophil granules, regulates the alternative and classical pathways of complement. Major basic protein and other eosinophil granule cationic proteins, which are important in mediating tissue damage in allergic disease, regulate the alternative pathway by interfering with C3b interaction with factor B to assemble an alternative pathway C3 convertase. In the present study, eosinophil peroxidase, eosinophil cationic protein and eosinophil-derived neurotoxin, as well as major basic protein, were examined for capacity to regulate the classical pathway. Eosinophil peroxidase, eosinophil cationic protein and major basic protein inhibited formation of cell-bound classical pathway C3 convertase (EAC1,4b,2a), causing 50% inhibition of complement-mediated lysis at about 0.19, 0.75 and 0.5 micrograms/10(7) cellular intermediates, respectively. Eosinophil-derived neurotoxin had no activity on this pathway of complement. The eosinophil granule proteins were examined for activity on the formation of the membrane attack complex. Major basic protein and eosinophil cationic protein had no activity on terminal lysis. In contrast, eosinophil peroxidase inhibited lysis of EAC1,4b,2a,3b,5b, but had only minimal activity on later events in complement lysis. These polycations were then examined to determine the site(s) at which they regulated the early classical pathway. Eosinophil granule polycationic proteins: (1) reduced the Zmax at all time points but had only minimal effect on the Tmax during the formation of the classical pathway C3 convertase (EAC1,4b,2a); (2) inhibited formation of EAC1,4b,2a proportional to C4 but independent of C2 concentration; (3) inhibited fluid phase formation of C1,4b,2a, as reflected by a decrease in C1-induced consumption of C2 over time; and (4) inhibited C1 activity over time without a direct effect on either C4 or C2. These observations suggest that polycations regulate the early classical pathway by interfering with C1 and may exert this activity in vivo. PMID:7750997

Weiler, J M; Edens, R E; Bell, C S; Gleich, G J

1995-01-01

40

Carbamylation of immunoglobulin abrogates activation of the classical complement pathway  

PubMed Central

Post-translational modifications of proteins significantly affect their structure and function. The carbamylation of positively charged lysine residues to form neutral homoitrulline occurs primarily under inflammatory conditions through myeloperoxidase-dependent cyanate (CNO?) formation. We analyzed the pattern of human IgG1 carbamylation under inflammatory conditions and the effects that this modification has on the ability of antibodies to trigger complement activation via the classical pathway. We found that the lysine residues of IgG1 are rapidly modified after brief exposure to CNO?. Interestingly, modifications were not random, but instead limited to only few lysines within the hinge area and the N-terminal fragment of the CH2 domain. A complement activation assay combined with mass spectrometry analysis revealed a highly significant inverse correlation between carbamylation of several key lysine residues within the hinge region and N-terminus of the CH2 domain and the proper binding of C1q to human IgG1 followed by subsequent complement activation. This severely hindered complement-dependent cytotoxicity of therapeutic IgG1. The reaction can apparently occur in vivo, as we found carbamylated antibodies in synovial fluid from rheumatoid arthritis patients. Taken together, our data suggest that carbamylation has a profound impact on the complement-activating ability of IgG1 and reveals a pivotal role for previously uncharacterized lysine residues in this process. PMID:25130613

Koro, Catalin; Bielecka, Ewa; Dahl-Knudsen, Anders; Enghild, Jan J; Scavenius, Carsten; Brun, Johan G; Binder, Veronika; Hellvard, Annelie; Bergum, Brith; Jonsson, Roland; Potempa, Jan; Blom, Anna M; Mydel, Piotr

2014-01-01

41

Therapeutic Inhibition of the Alternative Complement Pathway Attenuates Chronic EAE  

PubMed Central

Previous studies from our laboratory using complement-mutant mice demonstrated that the alternative pathway is the dominant activation pathway responsible for complement-mediated pathology in demyelinating disease. Using a well-characterized inhibitory monoclonal antibody (mAb 1379) directed against mouse factor B, we assessed the therapeutic value of inhibiting the alternative complement pathway in experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. Administration of anti-factor B antibody to mice prior to the onset of clinical signs of active EAE had no affect on the onset or acute phase of disease, but significantly attenuated the chronic phase of disease resulting in reduced cellular infiltration, inflammation and demyelination in antibody-treated mice. Attenuation of the chronic phase of disease was long lasting even though antibody administration was terminated shortly after disease onset. Chronic disease was also attenuated in transferred EAE when anti-factor B antibody was administered before or after disease onset. Similar levels of disease attenuation were observed in transferred EAE using MOG-specific encephalitogenic T cells. These studies demonstrate the therapeutic potential for inhibition of factor B in the chronic phase of demyelinating disease, where treatment options are limited. PMID:23337717

Hu, Xianzhen; Holers, V. Michael; Thurman, Joshua M.; Schoeb, Trent R.; Ramos, Theresa N; Barnum, Scott R.

2013-01-01

42

A metalloproteinase karilysin present in the majority of Tannerella forsythia isolates inhibits all pathways of the complement system1  

PubMed Central

Tannerella forsythia is a poorly studied pathogen despite being one of the main causes of periodontitis, which is an inflammatory disease of the supporting structures of the teeth. We found that despite being recognized by all complement pathways T. forsythia is resistant to killing by human complement, which is present at up to 70% of serum concentration in gingival crevicular fluid. Incubation of human serum with karilysin, a metalloproteinase of T. forsythia, resulted in a decrease in bactericidal activity of the serum. T. forsythia strains expressing karilysin at higher levels were more resistant than low expressing strain. Furthermore, the low expressing strain was significantly more opsonized with C3b and membrane attack complex from serum compared to the other strains. The high expressing strain was more resistant to killing in human blood. The protective effect of karilysin against serum bactericidal activity was attributable to its ability to inhibit complement at several stages. The classical and lectin complement pathways were inhibited due to the efficient degradation of mannose-binding lectin, ficolin-2, ficolin-3 and C4 by karilysin, while inhibition of the terminal pathway was caused by degradation of C5. Interestingly, karilysin was able to release biologically active C5a peptide in human plasma and induce migration of neutrophils. Importantly, we detected the karilysin gene in over 90% of gingival crevicular fluid samples containing T. forsythia obtained from patients with periodontitis. Taken together, the newly characterized karilysin appears to be an important virulence factor of T. forsythia and might have several important implications for immune evasion. PMID:22287711

Jusko, Monika; Potempa, Jan; Karim, Abdulkarim Y.; Ksiazek, Miroslaw; Riesbeck, Kristian; Garred, Peter; Eick, Sigrun; Blom, Anna M.

2012-01-01

43

An amphioxus gC1q protein binds human IgG and initiates the classical pathway: Implications for a C1q-mediated complement system in the basal chordate.  

PubMed

The origin of the classical complement pathway remains open during chordate evolution. A C1q-like member, BjC1q, was identified in the basal chordate amphioxus. It is predominantly expressed in the hepatic caecum, hindgut, and notochord, and is significantly upregulated following challenge with bacteria or lipoteichoic acid and LPS. Recombinant BjC1q and its globular head domain specifically interact with lipoteichoic acid and LPS, but BjC1q displays little lectin activity. Moreover, rBjC1q can assemble to form the high molecular weight oligomers necessary for binding to proteases C1r/C1s and for complement activation, and binds human C1r/C1s/mannan-binding lectin-associated serine protease-2 as well as amphioxus serine proteases involved in the cleavage of C4/C2, and C3 activation. Importantly, rBjC1q binds with human IgG as well as an amphioxus Ig domain containing protein, resulting in the activation of the classical complement pathway. This is the first report showing that a C1q-like protein in invertebrates is able to initiate classical pathway, raising the possibility that amphioxus possesses a C1q-mediated complement system. It also suggests a new scenario for the emergence of the classical complement pathway, in contrast to the proposal that the lectin pathway evolved into the classical pathway. PMID:25174509

Gao, Zhan; Li, Mengyang; Ma, Jie; Zhang, Shicui

2014-12-01

44

Aluminum Hydroxide Adjuvant Differentially Activates the Three Complement Pathways with Major Involvement of the Alternative Pathway  

PubMed Central

Al(OH)3 is the most common adjuvant in human vaccines, but its mode of action remains poorly understood. Complement involvement in the adjuvant properties of Al(OH)3 has been suggested in several reports together with a depot effect. It is here confirmed that Al(OH)3 treatment of serum depletes complement components and activates the complement system. We show that complement activation by Al(OH)3 involves the three major pathways by monitoring complement components in Al(OH)3-treated serum and in Al(OH)3-containing precipitates. Al(OH)3 activation of complement results in deposition of C3 cleavage products and membrane attack complex (MAC) and in generation of the anaphylatoxins C3a and C5a. Complement activation was time dependent and inhibited by chelation with EDTA but not EGTA+Mg2+. We thus confirm that Al(OH)3 activates the complement system and show that the alternative pathway is of major importance. PMID:24040248

Güven, Esin; Duus, Karen; Laursen, Inga; Hřjrup, Peter; Houen, Gunnar

2013-01-01

45

Complement Alternative Pathway Activation in Human Nonalcoholic Steatohepatitis  

PubMed Central

The innate immune system plays a major role in the pathogenesis of nonalcoholic steatohepatitis (NASH). Recently we reported complement activation in human NASH. However, it remained unclear whether the alternative pathway of complement, which amplifies C3 activation and which is frequently associated with pathological complement activation leading to disease, was involved. Here, alternative pathway components were investigated in liver biopsies of obese subjects with healthy livers (n?=?10) or with NASH (n?=?12) using quantitative PCR, Western blotting, and immunofluorescence staining. Properdin accumulated in areas where neutrophils surrounded steatotic hepatocytes, and colocalized with the C3 activation product C3c. C3 activation status as expressed by the C3c/native C3 ratio was 2.6-fold higher (p<0.01) in subjects with NASH despite reduced native C3 concentrations (0.94±0.12 vs. 0.57±0.09; p<0.01). Hepatic properdin levels positively correlated with levels of C3c (rs?=?0.69; p<0.05) and C3c/C3 activation ratio (rs?=?0.59; p<0.05). C3c, C3 activation status (C3c/C3 ratio) and properdin levels increased with higher lobular inflammation scores as determined according to the Kleiner classification (C3c: p<0.01, C3c/C3 ratio: p<0.05, properdin: p<0.05). Hepatic mRNA expression of factor B and factor D did not differ between subjects with healthy livers and subjects with NASH (factor B: 1.00±0.19 vs. 0.71±0.07, p?=?0.26; factor D: 1.00±0.21 vs. 0.66±0.14, p?=?0.29;). Hepatic mRNA and protein levels of Decay Accelerating Factor tended to be increased in subjects with NASH (mRNA: 1.00±0.14 vs. 2.37±0.72; p?=?0.22; protein: 0.51±0.11 vs. 1.97±0.67; p?=?0.28). In contrast, factor H mRNA was downregulated in patients with NASH (1.00±0.09 vs. 0.71±0.06; p<0.05) and a similar trend was observed with hepatic protein levels (1.12±0.16 vs. 0.78±0.07; p?=?0.08). Collectively, these data suggest a role for alternative pathway activation in driving hepatic inflammation in NASH. Therefore, alternative pathway factors may be considered attractive targets for treating NASH by inhibiting complement activation. PMID:25299043

Segers, Filip M.; Verdam, Froukje J.; de Jonge, Charlotte; Boonen, Bas; Driessen, Ann; Shiri-Sverdlov, Ronit; Bouvy, Nicole D.; Greve, Jan Willem M.; Buurman, Wim A.; Rensen, Sander S.

2014-01-01

46

Mannose binding lectin plays a crucial role in innate immunity against yeast by enhanced complement activation and enhanced uptake of polymorphonuclear cells  

PubMed Central

Background Mannose binding lectin (MBL) is an important host defence protein against opportunistic fungal pathogens. This carbohydrate-binding protein, an opsonin and lectin pathway activator, binds through multiple lectin domains to the repeating sugar arrays displayed on the surface of a wide range of clinically relevant microbial species. We investigated the contribution of MBL to antifungal innate immunity towards C. parapsilosis in vitro. Results High avidity binding was observed between MBL and C. albicans and C. parapsilosis. Addition of MBL to MBL deficient serum increased the deposition of C4 and C3b and enhanced the uptake of C. albicans, C. parapsilosis and acapsular C. neoformans by polymorphonuclear cells (PMNs). Compared to other microorganisms, such as Escherichia coli, Staphylococcus aureus and Cryptococcus neoformans, C. parapsilosis and Candida albicans were potent activators of the lectin pathway. Conclusion Our results suggest that MBL plays a crucial role in the innate immunity against infections caused by yeast by increasing uptake by PMN. PMID:19094203

van Asbeck, Eveline C; Hoepelman, Andy IM; Scharringa, Jelle; Herpers, Bjorn L; Verhoef, Jan

2008-01-01

47

Complement-triggered pathways orchestrate regenerative responses throughout phylogenesis  

PubMed Central

Adult tissue plasticity, cell reprogramming, and organ regeneration are major challenges in the field of modern regenerative medicine. Devising strategies to increase the regenerative capacity of tissues holds great promise for dealing with donor organ shortages and low transplantation outcomes and also provides essential impetus to tissue bioengineering approaches for organ repair and replacement. The inherent ability of cells to reprogram their fate by switching into an embryonic-like, pluripotent progenitor state is an evolutionary vestige that in mammals has been retained mostly in fetal tissues and persists only in a few organs of the adult body. Tissue regeneration reflects the capacity of terminally differentiated cells to re-enter the cell cycle and proliferate in response to acute injury or environmental stress signals. In lower vertebrates, this regenerative capacity extends to several organs and remarkably culminates in precise tissue patterning, through cellular transdifferentiation and complex morphogenetic processes that can faithfully reconstruct entire body parts. Many lessons have been learned from robust regeneration models in amphibians such as the newt and axolotl. However, the dynamic interactions between the regenerating tissue, the surrounding stroma, and the host immune response, as it adapts to the actively proliferating tissue, remain ill-defined. The regenerating zone, through a sequence of distinct molecular events, adopts phenotypic plasticity and undergoes rigorous tissue remodeling that, in turn, evokes a significant inflammatory response. Complement is a primordial sentinel of the innate immune response that engages in multiple inflammatory cascades as it becomes activated during tissue injury and remodeling. In this respect, complement proteins have been implicated in tissue and organ regeneration in both urodeles and mammals. Distinct complement-triggered pathways have been shown to modulate critical responses that promote tissue reprogramming, pattern formation, and regeneration across phylogenesis. This article will discuss the mechanistic insights underlying the crosstalk of complement with cytokine and growth factor signaling pathways that drive tissue regeneration and will provide a unified conceptual framework for considering complement modulation as a novel target for regenerative therapeutics. PMID:23684626

Mastellos, Dimitrios C.; DeAngelis, Robert A.; Lambris, John D.

2014-01-01

48

Targeted Inhibition of the Complement Alternative Pathway with Complement Receptor 2 and Factor H Attenuates Collagen Antibody-Induced Arthritis in Mice  

PubMed Central

The alternative pathway (AP) of complement is required for the induction of collagen Ab-induced arthritis (CAIA) in mice. The objective of this study was to examine the effect of a recombinant AP inhibitor containing complement receptor 2 and factor H (CR2-fH) on CAIA in mice. CR2 binds to tissue-fixed activation fragments of C3, and the linked fH is a potent local inhibitor of the AP. CAIA was induced in C57BL/6 mice by i.p. injections of 4 mAb to type II collagen (CII) on day 0 and LPS on day 3. PBS or CR2-fH (250 or 500 ?g) were injected i.p. 15 min after the mAb to CII on day 0 and 15 min after LPS on day 3; the mice were sacrificed on day 10. The disease activity score (DAS) was decreased significantly (p < 0.001) in both groups receiving CR2-fH compared with the PBS. Histology scores for inflammation, pannus, bone damage, and cartilage damage decreased in parallel with the DAS. C3 deposition in the synovium and cartilage was significantly reduced (p < 0.0001) in the mice treated with CR2-fH. In vitro studies with immune complexes containing type II collagen and mAb to CII showed that CR2-fH specifically inhibited the AP with minimal effect on the classical pathway (CP) and no effect on the lectin pathway (LP). The relative potency of CR2-fH in vitro was superior to mAbs to factor B and C5. Thus, CR2-fH specifically targets and inhibits the AP of complement in vitro and is effective in CAIA in vivo. PMID:19828624

Banda, Nirmal K.; Levitt, Brandt; Glogowska, Magdalena J.; Thurman, Joshua M.; Takahashi, Kazue; Stahl, Gregory L.; Tomlinson, Stephen; Arend, William P.; Holers, V. Michael

2010-01-01

49

Characterization of mannose binding lectin from channel catfish Ictalurus punctatus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Mannose-binding lectin (MBL) is an important component of innate immunity capable of activating the lectin pathway of the complement system. A MBL gene was isolated from channel catfish (Ictalurus punctatus). The deduced protein contains a canonical collagen-like domain, a carbohydrate recognition d...

50

Regulation of the alternative pathway of complement modulates injury and immunity in a chronic model of dextran sulphate sodium-induced colitis.  

PubMed

The role of complement in inflammatory bowel disease (IBD) has been studied primarily using acute models, and it is unclear how complement affects processes in more relevant chronic models of IBD in which modulation of adaptive immunity and development of fibrosis have pathogenic roles. Using mice deficient in C1q/mannose-binding lectin (MBL) or C3, we demonstrated an important role for these opsonins and/or the classical pathway C3 convertase in providing protection against mucosal injury and infection in a model of chronic dextran sulphate sodium (DSS)-induced colitis. In contrast, deficiency of the alternative pathway (fB(-/-) mice) had significantly less impact on injury profiles. Consequently, the effect of a targeted inhibitor of the alternative pathway was investigated in a therapeutic protocol. Following the establishment of colitis, mice were treated with CR2-fH during subsequent periods of DSS treatment and acute injury (modelling relapse). CR2-fH significantly reduced complement activation, inflammation and injury in the colon, and additionally reduced fibrosis. Alternative pathway inhibition also altered the immune response in the chronic state in terms of reducing numbers of B cells, macrophages and mature dendritic cells in the lamina propria. This study indicates an important role for the alternative pathway of complement in the pathogenesis and the shaping of an immune response in chronic DSS-induced colitis, and supports further investigation into the use of targeted alternative pathway inhibition for the treatment of IBD. PMID:25293413

Elvington, M; Schepp-Berglind, J; Tomlinson, S

2015-03-01

51

Functional assessment of rat complement pathway activities and quantification of soluble C5b-9 in an experimental model of renal ischemia/reperfusion injury.  

PubMed

There is a growing interest in the monitoring of complement activation, not only in clinical settings but also in experimental models. However, for rodents only a limited number of tools are available to assess complement activity and activation. Here we describe three ELISAs for the measurement of rat classical (CP), MB-lectin (LP) and alternative (AP) pathway activities in serum and plasma. Moreover, we optimised a soluble C5b-9 (sC5b-9) ELISA for the detection of low level complement activation in rat. We determined the conditions for correct sample handling and showed that the assays had low inter- and intra-assay variation. We applied these assays to monitor complement activation in an experimental rat model of renal ischemia/reperfusion injury. We did not observe major complement consumption following reperfusion in CP or LP, and only minor AP consumption at 24h post reperfusion. However, MBL depletion prior to ischemia/reperfusion using a monoclonal antibody, transiently and specifically inhibited 75% of LP activity and ameliorated the AP consumption at 24h. To further assess complement activation during renal IRI, we monitored serum sC5b-9 and found that it was only significantly increased 72h post-reperfusion, but not when rats were pre-treated with anti-MBL or after sham surgery. In conclusion the described assays enable sensitive, reproducible and comprehensive assessment of complement activation in experimental rat models. PMID:24953215

Kotimaa, J; van der Pol, P; Leijtens, S; Klar-Mohammad, N; Schilders, G; Daha, M R; Rutjes, H; van Kooten, C

2014-10-01

52

Complement activation in experimental human malaria infection.  

PubMed

The objective of this study was to investigate complement activation in uncomplicated, early phases of human malaria. Fifteen healthy volunteers were experimentally infected with Plasmodium falciparum malaria. Parasitemia and complement activation products were assessed. During blood stage parasitemia, volunteers showed a significant increase in soluble terminal complement complex (TCC) formation. After start of a curative regimen of artemether/lumefantrine, TCC further increased due to activation of both the classical and the alternative pathway. In-vitro studies confirmed activation of complement by parasite cultures. We thus detected an increase in complement activation in volunteers with experimentally induced malaria, even before parasitemia could be detected microscopically. This significant increase in complement activation occurred despite the possible control of TCC formation by complement regulatory proteins on erythrocytes and the extremely low levels of parasitemia. Treatment with artemether/lumefantrine was followed by classical and alternative pathway complement activation, without evidence for mannan-binding-lectin-mediated complement activation. PMID:17481680

Roestenberg, Meta; McCall, Matthew; Mollnes, Tom Eirik; van Deuren, Marcel; Sprong, Tom; Klasen, Ina; Hermsen, Cornelus C; Sauerwein, Robert W; van der Ven, André

2007-07-01

53

Blockade of Alternative Complement Pathway in Dense Deposit Disease  

PubMed Central

A patient aged 17 with dense deposit disease associated with complement activation, circulating C3 Nef, and Factor H mutation presented with nephrotic syndrome and hypertension. Steroid therapy, plasma exchange, and rituximab failed to improve proteinuria and hypertension despite a normalization of the circulating sC5b9 complex. Eculizumab, a monoclonal antibody directed against C5, was used to block the terminal product of the complement cascade. The dose was adapted to achieve a CH50 below 10%, but proteinuria and blood pressure were not improved after 3 months of treatment. PMID:24672732

Sacquépée, Mathieu; Fila, Marc; Peuchmaur, Michel; Perrier-Cornet, Emilia; Frémeaux-Bacchi, Véronique; Deschęnes, Georges

2014-01-01

54

Clinical hypothermia temperatures increase complement activation and cell destruction via the classical pathway  

PubMed Central

Background Therapeutic hypothermia is a treatment modality that is increasingly used to improve clinical neurological outcomes for ischemia-reperfusion injury-mediated diseases. Antibody-initiated classical complement pathway activation has been shown to contribute to ischemia-reperfusion injury in multiple disease processes. However, how therapeutic hypothermia affects complement activation is unknown. Our goal was to measure the independent effect of temperature on complement activation, and more specifically, examine the relationship between clinical hypothermia temperatures (31–33°C), and complement activation. Methods Antibody-sensitized erythrocytes were used to assay complement activation at temperatures ranging from 0-41°C. Individual complement pathway components were assayed by ELISA, Western blot, and quantitative dot blot. Peptide Inhibitor of complement C1 (PIC1) was used to specifically inhibit activation of C1. Results Antibody-initiated complement activation resulting in eukaryotic cell lysis was increased by 2-fold at 31°C compared with 37°C. Antibody-initiated complement activation in human serum increased as temperature decreased from 37°C until dramatically decreasing at 13°C. Quantitation of individual complement components showed significantly increased activation of C4, C3, and C5 at clinical hypothermia temperatures. In contrast, C1s activation by heat-aggregated IgG decreased at therapeutic hypothermia temperatures consistent with decreased enzymatic activity at lower temperatures. However, C1q binding to antibody-coated erythrocytes increased at lower temperatures, suggesting that increased classical complement pathway activation is mediated by increased C1 binding at therapeutic hypothermia temperatures. PIC1 inhibited hypothermia-enhanced complement-mediated cell lysis at 31°C by up to 60% (P?=?0.001) in a dose dependent manner. Conclusions In summary, therapeutic hypothermia temperatures increased antibody-initiated complement activation and eukaryotic cell destruction suggesting that the benefits of therapeutic hypothermia may be mediated via other mechanisms. Antibody-initiated complement activation has been shown to contribute to ischemia-reperfusion injury in several animal models, suggesting that for diseases with this mechanism hypothermia-enhanced complement activation may partially attenuate the benefits of therapeutic hypothermia. PMID:24962100

2014-01-01

55

The complement system in human cardiometabolic disease.  

PubMed

The complement system has been implicated in obesity, fatty liver, diabetes and cardiovascular disease (CVD). Complement factors are produced in adipose tissue and appear to be involved in adipose tissue metabolism and local inflammation. Thereby complement links adipose tissue inflammation to systemic metabolic derangements, such as low-grade inflammation, insulin resistance and dyslipidaemia. Furthermore, complement has been implicated in pathophysiological mechanisms of diet- and alcohol induced liver damage, hyperglycaemia, endothelial dysfunction, atherosclerosis and fibrinolysis. In this review, we summarize current evidence on the role of the complement system in several processes of human cardiometabolic disease. C3 is the central component in complement activation, and has most widely been studied in humans. C3 concentrations are associated with insulin resistance, liver dysfunction, risk of the metabolic syndrome, type 2 diabetes and CVD. C3 can be activated by the classical, the lectin and the alternative pathway of complement activation; and downstream activation of C3 activates the terminal pathway. Complement may also be activated via extrinsic proteases of the coagulation, fibrinolysis and the kinin systems. Studies on the different complement activation pathways in human cardiometabolic disease are limited, but available evidence suggests that they may have distinct roles in processes underlying cardiometabolic disease. The lectin pathway appeared beneficial in some studies on type 2 diabetes and CVD, while factors of the classical and the alternative pathway were related to unfavourable cardiometabolic traits. The terminal complement pathway was also implicated in insulin resistance and liver disease, and appears to have a prominent role in acute and advanced CVD. The available human data suggest a complex and potentially causal role for the complement system in human cardiometabolic disease. Further, preferably longitudinal studies are needed to disentangle which aspects of the complement system and complement activation affect the different processes in human cardiometabolic disease. PMID:25017306

Hertle, E; Stehouwer, C D A; van Greevenbroek, M M J

2014-10-01

56

Alternative Complement Pathway Deficiency Ameliorates Chronic Smoke-Induced Functional and Morphological Ocular Injury  

PubMed Central

Background Age-related macular degeneration (AMD), a complex disease involving genetic variants and environmental insults, is among the leading causes of blindness in Western populations. Genetic and histologic evidence implicate the complement system in AMD pathogenesis; and smoking is the major environmental risk factor associated with increased disease risk. Although previous studies have demonstrated that cigarette smoke exposure (CE) causes retinal pigment epithelium (RPE) defects in mice, and smoking leads to complement activation in patients, it is unknown whether complement activation is causative in the development of CE pathology; and if so, which complement pathway is required. Methods Mice were exposed to cigarette smoke or clean, filtered air for 6 months. The effects of CE were analyzed in wildtype (WT) mice or mice without a functional complement alternative pathway (AP; CFB?/?) using molecular, histological, electrophysiological, and behavioral outcomes. Results CE in WT mice exhibited a significant reduction in function of both rods and cones as determined by electroretinography and contrast sensitivity measurements, concomitant with a thinning of the nuclear layers as measured by SD-OCT imaging and histology. Gene expression analyses suggested that alterations in both photoreceptors and RPE/choroid might contribute to the observed loss of function, and visualization of complement C3d deposition implies the RPE/Bruch's membrane (BrM) complex as the target of AP activity. RPE/BrM alterations include an increase in mitochondrial size concomitant with an apical shift in mitochondrial distribution within the RPE and a thickening of BrM. CFB?/? mice were protected from developing these CE-mediated alterations. Conclusions Taken together, these findings provide clear evidence that ocular pathology generated in CE mice is dependent on complement activation and requires the AP. Identifying animal models with RPE/BrM damage and verifying which aspects of pathology are dependent upon complement activation is essential for developing novel complement-based treatment approaches for the treatment of AMD. PMID:23825688

Woodell, Alex; Coughlin, Beth; Kunchithapautham, Kannan; Casey, Sarah; Williamson, Tucker; Ferrell, W. Drew; Atkinson, Carl; Jones, Bryan W.; Rohrer, Bärbel

2013-01-01

57

Preferential activation and depletion of the alternative complement pathway by burn injury.  

PubMed

Complement levels of eight adult burn patients (25% to 90% body surface area) were studied upon admission to a burn unit and sequentially for one week. Mean classical pathway titers (CH50) were 49% below the normal mean, while hemolytic C4 titers were reduced by 53% and C3 by 43%. However, the alternative pathway titer was reduced by more than 90%, suggesting preferential depletion of this pathway. This depletion was associated with sepsis, pneumonia, and "shock lung." Alternative pathway deficiency was still present one week postburn, and may contribute to the susceptibility of burn patients to bacterial sepsis. PMID:6859992

Gelfand, J A; Donelan, M; Burke, J F

1983-07-01

58

Complement activation by salivary agglutinin is secretor status dependent.  

PubMed

After mucosal damage or gingival inflammation, complement proteins leak into the oral cavity and mix with salivary proteins such as salivary agglutinin (SAG/gp-340/DMBT1). This protein is encoded by the gene Deleted in Malignant Brain Tumors 1 (DMBT1), and it aggregates bacteria, viruses and fungi, and activates the lectin pathway of the complement system. In the lectin pathway, carbohydrate structures on pathogens or altered self cells are recognized. SAG is highly glycosylated, partly on the basis of the donor's blood group status. Whereas secretors express Lewis b, Lewis y, and antigens from the ABO-blood group system on SAG, non-secretors do not. Through mannose-binding lectin (MBL) binding and C4 deposition assays, we aimed to identify the chemical structures on SAG that are responsible for complement activation. The complement-activating properties of SAG were completely abolished by oxidation of its carbohydrate moiety. SAG-mediated activation of complement was also inhibited in the presence of saccharides such as fucose and Lewis b carbohydrates, and also after pretreatment with the fucose-binding lectin, Anguilla anguilla agglutinin. Complement activation was significantly (p<0.01) higher in secretors than in non-secretors. Our results suggest that fucose-rich oligosaccharide sidechains, such as Lewis b antigens, are involved in the activation of complement by SAG. PMID:25153235

Gunput, Sabrina T G; Ligtenberg, Antoon J M; Terlouw, Bas; Brouwer, Mieke; Veerman, Enno C I; Wouters, Diana

2015-01-01

59

Low activity of the classical complement pathway predicts short survival of patients with chronic lymphocytic leukaemia.  

PubMed Central

The activities of the classical (CP) and alternative (AP) complement pathways as well as the levels of some complement components and circulating immune complexes were measured in 43 patients with chronic lymphocytic leukaemia (CLL) between 1980 and 1984. Depressed CP activities were frequently found in these patients. Clinical course of the disease in the patients was followed until 1992, and compared with the initial complement values. During the follow-up period 36 patients died, death of 33 patients being related to the underlying disease. A strong positive correlation (P < 0.01) was found between the length of survival of the patients and the initial CP values. Patients were divided into two groups: group A, short-term survivors, i.e patients who died in CLL-related complications within 3 years after the complement measurements; and group B, long-term survivors who died > or = 4 years after the complement measurements due to any cause, or were alive at the end of the follow-up period. Average CP values in Group B were almost twice those in group A (P = 0.002), and a similar but less pronounced difference was found in C3 levels (P = 0.055). These differences were even more marked (P = 0.0006 and P = 0.0015, respectively) when only patients in Rai stage 2 and 3 were considered. Low classical pathway activities predicted short survival time: according to the logrank test, patients in Rai stage 2-3 with low (< mean - 2s.d. of the normal values), and normal CP levels survived for 2.0 +/- 1.1, and 4.6 +/- 3.0 years, respectively. All the nine and 11/13 patients with low CP and C4 levels, respectively, died within 3 years after the complement measurements were made. These findings indicate that complement measurements performed in CLL patients have a clinical value. PMID:7813102

Varga, L; Czink, E; Miszlai, Z; Pálóczi, K; Bányai, A; Szegedi, G; Füst, G

1995-01-01

60

Complement activation by the alternative pathway and macrophage enzyme secretion in the pathogenesis of chronic inflammation.  

PubMed Central

A number of stimuli known to induce acid hydrolase secretion from cultured macrophages were examined for their ability to activate C3 via the alternative pathway of the complement system. Loss of haemolytically active C3 was checked in normal and C4-deficient guinea-pig serum. For comparison the interactions of cultured macrophages with other agents well known as potent activators of the alternative pathway of the complement system have been investigated. As judged by their activity in these assays, group A streptococcal cell walls, different carrageenan preparations, dental plaque and Actinomyces viscosus were all capable of initiating the alternative pathway but differed with respect to their potency and their ability to inhibit C3 turnover at high concentrations. Zymosan, some carrageenans, polyanethol sulphonate, and Corynebacterium parvum all induce the release of hydrolytic enzymes from macrophages in culture, even in the absence of serum in the medium. The release is time- and dose-dependent and is not associated with loss of the cytoplasmic enzyme lactate dehydrogenase or any other sign of cell death. The parallelism between the capacity of several agents to activate the complement system via the alternative pathway and to induce inflammatory responses in vivo and selective lysosoma enzyme secretion from cultures of macrophages is discussed. PMID:328387

Schorlemmer, H U; Bitter-Suermann, D; Allison, A C

1977-01-01

61

The role of complement in membranous nephropathy  

PubMed Central

Membranous nephropathy (MN) describes a histopathological pattern of injury marked by glomerular subepithelial immune deposits and collectively represents one of the most common causes of adult nephrotic syndrome. Studies in Heymann nephritis, an experimental model of MN, have established a paradigm in which these deposits locally activate complement to cause podocyte injury, culminating in cytoskeletal reorganization, loss of slit diaphragms, and proteinuria. There is much circumstantial evidence for a prominent role of complement in human MN, as C3 and C5b-9 are consistently found within immune deposits. Secondary MN often exhibits the additional presence of C1q, implicating the classical pathway of complement activation. Primary MN, however, is IgG4-predominant and IgG4 is considered incapable of binding C1q and activating the complement pathway. Recent studies have identified the M-type phospholipase A2 receptor (PLA2R) as the major target antigen in primary MN. Early evidence hints that IgG4 anti-PLA2R autoantibodies can bind mannan-binding lectin and activate the lectin complement pathway. The identification of anti-PLA2R antibodies as likely participants in the pathogenesis of disease will allow focused investigation into the role of complement in MN. Definitive therapy for MN is immunosuppression, although future therapeutic agents that specifically target complement activation may represent an effective temporizing measure to forestall further glomerular injury. PMID:24161038

Ma, Hong; Sandor, Dana G.; Beck, Laurence H.

2013-01-01

62

Experimental murine acid aspiration injury is mediated by neutrophils and the alternative complement pathway  

Microsoft Academic Search

mental murine acid aspiration injury is mediated by neutro- phils and the alternative complement pathway. J. Appl. Physiol. 83(4): 1090-1095, 1997.—Acid aspiration may result in the development of the acute respiratory distress syn- drome, an event associated with significant morbidity and mortality. Although once attributed to direct distal airway injury, the pulmonary failure after acid aspiration is more complex and

MARTIN R. WEISER; TAINE T. V. PECHET; JULIAN P. WILLIAMS; MINGHE MA; PAUL S. FRENETTE; FRANCIS D. MOORE; LESTER KOBZIK; RICHARD O. HINES; DENISA D. WAGNER; MICHAEL C. CARROLL; HERBERT B. HECHTMAN; Julian P. Wil

63

Properdin and Factor H: Opposing Players on the Alternative Complement Pathway “See-Saw”  

PubMed Central

Properdin and factor H are two key regulatory proteins having opposite functions in the alternative complement pathway. Properdin up-regulates the alternative pathway by stabilizing the C3bBb complex, whereas factor H downregulates the pathway by promoting proteolytic degradation of C3b. While factor H is mainly produced in the liver, there are several extrahepatic sources. In addition to the liver, factor H is also synthesized in fetal tubuli, keratinocytes, skin fibroblasts, ocular tissue, adipose tissue, brain, lungs, heart, spleen, pancreas, kidney, muscle, and placenta. Neutrophils are the major source of properdin, and it is also produced by monocytes, T cells and bone marrow progenitor cell line. Properdin is released by neutrophils from intracellular stores following stimulation by N-formyl-methionine-leucine-phenylalanine (fMLP) and tumor necrosis factor alpha (TNF-?). The HEP G2 cells derived from human liver has been found to produce functional properdin. Endothelial cells also produce properdin when induced by shear stress, thus is a physiological source for plasma properdin. The diverse range of extrahepatic sites for synthesis of these two complement regulators suggests the importance and need for local availability of the proteins. Here, we discuss the significance of the local synthesis of properdin and factor H. This assumes greater importance in view of recently identified unexpected and novel roles of properdin and factor H that are potentially independent of their involvement in complement regulation. PMID:23630525

Kouser, Lubna; Abdul-Aziz, Munirah; Nayak, Annapurna; Stover, Cordula M.; Sim, Robert B.; Kishore, Uday

2013-01-01

64

Study of the optimal reaction conditions for assay of the mouse alternative complement pathway.  

PubMed

The optimal reaction conditions for hemolytic assay of alternative complement pathway activity in mouse serum were investigated. A microtiter system was used, in which a number of 7.5 X 10(6) rabbit erythrocytes per test well appeared to be optimal. Rabbit erythrocytes were superior as target cells over erythrocytes from a number of other animal species. The optimal conditions were as follows: an incubation temperature of 39 degrees C, an ionic strength of about 200 mM, and a magnesium concentration of 2.5 mM. Incubation during 60 min was not sufficient for an end-point titration. Addition of 1 mg of zymosan A per test well, however, enhanced and accelerated the hemolytic activity of mouse serum via the alternative pathway resulting in a maximum value after 45 min. This, most probably, proceeded by a mechanism involving the formation of a zymosan-C5-convertase and bystander lysis of the target cells. In contrast to the normal alternative pathway assay the zymosan-potentiated test did, most probably, not involve natural antibodies. Cobra venom factor was more efficient in enhancing the sensitivity of the assay for the mouse alternative complement pathway than zymosan. This makes this factor very useful for testing C-poor body fluids. PMID:4078314

Van Dijk, H; Rademaker, P M; Klerx, J P; Willers, J M

1985-12-27

65

Exogenous expression of marine lectins DlFBL and SpRBL induces cancer cell apoptosis possibly through PRMT5-E2F-1 pathway  

PubMed Central

Lectins are widely existed in marine bioresources, and some purified marine lectins were found toxic to cancer cells. In this report, genes encoding Dicentrarchus labrax fucose-binding lectin (DlFBL) and Strongylocentrotus purpuratus rhamnose-binding lectin (SpRBL) were inserted into an adenovirus vector to form Ad.FLAG-DlFBL and Ad.FLAG-SpRBL, which elicited significant in vitro suppressive effect on a variety of cancer cells. Anti-apoptosis factors Bcl-2 and XIAP were determined to be downregulated by Ad.FLAG-DlFBL and Ad.FLAG-SpRBL. Subcellular localization studies showed that DlFBL but not SpRBL widely distributed in membrane systems. Both DlFBL and SpRBL were shown associated with protein arginine methyltransferase 5 (PRMT5), and PRMT5-E2F-1 pathway was suggested to be responsible for the DlFBL and SpRBL induced apoptosis. Further investigations revealed that PRMT5 acted as a common binding target for various exogenous lectin and non-lectin proteins, suggesting a role of PRMT5 as a barrier for foreign gene invasion. The cellular response to exogenous lectins may provide insights into a novel way for cancer gene therapy. PMID:24675921

Wu, Liqin; Yang, Xinyan; Duan, Xuemei; Cui, Lianzhen; Li, Gongchu

2014-01-01

66

Mushroom lectins  

Microsoft Academic Search

Many plants, animals, and microorganisms contain lectins, but relatively few studies have been conducted on lectins from mushrooms. Some lectins have been isolated from the fruiting bodies of Basidio?mycetes fungi. Among the species studied are: Ischchnoderma res?inosum lectin (IRA), Grifola fondosa lectin (GFL), Forties fomen?tarius lectin (FFL), Ganoderma lucidum lectin (GLL), etc. Some properties of these lectins are presented in

Hirokazu KaWagishi

1995-01-01

67

Alternative complement pathway component Factor D contributes to efficient clearance of tissue debris following acute CCl?-induced injury.  

PubMed

Complement, part of the innate immune system, is involved with immune protection against invading pathogens as well as cell survival and tissue regeneration. It is known that complement activation is required for timely hepatocyte recovery following an acute toxic injury, but which pathway of complement activation is involved in response to hepatocyte injury has not been identified. In these studies we utilize mice deficient in C1qa, C4 and Factor D, lacking the classical, classical/MBL, and alternative pathways of complement activation, respectively, to identify an essential role for Factor D in the ability of the liver to recover from acute toxic injury. Here we demonstrate that following an acute CCl4-induced injury, the involvement of the alternative complement pathway is essential for efficient liver recovery. PMID:25467802

Cresci, Gail A; Allende, Daniela; McMullen, Megan R; Nagy, Laura E

2015-03-01

68

Edwardsiella tarda evades serum killing by preventing complement activation via the alternative pathway.  

PubMed

Edwardsiella tarda is a Gram-negative bacterium with a broad host range that includes a wide variety of farmed fish as well as humans. E. tarda has long been known to be able to survive in host serum, but the relevant mechanism is unclear. In this study, we investigated the fundamental question, i.e. whether E. tarda activated serum complement or not. We found that (i) when incubated with flounder serum, E. tarda exhibited a high survival rate (87.6%), which was slightly but significantly reduced in the presence of Mg(2+); (ii) E. tarda-incubated serum possessed strong hemolytic activity and bactericidal activity, (iii) compared to the serum incubated with a complement-sensitive laboratory Escherichia coli strain, E. tarda-incubated serum exhibited much less chemotactic activity, (iv) in contrast to the serum incubated with live E. tarda, the serum incubated with heat-inactivated E. tarda exhibited no apparent hemolytic capacity. Taken together, these results indicate for the first time that E. tarda circumvents serum attack by preventing, to a large extent, complement activation via the alternative pathway, and that heat-labile surface structures likely play an essential role in the complement evasion of E. tarda. PMID:25575477

Li, Mo-Fei; Sun, Li; Li, Jun

2015-04-01

69

Isolated compounds from black bean inhibit the classical pathway of the complement.  

PubMed

The present study evaluated the anticomplement effects from isolated compounds of black bean in classical pathway complement system. Using column chromatograph, four compounds kaempferol 3-O-?-D-glucopyranoside (1), kaempferol 5-O-?-D-glucopyranoside (2), 3-O-[?-L-rhamnopyranosyl(1-2)-?-D-glucopyranosyl(1-2)-?-D-glucuronopyranosyl]olean-12-en-3?,22?,24-triol (3) and 3-O-[?-D-glucopyranosyl(1-2)-?-D-galactopyranosyl(1-2)-?-D-glucuronopyranosyl]olean-12-en-3?,22?,24-triol (4) were isolated and evaluated for in vitro anticomplement activity. 3 showed inhibitory activity against complement system with 50% inhibitory concentrations (IC(50)) values of 98.2 ?g/ml. This is the first report of anticomplement activity of isolated compounds from black bean. PMID:22121891

Moon, Hyung-In; Kim, Kyoung-Sook; Lee, Young-Choon; Lee, Jai-Heon

2011-11-29

70

Activation of the alternative pathway of complement by monosodium urate monohydrate crystals and other inflammatory particles.  

PubMed Central

Activation of serum C3 by monosodium urate monohydrate (MSU) crystals and other particles was determined by immunofixation following electrophoretic separation of C3 and its activation products. Densitometry allowed quantitation of results. MSU, hydroxyapatite, brushite, and calcium pyrophosphate dihydrate crystals split C3 under conditions which demonstrate activation via the alternative pathway (AP). Quantitatively similar results were obtained in immunoglobulin deficient serum. Activation was crystal specific and was reduced by heating, grinding, sonication, and aging of crystals. Other inflammatory particles (e.g., blackthorn) activated C3 via the AP: noninflammatory particles (e.g., diamond) caused insignificant activation. It is suggested that particle-induced activation of the alternative pathway of complement may be important in the initiation of crystal-induced synovitis. Images PMID:6407405

Doherty, M; Whicher, J T; Dieppe, P A

1983-01-01

71

Complement alternative pathway genetic variation and Dengue infection in the Thai population  

PubMed Central

Dengue disease is a mosquito-borne infection caused by Dengue virus. Infection may be asymptomatic or variably manifest as mild Dengue fever (DF) to the most severe form, Dengue haemorrhagic fever (DHF). Mechanisms that influence disease severity are not understood. Complement, an integral component of the immune system, is activated during Dengue infection and the degree of activation increases with disease severity. Activation of the complement alternative pathway is influenced by polymorphisms within activation (factor B rs12614/rs641153, C3 rs2230199) and regulatory [complement factor H (CFH) rs800292] proteins, collectively termed a complotype. Here, we tested the hypothesis that the complotype influences disease severity during secondary Dengue infection. In addition to the complotype, we also assessed two other disease-associated CFH polymorphisms (rs1061170, rs3753394) and a structural polymorphism within the CFH protein family. We did not detect any significant association between the examined polymorphisms and Dengue infection severity in the Thai population. However, the minor allele frequencies of the factor B and C3 polymorphisms were less than 10%, so our study was not sufficiently powered to detect an association at these loci. We were also unable to detect a direct interaction between CFH and Dengue NS1 using both recombinant NS1 and DV2-infected culture supernatants. We conclude that the complotype does not influence secondary Dengue infection severity in the Thai population. PMID:23919682

Kraivong, R; Vasanawathana, S; Limpitikul, W; Malasit, P; Tangthawornchaikul, N; Botto, M; Screaton, G R; Mongkolsapaya, J; Pickering, M C

2013-01-01

72

Complement in animal development: Unexpected roles of a highly conserved pathway  

PubMed Central

The complement pathway is most famous for its role in immunity, orchestrating an exquisitely refined system for immune surveillance. At its core lies a cascade of proteolytic events that ultimately serve to recognise microbes, infected cells or debris and target them for elimination. Mounting evidence has shown that a number of the proteolytic intermediaries in this cascade have, in themselves, other functions in the body, signalling through receptors to drive events that appear to be unrelated to immune surveillance. It seems, then, that the complement system not only functions as an immunological effector, but also has cell–cell signalling properties that are utilised by a number of non-immunological processes. In this review we examine a number of these processes in the context of animal development, all of which share a requirement for precise control of cell behaviour in time and space. As we will see, the scope of the complement system's function is indeed much greater than we might have imagined only a few years ago. PMID:23665279

Leslie, Jonathan D.; Mayor, Roberto

2013-01-01

73

The mannose-binding lectin pathway is a significant contributor to reperfusion injury in the type 2 diabetic heart.  

PubMed

The severity of ischaemic heart disease is markedly enhanced in type 2 diabetes. We recently reported that complement activation exacerbates I/R injury in the type 2 diabetic heart. The purpose of this study was to isolate and examine MBL pathway activation following I/R injury in the diabetic heart. ZLC and ZDF rats underwent 30 minutes of left coronary artery occlusion followed by 120 minutes of reperfusion. Two different groups of ZDF rats were treated with either FUT-175, a broad complement inhibitor, or P2D5, a monoclonal antibody raised against rat MBL-A. ZDF rats treated with FUT175 and P2D5 had significantly decreased myocardial infarct size, C3 deposition and neutrophil accumulation compared with untreated ZDF controls. Taken together, these findings indicate that the MBL pathway plays a key role in the severity of complement-mediated I/R injury in the type 2 diabetic heart. PMID:20216929

La Bonte, Laura R; Dokken, Betsy; Davis-Gorman, Grace; Stahl, Gregory L; McDonagh, Paul F

2009-07-01

74

Complement alternative pathway activation in the course of thrombotic microangiopathy associated with adult-onset Still's disease.  

PubMed

Atypical haemolytic uraemic syndrome is a rare disease associated which genetic or acquired factors those cause defective regulation of the alternative complement pathway. We report the case of a 46-year-old woman who presented with thrombotic microangiopathy coinciding with a monocyclic evolution of adult-onset Still's disease. Low C3 with decreased FB concentration, associated with normal C4 was present until the thrombotic microangiopathy's resolution, indicative of an excessive production of alternative C3 convertase. She responded to plasma exchange. This observation reinforces the hypothesis for a common pathway in the pathogenesis for both of the diseases, and suggests alternative complement pathway mediation. PMID:23562215

Carron, Pierre-Louis; Cartier, Jean-Charles; Truche, Anne-Sophie; Brunelle, Charlotte; Cartier, Julien; Malvezzi, Paolo; Ponard, Denise

2013-12-01

75

Complement regulators in human disease: lessons from modern genetics.  

PubMed

First identified in human serum in the late 19th century as a 'complement' to antibodies in mediating bacterial lysis, the complement system emerged more than a billion years ago probably as the first humoral immune system. The contemporary complement system consists of nearly 60 proteins in three activation pathways (classical, alternative and lectin) and a terminal cytolytic pathway common to all. Modern molecular biology and genetics have not only led to further elucidation of the structure of complement system components, but have also revealed function-altering rare variants and common polymorphisms, particularly in regulators of the alternative pathway, that predispose to human disease by creating 'hyperinflammatory complement phenotypes'. To treat these 'complementopathies', a monoclonal antibody against the initiator of the membrane attack complex, C5, has received approval for use. Additional therapeutic reagents are on the horizon. PMID:25495259

K Liszewski, M; Atkinson, J P

2015-03-01

76

A Novel Targeted Inhibitor of the Alternative Pathway of Complement and Its Therapeutic Application in Ischemia/Reperfusion Injury1  

PubMed Central

Bioavailability and therapeutic efficacy of soluble Crry, a mouse inhibitor of all complement activation pathways, is significantly enhanced when linked to a fragment of complement receptor 2 (CR2), a receptor that targets C3 activation products. In this study, we characterize alternative pathway-specific inhibitors consisting of a single or dimeric N-terminal region of mouse factor H (fH; short consensus repeats 1–5) linked to the same CR2 fragment (CR2-fH and CR2-fHfH). Both CR2-fH and CR2-fHfH were highly effective at inhibiting the alternative pathway in vitro and demonstrated a higher specific activity than CR2-Crry. CR2-fH was also more effective than endogenous serum fH in blocking target deposition of C3. Target binding and complement inhibitory activity of CR2-fH/CR2-fHfH was dependent on CR2- and C3-mediated interactions. The alternative pathway of complement plays a role in intestine ischemia/reperfusion injury. However, serum fH fails to provide protection against intestine ischemia/reperfusion injury although it can bind to and provide cell surfaces with protection from complement and is present in plasma at a high concentration. In a mouse model, CR2-fH and CR2-fHfH provided complete protection from local (intestine) and remote (lung) injury. CR2-fH targeted to the site of local injury and greatly reduced levels of tissue C3 deposition. Thus, the targeting mechanism significantly enhances alternative pathway-specific complement inhibitory activity of the N-terminal domain of fH and has the potential to reduce side effects that may be associated with systemic complement blockade. The data further indicate alternative pathway dependence for local and remote injury following intestinal ischemia/reperfusion in a clinically relevant therapeutic paradigm. PMID:19017999

Huang, Yuxiang; Qiao, Fei; Atkinson, Carl; Holers, V. Michael; Tomlinson, Stephen

2009-01-01

77

Floridoside Extracted from the Red Alga Mastocarpus stellatus Is a Potent Activator of the Classical Complement Pathway  

PubMed Central

Many biological properties of algae have been found to have useful applications in human health, particularly in the fields of oncology and immunology. Floridoside, extracted from the red alga Mastocarpus stellatus, has a structure similar to the xenoantigen Gal alpha 1–3 Gal. This xenoantigen has been described to induce a high immune response in human xenografts and is mediated by natural anti-gal antibodies that activate the classical complement pathway. Based on this property, we analyzed the potential activities of floridoside on the immune system. We demonstrated that floridoside activates a complement cascade via the classical complement pathway, through the recruitment and activation of natural IgM. This algal molecule could represent an important step in the development of a potent new anticomplementary agent for use in therapeutic complement depletion. PMID:19005576

Courtois, Anthony; Simon-Colin, Christelle; Boisset, Claire; Berthou, Christian; Deslandes, Eric; Guézennec, Jean; Bordron, Anne

2008-01-01

78

Floridoside extracted from the red alga Mastocarpus stellatus is a potent activator of the classical complement pathway.  

PubMed

Many biological properties of algae have been found to have useful applications in human health, particularly in the fields of oncology and immunology. Floridoside, extracted from the red alga Mastocarpus stellatus, has a structure similar to the xenoantigen Gal alpha 1-3 Gal. This xenoantigen has been described to induce a high immune response in human xenografts and is mediated by natural anti-gal antibodies that activate the classical complement pathway. Based on this property, we analyzed the potential activities of floridoside on the immune system. We demonstrated that floridoside activates a complement cascade via the classical complement pathway, through the recruitment and activation of natural IgM. This algal molecule could represent an important step in the development of a potent new anticomplementary agent for use in therapeutic complement depletion. PMID:19005576

Courtois, Anthony; Simon-Colin, Christelle; Boisset, Claire; Berthou, Christian; Deslandes, Eric; Guézennec, Jean; Bordron, Anne

2008-01-01

79

Alternative complement pathway and factor B activities in rats with altered blood levels of thyroid hormone  

PubMed Central

Evaluating the activity of the complement system under conditions of altered thyroid hormone levels might help elucidate the role of complement in triggering autoimmune processes. Here, we investigated alternative pathway (AP) activity in male Wistar rats (180 ± 10?g) after altering their thyroid hormone levels by treatment with triiodothyronine (T3), propylthiouracil (PTU) or thyroidectomy. T3 and thyroxine (T4) levels were determined by chemiluminescence assays. Hemolytic assays were performed to evaluate the lytic activity of the AP. Factor B activity was evaluated using factor B-deficient serum. An anti-human factor B antibody was used to measure factor B levels in serum by radial immunodiffusion. T3 measurements in thyroidectomized animals or animals treated with PTU demonstrated a significant reduction in hormone levels compared to control. The results showed a reduction in AP lytic activity in rats treated with increasing amounts of T3 (1, 10, or 50?µg). Factor B activity was also decreased in the sera of hyperthyroid rats treated with 1 to 50?µg T3. Additionally, treating rats with 25?µg T3 significantly increased factor B levels in their sera (P < 0.01). In contrast, increased factor B concentration and activity (32%) were observed in hypothyroid rats. We conclude that alterations in thyroid hormone levels affect the activity of the AP and factor B, which may in turn affect the roles of AP and factor B in antibody production. PMID:22370704

Bitencourt, C.S.; Duarte, C.G.; Azzolini, A.E.C.S.; Assis-Pandochi, A.I.

2012-01-01

80

Alternative complement pathway and factor B activities in rats with altered blood levels of thyroid hormone.  

PubMed

Evaluating the activity of the complement system under conditions of altered thyroid hormone levels might help elucidate the role of complement in triggering autoimmune processes. Here, we investigated alternative pathway (AP) activity in male Wistar rats (180 ± 10 g) after altering their thyroid hormone levels by treatment with triiodothyronine (T3), propylthiouracil (PTU) or thyroidectomy. T3 and thyroxine (T4) levels were determined by chemiluminescence assays. Hemolytic assays were performed to evaluate the lytic activity of the AP. Factor B activity was evaluated using factor B-deficient serum. An anti-human factor B antibody was used to measure factor B levels in serum by radial immunodiffusion. T3 measurements in thyroidectomized animals or animals treated with PTU demonstrated a significant reduction in hormone levels compared to control. The results showed a reduction in AP lytic activity in rats treated with increasing amounts of T3 (1, 10, or 50 µg). Factor B activity was also decreased in the sera of hyperthyroid rats treated with 1 to 50 µg T3. Additionally, treating rats with 25 µg T3 significantly increased factor B levels in their sera (P < 0.01). In contrast, increased factor B concentration and activity (32%) were observed in hypothyroid rats. We conclude that alterations in thyroid hormone levels affect the activity of the AP and factor B, which may in turn affect the roles of AP and factor B in antibody production. PMID:22370704

Bitencourt, C S; Duarte, C G; Azzolini, A E C S; Assis-Pandochi, A I

2012-03-01

81

Glycosylation of IgA is required for optimal activation of the alternative complement pathway by immune complexes.  

PubMed Central

To investigate the effect of carbohydrate on activation of the alternative pathway of complement by IgA immune complexes, aglycosylated monoclonal IgA was made biosynthetically in the presence of tunicamycin. When immune complexes were incubated with normal human serum (NHS), the aglycosylated IgA immune complexes caused less depletion of the alternative pathway activity of the serum. They also bound less C3 and produced less terminal complement complexes. The binding of C3 to both immune complexes was mainly through hydroxylamine sensitive ester bonds. C3 did not bind to free IgA. Images Figure 1 Figure 5 Figure 6 PMID:8132210

Zhang, W; Lachmann, P J

1994-01-01

82

Deficiency in Mannose-Binding Lectin-Associated Serine Protease-2 Does Not Increase Susceptibility to Trypanosoma cruzi Infection.  

PubMed

Trypanosoma cruzi is the causative agent of Chagas' disease, a chronic illness affecting 10 million people around the world. The complement system plays an important role in fighting microbial infections. The recognition molecules of the lectin pathway of complement activation, mannose-binding lectin (MBL), ficolins, and CL-11, bind to specific carbohydrates on pathogens, triggering complement activation through MBL-associated serine protease-2 (MASP-2). Previous in vitro work showed that human MBL and ficolins contribute to T. cruzi lysis. However, MBL-deficient mice are only moderately compromised in their defense against the parasite, as they may still activate the lectin pathway through ficolins and CL-11. Here, we assessed MASP-2-deficient mice, the only presently available mouse line with total lectin pathway deficiency, for a phenotype in T. cruzi infection. Total absence of lectin pathway functional activity did not confer higher susceptibility to T. cruzi infection, suggesting that it plays a minor role in the immune response against this parasite. PMID:25548381

Ribeiro, Carolina H; Lynch, Nicholas J; Stover, Cordula M; Ali, Youssif M; Valck, Carolina; Noya-Leal, Francisca; Schwaeble, Wilhelm J; Ferreira, Arturo

2015-02-01

83

Proliferative Glomerulonephritis Secondary to Dysfunction of the Alternative Pathway of Complement  

PubMed Central

Summary Background and objectives dense deposit disease (DDD) is the prototypical membranoproliferative glomerulonephritis (MPGN), in which fluid-phase dysregulation of the alternative pathway (AP) of complement results in the accumulation of complement debris in the glomeruli, often producing an MPGN pattern of injury in the absence of immune complexes. A recently described entity referred to as GN with C3 deposition (GN-C3) bears many similarities to DDD. The purpose of this study was to evaluate AP function in cases of GN-C3. Design, setting, participants, & measurements Five recent cases of MPGN with extensive C3 deposition were studied. Renal biopsy in one case exhibited the classic findings of DDD. Three cases showed GN-C3 in the absence of significant Ig deposition; however, the classic hallmark of DDD—dense deposits along the glomerular basement membranes and mesangium—was absent. The remaining case exhibited features of both DDD and GN-C3. Results Evidence of AP activation was demonstrable in all cases and included increased levels of soluble membrane attack complex (all cases), positive AP functional assays (four cases), and a positive hemolytic assay (one case). Autoantibodies were found to C3 convertase (two cases) and to factor H (one case). Factor H mutation screening identified the H402 allele (all cases) and a c.C2867T p.T956M missence mutation (one case). Laser microdissection and mass spectrometry of glomeruli of GN-C3 (two cases) showed a proteomic profile very similar to DDD. Conclusions These studies implicate AP dysregulation in a spectrum of rare renal diseases that includes GN-C3 and DDD. PMID:21415311

Fervenza, Fernando C.; Zhang, Yuzhou; Nasr, Samih H.; Leung, Nelson; Vrana, Julie; Cramer, Carl; Nester, Carla M.; Smith, Richard J. H.

2011-01-01

84

Complement blockade with a C1 esterase inhibitor in paroxysmal nocturnal hemoglobinuria.  

PubMed

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, clonal, hematopoietic stem cell disorder that manifests with a complement-mediated hemolytic anemia, bone marrow failure, and a propensity for thrombosis. These patients experience both intra- and extravascular hemolysis in the context of underlying complement activation. Currently eculizumab effectively blocks the intravascular hemolysis PNH. There remains an unmet clinical need for a complement inhibitor with activity early in the complement cascade to block complement at the classical and alternative pathways. C1 esterase inhibitor (C1INH) is an endogenous human plasma protein that has broad inhibitory activity in the complement pathway through inhibition of the classical pathway by binding C1r and C1s and inhibits the mannose-binding lectin-associated serine proteases in the lectin pathway. In this study, we show that commercially available plasma derived C1INH prevents lysis induced by the alternative complement pathway of PNH erythrocytes in human serum. Importantly, C1INH was able to block the accumulation of C3 degradation products on CD55 deficient erythrocytes from PNH patient on eculizumab therapy. This could suggest a role for inhibition of earlier phases of the complement cascade than that currently inhibited by eculizumab for incomplete or nonresponders to that therapy. PMID:25034232

DeZern, Amy E; Uknis, Marc; Yuan, Xuan; Mukhina, Galina L; Varela, Juan; Saye, JoAnne; Pu, Jeffrey; Brodsky, Robert A

2014-10-01

85

Complement Blockade with a C1 Esterase Inhibitor in Paroxysmal Nocturnal Hemoglobinuria  

PubMed Central

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, clonal, hematopoietic stem cell disorder that manifests with a complement-mediated hemolytic anemia, bone marrow failure and a propensity for thrombosis. These patients experience both intra- and extravascular hemolysis in the context of underlying complement activation. Currently eculizumab effectively blocks the intravascular hemolysis PNH. There remains an unmet clinical need for a complement inhibitor with activity early in the complement cascade to block complement at the classical and alternative pathways. C1 esterase inhibitor (C1INH) is an endogenous human plasma protein that has broad inhibitory activity in the complement pathway through inhibition of the classical pathway by binding C1r and C1s and inhibits the mannose-binding lectin-associated serine proteases in the lectin pathway. In this study, we show that commercially available plasma derived C1INH prevents lysis induced by the alternative complement pathway, of PNH erythrocytes in human serum. Importantly, C1INH was able to block the accumulation of C3 degradation products on CD55 deficient erythrocytes from PNH patient on eculizumab therapy. This could suggest a role for inhibition of earlier phases of the complement cascade than that currently inhibited by eculizumab for incomplete or non-responders to that therapy. PMID:25034232

DeZern, Amy E.; Uknis, Marc; Yuan, Xuan; Mukhina, Galina L; Varela, Juan; Saye, JoAnne; Pu, Jeffrey; Brodsky, Robert A.

2014-01-01

86

Inhibition of the alternative complement activation pathway in traumatic brain injury by a monoclonal anti-factor B antibody: a randomized placebo-controlled study in mice  

Microsoft Academic Search

BACKGROUND: The posttraumatic response to traumatic brain injury (TBI) is characterized, in part, by activation of the innate immune response, including the complement system. We have recently shown that mice devoid of a functional alternative pathway of complement activation (factor B-\\/- mice) are protected from complement-mediated neuroinflammation and neuropathology after TBI. In the present study, we extrapolated this knowledge from

Iris Leinhase; Michal Rozanski; Denise Harhausen; Joshua M Thurman; Oliver I Schmidt; Amir M Hossini; Mohy E Taha; Daniel Rittirsch; Peter A Ward; V Michael Holers; Wolfgang Ertel; Philip F Stahel

2007-01-01

87

Complement in patients receiving maintenance hemodialysis: functional screening and quantitative analysis  

PubMed Central

Background The complement system is vital for innate immunity and is implicated in the pathogenesis of inflammatory diseases and the mechanism of host defense. Complement deficiencies occasionally cause life-threatening diseases. In hemodialysis (HD) patients, profiles on complement functional activity and deficiency are still obscure. The objectives of the present study were to measure the functional complement activities of the classical pathway (CP), lectin pathway (LP) and alternative pathway (AP) using a novel method and consequently to elucidate the rates of deficiencies among HD patients. Methods In the present study, 244 HD patients at one dialysis center and 204 healthy controls were enrolled. Functional complement activities were measured simultaneously using the Wielisa®-kit. The combination of the results of these three pathway activities allows us to speculate which candidate complement is deficient; subsequently, the deficient complement was determined. Results All three functional complement activities were significantly higher in the HD patients than in the control group (P < 0.01 for all cases). After identifying candidates in both groups with complement deficiencies using the Wielisa®-kit, 16 sera (8.8%) with mannose-binding lectin (MBL) deficiency, 1 serum (0.4%) with C4 deficiency, 1 serum (0.4%) with C9 deficiency, and 1 serum (0.4%) with B deficiency were observed in the HD group, and 18 sera (8.8%) with MBL deficiency and 1 serum (0.5%) with B deficiency were observed in the control group. There were no significant differences in the 5-year mortality rate between each complement-deficient group and the complement-sufficient group among the HD patients. Conclusion This is the first report that profiles complement deficiencies by simultaneous measurement of functional activities of the three complement pathways in HD patients. Hemodialysis patients frequently suffer from infections or malignancies, but functional complement deficiencies do not confer additional risk of mortality. PMID:21134272

2010-01-01

88

Characterization of a Factor H Mutation That Perturbs the Alternative Pathway of Complement in a Family with Membranoproliferative GN  

PubMed Central

Complement C3 activation is a characteristic finding in membranoproliferative GN (MPGN). This activation can be caused by immune complex deposition or an acquired or inherited defect in complement regulation. Deficiency of complement factor H has long been associated with MPGN. More recently, heterozygous genetic variants have been reported in sporadic cases of MPGN, although their functional significance has not been assessed. We describe a family with MPGN and acquired partial lipodystrophy. Although C3 nephritic factor was shown in family members with acquired partial lipodystrophy, it did not segregate with the renal phenotype. Genetic analysis revealed a novel heterozygous mutation in complement factor H (R83S) in addition to known risk polymorphisms carried by individuals with MPGN. Patients with MPGN had normal levels of factor H, and structural analysis of the mutant revealed only subtle alterations. However, functional analysis revealed profoundly reduced C3b binding, cofactor activity, and decay accelerating activity leading to loss of regulation of the alternative pathway. In summary, this family showed a confluence of common and rare functionally significant genetic risk factors causing disease. Data from our analysis of these factors highlight the role of the alternative pathway of complement in MPGN. PMID:24722444

Wong, Edwin K.S.; Anderson, Holly E.; Herbert, Andrew P.; Challis, Rachel C.; Brown, Paul; Reis, Geisilaine S.; Tellez, James O.; Strain, Lisa; Fluck, Nicholas; Humphrey, Ann; Macleod, Alison; Richards, Anna; Ahlert, Daniel; Santibanez-Koref, Mauro; Barlow, Paul N.; Marchbank, Kevin J.; Harris, Claire L.; Goodship, Timothy H.J.

2014-01-01

89

Characterization of a factor H mutation that perturbs the alternative pathway of complement in a family with membranoproliferative GN.  

PubMed

Complement C3 activation is a characteristic finding in membranoproliferative GN (MPGN). This activation can be caused by immune complex deposition or an acquired or inherited defect in complement regulation. Deficiency of complement factor H has long been associated with MPGN. More recently, heterozygous genetic variants have been reported in sporadic cases of MPGN, although their functional significance has not been assessed. We describe a family with MPGN and acquired partial lipodystrophy. Although C3 nephritic factor was shown in family members with acquired partial lipodystrophy, it did not segregate with the renal phenotype. Genetic analysis revealed a novel heterozygous mutation in complement factor H (R83S) in addition to known risk polymorphisms carried by individuals with MPGN. Patients with MPGN had normal levels of factor H, and structural analysis of the mutant revealed only subtle alterations. However, functional analysis revealed profoundly reduced C3b binding, cofactor activity, and decay accelerating activity leading to loss of regulation of the alternative pathway. In summary, this family showed a confluence of common and rare functionally significant genetic risk factors causing disease. Data from our analysis of these factors highlight the role of the alternative pathway of complement in MPGN. PMID:24722444

Wong, Edwin K S; Anderson, Holly E; Herbert, Andrew P; Challis, Rachel C; Brown, Paul; Reis, Geisilaine S; Tellez, James O; Strain, Lisa; Fluck, Nicholas; Humphrey, Ann; Macleod, Alison; Richards, Anna; Ahlert, Daniel; Santibanez-Koref, Mauro; Barlow, Paul N; Marchbank, Kevin J; Harris, Claire L; Goodship, Timothy H J; Kavanagh, David

2014-11-01

90

The relative importance of the classical and alternative complement pathways in serum bactericidal activity against Escherichia coli.  

PubMed

The relative importance of the classical and alternative complement pathways in serum bactericidal activity against Escherichia coli strains of the common urinary O-serogroups has been assessed with strains that differ widely in their sensitivity to normal human serum. With most promptly serum-sensitive strains, rapid killing occurred, mediated by the classical pathway and, when this pathway was eliminated, delayed killing by alternative-pathway activity occurred. However, one strain of serogroup O1 was affected by the classical pathway only and a strain of serogroup O9 was killed rapidly by the alternative pathway. Strains with delayed sensitivity to normal human serum were largely, and in some cases exclusively, affected by the classical pathway. When added to heat-inactivated serum, some strains showed no significant growth whereas the viable numbers of other test strains increased more than 50-fold in 3 h. Whether this variation is due to differences in nutritional requirements or sensitivity to some non-complement-dependent bacteriostatic mechanism remains to be determined. PMID:6401815

Roberts, A P; Phillips, R

1983-02-01

91

The indoleamine 2,3-dioxygenase pathway controls complement-dependent enhancement of chemo-radiation therapy against murine glioblastoma  

PubMed Central

Background Indoleamine 2,3-dioxygenase (IDO) is an enzyme with immune-suppressive properties that is commonly exploited by tumors to evade immune destruction. Anti-tumor T cell responses can be initiated in solid tumors, but are immediately suppressed by compensatory upregulation of immunological checkpoints, including IDO. In addition to these known effects on the adaptive immune system, we previously showed widespread, T cell-dependent complement deposition during allogeneic fetal rejection upon maternal treatment with IDO-blockade. We hypothesized that IDO protects glioblastoma from the full effects of chemo-radiation therapy by preventing vascular activation and complement-dependent tumor destruction. Methods To test this hypothesis, we utilized a syngeneic orthotopic glioblastoma model in which GL261 glioblastoma tumor cells were stereotactically implanted into the right frontal lobes of syngeneic mice. These mice were treated with IDO-blocking drugs in combination with chemotherapy and radiation therapy. Results Pharmacologic inhibition of IDO synergized with chemo-radiation therapy to prolong survival in mice bearing intracranial glioblastoma tumors. We now show that pharmacologic or genetic inhibition of IDO allowed chemo-radiation to trigger widespread complement deposition at sites of tumor growth. Chemotherapy treatment alone resulted in collections of perivascular leukocytes within tumors, but no complement deposition. Adding IDO-blockade led to upregulation of VCAM-1 on vascular endothelium within the tumor microenvironment, and further adding radiation in the presence of IDO-blockade led to widespread deposition of complement. Mice genetically deficient in complement component C3 lost all of the synergistic effects of IDO-blockade on chemo-radiation-induced survival. Conclusions Together these findings identify a novel mechanistic link between IDO and complement, and implicate complement as a major downstream effector mechanism for the beneficial effect of IDO-blockade after chemo-radiation therapy. We speculate that this represents a fundamental pathway by which the tumor regulates intratumoral vascular activation and protects itself from immune-mediated tumor destruction. PMID:25054064

2014-01-01

92

Complement-related serine proteases in tunicates and vertebrates  

Microsoft Academic Search

Serum mannose-binding lectin binds to pathogens in association with a serine protease termed MASP, and in this form, plays a crucial role in innate immunity by activating complement in a manner similar to activation via the classical pathway. MASP, C1r and C1s belong to the same family of serine proteases. In addition to its presence in advanced species, MASP also

Misao Matsushita; Yuichi Endo; Masaru Nonaka; Teizo Fujita

1998-01-01

93

Strain influences on inflammatory pathway activation, cell infiltration and complement cascade after traumatic brain injury in the rat.  

PubMed

Increasing evidence suggests that genetic background affects outcome of traumatic brain injuries (TBI). Still, there is limited detailed knowledge on what pathways/processes are affected by genetic heterogeneity. The inbred rat strains DA and PVG differ in neuronal survival following TBI. We here carried out global expressional profiling to identify differentially regulated pathways governing the response to an experimental controlled brain contusion injury. One of the most differentially regulated molecular networks concerned immune cell trafficking. Subsequent characterization of the involved cells using flow cytometry demonstrated greater infiltration of neutrophils and monocytes, as well as a higher degree of microglia activation in DA compared to PVG rats. In addition, DA rats displayed a higher number of NK cells and a higher ratio of CD161bright compared to CD161dim NK cells. Local expression of complement pathway molecules such as C1 and C3 was higher in DA and both the key complement component C3 and membrane-attack complex (MAC) could be demonstrated on axons and nerve cells. A stronger activation of the complement system in DA was associated with higher cerebrospinal fluid levels of neurofilament-light, a biomarker for nerve/axonal injury. In summary, we demonstrate substantial differences between DA and PVG rats in activation of inflammatory pathways; in particular, immune cell influx and complement activation associated with neuronal/axonal injury after TBI. These findings suggest genetic influences acting on inflammatory activation to be of importance in TBI and motivate further efforts using experimental forward genetics to identify genes/pathways that affect outcome. PMID:23044177

Al Nimer, Faiez; Lindblom, Rickard; Ström, Mikael; Guerreiro-Cacais, André Ortlieb; Parsa, Roham; Aeinehband, Shahin; Mathiesen, Tiit; Lidman, Olle; Piehl, Fredrik

2013-01-01

94

Down-Regulation of Complement Receptors on the Surface of Host Monocyte Even as In Vitro Complement Pathway Blocking Interferes in Dengue Infection  

PubMed Central

In dengue virus (DENV) infection, complement system (CS) activation appears to have protective and pathogenic effects. In severe dengue fever (DF), the levels of DENV non-structural-1 protein and of the products of complement activation, including C3a, C5a and SC5b-9, are higher before vascular leakage occurs, supporting the hypothesis that complement activation contributes to unfavourable outcomes. The clinical manifestations of DF range from asymptomatic to severe and even fatal. Here, we aimed to characterise CS by their receptors or activation product, in vivo in DF patients and in vitro by DENV-2 stimulation on monocytes. In comparison with healthy controls, DF patients showed lower expression of CR3 (CD11b), CR4 (CD11c) and, CD59 on monocytes. The DF patients who were high producers of SC5b-9 were also those that showed more pronounced bleeding or vascular leakage. Those findings encouraged us to investigate the role of CS in vitro, using monocytes isolated from healthy subjects. Prior blocking with CR3 alone (CD11b) or CR3 (CD11b/CD18) reduced viral infection, as quantified by the levels of intracellular viral antigen expression and soluble DENV non-structural viral protein. However, we found that CR3 alone (CD11b) or CR3 (CD11b/CD18) blocking did not influence major histocompatibility complex presentation neither active caspase-1 on monocytes, thus probably ruling out inflammasome-related mechanisms. Although it did impair the secretion of tumour necrosis factor alpha and interferon alpha. Our data provide strategies of blocking CR3 (CD11b) pathways could have implications for the treatment of viral infection by antiviral-related mechanisms. PMID:25061945

Marinho, Cintia Ferreira; Azeredo, Elzinandes Leal; Torrentes-Carvalho, Amanda; Marins-Dos-Santos, Alessandro; Kubelka, Claire Fernandes; de Souza, Luiz José; Cunha, Rivaldo Venâncio; de-Oliveira-Pinto, Luzia Maria

2014-01-01

95

Mannose-Binding Lectin 2 Gene and Risk of Adult Glioma  

PubMed Central

Background and Aims The immune system is likely to play a key role in the etiology of gliomas. Genetic polymorphisms in the mannose-binding lectin gene, a key activator in the lectin complement pathway, have been associated with risk of several cancers. Methods To examine the role of the lectin complement pathway, we combined data from prospectively collected cohorts with available DNA specimens. Using a nested case-control design, we genotyped 85 single nucleotide polymorphisms (SNPs) in 9 genes in the lectin complement pathway and 3 additional SNPs in MBL2 were tested post hoc). Initial SNPs were selected using tagging SNPs for haplotypes; the second group of SNPs for MBL2 was selected based on functional SNPs related to phenotype. Associations were examined using logistic regression analysis. All statistical tests were two-sided. Nominal p-values are presented and are not corrected for multiple comparisons. Results A total of 143 glioma cases and 419 controls were available for this analysis. Statistically significant associations were observed for two SNPs in the mannose-binding lectin 2 (ML2) gene and risk of glioma (rs1982266 and rs1800450, test for trend p?=?0.003 and p?=?0.04, respectively, using the additive model). One of these SNPs, rs1800450, was associated with a 58% increase in glioma risk among those carrying one or two mutated alleles (odds ratio?=?1.58, 95% confidence interval?=?0.99–2.54), compared to those homozygous for the wild type allele. Conclusions Overall, our findings suggest that MBL may play a role in the etiology of glioma. Future studies are needed to confirm these findings which may be due to chance, and if reproduced, to determine mechanisms that link glioma pathogenesis with the MBL complement pathway. PMID:23637788

Michaud, Dominique S.; Siddiq, Afshan; Cox, David G.; Backes, Danielle M.; Calboli, Federico C. F.; Sughrue, Michael E.; Gaziano, J. Michael; Ma, Jing; Stampfer, Meir; Tworoger, Shelley S.; Hunter, David J.; Camargo, Carlos A.; Parsa, Andrew T.

2013-01-01

96

The complement cascade and renal disease.  

PubMed

Serum complement cascade, a part of innate immunity required for host protection against invading pathogens, is also a mediator of various forms of disease and injury. It is activated by classical, lectin, and alternative pathways that lead to activation of C3 component by C3 convertases, release of C3b opsonin, C5 conversion and eventually membrane attack complex formation. The tightly regulated activation process yields also C3a and C5a anaphylatoxins, which target a broad spectrum of immune and non-immune cells. The review discusses the involvement of the complement cascade in kidney disease pathogenesis and injury. The role of the complement pathways in autoantibody-mediated forms of glomerulonephritis (lupus nephritis, anti-glomerular basement membrane disease, anti-neutrophil cytoplasmic autoantibody-induced or membranoproliferative glomerulonephritis, membranous nephropathy), C3 glomerulopathy, atypical forms of hemolytic uremic syndrome, ischemic-reperfusion injury of transplanted kidney, and antibody-mediated renal allograft rejection are discussed. The disturbances in complement activation and regulation with underlying genetics are presented and related to observed pathology. Also promising strategies targeting the complement system in complement-related disorders are mentioned. PMID:24030732

Ko?cielska-Kasprzak, Katarzyna; Bartoszek, Dorota; Myszka, Marta; Zabi?ska, Marcelina; Klinger, Marian

2014-02-01

97

Genetic Variation in Complement Component 2 of the Classical Complement Pathway is Associated with Increased Mortality and Infection: A Study of 627 Trauma Patients  

PubMed Central

Trauma is a disease of inflammation. Complement Component 2 (C2) is a protease involved in activation of complement through the classical pathway and has been implicated in a variety of chronic inflammatory diseases. We hypothesized that genetic variation in C2 (E318D) identifies a high-risk subgroup of trauma patients reflecting increased mortality and infection (Ventilator associated pneumonia: VAP). Consequently, genetic variation in C2 may stratify patient risk and illuminate underlying mechanisms for therapeutic intervention. Methods DNA samples from 702 trauma patients were genotyped for C2 E318D and linked with covariates (age: mean 42.8 years, gender: 74% male, ethnicity: 80% Caucasian, mechanism: 84% blunt, ISS: mean 25.0, admission lactate: mean 3.13 mEq/L) and outcomes: mortality 9.9% and VAP: 18.5%. VAP was defined by quantitative bronchoalveolar lavage (>104). Multivariate regression determined the relationship of genotype and covariates to risk of death and VAP. However, patients with ISS ? 45 were excluded from the multivariate analysis, as magnitude of injury overwhelms genetics and covariates in determining outcome. Results 52 patients (8.3%) had the high-risk heterozygous genotype, associated with a significant increase in mortality and VAP. Conclusion In 702 trauma patients, 8.3% had a high-risk genetic variation in C2 associated with increased mortality (OR=2.65) and infection (OR=2.00). This variation: 1) Identifies a previously unknown high risk group for infection and mortality; 2) Can be determined on admission; 3) May provide opportunity for early therapeutic intervention; and 4) Requires validation in a distinct cohort of patients. PMID:19430225

Morris, John A.; Francois, Cedric; Olson, Paul K.; Cotton, Bryan A.; Summar, Marshall; Jenkins, Judith M.; Norris, Patrick R.; Moore, Jason H.; Williams, Anna E.; McNew, Brent S.; Canter, Jeffrey A.

2009-01-01

98

A lectin from Musca domestica pupae stimulates B cell proliferation and enhances IL-12 production via ERK1/2-NF-?B signaling pathways.  

PubMed

A D-galactose-specific lectin, MW = 40 kDa, had been purified from pupae of Musca domestica (MPL). MPL significantly promoted the proliferation of B cells and enhanced the production of IL-12 in a dose-dependent manner. MPL stimulated I?B-? degradation, NF-?B translocation and ERK1/2 phosphorylation which played an upstream role for NF-?B in MPL-induced B cells. Moreover, MPL regulated cell proliferation and induced IL-12 production through ERK1/2-NF-?B signaling pathway. PMID:21448746

Cao, Xiaohong; Li, Yuanyuan; Hou, Lihua; Zhou, Minghui; Wang, Zhuo; Cui, Qi; Gao, Xiaohe; Wang, Chunling

2011-08-01

99

Dissecting the complement pathway in hepatic injury and regeneration with a novel protective strategy  

PubMed Central

Liver resection is commonly performed under ischemic conditions, resulting in two types of insult to the remnant liver: ischemia reperfusion injury (IRI) and loss of liver mass. Complement inhibition is recognized as a potential therapeutic modality for IRI, but early complement activation products are also essential for liver regeneration. We describe a novel site-targeted murine complement inhibitor, CR2-CD59, which specifically inhibits the terminal membrane attack complex (MAC), and we use this protein to investigate the complement-dependent balance between liver injury and regeneration in a clinical setting of pharmacological inhibition. CR2-CD59 did not impact in vivo generation of C3 and C5 activation products but was as effective as the C3 activation inhibitor CR2-Crry at ameliorating hepatic IRI, indicating that the MAC is the principle mediator of hepatic IRI. Furthermore, unlike C3 or C5 inhibition, CR2-CD59 was not only protective but significantly enhanced hepatocyte proliferation after partial hepatectomy, including when combined with ischemia and reperfusion. Remarkably, CR2-CD59 also enhanced regeneration after 90% hepatectomy and improved long-term survival from 0 to 70%. CR2-CD59 functioned by increasing hepatic TNF and IL-6 levels with associated STAT3 and Akt activation, and by preventing mitochondrial depolarization and allowing recovery of ATP stores. PMID:25113972

Marshall, Keely M.; Zhong, Zhi; Atkinson, Carl

2014-01-01

100

Impact of Mannose-Binding Lectin Deficiency on Radiocontrast-Induced Renal Dysfunction  

PubMed Central

Contrast-induced nephropathy (CIN) is the third leading cause of acute renal failure in hospitalized patients. Endothelial dysfunction, renal medullary ischemia, and tubular toxicity are regarded as the most important factors in the pathogenesis of CIN. Mannose-binding lectin (MBL), a pattern recognition protein of the lectin pathway of complement, has been found to aggravate and mediate tissue damage during experimental renal ischemia/reperfusion (I/R) injury which was alleviated by inhibition with C1 inhibitor, a potent MBL, and lectin pathway inhibitor. In this paper, we highlight the potential role of MBL in the pathogenesis of human CIN. In experimental I/R models, MBL was previously found to induce tubular cell death independent of the complement system. In addition, after binding to vascular endothelial cells, MBL and its associated serine proteases were able to trigger a proinflammatory reaction and contribute to endothelial dysfunction. In humans, urinary MBL was increased after administration of contrast media and in individuals with CIN. Moreover, individuals with normal/high MBL levels were at increased risk to develop radiocontrast-induced renal dysfunction. Hence, MBL and the lectin pathway seem to be a promising target given that a licensed, powerful, human recombinant inhibitor exits to be added to the scarce armamentarium currently available for prophylaxis of CIN. PMID:24386641

Osthoff, Michael; Trendelenburg, Marten

2013-01-01

101

Human pentraxin 3 binds to the complement regulator c4b-binding protein.  

PubMed

The long pentraxin 3 (PTX3) is a soluble recognition molecule with multiple functions including innate immune defense against certain microbes and the clearance of apoptotic cells. PTX3 interacts with recognition molecules of the classical and lectin complement pathways and thus initiates complement activation. In addition, binding of PTX3 to the alternative complement pathway regulator factor H was shown. Here, we show that PTX3 binds to the classical and lectin pathway regulator C4b-binding protein (C4BP). A PTX3-binding site was identified within short consensus repeats 1-3 of the C4BP ?-chain. PTX3 did not interfere with the cofactor activity of C4BP in the fluid phase and C4BP maintained its complement regulatory activity when bound to PTX3 on surfaces. While C4BP and factor H did not compete for PTX3 binding, the interaction of C4BP with PTX3 was inhibited by C1q and by L-ficolin. PTX3 bound to human fibroblast- and endothelial cell-derived extracellular matrices and recruited functionally active C4BP to these surfaces. Whereas PTX3 enhanced the activation of the classical/lectin pathway and caused enhanced C3 deposition on extracellular matrix, deposition of terminal pathway components and the generation of the inflammatory mediator C5a were not increased. Furthermore, PTX3 enhanced the binding of C4BP to late apoptotic cells, which resulted in an increased rate of inactivation of cell surface bound C4b and a reduction in the deposition of C5b-9. Thus, in addition to complement activators, PTX3 interacts with complement inhibitors including C4BP. This balanced interaction on extracellular matrix and on apoptotic cells may prevent excessive local complement activation that would otherwise lead to inflammation and host tissue damage. PMID:21915248

Braunschweig, Anne; Józsi, Mihály

2011-01-01

102

Human Pentraxin 3 Binds to the Complement Regulator C4b-Binding Protein  

PubMed Central

The long pentraxin 3 (PTX3) is a soluble recognition molecule with multiple functions including innate immune defense against certain microbes and the clearance of apoptotic cells. PTX3 interacts with recognition molecules of the classical and lectin complement pathways and thus initiates complement activation. In addition, binding of PTX3 to the alternative complement pathway regulator factor H was shown. Here, we show that PTX3 binds to the classical and lectin pathway regulator C4b-binding protein (C4BP). A PTX3-binding site was identified within short consensus repeats 1–3 of the C4BP ?-chain. PTX3 did not interfere with the cofactor activity of C4BP in the fluid phase and C4BP maintained its complement regulatory activity when bound to PTX3 on surfaces. While C4BP and factor H did not compete for PTX3 binding, the interaction of C4BP with PTX3 was inhibited by C1q and by L-ficolin. PTX3 bound to human fibroblast- and endothelial cell-derived extracellular matrices and recruited functionally active C4BP to these surfaces. Whereas PTX3 enhanced the activation of the classical/lectin pathway and caused enhanced C3 deposition on extracellular matrix, deposition of terminal pathway components and the generation of the inflammatory mediator C5a were not increased. Furthermore, PTX3 enhanced the binding of C4BP to late apoptotic cells, which resulted in an increased rate of inactivation of cell surface bound C4b and a reduction in the deposition of C5b-9. Thus, in addition to complement activators, PTX3 interacts with complement inhibitors including C4BP. This balanced interaction on extracellular matrix and on apoptotic cells may prevent excessive local complement activation that would otherwise lead to inflammation and host tissue damage. PMID:21915248

Braunschweig, Anne; Józsi, Mihály

2011-01-01

103

Neuronal expression of mRNAs for complement proteins of the classical pathway in Alzheimer brain  

Microsoft Academic Search

To determine possible sources of complement proteins in brain, we investigated by in situ hybridization expression of the mRNAs of C1q, C2, C3, C4, C5, C6, C7, C8 and C9 in postmortem Alzheimer disease (AD) and control brain tissue. We found detectable hybridization for all these components in the temporal cortex and hippocampus, with significantly higher levels being found in

Yong Shen; Rena Li; Edith G McGeer; Patrick L McGeer

1997-01-01

104

Local release of properdin in the cellular microenvironment: role in pattern recognition and amplification of the alternative pathway of complement  

PubMed Central

Properdin, the only positive regulatory protein of the complement system, acts as both a stabilizer of the alternative pathway (AP) convertases and as a selective pattern recognition molecule of certain microorganisms and host cells (i.e., apoptotic/necrotic cells) by serving as a platform for de novo C3b,Bb assembly. Properdin, a highly positively charged protein, normally exists as cyclic dimers (P2), trimers (P3), and tetramers (P4) of head-to-tail associations of monomeric 53 kDa subunits. While most complement proteins are produced mainly in the liver, properdin is synthesized primarily by various cell types, including neutrophils, monocytes, primary T cells, and shear-stressed endothelial cells resulting in properdin serum levels of 4–25 ?g/ml. Multiple inflammatory agonists stimulate the release of properdin from stimulated leukocytes into the cellular microenvironment. Concentrated, focused increases in properdin levels may lead to stabilization and initiation of AP convertases, thus greatly amplifying the complement response to a local stimulus. This review highlights current knowledge related to these properties and discusses the implications of properdin production in a pro-inflammatory microenvironment. PMID:23335922

Cortes, Claudio; Ohtola, Jennifer A.; Saggu, Gurpanna; Ferreira, Viviana P.

2013-01-01

105

Possible mechanisms of the first step of the classical complement activation pathway: binding and activation of C1.  

PubMed Central

Different immunoglobulin preparations of human monoclonal IgM, normal human and rat IgG, as well as purified rabbit antibodies were treated by various methods, fragmentation, aggregation and complexing with antigen. The ability of the treated and untreated preparations to fix isolated human C1, to activate the classical complement pathway (to consume C4 in normal human serum) were compared. It was found that the different methods affected the conformation of the immunoglobulin molecules in different ways and induced changes to a greater or lesser extent in the two capacities of the preparations tested. In the case of the monoclonal IgM preparation a strong C1-fixation was observed without measurable complement activation. Other preparations, interfacially aggregated human IgG, BSA-anti-BSA and OA-anti-OA immune complexes had a very weak C1-fixing but a marked complement activating capacity. Some preparations, e.g. heat-aggregated IgG, both fixed and activated C1 effectively, aggregates with a complement-activating capacity without C1-fixing effect were separated by gel-filtration. It was demonstrated further, that at a given time only a part of the activated C1 molecules could be found fixed to the immunoglobulins, the other part was released into the fluid phase after activation. On the basis of the results of this and previous studies a hypothesis is proposed suggesting three possible results of the interaction between C1 and the different preparations: (1) firm fixation and activation; (2) binding not followed by activation and (3) a transient binding leading to activation. The possible application of this hypothesis for the interpretation of the results of the different methods for detecting immune complexes is discussed. PMID:104923

Füst, G; Medgyesi, G A; Rajnavölgyi, E; Csécsi-Nagy, M; Czikora, K; Gergely, J

1978-01-01

106

CNL, a ricin B-like lectin from mushroom Clitocybe nebularis, induces maturation and activation of dendritic cells via the toll-like receptor 4 pathway.  

PubMed

A novel lectin, isolated from the basidiomycete mushroom Clitocybe nebularis and termed C. nebularis lectin (CNL), exhibits an immunostimulatory effect on the most potent antigen-presenting cells, the dendritic cells (DCs). Treatment of human monocyte-derived DCs with CNL in doses from 1 to 10??g/ml resulted in a dose-dependent induction of overall DC maturation characteristics. Exposure of DCs to CNL for 48?hr resulted in extensive up-regulation of co-stimulatory molecules CD80 and CD86, as well as of the maturation marker CD83 and HLA-DR molecules. Such CNL-matured DCs (CNL-DCs) were capable of inducing a T helper type 1-polarized response in naive CD4+ ?CD45RA+ T cells in 5-day allogeneic co-cultures. The allostimulatory potential of CNL-DCs was significantly increased relative to untreated controls, as was their capacity to produce several pro-inflammatory cytokines such as interleukin-6, interleukin-8 and tumour necrosis factor-?. By using a specific Toll-like receptor 4 (TLR4) signalling inhibitor, CLI-095, as well as Myd88 inhibitory peptide, we have shown that DC activation by CNL is completely dependent on the TLR4 activation pathway. Furthermore, activation of TLR4 by CNL was confirmed via TLR4 reporter assay. Measurement of p65 nuclear factor-?B and p38 mitogen-activated protein kinase (MAPK) phosphorylation levels following CNL stimulation of DCs revealed primarily an increase in nuclear factor-?B activity, with less effect on the induction of p38 MAPK signalling than of lipopolysaccharide-matured DCs. The CNL had the ability to activate human DCs in such a way as to subsequently direct T helper type 1 T-cell responses. Our results encourage the use of mushroom-derived lectins for use in therapeutic strategies with aims such as to strengthen anti-tumour immune responses. PMID:22044067

Svajger, Urban; Pohleven, Jure; Kos, Janko; Strukelj, Borut; Jeras, Matjaž

2011-12-01

107

Nucleocytoplasmic lectins  

Microsoft Academic Search

This review summarizes studies on lectins that have been documented to be in the cytoplasm and nucleus of cells. Of these intracellular lectins, the most extensively studied are members of the galectin family. Galectin-1 and galectin-3 have been identified as pre-mRNA splicing factors in the nucleus, in conjunction with their interacting ligand, Gemin4. Galectin-3, -7, and -12 regulate growth, cell

John L Wang; Richard M Gray; Kevin C Haudek; Ronald J Patterson

2004-01-01

108

Inhibitor(s) of the classical complement pathway in mouse serum limit the utility of mice as experimental models of neuromyelitis optica.  

PubMed

Neuromyelitis optica (NMO) is an inflammatory demyelinating disease of the central nervous system in which anti-aquaporin-4 (AQP4) autoantibodies (AQP4-IgG) cause damage to astrocytes by complement-dependent cytotoxicity (CDC). Various approaches have been attempted to produce NMO lesions in rodents, some involving genetically modified mice with altered immune cell function. Here, we found that mouse serum strongly inhibits complement from multiple species, preventing AQP4-IgG-dependent CDC. Effects of mouse serum on complement activation were tested in CDC assays in which AQP4-expressing cells were incubated with AQP4-IgG and complement from different species. Biochemical assays and mass spectrometry were used to characterize complement inhibitor(s) in mouse serum. Sera from different strains of mice produced almost no AQP4-IgG-dependent CDC compared with human, rat and guinea pig sera. Remarkably, addition of mouse serum prevented AQP4-IgG-dependent CDC caused by human, rat or guinea pig serum, with 50% inhibition at <5% mouse serum. Hemolysis assays indicated that the inhibitor(s) in mouse serum target the classical and not the alternative complement pathway. We found that the complement inhibitor(s) in mouse serum were contained in a serum fraction purified with protein-A resin; however, the inhibitor was not IgG as determined using serum from IgG-deficient mice. Mass spectrometry on the protein A-purified fraction produced several inhibitor candidates. The low intrinsic complement activity of mouse serum and the presence of complement inhibitor(s) limit the utility of mouse models to study disorders, such as NMO, involving the classical complement pathway. PMID:24980869

Ratelade, Julien; Verkman, A S

2014-11-01

109

Acylation-stimulating protein deficiency and altered adipose tissue in alternative complement pathway knockout mice.  

PubMed

Acylation-stimulating protein (C3adesArg/ASP) is an adipokine that acts on its receptor C5L2 to stimulate triglyceride (TG) synthesis in adipose tissue. The present study investigated ASP levels in mouse models of obesity and leanness and the effect of ASP deficiency in C3 knockout (C3KO) mice on adipose tissue morphology. Plasma ASP levels in wild-type (WT) mice correlated positively with plasma nonesterified fatty acids (NEFA) (R = 0.664, P < 0.001) and total cholesterol (R = 0.515, P < 0.001). Plasma ASP was increased by 85% in obese ob/ob leptin-deficient mice and decreased in lean diacylglycerol acyltransferase 1 (DGAT1) KO mice (-54%) and C/EBPalpha(beta/beta) transgenic mice (-70%) compared with WT. Mice lacking alternative complement factor B or adipsin (FBKO or ADKO), required for ASP production, were also ASP deficient. Both FBKO and C3KO mice had delayed postprandial TG and NEFA clearance on low-fat (LF) and high-fat (HF) diets, suggesting that lack of ASP, not C3, drives the metabolic phenotype. Adipocyte size distribution in C3KO mice was polarized (increased number of both small and large cells), with decreased adipsin expression (-33% gonadal HF), DGAT1 expression (-31% to -50%) and DGAT activity (-41%). Overall, a reduction/deficiency in ASP is associated with an antiadipogenic state and ASP may provide a target for controlling fat storage. PMID:18160458

Paglialunga, Sabina; Fisette, Alexandre; Yan, Yafeng; Deshaies, Yves; Brouillette, Jean-Francois; Pekna, Marcela; Cianflone, Katherine

2008-03-01

110

A comparative study of mammalian and reptilian alternative pathway of complement-mediated killing of the Lyme disease spirochete (Borrelia burgdorferi).  

PubMed

The potential bactericidal activity of the alternative complement pathway of mammalian and reptilian sera to Borrelia burgdorferi sensu stricto (s.s.) was evaluated in vitro. Complement-mediated killing was observed when cultured spirochetes were inoculated into sera from the western fence lizard (Sceloporus occidentalis) and from the southern alligator lizard (Elgaria multicarinata), but not when they were inoculated into serum from either the deer mouse (Peromyscus maniculatus) or from humans. Spirochetes were still alive after 4 hr in lizard serum that had been preheated at 56 C for 30 min to inactivate complement. Furthermore, when lizard serum was chelated with 10 mM ethylenediaminetetraacetic acid to block all complement activation, borreliacidal activity was arrested. When lizard serum was chelated with 10 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid plus 4 mM MgCl2 to block only classical complement pathway activation, >85% of spirochetes were immobilized within 1 hr. Differences in B. burgdorferi s.s. mortality were not observed when chelators with or without MgCl2 were added to serum from either deer mice or humans. Proteins comprising the alternative complement pathway are responsible for the borreliacidal activity observed in the blood of S. occidentalis and E. multicarinata. PMID:11191895

Kuo, M M; Lane, R S; Giclas, P C

2000-12-01

111

Visual Pathway Study Using in vivo DTI Tractography to Complement Classical Anatomy  

PubMed Central

Background Knowledge of the individual course of the optic radiations (OR) is important to avoid post-operative visual deficits. Cadaveric studies of the visual pathways are limited because it has not been possible to accurately separate the OR from neighboring tracts and results may not apply to individual patients. Diffusion tensor imaging (DTI) studies may be able to demonstrate the relationships between the OR and neighboring fibers in vivo in individual subjects. Objective To use DTI tractography to study the OR and Meyer’s loop (ML) anatomy in vivo. Methods Ten healthy subjects underwent magnetic resonance imaging with diffusion imaging at 3T. Using a fiducial-based DTI tractography tool (Slicer 3.3), seeds were placed near the lateral geniculate nucleus (LGN) to reconstruct individual visual pathways and neighboring tracts. Projections of the optic radiations onto 3D brain models were shown individually in order to quantify relationships to key landmarks. Results Two patterns of visual pathways were found. The OR ran more commonly deep in the whole superior and middle temporal gyri and superior temporal sulcus. The OR was closely surrounded in all cases by an inferior longitudinal fascicle and a parieto/occipito/temporo-pontine fascicle. The mean left and right distances between the tip of the OR and temporal pole were 39.8± 3.8mm and 40.6±5.7 mm, respectively. Conclusion DTI tractography provides a practical complementary method to study the OR and ML anatomy in vivo, and with reference to individual 3D brain anatomy. PMID:21808220

Wu, Wentao; Rigolo, Laura; O’Donnell, Lauren J.; Norton, Isaiah; Shriver, Sargent; Golby, Alexandra J.

2011-01-01

112

Musca domestica pupae lectin induces apoptosis in HepG2 cells through a NF-?B/p65-mediated caspase pathway.  

PubMed

A new lectin (42 kDa) from Musca domestica pupae (MPL) has been known to inhibit proliferation in tumor cells. In this study, flow cytometry analysis showed that MPL induced HepG2 cells apoptosis significantly and the cells were arrested at S phase. MPL inhibited I?B-? degradation and NF-?B/p65 translocation from cytoplasm into nucleus. Simultaneously, the expressions of FLIP, which is a target gene of NF-?B/p65 were down-regulated and the caspase-8 and caspase-3 were then activated to induce apoptosis. Taken together, these results showed that MPL induced a caspase-dependent apoptosis via NF-?B/p65 pathway in HepG2 cells. PMID:22455932

Nie, Jianzeng; Cao, Xiaohong; Zhou, Minghui; Zhang, Xinyuan; Zhang, Rongping; Niu, Lili; Xia, Yan; Hou, Lihua; Wang, Chunling

2012-04-01

113

Role of the complement anaphylatoxin C5a-receptor pathway in atopic dermatitis in mice.  

PubMed

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a genetic background. The C5a?receptor (C5aR) pathway has been reported to be involved in AD; however, the precise pathogenesis remains to be elucidated. In the present study, the contribution of the C5aR pathway to AD in mice was investigated. A BALB/c mouse model of AD was induced by application of 2,4?dinitrochlorobenzene (DNCB) onto hairless dorsal skin. Following DNCB application for 2 weeks, C5aR expression in skin tissue was assessed by reverse transcription quantitative polymerase chain reaction. C5aR expression in skin tissue was significantly increased in mice with AD. In an additional experiment, C5aR antagonist (C5aRA) intracutaneously injected in combination with DNCB treatment. The skin?fold thickness, number of total infiltrating leukocytes and mast cells infiltrating in skin tissue were measured. Interleukin?4 (IL?4) and interferon?? (IFN??) levels in skin tissue and IL?4, IFN??, histamine and immunoglobulin E (IgE) levels in serum were measured using ELISA. The skin?fold thickness, numbers of total infiltrating leukocytes and mast cells in skin tissue, as well as levels of IL?4, IFN??, histamine and IgE were significantly increased in mice with AD. However, simultaneous treatment with C5aRA significantly attenuated increases in skin fold thickness and the numbers of total infiltrating leukocytes and mast cells in skin tissue. Treatment with C5aRA also decreased IL?4 and IFN?? levels in skin tissue, as well as the levels of IL?4, IFN??, histamine and IgE in the serum. In conclusion, C5aRA inhibited AD in mice, possibly through suppression of the C5aR?mediated cascade action of mast cells. PMID:25650554

Dang, Lin; He, Lei; Wang, Yan; Xiong, Jikui; Bai, Bingxue; Li, Yuzhen

2015-06-01

114

Lectin from Canavalia brasiliensis (ConBr) protects hippocampal slices against glutamate neurotoxicity in a manner dependent of PI3K/Akt pathway.  

PubMed

The excitotoxicity induced by excessive activation of the glutamatergic neurotransmission pathway is involved in several neuropathologies. In this sense, molecules that prevent the release of glutamate or the excessive activation of its receptors can be useful in preventing the neuronal cell death observed in these diseases. Lectins are proteins capable of reversible binding to the carbohydrates in glycoconjugates, and some have been used in the study and purification of glutamate receptors. ConBr is a mannose/glucose-binding lectin purified from Canavalia brasiliensis seeds. In the present study, we aimed to evaluate the neuroprotective activity of ConBr against glutamate-induced excitotoxicity. Hippocampal slices were isolated from adult male mice and incubated for 6h in Krebs saline/DMEM buffer alone (control), in the presence of glutamate or glutamate plus ConBr. The phosphorylation of Akt and mitogen activated protein kinases (MAPKs) such as ERK1/2, p38(MAPK) and JNK1/2/3 was evaluated with western blotting. The results indicate that glutamate provoked a reduction in the hippocampal slice viability (-25%), diminished the phosphorylation of Akt and augmented p38(MAPK) and ERK1 phosphorylation. No changes were observed in the phosphorylation of JNK1/2/3 or ERK2. Notably, ConBr, through a mechanism dependent on carbohydrate interaction, prevented the reduction of cell viability and Akt phosphorylation induced by glutamate. Furthermore, in the presence of the PI3K inhibitor LY294002, ConBr was unable to reverse glutamate neurotoxicity. Taken together, our data suggest that the neuroprotective effect of ConBr against glutamate neurotoxicity requires oligosaccharide interaction and is dependent on the PI3K/Akt pathway. PMID:23454192

Jacques, Amanda V; Rieger, Débora K; Maestri, Mariana; Lopes, Mark W; Peres, Tanara V; Gonçalves, Filipe M; Pedro, Daniela Z; Tasca, Carla I; López, Manuela G; Egea, Javier; Nascimento, Kyria S; Cavada, Benildo S; Leal, Rodrigo B

2013-05-01

115

Genome-wide pathway-based association study implicates complement system in the development of Kashin-Beck disease in Han Chinese.  

PubMed

Kashin-Beck disease (KBD) is a chronic osteochondropathy. The pathogenesis of KBD remains unknown. To identify relevant biological pathways for KBD, we conducted a genome-wide pathway-based association study (GWPAS) following by replication analysis, totally using 2743 Chinese Han adults. A modified gene set enrichment algorithm was used to detect association between KBD and 963 biological pathways. Cartilage gene expression analysis and serum complement measurement were performed to evaluate the functional relevance of identified pathway with KBD. We found that the Complement and Coagulation Cascades (CACC) pathway was significantly associated with KBD (P value=3.09×10(-5), false-discovery rate=0.042). Within the CACC pathway, the most significant association was observed at rs1656966 (P value=1.97×10(-4)) of KNG1 gene. Further replication study observed that rs1656966 (P value=0.037) was significantly associated with KBD in an independent validation sample of 1026 subjects. Gene expression analysis observed that CFD (ratio=3.39±2.68), A2M (ratio=3.67±5.63), C5 (ratio=2.65±2.52) and CD46 (ratio=2.29±137) genes of the CACC pathway were up-regulated in KBD articular cartilage compared to healthy articular cartilage. The serum level of complement C5 in KBD patients were significantly higher than that in healthy controls (P value=0.038). Our study is the first to suggest that complement system-related CACC pathway contributed to the development of KBD. PMID:25305519

Zhang, Feng; Wen, Yan; Guo, Xiong; Zhang, Yingang; Wang, Sen; Yang, Tielin; Shen, Hui; Chen, Xiangding; Tan, Lijun; Tian, Qing; Deng, Hong-Wen

2015-02-01

116

Impaired Opsonization with C3b and Phagocytosis of Streptococcus pneumoniae in Sera from Subjects with Defects in the Classical Complement Pathway?  

PubMed Central

Results from studies using mice deficient in specific complement factors and clinical data on patients with an inherited deficiency of the classical complement pathway component C2 suggest that the classical pathway is vital for immunity to Streptococcus pneumoniae. However, the consequences of defects in classical pathway activity for opsonization with C3b and the phagocytosis of different S. pneumoniae serotypes in human serum are not known, and there has not been a systematic analysis of the abilities of sera from subjects with a C2 deficiency to opsonize S. pneumoniae. Hence, to investigate the role of the classical pathway in immunity to S. pneumoniae in more detail, flow cytometry assays of opsonization with C3b and the phagocytosis of three capsular serotypes of S. pneumoniae were performed using human sera depleted of the complement factor C1q or B or sera obtained from C2-deficient subjects. The results demonstrate that, in human serum, the classical pathway is vital for C3b-iC3b deposition onto cells of all three serotypes of S. pneumoniae and seems to be more important than the alternative pathway for phagocytosis. Compared to the results for sera from normal subjects, C3b-iC3b deposition and total anti-S. pneumoniae antibody activity levels in sera obtained from C2?/? subjects were reduced and the efficiency of phagocytosis of all three S. pneumoniae strains was impaired. Anticapsular antibody levels did not correlate with phagocytosis or C3b-iC3b deposition. These data confirm that the classical pathway is vital for complement-mediated phagocytosis of S. pneumoniae and demonstrate why subjects with a C2 deficiency have a marked increase in susceptibility to S. pneumoniae infections. PMID:18541650

Yuste, Jose; Sen, Ashwin; Truedsson, Lennart; Jönsson, Göran; Tay, Liang-Seah; Hyams, Catherine; Baxendale, Helen E.; Goldblatt, Fiona; Botto, Marina; Brown, Jeremy S.

2008-01-01

117

Outer Membrane Protein P5 Is Required for Resistance of Nontypeable Haemophilus influenzae to Both the Classical and Alternative Complement Pathways  

PubMed Central

The complement system is an important first line of defense against the human pathogen Haemophilus influenzae. To survive and propagate in vivo, H. influenzae has evolved mechanisms for subverting this host defense, most of which have been shown to involve outer surface structures, including lipooligosaccharide glycans and outer surface proteins. Bacterial defense against complement acts at multiple steps in the pathway by mechanisms that are not fully understood. Here we identify outer membrane protein P5 as an essential factor in serum resistance of both H. influenzae strain Rd and nontypeable H. influenzae (NTHi) clinical isolate NT127. P5 was essential for resistance of Rd and NT127 to complement in pooled human serum. Further investigation determined that P5 expression decreased cell surface binding of IgM, a potent activator of the classical pathway of complement, to both Rd and NT127. Additionally, P5 expression was required for NT127 to bind factor H (fH), an important inhibitor of alternative pathway (AP) activation. Collectively, the results obtained in this work highlight the ability of H. influenzae to utilize a single protein to perform multiple protective functions for evading host immunity. PMID:24478079

Rosadini, Charles V.; Ram, Sanjay

2014-01-01

118

Meningococcal group W-135 and Y capsular polysaccharides paradoxically enhance activation of the alternative pathway of complement.  

PubMed

Although capsular polysaccharide (CPS) is critical for meningococcal virulence, the molecular basis of alternative complement pathway (AP) regulation by meningococcal CPSs remains unclear. Using serum with only the AP active, the ability of strains to generate C3a (a measure of C3 activation) and subsequently deposit C3 fragments on bacteria was studied in encapsulated group A, B, C, W-135, and Y strains and their isogenic unencapsulated mutants. To eliminate confounding AP regulation by membrane-bound factor H (fH; AP inhibitor) and lipooligosaccharide sialic acid, the meningococcal fH ligands (fHbp and NspA) and lipooligosaccharide sialylation were deleted in all strains. Group A CPS expression did not affect C3a generation or C3 deposition. C3a generated by encapsulated and unencapsulated group B and C strains was similar, but CPS expression was associated with reduced C3 deposition, suggesting that these CPSs blocked C3 deposition on membrane targets. Paradoxically, encapsulated W-135 and Y strains (including the wild-type parent strains) enhanced C3 activation and showed marked C3 deposition as early as 10 min; at this time point C3 was barely activated by the unencapsulated mutants. W-135 and Y CPSs themselves served as a site for C3 deposition; this observation was confirmed using immobilized purified CPSs. Purified CPSs bound to unencapsulated meningococci, simulated findings with naturally encapsulated strains. These data highlight the heterogeneity of AP activation on the various meningococcal serogroups that may contribute to differences in their pathogenic mechanisms. PMID:21245150

Ram, Sanjay; Lewis, Lisa A; Agarwal, Sarika

2011-03-11

119

Complement and Periodontitis  

PubMed Central

Although the complement system is centrally involved in host defense, its overactivation or deregulation (e.g., due to inherent host genetic defects or due to pathogen subversion) may excessively amplify inflammation and contribute to immunopathology. Periodontitis is an oral infection-driven chronic inflammatory disease which exerts a systemic impact on health. This paper reviews evidence linking complement to periodontal inflammation and pathogenesis. Clinical and histological observations show a correlation between periodontal inflammatory activity and local complement activation. Certain genetic polymorphisms or deficiencies in specific complement components appear to predispose to increased susceptibility to periodontitis. Animal model studies and in vitro experiments indicate that periodontal bacteria can either inhibit or activate distinct components of the complement cascade. Porphyromonas gingivalis, a keystone species in periodontitis, subverts complement receptor 3 and C5a anaphylatoxin receptor signaling in ways that promote its adaptive fitness in the presence of non-productive inflammation. Overall, available evidence suggests that complement activation or subversion contributes to periodontal pathogenesis, although not all complement pathways or functions are necessarily destructive. Effective complement-targeted therapeutic intervention in periodontitis would require determining the precise roles of the various inductive or effector complement pathways. This information is essential as it may reveal which specific pathways need to be blocked to counteract microbial evasion and inflammatory pathology or, conversely, be enhanced to promote host immunity. PMID:20599785

Hajishengallis, George

2010-01-01

120

Complement system in zebrafish.  

PubMed

Zebrafish is recently emerging as a model species for the study of immunology and human diseases. Complement system is the humoral backbone of the innate immune defense, and our knowledge as such in zebrafish has dramatically increased in the recent years. This review summarizes the current research progress of zebrafish complement system. The global searching for complement components in genome database, together with published data, has unveiled the existence of all the orthologues of mammalian complement components identified thus far, including the complement regulatory proteins and complement receptors, in zebrafish. Interestingly, zebrafish complement components also display some distinctive features, such as prominent levels of extrahepatic expression and isotypic diversity of the complement components. Future studies should focus on the following issues that would be of special importance for understanding the physiological role of complement components in zebrafish: conclusive identification of complement genes, especially those with isotypic diversity; analysis and elucidation of function and mechanism of complement components; modulation of innate and adaptive immune response by complement system; and unconventional roles of complement-triggered pathways. PMID:24462834

Zhang, Shicui; Cui, Pengfei

2014-09-01

121

Infections of people with complement deficiencies and patients who have undergone splenectomy.  

PubMed

The complement system comprises several fluid-phase and membrane-associated proteins. Under physiological conditions, activation of the fluid-phase components of complement is maintained under tight control and complement activation occurs primarily on surfaces recognized as "nonself" in an attempt to minimize damage to bystander host cells. Membrane complement components act to limit complement activation on host cells or to facilitate uptake of antigens or microbes "tagged" with complement fragments. While this review focuses on the role of complement in infectious diseases, work over the past couple of decades has defined several important functions of complement distinct from that of combating infections. Activation of complement in the fluid phase can occur through the classical, lectin, or alternative pathway. Deficiencies of components of the classical pathway lead to the development of autoimmune disorders and predispose individuals to recurrent respiratory infections and infections caused by encapsulated organisms, including Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. While no individual with complete mannan-binding lectin (MBL) deficiency has been identified, low MBL levels have been linked to predisposition to, or severity of, several diseases. It appears that MBL may play an important role in children, who have a relatively immature adaptive immune response. C3 is the point at which all complement pathways converge, and complete deficiency of C3 invariably leads to severe infections, including those caused by meningococci and pneumococci. Deficiencies of the alternative and terminal complement pathways result in an almost exclusive predisposition to invasive meningococcal disease. The spleen plays an important role in antigen processing and the production of antibodies. Splenic macrophages are critical in clearing opsonized encapsulated bacteria (such as pneumococci, meningococci, and Escherichia coli) and intraerythrocytic parasites such as those causing malaria and babesiosis, which explains the fulminant nature of these infections in persons with anatomic or functional asplenia. Paramount to the management of patients with complement deficiencies and asplenia is educating patients about their predisposition to infection and the importance of preventive immunizations and seeking prompt medical attention. PMID:20930072

Ram, Sanjay; Lewis, Lisa A; Rice, Peter A

2010-10-01

122

Infections of People with Complement Deficiencies and Patients Who Have Undergone Splenectomy  

PubMed Central

Summary: The complement system comprises several fluid-phase and membrane-associated proteins. Under physiological conditions, activation of the fluid-phase components of complement is maintained under tight control and complement activation occurs primarily on surfaces recognized as “nonself” in an attempt to minimize damage to bystander host cells. Membrane complement components act to limit complement activation on host cells or to facilitate uptake of antigens or microbes “tagged” with complement fragments. While this review focuses on the role of complement in infectious diseases, work over the past couple of decades has defined several important functions of complement distinct from that of combating infections. Activation of complement in the fluid phase can occur through the classical, lectin, or alternative pathway. Deficiencies of components of the classical pathway lead to the development of autoimmune disorders and predispose individuals to recurrent respiratory infections and infections caused by encapsulated organisms, including Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. While no individual with complete mannan-binding lectin (MBL) deficiency has been identified, low MBL levels have been linked to predisposition to, or severity of, several diseases. It appears that MBL may play an important role in children, who have a relatively immature adaptive immune response. C3 is the point at which all complement pathways converge, and complete deficiency of C3 invariably leads to severe infections, including those caused by meningococci and pneumococci. Deficiencies of the alternative and terminal complement pathways result in an almost exclusive predisposition to invasive meningococcal disease. The spleen plays an important role in antigen processing and the production of antibodies. Splenic macrophages are critical in clearing opsonized encapsulated bacteria (such as pneumococci, meningococci, and Escherichia coli) and intraerythrocytic parasites such as those causing malaria and babesiosis, which explains the fulminant nature of these infections in persons with anatomic or functional asplenia. Paramount to the management of patients with complement deficiencies and asplenia is educating patients about their predisposition to infection and the importance of preventive immunizations and seeking prompt medical attention. PMID:20930072

Ram, Sanjay; Lewis, Lisa A.; Rice, Peter A.

2010-01-01

123

Human mannose-binding lectin inhibitor prevents myocardial injury and arterial thrombogenesis in a novel animal model.  

PubMed

Myocardial infarction and coagulation disorders are leading causes of disability and death in the world. An important role of the lectin complement pathway in myocardial infarction and coagulation has been demonstrated in mice genetically deficient in lectin complement pathway proteins. However, these studies are limited to comparisons between wild-type and deficient mice and lack the ability to examine reversal/inhibition of injury after disease establishment. We developed a novel mouse that expresses functional human mannose-binding lectin (MBL) 2 under the control of Mbl1 promoter. Serum MBL2 concentrations averaged approximately 3 ?g/mL in MBL2(+/+)Mbl1(-/-)Mbl2(-/-) [MBL2 knock in (KI)] mice. Serum MBL2 level in MBL2 KI mice significantly increased after 7 (8 ?g/mL) or 14 (9 ?g/mL) days of hyperglycemia compared to normoglycemic mice (P < 0.001). Monoclonal antibody 3F8 inhibited C3 deposition on mannan-coated plates in MBL2 KI, but not wild-type, mice. Myocardial ischemia/reperfusion in MBL2 KI mice revealed that 3F8 preserved cardiac function and decreased infarct size and fibrin deposition in a time-dependent manner. Furthermore, 3F8 prevented ferric chloride-induced occlusive arterial thrombogenesis in vivo. MBL2 KI mice represent a novel animal model that can be used to study the lectin complement pathway in acute and chronic models of human disease. Furthermore, these novel mice demonstrate the therapeutic window for MBL2 inhibition for effective treatment of disease and its complications. PMID:25482922

Pavlov, Vasile I; Tan, Ying S; McClure, Erin E; La Bonte, Laura R; Zou, Chenhui; Gorsuch, William B; Stahl, Gregory L

2015-02-01

124

Ataxia-Telangiectasia Group D Complementing Gene (ATDC) Promotes Lung Cancer Cell Proliferation by Activating NF-?B Pathway  

PubMed Central

Previous studies suggested Ataxia-telangiectasia group D complementing gene (ATDC) as an oncogene in many types of cancer. However, its expression and biological functions in non-small cell lung cancer (NSCLC) remain unclear. Herein, we investigated its expression pattern in 109 cases of human NSCLC samples by immunohistochemistry and found that ATDC was overexpressed in 62 of 109 NSCLC samples (56.88%). ATDC overexpression correlated with histological type (p<0.0001), tumor status (p?=?0.0227) and histological differentiation (p?=?0.0002). Next, we overexpressed ATDC in normal human bronchial epithelial cell line HBE and depleted its expression in NSCLC cell lines A549 and H1299. MTT and colony formation assay showed that ATDC overexpression promoted cell proliferation while its depletion inhibited cell growth. Furthermore, cell cycle analysis showed that ATDC overexpression decreased the percentage of cells in G1 phase and increased the percentage of cells in S phase, while ATDC siRNA treatment increased the G1 phase percentage and decreased the S phase percentage. Further study revealed that ATDC overexpression could up-regulate cyclin D1 and c-Myc expression in HBE cells while its depletion down-regulated cyclin D1 and c-Myc expression in A549 and H1299 cells. In addition, ATDC overexpression was also associated with an increased proliferation index, cyclin D1 and c-Myc expression in human NSCLC samples. Further experiments demonstrated that ATDC up-regulated cyclin D1 and c-Myc expression independent of wnt/?-catenin or p53 signaling pathway. Interestingly, ATDC overexpression increased NF-?B reporter luciferase activity and p-I?B protein level. Correspondingly, NF-?B inhibitor blocked the effect of ATDC on up-regulation of cyclin D1 and c-Myc. In conclusion, we demonstrated that ATDC could promote lung cancer proliferation through NF-?B induced up-regulation of cyclin D1 and c-Myc. PMID:23776433

Tang, Zhong-Ping; Dong, Qian-Ze; Cui, Quan-Zhe; Papavassiliou, Paulie; Wang, En-Di; Wang, En-Hua

2013-01-01

125

Transcription efficiency of different chicken mannose-binding lectin promoter alleles.  

PubMed

The serum collectin mannose-binding lectin (MBL) plays a major role in innate immunity by activation of the lectin complement pathway or by acting as an opsonin. The serum levels of human and animal MBL are associated with susceptibility to a wide range of infections, and the variation of MBL in serum is genetically determined. In the chicken, 14 single nucleotide polymorphisms (SNPs) have so far been found in the MBL promoter region. In this study, the transcription activity of a 670-bp promoter region covering all 14 SNPs from the four MBL promoter alleles A1 to A4 was assessed using a dual-luciferase assay. Of the analysed alleles, A1 showed the highest transcription activity although this allele is frequently found in chickens with low MBL mRNA expression. PMID:25186068

Kjćrup, R M; Dalgaard, T S; Norup, L R; Goto, R M; Miller, M M; Sřrensen, P; Juul-Madsen, H R

2014-12-01

126

Alterations in protein expression and complement resistance of pathogenic Naegleria amoebae.  

PubMed Central

Highly pathogenic strains of Naegleria fowleri activate the alternative complement pathway but are resistant to lysis. In contrast, weakly pathogenic and nonpathogenic Naegleria spp. activate the complement pathway and are readily lysed. The present study was undertaken to determine whether surface components on amoebae accounted for resistance to complement lysis. Enzymatic removal of surface components from highly pathogenic N. fowleri with phosphatidylinositol-specific phospholipase C or with endoglycosidase H increased the susceptibility of these amoebae to complement-mediated lysis. Similar treatment of nonpathogenic amoebae had no effect on susceptibility to complement. Tunicamycin treatment of highly and weakly pathogenic N. fowleri increased susceptibility to lysis by complement in a dose-related manner. Tunicamycin treatment did not alter the susceptibility of nonpathogenic amoebae to complement. Proteins of 234 and 47 kDa were detected in supernatant fluid from phosphatidylinositol-specific phospholipase C-treated highly pathogenic amoebae but not in supernatant fluid from phosphatidylinositol-specific phospholipase C-treated weakly pathogenic amoebae. Electrophoretic analysis of iodinated surface proteins of highly pathogenic N. fowleri revealed species of 89, 60, 44, and 28 kDa. Western immunoblots of lysates from surface-iodinated amoebae were stained with biotinylated concanavalin A or biotinylated Ulex europaeus agglutinin I. Surface proteins, identified in highly pathogenic amoebae by iodination, were shown to be glycoproteins by lectin analysis specific for the detection of mannose and fucose residues. Images PMID:1319405

Toney, D M; Marciano-Cabral, F

1992-01-01

127

Sundanese Complementation  

ERIC Educational Resources Information Center

The focus of this thesis is the description and analysis of clausal complementation in Sundanese, an Austronesian language spoken in Indonesia. The thesis examined a range of clausal complement types in Sundanese, which consists of (i) "yen/(wi)rehna" "that" complements, (ii) "pikeun" "for" complements,…

Kurniawan, Eri

2013-01-01

128

Combined Roles of Human IgG Subclass, Alternative Complement Pathway Activation, and Epitope Density in the Bactericidal Activity of Antibodies to Meningococcal Factor H Binding Protein  

PubMed Central

Meningococcal vaccines containing factor H binding protein (fHbp) are in clinical development. fHbp binds human fH, which enables the meningococcus to resist complement-mediated bacteriolysis. Previously, we found that chimeric human IgG1 mouse anti-fHbp monoclonal antibodies (MAbs) had human complement-mediated bactericidal activity only if the MAb inhibited fH binding. Since IgG subclasses differ in their ability to activate complement, we investigated the role of human IgG subclasses on antibody functional activity. We constructed chimeric MAbs in which three different murine fHbp-specific binding domains were each paired with human IgG1, IgG2, or IgG3. Against a wild-type group B isolate, all three IgG3 MAbs, irrespective of their ability to inhibit fH binding, had bactericidal activity that was >5-fold higher than the respective IgG1 MAbs, while the IgG2 MAbs had the least activity. Against a mutant with increased fHbp expression, the anti-fHbp MAbs elicited greater C4b deposition (classical pathway) and greater bactericidal activity than against the wild-type strain, and the IgG1 MAbs had similar or greater activity than the respective IgG3 MAbs. The bactericidal activity against both wild-type and mutant strains also was dependent, in part, on activation of the alternative complement pathway. Thus, at lower epitope density in the wild-type strain, the IgG3 anti-fHbp MAbs had the greatest bactericidal activity. At a higher epitope density in the mutant, the IgG1 MAbs had similar or greater bactericidal activity than the IgG3 MAbs, and the activity was less dependent on the inhibition of fH binding than at a lower epitope density. PMID:22064712

Giuntini, Serena; Reason, Donald C.

2012-01-01

129

Commercially available complement component-depleted sera are unexpectedly codepleted of ficolin-2.  

PubMed

The ficolins are a family of innate pattern recognition molecules that are known to bind acetylated compounds and activate complement through the association of mannose binding lectin (MBL)/ficolin-associated serine proteases (MASPs). Their importance has more recently become appreciated, as they have been shown to play a role in a variety of disease processes from infection to autoimmunity. While studying ficolin-2-mediated complement deposition on Streptococcus pneumoniae, we found that sera depleted of C1q or other complement components were also codepleted of ficolin-2 but not ficolin-1, ficolin-3, or MBL. MBL present in C1q-depleted sera was able to mediate complement deposition on Saccharomyces cerevisiae, suggesting the presence of MASPs. We found that complement was activated on pneumococci in C1q-depleted serum only after opsonization with exogenous recombinant ficolin-2 (rFicolin-2). Also, no complement deposition was observed in C1q-depleted serum when pneumococci were opsonized with rFicolin-2 mutated at its lysine-57 residue, where MASPs are known to associate. Thus, these depleted sera are a unique tool to study ficolin-2-mediated complement pathways; however, one should be aware that ficolin-2 is absent from complement component-depleted sera. PMID:25030054

Brady, Allison M; Geno, K Aaron; Dalecki, Alex G; Cheng, Xiaogang; Nahm, Moon H

2014-09-01

130

Commercially Available Complement Component-Depleted Sera Are Unexpectedly Codepleted of Ficolin-2  

PubMed Central

The ficolins are a family of innate pattern recognition molecules that are known to bind acetylated compounds and activate complement through the association of mannose binding lectin (MBL)/ficolin-associated serine proteases (MASPs). Their importance has more recently become appreciated, as they have been shown to play a role in a variety of disease processes from infection to autoimmunity. While studying ficolin-2-mediated complement deposition on Streptococcus pneumoniae, we found that sera depleted of C1q or other complement components were also codepleted of ficolin-2 but not ficolin-1, ficolin-3, or MBL. MBL present in C1q-depleted sera was able to mediate complement deposition on Saccharomyces cerevisiae, suggesting the presence of MASPs. We found that complement was activated on pneumococci in C1q-depleted serum only after opsonization with exogenous recombinant ficolin-2 (rFicolin-2). Also, no complement deposition was observed in C1q-depleted serum when pneumococci were opsonized with rFicolin-2 mutated at its lysine-57 residue, where MASPs are known to associate. Thus, these depleted sera are a unique tool to study ficolin-2-mediated complement pathways; however, one should be aware that ficolin-2 is absent from complement component-depleted sera. PMID:25030054

Brady, Allison M.; Geno, K. Aaron; Dalecki, Alex G.; Cheng, Xiaogang

2014-01-01

131

The role of complement in the pathogenesis of renal ischemia-reperfusion injury and fibrosis  

PubMed Central

The complement system is a major component of innate immunity and has been commonly identified as a central element in host defense, clearance of immune complexes, and tissue homeostasis. After ischemia-reperfusion injury (IRI), the complement system is activated by endogenous ligands that trigger proteolytic cleavage of complement components via the classical, lectin and/or alternative pathway. The result is the formation of terminal complement components C3a, C5a, and the membrane attack complex (C5b-9 or MAC), all of which play pivotal roles in the amplification of the inflammatory response, chemotaxis, neutrophil/monocyte recruitment and activation, and direct tubular cell injury. However, recent evidence suggests that complement activity transcends innate host defense and there is increasing data suggesting complement as a regulator in processes such as allo-immunity, stem cell differentiation, tissue repair, and progression to fibrosis. In this review, we discuss recent advances addressing the role of complement as a regulator of IRI and renal fibrosis after organ donation for transplantation. We will also briefly discuss currently approved therapies that target complement activity in kidney ischemia-reperfusion and transplantation. PMID:25383094

2014-01-01

132

Pulmonary alveolar type II epithelial cells synthesize and secrete proteins of the classical and alternative complement pathways.  

PubMed Central

The serum complement system is a major mediator of inflammation reactions. Two of the complement proteins, the third (C3) and fifth (C5) components, are precursors of potent phlogistic molecules, C3a and C5a. C5a has potent chemotactic activity and plays an active role in pulmonary inflammation. We present evidence suggesting that several complement proteins, including C5, are synthesized locally in the lung in alveolar type II epithelial cells. Lung tissue from normal mice synthesized and secreted C5 protein similar to the C5 protein in mouse serum, whereas lung tissue from C5-deficient mice did not. Lung tissues from both normal and C5-deficient mice synthesized C3. Rat lung tissue synthesized and secreted C5, as well as C2, C4, C3, and factor B. Cultures of type II cells (95% type II cells, 5% macrophages) regularly synthesized all these proteins. In contrast, cultures of macrophages alone synthesized large amounts of C2 and factor B, and in some experiments C3 and C4, but never C5. The C5 synthesized by the rat cells was slightly larger than serum C5 (200 kD compared with 180 kD) and was not processed to the two-chain molecule seen in serum. Rat lung tissue and purified type II cells contained C5 mRNA with the same molecular mass as the C5 mRNA in rat liver and in mouse lung and liver. Human type II cells also synthesized C5, as well as C2, C4, C3, and factor B. Human pulmonary macrophages synthesized only C2, factor B, and, in some experiments, C3. Synthesis of complement proteins in cells that line the alveolar wall may provide a local source of these proteins for inflammatory responses in the lung. Local synthesis of complement proteins could be regulated independently of the synthesis in the liver. Images PMID:2966814

Strunk, R C; Eidlen, D M; Mason, R J

1988-01-01

133

Epidermal growth factor receptor targeting IgG3 triggers complement-mediated lysis of decay-accelerating factor expressing tumor cells through the alternative pathway amplification loop.  

PubMed

Binding of C1q to target-bound IgG initiates complement-mediated lysis (CML) of pathogens, as well as of malignant or apoptotic cells, and thus constitutes an integral part of the innate immune system. Despite its prominent molecular flexibility and higher C1q binding affinity compared with human IgG1, IgG3 does not consistently promote superior CML. Hence the aim of this study was to investigate underlying molecular mechanisms of IgG1- and IgG3-driven complement activation using isotype variants of the therapeutic epidermal growth factor receptor (EGFR) Ab cetuximab. Both IgG1 and IgG3 Abs demonstrated similar EGFR binding and similar efficiency in Fab-mediated effector mechanisms. Whereas anti-EGFR-IgG1 did not promote CML of investigated target cells, anti-EGFR-IgG3 triggered significant CML of some, but not all tested cell lines. CML triggered by anti-EGFR-IgG3 negatively correlated with expression levels of the membrane-bound complement regulatory proteins CD55 and CD59, but not CD46. Notably, anti-EGFR-IgG3 promoted strong C1q and C3b, but relatively low C4b and C5b-9 deposition on analyzed cell lines. Furthermore, anti-EGFR-IgG3 triggered C4a release on all cells but failed to induce C3a and C5a release on CD55/CD59 highly expressing cells. RNA interference-induced knockdown or overexpression of membrane-bound complement regulatory proteins revealed CD55 expression to be a pivotal determinant of anti-EGFR-IgG3-triggered CML and to force a switch from classical complement pathway activation to C1q-dependent alternative pathway amplification. Together, these data suggest human anti-EGFR-IgG3, although highly reactive with C1q, to weakly promote assembly of the classical C3 convertase that is further suppressed in the presence of CD55, forcing human IgG3 to act mainly through the alternative pathway. PMID:24973443

Rösner, Thies; Lohse, Stefan; Peipp, Matthias; Valerius, Thomas; Derer, Stefanie

2014-08-01

134

Regulatory Components of the Alternative Complement Pathway in Endothelial Cell Cytoplasm, Factor H and Factor I, Are Not Packaged in Weibel-Palade Bodies  

PubMed Central

It was recently reported that factor H, a regulatory component of the alternative complement pathway, is stored with von Willebrand factor (VWF) in the Weibel-Palade bodies of endothelial cells. If this were to be the case, it would have therapeutic importance for patients with the atypical hemolytic-uremic syndrome that can be caused either by a heterozygous defect in the factor H gene or by the presence of an autoantibody against factor H. The in vivo Weibel-Palade body secretagogue, des-amino-D-arginine vasopressin (DDAVP), would be expected to increase transiently the circulating factor H levels, in addition to increasing the circulating levels of VWF. We describe experiments demonstrating that factor H is released from endothelial cell cytoplasm without a secondary storage site. These experiments showed that factor H is not stored with VWF in endothelial cell Weibel-Palade bodies, and is not secreted in response in vitro in response to the Weibel-Palade body secretagogue, histamine. Furthermore, the in vivo Weibel-Palade body secretagogue, DDAVP does not increase the circulating factor H levels concomitantly with DDAVP-induced increased VWF. Factor I, a regulatory component of the alternative complement pathway that is functionally related to factor H, is also located in endothelial cell cytoplasm, and is also not present in endothelial cell Weibel-Palade bodies. Our data demonstrate that the factor H and factor I regulatory proteins of the alternative complement pathway are not stored in Weibel-Palade bodies. DDAVP induces the secretion into human plasma of VWF —- but not factor H. PMID:25803806

Turner, Nancy A.; Sartain, Sarah E.; Hui, Shiu-Ki; Moake, Joel L.

2015-01-01

135

Heavy Chains of Inter Alpha Inhibitor (I?I) Inhibit the Human Complement System at Early Stages of the Cascade*  

PubMed Central

Inter alpha inhibitor (I?I) is an abundant serum protein consisting of three polypeptides: two heavy chains (HC1 and HC2) and bikunin, a broad-specificity Kunitz-type proteinase inhibitor. The complex is covalently held together by chondroitin sulfate but during inflammation I?I may interact with TNF-stimulated gene 6 protein (TSG-6), which supports transesterification of heavy chains to hyaluronan. Recently, I?I was shown to inhibit mouse complement in vivo and to protect from complement-mediated lung injury but the mechanism of such activity was not elucidated. Using human serum depleted from I?I, we found that I?I is not an essential human complement inhibitor as was reported for mice and that such serum has unaltered hemolytic activity. However, purified human I?I inhibited classical, lectin and alternative complement pathways in vitro when added in excess to human serum. The inhibitory activity was dependent on heavy chains but not bikunin and detected at the level of initiating molecules (MBL, properdin) in the lectin/alternative pathways or C4b in the classical pathway. Furthermore, I?I affected formation and assembly of the C1 complex and prevented assembly of the classical pathway C3-convertase. Presence and putative interactions with TSG-6 did not affect the ability of I?I to inhibit complement thus implicating I?I as a potentially important complement inhibitor once enriched onto hyaluronan moieties in the course of local inflammatory processes. In support of this, we found a correlation between I?I/HC-containing proteins and hemolytic activity of synovial fluid from patients suffering from rheumatoid arthritis. PMID:22528482

Okroj, Marcin; Holmquist, Emelie; Sjölander, Jonatan; Corrales, Leticia; Saxne, Tore; Wisniewski, Hans-Georg; Blom, Anna M.

2012-01-01

136

Recombinant human complement component C2 produced in a human cell line restores the classical complement pathway activity in-vitro: an alternative treatment for C2 deficiency diseases  

Microsoft Academic Search

BACKGROUND: Complement C2 deficiency is the most common genetically determined complete complement deficiency and is associated with a number of diseases. Most prominent are the associations with recurrent serious infections in young children and the development of systemic lupus erythematosus (SLE) in adults. The links with these diseases reflect the important role complement C2 plays in both innate immunity and

Paolo GV Martini; Lynette C Cook; Scott Alderucci; Angela W Norton; Dianna M Lundberg; Susan M Fish; Knut Langsetmo; Göran Jönsson; Christian Lood; Birgitta Gullstrand; Kate J Zaleski; Nancy Savioli; Jason Lottherand; Charles Bedard; John Gill; Michael F Concino; Michael W Heartlein; Lennart Truedsson; Jan L Powell; Arthur O Tzianabos

2010-01-01

137

Accelerated Tumor Growth Mediated by Sub-lytic Levels of Antibody-Induced Complement Activation is Associated with Activation of the PI3K/AKT Survival Pathway  

PubMed Central

Purpose We addressed the possibility that low levels of tumor cell bound antibodies targeting gangliosides might accelerate tumor growth. Experimental Design To test this hypothesis, we treated mice with a range of mAb doses against GM2, GD2, GD3 and CD20 after challenge with tumors expressing these antigens and tested the activity of the same mAbs in-vitro. We also explored the mechanisms behind the complement-mediated tumor growth acceleration that we observed and an approach to overcome it. Results Serologically detectable levels of IgM-mAb against GM2 are able to delay or prevent tumor growth of high GM2-expressing cell lines both in-vitro and in a SCID mouse model, while very low levels of this mAb resulted in slight but consistent acceleration of tumor growth in both settings. Surprisingly, this is not restricted to IgM antibodies targeting GM2 but consistent against IgG-mAb targeting GD3 as well. These findings were mirrored by in-vitro studies with antibodies against these antigens as well as GD2 and CD20 (with Rituxan), and shown to be complement-dependent in all cases. Complement-mediated accelerated growth of cultured tumor cell lines initiated by low mAb levels was associated with activation of the PI3K/AKT survival pathway and significantly elevated levels of both p-AKT and p-PRAS40. This complement-mediated PI3K-activation and accelerated tumor growth in-vitro and in-vivo are eliminated by PI3K-inhibitors NVP-BEZ235 and Wortmannin. These PI3K-inhibitors also significantly increased efficacy of high doses of these 4 mAbs. Conclusion Our findings suggest that manipulation of the PI3K/AKT pathway and its signaling network can significantly increase the potency of passively administered mAbs and vaccine-induced-antibodies targeting a variety of tumor-cell-surface-antigens. PMID:23833306

Wu, Xiaohong; Ragupathi, Govind; Panageas, Katherine; Hong, Feng; Livingston, Philip O.

2013-01-01

138

Sushi domain-containing protein 4 (SUSD4) inhibits complement by disrupting the formation of the classical C3 convertase.  

PubMed

Recently discovered Sushi domain-containing protein 4 (SUSD4) contains several Sushi or complement control protein domains; therefore, we hypothesized that it may act as complement inhibitor. Two isoforms of human SUSD4, fused to the Fc part of human IgG, were recombinantly expressed in Chinese hamster ovary (CHO) cells. The secreted soluble isoform of SUSD4 (SUSD4b) inhibited the classical and lectin complement pathways by 50% at a concentration of 0.5 ?M. This effect was due to the fact that 1 ?M SUSD4b inhibited the formation of the classical C3 convertase by 90%. The membrane-bound isoform (SUSD4a) inhibited the classical and alternative complement pathways when expressed on the surface of CHO cells but not when expressed as a soluble, truncated protein. In all functional studies, we used known complement inhibitors as positive controls, while Coxsackie adenovirus receptor, which has no effect on complement, expressed with Fc tag, was a negative control. We also studied the mRNA expression of both isoforms of SUSD4 in a panel of human tissues using quantitative PCR and primarily found SUSD4a in esophagus and brain, while SUSD4b was highly expressed in esophagus, ovary, and heart. Overall, our results show that SUSD4 is a novel complement inhibitor with restricted expression. PMID:23482636

Holmquist, Emelie; Okroj, Marcin; Nodin, Björn; Jirström, Karin; Blom, Anna M

2013-06-01

139

The C5 Convertase Is Not Required for Activation of the Terminal Complement Pathway in Murine Experimental Cerebral Malaria*  

PubMed Central

Cerebral malaria (CM) is the most severe manifestation of clinical malaria syndromes and has a high fatality rate especially in the developing world. Recent studies demonstrated that C5?/? mice are resistant to experimental CM (ECM) and that protection was due to the inability to form the membrane attack complex. Unexpectedly, we observed that C4?/? and factor B?/? mice were fully susceptible to disease, indicating that activation of the classical or alternative pathways is not required for ECM. C3?/? mice were also susceptible to ECM, indicating that the canonical C5 convertases are not required for ECM development and progression. Abrogation of ECM by treatment with anti-C9 antibody and detection of C5a in serum of C3?/? mice confirmed that C5 activation occurs in ECM independent of C5 convertases. Our data indicate that activation of C5 in ECM likely occurs via coagulation enzymes of the extrinsic protease pathway. PMID:22689574

Ramos, Theresa N.; Darley, Meghan M.; Weckbach, Sebastian; Stahel, Philip F.; Tomlinson, Stephen; Barnum, Scott R.

2012-01-01

140

The relative roles of fHbp, NspA and lipooligosaccharide sialylation in regulation of the alternative pathway of complement on meningococci  

PubMed Central

Neisseria meningitidis inhibits the alternative pathway (AP) of complement utilizing diverse mechanisms, including expression of capsule (select serogroups), Neisserial surface protein A (NspA), factor H binding protein (fHbp) and lipooligosaccharide (LOS) sialylation. The contribution of the latter three molecules in AP regulation in encapsulated meningococci was studied using isogenic mutants. When LOS was unsialylated, deleting NspA alone from group A strain A2594 (low fHbp/high NspA) significantly increased AP-mediated C3 deposition. C3 deposition further increased ~2-fold in a ?fHbp?NspA double mutant, indicating cooperative fHbp function. LOS sialylation of A2594 ?fHbp?NspA decreased the rate of C3 deposition, revealing AP inhibition by LOS sialic acid. Maximal C3 deposition on group B strain H44/76 (high fHbp/low NspA) occurred when all three molecules were absent; again, LOS sialylation attenuated the AP in the absence of both fHbp and NspA. When H44/76 LOS was unsialylated, both fHbp and NspA independently inhibited the AP. LOS sialylation enhanced binding of fH C-terminal domains 18–20 to C3 fragments deposited on bacteria. Interaction of meningococci with non-human complement is relevant for animal models and vaccine evaluation studies that employ non-human complement. Consistent with their human-specific fH binding, neither fHbp nor NspA regulated the rat AP. However, LOS sialylation inhibited the rat AP and, as with human serum, enhanced binding of rat fH to surface-bound C3. These data highlight the cooperative roles of meningococcal NspA and fHbp in regulating the human AP and broaden the molecular basis for LOS sialylation in AP regulation on meningococci in more than one animal species. PMID:22504643

Lewis, Lisa A.; Carter, Matthew; Ram, Sanjay

2012-01-01

141

CD21/35 Promotes Protective Immunity to S. pneumoniae through a Complement-Independent but CD19-Dependent Pathway that Regulates PD-1 Expression1  

PubMed Central

Humoral immunity to T cell-independent type 2 antigens (TI-2 Ag) is critical for protection against encapsulated bacteria such as Streptococcus pneumoniae. The CD21/35 receptor is thought to promote protective humoral immunity to encapsulated bacteria by enabling complement-decorated capsular polysaccharides to coligate the CD21/35-CD19 signaling complex with the B cell Ag receptor (BCR), thereby enhancing Ag-specific B cell activation. However, antibody responses to S. pneumoniae type 3 capsular polysaccharide (PPS-3) and other strong TI-2 Ags were significantly impaired in CD21/35?/?, but not C3?/? or C4?/? mice. B cells from CD21/35?/? mice expressed significantly higher levels of cell-surface CD19. CD21/35?/? B cells exhibited enhanced BCR-induced calcium responses and significantly higher expression of the inhibitory programmed death-1 (PD-1) receptor following immunization with a TI-2 Ag or BCR crosslinking. Reducing CD19 expression in CD21/35?/? mice normalized BCR-induced calcium responses, PD-1 induction, PPS-3-specific IgG3 responses, and restored protection during S. pneumoniae infection. PD-1 blockade also selectively rescued PPS-3-specific IgG3 responses in CD21/35?/? mice. Thereby, CD21/35 promotes protective humoral immunity to S. pneumoniae and other strong TI-2 Ags through a complement-independent pathway by negatively regulating CD19 expression and PD-1 induction. PMID:19710450

Haas, Karen M.; Poe, Jonathan C.; Tedder, Thomas F.

2013-01-01

142

Modulation of glycan detection on specific glycoproteins by lectin multimerization  

PubMed Central

Improved methods for studying glycans could spur significant advances in the understanding and application of glycobiology. The use of affinity reagents such as lectins and glycan-binding antibodies is a valuable complement to methods involving mass spectrometry and chromatography. Many lectins, however, are not useful as analytic tools due to low affinity in vitro. As an approach to increasing lectin avidity to targeted glycans, we tested the use of lectin multimerization. Several biotinylated lectins were linked together through streptavidin interactions. The binding of certain lectins for purified glycoproteins and glycoproteins captured directly out of biological solutions was increased using multimerization, resulting in the detection of lower concentrations of glycoprotein than possible using monomeric detection. The analysis of glycoproteins in plasma samples showed that the level of binding enhancement through multimerization was not equivalent across patient samples. Wheat germ agglutinin (WGA) reactive glycans on fibronectin and thrombospondin-5 were preferentially bound by multimers in pancreatic cancer patient samples relative to control samples, suggesting a cancer-associated change in glycan density that could be detected only through lectin multimerization. This strategy could lead to the more sensitive and informative detection of glycans in biological samples and a broader spectrum of lectins that are useful as analytical reagents. PMID:23286506

Cao, Zheng; Partyka, Katie; McDonald, Mitchell; Brouhard, Elizabeth; Hincapie, Marina; Brand, Randall E.; Hancock, William S.; Haab, Brian B.

2013-01-01

143

[Characteristic of the complement system in patients with ischemic heart disease with moderate and marked hemolysis after operations with cardiopulmonary bypass].  

PubMed

A study of the complement system in cardiosurgical patients with moderate (40 patients) and marked (18 patients) hemolysis after coronary artery bypass grafting in conditions of cardiopulmonary bypass was carried out. Before and after operation the content of D35+-, D55+-erythrocytes and reticulocytes in blood, free hemoglobin in blood plasma, indicators of the functional state of classical, lectin and alternative pathways of complement activation as well as concentration of its terminal complex in blood serum were analyzed. It was established that development of marked hemolysis was associated with higher (compared with moderate hemolysis) content of terminal complement complex and reticulocytes in blood before operation as well as deficiency of D55+- erythrocytes and low activity of alternative pathway. PMID:23548384

Chumakova, S P; Urazova, O I; Novitski?, V V; Shipulin, V M; Khokhlov, O A; Emel'ianova, T V; Mikha?lova, M A

2013-01-01

144

Surface-bound capsular polysaccharide of type Ia group B Streptococcus mediates C1 binding and activation of the classic complement pathway  

SciTech Connect

The role of surface-bound type Ia group B Streptococcus (GBS) capsular polysaccharide in anti-body-independent binding of C1 and activation of the classic component pathway was investigated. In a radiolabeled bacterial-polymorphonuclear leukocyte (PMN) association assay, a measure of bacterial opsonization, preincubation of /sup 3/H-type Ia GBS with purified F(ab')/sub 2/ to the organism blocked the association of the bacteria with PMN', and the inhibitory effect was dose dependent. The specificity of F(ab')/sub 2/ blocking was shown after adsorption of F(ab')/sub 2/ with type Ia polysaccharide-sensitized erythrocytes. Polysaccharide-adsorbed F(ab')/sub 2/ had a 70% decrease in ability to block the association of bacteria with PMN. Neuraminidase digestion removed 80% of the terminal sialic acid residues from the native polysaccharide. These neuraminidase-digested organisms had a 72% decrease in binding and transfer of purified C1 compared with non-enzyme-treated organisms. Type Ia capsular polysaccharide bound to sheep erythrocytes promoted classic complement pathway-mediated hemolysis of the cells. The role of C1 inhibitor (INH) in modulation of C1 activation by the organisms was investigated. The possibility existed that the C1 INH could be bound by the bacteria, allowing C1 activation to occur in the fluid phase. The inhibitor was purified from human serum, and its activity was measured before and after incubation with type Ia GBS. The organisms had no effect on C1 INH activity. Thus surface-bound capsular polysacchardie of type Ia GBS mediates C1 binding and classic pathway activation, and this does not involve the C1 INH.

Levy, N.J.; Kasper, D.L.

1986-06-01

145

Complement Test  

MedlinePLUS

... Louis, MO. Biology of the Immune System. The Merck Manual of Medical Information--Home Edition, Section 16. Immune ... http://www.merck.com . The Complement System. The Merck Manual of Diagnosis and Therapy, Section 12, Immunology; Allergic ...

146

Multiple roles of complement MASP-1 at the interface of innate immune response and coagulation.  

PubMed

MASP-1 is a versatile serine protease that cleaves a number of substrates in human blood. In recent years it became evident that besides playing a crucial role in complement activation MASP-1 also triggers other cascade systems and even cells to mount a more powerful innate immune response. In this review we summarize the latest discoveries about the diverse functions of this multi-faceted protease. Recent studies revealed that among MBL-associated serine proteases, MASP-1 is the one responsible for triggering the lectin pathway via its ability to rapidly autoactivate then cleave MASP-2, and possibly MASP-3. The crystal structure of MASP-1 explains its more relaxed substrate specificity compared to the related complement enzymes. Due to the relaxed specificity, MASP-1 interacts with the coagulation cascade and the kinin generating system, and it can also activate endothelial cells eliciting pro-inflammatory signaling. PMID:24935208

Dobó, József; Schroeder, Verena; Jenny, Lorenz; Cervenak, László; Závodszky, Péter; Gál, Péter

2014-10-01

147

CD45-mediated signaling pathway is involved in Rhizoctonia bataticola lectin (RBL)-induced proliferation and Th1/Th2 cytokine secretion in human PBMC  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer RBL, a potent mitogenic and complex N-glycan specific lectin binds to CD45 on PBMC. Black-Right-Pointing-Pointer RBL triggers CD45-mediated signaling involved in activation of p38MAPK and STAT-5. Black-Right-Pointing-Pointer Inhibition of CD45 PTPase signaling blocks RBL-induced ZAP70 phosphorylation. Black-Right-Pointing-Pointer RBL-CD45 mediated signaling is crucial for RBL-induced immunodulatory activities. -- Abstract: We earlier reported the mitogenic and immunostimulatory activities of Rhizoctonia bataticola lectin (RBL), purified from phytopathogenic fungus R. bataticola in human PBMC. The lectin demonstrates specificity towards glycoproteins containing complex N-glycans. Since CD45-protein tyrosine phosphatase that abundantly expresses N-glycans is important in T-cell signaling, the study aimed to investigate the involvement of CD45 in the immunomodulatory activities of RBL. Flowcytometry and confocal microscopy studies revealed that RBL exhibited binding to PBMC and colocalized with CD45. The binding was comparable in cells expressing different CD45 isoforms-RA, -RB and -RO. CD45 blocking antibody reduced the binding and proliferation of PBMC induced by RBL. CD45-PTPase inhibitor dephostatin inhibited RBL-induced proliferation, expression of CD25 and pZAP-70. RBL-induced secretion of Th1/Th2 cytokines were significantly inhibited in presence of dephostatin. Also, dephostatin blocked phosphorylation of p38MAPK and STAT-5 that was crucial for the biological functions of RBL. The study demonstrates the involvement of CD45-mediated signaling in RBL-induced PBMC proliferation and Th1/Th2 cytokine secretion through activation of p38MAPK and STAT-5.

Pujari, Radha [National Centre for Cell Science, Ganeshkhind, Pune 411007 (India)] [National Centre for Cell Science, Ganeshkhind, Pune 411007 (India); Eligar, Sachin M. [Department of Biochemistry, Karnatak University, Dharwad, 580003 Karnataka (India)] [Department of Biochemistry, Karnatak University, Dharwad, 580003 Karnataka (India); Kumar, Natesh [National Centre for Cell Science, Ganeshkhind, Pune 411007 (India)] [National Centre for Cell Science, Ganeshkhind, Pune 411007 (India); Nagre, Nagaraja N.; Inamdar, Shashikala R.; Swamy, Bale M. [Department of Biochemistry, Karnatak University, Dharwad, 580003 Karnataka (India)] [Department of Biochemistry, Karnatak University, Dharwad, 580003 Karnataka (India); Shastry, Padma, E-mail: padma@nccs.res.in [National Centre for Cell Science, Ganeshkhind, Pune 411007 (India)] [National Centre for Cell Science, Ganeshkhind, Pune 411007 (India)

2012-03-23

148

Inhibition of the Alternative Pathway of Nonhuman Infant Complement by Porin B2 Contributes to Virulence of Neisseria meningitidis in the Infant Rat Model  

PubMed Central

Neisseria meningitidis utilizes capsular polysaccharide, lipooligosaccharide (LOS) sialic acid, factor H binding protein (fHbp), and neisserial surface protein A (NspA) to regulate the alternative pathway (AP) of complement. Using meningococcal mutants that lacked all four of the above-mentioned molecules (quadruple mutants), we recently identified a role for PorB2 in attenuating the human AP; inhibition was mediated by human fH, a key downregulatory protein of the AP. Previous studies showed that fH downregulation of the AP via fHbp or NspA is specific for human fH. Here, we report that PorB2-expressing quadruple mutants also regulate the AP of baby rabbit and infant rat complement. Blocking a human fH binding region on PorB2 of the quadruple mutant of strain 4243 with a chimeric protein that comprised human fH domains 6 and 7 fused to murine IgG Fc enhanced AP-mediated baby rabbit C3 deposition, which provided evidence for an fH-dependent mechanism of nonhuman AP regulation by PorB2. Using isogenic mutants of strain H44/76 that differed only in their PorB molecules, we confirmed a role for PorB2 in resistance to killing by infant rat serum. The PorB2-expressing strain also caused higher levels of bacteremia in infant rats than its isogenic PorB3-expressing counterpart, thus providing a molecular basis for increased survival of PorB2 isolates in this model. These studies link PorB2 expression with infection of infant rats, which could inform the choice of meningococcal strains for use in animal models, and reveals, for the first time, that PorB2-expressing strains of N. meningitidis regulate the AP of baby rabbits and rats. PMID:24686052

Vu, David M.; Granoff, Dan M.; Ram, Sanjay

2014-01-01

149

Activation of the Classical Complement Pathway by Bacillus anthracis is the Primary Mechanism for Spore Phagocytosis and Involves the Spore Surface Protein BclA§  

PubMed Central

Interactions between spores of Bacillus anthracis and macrophages are critical for the development of anthrax infections, as spores are thought to utilize macrophages as vehicles to disseminate in the host. Here we report a novel mechanism for phagocytosis of B. anthracis spores. Murine macrophage-like cell line RAW264.7, bone marrow derived macrophages and primary peritoneal macrophages from mice were used. The results indicated that activation of the classical complement pathway (CCP) was a primary mechanism for spore phagocytosis. Phagocytosis was significantly reduced in the absence of C1q or C3. C3 fragments were found deposited on the spore surface and the deposition was dependent on C1q and Ca2+. C1q recruitment to the spore surface was mediated by the spore surface protein BclA, as recombinant BclA bound directly and specifically to C1q and inhibited C1q binding to spores in a dose-dependent manner. C1q binding to spores lacking BclA (?bclA) was also significantly reduced compared to wild type spores. In addition, deposition of both C3 and C4 as well as phagocytosis of spores were significantly reduced when BclA was absent but were not reduced in the absence of IgG, suggesting that BclA but not IgG is important in these processes. Taken together, these results support a model in which spores actively engage CCP primarily through BclA interaction with C1q, leading to CCP activation and opsonophagocytosis of spores in an IgG-independent manner. These findings are likely to have significant implications on B. anthracis pathogenesis and microbial manipulation of complement. PMID:22442442

Gu, Chunfang; Jenkins, Sarah A.; Xue, Qiong; Xu, Yi

2012-01-01

150

An autosomal dominant gene regulates the extent of 9-O-acetylation of murine erythrocyte sialic acids. A probable explanation for the variation in capacity to activate the human alternate complement pathway  

PubMed Central

Nydegger et al. (4) have reported that the difference in susceptibility of erythrocytes from different inbred murine strains to lysis by the human alternate complement pathway is determined by an autosomal locus. We have found a good correlation between the degree of O-acetylation of the erythrocyte sialic acid residues and the susceptibility to complement lysis, whereas there was no correlation between total erythrocyte sialic acid content and complement sensitivity. The major O- acetylated species in all the murine strains is 9-O-acetyl-N- acetylneuraminic acid. We propose that the autosomal dominant locus, which determines complement sensitivity, acts by influencing the extent of 9-O-acetylation of the erythrocyte sialic acid residues. By using recombinant inbred strains, we determined that this genetic locus is probably located on chromosome 9. The nature of the gene product remains unknown. PMID:7411019

1980-01-01

151

Microglia, Alzheimer's Disease, and Complement  

PubMed Central

Microglia, the immune cell of the brain, are implicated in cascades leading to neuronal loss and cognitive decline in Alzheimer's disease (AD). Recent genome-wide association studies have indicated a number of risk factors for the development of late-onset AD. Two of these risk factors are an altered immune response and polymorphisms in complement receptor 1. In view of these findings, we discuss how complement signalling in the AD brain and microglial responses in AD intersect. Dysregulation of the complement cascade, either by changes in receptor expression, enhanced activation of different complement pathways or imbalances between complement factor production and complement cascade inhibitors may all contribute to the involvement of complement in AD. Altered complement signalling may reduce the ability of microglia to phagocytose apoptotic cells and clear amyloid beta peptides, modulate the expression by microglia of complement components and receptors, promote complement factor production by plaque-associated cytokines derived from activated microglia and astrocytes, and disrupt complement inhibitor production. The evidence presented here indicates that microglia in AD are influenced by complement factors to adopt protective or harmful phenotypes and the challenge ahead lies in understanding how this can be manipulated to therapeutic advantage to treat late onset AD. PMID:22957298

Crehan, Helen; Hardy, John; Pocock, Jennifer

2012-01-01

152

Complement Activation by Merozoite Antigens of Plasmodium falciparum  

PubMed Central

Background Complement (C) is a crucial part of the innate immune system and becomes over activated during malaria, resulting in depletion of C components, especially those for lectin pathway (LP), thereby compromising the host's innate defense. In this study, involvement of P. falciparum antigens in C activation was investigated. Methods A highly synchronous culture of the Dd2 clone of P. falciparum was established in a serum free medium. Supernatants harvested from rings, trophozoites and schizonts at various parasite densities were tested for ability to activate C by quantifying amount of C3b deposited on erythrocytes (E). Uninfected sham culture was used as control. Remnants of each C pathway were determined using Wieslab complement System Screenkit (Euro-diagnostica, Sweden). To identify MBL binding antigens of LP, culture supernatants were added to MBL sepharose columns and trapped antigens eluted with increasing concentrations of EDTA (10 mM, 50 mM and 100 mM) and then desalted before being tested for ability to activate C. The EDTA eluate with highest activity was run on a polyacrylamide gel and silver stained proteins analyzed by mass spectroscopy. Results Antigens released by P. falciparum growing in culture activated C leading to C3b deposition on E. Maximal activation at 7% parasitemia was associated with schizont stage (36.7%) compared to 22% for rings, 21% for trophozoites and 3% for sham culture. All the three pathways of C were activated, with highest activation being for the alternative pathway (only 6% of C activation potential remained), 65% for classiical and 43% for the LP. Seven MBL binding merozoite proteins were identified by mass spectrometry in the 50 mM EDTA eluate. Conclusions MBL binding merozoite adhesins with ability to activate C pathway were identified. The survival advantage for such pronounced C activation is unclear, but opsonisation could facilitate recognition and invasion of E. PMID:25144772

Korir, Jackson C.; Nyakoe, Nancy K.; Awinda, George; Waitumbi, John N.

2014-01-01

153

Association of complement receptor 2 polymorphisms with innate resistance to HIV-1 infection.  

PubMed

HIV-1 induces activation of complement through the classical and lectin pathways. However, the virus incorporates several membrane-bound or soluble regulators of complement activation (RCA) that inactivate complement. HIV-1 can also use the complement receptors (CRs) for complement-mediated antibody-dependent enhancement of infection (?-ADE). We hypothesize that hypofunctional polymorphisms in RCA or CRs may protect from HIV-1 infection. For this purpose, 139 SNPs located in 19 RCA and CRs genes were genotyped in a population of 201 Spanish HIV-1-exposed seronegative individuals (HESN) and 250 HIV-1-infected patients. Two SNPs were associated with infection susceptibility, rs1567190 in CR2 (odds ratio (OR)=2.27, P=1 × 10(-4)) and rs2842704 in C4BPA (OR=2.11, P=2 × 10(-4)). To replicate this finding, we analyzed a cohort of Italian, sexually HESN individuals. Although not significant (P=0.25, OR=1.57), similar genotypic proportions were obtained for the CR2 marker rs1567190. The results of the two association analyses were combined through a random effect meta-analysis, with a significant P-value of 2.6x10(-5) (OR=2.07). Furthermore, we found that the protective CR2 genotype is correlated with lower levels CR2 mRNA as well as differences in the ratio of the long and short CR2 isoforms. PMID:25569262

Herrero, R; Real, L M; Rivero-Juárez, A; Pineda, J A; Camacho, Á; Macías, J; Laplana, M; Konieczny, P; Márquez, F J; Souto, J C; Soria, J M; Saulle, I; Lo Caputo, S; Biasin, M; Rivero, A; Fibla, J; Caruz, A

2015-03-01

154

Effect of the extract of the tamarind (Tamarindus indica) fruit on the complement system: studies in vitro and in hamsters submitted to a cholesterol-enriched diet.  

PubMed

This work evaluated a crude hydroalcoholic extract (ExT) from the pulp of the tamarind (Tamarindus indica) fruit as a source of compounds active on the complement system (CS) in vitro. ExT, previously characterized by other authors, had time and concentration dependent effects on the lytic activity of the CS. The activity of 0.8 mg/mL of the extract on the classical/lectin pathways (CP/LP) increased after 30 min of pre-incubation, while that of the alternative pathway (AP) decreased after 15 min at 1mg/mL. Since the CS is a mediator of inflammation, studies were also made in vivo, taking advantage of a model of hypercholesterolemia in hamsters to investigate the role of CS in the phase preceding the inflammatory process of atherosclerosis. Hamsters submitted to a diet rich in cholesterol showed increased lytic activity of the CP/LP and AP after 45 days. The activity levels of C2 and factor B components on respectively, classical/lectin and alternative pathways of the CS also increased. Early events cooperating to trigger the process of atherosclerotic lesions are not completely understood, and these alterations of complement may participate in these events. When treatment with a diet rich in cholesterol was associated to the furnishing of ExT, evaluation of complement components and complement lytic activity showed values similar to those of the controls, showing that treatment with ExT blocked the increase of complement activity caused by the cholesterol-rich diet. By itself, ExT had no effect on the complement system in vivo. ExT activity on the CS may be of interest for therapy and research purposes. PMID:17383788

Landi Librandi, Ana Paula; Chrysóstomo, Taís Nader; Azzolini, Ana Elisa C S; Recchia, Carem Gledes Vargas; Uyemura, Sérgio Akira; de Assis-Pandochi, Ana Isabel

2007-08-01

155

Mannose-Binding Lectin Deficiency and Respiratory Tract Infection  

Microsoft Academic Search

Mannose-binding lectin (MBL) is an innate immune system pattern recognition protein that kills a wide range of pathogenic microbes through complement activation. A substantial proportion of all human populations studied to date have MBL deficiency due to MBL2 polymorphisms, which potentially increases susceptibility to infectious disease. MBL binds numerous respiratory pathogens but the capsule of Streptococcus pneumoniae abrogates its efficient

Damon P. Eisen

2010-01-01

156

N-glycoprotein enrichment by lectin affinity chromatography.  

PubMed

Lectins are proteins that bind to sugars with varying specificities and several have been identified that show differential binding to structurally variable glycans attached to glycoproteins. Consequently, lectin affinity chromatography represents a valuable tool for glycoproteome studies, allowing enrichment of glycoproteins in samples prior to their identification by mass spectrometry (MS). From the perspective of plant scientists, lectin enrichment has proven useful for studies of the proteomes of the secretory pathways and cell wall, due to the high proportion of constituent proteins that are glycosylated. This chapter outlines a strategy to generate samples enriched with glycoproteins from bulk plant tissues prior to further characterization by MS, or other techniques. PMID:24136552

Ruiz-May, Eliel; Catalá, Carmen; Rose, Jocelyn K C

2014-01-01

157

Lectin purified from Musca domestica pupa up-regulates NO and iNOS production via TLR4/NF-?B signaling pathway in macrophages.  

PubMed

The present study reported that nitric oxide (NO) was up-regulated by the induction of lectin purified from Musca domestica pupa (MPL) in macrophages without cytotoxicity. The mRNA expression and protein secretion of inducible nitric oxide synthase (iNOS) were strongly induced by MPL treatments. Subsequent investigation revealed that the nuclear factor-?B (NF-?B) inhibitory ?B (I?B) in endochylema was inhibited and NF-?B translocated into the nucleus after MPL treatment. Meanwhile, the IKK? was strongly induced and the production of the toll-like receptor 4 (TLR4) was significantly up-regulated. Moreover, MPL increased NO production via inducing the expression of iNOS through the activation of NF-?B, which suggested that MPL probably acted as an activating agent of the NF-?B activation. PMID:21168541

Cao, Xiaohong; Zhou, Minghui; Wang, Chunling; Hou, Lihua; Zeng, Bin

2011-04-01

158

A Serine Protease Isolated from the Bristles of the Amazonic Caterpillar, Premolis semirufa, Is a Potent Complement System Activator  

PubMed Central

Background The caterpillar of the moth Premolis semirufa, commonly named pararama, is found in the Brazilian Amazon region. Accidental contact with the caterpillar bristles causes an intense itching sensation, followed by symptoms of an acute inflammation, which last for three to seven days after the first incident. After multiple accidents a chronic inflammatory reaction, called “Pararamose”, characterized by articular synovial membrane thickening with joint deformities common to chronic synovitis, frequently occurs. Although complement mediated inflammation may aid the host defense, inappropriate or excessive activation of the complement system and generation of anaphylatoxins can lead to inflammatory disorder and pathologies. The aim of the present study was to evaluate, in vitro, whether the Premolis semirufa’s bristles extract could interfere with the human complement system. Results The bristles extract was able to inhibit the haemolytic activity of the alternative pathway, as well as the activation of the lectin pathway, but had no effect on the classical pathway, and this inhibition seemed to be caused by activation and consumption of complement components. The extract induced the production of significant amounts of all three anaphylatoxins, C3a, C4a and C5a, promoted direct cleavage of C3, C4 and C5 and induced a significant generation of terminal complement complexes in normal human serum. By using molecular exclusion chromatography, a serine protease of 82 kDa, which activates complement, was isolated from P. semirufa bristles extract. The protease, named here as Ps82, reduced the haemolytic activity of the alternative and classical pathways and inhibited the lectin pathway. In addition, Ps82 induced the cleavage of C3, C4 and C5 and the generation of C3a and C4a in normal human serum and it was capable to cleave human purified C5 and generate C5a. The use of Phenanthroline, metalloprotease inhibitor, in the reactions did not significantly interfere with the activity of the Ps82, whereas the presence of PMSF, serine protease inhibitor, totally blocked the activity. Conclusion These data show that a serine protease present in the Premolis semirufa’s bristles extract has the ability to activate the complement system, which may contribute to the inflammatory process presented in humans after envenomation. PMID:25760458

Villas Boas, Isadora Maria; Pidde-Queiroz, Giselle; Magnoli, Fabio Carlos; Gonçalves-de-Andrade, Rute M.; van den Berg, Carmen W.; Tambourgi, Denise V.

2015-01-01

159

C3 dysregulation due to factor H deficiency is mannan-binding lectin-associated serine proteases (MASP)-1 and MASP-3 independent in vivo  

PubMed Central

Uncontrolled activation of the complement alternative pathway is associated with complement-mediated renal disease. Factor B and factor D are essential components of this pathway, while factor H (FH) is its major regulator. In complete FH deficiency, uncontrolled C3 activation through the alternative pathway results in plasma C3 depletion and complement-mediated renal disease. These are dependent on factor B. Mannan-binding lectin-associated serine proteases 1 and 3 (MASP-1, MASP-3) have been shown recently to contribute to alternative pathway activation by cleaving pro-factor D to its active form, factor D. We studied the contribution of MASP-1 and MASP-3 to uncontrolled alternative pathway activation in experimental complete FH deficiency. Co-deficiency of FH and MASP-1/MASP-3 did not ameliorate either the plasma C3 activation or glomerular C3 accumulation in FH-deficient mice. Our data indicate that MASP-1 and MASP-3 are not essential for alternative pathway activation in complete FH deficiency. PMID:24279761

Ruseva, M M; Takahashi, M; Fujita, T; Pickering, M C

2014-01-01

160

Mannose-binding lectin and ficolin-2 do not influence humoral immune response to hepatitis B vaccine  

PubMed Central

Background Host genetics appear to be an important factor in the failure to generate a protective immune response after hepatitis B (HBV) vaccination. Mannose-binding lectin (MBL) and ficolin-2 (FCN2), two pattern recognition receptors of the lectin pathway of complement, influence the clinical outcome of HBV, and MBL deficiency has been shown to augment the humoral response to HBV vaccination in several experimental models. Here, we investigated the association of MBL and FCN2 with the humoral response to HBV vaccination in a candidate gene and functional study. Patients and methods A post hoc analysis of a prospective, interventional HBV vaccination study among human immunodeficiency virus type 1 (HIV-1) uninfected individuals in Kenya was conducted. Serum levels and polymorphisms of MBL and FCN2 were analysed in relation to the immune response to HBV vaccination. Results Protective hepatitis B surface antibody levels (?10 mIU/ml) were evident in 251/293 (85.7%) individuals. Median MBL and FCN2 levels were similar in responders vs. non-responders with a weak trend towards lower median MBL levels in non-responders (1.0 vs. 1.6 ?g/ml, p=0.1). Similarly, there was no difference in four MBL and six FCN2 polymorphisms analysed in the two groups with the exception of an increased frequency of a homozygous MBL codon 57 mutation in non-responders (4 (9.5%) vs. 8 (3.2%), p=0.05) corresponding to lower MBL levels. Results were similar after adjusting for age and sex. Conclusions Our study does not support a prominent role of the lectin pathway of complement in general and MBL and FCN2 in particular in the humoral immune response to HBV vaccination in African adults. PMID:25024112

Osthoff, Michael; Irungu, Elizabeth; Ngure, Kenneth; Mugo, Nelly; Thomas, Katherine K.; Baeten, Jared M.; Eisen, Damon P

2015-01-01

161

Structural and functional diversity of the lectin repertoire in teleost fish: Relevance to innate and adaptive immunity  

PubMed Central

Protein–carbohydrate interactions mediated by lectins have been recognized as key components of innate immunity in vertebrates and invertebrates, not only for recognition of potential pathogens, but also for participating in downstream effector functions, such as their agglutination, immobilization, and complement-mediated opsonization and killing. More recently, lectins have been identified as critical regulators of mammalian adaptive immune responses. Fish are endowed with virtually all components of the mammalian adaptive immunity, and are equipped with a complex lectin repertoire. In this review, we discuss evidence suggesting that: (a) lectin repertoires in teleost fish are highly diversified, and include not only representatives of the lectin families described in mammals, but also members of lectin families described for the first time in fish species; (b) the tissue-specific expression and localization of the diverse lectin repertoires and their molecular partners is consistent with their distinct biological roles in innate and adaptive immunity; (c) although some lectins may bind endogenous ligands, others bind sugars on the surface of potential pathogens; (d) in addition to pathogen recognition and opsonization, some lectins display additional effector roles, such as complement activation and regulation of immune functions; (e) some lectins that recognize exogenous ligands mediate processes unrelated to immunity: they may act as anti-freeze proteins or prevent polyspermia during fertilization. PMID:21896283

Vasta, Gerardo R.; Nita-Lazar, Mihai; Giomarelli, Barbara; Ahmed, Hafiz; Du, Shaojun; Cammarata, Matteo; Parrinello, Nicolň; Bianchet, Mario A.; Amzel, L. Mario

2012-01-01

162

Model-Driven Redox Pathway Manipulation for Improved Isobutanol Production in Bacillus subtilis Complemented with Experimental Validation and Metabolic Profiling Analysis  

PubMed Central

To rationally guide the improvement of isobutanol production, metabolic network and metabolic profiling analysis were performed to provide global and profound insights into cell metabolism of isobutanol-producing Bacillus subtilis. The metabolic flux distribution of strains with different isobutanol production capacity (BSUL03, BSUL04 and BSUL05) drops a hint of the importance of NADPH on isobutanol biosynthesis. Therefore, the redox pathways were redesigned in this study. To increase NADPH concentration, glucose-6-phosphate isomerase was inactivated (BSUL06) and glucose-6-phosphate dehydrogenase was overexpressed (BSUL07) successively. As expected, NADPH pool size in BSUL07 was 4.4-fold higher than that in parental strain BSUL05. However, cell growth, isobutanol yield and production were decreased by 46%, 22%, and 80%, respectively. Metabolic profiling analysis suggested that the severely imbalanced redox status might be the primary reason. To solve this problem, gene udhA of Escherichia coli encoding transhydrogenase was further overexpressed (BSUL08), which not only well balanced the cellular ratio of NAD(P)H/NAD(P)+, but also increased NADH and ATP concentration. In addition, a straightforward engineering approach for improving NADPH concentrations was employed in BSUL05 by overexpressing exogenous gene pntAB and obtained BSUL09. The performance for isobutanol production by BSUL09 was poorer than BSUL08 but better than other engineered strains. Furthermore, in fed-batch fermentation the isobutanol production and yield of BSUL08 increased by 11% and 19%, up to the value of 6.12 g/L and 0.37 C-mol isobutanol/C-mol glucose (63% of the theoretical value), respectively, compared with parental strain BSUL05. These results demonstrated that model-driven complemented with metabolic profiling analysis could serve as a useful approach in the strain improvement for higher bio-productivity in further application. PMID:24705866

Qi, Haishan; Li, Shanshan; Zhao, Sumin; Huang, Di; Xia, Menglei; Wen, Jianping

2014-01-01

163

Lectin-Dependent Enhancement of Ebola Virus Infection via Soluble and Transmembrane C-type Lectin Receptors  

PubMed Central

Mannose-binding lectin (MBL) is a key soluble effector of the innate immune system that recognizes pathogen-specific surface glycans. Surprisingly, low-producing MBL genetic variants that may predispose children and immunocompromised individuals to infectious diseases are more common than would be expected in human populations. Since certain immune defense molecules, such as immunoglobulins, can be exploited by invasive pathogens, we hypothesized that MBL might also enhance infections in some circumstances. Consequently, the low and intermediate MBL levels commonly found in human populations might be the result of balancing selection. Using model infection systems with pseudotyped and authentic glycosylated viruses, we demonstrated that MBL indeed enhances infection of Ebola, Hendra, Nipah and West Nile viruses in low complement conditions. Mechanistic studies with Ebola virus (EBOV) glycoprotein pseudotyped lentiviruses confirmed that MBL binds to N-linked glycan epitopes on viral surfaces in a specific manner via the MBL carbohydrate recognition domain, which is necessary for enhanced infection. MBL mediates lipid-raft-dependent macropinocytosis of EBOV via a pathway that appears to require less actin or early endosomal processing compared with the filovirus canonical endocytic pathway. Using a validated RNA interference screen, we identified C1QBP (gC1qR) as a candidate surface receptor that mediates MBL-dependent enhancement of EBOV infection. We also identified dectin-2 (CLEC6A) as a potentially novel candidate attachment factor for EBOV. Our findings support the concept of an innate immune haplotype that represents critical interactions between MBL and complement component C4 genes and that may modify susceptibility or resistance to certain glycosylated pathogens. Therefore, higher levels of native or exogenous MBL could be deleterious in the setting of relative hypocomplementemia which can occur genetically or because of immunodepletion during active infections. Our findings confirm our hypothesis that the pressure of infectious diseases may have contributed in part to evolutionary selection of MBL mutant haplotypes. PMID:23573288

Lear, Calli; Chen, Li; Yantosca, L. Michael; Scully, Corinne; Sarraju, Ashish; Sokolovska, Anna; Zariffard, M. Reza; Eisen, Damon P.; Mungall, Bruce A.; Kotton, Darrell N.; Omari, Amel; Huang, I-Chueh; Farzan, Michael; Takahashi, Kazue; Stuart, Lynda; Stahl, Gregory L.; Ezekowitz, Alan B.; Spear, Gregory T.; Olinger, Gene G.; Schmidt, Emmett V.; Michelow, Ian C.

2013-01-01

164

Engineering complement activation on polypropylene sulfide vaccine nanoparticles  

E-print Network

moieties via the lectin pathway or IgG opsonization with C1q via the classical pathway. A third pathway. The anaphylatoxin and chemoattractant C3a [2] promotes rapid clearance of C3b-opsonized pathogens by invading

165

Lectins with anti-HIV activity: a review.  

PubMed

Lectins including flowering plant lectins, algal lectins, cyanobacterial lectins, actinomycete lectin, worm lectins, and the nonpeptidic lectin mimics pradimicins and benanomicins, exhibit anti-HIV activity. The anti-HIV plant lectins include Artocarpus heterophyllus (jacalin) lectin, concanavalin A, Galanthus nivalis (snowdrop) agglutinin-related lectins, Musa acuminata (banana) lectin, Myrianthus holstii lectin, Narcissus pseudonarcissus lectin, and Urtica diocia agglutinin. The anti-HIV algal lectins comprise Boodlea coacta lectin, Griffithsin, Oscillatoria agardhii agglutinin. The anti-HIV cyanobacterial lectins are cyanovirin-N, scytovirin, Microcystis viridis lectin, and microvirin. Actinohivin is an anti-HIV actinomycete lectin. The anti-HIV worm lectins include Chaetopterus variopedatus polychaete marine worm lectin, Serpula vermicularis sea worm lectin, and C-type lectin Mermaid from nematode (Laxus oneistus). The anti-HIV nonpeptidic lectin mimics comprise pradimicins and benanomicins. Their anti-HIV mechanisms are discussed. PMID:25569520

Akkouh, Ouafae; Ng, Tzi Bun; Singh, Senjam Sunil; Yin, Cuiming; Dan, Xiuli; Chan, Yau Sang; Pan, Wenliang; Cheung, Randy Chi Fai

2015-01-01

166

Lectins: production and practical applications  

PubMed Central

Lectins are proteins found in a diversity of organisms. They possess the ability to agglutinate erythrocytes with known carbohydrate specificity since they have at least one non-catalytic domain that binds reversibly to specific monosaccharides or oligosaccharides. This articles aims to review the production and practical applications of lectins. Lectins are isolated from their natural sources by chromatographic procedures or produced by recombinant DNA technology. The yields of animal lectins are usually low compared with the yields of plant lectins such as legume lectins. Lectins manifest a diversity of activities including antitumor, immunomodulatory, antifungal, HIV-1 reverse transcriptase inhibitory, and anti-insect activities, which may find practical applications. A small number of lectins demonstrate antibacterial and anti-nematode activities. PMID:20890754

2010-01-01

167

Defective activities, but not secretions, resulting from gene point mutations of human mannan-binding lectin  

PubMed Central

Human mannan-binding lectin (MBL) plays a pivotal role in innate immunity. Substantial literature supports the belief that three point mutations, CGT52TGT, GGC54GAC and GGA57GAA, in the collagen-like region (CLR) of the human MBL gene, are associated with increased susceptibility to infection, autoimmunity and carcinogenesis. To investigate the mechanisms of MBL deficiency, human wild-type and three variant MBL genes were expressed in COS-7 and Chinese hamster ovary (CHO) cells. Results showed that no apparent differences were found among the levels of gene transcription and protein secretion of four forms of MBL. However, the degree of oligomerization of variant forms of MBL was found to be much lower than that of recombinant human wild-type MBL. The ability of variant MBL proteins to bind mannan was much weaker than that of the wild-type MBL protein, and the MBL variants failed to effectively activate the complement lectin pathway. These data suggested that a lower order oligomer, but not decreased plasma levels of MBL, may be the main result of MBL gene mutations and may be associated with immunodeficiency. PMID:22323042

LIU, YING; LIU, FENG-LING; BAI, ZHI-JUN; ZHAO, NA; ZHANG, LI-YUN; LU, XIAO; CHEN, ZHENG-LIANG

2012-01-01

168

Genetic Variation and Cerebrospinal Fluid Levels of Mannose Binding Lectin in Pneumococcal Meningitis Patients  

PubMed Central

It has been suggested that genetic variants in mannose binding lectin (MBL2) influence susceptibility and outcome of invasive pneumococcal disease. We assessed the influence of genetic variation in MBL2 on susceptibility, outcome and causative serotype of pneumococcal meningitis in a prospective nationwide cohort study including 299 white patients and 216 controls. We assessed functionality of the genetic polymorphisms by measuring levels of MBL, C3a, iC3b, C5a and sC5b-9 in cerebrospinal fluid. We also performed a meta-analysis of studies on MBL2 polymorphisms and susceptibility to invasive pneumococcal disease. The risk of contracting pneumococcal meningitis was substantially increased for white individuals homozygous with the defective MBL2 0/0 genotype (odds ratio [OR] 8.21, 95% confidence interval [CI] 1.05–64.1; p?=?0.017). CSF MBL levels were significantly lower in patients with the A/0 and 0/0 genotype compared to homozygotes for the wild-type alleles (A/A; p<0.001). CSF MBL levels were positively correlated with C3a and iC3b levels, indicating complement activation by the lectin pathway. The effect of MBL2 genetic variants on susceptibility remained robust in a meta-analysis including 5 studies with 287 patients (OR 2.33, 99% CI 1.39–3.90). We conclude that MBL2 polymorphisms influence CSF MBL levels and substantially increase the risk of pneumococcal meningitis. PMID:23741476

Brouwer, Matthijs C.; Baas, Frank; van der Ende, Arie; van de Beek, Diederik

2013-01-01

169

Lysyl Hydroxylase 3 Modifies Lysine Residues to Facilitate Oligomerization of Mannan-Binding Lectin  

PubMed Central

Lysyl hydroxylase 3 (LH3) is a multifunctional protein with lysyl hydroxylase, galactosyltransferase and glucosyltransferase activities. The LH3 has been shown to modify the lysine residues both in collagens and also in some collagenous proteins. In this study we show for the first time that LH3 is essential for catalyzing formation of the glucosylgalactosylhydroxylysines of mannan-binding lectin (MBL), the first component of the lectin pathway of complement activation. Furthermore, loss of the terminal glucose units on the derivatized lysine residues in mouse embryonic fibroblasts lacking the LH3 protein leads to defective disulphide bonding and oligomerization of rat MBL-A, with a decrease in the proportion of the larger functional MBL oligomers. The oligomerization could be completely restored with the full length LH3 or the amino-terminal fragment of LH3 that possesses the glycosyltransferase activities. Our results confirm that LH3 is the only enzyme capable of glucosylating the galactosylhydroxylysine residues in proteins with a collagenous domain. In mice lacking the lysyl hydroxylase activity of LH3, but with untouched galactosyltransferase and glucosyltransferase activities, reduced circulating MBL-A levels were observed. Oligomerization was normal, however and residual lysyl hydroxylation was compensated in part by other lysyl hydroxylase isoenzymes. Our data suggest that LH3 is commonly involved in biosynthesis of collagenous proteins and the glucosylation of galactosylhydroxylysines residues by LH3 is crucial for the formation of the functional high-molecular weight MBL oligomers. PMID:25419660

Risteli, Maija; Ruotsalainen, Heli; Bergmann, Ulrich; Venkatraman Girija, Umakhanth; Wallis, Russell; Myllylä, Raili

2014-01-01

170

Could plant lectins become promising anti-tumour drugs for causing autophagic cell death?  

PubMed

Plant lectins, a group of highly diverse carbohydrate-binding proteins of non-immune origin, are ubiquitously distributed through a variety of plant species, and have recently drawn rising attention due to their remarkable ability to kill tumour cells using mechanisms implicated in autophagy. In this review, we provide a brief outline of structures of some representative plant lectins such as concanavalin A, Polygonatum cyrtonema lectin and mistletoe lectins. These can target autophagy by modulating BNIP-3, ROS-p38-p53, Ras-Raf and PI3KCI-Akt pathways, as well as Beclin-1, in many types of cancer cells. In addition, we further discuss how plant lectins are able to kill cancer cells by modulating autophagic death, for therapeutic purposes. Together, these findings provide a comprehensive perspective concerning plant lectins as promising new anti-tumour drugs, with respect to autophagic cell death in future cancer therapeutics. PMID:24033443

Liu, Z; Luo, Y; Zhou, T-T; Zhang, W-Z

2013-10-01

171

Lectin Site Interaction with Capsular Polysaccharide Mediates Nonimmune Phagocytosis of Type III Group B Streptococci  

PubMed Central

Group B Streptococcus (GBS) causes substantial morbidity but most individuals exposed to the organism remain healthy. These experiments tested the hypothesis that engagement of the complement receptor 3 (CR3) lectin site would effectively trigger neutrophil-mediated phagocytosis of complement-opsonized type III GBS by nonimmune human sera. Using an opsonophagocytosis assay, saccharides identified as interacting with the CR3 lectin site effectively inhibited neutrophil-mediated killing of type III, strain COH1. Fructose, which does not interact with the lectin site, promoted significantly less inhibition of opsonophagocytosis. Saccharide-mediated inhibition was reversed in a dose-related fashion by addition of type III, GBS capsular polysaccharide-specific immunoglobulin G. When capsule-deficient or asialo mutant type III strains were employed, the lectin site was not required. Structurally defined GBS serotypes with a side chain at least two sugars in length engaged the lectin site, and N-acetyl d-glucosamine was not a required component monosaccharide. Intact type III capsular polysaccharide interacted significantly more efficiently with the lectin site than did oligosaccharides representing approximately 5 or 20 repeating units, respectively. Taken together, these experiments indicate that interaction of type III GBS capsular polysaccharide with the lectin site of CR3 effects phagocytosis of these organisms by nonimmune serum. Use of this mechanism of innate immunity provides a potential explanation for the infrequency with which susceptible individuals exposed to type III GBS develop invasive infection. PMID:10992487

Albanyan, Esam A.; Edwards, Morven S.

2000-01-01

172

Mechanisms of complement activation by dextran-coated superparamagnetic iron oxide (SPIO) nanoworms in mouse versus human serum.  

PubMed

BackgroundThe complement system is a key component of innate immunity implicated in the neutralization and clearance of invading pathogens. Dextran coated superparamagnetic iron oxide (SPIO) nanoparticle is a promising magnetic resonance imaging (MRI) contrast agent. However, dextran SPIO has been associated with significant number of complement-related side effects in patients and some agents have been discontinued from clinical use (e.g., Feridexż). In order to improve the safety of these materials, the mechanisms of complement activation by dextran-coated SPIO and the differences between mice and humans need to be fully understood.Methods20 kDa dextran coated SPIO nanoworms (SPIO NW) were synthesized using Molday precipitation procedure. In vitro measurements of C3 deposition on SPIO NW using sera genetically deficient for various components of the classical pathway (CP), lectin pathway (LP) or alternative pathway (AP) components were used to study mechanisms of mouse complement activation. In vitro measurements of fluid phase markers of complement activation C4d and Bb and the terminal pathway marker SC5b-C9 in normal and genetically deficient sera were used to study the mechanisms of human complement activation. Mouse data were analyzed by non-paired t-test, human data were analyzed by ANOVA followed by multiple comparisons with Student-Newman-Keuls test.ResultsIn mouse sera, SPIO NW triggered the complement activation via the LP, whereas the AP contributes via the amplification loop. No involvement of the CP was observed. In human sera the LP together with the direct enhancement of the AP turnover was responsible for the complement activation. In two samples out of six healthy donors there was also a binding of anti-dextran antibodies and C1q, suggesting activation via the CP, but that did not affect the total level of C3 deposition on the particles.ConclusionsThere were important differences and similarities in the complement activation by SPIO NW in mouse versus human sera. Understanding the mechanisms of immune recognition of nanoparticles in mouse and human systems has important preclinical and clinical implications and could help design more efficient and safe nano-formulations. PMID:25425420

Banda, Nirmal K; Mehta, Gaurav; Chao, Ying; Wang, Guankui; Inturi, Swetha; Fossati-Jimack, Liliane; Botto, Marina; Wu, LinPing; Moghimi, Seyed; Simberg, Dmitri

2014-11-26

173

THE USE OF SELECTIVE PHARMACOLOGICAL INHIBITORS TO DELINEATE SIGNAL TRANSDUCTION PATHWAYS ACTIVATED DURING COMPLEMENT RECEPTOR-MEDIATED DEGRANULATION IN CHICKEN HETEROPHILS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Complement receptors (CR), along with Fc receptors, play a primary role in the removal of bacterial pathogens in poultry. The binding of serum-opsonized bacteria to CR results in the secretion of both toxic oxygen metabolites and anti-bacterial granules. We have previously shown that the stimulati...

174

Adsorption of complement factor D by polyacrylonitrile dialysis membranes  

Microsoft Academic Search

Adsorption of complement factor D by polyacrylonitrile dialysis membranes. Factor D, an essential enzyme of the alternative pathway (AP) of complement, accumulates in end-stage renal failure (ESRF). Polyacrylonitrile (PAN) membrane activates complement poorly and has been shown to adsorb C3a, the main anaphylatoxin released during complement activation. In the present work we investigated whether factor D might be adsorbed on

Manuel Pascual; Jürg A Schifferli

1993-01-01

175

The outer membrane protease PgtE of Salmonella enterica interferes with the alternative complement pathway by cleaving factors B and H.  

PubMed

The virulence factor PgtE is an outer membrane protease (omptin) of the zoonotic pathogen Salmonella enterica that causes diseases ranging from gastroenteritis to severe enteric fever. It is surface exposed in bacteria that have a short-chain, i.e., rough LPS, as observed e.g., in bacteria residing inside macrophages or just emerging from them. We investigated whether PgtE cleaves the complement factors B (B) and H (H), key proteins controlling formation and inactivation of the complement protein C3b and thereby the activity of the complement system. S. enterica serovar Typhimurium or omptin-expressing recombinant E. coli bacteria were incubated with purified human complement proteins or recombinant H fragments. PgtE cleaved both B and H, whereas its close homolog Pla of Yersinia pestis cleaved only H. H was cleaved at both N- and C-termini, while the central region resisted proteolysis. Because of multiple effects of PgtE on complement components (cleavage of C3, C3b, B, and H) we assessed its effect on the opsonophagocytosis of Salmonella. In human serum, C3 cleavage was dependent on proteolytically active PgtE. Human neutrophils interacted less with serum-opsonized FITC-stained S. enterica 14028R than with the isogenic ?pgtE strain, as analyzed by flow cytometry. In conclusion, cleavage of B and H by PgtE, together with C3 cleavage, affects the C3-mediated recognition of S. enterica by human neutrophils, thus thwarting the immune protection against Salmonella. PMID:25705210

Riva, Rauna; Korhonen, Timo K; Meri, Seppo

2015-01-01

176

Complement amplification revisited.  

PubMed

Complement amplification in blood takes place not only on activating surfaces, but in plasma as well, where it is maintained primarily by C3b2-IgG complexes. Regular products of C3 activation in serum, these complexes are inherently very efficient precursors of the alternative pathway C3 convertase. Moreover, they can bind properdin bivalently, thus creating preferred sites for convertase formation. C3b2-IgG complexes have a half-life that is substantially longer than that of free C3b, since both C3b molecules are partially protected from inactivation by factor H and I. These complexes are preferentially generated on certain naturally occurring and induced antibodies that exhibit a paratope-independent affinity for C3/C3b. Such antibodies are known to stimulate alternative complement pathway activation. We have assembled the evidence for the generation and the functional potency of the C3b2-IgG complexes, which have been studied during the last two decades. We illustrate their roles in immune complex solubilization, phagocytosis, immune response, and their ability to initiate devastating effects in ischemia/reperfusion and in aggravating inflammation. PMID:16023211

Lutz, Hans U; Jelezarova, Emiliana

2006-01-01

177

The novel complement inhibitor human CUB and Sushi multiple domains 1 (CSMD1) protein promotes factor I-mediated degradation of C4b and C3b and inhibits the membrane attack complex assembly.  

PubMed

CUB and Sushi multiple domains 1 (CSMD1) is a transmembrane protein containing 15 consecutive complement control protein (CCP) domains, which are characteristic for complement inhibitors. We expressed a membrane-bound fragment of human CSMD1 composed of the 15 C-terminal CCP domains and demonstrated that it inhibits deposition of C3b by the classical pathway on the surface of Chinese hamster ovary cells by 70% at 6% serum and of C9 (component of membrane attack complex) by 90% at 1.25% serum. Furthermore, this fragment of CSMD1 served as a cofactor to factor I-mediated degradation of C3b. In all functional assays performed, well-characterized complement inhibitors were used as positive controls, whereas Coxsackie adenovirus receptor, a protein with no effect on complement, was a negative control. Moreover, attenuation of expression in human T47 breast cancer cells that express endogenous CSMD1 significantly increased C3b deposition on these cells by 45% at 8% serum compared with that for the controls. Furthermore, by expressing a soluble 17-21 CCP fragment of CSMD1, we found that CSMD1 inhibits complement by promoting factor I-mediated C4b/C3b degradation and inhibition of MAC assembly at the level of C7. Our results revealed a novel complement inhibitor for the classical and lectin pathways. PMID:23964079

Escudero-Esparza, Astrid; Kalchishkova, Nikolina; Kurbasic, Emila; Jiang, Wen G; Blom, Anna M

2013-12-01

178

Heparan Sulfate, Including that in Bruch’s Membrane, Inhibits the Complement Alternative Pathway: Implications for Age-related Macular Degeneration  

PubMed Central

An imbalance between activation and inhibition of the complement system has been implicated in the etiologies of numerous common diseases. Allotypic variants of a key complement fluid phase regulatory protein, complement factor H (CFH), are strongly associated with age-related macular degeneration (AMD), a leading cause of worldwide visual dysfunction, although its specific role in AMD pathogenesis is still not clear. CFH was isolated from individuals carrying combinations of two of the non-synonymous coding variants most strongly associated with AMD risk, V62/H402 (risk haplotype variants), I62/Y402 (non-risk haplotype variants), and V62/Y402. These proteins were used in two functional assays (cell surface- and fluid phase-based) measuring cofactor activity of CFH in the factor I-mediated cleavage of C3b. Though no variant-specific differences in the cofactor activity were detected, when heparan sulfate (HS) was added to these assays it accelerated the rate of C3b cleavage and this effect could be modulated by degree of HS sulfation. Bruch’s membrane/choroid, a site of tissue damage in AMD, contains high concentrations of glycosaminoglycans, including HS. Addition of human Bruch’s membrane/choroid to the fluid phase assay accelerated the C3b cleavage and this effect was lost after treatment of the tissue with heparinase III. Binding of CFH variants to Bruch’s membrane/choroid isolated from elderly, non-AMD donor eyes, was similar, as was the functional activity of bound CFH. These findings refine our understanding of interactions of HS and complement and support the hypothesis that these interactions play a role in the transition between normal aging and AMD in Bruch’s membrane/choroid. PMID:20876352

Kelly, Una; Yu, Ling; Kumar, Pallavi; Ding, Jin-Dong; Jiang, Haixiang; Hageman, Gregory S.; Arshavsky, Vadim Y.; Frank, Michael M.; Hauser, Michael A.; Rickman, Catherine Bowes

2013-01-01

179

The ancient origin of the complement system  

PubMed Central

The complement system has been thought to originate exclusively in the deuterostomes. Here, we show that the central complement components already existed in the primitive protostome lineage. A functional homolog of vertebrate complement 3, CrC3, has been isolated from a ‘living fossil', the horseshoe crab (Carcinoscorpius rotundicauda). CrC3 resembles human C3 and shows closest homology to C3 sequences of lower deuterostomes. CrC3 and plasma lectins bind a wide range of microbes, forming the frontline innate immune defense system. Additionally, we identified CrC2/Bf, a homolog of vertebrate C2 and Bf that participates in C3 activation, and a C3 receptor-like sequence. Furthermore, complement-mediated phagocytosis of bacteria by the hemocytes of horseshoe crab was also observed. Thus, a primitive yet complex opsonic complement defense system is revealed in the horseshoe crab, a protostome species. Our findings demonstrate an ancient origin of the critical complement components and the opsonic defense mechanism in the Precambrian ancestor of bilateral animals. PMID:15616573

Zhu, Yong; Thangamani, Saravanan; Ho, Bow; Ding, Jeak Ling

2005-01-01

180

MASP-1 of the complement system promotes clotting via prothrombin activation.  

PubMed

Mannan-binding lectin-associated serine protease-1 (MASP-1), a protein of the complement lectin pathway, resembles thrombin in terms of structural features and substrate specificity, and it has been shown to activate coagulation factors. Here we studied the effects of MASP-1 on clot formation in whole blood (WB) and platelet-poor plasma (PPP) by thrombelastography and further elucidated the underlying mechanism. Cleavage of prothrombin by MASP-1 was investigated by SDS-PAGE and N-terminal sequencing of cleavage products. Addition of MASP-1 or thrombin to WB and PPP shortened the clotting time and clot formation time significantly compared to recalcified-only samples. The combination of MASP-1 and thrombin had additive effects. In a purified system, MASP-1 was able to induce clotting only in presence of prothrombin. Analysis of MASP-1-digested prothrombin confirmed that MASP-1 cleaves prothrombin at three cleavage sites. In conclusion, we have shown that MASP-1 is able to induce and promote clot formation measured in a global setting using the technique of thrombelastography. We further confirmed that MASP-1-induced clotting is dependent on prothrombin. Finally, we have demonstrated that MASP-1 cleaves prothrombin and identified its cleavage sites, suggesting that MASP-1 gives rise to an alternative active form of thrombin by cleaving at the cleavage site R393. PMID:25745807

Jenny, Lorenz; Dobó, József; Gál, Péter; Schroeder, Verena

2015-06-01

181

Protein engineering to target complement evasion in cancer.  

PubMed

The complement system is composed of soluble factors in plasma that enhance or "complement" immune-mediated killing through innate and adaptive mechanisms. Activation of complement causes recruitment of immune cells; opsonization of coated cells; and direct killing of affected cells through a membrane attack complex (MAC). Tumor cells up-regulate complement inhibitory factors - one of several strategies to evade the immune system. In many cases as the tumor progresses, dramatic increases in complement inhibitory factors are found on these cells. This review focuses on the classic complement pathway and the role of major complement inhibitory factors in cancer immune evasion as well as on how current protein engineering efforts are being employed to increase complement fixing or to reverse complement resistance leading to better therapeutic outcomes in oncology. Strategies discussed include engineering of antibodies to enhance complement fixation, antibodies that neutralize complement inhibitory proteins as well as engineered constructs that specifically target inhibition of the complement system. PMID:24239543

Carter, Darrick; Lieber, André

2014-01-21

182

PROTEIN ENGINEERING TO TARGET COMPLEMENT EVASION IN CANCER  

PubMed Central

The complement system is composed of soluble factors in plasma that enhance or “complement” immune-mediated killing through innate and adaptive mechanisms. Activation of complement causes recruitment of immune cells; opsonization of coated cells; and direct killing of affected cells through a membrane attack complex (MAC). Tumor cells up-regulate complement inhibitory factors -one of several strategies to evade the immune system. In many cases as the tumor progresses, dramatic increases in complement inhibitory factors are found on these cells. This review focuses on the classic complement pathway and the role of major complement inhibitory factors in cancer immune evasion as well as on how current protein engineering efforts are being employed to increase complement fixing or to reverse complement resistance leading to better therapeutic outcomes in oncology. Strategies discussed include engineering of antibodies to enhance complement fixation, antibodies that neutralize complement inhibitory proteins as well as engineered constructs that specifically target inhibition of the complement system. PMID:24239543

Carter, Darrick; Lieber, André

2013-01-01

183

Meningococcal disease and the complement system  

PubMed Central

Despite considerable advances in the understanding of the pathogenesis of meningococcal disease, this infection remains a major cause of morbidity and mortality globally. The role of the complement system in innate immune defenses against invasive meningococcal disease is well established. Individuals deficient in components of the alternative and terminal complement pathways are highly predisposed to invasive, often recurrent meningococcal infections. Genome-wide analysis studies also point to a central role for complement in disease pathogenesis. Here we review the pathophysiologic events pertinent to the complement system that accompany meningococcal sepsis in humans. Meningococci use several often redundant mechanisms to evade killing by human complement. Capsular polysaccharide and lipooligosaccharide glycan composition play critical roles in complement evasion. Some of the newly described protein vaccine antigens interact with complement components and have sparked considerable research interest. PMID:24104403

Lewis, Lisa A; Ram, Sanjay

2014-01-01

184

Role of complement in experiment silicosis  

SciTech Connect

The role of the complement system in the pathogenesis of crystal-induced pulmonary inflammation and fibrosis was evaluated using a mouse model of silicosis and congenitally complement-deficient mice. Mice lacking the fifth component of complement (B10.D2/o) were compared to C5-sufficient animals (B10.D2/n) for pulmonary changes following intratracheal instillation of silica crystals. Complement-deficient mice demonstrated a significant reduction compared to complement-sufficient mice in both cell number and protein content of lung lavage fluid throughout the 12 weeks following silica exposure. Lung hydroxyproline content (indicative of collagen deposition) was equivalent for both strains and significantly higher than controls at all times points following silica instillation. Moreover, studies in vitro have shown that silica crystals are capable of activating complement via the alternative pathway. These studies indicate that the complement system may be responsible for some of the pulmonary inflammation, but not fibrosis elicited by silica exposure.

Callis, A.H.; Sohnle, P.G.; Mandel, G.S.; Mandel, N.S.

1986-08-01

185

Fungal lectins: a growing family.  

PubMed

Fungi are members of a large group of eukaryotic organisms that include yeasts and molds, as well as the most familiar member, mushrooms. Fungal lectins with unique specificity and structures have been discovered. In general, fungal lectins are classified into specific families based on their amino acid sequences and three-dimensional structures. In this chapter, we provide an overview of the approximately 80 types of mushroom and fungal lectins that have been isolated and studied to date. In particular, we have focused on ten fungal lectins (Agaricus bisporus, Agrocybe cylindracea, Aleuria aurantia, Aspergillus oryzae, Clitocybe nebularis, Marasmius oreades, Psathyrella velutina, Rhizopus stolonifer, Pholiota squarrosa, Polyporus squamosus), many of which are commercially available and their properties, sugar-binding specificities, structural grouping into families, and applications for biological research being described. The sialic acid-specific lectins (Agrocybe cylindracea and Polyporus squamosus) and fucose-specific lectins (Aleuria aurantia, Aspergillus oryzae, Rhizopus stolonifer, and Pholiota squarrosa) each showed potential for use in identifying sialic acid glycoconjugates and fucose glycoconjugates. Although not much is currently known about fungal lectins compared to animal and plant lectins, the knowledge accumulated thus far shows great promise for several applications in the fields of taxonomy, biomedicine, and molecular and cellular biology. PMID:25117221

Kobayashi, Yuka; Kawagishi, Hirokazu

2014-01-01

186

Analysis of common bean expressed sequence tags identifies sulfur metabolic pathways active in seed and sulfur-rich proteins highly expressed in the absence of phaseolin and major lectins  

PubMed Central

Background A deficiency in phaseolin and phytohemagglutinin is associated with a near doubling of sulfur amino acid content in genetically related lines of common bean (Phaseolus vulgaris), particularly cysteine, elevated by 70%, and methionine, elevated by 10%. This mostly takes place at the expense of an abundant non-protein amino acid, S-methyl-cysteine. The deficiency in phaseolin and phytohemagglutinin is mainly compensated by increased levels of the 11S globulin legumin and residual lectins. Legumin, albumin-2, defensin and albumin-1 were previously identified as contributing to the increased sulfur amino acid content in the mutant line, on the basis of similarity to proteins from other legumes. Results Profiling of free amino acid in developing seeds of the BAT93 reference genotype revealed a biphasic accumulation of gamma-glutamyl-S-methyl-cysteine, the main soluble form of S-methyl-cysteine, with a lag phase occurring during storage protein accumulation. A collection of 30,147 expressed sequence tags (ESTs) was generated from four developmental stages, corresponding to distinct phases of gamma-glutamyl-S-methyl-cysteine accumulation, and covering the transitions to reserve accumulation and dessication. Analysis of gene ontology categories indicated the occurrence of multiple sulfur metabolic pathways, including all enzymatic activities responsible for sulfate assimilation, de novo cysteine and methionine biosynthesis. Integration of genomic and proteomic data enabled the identification and isolation of cDNAs coding for legumin, albumin-2, defensin D1 and albumin-1A and -B induced in the absence of phaseolin and phytohemagglutinin. Their deduced amino acid sequences have a higher content of cysteine than methionine, providing an explanation for the preferential increase of cysteine in the mutant line. Conclusion The EST collection provides a foundation to further investigate sulfur metabolism and the differential accumulation of sulfur amino acids in seed of common bean. Identification of sulfur-rich proteins whose levels are elevated in seed lacking phaseolin and phytohemagglutinin and sulfur metabolic genes may assist the improvement of protein quality. PMID:21615926

2011-01-01

187

Alzheimer's beta-amyloid peptides can activate the early components of complement classical pathway in a C1q-independent manner.  

PubMed

beta-Amyloid (beta-A) accumulates in the brain of patients with Alzheimer's disease (AD) and is presumably involved in the pathogenesis of this disease, on account of its neurotoxicity and complement-activating ability. Although assembly of beta-A in particular aggregates seems to be crucial, soluble non-fibrillar beta-A may also be involved. Non-fibrillar beta-A does not bind C1q, so we investigated alternative mechanisms of beta-A-dependent complement activation in vitro. On incubation with normal human plasma, non-fibrillar beta-A 1-42, and truncated peptide 1-28, induced dose-dependent activation of C1s and C4, sparing C3, as assessed by densitometric analysis of immunostained membrane after SDS-PAGE and Western blotting. The mechanism of C4 activation was not dependent on C1q, because non-fibrillar beta-A can still activate C1s and C4 in plasma genetically deficient in C1q (C1qd). In Factor XII-deficient plasma (F.XIId) the amount of cleaved C4 was about 5-10% less that in C1qd and in normal EDTA plasma; the reconstitution of F.XIId plasma with physiologic concentrations of F.XII resulted in an increased (8-15%) beta-A-dependent cleavage of C4. Thus our results indicate that the C1q-independent activation of C1 and C4 can be partially mediated by the activation products of contact system. Since the activation of contact system and of C4 leads to generation of several humoral inflammatory peptides, non-fibrillar beta-A might play a role in initiating the early inflammatory reactions leading to a multistep cascade contributing to neuronal and clinical dysfunction of AD brain. PMID:10193429

Bergamaschini, L; Canziani, S; Bottasso, B; Cugno, M; Braidotti, P; Agostoni, A

1999-03-01

188

Mannose-binding lectin (MBL) substitution: recovery of opsonic function in vivo lags behind MBL serum levels.  

PubMed

Mannose-binding lectin (MBL) deficiency is often associated with an increased risk of infection or worse prognosis in immunocompromised patients. MBL substitution in these patients might diminish these risks. We therefore performed an open, uncontrolled safety and pharmacokinetic MBL-substitution study in 12 pediatric oncology patients with chemotherapy-induced neutropenia. Twice weekly MBL infusions with plasma-derived MBL yielded MBL trough levels >1.0 microg/ml. We tested whether MBL substitution in vivo increased MBL-dependent complement activation and opsonophagocytosis of zymosan in vitro. Upon MBL substitution, opsonophagocytosis by control neutrophils increased significantly (p < 0.001) but remained suboptimal, although repeated MBL infusions resulted in improvement over time. The MBL-dependent MBL-associated serine protease (MASP)-mediated complement C3 and C4 activation also showed a suboptimal increase. To explain these results, complement activation was studied in detail. We found that in the presence of normal MASP-2 blood levels, MASP-2 activity (p < 0.0001) was reduced as well as the alternative pathway of complement activation (p < 0.05). This MBL-substitution study demonstrates that plasma-derived MBL infusions increase MBL/MASP-mediated C3 and C4 activation and opsonophagocytosis, but that higher circulating levels of plasma-derived MBL are required to achieve MBL-mediated complement activation comparable to healthy controls. Other patient cohorts should be considered to demonstrate clinical efficacy in phase II/III MBL-substitution studies, because we found a suboptimal recovery of (in vitro) biological activity upon MBL substitution in our neutropenic pediatric oncology cohort. PMID:19657091

Brouwer, Nannette; Frakking, Florine N J; van de Wetering, Marianne D; van Houdt, Michel; Hart, Margreet; Budde, Ilona Kleine; Strengers, Paul F W; Laursen, Inga; Houen, Gunnar; Roos, Dirk; Jensenius, Jens C; Caron, Huib N; Dolman, Koert M; Kuijpers, Taco W

2009-09-01

189

Infectious diseases associated with complement deficiencies.  

PubMed Central

The complement system consists of both plasma and membrane proteins. The former influence the inflammatory response, immune modulation, and host defense. The latter are complement receptors, which mediate the cellular effects of complement activation, and regulatory proteins, which protect host cells from complement-mediated injury. Complement activation occurs via either the classical or the alternative pathway, which converge at the level of C3 and share a sequence of terminal components. Four aspects of the complement cascade are critical to its function and regulation: (i) activation of the classical pathway, (ii) activation of the alternative pathway, (iii) C3 convertase formation and C3 deposition, and (iv) membrane attack complex assembly and insertion. In general, mechanisms evolved by pathogenic microbes to resist the effects of complement are targeted to these four steps. Because individual complement proteins subserve unique functional activities and are activated in a sequential manner, complement deficiency states are associated with predictable defects in complement-dependent functions. These deficiency states can be grouped by which of the above four mechanisms they disrupt. They are distinguished by unique epidemiologic, clinical, and microbiologic features and are most prevalent in patients with certain rheumatologic and infectious diseases. Ethnic background and the incidence of infection are important cofactors determining this prevalence. Although complement undoubtedly plays a role in host defense against many microbial pathogens, it appears most important in protection against encapsulated bacteria, especially Neisseria meningitidis but also Streptococcus pneumoniae, Haemophilus influenzae, and, to a lesser extent, Neisseria gonorrhoeae. The availability of effective polysaccharide vaccines and antibiotics provides an immunologic and chemotherapeutic rationale for preventing and treating infection in patients with these deficiencies. PMID:1889047

Figueroa, J E; Densen, P

1991-01-01

190

Nutritional complementation of oxidative glucose metabolism in Escherichia coli via pyrroloquinoline quinone-dependent glucose dehydrogenase and the Entner-Doudoroff pathway  

SciTech Connect

Two glucose-negative Escherichia coli mutants (ZSC113 and DF214) were unable to grow on glucose as the sole carbon source unless supplemented with pyrroloquinoline quinone (PQQ). PQQ is the cofactor for the periplasmic enzyme glucose dehydrogenase, which converts glucose to gluconate. Aerobically, E. Coli ZSC113 grew on glucose plus PQQ with a generation time of 65 min, a generation time about the same as that for wild-type E. coli in a defined glucose-salts medium. Thus, for E. coli ZSC113 the Entner-Doudoroff pathway was fully able to replace the Embden-Meyerhof-Parnas pathway. In the presence of 5% sodium dodecyl sulfate, PQQ no longer acted as a growth factor. Sodium dodecyl sulfate inhibited the formation of gluconate from glucose but not gluconate metabolism. Adaptation to PQQ-dependent growth exhibited long lag periods, except under low-phosphate conditions, in which the PhoE porin would be expressed. The authors suggest that E. coli has maintained the apoenzyme for glucose dehydrogenase and the Entner-Doudoroff pathway as adaptations to an aerobic, low-phosphate, and low-detergent aquatic environment.

Adamowicz, M.; Conway, T.; Nickerson, K.W. (Univ. of Nebraska, Lincoln (USA))

1991-07-01

191

Opsonic complement system of the solitary ascidian, Halocynthia roretzi  

Microsoft Academic Search

To elucidate the molecular architecture and function of the possibly primitive complement system of the solitary ascidian, Halochynthia roretzi, cDNA clones for the third component (C3) and mannose-binding lectin (MBL)-associated serine protease (MASP) were isolated from the hepatopancreas cDNA library. The deduced primary structure of ascidian C3 (AsC3) shows overall similarity to mammalian C3 including a typical thioester site. Two

Masaru Nonaka; Kaoru Azumi

1999-01-01

192

Mannose binding lectin (MBL) copy number polymorphism in Zebrafish (D. rerio) and identification of haplotypes resistant to L. anguillarum.  

PubMed

We describe a novel extension of the Genomic Matching Technique (GMT) that defines haplotypes of the mannose binding lectin (MBL) region in Zebrafish (D. rerio). Four ancestral haplotypes have been identified to date, with at least one of these demonstrating a significant increase in resistance to L. anguillarum. MBL activates the lectin pathway of the complement system and stimulates the development of the complement cascade and the Membrane Attack Complex. Polymorphisms in humans have been associated with increased susceptibility and severity to a number of pathogenic organisms. As teleosts have a relatively immature acquired immune system, polymorphisms within MBL and other innate defence genes are likely to be critical in defining their susceptibility/resistance to various pathogenic organisms. We report multiple copies of MBL-like genes in D. rerio, with up to three copies tightly linked within a cluster spanning approximately 15 kb on chromosome 2. Genomic analysis suggests that duplication, retroviral insertion and possibly gene mutation and/or deletion have been key factors in the evolution of this cluster. Molecular analysis has revealed extensive polymorphism, including at least five distinct amplicons and haplospecific gene copy number variation. This study demonstrates polymorphism within a critical component of the teleost innate immune system. The polymorphisms and the haplotypes encoding the unique variants are likely to be informative in defining susceptibility/resistance to infectious agents commonly encountered within aquatic environments. Future investigations will define other important haplotypes and transfer the knowledge to other finfish species, thereby enabling selection of broodstock for the aquaculture industry. PMID:17943278

Jackson, Andrew N; McLure, Craig A; Dawkins, Roger L; Keating, Peter J

2007-11-01

193

Mannan-binding lectin serum levels in 593 healthy Iranian children and adults.  

PubMed

Mannan-binding lectin (MBL) is a vital protein of innate immune system and has two critical functions: complement activation through the lectin pathway and opsonization. MBL deficiency has been classified as the most common inherited immunodeficiency known in humans (about 30% of the population), and is associated with predisposition to infections and high risk of some autoimmune diseases. The purpose of this study was to determine the profile of MBL serum level in Iranian healthy population in association with sex and age groups for the first time. We studied the serum concentration of MBL in 593 Iranian healthy cases: 340 males and 235 females in 4 different age groups by using enzyme-linked immunosorbent assay. The mean serum levels of MBL were 3.854 ± 2.77 µg/ml at the age of less than 6 months, 4.147 ± 3.54 µg/ml at 6 months to 2 years of age, 4.410 ± 3.09 µg/ml at 2-6 years and 2.207 ± 1.73 µg/ml in adults. There was significant differences in the mean concentration of MBL among different age groups of children and also between children and adults (p<0.05). No association was observed between sex and MBL concentrations. MBL serum levels of Iranian population seem to be different from some of other populations which may be explained by genetic variations. The MBL values in this study can be used as a normal reference range for future studies in Iranian population. PMID:24338257

Zahedifard, Sara; Rashidi, Elahe; Shams, Sedigheh; Saghafi, Shiva; Fazlollahi, Mohammadreza; Talebzadeh, Azadeh; Kazemnejad, Anoushirvan; Soltani, Ahmad; Pourpak, Zahra

2014-04-01

194

Chicken mannose-binding lectin (MBL) gene variants with influence on MBL serum concentrations.  

PubMed

Mannose-binding lectin (MBL) plays a major role in the innate immune defence by activating the lectin complement pathway or by acting as an opsonin. Two forms of MBL have been characterised from several species, but for humans and chickens, only one form of functional MBL has been described. The human MBL2 gene is highly polymorphic, and it causes varying MBL serum levels. Several of the single-nucleotide polymorphisms (SNPs) have been associated with the severity of diseases of bacterial, viral or parasitic origin. Association between various diseases and different MBL serum levels has also been identified in chickens. In this study, two inbred chicken lines (L10L and L10H) which have been selected for low and high MBL levels in serum and four other experimental chicken lines were analysed for polymorphism in the MBL gene. The presence of polymorphisms in the MBL gene was revealed by southern blot analyses, and the differences in the serum concentrations of MBL were found to be of transcriptional origin according to real-time quantitative reverse transcription PCR analysis. Several SNPs were discovered in the promoter and the 5' untranslated region of the chicken MBL gene which resulted in the identification of six different alleles. Mapping of regulatory elements in the promoter region was performed, and SNPs that could affect the MBL serum concentration were identified. One SNP that was found to be located in a TATA box was altered in one of the six alleles only. This allele was associated with low MBL serum concentration. PMID:23455474

Kjćrup, Rikke M; Norup, Liselotte R; Skjřdt, Karsten; Dalgaard, Tina S; Juul-Madsen, Helle R

2013-06-01

195

P-I Snake Venom Metalloproteinase Is Able to Activate the Complement System by Direct Cleavage of Central Components of the Cascade  

PubMed Central

Background Snake Venom Metalloproteinases (SVMPs) are amongst the key enzymes that contribute to the high toxicity of snake venom. We have recently shown that snake venoms from the Bothrops genus activate the Complement system (C) by promoting direct cleavage of C-components and generating anaphylatoxins, thereby contributing to the pathology and spread of the venom. The aim of the present study was to isolate and characterize the C-activating protease from Bothrops pirajai venom. Results Using two gel-filtration chromatography steps, a metalloproteinase of 23 kDa that activates Complement was isolated from Bothrops pirajai venom. The mass spectrometric identification of this protein, named here as C-SVMP, revealed peptides that matched sequences from the P-I class of SVMPs. C-SVMP activated the alternative, classical and lectin C-pathways by cleaving the ?-chain of C3, C4 and C5, thereby generating anaphylatoxins C3a, C4a and C5a. In vivo, C-SVMP induced consumption of murine complement components, most likely by activation of the pathways and/or by direct cleavage of C3, leading to a reduction of serum lytic activity. Conclusion We show here that a P-I metalloproteinase from Bothrops pirajai snake venom activated the Complement system by direct cleavage of the central C-components, i.e., C3, C4 and C5, thereby generating biologically active fragments, such as anaphylatoxins, and by cleaving the C1-Inhibitor, which may affect Complement activation control. These results suggest that direct complement activation by SVMPs may play a role in the progression of symptoms that follow envenomation. PMID:24205428

Pidde-Queiroz, Giselle; Magnoli, Fábio Carlos; Portaro, Fernanda C. V.; Serrano, Solange M. T.; Lopes, Aline Soriano; Paes Leme, Adriana Franco; van den Berg, Carmen W.; Tambourgi, Denise V.

2013-01-01

196

Complement activating cryoglobulins in the nephritis of systemic lupus erythematosus.  

PubMed Central

Complement activation in vitro by cryoglobulins isolated from the sera of 28 patients with systemic lupus erythematosus (SLE) was examined by incubating the cryoglobulin with normal human serum and performing crossed-immunoelectrophoresis of the mixture to detect C3 conversion. Eighteen of the 28 SLE cryoglobulins activated complement; eight by the classical pathway, four by the alternative pathway exclusively, and six by both pathways. In contrast only two out of 20 cryoglobulins isolated from the sera of normal subjects activated complement and both did so by the classical pathway. Twenty-three of the 28 SLE sera activated complement and complement activating cryoglobulins were isolated from 15 of these 23 sera. The parent sera of cryoglobulins activating complement had lower C4 and C3 concentrations than sera whose cryoglobulins did not split complement but these differences were not significant. The ability of SLE cryoglobulins to activate complement in vitro suggests that these immune complexes activate complement in vivo and thus may contribute to tissue damage in this disease. The activation of both classical and alternative complement pathways is in keeping with other evidence that both pathways are involved in SLE. PMID:6705265

Adu, D; Williams, D G

1984-01-01

197

A C-type lectin (LvCTL4) from Litopenaeus vannamei is a downstream molecule of the NF-?B signaling pathway and participates in antibacterial immune response.  

PubMed

C-type lectins (CTLs) play multiple roles in innate immune defense against invading pathogens in both vertebrates and invertebrates. In this study, a new C-type lectin gene from pacific white shrimp Litopenaeus vannamei (designated as LvCTL4) was cloned by rapid amplification of the cDNA ends (RACE) method. The full-length cDNA of LvCTL4 was 563 bp with open reading frame (ORF) of 471 bp encoding a polypeptide of 156 amino acids, including a putative signal sequence and a single C-type lectin-like domain (CTLD). The CTLD of 137 amino acid residues contained a mutated 'EPA' (Glu(121)-Pro(122)-Ala(123)) motif in the calcium-binding site 2 and three conserved disulfide bonds involved in structure maintenance. Tissue expression analysis showed LvCTL4 was ubiquitously distributed with high levels in gill, intestine, epithelium and hepatopancreas. The expression of LvCTL4 in gill was up-regulated in response to Vibrio parahaemolyticus challenge. RNAi knock-down of the LvCTL4 gene significantly increased mortality after V. parahaemolyticus infection. A 103 bp 5' flanking promoter sequence was obtained using the genome walking method and it contained a conserved NF-?B binding motif. Dual-Luciferase assay showed both LvDorsal and LvRelish could up regulate the promoter activity of LvCTL4. This is the first report that a shrimp C-type lectin can be regulated by both LvDorsal and LvRelish. These findings provided novel insights into the regulation of shrimp CTLs expression. PMID:25559446

Li, Haoyang; Chen, Yonggui; Li, Ming; Wang, Sheng; Zuo, Hongliang; Xu, Xiaopeng; Weng, Shaoping; He, Jianguo; Li, Chaozheng

2015-03-01

198

Localization of Complement 1 Inhibitor (C1INH/SERPING1) in Human Eyes with Age-Related Macular Degeneration  

PubMed Central

Age-related macular degeneration (AMD) is a common degenerative disease resulting in injury to the retina, retinal pigment epithelium and choriocapillaris. Recent data from histopathology, animal models and genetic studies have implicated altered regulation of the complement system as a major factor in the incidence and progression of this disease. A variant in the gene SERPING1, which encodes C1INH, an inhibitor of the classical and lectin pathways of complement activation, was recently shown to be associated with AMD. In this study we sought to determine the localization of C1INH in human donor eyes. Immunofluorescence studies using a monoclonal antibody directed against C1INH revealed localization to photoreceptor cells, inner nuclear layer neurons, choriocapillaris, and choroidal extracellular matrix. Drusen did not exhibit labeling. Genotype at rs2511989 did not appear to affect C1INH abundance or localization, nor was it associated with significant molecular weight differences when evaluated by Western blot. In a small number of eyes (n=7 AMD and n=7 control) AMD affection status was correlated with increased abundance of choroidal C1INH. These results indicate that C1INH protein is present in the retina and choroid, where it may regulate complement activation. PMID:19607829

Mullins, Robert F.; Faidley, Elizabeth A.; Daggett, Heather T.; Jomary, Catherine; Lotery, Andrew J.; Stone, Edwin M.

2009-01-01

199

Complement therapy in atypical haemolytic uraemic syndrome (aHUS)  

PubMed Central

Central to the pathogenesis of atypical haemolytic uraemic syndrome (aHUS) is over-activation of the alternative pathway of complement. Inherited defects in complement genes and autoantibodies against complement regulatory proteins have been described. The use of plasma exchange to replace non-functioning complement regulators and hyper-functional complement components in addition to the removal of CFH-autoantibodies made this the ‘gold-standard’ for management of aHUS. In the last 4 years the introduction of the complement inhibitor Eculizumab has revolutionised the management of aHUS. In this review we shall discuss the available literature on treatment strategies to date. PMID:23810412

Wong, Edwin K.S.; Goodship, Tim H.J.; Kavanagh, David

2013-01-01

200

Biomarkers of terminal complement activation confirm the diagnosis of aHUS and differentiate aHUS from TTP.  

PubMed

Atypical hemolytic uremic syndrome (aHUS) is characterized by dysregulated complement activity, the development of a thrombotic microangiopathy (TMA), and widespread end organ injury. aHUS remains a clinical diagnosis without an objective laboratory test to confirm the diagnosis. We performed a retrospective analysis of 103 patients enrolled in the Ohio State University TTP/aHUS Registry presenting with an acute TMA. Nineteen patients were clinically categorized as aHUS based on the following criteria: (1) platelet count <100 × 10(9)/L, (2) serum creatinine >2.25 mg/dL, and (3) a disintegrin and metalloprotease with thrombospondin type 1 motif, 13 (ADAMTS13) activity >10%. Sixteen of 19 patients were treated with plasma exchange (PEX) therapy, with 6/16 (38%) responding to PEX. Nine patients were treated with eculizumab with 7/9 (78%) responding to therapy. In contrast to thrombotic thrombocytopenic purpura (TTP) patients, no aHUS patients demonstrated ultralarge von Willebrand factor multimers at presentation. Median markers of generalized complement activation (C3a), alternative pathway (Bb), classical/lectin pathway (C4d), and terminal complement activation (C5a and C5b-9) were increased in the plasma of these 19 patients. Compared with a cohort of ADAMTS13-deficient TTP patients (n = 38), C5a and C5-9 were significantly higher in the 19 patients clinically characterized as aHUS, suggesting that pretreatment measurements of complement biomarkers C5a and C5b-9 may confirm the diagnosis of aHUS and differentiate it from TTP. PMID:24695849

Cataland, Spero R; Holers, V Michael; Geyer, Susan; Yang, Shangbin; Wu, Haifeng M

2014-06-12

201

Complement activation in uveitis.  

PubMed Central

To determine whether complement is activated in uveitis we have measured plasma levels of C3d, a sensitive indicator of complement activation. Increased levels of C3d were found in 11 of 15 patients with idiopathic uveitis, 13 of whom had circulating immune complexes containing complement components. Since during complement activation potent mediators of inflammation are generated, it is suggested that the activation of complement, possibly triggered by uveal deposition of immune complexes, has an important role in the pathogenesis of uveitis. PMID:3484971

Vergani, S.; Di Mauro, E.; Davies, E. T.; Spinelli, D.; Mieli-Vergani, G.; Vergani, D.

1986-01-01

202

Complement activation in progressive renal disease  

PubMed Central

Chronic kidney disease (CKD) is common and the cause of significant morbidity and mortality. The replacement of functioning nephrons by fibrosis is characteristic of progressive disease. The pathways that lead to fibrosis are not fully understood, although chronic non-resolving inflammation in the kidney is likely to drive the fibrotic response that occurs. In patients with progressive CKD there is histological evidence of inflammation in the interstitium and strategies that reduce inflammation reduce renal injury in pre-clinical models of CKD. The complement system is an integral part of the innate immune system but also augments adaptive immune responses. Complement activation is known to occur in many diverse renal diseases, including glomerulonephritis, thrombotic microangiopathies and transplant rejection. In this review we discuss current evidence that complement activation contributes to progression of CKD, how complement could cause renal inflammation and whether complement inhibition would slow progression of renal disease. PMID:25664245

Fearn, Amy; Sheerin, Neil Stephen

2015-01-01

203

Targeted Inhibition of Complement Using Complement Receptor 2-Conjugated Inhibitors Attenuates EAE  

PubMed Central

Multiple sclerosis (MS) is the most common autoimmune demyelinating disease, affecting millions of individuals worldwide. In the last two decades, many therapeutic options for the treatment of MS have become available, however they are limited in terms of effectiveness and some remain plagued by safety issues. The currently available treatment options target relapsing remitting forms of MS and are not effective against the more progressive forms of the disease. These limitations highlight a significant unmet treatment need for MS. In experimental autoimmune encephalomyelitis (EAE) studies from our laboratory, we have previously shown, using a number of complement mutant and transgenic mice, that inhibition of the alternative complement pathway and the C3 convertase confers significant protection from disease. We report here that targeted inhibition of complement activation using complement receptor 2 (CR2)-conjugated inhibitors significantly attenuates EAE. Administration of CR2-Crry (blocks all complement pathways at C3 activation) and CR2-fH (specifically blocks the alternative pathway) just prior to and during the onset of EAE blocks progression of both acute and chronic disease. These data indicate that inhibition of complement may offer an effective therapeutic approach to treating both acute and chronic forms of demyelinating disease through blocking the alternative pathway or complement convertases. PMID:23079547

Hu, Xianzhen; Tomlinson, Stephen; Barnum, Scott R.

2012-01-01

204

Molecular analysis of complement component C4 gene copy number.  

PubMed

Classical, alternative, or lectin pathways may activate the complement system cascade. The classical pathway includes the C4 protein and functions in the prevention of immune complex precipitation and in clearance of immune complexes.Two isotypes of C4-C4A and C4B-are coded by genes located at two loci within the major histocompatibility complex (MHC) on chromosome 6. While these isotypes share over 99% amino acid sequence homology, five nucleotide differences located in exon 26 are responsible for major structural and functional differences between the C4 isotypes.C4A and C4B are highly polymorphic with over 40 alleles, gene duplications, and "null alleles". C4 genes may be short (14.6 kb) or long (21 kb), due to the absence or presence of an endogenous retroviral sequence-HERV-K(C4)-in intron 9, respectively. The C4 gene copy number (GCN) can vary from 1-3 per haplotype or 2-6 per diploid genome. The variation in GCN leads to a range of C4 plasma protein concentrations among healthy subjects. In subjects with equal numbers of C4 genes, subjects with short genes have C4 plasma levels relatively higher than subjects with long genes.Variation of the C4 GCN, the gene size (long or short) and the C4 isotypes (C4A and C4B) may also lead to susceptibility to autoimmune disease. Therefore, in subjects with autoimmune disease, a low serum C4 level may be due to ongoing disease activity associated with complement activation and consumption or it may be due to genetic factors. Distinguishing between these will have clinical implications.Exact determination of GCN can be difficult, at least in part due to the high degree of homology between C4A and C4B and a variety of techniques has been described. This chapter describes a quantitative TaqMan real-time PCR (qPCR) copy number assay, based on our laboratory experience using this assay. PMID:22665233

Castley, Alison S L; Martinez, O Patricia

2012-01-01

205

von Willebrand factor is a cofactor in complement regulation.  

PubMed

Several complement proteins interact with hemostatic factors. We discovered that von Willebrand factor (VWF) acts as a cofactor for factor I-mediated cleavage of complement C3b, thereby shutting down complement activation. The complement regulatory function of VWF multimers depends on their size. Smaller VWF multimers enhance cleavage of C3b but large and ultra-large VWF (ULVWF) multimers have no effect on C3b cleavage and permit default complement activation. We conclude that normal plasma VWF multimers prevent complement activation and steer the complement pathway toward generation of inactivated C3b (iC3b). ULVWF multimers, as are present in patients with thrombotic microangiopathy, lack an inhibitory effect on complement and permit complement activation. PMID:25395424

Feng, Shuju; Liang, Xiaowen; Kroll, Michael H; Chung, Dominic W; Afshar-Kharghan, Vahid

2015-02-01

206

Opsonic Complement Component C3 in the Solitary Ascidian, Halocynthia roretzi1  

Microsoft Academic Search

The recent identification of two mannose-binding lectin-associated serine protease clones from Halocynthia roretzi, an ascidian, suggested the presence of a complement system in urochordates. To elucidate the structure and function of this possibly primitive complement system, we have isolated cDNA clones for ascidian C3 (AsC3) and purified AsC3 protein from body fluid. The deduced primary structure of AsC3 shows overall

Masaru Nonaka; Kaoru Azumi; Xin Ji; Chisato Namikawa-Yamada; Makoto Sasaki; Hidetosi Saiga; Alister W. Dodds; Hideharu Sekine; Miwako K. Homma; Misao Matsushita; Yuichi Endo; Teizo Fujita

207

Properdin in Complement Activation and Tissue Injury  

PubMed Central

The plasma protein properdin is the only known positive regulator of complement activation. Although regarded as an initiator of the alternative pathway of complement activation at the time of its discovery more than a half century ago, the role and mechanism of action of properdin in the complement cascade has undergone significant conceptual evolution since then. Despite the long history of research on properdin, however, new insight and unexpected findings on the role of properdin in complement activation, pathogen infection and host tissue injury are still being revealed by ongoing investigations. In this article, we provide a brief review on recent studies that shed new light on properdin biology, focusing on the following three topics: 1) its role as a pattern recognition molecule to direct and trigger complement activation, 2) its context-dependent requirement in complement activation on foreign and host cell surfaces, and 3) its involvement in alternative pathway complement-mediated immune disorders and considerations of properdin as a potential therapeutic target in human diseases. PMID:23816404

Lesher, AM; B, Nilsson; Song, W-C

2013-01-01

208

Lectin-probed western blot analysis.  

PubMed

Lectin-probed western blot analysis, the so-called lectin blot analysis, is a useful method to yield basic information on the glycan structures of glycoproteins, based on the carbohydrate-binding specificities of lectins. By lectin blot analysis, researchers can directly analyze the glycan structures without releasing the glycans from glycoproteins. Here, the author describes protocols for standard analysis, and applies analysis in combination with glycosidase digestion of blot. PMID:25117227

Sato, Takeshi

2014-01-01

209

Animal lectins: a historical introduction and overview  

Microsoft Academic Search

Some proteins we now regard as animal lectins were discovered before plant lectins, though many were not recognised as carbohydrate-binding proteins for many years after first being reported. As recently as 1988, most animal lectins were thought to belong to one of two primary structural families, the C-type and S-type (presently known as galectins) lectins. However, it is now clear

David C Kilpatrick

2002-01-01

210

Investigations into polymorphisms within complement receptor type 1 (CD35) thought to protect against severe malaria   

E-print Network

The human immune-regulatory protein, complement receptor type 1 (CR1, CD35), occurs on erythrocytes where it serves as the immune adherence receptor. It interacts with C3b, C4b, C1q and mannan-binding lectin (MBL). It ...

Tetteh-Quarcoo, Patience Borkor

2012-06-22

211

Original article Lectin histochemistry of dog major  

E-print Network

Original article Lectin histochemistry of dog major and minor salivary glands Mahmut Sozmen Peter, there was only weak staining in serous acini of parotid glands. Other lectins bound, to differcnt degrees gland / dog / lectin histochemistry * Correspondencc and reprints Tel.: (44)117 928 9525; fax: (44) 1 17

Boyer, Edmond

212

Complement-targeted therapeutics  

PubMed Central

The complement system is a central component of innate immunity and bridges the innate to the adaptive immune response. However, it can also turn its destructive capabilities against host cells and is involved in numerous diseases and pathological conditions. Modulation of the complement system has been recognized as a promising strategy in drug discovery, and a large number of therapeutic modalities have been developed. However, successful marketing of complement-targeted drugs has proved to be more difficult than initially expected, and many strategies have been discontinued. The US Food and Drug Administration’s approval of the first complement-specific drug, an antibody against complement component C5 (eculizumab; Soliris), in March 2007, was a long-awaited breakthrough in the field. Approval of eculizumab validates the complement system as therapeutic target and might facilitate clinical development of other promising drug candidates. PMID:17989689

Ricklin, Daniel; Lambris, John D

2010-01-01

213

The alternative pathway is required, but not alone sufficient, for retinal pathology in mouse laser-induced choroidal neovascularization  

PubMed Central

Human genetic studies have demonstrated that polymorphisms in different complement proteins can increase the risk for developing AMD. There are three pathways of complement activation, classical (CP), alternative (AP), and lectin (LP), which all activate a final common pathway. Proteins encoded by the AMD risk genes participate in the AP (CFB), CP/LP (C2), or in the AP and final common pathway (C3). Here we tested which pathway is essential in mouse laser-induced CNV. CNV was analyzed using single complement pathway knockouts (i.e., eliminating one complement pathway at a time), followed by a double knockout in which only the AP is present, and the CP and LP are disabled, using molecular, histological and electrophysiological outcomes. First, single-gene knockouts were analyzed and compared to wild type mice; C1q?/? (no CP), MBL?/? (no LP), and CFB?/? (no AP). Six days after the laser-induced lesion, mice without a functional AP had reduced CNV progression (P<0.001) and preserved ERG amplitudes, whereas those without a functional CP or LP were indistinguishable from the wild type controls (P>0.3). Second, AP-only mice (C1q?/? MBL?/?) were as protected from developing CNV as the CFB?/? mice. The degree of pathology in each strain correlated with protein levels of the angiogenic and anti-angiogenic proteins VEGF and PEDF, respectively, as well as levels of terminal pathway activation product C5a, and C9. The analysis of complement activation pathways in mouse laser-induced CNV allows for the following conclusions. Comparing the single pathway knockouts with those having only a functional AP showed: (1) that AP activation is necessary, but not alone sufficient for injury; and (2) that initial complement activation proceeds via both the LP and CP. Thus, these data indicate an important role for the AP in the generation of complement-dependent injury in the RPE and choroid via amplification of CP- and LP-initiated complement activation. Improving our understanding of the local regulation of this pathway in the eye is essential for developing improved treatment approaches for AMD. PMID:21257205

Rohrer, Bärbel; Coughlin, Beth; Kunchithapautham, Kannan; Long, Qin; Tomlinson, Stephen; Takahashi, Kazue; Holers, V. Michael

2011-01-01

214

Mannan binding lectin-associated serine protease 1 is induced by hepatitis C virus infection and activates human hepatic stellate cells  

PubMed Central

Mannan binding lectin (MBL)-associated serine protease type 1 (MASP-1) has a central role in the lectin pathway of complement activation and is required for the formation of C3 convertase. The activity of MASP-1 in the peripheral blood has been identified previously as a highly significant predictor of the severity of liver fibrosis in hepatitis C virus (HCV) infection, but not in liver disease of other aetiologies. In this study we tested the hypotheses that expression of MASP-1 may promote disease progression in HCV disease by direct activation of hepatic stellate cells (HSCs) and may additionally be up-regulated by HCV. In order to do so, we utilized a model for the maintenance of primary human HSC in the quiescent state by culture on basement membrane substrate prior to stimulation. In comparison to controls, recombinant MASP-1 stimulated quiescent human HSCs to differentiate to the activated state as assessed by both morphology and up-regulation of HSC activation markers ?-smooth muscle actin and tissue inhibitor of metalloproteinase 1. Further, the expression of MASP-1 was up-regulated significantly by HCV infection in hepatocyte cell lines. These observations suggest a new role for MASP-1 and provide a possible mechanistic link between high levels of MASP-1 and the severity of disease in HCV infection. Taken together with previous clinical observations, our new findings suggest that the balance of MASP-1 activity may be proinflammatory and act to accelerate fibrosis progression in HCV liver disease. PMID:23841802

Saeed, A; Baloch, K; Brown, R J P; Wallis, R; Chen, L; Dexter, L; McClure, C P; Shakesheff, K; Thomson, B J

2013-01-01

215

Classical complement pathway component C1q: purification of human C1q, isolation of C1q collagen-like and globular head fragments and production of recombinant C1q-derivatives. Functional characterization.  

PubMed

The classical complement pathway (CCP) activation is a multimolecular complex, composed of three subcomponents namely C1q, C1r, and C1s. C1q is the recognition subunit of this complex and its binding to the specific targets leads to the formation of active C1, which in turn activates the CCP in an immunoglobulin-dependent or -independent manner. C1q is a hexameric glycoprotein composed of 18 polypeptide chains of three different types (A, B, and C), organized in two fragments-collagen-like (CLR) and globular head (gC1q) possessing different functional activity. The contemporary knowledge of the C1q structure allows the isolation and purification of a C1q molecule from serum by combination of different chromatography procedures including ion-exchange, size-exclusion, and affinity chromatography, as well as the isolation of CLR and gC1q by limited enzymatic hydrolysis of the native C1q molecule. In this chapter, we described methods for purification of human C1q and its CLR and gC1q fragments, as well as methods for their biochemical and functional characterization. The production and purification of recombinant C1q derivatives ghA, ghB, and ghC (globular fragments of the individual C1q chains) are also presented. PMID:24218248

Kojouharova, Mihaela

2014-01-01

216

Lectin binding characteristics of mouse placental cells  

PubMed Central

The lectin binding characteristics of mouse placental cells were examined. Wax embedded tissue sections of placentae from d 14 pregnant mice were stained with 26 lectins, with a wide range of sugar specificities. Cell cultures prepared from d 14 mouse placentae and cultured for 24 h were stained with 7 of the lectins to determine if they could be used as markers for the different trophoblast cells in culture. In tissue sections all placental cell populations bound lectin but no lectin bound specifically to any single trophoblast population. All the lectins which bound to layer 1 cytotrophoblast lining the maternal blood spaces of the labyrinthine placenta also bound to the fetal endothelium of the labyrinthine placenta. Binding of lectin appeared strongest on the adluminal membrane of these cell populations suggesting a role for the carbohydrate moieties in nutrient transfer. Few lectins bound to junctional zone trophoblast. Overall, the binding of lectin to cultured cells did not correlate exactly with lectin binding to the cell populations in tissue sections. The value of lectins as markers for placental cells in culture was therefore found to be limited. Our findings indicate that carbohydrate expression by at least some placental cells may vary in culture from that expressed by the cells in vivo with obvious concerns for the validity of functional in vitro studies. PMID:10853959

STEWART, I. J.; BEBINGTON, C. R.; MUKHTAR, D. D. Y.

2000-01-01

217

Resistance of Acanthamoeba species to complement lysis.  

PubMed

Acanthamoeba species were evaluated for susceptibility to complement lysis as determined by release of radiolabeled uridine. The 3 Acanthamoeba species tested, A. culbertsoni (ATCC 30171), A. castellanii (ATCC 30010), and A. polyphaga (ATCC 30461), depleted hemolytic complement activity from normal human serum (NHS), yet were resistant to its lytic effects. Examination of microtiter plates containing amoebae incubated in NHS demonstrated formation of a pellet in the wells. Pellet formation was not observed when amoebae were incubated in human cord serum, heat-inactivated serum, or C1q-deficient serum. Ultrastructural examination of serum-treated amoebae revealed the presence of a finely granular substance that surrounded the amoebae. Treatment of amoebae with enzymes or metabolic inhibitors prior to incubation in NHS was performed to investigate the mechanism of complement resistance. Cycloheximide or cytochalasin D pretreatment increased the susceptibility of A. culbertsoni and A. castellanii to complement lysis. Cytochalasin D treatment also increased the susceptibility of A. polyphaga to complement lysis. Inhibition of serine protease activity by phenylmethylsulfonylfluoride increased complement susceptibility of all 3 species of Acanthamoeba. Enzymatic removal of surface components from A. polyphaga or A. castellanii, with trypsin, neuraminidase, or phosphatidylinositol-specific phospholipase C (PIPLC), did not affect serum resistance. In contrast, PIPLC treatment of A. culbertsoni significantly increased lysis by complement. The ability of Acanthamoeba species to activate the alternative complement pathway yet resist complement-mediated cellular lysis can be attributed to both the release of a transport-dependent extracellular matrix as well as the presence of complement inhibitory surface proteins. PMID:9576508

Toney, D M; Marciano-Cabral, F

1998-04-01

218

Plant lectins, from ancient sugar-binding proteins to emerging anti-cancer drugs in apoptosis and autophagy.  

PubMed

Ubiquitously distributed in different plant species, plant lectins are highly diverse carbohydrate-binding proteins of non-immune origin. They have interesting pharmacological activities and currently are of great interest to thousands of people working on biomedical research in cancer-related problems. It has been widely accepted that plant lectins affect both apoptosis and autophagy by modulating representative signalling pathways involved in Bcl-2 family, caspase family, p53, PI3K/Akt, ERK, BNIP3, Ras-Raf and ATG families, in cancer. Plant lectins may have a role as potential new anti-tumour agents in cancer drug discovery. Thus, here we summarize these findings on pathway- involved plant lectins, to provide a comprehensive perspective for further elucidating their potential role as novel anti-cancer drugs, with respect to both apoptosis and autophagy in cancer pathogenesis, and future therapy. PMID:25488051

Jiang, Q-L; Zhang, S; Tian, M; Zhang, S-Y; Xie, T; Chen, D-Y; Chen, Y-J; He, J; Liu, J; Ouyang, L; Jiang, X

2015-02-01

219

A novel CRIg-targeted complement inhibitor protects cells from complement damage.  

PubMed

The inappropriate activation of complement may contribute to various immune diseases. The alternative pathway (AP) predominates during complement activation regardless of the initiating pathways. Hence, the main AP regulator factor H (FH) holds great potential as an attractive therapeutic intervention. In addition, complement receptor of the immunoglobulin superfamily (CRIg) has been demonstrated to inhibit AP and, more notably, still specifically binds to C3b/iC3b. We thus developed novel CRIg-targeted complement inhibitors by connecting the functional domains of CRIg and FH, which we termed CRIg-FH and CRIg-L-FH. CRIg-L-FH, slightly more potent than CRIg-FH, considerably inhibited both AP- and also classical pathway (CP)-mediated hemolysis and successfully eliminated the deposition of C3b/iC3b. Kinetic analysis further revealed that the binding affinity constant (KD) of CRIg/FH was in the micromolar range, consistent with its long-lasting binding to complement-attacked cells. CRIg-L-FH efficiently protected aberrant erythrocytes of patients with paroxysmal nocturnal hemoglobinuria (PNH) from AP- and CP-mediated complement damage (IC50 was 22.43 and 64.69 nM, respectively). Moreover, CRIg-L-FH was found to inhibit complement activation induced by the anti-Thy1 antibody in a mesangioproliferative glomerulonephritis (MPGN) rat model. Hence, CRIg-L-FH protects glomerular mesangial cells (GMCs) from complement-mediated injury and proliferative lesions. These findings strongly suggest that CRIg/FH is a potential therapeutic drug candidate for a range of complement-mediated diseases. PMID:25114177

Qiao, Qian; Teng, Xiaoyan; Wang, Na; Lu, Renquan; Guo, Lin; Zhang, Xin; Du, Yiqun; Wang, Wenjuan; Chen, Suning; Wu, Qian; He, Guangsheng; Wang, Yingwei; Hu, Weiguo

2014-11-01

220

An overview of lectins purification strategies.  

PubMed

Lectins hold great promise not only as reagents for diagnostics and drug discovery but also as a novel class of biopharmaceutical products. In fact, new research directions in the last years have led to major developments in the uses of plant lectins as therapeutic agents against numerous diseases in an ageing society. It is even expected that lectins may occupy an important place in the biopharmaceutical industry next to monoclonal antibodies. All these new trends are placing a tremendous emphasis on the development of new approaches for faster lectins development, selection, and optimization, including alternatives methods of purification. This article reviews the isolation and purification methods used for lectins purification. Origins and applications of lectins are described, highlighting the special features of this class of proteins, such as the carbohydrated-binding domains and their importance in the development of affinity methodologies to increase and facilitate lectins purification. Published strategies for the purification of lectins from different sources are analyzed in relation to the purification methods used, their sequence, and the number of times they are used in a purification procedure. The purity of lectins is analyzed in relation to the average overall yield and purification factors obtained for each purification scheme for these proteins and the purification steps necessary. New directions are described for improving lectins separation and purification. PMID:23108612

Nascimento, Kelany S; Cunha, Ana I; Nascimento, Kyria S; Cavada, Benildo S; Azevedo, Ana M; Aires-Barros, Maria Raquel

2012-11-01

221

Interactions of Plasmodium berghei-infected erythrocytes with complement.  

PubMed

Incubation of radioactively labeled parasitized (Plasmodium berghei) erythrocytes (PE) with adherent peritoneal exudate cells in the presence of 10% (v/v) fresh mouse serum (NMS) resulted in the uptake of a proportion of radioactive material (PE). Inactivation of the added serum by heat or zymosan treatment resulted in diminished uptake of radioactivity. These results suggest that PE activated complement. Incubation of fresh NMS with PE reduced the hemolytic complement level of the serum as shown by its subsequent decreased ability to lyse antibody-coated rabbit red blood cells. No such effect was found when uninfected erythrocytes from either infected or uninfected blood were preincubated with fresh NMS. Thus, PE or PE-derived material activated complement. Addition of EGTA during incubation of fresh NMS with PE did not inhibit the decrease in complement level. This indicated that complement was activated by the alternative pathway. Complement levels decreased even when fresh NMS and PE were incubated in the presence of EDTA (which inhibits both classical and alternative pathway activation), suggesting that a complement activating factor (or a complement inhibitor) was released from the PE. However, lysis of PE after incubation with either fresh rabbit or guinea pig serum did not occur unless anti-mouse erythrocyte antibody was added. The production of a complement-activating factor by PE might explain part of the decreasing complement levels during infection and might enable the parasite to escape from a complement-mediated defense mechanism of the host. PMID:3925133

Schetters, T P; Van Lent, P; Van Zon, A A; Eling, W M

1985-05-01

222

Plasma levels of mannan-binding lectin (MBL)-associated serine proteases (MASPs) and MBL-associated protein in cardio- and cerebrovascular diseases.  

PubMed

Growing evidence suggests a prominent role of the complement system in the pathogenesis of cardio- and cerebrovascular diseases (CVD). Mannan-binding lectin-associated serine proteases (MASPs) MASP-1 and MASP-2 of the complement lectin pathway contribute to clot formation and may represent an important link between inflammation and thrombosis. MBL-associated protein MAp44 has shown cardioprotective effects in murine models. However, MAp44 has never been measured in patients with CVD and data on MASP levels in CVD are scarce. Our aim was to investigate for the first time plasma levels of MAp44 and MASP-1, -2, -3 concomitantly in patients with CVD. We performed a pilot study in 50 healthy volunteers, in stable coronary artery disease (CAD) patients with one-vessel (n?=?51) or three-vessel disease (n?=?53) and age-matched controls with normal coronary arteries (n?=?53), 49 patients after myocardial infarction (MI) and 66 patients with acute ischaemic stroke. We measured MAp44 and MASP-1 levels by in-house time-resolved immunofluorometric assays. MASP-2 and MASP-3 levels were measured using commercial enzyme-linked immunosorbent assay kits. MASP-1 levels were highest in subacute MI patients and lowest in acute stroke patients. MASP-2 levels were lower in MI and stroke patients compared with controls and CAD patients. MASP-3 and MAp44 levels did not differ between groups. MASP or MAp44 levels were not associated with severity of disease. MASP and MAp44 levels were associated with cardiovascular risk factors including dyslipidaemia, obesity and hypertension. Our results suggest that MASP levels may be altered in vascular diseases. Larger studies are needed to confirm our results and elucidate the underlying mechanisms. PMID:23607747

Frauenknecht, V; Thiel, S; Storm, L; Meier, N; Arnold, M; Schmid, J-P; Saner, H; Schroeder, V

2013-07-01

223

Mannose-Binding Lectin (MBL) and MBL-associated serine protease-2 (MASP-2) in women with malignant and benign ovarian tumours.  

PubMed

Mannose-Binding Lectin (MBL) is a serum pattern recognition molecule, able to activate complement in association with MASP proteases. Serum levels of MBL and MASP-2, activities of MBL-MASP complexes, single nucleotide polymorphisms of the MBL2 and MASP2 genes and/or their specific mRNA expression in ovarian sections were investigated in 128 patients suffering from primary ovarian cancer (OC) and compared with 197 controls (C), encompassing both patients with benign ovarian tumours (n = 123) and others with no ovarian pathology (n = 74). MBL deficiency-associated genotypes were more common among OC patients than among controls. The O/O group of genotypes was associated with ovarian cancer (OR 3.5, p = 0.02). In A/A homozygotes, MBL concentrations and activities were elevated in the OC group and correlated with C-reactive protein. Moreover, high MBL serum levels were associated with more advanced disease stage. No differences in distribution of the MASP2 +359 A>G (D120G) SNP or MASP-2 serum levels were found between cancer patients and their controls. However, the highest frequency of the A/G (MASP2) and LXA/O or O/O (MBL2) genotypes was found among OC patients with tumours of G1-2 grade (well/moderately differentiated). Furthermore, MBL deficiency-associated genotypes predicted prolonged survival. None of the parameters investigated correlated with CA125 antigen or patients' age. The local expression of MBL2 and MASP2 genes was higher in women with ovarian cancer compared with controls. It is concluded that the expression of MBL and MASP-2 is altered in ovarian cancer, possibly indicating involvement of the lectin pathway of complement activation in the disease. PMID:25038892

Swierzko, Anna St; Szala, Agnieszka; Sawicki, Sambor; Szemraj, Janusz; Sniadecki, Marcin; Sokolowska, Anna; Kaluzynski, Andrzej; Wydra, Dariusz; Cedzynski, Maciej

2014-11-01

224

Serum Mannose-Binding Lectin Concentration, but Not Genotype, Is Associated With Clostridium difficile Infection Recurrence: A Prospective Cohort Study  

PubMed Central

Background.?Mannose-binding lectin (MBL) plays a key role in the activation of the lectin-complement pathway of innate immunity, and its deficiency has been linked with several acute infections. However, its role in predisposing to, or modulating disease severity in, Clostridium difficile infection (CDI) has not been investigated. Methods.?We prospectively recruited 308 CDI case patients and 145 control patients with antibiotic-associated diarrhea (AAD). CDI outcome measures were disease severity, duration of symptoms, 30-day mortality, and 90-day recurrence. Serum concentrations of MBL were determined using a commercial enzyme-linked immunosorbent assay transferred to an electrochemiluminescence–based platform. MBL2 polymorphisms were typed using a combination of pyrosequencing and TaqMan genotyping assays. Results.?The frequency of the MBL2 genetic variants was similar to that reported in other white populations. MBL serum concentrations in CDI and AAD subjects were determined by MBL2 exonic variants B, C, and D and the haplotypes (LYPB, LYQC, and HYPD). There was no difference in either MBL concentrations or genotypes between cases and controls. MBL concentration, but not genotype, was a determinant of CDI recurrence (odds ratios, 3.18 [95% confidence interval {CI}, 1.40–7.24] and 2.61 [95% CI, 1.35–5.04] at the <50 ng/mL and <100 ng/mL cutoff points, respectively; P < .001). However, neither MBL concentration nor MBL2 genotype was linked with the other CDI outcomes. Conclusions.?Serum MBL concentration did not differentiate between CDI cases and AAD controls, but among CDI cases, MBL concentration, but not genotype, was associated with CDI recurrence, indicating that MBL acts as a modulator of disease, rather than a predisposing factor. PMID:25170052

Swale, Andrew; Miyajima, Fabio; Kolamunnage-Dona, Ruwanthi; Roberts, Paul; Little, Margaret; Beeching, Nicholas J.; Beadsworth, Mike B. J.; Liloglou, Triantafillos; Pirmohamed, Munir

2014-01-01

225

The consequence of low mannose-binding lectin plasma concentration in relation to susceptibility to Salmonella Infantis in chickens.  

PubMed

Mannose-binding lectin (MBL) is a key protein in innate immunity. MBL binds to carbohydrates on the surface of pathogens, where it initiates complement activation via the lectin-dependent pathway or facilitates opsonophagocytosis. In vitro studies have shown that human MBL is able to bind to Salmonella, but knowledge in relation to chicken MBL and Salmonella is lacking. In order to study this relation day-old chickens from two selected lines L10H and L10L, differing in MBL serum concentration, were either orally infected with S. Infantis (S.123443) or kept as non-infected controls. The differences between healthy L10H and L10L chicken sublines were more profound than differences caused by the S. Infantis infection. The average daily body weight was higher for L10H than for L10L, regardless of infection, indicating beneficial effects of MBL selection on growth. Salmonella was detected in cloacal swabs and the number of Salmonella positive chickens during the experiment was significantly higher in L10L than L10H, indicating that MBL may affect the magnitude of Salmonella colonisation in day-old chickens. MBL expression was determined in ceca tissue by real-time RT-PCR. L10H chickens showed a significantly higher relative expression than L10L at days 1 and 41 pi, regardless of infection. Finally, flow cytometric analysis of whole blood from infected chickens showed that L10H had a significantly higher count of all assessed leucocyte subsets on day 5 pi, and also a higher count of monocytes on day 12 pi than L10L. No difference was observed between infected and non-infected L10L chicken. PMID:25487759

Ulrich-Lynge, Sofie L; Dalgaard, Tina S; Norup, Liselotte R; Kjćrup, Rikke M; Olsen, John E; Sřrensen, Poul; Juul-Madsen, Helle R

2015-01-15

226

Extreme high prevalence of a defective mannose-binding lectin (MBL2) genotype in native South American West Andean populations.  

PubMed

Mannose-binding lectin (MBL) is one of the five recognition molecules in the lectin complement pathway. Common variant alleles in the promoter and structural regions of the human MBL gene (MBL2) influence the stability and serum concentration of the protein. Epidemiological studies have shown that MBL2 variant alleles are associated with susceptibility to and the course of different types of infectious and inflammatory conditions. However, it has been suggested that these alleles are maintained in different populations due to selected advantages for carriers. We investigated the MBL2 allelic variation in indigenous individuals from 12 different West Central South America localities spanning from the desert coast, high altitude Andean plates and the Amazon tropical forest within the territories of Peru (n?=?249) (Departments of Loreto, Ucayali, Lambayeque, Junin, Ayacucho, Huancayo and Puno), and Ecuador (n?=?182) (Region of Esmeraldas and Santo Domingo de los Colorados). The distribution of MBL2 genotypes among the populations showed that the defective variant LYPB haplotype was very common. It showed the highest frequencies in Puno (Taquile (0.80), Amantani (0.80) and Anapia (0.58) islander communities of the Lake Titicaca), but lower frequencies of 0.22 in Junin (Central Andean highland) and Ucayali (Central Amazonian forest), as well as 0.27 and 0.24 in the Congoma and Cayapa/Chachis populations in the Amazonian forest in Ecuador were also observed. Our results suggest that the high prevalence of the MBL2 LYPB variant causing low levels of functional MBL in serum may mainly reflect a random distribution due to a population bottleneck in the founder populations. PMID:25313559

Sandoval, José Raul; Madsen, Hans O; De Stefano, Gianfranco; Descailleaux-Dulanto, Jaime; Velazquez-Reinoso, Margarita; Ńique, Cesar; Fujita, Ricardo; Garred, Peter

2014-01-01

227

Lectin cDNA and transgenic plants derived therefrom  

DOEpatents

Transgenic plants containing cDNA encoding Gramineae lectin are described. The plants preferably contain cDNA coding for barley lectin and store the lectin in the leaves. The transgenic plants, particularly the leaves exhibit insecticidal and fungicidal properties.

Raikhel, Natasha V. (Okemos, MI)

2000-10-03

228

Complement in the Brain  

PubMed Central

The brain is considered to be an immune privileged site, because the blood-brain barrier limits entry of blood borne cells and proteins into the central nervous system (CNS). As a result, the detection and clearance of invading microorganisms and senescent cells as well as surplus neurotransmitters, aged and glycated proteins, in order to maintain a healthy environment for neuronal and glial cells, is largely confined to the innate immune system. In recent years it has become clear that many factors of innate immunity are expressed throughout the brain. Neuronal and glial cells express Toll like receptors as well as complement receptors, and virtually all complement components can be locally produced in the brain, often in response to injury or developmental cues. However, as inflammatory reactions could interfere with proper functioning of the brain, tight and fine tuned regulatory mechanisms are warranted. In age related diseases, such as Alzheimer’s disease (AD), accumulating amyloid proteins elicit complement activation and a local, chronic inflammatory response that leads to attraction and activation of glial cells that, under such activation conditions, can produce neurotoxic substances, including pro-inflammatory cytokines and oxygen radicals. This process may be exacerbated by a disturbed balance between complement activators and complement regulatory proteins such as occurs in AD, as the local synthesis of these proteins is differentially regulated by pro-inflammatory cytokines. Much knowledge about the role of complement in neurodegenerative diseases has been derived from animal studies with transgenic overexpressing or knockout mice for specific complement factors or receptors. These studies have provided insight into the potential therapeutic use of complement regulators and complement receptor antagonists in chronic neurodegenerative diseases as well as in acute conditions, such as stroke. Interestingly, recent animal studies have also indicated that complement activation products are involved in brain development and synapse formation. Not only are these findings important for the understanding of how brain development and neural network formation is organized, it may also give insights into the role of complement in processes of neurodegeneration and neuroprotection in the injured or aged and diseased adult central nervous system, and thus aid in identifying novel and specific targets for therapeutic intervention. PMID:21546088

Veerhuis, Robert; Nielsen, Henrietta M.; Tenner, Andrea J.

2011-01-01

229

Mannan-binding lectin (MBL) gene polymorphisms in ulcerative colitis and Crohn’s disease  

Microsoft Academic Search

The inflammatory bowel diseases (IBD), Crohn’s disease (CD), and ulcerative colitis (UC), are complex multifactorial traits involving both environmental and genetic factors. Mannan-binding lectin (MBL) plays an important role in non-specific immunity and complement activation. Point mutations in codons 52, 54 and 57 of exon 1 of the MBL gene are associated with decreased MBL plasma concentrations and increased susceptibility

A Rector; P Lemey; W Laffut; E Keyaerts; F Struyf; E Wollants; S Vermeire; P Rutgeerts; M Van Ranst

2001-01-01

230

Specific interaction of hepatitis C virus glycoproteins with mannan binding lectin inhibits virus entry  

Microsoft Academic Search

Mannan-binding lectin (MBL) is a soluble innate immune protein that binds to glycosylated targets. MBL acts as an opsonin\\u000a and activates complement, contributing to the destruction and clearance of infecting microorganisms. Hepatitis C virus (HCV)\\u000a encodes two envelope glycoproteins E1 and E2, expressed as non-covalent E1\\/E2 heterodimers in the viral envelope. E1 and E2\\u000a are potential ligands for MBL. Here

Kristelle S. Brown; Michael J. Keogh; Ania M. Owsianka; Richard Adair; Arvind H. Patel; James N. Arnold; Jonathan K. Ball; Robert B. Sim; Alexander W. Tarr; Timothy P. Hickling

2010-01-01

231

Mannose-binding lectin impairs Leptospira activity through the inhibitory effect on the motility of cell.  

PubMed

Mannose-binding lectin (MBL) plays key role in lectin pathway of innate immunity, and shows the ability of triggering opsonization intermediately. Substantial increase in the serum level of MBL has been confirmed during leptospirosis, which caused by a pathogenic spirochete, Leptospira. Leptospira has a fascinating locomotion pattern, which simultaneously gyrating and swimming forward, such motility enables that Leptospira is difficult to be captured by immune cells if without any assistance. In this study, the effect of mannose-binding lectin to Leptospira was quantitatively investigated by measuring some kinematic parameters, to discover the mechanism behind MBL-mediated immune responses during leptospiral infection. The results showed that mannose-binding lectin is capable of inhibiting the motility of Leptospira by transforming free swimming cells to tumbled rotating cells, resulted in the increase number of rotating cells. Otherwise, decrease in rotation rate of rotating cell has been observed. However, the swimming speed of swimming Leptospira cells showed no observable change under the effect of MBL. The inhibitory effect were only valid in a relatively short period, Leptospira cells regained their original motility after 2h. This raises an interesting topic that Leptospira is somehow able to escape from the inhibitory effect of MBL by dragging such unfavorable molecules toward to the cell end and eventually throwing it out. The inhibitory effect of MBL on the motility of Leptospira is expected to provide a new insight into lectin pathway. PMID:25644948

Xu, Jun; Guo, Yijie; Nakamura, Shuichi; Islam, Md Shafiqul; Tomioka, Rintaro; Yoneyama, Hiroshi; Isogai, Emiko

2015-02-01

232

Lectins as tools in glycoconjugate research  

Microsoft Academic Search

Lectins are ubiquitous proteins of nonimmune origin, present in plants, microorganisms, animals and humans which specifically\\u000a bind defined monosugars or oligosaccharide structures. Great progress has been made in recent years in understanding crucial\\u000a roles played by lectins in many biological processes. Elucidation of carbohydrate specificity of human and animal lectins\\u000a is of great importance for better understanding of these processes.

Albert M. Wu; Elwira Lisowska; Maria Duk; Zhangung Yang

2009-01-01

233

Plant as a plenteous reserve of lectin  

PubMed Central

Lectins are clusters of glycoproteins of nonimmune foundation that combine specifically and reversibly to carbohydrates, mainly the sugar moiety of glycoconjugates, resulting in cell agglutination and precipitation of glycoconjugates. They are universally distributed in nature, being established in plants, fungi, viruses, bacteria, crustacea, insects, and animals, but leguminacae plants are rich source of lectins. The present review reveals the structure, biological properties, and application of plant lectins. PMID:24084524

Hivrale, AU; Ingale, AG

2013-01-01

234

Kidney Diseases Caused by Complement Dysregulation: Acquired, Inherited, and Still More to Come  

PubMed Central

Inherited and acquired dysregulation of the complement alternative pathway plays an important role in multiple renal diseases. In recent years, the identification of disease-causing mutations and genetic variants in complement regulatory proteins has contributed significantly to our knowledge of the pathogenesis of complement associated glomerulopathies. In these diseases defective complement control leading to the deposition of activated complement products plays a key role. Consequently, complement-related glomerulopathies characterized by glomerular complement component 3 (C3) deposition in the absence of local immunoglobulin deposits are now collectively described by the term “C3 glomerulopathies.” Therapeutic strategies for reestablishing complement regulation by either complement blockade with the anti-C5 monoclonal antibody eculizumab or plasma substitution have been successful in several cases of C3 glomerulopathies. However, further elucidation of the underlying defects in the alternative complement pathway is awaited to develop pathogenesis-specific therapies. PMID:23227086

Heeringa, Saskia F.; Cohen, Clemens D.

2012-01-01

235

Discrimination between Host and Pathogens by the Complement System  

PubMed Central

Pathogen-specific complement activation requires direct recognition of pathogens and/or the absence of complement control mechanisms on their surfaces. Antibodies direct complement activation to potential pathogens recognized by the cellular innate and adaptive immune systems. Similarly, the plasma proteins MBL and ficolins direct activation to microorganisms expressing common carbohydrate structures. The absence of complement control proteins permits amplification of complement by the alternative pathway on any unprotected surface. The importance of complement recognition molecules (MBL, ficolins, factor H, C3, C1q, properdin, and others) to human disease are becoming clear as analysis of genetic data and knock out animals reveals links between complement proteins and specific diseases. PMID:19388159

Pangburn, Michael K.; Ferreira, Viviana P.; Cortes, Claudio

2008-01-01

236

Lectin chaperones help direct the maturation of glycoproteins in the endoplasmic reticulum  

E-print Network

Review Lectin chaperones help direct the maturation of glycoproteins in the endoplasmic reticulum Protein folding Carbohydrates Molecular chaperones Quality control Eukaryotic secretory pathway cargo fold, and interactions with a series of molecular chaperones. N-linked glycosylation provides inherent benefits to proper

Hebert, Daniel N.

237

Lectins and their application to clinical microbiology.  

PubMed Central

Lectins are generally associated with plant or animal components, selectively bind carbohydrates, and interact with procaryotic and eucaryotic cells. Lectins have various specificities that are associated with their ability to interact with acetylaminocarbohydrates, aminocarbohydrates, sialic acids, hexoses, pentoses, and as other carbohydrates. Microbial surfaces generally contain many of the sugar residues that react with lectins. Lectins are presently used in the clinical laboratory to type blood cells and are used in a wide spectrum of applications, including, in part, as carriers of chemotherapeutic agents, as mitogens, for fractionation of animal cells, and for investigations of cellular surfaces. Numerous studies have shown that lectins can be used to identify rapidly certain microorganisms isolated from a clinical specimen or directly in a clinical specimen. Lectins have been demonstrated to be important diagnostic reagents in the major realms of clinical microbiology. Thus, they have been applied in bacteriology, mycology, mycobacteriology, and virology for the identification and/or differentiation of various microorganisms. Lectins have been used successfully as epidemiologic as well as taxonomic markers of specific microorganisms. Lectins provide the clinical microbiologist with cost-effective and potential diagnostic reagents. This review describes the applications of lectins in clinical microbiology. Images PMID:2200603

Slifkin, M; Doyle, R J

1990-01-01

238

Possible mechanism for the inhibition of lectin-erythrocyte interaction in presence of endogenous lectin receptor.  

PubMed

The presence of hydrophobic sites in the lectin-I molecule was indicated by hydrophobic probes like 1-anilinonapthalene-8-sulfonic acid (ANS), 2-p-toluidinyl napthalene-6-sulfonic acid (TNS). N-phenyl-1-napthylamine (NA) and rose bengal (RB). This was further confirmed by amino acid modifications in the hydrophobic region of the lectin-I molecule. The binding of ANS, TNS, NA and RB to lectin-I was affected in the presence of NaCl. The involvement of hydrophobic interactions in rice-bean lectin-I-endogenous lectin receptor (ELR) complex were indicated by alterations in the circular dichroism and fluorescence emission spectra. The percentage of beta-conformation (55-63%) of lectin-I was decreased by addition of ELR. ELR on reacting with lectin-I reduced the fluorescence emissions of the hydrophobic probes while fluorescence emission of ANS, TNS, NA and RB were greatly enhanced in presence of lectin-I alone. N-aceyl-galactosamine did not change the fluorescence emissions of any of the hydrophobic probes in presence or in absence of lectin-I. This demonstrates that carbohydrate and hydrophobic sites may be different and non-interacting. It is proposed that the ELR in reacting with lectin-I, induced conformational changes in the lectin-I molecule and thereby affected its erythroagglutinating activity with human blood group "A" erythrocytes. PMID:9062696

Basu, P S; Datta, P K; Datta, T K

1996-12-01

239

Complement Activation and Prognosis in Patients With Type 2 Diabetes and Myocardial Infarction  

PubMed Central

OBJECTIVE The activation of the complement system may be involved in the pathology of myocardial infarction (MI) and type 2 diabetes. To explore their potential as prognostic markers, we characterized two factors in the complement cascade, the end product sC5b-9 and the mannose-binding lectin–associated Ser protease-2 (MASP-2), in type 2 diabetic patients with suspected MI. RESEARCH DESIGN AND METHODS Plasma sC5b-9 and MASP-2 were determined in patients with MI and type 2 diabetes (n = 397; median age 70; male 68%). The adjudicated end points were cardiovascular events (CVEs), including cardiovascular mortality and nonfatal MI or stroke. RESULTS The median sC5b-9 was 134 ?g/L (interquartile range [IQR] 101–190 ?g/L) and the median MASP-2 was 333 ?g/L (IQR 235–463 ?g/L), with no significant correlation between them. Women had higher sC5b-9 than men (median 152 vs. 130 ?g/L; P = 0.02). Both sC5b-9 and MASP-2 were correlated to age and creatinine clearance, while MASP-2 was also correlated to BMI. During a median follow-up of 2.4 years, CVEs occurred in 141 patients (36%). Both sC5b-9 (hazard ratio 1.37 [95% CI 1.13–1.65]; P < 0.01) and MASP-2 (0.68 [0.51–0.92]; P = 0.01) predicted CVEs in unadjusted analyses. After multiple adjustments, the predictive capacity remained for sC5b-9 (1.30 [1.02–1.66]; P = 0.04) but not for MASP-2. CONCLUSIONS In type 2 diabetic patients with MI, high levels of sC5b-9 predict future CVE. This indicates that the complement system may play a significant role in the pathology of the subsequent myocardial damage and that the pathways leading to complement activation warrant further exploration as potential therapeutic targets to improve the prognosis for these patients. PMID:22357179

Mellbin, Linda G.; Bjerre, Mette; Thiel, Steffen; Hansen, Troels K.

2012-01-01

240

The x-ray crystal structure of mannose-binding lectin-associated serine proteinase-3 reveals the structural basis for enzyme inactivity associated with the Carnevale, Mingarelli, Malpuech, and Michels (3MC) syndrome.  

PubMed

The mannose-binding lectin associated-protease-3 (MASP-3) is a member of the lectin pathway of the complement system, a key component of human innate and active immunity. Mutations in MASP-3 have recently been found to be associated with Carnevale, Mingarelli, Malpuech, and Michels (3MC) syndrome, a severe developmental disorder manifested by cleft palate, intellectual disability, and skeletal abnormalities. However, the molecular basis for MASP-3 function remains to be understood. Here we characterize the substrate specificity of MASP-3 by screening against a combinatorial peptide substrate library. Through this approach, we successfully identified a peptide substrate that was 20-fold more efficiently cleaved than any other identified to date. Furthermore, we demonstrated that mutant forms of the enzyme associated with 3MC syndrome were completely inactive against this substrate. To address the structural basis for this defect, we determined the 2.6-? structure of the zymogen form of the G666E mutant of MASP-3. These data reveal that the mutation disrupts the active site and perturbs the position of the catalytic serine residue. Together, these insights into the function of MASP-3 reveal how a mutation in this enzyme causes it to be inactive and thus contribute to the 3MC syndrome. PMID:23792966

Yongqing, Tang; Wilmann, Pascal G; Reeve, Shane B; Coetzer, Theresa H; Smith, A Ian; Whisstock, James C; Pike, Robert N; Wijeyewickrema, Lakshmi C

2013-08-01

241

Marine lectins and their medicinal applications.  

PubMed

Marine organisms have been extensively explored for the last several decades as potential sources of novel biologically active compounds, and extensive research has been conducted on lectins. Lectins derived from marine organisms are structurally diverse and also differ from those identified from terrestrial organisms. Marine lectins appear to be particularly useful in some biological applications. They seem to induce negligible immunogenicity because they have a relatively small size, are more stable due to extensive disulfide bridge formation, and have high specificity for complex glyco-conjugates and carbohydrates instead of simple sugars. It is clear that many of them have not yet been extensively studied when compared with their terrestrial counterparts. Marine lectins can be used to design and develop new potentially useful therapeutic agents. This review encompasses recent research on the isolation and identification of marine lectins with potential value in medicinal applications. PMID:25794876

Cheung, Randy Chi Fai; Wong, Jack Ho; Pan, Wenliang; Chan, Yau Sang; Yin, Cuiming; Dan, Xiuli; Ng, Tzi Bun

2015-05-01

242

Complement activation by ceramide transporter proteins.  

PubMed

C1q is the initiator of the classical complement pathway and, as such, is essential for efficient opsonization and clearance of pathogens, altered self-structures, and apoptotic cells. The ceramide transporter protein (CERT) and its longer splicing isoform CERTL are known to interact with extracellular matrix components, such as type IV collagen, and with the innate immune protein serum amyloid P. In this article, we report a novel function of CERT in the innate immune response. Both CERT isoforms, when immobilized, were found to bind the globular head region of C1q and to initiate the classical complement pathway, leading to activation of C4 and C3, as well as generation of the membrane attack complex C5b-9. In addition, C1q was shown to bind to endogenous CERTL on the surface of apoptotic cells. These results demonstrate the role of CERTs in innate immunity, especially in the clearance of apoptotic cells. PMID:24395916

Bode, Gerard H; Losen, Mario; Buurman, Wim A; Veerhuis, Robert; Molenaar, Peter C; Steinbusch, Harry W M; De Baets, Marc H; Daha, Mohamed R; Martinez-Martinez, Pilar

2014-02-01

243

Neutrophil recruitment in skin window chambers--activation by complement.  

PubMed

Complement was studied in skin window chambers, a human model of neutrophil recruitment in acute aseptic inflammation. Autologous plasma activated by the alternative pathway served as attractant; control chambers were filled with a balanced salt solution or with non-activated plasma samples. Neutrophil accumulation during a 24-hour period was consistently enhanced by activated complement in all of 15 healthy volunteers. Control chambers showed negligible cell counts. Reference assays revealed 1) consumption of the centrally placed complement component, C3, 2) generation of chemotactic activity as assessed in Boyden chambers by the standard complement activation procedure. Simultaneously obtained responses to activated complement in skin window chambers and in the Boyden assay of chemotaxis showed a highly significant, positive correlation. Our results demonstrate that the biological capacity of complement includes stimulation of neutrophil migration during simulated in vivo conditions and thus extends previous observations in animals. PMID:4036613

Elmgreen, J

1985-06-01

244

The complement system and adaptive immunity  

Microsoft Academic Search

The complement system covalently attaches C3d to microbial antigens which binds to CR2 on B lymphocytes, leading to a markedly enhanced adaptive immune response to that antigen. The enhancement is mediated by the cross-linking of the CR2–CD19 complex to mIg which augments the activation of several intracellular signalling pathways. Two additional receptors of the B lymphocyte, Fc?RIIB and CD22, have

Douglas T Fearon

1998-01-01

245

Transgenic Mice Overexpressing the Complement Inhibitor Crry as a Soluble Protein Are Protected from Antibody-induced Glomerular Injury  

Microsoft Academic Search

Summary Complement receptor 1-related gene\\/protein y (Crry) is a potent murine membrane comple- ment regulator that inhibits classical and alternative pathway C3 convertases. In nephrotoxic serum (NTS) nephritis, injected antibodies (Abs) bind to glomeruli, leading to complement ac- tivation and subsequent glomerular injury and albuminuria. To study the phenotypic effects of continuous complement pathway blockade, transgenic mice were created that

Richard J. Quigg; Chun He; Alice Lim; Dawn Berthiaume; Jessy J. Alexander; Damian Kraus; V. Michael Holers

246

Complement inhibition: a promising concept for cancer treatment  

PubMed Central

For decades, complement has been recognized as an effector arm of the immune system that contributes to the destruction of tumor cells. In fact, many therapeutic strategies have been proposed that are based on the intensification of complement-mediated responses against tumors. However, recent studies have challenged this paradigm by demonstrating a tumor-promoting role for complement. Cancer cells seem to be able to establish a convenient balance between complement activation and inhibition, taking advantage of complement initiation without suffering its deleterious effects. Complement activation may support chronic inflammation, promote an immunosuppressive microenvironment, induce angiogenesis, and activate cancer-related signaling pathways. In this context, inhibition of complement activation would be a therapeutic option for treating cancer. This concept is relatively novel and deserves closer attention. In this paper, we will summarize the mechanisms of complement activation on cancer cells, the cancer-promoting effect of complement initiation, and the rationale behind the use of complement inhibition as a therapeutic strategy against cancer. PMID:23706991

Pio, Ruben; Ajona, Daniel; Lambris, John D.

2013-01-01

247

Studies on Complement  

E-print Network

of the operation the work has been wholly unsatisfactory. Nolf next attempted to establish Eck's fistula in rabbits. Anastomosing the vena cava with the portal vein he obtained an immediate drop in complement, and he concluded from this that the liver played... as follows: I At first both antihuman and antisheep * hemolytic amboceptors from rabbits immunized against -li- the respective cells were employed. These were titrated to determine the unit of each. In the case of the antihuman hemolytic amboceptor, we...

Sherwood, Noble P.

1921-01-01

248

Complement studies in adipose patients treated with intestinal bypass.  

PubMed

Seventeen consecutive patients subjected to jejunoileostomy for obesity have been investigated for complement abnormalities and cryoglobulinaemia. The study took place 1-9 1/2 years after the operation. A concomitant clinical examination revealed recurrent arthritis in 6 (30%) of the patients. In 6 of the patients complement abnormalities were found, as activation of the classical pathway in 3 and activation of the alternative pathway in another 3 could be suspected from immunochemical data. One patient showed activation of both the classical and the alternative pathway. Two of the patients with arthritic symptoms belonged to the group showing activation of the alternative pathway. It is suggested that deficient inactivation of bacterial products from intestinal bacteria (lipopolysaccharides) have a role in the complement abnormalities found. No patient exhibited the cryoprotein complexes found earlier in this type of patients. PMID:910632

Moller, B B; Jensen, J; Nielsen, I L

1977-01-01

249

Complement activation promotes muscle inflammation during modified muscle use  

NASA Technical Reports Server (NTRS)

Modified muscle use can result in muscle inflammation that is triggered by unidentified events. In the present investigation, we tested whether the activation of the complement system is a component of muscle inflammation that results from changes in muscle loading. Modified rat hindlimb muscle loading was achieved by removing weight-bearing from the hindlimbs for 10 days followed by reloading through normal ambulation. Experimental animals were injected with the recombinant, soluble complement receptor sCR1 to inhibit complement activation. Assays for complement C4 or factor B in sera showed that sCR1 produced large reductions in the capacity for activation of the complement system through both the classical and alternative pathways. Analysis of complement C4 concentration in serum in untreated animals showed that the classical pathway was activated during the first 2 hours of reloading. Analysis of factor B concentration in untreated animals showed activation of the alternative pathway at 6 hours of reloading. Administration of sCR1 significantly attenuated the invasion of neutrophils (-49%) and ED1(+) macrophages (-52%) that occurred in nontreated animals after 6 hours of reloading. The presence of sCR1 also reduced significantly the degree of edema by 22% as compared to untreated animals. Together, these data show that increased muscle loading activated the complement system which then briefly contributes to the early recruitment of inflammatory cells during modified muscle loading.

Frenette, J.; Cai, B.; Tidball, J. G.

2000-01-01

250

Cloning and characterization of two different L-type lectin genes from the Chinese mitten crab Eriocheir sinensis.  

PubMed

L-type lectins contain a leguminous lectin domain and bind to high-mannose type oligosaccharides. In the secretory pathway, L-type lectins play crucial functions in the trafficking, sorting, and targeting of maturing glycoproteins. This study identified two novel L-type lectins, designated as EsERGIC-53 and EsVIP36, from the Chinese mitten crab Eriocheir sinensis. The complete nucleotide sequence of ERGIC-53 cDNA was 1955 bp, containing a 1506 bp open reading frame (ORF) encoding a putative protein of 501 deduced amino acids. The full-length cDNA of VIP36 was 3474 bp with a 984 bp ORF encoding a 327-amino acid peptide. The deduced ERGIC-53 and VIP36 proteins contained a putative signal peptide and an L-type lectin-like domain. Phylogenetic analysis showed that ERGIC-53 and VIP36 belonged to different clades of L-type lectin family. Reverse transcription PCR showed that ERGIC-53 and VIP36 were expressed in all tested tissues. Quantitative real-time RT-PCR analysis revealed that ERGIC-53 and VIP36 transcripts in hepatopancreas were significantly induced at various time points after infection with lipopolysaccharide (LPS), peptidoglycan (PGN), Staphylococcus aureus, Vibrio parahaemolyticus, and Aeromonas hydrophila. A bacterium-binding experiment showed that both ERGIC-53 and VIP36 could bind to different microbes. Sugar binding assay revealed that these lectins could also bind to the glycoconjugates of bacteria surface, such as LPS, PGN, d-Mannose, and N-Acetyl-d-mannosamine. Moreover, these two L-type lectins agglutinated bacteria in a calcium-dependent manner, and both exerted the ability of facilitating the clearance of injected bacteria V. parahaemolyticus in the crab. Our results suggested that ERGIC-53 and VIP36 functioned as pattern recognition receptors in the immune system of E. sinensis. PMID:24796868

Huang, Ying; Tan, Jing-Min; Wang, Zheng; Yin, Shao-Wu; Huang, Xin; Wang, Wen; Ren, Qian

2014-10-01

251

Study of complement regulatory factor H based on Forster resonance energy transfer and investigation of disease-linked genetic variants   

E-print Network

The plasma protein complement factor H (fH, 155 kDa) regulates the activity of the alternative pathway of complement activation. Factor H is monomeric, and its 20 CCP modules are arranged in a predominantly elongated ...

Pechtl, Isabell C.

2010-01-01

252

Overexpression of complement inhibitor Crry does not prevent cryoglobulin-associated membranoproliferative glomerulonephritis  

Microsoft Academic Search

Overexpression of complement inhibitor Crry does not prevent cryoglobulin-associated membranoproliferative glomerulonephritis.BackgroundMice overexpressing thymic stromal lymphopoietin (TSLP) develop mixed cryoglobulinemia with renal disease closely resembling human cryoglobulin-associated membranoproliferative glomerulonephritis (MPGN), including glomerular deposits of immunoglobulins and complement. We assessed the effect of complement inhibition through overexpression of Crry (complement receptor-1 related gene\\/protein Y), which blocks the classic and alternative pathway of

Anja S. Muhlfeld; STEPHAN SEGERER; KELLY HUDKINS; Andrew G. Farr; LIHUA BAO; DAMIAN KRAUS; V. Michael Holers; Richard J. Quigg; Charles E. Alpers

2004-01-01

253

Complement Activation and Regulation in Preeclamptic Placenta  

PubMed Central

Preeclampsia (PE) is a common disorder of pregnancy originating in the placenta. We examined whether excessive activation or poor regulation of the complement system at the maternal–fetal interface could contribute to the development of PE. Location and occurrence of complement components and regulators in placentae were analyzed. Cryostat sections of placentae were processed from 7 early-onset PE (diagnosis <34?weeks of gestation), 5 late-onset PE, 10 control pregnancies, and immunostained for 6 complement activators and 6 inhibitors. Fluorescence was quantified and compared between PE and control placentae. Gene copy numbers of complement components C4A and C4B were assessed by a quantitative PCR method. Maternal C4 deficiencies (?1 missing or non-functional C4) were most common in the early-onset PE group (71%), and more frequent in late-onset PE compared to healthy controls (60 vs. 38%). Complement C1q deposition differed significantly between control and patient groups: controls and early-onset PE patients had more C1q than late-onset PE patients (mean p?=?0.01 and p?=?0.005, respectively). C3 activation was analyzed by staining for C3b/iC3b and C3d. C3d was mostly specific to the basal syncytium and C3b/iC3b diffuse in other structures, but there were no clear differences between the study groups. Activated C4 and membrane-bound regulators CD55, CD46, and CD59 were observed abundantly in the syncytiotrophoblast. Syncytial knots, structures enriched in PE, stained specifically for the classical pathway inhibitor C4bp, whereas the key regulator alternative pathway, factor H (FH) showed a wider distribution in the placenta. Differences in C1q deposition between late- and early-onset PE groups may be indicative of the different etiology of PE symptoms in these patients. Irregular distribution of the complement regulators C4bp and FH in the PE placenta and a higher frequency of C4A deficiencies suggest a disturbed balance between complement activation and regulation in PE. PMID:25071773

Lokki, Anna Inkeri; Heikkinen-Eloranta, Jenni; Jarva, Hanna; Saisto, Terhi; Lokki, Marja-Liisa; Laivuori, Hannele; Meri, Seppo

2014-01-01

254

Roles of Serum Lectins in Host Defense  

Microsoft Academic Search

Mannan-binding protein (MBP), also called mannose-binding protein (MBP) or mannanbinding lectin (MBL), is a Ca2+-dependent (C-type) mammalian lectin specific for mannose, N-acetylglucosamine (GlcNAc), and fucose, and is an important serum component associated with innate immunity. Human MBP is\\u000a a homooligomer of an approximately 31 kDa subunit, each subunit containing a carbohydrate recognition domain (CRD) followed\\u000a by a short neck region

Nobuko Kawasaki; Bruce Yong Ma; Toshisuke Kawasaki

255

Interaction between the coagulation and complement system.  

PubMed

The complement system as a main column of innate immunity and the coagulation system as a main column in hemostasis undergo massive activation early after injury. Interactions between the two cascades have often been proposed but the precise molecular pathways of this interplay are still in the dark. To elucidate the mechanisms involved, the effects of various coagulation factors on complement activation and generation of anaphylatoxins were investigated and summarized in the light of the latest literature. Own in vitro findings suggest, that the coagulation factors FXa, FXIa and plasmin may cleave both C5 and C3, and robustly generate C5a and C3a (as detected by immunoblotting and ELISA). The produced anaphylatoxins were found to be biologically active as shown by a dose-dependent chemotactic response of neutrophils and HMC-1 cells, respectively. Thrombin did not only cleave C5 (Huber-Lang et al. 2006) but also in vitro-generated C3a when incubated with native C3. The plasmin-induced cleavage activity could be dose-dependently blocked by the serine protease inhibitor aprotinin and leupeptine. These findings suggest that various serine proteases belonging to the coagulation system are able to activate the complement cascade independently of the established pathways. Moreover, functional C5a and C3a are generated, both of which are known to be crucially involved in the inflammatory response. PMID:19025115

Amara, Umme; Rittirsch, Daniel; Flierl, Michael; Bruckner, Uwe; Klos, Andreas; Gebhard, Florian; Lambris, John D; Huber-Lang, Markus

2008-01-01

256

The Complement System in Ischemia-Reperfusion Injuries  

PubMed Central

Tissue injury and inflammation following ischemia and reperfusion of various organs has been recognized for many years. Many reviews have been written over the last several decades outlining the role of complement in ischemia/reperfusion injury. This short review provides a current state of the art knowledge on the complement pathways activated, complement components involved and a review of the clinical biologics/inhibitors used in the clinical setting of ischemia/reperfusion. This is not a complete review of the complement system in ischemia and reperfusion injury but will give the reader an updated view point of the field, potential clinical use of complement inhibitors, and the future studies needed to advance the field. PMID:22964228

Gorsuch, William B.; Chrysanthou, Elvina; Schwaeble, Wilhelm J.; Stahl, Gregory L.

2012-01-01

257

Complement and HIV-I infection/HIV-associated neurocognitive disorders.  

PubMed

The various neurological complications associated with HIV-1 infection, specifically HIV-associated neurocognitive disorders (HAND) persist as a major public health burden worldwide. Despite the widespread use of anti-retroviral therapy, the prevalence of HAND is significantly high. HAND results from the direct effects of an HIV-1 infection as well as secondary effects of HIV-1-induced immune reaction and inflammatory response. Complement, a critical mediator of innate and acquired immunity, plays important roles in defeating many viral infections by the formation of a lytic pore or indirectly by opsonization and recruitment of phagocytes. While the role of complement in the pathogenesis of HIV-1 infection and HAND has been previously recognized for over 15 years, it has been largely underestimated thus far. Complement can be activated through HIV-1 envelope proteins, mannose-binding lectins (MBL), and anti-HIV-1 antibodies. Complement not only fights against HIV-1 infection but also enhances HIV-1 infection. In addition, HIV-1 can hijack complement regulators such as CD59 and CD55 and can utilize these regulators and factor H to escape from complement attack. Normally, complement levels in brain are much lower than plasma levels and there is no or little complement deposition in brain cells. Interestingly, local production and deposition of complement are dramatically increased in HIV-1-infected brain, indicating that complement may contribute to the pathogenesis of HAND. Here, we review the current understanding of the role of complement in HIV-1 infection and HAND, as well as potential therapeutic approaches targeting the complement system for the treatment and eradications of HIV-1 infection. PMID:24639397

Liu, Fengming; Dai, Shen; Gordon, Jennifer; Qin, Xuebin

2014-04-01

258

Chicken mannose-binding lectin function in relation to antibacterial activity towards Salmonella enterica.  

PubMed

Mannose-binding lectin (MBL) is a C-type serum lectin of importance in innate immunity. Low serum concentrations of MBL have been associated with greater susceptibility to infections. In this study, binding of purified chicken MBL (cMBL) to Salmonella enterica subsp. enterica (S. enterica) serotypes B, C1 and D was investigated by flow cytometry, and Staphylococcus aureus (S. aureus) was used for comparison. For S. enterica the C1 serotypes were the only group to exhibit binding to cMBL. Furthermore, functional studies of the role of cMBL in phagocytosis and complement activation were performed. Spiking with cMBL had a dose-dependent effect on the HD11 phagocytic activity of S. enterica subsp. enterica serovar Montevideo, and a more pronounced effect in a carbohydrate competitive assay. This cMBL dose dependency of opsonophagocytic activity by HD11 cells was not observed for S. aureus. No difference in complement-dependent bactericidal activity in serum with high or low cMBL concentrations was found for S. Montevideo. On the other hand, serum with high concentrations of cMBL exhibited a greater bactericidal activity to S. aureus than serum with low concentrations of cMBL. The results presented here emphasise that chicken cMBL exhibits functional similarities with its mammalian counterparts, i.e. playing a role in opsonophagocytosis and complement activation. PMID:25623031

Ulrich-Lynge, Sofie L; Dalgaard, Tina S; Norup, Liselotte R; Song, Xiaokai; Sřrensen, Poul; Juul-Madsen, Helle R

2015-05-01

259

Atypical HUS caused by complement-related abnormalities.  

PubMed

Atypical hemolytic uremic syndrome (aHUS) is a rare disease characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. The term aHUS was historically used to distinguish this disorder from Shiga-toxin producing Escherichia coli (STEC)-HUS. Many aHUS cases (approximately 70%) are reportedly caused by uncontrolled complement activation due to genetic mutations in the alternative pathway, including complement factor H (CFH), complement factor I (CFI), membrane cofactor protein (MCP), thrombomodulin (THBD), complement component C3 (C3), and complement factor B (CFB). Mutations in the coagulation pathway, such as diacylglycerol kinase ? (DGKE) and plasminogen, are also reported to be causes of aHUS. In this review, we have focused on aHUS due to complement dysfunction. aHUS is suspected based on plasma ADAMTS13 activity of 10% or more, and being negative for STEC-HUS, in addition to the aforementioned triad. Complement genetic studies provide a more specific diagnosis of aHUS. Plasma therapy is the first-line treatment for patients with aHUS and should be initiated as soon as the diagnosis is suspected. Recently, eculizumab, a humanized monoclonal antibody against C5, was shown to be an effective treatment for aHUS. Therefore, early diagnosis and identification of the underlying pathogenic mechanism is important for improving the outcome of aHUS. PMID:25765799

Yoshida, Yoko; Matsumoto, Masanori

2015-01-01

260

[Lectins, adhesins, and lectin-like substances of lactobacilli and bifidobacteria].  

PubMed

Cell-surface adhesion factors of lactobacilli and bifidobacteria, such as lectin/adhesin proteins of S-layers, secreted lectin-like bacteriocins, and lectin-like complexes, are considered and classified in the article. Certain general and specific properties of these factors are noted, such as in vitro and in vivo adhesion, cell co(aggregation), participation in the forming of microbial biofilms and colonization of mammalian alimentary tract, as well as complexation with biopolymers and bioeffectors, specificity to glycanes and natural glycoconjugates, domain and spatial organization of adhesion factors, co-functioning with other cytokines (pro- and anti-inflammatory ones), regulation of target cell properties, and other biological and physiological activities. The authors also note possibilities of application of lectins and lectin-like proteins of probiotic strains of lactobacilli and bifidobacteria in medicine and biotechnology. PMID:16496953

Lakhtin, V M; Aleshkin, V A; Lakhtin, M V; Afanas'ev, S S; Pospelova, V V; Shenderov, B A

2006-01-01

261

The structure of C2b, a fragment of complement component C2 produced during C3 convertase formation  

PubMed Central

The second component of complement (C2) is a multi-domain serine protease that provides catalytic activity for the C3 and C5 convertases of the classical and lectin pathways of human complement. The formation of these convertases requires the Mg2+-dependent binding of C2 to C4b and the subsequent cleavage of C2 by C1s or MASP2, respectively. The crystal structure of full-length C2 is not yet available, although the structure of its C-terminal catalytic segment C2a has been determined. The crystal structure of the N-terminal segment C2b of C2 determined to 1.8?Ĺ resolution presented here reveals the arrangement of its three CCP domains. The domains are arranged differently compared with most other CCP-domain assemblies, but their arrangement is similar to that found in the Ba part of the full-length factor B structure. The crystal structures of C2a, C2b and full-length factor B are used to generate a model for C2 and a discussion of the domain association and possible interactions with C4b during formation of the C4b–C2 complex is presented. The results of this study also suggest that upon cleavage by C1s, C2a domains undergo conformational rotation while bound to C4b and the released C2b domains may remain folded together similar to as observed in the intact protein. PMID:19237749

Krishnan, Vengadesan; Xu, Yuanyuan; Macon, Kevin; Volanakis, John E.; Narayana, Sthanam V. L.

2009-01-01

262

Ion dependence of the discoidin I lectin from Dictyostelium discoideum.  

PubMed

The lectin discoidin I from Dictyostelium discoideum requires divalent cations for binding activity. The data indicate that calcium is the preferred ion in vitro. In contrast, the lectin activity of discoidin II is independent of divalent ions. PMID:6414869

Alexander, S; Cibulsky, A M; Lerner, R A

1983-01-01

263

Anesthetic management of living donor liver transplantation for complement factor H deficiency hemolytic uremic syndrome: a case report.  

PubMed

We experienced a living donor liver transplantation for a 26-month-old girl with complement factor H deficiency. Complement factor H is a plasma protein that regulates the activity of the complement pathway. Complement overactivity induced by complement factor H deficiency is associated with atypical hemolytic uremic syndrome. Liver transplantation can be the proper treatment for this condition. During the liver transplantation of these patients, prevention of the complement overactivation is necessary. Minimizing complement activation, through the use of modalities such as plasma exchange before the surgery and transfusion of fresh frozen plasma throughout the entire perioperative period, may be the key for successful liver transplantation in these patients. PMID:25006375

Park, Suk-Hee; Kim, Gaab-Soo

2014-06-01

264

Original Article Histochemical detection of the lectin-binding  

E-print Network

using periodic-acid Schiff (PAS), High Iron Diamine (HID) and Low Iron Diamine (LID). Lectin staining on the stage of oocyte maturation. zona pellucida / glycoprotein / lectin-histochemistry / wild-boar Résumé] and various domestic mammals [12­17, 25]. In those studies, lectin-staining was combined with treatments

Paris-Sud XI, Université de

265

A lectin from mycelia of the fungus Ganoderma lucidum  

Microsoft Academic Search

A lectin (GLL-M) was isolated from mycelia of Ganoderma lucidum using affinity chromatography on BSM-Toyopearl. GLL-M is a monomer in its native form with a Mr of 18 000. Another lectin was also purified from fruiting bodies of the same fungus. The two lectins were partially compared with each other.

Hirokazu Kawagishi; Shin-Ichiro Mitsunaga; Masamichi Yamawaki; Mitoko Ido; Atsushi Shimada; Tetsuya Kinoshita; Takeomi Murata; Taichi Usui; Atsuo Kimura; Seiya Chiba

1997-01-01

266

HiTrap Lectin Test Kit INSTRUCTIONS HiTrapTM Lectin Test Kit consists of four glycoprotein binding  

E-print Network

HiTrap Lectin Test Kit INSTRUCTIONS HiTrapTM Lectin Test Kit consists of four glycoprotein binding is designed to give a wide range of parameters for the separation of glycoproteins. It provides of parameters for the separation of glycoproteins. The specificity of the lectins are shown in the table below

Lebendiker, Mario

267

Luciferase fragment complementation imaging in preclinical cancer studies  

PubMed Central

The luciferase fragment complementation assay (LFCA) enables molecular events to be non-invasively imaged in live cells in vitro and in vivo in a comparatively cheap and safe manner. It is a development of previous enzyme complementation assays in which reporter genes are split into two, individually enzymatically inactive, fragments that are able to complement one another upon interaction. This complementation can be used to externally visualize cellular activities. In recent years, the number of studies which have used LFCAs to probe questions relevant to cancer have increased, and this review summarizes the most significant and interesting of these. In particular, it focuses on work conducted on the epidermal growth factor, nuclear and chemokine receptor families, and intracellular signaling pathways, including IP3, cAMP, Akt, cMyc, NRF2 and Rho GTPases. LFCAs which have been developed to image DNA methylation and detect RNA transcripts are also discussed. PMID:25594026

Lake, Madryn C.; Aboagye, Eric O.

2014-01-01

268

Complement - a key system for immune surveillance and homeostasis  

PubMed Central

Nearly a century after the significance of the human complement system was recognized we have come to realize that its versatile functions extend far beyond the elimination of microbes. Indeed, complement acts as a rapid and efficient immune surveillance system that has distinct effects on healthy and altered host cells and foreign intruders. By eliminating cellular debris and infectious microbes, orchestrating immune responses, and sending `danger' signals, complement contributes substantially to homeostasis, but it may also take action against healthy cells if not properly controlled. This review describes our updated view of the function, structure, and dynamics of the complement network, highlights its interconnection with immunity at large and with other endogenous pathways, and illustrates its dual role in homeostasis and disease. PMID:20720586

Ricklin, Daniel; Hajishengallis, George; Yang, Kun; Lambris, John D.

2010-01-01

269

Luciferase fragment complementation imaging in preclinical cancer studies.  

PubMed

The luciferase fragment complementation assay (LFCA) enables molecular events to be non-invasively imaged in live cells in vitro and in vivo in a comparatively cheap and safe manner. It is a development of previous enzyme complementation assays in which reporter genes are split into two, individually enzymatically inactive, fragments that are able to complement one another upon interaction. This complementation can be used to externally visualize cellular activities. In recent years, the number of studies which have used LFCAs to probe questions relevant to cancer have increased, and this review summarizes the most significant and interesting of these. In particular, it focuses on work conducted on the epidermal growth factor, nuclear and chemokine receptor families, and intracellular signaling pathways, including IP3, cAMP, Akt, cMyc, NRF2 and Rho GTPases. LFCAs which have been developed to image DNA methylation and detect RNA transcripts are also discussed. PMID:25594026

Lake, Madryn C; Aboagye, Eric O

2014-01-01

270

Comprehensive list of lectins: origins, natures, and carbohydrate specificities.  

PubMed

More than 100 years have passed since the first lectin ricin was discovered. Since then, a wide variety of lectins (lect means "select" in Latin) have been isolated from plants, animals, fungi, bacteria, as well as viruses, and their structures and properties have been characterized. At present, as many as 48 protein scaffolds have been identified as functional lectins from the viewpoint of three-dimensional structures as described in this chapter. In this chapter, representative 53 lectins are selected, and their major properties that include hemagglutinating activity, mitogen activity, blood group specificity, molecular weight, metal requirement, and sugar specificities are summarized as a comprehensive table. The list will provide a practically useful, comprehensive list for not only experienced lectin users but also many other non-expert researchers, who are not familiar to lectins and, therefore, have no access to advanced lectin biotechnologies described in other chapters. PMID:25117264

Kobayashi, Yuka; Tateno, Hiroaki; Ogawa, Haruko; Yamamoto, Kazuo; Hirabayashi, Jun

2014-01-01

271

Early detection of memory deficits and memory improvement with vaccinia virus complement control protein in an Alzheimer's disease model  

Microsoft Academic Search

Vaccinia virus complement control protein (VCP) inhibits both the classical and alternate complement pathways. In diseases such as traumatic brain injury (TBI) and Alzheimer's disease (AD), pathological inflammation is caused by amongst several factors, prolonged or inappropriate activation of the complement system and is a significant cause of neurodegeneration. This study investigates for the first time the use of a

Nirvana S. Pillay; Laurie A. Kellaway; Girish J. Kotwal

2008-01-01

272

COMPLEMENT FIXATION IN DISEASED TISSUES  

PubMed Central

An immunohistologic complement fixation test has been used in an effort to detect immune complexes in sections of kidney from rats injected with rabbit anti-rat kidney serum and in sections of biopsied kidneys from four humans with membranous glomerulonephritis. Sections of the rat and human kidneys were treated with fluorescein-conjugated anti-rabbit globulin or antihuman globulin respectively. Adjacent sections in each case were incubated first with fresh guinea pig serum and then in a second step were treated with fluorescein-conjugated antibodies against fixed guinea pig complement to detect sites of fixation of the complement. It was demonstrated that the sites of rabbit globulin in glomerular capillary walls of the rat kidneys and the sites of localized human globulin in thickened glomerular capillary walls and swollen glomerular endothelial cells of the human kidneys were the same sites in which guinea pig complement was fixed in vitro. It was concluded from these studies that rabbit nephrotoxic antibodies localize in rat glomeruli in complement-fixing antigen-antibody complexes. Furthermore, it was concluded that the deposits of human globulin in the glomeruli of the human kidneys behaved like antibody globulin in complement-fixing antigen-antibody complexes. The significance of demonstrating complement-fixing immune complexes in certain diseased tissues is discussed in regard to determination of the causative role of allergic reactions in disease. PMID:19867205

Burkholder, Peter M.

1961-01-01

273

Lectin-binding profile of plasmacytoid monocytes.  

PubMed

The lectin-binding profile of plasmacytoid monocytes, also known as plasmacytoid T cells, was studied in 18 axillary lymph nodes draining invasive breast carcinomas. The plasmacytoid monocytes bound fluorescein-conjugated lectins from Canavalia ensiformis (Con A), Phaseolus vulgaris (PHA-L), Arachis hypogaea (PNA), Ricinus communis (RCA I and II), and Triticum vulgaris (WGA), but no reaction was found with those from Dolichos biflorus (DBA) and Ulex europaeus (UEA I). Fluorescence was bright and the reactivity was distributed in a granular pattern in the cytoplasm of plasmacytoid monocytes, a staining pattern similar to that of monocytes and macrophages. B and T lymphocytes usually exhibited weak staining with the same lectins, and this was limited to the cell membrane. Plasmacytoid monocytes were originally thought to be closely related to the T-cell system. The results of recent immunocytologic studies and the lectin-binding profile of plasmacytoid monocytes observed in this study, however, suggest that these cells are related to the mononuclear phagocytic system. PMID:1398646

Horst, H A; Schumacher, U; Horny, H P; Lennert, K

1992-10-01

274

Identification and confirmation of differentially expressed fucosylated glycoproteins in the serum of ovarian cancer patients using a lectin array and LC-MS/MS.  

PubMed

In order to discover potential glycoprotein biomarkers in ovarian cancer, we applied a lectin array and Exactag labeling based quantitative glycoproteomics approach. A lectin array strategy was used to detect overall lectin-specific glycosylation changes in serum proteins from patients with ovarian cancer and those with benign conditions. Lectins, which showed significant differential response for fucosylation, were used to extract glycoproteins that had been labeled using isobaric chemical tags. The glycoproteins were then identified and quantified by LC-MS/MS, and five glycoproteins were found to be differentially expressed in the serum of ovarian cancer patients compared to benign diseases. The differentially expressed glycoproteins were further confirmed by lectin-ELISA and ELISA assay. Corticosteroid-binding globulin (CBG), serum amyloid p component (SAP), complement factor B (CFAB), and histidine-rich glycoprotein (HRG) were identified as potential markers for differentiating ovarian cancer from benign diseases or healthy controls. A combination of CBG and HRG (AUC = 0.825) showed comparable performance to CA125 (AUC = 0.829) in differentiating early stage ovarian cancer from healthy controls. The combination of CBG, SAP, and CA125 showed improved performance for distinguishing stage III ovarian cancer from benign diseases compared to CA125 alone. The ability of CBG, SAP, HRG, and CFAB to differentiate the serum of ovarian cancer patients from that of controls was tested using an independent set of samples. Our findings suggest that glycoprotein modifications may be a means to identify novel diagnostic markers for detection of ovarian cancer. PMID:22827608

Wu, Jing; Xie, Xiaolei; Liu, Yashu; He, Jintang; Benitez, Ricardo; Buckanovich, Ronald J; Lubman, David M

2012-09-01

275

Inhibitors of the complement system currently in development for cardiovascular disease  

Microsoft Academic Search

Controlled activation of the complement system is critical to the host-defense response of the immune system. Activated complement\\u000a is responsible for the stimulation of a localized protective inflammatory response to either invading microorganisms or foreign\\u000a molecules (toxins). However, the autologous activation of the complement system can have devastating conseuences on many organ\\u000a systems. This review discusses the various pathways involved

M. K. Pugsley; M. Abramova; T. Cole; X. Yang; W. S. Ammons

2003-01-01

276

Complement-activating ability of leucocytes from patients with complement factor I deficiency.  

PubMed Central

Previous studies from this laboratory have shown that normal peripheral blood B cells are capable of activating complement via the alternative pathway (AP), that the activation is associated with complement receptor type 2 (CR2) expression, and that erythrocytes at normal blood levels partially inhibit the activation. The purpose of the present study was to investigate whether factor I (FI) deficiency, which leads to continued formation of the AP convertase (C3bBb) resulting in the consumption of factor B and C3 and large scale generation of C3b fragments, affects the phenotype and/or function of the patients' B cells. Using flow cytometry, peripheral blood leucocytes (PBL) from two FI-deficient patients were investigated for expression of complement receptors and complement regulatory proteins, in vivo-deposited C3 fragments and in vitro complement-activating ability. CR1 levels on B cells were significantly lower in FI-deficient patients than in normal individuals, whereas CR2 levels were found to be reduced, although not to a significant extent. CR1 levels on monocytes and polymorphonuclear leucocytes (PMN) were found to be normal or slightly raised. All leucocyte subpopulations were found to be covered in vivo with C3b fragments. AP activation on B cells from FI-deficient patients in homologous serum was significantly reduced compared with that for normal individuals, whereas no in vitro activation was seen in autologous serum. In addition, the in vivo-bound C3b fragments were degraded to C3d,g when the patients' PBL were incubated in homologous serum containing EDTA. Finally, the patients, erythrocytes failed to exert any inhibition on AP activation in homologous serum. PMID:9301541

Marquart, H V; Rasmussen, J M; Leslie, R G

1997-01-01

277

Genetics Home Reference: Complement factor I deficiency  

MedlinePLUS

... literature OMIM Genetic disorder catalog Conditions > Complement factor I deficiency On this page: Description Genetic changes Inheritance ... definitions Reviewed September 2010 What is complement factor I deficiency? Complement factor I deficiency is a disorder ...

278

Complement in age-related macular degeneration: a focus on function  

PubMed Central

Age-related macular degeneration (AMD) is an inflammatory disease, which causes visual impairment and blindness in older people. The proteins of the complement system are central to the development of this disease. Local and systemic inflammation in AMD are mediated by the deregulated action of the alternative pathway of the complement system. Variants in complement system genes alter an individual's risk of developing AMD. Recent studies have shown how some risk-associated genetic variants alter the function of the complement system. In this review, we describe the evolution of the complement system and bring together recent research to form a picture of how changes in complement system genes and proteins affect the function of the complement cascade, and how this affects the development of AMD. We discuss the application of this knowledge to prevention and possible future treatments of AMD. PMID:21394116

Bradley, D T; Zipfel, P F; Hughes, A E

2011-01-01

279

Vaccinia virus complement control protein significantly improves sensorimotor function recovery after severe head trauma  

Microsoft Academic Search

Vaccinia virus complement control protein (VCP) is an immunomodulator that inhibits both the classical and alternate pathways of the complement system, therefore preventing cell death and inflammation. VCP has previously been shown to be therapeutically effective in mild and moderate traumatic brain injury models. In this study the efficacy of VCP in a severe head injury model is investigated in

Nirvana S. Pillay; Laurie A. Kellaway; Girish J. Kotwal

2007-01-01

280

Exploring the Innate Immune System: Using Complement-Medicated Cell Lysis in the Classroom  

ERIC Educational Resources Information Center

The protein complement pathway comprises an important part of the innate immunity. The use of serum to demonstrate complement-mediated destruction across a series of bacterial dilutions allows an instructor to introduce a number of important biological concepts such as bacterial growth, activation cascades, and adaptive versus innate immunity.

Fuller, Kevin G.

2008-01-01

281

The role of complement in ocular pathology  

Microsoft Academic Search

Functionally active complement system and complement regulatory proteins are present in the normal human and rodent eye. Complement\\u000a activation and its regulation by ocular complement regulatory proteins contribute to the pathology of various ocular diseases\\u000a including keratitis, uveitis and age-related macular degeneration. Furthermore, a strong relationship between age-related\\u000a macular degeneration and polymorphism in the genes of certain complement components\\/complement regulatory

Nalini S. Bora; Purushottam Jha; Puran S. Bora

2008-01-01

282

Electrophysiological correlates of Complement Coercion  

PubMed Central

This study examined the electrophysiological correlates of complement coercion. Event-related potentials (ERPs) were measured as participants read and made acceptability judgments about plausible coerced sentences, plausible non-coerced sentences, and highly implausible animacy violated sentences (“The journalist began/wrote/astonished the article before his coffee break”). Relative to non-coerced complement nouns, the coerced nouns evoked an N400 effect. This effect was not modulated by the number of possible activities implied by the coerced nouns (e.g. began reading the article; began writing the article), and did not differ in either magnitude or scalp distribution from the N400 effect evoked by the animacy violated complement nouns. We suggest that the N400 modulation to both coerced and the animacy violated complement nouns reflected different types of mismatches between the semantic restrictions of the verb and the semantic properties of the incoming complement noun. This is consistent with models holding that a verb’s semantic argument structure is represented and stored at a distinct level from its syntactic argument structure. Unlike the coerced complement noun, the animacy violated nouns also evoked a robust P600 effect, which may have been triggered by the judgments of the highly implausible (syntactically-determined) meanings of the animacy violated propositions. No additional ERP effects were seen in the coerced sentences until the sentence-final word which, relative to sentence-final words in the non-coerced sentences, evoked a sustained anteriorly-distributed positivity. We suggest that this effect reflected delayed attempts to retrieve the specific event(s) implied by coerced complement nouns. PMID:19702471

Kuperberg, Gina R.; Choi, Arim; Cohn, Neil; Paczynski, Martin; Jackendoff, Ray

2011-01-01

283

Complement in experimental Trypanosoma lewisi infection of rats.  

PubMed Central

The role of complement in host resistance to infection with Trypanosoma lewisi was studied in normal, C4-deficient, and C3-depleted rats. Complement levels were measured in normal rats throughout the course of infection. A drastic reduction of total complement and C4 hemolytic activities occurred, and C3 levels measured immunochemically were decreased. Although total complement and C4 levels were regularly reduced to less than 10% of preinfection levels regardless of parasite numbers, the degree of C3 consumption correlated with the parasitemia. C3 levels varied from 100% of preinfection in rats with light infections to 35% in animals with heavy parasitemias. Recovery to normal levels followed trypanosome elimination from the peripheral blood. The infection had no significant effect on C6 hemolytic activity. Parasitemias and C3 levels in C4-deficient rats did not differ from those of normocomplementemic controls. Depletion of C3 and late-acting components by cobra venom factor during the reproductive or adult stages of infection did not alter the parasitemias. In addition, T. lewisi and immune serum caused complement activation in vitro, which could be inhibited with ethylene glycol-bis-(beta-aminoethyl ether)N,N'-tetraacetic acid or ethylenediaminetetraacetic acid. It is concluded that T. lewisi infection in rats result in activation of the classical complement pathway with extensive consumption of the early-acting components, as well as a low degree of activation of the alternative pathway. However, complement does not appear to play a major role in the control and termination of the infection. PMID:825467

Jarvinen, J A; Dalmasso, A P

1976-01-01

284

Algal lectins as promising biomolecules for biomedical research.  

PubMed

Lectins are natural bioactive ubiquitous proteins or glycoproteins of non-immune response that bind reversibly to glycans of glycoproteins, glycolipids and polysaccharides possessing at least one non-catalytic domain causing agglutination. Some of them consist of several carbohydrate-binding domains which endow them with the properties of cell agglutination or precipitation of glycoconjugates. Lectins are rampant in nature from plants, animals and microorganisms. Among microorganisms, algae are the potent source of lectins with unique properties specifically from red algae. The demand of peculiar and neoteric biologically active substances has intensified the developments on isolation and biomedical applications of new algal lectins. Comprehensively, algal lectins are used in biomedical research for antiviral, antinociceptive, anti-inflammatory, anti-tumor activities, etc. and in pharmaceutics for the fabrication of cost-effective protein expression systems and nutraceutics. In this review, an attempt has been made to collate the information on various biomedical applications of algal lectins. PMID:23855360

Singh, Ram Sarup; Thakur, Shivani Rani; Bansal, Parveen

2015-02-01

285

Role of Complement in Immune Lysis of Trypanosoma cruzi  

PubMed Central

Studies were performed on the mechanism of immune lysis of culture forms of Trypanosoma (Schizotrypanum) cruzi. Antibody-mediated lysis is caused by complement, which is activated via the classical pathway. The properdin system is not required. The kinetics of the reaction is similar to that followed by immune lysis of sensitized sheep erythrocytes, as is the concentration of divalent cations required for optimal lysis (0.15 mm Ca2+ and 0.5 mm Mg2+), the occurrence of cell membrane uptake of the complement components C3 and C4, and the development of characteristic ultrastructural modifications on the cell membrane. Images PMID:4564786

Anziano, Dante F.; Dalmasso, Agustin P.; Lelchuk, Rosalia; Vásquez, César

1972-01-01

286

A lectin from elder (Sambucus nigra L.) bark.  

PubMed Central

A lectin was isolated from elder (Sambucus nigra) bark by affinity chromatography on fetuin-agarose. It is a tetrameric molecule (Mr 140000) composed of two different subunits of Mr 34500 and 37500 respectively, held together by intramolecular disulphide bridges. The lectin is a glycoprotein and is especially rich in asparagine/aspartic acid, glutamine/glutamic acid, valine and leucine. It is also the first lectin isolated from a species belonging to the plant family Caprifoliaceae. Images Fig. 4. PMID:6466312

Broekaert, W F; Nsimba-Lubaki, M; Peeters, B; Peumans, W J

1984-01-01

287

[Carbohydrate specificity of lectins from plants of the genus horsetail].  

PubMed

Carbohydrate specificity of partially purified lectins from 4 species of plants: horse-tail genus Equisetum (Equisetum arvense L., E. sylvaticum L., E. hyemale L. and E. tempatelia Ehrh.) has been studies. The obtained lectins have similar carbohydrate specificity. Among the tested carbohydrates the best inhibitor of activity is phenyl-2-acetamido-alpha-D-glucosaminopyranoside. Lectins poorly interact with yeasty mannan and galactomannan Trigonella foenum graecum seeds. Among glycoproteins the best inhibitor of activity is ovomucoid. PMID:12916246

Antoniuk, V O; Dubits'ky?, O L

2002-01-01

288

Lectin cDNA and transgenic plants derived therefrom  

DOEpatents

Transgenic plants containing cDNA encoding Gramineae lectin are described. The plants preferably contain cDNA coding for barley lectin and store the lectin in the leaves. The transgenic plants, particularly the leaves exhibit insecticidal and fungicidal properties. GOVERNMENT RIGHTS This application was funded under Department of Energy Contract DE-AC02-76ER01338. The U.S. Government has certain rights under this application and any patent issuing thereon. .

Raikhel, N.V.

1994-01-04

289

Lectin cDNA and transgenic plants derived therefrom  

DOEpatents

Transgenic plants containing cDNA encoding Gramineae lectin are described. The plants preferably contain cDNA coding for barley lectin and store the lectin in the leaves. The transgenic plants, particularly the leaves exhibit insecticidal and fungicidal properties. GOVERNMENT RIGHTS This application was funded under Department of Energy Contract DE-AC02-76ER01338. The U.S. Government has certain rights under this application and any patent issuing thereon.

Raikhel, Natasha V. (Okemos, MI)

1994-01-04

290

Complement activation in diseases presenting with thrombotic microangiopathy.  

PubMed

The complement system contains a great deal of biological "energy". This is demonstrated by the atypical hemolytic uremic syndrome (aHUS), which is a thrombotic microangiopathy (TMA) characterized by endothelial and blood cell damage and thrombotic vascular occlusions. Kidneys and often also other organs (brain, lungs and gastrointestinal tract) are affected. A principal pathophysiological feature in aHUS is a complement attack against endothelial cells and blood cells. This leads to platelet activation and aggregation, hemolysis, prothrombotic and inflammatory changes. The attacks can be triggered by infections, pregnancy, drugs or trauma. Complement-mediated aHUS is distinct from bacterial shiga-toxin (produced e.g. by E. coli O:157 or O:104 serotypes) induced "typical" HUS, thrombotic thrombocytopenic purpura (TTP) associated with ADAMTS13 (an adamalysin enzyme) dysfunction and from a recently described disease related to mutations in intracellular diacylglycerol kinase ? (DGKE). Mutations in proteins that regulate complement (factor H, factor I, MCP/CD46, thrombomodulin) or promote (C3, factor B) amplification of its alternative pathway or anti-factor H antibodies predispose to aHUS. The fundamental defect in aHUS is an excessive complement attack against cellular surfaces. This can be due to 1) an inability to regulate complement on self cell surfaces, 2) hyperactive C3 convertases or 3) complement activation and coagulation promoting changes on cell surfaces. The most common genetic cause is in factor H, where aHUS mutations disrupt its ability to recognize protective polyanions on surfaces where C3b has become attached. Most TMAs are thus characterized by misdirected complement activation affecting endothelial cell and platelet integrity. PMID:23743117

Meri, Seppo

2013-09-01

291

Entropy-driven lectin-recognition of multivalent glycovesicles.  

PubMed

Multivalent glycovesicle recognition over lectin layers emphasizes effects on the dynamic lateral fluidity of glycoside clusters upon multivalent binding at the bilayer surface and vice versa. PMID:24288112

Mouline, Zineb; Mahon, Eugene; Gomez, Emeline; Barragan-Montero, Veronique; Montero, Jean-Louis; Barboiu, Mihail

2014-01-21

292

Concept, strategy and realization of lectin-based glycan profiling.  

PubMed

Lectins are a diverse group of carbohydrate-binding proteins. Each lectin has its own specificity profile. It is believed that lectins exist in all living organisms that produce glycans. From a practical viewpoint, lectins have been used extensively in biochemical fields including proteomics due to their usefulness as detection and enrichment tools for specific glycans. Nevertheless, they have often been underestimated as probes, especially compared with antibodies, because of their low affinity and broad specificity. However, together with the concept of glycomics, such properties of lectins are now considered to be suitable for the task of 'profiling' in order to cover a wider range of ligands. Recently there has been rapid movement in the field of proteomics aimed at the investigation of glycan-related biomarkers. This is partly because of limitations of the present approach of simply following changes in protein-level expression, without paying sufficient attention to the fact and effects of glycosylation. The trend is reflected in the frequent use of lectins in the contexts of glycoprotein enrichment and glycan profiling. However, there are many aspects to be considered in using lectins, which differ considerably from antibodies. In this article, the author, as a developer of two unique methodologies, frontal affinity chromatography (FAC) and the lectin microarray, describes critical points concerning the use of lectins, together with the concept, strategy and means to achieve advances in these emerging glycan profiling technologies. PMID:18390573

Hirabayashi, Jun

2008-08-01

293

Are vicilins another major class of legume lectins?  

PubMed

Legume lectins comprise a structurally related, Ca/Mn-dependent, widespread, abundant and well characterized lectin family when compared to the large number of lectins from other sources described in the literature. Strangely enough, no specific function has been assigned to them aside from a possible role in storage and/or defense. Using a recent and fine-tuned methodology capable of specific lectin identification, ?-conglutin, Vicia faba vicilin and ?-lathyrin, the vicilin storage globulins from Lupinus albus, V. faba and Lathyrus sativus, respectively, were shown to be capable of affinity binding to thoroughly washed erythrocyte membranes and of specific elution with appropriate sugars. Based on this evidence and on sparse data published in the literature, a second family of legume lectins is proposed: the 7S family of storage proteins from leguminous seeds, or family II of legume lectins. These lectins are also structurally related, widespread and well characterized. In addition, they self-aggregate in a Ca/Mg, electrostatic dependent manner and are even more abundant than the family I of legume lectins. Using the same evidence, reserve and defense roles may be attributed to family II of legume lectins. PMID:25490428

Ribeiro, Ana C; Monteiro, Sara V; Carrapiço, Belmira M; Ferreira, Ricardo B

2014-01-01

294

Soluble Lectins: A New Class of Extracellular Proteins  

NASA Astrophysics Data System (ADS)

Soluble lectins of cellular slime molds and vertebrates are present at extracellular sites in the developing or adult tissues that make them. Some lectins are concentrated around cell groups, as in extracellular matrix or elastic fibers. Others are at the interface between cells and the external environment, as in much or slime. Specific glycoproteins, proteoglycans, or polysaccharides that bind these endogenous lectins may also be present at these sites. Interactions between the lectins and glycoconjugates appear to play a role in shaping extracellular environments.

Barondes, Samuel H.

1984-03-01

295

Higher complements of combinatorial sphere arrangements Higher complements of  

E-print Network

is essential if its center A H is trivial. The complement M(A) = V \\( A H) decomposes into path components)A is stable under s for all A, the arrangement is called a Coxeter arrangement. We write A = AW where W-to-one correspondence between essential Coxeter arrangements AW and finite Coxeter groups W . The latter are classified

Berger, Clemens

296

Lectin histochemistry of normal human gastric mucosa  

Microsoft Academic Search

Information about the saccharides expressed in gastric mucosa is mostly limited to the glycan content of gastric mucins and\\u000a there are only a few studies of the glycoprofiling of the constituent cells and their components. Knowledge of the glycan\\u000a expression of normal gastric mucosa is necessary for the interpretation of the significance of changes of expression in disease.\\u000a \\u000a A lectin

Chong Jiang; Sheena F. McClure; Robert W. Stoddart; John McClure

2003-01-01

297

Efficient osteoclast differentiation requires local complement activation  

PubMed Central

Previous studies using blocking antibodies suggested that bone marrow (BM)–derived C3 is required for efficient osteoclast (OC) differentiation, and that C3 receptors are involved in this process. However, the detailed underlying mechanism and the possible involvement of other complement receptors remain unclear. In this report, we found that C3?/? BM cells exhibited lower RANKL/OPG expression ratios, produced smaller amounts of macrophage colony-stimulating factor and interleukin-6 (IL-6), and generated significantly fewer OCs than wild-type (WT) BM cells. During differentiation, in addition to C3, WT BM cells locally produced all other complement components required to activate C3 and to generate C3a/C5a through the alter-native pathway, which is required for efficient OC differentiation. Abrogating C3aR/C5aR activity either genetically or pharmaceutically suppressed OC generation, while stimulating WT or C3?/? BM cells with exogenous C3a and/or C5a augmented OC differentiation. Furthermore, supplementation with IL-6 rescued OC generation from C3?/? BM cells, and neutralizing antibodies to IL-6 abolished the stimulatory effects of C3a/C5a on OC differentiation. These data indicate that during OC differentiation, BM cells locally produce components, which are activated through the alternative pathway to regulate OC differentiation. In addition to C3 receptors, C3aR/C5aR also regulate OC differentiation, at least in part, by modulating local IL-6 production. PMID:20709903

Tu, Zhidan; Bu, Hong; Dennis, James E.

2010-01-01

298

Molecular cloning of the lectin and a lectin-related protein from common Solomon's seal (Polygonatum multiflorum)  

Microsoft Academic Search

The most prominent protein ofPolygonatum multiflorum (common Solomon's seal) rhizomes has been identified as a mannose-binding lectin. Analysis of the purified lectin demonstrated that it is a tetramer of four identical subunits of 14 kDa. Molecular cloning further revealed that the lectin from this typical Liliaceae species belongs to the superfamily of monocot mannose-binding proteins. Screening of cDNA libraries constructed

Els J. M. Damme; Annick Barre; Pierre Rougé; Fred Leuven; Jan Balzarini; Willy J. Peumans

1996-01-01

299

MEMBRANE ATTACK BY COMPLEMENT: THE ASSEMBLY AND BIOLOGY OF TERMINAL COMPLEMENT COMPLEXES  

PubMed Central

Complement system activation plays an important role in both innate and acquired immunity. Activation of complement and the subsequent formation of C5b-9 channels (the membrane attack complex) on cell membranes lead to cell death. However, when the number of channels assembled on the surface of nucleated cells is limited, sublytic C5b-9 can induce cell cycle progression by activating signal transduction pathways and transcription factors and inhibiting apoptosis. This induction by C5b-9 is dependent upon the activation of the phosphatidylinositol 3-kinase/Akt/FOXO1 and ERK1 pathways in a Gi protein-dependent manner. C5b-9 induces sequential activation of CDK4 and CDK2, enabling the G1/S-phase transition and cellular proliferation. In addition, it induces RGC-32, a novel gene that plays a role in cell cycle activation by interacting with Akt and the cyclin B1-CDC2 complex. C5b-9 also inhibits apoptosis by inducing the phosphorylation of Bad and blocking the activation of FLIP, caspase-8, and Bid cleavage. Thus, sublytic C5b-9 plays an important role in cell activation, proliferation, and differentiation, thereby contributing to the maintenance of cell and tissue homeostasis. PMID:21850539

Tegla, Cosmin A.; Cudrici, Cornelia; Patel, Snehal; Trippe, Richard; Rus, Violeta; Niculescu, Florin; Rus, Horea

2013-01-01

300

L-Type lectin from the kuruma shrimp Marsupenaeus japonicus promotes hemocyte phagocytosis.  

PubMed

L-Type lectins (LTLs) contain a luminal carbohydrate recognition domain, which exhibits homology to leguminous lectins. These type I membrane proteins are involved in the early secretory pathway of animals, and have functions in glycoprotein sorting, trafficking and targeting. Recent studies suggest that LTLs may be involved in immune responses in vertebrates, but no functional studies have been reported. This study reports an LTL, designated as MjLTL1, from the kuruma shrimp Marsupenaeus japonicus. MjLTL consists of a signal peptide, leguminous lectin domain, and transmembrane region. It was upregulated following challenge of shrimp with Vibrio anguillarum. MjLTL1 could agglutinate several bacteria with the presence of calcium, and bind to several Gram-positive and Gram-negative bacteria through lipopolysaccharide and peptidoglycan binding. MjLTL1 could enhance the clearance of V. anguillarum in vivo. MjLTL1 silencing by RNA interference could impair bacterial clearance ability. Further study suggested that MjLTL1 promoted hemocyte phagocytosis. To analyze the possible mechanism, a disintegrin and metalloprotease-like protein (MjADAM) mediating the proteolytic release of extracellular domains from the membrane-bound precursors was also studied in the shrimp. MjADAM exhibited similar tissue location and expression profiles to MjLTL1. After knockdown of MjADAM, the hemocyte phagocytosis rate also declined significantly. ADAM was reported to have an ectodomain shedding function to LTL and release the ectodomain of the lectin from cell membrane. Therefore, our results suggest that the extracellular domain of MjLTL1 might be released from the cell surface as a soluble protein by MjADAM, and function as an opsonin involved in the antibacterial immune responses in shrimp. PMID:24508102

Xu, Sen; Wang, Lei; Wang, Xian-Wei; Zhao, Yan-Ran; Bi, Wen-Jie; Zhao, Xiao-Fan; Wang, Jin-Xing

2014-06-01

301

Improvisation: A Complement to Curriculum  

ERIC Educational Resources Information Center

With the growth of standardized assessment benchmarks in both the public and private paradigms, testing performance matters to institutions more than ever. In an attempt to take as many hindering variables out of this process, such as test anxiety, socioeconomic influences, and latency in cognition, Improvisation: A Complement to Curriculum seeks…

Ronald, Green A.

2006-01-01

302

Identification of Hot Spots in the Variola Virus Complement Inhibitor (SPICE) for Human Complement Regulation?  

PubMed Central

Variola virus, the causative agent of smallpox, encodes a soluble complement regulator named SPICE. Previously, SPICE has been shown to be much more potent in inactivating human complement than the vaccinia virus complement control protein (VCP), although they differ only in 11 amino acid residues. In the present study, we have expressed SPICE, VCP, and mutants of VCP by substituting each or more of the 11 non-variant VCP residues with the corresponding residue of SPICE to identify hot spots that impart functional advantage to SPICE over VCP. Our data indicate that (i) SPICE is ?90-fold more potent than VCP in inactivating human C3b, and the residues Y98, Y103, K108 and K120 are predominantly responsible for its enhanced activity; (ii) SPICE is 5.4-fold more potent in inactivating human C4b, and residues Y98, Y103, K108, K120 and L193 mainly dictate this increase; (iii) the classical pathway decay-accelerating activity of activity is only twofold higher than that of VCP, and the 11 mutations in SPICE do not significantly affect this activity; (iv) SPICE possesses significantly greater binding ability to human C3b compared to VCP, although its binding to human C4b is lower than that of VCP; (v) residue N144 is largely responsible for the increased binding of SPICE to human C3b; and (vi) the human specificity of SPICE is dictated primarily by residues Y98, Y103, K108, and K120 since these are enough to formulate VCP as potent as SPICE. Together, these results suggest that principally 4 of the 11 residues that differ between SPICE and VCP partake in its enhanced function against human complement. PMID:18216095

Yadav, Viveka Nand; Pyaram, Kalyani; Mullick, Jayati; Sahu, Arvind

2008-01-01

303

PRELP Protein Inhibits the Formation of the Complement Membrane Attack Complex*  

PubMed Central

PRELP is a 58-kDa proteoglycan found in a variety of extracellular matrices, including cartilage and at several basement membranes. In rheumatoid arthritis (RA), the cartilage tissue is destroyed and fragmented molecules, including PRELP, are released into the synovial fluid where they may interact with components of the complement system. In a previous study, PRELP was found to interact with the complement inhibitor C4b-binding protein, which was suggested to locally down-regulate complement activation in joints during RA. Here we show that PRELP directly inhibits all pathways of complement by binding C9 and thereby prevents the formation of the membrane attack complex (MAC). PRELP does not interfere with the interaction between C9 and already formed C5b-8, but inhibits C9 polymerization thereby preventing formation of the lytic pore. The alternative pathway is moreover inhibited already at the level of C3-convertase formation due to an interaction between PRELP and C3. This suggests that PRELP may down-regulate complement attack at basement membranes and on damaged cartilage and therefore limit pathological complement activation in inflammatory disease such as RA. The net outcome of PRELP-mediated complement inhibition will highly depend on the local concentration of other complement modulating molecules as well as on the local concentration of available complement proteins. PMID:22267731

Happonen, Kaisa E.; Fürst, Camilla Melin; Saxne, Tore; Heinegĺrd, Dick; Blom, Anna M.

2012-01-01

304

Downregulation of Hsp70 inhibits apoptosis induced by sialic acid-binding lectin (leczyme).  

PubMed

Heat shock proteins (Hsps) are molecular chaperones that maintain homeostasis of organisms. In regards to the Hsps, many studies have investigated the structure, expression, localization and functions of Hsp70 and Hsc70 including expression in the glycosphingolipid-enriched microdomain (GEM) on the cell surface and involvement in cell death. Sialic acid-binding lectin (SBL) isolated from oocytes of Rana catesbeiana is a multifunctional protein which has lectin activity, ribonuclease activity and antitumor activity. SBL has potential as a new type of anticancer drug, since it causes cancer-selective induction of apoptosis by multiple signaling pathways in which RNA is its target; and the participation of the mitochondrial pathway and the endoplasmic reticulum (ER) stress-mediated pathway has been suggested. It has also been suggested that receptor(s) for SBL (SBLR) may exist in the GEM on the cell surface. In the present study, we studied the possible involvement of Hsp70 and Hsc70 in SBL-induced apoptosis. We showed that Hsp70 and Hsc70 were expressed on the P388 cell surface similar to SBLR, and their distribution in cells dramatically changed immediately prior to the execution of apoptosis following stimulation of SBL. Functional study of Hsp70 revealed that decreased expression of Hsp70 diminished the apoptosis induced by SBL. It is suggested that Hsp70 participates in the antitumor effect of SBL. PMID:24173532

Tatsuta, Takeo; Hosono, Masahiro; Ogawa, Yukiko; Inage, Kyoko; Sugawara, Shigeki; Nitta, Kazuo

2014-01-01

305

Downregulation of Hsp70 inhibits apoptosis induced by sialic acid-binding lectin (leczyme)  

PubMed Central

Heat shock proteins (Hsps) are molecular chaperones that maintain homeostasis of organisms. In regards to the Hsps, many studies have investigated the structure, expression, localization and functions of Hsp70 and Hsc70 including expression in the glycosphingolipid-enriched microdomain (GEM) on the cell surface and involvement in cell death. Sialic acid-binding lectin (SBL) isolated from oocytes of Rana catesbeiana is a multifunctional protein which has lectin activity, ribonuclease activity and antitumor activity. SBL has potential as a new type of anticancer drug, since it causes cancer-selective induction of apoptosis by multiple signaling pathways in which RNA is its target; and the participation of the mitochondrial pathway and the endoplasmic reticulum (ER) stress-mediated pathway has been suggested. It has also been suggested that receptor(s) for SBL (SBLR) may exist in the GEM on the cell surface. In the present study, we studied the possible involvement of Hsp70 and Hsc70 in SBL-induced apoptosis. We showed that Hsp70 and Hsc70 were expressed on the P388 cell surface similar to SBLR, and their distribution in cells dramatically changed immediately prior to the execution of apoptosis following stimulation of SBL. Functional study of Hsp70 revealed that decreased expression of Hsp70 diminished the apoptosis induced by SBL. It is suggested that Hsp70 participates in the antitumor effect of SBL. PMID:24173532

TATSUTA, TAKEO; HOSONO, MASAHIRO; OGAWA, YUKIKO; INAGE, KYOKO; SUGAWARA, SHIGEKI; NITTA, KAZUO

2014-01-01

306

Complement activation in Glioblastoma multiforme pathophysiology: evidence from serum levels and presence of complement activation products in tumor tissue.  

PubMed

Inflammation plays a key role in the pathophysiology of Glioblastoma Multiforme (GBM). Here we focus on the contribution of the so far largely ignored complement system. ELISA and immunohistochemistry were combined to assess levels and localization of critical components of the initiation- and effector pathways of the complement cascade in sera and tumor tissue from GBM patients and matched controls. Serum levels of factor-B were decreased in GBM patients whereas C1q levels were increased. C1q and factor-B deposited in the tumor tissue. Deposition of C3 and C5b-9 suggests local complement activation.MBL deficiency, based on serum levels, was significantly less frequent among GBM patients compared to controls (14% vs. 33%). Therefore low levels of MBL may protect against the initiation/progression of GBM. PMID:25468776

Bouwens, T A M; Trouw, L A; Veerhuis, R; Dirven, C M F; Lamfers, M L M; Al-Khawaja, H

2015-01-15

307

Complement activation and complement control proteins in acute pancreatitis  

Microsoft Academic Search

Serum levels of the complement proteins C3, C4, C1 inhibitor (C1 INH), factor I (C3b inactivator) and factor H (BIH) and plasma levels of cleavage products of C3 (C3c) and factor B were measured in 26 patients with acute pancreatitis. Breakdown of C3 occurred in 19 patients, as shown by a reduction in C3 level and the presence of C3c.

J T Whicher; M P Barnes; A Brown; M J Cooper; R Read; G Walters; R C Williamson

1982-01-01

308

Complements and the Wound Healing Cascade: An Updated Review  

PubMed Central

Wound healing is a complex pathway of regulated reactions and cellular infiltrates. The mechanisms at play have been thoroughly studied but there is much still to learn. The health care system in the USA alone spends on average 9 billion dollars annually on treating of wounds. To help reduce patient morbidity and mortality related to abnormal or prolonged skin healing, an updated review and understanding of wound healing is essential. Recent works have helped shape the multistep process in wound healing and introduced various growth factors that can augment this process. The complement cascade has been shown to have a role in inflammation and has only recently been shown to augment wound healing. In this review, we have outlined the biology of wound healing and discussed the use of growth factors and the role of complements in this intricate pathway. PMID:23984063

Prakash, Satya

2013-01-01

309

[General properties and functioning principles of lectins in biological systems].  

PubMed

The authors give the literature review with analysis of main conceptions of lectins - their structure and functions according to state-of-the-art science and production requirements. Up-to-date definition of lectins based on last achievements of science and practice represented in the article. PMID:18421907

Lakhtin, V M; Lakhtin, M V; Afanas'ev, S S; Aleshkin, V A; Nesvizhski?, Iu V; Pospelova, V V

2008-01-01

310

Function of Serum Complement in Drinking Water Arsenic Toxicity  

PubMed Central

Serum complement function was evaluated in 125 affected subjects suffering from drinking water arsenic toxicity. Their mean duration of exposure was 7.4 ± 5.3?yrs, and the levels of arsenic in drinking water and urine samples were 216 ± 211 and 223 ± 302??g/L, respectively. The mean bactericidal activity of complement from the arsenic patients was 92% and that in the unexposed controls was 99% (P < 0.01), but heat-inactivated serum showed slightly elevated activity than in controls. In patients, the mean complement C3 was 1.56?g/L, and C4 was 0.29?g/L compared to 1.68?g/L and 0.25?g/L, respectively, in the controls. The mean IgG in the arsenic patients was 24.3?g/L that was highly significantly elevated (P < 0.001). Arsenic patients showed a significant direct correlation between C3 and bactericidal activity (P = 0.014). Elevated levels of C4 indicated underutilization and possibly impaired activity of the classical complement pathway. We conclude reduced function of serum complement in drinking water arsenic toxicity. PMID:22545044

Islam, Laila N.; Zahid, M. Shamim Hasan; Nabi, A. H. M. Nurun; Hossain, Mahmud

2012-01-01

311

Blocking properdin, the alternative pathway and anaphylatoxin receptors ameliorates renal ischemia reperfusion injury in decay-accelerating factor and CD59 double knockout mice1  

PubMed Central

Complement is implicated in the pathogenesis of ischemia reperfusion injury (IRI). The activation pathway(s) and effectors(s) of complement in IRI may be organ-specific and remain to be fully characterized. We previously developed a renal IRI model in decay-accelerating factor (DAF) and CD59 double knockout (DAF?/?CD59?/?) mice. Here we used this model to dissect the pathway(s) by which complement is activated in renal IRI and to evaluate whether C3a or C5a receptor (C3aR, C5aR)-mediated inflammation or the membrane attack complex (MAC) was pathogenic. We crossed DAF?/?CD59?/? mice with mice deficient in various complement components or receptors including C3, C4, factor B (fB), factor properdin (fP), mannose-binding lectin (MBL), C3aR and C5aR or immunoglobulin (Ig) and assessed renal IRI in the resulting mutant strains. We found that deletion of C3, fB, fP, C3aR or C5aR significantly ameliorated renal IRI in DAF?/?CD59?/? mice, whereas deficiency of C4, Ig, or MBL had no effect. Treatment of DAF?/?CD59?/? mice with an anti-C5 mAb reduced renal IRI to a greater degree than C5aR deficiency. We also generated and tested a function-blocking anti-mouse fP mAb and showed it to ameliorate renal IRI when given to DAF?/?CD59?/? mice 24 hr before, but not 4 or 8 hrs after, ischemia/reperfusion. These results suggest that complement is activated via the alternative pathway during the early phase of reperfusion and both anaphylatoxin-mediated inflammation and the MAC contribute to tissue injury. Further, they demonstrate a critical role of properdin and support its therapeutic targeting in renal IRI. PMID:23427256

Miwa, Takashi; Sato, Sayaka; Gullipalli, Damodare; Nangaku, Masaomi; Song, Wen-Chao

2013-01-01

312

Structure-function relationship of monocot mannose-binding lectins.  

PubMed Central

The monocot mannose-binding lectins are an extended superfamily of structurally and evolutionarily related proteins, which until now have been isolated from species of the Amaryllidaceae, Alliaceae, Araceae, Orchidaceae, and Liliaceae. To explain the obvious differences in biological activities, the structure-function relationships of the monocot mannose-binding lectins were studied by a combination of glycan-binding studies and molecular modeling using the deduced amino acid sequences of the currently known lectins. Molecular modeling indicated that the number of active mannose-binding sites per monomer varies between three and zero. Since the number of binding sites is fairly well correlated with the binding activity measured by surface plasmon resonance, and is also in good agreement with the results of previous studies of the biological activities of the mannose-binding lectins, molecular modeling is of great value for predicting which lectins are best suited for a particular application. PMID:8972598

Barre, A; Van Damme, E J; Peumans, W J; Rougé, P

1996-01-01

313

Central action of Araucaria angustifolia seed lectin in mice.  

PubMed

Possible central nervous system effects of the gymnosperm lectin from Araucaria angustifolia seeds were studied in seizure and open field tests. Male Swiss mice were administered saline (control), lectin (0.1, 1, and 10 mg/kg), flumazenil (1 mg/kg), or diazepam (1 mg/kg) intraperitoneally. Lectin at the highest dose increased time to death in the pentylenetetrazole- and strychnine-induced seizure models as compared with control, but not in the pilocarpine model. In the open field test, lectin reduced locomotor activity at all doses tested, as did diazepam, when compared with control. These locomotor effects were reversed by flumazenil pretreatment. In conclusion, A. angustifolia lectin had a protective effect in the pentylenetetrazole- and strychnine-induced seizure models, suggestive of activity in the GABAergic and glycinergic systems, respectively, and also caused a reduction in animal movements, which was reversed by flumazenil, pointing to a depressant action mediated by a GABAergic mechanism. PMID:19446042

Vasconcelos, Silvânia Maria Mendes; Lima, Silvane R; Soares, Paula Matias; Assreuy, Ana Maria Sampaio; de Sousa, Francisca Cléa Florenço; Lobato, Rodrigo de Freitas Guimarăes; Vasconcelos, Germana Silva; Santi-Gadelha, Tatiane; Bezerra, Eduardo Henrique Salviano; Cavada, Benildo Sousa; Patrocínio, Manoel Cláudio Azevedo

2009-07-01

314

Diversified Carbohydrate-Binding Lectins from Marine Resources  

PubMed Central

Marine bioresources produce a great variety of specific and potent bioactive molecules including natural organic compounds such as fatty acids, polysaccharides, polyether, peptides, proteins, and enzymes. Lectins are also one of the promising candidates for useful therapeutic agents because they can recognize the specific carbohydrate structures such as proteoglycans, glycoproteins, and glycolipids, resulting in the regulation of various cells via glycoconjugates and their physiological and pathological phenomenon through the host-pathogen interactions and cell-cell communications. Here, we review the multiple lectins from marine resources including fishes and sea invertebrate in terms of their structure-activity relationships and molecular evolution. Especially, we focus on the unique structural properties and molecular evolution of C-type lectins, galectin, F-type lectin, and rhamnose-binding lectin families. PMID:22312473

Ogawa, Tomohisa; Watanabe, Mizuki; Naganuma, Takako; Muramoto, Koji

2011-01-01

315

Mitogenic effect of Parkia speciosa seed lectin on human lymphocytes.  

PubMed

Mitogenic activity of a lectin, purified from Parkia speciosa seeds, on the isolated peripheral blood lymphocytes taken from normal blood donors and patients with esophageal carcinoma was examined using [3H]thymidine incorporation. The lectin increases the incorporation of [3H]thymidine into DNA of human lymphocytes. The activity of the lectin increased as its concentration was increased and then declined once the concentration passed an optimum point. The stimulant effect was also expressed using a proliferation index (PI): the ratio of [3H]thymidine incorporated into lymphocytes in the presence and absence of the lectin. The mitogenic activity of the lectin is comparable to those of the known T-cell mitogens, such as concanavalin A, phytohaemagglutinin, and pokeweed mitogen. Only slightly less responsiveness was observed in the case of lymphocytes from esophageal cancer compared to lymphocytes from normal donors. PMID:11199124

Suvachittanont, W; Jaranchavanapet, P

2000-12-01

316

A Chitin-Binding Lectin from Stinging Nettle Rhizomes with Antifungal Properties  

Microsoft Academic Search

Rhizomes of stinging nettle contain a small-sized lectin that exhibits binding specificity toward chitin. This lectin inhibits growth of several phytopathogenic and saprophytic chitin-containing fungi in vitro. The antifungal action of the nettle lectin differs from the action of chitinases, which are a ubiquitous class of antifungal plant proteins. Moreover, the nettle lectin acts synergistically with chitinase in inhibiting fungal

Willem F. Broekaert; Jan van Parijs; Frederik Leyns; Henk Joos; Willy J. Peumans

1989-01-01

317

Biological Properties and Characterization of Lectin from Red Kidney Bean (Phaseolus Vulgaris)  

Microsoft Academic Search

Red kidney beans (Phaseolus vulgaris) contain significant amounts of lectins which have both beneficial and detrimental biological properties. Lectins are carbohydrate-binding glycoproteins that can react specifically with human blood cells, preferentially agglutinate malignant cells, and undergo mitogenic stimulation of lymphocytes. Some lectins are resistant to heat and proteolytic enzymes and can enter the circulatory system intact. Phytohaemagglutinin (PHA)—a lectin isolated

Jianshe Zhang; John Shi; Sanja Ilic; Sophia Jun Xue; Yukio Kakuda

2008-01-01

318

Plant Lectins as Part of the Plant Defense System Against Insects  

Microsoft Academic Search

Many plants contain carbohydrate-binding proteins which are commonly designated as lectins. It is believed that some of these lectins play a role in plant defense against insects. This chapter gives an overview of the state of the art in the field of plant lectin research and highlights the most important results with regard to the insecticidal activity of plant lectins

Els J. M. Van Damme

319

On the Functional Overlap between Complement and Anti-Microbial Peptides.  

PubMed

Intriguingly, activated complement and anti-microbial peptides share certain functionalities; lytic, phagocytic, and chemo-attractant activities and each may, in addition, exert cell instructive roles. Each has been shown to have distinct LPS detoxifying activity and may play a role in the development of endotoxin tolerance. In search of the origin of complement, a functional homolog of complement C3 involved in opsonization has been identified in horseshoe crabs. Horseshoe crabs possess anti-microbial peptides able to bind to acyl chains or phosphate groups/saccharides of endotoxin, LPS. Complement activity as a whole is detectable in marine invertebrates. These are also a source of anti-microbial peptides with potential pharmaceutical applicability. Investigating the locality for the production of complement pathway proteins and their role in modulating cellular immune responses are emerging fields. The significance of local synthesis of complement components is becoming clearer from in vivo studies of parenchymatous disease involving specifically generated, complement-deficient mouse lines. Complement C3 is a central component of complement activation. Its provision by cells of the myeloid lineage varies. Their effector functions in turn are increased in the presence of anti-microbial peptides. This may point to a potentiating range of activities, which should serve the maintenance of health but may also cause disease. Because of the therapeutic implications, this review will consider closely studies dealing with complement activation and anti-microbial peptide activity in acute inflammation (e.g., dialysis-related peritonitis, appendicitis, and ischemia). PMID:25646095

Zimmer, Jana; Hobkirk, James; Mohamed, Fatima; Browning, Michael J; Stover, Cordula M

2014-01-01

320

The amino-acid sequence of multiple lectins of the acorn barnacle Megabalanus rosa and its homology with animal lectins.  

PubMed

The amino-acid sequence of a lectin isolated from the coelomic fluid of the acorn barnacle Megabalanus rosa has been determined. The lectin (Mr 140,000) is a multimeric protein whose subunit consists of 173 amino acids and one carbohydrate chain attached to Asn-39. The amino-acid sequence was determined by the manual sequencing of peptides derived from the protein by digestion with Staphylococcus aureus V8 proteinase, lysine endopeptidase and chymotrypsin, as well as fragments produced by cleavage with cyanogen bromide. The amino-acid sequence of the lectin was compared with the sequence of one (Mr 64,000) of the multiple lectins of M. rosa. They are distinct molecules in spite of a significant homology in their amino-acid sequences. The amino-acid sequence includes some regions homologous to those in other invertebrate lectins, such as sea urchin and flesh fly lectins, and vertebrate lectins. This is the first report to show the amino-acid sequence of multiple lectins isolated from an invertebrate. PMID:2354200

Muramoto, K; Kamiya, H

1990-05-31

321

The Liverwort Contains a Lectin That Is Structurally and Evolutionary Related to the Monocot Mannose-Binding Lectins1  

PubMed Central

A mannose (Man)-binding lectin has been isolated and characterized from the thallus of the liverwort Marchantia polymorpha. N-terminal sequencing indicated that the M. polymorpha agglutinin (Marpola) shares sequence similarity with the superfamily of monocot Man-binding lectins. Searches in the databases yielded expressed sequence tags encoding Marpola. Sequence analysis, molecular modeling, and docking experiments revealed striking structural similarities between Marpola and the monocot Man-binding lectins. Activity and specificity studies further indicated that Marpola is a much stronger agglutinin than the Galanthus nivalis agglutinin and exhibits a preference for methylated Man and glucose, which is unprecedented within the family of monocot Man-binding lectins. The discovery of Marpola allows us, for the first time, to corroborate the evolutionary relationship between a lectin from a lower plant and a well-established lectin family from flowering plants. In addition, the identification of Marpola sheds a new light on the molecular evolution of the superfamily of monocot Man-binding lectins. Beside evolutionary considerations, the occurrence of a G. nivalis agglutinin homolog in a lower plant necessitates the rethinking of the physiological role of the whole family of monocot Man-binding lectins. PMID:12114560

Peumans, Willy J.; Barre, Annick; Bras, Julien; Rougé, Pierre; Proost, Paul; Van Damme, Els J.M.

2002-01-01

322

Utilization of lectin-histochemistry in forensic neuropathology: lectin staining provides useful information for postmortem diagnosis in forensic neuropathology  

Microsoft Academic Search

We have investigated the deposition of glycoconjugates in human brain tissue with or without brain disorders. In this review we describe the application of lectin-histochemistry techniques to forensic neuropathology. Lectin staining is able to reveal several kinds of carbohydrate-related depositions in addition to the conventional degenerative changes including senile plaques, neurofibrillary tangles and corpora amylacea. The senile plaques and neurofibrillary

Katsuji Nishi; Akio Tanegashima; Yoshio Yamamoto; Ikuko Ushiyama; Keiko Ikemoto; Shigeru Yamasaki; Akiyoshi Nishimura; Steven Rand; Bernd Brinkmann

2003-01-01

323

Genetic complementation in apicomplexan parasites  

PubMed Central

A robust forward genetic model for Apicomplexa could greatly enhance functional analysis of genes in these important protozoan pathogens. We have developed and successfully tested a genetic complementation strategy based on genomic insertion in Toxoplasma gondii. Adapting recombination cloning to genomic DNA, we show that complementing sequences can be shuttled between parasite genome and bacterial plasmid, providing an efficient tool for the recovery and functional assessment of candidate genes. We show complementation, gene cloning, and biological verification with a mutant parasite lacking hypoxanthine-xanthine-guanine phosphoribosyltransferase and a T. gondii cDNA library. We also explored the utility of this approach to clone genes based on function from other apicomplexan parasites using Toxoplasma as a surrogate. A heterologous library containing Cryptosporidium parvum genomic DNA was generated, and we identified a C. parvum gene coding for inosine 5-monophosphate-dehydrogenase (IMPDH). Interestingly, phylogenetic analysis demonstrates a clear eubacterial origin of this gene and strongly suggests its lateral transfer from ?-proteobacteria. The prokaryotic origin of this enzyme might make it a promising target for therapeutics directed against Cryptosporidium. PMID:11959921

Striepen, Boris; White, Michael W.; Li, Catherine; Guerini, Michael N.; Malik, S.-Banoo; Logsdon, John M.; Liu, Chang; Abrahamsen, Mitchell S.

2002-01-01

324

Molecular modeling of lectin-like protein from Acacia farnesiana reveals a possible anti-inflammatory mechanism in Carrageenan-induced inflammation.  

PubMed

Acacia farnesiana lectin-like protein (AFAL) is a chitin-binding protein and has been classified as phytohaemagglutinin from Phaseolus vulgaris (PHA). Legume lectins are examples for structural studies, and this family of proteins shows a remarkable conservation in primary, secondary, and tertiary structures. Lectins have ability to reduce the effects of inflammation caused by phlogistic agents, such as carrageenan (CGN). This paper explains the anti-inflammatory activity of AFAL through structural comparison with anti-inflammatory legume lectins. The AFAL model was obtained by molecular modeling and molecular docking with glycan and carrageenan were performed to explain the AFAL structural behavior and biological activity. Pisum sativum lectin was the best template for molecular modeling. The AFAL structure model is folded as a ? sandwich. The model differs from template in loop regions, number of ? strands and carbohydrate-binding site. Carrageenan and glycan bind to different sites on AFAL. The ability of AFAL binding to carrageenan can be explained by absence of the sixth ? -strand (posterior ? sheets) and two ? strands in frontal region. AFAL can inhibit pathway inflammatory process by carrageenan injection by connecting to it and preventing its entry into the cell and triggers the reaction. PMID:24490151

Abrantes, Vanessa Erika Ferreira; Matias da Rocha, Bruno Anderson; Batista da Nóbrega, Raphael; Silva-Filho, José Caetano; Teixeira, Claudener Souza; Cavada, Benildo Sousa; Gadelha, Carlos Alberto de Almeida; Ferreira, Sergio Henrique; Figueiredo, Jozi Godoy; Santi-Gadelha, Tatiane; Delatorre, Plinio

2013-01-01

325

MMBL proteins: from lectin to bacteriocin.  

PubMed

Arguably, bacteriocins deployed in warfare among related bacteria are among the most diverse proteinacous compounds with respect to structure and mode of action. Identification of the first prokaryotic member of the so-called MMBLs (monocot mannose-binding lectins) or GNA (Galanthus nivalis agglutinin) lectin family and discovery of its genus-specific killer activity in the Gram-negative bacteria Pseudomonas and Xanthomonas has added yet another kind of toxin to this group of allelopathic molecules. This novel feature is reminiscent of the protective function, on the basis of antifungal, insecticidal, nematicidal or antiviral activity, assigned to or proposed for several of the eukaryotic MMBL proteins that are ubiquitously distributed among monocot plants, but also occur in some other plants, fish, sponges, amoebae and fungi. Direct bactericidal activity can also be effected by a C-type lectin, but this is a mammalian protein that limits mucosal colonization by Gram-positive bacteria. The presence of two divergent MMBL domains in the novel bacteriocins raises questions about task distribution between modules and the possible role of carbohydrate binding in the specificity of target strain recognition and killing. Notably, bacteriocin activity was also demonstrated for a hybrid MMBL protein with an accessory protease-like domain. This association with one or more additional modules, often with predicted peptide-hydrolysing or -binding activity, suggests that additional bacteriotoxic proteins may be found among the diverse chimaeric MMBL proteins encoded in prokaryotic genomes. A phylogenetic survey of the bacterial MMBL modules reveals a mosaic pattern of strongly diverged sequences, mainly occurring in soil-dwelling and rhizosphere bacteria, which may reflect a trans-kingdom acquisition of the ancestral genes. PMID:23176516

Ghequire, Maarten G K; Loris, Remy; De Mot, René

2012-12-01

326

Fluorescent carbohydrate probes for cell lectins  

NASA Astrophysics Data System (ADS)

Fluorescein labeled carbohydrate (Glyc) probes were synthesized as analytical tools for the study of cellular lectins, i.e. SiaLe x-PAA-flu, Sia 2-PAA-flu, GlcNAc 2-PAA-flu, LacNAc-PAA-flu and a number of similar ones, with PAA a soluble polyacrylamide carrier. The binding of SiaLe x-PAA-flu was assessed using CHO cells transfected with E-selectin, and the binding of Sia 2-PAA-flu was assessed by COS cells transfected with siglec-9. In flow cytometry assays, the fluorescein probes demonstrated a specific binding to the lectin-transfected cells that was inhibited by unlabeled carbohydrate ligands. The intense binding of SiaLe x-PAA- 3H to the E-selectin transfected cells and the lack of binding to both native and permeabilized control cells lead to the conclusion that the polyacrylamide carrier itself and the spacer arm connecting the carbohydrate moiety with PAA did not contribute anymore to the binding. Tumors were obtained from nude mice by injection of CHO E-selectin or mock transfected cells. The fluorescent SiaLe x-PAA-flu probe could bind to the tumor sections from E-selectin positive CHO cells, but not from the control ones. Thus, these probes can be used to reveal specifically the carbohydrate binding sites on cells in culture as well as cells in tissue sections. The use of the confocal spectral imaging technique with Glyc-PAA-flu probes offered the unique possibility to detect lectins in different cells, even when the level of lectin expression was rather low. The confocal mode of spectrum recording provided an analysis of the probe localization with 3D submicron resolution. The spectral analysis (as a constituent part of the confocal spectral imaging technique) enabled interfering signals of the probe and intrinsic cellular fluorescence to be accurately separated, the distribution of the probe to be revealed and its local concentration to be measured.

Galanina, Oxana; Feofanov, Alexei; Tuzikov, Alexander B.; Rapoport, Evgenia; Crocker, Paul R.; Grichine, Alexei; Egret-Charlier, Marguerite; Vigny, Paul; Le Pendu, Jacques; Bovin, Nicolai V.

2001-09-01

327

Lower mannose-binding lectin contributes to deleterious H1N1 2009 infection in children.  

PubMed

Mannose-binding lectin (MBL) has broad range of activity against viruses through the mechanisms of neutralization, opsonization, and complement activation. Prior studies have demonstrated that MBL inactivated the season's influenza virus. Due to the fact that children have no neutralizing antibody against H1N1 2009 virus, innate immunity may be crucial in the defense against influenza. Therefore, we studied whether MBL levels played a role in H1N1 2009 infection in children. In a prospective survey, we revealed that MBL levels in ICU influenza cases were significantly lower than in children with influenza from infection disease ward. MBL may be involved in innate immune responses to H1N1 2009 infection in children. PMID:23755909

Gao, Lailong; Shang, Shiqiang; Zhang, Chenmei; Tong, Meiqin; Chen, Yinghu

2014-02-01

328

The role of complement in ocular pathology  

PubMed Central

Functionally active complement system and complement regulatory proteins are present in the normal human and rodent eye. Complement activation and its regulation by ocular complement regulatory proteins contribute to the pathology of various ocular diseases including keratitis, uveitis and age-related macular degeneration. Furthermore, a strong relationship between age-related macular degeneration and polymorphism in the genes of certain complement components/complement regulatory proteins is now well established. Recombinant forms of the naturally occurring complement regulatory proteins have been exploited in the animal models for treatment of these ocular diseases. It is hoped that in the future recombinant complement regulatory proteins will be used as novel therapeutic agents in the clinic for the treatment of keratitis, uveitis, and age-related macular degeneration. PMID:18299835

Jha, Purushottam; Bora, Puran S.

2008-01-01

329

The Complement System and Ocular Diseases  

PubMed Central

In the normal eye, the complement system is continuously activated at low levels and both membrane-bound and soluble intraocular complement regulatory proteins tightly regulate this spontaneous complement activation. This allows protection against pathogens without causing any damage to self-tissue and vision loss. The complement system and complement regulatory proteins control the intraocular inflammation in autoimmune uveitis and play an important role in the development of corneal inflammation, age-related macular degeneration and diabetic retinopathy. The evidence derived from both animal models and patient studies support the concept that complement inhibition is a relevant therapeutic target in the treatment of various ocular diseases. Currently, several clinical trials using complement inhibitors are going on. It is possible that, in the near future, complement inhibitors might be used as therapeutic agents in eye clinics. PMID:17768108

Jha, Purushottam; Bora, Puran S.; Bora, Nalini S.

2007-01-01

330

A jacalin-related lectin-like gene in wheat is a component of the plant defence system  

PubMed Central

Jacalin-related lectins (JRLs) are a subgroup of proteins with one or more jacalin-like lectin domains. Although JRLs are often associated with biotic or abiotic stimuli, their biological functions in plants, as well as their relationships to plant disease resistance, are poorly understood. A mannose-specific JRL (mJRL)-like gene (TaJRLL1) that is mainly expressed in stem and spike and encodes a protein with two jacalin-like lectin domains was identified in wheat. Pathogen infection and phytohormone treatments induced its expression; while application of the salicylic acid (SA) biosynthesis inhibitor paclobutrazol and the jasmonic acid (JA) biosynthesis inhibitor diethyldithiocarbamic acid, respectively, substantially inhibited its expression. Attenuating TaJRLL1 through virus-induced gene silencing increased susceptibility to the facultative fungal pathogen Fusarium graminearum and the biotrophic fungal pathogen Blumeria graminis. Arabidopsis thaliana transformed with TaJRLL1 displayed increased resistance to F. graminearum and Botrytis cinerea. JA and SA levels in transgenic Arabidopsis increased significantly. A loss or increase of disease resistance due to an alteration in TaJRLL1 function was correlated with attenuation or enhancement of the SA- and JA-dependent defence signalling pathways. These results suggest that TaJRLL1 could be a component of the SA- and JA-dependent defence signalling pathways. PMID:21862481

Xiang, Yang; Song, Min; Wei, Zhaoyan; Tong, Jianhua; Zhang, Lixia; Xiao, Langtao; Ma, Zhengqiang; Wang, Yun

2011-01-01

331

A jacalin-related lectin-like gene in wheat is a component of the plant defence system.  

PubMed

Jacalin-related lectins (JRLs) are a subgroup of proteins with one or more jacalin-like lectin domains. Although JRLs are often associated with biotic or abiotic stimuli, their biological functions in plants, as well as their relationships to plant disease resistance, are poorly understood. A mannose-specific JRL (mJRL)-like gene (TaJRLL1) that is mainly expressed in stem and spike and encodes a protein with two jacalin-like lectin domains was identified in wheat. Pathogen infection and phytohormone treatments induced its expression; while application of the salicylic acid (SA) biosynthesis inhibitor paclobutrazol and the jasmonic acid (JA) biosynthesis inhibitor diethyldithiocarbamic acid, respectively, substantially inhibited its expression. Attenuating TaJRLL1 through virus-induced gene silencing increased susceptibility to the facultative fungal pathogen Fusarium graminearum and the biotrophic fungal pathogen Blumeria graminis. Arabidopsis thaliana transformed with TaJRLL1 displayed increased resistance to F. graminearum and Botrytis cinerea. JA and SA levels in transgenic Arabidopsis increased significantly. A loss or increase of disease resistance due to an alteration in TaJRLL1 function was correlated with attenuation or enhancement of the SA- and JA-dependent defence signalling pathways. These results suggest that TaJRLL1 could be a component of the SA- and JA-dependent defence signalling pathways. PMID:21862481

Xiang, Yang; Song, Min; Wei, Zhaoyan; Tong, Jianhua; Zhang, Lixia; Xiao, Langtao; Ma, Zhengqiang; Wang, Yun

2011-11-01

332

Lectin domains at the frontiers of plant defense  

PubMed Central

Plants are under constant attack from pathogens and herbivorous insects. To protect and defend themselves, plants evolved a multi-layered surveillance system, known as the innate immune system. Plants sense their encounters upon perception of conserved microbial structures and damage-associated patterns using cell-surface and intracellular immune receptors. Plant lectins and proteins with one or more lectin domains represent a major part of these receptors. The whole group of plant lectins comprises an elaborate collection of proteins capable of recognizing and interacting with specific carbohydrate structures, either originating from the invading organisms or from damaged plant cell wall structures. Due to the vast diversity in protein structures, carbohydrate recognition domains and glycan binding specificities, plant lectins constitute a very diverse protein superfamily. In the last decade, new types of nucleocytoplasmic plant lectins have been identified and characterized, in particular lectins expressed inside the nucleus and the cytoplasm of plant cells often as part of a specific plant response upon exposure to different stress factors or changing environmental conditions. In this review, we provide an overview on plant lectin motifs used in the constant battle against pathogens and predators during plant defenses. PMID:25165467

Lannoo, Nausicaä; Van Damme, Els J. M.

2014-01-01

333

Isolation and characterization of a lectin from Japanese mottled beans.  

PubMed

A 64-kDa dimeric lectin was purified from Phaseolus vulgaris cv. Japanese mottled beans. The purification protocol involved ion exchange chromatography with Q-Sepharose and SP-Sepharose and size exclusion chromatography on Superdex 75. The lectin was adsorbed on both Q-Sepharose and SP-Sepharose columns. Finally, the lectin gave a sharp absorbance peak which corresponded to 64 kDa based on results of size exclusion chromatography. Sodium dodecyl sulphate- polyacrylamide gel electrophoresis displayed a single band at around 32 kDa, indicating that the protein was dimeric. The hemagglutination inhibition assay indicated that the lectin showed specificity toward galactose. The lectin preserved hemagglutinating activity below 70 °C and at a pH range 3 - 12. The lectin was able to inhibit proliferation of MCF-7 cells and Hep G2 cells and possessed antifungal activity toward Mycosphaeralla arachidicola with an IC50 value of 3.9 µM. The activity of HIV-1 reverse transcriptase was reduced by 61.9 % in the presence of the lectin at 6.25 µM concentration. PMID:24654854

Zhao, Yuan; Ahmad, Ameer Maqsood; Cheung, Randy Chi Fai; Ng, Tzi Bun

2014-07-01

334

Multiple lectin detection by cell membrane affinity binding.  

PubMed

Assuming that lectins evolved to recognise relatively complex and branched oligosaccharides or parts of them, rather than simple sugars, a procedure based on lectin affinity binding to isolated erythrocyte (or any other cell type) membranes is proposed. This methodology was validated using six pure commercial lectins, as well as lectins from total protein extracts of Arbutus unedo leaves. All commercial lectins, as well as five polypeptides from A. unedo leaves bound to the glycosylated membrane receptors and were eluted by the corresponding sugars. When compared to the standard affinity chromatography procedure involving an individual sugar bound to a solid matrix, the new method provides a single-step, effective detection method for lectins and allows the rapid screening of their profile present in any unknown protein solution, indicates their biological carbohydrate affinities as well as their sugar specificities (if any), enables the simultaneous analysis of a large number of samples, does not require any pre-purification steps, permits detection of additional lectins and provides data which are more relevant from the physiological point of view. PMID:22381939

Ribeiro, Ana; Catarino, Sofia; Ferreira, Ricardo Boavida

2012-05-01

335

Characterization of a lectin from goat peripheral blood lymphocytes.  

PubMed

A D-glucose specific lectin was isolated from goat peripheral blood lymphocytes by affinity chromatography on N-acetyl D-glucosamine agarose gel. The fluorescence intensity of 4 methyl umbelliferyl D-glucose was quenched to about 62% on addition of the lectin. This lectin gave a single band corresponding to 112 kDa in SDS-PAGE irrespective of treatment with 2-mercaptoethanol. The molecular weight and the Stoke's radius of the lectin in the native conditions were found to be 114 kDa and 4.54 nm, respectively, as determined by gel filtration on Sephacryl S 500 column. The lectin was found to be a glycoprotein with 5.6% of neutral hexose content and 5.5% of sialic acid. The lectin agglutinated trypsinized rabbit erythrocytes and human type A erythrocytes. The hemagglutinating activity was dependent on the presence of divalent cations like Mn2+ and Ca2+. Optimum pH, ionic strength and temperature for rebinding of lectin to acid treated Sephadex G200 were found to be 7.5, 0.16 and 30-37 degrees C, respectively. PMID:9219437

Kayestha, R; Sumati; Hajela, K

1996-12-01

336

Lectins, agglutinins, and their roles in autoimmune reactivities.  

PubMed

Lectins are carbohydrate-binding proteins present throughout nature that act as agglutinins. Approximately 30% of our food contains lectins, some of which may be resistant enough to digestion to enter the circulation. Because of their binding properties, lectins can cause nutrient deficiencies, disrupt digestion, and cause severe intestinal damage when consumed in excess by an individual with dysfunctional enzymes. These effects are followed by disruption of intestinal barrier integrity, which is the gateway to various autoimmunities. Shared amino acid motifs between dietary lectins, exogenous peptides, and various body tissues may lead to cross-reactivity, resulting in the production of antibodies against lectin and bacterial antigens, followed by autoimmunity. The detection of immunoglobulin G (IgG) or immunoglobulin A (IgA) antibodies against specific lectins may serve as a guide for the elimination of these lectins from the diet. It is proposed that this process can reduce the peripheral antigenic stimulus and, thereby, result in a diminution of disease symptoms in some-but not all-patients with autoimmune disorders. PMID:25599185

Vojdani, Aristo

2015-01-01

337

Laetiporus sulphureus lectin and aerolysin protein family.  

PubMed

The parasitic mushroom Laetiporus sulphureus produces a family of lectins (LSL's) sharing 80-90% sequence identity that possesses a low but significant sequence similarity to the bacterial pore-forming toxins mosquitocidal toxin Mtx-2 from Bacillus sphaericus and a toxin from Clostridium septicum. The crystal structure of one member of the L. sulphureus lectins family (LSLa) reveals unexpected structural similarities to the 1-pore-forming toxins from the aerolysin family, namely, aerolysin from the Gram-negative bacterium Aeromonas hydrophila, epsilon-toxin from Clostridium perfringens and parasporin from B. thuringiensis. This similarity presumably indicates that the hemolytic activity of LSLa proceeds through a molecular mechanism that involves the formation of oligomeric transmembrane beta-barrels. Comparison of the crystal structures of the above mentioned proteins reveals common pore-forming modules, which are then distributed both in bacteria and fungi. Currently, it can be stated that the above three dimensional structures have been key in revealing structural similarities that were elusive at the sequence level. A potential corollary from this is that structural studies aimed at determining high resolution structures of aerolysin-like pore-forming toxins, whose biological activity involves large conformational changes, are mandatory to define protein domains or structural motifs with membrane-binding properties. PMID:20687481

Mancheńo, José Miguel; Tateno, Hiroaki; Sher, Daniel; Goldstein, Irwin J

2010-01-01

338

Binding of factor H to tubular epithelial cells limits interstitial complement activation in ischemic injury  

PubMed Central

Factor H is a regulator of the alternative pathway of complement. Genetic studies have revealed that patients with factor H mutations are at increased risk for several types of renal disease. Pathogenic activation of the alternative pathway in acquired diseases, such as ischemic acute kidney injury, also suggests that non-mutated factor H also has a limited ability to control the alternative pathway in the kidney. In the current study we examined the ability of circulating factor H to control alternative pathway activation on renal tubular epithelial cells. We found that an absolute deficiency of factor H prevented complement activation on the cells after ischemia/reperfusion, likely because of consumption of alternative pathway proteins in the fluid phase. In contrast, when the fluid phase regulation by factor H was retained but the interaction of factor H with cell surfaces was blocked, complement activation after renal ischemia/reperfusion increased. Finally, a recombinant form of factor H that is specifically targeted to sites of C3 deposition was found to reduce complement activation in the tubulointerstitium after I/R. These studies demonstrate that native factor H provides critical regulation of the alternative pathway in the renal tubulointerstitium after injury, but that this protection is incomplete. An inhibitor that targeted recombinant factor H to the tissue surface prevented alternative pathway activation and attenuated renal injury after I/R. PMID:21544060

Renner, Brandon; Ferreira, Viviana P.; Cortes, Claudio; Goldberg, Ryan; Ljubanovic, Danica; Pangburn, Michael K.; Pickering, Matthew C.; Tomlinson, Stephen; Holland-Neidermyer, Amanda; Strassheim, Derek; Holers, V. Michael; Thurman, Joshua M.

2011-01-01

339

Microbes bind complement inhibitor factor H via a common site.  

PubMed

To cause infections microbes need to evade host defense systems, one of these being the evolutionarily old and important arm of innate immunity, the alternative pathway of complement. It can attack all kinds of targets and is tightly controlled in plasma and on host cells by plasma complement regulator factor H (FH). FH binds simultaneously to host cell surface structures such as heparin or glycosaminoglycans via domain 20 and to the main complement opsonin C3b via domain 19. Many pathogenic microbes protect themselves from complement by recruiting host FH. We analyzed how and why different microbes bind FH via domains 19-20 (FH19-20). We used a selection of FH19-20 point mutants to reveal the binding sites of several microbial proteins and whole microbes (Haemophilus influenzae, Bordetella pertussis, Pseudomonas aeruginosa, Streptococcus pneumonia, Candida albicans, Borrelia burgdorferi, and Borrelia hermsii). We show that all studied microbes use the same binding region located on one side of domain 20. Binding of FH to the microbial proteins was inhibited with heparin showing that the common microbial binding site overlaps with the heparin site needed for efficient binding of FH to host cells. Surprisingly, the microbial proteins enhanced binding of FH19-20 to C3b and down-regulation of complement activation. We show that this is caused by formation of a tripartite complex between the microbial protein, FH, and C3b. In this study we reveal that seven microbes representing different phyla utilize a common binding site on the domain 20 of FH for complement evasion. Binding via this site not only mimics the glycosaminoglycans of the host cells, but also enhances function of FH on the microbial surfaces via the novel mechanism of tripartite complex formation. This is a unique example of convergent evolution resulting in enhanced immune evasion of important pathogens via utilization of a "superevasion site." PMID:23637600

Meri, T; Amdahl, H; Lehtinen, M J; Hyvärinen, S; McDowell, J V; Bhattacharjee, A; Meri, S; Marconi, R; Goldman, A; Jokiranta, T S

2013-01-01

340

The cytolytic C5b-9 complement complex: feedback inhibition of complement activation.  

PubMed Central

We describe a regulatory function of the terminal cytolytic C5b-9 complex [C5b-9(m)] of human complement. Purified C5b-9(m) complexes isolated from target membranes, whether in solution or bound to liposomes, inhibited lysis of sensitized sheep erythrocytes by whole human serum in a dose-dependent manner. C9 was not required for the inhibitory function since C5b-7 and C5b-8 complexes isolated from membranes were also effective. No effect was found with the cytolytically inactive, fluid-phase SC5b-9 complex. However, tryptic modification of SC5b-9 conferred an inhibitory capacity to the complex, due probably to partial removal of the S protein. Experiments using purified components demonstrated that C5b-9(m) exerts a regulatory effect on the formation of the classical- and alternative-pathway C3 convertases and on the utilization of C5 by cell-bound C5 convertases. C5b-9(m) complexes were unable to inhibit the lysis of cells bearing C5b-7(m) by C8 and C9. Addition of C5b-9(m) to whole human serum abolished its bactericidal effect on the serum-sensitive Escherichia coli K-12 strain W 3110 and suppressed its hemolytic function on antibody-sensitized, autologous erythrocytes. Feedback inhibition by C5b-9(m) represents a biologically relevant mechanism through which complement may autoregulate its effector functions. Images PMID:3162317

Bhakdi, S; Maillet, F; Muhly, M; Kazatchkine, M D

1988-01-01

341

Regulation of complement and modulation of its activity in monoclonal antibody therapy of cancer.  

PubMed

The complement system is a powerful tool of the innate immune system to eradicate pathogens. Both in vitro and in vivo evidence indicates that therapeutic anti-tumor monoclonal antibodies (mAbs) can activate the complement system by the classical pathway. However, the contribution of complement to the efficacy of mAbs is still debated, mainly due to the lack of convincing data in patients. A beneficial role for complement during mAb therapy is supported by the fact that cancer cells often upregulate complement-regulatory proteins (CRPs). Polymorphisms in various CRPs were previously associated with complement-mediated disorders. In this review the role of complement in anti-tumor mAb therapy will be discussed with special emphasis on strategies aiming at modifying complement activity. In the future, clinical efficacy of mAbs with enhanced effector functions together with comprehensive analysis of polymorphisms in CRPs in mAb-treated patients will further clarify the role of complement in mAb therapy. PMID:25517299

Meyer, Saskia; Leusen, Jeanette H W; Boross, Peter

2014-01-01

342

Immunoglobulin prevents complement-mediated hyperacute rejection in swine-to-primate xenotransplantation.  

PubMed

Immunoglobulins regulate the complement system by activating complement on foreign surfaces and diverting reactive complement proteins away from autologous cell surfaces. Based on this model, we explored the ability of Ig to balance complement activation versus control in a pig-to-primate cardiac xenotransplantation model in which the binding of xenoreactive antibodies of the recipient to graft blood vessels and the activation of complement cause hyperacute rejection. Human IgG added to human serum caused a dose-dependent decrease in deposition of iC3b, cytotoxicity, and heparan sulfate release when the serum was incubated with porcine endothelial cells. This decrease was not caused by alteration in antibody binding or consumption of complement but presumably reflected decreased formation of C3 convertase on the endothelial cells. Infusion of purified human IgG into nonhuman primates prevented hyperacute rejection of porcine hearts transplanted into the primates. As expected, the transplants contained deposits of recipient Ig and C1q but not other complement components. The inhibition of complement on endothelial cell surfaces and in the xenotransplantation model supports the idea that IgG regulates the classical complement pathway and supports therapeutic use of that agent in humoral-mediated disease. PMID:7593628

Magee, J C; Collins, B H; Harland, R C; Lindman, B J; Bollinger, R R; Frank, M M; Platt, J L

1995-11-01

343

The Role of Complement in EAE  

Microsoft Academic Search

The complement system is an essential effector of the humoral and cellular immunity involved in cytolysis and immune\\/inflammatory\\u000a responses. Complement participates in host defence against pathogens by triggering the formation of the membrane attack complex.\\u000a Complement opsonins (Clq, C3b, iC3b) interact with surface complement receptors to promote phagocytosis while complement anaphylatoxins\\u000a C3a and C5a initiate local pro-inflammatory responses that, ultimately,

Johan van Beek; B. Paul Morgan

344

Zinc binding to the Tyr402 and His402 allotypes of complement factor H: possible implications for age-related  

E-print Network

1 Zinc binding to the Tyr402 and His402 allotypes of complement factor H: possible implications of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK Running Title: Zinc binding of the alternative pathway of complement activation. High millimolar concentrations of zinc are found in drusen

Martin, Andrew C.R.

345

Immature recent thymic emigrants are eliminated by complement.  

PubMed

Recent thymic emigrants (RTEs) must undergo phenotypic and functional maturation to become long-lived mature naive T cells. In CD4-cre NKAP conditional knockout mice, NKAP-deficient RTEs fail to complete T cell maturation. In this study, we demonstrate that NKAP-deficient immature RTEs do not undergo apoptosis, but are eliminated by complement. C3, C4, and C1q are bound to NKAP-deficient peripheral T cells, demonstrating activation of the classical arm of the complement pathway. As thymocytes mature and exit to the periphery, they increase sialic acid incorporation into cell surface glycans. This is essential to peripheral lymphocyte survival, as stripping sialic acid with neuraminidase leads to the binding of natural IgM and complement fixation. NKAP-deficient T cells have a defect in sialylation on cell surface glycans, leading to IgM recruitment. We demonstrate that the defect in sialylation is due to aberrant ?2,8-linked sialylation, and the expression of three genes (ST8sia1, ST8sia4, and ST8sia6) that mediate ?2,8 sialylation are downregulated in NKAP-defcient RTEs. The maturation of peripheral NKAP-deficient T cells is partially rescued in a C3-deficient environment. Thus, sialylation during T cell maturation is critical to protect immature RTEs from complement in the periphery. PMID:25367120

Hsu, Fan-Chi; Shapiro, Michael J; Chen, Meibo W; McWilliams, Douglas C; Seaburg, Lauren M; Tangen, Sarah N; Shapiro, Virginia Smith

2014-12-15

346

Membrane protein Crry maintains homeostasis of the complement system1  

PubMed Central

Complement activation is tightly regulated to avoid excessive inflammatory and immune responses. Crry-/- is an embryonic lethal phenotype secondary to the maternal complement alternative pathway (AP) attacking a placenta deficient in this inhibitor. In this study, we demonstrate that Crry-/- mice could be rescued on a partial as well as on a complete factor B (fB)- or C3-deficient maternal background. The C3 and fB protein concentrations in Crry-/-C3+/- and Crry-/-fB+/- mice were substantially reduced for gene dosage secondary to enhanced AP turnover. Based on these observations, a breeding strategy featuring reduced maternal AP-activating capacity rescued the lethal phenotype. It led to a novel, stable line of Crry SKO mice carrying normal alleles for C3 and fB. Crry SKO mice also had accelerated C3 and fB turnover and therefore reduced AP-activating potential. These instructive results represent an example of a membrane regulatory protein being responsible for homeostasis of the complement system. They imply that there is constant turnover on cells of the AP pathway which functions as an immune surveillance system for pathogens and altered self. PMID:18684964

Wu, Xiaobo; Spitzer, Dirk; Mao, Dailing; Peng, Stanford L.; Molina, Hector; Atkinson, John P.

2008-01-01

347

Distribution and Evolution of the Lectin Family in Soybean (Glycine max).  

PubMed

Lectins are a diverse group of proteins that bind specific carbohydrates and are found throughout all kingdoms. In plants, lectins are involved in a range of important processes such as plant defense and stress signaling. Although the genome sequence of Glycine max (soybean) has been published, little is known about the abundance and expansion patterns of lectin genes in soybean. Using BLAST and hidden Markov models, a total of 359 putative lectin genes have been identified. Furthermore, these sequences could be classified in nine of the twelve plant lectin families identified today. Analysis of the domain organization demonstrated that most of the identified lectin genes encode chimerolectins, consisting of one or multiple lectin domains combined with other known protein domains. Both tandem and segmental duplication events have contributed to the expansion of the lectin gene family. These data provide a detailed understanding of the domain architecture and molecular evolution of the lectin gene family in soybean. PMID:25679048

Van Holle, Sofie; Van Damme, Els J M

2015-01-01

348

The pivotal role of the complement system in aging and age-related macular degeneration: hypothesis re-visited.  

PubMed

During the past ten years, dramatic advances have been made in unraveling the biological bases of age-related macular degeneration (AMD), the most common cause of irreversible blindness in western populations. In that timeframe, two distinct lines of evidence emerged which implicated chronic local inflammation and activation of the complement cascade in AMD pathogenesis. First, a number of complement system proteins, complement activators, and complement regulatory proteins were identified as molecular constituents of drusen, the hallmark extracellular deposits associated with early AMD. Subsequently, genetic studies revealed highly significant statistical associations between AMD and variants of several complement pathway-associated genes including: Complement factor H (CFH), complement factor H-related 1 and 3 (CFHR1 and CFHR3), complement factor B (CFB), complement component 2 (C2), and complement component 3 (C3). In this article, we revisit our original hypothesis that chronic local inflammatory and immune-mediated events at the level of Bruch's membrane play critical roles in drusen biogenesis and, by extension, in the pathobiology of AMD. Secondly, we report the results of a new screening for additional AMD-associated polymorphisms in a battery of 63 complement-related genes. Third, we identify and characterize the local complement system in the RPE-choroid complex - thus adding a new dimension of biological complexity to the role of the complement system in ocular aging and AMD. Finally, we evaluate the most salient, recent evidence that bears directly on the role of complement in AMD pathogenesis and progression. Collectively, these recent findings strongly re-affirm the importance of the complement system in AMD. They lay the groundwork for further studies that may lead to the identification of a transcriptional disease signature of AMD, and hasten the development of new therapeutic approaches that will restore the complement-modulating activity that appears to be compromised in genetically susceptible individuals. PMID:19961953

Anderson, Don H; Radeke, Monte J; Gallo, Natasha B; Chapin, Ethan A; Johnson, Patrick T; Curletti, Christy R; Hancox, Lisa S; Hu, Jane; Ebright, Jessica N; Malek, Goldis; Hauser, Michael A; Rickman, Catherine Bowes; Bok, Dean; Hageman, Gregory S; Johnson, Lincoln V

2010-03-01

349

The Pivotal Role of the Complement System in Aging and Age-related Macular Degeneration: Hypothesis Re-visited  

PubMed Central

During the past ten years, dramatic advances have been made in unraveling the biological bases of age-related macular degeneration (AMD), the most common cause of irreversible blindness in western populations. In that timeframe, two distinct lines of evidence emerged which implicated chronic local inflammation and activation of the complement cascade in AMD pathogenesis. First, a number of complement system proteins, complement activators, and complement regulatory proteins were identified as molecular constituents of drusen, the hallmark extracellular deposits associated with early AMD. Subsequently, genetic studies revealed highly significant statistical associations between AMD and variants of several complement pathway-associated genes including: Complement factor H (CFH), complement factor H-related 1 and 3 (CFHR1 and CFHR3), complement factor B (CFB), complement component 2 (C2), and complement component 3 (C3). In this article, we revisit our original hypothesis that chronic local inflammatory and immune-mediated events at the level of Bruch’s membrane play critical roles in drusen biogenesis and, by extension, in the pathobiology of AMD. Secondly, we report the results of a new screening for additional AMD-associated polymorphisms in a battery of 63 complement-related genes. Third, we identify and characterize the local complement system in the RPE-choroid complex -- thus adding a new dimension of biological complexity to the role of the complement system in ocular aging and AMD. Finally, we evaluate the most salient, recent evidence that bears directly on the role of complement in AMD pathogenesis and progression. Collectively, these recent findings strongly re-affirm the importance of the complement system in AMD. They lay the groundwork for further studies that may lead to the identification of a transcriptional disease signature of AMD, and hasten the development of new therapeutic approaches that will restore the complement-modulating activity that appears to be compromised in genetically susceptible individuals. PMID:19961953

Anderson, Don H.; Radeke, Monte J.; Gallo, Natasha B.; Chapin, Ethan A.; Johnson, Patrick T.; Curletti, Christy R.; Hancox, Lisa S.; Hu, Jane; Ebright, Jessica N.; Malek, Goldis; Hauser, Michael A.; Rickman, Catherine Bowes; Bok, Dean; Hageman, Gregory S.; Johnson, Lincoln V.

2009-01-01

350

21 CFR 864.9550 - Lectins and protectins.  

Code of Federal Regulations, 2012 CFR

...HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Products Used In Establishments That Manufacture...Identification. Lectins and protectins are proteins derived from plants and lower animals that cause cell agglutination in the...

2012-04-01

351

21 CFR 864.9550 - Lectins and protectins.  

Code of Federal Regulations, 2014 CFR

...HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Products Used In Establishments That Manufacture...Identification. Lectins and protectins are proteins derived from plants and lower animals that cause cell agglutination in the...

2014-04-01

352

21 CFR 864.9550 - Lectins and protectins.  

Code of Federal Regulations, 2013 CFR

...HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Products Used In Establishments That Manufacture...Identification. Lectins and protectins are proteins derived from plants and lower animals that cause cell agglutination in the...

2013-04-01

353

Lectins stain cells differentially in the coral, Montipora capitata  

USGS Publications Warehouse

A limitation in our understanding of coral disease pathology and cellular pathogenesis is a lack of reagents to characterize coral cells. We evaluated the utility of plant lectins to stain tissues of a dominant coral, Montipora capitata, from Hawaii. Of 22 lectins evaluated, nine of these stained structures in the upper or basal body wall of corals. Specific structures revealed by lectins that were not considered distinct or evident on routine hematoxylin and eosin sections of coral tissues included apical and basal granules in gastrodermis and epidermis, cnidoglandular tract and actinopharynx cell surface membranes, capsules of mature holotrichous isorhizas, and perivitelline and periseminal cells. Plant lectins could prove useful to further our understanding of coral physiology, anatomy, cell biology, and disease pathogenesis.

Work, Thierry M.; Farah, Yael

2014-01-01

354

Structure and Function of Mammalian Carbohydrate-Lectin Interactions  

NASA Astrophysics Data System (ADS)

Over the past three decades the field of glycobiology has expanded beyond a basic understanding of the structure and biosynthesis of glycoprotein, proteoglycans, and glycolipids toward a more detailed picture of how these molecules afford communication through binding to mammalian lectins. Although the number of different mammalian lectin domains appears to be finite and even much smaller than early estimates predicated based on the diversity of glycan structures, nature appears capable of using these in numerous combinations to fine tune specificity. The following provides an overview of the major classes of mammalian lectins and discusses their glycan binding specificity. The review provides a snapshot of the field of glycobiology that continues to grow providing an increasing number of examples of biological processes that rely upon glycan-lectin binding.

Anderson, Kevin; Evers, David; Rice, Kevin G.

355

Pasteurella pneumotropica Evades the Human Complement System by Acquisition of the Complement Regulators Factor H and C4BP  

PubMed Central

Pasteurella pneumotropica is an opportunist Gram negative bacterium responsible for rodent pasteurellosis that affects upper respiratory, reproductive and digestive tracts of mammals. In animal care facilities the presence of P. pneumotropica causes severe to lethal infection in immunodeficient mice, being also a potential source for human contamination. Indeed, occupational exposure is one of the main causes of human infection by P. pneumotropica. The clinical presentation of the disease includes subcutaneous abscesses, respiratory tract colonization and systemic infections. Given the ability of P. pneumotropica to fully disseminate in the organism, it is quite relevant to study the role of the complement system to control the infection as well as the possible evasion mechanisms involved in bacterial survival. Here, we show for the first time that P. pneumotropica is able to survive the bactericidal activity of the human complement system. We observed that host regulatory complement C4BP and Factor H bind to the surface of P. pneumotropica, controlling the activation pathways regulating the formation and maintenance of C3-convertases. These results show that P. pneumotropica has evolved mechanisms to evade the human complement system that may increase the efficiency by which this pathogen is able to gain access to and colonize inner tissues where it may cause severe infections. PMID:25347183

Sahagún-Ruiz, Alfredo; Granados Martinez, Adriana Patricia; Breda, Leandro Carvalho Dantas; Fraga, Tatiana Rodrigues; Castiblanco Valencia, Mónica Marcela; Barbosa, Angela Silva; Isaac, Lourdes

2014-01-01

356

New Insights of an Old Defense System: Structure, Function, and Clinical Relevance of the Complement System  

PubMed Central

The complement system was discovered a century ago as a potent defense cascade of innate immunity. After its first description, continuous experimental and clinical research was performed, and three canonical pathways of activation were established. Upon activation by traumatic or surgical tissue damage, complement reveals beneficial functions of pathogen and danger defense by sensing and clearing injured cells. However, the latest research efforts have provided a more distinct insight into the complement system and its clinical subsequences. Complement has been shown to play a significant role in the pathogenesis of various inflammatory processes such as sepsis, multiorgan dysfunction, ischemia/reperfusion, cardiovascular diseases and many others. The three well-known activation pathways of the complement system have been challenged by newer findings that demonstrate direct production of central complement effectors (for example, C5a) by serine proteases of the coagulation cascade. In particular, thrombin is capable of producing C5a, which not only plays a decisive role on pathogens and infected/damaged tissues, but also acts systemically. In the case of uncontrolled complement activation, “friendly fire” is generated, resulting in the destruction of healthy host tissue. Therefore, the traditional research that focuses on a mainly positive-acting cascade has now shifted to the negative effects and how tissue damage originated by the activation of the complement can be contained. In a translational approach including structure-function relations of this ancient defense system, this review provides new insights of complement-mediated clinical relevant diseases and the development of complement modulation strategies and current research aspects. PMID:21046060

Ehrnthaller, Christian; Ignatius, Anita; Gebhard, Florian; Huber-Lang, Markus

2011-01-01

357

Genetic variants in the complement system predisposing to age-related macular degeneration: a review.  

PubMed

Age-related macular degeneration (AMD) is a major cause of visual impairment in the western world. It is characterized by the presence of lipoproteinaceous deposits (drusen) in the inner layers of the retina. Immunohistochemistry studies identified deposition of complement proteins in the drusen as well as in the choroid. In the last decade, genetic studies have linked both common and rare variants in genes of the complement system to increased risk of development of AMD. Here, we review the variants described to date and discuss the functional implications of dysregulation of the alternative pathway of complement in AMD. PMID:25034031

Schramm, Elizabeth C; Clark, Simon J; Triebwasser, Michael P; Raychaudhuri, Soumya; Seddon, Johanna M; Atkinson, John P

2014-10-01

358

A Lectin from Dioclea violacea Interacts with Midgut Surface of Lutzomyia migonei, Unlike Its Homologues, Cratylia floribunda Lectin and Canavalia gladiata Lectin  

PubMed Central

Leishmaniasis is a vector-borne disease transmitted by phlebotomine sand fly. Susceptibility and refractoriness to Leishmania depend on the outcome of multiple interactions that take place within the sand fly gut. Promastigote attachment to sand fly midgut epithelium is essential to avoid being excreted together with the digested blood meal. Promastigote and gut sand fly surface glycans are important ligands in this attachment. The purpose of the present study was to evaluate the interaction of three lectins isolated from leguminous seeds (Diocleinae subtribe), D-glucose and D-mannose-binding, with glycans on Lutzomyia migonei midgut. To study this interaction the lectins were labeled with FITC and a fluorescence assay was performed. The results showed that only Dioclea violacea lectin (DVL) was able to interact with midgut glycans, unlike Cratylia floribunda lectin (CFL) and Canavalia gladiata lectin (CGL). Furthermore, when DVL was blocked with D-mannose the interaction was inhibited. Differences of spatial arrangement of residues and volume of carbohydrate recognition domain (CRD) may be the cause of the fine specificity of DVL for glycans in the surface on Lu. migonei midgut. The findings in this study showed the presence of glycans in the midgut with glucose/mannose residues in its composition and these residues may be important in interaction between Lu. migonei midgut and Leishmania. PMID:25431778

Monteiro Tínel, Juliana Montezuma Barbosa; Benevides, Melina Fechine Costa; Frutuoso, Mércia Sindeaux; Rocha, Camila Farias; Arruda, Francisco Vassiliepe Sousa; Vasconcelos, Mayron Alves; Pereira-Junior, Francisco Nascimento; Cajazeiras, Joăo Batista; do Nascimento, Kyria Santiago; Martins, Jorge Luiz; Teixeira, Edson Holanda; Cavada, Benildo Sousa; dos Santos, Ricardo Pires; Lima Pompeu, Margarida Maria

2014-01-01

359

[Classification of lectins as universal regulator molecules of biological systems].  

PubMed

Modern concepts of lectin classification reflecting tendencies in the development of functional classification of lectins (Ln) and Ln-like proteins are presented. Classification of bacterial Ln is proposed. Classification of Ln and Ln-like proteins of plants, animals, and bacteria is based on 8 major elements of protein secondary structure that allows for the evaluation of topographic diversity of their surfaces, potential compatibility of bacterial, vegetable, and mammalian Ln molecules and possible variants of their co-functioning. PMID:19385429

Lakhtin, V M; Afanas'ev, S S; Aleshkin, V A; Nesvizhski?, Iu V; Lakhtin, M V; Shubin, V V; Cherepanova, Iu V; Pospelova, V V

2009-01-01

360

Crystal Structure of Mistletoe Lectin I from Viscum album  

Microsoft Academic Search

The crystal structure of the ribosome-inactivating protein (RIP) mistletoe lectin I (ML-I) fromViscum albumhas been solved by molecular replacement techniques. The structure has been refined to a crystallographic R-factor of 24.5% using X-ray diffraction data to 2.8 Ĺ resolution. The heterodimeric 63-kDa protein consists of a toxic A subunit which exhibits RNA-glycosidase activity and a galactose-specific lectin B subunit. The

Ruth Krauspenhaar; Susanne Eschenburg; Markus Perbandt; Vjacheslav Kornilov; Nina Konareva; Inna Mikailova; Stanka Stoeva; Roland Wacker; Timm Maier; Tej Singh; Albert Mikhailov; Wolfgang Voelter; Christian Betzel

1999-01-01

361

The Role of Complement in Tumor Growth  

PubMed Central

Complement is a central part of the immune system that has developed as a first defense against non-self cells. Neoplastic transformation is accompanied by an increased capacity of the malignant cells to activate complement. In fact, clinical data demonstrate complement activation in cancer patients. On the basis of the use of protective mechanisms by malignant cells, complement activation has traditionally been considered part of the body's immunosurveillance against cancer. Inhibitory mechanisms of complement activation allow cancer cells to escape from complement-mediated elimination and hamper the clinical efficacy of monoclonal antibody–based cancer immunotherapies. To overcome this limitation, many strategies have been developed with the goal of improving complement-mediated effector mechanisms. However, significant work in recent years has identified new and surprising roles for complement activation within the tumor microenvironment. Recent reports suggest that complement elements can promote tumor growth in the context of chronic inflammation. This chapter reviews the data describing the role of complement activation in cancer immunity, which offers insights that may aid the development of more effective therapeutic approaches to control cancer. PMID:24272362

Pio, Ruben; Corrales, Leticia; Lambris, John D.

2015-01-01

362

Complement Activation and Inhibition in Wound Healing  

PubMed Central

Complement activation is needed to restore tissue injury; however, inappropriate activation of complement, as seen in chronic wounds can cause cell death and enhance inflammation, thus contributing to further injury and impaired wound healing. Therefore, attenuation of complement activation by specific inhibitors is considered as an innovative wound care strategy. Currently, the effects of several complement inhibitors, for example, the C3 inhibitor compstatin and several C1 and C5 inhibitors, are under investigation in patients with complement-mediated diseases. Although (pre)clinical research into the effects of these complement inhibitors on wound healing is limited, available data indicate that reduction of complement activation can improve wound healing. Moreover, medicine may take advantage of safe and effective agents that are produced by various microorganisms, symbionts, for example, medicinal maggots, and plants to attenuate complement activation. To conclude, for the development of new wound care strategies, (pre)clinical studies into the roles of complement and the effects of application of complement inhibitors in wound healing are required. PMID:23346185

Cazander, Gwendolyn; Jukema, Gerrolt N.; Nibbering, Peter H.

2012-01-01

363

Probing lectin-mucin interactions by isothermal titration microcalorimetry.  

PubMed

Isothermal titration microcalorimetry (ITC) can directly determine the thermodynamic binding parameters of biological molecules including affinity constant, binding stoichiometry, and heat of binding (enthalpy) and indirectly the entropy and free energy of binding. ITC has been extensively used to study the binding of lectins to mono- and oligosaccharides, but limited applications to lectin-glycoprotein interactions. Inherent experimental challenges to ITC include sample precipitation during the experiment and relative high amount of sample required, but careful design of experiments can minimize these problems and allow valuable information to be obtained. For example, the thermodynamics of binding of lectins to multivalent globular and linear glycoproteins (mucins) have been described. The results are consistent with a dynamic binding mechanism in which lectins bind and jump from carbohydrate to carbohydrate epitope in these molecules leading to increased affinity. Importantly, the mechanism of binding of lectins to mucins appears similar to that for a variety of protein ligands binding to DNA. Recent results also show that high affinity lectin-mucin cross-linking interactions are driven by favorable entropy of binding that is associated with the bind and jump mechanism. The results suggest that the binding of ligands to biopolymers, in general, may involve a common mechanism that involves enhanced entropic effects that facilitate binding interactions. PMID:25253134

Dam, Tarun K; Brewer, C Fred

2015-01-01

364

[Effect of exogenous lectin on the endogenous lectin and antioxidant enzymes activity and flavonoid content in wheat].  

PubMed

The presawing treatment of wheat seeds by lectin specific to the plant and its compositions with gapten and nitrogen fixation bacteria on the change in enzyme activity of antioxidant system of plant protection (peroxydase and katalase), endogenous lectin activity and flavonoid content in wheat leaves was studied in vegetation experiments. It is shown, that different biochemical links of protection plant system are activated, i.e. lectin activity in leaves increases 1.3 to 1.5 times, peroxydase activity and katalase activity rises 1.5 times and 5.0 to 8.0 times respectively and flavonoide content in leaves of vegetating plants increases under normal conditions of plant growth at the influence of factors of lectin nature. PMID:17100292

Kruhova, O D; Mandrovs'ka, N M; Kyrychenko, O V

2006-01-01

365

Myeloperoxidase influences the complement regulatory function of modified C-reactive protein.  

PubMed

In patients with active anti-neutrophil cytoplasmic Ab (ANCA)-associated vasculitis (AAV), there are high levels of circulating C-reactive protein (CRP), which can inhibit the alternative complement pathway by binding factor H and triggering the classical complement pathway by binding C1q. However, the alternative, not the classical, complement pathway has been proven to play an important role in AAV. We found that both purified myeloperoxidase (MPO) and MPO released from ANCA-stimulated neutrophils could bind modified CRP (mCRP), but not pentameric CRP. Furthermore, MPO could block the binding between mCRP and factor H, as well as the binding between mCRP and C1q. Binding with mCRP did not influence the enzymatic activity of MPO. Binding with mCRP also did not influence the binding between MPO and its physical inhibitor, ceruloplasmin, as well as the binding between MPO and MPO-ANCA. The results indicated that MPO might be a complement regulator and inhibit the negative regulatory effect of CRP on the alternative complement pathway. PMID:24189124

Xu, Peng-cheng; Li, Zhi-ying; Yang, Xiao-wei; Zhao, Ming-hui; Chen, Min

2014-05-01

366

The major tuber storage protein of araceae species is a lectin. Characterization and molecular cloning of the lectin from Arum maculatum L.  

PubMed Central

A new lectin was purified from tubers of Arum maculatum L. by affinity chromatography on immobilized asialofetuin. Although this lectin is also retained on mannose-Sepharose 4B, under the appropriate conditions free mannose is a poor inhibitor of its agglutination activity. Pure preparations of the Arum lectin apparently yielded a single polypeptide band of approximately 12 kD upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, N-terminal sequencing of the purified protein combined with molecular cloning of the lectin have shown that the lectin is composed of two different 12-kD lectin subunits that are synthesized on a single large precursor translated from an mRNA of approximately 1400 nucleotides. Lectins with similar properties were also isolated from the Araceae species Colocasia esculenta (L.) Schott, Xanthosoma sagittifolium (L.) Schott, and Dieffenbachia sequina Schott. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration of the different Araceae lectins have shown that they are tetrameric proteins composed of lectin subunits of 12 to 14 kD. Interestingly, these lectins are the most prominent proteins in the tuber tissue. Evidence is presented that a previously described major storage protein of Colocasia tubers corresponds to the lectin. PMID:7770523

Van Damme, E J; Goossens, K; Smeets, K; Van Leuven, F; Verhaert, P; Peumans, W J

1995-01-01

367

Cholesterol crystals induce complement-dependent inflammasome activation and cytokine release  

PubMed Central

Inflammation is associated with development of atherosclerosis, and cholesterol crystals (CC) have long been recognized as a hallmark of atherosclerotic lesions. CC appear early in the atheroma development and trigger inflammation by NLRP3 inflammasome activation. In this study we hypothesized whether CC employ the complement system to activate the inflammasome-caspase-1 leading to release of mature IL-1?, and if complement activation regulates CC-induced cytokine production. We here describe that CC activated both the classical and alternative complement pathways and C1q was found to be crucial for the activation. CC employed C5a in the release of a number of cytokines in whole blood, including IL-1? and TNF. CC induced minimal amounts of cytokines in C5-deficient whole blood, until reconstituted with C5. Furthermore, C5a and TNF in combination acted as a potent primer for CC-induced IL-1? release by increasing IL-1? transcripts. CC-induced complement activation resulted in up-regulation of Complement receptor 3 (CD11b/CD18) leading to phagocytosis of CC. Also, CC mounted a complement-dependent production of reactive oxygen species and active caspase-1. We conclude that CC employs the complement system to induce cytokines and activate the inflammasome-caspase-1 by regulating several cellular responses in human monocytes. In light of this, complement inhibition might be an interesting therapeutic approach for treatment of atherosclerosis. PMID:24554772

Samstad, Eivind O.; Niyonzima, Nathalie; Nymo, Stig; Aune, Marie H.; Ryan, Liv; Bakke, Siril S.; Lappegĺrd, Knut T.; Brekke, Ole-Lars; Lambris, John D.; Damĺs, Jan K.; Latz, Eicke; Mollnes, Tom E.; Espevik, Terje

2014-01-01

368

Genetic and therapeutic targeting of properdin in mice prevents complement-mediated tissue injury  

PubMed Central

The alternative pathway (AP) of complement activation is constitutively active and must be regulated by host proteins to prevent autologous tissue injury. Dysfunction of AP regulatory proteins has been linked to several human inflammatory disorders. Properdin is a positive regulator of AP complement activation that has been shown to extend the half-life of cell surface–bound C3 convertase C3bBb; it may also initiate AP complement activation. Here, we demonstrate a critical role for properdin in autologous tissue injury mediated by AP complement activation. We identified myeloid lineage cells as the principal source of plasma properdin by generating mice with global and tissue-specific knockout of Cfp (which encodes properdin) and by generating BM chimeric mice. Properdin deficiency rescued mice from AP complement–mediated embryonic lethality caused by deficiency of the membrane complement regulator Crry and markedly reduced disease severity in the K/BxN model of arthritis. Ab neutralization of properdin in WT mice similarly ameliorated arthritis development, whereas reconstitution of properdin-null mice with exogenous properdin restored arthritis sensitivity. These data implicate systemic properdin as a key contributor to AP complement–mediated injury and support its therapeutic targeting in complement-dependent human diseases. PMID:20941861

Kimura, Yuko; Zhou, Lin; Miwa, Takashi; Song, Wen-Chao

2010-01-01

369

Localization of soluble endogenous lectins and their ligands at specific extracellular sites.  

PubMed

Soluble lectins of chicken, rat, frog, and the cellular slime mold, Dictyostelium discoideum, were purified and specific antibodies raised against these proteins were used to immunohistochemically localize the lectins in and around the tissues in which they were synthesized. Within cells, some of these soluble lectins (chicken-lactose-lectin-II in intestinal goblet cells, discoidin II in prespore cells) appear to be concentrated within vesicles whereas others (e.g., rat beta-galactoside lectin in pulmonary alveolar and smooth muscle cells) appear to be free in the cytoplasm. All of these lectins are eventually secreted to extracellular sites in developing or adult tissues. The sites include mucin (chicken-lactose-lectin-II in intestine); developing extracellular matrix (chicken-lactose-lectin-I in muscle; Xenopus laevis lectin in blastula stage embryos); slime (discoidin I); developing spore coat (discoidin II); and a specialized extracellular matrix, elastic fibers (rat beta-galactoside lectin in lung). In cases where this has been studied in detail (discoidin I, discoidin II, and chicken-lactose-lectin-II), the lectin is associated with a complementary extracellular ligand, at least transiently. Lectin-ligand interactions presumably confer specialized properties in these particular extracellular domains. PMID:6240298

Barondes, S H; Cerra, R F; Cooper, D N; Haywood-Reid, P L; Roberson, M M

1984-01-01

370

High dose intravenous immunoglobulin does not affect complement-bacteria interactions.  

PubMed

Pooled IgG preparations for i.v. use (IVIg) have been shown to possess anticomplementary activity in autoimmune and systemic inflammatory diseases. Both in vitro and in vivo, IVIg is a preferential acceptor of activated C4 and C3, thus diverting complement activation from the target surface. We explored the effect of IVIg on complement-bacteria interactions in an attempt both to determine the safety of IVIg preparations in relation to natural immunity to bacteria and to extend our knowledge of the physiologic mechanism of action of IVIg. Using both complement-sensitive and complement-resistant bacterial strains, we investigated the effect of IVIg on C3 binding to bacterial surfaces. In all cases, whether complement could be directly activated by bacteria through the classical or the alternative pathway, IVIg had no effect on the amount of C3 bound to bacteria. In addition, IVIg did not inhibit complement-dependent bacterial lysis. Interestingly, increasing concentrations of IVIg induced an increase in C1q binding, suggesting the presence of low affinity complement-fixing antibacterial Abs in certain preparations. Using serum samples from patients treated with IVIg, complement binding to and lysis of complement-sensitive bacterial strains were not modified as compared with normal controls and pretreatment samples, although a decrease in C3 binding to sensitized human erythrocytes was observed. Our data suggest that IVIg does not affect direct complement-bacteria interactions, although it is a potent agent to use for diversion of complement activation on sensitized target surfaces. PMID:9469456

Wagner, E; Platt, J L; Frank, M M

1998-02-15

371

21 CFR 866.4100 - Complement reagent.  

Code of Federal Regulations, 2014 CFR

...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4100 Complement reagent. (a)...

2014-04-01

372

21 CFR 866.4100 - Complement reagent.  

Code of Federal Regulations, 2012 CFR

...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4100 Complement reagent. (a)...

2012-04-01

373

21 CFR 866.4100 - Complement reagent.  

Code of Federal Regulations, 2010 CFR

...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4100 Complement reagent. (a)...

2010-04-01

374

Complement anaphylatoxins as immune regulators in cancer  

PubMed Central

The role of the complement system in innate immunity is well characterized. However, a recent body of research implicates the complement anaphylatoxins C3a and C5a as insidious propagators of tumor growth and progression. It is now recognized that certain tumors elaborate C3a and C5a and that complement, as a mediator of chronic inflammation and regulator of immune function, may in fact foster rather than defend against tumor growth. A putative mechanism for this function is complement-mediated suppression of immune effector cells responsible for immunosurveillance within the tumor microenvironment. This paradigm accords with models of immune dysregulation, such as autoimmunity and infectious disease, which have defined a pathophysiological role for abnormal complement signaling. Several types of immune cells express the cognate receptors for the complement anaphylatoxins, C3aR and C5aR, and demonstrate functional modulation in response to complement stimulation. In turn, impairment of antitumor immunity has been intimately tied to tumor progression in animal models of cancer. In this article, the literature was systematically reviewed to identify studies that have characterized the effects of the complement anaphylatoxins on the composition and function of immune cells within the tumor microenvironment. The search identified six studies based upon models of lymphoma and ovarian, cervical, lung, breast, and mammary cancer, which collectively support the paradigm of complement as an immune regulator in the tumor microenvironment. PMID:24711204

Sayegh, Eli T; Bloch, Orin; Parsa, Andrew T

2014-01-01

375

21 CFR 866.4100 - Complement reagent.  

Code of Federal Regulations, 2013 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4100 Complement reagent. (a)...

2013-04-01

376

21 CFR 866.4100 - Complement reagent.  

Code of Federal Regulations, 2011 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunology Laboratory Equipment and Reagents § 866.4100 Complement reagent. (a)...

2011-04-01

377

Serum complement and platelet adhesiveness in acute canine ehrlichiosis  

E-print Network

In the dogs in group II, the mean daily CH5 titer did not change until after the 1st CVF injection when a marked decrease in the CH 0 titer occurred in each dog (Table 6). The mean CH titer for this 50 group was less than 50 units on day 8 and 10 PI...) by the alternate pathway. l In the present study CVF caused marked reduction in the level of serum complement activity for a period of at least 2, and possibly 5 to 6 days immediately after administration. This was followed in the group II dogs by an 8 to 13...

Lovering, Sandra Lorraine

1977-01-01

378

Characterization of the Grp94/OS-9 chaperone-lectin complex.  

PubMed

Grp94 is a macromolecular chaperone belonging to the hsp90 family and is the most abundant glycoprotein in the endoplasmic reticulum (ER) of mammals. In addition to its essential role in protein folding, Grp94 was proposed to participate in the ER-associated degradation quality control pathway by interacting with the lectin OS-9, a sensor for terminally misfolded proteins. To understand how OS-9 interacts with ER chaperone proteins, we mapped its interaction with Grp94. Glycosylation of the full-length Grp94 protein was essential for OS-9 binding, although deletion of the Grp94 N-terminal domain relieved this requirement suggesting that the effect was allosteric rather than direct. Although yeast OS-9 is composed of a well-established N-terminal mannose recognition homology lectin domain and a C-terminal dimerization domain, we find that the C-terminal domain of OS-9 in higher eukaryotes contains "mammalian-specific insets" that are specifically recognized by the middle and C-terminal domains of Grp94. Additionally, the Grp94 binding domain in OS-9 was found to be intrinsically disordered. The biochemical analysis of the interacting regions provides insight into the manner by which the two associate and it additionally hints at a plausible biological role for the Grp94/OS-9 complex. PMID:25193139

Seidler, Paul M; Shinsky, Stephen A; Hong, Feng; Li, Zihai; Cosgrove, Michael S; Gewirth, Daniel T

2014-10-23

379

Lectin-like molecules in transcriptome of Littorina littorea hemocytes.  

PubMed

The common periwinkle Littorina littorea was introduced in the list of models for comparative immunobiology as a representative of phylogenetically important taxon Caenogastropoda. Using Illumina sequencing technology, we de novo assembled the transcriptome of Littorina littorea hemocytes from 182 million mRNA-Seq pair-end 100?bp reads into a total of 15,526 contigs clustered in 4472 unigenes. The transcriptome profile was analyzed for presence of carbohydrate-binding molecules in a variety of architectural contexts. Hemocytes' repertoire of lectin-like proteins bearing conserved carbohydrate-recognition domains (CRDs) is highly diversified, including 11 of 15 lectin families earlier described in animals, as well as the novel members of lectin family found for the first time in mollusc species. The new molluscan lineage-specific domain combinations were confirmed by cloning and sequencing, including the fuco-lectin related molecules (FLReMs) composed of N-terminal region with no sequence homology to any known protein, a middle Fucolectin Tachylectin-4 Pentaxrin (FTP) domain, and a C-terminal epidermal growth factor (EGF) repeat region. The repertoire of lectin-like molecules is discussed in terms of their potential participation in the receptor phase of immune response. In total, immune-associated functions may be attributed to 70 transcripts belonging to 6 lectin families. These lectin-like genes show low overlap between species of invertebrates, suggesting relatively rapid evolution of immune-associated genes in the group. The repertoire provides valuable candidates for further characterization of the gene functions in mollusc immunity. PMID:25451301

Gorbushin, Alexander M; Borisova, Elena A

2015-01-01

380

Using lectins to identify hidden antigens in Fasciola hepatica.  

PubMed

Fasciola hepatica is the causative agent of fascioliasis, one of the most economically important helminth diseases of livestock worldwide. Traditionally, fascioliasis has been controlled by the strategic use of fasciolicidal drugs, but the emergence of resistant parasites has spurred an interest in developing vaccines as an alternative means of control. Most vaccine studies to date have evaluated conventional antigens, which are exposed to the host's immune system during the course of a natural infection. 'Hidden' antigens have proven to be effective vaccine candidates in other parasite species, most notably the blood-feeding nematode parasite, Haemonchus contortus, and tend to be expressed in the intestine or gut of the parasite. Fasciola hepatica is known to ingest large quantities of blood and may be vulnerable to this approach. Most, if not all, of the candidate antigens identified thus far have been membrane-bound glycoproteins which were solubilized by detergents. Here, we have attempted to employ lectins to select gut-associated glycoproteins from complex mixtures of somatic extracts of adult F. hepatica. We have conducted a comprehensive lectin-binding screen on adult histological sections with a panel of 16 fluorescently labelled lectins. Seven of the lectins bound to molecules within the gastrodermis but also bound to a range of other tissues. Within the gut tissues, jacalin and peanut lectins bound selectively to the gut lamellae and gastrodermal cells, respectively. These lectins were then used to isolate proteins from the integral membrane protein component of the adult fluke. Both lectins showed selectivity for relatively simple subsets of proteins compared to the original crude extracts. PMID:21208513

McAllister, H C; Nisbet, A J; Skuce, P J; Knox, D P

2011-06-01

381

Isolation of a novel plant lectin with an unusual specificity from Calystegia sepium.  

PubMed

A novel plant lectin has been isolated from the rhizomes of Calystegia sepium (hedge bindweed) and partially characterized. The lectin is a dimeric protein composed of two identical non-covalently linked subunits of 16 kDa. Hapten inhibition studies indicate that the novel lectin is best inhibited by maltose and mannose and hence exhibits a sugar binding specificity that differs in some respects from that of all previously isolated plant lectins. Mitogenicity tests have shown that the Calystegia lectin is a powerful T-cell mitogen. Affinity purification of human, plant and fungal glycoproteins on immobilized C. sepium lectin demonstrates that this novel lectin can be used for the isolation of glycoconjugates from various sources. Moreover, it can be expected that by virtue of its distinct specificity, the new lectin will become an important tool in glycobiology. PMID:9111143

Peumans, W J; Winter, H C; Bemer, V; Van Leuven, F; Goldstein, I J; Truffa-Bachi, P; Van Damme, E J

1997-02-01

382

Mannan Binding Lectin (MBL) genotypes coding for high MBL serum levels are associated with rheumatoid factor negative rheumatoid arthritis in never smokers  

Microsoft Academic Search

Introduction  Previous studies have provided inconsistent results on whether variants in the MBL2 gene, coding for the complement-activating mannan-binding lectin (MBL) protein, associate with rheumatoid arthritis (RA).\\u000a We re-evaluated this in context of the main environmental and genetic risk factors (smoking, HLA-DRB1 'shared epitope' (SE),\\u000a PTPN22*620W), which predispose to rheumatoid factor (RF) and\\/or anti-citrullinated-protein antibody (ACPA)-positive RA.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  In this population-based EIRA

Saedis Saevarsdottir; Bo Ding; Kristjan Steinsson; Gerdur Grondal; Helgi Valdimarsson; Lars Alfredsson; Lars Klareskog; Leonid Padyukov

2011-01-01

383

Quantitation of two endogenous lactose-inhibitable lectins in embryonic and adult chicken tissues  

Microsoft Academic Search

Two lactose-binding lectins from chicken tissues, chicken-lactose-lectin-I (CLL-I) and chicken-lactose-lectin-II (CLL-II) were quantified with a radioimmunoassay in extracts of a number of developing and adult chicken tissues. Both lectins could be measured in the same extract without separation, because they showed no significant immunological cross- reactivity. Many embryonic and adult tissues, including brain, heart, intestine, kidney, liver, lung, muscle, pancreas,

ERIC C. BEYER; SAMUEL H. BARONDES

1982-01-01

384

Isolation and Characterization of Lectins from Rhizoctonia crocorum and Athelia rolfsii  

Microsoft Academic Search

Two new lectins were isolated from mycelium of Rhizoctonia crocorum and Athelia rorfsii by affinity chromatography on mucin-Sepharose. The Rhizoctonia crocorum lectin (RCL) was a tetramer of 11 kDa subunits whereas the Athelia rolfii lectin (ARL) was a dimer of two 17 kDa subunits. Both lectins were rich in asparagine\\/aspartic acid, glutamine\\/glutamic acid, glycine, lysine and serine. In contrast to

JAN T. C. KELLENS; ANTHONY K. ALLEN; WILLY J. PEUMANS

1989-01-01

385

Purification and some properties of a lectin from the fruit juice of the tomato (Lycopersicon esculentum).  

PubMed

In the tomato (Lycopersicon esculentum) plant, the fruit juice was found to be the richest source of agglutinating activity. The lectin responsible could be inhibited by oligomers of N-acetylglucosamine, and this property was exploited to purify the lectin by affinity adsorption on trypsin-treated erythrocytes. The lectin is a glycoprotein that cross-reacts immunologically with the lectin from Datura stramonium (thorn-apple). PMID:7378052

Kilpatrick, D C

1980-01-01

386

Evolution of the complement system in protostomes revealed by de novo transcriptome analysis of six species of Arthropoda.  

PubMed

To elucidate the evolutionary history of the complement system in Arthropoda, de novo transcriptome analysis was performed with six species among the Chelicerata, Myriapoda, and Crustacea, and complement genes were identified based on their characteristic domain structures.