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Sample records for activation regulates microglial

  1. Microglial P2Y12 receptors regulate microglial activation and surveillance during neuropathic pain.

    PubMed

    Gu, Nan; Eyo, Ukpong B; Murugan, Madhuvika; Peng, Jiyun; Matta, Sanjana; Dong, Hailong; Wu, Long-Jun

    2016-07-01

    Microglial cells are critical in the pathogenesis of neuropathic pain and several microglial receptors have been proposed to mediate this process. Of these receptors, the P2Y12 receptor is a unique purinergic receptor that is exclusively expressed by microglia in the central nervous system (CNS). In this study, we set forth to investigate the role of P2Y12 receptors in microglial electrophysiological and morphological (static and dynamic) activation during spinal nerve transection (SNT)-induced neuropathic pain in mice. First, we found that a genetic deficiency of the P2Y12 receptor (P2Y12(-/-) mice) ameliorated pain hypersensitivities during the initiation phase of neuropathic pain. Next, we characterised both the electrophysiological and morphological properties of microglia in the superficial spinal cord dorsal horn following SNT injury. We show dramatic alterations including a peak at 3days post injury in microglial electrophysiology while high resolution two-photon imaging revealed significant changes of both static and dynamic microglial morphological properties by 7days post injury. Finally, in P2Y12(-/-) mice, these electrophysiological and morphological changes were ameliorated suggesting roles for P2Y12 receptors in SNT-induced microglial activation. Our results therefore indicate that P2Y12 receptors regulate microglial electrophysiological as well as static and dynamic microglial properties after peripheral nerve injury, suggesting that the microglial P2Y12 receptor could be a potential therapeutic target for the treatment of neuropathic pain. PMID:26576724

  2. Microglial Activation & Chronic Neurodegeneration

    PubMed Central

    Lull, Melinda E.; Block, Michelle L.

    2010-01-01

    Microglia, the resident innate immune cells in the brain, have long been implicated in the pathology of neurodegenerative diseases. Accumulating evidence points to activated microglia as a chronic source of multiple neurotoxic factors, including TNFα, NO, IL1-β, and reactive oxygen species (ROS), driving progressive neuron damage. Microglia can become chronically activated by either a single stimulus (ex. LPS or neuron damage) or multiple stimuli exposures to result in cumulative neuronal loss over time. While the mechanisms driving these phenomena are just beginning to be understood, reactive microgliosis (the microglial response to neuron damage) and ROS have been implicated as key mechanisms of chronic and neurotoxic microglial activation, particularly in the case of Parkinson’s Disease. Here, we review the mechanisms of neurotoxicity associated with chronic microglial activation and discuss the role of neuronal death and microglial ROS driving the chronic and toxic microglial phenotype. PMID:20880500

  3. Isoflurane preconditioning provides neuroprotection against stroke by regulating the expression of the TLR4 signalling pathway to alleviate microglial activation

    PubMed Central

    Sun, Meiyan; Deng, Bin; Zhao, Xiaoyong; Gao, Changjun; Yang, Lu; Zhao, Hui; Yu, Daihua; Zhang, Feng; Xu, Lixian; Chen, Lei; Sun, Xude

    2015-01-01

    Excessive microglial activation often contributes to inflammation-mediated neurotoxicity in the ischemic penumbra during the acute stage of ischemic stroke. Toll-like receptor 4 (TLR4) has been reported to induce microglial activation via the NF-κB pathway. Isoflurane preconditioning (IP) can provide neuroprotection and inhibit microglial activation. In this study, we investigated the roles of the TLR4 signalling pathway in IP to exert neuroprotection following ischemic stroke in vivo and in vitro. The results showed that 2% IP alleviated neurological deficits, reduced the infarct volume, attenuated apoptosis and weakened microglial activation in the ischemic penumbra. Furthermore, IP down-regulated the expression of HSP 60, TLR4 and MyD88 and up-regulated inhibitor of IκB-α expression compared with I/R group in vivo. In vitro, 2% IP and a specific inhibitor of TLR4, CLI-095, down-regulated the expression of TLR4, MyD88, IL-1β, TNF-α and Bax, and up-regulated IκB-α and Bcl-2 expression compared with OGD group. Moreover, IP and CLI-095 attenuated microglial activation-induced neuronal apoptosis, and overexpression of the TLR4 gene reversed the neuroprotective effects of IP. In conclusion, IP provided neuroprotection by regulating TLR4 expression directly, alleviating microglial activation and neuroinflammation. Thus, inhibiting the activation of microglial activation via TLR4 may be a new avenue for stroke treatment. PMID:26086415

  4. Regulation of rotenone-induced microglial activation by 5-lipoxygenase and cysteinyl leukotriene receptor 1.

    PubMed

    Zhang, Xiao-Yan; Chen, Lu; Yang, Yi; Xu, Dong-Min; Zhang, Si-Ran; Li, Chen-Tan; Zheng, Wei; Yu, Shu-Ying; Wei, Er-Qing; Zhang, Li-Hui

    2014-07-14

    The 5-lipoxygenase (5-LOX) products cysteinyl leukotrienes (CysLTs) are potent pro-inflammatory mediators. CysLTs mediate their biological actions through activating CysLT receptors (CysLT(1)R and CysLT(2)R). We have recently reported that 5-LOX and CysLT(1)R mediated PC12 cell injury induced by high concentrations of rotenone (0.3-10 μM), which was reduced by the selective 5-LOX inhibitor zileuton and CysLT(1)R antagonist montelukast. The purpose of this study was to examine the regulatory roles of the 5-LOX/CysLT(1)R pathway in microglial activation induced by low concentration rotenone. After mouse microglial BV2 cells were stimulated with rotenone (0.3-3 nM), phagocytosis and release of pro-inflammatory cytokine were assayed as indicators of microglial activation. We found that rotenone (1 and 3 nM) increased BV2 microglial phagocytosis and the release of the pro-inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Zileuton and montelukast prevented rotenone (3 nM)-induced phagocytosis and cytokine release. Furthermore, rotenone significantly up-regulated 5-LOX expression, induced 5-LOX translocation to the nuclear envelope, and increased the production of CysLTs. These responses were inhibited by zileuton. Rotenone also increased CysLT(1)R expression and induced nuclear translocation of CysLT(1)R. In primary rat microglia, rotenone (10 nM) increased release of IL-1β and TNF-α, whereas zileuton (0.1 μΜ) and montelukast (0.01 μΜ) significantly inhibited this response. These results indicated that 5-LOX and CysLT(1)R might be key regulators of microglial activation induced by low concentration of rotenone. Interference of 5-LOX/CysLT(1)R pathway may be an effective therapeutic strategy for microglial inflammation. PMID:24858057

  5. TREM2 regulates microglial cell activation in response to demyelination in vivo

    PubMed Central

    Cantoni, Claudia; Bollman, Bryan; Licastro, Danilo; Xie, Mingqiang; Mikesell, Robert; Schmidt, Robert; Yuede, Carla M.; Galimberti, Daniela; Olivecrona, Gunilla; Klein, Robyn S.; Cross, Anne H.; Otero, Karel; Piccio, Laura

    2015-01-01

    Microglia are phagocytic cells that survey the brain and perform neuroprotective functions in response to tissue damage, but their activating receptors are largely unknown. Triggering receptor expressed on myeloid cells 2 (TREM2) is a microglial immunoreceptor whose loss-of-function mutations in humans cause presenile dementia, while genetic variants are associated with increased risk of neurodegenerative diseases. In myeloid cells, TREM2 has been involved in the regulation of phagocytosis, cell proliferation and inflammatory responses in vitro. However, it is unknown how TREM2 contributes to microglia function in vivo. Here, we identify a critical role for TREM2 in the activation and function of microglia during cuprizone (CPZ)-induced demyelination. TREM2-deficient (TREM2−/−) mice had defective clearance of myelin debris and more axonal pathology, resulting in impaired clinical performances compared to wild-type (WT) mice. TREM2−/− microglia proliferated less in areas of demyelination and were less activated, displaying a more resting morphology and decreased expression of the activation markers MHC II and inducible nitric oxide synthase as compared to WT. Mechanistically, gene expression and ultrastructural analysis of microglia suggested a defect in myelin degradation and phagosome processing during CPZ intoxication in TREM2−/− microglia. These findings place TREM2 as a key regulator of microglia activation in vivo in response to tissue damage. PMID:25631124

  6. Molecular mechanisms of microglial activation.

    PubMed

    Zielasek, J; Hartung, H P

    1996-01-01

    Microglial cells are brain macrophages which serve specific functions in the defense of the central nervous system (CNS) against microorganisms, the removal of tissue debris in neurodegenerative diseases or during normal development, and in autoimmune inflammatory disorders of the brain. In cultured microglial cells, several soluble inflammatory mediators such as cytokines and bacterial products like lipopolysaccharide (LPS) were demonstrated to induce a wide range of microglial activities, e.g. increased phagocytosis, chemotaxis, secretion of cytokines, activation of the respiratory burst and induction of nitric oxide synthase. Since heightened microglial activation was shown to play a role in the pathogenesis of experimental inflammatory CNS disorders, understanding the molecular mechanisms of microglial activation may lead to new treatment strategies for neurodegenerative disorders, multiple sclerosis and bacterial or viral infections of the nervous system. PMID:8876774

  7. Hippocampal microglial activation and glucocorticoid receptor down-regulation precipitate visceral hypersensitivity induced by colorectal distension in rats.

    PubMed

    Zhang, Gongliang; Zhao, Bing-Xue; Hua, Rong; Kang, Jie; Shao, Bo-Ming; Carbonaro, Theresa M; Zhang, Yong-Mei

    2016-03-01

    Visceral hypersensitivity is a common characteristic in patients suffering from irritable bowel syndrome (IBS) and other disorders with visceral pain. Although the pathogenesis of visceral hypersensitivity remains speculative due to the absence of pathological changes, the long-lasting sensitization in neuronal circuitry induced by early life stress may play a critical role beyond the digestive system even after complete resolution of the initiating event. The hippocampus integrates multiple sources of afferent inputs and sculpts integrated autonomic outputs for pain and analgesia regulation. Here, we examined the hippocampal mechanism in the pathogenesis of visceral hypersensitivity with a rat model induced by neonatal and adult colorectal distensions (CRDs). Neither neonatal nor adult CRD evoked behavioral abnormalities in adulthood; however, adult re-exposure to CRD induced persistent visceral hypersensitivity, depression-like behaviors, and spatial learning impairment in rats that experienced neonatal CRD. Rats that experienced neonatal and adult CRDs presented a decrease in hippocampal glucocorticoid receptor (GR) immunofluorescence staining and protein expression, and increases in hippocampal microglial activation and cytokine (IL-1β and TNF-α) accumulation. The decrease in hippocampal GR expression and increase in hippocampal IL-1β and TNF-α accumulation could be prevented by hippocampal local infusion of minocycline, a microglial inhibitor. These results suggest that neonatal CRD can increase the vulnerability of hippocampal microglia, and adult CRD challenge facilitates the hippocampal cytokine release from the sensitized microglia, which down-regulates hippocampal GR protein expression and, subsequently, precipitates visceral hypersensitivity. PMID:26656865

  8. Systemic inflammation regulates microglial responses to tissue damage in vivo.

    PubMed

    Gyoneva, Stefka; Davalos, Dimitrios; Biswas, Dipankar; Swanger, Sharon A; Garnier-Amblard, Ethel; Loth, Francis; Akassoglou, Katerina; Traynelis, Stephen F

    2014-08-01

    Microglia, the resident immune cells of the central nervous system, exist in either a "resting" state associated with physiological tissue surveillance or an "activated" state in neuroinflammation. We recently showed that ATP is the primary chemoattractor to tissue damage in vivo and elicits opposite effects on the motility of activated microglia in vitro through activation of adenosine A2A receptors. However, whether systemic inflammation affects microglial responses to tissue damage in vivo remains largely unknown. Using in vivo two-photon imaging of mice, we show that injection of lipopolysaccharide (LPS) at levels that can produce both clear neuroinflammation and some features of sepsis significantly reduced the rate of microglial response to laser-induced ablation injury in vivo. Under proinflammatory conditions, microglial processes initially retracted from the ablation site, but subsequently moved toward and engulfed the damaged area. Analyzing the process dynamics in 3D cultures of primary microglia indicated that only A2A , but not A1 or A3 receptors, mediate process retraction in LPS-activated microglia. The A2A receptor antagonists caffeine and preladenant reduced adenosine-mediated process retraction in activated microglia in vitro. Finally, administration of preladenant before induction of laser ablation in vivo accelerated the microglial response to injury following systemic inflammation. The regulation of rapid microglial responses to sites of injury by A2A receptors could have implications for their ability to respond to the neuronal death occurring under conditions of neuroinflammation in neurodegenerative disorders. PMID:24807189

  9. Microglial phagocytosis and activation underlying photoreceptor degeneration is regulated by CX3CL1-CX3CR1 signaling in a mouse model of retinitis pigmentosa.

    PubMed

    Zabel, Matthew K; Zhao, Lian; Zhang, Yikui; Gonzalez, Shaimar R; Ma, Wenxin; Wang, Xu; Fariss, Robert N; Wong, Wai T

    2016-09-01

    Retinitis pigmentosa (RP), a disease characterized by the progressive degeneration of mutation-bearing photoreceptors, is a significant cause of incurable blindness in the young worldwide. Recent studies have found that activated retinal microglia contribute to photoreceptor demise via phagocytosis and proinflammatory factor production, however mechanisms regulating these contributions are not well-defined. In this study, we investigate the role of CX3CR1, a microglia-specific receptor, in regulating microglia-mediated degeneration using the well-established rd10 mouse model of RP. We found that in CX3CR1-deficient (CX3CR1(GFP/GFP) ) rd10 mice microglial infiltration into the photoreceptor layer was significantly augmented and associated with accelerated photoreceptor apoptosis and atrophy compared with CX3CR1-sufficient (CX3CR1(GFP/+) ) rd10 littermates. CX3CR1-deficient microglia demonstrated increased phagocytosis as evidenced by (1) having increased numbers of phagosomes in vivo, (2) an increased rate of phagocytosis of fluorescent beads and photoreceptor cellular debris in vitro, and (3) increased photoreceptor phagocytosis dynamics on live cell imaging in retinal explants, indicating that CX3CR1 signaling in microglia regulates the phagocytic clearance of at-risk photoreceptors. We also found that CX3CR1 deficiency in retinal microglia was associated with increased expression of inflammatory cytokines and microglial activation markers. Significantly, increasing CX3CL1-CX3CR1 signaling in the rd10 retina via exogenous intravitreal delivery of recombinant CX3CL1 was effective in (1) decreasing microglial infiltration, phagocytosis and activation, and (2) improving structural and functional features of photoreceptor degeneration. These results indicate that CX3CL1-CX3CR1 signaling is a molecular mechanism capable of modulating microglial-mediated degeneration and represents a potential molecular target in therapeutic approaches to RP. GLIA 2016

  10. Phlorofucofuroeckol B suppresses inflammatory responses by down-regulating nuclear factor κB activation via Akt, ERK, and JNK in LPS-stimulated microglial cells.

    PubMed

    Yu, Dong-Kyung; Lee, Bonggi; Kwon, Misung; Yoon, Nayoung; Shin, Taisun; Kim, Nam-Gil; Choi, Jae-Sue; Kim, Hyeung-Rak

    2015-10-01

    Microglial activation has been implicated in many neurological disorders for its inflammatory and neurotrophic effects. In this study, we investigated the effects of phlorofucofuroeckol B (PFF-B) isolated from Ecklonia stolonifera, on the production of inflammatory mediators in lipopolysaccharide (LPS)-stimulated microglia. PFF-B decreased secretion of pro-inflammatory cytokines including tumor necrosis factor α, interleukin (IL)-1β, and IL-6 and the expression of pro-inflammatory proteins such as cyclooxygenase-2 and inducible nitric oxide synthase in LPS-stimulated BV-2 cells. Profoundly, PFF-B inhibited activation of nuclear factor kappaB (NF-κB) by preventing the degradation of inhibitor κB-α (IκB-α), which led to prevent the nuclear translocation of p65 NF-κB subunit. Moreover, PFF-B inhibited the phosphorylation of Akt, ERK, and JNK. These results indicate that the anti-inflammatory effect of PFF-B on LPS-stimulated microglial cells is mainly regulated by the inhibition of IκB-α/NF-κB and Akt/ERK/JNK pathways. Our study suggests that PFF-B can be considered as a therapeutic agent against neuroinflammation by inhibiting microglial activation. PMID:26341413

  11. Endocannabinoids regulate the activity of astrocytic hemichannels and the microglial response against an injury: In vivo studies.

    PubMed

    Vázquez, Carmen; Tolón, Rosa María; Pazos, María Ruth; Moreno, Marta; Koester, Erin C; Cravatt, Benjamin F; Hillard, Cecilia J; Romero, Julián

    2015-07-01

    Anandamide (AEA) is an endocannabinoid (EC) that modulates multiple functions in the CNS and that is released in areas of injury, exerting putative neuroprotective actions. In the present study, we have used intravital microscopy to analyze the role of the EC system in the glial response against an acute insult. Our data show that AEA modulates astroglial function in vivo by increasing connexin-43 hemichannel (HC) activity. Furthermore, the genetic inactivation of the AEA-degrading enzyme, fatty acid amide hydrolase (FAAH), also increased HC activity and enhanced the microglial response against an acute injury to the brain parenchyma, effects that were mediated by cannabinoid CB1 receptors. The contribution of ATP released through an astrocytic HC was critical for the microglial response, as this was prevented by the use of the HC blocker flufenamic acid and by apyrase. As could be expected, brain concentrations of AEA, palmitoylethanolamide (PEA) and oleoylethanolamide (OEA) were elevated in FAAH-null mice, while 2-arachidonoylglycerol (2-AG) concentrations remained unaltered. In summary, these findings demonstrate that AEA modifies glial functions by promoting an enhanced pro-inflammatory glial response in the brain. PMID:25917763

  12. Biomarkers for Microglial Activation in Alzheimer's Disease

    PubMed Central

    Lautner, Ronald; Mattsson, Niklas; Schöll, Michael; Augutis, Kristin; Blennow, Kaj; Olsson, Bob; Zetterberg, Henrik

    2011-01-01

    Intensive research over the last decades has provided increasing evidence for neuroinflammation as an integral part in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease (AD). Inflammatory responses in the central nervous system (CNS) are initiated by activated microglia, representing the first line of the innate immune defence of the brain. Therefore, biochemical markers of microglial activation may help us understand the underlying mechanisms of neuroinflammation in AD as well as the double-sided qualities of microglia, namely, neuroprotection and neurotoxicity. In this paper we summarize candidate biomarkers of microglial activation in AD along with a survey of recent neuroimaging techniques. PMID:22114747

  13. Transduced PEP-1-PON1 proteins regulate microglial activation and dopaminergic neuronal death in a Parkinson's disease model.

    PubMed

    Kim, Mi Jin; Park, Meeyoung; Kim, Dae Won; Shin, Min Jea; Son, Ora; Jo, Hyo Sang; Yeo, Hyeon Ji; Cho, Su Bin; Park, Jung Hwan; Lee, Chi Hern; Kim, Duk-Soo; Kwon, Oh-Shin; Kim, Joon; Han, Kyu Hyung; Park, Jinseu; Eum, Won Sik; Choi, Soo Young

    2015-09-01

    Parkinson's disease (PD) is an oxidative stress-mediated neurodegenerative disorder caused by selective dopaminergic neuronal death in the midbrain substantia nigra. Paraoxonase 1 (PON1) is a potent inhibitor of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) against oxidation by destroying biologically active phospholipids with potential protective effects against oxidative stress-induced inflammatory disorders. In a previous study, we constructed protein transduction domain (PTD) fusion PEP-1-PON1 protein to transduce PON1 into cells and tissue. In this study, we examined the role of transduced PEP-1-PON1 protein in repressing oxidative stress-mediated inflammatory response in microglial BV2 cells after exposure to lipopolysaccharide (LPS). Moreover, we identified the functions of transduced PEP-1-PON1 proteins which include, mitigating mitochondrial damage, decreasing reactive oxidative species (ROS) production, matrix metalloproteinase-9 (MMP-9) expression and protecting against 1-methyl-4-phenylpyridinium (MPP(+))-induced neurotoxicity in SH-SY5Y cells. Furthermore, transduced PEP-1-PON1 protein reduced MMP-9 expression and protected against dopaminergic neuronal cell death in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice model. Taken together, these results suggest a promising therapeutic application of PEP-1-PON1 proteins against PD and other inflammation and oxidative stress-related neuronal diseases. PMID:26117230

  14. Estrogen ameliorates microglial activation by inhibiting the Kir2.1 inward-rectifier K(+) channel.

    PubMed

    Wu, Shih-Ying; Chen, Yun-Wen; Tsai, Sheng-Feng; Wu, Sheng-Nan; Shih, Yao-Hsiang; Jiang-Shieh, Ya-Fen; Yang, Ting-Ting; Kuo, Yu-Min

    2016-01-01

    Microglial activation is implicated in the pathogenesis of Parkinson's disease (PD). Although the etiology of PD remains unclear, age and male gender are known PD risk factors. By comparing microglia and dopaminergic (DA) neurons in the substantia nigra (SN) of male and female mice of different ages, we found that the degrees of microglial activation and DA neuron loss increased with age in both genders, but were more pronounced in males, as were peripheral lipopolysaccharide (LPS)-induced microglial activation and DA neuron loss. A bilateral ovariectomy (OVX) eliminated the female-associated protection against age- and LPS-induced microglial activation, which suggests that ovary hormones are involved in gender-specific responses. Treating female mice with 17β-estradiol supplements reduced the age-associated microglial activation in OVX mice. Moreover, pretreating mouse BV2 microglial cells with 17β-estradiol inhibited LPS-induced elevation of Toll-like receptor 4, phosphorylated p38, and TNF-α levels. We then examined the effect of 17β-estradiol on inward-rectifier K(+) channel Kir2.1, a known regulator of microglial activation. We found that 17β-estradiol inhibited the Kir2.1 activity of BV2 cells by reducing the probability that the channel would be open. We conclude that age- and inflammation-associated microglial activation is attenuated by ovarian estrogen, because it inhibits Kir2.1. PMID:26960267

  15. Estrogen ameliorates microglial activation by inhibiting the Kir2.1 inward-rectifier K+ channel

    PubMed Central

    Wu, Shih-Ying; Chen, Yun-Wen; Tsai, Sheng-Feng; Wu, Sheng-Nan; Shih, Yao-Hsiang; Jiang-Shieh, Ya-Fen; Yang, Ting-Ting; Kuo, Yu-Min

    2016-01-01

    Microglial activation is implicated in the pathogenesis of Parkinson’s disease (PD). Although the etiology of PD remains unclear, age and male gender are known PD risk factors. By comparing microglia and dopaminergic (DA) neurons in the substantia nigra (SN) of male and female mice of different ages, we found that the degrees of microglial activation and DA neuron loss increased with age in both genders, but were more pronounced in males, as were peripheral lipopolysaccharide (LPS)-induced microglial activation and DA neuron loss. A bilateral ovariectomy (OVX) eliminated the female-associated protection against age- and LPS-induced microglial activation, which suggests that ovary hormones are involved in gender-specific responses. Treating female mice with 17β-estradiol supplements reduced the age-associated microglial activation in OVX mice. Moreover, pretreating mouse BV2 microglial cells with 17β-estradiol inhibited LPS-induced elevation of Toll-like receptor 4, phosphorylated p38, and TNF-α levels. We then examined the effect of 17β-estradiol on inward-rectifier K+ channel Kir2.1, a known regulator of microglial activation. We found that 17β-estradiol inhibited the Kir2.1 activity of BV2 cells by reducing the probability that the channel would be open. We conclude that age- and inflammation-associated microglial activation is attenuated by ovarian estrogen, because it inhibits Kir2.1. PMID:26960267

  16. TAM receptors regulate multiple features of microglial physiology.

    PubMed

    Fourgeaud, Lawrence; Través, Paqui G; Tufail, Yusuf; Leal-Bailey, Humberto; Lew, Erin D; Burrola, Patrick G; Callaway, Perri; Zagórska, Anna; Rothlin, Carla V; Nimmerjahn, Axel; Lemke, Greg

    2016-04-14

    Microglia are damage sensors for the central nervous system (CNS), and the phagocytes responsible for routine non-inflammatory clearance of dead brain cells. Here we show that the TAM receptor tyrosine kinases Mer and Axl regulate these microglial functions. We find that adult mice deficient in microglial Mer and Axl exhibit a marked accumulation of apoptotic cells specifically in neurogenic regions of the CNS, and that microglial phagocytosis of the apoptotic cells generated during adult neurogenesis is normally driven by both TAM receptor ligands Gas6 and protein S. Using live two-photon imaging, we demonstrate that the microglial response to brain damage is also TAM-regulated, as TAM-deficient microglia display reduced process motility and delayed convergence to sites of injury. Finally, we show that microglial expression of Axl is prominently upregulated in the inflammatory environment that develops in a mouse model of Parkinson's disease. Together, these results establish TAM receptors as both controllers of microglial physiology and potential targets for therapeutic intervention in CNS disease. PMID:27049947

  17. Trimethyltin-Induced Microglial Activation via NADPH Oxidase and MAPKs Pathway in BV-2 Microglial Cells

    PubMed Central

    Kim, Da Jung; Kim, Yong Sik

    2015-01-01

    Trimethyltin (TMT) is known as a potent neurotoxicant that causes neuronal cell death and neuroinflammation, particularly in the hippocampus. Microglial activation is one of the prominent pathological features of TMT neurotoxicity. Nevertheless, it remains unclear how microglial activation occurs in TMT intoxication. In this study, we aimed to investigate the signaling pathways in TMT-induced microglial activation using BV-2 murine microglial cells. Our results revealed that TMT generates reactive oxygen species (ROS) and increases the expression of CD11b and nuclear factor-κB- (NF-κB-) mediated nitric oxide (NO) and tumor necrosis factor- (TNF-) α in BV-2 cells. We also observed that NF-κB activation was controlled by p38 and JNK phosphorylation. Moreover, TMT-induced ROS generation occurred via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in BV-2 cells. Interestingly, treatment with the NADPH oxidase inhibitor apocynin significantly suppressed p38 and JNK phosphorylation and NF-κB activation and ultimately the production of proinflammatory mediators upon TMT exposure. These findings indicate that NADPH oxidase-dependent ROS generation activated p38 and JNK mitogen-activated protein kinases (MAPKs), which then stimulated NF-κB to release proinflammatory mediators in the TMT-treated BV-2 cells. PMID:26221064

  18. Regulation of Tau Pathology by the Microglial Fractalkine Receptor

    PubMed Central

    Bhaskar, Kiran; Konerth, Megan; Kokiko-Cochran, Olga N.; Cardona, Astrid; Ransohoff, Richard M.; Lamb, Bruce T.

    2010-01-01

    SUMMARY Aggregates of the hyperphosphorylated microtubule associated protein tau (MAPT) are an invariant neuropathological feature of tauopathies. Here we show that microglial neuroinflammation promotes MAPT phosphorylation and aggregation. First, lipopolysaccharide-induced microglial activation promotes hyperphosphorylation of endogenous mouse MAPT in non-transgenic mice that is further enhanced in mice lacking the microglial-specific fractalkine receptor (CX3CR1) and is dependent upon functional toll-like receptor 4 and interleukin 1 (IL1) receptors. Second, humanized MAPT transgenic mice lacking CX3CR1 exhibited enhanced MAPT phosphorylation and aggregation as well as behavioral impairments that correlated with increased levels of active p38 MAPK. Third, in vitro experiments demonstrate that microglial activation elevates the level of active p38 MAPK and enhances MAPT hyperphosphorylation within neurons that can be blocked by administration of an interleukin 1 receptor antagonist and a specific p38 MAPK inhibitor. Taken together, our results suggest that CX3CR1 and IL1/p38 MAPK may serve as novel therapeutic targets for human tauopathies. PMID:20920788

  19. Fractalkine Attenuates Microglial Cell Activation Induced by Prenatal Stress

    PubMed Central

    Ślusarczyk, Joanna; Trojan, Ewa; Głombik, Katarzyna; Chamera, Katarzyna; Roman, Adam; Budziszewska, Bogusława; Basta-Kaim, Agnieszka

    2016-01-01

    The potential contribution of inflammation to the development of neuropsychiatric diseases has recently received substantial attention. In the brain, the main immune cells are the microglia. As they are the main source of inflammatory factors, it is plausible that the regulation of their activation may be a potential therapeutic target. Fractalkine (CX3CL1) and its receptor CX3CR1 play a crucial role in the control of the biological activity of the microglia. In the present study, using microglial cultures we investigated whether fractalkine is able to reverse changes in microglia caused by a prenatal stress procedure. Our study found that the microglia do not express fractalkine. Prenatal stress decreases the expression of the fractalkine receptor, which in turn is enhanced by the administration of exogenous fractalkine. Moreover, treatment with fractalkine diminishes the prenatal stress-induced overproduction of proinflammatory factors such as IL-1β, IL-18, IL-6, TNF-α, CCL2, or NO in the microglial cells derived from prenatally stressed newborns. In conclusion, the present results revealed that the pathological activation of microglia in prenatally stressed newborns may be attenuated by fractalkine administration. Therefore, understanding of the role of the CX3CL1-CX3CR1 system may help to elucidate the mechanisms underlying the neuron-microglia interaction and its role in pathological conditions in the brain. PMID:27239349

  20. Peripheral viral infection induced microglial sensome genes and enhanced microglial cell activity in the hippocampus of neonatal piglets.

    PubMed

    Ji, Peng; Schachtschneider, Kyle M; Schook, Lawrence B; Walker, Frederick R; Johnson, Rodney W

    2016-05-01

    Although poorly understood, early-life infection is predicted to affect brain microglial cells, making them hypersensitive to subsequent stimuli. To investigate this, we assessed gene expression in hippocampal tissue obtained from a previously published study reporting increased microglial cell activity and reduced hippocampal-dependent learning in neonatal piglets infected with porcine reproductive and respiratory syndrome virus (PRRSV), a virus that induces interstitial pneumonia. Infection altered expression of 455 genes, of which 334 were up-regulated and 121 were down-regulated. Functional annotation revealed that immune function genes were enriched among the up-regulated differentially expressed genes (DEGs), whereas calcium binding and synaptic vesicle genes were enriched among the down-regulated DEGs. Twenty-six genes encoding part of the microglia sensory apparatus (i.e., the sensome) were up-regulated (e.g., IL1R1, TLR2, and TLR4), whereas 15 genes associated with the synaptosome and synaptic receptors (e.g., NPTX2, GABRA2, and SLC5A7) were down-regulated. As the sensome may foretell microglia reactivity, we next inoculated piglets with culture medium or PRRSV at PD 7 and assessed hippocampal microglia morphology and function at PD 28 when signs of infection were waning. Consistent with amplification of the sensome, microglia from PRRSV piglets had enhanced responsiveness to chemoattractants, increased phagocytic activity, and secreted more TNFα in response to lipopolysaccharide and Poly I:C. Immunohistochemical staining indicated PRRSV infection increased microglia soma length and length-to-width ratio. Bipolar rod-like microglia not evident in hippocampus of control piglets, were present in infected piglets. Collectively, this study suggests early-life infection alters the microglia sensome as well as microglial cell morphology and function. PMID:26872419

  1. Nitrated Alpha Synuclein Induced Alterations in Microglial Immunity is Regulated by CD4+ T Cell Subsets1

    PubMed Central

    Reynolds, Ashley D.; Stone, David K.; Mosley, R. Lee; Gendelman, Howard E.

    2009-01-01

    Microglial inflammatory neuroregulatory activities affect the tempo of nigrostriatal degeneration during Parkinson's disease (PD). Such activities are induced, in part, by misfolded, nitrated alpha-synuclein (N-α-syn) within Lewy bodies released from dying or dead dopaminergic neurons. Such pathobiologic events initiate innate and adaptive immune responses affecting neurodegeneration. We posit that the neurobiological activities of activated microglia are affected by cell-protein and cell-cell contacts, in that microglial interactions with N-α-syn and CD4+ T cells substantively alter the microglial proteome. This leads to alterations in cell homeostatic functions and disease. CD4+CD25+ regulatory T cells (Treg) suppress N-α-syn microglial induced reactive oxygen species and nuclear factor kappa B activation by modulating redox-active enzymes, cell migration, phagocytosis, and bioenergetic protein expression and cell function. In contrast, CD4+CD25− effector T cells exacerbate microglial inflammation and induce “putative” neurotoxic responses. These data support the importance of adaptive immunity in the regulation of PD-associated microglial inflammation. PMID:19299711

  2. Tiagabine Protects Dopaminergic Neurons against Neurotoxins by Inhibiting Microglial Activation

    PubMed Central

    Liu, Jie; Huang, Dongping; Xu, Jing; Tong, Jiabin; Wang, Zishan; Huang, Li; Yang, Yufang; Bai, Xiaochen; Wang, Pan; Suo, Haiyun; Ma, Yuanyuan; Yu, Mei; Fei, Jian; Huang, Fang

    2015-01-01

    Microglial activation and inflammation are associated with progressive neuronal apoptosis in neurodegenerative disorders such as Parkinson’s disease (PD). γ-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system, has recently been shown to play an inhibitory role in the immune system. Tiagabine, a piperidine derivative, enhances GABAergic transmission by inhibiting GABA transporter 1 (GAT 1). In the present study, we found that tiagabine pretreatment attenuated microglial activation, provided partial protection to the nigrostriatal axis and improved motor deficits in a methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. The protective function of tiagabine was abolished in GAT 1 knockout mice that were challenged with MPTP. In an alternative PD model, induced by intranigral infusion of lipopolysaccharide (LPS), microglial suppression and subsequent neuroprotective effects of tiagabine were demonstrated. Furthermore, the LPS-induced inflammatory activation of BV-2 microglial cells and the toxicity of conditioned medium toward SH-SY5Y cells were inhibited by pretreatment with GABAergic drugs. The attenuation of the nuclear translocation of nuclear factor κB (NF-κB) and the inhibition of the generation of inflammatory mediators were the underlying mechanisms. Our results suggest that tiagabine acts as a brake for nigrostriatal microglial activation and that it might be a novel therapeutic approach for PD. PMID:26499517

  3. Microglial activation mediates host neuronal survival induced by neural stem cells.

    PubMed

    Wu, Hui-Mei; Zhang, Li-Feng; Ding, Pei-Shang; Liu, Ya-Jing; Wu, Xu; Zhou, Jiang-Ning

    2014-07-01

    The rational of neural stem cells (NSCs) in the therapy of neurological disease is either to replace dead neurons or to improve host neuronal survival, the latter of which has got less attention and the underlying mechanism is as yet little known. Using a transwell co-culture system, we reported that, in organotypic brain slice cultures, NSCs significantly improved host neuronal viability. Interestingly, this beneficial effect of NSCs was abrogated by a microglial inhibitor minocycline, while it was mimicked by a microglial agonist, Toll-like receptor 9 (TLR9) ligand CpG-ODN, which supports the pro-vital mediation by microglia on this NSCs-improved neuronal survival. Moreover, we showed that NSCs significantly induced host microglial movement and higher expression of a microglial marker IBA-1, the latter of which was positively correlated with TLR9 or extracellular-regulated protein kinases 1/2 (ERK1/2) activation. Real-time PCR revealed that NSCs inhibited the expression of pro-inflammatory molecules, but significantly increased the expression of molecules associated with a neuroprotective phenotype such as CX3CR1, triggering receptor expressed on myeloid cells-2 (TREM2) and insulin growth factor 1 (IGF-1). Similarly, in the microglia cells, NSCs induced the same microglial response as that in the slices. Further treatment with TLR9 ligand CpG-ODN, TLR9 inhibitor chloroquine (CQ) or ERK1/2 inhibitor U0126 demonstrated that TLR9-ERK1/2 pathway was involved in the NSCs-induced microglial activation. Collectively, this study indicated that NSCs improve host neuronal survival by switching microglia from a detrimental to a neuroprotective phenotype in adult mouse brain, and the microglial TLR9-ERK1/2 pathway seems to participate in this NSCs-mediated rescue action. PMID:24725889

  4. Role of Microglial Activation in the Pathophysiology of Bacterial Meningitis.

    PubMed

    Barichello, Tatiana; Generoso, Jaqueline S; Simões, Lutiana R; Goularte, Jessica A; Petronilho, Fabricia; Saigal, Priyanka; Badawy, Marwa; Quevedo, João

    2016-04-01

    Bacterial meningitis is a life-threatening infection associated with cognitive impairment in many survivors. The pathogen invades the central nervous system (CNS) by penetrating through the luminal side of the cerebral endothelium, which is an integral part of the blood-brain barrier. The replication of bacteria within the subarachnoid space occurs concomitantly with the release of their compounds that are highly immunogenic. These compounds known as pathogen-associated molecular patterns (PAMPs) may lead to both an increase in the inflammatory response in the host and also microglial activation. Microglia are the resident macrophages of the CNS which, when activated, can trigger a host of immunological pathways. Classical activation increases the production of pro-inflammatory cytokines, chemokines, and reactive oxygen species, while alternative activation is implicated in the inhibition of inflammation and restoration of homeostasis. The inflammatory response from classical microglial activation can facilitate the elimination of invasive microorganisms; however, excessive or extended microglial activation can result in neuronal damage and eventually cell death. This review aims to discuss the role of microglia in the pathophysiology of bacterial meningitis as well as the process of microglial activation by PAMPs and by endogenous constituents that are normally released from damaged cells known as danger-associated molecular patterns (DAMPs). PMID:25744564

  5. Sesquiterpenes inhibiting the microglial activation from Laurus nobilis.

    PubMed

    Chen, Hongqiang; Xie, Chunfeng; Wang, Hao; Jin, Da-Qing; Li, Shen; Wang, Meicheng; Ren, Quanhui; Xu, Jing; Ohizumi, Yasushi; Guo, Yuanqiang

    2014-05-21

    The inhibitory reagents to inhibit the activation of microglial cells may be potentially useful for the treatment of neurodegenerative diseases. The leaves of the plant Laurus nobilis belonging to the family Lauraceae, namely, bay leaves, have been used as a popular spice, and their extract showed moderate inhibition on microglial activation. A further phytochemical investigation of the leaves led to the isolation of two new (1, 2) and eight known (3-10) sesquiterpenes. Their structures were elucidated on the basis of extensive 1D and 2D NMR (HMQC, HMBC, (1)H-(1)H COSY, and NOESY) spectroscopic data analyses and Chem3D modeling. The following biological studies disclosed that these isolated compounds showed inhibitory activities on LPS-induced microglial activation. The results of our phytochemical investigation, including two new sesquiterpenes (1 and 2) and the first report of two compounds (3 and 4) from this species, further revealed the chemical composition of bay leaves as a popular spice, and the biological studies implied that bay leaves, containing bioactive substances with the inhibition of microglial activation, were potentially beneficial to human health. PMID:24801989

  6. Fyn Kinase Regulates Microglial Neuroinflammatory Responses in Cell Culture and Animal Models of Parkinson's Disease

    PubMed Central

    Panicker, Nikhil; Saminathan, Hariharan; Jin, Huajun; Neal, Matthew; Harischandra, Dilshan S.; Gordon, Richard; Kanthasamy, Kavin; Lawana, Vivek; Sarkar, Souvarish; Luo, Jie; Anantharam, Vellareddy; Kanthasamy, Anumantha G.

    2015-01-01

    Sustained neuroinflammation mediated by resident microglia is recognized as a key pathophysiological contributor to many neurodegenerative diseases, including Parkinson's disease (PD), but the key molecular signaling events regulating persistent microglial activation have yet to be clearly defined. In the present study, we examined the role of Fyn, a non-receptor tyrosine kinase, in microglial activation and neuroinflammatory mechanisms in cell culture and animal models of PD. The well-characterized inflammogens LPS and TNFα rapidly activated Fyn kinase in microglia. Immunocytochemical studies revealed that activated Fyn preferentially localized to the microglial plasma membrane periphery and the nucleus. Furthermore, activated Fyn phosphorylated PKCδ at tyrosine residue 311, contributing to an inflammogen-induced increase in its kinase activity. Notably, the Fyn-PKCδ signaling axis further activated the LPS- and TNFα-induced MAP kinase phosphorylation and activation of the NFκB pathway, implying that Fyn is a major upstream regulator of proinflammatory signaling. Functional studies in microglia isolated from wild-type (Fyn+/+) and Fyn knock-out (Fyn−/−) mice revealed that Fyn is required for proinflammatory responses, including cytokine release as well as iNOS activation. Interestingly, a prolonged inflammatory insult induced Fyn transcript and protein expression, indicating that Fyn is upregulated during chronic inflammatory conditions. Importantly, in vivo studies using MPTP, LPS, or 6-OHDA models revealed a greater attenuation of neuroinflammatory responses in Fyn−/− and PKCδ −/− mice compared with wild-type mice. Collectively, our data demonstrate that Fyn is a major upstream signaling mediator of microglial neuroinflammatory processes in PD. SIGNIFICANCE STATEMENT Parkinson's disease (PD) is a complex multifactorial disease characterized by the progressive loss of midbrain dopamine neurons. Sustained microglia-mediated neuroinflammation has

  7. Low-level laser therapy regulates microglial function through Src-mediated signaling pathways: implications for neurodegenerative diseases

    PubMed Central

    2012-01-01

    Background Activated microglial cells are an important pathological component in brains of patients with neurodegenerative diseases. The purpose of this study was to investigate the effect of He-Ne (632.8 nm, 64.6 mW/cm2) low-level laser therapy (LLLT), a non-damaging physical therapy, on activated microglia, and the subsequent signaling events of LLLT-induced neuroprotective effects and phagocytic responses. Methods To model microglial activation, we treated the microglial BV2 cells with lipopolysaccharide (LPS). For the LLLT-induced neuroprotective study, neuronal cells with activated microglial cells in a Transwell™ cell-culture system were used. For the phagocytosis study, fluorescence-labeled microspheres were added into the treated microglial cells to confirm the role of LLLT. Results Our results showed that LLLT (20 J/cm2) could attenuate toll-like receptor (TLR)-mediated proinflammatory responses in microglia, characterized by down-regulation of proinflammatory cytokine expression and nitric oxide (NO) production. LLLT-triggered TLR signaling inhibition was achieved by activating tyrosine kinases Src and Syk, which led to MyD88 tyrosine phosphorylation, thus impairing MyD88-dependent proinflammatory signaling cascade. In addition, we found that Src activation could enhance Rac1 activity and F-actin accumulation that typify microglial phagocytic activity. We also found that Src/PI3K/Akt inhibitors prevented LLLT-stimulated Akt (Ser473 and Thr308) phosphorylation and blocked Rac1 activity and actin-based microglial phagocytosis, indicating the activation of Src/PI3K/Akt/Rac1 signaling pathway. Conclusions The present study underlines the importance of Src in suppressing inflammation and enhancing microglial phagocytic function in activated microglia during LLLT stimulation. We have identified a new and important neuroprotective signaling pathway that consists of regulation of microglial phagocytosis and inflammation under LLLT treatment. Our research

  8. Human neuromelanin: an endogenous microglial activator for dopaminergic neuron death

    PubMed Central

    Zhang, Wei; Zecca, Luigi; Wilson, Belinda; Ren, RW; Wang, Yong-jun; Wang, Xiao-min; Hong, Jau-Shyong

    2013-01-01

    Substantial evidence indicates that neuroinflammation caused by over-activation of microglial in the substantia nigra is critical in the pathogenesis of dopaminergic neurodegeneration in Parkinson’s disease (PD). Increasing data demonstrates that environmental factors such as rotenone, paraquat play pivotal roles in the death of dopaminergic neurons. Here, potential role and mechanism of neuromelanin (NM), a major endogenous component in dopaminergic neurons of the substantia nigra, on microglial activation and associated dopaminergic neurotoxicity were investigated. Using multiple well-established primary mesencephalic cultures, we tested whether human NM (HNM) could activate microglia, thereby provoking dopaminergic neurodegeneration. The results demonstrated that in primary mesencephalic neuron-glia cultures, HNM caused dopaminergic neuronal damage characterized by the decreased dopamine uptake and reduced numbers and shorted dendrites of dopaminergic neurons. HNM-induced degeneration was relatively selective to dopaminergic neurons since the other types of neurons determined by either gamma-aminobutyric acid uptake and total neuronal numbers after staining showed smaller decrease. We demonstrated that HNM produced modest dopaminergic neurotoxicity in neuron-enriched cultures; in contrast, much greater neurotoxicity was observed in the presence of microglia. HNM-induced microglial activation was shown by morphological changes and production of proinflammatory and neurotoxic factors. These results suggest that HNM, once released from damaged dopaminergic neurons, can be an potent endogenous activator involved in the reactivation of microglia, which may mediate disease progression. Thus, inhibition of reactive microglia can be a useful strategy for PD therapy. PMID:23276965

  9. Microglial activation and increased synthesis of complement component C1q precedes blood-brain barrier dysfunction in rats.

    PubMed

    Lynch, Nicholas J; Willis, Colin L; Nolan, Christopher C; Roscher, Silke; Fowler, Maxine J; Weihe, Eberhard; Ray, David E; Schwaeble, Wilhelm J

    2004-01-01

    A reliable way to visualise the state of microglial activation is to monitor the microglial gene expression profile. Microglia are the only CNS resident cells that synthesise C1q, the recognition sub-component of the classical complement pathway, in vivo. C1q biosynthesis in resting ramified microglia is often low, but it increases dramatically in activated microglia. In this study, the expression of C1q was used to monitor microglial activation at all stages of 3-chloropropanediol-induced neurotoxicity, a new model of blood-brain barrier (BBB) breakdown. In rats, 3-chloropropanediol produces very focused lesions in the brain, characterised by early astrocyte swelling and loss, followed by neuronal death and barrier dysfunction. Using in situ hybridisation, immunohistochemistry, and real-time RT-PCR, we found that increased C1q biosynthesis and microglial activation precede BBB dysfunction by at least 18 and peak 48 h after injection of 3-chloropropanediol, which coincides with the onset of active haemorrhage. Microglial activation is biphasic; an early phase of global activation is followed by a later phase in which microglial activation becomes increasingly focused in the lesions. During the early phase, expression of the pro-inflammatory mediators interleukin-1beta (IL1beta), tumour necrosis factor alpha (TNFalpha) and early growth response-1 (Egr-1) increased in parallel with C1q, but was restricted to the lesions. Expression of C1q (but not IL1beta, TNFalpha or Egr-1) remains high after BBB function is restored, and is accompanied by late up-regulation of the C1q-associated serine proteases, C1r and C1s, suggesting that microglial biosynthesis of the activation complex of the classical pathway may support the removal of cell debris by activation of complement. PMID:14644096

  10. Are Microglial Cells the Regulators of Lymphocyte Responses in the CNS?

    PubMed Central

    Almolda, Beatriz; González, Berta; Castellano, Bernardo

    2015-01-01

    The infiltration of immune cells in the central nervous system is a common hallmark in different neuroinflammatory conditions. Accumulating evidence indicates that resident glial cells can establish a cross-talk with infiltrated immune cells, including T-cells, regulating their recruitment, activation and function within the CNS. Although the healthy CNS has been thought to be devoid of professional dendritic cells (DCs), numerous studies have reported the presence of a population of DCs in specific locations such as the meninges, choroid plexuses and the perivascular space. Moreover, the infiltration of DC precursors during neuroinflammatory situations has been proposed, suggesting a putative role of these cells in the regulation of lymphocyte activity within the CNS. On the other hand, under specific circumstances, microglial cells are able to acquire a phenotype of DC expressing a wide range of molecules that equip these cells with all the necessary machinery for communication with T-cells. In this review, we summarize the current knowledge on the expression of molecules involved in the cross-talk with T-cells in both microglial cells and DCs and discuss the potential contribution of each of these cell populations on the control of lymphocyte function within the CNS. PMID:26635525

  11. Fibrillar Amyloid Plaque Formation Precedes Microglial Activation

    PubMed Central

    Steinbach, Sonja; Blazquez-Llorca, Lidia; Herms, Jochen

    2015-01-01

    In Alzheimer’s disease (AD), hallmark β-amyloid deposits are characterized by the presence of activated microglia around them. Despite an extensive characterization of the relation of amyloid plaques with microglia, little is known about the initiation of this interaction. In this study, the detailed investigation of very small plaques in brain slices in AD transgenic mice of the line APP-PS1(dE9) revealed different levels of microglia recruitment. Analysing plaques with a diameter of up to 10 μm we find that only the half are associated with clear morphologically activated microglia. Utilizing in vivo imaging of new appearing amyloid plaques in double-transgenic APP-PS1(dE9)xCX3CR1+/- mice further characterized the dynamic of morphological microglia activation. We observed no correlation of morphological microglia activation and plaque volume or plaque lifetime. Taken together, our results demonstrate a very prominent variation in size as well as in lifetime of new plaques relative to the state of microglia reaction. These observations might question the existing view that amyloid deposits by themselves are sufficient to attract and activate microglia in vivo. PMID:25799372

  12. Molecular Imaging of Microglial Activation in Amyotrophic Lateral Sclerosis

    PubMed Central

    Corcia, Philippe; Tauber, Clovis; Vercoullie, Johnnie; Arlicot, Nicolas; Prunier, Caroline; Praline, Julien; Nicolas, Guillaume; Venel, Yann; Hommet, Caroline; Baulieu, Jean-Louis; Cottier, Jean-Philippe; Roussel, Catherine; Kassiou, Mickael; Guilloteau, Denis; Ribeiro, Maria-Joao

    2012-01-01

    There is growing evidence of activated microglia and inflammatory processes in the cerebral cortex in amyotrophic lateral sclerosis (ALS). Activated microglia is characterized by increased expression of the 18 kDa translocator protein (TSPO) in the brain and may be a useful biomarker of inflammation. In this study, we evaluated neuroinflammation in ALS patients using a radioligand of TSPO, 18F-DPA-714. Ten patients with probable or definite ALS (all right-handed, without dementia, and untreated by riluzole or other medication that might bias the binding on the TSPO), were enrolled prospectively and eight healthy controls matched for age underwent a PET study. Comparison of the distribution volume ratios between both groups were performed using a Mann-Whitney’s test. Significant increase of distribution of volume ratios values corresponding to microglial activation was found in the ALS sample in primary motor, supplementary motor and temporal cortex (p = 0.009, p = 0.001 and p = 0.004, respectively). These results suggested that the cortical uptake of 18F-DPA-714 was increased in ALS patients during the “time of diagnosis” phase of the disease. This finding might improve our understanding of the pathophysiology of ALS and might be a surrogate marker of efficacy of treatment on microglial activation. PMID:23300829

  13. Resveratrol attenuates hypoxia-induced neurotoxicity through inhibiting microglial activation.

    PubMed

    Zhang, Qun; Yuan, Lin; Zhang, Qingrui; Gao, Yan; Liu, Guangheng; Xiu, Meng; Wei, Xiang; Wang, Zhen; Liu, Dexiang

    2015-09-01

    Resveratrol is a natural polyphenol enriched in Polygonum cuspidatum and has been found to afford neuroprotective effects against neuroinflammation in the brain. Activated microglia can secrete various pro-inflammatory cytokines and neurotoxic mediators, which may contribute to hypoxic brain injuries. The aim of this study is to investigate the potential role of resveratrol in attenuating hypoxia-induced neurotoxicity via its anti-inflammatory actions through in vitro models of the BV-2 microglial cell line and primary microglia. We found that resveratrol significantly inhibited hypoxia-induced microglial activation and reduced subsequent release of pro-inflammatory factors. In addition, resveratrol inhibited the hypoxia-induced degradation of IκB-alpha and phosphorylation of p65 NF-κB protein. Hypoxia-induced ERK1/2 and JNK phosphorylation was also strongly inhibited by resveratrol, whereas resveratrol had no effect on hypoxia-stimulated p38 MAPK phosphorylation. Importantly, treating primary cortical neurons with conditioned medium (CM) from hypoxia-stimulated microglia induced neuronal apoptosis, which was reversed by CM co-treated with resveratrol. Taken together, resveratrol exerts neuroprotection against hypoxia-induced neurotoxicity through its anti-inflammatory effects in microglia. These effects were mediated, at least in part, by suppressing the activation of NF-ĸB, ERK and JNK MAPK signaling pathways. PMID:26225925

  14. Quetiapine Inhibits Microglial Activation by Neutralizing Abnormal STIM1-Mediated Intercellular Calcium Homeostasis and Promotes Myelin Repair in a Cuprizone-Induced Mouse Model of Demyelination

    PubMed Central

    Wang, Hanzhi; Liu, Shubao; Tian, Yanping; Wu, Xiyan; He, Yangtao; Li, Chengren; Namaka, Michael; Kong, Jiming; Li, Hongli; Xiao, Lan

    2015-01-01

    Microglial activation has been considered as a crucial process in the pathogenesis of neuroinflammation and psychiatric disorders. Several antipsychotic drugs (APDs) have been shown to display inhibitory effects on microglial activation in vitro, possibly through the suppression of elevated intracellular calcium (Ca2+) concentration. However, the exact underlying mechanisms still remain elusive. In this study, we aimed to investigate the inhibitory effects of quetiapine (Que), an atypical APD, on microglial activation. We utilized a chronic cuprizone (CPZ)-induced demyelination mouse model to determine the direct effect of Que on microglial activation. Our results showed that treatment with Que significantly reduced recruitment and activation of microglia/macrophage in the lesion of corpus callosum and promoted remyelination after CPZ withdrawal. Our in vitro studies also confirmed the direct effect of Que on lipopolysaccharide (LPS)-induced activation of microglial N9 cells, whereby Que significantly inhibited the release of nitric oxide (NO) and tumor necrosis factor α (TNF-α). Moreover, we demonstrated that pretreatment with Que, neutralized the up-regulation of STIM1 induced by LPS and declined both LPS and thapsigargin (Tg)-induced store-operated Ca2+ entry (SOCE). Finally, we found that pretreatment with Que significantly reduced the translocation of nuclear factor kappa B (NF-κB) p65 subunit from cytoplasm to nuclei in LPS-activated primary microglial cells. Overall, our data suggested that Que may inhibit microglial activation by neutralization of the LPS-induced abnormal STIM1-mediated intercellular calcium homeostasis. PMID:26732345

  15. Donepezil Regulates 1-Methyl-4-phenylpyridinium-Induced Microglial Polarization in Parkinson's Disease.

    PubMed

    Chen, Teng; Hou, Ruihua; Xu, Shujun; Wu, Chengyuan

    2015-10-21

    1-Methyl-4-phenylpyridinium (MPP+) induces microglial activation and degeneration of dopaminergic (DAergic) neurons. Donepezil is a well-known acetylcholinesterase inhibitor used clinically to treat cognitive dysfunction in Alzheimer's disease (AD). In the present study, we tested the hypothesis that MPP+ promotes microglial M1 polarization and suppresses M2 polarization and that this can be restored by donepezil. Results indicate that MPP+ treatment in microglial BV2 cells promotes microglial polarization toward the M1 state. However, pretreatment with donepezil inhibited MPP+-induced M1 polarization in microglia by suppressing the release of interleukin (IL)-6, IL-1β, or tumor necrosis factor (TNF)-α. Importantly, we found that MPP+ inhibited microglial M2 polarization by suppressing expression of Arg-1, Fizz1, and Ym1, which was also rescued by pretreatment with donepezil. In addition, IL-4-mediated induction of anti-inflammatory marker genes IL-10, IL-13, and transforming growth factor-β2 (TGF-β2) were significantly attenuated by MPP+ in BV2 cells, which was restored by pretreatment with donepezil in a concentration-dependent manner. Mechanistically, we found that the addition of MPP+ reduced the intensity of phosphorylated signal transducer and activator of transcription 6 (STAT6) but not total STAT6 in IL-4-stimulated BV2 cells. Importantly, pretreatment of microglial BV2 cells with donepezil 3 h prior to administration of MPP+ rescued the reduction of STAT6 phosphorylation induced by MPP+. PMID:26114860

  16. Activation of serotonin receptors promotes microglial injury-induced motility but attenuates phagocytic activity.

    PubMed

    Krabbe, Grietje; Matyash, Vitali; Pannasch, Ulrike; Mamer, Lauren; Boddeke, Hendrikus W G M; Kettenmann, Helmut

    2012-03-01

    Microglia, the brain immune cell, express several neurotransmitter receptors which modulate microglial functions. In this project we studied the impact of serotonin receptor activation on distinct microglial properties as serotonin deficiency not only has been linked to a number of psychiatric disease like depression and anxiety but may also permeate from the periphery through blood-brain barrier openings seen in neurodegenerative disease. First, we tested the impact of serotonin on the microglial response to an insult caused by a laser lesion in the cortex of acute slices from Cx3Cr1-GFP-/+ mice. In the presence of serotonin the microglial processes moved more rapidly towards the laser lesion which is considered to be a chemotactic response to ATP. Similarly, the chemotactic response of cultured microglia to ATP was also enhanced by serotonin. Quantification of phagocytic activity by determining the uptake of microspheres showed that the amoeboid microglia in slices from early postnatal animals or microglia in culture respond to serotonin application with a decreased phagocytic activity whereas we could not detect any significant change in ramified microglia in situ. The presence of microglial serotonin receptors was confirmed by patch-clamp experiments in culture and amoeboid microglia and by qPCR analysis of RNA isolated from primary cultured and acutely isolated adult microglia. These data suggest that microglia express functional serotonin receptors linked to distinct microglial properties. PMID:22198120

  17. The antiviral drug ganciclovir does not inhibit microglial proliferation and activation

    PubMed Central

    Skripuletz, Thomas; Salinas Tejedor, Laura; Prajeeth, Chittappen K.; Hansmann, Florian; Chhatbar, Chintan; Kucman, Valeria; Zhang, Ning; Raddatz, Barbara B.; Detje, Claudia N.; Sühs, Kurt-Wolfram; Pul, Refik; Gudi, Viktoria; Kalinke, Ulrich; Baumgärtner, Wolfgang; Stangel, Martin

    2015-01-01

    Ganciclovir is effective in the treatment of human infections with viruses of the Herpesviridae family. Beside antiviral properties, recently ganciclovir was described to inhibit microglial proliferation and disease severity of experimental autoimmune encephalomyelitis, an inflammatory model of multiple sclerosis. Microglial activation and proliferation are main characteristics of neuroinflammatory CNS diseases and inhibition of microglial functions might be beneficial in autoimmune diseases, or detrimental in infectious diseases. The objective of this study was to determine potential inhibitory effects of ganciclovir in three different murine animal models of CNS neuroinflammation in which microglia play an important role: Theiler´s murine encephalomyelitis, the cuprizone model of de- and remyelination, and the vesicular stomatitis virus encephalitis model. In addition, in vitro experiments with microglial cultures were performed to test the hypothesis that ganciclovir inhibits microglial proliferation. In all three animal models, neither microglial proliferation or recruitment nor disease activity was changed by ganciclovir. In vitro experiments confirmed that microglial proliferation was not affected by ganciclovir. In conclusion, our results show that the antiviral drug ganciclovir does not inhibit microglial activation and proliferation in the murine CNS. PMID:26447351

  18. The antiviral drug ganciclovir does not inhibit microglial proliferation and activation.

    PubMed

    Skripuletz, Thomas; Salinas Tejedor, Laura; Prajeeth, Chittappen K; Hansmann, Florian; Chhatbar, Chintan; Kucman, Valeria; Zhang, Ning; Raddatz, Barbara B; Detje, Claudia N; Sühs, Kurt-Wolfram; Pul, Refik; Gudi, Viktoria; Kalinke, Ulrich; Baumgärtner, Wolfgang; Stangel, Martin

    2015-01-01

    Ganciclovir is effective in the treatment of human infections with viruses of the Herpesviridae family. Beside antiviral properties, recently ganciclovir was described to inhibit microglial proliferation and disease severity of experimental autoimmune encephalomyelitis, an inflammatory model of multiple sclerosis. Microglial activation and proliferation are main characteristics of neuroinflammatory CNS diseases and inhibition of microglial functions might be beneficial in autoimmune diseases, or detrimental in infectious diseases. The objective of this study was to determine potential inhibitory effects of ganciclovir in three different murine animal models of CNS neuroinflammation in which microglia play an important role: Theiler´s murine encephalomyelitis, the cuprizone model of de- and remyelination, and the vesicular stomatitis virus encephalitis model. In addition, in vitro experiments with microglial cultures were performed to test the hypothesis that ganciclovir inhibits microglial proliferation. In all three animal models, neither microglial proliferation or recruitment nor disease activity was changed by ganciclovir. In vitro experiments confirmed that microglial proliferation was not affected by ganciclovir. In conclusion, our results show that the antiviral drug ganciclovir does not inhibit microglial activation and proliferation in the murine CNS. PMID:26447351

  19. In vivo dynamics of retinal microglial activation during neurodegeneration: confocal ophthalmoscopic imaging and cell morphometry in mouse glaucoma

    PubMed Central

    Bosco, Alejandra; Romero, Cesar R; Ambati, Balamurali K; Vetter, Monica L

    2015-01-01

    SHORT ABSTRACT Microglia activation and microgliosis are key responses to chronic neurodegeneration. Here, we present methods for in vivo, long-term visualization of retinal CX3CR1-GFP+ microglial cells by confocal ophthalmoscopy, and for threshold and morphometric analyses to identify and quantify their activation. We monitor microglial changes during early stages of age-related glaucoma. LONG ABSTRACT Microglia, which are CNS-resident neuroimmune cells, transform their morphology and size in response to CNS damage, switching to an activated state with distinct functions and gene expression profiles. The roles of microglial activation in health, injury and disease remain incompletely understood due to their dynamic and complex regulation in response to changes in their microenvironment. Thus, it is critical to non-invasively monitor and analyze changes in microglial activation over time in the intact organism. In vivo studies of microglial activation have been delayed by technical limitations to tracking microglial behavior without altering the CNS environment. This has been particularly challenging during chronic neurodegeneration, where long-term changes must be tracked. The retina, a CNS organ amenable to non-invasive live imaging, offers a powerful system to visualize and characterize the dynamics of microglia activation during chronic disorders. This protocol outlines methods for long-term, in vivo imaging of retinal microglia, using confocal ophthalmoscopy (cSLO) and CX3CR1-GFPGFP/+ reporter mice, to visualize microglia with cellular resolution. Also, we describe methods to quantify monthly changes in cell activation and density in large cell subsets (200–300 cells per retina). We confirm the use of somal area as a useful metric for live tracking of microglial activation in the retina by applying automated threshold-based morphometric analysis of in vivo images. We use these live image acquisition and analyses strategies to monitor the dynamic changes in

  20. The role of microglial activation in disease progression.

    PubMed

    Correale, Jorge

    2014-09-01

    Microglia, a unique type of myeloid cell, play a key role in the inflammation-mediated neurodegeneration occurring during both acute and chronic stages of multiple sclerosis (MS). These highly specialized cells trigger neurotoxic pathways, producing pro-inflammatory cytokines, reactive oxygen and nitrogen species and proteolytic enzymes, causing progressive neurodegeneration. Microglia have also been associated with development of cortical lesions in progressive MS, as well as with alterations of synaptic transmission in experimental autoimmune encephalomyelitis (EAE). However, they also play an important role in the promotion of neuroprotection, downregulation of inflammation, and stimulation of tissue repair. Notably, microglia undergo changes in morphology and function with normal aging, resulting in a decline of their ability to repair central nervous system damage, making axons and neurons more vulnerable with age. Modulation of microglial activation for therapeutic purposes must consider suppressing deleterious effects of these cells, while simultaneously preserving their protective functions. PMID:24812046

  1. C1q, the recognition subcomponent of the classical pathway of complement, drives microglial activation.

    PubMed

    Färber, Katrin; Cheung, Giselle; Mitchell, Daniel; Wallis, Russell; Weihe, Eberhard; Schwaeble, Wilhelm; Kettenmann, Helmut

    2009-02-15

    Microglia, central nervous system (CNS) resident phagocytic cells, persistently police the integrity of CNS tissue and respond to any kind of damage or pathophysiological changes. These cells sense and rapidly respond to danger and inflammatory signals by changing their cell morphology; by release of cytokines, chemokines, or nitric oxide; and by changing their MHC expression profile. We have shown previously that microglial biosynthesis of the complement subcomponent C1q may serve as a reliable marker of microglial activation ranging from undetectable levels of C1q biosynthesis in resting microglia to abundant C1q expression in activated, nonramified microglia. In this study, we demonstrate that cultured microglial cells respond to extrinsic C1q with a marked intracellular Ca(2+) increase. A shift toward proinflammatory microglial activation is indicated by the release of interleukin-6, tumor necrosis factor-alpha, and nitric oxide and the oxidative burst in rat primary microglial cells, an activation and differentiation process similar to the proinflammatory response of microglia to exposure to lipopolysaccharide. Our findings indicate 1) that extrinsic plasma C1q is involved in the initiation of microglial activation in the course of CNS diseases with blood-brain barrier impairment and 2) that C1q synthesized and released by activated microglia is likely to contribute in an autocrine/paracrine way to maintain and balance microglial activation in the diseased CNS tissue. PMID:18831010

  2. TMEM16F Regulates Spinal Microglial Function in Neuropathic Pain States.

    PubMed

    Batti, Laura; Sundukova, Mayya; Murana, Emanuele; Pimpinella, Sofia; De Castro Reis, Fernanda; Pagani, Francesca; Wang, Hong; Pellegrino, Eloisa; Perlas, Emerald; Di Angelantonio, Silvia; Ragozzino, Davide; Heppenstall, Paul A

    2016-06-21

    Neuropathic pain is a widespread chronic pain state that results from injury to the nervous system. Spinal microglia play a causative role in the pathogenesis of neuropathic pain through secretion of growth factors and cytokines. Here, we investigated the contribution of TMEM16F, a protein that functions as a Ca(2+)-dependent ion channel and a phospholipid scramblase, to microglial activity during neuropathic pain. We demonstrate that mice with a conditional ablation of TMEM16F in microglia do not develop mechanical hypersensitivity upon nerve injury. In the absence of TMEM16F, microglia display deficits in process motility and phagocytosis. Moreover, loss of GABA immunoreactivity upon injury is spared in TMEM16F conditional knockout mice. Collectively, these data indicate that TMEM16F is an essential component of the microglial response to injury and suggest the importance of microglial phagocytosis in the pathogenesis of neuropathic pain. PMID:27332874

  3. The Role of MAC1 in Diesel Exhaust Particle-induced Microglial Activation and Loss of Dopaminergic Neuron Function

    PubMed Central

    Levesque, Shannon; Taetzsch, Thomas; Lull, Melinda E.; Johnson, Jo Anne; McGraw, Constance; Block, Michelle L.

    2013-01-01

    Increasing reports support that air pollution causes neuroinflammation and is linked to central nervous system (CNS) disease/damage. Diesel exhaust particles (DEP) are a major component of urban air pollution, which has been linked to microglial activation and Parkinson’s disease-like pathology. To begin to address how DEP may exert CNS effects, microglia and neuron-glia cultures were treated with either nanometer-sized DEP (<0.22 µM; 50µg/mL), ultrafine carbon black (ufCB, 50µg/ml), or DEP extracts (eDEP; from 50 µg/ml DEP) and the effect of microglial activation and dopaminergic (DA) neuron function was assessed. All three treatments showed enhanced amoeboid microglia morphology, increased H2O2 production, and decreased DA uptake. Mechanistic inquiry revealed that the scavenger receptor inhibitor fucoidan blocked DEP internalization in microglia, but failed to alter DEP-induced H2O2 production in microglia. However, pretreatment with the MAC1/CD11b inhibitor antibody blocked microglial H2O2 production in response to DEP. MAC1−/− mesencephalic neuron-glia cultures were protected from DEP-induced loss of DA neuron function, as measured by DA uptake. These findings support that DEP may activate microglia through multiple mechanisms, where scavenger receptors regulate internalization of DEP and the MAC1 receptor is mandatory for both DEP-induced microglial H2O2 production and loss of DA neuron function. PMID:23470120

  4. Microglial activation induces neuronal death in Chandipura virus infection

    PubMed Central

    Verma, Abhishek Kumar; Ghosh, Sourish; Pradhan, Sreeparna; Basu, Anirban

    2016-01-01

    Neurotropic viruses induce neurodegeneration either directly by activating host death domains or indirectly through host immune response pathways. Chandipura Virus (CHPV) belonging to family Rhabdoviridae is ranked among the emerging pathogens of the Indian subcontinent. Previously we have reported that CHPV induces neurodegeneration albeit the root cause of this degeneration is still an open question. In this study we explored the role of microglia following CHPV infection. Phenotypic analysis of microglia through lectin and Iba-1 staining indicated cells were in an activated state post CHPV infection in cortical region of the infected mouse brain. Cytokine Bead Array (CBA) analysis revealed comparatively higher cytokine and chemokine levels in the same region. Increased level of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), Nitric Oxide (NO) and Reactive Oxygen species (ROS) in CHPV infected mouse brain indicated a strong inflammatory response to CHPV infection. Hence it was hypothesized through our analyses that this inflammatory response may stimulate the neuronal death following CHPV infection. In order to validate our hypothesis supernatant from CHPV infected microglial culture was used to infect neuronal cell line and primary neurons. This study confirmed the bystander killing of neurons due to activation of microglia post CHPV infection. PMID:26931456

  5. Microglial Activation in Rat Experimental Spinal Cord Injury Model

    PubMed Central

    Abdanipour, Alireza; Tiraihi, Taki; Taheri, Taher; Kazemi, Hadi

    2013-01-01

    Background: The present study was designed to evaluate the secondary microglial activation processes after spinal cord injury (SCI). Methods: A quantitative histological study was performed to determine ED-1 positive cells, glial cell density, and cavitation size in untreated SCI rats at days 1, 2, and 4, and weeks 1, 2, 3, and 4. Results: The results of glial cell quantification along the 4900-µm long injured spinal cord showed a significant increase in glial cell density percentage at day 2 as compared to other days. Whereas the highest increase in ED-1 immunoreactive cells (monocyte/phagocyte marker in rats) was observed at day 2 (23.15%) post-injury. Evaluation of cavity percentage showed a significant difference between weeks 3 and 4 post-injury groups. Conclusions: This study provides a new insight into the multiphase immune response to SCI, including cellular inflammation, macrophages/microglia activation, glial cell density, and cavitation. Better understanding of the inflammatory processes associated with acute SCI would permit the development of better therapeutic strategies. PMID:23999718

  6. Differential effects of stress on microglial cell activation in male and female medial prefrontal cortex.

    PubMed

    Bollinger, Justin L; Bergeon Burns, Christine M; Wellman, Cara L

    2016-02-01

    Susceptibility to stress-linked psychological disorders, including post-traumatic stress disorder and depression, differs between men and women. Dysfunction of medial prefrontal cortex (mPFC) has been implicated in many of these disorders. Chronic stress affects mPFC in a sex-dependent manner, differentially remodeling dendritic morphology and disrupting prefrontally mediated behaviors in males and females. Chronic restraint stress induces microglial activation, reflected in altered microglial morphology and immune factor expression, in mPFC in male rats. Unstressed females exhibit increased microglial ramification in several brain regions compared to males, suggesting both heightened basal activation and a potential for sex-dependent effects of stress on microglial activation. Therefore, we assessed microglial density and ramification in the prelimbic region of mPFC, and immune-associated genes in dorsal mPFC in male and female rats following acute or chronic restraint stress. Control rats were left unstressed. On the final day of restraint, brains were collected for either qPCR or visualization of microglia using Iba-1 immunohistochemistry. Microglia in mPFC were classified as ramified, primed, reactive, or amoeboid, and counted stereologically. Expression of microglia-associated genes (MHCII, CD40, IL6, CX3CL1, and CX3CR1) was also assessed using qPCR. Unstressed females showed a greater proportion of primed to ramified microglia relative to males, alongside heightened CX3CL1-CX3CR1 expression. Acute and chronic restraint stress reduced the proportion of primed to ramified microglia and microglial CD40 expression in females, but did not significantly alter microglial activation in males. This sex difference in microglial activation could contribute to the differential effects of stress on mPFC structure and function in males versus females. PMID:26441134

  7. Differential Effects of Stress on Microglial Cell Activation in Male and Female Medial Prefrontal Cortex

    PubMed Central

    Bollinger, Justin L.; Bergeon Burns, Christine M.; Wellman, Cara L.

    2016-01-01

    Susceptibility to stress-linked psychological disorders, including post-traumatic stress disorder and depression, differs between men and women. Dysfunction of medial prefrontal cortex (mPFC) has been implicated in many of these disorders. Chronic stress affects mPFC in a sex-dependent manner, differentially remodeling dendritic morphology and disrupting prefrontally mediated behaviors in males and females. Chronic restraint stress induces microglial activation, reflected in altered microglial morphology and immune factor expression, in mPFC in male rats. Unstressed females exhibit increased microglial ramification in several brain regions compared to males, suggesting both heightened basal activation and a potential for sex-dependent effects of stress on microglial activation. Therefore, we assessed microglial density and ramification in the prelimbic region of mPFC, and immune-associated genes in dorsal mPFC in male and female rats following acute or chronic restraint stress. Control rats were left unstressed. On the final day of restraint, brains were collected for either qPCR or visualization of microglia using Iba-1 immunohistochemistry. Microglia in mPFC were classified as ramified, primed, reactive, or amoeboid, and counted stereologically. Expression of microglia-associated genes (MHCII, CD40, IL6, CX3CL1, and CX3CR1) was also assessed using qPCR. Unstressed females showed a greater proportion of primed to ramified microglia relative to males, alongside heightened CX3CL1-CX3CR1 expression. Acute and chronic restraint stress reduced the proportion of primed to ramified microglia and microglial CD40 expression in females, but did not significantly alter microglial activation in males. This sex difference in microglial activation could contribute to the differential effects of stress on mPFC structure and function in males versus females. PMID:26441134

  8. Botanical Polyphenols Mitigate Microglial Activation and Microglia-Induced Neurotoxicity: Role of Cytosolic Phospholipase A2.

    PubMed

    Chuang, Dennis Y; Simonyi, Agnes; Cui, Jiankun; Lubahn, Dennis B; Gu, Zezong; Sun, Grace Y

    2016-09-01

    Microglia play a significant role in the generation and propagation of oxidative/nitrosative stress, and are the basis of neuroinflammatory responses in the central nervous system. Upon stimulation by endotoxins such as lipopolysaccharides (LPS), these cells release pro-inflammatory factors which can exert harmful effects on surrounding neurons, leading to secondary neuronal damage and cell death. Our previous studies demonstrated the effects of botanical polyphenols to mitigate inflammatory responses induced by LPS, and highlighted an important role for cytosolic phospholipase A2 (cPLA2) upstream of the pro-inflammatory pathways (Chuang et al. in J Neuroinflammation 12(1):199, 2015. doi: 10.1186/s12974-015-0419-0 ). In this study, we investigate the action of botanical compounds and assess whether suppression of cPLA2 in microglia is involved in the neurotoxic effects on neurons. Differentiated SH-SY5Y neuroblastoma cells were used to test the neurotoxicity of conditioned medium from stimulated microglial cells, and WST-1 assay was used to assess for the cell viability of SH-SY5Y cells. Botanicals such as quercetin and honokiol (but not cyanidin-3-O-glucoside, 3CG) were effective in inhibiting LPS-induced nitric oxide (NO) production and phosphorylation of cPLA2. Conditioned medium from BV-2 cells stimulated with LPS or IFNγ caused neurotoxicity to SH-SY5Y cells. Decrease in cell viability could be ameliorated by pharmacological inhibitors for cPLA2 as well as by down-regulating cPLA2 with siRNA. Botanicals effective in inhibition of LPS-induced NO and cPLA2 phosphorylation were also effective in ameliorating microglial-induced neurotoxicity. Results demonstrated cytotoxic factors from activated microglial cells to cause damaging effects to neurons and potential use of botanical polyphenols to ameliorate the neurotoxic effects. PMID:27339657

  9. Allergy Enhances Neurogenesis and Modulates Microglial Activation in the Hippocampus

    PubMed Central

    Klein, Barbara; Mrowetz, Heike; Thalhamer, Josef; Scheiblhofer, Sandra; Weiss, Richard; Aigner, Ludwig

    2016-01-01

    Allergies and their characteristic TH2-polarized inflammatory reactions affect a substantial part of the population. Since there is increasing evidence that the immune system modulates plasticity and function of the central nervous system (CNS), we investigated the effects of allergic lung inflammation on the hippocampus—a region of cellular plasticity in the adult brain. The focus of the present study was on microglia, the resident immune cells of the CNS, and on hippocampal neurogenesis, i.e., the generation of new neurons. C57BL/6 mice were sensitized with a clinically relevant allergen derived from timothy grass pollen (Phl p 5). As expected, allergic sensitization induced high serum levels of allergen-specific immunoglobulins (IgG1 and IgE) and of TH2 cytokines (IL-5 and IL-13). Surprisingly, fewer Iba1+ microglia were found in the granular layer (GL) and subgranular zone (SGZ) of the hippocampal dentate gyrus and also the number of Iba1+MHCII+ cells was lower, indicating a reduced microglial surveillance and activation in the hippocampus of allergic mice. Neurogenesis was analyzed by labeling of proliferating cells with bromodeoxyuridine (BrdU) and determining their fate 4 weeks later, and by quantitative analysis of young immature neurons, i.e., cells expressing doublecortin (DCX). The number of DCX+ cells was clearly increased in the allergy animals. Moreover, there were more BrdU+ cells present in the hippocampus of allergic mice, and these newly born cells had differentiated into neurons as indicated by a higher number of BrdU+NeuN+ cells. In summary, allergy led to a reduced microglia presence and activity and to an elevated level of neurogenesis in the hippocampus. This effect was apparently specific to the hippocampus, as we did not observe these alterations in the subventricular zone (SVZ)/olfactory bulb (OB) system, also a region of high cellular plasticity and adult neurogenesis. PMID:27445696

  10. Activation of murine microglial N9 cells is attenuated through cannabinoid receptor CB2 signaling.

    PubMed

    Ma, Lei; Jia, Ji; Liu, Xiangyu; Bai, Fuhai; Wang, Qiang; Xiong, Lize

    2015-02-27

    Inhibition of microglial activation is effective in treating various neurological disorders. Activation of microglial cannabinoid CB2 receptor induces anti-inflammatory effects, and the mechanism, however, is still elusive. Microglia could be activated into the classic activated state (M1 state) or the alternative activated state (M2 state), the former is cytotoxic, and the latter is neurotrophic. In this study, we used lipopolysaccharide (LPS) plus interferon-γ (IFNγ) to activate N9 microglia and hypothesized the pretreatment with cannabinoid CB2 receptor agonist AM1241 attenuates microglial activation by shifting microglial M1 to M2 state. We found that pretreatment with 5 μM AM1241 at 1 h before microglia were exposed to LPS plus IFNγ decreased the expression of inducible nitric oxide synthase (iNOS) and the release of pro-inflammatory factors, increased the expression of arginase 1 (Arg-1) and the release of anti-inflammatory and neurotrophic factors in microglia. However, these effects induced by AM1241 pretreatment were significantly reversed in the presence of 10 μM cannabinoid CB2 receptor antagonist AM630 or 10 μM protein kinase C (PKC) inhibitor chelerythrine. These findings indicated that AM1241 pretreatment attenuates microglial activation by shifting M1 to M2 activated state via CB2 receptor, and the AM1241-induced anti-inflammatory effects may be mediated by PKC. PMID:25637536

  11. The impact of microglial activation on blood-brain barrier in brain diseases

    PubMed Central

    da Fonseca, Anna Carolina Carvalho; Matias, Diana; Garcia, Celina; Amaral, Rackele; Geraldo, Luiz Henrique; Freitas, Catarina; Lima, Flavia Regina Souza

    2014-01-01

    The blood-brain barrier (BBB), constituted by an extensive network of endothelial cells (ECs) together with neurons and glial cells, including microglia, forms the neurovascular unit (NVU). The crosstalk between these cells guarantees a proper environment for brain function. In this context, changes in the endothelium-microglia interactions are associated with a variety of inflammation-related diseases in brain, where BBB permeability is compromised. Increasing evidences indicate that activated microglia modulate expression of tight junctions, which are essential for BBB integrity and function. On the other hand, the endothelium can regulate the state of microglial activation. Here, we review recent advances that provide insights into interactions between the microglia and the vascular system in brain diseases such as infectious/inflammatory diseases, epilepsy, ischemic stroke and neurodegenerative disorders. PMID:25404894

  12. Glycogen synthase kinase 3 is part of the molecular machinery regulating the adaptive response to LPS stimulation in microglial cells.

    PubMed

    Ajmone-Cat, Maria Antonietta; D'Urso, Maria Cristina; di Blasio, Giorgia; Brignone, Maria Stefania; De Simone, Roberta; Minghetti, Luisa

    2016-07-01

    Repeated stimulation of TLR4 signaling by lipopolysaccharide (LPS) in microglia induces a state of tolerance/sensitization consisting in the reprogramming of the expression of pro-inflammatory genes in favor of anti-inflammatory ones. The molecular mechanisms underlying this adaptive response are far to be elucidated. Glycogen synthase kinase 3 (GSK3) has emerged as crucial regulator of TLR signaling, mediating the balance between pro- and anti-inflammatory functions in both periphery and central nervous system. The present study extends this notion identifying GSK3 as part of the molecular machinery regulating the LPS-adaptive response in microglial cells, by using primary microglial cultures and organotypic hippocampal slices (OHSCs). We found that lithium chloride (LiCl), a widely used GSK3 inhibitor and the mainstay treatment for bipolar disorder, reinforced the LPS adaptive response by enhancing both downregulation of pro-inflammatory genes (inducible nitric oxide synthase, interleukin 1β, interleukin 6, tumor necrosis factor α), and upregulation of genes typically associated to anti-inflammatory functions (interleukin 10 and MRC1). The effects of GSK3 inhibition were mimicked by Wnt3a, added exogenously, and reversed by Inhibitor of Wnt-Response-1-endo, a pharmacological disruptor of the canonical Wnt/β-catenin pathway, and GW9662, a selective peroxisome proliferator activated receptor γ antagonist, suggesting that these two pathways are involved in the regulation of LPS-tolerance/sensitization by GSK. Finally, LiCl treatment of OHSCs enhanced the protective functional consequences of the microglial adaptive response to LPS on oligodendrocyte maturation, as indicated by MBP mRNA upregulation. These results further indicate GSK3 as key component in the orchestration of neuroinflammation and target for neuroprotective strategies. PMID:26593276

  13. Microglial p38α MAPK is a key regulator of proinflammatory cytokine up-regulation induced by toll-like receptor (TLR) ligands or beta-amyloid (Aβ)

    PubMed Central

    2011-01-01

    Background Overproduction of proinflammatory cytokines from activated microglia has been implicated as an important contributor to pathophysiology progression in both acute and chronic neurodegenerative diseases. Therefore, it is critical to elucidate intracellular signaling pathways that are significant contributors to cytokine overproduction in microglia exposed to specific stressors, especially pathways amenable to drug interventions. The serine/threonine protein kinase p38α MAPK is a key enzyme in the parallel and convergent intracellular signaling pathways involved in stressor-induced production of IL-1β and TNFα in peripheral tissues, and is a drug development target for peripheral inflammatory diseases. However, much less is known about the quantitative importance of microglial p38α MAPK in stressor-induced cytokine overproduction, or the potential of microglial p38α MAPK to be a druggable target for CNS disorders. Therefore, we examined the contribution of microglial p38αMAPK to cytokine up-regulation, with a focus on the potential to suppress the cytokine increase by inhibition of the kinase with pharmacological or genetic approaches. Methods The microglial cytokine response to TLR ligands 2/3/4/7/8/9 or to Aβ1-42 was tested in the presence of a CNS-penetrant p38α MAPK inhibitor, MW01-2-069A-SRM. Primary microglia from mice genetically deficient in p38α MAPK were used to further establish a linkage between microglia p38α MAPK and cytokine overproduction. The in vivo significance was determined by p38α MAPK inhibitor treatment in a LPS-induced model of acute neuroinflammation. Results Increased IL-1β and TNFα production by the BV-2 microglial cell line and by primary microglia cultures was inhibited in a concentration-dependent manner by the p38α MAPK-targeted inhibitor. Cellular target engagement was demonstrated by the accompanying decrease in the phosphorylation state of two p38α MAPK protein substrates, MK2 and MSK1. Consistent with the

  14. Role and Mechanism of Microglial Activation in Iron-Induced Selective and Progressive Dopaminergic Neurodegeneration

    PubMed Central

    Yan, Zhao-fen; Gao, Jun-hua; Sun, Li; Huang, Xi-yan; Liu, Zhuo; Yu, Shu-yang; Cao, Chen-Jie; Zuo, Li-jun; Chen, Ze-Jie; Hu, Yang; Wang, Fang; Hong, Jau-shyong; Wang, Xiao-min

    2016-01-01

    Parkinson’s disease (PD) patients have excessive iron depositions in substantia nigra (SN). Neuroinflammation characterized by microglial activation is pivotal for dopaminergic neurodegeneration in PD. However, the role and mechanism of microglial activation in iron-induced dopaminergic neurodegeneration in SN remain unclear yet. This study aimed to investigate the role and mechanism of microglial β-nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) activation in iron-induced selective and progressive dopaminergic neurodegeneration. Multiple primary midbrain cultures from rat, NOX2+/+ and NOX2−/− mice were used. Dopaminergic neurons, total neurons, and microglia were visualized by immunostainings. Cell viability was measured by MTT assay. Superoxide (O2·−) and intracellular reactive oxygen species (iROS) were determined by measuring SOD-inhibitable reduction of tetrazolium salt WST-1 and DCFH-DA assay. mRNA and protein were detected by real-time PCR and Western blot. Iron induces selective and progressive dopaminergic neurotoxicity in rat neuron–microglia–astroglia cultures and microglial activation potentiates the neurotoxicity. Activated microglia produce a magnitude of O2·− and iROS, and display morphological alteration. NOX2 inhibitor diphenylene iodonium protects against iron-elicited dopaminergic neurotoxicity through decreasing microglial O2·− generation, and NOX2−/− mice are resistant to the neurotoxicity by reducing microglial O2·− production, indicating that iron-elicited dopaminergic neurotoxicity is dependent of NOX2, a O2·−-generating enzyme. NOX2 activation is indicated by the increased mRNA and protein levels of subunits P47 and gp91. Molecules relevant to NOX2 activation include PKC-σ, P38, ERK1/2, JNK, and NF-ΚBP65 as their mRNA and protein levels are enhanced by NOX2 activation. Iron causes selective and progressive dopaminergic neurodegeneration, and microglial NOX2 activation potentiates the

  15. Docosahexaenoic acid modulates inflammatory and antineurogenic functions of activated microglial cells.

    PubMed

    Antonietta Ajmone-Cat, Maria; Lavinia Salvatori, Maria; De Simone, Roberta; Mancini, Melissa; Biagioni, Stefano; Bernardo, Antonietta; Cacci, Emanuele; Minghetti, Luisa

    2012-03-01

    The complex process of microglial activation encompasses several functional activation states associated either with neurotoxic/antineurogenic or with neurotrophic/proneurogenic properties, depending mainly on the extent of activation and the nature of the activating stimuli. Several studies have demonstrated that acute exposure to the prototypical activating agent lipopolysaccharide (LPS) confers antineurogenic properties upon microglial cells. Acutely activated microglia ortheir conditioned media (CM) reduce neural stem progenitor cell (NPC) survival and prevent NPC differentiation into neurons. The present study tested the hypothesis that docosahexaenoic acid (DHA), a long-chain polyunsatured fatty acid (L-PUFA) with potent immunomodulatory properties, could dampen microglial proinflammatory functions and modulate their antineurogenic effect. We demonstrate that DHA dose dependently inhibits the synthesis of inflammatory products in activated microglia without inducing an alternative antiinflammatory phenotype. Among the possible DHA mechanisms of action, we propose the inhibition of p38 MAPK phosphorylation and the activation of the nuclear receptor peroxisome proliferator activated receptor (PPAR)-γ. The attenuation of M1 proinflammatory phenotype has relevant consequences for the survival and differentiation of NPC, because DHA reverses the antineurogenic activities of conditioned media from LPS-activated microglia. Our study identifies new relevant potentially protective and proneurogenic functions of DHA, exerted through the modulation of microglial functions, that could be exploited to sustain or promote neuroregenerative processes in damaged/aged brain. PMID:22057807

  16. Donepezil inhibits the amyloid-beta oligomer-induced microglial activation in vitro and in vivo.

    PubMed

    Kim, Hyo Geun; Moon, Minho; Choi, Jin Gyu; Park, Gunhyuk; Kim, Ae-Jung; Hur, Jinyoung; Lee, Kyung-Tae; Oh, Myung Sook

    2014-01-01

    Recent studies on Alzheimer's disease (AD) have focused on soluble oligomeric forms of amyloid-beta (Aβ oligomer, AβO) that are directly associated with AD-related pathologies, such as cognitive decline, neurodegeneration, and neuroinflammation. Donepezil is a well-known anti-dementia agent that increases acetylcholine levels through inhibition of acetylcholinesterase. However, a growing body of experimental and clinical studies indicates that donepezil may also provide neuroprotective and disease-modifying effects in AD. Additionally, donepezil has recently been demonstrated to have anti-inflammatory effects against lipopolysaccharides and tau pathology. However, it remains unknown whether donepezil has anti-inflammatory effects against AβO in cultured microglial cells and the brain in animals. Further, the effects of donepezil against AβO-mediated neuronal death, astrogliosis, and memory impairment have also not yet been investigated. Thus, in the present study, we examined the anti-inflammatory effect of donepezil against AβO and its neuroinflammatory mechanisms. Donepezil significantly attenuated the release of inflammatory mediators (prostaglandin E2, interleukin-1 beta, tumor necrosis factor-α, and nitric oxide) from microglia. Donepezil also decreased AβO-induced up-regulation of inducible nitric oxide synthase and cyclooxygenase-2 protein and phosphorylation of p38 mitogen-activated protein kinase as well as translocation of nuclear factor-kappa B. We next showed that donepezil suppresses activated microglia-mediated toxicity in primary hippocampal cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. In intrahippocampal AβO-injected mice, donepezil significantly inhibited microgliosis and astrogliosis. Furthermore, behavioral tests revealed that donepezil (2 mg/kg/day, 5 days, p.o.) significantly ameliorated AβO-induced memory impairment. These results suggest that donepezil directly inhibits microglial activation

  17. Regulation of Macrophage, Dendritic Cell, and Microglial Phenotype and Function by the SOCS Proteins

    PubMed Central

    McCormick, Sarah M.; Heller, Nicola M.

    2015-01-01

    Macrophages are innate immune cells of dynamic phenotype that rapidly respond to external stimuli in the microenvironment by altering their phenotype to respond to and to direct the immune response. The ability to dynamically change phenotype must be carefully regulated to prevent uncontrolled inflammatory responses and subsequently to promote resolution of inflammation. The suppressor of cytokine signaling (SOCS) proteins play a key role in regulating macrophage phenotype. In this review, we summarize research to date from mouse and human studies on the role of the SOCS proteins in determining the phenotype and function of macrophages. We will also touch on the influence of the SOCS on dendritic cell (DC) and microglial phenotype and function. The molecular mechanisms of SOCS function in macrophages and DCs are discussed, along with how dysregulation of SOCS expression or function can lead to alterations in macrophage/DC/microglial phenotype and function and to disease. Regulation of SOCS expression by microRNA is discussed. Novel therapies and unanswered questions with regard to SOCS regulation of monocyte–macrophage phenotype and function are highlighted. PMID:26579124

  18. Factors regulating microglia activation

    PubMed Central

    Kierdorf, Katrin; Prinz, Marco

    2013-01-01

    Microglia are resident macrophages of the central nervous system (CNS) that display high functional similarities to other tissue macrophages. However, it is especially important to create and maintain an intact tissue homeostasis to support the neuronal cells, which are very sensitive even to minor changes in their environment. The transition from the “resting” but surveying microglial phenotype to an activated stage is tightly regulated by several intrinsic (e.g., Runx-1, Irf8, and Pu.1) and extrinsic factors (e.g., CD200, CX3CR1, and TREM2). Under physiological conditions, minor changes of those factors are sufficient to cause fatal dysregulation of microglial cell homeostasis and result in severe CNS pathologies. In this review, we discuss recent achievements that gave new insights into mechanisms that ensure microglia quiescence. PMID:23630462

  19. Olfactory Sensory Activity Modulates Microglial-Neuronal Interactions during Dopaminergic Cell Loss in the Olfactory Bulb.

    PubMed

    Grier, Bryce D; Belluscio, Leonardo; Cheetham, Claire E J

    2016-01-01

    The mammalian olfactory bulb (OB) displays robust activity-dependent plasticity throughout life. Dopaminergic (DA) neurons in the glomerular layer (GL) of the OB are particularly plastic, with loss of sensory input rapidly reducing tyrosine hydroxylase (TH) expression and dopamine production, followed by a substantial reduction in DA neuron number. Here, we asked whether microglia participate in activity-dependent elimination of DA neurons in the mouse OB. Interestingly, we found a significant reduction in the number of both DA neurons and their synapses in the OB ipsilateral to the occluded naris (occluded OB) within just 7 days of sensory deprivation. Concomitantly, the volume of the occluded OB decreased, resulting in an increase in microglial density. Microglia in the occluded OB also adopted morphologies consistent with activation. Using in vivo 2-photon imaging and histological analysis we then showed that loss of olfactory input markedly altered microglial-neuronal interactions during the time that DA neurons are being eliminated: both microglial process motility and the frequency of wrapping of DA neuron somata by activated microglia increased significantly in the occluded OB. Furthermore, we found microglia in the occluded OB that had completely engulfed components of DA neurons. Together, our data provide evidence that loss of olfactory input modulates microglial-DA neuron interactions in the OB, thereby suggesting an important role for microglia in the activity-dependent elimination of DA neurons and their synapses. PMID:27471450

  20. Olfactory Sensory Activity Modulates Microglial-Neuronal Interactions during Dopaminergic Cell Loss in the Olfactory Bulb

    PubMed Central

    Grier, Bryce D.; Belluscio, Leonardo; Cheetham, Claire E. J.

    2016-01-01

    The mammalian olfactory bulb (OB) displays robust activity-dependent plasticity throughout life. Dopaminergic (DA) neurons in the glomerular layer (GL) of the OB are particularly plastic, with loss of sensory input rapidly reducing tyrosine hydroxylase (TH) expression and dopamine production, followed by a substantial reduction in DA neuron number. Here, we asked whether microglia participate in activity-dependent elimination of DA neurons in the mouse OB. Interestingly, we found a significant reduction in the number of both DA neurons and their synapses in the OB ipsilateral to the occluded naris (occluded OB) within just 7 days of sensory deprivation. Concomitantly, the volume of the occluded OB decreased, resulting in an increase in microglial density. Microglia in the occluded OB also adopted morphologies consistent with activation. Using in vivo 2-photon imaging and histological analysis we then showed that loss of olfactory input markedly altered microglial-neuronal interactions during the time that DA neurons are being eliminated: both microglial process motility and the frequency of wrapping of DA neuron somata by activated microglia increased significantly in the occluded OB. Furthermore, we found microglia in the occluded OB that had completely engulfed components of DA neurons. Together, our data provide evidence that loss of olfactory input modulates microglial-DA neuron interactions in the OB, thereby suggesting an important role for microglia in the activity-dependent elimination of DA neurons and their synapses. PMID:27471450

  1. NANOMETER DIESEL EXHAUST PARTICLES ARE NEUROTOXIC TO DOPAMINERGIC NEURONS THROUGH MICROGLIAL ACTIVATION.

    EPA Science Inventory

    NANOMETER DIESEL EXHAUST PARTICLES ARE NEUROTOXIC TO DOPAMINERGIC NEURONS THROUGH MICROGLIAL ACTIVATION. M.L. Block1,2, X. Wu1, P. Zhong1, G. Li1, T. Wang1, J.S. Hong1 & B.Veronesi.2
    1The Laboratory of Pharmacology and Chemistry, NIEHS, RTP, NC and 2 National Health and Envi...

  2. Prostaglandin E2 Receptor Subtype 2 Regulation of Scavenger Receptor CD36 Modulates Microglial Aβ42 Phagocytosis

    PubMed Central

    Li, Xianwu; Melief, Erica; Postupna, Nadia; Montine, Kathleen S.; Keene, C. Dirk; Montine, Thomas J.

    2016-01-01

    Recent studies underline the potential relevance of microglial innate immune activation in Alzheimer disease. Primary mouse microglia that lack prostaglandin E2 receptor subtype 2 (EP2) show decreased innate immune-mediated neurotoxicity and increased amyloid β (Aβ) peptide phagocytosis, features that were replicated in vivo. Here, we tested the hypothesis that scavenger receptor CD36 is an effector of EP2-regulated Aβ phagocytosis. CD36 expression was 143-fold greater in mouse primary microglia than in primary astrocytes. Three different means of suppressing EP2 signaling increased and an agonist of EP2 decreased CD36 expression in primary wild-type microglia. Activation of Toll-like receptor (TLR) 3, TLR4, and TLR7, but not TLR2 or TLR9, reduced primary microglial CD36 transcription and cell surface CD36 protein and reduced Aβ42 phagocytosis as well. At each step, the effects of innate immune activation on CD36 were reversed by at least 50% by an EP2 antagonist, and this partial rescue of microglia Aβ42 phagocytosis was largely mediated by CD36 activity. Finally, we showed in hippocampus of wild-type mice that innate immune activation suppressed CD36 expression by an EP2-dependent mechanism. Taken together with results of others that found brain clearance of Aβ peptides and behavioral improvements mediated by CD36 in mice, regulation of CD36-mediated Aβ phagocytosis by suppression of EP2 signaling may provide a new approach to suppressing some aspects of Alzheimer disease pathogenesis. PMID:25452117

  3. Anti-inflammatory effects and antioxidant activity of dihydroasparagusic acid in lipopolysaccharide-activated microglial cells.

    PubMed

    Salemme, Adele; Togna, Anna Rita; Mastrofrancesco, Arianna; Cammisotto, Vittoria; Ottaviani, Monica; Bianco, Armandodoriano; Venditti, Alessandro

    2016-01-01

    The activation of microglia and subsequent release of toxic pro-inflammatory factors are crucially associated with neurodegenerative disease, characterized by increased oxidative stress and neuroinflammation, including Alzheimer and Parkinson diseases and multiple sclerosis. Dihydroasparagusic acid is the reduced form of asparagusic acid, a sulfur-containing flavor component produced by Asparagus plants. It has two thiolic functions able to coordinate the metal ions, and a carboxylic moiety, a polar function, which may enhance excretion of the complexes. Thiol functions are also present in several biomolecules with important physiological antioxidant role as glutathione. The aim of this study is to evaluate the anti-inflammatory and antioxidant potential effect of dihydroasparagusic acid on microglial activation in an in vitro model of neuroinflammation. We have used lipopolysaccharide to induce an inflammatory response in primary rat microglial cultures. Our results suggest that dihydroasparagusic acid significantly prevented lipopolysaccharide-induced production of pro-inflammatory and neurotoxic mediators such as nitric oxide, tumor necrosis factor-α, prostaglandin E2, as well as inducible nitric oxide synthase and cyclooxygenase-2 protein expression and lipoxygenase activity in microglia cells. Moreover it effectively suppressed the level of reactive oxygen species and affected lipopolysaccharide-stimulated activation of mitogen activated protein kinase, including p38, and nuclear factor-kB pathway. These results suggest that dihydroasparagusic acid's neuroprotective properties may be due to its ability to dampen induction of microglial activation. It is a compound that can effectively inhibit inflammatory and oxidative processes that are important factors of the etiopathogenesis of neurodegenerative diseases. PMID:26592472

  4. Methamphetamine-induced neurotoxicity and microglial activation are not mediated by fractalkine receptor signaling

    PubMed Central

    Thomas, David M.; Francescutti-Verbeem, Dina M.; Kuhn, Donald M.

    2009-01-01

    Methamphetamine (METH) damages dopamine (DA) nerve endings by a process that has been linked to microglial activation but the signaling pathways that mediate this response have not yet been delineated. Cardona et al. [Nat. Neurosci. 9 (2006), 917] recently identified the microglial-specific fractalkine receptor (CX3CR1) as an important mediator of MPTP-induced neurodegeneration of DA neurons. Because the CNS damage caused by METH and MPTP is highly selective for the DA neuronal system in mouse models of neurotoxicity, we hypothesized that the CX3CR1 plays a role in METH-induced neurotoxicity and microglial activation. Mice in which the CX3CR1 gene has been deleted and replaced with a cDNA encoding enhanced green fluorescent protein (eGFP) were treated with METH and examined for striatal neurotoxicity. METH depleted DA, caused microglial activation, and increased body temperature in CX3CR1 knockout mice to the same extent and over the same time course seen in wild-type controls. The effects of METH in CX3CR1 knockout mice were not gender-dependent and did not extend beyond the striatum. Striatal microglia expressing eGFP constitutively show morphological changes after METH that are characteristic of activation. This response was restricted to the striatum and contrasted sharply with unresponsive eGFP-microglia in surrounding brain areas that are not damaged by METH. We conclude from these studies that CX3CR1 signaling does not modulate METH neurotoxicity or microglial activation. Furthermore, it appears that striatal-resident microglia respond to METH with an activation cascade and then return to a surveying state without undergoing apoptosis or migration. PMID:18410508

  5. Activation of mitochondrial transient receptor potential vanilloid 1 channel contributes to microglial migration.

    PubMed

    Miyake, Takahito; Shirakawa, Hisashi; Nakagawa, Takayuki; Kaneko, Shuji

    2015-10-01

    Microglia, the resident immune cells in the brain, survey the environment of the healthy brain. Microglial migration is essential for many physiological and pathophysiological processes. Although microglia express some members of the transient receptor potential (TRP) channel family, there is little knowledge regarding the physiological roles of TRP channels in microglia. Here, we explored the role of TRP vanilloid 1 (TRPV1), a channel opened by capsaicin, heat, protons, and endovanilloids, in microglia. We found that application of capsaicin induced concentration-dependent migration in microglia derived from wild-type mice but not in those derived from TRPV1 knockout (TRPV1-KO) mice. Capsaicin-induced microglial migration was significantly inhibited by co-application of the TRPV1 blocker SB366791 and the Ca(2+) chelator BAPTA-AM. Using RT-PCR and immunocytochemistry, we validated that TRPV1 was expressed in microglia. Electrophysiological recording, intracellular Ca(2+) imaging, and immunocytochemistry indicated that TRPV1 was localized primarily in intracellular organelles. Treatment with capsaicin induced an increase in intramitochondrial Ca(2+) concentrations and mitochondrial depolarization. Furthermore, microglia derived from TRPV1-KO mice showed delayed Ca(2+) efflux compared with microglia derived from wild-type mice. Capsaicin-induced microglial migration was inhibited by membrane-permeable antioxidants and MAPK inhibitors, suggesting that mitochondrial TRPV1 activation induced Ca(2+) -dependent production of ROS followed by MAPK activation, which correlated with an augmented migration of microglia. Moreover, a mixture of three endovanilloids augmented microglial migration via TRPV1 activation. Together, these results indicate that mitochondrial TRPV1 plays an important role in inducing microglial migration. Activation of TRPV1 triggers an increase in intramitochondrial Ca(2+) concentration and following depolarization of mitochondria, which results in mt

  6. Blueberry Supplementation Attenuates Microglial Activation in Hippocampal Intraocular Grafts to aged hosts

    PubMed Central

    Willis, Lauren M.; Freeman, Linnea; Bickford, Paula C.; Quintero, E. Matthew; Umphlet, Claudia D.; Moore, Alfred B.; Goetzl, Laura; Granholm, Ann-Charlotte

    2010-01-01

    Transplantation of central nervous tissue has been proposed as a therapeutic intervention for age-related neurodegenerative diseases and stroke. However, survival of embryonic neuronal cells is hampered by detrimental factors in the aged host brain such as circulating inflammatory cytokines and oxidative stress. We have previously found that supplementation with 2% blueberry in the diet increases graft growth and neuronal survival in intraocular hippocampal grafts to aged hosts. In the present study we explored possible biochemical mechanisms for this increased survival, and we here report decreased microglial activation and astrogliosis in intraocular hippocampal grafts to middle-aged hosts fed a 2% blueberry diet. Markers for astrocytes and for activated microglial cells were both decreased long-term after grafting to blueberry-treated hosts compared to age-matched rats on a control diet. Similar findings were obtained in the host brain, with a reduction in OX-6 immunoreactive microglial cells in the hippocampus of those recipients treated with blueberry. In addition, immunoreactivity for the pro-inflammatory cytokine IL-6 was found to be significantly attenuated in intraocular grafts by the 2% blueberry diet. These studies demonstrate direct effects of blueberry upon microglial activation both during isolated conditions and in the aged host brain and suggest that this nutraceutical can attenuate age-induced inflammation. PMID:20014277

  7. Targeting Microglial Activation in Stroke Therapy: Pharmacological Tools and Gender Effects

    PubMed Central

    Chen, Y.; Won, S.J.; Xu, Y.; Swanson, R.A.

    2014-01-01

    Ischemic stroke is caused by critical reductions in blood flow to brain or spinal cord. Microglia are the resident immune cells of the central nervous system, and they respond to stroke by assuming an activated phenotype that releases cytotoxic cytokines, reactive oxygen species, proteases, and other factors. This acute, innate immune response may be teleologically adapted to limit infection, but in stroke this response can exacerbate injury by further damaging or killing nearby neurons and other cell types, and by recruiting infiltration of circulating cytotoxic immune cells. The microglial response requires hours to days to fully develop, and this time interval presents a clinically accessible time window for initiating therapy. Because of redundancy in cytotoxic microglial responses, the most effective therapeutic approach may be to target the global gene expression changes involved in microglial activation. Several classes of drugs can do this, including histone deacetylase inhibitors, minocycline and other PARP inhibitors, corticosteroids, and inhibitors of TNFα and scavenger receptor signaling. Here we review the pre-clinical studies in which these drugs have been used to suppress microglial activation after stroke. We also review recent advances in the understanding of sex differences in the CNS inflammatory response, as these differences are likely to influence the efficacy of drugs targeting post-stroke brain inflammation. PMID:24372213

  8. Doxycycline Suppresses Microglial Activation by Inhibiting the p38 MAPK and NF-kB Signaling Pathways.

    PubMed

    Santa-Cecília, Flávia V; Socias, Benjamin; Ouidja, Mohand O; Sepulveda-Diaz, Julia E; Acuña, Leonardo; Silva, Rangel L; Michel, Patrick P; Del-Bel, Elaine; Cunha, Thiago M; Raisman-Vozari, Rita

    2016-05-01

    In neurodegenerative diseases, the inflammatory response is mediated by activated glial cells, mainly microglia, which are the resident immune cells of the central nervous system. Activated microglial cells release proinflammatory mediators and neurotoxic factors that are suspected to cause or exacerbate these diseases. We recently demonstrated that doxycycline protects substantia nigra dopaminergic neurons in an animal model of Parkinson's disease. This effect was associated with a reduction of microglial cell activation, which suggests that doxycycline may operate primarily as an anti-inflammatory drug. In the present study, we assessed the anti-inflammatory potential of doxycycline using lipopolysaccharide (LPS)-activated primary microglial cells in culture as a model of neuroinflammation. Doxycycline attenuated the expression of key activation markers in LPS-treated microglial cultures in a concentration-dependent manner. More specifically, doxycycline treatment lowered the expression of the microglial activation marker IBA-1 as well as the production of ROS, NO, and proinflammatory cytokines (TNF-α and IL-1β). In primary microglial cells, we also found that doxycycline inhibits LPS-induced p38 MAP kinase phosphorylation and NF-kB nuclear translocation. The present results indicate that the effect of doxycycline on LPS-induced microglial activation probably occurs via the modulation of p38 MAP kinase and NF-kB signaling pathways. These results support the idea that doxycycline may be useful in preventing or slowing the progression of PD and other neurodegenerative diseases that exhibit altered glia function. PMID:26745968

  9. Low-dose methotrexate reduces peripheral nerve injury-evoked spinal microglial activation and neuropathic pain behavior in rats

    PubMed Central

    Scholz, Joachim; Abele, Andrea; Marian, Claudiu; Häussler, Annett; Herbert, Teri A.; Woolf, Clifford J.; Tegeder, Irmgard

    2008-01-01

    Peripheral nerve injuries that provoke neuropathic pain are associated with microglial activation in the spinal cord. We have investigated the characteristics of spinal microglial activation in three distinct models of peripheral neuropathic pain: spared nerve injury (SNI), chronic constriction injury, and spinal nerve ligation. In all models, dense clusters of cells immunoreactive for the microglial marker CD11b formed in the ipsilateral dorsal horn 7 days after injury. Microglial expression of ionized calcium binding adapter molecule 1 (Iba1) increased by up to 40% and phosphorylation of p38 mitogen-activated protein kinase, a marker of microglial activity, by 45%. Expression of the lysosomal ED1-antigen indicated phagocytic activity of the cells. Unlike the peripheral nerve lesions, rhizotomy produced only a weak microglial reaction within the spinal gray matter but a strong activation of microglia and phagocytes in the dorsal funiculus at lumbar and thoracic spinal cord levels. This suggests that although degeneration of central terminals is sufficient to elicit microglial activation, it does not account for the inflammatory response in the dorsal horn after peripheral nerve injury. Early intrathecal treatment with low-dose methotrexate, beginning at the time of injury, decreased microglial activation, reduced p38 phosphorylation, and attenuated pain-like behavior after SNI. In contrast, systemic or intrathecal delivery of the glucocorticoid dexamethasone did not inhibit the activation of microglia or reduce pain-like behavior. We confirm that microglial activation is crucial for the development of pain after nerve injury, and demonstrate that suppression of this cellular immune response is a promising approach for preventing neuropathic pain. PMID:18215468

  10. Radiation-Induced c-Jun Activation Depends on MEK1-ERK1/2 Signaling Pathway in Microglial Cells

    PubMed Central

    Deng, Zhiyong; Sui, Guangchao; Rosa, Paulo Mottin; Zhao, Weiling

    2012-01-01

    Radiation-induced normal brain injury is associated with acute and/or chronic inflammatory responses, and has been a major concern in radiotherapy. Recent studies suggest that microglial activation is a potential contributor to chronic inflammatory responses following irradiation; however, the molecular mechanism underlying the response of microglia to radiation is poorly understood. c-Jun, a component of AP-1 transcription factors, potentially regulates neural cell death and neuroinflammation. We observed a rapid increase in phosphorylation of N-terminal c-Jun (on serine 63 and 73) and MAPK kinases ERK1/2, but not JNKs, in irradiated murine microglial BV2 cells. Radiation-induced c-Jun phosphorylation is dependent on the canonical MEK-ERK signaling pathway and required for both ERK1 and ERK2 function. ERK1/2 directly interact with c-Jun in vitro and in cells; meanwhile, the JNK binding domain on c-Jun is not required for its interaction with ERK kinases. Radiation-induced reactive oxygen species (ROS) potentially contribute to c-Jun phosphorylation through activating the ERK pathway. Radiation stimulates c-Jun transcriptional activity and upregulates c-Jun-regulated proinflammatory genes, such as tumor necrosis factor-α, interleukin-1β, and cyclooxygenase-2. Pharmacologic blockade of the ERK signaling pathway interferes with c-Jun activity and inhibits radiation-stimulated expression of c-Jun target genes. Overall, our study reveals that the MEK-ERK1/2 signaling pathway, but not the JNK pathway, contributes to the c-Jun-dependent microglial inflammatory response following irradiation. PMID:22606284

  11. Differential Effects of Homotypic vs. Heterotypic Chronic Stress Regimens on Microglial Activation in the Prefrontal Cortex

    PubMed Central

    Kopp, Brittany L.; Wick, Dayna; Herman, James P.

    2013-01-01

    Stress pathology is associated with hypothalamic-pituitary-adrenal (HPA) axis dysregulation and aberrant glucocorticoid responses. Recent studies indicate increases in prefrontal cortical ionized calcium-binding adapter molecule 1 (Iba-1) staining following repeated restraint, reflecting increased microglial densities. Our experiments tested expression of Iba-1 staining in the prelimbic cortex (PL), infralimbic cortex (IL) and the hypothalamic paraventricular nucleus (PVN) following two-week exposure to repeated restraint (RR) and chronic variable stress (CVS), representing homotypic and heterotypic regimens, respectively. Unstressed animals served as controls. We specifically examined Iba-1 immunofluorescence in layers 2 and 3 versus layers 5 and 6 of the PL and IL, using both cell number and field staining density. Iba-1 field staining density was increased in both the PL and IL following RR in comparison to controls. This effect was not observed following CVS. Furthermore, PVN Iba-1 immunoreactivity was not affected by either stress regimen. Cell number did not vary within any brain areas or across stress exposures. Changes in microglial field density did not reflect changes in vascular density. Increases in PL and IL microglial density indicate selective microglial activation during RR, perhaps due to mild stress in the context of limited elevations in anti-inflammatory glucocorticoid actions. Supported by NIH grants [MH049698 and MH069860]. PMID:23707717

  12. Identification of a novel dehydroergosterol enhancing microglial anti-inflammatory activity in a dairy product fermented with Penicillium candidum.

    PubMed

    Ano, Yasuhisa; Kutsukake, Toshiko; Hoshi, Ayaka; Yoshida, Aruto; Nakayama, Hiroyuki

    2015-01-01

    Despite the ever-increasing number of dementia patients worldwide, fundamental therapeutic approaches to treat this disease remain to be established. Preventive approaches such as diet, exercise and learning attract attention. Several epidemiological studies suggest that ingestion of fermented dairy products prevents cognitive decline in the elderly. These reports indicate that specific ingredients in the fermented dairy products elicit an anti-inflammatory or anti-oxidative activity that facilitates neuroprotection. The responsible components remain to be investigated. A number of studies have shown that inflammation caused by microglia is closely related to exaggeration of the pathology and cognitive decline seen in the elderly. Many researchers have proposed that controlling microglial activities could be effective in preventing and possibly curing dementia. In the present study, to elucidate specific compounds that regulate microglial activity from dairy products, repeated purification by HPLC, combined with evaluation using primary microglia, facilitated the identification of dehydroergosterol (DHE) as a novel component of the extract that enhances microglial anti-inflammatory activity. DHE contains three conjugated double bonds in a steroid ring system and is an analogue of ergosterol. Despite their related chemical structures, the anti-inflammatory activity of DHE is markedly stronger than that of ergosterol. P. candidum for camembert cheese produces DHE, but P. Roqueforti for blue cheese and Aspergillus do not. DHE also induces CD11b-positive microglia cells into CD206-positive M2 type microglia. Neurotoxicity and neuronal cell death induced by excessively activated microglia is suppressed by treatment with DHE. Thus, this is the first report to demonstrate that DHE, identified as a responsible compound in dairy products, can induce microglia into a preferable phenotype for our brain environment and can be safely introduced into the body by consumption of

  13. Identification of a Novel Dehydroergosterol Enhancing Microglial Anti-Inflammatory Activity in a Dairy Product Fermented with Penicillium candidum

    PubMed Central

    Ano, Yasuhisa; Kutsukake, Toshiko; Hoshi, Ayaka; Yoshida, Aruto; Nakayama, Hiroyuki

    2015-01-01

    Despite the ever-increasing number of dementia patients worldwide, fundamental therapeutic approaches to treat this disease remain to be established. Preventive approaches such as diet, exercise and learning attract attention. Several epidemiological studies suggest that ingestion of fermented dairy products prevents cognitive decline in the elderly. These reports indicate that specific ingredients in the fermented dairy products elicit an anti-inflammatory or anti-oxidative activity that facilitates neuroprotection. The responsible components remain to be investigated. A number of studies have shown that inflammation caused by microglia is closely related to exaggeration of the pathology and cognitive decline seen in the elderly. Many researchers have proposed that controlling microglial activities could be effective in preventing and possibly curing dementia. In the present study, to elucidate specific compounds that regulate microglial activity from dairy products, repeated purification by HPLC, combined with evaluation using primary microglia, facilitated the identification of dehydroergosterol (DHE) as a novel component of the extract that enhances microglial anti-inflammatory activity. DHE contains three conjugated double bonds in a steroid ring system and is an analogue of ergosterol. Despite their related chemical structures, the anti-inflammatory activity of DHE is markedly stronger than that of ergosterol. P. candidum for camembert cheese produces DHE, but P. Roqueforti for blue cheese and Aspergillus do not. DHE also induces CD11b-positive microglia cells into CD206-positive M2 type microglia. Neurotoxicity and neuronal cell death induced by excessively activated microglia is suppressed by treatment with DHE. Thus, this is the first report to demonstrate that DHE, identified as a responsible compound in dairy products, can induce microglia into a preferable phenotype for our brain environment and can be safely introduced into the body by consumption of

  14. 1950 MHz IMT-2000 field does not activate microglial cells in vitro.

    PubMed

    Hirose, Hideki; Sasaki, Atsushi; Ishii, Nana; Sekijima, Masaru; Iyama, Takahiro; Nojima, Toshio; Ugawa, Yoshikazu

    2010-02-01

    Given the widespread use of the cellular phone today, investigation of potential biological effects of radiofrequency (RF) fields has become increasingly important. In particular, much research has been conducted on RF effects on brain function. To examine any biological effects on the central nervous system (CNS) induced by 1950 MHz modulation signals, which are controlled by the International Mobile Telecommunication-2000 (IMT-2000) cellular system, we investigated the effect of RF fields on microglial cells in the brain. We assessed functional changes in microglial cells by examining changes in immune reaction-related molecule expression and cytokine production after exposure to a 1950 MHz Wideband Code Division Multiple Access (W-CDMA) RF field, at specific absorption rates (SARs) of 0.2, 0.8, and 2.0 W/kg. Primary microglial cell cultures prepared from neonatal rats were subjected to an RF or sham field for 2 h. Assay samples obtained 24 and 72 h after exposure were processed in a blind manner. Results showed that the percentage of cells positive for major histocompatibility complex (MHC) class II, which is the most common marker for activated microglial cells, was similar between cells exposed to W-CDMA radiation and sham-exposed controls. No statistically significant differences were observed between any of the RF field exposure groups and the sham-exposed controls in percentage of MHC class II positive cells. Further, no remarkable differences in the production of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) were observed between the test groups exposed to W-CDMA signal and the sham-exposed negative controls. These findings suggest that exposure to RF fields up to 2 W/kg does not activate microglial cells in vitro. PMID:19650078

  15. Recognition of Betaine as an Inhibitor of Lipopolysaccharide-Induced Nitric Oxide Production in Activated Microglial Cells

    PubMed Central

    Amiraslani, Banafsheh; Sabouni, Farzaneh; Abbasi, Shahsanam; Nazem, Habiballah; Sabet, Mohammadsadegh

    2012-01-01

    Background: Neuroinflammation, as a major outcome of microglia activation, is an important factor for progression of neurodegenerative disorders including Alzheimer's disease and Parkinson's disease. Microglial cells, as the first-line defense in the central nervous system, act as a source of neurotoxic factors such as nitric oxide (NO), a free radical which is involved in neuronal cell death. The aim of this study was to inhibit production of NO in activated microglial cells in order to decrease neurological damages that threat the central nervous system. Methods: An in vitro model of a newborn rat brain cell culture was used to examine the effect of betaine on the release of NO induced by lipopolysaccharide (LPS). Briefly, primary microglial cells were stimulated by LPS and after 2 minutes, they were treated by different concentrations of betaine. The production of NO was assessed by the Griess assay while cell viability was determined by the MTT assay. Results: Our investigations indicated that LPS-induced NO release was attenuated by betaine, suggesting that this compound might inhibit NO release. The effects of betaine on NO production in activated microglial cells after 24 h were "dose-dependent". It means that microglial cells which were treated with higher concentrations of betaine, released lower amounts of NO. Also our observations showed that betaine compound has no toxic effect on microglial cells. Conclusion: Betaine has an inhibitory effect on NO release in activated microglial cells and may be an effective therapeutic component to control neurological disorders. PMID:22801281

  16. NADPH Oxidase- and Mitochondria-derived Reactive Oxygen Species in Proinflammatory Microglial Activation: A Bipartisan Affair?

    PubMed Central

    Bordt, Evan A.; Polster, Brian M.

    2014-01-01

    Microglia are the resident immune cells of the brain and play major roles in central nervous system development, maintenance, and disease. Brain insults cause microglia to proliferate, migrate, and transform into one or more activated states. Classical M1 activation triggers the production of proinflammatory factors such as tumor necrosis factor- α (TNF-α), interleukin-1β (IL-1β), nitric oxide (NO), and reactive oxygen species which, in excess, can exacerbate brain injury. The mechanisms underlying microglial activation are not fully understood, yet reactive oxygen species are increasingly implicated as mediators of microglial activation. In this review, we highlight studies linking reactive oxygen species, in particular hydrogen peroxide derived from NADPH oxidase-generated superoxide, to the classical activation of microglia. In addition, we critically evaluate controversial evidence suggesting a specific role for mitochondrial reactive oxygen species in the activation of the NLRP3 inflammasome, a multiprotein complex that mediates the production of IL-1β and IL-18. Finally, the limitations of common techniques used to implicate mitochondrial ROS in microglial and inflammasome activation, such as the use of the mitochondrially-targeted ROS indicator MitoSOX and the mitochondrially-targeted antioxidant MitoTEMPO, are also discussed. PMID:25091898

  17. Mechanisms and Potential Therapeutic Applications of Microglial Activation after Brain Injury

    PubMed Central

    Kim, Jong Youl; Kim, Nuri; Yenari, Midori A.

    2014-01-01

    As the resident immune cells of the central nervous system, microglia rapidly respond to brain insults, including stroke and traumatic brain injury. Microglial activation plays a major role in neuronal cell damage and death by releasing a variety of inflammatory and neurotoxic mediators. Their activation is an early response that may exacerbate brain injury and many other stressors, especially in the acute stages, but are also essential to brain recovery and repair. The full range of microglial activities is still not completely understood, but there is accumulating knowledge about their role following brain injury. We review recent progress related to the deleterious and beneficial effects of microglia in the setting of acute neurological insults, and the current literature surrounding pharmacological interventions for intervention. PMID:25475659

  18. c-Src function is necessary and sufficient for triggering microglial cell activation.

    PubMed

    Socodato, Renato; Portugal, Camila C; Domith, Ivan; Oliveira, Nádia A; Coreixas, Vivian S M; Loiola, Erick C; Martins, Tânia; Santiago, Ana Raquel; Paes-de-Carvalho, Roberto; Ambrósio, António F; Relvas, João B

    2015-03-01

    Microglial cells are the resident macrophages of the central nervous system. Their function is essential for neuronal tissue homeostasis. After inflammatory stimuli, microglial cells become activated changing from a resting and highly ramified cell shape to an amoeboid-like morphology. These morphological changes are associated with the release of proinflammatory cytokines and glutamate, as well as with high phagocytic activity. The acquisition of such phenotype has been associated with activation of cytoplasmic tyrosine kinases, including those of the Src family (SFKs). In this study, using both in vivo and in vitro inflammation models coupled to FRET-based time-lapse microscopy, lentiviruses-mediated shRNA delivery and genetic gain-of-function experiments, we demonstrate that among SFKs c-Src function is necessary and sufficient for triggering microglia proinflammatory signature, glutamate release, microglia-induced neuronal loss, and phagocytosis. c-Src inhibition in retinal neuroinflammation experimental paradigms consisting of intravitreal injection of LPS or ischemia-reperfusion injury significantly reduced microglia activation changing their morphology to a more resting phenotype and prevented neuronal apoptosis. Our data demonstrate an essential role for c-Src in microglial cell activation. PMID:25421817

  19. Glioma-secreted soluble factors stimulate microglial activation: The role of interleukin-1β and tumor necrosis factor-α.

    PubMed

    Hwang, Ji-Sun; Jung, Eun-Hye; Kwon, Mi-Youn; Han, Inn-Oc

    2016-09-15

    We aimed to elucidate the effect of soluble factors secreted by glioma on microglial activation. Conditioned medium (CM) from glioma cells, CRT-MG and C6, significantly induced nitric oxide (NO) production and stimulated the mRNA expression of inducible NO synthase (iNOS), interleukin (IL)-1beta, IL-6, tumor necrosis factor-alpha (TNF-α) and cyclooxygenase 2 (COX-2) in BV2 cells. Glioma CM stimulated p38 mitogen-activated protein kinase (MAPK) phosphorylation, and a p38 MAPK inhibitor, SB203580, suppressed CM-induced NO production in BV2 cells. In addition, CM stimulated nuclear factor-kappaB (NF-κB) DNA binding and transcriptional activity, which was repressed by SB203580. Gliomas displayed higher mRNA expression and release of TNF-α and IL-1β than primary astrocyte cells. Neutralization of TNF-α and IL-1β in C6-CM using a neutralizing antibody inhibited NO/iNOS expression in BV-2 cells. These results indicate potential contribution of diffusible tumor-derived factors to regulate microglial activation and subsequent tumor microenvironment. PMID:27609291

  20. Insensitivity of astrocytes to interleukin 10 signaling following peripheral immune challenge results in prolonged microglial activation in the aged brain.

    PubMed

    Norden, Diana M; Trojanowski, Paige J; Walker, Frederick R; Godbout, Jonathan P

    2016-08-01

    Immune-activated microglia from aged mice produce exaggerated levels of cytokines. Despite high levels of microglial interleukin (IL)-10 in the aged brain, neuroinflammation was prolonged and associated with depressive-like deficits. Because astrocytes respond to IL-10 and, in turn, attenuate microglial activation, we investigated if astrocyte-mediated resolution of microglial activation was impaired with age. Here, aged astrocytes had a dysfunctional profile with higher glial fibrillary acidic protein, lower glutamate transporter expression, and significant cytoskeletal re-arrangement. Moreover, aged astrocytes had reduced expression of growth factors and IL-10 receptor-1 (IL-10R1). After in vivo lipopolysaccharide immune challenge, aged astrocytes had a molecular signature associated with reduced responsiveness to IL-10. This IL-10 insensitivity of aged astrocytes resulted in a failure to induce IL-10R1 and transforming growth factor β and resolve microglial activation. In addition, adult astrocytes reduced microglial activation when co-cultured ex vivo, whereas aged astrocytes did not. Consistent with the aging studies, IL-10R(KO) astrocytes did not augment transforming growth factor β after immune challenge and failed to resolve microglial activation. Collectively, a major cytokine-regulatory loop between activated microglia and astrocytes is impaired in the aged brain. PMID:27318131

  1. Levo-Tetrahydropalmatine Attenuates Bone Cancer Pain by Inhibiting Microglial Cells Activation

    PubMed Central

    Zhang, Mao-yin; Liu, Yue-peng; Zhang, Lian-yi; Yue, Dong-mei; Qi, Dun-yi; Liu, Gong-jian; Liu, Su

    2015-01-01

    Objective. The present study is to investigate the analgesic roles of L-THP in rats with bone cancer pain caused by tumor cell implantation (TCI). Methods. Thermal hyperalgesia and mechanical allodynia were measured at different time points before and after operation. L-THP (20, 40, and 60 mg/kg) were administrated intragastrically at early phase of postoperation (before pain appearance) and later phase of postoperation (after pain appearance), respectively. The concentrations of TNF-α, IL-1β, and IL-18 in spinal cord were measured by enzyme-linked immunosorbent assay. Western blot was used to test the activation of astrocytes and microglial cells in spinal cord after TCI treatment. Results. TCI treatment induced significant thermal hyperalgesia and mechanical allodynia. Administration of L-THP at high doses significantly prevented and/or reversed bone cancer-related pain behaviors. Besides, TCI-induced activation of microglial cells and the increased levels of TNF-α and IL-18 were inhibited by L-THP administration. However, L-THP failed to affect TCI-induced astrocytes activation and IL-1β increase. Conclusion. This study suggests the possible clinical utility of L-THP in the treatment of bone cancer pain. The analgesic effects of L-THP on bone cancer pain maybe underlying the inhibition of microglial cells activation and proinflammatory cytokines increase. PMID:26819501

  2. Papaverine inhibits lipopolysaccharide-induced microglial activation by suppressing NF-κB signaling pathway

    PubMed Central

    Dang, Yalong; Mu, Yalin; Wang, Kun; Xu, Ke; Yang, Jing; Zhu, Yu; Luo, Bin

    2016-01-01

    Objective To investigate the effects of papaverine (PAP) on lipopolysaccharide (LPS)-induced microglial activation and its possible mechanisms. Materials and methods BV2 microglial cells were first pretreated with PAP (0, 0.4, 2, 10, and 50 μg/mL) and then received LPS stimulation. Transcription and production of proinflammatory factors (IL1β, TNFα, iNOS, and COX-2) were used to evaluate microglial activation. The transcriptional changes undergone by M1/M2a/M2b markers were used to evaluate phenotype transformation of BV2 cells. Immunofluorescent staining and Western blot were used to detect the location and expression of P65 and p-IKK in the presence or absence of PAP pretreatment. Results Pretreatment with PAP significantly inhibited the expression of IL1β and TNFα, and suppressed the transcription of M1/M2b markers Il1rn, Socs3, Nos2 and Ptgs2, but upregulated the transcription of M2a markers (Arg1 and Mrc1) in a dose-dependent manner. In addition, PAP pretreatment significantly decreased the expression of p-IKK and inhibited the nuclear translocation of P65 after LPS stimulation. Conclusion PAP not only suppressed the LPS-induced microglial activity by inhibiting transcription/production of proinflammatory factors, but also promoted the transformation of activated BV2 cells from cytotoxic phenotypes (M1/M2b) to a neuroprotective phenotype (M2a). These effects were probably mediated by NF-κB signaling pathway. Thus, it would be a promising candidate for the treatment of neurodegenerative diseases. PMID:27013863

  3. Treatment with polyamine oxidase inhibitor reduces microglial activation and limits vascular injury in ischemic retinopathy.

    PubMed

    Patel, C; Xu, Z; Shosha, E; Xing, J; Lucas, R; Caldwell, R W; Caldwell, R B; Narayanan, S P

    2016-09-01

    Retinal vascular injury is a major cause of vision impairment in ischemic retinopathies. Insults such as hyperoxia, oxidative stress and inflammation contribute to this pathology. Previously, we showed that hyperoxia-induced retinal neurodegeneration is associated with increased polyamine oxidation. Here, we are studying the involvement of polyamine oxidases in hyperoxia-induced injury and death of retinal vascular endothelial cells. New-born C57BL6/J mice were exposed to hyperoxia (70% O2) from postnatal day (P) 7 to 12 and were treated with the polyamine oxidase inhibitor MDL 72527 or vehicle starting at P6. Mice were sacrificed after different durations of hyperoxia and their retinas were analyzed to determine the effects on vascular injury, microglial cell activation, and inflammatory cytokine profiling. The results of this analysis showed that MDL 72527 treatment significantly reduced hyperoxia-induced retinal vascular injury and enhanced vascular sprouting as compared with the vehicle controls. These protective effects were correlated with significant decreases in microglial activation as well as levels of inflammatory cytokines and chemokines. In order to model the effects of polyamine oxidation in causing microglial activation in vitro, studies were performed using rat brain microvascular endothelial cells treated with conditioned-medium from rat retinal microglia stimulated with hydrogen peroxide. Conditioned-medium from activated microglial cultures induced cell stress signals and cell death in microvascular endothelial cells. These studies demonstrate the involvement of polyamine oxidases in hyperoxia-induced retinal vascular injury and retinal inflammation in ischemic retinopathy, through mechanisms involving cross-talk between endothelial cells and resident retinal microglia. PMID:27239699

  4. Acupuncture inhibits microglial activation and inflammatory events in the MPTP-induced mouse model.

    PubMed

    Kang, Jun Mo; Park, Hi Joon; Choi, Yeong Gon; Choe, Il Hwan; Park, Jae Hyun; Kim, Yong Sik; Lim, Sabina

    2007-02-01

    Using a mouse model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD), this study investigated on the neuroprotective effects of acupuncture by examining whether acupuncture contributed to inhibiting microglial activation and inflammatory events. C57BL/6 mice were treated with MPTP (30 mg/kg, i.p.) for 5 consecutive days. Acupuncture was then applied to acupoints Yanglingquan (GB34) and Taichong (LR3) starting 2 h after the first MPTP administration and then at 48 h intervals until the mice were sacrificed for analyses at 1, 3, and 7 days after the last MPTP injection. These experiments demonstrated that acupuncture inhibited the decreased of the tyrosine hydroxylase (TH) immunoreactivity (IR) and generated a neuroprotective effects in the striatum (ST) and the substantia nigra (SN) on days 1, 3, and 7 post-MPTP injections. Acupuncture attenuated the increase of macrophage antigen complex-1 (MAC-1), a marker of microglial activation, at 1 and 3 days and reduced the increases in cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression on days 1, 3, and 7. In MPTP group, striatal dopamine (DA) was measured by 46% at 7 days, whereas DA in the acupuncture group was 78%. On the basis of these results, we suggest that acupuncture could be used as a neuroprotective intervention for the purpose of inhibiting microglial activation and inflammatory events in PD. PMID:17173870

  5. Cerium Oxide Nanoparticles Reduce Microglial Activation and Neurodegenerative Events in Light Damaged Retina

    PubMed Central

    Fiorani, Lavinia; Passacantando, Maurizio; Santucci, Sandro; Di Marco, Stefano; Bisti, Silvia; Maccarone, Rita

    2015-01-01

    The first target of any therapy for retinal neurodegeneration is to slow down the progression of the disease and to maintain visual function. Cerium oxide or ceria nanoparticles reduce oxidative stress, which is known to play a pivotal role in neurodegeneration. Our aim was to investigate whether cerium oxide nanoparticles were able to mitigate neurodegeneration including microglial activation and related inflammatory processes induced by exposure to high intensity light. Cerium oxide nanoparticles were injected intravitreally or intraveinously in albino Sprague-Dawley rats three weeks before exposing them to light damage of 1000 lux for 24 h. Electroretinographic recordings were performed a week after light damage. The progression of retinal degeneration was evaluated by measuring outer nuclear layer thickness and TUNEL staining to quantify photoreceptors death. Immunohistochemical analysis was used to evaluate retinal stress, neuroinflammatory cytokines and microglial activation. Only intravitreally injected ceria nanoparticles were detected at the level of photoreceptor outer segments 3 weeks after the light damage and electoretinographic recordings showed that ceria nanoparticles maintained visual response. Moreover, this treatment reduced neuronal death and “hot spot” extension preserving the outer nuclear layer morphology. It is noteworthy that in this work we demonstrated, for the first time, the ability of ceria nanoparticles to reduce microglial activation and their migration toward outer nuclear layer. All these evidences support ceria nanoparticles as a powerful therapeutic agent in retinal neurodegenerative processes. PMID:26469804

  6. Microglial p53 activation is detrimental to neuronal synapses during activation-induced inflammation: Implications for neurodegeneration.

    PubMed

    Jebelli, Joseph; Hooper, Claudie; Pocock, Jennifer M

    2014-11-01

    P53 is a tumour suppressor protein thought to be primarily involved in cancer biology, but recent evidence suggests it may also coordinate novel functions in the CNS, including mediation of pathways underlying neurodegenerative disease. In microglia, the resident immune cells of the brain, p53 activity can promote an activation-induced pro-inflammatory phenotype Jayadev et al. (2011) [1], as well as neurodegeneration Davenport et al. (2010) [2]. Synapse degeneration is one of the earliest pathological events in many chronic neurodegenerative diseases Conforti et al. (2007) and Clare et al. (2010) [3,4] and may be influenced by early microglial responses. Here we examined synaptic properties of neurons following modulation of p53 activity in rat microglia exposed to inflammatory stimuli. A significant reduction in the expression of the neuronal synaptic markers synaptophysin and drebrin, occurred following microglial activation and was seen prior to any visible signs of neuronal cell death, including neuronal cleaved caspase-3 activation. This synaptic marker loss together with microglial secretion of the inflammatory cytokines tumour necrosis factor α (TNF-α) and interleukin 1-β (IL-1β) was abolished by the removal of microglia or inhibition of microglial p53 activation. These results suggest that transcriptional-dependent p53 activities in microglia may drive a non-cell autonomous process of synaptic degeneration in neurons during neuroinflammatory degenerative diseases. PMID:25204787

  7. Microglial activation, recruitment and phagocytosis as linked phenomena in ferric oxide nanoparticle exposure.

    PubMed

    Wang, Yun; Wang, Bing; Zhu, Mo-Tao; Li, Ming; Wang, Hua-Jian; Wang, Meng; Ouyang, Hong; Chai, Zhi-Fang; Feng, Wei-Yue; Zhao, Yu-Liang

    2011-08-10

    Microglia as the resident macrophage-like cells in the central nervous system (CNS) play a pivotal role in the innate immune responses of CNS. Understanding the reactions of microglia cells to nanoparticle exposure is important in the exploration of neurobiology of nanoparticles. Here we provide a systemic mapping of microglia and the corresponding pathological changes in olfactory-transport related brain areas of mice with Fe(2)O(3)-nanoparticle intranasal treatment. We showed that intranasal exposure of Fe(2)O(3) nanoparticle could lead to pathological alteration in olfactory bulb, hippocampus and striatum, and caused microglial proliferation, activation and recruitment in these areas, especially in olfactory bulb. Further experiments with BV2 microglial cells showed the exposure to Fe(2)O(3) nanoparticles could induce cells proliferation, phagocytosis and generation of ROS and NO, but did not cause significant release of inflammatory factors, including IL-1β, IL-6 and TNF-α. Our results indicate that microglial activation may act as an alarm and defense system in the processes of the exogenous nanoparticles invading and storage in brain. PMID:21596115

  8. Longitudinal influence of microglial activation and amyloid on neuronal function in Alzheimer's disease.

    PubMed

    Fan, Zhen; Okello, Aren A; Brooks, David J; Edison, Paul

    2015-12-01

    Amyloid deposition, tangle formation, neuroinflammation and neuronal dysfunction are pathological processes involved in Alzheimer's disease. However, the relative role of these processes in driving disease progression is still unclear. The aim of this positron emission tomography study was to: (i) investigate longitudinal changes of microglial activation, amyloid and glucose metabolism; and (ii) assess the temporospatial relationship between these three processes in Alzheimer's disease. A group of eight patients with a diagnosis of Alzheimer's disease (66 ± 4.8 years) and 14 healthy controls (65 ± 5.5 years) underwent T1 and T2 magnetic resonance imaging, along with (11)C-(R)-PK11195, (11)C-Pittsburgh compound B and (18)F-fluorodeoxyglucose positron emission tomography scans for microglial activation, amyloid deposition and glucose metabolism. All patients were followed-up with repeated magnetic resonance imaging and three positron emission tomography scans after 16 months. Parametric maps were interrogated using region of interest analysis, Statistical Parametric Mapping, and between-group correlation analysis at voxel-level using Biological Parametric Mapping. At baseline, patients with Alzheimer's disease showed significantly increased microglial activation compared to the control subjects. During follow-up, for the first time, we found that while there is a progressive reduction of glucose metabolism, there was a longitudinal increase of microglial activation in the majority of the patients with Alzheimer's disease. Voxel-wise correlation analysis revealed that microglial activation in patients with Alzheimer's disease was positively correlated with amyloid deposition and inversely correlated with regional cerebral metabolic rate at voxel level over time. Even though one of the limitations of this study is the lack of longitudinal follow-up of healthy control subjects, this study demonstrates that there is persistent neuroinflammation throughout the Alzheimer

  9. MicroRNA 146a (miR-146a) is over-expressed during prion disease and modulates the innate immune response and the microglial activation state.

    PubMed

    Saba, Reuben; Gushue, Shantel; Huzarewich, Rhiannon L C H; Manguiat, Kathy; Medina, Sarah; Robertson, Catherine; Booth, Stephanie A

    2012-01-01

    Increasing evidence supports the involvement of microRNAs (miRNAs) in inflammatory and immune processes in prion neuropathogenesis. MiRNAs are small, non-coding RNA molecules which are emerging as key regulators of numerous cellular processes. We established miR-146a over-expression in prion-infected mouse brain tissues concurrent with the onset of prion deposition and appearance of activated microglia. Expression profiling of a variety of central nervous system derived cell-lines revealed that miR-146a is preferentially expressed in cells of microglial lineage. Prominent up-regulation of miR-146a was evident in the microglial cell lines BV-2 following TLR2 or TLR4 activation and also EOC 13.31 via TLR2 that reached a maximum 24-48 hours post-stimulation, concomitant with the return to basal levels of transcription of induced cytokines. Gain- and loss-of-function studies with miR-146a revealed a substantial deregulation of inflammatory response pathways in response to TLR2 stimulation. Significant transcriptional alterations in response to miR-146a perturbation included downstream mediators of the pro-inflammatory transcription factor, nuclear factor-kappa B (NF-κB) and the JAK-STAT signaling pathway. Microarray analysis also predicts a role for miR-146a regulation of morphological changes in microglial activation states as well as phagocytic mediators of the oxidative burst such as CYBA and NOS3. Based on our results, we propose a role for miR-146a as a potent modulator of microglial function by regulating the activation state during prion induced neurodegeneration. PMID:22363497

  10. Cannabidiol enhances microglial phagocytosis via transient receptor potential (TRP) channel activation

    PubMed Central

    Hassan, Samia; Eldeeb, Khalil; Millns, Paul J; Bennett, Andrew J; Alexander, Stephen P H; Kendall, David A

    2014-01-01

    Background and Purpose Microglial cells are important mediators of the immune response in the CNS. The phytocannabinoid, cannabidiol (CBD), has been shown to have central anti-inflammatory properties, and the purpose of the present study was to investigate the effects of CBD and other phytocannabinoids on microglial phagocytosis. Experimental Approach Phagocytosis was assessed by measuring ingestion of fluorescently labelled latex beads by cultured microglial cells. Drug effects were probed using single-cell Ca2+ imaging and expression of mediator proteins by immunoblotting and immunocytochemistry. Key Results CBD (10 μM) enhanced bead phagocytosis to 175 ± 7% control. Other phytocannabinoids, synthetic and endogenous cannabinoids were without effect. The enhancement was dependent upon Ca2+ influx and was abolished in the presence of EGTA, the Ca2+ channel inhibitor SKF96365, the transient receptor potential (TRP) channel blocker ruthenium red, and the TRPV1 antagonists capsazepine and AMG9810. CBD produced a sustained increase in intracellular Ca2+ concentration in BV-2 microglia and this was abolished by ruthenium red. CBD rapidly increased the expression of TRPV2 and TRPV1 proteins and caused a translocation of TRPV2 to the cell membrane. Wortmannin blocked CBD enhancement of BV-2 cell phagocytosis, suggesting that it is mediated by PI3K signalling downstream of the Ca2+ influx. Conclusions and Implications The TRPV-dependent phagocytosis-enhancing effect of CBD suggests that pharmacological modification of TRPV channel activity could be a rational approach to treating neuroinflammatory disorders involving changes in microglial function and that CBD is a potential starting point for future development of novel therapeutics acting on the TRPV receptor family. PMID:24641282

  11. Microglial Janus kinase/signal transduction and activator of transcription 3 pathway activity directly impacts astrocyte and spinal neuron characteristics.

    PubMed

    Molet, Jenny; Mauborgne, Annie; Diallo, Mickael; Armand, Vincent; Geny, David; Villanueva, Luis; Boucher, Yves; Pohl, Michel

    2016-01-01

    After peripheral nerve injury microglial reactivity change in the spinal cord is associated with an early activation of Janus kinase (JAK)/STAT3 transduction pathway whose blockade attenuates local inflammation and pain hypersensitivity. However, the consequences of microglial JAK/STAT3-mediated signaling on neighboring cells are unknown. Using an in vitro paradigm we assessed the impact of microglial JAK/STAT3 activity on functional characteristics of astrocytes and spinal cord neurons. Purified rat primary microglia was stimulated with JAK/STAT3 classical activator interleukin-6 in the presence or absence of a selective STAT3 inhibitor and rat primary astrocytes or spinal cord neurons were exposed to microglia conditioned media (CM). JAK/STAT3 activity-generated microglial CM modulated both astrocyte and neuron characteristics. Beyond inducing mRNA expression changes in various targets of interest in astrocytes and neurons, microglia CM activated c-Jun N-terminal kinase, STAT3 and NF-κB intracellular pathways in astrocytes and promoted their proliferation. Without modifying neuronal excitability or survival, CM affected the nerve processes morphology and distribution of the post-synaptic density protein 95, a marker of glutamatergic synaptic contacts. These findings show that JAK/STAT3 activity in microglia impacts the functional characteristics of astrocytes and neurons. This suggests its participation in spinal cord tissue plasticity and remodeling occurring after peripheral nerve injury. We show that the activity of JAK/STAT3 pathway in microglial cells confers them a specific signaling modality toward neighboring cells, promoting astrocyte proliferation and changes in neuronal morphology. These in vitro data suggest that the early JAK/STAT3 activation in spinal cord microglia, associated with peripheral nerve injury, participates in functional alteration of various cell populations and in spinal tissue remodeling. PMID:26440453

  12. Subneurotoxic copper(II)-induced NF-κB-dependent microglial activation is associated with mitochondrial ROS.

    PubMed

    Hu, Zhuqin; Yu, Fengxiang; Gong, Ping; Qiu, Yu; Zhou, Wei; Cui, Yongyao; Li, Juan; Chen, Hongzhuan

    2014-04-15

    Microglia-mediated neuroinflammation and the associated neuronal damage play critical roles in the pathogenesis of neurodegenerative disorders. Evidence shows an elevated concentration of extracellular copper(II) in the brains of these disorders, which may contribute to neuronal death through direct neurotoxicity. Here we explored whether extracellular copper(II) triggers microglial activation. Primary rat microglia and murine microglial cell line BV-2 cells were cultured and treated with copper(II). The content of tumor necrosis factor-α (TNF-α) and nitric oxide in the medium was determined. Extracellular hydrogen peroxide was quantified by a fluorometric assay with Amplex Red. Mitochondrial superoxide was measured by MitoSOX oxidation. At subneurotoxic concentrations, copper(II) treatment induced a dose- and time-dependent release of TNF-α and nitric oxide from microglial cells, and caused an indirect, microglia-mediated neurotoxicity that was blocked by inhibition of TNF-α and nitric oxide production. Copper(II)-initiated microglial activation was accompanied with reduced IкB-α expression as well as phosphorylation and translocation of nuclear factor-κB (NF-κB) p65 and was blocked by NF-κB inhibitors (BAY11-7082 and SC-514). Moreover, copper(II) treatment evoked a rapid release of hydrogen peroxide from microglial cells, an effect that was not affected by NADPH oxidase inhibitors. N-acetyl-cysteine, a scavenger of reactive oxygen species (ROS), abrogated copper(II)-elicited microglial release of TNF-α and nitric oxide and subsequent neurotoxicity. Importantly, mitochondrial production of superoxide, paralleled to extracellular release of hydrogen peroxide, was induced after copper(II) stimulation. Our findings suggest that extracellular copper(II) at subneurotoxic concentrations could trigger NF-κB-dependent microglial activation and subsequent neurotoxicity. NADPH oxidase-independent, mitochondria-derived ROS may be involved in this activation. PMID

  13. Neonatal binge alcohol exposure increases microglial activation in the developing rat hippocampus.

    PubMed

    Boschen, K E; Ruggiero, M J; Klintsova, A Y

    2016-06-01

    Aberrant activation of the developing immune system can have long-term negative consequences on cognition and behavior. Teratogens, such as alcohol, activate microglia, the brain's resident immune cells, which could contribute to the lifelong deficits in learning and memory observed in humans with Fetal Alcohol Spectrum Disorders (FASD) and in rodent models of FASD. The current study investigates the microglial response of the brain 24h following neonatal alcohol exposure (postnatal days (PDs) 4-9, 5.25g/kg/day). On PD10, microglial cell counts and area of cell territory were assessed using unbiased stereology in the hippocampal subfields CA1, CA3 and dentate gyrus (DG), and hippocampal expression of pro- and anti-inflammatory genes was analyzed. A significant decrease in microglial cell counts in CA1 and DG was found in alcohol-exposed and sham-intubated (SI) animals compared to undisturbed suckle controls (SCs), suggesting overlapping effects of alcohol exposure and intubation alone on the neuroimmune response. Cell territory was decreased in alcohol-exposed animals in CA1, CA3, and DG compared to controls, suggesting the microglia have shifted to a more activated state following alcohol treatment. Furthermore, both alcohol-exposed and SI animals had increased levels of pro-inflammatory cytokines IL-1β, TNF-α, CD11b, and CCL4; in addition, CCL4 was significantly increased in alcohol-exposed animals compared to SI as well. Alcohol-exposed animals also showed increased levels of anti-inflammatory cytokine TGF-β compared to both SI and SCs. In summary, the number and activation of microglia in the neonatal hippocampus are both affected in a rat model of FASD, along with increased gene expression of pro- and anti-inflammatory cytokines. This study shows that alcohol exposure during development induces a neuroimmune response, potentially contributing to long-term alcohol-related changes to cognition, behavior and immune function. PMID:26996510

  14. The PPARalpha Agonist Fenofibrate Preserves Hippocampal Neurogenesis and Inhibits Microglial Activation After Whole-Brain Irradiation

    SciTech Connect

    Ramanan, Sriram; Kooshki, Mitra; Zhao Weiling; Hsu, F.-C.; Riddle, David R.; Robbins, Mike E.

    2009-11-01

    Purpose: Whole-brain irradiation (WBI) leads to cognitive impairment months to years after radiation. Numerous studies suggest that decreased hippocampal neurogenesis and microglial activation are involved in the pathogenesis of WBI-induced brain injury. The goal of this study was to investigate whether administration of the peroxisomal proliferator-activated receptor (PPAR) alpha agonist fenofibrate would prevent the detrimental effect of WBI on hippocampal neurogenesis. Methods and Materials: For this study, 129S1/SvImJ wild-type and PPARalpha knockout mice that were fed either regular or 0.2% wt/wt fenofibrate-containing chow received either sham irradiation or WBI (10-Gy single dose of {sup 137}Cs gamma-rays). Mice were injected intraperitoneally with bromodeoxyuridine to label the surviving cells at 1 month after WBI, and the newborn neurons were counted at 2 months after WBI by use of bromodeoxyuridine/neuronal nuclei double immunofluorescence. Proliferation in the subgranular zone and microglial activation were measured at 1 week and 2 months after WBI by use of Ki-67 and CD68 immunohistochemistry, respectively. Results: Whole-brain irradiation led to a significant decrease in the number of newborn hippocampal neurons 2 months after it was performed. Fenofibrate prevented this decrease by promoting the survival of newborn cells in the dentate gyrus. In addition, fenofibrate treatment was associated with decreased microglial activation in the dentate gyrus after WBI. The neuroprotective effects of fenofibrate were abolished in the knockout mice, indicating a PPARalpha-dependent mechanism or mechanisms. Conclusions: These data highlight a novel role for PPARalpha ligands in improving neurogenesis after WBI and offer the promise of improving the quality of life for brain cancer patients receiving radiotherapy.

  15. Absence of CD14 Delays Progression of Prion Diseases Accompanied by Increased Microglial Activation

    PubMed Central

    Sakai, Keiko; Hasebe, Rie; Takahashi, Yusuke; Song, Chang-Hyun; Suzuki, Akio; Yamasaki, Takeshi

    2013-01-01

    Prion diseases are fatal neurodegenerative disorders characterized by accumulation of PrPSc, vacuolation of neurons and neuropil, astrocytosis, and microglial activation. Upregulation of gene expressions of innate immunity-related factors, including complement factors and CD14, is observed in the brains of mice infected with prions even in the early stage of infections. When CD14 knockout (CD14−/−) mice were infected intracerebrally with the Chandler and Obihiro prion strains, the mice survived longer than wild-type (WT) mice, suggesting that CD14 influences the progression of the prion disease. Immunofluorescence staining that can distinguish normal prion protein from the disease-specific form of prion protein (PrPSc) revealed that deposition of PrPSc was delayed in CD14−/− mice compared with WT mice by the middle stage of the infection. Immunohistochemical staining with Iba1, a marker for activated microglia, showed an increased microglial activation in prion-infected CD14−/− mice compared to WT mice. Interestingly, accompanied by the increased microglial activation, anti-inflammatory cytokines interleukin-10 (IL-10) and transforming growth factor β (TGF-β) appeared to be expressed earlier in prion-infected CD14−/− mice. In contrast, IL-1β expression appeared to be reduced in the CD14−/− mice in the early stage of infection. Double immunofluorescence staining demonstrated that CD11b- and Iba1-positive microglia mainly produced the anti-inflammatory cytokines, suggesting anti-inflammatory status of microglia in the CD14−/− mice in the early stage of infection. These results imply that CD14 plays a role in the disease progression by suppressing anti-inflammatory responses in the brain in the early stage of infection. PMID:24089559

  16. Ghrelin Inhibits Oligodendrocyte Cell Death by Attenuating Microglial Activation

    PubMed Central

    Lee, Jee Youn

    2014-01-01

    Background Recently, we reported the antiapoptotic effect of ghrelin in spinal cord injury-induced apoptotic cell death of oligodendrocytes. However, how ghrelin inhibits oligodendrocytes apoptosis, is still unknown. Therefore, in the present study, we examined whether ghrelin inhibits microglia activation and thereby inhibits oligodendrocyte apoptosis. Methods Using total cell extracts prepared from BV-2 cells activated by lipopolysaccharide (LPS) with or without ghrelin, the levels of p-p38 phosphor-p38 mitogen-activated protein kinase (p-p38MAPK), phospho-c-Jun N-terminal kinase (pJNK), p-c-Jun, and pro-nerve growth factor (proNGF) were examined by Western blot analysis. Reactive oxygen species (ROS) production was investigated by using dichlorodihydrofluorescein diacetate. To examine the effect of ghrelin on oligodendrocyte cell death, oligodendrocytes were cocultured in transwell chambers of 24-well plates with LPS-stimulated BV-2 cells. After 48 hours incubation, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and terminal deoxynucleotidyl transferase 2'-deoxyuridine, 5'-triphosphate nick end labeling staining were assessed. Results Ghrelin treatment significantly decreased levels of p-p38MAPK, p-JNK, p-c-Jun, and proNGF in LPS-stimulated BV-2 cells. ROS production increased in LPS-stimulated BV-2 cells was also significantly inhibited by ghrelin treatment. In addition, ghrelin significantly inhibited oligodendrocyte cell death when cocultured with LPS-stimulated BV-2 cells. Conclusion Ghrelin inhibits oligodendrocyte cell death by decreasing proNGF and ROS production as well as p38MAPK and JNK activation in activated microglia as an anti-inflammatory hormone. PMID:25309797

  17. Excessive α-tocopherol exacerbates microglial activation and brain injury caused by acute ischemic stroke

    PubMed Central

    Khanna, Savita; Heigel, Mallory; Weist, Jessica; Gnyawali, Surya; Teplitsky, Seth; Roy, Sashwati; Sen, Chandan K.; Rink, Cameron

    2015-01-01

    The vitamin E family includes both tocopherols and tocotrienols, where α-tocopherol (αTOC) is the most bioavailable form. Clinical trials testing the therapeutic efficacy of high-dose αTOC against stroke have largely failed or reported negative outcomes when a “more is better” approach to supplementation (>400 IU/d) was used. This work addresses mechanisms by which supraphysiologic αTOC may contribute to stroke-induced brain injury. Ischemic stroke injury and the neuroinflammatory response were studied in tocopherol transfer protein-deficient mice maintained on a diet containing αTOC vitamin E at the equivalent human dose of 1680 IU/d. Ischemic stroke-induced brain injury was exacerbated in the presence of supraphysiologic brain αTOC levels. At 48 h after stroke, S100B and RAGE expression was increased in stroke-affected cortex of mice with elevated brain αTOC levels. Such increases were concomitant with aggravated microglial activation and neuroinflammatory signaling. A poststroke increase in markers of oxidative injury and neurodegeneration in the presence of elevated brain αTOC establish that at supraphysiologic levels, αTOC potentiates neuroinflammatory responses to acute ischemic stroke. Exacerbation of microglial activation by excessive αTOC likely depends on its unique cell signaling regulatory properties independent of antioxidant function. Against the background of clinical failure for high-dose αTOC, outcomes of this work identify risk for exacerbating stroke-induced brain injury as a result of supplementing diet with excessive levels of αTOC.—Khanna, S., Heigel,M., Weist, J., Gnyawali, S., Teplitsky, S., Roy, S., Sen, C. K., Rink, C. Excessive α-tocopherol exacerbates microglial activation and brain injury caused by acute ischemic stroke. PMID:25411436

  18. Maternal immune activation evoked by polyinosinic:polycytidylic acid does not evoke microglial cell activation in the embryo

    PubMed Central

    Smolders, Silke; Smolders, Sophie M. T.; Swinnen, Nina; Gärtner, Annette; Rigo, Jean-Michel; Legendre, Pascal; Brône, Bert

    2015-01-01

    Several studies have indicated that inflammation during pregnancy increases the risk for the development of neuropsychiatric disorders in the offspring. Morphological brain abnormalities combined with deviations in the inflammatory status of the brain can be observed in patients of both autism and schizophrenia. It was shown that acute infection can induce changes in maternal cytokine levels which in turn are suggested to affect fetal brain development and increase the risk on the development of neuropsychiatric disorders in the offspring. Animal models of maternal immune activation reproduce the etiology of neurodevelopmental disorders such as schizophrenia and autism. In this study the poly (I:C) model was used to mimic viral immune activation in pregnant mice in order to assess the activation status of fetal microglia in these developmental disorders. Because microglia are the resident immune cells of the brain they were expected to be activated due to the inflammatory stimulus. Microglial cell density and activation level in the fetal cortex and hippocampus were determined. Despite the presence of a systemic inflammation in the pregnant mice, there was no significant difference in fetal microglial cell density or immunohistochemically determined activation level between the control and inflammation group. These data indicate that activation of the fetal microglial cells is not likely to be responsible for the inflammation induced deficits in the offspring in this model. PMID:26300736

  19. Imaging Microglial Activation with TSPO PET: Lighting Up Neurologic Diseases?

    PubMed

    Vivash, Lucy; O'Brien, Terence J

    2016-02-01

    Neuroinflammation is implicated in the pathogenesis of a wide range of neurologic and neuropsychiatric diseases. For over 20 years, (11)C-PK11195 PET, which aims to image expression of the translocator protein (TSPO) on activated microglia in the brain, has been used in preclinical and clinical research to investigate neuroinflammation in vivo in patients with brain diseases. However, (11)C-PK11195 suffers from two major limitations: its low brain permeability and high nonspecific and plasma binding results in a low signal-to-noise ratio, and the use of (11)C restricts its use to PET research centers and hospitals with an on-site cyclotron. In recent years, there has been a great deal of work into the development of new TSPO-specific PET radiotracers. This work has focused on fluorinated radiotracers, which would enable wider use and improved signal-to-noise ratios. These radiotracers have been utilized in preclinical and clinical studies of several neurologic diseases with varying degrees of success. Unfortunately, the application of these second-generation TSPO radiotracers has revealed additional problems, including a polymorphism that affects TSPO binding. In this review, the developments in TSPO imaging are discussed, and current limitations and suggestions for future directions are explored. PMID:26697963

  20. Delayed activation of human microglial cells by high dose ionizing radiation.

    PubMed

    Chen, Hongxin; Chong, Zhao Zhong; De Toledo, Sonia M; Azzam, Edouard I; Elkabes, Stella; Souayah, Nizar

    2016-09-01

    Recent studies have shown that microglia affects the fate of neural stem cells in response to ionizing radiation, which suggests a role for microglia in radiation-induced degenerative outcomes. We therefore investigated the effects of γ-irradiation on cell survival, proliferation, and activation of microglia and explored associated mechanisms. Specifically, we evaluated cellular and molecular changes associated with exposure of human microglial cells (CHME5) to low and high doses of acute cesium-137 γ rays. Twenty-four hours after irradiation, cell cycle analyses revealed dose-dependent decreases in the fraction of cells in S and G2/M phase, which correlated with significant oxidative stress. By one week after irradiation, 20-30% of the cells exposed to high doses of γ rays underwent apoptosis, which correlated with significant concomitant decrease in metabolic activity as assessed by the MTT assay, and microglial activation as judged by both morphological changes and increased expression of Glut-5 and CR43. These changes were associated with increases in the mRNA levels for IL-1α, IL-10 and TNFα. Together, the results show that human CHME5 microglia are relatively resistant to low and moderate doses of γ rays, but are sensitive to acute high doses, and that CHME5 cells are a useful tool for in vitro study of human microglia. PMID:27265419

  1. Rapamycin protects neurons from brain contusion-induced inflammatory reaction via modulation of microglial activation

    PubMed Central

    SONG, QI; XIE, DUJIANG; PAN, SHIYONG; XU, WEIJUN

    2015-01-01

    The inflammatory reaction is important in secondary injury following traumatic brain injury (TBI). Rapamycin has been demonstrated as a neuroprotective agent in a mouse model of TBI, however, there is a lack of data regarding the effects of rapamycin on the inflammatory reaction following TBI. Therefore, the present study was designed to assess the effects of treatment with rapamycin on inflammatory reactions and examine the possible involvement of microglial activation following TBI. Male imprinting control region mice were randomly divided into four groups: Sham group (n=23), TBI group (n=23), TBI + dimethyl sulfoxide (DMSO) group (n=31) and TBI + rapamycin group (n=31). Rapamycin was dissolved in DMSO (50 mg/ml) and injected 30 min after TBI (2 mg/Kg; intraperitoneally). A weight-drop model of TBI was induced, and the brain tissues were harvested 24 h after TBI. The findings indicated that the administration of rapamycin following TBI was associated with decreased levels of activated microglia and neuron degeneration at the peri-injury site, reduced levels of proinflammatory cytokines and increased neurobehavioral function, possibly mediated by inactivation of the mammalian target of rapamycin pathway. The results of the present study offer novel insight into the mechanisms responsible for the anti-neuroinflammatory effects of rapamycin, possibly involving the modulation of microglial activation. PMID:26458361

  2. NADPH oxidase 2-derived reactive oxygen species in the hippocampus might contribute to microglial activation in postoperative cognitive dysfunction in aged mice.

    PubMed

    Qiu, Li-Li; Ji, Mu-Huo; Zhang, Hui; Yang, Jiao-Jiao; Sun, Xiao-Ru; Tang, Hui; Wang, Jing; Liu, Wen-Xue; Yang, Jian-Jun

    2016-01-01

    Microglial activation plays a key role in the development of postoperative cognitive dysfunction (POCD). Nox2, one of the main isoforms of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in the central nervous system, is a predominant source of reactive oxygen species (ROS) overproduction in phagocytes including microglia. We therefore hypothesized that Nox2-induced microglial activation is involved in the development of POCD. Sixteen-month-old C57BL/6 mice were subjected to exploratory laparotomy with isoflurane anesthesia to mimic the clinical human abdominal surgery. Behavioral tests were performed at 6 and 7 d post-surgery with open field and fear conditioning tests, respectively. The levels of Nox2, 8-hydroxy-2'-deoxyguanosine (8-OH-dG, a marker of DNA oxidation), CD11b (a marker of microglial activation), interleukin-1β (IL-1β), and brain-derived neurotrophic factor (BDNF) were determined in the hippocampus and prefrontal cortex at 1 d and 7 d post-surgery, respectively. For the interventional study, mice were treated with a NADPH oxidase inhibitor apocynin (APO). Our results showed that exploratory laparotomy with isoflurane anesthesia impaired the contextual fear memory, increased expression of Nox2, 8-OH-dG, CD11b, and IL-1β, and down-regulated BDNF expression in the hippocampus at 7 d post-surgery. The surgery-induced microglial activation and neuroinflammation persisted to 7 d after surgery in the hippocampus, but only at 1 d in the prefrontal cortex. Notably, administration with APO could rescue these surgery-induced cognitive impairments and associated brain pathology. Together, our data suggested that Nox2-derived ROS in hippocampal microglia, at least in part, contributes to subsequent neuroinflammation and cognitive impairments induced by surgery in aged mice. PMID:26254234

  3. NG2 expression in microglial cells affects the expression of neurotrophic and proinflammatory factors by regulating FAK phosphorylation

    PubMed Central

    Zhu, Lie; Su, Qing; Jie, Xiang; Liu, Antang; Wang, Hui; He, Beiping; Jiang, Hua

    2016-01-01

    Neural/glial antigen 2 (NG2), a chondroitin sulfate proteoglycan, is significantly upregulated in a subset of glial cells in the facial motor nucleus (FMN) following CNS injury. NG2 is reported to promote the resulting inflammatory reaction, however, the mechanism by which NG2 mediates these effects is yet to be determined. In this study, we examined the changes in NG2 expressing microglial cells in the FMN in response to facial nerve axotomy (FNA) in mice. Our findings indicated that NG2 expression was progressively induced and upregulated specifically in the ipsilateral facial nucleus following FNA. To further investigate the effects of NG2 expression, in vivo studies in NG2-knockout mice and in vitro studies in rat microglial cells transfected with NG2 shRNAs were performed. Abolition of NG2 expression both in vitro and in vivo resulted in increased expression of neurotrophic factors (nerve growth factor and glial derived neurotrophic factor), decreased expression of inflammatory mediators (tumor necrosis factor-α and interleukin-1β) and decreased apoptosis in the ipsilateral facial nucleus in response to FNA. Furthermore, we demonstrated the role of FAK in these NG2-induced effects. Taken together, our findings suggest that NG2 expression mediates inflammatory reactions and neurodegeneration in microglial cells in response to CNS injury, potentially by regulating FAK phosphorylation. PMID:27306838

  4. Down-regulation of BNIP3 by olomoucine, a CDK inhibitor, reduces LPS- and NO-induced cell death in BV2 microglial cells.

    PubMed

    Tsou, Yu-Chi; Wang, Hsiao-Hsien; Hsieh, Chii-Cheng; Sun, Kuang-Hui; Sun, Guang-Huan; Jhou, Ren-Shiang; Lin, Tz-I; Lu, Shou-Yun; Liu, Huan-Yun; Tang, Shye-Jye

    2016-08-15

    Proinflammatory responses eliciting the microglial production of cytokines and nitric oxide (NO) have been reported to play a crucial role in the acute and chronic pathogenic effects of neurodegeneration. Chemical inhibitors of cyclin-dependent kinases (CDKs) may prevent the progression of neurodegeneration by both limiting cell proliferation and reducing cell death. However, the mechanism underlying the protective effect of CDK inhibitors on microglia remains unexplored. In this study, we found that olomoucine, a CDK inhibitor, alleviated lipopolysaccharide (LPS)-induced BV2 microglial cell death by reducing the generation of NO and inhibiting the gene expression of proinflammatory cytokines. In addition, olomoucine reduced inducible NO synthase promoter activity and alleviated NF-κB- and E2F-mediated transcriptional activation. NO-induced cell death involved mitochondrial disruptions such as cytochrome c release and loss of mitochondrial membrane potential, and pretreatment with olomoucine prior to NO exposure reduced these disruptions. Microarray analysis revealed that olomoucine treatment induced prominent down-regulation of Bcl2/adenovirus E1B 19-kDa-interacting protein 3 (BNIP3), a pro-apoptotic Bcl-2 family protein that is involved in mitochondrial disruption. As BNIP3 knock-down significantly increased the viability of LPS- and NO-treated BV2 cells, we conclude that olomoucine may protect cells by limiting proinflammatory responses, thereby reducing NO generation. Simultaneously, down-regulation of BNIP3 prevents NO stimulation from inducing mitochondrial disruption. PMID:27345388

  5. Subneurotoxic copper(II)-induced NF-κB-dependent microglial activation is associated with mitochondrial ROS

    SciTech Connect

    Hu, Zhuqin; Yu, Fengxiang; Gong, Ping; Qiu, Yu; Zhou, Wei; Cui, Yongyao; Li, Juan Chen, Hongzhuan

    2014-04-15

    Microglia-mediated neuroinflammation and the associated neuronal damage play critical roles in the pathogenesis of neurodegenerative disorders. Evidence shows an elevated concentration of extracellular copper(II) in the brains of these disorders, which may contribute to neuronal death through direct neurotoxicity. Here we explored whether extracellular copper(II) triggers microglial activation. Primary rat microglia and murine microglial cell line BV-2 cells were cultured and treated with copper(II). The content of tumor necrosis factor-α (TNF-α) and nitric oxide in the medium was determined. Extracellular hydrogen peroxide was quantified by a fluorometric assay with Amplex Red. Mitochondrial superoxide was measured by MitoSOX oxidation. At subneurotoxic concentrations, copper(II) treatment induced a dose- and time-dependent release of TNF-α and nitric oxide from microglial cells, and caused an indirect, microglia-mediated neurotoxicity that was blocked by inhibition of TNF-α and nitric oxide production. Copper(II)-initiated microglial activation was accompanied with reduced IkB-α expression as well as phosphorylation and translocation of nuclear factor-κB (NF-κB) p65 and was blocked by NF-κB inhibitors (BAY11-7082 and SC-514). Moreover, copper(II) treatment evoked a rapid release of hydrogen peroxide from microglial cells, an effect that was not affected by NADPH oxidase inhibitors. N-acetyl-cysteine, a scavenger of reactive oxygen species (ROS), abrogated copper(II)-elicited microglial release of TNF-α and nitric oxide and subsequent neurotoxicity. Importantly, mitochondrial production of superoxide, paralleled to extracellular release of hydrogen peroxide, was induced after copper(II) stimulation. Our findings suggest that extracellular copper(II) at subneurotoxic concentrations could trigger NF-κB-dependent microglial activation and subsequent neurotoxicity. NADPH oxidase-independent, mitochondria-derived ROS may be involved in this activation

  6. Substance P Exacerbates Dopaminergic Neurodegeneration through Neurokinin-1 Receptor-Independent Activation of Microglial NADPH Oxidase

    PubMed Central

    Chu, Chun-Hsien; Qian, Li; Chen, Shih-Heng; Wilson, Belinda; Oyarzabal, Esteban; Jiang, Lulu; Ali, Syed; Robinson, Bonnie; Kim, Hyoung-Chun

    2014-01-01

    Although dysregulated substance P (SP) has been implicated in the pathophysiology of Parkinson's disease (PD), how SP affects the survival of dopaminergic neurons remains unclear. Here, we found that mice lacking endogenous SP (TAC1−/−), but not those deficient in the SP receptor (neurokinin-1 receptor, NK1R), were more resistant to lipopolysaccharide (LPS)- and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced nigral dopaminergic neurodegeneration than wild-type controls, suggesting a NK1R-independent toxic action of SP. In vitro dose–response studies revealed that exogenous SP enhanced LPS- and 1-methyl-4-phenylpyridinium (MPP+)-induced dopaminergic neurodegeneration in a bimodal manner, peaking at submicromolar and subpicomolar concentrations, but was substantially less effective at intermediate concentrations. Mechanistically, the actions of submicromolar levels of SP were NK1R-dependent, whereas subpicomolar SP-elicited actions required microglial NADPH oxidase (NOX2), the key superoxide-producing enzyme, but not NK1R. Subpicomolar concentrations of SP activated NOX2 by binding to the catalytic subunit gp91phox and inducing membrane translocation of the cytosolic subunits p47phox and p67phox. The importance of NOX2 was further corroborated by showing that inhibition or disruption of NOX2 blocked subpicomolar SP-exacerbated neurotoxicity. Together, our findings revealed a critical role of microglial NOX2 in mediating the neuroinflammatory and dopaminergic neurodegenerative effects of SP, which may provide new insights into the pathogenesis of PD. PMID:25209287

  7. Vaccinium bracteatum Thunb. Exerts Anti-Inflammatory Activity by Inhibiting NF-κB Activation in BV-2 Microglial Cells

    PubMed Central

    Kwon, Seung-Hwan; Ma, Shi-Xun; Ko, Yong-Hyun; Seo, Jee-Yeon; Lee, Bo-Ram; Lee, Taek Hwan; Kim, Sun Yeou; Lee, Seok-Yong; Jang, Choon-Gon

    2016-01-01

    This study was designed to evaluate the pharmacological effects of Vaccinium bracteatum Thunb. methanol extract (VBME) on microglial activation and to identify the underlying mechanisms of action of these effects. The anti-inflammatory properties of VBME were studied using lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. We measured the production of nitric oxide (NO), inducible NO synthase (iNOS), cyclooxygenase (COX)-2, prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6) as inflammatory parameters. We also examined the effect of VBME on intracellular reactive oxygen species (ROS) production and the activity of nuclear factor-kappa B p65 (NF-κB p65). VBME significantly inhibited LPS-induced production of NO and PGE2 and LPS-mediated upregulation of iNOS and COX-2 expression in a dose-dependent manner; importantly, VBME was not cytotoxic. VBME also significantly reduced the generation of the pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. In addition, VBME significantly dampened intracellular ROS production and suppressed NF-κB p65 translocation by blocking IκB-α phosphorylation and degradation in LPS-stimulated BV2 cells. Our findings indicate that VBME inhibits the production of inflammatory mediators in BV-2 microglial cells by suppressing NF-κB signaling. Thus, VBME may be useful in the treatment of neurodegenerative diseases due to its ability to inhibit inflammatory mediator production in activated BV-2 microglial cells. PMID:27169820

  8. HSP60 mediates the neuroprotective effects of curcumin by suppressing microglial activation

    PubMed Central

    Ding, Feijia; Li, Fan; Li, Yunhong; Hou, Xiaolin; Ma, Yi; Zhang, Nan; Ma, Jiao; Zhang, Rui; Lang, Bing; Wang, Hongyan; Wang, Yin

    2016-01-01

    Curcumin has anti-inflammatory and antioxidant properties and has been widely used to treat or prevent neurodegenerative diseases. However, the mechanisms underlying the neuroprotective effects of curcumin are not well known. In the present study, the effect of curcumin on lipopolysaccharide (LPS)-stimulated BV2 mouse microglia cells was investigated using enzyme-linked immunosorbent assays of the culture medium and western blotting of cell lysates. The results showed that curcumin significantly inhibited the LPS-induced expression and release of heat shock protein 60 (HSP60) in the BV2 cells. The level of heat shock factor (HSF)-1 was upregulated in LPS-activated BV2 microglia, indicating that the increased expression of HSP60 was driven by HSF-1 activation. However, the increased HSF-1 level was downregulated by curcumin. Extracellular HSP60 is a ligand of Toll-like receptor 4 (TLR-4), and the level of the latter was increased in the LPS-activated BV2 microglia and inhibited by curcumin. The activation of TLR-4 is known to be associated with the activation of myeloid differentiation primary response 88 (MyD88) and nuclear factor (NF)-κB, with the subsequent production of proinflammatory and neurotoxic factors. In the present study, curcumin demonstrated marked suppression of the LPS-induced expression of MyD88, NF-κB, caspase-3, inducible nitric oxide synthase, tumor necrosis factor-α, interleukin (IL)-1β and IL-6 in the microglia. These results indicate that curcumin may exert its neuroprotective and anti-inflammatory effects by inhibiting microglial activation through the HSP60/TLR-4/MyD88/NF-κB signaling wpathway. Therefore, curcumin may be useful for the treatment of neurodegenerative diseases that are associated with microglial activation. PMID:27446282

  9. Inhibition of microglial activity alters spinal wide dynamic range neuron discharge and reduces microglial Toll-like receptor 4 expression in neuropathic rats.

    PubMed

    Nazemi, Samad; Manaheji, Homa; Noorbakhsh, Syyed Mohammad; Zaringhalam, Jalal; Sadeghi, Mehdi; Mohammad-Zadeh, Mohammad; Haghparast, Abbas

    2015-07-01

    It is believed that neuropathic pain results from aberrant neuronal discharges although some evidence suggests that the activation of glia cells contributes to pain after an injury to the nervous system. This study aimed to evaluate the role of microglial activation on the hyper-responsiveness of wide dynamic range neurons (WDR) and Toll-like receptor 4 (TLR4) expressions in a chronic constriction injury (CCI) model of neuropathic pain in rats. Adult male Wistar rats (230 ± 30 g) underwent surgery for induction of CCI neuropathy. Six days after surgery, administration of minocycline (10, 20, and 40 mg/kg, i.p.) was initiated and continued until day 14. After administration of the last dose of minocycline or saline, a behavioral test was conducted, then animals were sacrificed and lumbar segments of the spinal cord were collected for Western blot analysis of TLR4 expression. The electrophysiological properties of WDR neurons were investigated by single unit recordings in separate groups. The findings showed that after CCI, in parallel with thermal hyperalgesia, the expression of TLR4 in the spinal cord and the evoked response of the WDR neurons to electrical, mechanical, and thermal stimulation significantly increased. Post-injury administration of minocycline effectively decreased thermal hyperalgesia, TLR4 expression, and hyper-responsiveness of WDR neurons in CCI rats. The results of this study indicate that post-injury, repeated administration of minocycline attenuated neuropathic pain by suppressing microglia activation and reducing WDR neuron hyper-responsiveness. This study confirms that post-injury modulation of microglial activity is a new strategy for treating neuropathic pain. PMID:25933029

  10. Microglial activation induced by factor(s) contained in sera from Alzheimer-related ApoE genotypes.

    PubMed

    Lombardi, V R; García, M; Cacabelos, R

    1998-11-15

    /4 genotype contain factor(s) which are able to induce morphological changes, as measured by an increase in the ameboid cell type. In addition, major histocompatibility complex (MHC) class II antigen expression, as measured by flow cytometric analysis, and interleukin-1beta (IL-1beta) release as measured by enzyme linked immunoadsorbent assay (ELISA), in comparison with control groups and lipopolysaccharide (LPS)-treated cells, clearly demonstrate a direct effect of ApoE 3/4 and 4/4 and/or an indirect effect mediated by the release of IL-1beta on microglia activation. These results strongly suggest that primary in vitro microglial cell cultures can be used as a screening model to test human sera as well as the effect of new potential drugs aimed at down-regulating microglia activation. PMID:9822164

  11. Cocaine promotes oxidative stress and microglial-macrophage activation in rat cerebellum.

    PubMed

    López-Pedrajas, Rosa; Ramírez-Lamelas, Dolores T; Muriach, Borja; Sánchez-Villarejo, María V; Almansa, Inmaculada; Vidal-Gil, Lorena; Romero, Francisco J; Barcia, Jorge M; Muriach, María

    2015-01-01

    Different mechanisms have been suggested for cocaine neurotoxicity, including oxidative stress alterations. Nuclear factor kappa B (NF-κB), considered a sensor of oxidative stress and inflammation, is involved in drug toxicity and addiction. NF-κB is a key mediator for immune responses that induces microglial/macrophage activation under inflammatory processes and neuronal injury/degeneration. Although cerebellum is commonly associated to motor control, muscular tone, and balance. Its relation with addiction is getting relevance, being associated to compulsive and perseverative behaviors. Some reports indicate that cerebellar microglial activation induced by cannabis or ethanol, promote cerebellar alterations and these alterations could be associated to addictive-related behaviors. After considering the effects of some drugs on cerebellum, the aim of the present work analyzes pro-inflammatory changes after cocaine exposure. Rats received daily 15 mg/kg cocaine i.p., for 18 days. Reduced and oxidized forms of glutathione (GSH) and oxidized glutathione (GSSG), glutathione peroxidase (GPx) activity and glutamate were determined in cerebellar homogenates. NF-κB activity, CD68, and GFAP expression were determined. Cerebellar GPx activity and GSH/GSSG ratio are significantly decreased after cocaine exposure. A significant increase of glutamate concentration is also observed. Interestingly, increased NF-κB activity is also accompanied by an increased expression of the lysosomal mononuclear phagocytic marker ED1 without GFAP alterations. Current trends in addiction biology are focusing on the role of cerebellum on addictive behaviors. Cocaine-induced cerebellar changes described herein fit with previosus data showing cerebellar alterations on addict subjects and support the proposed role of cerebelum in addiction. PMID:26283916

  12. Cocaine promotes oxidative stress and microglial-macrophage activation in rat cerebellum

    PubMed Central

    López-Pedrajas, Rosa; Ramírez-Lamelas, Dolores T.; Muriach, Borja; Sánchez-Villarejo, María V.; Almansa, Inmaculada; Vidal-Gil, Lorena; Romero, Francisco J.; Barcia, Jorge M.; Muriach, María

    2015-01-01

    Different mechanisms have been suggested for cocaine neurotoxicity, including oxidative stress alterations. Nuclear factor kappa B (NF-κB), considered a sensor of oxidative stress and inflammation, is involved in drug toxicity and addiction. NF-κB is a key mediator for immune responses that induces microglial/macrophage activation under inflammatory processes and neuronal injury/degeneration. Although cerebellum is commonly associated to motor control, muscular tone, and balance. Its relation with addiction is getting relevance, being associated to compulsive and perseverative behaviors. Some reports indicate that cerebellar microglial activation induced by cannabis or ethanol, promote cerebellar alterations and these alterations could be associated to addictive-related behaviors. After considering the effects of some drugs on cerebellum, the aim of the present work analyzes pro-inflammatory changes after cocaine exposure. Rats received daily 15 mg/kg cocaine i.p., for 18 days. Reduced and oxidized forms of glutathione (GSH) and oxidized glutathione (GSSG), glutathione peroxidase (GPx) activity and glutamate were determined in cerebellar homogenates. NF-κB activity, CD68, and GFAP expression were determined. Cerebellar GPx activity and GSH/GSSG ratio are significantly decreased after cocaine exposure. A significant increase of glutamate concentration is also observed. Interestingly, increased NF-κB activity is also accompanied by an increased expression of the lysosomal mononuclear phagocytic marker ED1 without GFAP alterations. Current trends in addiction biology are focusing on the role of cerebellum on addictive behaviors. Cocaine-induced cerebellar changes described herein fit with previosus data showing cerebellar alterations on addict subjects and support the proposed role of cerebelum in addiction. PMID:26283916

  13. Ibudilast, a Pharmacologic Phosphodiesterase Inhibitor, Prevents Human Immunodeficiency Virus-1 Tat-Mediated Activation of Microglial Cells

    PubMed Central

    Kiebala, Michelle; Maggirwar, Sanjay B.

    2011-01-01

    Human Immunodeficiency Virus-1 (HIV-1)-associated neurocognitive disorders (HAND) occur, in part, due to the inflammatory response to viral proteins, such as the HIV-1 transactivator of transcription (Tat), in the central nervous system (CNS). Given the need for novel adjunctive therapies for HAND, we hypothesized that ibudilast would inhibit Tat-induced excess production of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNFα) in microglial cells. Ibudilast is a non-selective cyclic AMP phosphodiesterase inhibitor that has recently shown promise as a treatment for neuropathic pain via its ability to attenuate glial cell activation. Accordingly, here we demonstrate that pre-treatment of both human and mouse microglial cells with increasing doses of ibudilast inhibited Tat-induced synthesis of TNFα by microglial cells in a manner dependent on serine/threonine protein phosphatase activity. Ibudilast had no effect on Tat-induced p38 MAP kinase activation, and blockade of adenosine A2A receptor activation did not reverse ibudilast's inhibition of Tat-induced TNFα production. Interestingly, ibudilast reduced Tat-mediated transcription of TNFα, via modulation of nuclear factor-kappa B (NF-κB) signaling, as shown by transcriptional activity of NF-κB and analysis of inhibitor of kappa B alpha (IκBα) stability. Together, our findings shed light on the mechanism of ibudilast's inhibition of Tat-induced TNFα production in microglial cells and may implicate ibudilast as a potential novel adjunctive therapy for the management of HAND. PMID:21494611

  14. Knockout of fractalkine receptor Cx3cr1 does not alter disease or microglial activation in prion-infected mice.

    PubMed

    Striebel, James F; Race, Brent; Carroll, James A; Phillips, Katie; Chesebro, Bruce

    2016-06-01

    Microglial activation is a hallmark of the neuroimmunological response to Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and prion disease. The CX3C chemokine axis consists of fractalkine (CX3CL1) and its receptor (CX3CR1); these are expressed by neurons and microglia respectively, and are known to modulate microglial activation. In prion-infected mice, both Cx3cr1 and Cx3cl1 are altered, suggesting a role in disease. To investigate the influence of CX3C axis signalling on prion disease, we infected Cx3cr1 knockout (Cx3cr1-KO) and control mice with scrapie strains 22L and RML. Deletion of Cx3cr1 had no effect on development of clinical signs or disease incubation period. In addition, comparison of brain tissue from Cx3cr1-KO and control mice revealed no significant differences in cytokine levels, spongiosis, deposition of disease-associated prion protein or microglial activation. Thus, microglial activation during prion infection did not require CX3C axis signalling. PMID:26935332

  15. Administration of DHA Reduces Endoplasmic Reticulum Stress-Associated Inflammation and Alters Microglial or Macrophage Activation in Traumatic Brain Injury

    PubMed Central

    Harvey, Lloyd D.; Yin, Yan; Attarwala, Insiya Y.; Begum, Gulnaz; Deng, Julia; Yan, Hong Q.; Dixon, C. Edward

    2015-01-01

    We investigated the effects of the administration of docosahexaenoic acid (DHA) post-traumatic brain injury (TBI) on reducing neuroinflammation. TBI was induced by cortical contusion injury in Sprague Dawley rats. Either DHA (16 mg/kg in dimethyl sulfoxide) or vehicle dimethyl sulfoxide (1 ml/kg) was administered intraperitonially at 5 min after TBI, followed by a daily dose for 3 to 21 days. TBI triggered activation of microglia or macrophages, detected by an increase of Iba1 positively stained microglia or macrophages in peri-lesion cortical tissues at 3, 7, and 21 days post-TBI. The inflammatory response was further characterized by expression of the proinflammatory marker CD16/32 and the anti-inflammatory marker CD206 in Iba1+ microglia or macrophages. DHA-treated brains showed significantly fewer CD16/32+ microglia or macrophages, but an increased CD206+ phagocytic microglial or macrophage population. Additionally, DHA treatment revealed a shift in microglial or macrophage morphology from the activated, amoeboid-like state into the more permissive, surveillant state. Furthermore, activated Iba1+ microglial or macrophages were associated with neurons expressing the endoplasmic reticulum (ER) stress marker CHOP at 3 days post-TBI, and the administration of DHA post-TBI concurrently reduced ER stress and the associated activation of Iba1+ microglial or macrophages. There was a decrease in nuclear translocation of activated nuclear factor kappa-light-chain-enhancer of activated B cells protein at 3 days in DHA-treated tissue and reduced neuronal degeneration in DHA-treated brains at 3, 7, and 21 days after TBI. In summary, our study demonstrated that TBI mediated inflammatory responses are associated with increased neuronal ER stress and subsequent activation of microglia or macrophages. DHA administration reduced neuronal ER stress and subsequent association with microglial or macrophage polarization after TBI, demonstrating its therapeutic potential to

  16. Administration of DHA Reduces Endoplasmic Reticulum Stress-Associated Inflammation and Alters Microglial or Macrophage Activation in Traumatic Brain Injury.

    PubMed

    Harvey, Lloyd D; Yin, Yan; Attarwala, Insiya Y; Begum, Gulnaz; Deng, Julia; Yan, Hong Q; Dixon, C Edward; Sun, Dandan

    2015-01-01

    We investigated the effects of the administration of docosahexaenoic acid (DHA) post-traumatic brain injury (TBI) on reducing neuroinflammation. TBI was induced by cortical contusion injury in Sprague Dawley rats. Either DHA (16 mg/kg in dimethyl sulfoxide) or vehicle dimethyl sulfoxide (1 ml/kg) was administered intraperitonially at 5 min after TBI, followed by a daily dose for 3 to 21 days. TBI triggered activation of microglia or macrophages, detected by an increase of Iba1 positively stained microglia or macrophages in peri-lesion cortical tissues at 3, 7, and 21 days post-TBI. The inflammatory response was further characterized by expression of the proinflammatory marker CD16/32 and the anti-inflammatory marker CD206 in Iba1(+) microglia or macrophages. DHA-treated brains showed significantly fewer CD16/32(+) microglia or macrophages, but an increased CD206(+) phagocytic microglial or macrophage population. Additionally, DHA treatment revealed a shift in microglial or macrophage morphology from the activated, amoeboid-like state into the more permissive, surveillant state. Furthermore, activated Iba1(+) microglial or macrophages were associated with neurons expressing the endoplasmic reticulum (ER) stress marker CHOP at 3 days post-TBI, and the administration of DHA post-TBI concurrently reduced ER stress and the associated activation of Iba1(+) microglial or macrophages. There was a decrease in nuclear translocation of activated nuclear factor kappa-light-chain-enhancer of activated B cells protein at 3 days in DHA-treated tissue and reduced neuronal degeneration in DHA-treated brains at 3, 7, and 21 days after TBI. In summary, our study demonstrated that TBI mediated inflammatory responses are associated with increased neuronal ER stress and subsequent activation of microglia or macrophages. DHA administration reduced neuronal ER stress and subsequent association with microglial or macrophage polarization after TBI, demonstrating its therapeutic

  17. Increased central microglial activation associated with peripheral cytokine levels in premanifest Huntington's disease gene carriers.

    PubMed

    Politis, Marios; Lahiri, Nayana; Niccolini, Flavia; Su, Paul; Wu, Kit; Giannetti, Paolo; Scahill, Rachael I; Turkheimer, Federico E; Tabrizi, Sarah J; Piccini, Paola

    2015-11-01

    Previous studies have shown activation of the immune system and altered immune response in Huntington's disease (HD) gene carriers. Here, we hypothesized that peripheral and central immune responses could be concurrent pathophysiological events and represent a global innate immune response to the toxic effects of mutant huntingtin in HD gene carriers. We sought to investigate our hypothesis using [(11)C]PK11195 PET as a translocator protein (TSPO) marker of central microglial activation, together with assessment of peripheral plasma cytokine levels in a cohort of premanifest HD gene carriers who were more than a decade from predicted symptomatic conversion. Data were also compared to those from a group of healthy controls matched for age and gender. We found significantly increased peripheral plasma IL-1β levels in premanifest HD gene carriers compared to the group of normal controls (P=0.018). Premanifest HD gene carriers had increased TSPO levels in cortical, basal ganglia and thalamic brain regions (P<0.001). Increased microglial activation in somatosensory cortex correlated with higher plasma levels of IL-1β (rs=0.87, P=0.013), IL-6 (rs=0.85, P=0.013), IL-8 (rs=0.68, P=0.045) and TNF-α (rs=0.79; P=0.013). Our findings provide first in vivo evidence for an association between peripheral and central immune responses in premanifest HD gene carriers, and provide further supporting evidence for the role of immune dysfunction in the pathogenesis of HD. PMID:26297319

  18. Inhibition of microglial activation by elderberry extracts and its phenolic components

    PubMed Central

    Simonyi, Agnes; Chen, Zihong; Jiang, Jinghua; Zong, Yijia; Chuang, Dennis Y.; Gu, Zezong; Lu, Chi-Hua; Fritsche, Kevin L.; Greenlief, C. Michael; Rottinghaus, George E.; Thomas, Andrew L.; Lubahn, Dennis B.; Sun, Grace Y.

    2015-01-01

    Aims Elderberry (Sambucus spp.) is one of the oldest medicinal plants noted for its cardiovascular, anti-inflammatory, and immune-stimulatory properties. In this study, we investigated the anti-inflammatory and anti-oxidant effects of the American elderberry (Sambucus nigra subsp. canadensis) pomace as well as some of the anthocyanins (cyanidin chloride and cyanidin 3-O-glucoside) and flavonols (quercetin and rutin) in bv-2 mouse microglial cells. Main methods The bv-2 cells were pretreated with elderberry pomace (extracted with ethanol or ethyl acetate) or its anthocyanins and flavonols and stimulated by either lipopolysaccharide (LPS) or interferon-γ (IFNγ). Reactive oxygen species (ROS) and nitric oxide (NO) production (indicating oxidative stress and inflammatory response) were measured using the ROS detection reagent DCF-DA and the Griess reaction, respectively. Key findings Analysis of total monomeric anthocyanin (as cyanidin 3-O-glucoside equivalents) indicated five-fold higher amount in the freeze-dried ethanol extract as compared to that of the oven-dried extract; anthocyanin was not detected in the ethyl acetate extracts. Elderberry ethanol extracts (freeze-dried or oven-dried) showed higher anti-oxidant activities and better ability to inhibit LPS or IFNγ-induced NO production as compared with the ethyl acetate extracts. The phenolic compounds strongly inhibited LPS or IFNγ-induced ROS production, but except for quercetin, they were relatively poor in inhibiting NO production. Significance These results demonstrated difference in anti-oxidative and anti-inflammatory effects of elderberry extracts depending on solvents used. Results further identified quercetin as the most active component in suppressing oxidative stress and inflammatory responses on microglial cells. PMID:25744406

  19. Cocaine-mediated microglial activation involves the ER stress-autophagy axis.

    PubMed

    Guo, Ming-Lei; Liao, Ke; Periyasamy, Palsamy; Yang, Lu; Cai, Yu; Callen, Shannon E; Buch, Shilpa

    2015-01-01

    Cocaine abuse leads to neuroinflammation, which, in turn, contributes to the pathogenesis of neurodegeneration associated with advanced HIV-1 infection. Autophagy plays important roles in both innate and adaptive immune responses. However, the possible functional link between cocaine and autophagy has not been explored before. Herein, we demonstrate that cocaine exposure induced autophagy in both BV-2 and primary rat microglial cells as demonstrated by a dose- and time-dependent induction of autophagy-signature proteins such as BECN1/Beclin 1, ATG5, and MAP1LC3B. These findings were validated wherein cocaine treatment of BV-2 cells resulted in increased formation of puncta in cells expressing either endogenous MAP1LC3B or overexpressing GFP-MAP1LC3B. Specificity of cocaine-induced autophagy was confirmed by treating cells with inhibitors of autophagy (3-MA and wortmannin). Intriguingly, cocaine-mediated induction of autophagy involved upstream activation of 2 ER stress pathways (EIF2AK3- and ERN1-dependent), as evidenced by the ability of the ER stress inhibitor salubrinal to ameliorate cocaine-induced autophagy. In vivo validation of these findings demonstrated increased expression of BECN1, ATG5, and MAP1LC3B-II proteins in cocaine-treated mouse brains compared to untreated animals. Increased autophagy contributes to cocaine-mediated activation of microglia since pretreatment of cells with wortmannin resulted in decreased expression and release of inflammatory factors (TNF, IL1B, IL6, and CCL2) in microglial cells. Taken together, our findings suggest that cocaine exposure results in induction of autophagy that is closely linked with neuroinflammation. Targeting autophagic proteins could thus be considered as a therapeutic strategy for the treatment of cocaine-related neuroinflammation diseases. PMID:26043790

  20. Anti-inflammatory mechanism of α-viniferin regulates lipopolysaccharide-induced release of proinflammatory mediators in BV2 microglial cells.

    PubMed

    Dilshara, Matharage Gayani; Lee, Kyoung-Tae; Kim, Hee Ju; Lee, Hak-Ju; Choi, Yung Hyun; Lee, Chang-Min; Kim, Lark Kyun; Kim, Gi-Young

    2014-07-01

    α-Viniferin is an oligostilbene of trimeric resveratrol and has anticancer activity; however, the molecular mechanism underlying the anti-inflammatory effects of α-viniferin has not been completely elucidated thus far. Therefore, we determined the mechanism by which α-viniferin regulates lipopolysaccharide (LPS)-induced expression of proinflammatory mediators in BV2 microglial cells. Treatment with α-viniferin isolated from Clematis mandshurica decreased LPS-induced production of nitric oxide (NO) and prostaglandin E2 (PGE2). α-Viniferin also downregulated the LPS-induced expression of proinflammatory genes such as iNOS and COX-2 by suppressing the activity of nuclear factor kappa B (NF-κB) via dephosphorylation of Akt/PI3K. Treatment with a specific NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC), indirectly showed that NF-κB is a crucial transcription factor for expression of these genes in the early stage of inflammation. Additionally, our results indicated that α-viniferin suppresses NO and PGE2 production in the late stage of inflammation through induction of heme oxygenase-1 (HO-1) regulated by nuclear factor erythroid 2-related factor (Nrf2). Taken together, our data indicate that α-viniferin suppresses the expression of proinflammatory genes iNOS and COX-2 in the early stage of inflammation by inhibiting the Akt/PI3K-dependent NF-κB activation and inhibits the production of proinflammatory mediators NO and PGE2 in the late stage by stimulating Nrf2-mediated HO-1 signaling pathway in LPS-stimulated BV2 microglial cells. These results suggest that α-viniferin may be a potential candidate to regulate LPS-induced inflammation. PMID:24859013

  1. Methamphetamine activates nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and induces human immunodeficiency virus (HIV) transcription in human microglial cells

    PubMed Central

    Wires, Emily S.; Alvarez, David; Dobrowolski, Curtis; Wang, Yun; Morales, Marisela; Karn, Jonathan; Harvey, Brandon K.

    2012-01-01

    Human immunodeficiency virus (HIV) primarily infects glial cells in the central nervous system (CNS). Recent evidence suggests that HIV-infected individuals who abuse drugs such as methamphetamine (METH) have higher viral loads and experience more severe neurological complications than HIV-infected individuals who do not abuse drugs. The aim of this study was to determine the effect of METH on HIV expression from the HIV long terminal repeats (LTR) promoter and on an HIV integrated provirus in microglial cells, the primary host cells for HIV in the CNS. Primary human microglial cells immortalized with SV40 T-antigen (CHME-5 cells) were co-transfected with an HIV LTR reporter and the HIV Tat gene, a key regulator of viral replication and gene expression, and exposed to METH. Our results demonstrate that METH treatment induced LTR activation, an effect potentiated in the presence of Tat. We also found that METH increased the nuclear translocation of the nuclear factor kappa B (NF-κB), a key cellular transcriptional regulator of the LTR promoter, and the activity of an NF-κB-specific reporter plasmid in CHME-5 cells. The presence of a dominant-negative regulator of NF-κB blocked METH-related activation of the HIV LTR. Furthermore, treatment of HIV-latently infected CHME-5 (CHME-5/HIV) cells with METH induced HIV expression in a dose-dependent manner, and nuclear translocation of the p65 subunit of NF-κB. These results suggest that METH can stimulate HIV gene expression in microglia cells through activation of the NF-κB signaling pathway. This mechanism may outline the initial biochemical events leading to the observed increased neurodegeneration in HIV-positive individuals who use METH. PMID:22618514

  2. Neurotoxicity effects of atrazine-induced SH-SY5Y human dopaminergic neuroblastoma cells via microglial activation.

    PubMed

    Ma, Kun; Wu, Hao-Yu; Zhang, Bo; He, Xi; Li, Bai-Xiang

    2015-11-01

    Atrazine (2-chloro-4-ethytlamino-6-isopropylamine-1,3,5-triazine; ATR) is a broad-spectrum herbicide with a wide range of applications worldwide. However, ATR is neurotoxic; it reduces dopamine levels in the substantia nigra and corpus striatum in the midbrain, affects the absorption of synaptic vesicles and synaptic bodies, and interferes with dopamine storage and uptake in synaptic vesicles, leading to neurodegenerative disorders. Microglia are resident immunocompetent and phagocytic cells that regulate and participate in the microenvironment in the central nervous system. They demonstrate macrophage characteristics after activation by releasing inflammatory cytokines and neurotoxic substances to increase the inflammatory response, and are thus involved in neurodegeneration. The aim of this study was to investigate the neurotoxic effects of ATR-activated microglia-mediated neuronal damage in terms of human dopaminergic neuroblastoma SH-SY5Y cell death. ATR was administered to BV-2 microglial cells at 12.5, 25, and 50 μM for 1, 6, 12, 24 and 48 h, respectively. ATR increased activated-microglia-induced overexpression of reactive oxygen species, inducible nitric oxide synthase, nitric oxide, gp91(phox), p47(phox), and the inflammatory cytokines tumor necrosis factor α and interleukin-1β, thus reducing SH-SY5Y cell viability. These results suggest that activated microglia may play a critical role in inflammation-mediated dopaminergic neuronal death, and provide the basis for further studies on the mechanisms of ATR-induced dopaminergic system toxicity. PMID:26256823

  3. The NALP3 inflammasome is involved in neurotoxic prion peptide-induced microglial activation

    PubMed Central

    2012-01-01

    Background Prion diseases are neurodegenerative disorders characterized by the accumulation of an abnormal disease-associated prion protein, PrPSc. In prion-infected brains, activated microglia are often present in the vicinity of PrPSc aggregates, and microglial activation is thought to play a key role in the pathogenesis of prion diseases. Although interleukin (IL)-1β release by prion-induced microglia has been widely reported, the mechanism by which primed microglia become activated and secrete IL-1β in prion diseases has not yet been elucidated. In this study, we investigated the role of the NACHT, LRR and PYD domains-containing protein (NALP)3 inflammasome in IL-1β release from lipopolysaccharide (LPS)-primed microglia after exposure to a synthetic neurotoxic prion fragment (PrP106-126). Methods The inflammasome components NALP3 and apoptosis-associated speck-like protein (ASC) were knocked down by gene silencing. IL-1β production was assessed using ELISA. The mRNA expression of NALP3, ASC, and pro-inflammatory factors was measured by quantitative PCR. Western blot analysis was used to detect the protein level of NALP3, ASC, caspase-1 and nuclear factor-κB. Results We found that that PrP106-126-induced IL-1β release depends on NALP3 inflammasome activation, that inflammasome activation is required for the synthesis of pro-inflammatory and chemotactic factors by PrP106-126-activated microglia, that inhibition of NF-κB activation abrogated PrP106-126-induced NALP3 upregulation, and that potassium efflux and production of reactive oxygen species were implicated in PrP106-126-induced NALP3 inflammasome activation in microglia. Conclusions We conclude that the NALP3 inflammasome is involved in neurotoxic prion peptide-induced microglial activation. To our knowledge, this is the first time that strong evidence for the involvement of NALP3 inflammasome in prion-associated inflammation has been found. PMID:22531291

  4. Glioma associated microglial MMP9 expression is up regulated by TLR2 signalling and sensitive to minocycline

    PubMed Central

    Hu, Feng; Ku, Min-Chi; Markovic, Darko; Dzaye, Omar Dildar a; Lehnardt, Seija; Synowitz, Michael; Wolf, Susanne A.; Kettenmann, Helmut

    2014-01-01

    The invasiveness of malignant gliomas is one of the major obstacles in glioma therapy and the reason for the poor survival of patients. Glioma cells infiltrate into the brain parenchyma and thereby escape surgical resection. Glioma associated microglia/macrophages support glioma infiltration into the brain parenchyma by increased expression and activation of extracellular matrix degrading proteases such as matrix-metalloprotease 2, matrix-metalloprotease 9 and membrane-type 1 matrix metalloprotease. In this work we demonstrate that, matrix-metalloprotease 9 is predominantly expressed by glioma associated microglia/macrophages in mouse and human glioma tissue but not by the glioma cells. Supernatant from glioma cells induced the expression of matrix-metalloprotease 9 in cultured microglial cells. Using mice deficient for different Toll-like receptors we identified Toll-like receptor 2/6 as the signalling pathway for the glioma induced upregulation of microglial matrix-metalloprotease 9. Also in an experimental mouse glioma model, Toll-like receptor 2 deficiency attenuated the upregulation of microglial matrix-metalloprotease 9. Moreover, glioma supernatant triggered an upregulation of Toll-like receptor 2 expression in microglia. Both, the upregulation of matrix-metalloprotease 9 and Toll-like receptor 2 were attenuated by the antibiotic minocycline and a p38 mitogen activated protein kinase antagonist in vitro. Minocycline also extended the survival rate of glioma bearing mice when given to the drinking water. Thus glioma cells change the phenotype of glioma associated microglia/macrophages in a complex fashion using Toll-like receptor 2 as an important signalling pathway and minocycline further proved to be a potential candidate for adjuvant glioma therapy. PMID:24752463

  5. Anesthetic isoflurane attenuates activated microglial cytokine-induced VSC4.1 motoneuronal apoptosis

    PubMed Central

    Yang, Shuangmei; Liu, Jun; Zhang, Xiaoran; Tian, Jianmin; Zuo, Zhichao; Liu, Jingjing; Yue, Xiuqin

    2016-01-01

    Isoflurane (ISO) exhibits neuroprotective effects against inflammation and apoptosis. However, the role of ISO in motoneuronal apoptosis induced by activated microglia remains poorly studied. We investigated the protective effects of ISO on the apoptosis of ventral spinal cord 4.1 (VSC4.1) motoneurons induced by lipopolysaccharide (LPS)-activated BV-2 microglia. Results indicated that ISO inhibited NF-κB activation and pro-inflammatory cytokine release in LPS-treated BV-2 microglia. Conditioned medium (CM) from activated BV-2 cells treated by ISO directly prevented VSC4.1 motoneurons from LPS-CM-induced neuronal apoptosis, as determined by the following: reductions in caspase-8, caspase-9, and caspase-3 activities; downregulation of pro-apoptotic procaspase-8, cleaved (cl)-caspase-8, procaspase-9, cl-caspase-9, caspase-3, cl-caspase-3, Bid, Bax, and cytochrome c expression; and upregulation of anti-apoptotic Bcl-2 expression in LPS-CM-cultured VSC4.1 motoneurons. Findings demonstrated that ISO inhibits BV-2 microglia activation and alleviates VSC4.1 motoneuronal apoptosis induced by microglial activation. These effects suggest that ISO can be used as an alternative agent for reducing neuronal apoptosis. PMID:27186270

  6. Isoflurane attenuates mouse microglial engulfment induced by lipopolysaccharide and interferon-γ possibly by inhibition of p38 mitogen-activated protein kinase.

    PubMed

    Ryu, Jung-Hee; Wang, Zhi; Fan, Dan; Han, Sung-Hee; Do, Sang-Hwan; Zuo, Zhiyi

    2016-09-28

    Microglial engulfment is a basic function to clean up dead and injured cells and invaders, such as bacteria. This study was designed to assess the effects of isoflurane on the microglial engulfment induced by lipopolysaccharide (LPS) plus interferon-γ (IFN-γ) and the involvement of p38 mitogen-activated protein kinase (MAPK) in these effects. C8-B4 microglial cells were exposed to 1, 2, and 3% isoflurane at 2 h after the initiation of LPS (100 ng/ml) and IFN-γ (1 ng/ml) stimulation. Fluorescent immunostaining was performed to assess the percentage of cells with engulfment of fluorescent microspheres after stimulation for 24 h. P38 and phosphorylated p38 were determined by Western blotting. Isoflurane concentration dependently decreased microglial engulfment stimulated by LPS and IFN-γ. LPS and IFN-γ increased the phosphorylated p38 in microglial cells. This upregulation was decreased by isoflurane. SB203580, a p38 MAPK inhibitor, abolished the LPS-induced and IFN-γ-induced increase of engulfment activity, whereas anisomycin, a p38 MAPK activator, partly reversed the isoflurane-decreased microglial engulfment activity. These results suggest that isoflurane reduces LPS-induced and IFN-γ-induced microglial engulfment and that these effects may be mediated by inhibiting p38 MAPK. PMID:27513199

  7. Astrocyte and microglial activation in the lateral geniculate nucleus and visual cortex of glaucomatous and optic nerve transected primates

    PubMed Central

    Lam, Dawn; Jim, Janey; To, Eleanor; Rasmussen, Carol; Kaufman, Paul L.

    2009-01-01

    Purpose To examine early cellular changes, including astrocyte reactivity and microglial activation, in the central nervous system (CNS) after unilateral optic nerve transection (ONT) or ocular hypertension (OHT) in monkeys. Methods Unilateral ONT or OHT was achieved in monkeys for periods ranging from two weeks to two months in duration. After intracardial perfusion, sections of the lateral geniculate nucleus (LGN) and visual cortex (V1) were examined by immunohistochemistry for glial fibrillary acidic protein (GFAP) and CD11b, a subunit of the complement 3 receptor and marker of macrophage and microglia cells (MAC-1). Alternate serial sections were evaluated by cytochrome oxidase (CO) histochemistry to assess metabolic activity. Results Both ONT and OHT caused a reduction in metabolic activity in the treated eye layers of the LGN and V1. GFAP and MAC-1 immunoreactivities were elevated in spatial register with the treated eye layers of the LGN and V1 in ONT animals. In the OHT animals, GFAP, but not MAC-1, immunoreactivity was elevated in spatial register with the treated eye layers of LGN and V1. Thus, during the first weeks after OHT or ONT, loss of metabolic activity was accompanied by astrocyte and microglial activation in the ONT group and astrocyte activation in the OHT animals. Conclusions These results suggest that unilateral OHT or ONT triggers separate signaling pathways that promote differential activation of CNS glial populations. Astrocyte reactivity was present in all brains studied and demonstrates the loss of metabolic activity is accompanied by increased GFAP immunoreactivity. Microglial activation was only observed in ONT brains. The lack of microglial activation as late as two months following OHT may represent a time window for early treatment to prevent long-term neuronal loss in the CNS after OHT. PMID:19898640

  8. Hypoxia induced amoeboid microglial cell activation in postnatal rat brain is mediated by ATP receptor P2X4

    PubMed Central

    2011-01-01

    Background Activation of amoeboid microglial cells (AMC) and its related inflammatory response have been linked to the periventricular white matter damage after hypoxia in neonatal brain. Hypoxia increases free ATP in the brain and then induces various effects through ATP receptors. The present study explored the possible mechanism in ATP induced AMC activation in hypoxia. Results We first examined the immunoexpression of P2X4, P2X7 and P2Y12 in the corpus callosum (CC) and subependyma associated with the lateral ventricles where both areas are rich in AMC. Among the three purinergic receptors, P2X4 was most intensely expressed. By double immunofluorescence, P2X4 was specifically localized in AMC (from P0 to P7) but the immunofluorescence in AMC was progressively diminished with advancing age (P14). It was further shown that P2X4 expression was noticeably enhanced in P0 day rats subjected to hypoxia and killed at 4, 24, 72 h and 7 d versus their matching controls by double labeling and western blotting analysis. P2X4 expression was most intense at 7 d whence the inflammatory response was drastic after hypoxia. We then studied the association of P2X4 with cytokine release in AMC after hypoxic exposure. In primary microglial cells exposed to hypoxia, IL-1β and TNF-α protein levels were up-regulated. Blockade of P2X4 receptor with 2', 3'-0-(2, 4, 6-Trinitrophenyl) adenosine 5'-triphosphate, a selective P2X1-7 blocker resulted in partial suppression of IL-1β (24% vs hypoxic group) and TNF-α expression (40% vs hypoxic group). However, pyridoxal phosphate-6-azo (benzene-2, 4-disulfonic acid) tetrasodium salt hydrate, a selective P2X1-3, 5-7 blocker did not exert any significant effect on the cytokine expression. Conclusions It is concluded that P2X4 which is constitutively expressed by AMC in postnatal rats was enhanced in hypoxia. Hypoxia induced increase in IL-1β and TNF-α expression was reversed by 2', 3'-0-(2, 4, 6-Trinitrophenyl) adenosine 5'-triphosphate

  9. Proinflammatory-activated glioma cells induce a switch in microglial polarization and activation status, from a predominant M2b phenotype to a mixture of M1 and M2a/B polarized cells

    PubMed Central

    Lisi, Lucia; Stigliano, Egidio; Lauriola, Libero; Navarra, Pierluigi; Russo, Cinzia Dello

    2014-01-01

    Malignant gliomas are primary brain tumors characterized by morphological and genetic complexities, as well as diffuse infiltration into normal brain parenchyma. Within gliomas, microglia/macrophages represent the largest tumor-infiltrating cell population, contributing by at least one-third to the total tumor mass. Bi-directional interactions between glioma cells and microglia may therefore play an important role on tumor growth and biology. In the present study, we have characterized the influence of glioma-soluble factors on microglial function, comparing the effects of media harvested under basal conditions with those of media obtained after inducing a pro-inflammatory activation state in glioma cells. We found that microglial cells undergo a different pattern of activation depending on the stimulus; in the presence of activated glioma-derived factors, i.e. a condition mimicking the late stage of pathology, microglia presents as a mixture of polarization phenotypes (M1 and M2a/b), with up-regulation of iNOS (inducible nitric oxide synthase), ARG (arginase) and IL (interleukine)-10. At variance, microglia exposed to basal glioma-derived factors, i.e. a condition resembling the early stage of pathology, shows a more specific pattern of activation, with increased M2b polarization status and up-regulation of IL-10 only. As far as viability and cell proliferation are concerned, both LI-CM [LPS (lipopolysaccharide)–IFNγ (interferon γ) conditioned media] and C-CM (control-conditioned media) induce similar effects on microglial morphology. Finally, in human glioma tissue obtained from surgical resection of patients with IV grade glioblastoma, we detected a significant amount of CD68 positive cells, which is a marker of macrophage/microglial phagocytic activity, suggesting that in vitro findings presented here might have a relevance in the human pathology as well. PMID:24689533

  10. Prothrombin kringle-2 induces death of mesencephalic dopaminergic neurons in vivo and in vitro via microglial activation.

    PubMed

    Kim, Sang Ryong; Chung, Eun Sook; Bok, Eugene; Baik, Hyung Hwan; Chung, Young Cheul; Won, So Yoon; Joe, Eunhye; Kim, Tae Hyong; Kim, Soung Soo; Jin, Min Young; Choi, Sang Ho; Jin, Byung Kwan

    2010-05-15

    We have shown that prothrombin kringle-2 (pKr-2), a domain of human prothrombin distinct from thrombin could activate cultured rat brain microglia in vitro. However, little is known whether pKr-2-induced microglial activation could cause neurotoxicity on dopaminergic (DA) neurons in vivo. To address this question, pKr-2 was injected into the rat substantia nigra (SN). Tyrosine hydroxylase (TH) immunohistochemistry experiments demonstrate significant loss of DA neurons seven days after injection of pKr-2. In parallel, pKr-2-activated microglia were detected in the SN with OX-42 and OX-6 immunohistochemistry. Reverse transcription PCR and double-label immunohistochemistry revealed that activated microglia in vivo exhibit early and transient expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and several proinflammatory cytokines. The pKr-2-induced loss of SN DA neurons was partially inhibited by the NOS inhibitor N(G)-nitro-L-arginine methyl ester hydrochloride, and the COX-2 inhibitor DuP-697. Extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase and p38 mitogen-activated protein kinase were activated in the SN as early as 1 hr after pKr-2 injection, and localized within microglia. Inhibition of these kinases led to attenuation of mRNA expression of iNOS, COX-2 and several proinflammatory cytokines, and rescue of DA neurons in the SN. Intriguingly, following treatment with pKr-2 in vitro, neurotoxicity was detected exclusively in co-cultures of mesencephalic neurons and microglia, but not microglia-free neuron-enriched mesencephalic cultures, indicating that microglia are required for pKr-2 neurotoxicity. Our results strongly suggest that microglia activated by endogenous compound(s), such as pKr-2, are implicated in the DA neuronal cell death in the SN. PMID:20025058

  11. Blueberry Opposes β-Amyloid Peptide-Induced Microglial Activation Via Inhibition of p44/42 Mitogen-Activation Protein Kinase

    PubMed Central

    Zhu, Yuyan; Bickford, Paula C.; Sanberg, Paul; Giunta, Brian

    2008-01-01

    Abstract Alzheimer's Disease (AD) is the most common age-related dementia, with a current prevalence in excess of five million individuals in the United States. The aggregation of amyloid-beta (Aβ) into fibrillar amyloid plaques is a key pathological event in the development of the disease. Microglial proinflammatory activation is widely known to cause neuronal and synaptic damage that correlates with cognitive impairment in AD. However, current pharmacological attempts at reducing neuroinflammation mediated via microglial activation have been largely negative in terms of slowing AD progression. Previously, we have shown that microglia express proinflammatory cytokines and a reduced capacity to phagocytose Aβ in the context of CD40, Aβ peptides and/or lipopolysaccharide (LPS) stimulation, a phenomenon that can be opposed by attenuation of p44/42 mitogen-activated protein kinase (MAPK) signaling. Other groups have found that blueberry (BB) extract both inhibits phosphorylation of this MAPK module and also improves cognitive deficits in AD model mice. Given these considerations and the lack of reduced Aβ quantities in behaviorally improved BB-fed mice, we wished to determine whether BB supplementation would alter the microglial proinflammatory activation state in response to Aβ. We found that BB significantly enhances microglial clearance of Aβ, inhibits aggregation of Aβ1–42, and suppresses microglial activation, all via suppression of the p44/42 MAPK module. Thus, these data may explain the previously observed behavioral recovery in PSAPP mice and suggest a means by which dietary supplementation could mitigate an undesirable microglial response toward fibrillar Aβ. PMID:18789000

  12. Microglial cell activation is a source of metalloproteinase generation during hemorrhagic transformation

    PubMed Central

    del Zoppo, Gregory J; Frankowski, Harald; Gu, Yu-Huan; Osada, Takashi; Kanazawa, Masato; Milner, Richard; Wang, Xiaoyun; Hosomi, Naohisa; Mabuchi, Takuma; Koziol, James A

    2012-01-01

    Hemorrhage and edema accompany evolving brain tissue injury after ischemic stroke. In patients, these events have been associated with metalloproteinase (MMP)-9 in plasma. Both the causes and cellular sources of MMP-9 generation in this setting have not been defined. MMP-2 and MMP-9 in nonhuman primate tissue in regions of plasma leakage, and primary murine microglia and astrocytes, were assayed by immunocytochemistry, zymography, and real-time RT-PCR. Ischemia-related hemorrhage was associated with microglial activation in vivo, and with the leakage of plasma fibronectin and vitronectin into the surrounding tissue. In strict serum-depleted primary cultures, by zymography, pro-MMP-9 was generated by primary murine microglia when exposed to vitronectin and fibronectin. Protease secretion was enhanced by experimental ischemia (oxygen-glucose deprivation, OGD). Primary astrocytes, on each matrix, generated only pro-MMP-2, which decreased during OGD. Microglia–astrocyte contact enhanced pro-MMP-9 generation in a cell density-dependent manner under normoxia and OGD. Compatible with observations in a high quality model of focal cerebral ischemia, microglia, but not astrocytes, respond to vitronectin and fibronectin, found when plasma extravasates into the injured region. Astrocytes alone do not generate pro-MMP-9. These events explain the appearance of MMP-9 antigen in association with ischemia-induced cerebral hemorrhage and edema. PMID:22354151

  13. Spontaneously hypertensive rats display reduced microglial activation in response to ischemic stroke and lipopolysaccharide

    PubMed Central

    2012-01-01

    Background For successful translation to clinical stroke studies, the Stroke Therapy Academic Industry Round Table criteria have been proposed. Two important criteria are testing of therapeutic interventions in conscious animals and the presence of a co-morbidity factor. We chose to work with hypertensive rats since hypertension is an important modifiable risk factor for stroke and influences the clinical outcome. We aimed to compare the susceptibility to ischemia in hypertensive rats with those in normotensive controls in a rat model for induction of ischemic stroke in conscious animals. Methods The vasoconstrictor endothelin-1 was stereotactically applied in the vicinity of the middle cerebral artery of control Wistar Kyoto rats (WKYRs) and Spontaneously Hypertensive rats (SHRs) to induce a transient decrease in striatal blood flow, which was measured by the Laser Doppler technique. Infarct size was assessed histologically by Cresyl Violet staining. Sensory-motor functions were measured at several time points using the Neurological Deficit Score. Activation of microglia and astrocytes in the striatum and cortex was investigated by immunohistochemistry using antibodies against CD68/Iba-1 and glial fibrillary acidic protein. Results and conclusions The SHRs showed significantly larger infarct volumes and more pronounced sensory-motor deficits, compared to the WKYRs at 24 h after the insult. However, both differences disappeared between 24 and 72 h. In SHRs, microglia were less susceptible to activation by lipopolysaccharide and there was a reduced microglial activation after induction of ischemic stroke. These quantitative and qualitative differences may be relevant for studying the efficacy of new treatments for stroke in accordance to the Stroke Therapy Academic Industry Round Table criteria. PMID:22647642

  14. Monocyte and microglial activation in patients with mood-stabilized bipolar disorder

    PubMed Central

    Jakobsson, Joel; Bjerke, Maria; Sahebi, Sara; Isgren, Anniella; Ekman, Carl Johan; Sellgren, Carl; Olsson, Bob; Zetterberg, Henrik; Blennow, Kaj; Pålsson, Erik; Landén, Mikael

    2015-01-01

    Background Bipolar disorder is associated with medical comorbidities that have been linked to systemic inflammatory mechanisms. There is, however, limited evidence supporting a role of neuroinflammation in bipolar disorder. Here we tested whether microglial activation and associated tissue remodelling processes are related to bipolar disorder by analyzing markers in cerebrospinal fluid (CSF) and serum from patients and healthy controls. Methods Serum was sampled from euthymic patients with bipolar disorder and healthy controls, and CSF was sampled from a large subset of these individuals. The levels of monocyte chemoattractant protein-1 (MCP-1), YKL-40, soluble cluster of differentiation 14 (sCD14), tissue inhibitor of metalloproteinases-1 (TIMP-1) and tissue inhibitor of metalloproteinases-2 (TIMP-2), were measured, and we adjusted comparisons between patients and controls for confounding factors. Results We obtained serum samples from 221 patients and 112 controls and CSF samples from 125 patients and 87 controls. We found increased CSF levels of MCP-1 and YKL-40 and increased serum levels of sCD14 and YKL-40 in patients compared with controls; these differences remained after controlling for confounding factors, such as age, sex, smoking, blood–CSF barrier function, acute-phase proteins and body mass index. The CSF levels of MCP-1 and YKL-40 correlated with the serum levels, whereas the differences between patients and controls in CSF levels of MCP-1 and YKL-40 were independent of serum levels. Limitations The cross-sectional study design precludes conclusions about causality. Conclusion Our results suggest that both neuroinflammatory and systemic inflammatory processes are involved in the pathophysiology of bipolar disorder. Importantly, markers of immunological processes in the brain were independent of peripheral immunological activity. PMID:25768030

  15. Microglial Kv1.3 Channels and P2Y12 Receptors Differentially Regulate Cytokine and Chemokine Release from Brain Slices of Young Adult and Aged Mice

    PubMed Central

    Eder, Claudia

    2015-01-01

    Brain tissue damage following stroke or traumatic brain injury is accompanied by neuroinflammatory processes, while microglia play a central role in causing and regulating neuroinflammation via production of proinflammatory substances, including cytokines and chemokines. Here, we used brain slices, an established in situ brain injury model, from young adult and aged mice to investigate cytokine and chemokine production with particular focus on the role of microglia. Twenty four hours after slice preparation, higher concentrations of proinflammatory cytokines, i.e. TNF-α and IL-6, and chemokines, i.e. CCL2 and CXCL1, were released from brain slices of aged mice than from slices of young adult mice. However, maximal microglial stimulation with LPS for 24 h did not reveal age-dependent differences in the amounts of released cytokines and chemokines. Mechanisms underlying microglial cytokine and chemokine production appear to be similar in young adult and aged mice. Inhibition of microglial Kv1.3 channels with margatoxin reduced release of IL-6, but not release of CCL2 and CXCL1. In contrast, blockade of microglial P2Y12 receptors with PSB0739 inhibited release of CCL2 and CXCL1, whereas release of IL-6 remained unaffected. Cytokine and chemokine production was not reduced by inhibitors of Kir2.1 K+ channels or adenosine receptors. In summary, our data suggest that brain tissue damage-induced production of cytokines and chemokines is age-dependent, and differentially regulated by microglial Kv1.3 channels and P2Y12 receptors. PMID:26011191

  16. Crocin Upregulates CX3CR1 Expression by Suppressing NF-κB/YY1 Signaling and Inhibiting Lipopolysaccharide-Induced Microglial Activation.

    PubMed

    Lv, Bochang; Huo, Fuquan; Zhu, Zhongqiao; Xu, Zhiguo; Dang, Xiaojie; Chen, Tao; Zhang, Ting; Yang, Xinguang

    2016-08-01

    Glaucoma is a group of neurodegenerative diseases characterized by the progressive loss of retinal ganglion cells (RGCs) and optic nerve fibers. Microglial activation has been shown to be deleterious to RGCs and may participate in the progression of glaucoma. Crocin, one of the major active ingredients in saffron, has been found to inhibit microglial activation. However, the mechanism remains unclear. The aim of this study was to investigate whether crocin can inhibit lipopolysaccharide (LPS)-induced microglial activation and to clarify the mechanisms involved. The influence of crocin on primary RGCs and LPS-stimulated BV2 microglial cells survival was determined by the MTT and lactate dehydrogenase assays, or by flow cytometry. BV2 cells were pretreated with various concentrations of crocin for 2 h followed by 1 μg/mL LPS stimulation. Microglial markers and pro-inflammatory mediators were assessed by real-time PCR, western blot and ELISA. Furthermore, CX3CR1 expression was detected and the underlying mechanism was examined. The concentrations of crocin ranged from 0.1 to 1 μM, and did not show any cytotoxicity in RGC and BV2 cells. After crocin pretreatment, the expression of microglial markers (CD11b and Iba-1) and pro-inflammatory mediators (iNOS, COX-2, IL-1β, and TNF-α) induced by LPS were significantly decreased in a dose-dependent manner. Additionally, CX3CR1 expression was remarkably increased by crocin via the suppression of NF-κB/Yin Yang 1 (YY1) signaling in BV2 cells. In conclusion, crocin effectively suppresses microglial activation and upregulates CX3CR1 expression by suppressing NF-κB/YY1 signaling. PMID:27084772

  17. Sleep Deprivation Aggravates Median Nerve Injury-Induced Neuropathic Pain and Enhances Microglial Activation by Suppressing Melatonin Secretion

    PubMed Central

    Huang, Chun-Ta; Chiang, Rayleigh Ping-Ying; Chen, Chih-Li; Tsai, Yi-Ju

    2014-01-01

    Study Objectives: Sleep deprivation is common in patients with neuropathic pain, but the effect of sleep deprivation on pathological pain remains uncertain. This study investigated whether sleep deprivation aggravates neuropathic symptoms and enhances microglial activation in the cuneate nucleus (CN) in a median nerve chronic constriction injury (CCI) model. Also, we assessed if melatonin supplements during the sleep deprived period attenuates these effects. Design: Rats were subjected to sleep deprivation for 3 days by the disc-on-water method either before or after CCI. In the melatonin treatment group, CCI rats received melatonin supplements at doses of 37.5, 75, 150, or 300 mg/kg during sleep deprivation. Melatonin was administered at 23:00 once a day. Participants: Male Sprague-Dawley rats, weighing 180-250 g (n = 190), were used. Measurements: Seven days after CCI, behavioral testing was conducted, and immunohistochemistry, immunoblotting, and enzyme-linked immunosorbent assay were used for qualitative and quantitative analyses of microglial activation and measurements of proinflammatory cytokines. Results: In rats who underwent post-CCI sleep deprivation, microglia were more profoundly activated and neuropathic pain was worse than those receiving pre-CCI sleep deprivation. During the sleep deprived period, serum melatonin levels were low over the 24-h period. Administration of melatonin to CCI rats with sleep deprivation significantly attenuated activation of microglia and development of neuropathic pain, and markedly decreased concentrations of proinflammatory cytokines. Conclusions: Sleep deprivation makes rats more vulnerable to nerve injury-induced neuropathic pain, probably because of associated lower melatonin levels. Melatonin supplements to restore a circadian variation in melatonin concentrations during the sleep deprived period could alleviate nerve injury-induced behavioral hypersensitivity. Citation: Huang CT, Chiang RP, Chen CL, Tsai YJ. Sleep

  18. Anti-inflammatory effects of thymoquinone in activated BV-2 microglial cells.

    PubMed

    Taka, Equar; Mazzio, Elizabeth A; Goodman, Carl B; Redmon, Natalie; Flores-Rozas, Hernan; Reams, Renee; Darling-Reed, Selina; Soliman, Karam F A

    2015-09-15

    Thymoquinone (TQ), the main pharmacological active ingredient within the black cumin seed (Nigella sativa) is believed to be responsible for the therapeutic effects on chronic inflammatory conditions such as arthritis, asthma and neurodegeneration. In this study, we evaluated the potential anti-inflammatory role of TQ in lipopolysaccharide (LPS)-stimulated BV-2 murine microglia cells. The results obtained indicate that TQ was effective in reducing NO2(-) with an IC50 of 5.04μM, relative to selective iNOS inhibitor LNIL-l-N6-(1-iminoethyl)lysine (IC50 4.09μM). TQ mediated reduction in NO2(-) was found to parallel the decline of iNOS protein expression as confirmed by immunocytochemistry. In addition, we evaluated the anti-inflammatory effects of TQ on ninety-six (96) cytokines using a RayBio AAM-CYT-3 and 4 cytokine antibody protein array. Data obtained establish a baseline protein expression profile characteristic of resting BV-2 cells in the order of osteopontin>MIP-1alpha>MIP-1g>IGF-1 and MCP-I. In the presence of LPS [1ug/ml], activated BV-2 cells produced a sharp rise in specific pro-inflammatory cytokines/chemokine's IL-6, IL-12p40/70, CCL12 /MCP-5, CCL2/MCP-1, and G-CSF which were attenuated by the addition of TQ (10μM). The TQ mediated attenuation of MCP-5, MCP-1 and IL-6 protein in supernatants from activated BV-2 cells were corroborated by independent ELISA. Moreover, the data obtained from the RT(2) PCR demonstrated a similar pattern where the LPS mediated elevation of mRNA for IL-6, CCL12/MCP-5, CCL2/MCP-1 were significantly attenuated by TQ (10μM). Also, in this study, consistent data were obtained for both protein antibody array densitometry and ELISA assays. In addition, TQ was found to reduce LPS mediated elevation in gene expression of Cxcl10 and a number of other cytokines in the panel. These findings demonstrate the significant anti-inflammatory properties of TQ in LPS activated microglial cells. Therefore, the obtained results might indicate

  19. Glucocerebrosidase 1 deficient Danio rerio mirror key pathological aspects of human Gaucher disease and provide evidence of early microglial activation preceding alpha-synuclein-independent neuronal cell death

    PubMed Central

    Keatinge, Marcus; Bui, Hai; Menke, Aswin; Chen, Yu-Chia; Sokol, Anna M.; Bai, Qing; Ellett, Felix; Da Costa, Marc; Burke, Derek; Gegg, Matthew; Trollope, Lisa; Payne, Thomas; McTighe, Aimee; Mortiboys, Heather; de Jager, Sarah; Nuthall, Hugh; Kuo, Ming-Shang; Fleming, Angeleen; Schapira, Anthony H.V.; Renshaw, Stephen A.; Highley, J. Robin; Chacinska, Agnieszka; Panula, Pertti; Burton, Edward A.; O'Neill, Michael J.; Bandmann, Oliver

    2015-01-01

    Autosomal recessively inherited glucocerebrosidase 1 (GBA1) mutations cause the lysosomal storage disorder Gaucher's disease (GD). Heterozygous GBA1 mutations (GBA1+/−) are the most common risk factor for Parkinson's disease (PD). Previous studies typically focused on the interaction between the reduction of glucocerebrosidase (enzymatic) activity in GBA1+/− carriers and alpha-synuclein-mediated neurotoxicity. However, it is unclear whether other mechanisms also contribute to the increased risk of PD in GBA1+/− carriers. The zebrafish genome does not contain alpha-synuclein (SNCA), thus providing a unique opportunity to study pathogenic mechanisms unrelated to alpha-synuclein toxicity. Here we describe a mutant zebrafish line created by TALEN genome editing carrying a 23 bp deletion in gba1 (gba1c.1276_1298del), the zebrafish orthologue of human GBA1. Marked sphingolipid accumulation was already detected at 5 days post-fertilization with accompanying microglial activation and early, sustained up-regulation of miR-155, a master regulator of inflammation. gba1c.1276_1298del mutant zebrafish developed a rapidly worsening phenotype from 8 weeks onwards with striking reduction in motor activity by 12 weeks. Histopathologically, we observed marked Gaucher cell invasion of the brain and other organs. Dopaminergic neuronal cell count was normal through development but reduced by >30% at 12 weeks in the presence of ubiquitin-positive, intra-neuronal inclusions. This gba1c.1276_1298del zebrafish line is the first viable vertebrate model sharing key pathological features of GD in both neuronal and non-neuronal tissue. Our study also provides evidence for early microglial activation prior to alpha-synuclein-independent neuronal cell death in GBA1 deficiency and suggests upregulation of miR-155 as a common denominator across different neurodegenerative disorders. PMID:26376862

  20. Activation of glucocorticoid receptors in Müller glia is protective to retinal neurons and suppresses microglial reactivity.

    PubMed

    Gallina, Donika; Zelinka, Christopher Paul; Cebulla, Colleen M; Fischer, Andy J

    2015-11-01

    Reactive microglia and macrophages are prevalent in damaged retinas. Glucocorticoid signaling is known to suppress inflammation and the reactivity of microglia and macrophages. In the vertebrate retina, the glucocorticoid receptor (GCR) is known to be activated and localized to the nuclei of Müller glia (Gallina et al., 2014). Accordingly, we investigated how signaling through GCR influences the survival of neurons using the chick retina in vivo as a model system. We applied intraocular injections of GCR agonist or antagonist, assessed microglial reactivity, and the survival of retinal neurons following different damage paradigms. Microglial reactivity was increased in retinas from eyes that were injected with vehicle, and this reactivity was decreased by GCR-agonist dexamethasone (Dex) and increased by GCR-antagonist RU486. We found that activation of GCR suppresses the reactivity of microglia and inhibited the loss of retinal neurons resulting from excitotoxicity. We provide evidence that the protection-promoting effects of Dex were maintained when the microglia were selectively ablated. Similarly, intraocular injections of Dex protected ganglion cells from colchicine-treatment and protected photoreceptors from damage caused by retinal detachment. We conclude that activation of GCR promotes the survival of ganglion cells in colchicine-damaged retinas, promotes the survival of amacrine and bipolar cells in excitotoxin-damaged retinas, and promotes the survival of photoreceptors in detached retinas. We propose that suppression of microglial reactivity is secondary to activation of GCR in Müller glia, and this mode of signaling is an effective means to lessen the damage and vision loss resulting from different types of retinal damage. PMID:26272753

  1. Enriched environment induces beneficial effects on memory deficits and microglial activation in the hippocampus of type 1 diabetic rats.

    PubMed

    Piazza, Francele Valente; Segabinazi, Ethiane; Centenaro, Lígia Aline; do Nascimento, Patrícia Severo; Achaval, Matilde; Marcuzzo, Simone

    2014-03-01

    Type 1 diabetes mellitus (T1DM) has been associated with long-term complications in the central nervous system, causing brain cellular dysfunctions and cognitive deficits. On the other hand, enriched environment (EE) induces experience-dependent plasticity, especially in the hippocampus, improving the performance of animals in learning and memory tasks. Thus, our objective was to investigate the influence of the EE on memory deficits, locomotion, corticosterone levels, synaptophysin (SYP) protein immunoreactivity, cell survival and microglial activation in the dentate gyrus (DG) of T1DM rat hippocampus. Male Wistar rats (21-day-old) were exposed to EE or maintained in standard housing (controls, C) for 3 months. At adulthood, the C and EE animals were randomly divided and diabetes was induced in half of them. All the animals received 4 doses of BrdU, 24 h apart. Hippocampus-dependent spatial memory, general locomotion and serum corticosterone levels were evaluated at the end of the experiment. The animals were transcardially perfused 30 days post-BrdU administration. Our results showed that EE was able to prevent/delay the development of memory deficits caused by diabetes in rats, however it did not revert the motor impairment observed in the diabetic group. SYP immunoreactivity was increased in the enriched healthy group. The EE decreased the serum corticosterone levels in diabetic adult rats and attenuated the injurious microglial activation, though without altering the decrease of the survival cell. Thus, EE was shown to help to ameliorate cognitive comorbidities associated with T1DM, possibly by reducing hyperactivity in the hypothalamic-pituitary-adrenal axis and microglial activation in diabetic animals. PMID:24318482

  2. The Anti-Inflammatory Activity of Eucommia ulmoides Oliv. Bark. Involves NF-κB Suppression and Nrf2-Dependent HO-1 Induction in BV-2 Microglial Cells.

    PubMed

    Kwon, Seung-Hwan; Ma, Shi-Xun; Hwang, Ji-Young; Ko, Yong-Hyun; Seo, Ji-Yeon; Lee, Bo-Ram; Lee, Seok-Yong; Jang, Choon-Gon

    2016-05-01

    In the present study, we investigated the anti-inflammatory properties of Eucommia ulmoides Oliv. Bark. (EUE) in lipopolysaccharide (LPS)-stimulated microglial BV-2 cells and found that EUE inhibited LPS-mediated up-regulation of pro-inflammatory response factors. In addition, EUE inhibited the elevated production of pro-inflammatory cytokines, mediators, and reactive oxygen species (ROS) in LPS-stimulated BV-2 microglial cells. Subsequent mechanistic studies revealed that EUE suppressed LPS-induced phosphorylation of mitogen-activated protein kinases (MAPKs), phosphoinositide-3-kinase (PI3K)/Akt, glycogen synthase kinase-3β (GSK-3β), and their downstream transcription factor, nuclear factor-kappa B (NF-κB). EUE also blocked the nuclear translocation of NF-κB and inhibited its binding to DNA. We next demonstrated that EUE induced the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and upregulated heme oxygenase-1 (HO-1) expression. We determined that the significant up-regulation of HO-1 expression by EUE was a consequence of Nrf2 nuclear translocation; furthermore, EUE increased the DNA binding of Nrf2. In contrast, zinc protoporphyrin (ZnPP), a specific HO-1 inhibitor, blocked the ability of EUE to inhibit NO and PGE₂ production, indicating the vital role of HO-1. Overall, our results indicate that EUE inhibits pro-inflammatory responses by modulating MAPKs, PI3K/Akt, and GSK-3β, consequently suppressing NF-κB activation and inducing Nrf2-dependent HO-1 activation. PMID:27068259

  3. The Anti-Inflammatory Activity of Eucommia ulmoides Oliv. Bark. Involves NF-κB Suppression and Nrf2-Dependent HO-1 Induction in BV-2 Microglial Cells

    PubMed Central

    Kwon, Seung-Hwan; Ma, Shi-Xun; Hwang, Ji-Young; Ko, Yong-Hyun; Seo, Ji-Yeon; Lee, Bo-Ram; Lee, Seok-Yong; Jang, Choon-Gon

    2016-01-01

    In the present study, we investigated the anti-inflammatory properties of Eucommia ulmoides Oliv. Bark. (EUE) in lipopolysaccharide (LPS)-stimulated microglial BV-2 cells and found that EUE inhibited LPS-mediated up-regulation of pro-inflammatory response factors. In addition, EUE inhibited the elevated production of pro-inflammatory cytokines, mediators, and reactive oxygen species (ROS) in LPS-stimulated BV-2 microglial cells. Subsequent mechanistic studies revealed that EUE suppressed LPS-induced phosphorylation of mitogen-activated protein kinases (MAPKs), phosphoinositide-3-kinase (PI3K)/Akt, glycogen synthase kinase-3β (GSK-3β), and their downstream transcription factor, nuclear factor-kappa B (NF-κB). EUE also blocked the nuclear translocation of NF-κB and inhibited its binding to DNA. We next demonstrated that EUE induced the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and upregulated heme oxygenase-1 (HO-1) expression. We determined that the significant up-regulation of HO-1 expression by EUE was a consequence of Nrf2 nuclear translocation; furthermore, EUE increased the DNA binding of Nrf2. In contrast, zinc protoporphyrin (ZnPP), a specific HO-1 inhibitor, blocked the ability of EUE to inhibit NO and PGE2 production, indicating the vital role of HO-1. Overall, our results indicate that EUE inhibits pro-inflammatory responses by modulating MAPKs, PI3K/Akt, and GSK-3β, consequently suppressing NF-κB activation and inducing Nrf2-dependent HO-1 activation. PMID:27068259

  4. Redox Control of Microglial Function: Molecular Mechanisms and Functional Significance

    PubMed Central

    McBean, Gethin; Cindric, Marina; Egea, Javier; López, Manuela G.; Rada, Patricia; Zarkovic, Neven

    2014-01-01

    Abstract Neurodegenerative diseases are characterized by chronic microglial over-activation and oxidative stress. It is now beginning to be recognized that reactive oxygen species (ROS) produced by either microglia or the surrounding environment not only impact neurons but also modulate microglial activity. In this review, we first analyze the hallmarks of pro-inflammatory and anti-inflammatory phenotypes of microglia and their regulation by ROS. Then, we consider the production of reactive oxygen and nitrogen species by NADPH oxidases and nitric oxide synthases and the new findings that also indicate an essential role of glutathione (γ-glutamyl-l-cysteinylglycine) in redox homeostasis of microglia. The effect of oxidant modification of macromolecules on signaling is analyzed at the level of oxidized lipid by-products and sulfhydryl modification of microglial proteins. Redox signaling has a profound impact on two transcription factors that modulate microglial fate, nuclear factor kappa-light-chain-enhancer of activated B cells, and nuclear factor (erythroid-derived 2)-like 2, master regulators of the pro-inflammatory and antioxidant responses of microglia, respectively. The relevance of these proteins in the modulation of microglial activity and the interplay between them will be evaluated. Finally, the relevance of ROS in altering blood brain barrier permeability is discussed. Recent examples of the importance of these findings in the onset or progression of neurodegenerative diseases are also discussed. This review should provide a profound insight into the role of redox homeostasis in microglial activity and help in the identification of new promising targets to control neuroinflammation through redox control of the brain. Antioxid. Redox Signal. 21, 1766–1801. PMID:24597893

  5. Kaempferol acts through mitogen-activated protein kinases and protein kinase B/AKT to elicit protection in a model of neuroinflammation in BV2 microglial cells

    PubMed Central

    Park, SE; Sapkota, K; Kim, S; Kim, H; Kim, SJ

    2011-01-01

    BACKGROUND AND PURPOSE Kaempferol, a dietary flavonoid and phyto-oestrogen, is known to have anti-inflammatory properties. Microglial activation has been implicated in various neurodegenerative diseases. Anti-inflammatory effects of kaempferol and the underlying mechanisms were investigated by using LPS-stimulated microglial BV2 cells. EXPERIMENTAL APPROACH Cell viability was measured using MTT and neutral red assays. elisa, Western blot, immunocytochemistry and electrophoretic mobility-shift assay were used to analyse NO, PGE2, TNF-α and IL-1β production, inducible NOS (iNOS), COX-2 expression and the involvement of signalling pathways such as toll-like receptor-4 (TLR4), MAPK cascades, PKB (AKT) and NF-κB. Accumulation of reaction oxygen species (ROS) was measured by nitroblue tetrazolium and 2′7′-dichlorofluorescein diacetate assay. Matrix metalloproteinase activity was investigated by zymography and immunoblot assay. Phagocytotic activity was assessed by use of latex beads. KEY RESULTS Kaempferol significantly attenuated LPS-induced NO, PGE2, TNF-α, IL-1β and ROS production and phagocytosis in a concentration-dependent manner. Kaempferol suppressed the expression of iNOS, COX-2, MMP-3 and blocked the TLR4 activation. Moreover, kaempferol inhibited LPS-induced NF-κB activation and p38 MAPK, JNK and AKT phosphorylation. CONCLUSION AND IMPLICATIONS Kaempferol was able to reduce LPS-induced inflammatory mediators through the down-regulation of TLR4, NF-κB, p38 MAPK, JNK and AKT suggesting that kaempferol has therapeutic potential for the treatment of neuroinflammatory diseases. PMID:21449918

  6. Differential expression of miRNA-146a-regulated inflammatory genes in human primary neural, astroglial and microglial cells

    PubMed Central

    Li, Yuan Yuan; Cui, Jian Guo; Dua, Prerna; Pogue, Aileen I.; Bhattacharjee, Surjyadipta; Lukiw, Walter J.

    2013-01-01

    Micro RNA-146a (miRNA-146a) is an inducible, 22 nucleotide, small RNA over-expressed in Alzheimer’s disease (AD) brain. Up-regulated miRNA-146a targets several inflammation-related and membrane-associated messenger RNAs (mRNAs), including those encoding complement factor-H (CFH) and the interleukin-1 receptor associated kinase-1 (IRAK-1), resulting in significant decreases in their expression (p < 0.05, ANOVA). In this study we assayed miRNA-146a, CFH, IRAK-1 and tetraspanin-12 (TSPAN12), abundances in primary human neuronal-glial (HNG) co-cultures, in human astroglial (HAG) and microglial (HMG) cells stressed with Aβ42 peptide and tumor necrosis factor alpha (TNFα). The results indicate a consistent inverse relationship between miRNA-146a and CFH, IRAK-1 and TSPAN12 expression levels, and indicate that HNG, HAG and HMG cell types each respond differently to Aβ42-peptide + TNFα-triggered stress. While the strongest miRNA-146a-IRAK-1 response was found in HAG cells, the largest miRNA-146a-TSPAN12 response was found in HNG cells, and the most significant miRNA-146a-CFH changes were found in HMG cells, the ‘resident scavenging macrophages’ of the brain. PMID:21640790

  7. Estradiol attenuates spinal cord injury-induced pain by suppressing microglial activation in thalamic VPL nuclei of rats.

    PubMed

    Saghaei, Elham; Abbaszadeh, Fatemeh; Naseri, Kobra; Ghorbanpoor, Samar; Afhami, Mina; Haeri, Ali; Rahimi, Farzaneh; Jorjani, Masoumeh

    2013-04-01

    In our previous study we showed that central pain syndrome (CPS) induced by electrolytic injury caused in the unilateral spinothalamic tract (STT) is a concomitant of glial alteration at the site of injury. Here, we investigated the activity of glial cells in thalamic ventral posterolateral nuclei (VPL) and their contribution to CPS. We also examined whether post-injury administration of a pharmacological dose of estradiol can attenuate CPS and associated molecular changes. Based on the results,in the ipsilateral VPL the microglial phenotype switched o hyperactive mode and Iba1 expression was increased significantly on days 21 and 28 post-injury. The same feature was observed in contralateral VPL on day 28 (P<.05). These changes were strongly correlated with the onset of CPS (r(2)=0.670). STT injury did not induce significant astroglial response in both ipsilateral and contralateral VPL. Estradiol attenuated bilateral mechanical hypersensitivity 14 days after STT lesion (P<.05). Estradiol also suppressed microglial activation in the VPL. Taken together, these findings indicate that selective STT lesion induces bilateral microglia activation in VPL which might contribute to mechanical hypersensitivity. Furthermore, a pharmacological dose of estradiol reduces central pain possibly via suppression of glial activity in VPL region. PMID:23419864

  8. Cannabinoids and neuronal damage: differential effects of THC, AEA and 2-AG on activated microglial cells and degenerating neurons in excitotoxically lesioned rat organotypic hippocampal slice cultures.

    PubMed

    Kreutz, Susanne; Koch, Marco; Ghadban, Chalid; Korf, Horst-Werner; Dehghani, Faramarz

    2007-01-01

    Cannabinoids (CBs) are attributed neuroprotective effects in vivo. Here, we determined the neuroprotective potential of CBs during neuronal damage in excitotoxically lesioned organotypic hippocampal slice cultures (OHSCs). OHSCs are the best characterized in vitro model to investigate the function of microglial cells in neuronal damage since blood-borne monocytes and T-lymphocytes are absent and microglial cells represent the only immunocompetent cell type. Excitotoxic neuronal damage was induced by NMDA (50 microM) application for 4 h. Neuroprotective properties of 9-carboxy-11-nor-delta-9-tetrahydrocannabinol (THC), N-arachidonoylethanolamide (AEA) or 2-arachidonoylglycerol (2-AG) in different concentrations were determined after co-application with NMDA by counting degenerating neurons identified by propidium iodide labeling (PI(+)) and microglial cells labeled by isolectin B(4) (IB(4)(+)). All three CBs used significantly decreased the number of IB(4)(+) microglial cells in the dentate gyrus but the number of PI(+) neurons was reduced only after 2-AG treatment. Application of AM630, antagonizing CB2 receptors highly expressed by activated microglial cells, did not counteract neuroprotective effects of 2-AG, but affected THC-mediated reduction of IB(4)(+) microglial cells. Our results indicate that (1) only 2-AG exerts neuroprotective effects in OHSCs; (2) reduction of IB(4)(+) microglial cells is not a neuroprotective event per se and involves other CB receptors than the CB2 receptor; (3) the discrepancy in the neuroprotective effects of CBs observed in vivo and in our in vitro model system may underline the functional relevance of invading monocytes and T-lymphocytes that are absent in OHSCs. PMID:17010339

  9. Mechanisms Underlying Interferon-γ-Induced Priming of Microglial Reactive Oxygen Species Production.

    PubMed

    Spencer, Nicholas G; Schilling, Tom; Miralles, Francesc; Eder, Claudia

    2016-01-01

    Microglial priming and enhanced reactivity to secondary insults cause substantial neuronal damage and are hallmarks of brain aging, traumatic brain injury and neurodegenerative diseases. It is, thus, of particular interest to identify mechanisms involved in microglial priming. Here, we demonstrate that priming of microglia with interferon-γ (IFN γ) substantially enhanced production of reactive oxygen species (ROS) following stimulation of microglia with ATP. Priming of microglial ROS production was substantially reduced by inhibition of p38 MAPK activity with SB203580, by increases in intracellular glutathione levels with N-Acetyl-L-cysteine, by blockade of NADPH oxidase subunit NOX2 activity with gp91ds-tat or by inhibition of nitric oxide production with L-NAME. Together, our data indicate that priming of microglial ROS production involves reduction of intracellular glutathione levels, upregulation of NADPH oxidase subunit NOX2 and increases in nitric oxide production, and suggest that these simultaneously occurring processes result in enhanced production of neurotoxic peroxynitrite. Furthermore, IFNγ-induced priming of microglial ROS production was reduced upon blockade of Kir2.1 inward rectifier K+ channels with ML133. Inhibitory effects of ML133 on microglial priming were mediated via regulation of intracellular glutathione levels and nitric oxide production. These data suggest that microglial Kir2.1 channels may represent novel therapeutic targets to inhibit excessive ROS production by primed microglia in brain pathology. PMID:27598576

  10. Prenylated Flavonoids from Cudrania tricuspidata Suppress Lipopolysaccharide-Induced Neuroinflammatory Activities in BV2 Microglial Cells

    PubMed Central

    Kim, Dong-Cheol; Yoon, Chi-Su; Quang, Tran Hong; Ko, Wonmin; Kim, Jong-Su; Oh, Hyuncheol; Kim, Youn-Chul

    2016-01-01

    In Korea and China, Cudrania tricuspidata Bureau (Moraceae) is an important traditional medicinal plant used to treat lumbago, hemoptysis, and contusions. The C. tricuspidata methanol extract suppressed both production of NO and PGE2 in BV2 microglial cells. Cudraflavanone D (1), isolated from this extract, remarkably suppressed the protein expression of inducible NO synthase and cyclooxygenase-2, and decreased the levels of NO and PGE2 in BV2 microglial cells exposed to lipopolysaccharide. Cudraflavanone D (1) also decreased IL-6, TNF-α, IL-12, and IL-1β production, blocked nuclear translocation of NF-κB heterodimers (p50 and p65) by interrupting the degradation and phosphorylation of inhibitor of IκB-α, and inhibited NF-κB binding. In addition, cudraflavanone D (1) suppressed the phosphorylation of c-Jun N-terminal kinase (JNK) and p38 MAPK pathways. This study indicated that cudraflavanone D (1) can be a potential drug candidate for the cure of neuroinflammation. PMID:26907256

  11. Prenylated Flavonoids from Cudrania tricuspidata Suppress Lipopolysaccharide-Induced Neuroinflammatory Activities in BV2 Microglial Cells.

    PubMed

    Kim, Dong-Cheol; Yoon, Chi-Su; Quang, Tran Hong; Ko, Wonmin; Kim, Jong-Su; Oh, Hyuncheol; Kim, Youn-Chul

    2016-01-01

    In Korea and China, Cudrania tricuspidata Bureau (Moraceae) is an important traditional medicinal plant used to treat lumbago, hemoptysis, and contusions. The C. tricuspidata methanol extract suppressed both production of NO and PGE₂ in BV2 microglial cells. Cudraflavanone D (1), isolated from this extract, remarkably suppressed the protein expression of inducible NO synthase and cyclooxygenase-2, and decreased the levels of NO and PGE₂ in BV2 microglial cells exposed to lipopolysaccharide. Cudraflavanone D (1) also decreased IL-6, TNF-α, IL-12, and IL-1β production, blocked nuclear translocation of NF-κB heterodimers (p50 and p65) by interrupting the degradation and phosphorylation of inhibitor of IκB-α, and inhibited NF-κB binding. In addition, cudraflavanone D (1) suppressed the phosphorylation of c-Jun N-terminal kinase (JNK) and p38 MAPK pathways. This study indicated that cudraflavanone D (1) can be a potential drug candidate for the cure of neuroinflammation. PMID:26907256

  12. Microglial NLRP3 inflammasome activation mediates IL-1β-related inflammation in prefrontal cortex of depressive rats.

    PubMed

    Pan, Ying; Chen, Xu-Yang; Zhang, Qing-Yu; Kong, Ling-Dong

    2014-10-01

    Depression is an inflammatory disorder. Pro-inflammatory cytokine interleukin-1 beta (IL-1β) may play a pivotal role in the central nervous system (CNS) inflammation of depression. Here, we investigated IL-1β alteration in serum, cerebrospinal fluid (CSF) and prefrontal cortex (PFC) of chronic unpredictable mild stress (CUMS)-exposed rats, a well-documented model of depression, and further explored the molecular mechanism by which CUMS procedure induced IL-1β-related CNS inflammation. We showed that 12-week CUMS procedure remarkably increased PFC IL-1β mRNA and protein levels in depressive-like behavior of rats, without significant alteration of serum and CSF IL-1β levels. We found that CUMS procedure significantly caused PFC nuclear factor kappa B (NF-κB) inflammatory pathway activation in rats. The intriguing finding in this study was the induced activation of nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome with the increased IL-1β maturation in PFC of CUMS rats, suggesting a new grade of regulatory mechanism for IL-1β-related CNS inflammation. Moreover, microglial activation and astrocytic function impairment were observed in PFC of CUMS rats. The increased co-location of NLRP3 and ionized calcium binding adaptor molecule 1 (Iba1) protein expression supported that microglia in glial cells was the primary contributor for CUMS-induced PFC NLRP3 inflammasome activation in rats. These alterations in CUMS rats were restored by chronic treatment of the antidepressant fluoxetine, indicating that fluoxetine-mediated rat PFC IL-1β reduction involves both transcriptional and post-transcriptional regulatory mechanisms. These findings provide in vivo evidence that microglial NLRP3 inflammasome activation is a mediator of IL-1β-related CNS inflammation during chronic stress, and suggest a new therapeutic target for the prevention and treatment of depression. PMID:24859041

  13. Acute HCV/HIV Coinfection Is Associated with Cognitive Dysfunction and Cerebral Metabolite Disturbance, but Not Increased Microglial Cell Activation

    PubMed Central

    Garvey, Lucy J.; Pavese, Nicola; Ramlackhansingh, Anil; Thomson, Emma; Allsop, Joanna M.; Politis, Marios; Kulasegaram, Ranjababu; Main, Janice; Brooks, David J.; Taylor-Robinson, Simon D.; Winston, Alan

    2012-01-01

    Background Microglial cell activation and cerebral function impairment are described in both chronic hepatitis C viral (HCV) and Human-Immune-Deficiency viral (HIV) infections. The aim of this study was to investigate the effect of acute HCV infection upon cerebral function and microglial cell activation in HIV-infected individuals. Methods A case-control study was conducted. Subjects with acute HCV and chronic HIV coinfection (aHCV) were compared to matched controls with chronic HIV monoinfection (HIVmono). aHCV was defined as a new positive plasma HCV RNA within 12 months of a negative RNA test. Subjects underwent neuro-cognitive testing (NCT), cerebral proton magnetic resonance spectroscopy (1H-MRS) and positron emission tomography (PET) using a 11C-radiolabeled ligand (PK11195), which is highly specific for translocator protein 18 kDA receptors on activated microglial cells. Differences between cases and controls were assessed using linear regression modelling. Results Twenty-four aHCV cases completed NCT and 1H-MRS, 8 underwent PET. Of 57 HIVmono controls completing NCT, 12 underwent 1H-MRS and 8 PET. Subjects with aHCV demonstrated on NCT, significantly poorer executive function (mean (SD) error rate 26.50(17.87) versus 19.09(8.12), p = 0.001) and on 1H-MRS increased myo-inositol/creatine ratios (mI/Cr, a marker of cerebral inflammation) in the basal ganglia (ratio of 0.71(0.22) versus 0.55(0.23), p = 0.03), compared to subjects with HIVmono. On PET imaging, no difference in 11C-PK11195 binding potential (BP) was observed between study groups (p>0.10 all cerebral locations), however lower BPs were associated with combination antiretroviral therapy (cART) use in the parietal (p = 0.01) and frontal (p = 0.03) cerebral locations. Discussion Poorer cognitive performance and disturbance of cerebral metabolites are observed in subjects with aHC,V compared to subjects with HIVmono. Higher 11C-PK11195 BP was not observed in subjects with aHCV, but was

  14. Methylene blue exerts a neuroprotective effect against traumatic brain injury by promoting autophagy and inhibiting microglial activation

    PubMed Central

    ZHAO, MINGFEI; LIANG, FENG; XU, HANGDI; YAN, WEI; ZHANG, JIANMIN

    2016-01-01

    Traumatic brain injury (TBI) leads to permanent neurological impairment, and methylene blue (MB) exerts central nervous system neuroprotective effects. However, only one previous study has investigated the effectiveness of MB in a controlled cortical impact injury model of TBI. In addition, the specific mechanisms underlying the effect of MB against TBI remain to be elucidated. Therefore, the present study investigated the neuroprotective effect of MB on TBI and the possible mechanisms involved. In a mouse model of TBI, the animals were randomly divided into sham, vehicle (normal saline) or MB groups. The treatment time-points were 24 and 72 h (acute phase of TBI), and 14 days (chronic phase of TBI) post-TBI. The brain water content (BWC), and levels of neuronal death, and autophagy were determined during the acute phase, and neurological deficit, injury volume and microglial activation were assessed at all time-points. The injured hemisphere BWC was significantly increased 24 h post-TBI, and this was attenuated following treatment with MB. There was a significantly higher number of surviving neurons in the MB group, compared with the Vehicle group at 24 and 72 h post-TBI. In the acute phase, the MB-treated animals exhibited significantly upregulated expression of Beclin 1 and increased LC3-II to LC3-I ratios, compared with the vehicle group, indicating an increased rate of autophagy. Neurological functional deficits, measured using the modified neurological severity score, were significantly lower in the acute phase in the MB-treated animals and cerebral lesion volumes in the MB-treated animals were significantly lower, compared with the other groups at all time-points. Microglia were activated 24 h after TBI, peaked at 72 h and persisted until 14 days after TBI. Although the number of Iba-1-positive cells in the vehicle and MB groups 24 h post-TBI were not significantly different, marked microglial inhibition was observed in the MB group 72 h and 14 days after

  15. Early and protective microglial activation in Alzheimer's disease: a prospective study using 18F-DPA-714 PET imaging.

    PubMed

    Hamelin, Lorraine; Lagarde, Julien; Dorothée, Guillaume; Leroy, Claire; Labit, Mickael; Comley, Robert A; de Souza, Leonardo Cruz; Corne, Helene; Dauphinot, Luce; Bertoux, Maxime; Dubois, Bruno; Gervais, Philippe; Colliot, Olivier; Potier, Marie Claude; Bottlaender, Michel; Sarazin, Marie

    2016-04-01

    While emerging evidence suggests that neuroinflammation plays a crucial role in Alzheimer's disease, the impact of the microglia response in Alzheimer's disease remains a matter of debate. We aimed to study microglial activation in early Alzheimer's disease and its impact on clinical progression using a second-generation 18-kDa translocator protein positron emission tomography radiotracer together with amyloid imaging using Pittsburgh compound B positron emission tomography. We enrolled 96 subjects, 64 patients with Alzheimer's disease and 32 controls, from the IMABio3 study, who had both(11)C-Pittsburgh compound B and(18)F-DPA-714 positron emission tomography imaging. Patients with Alzheimer's disease were classified as prodromal Alzheimer's disease (n= 38) and Alzheimer's disease dementia (n= 26). Translocator protein-binding was measured using a simple ratio method with cerebellar grey matter as reference tissue, taking into account regional atrophy. Images were analysed at the regional (volume of interest) and at the voxel level. Translocator protein genotyping allowed the classification of all subjects in high, mixed and low affinity binders. Thirty high+mixed affinity binders patients with Alzheimer's disease were dichotomized into slow decliners (n=10) or fast decliners (n=20) after 2 years of follow-up. All patients with Alzheimer's disease had an amyloid positive Pittsburgh compound B positron emission tomography. Among controls, eight had positive amyloid scans (n= 6 high+mixed affinity binders), defined as amyloidosis controls, and were analysed separately. By both volumes of interest and voxel-wise comparison, 18-kDa translocator protein-binding was higher in high affinity binders, mixed affinity binders and high+mixed affinity binders Alzheimer's disease groups compared to controls, especially at the prodromal stage, involving the temporo-parietal cortex. Translocator protein-binding was positively correlated with Mini-Mental State Examination scores

  16. P17.40GLIOMA ASSOCIATED MICROGLIAL MMP9 EXPRESSION IS UP REGULATED BY TLR2 SIGNALLING AND SENSITIVE TO MINOCYCLINE

    PubMed Central

    Hu, F.; Ku, M.; Markovic, D.; Dzaye, O. Dildar a; Lehnardt, S.; Wolf, S.A.; Kettenmann, H.; Synowitz, M.

    2014-01-01

    OBJECTIVE: The invasiveness of malignant gliomas is one of the major obstacles in glioma therapy and the reason for the poor survival of patients. Glioma cells infiltrate into the brain parenchyma and thereby escape surgical resection. Glioma—associated microglia/macrophages (GAMs) support glioma infiltration into the brain parenchyma by increased expression and activation of extracellular matrix degrading proteases such as maxtrix—metalloprotease (MMP)—2, MMP—9 and MT1—MMP. METHODS: Using in vitro, ex vivo, and in vivo techniques, we identified TLR2 as the main TLR controlling microglial MMP9 expression and promoting microglia assisted glioma expansion. RESULTS: In this work we demonstrate that MMP—9 is predominantly expressed by GAMs in mouse and human glioma tissue but not by the glioma cells. Supernatant from glioma cells induced the expression of MMP—9 in cultured microglial cells. Using mice deficient for different toll—like receptors (TLRs) we identified TLR2/6 as the signalling pathway for the glioma induced upregulation of microglial MMP—9. Also in an experimental mouse glioma model, TLR2 deficiency attenuated the upregulation of microglial MMP—9. Moreover, glioma supernatant triggered an upregulation of TLR2 expression in microglia. Both, the upregulation of MMP—9 and TLR2 were attenuated by the antibiotic minocycline and a p38 MAPK antagonist in vitro. Minocycline also extended the survival rate of glioma bearing mice when given to the drinking water. CONCLUSIONS: Thus glioma cells change the phenotype of GAMs in a complex fashion using TLR2 as an important signalling pathway and minocycline further proved to be a potential candidate for adjuvant glioma therapy.

  17. Microglial Cells as a Link between Cannabinoids and the Immune Hypothesis of Psychiatric Disorders.

    PubMed

    Lisboa, Sabrina F; Gomes, Felipe V; Guimaraes, Francisco S; Campos, Alline C

    2016-01-01

    Psychiatric disorders are one of the leading causes of disability worldwide. Although several therapeutic options are available, the exact mechanisms responsible for the genesis of these disorders remain to be fully elucidated. In the last decade, a body of evidence has supported the involvement of the immune system in the pathophysiology of these conditions. Microglial cells play a significant role in maintaining brain homeostasis and surveillance. Dysregulation of microglial functions has been associated with several psychiatric conditions. Cannabinoids regulate the brain-immune axis and inhibit microglial cell activation. Here, we summarized evidence supporting the hypothesis that microglial cells could be a target for cannabinoid influence on psychiatric disorders, such as anxiety, depression, schizophrenia, and stress-related disorders. PMID:26858686

  18. Microglial Cells as a Link between Cannabinoids and the Immune Hypothesis of Psychiatric Disorders

    PubMed Central

    Lisboa, Sabrina F.; Gomes, Felipe V.; Guimaraes, Francisco S.; Campos, Alline C.

    2016-01-01

    Psychiatric disorders are one of the leading causes of disability worldwide. Although several therapeutic options are available, the exact mechanisms responsible for the genesis of these disorders remain to be fully elucidated. In the last decade, a body of evidence has supported the involvement of the immune system in the pathophysiology of these conditions. Microglial cells play a significant role in maintaining brain homeostasis and surveillance. Dysregulation of microglial functions has been associated with several psychiatric conditions. Cannabinoids regulate the brain–immune axis and inhibit microglial cell activation. Here, we summarized evidence supporting the hypothesis that microglial cells could be a target for cannabinoid influence on psychiatric disorders, such as anxiety, depression, schizophrenia, and stress-related disorders. PMID:26858686

  19. Fasudil inhibits LPS-induced migration of retinal microglial cells via regulating p38-MAPK signaling pathway

    PubMed Central

    Xu, Fan; Xu, Yue; Zhu, Liqiong; Rao, Pinhong; Wen, Jiamin; Sang, Yunyun; Shang, Fu

    2016-01-01

    Purpose To investigate the effect and possible molecular mechanisms of fasudil on retinal microglial (RMG) cell migration. Methods Primary cultured RMG cells were incubated with lipopolysaccharide (LPS), fasudil, and/or SB203580 (a p38 inhibitor). RMG cell motility was determined with the scratch wound assay and the Transwell migration assay. The phosphorylation of p38 and levels of matrix metalloproteinase 2 (MMP-2) and MMP-9 were measured with western blot. Results In the scratch-induced migration assay, as well as in the Transwell migration assay, the results indicated that LPS stimulated the migratory potential of RMG cells and fasudil significantly reduced LPS-stimulated RMG cell migration in a concentration-dependent manner. However, fasudil had no effect on RMG cell migration in the absence of LPS stimulation. Moreover, fasudil reduced the level of phosphor-p38 mitogen-activated protein kinase (p-p38-MAPK) in a concentration-dependent manner, without effects on the levels of phospho-p44/42 (p-ERK1/2) and phospho-c-Jun N-terminal kinase (p-JNK). Cotreatment with SB203580 (a p38 inhibitor) and fasudil resulted in the synergistic reduction of MMP-2, MMP-9, and p-p38-MAPK, as well as a reduction in the LPS-stimulated migration capabilities of the RMG cells, suggesting fasudil suppresses the LPS-stimulated migration of RMG cells via directly downregulating the p38-MAPK signaling pathway. Conclusions Our studies indicated that fasudil inhibited LPS-stimulated RMG cell migration via suppression of the p38-MAPK signaling pathway. PMID:27441000

  20. Alterations in blood-brain barrier ICAM-1 expression and brain microglial activation after λ-carrageenan-induced inflammatory pain

    PubMed Central

    Huber, J. D.; Campos, C. R.; Mark, K. S.; Davis, T. P.

    2014-01-01

    Previous studies showed that peripheral inflammatory pain increased blood-brain barrier (BBB) permeability and altered tight junction protein expression and the delivery of opioid analgesics to the brain. What remains unknown is which pathways and mediators during peripheral inflammation affect BBB function and structure. The current study investigated effects of λ-carrageenan-induced inflammatory pain (CIP) on BBB expression of ICAM-1. We also examined the systemic contribution of a number of proinflammatory cytokines and microglial activation in the brain to elucidate pathways involved in BBB disruption during CIP. We investigated ICAM-1 RNA and protein expression levels in isolated rat brain microvessels after CIP using RT-PCR and Western blot analyses, screened inflammatory cytokines during the time course of inflammation, assessed white blood cell counts, and probed for BBB and central nervous system stimulation and leukocyte transmigration using immunohistochemistry and flow cytometry. Results showed an early increase in ICAM-1 RNA and protein expression after CIP with no change in circulating levels of several proinflammatory cytokines. Changes in ICAM-1 protein expression were noted at 48 h. Immunohistochemistry showed that the induction of ICAM-1 was region specific with increased expression noted in the thalamus and frontal and parietal cortices, which directly correlated with increased expression of activated microglia. The findings of the present study were that CIP induces increased ICAM-1 mRNA and protein expression at the BBB and that systemic proinflammatory mediators play no apparent role in the early response (1–6 h); however, brain region-specific increases in micro-glial activation suggest a potential for a central-mediated response. PMID:16199477

  1. Rho-Associated Kinase Inhibitors Promote Microglial Uptake Via the ERK Signaling Pathway.

    PubMed

    Fu, Peicai; Tang, Ronghua; Yu, Zhiyuan; Li, Caihong; Chen, Xue; Xie, Minjie; Wang, Wei; Luo, Xiang

    2016-02-01

    Microglia are immunocompetent cells in the central nervous system that take up tissue debris and pathogens. Rho-associated kinase (ROCK) has been identified as an important regulator of uptake, proliferation, secretion, and differentiation in a number of cell types. Although ROCK plays critical roles in the microglial secretion of inflammatory factors, migration, and morphology, its effects on microglial uptake activity have not been well characterized. In the present study, we found that treatment of BV2 microglia and primary microglia with the ROCK inhibitors Y27632 and fasudil increased uptake activity and was associated with morphological changes. Furthermore, western blots showed that this increase in uptake activity was mediated through the extracellular-signal-regulated kinase (ERK) signaling cascade, indicating the importance of ROCK in regulating microglial uptake activity. PMID:26779919

  2. Microglial activity in people at ultra high risk of psychosis and in schizophrenia; an [11C]PBR28 PET brain imaging study

    PubMed Central

    Veronese, Mattia; Rizzo, Gaia; Bertoldo, Alessandra; Owen, David R; Bloomfield, Michael AP; Bonoldi, Ilaria; Kalk, Nicola; Turkheimer, Federico; McGuire, Philip

    2016-01-01

    Objective To determine whether microglial activity, measured using translocator-protein positron emission tomographic imaging (PET), is increased in unmedicated subjects presenting with sub-clinical symptoms indicating they are at ultra high risk of psychosis, and to determine if it is elevated in schizophrenia after controlling for a translocator specific genetic polymorphism. Method Here we use the second generation radioligand [11C]PBR28 and PET to image microglial activity in the brains of subjects at ultra high risk for psychosis. Subjects were recruited from early intervention centres. We also imaged a cohort of patients with schizophrenia and healthy controls for comparison, in total 56 subjects completed the study. At screening, subjects were genotyped to account for the rs6971 polymorphism in the gene encoding the 18Kd Translocator Protein. The main outcome measure was total grey matter [11C]PBR28 binding ratio, representing microglial activity. Results [11C]PBR28 binding ratio in grey matter was elevated in ultra high risk subjects, compared to matched controls, (p=0.004, F= 10.3, Cohen’s d >1.2), and was positively correlated with symptom severity (r= 0.730, p<0.01). Patients with schizophrenia also demonstrated elevated microglial activity with respect to matched controls (p<0.001, F= 20.8, Cohen’s d >1.7). Conclusion Microglial activity is elevated in schizophrenia and in subjects with sub-clinical symptoms who are at ultra high risk of psychosis, and is related to at risk symptom severity. This indicates that neuroinflammation is linked to the risk of psychosis and related disorders, and the expression of sub-clinical symptoms. Follow up of ultra high risk subjects will determine whether this is specific to the later development of schizophrenia or risk factors in general. PMID:26472628

  3. Neuronal and microglial regulators of cortical wiring: usual and novel guideposts

    PubMed Central

    Squarzoni, Paola; Thion, Morgane S.; Garel, Sonia

    2015-01-01

    Neocortex functioning relies on the formation of complex networks that begin to be assembled during embryogenesis by highly stereotyped processes of cell migration and axonal navigation. The guidance of cells and axons is driven by extracellular cues, released along by final targets or intermediate targets located along specific pathways. In particular, guidepost cells, originally described in the grasshopper, are considered discrete, specialized cell populations located at crucial decision points along axonal trajectories that regulate tract formation. These cells are usually early-born, transient and act at short-range or via cell-cell contact. The vast majority of guidepost cells initially identified were glial cells, which play a role in the formation of important axonal tracts in the forebrain, such as the corpus callosum, anterior, and post-optic commissures as well as optic chiasm. In the last decades, tangential migrating neurons have also been found to participate in the guidance of principal axonal tracts in the forebrain. This is the case for several examples such as guideposts for the lateral olfactory tract (LOT), corridor cells, which open an internal path for thalamo-cortical axons and Cajal-Retzius cells that have been involved in the formation of the entorhino-hippocampal connections. More recently, microglia, the resident macrophages of the brain, were specifically observed at the crossroads of important neuronal migratory routes and axonal tract pathways during forebrain development. We furthermore found that microglia participate to the shaping of prenatal forebrain circuits, thereby opening novel perspectives on forebrain development and wiring. Here we will review the last findings on already known guidepost cell populations and will discuss the role of microglia as a potentially new class of atypical guidepost cells. PMID:26236185

  4. Safflower Yellow regulates microglial polarization and inhibits inflammatory response in LPS-stimulated Bv2 cells.

    PubMed

    Yang, Xing-Wang; Li, Yan-Hua; Zhang, Hui; Zhao, Yong-Fei; Ding, Zhi-Bin; Yu, Jie-Zhong; Liu, Chun-Yun; Liu, Jian-Chun; Jiang, Wei-Jia; Feng, Qian-Jin; Xiao, Bao-Guo; Ma, Cun-Gen

    2016-03-01

    Activated microglia, especially polarized M1 cells, produce pro-inflammatory cytokines and free radicals, thereby contributing directly to neuroinflammation and various brain disorders. Given that excessive or chronic neuroinflammation within the central nervous system (CNS) exacerbates neuronal damage, molecules that modulate neuroinflammation are candidates as neuroprotective agents. In this study, we provide evidence that Safflor yellow (SY), the main active component in the traditional Chinese medicine safflower, modulates inflammatory responses by acting directly on BV2 microglia. LPS stimulated BV2 cells to upregulate expression of TLR4-Myd88 and MAPK-NF-κB signaling pathways and to release IL-1β, IL-6, TNF-α, and COX-2. However, SY treatment inhibited expression of TLR4-Myd88 and p-38/p-JNK-NF-κB, downregulated expression of iNOS, CD16/32, and IL-12, and upregulated CD206 and IL-10. In conclusion, our results demonstrate that SY exerts an anti-inflammatory effect on BV2 microglia, possibly through TLR-4/p-38/p-JNK/NF-κB signaling pathways and the conversion of microglia from inflammatory M1 to an anti-inflammatory M2 phenotype. PMID:26634402

  5. Remote Astrocytic and Microglial Activation Modulate Neuronal Hyperexcitability and Below-Level Neuropathic Pain after Spinal Injury in Rat

    PubMed Central

    Gwak, Young Seob; Hulsebosch, Claire E.

    2010-01-01

    In this study, we evaluated whether astrocytic and microglial activation mediates below-level neuropathic pain following spinal cord injury. Male Sprague-Dawley (225–250 g) rats were given low thoracic (T13) spinal transverse hemisection and behavioral, electrophysiological and immunohistochemical methods were used to examine the development and maintenance of below-level neuropathic pain. On post operation day 28, both hindlimbs showed significantly decreased paw withdrawal thresholds and thermal latencies as well as hyperexcitability of lumbar (L4-5) spinal wide dynamic range (WDR) neurons on both sides of spinal dorsal horn compared to sham controls (*p<0.05). Intrathecal treatment with propentofylline (PPF, 10 mM) for 7 consecutive days immediately after spinal injury attenuated the development of mechanical allodynia and thermal hyperalgesia in both hindlimbs in a dose related reduction compared to vehicle treatments (*p<0.05). Intrathecal treatment with single injections of PPF at 28 days after spinal injury, attenuated the existing mechanical allodynia and thermal hyperalgesia in both hindlimbs in a dose related reduction (*p<0.05). In electrophysiological studies, topical treatment of 10 mM PPF onto the spinal surface attenuated the neuronal hyperexcitability in response to mechanical stimuli. In immunohistochemical studies, astrocytes and microglia in rats with spinal hemisection showed significantly increased GFAP and OX-42 expression in both superficial and deep dorsal horns in the lumbar spinal dorsal horn compared to sham controls (*p<0.05) that was prevented in a dose related manner by PPF. In conclusion, our present data support astrocytic and microglial activation that contributes to below-level central neuropathic pain following spinal cord injury. PMID:19332108

  6. Depression as a microglial disease.

    PubMed

    Yirmiya, Raz; Rimmerman, Neta; Reshef, Ronen

    2015-10-01

    Despite decades of intensive research, the biological mechanisms that causally underlie depression are still unclear, and therefore the development of novel effective antidepressant treatments is hindered. Recent studies indicate that impairment of the normal structure and function of microglia, caused by either intense inflammatory activation (e.g., following infections, trauma, stroke, short-term stress, autoimmune or neurodegenerative diseases) or by decline and senescence of these cells (e.g., during aging, Alzheimer's disease, or chronic unpredictable stress exposure), can lead to depression and associated impairments in neuroplasticity and neurogenesis. Accordingly, some forms of depression can be considered as a microglial disease (microgliopathy), which should be treated by a personalized medical approach using microglial inhibitors or stimulators depending on the microglial status of the depressed patient. PMID:26442697

  7. In vivo imaging of microglial activation by positron emission tomography with [(11)C]PBR28 in the 5XFAD model of Alzheimer's disease.

    PubMed

    Mirzaei, Nazanin; Tang, Sac Pham; Ashworth, Sharon; Coello, Christopher; Plisson, Christophe; Passchier, Jan; Selvaraj, Vimal; Tyacke, Robin J; Nutt, David J; Sastre, Magdalena

    2016-06-01

    Microglial activation has been linked with deficits in neuronal function and synaptic plasticity in Alzheimer's disease (AD). The mitochondrial translocator protein (TSPO) is known to be upregulated in reactive microglia. Accurate visualization and quantification of microglial density by PET imaging using the TSPO tracer [(11)C]-R-PK11195 has been challenging due to the limitations of the ligand. In this study, it was aimed to evaluate the new TSPO tracer [(11)C]PBR28 as a marker for microglial activation in the 5XFAD transgenic mouse model of AD. Dynamic PET scans were acquired following intravenous administration of [(11)C]PBR28 in 6-month-old 5XFAD mice and in wild-type controls. Autoradiography with [(3)H]PBR28 was carried out in the same brains to further confirm the distribution of the radioligand. In addition, immunohistochemistry was performed on adjacent brain sections of the same mice to evaluate the co-localization of TSPO with microglia. PET imaging revealed that brain uptake of [(11)C]PBR28 in 5XFAD mice was increased compared with control mice. Moreover, binding of [(3)H]PBR28, measured by autoradiography, was enriched in cortical and hippocampal brain regions, coinciding with the positive staining of the microglial marker Iba-1 and amyloid deposits in the same areas. Furthermore, double-staining using antibodies against TSPO demonstrated co-localization of TSPO with microglia and not with astrocytes in 5XFAD mice and human post-mortem AD brains. The data provided support of the suitability of [(11)C]PBR28 as a tool for in vivo monitoring of microglial activation and assessment of treatment response in future studies using animal models of AD. PMID:26959396

  8. Coordinated role of voltage-gated sodium channels and the Na{sup +}/H{sup +} exchanger in sustaining microglial activation during inflammation

    SciTech Connect

    Hossain, Muhammad M.; Sonsalla, Patricia K.; Richardson, Jason R.

    2013-12-01

    Persistent neuroinflammation and microglial activation play an integral role in the pathogenesis of many neurological disorders. We investigated the role of voltage-gated sodium channels (VGSC) and Na{sup +}/H{sup +} exchangers (NHE) in the activation of immortalized microglial cells (BV-2) after lipopolysaccharide (LPS) exposure. LPS (10 and 100 ng/ml) caused a dose- and time-dependent accumulation of intracellular sodium [(Na{sup +}){sub i}] in BV-2 cells. Pre-treatment of cells with the VGSC antagonist tetrodotoxin (TTX, 1 μM) abolished short-term Na{sup +} influx, but was unable to prevent the accumulation of (Na{sup +}){sub i} observed at 6 and 24 h after LPS exposure. The NHE inhibitor cariporide (1 μM) significantly reduced accumulation of (Na{sup +}){sub i} 6 and 24 h after LPS exposure. Furthermore, LPS increased the mRNA expression and protein level of NHE-1 in a dose- and time-dependent manner, which was significantly reduced after co-treatment with TTX and/or cariporide. LPS increased production of TNF-α, ROS, and H{sub 2}O{sub 2} and expression of gp91{sup phox}, an active subunit of NADPH oxidase, in a dose- and time-dependent manner, which was significantly reduced by TTX or TTX + cariporide. Collectively, these data demonstrate a closely-linked temporal relationship between VGSC and NHE-1 in regulating function in activated microglia, which may provide avenues for therapeutic interventions aimed at reducing neuroinflammation. - Highlights: • LPS causes immediate increase in sodium through VGSC and subsequently through the NHE-1. • Inhibition of VGSC reduces increases in NHE-1 and gp91{sup phox}. • Inhibition of VGSC and NHE-1 reduces NADPH oxidase-mediated Tnf-α, ROS, and H{sub 2}O{sub 2} production. • NHE-1 and Na{sub v}1.6 may be viable targets for therapeutic interventions to reduce neuroinflammation in neurodegenerative disease.

  9. Downregulation of NO and PGE2 in LPS-stimulated BV2 microglial cells by trans-isoferulic acid via suppression of PI3K/Akt-dependent NF-κB and activation of Nrf2-mediated HO-1.

    PubMed

    Dilshara, Matharage Gayani; Lee, Kyoung-Tae; Jayasooriya, Rajapaksha Gedara Prasad Tharanga; Kang, Chang-Hee; Park, Sang Rul; Choi, Yung Hyun; Choi, Il-Whan; Hyun, Jin-Won; Chang, Weon-Young; Kim, Yeon-Su; Lee, Hak-Ju; Kim, Gi-Young

    2014-01-01

    Little is known about whether trans-isoferulic acid (TIA) regulates the production of lipopolysaccharide (LPS)-induced proinflammatory mediators. Therefore, we examined the effect of TIA isolated from Clematis mandshurica on LPS-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production in BV2 microglial cells. We found that TIA inhibited the production of LPS-induced NO and PGE2 without accompanying cytotoxicity in BV2 microglial cells. TIA also downregulated the expression levels of specific regulatory genes such as inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) by suppressing LPS-induced NF-κB activity via dephosphorylation of PI3K/Akt. In addition, we demonstrated that a specific NF-κB inhibitor PDTC and a selective PI3K/Akt inhibitor, LY294002 effectively attenuated the expression of LPS-stimulated iNOS and COX-2 mRNA, while LY294002 suppressed LPS-induced NF-κB activity, suggesting that TIA attenuates the expression of these proinflammatory genes by suppressing PI3K/Akt-mediated NF-κB activity. Our results showed that TIA suppressed NO and PGE2 production through the induction of nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent heme oxygenase-1 (HO-1). Taken together, our data indicate that TIA suppresses the production of proinflammatory mediators such as NO and PGE2, as well as their regulatory genes, in LPS-stimulated BV2 microglial cells, by inhibiting PI3K/Akt-dependent NF-κB activity and enhancing Nrf2-mediated HO-1 expression. PMID:24291391

  10. Glial Cell Line-Derived Neurotrophic Factor Family Members Reduce Microglial Activation via Inhibiting p38MAPKs-Mediated Inflammatory Responses

    PubMed Central

    Rickert, Uta; Grampp, Steffen; Wilms, Henrik; Spreu, Jessica; Knerlich-Lukoschus, Friederike; Held-Feindt, Janka; Lucius, Ralph

    2014-01-01

    Previous studies have shown that glial cell line-derived neurotrophic factor (GDNF) family ligands (GFL) are potent survival factors for dopaminergic neurons and motoneurons with therapeutic potential for Parkinson's disease. However, little is known about direct influences of the GFL on microglia function, which are known to express part of the GDNF receptor system. Using RT-PCR and immunohistochemistrym we investigated the expression of the GDNF family receptor alpha 1 (GFR alpha) and the coreceptor transmembrane receptor tyrosine kinase (RET) in rat microglia in vitro as well as the effect of GFL on the expression of proinflammatory molecules in LPS activated microglia. We could show that GFL are able to regulate microglia functions and suggest that part of the well known neuroprotective action may be related to the suppression of microglial activation. We further elucidated the functional significance and pathophysiological implications of these findings and demonstrate that microglia are target cells of members of the GFL (GDNF and the structurally related neurotrophic factors neurturin (NRTN), artemin (ARTN), and persephin (PSPN)). PMID:26317008

  11. Inhibitory effect of ent-Sauchinone on amyloidogenesis via inhibition of STAT3-mediated NF-κB activation in cultured astrocytes and microglial BV-2 cells

    PubMed Central

    2014-01-01

    Background ent-Sauchinone is a polyphenolic compound found in plants belonging to the lignan family. ent-Sauchinone has been shown to modulate the expression of inflammatory factors through the nuclear factor-kappa B (NF-κB) signaling pathway. It is well known that neuroinflammation is associated with amyloidogenesis. Thus, in the present study, we investigated whether ent-Sauchinone could have anti-amyloidogenic effects through the inhibition of NF-κB pathways via its anti-inflammatory property. Methods To investigate the potential effect of ent-Sauchinone on anti-neuroinflammation and anti-amyloidogenesis in in vitro studies, we used microglial BV-2 cells and cultured astrocytes treated with ent-Sauchinone (1, 5, and 10 μM) for 24 hours. For the detection of anti-neuro-inflammatory responses, reative oxygen species (ROS) and Nitric oxide (NO) generation and inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression were measured with assay kits and western blotting. β-secretase and β-secretase activities and β-amyloid levels were determined for measuring the anti-amyloidogenic effects of ent-Sauchinone by enzyme assay kits. NF-κB and STAT3 signals were detected with electromobility shift assay (EMSA) to study the related signaling pathways. The binding of ent-Sauchinone to STAT3 was evaluated by a pull-down assay and by a docking model using Autodock VINA software (Hoover’s Inc., Texas, United states). Results ent-Sauchinone (1, 5, and 10 μM) effectively decreased lipopolysaccharide (LPS)-(1 μg/ml) induced inflammatory responses through the reduction of ROS and NO generations and iNOS and COX-2 expressions in cultured astrocytes and microglial BV-2 cells. ent-Sauchinone also inhibited LPS-induced amyloidogenesis through the inhibition of β-secretase and β-secretase activity. NF- κB amyloid and STAT3, critical transcriptional factors regulating not only inflammation but also amyloidogenesis, were also inhibited in a

  12. Frataxin Deficiency Promotes Excess Microglial DNA Damage and Inflammation that Is Rescued by PJ34

    PubMed Central

    Shen, Yan; McMackin, Marissa Z.; Shan, Yuxi; Raetz, Alan; David, Sheila; Cortopassi, Gino

    2016-01-01

    An inherited deficiency in the frataxin protein causes neurodegeneration of the dorsal root ganglia and Friedreich's ataxia (FA). Frataxin deficiency leads to oxidative stress and inflammatory changes in cell and animal models; however, the cause of the inflammatory changes, and especially what causes brain microglial activation is unclear. Here we investigated: 1) the mechanism by which frataxin deficiency activates microglia, 2) whether a brain-localized inflammatory stimulus provokes a greater microglial response in FA animal models, and 3) whether an anti-inflammatory treatment improves their condition. Intracerebroventricular administration of LPS induced higher amounts of microglial activation in the FA mouse model vs controls. We also observed an increase in oxidative damage in the form of 8-oxoguanine (8-oxo-G) and the DNA repair proteins MUTYH and PARP-1 in cerebellar microglia of FA mutant mice. We hypothesized that frataxin deficiency increases DNA damage and DNA repair genes specifically in microglia, activating them. siRNA-mediated frataxin knockdown in microglial BV2 cells clearly elevated DNA damage and the expression of DNA repair genes MUTYH and PARP-1. Frataxin knockdown also induced a higher level of PARP-1 in MEF cells, and this was suppressed in MUTYH-/- knockout cells. Administration of the PARP-1 inhibitor PJ34 attenuated the microglial activation induced by intracerebroventricular injection of LPS. The combined administration of LPS and angiotensin II provoke an even stronger activation of microglia and neurobehavioral impairment. PJ34 treatment attenuated the neurobehavioral impairments in FA mice. These results suggest that the DNA repair proteins MUTYH and PARP-1 may form a pathway regulating microglial activation initiated by DNA damage, and inhibition of microglial PARP-1 induction could be an important therapeutic target in Friedreich's ataxia. PMID:26954031

  13. Frataxin Deficiency Promotes Excess Microglial DNA Damage and Inflammation that Is Rescued by PJ34.

    PubMed

    Shen, Yan; McMackin, Marissa Z; Shan, Yuxi; Raetz, Alan; David, Sheila; Cortopassi, Gino

    2016-01-01

    An inherited deficiency in the frataxin protein causes neurodegeneration of the dorsal root ganglia and Friedreich's ataxia (FA). Frataxin deficiency leads to oxidative stress and inflammatory changes in cell and animal models; however, the cause of the inflammatory changes, and especially what causes brain microglial activation is unclear. Here we investigated: 1) the mechanism by which frataxin deficiency activates microglia, 2) whether a brain-localized inflammatory stimulus provokes a greater microglial response in FA animal models, and 3) whether an anti-inflammatory treatment improves their condition. Intracerebroventricular administration of LPS induced higher amounts of microglial activation in the FA mouse model vs controls. We also observed an increase in oxidative damage in the form of 8-oxoguanine (8-oxo-G) and the DNA repair proteins MUTYH and PARP-1 in cerebellar microglia of FA mutant mice. We hypothesized that frataxin deficiency increases DNA damage and DNA repair genes specifically in microglia, activating them. siRNA-mediated frataxin knockdown in microglial BV2 cells clearly elevated DNA damage and the expression of DNA repair genes MUTYH and PARP-1. Frataxin knockdown also induced a higher level of PARP-1 in MEF cells, and this was suppressed in MUTYH-/- knockout cells. Administration of the PARP-1 inhibitor PJ34 attenuated the microglial activation induced by intracerebroventricular injection of LPS. The combined administration of LPS and angiotensin II provoke an even stronger activation of microglia and neurobehavioral impairment. PJ34 treatment attenuated the neurobehavioral impairments in FA mice. These results suggest that the DNA repair proteins MUTYH and PARP-1 may form a pathway regulating microglial activation initiated by DNA damage, and inhibition of microglial PARP-1 induction could be an important therapeutic target in Friedreich's ataxia. PMID:26954031

  14. Withania somnifera and Its Withanolides Attenuate Oxidative and Inflammatory Responses and Up-Regulate Antioxidant Responses in BV-2 Microglial Cells.

    PubMed

    Sun, Grace Y; Li, Runting; Cui, Jiankun; Hannink, Mark; Gu, Zezong; Fritsche, Kevin L; Lubahn, Dennis B; Simonyi, Agnes

    2016-09-01

    Withania somnifera (L.) Dunal, commonly known as Ashwagandha, has been used in Ayurvedic medicine for promoting health and quality of life. Recent clinical trials together with experimental studies indicated significant neuroprotective effects of Ashwagandha and its constituents. This study is aimed to investigate anti-inflammatory and anti-oxidative properties of this botanical and its two withanolide constituents, namely, Withaferin A and Withanolide A, using the murine immortalized BV-2 microglial cells. Ashwagandha extracts not only effectively inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO) and reactive oxygen species (ROS) production in BV-2 cells, but also stimulates the Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway, leading to induction of heme oxygenase-1 (HO-1), both in the presence and absence of LPS. Although the withanolides were also capable of inhibiting LPS-induced NO production and stimulating Nrf2/HO-1 pathway, Withaferin A was tenfold more effective than Withanolide A. In serum-free culture, LPS can also induce production of long thin processes (filopodia) between 4 and 8 h in BV-2 cells. This morphological change was significantly suppressed by Ashwagandha and both withanolides at concentrations for suppressing LPS-induced NO production. Taken together, these results suggest an immunomodulatory role for Ashwagandha and its withanolides, and their ability to suppress oxidative and inflammatory responses in microglial cells by simultaneously down-regulating the NF-kB and upregulating the Nrf2 pathways. PMID:27209361

  15. Ethanol downregulates N-acyl phosphatidylethanolamine-phospholipase D expression in BV2 microglial cells via epigenetic mechanisms.

    PubMed

    Correa, Fernando; De Laurentiis, Andrea; Franchi, Ana María

    2016-09-01

    Excessive ethanol drinking has deleterious effects on the brain. However, the effects of alcohol on microglia, the main mediator of the brain's innate immune response remain poorly understood. On the other hand, the endocannabinoid system plays a fundamental role in regulating microglial reactivity and function. Here we studied the effects of acute ethanol exposure to murine BV2 microglial cells on N-acyl phosphatidylethanolamine-phospholipase D (NAPE-PLD), a major synthesizing enzyme of anandamide and other N-acylethanolamines. We found that ethanol downregulated microglial NAPE-PLD expression by activating cAMP/PKA and ERK1/2. These signaling pathways converged on increased phosphorylation of CREB. Moreover, ethanol induced and increase in histone acetyltransferase activity which led to higher levels of acetylation of histone H3. Taken together, our results suggest that ethanol actions on microglial NAPE-PLD expression might involve epigenetic mechanisms. PMID:27266665

  16. Autologous bone marrow mononuclear cells therapy attenuates activated microglial/macrophage response and improves spatial learning after traumatic brain injury

    PubMed Central

    Bedi, Supinder S.; Walker, Peter A.; Shah, Shinil K.; Jimenez, Fernando; Thomas, Chelsea P.; Smith, Philippa; Hetz, Robert A.; Xue, Hasen; Pati, Shibani; Dash, Pramod K.; Cox, Charles S.

    2014-01-01

    Background Autologous bone marrow-derived mononuclear cells (AMNC) have shown therapeutic promise for central nervous system insults such as stroke and traumatic brain injury (TBI). We hypothesized that intravenous injection of AMNC provides neuroprotection which leads to cognitive improvement after TBI. Methods A controlled cortical impact (CCI) rodent traumatic brain injury (TBI) model was used to examine blood-brain barrier permeability (BBB), neuronal and glial apoptosis and cognitive behavior. Two groups of rats underwent CCI with (CCI-Autologous) or without AMNC treatment (CCI-Alone), consisting of 2 million AMNC/kilogram body weight harvested from the tibia and intravenously injected 72 hr after injury. CCI-Alone animals underwent sham harvests and received vehicle injections. Results 96 hr after injury, AMNC significantly reduced the BBB permeability in injured animals, and there was an increase in apoptosis of pro-inflammatory activated microglia in the ipsilateral hippocampus. At 4 weeks after injury, we examined changes in spatial memory after TBI due to AMNC treatment. There was a significant improvement in probe testing of CCI-Autologous group in comparison to CCI-Alone in the Morris Water Maze paradigm. Conclusions Our data demonstrate that the intravenous injection of AMNC after TBI leads to neuroprotection by preserving early BBB integrity and increasing activated microglial apoptosis. In addition, AMNC also improves cognitive function. PMID:23928737

  17. Microglial AGE-albumin is critical in promoting alcohol-induced neurodegeneration in rats and humans.

    PubMed

    Byun, Kyunghee; Bayarsaikhan, Delger; Bayarsaikhan, Enkhjargal; Son, Myeongjoo; Oh, Seyeon; Lee, Jaesuk; Son, Hye-In; Won, Moo-Ho; Kim, Seung U; Song, Byoung-Joon; Lee, Bonghee

    2014-01-01

    Alcohol is a neurotoxic agent, since long-term heavy ingestion of alcohol can cause various neural diseases including fetal alcohol syndrome, cerebellar degeneracy and alcoholic dementia. However, the molecular mechanisms of alcohol-induced neurotoxicity are still poorly understood despite numerous studies. Thus, we hypothesized that activated microglial cells with elevated AGE-albumin levels play an important role in promoting alcohol-induced neurodegeneration. Our results revealed that microglial activation and neuronal damage were found in the hippocampus and entorhinal cortex following alcohol treatment in a rat model. Increased AGE-albumin synthesis and secretion were also observed in activated microglial cells after alcohol exposure. The expressed levels of receptor for AGE (RAGE)-positive neurons and RAGE-dependent neuronal death were markedly elevated by AGE-albumin through the mitogen activated protein kinase pathway. Treatment with soluble RAGE or AGE inhibitors significantly diminished neuronal damage in the animal model. Furthermore, the levels of activated microglial cells, AGE-albumin and neuronal loss were significantly elevated in human brains from alcoholic indivisuals compared to normal controls. Taken together, our data suggest that increased AGE-albumin from activated microglial cells induces neuronal death, and that efficient regulation of its synthesis and secretion is a therapeutic target for preventing alcohol-induced neurodegeneration. PMID:25140518

  18. Deferoxamine inhibits microglial activation, attenuates blood-brain barrier disruption, rescues dendritic damage, and improves spatial memory in a mouse model of microhemorrhages.

    PubMed

    He, Xiao-Fei; Lan, Yue; Zhang, Qun; Liu, Dong-Xu; Wang, Qinmei; Liang, Feng-Ying; Zeng, Jin-Sheng; Xu, Guang-Qing; Pei, Zhong

    2016-08-01

    Cerebral microbleeds are strongly linked to cognitive dysfunction in the elderly. Iron accumulation plays an important role in the pathogenesis of intracranial hemorrhage. Deferoxamine (DFX), a metal chelator, removes iron overload and protects against brain damage in intracranial hemorrhage. In this study, the protective effects of DFX against microhemorrhage were examined in mice. C57BL6 and Thy-1 green fluorescent protein transgenic mice were subjected to perforating artery microhemorrhages on the right posterior parietal cortex using two-photon laser irradiation. DFX (100 mg/kg) was administered 6 h after microhemorrhage induction, followed by every 12 h for three consecutive days. The water maze task was conducted 7 days after induction of microhemorrhages, followed by measurement of blood-brain barrier permeability, iron deposition, microglial activation, and dendritic damage. Laser-induced multiple microbleeds in the right parietal cortex clearly led to spatial memory disruption, iron deposits, microglial activation, and dendritic damage, which were significantly attenuated by DFX, supporting the targeting of iron overload as a therapeutic option and the significant potential of DFX in microhemorrhage treatment. Irons accumulation after intracranial hemorrhage induced a serious secondary damage to the brain. We proposed that irons accumulation after parietal microhemorrhages impaired spatial cognition. After parietal multiple microhemorrhages, increased irons and ferritin contents induced blood-brain barrier disruption, microglial activation, and further induced dendrites loss, eventually impaired the water maze, deferoxamine treatment protected from these damages. PMID:27167158

  19. Inhibition of Peripheral TNF-α and Downregulation of Microglial Activation by Alpha-Lipoic Acid and Etanercept Protect Rat Brain Against Ischemic Stroke.

    PubMed

    Wu, Ming-Hsiu; Huang, Chao-Ching; Chio, Chung-Ching; Tsai, Kuen-Jer; Chang, Ching-Ping; Lin, Nan-Kai; Lin, Mao-Tsun

    2016-09-01

    Ischemic stroke, caused by obstruction of blood flow to the brain, would initiate microglia activation which contributes to neuronal damage. Therefore, inhibition of microglia-mediated neuroinflammation could be a therapeutic strategy for ischemic stroke. This study was aimed to elucidate the anti-inflammatory effects of alpha-lipoic acid and etanercept given either singly or in combination in rats subjected to middle cerebral artery occlusion. Both α-lipoic acid and etanercept markedly reduced cerebral infarct, blood-brain barrier disruption, and neurological motor deficits with the former drug being more effective with the dosage used. Furthermore, when used in combination, the reduction was more substantial. Remarkably, a greater diminution in the serum levels of tumor necrosis factor-alpha as well as the brain levels of microglial activation (e.g., microgliosis, amoeboid microglia, and microglial overexpression of tumor necrosis factor-α) was observed with the combined drug treatment as compared to the drugs given separately. We conclude that inhibition of peripheral tumor necrosis factor-alpha as well as downregulation of brain microglial activation by alpha-lipoic acid or etanercept protect rat brain against ischemic stroke. Moreover, when both drugs were used in combination, the stroke recovery was promoted more extensively. PMID:26374550

  20. Fractalkine receptor deficiency impairs microglial and neuronal responsiveness to chronic stress.

    PubMed

    Milior, Giampaolo; Lecours, Cynthia; Samson, Louis; Bisht, Kanchan; Poggini, Silvia; Pagani, Francesca; Deflorio, Cristina; Lauro, Clotilde; Alboni, Silvia; Limatola, Cristina; Branchi, Igor; Tremblay, Marie-Eve; Maggi, Laura

    2016-07-01

    Chronic stress is one of the most relevant triggering factors for major depression. Microglial cells are highly sensitive to stress and, more generally, to environmental challenges. However, the role of these brain immune cells in mediating the effects of stress is still unclear. Fractalkine signaling - which comprises the chemokine CX3CL1, mainly expressed by neurons, and its receptor CX3CR1, almost exclusively present on microglia in the healthy brain - has been reported to critically regulate microglial activity. Here, we investigated whether interfering with microglial function by deleting the Cx3cr1 gene affects the brain's response to chronic stress. To this purpose, we housed Cx3cr1 knockout and wild-type adult mice in either control or stressful environments for 2weeks, and investigated the consequences on microglial phenotype and interactions with synapses, synaptic transmission, behavioral response and corticosterone levels. Our results show that hampering neuron-microglia communication via the CX3CR1-CX3CL1 pathway prevents the effects of chronic unpredictable stress on microglial function, short- and long-term neuronal plasticity and depressive-like behavior. Overall, the present findings suggest that microglia-regulated mechanisms may underlie the differential susceptibility to stress and consequently the vulnerability to diseases triggered by the experience of stressful events, such as major depression. PMID:26231972

  1. Intravenous Multipotent Adult Progenitor Cell Therapy Attenuates Activated Microglial/Macrophage Response and Improves Spatial Learning After Traumatic Brain Injury

    PubMed Central

    Bedi, Supinder S.; Hetz, Robert; Thomas, Chelsea; Smith, Philippa; Olsen, Alex B.; Williams, Stephen; Xue, Hasen; Aroom, Kevin; Uray, Karen; Hamilton, Jason; Mays, Robert W.

    2013-01-01

    We previously demonstrated that the intravenous delivery of multipotent adult progenitor cells (MAPCs) after traumatic brain injury (TBI) in rodents provides neuroprotection by preserving the blood-brain barrier and systemically attenuating inflammation in the acute time frame following cell treatment; however, the long-term behavioral and anti-inflammatory effects of MAPC administration after TBI have yet to be explored. We hypothesized that the intravenous injection of MAPCs after TBI attenuates the inflammatory response (as measured by microglial morphology) and improves performance at motor tasks and spatial learning (Morris water maze [MWM]). MAPCs were administered intravenously 2 and 24 hours after a cortical contusion injury (CCI). We tested four groups at 120 days after TBI: sham (uninjured), injured but not treated (CCI), and injured and treated with one of two concentrations of MAPCs, either 2 million cells per kilogram (CCI-2) or 10 million cells per kilogram (CCI-10). CCI-10 rats showed significant improvement in left hind limb deficit on the balance beam. On the fifth day of MWM trials, CCI-10 animals showed a significant decrease in both latency to platform and distance traveled compared with CCI. Probe trials revealed a significant decrease in proximity measure in CCI-10 compared with CCI, suggesting improved memory retrieval. Neuroinflammation was quantified by enumerating activated microglia in the ipsilateral hippocampus. We observed a significant decrease in the number of activated microglia in the dentate gyrus in CCI-10 compared with CCI. Our results demonstrate that intravenous MAPC treatment after TBI in a rodent model offers long-term improvements in spatial learning as well as attenuation of neuroinflammation. PMID:24191266

  2. Reticulocalbin-1 Facilitates Microglial Phagocytosis

    PubMed Central

    Ding, Ying; Caberoy, Nora B.; Guo, Feiye; LeBlanc, Michelle E.; Zhang, Chenming; Wang, Weiwen; Wang, Feng; Chen, Rui; Li, Wei

    2015-01-01

    Phagocytosis is critical to the clearance of apoptotic cells, cellular debris and deleterious metabolic products for tissue homeostasis. Phagocytosis ligands directly recognizing deleterious cargos are the key to defining the functional roles of phagocytes, but are traditionally identified on a case-by-case basis with technical challenges. As a result, extrinsic regulation of phagocytosis is poorly defined. Here we demonstrate that microglial phagocytosis ligands can be systematically identified by a new approach of functional screening. One of the identified ligands is reticulocalbin-1 (Rcn1), which was originally reported as a Ca2+-binding protein with a strict expression in the endoplasmic reticulum. Our results showed that Rcn1 can be secreted from healthy cells and that secreted Rcn1 selectively bound to the surface of apoptotic neurons, but not healthy neurons. Independent characterization revealed that Rcn1 stimulated microglial phagocytosis of apoptotic but not healthy neurons. Ingested apoptotic cells were targeted to phagosomes and co-localized with phagosome marker Rab7. These data suggest that Rcn1 is a genuine phagocytosis ligand. The new approach described in this study will enable systematic identification of microglial phagocytosis ligands with broad applicability to many other phagocytes. PMID:25992960

  3. Cytomegalovirus Infection of the Rat Developing Brain In Utero Prominently Targets Immune Cells and Promotes Early Microglial Activation

    PubMed Central

    Cloarec, Robin; Bauer, Sylvian; Luche, Hervé; Buhler, Emmanuelle; Pallesi-Pocachard, Emilie; Salmi, Manal; Courtens, Sandra; Massacrier, Annick; Grenot, Pierre; Teissier, Natacha; Watrin, Françoise; Schaller, Fabienne; Adle-Biassette, Homa; Gressens, Pierre; Malissen, Marie; Stamminger, Thomas; Streblow, Daniel N.; Bruneau, Nadine; Szepetowski, Pierre

    2016-01-01

    Background Congenital cytomegalovirus infections are a leading cause of neurodevelopmental disorders in human and represent a major health care and socio-economical burden. In contrast with this medical importance, the pathophysiological events remain poorly known. Murine models of brain cytomegalovirus infection, mostly neonatal, have brought recent insights into the possible pathogenesis, with convergent evidence for the alteration and possible involvement of brain immune cells. Objectives and Methods In order to confirm and expand those findings, particularly concerning the early developmental stages following infection of the fetal brain, we have created a model of in utero cytomegalovirus infection in the developing rat brain. Rat cytomegalovirus was injected intraventricularly at embryonic day 15 (E15) and the brains analyzed at various stages until the first postnatal day, using a combination of gene expression analysis, immunohistochemistry and multicolor flow cytometry experiments. Results Rat cytomegalovirus infection was increasingly seen in various brain areas including the choroid plexi and the ventricular and subventricular areas and was prominently detected in CD45low/int, CD11b+ microglial cells, in CD45high, CD11b+ cells of the myeloid lineage including macrophages, and in CD45+, CD11b– lymphocytes and non-B non-T cells. In parallel, rat cytomegalovirus infection of the developing rat brain rapidly triggered a cascade of pathophysiological events comprising: chemokines upregulation, including CCL2-4, 7 and 12; infiltration by peripheral cells including B-cells and monocytes at E17 and P1, and T-cells at P1; and microglia activation at E17 and P1. Conclusion In line with previous findings in neonatal murine models and in human specimen, our study further suggests that neuroimmune alterations might play critical roles in the early stages following cytomegalovirus infection of the brain in utero. Further studies are now needed to determine which

  4. Mycobacterium tuberculosis upregulates microglial matrix metalloproteinase-1 and -3 expression and secretion via NF-kappaB- and Activator Protein-1-dependent monocyte networks.

    PubMed

    Green, Justin A; Elkington, Paul T; Pennington, Caroline J; Roncaroli, Federico; Dholakia, Shruti; Moores, Rachel C; Bullen, Anwen; Porter, Joanna C; Agranoff, Dan; Edwards, Dylan R; Friedland, Jon S

    2010-06-01

    Inflammatory tissue destruction is central to pathology in CNS tuberculosis (TB). We hypothesized that microglial-derived matrix metalloproteinases (MMPs) have a key role in driving such damage. Analysis of all of the MMPs demonstrated that conditioned medium from Mycobacterium tuberculosis-infected human monocytes (CoMTb) stimulated greater MMP-1, -3, and -9 gene expression in human microglial cells than direct infection. In patients with CNS TB, MMP-1/-3 immunoreactivity was demonstrated in the center of brain granulomas. Concurrently, CoMTb decreased expression of the inhibitors, tissue inhibitor of metalloproteinase-2, -3, and -4. MMP-1/-3 secretion was significantly inhibited by dexamethasone, which reduces mortality in CNS TB. Surface-enhanced laser desorption ionization time-of-flight analysis of CoMTb showed that TNF-alpha and IL-1beta are necessary but not sufficient for upregulating MMP-1 secretion and act synergistically to drive MMP-3 secretion. Chemical inhibition and promoter-reporter analyses showed that NF-kappaB and AP-1 c-Jun/FosB heterodimers regulate CoMTb-induced MMP-1/-3 secretion. Furthermore, NF-kappaB p65 and AP-1 c-Jun subunits were upregulated in biopsy granulomas from patients with cerebral TB. In summary, functionally unopposed, network-dependent microglial MMP-1/-3 gene expression and secretion regulated by NF-kappaB and AP-1 subunits were demonstrated in vitro and, for the first time, in CNS TB patients. Dexamethasone suppression of MMP-1/-3 gene expression provides a novel mechanism explaining the benefit of steroid therapy in these patients. PMID:20483790

  5. Attenuation of microglial activation with minocycline is not associated with changes in neurogenesis after focal traumatic brain injury in adult mice.

    PubMed

    Ng, Si Yun; Semple, Bridgette D; Morganti-Kossmann, M Cristina; Bye, Nicole

    2012-05-01

    Neurogenesis is stimulated following injury to the adult brain and could potentially contribute to tissue repair. However, evidence suggests that microglia activated in response to injury are detrimental to the survival of new neurons, thus limiting the neurogenic response. The aim of this study was to determine the effect of the anti-inflammatory drug minocycline on neurogenesis and functional recovery after a closed head injury model of focal traumatic brain injury (TBI). Beginning 30 min after trauma, minocycline was administered for up to 2 weeks and bromodeoxyuridine was given on days 1-4 to label proliferating cells. Neurological outcome and motor function were evaluated over 6 weeks using the Neurological Severity Score (NSS) and ledged beam task. Microglial activation was assessed in the pericontusional cortex and hippocampus at 1 week post-trauma, using immunohistochemistry to detect F4/80. Following immunolabeling of bromodeoxyuridine, double-cortin, and NeuN, cells undergoing distinct stages of neurogenesis, including proliferation, neuronal differentiation, neuroblast migration, and long-term survival, were quantified at 1 and 6 weeks in the hippocampal dentate gyrus, as well as in the subventricular zone of the lateral ventricles and the pericontusional cortex. Our results show that minocycline successfully reduced microglial activation and promoted early neurological recovery that was sustained over 6 weeks. We also show for the first time in the closed head injury model, that early stages of neurogenesis were stimulated in the hippocampus and subventricular zone; however, no increase in new mature neurons occurred. Contrary to our hypothesis, despite the attenuation of activated microglia, minocycline did not support neurogenesis in the hippocampus, lateral ventricles, or pericontusional cortex, with none of the neurogenic stages being affected by treatment. These data provide evidence that a general suppression of microglial activation is

  6. Electroacupuncture pretreatment prevents cognitive impairment induced by limb ischemia-reperfusion via inhibition of microglial activation and attenuation of oxidative stress in rats.

    PubMed

    Chen, Ye; Zhou, Jun; Li, Jun; Yang, Shi-Bin; Mo, Li-Qun; Hu, Jie-Hui; Yuan, Wan-Li

    2012-01-13

    Limb ischemia-reperfusion (LI/R) is associated with high morbidity and mortality. Furthermore, critical trauma survivors can present cognitive impairment. Cognitive function, survival rate, oxidative stress and neuronal health were examined to elucidate (1) the magnitude of cognitive effects of prolonged reperfusion, (2) potential players in the mechanistic pathway mediating such effects, and (3) possible benefits of electroacupuncture (EA) pretreatment at Baihui (GV20), Yanglingquan (GB34), Taichong (LR3), Zusanli (ST36) and Xuehai (SP10) acupoints. LI/R was induced in rats by placing a rubber tourniquet on each hind limb for 3h, and the animals were evaluated periodically for 7d after LI/R. Rats subjected to LI/R had significantly lower survival rates, and displayed evidence of brain injury and cognitive dysfunction (as determined by the Morris water maze test) 1d and 3d after reperfusion compared to sham-operated controls. LI/R also resulted in higher levels of reactive oxygen species (ROS) and malondialdehyde (MDA), microglial activation, and decreased superoxide dismutase (SOD) activity within Cornu Ammonis area 1 (CA1) of the hippocampus. Depressed survival rates, microglial activation, oxidative damage, and histological changes, as well as cognitive dysfunction were partially or fully attenuated in rats that received 14d of EA prior to LI/R. These findings indicate that LI/R can result in cognitive dysfunction related to activated microglia and elevated oxidative stress, and that EA has neuroprotective potential mediated, at least in part, by inhibition of microglial activation and attenuation of oxidative stress. PMID:22129788

  7. Preventive Effects of a Fermented Dairy Product against Alzheimer’s Disease and Identification of a Novel Oleamide with Enhanced Microglial Phagocytosis and Anti-Inflammatory Activity

    PubMed Central

    Ano, Yasuhisa; Ozawa, Makiko; Kutsukake, Toshiko; Sugiyama, Shinya; Uchida, Kazuyuki; Yoshida, Aruto; Nakayama, Hiroyuki

    2015-01-01

    Despite the ever-increasing number of patients with dementia worldwide, fundamental therapeutic approaches to this condition have not been established. Epidemiological studies suggest that intake of fermented dairy products prevents cognitive decline in the elderly. However, the active compounds responsible for the effect remain to be elucidated. The present study aims to elucidate the preventive effects of dairy products on Alzheimer’s disease and to identify the responsible component. Here, in a mouse model of Alzheimer’s disease (5xFAD), intake of a dairy product fermented with Penicillium candidum had preventive effects on the disease by reducing the accumulation of amyloid β (Aβ) and hippocampal inflammation (TNF-α and MIP-1α production), and enhancing hippocampal neurotrophic factors (BDNF and GDNF). A search for preventive substances in the fermented dairy product identified oleamide as a novel dual-active component that enhanced microglial Aβ phagocytosis and anti-inflammatory activity towards LPS stimulation in vitro and in vivo. During the fermentation, oleamide was synthesized from oleic acid, which is an abundant component of general dairy products owing to lipase enzymatic amidation. The present study has demonstrated the preventive effect of dairy products on Alzheimer’s disease, which was previously reported only epidemiologically. Moreover, oleamide has been identified as an active component of dairy products that is considered to reduce Aβ accumulation via enhanced microglial phagocytosis, and to suppress microglial inflammation after Aβ deposition. Because fermented dairy products such as camembert cheese are easy to ingest safely as a daily meal, their consumption might represent a preventive strategy for dementia. PMID:25760987

  8. Preventive effects of a fermented dairy product against Alzheimer's disease and identification of a novel oleamide with enhanced microglial phagocytosis and anti-inflammatory activity.

    PubMed

    Ano, Yasuhisa; Ozawa, Makiko; Kutsukake, Toshiko; Sugiyama, Shinya; Uchida, Kazuyuki; Yoshida, Aruto; Nakayama, Hiroyuki

    2015-01-01

    Despite the ever-increasing number of patients with dementia worldwide, fundamental therapeutic approaches to this condition have not been established. Epidemiological studies suggest that intake of fermented dairy products prevents cognitive decline in the elderly. However, the active compounds responsible for the effect remain to be elucidated. The present study aims to elucidate the preventive effects of dairy products on Alzheimer's disease and to identify the responsible component. Here, in a mouse model of Alzheimer's disease (5xFAD), intake of a dairy product fermented with Penicillium candidum had preventive effects on the disease by reducing the accumulation of amyloid β (Aβ) and hippocampal inflammation (TNF-α and MIP-1α production), and enhancing hippocampal neurotrophic factors (BDNF and GDNF). A search for preventive substances in the fermented dairy product identified oleamide as a novel dual-active component that enhanced microglial Aβ phagocytosis and anti-inflammatory activity towards LPS stimulation in vitro and in vivo. During the fermentation, oleamide was synthesized from oleic acid, which is an abundant component of general dairy products owing to lipase enzymatic amidation. The present study has demonstrated the preventive effect of dairy products on Alzheimer's disease, which was previously reported only epidemiologically. Moreover, oleamide has been identified as an active component of dairy products that is considered to reduce Aβ accumulation via enhanced microglial phagocytosis, and to suppress microglial inflammation after Aβ deposition. Because fermented dairy products such as camembert cheese are easy to ingest safely as a daily meal, their consumption might represent a preventive strategy for dementia. PMID:25760987

  9. Hydrangenol inhibits lipopolysaccharide-induced nitric oxide production in BV2 microglial cells by suppressing the NF-κB pathway and activating the Nrf2-mediated HO-1 pathway.

    PubMed

    Kim, Hee-Ju; Kang, Chang-Hee; Jayasooriya, Rajapaksha Gedara Prasad Tharanga; Dilshara, Matharage Gayani; Lee, Seungheon; Choi, Yung Hyun; Seo, Yong Taek; Kim, Gi-Young

    2016-06-01

    We previously demonstrated the anti-inflammatory effect of water extract of Hydrangea macrophylla in lipopolysaccharide (LPS)-stimulated macrophage cells. Here, we investigated whether hydrangenol, a bioactive component of H. macrophylla, attenuates the expression of nitric oxide (NO) and its associated gene, inducible NO synthase (iNOS), in LPS-stimulated BV2 microglial cells. Our data showed that low dosages of hydrangenol inhibited LPS-stimulated NO release and iNOS expression without any accompanying cytotoxicity. Hydrangenol also suppressed LPS-induced nuclear translocation of nuclear factor-κB (NF-κB) subunits, consequently inhibiting DNA-binding activity of NF-κB. Additionally, the NF-κB inhibitors, pyrrolidine dithiocarbamate (PDTC) and PS-1145, significantly attenuated LPS-induced iNOS expression, indicating that hydrangenol-induced NF-κB inhibition might be a key regulator of iNOS expression. Furthermore, our data showed that hydrangenol suppresses NO production by inducing heme oxygenase-1 (HO-1). The presence of cobalt protoporphyrin, a specific HO-1 inducer, potently suppressed LPS-induced NO production. Hydrangenol also promoted nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and subsequently increased its binding activity at the specific antioxidant response element sites. Additionally, transient knockdown of Nrf2 significantly downregulated hydrangenol-induced HO-1 expression, indicating that hydrangenol-induced Nrf2 is an upstream regulator of HO-1. Taken together, these data suggest that hydrangenol attenuates NO production and iNOS expression in LPS-stimulated BV2 microglial cells by inhibiting NF-κB activation and by stimulating the Nrf2-mediated HO-1 signaling pathway. Therefore, hydrangenol is a promising therapeutic agent for treatment of LPS-mediated inflammatory diseases. PMID:27032067

  10. Suppression of microglial activation is neuroprotective in a mouse model of human retinitis pigmentosa.

    PubMed

    Peng, Bo; Xiao, Jia; Wang, Ke; So, Kwok-Fai; Tipoe, George L; Lin, Bin

    2014-06-11

    Retinitis pigmentosa (RP) is a photoreceptor-degenerative disease caused by various mutations and is characterized by death of rod photoreceptor cell followed by gradual death of cone photoreceptors. The molecular mechanisms that lead to rod and cone death are not yet fully understood. Neuroinflammation contributes to the progression of many chronic neurodegenerative disorders. However, it remains to be determined how microglia contribute to photoreceptor disruption in RP. In this study, we explored the role of microglia as a contributor to photoreceptor degeneration in the rd10 mouse model of RP. First, we demonstrated that microglia activation was an early alteration in RP retinas. Inhibition of microglia activation by minocycline reduced photoreceptor apoptosis and significantly improved retinal structure and function and visual behavior in rd10 mice. Second, we identified that minocycline exerted its neuroprotective effects through both anti-inflammatory and anti-apoptotic mechanisms. Third, we found that Cx3cr1 deficiency dysregulated microglia activation and subsequently resulted in increased photoreceptor vulnerability in rd10 mice, suggesting that the Cx3cl1/Cx3cr1 signaling pathway might protect against microglia neurotoxicity. We concluded that suppression of neuroinflammatory responses could be a potential treatment strategy aimed at improving photoreceptor survival in human RP. PMID:24920619

  11. Peripheral and Central Effects of Repeated Social Defeat Stress: Monocyte Trafficking, Microglial Activation, and Anxiety

    PubMed Central

    Reader, Brenda F.; Jarrett, Brant L.; McKim, Daniel B.; Wohleb, Eric S.; Godbout, Jonathan P.; Sheridan, John F.

    2015-01-01

    The development and exacerbation of depression and anxiety are associated with exposure to repeated psychosocial stress. Stress is known to affect the bidirectional communication between the nervous and immune systems leading to elevated levels of stress mediators including glucocorticoids (GCs) and catecholamines and increased trafficking of proinflammatory immune cells. Animal models, like the repeated social defeat (RSD) paradigm, were developed to explore this connection between stress and affective disorders. RSD induces activation of the sympathetic nervous system (SNS) and hypothalamic-pituitary (HPA) axis activation, increases bone marrow production and egress of primed, GC-insensitive monocytes, and stimulates the trafficking of these cells to tissues including the spleen, lung, and brain. Recently, the observation that these monocytes have the ability to traffic to the brain perivascular spaces and parenchyma have provided mechanisms by which these peripheral cells may contribute to the prolonged anxiety-like behavior associated with RSD. The data that have been amassed from the RSD paradigm and others recapitulate many of the behavioral and immunological phenotypes associated with human anxiety disorders and may serve to elucidate potential avenues of treatment for these disorders. Here, we will discuss novel and key data that will present an overview of the neuroendocrine, immunological and behavioral responses to social stressors. PMID:25596319

  12. Maternal separation activates microglial cells and induces an inflammatory response in the hippocampus of male rat pups, independently of hypothalamic and peripheral cytokine levels.

    PubMed

    Roque, Angélica; Ochoa-Zarzosa, Alejandra; Torner, Luz

    2016-07-01

    Adult animals subjected to chronic stress show an inflammatory response in the hippocampus which has been related to cognitive dysfunction and psychopathology. However the immediate consequences of early life stress on hippocampal glial cells have not been studied. Here we analyzed the effects of maternal separation (MS) on astrocyte and microglial cell morphology in the hippocampal hilus, compared the expression of cytokines in the hippocampus and hypothalamus, and the peripheral response of cytokines, on postnatal day (PD) 15. Male rat pups of MS (3h/day, PD1-PD14) and Control (CONT) pups showed similar microglial cell densities in the hilus, but MS pups presented more activated microglia. MS decreased astrocyte density and the number of processes in the hilus. Cytokine mRNA expression (qPCR) was analyzed in MS and CONT groups, sacrificed (i) under basal (B) conditions or (ii) after a single stress event (SS) at PN15. In hippocampal extracts, MS increased IL-1β mRNA, under B and SS conditions while IL-6 and TNF-α did not change. In hypothalamic tissue, MS increased TNF-α and IL-6 mRNA, but not IL-1b, after SS. Peripheral concentrations of IL-1β were decreased under B and SS conditions in MS; IL-6 concentration increased after SS in MS pups, and TNF-α concentration was unchanged. In conclusion, MS activates microglial cells and decreases astrocyte density in the hippocampus. A differential cytokine expression is observed in the hippocampus and the hypothalamus after MS, and after SS. Also, MS triggers an independent response of peripheral cytokines. These specific responses together could contribute to decrease hippocampal neurogenesis and alter the neuroendocrine axis. PMID:26431692

  13. Involvement of mitogen-activated protein kinase and NF-κB signaling pathways in perfluorooctane sulfonic acid-induced inflammatory reaction in BV2 microglial cells.

    PubMed

    Zhu, Jingying; Qian, Wenyi; Wang, Yixin; Gao, Rong; Wang, Jun; Xiao, Hang

    2015-12-01

    Microglial activation is closely related to the pathogenesis of neurodegenerative diseases by producing proinflammatory cytokines. Perfluorooctane sulfonic acid (PFOS), known as an emerging persistent organic pollutant, is reported to disturb human immune homeostasis; however, whether it affects cytokine production or the immune response in the central nervous system remains unclear. The present study was aimed to explore whether PFOS contributed to inflammatory action and to investigate the corresponding mechanisms in BV2 microglia. PFOS-mediated morphologic changes, cytokine responses and signaling events were examined by light microscopy, real-time polymerase chain reaction, enzyme-linked immunosorbent assay and Western blot assays. Our results indicated that PFOS increased BV2 cells activation and simultaneously increased tumor necrosis factor alpha and interleukin-6 expression. In addition, the c-Jun N-terminal protein kinase inhibitor (SP600125), as well as ERK1/2 blocker (PD98059), transcriptionally at least, displayed anti-inflammatory properties on PFOS-elicited cytokine responses. Moreover, the inflammatory transcription factor NF-κB was specifically activated by PFOS as well. These results, taken together, suggested that PFOS exerts its functional effects on the response of microglial cell activation via, in part, the c-Jun N-terminal protein kinase, ERK and NF-κB signaling pathways with its subsequent influence on proinflammatory action. PMID:25677194

  14. beta2 Adrenergic receptor activation induces microglial NADPH oxidase activation and dopaminergic neurotoxicity through an ERK-dependent/protein kinase A-independent pathway.

    PubMed

    Qian, Li; Hu, Xiaoming; Zhang, Dan; Snyder, Amanda; Wu, Hung-Ming; Li, Yachen; Wilson, Belinda; Lu, Ru-Band; Hong, Jau-Shyong; Flood, Patrick M

    2009-11-15

    Activation of the beta2 adrenergic receptor (beta2AR) on immune cells has been reported to possess anti-inflammatory properties, however, the pro-inflammatory properties of beta2AR activation remain unclear. In this study, using rat primary mesencephalic neuron-glia cultures, we report that salmeterol, a long-acting beta2AR agonist, selectively induces dopaminergic (DA) neurotoxicity through its ability to activate microglia. Salmeterol selectively increased the production of reactive oxygen species (ROS) by NADPH oxidase (PHOX), the major superoxide-producing enzyme in microglia. A key role of PHOX in mediating salmeterol-induced neurotoxicity was demonstrated by the inhibition of DA neurotoxicity in cultures pretreated with diphenylene-iodonium (DPI), an inhibitor of PHOX activity. Mechanistic studies revealed the activation of microglia by salmeterol results in the selective phosphorylation of ERK, a signaling pathway required for the translocation of the PHOX cytosolic subunit p47(phox) to the cell membrane. Furthermore, we found ERK inhibition, but not protein kinase A (PKA) inhibition, significantly abolished salmeterol-induced superoxide production, p47(phox) translocation, and its ability to mediate neurotoxicity. Together, these findings indicate that beta2AR activation induces microglial PHOX activation and DA neurotoxicity through an ERK-dependent/PKA-independent pathway. PMID:19330844

  15. Microglial activation decreases retention of the protease inhibitor saquinavir: implications for HIV treatment

    PubMed Central

    2013-01-01

    Background Active HIV infection within the central nervous system (CNS) is confined primarily to microglia. The glial cell compartment acts as a viral reservoir behind the blood-brain barrier. It provides an additional roadblock to effective pharmacological treatment via expression of multiple drug efflux transporters, including P-glycoprotein. HIV/AIDS patients frequently suffer bacterial and viral co-infections, leading to deregulation of glial cell function and release of pro-inflammatory mediators including cytokines, chemokines, and nitric oxide. Methods To better define the role of inflammation in decreased HIV drug accumulation into CNS targets, accumulation of the antiretroviral saquinavir was examined in purified cultures of rodent microglia exposed to the prototypical inflammatory mediator lipopolysaccharide (LPS). Results [3H]-Saquinavir accumulation by microglia was rapid, and was increased up to two-fold in the presence of the specific P-glycoprotein inhibitor, PSC833. After six or 24 hours of exposure to 10 ng/ml LPS, saquinavir accumulation was decreased by up to 45%. LPS did not directly inhibit saquinavir transport, and did not affect P-glycoprotein protein expression. LPS exposure did not alter RNA and/or protein expression of other transporters including multidrug resistance-associated protein 1 and several solute carrier uptake transporters. Conclusions The decrease in saquinavir accumulation in microglia following treatment with LPS is likely multi-factorial, since drug accumulation was attenuated by inhibitors of NF-κβ and the MEK1/2 pathway in the microglia cell line HAPI, and in primary microglia cultures from toll-like receptor 4 deficient mice. These data provide new pharmacological insights into why microglia act as a difficult-to-treat viral sanctuary site. PMID:23642074

  16. Post-ischemic hypothermia reduced IL-18 expression and suppressed microglial activation in the immature brain.

    PubMed

    Fukui, On; Kinugasa, Yukiko; Fukuda, Aya; Fukuda, Hirotsugu; Tskitishvili, Ekaterine; Hayashi, Shusaku; Song, Mihyon; Kanagawa, Takeshi; Hosono, Takayoshi; Shimoya, Koichiro; Murata, Yuji

    2006-11-22

    the normothermia group, and there were no significant differences in the number of AM and RM between the hypothermia group and controls. In conclusion, we found that IL-18 mRNA and the protein level were attenuated by post-HI hypothermia and that post-HI hypothermia may decrease microglia activation in the developing brain. PMID:17010950

  17. Pharmacological targeting of CSF1R inhibits microglial proliferation and prevents the progression of Alzheimer’s-like pathology

    PubMed Central

    Olmos-Alonso, Adrian; Schetters, Sjoerd T. T.; Sri, Sarmi; Askew, Katharine; Mancuso, Renzo; Vargas-Caballero, Mariana; Holscher, Christian; Perry, V. Hugh

    2016-01-01

    The proliferation and activation of microglial cells is a hallmark of several neurodegenerative conditions. This mechanism is regulated by the activation of the colony-stimulating factor 1 receptor (CSF1R), thus providing a target that may prevent the progression of conditions such as Alzheimer’s disease. However, the study of microglial proliferation in Alzheimer’s disease and validation of the efficacy of CSF1R-inhibiting strategies have not yet been reported. In this study we found increased proliferation of microglial cells in human Alzheimer’s disease, in line with an increased upregulation of the CSF1R-dependent pro-mitogenic cascade, correlating with disease severity. Using a transgenic model of Alzheimer’s-like pathology (APPswe, PSEN1dE9; APP/PS1 mice) we define a CSF1R-dependent progressive increase in microglial proliferation, in the proximity of amyloid-β plaques. Prolonged inhibition of CSF1R in APP/PS1 mice by an orally available tyrosine kinase inhibitor (GW2580) resulted in the blockade of microglial proliferation and the shifting of the microglial inflammatory profile to an anti-inflammatory phenotype. Pharmacological targeting of CSF1R in APP/PS1 mice resulted in an improved performance in memory and behavioural tasks and a prevention of synaptic degeneration, although these changes were not correlated with a change in the number of amyloid-β plaques. Our results provide the first proof of the efficacy of CSF1R inhibition in models of Alzheimer’s disease, and validate the application of a therapeutic strategy aimed at modifying CSF1R activation as a promising approach to tackle microglial activation and the progression of Alzheimer’s disease. PMID:26747862

  18. Pharmacological targeting of CSF1R inhibits microglial proliferation and prevents the progression of Alzheimer's-like pathology.

    PubMed

    Olmos-Alonso, Adrian; Schetters, Sjoerd T T; Sri, Sarmi; Askew, Katharine; Mancuso, Renzo; Vargas-Caballero, Mariana; Holscher, Christian; Perry, V Hugh; Gomez-Nicola, Diego

    2016-03-01

    The proliferation and activation of microglial cells is a hallmark of several neurodegenerative conditions. This mechanism is regulated by the activation of the colony-stimulating factor 1 receptor (CSF1R), thus providing a target that may prevent the progression of conditions such as Alzheimer's disease. However, the study of microglial proliferation in Alzheimer's disease and validation of the efficacy of CSF1R-inhibiting strategies have not yet been reported. In this study we found increased proliferation of microglial cells in human Alzheimer's disease, in line with an increased upregulation of the CSF1R-dependent pro-mitogenic cascade, correlating with disease severity. Using a transgenic model of Alzheimer's-like pathology (APPswe, PSEN1dE9; APP/PS1 mice) we define a CSF1R-dependent progressive increase in microglial proliferation, in the proximity of amyloid-β plaques. Prolonged inhibition of CSF1R in APP/PS1 mice by an orally available tyrosine kinase inhibitor (GW2580) resulted in the blockade of microglial proliferation and the shifting of the microglial inflammatory profile to an anti-inflammatory phenotype. Pharmacological targeting of CSF1R in APP/PS1 mice resulted in an improved performance in memory and behavioural tasks and a prevention of synaptic degeneration, although these changes were not correlated with a change in the number of amyloid-β plaques. Our results provide the first proof of the efficacy of CSF1R inhibition in models of Alzheimer's disease, and validate the application of a therapeutic strategy aimed at modifying CSF1R activation as a promising approach to tackle microglial activation and the progression of Alzheimer's disease. PMID:26747862

  19. Microglial interleukin-1β in the ipsilateral dorsal horn inhibits the development of mirror-image contralateral mechanical allodynia through astrocyte activation in a rat model of inflammatory pain.

    PubMed

    Choi, Hoon-Seong; Roh, Dae-Hyun; Yoon, Seo-Yeon; Moon, Ji-Young; Choi, Sheu-Ran; Kwon, Soon-Gu; Kang, Suk-Yun; Han, Ho-Jae; Kim, Hyun-Woo; Beitz, Alvin J; Oh, Seog-Bae; Lee, Jang-Hern

    2015-06-01

    Damage on one side of the body can also result in pain on the contralateral unaffected side, called mirror-image pain (MIP). Currently, the mechanisms responsible for the development of MIP are unknown. In this study, we investigated the involvement of spinal microglia and interleukin-1β (IL-1β) in the development of MIP using a peripheral inflammatory pain model. After unilateral carrageenan injection, mechanical allodynia (MA) in both hind paws and the expression levels of spinal Iba-1, IL-1β, and GFAP were evaluated. Ipsilateral MA was induced beginning at 3 hours after carrageenan injection, whereas contralateral MA showed a delayed onset occurring 5 days after injection. A single intrathecal (i.t.) injection of minocycline, a tetracycline derivative that displays selective inhibition of microglial activation, or an interleukin-1 receptor antagonist (IL-1ra) on the day of carrageenan injection caused an early temporary induction of contralateral MA, whereas repeated i.t. treatment with these drugs from days 0 to 3 resulted in a long-lasting contralateral MA, which was evident in its advanced development. We further showed that IL-1β was localized to microglia and that minocycline inhibited the carrageenan-induced increases in spinal Iba-1 and IL-1β expression. Conversely, minocycline or IL-1ra pretreatment increased GFAP expression as compared with that of control rats. However, i.t. pretreatment with fluorocitrate, an astrocyte inhibitor, restored minocycline- or IL-1ra-induced contralateral MA. These results suggest that spinal IL-1β derived from activated microglia temporarily suppresses astrocyte activation, which can ultimately prevent the development of contralateral MA under inflammatory conditions. These findings imply that microglial IL-1β plays an important role in regulating the induction of inflammatory MIP. PMID:25749305

  20. microRNA-34a-Mediated Down-Regulation of the Microglial-Enriched Triggering Receptor and Phagocytosis-Sensor TREM2 in Age-Related Macular Degeneration

    PubMed Central

    Dua, Prerna; Rogaev, Evgeny I.; Lukiw, Walter J.

    2016-01-01

    The aggregation of Aβ42-peptides and the formation of drusen in age-related macular degeneration (AMD) are due in part to the inability of homeostatic phagocytic mechanisms to clear self-aggregating Aβ42-peptides from the extracellular space. The triggering receptor expressed in myeloid/microglial cells-2 (TREM2), a trans-membrane-spanning, sensor-receptor of the immune-globulin/lectin-like gene superfamily is a critical component of Aβ42-peptide clearance. Here we report a significant deficit in TREM2 in AMD retina and in cytokine- or oxidatively-stressed microglial (MG) cells. RT-PCR, miRNA-array, LED-Northern and Western blot studies indicated up-regulation of a microglial-enriched NF-кB-sensitive miRNA-34a coupled to a down-regulation of TREM2 in the same samples. Bioinformatics/transfection-luciferase reporter assays indicated that miRNA-34a targets the 299 nucleotide TREM2-mRNA-3’UTR, resulting in TREM2 down-regulation. C8B4-microglial cells challenged with Aβ42 were able to phagocytose these peptides, while miRNA-34a down-regulated both TREM2 and the ability of microglial-cells to phagocytose. Treatment of TNFα-stressed MG cells with phenyl-butyl nitrone (PBN), caffeic-acid phenethyl ester (CAPE), the NF-B-inhibitor/resveratrol analog CAY10512 or curcumin abrogated these responses. Incubation of anti-miRNA-34a (AM-34a) normalized miRNA-34a abundance and restored TREM2 back to homeostatic levels. These data support five novel observations: (i) that a ROS- and NF-B-sensitive, miRNA-34a-mediated modulation of TREM2 may in part regulate the phagocytic response; (ii) that gene products encoded on two different chromosomes (miRNA-34a at chr1q36.22 and TREM2 at chr6p21.1) orchestrate a phagocytic-Aβ42-peptide clearance-system; (iii) that this NF-kB-mediated-miRNA-34a-TREM2 mechanism is inducible from outside of the cell; (iv) that when operating normally, this pathway can clear Aβ42 peptide monomers from the extracellular medium; and (v) that anti

  1. microRNA-34a-Mediated Down-Regulation of the Microglial-Enriched Triggering Receptor and Phagocytosis-Sensor TREM2 in Age-Related Macular Degeneration.

    PubMed

    Bhattacharjee, Surjyadipta; Zhao, Yuhai; Dua, Prerna; Rogaev, Evgeny I; Lukiw, Walter J

    2016-01-01

    The aggregation of Aβ42-peptides and the formation of drusen in age-related macular degeneration (AMD) are due in part to the inability of homeostatic phagocytic mechanisms to clear self-aggregating Aβ42-peptides from the extracellular space. The triggering receptor expressed in myeloid/microglial cells-2 (TREM2), a trans-membrane-spanning, sensor-receptor of the immune-globulin/lectin-like gene superfamily is a critical component of Aβ42-peptide clearance. Here we report a significant deficit in TREM2 in AMD retina and in cytokine- or oxidatively-stressed microglial (MG) cells. RT-PCR, miRNA-array, LED-Northern and Western blot studies indicated up-regulation of a microglial-enriched NF-кB-sensitive miRNA-34a coupled to a down-regulation of TREM2 in the same samples. Bioinformatics/transfection-luciferase reporter assays indicated that miRNA-34a targets the 299 nucleotide TREM2-mRNA-3'UTR, resulting in TREM2 down-regulation. C8B4-microglial cells challenged with Aβ42 were able to phagocytose these peptides, while miRNA-34a down-regulated both TREM2 and the ability of microglial-cells to phagocytose. Treatment of TNFα-stressed MG cells with phenyl-butyl nitrone (PBN), caffeic-acid phenethyl ester (CAPE), the NF-kB - [corrected] inhibitor/resveratrol analog CAY10512 or curcumin abrogated these responses. Incubation of anti-miRNA-34a (AM-34a) normalized miRNA-34a abundance and restored TREM2 back to homeostatic levels. These data support five novel observations: (i) that a ROS- and NF-kB - [corrected] sensitive, miRNA-34a-mediated modulation of TREM2 may in part regulate the phagocytic response; (ii) that gene products encoded on two different chromosomes (miRNA-34a at chr1q36.22 and TREM2 at chr6p21.1) orchestrate a phagocytic-Aβ42-peptide clearance-system; (iii) that this NF-kB-mediated-miRNA-34a-TREM2 mechanism is inducible from outside of the cell; (iv) that when operating normally, this pathway can clear Aβ42 peptide monomers from the extracellular

  2. Development of the microglial phenotype in culture.

    PubMed

    Szabo, M; Gulya, K

    2013-06-25

    Selected morphological, molecular and functional aspects of various microglial cell populations were characterized in cell cultures established from the forebrains of E18 rat embryos. The mixed primary cortical cultures were maintained for up to 28days using routine culturing techniques when the microglial cells in the culture were not stimulated or immunologically challenged. During culturing, expansion of the microglial cell populations was observed, as evidenced by quantitative assessment of selected monocyte/macrophage/microglial cell-specific markers (human leukocyte antigen (HLA) DP, DQ, DR, CD11b/c and Iba1) via immunocyto- and histochemistry and Western blot analysis. The Iba1 immunoreactivity in Western blots steadily increased about 750-fold, and the number of Iba1-immunoreactive cells rose at least 67-fold between one day in vitro (DIV1) and DIV28. Morphometric analysis on binary (digital) silhouettes of the microglia revealed their evolving morphology during culturing. Microglial cells were mainly ameboid in the early stages of in vitro differentiation, while mixed populations of ameboid and ramified cell morphologies were characteristic of older cultures as the average transformation index (TI) increased from 1.96 (DIV1) to 15.17 (DIV28). Multiple immunofluorescence labeling of selected biomarkers revealed different microglial phenotypes during culturing. For example, while HLA DP, DQ, DR immunoreactivity was present exclusively in ameboid microglia (TI<3) between DIV1 and DIV10, CD11b/c- and Iba1-positive microglial cells were moderately (TI<13) and progressively (TI<81) more ramified, respectively, and always present throughout culturing. Regardless of the age of the cultures, proliferating microglia were Ki67-positive and characterized by low TI values (TI<3). The microglial function was assessed by an in vitro phagocytosis assay. Unstimulated microglia with low TI values were significantly more active in phagocytosing fluorescent microspheres than

  3. [Microglial Phagocytosis in the Neurodegenerative Diseases].

    PubMed

    Cao, Sheng-nan; Bao, Xiu-qi; Sun, Hua; Zhang, Dan

    2016-04-01

    Microglia are the resident innate immune cells in the brain. Under endogenous or exogenous stimulates, they become activated and play an important role in the neurodegenerative diseases. Microglial phagocytosis is a process of receptor-mediated engulfment and degradation of apoptotic cells. In addition, microglia can phagocyte brain-specific cargo, such as myelin debris and abnormal protein aggregation. However, recent studies have shown that microglia can also phagocyte stressed-but-viable neurons, causing loss of neurons in the brain. Thus, whether microglial phagocytosis is beneficial or not in neurodegenerative disease remains controversial. This article reviews microglial phagocytosis related mechanisms and its potential roles in neurodegenerative diseases, with an attempt to provide new insights in the treatment of neurodegenerative diseases. PMID:27181903

  4. Dynamic changes in global microRNAome and transcriptome reveal complex miRNA-mRNA regulated host response to Japanese Encephalitis Virus in microglial cells

    PubMed Central

    Kumari, Bharti; Jain, Pratistha; Das, Shaoli; Ghosal, Suman; Hazra, Bibhabasu; Trivedi, Ashish Chandra; Basu, Anirban; Chakrabarti, Jayprokas; Vrati, Sudhanshu; Banerjee, Arup

    2016-01-01

    Microglia cells in the brain play essential role during Japanese Encephalitis Virus (JEV) infection and may lead to change in microRNA (miRNA) and mRNA profile. These changes may together control disease outcome. Using Affymetrix microarray platform, we profiled cellular miRNA and mRNA expression at multiple time points during viral infection in human microglial (CHME3) cells. In silico analysis of microarray data revealed a phased pattern of miRNAs expression, associated with JEV replication and provided unique signatures of infection. Target prediction and pathway enrichment analysis identified anti correlation between differentially expressed miRNA and the gene expression at multiple time point which ultimately affected diverse signaling pathways including Notch signaling pathways in microglia. Activation of Notch pathway during JEV infection was demonstrated in vitro and in vivo. The expression of a subset of miRNAs that target multiple genes in Notch signaling pathways were suppressed and their overexpression could affect JEV induced immune response. Further analysis provided evidence for the possible presence of cellular competing endogenous RNA (ceRNA) associated with innate immune response. Collectively, our data provide a uniquely comprehensive view of the changes in the host miRNAs induced by JEV during cellular infection and identify Notch pathway in modulating microglia mediated inflammation. PMID:26838068

  5. Neurobiology of microglial action in CNS injuries: receptor-mediated signaling mechanisms and functional roles

    PubMed Central

    Hu, Xiaoming; Liou, Anthony K.F.; Leak, Rehana K.; Xu, Mingyue; An, Chengrui; Suenaga, Jun; Shi, Yejie; Gao, Yanqin; Zheng, Ping; Chen, Jun

    2014-01-01

    Microglia are the first line of immune defense against central nervous system (CNS) injuries and disorders. These highly plastic cells play dualistic roles in neuronal injury and recovery and are known for their ability to assume diverse phenotypes. A broad range of surface receptors are expressed on microglia and mediate microglial ‘On’ or ‘Off’ responses to signals from other host cells as well as invading microorganisms. The integrated actions of these receptors result in tightly regulated biological functions, including cell mobility, phagocytosis, the induction of acquired immunity, and trophic factor/inflammatory mediator release. Over the last few years, significant advances have been made towards deciphering the signaling mechanisms related to these receptors and their specific cellular functions. In this review, we describe the current state of knowledge of the surface receptors involved in microglial activation, with an emphasis on their engagement of distinct functional programs and their roles in CNS injuries. It will become evident from this review that microglial homeostasis is carefully maintained by multiple counterbalanced strategies, including, but not limited to, ‘On’ and ‘Off’ receptor signaling. Specific regulation of theses microglial receptors may be a promising therapeutic strategy against CNS injuries. PMID:24923657

  6. 2-Methoxyestradiol, an endogenous 17β-estradiol metabolite, inhibits microglial proliferation and activation via an estrogen receptor-independent mechanism.

    PubMed

    Schaufelberger, Sara A; Rosselli, Marinella; Barchiesi, Federica; Gillespie, Delbert G; Jackson, Edwin K; Dubey, Raghvendra K

    2016-03-01

    17β-Estradiol (estradiol) inhibits microglia proliferation. 2-Methoxyestradiol (2-ME) is an endogenous metabolite of estradiol with little affinity for estrogen receptors (ERs). We hypothesize that 2-ME inhibits microglial proliferation and activation and contributes to estradiol's inhibitory effects on microglia. We compared the effects of estradiol, 2-hydroxyestradiol [2-OE; estradiol metabolite produced by cytochrome P450 (CYP450)], and 2-ME [formed by catechol-O-methyltransferase (COMT) acting upon 2-OE] on microglial (BV2 cells) DNA synthesis, cell proliferation, activation, and phagocytosis. 2-ME and 2-OE were approximately three- and 10-fold, respectively, more potent than estradiol in inhibiting microglia DNA synthesis. The antimitogenic effects of estradiol were reduced by pharmacological inhibitors of CYP450 and COMT. Inhibition of COMT blocked the conversion of 2-OE to 2-ME and the antimitogenic effects of 2-OE but not 2-ME. Microglia expressed ERβ and GPR30 but not ERα. 2,3-Bis(4-hydroxyphenyl)-propionitrile (ERβ agonist), but not 4,4',4''-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (ERα agonist) or G1 (GPR30 agonist), inhibited microglial proliferation. The antiproliferative effects of estradiol, but not 2-OE or 2-ME, were partially reversed by ICI-182,780 (ERα/β antagonist) but not by 1,3-bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1H-pyrazole (ERα antagonist) or G15 (GPR30 antagonist). Lipopolysaccharide increased microglia iNOS and COX-2 expression and phagocytosing activity of microglia; these effects were inhibited by 2-ME. We conclude that in microglia, 2-ME inhibits proliferation, proinflammatory responses, and phagocytosis. 2-ME partially mediates the effects of estradiol via ER-independent mechanisms involving sequential metabolism of estradiol to 2-OE and 2-ME. 2-ME could be of potential therapeutic use in postischemic stroke injuries. Interindividual differences in estradiol metabolism might affect the

  7. A novel synthetic compound MCAP suppresses LPS-induced murine microglial activation in vitro via inhibiting NF-kB and p38 MAPK pathways

    PubMed Central

    Kim, Byung-Wook; More, Sandeep Vasant; Yun, Yo-Sep; Ko, Hyun-Myung; Kwak, Jae-Hwan; Lee, Heesoon; Suk, Kyoungho; Kim, In-Su; Choi, Dong-Kug

    2016-01-01

    Aim: To investigate the anti-neuroinflammatory activity of a novel synthetic compound, 7-methylchroman-2-carboxylic acid N-(2-trifluoromethyl) phenylamide (MCAP) against LPS-induced microglial activation in vitro. Methods: Primary mouse microglia and BV2 microglia cells were exposed to LPS (50 or 100 ng/mL). The expression of iNOS and COX-2, proinflammatory cytokines, NF-κB and p38 MAPK signaling molecules were analyzed by RT-PCR, Western blot and ELISA. The morphological changes of microglia and nuclear translocation of NF-ĸB were visualized using phase contrast and fluorescence microscopy, respectively. Results: Pretreatment with MCAP (0.1, 1, 10 μmol/L) dose-dependently inhibited LPS-induced expression of iNOS and COX-2 in BV2 microglia cells. Similar results were obtained in primary microglia pretreated with MCAP (0.1, 0.5 μmol/L). MCAP dose-dependently abated LPS-induced release of TNF-α, IL-6 and IL-1β, and mitigated LPS-induced activation of NF-κB by reducing the phosphorylation of IκBα in BV2 microglia cells. Moreover, MCAP attenuated LPS-induced phosphorylation of p38 MAPK, whereas SB203580, a p38 MAPK inhibitor, significantly potentiated MCAP-caused inhibition on the expression of MEF-2 (a transcription factor downstream of p38 MAPK). Conclusion: MCAP exerts anti-inflammatory effects in murine microglia in vitro by inhibiting the p38 MAPK and NF-κB signaling pathways and proinflammatory responses. MCAP may be developed as a novel agent for treating diseases involving activated microglial cells. PMID:26838070

  8. Anti-Inflammatory Activity of Bee Venom in BV2 Microglial Cells: Mediation of MyD88-Dependent NF-κB Signaling Pathway

    PubMed Central

    Kim, Su Jung; Hong, Seung Bok; Park, Jin-Kyu

    2016-01-01

    Bee venom has long been used as a traditional folk medicine in Korea. It has been reportedly used for the treatment of arthritis, cancer, and inflammation. Although its anti-inflammatory activity in lipopolysaccharide- (LPS-) stimulated inflammatory cells has been reported, the exact mechanism of its anti-inflammatory action has not been fully elucidated. Therefore, the aim of this study was to investigate the anti-inflammatory mechanism of bee venom in BV2 microglial cells. We first investigated whether NO production in LPS-activated BV2 cells was inhibited by bee venom, and further iNOS mRNA and protein expressions were determined. The mRNA and protein levels of proinflammatory cytokines were examined using semiquantitative RT-PCR and immunoblotting, respectively. Moreover, modulation of the transcription factor NF-κB by bee venom was also investigated using a luciferase assay. LPS-induced NO production in BV2 microglial cells was significantly inhibited in a concentration-dependent manner upon pretreatment with bee venom. Bee venom markedly reduced the mRNA expression of COX-2, TNF-α, IL-1β, and IL-6 and suppressed LPS-induced activation of MyD88 and IRAK1 and phosphorylation of TAK1. Moreover, NF-κB translocation by IKKα/β phosphorylation and subsequent IκB-α degradation were also attenuated. Thus, collectively, these results indicate that bee venom exerts its anti-inflammatory activity via the IRAK1/TAK1/NF-κB signaling pathway. PMID:27563334

  9. Anti-Inflammatory Activity of Bee Venom in BV2 Microglial Cells: Mediation of MyD88-Dependent NF-κB Signaling Pathway.

    PubMed

    Im, Eun Ju; Kim, Su Jung; Hong, Seung Bok; Park, Jin-Kyu; Rhee, Man Hee

    2016-01-01

    Bee venom has long been used as a traditional folk medicine in Korea. It has been reportedly used for the treatment of arthritis, cancer, and inflammation. Although its anti-inflammatory activity in lipopolysaccharide- (LPS-) stimulated inflammatory cells has been reported, the exact mechanism of its anti-inflammatory action has not been fully elucidated. Therefore, the aim of this study was to investigate the anti-inflammatory mechanism of bee venom in BV2 microglial cells. We first investigated whether NO production in LPS-activated BV2 cells was inhibited by bee venom, and further iNOS mRNA and protein expressions were determined. The mRNA and protein levels of proinflammatory cytokines were examined using semiquantitative RT-PCR and immunoblotting, respectively. Moreover, modulation of the transcription factor NF-κB by bee venom was also investigated using a luciferase assay. LPS-induced NO production in BV2 microglial cells was significantly inhibited in a concentration-dependent manner upon pretreatment with bee venom. Bee venom markedly reduced the mRNA expression of COX-2, TNF-α, IL-1β, and IL-6 and suppressed LPS-induced activation of MyD88 and IRAK1 and phosphorylation of TAK1. Moreover, NF-κB translocation by IKKα/β phosphorylation and subsequent IκB-α degradation were also attenuated. Thus, collectively, these results indicate that bee venom exerts its anti-inflammatory activity via the IRAK1/TAK1/NF-κB signaling pathway. PMID:27563334

  10. Shenqi Fuzheng Injection attenuates irradiation-induced brain injury in mice via inhibition of the NF-κB signaling pathway and microglial activation

    PubMed Central

    Zhang, Jian; Tong, Fan; Cai, Qian; Chen, Ling-juan; Dong, Ji-hua; Wu, Gang; Dong, Xiao-rong

    2015-01-01

    Aim: Radiation-induced brain injury (RIBI) is the most common and severe adverse effect induced by cranial radiation therapy (CRT). In the present study, we examined the effects of the traditional Chinese medicine Shenqi Fuzheng Injection (SFI) on RIBI in mice, and explored the underlying mechanisms. Methods: C57BL/6J mice were subjected to a single dose of 20-Gy CRT. The mice were treated with SFI (20 mL·kg-1·d-1, ip) for 4 weeks. Morris water maze test was used to assess the cognitive changes. Evans blue leakage and a horseradish peroxidase (HRP) assay were used to evaluate the integrity of the blood-brain barrier (BBB). The expression of inflammatory factors and microglial activation in brain tissues were detected using RT-PCR, Western blotting and immunofluorescence staining. Results: CRT caused marked reductions in the body weight and life span of the mice, and significantly impaired their spatial learning. Furthermore, CRT significantly increased the BBB permeability, number of activated microglia, expression levels of TNF-α and IL-1β, and the levels of phosphorylated p65 and PIDD-CC (the twice-cleaved fragment of p53-induced protein with a death domain) in the brain tissues. Four-week SFI treatment (administered for 2 weeks before and 2 weeks after CRT) not only significantly improved the physical status, survival, and spatial learning in CRT-treated mice, but also attenuated all the CRT-induced changes in the brain tissues. Four-week SFI pretreatment (administered for 4 weeks before CRT) was less effective. Conclusion: Administration of SFI effectively attenuates irradiation-induced brain injury via inhibition of the NF-κB signaling pathway and microglial activation. PMID:26526200

  11. Time-dependent retinal ganglion cell loss, microglial activation and blood-retina-barrier tightness in an acute model of ocular hypertension.

    PubMed

    Trost, A; Motloch, K; Bruckner, D; Schroedl, F; Bogner, B; Kaser-Eichberger, A; Runge, C; Strohmaier, C; Klein, B; Aigner, L; Reitsamer, H A

    2015-07-01

    Glaucoma is a group of neurodegenerative diseases characterized by the progressive loss of retinal ganglion cells (RGCs) and their axons, and is the second leading cause of blindness worldwide. Elevated intraocular pressure is a well known risk factor for the development of glaucomatous optic neuropathy and pharmacological or surgical lowering of intraocular pressure represents a standard procedure in glaucoma treatment. However, the treatment options are limited and although lowering of intraocular pressure impedes disease progression, glaucoma cannot be cured by the currently available therapy concepts. In an acute short-term ocular hypertension model in rat, we characterize RGC loss, but also microglial cell activation and vascular alterations of the retina at certain time points. The combination of these three parameters might facilitate a better evaluation of the disease progression, and could further serve as a new model to test novel treatment strategies at certain time points. Acute ocular hypertension (OHT) was induced by the injection of magnetic microbeads into the rat anterior chamber angle (n = 22) with magnetic position control, leading to constant elevation of IOP. At certain time points post injection (4d, 7d, 10d, 14d and 21d), RGC loss, microglial activation, and microvascular pericyte (PC) coverage was analyzed using immunohistochemistry with corresponding specific markers (Brn3a, Iba1, NG2). Additionally, the tightness of the retinal vasculature was determined via injections of Texas Red labeled dextran (10 kDa) and subsequently analyzed for vascular leakage. For documentation, confocal laser-scanning microscopy was used, followed by cell counts, capillary length measurements and morphological and statistical analysis. The injection of magnetic microbeads led to a progressive loss of RGCs at the five time points investigated (20.07%, 29.52%, 41.80%, 61.40% and 76.57%). Microglial cells increased in number and displayed an activated morphology

  12. Microglial response to amyloid plaques in APPsw transgenic mice.

    PubMed Central

    Frautschy, S. A.; Yang, F.; Irrizarry, M.; Hyman, B.; Saido, T. C.; Hsiao, K.; Cole, G. M.

    1998-01-01

    Microglial activation is central to the inflammatory response in Alzheimer's Disease (AD). A recently described mouse line, Tg(HuAPP695.K670N/M671L)2576, expressing human amyloid precursor protein with a familial AD gene mutation, age-related amyloid deposits, and memory deficits, was found to develop a significant microglial response using Griffonia simplicifolia lectin or phosphotyrosine probe to identify microglia Both Griffonia simplicifolia lectin and phosphotyrosine staining showed increased numbers of intensely labeled, often enlarged microglia clustered in and around plaques, consistent with microglial activation related to beta-amyloid formation. Using quantitative image analysis of coronal phosphotyrosine-immunostained sections, transgene-positive 10- to 16-month-old, hemizygous, hybrid Tg2576 (APPsw) animals showed significantly increased microglial density and size in plaque-forming areas of hippocampus and frontal, entorhinal, and occipital cortex. Quantitative analysis of microglia as a function of distance from the center of plaques (double labeled for A beta peptide and microglia) revealed highly significant, two- to fivefold elevations in microglial number and area within plaques compared with neighboring regions. Tg2576 beta-amyloid-plaque-forming mice should be a useful system for assessing the consequences of the microglial-mediated inflammatory response to beta-amyloid and developing anti-inflammatory therapeutic strategies for Alzheimer's disease. These results provide the first quantitative link between beta-amyloid plaque formation and microglial activation in an animal model with neuritic plaques and memory deficits. Images Figure 1 Figure 2 PMID:9422548

  13. Effect of CCL2 on BV2 microglial cell migration: Involvement of probable signaling pathways.

    PubMed

    Bose, Shambhunath; Kim, Sunyoung; Oh, Yeonsoo; Moniruzzaman, Md; Lee, Gyeongjun; Cho, Jungsook

    2016-05-01

    Microglia, the resident macrophages of the central nervous system, play a vital role in the regulation of innate immune function and neuronal homeostasis of the brain. Currently, much interest is being generated regarding the investigation of the microglial migration that results in their accumulation at focal sites of injury. Chemokines including CCL2 are known to cause the potential induction of migration of microglial cells, although the underlying mechanisms are not well understood. In the present study, using murine neonatal BV2 microglial cells as a model, we investigate the impact of CCL2 on the migration of microglial cells and address the probable molecular events within the cellular signaling cascades mediating CCL2-induced cell migration. Our results demonstrate concentration- and time-dependent induction of BV2 cell migration by CCL2 and reveal complex mechanisms involving the activation of MEK, ERK1/2, and Akt, and their cross-talk. In addition, we demonstrate that the MEK/ERK pathway activated by CCL2 treatment mediate p90RSK activation in BV2 cells. Moreover, our findings indicate that Akt, ERK1/2, and p90RSK are the downstream effectors of PI3K in the CCL2-induced signaling. Finally, phosphorylation of the transcription factors c-jun and ATF-1 is found to be a further downstream signaling cascade in the CCL2-mediated action. Our results suggest that CCL2-induced activation of c-jun and ATF-1 is likely to be linked to the MEK/ERK and PI3K signaling pathways, respectively. Taken together, these findings contribute to a better understanding of CCL2-induced microglial migration and the probable signaling pathways involved. PMID:26878647

  14. Age-Related Differences in Neuropathic Pain Behavior and Spinal Microglial Activity after L5 Spinal Nerve Ligation in Male Rats

    PubMed Central

    Zeinali, Hossein; Manaheji, Homa; Zaringhalam, Jalal; Bahari, Zahra; Nazemi, Samad; Sadeghi, Mehdi

    2016-01-01

    Introduction: Several studies have reported the involvement of age-related changes in the development of neuropathic pain behaviors. However, limited data are available on the role of age in establishing and maintaining chronic neuropathic pain after peripheral nerve injury. Methods: In the present study, we examined age-related neuropathic behavior among rats in 4 age groups: pups (4 weeks old; weight, 60–80 g), juvenile rats (6 weeks old; weight, 120–140 g), and mature rats (10–12 weeks old; weight, 200–250 g). Because the exact contribution of spinal microglia and its association with the development of neuropathic pain remains unknown, we also evaluated the expression of spinal Iba1, a microglial marker, by using western blotting before and 5 days after spinal nerve ligation (SNL) as well as after the daily IP administration of minocycline (30 mg/kg). Results: Our results showed that SNL-induced mechanical allodynia but not thermal hyperalgesia in mature rats but not in pups (P<0.05 and P<0.01, respectively). The expression of spinal Iba1 in the juvenile rats was significantly lower than that in pups and mature rats (P<0.01). Moreover, administration of minocycline decreased the expression of spinal Iba1 in the pup rats more than in juvenile rats (P<0.001) and in the juvenile rats more than in the mature rats (P<0.05). Conclusion: These data suggest that the development of neuropathic behaviors and microglial activation after SNL could be age dependent. PMID:27563413

  15. Anti-neuro-inflammatory effects of Nardostachys chinensis in lipopolysaccharide-and lipoteichoic acid-stimulated microglial cells.

    PubMed

    Park, Sun Young; Kim, Young Hun; Park, Geuntae

    2016-05-01

    Excessive microglial cell activation is related to the progression of chronic neuro-inflammatory disorders. Heme oxygenase-1 (HO-1) expression mediated by the NFE2-related factor (Nrf-2) pathway is a key regulator of neuro-inflammation. Nardostachys chinensis is used as an anti-malarial, anti-nociceptive, and neurotrophic treatment in traditional Asian medicines. In the present study, we examined the effects of an ethyl acetate extract of N. chinensis (EN) on the anti-neuro-inflammatory effects mediated by HO-1 up-regulation in Salmonella lipopolysaccharide (LPS)- or Staphylococcus aureus lipoteichoic acid (LTA)-stimulated BV2 microglial cells. Our results indicated that EN suppressed pro-inflammatory cytokine production and induced HO-1 transcription and translation through Nrf-2/antioxidant response element (ARE) signaling. EN markedly inhibited LPS- and LTA-induced activation of nuclear factor-kappa B (NF-κB) as well as phosphorylation of mitogen-activated protein kinases (MAPKs) and signal transducer and activator of transcription (STAT). Furthermore, EN protected hippocampal HT22 cells from indirect neuronal toxicity mediated by LPS- and LTA-treated microglial cells. These results suggested that EN impairs LPS- and LTA-induced neuro-inflammatory responses in microglial cells and confers protection against indirect neuronal damage to HT22 cells. In conclusion, our findings indicate that EN could be used as a natural anti-neuro-inflammatory and neuroprotective agent. PMID:27478097

  16. A novel role of microglial NADPH oxidase in mediating extra-synaptic function of norepinephrine in regulating brain immune homeostasis.

    PubMed

    Jiang, Lulu; Chen, Shih-Heng; Chu, Chun-Hsien; Wang, Shi-Jun; Oyarzabal, Esteban; Wilson, Belinda; Sanders, Virginia; Xie, Keqin; Wang, Qingshan; Hong, Jau-Shyong

    2015-06-01

    Although the peripheral anti-inflammatory effect of norepinephrine (NE) is well documented, the mechanism by which this neurotransmitter functions as an anti-inflammatory/neuroprotective agent in the central nervous system (CNS) is unclear. This article aimed to determine the anti-inflammatory/neuroprotective effects and underlying mechanisms of NE in inflammation-based dopaminergic neurotoxicity models. In mice, NE-depleting toxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) was injected at 6 months of lipopolysaccharide (LPS)-induced neuroinflammation. It was found that NE depletion enhanced LPS-induced dopaminergic neuron loss in the substantia nigra. This piece of in vivo data prompted us to conduct a series of studies in an effort to elucidate the mechanism as to how NE affects dopamine neuron survival by using primary midbrain neuron/glia cultures. Results showed that submicromolar concentrations of NE dose-dependently protected dopaminergic neurons from LPS-induced neurotoxicity by inhibiting microglia activation and subsequent release of pro-inflammatory factors. However, NE-elicited neuroprotection was not totally abolished in cultures from β2-adrenergic receptor (β2-AR)-deficient mice, suggesting that novel pathways other than β2-AR are involved. To this end, It was found that submicromolar NE dose-dependently inhibited NADPH oxidase (NOX2)-generated superoxide, which contributes to the anti-inflammatory and neuroprotective effects of NE. This novel mechanism was indeed adrenergic receptors independent since both (+) and (-) optic isomers of NE displayed the same potency. We further demonstrated that NE inhibited LPS-induced NOX2 activation by blocking the translocation of its cytosolic subunit to plasma membranes. In summary, we revealed a potential physiological role of NE in maintaining brain immune homeostasis and protecting neurons via a novel mechanism. PMID:25740080

  17. A novel role of microglial NADPH oxidase in mediating extra-synaptic function of norepinephrine in regulating brain immune homeostasis

    PubMed Central

    Jiang, Lulu; Chen, Shih-Heng; Chu, Chun-Hsien; Wang, Shi-Jun; Oyarzabal, Esteban; Wilson, Belinda; Sanders, Virginia; Xie, Keqin; Wang, Qingshan; Hong, Jau-Shyong

    2015-01-01

    Although the peripheral anti-inflammatory effect of norepinephrine (NE) is well-documented, the mechanism by which this neurotransmitter functions as an anti-inflammatory/neuroprotective agent in the central nervous system is unclear. This study aimed to determine the anti-inflammatory/neuroprotective effects and underlying mechanisms of NE in inflammation-based dopaminergic neurotoxicity models. In mice, NE-depleting toxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) was injected at 6 months of lipopolysaccharide (LPS)-induced neuroinflammation. We found that NE depletion enhanced LPS-induced dopaminergic neuron loss in the substantia nigra. This piece of in vivo data prompted us to conduct a series of studies in an effort to elucidate the mechanism as to how NE affects dopamine neuron survival by using primary midbrain neuron-glia cultures. Results showed that sub-micromolar concentrations of NE dose-dependently protected dopaminergic neurons from LPS-induced neurotoxicity by inhibiting microglia activation and subsequent release of pro-inflammatory factors. However, NE-elicited neuroprotection was not totally abolished in cultures from β2-adrenergic receptor (β2-AR) deficient mice, suggesting that novel pathways other than β2-AR are involved. To this end, we found that sub-micromolar NE dose-dependently inhibited NADPH oxidase (NOX2)-generated superoxide, which contributes to the anti-inflammatory and neuroprotective effects of NE. This novel mechanism was indeed adrenergic receptors independent since both (+) and (−) optic isomers of NE displayed the same potency. We further demonstrated that NE inhibited LPS-induced NOX2 activation by blocking the translocation of its cytosolic subunit to plasma membranes. In summary, we revealed a potential physiological role of NE in maintaining brain immune homeostasis and protecting neurons via a novel mechanism. PMID:25740080

  18. Activation of Intrinsic Immune Responses and Microglial Phagocytosis in an Ex Vivo Spinal Cord Slice Culture Model of West Nile Virus Infection

    PubMed Central

    Quick, Eamon D.; Leser, J. Smith; Tyler, Kenneth L.

    2014-01-01

    ABSTRACT West Nile virus (WNV) is a neurotropic flavivirus that causes significant neuroinvasive disease involving the brain and/or spinal cord. Experimental mouse models of WNV infection have established the importance of innate and adaptive immune responses in controlling the extent and severity of central nervous system (CNS) disease. However, differentiating between immune responses that are intrinsic to the CNS and those that are dependent on infiltrating inflammatory cells has proven difficult. We used a murine ex vivo spinal cord slice culture (SCSC) model to determine the innate immune processes specific to the CNS during WNV infections. By 7 days after ex vivo infection of SCSCs, the majority of neurons and a substantial percentage of astrocytes were infected with WNV, resulting in apoptotic cell death and astrogliosis. Microglia, the resident immune cells of the CNS, were activated by WNV infection, as exemplified by their amoeboid morphology, the development of filopodia and lamellipodia, and phagocytosis of WNV-infected cells and debris. Microglial cell activation was concomitant with increased expression of proinflammatory cytokines and chemokines, including CXCL10, CXCL1, CCL5, CCL3, CCL2, tumor necrosis factor alpha (TNF-α), TNF-related apoptosis-inducing ligand (TRAIL), and interleukin-6 (IL-6). The application of minocycline, an inhibitor of neuroinflammation, altered the WNV-induced proinflammatory cytokine/chemokine expression profile, with inhibited production of CCL5, CCL2, and IL-6. Our findings establish that CNS-resident cells have the capacity to initiate a robust innate immune response against WNV infection in the absence of infiltrating inflammatory cells and systemic immune responses. IMPORTANCE There are no specific treatments of proven efficacy available for WNV neuroinvasive disease. A better understanding of the pathogenesis of WNV CNS infection is crucial for the rational development of novel therapies. Development of a spinal cord

  19. Microglial Dynamics and Role in the Healthy and Diseased Brain

    PubMed Central

    Perry, V. Hugh

    2015-01-01

    The study of the dynamics and functions of microglia in the healthy and diseased brain is a matter of intense scientific activity. The application of new techniques and new experimental approaches has allowed the identification of novel microglial functions and the redefinition of classic ones. In this review, we propose the study of microglial functions, rather than their molecular profiles, to better understand and define the roles of these cells in the brain. We review current knowledge on the role of surveillant microglia, proliferating microglia, pruning/neuromodulatory microglia, phagocytic microglia, and inflammatory microglia and the molecular profiles that are associated with these functions. In the remodeling scenario of microglial biology, the analysis of microglial functional states will inform about the roles in health and disease and will guide us to a more precise understanding of the multifaceted roles of this never-resting cells. PMID:24722525

  20. [Nle4, D-Phe7]-α-MSH Inhibits Toll-Like Receptor (TLR)2- and TLR4-Induced Microglial Activation and Promotes a M2-Like Phenotype

    PubMed Central

    Carniglia, Lila; Ramírez, Delia; Durand, Daniela; Saba, Julieta; Caruso, Carla; Lasaga, Mercedes

    2016-01-01

    α-melanocyte stimulating hormone (α-MSH) is an anti-inflammatory peptide, proved to be beneficial in many neuroinflammatory disorders acting through melanocortin receptor 4 (MC4R). We previously determined that rat microglial cells express MC4R and that NDP-MSH, an analog of α-MSH, induces PPAR-γ expression and IL-10 release in these cells. Given the great importance of modulation of glial activation in neuroinflammatory disorders, we tested the ability of NDP-MSH to shape microglial phenotype and to modulate Toll-like receptor (TLR)-mediated inflammatory responses. Primary rat cultured microglia were stimulated with NDP-MSH followed by the TLR2 agonist Pam3CSK4 or the TLR4 agonist LPS. NDP-MSH alone induced expression of the M2a/M2c marker Ag1 and reduced expression of the M2b marker Il-4rα and of the LPS receptor Tlr4. Nuclear translocation of NF-κB subunits p65 and c-Rel was induced by LPS and these effects were partially prevented by NDP-MSH. NDP-MSH reduced LPS- and Pam3CSK4-induced TNF-α release but did not affect TLR-induced IL-10 release. Also, NDP-MSH inhibited TLR2-induced HMGB1 translocation from nucleus to cytoplasm and TLR2-induced phagocytic activity. Our data show that NDP-MSH inhibits TLR2- and TLR4-mediated proinflammatory mechanisms and promotes microglial M2-like polarization, supporting melanocortins as useful tools for shaping microglial activation towards an alternative immunomodulatory phenotype. PMID:27359332

  1. Activation of microglial cells triggers a release of brain-derived neurotrophic factor (BDNF) inducing their proliferation in an adenosine A2A receptor-dependent manner: A2A receptor blockade prevents BDNF release and proliferation of microglia

    PubMed Central

    2013-01-01

    Background Brain-derived neurotrophic factor (BDNF) has been shown to control microglial responses in neuropathic pain. Since adenosine A2A receptors (A2ARs) control neuroinflammation, as well as the production and function of BDNF, we tested to see if A2AR controls the microglia-dependent secretion of BDNF and the proliferation of microglial cells, a crucial event in neuroinflammation. Methods Murine N9 microglial cells were challenged with lipopolysaccharide (LPS, 100 ng/mL) in the absence or in the presence of the A2AR antagonist, SCH58261 (50 nM), as well as other modulators of A2AR signaling. The BDNF cellular content and secretion were quantified by Western blotting and ELISA, A2AR density was probed by Western blotting and immunocytochemistry and cell proliferation was assessed by BrdU incorporation. Additionally, the A2AR modulation of LPS-driven cell proliferation was also tested in primary cultures of mouse microglia. Results LPS induced time-dependent changes of the intra- and extracellular levels of BDNF and increased microglial proliferation. The maximal LPS-induced BDNF release was time-coincident with an LPS-induced increase of the A2AR density. Notably, removing endogenous extracellular adenosine or blocking A2AR prevented the LPS-mediated increase of both BDNF secretion and proliferation, as well as exogenous BDNF-induced proliferation. Conclusions We conclude that A2AR activation plays a mandatory role controlling the release of BDNF from activated microglia, as well as the autocrine/paracrine proliferative role of BDNF. PMID:23363775

  2. Microglial Dysregulation in Psychiatric Disease

    PubMed Central

    Frick, Luciana Romina; Williams, Kyle

    2013-01-01

    Microglia, the brain's resident immune cells, are phagocytes of the macrophage lineage that have a key role in responding to inflammation and immune challenge in the brain. More recently, they have been shown to have a number of important roles beyond immune surveillance and response, including synaptic pruning during development and the support of adult neurogenesis. Microglial abnormalities have been found in several neuropsychiatric conditions, though in most cases it remains unclear whether these are causative or are a reaction to some other underlying pathophysiology. Here we summarize postmortem, animal, neuroimaging, and other evidence for microglial pathology in major depression, schizophrenia, autism, obsessive-compulsive disorder, and Tourette syndrome. We identify gaps in the existing literature and important areas for future research. If microglial pathology proves to be an important causative factor in these or other neuropsychiatric diseases, modulators of microglial function may represent a novel therapeutic strategy. PMID:23690824

  3. Is traumatic axonal injury (AI) associated with an early microglial activation? Application of a double-labeling technique for simultaneous detection of microglia and AI.

    PubMed

    Oehmichen, M; Theuerkauf, I; Meissner, C

    1999-05-01

    The aim of the present study was to determine whether axonal injury (AI) induces a microglial reaction within 15 days after brain trauma. In 40 selected cases of confirmed AI, the topographical relation of AI and microglial reaction was assessed using an immunohistochemical double-labeling technique for simultaneous demonstration of AI using beta-amyloid precursor protein (beta-APP) antibody and of microglia using CD68 antibody. Although traumatic injury was usually followed by a moderate early diffuse rise in the number of CD68-reactive cells in the white matter, increases in macrophages in areas of AI accumulation were only sporadic and did not occur until after 4 days. At survival intervals of 5-15 days a moderate microglial reaction in regions of beta-APP-positive injured axons was detected, at maximum, in half of the case material. During this interval AI-associated satellitosis-like clusters or stars described by other authors after a survival time of more than 7 weeks were an isolated phenomenon. The prolonged microglial reaction as well as the reduction of beta-APP-positive AI during longer survival periods supports the hypothesis that AI is not primarily chemotactically attractive and that the damage to a portion of beta-APPstained axons may be partly reversible. Most cases clearly require a prolonged interval of more than 15 days before initiation of the final scavenger reaction. For forensic purposes the increase in the number of microglial cells within the region of AI accumulation after a survival time of more than 5 days and the multiple and distinct demonstration of star-like microglial reactions within the white matter after survival times exceeding 7 weeks may provide valuable postmortem information on the timing of a traumatic event. PMID:10334486

  4. Microglial dysfunction connects depression and Alzheimer's disease.

    PubMed

    Santos, Luís Eduardo; Beckman, Danielle; Ferreira, Sergio T

    2016-07-01

    Alzheimer's disease (AD) and major depressive disorder (MDD) are highly prevalent neuropsychiatric conditions with intriguing epidemiological overlaps. Depressed patients are at increased risk of developing late-onset AD, and around one in four AD patients are co-diagnosed with MDD. Microglia are the main cellular effectors of innate immunity in the brain, and their activation is central to neuroinflammation - a ubiquitous process in brain pathology, thought to be a causal factor of both AD and MDD. Microglia serve several physiological functions, including roles in synaptic plasticity and neurogenesis, which may be disrupted in neuroinflammation. Following early work on the 'sickness behavior' of humans and other animals, microglia-derived inflammatory cytokines have been shown to produce depressive-like symptoms when administered exogenously or released in response to infection. MDD patients consistently show increased circulating levels of pro-inflammatory cytokines, and anti-inflammatory drugs show promise for treating depression. Activated microglia are abundant in the AD brain, and concentrate around senile plaques, hallmark lesions composed of aggregated amyloid-β peptide (Aβ). The Aβ burden in affected brains is regulated largely by microglial clearance, and the complex activation state of microglia may be crucial for AD progression. Intriguingly, recent reports have linked soluble Aβ oligomers, toxins that accumulate in AD brains and are thought to cause memory impairment, to increased brain cytokine production and depressive-like behavior in mice. Here, we review recent findings supporting the inflammatory hypotheses of AD and MDD, focusing on microglia as a common player and therapeutic target linking these devastating disorders. PMID:26612494

  5. Minocycline, an antibiotic with inhibitory effect on microglial activation, attenuates the maintenance and reinstatement of methamphetamine-seeking behavior in rat.

    PubMed

    Attarzadeh-Yazdi, Ghassem; Arezoomandan, Reza; Haghparast, Abbas

    2014-08-01

    Methamphetamine (METH) is a major criminal justice and public health problem. Repeated use of METH causes dependence in humans and there are currently no particular pharmacological treatments for METH addiction. Glial cell activation is linked with METH abuse and METH administration causes activation of these cells in many areas of the brain. Many studies have demonstrated that glial cell modulators can modulate drug abuse effects. In this study, we examined the effect of the putative microglial inhibitor, minocycline on maintenance and prime-induced reinstatement of METH seeking behavior using the conditioned place preference (CPP) paradigm. CPP induced with METH (1 mg/kg, i.p. for 3 days) lasted for 11 days after cessation of METH treatment and priming dose of METH (0.5 mg/kg, i.p.) reinstated the extinguished METH-induced CPP. Daily treatment of minocycline (40 mg/kg, i.p.) followed by establishment of CPP blocked the maintenance of METH-induced CPP and also could attenuate priming-induced reinstatement. Furthermore, daily bilateral intra-accumbal injection of minocycline (10 and 20 μg/0.5 μl saline), during extinction period blocked the maintenance of METH CPP but just the highest dose of that could attenuate priming-induced reinstatement. We showed that minocycline administration during extinction period could facilitate extinction and maybe abolish the ability of drug-related cues evoke reinstatement, suggesting that minocycline might be considered as a promising therapeutic agent in preventing relapse in METH dependent individuals. PMID:24768984

  6. Morin downregulates nitric oxide and prostaglandin E2 production in LPS-stimulated BV2 microglial cells by suppressing NF-κB activity and activating HO-1 induction.

    PubMed

    Dilshara, Matharage Gayani; Jayasooriya, Rajapaksha Gedara Prasad Tharanga; Lee, Seungheon; Choi, Yung Hyun; Kim, Gi-Young

    2016-06-01

    Morin possesses anti-inflammatory activity against septic shock and allergic responses, and prevents acute liver damage. However, the biological mechanism of action of morin in neuroinflammation remains largely unknown. Therefore, the present study investigated whether morin has the ability to attenuate expression of proinflammatory mediators such as nitric oxide (NO) and prostaglandin E2 (PGE2) in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. Morin inhibited the expression of LPS-induced proinflammatory mediators such as NO and PGE2, without any cytotoxic effects. Furthermore, LPS-induced inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) were inhibited both at the mRNA and protein levels in response to morin. Morin also attenuated LPS-induced DNA-binding activity of nuclear transcription factor-κB (NF-κB) and its promoter activity. Pyrrolidine dithiocarbamate (PDTC), a specific NF-κB inhibitor, downregulated the expression of LPS-induced iNOS and COX-2, which suggests that morin-mediated NF-κB inhibition is the main signaling pathway responsible for the inhibition of iNOS and COX-2 expression. Additionally, morin increased induction of heme oxygenase-1 (HO-1) activity, leading to the suppression of NO and PGE2 production. Our results indicate that morin downregulates the expression of proinflammatory genes, such as iNOS and COX-2, involved in the synthesis of NO and PGE2 in LPS-stimulated BV2 microglial cells by suppressing NF-κB activity and activation of HO-1. Taken together, the findings of the present study suggest that morin may have potential as a therapeutic for the prevention of neuroinflammation. PMID:27131287

  7. Microglial polarization and plasticity: evidence from organotypic hippocampal slice cultures.

    PubMed

    Ajmone-Cat, Maria Antonietta; Mancini, Melissa; De Simone, Roberta; Cilli, Piera; Minghetti, Luisa

    2013-10-01

    Increasing evidence indicates that "functional plasticity" is not solely a neuronal attribute but a hallmark of microglial cells, the main brain resident macrophage population. Far from being a univocal phenomenon, microglial activation can originate a plethora of functional phenotypes, encompassing the classic M1 proinflammatory and the alternative M2 anti-inflammatory phenotypes. This concept overturns the popular view of microglial activation as a synonym of neurotoxicity and neurogenesis failure in brain disorders. The characterization of the alternative programs is a matter of intense investigation, but still scarce information is available on the course of microglial activation, on the reversibility of the different commitments and on the capability of preserving molecular memory of previous priming stimuli. By using organotypic hippocampal slice cultures as a model, we developed paradigms of stimulation aimed at shedding light on some of these aspects. We show that persistent stimulation of TLR4 signaling promotes an anti-inflammatory response and microglial polarization toward M2-like phenotype. Moreover, acute and chronic preconditioning regimens permanently affect the capability to respond to a later challenge, suggesting the onset of mechanisms of molecular memory. Similar phenomena could occur in the intact brain and differently affect the vulnerability of mature and newborn neurons to noxious signals. PMID:23918452

  8. Prostaglandin signaling suppresses beneficial microglial function in Alzheimer's disease models.

    PubMed

    Johansson, Jenny U; Woodling, Nathaniel S; Wang, Qian; Panchal, Maharshi; Liang, Xibin; Trueba-Saiz, Angel; Brown, Holden D; Mhatre, Siddhita D; Loui, Taylor; Andreasson, Katrin I

    2015-01-01

    Microglia, the innate immune cells of the CNS, perform critical inflammatory and noninflammatory functions that maintain normal neural function. For example, microglia clear misfolded proteins, elaborate trophic factors, and regulate and terminate toxic inflammation. In Alzheimer's disease (AD), however, beneficial microglial functions become impaired, accelerating synaptic and neuronal loss. Better understanding of the molecular mechanisms that contribute to microglial dysfunction is an important objective for identifying potential strategies to delay progression to AD. The inflammatory cyclooxygenase/prostaglandin E2 (COX/PGE2) pathway has been implicated in preclinical AD development, both in human epidemiology studies and in transgenic rodent models of AD. Here, we evaluated murine models that recapitulate microglial responses to Aβ peptides and determined that microglia-specific deletion of the gene encoding the PGE2 receptor EP2 restores microglial chemotaxis and Aβ clearance, suppresses toxic inflammation, increases cytoprotective insulin-like growth factor 1 (IGF1) signaling, and prevents synaptic injury and memory deficits. Our findings indicate that EP2 signaling suppresses beneficial microglia functions that falter during AD development and suggest that inhibition of the COX/PGE2/EP2 immune pathway has potential as a strategy to restore healthy microglial function and prevent progression to AD. PMID:25485684

  9. Manganese modulation of MAPK pathways: effects on upstream mitogen activated protein kinase kinases (MKKs) and mitogen activated kinase phosphatase-1 (MKP-1) in microglial cells

    PubMed Central

    Crittenden, Patrick L.; Filipov, Nikolay M.

    2010-01-01

    Multiple studies demonstrate that manganese (Mn) exposure potentiates inflammatory mediator output from activated glia; this increased output is associated with enhanced mitogen activated protein kinase (MAPK: p38, ERK, and JNK) activity. We hypothesized that Mn activates MAPK by activating the kinases upstream of MAPK, i.e., MKK-3/6, MKK-1/2, and MKK-4 (responsible for activation of p38, ERK, and JNK, respectively), and/or by inhibiting a major phosphatase responsible for MAPK inactivation, MKP-1. Exposure of N9 microglia to Mn (250μM), LPS (100 ng/ml), or Mn+LPS increased MKK-3/6 and MKK-4 activity at 1 h; the effect of Mn+LPS on MKK-4 activation was greater than the rest. At 4 h, Mn, LPS, and Mn+LPS increased MKK-3/6 and MKK-1/2 phosphorylation, whereas MKK-4 was activated only by Mn and Mn+LPS. Besides activating MKK-4 via Ser257/Thr261 phosphorylation, Mn (4 h) prevented MKK-4’s phosphorylation on Ser80, which negatively regulates MKK-4 activity. Exposure to Mn or Mn+LPS (1 h) decreased both mRNA and protein expression of MKP-1, the negative MAPK regulator. In addition, we observed that at 4 h, but not at 1 h, a time point coinciding with increased MAPK activity, Mn+LPS markedly increased TNF-α , IL-6, and Cox-2 mRNA, suggesting a delayed effect. The fact that all three major groups of MKKs, MKK-1/2, MKK-3/6, and MKK-4 are activated by Mn suggests that Mn-induced activation of MAPK occurs via traditional mechanisms, which perhaps involve the MAPKs farthest upstream, MKKKs (MAP3Ks). In addition, for all MKKs, Mn-induced activation was persistent at least for 4 h, indicating a long-term effect. PMID:20589745

  10. Modulation of microglial immune responses by a novel thiourea derivative.

    PubMed

    Chern, Jyh-Haur; Hsu, Pei-Chien; Wang, Li-Wen; Tsay, Huey-Jen; Kang, Iou-Jiun; Shie, Feng-Shiun

    2010-10-01

    Increasing evidence indicates that microglial activation plays an important role in the pathogenesis of Alzheimer's disease (AD). In AD, activated microglia may facilitate the clearance of beta-amyloid (Abeta), a neurotoxic component in AD pathogenesis. However, microglial activation comes at the cost of triggering neuro-inflammation, which contributes to cerebral dysfunction. Thus, pharmacological approaches that can achieve a favorable combination of a reduced microglia-mediated neuro-inflammation, and an enhanced Abeta clearance may be beneficial for preventing the progression of the disease. Here, we show that some newly synthesized compounds may exert such a combination of functions. Using mouse primary microglia and RAW264.7 cells, we found that some thiourea derivatives significantly enhanced microglial Abeta phagocytosis and suppressed microglial immune responses, as evidenced by the reduced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2). Of note, some commercially available inhibitors for iNOS and/or COX-2, such as ibuprofen, dextromethorphan, and N(G)-methyl-l-arginine (l-NMA), show negligible effects on microglial Abeta phagocytosis. Among the thiourea derivatives, our data show that a lead compound, designated as compound #326, (1-Naphthalen-1-yl-3-[5-(3-thioureido-phenoxy)-pentyl]-thiourea) appears to be the most potent in promoting Abeta phagocytosis and in inhibiting the LPS-induced expression of iNOS and COX-2 (when used at concentrations in the low muM range). The potency of compound #326 may have beneficial effects on modulating microglial activation in AD. The structure-activity relationship indicates that the thiourea group, alkyl linker, and the hydrophobic aryl group largely influence the dual functions of the compounds. These findings may indicate a structural basis for the improved design of future drug therapies for AD. PMID:20637185

  11. Focal Thalamic Degeneration from Ethanol and Thiamine Deficiency is Associated with Neuroimmune Gene Induction, Microglial Activation, and Lack of Monocarboxylic Acid Transporters

    PubMed Central

    Qin, Liya; Crews, Fulton T

    2014-01-01

    Background Wernicke's encephalopathy-Korsakoff syndrome (WE-KS) is common in alcoholics, caused by thiamine deficiency (TD; vitamin B1) and associated with lesions to the thalamus (THAL). Although TD alone can cause WE, the high incidence in alcoholism suggests that TD and ethanol (EtOH) interact. Methods Mice in control, TD, or EtOH groups alone or combined were studied after 5 or 10 days of treatment. THAL and entorhinal cortex (ENT) histochemistry and mRNA were assessed. Results Combined EtOH-TD treatment for 5 days (EtOH-TD5) showed activated microglia, proinflammatory gene induction and THAL neurodegeneration that was greater than that found with TD alone (TD5), whereas 10 days resulted in marked THAL degeneration and microglial-neuroimmune activation in both groups. In contrast, 10 days of TD did not cause ENT degeneration. Interestingly, in ENT, TD10 activated microglia and astrocytes more than EtOH-TD10. In THAL, multiple astrocytic markers were lost consistent with glial cell loss. TD blocks glucose metabolism more than acetate. Acetate derived from hepatic EtOH metabolism is transported by monocarboxylic acid transporters (MCT) into both neurons and astrocytes that use acetyl-CoA synthetase (AcCoAS) to generate cellular energy from acetate. MCT and AcCoAS expression in THAL is lower than ENT prompting the hypothesis that focal THAL degeneration is related to insufficient MCT and AcCoAS in THAL. To test this hypothesis, we administered glycerin triacetate (GTA) to increase blood acetate and found it protected the THAL from TD-induced degeneration. Conclusions Our findings suggest that EtOH potentiates TD-induced THAL degeneration through neuroimmune gene induction. The findings support the hypothesis that TD deficiency inhibits global glucose metabolism and that a reduced ability to process acetate for cellular energy results in THAL focal degeneration in alcoholics contributing to the high incidence of Wernicke-Korsakoff syndrome in alcoholism. PMID

  12. Resolvins AT-D1 and E1 differentially impact functional outcome, post-traumatic sleep, and microglial activation following diffuse brain injury in the mouse

    PubMed Central

    Harrison, Jordan L.; Rowe, Rachel K.; Ellis, Timothy W.; Yee, Nicole S.; O’Hara, Bruce F.; Adelson, P. David; Lifshitz, Jonathan

    2015-01-01

    Traumatic brain injury (TBI) is induced by mechanical forces which initiate a cascade of secondary injury processes, including inflammation. Therapies which resolve the inflammatory response may promote neural repair without exacerbating the primary injury. Specific derivatives of omega-3 fatty acids loosely grouped as specialized pro-resolving lipid mediators (SPMs) and termed resolvins promote the active resolution of inflammation. In the current study, we investigate the effect of two resolvin molecules, RvE1 and AT-RvD1, on post-traumatic sleep and functional outcome following diffuse TBI through modulation of the inflammatory response. Adult, male C57BL/6 mice were injured using a midline fluid percussion injury (mFPI) model (6-10 min righting reflex time for brain-injured mice). Experimental groups included mFPI administered RvE1 (100ng daily), AT-RvD1 (100ng daily), or vehicle (sterile saline) and counterbalanced with uninjured sham mice. Resolvins or saline were administered daily for seven consecutive days beginning 3 days prior to TBI to evaluate proof-of-principle to improve outcome. Immediately following diffuse TBI, post-traumatic sleep was recorded for 24 hours post-injury. For days 1-7 post-injury, motor outcome was assessed by Rotarod. Cognitive function was measured at 6 days post-injury using Novel Object Recognition (NOR). At 7 days post-injury, microglial activation was quantified using immunohistochemistry for Iba-1. In the diffuse brain-injured mouse, AT-RvD1 treatment, but not RvE1, mitigated motor and cognitive deficits. RvE1 treatment significantly increased post-traumatic sleep in brain-injured mice compared to all other groups. RvE1 treated mice displayed a higher proportion of ramified microglia and lower proportion of activated rod microglia in the cortex compared to saline or AT-RvD1 treated brain-injured mice. Thus, RvE1 treatment modulated post-traumatic sleep and the inflammatory response to TBI, albeit independently of improvement

  13. Resolvins AT-D1 and E1 differentially impact functional outcome, post-traumatic sleep, and microglial activation following diffuse brain injury in the mouse.

    PubMed

    Harrison, Jordan L; Rowe, Rachel K; Ellis, Timothy W; Yee, Nicole S; O'Hara, Bruce F; Adelson, P David; Lifshitz, Jonathan

    2015-07-01

    Traumatic brain injury (TBI) is induced by mechanical forces which initiate a cascade of secondary injury processes, including inflammation. Therapies which resolve the inflammatory response may promote neural repair without exacerbating the primary injury. Specific derivatives of omega-3 fatty acids loosely grouped as specialized pro-resolving lipid mediators (SPMs) and termed resolvins promote the active resolution of inflammation. In the current study, we investigate the effect of two resolvin molecules, RvE1 and AT-RvD1, on post-traumatic sleep and functional outcome following diffuse TBI through modulation of the inflammatory response. Adult, male C57BL/6 mice were injured using a midline fluid percussion injury (mFPI) model (6-10min righting reflex time for brain-injured mice). Experimental groups included mFPI administered RvE1 (100ng daily), AT-RvD1 (100ng daily), or vehicle (sterile saline) and counterbalanced with uninjured sham mice. Resolvins or saline were administered daily for seven consecutive days beginning 3days prior to TBI to evaluate proof-of-principle to improve outcome. Immediately following diffuse TBI, post-traumatic sleep was recorded for 24h post-injury. For days 1-7 post-injury, motor outcome was assessed by rotarod. Cognitive function was measured at 6days post-injury using novel object recognition (NOR). At 7days post-injury, microglial activation was quantified using immunohistochemistry for Iba-1. In the diffuse brain-injured mouse, AT-RvD1 treatment, but not RvE1, mitigated motor and cognitive deficits. RvE1 treatment significantly increased post-traumatic sleep in brain-injured mice compared to all other groups. RvE1 treated mice displayed a higher proportion of ramified microglia and lower proportion of activated rod microglia in the cortex compared to saline or AT-RvD1 treated brain-injured mice. Thus, RvE1 treatment modulated post-traumatic sleep and the inflammatory response to TBI, albeit independently of improvement in motor

  14. Developmental changes in microglial mobilization are independent of apoptosis in the neonatal mouse hippocampus.

    PubMed

    Eyo, Ukpong B; Miner, Samuel A; Weiner, Joshua A; Dailey, Michael E

    2016-07-01

    During CNS development, microglia transform from highly mobile amoeboid-like cells to primitive ramified forms and, finally, to highly branched but relatively stationary cells in maturity. The factors that control developmental changes in microglia are largely unknown. Because microglia detect and clear apoptotic cells, developmental changes in microglia may be controlled by neuronal apoptosis. Here, we assessed the extent to which microglial cell density, morphology, motility, and migration are regulated by developmental apoptosis, focusing on the first postnatal week in the mouse hippocampus when the density of apoptotic bodies peaks at postnatal day 4 and declines sharply thereafter. Analysis of microglial form and distribution in situ over the first postnatal week showed that, although there was little change in the number of primary microglial branches, microglial cell density increased significantly, and microglia were often seen near or engulfing apoptotic bodies. Time-lapse imaging in hippocampal slices harvested at different times over the first postnatal week showed differences in microglial motility and migration that correlated with the density of apoptotic bodies. The extent to which these changes in microglia are driven by developmental neuronal apoptosis was assessed in tissues from BAX null mice lacking apoptosis. We found that apoptosis can lead to local microglial accumulation near apoptotic neurons in the pyramidal cell body layer but, unexpectedly, loss of apoptosis did not alter overall microglial cell density in vivo or microglial motility and migration in ex vivo tissue slices. These results demonstrate that developmental changes in microglial form, distribution, motility, and migration occur essentially normally in the absence of developmental apoptosis, indicating that factors other than neuronal apoptosis regulate these features of microglial development. PMID:26576723

  15. Quantitating the subtleties of microglial morphology with fractal analysis

    PubMed Central

    Karperien, Audrey; Ahammer, Helmut; Jelinek, Herbert F.

    2013-01-01

    It is well established that microglial form and function are inextricably linked. In recent years, the traditional view that microglial form ranges between “ramified resting” and “activated amoeboid” has been emphasized through advancing imaging techniques that point to microglial form being highly dynamic even within the currently accepted morphological categories. Moreover, microglia adopt meaningful intermediate forms between categories, with considerable crossover in function and varying morphologies as they cycle, migrate, wave, phagocytose, and extend and retract fine and gross processes. From a quantitative perspective, it is problematic to measure such variability using traditional methods, but one way of quantitating such detail is through fractal analysis. The techniques of fractal analysis have been used for quantitating microglial morphology, to categorize gross differences but also to differentiate subtle differences (e.g., amongst ramified cells). Multifractal analysis in particular is one technique of fractal analysis that may be useful for identifying intermediate forms. Here we review current trends and methods of fractal analysis, focusing on box counting analysis, including lacunarity and multifractal analysis, as applied to microglial morphology. PMID:23386810

  16. Novel neuroprotective mechanisms of memantine: increase in neurotrophic factor release from astroglia and anti-inflammation by preventing microglial activation.

    PubMed

    Wu, Hung-Ming; Tzeng, Nian-Sheng; Qian, Li; Wei, Sung-Jen; Hu, Xiaoming; Chen, Shih-Heng; Rawls, Scott M; Flood, Patrick; Hong, Jau-Shyong; Lu, Ru-Band

    2009-09-01

    Memantine shows clinically relevant efficacy in patients with Alzheimer's disease and Parkinson's disease. Most in vivo and in vitro studies attribute the neuroprotective effects of memantine to the blockade of N-methyl-D-aspartate (NMDA) receptor on neurons. However, it cannot be excluded that mechanisms other than NMDA receptor blockade may contribute to the neuroprotective effects of this compound. To address this question, primary midbrain neuron-glia cultures and reconstituted cultures were used, and lipopolysaccharide (LPS), an endotoxin from bacteria, was used to produce inflammation-mediated dopaminergic (DA) neuronal death. Here, we show that memantine exerted both potent neurotrophic and neuroprotective effects on DA neurons in rat neuron-glia cultures. The neurotrophic effect of memantine was glia dependent, as memantine failed to show any positive effect on DA neurons in neuron-enriched cultures. More specifically, it seems to be that astroglia, not microglia, are the source of the memantine-elicited neurotrophic effects through the increased production of glial cell line-derived neurotrophic factor (GDNF). Mechanistic studies showed that GDNF upregulation was associated with histone hyperacetylation by inhibiting the cellular histone deacetylase activity. In addition, memantine also displays neuroprotective effects against LPS-induced DA neuronal damage through its inhibition of microglia activation showed by both OX-42 immunostaining and reduction of pro-inflammatory factor production, such as extracellular superoxide anion, intracellular reactive oxygen species, nitric oxide, prostaglandin E(2), and tumor necrosis factor-alpha. These results suggest that the neuroprotective effects of memantine shown in our cell culture studies are mediated in part through alternative novel mechanisms by reducing microglia-associated inflammation and by stimulating neurotrophic factor release from astroglia. PMID:19536110

  17. Microglial action in glioma: a boon turns bane.

    PubMed

    Ghosh, Anirban; Chaudhuri, Swapna

    2010-06-15

    Microglia has the potential to shape the neuroimmune defense with vast array of functional attributes. The cells prime infiltrated lymphocytes to retain their effector functions, play crucial role in controlling microenvironmental milieu and significantly participate in glioma. Reports demonstrate microglial accumulation in glioma and predict their assistance in glioma growth and spreading. Clarification of the 'double-edged' appearance of microglia is necessary to unfold its role in glioma biology. In this article the interpretation of microglial activities has been attempted to reveal their actual function in glioma. Contrary to the trendy acceptance of its glioma promoting infamy, accumulated evidences make an effort to view the state of affairs in favor of the cell. Critical scrutiny indicates that microglial immune assaults are intended to demolish the neoplastic cells in brain. But the weaponry of microglia has been tactically utilized by glioma in their favor as the survival strategy. Hence the defender appears as enemy in advanced glioma. PMID:20338195

  18. Dual RNA Sequencing Reveals the Expression of Unique Transcriptomic Signatures in Lipopolysaccharide-Induced BV-2 Microglial Cells

    PubMed Central

    Kim, Sun Hwa; Park, Kyoung Sun; Lee, Young Seek; Jung, Kyoung Hwa; Chai, Young Gyu

    2015-01-01

    Microglial cells become rapidly activated through interactions with pathogens, and the persistent activation of these cells is associated with various neurodegenerative diseases. Previous studies have investigated the transcriptomic signatures in microglia or macrophages using microarray technologies. However, this method has numerous restrictions, such as spatial biases, uneven probe properties, low sensitivity, and dependency on the probes spotted. To overcome this limitation and identify novel transcribed genes in response to LPS, we used RNA Sequencing (RNA-Seq) to determine the novel transcriptomic signatures in BV-2 microglial cells. Sequencing assessment and quality evaluation showed that approximately 263 and 319 genes (≥ 1.5 log2-fold), such as cytokines and chemokines, were strongly induced after 2 and 4 h, respectively, and the induction of several genes with unknown immunological functions was also observed. Importantly, we observed that previously unidentified transcription factors (TFs) (irf1, irf7, and irf9), histone demethylases (kdm4a) and DNA methyltransferases (dnmt3l) were significantly and selectively expressed in BV-2 microglial cells. The gene expression levels, transcription start sites (TSS), isoforms, and differential promoter usage revealed a complex pattern of transcriptional and post-transcriptional gene regulation upon infection with LPS. In addition, gene ontology, molecular networks and pathway analyses identified the top significantly regulated functional classification, canonical pathways and network functions at each activation status. Moreover, we further analyzed differentially expressed genes to identify transcription factor (TF) motifs (−950 to +50 bp of the 5’ upstream promoters) and epigenetic mechanisms. Furthermore, we confirmed that the expressions of key inflammatory genes as well as pro-inflammatory mediators in the supernatants were significantly induced in LPS treated primary microglial cells. This

  19. Neuroprotection and Functional Recovery Associated with Decreased Microglial Activation Following Selective Activation of mGluR2/3 Receptors in a Rodent Model of Parkinson's Disease

    PubMed Central

    Chan, Hugh; Paur, Helen; Vernon, Anthony C.; Zabarsky, Virginia; Datla, Krishna P.; Croucher, Martin J.; Dexter, David T.

    2010-01-01

    Clinical trials have demonstrated positive proof of efficacy of dual metabotropic glutamate receptor 2/3 (mGluR2/3) agonists in both anxiety and schizophrenia. Importantly, evidence suggests that these drugs may also be neuroprotective against glutamate excitotoxicity, implicated in the pathogenesis of Parkinson's disease (PD). However, whether this neuroprotection also translates into functional recovery is unclear. In the current study, we examined the neuroprotective efficacy of the dual mGluR2/3 agonist, 2R,4R-4-aminopyrrolidine-2,4-dicarboxylate (2R,4R-APDC), and whether this is accompanied by behavioral recovery in a rodent 6-hydroxydopamine (6-OHDA) model of PD. We now report that delayed post lesion treatment with 2R,4R-APDC (10 nmol), results in robust neuroprotection of the nigrostriatal system, which translated into functional recovery as measured by improved forelimb use asymmetry and reduced (+)-amphetamine-induced rotation compared to vehicle treated animals. Interestingly, these beneficial effects were associated with a decrease in microglial markers in the SNc, which may suggest an antiinflammatory action of this drug. PMID:20948891

  20. [The immunomodulatory role of retinal microglial cells in age-related macular degeneration].

    PubMed

    Zhang, P F; Sun, X D

    2016-05-11

    Age-related macular degeneration (AMD) is one of the major causes of visual impairment in the elder population. Recent studies have revealed that retinal microgliacytes may play an important role in the pathogenesis of AMD, and the activation of retinal microglia could regulate the progress of AMD. The immunomodulatory role of retinal microglial cells is reviewed in this article, so as to investigate the mechanism and provide new insight for prevention and treatment of AMD.(Chin J Ophthalmol, 2016, 52: 386-390). PMID:27220713

  1. Gypenoside Attenuates β Amyloid-Induced Inflammation in N9 Microglial Cells via SOCS1 Signaling

    PubMed Central

    Cai, Hui; Liang, Qianlei; Ge, Guanqun

    2016-01-01

    Reducing β amyloid- (Aβ-) induced microglial activation is believed to be effective in treating Alzheimer's disease (AD). Microglia can be activated into classic activated state (M1 state) or alternative activated state (M2 state), and the former is harmful; in contrast, the latter is beneficial. Gypenoside (GP) is the major bioactive constituent of Gynostemma pentaphyllum, a traditional Chinese herb medicine. In this study, we hypothesized that GP attenuates Aβ-induced microglial activation by ameliorating microglial M1/M2 states, and the process may be mediated by suppressor of cell signaling protein 1 (SOCS1). In this study, we found that Aβ exposure increased the levels of microglial M1 markers, including iNOS expression, tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and IL-6 releases, and coadministration of GP reversed the increase of M1 markers and enhanced the levels of M2 markers, including arginase-1 (Arg-1) expression, IL-10, brain-derived neurotrophic factor (BDNF), and glial cell-derived neurotrophic factor (GDNF) releases in the Aβ-treated microglial cells. SOCS1-siRNA, however, significantly abolished the GP-induced effects on the levels of microglial M1 and M2 markers. These findings indicated that GP attenuates Aβ-induced microglial activation by ameliorating M1/M2 states, and the process may be mediated by SOCS1. PMID:27213058

  2. Gypenoside Attenuates β Amyloid-Induced Inflammation in N9 Microglial Cells via SOCS1 Signaling.

    PubMed

    Cai, Hui; Liang, Qianlei; Ge, Guanqun

    2016-01-01

    Reducing β amyloid- (Aβ-) induced microglial activation is believed to be effective in treating Alzheimer's disease (AD). Microglia can be activated into classic activated state (M1 state) or alternative activated state (M2 state), and the former is harmful; in contrast, the latter is beneficial. Gypenoside (GP) is the major bioactive constituent of Gynostemma pentaphyllum, a traditional Chinese herb medicine. In this study, we hypothesized that GP attenuates Aβ-induced microglial activation by ameliorating microglial M1/M2 states, and the process may be mediated by suppressor of cell signaling protein 1 (SOCS1). In this study, we found that Aβ exposure increased the levels of microglial M1 markers, including iNOS expression, tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and IL-6 releases, and coadministration of GP reversed the increase of M1 markers and enhanced the levels of M2 markers, including arginase-1 (Arg-1) expression, IL-10, brain-derived neurotrophic factor (BDNF), and glial cell-derived neurotrophic factor (GDNF) releases in the Aβ-treated microglial cells. SOCS1-siRNA, however, significantly abolished the GP-induced effects on the levels of microglial M1 and M2 markers. These findings indicated that GP attenuates Aβ-induced microglial activation by ameliorating M1/M2 states, and the process may be mediated by SOCS1. PMID:27213058

  3. Anti-Inflammatory and Cytoprotective Effects of TMC-256C1 from Marine-Derived Fungus Aspergillus sp. SF-6354 via up-Regulation of Heme Oxygenase-1 in Murine Hippocampal and Microglial Cell Lines

    PubMed Central

    Kim, Dong-Cheol; Cho, Kwang-Ho; Ko, Wonmin; Yoon, Chi-Su; Sohn, Jae Hak; Yim, Joung Han; Kim, Youn-Chul; Oh, Hyuncheol

    2016-01-01

    In the course of searching for bioactive secondary metabolites from marine fungi, TMC-256C1 was isolated from an ethyl acetate extract of the marine-derived fungus Aspergillus sp. SF6354. TMC-256C1 displayed anti-neuroinflammatory effect in BV2 microglial cells induced by lipopolysaccharides (LPS) as well as neuroprotective effect against glutamate-stimulated neurotoxicity in mouse hippocampal HT22 cells. TMC-256C1 was shown to develop a cellular resistance to oxidative damage caused by glutamate-induced cytotoxicity and reactive oxygen species (ROS) generation in HT22 cells, and suppress the inflammation process in LPS-stimulated BV2 cells. Furthermore, the neuroprotective and anti-neuroinflammatory activities of TMC-256C1 were associated with upregulated expression of heme oxygenase (HO)-1 and nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2) in HT22 and BV2 cells. We also found that TMC-256C1 activated p38 mitogen-activated protein kinases (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways in HT22 and BV2 cells. These results demonstrated that TMC-256C1 activates HO-1 protein expression, probably by increasing nuclear Nrf2 levels via the activation of the p38 MAPK and PI3K/Akt pathways. PMID:27070586

  4. Anti-Inflammatory and Cytoprotective Effects of TMC-256C1 from Marine-Derived Fungus Aspergillus sp. SF-6354 via up-Regulation of Heme Oxygenase-1 in Murine Hippocampal and Microglial Cell Lines.

    PubMed

    Kim, Dong-Cheol; Cho, Kwang-Ho; Ko, Wonmin; Yoon, Chi-Su; Sohn, Jae Hak; Yim, Joung Han; Kim, Youn-Chul; Oh, Hyuncheol

    2016-01-01

    In the course of searching for bioactive secondary metabolites from marine fungi, TMC-256C1 was isolated from an ethyl acetate extract of the marine-derived fungus Aspergillus sp. SF6354. TMC-256C1 displayed anti-neuroinflammatory effect in BV2 microglial cells induced by lipopolysaccharides (LPS) as well as neuroprotective effect against glutamate-stimulated neurotoxicity in mouse hippocampal HT22 cells. TMC-256C1 was shown to develop a cellular resistance to oxidative damage caused by glutamate-induced cytotoxicity and reactive oxygen species (ROS) generation in HT22 cells, and suppress the inflammation process in LPS-stimulated BV2 cells. Furthermore, the neuroprotective and anti-neuroinflammatory activities of TMC-256C1 were associated with upregulated expression of heme oxygenase (HO)-1 and nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2) in HT22 and BV2 cells. We also found that TMC-256C1 activated p38 mitogen-activated protein kinases (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways in HT22 and BV2 cells. These results demonstrated that TMC-256C1 activates HO-1 protein expression, probably by increasing nuclear Nrf2 levels via the activation of the p38 MAPK and PI3K/Akt pathways. PMID:27070586

  5. Suppressor of Cytokine Signaling-2 (SOCS2) Regulates the Microglial Response and Improves Functional Outcome after Traumatic Brain Injury in Mice

    PubMed Central

    Basrai, Harleen S.; Christie, Kimberly J.; Turbic, Alisa; Bye, Nicole; Turnley, Ann M.

    2016-01-01

    Traumatic brain injury (TBI) is frequently characterized by neuronal, axonal and myelin loss, reactive gliosis and neuroinflammation, often associated with functional deficits. Endogenous repair mechanisms include production of new neurons from precursor cells, but usually the new neurons fail to integrate and survive more than a few weeks. This is in part mediated by the toxic and inflammatory environment present in the injured brain which activates precursor cells to proliferate and differentiate but limits survival of the newborn progeny. Therefore, an understanding of mechanisms that regulate production and survival of newborn neurons and the neuroinflammatory response after brain injury may lead to therapeutic options to improve outcomes. Suppressor of Cytokine Signaling 2 (SOCS2) promotes hippocampal neurogenesis and survival of newborn neurons in the adult brain and regulates anti-inflammatory responses in the periphery, suggesting it may be a useful candidate to improve outcomes of TBI. In this study the functional and cellular responses of SOCS2 over-expressing transgenic (SOCS2Tg) mice were compared to wildtype littermates following mild or moderately severe TBI. Unlike wildtype controls, SOCS2Tg mice showed functional improvement on a ladder test, with a smaller lesion volume at 7d post injury and increased numbers of proliferative CD11b+ microglia/macrophages at 35d post-injury in the mild injury paradigm. At 7d post-moderately severe injury there was an increase in the area covered by cells expressing an anti-inflammatory M2 phenotype marker (CD206+) but no difference in cells with a pro-inflammatory M1 phenotype marker (CD16/32+). No effect of SOCS2 overexpression was observed in production or survival of newborn neurons, even in the presence of the neuroprotective agent erythropoietin (EPO). Therefore, SOCS2 may improve outcome of TBI in mice by regulating aspects of the neuroinflammatory response, promoting a more anti-inflammatory environment

  6. Suppressor of Cytokine Signaling-2 (SOCS2) Regulates the Microglial Response and Improves Functional Outcome after Traumatic Brain Injury in Mice.

    PubMed

    Basrai, Harleen S; Christie, Kimberly J; Turbic, Alisa; Bye, Nicole; Turnley, Ann M

    2016-01-01

    Traumatic brain injury (TBI) is frequently characterized by neuronal, axonal and myelin loss, reactive gliosis and neuroinflammation, often associated with functional deficits. Endogenous repair mechanisms include production of new neurons from precursor cells, but usually the new neurons fail to integrate and survive more than a few weeks. This is in part mediated by the toxic and inflammatory environment present in the injured brain which activates precursor cells to proliferate and differentiate but limits survival of the newborn progeny. Therefore, an understanding of mechanisms that regulate production and survival of newborn neurons and the neuroinflammatory response after brain injury may lead to therapeutic options to improve outcomes. Suppressor of Cytokine Signaling 2 (SOCS2) promotes hippocampal neurogenesis and survival of newborn neurons in the adult brain and regulates anti-inflammatory responses in the periphery, suggesting it may be a useful candidate to improve outcomes of TBI. In this study the functional and cellular responses of SOCS2 over-expressing transgenic (SOCS2Tg) mice were compared to wildtype littermates following mild or moderately severe TBI. Unlike wildtype controls, SOCS2Tg mice showed functional improvement on a ladder test, with a smaller lesion volume at 7d post injury and increased numbers of proliferative CD11b+ microglia/macrophages at 35d post-injury in the mild injury paradigm. At 7d post-moderately severe injury there was an increase in the area covered by cells expressing an anti-inflammatory M2 phenotype marker (CD206+) but no difference in cells with a pro-inflammatory M1 phenotype marker (CD16/32+). No effect of SOCS2 overexpression was observed in production or survival of newborn neurons, even in the presence of the neuroprotective agent erythropoietin (EPO). Therefore, SOCS2 may improve outcome of TBI in mice by regulating aspects of the neuroinflammatory response, promoting a more anti-inflammatory environment

  7. Glioblastoma-derived Macrophage Colony-stimulating Factor (MCSF) Induces Microglial Release of Insulin-like Growth Factor-binding Protein 1 (IGFBP1) to Promote Angiogenesis.

    PubMed

    Nijaguna, Mamatha Bangalore; Patil, Vikas; Urbach, Serge; Shwetha, Shivayogi D; Sravani, Kotha; Hegde, Alangar S; Chandramouli, Bangalore A; Arivazhagan, Arimappamagan; Marin, Philippe; Santosh, Vani; Somasundaram, Kumaravel

    2015-09-18

    Glioblastoma (grade IV glioma/GBM) is the most common primary adult malignant brain tumor with poor prognosis. To characterize molecular determinants of tumor-stroma interaction in GBM, we profiled 48 serum cytokines and identified macrophage colony-stimulating factor (MCSF) as one of the elevated cytokines in sera from GBM patients. Both MCSF transcript and protein were up-regulated in GBM tissue samples through a spleen tyrosine kinase (SYK)-dependent activation of the PI3K-NFκB pathway. Ectopic overexpression and silencing experiments revealed that glioma-secreted MCSF has no role in autocrine functions and M2 polarization of macrophages. In contrast, silencing expression of MCSF in glioma cells prevented tube formation of human umbilical vein endothelial cells elicited by the supernatant from monocytes/microglial cells treated with conditioned medium from glioma cells. Quantitative proteomics based on stable isotope labeling by amino acids in cell culture showed that glioma-derived MCSF induces changes in microglial secretome and identified insulin-like growth factor-binding protein 1 (IGFBP1) as one of the MCSF-regulated proteins secreted by microglia. Silencing IGFBP1 expression in microglial cells or its neutralization by an antibody reduced the ability of supernatants derived from microglial cells treated with glioma cell-conditioned medium to induce angiogenesis. In conclusion, this study shows up-regulation of MCSF in GBM via a SYK-PI3K-NFκB-dependent mechanism and identifies IGFBP1 released by microglial cells as a novel mediator of MCSF-induced angiogenesis, of potential interest for developing targeted therapy to prevent GBM progression. PMID:26245897

  8. SENP1 inhibits the IH-induced apoptosis and nitric oxide production in BV2 microglial cells.

    PubMed

    Liu, Song; Wang, Zhong-hua; Xu, Bo; Chen, Kui; Sun, Jin-yuan; Ren, Lian-ping

    2015-11-27

    To reveal SUMOylation and the roles of Sentrin-specific proteases (SENP)s in microglial cells under Intermittent hypoxia (IH) condition would provide more intensive view of understanding the mechanisms of IH-induced central nervous system (CNS) damage. Hence, in the present study, we detected the expression levels of SENPs in microglial cells under IH and normoxia conditions via RT-PCR assay. We found that SENP1 was significantly down-regulated in cells exposure to IH. Subsequently, the effect of IH for the activation of microglia and the potential roles of SENP1 in the SENP1-overexpressing cell lines were investigated via Western blotting, RT-PCR and Griess assay. The present study demonstrated the apoptosis-inducing and activating role of IH on microglia. In addition, we revealed that the effect of IH on BV-2 including apoptosis, nitric oxide synthase (iNOS) expression and nitric oxide (NO) induction can be attenuated by SENP1 overexpression. The results of the present study are of both theoretical and therapeutic significance to explore the potential roles of SENP1 under IH condition and elucidated the mechanisms underlying microglial survival and activation. PMID:26499079

  9. Tomato lectin histochemistry for microglial visualization.

    PubMed

    Villacampa, Nàdia; Almolda, Beatriz; González, Berta; Castellano, Bernardo

    2013-01-01

    The use of different lectins for the study of microglial cells in the central nervous system (CNS) is a valuable tool that has been extensively used in the last years for the selective staining of this glial cell population, not only in normal physiological conditions, but also in a wide range of pathological situations where the normal homeostasis of the parenchyma is disturbed. In this chapter we accurately describe the methodology for the selective labelling of microglial cells by using the tomato lectin (TL), a protein lectin obtained from Lycopersicum esculentum with specific affinity for poly-N-acetyl lactosamine sugar residues which are found on the plasma membrane and in the cytoplasm of microglia. Here we describe how to perform this technique on vibratome, frozen, and paraffin sections for optical microscopy, as well as for transmission electron microscopy (TEM) studies. Using this methodology it is possible to visualize amoeboid microglia in the developing brain, ramified microglia in the adult, and activated/reactive microglia in the experimentally damaged brain. In addition, as TL also recognized sugar residues in endothelial cells, this technique is very useful for the study of the relationship established between microglia and the CNS vasculature. PMID:23813385

  10. CXCR7 suppression modulates microglial chemotaxis to ameliorate experimentally-induced autoimmune encephalomyelitis.

    PubMed

    Bao, Jianhong; Zhu, Jinying; Luo, Sheng; Cheng, Ying; Zhou, Saijun

    2016-01-01

    Multiple sclerosis (MS) is the prototypical inflammatory demyelinating disease of the central nervous system (CNS). Experimental autoimmune encephalomyelitis (EAE), widely used as an animal model of MS, classically manifests as an ascending paralysis that is characterized by extensive infiltration of the CNS by inflammatory cells. Although several studies uncover the significant role of microglia in the development of EAE, the cellular mechanisms of microglia that govern EAE pathogenesis remain unknown. In the current study, we report that CXCR7 expression is dynamic regulated in activated microglia during CNS autoimmunity and positively correlates with the clinical severity of EAE. In addition, microglial chemotaxis is mediated by CXCR7 during CNS autoimmunity, signaling through extracellular signal-regulated kinase (ERK)1/2 activation, whereas p38 mitogen-activated protein kinase (MAPK) and (c-Jun N-terminal kinase) JNK are not involved. Most importantly, CXCR7 neutralizing treatment ameliorates the clinical severity of EAE along with ERK1/2 phosphorylation reduction. Collectively, our data demonstrate that CXCR7 suppression modulates microglial chemotaxis to ameliorate EAE. PMID:26607112