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Endothelial Protein C Receptor Expression is Regulated by Sp1 Transcription Factor in Murine Microglia. JOURNAL OF BASIC AND CLINICAL HEALTH SCIENCES 2021. [DOI: 10.30621/jbachs.854244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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2
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Emerging Roles of Protease-Activated Receptors (PARs) in the Modulation of Synaptic Transmission and Plasticity. Int J Mol Sci 2021; 22:ijms22020869. [PMID: 33467143 PMCID: PMC7830300 DOI: 10.3390/ijms22020869] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 01/13/2021] [Accepted: 01/14/2021] [Indexed: 12/22/2022] Open
Abstract
Protease-activated receptors (PARs) are a class of G protein-coupled receptors (GPCRs) with a unique mechanism of activation, prompted by a proteolytic cleavage in their N-terminal domain that uncovers a tethered ligand, which binds and stimulates the same receptor. PARs subtypes (PAR1-4) have well-documented roles in coagulation, hemostasis, and inflammation, and have been deeply investigated for their function in cellular survival/degeneration, while their roles in the brain in physiological conditions remain less appreciated. Here, we describe PARs’ effects in the modulation of neurotransmission and synaptic plasticity. Available evidence, mainly concerning PAR1-mediated and PAR2-mediated regulation of glutamatergic and GABAergic transmission, supports that PARs are important modulators of synaptic efficacy and plasticity in normal conditions.
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Role of the protease-activated receptor 1 in regulating the function of glial cells within central and peripheral nervous system. J Neural Transm (Vienna) 2019; 126:1259-1271. [DOI: 10.1007/s00702-019-02075-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 08/31/2019] [Indexed: 02/07/2023]
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Podocalyxin is required for maintaining blood-brain barrier function during acute inflammation. Proc Natl Acad Sci U S A 2019; 116:4518-4527. [PMID: 30787191 DOI: 10.1073/pnas.1814766116] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Podocalyxin (Podxl) is broadly expressed on the luminal face of most blood vessels in adult vertebrates, yet its function on these cells is poorly defined. In the present study, we identified specific functions for Podxl in maintaining endothelial barrier function. Using electrical cell substrate impedance sensing and live imaging, we found that, in the absence of Podxl, human umbilical vein endothelial cells fail to form an efficient barrier when plated on several extracellular matrix substrates. In addition, these monolayers lack adherens junctions and focal adhesions and display a disorganized cortical actin cytoskeleton. Thus, Podxl has a key role in promoting the appropriate endothelial morphogenesis required to form functional barriers. This conclusion is further supported by analyses of mutant mice in which we conditionally deleted a floxed allele of Podxl in vascular endothelial cells (vECs) using Tie2Cre mice (Podxl ΔTie2Cre). Although we did not detect substantially altered permeability in naïve mice, systemic priming with lipopolysaccharide (LPS) selectively disrupted the blood-brain barrier (BBB) in Podxl ΔTie2Cre mice. To study the potential consequence of this BBB breach, we used a selective agonist (TFLLR-NH2) of the protease-activated receptor-1 (PAR-1), a thrombin receptor expressed by vECs, neuronal cells, and glial cells. In response to systemic administration of TFLLR-NH2, LPS-primed Podxl ΔTie2Cre mice become completely immobilized for a 5-min period, coinciding with severely dampened neuroelectric activity. We conclude that Podxl expression by CNS tissue vECs is essential for BBB maintenance under inflammatory conditions.
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Younger D, Murugan M, Rama Rao KV, Wu LJ, Chandra N. Microglia Receptors in Animal Models of Traumatic Brain Injury. Mol Neurobiol 2018; 56:5202-5228. [DOI: 10.1007/s12035-018-1428-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 11/13/2018] [Indexed: 02/07/2023]
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Pompili E, Fabrizi C, Somma F, Correani V, Maras B, Schininà ME, Ciraci V, Artico M, Fornai F, Fumagalli L. PAR1 activation affects the neurotrophic properties of Schwann cells. Mol Cell Neurosci 2017; 79:23-33. [PMID: 28064059 DOI: 10.1016/j.mcn.2017.01.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 12/14/2016] [Accepted: 01/01/2017] [Indexed: 01/02/2023] Open
Abstract
Protease-activated receptor-1 (PAR1) is the prototypic member of a family of four G-protein-coupled receptors that signal in response to extracellular proteases. In the peripheral nervous system, the expression and/or the role of PARs are still poorly investigated. High PAR1 mRNA expression was found in the rat dorsal root ganglia and the signal intensity of PAR1 mRNA increased in response to sciatic nerve transection. In the sciatic nerve, functional PAR1 receptor was reported at the level of non-compacted Schwann cell myelin microvilli of the nodes of Ranvier. Schwann cells are the principal population of glial cells of the peripheral nervous system which myelinate axons playing an important role during axonal regeneration and remyelination. The present study was undertaken in order to determine if the activation of PAR1 affects the neurotrophic properties of Schwann cells. Our results suggest that the stimulation of PAR1 could potentiate the Schwann cell ability to favour nerve regeneration. In fact, the conditioned medium obtained from Schwann cell cultures challenged with a specific PAR1 activating peptide (PAR1 AP) displays increased neuroprotective and neurotrophic properties with respect to the culture medium from untreated Schwann cells. The proteomic analysis of secreted proteins in untreated and PAR1 AP-treated Schwann cells allowed the identification of factors differentially expressed in the two samples. Some of them (such as macrophage migration inhibitory factor, matrix metalloproteinase-2, decorin, syndecan 4, complement C1r subcomponent, angiogenic factor with G patch and FHA domains 1) appear to be transcriptionally regulated after PAR1 AP treatment as shown by RT-PCR.
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Affiliation(s)
- Elena Pompili
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University of Rome, Rome, Italy.
| | - Cinzia Fabrizi
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University of Rome, Rome, Italy
| | - Francesca Somma
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University of Rome, Rome, Italy
| | - Virginia Correani
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy
| | - Bruno Maras
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy
| | | | - Viviana Ciraci
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University of Rome, Rome, Italy
| | - Marco Artico
- Department of Sensory Organs, Sapienza University of Rome, Rome, Italy
| | - Francesco Fornai
- Department of Human Morphology and Applied Biology, University of Pisa, Pisa, Italy; IRCCS Neuromed, Pozzilli, Italy
| | - Lorenzo Fumagalli
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Sapienza University of Rome, Rome, Italy
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Morihara R, Yamashita T, Kono S, Shang J, Nakano Y, Sato K, Hishikawa N, Ohta Y, Heitmeier S, Perzborn E, Abe K. Reduction of intracerebral hemorrhage by rivaroxaban after tPA thrombolysis is associated with downregulation of PAR-1 and PAR-2. J Neurosci Res 2016; 95:1818-1828. [PMID: 28035779 DOI: 10.1002/jnr.24013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 11/18/2016] [Accepted: 12/12/2016] [Indexed: 12/20/2022]
Abstract
This study aimed to assess the risk of intracerebral hemorrhage (ICH) after tissue-type plasminogen activator (tPA) treatment in rivaroxaban compared with warfarin-pretreated male Wistar rat brain after ischemia in relation to activation profiles of protease-activated receptor-1, -2, -3, and -4 (PAR-1, -2, -3, and -4). After pretreatment with warfarin (0.2 mg/kg/day), low-dose rivaroxaban (60 mg/kg/day), high-dose rivaroxaban (120 mg/kg/day), or vehicle for 14 days, transient middle cerebral artery occlusion was induced for 90 min, followed by reperfusion with tPA (10 mg/kg/10 ml). Infarct volume, hemorrhagic volume, immunoglobulin G leakage, and blood parameters were examined. Twenty-four hours after reperfusion, immunohistochemistry for PARs was performed in brain sections. ICH volume was increased in the warfarin-pretreated group compared with the rivaroxaban-treated group. PAR-1, -2, -3, and -4 were widely expressed in the normal brain, and their levels were increased in the ischemic brain, especially in the peri-ischemic lesion. Warfarin pretreatment enhanced the expression of PAR-1 and PAR-2 in the peri-ischemic lesion, whereas rivaroxaban pretreatment did not. The present study shows a lower risk of brain hemorrhage in rivaroxaban-pretreated compared with warfarin-pretreated rats following tPA administration to the ischemic brain. It is suggested that the relative downregulation of PAR-1 and PAR-2 by rivaroxaban compared with warfarin pretreatment might be partly involved in the mechanism of reduced hemorrhagic complications in patients receiving rivaroxaban in clinical trials. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Ryuta Morihara
- Departments of Neurology, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University, Okayama, Japan
| | - Toru Yamashita
- Departments of Neurology, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University, Okayama, Japan
| | - Syoichiro Kono
- Departments of Neurology, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University, Okayama, Japan
| | - Jingwei Shang
- Departments of Neurology, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University, Okayama, Japan
| | - Yumiko Nakano
- Departments of Neurology, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University, Okayama, Japan
| | - Kota Sato
- Departments of Neurology, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University, Okayama, Japan
| | - Nozomi Hishikawa
- Departments of Neurology, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University, Okayama, Japan
| | - Yasuyuki Ohta
- Departments of Neurology, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University, Okayama, Japan
| | - Stefan Heitmeier
- Bayer Pharma AG, Drug Discovery-Global Therapeutic Research Groups, Cardiovascular Pharmacology, Wuppertal, Germany
| | - Elisabeth Perzborn
- Bayer Pharma AG, Drug Discovery-Global Therapeutic Research Groups, Cardiovascular Pharmacology, Wuppertal, Germany
| | - Koji Abe
- Departments of Neurology, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University, Okayama, Japan
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Peña-Ortega F, Rivera-Angulo AJ, Lorea-Hernández JJ. Pharmacological Tools to Study the Role of Astrocytes in Neural Network Functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 949:47-66. [DOI: 10.1007/978-3-319-40764-7_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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9
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Hanisch UK. Functional diversity of microglia - how heterogeneous are they to begin with? Front Cell Neurosci 2013; 7:65. [PMID: 23717262 PMCID: PMC3653062 DOI: 10.3389/fncel.2013.00065] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 04/19/2013] [Indexed: 02/06/2023] Open
Abstract
Microglia serve in the surveillance and maintenance, protection and restoration of the central nervous system (CNS) homeostasis. By their parenchymal location they differ from other CNS-associated myeloid cells, and by origin as well as functional characteristics they are also–at least in part–distinct from extraneural tissue macrophages. Nevertheless, microglia themselves may not comprise a uniform cell type. CNS regions vary by cellular and chemical composition, including white matter (myelin) content, blood–brain barrier properties or prevailing neurotransmitters. Such a micromilieu could instruct as well as require local adaptions of microglial features. Yet even cells within circumscribed populations may reveal some specialization by subtypes, regarding house-keeping duties and functional capacities upon challenges. While diversity of reactive phenotypes has been established still little is known as to whether all activated cells would respond with the same program of induced genes and functions or whether responder subsets have individual contributions. Preferential synthesis of a key cytokine could asign a master control to certain cells among a pool of activated microglia. Critical functions could be sequestered to discrete microglial subtypes in order to avoid interference, such as clearance of endogenous material and presentation of antigens. Indeed, several and especially a number of recent studies provide evidence for the constitutive and reactive heterogeneity of microglia by and within CNS regions. While such a principle of “division of labor” would influence the basic notion of “the” microglia, it could come with the practival value of addressing separate microglia types in experimental and therapeutic manipulations.
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Abstract
Microglial cells are the resident macrophages in the central nervous system. These cells of mesodermal/mesenchymal origin migrate into all regions of the central nervous system, disseminate through the brain parenchyma, and acquire a specific ramified morphological phenotype termed "resting microglia." Recent studies indicate that even in the normal brain, microglia have highly motile processes by which they scan their territorial domains. By a large number of signaling pathways they can communicate with macroglial cells and neurons and with cells of the immune system. Likewise, microglial cells express receptors classically described for brain-specific communication such as neurotransmitter receptors and those first discovered as immune cell-specific such as for cytokines. Microglial cells are considered the most susceptible sensors of brain pathology. Upon any detection of signs for brain lesions or nervous system dysfunction, microglial cells undergo a complex, multistage activation process that converts them into the "activated microglial cell." This cell form has the capacity to release a large number of substances that can act detrimental or beneficial for the surrounding cells. Activated microglial cells can migrate to the site of injury, proliferate, and phagocytose cells and cellular compartments.
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Almonte AG, Sweatt JD. Serine proteases, serine protease inhibitors, and protease-activated receptors: roles in synaptic function and behavior. Brain Res 2011; 1407:107-22. [PMID: 21782155 DOI: 10.1016/j.brainres.2011.06.042] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Revised: 06/03/2011] [Accepted: 06/16/2011] [Indexed: 12/11/2022]
Abstract
Serine proteases, serine protease inhibitors, and protease-activated receptors have been intensively investigated in the periphery and their roles in a wide range of processes-coagulation, inflammation, and digestion, for example-have been well characterized (see Coughlin, 2000; Macfarlane et al., 2001; Molinari et al., 2003; Wang et al., 2008; Di Cera, 2009 for reviews). A growing number of studies demonstrate that these protein systems are widely expressed in many cell types and regions in mammalian brains. Accumulating lines of evidence suggest that the brain has co-opted the activities of these interesting proteins to regulate various processes underlying synaptic activity and behavior. In this review, we discuss emerging roles for serine proteases in the regulation of mechanisms underlying synaptic plasticity and memory formation.
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Affiliation(s)
- Antoine G Almonte
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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12
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Pompili E, Fabrizi C, Nori SL, Panetta B, Geloso MC, Corvino V, Michetti F, Fumagalli L. Protease-activated receptor-1 expression in rat microglia after trimethyltin treatment. J Histochem Cytochem 2011; 59:302-11. [PMID: 21378284 DOI: 10.1369/0022155410397996] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the nervous system, protease-activated receptors (PARs), which are activated by thrombin and other extracellular proteases, are expressed widely at both neuronal and glial levels and have been shown to be involved in several brain pathologies. As far as the glial receptors are concerned, previous experiments performed in rat hippocampus showed that expression of PAR-1, the prototypic member of the PAR family, increased in astrocytes both in vivo and in vitro following treatment with trimethyltin (TMT). TMT is an organotin compound that induces severe hippocampal neurodegeneration associated with astrocyte and microglia activation. In the present experiments, the authors extended their investigation to microglial cells. In particular, by 7 days following TMT intoxication in vivo, confocal immunofluorescence revealed an evident PAR-1-related specific immunoreactivity in OX-42-positive microglial cells of the CA3 and hilus hippocampal regions. In line with the in vivo results, when primary rat microglial cells were treated in vitro with TMT, a strong upregulation of PAR-1 was observed by immunocytochemistry and Western blot analysis. These data provide further evidence that PAR-1 may be involved in microglial response to brain damage.
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Affiliation(s)
- Elena Pompili
- Department of Human Anatomy, University of Rome "La Sapienza," Rome, Italy
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13
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Acanthamoeba culbertsoni elicits soluble factors that exert anti-microglial cell activity. Infect Immun 2010; 78:4001-11. [PMID: 20605979 DOI: 10.1128/iai.00047-10] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acanthamoeba culbertsoni is an opportunistic pathogen that causes granulomatous amoebic encephalitis (GAE), a chronic and often fatal disease of the central nervous system (CNS). A hallmark of GAE is the formation of granulomas around the amoebae. These cellular aggregates consist of microglia, macrophages, lymphocytes, and neutrophils, which produce a myriad of proinflammatory soluble factors. In the present study, it is demonstrated that A. culbertsoni secretes serine peptidases that degrade chemokines and cytokines produced by a mouse microglial cell line (BV-2 cells). Furthermore, soluble factors present in cocultures of A. culbertsoni and BV-2 cells, as well as in cocultures of A. culbertsoni and primary neonatal rat cerebral cortex microglia, induced apoptosis of these macrophage-like cells. Collectively, the results indicate that A. culbertsoni can apply a multiplicity of cell contact-independent modes to target macrophage-like cells that exert antiamoeba activities in the CNS.
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14
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Guo H, Singh I, Wang Y, Deane R, Barrett T, Fernández JA, Chow N, Griffin JH, Zlokovic BV. Neuroprotective activities of activated protein C mutant with reduced anticoagulant activity. Eur J Neurosci 2009; 29:1119-30. [PMID: 19302148 DOI: 10.1111/j.1460-9568.2009.06664.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The anticoagulant activated protein C (APC) protects neurons and endothelium via protease activated receptor (PAR)1, PAR3 and endothelial protein C receptor. APC is neuroprotective in stroke models. Bleeding complications may limit the pharmacologic utility of APC. Here, we compared the 3K3A-APC mutant with 80% reduced anticoagulant activity and wild-type (wt)-APC. Murine 3K3A-APC compared with wt-APC protected mouse cortical neurons from N-methyl-D-aspartate-induced apoptosis with twofold greater efficacy and more potently reduced N-methyl-D-aspartate excitotoxic lesions in vivo. Human 3K3A-APC protected human brain endothelial cells (BECs) from oxygen/glucose deprivation with 1.7-fold greater efficacy than wt-APC. 3K3A-APC neuronal protection required PAR1 and PAR3, as shown by using PAR-specific blocking antibodies and PAR1- and PAR3-deficient cells and mice. BEC protection required endothelial protein C receptor and PAR1. In neurons and BECs, 3K3A-APC blocked caspase-9 and -3 activation and induction of p53, and decreased the Bax/Bcl-2 pro-apoptotic ratio. After distal middle cerebral artery occlusion (dMCAO) in mice, murine 3K3A-APC compared with vehicle given 4:00 h after dMCAO improved the functional outcome and reduced the infarction volume by 50% within 3 days. 3K3A-APC compared with wt-APC multi-dosing therapy at 12:00 h, 1, 3, 5 and 7 days after dMCAO significantly improved functional recovery and reduced the infarction volume by 75% and 38%, respectively, within 7 days. The wt-APC, but not 3K3A-APC, significantly increased the risk of intracerebral bleeding as indicated by a 50% increase in hemoglobin levels in the ischemic hemisphere. Thus, 3K3A-APC offers a new approach for safer and more efficacious treatments of neurodegenerative disorders and stroke with APC.
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Affiliation(s)
- Huang Guo
- Department for Neurosurgery and Neurology, Center for Neurodegenerative and Vascular Brain Disorders, University of Rochester Medical Center, Rochester, NY 14642, USA
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Yesilirmak DC, Kumral A, Tugyan K, Cilaker S, Baskin H, Yilmaz O, Duman N, Ozkan H. Effects of activated protein C on neonatal hypoxic ischemic brain injury. Brain Res 2008; 1210:56-62. [DOI: 10.1016/j.brainres.2008.02.088] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Revised: 02/22/2008] [Accepted: 02/25/2008] [Indexed: 11/28/2022]
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17
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Weinstein JR, Swarts S, Bishop C, Hanisch UK, Möller T. Lipopolysaccharide is a frequent and significant contaminant in microglia-activating factors. Glia 2008; 56:16-26. [PMID: 17910052 PMCID: PMC2926344 DOI: 10.1002/glia.20585] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Lipopolysaccharide (LPS/endotoxin) is a potent immunologic stimulant. Many commercial-grade reagents used in research are not screened for LPS contamination. LPS induces a wide spectrum of proinflammatory responses in microglia, the immune cells of the brain. Recent studies have demonstrated that a broad range of endogenous factors including plasma-derived proteins and bioactive phospholipids can also activate microglia. However, few of these studies have reported either the LPS levels found in the preparations used or the effect of LPS inhibitors such as polymyxin B (PMX) on factor-induced responses. Here, we used the Limulus amoebocyte lysate assay to screen a broad range of commercial- and pharmaceutical-grade proteins, peptides, lipids, and inhibitors commonly used in microglia research for contamination with LPS. We then characterized the ability of PMX to alter a representative set of factor-induced microglial activation parameters including surface antigen expression, metabolic activity/proliferation, and NO/cytokine/chemokine release in both the N9 microglial cell line and primary microglia. Significant levels of LPS contamination were detected in a number of commercial-grade plasma/serum- and nonplasma/serum-derived proteins, phospholipids, and synthetic peptide preparations, but not in pharmaceutical-grade recombinant proteins or pharmacological inhibitors. PMX had a significant inhibitory effect on the microglia-activating potential of a number of commercial-, but not pharmaceutical-grade, protein preparations. Novel PMX-resistant responses to alpha(2)-macroglobulin and albumin were incidentally observed. Our results indicate that LPS is a frequent and significant contaminant in commercial-grade preparations of previously reported microglia-activating factors. Careful attention to LPS levels and appropriate controls are necessary for future studies in the neuroinflammation field.
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Affiliation(s)
- Jonathan R Weinstein
- Department of Neurology, School of Medicine, University of Washington, Seattle, Washington 98195, USA.
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18
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Yu PJ, Ferrari G, Pirelli L, Galloway AC, Mignatti P, Pintucci G. Thrombin cleaves the high molecular weight forms of basic fibroblast growth factor (FGF-2): a novel mechanism for the control of FGF-2 and thrombin activity. Oncogene 2007; 27:2594-601. [PMID: 17968311 DOI: 10.1038/sj.onc.1210899] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The fgf-2 gene encodes low molecular weight (LMW, 18 kDa) and high molecular weight (HMW, 22-24 kDa) forms that originate from alternative translation of a single mRNA and exhibit diverse biological functions. HMW fibroblast growth factor-2 (FGF-2) inhibits cell migration and induces cell transformation or growth arrest in a cell type- and dose-dependent fashion. Conversely, LMW FGF-2 upregulates both cell proliferation and migration in most cell types. Although transcriptional and translational regulation of HMW and LMW FGF-2 has been extensively investigated, little is known about post-translational control of their relative expression. Here we report that thrombin, a key coagulation factor and inflammatory mediator, cleaves HMW FGF-2 into an LMW FGF-2-like form that stimulates endothelial cell migration and proliferation. The effect of thrombin on these cell functions requires HMW FGF-2 cleavage. This post-translational control mechanism adds a novel level of complexity to the regulation of FGF-2, and links the activities of thrombin and FGF-2 in patho-physiological processes in which both molecules are expressed.
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Affiliation(s)
- P-J Yu
- Department of Cardiothoracic Surgery, The Seymour Cohn Cardiovascular Research Laboratory, New York University School of Medicine, New York, NY 10016, USA
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Luo W, Wang Y, Reiser G. Protease-activated receptors in the brain: receptor expression, activation, and functions in neurodegeneration and neuroprotection. ACTA ACUST UNITED AC 2007; 56:331-45. [PMID: 17915333 DOI: 10.1016/j.brainresrev.2007.08.002] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Revised: 08/15/2007] [Accepted: 08/18/2007] [Indexed: 11/15/2022]
Abstract
Protease-activated receptors (PARs) are G protein-coupled receptors that regulate the cellular response to extracellular serine proteases, like thrombin, trypsin, and tryptase. The PAR family consists of four members: PAR-1, -3, and -4 as thrombin receptors and PAR-2 as the trypsin/tryptase receptor, which are abundantly expressed in the brain throughout development. Recent evidence has supported the direct involvement of PARs in brain development and function. The expression of PARs in the brain is differentially upregulated or downregulated under pathological conditions in neurodegenerative disorders, like Parkinson's disease, Alzheimer's disease, multiple sclerosis, stroke, and human immunodeficiency virus-associated dementia. Activation of PARs mediates cell death or cell survival in the brain, depending on the amplitude and the duration of agonist stimulation. Interference or potentiation of PAR activation is beneficial in animal models of neurodegenerative diseases. Therefore, PARs mediate either neurodegeneration or neuroprotection in neurodegenerative diseases and represent attractive therapeutic targets for treatment of brain injuries. Here, we review the abnormal expression of PARs in the brain under pathological conditions, the functions of PARs in neurodegenerative disorders, and the molecular mechanisms involved.
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Affiliation(s)
- Weibo Luo
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany
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Yesilirmak DC, Kumral A, Baskin H, Ergur BU, Aykan S, Genc S, Genc K, Yilmaz O, Tugyan K, Giray O, Duman N, Ozkan H. Activated protein C reduces endotoxin-induced white matter injury in the developing rat brain. Brain Res 2007; 1164:14-23. [PMID: 17644074 DOI: 10.1016/j.brainres.2007.04.083] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2006] [Revised: 03/26/2007] [Accepted: 04/09/2007] [Indexed: 11/16/2022]
Abstract
Periventricular leukomalacia (PVL), the dominant form of brain injury in premature infants, is characterized by white matter injury (WMI) and is associated with cerebral palsy. The pathogenesis of PVL is complex and likely involves ischemia/reperfusion, free radical formation, excitotoxicity, impaired regulation of cerebral blood flow, a procoagulant state, and inflammatory mechanisms associated with maternal and/or fetal infection. Using an established animal model of human PVL, we investigated whether activated protein C (APC), an anti-coagulant factor with anti-inflammatory, anti-apoptotic, anti-oxidant, and cytoprotective activities, could reduce endotoxin-induced WMI in the developing rat brain. Intraperitoneal injections of lipopolysaccharide (LPS) (0.5 mg/kg body weight) were given at embryonic days 18 (E18) and 19 (E19) to pregnant Sprague-Dawley rats; control rats were injected with sterile saline. A single intravenous injection of recombinant human (rh) APC (0.2 mg /kg body weight) was given to pregnant rats following the second LPS dose on embryonic day 19 (E19). Reduced cell death in white matter and hypomyelination were shown on TUNEL and myelin basic protein (MBP) staining, respectively, on late postnatal days (P7) in APC-treated groups. There were significantly fewer TUNEL+nuclei in the periventricular WM in the APC+LPS group than in the untreated LPS group. Compared to the APC+LPS and control group, MBP expression was weak in the LPS group on P7, indicating endotoxin-induced hypomyelination in the developing rat brain. APC attenuated the LPS-induced protein expression of inflammatory cytokines, tumor necrosis factor-alpha, and interleukin-6, as evaluated by ELISA in neonatal rat brains. A single intraperitoneal injection of rhAPC (0.2 mg/kg body weight) to neonatal rats on P1 also had similar protective and anti-inflammatory effects against maternally administered LPS. Collectively, these data support the hypothesis that APC may provide protection against an endotoxin-evoked inflammatory response and WMI in the developing rat brain. Moreover, our results suggest that the possible use of APC in treatment of preterm infants and pregnant women with maternal or placental infection may minimize the risk of PVL and cerebral palsy.
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MESH Headings
- Animals
- Animals, Newborn
- Anticoagulants/metabolism
- Anticoagulants/pharmacology
- Anticoagulants/therapeutic use
- Apoptosis/drug effects
- Apoptosis/physiology
- Brain/drug effects
- Brain/growth & development
- Brain/physiopathology
- Central Nervous System Bacterial Infections/complications
- Central Nervous System Bacterial Infections/physiopathology
- Cerebral Palsy/etiology
- Cerebral Palsy/physiopathology
- Cerebral Palsy/prevention & control
- Disease Models, Animal
- Encephalitis/complications
- Encephalitis/drug therapy
- Encephalitis/microbiology
- Endotoxins/antagonists & inhibitors
- Endotoxins/toxicity
- Female
- Humans
- Infant, Newborn
- Inflammation Mediators/antagonists & inhibitors
- Inflammation Mediators/metabolism
- Injections, Intravenous
- Leukomalacia, Periventricular/drug therapy
- Leukomalacia, Periventricular/physiopathology
- Leukomalacia, Periventricular/prevention & control
- Lipopolysaccharides/pharmacology
- Myelin Basic Protein/drug effects
- Myelin Basic Protein/metabolism
- Nerve Fibers, Myelinated/drug effects
- Nerve Fibers, Myelinated/immunology
- Nerve Fibers, Myelinated/pathology
- Neuroprotective Agents/metabolism
- Neuroprotective Agents/pharmacology
- Neuroprotective Agents/therapeutic use
- Pregnancy
- Protein C/metabolism
- Protein C/pharmacology
- Protein C/therapeutic use
- Rats
- Rats, Sprague-Dawley
- Recombinant Proteins/pharmacology
- Recombinant Proteins/therapeutic use
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Affiliation(s)
- Didem Cemile Yesilirmak
- Department of Pediatrics, School of Medicine, Dokuz Eylul, University, Inciralti, 35340, Izmir, Turkey
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21
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de Haas AH, Boddeke HWGM, Brouwer N, Biber K. Optimized isolation enables ex vivo analysis of microglia from various central nervous system regions. Glia 2007; 55:1374-84. [PMID: 17661344 DOI: 10.1002/glia.20554] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Ex vivo analysis is an accurate and convenient way to study in vivo microglia phenotype and function. However, current microglia isolation protocols for ex vivo analysis show many differences in isolation steps (perfusion, removal of meninges and blood vessels, mechanical dissociation, enzymatic dissociation, density separation, immunomagnetic separation, and fluorescence-activated cell sorting), often without addressing their effects on microglia purity, number, phenotype, and function. Therefore, the aim of this study was to provide an optimized isolation protocol with emphasis on microglia purity and number to enable ex vivo analysis of adult mouse microglia. The application of this protocol for ex vivo phenotype and functional analysis is corroborated by results from flow cytometry, gene expression analysis, chemotaxis, and phagocytosis assays. In addition, this study shows the possibility to analyze microglia isolated from various central nervous system regions such as optic nerve, striatum, hippocampus, spinal cord, cerebellum, and cerebral cortex. Furthermore, this is the first study presenting DRAQ5 as a superior alternative to propidium iodide for the discrimination between living and dead cells. DRAQ5 staining facilitated the identification of microglia upon flow cytometry without the need of additional fluorescent markers. Along with a favorable emission spectrum, DRAQ5 proved a valuable tool for flow cytometry of microglia. The presented optimized microglia isolation protocol for ex vivo analysis offers the opportunity to obtain more insight into both general and region-specific microglia behavior.
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Affiliation(s)
- Alexander H de Haas
- Department of Medical Physiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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22
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Laskowski A, Reiser G, Reymann KG. Protease-activated receptor-1 induces generation of new microglia in the dentate gyrus of traumatised hippocampal slice cultures. Neurosci Lett 2007; 415:17-21. [PMID: 17324513 DOI: 10.1016/j.neulet.2006.12.050] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2006] [Revised: 11/29/2006] [Accepted: 12/11/2006] [Indexed: 10/23/2022]
Abstract
The protease thrombin is not only known as a major component in the blood coagulation cascade but is also involved in proinflammatory processes in the central nervous system (CNS). Here we used an in vitro model, to investigate the effect of thrombin and protease-activated receptor-1 (PAR-1) on proliferation and microgliosis after traumatic injury. A 5-day exposure to thrombin after cutting the Schaffer collaterals induced a proliferation and microgliosis in the dentate gyrus of organotypic slice cultures. This effect is at least partially mediated by PAR-1 since the selective peptide agonist TRag shows similar effects. Thus, thrombin effects after injury might involve microglial proliferation.
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Affiliation(s)
- Alexandra Laskowski
- Leibniz Institut für Neurobiologie, Brennecke Str. 6, 39118 Magdeburg, Germany
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23
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Genc K. The rationale for activated protein C treatment in perinatal white matter injury. Med Hypotheses 2007; 68:1418-9. [PMID: 17197113 DOI: 10.1016/j.mehy.2006.11.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2006] [Accepted: 11/11/2006] [Indexed: 01/04/2023]
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24
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Abstract
In this review we summarize mechanisms of Ca(2+) signaling in microglial cells and the impact of Ca(2+) signaling and Ca(2+) levels on microglial function. So far, Ca(2+) signaling has been only characterized in cultured microglia and thus these data refer rather to activated microglia as observed in pathology when compared with the resting form found under physiological conditions. Purinergic receptors are the most prominently expressed ligand-gated Ca(2+)-permeable channels in microglia and control several microglial functions such as cytokine release in a Ca(2+)-dependent fashion. A large variety of metabotropic receptors are linked to Ca(2+) release from intracellular stores. Depletion of these intracellular stores triggers a capacitative Ca(2+) entry. While microglia are already in an activated state in culture, they can be further activated, for example, by exposure to bacterial endotoxin. This activation leads to a chronic increase of [Ca(2+)](i) and this Ca(2+) increase is a prerequisite for the release of nitric oxide and cytokines. Moreover, several factors (TNFalpha, IL-1beta, and IFN-gamma) regulate resting [Ca(2+)](i) levels.
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Affiliation(s)
- Katrin Färber
- Cellular Neuroscience, Max-Delbrueck-Center for Molecular Medicine, Robert-Rössle-Straβe 10, 13092 Berlin, Germany
| | - Helmut Kettenmann
- Cellular Neuroscience, Max-Delbrueck-Center for Molecular Medicine, Robert-Rössle-Straβe 10, 13092 Berlin, Germany
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25
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Lee DY, Park KW, Jin BK. Thrombin induces neurodegeneration and microglial activation in the cortex in vivo and in vitro: proteolytic and non-proteolytic actions. Biochem Biophys Res Commun 2006; 346:727-38. [PMID: 16777064 DOI: 10.1016/j.bbrc.2006.05.174] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Accepted: 05/24/2006] [Indexed: 12/27/2022]
Abstract
The present study evaluated the role of thrombin and its receptors in neurodegeneration and microglial activation. Immunocytochemical evidence indicated that intracortical injection of thrombin resulted in a significant loss of neurons and the activation of microglia in the rat cortex in vivo. Reverse transcription PCR and double-label immunocytochemistry further demonstrated the early and transient expression of pro-inflammatory cytokines and neurotoxic factors as well as their colocalization within activated microglia. The thrombin-induced loss of cortical neurons was partially blocked by N(G)-nitro-L-arginine methyl ester hydrochloride, a nitric oxide synthase inhibitor, and by NS-398, a cyclooxygenase-2 inhibitor, indicating that the activation of microglia is involved in the neurotoxicity of thrombin in the cortex in vivo. In addition, thrombin activated cortical microglia in culture, as indicated by the expression of several pro-inflammatory cytokines and produced cell death in microglia-free, neuron-enriched cortical cultures. However, agonist peptides for thrombin receptors, including protease-activated receptor-1 (SFLLRN), -3 (TFRGAP), and -4 (GYPGKF), failed to activate microglia and were not neurotoxic in culture. Intriguingly, morphological and biochemical evidence indicated that thrombin-induced neurotoxicity but not microglial activation was prevented by hirudin, a specific inhibitor of thrombin. Collectively, the present data suggest that a non-proteolytic activity of thrombin activates microglia and that the proteolytic activity mediates its neurotoxicity.
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Affiliation(s)
- Da Yong Lee
- Neuroscience Graduate Program and Brain Disease Research Center, Ajou University School of Medicine, Suwon 443-721, Republic of Korea
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26
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Weinstein JR, Hong S, Kulman JD, Bishop C, Kuniyoshi J, Andersen H, Ransom BR, Hanisch UK, Möller T. Unraveling thrombin's true microglia-activating potential: markedly disparate profiles of pharmaceutical-grade and commercial-grade thrombin preparations. J Neurochem 2006; 95:1177-87. [PMID: 16271051 DOI: 10.1111/j.1471-4159.2005.03499.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Microglia are the resident immune cells of the CNS. Brain injury triggers microglial activation, leading to proliferation, changes in antigenic profile, NO production and cytokine release. It is widely believed that serum factors inundating the injured tissue can prompt this activation, leading to long-term phenotypic changes. We and others have recently reported that commercial-grade preparations of thrombin, a serine protease known for its central function in blood coagulation, activate microglial cells. Recent findings, however, have called into question the involvement of thrombin itself in the induction of microglial cytokine release and led us to systematically re-investigate the ability of the protease to induce a broad spectrum of microglial activation parameters. We used a pharmaceutical-grade recombinant human thrombin (rh-thr) and compared it with a commercial-grade plasma-derived bovine thrombin (pb-thr) preparation that has been used extensively in the literature, including in our own earlier report. We investigated the effect of these two thrombin preparations on proliferation, NO production, interleukin-6 and tumour necrosis factor-alpha release, intracellular calcium signaling and cell surface expression of CD95 (Fas) and CD40. Pb-thr induced robust responses in all variables tested. In contrast, rh-thr triggered calcium signals and induced small but significant changes in the expression of cell surface antigens, but had no effect on proliferation, NO production or cytokine release. Control studies assured equivalent thrombin potencies and excluded both species-specific effects and endotoxin (lipopolysaccharide) contamination as possible causes of the disparity. Our results indicate a substantially more restricted role for thrombin itself in microglial activation than previously appreciated, but point to several potentially important co-stimulatory effects. In addition, these results suggest that previous studies examining thrombin's activation of microglia should be cautiously re-interpreted.
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Affiliation(s)
- Jonathan R Weinstein
- Department of Neurology, School of Medicine, University of Washington, Seattle, Washington 98195, USA
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27
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Henrich-Noack P, Riek-Burchardt M, Baldauf K, Reiser G, Reymann KG. Focal ischemia induces expression of protease-activated receptor1 (PAR1) and PAR3 on microglia and enhances PAR4 labeling in the penumbra. Brain Res 2006; 1070:232-41. [PMID: 16403464 DOI: 10.1016/j.brainres.2005.10.100] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2005] [Revised: 10/25/2005] [Accepted: 10/31/2005] [Indexed: 11/27/2022]
Abstract
Thrombin significantly influences neurodegenerative processes after ischemia. The current literature suggests that the effects are mediated via protease-activated receptors 1, 3 and 4 (PAR1, 3, 4). Therefore, we investigated with immunohistochemical methods whether focal cerebral ischemia altered the expression of PARs in the rodent brain. For this purpose, we used the model of endothelin-induced occlusion of the middle cerebral artery and the model of transcranial permanent occlusion of the middle cerebral artery in mice. In contrast to the exclusively neuronal staining in the brain parenchyma of naïve animals, PAR1 and PAR3 occurred in addition on microglial cells in the penumbra after transient and after permanent focal ischemia. Although microglia activation could be detected for several weeks after the insult, PAR1 and PAR3 were traceable on microglia only 12 and 48 h after the insult, but not on day 7 post-ischemia. PAR4 was expressed, both in naïve and in ischemic animals, exclusively in neuronal cells. However, at the border zone and within the infarct area, enhanced immunohistochemical PAR4 signals were recognized. From our data, we conclude that PAR1 and PAR3 could be involved in thrombin-modulated initiation of post-ischemic inflammation and PAR4 may be associated with neuronal degeneration.
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Affiliation(s)
- Petra Henrich-Noack
- Institute for Neurobiochemistry, Medical Faculty, Otto-von-Guericke University, Leipziger Str. 44, 39120 Magdeburg, Germany.
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28
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Carson MJ, Thrash JC, Lo D. Analysis of microglial gene expression: identifying targets for CNS neurodegenerative and autoimmune disease. ACTA ACUST UNITED AC 2004; 4:321-30. [PMID: 15462610 DOI: 10.2165/00129785-200404050-00005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Microglia are the tissue macrophage of the central nervous system (CNS) and their activation is among the earliest signs of CNS dysfunction and disease. Because microglia express many macrophage markers, they are presumed to act primarily as effectors of CNS inflammation and destruction. While such responses are beneficial to the extent that they destroy CNS pathogens, these responses do have the potential to have neurotoxic outcomes. Consequently, therapies for many CNS neurodegenerative and inflammatory diseases have been directed at suppressing microglial function. There is evidence to suggest that microglia play an important role during CNS development and maintenance of CNS function that may go beyond simple defense against pathogens. Molecular analysis of microglial phenotypes and function has revealed three striking findings: (i) that microglia are a unique CNS-specific type of tissue macrophage; (ii) that they are highly heterogeneous within the healthy CNS; and (iii) that microglial responses are exquisitely tailored to specific regions of the CNS and specific pathological insults. We suggest that ubiquitous suppression (rather than targeted manipulation) of microglial function may fail to fully ameliorate CNS pathology and may even ultimately promote maladaptive outcomes.
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Affiliation(s)
- Monica J Carson
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California, USA.
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29
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Hanisch UK, van Rossum D, Xie Y, Gast K, Misselwitz R, Auriola S, Goldsteins G, Koistinaho J, Kettenmann H, Möller T. The microglia-activating potential of thrombin: the protease is not involved in the induction of proinflammatory cytokines and chemokines. J Biol Chem 2004; 279:51880-7. [PMID: 15452111 DOI: 10.1074/jbc.m408318200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The serine protease thrombin is known as a blood coagulation factor. Through limited cleavage of proteinase-activated receptors it can also control growth and functions in various cell types, including neurons, astrocytes, and microglia (brain macrophages). A number of previous studies indicated that thrombin induces the release of proinflammatory cytokines and chemokines from microglial cells, suggesting another important role for the protease beyond hemostasis. In the present report, we provide evidence that this effect is not mediated by any proteolytic or non-proteolytic mechanism involving thrombin proper. Inhibition of the enzymatic thrombin activity did not affect the microglial release response. Instead the cyto-/chemokine-inducing activity solely resided in a high molecular weight protein fraction that could be isolated in trace amounts even from apparently homogenous alpha- and gamma-thrombin preparations. High molecular weight material contained thrombin-derived peptides as revealed by mass spectrometry but was devoid of thrombin-like enzymatic activity. Separated from the high molecular weight fraction by fast protein liquid chromatography, enzymatically intact alpha- and gamma-thrombin failed to trigger any release. Our findings may force a revision of the notion that thrombin itself is a direct proinflammatory release signal for microglia. In addition, they could be relevant for the study of other cellular activities and their assignment to this protease.
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Affiliation(s)
- Uwe-Karsten Hanisch
- Department of Cellular Neurosciences, Max Delbrück Center for Molecular Medicine, D-13092 Berlin, Germany.
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