Microglia use multiple mechanisms to mediate interactions with vitronectin; non-essential roles for the highly-expressed αvβ3 and αvβ5 integrins

Journal of Neuroinflammation

Richard Milner¹  Ulrich Tigges¹  Amin Boroujerdi¹  Jennifer V Welser-Alves¹ 

[1] Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA

关键词: MMP-9;    adhesion;    integrin;    vitronectin;    extracellular matrix;    microglia;   

Others  :  1213015
DOI  :  10.1186/1742-2094-8-157

 received in 2011-08-05, accepted in 2011-11-10,  发布年份 2011

【 摘 要 】

Background

As the primary resident immune cells, microglia play a central role in regulating inflammatory processes in the CNS. The extracellular matrix (ECM) protein vitronectin promotes microglial activation, switching microglia into an activated phenotype. We have shown previously that microglia express two vitronectin receptors, αvβ3 and αvβ5 integrins. As these integrins have well-defined roles in activation and phagocytic processes in other cell types, the purpose of the current study was to investigate the contribution of these two integrins in microglial activation.

Methods

Microglial cells were prepared from wild-type, β3 integrin knockout (KO), β5 integrin KO or β3/β5 integrin DKO mice, and their interactions and activation responses to vitronectin examined in a battery of assays, including adhesion, expression of activation markers, MMP-9 expression, and phagocytosis. Expression of other αv integrins was examined by flow cytometry and immunoprecipitation.

Results

Surprisingly, when cultured on vitronectin, microglia from the different knockout strains showed no obvious defects in adhesion, activation marker expression, MMP-9 induction, or phagocytosis of vitronectin-coated beads. To investigate the reason for this lack of effect, we examined the expression of other αv integrins. Flow cytometry showed that β3/β5 integrin DKO microglia expressed residual αv integrin at the cell surface, and immunoprecipitation confirmed this finding by revealing the presence of low levels of the αvβ1 and αvβ8 integrins. β1 integrin blockade had no impact on adhesion of β3/β5 integrin DKO microglia to vitronectin, suggesting that in addition to αvβ1, αvβ3, and αvβ5, αvβ8 also serves as a functional vitronectin receptor on microglia.

Conclusions

Taken together, this demonstrates that the αvβ3 and αvβ5 integrins are not essential for mediating microglial activation responses to vitronectin, but that microglia use multiple redundant receptors to mediate interactions with this ECM protein.

【 授权许可】

   
2011 Welser-Alves et al; licensee BioMed Central Ltd.

【 图 表 】

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

【 参考文献 】

• [1]Carson MJ: Microglia as liasons between the immune and central nervous systems: functional implications for multiple sclerosis. Glia 2002, 40:218-231.
• [2]Hanisch UK, Kettenmann H: Microglia: active sensor and versatile effector cells in the normal and pathologic brain. Nat Neurosci 2007, 10:1387-1394.
• [3]Raivich G, Bohatschek M, Kloss CU, Werner A, Jones LL, Kreutzberg GW: Neuroglial activation repertoire in the injured brain: graded response, molecular mechanisms and cues to physiological function. Brain Res Brain Res Rev 1999, 30:77-105.
• [4]Barnett MH, Prineas JW: Relapsing and remitting multiple sclerosis: pathology of the newly forming lesion. Ann Neurol 2004, 55:458-468.
• [5]Hickey WF: The pathology of multiple sclerosis: a historical perspective. J Neuroimmunol 1999, 98:37-44.
• [6]Ransohoff RM: Mechanisms of inflammation in MS tissue: adhesion molecules and chemokines. J Neuroimmunol 1999, 98:57-68.
• [7]Trapp BD, Bo L, Mork S, Chang A: Pathogenesis of tissue injury in MS lesions. J Neuroimmunol 1999, 98:49-56.
• [8]Felding-Habermann B, Cheresh DA: Vitronectin and its receptors. Curr Opin Cell Biol 1993, 5:864-868.
• [9]Purves LR, Brown G, Linton N: Fibronectin levels in normal subjects and patients admitted to a respiratory intensive care unit. S Afr Med J 1982, 61:733-736.
• [10]Milner R, Campbell IL: The extracellular matrix and cytokines regulate microglial integrin expression and activation. J Immunol 2003, 170:3850-3858.
• [11]Milner R, Crocker SJ, Hung S, Wang X, Frausto RF, Del Zoppo GJ: Fibronectin- and Vitronectin-Induced Microglial Activation and Matrix Metalloproteinase-9 Expression Is Mediated by Integrins α5β1 and αvβ5. J Immunol 2007, 178:8158-8167.
• [12]Han MH, Hwang SI, Roy DB, Lundgren DH, Price JV, Ousman SS, Fernald GH, Gerlitz B, Robinson WH, Baranzini SE, et al.: Proteomic analysis of active multiple sclerosis lesions reveals therapeutic targets. Nature 2008, 451:1076-1081.
• [13]Sobel R, Chen M, Maeda A, Hinojoza J: Vitronectin and integrin vitronectin receptor localisation in multiple sclerosis lesions. J Neuropathol Exp Neurol 1995, 54:202-213.
• [14]Sobel RA, Mitchell ME: Fibronectin in multiple sclerosis lesions. Am J Pathol 1989, 135:161-169.
• [15]Teesalu T, Hinkkanen AE, Vaheri A: Coordinated induction of extracellular proteolysis systems during experimental autoimmune encephalomyelitis in mice. Am J Pathol 2001, 159:2227-2237.
• [16]Hodivala-Dilke KM, McHugh KP, Tsakiris DA, Rayburn H, Crowley D, Ullman-Cullere M, Ross FP, Coller BS, Teitelbaum S, Hynes RO: Beta3-integrin-deficient mice are a model for Glanzmann thrombasthenia showing placental defects and reduced survival. J Clin Invest 1999, 103:229-238.
• [17]Huang X, Griffiths M, Wu J, Farese RV, Sheppard D: Normal development, wound healing, and adenovirus susceptibility in beta5-deficient mice. Mol Cell Biol 2000, 20:755-759.
• [18]Milner R, Huang X, Wu J, Nishimura S, Pytela R, Sheppard D, ffrench-Constant C: Distinct roles for astrocyte αvβ5 and αvβ8 integrins in adhesion and migration. J Cell Sci 1999, 112:4271-4279.
• [19]Nandrot EF, Kim Y, Brodie SE, Huang X, Sheppard D, Finnemann SC: Loss of synchronized retinal phagocytosis and age-related blindness in mice lacking αvβ5 integrin. J ExpMed 2004, 200:1539-1545.
• [20]Milner R, Campbell IL: Cytokines regulate microglial adhesion to laminin and astrocyte extracellular matrix via protein kinase C-dependent activation of the α6β1 integrin. J Neurosci 2002, 22:1562-1572.
• [21]Milner R, ffrench-Constant C: A developmental analysis of oligodendroglial integrins in primary cells: changes in αv-associated β subunits during differentiation. Development 1994, 120:3497-3506.
• [22]Heo JH, Lucero J, Abumiya T, Koziol JA, Copeland BR, del Zoppo GJ: Matrix metalloproteinases increase very early during experimental focal cerebral ischemia. J Cereb Blood Flow Metab 1999, 19:624-633.
• [23]Milner R: Microglial expression of alphavbeta3 and alphavbeta5 integrins is regulated by cytokines and the extracellular matrix: beta5 integrin null microglia show no defects in adhesion or MMP-9 expression on vitronectin. Glia 2009, 57:714-723.
• [24]Finnemann SC, Bonilha VL, Marmorstein AD, Rodriguez-Boulan E: Phagocytosis of rod outer segments by retinal pigment epithelial cells requires alpha v beta 5 integrin for binding but not for internalization. Proc Natl Acad Sci USA 1997, 94:12932-12937.
• [25]Finnemann SC, Rodriguez-Boulan E: Macrophage and retinal pigment epithelium phagocytosis: apoptotic cells and photoreceptors compete for alpha v beta 3 and alpha v beta 5 integrins, and protein kinase C regulates alpha v beta 5 binding and cytoskeletal linkage. J Exp Med 1999, 190:861-874.
• [26]Hemler ME: VLA proteins in the integrin family: Structures, functions, and their role on leucocytes. Ann Rev Immunol 1990, 8:365-400.
• [27]Milner R, Frost EE, Nishimura S, Delcommenne M, Streuli C, Pytela R, ffrench-Constant C: Expression of αvβ3 and αvβ8 integrins during oligodendrocyte precursor differentiation in the presence and absence of axons. Glia 1997, 21:350-360.
• [28]Bodary SC, McLean JW: The integrin β1 subunit associates with the vitronectin receptor αv subunit to form a novel vitronectin receptor in a human embryonic kidney cell line. J Biol Chemistry 1990, 265:5938-5941.
• [29]Miceli MV, Newsome DA, Tate DJJ: Vitronectin is responsible for serum-stimulated uptake of rod outer segments by cultured retinal pigment epithelial cells. Invest Opthalmol Vis Sci 1997, 38:1588-1597.
• [30]McHugh KP, Hodivala-Dilke K, Zheng MH, Namba N, Lam J, Novack D, Feng X, Ross FP, Hynes RO, Teitelbaum SL: Mice lacking beta3 integrins are osteosclerotic because of dysfunctional osteoclasts. J Clin Invest 2000, 105:433-440.
• [31]Brooks P, Clark RAF, Cheresh DA: Requirement for vascular integrin αvβ3 for angiogenesis. Science 1994, 264:569-571.
• [32]Friedlander M, Brooks P, Shaffer RW, Kincaid CM, Varner JA, Cheresh DA: Definition of two angiogenic pathways by distinct αv integrins. Science 1995, 270:1500-1502.
• [33]Reynolds LE, Wyder L, Lively JC, Taverna D, Robinson SD, Huang X, Sheppard D, Hynes RO, Hodivala-Dilke K: Enhanced pathological angiogenesis in mice lacking beta3 integrin or beta3 and beta5 integrins. Nat Med 2002, 8:27-34.
• [34]Li L, Welser JV, Milner R: Absence of the αvβ3 integrin dictates the time-course of angiogenesis in the hypoxic central nervous system: accelerated endothelial proliferation correlates with compensatory increases in α5β1 integrin expression. J Cereb Blood Flow Metab 2010, 30:1031-1043.
• [35]Jacques TS, Relvas JB, Nishimura S, Pytela R, Edwards GM, Streuli CH, ffrench-Constant C: Neural precursor chain migration and division are regulated through different β1 integrins. Development 1998, 125:3167-3177.
• [36]Okada Y, Copeland BR, Hamann GF, Koziol JA, Cheresh DA, del Zoppo GJ: Integrin αvβ3 is expressed in selective microvessels following focal cerebral ischemia. Am J Pathol 1996, 149:37-44.
• [37]Wei L, Erinjeri JP, Rovainen CM, Woolsey TA: Collateral growth and angiogenesis around cortical stroke. Stroke 2001, 32:2179-2184.
• [38]Koistinen P, Heino J: The selective regulation of αvβ1 integrin expression is based on the hierarchical formation of αv-containing heterodimers. J Biol Chem 2002, 277:24835-24841.