Role of Very-late Antigen-4 (VLA-4) in Myelin Basic Protein-primed T Cell Contact-induced Expression of Proinflammatory Cytokines in Microglial Cells

Subhajit Dasgupta,Malabendu Jana,Xiaojuan Liu,Kalipada Pahan

doi:10.1074/jbc.m301789200

Subhajit Dasgupta, Malabendu Jana + Show 2 more

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https://doi.org/10.1074/jbc.m301789200

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Abstract

The presence of neuroantigen-primed T cells recognizing self-myelin antigens within the CNS is necessary for the development of demyelinating autoimmune disease like multiple sclerosis. This study was undertaken to investigate the role of myelin basic protein (MBP)-primed T cells in the expression of proinflammatory cytokines in microglial cells. MBP-primed T cells alone induced specifically the microglial expression of interleukin (IL)-1beta, IL-1alpha tumor necrosis factor alpha, and IL-6, proinflammatory cytokines that are primarily involved in the pathogenesis of MS. This induction was primarily dependent on the contact between MBP-primed T cells and microglia. The activation of microglial NF-kappaB and CCAAT/enhancer-binding protein beta (C/EBPbeta) by MBP-primed T cell contact and inhibition of contact-mediated microglial expression of proinflammatory cytokines by dominant-negative mutants of p65 and C/EBPbeta suggest that MBP-primed T cells induce microglial expression of cytokines through the activation of NF-kappaB and C/EBPbeta. In addition, we show that MBP-primed T cells express very late antigen-4 (VLA-4), and functional blocking antibodies to alpha4 chain of VLA-4 (CD49d) inhibited the ability of MBP-primed T cells to induce microglial proinflammatory cytokines. Interestingly, the blocking of VLA-4 impaired the ability of MBP-primed T cells to induce microglial activation of only C/EBPbeta but not that of NF-kappaB. This study illustrates a novel role of VLA-4 in regulating neuroantigen-primed T cell-induced activation of microglia through C/EBPbeta

Highlights

Spleen and lymph nodes, organs that have been found to contain myelin basic protein (MBP) mRNA and protein in mouse, rat, and human
After nylon-wool column purification, MBP-primed T cells were ϳ98% pure as obtained by the FACS analysis [14]. We examined whether these purified MBP-primed T cells can induce the production of proinflammatory cytokines like IL-1␤ and tumor necrosis factor (TNF)-␣ in mouse BV-2 microglial cells
Normal T cells were unable to induce the production of IL-1␤ and TNF-␣ in BV-2 microglial cells (Fig. 2A)

Summary

Introduction

Spleen and lymph nodes, organs that have been found to contain myelin basic protein (MBP) mRNA and protein in mouse, rat, and human. According to the other view [3], T cells may be activated in the CNS periphery by the first encounter with myelin-related autoantigens such as MBP, proteolipid protein, and myelin oligodendrocyte glycoprotein. After activation, these potentially damaging T cells may cross the blood-brain barrier and accumulate in the CNS where they recognize autoantigens, proliferate, and trigger a broad-spectrum inflammatory cascade, leading to myelin degradation and clinical symptoms (1, 4 – 6). Verylate antigen-4 (VLA-4) molecules on T cell surface play an important role in contact-mediated microglial expression of proinflammatory cytokines through the regulation of microglial activation of CCAAT/enhancer-binding protein ␤ (C/ EBP␤) but not that of NF-␬B

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