Tumor Necrosis Factor-α in Ocular Mucous Membrane Pemphigoid and Its Effect on Conjunctival Fibroblasts

Abstract

First, to determine whether tumor necrosis factor-(TNF)-alpha is expressed in the conjunctiva of ocular mucous membrane pemphigoid (MMP) and the consequences of systemic immunosuppressive treatment on this expression. Second, to investigate the in vitro effects of TNFalpha on human conjunctival fibroblasts. The expression of TNFalpha in conjunctival tissues of patients with actively inflamed ocular MMP (n = 10), patients with clinically noninflamed ocular MMP after systemic immunosuppressive treatment (n = 10), and normal subjects (n = 10) was studied by immunohistochemistry. The effect of TNFalpha on functional assays of human conjunctival fibroblast activity were investigated, including migration, collagen lattice contraction, matrix metalloproteinase (mmp), and tissue inhibitor of matrix metalloproteinase (timp) secretion, proliferation, and surface expression of HLA-DR, ICAM, CD80, CD86, CD40, CD40-ligand. In active ocular MMP, TNFalpha is expressed by a large number of stromal infiltrating cells (234 cells/mm(2)), and although the level of stromal TNFalpha expression is significantly reduced after immunosuppressive treatment (90 cells/mm(2)), these levels are still significantly elevated compared with normal conjunctiva (10 cells/mm(2), P < 0.05). TNFalpha stimulates increased migration by conjunctival fibroblasts (P < 0.001), increased production of mmp-9 (P = 0.01), decreased production of timp-2 (P = 0.01) and timp-4 (P = 0.04), and upregulated expression of CD40 and ICAM (P = 0.04). No significant effects of TNFalpha on fibroblast proliferation or collagen lattice contraction were detected. Increased conjunctival expression of TNFalpha in ocular MMP suggests that systemic TNFalpha antagonists are likely to be effective in controlling severe disease unresponsive to conventional systemic immunosuppression. Residual TNFalpha expression persists in clinically noninflamed disease. TNFalpha appears to have profibrotic and proinflammatory effects on human conjunctival fibroblasts.