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Objective. To determine the role of tumor necrosis factor receptor p55 (TNFRp55)-mediated signaling in the pathogenesis of scleroderma.Methods. A murine model of scleroderma that closely resembles systemic sclerosis in humans was used. Wild-type and TNFRp55-deficient (TNFRp55 ؊/؊ ) mice received a subcutaneous injection of bleomycin each day. The extent of skin fibrosis was determined by measurements of the dermal thickness, as well as histologic examinations. Expression levels of fibrogenic cytokines, procollagen ␣1, and matrix metalloproteinase 1 (MMP-1), MMP-2, and MMP-9 messenger RNA (mRNA) were analyzed, both in vivo and in vitro, by reverse transcriptase-polymerase chain reaction assay or Western blotting.Results. TNFRp55 ؊/؊ mice began to develop severe sclerotic changes of the dermis on day 3 of the subcutaneous injections of bleomycin, while wild-type mice did not. The expression levels of fibrogenic cytokines, procollagen ␣1, and MMP-2 and MMP-9 mRNA were unaffected in the skin of both wild-type and TNFRp55 ؊/؊ mice, with or without bleomycin treatment. Induction of MMP-1 expression was significantly inhibited in the skin from bleomycin-treated TNFRp55 ؊/؊ mice, and this phenomenon was also observed in vitro.Conclusion. These results indicated that signaling mediated by TNFRp55 plays an essential role in MMP-1 expression and a key role in the collagen degradation process in this murine model. This study might provide a basis for understanding the pathogenesis of scleroderma and formulating therapeutic intervention.

The outcome reported here suggests that the combination therapy of Pred/CsA and IVIG-CPM appears to be useful for the treatment of dermatomyositis with pulmonary, infectious and mental complications.

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