Tumor necrosis factor-alpha processing inhibitor-1 inhibits skin fibrosis in a bleomycin-induced murine model of scleroderma.

Elevated serum concentration of soluble tumor necrosis factor receptor p55 (sTNFRp55) is known to correlate with the severity of systemic sclerosis (SSc). However, it has not been verified whether this increase contributes to the pathogenesis of SSc. In this study, we found that sTNFRp55 also is increased in the bleomycin (BLM)-induced murine model of SSc. Therefore, we examined the effect of tumor necrosis factor-alpha processing inhibitor-1 (TAPI-1), the inhibitor of TNFRp55 sheddase, in this model. TAPI-1 was administered weekly to mice with skin fibrosis induced by daily BLM injections. TAPI-1 significantly suppressed BLM-induced skin thickness and the number of myofibroblasts. It also inhibited the increase of serum sTNFRp55 after 3 weeks of BLM injections. The mRNA expression of collagen type I alpha1, transforming growth factor-beta1 and alpha smooth muscle actin were decreased by TAPI-1 administration. Taken together, these findings indicate that targeting the TNFalpha converting enzyme might be a new type of therapy for patients with SSc.