Objective: To determine the effect of excessive induction of hepatocyte growth factor (HGF)/c-met signaling in fibroblasts derived from patients with systemic sclerosis (SSc).
Methods: Fibroblasts were obtained from skin of patients with SSc and healthy controls. The 2.4 kb interleukin 1alpha (IL-1alpha) cDNA was subcloned into pcDNA3 expression vector, which was stably transfected into normal fibroblasts by lipofection. HGF production in cultured fibroblasts was measured by ELISA. C-met protein (a receptor for HGF) in cultured fibroblasts was evaluated by immunocytochemistry using polyclonal anti-c-met antibody. Production of procollagen type I was estimated by an ELISA system using antibodies against procollagen type I C-peptide.
Results: Cultured skin fibroblasts expressed mRNA and protein of HGF constitutively in both SSc and control cultures. However, HGF production in SSc fibroblasts was significantly higher than in normal fibroblasts. In both SSc and normal fibroblasts, HGF production was dose dependently increased by the addition of recombinant IL-1alpha. Immunocytochemical staining revealed that c-met was spontaneously expressed in SSc fibroblasts, whereas no expression of c-met was detected in normal fibroblasts. C-met mRNA was expressed in normal fibroblasts transfected with the IL-1alpha gene. Addition of recombinant HGF (100 ng/ml) to cultured SSc fibroblasts significantly decreased procollagen type I production.
Conclusion: High concentration of HGF inhibited collagen production in cultured fibroblasts derived from patients with SSc. Overexpression of HGF/c-met appears to be a biological feedback response to the fibrotic process of SSc, suggesting that the antifibrotic effect of HGF might be used as a novel strategy for treatment of SSc.