Effects of visfatin on proliferation and collagen synthesis in rat cardiac fibroblasts.

The proliferation of cardiac fibroblasts (CFs) and excessive extracellular matrix protein accumulation are the basic pathological processes of myocardial fibrosis. Visfatin is a novel adipokine involved in the regulation of inflammatory cytokines, however, the effects of visfatin on proliferation and collagen synthesis of CFs are unclear. The aim of this study was to determine whether visfatin has any effect on the proliferation and collagen synthesis in rat CFs. Incorporation of [ (3)H]-thymidine and [ (3)H]-proline were used for evaluating DNA and collagen synthesis. Flow cytometry techniques were adopted to analyze cell cycle. Enzyme-linked immunosorbent assay was used for measuring collagen type I and III production. RT-PCR and Western blot analysis were used for determining procollagen I and III mRNA expression and protein production. The inhibitors used for pathway determination were: wortmannin [phosphatiylinositol 3-kinase (PI3K)], SB203580 [p38 mitogen-activated protein kinase (MAPK)], PD98059 [extracellular signal-regulated kinase (ERK)1/2)], and JNK inhibitor II [c-Jun NH 2-terminal kinase (JNK)]. We demonstrated that visfatin significantly increased DNA and collagen synthesis in a dose- and time-dependent manner. Cell cycle analysis showed that visfatin increased S-stage percentage and proliferation index in a dose- and time-dependent manner. It was also found that visfatin upregulated collagen I and III production, procollagen I and III mRNA expression and protein production. These effects were diminished by SB203580, wortmannin, and PD98059, but not by JNK inhibitor II. These results suggest that visfatin promote CFs proliferation and collagen synthesis via p38MAPK, PI3K, and ERK 1/2 pathways rather than JNK pathways, which also indicate that visfatin might play a role in myocardial fibrosis. Georg Thieme Verlag KG Stuttgart * New York.