Pentoxifylline prevents pig serum-induced rat liver fibrosis by inhibiting interleukin-6 production

Background/Aim: Pig serum-induced rat liver fibrosis is a model of liver fibrosis in the absence of obvious hepatocyte injury. Penoxifylline (PTX), a xanthine derivative, which is a well-known suppressor of tumor necrosis factor-α (TNF-α) production from inflammatory cells, has also been shown to inhibit the growth of hepatic stellate cells and to inhibit collagen synthesis in these cells in vitro. We investigated the effect of PTX on pig serum-induced liver fibrosis in vivo, and assessed the mechanisms of prevention of fibrogenesis by this drug. Methods: Male Wistar rats were given intraperitoneal injections of 0.5 ml normal pig serum twice a week for 10 weeks with or without concomitant oral administration of PTX (20 mg/kg). Results: Rats that received pig serum showed significant liver fibrosis, and their serum interleukin-6 (IL-6) and hyaluronic acid levels were significantly increased. The serum levels of IL-6 were well correlated with the serum levels of hyaluronic acid, and increased as the liver fibrosis progressed. Penoxifylline prevented the development of fibrosis in this animal model and reduced the serum levels of IL-6 in a dose-dependent manner. In vitro, by the addition of PTX to the culture medium of the rat hepatic stellate cells (HSCs), the proliferation of the HSCs was significantly inhibited and IL-6 in the culture supernatant was also reduced significantly. Exogenous addition of IL-6 partially restored the proliferation. Conclusion: Penoxifylline prevents pig serum-induced rat liver fibrosis by inhibiting the proliferation of HSCs and by inhibiting the production of IL-6 from HSCs.