Z Gastroenterol 2009; 47 - P1_40
DOI: 10.1055/s-0029-1191794

Inhibitory effect of Tumor Necrosis Factor α, Interleukin 2, and Interferon γ on CTGF expression in cultured rat hepatocytes

I Peredniene 1, OA Gressner 1, B Lahme 1, K Rehbein 1, AM Gressner 1
  • 1Institut für Klinische Chemie und Pathobiochemie, Universitätsklinikum der RWTH Aachen

Introduction: Although inflammation typically precedes the development of fibrosis, the underlying regulatory mechanisms may be different. Liver residing cytokine producing CD4+ T-helper (Th) cells differentiate into Th1 (antifibrogenic) and Th2 (profibrogenic) subsets and modulate organ fibrosis. Connective tissue growth factor (CTGF/CCN2) has been implicated in the pathogenesis of hepatic fibrosis and suggested as an important downstream mediator of the fibrogenic master cytokine TGF-ß. Recently, we were the first to identify that hepatocytes (PC) are the major cellular source of CTGF in the liver.

Aim: To investigate the effect of selected Th1-type cytokines on CTGF protein expression and promoter activity in PC.

Materials and Methods: PC were isolated from male Sprague-Dawley rats by the two step collagenase method and cultured in HepatoZYME-SFM (GIBCOTM) or Dulbecco’s Modified Eagle’s Medium (DMEM) for 24h in presence (0,2%) or absence of fetal calf serum (FCS) and subsequently stimulated with cytokines. CTGF protein expression was examined by Western blotting and CTGF promoter activity by a hCTGF/CCN2-Promoter-luciferase gene reporter assay.

Results: TNF-α dose-dependently suppressed CTGF protein expression in PC cultured in DMEM with 0,2% FCS by up to 36%. The most effective TNF-α induced CTGF repression was observed in culture conditions without FCS (reduction by more than 50%). Similarly, TNF-α suppressed CTGF promoter activity in PC cultured in HepatoZYME (75% of control) and DMEM with 0,2% FCS (72% of control). A smaller inhibitory effect on the CTGF promoter was achieved by stimulation with IL-2 and IFN-γ in DMEM with 0,2% FCS. IL-12 had no effect on CTGF expression.

Conclusion: TNF-α, IL-2 and IFN- γ but not IL-12 suppressed CTGF protein expression and transcriptional activation in cultured rat PC. This study is meant to pioneer future investigations on the modulatory role of the Th1/Th2 response in the pathogenesis of liver fibrosis.