Paclitaxel inhibits TGF-β1 signaling between biliary epithelial cells and myofibroblasts in proliferative cholangitis

초록

Paclitaxel inhibits TGF-b1 signaling between biliary epithelial cells and myofibroblasts in proliferative cholangitis. Ho-soon Choi, Christopher E. Savard, Sum P. Lee. VA Hospital, University of Washington Proliferative cholangitis is characterized by epithelial hyperplasia and extensive fibrosis around bile ducts. A single intraluminal dose of paclitaxel (PT) suppressed these features in a rat model of proliferative cholangitis, which suggested its potential use as an agent to prevent fibrosis in biliary disease. To determine the mechanisms of the PT effects, we investigated the effects of PT on the expression and secretion of a fibrogenic cytokine, TGF-b1, by mouse gallbladder epithelial cells and human gallbladder myofibroblasts, their cellular cross talk through TGF-b1, and the synthesis of type I collagen by the myofibroblasts. Mouse gallbladder epithelial cells in Transwell inserts were grown in the presence of gallbladder myofibroblasts in the lower well. The effects of bacterial lipopolysaccharide (LPS) and/or PT on cytokine synthesis by the cells were measured by ELISA and RT-PCR. In myofibroblasts, type I collagen protein and mRNA and TGF-b1 mRNA expression were also measured. Results: The epithelial cells were more sensitive to PT (IC50=0.01mM) than the myofibroblasts (IC50=2mM). When LPS was applied apically to the epithelial cells, TGF-b1 protein was prominently secreted into the basolateral medium by 48 hours; this response was inhibited by PT. Expression of TGF-b1 mRNA was comparably increased by LPS and decreased by Paclitaxel. Stimulation of myofibroblasts with LPS or exogenous TGF-b1 increased type I collagen protein in the cells and medium, and both effects were inhibited by PT. LPS and TGF-b1 also up-regulated mRNA for both TGF-b1 and type I collagen, and PT slightly inhibited these responses. Conclusions: Mouse gallbladder epithelial cells can communicate with myofibroblasts via cytokines such as TGF-b1, and PT can modify this interaction by inhibiting TGF-b1 production, leading to decreased collagen deposition. We propose that these mechanisms account for the reduction of fibrosis by PT in the rat model of proliferative cholangitis.