HSCs are liver pericytes that reside in the space between parenchymal cells and sinusoidal endothelial cells of the liver.[2] HSCs are rich in vitamin A and store nearly 80% of retinoids of the whole body in its lipid droplets in the cytoplasm.[3, 4] Interestingly, recent studies[5-15] suggest that HSCs participate in the liver immunity. In this paper, we review the recent development in HSC-mediated

immunity and the significance of these new observations. HCV represents one of the major causes of liver fibrosis. The rate of progression of liver fibrosis varies widely in the chronic HCV infection, and progresses to cirrhosis within 20 years in an estimated 20–30% of individuals with chronic HCV infection.[16] The role of HSCs in YAP-TEAD Inhibitor 1 solubility dmso HCV-mediated liver fibrosis has been well documented. HCV-infected hepatocytes release transforming growth factor-β1 (TGF-β1) and other profibrogenic factors that differentially modulate HSC expression of AZD0530 chemical structure several key genes involved in liver fibrosis.[17] HCV infection-induced hepatocyte

apoptosis is a common feature in chronic HCV infection.[18, 19] Apoptosis results in the generation of apoptotic bodies (ABs), which are subsequently cleared by phagocytosis. Several studies showed that HSCs have the ability to engulf ABs through phagocytosis, which can trigger a profibrogenic response.[20, 21] It was reported that ABs derived from HCV-infected Huh7 cells exhibited a more pronounced effect on profibrotic genes expression in HSCs than HCV-negative ABs.[22] Besides the indirect effects of HCV on HSCs function through infected

hepatocytes, several studies[23-26] PLEK2 indicated that there is also a direct contact between HCV and HSCs. The potential interaction between HSCs and HCV is suggested by the observation that HSCs express high levels of CD81 protein,[23] a key entry coreceptor for HCV.[24] It has been demonstrated that the HCV E2 protein can directly bind to CD81 on HSC surface, inducing fibrogenic effects on HSCs.[25] In addition to HCV envelope protein, HCV core and nonstructural proteins have also been shown to affect HSC functions.[26] Recombinant HCV core and NS3 proteins could increase intracellular calcium concentration and reactive oxygen species production in activated HSCs.[26] HCV core protein could increase HSC proliferation, and NS3-NS5 protein preferentially induced pro-inflammatory cytokines in HSCs. The roles of HSCs in HCV infection-mediated liver fibrosis are summarized in Table 1. HSCs have recently been implicated to play a novel role in the liver immunity. It was reported that HSCs could induce vigorous natural killer T (NKT) cell responses in vitro and in vivo, and promote homeostatic proliferation of NKT cells.[13] In addition, HSCs could elicit antigen-specific T cells and inhibit bacterial infection in a Listeria monocytogenes infection model.