Effects of TARC and MDC on Th2 response and liver fibrosis in mice with Schistosoma japonicum infection

Abstract

Objective To investigate the effects of thymus activation regulated chemokine (TARC)and macrophage-derived chemokine (MDC) on Th2 responses and liver fibrosis in Schistosoma japonicum infection.Methods Mice were infected by percutaneous infection with 20 cercariae of S.japonicum.The Th2 response in mesentenic lymph node(MLN) and liver was determined by intracellular cytokine staining (ICC)and ELISA.TARC and MDC mRNA level in MLN and liver were measured by quantitative real time PCR.The fibrosis was measured by the content of hepatic hydroxyproline.Results The hepatic Th2 responses were observed with similar time kinetics as those in the MLN,whereas IL-13-producing Th2 cells in the liver (5.3％) were more detectable than those in the MLN (about 3％).Additionally,liver fibrosis was aggravated during the S.japonicum infection.The hepatic hydroxyproline was 2.9μg/mg,5.1μg/mg and 8.3μg/mg at 5,7 and 10 weeks post infection.The mRNA levels of TARC and MDC in the MLN were 0.5 and 0.4 fold of uninfected mice while those levels in liver were significantly higher and 12.8 and 8.2 fold of those in uninfected mice at 7 weeks after infection.Meanwhile TARC and MDC in the liver maintained high level of mRNA in the chronic stage and were 3.8 and 4.4 fold of those in uninfected mice,respectively.Conclusion As specific chemokines for tissue recruitment of Th2 cells,TARC and MDC may play an important role in recruiting Th2 cells to liver to cause inflammatory responses and liver fibrosis. Key words: Schistosoma japonicum; Th2 response; Chemokine; Liver fibrosis