Functional Identification Of Hepatic Stellate Cells From Mice Infected With Schistosoma Japonicum

Schistosomiasis,a parasitic disease,is one of the most important challenges to the population living in the epidemic areas.The person who infected with Schistosoma japonicum(Sj) without effective treatment can develop into advanced schistosomiasis. Advanced schistosomiasis can lead to serious consequences such as liver fibrosis or even cirrhosis.Research suggests that whatever the cause of liver injury,the cells and soluble factors contributing to this wound healing response are similar.The principal effector of hepatic fibrogenesis is now widely recognized as the activation of hepatic stellate cell(HSC).To date there are no prior studies in the relationship betwwen antigens released from different worm stages and activation of hepatic stellate cells in Schistosomiasis japonicum.Recent reports show that hepatic stellate cells function as antigen presentation cells involved in immune response.To our knowledge,virtually nothing is known about the function of antigen presentation in HSC from mice infected with S. japonicum.Our study focus on the activation and the antigen presentation function of HSCs isolated from mice in infection with Schistosomiasis japonicum.In this study,to observe the activation stage of HSC,α-SMA and Collagenα1 mRNA expressions of HSC stimulated by antigens from different worm stages in vivo and in vitro were analyzed by real-time PCR.Murine modles infected with Schistosomiasis japonicum were established.At 1,2,3weeks post infection,α-SMA and Collagenα1 mRNA expressions of HSC were analyzed by real-time PCR to clear the time point when HSC activateed in Schistosomiasis japonicum.Then the antigen presentation function of HSC was detected by CCK-8 cell proliferation assay.HSC was divided into MHCⅡ+HSC and MHCⅡ-HSC by magnetic separation.Cell proliferation assay and QuaniGene 2.0 Plex were taken to describe the diffrences of antigen-presenting function and fibriosis-related indicators between MHCⅡ+HSC and MHCⅡ-HSC.The main results are as follows:1. Schistosome antigens induce HSC activation Real-time PCR analysis showed that SEA(soluble egg antigen) and SWAP(soluble adult worm antigen) can not induce HSC activation in vitro. In vivo,α-SMA and Collagenα1 mRNA expressions of HSC were significantly increased,compared with that in control group.The result suggests that SEA and SWAP can promote the activation of HSC in vivo. HSC can be activated by SEA and SWAP in vivo but not in vitro which indicate that the fact that the microenvironment of HSCs in the fibrotic liver is complex and exposes HSC to a number of cellular and humoral interactions,whereas in vitro activation occurs in an artificial environment and does not include interactions with other cell types unless there is a high degree of contamination. OVA antigen induced HSC activation in vitro but not in vivo partly demonstrate that HSC activation may have the restriction of certain antigens.2. Phase characteristics of HSC activation Real-time PCR result showed thatα-SMA and Collagenα1 mRNA expressions of HSC were gradually increased with the infection,suggesting that the activation of HSC occuers before eggs deposited in liver. 3. Antigen presenting function of HSC Our experiments revealed that quiescent HSC do not possess the function of antigen presentation. But CD8+T cells were specifically stimulated by HSC activted by SEA and SWAP presenting SEA in the context of MHC-I. Similarly,CD4+ T cells were stimulated in the context of MHC-II. Activated HSC represents powerful antigen presenting function for inducing multiple T cell responses in Schistosoma japonicum infection.4. Functional features of HSC Cell proliferation assay showed that the antigen presenting function of MHCⅡ+HSC was powerful compared with MHCⅡ-HSC. The mRNA expression of TIMP-1 was higher in MHCⅡ-HSC than MHCⅡ+HSC, suggesting that MHCⅡ-HSC plays roles dominantly in the development of liver fibrosis.