The Detection And Analysis Of Tfh Cell And Transcription Factor "Achaete-scute Homologue 2 (Ascl-2)" In Chronic Hepatitis B Infection

Hepatitis B Virus(HBV)infection is an infectious disease which mainly induces acute or chronic liver injury.Clinical symptoms of HBV infection include abdominal discomfort,liver pain,fatigue,etc.Some patients may have jaundice,fever and severe liver injury.HBV-infected patients often develop chronic liver disease,and a small number of patients can develop into liver fibrosis,or even hepatoma.There are approximately 300 million HBV-infected people worldwide,and about 1 million people of them die each year from hepatitis B-related diseases.HBV can cause persistent inflammation and viremia,and these complications also increase the risk of the severe liver damage and cancer development.After acute infection with HBV,some patients can quickly eliminate the virus,but there are still patients with persistent infection,which causes chronic liver damage and induces liver fibrosis.Currently,chronic hepatitis B(CHB)can be controlled but hard to cure.The treatment of CHB patients can prevent or slow the progression of the disease and reduce complications,but it is impossible toeradicate HBV and reverse liver damage currently.The progression of HBV infection depends on the interaction between the virus and the host immune system,and also the immune balance generated during this process.Innate and adaptive immune regulations are the important factors in HBV progression.Although the adaptive immune response and its signal transduction during HBV infection have been extensively studied,there are still many unknown areas to be explored.CD4+ T cells are the most critical cells that help B lymphocytes to produce HBV specific antibodies,and the responses of those cells is the key factor in determining the production of antibodies by B lymphocytes.T follicular helper cell(Tfh cell),as a special subset of CD4+ T cells,can regulate adaptive immune response through the regulation of B cell function.Recent studies have found that Tfh cells which localize in lymphoid follicles,can induce the formation of germinal centers(GC),and assist B lymphocyte activation,thereby,promoting the production of viral spicific high-affinity antibodies.Changes of Tfh cell activity during HBV infection involve multiple regulations,in which transcription factor network plays important role.Previous studies have found that B-cell lymphoma 6(Bcl-6)is a key transcription factor involved in Tfh cell differentiation and proliferation.However,in recent years,another special transcription factor “achaete-scute homologue 2(Ascl-2)” has been discovered,which may initiate the Bcl-6-mediated Tfh differentiation process.The Ascl-2 guides the differentiation process of Tfh cells and participates in the differentiation of Tfh cells.Objective:To detect the expression of important molecules in CD4+ T cells and Tfh cells in peripheral blood mononuclear cells(PBMCs)in patients with CHB,and to analyze the correlation between status of Tfh cells and liver function,identifying the role of Ascl-2in Tfh cells during chronic HBV infection.Methods:50 peripheral blood samples from CHB patients in the patients of tangdu Hospital from September 2015 to June 2016 were collected,and the clinical information related to the treatment was analyzed.Patients enrolled in the study were diagnosed without other viral infections(HIV,HAV,HCV,HDV,HEV,etc.),autoimmune diseases and Inherited MetaholicLiver Diseases.Peripheral blood samples from 35 healthy volunteerswere also taken as the control group.Flow cytometry was used to analyze the changes of CD4+ T and Tfh lymphocytes in peripheral blood,and the expression of important signal molecules on Tfh cells such as PD-1 were examined.ELISA was used to detect IL-4,IL-17 and IL-21 in serum.The levels of cytokines(such as IFN-γ)were analyzed from isolated Tfh cells.Real-time quantitative PCR was used to detect the expression of Ascl-2mRNA Tfh cells.The liver function was investigated by automatic biochemical analyzer.Correlattion between the analyzed indexes and HBV infection were determined.Independent sample t-test was used for comparison between groups,and correlation analysis was performed using Person correlation analysis.Result:Compared with healthy controls:(1)The proportion of CD4+CXCR5+ Tfh and CD4+CXCR5+PD-1+ Tfh cells in patients with chronic HBV infection was significantly up-regulated(P<0.05);(2)The expression of Ascl-2 mRNA was increased in patients with chronic HBV infection,the difference was statistically significant(P<0.05);(3)Serum IL-21,IL-17 in patients with chronic HBV infection were also significantly increased(P<0.05).Conclusions:The frequency and the surface molecules of Tfh cells in CHB patients were significantly different from those of healthy donors,suggesting that the Tfh cells are closely related to the immune response of HBV infection.Ascl-2 may be involved in the abnormal differentiation of Tfh cells in HBV patients.