The Research On Functions Of Natural And Acquired Immunity In Chronic HBV Infection

Hepatitis B virus (HBV) infection is a global public health problem.Approximately 2 billion people have been infected HBV worldwide. HBV can usually escape early and late immune response leading to chronic liver disease-chronic hepatitis B, liver cirrhosis, liver failure and hepatic cellular carcinoma.Current international researches have shown that the outcome of HBV infection was related to the virus,liver microenviroment and anti-viral response of host,among which immune response in chronic hepatitis B was the most important mechanism in this process, involving innate immunity,acquired immunity (cellular immunity and humoral immunity).It is widely accepted that cytotoxic T cell(CTL) response to HBV infection was the primary effector cells by killing infected cells and clearing the virus,however,CTL can also induce hepatic damage.The immnue response not only eliminate the virus at early stage,but also lead to necrosisi of a large numeber of liver cells including acute severe hepaitits and even death.However,more and more evidences demonstrated that innate immnue played an important role in the outcome of HBV infection and the pathogenensis of chronic HBV infection. The researchs on the functions of NK cells as the main component of innate immnue could induce liver damage or clear virus in the chronic HBV process was uncertain. It is reported that cytokines as immnue-regulatory medium could inhibit virus replication and induce liver damege. Bacing on the complex of the immnue system and diversity of the disease spectrum of HBV infection,the researchs on the immnue of HBV infection was uncertain.(1)The number,the expressions of activatory and inhibitory receptors,the secretion of IFN-y of NK cells were tested by flow cytometry in the patients of chronic HBV infection.The cytotoxicity was detected by the lactate dehydrogenase (LDH) test measures.The correlation analysis was done between the NK cells and the clinical parameters.As to the significant changed receptor,the functional research were done in-vitro blockage.(2)We determined three IL28B single gene polymorphisms (rs12979860, rs12980275 and rs8099917) by pyrosequencing in 203 individuals with chronic HBV infection,203 individuals with self-limited HBV infection, and 203 individuals negative for all HBV seromarkers. IL28B serum levels were evaluated in all subjects by ELISA.(3)Tregs and T lymphocytes were tested by flow cytometry in HBV-cirrhotic and HCV-cirrhotic patients. Levels of Th cytokines were determined by CBA.Furthermore,the correlation analysis was done between the lymphocytes,the levels and the clinical parameters.The following are the major results obtained in the study.(1)No difference was found in the proportions of NK cells, CD3-CD56highNK, CD3-CD56lowNK and the secretion of IFN-γin different chronic HBV infection groups and healthy controls.(2)The activatory receptor NKP46 in inactive HBsAg carriers was higher than that in chronic HBV carrier,HBeAg positive CHB and healthy controls groups.The inhibitory receptor CD158a was higher in chronic HBV carriers than that in the inactive HBsAg carriers and HBeAg positive CHB.(3)CD107a as the killer index of NK cells was higher in immune-active phase than in immnue-tolerant phase.After in-vitro blockage NKP46,the cytotoxicity of NK cells to target cells(K562) and hepatoma cell lines (HepG2,HepG2.215) was decreased.(4)The association between genotype, allele frequencies of IL28B with alanine aminotransferase levels and HBV DNA was established.(5)The serum IL28B level was lower in patients with chronic HBV infection than in the self-limited HBV-infected or healthy subjects. The serum IL28B level was correlated with the subject's genotype.(6)The proportions of lymphocyte subsets were significantly different between the cirrhotic groups and healthy controls. The CD4/CD8 ratio,CD3+CD4+cells and Tregs were higher, while the CD3+CD8+ cells were lower in the cirrhosis groups than in the healthy control group. The increase in the CD4/CD8 ratio was a combined result of a relative increase in CD3+CD4+cells and decrease in CD3+CD8+ cells. There were no significant differences in lymphocyte subsets between the two cirrhotic groups.(7)Th2 cytokines(IL-6) concentrations were higher in cirrhotic patients than in controls. Thl cytokines (IFN-y) was dramatically higher in HBV-cirrhotic patients than that in HCV-cirrhotic patients and healthy controls. The IFN-y/IL-6 ratio in cirrhotic groups was dramatically lower than in controls.In conclusion,our study show that there is a wide range of immunological abnormalities,including innate immune(NK cells),acquired immune(T cells and Tregs) and cytokines(IFN-y,IL-6 and IL-28B).As a complex multi-gene disease,chronic HBV infection may be resulted from combination of immnue cells and cytokines,instead of single factor.