The Role Of Th17Cells In The Pathogenesis Of Chronic Hepatitis B And Its Aggravation

Objective:Chronic hepatitis B (CHB) is one of the common and frequent diseases in China. For various reasons, some cases will progress to liver failure, among which acute-on-chronic liver failure (ACLF) is more common. In the present study, we examined the peripheral Thl7cells frequencies in peripheral blood mononuclear cells (PBMCs), the expressions of intrahepatic IL-17+cells from the patients with CHB and hepatitis B virus (HBV)-related ACLF, and the kinetic characteristics of serum IL-17levels in the HBV-related ACLF patients to explore the role of Thl7cells in the pathogenesis of chronic hepatitis B and its aggravation.Methods:32CHB patients,44HBV-related ACLF patients and20healthy controls were involved in our research. Besides, liver tissues were obtained from10CHB patients,6ACLF patients and6liver donors during liver biopsy and liver transplantations. Serum biochemical parameters, coagulation function parameters and serum viral load of HBV DNA were determined. The frequencies of circulating Th17cells and interleukin17(IL-17) mRNA expressions in peripheral blood mononuclear cells (PBMCs) were detected by flow cytometry and quantitative real-time polymerase chain reaction respectively. Immunohistochemical staining was performed to demonstrate the expressions of IL-17+cells in the liver tissues. The serum IL-17concentrations were determined by enzyme-linked immunosorbent assays, and their dynamic changes in different prognostic ACLF patients were also observed. We also explored the relationships between the peripheral Th17cells frequencies and the serum alanine transaminase (ALT) levels, the serum HBV DNA loads and the model of end-stage liver disease (MELD) scores.Results:1Alteration of circulating Th17cells frequencies A total of32patients with CHB,44patients with HBV-related ACLF (23early-stage patients and21medium-stage and end-stage patients) and20normal controls received peripheral Thl7cells (CD3+CD8-IL17+T cells) frequencies detection. The frequencies of circulating Th17cells in CHB group (1.47±0.60)%, ACLF group (3.20±1.08)%were all significantly higher than that in control group (0.86±0.43)%,(all P<0.001), and the circulating Th17cells frequencies in ACLF group were significantly higher than that in CHB group (P<0.001). Moreover, medium-stage and end-stage ACLF patients (3.78±1.04)%had a significantly higher circulating Th17cell frequency than early-stage patients (2.68±0.82)%,(P<0.001).2Variation of IL-17mRNA expressions in PBMCsA total of17patients with CHB,15patients with HBV-related ACLF and17normal controls received IL-17mRNA expressions in PBMCs detection. The relative quantitative expressions of IL-17mRNA in control group were set to1.00, IL-17mRNA expressions were4.32±1.77and18.32±8.21in CHB and ACLF group compared with control group respectively. There was significant difference between each group (all P<0.001). IL-17mRNA expressions were higher in ACLF group than the other two, and control group were the lowest.3Comparison of intrahepatic IL-17+cells of each groupA total of10patients with CHB,6patients with HBV-related ACLF and6normal controls received detection of IL-17+cells expressions in the liver tissues. The frequencies of IL-17+cells were (10.6±4.8/hpf),(21.1±6.6/hpf) and (0.5±0.2/hpf), in CHB, ACLF patients and normal controls respectively. There was significant difference between each group (P<0.05or P<0.01). The frequency of IL-17+cells in ACLF group was higher than the other two, and control group was the lowest.4Change of serum IL-17levelsA total of32patients with CHB,44patients with HBV-related ACLF (23early-stage patients and21medium-stage and end-stage patients) and20normal controls received serum IL-17levels detection. Serum IL-17levels in CHB group (15.88±6.51pg/ml), ACLF group (35.03±11.54pg/ml) were higher than that in control group (10.04±4.06pg/ml, P<0.05, P<0.001, respectively), and the levels of serum IL-17in ACLF group were significantly higher than that in CHB group (P<0.001). In addition, medium-stage and end-stage ACLF patients (41.13±12.19pg/ml) had a higher serum IL-17level than early-stage patients (29.46±7.56pg/ml, P<0.01).5Correlation of circulating Th17cells frequencies with laboratory parameters and MELD scoreIn CHB patients, the frequencies of circulating Th17cells were positively associated with serum alanine transaminase (ALT) levels (r=0.51, P<0.01), but no correlation was found between circulating Th17cells frequencies and serum HBV DNA loads. The peripheral Th17cells frequencies were positively correlated with international normalized ratio (INR)(r=0.44, P<0.01) and MELD sore (r=0.44, P<0.01) in ACLF patients. However, there was no correlation between circulating Th17cells frequencies and serum HBV DNA loads or ALT levels.6Kinetic changes of serum IL-17levels in different prognostic ACLF patientsA total of22ACLF patients with medical treatment received dynamic serum IL-17levels detection. According to the outcomes of28-day observation, the patients were divided into survival group (n=8) and non-survival group (n=14). The survival patients (30.40±8.08pg/ml) had an initially lower serum IL-17level compared with the non-survivors (40.45±7.92pg/ml, P<0.05), and the serum IL-17level showed a decreasing trend on day7(26.03±6.55pg/ml),14(24.88±8.58pg/ml),21(20.86±6.37pg/ml) and28(15.02±5.59pg/ml). In contrast, the non-survival group exhibited an increasing trend on day7(42.90±10.24pg/ml),14(46.82±9.89pg/ml),21(48.79±13.69pg/ml) and28(50.39±5.57pg/ml). And the serum IL-17level in the non-survival group was significantly higher than that in the survival group on day7,14and21(all P<0.001).Conclusions:1The HBV-related ACLF patients and CHB patients showed increased circulating Th17cells frequencies, the serum IL-17levels and intrahepatic IL-17+cells accumulations compared with the normal controls.2Th17cell and IL-17may contribute to liver injury in the pathogenesis of CHB and may promote the occurrence and the development of HBV-related ACLF. The elevated levels of Thl7cells and IL-17may indicate poor short-term prognosis in ACLF patients.3Th17cell may become a new target of treating CHB and ACLF.