| Background and ObjectivesAfter treatment for chronic Hepatitis B(CHB),a significant decrease in hepatitis B surface antigen(HBsAg)serves as a predictor of functional cure and acts as a surrogate endpoint for CHB cure studies.CHB is an immune-mediated disease,and the host’s immune function is crucial for controlling HBV infection and disease regression.Although studies have indicated that patients with human immunodeficiency virus(HIV)and HBV coinfection have higher HBsAg clearance rates after combination antiretroviral therapy(cART)than patients with HBV mono-infection,studies on the decline of HBsAg in coinfected patients and the underlying immunological mechanisms remain rare.Hence,the present study aims to explore the pattern of HBsAg decline in patients with HIV/HBV coinfection,identify the risk factors,determine its dynamic correlation with other serum markers,and investigate the longitudinal immunological characteristics of HBsAg declining in patients with HIV/HBV coinfection.MethodsIn a longitudinal cohort of HIV/HBV coinfected patients undergoing antiviral therapy,serum biomarkers including HBsAg,HBV pregenomic RNA(pgRNA)and soluble programmed cell death protein 1(sPD-1)were measured.The kinetics of HBsAg decline in coinfected patients were analyzed,and the relationship between other serum biomarkers and HBsAg decline was evaluated.Early HBsAg decline during treatment was associated with sustained antiviral response.In this study,a decline in HBsAg greater than 0.5 log10 IU/mL in six months after initiation of treatment was defined as HBsAg response.Baseline characteristics and longitudinal clinical features of HBsAg response were evaluated.To explore the immunological mechanisms of HBsAg clearance during HIV/HBV coinfection,flow cytometry,ex vivo amplification of specific T cells,enzyme-linked immunosorbent assay(ELISA),and RNA sequencing were used to analyze the immune phenotypic and functional characteristics of HBsAg responders in HIV/HBV coinfection.Results1.HBsAg decline and its relationship with other biomarkers in patients with HIV/HBV coinfection1.1 Fifty-one HIV/HBV coinfected patients were followed up for a median of 59.5(36.0-96.3)months.Five of them achieved HBsAg clearance.No significant difference was found in HBsAg decline between HBeAg-positive and negative patients or between patients with different baseline HBsAg levels.However,patients with a baseline CD4~+T cell count less than 200 cells/mm~3 had a greater decrease in HBsAg(P=0.023).1.2 HBV pgRNA levels were positively correlated with HBsAg levels both before and after treatment in HIV/HBV co-infected patients(Baseline:R=0.6130,P=0.0031;1 year of treatment:R=0.7304,P=0.0021;3 years of treatment:R=0.6970,P=0.0039).1.3 HIV/HBV coinfected patients had higher sPD-1 levels than HBV monoinfected patients,and sPD-1 levels decreased rapidly after treatment(P<0.0001).Baseline sPD-1 levels affected the magnitude of HBsAg decline(P<0.001).1.4 17 patients(33.3%)achieved HBsAg response,defined as a decline greater than 0.5 log10 IU/mL at six months of treatment.Baseline CD4~+T cell count<200 cells/mm3[OR=6.663,95%CI(1.515-29.034),P=0.012]and low baseline sPD-1 levels[OR=5.389,95%CI(1.097-26.464),P=0.038]were associated with HBsAg response.1.5 Compared to patients with HBsAg non-response,patients with HBsAg response had higher rates of abnormal ALT in the early stages of treatment.2.Longitudinal immunological characteristics of patients with HBsAg response in HIV/HBV coinfection2.1 Compared to the HBsAg non-response group,the HBsAg response group had higher levels of HLA-DR,Ki67,PD-1 expression in CD4~+T cells,and higher levels of T-bet and HLA-DR expression in CD8~+T cells,indicating higher levels of T-cell activation,proliferation,and higher functional potential of effector T cells.2.2 After initiation of cART,the HBsAg response group had increased TEM subsets and decreased TEMRA in the memory cell subsets and increased Th17 cell frequency and higher Th17/Treg ratio,presenting characteristics of immune clearance.2.3 Specific T cells were amplified by in vitro peptide fragmentation and measured,and it was found that the IFN-y+CD4~+and IL-2+CD4~+cell were increased in the HBsAg response group during cART.2.4 Correlation analysis revealed that CD4~+HLA-DR+,CD4~+Ki67+,CD4~+PD-1+,CD4~+T-bet+,CD4 TEM,CD8~+CD38+,CD8~+HLA-DR+,CD8~+TIM3+,HBV-specific CD4~+IL-2+,HBV-specific CD4~+IFN-γ+,HBV-specific CD8~+IFN-γ+ levels correlated with HBsAg decline.2.5 RNA sequencing and differentially expressed gene analysis showed that the expression of IL-17 signaling pathway genes and chemokine and inflammatory factor genes were up-regulated in the HBsAg response group.ConclusionHIV/HBV co-infected patients had a high rate of HBsAg seroclearance after initiation of antiretroviral therapy(cART).At 6 months after cART initiation,33.3%of patients had a decrease in HBsAg of more than 0.5 log10 IU/mL(HBsAg response).A lower baseline CD4~+T cell count and sPD-1 level were associated with HBsAg response after treatment,while patients with HBsAg response were more likely to have abnormal ALT levels during treatment.This study also identified that HIV/HBV coinfected patients with HBsAg response had an activated T-cell phenotype and increased proliferation and functional markers,increased frequency of TEM and Th 17 cell populations,enhanced function of HBV-specific CD4~+T-cells secreting IL-2+and IFN-γ+,upregulation of inflammation and chemokine-related gene expression,all of which suggest that patients with rapidly HBsAg decline exhibit features of the immune clearance phase.The correlation analysis showed that the decrease in HBsAg after treatment was mainly related to the activated phenotype and specific secretion function of CD4~+T cells.This study suggests that higher CD4~+T cell activation and secretion function after cART in HIV/HBV co-infected individuals is beneficial for the rapid decline of HBsAg.This provides a new perspective for the design of future research and strategy development towards functional cure of HBV. |
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