The Dynamic Changes And Regulatory Mechanisms Of CD161~+CD8~+ T Cells In Chronic Hepatitis B Virus Infected Patients

Background:Hepatitis B virus(HBV)infection stimulates specific T cell immune response to promote antiviral immunity,while non-specific systemic inflammation initiated by immune response promotes liver injury,liver fibrosis and liver failure.CD161+CD8+T cells are abundant in liver region and account up to 50%of hepatic T cell,which mainly include mucosal-associated invariant T(MAIT)cells with semi-invariant T cell receptor(TCR)and CD161+CD8+non-MAIT cells with variant TCR.Both MAIT cells and CD161+CD8+nonMAIT cells express CD161 molecule and respond rapidly in an TCR-restricted manner.However,the common and distinct features and functional changes of MAIT cells and CD161+CD8+non-MAIT cells remain unclear in HBV-related liver injury.This limits the exploration of therapeutic or intervention strategy targeting CD161+CD8+T cells.In the current study,dynamic changes in ratio and function of MAIT cells and CD161+CD8+nonMAIT cells as well as related regulatory mechanisms were investigated in different disease phases of chronic hepatitis B(CHB),aiming to lay a foundation for targeting CD161+CD8+T cells to relieve inflammation-mediated liver injury.Methods:In this research,blood and/or liver tissues were collected from healthy donors,chronic HBV infected patients,HBV infection related liver failure patients and liver transplantation patients.The ratio,phenotype and function of CD161+CD8+T cells were tested through flow cytometry,transcriptome-wide analysis,TCR mining and in vitro cell experiments in different CHB phases.Metabolomics profiling of injuried liver and in vitro cell experiments were performed to screen the microenviromental factors,including inflammatory cytokines and bile acid components,related to MAIT cell dysregulation.Results:1.MAIT cells and CD161+CD8+non-MAIT cells were enriched in liver and their ratios change in a different trend in CHB patientsMAIT cells and CD161+CD8+non-MAIT cells were enriched in liver tissue and showed consistently antiviral cytokine secretion and NK cell-like killing ability.MAIT cells decreased while CD161+CD8+non-MAIT cells increased in CHB patients.However,the levels of activation,proliferation and apoptosis in the two subsets from the CHB patients were uniformly up-regulated.2.The increased CD161+CD8+non-MAIT cells in CHB patients were partly derived from CD161-CD8+T cellsTCR signal stimulation could up-regulate the expression of CD161 on the CD161CD8+T cells.CD161+CD8+non-MAIT cells from CHB patients shared same TCR sequence with CD161-CD8+T cells.These results suggested that the increased CD161+CD8+nonMAIT cells in the CHB patients were partly derived from CD161-CD8+T cells.3.Dynamic changes in proportion,phenotype and function of CD161+CD8+non-MAIT cells during CHB progressionThe ratio of CD161+CD8+non-MAIT cells increased with impaired antiviral cytokine secreting ability and elevated granzyme B and IL-17 secreting ability in CHB patients,which were aggravated in liver injury and liver failure patients.Correlation analysis and cell transcriptome signatures revealed that CD161+CD8+non-MAIT cells in CHB patients had pro-inflammatory liver injury potential.4.Dynamic changes in ratio and function of MAIT and related regulatory mechanisms in CHB patients with liver failure and liver transplantationThe ratio of MAIT cells in CHB patients with liver failure was further reduced.Their levels of activation,exhaustion and systemic inflammatory potential increased to a grater extent as compared to those in the patients with compensated liver function.Besides,the antiviral capacity of MAIT cells from liver failure patients was further impaired.liver injury-related bile acid components significantly inhibited the proliferation of MAIT cells and down-regulated their tissue chemotaxis capacity.In patients received liver transplantation,the sufficient recovery of recipient’s MAIT cells indicated better outcome.Conclusion:1.MAIT cells and CD161+CD8+non-MAIT cells are enriched in liver and show elevated antiviral cytokine secretion and NK cell-like killing ability.MAIT cells decrease while CD161+CD8+non-MAIT cells increase in CHB patients.However,they exhibit similarly impaired antiviral capacity,elevated secreting granzyme B and systemic inflammatory capacity,which was related to inflammatory liver injury.These results provide the rationale for targeting CD 161+CD8+T cells to relieve inflammation-mediated liver injury and prevent the liver failure.2.Liver injury-associated bile acid components significantly inhibit the proliferation and tissue chemotaxis capacity of MAIT cells.This suggests the liver injury-related MAIT cell dysregulation and intervention strategy targeting bile acid metabolism.The sufficient recovery of recipient’s MAIT cells indicated better outcome post liver transplantation,indicating that the recovery degree of MAIT cells would be a valuable marker to guide drug selection post transplantation.