PD-1 Involvement in Peripheral Blood CD8+T Lymphocyte Dysfunction in Patients with Acute-on-chronic Liver Failure

Background and Aims:Programmed cell death-1(PD-1)plays an important role in downregulating T lymphocytes but the mechanisms are still poorly understood.This study aimed to explore the role of PD-1 in CD8^(+)T lymphocyte dysfunction in hepatitis B virus(HBV)-related acute-on-chronic liver failure(ACLF).Methods:Thirty patients with HBV-ACLF and 30 healthy controls(HCs)were recruited.The differences in the numbers and functions of CD8^(+)T lymphocytes,PD-1 and glucose transporter-1(Glut1)expression from the peripheral blood of patients with HBV-ACLF and HCs were analyzed.In vitro,the CD8^(+)T lymphocytes from HCs were cultured(HC group)and the CD8^(+)T lymphocytes from ACLF patients were cultured with PD-L1-IgG(ACLF+PD-1 group)or IgG(ACLF group).The numbers and functions of CD8^(+)T lymphocytes,PD-1 expression,glycogen uptake capacity,and Glut1,hexokinase-2(HK2),and pyruvate kinase(PKM2)expression were analyzed among the HC group,ACLF group and ACLF+PD-1group.Results:The absolute numbers of CD8^(+)T lymphocytes in the peripheral blood from patients with HBVACLF were lower than in the HCs(p<0.001).The expression of PD-1 in peripheral blood CD8^(+)T lymphocytes was lower in HCs than in patients with HBV-ACLF(p=0.021).Compared with HCs,PD-1 expression was increased(p=0.021)and Glut1 expression was decreased(p=0.016)in CD8^(+)T lymphocytes from the HBV-ACLF group.In vitro,glycogen uptake and functions of ACLF CD8^(+)T lymphocytes were significantly lower than that in HCs(p=0.017;all p<0.001).When PD-1/PD-L1 was activated,the glycogen uptake rate and expression levels of Glut1,HK2,and PKM2 showed a decreasing trend(ACLF+PD-1 group compared to ACLF group,all p<0.05).The functions of CD8^(+)T lymphocytes in the ACLF+PD-1 group[using biomarkers of Ki67,CD69,IL-2,interferon-gamma,and tumor necrosis factor-alpha-were lower than in the ACLF group(all p<0.05).Conclusions:CD8^(+)T lymphocyte dysfunction is observed in patients with HBV-ACLF.PD-1-induced T lymphocyte dysfunction might involve glycolysis inhibition.