Influence of the Notch signaling pathway on CD8⁺T lymphocyte function in patients with chronic hepatitis C

Objective To investigate the influence of the Notch signaling pathway on CD8+T lymphocyte function in patients with chronic hepatitis C (CHC) and the role of the Notch signaling pathway in the pathogenesis of CHC.Methods A total of 38 treatment-na6 ve CHC patients who visited Shaanxi Provincial People's Hospital from January to August, 2016 and 17 healthy volunteers were enrolled in this study.CD8+T lymphocytes were isolated, and quantitative real-time PCR was used to measure the mRNA expression of Notch1 and Notch2 in CD8+T lymphocytes.CD8+T lymphocytes, which were isolated from HLA-A2-restricted CHC patients, were co-cultured with hepatitis C virus (HCV) -infected Huh7.5 cells in both direct and indirect contact culture systems.DAPT, a Notch signaling pathway inhibitor, was added, and the changes in cytotoxic and non-cytotoxic functions of CD8+T lymphocytes were analyzed by measuring the levels of lactate dehydrogenase level and cytokines.The t-test was used for comparison of continuous data between groups.Results The mRNA expression of Notch1 and Notch2 in CD8+T lymphocytes in CHC patients was 10 and 4 times, respectively, that in healthy volunteers (t = 6.63, P = 0.003; t = 18.88, P < 0.001) .Inhibition of the Notch signaling pathway significantly increased the percentage of dead cells in the direct contact culture system (26.41 ± 4.76% vs 13.65 ± 4.65%, t = 3.32, P = 0.029) , while it did not influence the cytotoxity of CD8+T lymphocytes in the indirect contact culture system.After inhibition of the Notch signaling pathway, there was a significant increase in the expression of interferon-γ in the direct (52.19 ± 12.38 pg/ml vs 18.62 ± 5.66 pg/ml, t = 4.27, P = 0.013) and indirect contact culture systems (18.86 ± 3.09 pg/ml vs 5.52 ± 2.52 pg/ml, t = 5.79, P = 0.004) .After inhibition of the Notch signaling pathway, there was a significant increase in the expression of tumor necrosis factor-α in the direct contact culture system (1296.0 ± 293.3 pg/ml vs 585.3 ± 32.62 pg/ml, t = 4.17, P = 0.014) , while there was no significant change in the indirect contact culture system (297.3 ± 175.4 pg/ml vs 273.7 ± 105.9 pg/ml, t = 0.20, P = 0.851) .Conclusion Inhibition of the Notch signaling pathway can enhance the cytotoxic and non-cytotoxic functions of CD8+T lymphocytes in CHC patients.The Notch signaling pathway may induce immune tolerance in chronic HCV infection by inhibiting the function of CD8+T lymphocytes.