Effects of direct-acting antiviral agents on the frequency of myeloid-derived suppressor cells in patients with chronic hepatitis C

Objective To investigate the effects of direct-acting antiviral agents (DAA) therapy on the frequency of myeloid-derived suppressor cells (MDSC) and their subset of monocytic myeloid-derived suppressor cells (M-MDSC) in chronic hepatitis C (CHC) patients. Methods A total of 32 treatment-naive CHC patients and 16 healthy controls were recruited at Third Affiliated Hospital of Sun Yat-Sen University from June 2016 to June 2017. The peripheral blood mononuclear cells (PBMC) were separated from the peripheral blood of patients with CHC before DAA therapy, at four weeks after DAA therapy, at 12 weeks after DAA therapy and 12 weeks after the end of DAA therapy. The frequencies of MDSC and M-MDSC were detected by the flow cytometer. The t test, U test and chi-square test was employed to analyze the data. Results All the 32 treatment-naive patients achieved the rapid virological response and no virological breakthrough was observed. Before DAA therapy, the frequency of MDSC in CHC patients was 2.18%, which was higher than healthy individuals (0.60%; Z=-4.593, P 0.05). However, at 12 weeks after DAA therapy, the MDSC frequency increased, with statically significance compared to the controls (1.64% vs 0.60%, Z=-3.117, P=0.002). At 12 weeks after the end of DAA therapy, the MDSC frequency had decreased to 1.29% again, with no statistical significance compared to the controls (Z=-1.387, P=0.664). The changes of M-MDSC frequency were slightly different. Before DAA therapy, the frequency of M-MDSC in CHC patients was higher compared to healthy controls (1.66% vs 0.81%, Z=-2.745, P 0.05). Conclusion Immune status of the peripheral MDSC and M-MDSC can return to normal after DAA therapy in CHC patients. Key words: Hepatitis C, chronic; Direct-acting antiviral agents; Myeloid-derived suppressor cells; Immunomodulation