Modifications of T-lymphocyte subsets before and during interferon and ribavirin treatment for chronic hepatitis C infection

T-cell homeostasis in chronic HCV-infected patients treated with interferon and ribavirin or an interferon-free regimen

Direct-acting antiviral has replaced pegylated interferon-α and ribavirin-based treatment in the treatment of chronic hepatitis C virus (HCV) infection. While interferon-α is immune modulating and causes lymphopenia, interferon-free regimens seem to be well-tolerated. This study aimed to compare T-cell homeostasis before, during, and after HCV treatment with or without interferon-α in patients with chronic HCV infection. A total of 20 patients with chronic HCV infection were treated with pegylated interferon-α and ribavirin, and six patients were treated with an interferon-free regimen. All patients were treated for a minimum of 12 weeks. Interferon-α treatment caused an increase in the density of the receptor for IL-7 (IL-7Rα) during treatment, while interferon-free regimens caused a decrease in IL-7Rα density. After a sustained viral response, proportions of IL-7Rα+ T cells and IL-7Rα density decreased compared to prior treatment values. Finally, a proportion of CD8+ effector memory was lower while proportion of apoptotic T cells was higher after sustained virologic response compared to prior treatment. Despite lymphopenia during interferon, alterations in T-cell homeostasis during treatment were relatively similar in patients receiving interferon-based treatment and in patients receiving interferon-free treatment, and alterations during and after treatment seem to illustrate a reduced need for high levels of T cells aimed at controlling infection.

Could a loss of memory T cells limit responses to hepatitis C virus (HCV) antigens in blood leucocytes from patients chronically infected with HCV before and during pegylated interferon-alpha and ribavirin therapy?

The proportions and activation status of T cells may influence responses to hepatitis C virus (HCV) and treatment outcome in patients receiving pegylated interferon (IFN)-alpha/ribavirin therapy. We confirmed that IFN-gamma enzyme-linked immunospot (ELISPOT) responses to HCV are poor in HCV patients and showed that responses to HCV and cytomegalovirus (CMV) antigens decrease during therapy. This was most apparent in patients with sustained virological response (SVR). Baseline frequencies of CD4+ effector memory (TEM) T cells were lower in SVR than non-SVR. Proportions of CD4+ and CD8+ TEM and terminally differentiated effector memory (TEMRA) T cells declined on therapy in SVR, as did proportions of Fas+ CD8+ TEMRA T cells. Baseline frequencies of programmed death (PD)-1-expressing CD4+ TEM and TEMRA T-cells were higher in SVR. Therapy increased percentages of PD-1+ CD4+ central memory (TCM) T cells and PD-1+ CD8+ TEM and TEMRA T cells in SVR. We conclude that successful therapy depletes circulating antigen-specific CD4+ T cell responses. This paralleled decreases in proportions of effector memory T cells and higher percentages of CD4+ TCM T cells expressing PD-1.