Effects of Pegylated Interferon Alpha and Ribavirin (pegIFN-α/RBV) Therapeutic Approach on Regulatory T Cells in HCV-Monoinfected and HCV/HIV-Coinfected Patients.

Approximately 25% of HIV-infected patients are co-infected with HCV. Notably, the burden of HCV infection (e.g., viral persistence, viral load, or HCV-related liver symptoms) is more pronounced in the presence of HIV co-infection. However, to date, the underlying immune mechanisms accounting for accelerated disease progression in HIV/HCV-coinfected individuals have not been described in sufficient detail. We hypothesized that regulatory T cells (Treg) bearing potent immunosuppressive capacities could not only play a substantial role in the pathogenesis of HCV/HIV coinfection but also modulate the response to the standard anti-viral therapy. To this end, we studied alterations in frequencies of Treg cells in correlation with other Treg-related and virus-related parameters in both HCV and HCV/HIV-infected patients subjected to standard pegIFN-α/RBV therapy. Notably, we found that pegIFN-α/RBV therapy significantly increased levels of Treg cells in HCV-infected but not in HIV/HCV-coinfected individuals. Furthermore, HIV/HCV-coinfection was demonstrated to inhibit expansion of regulatory T cells during anti-viral treatment; thus, it might probably be responsible for viral persistence and HCV-related liver damage. Therapy with pegIFN-α/RBV demonstrated a significant effect on regulatory T cells in the course of HIV and/or HCV infection indicating a crucial role in the anti-viral immune response.