AIDS research and human retroviruses 2017 10 17() doi 10.1089/AID.2017.0187
Polyfunctional CD8+ T cells play a critical role in controlling viremia during AIDS lentiviral infections. However, for most HIV infected individuals, virus-specific CD8+ T cells exhibit loss of polyfunctionality including loss of IL2, TNFα, and IFNγ. Using the feline immunodeficiency virus (FIV) model for AIDS lentiviral persistence, our laboratory has demonstrated that FIV-activated Treg cells target CD8+ T cells, leading to a reduction in IL2 and IFNγ production. Further, we have demonstrated that Treg cells induce expression of the repressive transcription factor, Foxp3 in CD8+ T cells. Based upon these findings, we asked if Treg-induced Foxp3 could bind to the IL2, TNFα, and IFNγ promoter regions in virus-specific CD8+ T cells. Following coculture with autologous Treg cells, we demonstrated decreased mRNA levels of IL2 and IFNγ at weeks 4 and 8 post-infection and decreased TNFα at week 4 post infection in virus-specific CD8+ T cells. We also clearly demonstrated Treg cell induced Foxp3 expression in virus-specific CD8+ T cells at weeks 1, 4, and 8 post-infection. Finally, we documented Foxp3 binding to the IL2, TNFα and IFNγ promoters at 8 weeks and 6 months post-infection in virus-specific CD8+ T cells following Treg cell coculture. In summary, the results here clearly demonstrate that Foxp3 inhibits IL2, TNFα and IFNγ transcription by binding to their promoter regions in lentivirus-specific CD8+ T cells. We believe this is the first description of this process during the course of AIDS lentiviral infection.