IL2, IFN γ, and TNF α Promoters in Virus-Specific CD8 + T Cells from Feline Immunodeficiency Virus Infected Cats

摘要

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. Furthermore, 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 , TNF α, and IFN γ 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 postinfection and decreased TNFα at week 4 postinfection 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 postinfection. Finally, we documented Foxp3 binding to the IL2 , TNF α, and IFN γ promoters at 8 weeks and 6 months postinfection in virus-specific CD8~(+) T cells following Treg cell coculture. In summary, the results here clearly demonstrate that Foxp3 inhibits IL2 , TNF α, and IFN γ 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.