Abstract Residual systemic inflammation and mucosal immune dysfunction persist in people living with HIV (PLWH) despite treatment with combined anti-retroviral therapy (cART), but the underlying immune mechanisms are poorly understood. Here we report an altered immune landscape involving upregulation of TLR- and inflammasome signaling, localized CD4 + T cell hyperactivation, and counterintuitively, an enrichment of CD4 + CD25 + FOXP3 + regulatory T cells (T regs ) in the oral mucosa of HIV + patients on therapy. Using human oral tonsil cultures, we found that HIV infection causes an increase in a unique population of FOXP3 + cells expressing PD-1, IFN-γ, Amphiregulin (AREG), and IL-10. These cells persisted even in the presence of the anti-retroviral drug and underwent further expansion driven by TLR-2 ligands and IL-1β. IL-1β also promoted PD-1 upregulation in AKT1 dependent manner. PD-1 stabilized FOXP3 and AREG expression in these cells through a mechanism requiring the activation of Asparaginyl Endopeptidase (AEP). Importantly, these FOXP3 + cells were incapable of suppressing CD4 + T cells in vitro . Concurrently, HIV + patients harbored higher levels of PD-1, IFN-γ, Amphiregulin (AREG), and IL-10 expressing FOXP3 + cells, which strongly correlated with CD4 + T cell hyperactivation, suggesting an absence of CD4 + T cell regulation in the oral mucosa. Taken together, this study provides insights into a novel mechanism of FOXP3 + cell dysregulation and reveals a critical link in the positive feedback loop of oral mucosal immune activation events in HIV + patients on therapy. One Sentence Summary HIV-induced immune dysfunction in lymphoid and mucosal tissues

PD-1 dependent expansion of Amphregulin+FOXP3+ cells is associated with oral immune dysfunction in HIV patients on therapy