Immune Targeting of PD-1hi Expressing Cells During and Alter Antiretroviral Therapy in SIV-infected Rhesus Macaques

摘要

High-level T-cell expression of PD-1 during SIV infection is correlated with impaired proliferation and function. We evaluated the phenotype and distribution of T-cells and Tregs during antiretroviral therapy plus PD-1 modulation (using a B7-DC-Ig fusion protein) and post-ART. Chronically SIV-infected rhesus macaques received: 11 wk of ART (Group A); 11 wk of ART plus B7-DC-Ig (Group B); 11 wk of ART plus B7-DC-Ig, then 12 wk of B7-DC-Ig alone (Group C). Continuous B7-DC-Ig treatment (group C) decreased rebound viremia post-ART compared to pre-ART levels, associated with decreased PD-1^hi expressing T-cells and Tregs in PBMCs, and PD-1^hi Tregs in lymph nodes. It transiently decreased expression of Ki67 and α4β7 in PBMC CD4⁺ and CD8⁺ Tregs for up to 8 wk post-ART and maintained Ag-specific T-cell responses at low levels. Continued immune modulation targeting PD-1^hi cells during and post-ART helps maintain lower viremia, keeps a favorable T-cell/Treg repertoire and modulates antigen-specific responses.