Gene expression in the blood of SIV infected Rhesus macaques following in vivo PD-1 blockade

Hyperimmune activation is one of the strong predictors of disease progression during pathogenic immunodeficiency virus infections and is mediated in part by sustained type I interferon (IFN) signaling. Combination antiretroviral therapy suppresses hyperimmune activation only partially in HIV-infected individuals. Here, we show that blockade of Programmed Death-1 (PD-1) during chonic SIV infection significantly reduces the expression of transcripts associated with type I IFN signaling in the blood and colorectal tissue of rhesus macaques (RM). The effect of PD-1 blockade on type I IFN signaling was durable and persisted under high viremia, a condition that is seen in nonprogressive SIV infection in their natural hosts. The reduced type I IFN signaling was associated with enhanced expression of some of the junction-associated genes in the colorectal tissue and a profound decrease in LPS levels in plasma suggesting a possible repair of gut associated junctions and decreased microbial translocation. The reduced type I IFN signaling was also associated with enhanced immunity against gut resident pathogenic bacteria, control of gut associated opportunistic infections and survival of SIV-infected RMs. These results reveal novel mechanisms by which PD-1 blockade enhances survival of SIV-infected RMs and have implications for development of novel therapeutic approaches to control HIV/AIDS.

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Dyavar Shetty R, Velu V, Titanji K, Bosinger SE, Freeman GJ, Silvestri G, Amara RR