Colorectal tissue gene expression in SIV negative and SIV positive Rhesus macaques and sooty mangabeys

In SIV/HIV infection, the gastrointestinal tissue dominates as an important site due to the impact of massive mucosal CD4 depletion and immune activation-induced tissue pathology. Unlike AIDS-susceptible rhesus macaques, natural hosts do not progress to AIDS and resolve immune activation earlier. Here, we examine the role of dendritic cells in mediating immune activation and disease progression. We demonstrate that plasmacytoid dendritic cells (pDC) in the blood upregulate 7-integrin and are rapidly recruited to the colorectum following a pathogenic SIV infection in rhesus macaques. These pDC were capable of producing proinflammatory cytokines and primed a Tc1 response in vitro. Consistent with the upregulation of 7-integrin on pDC, in vivo blockade of 47-integrin dampened pDC recruitment to the colorectum and resulted in reduced immune activation. The upregulation of 7-integrin expression on pDC in the blood was also observed in HIV-infected humans but not in chronically SIV-infected sooty mangabeys that show low levels of immune activation. Our results uncover a new mechanism by which pDC influence immune activation in colorectal tissue following pathogenic immunodeficiency virus infections.

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Kwa S, Kannanganat S, Nigam P, Siddiqui M, Shetty RD, Armstrong W, Ansari A, Bosinger SE, Silvestri G, Amara RR