Th17 cells in pathogenic simian immunodeficiency virus infection of macaques

Purpose of review We discuss studies on a subset of CD4(+)T cells, designated Th17, and their role in the pathogenesis of human and simian acquired immune deficiency, caused by infection with HIV and simian immunodeficiency virus (SIV), respectively. Most of the Th17 cells are lost within 2 weeks from infection at mucosal sites of SIV-infected macaques and are not replenished over time. Comparison of simian pathogenic and nonpathogenic models of SIV infection suggests that Th17 cells contribute to the pathogenesis of AIDS. Recent findings Th17 cells, a recently identified subset of T helper cells, play a major role in both inducing autoimmune disorders and fencing off extracellular pathogens. Several groups have reported that the number of Th17 cells is decreased in the gut of HIV-infected and SIV-infected hosts. The loss of Th17 cells from the mucosal compartment has been associated with the dissemination of Salmonella typhimurium that is normally contained locally by the host immune system. It is believed that microbial translocation sustains immune activation in HIV infection and contributes to AIDS. Summary Understanding the mechanisms that lead to disruption of mucosal integrity, viral spread, and chronic immune activation is of crucial importance for the design of efficient vaccines and therapeutic intervention for HIV.