Tryptophan Catabolism. Progressive HIV infection is characterized by dysregulation of the intestinal immune barrier, translocation of immunostimulatory microbial products, and chronic systemic inflammation that is thought to drive progression of disease to AIDS. Elements of this pathologic process persist despite viral suppression during highly active antiretroviral therapy (HAART), and drivers of these phenomena remain poorly understood. Using high-resolution bacterial community profiling, we identified a dysbiotic mucosal-adherent community enriched in Proteobacteria and depleted of Bacteroidia members that was associated with markers of mucosal immune
disruption, T cell activation, and chronic inflammation in HIV-infected subjects. These observations demonstrate a link between mucosal-adherent colonic bacteria and immunopathogenesis during
progressive HIV infection that is apparent even in the setting of viral suppression during HAART.