Human Immunodeficiency Virus–Infected Immunological Nonresponders Have Colon-Restricted Gut Mucosal Immune Dysfunction

BACKGROUND: Human immunodeficiency virus (HIV)–infected immunological nonresponders (INRs) fail to reconstitute their CD4(+) T-cell pool after initiation of antiretroviral therapy, and their prognosis is inferior to that of immunological responders (IRs). A prevailing hypothesis is that the INR phenotype is caused by a persistently disrupted mucosal barrier, but assessments of gut mucosal immunology in different anatomical compartments are scarce. METHODS: We investigated circulating markers of mucosal dysfunction, immune activation, mucosal Th17 and Th22 cells, and mucosa-adherent microbiota signatures in gut mucosal specimens from sigmoid colon and terminal ileum of 19 INRs and 20 IRs in addition to 20 HIV-negative individuals. RESULTS: INRs had higher blood levels of the enterocyte damage marker intestinal fatty acid–binding protein than IRs. In gut mucosal biopsies, INRs had lower fractions of CD4(+) T cells, higher fractions of interleukin 22, and a tendency to higher fractions of interleukin 17–producing CD4(+) T cells. These findings were all restricted to the colon and correlated to circulating markers of enterocyte damage. There were no observed differences in gut microbial composition between INRs and IRs. CONCLUSIONS: Restricted to the colon, enterocyte damage and mucosal immune dysfunction play a role for insufficient immune reconstitution in HIV infection independent of the gut microbiota.