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.