No Evidence that Ongoing HIV-Specific Immune Responses Contribute to Persistent Inflammation and Immune Activation in Persons on Long-Term ART

Background. People with HIV (PWH) have persistently elevated levels of inflammation and immune activation despite suppressive antiretroviral therapy (ART), with specific biomarkers showing associations with non-AIDS-defining morbidities and mortality. We investigated the potential role of the HIV-specific adaptive immune response, which also persists under ART, in driving levels of these clinically relevant biomarkers. Methods. HIV-specific T-cell responses and antibody concentrations were measured at study entry in the ACTG A5321 cohort, following a median of 7 years of suppressive ART. HIV persistence measures including cell-associated (CA)-DNA, CA-RNA, and plasma HIV RNA (single-copy assay) were also assessed. Plasma inflammatory biomarkers and T-cell activation and cycling were measured at a pre-ART time point and at study entry. Results. Neither the magnitudes of HIV-specific T-cell responses nor HIV antibody levels were correlated with levels of the inflammatory or immune activation biomarkers, including hs-CRP, IL-6, neopterin, sCD14, sCD163, %CD38+HLA-DR+ CD8+ and CD4+ cells, and %Ki67+ CD8+ and CD4+ cells - including after adjustment for pre-ART biomarker level. Magnitudes of T-cell responses to HIV-Pol were correlated with TNF-α levels, but this was confounded by several factors. Plasma HIV RNA levels were correlated with CD8+ T-cell activation (r = 0.25, p = 0.027), but other HIV persistence parameters were not associated with these biomarkers. In mediation analysis, relationships between HIV persistence parameters and inflammatory biomarkers were not influenced by either HIV-specific T-cell responses or antibody levels. Conclusions. Adaptive HIV-specific immune responses do not appear to contribute to the elevated inflammatory and immune activation profile associated with morbidity and mortality under long-term ART.