Abstract Text: People living with HIV (PLWH) experience chronic inflammation, which contributes to co-morbidities in virally-suppressed HIV+ individuals. HIV-1-infected macrophages constitute important mediators of chronic innate immune activation. Additive effects of aging and persistent HIV-1 infection can promote macrophage dysfunction, contributing to chronic inflammation, referred to as “inflammaging”. We had previously reported that nuclear export and cytoplasmic expression of HIV-1 intron-containing RNA (icRNA) activates MAVS-dependent innate immune sensing and persistent type I IFN responses in macrophages. However, signaling pathways downstream of icRNA sensing have not been fully elucidated. In this study, we investigate whether selective dysregulation of HIV-1 icRNA sensing pathways in aged macrophages can lead to chronic innate immune activation. We utilized patient derived monocyte-derived macrophages (MDMs) from young ( < 35 years old) and aged (>50 years old) donors, and observed significantly higher induction of inflammatory responses upon HIV-1 infection and icRNA-expression in older (>50 yo) MDMs (IP-10 expression was enhanced 4-fold). Interestingly, knock-down of IRF5 expression, but not IRF3 or IRF7, all of which are phosphorylated and translocated to the nucleus upon MAVS activation, in THP1/PMA macrophages and MDMs, robustly attenuated icRNA-induced IP-10 secretion. Furthermore, knockdown of IRF5-associated ubiquitin ligase TRAF6 decreased IRF5 nuclear localization and icRNA-induced IP-10 production. In contrast, establishment of HIV-1 infection in macrophages induced nuclear localization of IRF5 that further perpetuated IRF5-mediated inflammatory cytokine expression. Studies in progress will address whether IRF5 expression or activation is dysregulated in HIV-infected aged macrophages and contributes to the “inflammaging” phenotype observed in aging HIV+ individuals.
