GC Tfh Cell Metabolism and Survival of HIV-1 Infection

Abstract CD4 T cells are the primary targets for HIV-1 infection and their loss is a hallmark of HIV-1 disease. However, T follicular helper (Tfh) cells, a distinct subset of CD4 T cells that are specialized in helping B cells form germinal centers (GCs) for the generation of high-affinity class-switched antibodies, undergo expansion in people living with HIV-1 (PLHIV). Indeed, Tfh cells with latent HIV-1 are enriched in PLHIV, whether the PLHIV are on antiretroviral therapy (ART) or not. This shows that Tfh cells are preferentially infected by HIV-1 and are able to survive infection. Through total RNAseq of tonsillar subsets of T cells, including Tfh cells, our lab was able to find a sharp upregulation of an inhibitor of apoptosis family member gene (BIRC5) and a distinct metabolic gene profile in Tfhs compared to the other subsets. We further were able to find and confirm that (1) BIRC5 was highly expressed in human tonsil Tfh cells and the expression was upregulated upon HIV-1 infection, (2) human tonsil Tfh cells had high levels of Fatty Acid Oxidation related genes, but low levels of glycolytic genes, when compared with non-Tfh CD4 T cells, and (3) inhibition of FaO and BIRC5 led to changes in the survival of Tfh cells following HIV-1 infection. Our results show that Tfh survival of HIV-1 is associated with both the metabolic profile and expression of BIRC5 due to their ability to inhibit virus-induced direct and bystander apoptosis. Supported by grants from the NIH T32: Immunology and Infectious Disease Training Program