Youngblood, B. | Search bioRxiv

bioRxiv2021

HIV-specific CD8 T cells from elite controllers have an epigenetic imprint that preserves effector functions

Several lines of evidence support a central role for CD8 T cells as key determinants in the control of HIV, particularly in rare "elite controllers" who control the virus to undetectable levels in the blood in the absence of antiretroviral therapy (ART). While HIV-specific CD8 T cells isolated from elite controllers have enhanced antiviral cytokine production and proliferative capacity in response to antigen stimulation when compared to cells isolated from viremic or even aviremic ART-suppressed non-controllers, the cell-intrinsic mechanisms underlying the enhanced T cell memory-like function of HIV-specific CD8 T cells in elite controllers remain largely undefined. To identify the transcriptional and epigenetic pathways that regulate functional capacity in HIV-specific CD8 T cells in elite controllers, we performed genome-wide transcriptional and DNA methylation analysis of MHC Class I multimer+ CD8 T cells sorted from aviremic elite controllers compared to aviremic non-controllers on suppressive ART. Co-omics analysis revealed enrichment for gene signatures that support a multipotent differentiation state, cell survival, and a long-lived effector cell fate in HIV-specific CD8 T cells from elite controllers. Specifically, we observed DNA methylation programs at the transcription factor binding sites of the stem-associated factors TCF-1 and LEF1 that delineate HIV-specific CD8 T cells from elite controllers versus ART-treated individuals. HIV-specific CD8 T cells in elite controllers also maintain T cell receptor and IL-12/STAT4 pathway signaling and have suppressed pro-apoptotic TNF pathway signaling. These findings show that HIV-specific CD8 T cells from elite controllers have enhanced expression and DNA methylation programs that maintain developmental potential and in turn promote long-term survival, proliferative potential, and effector capacity. These data also provide new insights into the relationship between stem-associated transcription factors and stable epigenetic restriction of T cell developmental capacity.

immunology↗

bioRxiv2020

IL-12 signaling promotes TET2-mediated DNA demethylation during CD8 T cell effector differentiation

CD8 T cell memory differentiation endows T cells with an ability to rapidly induce effector functions upon pathogen re-encounter. While it is well established that substantial epigenetic remodeling occurs during the effector stage of the immune response, the signaling events that imprint CD8 T cells with these stable epigenetic programs are not well-defined. To gain insight into the signaling determinants of effector-associated epigenetic programming among CD8 T cells, we explored the role of IL-12 in the imprinting of IFNg expression during human CD8 T cell priming. We observed that TCR-mediated stimulation of human naive CD8 T cells is not sufficient to induce substantial demethylation of the IFNg promotor. However, TCR stimulation in the presence of the inflammatory cytokine, IL-12, resulted in significant and stable demethylation of the IFNg locus that was commensurate with an increase in IFNg expression. We further show that IL-12-associated demethylation of the IFNg locus is coupled to cell division through TET2-dependent passive demethylation in an ex vivo human CAR T cell model system and an in vivo immunologically competent murine system. Collectively, these data illustrate that IL-12 signaling promotes TET2-mediated effector epigenetic programming in CD8 T cells during the primary immune response and serve as proof of concept that signal 3 cytokines can be used to guide the induction of epigenetically regulated traits among T cells used for adoptive immunotherapies.

immunology↗