Yu, Z.; Sasidharan-Nair, V.; Bonifacius, A.; Khan, F.; Buchta, T.; Beckstette, M.; Niemz, J.; Hilgendorf, P.; Pietzsch, B.; Mausberg, P.; Keller, A.; Falk, C. S.; Busch, D. S.; Brinkmann, M.; Schober, K.; Cicin-Sain, L.; Mueller, F.; Eiz-Vesper, B.; Floess, S.; Huehn, J.

Epigenetic mechanisms stabilize gene expression patterns during CD8+ T cell differentiation. However, although adoptive transfer of virus-specific T cells is clinically applied to reduce the risk of virus infection or reactivation in immunocompromised individuals, the DNA methylation pattern of virus-specific CD8+ T cells is largely unknown. Hence, we here performed whole-genome bisulfite sequencing of cytomegalovirus-specific human CD8+ T cells and found that they display a unique DNA methylation pattern consisting of 79 differentially methylated regions when compared to bulk memory CD8+ T cells. Among them was TBKBP1, coding for TBK-binding protein 1 that can interact with TANK-binding kinase 1 (TBK1) and mediate pro-inflammatory responses in innate immune cells downstream of intracellular virus sensing. Since TBKBP1 has not yet been reported in T cells, we aimed to unravel its role in virus-specific CD8+ T cells. TBKBP1 demethylation in terminal effector CD8+ T cells correlated with TBKBP1 expression and was stable upon long-term in vitro culture. TBKBP1 overexpression resulted in enhanced TBK1 phosphorylation upon stimulation of CD8+ T cells and significantly improved their virus neutralization capacity. Collectively, our data demonstrate that TBKBP1 modulates virus-specific CD8+ T cell responses and could be exploited as therapeutic target to improve adoptive T cell therapies.