TRM and mucosal tissue sites are protected from age-associated phenotypic changes in secondary lymphoid organs

Abstract

Abstract The persistence and maintenance of immunological memory is critical for long-term immunity generated in response to infection and vaccination. Aging of memory T cells in humans has predominantly been studied in the peripheral blood, and considerably less is known about the aging of memory T cells within tissues. Using tissues obtained from human organ donors, we investigated how tissue localization, expression of the CD103 integrin, and age influence the phenotype of tissue resident memory T cells (TRM). Using multi-parameter flow cytometry, we characterized diverse tissue sites from donors ages 9 to 93 years old and demonstrate that age-associated changes in the T cell compartment exhibit tissue- and subset- specific dynamics. CD8 T cells in blood-rich tissues spleen and lung have elevated expression of replicative senescence markers CD57 and KLRG1 relative to lung-associated lymph nodes (LLN), jejunum, and mesenteric lymph nodes (MLN). CD103+ TRM have the lowest expression of CD57 and KLRG1 across all tissue sites relative to both CD103− TRM and circulating TEM. CD8 T cells in lymphoid tissues spleen, LLN, and MLN exhibit the largest age-associated increases in expression of CD57, KLRG1, CD244, and PD-1. Together, these results demonstrate that age-associated phenotypic changes are most prominent in secondary lymphoid organs, while TRM and mucosal sites exhibit few senescent changes. Supported by the National Science Foundation (NSF) Graduate Research Fellowship Program (GRFP) and grants from NIH (P01 AI106697, U19 AI057266)