Project description:Human skin harbors two major T cell compartments of equal size that are distinguished by expression of the chemokine receptor CCR8. In vitro studies have demonstrated that CCR8 expression is under strict control of T cell antigen receptor (TCR)-engagement and the skin tissue microenvironment. We here examined the relationship between CCR8+ and CCR8− T cells. Phenotypic, functional, and transcriptomic analyses revealed that CCR8+ skin T cells bear all the hallmarks of resident memory T (TRM) cells, including homeostatic proliferation in response to IL-7 and IL-15, surface expression of tissue-localization (CD103) and -retention (CD69) markers, low levels of inhibitory receptors (PD-1, Tim-3, LAG-3), and a lack of senescence markers (CD57, KLRG1). In contrast, CCR8− skin T cells are heterogeneous and comprise variable numbers of exhausted (PD-1+), senescent (CD57+, KLRG1+), and effector (T-bethi, Eomeshi) T cells. Importantly, conventional and high-throughput analyses of expressed T cell receptor beta-chain (TRB) gene rearrangement sequences showed that the two skin memory T cell compartments distinguished by CCR8 expression are clonotypically distinct, suggesting that they are produced in response to separate antigenic challenges and distinct stimulatory conditions. Moreover, the phenotypic profiles of these populations were stable in vitro and the presence of similar levels of telomere erosion excludes the possibility of a linear differentiation pathway. In conclusion, CCR8 marks skin-specific, long-lived memory T cells. Therefore, we propose that CCR8+ T cells should be targeted in future skin vaccination research.
Project description:Comparison of the transcriptional profiles of full-thickness murine skin harboring tissue resident memory T cells exposed to specific or control trigger Expression profiling by high throughput sequencing
Project description:Comparison of the transcriptional profiles of full-thickness murine skin harboring tissue resident memory T cells exposed to specific or control trigger
Project description:Tissue resident memory T cells (TRM) provide superior protection against infection localised to extra-lymphoid compartments in the body. Here we show that CD103+CD8+ TRM cells develop in skin from killer cell lectin-like receptor (KLR)G1-negative precursors that selectively infiltrate the epithelial layer. In the skin, a combination of chemokine-guided epithelial entry, local interleukin (IL)-15 and transforming growth factor (TGF)-β signalling is required for formation and survival of these long-lived memory cells. Importantly, TRM differentiation results in the gradual acquisition of a unique transcriptional profile that differs from that expressed by memory cells in the circulation and other types of skin-resident intra-epithelial T cells, such as the dendritic epidermal T cells (DETC). We provide a comprehensive molecular and developmental framework for the local differentiation of a distinct type of peripheral memory T cell that contributes to an important first-line of immune defence in barrier tissues such as skin and mucosa. 24 samples were analyzed: 3 replicates of memory gB-T CD8+. CD103+ T cells isolated from the skin of C57/BL6 mice on day 30 p.i. with HSV KOS. 3 replicates of memory P14 CD8+ T cells isolated from gut of mice on day 60 p.i. with LCMV Armstrong. 3 replicates of memory gB-T CD8+ T cells from the lung of mice on day 30 p.i. with influenza WSN. 3 replicates of memory CD62L high CD8+ T cells from the spleen of mice on day 30 p.i. with HSV KOS. 3 replicates of memory CD62L low CD8+ T cells from the spleen of mice of day 30 p.i. with HSV KOS. 3 replicates of γδ-DETC isolated from the skin of C57/BL6 mice on day 30 p.i. with HSV KOS. 3 replicates of αβ-DETC from naive TCRδ-/- mice; and 3 replicates of naive gB-T CD8+ T cells from the spleen of naive gB-T transgenic mice.
Project description:Leishmaniasis causes a significant disease burden worldwide. Although Leishmania-infected patients become refractory to reinfection following disease resolution, effective immune protection has not yet been achieved by human vaccines. While circulating Leishmania-specific T cells are known to play a critical role in immunity, the role of memory T cells present in peripheral tissues has not been explored. Here, we identify a population of skin-resident Leishmania-specific memory CD4+ T cells. These cells produce IFNγ, and remain resident in the skin when transplanted by skin graft onto naïve mice. They function to recruit circulating T cells to the skin in a CXCR3 dependent manner, resulting in better control of the parasites. Our findings are the first to demonstrate that CD4+ TRM cells form in response to a parasitic infection, and indicate that optimal protective immunity to Leishmania, and thus the success of a vaccine, may depend on generating both circulating and skin-resident memory T cells. Two conditions were analyzed. For each condition, four mice were used, resulting in eight samples in total.
Project description:Tissue resident memory T cells (TRM) provide superior protection against infection localised to extra-lymphoid compartments in the body. Here we show that CD103+CD8+ TRM cells develop in skin from killer cell lectin-like receptor (KLR)G1-negative precursors that selectively infiltrate the epithelial layer. In the skin, a combination of chemokine-guided epithelial entry, local interleukin (IL)-15 and transforming growth factor (TGF)-β signalling is required for formation and survival of these long-lived memory cells. Importantly, TRM differentiation results in the gradual acquisition of a unique transcriptional profile that differs from that expressed by memory cells in the circulation and other types of skin-resident intra-epithelial T cells, such as the dendritic epidermal T cells (DETC). We provide a comprehensive molecular and developmental framework for the local differentiation of a distinct type of peripheral memory T cell that contributes to an important first-line of immune defence in barrier tissues such as skin and mucosa.
Project description:Memory T cells provide rapid and long-term protection against infection and tumors. The memory CD8+ T cell repertoire contains phenotypically and transcriptionally heterogeneous subsets with specialized functions and recirculation patterns. While these T cell populations have been well characterized in terms of differentiation potential and function, the epigenetic changes underlying memory T cell fate determination and tissue-residency remain largely unexplored. Here, we examined the single-cell chromatin landscape of CD8+ T cells over the course of acute viral infection. We reveal an early bifurcation of memory precursors displaying distinct chromatin accessibility and define epigenetic trajectories that lead to a circulating (TCIRC) or tissue-resident memory T (TRM) cell fate. While TRM cells displayed a conserved epigenetic signature across organs, we demonstrate that these cells exhibit tissue-specific signatures and identify transcription factors that regulate TRM cell populations in a site-specific manner. Moreover, we demonstrate that TRM cells and exhausted T (TEX) cells are distinct epigenetic lineages that are distinguishable early in their differentiation. Together, these findings show that TRM cell development is accompanied by dynamic alterations in chromatin accessibility that direct a unique transcriptional program resulting in a tissue-adapted and functionally distinct T cell state.
Project description:Leishmaniasis causes a significant disease burden worldwide. Although Leishmania-infected patients become refractory to reinfection following disease resolution, effective immune protection has not yet been achieved by human vaccines. While circulating Leishmania-specific T cells are known to play a critical role in immunity, the role of memory T cells present in peripheral tissues has not been explored. Here, we identify a population of skin-resident Leishmania-specific memory CD4+ T cells. These cells produce IFNγ, and remain resident in the skin when transplanted by skin graft onto naïve mice. They function to recruit circulating T cells to the skin in a CXCR3 dependent manner, resulting in better control of the parasites. Our findings are the first to demonstrate that CD4+ TRM cells form in response to a parasitic infection, and indicate that optimal protective immunity to Leishmania, and thus the success of a vaccine, may depend on generating both circulating and skin-resident memory T cells.