Project description:The function of MR1-restricted mucosal-associated invariant T (MAIT) cells in tumor immunity is unclear. Here we show that MAIT cell-deficient mice have enhanced NK cell-dependent control of metastatic B16F10 tumor growth relative to control mice. Analyses of this interplay in human tumor samples reveal that high expression of a MAIT cell gene signature negatively impacts the prognostic significance of NK cells. Paradoxically, pre-pulsing tumors with MAIT cell antigens, or activating MAIT cells in vivo, enhances anti-tumor immunity in B16F10 and E0771 mouse tumor models, including in the context of established metastasis. These effects are associated with enhanced NK cell responses and increased expression of both IFN-γ-dependent and inflammatory genes in NK cells. Importantly, activated human MAIT cells also promote the function of NK cells isolated from patient tumor samples. Our results thus describe an activation-dependent, MAIT cell-mediated regulation of NK cells, and suggest a potential therapeutic avenue for cancer treatment.
Project description:To show the similarity among MAIT-iPSCs, hiPSCs and hESCs and the gradual change of global gene expression of reMAIT cells along with differentiation, this experiment was designed. MAIT cells, MAIT-iPSCs, hiPSCs, hESCs, MAIT cells, and reMAIT cells at the several differerent stages of differentiation were collected. Then, they were applied in this experiment.
Project description:MAIT cells (MAITs) represent an abundant T lymphocyte subset with unique specificity for microbial metabolites presented by the MHC-1b molecule, MR1. MAIT conservation along evolution indicates important, non-redundant functions, but their low frequency in mice has hampered their detailed characterization. Here, we performed a transcriptomic analysis of murine MAITs in comparison with NKT subsets and with mainstream T cells in spleen and peripheral organs of B6-MAIT/CAST mice expressing a Rorc-GFP transgene. MAIT and NKT cells have been FACS-sorted after tetramer staining (MR1:5-OP-RU Tet+ for MAIT, CD1d:PBS57Tet+ for NKT), and 1/17 subsetting based on the expression of Rorc.
Project description:Natural killer (NK) cells are primarily responsible for tumor surveillance, and their activation entirely depends on optimal metabolic signals. The adaptation of NK cell anti-tumor responses to nutritional stress is still poorly understood. Here, based on single-cell RNA sequencing, we discovered that dietary restriction (DR) enriches the rejuvenated subset of CD27+CD11b+ NK cells and improves their activation via Eomesodermin (Eomes), a transcription factor upregulated during DR treatment. Eomes reverses the differentiation of rejuvenated to senescent NK cells by antagonizing the T-bet-Zeb2 axis while improving chemotaxis and adhesion. Furthermore, DR increases the chromatin accessibility of Eomes to genes that regulate chemotaxis and adhesion in NK cells. To summarize, tumor control under dietary restriction requires Eomes-regulated NK cell anti-tumor immunity.
Project description:N6-methyladenosine (m6A) is the most prevalent post-transcriptional modification on RNA. NK cells are the predominant innate lymphoid cells that mediate anti-viral and anti-tumor immunity. However, whether and how m6A modifications affect NK cell immunity remains unknown. Here, we discover that YTHDF2, a well-known m6A reader, is upregulated in NK cells upon activation by cytokines, tumors, and cytomegalovirus infection. Ythdf2 deficiency in NK cells impairs NK cell anti-tumor and anti-viral activity in vivo. YTHDF2 maintains NK cell homeostasis and terminal maturation, correlating with modulating NK cell trafficking and regulating Eomes, respectively. YTHDF2 promotes NK cell effector function and is required for IL-15-mediated NK cell survival and proliferation by forming a STAT5-YTHDF2 positive feedback loop. Transcriptome-wide screening identifies Tardbp to be involved in cell proliferation or survival as a YTHDF2-binding target in NK cells. Collectively, we elucidate the biological roles of m6A modifications in NK cells and highlight a new direction to harness NK cell anti-tumor immunity.
Project description:The tumor microenvironment (TME) harbors numerous types of cellular stress that can activate Heat Shock Factor 1 (HSF1), a central regulator of stress response. HSF1 has been shown to directly regulate diverse gene programs beyond the classical heat shock response in a cell-type- and context-specific manner. Here, we uncover significant variability in HSF1 levels and activity between immune populations in patient tumors, with the lowest in natural killer (NK) cells. We demonstrate that accumulation of activated HSF1 in the TME dampens anti-tumor immunity through impairing NK cell cytotoxicity, which could be rescued by NK cells with homeostatic levels of HSF1. HSF1 stabilization results in altered chromatin accessibility and expression of surface receptors and signaling proteins involved in NK cell activation. We further reveal direct occupancy of HSF1 at promoters of genes encoding mediators of NK cell cytotoxicity. Single-cell transcriptional profiling of the TME in the context of elevated HSF1 revealed an inverse relationship between the stress response status and NK cell effector function. Collectively, this work identifies a novel role of HSF1 in regulating the NK cell activation state and subsequent anti-tumor functionality.
Project description:Mucosal-associated invariant T (MAIT) cells recognize bacterial metabolites as antigen and are found in blood and tissues, where they are poised to contribute to barrier immunity. Recent data demonstrate that MAIT cells located in mucosal barrier tissues are functionally distinct from their blood counterparts, but the relationship and circulation of MAIT cells between blood and different tissue compartments remains poorly understood. Previous studies raised the possibility that MAIT cells do not leave tissue and may either be retained or undergo apoptosis. To directly address if human MAIT cells exit tissues, we collected human donor-matched thoracic duct lymph and blood and analyzed MAIT cell phenotype, transcriptome and TCR diversity by RNAseq.