Project description:We investigated how accumulation of Tregs contributes to T cell dysfunction and clonal constriction of tumor-infiltrating CD8+ T cells. Resected melanoma atissues from tumor-bearing mice were analyzed. The clonal diversity of tumor-associated CD8+ T cells were evaluated by single-cell TCR sequencing respectively, at early or advanced tumor stages or under Treg depletion conditions. TCR-sequencing revealed a clonal shrinkage of tumor-infiltrating CD8+ T cells as tumor progressed, which was associated with reduced survival profile concomitant to increasing Treg proportions.
Project description:TIGIT+ Tregs suppress Th1 and Th17 responses while sparing Th2 responses. Analysis of global gene expression of TIGIT+ vs. TIGIT- Tregs from naive mice reveled that TIGIT+ Tregs display an activated phenotype and are enriched for Treg signature genes including the Treg effector molecule Fgl2 which enables them to selectively spare Th2 responses. TIGIT+ and TIGIT- Tregs were sorted from naïve Foxp3-GFP KI mice (pooled spleen and lymph nodes) TIGIT: T cell immunoreceptor with Ig and ITIM domains
Project description:Regulatory T cells (Tregs) expressing the transcription factor Foxp3 have a pivotal role in maintaining immunological self-tolerance1-5; yet, excessive Treg activities suppress anti-tumor immune responses6-8. Compared to resting phenotype Tregs (rTregs) in the secondary lymphoid organs, Tregs in non-lymphoid tissues including solid tumors exhibit an activated Treg (aTreg) phenotype9-11. However, aTreg function and whether its generation can be manipulated to promote tumor immunity without evoking autoimmunity are largely unexplored. Here we show that the transcription factor Foxo1, previously demonstrated to promote Treg suppression of lymphoproliferative diseases12,13, has an unexpected function in inhibiting aTreg-mediated immune tolerance. We found that aTregs turned over at a slower rate than rTregs, but were not locally maintained in tissues. Transcriptome analysis revealed that aTreg differentiation was associated with repression of Foxo1-dependent gene transcription, concomitant with reduced Foxo1 expression, cytoplasmic Foxo1 localization, and enhanced Foxo1 phosphorylation at sites of the Akt kinase. Treg-specific expression of an Akt-insensitive Foxo1 mutant prevented downregulation of lymphoid organ homing molecules, and impeded Treg homing to non-lymphoid organs, causing CD8+ T cell-mediated autoimmune diseases. Compared to Tregs from healthy tissues, tumor-infiltrating Tregs downregulated Foxo1 target genes more substantially. Expression of the Foxo1 mutant at a lower dose was sufficient to deplete tumor-associated Tregs, activate effector CD8+ T cells, and inhibit tumor growth without inflicting autoimmunity. Thus, Foxo1 inactivation is essential for the migration of aTregs that have a crucial function in suppressing CD8+ T cell responses; and the Foxo signaling pathway in Tregs can be titrated to preferentially break tumor immune tolerance.
Project description:TIGIT+ Tregs suppress Th1 and Th17 responses while sparing Th2 responses. Analysis of global gene expression of TIGIT+ vs. TIGIT- Tregs from naive mice reveled that TIGIT+ Tregs display an activated phenotype and are enriched for Treg signature genes including the Treg effector molecule Fgl2 which enables them to selectively spare Th2 responses.
Project description:Tregs from spleen and thymus of naive Wild-type mice and mice lacking Dendritic Cells (deltaDC) were analyzed. Thymus derived Tregs of both strains show similar expression patterns, peripheral splenic Tregs from deltaDC mice differ from Tregs of WT mice.
Project description:Tumor-draining lymph node (TDLN) invasion by metastatic cells in breast cancer correlates with poor prognosis and is associated with local immunosuppression, which can be partly mediated by regulatory T cells (Tregs). Here, we study Tregs from matched tumor-invaded and non-invaded TDLNs, and breast tumors. We observe that Treg frequencies increase with nodal invasion, that Tregs express higher levels of co-inhibitory/stimulatory receptors than effector cells. Also, while Tregs show conserved suppressive function in TDLN and tumor, conventional T cells (Tconvs) in TDLNs proliferate and produce Th1-inflammatory cytokines, but are dysfunctional in the tumor. We describe a common transcriptomic signature shared by Tregs from tumors and nodes, including CD80, which is significantly associated with poor patient survival. TCR RNA-sequencing analysis indicates trafficking between TDLNs and tumors and ongoing Tconv/Treg conversion. Overall, TDLN Tregs are functional and express a distinct pattern of druggable co-receptors, highlighting their potential as targets for cancer immunotherapy.
Project description:This study aimed to explore the characteristics and role of TNFR2+ Tregs in the microenvironment and progression of gastric cancer by single-cell RNA sequencing.We obtained Tregs from tumor tissues and peripheral blood of three GC patients.Through single-cell RNA sequencing, we found tumor-infiltrating Tregs express high levels of TNFR2. The TNF-a/TNFR2 signaling pathway is activated, accompanied by upregulation of costimulatory molecules. Compared to blood Tregs, tumor-infiltrating Tregs exhibit activated and effector states. In addition to expressing costimulatory molecules such as TNFR2, 4-1BB, OX40 and GITR, tumor-infiltrating Tregs are also characterized by high expression of immune checkpoints such as CTLA-4 and TIGIT and chemokines such as CCR6.This study revealed a high infiltration level of TNFR2+ Tregs with the characteristics of activated and effector Tregs in the tumor microenvironment. Our study provides a new theoretical basis for TNFR2+ Tregs as a therapeutic target in gastric cancer.
Project description:Tumor cells inhibit the anti-tumor immune response by expressing immunomodulatory factors and recruiting immunosuppressive cells to their microenvironment. Regulatory T cells (Tregs) are a population of CD4+ T cells that are commonly found in tumors, promoting a tolerogenic microenvironment and aiding in tumor immune evasion. The immune checkpoint ligand B7x is widely expressed in a broad variety of tumor types and is often associated with greater Treg infiltration, but the mechanism by which B7x promotes tumor-infiltrating Tregs is unknown. Here, we recapitulate the B7x-mediated increase in Tregs in murine tumor models and show that B7x promotes conversion of conventional CD4+ T cells into potently suppressive Tregs. We found that B7x induces global transcriptomic changes in Tregs, driving these cells to adopt an activated and suppressive phenotype. Mechanistically, B7x increased Foxp3 transcriptional expression by modulating the Akt/Foxo signaling pathway. Further, we found that expression of B7x by tumor cells reduced the efficacy of anti-CTLA-4 in syngeneic murine models in a Treg-dependent manner, but this resistance phenotype was overcome by combination anti-B7x and anti-CTLA-4 treatment. Put together, B7x mediates a novel Treg-promoting pathway within tumors and is a promising candidate for combination immunotherapy.