Project description:Inhibitory proteins, such as programmed cell death protein 1 (PD-1), have been extensively studied in peripheral T cell responses to foreign, self, and neoantigens. Notably, these proteins are first expressed during T cell development in the thymus. Reports suggest that PD-1 limits regulatory T cell (Treg) development, but the mechanism by which PD-1 exerts this function remains unknown. The present study expands the evaluation of PD-1 and its ligands in the thymus, demonstrating that some of the highest expressers of PD-1 and PD-L1 are agonist selected cells. Surprisingly, we reveal a selective role for PD-1 in regulating the developmental niche only for Tregs as other agonist selected cell populations, such as natural killer T cells, remain unchanged. We also ruled out PD-1 as a regulator of proliferation or cell death of agonist selected Tregs and further demonstrated that PD-1 deficient Tregs have reduced TCR signaling. Unexpectedly, the data suggests that PD-1 deficient thymocytes produce elevated levels of IL-2, a Treg niche limiting cytokine. Collectively, these data suggest a novel role for PD-1 in regulating IL-2 production and the concurrent agonist selection of thymic Tregs. This observation has implications for the use of checkpoint blockade in the context of cancer and infection.
Project description:Severe infection commonly results in T cell aging, which leads to impaired pathogen clearance or increased secondary infection in both humans and animals. However, the exact mechanisms remain poorly understood. Here, we demonstrated that severe infection-induced IL-33 production resulted in acute thymic involution-mediated naive T cell aging and impaired host control of infection in mouse disease models of schistosomiasis or sepsis. Furthermore, we illustrated that IL-33 triggered excessive generation of medullary thymic epithelial cell (mTEC) IV (thymic tuft cells) in a Pou2f3-dependent manner, as a consequence, disturbed mTEC/cortical TEC (cTEC) compartment and caused acute thymic involution during severe infection. More importantly, IL-33 deficiency or IL-33 receptor ST2 deficient thymus transplantation rescued T-cell immunity to better control infection in mice. Our findings not only uncover a novel link between severe infection-induced IL-33 and thymic involution-mediated naive T cell aging, but also suggest that targeting IL-33 or ST2 is a promising strategy to rejuvenate T cell immunity to better control severe infection.
Project description:The current model of hematopoiesis only resolves the thymus around the production and establishment of the peripheral T cell pool. However, the role and in situ development of other immune subsets has been overlooked. We aim to demonstrate that during TL1A and IL-18 induced inflammation, the thymus is capable of producing other cell types such as neutrophils, monocytes, and macrophages and that these potentially have other functions aside from supporting T cell development as scavengers. Here we have proven that ex vivo and in vivo treatment with TL1A and IL-18 results in acute thymic atrophy by a massive loss of DP T cells and shrinking of the thymic lobe. By electron microscopy, flow cytometry and single cell we demonstrate that neutrophils are able to maturate inside the thymus lobe in a NOTCH-independent manner. We used fate-mapping tools to elucidate the origin of thymic neutrophils since we observed a great expansion in our culture that is isolated from the influx of BM progenitors. The Rag1-Cre Rosa26-YFP fate mapping model revealed that neutrophils share a common progenitor with T cells, while monocytes/macrophages do not. Furthermore, we found that most of the thymic GMPs (defined as Lin-Sca-1-c-Kit+CD16/32+CD34+) show history of Rag1 expression in comparison with bone marrow GMPs. Additionally, by using Ms4a3-Cre Rosa26Tdtomato fate mapping model we observed that there was not difference in Tdt labeling between the thymus and bone marrow, suggesting that thymic neutrophils still undergo conventional neutrophils pathway arising from GMPs. Moreover, we show that thymic-derived neutrophils are functional and are capable of forming extracellular neutrophils traps (NETs) similarly to benchmark peritoneal neutrophils. We found that the expansion of thymic neutrophils is GM-CSF dependent by using Csf2rb KO mice. Additionally, we identified DR3+ and IL-18Rα+ expressing subsets of ILCs and gdT cells as the cellular source GM-CSF. Lastly, in vivo treatment with TL1A+IL-18 lead to emergency granulopoiesis and an increase of neutrophils in all the organs investigated, including the thymus.
Project description:Background & Aims: The liver is one of the organs most commonly affected by metastasis. The presence of liver metastasis is reported to be responsible for an immunosuppressive microenvironment and diminished immunotherapy efficacy. Here, we aimed to investigate the role of IL-10 in liver metastasis formation and decipher its therapeutic potential in affecting immunotherapy effectiveness. Methods: To induce spontaneous or forced liver metastasis in mice, murine cancer cells (MC38) or colon tumor organoids were injected into the cecum or the spleen, respectively. Mice with complete and cell-type specific deletion of IL-10- and IL-10Ra were used to identify the source and the target of IL-10 during metastasis formation. Programmed death ligand 1 (PD-L1)-deficient mice were used to test the role of this checkpoint. Flow cytometry was applied to characterize the regulation of IL-10 on PD-L1. Results: We found that Il10-deficient mice and mice treated with IL-10Ra antibodies were protected against liver metastasis formation. Furthermore, by using IL-10 reporter mice, we demonstrated that Foxp3+ regulatory T cells (Tregs) were the major cellular source of IL-10 in liver metastatic sites. Accordingly, deletion of IL-10 in Tregs, but not in myeloid cells, led to reduced liver metastasis. Mechanistically, IL-10 acted on Tregs in an autocrine manner, thereby further amplifying IL-10 production. Furthermore, IL-10 acted on myeloid cells, i.e., monocytes, and induced the upregulation of the immune checkpoint protein PD-L1. Finally, the PD-L1/PD-1 axis attenuated CD8-dependent cytotoxicity against metastatic lesions. Conclusions: Treg-derived IL-10 upregulates PD-L1 expression in monocytes, which in turn reduces CD8+ T-cell infiltration and related antitumor immunity in the context of colorectal cancer (CRC)-derived liver metastasis. These findings provide the basis for future monitoring and targeting of IL-10 in CRC-derived liver metastasis.
Project description:The goal is to identify an IL-22Fc specific gene signature in human intestinal epithelial cells in order to support PD biomarkers for IL-22Fc. We have identified IL-22Fc specific activity in HT-29 cells as secreted acute phase proteins only in the presence of IL-1β. Therefore, HT-29 cells (from gCell) will be cultured with IL-22, IL-1β, IL-6 (as a pSTAT3 activation control) as well as IL-22 + IL-1β and IL-6 + IL-1β. The "SAMID" sample characteristic is a sample identifier internal to Genentech. The ID of this project in Genentech's ExpressionPlot database is PRJ0027983 Keywords: Expression profiling by array
Project description:TOX is a member of the HMG-Box transcription factors and plays important roles in thymic T cell development. Outside of the thymus, however, TOX is also highly expressed by CD8 and CD4 T cells in various states of activation and in settings of cancer and autoimmune disease. In CD4 T cells, TOX has been primarily studied in T follicular helper (TFH) cells where it , along with TOX2 promotes TFH differentiation by regulating key TFH-associated genes and suppressing CD4 cytotoxic T cell differentiation. However, the role of TOX in other Th cell subtypes is less clear. In our study, we show that TOX is expressed in several physiologically-activated Th subtypes and its ectopic expression modestly enhances the in vitro differentiation of Th2 and Treg cells. TOX overexpression also induced the expression of a small number of genes in unpolarized Th cells involved in cell activation (Pdcd1, PD-1), cellular trafficking (Ccl3, Ccl4, Xcl1) and in suppressing inflammation (Il10) that was conserved in multiple Th subtypes. We additionally show that TOX co-occupies these genes with the transcription factor BATF and that TOX-induced expression of IL-10, but not PD-1, is BATF-dependent. Based on these data, we propose a model where TOX regulates Th cell chemotactic genes involved in facilitating dendritic cell-T cell interactions and aids in the resolution or prevention of inflammation through the production of IL-10.
Project description:IL-2R signaling is essential for regulatory T cell (Treg) function. However, the precise contribution for IL-2 during Treg thymic development, peripheral homeostasis, and lineage stability remains unclear. Here we show that IL-2R signaling is essential for thymic Tregs at an early step for expansion/survival and a later step for functional maturation. Using selective deletion of CD25 in peripheral Tregs, we also find that IL-2R signaling was absolutely essential for their persistence whereas Treg lineage stability was IL-2-independent. CD25 knockout peripheral Tregs showed increased apoptosis, oxidative stress, signs of mitochondrial dysfunction, and reduced transcription of key enzymes of lipid and cholesterol biosynthetic pathways. A divergent IL-2 transcriptional signature was noted for thymic Tregs versus peripheral Tregs. These data indicate that IL-2R signaling in the thymus and the periphery leads to distinctive effects on Treg function, where peripheral Treg survival depends on a non-conventional mechanism of metabolic regulation.