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Erythropoietin receptor on cDC1s dictates immune tolerance

ABSTRACT: Type 1 conventional dendritic cells (cDC1s) are unique in their efferocytosis and cross-presenting abilities, resulting in T cell-mediated immunity or tolerance. However, the factors that dictate whether cDC1s induce a tolerogenic or immunogenic response remain largely unknown. Here, we show that the erythropoietin receptor (EpoR) acts as a critical switch that determines the tolerogenic function of cDC1s and the threshold of Ag-specific T cell responses. In total lymphoid irradiation and anti-thymocyte serum (TLI/ATS)-induced allograft tolerance, cDC1s upregulate EpoR expression, and conditional knockout of EpoR in cDC1s diminishes antigen (Ag)-specific FOXP3+ Treg induction and expansion, resulting in allograft rejection. Mechanistically, EpoR promotes efferocytosis-induced tolerogenic maturation of splenic cDC1s towards late-stage CCR7⁺ cDC1s characterized by elevated integrin β8 gene (Itgb8) expression, and conditional knockout of Itgb8 in cDC1s impairs TLI/ATS-induced tolerance. Migratory cDC1s in peripheral lymph nodes preferentially express EpoR, and their capacity to induce FOXP3⁺ Tregs is enhanced by EPO. Reciprocally, EpoR deficiency enables immunogenic maturation of both pLN migratory and splenic CCR7⁺ cDC1s by upregulating genes essential for MHC class II-mediated Ag presentation, cross-presentation and costimulation. Loss of cDC1 EpoR reduces tumor growth by enhancing anti tumor CD8⁺ T cell immunity, particularly by promoting tumor Ag specific CD8⁺ T cell priming in tumor draining lymph nodes to generate more precursor exhausted T cells (Tpex) and by sustaining intratumoral Tpexs while decreasing Tregs. Targeting EpoR on cDC1s to either induce or inhibit immune tolerance could pave the way for novel treatments of a variety of diseases.

ORGANISM(S): Mus musculus

PROVIDER: GSE253056 | GEO | 2024/03/01

REPOSITORIES: GEO

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Project description:Acute and chronic rejection continue to represent serious challenges in transplant medicine. Current medical regimens focus on suppressing T-cell responses, lack effectiveness for some patients and impose significant risks of infection and malignancy. Recent studies have suggested that inhibition of co-stimulation pathways between antigen presenting cells (dendritic cells, macrophages, B-cells) and T-cells may serve as an effective strategy to prevent rejection by promoting allograft tolerance as opposed to simply suppressing immune responses. This concept has garnered excitement across the transplant community and demonstrated promising results in human renal transplant studies. A commonly used approach is inhibition of B7-CD28 and CD40-CD40L costimulatory pathways. Blocking these pathways leads to prolonged allograft survival in fully HLA-mismatched mouse heart transplantation models and non-human primates. There are important gaps in knowledge pertaining to mechanisms by which co-stimulation blockade modulates the recipient immune responses and confers donor organ tolerance. The precise immune cell populations and mechanisms responsible for induction and maintenance of donor organ tolerance remain incompletely understood. We have leveraged single cell RNA sequencing to dissect how traditional immunosuppression (cyclosporine) and co-stimulation blockade (CTLA-4 Ig, anti-CD40L neutralizing antibodies) differentially impact the immune landscape of the transplanted heart using a fully HLA-mismatched mouse model (Balb/c donor heart à B6 recipient). Analysis of these datasets demonstrated striking differences between these treatment regimens. Mice that received co-stimulation blockade displayed a marked increase in the abundance of classical dendritic cells (cDC1s and cDC2s). Compared to the cyclosporine treated group, these cells expressed negative regulators of T-cell stimulation including PDL1. Using recipient mice that lack either cDC1s or cDC2s, we found that cDC1s are absolutely required for co-stimulation blockade to confer long-term allograft survival and prevent recipient immune responses against the transplanted donor heart.

Project description:XCR1+ dendritic cells (DC) have been shown to excel in antigen cross-presentation for the activation of naÃ¯ve CD8 T cells. This property was reported to be associated to the subset of the XCR1+ DC expressing IL-12b upon ex vivo stimulation for 24 h with a mixture of CpG, IFN-Î³, and GM-CSF (Lin ML et al. Proc Natl Acad Sci USA. 2008. PMID: 18272486). DC found in the steady-state non-lymphoid tissues undergo an homeostatic, tolerogenic, maturation and migrate to the draining lymph nodes to interact with naive autoreactive T cells and induction their peripheral tolerance. In contrast, spleen DC are thought to exist solely in an immature state. The aim of this study was to re-examine heterogeneity within steady state spleen XCR1+ DC, in particular examining whether this population encompass a fraction of mature DCs as assessed through their expression of CCR7 and/or the Il12b gene. Indeed, we show that a small fraction of XCR1+ spleen DC constitutively mature into two distinct but likely successive activation stages characterized as CCR7+ and CCR7+Il12b+ respectively, and correlated with increasing ability to cross-present antigen to naÃ¯ve CD8 T cells. Transcriptomic analysis of the subsets of XCR1+ DC found in steady state spleen unexpectedly showed that their homeostatic maturation was unexpectedly associated with up-regulated of many genes thought to drive pro-inflammatory T-cell responses and previously found to be commonly induced upon maturation of distinct DC subsets in response to stimulation by various microbial-type stimuli (Vu Manh TP et al. Eur J Immunol. 2013. PMID: 23553052). Thus, our results reveal that spleen XCR1+ DC undergo constitutive maturation and emphasize the common mechanisms operating upon homeostatic, tolerogenic, DC maturation versus microbial-type stimuli-induced, immunogenic, DC maturation. DC were isolated from the spleen of untreated Il12b-EYFP reporter mice (Reinhardt RL et al. J Immunol. 2006. PMID:16849470) mice as previously described (Robbins SH et al. Genome Biol. 2008. PMID: 18218067; Baranek T et al. Cell Host Microbe. 2012. PMID: 23084923). DC subsets were sorted by flow cytometry according to the marker combinations described in the âcharacteristics: phenotypeâ field for each sample.

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Erythropoietin receptor on cDC1s dictates immune tolerance

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