Which molecular mechanism allows XCR1+ DCs to activate killer lymphocytes during antiviral and antitumoral responses

Les cellules dendritiques (DC) sont les sentinelles de l'organisme. Elles sont constituées de plusieurs sous-populations, chacune possédant des caractéristiques et fonctions propres. Les DC conventionnelles de type 1 (cDC1) sont l'une de ces sous-populations. Ces cellules sont identifiables dans tous les tissus, et quelle que soit l'espèce par l'expression d'un marqueur unique: le récepteur de chimiokine XCR1 (Crozat et al. 2010;2011). Les cDC1 possèdent des fonctions uniques qui promeuvent l'activation des lymphocytes, notamment via la présentation croisée d'antigènes exogènes (Cancel et al. 2019). Hormis la présentation croisée, les mécanismes régissant les interactions entre cDC1 et lymphocytes restent encore mal caractérisés. L'objectif de ma thèse était de déterminer les voies de signalisation permettant aux cDC1 de dialoguer avec les lymphocytes, à l'homéostasie, lors d'infections ou en contexte tumoral. J'ai identifié plusieurs signaux jouant un rôle dans ce dialogue: la production par les cDC1 de CXCL9 possédant des propriétés attractrices des lymphocytes T, la transprésentation par les cDC1 d'IL-15 en complexe avec l'IL15Rα régulant l'homéostasie des lymphocytes, et enfin le récepteur de chimiokine XCR1 participant à l'attraction des cDC1 par les lymphocytes sécrétant son ligand XCL1 (Yoshida et al. 1998). D'autre part, j'ai aussi montré que selon les chimiokine présentes dans la tumeur, les cDC1 pouvaient être bénéfiques ou délétères pour l'hôte. Ma thèse pose les bases de nouvelles perspectives thérapeutiques visant à utiliser les propriétés des cDC1 comme compléments aux immunothérapies actuellement utilisées en clinique chez des patients atteints de cancers.Dendritic cells (DC) are the body's sentinels. DCs are composed of several sub-populations, each of which has its own characteristics and functions. Conventional Type 1 DCs (cDC1) represent one of these sub-populations. These cells are identifiable in all tissues, regardless of species, by the expression of a unique marker: the XCR1 chemokine receptor (Crozat et al. 2010; 2011). cDC1 have a range of unique functions that promote lymphocyte activation, including the cross presentation of exogenous antigens (Cancel et al. 2019). Apart from cross presentation, the mechanisms governing interactions between cDC1 and lymphocytes are still poorly characterized. The objective of my thesis was to determine the signaling pathways that allow cDC1 to interact with lymphocytes, at homeostasis, during infections or in a tumor context. I have identified several signals that play a role in this dialogue: the production by cDC1 of CXCL9, a chemokine with T cell attracting properties, the transpresentation by cDC1 of IL-15 in complex with IL15Rα regulating lymphocyte homeostasis, and finally the XCR1 chemokine receptor involved in attracting cDC1 by lymphocytes secreting XCL1, its ligand (Yoshida et al. 1998). On the other hand, I have also shown that depending on the chemotactic molecules present in the tumor, cDC1 may be beneficial or harmful to the host. My thesis work lays the foundation for new therapeutic perspectives to use cDC1 properties as a complement to immunotherapies currently used in clinical practice in patients with cancers

Table_1_Are Conventional Type 1 Dendritic Cells Critical for Protective Antitumor Immunity and How?.docx

<p>Dendritic cells (DCs) are endowed with a unique potency to prime T cells, as well as to orchestrate their expansion, functional polarization and effector activity in non-lymphoid tissues or in their draining lymph nodes. The concept of harnessing DC immunogenicity to induce protective responses in cancer patients was put forward about 25 years ago and has led to a multitude of DC-based vaccine trials. However, until very recently, objective clinical responses were below expectations. Conventional type 1 DCs (cDC1) excel in the activation of cytotoxic lymphocytes including CD8⁺ T cells (CTLs), natural killer (NK) cells, and NKT cells, which are all critical effector cell types in antitumor immunity. Efforts to investigate whether cDC1 might orchestrate immune defenses against cancer are ongoing, thanks to the recent blossoming of tools allowing their manipulation in vivo. Here we are reporting on these studies. We discuss the mouse models used to genetically deplete or manipulate cDC1, and their main caveats. We present current knowledge on the role of cDC1 in the spontaneous immune rejection of tumors engrafted in syngeneic mouse recipients, as a surrogate model to cancer immunosurveillance, and how this process is promoted by type I interferon (IFN-I) effects on cDC1. We also discuss cDC1 implication in promoting the protective effects of immunotherapies in mouse preclinical models, especially for adoptive cell transfer (ACT) and immune checkpoint blockers (ICB). We elaborate on how to improve this process by in vivo reprogramming of certain cDC1 functions with off-the-shelf compounds. We also summarize and discuss basic research and clinical data supporting the hypothesis that the protective antitumor functions of cDC1 inferred from mouse preclinical models are conserved in humans. This analysis supports potential applicability to cancer patients of the cDC1-targeting adjuvant immunotherapies showing promising results in mouse models. Nonetheless, further investigations on cDC1 and their implications in anti-cancer mechanisms are needed to determine whether they are the missing key that will ultimately help switching cold tumors into therapeutically responsive hot tumors, and how precisely they mediate their protective effects.</p

NK cells orchestrate splenic cDC1 migration to potentiate antiviral protective CD8+ T cell responses

A successful immune response relies on a tightly regulated delivery of the right signals to the right cells at the right time. Here we show that innate and innate-like lymphocytes use two mechanisms to orchestrate in time and space the functions of conventional type 1 dendritic cells (cDC1) in spleen. Early after murine cytomegalovirus infection, XCL1 production by lymphocytes with innate functions attracts red pulp cDC1 near IFN-γ-producing NK cells, generating superclusters around infected cells in the marginal zone. There, cDC1 and NK cells physically interact reinforcing their reciprocal activation. Targeted IL-12 delivery and IL-15/IL-15Rα transpresentation by cDC1 trigger NK cell activation and expansion. In return, activated NK cells deliver GM-CSF to cDC1, triggering their CCR7-dependent relocalization into the T cell zone. This NK cell-dependent licensing of cDC1 accelerates the priming of virus-specific CD8 + T cells. Our findings reveal a novel mechanism through which cDC1 bridge innate and adaptive immunity

Natural killer cells and dendritic epidermal γδ T cells orchestrate type 1 conventional DC spatiotemporal repositioning toward CD8+ T cells

International audienceSuccessful immune responses rely on a regulated delivery of the right signals to the right cells at the right time. Here we show that natural killer (NK) and dendritic epidermal γδ T cells (DETCs) use similar mechanisms to spatiotemporally orchestrate conventional type 1 dendritic cell (cDC1) functions in the spleen, skin, and its draining lymph nodes (dLNs). Upon MCMV infection in the spleen, cDC1 clusterize with activated NK cells in marginal zones. This XCR1-dependent repositioning of cDC1 toward NK cells allows contact delivery of IL-12 and IL-15/IL-15Rα by cDC1, which is critical for NK cell responses. NK cells deliver granulocyte-macrophage colony-stimulating factor (GM-CSF) to cDC1, guiding their CCR7-dependent relocalization into the T cell zone. In MCMV-infected skin, XCL1-secreting DETCs promote cDC1 migration from the skin to the dLNs. This XCR1-dependent licensing of cDC1 both in the spleen and skin accelerates antiviral CD8+ T cell responses, revealing an additional mechanism through which cDC1 bridge innate and adaptive immunity

Type 1 conventional dendritic cells and interferons are required for spontaneous CD4 + and CD8 + T‐cell protective responses to breast cancer

International audienceObjectives. To better understand how immune responses may be harnessed against breast cancer, we investigated which immune cell types and signalling pathways are required for spontaneous control of a mouse model of mammary adenocarcinoma. Methods. The NOP23 mammary adenocarcinoma cell line expressing epitopes derived from the ovalbumin model antigen is spontaneously controlled when orthotopically engrafted in syngeneic C57BL/6 mice. We combined this breast cancer model with antibodymediated depletion of lymphocytes and with mutant mice affected in interferon (IFN) or type 1 conventional dendritic cell (cDC1) responses. We monitored tumor growth and immune infiltration including the activation of cognate ovalbumin-specific T cells. Results. Breast cancer immunosurveillance required cDC1, NK/NK T cells, conventional CD4 + T cells and CD8 + cytotoxic T lymphocytes (CTLs). cDC1 were required constitutively, but especially during Tcell priming. In tumors, cDC1 were interacting simultaneously with CD4 + T cells and tumor-specific CTLs. cDC1 expression of the XCR1 chemokine receptor and of the T-cell-attracting or T-cell-activating cytokines CXCL9, IL-12 and IL-15 was dispensable for tumor rejection, whereas IFN responses were necessary, including cDC1intrinsic signalling by STAT1 and IFN-γ but not type I IFN (IFN-I). cDC1 and IFNs promoted CD4 + and CD8 + T-cell infiltration, terminal differentiation and effector functions. In breast cancer patients, high intratumor expression of genes specific to cDC1, CTLs, CD4 + T cells or IFN responses is associated with a better prognosis. Conclusion. Interferons and cDC1 are critical for breast cancer immunosurveillance. IFN-γ plays a prominent role over IFN-I in licensing cDC1 for efficient T-cell activation

Analysis of Heritability and Shared Heritability Based on Genome-Wide Association Studies for Thirteen Cancer Types

BACKGROUND: Studies of related individuals have consistently demonstrated notable familial aggregation of cancer. We aim to estimate the heritability and genetic correlation attributable to the additive effects of common single-nucleotide polymorphisms (SNPs) for cancer at 13 anatomical sites. METHODS: Between 2007 and 2014, the US National Cancer Institute has generated data from genome-wide association studies (GWAS) for 49 492 cancer case patients and 34 131 control patients. We apply novel mixed model methodology (GCTA) to this GWAS data to estimate the heritability of individual cancers, as well as the proportion of heritability attributable to cigarette smoking in smoking-related cancers, and the genetic correlation between pairs of cancers. RESULTS: GWAS heritability was statistically significant at nearly all sites, with the estimates of array-based heritability, hl (2), on the liability threshold (LT) scale ranging from 0.05 to 0.38. Estimating the combined heritability of multiple smoking characteristics, we calculate that at least 24% (95% confidence interval [CI] = 14% to 37%) and 7% (95% CI = 4% to 11%) of the heritability for lung and bladder cancer, respectively, can be attributed to genetic determinants of smoking. Most pairs of cancers studied did not show evidence of strong genetic correlation. We found only four pairs of cancers with marginally statistically significant correlations, specifically kidney and testes (ρ = 0.73, SE = 0.28), diffuse large B-cell lymphoma (DLBCL) and pediatric osteosarcoma (ρ = 0.53, SE = 0.21), DLBCL and chronic lymphocytic leukemia (CLL) (ρ = 0.51, SE =0.18), and bladder and lung (ρ = 0.35, SE = 0.14). Correlation analysis also indicates that the genetic architecture of lung cancer differs between a smoking population of European ancestry and a nonsmoking Asian population, allowing for the possibility that the genetic etiology for the same disease can vary by population and environmental exposures. CONCLUSION: Our results provide important insights into the genetic architecture of cancers and suggest new avenues for investigation

Analysis of Heritability and Shared Heritability Based on Genome-Wide Association Studies for Thirteen Cancer Types

BACKGROUND: Studies of related individuals have consistently demonstrated notable familial aggregation of cancer. We aim to estimate the heritability and genetic correlation attributable to the additive effects of common single-nucleotide polymorphisms (SNPs) for cancer at 13 anatomical sites. METHODS: Between 2007 and 2014, the US National Cancer Institute has generated data from genome-wide association studies (GWAS) for 49 492 cancer case patients and 34 131 control patients. We apply novel mixed model methodology (GCTA) to this GWAS data to estimate the heritability of individual cancers, as well as the proportion of heritability attributable to cigarette smoking in smoking-related cancers, and the genetic correlation between pairs of cancers. RESULTS: GWAS heritability was statistically significant at nearly all sites, with the estimates of array-based heritability, hl (2), on the liability threshold (LT) scale ranging from 0.05 to 0.38. Estimating the combined heritability of multiple smoking characteristics, we calculate that at least 24% (95% confidence interval [CI] = 14% to 37%) and 7% (95% CI = 4% to 11%) of the heritability for lung and bladder cancer, respectively, can be attributed to genetic determinants of smoking. Most pairs of cancers studied did not show evidence of strong genetic correlation. We found only four pairs of cancers with marginally statistically significant correlations, specifically kidney and testes (ρ = 0.73, SE = 0.28), diffuse large B-cell lymphoma (DLBCL) and pediatric osteosarcoma (ρ = 0.53, SE = 0.21), DLBCL and chronic lymphocytic leukemia (CLL) (ρ = 0.51, SE =0.18), and bladder and lung (ρ = 0.35, SE = 0.14). Correlation analysis also indicates that the genetic architecture of lung cancer differs between a smoking population of European ancestry and a nonsmoking Asian population, allowing for the possibility that the genetic etiology for the same disease can vary by population and environmental exposures. CONCLUSION: Our results provide important insights into the genetic architecture of cancers and suggest new avenues for investigation

Analysis of heritability and shared heritability based on genome-wide association studies for 13 cancer types

Background: Studies of related individuals have consistently demonstrated notable familial aggregation of cancer. We aim to estimate the heritability and genetic correlation attributable to the additive effects of common single-nucleotide polymorphisms (SNPs) for cancer at 13 anatomical sites. Methods: Between 2007 and 2014, the US National Cancer Institute has generated data from genome-wide association studies (GWAS) for 49 492 cancer case patients and 34 131 control patients. We apply novel mixed model methodology (GCTA) to this GWAS data to estimate the heritability of individual cancers, as well as the proportion of heritability attributable to cigarette smoking in smoking-related cancers, and the genetic correlation between pairs of cancers. Results: GWAS heritability was statistically significant at nearly all sites, with the estimates of array-based heritability, hl², on the liability threshold (LT) scale ranging from 0.05 to 0.38. Estimating the combined heritability of multiple smoking characteristics, we calculate that at least 24% (95% confidence interval [CI] = 14% to 37%) and 7% (95% CI = 4% to 11%) of the heritability for lung and bladder cancer, respectively, can be attributed to genetic determinants of smoking. Most pairs of cancers studied did not show evidence of strong genetic correlation. We found only four pairs of cancers with marginally statistically significant correlations, specifically kidney and testes (ρ = 0.73, SE = 0.28), diffuse large B-cell lymphoma (DLBCL) and pediatric osteosarcoma (ρ = 0.53, SE = 0.21), DLBCL and chronic lymphocytic leukemia (CLL) (ρ = 0.51, SE =0.18), and bladder and lung (ρ = 0.35, SE = 0.14). Correlation analysis also indicates that the genetic architecture of lung cancer differs between a smoking population of European ancestry and a nonsmoking Asian population, allowing for the possibility that the genetic etiology for the same disease can vary by population and environmental exposures. Conclusion: Our results provide important insights into the genetic architecture of cancers and suggest new avenues for investigation.11 page(s

Analysis of Heritability and Shared Heritability Based on Genome-Wide Association Studies for 13 Cancer Types

Background: Studies of related individuals have consistently demonstrated notable familial aggregation of cancer. We aim to estimate the heritability and genetic correlation attributable to the additive effects of common single-nucleotide polymorphisms (SNPs) for cancer at 13 anatomical sites. Methods: Between 2007 and 2014, the US National Cancer Institute has generated data from genome-wide association studies (GWAS) for 49 492 cancer case patients and 34 131 control patients. We apply novel mixed model methodology (GCTA) to this GWAS data to estimate the heritability of individual cancers, as well as the proportion of heritability attributable to cigarette smoking in smoking-related cancers, and the genetic correlation between pairs of cancers. Results: GWAS heritability was statistically significant at nearly all sites, with the estimates of array-based heritability, h(l)(2), on the liability threshold (LT) scale ranging from 0.05 to 0.38. Estimating the combined heritability of multiple smoking characteristics, we calculate that at least 24% (95% confidence interval [CI] = 14% to 37%) and 7% (95% CI = 4% to 11%) of the heritability for lung and bladder cancer, respectively, can be attributed to genetic determinants of smoking. Most pairs of cancers studied did not show evidence of strong genetic correlation. We found only four pairs of cancers with marginally statistically significant correlations, specifically kidney and testes (rho = 0.73, SE = 0.28), diffuse large B-cell lymphoma (DLBCL) and pediatric osteosarcoma (rho = 0.53, SE = 0.21), DLBCL and chronic lymphocytic leukemia (CLL) (rho = 0.51, SE = 0.18), and bladder and lung (rho = 0.35, SE = 0.14). Correlation analysis also indicates that the genetic architecture of lung cancer differs between a smoking population of European ancestry and a nonsmoking Asian population, allowing for the possibility that the genetic etiology for the same disease can vary by population and environmental exposures. Conclusion: Our results provide important insights into the genetic architecture of cancers and suggest new avenues for investigation