Impact of the polarity and the specificity of T lymphocytes on the protection against SARS-CoV-2 infection

La pandémie de COVID-19 causée par le virus SARS-CoV-2 a nécessité une compréhension approfondie de la réponse immunitaire afin de développer des stratégies de prévention et de traitement efficaces. Rapidement, la communauté scientifique a démontré que l'immunité humorale induite par l'infection ou la vaccination était capable de générer des anticorps protecteurs neutralisants contre l'infection et la sévérité de la maladie chez l'homme. Cependant, il a été observé que la protection conférée par ces anticorps diminue rapidement dans le temps, en raison de l'échappement des variants du SARS-CoV-2 aux capacités neutralisantes des anticorps, ainsi qu' à la diminution de leur concentration au fil du temps. Il a également été démontré que la vaccination et l'infection peuvent induire une immunité cellulaire médiée par les lymphocytes T. Cette immunité semble persistée plus longtemps que l'immunité humorale et serait capable de reconnaître plus efficacement les différents variants du SARS-CoV-2. Des résultats expérimentaux chez l'homme et dans des modèles animaux ont suggéré que ce type d'immunité pourrait également jouer un rôle protecteur complémentaire à l'immunité humorale. Cependant, les caractéristiques moléculaires de cette immunité cellulaire protectrice ne sont pas encore bien définies. Cette thèse s'est donc concentrée sur l'impact de la polarité et de la spécificité des lymphocytes T sur la protection contre l'infection par le SARS-CoV-2. Premièrement, nous avons caractérisé de manière extensive la polarité et la spécificité des réponses immunitaires cellulaires spontanées ou induites par l'infection naturelle. Nos résultats ont révélé que la polarité Th1 était associée à une protection contre l'infection. De plus, nous avons identifié les réactivités dirigées contre la zone RBD (Receptor Binding Domain) comme étant les plus importantes dans ces réponses protectrices. Ces résultats ont posé les bases pour le développement d'un test cellulaire permettant de suivre à grande échelle ces réponses immunitaires protectrices. Deuxièmement, nous avons examiné l'effet de la vaccination sur la réponse immunitaire cellulaire. Nous avons confirmé que le nombre de vaccinations était en effet capable de renforcer l'immunité cellulaire dirigée contre la zone RBD. Nous avons identifié les patients atteints de maladies hématologiques malignes comme une population vulnérable chez laquelle la réponse immunitaire cellulaire était altérée malgré la vaccination. Dans cette population, les réponses immunitaires dirigées contre la zone RBD étaient très importantes pour la protection contre l'infection. Nous avons égalexploré l'évolution de la réponse immunitaire au fil du temps et en fonction du nombre de doses de vaccin administrées. Nos analyses ont révélé une diminution des concentrations de l'interféron gamma (IFN-y) avec le temps, jusqu'à atteindre une stabilisation durable, confirmant la longévité des réponses cellulaires. Nous avons également mis en évidence l'échappement du variant Omicron à la protection conférée par la sécrétion d'IFN-y anti-RBD. Cette constatation a souligné le besoin urgent de nouveaux biomarqueurs pour évaluer l'efficacité de la vaccination contre le variant Omicron. Dans ce contexte, nous avons identifié la chimiokine CXCL10 comme un potentiel marqueur d'efficacité vaccinale. En conclusion, cette thèse a contribué à une meilleure compréhension de la réponse immunitaire induite par le SARS-CoV-2 et les vaccins. Les résultats obtenus offrent des outils pour orienter les politiques vaccinales et le développement de nouveaux vaccins. De plus, l'identification de nouveaux biomarqueurs et l'exploration de la polarité et de la spécificité des lymphocytes T ouvrent des perspectives prometteuses pour le développement de vaccins personnalisés. Ces avancées sont cruciales dans la lutte contre la pandémie de COVID-19 et pour se préparer aux futures épidémies virales.The COVID-19 pandemic caused by the SARS-CoV-2 virus has required a deep understanding of the immune response in order to develop effective prevention and treatment strategies. Early on, the scientific community demonstrated that humoral immunity induced by infection or vaccination could generate protective neutralizing antibodies against infection and disease severity in humans. However, it has been shown that the protection mediated by these antibodies diminishes rapidly over time, partly due to the escape of SARS-CoV-2 variants from their acquired neutralizing properties as well as the decrease in their concentration over time. It has also been demonstrated that vaccination and infection can induce cellular immunity mediated by T lymphocytes. This immunity seems to persists longer than humoral immunity and is believed to recognize different variants of SARS-CoV-2 more effectively. Experimental results in humans and animal models have suggested that this type of immunity could also play a complementary protective role to humoral immunity. However, the molecular characteristics of this protective cellular immunity have not yet been fully defined. Therefore, this thesis focused on the impact of the polarity and specificity of T lymphocytes on protection against SARS-CoV-2 infection. Firstly, we extensively characterized the polarity and the specificity of spontaneous or infection-induced cellular immune responses. Our results revealed that Th1 polarity was associated with protection against infection. Furthermore, we identified reactivities directed against the Receptor Binding Domain (RBD) as being most important in these protective responses. These findings laid the foundation for the development of a cellular test to monitor these protective immune responses on a large scale. Secondly, we examined the effect of vaccination on cellular immune response. We confirmed that the number of vaccinations was indeed capable of enhancing cellular immunity directed against RBD. We identified patients with malignant hematologic diseases as a vulnerable population in which cellular immune response was impaired despite vaccination. In this population, immune responses directed against the RBD region were highly significant for protection against infection. We also explored the evolution of the immune response over time and in relation to the number of vaccine doses administered. Our analyses revealed a decrease in interferon-gamma (IFN-y) concentrations over time, reaching a sustained stabilization, confirming the longevity of cellular responses. We also highlighted the evasion of the Omicron variant from the protection conferred by IFN-y secretion against RBD. This finding emphasized the urgent need for new biomarkers to evaluate the effectiveness of vaccination against the Omicron variant. In this context, we identified the chemokine CXCL10 as a potential marker of vaccine efficacy. In conclusion, this thesis has contributed to a better understanding of the immune response induced by SARS-CoV-2 and vaccines. The obtained results provide tools to guide vaccination policies and the development of new vaccines. Moreover, the identification of new biomarkers and the exploration of the polarity and specificity of T lymphocytes offer promising prospects for the development of personalized vaccines. These advancements are crucial in the fight against the COVID-19 pandemic and in preparing for future viral epidemics

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Le Double Cursus Santé Sciences (DCSS) permet de former précocement les futurs acteurs de santé à la recherche. La profonde transformation du système de santé et l’avènement de nouvelles techniques analytiques et numériques ont conduit à reconsidérer la place de la recherche dans la pratique clinique. L’expérience internationale de ce type de programme de formation, notamment aux États-Unis, a révélé le rôle prépondérant que jouent les acteurs de santé ayant acquis une double compétence, médicale et scientifique. En France, un DCSS précoce, pendant les études médicales, a été mis en place dans les années 2000. Cette formation reste cependant disparate et hétérogène, et ne concerne pas toutes les universités. En 2016, l’UFR Santé de Rouen a constaté que le nombre d’étudiants engagés dans ce double cursus était très faible, voire nul selon les années. Aussi, en 2017, un accompagnement institutionnel a été introduit. Celui-ci a abouti à la création d’un tutorat étudiant dédié à cette formation. Il a permis une augmentation du nombre de candidats intéressés et la reconnaissance institutionnelle de ce double parcours. Nous présentons ici les contours de cette formation impliquant étudiants et institution

RBD- specific Th1 responses are associated with vaccine-induced protection against SARS-CoV-2 infection in patients with hematological malignancies

ABSTRACTThe SARS-CoV-2 pandemic still represents a threat for immunosuppressed and hematological malignancy (HM) bearing patients, causing increased morbidity and mortality. Given the low anti-SARSCoV-2 IgG titers post-vaccination, the COVID-19 threat prompted the prophylactic use of engineered anti-SARS-CoV-2 monoclonal antibodies. In addition, potential clinical significance of T cell responses has been overlooked during the first waves of the pandemic, calling for additional in-depth studies. We reported that the polarity and the repertoire of T cell immune responses govern the susceptibility to SARS-CoV-2 infection in health care workers and solid cancer patients. Here, we longitudinally analyzed humoral and cellular immune responses at each BNT162b2 mRNA vaccine injection in 47 HM patients under therapy. Only one-third of HM, mostly multiple myeloma (MM) bearing patients, could mount S1-RBD-specific IgG responses following BNT162b2 mRNA vaccines. This vaccine elicited a S1-RBD-specific Th1 immune response in about 20% patients, mostly in MM and Hodgkin lymphoma, while exacerbating Th2 responses in the 10% cases that presented this recognition pattern at baseline (mostly rituximab-treated patients). Performing a third booster barely improved the percentage of patients developing an S1-RBD-specific Th1 immunity and failed to seroconvert additional HM patients. Finally, 16 patients were infected with SARS-CoV-2, of whom 6 developed a severe infection. Only S1-RBD-specific Th1 responses were associated with protection against SARS-CoV2 infection, while Th2 responses or anti-S1-RBD IgG titers failed to correlate with protection. These findings herald the paramount relevance of vaccine-induced Th1 immune responses in hematological malignancies

Immune responses during COVID-19 infection

International audienceOver the past 16 years, three coronaviruses (CoVs), severe acute respiratory syndrome CoV (SARS-CoV) in 2002, Middle East respiratory syndrome CoV (MERS-CoV) in 2012 and 2015, and SARS-CoV-2 in 2020, have been causing severe and fatal human epidemics. The unpredictability of coronavirus disease-19 (COVID-19) poses a major burden on health care and economic systems across the world. This is caused by the paucity of in-depth knowledge of the risk factors for severe COVID-19, insufficient diagnostic tools for the detection of SARS-CoV-2, as well as the absence of specific and effective drug treatments. While protective humoral and cellular immune responses are usually mounted against these betacoronaviruses, immune responses to SARS-CoV2 sometimes derail towards inflammatory tissue damage, leading to rapid admissions to intensive care units. The lack of knowledge on mechanisms that tilt the balance between these two opposite outcomes poses major threats to many ongoing clinical trials dealing with immunostimulatory or immunoregulatory therapeutics. This review will discuss innate and cognate immune responses underlying protective or deleterious immune reactions against these pathogenic coronaviruses

Serum soluble MAdCAM-1: A new biomarker for cancer immunotherapy.

International audienc

Guidelines for DC preparation and flow cytometry analysis of mouse nonlymphoid tissues

This article is part of the Dendritic Cell Guidelines article series, which provides a collection of state-of-the-art protocols for the preparation, phenotype analysis by flow cytometry, generation, fluorescence microscopy and functional characterization of mouse and human dendritic cells (DC) from lymphoid organs and various nonlymphoid tissues. DC are sentinels of the immune system present in almost every mammalian organ. Since they represent a rare cell population, DC need to be extracted from organs with protocols that are specifically developed for each tissue. This article provides detailed protocols for the preparation of single-cell suspensions from various mouse nonlymphoid tissues, including skin, intestine, lung, kidney, mammary glands, oral mucosa and transplantable tumors. Furthermore, our guidelines include comprehensive protocols for multiplex flow cytometry analysis of DC subsets and feature top tricks for their proper discrimination from other myeloid cells. With this collection, we provide guidelines for in-depth analysis of DC subsets that will advance our understanding of their respective roles in healthy and diseased tissues. While all protocols were written by experienced scientists who routinely use them in their work, this article was also peer-reviewed by leading experts and approved by all coauthors, making it an essential resource for basic and clinical DC immunologists

Cancer Induces a Stress Ileopathy Depending on β-Adrenergic Receptors and Promoting Dysbiosis that Contributes to Carcinogenesis

International audienceAbstract Gut dysbiosis has been associated with intestinal and extraintestinal malignancies, but whether and how carcinogenesis drives compositional shifts of the microbiome to its own benefit remains an open conundrum. Here, we show that malignant processes can cause ileal mucosa atrophy, with villous microvascular constriction associated with dominance of sympathetic over cholinergic signaling. The rapid onset of tumorigenesis induced a burst of REG3γ release by ileal cells, and transient epithelial barrier permeability that culminated in overt and long-lasting dysbiosis dominated by Gram-positive Clostridium species. Pharmacologic blockade of β-adrenergic receptors or genetic deficiency in Adrb2 gene, vancomycin, or cohousing of tumor bearers with tumor-free littermates prevented cancer-induced ileopathy, eventually slowing tumor growth kinetics. Patients with cancer harbor distinct hallmarks of this stress ileopathy dominated by Clostridium species. Hence, stress ileopathy is a corollary disease of extraintestinal malignancies requiring specific therapies. Significance: Whether gut dysbiosis promotes tumorigenesis and how it controls tumor progression remain open questions. We show that 50% of transplantable extraintestinal malignancies triggered a β-adrenergic receptor–dependent ileal mucosa atrophy, associated with increased gut permeability, sustained Clostridium spp.–related dysbiosis, and cancer growth. Vancomycin or propranolol prevented cancer-associated stress ileopathy. This article is highlighted in the In This Issue feature, p. 87

Cancer Induces a Stress Ileopathy Depending on beta-Adrenergic Receptors and Promoting Dysbiosis that Contributes to Carcinogenesis

Gut dysbiosis has been associated with intestinal and extraintestinal malignancies, but whether and how carcinogenesis drives compositional shifts of the microbiome to its own benefit remains an open conundrum. Here, we show that malignant processes can cause ileal mucosa atrophy, with villous microvascular constriction associated with dominance of sympathetic over cholinergic signaling. The rapid onset of tumorigenesis induced a burst of REG3γ release by ileal cells, and transient epithelial barrier permeability that culminated in overt and long-lasting dysbiosis dominated by Gram-positive Clostridium species. Pharmacologic blockade of β-adrenergic receptors or genetic deficiency in Adrb2 gene, vancomycin, or cohousing of tumor bearers with tumor-free lit-termates prevented cancer-induced ileopathy, eventually slowing tumor growth kinetics. Patients with cancer harbor distinct hallmarks of this stress ileopathy dominated by Clostridium species. Hence, stress ileopathy is a corollary disease of extraintestinal malignancies requiring specific therapies. SIGNIFICANCE: Whether gut dysbiosis promotes tumorigenesis and how it controls tumor progression remain open questions. We show that 50% of transplantable extraintestinal malignancies triggered a β-adrenergic receptor–dependent ileal mucosa atrophy, associated with increased gut permeability, sustained Clostridium spp.–related dysbiosis, and cancer growth. Vancomycin or propranolol prevented cancer-associated stress ileopathy

The Polarity and Specificity of Antiviral T Lymphocyte Responses Determine Susceptibility to SARS-CoV-2 Infection in Patients with Cancer and Healthy Individuals

International audienceAbstract Vaccination against coronavirus disease 2019 (COVID-19) relies on the in-depth understanding of protective immune responses to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). We characterized the polarity and specificity of memory T cells directed against SARS-CoV-2 viral lysates and peptides to determine correlates with spontaneous, virus-elicited, or vaccine-induced protection against COVID-19 in disease-free and cancer-bearing individuals. A disbalance between type 1 and 2 cytokine release was associated with high susceptibility to COVID-19. Individuals susceptible to infection exhibited a specific deficit in the T helper 1/T cytotoxic 1 (Th1/Tc1) peptide repertoire affecting the receptor binding domain of the spike protein (S1-RBD), a hotspot of viral mutations. Current vaccines triggered Th1/Tc1 responses in only a fraction of all subject categories, more effectively against the original sequence of S1-RBD than that from viral variants. We speculate that the next generation of vaccines should elicit Th1/Tc1 T-cell responses against the S1-RBD domain of emerging viral variants. Significance: This study prospectively analyzed virus-specific T-cell correlates of protection against COVID-19 in healthy and cancer-bearing individuals. A disbalance between Th1/Th2 recall responses conferred susceptibility to COVID-19 in both populations, coinciding with selective defects in Th1 recognition of the receptor binding domain of spike. See related commentary by McGary and Vardhana, p. 892. This article is highlighted in the In This Issue feature, p. 87