Impact of IgA response on both a novel mucosal vaccine strategy against Salmonella and on adaptive immune response regulation

Les entérobactéries Salmonella sont divisées en plusieurs sérovars dont les quatre principaux Typhimurium, Enteritidis, Typhi et Paratyphi sont responsables soit de gastroentérites soit de fièvres typhoïdes, à raison de plus de 90 millions de cas et 400 000 décès par an. L’apparition de souches multi-résistantes nécessite la mise en place d’une vaccination prophylactique muqueuse. L’environnement intestinal est caractérisé par une balance entre tolérance immunitaire et réaction inflammatoire régulée par les immunoglobulines (Ig) A sécrétoires. Les IgA des sécrétions muqueuses sont dimériques, les IgA sériques sont monomérique et deux isotypes ont été décrits chez l’Homme: IgA1 et IgA2. Nous avons tout d’abord exploré les fonctions des différents isotypes et isoformes des IgA humaines. Nous avons pu noter un rôle anti-inflammatoire des IgA1 à l’inverse d’un rôle pro-inflammatoire des IgA2 et nous avons souligné un processus de régulation de l’expression des récepteurs aux IgA par les IgA elles-mêmes ainsi qu’un axe IgA/lymphocytes T CD8 cytotoxiques. Nous avons ensuite mis en place un vaccin multivalent composé des antigènes SseB et OmpC de Salmonella liés à des Ig sécrétoires. Cette étude a mis en évidence une solide réponse immunitaire humorale et cellulaire spécifique aux antigènes couplés à des IgA ou IgM après vaccination intra-nasale au niveau systémique et muqueux. Par ailleurs, de plus fortes réponses humorales et systémiques spécifiques ont été observées en couplant à la fois OmpC et SseB sur l’IgA. Ce travail de thèse ouvre de nouvelles perspectives pour la mise en place de vaccins muqueux multivalents et pourrait apporter des réponses quant au rôle des IgA.The enterobacteria Salmonella species are divided into several serovars such as Typhimurium, Enteritidis, Typhi and Paratyphi which are the major causative agents of either gastroenteritis or typhoid fever. They are responsible for more than 90 million cases and 400 000 deaths each year. The increase in multi-drug resistant strains requires the implementation of prophylactic mucosal vaccines. Besides, the intestinal environment is characterized by a balance between immune tolerance and inflammatory response tightly regulated by secretory immunoglobulins (Ig) A. Mucosal IgA are mainly dimeric, serum IgA monomeric and two IgA isotypes have been described in humans: IgA1 and IgA2. We firstly explored the functions of the different isotypes and isoforms of human IgA. We pointed out a pro-inflammatory role of IgA2 whereas IgA1 rather oriented the immunity towards an anti-inflammatory response. We have also highlighted both the regulation of IgA receptors expression by IgA and an IgA/CD8 cytotoxic T cells axis. We also designed a multivalent vaccine against Salmonella by coupling two antigens – SseB and OmpC – to secretory Ig. We pointed out solid specific humoral and cellular responses against both these antigens coupled to either IgA or IgM after intra-nasal immunization in mucosal but also systemic compartments. We have also demonstrated the possibility to preserve and increase the antigen immunogenicity with a multivalent vaccine. This thesis thus paves the way for new secretory Ig-vectorized mucosal vaccines. In addition, the immune response could be modulated through the chosen isotype or isoform and the differences in immune activation generated by structural changes in IgA could shed some light on their role in mucosal homeostasis

Impact de la réponse IgA dans une nouvelle stratégie de vaccination muqueuse contre Salmonella et dans la régulation de la réponse adaptative

The enterobacteria Salmonella species are divided into several serovars such as Typhimurium, Enteritidis, Typhi and Paratyphi which are the major causative agents of either gastroenteritis or typhoid fever. They are responsible for more than 90 million cases and 400 000 deaths each year. The increase in multi-drug resistant strains requires the implementation of prophylactic mucosal vaccines. Besides, the intestinal environment is characterized by a balance between immune tolerance and inflammatory response tightly regulated by secretory immunoglobulins (Ig) A. Mucosal IgA are mainly dimeric, serum IgA monomeric and two IgA isotypes have been described in humans: IgA1 and IgA2. We firstly explored the functions of the different isotypes and isoforms of human IgA. We pointed out a pro-inflammatory role of IgA2 whereas IgA1 rather oriented the immunity towards an anti-inflammatory response. We have also highlighted both the regulation of IgA receptors expression by IgA and an IgA/CD8 cytotoxic T cells axis. We also designed a multivalent vaccine against Salmonella by coupling two antigens – SseB and OmpC – to secretory Ig. We pointed out solid specific humoral and cellular responses against both these antigens coupled to either IgA or IgM after intra-nasal immunization in mucosal but also systemic compartments. We have also demonstrated the possibility to preserve and increase the antigen immunogenicity with a multivalent vaccine. This thesis thus paves the way for new secretory Ig-vectorized mucosal vaccines. In addition, the immune response could be modulated through the chosen isotype or isoform and the differences in immune activation generated by structural changes in IgA could shed some light on their role in mucosal homeostasis.Les entérobactéries Salmonella sont divisées en plusieurs sérovars dont les quatre principaux Typhimurium, Enteritidis, Typhi et Paratyphi sont responsables soit de gastroentérites soit de fièvres typhoïdes, à raison de plus de 90 millions de cas et 400 000 décès par an. L’apparition de souches multi-résistantes nécessite la mise en place d’une vaccination prophylactique muqueuse. L’environnement intestinal est caractérisé par une balance entre tolérance immunitaire et réaction inflammatoire régulée par les immunoglobulines (Ig) A sécrétoires. Les IgA des sécrétions muqueuses sont dimériques, les IgA sériques sont monomérique et deux isotypes ont été décrits chez l’Homme: IgA1 et IgA2. Nous avons tout d’abord exploré les fonctions des différents isotypes et isoformes des IgA humaines. Nous avons pu noter un rôle anti-inflammatoire des IgA1 à l’inverse d’un rôle pro-inflammatoire des IgA2 et nous avons souligné un processus de régulation de l’expression des récepteurs aux IgA par les IgA elles-mêmes ainsi qu’un axe IgA/lymphocytes T CD8 cytotoxiques. Nous avons ensuite mis en place un vaccin multivalent composé des antigènes SseB et OmpC de Salmonella liés à des Ig sécrétoires. Cette étude a mis en évidence une solide réponse immunitaire humorale et cellulaire spécifique aux antigènes couplés à des IgA ou IgM après vaccination intra-nasale au niveau systémique et muqueux. Par ailleurs, de plus fortes réponses humorales et systémiques spécifiques ont été observées en couplant à la fois OmpC et SseB sur l’IgA. Ce travail de thèse ouvre de nouvelles perspectives pour la mise en place de vaccins muqueux multivalents et pourrait apporter des réponses quant au rôle des IgA

Impact of IgA isoforms on their ability to activate dendritic cells and to prime T cells

International audienc

Impact of IgA isoforms on their ability to activate dendritic cells and to prime T cells

International audienc

Alteration of microbiota antibody‐mediated immune selection contributes to dysbiosis in inflammatory bowel diseases

International audienceHuman secretory immunoglobulins (SIg) A1 and SIgA2 guide mucosal responses toward tolerance or inflammation, notably through reverse-transcytosis, the apical-to-basal transport of IgA2 immune complexes via M cells of gut Peyer's patches. As such, the maintenance of a diverse gut microbiota requires broad affinity IgA and glycan-glycan interaction. Here, we asked whether IgA1 and IgA2-microbiota interactions might be involved in dysbiosis induction during inflammatory bowel diseases. Using stool HPLC-purified IgA, we show that reverse-transcytosis is abrogated in ulcerative colitis (UC) while it is extended to IgA1 in Crohn's disease (CD). 16S RNA sequencing of IgA-bound microbiota in CD and UC showed distinct IgA1- and IgA2-associated microbiota; the IgA1+ fraction of CD microbiota was notably enriched in beneficial commensals. These features were associated with increased IgA anti-glycan reactivity in CD and an opposite loss of reactivity in UC. Our results highlight previously unknown pathogenic properties of IgA in IBD that could support dysbiosis

Coupling between Myogenesis and Angiogenesis during Skeletal Muscle Regeneration Is Stimulated by Restorative Macrophages

Summary: In skeletal muscle, new functions for vessels have recently emerged beyond oxygen and nutrient supply, through the interactions that vascular cells establish with muscle stem cells. Here, we demonstrate in human and mouse that endothelial cells (ECs) and myogenic progenitor cells (MPCs) interacted together to couple myogenesis and angiogenesis in vitro and in vivo during skeletal muscle regeneration. Kinetics of gene expression of ECs and MPCs sorted at different time points of regeneration identified three effectors secreted by both ECs and MPCs. Apelin, Oncostatin M, and Periostin were shown to control myogenesis/angiogenesis coupling in vitro and to be required for myogenesis and vessel formation during muscle regeneration in vivo. Furthermore, restorative macrophages, which have been previously shown to support myogenesis in vivo, were shown in a 3D triculture model to stimulate myogenesis/angiogenesis coupling, notably through Oncostatin M production. Our data demonstrate that restorative macrophages orchestrate muscle regeneration by controlling myogenesis/angiogenesis coupling. : In this study, Chazaud et al. demonstrate that endothelial cells (ECs) and myogenic progenitor cells (MPCs) interacted to couple myogenesis and angiogenesis during skeletal muscle regeneration. EC- and MPC-derived Apelin, Oncostatin M, and Periostin controlled myogenesis/angiogenesis coupling and were required for myogenesis and vessel formation. They show that, via the production of Oncostatin M, restorative macrophages promoted myogenesis/angiogenesis coupling. Keywords: muscle stem cells, myogenesis, angiogenesis, skeletal muscle regeneration, macrophage

AMPKα1-LDH pathway regulates muscle stem cell self-renewal by controlling metabolic homeostasis.

Control of stem cell fate to either enter terminal differentiation versus returning to quiescence (self-renewal) is crucial for tissue repair. Here, we showed that AMP-activated protein kinase (AMPK), the master metabolic regulator of the cell, controls muscle stem cell (MuSC) self-renewal. AMPKα1 MuSCs displayed a high self-renewal rate, which impairs muscle regeneration. AMPKα1 MuSCs showed a Warburg-like switch of their metabolism to higher glycolysis. We identified lactate dehydrogenase (LDH) as a new functional target of AMPKα1. LDH, which is a non-limiting enzyme of glycolysis in differentiated cells, was tightly regulated in stem cells. In functional experiments, LDH overexpression phenocopied AMPKα1 phenotype, that is shifted MuSC metabolism toward glycolysis triggering their return to quiescence, while inhibition of LDH activity rescued AMPKα1 MuSC self-renewal. Finally, providing specific nutrients (galactose/glucose) to MuSCs directly controlled their fate through the AMPKα1/LDH pathway, emphasizing the importance of metabolism in stem cell fate