Effects of fish oils on ex vivo B-cell responses of obese subjects upon BCR/TLR stimulation: a pilot study

The long-chain n-3 polyunsaturated fatty acids (LC-PUFAs) eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) in fish oil have immunomodulatory properties. B cells are a poorly studied target of EPA/DHA in humans. Therefore, in this pilot study, we tested how n-3 LC-PUFAs influence B-cell responses of obese humans. Obese men and women were assigned to consume four 1-g capsules per day of olive oil (OO, n=12), fish oil (FO, n=12) concentrate or high-DHA-FO concentrate (n=10) for 12 weeks in a parallel design. Relative to baseline, FO (n=9) lowered the percentage of circulating memory and plasma B cells, whereas the other supplements had no effect. There were no postintervention differences between the three supplements. Next, ex vivo B-cell cytokines were assayed after stimulation of Toll-like receptors (TLRs) and/or the B-cell receptor (BCR) to determine if the effects of n-3 LC-PUFAs were pathway-dependent. B-cell IL-10 and TNFα secretion was respectively increased with high DHA-FO (n=10), relative to baseline, with respective TLR9 and TLR9 + BCR stimulation. OO (n=12) and FO (n=12) had no influence on B-cell cytokines compared to baseline, and there were no differences in postintervention cytokine levels between treatment groups. Finally, ex vivo antibody levels were assayed with FO (n=7) after TLR9 + BCR stimulation. Compared to baseline, FO lowered IgM but not IgG levels accompanied by select modifications to the plasma lipidome. Altogether, the results suggest that n-3 LC-PUFAs could modulate B-cell activity in humans, which will require further testing in a larger cohort

Reduced CD27-IgD- B cells in blood and raised CD27-IgD- B cells in gut-associated lymphoid tissue in inflammatory bowel disease.

The intestinal mucosa in inflammatory bowel disease (IBD) contains increased frequencies of lymphocytes and a disproportionate increase in plasma cells secreting immunoglobulin (Ig)G relative to other isotypes compared to healthy controls. Despite consistent evidence of B lineage cells in the mucosa in IBD, little is known of B cell recruitment to the gut in IBD. Here we analyzed B cells in blood of patients with Crohn's disease (CD) and ulcerative colitis (UC) with a range of disease activities. We analyzed the frequencies of known B cell subsets in blood and observed a consistent reduction in the proportion of CD27−IgD− B cells expressing all Ig isotypes in the blood in IBD (independent of severity of disease and treatment) compared to healthy controls. Successful treatment of patients with biologic therapies did not change the profile of B cell subsets in blood. By mass cytometry we demonstrated that CD27−IgD− B cells were proportionately enriched in the gut-associated lymphoid tissue (GALT) in IBD. Since production of TNFα is a feature of IBD relevant to therapies, we sought to determine whether B cells in GALT or the CD27−IgD− subset in particular could contribute to pathology by secretion of TNFα or IL-10. We found that donor matched GALT and blood B cells are capable of producing TNFα as well as IL-10, but we saw no evidence that CD27−IgD− B cells from blood expressed more TNFα compared to other subsets. The reduced proportion of CD27−IgD− B cells in blood and the increased proportion in the gut implies that CD27−IgD− B cells are recruited from the blood to the gut in IBD. CD27−IgD− B cells have been implicated in immune responses to intestinal bacteria and recruitment to GALT, and may contribute to the intestinal inflammatory milieu in IBD

Human marginal zone B cell development from early T2 progenitors.

B cells emerge from the bone marrow as transitional (TS) B cells that differentiate through T1, T2, and T3 stages to become naive B cells. We have identified a bifurcation of human B cell maturation from the T1 stage forming IgMhi and IgMlo developmental trajectories. IgMhi T2 cells have higher expression of α4β7 integrin and lower expression of IL-4 receptor (IL4R) compared with the IgMlo branch and are selectively recruited into gut-associated lymphoid tissue. IgMhi T2 cells also share transcriptomic features with marginal zone B cells (MZBs). Lineage progression from T1 cells to MZBs via an IgMhi trajectory is identified by pseudotime analysis of scRNA-sequencing data. Reduced frequency of IgMhi gut-homing T2 cells is observed in severe SLE and is associated with reduction of MZBs and their putative IgMhi precursors. The collapse of the gut-associated MZB maturational axis in severe SLE affirms its existence in health

Resolvin E1 Derived from Eicosapentaenoic Acid Prevents Hyperinsulinemia and Hyperglycemia in a Host Genetic Manner

The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology Eicosapentaenoic acid (EPA) has garnered attention after the success of the REDUCE-IT trial, which contradicted previous conclusions on EPA for cardiovascular disease risk. Here we first investigated EPA\u27s preventative role on hyperglycemia and hyperinsulinemia. EPA ethyl esters prevented obesity-induced glucose intolerance, hyperinsulinemia, and hyperglycemia in C57BL/6J mice. Supporting NHANES analyses showed that fasting glucose levels of obese adults were inversely related to EPA intake. We next investigated how EPA improved murine hyperinsulinemia and hyperglycemia. EPA overturned the obesity-driven decrement in the concentration of 18-hydroxyeicosapentaenoic acid (18-HEPE) in white adipose tissue and liver. Treatment of obese inbred mice with RvE1, the downstream immunoresolvant metabolite of 18-HEPE, but not 18-HEPE itself, reversed hyperinsulinemia and hyperglycemia through the G-protein coupled receptor ERV1/ChemR23. To translate the findings, we determined if the effects of RvE1 were dependent on host genetics. RvE1\u27s effects on hyperinsulinemia and hyperglycemia were divergent in diversity outbred mice that model human genetic variation. Secondary SNP analyses further confirmed extensive genetic variation in human RvE1/EPA-metabolizing genes. Collectively, the data suggest EPA prevents hyperinsulinemia and hyperglycemia, in part, through RvE1\u27s activation of ERV1/ChemR23 in a host genetic manner. The studies underscore the need for personalized administration of RvE1 based on genetic/metabolic enzyme profiles

Intestinal epithelial cells in immune response inducting during cryptosporidium parvum infection : roles of antimicrobial peptides and miroRNAs

Le projet de ma thèse a consisté à étudier chez les nouveau-nés la réponse des cellules épithéliales intestinales (IEC) en microARN (miR) et en peptides antimicrobiens (PAM) dans le contexte de l’infection par Cryptosporidium parvum. Ce protozoaire monoxène se développe uniquement dans les IEC et affecte plus particulièrement les nouveau-nés et les individus immunodéprimés. Nous avons étudié la réponse en miR dans les IEC après infection par C. parvum. La comparaison des réponses obtenues dans les IEC in vitro et in vivo nous a permis de montrer que l’expression du miR-181d-5p est diminuée durant l’infection et que cette diminution d’expression lèverait l’inhibition de l’expression des facteurs anti-apoptotiques OPG et BCL2, favorisant la survie du parasite dans les IEC. Nous avons également caractérisé l’impact de C. parvum sur l’expression des PAM chez le nouveau-né et leur rôle durant l’infection. Nous avons mis en évidence que l’infection entraine une forte modification de l’expression des PAM. Notre attention a été retenue par la diminution, surprenante, de l’expression de la chimiokine antimicrobienne CCL20 et de la cathélicidine CRAMP au cours de l’infection. Pour ces deux peptides, nous avons montré qu’une administration aux souriceaux réduisait significativement la charge parasitaire. Nous avons pu montrer que la protection induite par ces deux molécules antimicrobiennes résultait de leur activité parasiticide sur C. parvum. Ainsi, leur diminution d’expression semble être favorable au développement du parasite et nous avons suggéré qu’elle puisse être induite par le parasite pour échapper à cette activité parasiticide avec notamment la modulation de certains miR.The aim of my thesis was to study in the mouse model, the intestinal epithelial cell (IEC) response during neonatal Cryptosporidium parvum infection with a focus on microRNAs (miR) and antimicrobial peptides (AMP) response. C. parvum is a protozoan parasite that affects preferentially newborn, young or immunocompromised adult and completes its life cycle only in IECs. In a first part, we studied the expression of miRs in IEC during C. parvum infection. We compared the responses between in vitro infected IEC and IECs purified from infected neonatal mice and observed a decrease of miR-181d-5p expression. This reduced expression of miR-181d-5p was associated with an upregulation of the mRNA coding for two putative targets OPG and BCL2 which are anti-apoptotic agents that may favor parasite survival in IEC. This functional relation between miR-181d-5p and OPG was next demonstrated by using reporter dual-luciferase assay. In a second part of my thesis, we characterized the AMP expression profile and studied their role during C. parvum infection in neonates. We showed that infection up-regulates a broad expression of AMP except for CCL20 and CRAMP cathelicidin for which mRNA expression was decreased. We next choose to focus our work on these two molecules and reported that administration of CCL20 and CRAMP to infected neonatal mice significantly reduced the number of parasites in the intestine through a direct killing activity on free stages of the parasite. As the decreased expression of these two AMPs during infection seems to favor the development of the parasite, this could be an escape mechanism developed by C. parvum that may occur through the modulation of miR

La cellule épithéliale intestinale dans l'induction des réponses immunitaires au cours de l'infection par <em>Cryptosporidium parvum</em> : rôles des peptides antimicrobiens et des microARN

After birth, the gut is exposed to many environmental changes, like colonization by microbiota and first contacts with food antigens and pathogens. This requires a fine tuning of the immune response in which microRNAs (miR) play an important role. In this neonatal period, innate immune responses are essential to control infections and antimicrobial peptides (AMP) are major components of this response. The aim of my thesis was to study in the mouse model, the intestinal epithelial cell (IEC) response during neonatal Cryptosporidium parvum infection with a focus on miR and AMP response. C. parvum is a protozoan parasite that affects preferentially newborn, young or immunocompromised adult and completes its life cycle only in IECs. Therefore, C. parvum infection is an excellent model for studying the role of IEC in triggering the intestinal immune response in neonates. In a first part, we studied the expression of known inflammation-regulatory miRs in IEC during C. parvum infection. We compared the responses between in vitro infected IEC and IECs purified from infected neonatal mice and observed a decrease of miR-181d-5p expression. This reduced expression of miR-181d-5p was associated with an upregulation of the mRNA coding for two putative targets OPG and BCL2 which are anti-apoptotic agents that may favor parasite survival in IEC. This functional relation between miR-181d-5p and OPG was next clearly demonstrated by using reporter dual-luciferase assay. In a second part of my thesis, we characterized the AMP expression profile and studied their role during C. parvum infection in neonates. We showed that infection up-regulates a broad expression of AMP from different families except for CCL20 and CRAMP cathelicidin for which mRNA expression was decreased. We next choose to focus our work on these two molecules and reported that exogenous administration of CCL20 and CRAMP to infected neonatal mice significantly reduced the number of parasites in the intestine through a direct killing activity on free stages of the parasite. As the decreased expression of these two AMPs during infection seems to favor the development of the parasite, we propose that this could be an escape mechanism developed by C. parvum that may occur through the modulation of miR expression.Pendant la période post-natale, l’intestin est exposé à de nombreux changements environnementaux dont la colonisation par la flore, les antigènes alimentaires et le contact avec les premiers pathogènes. Dans ce contexte, le nouveau-né doit à la fois se défendre au mieux des infections, notamment grâce aux peptides antimicrobiens (PAM) et doit également éviter une inflammation excessive en mettant en place des mécanismes de régulation telle que la production de microARN (miR). Le projet de ma thèse a consisté à étudier chez les nouveau-nés la réponse des cellules épithéliales intestinales (IEC) en miR et en PAM dans le contexte de l’infection par Cryptosporidium parvum. Ce protozoaire monoxène se développe uniquement dans les IEC et affecte plus particulièrement les jeunes ou nouveau-nés et les individus immunodéprimés, ce qui en fait un excellent modèle d’étude du rôle des IEC dans l’induction des réponses immunitaires intestinales et notamment chez les nouveau-nés. Dans une première partie, nous avons étudié la réponse d’un large panel de miR connus pour être impliqués dans la régulation des réponses inflammatoires, dans les IEC après infection par C. parvum. La comparaison des réponses obtenus dans les IEC après infection in vitro et après purification à partir de souriceaux infectés nous a permis de montrer que l’expression du miR-181d-5p est diminuée durant l’infection et que cette diminution d’expression lèverait l’inhibition de l’expression des facteurs anti-apoptotiques OPG et BCL2, favorisant la survie du parasite dans les IEC. Une seconde partie de mon travail a consisté à caractériser l’impact de C. parvum sur l’expression des PAM appartenant aux différentes familles chez le nouveau et leur rôle durant l’infection. Nous avons mis en évidence que l’infection entraine une forte modification de l’expression des PAM des différentes familles. Notre attention a été retenue par la diminution, surprenante, de l’expression de la chimiokine CCL20, aux propriétés antimicrobiennes connues sur des bactéries et de la cathélicidine CRAMP au cours de l’infection. Pour ces deux molécules à activité antimicrobienne, nous avons mis en évidence qu’une administration exogène aux souriceaux réduisait significativement le nombre de parasite dans l’intestin. Malgré des propriétés immunomodulatrices décrites dans d’autres modèles, nous avons pu montrer que la protection induite par ces deux molécules à activité antimicrobienne résultait de leur activité parasiticide sur C. parvum. Ainsi, leur diminution d’expression in vivo semble être favorable au développement du parasite et nous avons suggéré qu’elle puisse être induite par le parasite pour échapper à cette activité parasiticide avec notamment la modulation de certains miRs

miRNAs during <em>Cryptosporidium parvum</em> infection ?

National audienc

Role of Paneth cells during cryptosporidiosis : first results in a mouse model of neonatal cryptosporidiosis

National audienc

Role of Paneth cells during infection of neonatal mice by Cryptosporidium parvum

Cryptosporidium parvum is a zoonotic apicomplexan parasite responsible for a diarrheal disease named cryptosporidiosis. This protozoan parasite is found worldwide and is transmitted by contaminated water. The immature intestinal immune system in very young animals and children under 5 places them at high risk of developing severe cryptosporidiosis. Paneth cells (PC) are specialized intestinal epithelial cells located at the base of intestinal crypts producing antimicrobial peptides (AMPs) that develop and mature after birth. We and others have already described in vitro that antimicrobial peptides such as CRAMP and CCL20 can alter the viability of sporozoites of C. parvum (1). We therefore wondered whether PCs and the AMPs that they produce can participate in the protective innate immune response against the parasite. By using a mouse model of neonatal cryptosporidiosis, we investigated the role of Paneth cells in the innate immune response against C. parvum. We first compared the susceptibility to C. parvum of mice genetically modified to be depleted of PCs (Sox9flox/flox-vil-Cre mice) and observed an increased level of infection when PCs are absent, associated with a reduced expression of AMPs. We also determined the effect of Cryptosporidium parvum infection on PC development and activity. By immunofluorescence, we observed on intestinal sections that C. parvum infection decreases the number of granule-positive-PCs and lysozymepositive- PCs in neonatal mice. Altogether, these first results clearly demonstrate that PCs are important contributors of the innate protective immune response in mice and that lyzozyme, already described to be efficient in vitro on C. parvum sporozoite viability, may be involved in this effect