Dual molecule targeting HDAC6 leads to intratumoral CD4+ cytotoxic lymphocytes recruitment through MHC-II upregulation on lung cancer cells.

BACKGROUND: Despite the current therapeutic treatments including surgery, chemotherapy, radiotherapy and more recently immunotherapy, the mortality rate of lung cancer stays high. Regarding lung cancer, epigenetic modifications altering cell cycle, angiogenesis and programmed cancer cell death are therapeutic targets to combine with immunotherapy to improve treatment success. In a recent study, we uncovered that a molecule called QAPHA ((E)-3-(5-((2-cyanoquinolin-4-yl)(methyl)amino)-2-methoxyphenyl)-N-hydroxyacrylamide) has a dual function as both a tubulin polymerization and HDAC inhibitors. Here, we investigate the impact of this novel dual inhibitor on the immune response to lung cancer. METHODS: To elucidate the mechanism of action of QAPHA, we conducted a chemical proteomics analysis. Using an in vivo mouse model of lung cancer (TC-1 tumor cells), we assessed the effects of QAPHA on tumor regression. Tumor infiltrating immune cells were characterized by flow cytometry. RESULTS: In this study, we first showed that QAPHA effectively inhibited histone deacetylase 6, leading to upregulation of HSP90, cytochrome C and caspases, as revealed by proteomic analysis. We confirmed that QAPHA induces immunogenic cell death (ICD) by expressing calreticulin at cell surface in vitro and demonstrated its efficacy as a vaccine in vivo. Remarkably, even at a low concentration (0.5 mg/kg), QAPHA achieved complete tumor regression in approximately 60% of mice treated intratumorally, establishing a long-lasting anticancer immune response. Additionally, QAPHA treatment promoted the infiltration of M1-polarized macrophages in treated mice, indicating the induction of a pro-inflammatory environment within the tumor. Very interestingly, our findings also revealed that QAPHA upregulated major histocompatibility complex class II (MHC-II) expression on TC-1 tumor cells both in vitro and in vivo, facilitating the recruitment of cytotoxic CD4+T cells (CD4+CTL) expressing CD4+, NKG2D+, CRTAM+, and Perforin+. Finally, we showed that tumor regression strongly correlates to MHC-II expression level on tumor cell and CD4+ CTL infiltrate. CONCLUSION: Collectively, our findings shed light on the discovery of a new multitarget inhibitor able to induce ICD and MHC-II upregulation in TC-1 tumor cell. These two processes participate in enhancing a specific CD4+ cytotoxic T cell-mediated antitumor response in vivo in our model of lung cancer. This breakthrough suggests the potential of QAPHA as a promising agent for cancer treatment.

Faecalibacterium duncaniae as a novel next generation probiotic against influenza.

The gut-lung axis is critical during viral respiratory infections such as influenza. Gut dysbiosis during infection translates into a massive drop of microbially produced short-chain fatty acids (SCFAs). Among them, butyrate is important during influenza suggesting that microbiome-based therapeutics targeting butyrate might hold promises. The butyrate-producing bacterium Faecalibacterium duncaniae (formerly referred to as F. prausnitzii) is an emerging probiotic with several health-promoting characteristics. To investigate the potential effects of F. duncaniae on influenza outcomes, mice were gavaged with live F. duncaniae (A2-165 or I-4574 strains) five days before infection. Supplementation of F. duncaniae was associated with less severe disease, a lower pulmonary viral load, and lower levels of lung inflammation. F. duncaniae supplementation impacted on gut dysbiosis induced by infection, as assessed by 16S rRNA sequencing. Interestingly, F. duncaniae administration was associated with a recovery in levels of SCFAs (including butyrate) in infected animals. The live form of F. duncaniae was more potent that the pasteurized form in improving influenza outcomes. Lastly, F. duncaniae partially protected against secondary (systemic) bacterial infection. We conclude that F. duncaniae might serve as a novel next generation probiotic against acute viral respiratory diseases.

Oral tryptophan activates duodenal aryl hydrocarbon receptor in healthy subjects: a crossover randomized controlled trial.

Background and Aims: Tryptophan is an essential amino acid transformed by host and gut microbial enzymes into metabolites that regulate mucosal homeostasis through Aryl hydrocarbon receptor (AhR) activation. Alteration of tryptophan metabolism has been associated with chronic inflammation, however whether tryptophan supplementation affects the metabolite repertoire and AhR activation under physiologic conditions in humans, is unknown. Methods: We performed a randomized, double blind, placebo-controlled, crossover study in 20 healthy volunteers. Subjects on a low tryptophan background diet were randomly assigned to a 3-week L-tryptophan supplementation (3 g/day) or placebo, and after a 2-week washout switched to opposite interventions. We assessed gastrointestinal and psychological symptoms by validated questionnaires, AhR activation by cell reporter assay, tryptophan metabolites by liquid chromatography and high-resolution mass spectrometry, cytokine production in isolated monocytes by ELISA and microbiota profile by 16S rRNA Illumina technique. Results: Oral tryptophan supplementation was well tolerated, with no changes in gastrointestinal or psychological scores. Compared with placebo, tryptophan increased AhR activation capacity by duodenal contents, but not by feces. This was paralleled by higher urinary and plasma kynurenine metabolites and indoles. Tryptophan had a modest impact on fecal microbiome profiles, and no significant effect on cytokine production. Conclusions: At the doses used in this study, oral tryptophan supplementation in humans induces microbial indole and host kynurenine metabolic pathways in the small intestine, known to be immunomodulatory. The results should prompt tryptophan intervention strategies in inflammatory conditions of the small intestine where the AhR pathway is impaired.

From animal models to gut-on-chip: the challenging journey to capture inter-individual variability in chronic digestive disorders.

Chronic digestive disorders are of increasing incidence worldwide with expensive treatments and no available cure. Available therapeutic schemes mainly rely on symptom relief, with large degrees of variability in patients' response to such treatments, underlining the need for new therapeutic strategies. There are strong indications that the gut microbiota's contribution seems to be a key modulator of disease activity and patients' treatment responses. Hence, efforts have been devoted to understanding host-microbe interactions and the mechanisms underpinning such variability. Animal models, being the gold standard, provide valuable mechanistic insights into host-microbe interactions. However, they are not exempt from limitations prompting the development of alternative methods. Emerging microfluidic technologies and gut-on-chip models were shown to mirror the main features of gut physiology and disease state, reflect microbiota modification, and include functional readouts for studying host responses. In this commentary, we discuss the relevance of animal models in understanding host-microbe interactions and how gut-on-chip technology holds promises for addressing patient variability in responses to chronic digestive disease treatment.

The gut microbiota posttranslationally modifies IgA1 in autoimmune glomerulonephritis.

Mechanisms underlying the disruption of self-tolerance in acquired autoimmunity remain unclear. Immunoglobulin A (IgA) nephropathy is an acquired autoimmune disease where deglycosylated IgA1 (IgA subclass 1) auto-antigens are recognized by IgG auto-antibodies, forming immune complexes that are deposited in the kidneys, leading to glomerulonephritis. In the intestinal microbiota of patients with IgA nephropathy, there was increased relative abundance of mucin-degrading bacteria, including Akkermansia muciniphila. IgA1 was deglycosylated by A. muciniphila both in vitro and in the intestinal lumen of mice. This generated neo-epitopes that were recognized by autoreactive IgG from the sera of patients with IgA nephropathy. Mice expressing human IgA1 and the human Fc α receptor I (α1KI-CD89tg) that underwent intestinal colonization by A. muciniphila developed an aggravated IgA nephropathy phenotype. After deglycosylation of IgA1 by A. muciniphila in the mouse gut lumen, IgA1 crossed the intestinal epithelium into the circulation by retrotranscytosis and became deposited in the glomeruli of mouse kidneys. Human α-defensins-a risk locus for IgA nephropathy-inhibited growth of A. muciniphila in vitro. A negative correlation observed between stool concentration of α-defensin 6 and quantity of A. muciniphila in the guts of control participants was lost in patients with IgA nephropathy. This study demonstrates that gut microbiota dysbiosis contributes to generation of auto-antigens in patients with IgA nephropathy and in a mouse model of this disease.

Standards for fecal microbiota transplant: Tools and therapeutic advances.

Fecal microbiota transplantation (FMT) has been demonstrated to be efficacious in preventing recurrent Clostridioides difficile (C. difficile) infections, and is being investigated for treatment of several other diseases including inflammatory bowel disease, cancer, obesity, liver disease, and diabetes. To speed up the translation of FMT into clinical practice as a safe and standardized therapeutic intervention, additional evidence-based technical and regulatory guidance is needed. To this end in May of 2022, the International Alliance for Biological Standardization (IABS) and the BIOASTER Microbiology Technology Institute hosted a second webinar to discuss key issues still impeding the advancement and standardization of FMT. The goal of this two-day webinar was to provide a forum for scientific experts to share and discuss data and key challenges with one another. Discussion included a focus on the evaluation of safety, efficacy, clinical trial design, reproducibility and accuracy in obtained microbiome measurements and data reporting, and the potential for standardization across these areas. It also focused on increasing the application potential and visibility of FMT beyond treating C. difficile infections.

Can the Evidence-Based Use of Probiotics (Notably Saccharomyces boulardii CNCM I-745 and Lactobacillus rhamnosus GG) Mitigate the Clinical Effects of Antibiotic-Associated Dysbiosis?

Dysbiosis corresponds to the disruption of a formerly stable, functionally complete microbiota. In the gut, this imbalance can lead to adverse health outcomes in both the short and long terms, with a potential increase in the lifetime risks of various noncommunicable diseases and disorders such as atopy (like asthma), inflammatory bowel disease, neurological disorders, and even behavioural and psychological disorders. Although antibiotics are highly effective in reducing morbidity and mortality in infectious diseases, antibiotic-associated diarrhoea is a common, non-negligible clinical sign of gut dysbiosis (and the only visible one). Re-establishment of a normal (functional) gut microbiota is promoted by completion of the clinically indicated course of antibiotics, the removal of any other perturbing external factors, the passage of time (i.e. recovery through the microbiota's natural resilience), appropriate nutritional support, and-in selected cases-the addition of probiotics. Systematic reviews and meta-analyses of clinical trials have confirmed the strain-specific efficacy of some probiotics (notably the yeast Saccharomyces boulardii CNCM I-745 and the bacterium Lactobacillus rhamnosus GG) in the treatment and/or prevention of antibiotic-associated diarrhoea in children and in adults. Unusually for a probiotic, S. boulardii is a eukaryote and is not therefore directly affected by antibiotics-making it suitable for administration in cases of antibiotic-associated diarrhoea. A robust body of evidence from clinical trials and meta-analyses shows that the timely administration of an adequately dosed probiotic (upon initiation of antibiotic treatment or within 48 h) can help to prevent or resolve the consequences of antibiotic-associated dysbiosis (such as diarrhoea) and promote the resilience of the gut microbiota and a return to the pre-antibiotic state. A focus on the prescription of evidence-based, adequately dosed probiotics should help to limit unjustified and potentially ineffective self-medication.

Faecalibacterium duncaniae A2-165 regulates the expression of butyrate synthesis, ferrous iron uptake, and stress-response genes based on acetate consumption.

The promising next-generation probiotic Faecalibacterium prausnitzii is one of the most abundant acetate-consuming, butyrate-producing bacteria in the healthy human gut. Yet, little is known about how acetate availability affects this bacterium's gene expression strategies. Here, we investigated the effect of acetate on temporal changes in the transcriptome of F. duncaniae A2-165 cultures using RNA sequencing. We compared gene expression patterns between two growth phases (early stationary vs. late exponential) and two acetate levels (low: 3 mM vs. high: 23 mM). Only in low-acetate conditions, a general stress response was activated. In high-acetate conditions, there was greater expression of genes related to butyrate synthesis and to the importation of B vitamins and iron. Specifically, expression was strongly activated in the case of the feoAABC operon, which encodes a FeoB ferrous iron transporter, but not in the case of the feoAB gene, which encodes a second putative FeoAB transporter. Moreover, excess ferrous iron repressed feoB expression but not feoAB. Lastly, FeoB but not FeoAB peptides from strain A2-165 were found in abundance in a healthy human fecal metaproteome. In conclusion, we characterized two early-stationary transcriptomes based on acetate consumption and this work highlights the regulation of feoB expression in F. duncaniae A2-165.

Gut microbiota alterations are associated with phenotype and genotype in familial Mediterranean fever.

OBJECTIVE: FMF is the most common monogenic autoinflammatory disease associated with MEFV mutations. Disease phenotype and response to treatment vary from one patient to another, despite similar genotype, suggesting the role of environmental factors. The objective of this study was to analyse the gut microbiota of a large cohort of FMF patients in relation to disease characteristics. METHODS: The gut microbiotas of 119 FMF patients and 61 healthy controls were analysed using 16 s rRNA gene sequencing. Associations between bacterial taxa, clinical characteristics, and genotypes were evaluated using multivariable association with linear models (MaAslin2), adjusting on age, sex, genotype, presence of AA amyloidosis (n = 17), hepatopathy (n = 5), colchicine intake, colchicine resistance (n = 27), use of biotherapy (n = 10), CRP levels, and number of daily faeces. Bacterial network structures were also analysed. RESULTS: The gut microbiotas of FMF patients differ from those of controls in having increased pro-inflammatory bacteria, such as the Enterobacter, Klebsiella and Ruminococcus gnavus group. Disease characteristics and resistance to colchicine correlated with homozygous mutations and were associated with specific microbiota alteration. Colchicine treatment was associated with the expansion of anti-inflammatory taxa such as Faecalibacterium and Roseburia, while FMF severity was associated with expansion of the Ruminococcus gnavus group and Paracoccus. Colchicine-resistant patients exhibited an alteration of the bacterial network structure, with decreased intertaxa connectivity. CONCLUSION: The gut microbiota of FMF patients correlates with disease characteristics and severity, with an increase in pro-inflammatory taxa in the most severe patients. This suggests a specific role for the gut microbiota in shaping FMF outcomes and response to treatment.

Counteracting tryptophan metabolism alterations as a new therapeutic strategy for rheumatoid arthritis.

OBJECTIVES: Alterations in tryptophan (Trp) metabolism have been reported in inflammatory diseases, including rheumatoid arthritis (RA). However, understanding whether these alterations participate in RA development and can be considered putative therapeutic targets remains undetermined.In this study, we combined quantitative Trp metabolomics in the serum from patients with RA and corrective administration of a recombinant enzyme in experimental arthritis to address this question. METHODS: Targeted quantitative Trp metabolomics was performed on the serum from 574 previously untreated patients with RA from the ESPOIR (Etude et Suivi des POlyarthrites Indifférenciées Récentes) cohort and 98 healthy subjects. A validation cohort involved 69 established patients with RA. Dosages were also done on the serum of collagen-induced arthritis (CIA) and collagen antibody-induced arthritis (CAIA) mice and controls. A proof-of-concept study evaluating the therapeutic potency of targeting the kynurenine pathway was performed in the CAIA model. RESULTS: Differential analysis revealed dramatic changes in Trp metabolite levels in patients with RA compared with healthy controls. Decreased levels of kynurenic (KYNA) and xanthurenic (XANA) acids and indole derivatives, as well as an increased level of quinolinic acid (QUIN), were found in the serum of patients with RA. They correlated positively with disease severity (assessed by both circulating biomarkers and disease activity scores) and negatively with quality-of-life scores. Similar profiles of kynurenine pathway metabolites were observed in the CAIA and CIA models. From a mechanistic perspective, we demonstrated that QUIN favours human fibroblast-like synoviocyte proliferation and affected their cellular metabolism, through inducing both mitochondrial respiration and glycolysis. Finally, systemic administration of the recombinant enzyme aminoadipate aminotransferase, responsible for the generation of XANA and KYNA, was protective in the CAIA model. CONCLUSIONS: Altogether, our preclinical and clinical data indicate that alterations in the Trp metabolism play an active role in the pathogenesis of RA and could be considered as a new therapeutic avenue.

Neutrophils: from IBD to the gut microbiota.

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract that results from dysfunction in innate and/or adaptive immune responses. Impaired innate immunity, which leads to lack of control of an altered intestinal microbiota and to activation of the adaptive immune system, promotes a secondary inflammatory response that is responsible for tissue damage. Neutrophils are key players in innate immunity in IBD, but their roles have been neglected compared with those of other immune cells. The latest studies on neutrophils in IBD have revealed unexpected complexities, with heterogeneous populations and dual functions, both deleterious and protective, for the host. In parallel, interconnections between disease development, intestinal microbiota and neutrophils have been highlighted. Numerous IBD susceptibility genes (such as NOD2, NCF4, LRRK2, CARD9) are involved in neutrophil functions related to defence against microorganisms. Moreover, severe monogenic diseases involving dysfunctional neutrophils, including chronic granulomatous disease, are characterized by intestinal inflammation that mimics IBD and by alterations in the intestinal microbiota. This observation demonstrates the dialogue between neutrophils, gut inflammation and the microbiota. Neutrophils affect microbiota composition and function in several ways. In return, microbial factors, including metabolites, regulate neutrophil production and function directly and indirectly. It is crucial to further investigate the diverse roles played by neutrophils in host-microbiota interactions, both at steady state and in inflammatory conditions, to develop new IBD therapies. In this Review, we discuss the roles of neutrophils in IBD, in light of emerging evidence proving strong interconnections between neutrophils and the gut microbiota, especially in an inflammatory context.

Gut dysbiosis in Crohn's disease: Never so close to solving the chicken-and-egg enigma: Commentary to "Gut microbiome composition is associated with future onset of Crohn's disease in healthy first-degree relatives, by Raygoza Garay JA et al., Gastroenterology 2023".

Crohn's disease (CD) is a chronic disease of the digestive tract whose pathogenesis remains not fully understood. Several studies have implicated the gut microbiota as a key player in the onset of gut inflammation. However, most of the data is based on case-control studies comparing patients with established disease with controls, usually healthy individuals. The study by Raygoza Garay and colleagues shows for the first time that changes in the composition of the gut microbiota precede CD onset by up to five years. The authors developed a microbiome risk score using a machine-learning model that included bacterial composition and clinical variables from a large cohort of healthy first-degree relatives of patients with CD. This study provides strong evidence that the alterations of the gut microbiota is causal in CD pathogenesis and suggest that early intervention targeting it may be an appropriate preventive strategy.

Recommendations to Improve Quality of Probiotic Systematic Reviews With Meta-Analyses.

Importance: Systematic reviews and meta-analyses often report conflicting results when assessing evidence for probiotic efficacy, partially because of the lack of understanding of the unique features of probiotic trials. As a consequence, clinical decisions on the use of probiotics have been confusing. Objective: To provide recommendations to improve the quality and consistency of systematic reviews with meta-analyses on probiotics, so evidence-based clinical decisions can be made with more clarity. Evidence Review: For this consensus statement, an updated literature review was conducted (January 1, 2020, to June 30, 2022) to supplement a previously published 2018 literature search to identify areas where probiotic systematic reviews with meta-analyses might be improved. An expert panel of 21 scientists and physicians with experience on writing and reviewing probiotic reviews and meta-analyses was convened and used a modified Delphi method to develop recommendations for future probiotic reviews. Findings: A total of 206 systematic reviews with meta-analysis components on probiotics were screened and representative examples discussed to determine areas for improvement. The expert panel initially identified 36 items that were inconsistently reported or were considered important to consider in probiotic meta-analyses. Of these, a consensus was reached for 9 recommendations to improve the quality of future probiotic meta-analyses. Conclusions and Relevance: In this study, the expert panel reached a consensus on 9 recommendations that should promote improved reporting of probiotic systematic reviews with meta-analyses and, thereby, assist in clinical decisions regarding the use of probiotics.

NLRP6 controls pulmonary inflammation from cigarette smoke in a gut microbiota-dependent manner.

Chronic obstructive pulmonary disease (COPD) is a major health issue primarily caused by cigarette smoke (CS) and characterized by breathlessness and repeated airway inflammation. NLRP6 is a cytosolic innate receptor controlling intestinal inflammation and orchestrating the colonic host-microbial interface. However, its roles in the lungs remain largely unexplored. Using CS exposure models, our data show that airway inflammation is strongly impaired in Nlrp6-deficient mice with drastically fewer recruited neutrophils, a key cell subset in inflammation and COPD. We found that NLRP6 expression in lung epithelial cells is important to control airway and lung tissue inflammation in an inflammasome-dependent manner. Since gut-derived metabolites regulate NLRP6 inflammasome activation in intestinal epithelial cells, we investigated the link between NLRP6, CS-driven lung inflammation, and gut microbiota composition. We report that acute CS exposure alters gut microbiota in both wild-type (WT) and Nlrp6-deficient mice and that antibiotic treatment decreases CS-induced lung inflammation. In addition, gut microbiota transfer from dysbiotic Nlrp6-deficient mice to WT mice decreased airway lung inflammation in WT mice, highlighting an NLRP6-dependent gut-to-lung axis controlling pulmonary inflammation.

An obesogenic diet increases atherosclerosis through promoting microbiota dysbiosis-induced gut lymphocyte trafficking into the periphery.

Although high-fat diet (HFD)-induced gut microbiota dysbiosis is known to affect atherosclerosis, the underlying mechanisms remain to be fully explored. Here, we show that the progression of atherosclerosis depends on a gut microbiota shaped by an HFD but not a high-cholesterol (HC) diet and, more particularly, on low fiber (LF) intake. Mechanistically, gut lymphoid cells impacted by HFD- or LF-induced microbiota dysbiosis highly proliferate in mesenteric lymph nodes (MLNs) and migrate from MLNs to the periphery, which fuels T cell accumulation within atherosclerotic plaques. This is associated with the induction of mucosal addressin cell adhesion molecule 1 (MAdCAM-1) within plaques and the presence of enterotropic lymphocytes expressing ß7 integrin. MLN resection or lymphocyte deficiency abrogates the pro-atherogenic effects of a microbiota shaped by LF. Our study shows a pathological link between a diet-shaped microbiota, gut immune cells, and atherosclerosis, suggesting that a diet-modulated microbiome might be a suitable therapeutic target to prevent atherosclerosis.

Cyberlindnera jadinii and Kluyveromyces lactis, two fungi used in food processes, have potential probiotic effects on gut inflammation.

IMPORTANCE: The food industry has always used many strains of microorganisms including fungi in their production processes. These strains have been widely characterized for their biotechnological value, but we still know very little about their interaction capacities with the host at a time when the intestinal microbiota is at the center of many pathologies. In this study, we characterized five yeast strains from food production which allowed us to identify two new strains with high probiotic potential and beneficial effects in a model of intestinal inflammation.

Regulation of Lung Immune Tone by the Gut-Lung Axis via Dietary Fiber, Gut Microbiota, and Short-Chain Fatty Acids.

Lung immune tone, i.e. the immune state of the lung, can vary between individuals and over a single individual's lifetime, and its basis and regulation in the context of inflammatory responses to injury is poorly understood. The gut microbiome, through the gut-lung axis, can influence lung injury outcomes but how the diet and microbiota affect lung immune tone is also unclear. We hypothesized that lung immune tone would be influenced by the presence of fiber-fermenting short-chain fatty acid (SCFA)-producing gut bacteria. To test this hypothesis, we conducted a fiber diet intervention study followed by lung injury in mice and profiled gut microbiota using 16S sequencing, metabolomics, and lung immune tone. We also studied germ-free mice to evaluate lung immune tone in the absence of microbiota and performed in vitro mechanistic studies on immune tone and metabolic programming of alveolar macrophages exposed to the SCFA propionate (C3). Mice on high-fiber diet were protected from sterile lung injury compared to mice on a fiber-free diet. This protection strongly correlated with lower lung immune tone, elevated propionate levels and enrichment of specific fecal microbiota taxa; conversely, lower levels of SCFAs and an increase in other fatty acid metabolites and bacterial taxa correlated with increased lung immune tone and increased lung injury in the fiber-free group. In vitro , C3 reduced lung alveolar macrophage immune tone (through suppression of IL-1ß and IL-18) and metabolically reprogrammed them (switching from glycolysis to oxidative phosphorylation after LPS challenge). Overall, our findings reveal that the gut-lung axis, through dietary fiber intake and enrichment of SCFA-producing gut bacteria, can regulate innate lung immune tone via IL-1ß and IL-18 pathways. These results provide a rationale for the therapeutic development of dietary interventions to preserve or enhance specific aspects of host lung immunity.

Genetic inhibition of CARD9 accelerates the development of atherosclerosis in mice through CD36 dependent-defective autophagy.

Caspase recruitment-domain containing protein 9 (CARD9) is a key signaling pathway in macrophages but its role in atherosclerosis is still poorly understood. Global deletion of Card9 in Apoe-/- mice as well as hematopoietic deletion in Ldlr-/- mice increases atherosclerosis. The acceleration of atherosclerosis is also observed in Apoe-/-Rag2-/-Card9-/- mice, ruling out a role for the adaptive immune system in the vascular phenotype of Card9 deficient mice. Card9 deficiency alters macrophage phenotype through CD36 overexpression with increased IL-1ß production, increased lipid uptake, higher cell death susceptibility and defective autophagy. Rapamycin or metformin, two autophagy inducers, abolish intracellular lipid overload, restore macrophage survival and autophagy flux in vitro and finally abolish the pro-atherogenic effects of Card9 deficiency in vivo. Transcriptomic analysis of human CARD9-deficient monocytes confirms the pathogenic signature identified in murine models. In summary, CARD9 is a key protective pathway in atherosclerosis, modulating macrophage CD36-dependent inflammatory responses, lipid uptake and autophagy.

Saccharomyces boulardii CNCM I-745 supplementation during and after antibiotic treatment positively influences the bacterial gut microbiota.

Introduction: Antibiotic effects on gut bacteria have been widely studied, but very little is known about the consequences of such treatments on the mycobiota, the fungal part of the microbiota and how the length of administration influences both microbiota. Here, we examined the effect of antibiotics (ATB) on the composition of bacterial and fungal microbiota and how the administration of Saccharomyces boulardii CNCM I-745 influences both microbiota. Methods: In order to get closer to the human microbiota, the mice used in this study were subjected to fecal microbiota transfer (FMT) using human feces and subsequently called human microbiotaassociated (HMA) mice. These mice were then treated with amoxicillinclavulanate antibiotics and supplemented with S. boulardii during and after ATB treatment to understand the effect of the yeast probiotic on both bacterial and fungal microbiota. Bacterial and fungal microbiota analyses were done using 16S and ITS2 rRNA amplicon-based sequencing. Results: We showed that the administration of S. boulardii during ATB treatment had very limited effect on the fungal populations on the long term, once the yeast probiotic has been cleared from the gut. Concerning bacterial microbiota, S. boulardii administration allowed a better recovery of bacterial populations after the end of the ATB treatment period. Additionally, 16S and ITS2 rRNA sequence analysis revealed that 7 additional days of S. boulardii administration (17 days in total) enhanced the return of the initial bacterial equilibrium. Discussion: In this study, we provide a comprehensive analysis of how probiotic yeast administration can influence the fungal and bacterial microbiota in a model of broad-spectrum antibiotherapy.