Regulating Microbiota Composition Research Articles

Paneth Cell-Specific TRPV6 Channel Plays a Crucial Role in Alcohol-Associated Dysbiosis of Gut Microbiota and Tissue Injury at the Gut-Liver Axis

Introduction: Endotoxemia plays an essential role in alcohol-associated tissue injury. Two factors contributing to endotoxemia are gut microbiota dysbiosis and epithelial barrier dysfunction. Previous studies indicated that TRPV6 channel-mediated Ca2+ influx plays a crucial role in alcohol-induced epithelial tight junction (TJ) disruption, mucosal barrier dysfunction, and endotoxemia. Trpv6 knockout mice were resistant to alcohol-induced intestinal barrier dysfunction and modulated microbiota dysbiosis, raising the question of how TRPV6 regulates microbiota composition. In this study, we investigated the role of Paneth cell-specific TRPV6 in alcohol-induced microbiota dysbiosis and barrier dysfunction. Methods: Adult Trpv6fl/fl (WT) and Trpv6fl/fl-Defa6Cre (KO; Paneth cell-specific TRPV6 knockout) mice were fed a Lieber-DiCarli liquid diet with EtOH (0% 2d, 1% 2d, 2% 2d, 4% 1wk, 5% 1wk, & 6% 1wk). Control groups were pair-fed an isocaloric EtOH-free diet. Intestinal permeability was measured by vascular-to-luminal flux of FITC-inulin in vivo, and mucosal inflammation was assessed by RT-PCR for cytokines/chemokines. Plasma lipopolysaccharide (LPS) was measured to evaluate endotoxemia. Gut microbiota was analyzed by 16S rRNA sequencing of colonic flushing. Lipidome in colonic flushing was analyzed using nontargeted liquid chromatography-mass spectrometry. Microbiome and lipidome data were processed by bioinformatic analyses. Results and conclusion: Data show that colon length was reduced, and colonic mucosal permeability in vivo was elevated by EtOH in WT mice. The increase in mucosal permeability was associated with increased plasma LPS levels. EtOH feeding elevated the expression of IL-6, IL-1β, and TNFα in the colon. EtOH-induced changes in colon length, mucosal permeability, cytokine expression, and plasma LPS were absent in KO mice. 16S rRNA sequencing data indicated that the microbiota composition in KO mice differed from that of WT mice. The relative abundance of Prevotellaceae, Xanthomonadaceae, and Streptococaceae were higher, and Psuedomonadaceae and Verrucomicrobiaceae abundance were lower in KO mice compared to WT mice. EtOH-induced increase in the abundance of Norcardiaceae and Psuedomonadaceae was low or absent in KO mice. EtOH increased Rhodococcus, Odoribacter, and Pseudomonas abundance at the genus level in WT but not KO mice. On the other hand, Clostridium, Turicibacter, and Helicobacter abundance were increased by EtOH in KO but not WT mice. Lipidomic analysis of colonic flushing showed that phospholipid contents were higher in KO mice than WT mice, irrespective of sex and treatments. A cluster of sphingolipids was dramatically high in KO female mice, which was reduced by EtOH feeding. Short-chain fatty acid esters of hydroxy fatty acids (AAHFA 3:0/24:0;O) were elevated by EtOH in male WT mice but not in female WT and male or female KO mice. In conclusion, these data indicate that Paneth cell-specific deletion of TRPV6 attenuates alcohol-induced changes in gut microbiota, colonic luminal lipids, mucosal barrier function, and endotoxemia in mice. NIH/NIAAA, RO1-AA029270; Veterans Administration IO1-BX003014. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

B-cell-specific MhcII regulates microbiota composition in a primarily IgA-independent manner.

The expression of major histocompatibility complex class II (MhcII) molecules on B cells is required for the development of germinal centers (GCs) in lymphoid follicles; the primary sites for the generation of T-cell-dependent (TD) antibody responses. Peyer's patches (PPs) are secondary lymphoid tissues (SLOs) in the small intestine (SI) that give rise to high-affinity, TD antibodies (mainly immunoglobulin A (IgA)) generated against the microbiota. While several studies have demonstrated that MhcII antigen presentation by other immune cells coordinate TD IgA responses and regulate microbiota composition, whether or not B-cell-specific MhcII influences gut microbial ecology is unknown. Here, we developed a novel Rag1 -/- adoptive co-transfer model to answer this question. In this model, Rag1 -/- mice were reconstituted with naïve CD4+ T cells and either MhcII-sufficient or MhcII-deficient naïve B cells. Subsequent to this, resulting shifts in microbiota composition was characterized via 16S rRNA gene sequencing of SI-resident and fecal bacterial communities. Results from our experiments indicate that SLO development and reconstitution of an anti-commensal TD IgA response can be induced in Rag1 -/- mice receiving T cells and MhcII-sufficient B cells, but not in mice receiving T cells and MhcII-deficient B cells. Results from our 16S experiments confirmed that adaptive immunity is a relevant host factor shaping microbial ecology in the gut, and that its impact was most pronounced on SI-resident bacterial communities. Our data also clearly establishes that MhcII-mediated cognate interactions between B cells and T cells regulates this effect by maintaining species richness in the gut, which is a phenotype commonly associated with good health. Finally, contrary to expectations, our experimental results indicate that IgA was not responsible for driving any of the effects on the microbiota ascribed to the loss of B cell-specific MhcII. Collectively, results from our experiments support that MhcII-mediated antigen presentation by B cells regulates microbiota composition and promotes species richness through an IgA-independent mechanism.

The Diversity of Gut Microbiota at Weaning Is Altered in Prolactin Receptor-Null Mice.

Maternal milk supports offspring development by providing microbiota, macronutrients, micronutrients, immune factors, and hormones. The hormone prolactin (PRL) is an important milk component with protective effects against metabolic diseases. Because maternal milk regulates microbiota composition and adequate microbiota protect against the development of metabolic diseases, we aimed to investigate whether PRL/PRL receptor signaling regulates gut microbiota composition in newborn mice at weaning. 16SrRNA sequencing of feces and bioinformatics analysis was performed to evaluate gut microbiota in PRL receptor-null mice (Prlr-KO) at weaning (postnatal day 21). The normalized colon and cecal weights were higher and lower, respectively, in the Prlr-KO mice relative to the wild-type mice (Prlr-WT). Relative abundances (Simpson Evenness Index), phylogenetic diversity, and bacterial concentrations were lower in the Prlr-KO mice. Eleven bacteria species out of 470 differed between the Prlr-KO and Prlr-WT mice, with two genera (Anaerotruncus and Lachnospiraceae) related to metabolic disease development being the most common in the Prlr-KO mice. A higher metabolism of terpenoids and polyketides was predicted in the Prlr-KO mice compared to the Prlr-WT mice, and these metabolites had antimicrobial properties and were present in microbe-associated pathogenicity. We concluded that the absence of the PRL receptor altered gut microbiota, resulting in lower abundance and richness, which could contribute to metabolic disease development.

Ulva prolifera Polysaccharide-Manganese Alleviates Inflammation and Regulates Microbiota Composition in Dextran Sulfate Sodium-Induced Colitis Mice.

Manganese (Mn) deficiency exacerbates colitis symptoms, whereas diet supplemented with inorganic Mn merely maintains colon length in experimental colitis. In the present study, a new form of Mn, Ulva prolifera polysaccharide cheated-Mn (PMn) was used and its treatment effects on dextran sulfate sodium (DSS)-induced colitis were investigated. Male C57BL/6 mice were orally administrated with 3.5% DSS to induce colitis. Then, the colitis mice were treated with PBS or PMn for 7 days. The results showed that PMn administration help retrieve the body weight loss and intestinal morphology damage, and alleviate apoptosis and inflammatory responses in colitis mice. Moreover, PMn administration decreased intestinal infiltration as indicated by decreased concentration of myeloperoxidase and eosinophil peroxidase. Importantly, PMn retrieved the increased abundance of Firmicutes and the decreased abundance of Bacteroidetes caused by DSS, suggested its beneficial roles in regulating microbiota composition in mice with colon inflammation. Gut microbiota composition at the genus level in the mice administrated with PMn was similar to those in control mice, whereas they were clearly distinct from DSS-treated mice. These results support the potential therapeutic role of PMn in the treatment of intestinal colitis and microbes may play critical roles in mediating its effects.

Fecal miR-142a-3p from dextran sulfate sodium-challenge recovered mice prevents colitis by promoting the growth of Lactobacillus reuteri

Feces are enriched with microRNAs (miRNAs) that shape the gut microbiota. These miRNAs are differentially expressed in the feces of healthy and diseased subjects. However, whether fecal miRNAs in subjects with inflammatory bowel diseases are involved in regulating microbiota composition and whether they have any beneficial effects remains unknown. Here, we studied the fecal microbiome composition and miRNA abundance in mice with dextran sulfate sodium (DSS)-induced colitis and mice at the recovery phase to explore different miRNAs expressed, their relations with microbial abundance, and their effects on colitis. We found that miR-142a-3p expression was significantly increased in the feces of mice recovered from colitis and that it could alleviate disease symptoms in mice treated with DSS in a microbiome-dependent manner. Specifically, miR-142a-3p promoted the growth of Lactobacillus reuteri, which had a high abundance in the feces of mice recovered from colitis, by regulating transcripts of polA and locus tag LREU_RS03575. Moreover, L.reuteri, as well as its metabolite reuterin, could alleviate DSS-induced disease symptoms. These results highlight the role of fecal miR-142a-3p in the prevention of colitis. We propose that the feces of subjects who have recovered from diseases might be enriched with miRNAs with preventive effects against those diseases.

Mutual interaction of microbiota and host immunity during health and diseases.

Microbiota-host interaction has attracted more and more attentions in recent years. The association between microbiota and host health is largely attributed to its influence on host immune system. Microbial-derived antigens and metabolites play a critical role in shaping the host immune system, including regulating its development, activation, and function. However, during various diseases the microbiota-host communication is frequently found to be disordered. In particular, gut microbiota dysbiosis associated with or led to the occurrence and progression of infectious diseases, autoimmune diseases, metabolic diseases, and neurological diseases. Pathogenic microbes and their metabolites disturb the protective function of immune system, and lead to disordered immune responses that usually correlate with disease exacerbation. In the other hand, the immune system also regulates microbiota composition to keep host homeostasis. Here, we will discuss the current advances of our knowledge about the interactions between microbiota and host immune system during health and diseases.

Spoilage-related microbiota in fish and crustaceans during storage: Research progress and future trends.

Fish and crustaceans are highly perishable due to microbial growth and metabolism. Recent studies found that the spoilage process of fish and crustaceans is highly related to their microbiota composition. Microbiota of fish and crustaceans changes dramatically during storage and can be influenced by many factors (e.g., aquaculture environment, handling process, storage temperature, and various quality control techniques). Among them, many quality control techniques have exhibited efficient effects on inhibiting spoilage bacteria, regulating microbiota composition, and retarding quality deterioration. In this article, we elucidate the relationship between microbiota composition and fish/crustacean spoilage, demonstrate influencing factors of fish/crustaceans microbiota, and review various quality control techniques (especially plant-derived preservatives) including their preservative effects on microbiota and quality of fish and crustaceans. Besides, present and future trends of various detective methods used in microbiota analysis are also compared in this review, so as to provide guides for future microbiota studies. To conclude, novel preservation techniques (especially plant-derived preservatives) and hurdle technologies are expected to achieve comprehensive inhibitory effects on spoilage bacteria. Efficient delivery systems are promising in improving the compatibility of plant-derived preservatives with fish/crustaceans and enhancing their preservative effects. Besides, spoilage mechanisms of fishery products that involve complex metabolisms and microbial interactions need to be further elucidated, by using omics technologies like metagenomics, metatranscriptomics, and metabolomics.

Microbiota-Mitochondria Inter-Talk: A Potential Therapeutic Strategy in Obesity and Type 2 Diabetes.

The rising prevalence of obesity and type 2 diabetes (T2D) is a growing concern worldwide. New discoveries in the field of metagenomics and clinical research have revealed that the gut microbiota plays a key role in these metabolic disorders. The mechanisms regulating microbiota composition are multifactorial and include resistance to stress, presence of pathogens, diet, cultural habits and general health conditions. Recent evidence has shed light on the influence of microbiota quality and diversity on mitochondrial functions. Of note, the gut microbiota has been shown to regulate crucial transcription factors, coactivators, as well as enzymes implicated in mitochondrial biogenesis and metabolism. Moreover, microbiota metabolites seem to interfere with mitochondrial oxidative/nitrosative stress and autophagosome formation, thus regulating the activation of the inflammasome and the production of inflammatory cytokines, key players in chronic metabolic disorders. This review focuses on the association between intestinal microbiota and mitochondrial function and examines the mechanisms that may be the key to their use as potential therapeutic strategies in obesity and T2D management.

Supplementation of lactobacilli improves growth, regulates microbiota composition and suppresses skeletal anomalies in juvenile pike-perch (Sander lucioperca) reared in recirculating aquaculture system (RAS): A pilot study

This research aimed to test the effects of lactobacilli, applied to cultured pike-perch, either through hydrolyzed OTOHIME fish diet, or through Artemia nauplii, on fish growth, microbiota balance and skeletal development. On the 12th Day Post Hatching (DPH) fish were divided into following treatment groups: two groups received the combination of OTOHIME and nauplii enriched either with Lactobacillus paracasei BGHN14+Lactobacillus rhamnosus BGT10 or with Lactobacillus reuteri BGGO6–55+Lactobacillus salivarius BGHO1, and one group received OTOHIME hydrolyzed by BGHN14+BGT10 and non-enriched nauplii. Control group received non-enriched nauplii and non-hydrolyzed OTOHIME. The treatment lasted 14days and fish were sacrificed on the 26th DPH for the assessment of digestive enzyme activity and microbiota composition. Individual total lengths and individual body weights were recorded at the end of the treatments, on the 26th DPH, and also on the 45th DPH, in parallel with the evaluation of skeletal deformities and fish survival. Our results indicated positive effect of Artemia enriched with BGGO6–55+BGHO1 on fish growth, skeletal development and trypsin to chymotrypsin activity ratio (T/C), as an indicator of protein digestibility. Hydrolysis of OTOHIME was also associated with better skeletal development, higher T/C values and lower levels of Aeromonas and Mycobacterium spp., which are important fish pathogens. Though additional testing in larger cohort studies is needed, these observations are promising in terms of usage of probiotics for improved environmentally friendly production of pike-perch in Recirculating Aquaculture System (RAS).

Do antibodies select a healthy microbiota?

Disruptions to the microbiota can have pathological consequences, which highlights the need to understand the factors that contribute to its stability. Although decades of research have focused on the importance of IgA during pathogenic infection, much of the IgA that is generated in the gut targets the resident commensal microorganisms. Despite this observation, the role of antibodies in regulating microbiota composition remains controversial and poorly understood. Here we propose that antibodies generated in response to microbial colonization of the gut shape the composition of the microbiota to benefit the health of the host through a process that we term antibody-mediated immunoselection (AMIS). Given the exquisite specificity of antibodies and an emerging interest in the use of immunotherapies, we suggest that understanding AMIS of the microbiota will highlight novel uses of antibodies to manipulate microbial communities for therapeutic benefit.

MyD88 signaling in T cells directs IgA-mediated control of the microbiota to promote health.

Altered commensal communities are associated with human disease. IgA mediates intestinal homeostasis and regulates microbiota composition. Intestinal IgA is produced at high levels as a result of T follicular helper cell (TFH) and B cell interactions in germinal centers. However, the pathways directing host IgA responses toward the microbiota remain unknown. Here, we report that signaling through the innate adaptor MyD88 in gut Tcells coordinates germinal center responses, including TFH and IgA+ B cell development. TFH development is deficient in germ-free mice and can be restored by feeding TLR2 agonists that activate Tcell-intrinsic MyD88 signaling. Loss of this pathway diminishes high-affinity IgA targeting of the microbiota and fails to control the bacterial community, leading to worsened disease. Our findings identify that Tcells converge innate and adaptive immune signals to coordinate IgA against the microbiota, constraining microbial community membership to promote symbiosis.

Coated zinc oxide improves intestinal immunity function and regulates microbiota composition in weaned piglets

The present study was conducted to test the hypothesis that low concentrations of coated ZnO, as a substitute for a high concentration of ZnO (2250 mg Zn/kg), could improve intestinal immunity function and regulate microbiota composition, thus alleviating the incidence of diarrhoea in weaned piglets. A total of eighty-four cross-bred piglets, weaned at an age of 28 (SEM 1) d, were allocated randomly, on the basis of average initial body weight (7·72 (SEM 0·65) kg), to seven treatment groups as follows: a 250 mg Zn (ZnO)/kg group (low Zn; LZ) and a 2250 mg Zn (ZnO)/kg group (high Zn; HZ) that were offered diets containing ZnO at 250 and 2250 mg Zn/kg, respectively; and five experimental groups in which coated ZnO was added at 250, 380, 570, 760 and 1140 mg Zn/kg basal diet, respectively. The trial lasted 2 weeks. The results indicated that, compared with LZ treatment, supplementation with coated ZnO at 380 or 570 mg Zn/kg reduced (P< 0·05) diarrhoea index, increased (P< 0·05) duodenal villus height and the ratio of villus height:crypt depth, up-regulated (P< 0·05) the gene expression of insulin-like growth factor 1, zonula occludens protein-1, occludin, IL-10 and transforming growth factor β1, and elevated (P< 0·05) secretory IgA concentration in the jejunal mucosa. Microbiota richness and the Shannon diversity index were also decreased (P< 0·05). Furthermore, piglets in the group fed coated ZnO at 380 or 570 mg Zn/kg did not differ from those in the HZ-fed group in relation to the aforementioned parameters. Collectively, a low concentration of coated ZnO (380 or 570 mg Zn/kg) can alleviate the incidence of diarrhoea by promoting intestinal development, protecting the intestinal mucosal barrier from damage, stimulating the mucosal immune system and regulating the microbiota composition.

Old Dog, New Trick: A Direct Role for Leptin in Regulating Microbiota Composition

he intestinal tract is the first barrier from the externaltotheinternalenvironment.Assuch,itplaysakeyrolenotonlyinnutrientabsorptionbutalsoinprotectionfromtoxinsandimmunity.However,thegutisnotaloneinthisregulatory role. The mammalian intestinal tract is colo-nized by trillions of microorganisms collectively referredto as the microbiome. These bacteria have a symbioticrelationship with the host and contribute to many vitalintestinalfunctions(1,2).Thesefunctionsincludehomeo-stasis of the immune system, including protection againstpathogens, intestinal cell development and proliferation,xenobiotic metabolism, bone mineral density, behavior,and metabolism (1, 2).That the gut microbiota plays a critical role in main-taining not only intestinal but also host homeostasis as awhole has been well described (3). Its role in disease hasbecomemoreapparentoverthelastseveralyearscoincid-ing with advances in technology that allow for compre-hensive high-throughput sequencing analysis of the mi-crobiome. Data suggest that shifting of the microbiotapopulationsaltersthebalanceofthemicrobiome(dysbio-sis), and this increases the risk of intestinal infection (4)and intestinal disorders such as irritable bowel syndromeandinflammatoryboweldisease(5).Moreover,dysbiosisis implicated in diseases thought to be unrelated to intes-tinal function, including cardiovascular disease (6), obe-sity (2, 7), diabetes (8), autism (9), and even cancer (5).Conversely,correctionofdysbiosisisalsothoughttobeamechanism for the drastic weight loss and metabolic im-provements seen with bariatric surgery (10).Given the wide-ranging implications for alterations inthe microbiota, determining what regulates their differ-entiation is critical but, at present, is not completely un-derstood.Variationofthemicrobiotaisinfluencedinformor function by the introduction of probiotics (11), antibi-otics(12),anddiet(13)aswellasdevelopmentandaging(5), altogether demonstrating the role of the environmentinregulatingmicrobiomecomposition.Althoughgeneticsdoes play a role (14), internal pressures dictated by hostphysiology also influence the local colonization. Panethcells, which are secretory epithelial cells, regulate devel-opment of the barrier between intestinal microbes andmucosalepithelialcellsandalsosecreteantimicrobialpep-tides (15), gene-encoded antibiotics (16). Antimicrobialpeptides, in turn, target intruding pathogens but also res-identmicrobiotaofthesmallintestine(17,18),thusshap-ingthecompositionofthemicrobiota.Understandingreg-ulationofPanethcellsand/orantimicrobialpeptidescouldprovideanewpipelinefortherapeutictargetingofawiderange of chronic diseases.Anewstudyinthisissueof

Regulation of Microbial Populations and Immune Functions by Muc5b

The MUC5AC and MUC5B genes encode mucin glycoproteins that are structurally similar and are the principal macromolecules in airway mucus. In spite of its beneficial function, mucus overproduction, hypersecretion, and accumulation are associated with chronic lung diseases and have emerged as attractive therapeutic targets. However, specific roles of MUC5AC and MUC5B in mucociliary clearance (MCC), and the lasting effects of their inhibition, are unknown. Here, using two mouse lines lacking Muc5ac and Muc5b, we show that whereas Muc5ac is dispensable at baseline, Muc5b is required for normal respiratory function, MCC, and survival. Strikingly, in addition to acutely controlling particle elimination, Muc5b is also crucial for maintaining homeostatic microbial composition and innate immune responsiveness. We found that Muc5b (but not Muc5ac) deficiency caused a significant increase in culturable bacteria in the lungs. This was marked by a significant shift in the diversity of cultured organisms—notably characterized by the acquisition of Staphylococcus aureus. Thus, Muc5b is essential for controlling homeostatic and pathological microbial populations in the lungs. Because MUC5B is reduced in asthma and chronic obstructive pulmonary disease, Muc5b-deficient mice provide a useful basis for establishing the nature of host–environment interactions in regulating microbiota composition. Recent work from our laboratory focuses on how Muc5b expression controls microbiome composition and function at baseline and in response to chronic inflammation. At baseline, loss of Muc5b is compensated for by macrophage-mediated clearance and innate type 17 immune responses. However, chronic loss of Muc5b causes a 50% reduction in macrophage phagocytosis and a greater than 95% reduction in IL-23. These studies identify mechanisms by which Muc5b regulates barrier and immune functions in the lungs, and they demonstrate that Muc5ac and Muc5b serve distinct and specific roles in the airways. Our results also provide a framework for designing targeted therapies to reduce mucus hypersecretion and enhance MCC in chronic lung diseases.

Diversity of intestinal microbiota in infancy and the risk of allergic disease in childhood

Numerous studies have attempted to describe specific microbiota deviations that may precede atopic sensitization and atopic disease in childhood. This has given rise to a hypothesis suggesting that a reduced intestinal microbial diversity in infancy increases the risk of allergic manifestations. This review intends to sum up the main findings and discuss relevant exposures that regulate intestinal microbial diversity. Taken together the three studies in this review lend support to the diversity hypothesis, but reported differences related to atopic sensitization and clinical expression are discussed. A summary on analytic methods and functional aspect of the microbiota in allergic disease is presented to ameliorate a presentation of recent articles on environmental and host-factors regulating microbiota composition and diversity. The current evidence indicates that intestinal microbiota diversity can be associated with allergic diseases, but the exact mechanisms and interactions contributing to this effect are far from understood and need further investigation.