Gut Immunity Research Articles

Dietary salt, vascular dysfunction, and cognitive impairment.

Excessive salt consumption is a major health problem worldwide leading to serious cardiovascular events including hypertension, heart disease and stroke. Additionally, high salt diet has been increasingly associated with cognitive impairment in animal models and late-life dementia in humans. High salt consumption is harmful for the cerebral vasculature, disrupts blood supply to the brain and could contribute to Alzheimer's disease pathology. Although animal models have advanced our understanding of the cellular and molecular mechanisms, additional studies are needed to further elucidate the effects of salt on brain function. Furthermore, the association between excessive salt intake and cognitive impairment will have to be more thoroughly investigated in humans. Since the harmful effects of salt on the brain are independent by its effect on blood pressure, in this review, I will specifically discuss the evidence, available in experimental models and humans, on the effects of salt on vascular and cognitive function in the absence of changes in blood pressure. Given the strong effects of salt on the function of immune cells, I will also discuss the evidence linking salt consumption to gut immunity dysregulation with particular attention to the ability of salt to disrupt T-helper 17 (Th17) cells homeostasis. Lastly, I will briefly discuss the data implicating IL-17A, the major cytokine produced by Th17 cells, in vascular dysfunction and cognitive impairment.

Responses of Intestinal Antioxidant Capacity, Morphology, Barrier Function, Immunity, and Microbial Diversity to Chlorogenic Acid in Late-Peak Laying Hens.

This study examined the influence of chlorogenic acid (CGA) on gut antioxidant status, morphology, barrier function, immunity, and cecal microbiota in late-peak laying hens. A total of 240 Hy-Line Brown hens, aged 43 weeks, were randomly assigned to four groups, the basal diet +0, 400, 600, and 800 mg/kg CGA, for 12 weeks. The results revealed that CGA significantly reduced ileal H2O2 and malondialdehyde levels; increased duodenal height, ileal villus height, and villus height-to-crypt depth ratio; while decreasing jejunal crypt depth. The 600 and 800 mg/kg CGA significantly upregulated the duodenal, jejunal, and ileal ZO-1 and occludin gene expression; increased IgG levels in serum and ileum; and upregulated ileal IgA gene expression. The 600 mg/kg CGA significantly upregulated CD3D and CD4 gene expression, while downregulating IL-1β gene expression in duodenum, jejunum, and ileum. Moreover, CGA changed the gut microbiota structure. The SCFA-producing bacteria unclassified_f__Peptostreptococcaceae, unclassified_f_Oscillospiraceae, Pseudoflavonifractor, Lachnospiraceae_FCS020_group, Oscillospira, Elusimicrobium, Eubacterium_ventriosum_group, Intestinimonas, and norank_f_Coriobacteriales_Incertae_Sedis were significantly enriched in the 400, 600, and/or 800 mg/kg CGA groups. The bacteria Lactobacillus, Bacillus, and Akkermansia were significantly enriched in the 600 mg/kg CGA group. Conclusively, dietary CGA (600-800 mg/kg) improved intestinal antioxidant status, morphology, barrier and immune function, and beneficial microbiota growth in late-peak laying hens.

Gut microbiota and immunity in health and diseases: a review

Gut microbiota and immunity in health and diseases: a review

Postnatal supplementation with alarmins S100a8/a9 ameliorates malnutrition-induced neonate enteropathy in mice.

Malnutrition is linked to 45% of global childhood mortality, however, the impact of maternal malnutrition on the child's health remains elusive. Previous studies suggested that maternal malnutrition does not affect breast milk composition. Yet, malnourished children often develop a so-called environmental enteropathy, assumed to be triggered by frequent pathogen uptake and unfavorable gut colonization. Here, we show in a murine model that maternal malnutrition induces a persistent inflammatory gut dysfunction in the offspring that establishes during nursing and does not recover after weaning onto standard diet. Early intestinal influx of neutrophils, impaired postnatal development of gut-regulatory functions, and expansion of Enterobacteriaceae were hallmarks of this enteropathy. This gut phenotype resembled those developing under deficient S100a8/a9-supply via breast milk, which is a known key factor for the postnatal development of gut homeostasis. We could confirm that S100a8/a9 is lacking in the breast milk of malnourished mothers and the offspring's intestine. Nutritional supply of S100a8 to neonates of malnourished mothers abrogated the aberrant development of gut mucosal immunity and microbiota colonization and protected them lifelong against severe enteric infections and non-infectious bowel diseases. S100a8 supplementation after birth might be a promising measure to counteract deleterious imprinting of gut immunity by maternal malnutrition.

Global hotspots and trends in gut mycological research: a visual analytics and bibliometric approach.

Recent findings highlight the significant impact of intestinal fungi on the complex makeup of the gut microbiota and human health, challenging past oversights. However, a lack of thorough systematic and quantitative analyses remains. This study aims to address this gap by thoroughly examining the current research on gut fungi. Through analyzing developments and unique features in this area, our goal is to foster a deeper understanding and identify future research pathways. We performed an extensive bibliometric analysis on documents from 2000 to 2023, sourced from the Web of Science Core Collection (WoSCC). Utilizing advanced visualization tools such as VOSviewer, CiteSpace, and Bibliometrix R, we meticulously examined and illustrated the data in scientific landscapes and networks. A total of 1434 papers were analyzed, revealing a substantial increase in publication volume over the past two decades, particularly in 2020. Contributions came from 67 countries, 2178 institutions, and 8,479 authors. China led in publication output with 468 articles, followed by the University of California with 84 articles, and ZHANG F as the most prolific author with 17 articles. Emerging research areas such as "Fungal-Bacteria Interactions," "Gut Fungus and Gut-Brain Axis," and "Gut Fungus and Immunity" are expected to attract growing interest in the future. This extensive bibliometric analysis offers a current overview of scholarly efforts concerning intestinal fungi, highlighting the predominant landscape in this field. These insights can assist scholars in identifying appropriate publication avenues, forming collaborative relationships, and enhancing understanding of key themes and emerging areas, thereby stimulating future research endeavors.

Garlic Bioconverted by Bacillus subtilis Stimulates the Intestinal Immune System and Modulates Gut Microbiota Composition.

This study evaluates the potential of bioconverted garlic ferments (BGFs) to stimulate the intestinal immune system and modulate cecal microbiota composition. In vitro, BGF significantly enhances Peyer's patch (PP)-mediated bone marrow cell proliferation and increases the production of interferon-gamma (IFN-γ), granulocyte macrophage-colony stimulating factor (GM-CSF), interleukin (IL)-6, and immunoglobulin A (IgA) but not IL-4, IL-5, and immunoglobulin E (IgE). Oral administration of BGF to C3H/HeN mice for 4 weeks significantly increases the GM-CSF (42.1-45.8 pgmL-1) and IFN-γ (6.5-12.1 pgmL-1) levels in PP cells. BGF also significantly elevates the levels of tumor necrosis factor-alpha (TNF-α, 165.0-236.3 pgmg-1), GM-CSF (2.4-3.0ngmg-1), and IFN-γ (1.5-3.2ngmg-1) in the small intestinal fluid, and TNF-α (2.2-3.1 pgmL-1) and IFN-γ (10.3-0.21.5 pgmL-1) in the mouse serum. Cecal microbial analysis reveals that BGF increases Bacteroidota and Verrucomicrobiota and decreases Actinobacteria and Bacillota at the phylum level in mice. At the genus level, BGF significantly increases the abundance of Fusimonas (250mgkg-1BW-1day-1), Bacteroides (125 and 250mgkg-1BW-1day-1), and Akkermansia (125mgkg-1BW-1day-1) and decreases that of Bifidobacterium (62.5 and 250mgkg-1BW-1day-1) and Limosilactobacillus (125 and 250mgkg-1BW-1day-1). This study provides the first evidence of BGF's ability to modulate the intestinal immune system and gut microbiota, supporting its potential as a novel functional material to enhance gut immunity.

Gut dysbiosis as a susceptibility factor in childhood idiopathic nephrotic syndrome

Idiopathic nephrotic syndrome (INS) is a relatively common renal disorder of childhood characterized by severe proteinuria and associated hypoproteinemia and edema. Although the pathogenesis of INS remains unknown, the prevailing theory of its pathogenesis is as follows. Antigenic stimulation, such as viral infections or vaccines, in children with susceptibility factors for INS triggers abnormal immune responses, resulting in production of pathogenic substances that injure podocytes (renal glomerular epithelial cells). The injured podocytes then change their function and morphology, resulting in increased permeability of plasma proteins. Consequently, plasma proteins, especially albumin, are leaked into urine and massive proteinuria ensues. Research on susceptibility factors for INS has focused on polymorphisms in several genes including human leukocyte antigen class II genes. However, we propose that dysbiosis of the intestinal microbiota could be a susceptibility factor for relapse. This proposal is based on our research group finding that children with INS and frequent relapses have gut dysbiosis characterized by a decreased proportion of beneficial bacteria such as short-chain fatty acid-producing bacteria. Dysbiosis from the neonatal period to infancy may result from environmental factors, such as cesarean section delivery and antibiotic administration, which prevent the establishment of a normal intestinal microbiota. Dysbiosis leads to aberrant gut immunity and is characterized by a decreased ratio of T helper 1 cells/T helper 2 cells and an increased ratio of T helper 17 cells/regulatory T-cells. Therefore, relapse occurs when immunologically pathogenic factors that injure podocytes are produced in response to trigger events in children with INS and gut dysbiosis. Our recent clinical trial suggested that long-term oral administration of butyric acid-producing bacterium as a probiotic is promising for suppressing relapse. Therefore, studying the causal relationship between dysbiosis and relapses in patients with INS in a larger number of patients is necessary.

Progranulin protects against Clostridioides difficile infection by enhancing IL-22 production

ABSTRACT Enhanced mortality, relapse rates, and increased prevalence of Clostridioides difficile infection (CDI) emphasize the need for better therapies and management approaches. Modulating host immune response to ameliorate CDI-associated immunopathology may provide new advantages to currently inadequate antibiotic therapies. Here, we identified progranulin (PGRN) as an important immune target upregulated in response to CDI. PGRN-deficient mice displayed dramatically higher mortality and aggravated epithelial barrier disruption compared with wild type (WT) mice after CDI despite equivalent levels of bacterial burden or toxin in the large intestine. Mechanistically, PGRN protection was mediated by IL-22 production from CD4+ T helper cells, as demonstrated by a decrease in colonic IL-22-producing CD4+ T helper cells in the intestine of PGRN-deficient mice upon CDI and a boost of IL-22-producing CD4+ T helper cells activated by PGRN ex vivo. Clinical evidence suggests that CDI patients had significantly higher serum levels of PGRN compared with healthy controls, which was significantly and positively correlated with IL-22. Our findings thus indicate a critical role for PGRN-promoted CD4+ T cell IL-22 production in shaping gut immunity and reestablishing the intestinal barrier during CDI. As an alternative to pathogen-targeted therapy, this study may provide a new host-directed therapeutic strategy to attenuate severe, refractory CDI.

Identification of Key Genes in Fetal Gut Development at Single-Cell Level by Exploiting Machine Learning Techniques.

The study of fetal gut development is critical due to its substantial influence on immediate neonatal and long-term adult health. Current research largely focuses on microbiome colonization, gut immunity, and barrier function, alongside the impact of external factors on these phenomena. Limited research has been dedicated to the categorization of developing fetal gut cells. Our study aimed to enhance our understanding of fetal gut development by employing advanced machine-learning techniques on single-cell sequencing data. This dataset consisted of 62,849 samples, each characterized by 33,694 distinct gene features. Four feature ranking algorithms were utilized to sort features according to their significance, resulting in four feature lists. Then, these lists were fed into an incremental feature selection method to extract essential genes, classification rules, and build efficient classifiers. Several important genes were recognized by multiple feature ranking algorithms, such as FGG, MDK, RBP1, RBP2, IGFBP7, and SPON2. These features were key in differentiating specific developing intestinal cells, including epithelial, immune, mesenchymal, and vasculature cells of the colon, duo jejunum, and ileum cells. The classification rules showed special gene expression patterns on some intestinal cell types and the efficient classifiers can be useful tools for identifying intestinal cells.

46 Feeding the weaned pig gut and beyond with non-nutritional additives

Abstract Weaning imposes simultaneous stress, resulting in reduced growth performance, increased susceptibility to diseases, and increased morbidity and mortality in weaned pigs. Weaning stress can induce negative changes in the intestine, including damaged intestinal integrity, disturbed digestive and absorptive capacity, increased intestinal oxidative stress, and microbial dysbiosis. Improving intestinal development and health is critically important for enhancing disease resistance and overall health of weaned pigs. This, in turn, can increase their survival rate during this vulnerable stage and improve their productive performance in later stages. A healthy gut may include, but is not limited to, several important features: a healthy proliferation of intestinal epithelial cells, an integrated gut barrier function, a preferable or balanced gut microbiota, and well-developed intestinal mucosa immunity. Burgeoning evidence suggests that many non-nutritional additives can enhance overall intestinal health and beyond by targeting one or several functions of the gut. However, the exact protective mechanisms may vary and are still not completely understood. For example, direct-fed microbials may confer health benefits on the host by producing antimicrobial products, regulating gut microbial profile or immunity, and/or enhancing gut barrier function. Non-digestible carbohydrates and prebiotics exhibit striking impacts on reshaping the composition of gut microbiota in the host by boosting the production of health-promoting bacteria. Phytochemicals, a large variety of secondary plant metabolites, have been known for their broad and promising biological properties, including anti-microbial, antioxidant, and immune-modulating activities. Several short chain fatty acids derivatives aim to target the upper gastrointestinal tract, where the major nutrients are digested and absorbed, to promote intestinal health of pigs. Moreover, butyrate and valerate glycerides exhibit strong in vitro antimicrobial effects against enterotoxigenic Escherichia coli F18, one of the dominant pathogens causing post-weaning diarrhea globally. There are more candidates in the list that have been used in weaned pigs and shown promising results on growth and health promotion. Therefore, increasing our current understanding of non-nutritional additives and their influences on intestinal function during weaning will facilitate the development of more dietary strategies that increase stress resilience of weaned pigs.

235 Impact of yeast cell wall and probiotics on gut microbiota, immunity, and growth in weaned piglets

Abstract This study investigates the effect of yeast cell wall (YCW) supplementation and multispecies probiotics as alternatives to antibiotic growth promoters (AGPs) on the gut microbiota, immune function, and growth performance in weaned piglets. We utilized a randomized complete block design involving 160 piglets across four treatments during the nursery phase. The treatments administered throughout the experimental period were as follows: CONT+ = basal diet with Halquinol (AGP); YCW = basal diet with Saccharomyces cerevisiae yeast cell wall at 1 kg/MT; SIM+ = basal diet with YCW at 0.5 kg/MT + multispecies probiotic (Bacillus subtilis 2.0 x 10^9 CFU/g, Bacillus coagulans 5.0 x 10^8 CFU/g, Clostridium butyricum 5.0 x 10^7 CFU/g, and Bacillus licheniformis 2.0 x 10^9 CFU/g) at 0.6 kg/MT; SIM- = basal diet with YCW at 0.5 kg/MT + multispecies probiotic at 0.3 kg/MT. Methodologies include daily feed intake, body weight gain measurement, feed conversion ratio (FCR), diarrhea scoring, serum cytokine and chemokine concentration, and microbiome analysis. Throughout the study period (21 to 63 d), only FCR showed differences (P = 0.0076). CONT+ and YCW demonstrated better FCRs, at 1.543 and 1.585 respectively, without significant variation between them, while SIM- lagged with the least favorable outcome at 1.654 (Table 1). At 35 d, IL-10 concentrations were greatest in the SIM- group, showing a 271.25% increase compared with other treatments (Figure 2). At 49 d, IL-8 was least in the YCW group, with a 247% reduction compared with CONT+, while SIM+ and SIM- showed no significant differences compared with other treatments (Figure 1). The Firmicutes/Bacteroidota (F/B) ratio shows that the CONT+ treatment was inferior compared with the YCW, SIM+, and SIM- treatments (Figure 3). The Lactobacillaceae family differed between CONT+ and the YCW, SIM+, and SIM- treatments, with the greatest abundance in the SIM+ treatment, followed by SIM- and YCW (Figure 4). The genera Lactobacillus differed between the CONT+ treatment compared with the YCW, SIM+, and SIM- treatments. Prebiotics, whether used alone or combined with probiotics, serve as effective substitutes for AGPs, boosting the health and performance of piglets throughout the nursery phase.

Effect of β-Alanine Metabolite on Gut Integrity and Immunity in Commercial Broiler Chickens Infected with Eimeria maxima.

(1) Background: In a metabolomics analysis conducted to investigate the mechanisms behind the growth-promoting effects of probiotics in broilers, β-alanine was found to be significantly elevated. This led to the hypothesis that β-alanine could also contribute to growth-promoting effects in infected broilers. (2) Methods: An in vitro culture system was developed to assess β-alanine's impact on proinflammatory cytokine response in chicken macrophage cells, gut integrity in chicken intestinal epithelial cells, and muscle differentiation in quail muscle cells and primary chicken embryonic muscle cells. In vivo animal feeding studies were then conducted to investigate the effects of dietary β-alanine on various disease parameters in Eimeria maxima-infected broiler chickens. (3) Results: In vitro, β-alanine treatment significantly decreased the gene expression of cytokines in chicken macrophage cells and increased occuldin expression in chicken intestinal epithelial cells. Dietary β-alanine increased the body weight of chickens following Eimeria maxima infection in the H-ALA group. Dietary β-alanine also suppressed cytokines and increased JAM-2 and occludin expression in the H-ALA group compared to the infected group without β-alanine supplementation. (4) Conclusions: These results strongly support the positive effects of dietary β-alanine on intestinal immune responses and gut barrier function in broiler chickens infected with Eimeria maxima.

Bile Acids and Liver Cancer: Molecular Mechanism and Therapeutic Prospects.

Hepatocellular carcinoma (HCC) is a highly aggressive liver malignancy and one of the most lethal cancers globally, with limited effective therapeutic options. Bile acids (BAs), as primary metabolites of hepatic cholesterol, undergo enterohepatic circulation involving secretion into the intestine and reabsorption into the liver, and their composition is modulated in this process. Recent clinical observations have revealed a correlation between alteration in the BAs profile and HCC incidence, and the effect of various species of BAs on HCC development has been investigated. The regulatory effect of different BA species on cell proliferation, migration, and apoptosis in tumor cells, as well as their interaction with gut microbiota, inflammation, and immunity have been identified to be involved in HCC progression. In this review, we summarize the current understanding of the diverse functions of BAs in HCC pathogenesis and therapy, from elucidating the fundamental mechanisms underlying both tumor-promoting and tumor-suppressive consequences of various BA species to exploring potential strategies for leveraging BAs for HCC therapy. We also discuss ongoing efforts to target specific BA species in HCC treatment while highlighting new frontiers in BA biology that may inspire further exploration regarding their connection to HCC.

L-Theanine Alleviates Ulcerative Colitis by Regulating Colon Immunity via the Gut Microbiota in an MHC-II-Dependent Manner.

Alterations to the gut microbiota are associated with ulcerative colitis (UC), whereas restoration of normobiosis can effectively alleviate UC. l-Theanine has been shown to reshape the gut microbiota and regulate gut immunity. To investigate the mechanisms by which l-theanine alleviates UC, we used l-theanine and l-theanine fecal microbiota solution to treat UC mice. In this study, we used l-theanine and l-theanine fecal microbiota solution to treat UC mice to explore the mechanism by which l-theanine alleviates UC. By reducing inflammation in the colon, we demonstrated that l-theanine alleviates symptoms of UC. Meanwhile, l-theanine can improve the abundance of microbiota related to short-chain fatty acid, bile acid, and tryptophan production. Single-cell sequencing results indicated that l-theanine-mediated suppression of UC was associated with immune cell changes, especially regarding macrophages and T and B cells, and validated the immune cell responses to the gut microbiota. Further, flow cytometry results showed that the ability of dendritic cells, macrophages, and monocytes to present microbiota antigens to colonic T cells in an MHC-II-dependent manner was reduced after treating normal mouse fecal donors with l-theanine. These results demonstrate that l-theanine modulates colon adaptive and innate immunity by regulating the gut microbiota in an MHC-II-dependent manner, thereby alleviating UC.

Sirtuin 6 inhibits group 3 innate lymphoid cell function and gut immunity by suppressing IL-22 production.

Group 3 innate lymphoid cells (ILC3s) are enriched in the intestinal mucosa and play important roles in host defense against infection and inflammatory diseases. Sirtuin 6 (SIRT6) is a nicotinamide adenine dinucleotide (NAD+)- dependent deacetylase and has been shown to control intestinal epithelial cell differentiation and survival. However, the role of SIRT6 in ILC3s remains unknown. To investigate the role of SIRT6 in gut ILC3s, we generated SIRT6 conditional knockout mice by crossing Rorccre and Sirt6flox/flox mice. Cell number and cytokine production was examined using flow cytometry. Citrobacter rodentium infection and dextran sodium sulfate-induced colitis models were used to determine the role of SIRT6 in gut defense. RT-qPCR, flow cytometry and immunohistochemistry were used to assess the intestinal inflammatory responses. Here we show that SIRT6 inhibits IL-22 expression in intestinal ILC3s in a cell-intrinsic manner. Deletion of SIRT6 in ILC3s does not affect the cell numbers of total ILC3s and subsets, but results in increased IL-22 production. Furthermore, ablation of SIRT6 in ILC3s protects mice against Citrobacter rodentium infection and dextran sodium sulfate-induced colitis. Our results suggest that SIRT6 may play a role in ILC3 function by regulating gut immune responses against bacterial infection and inflammation. Our finding provided insight into the relation of epigenetic regulators with IL-22 production and supplied a new perspective for a potential strategy against inflammatory bowel disease.

Diet-Induced Obesity in Mice Affects the Maternal Gut Microbiota and Immune Response in Mid-Pregnancy.

Maternal obesity during pregnancy is associated with adverse pregnancy outcomes. This might be due to undesired obesity-induced changes in the maternal gut microbiota and related changes in the maternal immune adaptations during pregnancy. The current study examines how obesity affects gut microbiota and immunity in pregnant obese and lean mice during mid-pregnancy (gestational day 12 (GD12)). C57BL/6 mice were fed a high-fat diet or low-fat diet from 8 weeks before mating and during pregnancy. At GD12, we analyzed the gut microbiota composition in the feces and immune responses in the intestine (Peyer's patches, mesenteric lymph nodes) and the peripheral circulation (spleen and peripheral blood). Maternal obesity reduced beneficial bacteria (e.g., Bifidobacterium and Akkermansia) and changed intestinal and peripheral immune responses (e.g., dendritic cells, Th1/Th2/Th17/Treg axis, monocytes). Numerous correlations were found between obesity-associated bacterial genera and intestinal/peripheral immune anomalies. This study shows that maternal obesity impacts the abundance of specific bacterial gut genera as compared to lean mice and deranges maternal intestinal immune responses that subsequently change peripheral maternal immune responses in mid-pregnancy. Our findings underscore the opportunities for early intervention strategies targeting maternal obesity, ideally starting in the periconceptional period, to mitigate these obesity-related pregnancy effects.

Stress-sensitive neural circuits change the gut microbiome via duodenal glands

Negative psychological states impact immunity by altering the gut microbiome. However, the relationship between brain states and microbiome composition remains unclear. We show that Brunner's glands in the duodenum couple stress-sensitive brain circuits to bacterial homeostasis. Brunner's glands mediated the enrichment of gut Lactobacillus species in response to vagus nerve stimulation. Cell-specific ablation of the glands markedly suppressed Lactobacilli counts and heightened vulnerability to infection. In the forebrain, we mapped a vagally mediated, polysynaptic circuit connecting the central nucleus of the amygdala to Brunner's glands. Chronic stress suppressed central amygdala activity and phenocopied the effects of gland lesions. Conversely, excitation of either the central amygdala or parasympathetic vagal neurons activated Brunner's glands and reversed the effects of stress on the gut microbiome and immunity. The findings revealed a tractable brain-body mechanism linking psychological states to host defense.

Growth performance, mucosal immunity and disease resistance in goldfish (Carassius auratus) orally administered with Escherichia coli Strain Nissle 1917.

The current research aimed to shed light on the efficacy of Escherichia coli strain Nissle 1917 (EcN) on goldfish (……) growth, gut immunity, morphology, bacterial nutritional enzyme activity and resistance to Aeromonas hydrophila infection. Fish fed with EcN at 106, 107 and 108CFU/g feed for 80days showed an enhancement in growth better than control fish. The gut innate immunity in terms of lysozyme activity, immunoglobulin and total protein levels was increased in the treatment fish with the best result being observed in fish fed EcN at 108CFU/ g. In addition, an increase was noted in the upregulation of immune-relevant genes, namely lysozyme, interleukin-1β, inducible nitric oxide synthase and tumor necrosis factor α of fish intestine. A marked surge in the number of proteolytic and heterotrophic bacteria was noted in the gut of fish nourished with the probiotic. Histological studies exhibited an improvement in the intestinal absorption surface area, intraepithelial lymphocyte count and goblet cell density. Significantly higher survival rate was obtained in fish fed EcN at 108CFU/g compared with the fish fed with the basal diet. These data exhibited the beneficial effect of EcN on goldfish growth, digestive enzymes, intestine heterotrophic bacteria and resistance against Aeromonas hydrophila challenge. This study confirmed the favorable outcomes resulting from the administration of EcN at108 CFU/g.

A suite of selective pressures supports the maintenance of alleles of a Drosophila immune peptide.

The innate immune system provides hosts with a crucial first line of defense against pathogens. While immune genes are often among the fastest evolving genes in the genome, in Drosophila , antimicrobial peptides (AMPs) are notable exceptions. Instead, AMPs may be under balancing selection, such that over evolutionary timescales multiple alleles are maintained in populations. In this study, we focus on the Drosophila antimicrobial peptide Diptericin A, which has a segregating amino acid polymorphism associated with differential survival after infection with the Gram-negative bacteria Providencia rettgeri . Diptericin A also helps control opportunistic gut infections by common Drosophila gut microbes, especially those of Lactobacillus plantarum . In addition to genotypic effects on gut immunity, we also see strong sex-specific effects that are most prominent in flies without functional diptericin A . To further characterize differences in microbiomes between different diptericin genotypes, we used 16S metagenomics to look at the microbiome composition. We used both lab reared and wild caught flies for our sequencing and looked at overall composition as well as the differential abundance of individual bacterial families. Overall, we find flies that are homozygous for one allele of diptericin A are better equipped to survive a systemic infection from P. rettgeri , but in general have a shorter lifespans after being fed common gut commensals. Our results suggest a possible mechanism for the maintenance of genetic variation of diptericin A through the complex interactions of sex, systemic immunity, and the maintenance of the gut microbiome.

Exploring the relationship between gut microbial ecology and inflammatory disease: An insight into health and immune function

The immune system, host brain development, and general metabolism are all influenced by the gut bacteria. Bacteria make up the majority of the gut microbiota in mammals. The mouse has been the most often used animal model in preclinical biological research. In mice, Firmicutes and Clostridiales are prominent. On the other hand, Bacteroidaceae , Prevotellaceae , and Firmicutes are commonly found in humans. In this review, we performed a detailed study by focusing on a comparison between human and murine gut microbiomes, role of the microbiome and their secreted metabolites in regulating gut immunity to maintain homeostasis, and changes in the microbial composition in the dysbiotic state.