Alterations In Intestinal Barrier Function Research Articles

Differential Modulation of Mouse Intestinal Organoids with Fecal Luminal Factors from Obese, Allergic, Asthmatic Children.

Asthma is a multifactorial condition that can be associated with obesity. The phenotypes of asthma in lean and obese patients are different, with proinflammatory signatures being further elevated in the latter. Both obesity and asthma are associated with alterations in intestinal barrier function and immunity, and with the composition of the intestinal microbiota and food consumption. In this study, we aimed to establish an organoid model to test the hypothesis that the intestinal content of lean and obese, allergic, asthmatic children differentially regulates epithelial intestinal gene expression. A model of mouse jejunum intestinal organoids was used. A group of healthy, normal-weight children was used as a control. The intestinal content of asthmatic obese children differentially induced the expression of inflammatory and mitochondrial response genes (Tnf-tumor necrosis factor, Cd14, Muc13-mucin 13, Tff2-Trefoil factor 2 and Tff3, Cldn1-claudin 1 and 5, Reg3g-regenerating family member 3 gamma, mt-Nd1-NADH dehydrogenase 1 and 6, and mt-Cyb-mitochondrial cytochrome b) via the RAGE-advanced glycosylation end product-specific receptor, NF-κB-nuclear factor kappa b and AKT kinase signal transduction pathways. Fecal homogenates from asthmatic normal-weight and obese children induce a differential phenotype in intestinal organoids, in which the presence of obesity plays a major role.

The protective effect of the intestinal microbiota in type-1 diabetes in NOD mice is limited to a time window in early life.

The incidence of type-1 diabetes is on the rise, particularly in developed nations, and predominantly affects the youth. While genetic predisposition plays a substantial role, environmental factors, including alterations in the gut microbiota, are increasingly recognized as significant contributors to the disease. In this study, we utilized germ-free non-obese diabetic mice to explore the effects of microbiota colonization during early life on type-1 diabetes susceptibility. Our findings reveal that microbiota introduction at birth, rather than at weaning, significantly reduces the risk of type-1 diabetes, indicating a crucial window for microbiota-mediated modulation of immune responses. This protective effect was independent of alterations in intestinal barrier function but correlated with testosterone levels in male mice. Additionally, early life colonization modulated T cell subset frequencies, particularly T helper cells and regulatory T cells, in the intestine, potentially shaping type-1 diabetes predisposition. Our findings underscore the pivotal role of early-life microbial interactions in immune regulation and the development of autoimmune diseases.

Cognitive Alterations in Old Mice Are Associated with Intestinal Barrier Dysfunction and Induced Toll-like Receptor 2 and 4 Signaling in Different Brain Regions.

Emerging evidence implicate the 'microbiota-gut-brain axis' in cognitive aging and neuroinflammation; however, underlying mechanisms still remain to be elucidated. Here, we assessed if potential alterations in intestinal barrier function and microbiota composition as well as levels of two key pattern-recognition receptors namely Toll-like receptor (TLR) 2 and TLR4, in blood and different brain regions, and depending signaling cascades are paralleling aging associated alterations of cognition in healthy aging mice. Cognitive function was assessed in the Y-maze and intestinal and brain tissue and blood were collected in young (4 months old) and old (24 months old) male C57BL/6 mice to determine intestinal microbiota composition by Illumina amplicon sequencing, the concentration of TLR2 and TLR4 ligands in plasma and brain tissue as well as to determine markers of intestinal barrier function, senescence and TLR2 and TLR4 signaling. Cognitive function was significantly impaired in old mice. Also, in old mice, intestinal microbiota composition was significantly altered, while the relative abundance of Gram-negative or Gram-positive bacteria in the small and large intestines at different ages was not altered. Moreover, intestinal barrier function was impaired in small intestine of old mice, and the levels of TLR2 and TLR4 ligands were also significantly higher in both portal and peripheral blood. Furthermore, levels of TLR2 and TLR4 ligands, and downstream markers of TLR signaling were higher in the hippocampal and prefrontal cortex of old mice compared to young animals. Taken together, our results suggest that even in 'healthy' aging, cognitive function is impaired in mice going along with an increased intestinal translocation of TLR ligands and alterations of TLR signaling in several brain regions.

Gut microbiota regulates acute myeloid leukaemia via alteration of intestinal barrier function mediated by butyrate

The gut microbiota has been linked to many cancers, yet its role in acute myeloid leukaemia (AML) progression remains unclear. Here, we show decreased diversity in the gut microbiota of AML patients or murine models. Gut microbiota dysbiosis induced by antibiotic treatment accelerates murine AML progression while faecal microbiota transplantation reverses this process. Butyrate produced by the gut microbiota (especially Faecalibacterium) significantly decreases in faeces of AML patients, while gavage with butyrate or Faecalibacterium postpones murine AML progression. Furthermore, we find the intestinal barrier is damaged in mice with AML, which accelerates lipopolysaccharide (LPS) leakage into the blood. The increased LPS exacerbates leukaemia progression in vitro and in vivo. Butyrate can repair intestinal barrier damage and inhibit LPS absorption in AML mice. Collectively, we demonstrate that the gut microbiota promotes AML progression in a metabolite-dependent manner and that targeting the gut microbiota might provide a therapeutic option for AML.

Mucosal healing progression after acute colitis in mice.

BACKGROUNDMucosal healing has become a therapeutic goal to achieve stable remission in patients with inflammatory bowel diseases. To achieve this objective, overlapping actions of complex cellular processes, such as migration, proliferation, and differentiation, are required. These events are longitudinally and tightly controlled by numerous factors including a wide range of distinct regulatory proteins. However, the sequence of events associated with colon mucosal repair after colitis and the evolution of the luminal content characteristics during this process have been little studied.AIMTo document the evolution of colon mucosal characteristics during mucosal healing using a mouse model with chemically-induced colitis.METHODSC57BL/6 male mice were given 3.5% dextran sodium sulfate (DSS) in drinking water for 5 d. They were euthanized 2 (day 7), 5 (day 10), 8 (day 13), and 23 (day 28) d after DSS removal. The colonic luminal environment and epithelial repair processes during the inflammatory flare and colitis resolution were analyzed with reference to a non-DSS treated control group, euthanized at day 0. Epithelial repair events were assessed histo-morphologically in combination with functional permeability tests, expression of key inflammatory and repairing factors, and evaluation of colon mucosa-adherent microbiota composition by 16S rRNA sequencing.RESULTSThe maximal intensity of colitis was concomitant with maximal alterations of intestinal barrier function and histological damage associated with goblet cell depletion in colon mucosa. It was recorded 2 d after termination of the DSS-treatment, followed by a progressive return to values similar to those of control mice. Although signs of colitis were severe (inflammatory cell infiltrate, crypt disarray, increased permeability) and associated with colonic luminal alterations (hyperosmolarity, dysbiosis, decrease in short-chain fatty acid content), epithelial healing processes were launched early during the inflammatory flare with increased gene expression of certain key epithelial repair modulators, including transforming growth factor-β, interleukin (Il)-15, Il-22, Il-33, and serum amyloid A. Whereas signs of inflammation progressively diminished, luminal colonic environment alterations and microscopic abnormalities of colon mucosa persisted long after colitis induction.CONCLUSIONThis study shows that colon repair can be initiated in the context of inflamed mucosa associated with alterations of the luminal environment and highlights the longitudinal involvement of key modulators.

Beneficial effects of Saccharomyces boulardii CNCM I-745 on clinical disorders associated with intestinal barrier disruption.

Intestinal barrier defects lead to “leaky gut syndrome”, defined as an increase in intestinal permeability that allows the passage of luminal content into intestinal tissue and the bloodstream. Such a compromised intestinal barrier is the main factor underlying the pathogenesis of inflammatory bowel disease, but also commonly occurs in various systemic diseases such as viral infections and metabolic syndrome. The non-pathogenic yeast Saccharomyces boulardii CNCM I-745 has demonstrated its effectiveness as a probiotic in the prevention and treatment of antibiotic-associated, infectious and functional diarrhea. Via multiple mechanisms of action implicated in intestinal barrier function, S. boulardii has beneficial effects on altered intestinal microbiota and epithelial barrier defects in different pathologies. The well-studied probiotic yeast S. boulardii plays a crucial role in the preservation and/or restoration of intestinal barrier function in multiple disorders. This could be of major interest in diseases characterized by alterations in intestinal barrier function.

Short-Term Intake of a Fructose-, Fat- and Cholesterol-Rich Diet Causes Hepatic Steatosis in Mice: Effect of Antibiotic Treatment.

Intestinal microbiota and barrier functions seem to play an important role in the development of non-alcoholic fatty liver disease (NAFLD). However, whether these changes are an early event in the development of NAFLD or are primarily associated with later stages of the disease, has not yet been clarified. Using a pair-feeding model, we determined the effects of a short-term intake of a fat-, fructose- and cholesterol-rich diet (FFC) on the development of early hepatic steatosis and markers of intestinal barrier function in mice treated with and without non-resorbable antibiotics (AB). For four days, C57BL/6J mice were either pair-fed a control diet or a FFC diet ± AB (92 mg/kg body weight (BW) polymyxin B and 216 mg/kg BW neomycin). Hepatic steatosis and markers of inflammation, lipidperoxidation and intestinal barrier function were assessed. Lipid accumulation and early signs of inflammation found in the livers of FFC-fed mice were markedly attenuated in FFC + AB-fed animals. In FFC-fed mice the development of NAFLD was associated with a significant loss of tight junction proteins and an induction of matrix metalloproteinase-13 in the upper parts of the small intestine as well as significantly higher portal endotoxin levels and an induction of dependent signaling cascades in the liver. As expected, portal endotoxin levels and the expression of dependent signaling cascades in liver tissue were almost at the level of controls in FFC + AB-fed mice. However, FFC + AB-fed mice were also protected from the loss of zonula occludens-1 and partially of occludin protein in small intestine. Our data suggest that the development of early diet-induced hepatic steatosis in mice at least in part results from alterations of intestinal barrier function.

Age and Sex Normalization of Intestinal Permeability Measures for the Improved Assessment of Enteropathy in Infancy and Early Childhood: Results From the MAL-ED Study.

The aim of the study was to describe changes in intestinal permeability in early childhood in diverse epidemiologic settings. In a birth cohort study, the lactulose:mannitol (L:M) test was administered to 1980 children at 4 time points in the first 24 months of life in 8 countries. Data from the Brazil site with an incidence of diarrhea similar to that seen in the United States and no growth faltering was used as an internal study reference to derive age- and sex-specific z scores for mannitol and lactulose recoveries and the L:M ratio. A total of 6602 tests demonstrated mannitol recovery, lactulose recovery, and the L:M ratio were associated with country, sex, and age. There was heterogeneity in the recovery of both probes between sites with mean mannitol recovery ranging for 1.34% to 5.88%, lactulose recovery of 0.19% to 0.58%, and L:M ratios 0.10 to 0.17 in boys of 3 months of age across different sites. We observed strong sex-specific differences in both mannitol and lactulose recovery, with boys having higher recovery of both probes. Alterations in intestinal barrier function increased in most sites from 3 to 9 months of age and plateaued or diminished from 9 to 15 months of age. Alterations in recovery of the probes differ markedly in different epidemiologic contexts in children living in the developing world. The rate of change in the L:M-z ratio was most rapid and consistently disparate from the reference standard in the period between 6 and 9 months of age, suggesting that this is a critical period of physiologic impact of enteropathy in these populations.

Fish oil enhances intestinal barrier function and inhibits corticotropin-releasing hormone/corticotropin-releasing hormone receptor 1 signalling pathway in weaned pigs after lipopolysaccharide challenge.

Stress induces injury in intestinal barrier function in piglets. Long-chain n-3 PUFA have been shown to exhibit potential immunomodulatory and barrier protective effects in animal models and clinical trials. In addition, corticotropin-releasing hormone (CRH)/CRH receptor (CRHR) signalling pathways play an important role in stress-induced alterations of intestinal barrier function. We hypothesised that fish oil could affect intestinal barrier function and CRH/CRHR signalling pathways. In total, thirty-two weaned pigs were allocated to one of four treatments. The experiment consisted of a 2×2 factorial design, and the main factors included immunological challenge (saline or lipopolysaccharide (LPS)) and diet (5 % maize oil or 5 % fish oil). On d 19 of the trial, piglets were treated with saline or LPS. At 4 h after injection, all pigs were killed, and the mesenteric lymph nodes (MLN), liver, spleen and intestinal samples were collected. Fish oil decreased bacterial translocation incidence and the number of translocated micro-organisms in the MLN. Fish oil increased intestinal claudin-1 protein relative concentration and villus height, as well as improved the intestinal morphology. In addition, fish oil supplementation increased intestinal intraepithelial lymphocyte number and prevented elevations in intestinal mast cell and neutrophil numbers induced by LPS challenge. Moreover, fish oil tended to decrease the mRNA expression of intestinal CRHR1, CRH and glucocorticoid receptors. These results suggest that fish oil supplementation improves intestinal barrier function and inhibits CRH/CRHR1 signalling pathway and mast cell tissue density.

Dietary intervention with serum-derived bovine immunoglobulins protects barrier function in a mouse model of colitis.

Dietary supplementation with immunoglobulins from animal plasma has anti-inflammatory effects on intestinal and lung models of acute inflammation. Here, we aimed to establish whether dietary intervention with serum-derived bovine immunoglobulin (SBI) can prevent alterations in intestinal barrier function in a mouse model with a genetic predisposition to inflammatory bowel disease (IBD). Wild-type (WT) mice and mice lacking the mdr1a gene (KO) were fed diets supplemented with either SBI (2% wt/wt) or milk proteins (control diet), from day 21 (weaning) until day 56. The epithelial permeability of distal colon crypts was measured by confocal microscopy using a fluorescent marker. The expression of junctional epithelial E-cadherin and β-catenin proteins were determined by Western blot and zonula occludens-1 (ZO-1) by immunofluorescence. Mucins (MUC1, MUC2, MUC4), TFF3, cytokines (TNF-α, IFN-γ), and inducible nitric oxide synthase RNA expression were quantified by real-time PCR. SBI blocked the increase in colon crypt permeability and partially prevented the reduction in E-cadherin and ZO-1 expression that characterize the KO mouse model (both P < 0.05). SBI inclusion also reduced the mucosal expression of the inflammatory markers TNF-α, IFN-γ, and inducible nitric oxide synthase (all P < 0.005). The number of goblet cells in the colon of KO mice was low and correlated well with MUC2 and TFF3 expression (P < 0.001), whereas dietary supplementation with SBI attenuated these effects (all P < 0.05). In short, dietary SBI ameliorated colonic barrier alterations and reduced the expression of mucosal inflammatory markers in a genetic model of IBD.

Dietary squid ink polysaccharide induces goblet cells to protect small intestine from chemotherapy induced injury.

Gastrointestinal mucositis induced by chemotherapy is associated with alterations of intestinal barrier function due to the potential damage induced by anti-cancer drugs on the epithelial cells. Goblet cells, an important epithelial lining in the intestine, contribute to innate immunity by secreting mucin glycoproteins. Employing a mouse model of chemotherapy induced intestinal mucosal immunity injury by cyclophosphamide, we demonstrated for the first time that polysaccharide from the ink of Ommastrephes bartramii (OBP) enhanced Cyto18, which is a mucin expression in goblet cells. The up-regulation of mucins by OBP relied on the augmented quantity of goblet cells, but not on the changes in the ultrastructure of endoplasmic reticulum (ER). Our results may have important implications for enhanced immunopotentiation function of functional OBP on intestinal mucosal immunity against intestinal disorders involving inflammation and infection.

Alteration of intestinal barrier function during activity-based anorexia in mice

Anorexia nervosa is a severe eating disorder often leading to malnutrition and cachexia, but its pathophysiology is still poorly defined. Chronic food restriction during anorexia nervosa may induce gut barrier dysfunction, which may contribute to disease development and its complications. Here we have characterized intestinal barrier function in mice with activity-based anorexia (ABA), an animal model of anorexia nervosa. Male C57Bl/6 ABA or limited food access (LFA) mice were placed respectively in cages with or without activity wheel. After 5 days of acclimatization, both ABA and LFA mice had progressively limited access to food from 6h/d at day 6 to 3h/d at day 9 and until the end of experiment at day 17. A group of pair-fed mice (PF) was also compared to ABA. On day 17, food intake was lower in ABA than LFA mice (2.0±0.18g vs. 3.0±0.14g, p<0.001) and weight loss was more pronounced in ABA and PF compared to LFA mice (23.6±1.6% and 24.7±0.7% vs. 16.5±1.2%; p<0.05). Colonic histology showed decreased thickness of the muscularis layer in ABA compared to LFA mice (p<0.05). Colonic permeability was increased in both ABA and PF compared to LFA mice (p<0.05) but jejunal paracellular permeability was not affected. Expression of claudin-1 in the colon was lower in the ABA than the LFA group (p<0.05), whereas occludin expression remained unaffected. Increased colonic permeability and histological alterations found in ABA mice suggest that intestinal barrier dysfunction may also occur in anorexia nervosa. The role of these alterations in the pathophysiology of anorexia nervosa should be further evaluated.

The Role of Lactic Acid Bacteria in the Pathophysiology and Treatment of Irritable Bowel Syndrome (IBS)

Irritable bowel syndrome (IBS) is a multifactorial chronic disorder characterized by various abdominal complaints and a worldwide prevalence of 10% - 20%. Although its etiology and pathophysiology are complex and still not completely understood, aberrations along the microbe-gut-brain axis are known to play a central role. IBS is characterized by interrelated alterations in intestinal barrier function, gut microbe composition, immune activation, afferent sensory signaling and brain activity. Pharmaceutical treatment is generally ineffective and, hence, most therapeutic strategies are based on non-drug approaches. A promising option is the administration of probiotics, in which lactic acid bacteria strains are considered specifically beneficial. This review aims to provide a concise, although comprehensive, overview of the role of lactic acid bacteria in the pathophysiology and treatment of IBS.

Ultrastructural mucosal alterations and increased intestinal permeability in non-celiac, type I diabetic patients

Background. Increased intestinal permeability was described in several intestinal auto-immune conditions. There are very few and contradictory reports about type I diabetes mellitus, an auto-immune condition sometimes associated with celiac disease. Aims. To investigate intestinal permeability in type I diabetes mellitus patients with no concomitant celiac disease, with a comparison to ultra-structural aspects of duodenal mucosa. Patients. 46 insulin dependent diabetes mellitus, non-celiac, patients (18 females and 28 males, mean age 15.8±5.3 [S.D.] years) were enrolled. The mean duration of the disease was 5.7 years. Methods. The morphological aspect of the small bowel mucosa, at standard light microscopy and electron transmission microscopy, along with intestinal permeability (by lactulose/mannitol test) were studied. Lactulose and mannitol urinary excretion were determined by means of high performance anion exchange chromatography–pulsed amperometric detection. Results. The lactulose/mannitol ratio was 0.038 [0.005−0.176] (median and range) in 46 patients compared to 0.014 [0.004−0.027] in 23 controls: insulin dependent diabetes mellitus group values being significantly higher than those of the controls ( P<0.0001, Mann–Whitney test). Eight insulin dependent diabetes mellitus patients underwent endoscopy and biopsies were analysed by means of light microscopy and transmission electron microscopy. At the light microscopy level, none of the biopsy samples showed any sign of atrophy nor inflammation, whereas transmission electron microscopy analysis showed remarkable ultra-structural changes in six out of the eight patients. Four parameters were evaluated: height and thickness of microvilli, space between microvilli and thickness of tight junctions. Conclusions. This alteration of intestinal barrier function in non-celiac type I diabetes mellitus, frequently associated with mucosal ultra-structural alterations, could suggest that a loss of intestinal barrier function can be a pathogenetic factor in a subset of insulin dependent diabetes mellitus patients.

Polyunsaturated fatty acids reduce non‐receptor‐mediated transcellular permeation of protein across a model of intestinal epithelium in vitro

Dietary polyunsaturated fatty acids influence the natural history of intestinal inflammatory diseases. Varying the types of long-chain fatty acids that are exposed to cells alters the physicochemical properties of cell membranes. This study aimed to determine whether such variations alter transcellular and paracellular permeability in intestinal epithelium. Monolayers of Caco-2 cells, allowed to differentiate by culturing for 7 days following confluence, were used as the model for intestinal epithelium. Paracellular permeability was assessed by measurement of transepithelial resistance, while transcellular permeability was assessed by the transepithelial flux of horseradish peroxidase. Exposure of the cells to 100 micromol/L of palmitic acid, oleic acid, eicosapentaenoic acid, or linoleic acid, was not toxic to cells (measured by leakage of lactate dehydrogenase), and altered cell membrane fatty acid composition (as measured by gas chromatography). Flux of horseradish peroxidase was significantly affected by 24 h fatty acid exposure (P= 0.038, ANOVA), being decreased by 23 +/- 6% (mean +/- SEM) by eicosapentaenoic acid and 25 +/- 3% by linoleic acid. Oleic acid, palmitic acid and butyrate, had no effect. Transepithelial resistance also varied significantly across the treatment groups (P< 0.001) due to a 28 +/- 5% increase induced by butyrate. The long-chain fatty acids had no effect. Both omega-3 and omega-6 polyunsaturated fatty acids reduce transcellular, non-receptor-mediated permeation of proteins across differentiated Caco2 cell monolayers, without altering paracellular permeability. Alteration of intestinal barrier function should be considered as a possible mechanism of action of dietary polyunsaturated fatty acids.

Alterations in intestinal barrier function do not predispose to translocation of enteric bacteria in gastroenterologic patients.

Bacterial translocation from the intestinal lumen has been demonstrated in humans. Three mechanisms have been suggested to explain the phenomenon: altered intestinal barrier function, bacterial overgrowth, and impaired host defense. The aim of this study was to determine whether changes in intestinal barrier function assessed by measurement of intestinal permeability and morphology were associated with alteration in bacterial translocation. Intestinal permeability was assessed in 43 patients by the lactulose/L-rhamnose test with a 5-h urine collection. Mucosal atrophy was assessed from the villus height-to-mucosal thickness ratio in small-bowel biopsies. Bacterial translocation was determined by microbiologic analysis of harvested mesenteric lymph nodes. No significant differences were apparent in the incidence of bacterial translocation in patients with normal permeability (5 [23%] of 22 patients translocated) compared with patients with increased permeability (4 [19%] of 21 patients translocated). Similarly, no correlation was apparent between the incidence of bacterial translocation and the index of villus atrophy. The degree of villus atrophy failed to correlate with gastrointestinal permeability. These data suggest that the incidence of bacterial translocation is not related to increased intestinal permeability or mucosal atrophy.