Duodenal Mucosal Barrier in Functional Dyspepsia [mRNA]
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ABSTRACT: Epithelial Barrier and Leaky Gut in Dyspepsia Running title: Epithelial Barrier and Leaky Gut in Dyspepsia Context: Some studies suggest that FD is associated with ex vivo duodenal epithelial micro-inflammation and barrier impairment; the pathogenesis of these findings is unclear. miRNAs reduce expression of epithelial barrier genes and have been postulated to increase epithelial permeability in irritable bowel syndrome. New findings: Compared to controls, there is reduced mRNA expression of several barrier proteins (zona occludin-1), increased expression of several miRNAs (eg, miR-142-3p) that suppress the genes for barrier proteins in FD. However, mucosal eosinophils, intraepithelial lymphocytes, and mast cells, ex- and in vivo permeability (urinary lactulose and mannitol excretion) were not significantly different in FD. Impact: Patients with FD do not have a leaky gut syndrome.
Project description:Epithelial Barrier and Leaky Gut in Dyspepsia Running title: Epithelial Barrier and Leaky Gut in Dyspepsia Context: Some studies suggest that FD is associated with ex vivo duodenal epithelial micro-inflammation and barrier impairment; the pathogenesis of these findings is unclear. miRNAs reduce expression of epithelial barrier genes and have been postulated to increase epithelial permeability in irritable bowel syndrome. New findings: Compared to controls, there is reduced mRNA expression of several barrier proteins (zona occludin-1), increased expression of several miRNAs (eg, miR-142-3p) that suppress the genes for barrier proteins in FD. However, mucosal eosinophils, intraepithelial lymphocytes, and mast cells, ex- and in vivo permeability (urinary lactulose and mannitol excretion) were not significantly different in FD. Impact: Patients with FD do not have a leaky gut syndrome.
Project description:Clostridioides difficile (C. difficile) toxins A (TcdA) and B (TcdB) cause antibiotic-associated colitis, increasing morbidity and mortality. Accurate in vitro models are necessary to detect early toxicity kinetics, investigate disease etiology, and develop preclinical models for new therapies. Properties of cancer cell lines and organoids inherently limit these efforts. We developed adult stem cell-derived monolayers of differentiated human colonic epithelium (hCE) with barrier function, investigated the impact of toxin application to apical/basal aspects of monolayers, and evaluated whether a leaky epithelial barrier enhances toxicity. Single-cell RNA-sequencing (scRNAseq) mapped C. difficile-relevant genes to human gut epithelial lineages. Transcriptomics informed timing of stem cell differentiation to achieve in vitro colonocyte maturation like that observed in vivo. Transepithelial electrical resistance (TEER) and fluorescent dextran permeability assays measured cytotoxicity as barrier loss post-toxin exposure. Leaky epithelial barriers were induced with diclofenac. scRNAseq demonstrated broad and variable toxin receptor expression across human gut lineages. Absorptive colonocytes displayed generally enhanced toxin receptor, Rho GTPase, and cell junction expression. 22-day differentiated Caco-2 cells remained immature whereas hCE monolayers were similar to mature colonocytes. hCE monolayers exhibited high barrier function after 1-day differentiation. Basal TcdA/B application to monolayers caused greater toxicity and apoptosis. Diclofenac induced leaky hCE monolayers and enhanced toxicity of apical TcdB exposure. Apical/basal toxicities are uncoupled with more rapid onset and increased magnitude of basal toxicity. Leaky paracellular junctions enhance toxicity of apical TcdB exposure. hCE monolayers represent a physiologically relevant and sensitive culture system to evaluate the impact of microbial toxins on gut epithelium.
Project description:Breastfeeding has been associated with long lasting health benefits. Nutrients and bioactive components of human breast milk promote cell growth, immune development, and shield the infant gut from insults and microbial threats. The molecular and cellular events involved in these processes are ill defined. We have established human pediatric enteroids and interrogated maternal milk’s impact on epithelial cell maturation and function in comparison with commercial infant formula. Colostrum applied apically to pediatric enteroid monolayers reduced ion permeability, stimulated epithelial cell differentiation, and enhanced tight junction function by upregulating occludin amount. Breast milk heightened the production of antimicrobial peptide -defensin 5 by goblet and Paneth cells, and modulated cytokine production, which abolished apical release of pro-inflammatory GM-CSF. These attributes were not found in commercial infant formula. Epithelial cells exposed to breast milk elevated apical and intracellular pIgR amount and enabled maternal IgA translocation. Proteomic data revealed a breast milk-induced molecular pattern associated with tissue remodeling and homeostasis. Using a novel ex vivo pediatric enteroid model, we have identified cellular and molecular pathways involved in human milk-mediated improvement of human intestinal physiology and immunity.
Project description:The ERC “MINERVA” project (GA 724734) aims at developing a multi-organ-on-a-chip engineered platform to recapitulate in vitro the main players involved in the MGBA crosstalk: the microbiota, the gut epithelium, the immune system, the blood-brain barrier and the brain. In this context, the gut epithelium represents a physiological barrier that separates the intestinal lumen from the systemic circulation, and in several pathological circumstances, seems that its permeability might significantly increase and allow the passage of biologically active molecules into the blood vessels surrounding the intestinal mucosa. In the present work, we present our MINERVA 2.0 device and our innovative gut-on-a-chip device obtained by culturing in MINERVA 2.0 and a human gut epithelial CaCo2 cell based model. In particular, we have cultured the cells under perfusion and have assessed cell behavior by addressing cellular viability, tight junction imaging, apparent permeability by FITC-Dextran and transepithelial electrical resistance evaluation. Transcriptomic profile was used to further elucidate the effects of dynamic perfusion on Caco-2 cells.
Project description:Claudin proteins are major constituents of epithelial and endothelial tight junctions (TJ), where they serve as regulators of paracellular permeability to ions and solutes. Claudin-18, a member of the large claudin family, is highly expressed in lung epithelium. To elucidate the role of claudin-18 in alveolar epithelial barrier function and fluid homeostasis, we generated claudin-18 knockout (C18 KO) mice. Increased alveolar fluid clearance (AFC) observed in C18 KO mice may have accounted for absence of lung edema despite increased alveolar solute permeability compared to wild type (WT) controls. Higher AFC in C18 KO mice was associated with higher Na-K-ATPase activity and increased expression of the Na-K-ATPase β1 subunit compared to WT controls. Consistent with in vivo findings, alveolar epithelial cell (AEC) monolayers derived from C18 KO mice exhibited lower transepithelial electrical resistance (RT) accompanied by increased solute and ion permeability without changes in ion selectivity. Expression of claudin-3 and claudin-4 was markedly increased in whole lung and in freshly isolated AEC from C18 KO mice, while claudin-5 was unchanged. In contrast, occludin, another major component of the TJ complex, was significantly decreased in C18 KO lung. Further analysis revealed rearrangements in the F-actin cytoskeleton in C18 KO MAECM. These findings demonstrate a crucial non-redundant role for claudin-18 in regulation of alveolar epithelial tight junction composition and permeability to ions and solutes. Importantly, increased AFC in C18 KO mice identifies additional roles for claudin-18 in alveolar fluid homeostasis beyond its direct contributions to barrier properties of the alveolar epithelium. Animals with a ubiquitous knockout (C18 KO) were obtained by crossing mice harboring a conditional (floxed) allele of claudin-18 (Cldn18F/F) with CMV-cre deleter mice to delete exons 2 and 3 by Cre/loxP recombination.
Project description:Background/ Aim: Diabetes has substantive co-occurrence with disorders of gut-brain interactions (DGBIs). The pathophysiological and molecular mechanisms linking diabetes and DGBIs are unclear. miRNAs are key regulators of diabetes and gut dysmotility. We investigated whether impaired gut barrier function regulated by a key miRNA, miR-10b-5p, links diabetes and gut dysmotility. Methods: We created a new mouse line using the Mb3Cas12a/Mb3Cpf1 endonuclease to knock out mir-10b globally. Loss of function studies were conducted to characterize diabetes, gut dysmotility, and gut barrier dysfunction phenotypes in these mice. Gain of function studies were conducted by injecting these mice with a miR-10b-5p mimic. Further, we performed miRNA-sequencing analysis from colonic mucosa from mir-10b KO, WT, and miR-10b-5p mimic injected mice to confirm 1) deficiency of miR-10b-5p in KO mice, and 2) restoration of miR-10b-5p expression after the mimic injection. Results: Congenital loss of mir-10b in mice led to the development of hyperglycemia, gut dysmotility, and gut barrier dysfunction. We found increased gut permeability and reduced expression of the tight junction protein Zonula occludens-1 (ZO-1), in the colon of mir-10b KO mice. We further confirmed that patients with diabetes or IBS-C, a known DGBI that is linked to leaky gut, had significantly reduced miR-10b-5p expression. Injection of a miR-10b-5p mimic in mir-10b KO mice rescued these molecular alterations and phenotypes. Conclusion: Our study uncovered a potential pathophysiologic mechanism of gut barrier dysfunction that links both the diabetes and gut dysmotility phenotypes in mice lacking miR-10b-5p. Treatment with a miR-10b-5p mimic reversed the leaky gut, diabetic, and gut dysmotility phenotypes, highlighting the translational potential of miR-10b-5p mimic.
Project description:The study describes miRNA expression in intact jejunum following feeding of gluten containing monkey chow to gluten sensitive (GS) rhesus macaques. Gluten feeding induced several inflammation associated miRNAs validated and predicted to directly target intestinal tight junction proteins. Upregulation of these microRNAs was accompanied significantly reduced mRNA expression of claudin-1, claudin-3 and occludin and severe gut dysbiosis. These findings suggest that miRNA mediated downregulation of intestinal epithelial tight junction proteins could increase intestinal permeability and facilitate translocation of dysbiotic bacteria into the systemic circulation.
Project description:The role of environmental factors and gender disparities as determinants of health is incontrovertible. In the digestive sphere, it is noteworthy that one of the most prevalent diseases such as irritable bowel syndrome (IBS) has a predominance in females. The origin of IBS is related to mucosal microinflammation phenomena, psychosocial stress, and in the last years, alterations in gut microbiota. Recent observations from our group in healthy subjects, demonstrate that both chronic psychosocial stress, and female gender per se determine a significant intestinal epithelial barrier dysfunction in response to intercurrent stimuli, which, in susceptible individuals, could result in an early stage in the development of more lasting changes and the onset of clinical manifestations of IBS. Although the intimate mechanisms involved in stress-induced intestinal pathophysiology are not well known, diverse studies suggest that gut microbiota alteration, through epigenetic modifications of the main stress-mediators could be one of them. However, solid scientific evidence demonstrating the influence of stress on gut microbiota and epigenetics of the main stress-mediators is missing. Therefore, we want to investigate and characterize gender-dependent epigenetic modifications involved in intestinal barrier dysfunction in response to acute stress. The identification of gender-dependent abnormal epigenetic patterns related to female gender dysfunction can make a breakthrough in the understanding of the pathophysiology of the regulation of intestinal permeability, and promote positive diagnostic and therapeutic future progress in IBS.
Project description:Probiotics have been suggested to ameliorate the function of the intestinal epithelial barrier and so have several mediators and receptors of the expanded endocannabinoid system, the endocannabinoidome (eCBome). Here we cocultured three live strains of Lactiplantibacillus plantarum with intestinal epithelial organoids to study their effects on the gut barrier function and the possible involvement of the eCBome in this effect. All three L.plantarum strains variously reduced the trans-epithelial permeability of intestinal organoids and promoted increased mRNA expression of several tight junction proteins and intestinal barrier proteins. Concomitantly, the three strains upregulated the expression of genes encoding biosynthetic enzymes (i.e., NapePLD, Abdh4, Gde1, Daglb) and receptors (i.e., Cnr1, Cnr2, Gpr55, and Ppara), while concurrently downregulating the expression of two essential catabolic enzymes (i.e. Faah and Naaa), involved in the signaling of several eCBome mediators known for their role in regulating the intestinal epithelial barrier. Selective inhibitors of eCBome mediator degrading enzymes FAAH and MAGL, i.e., URB597 and JZL184, increased N-acyl-ethanolamine (NAE) and 2-monoacylglycerol (2-MAG) levels, respectively, enhanced the expression of intestinal epithelial barrier genes and reduced the trans-epithelial permeability of organoids, as for L. plantarum strains. Interestingly, inflammation-induced trans-epithelial permeability in organoids was also reversed by both FAAH and MAGL inhibitors. We surmise that elevated endogenous levels of either NAEs or 2-MAGs promote improvement in small intestine trans-epithelial permeability and that L. plantarum strains may exploit this mechanism to promote these beneficial effects.
Project description:Despite the rising popularity of e-cigarette and vaping devices, their safety continues to be questioned. Using established murine models of acute and chronic e-cigarette aerosol inhalation, murine colon transcriptomics and organoid co-culture models, here we assessed the effects of e-cigarette use on the gut barrier. Histologic and transcriptome analyses revealed that chronic, but not acute, nicotine-free e-cigarette use was associated with inflammation and reduced expression of tight junction markers, including occludin. Exposure of murine and human enteroid-derived monolayers (EDMs) to nicotine-free e-cigarette aerosols alone or in co-culture with invasive E. coli, recapitulated the key findings observed in vivo, i.e., barrier-disruption, downregulation of occludin, inflammation, and an accentuated risk of and response to bacterial infection. These data highlight an unexpected harmful effect of ecigarette use on the gut barrier and pinpoint non-nicotine chemical components as the source of harm. Considering the importance of an intact gut barrier for host fitness, and the impact of gut mucosal inflammation on a multitude of chronic diseases, these findings are broadly relevant to medicine and public health.