Gut Barrier Dysfunction Research Articles

Puerariae lobatae Radix ameliorates chronic kidney disease by reshaping gut microbiota and downregulating Wnt/β‑catenin signaling.

Gut microbiota dysfunction is a key factor affecting chronic kidney disease (CKD) susceptibility. Puerariae lobatae Radix (PLR), a traditional Chinese medicine and food homologous herb, is known to promote the gut microbiota homeostasis; however, its role in renoprotection remains unknown. The present study aimed to investigate the efficacy and potential mechanism of PLR to alleviate CKD. An 8‑week 2% NaCl‑feeding murine model was applied to induce CKD and evaluate the therapeutic effect of PLR supplementary. After gavage for 8 weeks, The medium and high doses of PLR significantly alleviated CKD‑associated creatinine, urine protein increasement and nephritic histopathological injury. Moreover, PLR protected kidney from fibrosis by reducing inflammatory response and downregulating the canonical Wnt/β‑catenin pathway. Furthermore, PLR rescued the gut microbiota dysbiosis and protected against high salt‑induced gut barrier dysfunction. Enrichment of Akkermansia and Bifidobacterium was found after PLR intervention, the relative abundances of which were in positive correlation with normal maintenance of renal histology and function. Next, fecal microbiota transplantation experiment verified that the positive effect of PLR on CKD was, at least partially, exerted through gut microbiota reestablishment and downregulation of the Wnt/β‑catenin pathway. The present study provided evidence for a new function of PLR on kidney protection and put forward a potential therapeutic strategy target for CKD.

Chlorogenic Acid/Linoleic Acid-Fortified Wheat-Resistant Starch Ameliorates High-Fat Diet-Induced Gut Barrier Damage by Modulating Gut Metabolism.

This study aimed to investigate alterations in gut microbiota and metabolites mediated by wheat-resistant starch and its repair of gut barrier dysfunction induced by a high-fat diet (HFD). Structural data revealed that chlorogenic acid (CA)/linoleic acid (LA) functioned through noncovalent interactions to form a more ordered structure and fortify antidigestibility in wheat starch (WS)-CA/LA complexes; the resistant starch (RS) contents of WS-CA, WS-LA, and WS-CA-LA complexes were 23.40 ± 1.56%, 21.25 ± 1.87%, and 35.47 ± 2.16%, respectively. Dietary intervention with WS-CA/LA complexes effectively suppressed detrimental alterations in colon tissue morphology induced by HFD and repaired the gut barrier in ZO-1 and MUC-2 levels. WS-CA/LA complexes could augment gut barrier-promoting microbes including Parabacteroides, Bacteroides, and Muribaculum, accompanied by an increase in short-chain fatty acids (SCFAs) and elevated expression of SCFA receptors. Moreover, WS-CA/LA complexes modulated secondary bile acid metabolism by decreasing taurochenodeoxycholic, cholic, and deoxycholic acids, leading to the activation of bile acid receptors. Collectively, this study offered guiding significance in the manufacture of functional diets for a weak gut barrier.

Paneth cell-specific TCF4 down-regulation potentiates alcohol-induced dysbiosis of gut microbiota and tissue injury at the gut-liver axis

Introduction: Alcohol misuse results in hepatitis, pancreatitis, and neurodegenerative disorders. Alcohol consumption alters gut microbiota and increases gut permeability, leading to endotoxemia and multiple organ damage. However, the cellular and molecular mechanisms of alcohol-induced microbiota dysbiosis and barrier dysfunction remain poorly defined. Antimicrobial peptides such as α-defensins, secreted by the Paneth cells, regulate gut microbiota homeostasis. We previously reported that ethanol (EtOH) feeding reduces α-defensin expression in mice. α-Defensin expression is regulated by Wnt signaling and T-cell factor 4 (TCF4). We investigated the role of Paneth cell TCF4 in alcohol-induced microbiota dysbiosis and tissue injury at the gut-liver axis. Materials and methods: TCF4fl/wt (WT) and TCF4fl/wt-Defa6Cre (KD; heterozygous Paneth cell-specific knockout of TCF4) mice were fed a Lieber-DiCarli liquid diet with or without EtOH (0% 2d, 1% 2d, 2% 2d, 4% 1wk, 5% 1wk, & 6% 1wk) (EF). Control groups were pair-fed (PF) isocaloric EtOH-free diet. Intestinal permeability was measured by the vascular-to-luminal flux of FITC-inulin (6 kDa) in vivo, and tight junction (TJ) and adherens junction (AJ) integrity were assessed by confocal microscopy for occludin, ZO-1, E-cadherin, and β-catenin. Paneth cell function and mucosal inflammation were assessed by RT-PCR for defensins and cytokines. Gut microbiota was analyzed by 16S rRNA sequencing of colonic flushing. Plasma lipopolysaccharide (LPS) and cytokines were measured to evaluate endotoxemia and systemic inflammation. Liver damage was assessed by measuring plasma AST, liver triglyceride, and cytokine mRNA. Results and conclusion: EtOH reduced TCF4 expression in the ileum in both WT and KD mice; lowest TCF4 expression was observed in KD-EF mice. Similarly, the expression of DEFA5 and DEFA6 was reduced by EtOH in WT and KD mice, with the lowest expression in KD-EF mice. EtOH-induced mucosal permeability was associated with reduced staining for TJ and AJ proteins, indicating the mucosal barrier dysfunction. EtOH increased intestinal mRNA for IL-1β, IL-6, TNFα, and MCP-1, indicating the mucosal inflammatory response. EtOH-induced gut permeability, TJ/AJ disruption, and mucosal inflammation were significantly higher in KD-EF mice than in WT-EF mice. Shannon index analysis indicated that EtOH reduced α-diversity of microbiota in KD but not in WT mice. Firmicutes: Bacteriodetes ratio and the abundance of Verrucomicrobia were reduced by EtOH in WT but not in KD mice. The abundance of Bacillus was increased by EtOH both in WT and KD mice; however, this effect was more severe in KD mice. EtOH-induced plasma LPS and cytokine elevations were higher in KD mice than in WT mice. Elevation of plasma AST, liver triglyceride, and liver cytokine mRNA indicated EtOH-induced liver damage; the damage was more severe in KD mice. These data indicate that Paneth cell TCF4 downregulation exacerbates alcohol-induced microbiota dysbiosis, gut barrier dysfunction, endotoxemia, systemic inflammation, and liver damage; suggesting that Paneth cell Wnt signal downregulation plays a crucial role in alcohol-associated organ damage. NIH/NIAA - R01AA012307, AA029270; Veterans Administration - IO1BX003014. 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.

Obesity and polycystic ovary syndrome influence on intestinal permeability at fasting, and modify the effect of diverse macronutrients on the gut barrier

Women with the extremely prevalent polycystic ovary syndromegather multiple cardiovascular risk factors and chronic subclinical inflammation. Interactions between diet, adiposity, and gut microbiota modulate intestinal permeabilityand bacterial product translocation, and may contribute to the chronic inflammation process associated with the polycystic ovary syndrome. In the present study, we aimed to address the effects of obesity, functional hyperandrogenism, and diverse oral macronutrients on intestinal permeabilityby measuring circulating markers of gut barrier dysfunction and endotoxemia. Participants included 17 non-hyperandrogenic control women, 17 women with polycystic ovary syndrome, and 19 men that were submitted to glucose, lipid, and protein oral loads. Lipopolysaccharide-binding protein, plasma soluble CD14, succinate, zonulin family peptide, and glucagon-like peptide-2 were determined at fasting and after oral challenges. Macronutrient challenges induced diverse changes on circulating intestinal permeabilitybiomarkers in the acute postprancial period, with lipids and proteins showing the most unfavorable and favorable effects, respectively. Particularly, lipopolysaccharide-binding protein, zonulin family peptide, and glucagon-like peptide-2 responses were deregulated by the presence of obesity after glucose and lipid challenges. Obese subjects showed higher fasting intestinal permeabilitybiomarkers levels than non-obese individuals, except for plasma soluble CD14. The polycystic ovary syndromeexacerbated the effect of obesity further increasing fasting glucagon-like peptide-2, lipopolysaccharide-binding protein, and succinate concentrations. We observed specific interactions of the polycystic ovary syndromewith obesity in the postprandial response of succinate, zonulin family peptide, and glucagon-like peptide-2. In summary, obesity and polycystic ovary syndromemodify the effect of diverse macronutrients on the gut barrier, and alsoinfluence intestinal permeabilityat fasting,contributing to the morbidity of functional hyperandrogenism by inducing endotoxemia and subclinical chronic inflammation.

Zhilining Formula alleviates DSS-induced colitis through suppressing inflammation and gut barrier dysfunction via the AHR/NF-κBp65 axis

BackgroundRepairing the intestinal mucosal barrier and reducing persistent inflammation is the key strategies for the treatment of ulcerative colitis (UC). Zhilining Formula (ZLN), composed of Andrographis herba (AH), Sophorae flavescentis radix (SFA), and Aucklandia radix (AR), is a well-tried formula for the clinical treatment of enteritis and dysentery in China, and its mechanism has not been clarified. PurposeThis study aims to investigate the effect of ZLN on UC and elucidate its underlying mechanism via metabolomics analysis and experimental verification. MethodsThe effect of ZLN on UC was evaluated in a 3.5 % dextran sulfate sodium (DSS)-induced mice model via the body weight, disease activity index (DAI), colon length, colonic histopathology, expression of inflammation factors, and intestinal barrier in mice. An UPLC-Q-TOF-MS/MS approach-based metabolomics analysis was performed to preliminary explore the mechanism of ZLN in colitis. Based on the results of metabolomics analysis, the expression of related protein or mRNA in AHR/NF-κBp65 axis was determined by qPCR and western blotting. Moreover, the potential interactions of active ingredients of ZLN with NF-κBp65 and AHR were investigated in vitro through using agonists and inhibitors of NF-κBp65 and AHR, respectively. ResultsZLN alleviated body weight loss and colonic shortening in colitis mice, and down-regulated the DAI and histopathological score as well. ZLN also decreased the levels of inflammatory factors (MPO, IL-1β, TNF-α and IL-18), protected goblet cell function and intestinal barrier in DSS-induced mice. Metabolomics results revealed that 36 metabolites that were significantly altered in mice after induction with DSS, which involved in 16 metabolic pathways, including biosynthesis of unsaturated fatty acid, phenylalanine metabolism, arachidonic acid (AA) metabolism, tryptophan (Trp) metabolism, retinol metabolism, and sphingolipid metabolism, etc. ZLN restored 26 different metabolites (DEMs) of them to normal-like levels, indicating ZLN regulated the AA metabolism and Trp-metabolism in UC mice, which hinted its potential pharmacological mechanism related to AHR/NF-κBp65 axis. We further confirmed that ZLN could restrain the activation of NF-κBp65 signaling pathway and then inhibit the expression of its mediated inflammatory cytokines, such as IL-1β, TNF-α, COX-2 and IL17A. Moreover, ZLN increased nuclear translocation of AHR and IL22 expression, which is an important regulatory signal for intestinal mucosal barrier repaired. Finally, we elucidated in vitro that the active ingredients of ZLN exerted anti-colitis effects by activating AHR and simultaneously inhibiting NF-κBp65. ConclusionZLN relieved colitis by AHR/NF-κBp65 axis. This study highlighted the important role of AHR and NF-κBp65 in UC, and provided a theoretical basis for the application of ZLN.

Gut barrier dysfunction and the risk of ICU-acquired bacteremia- a case–control study

BackgroundImpaired intestinal barrier function can enable passage of enteric microorganisms into the bloodstream and lead to nosocomial bloodstream infections during critical illness. We aimed to determine the relative importance of gut translocation as a source for ICU-acquired enterococcal bacteremia of unknown origin.MethodsWe conducted a nested case–control study in two mixed medical-surgical tertiary ICUs in the Netherlands among patients enrolled between 2011 and 2018. We selected 72 cases with ICU-acquired bacteremia due to enterococci (which are known gastrointestinal tract commensals) and 137 matched controls with bacteremia due to coagulase-negative staphylococci (CoNS) (which are of non-intestinal origin). We measured intestinal fatty acid-binding protein, trefoil factor-3, and citrulline 48 h before bacteremia onset. A composite measure for Gut Barrier Injury (GBI) was calculated as the sum of standardized z-scores for each biomarker plus a clinical gastrointestinal failure score.ResultsNo single biomarker yielded statistically significant differences between cases and controls. Median composite GBI was higher in cases than in controls (0.58, IQR − 0.36–1.69 vs. 0.32, IQR − 0.53–1.57, p = 0.33) and higher composite measures of GBI correlated with higher disease severity and ICU mortality (p < 0.001). In multivariable analysis, higher composite GBI was not significantly associated with increased occurrence of enterococcal bacteremia relative to CoNS bacteremia (adjusted OR 1.12 95% CI 0.93–1.34, p = 0.22).ConclusionsWe could not demonstrate an association between biomarkers of gastrointestinal barrier dysfunction and an increased occurrence of bacteremia due to gut compared to skin flora during critical illness, suggesting against bacterial translocation as a major vector for acquisition of nosocomial bloodstream infections in the ICU.

Human-derived bacterial strains mitigate colitis via modulating gut microbiota and repairing intestinal barrier function in mice

BackgroundUnbalanced gut microbiota is considered as a pivotal etiological factor in colitis. Nevertheless, the precise influence of the endogenous gut microbiota composition on the therapeutic efficacy of probiotics in colitis remains largely unexplored.ResultsIn this study, we isolated bacteria from fecal samples of a healthy donor and a patient with ulcerative colitis in remission. Subsequently, we identified three bacterial strains that exhibited a notable ability to ameliorate dextran sulfate sodium (DSS)-induced colitis, as evidenced by increased colon length, reduced disease activity index, and improved histological score. Further analysis revealed that each of Pediococcus acidilactici CGMCC NO.17,943, Enterococcus faecium CGMCC NO.17,944 and Escherichia coli CGMCC NO.17,945 significantly attenuated inflammatory responses and restored gut barrier dysfunction in mice. Mechanistically, bacterial 16S rRNA gene sequencing indicated that these three strains partially restored the overall structure of the gut microbiota disrupted by DSS. Specially, they promoted the growth of Faecalibaculum and Lactobacillus murinus, which were positively correlated with gut barrier function, while suppressing Odoribacter, Rikenella, Oscillibacter and Parasutterella, which were related to inflammation. Additionally, these strains modulated the composition of short chain fatty acids (SCFAs) in the cecal content, leading to an increase in acetate and a decrease in butyrate. Furthermore, the expression of metabolites related receptors, such as receptor G Protein-coupled receptor (GPR) 43, were also affected. Notably, the depletion of endogenous gut microbiota using broad-spectrum antibiotics completely abrogated these protective effects.ConclusionsOur findings suggest that selected human-derived bacterial strains alleviate experimental colitis and intestinal barrier dysfunction through mediating resident gut microbiota and their metabolites in mice. This study provides valuable insights into the potential therapeutic application of probiotics in the treatment of colitis.

Abstract 1478: Chronic perfluorooctanesulfonic acid exposure promotes proliferation of colorectal cancer cells

Abstract Background: Chronic exposure to long-term exposures to per- and polyfluoroalkyl substances (PFAS), widely known as “forever chemicals”, has been associated with multiple negative health outcomes including increased risk of cancer. Perfluorooctanesulfonic acid (PFOS), a “long-chain” subtype of PFAS, has high bioaccumulation potential with a long elimination half-life. PFOS is frequently detected in drinking water leading to its high absorption through the gastrointestinal tract. Recent studies demonstrate that PFAS exposures promote intestinal inflammation and gut barrier dysfunction. However, how a long-term PFOS exposure affects colorectal cancer (CRC) progression is not known. Therefore, the purpose of this study is to delineate the effect of PFOS exposure on CRC cell proliferation and test the potential mitigation strategy for the harmful effects of PFOS. Methods: SW480 and HCT116 cells have been treated with 1 ug/mL PFOS and proliferation was measured at 1, 2, and 3 months using the Presto Blue Cell Viability Reagent fluorescence assay. Proliferation markers were assessed by qPCR and Western blot. Control and PFOS exposed cells were treated with sulforaphane, a nuclear factor erythroid 2-related factor 2 (Nrf-2) inducer, at concentration 5, 10 and 20 uM for 72 hours. Results: We show that chronic, low-dose PFOS exposure promotes proliferation of SW480 and HCT116 cell lines starting at 3 months since the first exposure. The increase in proliferation is associated with upregulation of Cyclin D, pAkt and FASN. We also show that sulforaphane significantly decreases proliferation of HCT116 and SW480 cells, and its efficacy is significantly higher in PFOS exposed CRC cells. The current studies show no effect on sulforaphane on normal colon epithelium cells. Conclusion: Our studies suggest that chronic PFOS exposure promotes proliferation of CRC cells by increasing pro-carcinogenic gene expression and signaling. Furthermore, our findings suggest that supplementation of diet sulforaphane can potentially mitigate the harmful effects from PFOS exposure. Our studies warrant further investigation of the mechanisms behind the effect of PFOS exposure on cancer progression that would guide development of effective intervention strategies to mitigate the harmful effects of the exposure to “forever chemicals”. Citation Format: Jerika Durham, Josiane Weber Tessmann, Bernhard Hennig, Yekaterina Zaytseva. Chronic perfluorooctanesulfonic acid exposure promotes proliferation of colorectal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1478.

Abstract 1480: Perfluorooctanesulfonic acid exposure promotes pathological changes in normal intestinal tissues which may lead to an increased risk of colorectal cancer development

Abstract Introduction: Long-term exposures to per- and polyfluoroalkyl substances (PFAS) have been increasingly linked to negative health outcomes including metabolic disorders, reduced immune responses, and increased risk of cancer. PFOS, one the most frequently detected PFAS in drinking water, is readily absorbed in the GI tract and distributes predominantly to the plasma and liver. Even though recent studies demonstrate that PFOS can cause an imbalance of cecal gut microbiota, alter microbiota diversity, and promote inflammation and gut barrier dysfunction, there is still not much known about the effects of PFOS exposure on normal and pre-malignant intestinal tissues and its contribution to carcinogenesis. Therefore, the goal of this study is to investigate the effects of PFOS on normal (I) and malignant intestinal cells (II). Methods: The effect of PFOS on gene expression profile was assessed by RNAseq analysis in intestinal tissue of C57BL/6 mice. Tumor organoids were established from Apc/VillinCre mice (adenoma models). Organoid cultures, colorectal cancer (CRC) and primary normal intestinal cell lines have been treated with 1μg/ml of PFOS. To access the mechanisms involved in PFOS-induced intestinal alterations, qRT-PCR, western blot, immunofluorescence, cytokine array and metabolomics analysis have been performed. Results: The RNAseq analysis showed that PFOS exposure is associated with transcriptome alterations with exacerbated changes in pathways involved in lipid metabolism, immune system regulation and pro-carcinogenesis signaling. PFOS exposure leads to a significant decrease in expression of 3-hydroxy-3-methylglutaryl-Coa synthase 2 (HMGCS2), a rate limiting ketogenic enzyme, in intestinal tissues. We also showed that PFOS exposure upregulates fatty acid synthase, a key enzyme of de novo lipogenesis, programmed death-ligand, an immune checkpoint inhibitor, and altered the levels of pro-inflammatory cytokines and metabolites. Using HMGCS2 knockout cells, we identified the possible contribution of HMGCS2 in cytokine regulation and activation of oncogenic pathways. Conclusion: In summary, our data suggests that PFOS may induce gastrointestinal pathological changes that can increase the risk of CRC development. Further studies are warranted to determine the functional significance of PFOS-mediated downregulation of HMGCS2 and upregulation of lipid metabolism in intestinal cells. Delineating the effects of PFOS on intestinal epithelium may contribute to development of interventional strategies to eliminate harmful effects of these environmental pollutants. Citation Format: Josiane Weber Tessmann, Jerika Durham, Ryan Goettl, Dang he, Chi Wang, Pan Deng, Bernhard Hennig, Yekaterina Zaytseva. Perfluorooctanesulfonic acid exposure promotes pathological changes in normal intestinal tissues which may lead to an increased risk of colorectal cancer development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1480.

Abstract 756: Differences in composition, diversity, and function of the fecal microbiota of post-menopausal breast cancer patients compared to healthy, age-matched controls

Abstract Gut microbiota are a community of organisms that colonize the intestinal tract with essential roles in immune function, gut epithelial integrity, and metabolite production. Dysbiosis occurs when the gut microbiota environment is negatively altered causing detrimental changes to these functions, which may predispose an individual to breast cancer development. To understand the relationship between dysbiosis and breast cancer development, fecal microbiota samples were collected from 27 post-menopausal breast cancer patients of varying hormone receptor statuses (ER+HER2-, ER+Her2+, ER-HER2+, or ER-Her2-) prior to starting chemotherapeutic treatment. Samples were compared to 25 healthy controls, and all samples underwent 16srRNA sequencing. Samples from breast cancer patients and control groups were compared for significant differences (P&amp;lt;.05) in alpha (within sample) and beta (between sample) diversity. Using the Shannon Index and Generalized Least Squares Model, significant differences in alpha diversity were identified between all breast cancer types vs. controls (P=.0104), and between ER+HER2- breast cancer vs. controls (P=.00153). Healthy controls exhibited a higher mean Shannon Index than breast cancer patients, thus higher within sample diversity. Using principal coordinate analyses, significant differences in beta diversity were identified between all breast cancer types vs. controls (P = .01199), and ER+HER2- breast cancer vs. control (P = .008991). Further analyses identified significant taxa of microbiota with functions related to breast cancer development and progression. Of note, Lachnoclostridium, a genus of bacteria that can produce β-glucuronidase, which can deconjugate estrogen, was increased in all breast cancer types and ER+HER2- breast cancer when compared to controls. Deconjugation of estrogen can cause elevated blood estrogen levels, potentially increasing Estrogen Receptor binding in hormone-receptor-positive breast cancer. Additionally, Akkermansia, a genus implicated in gut barrier dysfunction, was decreased in ER+HER2- patients, while Parvimonas, a tumorigenic cell-cycle regulator, was increased. Elucidating if these effects are causative or reactionary may have important implications for understanding breast cancer etiology. Samples are currently undergoing additional metagenomic analyses using long-read sequencing to identify specific bacteria, viruses, fungi, parasites, and phages that may be contributing to dysbiosis. Overall, this study is the first, to our knowledge, to employ short and long-read sequencing to the fecal samples of untreated postmenopausal breast cancer patients. We provide mechanistic insight into the relationship between microbiota and breast cancer development, with the intent of informing future patient screening and prevention. Citation Format: Nadia Kabbej, Frederick Ashby, Erika Atencio, Erinn Rosenkrantz, Dominique Day, Khloe Dang, Josee Gauthier, Rachel Newsome, John Sommerville, Taqwa Naas, Raad Gharaibeh, Christian Jobin, Amira Quevedo, Coy D. Heldermon. Differences in composition, diversity, and function of the fecal microbiota of post-menopausal breast cancer patients compared to healthy, age-matched controls [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 756.

Inflammation and Gut Barrier Function-Related Genes and Colorectal Cancer Risk in Western European Populations.

Gut barrier dysfunction and related inflammation are known to be associated with the development and progression of colorectal cancer (CRC). We investigated associations of 292 single-nucleotide polymorphisms (SNPs) from 27 genes related to endotoxins/lipopolysaccharide (LPS) sensing and tolerance, mucin synthesis, inflammation, and Crohn's disease with colon and rectal cancer risks. Incident CRC cases (N=1,374; colon=871, rectum=503) were matched 1:1 to controls nested within the European Prospective Investigation into Cancer and Nutrition cohort. Previously measured serum concentrations of gut barrier function and inflammation biomarkers (flagellin/LPS-specific immunoglobulins and C-reactive protein [CRP]) were available for a sub-set of participants (Ncases=1,001; Ncontrols=667). Forty-two unique SNPs from 19 different genes were associated with serum biomarkers at Punadjusted≤0.05 among controls. Among SNPs associated with a gut permeability score, 24 SNPs were in genes related to LPS sensing and mucin synthesis. Nine out of 12 SNPs associated with CRP were in genes related to inflammation or Crohn's disease. TLR4 was associated with colon cancer at the SNP level (nine SNPs, all Punadjusted≤0.04) and at the gene level (Punadjusted≤0.01). TLR4 rs10759934 was associated with rectal cancer but not colon cancer. Similarly, IL10 was associated with rectal cancer risk at a SNP and gene level (both Punadjusted ≤ 0.01), but not colon cancer. Genes and SNPs were selected a priori therefore we present unadjusted P-values. However, no association was statistically significant after multiple testing correction. This large and comprehensive study has identified gut barrier function and inflammation-related genes possibly contributing to CRC risk in European populations and is consistent with potential etiological links between host genetic background, gut barrier permeability, microbial endotoxemia and CRC development.

Amygdalin Alleviates DSS-Induced Colitis by Restricting Cell Death and Inflammatory Response, Maintaining the Intestinal Barrier, and Modulating Intestinal Flora.

Inflammatory bowel disease (IBD) refers to a cluster of intractable gastrointestinal disorders with an undetermined etiology and a lack of effective therapeutic agents. Amygdalin (Amy) is a glycoside extracted from the seeds of apricot and other Rosaceae plants and it exhibits a wide range of pharmacological properties. Here, the effects and mechanisms of Amy on colitis were examined via 16S rRNA sequencing, ELISA, transmission electron microscopy, Western blot, and immunofluorescence. The results showed that Amy administration remarkably attenuated the signs of colitis (reduced body weight, increased disease activity index, and shortened colon length) and histopathological damage in dextran sodium sulfate (DSS)-challenged mice. Further studies revealed that Amy administration significantly diminished DSS-triggered gut barrier dysfunction by lowering pro-inflammatory mediator levels, inhibiting oxidative stress, and reducing intestinal epithelial apoptosis and ferroptosis. Notably, Amy administration remarkably lowered DSS-triggered TLR4 expression and the phosphorylation of proteins related to the NF-κB and MAPK pathways. Furthermore, Amy administration modulated the balance of intestinal flora, including a selective rise in the abundance of S24-7 and a decline in the abundance of Allobaculum, Oscillospira, Bacteroides, Sutterella, and Shigella. In conclusion, Amy can alleviate colitis, which provides data to support the utility of Amy in combating IBD.

Stress-induced changes in cognitive function and intestinal barrier integrity can be ameliorated by venlafaxine and synbiotic supplementations.

Stress profoundly impacts various aspects of both physical and psychological well-being. Our previous study demonstrated that venlafaxine (Vlx) and synbiotic (Syn) treatment attenuated learned fear-like behavior and recognition memory impairment in immobilized-stressed rats. In this study, we further investigated the physical, behavior, and cellular mechanisms underlying the effects of Syn and/or Vlx treatment on brain and intestinal functions in stressed rats. Adult male Wistar rats, aged 8 weeks old were subjected to 14 days of immobilization stress showed a decrease in body weight gain and food intake as well as an increase in water consumption, urinary corticosterone levels, and adrenal gland weight. Supplementation of Syn and/or Vlx in stressed rats resulted in mitigation of weight loss, restoration of normal food and fluid intake, and normalization of corticosterone levels. Behavioral analysis showed that treatment with Syn and/or Vlx enhanced depressive-like behaviors and improved spatial learning-memory impairment in stressed rats. Hippocampal dentate gyrus showed stress-induced neuronal cell death, which was attenuated by Syn and/or Vlx treatment. Stress-induced ileum inflammation and increased intestinal permeability were both effectively reduced by the supplementation of Syn. In addition, Syn and Vlx partly contributed to affecting the expression of the glial cell-derived neurotrophic factor in the hippocampus and intestines of stressed rats, suggesting particularly protective effects on both the gut barrier and the brain. This study highlights the intricate interplay between stress physiological responses in the brain and gut. Syn intervention alleviate stress-induced neuronal cell death and modulate depression- and memory impairment-like behaviors, and improve stress-induced gut barrier dysfunction which were similar to those of Vlx. These findings enhance our understanding of stress-related health conditions and suggest the synbiotic intervention may be a promising approach to ameliorate deleterious effects of stress on the gut-brain axis.

Transcriptomic and metabolomic analysis unveils nanoplastic-induced gut barrier dysfunction via STAT1/6 and ERK pathways

The widespread prevalence of micro and nanoplastics in the environment raises concerns about their potential impact on human health. Recent evidence demonstrates the presence of nanoplastics in human blood and tissues following ingestion and inhalation, yet the specific risks and mechanisms of nanoplastic toxicity remain inadequately understood. In this study, we aimed to explore the molecular mechanisms underlying the toxicity of nanoplastics at both systemic and molecular levels by analyzing the transcriptomic/metabolomic responses and signaling pathways in the intestines of mice after oral administration of nanoplastics. Transcriptome analysis in nanoplastic-administered mice revealed a notable upregulation of genes involved in pro-inflammatory immune responses. In addition, nanoplastics substantially reduced the expression of tight junction proteins, including occludin, zonula occluden-1, and tricellulin, which are crucial for maintaining gut barrier integrity and function. Importantly, nanoplastic administration increased gut permeability and exacerbated dextran sulfate sodium-induced colitis. Further investigation into the underlying molecular mechanisms highlighted significant activation of signaling transsducer and activator of transcription (STAT)1 and STAT6 by nanoplastic administration, which was in line with the elevation of interferon and JAK-STAT pathway signatures identified through transcriptome enrichment analysis. Additionally, the consumption of nanoplastics specifically induced nuclear factor kappa-B (NF-κB) and extracellular signal-regulated kinase (ERK)1/2 signaling pathways in the intestines. Collectively, this study identifies molecular mechanisms contributing to adverse effects mediated by nanoplastics in the intestine, providing novel insights into the pathophysiological consequences of nanoplastic exposure.

Decreased expression of the NLRP6 inflammasome is associated with increased intestinal permeability and inflammation in obesity with type 2 diabetes

BackgroundObesity-associated dysfunctional intestinal permeability contributes to systemic chronic inflammation leading to the development of metabolic diseases. The inflammasomes constitute essential components in the regulation of intestinal homeostasis. We aimed to determine the impact of the inflammasomes in the regulation of gut barrier dysfunction and metabolic inflammation in the context of obesity and type 2 diabetes (T2D).MethodsBlood samples obtained from 80 volunteers (n = 20 normal weight, n = 21 OB without T2D, n = 39 OB with T2D) and a subgroup of jejunum samples were used in a case–control study. Circulating levels of intestinal damage markers and expression levels of inflammasomes as well as their main effectors (IL-1β and IL-18) and key inflammation-related genes were analyzed. The impact of inflammation-related factors, different metabolites and Akkermansia muciniphila in the regulation of inflammasomes and intestinal integrity genes was evaluated. The effect of blocking NLRP6 by using siRNA in inflammation was also studied.ResultsIncreased circulating levels (P < 0.01) of the intestinal damage markers endotoxin, LBP, and zonulin in patients with obesity decreased (P < 0.05) after weight loss. Patients with obesity and T2D exhibited decreased (P < 0.05) jejunum gene expression levels of NLRP6 and its main effector IL18 together with increased (P < 0.05) mRNA levels of inflammatory markers. We further showed that while NLRP6 was primarily localized in goblet cells, NLRP3 was localized in the intestinal epithelial cells. Additionally, decreased (P < 0.05) mRNA levels of Nlrp1, Nlrp3 and Nlrp6 in the small intestinal tract obtained from rats with diet-induced obesity were found. NLRP6 expression was regulated by taurine, parthenolide and A. muciniphila in the human enterocyte cell line CCL-241. Finally, a significant decrease (P < 0.01) in the expression and release of MUC2 after the knockdown of NLRP6 was observed.ConclusionsThe increased levels of intestinal damage markers together with the downregulation of NLRP6 and IL18 in the jejunum in obesity-associated T2D suggest a defective inflammasome sensing, driving to an impaired epithelial intestinal barrier that may regulate the progression of multiple obesity-associated comorbidities.

P023 Serological markers of intestinal barrier function in patients with primary sclerosing cholangitis after liver transplantation

Abstract Background Primary sclerosing cholangitis (PSC) is a chronic cholestatic disease associated with inflammatory bowel disease. Liver transplantation (LT) is the only curative treatment for most patients with PSC. Recurrence of PSC (rPSC) is a common long-term complication after liver transplantation in this patient group, affecting graft survival and overall patient survival. There are several lines of evidence indicating that dysregulation of the microbiome and gut barrier dysfunction are key etiologic factors in the pathogenesis of PSC. The aim of this study was to evaluate serological markers of intestinal barrier function in patients with PSC after LT and in control group, to determine potential biomarkers for rPSC. Methods This is a cross-sectional study of patients after LT for PSC at the Institute for Clinical and Experimental Medicine, Prague. The control group consists of patients who underwent liver transplantation for alcohol-related liver disease and/or hepatocellular carcinoma. The rPSC was assessed by MRCP and/or liver biopsy according to the Mayo criteria. IBD status was assessed by endoscopy, biopsy, and faecal calprotectin. We performed ELISA for Zonulin and Reg3a. The Kruskal-Wallis and Mann-Whitney test were used to evaluate the statistical differences. Results A total of 85 patients were included in the study after LT for PSC and 56 controls. rPSC was detected in 18 (21.18%) patients. IBD was diagnosed in 77 (90.5%) patients, of which 3 (3.9%) were categorised as Crohn’s disease. The remainder, 82 patients, were classified as ulcerative colitis, 41.9% with right-sided predominance and 24.3% with back-wash ileitis. The IBD treatment consisted of 5-ASA in 58 patients, azathioprine in 12 patients, vedolizumab in 5 patients, anti-TNFa in 1 patient and 9 patients were on 10 mg or more of prednisone or equivalent. MayoDAI was evaluated at the time of the visit with mean 1.74 (SD ±2.06). There was a significant difference in Reg3a levels between patients with IBD and control subjects (p&amp;lt;0.05, Figure 1.). No significant difference in Reg3a levels was found between rPSC patients and controls (p=0.3). Interestingly, Zonulin levels were significantly higher in the control group than in PSC patients with or without IBD (p&amp;lt;0.001). No significant difference in Reg3a and Zonulin was found between PSC and rPSC patients and between patients in remission and with active IBD. Conclusion Reg3a was associated with PSC-IBD in patients with PSC after LT, but its association with rPSC is unclear and should be investigated in a prospective setting. Zonulin reached higher levels in the control group.

Atrial natriuretic peptide protects against gut barrier injury through PLC-γ1/ROS feedback loop in rats following traumatic hemorrhagic shock

Introduction The mechanisms underlying the protective effects of atrial natriuretic peptide (ANP) on the gut barrier during traumatic hemorrhagic shock (THS) remain elusive. This study aimed to explore the potential role of ANP in safeguarding against gut barrier dysfunction after THS, focusing on the PLC-γ1/ROS feedback loop. Methods In our THS rat model, we randomly allocated male Sprague-Dawley rats to receive intravenous ANP with or without a concurrent NADPH oxidase/p38 MAPK inhibitor during the shock phase. After 24 h, we assessed circulatory and jejunal ANP, ROS, intestinal tight junction proteins, and apoptosis to evaluate the effects of ANP on the gut barrier and its interplay with intestinal ANP and ROS. Rat small intestinal epithelial cells (IECs) were also treated with ANP and subjected to hypoxia/re-oxygenation injury, with or without PI3K/PLC inhibition, to elucidate the relationship between ANP/ROS signaling and PLC-γ1. Furthermore, we modulated PLC-γ1 expression in these IECs to examine its impact on ROS and ANP production. Results Intravenous ANP administration at 0.025 μg/kg/min during THS significantly increased intestinal ANP and ROS levels at 24 h. ANP treatment enhanced the expression of intestinal tight junction proteins and reduced IEC apoptosis. Inhibition of circulatory ROS diminished intestinal ANP levels, while suppression of circulatory ANP led to a reduction in intestinal ROS. Decreasing PLC-γ1 expression in hypoxia/re-oxygenation-treated IECs resulted in lower ROS and ANP levels, whereas augmenting PLC-γ1 expression did not alter these levels. Additionally, PI3K inhibition markedly decreased PLC-γ1 expression in these cells. Conclusion ANP-induced protection of the intestinal barrier in THS is mediated by an intrinsic PLC-γ1/ROS positive feedback loop. ANP preserves gut barrier integrity and reduces IEC apoptosis through this mechanism. Further studies are warranted to investigate the interaction between IECs and other cellular components within the PLC-γ1/ROS loop.

Canine and Feline Diabetes Mellitus and the Gastrointestinal Tract

Hyperglycemia, the defining feature of diabetes mellitus (DM), is associated with intestinal barrier dysfunction and increased intestinal permeability (IP). Leaky gut syndrome can lead to systemic inflammation, GI infections, and insulin resistance. Studies in animal models and in people have shown that alterations in tight junctions, epithelial cells, and gut microbiota contribute to gut barrier dysfunction in hyperglycemia. Moreover, dysbiosis of the gut microbiome (GM), with reduced diversity and decreased abundance of beneficial bacteria, has been observed in individuals with DM and prediabetes (preDM). Gut dysbiosis may contribute to insulin resistance, inflammation, and IP, thus influencing the development and progression of DM. Furthermore, evidence has been found that exocrine pancreatic dysfunction can exist concurrently with DM, with decreased pancreatic size, immune cell infiltration, and structural changes noted by histology. Both clinical and histopathologic evidence suggest a potential link between exocrine pancreatic abnormalities and the development of DM. Associations are explored between hyperglycemia, gut barrier dysfunction, alterations in the GM, and exocrine pancreatic dysfunction in DM and preDM, emphasizing the potential role of the gut in the pathogenesis of these conditions in dogs and cats.

Melatonin Prevents Alcohol- and Metabolic Dysfunction- Associated Steatotic Liver Disease by Mitigating Gut Dysbiosis, Intestinal Barrier Dysfunction, and Endotoxemia.

Melatonin (MT) has often been used to support good sleep quality, especially during the COVID-19 pandemic, as many have suffered from stress-related disrupted sleep patterns. It is less known that MT is an antioxidant, anti-inflammatory compound, and modulator of gut barrier dysfunction, which plays a significant role in many disease states. Furthermore, MT is produced at 400-500 times greater concentrations in intestinal enterochromaffin cells, supporting the role of MT in maintaining the functions of the intestines and gut-organ axes. Given this information, the focus of this article is to review the functions of MT and the molecular mechanisms by which it prevents alcohol-associated liver disease (ALD) and metabolic dysfunction-associated steatotic liver disease (MASLD), including its metabolism and interactions with mitochondria to exert its antioxidant and anti-inflammatory activities in the gut-liver axis. We detail various mechanisms by which MT acts as an antioxidant, anti-inflammatory compound, and modulator of intestinal barrier function to prevent the progression of ALD and MASLD via the gut-liver axis, with a focus on how these conditions are modeled in animal studies. Using the mechanisms of MT prevention and animal studies described, we suggest behavioral modifications and several exogenous sources of MT, including food and supplements. Further clinical research should be performed to develop the field of MT in preventing the progression of liver diseases via the gut-liver axis, so we mention a few considerations regarding MT supplementation in the context of clinical trials in order to advance this field of research.

Omics analysis of the effect of cold normal saline stress through gastric gavage on LPS induced mice.

Cold stress is a significant environmental stimulus that negatively affects the health, production, and welfare of animals and birds. However, the specific effects of cold stimulation combined with lipopolysaccharide (LPS) on the mouse intestine remain poorly understood. Therefore, we designed this research to explore the effect of cold stimulation + LPS on mice intestine via microbiome and microbiota sequencing. Forty-eight mice were randomly divided into four experimental groups (n = 12): Control (CC), LPS-induced (CL), cold normal saline-induced (MC) and LPS + cold normal saline-induced (ML). Our results showed body weight was similar among different groups of mice. However, the body weight of mice in groups CC and CL were slightly higher compared to those in groups MC and ML. The results of gene expressions reflected that CL and ML exposure caused gut injury and barrier dysfunction, as evident by decreased ZO-1, OCCLUDIN (P < 0.01), and CASPASE-1 (P < 0.01) expression in the intestine of mice. Moreover, we found that cold stress induced oxidative stress in LPS-challenged mice by increasing malondialdehyde (MDA) accumulation and decreasing the antioxidant capacity [glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), total and antioxidant capacity (T-AOC)]. The cold stress promoted inflammatory response by increased IL-1β in mice treated with cold normal saline + LPS. Whereas, microbiome sequencing revealed differential abundance in four phyla and 24 genera among the mouse groups. Metabolism analysis demonstrated the presence of 4,320 metabolites in mice, with 43 up-regulated and 19 down-regulated in CC vs. MC animals, as well as 1,046 up-regulated and 428 down-regulated in ML vs. CL animals. It is Concluded that cold stress enhances intestinal damage by disrupting the balance of gut microbiota and metabolites, while our findings contribute in improving management practices of livestock in during cold seasons.