Intestinal Mucosal Disruption Research Articles

Composition of Human-Associated Gut Microbiota Determines 3-DF and 3-HF Anti-Colitic Activity in IL-10 -/- Mice

Background: Gut bacterial dysbiosis along with intestinal mucosal disruption plays a critical role in inflammatory disorders like ulcerative colitis. Flavonoids and other food bioactives have been studied in mice models as alternative treatments with minimal side effects. However, most of the research has been carried out with mice-native microbiota, which limits the comprehension of the interaction between flavonoids and human-associated bacteria. Hence, the objective of our study was to determine the effect of healthy human-associated microbiota on the anti-colitic activity of diets rich in anthocyanins (3-HF) and phlobaphenes (3-DF). Methods: In this regard, the interleukin (IL)-10 -/- mice model was utilized. Mice were divided into three groups for inoculation with human gut bacteria from three different healthy donors and assigned to four diets. A purified diet (Diet P) and three diets containing 25% near-isogenic lines (NILs) of corn were evaluated. Diets were substituted with NILs expressing only 3-DFs (diet B), only 3-HFs (diet C), and both 3-DF and 3-HF (diet D). Results: In an overall analysis, flavonoid-rich diets did not affect inflammatory markers, microbiota diversity, or gut metabolites, but diets containing anthocyanins improved barrier function parameters. However, when data was segmented by the recipient’s microbiota from different human donors, the diet effects became significant. Furthermore, 3-HFs showed more beneficial effects than 3-DFs across the recipient’s microbiota. Conclusions: Our study suggests that the anti-colitic activity of 3-DF and 3-HF and their gut metabolites depends on the donor’s microbial composition.

Clostridium perfringens in the Intestine: Innocent Bystander or Serious Threat?

The Clostridium perfringens epidemic threatens biosecurity and causes significant economic losses. C. perfringens infections are linked to more than one hundred million cases of food poisoning annually, and 8-60% of susceptible animals are vulnerable to infection, resulting in an economic loss of more than 6 hundred million USD. The enzymes and toxins (>20 species) produced by C. perfringens play a role in intestinal colonization, immunological evasion, intestinal micro-ecosystem imbalance, and intestinal mucosal disruption, all influencing host health. In recent decades, there has been an increase in drug resistance in C. perfringens due to antibiotic misuse and bacterial evolution. At the same time, traditional control interventions have proven ineffective, highlighting the urgent need to develop and implement new strategies and approaches to improve intervention targeting. Therefore, an in-depth understanding of the spatial and temporal evolutionary characteristics, transmission routes, colonization dynamics, and pathogenic mechanisms of C. perfringens will aid in the development of optimal therapeutic strategies and vaccines for C. perfringens management. Here, we review the global epidemiology of C. perfringens, as well as the molecular features and roles of various virulence factors in C. perfringens pathogenicity. In addition, we emphasize measures to prevent and control this zoonotic disease to reduce the transmission and infection of C. perfringens.

Astragalus polysaccharides attenuate chemotherapy-induced immune injury by modulating gut microbiota and polyunsaturated fatty acid metabolism

BackgroundThe damage of chemotherapy drugs to immune function and intestinal mucosa is a common side effect during chemotherapy. Astragalus polysaccharides (APS) exhibit immunomodulatory properties and are recognized for preserving the integrity of the human intestinal barrier. Nevertheless, their application and mechanisms of action in chemotherapy-induced immune damage and intestinal barrier disruption remain insufficiently explored. PurposeThis study delved into investigating how APS mitigates chemotherapy-induced immune dysfunction and intestinal mucosal injury, while also providing deeper insights into the underlying mechanisms. MethodsIn a chemotherapy mice model induced by 5-fluorouracil (5-Fu), the assessment of APS's efficacy encompassed evaluations of immune organ weight, body weight, colon length, and histopathology. The regulation of different immune cells in spleen was detected by flow cytometry. 16S rRNA gene sequencings, ex vivo microbiome assay, fecal microbiota transplantation (FMT), and targeted metabolomics analysis were applied to explore the mechanisms of APS effected on chemotherapy-induced mice. ResultsAPS ameliorated chemotherapy-induced damage to immune organs and regulated immune cell differentiation disorders, including CD4+T, CD8+T, CD19+B, F4/80+CD11B+ macrophages. APS also alleviated colon shortening and upregulated the expression of intestinal barrier proteins. Furthermore, APS significantly restored structure of gut microbiota following chemotherapy intervention. Ex vivo microbiome assays further demonstrated the capacity of APS to improve 5-Fu-induced microbiota growth inhibition and compositional change. FMT demonstrated that the regulation of gut microbiota by APS could promote the recovery of immune functions and alleviate shortening of the colon length. Remarkably, APS significantly ameliorated the imbalance of linoleic acid (LA) and α-linolenic acid in polyunsaturated fatty acid (PUFA) metabolism. Further in vitro experiments showed that LA could promote splenic lymphocyte proliferation. In addition, both LA and DGLA down-regulated the secretion of NO and partially up-regulated the percentage of F4/80+CD11B+CD206+ cells. ConclusionAPS can effectively ameliorate chemotherapy-induced immune damage and intestinal mucosal disruption by regulating the composition of the gut microbiota and further restoring PUFA metabolism. These findings indicate that APS can serve as an adjuvant to improve the side effects such as intestinal and immune damage caused by chemotherapy.

Betulinic Acid Ameliorates the T-2 Toxin-Triggered Intestinal Impairment in Mice by Inhibiting Inflammation and Mucosal Barrier Dysfunction through the NF-κB Signaling Pathway.

T-2 toxin, a trichothecene mycotoxin produced by Fusarium, is widely distributed in crops and animal feed and frequently induces intestinal damage. Betulinic acid (BA), a plant-derived pentacyclic lupane-type triterpene, possesses potential immunomodulatory, antioxidant and anti-inflammatory biological properties. The current study aimed to explore the protective effect and molecular mechanisms of BA on intestinal mucosal impairment provoked by acute exposure to T-2 toxin. Mice were intragastrically administered BA (0.25, 0.5, or 1 mg/kg) daily for 2 weeks and then injected intraperitoneally with T-2 toxin (4 mg/kg) once to induce an intestinal impairment. BA pretreatment inhibited the loss of antioxidant capacity in the intestine of T-2 toxin-treated mice by elevating the levels of CAT, GSH-PX and GSH and reducing the accumulation of MDA. In addition, BA pretreatment alleviated the T-2 toxin-triggered intestinal immune barrier dysregulation by increasing the SIgA level in the intestine at dosages of 0.5 and 1 mg/kg, increasing IgG and IgM levels in serum at dosages of 0.5 and 1 mg/kg and restoring the intestinal C3 and C4 levels at a dosage of 1 mg/kg. BA administration at a dosage of 1 mg/kg also improved the intestinal chemical barrier by decreasing the serum level of DAO. Moreover, BA pretreatment improved the intestinal physical barrier via boosting the expression of ZO-1 and Occludin mRNAs and restoring the morphology of intestinal villi that was altered by T-2 toxin. Furthermore, treatment with 1 mg/kg BA downregulated the expression of p-NF-κB and p-IκB-α proteins in the intestine, while all doses of BA suppressed the pro-inflammatory cytokines expression of IL-1β, IL-6 and TNF-α mRNAs and increased the anti-inflammatory cytokine expression of IL-10 mRNA in the intestine of T-2 toxin-exposed mice. BA was proposed to exert a protective effect on intestinal mucosal disruption in T-2 toxin-stimulated mice by enhancing the intestinal antioxidant capacity, inhibiting the secretion of inflammatory cytokines and repairing intestinal mucosal barrier functions, which may be associated with BA-mediated inhibition of the NF-κB signaling pathway activation.

Keratinocyte growth factor ameliorates mycophenolate mofetil-induced intestinal barrier disruption in mice

ObjectivesAlthough mycophenolate mofetil-induced (MMF) effectively improves long-term graft survival, the gastrointestinal (GI) side effects due to MMF-induced GI barrier damage limit its use in clinic. Keratinocyte growth factor (KGF) plays a crucial role in the intestinal protection and repair process. This study is designed to investigate the protective effect of KGF on MMF-induced intestinal mucosal barrier disruption and the potential mechanism. MethodsThirty adult male C57BL/6 mice were assigned to one of the following groups: the MMF group, the MMF + KGF group, and the control group (n = 10 in each group). Animals in the MMF group received MMF (500 mg/kg) by gavage once daily for 15 consecutive days; animals in the MMF + KGF group received MMF (500 mg/kg) by gavage and KGF (5 mg/kg) by intraperitoneal injection once daily for 15 consecutive days; and control mice were given an equal volume of vehicle during the 15-day experimental period. In each group, intestinal paracellular permeability, histopathological changes and shifts in tight junction (TJ) protein were evaluated; further, proliferation and apoptosis of intestinal epithelial cells (IECs) were assessed, and intraepithelial lymphocytes (IELs) were isolated and analyzed by flow cytometry. ResultsMMF caused intestinal mucosal injury, increased intestinal mucosal permeability, and altered expression of TJ protein. Moreover, MMF treatment inhibited IEC proliferation and increased apoptosis. MMF treatment resulted in a lower proportion of γδ+ T cells in IELs (γδ+ IELs). Conversely, concurrent administration of KGF with MMF effectively alleviated MMF-induced intestinal mucosal disruption, inhibited the increase in intestinal permeability, and maintained TJ protein expression. KGF also reversed the MMF-mediated inhibition of proliferation and promotion of apoptosis in IECs. In addition, KGF significantly enhanced the proportion of γδ+ IELs. ConclusionOur findings suggest that MMF induces intestinal epithelial barrier disruption in mice. KGF may play a protective role to ameliorate the disruption and provide a therapeutic intervention for gastrointestinal disorders induced by MMF.

Methamphetamine-induced alterations in intestinal mucosal barrier function occur via the microRNA-181c/ TNF-α/tight junction axis

An enterogenic infection occurs when intestinal mucosal disruption is followed by the invasion of intestinal bacteria into the blood and distant organs, which can result in severe diseases or even death. Our previous study using Rhesus monkeys as an in vivo model revealed that methamphetamine (MA) induced intestinal mucosal barrier damage, which poses a high risk of enterogenic infection. However, how methamphetamine causes intestinal mucosal barrier damage remains largely unknown. In this study, we employed an in vitro model, and found that MA treatment could inhibit the expression of miR-181c, which directly targets and regulates TNF-α, and ultimately induces apoptosis and damages the intestinal barrier. Moreover, we measured TNF-α serum levels as well as the intestinal mucosal barrier damage indicators (diamine oxidase, d-lactic acid, and exotoxin) and found that their levels were significantly higher in MA-dependents than in healthy controls (P < 0.001). To the best of our knowledge, this is the first report evidencing that miR-181c is involved in MA-induced intestinal barrier injury via TNF-α regulation, which introduces novel potential therapeutic targets for MA-dependent intestinal diseases.

Dietary leonurine hydrochloride supplementation attenuates lipopolysaccharide challenge-induced intestinal inflammation and barrier dysfunction by inhibiting the NF-κB/MAPK signaling pathway in broilers.

This study was performed to evaluate the beneficial effects of dietary leonurine hydrochloride (LH) supplementation on intestinal morphology and barrier integrity and further illuminate its underlying antioxidant and immunomodulatory mechanisms in lipopolysaccharide (LPS)-treated broilers. A total of 120 1-d-old male broilers (Ross 308) were assigned to 4 treatment groups with 6 replicates of 5 birds per cage. The experiment was designed in a 2 × 2 factorial arrangement with LH (0 or 120 mg/kg) and LPS (injection of saline or 1.5 mg/kg body weight) as treatments. On days 14, 16, 18, and 20 of the trial, broilers were intraperitoneally injected with LPS or physiological saline. Compared with the control group, LPS-challenged broilers showed impaired growth performance (P < 0.05) from day 15 to day 21 of the trial, increased serum diamine oxidase (DAO) and D-lactic acid (D-LA) levels coupled with reduced glutathione (GSH) content and total superoxide dismutase (T-SOD) activity (duodenal and jejunal mucosa), reduced malondialdehyde (MDA) content (duodenal, jejunal, and ileal mucosa), and compromised morphological structure of the duodenum and jejunum. Additionally, LPS challenge increased (P < 0.05) the mRNA expression of proinflammatory cytokine genes and reduced tight junction (TJ) protein expression in the jejunum. However, dietary LH prevented LPS-induced reductions in average daily gain (ADG) and average daily feed intake (ADFI) in broilers. It also alleviated LPS challenge-induced increases in serum DAO levels, MDA content (duodenal and jejunal mucosa), and jejunal crypt depth (P < 0.05) but reduced villus height, GSH content (jejunal mucosa), and T-SOD activity (duodenal and jejunal mucosa) (P < 0.05). Additionally, LH supplementation significantly downregulated the mRNA expression of nuclear factor (NF)-κB, cyclooxygenase-2 (COX-2), and proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and upregulated the mRNA expression of zonula occludens-1 (ZO-1) and Occludin in the jejunal mucosa induced by LPS (P < 0.05). On the other hand, LH administration prevented LPS-induced activation of the p38, extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinases (MAPKs) and attenuated IkB alpha (IκBα) phosphorylation and nuclear translocation of NF-κB (p65) in the jejunal mucosa. In conclusion, dietary LH supplementation attenuates intestinal mucosal disruption mainly by accelerating the expression of TJ proteins and inhibiting activation of the NF-κB/MAPK signaling pathway.

Alginate oligosaccharide alleviates enterotoxigenic Escherichia coli-induced intestinal mucosal disruption in weaned pigs.

Alginate oligosaccharide (AOS) is a non-toxic, non-immunogenic, non-carcinogenic and biodegradable product generated by depolymerisation of alginate, and exhibits various salutary properties. The present study was designed to evaluate whether AOS supplementation could attenuate enterotoxigenic Escherichia coli (ETEC)-induced intestinal mucosal injury in weaned pigs. Twenty-four weaned pigs were randomly assigned to three treatments: (1) non-challenged control; (2) ETEC-challenged control; and (3) ETEC challenge + AOS treatment (100 mg kg-1). On day 12, pigs in the non-challenged group were orally infused with sterilised Luria-Bertani culture while pigs in other groups were orally infused with ETEC (2.6 × 1011 colony-forming units). At 3 days after the challenge, all pigs were orally administered d-xylose at 0.1 g per kg body weight and then euthanised 1 h later to obtain serum and intestinal mucosa samples. Our results showed that ETEC infection both reduced (P < 0.05) the villus height and proportion of epithelial cells in the S phase and elevated (P < 0.05) the percentage of total apoptotic epithelial cells in the jejunum and ileum; these deleterious effects caused by ETEC were alleviated (P < 0.05) by supplemental AOS. Meanwhile, AOS ingestion attenuated (P < 0.05) not only the up-regulated tumour necrosis factor receptor 1 (TNFR1), cysteinyl aspartate-specific protease-3 (caspase-3), -8 and -9 transcriptions, as well as the enhanced caspase activities (caspase-3, -8 and -9), but also the down-regulated cyclin E1 and cyclin-dependent kinase 2 (CDK2) transcriptions in jejunal and ileal mucosae, caused by the ETEC challenge. In conclusion, it is possible that the protective effects of AOS against ETEC-induced intestinal mucosal disruption in weaned pigs are associated with the restrained enterocyte death, by reducing both mitochondria-dependent and TNFR1-dependent apoptosis and the accelerated enterocyte proliferation, via enhancing the cyclin E-CDK2 complex formation.

The gut in trauma.

The purpose of this review is to describe established and emerging mechanisms of gut injury and dysfunction in trauma, describe emerging strategies to improve gut dysfunction, detail the effect of trauma on the gut microbiome, and describe the gut-brain connection in traumatic brain injury. Newer data suggest intraluminal contents, pancreatic enzymes, and hepatobiliary factors disrupt the intestinal mucosal layer. These mechanisms serve to perpetuate the inflammatory response leading to multiple organ dysfunction syndrome (MODS). To date, therapies to mitigate acute gut dysfunction have included enteral nutrition and immunonutrition; emerging therapies aimed to intestinal mucosal layer disruption, however, include protease inhibitors such as tranexamic acid, parenteral nutrition-supplemented bombesin, and hypothermia. Clinical trials to demonstrate benefit in humans are needed before widespread applications can be recommended. Despite resuscitation, gut dysfunction promotes distant organ injury. In addition, postresuscitation nosocomial and iatrogenic 'hits' exaggerate the immune response, contributing to MODS. This was a provocative concept, suggesting infectious and noninfectious causes of inflammation may trigger, heighten, and perpetuate an inflammatory response culminating in MODS and death. Emerging evidence suggests posttraumatic injury mechanisms, such as intestinal mucosal disruption and shifting of the gut microbiome to a pathobiome. In addition, traumatic brain injury activates the gut-brain axis and increases intestinal permeability.

Effect of Candida albicans on Intestinal Ischemia-reperfusion Injury in Rats.

Background:Inflammation is supposed to play a key role in the pathophysiological processes of intestinal ischemia-reperfusion injury (IIRI), and Candida albicans in human gut commonly elevates inflammatory cytokines in intestinal mucosa. This study aimed to explore the effect of C. albicans on IIRI.Methods:Fifty female Wistar rats were divided into five groups according to the status of C. albicans infection and IIRI operation: group blank and sham; group blank and IIRI; group cefoperazone plus IIRI; group C. albicans plus cefoperazone and IIRI (CCI); and group C. albicans plus cefoperazone and sham. The levels of inflammatory factors tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β, and diamine oxidase (DAO) measured by enzyme-linked immunosorbent assay were used to evaluate the inflammation reactivity as well as the integrity of small intestine. Histological scores were used to assess the mucosal damage, and the C. albicans blood translocation was detected to judge the permeability of intestinal mucosal barrier.Results:The levels of inflammatory factors TNF-α, IL-6, and IL-1β in serum and intestine were higher in rats undergone both C. albicans infection and IIRI operation compared with rats in other groups. The levels of DAO (serum: 44.13 ± 4.30 pg/ml, intestine: 346.21 ± 37.03 pg/g) and Chiu scores (3.41 ± 1.09) which reflected intestinal mucosal disruption were highest in group CCI after the operation. The number of C. albicans translocated into blood was most in group CCI ([33.80 ± 6.60] ×102 colony forming unit (CFU)/ml).Conclusion:Intestinal C. albicans infection worsened the IIRI-induced disruption of intestinal mucosal barrier and facilitated the subsequent C. albicans translocation and dissemination.

Supplemental dietary L-arginine attenuates intestinal mucosal disruption during a coccidial vaccine challenge in broiler chickens.

The present study investigated the effects of dietary arginine (Arg) supplementation on intestinal structure and functionality in broiler chickens subjected to coccidial challenge. The present study was a randomised complete block design employing a 3×2 factorial arrangement (n 8) with three dietary concentrations of Arg (11·1, 13·3 and 20·2g/kg) with or without coccidial vaccine challenge (unchallenged and coccidial challenge). On day 14, birds were orally administered with coccidial vaccine or saline. On day 21, birds were killed to obtain jejunal tissue and mucosal samples for histological, gene expression and mucosal immunity measurements. Within 7d of the challenge, there was a decrease in body-weight gain and feed intake, and an increase in the feed:gain ratio (P<0·05). Jejunal inflammation was evidenced by villus damage, crypt dilation and goblet cell depletion. Coccidial challenge increased mucosal secretory IgA concentration and inflammatory gene (iNOS, IL-1β, IL-8 and MyD88) mRNA expression levels (P<0·05), as well as reduced jejunal Mucin-2, IgA and IL-1RI mRNA expression levels (P<0·05). Increasing Arg concentration (1) increased jejunal villus height (P<0·05) and linearly increased jejunal crypt depth (P<0·05); (2) quadratically increased mucosal maltase activity (P<0·05) and linearly decreased mucosal secretory IgG concentration (P<0·05) within the coccidiosis-challenged groups; and (3) linearly decreased jejunal Toll-like receptor 4 (TLR4) mRNA expression level (P<0·05) within the coccidiosis-challenged groups. The mRNA expression of mechanistic target of rapamycin (mTOR) complex 1 pathway genes (mTOR and RPS6KB1) and the anti-apoptosis gene Bcl-2 quadratically responded to increasing dietary Arg supplementation (P<0·05). These results indicate that dietary Arg supplementation attenuates intestinal mucosal disruption in coccidiosis-challenged chickens probably through suppressing TLR4 and activating mTOR complex 1 pathways.

Dietary arginine supplementation alleviates intestinal mucosal disruption induced by Escherichia coli lipopolysaccharide in weaned pigs

This study evaluated whether arginine (Arg) supplementation could attenuate gut injury induced by Escherichia coli lipopolysaccharide (LPS) challenge through an anti-inflammatory role in weaned pigs. Pigs were allotted to four treatments including: (1) non-challenged control; (2) LPS-challenged control; (3) LPS+0.5 % Arg; (4) LPS+1.0 % Arg. On day 16, pigs were injected with LPS or sterile saline. At 6 h post-injection, pigs were killed for evaluation of small intestinal morphology and intestinal gene expression. Within 48 h of challenge, 0.5 % Arg alleviated the weight loss induced by LPS challenge (P = 0.025). In all three intestinal segments, 0.5 or 1.0 % Arg mitigated intestinal morphology impairment (e.g. lower villus height and higher crypt depth) induced by LPS challenge (P < 0.05), and alleviated the decrease of crypt cell proliferation and the increase of villus cell apoptosis after LPS challenge (P < 0.01). The 0.5 % Arg prevented the elevation of jejunal IL-6 mRNA abundance (P = 0.082), and jejunal (P = 0.030) and ileal (P = 0.039) TNF-alpha mRNA abundance induced by LPS challenge. The 1.0 % Arg alleviated the elevation of jejunal IL-6 mRNA abundance (P = 0.053) and jejunal TNF-alpha mRNA abundance (P = 0.003) induced by LPS challenge. The 0.5 % Arg increased PPARgamma mRNA abundance in all three intestinal segments (P < 0.10), and 1.0 % Arg increased duodenal PPARgamma mRNA abundance (P = 0.094). These results indicate that Arg supplementation has beneficial effects in alleviating gut mucosal injury induced by LPS challenge. Additionally, it is possible that the protective effects of Arg on the intestine are associated with decreasing the expression of intestinal pro-inflammatory cytokines through activating PPARgamma expression.

Eimeria dispersa, E. adenoeides, and E. meleagrimitis: Intestinal Mucosal Disruption in Turkeys as Seen with Scanning Electron Microscopy

Tissues from the digestive tract of turkeys infected with Eimeria dispersa, E. adenoeides, or E. meleagrimitis were compared with tissues from uninfected controls as seen with light microscopy (LM) and scanning electron microscopy (SEM). Six regions were examined--duodenum, jejunum, ileum, cecal neck, cecal pouch, and large intestine. Although LM showed large numbers of E. dispersa in the epithelial cells, SEM usually showed little mucosal disruption. Occasionally the surface of duodenum and jejunum, as seen with SEM, was convoluted and disrupted. In one bird, some parasite-induced damage was found with either LM or SEM in the duodenum and jejunum of turkeys given E. adenoeides oocysts. Although LM showed parasites in the rest of the digestive tract of all E. adenoeides infected birds, SEM showed only a localized sloughing of the mucosa in the cecal pouch. The most extensive damage to the villar surface was caused by E. meleagrimitis. Infections often disrupted the villar tips, especially in the small intestine and cecal neck. Localized areas of pitting were often found on individual villi. All 3 species produced oocyst extrusion sites, especially in the ileum and the ceca.