Small Intestinal Epithelial Barrier Research Articles

PSI-28 Effect of supplementing a Bacillus spp.-based probiotic on intestinal tight junction proteins expression and abundance of selected microorganisms in heat stressed pigs

Abstract The maintenance of small intestine epithelial barrier function, depending in part on tight junction proteins (TJP), prevents the system from invasion of undesired materials but may become altered in heat stressed pigs. Heat stress (HS) also appears to modify the composition of intestinal microbiota that, combined with a weak barrier, may cause health deterioration of pigs. Probiotics, in contrast, can help animals to maintain a healthy intestinal environment. A study, conducted with pigs [n = 80; body weight (BW) = 21.6 ± 3.4 kg], analyzed the effect of HS and the supplementation of a Bacillus spp-based probiotic on gene expression of the TJP occludin, claudins, and TJP1 in jejunum and ileum. Abundance of Lactobacillus sp., Bifidobacterium sp., Bacillus subtilis and E. coli in ileal content was also analyzed. Treatments were thermal neutral (TN) pigs fed a control diet without probiotic (TN-C) or with 0.05% probiotic (TN-P), and HS pigs fed a control without probiotic (HS-C) or with 0.05% probiotic (HS-P). The control diet was based on wheat and soybean meal, added with free Lys, Thr, Met, and Val. Feed and water were freely available during the 21-d study. At termination, six pigs per treatment were sacrificed and samples from jejunum and ileum tissue were collected to analyze TJP gene expression; ileal content was collected to analyze abundance of intestinal microorganisms. Ambient temperature inside TN and HS rooms ranged from 19 to 25°C and 30 to 38.5°C, respectively. In jejunum, claudin2 expression was greater in TN-P than in TN-C (P = 0.05) but there was no effect of HS. In ileum, HS increased claudin3 but decreased occludin gene expression (P < 0.05). HS did not affect TJP1gene expression (P > 0.10). Probiotic supplementation did not affect gene expression of TJP (P > 0.10). Relative to TN-C pigs, abundance of Lactobacillus sp. and Bifidobacterium sp. tended to decrease in HS-C pigs (P < 0.10), and that of Bifidobacterium sp. decreased in HS-P pigs (P < 0.05). Abundance of E. coli tended to be greater (P < 0.10) in both HS-C and HS-P pigs, than in the TN-C pigs. Abundance of Bacillus sp. was greater (P < 0.01) in HS pigs fed the diet supplemented with the probiotic, compared with the TN-C (P < 0.01) and HS-C (P < 0.05) pigs. In conclusion, these data indicate that HS affects TJP gene expression and composition of intestinal microbiota, but supplementing 0.05% of a probiotic based on Bacillus spp. did not affect the abundance of measured microbiota except for Bacillus sp. under HS conditions.

Mulberry Leaf-Derived Morin Activates β-Catenin by Binding to Frizzled7 to Promote Intestinal Stem Cell Expansion upon Heat-Stable Enterotoxin b Injury.

Intestinal stem cells (ISCs) sustain epithelial renewal by dynamically altering behaviors of proliferation and differentiation in response to various nutrition and stress inputs. However, how ISCs integrate bioactive substance morin cues to protect against heat-stable enterotoxin b (STb) produced by Escherichia coli remains an uncertain question with implications for treating bacterial diarrhea. Our recent work showed that oral mulberry leaf-derived morin improved the growth performance in STb-challenged mice. Furthermore, morin supplementation reinstated the impaired small-intestinal epithelial structure and barrier function by stimulating ISC proliferation and differentiation as well as supporting intestinal organoid expansion ex vivo. Importantly, the Wnt/β-catenin pathway, an ISC fate commitment signal, was reactivated by morin to restore the jejunal crypt-villus architecture in response to STb stimulation. Mechanically, the extracellular morin-initiated β-catenin axis is dependent or partially dependent on the Wnt membrane receptor Frizzled7 (FZD7). Our data reveal an unexpected role of leaf-derived morin, which represents molecular signaling targeting the FZD7 platform instrumental for controlling ISC regeneration upon STb injury.

Tributyrin Supplementation Rescues Chronic-Binge Ethanol-Induced Oxidative Stress in the Gut-Lung Axis in Mice.

Excessive alcohol consumption increases the severity and worsens outcomes of pulmonary infections, often due to oxidative stress and tissue damage. While the mechanism behind this relationship is multifaceted, recent evidence suggests ethanol-induced changes to the gut microbiome impact the gut-lung axis. To assess this, a chronic-binge ethanol feeding mouse model was used to determine how ethanol altered the gut microbiome, small intestinal epithelial barrier, and immune responses, as well as neutrophil abundance and oxidative stress in the lungs, and how supporting gut health with tributyrin supplementation during chronic-binge ethanol exposure affected these responses. We found that ethanol consumption altered gut bacterial taxa and metabolic processes, distorted small intestinal immune responses, and induced both bacteria and endotoxin translocation into the lymphatic and circulatory systems. These changes were associated with increased neutrophil (Ly6G) presence and markers of oxidative stress, lipocalin-2 and myeloperoxidase, in the lungs. Importantly, tributyrin supplementation during ethanol exposure rescued gut bacterial function (p < 0.05), small intestinal barrier integrity, and immune responses, as well as reducing both Ly6G mRNA (p < 0.05) and lipocalin-2 mRNA (p < 0.01) in the lungs. These data suggest ethanol-associated disruption of gut homeostasis influenced the health of the lungs, and that therapeutics supporting gut health may also support lung health.

A12 ROLE OF INTESTINAL EPITHELIAL HNF4A IN PROTECTING AGAINST ACUTE INFLAMMATORY STIMULI

Abstract Background Inflammatory bowel disease is a group of chronic resulting from complex interactions between host susceptibility genes, the host microbiome, the immune system, and environmental triggers. The gastrointestinal epithelium acts as a barrier against harmful stimuli, and defects in its integrity are a precursor for the development of IBD. Our laboratory has shown that the conditional deletion of Hnf4a in the mouse intestinal epithelium leads to chronic intestinal inflammation. However, the functional role of HNF4A on epithelial barrier integrity is still controversial. Aims To evaluate the impact of Hnf4a deletion on barrier integrity during acute inflammation. Methods We used a tamoxifen-inducible CreER-loxP system to delete Hnf4a in the adult intestinal epithelium (Hnf4aΔIEC-ind). Intestinal permeability was assessed in Hnf4aΔIEC-ind and control mice in the collected serum after oral gavage of FITC-dextran. Mice were infected with an invasion-attenuated strain of Salmonella Typhimurium (SB103). S. Typhimurium loads were scored in the feces, liver, and spleen tissue. Histological analysis was carried out by various staining. Also, we used a model of T-cell-induced enteropathy triggered by a T-cell activating monoclonal anti-CD3ε Ab (145-2C11). Mice were assessed for clinical signs of enteropathy and sacrificed 1-, 3-, and 5 days post-injection. Gene expression of selected targets was studied by RT-qPCR. Results FITC-dextran assay showed a significant increase of the intestinal permeability in uninfected mutant mice compared to controls. In contrast, an oral infection with an invasion-deficient S. Typhimurium strain did not differentially impact in tissue bacterial loads or epithelial damage between groups. Likewise, the loss of epithelial HNF4A led to increased Muc2 transcripts expression in the ileum of infected mutant mice but not in the colon. Histological examinations at four days post-infection showed an elevated number and size of goblet cells in the ileal crypts of mutant mice. Bacterial localization using the general bacterial probe EUB388-cy3 (red) staining showed that infected mutant mice tended to enhance barrier mucus layer thickness compared to the controls. On the contrary, acute T cell activation with anti-CD3 mAb induced a significant increase of mRNA expression of Cxcl1 in the small intestine of mutant mice. H&amp;E staining showed elongated ileal crypts in mutant mice compared to controls after anti-CD3 injection. Conclusions Altogether, these results support that HNF4A could play a crucial adaptive role in modulating the small intestine epithelial barrier function and controlling the immune system during acute inflammatory stress. Funding Agencies CCC, CIHR

Utility of human induced pluripotent stem cell-derived small intestinal epithelial cells for pharmacokinetic, toxicological, and immunological studies

The small intestine, which plays a crucial role in the absorption and metabolism of drugs and foods, serves as a target organ for drug-induced toxicity and immune interactions with functional foods and intestinal bacteria. Current alternative models of the human small intestine, such as Caco-2 cells and experimental animals, have limitations due to variations in the expression levels of metabolic enzymes, transporters, and receptors. This study presents investigations into the utility of human induced pluripotent stem cell-derived small intestinal epithelial cells (hiSIECs) for pharmacokinetic, toxicological, and immunological studies, respectively. While hiSIECs displayed small intestinal epithelial cell characteristics and barrier function, they demonstrated pharmacokinetic properties such as cytochrome P450 3A4/5 activity equivalent to human primary enterocytes and stable P-glycoprotein activity. These cells also demonstrated potential for assessing two forms of intestinal toxicity caused by anticancer drugs and gamma-secretase inhibitors, displaying immune responses mediated by toll-like and fatty acid receptors while serving as an inflammatory gut model through the addition of tumor necrosis factor alpha and interferon gamma. Overall, hiSIECs hold promise as an in vitro model for assessing pharmacokinetics, toxicity, and effects on the intestinal immunity of pharmaceuticals, functional foods, supplements, and intestinal bacteria.

Sustained oral intake of nano-iron oxide perturbs the gut-liver axis

Nanomaterial have shown excellent properties in the food industry. Although iron oxides are often considered safe and widely used as food additives, the toxicity of nano‑iron oxide remains unclear. Here we established a subchronic exposure mouse model by gavage, tested the biodistribution of nano‑iron oxide, and explored the mechanism of liver injury caused by it through disturbance of the gut-liver axis. Oral intake of nano‑iron oxide will likely disrupt the small intestinal epithelial barrier, induce hepatic lipid metabolism disorders through the gut–liver axis, and cause hepatic damage accompanied with hepatic iron deposition. Nano‑iron oxide mainly caused hepatic lipid metabolism disorder by perturbing glycerophospholipid metabolism and the sphingolipid metabolism pathways, with the total abundance of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) tending to decrease while that of triglyceride tended to increase, in a time- and dose-dependent manner. The imbalanced lipid homeostasis could cause damage via membrane disruption, lipid accumulation, and lipotoxicity. This data provides information about the subchronic toxicity of nano‑iron oxide, highlights the importance of gut-liver axis in the hepatotoxicity.

Lonicera caerulea polyphenols inhibit fat absorption by regulating Nrf2-ARE pathway mediated epithelial barrier dysfunction and special microbiota

ScopeHigh-fat diet (HFD) induces imbalance in the small intestine environment, where fat digestion and absorption mainly take place. This study aimed to elucidate the mechanisms by which Lonicera caerulea polyphenols (LCP) might inhibit fat absorption, from the perspective of small intestine microbiota and epithelial barrier integrity. Methods and resultsMale Sprague-Dawley rats were given HFD with or without co-administration of LCP for 8 weeks. The results showed that LCP supplementation significantly decreased the levels of serum triglycerides (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C), and increased the contents of fecal sterols, in HFD rats. LCP also inhibited the dysfunction of the small intestine epithelial barrier, via alleviating the oxidative stress activated by Nrf2-ARE pathway, and by modulating the expressions of pro-inflammatory factors such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), cyclooxygenase-2 (COX-2), nuclear factor kappa-B p65 (NF-κB p65) and inducible nitric oxide synthase (iNOS) in the small intestine. Additionally, LCP administration restored the balance in small intestine microbiota and increased the abundance of the specific bacteria, such as Lactobacillus, involved in fat absorption. ConclusionOur results demonstrated that LCP may be beneficial to inhibit fat absorption. The mechanism seems to be associated with the protection of the epithelial barrier integrity and the modulation of specific bacteria in the small intestine.

Zinc-methionine acts as an anti-diarrheal agent by protecting the intestinal epithelial barrier in postnatal Holstein dairy calves

This study compared the effects of supplementation of postnatal Holstein dairy calves with low doses of zinc-methionine (Zn-Met) or zinc oxide (ZnO) on growth performance, diarrhea incidence, and the integrity of the small intestinal epithelial barrier. Twenty-four male newborn Holstein dairy calves with similar body weight (42.0 ± 1.2 kg) received raw milk and starter containing zinc at 4.05 mg/kg and 176 mg/kg dry matter, respectively. All animals were randomly allocated to one of three groups (n = 8 per group): a control group (CON, without extra zinc supplementation), a Zn-Met group (receiving 455 mg of Zn-Met per day, equivalent to 80 mg of zinc per day), or a ZnO group (receiving 103 mg of ZnO per day, equivalent to 80 mg of zinc per day). The experiment lasted for 14 days. Zn-Met and ZnO were mixed with milk and fed to the calves. Body weight, height, length, and heart girth were measured on the morning of days 1, 7, and 15. Feed intake and fecal scores were recorded daily during the experimental period. Blood samples were collected on day 15 before morning feeding. Thereafter, the animals were euthanized and their small intestines were collected for examination of intestinal morphology and the expression levels of mRNAs encoding jejunal mucosal tight junction (TJ) proteins. The two different sources of zinc did not influence growth performance or diarrhea incidence in dairy calves during days 1–7 or 1–14 after birth. However, Zn-Met supplementation reduced the diarrhea incidence (35.7 % [Zn-Met] vs. 58.9 % [CON]) and improved the average daily gain (ADG) (500 g/d [Zn-Met] vs. 422 g/d [CON]) and feed efficiency (feed-to-gain ratio: 2.05 [Zn-Met] vs. 2.47 [CON]) significantly during the second week after birth (P < 0.05). Supplementation with Zn-Met improved the integrity of the intestinal mucosa barrier, as indicated by increases in the height of the ileal villi and the expression levels of mRNAs encoding jejunal mucosal TJ proteins (claudin-1, occludin, and zonula occludens protein-1), as well as a reduction in serum D-lactate concentration (P < 0.05). By contrast, no significant differences in the parameters examined were observed between the ZnO and CON groups. Overall, these findings suggest that Zn-Met supplementation lowers the incidence of diarrhea in postnatal Holstein dairy calves by reducing intestinal permeability, which sheds light on the effectiveness of zinc application as a potential treatment for diarrhea during early life calf rearing.

Extracellular vesicles derived from mesenchymal stromal cells mitigate intestinal toxicity in a mouse model of acute radiation syndrome

BackgroundHuman exposure to high doses of radiation resulting in acute radiation syndrome and death can rapidly escalate to a mass casualty catastrophe in the event of nuclear accidents or terrorism. The primary reason is that there is presently no effective treatment option, especially for radiation-induced gastrointestinal syndrome. This syndrome results from disruption of mucosal barrier integrity leading to severe dehydration, blood loss, and sepsis. In this study, we tested whether extracellular vesicles derived from mesenchymal stromal cells (MSC) could reduce radiation-related mucosal barrier damage and reduce radiation-induced animal mortality.MethodsHuman MSC-derived extracellular vesicles were intravenously administered to NUDE mice, 3, 24, and 48 h after lethal whole-body irradiation (10 Gy). Integrity of the small intestine epithelial barrier was assessed by morphologic analysis, immunostaining for tight junction protein (claudin-3), and in vivo permeability to 4 kDa FITC-labeled dextran. Renewal of the small intestinal epithelium was determined by quantifying epithelial cell apoptosis (TUNEL staining) and proliferation (Ki67 immunostaining). Statistical analyses were performed using one-way ANOVA followed by a Tukey test. Statistical analyses of mouse survival were performed using Kaplan-Meier and Cox methods.ResultsWe demonstrated that MSC-derived extracellular vesicle treatment reduced by 85% the instantaneous mortality risk in mice subjected to 10 Gy whole-body irradiation and so increased their survival time. This effect could be attributed to the efficacy of MSC-derived extracellular vesicles in reducing mucosal barrier disruption. We showed that the MSC-derived extracellular vesicles improved the renewal of the small intestinal epithelium by stimulating proliferation and inhibiting apoptosis of the epithelial crypt cells. The MSC-derived extracellular vesicles also reduced radiation-induced mucosal permeability as evidenced by the preservation of claudin-3 immunostaining at the tight junctions of the epithelium.ConclusionsMSC-derived extracellular vesicles promote epithelial repair and regeneration and preserve structural integrity of the intestinal epithelium in mice exposed to radiation-induced gastrointestinal toxicity. Our results suggest that the administration of MSC-derived extracellular vesicles could be an effective therapy for limiting acute radiation syndrome.

Zonulin as a potential putative biomarker of risk for shared type 1 diabetes and celiac disease autoimmunity.

The incidence of type 1 diabetes (T1D) is increasing annually, in addition to other childhood-onset autoimmune diseases. This review is inspired by recent strides in research defining the pathophysiology of autoimmunity in celiac disease, a disease that has significant genetic overlap with T1D. Population genetic studies have demonstrated an increased proportion of newly diagnosed young children with T1D also have a higher genetic risk of celiac disease, suggesting that shared environmental risk factors are driving the incidence of both diseases. The small intestine barrier forms a tightly regulated interface of the immune system with the outside world and largely controls the mucosal immune response to non-self-antigens, dictating the balance between tolerance and immune response. Zonulin is the only known physiological modulator of the intercellular tight junctions, important in antigen trafficking, and therefore, is a key player in regulation of the mucosal immune response. While usually tightly controlled, when the zonulin pathway is dysregulated by changes in microbiome composition and function, antigen trafficking control is lost, leading to loss of mucosal tolerance in genetically susceptible individuals. The tenant of this hypothesis is that loss of tolerance would not occur if the zonulin-dependent intestinal barrier function is restored, thereby preventing the influence of environmental triggers in individuals genetically susceptible to autoimmunity. This review outlines the current research and a structured hypothesis on how a dysregulated small intestinal epithelial barrier, a "leaky gut," may be important in the pathogenesis of autoimmunity in certain individuals at risk of both T1D and celiac disease.

Clostridium perfringens type C necrotic enteritis in pigs: diagnosis, pathogenesis, and prevention.

Clostridium perfringens type C causes severe and lethal necrotic enteritis (NE) in newborn piglets. NE is diagnosed through a combination of pathology and bacteriologic investigations. The hallmark lesion of NE is deep, segmental mucosal necrosis with marked hemorrhage of the small intestine. C. perfringens can be isolated from intestinal samples in acute cases but it is more challenging to identify pathogenic strains in subacute-to-chronic cases. Toxinotyping or genotyping is required to differentiate C. perfringens type C from commensal type A strains. Recent research has extended our knowledge about the pathogenesis of the disease, although important aspects remain to be determined. The pathogenesis involves rapid overgrowth of C. perfringens type C in the small intestine, inhibition of beta-toxin (CPB) degradation by trypsin inhibitors in the colostrum of sows, and most likely initial damage to the small intestinal epithelial barrier. CPB itself acts primarily on vascular endothelial cells in the mucosa and can also inhibit platelet function. Prevention of the disease is achieved by immunization of pregnant sows with C. perfringens type C toxoid vaccines, combined with proper sanitation on farms. For the implementation of prevention strategies, it is important to differentiate between disease-free and pathogen-free status of a herd. The latter is more challenging to maintain, given that C. perfringens type C can persist for a long time in the environment and in the intestinal tract of adult animals and thus can be distributed via clinically and bacteriologically inapparent carrier animals.

Diagnosis of Celiac Disease and Environmental Enteropathy on Biopsy Images Using Color Balancing on Convolutional Neural Networks.

Celiac Disease (CD) and Environmental Enteropathy (EE) are common causes of malnutrition and adversely impact normal childhood development. CD is an autoimmune disorder that is prevalent worldwide and is caused by an increased sensitivity to gluten. Gluten exposure destructs the small intestinal epithelial barrier, resulting in nutrient mal-absorption and childhood under-nutrition. EE also results in barrier dysfunction but is thought to be caused by an increased vulnerability to infections. EE has been implicated as the predominant cause of under-nutrition, oral vaccine failure, and impaired cognitive development in low-and-middle-income countries. Both conditions require a tissue biopsy for diagnosis, and a major challenge of interpreting clinical biopsy images to differentiate between these gastrointestinal diseases is striking histopathologic overlap between them. In the current study, we propose a convolutional neural network (CNN) to classify duodenal biopsy images from subjects with CD, EE, and healthy controls. We evaluated the performance of our proposed model using a large cohort containing 1000 biopsy images. Our evaluations show that the proposed model achieves an area under ROC of 0.99, 1.00, and 0.97 for CD, EE, and healthy controls, respectively. These results demonstrate the discriminative power of the proposed model in duodenal biopsies classification.

IFN-γ, IL-17A, or zonulin rapidly increase the permeability of the blood-brain and small intestinal epithelial barriers: Relevance for neuro-inflammatory diseases.

Breakdown of the blood-brain barrier (BBB) precedes lesion formation in the brains of multiple sclerosis (MS) patients. Since recent data implicate disruption of the small intestinal epithelial barrier (IEB) in the pathogenesis of MS, we hypothesized that the increased permeability of the BBB and IEB are mechanistically linked. Zonulin, a protein produced by small intestine epithelium, can rapidly increase small intestinal permeability. Zonulin blood levels are elevated in MS, but it is unknown whether zonulin can also disrupt the BBB. Increased production of IL-17A and IFN-γ has been implicated in the pathogenesis of MS, epilepsy, and stroke, and these cytokines impact BBB integrity after 24 h. We here report that primary human brain microvascular endothelial cells expressed the EGFR and PAR2 receptors necessary to respond to zonulin, and that zonulin increased BBB permeability to a 40 kDa dextran tracer within 1 h. Moreover, both IL-17A and IFN-γ also rapidly increased BBB and IEB permeability. By using confocal microscopy, we found that exposure of the IEB to zonulin, IFN-γ, or IL-17A invitro rapidly modified the localization of the TJ proteins, ZO-1, claudin-5, and occludin. TJ disassembly was accompanied by marked depolymerization of the peri-junctional F-actin cytoskeleton. Our data indicate that IFN-γ, IL-17A, or zonulin can increase the permeability of the IEB and BBB rapidly invitro, by modifying TJs and the underlying actin cytoskeleton. These observations may help clarify how the gut-brain axis mediates the pathogenesis of neuro-inflammatory diseases.

Glucagon-Like Peptide-2 Improve Intestinal Mucosal Barrier Function in Aged Rats.

Glucagon-like peptide-2 (GLP-2) plays a major role in repairing impaired intestinal mucosa, but its mechanism in the improvement of intestinal barrier function during the aging process remains unclear. In this study, 26-month-old male Sprague-Dawley rats were randomized to control group and GLP-2 group treated with a dose of 250 μg•kg-1•d-1 by intraperitoneal injection. After 14 days of treatment, intestinal mucosal morphometric changes were observed by light microscopy and transmission electron microscopy (TEM). Small intestinal permeability was evaluated by fluorescein isothiocyanate (FITC)-labeled dextran. The mRNA and protein expression of Zonula Occludens-1 (ZO-1), occludin, claudin-1 and the GLP-2 receptor (GLP-2R) were detected by Real-time PCR and Western blot. Our results showed that GLP-2 administration significantly improved the age-related atrophy of intestinal mucosa and villi and increased small intestinal permeability. The mRNA and protein expression of ZO-1and occludin in ileum were up regulated in the GLP-2-treated old rats. In addition, the serum GLP-2 levels were negatively correlated with small intestinal permeability measured by FITC-dextran levels (r=-0.610, P<0.01). Taking all these data together, it is concluded that GLP-2 improved small intestinal epithelial barrier function in aged rats mainly by facilitating intestinal mucosa growth, alleviating the increased small intestinal permeability and increasing ZO-1 and occludin expression. Our observations provide evidence for the clinical significance of GLP-2 in preventing the intestinal epithelial barrier dysfunction during aging.

Bovine dairy complex lipids improve in vitro measures of small intestinal epithelial barrier integrity.

Appropriate intestinal barrier maturation is essential for absorbing nutrients and preventing pathogens and toxins from entering the body. Compared to breast-fed infants, formula-fed infants are more susceptible to barrier dysfunction-associated illnesses. In infant formula dairy lipids are usually replaced with plant lipids. We hypothesised that dairy complex lipids improve in vitro intestinal epithelial barrier integrity. We tested milkfat high in conjugated linoleic acid, beta serum (SureStart™Lipid100), beta serum concentrate (BSC) and a ganglioside-rich fraction (G600). Using Caco-2 cells as a model of the human small intestinal epithelium, we analysed the effects of the ingredients on trans-epithelial electrical resistance (TEER), mannitol flux, and tight junction protein co-localisation. BSC induced a dose-dependent improvement in TEER across unchallenged cell layers, maintained the co-localisation of tight junction proteins in TNFα-challenged cells with increased permeability, and mitigated the TEER-reducing effects of lipopolysaccharide (LPS). G600 also increased TEER across healthy and LPS-challenged cells, but it did not alter the co-location of tight junction proteins in TNFα-challenged cells. SureStart™Lipid100 had similar TEER-increasing effects to BSC when added at twice the concentration (similar lipid concentration). Ultimately, this research aims to contribute to the development of infant formulas supplemented with dairy complex lipids that support infant intestinal barrier maturation.

Primary human polarized small intestinal epithelial barriers respond differently to a hazardous and an innocuous protein

An experimental platform employing human derived intestinal epithelial cell (IEC) line monolayers grown on permeable Transwell® filters was previously investigated to differentiate between hazardous and innocuous proteins. This approach was effective at distinguishing these types of proteins and perturbation of monolayer integrity, particularly transepithelial electrical resistance (TEER), was the most sensitive indicator. In the current report, in vitro indicators of monolayer integrity, cytotoxicity, and inflammation were evaluated using primary (non-transformed) human polarized small intestinal epithelial barriers cultured on Transwell® filters to compare effects of a hazardous protein (Clostridium difficile Toxin A [ToxA]) and an innocuous protein (bovine serum albumin [BSA]). ToxA exerted a reproducible decrease on barrier integrity at doses comparable to those producing effects observed from cell line-derived IEC monolayers, with TEER being the most sensitive indicator. In contrast, BSA, tested at concentrations substantially higher than ToxA, did not cause changes in any of the tested variables. These results demonstrate a similarity in response to certain proteins between cell line-derived polarized IEC models and a primary human polarized small intestinal epithelial barrier model, thereby reinforcing the potential usefulness of cell line-derived polarized IECs as a valid experimental platform to differentiate between hazardous and non-hazardous proteins.

Mechanism of nonsteroidal antiinflammatory drugs-induced injury in rats small intestinal epithelial barrier and the effects of drug interfering

Objective To investigate the assessment methods and mechanisms of nonsteroidal antiinflammatory drugs （NSAID）-induced injury in rat small intestinal epithelial barrier,and to explore the protective effects of mucosal protective agents and antacids on it.Methods A total of 96 rats were evenly divided into the morphologic observation group and the mechanism research group,and 48 in each group.Then each group was evenly divided into eight subgroups：the healthy control group,the model group （model established with indomethacin）,the teprenone prevention group,the rabeprazole prevention group,the treatment control group,the teprenone treatment group,the rabeprazole treatment group and the teprenone and rabeprazole combined group （combined group）,six in each group.Exfoliated cells gap density of small intestine of each subgroup was determined by confocal laser endomicroscopy.Serum level of tumor necrosis factor-α （TNF-α）was measured with enzyme-linked immunosorbent assay （ELISA）. The expression of nuclear factor-κB （NF-κB）,caspase-3,zonula occludens-1 （ZO-1 ）and occludin at protein level was detected by Western blotting.The LSD-t test or Hamhane′s T2 test was performed for statistical analysis.Results The exfoliated cells gap densities of the teprenone prevention group and the rabeprazole prevention group were （57.43 ± 24.55 ）/1 000 and （59.80 ± 21 .14 ）/1 000,respectively, which were both lower than that of the model group （（110.93±50.58）/1 000）,and the differences were statistically significant （t= 53.50 and 54.13,both P 〈 0.01 ）.The exfoliated cells gap density of the combined group was （40.53 ±15 .39）/1 000,which was lower than that of the treatment control group （（93.80±40.65 ）/1 000 ）,and the difference was statistically significant （t =44.27,P 〈0.01 ）.The serum levels of TNF-α of the teprenone prevention group and the rabeprazole prevention group were （25 .80±8.97）ng/L and （22.74 ±7.15 ）ng/L,repsectively,which were both lower than that of the model group （（44.48 ± 7.42 ）ng/L）,and the differences were statistically significant （t = 18.68 and 21 .74,both P 〈0.01 ）.The serum level of TNF-αof the combined group （（13.66 ±4.98）ng/L）was lower than that of the treatment control group （（24.67±6.70）ng/L）,and the difference was statistically significant （t = 9.02,P 〈 0.01 ）.The caspase-3 levels of teprenone prevention group and rabeprazole prevention group were 1 .47 ±0.35 and 1 .58 ±0.34,and the NF-κB levels of these two groups were 1 .27±0.14 and 1 .21 ± 0.10,respectively.Compared with those of model group （2.44 ± 0.45 and 1 .69±0.13）,the differences were statistically significant （t =0.97,0.86,0.42 and 0.48,respectively, all P 〈0.01 ）.The levels of caspase-3 and NF-κB of the combined group were 0.66±0.06 and 0.44 ± 0.21 ,respectively,which were lower than those of the treatment control group,and the differences were statistically significant （t=0.34 and 0.56,both P 〈0.01）.The expressions of occludin at protein level of the teprenone prevention group and the rabeprazole prevention group were 0.69 ±0.16 and 0.74 ±0.11 , and the levels of ZO-1 were 0.81 ± 0.08 and 0.84 ± 0.12.Compared with those of the model group （0.45 ±0.22 and 0.64±0.07 ）,the differences were statistically significant （t =0.24,0.29,0.17 and 0.21 ,respectively,all P 〈0.01 ）.The levels of occludin and ZO-1 of the combined group were 2.50 ± 0.46 and 1 .76±0.18,which were higher than those of the treatment control group,and the differences were statistically significant （t =1 .50 and 0.76,both P 〈0.01 ）.Conclusions The exfoliated cells gap density may be a valuable indicator to predict the degree of inflammation response and permeability of epithelial barrier as well as to evaluate efficacy of medication.Teprenone and rabeprazole have prevention and treatment effects on NSAID-induced injury in rat small intestine. Key words: Microscopy, confocal; Epithelial barrier; Exfoliated cells gap density; Tumor necrosisfactor-alpha; NF-kappa B; Tight junctions protein

PTU-036 Environmental Enteropathy: Imaging The Cellular Basis Of Disrupted Barrier Function

IntroductionEnvironmental enteropathy (EE), originally termed tropical enteropathy, is very common in overcrowded living conditions in developing countries. It predisposes to growth failure in the young, and probably to poor performance...

Deoxynivalenol and E.coli lipopolysaccharide alter epithelial proliferation and spatial distribution of apical junction proteins along the small intestinal axis1

We investigated a proposed synergistic effect of deoxynivalenol (DON) and lipopolysaccharides (LPS) on small intestinal architecture and epithelial barrier integrity in pigs. Crypt depth and intestinal cell proliferation were analyzed, as well as expression of zonula occludens protein-1 (ZO-1) and β-catenin of the apical junction complex along the small intestine. Barrows (26.2±4.1 kg) were fed restrictedly either a control diet (CON) or a diet naturally contaminated with 3.1 mg DON/kg feed (DON) for 37 d. At d 37, the control group was infused for 1 h either with 100 μg/kg BW of DON (CON-DON, n=6), 7.5 μg/kg BW of LPS (CON-LPS, n=6), a combination of both (CON-DON+LPS, n=7), or 0.9% NaCl (CON-CON, n=6) and the DON group with 7.5 μg/kg BW of LPS (DON-LPS, n=8) or 0.9% NaCl (DON-CON, n=6). Pigs were euthanized 3.25 h after start of infusion. Immunohistochemistry (5'-bromo-2'-deoxyuridine for proliferation) and immunofluorescence (ZO-1 and β-catenin) from duodenum, proximal jejunum, mid-jejunum, proximal ileum, and terminal ileum were analyzed for crypt depth, cell proliferation, and apical junction proteins. Duodenal crypts were deeper compared with the other 4 intestinal regions, and proximal jejunal crypts were deeper than those of mid-jejunum and proximal ileum (P<0.001). Epithelial proliferation showed a bell-shaped distribution along the small intestinal axis. Duodenal proliferating cells had the least number compared with jejunal sections and proximal ileum (P<0.001). Neither DON nor LPS affected these variables. Zonula occludens-1 displayed a distinct spatial distribution in the epithelium with an apical and a cytosolic component. Apical expression of ZO-1 was severely damaged in the mid-jejunum (P<0.001) of CON-DON compared with animals treated with LPS. Also, in all animals receiving LPS systemically, the cytosolic ZO-1 fraction in the 3 upper gut sections disappeared completely. This effect was independent of DON presence. Control pigs had a greater basolateral β-catenin accumulation (P<0.05) in the cells, whereas the protein distribution did not differ in CON-DON pigs. In conclusion, results of this experiment demonstrated that epithelial proliferation has a distinct pattern along the small intestine and is not necessarily positively linked to crypt depth in pigs. Furthermore, results indicate that LPS changed the spatial distribution of ZO-1. A synergistic effect of DON and LPS on intestinal architecture could not be verified in the present study.

Defects in small intestinal epithelial barrier function and morphology associated with peri-weaning failure to thrive syndrome (PFTS) in swine

The objective of this study was to investigate intestinal function and morphology associated with peri-weaning failure to thrive syndrome (PFTS) in swine. Jejunum and distal ileum from control and pigs exhibiting PFTS was harvested at weaning, 4 and 11days post-weaning (PW) for intestinal barrier function studies and histological analyses (n=6 pigs per group). Marked disturbances in intestinal barrier function was observed in PFTS pigs, compared with controls, indicated by lower (p<0.05) TER and increased (p<0.01) permeability to FITC dextran (4kDa). Intestines from weaned pigs, subjected to a 4-day fast, exhibited minor disturbances in intestinal barrier function. Villus atrophy and crypt hyperplasia were observed in the PFTS intestine compared with control and fasted pigs. These data demonstrate that PFTS is associated with profound disturbances in intestinal epithelial barrier function and alterations in mucosal and epithelial morphology in which anorexia is not the sole factor.