Intestinal Barrier Function Damage Research Articles

Inhibition of miR-142-3p promotes intestinal epithelial proliferation and barrier function after ischemia/reperfusion injury by targeting FoxM1.

Damage of intestinal barrier function (BF) after ischemia/reperfusion (I/R) injury can induce serious complications and high mortality. MicroRNAs (miRNAs) are involved in intestinal mucosal BF and epithelial proliferation after I/R injury have been reported. We aimed to investigate the role and regulatory mechanism of miR-142-3p (miR-142) in intestinal epithelial proliferation and BF after I/R injury. We detected the proliferation, barrier function and miR-142 expression in clinical ischemic intestinal tissues. Furthermore, we induced an in vivo intestinal I/R injury mouse model and in vitro IEC-6 cells hypoxia/reoxygenation (H/R) injury model. After increasing and decreasing expression of miR-142, we detected the proliferation and barrier function of intestinal epithelial cells after I/R or H/R injury. We found that miR-142 expression was significantly increased in clinical ischemic intestinal mucosa and mouse intestinal mucosa exposed to I/R injury, and there was an inverse relationship between miR-142 and proliferation/BF. Inhibition of miR-142 significant promoted intestinal epithelial proliferation and BF after I/R injury. Furthermore, inhibition of miR-142 improved overall survival rate of mice after I/R injury. MiR-142 directly targeted FoxM1 which was identified by bioinformatics analysis and luciferase activity assay in IEC-6 cells. Inhibition of miR-142 promotes intestinal epithelial proliferation and BF after I/R injury in a FoxM1-mediated manner.

The protective effects of Bacillus licheniformis against inflammatory responses and intestinal barrier damage in broilers with necrotic enteritis induced by Clostridium perfringens.

Bacillus licheniformis is a gram-positive bacterium that has strong environmental adaptability and can improve the growth performance, immunity, and antioxidant function of broilers. The current study aimed to elucidate the protective capability of B. licheniformis against inflammatory responses and intestinal barrier damage in broilers with necrotic enteritis (NE) induced by Clostridium perfringens (CP). The results showed that B. licheniformis enhanced the final body weight in broilers compared with that of broilers in the CP group after the stress of infection (P < 0.05). Bacillus licheniformis reversed the decreased levels of serum and jejunum mucosa immunoglobulins and anti-inflammatory cytokines, reduced the values of villus height and the ratio of villus height to crypt depth, and mitigated the increased levels of serum d-lactic acid and diamine oxidase in CP-challenged broilers (P < 0.05). Moreover, B. licheniformis modulated the expression levels of genes involved in the TLR4/NF-κB signalling pathway, the NLRP3 inflammasome activation pathway, and the sirt 1/Parkin signalling pathway in CP-challenged broilers. Compared with the CP challenge group, the B. licheniformis-treated group exhibited reduced abundance values of Shuttleworthia and Alistipes and enhanced abundance values of Parabacteroides in the caecal contents (P < 0.05). Bacillus licheniformis improved the final body weight and alleviated the inflammatory response and intestinal barrier function damage in birds with NE induced by CP by maintaining intestinal physiological function, enhancing immunity, regulating inflammatory cytokine secretion, modulating the mitophagy response, and increasing the abundance of beneficial intestinal flora. © 2023 Society of Chemical Industry.

The protective effect of Ganoderma atrum polysaccharide on intestinal barrier function damage induced by acrylamide in mice through TLR4/MyD88/NF-κB based on the iTRAQ analysis.

The potential mechanism for the protective effect of Ganoderma atrum (G. atrum) polysaccharide (PSG-1) on acrylamide (AA) induced intestinal damage in mice was explored. Results showed that PSG-1 pretreatment prevented AA-induced injury by decreasing intestinal permeability and serum D-lactate acid (D-Lac) levels and increasing the number of small intestinal goblet cells and IgA secreting cells. In addition, PSG-1 pretreatment effectively reduced malondialdehyde (MDA) level and raised superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) activities in the intestine. Furthermore, PSG-1 administration decreased the levels of pro-inflammatory factors including IL-1β, TNF-α, and IL-6, while the anti-inflammatory factor IL-10 was elevated. Meanwhile, PSG-1 could increase the performance of tight junction (TJ) proteins such as Occludin, Claudin-1 and ZO-1. Moreover, according to the isobaric tag for relative and absolute quantitation (iTRAQ) and Western blot results, PSG-1 could reduce AA-induced intestinal injury through TLR4/MyD88/NF-κB signaling pathway. Overall, the present study suggested that PSG-1 protected intestinal permeability and barrier function in mice via reducing inflammation and oxidative stress, and effectively prevented AA-induced intestinal injury in mice.

Biogenic Selenium Nanoparticles Synthesized by Lactobacillus casei ATCC 393 Alleviate Acute Hypobaric Hypoxia-Induced Intestinal Barrier Dysfunction in C57BL/6 Mice.

Exposure to hypobaric hypoxia at high altitude will cause different tissue and organ damage over a long period of time. Studies have shown that hypobaric hypoxia can cause severe primary intestinal barrier dysfunction, and then cause multiple organ dysfunction. Our previous research showed that selenium nanoparticles (SeNPs) synthesized by Lactobacillus casei ATCC 393 (L. casei ATCC 393) can effectively alleviate intestinal barrier dysfunction caused by oxidative stress and inflammationin mice. This study was conducted to investigate the protective effect of biological SeNPs synthesized by L. casei ATCC 393 on intestinal barrier function in acute hypobaric hypoxic stress mice. The results showed that compared with the hypobaric hypoxic, the SeNPs synthesized by L. casei ATCC 393 by oral administration could effectively alleviate the shortening of intestinal villi, which decreased the level of diamine oxidase (DAO) and myeloperoxidase (MPO), and the expression level of tight junction protein in ileum was increased. In addition, SeNPs significantly increased the activities of superoxide dismutase (SOD), cyclooxygenase (COX-1) and glutathione peroxidase (GPx), and decreased the level of malondialdehyde (MDA), and inhibit the increase of hypoxia related factor. SeNPs effectively regulate the intestinal microecology disorder caused by hypobaric hypoxia stress, and maintain the intestinal microecology balance. In addition, oral administration of SeNPs had better protective effect on intestinal barrier function of mice under hypobaric hypoxia stress. These results suggested that SeNPs synthesized by L. casei ATCC 393 can effectively alleviate the damage of intestinal barrier function under acute hypobaric hypoxic stress, which may be closely related to the antioxidant activity of SeNPs.

Mechanisms and prevention of intestinal barrier function damage in traumatic hemorrhagic shock

Mechanisms and prevention of intestinal barrier function damage in traumatic hemorrhagic shock

Fenofibrate Ameliorated Systemic and Retinal Inflammation and Modulated Gut Microbiota in High-Fat Diet-Induced Mice.

Fenofibrate, as a lipid-lowering drug, has been reported to have a protective effect on the retina independent with plasma lipid levels. This study aimed to investigate that the ameliorative effects of fenofibrate on systemic and retinal inflammation, as well as gut microbiota dysbiosis in high-fat diet (HFD)-induced mice. C57BL/6J mice were randomly allocated into four groups: standard diet (SD) group; HFD group; SD plus fenofibrate (SD_ Fe) group; HFD plus fenofibrate (HFD_ Fe) group. After successfully establishing models (5 months), indicators associated with lipid, gut barrier, inflammation and gut microbiota were investigated. Our results showed that supplementing the HFD with fenofibrate decreased body weight gain, alleviated dyslipidemia and reversed the downregulation of short-chain fatty acid (SCFAs) in serum, retina and feces. Fenofibrate ameliorated intestinal barrier function damage in HFD-induced mice. Fenofibrate coadministration inhibited the levels of inflammatory factor and lipopolysaccharide (LPS) in the serum and attenuated inflammatory response in the retina of HFD-induced mice. Systemic LPS was positively correlated with a series of inflammatory factors in serum and retina, respectively. Fenofibrate supplementation down-regulated the abundances of LPS-associated bacteria in HFD mice, including Firmicutes and Proteobacteria at the phylum level, Desulfovibrionaceae at the family level, as well as unclassified_ Desulfovibrionaceae, Acetatifactor, Flavonifractor, Oscillibacter and Anaerotruncus at the genus level. However, fenofibrate treatment up-regulated the abundances of SCFA-associated bacteria in HFD mice, including Bacteroidetes at the phylum level, Porphyromonadaceae at the family level, as well as unclassified_Porphyromonadaceae, Barnesiella, Alloprevotella and Bifidobacterium at the genus level. In conclusion, our results confirmed fenofibrate could attenuate HFD-induced systemic and retinal inflammation, accompanying with restoration of intestinal barrier damage and modulation of gut microbiota/metabolites. This work provided an explanation for the ameliorative effects of fenofibrate on HFD-induced systemic and retinal inflammation might be partially related with the modulation of gut microbiota and its metabolites.

Disordered Expression of Tight Junction Proteins Is Involved in the Mo-induced Intestinal Microenvironment Dysbiosis in Sheep.

To evaluate the molybdenum (Mo)-induced changes of intestinal morphology and the relationship of intestinal tight junction (TJ) proteins expression and intestinal barrier function, a total of 20 healthy sheep were randomly divided into five groups of four: 0, 5, 10, 20, and 50mg/kg BW/day Na2MoO4·2H2O were administrated in five groups named control group, Mo 5 group, Mo 10 group, Mo 20 group, and Mo 50 group, respectively. After 28days of Mo treatment, the duodenum, the jejunum, and the ileum tissue were collected. The histopathology and the developmental parameters were evaluated by hematoxylin-eosin staining. The intestinal epithelial cell DNA damage was detected by TdT-mediated dUTP nick end labeling assay. The intestinal glycoprotein and the goblet cells were analyzed by Alcian Blue-Periodic Acid-Schiff (AB-PAS) staining and PAS staining, respectively. TJ proteins were determined by immunofluorescence technology. Results showed that excessive Mo significantly decreased the small intestinal villus height (VH), crypt depth (CD), VH/CD, and mucosal thickness (P < 0.05 or P < 0.01) while induced the damage of DNA in small intestinal epithelial cells. Moreover, excessive Mo injured intestinal barrier function by decreasing the percent of glycoprotein distribution area (P < 0.05) and the relative density of intestinal goblet cells (P < 0.05). Mo treatment induced decreased (P < 0.01) expression of Zonula Occludens-1, Occludin, and Claudin-1. In conclusion, excessive Mo interfered with the expression of TJ proteins, inhibited intestinal epithelial development, and further aggravated the intestinal barrier function damage, leading to disturbing the small intestinal microenvironment balance.

Roxadustat Attenuates the Disruption of Epithelial Tight Junction in Caco2 Cells and a Rat Model of CKD Through MicroRNA-223.

IntroductionIncreasing evidence supports the idea that the disruption of epithelial tight junction proteins (TJPs) caused by accumulation of uremia toxins, such as homocysteine (Hcy), is one of the most important mechanisms underlying the damage of intestinal barrier function (IBF) in chronic kidney disease (CKD). Since the decrease of hypoxia inducible factor-1α (HIF-1α) is reported to be involved in Hcy-induced cell injury, and the upregulation of microRNA-223 (miR-223) plays a vital protective role in the impairment of IBF in the experimental colitis, we investigated the effect of HIF-1α stabilizer roxadustat on the disruption of TJPs induced by Hcy and CKD and the underlying mechanism.MethodsChronic kidney disease was induced in rats via 5/6 nephrectomy. In a series of experiments, the rats were treated orally with roxadustat of different doses. The expression of tight junction proteins, HIF-1α, and miR-223 was analyzed in different groups by western blotting analysis, RT-qPCR techniques and immunofluorescence. A series of experiments with cultured Caco2 cells was performed.ResultsThe results showed that the expression of TJPs (occludin, claudin-1, and ZO-1) decreased significantly, accompanied by the reduction of HIF-1α and miR-223 in Hcy-treated Caco2 cells and colonic mucosa of uremic rats. The reduction of HIF-1α and miR-223 was reversed by roxadustat and the decrease of TJPs expression was attenuated in both Caco2 cells induced by Hcy and colon tissue of CKD rats. Furthermore, transfection with miR-223 mimics increased the expression of TJPs, while transfection with miR-223 inhibitor decreased their expression in Caco2 cells. MiR-223 inhibitor applied before roxadustat treatment partly diminished the effect of roxadustat on TJPs expression in Caco2 cells.ConclusionThese results indicated that roxadustat attenuated the disruption of epithelial TJPs induced by Hcy in Caco2 cells and the damage of colonic epithelium in CKD rats through the upregulation of miR-223 induced by HIF-1α. A novel insight into the IBF dysfunction in CKD was provided, and it suggests a potential therapeutic use of roxadustat for the IBF dysfunction besides anemia in CKD.

Egg white ovomucin hydrolysate inhibits intestinal integrity damage in LPS-treated Caco-2 cells

Disruption of the intestinal barrier is closely associated with intestinal inflammation and disease development. Ovomucin is a bioactive protein in chicken egg white, and its hydrolysate has been revealed to prevent the adhesion of pathogen to intestinal epithelial cells. However, the effect of ovomucin hydrolysate on intestinal barrier integrity and associated anti-inflammation mechanism has not been demonstrated. Here, we investigated its activity in lipopolysaccharide (LPS)-induced monolayer dysfunction of differentiated Caco-2 cells to unravel the underlying molecular mechanisms. Ovomucin-protex 26L hydrolysate significantly increased transepithelial electronic resistance (TEER) values, decreased the paracellular FITC-dextran flux permeability, and recovered the expression of occludin and ZO-1 in LPS-stimulated Caco-2 cells. Meanwhile, ovomucin-protex 26L hydrolysate significantly inhibited the LPS-induced activation of NF-κB and MAPK pathways. These results suggested the ability of ovomucin-protex 26L hydrolysate to suppress LPS-induced intestinal barrier function damage via the inhibition of inflammatory responses.

Lactobacillus coryniformis MXJ32 administration ameliorates azoxymethane/dextran sulfate sodium-induced colitis-associated colorectal cancer via reshaping intestinal microenvironment and alleviating inflammatory response.

Gut microbiota has been reported to contribute to either prevent or promote colorectal cancer (CRC), and treatment with probiotics might be a promising intervention method. The present study aimed to evaluate the potential anti-CRC effects of Lactobacillus coryniformis MXJ32 on a colitis-associated (CA)-CRC mouse model. The CA-CRC mouse model was induced by a single intraperitoneal injection of 10mg/kg azoxymethane and followed by three 7-day cycles of 2% dextran sulfate sodium in drinking water with a 14-day recovery period. Mice were supplemented with L. coryniformis MXJ32 by oral gavage (1 × 109CFU/day/mouse). The CA-CRC attenuating effects of this probiotic were assessed via intestinal barrier integrity, inflammation, and gut microenvironment. Treatment with L. coryniformis MXJ32 could significantly inhibit the total number of tumors and the average tumor diameter. This probiotic administration prevented the damage of intestinal barrier function by enhancing the expression of tight junction proteins (Occludin, Claudin-1, and ZO-1) and recovering the loss of goblet cells. Moreover, L. coryniformis MXJ32 alleviated intestinal inflammation via down-regulating the expression of inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-γ, and IL-17a) and chemokines (Cxcl1, Cxcl2, Cxcl3, Cxcl5, and Ccl7). In addition, L. coryniformis MXJ32 supplementation increased the abundance of some beneficial bacteria (such as SCFAs-producing bacteria, Lactobacillus, Bifidobacterium, Akkermansia, and Faecalibaculum) and decreased the abundance of some harmful bacteria (such as pro-inflammatory bacteria, Desulfovibrio and Helicobacter), which in turn attenuated the overexpression of inflammation. Lactobacillus coryniformis MXJ32 could effectively ameliorate CA-CRC via regulating intestinal microenvironment, alleviating inflammation, and intestinal barrier damage, which further suggested that L. coryniformis MXJ32 could be considered as a functional food ingredient for the alleviation of CA-CRC.

Dietary Fiber Ameliorates Lipopolysaccharide-Induced Intestinal Barrier Function Damage in Piglets by Modulation of Intestinal Microbiome.

ABSTRACTWeaning of piglets is accompanied by intestinal inflammation, impaired intestinal barrier function, and intestinal microflora disorder. Regulating intestinal microflora structure can directly or indirectly affect intestinal health and host growth and development. However, whether dietary fiber (DF) affects the inflammatory response and barrier function by affecting the intestinal microflora and its metabolites is unclear. In this study, we investigated the role of intestinal microflora in relieving immune stress and maintaining homeostasis using piglets with lipopolysaccharide (LPS)-induced intestinal injury as a model. DF improved intestinal morphology and barrier function, inhibited the expression of inflammatory signal pathways (Toll-like receptor 2 [TLR2], TLR4, and NF-κB) and proinflammatory cytokines (interleukin 1β [IL-1β], IL-6, and tumor necrosis factor alpha [TNF-α]), and upregulated the expression of barrier-related genes (encoding claudin-1, occludin, and ZO-1). The contents of proinflammatory cytokines (IL-1β, IL-6, and TNF-α) and the activity of diamine oxidase in plasma were decreased. Meanwhile, DF had a strong effect on the composition and function of intestinal microflora at different taxonomic levels, the relative abundances of cellulolytic bacteria and anti-inflammatory bacteria were increased, and the concentrations of propionate, butyrate, and total short-chain fatty acids (SCFAs) in intestinal contents were increased. In addition, the correlation analysis also revealed the potential relationship between metabolites and certain intestinal microflora, as well as the relationship between metabolites and intestinal morphology, intestinal gene expression, and plasma cytokine levels. These results indicate that DF improves intestinal barrier function, in part, by altering intestinal microbiota composition and increasing the synthesis of SCFAs, which subsequently alleviate local and systemic inflammation.IMPORTANCE Adding DF to the diet of LPS-challenged piglets alleviated intestinal and systemic inflammation, improved intestinal barrier function, and ultimately alleviated the growth retardation of piglets. In addition, the addition of DF significantly increased the relative abundance of SCFA-producing bacteria and the production of SCFAs. We believe that the improvement of growth performance of piglets with LPS-induced injury can be attributed to the beneficial effects of DF on intestinal microflora and SCFAs, which reduced the inflammatory response in piglets, improving intestinal barrier function and enhancing body health. These research results provide a theoretical basis and guidance for the use of specific fiber sources in the diet to improve intestinal health and growth performance of piglets and thus alleviate weaning stress. Our data also provide insights for studying the role of DF in regulating gastrointestinal function in human infants.

Fermentation Production of Ganoderma lucidum by Bacillus subtilis Ameliorated Ceftriaxone-induced Intestinal Dysbiosis and Improved Intestinal Mucosal Barrier Function in Mice

ObjectiveThis study aimed to develop a type of Ganoderma lucidum (G. lucidum)-probiotic fermentation broth that can effectively improve the intestinal mucosal barrier function of mice with ceftriaxone-induced intestinal dysbiosis. MethodsBy means of absorbance of optical density (OD) value and phenol-concentrated sulfuric acid measurement of polysaccharide content, the probiotic species can grow on the medium of G. lucidum were screened out, and the concentration of the medium of G. lucidum was determined, and the fermentation broth was prepared for subsequent experiments. Thirty-two SPF grade male BALB/c mice were randomly divided into four groups (eight mice in each group), namely control group (CON), intestinal mucosal barrier damage model group (CS), fermentation broth intervention group (FT) and G. lucidum medium intervention group (GL), respectively. The intestinal dysregulation model was induced by intra-gastric administration of 0.2 mL ceftriaxone sodium (twice a day for seven consecutive days). From day 8, the FT group and GL group were gavage with 0.2 mL fermentation broth and G. lucidum medium, respectively. On day 15, all mice were sacrificed. To draw the weight curve and measure the cecal index; pathological examination of colon tissues with HE staining; serum levels of LPS, IL-10, TNF and IL-6 were detected by ELISA. Flow cytometry was used to analyze the changes of CD3 + T cells, CD4 + T cells, CD8 + T cells and macro- phages in spleen. 16S rRNA sequencing was performed to detect the intestinal microbiota structure of mice. ResultsBacillus subtilis can decompose and utilize G. lucidum fruiting body medium, and the suitable concentration of G. lucidum fruiting body medium is 33.2 mg/mL. The effect of Bacillus subtilis-G. lucidum fermentation broth on the damage of intestinal mucosal barrier caused by ceftriaxone sodium was reduced, the body weight of mice recovered and colon swellingimproved, colon histopathological injury was alleviated, inflammatory cell infiltration was alleviated, serum IL-10 increased significantly, LPS 、 TNF-α and IL-6 decreased significantly compared with model group, and the proportion of T cells and intestinal dysbiosis was improved. ConclusionsThe experimental results suggest that Bacillus subtilis-G. lucidum fermentation broth can effectively improve the intestinal barrier function damage, immune dysfunction and intestinal dysbiosis caused by antibiotic overdose, and has a certain regulatory effect on intestinal mucosal barrier function.

Radiotherapy Induces Intestinal Barrier Dysfunction by Inhibiting Autophagy.

Radiation enteritis is a common complication of abdominal irradiation (IR) therapy. However, the molecular mechanism of radiation enteritis accompanied by impaired intestinal barrier function is not clear. The aim of this study was to investigate the important role of autophagy in radiation-induced intestinal barrier function impairment. IR increased the abundance of autophagy-related genes in the colonic mucosa of mice. An autophagy activator (rapamycin) inhibited the oxidative stress (reactive oxygen species, reactive nitrogen species, malondialdehyde, and hydrogen peroxide) and inflammatory response (interleukin-1β, -6, -8, and tumor necrosis factor-α) in the colon samples. Antioxidant indices (superoxide dismutase, glutathione peroxidase, catalase, and total antioxidant capacity) in serum and colonic mucosa were significantly increased in the rapamycin group. Rapamycin can improve the activity of mitochondrial respiratory chain complexes I–V in colon mucosa. In addition, rapamycin reduced the gene expression and enzyme activity of caspase in the colonic mucosa. Levels of endotoxin, diamine peroxidase, d-lactic acid, and zonulin in serum and colonic mucosa were significantly reduced in the rapamycin group. Moreover, rapamycin significantly elevated the gene abundance of zonula occludens-1, occludin, claudin-1, and claudin-4. In contrast, completely opposite results were obtained for the autophagy inhibitor 3-methyladenine as compared to those of rapamycin. These results revealed that inhibition of autophagy is an important mechanism of intestinal barrier function damage caused by radiation. Collectively, these findings increase our understanding of the pathogenesis of radiation-induced intestinal barrier dysfunction.

Influence of dietary fiber on chronic kidney disease： Base on the gut-kidney axis theory.

Chronic kidney disease (CKD) can result in alteration of intestinal flora and damage of intestinal barrier function. Intestinal dysbios is contributes to the generation of colon-derived uremic solutes and the translocation of bacteria and endotoxins from gut lumen into the bloodstream, subsequently increasing uremic toxicity and triggering systemic inflammation, which is related to CKD progression and many complications. Studies have revealed that dietary fiber can reduce uremic toxin levels and systemic inflammation in CKD through targeting the "gut-kidney axis". Dietary fiber seems to be a promising measure for CKD treatment.

Lactobacillus frumenti Facilitates Intestinal Epithelial Barrier Function Maintenance in Early-Weaned Piglets.

Increased intestinal epithelial barrier function damages caused by early weaning stress have adverse effects on swine health and feed utilization efficiency. Probiotics have emerged as the promising antibiotic alternatives used for intestinal barrier function damage prevention. Our previous data showed that Lactobacillus frumenti was identified as a predominant Lactobacillus in the intestinal microbiota of weaned piglets. However, whether the intestinal epithelial barrier function in piglets was regulated by L. frumenti is still unclear. Here, piglets received a PBS vehicle or PBS suspension (2 ml, 108 CFU/ml) containing the L. frumenti by oral gavage once a day during the period of 6–20 days of age prior to early weaning. Our data demonstrated that oral administration of L. frumenti significantly improved the intestinal mucosal integrity and decreased the serum endotoxin and D-lactic acid levels in early-weaned piglets (26 days of age). The intestinal tight junction proteins (including ZO-1, Occludin, and Claudin-1) were significantly up-regulated by L. frumenti administration. The serum immunoglobulin G (IgG) levels, intestinal secretory immunoglobulin A (sIgA) levels, and interferon-γ (IFN-γ) levels were significantly increased by L. frumenti administration. Furthermore, our data revealed that oral administration of L. frumenti significantly increased the relative abundances of health-promoting microbes (including L. frumenti, Lactobacillus gasseri LA39, Parabacteroides distasonis, and Kazachstania telluris) and decreased the relative abundances of opportunistic pathogens (including Desulfovibrio desulfuricans and Candida humilis). Functional alteration of the intestinal bacterial community by L. frumenti administration was characterized by the significantly increased fatty acids and protein metabolism and decreased diseases-associated metabolic pathways. These findings suggest that L. frumenti facilitates intestinal epithelial barrier function maintenance in early-weaned piglets and may be a promising antibiotic alternative used for intestinal epithelial barrier function damage prevention in mammals.

Asparagine preserves intestinal barrier function from LPS-induced injury and regulates CRF/CRFR signaling pathway.

Stress causes intestinal inflammation and barrier dysfunction. Corticotrophin-releasing factor (CRF)/CRF receptor (CRFR) signaling pathway has been shown to be important for stress-induced intestinal mucosal alteration. L-Asparagine (ASN) is a powerful stimulator of ornithine decarboxylase and cell proliferation in a variety of cell types, including colonic cells. In the present study, we investigated whether dietary ASN supplementation could alleviate the damage of intestinal barrier function caused by LPS through modulation of CRF/CRFR signaling pathway. Twenty-four weaned pigs were randomly divided into one of four treatments: (1) non-challenged control; (2) Escherichia coli LPS challenged control; (3) LPS + 0.5% ASN; (4) LPS + 1.0% ASN. LPS stress induced villous atrophy, intestinal morphology disruption and decreased claudin-1 expression. ASN supplementation increased intestinal claudin-1 protein expression and alleviated villous atrophy and intestinal morphology impairment caused by LPS stress. In addition, ASN supplementation increased the number of intestinal intraepithelial lymphocytes and reversed the elevations of intestinal mast cell number and neutrophil number induced by LPS stress. Moreover, ASN decreased the mRNA expression of intestinal CRF, glucocorticoid receptors and tryptase. These results indicate that ASN attenuates intestinal barrier dysfunction induced by LPS stress, and regulates CRF/CRFR1 signaling pathway and mast cell activation.

Goat milk with and without increased concentrations of lysozyme improves repair of intestinal cell damage induced by enteroaggregative Escherichia coli

BackgroundEnteroaggregative Escherichia coli (EAEC) causes diarrhea, malnutrition and poor growth in children. Human breast milk decreases disease-causing bacteria by supplying nutrients and antimicrobial factors such as lysozyme. Goat milk with and without human lysozyme (HLZ) may improve the repair of intestinal barrier function damage induced by EAEC. This work investigates the effect of the milks on intestinal barrier function repair, bacterial adherence in Caco-2 and HEp-2 cells, intestinal cell proliferation, migration, viability and apoptosis in IEC-6 cells in the absence or presence of EAEC.MethodsRat intestinal epithelial cells (IEC-6, ATCC, Rockville, MD) were used for proliferation, migration and viability assays and human colon adenocarcinoma (Caco-2, ATCC, Rockville, MD) and human larynx carcinoma (HEp-2, ATCC, Rockville, MD) cells were used for bacterial adhesion assays. Goats expressing HLZ in their milk were generated and express HLZ in milk at concentration of 270 μg/ml . Cells were incubated with pasteurized milk from either transgenic goats expressing HLZ or non-transgenic control goats in the presence and absence of EAEC strain 042 (O44:H18).ResultsCellular proliferation was significantly greater in the presence of both HLZ transgenic and control goat milk compared to cells with no milk. Cellular migration was significantly decreased in the presence of EAEC alone but was restored in the presence of milk. Milk from HLZ transgenic goats had significantly more migration compared to control milk. Both milks significantly reduced EAEC adhesion to Caco-2 cells and transgenic milk resulted in less colonization than control milk using a HEp-2 assay. Both milks had significantly increased cellular viability as well as less apoptosis in both the absence and presence of EAEC.ConclusionsThese data demonstrated that goat milk is able to repair intestinal barrier function damage induced by EAEC and that goat milk with a higher concentration of lysozyme offers additional protection.

Intestinal barrier damage caused by trauma and lipopolysaccharide.

To investigate the intestinal barrier function damage induced by trauma and infection in rats. Experimental models of surgical trauma and infection were established in rats. Adult Sprague-Dawley rats were divided into 4 groups: control group (n = 8), EN group (n = 10), PN group (n = 9) and Sep group (n = 8). The rats in PN and Sep groups were made into PN models that received isonitrogenous, isocaloric and isovolumic TPN solution during the 7-d period. Rats in EN and Sep groups received laparotomy and cervical catheterization on day 1 and received lipopolysaccharide injection intraperitoneally on d 7. On the 7(th) day all the animals were gavaged with lactulose and mannitol to test the intestinal permeability. Twenty-four hours later samples were collected and examined. The inflammatory responses became gradually aggravated from EN group to Sep group. The mucosal structure of small intestine was markedly impaired in PN and Sep groups. There was a low response in IgA level in Sep group when compared with that of EN group. Lipopolysaccharide injection also increased the nitric oxide levels in the plasma of the rats. The intestinal permeability and bacterial translocation increased significantly in Sep group compared with that of control group. One wk of parenteral nutrition causes an atrophy of the intestinal mucosa and results in a moderate inflammatory reaction in the rats. Endotoxemia aggravates the inflammatory responses that caused by laparotomy plus TPN, increases the production of nitric oxide in the body, and damages the intestinal barrier function.

Preventive effect of glutamine on intestinal barrier dysfunction induced by severe trauma.

To investigate the mechanism underlying intestinal barrier function damage after severe trauma and the therapeutic effect of glutamine. Burned patients, and animal models of severe trauma replicated by hemorrhagic shock combined with endotoxin infusion and burn injury, were included in a serial experiment. Effects of oral glutamine on intestinal barrier function were observed in scalded rats. Parameters measured in these experiments were as follows: plasma levels of diamine oxidase (DAO), tumor necrosis factor (TNFalpha), endotoxin (LPS), and lactate as well as D-lactate by biochemical methods, lactose/mannitol (L/M) ratio in urine by SP-3400, and pathological examination of intestinal mucosa under light microscopy. Plasma DAO activity was significantly increased after injury. There was a negative correlation between plasma DAO and intestinal mucosal DAO or pHi (r=-0.93, plasma 0.80+/-0.93,2.83+/-1.71, 1.14+/-0.64,2.36+/-2.06 and 2.49+/-1.67 vs intestinal 0.52+/-0.12,0.34+/-0.03,0.45+/-0.18,0.37+/-0.26 and 0.41+/-0.07 r=-0.533, plasma 0.87+/-0.75, 1.89+/-1.13,1.21+/-0.23,3.03+/-2.61 and 4.70+/-1.22 vs pHi 7.03+/-0.05,7.05+/-0.06,7.14+/-0.096, 7.20+/-0.08 and 7.05+/-0.07 P<0.01-0.05). Positive correlations were found between DAO activity and plasma TNFalpha, LPS, lactate, L/M and D-lactate (r=0.817, 0.842, 0.872, and 0.951 plasma DAO 0.87+/-0.75,1.89+/-1.13,1.21+/-0.23,3.03+/-2.61 and 4.70+/-1.22 vs TNF 0.08+/-0.02,0.03+/-0.25, 0.17+/-0.09,0.34+/-0.15 and 0.33+/-0.18 vs LPS 0.14+/-0.03,0.16+/-0.04,0.21+/-0.02,0.18+/-0.16 and 0.37+/-0.10 vs lactate 9.03+/-2.19,18.30+/-2.56, 9.81+/-2.83,12.01+/-6.83,12.01+/-6.84 and 43.61+/-11.27 vs L/M 0.03+/-0.01,0.41+/-0.27,0.62+/-0.20, 1.70+/-0.60 r=0.774, plasma DAO 1.25+/-0.41 2.17+/-0.71 2.29+/-0.87 1.23+/-0.55 and 1.11+/-0.47 vs D-lactate 8.37+/-2.48,18.25+/-6.18, 13.96+/-4.94,8.93+/-3.00 and 12.39+/-4.94 all P<0.01), respectively. Damage of intestinal mucosa was found by pathological examination. Intestinal barrier function was improved to a certain extent by oral glutamine in scalded rats. Intestinal barrier function was damaged in the early stage after trauma. Plasma DAO activity, D-lactate content, intestinal pHi and urine L/M may be sensitive markers of intestinal mechanical injury, and glutamine may protect against intestinal barrier dysfunction after severe trauma.