Alkaline sphingomyelinase deficiency impairs intestinal mucosal barrier integrity and reduces antioxidant capacity in dextran sulfate sodium-induced colitis

BACKGROUND Ulcerative colitis is a chronic inflammatory disease of the colon with an unknown etiology.Alkaline sphingomyelinase(alk-SMase)is specifically expressed by intestinal epithelial cells,and has been reported to play an anti-inflammatory role.However,the underlying mechanism is still unclear.AIM To explore the mechanism of alk-SMase anti-inflammatory effects on intestinal barrier function and oxidative stress in dextran sulfate sodium(DSS)-induced colitis.METHODS Mice were administered 3%DSS drinking water,and disease activity index was determined to evaluate the status of colitis.Intestinal permeability was evaluated by gavage administration of fluorescein isothiocyanate dextran,and bacterial translocation was evaluated by measuring serum lipopolysaccharide.Intestinal epithelial cell ultrastructure was observed by electron microscopy.Western blotting and quantitative real-time reverse transcription-polymerase chain reaction were used to detect the expression of intestinal barrier proteins and mRNA,respectively.Serum oxidant and antioxidant marker levels were analyzed using commercial kits to assess oxidative stress levels.RESULTS Compared to wild-type(WT)mice,inflammation and intestinal permeability in alk-SMase knockout(KO)mice were more severe beginning 4 d after DSS induction.The mRNA and protein levels of intestinal barrier proteins,including zonula occludens-1,occludin,claudin-3,claudin-5,claudin-8,mucin 2,and secretory immunoglobulin A,were significantly reduced on 4 d after DSS treatment.Ultrastructural observations revealed progressive damage to the tight junctions of intestinal epithelial cells.Furthermore,by day 4,mitochondria appeared swollen and degenerated.Additionally,compared to WT mice,serum malondialdehyde levels in KO mice were higher,and the antioxidant capacity was significantly lower.The expression of the transcription factor nuclear factor erythroid 2-related factor 2(Nrf2)in the colonic mucosal tissue of KO mice was significantly decreased after DSS treatment.mRNA levels of Nrf2-regulated downstream antioxidant enzymes were also decreased.Finally,colitis in KO mice could be effectively relieved by the injection of tertiary butylhydroquinone,which is an Nrf2 activator.CONCLUSION Alk-SMase regulates the stability of the intestinal mucosal barrier and enhances antioxidant activity through the Nrf2 signaling pathway.

Dietary supplementation of bilberry anthocyanin on growth performance,intestinal mucosal barrier and cecal microbes of chickens challenged with Salmonella Typhimurium

Background Anthocyanins(AC)showed positive effects on improving the intestinal health and alleviating intestinal pathogen infections,therefore,an experiment was conducted to explore the protective effects of supplemented AC on Salmonella-infected chickens.Methods A total of 240 hatchling chickens were randomly allocated to 4 treatments,each with 6 replicates.Birds were fed a basal diet supplemented with 0(CON,and ST),100(ACL)and 400(ACH)mg/kg of AC for d 60,and orally challenged with PBS(CON)or 10^(9) CFU/bird(ST,ACL,ACH)Salmonella Typhimurium at d 14 and 16.Results(1)Compared with birds in ST,AC supplementation increased the body weight(BW)at d 18 and the average daily gain(ADG)from d 1 to 18 of the Salmonella-infected chickens(P<0.05);(2)AC decreased the number of Salmonella cells in the liver and spleen,the contents of NO in plasma and inflammatory cytokines in ileal mucosa of Salmonella-infected chickens(P<0.05);(3)Salmonella infection decreased the ileal villi height,villi height to crypt depth(V/C),and the expression of zonulaoccludins-1(ZO-1),claudin-1,occludin,and mucin 2(MUC2)in ileal mucosa.AC supplementation relieved these adverse effects,and decreased ileal crypt depth(P<0.05);(4)In cecal microbiota of Salmonella-infected chickens,AC increased(P<0.05)the alpha-diversity(Chao1,Pd,Shannon and Sobs indexes)and the relative abundance of Firmicutes,and decreased(P<0.05)the relative abundance of Proteobacteria and Bacteroidota and the enrichment of drug antimicrobial resistance,infectious bacterial disease,and immune disease pathways.Conclusions Dietary AC protected chicken against Salmonella infection via inhibiting the Salmonella colonization in liver and spleen,suppressing secretion of inflammatory cytokines,up-regulating the expression of ileal barrier-related genes,and ameliorating the composition and function of cecal microbes.Under conditions here used,100 mg/kg bilberry anthocyanin was recommended.

Puerarin alleviates sleep disorders in aged mice related to repairing intestinal mucosal barrier

More and more evidence suggests that puerarin,a potential remedy for gut inflammation,may have an ameliorative effect on sleep disturbances.However,the relationship between puerarin and sleep disruption has not been extensively researched.This study aims to explore the role and mechanisms of puerarin in improving sleep disorders.We established a light-induced sleep disorder model in mice and assessed the effects of puerarin on cognitive behavior using open field and water maze tests.Pathological detection demonstrated that sleep disturbances resulted in observable damage to the liver,lung,and kidney.Puerarin reversed multi-organ damage and inflammation.Further,puerarin activated paneth cells,resulting in increased lysozyme and TGF-βproduction,and stimulating intestinal stem cell proliferation.Puerarin also effectively inhibited the expression of F4/80,iNOS,TNF-α,and IL-1βin the small intestine,while it increased Chil3,CD206,and Arg-1 levels.Moreover,puerarin treatment significantly decreased P-P65,TLR4,Bcl-xl,and cleaved caspase-3 protein levels while increasing barrier protein levels,including ZO-1,Occludin,Claudin 1 and E-cadherin suggesting a reduction in inflammation and apoptosis in the gut.Overall,puerarin diminished systemic inflammation,particularly intestinal inflammation,and enhanced intestinal barrier integrity in mice with sleep disorders.Our findings suggest a potential new therapeutic pathway for sleep disorders.

Moxibustion regulates inflammatory mediators and colonic mucosal barrier in ulcerative colitis rats

AIM: To observe the efficacy and mechanism of grain-sized moxibustion at different acupoints in a rat model of ulcerative colitis (UC). METHODS: Sprague-Dawley rats were randomly divided into control, UC model, grain-sized moxibustion at a single acupoint (CV 12), grain-sized moxibustion at two acupoints (CV 12 and CV 4), grain-sized moxibustion at three acupoints (CV 12, CV 4, and ST 36), and medication groups (n = 8/group). The UC model was established by enema of trinitrobenzene sulfonic acid. Direct moxibustion was used once a day for 7 d. Disease activity index (DAI) was evaluated before and after the treatment. Morphologic changes of intestinal tissue were observed under an optical microscope. The expression of tumor necrosis factor (TNF)-alpha and p38 mitogen-activated protein kinase (p38MAPK) in colonic tissue was detected using Western blot, and the levels of occludin and zonula occludens-1 (ZO-1) mRNAs were detected using reverse transcription PCR. RESULTS: Compared with the control group, the intestinal mucosae were incomplete in the model group, glandular structures were irregular, and submucosae were edematous, hyperemic, and infiltrated with inflammatory cells. The DAI scores and expression of TNF-alpha and p38MAPK were increased significantly in the model group compared to controls (Ps < 0.01), while the mRNA levels of occludin and ZO-1 were reduced significantly (Ps < 0.01). Compared with the model group, colonic mucosa and the arrangement of glands were complete and regular in the treatment groups. DAI scores and the expression of TNF-alpha and p38MAPK were reduced significantly in moxibustion groups compared to controls (Ps < 0.01), while the mRNA levels of occludin and ZO-1 were increased significantly (Ps < 0.01). The improvements in the above indices in the three acupoints group and the medication group were superior to those in the single and two acupoints groups (all P < 0.05). CONCLUSION: Reduction of TNF-alpha and p38MAPK and increased expression of occludin and ZO-1 in colonic tissue represent a potential mechanism for improved intestinal mucosal tissue repair with grain-sized moxibustion.

Functional changes of intestinal mucosal barrier insurgically critical patients

BACKGROUND： The gut is capable of inducing multiple organ dysfunction syndrome （MODS）. In the diagnosis and treatment of critical ill patients, doctors should pay particular attention to the protection or recovery of intestinal barrier function. However, no reliable diagnostic criteria are available clinically. This study aimed to assess the changes of intestinal mucosal barrier function in surgically critical ill patients as well as their signi？ cance.METHODS： Thirty-eight surgically critical ill patients were enrolled as a study group （APACHE II〉8 scores）, and 15 non-critical ill patients without intestinal dysfunction were selected as a control group （APACHE II〈6）. General information, symptoms, physical signs, and APACHE II scores of the patients were recorded. The patients in the study group were subdivided into an intestinal dysfunction group （n=26） and a non-intestinal dysfunction group （n=12）. Three ml venous blood was collected from the control group on admission and the same volume of plasma was collected from the study group both on admission and in the period of recovery. The plasma concentrations of endotoxin, diamine oxidase （DAO）, D-lactate, and intestinal fatty-acid binding protein （iFABP） were detected respectively. The data collected were analyzed by the SPSS 17.0 software for Windows. RESULTS： The levels of variables were significantly higher in the study group than in the control group （P〈0.01）. They were higher in the intestinal dysfunction group than in the non-intestinal dysfunction group （DAO P〈0.05, endotoxin, D-lactate, iFABP P〈0.01）. In the non-intestinal dysfunction group compared with the control group, the level of endotoxin was not significant （P〉0.05）, but the levels of DAO, D-lactate and iFABP were statistically significant （P〈0.05）. The levels of variables in acute stage were higher than those in recovery stage （P〈0.01）.The death group showed higher levels of variables than the survival group （endotoxin and D-lactate P〈0.01, DAO and iFABP P〈0.05）.CONCLUSION： The plasma concentrations of endotoxin, DAO, D-lactate, and intestinal fatty-acid binding protein （iFABP） could re？ ect a better function of the intestinal mucosa barrier in surgically critical ill patients.

Resveratrol alleviates intestinal mucosal barrier dysfunction in dextran sulfate sodium-induced colitis mice by enhancing autophagy

BACKGROUND Intestinal mucosal barrier dysfunction plays an important role in the pathogenesis of ulcerative colitis(UC).Recent studies have revealed that impaired autophagy is associated with intestinal mucosal dysfunction in the mucosa of colitis mice.Resveratrol exerts anti-inflammatory functions by regulating autophagy.AIM To investigate the effect and mechanism of resveratrol on protecting the integrity of the intestinal mucosal barrier and anti-inflammation in dextran sulfate sodium(DSS)-induced ulcerative colitis mice.METHODS Male C57BL/6 mice were divided into four groups:negative control group,DSS model group,DSS+resveratrol group,and DSS+5-aminosalicylic acid group.The severity of colitis was assessed by the disease activity index,serum inflammatory cytokines were detected by enzyme-linked immunosorbent assay.Colon tissues were stained with haematoxylin and eosin,and mucosal damage was evaluated by mean histological score.The expression of occludin and ZO-1 in colon tissue was evaluated using immunohistochemical analysis.In addition,the expression of autophagy-related genes was determined using reverse transcription-polymerase chain reaction and Western-blot,and morphology of autophagy was observed by transmission electron microscopy.RESULTS The resveratrol treatment group showed a 1.72-fold decrease in disease activity index scores and 1.42,3.81,and 1.65-fold decrease in the production of the inflammatory cytokine tumor necrosis factor-α,interleukin-6 and interleukin-1β,respectively,in DSS-induced colitis mice compared with DSS group(P<0.05).The expressions of the tight junction proteins occludin and ZO-1 in DSS model group were decreased,and were increased in resveratrol-treated colitis group.Resveratrol also increased the levels of LC3B(by 1.39-fold compared with DSS group)and Beclin-1(by 1.49-fold compared with DSS group)(P<0.05),as well as the number of autophagosomes,which implies that the resveratrol may alleviate intestinal mucosal barrier dysfunction in DSS-induced UC mice by enhancing autophagy.CONCLUSION Resveratrol treatment decreased the expression of inflammatory factors,increased the expression of tight junction proteins and alleviated UC intestinal mucosal barrier dysfunction;this effect may be achieved by enhancing autophagy in intestinal epithelial cells.

Protective effect of exogenous IGF-I on the intestinal mucosal barrier in rats with severe acute pancreatitis

Severe acute pancreatitis （SAP） can result in intestinal mucosal barrier （IMB） dysfunction. This study was undertaken to demonstrate the effect of IGF-I on the intestinal mucosal barrier in rats with SAP and its possible mechanisms. Seventy-two male Wistar rats were randomly divided into three groups： a sham operation （SO group, n=24）, a SAP group not treated with IGF-I （SAP group, n=24）, and a SAP group treated with IGF-I （IGF-I group, n=24）. SAP was induced in the rats by injecting 5.0% sodium taurocholate into the biliary-pancreatic duct. The SO rats were given an infusion of normal saline instead. The rats in the IGF-I group underwent the SAP procedure and were given a subcutaneous injection of IGF-I at 30 minutes before the operation and at 3 hours after the operation. Eight rats in each group were sacrificed at 6, 12 and 24 hours after operation. Apoptosis of mucosal cells in the small intestine was determined by TUNEL. The levels of endotoxin and DAO and serum amylase were also measured. Pathologic changes in the small intestine were monitored. Changes of bax and bcl-2 mRNA expression in the small intestine were determined by reverse transcription polymerase chain reaction （RT-PCR）. The levels of serum amylase were lower in the IGF-I group than in the SAP group at all three time points （P〈0.05）. The levels of endotoxin in the IGF-I group were higher than those in the SAP group at 6 hours, but lower in the IGF-I group than in the SAP group at 12 and 24 hours （P〈0.05）. The levels of diamine oxidase were higher in the IGF-I group at 6 hours but lower than those in the SAP group at 12 and 24 hours. The pathological score of the small intestine was lower in the IGF-I group than in the SAP group, and the difference was statistically significant at 12 and 24 hours. The pathologic changes observed under electron microscopy were better in the IGF-I group than those in the SAP group. The apoptosis index of intestinal epithelial cells was significantly decreased in the IGF-I group compared with the SAP group. Compared with the SO group, the mRNA expression levels of bax were increased at each time point in the SAP group, and were significantly decreased in the IGF-I group as compared with the SAP group at each time point （P〈0.05）. The expression levels of bcl-2 were weak and not different between the SO group and the SAP group （P〉0.05）. They were significantly increased in the IGF-I group versus the SO and SAP groups （P〈0.05）. The ratio of bax and bcl-2 mRNA expression levels at each time point in the SAP group were significantly higher than those in the SO group, but they were obviously decreased in the IGF-I group. Exogenous IGF-I seems to protect mucosal cells in the small intestine against SAP-induced apoptosis and could alleviate SAP-induced injury of the intestinal mucosa. The underlying mechanisms include enhanced mRNA expression of bcl-2 and inhibition of bax mRNA expression.

Diverse expression patterns of mucin 2 in colorectal cancer indicates its mechanism related to the intestinal mucosal barrier

BACKGROUND Abnormal expression patterns of mucin 2(MUC2)have been reported in a variety of malignant tumors and precancerous lesions.Reduced MUC2 expression in the intestinal mucosa,caused by various pathogenic factors,is related to mechanical dysfunction of the intestinal mucosa barrier and increased intestinal mucosal permeability.However,the relationship between MUC2 and the intestinal mucosal barrier in patients with colorectal cancer(CRC)is not clear.AIM To explore the relationship between MUC2 and intestinal mucosal barrier by characterizing the multiple expression patterns of MUC2 in CRC.METHODS Immunohistochemical staining was performed on intestinal tissue specimens from 100 CRC patients,including both cancer tissues and adjacent normal tissues.Enzyme-linked immunosorbent assays were performed on preoperative sera from 66 CRC patients and 20 normal sera to detect the serum levels of MUC2,diamine oxide(DAO),and D-lactate(D-LAC).The relationship between MUC2 expression and clinical parameters was calculated by theχ2 test or Fisher’s exact test.Prognostic value of MUC2 was evaluated by Kaplan-Meier curve and log-rank tests.RESULTS Immunohistochemical staining of 100 CRC tissues showed that the expression of MUC2 in cancer tissues was lower than that in normal tissues(54%vs 79%,P<0.05),and it was correlated with tumor-node-metastasis(TNM)stage and lymph node metastasis in CRC patients(P<0.05).However,the serum level of MUC2 in CRC patients was higher than that in normal controls,and was positively associated with serum levels of human DAO(χ2=3.957,P<0.05)and D-LAC(χ^(2)=7.236,P<0.05),which are the biomarkers of the functional status of the intestinal mucosal barrier.And the serum level of MUC2 was correlated with TNM stage,tumor type,and distant metastasis in CRC patients(P<0.05).Kaplan-Meier curves showed that decreased MUC2 expression in CRC tissues predicted a poor survival.CONCLUSION MUC2 in tissues may play a protective role by participating in the intestinal mucosal barrier and can be used as an indicator to evaluate the prognosis of CRC patients.

Dahuang Fuzi decoction reduces inflammation levels and alleviates intestinal mucosal barrier damage in septic rats

Objective:To investigate the protective effect of Dahuang Fuzi Decoction(DHFZD),a traditional Chinese prescription,at alleviating sepsis-induced inflammation and gut barrier damage in rats.Methods:Forty clean-grade male Sprague-Dawley rats were divided randomly into three groups:normal control group(NCG,n?10),model control group(MCG,n?15)and DHFZD-treated group(DHFZDG,n?15).NCG rats were sham operated on and used as the controls,whereas MCG and DHFZDG rats were used to replicate the rat sepsis model using cecal ligation and puncture(CLP).The DHFZDG rats received DHFZD by gavage(4.5 mg/g of body weight)2 h prior to CLP and after its successful induction,while the NCG and MCG rats received equivalent amounts of sterilized water by gavage.All rat groups were starved and had free access to water.At 24 h post-experimental set up,the mortality of rats in each group was recorded,and peritoneal inflammation assessment and pathological changes related to the intestinal mucosal injury index(IMII)in the surviving rats were evaluated.D-lactic acid,tumor necrosis factor(TNF)-a,interleukin(IL)-6 and IL-10 peripheral blood concentrations,along with secretory immunoglobulin A(sIgA)in the intestinal mucosa were evaluated by enzyme-linked immunosorbent assays.Gut microbes were detected using 16S rRNA gene sequencing.Results:DHFZD reduced sepsis-related mortality in the rats.Moreover,it alleviated peritoneal inflammation and pathological changes according to the IMII.DHFZD reduced serum procalcitonin,TNF-a and IL-6 concentrations,but not the IL-10 concentration.It also reduced serum D-lactic acid and increased sIgA concentrations in intestinal mucosa.Notably,DHFZDG restored gut microbiota diversity and regulated the decrease in Bacteroidetes induced by sepsis,compared with the MCG rats.Conclusion:DHFZDG may play a protective role in sepsis by alleviating sepsis-induced inflammation and gut barrier damage in rats.

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

Objective This 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.Methods By 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 macrophages in spleen.16S rRNA sequencing was performed to detect the intestinal microbiota structure of mice.Results Bacillus 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 swelling improved,colon histopathological injury was alleviated,inflammatory cell infiltration was alleviated,serum IL-10 increased significantly,LPS、TNF-αand IL-6 decreased significantly compared with model group,and the proportion of T cells and intestinal dysbiosis was improved.Conclusions The 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.

Effects of Faecalibacterium prausnitzii intervention on immune response, intestinal flora and intestinal mucosal barrier of mice with ulcerative colitis

Objective: To study the effects of Faecalibacterium prausnitzii intervention on immune response, intestinal flora and intestinal mucosal barrier of mice with ulcerative colitis (UC). Methods: C57BL/6J mice were randomly divided into control group, UC group and Faecalibacterium prausnitzii group, the latter two groups were made into UC models by trinitrobenzene sulfonic acid enema and F. prausnitzii group were given intragastric administration of F. prausnitzii solution for intervention. The differences in immune response, intestinal flora, and intestinal mucosal barrier were compared among the three groups after 7 days of intervention. Results: The interleukin-10 (IL-10) and transforming growth factor-β1 (TGF-β1) contents in serum, the fork head box P3 (Foxp3), zonula occludens-1 (ZO-1), occludin, claudin-1 and claudin-2 expression in intestinal mucosa as well as the number of bifidobacterium and lactobacillus in feces of the UC group were significantly lower than those of the control group whereas the interleukin-17 (IL-17), diamine oxidase (DAO) and D-lactic acid (D-LA) contents in serum, the retinoid-related orphan nuclear receptor γt (RORγt) expression in intestinal mucosa as well as the number of enterobacter and enterococcus in feces were significantly higher than those of the control group (P<0.05);IL-10 and TGF-β1 contents in serum, Foxp3, ZO-1, occludin, claudin-1 and claudin-2 expression in intestinal mucosa as well as the number of bifidobacterium and lactobacillus in feces of the F. prausnitzii group were significantly higher than those of the UC group whereas IL-17, DAO and D-LA contents in serum, RORγt expression in intestinal mucosa as well as the number of enterobacter and enterococcus in feces were significantly lower than those of the UC group (P<0.05). Conclusion: Faecalibacterium prausnitzii intervention can improve the Th17/Treg immune response, intestinal flora and intestinal mucosal barrier in UC mice.

Intestinal mucosal barrier in functional constipation:Dose it change?

BACKGROUND The intestinal mucosal barrier is the first line of defense against numerous harmful substances,and it contributes to the maintenance of intestinal homeostasis.Recent studies reported that structural and functional changes in the intestinal mucosal barrier were involved in the pathogenesis of several intestinal diseases.However,no study thoroughly evaluated this barrier in patients with functional constipation(FC).AIM To investigate the intestinal mucosal barrier in FC,including the mucus barrier,intercellular junctions,mucosal immunity and gut permeability.METHODS Forty FC patients who fulfilled the Rome IV criteria and 24 healthy controls were recruited in the Department of Gastroenterology of China-Japan Friendship Hospital.The colonic mucus barrier,intercellular junctions in the colonic epithelium,mucosal immune state and gut permeability in FC patients were comprehensively examined.Goblet cells were stained with Alcian Blue/Periodic acid Schiff(AB/PAS)and counted.The ultrastructure of intercellular junctional complexes was observed under an electron microscope.Occludin and zonula occludens-1(ZO-1)in the colonic mucosa were located and quantified using immunohistochemistry and quantitative real-time polymerase chain reaction.Colonic CD3+intraepithelial lymphocytes(IELs)and CD3+lymphocytes in the lamina propria were identified and counted using immunofluorescence.The serum levels of D-lactic acid and zonulin were detected using enzyme-linked immunosorbent assay.RESULTS Compared to healthy controls,the staining of mucus secreted by goblet cells was darker in FC patients,and the number of goblet cells per upper crypt in the colonic mucosa was significantly increased in FC patients(control,18.67±2.99;FC,22.42±4.09;P=0.001).The intercellular junctional complexes in the colonic epithelium were integral in FC patients.The distribution of mucosal occludin and ZO-1 was not altered in FC patients.No significant differences were found in occludin(control,5.76E-2±1.62E-2;FC,5.17E-2±1.80E-2;P=0.240)and ZO-1(control,2.29E-2±0.93E-2;FC,2.68E-2±1.60E-2;P=0.333)protein expression between the two groups.The mRNA levels in occludin and ZO-1 were not modified in FC patients compared to healthy controls(P=0.145,P=0.451,respectively).No significant differences were observed in the number of CD3+IELs per 100 epithelial cells(control,5.62±2.06;FC,4.50±2.16;P=0.070)and CD3+lamina propria lymphocytes(control,19.69±6.04/mm^(2);FC,22.70±11.38/mm^(2);P=0.273).There were no significant differences in serum D-lactic acid[control,5.21(4.46,5.49)mmol/L;FC,4.63(4.31,5.42)mmol/L;P=0.112]or zonulin[control,1.36(0.53,2.15)ng/mL;FC,0.94(0.47,1.56)ng/mL;P=0.185]levels between FC patients and healthy controls.CONCLUSION The intestinal mucosal barrier in FC patients exhibits a compensatory increase in goblet cells and integral intercellular junctions without activation of mucosal immunity or increased gut permeability.

Berberine Enhances Intestinal Mucosal Barrier Function by Promoting Vitamin D Receptor Activity

Objective:To evaluate if berberine can act on vitamin D receptors(VDR)and thereby regulate the expression of tight junction proteins(TJPs)in irritable bowel syndrome-diarrhea-predominant(IBS-D)rats.Methods:The newborn rats were induced into IBS-D rat model via neonatal maternal separation combined with acetic acid chemical stimulation.After modeling,the model was evaluated and rats were divided into the control group and berberine treatment groups(0.85,1.7 and 3.4 mg/kg,once a day for 2 weeks).The distal colon was obtained and colonic epithelial cells(CECs)were isolated and cultured after IBS-D model evaluation.The vitamin D receptor response element(VDRE)reporter gene was determined in the CECs of IBS-D rats to analyze the effect of berberine on the VDRE promoter.VDR overexpression or silencing technology was used to analyze whether VDR plays a role in promoting intestinal barrier repair,and to determine which region of VDR plays a role in berberine-regulated intestinal TJPs.Results:The IBS-D rat model was successfully constructed and the symptoms were improved by berberine in a dose-dependent manner(P<0.05).The activity of VDRE promoter was also effectively promoted by berberine(P<0.05).Berberine increased the expression of TJPs in IBS-D CECs(P<0.05).VDR expression was significantly increased after transfection of different domains of VDR when compared to normal control and basic plasmid groups(all P<0.05).RT-qPCR and Western blot results showed that compared with the blank group,expressions of occludin and zonula occludens-1 were significantly higher in VDR containing groups(all P<0.05).Berberine plus pCMV-Myc-VDR-N group exerted the highest expression levels of occludin and zonula occludens-1(P<0.05).Conclusion:Berberine enhances intestinal mucosal barrier function of IBS-D rats by promoting VDR activity,and the main site of action is the N-terminal region of VDR.

PEGylated bacteria restore intestinal mucosal barrier

The mucosal barrier of the gastrointestinal tract(GIT)is crucial for the overall health of the body.Its disruption permits the infiltration of intestinal microorganisms into the underlying mucosa,resulting in infections and inflammatory conditions,such as inflammatory bowel disease(IBD),metabolic disorders,and autoimmune diseases^(1,2).Therefore,strategies to protect the mucosal barrier from exogenous stimuli or to facilitate its recovery have become increasingly important.Currently,immunomodulators,corticosteroids,and biological agents have been widely employed to treat IBD by alleviating inflammation and enhancing mucosal healing.Unfortunately,they can also produce serious systemic toxicity^(3,4);therefore,there is an urgent need for exploiting innovative strategies to fortify the intestinal mucosal barrier against the invasion of exogenous damaging factors.

Simple and versatile in situ thermo-sensitive hydrogel for rectal administration of SZ-A to alleviate inflammation and repair mucosal barrier in ulcerative colitis

Ulcerative colitis(UC)is a chronic inflammatory bowel disease characterized by persistent inflammation of the colon and disrupted intestinal function.Ramulus mori(Sangzhi)alkaloids(SZ-A),derived from twigs of mulberry,were approved by the National Medical Products Administration in 2020 for treating type 2 diabetes mellitus.Accumulated evidence has confirmed that SZ-A also alleviates non-alcoholic fatty liver disease and ameliorates inflammation,indicating its potential to address inflammation in UC.However,the treatment of UC faces challenges due to low drug delivery efficiency and short retention time.To overcome these challenges,an injectable and adherent in-situ thermo-sensitive hydrogel containing SZ-A was developed for rectal drug delivery,utilizing the thermo-sensitive polymers Poloxamer 407and 188.The thermo-sensitive hydrogel system was designed with a moderate gelation temperature of 32±0.5℃,a short gelation time of 64 s,a p H range of 7-10,high moisturizing capability exceeding 90%,and moderate mechanical strength of 4-5 s.In a rat model with UC,the in situ thermo-sensitive hydrogel significantly extended the retention time at the colonic site and enabled sustained release after rectal administration.Symptoms of UC were markedly reduced following rectal administration of SZ-A thermosensitive hydrogel.Furthermore,the release of inflammatory factors,such as interleukin-1β(IL-1β),IL-6,IL-18,tumor necrosis factor-α(TNF-α),and transforming growth factor-β1(TGF-β1),significantly decreased in the SZ-A thermo-sensitive hydrogel group.The integrity of the colonic mucosal barrier was significantly enhanced following the application of SZ-A thermo-sensitive hydrogel.In conclusion,rectal administration of SZ-A in situ thermo-sensitive hydrogel effectively alleviated UC symptoms,inhibited the secretion of inflammatory factors,and promoted the repair of the colonic mucosal barrier.This approach holds promise as a potential treatment for UC.

Lactobacillus intestinalis/Lactobacillus rhamnosus protects against AFB_(1)-induced liver damage:involvement of intestinal mucosal barrier

Aflatoxin B1(AFB1)is a widely spread mycotoxin that poses a threat to the healthy to human and animals.The liver is the main target organ for AFB1-induced damage,primarily causing inflammatory injury and oxidative stress.When AFB1 enters the body,it can damage the intestinal barrier function,and its metabolites are transported to the liver.Therefore,the damage to the liver is closely associated with intestinal barrier impairment.Lactobacillus plays a crucial role in mitigating liver damage by improving the intestinal barrier function.In our previous report,we reported that Lactobacillus reduces liver damage caused by AFB1.However,it is still unclear how the intestinal barrier contributes to the protective effects of Lactobacillus against AFB1.To investigate the protective effects and intestinal barrier mechanisms of Lactobacillus intestinals/rhamnosus against AFB1-induced liver damage,we orally administered AFB1 and Lactobacillus intestinals/rhamnosus to male SD rats.Then the body weight,organ index,histopathological changes in the liver and gut,liver and kidney function indicators,intestinal mucosal barrier indicators,serum AFB1 content and inflammatory factors,liver oxidative stress index,and short-chain fatty acids content were analyzed.Our findings demonstrate that exposure to AFB1 resulted in changes in liver histopathology and biochemical functions,altered inflammatory response and oxidative stress,compromised the intestinal mucosal barrier,and induced the accumulation of inflammatory factor and inflammation in the liver.However,supplementation with Lactobacillus intestinals or Lactobacillus rhamnosus significantly prevented AFB1-induced liver injury,alleviated histopathological changes and hepatic injury by the maintenance of intestinal mucosal barrier integrity.

Rhubarb Monomers Protect Intestinal Mucosal Barrier in Sepsis via Junction Proteins

Background： Leakage of the intestinal mucosal barrier may cause translocation of bacteria, then leading to multiorgan lhilure. This study hypothesized that rhubarb monomers might protect the gut mucosal barrier in sepsis through junction proteins. Methods： Healthy male Sprague-Dawley rats （weighing 230-250 g） tinder anesthesia and sedation were subjected to cecal ligation and perforation （CLP）. After surgical preparation, rats were randornly assigned to eight groups （n = 6 or 8 each group）： sham group （Group A： normal saline gavage）; sepsis group （Group B： nomlal saline gavage）; Group C （intraperitoneally, dexamethasone 0.5 mg/kg） immediately after CLP surgery; and rhubarb monomer （ 100 mg/kg in normal saline）-treated groups （Group D： rhein： Group E： emodin; Group F： 3,8-dihydroxy- l-methyl-anthraquinone-2-carboxylic acid; Group G： 1-O-caffeoyl-2-（4-hydroxy-O-cinnamoyl）-D-glucose; and Group H： daucosterol linoleate）. Animals were sacrificed after 24 h. Intestinal histology, lactulose, mannito[ concentrations were measured, and zonula occludens （ZO）-I, occludin and claudin-5 transcription （polymerase chain reaction）, translation （by Western blot analysis）, and expression （by immunohistochemistry） were also measured. Results： Intestinal histology revealed injury to intestinal mucosal villi induced by sepsis in Group B, compared with Group A. Compared with Group A （0.17 ± 0.41 ）, the pathological scores in Groups B （2.83 ± 0.41, P 〈 0.001）, C （ 1.83 ± 0.41, P 〈 0.001 ）, D （2.00 ± 0.63, P 〈 0.001）, E （ 1.83 ± 0.41, P 〈 0.001 ）, F （ 1.83 ± 0.75, P 〈 0.001 ）, G （2.17 ± 0.41, P 〈 0.001 ）,and H （ 1.83 ± 0.41, P 〈 0.001 ） were significantly increased. Lactulose/mannitol （L/M） ratio in Group B （0.046 ± 0.003） was significantly higher than in Group A （0.013 ± 0.001, P 〈 0.001） while L/M ratios in Groups C （0.028 ± 0.002, P 〈 0.001 ）, D （0.029 ± 0.003, P 〈 0.001 ）, E （0.026 ± 0.003, P 〈 0.001 ）, F （0.027 ± 0.003, P 〈 0.001 ）, G （0.030 ± 0.005, P 〈 0.001 ）, and H （0.026 ± 0.002, P 〈 0.001 ） were significantly lower than that in Group B. ZO- 1, occludin and claudin-5 transcription, translation, and expression in Group B were significantly lower than that in Group A （P 〈 0.001 ）, but they were significantly higher in Groups C, D, E, F, G, and H than those in Group B （P 〈 0.05）. Conclusion： Rhubarb monomer treatment ameliorated rnucosal damage in sepsis via enhanced transcription, translation, and expression of junction proteins.

Heat stress-induced mucosal barrier dysfunction is potentially associated with gut microbiota dysbiosis in pigs

Heat stress(HS)can be detrimental to the gut health of swine.Many negative outcomes induced by HS are increasingly recognized as including modulation of intestinal microbiota.In turn,the intestinal microbiota is a unique ecosystem playing a critical role in mediating the host stress response.Therefore,we aimed to characterize gut microbiota of pigs’exposure to short-term HS,to explore a possible link between the intestinal microbiota and HS-related changes,including serum cytokines,oxidation status,and intestinal epithelial barrier function.Our findings showed that HS led to intestinal morphological and integrity changes(villus height,serum diamine oxidase[DAO],serum D-lactate and the relative expressions of tight junction proteins),reduction of serum cytokines(interleukin[IL]-8,IL-12,interferongamma[IFN-g]),and antioxidant activity(higher glutathione[GSH]and malondialdehyde[MDA]content,and lower superoxide dismutase[SOD]).Also,16S rRNA sequencing analysis revealed that although there was no difference in microbial a-diversity,some HS-associated composition differences were revealed in the ileum and cecum,which partly led to an imbalance in the production of short-chain fatty acids including propionate acid and valerate acid.Relevance networks revealed that HS-derived changes in bacterial genera and microbial metabolites,such as Chlamydia,Lactobacillus,Succinivibrio,Bifidobacterium,Lachnoclostridium,and propionic acid,were correlated with oxidative stress,intestinal barrier dysfunction,and inflammation in pigs.Collectively,our observations suggest that intestinal damage induced by HS is probably partly related to the gut microbiota dysbiosis,though the underlying mechanism remains to be fully elucidated.

Mechanism of Shengmai Injection on Anti-Sepsis and Protective Activities of Intestinal Mucosal Barrier in Mice

Objective:To study the mechanism of Shengmai Injection(SMI)on anti-sepsis and protective activities of intestinal mucosal barrier.Methods:The contents of 11 active components of SMI including ginsenoside Rb1,Rb2,Rb3,Rd,Re,Rf,Rg1,Rg2,ophioposide D,schisandrol A and schisantherin A were determined using ultra-performance liquid chromatography.Fifty mice were randomly divided into the blank,the model,the low-,medium-and high-dose SMI groups(0.375,0.75,1.5 mL/kg,respectively)by random number table,10 mice in each group.On SMI group,SMI was administrated to mice daily via tail vein injection for 3 consecutive days,while the mice in the blank and model groups were given 0.1 mL of normal saline.One hour after the last SMI administration,except the blank group,the mice in other groups were intraperitoneally injected with lipopolysaccharide(LPS)saline solution(2 mL/kg)at a dosage of 5 mL/kg for development of endotoxemia mice model.The mice in the blank group were given the same volume of normal saline.Inflammatory factors including interferon-γ(INF-γ),tumor necrosis factor-α(TNF-α),interleukin(IL)-2 and IL-10 were measured by flow cytometry.Myosin light-chain kinase(MLCK),nuclear factorκB(NF-κB)levels,and change of Occludin proteins in jejunum samples were analyzed by Western blot.Results:The decreasing trends of INF-γ,TNF-α and IL-2 were found in serum of SMI treatment groups.In SMI-treated mice,the content of Occludin increased and MLCK protein decreased compared with the model group(P<0.05 or P<0.01).The content of cellular and nuclear NF-κB did not change significantly(P>0.05).Conclusion:SMI may exert its anti-sepsis activity mainly through NF-κB-pro-inflammatory factor-MLCK-TJ cascade.

Interferon-β induced in female genital epithelium by HIV-1 glycoprotein 120 via Toll-like-receptor 2 pathway acts to protect the mucosal barrier

More than 40%of HIV infections occur via female reproductive tract(FRT)through heterosexual transmission.Epithelial cells that line the female genital mucosa are the first line of defense against HIV-1 and other sexually transmitted pathogens.These sentient cells recognize and respond to external stimuli by induction of a range of carefully balanced innate immune responses.Previously,we have shown that in response to HIV-1 gp120,the genital epithelial cells(GECs)from upper reproductive tract induce an inflammatory response that may facilitate HIV-1 translocation and infection.In this study,we report that the endometrial and endocervical GECs simultaneously induce biologically active interferon-β(IFNβ)antiviral responses following exposure to HIV-1 that act to protect the epithelial tight junction barrier.The innate antiviral response was directly induced by HIV-1 envelope glycoprotein gp120 and addition of gp120 neutralizing antibody inhibited IFNβproduction.Interferon-βwas induced by gp120 in upper GECs through Toll-like receptor 2 signaling and required presence of heparan sulfate on epithelial cell surface.The induction of IFNβwas dependent upon activation of transcription factor IRF3(interferon regulatory factor 3).The IFNβwas biologically active,had a protective effect on epithelial tight junction barrier and was able to inhibit HIV-1 infection in TZM-bl indicator cells and HIV-1 replication in T cells.This is the first report that recognition of HIV-1 by upper GECs leads to induction of innate antiviral pathways.This could explain the overall low infectivity of HIV-1 in the FRT and could be exploited for HIV-1 prophylaxis.