Zonula Occludens-1 Protein Expression Research Articles

Mechanisms of Peitu Yimu acupuncture in repairing intestinal mucosal barrier by regulating CRF/CRFR1 pathway in diarrhea-predominant irritable bowel syndrome rats.

To investigate the effect of Peitu Yimu(strengthening spleen and soothing liver) acupuncture on intestinal mucosal barrier function and corticotropin-releasing factor (CRF)/CRF receptor 1 (CRFR1) pathway in rats with diarrhea-predominant irritable bowel syndrome (IBS-D), so as to explore its underlying mechanism in alleviating IBS-D. Forty female SD rats were randomly divided into blank, model, electroacupuncture (EA), and agonist groups, with 10 rats in each group. Except for the blank group, rats in the other groups were given folium sennae infusion by gavage combined with chronic unpredictable mild stress to establish IBS-D model. Rats in the EA group received acupuncture at "Tianshu"(ST25) and EA at "Zusanli"(ST36) and "Taichong"(LR3) (2 Hz/15 Hz) on one side for 20 min, with the side chosen alternately every other day, for 14 days after modeling. Rats in the agonist group received acupuncture 30 min after intravenous injection of CRFR1 agonist urocortin, with the same manipulation method and time as the EA group. Before and after intervention, visceral pain threshold and stool Bristol scores were measured. Elevated plus maze test and open field test were used to detect anxiety and depression like behavior of rats. ELISA was used to detect the contents of CRF and CRFR1 in rats serum. Immunohistochemistry was used to detect the positive expressions of CRF, CRFR1, zonula occludens protein 1(ZO-1), occlusal protein(Occludin), and closure protein 1 (Claudin-1) in colon tissue. Compared with the blank group, the visceral pain threshold, open arm time percentage (OT%), total distance of movement in the open field test, and positive expression of ZO-1, Occludin, and Claudin-1 in colon were decreased (P<0.01, P<0.05), while Bristol stool scores, serum CRF and CRFR1 contents, and positive expressions of CRF and CRFR1 in colon were increased (P<0.01) in the model group. After intervention and compared with the model group, the visceral pain threshold, OT%, total distance of movement in the open field test, and positive expressions of ZO-1, Occludin, and Claudin-1 in colon were increased (P<0.05, P<0.01), while Bristol stool scores, serum CRF and CRFR1 contents, and positive expressions of CRF and CRFR1 in colon were decreased (P<0.01) in the EA group；the Bristol stool scores, serum CRF content, and CRF positive expression in colon were significantly decreased in the agonist group (P<0.01). Peitu Yimu acupuncture can significantly improve visceral hypersensitivity and anxiety-depression state in IBS-D rats. Its mechanism may be related to the inhibition of CRF/CRFR1 pathway and restoration of intestinal tight junction protein expressions.

Improving Intestinal Barrier Function in Sepsis by Partially Hydrolysed Guar Gum via the Suppression of the NF-κB/MLCK Pathway.

Partially hydrolyzed guar gum (PHGG) protects against intestinal barrier dysfunction and can ameliorate some intestinal diseases. However, whether PHGG has a role in protecting intestinal barrier function (IBF) during sepsis remains unclear. This study aimed to investigate the role and probable mechanism of PHGG in the intestinal mucosa in sepsis. A rat sepsis model was constructed using cecal ligation and puncture (CLP). FITC-dextran 4 (FD-4) flux, serum inflammatory mediator levels, tight junction (TJ) levels, jejunum mucosa pathology, and epithelial intercellular junction ultrastructure were monitored to evaluate the effect of PHGG on IBF. Caco-2 monolayers were used to study the impact and mechanism of PHGG on lipopolysaccharide (LPS)-induced barrier dysfunction in vitro. The expression of zonula occludens protein-1 and occludin and the location of P65 were studied by immunofluorescence. Nuclear factor kappa B (NF-κB) and myosin light chain kinase 3 (MLCK) pathway-related protein expression was verified by quantitative reverse transcriptase polymerase chain reaction or western blotting. The results indicated that the jejunal mucosa structure was destroyed, the villi were disrupted and shortened, and neutrophil infiltration was evident in the septic rats. Compared to Sham group, spetic rats had increased Chiu's score, serum inflammatory mediator levels, and FD-4 flux but decreased TJ and gap junction density. In addition, the expression of MLCK, p-MLC, and TJ proteins and the expression of P65 in the nucleus were increased in septic rats. Furthermore, compared to those in the Control group, LPS-treated Caco-2 cells showed lower cell viability and transepithelial electrical resistance, while had higher FD-4 flux and the expression of MLCK, p-MLC, TJ proteins and P65 in the nucleus. PHGG pretreatment reversed the above effects induced by CLP or LPS treatment. Moreover, SN50, an NF-κB inhibitor, attenuated the above effects of LPS on Caco-2 cells. Overall, PHGG reduced inflammation, increased TJ protein expression and localization, and relieved damage to the TJ structure and intestinal permeability through suppression of the NF-κB/MLCK pathway. This study provides new insights into the role of PHGG in sepsis therapy.

Punicalagin ameliorates DSS-induced colitis in mice through strengthening gut barrier, decreasing oxidative stress and downregulating inflammation via AMPK–NF–κB-STAT3 pathway

Inflammatory bowel disease is characterized by compromised epithelium barrier function and hyperactive intestinal inflammation. This study aims to investigate the effects of punicalagin, a bioactive ellagitannin in pomegranate, on dextran-sodium sulfate (DSS) - induced colitis in mice and to examine the underlying mechanisms involved. Oral administration of punicalagin (100 mg/kg/day) effectively mitigated the severity of experimental colitis in mice, evidenced by increased colon length, improved intestinal permeability, and decreased histological scores. Punicalagin up-regulated the mRNA expression level of Muc2 in and the protein expression of zonula occludens-1 (ZO-1) and Occludin in colitic mice. Moreover, punicalagin effectively decreased reactive oxygen species (ROS) levels in the colon, and in Caco-2 cells exposed to H2O2in vitro. Mechanistically, punicalagin attenuated inflammation by inhibiting the secretion of interleukin-6 (IL-6) and the phosphorylation of the NF-κB/STAT3 pathway. In addition, punicalagin increased adenosine monophosphate activated protein kinase (AMPK) phosphorylation in the colon of DSS-treated mice and lipopolysaccharide (LPS) -induced RAW 264.7 macrophages. Knocking down AMPKα by siRNA diminished punicalagin's anti-inflammatory function in RAW 264.7 macrophages exposed to LPS. Furthermore, molecular docking analysis, cellular thermal shift assay (CETSA), and drug affinity responsive target stability (DARTS) analysis supported the direct interaction between punicalagin and AMPK. In conclusion, punicalagin could mitigate DSS-induced colitis through enhancing intestinal epithelial barrier, alleviating oxidative stress, and attenuating inflammation partly through modulation of AMPK–NF–κB-STAT3 pathway.

Effects of moxibustion on intestinal barrier function and TLR4/NF-κB p65 signaling pathway in obese rats.

To observe the effects of moxibustion on intestinal barrier function and Toll-like receptor 4 (TLR4)/nuclear factor-κB p65 (NF-κB p65) signaling pathway in obese rats and explore the mechanism of moxibustion in the intervention of obesity. Fifty-five Wistar rats of SPF grade were randomly divided into a normal group (10 rats) and a modeling group (45 rats). In the modeling group, the obesity model was established by feeding high-fat diet. Thirty successfully-modeled rats were randomized into a model group, a moxibustion group, and a placebo-control group, with 10 rats in each one. In the moxibustion group, moxibustion was applied at the site 3 cm to 5 cm far from the surface of "Zhongwan" (CV 12), with the temperature maintained at (46±1 ) ℃. In the placebo-control group, moxibustion was applied at the site 8 cm to 10 cm far from "Zhongwan" (CV 12), with the temperature maintained at (38±1) ℃. The intervention was delivered once daily for 8 weeks in the above two groups. The body mass and food intake of the rats were observed before and after intervention in each group. Using ELISA methool, the levels of serum triacylglycerol (TG), total cholesterol (TC) and lipopolysaccharide (LPS) were detected and the insulin resistance index (HOMA-IR) was calculated. HE staining was used to observe the morphology of colon tissue. The mRNA expression of zonula occludens-1 (ZO-1), Occludin, Claudin-1, TLR4 and NF-κB p65 in the colon tissue was detected by quantitative real-time PCR; and the protein expression of ZO-1, Occludin, Claudin-1, TLR4 and NF-κB p65 was detected by Western blot in the rats of each group. Compared with the normal group, the body mass, food intake, the level of HOMA-IR, and the serum levels of TC, TG and LPS were increased in the rats of the model group (P<0.01); those indexes in the moxibustion group were all reduced when compared with the model group and the placebo-control group respectively (P<0.01, P<0.05). Compared with the normal group, a large number of epithelial cells in the mucosa of colon tissue was damaged, shed, and the inflammatory cells were infiltrated obviously in the interstitium in the rats of the model group. When compared with the model group, in the moxibustion group, the damage of the colon tissue was recovered to various degrees and there were few infiltrated inflammatory cells in the interstitium, while, the epithelial injury of the colon tissue was slightly recovered and the infiltrated inflammatory cells in the interstitium were still seen in the placebo-control group. The mRNA and protein expressions of ZO-1, Occludin and Caudin-1 were decreased in the model group compared with those in the normal group (P<0.01). When compared with the model group and the placebo-control group, the mRNA and protein expressions of these indexes were increased in the moxibustion group (P<0.01, P<0.05). In the model group, the mRNA and protein expressions of TLR4 and NF-κB p65 were increased when compared with those in the normal group (P<0.01), and the mRNA and protein expressions of these indexes were reduced in the moxibustion group when compared with those in the model group and the placebo-control group (P<0.01). Moxibustion can reduce the body mass and food intake, regulate the blood lipid and improve insulin resistance in the rats of obesity. It may be related to alleviating inflammatory response through improving intestinal barrier function and modulating the intestinal TLR4/NF-κB p65 signaling pathway.

Cepharanthine maintains integrity of the blood-brain barrier (BBB) in stroke via the VEGF/VEGFR2/ZO-1 signaling pathway.

Dysfunction of tight junctions such as zonula occludens protein-1 (ZO-1)-associated aggravation of blood-brain barrier (BBB) permeability plays an important role in the progression of stroke. Cepharanthine (CEP) is an extract from the plant Stephania cepharantha. However, the effects of CEP on stroke and BBB dysfunction have not been previously reported. In this study, we report that CEP improved dysfunction in neurological behavior in a middle cerebral artery occlusion (MCAO) mouse model. Importantly, CEP suppressed blood-brain barrier (BBB) hyperpermeability by increasing the expression of ZO-1. Notably, we found that CEP inhibited the expression of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor 2 (VEGFR2) in the cortex of MCAO mice. Additionally, the results of in vitro experiments demonstrate that treatment with CEP ameliorated cytotoxicity of human bEnd.3 brain microvascular endothelial cells against hypoxia/reperfusion (H/R). Also, CEP attenuated H/R-induced aggravation of endothelial permeability in bEND.3 cells by restoring the expression of ZO-1. Further study proved that the protective effects of CEP are mediated by inhibition of VEGF-A and VEGFR2. Based on the results, we conclude that CEP might possess a therapeutic prospect in stroke through protecting the integrity of the BBB mediated by the VEGF/VEGFR2/ZO-1 axis.

Comparative Study of the Effects of Dietary-Free and -Bound Nε-Carboxymethyllysine on Gut Microbiota and Intestinal Barrier.

Nε-carboxymethyllysine (CML) is produced by a nonenzymatic reaction between reducing sugar and ε-amino group of lysine in food and exists as free and bound forms with varying digestibility and absorption properties in vivo, causing diverse interactions with gut microbiota. The effects of different forms of dietary CML on the gut microbiota and intestinal barrier of mice were explored. Mice were exposed to free and bound CML for 12 weeks, and colonic morphology, gut microbiota, fecal short-chain fatty acids (SCFAs), intestinal barrier, and receptor for AGE (RAGE) signaling cascades were measured. The results indicated that dietary-free CML increased the relative abundance of SCFA-producing genera including Blautia, Faecalibacterium, Agathobacter, and Roseburia. In contrast, dietary-bound CML mainly increased the relative abundance of Akkermansia. Moreover, dietary-free and -bound CML promoted the gene and protein expression of zonula occludens-1 and claudin-1. Additionally, the intake of free and bound CML caused an upregulation of RAGE expression but did not activate downstream inflammatory pathways due to the upregulation of oligosaccharyl transferase complex protein 48 (AGER1) expression, indicating a delicate balance between protective and proinflammatory effects in vivo. Dietary-free and -bound CML could modulate the gut microbiota community and increase tight-junction expression, and dietary-free CML might exert a higher potential benefit on gut microbiota and SCFAs than dietary-bound CML.

Tannic acid and zinc ion coordination of nanase for the treatment of inflammatory bowel disease by promoting mucosal repair and removing reactive oxygen and nitrogen species

Colon mucosal overexpression of reactive oxygen and nitrogen species (RONS) accelerates the development of inflammatory bowel disease (IBD) and destroys the mucosa and its barrier. IBD can be alleviated by removing RONS from the inflamed colon. The preparation of strong and efficient nanoantioxidants remains a challenge despite the development of numerous nanoantioxidants. In this paper, Zn-TA nanoparticles with fine hollow microstructure (HZn-TA) were successfully prepared and could be effectively used to treat IBD. In the first step, ZIF-8 nanoparticles were synthesized by a one-pot method. On this basis, HZn-TA nanoparticles were etched by TA, and a multifunctional nanase was developed for the treatment of IBD. RONS, including reactive oxygen species (ROS) and nitric oxide (NO), can be eliminated to increase cell survival following Hydrogen peroxide (H2O2) stimulation, including reactive oxygen species (ROS) and nitric oxide (NO with hydrogen peroxide (H2O2). In a model for preventing and delaying acute colitis, clearance of RONS has been shown to reduce intestinal inflammation in mice by reducing colon damage, proinflammatory cytokine levels, the spleen index, and body weight. Intestinal mucosal healing can be promoted by HZn-TA nanoparticles, which can upregulate zonula occludens protein 1 (ZO-1) and claudin-1 expression. Based on the results of this study, HZn-TA nanoparticles were able to effectively treat IBD with minimal adverse effects by being biocompatible, multienzyme active, and capable of scavenging RONS. Therefore, we pioneered the application of HZn-TA nanoparticles for the treatment of IBD, which are capable of clearing RONS without significant adverse effects. Statement of significance➢ HZn-TA nanoparticles were successfully prepared and could be effectively used to treat IBD.➢ Intestinal mucosal healing can be promoted by HZn-TA nanoparticles, which can upregulate ZO-1 and claudin-1 expression.➢ HZn-TA nanoparticles were able to effectively treat IBD with minimal adverse effects by being biocompatible, multienzyme active, and capable of scavenging RONS.

GPR120/FFAR4 stimulation attenuates airway remodeling and suppresses IL-4- and IL-13-induced airway epithelial injury via inhibition of STAT6 and Akt

BackgroundAirway remodeling is associated with severity and treatment insensitivity in asthma. This study aimed to investigate the effects of G protein-coupled receptor 120 (GPR120) stimulation on alleviating allergic inflammation and remodeling of airway epithelium. Research design and methodsOvalbumin (OVA)-challenged BALB/c mice and type-2-cytokine (IL-4 and IL-13)-exposed 16HBE human bronchial epithelial cells were treated with GSK137647A, a selective GPR120 agonist. Markers of allergic inflammation and airway remodeling were determined. ResultsGSK137647A attenuated inflammation and mucus secretion in airway epithelium of OVA-challenged mice. Stimulation of GPR120 in 16HBE suppressed expression of asthma-associated cytokines and cytokine-induced expression of pathogenic mucin-MUC5AC. These effects were abolished by co-treatment with AH7614, a GPR120 antagonist. Moreover, GPR120 stimulation in 16HBE cells reduced expression of fibrotic markers including fibronectin protein and ACTA2 mRNA and inhibited epithelial barrier leakage induced by type-2 inflammation via rescuing expression of zonula occludens-1 protein. Furthermore, GPR120 stimulation prevented the cytokine-induced airway epithelial remodeling via suppression of STAT6 and Akt phosphorylation. ConclusionsOur findings suggest that GPR120 activation alleviates allergic inflammation and remodeling of airway epithelium partly through inhibition of STAT6 and Akt. GPR120 may represent a novel therapeutic target for diseases associated with remodeling of airway epithelium, including asthma.

β-sitosterol alleviates dextran sulfate sodium-induced experimental colitis via inhibition of NLRP3/Caspase-1/GSDMD-mediated pyroptosis.

Background: Inflammation-related NLRP3/Caspase-1/GSDMD-mediated pyroptosis is involved in the progression of ulcerative colitis (UC). β-sitosterol (SIT) was reported to have anti-inflammatory effects on experimental colitis, while the regulation of SIT on pyroptosis is unclear. Therefore, the present study aimed to define the protective and healing effects of SIT on dextran sulfate sodium (DSS)-induced experimental UC rats and human epithelial colorectal adenocarcinoma cells (Caco-2) and explore the underlying mechanisms that are responsible for its effects on NLRP3/Caspase-1/GSDMD-mediated pyroptosis in UC. Methods: UC model rats were established by oral 4% DSS. Following colitis injury, the animals received SIT (doses of 50, 100, and 200mg/kg) treatment for 2 weeks. For in vitro study, we exposed Caco-2-50mg/mL DSS with or without SIT (concentrations of 8 and 16μg/mL). Disease activity index (DAI) and histopathological injury were assessed in vivo. Activation proteins of nuclear factor kappa B (NF-κB) signaling axis, and tight junction-related proteins of zonula occludens-1 (ZO-1) and occludin were detected in colon tissues. TNF-α, IL-1β, and IL-18 in serum and cell supernatant were measured by enzyme-linked immunosorbent assay (ELISA). Changes in NLRP3/Caspase-1/GSDMD-mediated pyroptosis signaling pathway activation were analyzed both in tissues and cells. Results: Our findings suggested that SIT treatment attenuated the severity of 4% DSS-induced UC by protecting rats from weight and colon length loss, and macroscopic damage. SIT also reduced proinflammatory factors production (TNF-α, IL-1β, and IL-18) in serum and cell supernatant. Mechanistically, SIT downregulated the expression levels of pyroptosis-related proteins including Caspase-1, cleaved-Caspase-1, NLRP3, GSDMD, and GSDMD-N in colon tissues and Caco-2 cells. Further analysis indicated that SIT maintained the colonic barrier integrity by enhancing the protein expression of ZO-1 and occludin. Conclusion: We confirmed that SIT exerts protective and therapeutic effects on DSS-induced colitis injury by suppressing NLRP3/Caspase-1/GSDMD-mediated pyroptosis and inflammation response. These findings demonstrated that SIT could be a potential medication for UC treatment.

Bioconversion of feather waste into bioactive nutrients in water by Bacillus licheniformis WHU.

Feathers become hazardous pollutants when deposited directly into the environment. The rapid expansion of the poultry industry has significantly increased feather waste, necessitating the development of new ways to degrade and utilize feathers. This study investigated the ability of Bacillus licheniformis WHU to digest intact chicken feathers in water. The results indicated that yields of free amino acids, bioactive peptides, and keratin-derived nano-/micro-particles were improved in bacteria- versus purified keratinase-derived feather hydrolysate. Bacteria-derived feather hydrolysate supplementation induced health benefits in mice, including significantly increased intestinal villus height and zonula occludens-1 protein expression, as well as increased secretory immunoglobulin A levels in the intestinal mucosa and superoxide dismutase activity in serum. Additionally, feather hydrolysate supplementation modulated the mouse gut microbiota, reflected by increased relative abundance of probiotics such as Lactobacillus spp., decreased relative abundance of Proteobacteria at the phylum level and pathogens such as Staphylococcus spp., and increased Bacteroidota/Firmicutes ratio. This study developed a simple, cost-effective method to degrade feathers by B. licheniformis WHU digestion, yielding a hydrolysate that can be directly used as a bioactive nutrient resource. The study findings have applications in the livestock, poultry, and aquaculture industries, which have high demands for cheap protein. KEY POINTS: • Bacillus licheniformis could degrade intact feather in water. • The resulting feather hydrolysate shows prebiotic effects on mouse.

Tert-butylhydroquinone attenuates LPS-induced pyroptosis of IPEC-J2 cells via downregulating HMGB1/TLR4/NF-κB axis.

Inflammatory response induced by biological stress usually occurs in weaning piglets, it reduces the production performance of piglets and even causes death. Tert-butylhydroquinone (TBHQ) is a food additive that has the effect of anti-inflammation and anti-oxidation. However, there are few reports related to the protective mechanisms of TBHQ on lipopolysaccharide (LPS) induced injury in intestinal porcine epithelial (IPEC-J2) cells. Quantitative real-time polymerase chain reaction and western blot analysis, respectively, detected the mRNA levels and protein expressions related to pyroptosis, tight junction (TJ) protein and high-mobility group box 1/toll-like receptor 4/nuclear factor kappa-B (HMGB1/TLR4/NF-κB) axis. Localisation and expression of NOD-like receptor pyrin domain containing 3 (NLRP3), HMGB1 and P-NF-κB proteins detected by immunofluorescence. The results showed that TBHQ (12.5 and 25 μM) can increase cell activity and reduce intracellular lactate dehydrogenase (LDH) levels in a dose-dependent manner. LPS significantly decreases cell viability and increases the LDH level. However, pretreatment with TBHQ evidently increases cell viability and decreases the LDH level of IPEC-J2 cells. In addition, treatment with LPS decreased the mRNA level and protein expression of zonula occludens-1, occludin and claudin-1, and increased the mRNA level and protein expression of pyroptosis and HMGB1/TLR4/NF-κB axis. Interestingly, pretreatment with TBHQ increased the TJ protein expressions as well as decreased the mRNA level and protein expressions of pyroptosis and HMGB1/TLR4/NF-κB axis. Moreover, the results of immunofluorescence showed that TBHQ significantly reduced the expression of NLRP3, HMGB1 and P-NF-κB in LPS-induced injury of IPEC-J2 cells. Therefore, we come to the conclusion that TBHQ attenuates LPS-induced pyroptosis in IPEC-J2 cells through downregulation of the HMGB1/TLR4/NF-κB axis, TBHQ may become a potential feed additive for preventing inflammatory diarrhoea in piglets.

Main active components of Ilex rotunda Thunb. protect against ulcerative colitis by restoring the intestinal mucosal barrier and modulating the cytokine-cytokine interaction pathways

Ethnopharmacological relevanceIlex rotunda Thunb. (IR) is widely used for gastrointestinal diseases by Yao physician, and it has a better clinical curative effect on ulcerative colitis (UC). However, the main active components and mechanism of IR in the treatment of UC remain to be clarified. Aim of the studyTo investigate the main active components and mechanism of IR in the treatment of UC. Materials and methodsTen biological active components of IR were quantified by UPLC-MS/MS. In vitro, Caco2 cell monolayers were stimulated by lipopolysaccharide, and were treated with 10 biologically active components individually to investigate the protective role of the components of IR in mucosal barrier damage. In vivo, a mouse model of UC was induced by dextran sulfate sodium and administered with the candidate active components of IR. On day 8, the serum and colon tissue were collected for histological and molecular analysis to investigate the main active components and mechanism of IR. ResultsZiyuglycoside I, ziyuglycoside II, syringin, and pedunculoside in IR reduced phenol red transmission of the monolayer, and inhibited the protein expression of oncostatin M and oncostatin M receptor in Caco2 cells. Notably, ziyuglycoside II and syringin decreased the transepithelial electrical resistance of the monolayer, and promoted the protein expression of Occludin, Claudin-1 and zonula occludens-1 (ZO-1) in Caco2 cells. In vivo, ziyuglycoside II and syringin improved the symptoms of UC mice, including body weight, disease activity score, shortening of colon length, damaging of acidic mucus layer, histopathological changes, and protein expression of Occludin, Claudin-1, and ZO-1. Pedunculoside reduced the neutrophils and inflammatory response in the UC mice. Moreover, when the combination of ziyuglycoside II, syringin and pedunculoside was used for the treatment of UC, syringin and pedunculoside enhanced the therapeutic effect of ziyuglycoside II. Finally, RNA sequencing and RT-qPCR analysis revealed that ziyuglycoside II + syringin + pedunculoside and IR coregulated up to 42.7% of genes, and mainly reduced the overexpression of C-X-C motif ligand 1(CXCL1), oncostatin M receptor (OSMR), interleukin 1 receptor type I (IL1R1), tumor necrosis factor receptor superfamily member 9 (TNFRSF9), C-X-C motif chemokine 13 (CXCL13), oncostatin M (OSM), and interleukin 6 (IL-6) in the cytokine-cytokine interaction pathways. ConclusionsThe combination of ziyuglycoside II, syringin, and pedunculoside protects against UC by modulating the intestinal mucosal barrier and inhibiting the cytokine-cytokine interaction pathways, and the effect is relatively equivalent to that of the water extract of Ilex rotunda Thunb.

Effects of sevoflurane on lung epithelial permeability in experimental models of acute respiratory distress syndrome

BackgroundPreclinical studies in acute respiratory distress syndrome (ARDS) have suggested that inhaled sevoflurane may have lung-protective effects and clinical trials are ongoing to assess its impact on major clinical outcomes in patients with ARDS. However, the underlying mechanisms of these potential benefits are largely unknown. This investigation focused on the effects of sevoflurane on lung permeability changes after sterile injury and the possible associated mechanisms.MethodsTo investigate whether sevoflurane could decrease lung alveolar epithelial permeability through the Ras homolog family member A (RhoA)/phospho-Myosin Light Chain 2 (Ser19) (pMLC)/filamentous (F)-actin pathway and whether the receptor for advanced glycation end-products (RAGE) may mediate these effects. Lung permeability was assessed in RAGE−/− and littermate wild-type C57BL/6JRj mice on days 0, 1, 2, and 4 after acid injury, alone or followed by exposure at 1% sevoflurane. Cell permeability of mouse lung epithelial cells was assessed after treatment with cytomix (a mixture of TNFɑ, IL-1β, and IFNγ) and/or RAGE antagonist peptide (RAP), alone or followed by exposure at 1% sevoflurane. Levels of zonula occludens-1, E-cadherin, and pMLC were quantified, along with F-actin immunostaining, in both models. RhoA activity was assessed in vitro.ResultsIn mice after acid injury, sevoflurane was associated with better arterial oxygenation, decreased alveolar inflammation and histological damage, and non-significantly attenuated the increase in lung permeability. Preserved protein expression of zonula occludens-1 and less increase of pMLC and actin cytoskeletal rearrangement were observed in injured mice treated with sevoflurane. In vitro, sevoflurane markedly decreased electrical resistance and cytokine release of MLE-12 cells, which was associated with higher protein expression of zonula occludens-1. Improved oxygenation levels and attenuated increase in lung permeability and inflammatory response were observed in RAGE−/− mice compared to wild-type mice, but RAGE deletion did not influence the effects of sevoflurane on permeability indices after injury. However, the beneficial effect of sevoflurane previously observed in wild-type mice on day 1 after injury in terms of higher PaO2/FiO2 and decreased alveolar levels of cytokines was not found in RAGE−/− mice. In vitro, RAP alleviated some of the beneficial effects of sevoflurane on electrical resistance and cytoskeletal rearrangement, which was associated with decreased cytomix-induced RhoA activity.ConclusionsSevoflurane decreased injury and restored epithelial barrier function in two in vivo and in vitro models of sterile lung injury, which was associated with increased expression of junction proteins and decreased actin cytoskeletal rearrangement. In vitro findings suggest that sevoflurane may decrease lung epithelial permeability through the RhoA/pMLC/F-actin pathway.Graphical

Extracellular ATP accelerates cell death and decreases tight junction protein ZO-1 in hypoxic cochlear strial marginal cells in neonatal rats

In the cochlea, extracellular ATP (eATP) plays an important role in both physiological and pathological processes, but its role in the hypoxic cochlea remains unclear. The present study aims to investigate the relationship between eATP and hypoxic marginal cells (MCs) in the stria vascularis in cochlea. Combining various methodologies, we found that eATP accelerates cell death and decreases tight junction protein zonula occludens-1 (ZO-1) in hypoxic MCs. Flow cytometry and western blot analyses revealed an increase in apoptosis levels and suppression of autophagy, indicating that eATP causes additional cell death by increasing the apoptosis of hypoxic MCs. Given that autophagy inhibits apoptosis to protect MCs under hypoxia, apoptosis is probably enchanced by suppressing autophagy. Interleukin-33(IL-33)/suppression of tumorigenicity-2(ST-2)/matrix metalloprotein 9(MMP9) pathway activation was also observed during the process. Further experiments involving the use of additional IL-33 protein and an MMP9 inhibitor indicated that this pathway is responsible for the damage to the ZO-1 protein in hypoxic MCs. Our study revealed an adverse effect of eATP on the survival and ZO-1 protein expression of hypoxic MCs, as well as the underlying mechanism.

Protective Effect of Mesenchymal Stem Cell Transplantation on Intestinal Injury in Septic Mice and Its Mechanism

To explore the protective effect of placenta-derived mesenchymal stem cells (P-MSCs) transplantation on intestinal injury in septic mice and its mechanism. A total of 24 mice were randomly assigned to 3 groups, a sham operation group, a sepsis group that underwent cecal ligation and puncture (CLP) procedure, and a group that received CLP and P-MSCs treatment. Hereinafter, the three groups are referred to as the Sham group, the CLP group, and the CLP+P-MSCs group. For the mice in the Sham group, the abdomen was cut open and the cecum was exposed and then placed back in the abdomen. CLP was performed in the other two groups to establish the sepsis model. Mice in the Sham and the CLP groups received 0.1 mL of 0.9% NaCl injection in the tail vein 1 hour after operation, while mice in the CLP+P-MSCs group received 2×10 5 P-MSCs infusion 1 hour after operation. Intestinal and blood specimens were collected from the mice in each group 24 hours after P-MSCs transplantation. Hematoxylin and eosin (HE) staining of the intestinal tissue was performed for pathological evaluation. The serum concentrations of D-lactic acid, diamine oxidase (DAO), endotoxin, interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6, IL-10, and transforming growth factor (TGF)-β were determined by enzyme linked immunosorbent assay (ELISA). The gene expression of the relevant inflammatory factors in the small intestinal tissue was determined by real-time fluorescence polymerase chain reaction. The expression of zonula occludens protein-1 (ZO-1) and occludin protein in the intestine was determined by Western blot, the infiltration of intestinal macrophages was determined by immunohistochemical method, and the polarization of macrophages was determined by immunofluorescence. The exogenous transplantation of P-MSCs could form colonies in the injured intestines of septic mice. Compared with those of the CLP group, the intestinal injury of the CLP+P-MSCs group was significantly alleviated, the serum concentrations of D-lactic acid, DAO, endotoxin, IL-1β, IL-6, and TNF-α were significantly decreased ( P<0.05), while the serum concentrations of IL-10 and TGF-β were significantly increased ( P<0.05), the expression levels of IL-1 β, TNF-α and IL-6 genes in the intestinal tissue were significantly decreased ( P<0.05), while the expression levels of IL-10 and TGF-β genes were significantly increased ( P<0.05), and the expression of ZO-1 and occludin proteins in the intestine was also significantly increased ( P<0.05). In addition, the distribution of macrophages in the intestinal tissue of the CLP+P-MSCs group decreased significantly and the macrophages showed a tendency for M2 polarization. Exogenous transplantation of P-MSCs can significantly reduce inflammatory injury and improve the intestinal barrier function in septic mice with intestinal injury. Reduction in the infiltration of macrophages and promotion of the polarization of macrophages from M1 to M2 may be the mechanisms underlying the reduction of inflammation.

Hypoxia, but Not Normoxia, Reduces Effects of Resveratrol on Cisplatin Treatment in A2780 Ovarian Cancer Cells: A Challenge for Resveratrol Use in Anticancer Adjuvant Cisplatin Therapy

Natural compounds, such as resveratrol (Res), are currently used as adjuvants for anticancer therapies. To evaluate the effectiveness of Res for the treatment of ovarian cancer (OC), we screened the response of various OC cell lines to the combined treatment with cisplatin (CisPt) and Res. We identified A2780 cells as the most synergistically responding, thus optimal for further analysis. Because hypoxia is the hallmark of the solid tumor microenvironment, we compared the effects of Res alone and in combination with CisPt in hypoxia (pO2 = 1%) vs. normoxia (pO2 = 19%). Hypoxia caused an increase (43.2 vs. 5.0%) in apoptosis and necrosis (14.2 vs. 2.5%), reactive oxygen species production, pro-angiogenic HIF-1α (hypoxia-inducible factor-1α) and VEGF (vascular endothelial growth factor), cell migration, and downregulated the expression of ZO1 (zonula occludens-1) protein in comparison to normoxia. Res was not cytotoxic under hypoxia in contrast to normoxia. In normoxia, Res alone or CisPt+Res caused apoptosis via caspase-3 cleavage and BAX, while in hypoxia, it reduced the accumulation of A2780 cells in the G2/M phase. CisPt+Res increased levels of vimentin under normoxia and upregulated SNAI1 expression under hypoxia. Thus, various effects of Res or CisPt+Res on A2780 cells observed in normoxia are eliminated or diminished in hypoxia. These findings indicate the limitations in using Res as an adjuvant with CisPt therapy in OC.

PEDF Protects Endothelial Barrier Integrity during Acute Myocardial Infarction via 67LR.

Maintaining the integrity and protecting the stability of tight junctions in endothelial cells is a potential therapeutic strategy against myocardial ischaemia. Laminin receptors (67LR) are highly expressed on endothelial cell membranes and are associated with endothelial barrier function. Herein, we sought to demonstrate the direct effects of pigment epithelial-derived factor (PEDF) on tight junctions between endothelial cells via 67LR during acute myocardial infarction (AMI) and elucidate its underlying mechanisms. We detected that PEDF directly increased the level of the tight junction protein zonula occludens protein 1 (ZO-1) after overexpression in vitro and in vivo using Western blotting. Evans Blue/TTC staining showed that PEDF significantly reduced the size of the infarcted myocardium. Immunofluorescence and the transwell cellular experiments suggested that PEDF significantly upregulated PI3K-AKT permeability and the distribution of ZO-1 between endothelial cells under OGD conditions. Interestingly, PEDF significantly upregulated the phosphorylation levels of PI3K-AKT-mTOR under oxygen and glucose deprivation conditions but had no significant effects on the total protein expression. The protective effect of PEDF on ZO-1 was significantly inhibited following the inhibition of PI3K-AKT-mTOR. The activation of phosphorylation of PI3K-AKT-mTOR by PEDF was blocked after silencing 67LR, as were the protective effects of PEDF on ZO-1. Therefore, we have reason to believe that PEDF increased ZO-1 expression through the 67LR-dependent PI3K-AKT-mTOR signaling pathway, thus maintaining tight junction stability and protecting cardiac function.

Ameliorative effect of ginsenoside Rg1 on dextran sulfate sodium-induced colitis: involvement of intestinal barrier remodeling in mice.

Ginsenoside Rg1, a major bioactive ingredient of Panax notoginseng, has been shown to reduce gut inflammation and ameliorate experimental colitis in mice. However, it is not yet known whether it affects the intestinal barrier injury of colitis. This study explored the effect of ginsenoside Rg1 on intestinal barrier injury in dextran sulfate sodium (DSS)-induced colitis mice through an ultrastructure observation of the colonic mucosa and analysis of the expression of colonic cytoplasmatic zonula occludens-1 (ZO-1) protein. Treatment with ginsenoside Rg1, especially high-dose use, significantly ameliorated colonic histopathologic features and the severity of the colitis and reduced colonic tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ) levels and increase IL-4 levels in a mouse model of DSS-induced colitis. Its observed efficacy was comparable to that of 5-Aminosalicylic acid (5-ASA), a first-line therapeutic agent for ulcerative colitis. Notably, ginsenoside Rg1 administration was shown to up-regulate the expression of colonic ZO-1 protein, and it repaired the intestinal barrier structure in DSS-induced colitis mice. Taken together, our findings demonstrated that ginsenoside Rg1 treatment can significantly ameliorate the severity of DSS-induced colitis in mice, which involves intestinal barrier structure remodeling through lowering the levels of the colonic pro-inflammatory cytokines TNF-α and IFN-γ and increasing the anti-inflammatory cytokine IL-4. These results suggest the potential therapeutic use of ginsenoside Rg1 as a promising approach for the treatment of inflammatory bowel disease (IBD).

Usnea improves high-fat diet- and vitamin D3-induced atherosclerosis in rats by remodeling intestinal flora homeostasis.

Background: Usnea has various pharmacological properties, including anti-inflammatory, antitumor, antioxidant, antiviral, and cardiovasculoprotective effects. Aim of the study: To investigate the potential mechanisms underlying the anti-atherosclerosis (AS) activity of Usnea ethanol extract (UEE) via the regulation of intestinal flora. Materials and Methods: The chemical composition of UEE was determined using ultra-performance liquid chromatography with quadrupole exactive orbitrap mass spectrometry (UPLC-Q-EOMS). Thirty-six male Sprague-Dawley rats were divided into six groups. A high-fat diet and intraperitoneal vitamin D3 injections were used to establish a rat model of AS. After 4weeks of treatment with UEE, hematoxylin-eosin staining was performed to evaluate the pathomorphology of the aorta, liver, and colon. The composition and diversity of the rat intestinal flora were determined using high-throughput 16S rRNA sequencing. Enzyme-linked immunosorbent assays were used to measure the levels of plasma trimethylamine oxide (TMAO), serum bile acid (BA), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). The protein expression of cholesterol 7α-hydroxylase (CYP7A1) and flavin monooxygenase 3 (FMO3) in the liver and zonula occludens-1 (ZO-1) and occludin in colon tissue was detected via western blotting. Results: Forty-four compounds were identified in UEE. In the rat model of AS, UEE significantly prevented calcium deposition; decreased the serum levels of TC, TG, LDL-C, LPS, TNF-α, and IL-6; and increased the serum level of HDL-C. Additionally, all UEE dosages decreased the relative abundance of Verrucomicrobiota while increased that of Bacteroidetes. FMO3 protein expression and TMAO levels decreased, whereas CYP7A1 protein expression and BA levels increased. The absorption of intestinal-derived LPS was minimized. Furthermore, the protein expression of ZO-1 and occludin was upregulated. Conclusion: UEE ameliorated AS. The underlying mechanism was the reversal of imbalances in the intestinal flora by Usnea, thereby inhibiting calcium deposition, abnormal lipid metabolism, and inflammatory response.

Intestinal mucosal barrier in functional constipation: Dose it change?

BACKGROUNDThe 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).AIMTo investigate the intestinal mucosal barrier in FC, including the mucus barrier, intercellular junctions, mucosal immunity and gut permeability.METHODSForty 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.RESULTSCompared 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/mm2; FC, 22.70 ± 11.38/mm2; 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.CONCLUSIONThe 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.