Effects of pro-inflammatory cytokines, lipopolysaccharide and COX-2 mediators on human colonic neuromuscular function and epithelial permeability

N-Acetylglucosamine and its dimer ameliorate inflammation in murine colitis by strengthening the gut barrier function

Ulcerative colitis (UC) is a chronic gastrointestinal disease whose incidence is increasing rapidly worldwide. Anti-inflammatory medications, including 5-aminosalicylic acid (5-ASA), corticosteroids, and immunosuppressants, are used for its treatment; however, new alternatives would be required due to the serious side effects of some of these medications. N-Acetylglucosamine (NAG) is an amino sugar composed of mucin that is secreted by intestinal epithelial cells. It is also used to promote the growth of intestinal bacteria. The current study aimed to determine the efficacy of NAG against dextran sulfate sodium (DSS)-induced chronic colitis and elucidate its mechanism of action. Mice were randomly divided into control, DSS, 0.1% sulfasalazine, 0.1% NAG, 0.3% NAG, and 0.3% NAG-dimer (NAG-D) groups, and results showed that colitis-induced body weight loss, disease activity, colonic tissue damage, colon length shortening, and the loss of mucin-secreting area were significantly improved in the NAG-D group. The intestinal permeability indicator, serum CD 14 level, and expression of the tight junction protein, occludin, were both improved in the 0.3% NAG group. Inflammatory biomarkers, including GATA3, IFN-γ, p-IκBα, COX2, TGF-β1, and Smad7, were significantly lower in the 0.3% NAG and NAG-D groups than in the DSS group. The intestinal microbial composition was most significantly altered in the 0.3% NAG group, showing decreased ratios of pathogenic bacteria, such as Betaproteobacteria, especially Burkholderiales. The results overall suggested that NAG or NAG-D supplementation can alleviate inflammation by strengthening the intestinal barrier function and maintaining gut microbiota homeostasis in a DSS-induced colitis mouse model.

The Role of Inflammatory Mediators in the Development of Gastrointestinal Motility Disorders

Feeding intolerance and the development of ileus is a common complication affecting critically ill, surgical, and trauma patients, resulting in prolonged intensive care unit and hospital stays, increased infectious complications, a higher rate of hospital readmission, and higher medical care costs. Medical treatment for ileus is ineffective and many of the available prokinetic drugs have serious side effects that limit their use. Despite the large number of patients affected and the consequences of ileus, little progress has been made in identifying new drug targets for the treatment of ileus. Inflammatory mediators play a critical role in the development of ileus, but surprisingly little is known about the direct effects of inflammatory mediators on cells of the gastrointestinal tract, and many of the studies are conflicting. Understanding the effects of inflammatory cytokines/chemokines on the development of ileus will facilitate the early identification of patients who will develop ileus and the identification of new drug targets to treat ileus. Thus, herein, we review the published literature concerning the effects of inflammatory mediators on gastrointestinal motility.

Bisphenol S exposure induces intestinal inflammation: An integrated metabolomic and transcriptomic study

As a typical substitute for bisphenol A (BPA), bisphenol S (BPS) is raising concerns due to the potential adverse effects on human health. Limit evidence is available to understand the toxicity of BPS to the digestive system, especially for intestine. In this study, we aimed to investigate the potential effects and underlying mechanisms of BPS exposure on human colon mucosal epithelial cells (NCM460). Our results showed that BPS exposure significantly increased the production of pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ) and interleukin-17A (IL-17A). The tight junctions of the cells has been destroyed by BPS exposure, which was characterized by a down-regulation of the tight junction proteins (Claudin1 and zonula occluden 1 (ZO1)). A multi-omics study explored the underlying mechanisms based on the metabolomic and transcriptomic responses. A variety of neurotransmitters increased significantly after exposure to BPS. The top enriched pathway was "glutamatergic synapse", which was activated by BPS exposure, resulting in the up-regulation of l-glutamine. Links were observed among the altered metabolites, genes and cytokines. Our results indicate that exposure to BPS may disturb the balance of gut-brain axis, leading to the production of inflammatory cytokines and the destruction of tight junction in NCM460 cells. It provides new clue for the development of intestinal inflammation in terms of the environmental pollutants.

The Anti-Inflammatory Effect of Bovine Bone-Gelatin-Derived Peptides in LPS-Induced RAW264.7 Macrophages Cells and Dextran Sulfate Sodium-Induced C57BL/6 Mice

The bioactive peptides hydrolyzed from bone collagen have been found to possess health-promoting effects by regulating chronic diseases such as arthritis and hypertension. In the current study, the anti-inflammatory effect of bovine bone gelatin peptides (GP) was evaluated in 264.7 macrophages cells and followed by animal trials to investigate their interference on inflammatory cytokines and gut microbiota compositions in dextran sodium sulfate (DSS)-induced C57BL/6 mice. The GP was demonstrated to alleviate the extra secretion of interleukin-6 (IL-6), nitric oxide (NO) and tumor necrosis factor-α(TNF-α) in lipopolysaccharide (LPS)-induced RAW264.7 cells. In DSS-induced colitis mice, the gavage of GP was demonstrated to ameliorate the IBD symptoms of weight loss, hematochezia and inflammatory infiltration in intestinal tissues. In serum, the proinflammatory cytokines (TNF-α,IL-6, MCP-1, IL-1β) were suppressed along with the decreasing effect on toll-like receptor 4 and cyclooxygenase-2 by GP treatment. In the analysis of gut microbiota, the GP was checked to modulate the abundance of Akkermansia, Parasutterella, Peptococcus, Bifidobacterium and Saccharibacteria. The above results imply that GP could attenuate DSS-induced colitis by suppressing the inflammatory cytokines and regulating the gut microbiota.

Protective efficacy of fish oil nanoemulsion against non-typhoidal Salmonella mediated mucosal inflammation and loss of barrier function

Non-typhoidal Salmonella serotypes are well-adapted to utilize the inflammation for colonization in mammalian gut mucosa and bring down the integrity of the epithelial barrier in mammalian intestine. The present study...

Canna x generalis L.H. Bailey rhizome extract ameliorates dextran sulfate sodium-induced colitis via modulating intestinal mucosal dysfunction, oxidative stress, inflammation, and TLR4/ NF-ҡB and NLRP3 inflammasome pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Genus Canna is used in folk medicine as demulcent, diaphoretic, antipyretic, mild laxative and in gastrointestinal upsets therapy. Canna x generalis (CG) L.H. Bailey is traditionally used as anti-inflammatory, analgesic and antipyretic. Besides, CG is used in Ayurvedic medicines' preparations and in the treatment of boils, wounds, and abscess. Nevertheless, its anti-inflammatory effects against ulcerative colitis (UC) are not yet investigated.

AIM

This study aimed to investigate the phytoconstituents of CG rhizome ethanol extract (CGE). Additionally, we aimed to comparatively evaluate its therapeutic effects and underlying mechanisms against the reference drug "sulphasalazine (SAS)" in dextran sodium sulfate (DSS)-induced UC in mice.

MATERIAL AND METHODS

Metabolic profiling of CG rhizomes was performed via UHPLC/qTOF-HRMS; the total phenolic, flavonoid and steroid contents were determined, and the main phytoconstituents were isolated and identified. Next, DSS-induced (4%) acute UC was established in C57BL/6 mice. DSS-induced mice were administered either CGE (100 and 200 mg/kg) or SAS (200 mg/kg) for 7 days. Body weight, colon length, disease activity index (DAI) and histopathological alterations in colon tissues were examined. Colon levels of oxidative stress (GSH, MDA, SOD and catalase) and pro-inflammatory [Myeloperoxidase (MPO), nitric oxide (NO), IL-1β, IL-12, TNF-α, and INF-γ] markers were colourimetrically determined. Serum levels of lipopolysaccharide (LPS) and relative mRNA expressions of occludin, TLR4 and ASC (Apoptosis-Associated Speck-Like Protein Containing CARD) using RT-PCR were measured. Protein levels of NLRP3 inflammasome and cleaved caspase-1 were determined by Western blot. Furthermore, immunohistochemical examinations of caspase-3, NF-ҡB and claudin-1 were performed.

RESULTS

Major identified constituents of CGE were flavonoids, phenolic acids, phytosterols, beside five isolated phytoconstituents (β-sitosterol, triacontanol fatty alcohol, β-sitosterol-3-O-β-glucoside, rosmarinic acid, 6-O-p-coumaroyl-β-D-fructofuranosyl α-D-glucopyranoside). The percentage of the phenolic, flavonoid and steroid contents in CGE were 20.55, 6.74 and 98.09 μg of gallic acid, quercetin and β-sitosterol equivalents/mg extract, respectively. In DSS-induced mice, CGE treatment ameliorated DAI, body weight loss and colon shortening. CGE attenuated the DSS-induced colonic histopathological alternations, inflammatory cell infiltration and histological scores. CGE elevated GSH, SOD and catalase levels, and suppressed MDA, pro-inflammatory mediators (MPO and NO) as well as cytokines levels in colonic tissues. Moreover, CGE downregulated LPS/TLR4 signaling, caspase-3 and NF-ҡB expressions. CGE treatment inhibited NLRP3 signaling pathway as indicated by the suppression of the protein expression of NLRP3 and cleaved caspase-1, and the ASC mRNA expression in colonic tissues. Additionally, CGE restored tight junction proteins' (occludin and claudin-1) expressions.

CONCLUSION

Our findings provided evidence for the therapeutic potential of CGE against UC. CGE restored intestinal mucosal barrier's integrity, mitigated oxidative stress, inflammatory cascade, as well as NF-ҡB/TLR4 and NLRP3 pathways activation in colonic tissues. Notably, CGE in a dose of 200 mg/kg was more effective in ameliorating DSS-induced UC as compared to SAS at the same dose.

Effect of roxithromycin on contractile activity of gastrointestinal smooth muscles in colitic rats

OBJECTIVES

Roxithromycin, a macrolide antibiotic, has been shown to ameliorate acetic acid induced colitis in rats by suppressing inflammation and oxidative stress. The aim of this study was to evaluate the effect of roxithromycin on small intestinal transit and cholinergic responsiveness of the colonic smooth muscles of colitic rats.

METHODS

Colitis was induced in rats by acetic acid and the small intestinal transit was determined by measuring the distance traversed by charcoal meal from the gastro-duodenal junction in 1 h. The test drug roxithromycin, reference drug mesalazine and anti-inflammatory drug diclofenac were administered orally before inducing colitis and their effect on intestinal transit was compared with colitic control group. The effect on cholinergic responsiveness of colonic smooth muscles was evaluated in vitro by plotting a dose-response curve using different concentrations of acetylcholine. The concentration producing 50% of maximal response (EC₅₀) was calculated for all the treatment groups.

RESULTS

The small intestinal transit was enhanced in colitic rats as compared to normal rats (86.00 ± 1.36 vs. 57.00 ± 1.34 cm; p<0.001). Like mesalazine, roxithromycin normalized intestinal transit while diclofenac was ineffective. The results of in vitro experiment show that colitis increased cholinergic responsiveness of the colonic smooth muscles that was not affected by roxithromycin and mesalazine while diclofenac significantly decreased it.

CONCLUSIONS

This study shows that like mesalazine, roxithromycin affords protection in colitis mainly by normalizing propulsive movement of the small intestine than by affecting cholinergic responsiveness of the colonic smooth muscles.

Anti-Inflammatory and Chemopreventive Effects of Bryophyllum pinnatum (Lamarck) Leaf Extract in Experimental Colitis Models in Rodents

Inflammatory bowel diseases, mainly ulcerative colitis and Crohn's disease are characterized by chronic inflammation in the intestine. Currently several therapeutic strategies available to treat inflammatory bowel diseases. Though, most treatments can be associated with serious adverse effects what justifies the search for new treatments. In this sense, we highlight the interest in herbal products rich in bioactive compounds which immunomodulatory and antioxidant properties as is the case of Bryophyllum pinnatum (Crassulaceae). This plant is used in traditional medicine in Brazil for treating inflammatory diseases. We hypothesized that hydroethanolic B. pinnatum leaf extract has intestinal anti-inflammatory effects on two experimental colitis models: 2.4-dinitrobenzene sulfonic acid (DNBS) in rats, and dextran sulfate sodium (DSS) in mice. Ultra-fast liquid chromatography method used for the quantification of the main compounds indicated good linearity, specificity, selectivity, precision, robustness and accuracy. The major flavonoids (mg/g of the extract) quantified were: quercetin 3-O-α-L-arabinopyranosyl-(1→2)-α-L-rhamnopyranoside (35.56 ± 0.086 mg/g), kaempferol 3-O-α-L-arabinopyranosyl-(1→2)-α-L-rhamnopyranoside (4.66 ± 0.076 mg/g) and quercetin-3-O-rhamnopyranoside (4.56 ± 0.026 mg/g). The results obtained in the DNBS and DSS models indicate that extract has both chemopreventive and anti-inflammatory effects, observing a significant reduction in the disease activity index score, and less macroscopic and microscopic damage. The extract promoted downregulation of Toll-like receptor and kappa B p65 nuclear factor gene expression, leading to a reduction in pro-inflammatory and oxidative mediators, chemokines, and cell adhesion molecules. This immunomodulatory property was proposed that one of the possible action mechanisms of extract. An improvement in intestinal damage was also associated with a reduction in oxidative stress and infiltration of leukocytes, as evidenced by the reduction in malonaldialdehyde and myeloperoxidase activity and increase in total glutathione in the colonic tissue. Moreover, the extract improved the cytoarchitecture of the colonic tissue and the integrity of the intestinal epithelial barrier by restoring the expression of the proteins associated with mucosa protection. In view of the beneficial effects showed by the B. pinnatum leaf extract in preclinical rodent models of colitis there is the potential to conduct some future clinical studies to ensure safe and effective development of a phytotherapeutic treatment for human inflammatory bowel diseases.

Palmitic Acid Affects Intestinal Epithelial Barrier Integrity and Permeability In Vitro

Palmitic acid (PA), a long-chain saturated fatty acid, might activate innate immune cells. PA plays a role in chronic liver disease, diabetes and Crohn’s disease, all of which are associated with impaired intestinal permeability. We investigated the effect of PA, at physiological postprandial intestinal concentrations, on gut epithelium as compared to lipopolysaccharide (LPS) and ethanol, using an in vitro gut model, the human intestinal epithelial cell line Caco-2 grown on transwell inserts. Cytotoxicity and oxidative stress were evaluated; epithelial barrier integrity was investigated by measuring the paracellular flux of fluorescein, and through RT-qPCR and immunofluorescence of tight junction (TJ) and adherens junction (AJ) mRNAs and proteins, respectively. In PA-exposed Caco-2 monolayers, cytotoxicity and oxidative stress were not detected. A significant increase in fluorescein flux was observed in PA-treated monolayers, after 90 min and up to 360 min, whereas with LPS and ethanol, this was only observed at later time-points. Gene expression and immunofluorescence analysis showed TJ and AJ alterations only in PA-exposed monolayers. In conclusion, PA affected intestinal permeability without inducing cytotoxicity or oxidative stress. This effect seemed to be faster and stronger than those with LPS and ethanol. Thus, we hypothesized that PA, besides having an immunomodulatory effect, might play a role in inflammatory and functional intestinal disorders in which the intestinal permeability is altered.

Fushen Granule, A Traditional Chinese Medicine, ameliorates intestinal mucosal dysfunction in peritoneal dialysis rat model by regulating p38MAPK signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Fushen Granule (FSG) is a Chinese medicinal formular prepared in hospital to treat intestinal mucosal dysfunction induced by peritoneal dialysis (PD). However, the mechanisms of this formular has not been studied yet.

AIM OF THE STUDY

The present study was designed to investigate the effect of FSG against intestinal dysfunction during PD treatment and explore the potential mechanisms using a rat PD model.

METHODS AND METHODS

In the present study, the effect of FSG on improving intestinal mucosal architecture injury was intuitively shown by hematoxylin-eosin staining, the serum levels of DAO and D-lactate were measured to evaluate the intestinal permeability by the DAO Assay Kit and D-Lactic Acid ELISA Kit. The expression of the intestinal mucosal barrier related inflammation factor by real-time PCR. The main effective constituents of FSG were characterized by UPLC/Q-TOF analysis, and the targets and pathways of the constituents were predicted via TCMSP database and IPA. the activation of p38MAPK signaling pathway by western blotting.

RESULTS

HE staining results showed that FSG protected against intestinal mucosal injury in pathology in PD rats. FSG decreased the intestinal mucosal permeability by increasing the transepithelial electrical resistance (TER) level and decreasing the intestinal clearance of fluorescein-isothiocyanate dextran (FD4) and the level of D-lactate and diamine oxidase (DAO). FSG significantly decreased the expression of ICAM-1, IL-1β, iNOS and TNF-α, and further inhibited the activation of p38MAPK signaling pathway via down-regulating the expression of P-p38MAPK and up-regulating the expression of DUSP1, occludin, and ZO-1.

CONCLUSION

This study demonstrates that FSG ameliorated intestinal mucosal dysfunction in PD by decreasing expression of pro-inflammatory cytokines and inhibiting the activation of p38MAPK signaling pathway. The results provide a promising basis for the alternative medicine treatment of intestinal mucosal dysfunction in PD.

Comparison of the Effects and Inhibitory Pathways of the Constituents from Gynostemma pentaphyllum against LPS-Induced Inflammatory Response

Saponins, the primary phytochemicals contributing to the health properties of G. pentaphyllum were frequently studied. However, compounds responsible for its bioactivities were still poorly understood. The saponin-rich fraction (GPMS), 3- O-[2G-( E)-Coumaroyl-3G- O-β-d-glucosyl-3R- O-β-d-glucosylrutinoside] (KCGG), gypenoside XLVI and gypenoside L were obtained by purification of G. pentaphyllum. The compounds were examined and compared with GPMS for their inhibitory effects on LPS-induced nitric oxide (NO) production. GPMS and KCGG differed in their inhibitory capacities against pro-inflammatory cytokines secretion. GPMS exhibited strong inhibition on inducible nitric oxide synthase (iNOS) and interleukin-6 (IL-6) mRNA expression but weak inhibition on tumor necrosis factor-α (TNF-α) and interleukin-1β mRNA expression. KCGG was better at inhibiting iNOS, IL-6, TNF-α, and cyclooxygenase-2 (COX-2) mRNA expression. GPMS showed similar inhibitory potency on mitogen-activated protein kinase phosphorylation and nuclear factor-κB (NF-κB) activation, as evidenced by their regulatory effects on LPS-induced P65 phosphorylation, NF-κB nuclear translocation, IκBα phosphorylation and degradation, IκKα/β phosphorylation, c-Jun N-terminal kinase phosphorylation, P38 phosphorylation, and COX-2 expression. KCGG was more powerful in inhibiting the NF-κB pathway, suggesting that KCGG might be used in the management of inflammatory-associated diseases in which NF-κB played pivotal roles. Furthermore, KCGG might be mainly responsible for the predominant effects of GPMS.

Colonic migrating motor complexes are inhibited in acute tri-nitro benzene sulphonic acid colitis

Background

Inflammatory Bowel Disease (IBD) is characterized by overt inflammation of the intestine and is typically accompanied by symptoms of bloody diarrhea, abdominal pain and cramping. The Colonic Migrating Motor Complex (CMMC) directs the movement of colonic luminal contents over long distances. The tri-nitrobenzene sulphonic acid (TNBS) model of colitis causes inflammatory damage to enteric nerves, however it remains to be determined whether these changes translate to functional outcomes in CMMC activity. We aimed to visualize innate immune cell infiltration into the colon using two-photon laser scanning intra-vital microscopy, and to determine whether CMMC activity is altered in the tri-nitro benzene sulphonic (TNBS) model of colitis.

Methods

Epithelial barrier permeability was compared between TNBS treated and healthy control mice in-vitro and in-vivo. Innate immune activation was determined by ELISA, flow cytometry and by 2-photon intravital microscopy. The effects of TNBS treatment and IL-1β on CMMC function were determined using a specialized organ bath.

Results

TNBS colitis increased epithelial barrier permeability in-vitro and in-vivo. Colonic IL-1β concentrations, colonic and systemic CD11b+ cell infiltration, and the number of migrating CD11b+ cells on colonic blood vessels were all increased in TNBS treated mice relative to controls. CMMC frequency and amplitude were inhibited in the distal and mid colon of TNBS treated mice. CMMC activity was not altered by superfusion with IL-1β.

Conclusions

TNBS colitis damages the epithelial barrier and increases innate immune cell activation in the colon and systemically. Innate cell migration into the colon is readily identifiable by two-photon intra-vital microscopy. CMMC are inhibited by inflammation, but this is not due to direct effects of IL-1β.

Update on intestinal microbiota in Crohn's disease 2017: Mechanisms, clinical application, adverse reactions, and outlook

The pathogenesis of Crohn's disease (CD) is complex, and it is thought to be associated with the environment, immune, hereditary, microbe, and other factors. If the balance between the host and the intestinal microbes in CD patients was broken, immune-inflammatory response of susceptible individuals might be triggered. Probiotics could improve the intestinal microbial flora balance and treat human effectively. There are several new mechanisms that might explain the role of probiotics. Fecal microbiota transplantation (FMT) is becoming more and more attractive in treating a large amount of digestive system diseases that are related to the dysbiosis of intestinal microbiota. FMT has been widely used in recurrent Clostridium difficile infection. More and more attention has been paid on the clinical application of FMT in CD, while the exact mechanism is still a mystery. So in this review, we explore the mechanism, clinical application, and adverse reactions of intestinal microbiota in CD so that we can use the tool to cure more diseases. Enteric microbiota leads to new therapeutic strategies for CD.

Intestinal anti-inflammatory effects of goat whey on DNBS-induced colitis in mice

This study evaluated the intestinal anti-inflammatory effects of goat whey in a mouse model of colitis induced by 2,4-dinitrobenzenesulfonic acid that resembles human IBD. At a concentration of 4 g/kg/day, the goat whey improved the symptoms of intestinal inflammation, namely by decreasing the disease activity index, colonic weight/length, and leukocyte infiltration. Moreover, goat whey inhibited NF-κB p65 and p38 MAPK signaling pathways and consequently down-regulated the gene expression of various proinflammatory markers such as IL-1β, IL-6, IL-17, TNF-α, iNOS, MMP-9, ICAM-1. Also, goat whey increased the expression of proteins such as mucins, occludin proteins and cytokine signalling suppressors. The immunomodulatory properties of goat whey were also evaluated in vitro using the murine macrophage cell line Raw 264 and CMT-93 cells derived from mouse rectum carcinomas. The results revealed the ability of goat whey to inhibit the production of NO and reduce IL-6 production in LPS-stimulated cells. In conclusion, goat whey exhibited anti-inflammatory effects in the DNBS model of intestinal inflammation, and these observations were confirmed by its immunomodulatory properties in vitro. Together, our results indicate that goat whey could have applications for the treatment of IBD.