Altered permeability in inflammatory bowel disease: pathophysiology and clinical implications

Evaluation of the efficacy of probiotic VSL#3 and synbiotic VSL#3 and yacon-based product in reducing oxidative stress and intestinal permeability in mice induced to colorectal carcinogenesis

The objective of the present study was to evaluate the effect of probiotic VSL#3 isolated or associated with a yacon-based product (synbiotic) on oxidative stress modulation and intestinal permeability in an experimental model of colorectal carcinogenesis. Forty-five C57BL/6J mice were divided into three groups: control (standard diet AIN-93 M); probiotic (standard diet AIN-93 M and multispecies probiotic VSL#3, 2.25 × 10⁹ CFU), and synbiotic (standard diet AIN-93 M with yacon-based product, 6% fructooligosaccharides and inulin, and probiotic VSL#3, 2.25 × 10⁹ CFU). The experimental diets were provided for 13 weeks. The probiotic and the yacon-based product showed antioxidant activity, with the percentage of DPPH radical scavenging equal to 69.7 ± 0.4% and 74.3 ± 0.1%, respectively. These findings contributed to reduce hepatic oxidative stress: the control group showed higher concentration of malondialdehyde (1.8-fold, p = 0.007 and 1.5-fold, p = 0.035) and carbonylated protein (2-fold, p = 0.008 and 5.6-fold, p = 0.000) compared to the probiotic and synbiotic groups, respectively. Catalase enzyme activity increased 1.43-fold (p = 0.014) in synbiotic group. The crypt depth increased 1.2-fold and 1.4-fold with the use of probiotic and synbiotic, respectively, compared to the control diet (p = 0.000). These findings corroborate the reduction in intestinal permeability in the probiotic and synbiotic groups, as measured by the percentage of urinary lactulose excretion (CON: 0.93 ± 0.62% × PRO: 0.44 ± 0.05%, p = 0.048; and CON: 0.93 ± 0.62% × SYN: 0.41 ± 0.12%, p = 0.043). In conclusion, the probiotic and synbiotic showed antioxidant activity, which contributed to the reduction of oxidative stress markers. In addition, they protected the mucosa from damage caused by chemical carcinogen and reduced intestinal permeability. PRACTICAL APPLICATION: The relationship between intestinal health and the occurrence of various organic disorders has been demonstrated in many studies. The use of probiotics and prebiotics is currently one of the main targets for modulation of intestinal health. We demonstrated that the use of a commercial mix of probiotic bacteria (VSL#3) isolated or associated with a yacon-based prebiotic, rich in fructooligosaccharides and inulin, is able to reduce the oxidative stress and intestinal permeability in a colorectal carcinogenesis model. These compounds have great potential to be used as a food supplement, or as ingredients in the development of food products.

Mutation spectrum of NOD2 reveals recessive inheritance as a main driver of Early Onset Crohn's Disease

Inflammatory bowel disease (IBD), clinically defined as Crohn’s disease (CD), ulcerative colitis (UC), or IBD-unclassified, results in chronic inflammation of the gastrointestinal tract in genetically susceptible hosts. Pediatric onset IBD represents ≥ 25% of all IBD diagnoses and often presents with intestinal stricturing, perianal disease, and failed response to conventional treatments. NOD2 was the first and is the most replicated locus associated with adult IBD, to date. However, its role in pediatric onset IBD is not well understood. We performed whole-exome sequencing on a cohort of 1,183 patients with pediatric onset IBD (ages 0–18.5 years). We identified 92 probands with biallelic rare and low frequency NOD2 variants accounting for approximately 8% of our cohort, suggesting a Mendelian inheritance pattern of disease. Additionally, we investigated the contribution of recessive inheritance of NOD2 alleles in adult IBD patients from a large clinical population cohort. We found that recessive inheritance of NOD2 variants explains ~ 7% of cases in this adult IBD cohort, including ~ 10% of CD cases, confirming the observations from our pediatric IBD cohort. Exploration of EHR data showed that several of these adult IBD patients obtained their initial IBD diagnosis before 18 years of age, consistent with early onset disease. While it has been previously reported that carriers of more than one NOD2 risk alleles have increased susceptibility to Crohn’s Disease (CD), our data formally demonstrate that recessive inheritance of NOD2 alleles is a mechanistic driver of early onset IBD, specifically CD, likely due to loss of NOD2 protein function. Collectively, our findings show that recessive inheritance of rare and low frequency deleterious NOD2 variants account for 7–10% of CD cases and implicate NOD2 as a Mendelian disease gene for early onset Crohn’s Disease.

Linking bacterial enterotoxins and alpha defensin 5 expansion in the Crohn's colitis: A new insight into the etiopathogenetic and differentiation triggers driving colonic inflammatory bowel disease

Evidence link bacterial enterotoxins to apparent crypt-cell like cells (CCLCs), and Alpha Defensin 5 (DEFA5) expansion in the colonic mucosa of Crohn's colitis disease (CC) patients. These areas of ectopic ileal metaplasia, positive for Paneth cell (PC) markers are consistent with diagnosis of CC. Retrospectively, we: 1. Identified 21 patients with indeterminate colitis (IC) between 2000-2007 and were reevaluation their final clinical diagnosis in 2014 after a followed-up for mean 8.7±3.7 (range, 4-14) years. Their initial biopsies were analyzed by DEFA5 bioassay. 2. Differentiated ulcer-associated cell lineage (UACL) analysis by immunohistochemistry (IHC) of the CC patients, stained for Mucin 6 (MUC6) and DEFA5. 3. Treated human immortalized colonic epithelial cells (NCM460) and colonoids with pure DEFA5 on the secretion of signatures after 24hr. The control colonoids were not treated. 4. Treated colonoids with/without enterotoxins for 14 days and the spent medium were collected and determined by quantitative expression of DEFA5, CCLCs and other biologic signatures. The experiments were repeated twice. Three statistical methods were used: (i) Univariate analysis; (ii) LASSO; and (iii) Elastic net. DEFA5 bioassay discriminated CC and ulcerative colitis (UC) in a cohort of IC patients with accuracy. A fit logistic model with group CC and UC as the outcome and the DEFA5 as independent variable differentiator with a positive predictive value of 96 percent. IHC staining of CC for MUC6 and DEFA5 stained in different locations indicating that DEFA5 is not co-expressed in UACL and is therefore NOT the genesis of CC, rather a secretagogue for specific signature(s) that underlie the distinct crypt pathobiology of CC. Notably, we observed expansion of signatures after DEFA5 treatment on NCM460 and colonoids cells expressed at different times, intervals, and intensity. These factors are key stem cell niche regulators leading to DEFA5 secreting CCLCs differentiation 'the colonic ectopy ileal metaplasia formation' conspicuously of pathogenic importance in CC.

Immune System Investigation Using Parasitic Helminths

Coevolutionary adaptation between humans and helminths has developed a finely tuned balance between host immunity and chronic parasitism due to immunoregulation. Given that these reciprocal forces drive selection, experimental models of helminth infection are ideally suited for discovering how host protective immune responses adapt to the unique tissue niches inhabited by these large metazoan parasites. This review highlights the key discoveries in the immunology of helminth infection made over the last decade, from innate lymphoid cells to the emerging importance of neuroimmune connections. A particular emphasis is placed on the emerging areas within helminth immunology where the most growth is possible, including the advent of genetic manipulation of parasites to study immunology and the use of engineered T cells for therapeutic options. Lastly,we cover the status of human challenge trials with helminths as treatment for autoimmune disease, which taken together, stand to keep the study of parasitic worms at the forefront of immunology for years to come.

Lactobacillus acidophilus Induces a Strain-specific and Toll-Like Receptor 2-Dependent Enhancement of Intestinal Epithelial Tight Junction Barrier and Protection Against Intestinal Inflammation

Defective intestinal tight junction (TJ) barrier is an important pathogenic factor of inflammatory bowel disease. To date, no effective therapies that specifically target the intestinal TJ barrier are available. The purpose of this study was to identify probiotic bacterial species or strains that induce a rapid and sustained enhancement of intestinal TJ barrier and protect against the development of intestinal inflammation by targeting the TJ barrier. After high-throughput screening of >20 Lactobacillus and other probiotic bacterial species or strains, a specific strain of Lactobacillus acidophilus, referred to as LA1, uniquely produced a marked enhancement of the intestinal TJ barrier. LA1 attached to the apical membrane surface of intestinal epithelial cells in a Toll-like receptor (TLR)-2-dependent manner and caused a rapid increase in enterocyte TLR-2 membrane expression and TLR-2/TLR-1 and TLR-2/TLR-6 hetero-complex-dependent enhancement in intestinal TJ barrier function. Oral administration of LA1 caused a rapid enhancement in mouse intestinal TJ barrier, protected against a dextran sodium sulfate (DSS) increase in intestinal permeability, and prevented the DSS-induced colitis in a TLR-2- and intestinal TJ barrier-dependent manner. In conclusion, we report for the first time that a specific strain of LA causes a strain-specific enhancement of intestinal TJ barrier through a novel mechanism that involves the TLR-2 receptor complex and protects against the DSS-induced colitis by targeting the intestinal TJ barrier.

Ethanolic Garcinia mangostana extract and α-mangostin improve dextran sulfate sodium-induced ulcerative colitis via the suppression of inflammatory and oxidative responses in ICR mice

ETHNOPHARMACOLOGICAL RELEVANCE

Ulcerative colitis (UC) is an inflammatory disorder of the colon. Garcinia mangostana Linn. (GM) has been traditionally used for its anti-inflammatory and antioxidant activities.

AIM OF THE STUDY

The effects of GM and its bioactive constituent α-mangostin on dextran sulfate sodium (DSS)-induced UC in mice were investigated.

MATERIALS AND METHODS

Adult ICR mice (n = 63) were pretreated with ethanolic GM extract at 40, 200, and 1000 mg/kg/day (GM40, GM200, and GM1000), α-mangostin at 30 mg/kg/day, or sulfasalazine at 100 mg/kg/day (SA) for 7 consecutive days. On days 4-7, UC was induced in the mice by the oral administration of DSS (40 kDa, 6 g/kg/day), while control mice received distilled water. The UC disease activity index (DAI) and histological changes were recorded. The activities of myeloperoxidase, catalase, and superoxide dismutase, and the levels of reactive oxygen species (ROS), nitric oxide (NO), and malondialdehyde (MDA) were determined. The mRNA expression of inflammatory related genes including proinflammatory cytokine Tnf-α, Toll-like receptor (Tlr-2), adhesion molecules (Icam-1 and Vcam-1), and monocyte chemoattractant protein (Mcp-1) were evaluated.

RESULTS

Treatment with GM or α-mangostin decreased the UC DAI and protected against colon shortening and spleen and kidney enlargement. GM and α-mangostin prevented histological damage, reduced mast cell infiltration in the colon, and decreased myeloperoxidase activity. GM and α-mangostin increased catalase and superoxide dismutase activity and decreased ROS, NO, and MDA production. GM downregulated mRNA expression of Tnf-α, Tlr-2, Icam-1, Vcam-1, and Mcp-1.

CONCLUSIONS

GM and α-mangostin attenuated the severity of DSS-induced UC via anti-inflammatory and antioxidant effects. Therefore, GM is a promising candidate for development into a novel therapeutic agent for UC.

BPC 157 Rescued NSAID-cytotoxicity Via Stabilizing Intestinal Permeability and Enhancing Cytoprotection

The stable gastric pentadecapeptide BPC 157 protects stomach cells, maintains gastric integrity against various noxious agents such as alcohol, nonsteroidal anti-inflammatory drugs (NSAIDs), and exerts cytoprotection/ adaptive cytoprotection/organoprotection in other epithelia, that is, skin, liver, pancreas, heart, and brain. Especially BPC 157 counteracts gastric endothelial injury that precedes and induces damage to the gastric epithelium and generalizes "gastric endothelial protection" to protection of the endothelium of other vessels including thrombosis, prolonged bleeding, and thrombocytopenia. In this background, we put the importance of BPC 157 as a possible way of securing GI safety against NSAIDs-induced gastroenteropathy since still unmet medical needs to mitigate NSAIDs-induced cytotoxicity are urgent. Furthermore, gastrointestinal irritants such as physical or mental stress, NSAIDs administration, surfactants destroyer such as bile acids, alcohol can lead to leaky gut syndrome through increasing epithelial permeability. In this review article, we described the potential rescuing actions of BPC 157 against leaky gut syndrome after NSAIDs administration for the first time.

N-(3-oxododecanoyl)-l-homoserine lactone disrupts intestinal epithelial barrier through triggering apoptosis and collapsing extracellular matrix and tight junction

Microbes employ autoinducers of quorum sensing (QS) for population communication. Although the autoinducer of Pseudomonas aeruginosa LasI-LasR system, N-(3-oxododecanoyl)- l-homoserine lactone (3OC12), has been reported with deleterious effects on host cells, its biological effects on integrity of the intestinal epithelium and epithelial barrier are still unclear and need further investigation. In the present study, flow cytometry, transcriptome analysis and western blot technology have been adopted to investigate the potential molecular mechanisms of 3OC12 and its structurally similar analogs damage to intestinal epithelial cells. Our results indicated that 3OC12 and 3OC14 trigger apoptosis rather than necrosis and ferroptosis in intestinal epithelial cells. RNA-sequencing combined with bioinformatics analysis showed that 3OC12 and 3OC14 reduced the expression of genes from extracellular matrix (ECM)-receptor interaction pathway. Consistently, protein expressions from ECM and tight junction-associated pathway were significantly reduced after 3OC12 and 3OC14 challenge. In addition, 3OC12 and 3OC14 led to blocked cell cycle, decreased mitochondrial membrane potential, increased reactive oxygen species level and elevated Ca²⁺ concentration. Reversely, the antioxidant NAC could effectively mitigate the reduced expression of ECM and tight junction proteins caused by 3OC12 and 3OC14 challenge. Collectively, this study demonstrated that QS autoinducer exposure to intestinal epithelial cells ablates the ECM and tight junctions by triggering oxidative stress and apoptosis, and finally disrupts the intestinal epithelial barrier. These findings provide a rationale for defensing QS-dependent bacterial infections and potential role of NAC for alleviating the syndrome.

Organoid-based Models to Study the Role of Host-microbiota Interactions in IBD

The gut microbiota appears to play a central role in health, and alterations in the gut microbiota are observed in both forms of inflammatory bowel disease [IBD], namely Crohn's disease and ulcerative colitis. Yet, the mechanisms behind host-microbiota interactions in IBD, especially at the intestinal epithelial cell level, are not yet fully understood. Dissecting the role of host-microbiota interactions in disease onset and progression is pivotal, and requires representative models mimicking the gastrointestinal ecosystem, including the intestinal epithelium, the gut microbiota, and immune cells. New advancements in organoid microfluidics technology are facilitating the study of IBD-related microbial-epithelial cross-talk, and the discovery of novel microbial therapies. Here, we review different organoid-based ex vivo models that are currently available, and benchmark their suitability and limitations for specific research questions. Organoid applications, such as patient-derived organoid biobanks for microbial screening and 'omics technologies, are discussed, highlighting their potential to gain better mechanistic insights into disease mechanisms and eventually allow personalised medicine.

Clinical relevance of intestinal barrier dysfunction in common gastrointestinal diseases

The intestinal barrier is a complex and well-controlled physiological construct designed to separate luminal contents from the bowel wall. In this review, we focus on the intestinal barrier’s relationship with the host’s immune system interaction and the external environment, specifically the microbiome. The bowel allows the host to obtain nutrients vital to survival while protecting itself from harmful pathogens, luminal antigens, or other pro-inflammatory factors. Control over barrier function and the luminal milieu is maintained at the biochemical, cellular, and immunological level. However, disruption to this highly regulated environment can cause disease. Recent advances to the field have progressed the mechanistic understanding of compromised intestinal barrier function in the context of gastrointestinal pathology. There are numerous examples where bowel barrier dysfunction and the resulting interaction between the microbiome and the immune system has disease-triggering consequences. The purpose of this review is to summarize the clinical relevance of intestinal barrier dysfunction in common gastrointestinal and related diseases. This may help highlight the importance of restoring barrier function as a therapeutic mechanism of action in gastrointestinal pathology.

Translocation of Viable Gut Microbiota to Mesenteric Adipose Drives Formation of Creeping Fat in Humans

A mysterious feature of Crohn's disease (CD) is the extra-intestinal manifestation of "creeping fat" (CrF), defined as expansion of mesenteric adipose tissue around the inflamed and fibrotic intestine. In the current study, we explore whether microbial translocation in CD serves as a central cue for CrF development. We discovered a subset of mucosal-associated gut bacteria that consistently translocated and remained viable in CrF in CD ileal surgical resections, and identified Clostridium innocuum as a signature of this consortium with strain variation between mucosal and adipose isolates, suggesting preference for lipid-rich environments. Single-cell RNA sequencing characterized CrF as both pro-fibrotic and pro-adipogenic with a rich milieu of activated immune cells responding to microbial stimuli, which we confirm in gnotobiotic mice colonized with C. innocuum. Ex vivo validation of expression patterns suggests C. innocuum stimulates tissue remodeling via M2 macrophages, leading to an adipose tissue barrier that serves to prevent systemic dissemination of bacteria.

Altered paracellular permeability in intestinal cell monolayer challenged with lipopolysaccharide: Modulatory effects of pterostilbene metabolites

Epithelial barrier alteration is a central event in the pathogenesis of inflammatory bowel diseases. Lipopolysaccharide, correlated to the pathogenesis of such pathologies, has been demonstrated to cause altered membrane permeability, through the disruption and/or relocation of tight junction proteins, following redox-sensitive mitogen-activated protein kinases (MAPKs) modulation. Pterostilbene and its metabolite pinostilbene are natural stilbenoids which may reach relevant concentrations at intestinal level, together with their glucuronide and sulfate metabolites. The aim of our study was to evaluate the ability of these compounds to inhibit lipopolysaccharide-induced toxic effects on intestinal cell monolayer integrity and to explore the mechanism of action. Caco-2 cells, differentiated as enterocytes, were treated with lipopolysaccharide following pretreatment with the phenolic compounds at 1 μM physiological concentration. Caco-2 monolayer's permeability was monitored with time, measuring the transepithelial electrical resistance. Tight junction proteins were assessed by western blotting and immunofluorescence in lipopolysaccharide-treated cells, in relation to MAPK p38 and ERK1/2 activation. Pretreatment with all the phenolic compounds significantly slowed lipopolysaccharide-induced transepithelial electrical resistance decrease, preserved tight junction proteins levels and reduced MAPKs phosphorylation. The reported findings indicate that pterostilbene and its metabolites may counteract lipopolysaccharide-induced alteration of epithelial permeability, one of the initial events in the intestinal inflammatory process.

Dual role of Ca2+-activated Cl- channel transmembrane member 16A in lipopolysaccharide-induced intestinal epithelial barrier dysfunction in vitro

Dysfunction of intestinal epithelial Cl⁻ currents and channels have previously been reported in inflammatory intestinal diseases. However, the expression and function of the newly identified Ca²⁺-activated Cl⁻ channel transmembrane member 16A (TMEM16A) in the intestinal epithelium is unclear. In this study, we investigated the effects of TMEM16A on intestinal epithelial barrier function in vitro. Intestinal epithelial barrier dysfunction was modeled by lipopolysaccharide (LPS)-induced cell damage in intestinal epithelial IEC-6 cells and the effects of TMEM16A knockdown and overexpression on cell apoptosis and tight junctions were studied. Corresponding mRNA and protein expression levels were measured by quantitative real-time polymerase chain reaction, western blotting, and immunofluorescence analysis, respectively. TMEM16A expression was significantly increased by LPS, possibly via a process involving the transcription factor nuclear factor-κB and both Th1 and Th2 cytokines. Low- and high-dose LPS dysregulated tight junctions (high-myosin light-chain kinase expression) and cell apoptosis-dependent cell barrier dysfunction, respectively. TMEM16A aggravated cell barrier dysfunction in IEC-6 cells pretreated with low-dose LPS by activating ERK1/MLCK signaling pathways, but protected against cell barrier dysfunction by activating ERK/Bcl-2/Bax signaling pathways in IEC-6 cells pretreated with high-dose LPS. We concluded that TMEM16A played a dual role in LPS-induced epithelial dysfunction in vitro. The present results indicated the complex regulatory mechanisms and targeting of TMEM16A may provide potential treatment strategies for intestinal epithelial barrier damage, as well as forming the basis for future studies of the expression and function of TMEM16A in normal and inflammatory intestinal diseases in vivo.

Nanosphere-shaped ammonio methacrylate copolymers: converting a pharmaceutical inactive ingredient to efficient therapeutics for experimental colitis

Inflammatory bowel disease (IBD) refers to progressive inflammatory disorders that impair the gastrointestinal tract's structure and function. Given their selective accumulation in inflamed tissues, nanoparticles are promising drug delivery systems for IBD treatment. The hypothesis here was that drug-free nanoscaled cationic ammonio methacrylate copolymers (AMCNP) may have a beneficial therapeutic effect in murine TNBS-induced colitis. Type A and B AMCNP (RLNP and RSNP, respectively) were prepared and characterized in vitro, and were rectally administered in two concentrations (5 and 25 mg ml^-1) for the treatment of two grades of murine experimental colitis. The impact of the nanoparticles upon the inflammatory markers, circulating LPS, intestinal permeability and colonic leukocyte populations was examined. Both RLNP and RSNP led to a significant mitigation of mild to moderate experimental colitis, as evident from the substantial reduction of myeloperoxidase (MPO) and alkaline phosphatase (AP) activities (more than two-fold, P < 0.05) and various pro-inflammatory cytokine concentrations (TNF-α, IL-1β, IL-6, IL-12). The best therapeutic efficiency was observed when the particles were used at 5 mg ml^-1, while the more cationic RLNP performed superior. When used against a severe grade of colitis, RLNP (5 mg ml^-1) resulted in a significant decrease of tissue MPO and TNF-α. It was found that treatment with AMCNP resulted in significant intestinal immune cell depletion, intestinal barrier function improvement, and 1.5-2.5 times reduction of the systemic endotoxin concentration. These findings highlighted the fact that nanoscaling endows the cationic amphiphilic AMCs unique therapeutic properties, which help mitigate murine experimental colitis in the absence of any drug load. The results also provided a glimpse of possible underlying mechanisms through which nanoscaled AMCs might have exerted their therapeutic effect within this context.

Dextran Sodium Sulfate-Induced Impairment of Protein Trafficking and Alterations in Membrane Composition in Intestinal Caco-2 Cell Line

A key morphological feature of inflammatory bowel disease (IBD) is the loss of the barrier function of intestinal epithelial cells. The present study investigates endoplasmic reticulum (ER) stress in addition to alterations in protein and membrane trafficking in a dextran sulfate sodium (DSS)-induced IBD-like phenotype of intestinal Caco-2 cells in culture. DSS treatment significantly reduced the transepithelial electric resistance (TEER) and increased the epithelial permeability of Caco-2 cells, without affecting their viability. This was associated with an alteration in the expression levels of inflammatory factors in addition to an increase in the expression of the ER stress protein markers, namely immunoglobulin-binding protein (BiP), C/EBP homologous protein (CHOP), activation transcription factor 4 (ATF4), and X-box binding protein (XBP1). The DSS-induced ER-stress resulted in impaired intracellular trafficking and polarized sorting of sucrase-isomaltase (SI) and dipeptidyl peptidase-4 (DPPIV), which are normally sorted to the apical membrane via association with lipid rafts. The observed impaired sorting was caused by reduced cholesterol levels and subsequent distortion of the lipid rafts. The data presented confirm perturbation of ER homeostasis in DSS-treated Caco-2 cells, accompanied by impairment of membrane and protein trafficking resulting in altered membrane integrity, cellular polarity, and hence disrupted barrier function.

Deficiency in the anti-apoptotic protein DJ-1 promotes intestinal epithelial cell apoptosis and aggravates inflammatory bowel disease via p53

Parkinson disease autosomal recessive, early onset 7 (PARK7 or DJ-1) is involved in multiple physiological processes and exerts anti-apoptotic effects on multiple cell types. Increased intestinal epithelial cell (IEC) apoptosis and excessive activation of the p53 signaling pathway is a hallmark of inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease (CD). However, whether DJ-1 plays a role in colitis is unclear. To determine whether DJ-1 deficiency is involved in the p53 activation that results in IEC apoptosis in colitis, here we performed immunostaining, real-time PCR, and immunoblotting analyses to assess DJ-1 expression in human UC and CD samples. In the inflamed intestines of individuals with IBD, DJ-1 expression was decreased and negatively correlated with p53 expression. DJ-1 deficiency significantly aggravated colitis, evidenced by increased intestinal inflammation and exacerbated IEC apoptosis. Moreover, DJ-1 directly interacted with p53, and reduced DJ-1 levels increased p53 levels both in vivo and in vitro and were associated with decreased p53 degradation via the lysosomal pathway. We also induced experimental colitis with dextran sulfate sodium in mice and found that compared with DJ-1-/- mice, DJ-1-/-p53-/- mice have reduced apoptosis and inflammation and increased epithelial barrier integrity. Furthermore, pharmacological inhibition of p53 relieved inflammation in the DJ-1-/- mice. In conclusion, reduced DJ-1 expression promotes inflammation and IEC apoptosis via p53 in colitis, suggesting that the modulation of DJ-1 expression may be a potential therapeutic strategy for managing colitis.

c9, t11, c15-CLNA and t9, t11, c15-CLNA from Lactobacillus plantarum ZS2058 Ameliorate Dextran Sodium Sulfate-Induced Colitis in Mice

To investigate the specific functions of conjugated fatty acids (CFAs) produced by the probiotic bacterium, α-linolenic acid was isomerized by Lactobacillus plantarum ZS2058, and two different conjugated linolenic acid (CLNA) isomers were successfully isolated: c9, t11, c15-CLNA (CLNA1) and t9, t11, c15-CLNA (CLNA2). The effects and mechanism of CLNA crude extract and individual isomers on colitis were explored. CLNA significantly inhibited weight loss, the disease activity index, and colon shortening. Additionally, CLNA alleviated histological damage, protected colonic mucus layer integrity, and significantly upregulated the concentration of tight junction proteins (ZO-1, occludin, E-cadherin 1, and claudin-3). CLNA significantly attenuated the level of proinflammatory cytokines (TNF-α, IL-1β, and IL-6) while upregulating the expression of the colonic anti-inflammatory cytokine IL-10 and nuclear receptor peroxisome-activated receptor-γ. Moreover, CLNA increased the activity of oxidative stress-related enzymes (SOD, GSH, and CAT), and the myeloperoxidase activity was significantly decreased by CLNA. Meanwhile, the concentrations of CLNA in the liver and conjugated linoleic acid in the colonic content were significantly increased because of the treatment of CLNA. Furthermore, CLNA could rebalance the intestinal microbial composition of colitis mice, including increasing the α-diversity. CLNA1 and CLNA2 increased the abundance of Ruminococcus and Prevotella, respectively.

Gut microorganisms and their metabolites modulate the severity of acute colitis in a tryptophan metabolism-dependent manner

PURPOSE

Growing evidence shows that nutrient metabolism affects inflammatory bowel diseases (IBD) development. Previously, we showed that deficiency of indoleamine 2,3-dioxygenase 1 (Ido1), a tryptophan-catabolizing enzyme, reduced the severity of dextran sulfate sodium (DSS)-induced colitis in mice. However, the roles played by intestinal microbiota in generating the differences in disease progression between Ido1^+/+ and Ido1^-/- mice are unknown. Therefore, we aimed to investigate the interactions between the intestinal microbiome and host IDO1 in governing intestinal inflammatory responses.

METHODS

Microbial 16s rRNA sequencing was conducted in Ido1^+/+ and Ido1^-/- mice after DSS treatment. Bacteria-derived tryptophan metabolites were measured in urine. Transcriptome analysis revealed the effects of the metabolite and IDO1 expression in HCT116 cells. Colitis severity of Ido1^+/+ was compared to Ido1^-/- mice following fecal microbiota transplantation (FMT).

RESULTS

Microbiome analysis through 16S-rRNA gene sequencing showed that IDO1 deficiency increased intestinal bacteria that use tryptophan preferentially to produce indolic compounds. Urinary excretion of 3-indoxyl sulfate, a metabolized form of gut bacteria-derived indole, was significantly higher in Ido1^-/- than in Ido1^+/+ mice. Transcriptome analysis showed that tight junction transcripts were significantly increased by indole treatment in HCT116 cells; however, the effects were diminished by IDO1 overexpression. Using FMT experiments, we demonstrated that bacteria from Ido1^-/- mice could directly attenuate the severity of DSS-induced colitis.

CONCLUSIONS

Our results provide evidence that a genetic defect in utilizing tryptophan affects intestinal microbiota profiles, altering microbial metabolites, and colitis development. This suggests that the host and intestinal microbiota communicate through shared nutrient metabolic networks.

Occurrence, biological properties and potential effects on human health of β-casomorphin 7: Current knowledge and concerns

The genetic variant A1 of bovine β-casein (β-Cn) presents a His residue at a position 67 of the mature protein. This feature makes the Ile⁶⁶-His⁶⁷ bond more vulnerable to enzymatic cleavage, determining the release of the peptide β-Cn f(60-66), named β-casomorphin 7 (BCM7). BCM7 is an opioid-agonist for μ receptors, and it has been hypothesized to be involved in the development of different non-transmissible diseases in humans. In the last decade, studies have provided additional results on the potential health impact of β-Cn A1 and BCM7. These studies, here reviewed, highlighted a relation between the consumption of β-Cn A1 (and its derivative BCM7) and the increase of inflammatory response as well as discomfort at the gastrointestinal level. Conversely, the role of BCM7 and the effects of ingestion of β-Cn A1 on the onset or worsening of other non-transmissible diseases as caused or favored by still need proof of evidence. Overall, the reviewed literature demonstrates that the "β-Cn A1/BCM7 issue" remains an intriguing but not exhaustively explained topic in human nutrition. On this basis, policies in favor of breeding for β-Cn variants not releasing BCM7 and consumption of "A1-like" milk appear not yet sound for a healthier and safer nutrition.

Inflammatory bowel disease and targeted oral anti-TNFα therapy

Antibodies have provided invaluable treatment options for many diseases, with immunotherapy revolutionising the treatment of several inflammatory disorders including inflammatory bowel disease (IBD). Accumulating evidence suggests that IBD results from an inappropriate response to intestinal microbes and environmental factors in genetically susceptible individuals, with overactivity of the pro-inflammatory pathways. On a pathophysiological level, IBD is a complex disease with intestinal fibrosis, stenosis and an increased incidence of cancer observed in those whose disease is inadequately controlled over time. Regulating the actions of the pro-inflammatory cytokine human tumor necrosis factor-alpha (hTNFα) through the use of anti-TNFα monoclonal antibodies (e.g. infliximab, certolizumab, adalimumab and golimumab) has proven an effective intervention for IBD with their increased use a testament of their effectiveness. These agents are administered systemically thereby causing their distribution throughout the body in a condition that is localised to the gastrointestinal (GI) tract. Immunogenicity, the induction of anti-drug antibodies (ADAs), serum sickness and other undesirable side effects limit their use, whilst up to 50% of patients do not respond to initial therapy. Diseases confined to the GI tract are ideal for targeting by oral therapy which mitigates side effects and allows for lower doses to be administered. Several oral anti-TNFα agents have been investigated with success but are not yet in general clinical use. This partially reflects the fact that the oral administration of antibodies has many barriers including the harsh environment of the GI tract and the presence of enzymes including pepsin, trypsin and chymotrypsin in the intestine which provide significant challenges to targeted oral therapy.

The complex puzzle of dietary silver nanoparticles, mucus and microbiota in the gut

Hundreds of consumer and commercial products containing silver nanoparticles (AgNPs) are currently used in food, personal-care products, pharmaceutical, and many other applications. Human exposure to AgNPs includes oral intake, inhalation, and dermal contact. The aim of this review was to focus on oral intake, intentional and incidental of AgNPs where well-known antimicrobial characteristics that might affect the microbiome and mucus in the gastrointestinal tract (GIT). This critical review summarizes what is known regarding the impacts of AgNPs on gut homeostasis. It is fundamental to understand the forms of AgNPs and their physicochemical characterization before and during digestion. For example, lab-synthesized AgNPs differ from "real" ingestable AgNPs used as food additives and dietary supplements. Similarly, the gut environment alters the chemical and physical state of Ag that is ingested as AgNPs. Emerging research on in vitro and in vivo rodent and human indicated complex multi-directional relationships among AgNPs, the intestinal microbiota, and the epithelial mucus. It may be necessary to go beyond today's descriptive approach to a modeling-based ecosystem approach that might quantitatively integrate spatio-temporal interactions among microbial groups, host factors (e.g., mucus), and environmental factors, including lifestyle-based stressors. It is suggested that future research (1) utilize more representative AgNPs, focus on microbe/mucus interactions, (2) assess the effects of environmental stressors for longer and longitudinal conditions, and (3) be integrated using quantitative modeling.

Neonatal Injury Increases Gut Permeability by Epigenetically Suppressing E-Cadherin in Adulthood

Altered intestinal epithelial integrity is an important susceptibility trait in inflammatory bowel disease (IBD), and early life stressors are reported to contribute to this disease susceptibility in adulthood. To identify disease mechanisms associated with early-life trauma that exacerbate IBD in adulthood, we used a "double-hit" neonatal inflammation (NI) and adult inflammation (AI) model that exhibits more severe mucosal injury in the colon later in life. In this study, we explore the underlying mechanisms of this aggravated injury. In rats exposed to both NI and AI, we found sustained increases in colonic permeability accompanied by significantly attenuated expression of the epithelial junction protein E-cadherin. Quantitative RT-PCR revealed a decreased Cdh1 (gene of E-cadherin) mRNA expression in NI + AI rats compared with NI or AI rats. Next, we performed microRNA microarrays to identify potential regulators of E-cadherin in NI + AI rats. We confirmed the overexpression of miR-155, a predicted regulator of E-cadherin, and selected it for further analysis based on reported significance in human IBD. Using ingenuity pathway analysis software, the targets and related canonical pathway of miR-155 were analyzed. Mechanistic studies identified histone hyperacetylation at the Mir155 promoter in NI + AI rats, concomitant with elevated RNA polymerase II binding. In vitro, E-cadherin knockdown markedly increased epithelial cell permeability, as did overexpression of miR-155 mimics, which significantly suppressed E-cadherin protein. In vivo, NI + AI colonic permeability was significantly reversed with administration of miR-155 inhibitor rectally. Our collective findings indicate that early-life inflammatory stressors trigger a significant and sustained epithelial injury by suppressing E-cadherin through epigenetic mechanisms.

Biotin Supplementation Ameliorates Murine Colitis by Preventing NF-κB Activation

BACKGROUND & AIMS

Biotin is a water-soluble vitamin that is indispensable for human health. Biotin deficiency can cause failure-to-thrive, immunodeficiency, alopecia, dermatitis, and conjunctivitis. We previously reported that biotin deficiency also can lead to severe colitis in mice, which is completely reversed with supplementation. Our aim in this study was to determine if high-dose biotin supplementation can provide a therapeutic benefit in a preclinical model for inflammatory bowel disease (IBD) and to identify the molecular mechanism by which this occurs.

METHODS

Mice were challenged with dextran sodium sulfate to induce colitis and were treated with 1 mmol/L biotin to induce or maintain remission. Clinical response was monitored by the Disease Activity Index and fecal calprotectin levels. The colon tissue was investigated for histology, length, as well as expression of inflammatory cytokines (interleukin 6, tumor necrosis factor-α, interleukin 1β), intestinal permeability, tight junctions (zonula occludens-1 and claudin-2), and the transcription factor nuclear factor-κB (NF-κB).

RESULTS

Biotin therapy led to delayed onset and severity of colitis as well as accelerated healing. There was improvement in the Disease Activity Index, fecal calprotectin levels, colon length, and histology. In addition, biotin-treated mice had reduced expression of inflammatory cytokines, reduced intestinal permeability, and reduced activation of NF-κB.

CONCLUSIONS

Oral supplementation with biotin provides benefit for maintenance and induction of remission in the dextran sodium sulfate preclinical model for IBD. Biotin does this by reducing the activation of NF-κB, which prevents the production of inflammatory cytokines and helps maintain the integrity of the intestinal barrier. Clinically, the NF-κB pathway is important in the development of IBD and this finding suggests that biotin may have therapeutic potential for patients with IBD.

Comparative pharmacokinetics of verapamil and norverapamil in normal and ulcerative colitis rats after oral administration of low and high dose verapamil by UPLC-MS/MS

In this study, UC rat model was established by administration of 5% (w/v) dextran sulfate sodium, and the pharmacokinetics of verapamil and norverapamil were evaluated in normal and UC rats using UPLC-MS/MS after oral administration of 5 mg/kg and 50 mg/kg verapamil.The peak concentration (C_max) and the area under plasma concentration-time curves (AUC) of verapamil in UC rats after oral administration of 5 mg/kg were significantly greater (2.5 times and 2 times, respectively) than those in normal rats, but the clearance rate (Cl) was significantly lower (by 50%). For norverapamil, C_max and AUC were significantly greater (2.8 times and 2.5 times, respectively), and Cl was significantly lower (by 45%). But, pharmacokinetic parameters of verapamil and norverapamil after oral administration of 50 mg/kg were no significant differences between UC and normal rats.The better absorption and poor excretion for low-dose verapamil may be attributed to down-regulation of P-gp expression in the intestine and kidney. No significant differences of pharmacokinetic parameters for high-dose verapamil may be explained as the saturation of an efflux mechanism.The findings of this study suggested that in UC patients, doses of verapamil should be decreased when low-dose verapamil was orally administrated.

Nanoparticles for the regulation of intestinal inflammation: opportunities and challenges

Prevalence of chronic inflammation of the gastrointestinal tract is increasing, emerging as a public health challenge. Conventional drug delivery systems targeting the colon have improved the treatment of inflammatory bowel disease. However, therapy frequently results in inconsistent efficacy and toxicity problems. Novel approaches based on nanoparticles offer several advantages over conventional dosage forms due to their ability to selectively target inflamed tissues. Several formulation efforts have been made in order to obtain increasingly selective nanosized systems, some with promising results in animal models of colitis. Despite all advances, no nanomedicines are yet approved for clinical use in inflammatory bowel disease. This review discusses the most recent efforts made toward the development of nanoparticles for regulating chronic intestinal inflammation.

Claudin-2 suppresses GEF-H1, RHOA, and MRTF, thereby impacting proliferation and profibrotic phenotype of tubular cells

The tight junctional pore-forming protein claudin-2 (CLDN-2) mediates paracellular Na⁺ and water transport in leaky epithelia and alters cancer cell proliferation. Previously, we reported that tumor necrosis factor-α time-dependently alters CLDN-2 expression in tubular epithelial cells. Here, we found a similar expression pattern in a mouse kidney injury model (unilateral ureteral obstruction), consisting of an initial increase followed by a drop in CLDN-2 protein expression. CLDN-2 silencing in LLC-PK¹ tubular cells induced activation and phosphorylation of guanine nucleotide exchange factor H1 (GEF-H1), leading to Ras homolog family member A (RHOA) activation. Silencing of other claudins had no such effects, and re-expression of an siRNA-resistant CLDN-2 prevented RHOA activation, indicating specific effects of CLDN-2 on RHOA. Moreover, kidneys from CLDN-2 knockout mice had elevated levels of active RHOA. Of note, CLDN-2 silencing reduced LLC-PK1 cell proliferation and elevated expression of cyclin-dependent kinase inhibitor P27 (P27KIP1) in a GEF-H1/RHOA-dependent manner. P27KIP1 silencing abrogated the effects of CLDN-2 depletion on proliferation. CLDN-2 loss also activated myocardin-related transcription factor (MRTF), a fibrogenic RHOA effector, and elevated expression of connective tissue growth factor and smooth muscle actin. Finally, CLDN-2 down-regulation contributed to RHOA activation and smooth muscle actin expression induced by prolonged tumor necrosis factor-α treatment, because they were mitigated by re-expression of CLDN-2. Our results indicate that CLDN-2 suppresses GEF-H1/RHOA. CLDN-2 down-regulation, for example, by inflammation, can reduce proliferation and promote MRTF activation through RHOA. These findings suggest that the initial CLDN-2 elevation might aid epithelial regeneration, and CLDN-2 loss could contribute to fibrotic reprogramming.

Jasonia glutinosa (L.) DC., a traditional herbal medicine, reduces inflammation, oxidative stress and protects the intestinal barrier in a murine model of colitis

Jasonia glutinosa (L.) DC., known as rock tea (RT), is traditionally used in Spain as a digestive due to its beneficial properties in bowel disorders. The pharmacological nature of these properties has not been established yet. The aim of this work was to evaluate the therapeutic utility of RT in experimental colitis and to identify chemical constituents with anti-inflammatory and/or anti-oxidative properties. RT extract was prepared with ethanol in a Soxhlet apparatus and analysed by HPLC-DAD. Superoxide radical scavenging properties, xanthine oxidase and lipoxygenase (5-LOX) inhibitory activity, and capability to lower nitric oxide (NO) and tumor necrosis factor α (TNF-α) levels were measured in cell-free and cell-based assays. In the 2.5%-dextran-sodium sulphate (DSS) injury-repair model of ulcerative colitis (UC), mice were daily treated with sulfasalazine (SSZ, as reference drug, 100 mg/kg bw), RT (5, 25 and 50 mg/kg bw, p.o.), or vehicle over 20 days. Colitis was scored daily. Colon samples were examined macroscopically and histopathologically. Protein levels of myeloperoxidase (MPO), interleukins 6, and 10 (IL-6, IL-10), inducible NO synthase (iNOS), and cyclooxygenase-2 (COX-2) were studied as markers of oxidative stress and inflammatory activity. The integrity of the apical epithelial layer was assessed by immunofluorescence staining of zonula ocludens-1 (ZO-1). Finally, intestinal contractility was also evaluated by isometric myography. Fifteen phenolic compounds and three pigments were identified and quantified, of which caffeoylquinic acids, and the flavonoid, quercetin-3-O-galactoside, were the most abundant. RT extract significantly scavenged superoxide radicals, inhibited 5-LOX activity, and lowered NO and TNF-α levels. DSS-treated mice receiving RT scored clinically lower than controls during the first 3 days of DSS treatment and during the recovery period. SSZ was less effective than RT. Anatomical and histological examination of colon samples revealed that RT significantly prevented colon shortening, increased colon thickness, and lowered the macroscopic damage score. RT also significantly prevented the increase of MPO activity, IL-6 levels, iNOS and COX-2 expression, the loss of ZO-1 apical expression, and normalized contractility disturbances. In conclusion, daily administration of RT showed therapeutic properties in the DSS-model of UC. The benefits of RT can likely be attributed to its anti-inflammatory and antioxidant phenolic and flavonoid constituents.

A ropy exopolysaccharide producing strain Bifidobacterium longum subsp. longum YS108R alleviates DSS-induced colitis by maintenance of the mucosal barrier and gut microbiota modulation

B. longum has been reported to exert an alleviative effect on colitis, but the results also suggested significant differences among strains. Here in this study, we compared the effect of B. longum subsp. longum strains with different properties in EPS production on DSS-induced colitis. To investigate the alleviative effect of a ropy-exopolysaccharide (EPS) producing strain, Bifidobacterium longum subsp. longum YS108R, on experimental colitis, C57BL/6J mice (male, 6-8 weeks old) were randomly assigned to six groups (n = 8): normal control, DSS colitis and four DSS colitis groups orally administered with three B. longum subsp. longum strains (YS108R, C11A10B and HAN4-25) and B. animalis subsp. lactis BB12, respectively, in which YS108R produced ropy-EPS, C11A10B produced non-ropy-EPS, HAN4-25 did not produce EPS and BB12 was set as a positive control. Ropy-EPS producing strain YS108R could alleviate the symptoms and remit inflammation induced by DSS, in which YS108R could decrease the pro-inflammatory cytokine IL-6 and IL-17A levels after DSS challenge (from 102 ± 45.22 to 37.95 ± 20.33 pg mL-1 and from 22.14 ± 5.43 to 12.58 ± 2.74, p < 0.05), but another non-ropy-EPS producing strain C11A10B did not decrease the levels of these pro-inflammatory cytokines. Furthermore, YS108R could maintain the expression levels of genes related to the mucosal barrier, but strain HAN4-25, a non-EPS producer, was not able to maintain the expression levels of these genes after DSS challenge. Analysis of gut microbiota showed that DSS treatment significantly increased the relative abundance of Enterobacteriaceae and Peptostreptococcaceae (0.2623 ± 0.162 and 0.0512 ± 0.0361) and decreased the relative abundance of S24-7 (0.042 ± 0.0326); however, YS108R administration could decrease the relative abundance of Enterobacteriaceae and Peptostreptococcaceae to 0.0848 ± 0.0399 and 0.0032 ± 0.0047 and increase the relative abundance of S24-7 to 0.2625 ± 0.0566 (p < 0.05). The results showed that B. longum subsp. longum YS108R could alleviate DSS-induced colitis by modulating the inflammation related cytokines, maintenance of the normal mucosal barrier and reverting the change of microbiota.

Type 2 Innate Lymphoid Cells in Liver and Gut: From Current Knowledge to Future Perspectives

Innate lymphoid cells (ILCs) represent a heterogeneous population of recently discovered immune cells that mirror the functions of adaptive T lymphocytes. However, ILCs are devoid of specific antigen receptors and cellular activation depends on environmental cytokines, rendering them as early regulators of immune responses. Type 2 innate lymphoid cells (ILC2s) respond to alarmins, such as interleukin-25 and -33 and shape Th2-associated immunity by expressing IL-5 and IL-13 in a GATA3-dependent manner. In addition, ILC2s express the epidermal growth factor-like molecule Amphiregulin thereby promoting regeneration of injured tissue during inflammation. The gut and liver confer nutrient metabolism and bidirectional exchange of products, known as the gut-liver axis. Accordingly, both organs are continuously exposed to a large variety of harmless antigens. This requires avoidance of immunity, which is established by a tolerogenic environment in the gut and liver. However, dysregulations within the one organ are assumed to influence vitality of the other and frequently promote chronic inflammatory settings with poor prognosis. Intensive research within the last years has revealed that ILC2s are involved in acute and chronic inflammatory settings of gut and liver. Here, we highlight the roles of ILC2s in intestinal and hepatic inflammation and discuss a regulatory potential.

The Influence of Maternal-Foetal Parameters on Concentrations of Zonulin and Calprotectin in the Blood and Stool of Healthy Newborns during the First Seven Days of Life. An Observational Prospective Cohort Study

Background: It can be hypothetically assumed that maternal and perinatal factors influence the intestinal barrier. Methods: The study was conducted with 100 healthy, full-term newborns breastfed in the first week of life, with similar analyses for their mothers. Zonulin and calprotectin levels were used as intestinal permeability markers. Results: The median (range) zonulin concentrations (ng/mL) were in mothers: serum, 21.39 (6.39–57.54); stool, 82.23 (42.52–225.74); and newborns: serum cord blood, 11.14 (5.82–52.34); meconium, 54.15 (1.36–700.65); and stool at age seven days, 114.41 (29.38–593.72). Calprotectin median (range) concentrations (µg/mL) in mothers were: stool, 74.79 (3.89–211.77); and newborns: meconium, 154.76 (6.93–8884.11); and stool at age seven days 139.12 (11.89–627.35). The use of antibiotics during pregnancy resulted in higher zonulin concentrations in umbilical-cord serum and calprotectin concentrations in newborn stool at seven days, while antibiotic therapy during labour resulted in higher zonulin concentrations in the stool of newborns at seven days. Zonulin concentrations in the stool of newborns (at seven days) who were born via caesarean section were higher compared to with vaginal birth. With further analyses, caesarean section was found to have a greater effect on zonulin concentrations than prophylactic administration of antibiotics in the perinatal period. Pregnancy mass gain >18 kg was associated with higher calprotectin concentrations in maternal stool. Body Mass Index (BMI) increase >5.7 during pregnancy was associated with decreased zonulin concentrations in maternal stool and increased calprotectin concentrations in stool of mothers and newborns at seven days. There was also a negative correlation between higher BMI increase in pregnancy and maternal zonulin stool concentrations and a positive correlation between BMI increase in pregnancy and maternal calprotectin stool concentrations. Conclusion: Maternal-foetal factors such as caesarean section, antibiotic therapy during pregnancy, as well as change in mother’s BMI during pregnancy may increase intestinal permeability in newborns. Changes in body mass during pregnancy can also affect intestinal permeability in mothers. However, health consequences associated with increased intestinal permeability during the first days of life are unknown. Additionally, before the zonulin and calprotectin tests can be adopted as universal diagnostic applications to assess increased intestinal permeability, validation of these tests is necessary.

STAT4 activation by leukemia inhibitory factor confers a therapeutic effect on intestinal inflammation

T helper 17 (Th17)-cell differentiation triggered by interleukin-6 (IL-6) via STAT3 activation promotes inflammation in inflammatory bowel disease (IBD) patients. However, leukemia inhibitory factor (LIF), an IL-6 family cytokine, restricts inflammation by blocking Th17-cell differentiation via an unknown mechanism. Here, we report that microbiota dysregulation promotes LIF secretion by intestinal epithelial cells (IECs) in a mouse colitis model. LIF greatly activates STAT4 phosphorylation on multiple SPXX elements within the C-terminal transcription regulation domain. STAT4 and STAT3 act reciprocally on both canonical cis-inducible elements (SIEs) and noncanonical "AGG" elements at different loci. In lamina propria lymphocytes (LPLs), STAT4 activation by LIF blocks STAT3-dependent Il17a/Il17f promoter activation, whereas in IECs, LIF bypasses the extraordinarily low level of STAT4 to induce YAP gene expression via STAT3 activation. In addition, we found that the administration of LIF is sufficient to restore microbiome homeostasis. Thus, LIF effectively inhibits Th17 accumulation and promotes repair of damaged intestinal epithelium in inflamed colon, serves as a potential therapy for IBD.

The Immunomodulatory Properties of Propyl-Propane Thiosulfonate Contribute to its Intestinal Anti-Inflammatory Effect in Experimental Colitis

SCOPE

Propyl-propane thiosulfonate (PTSO) is a component isolated from garlic (Allium sativum) with antioxidant, anti-inflammatory, immunomodulatory, and antimicrobial properties. In consequence, PTSO can be a potential candidate for the treatment of inflammatory bowel diseases.

METHODS AND RESULTS

The anti-inflammatory effects of PTSO are studied in two mice models of colitis: 2,4-dinitrobenzene sulfonic acid (DNBS) (PTSO doses: 0.01-10 mg kg^-1 ) and dextran sodium sulfate (DSS) (PTSO doses: 0.01-0.1 mg kg^-1 ). The immunomodulatory effects of PTSO (0.1-25 µm) are also shown in vitro in Caco-2 and THP-1 cells, reducing the production of pro-inflammatory mediators and downregulating mitogen-activated protein kinases (MAPKs) signaling pathways. This compound displays beneficial effects in both models of mouse colitis by reducing the expression of different pro-inflammatory mediators and improving the intestinal epithelial barrier integrity. Moreover, PTSO ameliorates the altered gut microbiota composition observed in DSS colitic mice.

CONCLUSION

PTSO exerts intestinal anti-inflammatory activity in experimental colitis in mice. This anti-inflammatory activity can be associated with the immunomodulatory properties of PTSO through the regulation of the activity of cells involved in the inflammatory response. Furthermore, PTSO is able to restore the intestinal epithelial barrier function and to ameliorate the intestinal microbiota homeostasis, thus supporting its future development in human IBD.

Physiology and molecular biology of barrier mechanisms in the fetal and neonatal brain

Properties of the local internal environment of the adult brain are tightly controlled providing a stable milieu essential for its normal function. The mechanisms involved in this complex control are structural, molecular and physiological (influx and efflux transporters) frequently referred to as the 'blood-brain barrier'. These mechanisms include regulation of ion levels in brain interstitial fluid essential for normal neuronal function, supply of nutrients, removal of metabolic products, and prevention of entry or elimination of toxic agents. A key feature is cerebrospinal fluid secretion and turnover. This is much less during development, allowing greater accumulation of permeating molecules. The overall effect of these mechanisms is to tightly control the exchange of molecules into and out of the brain. This review presents experimental evidence currently available on the status of these mechanisms in developing brain. It has been frequently stated for over nearly a century that the blood-brain barrier is not present or at least is functionally deficient in the embryo, fetus and newborn. We suggest the alternative hypothesis that the barrier mechanisms in developing brain are likely to be appropriately matched to each stage of its development. The contributions of different barrier mechanisms, such as changes in constituents of cerebrospinal fluid in relation to specific features of brain development, for example neurogenesis, are only beginning to be studied. The evidence on this previously neglected aspect of brain barrier function is outlined. We also suggest future directions this field could follow with special emphasis on potential applications in a clinical setting.

Dietary restriction improves intestinal cellular fitness to enhance gut barrier function and lifespan in D. melanogaster

Loss of gut integrity is linked to various human diseases including inflammatory bowel disease. However, the mechanisms that lead to loss of barrier function remain poorly understood. Using D. melanogaster, we demonstrate that dietary restriction (DR) slows the age-related decline in intestinal integrity by enhancing enterocyte cellular fitness through up-regulation of dMyc in the intestinal epithelium. Reduction of dMyc in enterocytes induced cell death, which leads to increased gut permeability and reduced lifespan upon DR. Genetic mosaic and epistasis analyses suggest that cell competition, whereby neighboring cells eliminate unfit cells by apoptosis, mediates cell death in enterocytes with reduced levels of dMyc. We observed that enterocyte apoptosis was necessary for the increased gut permeability and shortened lifespan upon loss of dMyc. Furthermore, moderate activation of dMyc in the post-mitotic enteroblasts and enterocytes was sufficient to extend health-span on rich nutrient diets. We propose that dMyc acts as a barometer of enterocyte cell fitness impacting intestinal barrier function in response to changes in diet and age.

Genome-wide DNA Methylation in Treatment-naïve Ulcerative Colitis

BACKGROUND AND AIMS

The aim of this study was to investigate the genome-wide DNA methylation status in treatment-naïve ulcerative colitis [UC], and to explore the relationship between DNA methylation patterns and gene expression levels in tissue biopsies from a well-stratified treatment-naïve UC patient group.

METHODS

Mucosal biopsies from treatment-naïve patients [n = 10], and a healthy control group [n = 11] underwent genome-wide DNA bisulfite sequencing. Principal component analysis [PCA] and diverse statistical methods were applied to obtain a dataset of differentially methylated genes. DNA methylation annotation was investigated using the UCSC Genome Browser. Gene set enrichments were obtained using the Kyoto Encyclopaedia of Genes and Genomes [KEGG] and PANTHER.

RESULTS

Of all significantly differentially expressed genes [DEGs], 25% correlated with DNA methylation patterns; 30% of these genes were methylated at CpG sites near their transcription start site [TSS]. Hyper-methylation was observed for genes involved in homeostasis and defence, whereas hypo-methylation was observed for genes playing a role in immune response [i.e. chemokines and interleukins]. Of the differentially DNA methylated genes, 25 were identified as inflammatory bowel disease [IBD] susceptibility genes. Four genes [DEFFA6, REG1B, BTNL3, OLFM4] showed DNA methylation in the absence of known CpG islands.

CONCLUSIONS

Genome-wide DNA methylation analysis revealed distinctive functional patterns for hyper-and hypo-methylation in treatment-naïve UC. These distinct patterns could be of importance in the development and pathogenesis of UC. Further investigation of DNA methylation patterns may be useful in the development of the targeting of epigenetic processes, and may allow new treatment and target strategies for UC patients.

Qingchang Suppository Ameliorates Colonic Vascular Permeability in Dextran-Sulfate-Sodium-Induced Colitis

Ulcerative colitis (UC), with a long course and repeated attack, severely affects patient's life quality and increases economic burden all over the world. However, the concrete causes and mechanisms of UC are still unclear, but it is generally considered that many factors participate in this process. Qingchang Suppository (QCS) has been used in treating rectitis and colitis for about 30 years in Shanghai, China. Its satisfactory clinical effects have been proved. The aim of this study is to investigate the effect and mechanisms of QCS on colonic vascular endothelial barrier in dextran sulfate sodium (DSS)-induced colitis. The results indicated that increased vascular permeability (VP) appeared earlier than increased intestinal epithelial permeability (EP) in the process of DSS-induced colitis. QCS attenuated colonic tissue edema, vascular congestion and inflammatory cell infiltration. QCS inhibited the elevation of MPO, TNF-α, and IL-6 levels in colon tissues and alleviated the microvascular damage induced by DSS. QCS also improved colonic hypoxia and decreased the expression of VEGF, HIF-1α, and iNOS. These results revealed that QCS can reduce colonic VP and can improve vascular endothelial barrier function maybe by regulating the VEGF/HIF-1α signaling pathway.

Intestinal anti-inflammatory effect of the probiotic Saccharomyces boulardii in DSS-induced colitis in mice: Impact on microRNAs expression and gut microbiota composition

The beneficial effects exerted by probiotics in inflammatory bowel disease (IBD) are well known, although their exact mechanisms have not been fully elucidated, and only few studies have focused on their impact on selected miRNAs and the gut microbiota composition. Therefore, our aim was to correlate the intestinal anti-inflammatory activity of the probiotic Saccharomyces boulardii in the dextran sodium sulphate (DSS) model of mouse colitis and the changes induced in miRNA expression and gut microbiota populations. Probiotic was given orally (5×10⁹ CFU) to C57BL/6 mice for 26 days. After 2 weeks, the colitis was induced adding DSS to the drinking water. Mice were scored daily using a Disease Activity Index (DAI). After sacrifice, the colonic specimens were evaluated by determining the expression of inflammatory markers and micro-RNAs by qRT-PCR. Moreover, changes in microbiota populations were evaluated by pyrosequencing. Probiotic ameliorated the colonic damage induced by DSS, as evidenced by lower DAI values and colonic weight/length compared with untreated mice. The treatment modified the colonic expression of different inflammatory markers and the epithelial integrity proteins, and induced changes in micro-RNAs expression. Moreover, microbiota characterization showed that probiotic treatment increased bacterial diversity, thus ameliorating the dysbiosis produced by DSS-colitis. Saccharomyces boulardii exerted intestinal anti-inflammatory effects in DSS-mouse colitis, through the modulation in the immune response, involving modification of altered miRNA expression, being associated to the improvement of the inflammation-associated dysbiosis in the intestinal lumen, which could be of great interest to control the complex pathogenesis of IBD.

Functions of EpCAM in physiological processes and diseases (Review)

EpCAM (epithelial cell adhesion molecule) is a type I transmembrane glycoprotein, which was originally identified as a tumor-associated antigen due to its high expression level in rapidly growing epithelial tumors. Germ line mutations of the human EpCAM gene have been indicated as the cause of congenital tufting enteropathy. Previous studies based on cell models have revealed that EpCAM contributes to various biological processes including cell adhesion, signaling, migration and proliferation. Due to the previous lack of genetic animal models, the in vivo functions of EpCAM remain largely unknown. However, EpCAM genetic animal models have recently been generated, and are useful for understanding the functions of EpCAM. The authors here briefly review the functions and mechanisms of EpCAM in physiological processes and different diseases.

Protective Effects of a Lipid Extract from Hard-Shelled Mussel (Mytilus coruscus) on Intestinal Integrity after Lipopolysaccharide Challenge in Mice

This study investigated the protective effects of a lipid extract from hard-shelled mussel (HMLE) on intestinal integrity and the underlying mechanisms after a lipopolysaccharide (LPS) challenge in mice by using a 3 × 2 factorial design. Mice received olive oil, fish oil, and HMLE (n = 12 per group) by using gastric gavage for six weeks, respectively. Then half the mice in each group was injected intraperitoneally with LPS and the other half with phosphate buffered saline. Four hours after injection, mice were sacrificed and samples were collected. n-3 PUFAs were significantly enriched in erythrocytes following fish oil and HMLE supplementation. Both fish oil and HMLE improved intestinal morphology by restoring the ileac villus height and barrier function, which is indicated by decreased colonic myeloperoxidase activity and increased diamine oxidase activity as well as enhanced mRNA expression of intestinal tight junction proteins known as occludin and claudin-1 when compared with olive oil. In addition, both fish oil and HMLE increased colon production and the expression of anti-inflammatory cytokine, IL-10, while they inhibited the abnormal production and expression of pro-inflammatory cytokines including TNF-α, IL-1β, and IL-6 relative to the olive oil. Lastly, in comparison with olive oil, both fish oil and HMLE downregulated the TLR-4 signaling pathway by reducing the expression of two key molecules in this pathway, which are called TLR-4 and MyD88. These results suggest that HMLE had a protective effect on intestinal integrity after the LPS challenge, which was equivalent to that of fish oil. This effect might be associated with the regulation of inflammatory mediators and the inhibition of the TLR-4 signaling pathway.

Mucus: An Underestimated Gut Target for Environmental Pollutants and Food Additives

Synthetic chemicals (environmental pollutants, food additives) are widely used for many industrial purposes and consumer-related applications, which implies, through manufactured products, diet, and environment, a repeated exposure of the general population with growing concern regarding health disorders. The gastrointestinal tract is the first physical and biological barrier against these compounds, and thus their first target. Mounting evidence indicates that the gut microbiota represents a major player in the toxicity of environmental pollutants and food additives; however, little is known on the toxicological relevance of the mucus/pollutant interplay, even though mucus is increasingly recognized as essential in gut homeostasis. Here, we aimed at describing how environmental pollutants (heavy metals, pesticides, and other persistent organic pollutants) and food additives (emulsifiers, nanomaterials) might interact with mucus and mucus-related microbial species; that is, “mucophilic” bacteria such as mucus degraders. This review highlights that intestinal mucus, either directly or through its crosstalk with the gut microbiota, is a key, yet underestimated gut player that must be considered for better risk assessment and management of environmental pollution.

The Administration of Escherichia coli Nissle 1917 Ameliorates Development of DSS-Induced Colitis in Mice

The beneficial effects of probiotics on immune-based pathologies such as inflammatory bowel disease (IBD) have been well reported. However, their exact mechanisms have not been fully elucidated. Few studies have focused on the impact of probiotics on the composition of the colonic microbiota. The aim of the present study was to correlate the intestinal anti-inflammatory activity of the probiotic Escherichia coli Nissle 1917 (EcN) in the dextran sodium sulfate (DSS) model of mouse colitis with the changes induced in colonic microbiota populations. EcN prevented the DSS-induced colonic damage, as evidenced by lower disease activity index (DAI) values and colonic weight/length ratio, when compared with untreated control mice. The beneficial effects were confirmed biochemically, since the probiotic treatment improved the colonic expression of different cytokines and proteins involved in epithelial integrity. In addition, it restored the expression of different micro-RNAs (miR-143, miR-150, miR-155, miR-223, and miR-375) involved in the inflammatory response that occurs in colitic mice. Finally, the characterization of the colonic microbiota by pyrosequencing showed that the probiotic administration was able to counteract the dysbiosis associated with the intestinal inflammatory process. This effect was evidenced by an increase in bacterial diversity in comparison with untreated colitic mice. The intestinal anti-inflammatory effects of the probiotic EcN were associated with an amelioration of the altered gut microbiome in mouse experimental colitis, especially when considering bacterial diversity, which is reduced in these intestinal conditions. Moreover, this probiotic has shown an ability to modulate expression levels of miRNAs and different mediators of the immune response involved in gut inflammation. This modulation could also be of great interest to understand the mechanism of action of this probiotic in the treatment of IBD.

A Synbiotic with Tumor Necrosis Factor-α Inhibitory Activity Ameliorates Experimental Jejunoileal Mucosal Injury

Despite the recent development of biological modifiers for inflammatory bowel diseases (IBD), there continues to be considerable interest in fermented medicines because of its negligible adverse effects. We previously showed that the synbiotic Gut Working Tablet (GWT) alleviates experimental colitis. Here we show that GWT is capable of ameliorating jejunoileal mucosal injury, which is frequently seen with IBD. We created experimental jejunoileal mucositis in rats by injection of methotrexate (MTX) which increases intestinal permeability, a hallmark finding of IBD. Administering GWT to MTX-injected rats restored intestinal integrity by reversing villi shortening, crypt loss, and goblet cell depletion in the mucosa. Also GWT reduced activities of myeloperoxidase and lipid peroxidase and increased superoxide dismutase activity, which is critical for maintaining intestinal function. We further found that GWT suppressed mRNA expression of tumor necrosis factor-α (TNF-α) and interleukin-12 (IL-12) in macrophage and reduced TNF-α mRNA expression in specimens with experimental colitis, which is in contrast to VSL#3 that enhanced TNF-α production. Together, the current and previous animal studies clearly demonstrate the protective role of GWT in chemically induced enterocolitis. Crohn's disease, a well-known IBD, can affect any portion of the intestine, and these results suggest that GWT may be useful as a novel therapeutic or maintenance therapy for IBD.

Pathophysiology of IBD associated diarrhea

Inflammatory bowel diseases broadly categorized into Crohn's disease (CD) and ulcerative colitis (UC), are chronic inflammatory disorders of the gastrointestinal tract with increasing prevalence worldwide. The etiology of the disease is complex and involves a combination of genetic, environmental, immunological and gut microbial factors. Recurring and bloody diarrhea is the most prevalent and debilitating symptom in IBD. The pathogenesis of IBD-associated diarrhea is multifactorial and is essentially an outcome of mucosal damage caused by persistent inflammation resulting in dysregulated intestinal ion transport, impaired epithelial barrier function and increased accessibility of the pathogens to the intestinal mucosa. Altered expression and/or function of epithelial ion transporters and channels is the principle cause of electrolyte retention and water accumulation in the intestinal lumen leading to diarrhea in IBD. Aberrant barrier function further contributes to diarrhea via leak-flux mechanism. Mucosal penetration of enteric pathogens promotes dysbiosis and exacerbates the underlying immune system further perpetuating IBD associated-tissue damage and diarrhea. Here, we review the mechanisms of impaired ion transport and loss of epithelial barrier function contributing to diarrhea associated with IBD.

The bile acids, deoxycholic acid and ursodeoxycholic acid, regulate colonic epithelial wound healing

The intestinal epithelium constitutes an innate barrier which, upon injury, undergoes self-repair processes known as restitution. Although bile acids are known as important regulators of epithelial function in health and disease, their effects on wound healing processes are not yet clear. Here we set out to investigate the effects of the colonic bile acids, deoxycholic acid (DCA) and ursodeoxycholic acid (UDCA), on epithelial restitution. Wound healing in T₈₄ cell monolayers grown on transparent, permeable supports was assessed over 48 h with or without bile acids. Cell migration was measured in Boyden chambers. mRNA and protein expression were measured by RT-PCR and Western blotting. DCA (50-150 µM) significantly inhibited wound closure in cultured epithelial monolayers and attenuated cell migration in Boyden chamber assays. DCA also induced nuclear accumulation of the farnesoid X receptor (FXR), whereas an FXR agonist, GW4064 (10 µM), inhibited wound closure. Both DCA and GW4064 attenuated the expression of CFTR Cl^- channels, whereas inhibition of CFTR activity with either CFTR-_inh-172 (10 µM) or GlyH-101 (25 µM) also prevented wound healing. Promoter/reporter assays revealed that FXR-induced downregulation of CFTR is mediated at the transcriptional level. In contrast, UDCA (50-150 µM) enhanced wound healing in vitro and prevented the effects of DCA. Finally, DCA inhibited and UDCA promoted mucosal healing in an in vivo mouse model. In conclusion, these studies suggest bile acids are important regulators of epithelial wound healing and are therefore good targets for development of new drugs to modulate intestinal barrier function in disease treatment. NEW & NOTEWORTHY The secondary bile acid, deoxycholic acid, inhibits colonic epithelial wound healing, an effect which appears to be mediated by activation of the nuclear bile acid receptor, FXR, with subsequent downregulation of CFTR expression and activity. In contrast, ursodeoxycholic acid promotes wound healing, suggesting it may provide an alternative approach to prevent the losses of barrier function that are associated with mucosal inflammation in IBD patients.

Transcriptomic Landscape of Treatment-Naïve Ulcerative Colitis

BACKGROUND AND AIMS

Ulcerative colitis [UC] is a chronic inflammatory disease that effects the gastrointestinal tract and is considered one of the most prominent and common forms of inflammatory bowel disease [IBD]. This study aimed to define and describe the entire transcriptomic landscape in a well-stratified, treatment-naïve UC patient population compared with control patients by using next-generation technology, RNA-Seq.

METHODS

Mucosal biopsies from treatment-naïve UC patients [n = 14], and healthy controls [n = 16] underwent RNA-Seq. Principal component analysis [PCA], cell deconvolution methods, and diverse statistical methods were applied to obtain and characterise a dataset of significantly differentially expressed genes [DEGs].

RESULTS

Analyses revealed 1480 significantly DEGs in treatment-naïve UC when compared with controls. Cell populations of monocytes, T cells, neutrophils, B cells/ lymphoid cells, and myeloid cells were increased during inflammation, whereas the fraction of epithelial cells were reduced in UC, which is reflected by the DEGs; 79 DEGs were identified as IBD susceptibility genes, and 58 DEGs were expressed in a gender-specific manner. MUC5B, REG3A, DEFA5, and IL33 might be considered as colorectal cancer [CRC] risk factors following UC in males. AQP9 together with CLDN2 may have a role regulating tissue-specific physiological properties in tight junctions in UC. An additional functional role for AQP9 in the synthesis and/or the function of mucus can be implied.

CONCLUSIONS

This study reveals new potential players in UC pathogenesis in general, and provides evidence for a gender-dependent pathogenesis for UC. These results can be useful for the development of personalised treatment strategies for UC in the future.