Colonic Barrier Research Articles

Embryonic exposure to 6:2 fluorotelomer alcohol mediates autism spectrum disorder-like behavior by dysfunctional microbe-gut-brain axis in mice

6:2 fluorotelomer alcohol (6:2 FTOH) is considered an emerging contaminant as a substitute for perfluoroalkyl and polyfluoroalkyl substances. Autism spectrum disorder (ASD) is a highly heterogeneous childhood neurodevelopmental disorder, the prevalence of which has been significantly increasing globally, possibly due to rising exposure to environmental pollutants. Additionally, the microbe-gut-brain axis plays a crucial role in the development of ASD. The purpose of study was to investigate the impact of embryonic 6:2 FTOH exposure on neurological development in mice and explore the potential involvement of the microbe-gut-brain. Pregnant mice were orally administered 6:2 FTOH from gestation day 8.5 until delivery, and follow-up testing was performed on day 22 post-delivery. The findings revealed that embryonic exposure to 6:2 FTOH led to ASD-like symptoms, cortical neuron apoptosis, glial cell activation, and abnormal synapse formation in mice. Furthermore, impairment of colonic barrier function, inflammatory response, and dysbiosis in gut microbiota were observed. Interestingly, supplementation with Lactobacillus rhamnosus GG during embryonic development mitigated these adverse outcomes. This study enhances our understanding of how environmental pollutants can impact neurological development in children and provides valuable insights for clinical prevention, diagnosis, and treatment strategies for non-genetic ASD.

Long term Coptidis Rhizoma intake induce gastrointestinal emptying inhibition and colon barrier weaken via bitter taste receptors activation in mice

BackgroundCoptidis Rhizoma, a classic bitter traditional Chinese medicine, can lead to digestive dysfunction when long-term use according to traditional experience. Bitter taste receptors have been found to regulate gastrointestinal smooth muscle contraction. Coptidis Rhizoma alkaloids are potential agonists for bitter taste receptors, but whether they can induce gastrointestinal dysfunction via bitter taste receptors is not clear. PurposeThe purpose of this study is to elucidate whether long-term Coptidis Rhizoma decoction/berberine intake can affect gastrointestinal function via bitter taste receptors. MethodsFirstly, mice were orally administered Coptidis Rhizoma decoction (or berberine) for 8 weeks, then their appetite, gastrointestinal emptying function, colon barrier function, and gut microbiota homeostasis were evaluated. Subsequently, isolated intestine, molecular docking, calcium release, and immunofluorescence co-localization experiments were applied to explore the mechanism of Coptidis Rhizoma decoction (or berberine) inhibition effects on gastrointestinal motility. Finally, transmembrane resistance, scratch assay, tight junction and cytoskeletal protein immunofluorescence staining were conducted to verify that the bitter taste receptor is the target for Coptidis Rhizoma decoction (or berberine) to damage the colon barrier function. ResultLong-term Coptidis Rhizoma decoction (or berberine) intake can reduce appetite, inhibit gastrointestinal contractions, disrupt bacterial balance and colon barrier function in mice. Further mechanistic studies have shown that the alkaloids of Coptidis Rhizoma are agonists for bitter taste receptors, which can promote α-gustducin binding to CHRM3 by activating bitter taste receptors, finally inhibiting gastrointestinal smooth muscle contraction. In addition, Coptidis Rhizoma decoction (or berberine) can activate bitter taste receptors and its downstream pathways PKCβ/RhoA/ROCK1/MLC-2, reshape skeletal proteins, downregulate tight junction protein expression, and ultimately disrupt colon barrier function. ConclusionsLong term Coptidis Rhizoma intake induce gastrointestinal emptying inhibition and colon barrier weaken via bitter taste receptor activation in mice.

Regulation of Isoleucine on Colonic Barrier Function in Rotavirus-Infected Weanling Piglets and Analysis of Gut Microbiota and Metabolomics

Regulation of Isoleucine on Colonic Barrier Function in Rotavirus-Infected Weanling Piglets and Analysis of Gut Microbiota and Metabolomics

Sanguinarine chloride hydrate mitigates colitis symptoms in mice through the regulation of the intestinal microbiome and metabolism of short-chain fatty acids

Sanguinarine constitutes the main components of Macleaya cordata, and exhibits diverse biological and pharmacological activities. This study investigated the effects of sanguinarine chloride hydrate (SGCH) on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) mice. Five groups were designed to investigate the effects of SGCH on the pathological symptoms, the mRNA expression levels of inflammatory cytokines, colonic mucosal barrier damage, microbiota composition, and SCFAs metabolism in UC mice. The administration of SGCH in DSS-induced UC mice resulted in the amelioration of pathological symptoms, as evidenced by an increase in body weight, a decrease in disease activity index score, elongation of colon length, reduction in spleen index, and improvement in colon injury. SGCH can regulate the expression of inflammatory cytokines (IL-6, TNF-α, IL-1β and IL-10) and tight junction proteins (ZO-1 and Occludin) associated with UC. SGCH exhibited a significant decrease in NF-κB P65 mRNA expression levels, accompanied by a significantly reduced protein level of NF-κB P-P65/P65. Further studies revealed SGCH effectively reversed the decrease in intestinal microbiota diversity induced by UC, thereby promoting the growth of beneficial bacteria such as Akkermansia, Alistipes, and norank_o_Clostridia_UCG-014. Correlation analysis demonstrated a positive association between butanoic acid, propanoic acid, isobutyric acid, isovaleric acid, valeric acid, hexanoic acid with Colidextribacter, while Coriobacteriaceae_UCG-002 exhibited a negative correlation with butanoic acid, acetic acid and propanoic acid. In conclusion, the administration of SGCH can ameliorate clinical symptoms in UC mice, regulate the expression of inflammatory cytokines and tight junction proteins, modulate intestinal microbiota metabolism and SCFAs production.

A Small Intestinal Helminth Infection Alters Colonic Mucus and Shapes the Colonic Mucus Microbiome.

Infecting humans with controlled doses of small intestinal helminths, such as human hookworm, is proposed as a therapy for the colonic inflammatory disease ulcerative colitis. Strengthening the colonic mucus barrier is a potential mechanism by which small intestinal helminths could treat ulcerative colitis. In this study, we compare C57BL/6 mice infected with the small intestinal helminth Heligmosomoides polygyrus and uninfected controls to investigate changes in colonic mucus. Histology, gene expression, and immunofluorescent analysis demonstrate that this helminth induces goblet cell hyperplasia, and an upregulation of mucin sialylation, and goblet-cell-derived functional proteins resistin-like molecule-beta (RELM-β) and trefoil factors (TFFs), in the colon. Using IL-13 knockout mice, we reveal that these changes are predominantly IL-13-dependent. The assessment of the colonic mucus microbiome demonstrates that H. polygyrus infection increases the abundance of Ruminococcus gnavus, a commensal bacterium capable of utilising sialic acid as an energy source. This study also investigates a human cohort experimentally challenged with human hookworm. It demonstrates that TFF blood levels increase in individuals chronically infected with small intestinal helminths, highlighting a conserved mucus response between humans and mice. Overall, small intestinal helminths modify colonic mucus, highlighting this as a plausible mechanism by which human hookworm therapy could treat ulcerative colitis.

Is Butyrate Concentration in the Equine Gastrointestinal Tract Altered During and After Surgery for Treatment of Large Colon Obstruction?

A major cause of morbidity and mortality in horses with large colon obstructive lesions is injury to the colonic mucosal barrier from ischemic injury. Since butyrate has been shown to play a critical role in the maintenance of a healthy mucosal barrier, it may play a role in the recovery process. This study's objective was to determine whether the differences in butyrate concentrations existed between horses with surgical large colon obstructive lesions and healthy horses both during and after surgery. Eleven horses presenting with surgical colic lesions were enrolled; colonic samples were acquired during surgery, and fecal samples were obtained 36 h later. Colonic and fecal samples were also obtained from control groups. Samples were analyzed for butyrate, acetate, and propionate concentrations. There was no significant difference in butyrate content between surgical colonic or fecal samples and controls; however, an alteration in the proportion of SCFAs in relation to one another was noted. These changes in the individual SCFA levels were not statistically significant. The study findings demonstrated that there were no significant differences in butyrate proportions when comparing samples from horses with surgical colic lesions to healthy control horses.

Folic acid-based hydrogels co-assembled with protocatechuic acid for enhanced treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) presents a significant therapeutic challenge due to the need for oral drug delivery systems that withstand acidic environment of stomach while effectively targeting intestinal inflammation. To address this issue, we created a novel hydrogel system based on a folic acid (FA)-dopamine (DA) conjugate, co-assembled with protocatechuic acid (PCA), to form F-DP hydrogels. These hydrogels demonstrated robust anti-gastric acid, mucosal adhesive, and injectable properties, enhancing their efficacy for targeted delivery. In DSS-induced colitis mouse models, treatment with F-DP hydrogels resulted in significant therapeutic improvements, including increased body weight, reduced disease activity index (DAI), and maintained colon length. Biochemical assays revealed that F-DP hydrogels significantly enhanced antioxidant enzyme activities (GSH and SOD) and reduced oxidative stress markers (NO and MDA). Histological assessments confirmed effective repair of the colonic mucosal barrier, restoration of tight junction protein ZO-1, and reduction of inflammatory lesions. Furthermore, immunofluorescence staining indicated that F-DP hydrogels facilitated macrophages polarization from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype, thereby reducing inflammation and promoting tissue repair. Our study demonstrates that F-DP hydrogels show significant potential for improving IBD treatment through enhanced gastric resistance, intestinal adhesion, and synergistic anti-inflammatory effects, warranting further investigation for clinical applications.

Biased constitutive signalling of the G protein-coupled receptor GPR35 suppresses gut barrier permeability

Agonist-independent, or constitutive, activity is an integral feature of G protein-coupled receptors but its relevance in patho-physiological settings is generally poorly explored. GPR35 is a therapeutic target in inflammatory diseases of the lower gut. In colonic organoids from a human GPR35a-expressing transgenic mouse line the GPR35 inverse agonist CID-2745687 increased barrier permeability substantially, indicating that constitutive receptor activity contributes to maintaining epithelial barrier integrity. High constitutive activity of GPR35 was also observed in both HT-29 and HEPG2 cells that express GPR35 endogenously. Mechanistic investigations in recombinant in vitro systems revealed that constitutive activity of GPR35a was biased and not equivalent across signalling pathways. Hence, no constitutive interactions of the receptor with arrestin-adaptor proteins or activation of Gαo-containing G protein heterotrimers were detected whilst, even at low GPR35a expression levels, substantial constitutive activation of heterotrimers containing either Gα12 or Gα13 was observed. Similar biased constitutive activity was observed for the human GPR35b isoform. The extent of constitutive and agonist-mediated activity was dependent on receptor expression level. At high receptor levels constitutive activation of Gα12 or Gα13 masked any agonist-induced effects whilst low expression levels with low constitutive activity allowed measurement of agonist-induced responses. These results highlight roles, selectivity and the extent of constitutive activity of GPR35 in cells and tissues that express this receptor endogenously and highlight the contribution of its constitutive activity to maintaining the colonic epithelial barrier, potentially limiting the development of inflammatory bowel diseases.

Dietary ω-3 Fatty Acids Mitigate Intestinal Barrier Integrity Alterations in Mice Fed a High-Fat Diet: Implications for Pancreatic Carcinogenesis

BackgroundAlthough body fatness is a recognized risk factor for pancreatic ductal adenocarcinoma (PDAC), the underlying mechanisms of how fat composition affects pancreatic carcinogenesis are poorly understood. High-fat diets (HFDs) can disrupt intestinal barrier function, potentially accelerating carcinogenesis. Omega-3 (ω-3) polyunsaturated fatty acids (FAs) have anti-inflammatory properties and help preserve intestinal integrity. ObjectiveThe objective of this study was to evaluate how ω-3 FAs affect the colonic barrier in the context of HFD-induced changes, in a mouse model of PDAC [p48-Cre; LSL-KrasG12D (KC)]. MethodsMale and female KC mice were randomly assigned into 1 of the following 4 groups: 1) a control diet containing ∼11% total calories from fat with an ω-6:ω-3 FA ratio of 10:1 (C), 2) the control diet with high concentrations of ω-3 FA with an ω-6:ω-3 FA ratio of 1:1 (Cω3), 3) an HFD containing 60% total calories from fat with an ω-6:ω-3 FA ratio of approximately 10:1 (HF), and 4) an HFD with high concentrations of ω-3 FA with an ω-6:ω-3 FA ratio of 1:1 (HFω3). ResultsConsumption of an HFD for 8 wk caused: 1) disruption of tight junction structure and function; 2) decreased goblet cell number; 3) higher colonic Toll-like receptor 4 (TLR4) and NADPH oxidase 1 expression; 4) activation of TLR4-triggered pathways, that is, NF-κB, c-Jun N-terminal kinase; 5) elevated plasma lipopolysaccharide concentrations; and 6) higher pancreatic TLR4 expression, and 7) accelerated acinar-to-ductal metaplasia. All of these events were mitigated in mice fed the HFω3. ConclusionsOur findings support the concept that, in the context of obesity, ω-3 FAs have protective effects during early-stage pancreatic carcinogenesis through the regulation of intestinal permeability and endotoxemia.

Poria cocos polysaccharides alleviate dextran sulphate sodium-induced ulcerative colitis in mice by modulating intestinal inflammatory responses and microbial dysbiosis

Poria cocos polysaccharide (PCP), one of the main active components of P. cocos, is extensively used worldwide and exhibits strong pharmacological effects. However, whether PCP can attenuate inflammatory bowel disease remains unclear. In this study, we assessed the effects of PCP supplementation on dextran sulphate sodium (DSS)-induced ulcerative colitis (UC) in mice. We found that PCP supplementation mitigated UC symptoms in DSS-treated mice, as evidenced by reductions in body weight loss, colon length shortening and disease activity index score. Importantly, PCP supplementation enhanced colonic barrier integrity by increasing tight junction protein abundance and exerted anti-inflammatory effects by suppressing nuclear factor-κB (NF-κB) activation in DSS-treated mice. Furthermore, PCP supplementation reversed DSS-induced dysbiosis in colonic microbiota by increasing the colonic abundance of beneficial bacteria (e.g. Akkermansiaceae) and decreasing the colonic abundance of harmful bacteria (e.g. Erysipelotrichaceae) in DSS-treated mice. Although PCP supplementation failed to ameliorate DSS-induced UC in antibiotic-treated mice, faecal microbiota transplantation from PCP-administered mice ameliorated DSS-induced UC in antibiotic-treated mice. In summary, PCP alleviates UC in mice by attenuating intestinal inflammation via the inhibition of NF-κB activation and modulating the intestinal microbiota.

Correlation Between Regulation of Intestinal Flora by Danggui-Shaoyao-San and Improvement of Cognitive Impairment in Mice With Alzheimer's Disease.

The abnormal central glucose metabolism in Alzheimer's disease (AD) is related to the brain-gut axis. This study aims to explore the target of Danggui-Shaoyao-San (DSS) in improving cognitive impairment. This study analyzed the differences in mice intestinal flora by 16S rRNA sequencing. The cognitive protective effects of DSS were observed through the Morris water maze and the new object recognition. The mitigation effects of DSS on Aβ and p-tau, regulatory effects on glucose metabolism targets, and intestinal structure effects were observed through brain and colon slices staining. The differences in neural ultrastructure were compared by transmission electron microscopy. The results showed that DSS affected the composition of intestinal dominant bacteria and bacteria genera and regulated the abundance of intestinal bacteria in AD mice. DSS improved the behavior of AD mice, alleviated the deposition of AD pathological products in the brain and colon, regulated the expression of glycometabolism-related proteins, and improved the colon barrier structure and neural ultrastructure in the brain of mice with AD. Our findings suggest that DSS may affect AD central glucose metabolism and improve cognition by regulating the gut-brain axis.

Etiolated-green tea attenuates colonic barrier dysfunction and inflammation in high-fat diet-induced mice by modulating gut microbiota

Colonic barrier dysfunction and inflammation arising from dysbiosis gut microbiota (GM) are strongly associated with a high-fat diet (HFD). Yellow leaf green tea (YLGT), a novel variety of etiolated-green tea, improving the intestinal barrier and inflammation is related to the regulation of GM disorders. To explore the ameliorative mechanism of YLGT, mice were fed an HFD with or without YLGT at doses of 150, 300, and 450 mg kg−1 for 12 weeks. YLGT rectified the GM imbalance, enriched short-chain fatty acid (SCFA)-producing bacteria and gut SCFA contents, activated G protein-coupled receptors, inhibited TLR4/NF-κB signaling pathway, strengthened the tight junction, and repaired the damaged intestinal barrier. The fecal microbiota transplantation experiment further confirmed that the GM was a key element in the anti-obesity and anti-intestinal inflammation effect of YLGT. YLGT has great promise in attenuating obesity-induced intestinal dysfunction. This research provides novel insights into the new mechanism of YLGT on HFD-induced obesity.

Scutellarein ameliorates dextran sulfate sodium-induced ulcerative colitis by inhibiting colonic epithelial cell proinflammation and barrier disruption.

Scutellarein (Scu) is a natural occurring flavonoid found in multiple traditional Chinese medicines such as Oroxylum indicum (L.) Kurz and Scutellaria baicalensis, with various pharmacological activities including anti-inflammation, anti-oxidation and myocardial protection. Here, we investigated the therapeutic efficacy of Scu on ulcerative colitis (UC) and the underlying mechanism. Efficacy of Scu on UC was evaluated in dextran sulfate sodium (DSS) induced colitis mouse model. Inflammation in colonic tissues was assessed by myeloperoxidase activity assay and RT-qPCR. Barrier proteins expression was examined using immunostaining and Western blot. IL-1β-treated HT-29 cells was used for mechanical investigation. Gavage of Scu significantly decreased the DAI score, improved colon shortening, ameliorated the pathological score in DSS-treated mice with better efficacy than the positive drug, 5-aminosalicylic acid. Scu also inhibited the expression levels of cytokines (Il-1β, Tnf-α, Il-1α, Il-6, and Cxcl1) as well as barrier proteins (E-cadherin, Occludin, and ZO-1) in colon tissues of DSS mice. In intestinal epithelial HT-29 cells, Scu attenuated the IL-1β-downregulated expression levels of E-cadherin, occludin, and ZO-1, while reduced IL-1β-upregulated IL-6 and IL-8 mRNA levels. Moreover, Scu inhibited the phosphorylation and nuclear translocation of NF-κB and suppression of NF-κB phosphorylation abolished IL-1β-disrupted epithelial barrier integrity and IL-1β-upregulated proinflammatory mediators expression in HT-29 cells. These data demonstrate that Scu is an efficacious therapeutic agent to treat UC. Inhibition of inflammatory responses and maintenance of epithelial barrier integrity through NF-κB signaling pathway underlines Scu therapeutic effect on UC.

Lactobacillus reuteri or Lactobacillus rhamnosus GG intervention facilitates gut barrier function, decreases corticosterone and ameliorates social behavior in LPS-exposed offspring

Probiotic therapy with Lactobacillus reuteri and Lactobacillus rhamnosus (LGG) demonstrates potential as an adjunctive treatment for autism spectrum disorder (ASD). In a rat model of ASD induced by lipopolysaccharide (LPS) injection during pregnancy, we evaluated the effects of these probiotics on offspring. Administration of L. reuteri or LGG for three weeks post-birth improved social deficits and reduced anxiety in LPS-exposed rats. Additionally, probiotics significantly modified short-chain fatty acid profiles, increasing butyric acid levels and decreasing propionic acid levels. They also enhanced colonic barrier integrity by upregulating tight junction proteins, including ZO-1, Occludin, and Claudin4. RNA sequencing identified differential gene expression in pathways related to inflammation, the HPA axis, and reactive oxygen species metabolism, with NADPH oxidase 1 (NOX1) emerging as a crucial gene. Validation studies confirmed that Lactobacillus strains reduced inflammatory cytokines, inhibited corticosterone secretion, increased antioxidant levels, and suppressed the NF-κB/NOX1 pathway. In an H2O2-induced oxidative stress model using Caco-2 cells, pre-treatment with L. reuteri, LGG, or NF-κB inhibitors enhanced cellular antioxidants, inhibited NF-κB/NOX1 activation, and improved barrier function. Overall, L. reuteri and LGG administration improved social behavior, bolstered colonic barrier function, and mitigated HPA axis overactivation in LPS-exposed rats, while also alleviating oxidative stress in the colon and Caco-2 cells. These findings suggest that L. reuteri and LGG have substantial clinical potential for ASD treatment by targeting multiple pathophysiological mechanisms, including inflammation, HPA axis dysregulation, and oxidative stress, thereby presenting a promising adjunctive therapeutic strategy for enhancing social behavior and gut health in ASD.

Lipopolysaccharide-regulated RNF31/NRF2 axis in colonic epithelial cells mediates homeostasis of the intestinal barrier in ulcerative colitis

BackgroundAlthough previous studies have shown that the Ring Finger Protein 31 (RNF31) gene confers susceptibility to inflammatory disease and colorectal cancer, the exact function of this protein in ulcerative colitis (UC) has not been determined. MethodsA mouse dextran sulfate sodium (DSS)-induced experimental colitis model was used to study RNF31 and NRF2 in colitis. RNF31 silencing or overexpression in vitro was applied to address the role of RNF31 in colonic mucosal barrier damage. Immunohistochemistry and silico analysis was performed to investigate the expression of RNF31 via taking advantage of UC tissue samples and Gene Expression Omnibus (GEO) data, respectively. The cycloheximide (CHX)-chase experiment and Co-Immunoprecipitation (Co-IP) assays were conducted to explore the association of RNF31 protein with NRF2 and P62. ResultsRNF31 is highly expressed in UC patients, in inflamed murine colon induced DSS and Lipopolysaccharide (LPS)-treated epithelial cells, while the express of NRF2 was Tabdecreased. RNF31-knockdown mice in the DSS-induced colitis model had a less severe phenotype, which was associated with a more integrated barrier of colon epithelial cells. While depletion of NRF2 in colitis model exacerbated intestinal inflammation. Mechanistically, RNF31 promoted the degradation of NRF2 by regulating its ubiquitination. Upon stimulation by RNF31, NRF2 is K63 ubiquitinated, which is associated with the C871 residue of RNF31. Moreover, downregulated NRF2 mediates inflammation by promoting the secretion of IL1β and IL18, leading to damage of the intestinal barrier. Upon LPS stimulation, the interaction of the PUB domain of RNF31 with the UBA domain of P62 increased, resulting in decreased degradation of the RNF31 protein via autophagy. ConclusionOverall, depletion of RNF31 effectively relieves DSS-induced colitis in mice by inhibiting NRF2 degradation, suggesting that RNF31 may be a potential therapy for human ulcerative colitis.

The value of assessing deep disease healing by probe-based confocal laser endomicroscopy and histology for long-term prognosis of ulcerative colitis.

The benefits of deep disease healing need evaluation by long-term clinical research in different populations. Confocal laser endomicroscopy (CLE) is a superior method for evaluating deep disease healing. This prospective study enrolled ulcerative colitis (UC) patients in clinical remission who underwent colonoscopy, CLE, and histological assessment. Patients were monitored for relapse by patient-reported outcomes and colonoscopy evaluation of mucosal healing. The ability of different methods of mucosal healing to predict long-term disease recurrence was assessed using Kaplan-Meier estimation and Cox proportional hazard regression. Forty-two patients in clinical remission were assessed by colonoscopy. Those with Mayo endoscopic subscores (MES)≤1 were enrolled. The 48-month recurrence rates in present healing group, assessed by CLE (colonic barrier assessment and ENHANCE index) and by histological examination (Geboes scale), were 20.0%, 26.7%, and 11.1%, respectively, and were significantly lower than absent healing group (P<0.05). Univariate Cox proportional risk regression analysis in absent of healing disease, determined by the ENHANCE index and Geboes scale, indicated an increased risk of recurrent events, with hazard ratios (HR) of 3.87 (95% CI: 1.18, 12.62) and 8.20 (95% CI: 1.06, 63.30), respectively. Multivariate Cox proportional hazard regression analysis adjusted for the extent of inflammation (E3 or not) showed a significant difference only for the ENHANCE index, with an HR of 3.53 (95% CI: 1.03, 12.10), P=0.045. Deep disease healing has a lower recurrence rate. The colonic barrier healing assessment, ENHANCE index, and histological Geboes scale have superior long-term prognostic value for UC patients.

Didymin Ameliorates Dextran Sulfate Sodium (DSS)-Induced Ulcerative Colitis by Regulating Gut Microbiota and Amino Acid Metabolism in Mice.

Background: Didymin is a dietary flavonoid derived from citrus fruits and has been shown to have extensive biological functions, especially anti-inflammatory effects, but its mechanism is unclear. The purpose of this study was to investigate the potential mechanism of didymin that alleviates ulcerative colitis. Methods and Results: Our results indicated that didymin could alleviate the symptoms of ulcerative colitis, as it inhibited the expressions of interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Didymin also promoted the expressions of claudin-1 and zona occludens-1(ZO-1), which are closely related with restoring colon barrier function. Didymin also increased the abundance of Firmicutes and Verrucomicobiota, while decreasing the abundance of Bacteroidota and Proteobacteria. Meanwhile, didymin significantly altered the levels of metabolites related to arginine synthesis and metabolism, and lysine degradation in the colitis mice. Utilizing network pharmacology and molecular docking, our results showed that the metabolites L-ornithine and saccharin could interact with signal transducer and activator of transcription 3 (STAT3) and nuclear factor kappa-B (NF-κB). In this in vitro study, L-ornithine could reduce the expressions of transcription factors STAT3 and NF-κB, and it also inhibited the expressions of IL-6 and IL-1β in the lipopolysaccharides (LPS) induced in RAW264.7 cells, while saccharin had the opposite effect. Conclusions: Taken together, didymin can regulate gut microbiota and alter metabolite products, which can modulate STAT3 and NF-κB pathways and inhibit the expressions of inflammatory factors and inflammatory response in the DSS-induced colitis mice.

Human Amniotic Epithelial Stem Cells Promote Colonic Recovery in Experimental Colitis via Exosomal MiR-23a-TNFR1-NF-κB Signaling.

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, manifests as chronic intestinal inflammation with debilitating symptoms, posing a significant burden on global healthcare. Moreover, current therapies primarily targeting inflammation can lead to immunosuppression-related complications. Human amniotic epithelial stem cells (hAESCs), which exhibit low immunogenicity and ethical acceptability, have gained attention as potential therapeutics. In this study, it is demonstrated that their encapsulation in a hydrogel and administration via anal injection enhanced the colonic mucosal barrier repair in a murine colitis model induced by dextran sodium sulfate during the recovery phase. The underlying mechanism involved the release of exosomes from hAESCs enriched with microRNA-23a-3p, which post-transcriptionally reduced tumor necrosis factor receptor 1 expression, suppressing the nuclear factor-κB pathway in colonic epithelial cells, thus played a key role in inflammation. The novel approach shows potential for IBD treatment by restoring intestinal epithelial homeostasis without the immunosuppressive therapy-associated risks. Furthermore, the approach provides an alternative strategy to target the key molecular pathways involved in inflammation and promotes intestinal barrier function using hAESCs and their secreted exosomes. Overall, this study provides key insights to effectively treat IBD, addresses the unmet needs of patients, and reduces related healthcare burden.

Real meat shows good performance in maintaining colonic barrier function at a recommended amount of intake in mice

AbstractThis study aimed to investigate the effects and underlying mechanisms of real meat and plant‐based meat analogs on intestinal barrier function. Methods including PacBio sequencing, HPLC, histological observation, western blotting, and RT‐qPCR were jointly applied. The results indicated that the 20‐day intake of real meat and plant‐based meat analogs did not induce pathological changes in the colon of mice. However, when the feeding period was extended to 68 days, inflammatory infiltration was observed in the colon tissue of mice fed plant‐based meat analogs. In contrast, the intake of real meat for 68 days performed better in maintaining colonic barrier function by reducing cell apoptosis, increasing the number of goblet cells and mucin secretion, and upregulating the expression of tight junction proteins. High‐throughput sequencing revealed that the intake of real meat significantly altered the composition of the gut microbiota, reducing pro‐inflammatory bacteria (such as Bacteroides, Desulfovibrio, or Colidextribacter) or pathogenic bacteria (such as Mucispirillum and Helicobacter) while increasing beneficial bacteria (such as Lactobacillus, Bifidobacterium, or Roseburia). Additionally, the consumption of real meat markedly decreased protein fermentation in the colon, leading to lower levels of cadaverine, putrescine, and spermine. These changes associated with real meat consumption reduced the activation of the pro‐inflammatory pathway (lipopolysaccharide/Toll‐like receptor 4/nuclear factor kappa B), ultimately maintaining colonic homeostasis in mice. Collectively, the findings suggest that the proper intake of real meat is more beneficial for colon health in mice compared to plant‐based meat analogs.

BPP43_05035 is a Brachyspira pilosicoli cell surface adhesin that weakens the integrity of the epithelial barrier during infection

ABSTRACT The anaerobic spirochete Brachyspira causes intestinal spirochetosis, characterized by the intimate attachment of bacterial cells to the colonic mucosa, potentially leading to symptoms such as diarrhea, abdominal pain, and weight loss. Despite the clinical significance of Brachyspira infections, the mechanism of the interaction between Brachyspira and the colon epithelium is not known. We characterized the molecular mechanism of the B. pilosicoli-epithelium interaction and its impact on the epithelial barrier during infection. Through a proteomics approach, we identified BPP43_05035 as a candidate B. pilosicoli surface protein that mediates bacterial attachment to cultured human colonic epithelial cells. The crystal structure of BPP43_05035 revealed a globular lipoprotein with a six-bladed beta-propeller domain. Blocking the native BPP43_05035 on B. pilosicoli, either with a specific antibody or via competitive inhibition, abrogated its binding to epithelial cells, which required cell surface-exposed N-glycans. Proximity labeling and interaction assays revealed that BPP43_05035 bound to tight junctions, thereby increasing the permeability of the epithelial monolayer. Extending our investigation to humans, we discovered a downregulation of tight junction and brush border genes in B. pilosicoli-infected patients carrying detectable levels of epithelium-bound BPP43_05035. Collectively, our findings identify BPP43_05035 as a B. pilosicoli adhesin that weakens the colonic epithelial barrier during infection.