Attenuated replication and damaging effects of SARS-CoV-2 Omicron variants in an intestinal epithelial barrier model.

Many COVID-19 patients suffer from gastrointestinal symptoms and impaired intestinal barrier function is thought to play a key role in Long COVID. Despite its importance, the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on intestinal epithelia is poorly understood. To address this, we established an intestinal barrier model integrating epithelial Caco-2 cells, mucus-secreting HT29 cells and Raji cells. This gut epithelial model allows efficient differentiation of Caco-2 cells into microfold-like cells, faithfully mimics intestinal barrier function, and is highly permissive to SARS-CoV-2 infection. Early strains of SARS-CoV-2 and the Delta variant replicated with high efficiency, severely disrupted barrier function, and depleted tight junction proteins, such as claudin-1, occludin, and ZO-1. In comparison, Omicron subvariants also depleted ZO-1 from tight junctions but had fewer damaging effects on mucosal integrity and barrier function. Remdesivir, the fusion inhibitor EK1 and the transmembrane serine protease 2 inhibitor Camostat inhibited SARS-CoV-2 replication and thus epithelial barrier damage, while the Cathepsin inhibitor E64d was ineffective. Our results support that SARS-CoV-2 disrupts intestinal barrier function but further suggest that circulating Omicron variants are less damaging than earlier viral strains.

Prediction of anastomotic insufficiency based on the mucosal microbiome prior to colorectal surgery: a proof-of-principle study.

Anastomotic leakage (AL) is a potentially life-threatening complication following colorectal cancer (CRC) resection. In this study, we aimed to unravel longitudinal changes in microbial structure before, during, and after surgery and to determine if microbial alterations may be predictive for risk assessment between sufficient anastomotic healing (AS) and AL prior surgery. We analysed the microbiota of 134 colon mucosal biopsies with 16S rRNA V1-V2 gene sequencing. Samples were collected from three location sites before, during, and after surgery, and patients received antibiotics after the initial collection and during surgery. The microbial structure showed dynamic surgery-related changes at different time points. Overall bacterial diversity and the abundance of some genera such as Faecalibacterium or Alistipes decreased over time, while the genera Enterococcus and Escherichia_Shigella increased. The distribution of taxa between AS and AL revealed significant differences in the abundance of genera such as Prevotella, Faecalibacterium and Phocaeicola. In addition to Phocaeicola, Ruminococcus2 and Blautia showed significant differences in abundance between preoperative sample types. ROC analysis of the predictive value of these genera for AL revealed an AUC of 0.802 (p = 0.0013). In summary, microbial composition was associated with postoperative outcomes, and the abundance of certain genera may be predictive of postoperative complications.

Intestinal organoids to model Salmonella infection and its impact on progenitors.

In order to survive and replicate, Salmonella has evolved mechanisms to gain access to intestinal epithelial cells of the crypt. However, the impact of Salmonella Typhimurium on stem cells and progenitors, which are responsible for the ability of the intestinal epithelium to renew and protect itself, remains unclear. Given that intestinal organoids growth is sustained by stem cells and progenitors activity, we have used this model to document the effects of Salmonella Typhimurium infection on epithelial proliferation and differentiation, and compared it to an in vivo model of Salmonella infection in mice. Among gut segments, the caecum was preferentially targeted by Salmonella. Analysis of infected crypts and organoids demonstrated increased length and size, respectively. mRNA transcription profiles of infected crypts and organoids pointed to upregulated EGFR-dependent signals, associated with a decrease in secretory cell lineage differentiation. To conclude, we show that organoids are suited to mimic the impact of Salmonella on stem cells and progenitors cells, carrying a great potential to drastically reduce the use of animals for scientific studies on that topic. In both models, the EGFR pathway, crucial to stem cells and progenitors proliferation and differentiation, is dysregulated by Salmonella, suggesting that repeated infections might have consequences on crypt integrity and further oncogenesis.

Fecal calprotectin and endoscopic scores: The cornerstones in clinical practice for evaluating mucosal healing in inflammatory bowel disease.

Managing inflammatory bowel disease (IBD) is becoming increasingly complex and personalized, considering the advent of new advanced therapies with distinct mechanisms of action. Achieving mucosal healing (MH) is a pivotal therapeutic goal in IBD management and can prevent IBD progression and reduce flares, hospitalization, surgery, intestinal damage, and colorectal cancer. Employing proactive disease and therapy assessment is essential to achieve better control of intestinal inflammation, even if subclinical, to alter the natural course of IBD. Periodic monitoring of fecal calprotectin (FC) levels and interval endoscopic evaluations are cornerstones for evaluating response/remission to advanced therapies targeting IBD, assessing MH, and detecting subclinical recurrence. Here, we comment on the article by Ishida et al Moreover, this editorial aimed to review the role of FC and endoscopic scores in predicting MH in patients with IBD. Furthermore, we intend to present some evidence on the role of these markers in future targets, such as histological and transmural healing. Additional prospective multicenter studies with a stricter MH criterion, standardized endoscopic and histopathological analyses, and virtual chromoscopy, potentially including artificial intelligence and other biomarkers, are desired.

Deoxycholic acid inducing chronic atrophic gastritis with colonic mucosal lesion correlated to mucosal immune dysfunction in rats.

The present study aimed to explore the underlying mechanism of bile reflux-inducing chronic atrophic gastritis (CAG) with colonic mucosal lesion. The rat model of CAG with colonic mucosal lesion was induced by free-drinking 20 mmol/L sodium deoxycholate to simulate bile reflux and 2% cold sodium salicylate for 12 weeks. In comparison to the control group, the model rats had increased abundances of Bacteroidetes and Firmicutes but had decreased abundances of Proteobacteria and Fusobacterium. Several gut bacteria with bile acids transformation ability were enriched in the model group, such as Blautia, Phascolarctobacter, and Enterococcus. The cytotoxic deoxycholic acid and lithocholic acid were significantly increased in the model group. Transcriptome analysis of colonic tissues presented that the down-regulated genes enriched in T cell receptor signaling pathway, antigen processing and presentation, Th17 cell differentiation, Th1 and Th2 cell differentiation, and intestinal immune network for IgA production in the model group. These results suggest that bile reflux-inducing CAG with colonic mucosal lesion accompanied by gut dysbacteriosis, mucosal immunocompromise, and increased gene expressions related to repair of intestinal mucosal injury.

[Correlations Between the Expression of MicroRNA-155 and Suppressor of Cytokine Signaling 1 in Colonic Mucosal Tissue and Disease Severity in Patients With Ulcerative Colitis].

Objective To explore the relationship between the expression levels of microRNA-155 (miR-155) and suppressor of cytokine signaling 1 (SOCS1) in the colonic mucosal tissue of patients with ulcerative colitis (UC) and the severity of the disease.Methods A total of 130 UC patients admitted to the Second Affiliated Hospital of Hebei North University from September 2021 to June 2023 were selected.According to the modified Mayo score system,the patients were assigned into an active stage group (n=85) and a remission stage group (n=45).According to the modified Truelove and Witts classification criteria,the UC patients at the active stage were assigned into a mild group (n=35),a moderate group (n=30),and a severe group (n=20).A total of 90 healthy individuals who underwent colonoscopy for physical examination or those who had normal colonoscopy results after single polypectomy and excluded other diseases were selected as the control group.The colonic mucosal tissues of UC patients with obvious lesions and the colonic mucosal tissue 20 cm away from the anus of the control group were collected.The levels of miR-155 and SOCS1 mRNA in tissues were determined by fluorescence quantitative PCR,and the expression of SOCS1 protein in tissues was determined by immunohistochemistry.The correlations of the levels of miR-155 and SOCS1 mRNA in the colonic mucosal tissue with the modified Mayo score of UC patients were analyzed.The values of the levels of miR-155 and SOCS1 mRNA in predicting the occurrence of severe illness in the UC patients at the active stage were evaluated.Results Compared with the control group and the remission stage group,the active stage group showed up-regulated expression level of miR-155,down-regulated level of SOCS1 mRNA,and decreased positive rate of SOCS1 protein in the colonic mucosal tissue (all P<0.001).The expression level of miR-155 and modified Mayo score in colonic mucosal tissues of UC patients at the active stage increased,while the mRNA level of SOCS1 was down-regulated as the disease evolved from being mild to severe (all P<0.001).The modified Mayo score was positively correlated with the miR-155 level and negative correlated with the mRNA level of SOCS1 in colonic mucosal tissues of UC patients (all P<0.001).The high miR-155 level (OR=2.762,95%CI=1.284-5.944,P=0.009),low mRNA level of SOCS1 (OR=2.617,95%CI=1.302-5.258,P=0.007),and modified Mayo score≥12 points (OR=3.232,95%CI=1.450-7.204,P=0.004) were all risk factors for severe disease in the UC patients at the active stage.The area under curve of miR-155 combined with SOCS1 mRNA in predicting severe illness in the UC patients at the active stage was 0.920.Conclusions The expression levels of miR-155 and SOCS1 mRNA were correlated with the disease severity in the UC patients at the active stage.The combination of the two indicators demonstrates good performance in predicting the occurrence of severe illness in UC patients at the active stage.

Interaction between inflammatory bowel disease, physical activity, and myokines: Assessment of serum irisin levels.

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, showed a wide spectrum of intestinal and extra-intestinal manifestations, which rendered the patients physically inactive and impaired their quality of life. It has been found that physical activity is a non-pharmacological intervention that improves the quality of life for those patients. Irisin is one member of the myokines secreted by muscle contraction during exercise and could be used as an anti-inflammatory biomarker in assessing the physical activity of IBD patients. In addition, experimental studies showed that exogenous irisin significantly decreased the inflammatory markers and the histological changes of the intestinal mucosa observed in experimental colitis. Furthermore, irisin produces changes in the diversity of the microbiota. Therefore, endogenous or exogenous irisin, via its anti-inflammatory effects, will improve the health of IBD patients and will limit the barriers to physical activity in patients with IBD.

Comprehensive analysis of disulfidptosis-related genes reveals the effect of disulfidptosis in ulcerative colitis.

Ulcerative colitis (UC) is a chronic inflammatory condition of the intestinal tract. Various programmed cell death pathways in the intestinal mucosa are crucial to the pathogenesis of UC. Disulfidptosis, a recently identified form of programmed cell death, has not been extensively reported in the context of UC. This study evaluated the expression of disulfidptosis-related genes (DRGs) in UC through public databases and assessed disulfide accumulation in the intestinal mucosal tissues of UC patients and dextran sulfate sodium (DSS)-induced colitis mice via targeted metabolomics. We utilized various bioinformatics techniques to identify UC-specific disulfidptosis signature genes, analyze their potential functions, and investigate their association with immune cell infiltration in UC. The mRNA and protein expression levels of these signature genes were confirmed in the intestinal mucosa of DSS-induced colitis mice and UC patients. A total of 24 DRGs showed differential expression in UC. Our findings underscore the role of disulfide stress in UC. Four UC-related disulfidptosis signature genes-SLC7A11, LRPPRC, NDUFS1, and CD2AP-were identified. Their relationships with immune infiltration in UC were analyzed using CIBERSORT, and their expression levels were validated by quantitative real-time PCR and western blotting. This study provides further insights into their potential functions and explores their links to immune infiltration in UC. In summary, disulfidptosis, as a type of programmed cell death, may significantly influence the pathogenesis of UC by modulating the homeostasis of the intestinal mucosal barrier.

Effects of High-Mobility Group Box-1 on Mucosal Immunity and Epithelial Differentiation in Colitic Carcinoma.

Abnormalities in mucosal immunity are involved in the onset and progression of ulcerative colitis (UC), resulting in a high incidence of colorectal cancer (CRC). While high-mobility group box-1 (HMGB1) is overexpressed during colorectal carcinogenesis, its role in UC-related carcinogenesis remains unclear. In the present study, we investigated the role of HMGB1 in UC-related carcinogenesis and sporadic CRC. Both the azoxymethane colon carcinogenesis and dextran sulfate sodium colitis carcinogenesis models demonstrated temporal increases in mucosal HMGB1 levels. Activated CD8+ cells initially increased and then decreased, whereas exhausted CD8+ cells increased. Additionally, we observed increased regulatory CD8+ cells, decreased naïve CD8+ cells, and decreased mucosal epithelial differentiation. In the in vitro study, HMGB1 induced energy reprogramming from oxidative phosphorylation to glycolysis in CD8+ cells and intestinal epithelial cells. Furthermore, in UC dysplasia, UC-related CRC, and hyperplastic mucosa surrounding human sporadic CRC, we found increased mucosal HMGB1, decreased activated CD8+ cells, and suppressed mucosal epithelial differentiation. However, we observed increased activated CD8+ cells in active UC mucosa. These findings indicate that HMGB1 plays an important role in modulating mucosal immunity and epithelial dedifferentiation in both UC-related carcinogenesis and sporadic CRC.

Metabolic Endotoxemia: From the Gut to Neurodegeneration.

Metabolic endotoxemia is a severe health problem for residents in developed countries who follow a Western diet, disrupting intestinal microbiota and the whole organism's homeostasis. Although the effect of endotoxin on the human immune system is well known, its long-term impact on the human body, lasting many months or even years, is unknown. This is due to the difficulty of conducting in vitro and in vivo studies on the prolonged effect of endotoxin on the central nervous system. In this article, based on the available literature, we traced the path of endotoxin from the intestines to the blood through the intestinal epithelium and factors promoting the development of metabolic endotoxemia. The presence of endotoxin in the bloodstream and the inflammation it induces may contribute to lowering the blood-brain barrier, potentially allowing its penetration into the central nervous system; although, the theory is still controversial. Microglia, guarding the central nervous system, are the first line of defense and respond to endotoxin with activation, which may contribute to the development of neurodegenerative diseases. We traced the pro-inflammatory role of endotoxin in neurodegenerative diseases and its impact on the epigenetic regulation of microglial phenotypes.

Ambient Particulate Matter Induces In Vitro Toxicity to Intestinal Epithelial Cells without Exacerbating Acute Colitis Induced by Dextran Sodium Sulfate or 2,4,6-Trinitrobenzenesulfonic Acid.

Inflammatory bowel disease (IBD) is an immunologically complex disorder involving genetic, microbial, and environmental risk factors. Its global burden has continued to rise since industrialization, with epidemiological studies suggesting that ambient particulate matter (PM) in air pollution could be a contributing factor. Prior animal studies have shown that oral PM10 exposure promotes intestinal inflammation in a genetic IBD model and that PM2.5 inhalation exposure can increase intestinal levels of pro-inflammatory cytokines. PM10 and PM2.5 include ultrafine particles (UFP), which have an aerodynamic diameter of <0.10 µm and biophysical and biochemical properties that promote toxicity. UFP inhalation, however, has not been previously studied in the context of murine models of IBD. Here, we demonstrated that ambient PM is toxic to cultured Caco-2 intestinal epithelial cells and examined whether UFP inhalation affected acute colitis induced by dextran sodium sulfate and 2,4,6-trinitrobenzenesulfonic acid. C57BL/6J mice were exposed to filtered air (FA) or various types of ambient PM reaerosolized in the ultrafine size range at ~300 µg/m3, 6 h/day, 3-5 days/week, starting 7-10 days before disease induction. No differences in weight change, clinical disease activity, or histology were observed between the PM and FA-exposed groups. In conclusion, UFP inhalation exposure did not exacerbate intestinal inflammation in acute, chemically-induced colitis models.

Morphological Characteristics of Colon Tumors in Mice with Different Tolerance to Hypoxia.

In adult male C57BL/6 mice with high (HR) and low (LR) resistance to hypoxia, morphological features of colon tumors and blood parameters were evaluated 70 days after intraperitoneal injection of azoxymethane and subsequent consumption of 3 cycles of dextran sulfate sodium. On macroscopic analysis, tumors were found in the distal colon in 35% (7 of 20 animals) of HR and 31% (4 of 13 animals) of LR animals. Microscopic analysis of the distal colon revealed tumors in 75% (15 of 20 animals) of HR and 69% (9 of 13 animals) of LR mice. The tumors were presented by areas of glandular intraepithelial neoplasia and adenocarcinomas; the incidence and the area of the tumors did not differ in groups of HR and LR mice. The number of neuroendocrine and goblet cells in the distal colon mucosa in the areas of tumors was similar in the compared groups. However, in both HR and LR mice of the experimental groups, the content of goblet cells in tumors was lower and the content of endocrine cells was higher than in the corresponding control groups. In the peripheral blood, the erythrocyte count and hemoglobin content decreased in HR and LR mice of the experimental groups; the relative number of monocytes increased only in HR mice and the absolute number of lymphocytes and monocytes decreased in LR mice. Thus, 70 days after azoxymethane administration and dextran sulfate sodium consumption, the tumors in mice were presented by glandular intraepithelial neoplasia and adenocarcinomas, and their incidence and area did not differ between animals with different tolerance to hypoxia.

Fibrogenesis in Human Mucosa and Muscularis Precision-Cut Intestinal Slices.

In Crohn's Disease (CD), intestinal fibrosis is a prevalent yet unresolved complication arising from chronic and transmural inflammation. The histological assessment of CD intestines shows changes in tissue morphology in all the layers, including the mucosa and muscularis. This study aimed to determine the differences in fibrogenesis between mucosa and muscularis. Human precision-cut intestinal slices (hPCIS) were prepared from human intestine mucosa and muscularis and treated with TGF-ß1 and/or PDGF-BB for 72 h. Gene and protein expression and matrix metalloproteinase (MMP) activity were determined. The basal gene expression of various fibrosis markers was higher in muscularis compared to mucosa hPCIS. During incubation, Pro-Collagen-1A1 secretion increased in muscularis but not in mucosa hPCIS. MMP gene expression increased during incubation in mucosa and muscularis hPCIS, except for MMP9, MMP12, and MMP13 in muscularis hPCIS. Incubation with TGF-ß1 caused increased COL1A1 expression in the mucosa but not in muscularis hPCIS. In muscularis hPCIS, TGF-ß1 treatment caused a decrease in MMP1 and CTSK expression, while MMP13 was increased. In the presence of TGF-ß1, protease inhibitor expression was stable, except for SERPINE1, which was increased in muscularis hPCIS. We conclude that fibrogenesis is more pronounced in muscularis hPCIS compared to mucosa hPCIS, especially when stimulated with TGF-ß1.

The Barrier Disruption and Pyroptosis of Intestinal Epithelial Cells Caused by Perfringolysin O (PFO) from Clostridium perfringens.

Clostridium perfringens (C. perfringens), a Gram-positive bacterium, produces a variety of toxins and extracellular enzymes that can lead to disease in both humans and animals. Common symptoms include abdominal swelling, diarrhea, and intestinal inflammation. Severe cases can result in complications like intestinal hemorrhage, edema, and even death. The primary toxins contributing to morbidity in C. perfringens-infected intestines are CPA, CPB, CPB2, CPE, and PFO. Amongst these, CPB, CPB2, and CPE are implicated in apoptosis development, while CPA is associated with cell death, increased intracellular ROS levels, and the release of the inflammatory factor IL-18. However, the exact mechanism by which PFO toxins exert their effects in the infected gut is still unidentified. This study demonstrates that a C. perfringens PFO toxin infection disrupts the intestinal epithelial barrier function through in vitro and in vivo models. This study emphasizes the notable influence of PFO toxins on intestinal barrier integrity in the context of C. perfringens infections. It reveals that PFO toxins increase ROS production by causing mitochondrial damage, triggering pyroptosis in IPEC-J2 cells, and consequently resulting in compromised intestinal barrier function. These results offer a scientific foundation for developing preventive and therapeutic approaches against C. perfringens infections.

Ginkgetin improved experimental colitis by inhibiting intestinal epithelial cell apoptosis through EGFR/PI3K/AKT signaling.

Excessive apoptosis of intestinal epithelial cells leads to intestinal barrier dysfunction, which is not only one of the pathological features of inflammatory bowel disease (IBD) but also a therapeutic target. A natural plant extract, Ginkgetin (GK), has been reported to have anti-apoptotic activity, but its role in IBD is unknown. This study aimed to explore whether GK has anti-colitis effects and related mechanisms. An experimental colitis model induced by dextran sulfate sodium (DSS) was established, and GK was found to relieve colitis in DSS-induced mice as evidenced by improvements in weight loss, colon shortening, Disease Activity Index (DAI), macroscopic and tissue scores, and proinflammatory mediators. In addition, in DSS mice and TNF-α-induced colonic organoids, GK protected the intestinal barrier and inhibited intestinal epithelial cell apoptosis, by improving permeability and inhibiting the number of apoptotic cells and the expression of key apoptotic regulators (cleaved caspase 3, Bax and Bcl-2). The underlying mechanism of GK's protective effect was explored by bioinformatics, rescue experiments and molecular docking, and it was found that GK might directly target and activate EGFR, thereby interfering with PI3K/AKT signaling to inhibit apoptosis of intestinal epithelial cells in vivo and in vitro. In conclusion, GK inhibited intestinal epithelial apoptosis in mice with experimental colitis, at least in part, by activating EGFR and interfering with PI3K/AKT activation, explaining the underlying mechanism for ameliorating colitis, which may provide new options for the treatment of IBD.

Azoxymethane-induced carcinogenesis-like model of mouse intestine and mouse embryonic stem cell-derived intestinal organoids.

BACKGROUND: Tumor modeling using organoids holds potential in studies of cancer development, enlightening both the intracellular and extracellular molecular mechanisms behind different cancer types, biobanking, and drug screening. Intestinal organoids can be generated in vitro using a unique type of adult stem cells which are found at the base of crypts and are characterized by their high Lgr5 expression levels. METHODS AND RESULTS: In this study, we successfully established intestinal cancer organoid models by using both the BALB/c derived and mouse embryonic stem cells (mESCs)-derived intestinal organoids. In both cases, carcinogenesis-like model was developed by using azoxymethane (AOM) treatment. Carcinogenesis-like model was verified by H&E staining, immunostaining, relative mRNA expression analysis, and LC/MS analysis. The morphologic analysis demonstrated that the number of generated organoids, the number of crypts, and the intensity of the organoids were significantly augmented in AOM-treated intestinal organoids compared to non-AOM-treated ones. Relative mRNA expression data revealed that there was a significant increase in both Wnt signaling pathway-related genes and pluripotency transcription factors in the AOM-induced intestinal organoids. CONCLUSION: We successfully developed simple carcinogenesis-like models using mESC-based and Lgr5 + stem cell-based intestinal organoids. Intestinal organoid based carcinogenesi models might be used for personalized cancer therapy in the future.

Single cell transcriptomic analysis of the canine duodenum in chronic inflammatory enteropathy and health.

Chronic inflammatory enteropathy (CIE) is a common condition in dogs causing recurrent or persistent gastrointestinal clinical signs. Pathogenesis is thought to involve intestinal mucosal inflammatory infiltrates, but histopathological evaluation of intestinal biopsies from dogs with CIE fails to guide treatment, inform prognosis, or correlate with clinical remission. We employed single-cell RNA sequencing to catalog and compare the diversity of cells present in duodenal mucosal endoscopic biopsies from 3 healthy dogs and 4 dogs with CIE. Through characterization of 35,668 cells, we identified 31 transcriptomically distinct cell populations, including T cells, epithelial cells, and myeloid cells. Both healthy and CIE samples contributed to each cell population. T cells were broadly subdivided into GZMAhigh (putatively annotated as tissue resident) and IL7Rhigh (putatively annotated as non-resident) T cell categories, with evidence of a skewed proportion favoring an increase in the relative proportion of IL7Rhigh T cells in CIE dogs. Among the myeloid cells, neutrophils from CIE samples exhibited inflammatory (SOD2 and IL1A) gene expression signatures. Numerous differentially expressed genes were identified in epithelial cells, with gene set enrichment analysis suggesting enterocytes from CIE dogs may be undergoing stress responses and have altered metabolic properties. Overall, this work reveals the previously unappreciated cellular heterogeneity in canine duodenal mucosa and provides new insights into molecular mechanisms which may contribute to intestinal dysfunction in CIE. The cell type gene signatures developed through this study may also be used to better understand the subtleties of canine intestinal physiology in health and disease.

Slit2-Robo4 signal pathway and tight junction in intestine mediate LPS-induced inflammation in mice.

BACKGROUND: Sepsis is one of the most common clinical diseases, which is characterized by a serious and uncontrollable inflammatory response. LPS-induced inflammation is a critical pathological event in sepsis, but the underlying mechanism has not yet been fully elucidated. METHODS: The animal model was established for two batches. In the first batch of experiments, Adult C57BL/6J mice were randomly divided into control group and LPS (5 mg/kg, i.p.)group . In the second batch of experiments, mice were randomly divided into control group, LPS group, and LPS+VX765(10 mg/kg, i.p., an inhibitor of NLRP3 inflammasome) group. After 24 hours, mice were anesthetized with isoflurane, blood and intestinal tissue were collected for tissue immunohistochemistry, Western blot analysis and ELISA assays. RESULTS: The C57BL/6J mice injected with LPS for twenty-four hours could exhibit severe inflammatory reaction including an increased IL-1ß, IL-18 in serum and activation of NLRP3 inflammasome in intestine. The injection of VX765 could reverse these effects induced by LPS. These results indicated that the increased level of IL-1ß and IL-18 in serum induced by LPS is related to the increased intestinal permeability and activation of NLRP3 inflammasome. In the second batch of experiments, results of western blot and immunohistochemistry showed that Slit2 and Robo4 were significant decreased in intestine of LPS group, while the expression of VEGF was significant increased. Meanwhile, the protein level of tight junction protein ZO-1, occludin, and claudin-5 were significantly lower than in control group, which could also be reversed by VX765 injection. CONCLUSIONS: In this study, we revealed that Slit2-Robo4 signaling pathway and tight junction in intestine may be involved in LPS-induced inflammation in mice, which may account for the molecular mechanism of sepsis.

Intestinal mRNA expression profiles associated with mucosal healing in ustekinumab-treated Crohn's disease patients: bioinformatics analysis and prospective cohort validation.

BACKGROUND: Variations exist in the response of patients with Crohn's disease (CD) to ustekinumab (UST) treatment, but the underlying cause remains unknown. Our objective was to investigate the involvement of immune cells and identify potential biomarkers that could predict the response to interleukin (IL) 12/23 inhibitors in patients with CD. METHODS: The GSE207022 dataset, which consisted of 54 non-responders and 9 responders to UST in a CD cohort, was analyzed. Differentially expressed genes (DEGs) were identified and subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Least absolute shrinkage and selection operator (LASSO) regression was used to screen the most powerful hub genes. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the predictive performances of these genes. Single-sample Gene Set Enrichment Analysis (ssGSEA) was used to estimate the proportions of immune cell types. These significantly altered genes were subjected to cluster analysis into immune cell-related infiltration. To validate the reliability of the candidates, patients prescribed UST as a first-line biologic in a prospective cohort were included as an independent validation dataset. RESULTS: A total of 99 DEGs were identified in the integrated dataset. GO and KEGG analyses revealed significant enrichment of immune response pathways in patients with CD. Thirteen genes (SOCS3, CD55, KDM5D, IGFBP5, LCN2, SLC15A1, XPNPEP2, HLA-DQA2, HMGCS2, DDX3Y, ITGB2, CDKN2B and HLA-DQA1), which were primarily associated with the response versus nonresponse patients, were identified and included in the LASSO analysis. These genes accurately predicted treatment response, with an area under the curve (AUC) of 0.938. T helper cell type 1 (Th1) cell polarization was comparatively strong in nonresponse individuals. Positive connections were observed between Th1 cells and the LCN2 and KDM5D genes. Furthermore, we employed an independent validation dataset and early experimental verification to validate the LCN2 and KDM5D genes as effective predictive markers. CONCLUSIONS: Th1 cell polarization is an important cause of nonresponse to UST therapy in patients with CD. LCN2 and KDM5D can be used as predictive markers to effectively identify nonresponse patients. TRIAL REGISTRATION: Trial registration number: NCT05542459; Date of registration: 2022-09-14; URL: https://www. CLINICALTRIALS: gov .

Intestinal Epithelial Creatine Transporter SLC6A8 Dysregulation in Inflammation and in Response to Adherent Invasive E. coli Infection.

Creatine transporter (CrT1) mediates cellular uptake of creatine (Cr), a nutrient pivotal in maintaining energy homeostasis in various tissues including intestinal epithelial cells (IECs). The impact of CrT1 deficiency on the pathogenesis of various psychiatric and neurological disorders has been extensively investigated. However, there are no studies on its regulation in IECs in health and disease. Current studies have determined differential expression of CrT1 along the length of the mammalian intestine and its dysregulation in inflammatory bowel disease (IBD)-associated inflammation and Adherent Invasive E. coli (AIEC) infection. CrT1 mRNA and protein levels in normal intestines and their alterations in inflammation and following AIEC infection were determined in vitro in model IECs (Caco-2/IEC-6) and in vivo in SAMP1/YitFc mice, a model of spontaneous ileitis resembling human IBD. CrT1 is differentially expressed in different regions of mammalian intestines with its highest expression in jejunum. In vitro, CrT1 function (Na+-dependent 14C-Cr uptake), expression and promoter activity significantly decreased following TNFα/IL1ß treatments and AIEC infection. SAMP1 mice and ileal organoids generated from SAMP1 mice also showed decreased CrT1 mRNA and protein compared to AKR controls. Our studies suggest that Cr deficiency in IECs secondary to CrT1 dysregulation could be a key factor contributing to IBD pathogenesis.