DSS-treated Mice Research Articles

Herba Origani alleviated DSS-induced ulcerative colitis in mice through remolding gut microbiota to regulate bile acid and short-chain fatty acid metabolisms

This study aimed to investigate the protective effect of Herba Origani, the dried whole herb of Origanum vulgare L., on dextran sodium sulfate (DSS)-induced ulcerative colitis in mice and explore its mechanisms of action through analyzing the intestinal microbiota in cecum contents and metabolites in colonic tissues. HOEP alleviated colitis symptoms, colonic inflammation and pathological injury as well as repaired intestinal barrier function in DSS-induced UC mice. The intestinal microbiota analysis showed that HOEP restored the gut microbiota dysbiosis in DSS-treated mice by increasing the alpha diversity of the intestinal microbiota, increasing the abundance of the Bacteroidota community and adjusting short-chain fatty acids (SCFAs), which maintain mucosal immunity and intestinal barrier. Metabolomic analysis revealed that HOEP promoted bile acids absorption and regulated bile acids metabolism in the intestine, thereby maintaining intestinal mucosal immune homeostasis. In addition, HOEP might also regulate the intestinal immune system through the phosphatidylinositol signaling system. These findings suggested that HOEP exerted promising protection against DSS-induced ulcerative mice through remolding gut microbiota to regulate bile acid and SCFA metabolism, and that HOEP have a potential to be utilized for the treatment of inflammatory intestinal diseases.

Fibroblasts overpressing WNT2b cause impairment of intestinal mucosal barrier

To investigate the mechanism by which fibroblasts with high WNT2b expression causes intestinal mucosa barrier disruption and promote the progression of inflammatory bowel disease (IBD). Caco-2 cells were treated with 20% fibroblast conditioned medium or co-cultured with fibroblasts highly expressing WNT2b, with the cells without treatment with the conditioned medium and cells co-cultured with wild-type fibroblasts as the control groups. The changes in barrier permeability of Caco-2 cells were assessed by measuring transmembrane resistance and Lucifer Yellow permeability. In Caco-2 cells co-cultured with WNT2b-overexpressing or control intestinal fibroblasts, nuclear entry of β-catenin was detected with immunofluorescence assay, and the expressions of tight junction proteins ZO-1 and E-cadherin were detected with Western blotting. In a C57 mouse model of dextran sulfate sodium (DSS)-induced IBD-like enteritis, the therapeutic effect of intraperitoneal injection of salinomycin (5 mg/kg, an inhibitor of WNT/β-catenin signaling pathway) was evaluated by observing the changes in intestinal inflammation and detecting the expressions of tight junction proteins. In the coculture system, WNT2b overexpression in the fibroblasts significantly promoted nuclear entry of β-catenin (P < 0.01) and decreased the expressions of tight junction proteins in Caco-2 cells; knockdown of FZD4 expression in Caco-2 cells obviously reversed this effect. In DSS-treated mice, salinomycin treatment significantly reduced intestinal inflammation and increased the expressions of tight junction proteins in the intestinal mucosa. Intestinal fibroblasts overexpressing WNT2b causes impairment of intestinal mucosal barrier function and can be a potential target for treatment of IBD.

Urokinase-type plasminogen activator blockade ameliorates experimental colitis in mice

Although several angiogenesis-related factors are reportedly involved in the pathogenesis of ulcerative colitis (UC), the mechanisms by which they contribute to disease are unclear. We first examined the expression of angiogenesis-related factors in inflamed colorectal tissue of UC patients using antibody array, and identified the 5 factors with highest expression, which included matrix metalloproteinase-8, urokinase-type plasminogen activator (uPA), angiostatin/plasminogen, hepatocyte growth factor and endoglin. Subsequent real-time PCR experiments using additional colorectal tissues revealed that uPA mRNA levels were significantly higher in inflamed tissues than in non-inflamed tissues, and significantly correlated with the severity of UC. Mirror section immunohistochemistry revealed that uPA was expressed in the neutrophils of inflamed colorectal tissues. We administered dextran sulfate sodium (DSS) in drinking water to uPA knockout (uPA−/−) mice, and found that the disease activity index in uPA-/- mice was marginally lower and the histological score in uPA−/− mice was significantly lower than those in wild-type mice, suggesting the importance of uPA in colitis. When an uPA-selective inhibitor, UK122, was administered to DSS-treated C57BL6J mice, the disease activity index and histological score in those mice were significantly lower compared with control mice. Multiple cytokine/chemokine assay using colorectal tissues from uPA−/− and UK122-treated mice revealed significantly lowered level of RANTES. In conclusion, uPA was highly expressed in neutrophils of the inflamed mucosa of UC patients, and the expression level correlated with the severity of UC. Genetic uPA deletion or pharmacological uPA blockade significantly ameliorated colitis in mice, concomitant with downregulation of RANTES.

Total flavone of flowers of Abelmoschus manihot (L.) Medic inhibits the expression of adhesion molecules in primary mesenteric arterial endothelial cells and ameliorates dextran sodium sulphate-induced ulcerative colitis in mice

BackgroundFlowers of Abelmoschus manihot (L.) medic (AM) is a traditional Chinese medicine used to treat chronic nephritis, nephrotic syndrome, diabetic nephropathy, and colonic inflammation. PurposeThis study aimed to explore the influence of the total flavone of AM flowers (TFA) on acute ulcerative colitis (UC) and the potential underlying mechanism. MethodsEfficacy of TFA (30, 60, 120 mg/kg) on UC was evaluated in a dextran sodium sulphate (DSS)-induced colonic inflammatory mouse model by analyzing disease activity index (DAI), histopathological score, colon length, and cytokine expression. Expression levels of critical adhesion molecules and nuclear factor kappa B (NF-κB) were examined by qRT-PCR, Western blotting, or immunofluorescence labeling. Myeloperoxidase activity was examined using ELISA. In vitro THP-1 adhesion assay was used to evaluate monocyte adhesion. ResultsTFA significantly reduced DAI score, prevented colon shortening, and ameliorated histological injuries of colons in DSS-treated mice. TFA inhibited the expression of cytokines (IL-1β and TNF-α) and adhesion molecules (ICAM-1, VCAM-1, and MAdCAM-1) in colon tissues of DSS mice. In vitro studies on mesenteric arterial endothelial cells (MAECs) showed that TFA attenuated TNF-α-induced upregulation of ICAM-1, VCAM-1, and MAdCAM-1, as well as THP-1 cell adhesion to MAECs. TFA also suppressed the phosphorylation and nuclear translocation of NF-κB in MAECs. ConclusionTFA efficaciously ameliorates UC possibly by inhibiting monocyte adhesion through blocking TNF-α-induced NF-κB activation, which in turn suppresses the upregulation of adhesive molecules in colon endothelial cells. Inhibiting the expression of adhesion molecule in MAECs may represent a useful strategy for therapeutic development to treat UC, with TFA being a safe and efficacious therapeutic agent.

Mixed Lactiplantibacillus plantarum strains alleviated DSS-induced intestinal inflammation of Balb/c mice via the 5-HT/5-HT7R/NF-κB signaling pathway

In this study, single and mixed Lactobacillus strains were orally administered to Balb/c mice with colitis induced by DSS to investigate the difference in anti-inflammatory activity between single and mixed Lactobacillus strains. Our data showed that the mixed Lactobacillus strains intervention significantly ameliorated the intestinal barrier disruption and colonic inflammation in the DSS-treated mice. Furthermore, mixedLactobacillusstrains intervention could alleviate intestinal flora dysbiosis of the mice. By measuring the fecal metabolites of the mice, Lactobacillusstrains were found to significantly affect linoleic acid and tryptophan metabolisms. Surprisingly, the single or mixed Lactobacillus significantly upregulated fecal serotonin levels and the serotonin-related mRNA expression in colon tissue. Therefore, we deduced that the mixed Lactobacillus strains could alleviate intestinal inflammation by recovering the intestinal flora dysbiosis, increasing serotonin expression, and activating the 5-HT7R and 5-HT4R, which would provide a new idea to assess the ameliorating effect of probiotic strains on inflammatory bowel disease.

TRPC absence induces pro-inflammatory macrophages and gut microbe disorder, sensitizing mice to colitis.

The transient receptor potential canonical (TRPC) channels, encoded in seven non-allelic genes, are important contributors to calcium fluxes, are strongly associated with various diseases. Here we explored the consequences of ablating all seven TRPCs in mice focusing on colitis. We discovered that absence of all seven TRPC proteins in mice (TRPC HeptaKO mice) promotes the development of dextran sulfate sodium (DSS)-induced colitis. RNA-sequence analysis highlighted an extremely pro-inflammatory profile in colons of DSS-treated TRPC HeptaKO mice, with an amount of increased pro-inflammatory cytokines and chemokines. Flow cytometry analysis showed that the infiltration of Ly6Chi monocytes and neutrophils in colonic lamina propria was significantly increased in DSS-treated TRPC HeptaKO mice. Results also revealed that macrophages from TRPC HeptaKO mice exhibited M1 polarization and enhanced secretion of pro-inflammatory factors. In addition, the composition of gut microbiota was markedly disturbed in DSS-treated TRPC HeptaKO mice. However, upon antibiotic cocktail (Abx)-treatment, TRPC HeptaKO mice showed no significant differences with WT mice in disease severity. Collectively, these data suggest that ablation of all TRPCs promotes the development of DSS-induced colitis by inducing pro-inflammatory macrophages and gut microbiota disorder.

Gut microbiota-derived ursodeoxycholic acid alleviates low birth weight-induced colonic inflammation by enhancing M2 macrophage polarization

BackgroundLow birth weight (LBW) is associated with intestinal inflammation and dysbiosis after birth. However, the underlying mechanism remains largely unknown.ObjectiveIn the present study, we aimed to investigate the metabolism, therapeutic potential, and mechanisms of action of bile acids (BAs) in LBW-induced intestinal inflammation in a piglet model.MethodsThe fecal microbiome and BA profile between LBW and normal birth weight (NBW) neonatal piglets were compared. Fecal microbiota transplantation (FMT) was employed to further confirm the linkage between microbial BA metabolism and intestinal inflammation. The therapeutic potential of ursodeoxycholic acid (UDCA), a highly differentially abundant BA between LBW and NBW piglets, in alleviating colonic inflammation was evaluated in both LBW piglets, an LBW-FMT mice model, and a DSS-induced colitis mouse model. The underlying cellular and molecular mechanisms by which UDCA suppresses intestinal inflammation were also investigated in both DSS-treated mice and a macrophage cell line. Microbiomes were analyzed by using 16S ribosomal RNA sequencing. Fecal and intestinal BA profiles were measured by using targeted BA metabolomics. Levels of farnesoid X receptor (FXR) were knocked down in J774A.1 cells with small interfering RNAs.ResultsWe show a significant difference in both the fecal microbiome and BA profiles between LBW and normal birth weight animals in a piglet model. Transplantation of the microbiota of LBW piglets to antibiotic-treated mice leads to intestinal inflammation. Importantly, oral administration of UDCA, a major BA diminished in the intestinal tract of LBW piglets, markedly alleviates intestinal inflammation in LBW piglets, an LBW-FMT mice model, and a mouse model of colitis by inducing M2 macrophage polarization. Mechanistically, UDCA reduces inflammatory cytokine production by engaging BA receptor FXR while suppressing NF-κB activation in macrophages.ConclusionsThese findings establish a causal relationship between LBW-associated intestinal abnormalities and dysbiosis, suggesting that restoring intestinal health and postnatal maldevelopment of LBW infants may be achieved by targeting intestinal microbiota and BA metabolism.Csb1K8fsfkBeFAHhY-1wroVideo

P012 The administration of mm-miR-378a-3p exacerbates chronic inflammation and fibrosis in a murine intestinal model

Abstract Background Fibrosis constitute an important complication of CD. MicroRNAs (miRNAs), which are small RNA molecules that regulate gene expression, have been shown to participate in the molecular interactions of both inflammation and fibrosis. Lower levels of miR-378a-3p have been reported associated to murine liver fibrosis (Hyun et al. DOI: 10.1038/ncomms10993) and we analyze here the relevance of miR-378a-3p on intestinal fibrosis. Methods B57BL/6 mice were intravenously injected with 2,5mg/kg of negative control (NC) or mm-miR-378a-3p mimic, twice a week and received vehicle or Dextran Sulfate Sodium (DSS) for 2 cycles (7 days drinking DSS 2% in water solution followed by 10 days drinking water). Body weight and DAI score was obtained every day and the colon was collected after sacrifice. Sirius and hematoxylin-eosin dyes were employed to determine the fibrosis and structural state in 5µm slides of intestinal tissue. Gene expression and miRNA profiles were analyzed by RT-qPCR. Human small intestinal fibroblasts (HSIF; P10760, Innoprot, Spain) were transfected with 20nM of NC or hsa-miR-378a-3p mimic during 24h. Results No significant changes in body weight, DAI score, and colon length were detected between mice receiving NC and those receiving mimic, all along the two DSS cycles. Colon of mice treated with DSS, exhibited a significant diminution in the mRNA expression of mm-miR-378a-3p compared with naïve samples. In DSS-treated mice, the iv administration of the mimic compared with the NC: a) significantly increased levels of miR-378a-3p in the colon; b) increased the number of neutrophils, and heightened changes in the glandular epithelia and architectural distortion (figure 1a) C) decreased the number of lymphoid follicles (figure 1a); d) slightly increased collagen deposition, as analyzed by sirius red (figure 1b) and e) significantly increased the mRNA expression of Tgfb1, Il1b, and Mmp2. Treatment of human intestinal fibroblasts with hsa-miR-378a-3p mimic did not significant modify the mRNA expression of markers of fibrosis but it significantly increased the mRNA expression of two antiapoptotic molecules BCL2 and MCL1. Conclusion Levels of mm-miR-378a-3p are diminished in a murine model of intestinal fibrosis; The exogenous administration of miR-378a-3p, increased the acute inflammatory response and the expression of fibrosis markers in murine fibrotic colon and the expression of antiapoptotic molecules in human intestinal fibroblasts.

Protective role of colitis in inflammatory arthritis via propionate-producing Bacteroides in the gut.

To investigate whether and how inflammatory disease in the intestine influences the development of arthritis, considering that organ-to-organ communication is associated with many physiological and pathological events. First, mice were given drinking water containing dextran sodium sulfate (DSS) and then subjected to inflammatory arthritis. We compared the phenotypic symptoms between the cohoused and separately-housed mice. Next, donor mice were divided into DSS-treated and untreated groups and then cohoused with recipient mice. Arthritis was then induced in the recipients. The fecal microbiome was analyzed by 16S rRNA amplicon sequencing. We obtained type strains of the candidate bacteria and generated propionate-deficient mutant bacteria. Short-chain fatty acids were measured in the bacterial culture supernatant, serum, feces, and cecum contents using gas chromatography-mass spectrometry. Mice fed with candidate and mutant bacteria were subjected to inflammatory arthritis. Contrary to expectations, the mice treated with DSS exhibited fewer symptoms of inflammatory arthritis. Intriguingly, the gut microbiota contributes, at least in part, to the improvement of colitis-mediated arthritis. Among the altered microorganisms, Bacteroides vulgatus and its higher taxonomic ranks were enriched in the DSS-treated mice. B. vulgatus, B. caccae, and B. thetaiotaomicron exerted anti-arthritic effects. Propionate production deficiency further prevented the protective effect of B. thetaiotaomicron on arthritis. We suggest a novel relationship between the gut and joints and an important role of the gut microbiota as communicators. Moreover, the propionate-producing Bacteroides species examined in this study may be a potential candidate for developing effective treatments for inflammatory arthritis.

P913 Interactions between Intestinal Microbiota and micro-RNAs in Inflammatory Bowel Disease

Abstract Background Both gut microbiota and micro-RNAs (miRNAs) have been implicated in the pathogenesis of inflammatory bowel disease (IBD). We aimed to investigate the interactions between gut microbiota and miRNAs which are altered in murine colitis models and patients with IBD using multi-omics analysis. Methods Gut microbiota and miRNAs were analyzed in a mouse experiment (7 dextran sodium sulfate [DSS]-treated mice, 7 azoxymethane [AOM] and DSS-treated mice, and 6 controls) and a human experiment (10 patients with active Crohn’s disease, 10 patients with active ulcerative colitis [UC], and 8 healthy controls). DNA was extracted from mouse feces and human colonic tissues, and 16S rRNA gene sequencing was performed to evaluate changes in gut microbiota. miRNA expression levels were measured by microarray analysis from mouse and human colonic tissues. mRNA expression levels were examined by microarray analysis from colonic tissues of UC patients. Correlation and network analyses were performed to evaluate the interactions among gut microbiota, miRNAs and mRNAs. Results Principal coordinate analysis showed distinct gut microbiota composition and miRNA expressions among the groups in the mouse and human experiments. Also, comparative analysis showed many miRNAs differentially expressed and many bacterial amplicon sequence variants (ASVs) differentially identified among the groups. Spearman correlation rank test and network analysis revealed multiple correlations and interactions among specific miRNAs and bacterial ASVs. In UC patients, genes associated with functional categories in biological process, such as positive regulation of cytokine production, cytokine-mediated signaling pathway, cell adhesion, positive regulation of response to external stimulus, and leukocyte migration were upregulated than healthy controls. mRNAs in UC patients also showed multiple correlations and interactions with specific miRNAs and bacterial ASVs. Conclusion Gut microbiota composition and miRNA expressions were distinctly altered in patients with IBD and murine colitis models. Specific miRNAs were associated with specific bacterial ASVs and mRNAs, suggesting the interactions among miRNAs, gut microbiota and mRNAs in the pathogenesis of IBD. Our data imply that global complicated interactions between gut microbiota and miRNAs, rather than specific individual microbiota-miRNA interaction, might play more important role in IBD.

ESTABLISHMENT AND TREATMENT OF MURINE COLONOIDS TO STUDY THE EPITHELIAL EFFECTS OF INTESTINAL INFLAMMATION IN VITRO

Abstract BACKGROUND Disruption of the intestinal epithelial barrier is a hallmark of inflammatory bowel disease (IBD). The 3-dimensional colonoid culture system is a useful in vitro model to study intestinal stem cell dynamics and epithelial cell physiology in IBD pathogenesis. However, we have shown that in vivo epithelial changes are not necessarily retained in colonoids established from mice undergoing acute inflammation using a DSS model and primarily reflect stem cell physiology rather than that of terminally differentiated cells. We developed experimental methods to address this limitation. We terminally differentiate colonoids or create 2-D monolayers, and challenge them with a cocktail of inflammatory mediators that are typically elevated during IBD. METHODS Murine colonoids are established by isolating colonic crypts and plating them in basement membrane matrix. Over 3 to 5 days, crypt structures develop into spheroid colonoids 250 μm in diameter, forming a prominent lumen surrounded by a thin layer of epithelial stem cells. They are passaged a minimum of two times and then are either 1) terminally differentiated by incubating the colonoids with Differentiating Media or 2) used to establish intestinal epithelial monolayers. Inflammation is then induced by incubating cells with a cocktail of inflammatory mediators (TNFa, IL-1b, IFNg, H2O2). Protein is collected after 72 hours, and expression of proteins involved in mitochondrial biogenesis were assessed (n=3). RESULTS We found that changes in mitochondrial dynamics, reflective of key metabolic changes in the epithelium that are observed in colonic scrapings of DSS-treated mice are not recapitulated in traditional colonoids derived from mice on the same DSS regimen. We found that changes in expression and protein levels of peroxisome proliferator-activator receptor-gamma coactivator-1a (PGC1a), the master regulator protein of mitochondrial biogenesis, were not maintained in colonoids. After terminally differentiating colonoids and subsequently inducing inflammation, we were able to recapitulate a failure of mitochondrial biogenesis failure that is a hallmark of both human IBD and murine colitis. Protein expression of PGC1a as well as downstream transcription factor A, mitochondria (TFAM) were both decreased when assessed via western blot. DISCUSSION Colonoids are a useful tool for studying colonic physiology in vitro, however are limited in their ability to evaluate the effects of in vivo inflammation on the mitochondrial function and cellular metabolism. When removed from the intestinal milieu, crypt cells demonstrate a recovery of mitochondrial health and reflect stem primarily stem cell physiology. Our strategies provide opportunities for organoid manipulation which, when employed properly, can shed light on key aspects of intestinal epithelial mitochondrial function during inflammation.

MANF ameliorates DSS-induced mouse colitis via restricting Ly6ChiCX3CR1int macrophage transformation and suppressing CHOP-BATF2 signaling pathway

Mesencephalic astrocyte-derived neurotrophic factor (MANF), an endoplasmic reticulum stress-inducible secreting protein, has evolutionarily conserved immune-regulatory function that contributes to the negative regulation of inflammation in macrophages. In this study, we investigated the profiles of MANF in the macrophages of the patients with active inflammatory bowel disease (IBD) and the mice with experimental colitis, which was induced in both myeloid cell-specific MANF knockout mice and wild-type mice by 3% dextran sodium sulfate (DSS) for 7 days. We found that MANF expression was significantly increased in intestinal macrophages from both the mice with experimental colitis and patients with active IBD. DSS-induced colitis was exacerbated in myeloid cell-specific MANF knockout mice. Injection of recombinant human MANF (rhMANF, 10 mg·kg–1·d–1, i.v.) from D4 to D6 significantly ameliorated experimental colitis in DSS-treated mice. More importantly, MANF deficiency in myeloid cells resulted in a dramatic increase in the number of Ly6ChiCX3CRint proinflammatory macrophages in colon lamina propria of DSS-treated mice, and the proinflammatory cytokines and chemokines were upregulated as well. Meanwhile, we demonstrated that MANF attenuated Th17-mediated immunopathology by inhibiting BATF2-mediated innate immune response and downregulating CXCL9, CXCL10, CXCL11 and IL-12p40; MANF functioned as a negative regulator in inflammatory macrophages via inhibiting CHOP-BATF2 signaling pathway, thereby protecting against DSS-induced mouse colitis. These results suggest that MANF ameliorates colon injury by negatively regulating inflammatory macrophage transformation, which shed light on a potential therapeutic target for IBD.

MSI2 deficiency in ILC3s attenuates DSS-induced colitis by affecting the intestinal microbiota.

The etiology and pathogenesis of inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), are generally believed to be related to immune dysfunction and intestinal microbiota disorder. However, the exact mechanism is not yet fully understood. The pathological changes associated with dextran sodium sulfate (DSS)-induced colitis are similar to those in human UC. As a subgroup of the innate immune system, group 3 innate lymphoid cells (ILC3s) are widely distributed in the lamina propria of the intestinal mucosa, and their function can be regulated by a variety of molecules. Musashi2 (MSI2) is a type of evolutionarily conserved RNA-binding protein that maintains the function of various tissue stem cells and is essential for postintestinal epithelial regeneration. The effect of MSI2 deficiency in ILC3s on IBD has not been reported. Thus, mice with conditional MSI2 knockout in ILC3s were used to construct a DSS-induced colitis model and explore its effects on the pathogenesis of IBD and the species, quantity and function of the intestinal microbiota. Msi2flox/flox mice (Msi2fl/fl ) and Msi2flox/floxRorcCre mice (Msi2ΔRorc ) were induced by DSS to establish the IBD model. The severity of colitis was evaluated by five measurements: body weight percentage, disease activity index, colon shortening degree, histopathological score and routine blood examination. The species, quantity and function of the intestinal microbiota were characterized by high-throughput 16S rRNA gene sequencing of DNA extracted from fecal samples. MSI2 was knocked out in the ILC3s of Msi2ΔRorc mice. The Msi2ΔRorc mice exhibited reductions in body weight loss, the disease activity index, degree of colon shortening, tissue histopathological score and immune cells in the peripheral blood compared to those of Msi2fl/fl mice after DSS administration. The 16S rRNA sequencing results showed that the diversity of the intestinal microbiota in DSS-treated Msi2ΔRorc mice changed, with the abundance of Firmicutes increasing and that of Bacteroidetes decreasing. The linear discriminant analysis effect size (LEfSe) approach revealed that Lactobacillaceae could be the key bacteria in the Msi2ΔRorc mouse during the improvement of colitis. Using PICRUST2 to predict the function of the intestinal microbiota, it was found that the functions of differential bacteria inferred by modeling were mainly enriched in infectious diseases, immune system and metabolic functions. MSI2 deficiency in ILC3s attenuated DSS-induced colonic inflammation in mice and affected intestinal microbiota diversity, composition, and function, with Lactobacillaceae belonging to the phylum Firmicutes possibly representing the key bacteria. This finding could contribute to our understanding of the pathogenesis of IBD and provide new insights for its clinical diagnosis and treatment.

Dietary 5-demethylnobiletin attenuated dextran sulfate sodium-induced colitis in mice by inhibiting immune response and regulating gut microbiota.

This study investigated the preventive effect of 5-demethylnobiletin (5DN), a natural polymethoxyflavone found mainly in citrus fruits, on dextran sulfate sodium (DSS)-induced colitis in mice and explored its potential mechanisms. Our results indicated that dietary 5DN (0.05% w/w in diet) could alleviate colitis symptoms in DSS-treated mice by preventing body weight loss, reducing the disease activity index, decreasing the colon weight to colon length ratio, and lessening colon tissue damage. Additionally, 5DN inhibited the inflammatory response in colitis mice through decreasing the production of inflammatory cytokines. Immunohistochemical analysis revealed that 5DN could reverse the DSS-induced decrease in the expression of claudin-1 and ZO-1 to improve the intestinal barrier function. Furthermore, 5DN altered gut microbiota dysbiosis in DSS-treated mice via up-regulating the level of probiotics (Roseburia) and down-regulating the level of pathogenic bacteria (Clostridium, Parabacteroides, and Sutterella). Taken together, these data provided a solid scientific basis for utilizing 5DN as a therapeutic candidate in colitis and related diseases.

Salidroside alleviates dextran sulfate sodium-induced colitis in mice by modulating the gut microbiota.

Dysbiosis causes continuous progress of inflammatory bowel disease (IBD). Herein, we aim to explore whether Salidroside (Sal), which is a major glycoside extracted from Rhodiola rosea L., could ameliorate dextran sulfate sodium (DSS)-induced colitis by modulating the microbiota. Results showed that oral treatment with 15 mg kg-1 of Sal inhibited DSS-induced colitis in mice as evidenced by colon length, histological analysis, disease activity index (DAI) score, and the proportion and number of macrophages in the intestine. The gut microbiota of colitic mice was also partly restored by Sal. A fecal microbiota transplantation (FMT) study was designed to verify the causality. Compared with DSS-treated mice, FM from the Sal-treated donor mice significantly mitigated the symptoms of colitic mice, including reducing the DAI score, alleviating tissue damage, boosting the expression of mucin protein (mucin-2) and tight junction (TJ) proteins (occludin and zonula occludens-1 (ZO-1), and decreasing M1 macrophages in the gut. It was found that both Sal and FMT affected the structure and abundance of the gut microbiota as reflected by the decreased relative abundance of Turicibacter, Alistipes, Romboutsia and the increased relative abundance of Lactobacillus at the genus level. Moreover, the anti-inflammatory effect of Sal disappeared when the gut microbiota was depleted by antibiotics, demonstrating that Sal alleviated the intestinal inflammation in a gut microbiota-dependent manner. Thus, Sal could be a remarkable candidate as a functional food for colitis.

Extract of Laurus nobilis attenuates inflammation and epithelial ulcerations in an experimental model of inflammatory bowel disease

Inflammatory bowel diseases (IBD), including Crohn's disease and ulcerative colitis, are classified as chronic inflammatory disorders and typically require anti-inflammatory drug therapies, such as glucocorticoid regimens, non-steroidal anti-inflammatory drugs, and biologics, aimed at reducing inflammation in the bowel wall. However, each of these therapies is accompanied by a list of possible serious side effects. Because of this, there remains an urgent need to identify new pharmacologic options to reduce or prevent the pro-inflammatory events of IBD while minimizing adverse side effects and making available more cost-effective treatment modalities. We have previously identified several herbal extracts that demonstrate the potent bio-inhibitory activity of the innate immune response. In particular, Laurus nobilis (LN), or more commonly called bay laurel, demonstrated significant anti-inflammatory function by inhibiting nuclear factor-κB activation. Based upon our original in vitro findings, we have now examined the effects of this herbal extract on a murine dextran sodium sulfate (DSS) model of IBD. Hematoxylin and eosin-stained paraffin sections prepared from DSS-treated animals show clear epithelial damage, including ulcerations, extensive neutrophil infiltration into the mucosal layer, and granuloma formation. Tissue from DSS-treated animals that also received LN extract showed improved tissue morphology more closely resembling that from control animals. In addition, DSS-treated mice with co-administration of LN extract showed a significant reduction in CD4+ antibody staining within the mucosal layer in colonic sections indicating reduced lymphocyte infiltration. Based on these findings, we believe that the administration of LN extracts may be effective in reducing the intestinal epithelial damage seen in human IBD and warrants further investigation through clinical trials. Lay Summary: Inflammatory bowel diseases (IBD), such as Crohn's disease (CD) and ulcerative colitis (UC), manifest as chronic inflammation and ulceration of tissues lining the digestive tract. CD involves inflammation of the deeper layers of the digestive tract, including both the small and large intestines, and less commonly, the upper digestive tract. UC involves inflammation along the lining of the colon and rectum. Steroid or biological treatments for IBD are common, however, they are limited due to significant side effects and/or prohibitive costs. In the present study, we provide evidence for use of the natural product, Laurus nobilis (bay leaf), as a safe and effective anti-inflammatory therapy for IBD.

Involvement of Brn3a-positive spinal dorsal horn neurons in the transmission of visceral pain in inflammatory bowel disease model mice.

The spinal dorsal horn plays a crucial role in the transmission and processing of somatosensory information. Although spinal neural circuits that process several distinct types of somatic sensations have been studied extensively, those responsible for visceral pain transmission remain poorly understood. In the present study, we analyzed dextran sodium sulfate (DSS)-induced inflammatory bowel disease (IBD) mouse models to characterize the spinal dorsal horn neurons involved in visceral pain transmission. Immunostaining for c-fos, a marker of neuronal activity, demonstrated that numerous c-fos-positive cells were found bilaterally in the lumbosacral spinal dorsal horn, and their distribution was particularly abundant in the shallow dorsal horn. Characterization of these neurons by several molecular markers revealed that the percentage of the Pit1-Oct1-Unc86 domain (POU domain)-containing transcription factor Brn3a-positive neurons among the c-fos-positive neurons in the shallow dorsal horn was 30%-40% in DSS-treated mice, which was significantly higher than that in the somatic pain model mice. We further demonstrated by neuronal tracing that, within the shallow dorsal horn, Brn3a-positive neurons were more highly represented in spino-solitary projection neurons than in spino-parabrachial projection neurons. These results raise the possibility that Brn3a-positive spinal dorsal horn neurons make a large contribution to visceral pain transmission, part of which is mediated through the spino-solitary pathway.

Opposing Roles of DCs and iNKT Cells in the Induction of Foxp3 Expression by MLN CD25+CD4+ T Cells during IFNγ-Driven Colitis

We have previously shown that a deficiency of CD1d-restricted invariant natural killer T (iNKT) cells exacerbates dextran sulfate sodium (DSS)-induced colitis in Yeti mice that exhibit IFNγ-mediated hyper-inflammation. Although iNKT cell-deficiency resulted in reduced Foxp3 expression by mesenteric lymph node (MLN) CD4+ T cells in DSS-treated Yeti mice, the cellular mechanisms that regulate Foxp3 expression by CD25+CD4+ T cells during intestinal inflammation remain unclear. We found that Foxp3-CD25+CD4+ T cells expressing Th1 and Th17 phenotypic hallmarks preferentially expanded in the MLNs of DSS-treated Yeti/CD1d knockout (KO) mice. Moreover, adoptive transfer of Yeti iNKT cells into iNKT cell-deficient Jα18 KO mice effectively suppressed the expansion of MLN Foxp3-CD25+CD4+ T cells during DSS-induced colitis. Interestingly, MLN dendritic cells (DCs) purified from DSS-treated Yeti/CD1d KO mice promoted the differentiation of naive CD4+ T cells into Foxp3-CD25+CD4+ T cells rather than regulatory T (Treg) cells, indicating that MLN DCs might mediate Foxp3+CD25+CD4+ T cell expansion in iNKT cell-sufficient Yeti mice. Furthermore, we showed that Foxp3-CD25+CD4+ T cells were pathogenic in DSS-treated Yeti/CD1d KO mice. Our result suggests that pro-inflammatory DCs and CD1d-restricted iNKT cells play opposing roles in Foxp3 expression by MLN CD25+CD4+ T cells during IFNγ-mediated intestinal inflammation, with potential therapeutic implications.

Broccoli-Derived Glucoraphanin Activates AMPK/PGC1α/NRF2 Pathway and Ameliorates Dextran-Sulphate-Sodium-Induced Colitis in Mice.

As the prevalence of inflammatory bowel diseases (IBD) rises, the etiology of IBD draws increasing attention. Glucoraphanin (GRP), enriched in cruciferous vegetables, is a precursor of sulforaphane, known to have anti-inflammatory and antioxidative effects. We hypothesized that dietary GRP supplementation can prevent mitochondrial dysfunction and oxidative stress in an acute colitis mouse model induced by dextran sulfate sodium (DSS). Eight-week-old mice were fed a regular rodent diet either supplemented with or without GRP. After 4 weeks of dietary treatments, half of the mice within each dietary group were subjected to 2.5% DSS treatment to induce colitis. Dietary GRP decreased DSS-induced body weight loss, disease activity index, and colon shortening. Glucoraphanin supplementation protected the colonic histological structure, suppressed inflammatory cytokines, interleukin (IL)-1β, IL-18, and tumor necrosis factor-α (TNF-α), and reduced macrophage infiltration in colonic tissues. Consistently, dietary GRP activated AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1α, and nuclear factor erythroid 2-related factor 2 (NRF2) pathways in the colonic tissues of DSS-treated mice, which was associated with increased mitochondrial DNA and decreased content of the oxidative product 8-hydroxydeoxyguanosine (8-OHDG), a nucleotide oxidative product of DNA. In conclusion, dietary GRP attenuated mitochondrial dysfunction, inflammatory response, and oxidative stress induced by DSS, suggesting that dietary GRP provides a dietary strategy to alleviate IBD symptoms.

TDAG51 deficiency attenuates dextran sulfate sodium-induced colitis in mice

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn’s disease, is a group of chronic inflammatory diseases of the gastrointestinal tract. Although the multifactorial etiology of IBD pathogenesis is relatively well documented, the regulatory factors that confer a risk of IBD pathogenesis remain less explored. In this study, we report that T-cell death-associated gene 51 (TDAG51/PHLDA1) is a novel regulator of the development of dextran sulfate sodium (DSS)-induced colitis in mice. TDAG51 expression was elevated in the colon tissues of DSS-induced experimental colitis mice. TDAG51 deficiency protected mice against acute DSS-induced lethality and body weight changes and disease severity. DSS-induced structural damage and mucus secretion in colon tissues were significantly reduced in TDAG51-deficient mice compared with wild-type mice. We observed similar results in a DSS-induced chronic colitis mouse model. Finally, we showed that the production of inflammatory mediators, including proinflammatory enzymes, molecules and cytokines, was decreased in DSS-treated TDAG51-deficient mice compared with DSS-treated wild-type mice. Thus, we demonstrated that TDAG51 deficiency plays a protective role against DSS-induced colitis by decreasing the production of inflammatory mediators in mice. These findings suggest that TDAG51 is a novel regulator of the development of DSS-induced colitis and is a potential therapeutic target for IBD.