Dextran Sulfate Sodium Treatment Research Articles

A59 EXPLORING THE ROLE OF ARID1A IN COLONIC HOMEOSTASIS AND REGENERATION

Abstract Background Recent advances in cancer genome analysis have revealed frequently mutated epigenetic regulators as a novel feature in cancer development. Within this context, the Arid1a (AT-rich interactive domain-containing protein 1A) gene, a subunit of the BAF chromatin remodeling complex, has emerged as a frequently mutated gene in many cancers. Additionally, repeated colonic injury caused by diseases such as inflammatory bowel disease (IBD), is also a major risk factor leading to colorectal cancer. Therefore, understanding the connection between colonic epigenetic regulation and its role in response to injury is particularly important for understanding the pathobiology of colorectal cancer. Aims Aim 1: Exploring the role of Arid1a during colonic homeostasis. Mouse model with Arid1a conditionally knocked out in the colon will be analysed at different time points to test whether Arid1a is required during colonic homeostasis. Aim 2: Determining the role of Arid1a during colonic injury and regeneration. Mice will be exposed to a known colitis model to induce colonic injury. Arid1a will be deleted after injury to find out its role during regeneration and recovery from the injury. Methods To examine the effect of Arid1a loss on colonic homeostasis, mice between 6-10 weeks old were injected with 2mg/20g tamoxifen for three days to induce Arid1a knockout using the VilCreERT2; Arid1afl/fl mousseline. Mice were then euthanised using CO2 chamber and analysed 10 days, 3 weeks, and 8 weeks post Arid1a deletion. Histological analysis was performed to examine morphological changes in the colon. To examine the effect of Arid1a on injury caused by colitis, mice were treated with dextran sulfate sodium (DSS) to cause colitis-like injury. Then, Arid1a is deleted by injecting 2mg/20g tamoxifen. Changes in histology and specific cell types will be examined both in the short- and long-term. Results To test whether Arid1a loss alone causes morphological changes in the colon, I compared the crypt lengths between VilCreERT2; Arid1afl/fl mutant mice with their littermate controls and saw that there was no difference in both morphology and length of the crypts. My results show that Arid1a loss in the colon after injury resulted in impaired regeneration characterized by the prolonged loss of goblet cells and cryptal structure in the distal colon. In the long term, Arid1a loss before or after DSS treatment both lead to tumor formation, suggesting that Arid1a is required for colonic regeneration and repair while suppressing tumorigenesis. Conclusions Based on my results, I conclude that Arid1a deletion alone does not cause significant morphological changes in the colon, but this loss affects colonic regeneration and recovery compared to colons with Arid1a intact. In the long term, the dysregulated colonic regeneration may lead to tumorigenesis. Funding Agencies University of Toronto Department of Molecular Genetics

Regulation of Gut Microbiota and Microbial Metabolome of Kefir Supernatant against Fusobacterium nucleatum and DSS-Coinduced Colitis.

The aim of this study was to investigate the intervention effect of kefir supernatant (KS) on the initiation and progression of an ulcerative colitis (UC) murine model. We established an UC murine model by orally administrating with 109 CFUs of Fusobacterium nucleatum for 3 weeks and 3% dextran sulfate sodium (DSS) treatment in the third week. KS was used to intervene in this colitis model. Our results showed that KS supplementation ameliorated the symptoms, restrained the secretion of pro-inflammatory cytokines (TNF-α, IL-6, and IL-17F), promoted the release of anti-inflammatory cytokines (IL-4 and IL-10), and ameliorated oxidative stress. Furthermore, the increased number of goblet cells and upregulated expression of MUC2, occludin and claudin-1 indicated that the colon barrier was protected by KS. Additionally, KS supplementation mitigated gut microbiota dysbiosis in the UC murine model, leading to an increase in the abundance of Blautia and Akkermansia and a decrease in the level of Bacteroides. The altered gut microbiota also affected colon metabolism, with differential metabolites mainly associated with the biosynthesis of the l-arginine pathway. This study revealed that KS supplementation restored the community structure of gut microbiota, altered the biosynthesis of l-arginine, and thereby modulated the process of colonic inflammation.

Living, Heat-Killed Limosilactobacillus mucosae and Its Cell-Free Supernatant Differentially Regulate Colonic Serotonin Receptors and Immune Response in Experimental Colitis.

Lactobacillus species have been shown to alleviate gut inflammation and oxidative stress. However, the effect of different lactobacilli components on gut inflammation has not been well studied. This study aims to identify the differences in the effect and mechanisms of different forms and components of Limosilactobacillus mucosae (LM) treatment in the alleviation of gut inflammation using a colitis mouse model that is induced by dextran sodium sulfate (DSS). Seventy-two C57BL/6 mice were divided into six groups: control, DSS, live LM+DSS (LM+DSS), heat-killed LM+DSS (HKLM+DSS), LM cell-free supernatant + DSS (LMCS+DSS), and MRS medium + DSS (MRS+DSS). The mice were treated with different forms and components of LM for two weeks before DSS treatment. After that, the mice were sacrificed for an assessment of their levels of inflammatory cytokines, serotonin (5-HT) receptors (HTRs), and tryptophan metabolites. The results showed that, compared to other treatments, LMCS was more effective (p < 0.05) in the alleviation of DSS-induced body weight loss and led to an increase in the disease activity index score. All three forms and components of LM increased (p < 0.05) the levels of indole-3-acetic acid but reduced (p < 0.05) the levels of 5-HT in the colon. HKLM or LMCS reduced (p < 0.05) the percentages of CD3+CD8+ cytotoxic T cells but increased (p < 0.05) the percentages of CD3+CD4+ T helper cells in the spleen. LM or HKLM increased (p < 0.05) abundances of CD4+Foxp3+ regulatory T cells in the spleen. The LM and LMCS treatments reduced (p < 0.05) the expression of the pro-inflammatory cytokines Il6 and Il17a. The mice in the HKLM+DSS group had higher (p < 0.05) mRNA levels of the anti-inflammatory cytokine Il10, the cell differentiation and proliferation markers Lgr5 and Ki67, the 5-HT degradation enzyme Maoa, and HTRs (Htr1a, Htr2a, and Htr2b) in the colon. All three forms and components of LM reduced the phosphorylation of STAT3. The above findings can help to optimize the functionality of probiotics and develop new dietary strategies that aid in the maintenance of a healthy gut.

Alterations in metabolome and microbiome: new clues on cathelicidin-related antimicrobial peptide alleviates acute ulcerative colitis.

Ulcerative colitis (UC) is a chronic and recurrent inflammatory disease of the gastrointestinal tract. This study aimed to determine the effect of cathelicidin-related antimicrobial peptide (Cramp) on dextran sulfate sodium (DSS)-induced acute experimental colitis in mice and to investigate the underlying mechanisms. Acute UC was induced in C57BL/6 mice with 3% DSS for 7 days, 4 mg/kg b.w. synthetic Cramp peptide was administrated once daily starting on day 4 of the experimental period. Mice were evaluated for body weight, colon length, colon histopathology, and inflammatory cytokines in colon tissue. Using 16 s rRNA sequencing, the composition structure of gut microbiota was characterized. Metabolomic profiling of the serum was performed. The results showed that DSS treatment significantly induced intestinal damage as reflected by disease activity index, histopathological features, and colon length, while Cramp treatment significantly prevented these trends. Meanwhile, Cramp treatment decreased the levels of inflammatory cytokines in both serum and colonic tissue on DSS-induced colitis. It was also observed that DSS damaged the integrity of the intestinal epithelial barrier, whereas Cramp also played a protective role by attenuating these deteriorated effects. Furthermore, Cramp treatment reversed the oxidative stress by increasing the antioxidant enzymes of GSH-PX and decreasing the oxidant content of MDA. Notably, compared to the DSS group, Cramp treatment significantly elevated the abundance of Verrucomicrobiota at the phylum level. Furthermore, at the genus level, Parasutterella and Mucispirllum abundance was increased significantly in response to Cramp treatment, although Roseburia and Enterorhabdus reduced remarkably. Metabolic pathway analysis of serum metabolomics showed that Cramp intervention can regulate various metabolic pathways such as α-linolenic acid, taurine and hypotaurine, sphingolipid, and arachidonic acid metabolism. The study concluded that Cramp significantly ameliorated DSS-induced colonic injury, colonic inflammation, and intestinal barrier dysfunction in mice. The underlying mechanism is closely related to the metabolic alterations derived from gut microbiota.

P031 Microbiota-driven appendiceal B lymphocytes aggravate DSS-induced murine colitis through facilitating colonic CD4+ T cells polarization

Abstract Background The appendix is an immunological organ sustaining a microbiome inoculum that plays a vital role in intestinal mucosal immunity and colonic microbiome stability. Previous studies have proposed the appendix exerts effects on ulcerative colitis (UC)’s pathogenesis, but the nature and basis underlying this connection remain unclear. B lymphocytes account for the largest proportion of appendiceal immunocytes and activate in the experimental colitis model, we systematically investigated how appendiceal B lymphocytes (appB) participate in UC’s pathogenesis and provided rational evidence for appendectomy and B cell immunotherapy being used in UC treatments. Methods The chronic colitis model was established in C57BL/6J mice by three cycles of 2% dextran sodium sulfate (DSS) treatment. Bulk RNA sequencing and 16S rRNA sequencing were used to explore appB’s characteristics and the potential causes of appB activation in DSS-induced colitis. Adoptive appB transfer and intravital imaging were used to evaluate appB’s homing and functional features in DSS-induced chronic colitis. Magnetic microbead-based cell sorting and cells experiments in vitro were used to investigate the underlying mechanisms of appB’s activation and effects on DSS-induced chronic colitis. Flow cytometry was used to assess the colonic mucosal adaptive immunity alterations in colitis mice adopted appB. Results Firmicutes and Bacteroidetes are the dominant phylum in the normal appendix, while Firmicutes, Verrucomicrobia, and Proteobacteria are prominent in the colitis appendix. The appendiceal IgG+ B cells expended in colitis mice compared with the normal mice; and the DSS colitis appB (DSS_appB), compared with the normal control appB (NC_appB), had much more potential to migrate to the colon and fired the gut flare, accompanied by the increment of CD19+ IgG+ cells, CD4+ IFN-γ+ cells and CD4+ IL-17+ cells in the colonic lamina propria in colitis mice. In vitro, DSS_appB secreted more inflammatory cytokines (IFN-γ, IL-6) than NC_appB under the stimulation of Toll-like receptor agonist analogs (Pam3CSK4, LPS, and ODN1826); DSS_appB facilitated colonic CD4+ T cells to secrete IFN-γ and IL-17 by up-regulating surface marker (CD80/86) and secreting IFN-γ and IL-6. Conclusion In DSS-induced chronic colitis mice, appB activated, driven by appendiceal microbiota,migrated to the colonic lamina propria and aggravated colitis through facilitating CD4+ Tcells polarize to Th1 and Th17 by up-regulating CD80/86 and secreting IFN-γ and IL-6 (Figure 1). Our research provides evidence for the connection between the appendix and UC, and we propose that appendectomy or B cell immunotherapy is promising to treat UC.

Effects of Sichuan pepper (huājiāo) powder on disease activity and caecal microbiota of dextran sodium sulphate-induced inflammatory bowel disease mouse model.

Sichuan pepper [Zanthoxylum bungeanum; huājiāo (HJ)] is a widely used spice in China and has better antioxidative, anti-glycation, and bile acid-lowering properties than cumin and coriander seeds. HJ affects inflammation-related cytokines and caecal microbiota in mice fed a low-fibre and high-sucrose diet. To determine the ameliorative effect of HJ on inflammatory bowel disease, C57BL/6 mice were divided into three groups and fed distilled water (control) or 3% (w/v) dextran sodium sulphate (DSS) in drinking water with normal chow containing 0% or 5% (w/w) HJ powder for seven days. After 6 days of feeding, diarrhoea, decreased body weight, and blood in faeces were observed in the DSS group. DSS treatment increased the spleen weight and damaged the colon tissue. These inflammatory indices were inhibited by HJ treatment. Amplicon sequencing of the 16S rDNA (V4) gene of the caecal content revealed a decrease in the alpha diversity (Simpson index D) in the DSS treatment group compared to the control group. The abundance of caecal Desulfovibrio, an inflammation-related genus, was higher and the caecal Lachnospiraceae and Bacteroides levels were lower in the DSS-treated mice than those in the control mice. However, HJ suppressed the DSS-induced changes in the caecal microbiota. HJ intake contributes to the reduction in inflammation and maintenance of the gut microbiota. However, the strong antioxidant properties of phenolic compounds and fermentability of water-soluble dietary fibres in HJ and their relationship with other functional properties warrant further investigation.

S100a10 deficiency in neutrophils aggravates ulcerative colitis in mice

Background and aimsS100a10 is a member of the S100 family of proteins, which plays a key role in the depression and tumor metastasis. However, the role of S100a10 is unclear in ulcerative colitis. MethodsThe effect of S100a10 was assessed using a murine ulcerative colitis model which was accompanied by parameters including body weight loss, disease activity index, histological score, colon weight and length. The quantity and role of immune cells was determined by flow cytometry and bone marrow chimeric mice. Neutrophils depletion, adoptive cell transfer and conditional knockout mice were used to ascertain which cells played the key role in ulcerative colitis. The function of neutrophils was evaluated by migration assay, phagocytosis assay, multiplex immunoassay and real-time PCR. ResultsIn this study, our data showed that S100a10-/- mice were prone to ulcerative colitis induced by dextran sodium sulfate. Neutrophils number increased in colon of S100a10-/- mice after dextran sodium sulfate treatment significantly. Meanwhile, adoptive transfer of neutrophils from wild type mice partially decreased the susceptibility of S100a10-/- mice to dextran sodium sulfate. There was no difference in ulcerative colitis between the groups of S100a10-/- mice without neutrophils and wild type mice. Finally, we found that S100a10-/- neutrophils had stronger function in secretion and synthesis of inflammatory factor. ConclusionsIn one word, these results suggest that S100a10 has a role in inhibiting the pathogenesis of ulcerative colitis through regulation of neutrophils function.

Chicoric Acid Effectively Mitigated Dextran Sulfate Sodium (DSS)-Induced Colitis in BALB/c Mice by Modulating the Gut Microbiota and Fecal Metabolites.

Chicoric acid (CA) has been reported to exhibit biological activities; it remains unclear, however, whether CA could regulate colitis via modulation of the gut microbiota and metabolites. This study aimed to assess CA's impact on dextran sulfate sodium (DSS)-induced colitis, the gut microbiota, and metabolites. Mice were induced with 2.5% DSS to develop colitis over a 7-day period. CA was administered intragastrically one week prior to DSS treatment and continued for 14 days. The microbial composition in the stool was determined using 16S rRNA sequencing, while non-targeted metabolomics was employed to analyze the metabolic profiles of each mouse group. The results show that CA effectively alleviated colitis, as evidenced by an increased colon length, lowered disease activity index (DAI) and histological scores, and decreased tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) expression levels. CA intervention restored the structure of gut microbiota. Specifically, it decreased the abundance of Bacteroidetes and Cyanobacteria at the phylum level and Bacteroides, Rosiarcus, and unclassified Xanthobacteraceae at the genus level, and increased the abundance of unclassified Lachnospiraceae at the genus level. Metabolomic analysis revealed that CA supplementation reversed the up-regulation of asymmetric dimethylarginine, N-glycolylneuraminic acid, and N-acetylneuraminic acid, as well as the down-regulation of phloroglucinol, thiamine, 4-methyl-5-thiazoleethanol, lithocholic acid, and oxymatrine induced by DSS. Our current research provides scientific evidence for developing CA into an anti-colitis functional food ingredient. Further clinical trials are warranted to elucidate the efficacy and mechanism of CA in treating human inflammatory bowel disease (IBD).

Gut microbiota dysbiosis deteriorates immunoregulatory effects of tryptophan via colonic indole and LBP/HTR2B-mediated macrophage function.

Tryptophan (Trp) has been shown to regulate immune function by modulating gut serotonin (5-HT) metabolism and signaling. However, the mechanisms underlying the microbial modulation of gut 5-HT signaling in gut inflammation with gut microbiota dysbiosis require further investigation. Here, we investigated the effects of Trp supplementation on the composition and metabolism of the gut microbiome and 5-HT signaling-related gut immune function using a dextran sodium sulfate (DSS)-induced colitis mouse model coupled with antibiotic exposure. The results showed that antibiotic treatment before but not during DSS treatment decreased the immunoregulatory effects of Trp and aggravated gut inflammation and body weight loss in mice. Metagenomic analysis revealed that the fecal microbiota transplantation of Trp-enriched gut microbiota to recipient mice subject to antibiotic pre-exposure and DSS treatment alleviated inflammation by increasing the relative abundances of Lactobacillus and Parabacteroides and the microbial production of indole coupled with the activation of the 5-HT receptor 2B (HTR2B) in the colon. Transcriptomic analysis showed that HTR2B agonist administration strengthened the beneficial effects of Trp in DSS-induced colitis mice with antibiotic exposure by reducing gut lipopolysaccharide-binding protein (LBP) production, IκB-α/nuclear factor-κB signaling, and M1 macrophage polarization. Indole treatment reduced LBP production and M1 macrophage polarization both in mice with DSS-induced colitis and in lipopolysaccharide-treated mouse macrophages; however, the HTR2B antagonist reversed the effects of indole. Our findings provide the basis for developing new dietary and therapeutic interventions to improve gut microbiota dysbiosis-associated inflammatory gut disorders and diseases.

Transient gestational hypothyroxinemia accelerates and enhances ulcerative colitis-like disorder in the male offspring.

Gestational hypothyroxinemia (HTX) is a condition that occurs frequently at the beginning of pregnancy, and it correlates with cognitive impairment, autism, and attentional deficit in the offspring. Evidence in animal models suggests that gestational HTX can increase the susceptibility of the offspring to develop strong inflammation in immune-mediated inflammatory diseases. Ulcerative colitis (UC) is a frequent inflammatory bowel disease with unknown causes. Therefore, the intensity of ulcerative colitis-like disorder (UCLD) and the cellular and molecular factors involved in proinflammatory or anti-inflammatory responses were analyzed in the offspring gestated in HTX (HTX-offspring) and compared with the offspring gestated in euthyroidism (Control-offspring). Gestational HTX was induced by the administration of 2-mercapto-1-methylimidazole in drinking water to pregnant mice during E10-E14. The HTX-offspring were induced with UCLD by the acute administration of dextran sodium sulfate (DSS). The score of UCLD symptomatology was registered every day, and colon histopathology, immune cells, and molecular factors involved in the inflammatory or anti-inflammatory response were analyzed on day 6 of DSS treatment. The HTX-offspring displayed earlier UCLD pathological symptoms compared with the Control-offspring. After 6 days of DSS treatment, the HTX-offspring almost doubled the score of the Control-offspring. The histopathological analyses of the colon samples showed signs of inflammation at the distal and medial colon for both the HTX-offspring and Control-offspring. However, significantly more inflammatory features were detected in the proximal colon of the HTX-offspring induced with UCLD compared with the Control-offspring induced with UCLD. Significantly reduced mRNA contents encoding for protective molecules like glutamate-cysteine ligase catalytic subunit (GCLC) and mucin-2 (MUC-2) were found in the colon of the HTX-offspring as compared with the Control-offspring. Higher percentages of Th17 lymphocytes were detected in the colon tissues of the HTX-offspring induced or not with UCLD as compared with the Control-offspring. Gestational HTX accelerates the onset and increases the intensity of UCLD in the offspring. The low expression of MUC-2 and GCLC together with high levels of Th17 Lymphocytes in the colon tissue suggests that the HTX-offspring has molecular and cellular features that favor inflammation and tissue damage. These results are important evidence to be aware of the impact of gestational HTX as a risk factor for UCLD development in offspring.

DSS treatment does not affect murine colonic microbiota in absence of the host

ABSTRACT The prevalence of inflammatory bowel disease (IBD) is rising globally; however, its etiology is still not fully understood. Patient genetics, immune system, and intestinal microbiota are considered critical factors contributing to IBD. Preclinical animal models are crucial to better understand the importance of individual contributing factors. Among these, the dextran sodium sulfate (DSS) colitis model is the most widely used. DSS treatment induces gut inflammation and dysbiosis. However, its exact mode of action remains unclear. To determine whether DSS treatment induces pathogenic changes in the microbiota, we investigated the microbiota-modulating effects of DSS on murine microbiota in vitro. For this purpose, we cultured murine microbiota from the colon in six replicate continuous bioreactors. Three bioreactors were supplemented with 1% DSS and compared with the remaining PBS-treated control bioreactors by means of microbiota taxonomy and functionality. Using metaproteomics, we did not identify significant changes in microbial taxonomy, either at the phylum or genus levels. No differences in the metabolic pathways were observed. Furthermore, the global metabolome and targeted short-chain fatty acid (SCFA) quantification did not reveal any DSS-related changes. DSS had negligible effects on microbial functionality and taxonomy in vitro in the absence of the host environment. Our results underline that the DSS colitis mouse model is a suitable model to study host–microbiota interactions, which may help to understand how intestinal inflammation modulates the microbiota at the taxonomic and functional levels.

BRAFV600E mutation and DSS treatment synergize to induce cecal tumor formation in mice

BRAF mutation is a driver mutation in colorectal cancer (CRC), and BRAFV600E mutation is found in 10–15 % of all CRCs. BRAF mutant CRCs in patients are primarily localized in the right colon, including the cecum. However, in the Vill-Cre;BRAFV600E/+ mice, adenomas mainly developed in the small intestines of the mice, and no tumor formed in the cecum. The mice model of BRAFV600E-mutant CRC with tumors in the cecum is lacking. Dextran Sulfate Sodium (DSS) treatment induces colitis in mice. Acute DSS treatment does not lead to tumor formation. We show that DSS treatment and BRAFV600E mutation synergistically induced cecal tumorigenesis, and cecal tumors formed within three months after five-day DSS treatment. The location of the adenomas supports the patient relevance of the model. Our BRAFV600E/DSS model provides a valuable in vivo model for future identification and validation of novel therapeutic approaches for treating BRAF-mutant CRC. Our results are consistent with the notion that BRAFV600E mutation is an oncogenic event that can shift controlled regeneration to unrestrained oncogenesis.

Protective Effects of Imatinib on a DSS-induced Colitis Model Through Regulation of Apoptosis and Inflammation.

Inflammatory bowel disease (IBD) is characterized by dysregulated immune responses and a multifactorial etiology. While imatinib has demonstrated efficacy in the treatment of immune-related diseases, its potential effects in IBD treatment remain underexplored. This study aimed to investigate the therapeutic effects of imatinib in colitis treatment. A dextran sulfate sodium (DSS)-induced colitis model was used to mimic IBD in mice. Imatinib was administered orally to mice simultaneously with DSS treatment. The effects of imatinib on DSS-induced colitis were evaluated by analyzing colitis-related pathology, including the disease activity index (DAI), histological lesions, inflammatory markers, and tight junction integrity. Additionally, western blot analysis and quantitative real-time polymerase chain reaction were used to assess inflammatory markers, tight-junction proteins, and cell death. In the DSS-induced colitis model, imatinib treatment exerted protective effects by attenuating weight loss, restoring colon length, reducing spleen weight, and improving the DAI score and histological lesions. Additionally, imatinib reduced the level of proinflammatory cytokines, including TNF-α, IL-6, and IL-1β. Furthermore, imatinib treatment restored tight-junction integrity and decreased the expression of apoptosis marker proteins. Overall, imatinib treatment significantly alleviated the symptoms of DSS-induced colitis by influencing the expression of proinflammatory cytokines, tight junction proteins, and apoptotic markers in mice. These findings highlight imatinib as a potential therapeutic candidate for IBD.

WNT2B Deficiency Causes Enhanced Susceptibility to Colitis Due to Increased Inflammatory Cytokine Production

Background and aimsHumans with WNT2B deficiency have severe intestinal disease, including significant inflammatory injury, highlighting a critical role for WNT2B. We sought to understand how WNT2B contributes to intestinal homeostasis. MethodsWe investigated the intestinal health of Wnt2b knock out (KO) mice. We assessed the baseline histology and health of the small intestine and colon, as well as the impact of inflammatory challenge using dextran sodium sulfate (DSS). We also evaluated human intestinal tissue. ResultsMice with WNT2B deficiency had normal baseline histology but enhanced susceptibility to DSS colitis due to an increased early injury response. While ISC markers were decreased, epithelial proliferation was similar to controls. Wnt2b KO mice showed an enhanced inflammatory signature after DSS treatment. Wnt2b KO colon and human WNT2B-deficient organoids both had increased levels of CXCR4 and IL6, and biopsy tissue from humans showed increased neutrophils. ConclusionWNT2B is important for regulation of inflammation in the intestine. Absence of WNT2B leads to increased expression of inflammatory cytokines and increased susceptibility to gastrointestinal inflammation, particularly in the colon.

C-Reactive Protein Is Not the Driver Factor in Ulcerative Colitis.

Purpose: C-reactive protein (CRP) functions as a nonspecific marker in various inflammatory disorders, particularly in evaluating the efficacy of pharmacological treatments in patients with ulcerative colitis. The existing body of evidence does not offer adequate support for the direct implication of CRP in modulating the advancement of ulcerative colitis. Methods: Our study employed a rigorous mouse model. An ulcerative colitis mouse model was established by subjecting CRP-deficient mice to dextran sulfate sodium (DSS) treatment. The phenotype of the mice, which encompassed parameters such as body weight, colon length, and spleen weight, was meticulously evaluated. Additionally, various physiological and biochemical indicators were assessed, including colon histopathology, expression levels of inflammatory factors, and staining of the intestinal mucus layer. Results: The absence of CRP did not significantly affect the phenotype, physiological characteristics, and biochemical indices in a mouse model of ulcerative colitis compared to mice with wild-type CRP. Additionally, eliminating intestinal bacteria flora interference through antibiotic treatment revealed that mice lacking CRP did not demonstrate any notable variations in the ulcerative colitis model. Meanwhile, the survival rate of mice lacking CRP did not exhibit a statistically significant difference compared to wild-type mice. Conclusion: The results of our study suggest that CRP may not directly mediate ulcerative colitis. Instead, it is more likely to be a bystander that is present alongside with elevated inflammatory factors. Further investigation is warranted to determine the precise role of CRP in humans, given the significant limitations associated with the use of mouse models.

Optogenetic Activation of Cholinergic Enteric Neurons Reduces Inflammation in Experimental Colitis

Background & AimsIntestinal inflammation is associated with loss of enteric cholinergic neurons. Given the systemic anti-inflammatory role of cholinergic innervation, we hypothesized that enteric cholinergic neurons similarly possess anti-inflammatory properties and may represent a novel target to treat inflammatory bowel disease (IBD). MethodsMice were fed 2.5% dextran sodium sulfate (DSS) for seven days to induce colitis. Cholinergic enteric neurons, which express choline acetyltransferase (ChAT), were focally ablated in the mid-colon of ChAT::Cre;R26-iDTR (ChAT-iDTR) mice by local injection of diphtheria toxin prior to colitis induction. Activation of enteric cholinergic neurons was achieved using ChAT::Cre;R26-ChR2 (ChAT-ChR2) mice, in which ChAT+ neurons express channelrhodopsin-2 (ChR2), with daily blue light stimulation (BLS) delivered via an intracolonic probe during the 7 days of DSS treatment. Colitis severity, ENS structure, and smooth muscle contractility were assessed by histology, immunohistochemistry, qPCR, organ bath, and electromyography. In vitro studies assessed the anti-inflammatory role of enteric cholinergic neurons on cultured muscularis macrophages. ResultsAblation of ChAT+ neurons in DSS-treated mice exacerbated colitis, as measured by weight loss, colon shortening, histologic inflammation, and CD45+ cell infiltration, and led to colonic dysmotility. Conversely, optogenetic activation of enteric cholinergic neurons improved colitis, preserved smooth muscle contractility, protected against loss of cholinergic neurons, and reduced proinflammatory cytokine production. Both ACh and optogenetic cholinergic neuron activation in vitro reduced proinflammatory cytokine expression in LPS-stimulated muscularis macrophages. ConclusionsThese findings demonstrate that enteric cholinergic neurons have an anti-inflammatory role in the colon and should be explored as a potential IBD treatment.

Hippocampal and gut AMPK activation attenuates enterocolitis-like symptoms and co-occurring depressive-like behavior in ulcerative colitis model mice: Involvement of brain-gut autophagy

Patients with inflammatory bowel disease, including ulcerative colitis (UC) and Crohn's disease, have a high incidence of psychiatric disorders, including depression and anxiety. However, the underlying pathogenic mechanism remains unknown. Dextran sulfate sodium (DSS)-treated mice, a model of UC, exhibit depressive-like behavior and reduced adenosine monophosphate-activated protein kinase (AMPK) activity, which regulates various physiological functions in the brain and gut. However, comprehensive studies on UC pathophysiology with co-occurring depression focused on brain-gut AMPK activity are lacking. Therefore, we aimed to investigate whether resveratrol (RES), an AMPK activator, prevented DSS-induced UC-like symptoms and depressive-like behavior. DSS treatment induced UC-like pathology and depressive-like behavior, as assessed via the tail suspension test. Moreover, western blotting and immunohistochemical studies revealed that DSS increased p-p70S6 kinase (Thr389), p62, tumor necrosis factor-α, interleukin (IL)-1β, IL-18, NLR family pyrin domain containing 3 (NLRP3), cleaved caspase-1, cleaved Gasdermin-D (GSDMD), and cleaved caspase-3 expression levels in the rectum and hippocampus, and increased CD40, iNOS, and Kelch-like ECH-associated protein 1 expression levels, and the number of Iba1-positive cells in the hippocampus, and decreased p-AMPK and LC3II/I expression levels, and the number of NF-E2-related factor 2 (Nrf2)-positive cells, and reduced neurogenesis in the hippocampus. These changes were reversed by the RES administration. RES also enhanced PGC1α and SOD1 expression in the hippocampus of DSS-treated male mice. Moreover, NLRP3 staining was observed in the neurons and microglia, and cleaved GSDMD staining in neurons in the hippocampus of DSS-treated mice. Notably, RES prevented UC-like pathology and depressive-like behavior and enhancement of autophagy, decreased rectal and hippocampal inflammatory cytokines and inflammasome, and induced the Nrf2-PGC1α-SOD1 pathway in the hippocampus, resulting in neurogenesis in the hippocampal dentate gyrus. Our findings suggest that brain-gut AMPK activation may be an important therapeutic strategy in patients with UC and depression.

Isolation and Characterization of n-3 Polyunsaturated Fatty Acids in Enteromorpha prolifera Lipids and Their Preventive Effects on Ulcerative Colitis in C57BL/6J Mice.

Enteromorpha prolifera (EP) is a green alga that causes green bloom worldwide. This study aimed to isolate and identify n-3 polyunsaturated fatty acids (PUFAs) from EP oil obtained via supercritical fluid extraction (SFE) and to explore its preventive effects against dextran sodium sulfate (DSS)-induced ulcerative colitis in C57BL/6J mice. In EP oil, we found the novel n-3 polyunsaturated fatty acid C16:4n-3 and two unusual fatty acids C18:4n-3 and C16:3n-3, using GC-MS. The administration of EP oil reduced histopathological of symptoms colitis and the shortening of the colon length. Pro-inflammatory cytokines of IL-6 and TNF-α in serum of EP oil treatment were lower than DSS treatment (by 37.63% and 83.52%), and IL-6 gene expression in the colon was lower in than DSS group by 48.28%, and IL-10 in serum was higher than DSS group by 2.88-fold. Furthermore, the protein expression of p-STAT3 by the EP oil treatment was significantly reduced compared with DSS treatment group by 73.61%. Lipidomics study suggested that phosphatidylcholine and phosphatidylethanolamine were positively associated with the anti-inflammatory cytokine IL-10, while cholesteryl ester and sphingomyelin were negatively related to inflammation cytokines in the EP oil group. The present results indicated that EP oil rich in n-3 PUFA contains a novel fatty acid C16:4n-3, as well as two uncommon fatty acids C18:4n-3 and C16:3n-3. EP oil could prevent DSS-induced ulcerative colitis by regulating the JAK/STAT pathway and lipid metabolism.

Immortalized Canine Adipose-Derived Mesenchymal Stem Cells Maintain the Immunomodulatory Capacity of the Original Primary Cells.

Mesenchymal stem cells (MSCs) are a promising cell source for stem cell therapy of intractable diseases in veterinary medicine, but donor-dependent cellular heterogeneity is an issue that influences therapeutic efficacy. Thus, we previously established immortalized cells that maintain the fundamental properties of primary cells, but functional evaluation had not been performed. Therefore, we evaluated the immunomodulatory capacity of the immortalized canine adipose-derived MSCs (cADSCs) in vitro and in vivo to investigate whether they maintain primary cell functions. C57BL/6J mice were treated with dextran sulfate sodium (DSS) to induce colitis, injected intraperitoneally with immortalized or primary cADSCs on day 2 of DSS treatment, and observed for 10 days. Administration of immortalized cADSCs improved body weight loss and the disease activity index (DAI) in DSS-induced colitic mice by shifting peritoneal macrophage polarity from the M1 to M2 phenotype, suppressing T helper (Th) 1/Th17 cell responses and inducing regulatory T (Treg) cells. They also inhibited the proliferation of mouse and canine T cells in vitro. These immunomodulatory effects were comparable with primary cells. These results highlight the feasibility of our immortalized cADSCs as a cell source for stem cell therapy with stable therapeutic efficacy because they maintain the immunomodulatory capacity of primary cells.

Ethyl acetate extract of Terminalia chebula alleviates DSS-induced ulcerative colitis in C57BL/6 mice.

Background: The Chinese pharmacopeia records Terminalia chebula as effective in treating prolonged diarrhea and dysentery, blood in the stool, and prolapse. Modern pharmacological research proves it has multiple pharmacological benefits, including antioxidant, anti-inflammatory, analgesic, hepatoprotective, neuroprotective, and other properties. Objectives: This study aims to clarify the role of Terminalia chebula's ethyl acetate extract (TCEA) on ulcerative colitis (UC) induced by dextran sodium sulfate (DSS) in mice, as well as explore the potential mechanism of action. Materials and methods: The variation of different extracts of T. chebula was detected using the HPLC technique, and the main components in TCEA were identified. DSS was used to establish a mouse model to mimic the physiological state of UC in humans; the alleviating effect of TCEA and positive control 5-ASA on UC mice were evaluated by gavage treatment. Disease progression was assessed by monitoring the mouse's weight change and disease activity index (DAI). The changes in colon tissue were estimated by measuring colon length, HE, and AB-PAS staining and detecting oxidative stress parameters. The results draw from Western blot and real-time PCR showed the TLR4/MyD88/NF-κB pathway may involve in the anti-inflammatory activity of TCEA. Furthermore, the gut flora sequencing technique was employed to monitor the differentiation of intestinal microbiota of mice induced by DSS and TCEA treatment. Results: TCEA significantly lowered DAI scores and inhibited the weight loss and colonic shortening induced by DSS. The colon histomorphology and oxidative stress levels were enhanced after TCEA treatment compared with DSS induced UC group. TCEA attenuated the inflammatory response by regulating TLR4/MyD88/NF-κB pathway activation. Intestinal flora sequencing showed that DSS and TCEA greatly impacted mice's composition and diversity of intestinal microorganisms. But TCEA increased the abundance of Bacteroidetes and decreased the abundance of Firmicutes and Proteobacteria compared with the DSS group, which contributed a lot to returning the intestinal flora to a balanced state. Conclusion: This study confirms the alleviating effect of TCEA on UC and provides new ideas for developing TCEA into a new drug to treat UC.