Dextran Sulfate Sodium Colitis Research Articles

TiO2 nanoparticles abrogate the protective effect of the Crohn’s disease-associated variation within the PTPN22 gene locus

ObjectiveInflammatory bowel disease (IBD) is a multifactorial condition driven by genetic and environmental risk factors. A genetic variation in the protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene has been...

Treatment with butyrate alleviates dextran sulfate sodium and Clostridium difficile-induced colitis by preventing activity of Th17 cells via regulation of SIRT1/mTOR in mice

Inflammatory bowel disease (IBD) patients are particularly vulnerable to infection with Clostridium difficile infection (CDI).Available treatments of IBD with CDI have not effective. Butyrate, the metabolites of microbiota, plays a vital role in maintaining immune homeostasis and potential drugs for treatment of IBD with CDI. The aim of this study was to investigate the effect of butyrate on IBD with CDI. Mice were given dextran sulfate sodium (DSS) and were infected with C. difficile (CD). Butyrate was treated during the study period. Butyrate protected from DSS+CD induced colitis by improving weight loss, survival, colon shorten, activity index score, and suppressing the expression of proinflammatory cytokines including IL-6, IL-17, TNF-α, IL-1β as well as regulating Th17/Treg balance through activation of SIRT1/mTOR. Besides, SR1001, an inhitor of the orphan nuclear receptors retinoic acid-related receptor γt, which is a transcription factor specific to the formation of Th17 cells can suppress the Th17 development and alleviate the DSS+CD induced colitis in mice. Notably, the therapeutic effect of butyrate was revered when disease mice treated with butyrate and Ex-527, a SIRT1 inhibitor. Taken together, we demonstrate that butyrate alleviates dextran sulfate sodium and clostridium difficile induced colitis by preventing Th17 through activation of SIRT1/mTOR.

Protective effect of α7 nicotinic acetylcholine receptor activation on experimental colitis and its mechanism

BackgroundInflammatory bowel disease (IBD) is a common chronic remitting disease with no satisfactory treatment. The aim of this study was to investigate the protective effect of α7 nicotinic acetylcholine receptor (α7nAChR), and to determine the underlying mechanism of its activity.MethodsThe expression and distribution of α7nAChR in the intestinal tissue of patients with ulcerative colitis and Crohn’s disease were analyzed. The effects of vagal excitation on murine experimental colitis were investigated. The colitis model was induced in C57BL/6 mice by the administration of 3% dextran sulfate sodium (DSS). The therapeutic group received treatment with the α7nAChR agonist PNU-282987 by intraperitoneal injection.ResultsOur results showed that there was significantly increased expression of α7nAChR in colitis and Crohn’s disease intestinal tissue, and its expression was mainly located in macrophages and neutrophils, which were extensively infiltrated in the disease status. Treatment with an α7nAChR agonist potently ameliorated the DSS-induced illness state, including weight loss, stool consistency, bleeding, colon shortening, and colon histological injury. α7nAChR agonist exerted anti-inflammatory effects in DSS colitis mice by suppressing the secretion of multiple types of proinflammatory factors, such as IL6, TNFα, and IL1β, and it also inhibited the colonic infiltration of inflammatory cells by blocking the DSS-induced overactivation of the NF-κB and MAPK signaling pathways. Mechanistically, activation of α7nAChR decreased the number of infiltrated M1 macrophages in the colitis intestine and inhibited the phagocytosis ability of macrophages, which were activated in response to LPS stimulation.ConclusionThus, an α7nAChR agonist ameliorated colonic pathology and inflammation in DSS-induced colitis mice by blocking the activation of inflammatory M1 macrophages.

Characterization of Maladaptive Processes in Acute, Chronic and Remission Phases of Experimental Colitis in C57BL/6 Mice.

Inflammatory bowel disease (IBD) is a chronic recurrent inflammatory disease with unknown etiology. Dextran sulfate sodium (DSS) induced colitis is a widely used mouse model in IBD research. DSS colitis involves activation of the submucosal immune system and can be used to study IBD-like disease characteristics in acute, chronic, remission and transition phases. Insight into colon inflammatory parameters is needed to understand potentially irreversible adaptations to the chronification of colitis, determining the baseline and impact of further inflammatory episodes. We performed analyses of non-invasive and invasive colitis parameters in acute, chronic and remission phases of the DSS colitis in C57BL/6 mice. Non-invasive colitis parameters poorly reflected inflammatory aspects of colitis in chronic remission phase. We found invasive inflammatory parameters, positively linked to repeated DSS-episodes, such as specific colon weight, inflamed colon area, spleen weight, absolute cell numbers of CD4+ and CD8+ T cells as well as B cells, blood IFN-γ level, colonic chemokines BLC and MDC as well as the prevalence of Turicibacter species in feces. Moreover, microbial Lactobacillus species decreased with chronification of disease. Our data point out indicative parameters of recurrent gut inflammation in context of DSS colitis.

Blocking DCIR mitigates colitis and prevents colorectal tumors by enhancing the GM-CSF-STAT5 pathway.

Dendritic cell immunoreceptor (DCIR; Clec4a2), a member of the C-type lectin receptor family, plays important roles in homeostasis of the immune and bone systems. However, the intestinal role of this molecule is unclear. Here, we show that dextran sodium sulfate (DSS)-induced colitis and azoxymethane-DSS-induced intestinal tumors are reduced in Clec4a2-/- mice independently of intestinal microbiota. STAT5 phosphorylation and expression of Csf2 and tight junction genes are enhanced, while Il17a and Cxcl2 are suppressed in the Clec4a2-/- mouse colon, which exhibits reduced infiltration of neutrophils and myeloid-derived suppressor cells. Granulocyte-macrophage colony-stimulating factor (GM-CSF) administration ameliorates DSS colitis associated with reduced Il17a and enhanced tight junction gene expression, whereas anti-GM-CSF exacerbates symptoms. Furthermore, anti-NA2, a ligand for DCIR, ameliorates colitis and prevents colorectal tumors. These observations indicate that blocking DCIR signaling ameliorates colitis and suppresses colonic tumors, suggesting DCIR as a possible target for the treatment of these diseases.

Therapeutic Potential of Quercetin Loaded Nanoparticles: Novel Insights in Alleviating Colitis in an Experimental DSS Induced Colitis Model.

Oxidative stress is considered the main etiologic factor involved in inflammatory bowel disease (IBD). Integration of nanocarriers for natural therapeutic agents with antioxidant and anti-inflammatory potential is a novel promising candidate for curing IBD. Herein, the colonic antioxidant and anti-inflammatory effects of different concentrations of quercetin nanoparticles (QT-NPs) were evaluated using a dextran sulfate sodium (DSS)-induced colitis model. Following colitis induction, the efficacy and mechanistic actions of QT-NPs were evaluated by assessing lesion severity, molecular aids controlling oxidative stress and inflammatory response, and histopathological and immunohistochemistry examination of colonic tissues. Administration of QT-NPs, especially at higher concentrations, significantly reduced the disease activity index and values of fecal calprotectin marker compared to the colitic group. Colonic oxidant/antioxidant status (ROS, H2O2, MDA, SOD, CAT, GPX and TAC) was restored after treatment with higher concentrations of QT-NPs. Moreover, QT-NPs at levels of 20 mg/kg and, to a lesser extent, 15 mg/kg reduced Nrf2 and HO-1 gene expression, which was in line with decreasing the expression of iNOS and COX2 in colonic tissues. Higher concentrations of QT-NPs greatly downregulated pro-inflammatory cytokines; upregulated genes encoding occludin, MUC-2 and JAM; and restored the healthy architectures of colonic tissues. Taken together, these data suggest that QT-NPs could be a promising alternative to current IBD treatments.

Inhibition of TLR4 Suppresses the Inflammatory Response in Inflammatory Bowel Disease (IBD) by Modulating the PDK1-Induced Metabolism Reprogramming via a m6A-Denpendent Manner.

Objective To investigate the role of TLR4 and PDK1 genes in IBD. Methods The DSS mouse model was established by inducing BALB/C with 5% DSS solution. The behavior of DSS mice was detected, and the m6A modification was detected by m6A methylation chip. At the same time, the expressions of TLR and PDK1 were detected by fluorescence real-time quantitative PCR. Results The results showed that the model of dextran sodium sulfate colitis in mice was successful, and the colon membrane of mice had obvious naked eye inflammation. Through comparison, it was found that there were differences in m6A modification between the blank group and the model group, and compared with the blank group, the expression of PKD1 in DSS group was significantly reduced and the expression of TLR4 was significantly increased. Conclusion TLR4 inhibition inhibits the inflammatory response in inflammatory bowel disease (IBD) in a m6A-dependent manner by regulating PDK1-induced metabolic reprogramming.

The Protective Effect of Sulforaphane on Dextran Sulfate Sodium-Induced Colitis Depends on Gut Microbial and Nrf2-Related Mechanism.

Sulforaphane (SFN), an isothiocyanate present in cruciferous vegetables such as broccoli and brussels sprouts, has a variety of biological functions. This study was undertaken to assess the potential efficacy of SFN in ameliorating dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice and to elucidate the underlying mechanisms. UC was induced in mice with administration of 2% DSS in drinking water for 7 days. Male C57BL/6 mice were treated with Mesalazine (50 and 100 mg/kg body weight) and various doses of SFN (2.5, 5, 10, and 20 mg/kg body weight). In DSS colitis mice, the hallmarks of disease observed as shortened colon lengths, increased disease activity index (DAI) scores and pathological damage, higher proinflammatory cytokines and decreased expression of tight junction proteins, were alleviated by SFN treatment. SFN also partially restored the perturbed gut microbiota composition and increased production of volatile fatty acids (especially caproic acid) induced by DSS administration. The heatmap correlation analysis indicated that Lactobacillus johnsonii, Bacteroides acidifaciens, unclassified Rikenellaceae RC9, and unclassified Bacteroides were significantly correlated with disease severity. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2), Signal Transducer and Activator of Transcription 3 (STAT3), and Phase II enzyme UDP-glucuronosyltransferase (UGT) were involved in the protective effect of SFN against DSS-induced colitis. This study's findings suggest that SFN may serve as a therapeutic agent protecting against UC.

BATF3 Protects Against Metabolic Syndrome and Maintains Intestinal Epithelial Homeostasis.

The intestinal immune system and microbiota are emerging as important contributors to the development of metabolic syndrome, but the role of intestinal dendritic cells (DCs) in this context is incompletely understood. BATF3 is a transcription factor essential in the development of mucosal conventional DCs type 1 (cDC1). We show that Batf3-/- mice developed metabolic syndrome and have altered localization of tight junction proteins in intestinal epithelial cells leading to increased intestinal permeability. Treatment with the glycolysis inhibitor 2-deoxy-D-glucose reduced intestinal inflammation and restored barrier function in obese Batf3-/- mice. High-fat diet further enhanced the metabolic phenotype and susceptibility to dextran sulfate sodium colitis in Batf3-/- mice. Antibiotic treatment of Batf3-/- mice prevented metabolic syndrome and impaired intestinal barrier function. Batf3-/- mice have altered IgA-coating of fecal bacteria and displayed microbial dysbiosis marked by decreased obesity protective Akkermansia muciniphila, and Bifidobacterium. Thus, BATF3 protects against metabolic syndrome and preserves intestinal epithelial barrier by maintaining beneficial microbiota.

Label-Free Characterization and Quantification of Mucosal Inflammation in Common Murine Colitis Models With Multiphoton Imaging

Clinical challenges in inflammatory bowel diseases require microscopic in vivo evaluation of inflammation. Here, label-free imaging holds great potential, and recently, our group demonstrated the advantage of using in vivo multiphoton endomicroscopy for longitudinal animal studies. This article extends our previous work by in-depth analysis of label-free tissue features in common colitis models quantified by the multiphoton colitis score (MCS). Fresh mucosal tissues were evaluated from acute and chronic dextran sulfate sodium (DSS), TNBS, oxazolone, and transfer colitis. Label-free imaging was performed by using second harmonic generation and natural autofluorescence. Morphological changes in mucosal crypts, collagen fibers, and cellularity in the stroma were analyzed and graded. Our approach discriminated between healthy (mean MCS = 2.5) and inflamed tissue (mean MCS > 5) in all models, and the MCS was validated by hematoxylin and eosin scoring of the same samples (85.2% agreement). Moreover, specific characteristics of each phenotype were identified. While TNBS, oxazolone, and transfer colitis showed high cellularity in stroma, epithelial damage seemed specific for chronic, acute DSS and transfer colitis. Crypt deformations were mostly observed in acute DSS. Quantification of label-free imaging is promising for in vivo endoscopy. In the future, this could be valuable for monitoring of inflammatory pathways in murine models, which is highly relevant for the development of new inflammatory bowel disease therapeutics.

The Efficacy of Encapsulated Gamma-Cyclodextrin/Tributyrin on Growth and Inflammation in a Dextran Sodium Sulfate-Challenge Piglet Model

ObjectivesInflammatory bowel diseases are common in adults, and their incidence is increasing in children. Butyrate, a short chain fatty acid, can improve gut health, but its bitterness limits incorporation into foods. Herein, the efficacy of tributyrin (TB), a butyrate analog, encapsulated with ɣ-cyclodextrin (ɣ-CD) on growth and intestinal inflammation in a piglet model of dextran-sodium sulfate (DSS)-induced colitis was investigated. MethodsTwo-day-old piglets were randomized to three diets: control (formula alone, CON, N = 41), CD (CON + 9.0 mM ɣ-CD, N = 41), or CDTB (CON + 9.0 mM ɣ-CD/TB, N = 43). Half of the piglets in each group received DSS (1.25 g/kg body weight) from postnatal day (PND) 14 to 18. Blood and intestinal samples were collected on PND 19 and 27. IL-6 and TNF-α concentration in serum and colon mucosa were assessed by ELISA and IL-6, TNF-α, IL-10 and IFN-γ gene expression in colonic tissue were measured by qPCR. A quantitative histological grading system was used to assess 4 independent parameters: epithelial lining, cell infiltration, crypt damage and extent of the intestinal section affected. ResultsAverage daily weight gain (WG) between PND2-10 and 10–19 were affected by diet (P < 0.05), while colitis led to lower WG from PND19-27. A diet and colitis interaction indicated that after PND22 CDTB-COL piglets weighed less than CON and CD (P = 0.051). Diet had no impact on the descending colon (DC) morphology in the colitis animals, but the severity of the DC inflammation increased from PND19 and 27 (P < 0.0001). TNF-α and IL-6 concentrations were elevated in the ascending colon (AC) at PND19, but by PND27 concentrations were similar to non-colitis levels. A similar pattern was found in the DC, except that IL-6 remained elevated on PND27. IL-6, TNF-α and IFN-γ gene expression were significantly higher in the DC of colitis vs. non-colitis animals on PND27. Diet and colitis had no effect on serum TNF-α and IL-6. ConclusionsThe piglet as a model of DSS colitis is a feasible alternative to rodents. Dietary ɣ-CD/TB reduced growth rate and did not ameliorate the inflammatory process of DSS-induced colitis in neonatal pigs. Herein, oral administration of encapsulated TB did not reduce DSS-induced tissue damage or inflammation, however, additional studies are needed to confirm these observations. Funding SourcesNIFA, ISDA 2017–67,017-26,519.

An oral “Super probiotics” with versatile self-assembly adventitia for enhanced intestinal colonization by autonomous regulating the pathological microenvironment

Transplanting beneficial bacteria to gut microbiome can positively modulate microbiome composition and is a promising strategy to prevent and treat diseases. However, oral probiotic delivery is challenged not only by the physiological microenvironment, but also by pathological microenvironment. Herein, we designed a Super Gut Microorganism (SGM) encapsulated with versatile self-assembly coating for enhanced intestinal colonization. SGM has a rapidly self-assembling coating of tannic acid and poloxamer 188 that not only resists the attack of the physiological microenvironment but more importantly, autonomously modulates the pathological microenvironment (e.g., scavenging inflammation-mediated ROS and taking iron away from pathogenic bacteria), which improves probiotic survival. In addition, the artificial coat mediates strong intestinal mucosal adhesion, enhancing the intestine colonization of probiotics especially in disease. SGM significantly improved the efficacy in the prevention and treatment of colitis in vivo. In dextran sulfate sodium (DSS) colitis mice, SGM showed an excellent anti-inflammatory effect, capacity to restore intestinal barrier functions, and to prompt the balance of gut flora. In Salmonella enterica serovar Typhimurium (STm) colitis mice, treatment with SGM resulted in 6.8-times less STm compared to uncoated probiotics. The SGM presented here are a new resource to create novel probiotic systems to treat and prevent microbiome related diseases.

IL-38 Gene Deletion Worsens Murine Colitis.

IL-38 is a recently discovered cytokine and member of the IL-1 Family. In the IL-1 Family, IL-38 is unique because the cytokine is primarily a B lymphocyte product and functions to suppress inflammation. Studies in humans with inflammatory bowel disease (IBD) suggest that IL-38 may be protective for ulcerative colitis or Crohn’s disease, and that IL-38 acts to maintain homeostasis in the intestinal tract. Here we investigated the role of endogenous IL-38 in experimental colitis in mice deficient in IL-38 by deletion of exons 1-4 in C57 BL/6 mice. Compared to WT mice, IL-38 deficient mice subjected to dextran sulfate sodium (DSS) showed greater severity of disease, more weight loss, increased intestinal permeability, and a worse histological phenotype including increased neutrophil influx in the colon. Mice lacking IL-38 exhibited elevated colonic Nlrp3 mRNA and protein levels, increased caspase-1 activation, and the concomitant increased processing of IL-1β precursor into active IL-1β. Expression of IL-1α, an exacerbator of IBD, was also upregulated. Colonic myleloperoxidase protein and Il17a, and Il17f mRNA levels were higher in the IL-38 deficient mice. Daily treatment of IL-38 deficient mice with an NLRP3 inhibitor attenuated diarrhea and weight loss during the recovery phase. These data implicate endogenous IL-38 as an anti-inflammatory cytokine that reduces DSS colitis severity. We propose that a relative deficiency of IL-38 contributes to IBD by disinhibition of the NLRP3 inflammasome.

MarvelD3 Is Upregulated in Ulcerative Colitis and Has Attenuating Effects during Colitis Indirectly Stabilizing the Intestinal Barrier.

In inflammatory bowel disease (IBD), the impaired intestinal barrier is mainly characterized by changes in tight junction protein expression. The functional role of the tight junction-associated MARVEL protein MARVELD3 (MD3) in IBD is yet unknown. (i) In colon biopsies from IBD patients we analyzed MD3 expression and (ii) in human colon HT-29/B6 cells we studied the signaling pathways of different IBD-relevant cytokines. (iii) We generated a mouse model with intestinal overexpression of MD3 and investigated functional effects of MD3 upregulation. Colitis, graded by the disease activity index, was induced by dextran sodium sulfate (DSS) and the intestinal barrier was characterized electrophysiologically. MD3 was upregulated in human ulcerative colitis and MD3 expression could be increased in HT-29/B6 cells by IL-13 via the IL13Rα1/STAT pathway. In mice DSS colitis, MD3 overexpression had an ameliorating, protective effect. It was not based on direct enhancement of paracellular barrier properties, but rather on regulatory mechanisms not solved yet in detail. However, as MD3 is involved in regulatory functions such as proliferation and cell survival, we conclude that the protective effects are hardly targeting the intestinal barrier directly but are based on regulatory processes supporting stabilization of the intestinal barrier.

Using Network Pharmacology and Molecular Docking Technology to Explore the Mechanism of Modified Pulsatilla Decoction in the Treatment of Ulcerative Colitis

Objective: Using network pharmacology and molecular docking technology, our aim was to clarify the biological activity, key targets, and potential pharmacological mechanisms of modified Pulsatilla decoction (MPD) in the treatment of ulcerative colitis (UC). Materials and Methods: The main active ingredients of MPD were screened using the traditional Chinese medicine systems pharmacology platform. UC targets were obtained from the GeneCard, OMIM, DisGeNET, PharmGkb, and DrugBank databases. The common genes of MPD in the treatment of UC were identified by Venn diagram. The visual interactive network diagram of “active ingredient-target-disease” was constructed using the software Cytoscape. We used the STRING database to construct a protein–protein interaction network and analyze the correlation in protein interaction. We conducted gene ontology enrichment analysis and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis for common genes using the Database for Annotation, Visualization, and Integrated Discovery (DAVID) database and R software. Subsequently, the molecular docking verification of ingredients and targets was conducted through Discovery Studio. Last, in vivo experiments were conducted to further verify the findings. Results: A total of 51 active ingredients were screened, involving 141 common genes. The top 5 ingredients in MPD were quercetin, β-sitosterol, luteolin, kaempferol, and stigmasterol. Pathways involved in the treatment of UC include the advanced glycation end products-receptor for advanced glycation end products (AGE-RAGE) signaling pathway, the interleukin-17 (IL-17) signaling pathway, the tumor necrosis factor (TNF) signaling pathway, viral infection-related signaling pathways, and some cancer pathways. Molecular docking showed that the important ingredients of MPD were well docked with mitogen-activated protein kinase 1 (MAPK1), mitogen-activated protein kinase 8 (MAPK8), RAC-alpha serine (AKT1), vascular endothelial growth factor-A (VEGFA), transcription factor AP-1 (JUN), and interleukin-6 (IL-6). Animal experiments showed that MPD could ameliorate the injury and colitis in dextran sulfate sodium (DSS)-induced colitic rats. MPD inhibited the expression of p-p38A and p-MLC in UC rats. Conclusions: MPD has the characteristics of a multisystem, multi-ingredient, and multitarget in the treatment of UC. The possible mechanisms include inhibition of inflammation, apoptosis, oxidation, and tumor gene transcription. MPD may have a protective effect in the treatment of UC.

Obese adipose tissue extracellular vesicles inhibit recovery from dextran sulphate sodium (DSS)‐induced colitis

Similar to the general American population, approximately 1/3rd of inflammatory bowel disease (IBD) patients are overweight and an additional 1/3rd are obese. Obesity in IBD patients is associated with increased difficulty in achieving remission, higher risk of disease relapse, higher hospitalization costs, and difficult surgical management. Adipose tissue is the largest endocrine organ producing and secreting cytokines, hormones, growth factors, and extracellular vesicles. Adipose tissue cellular composition, function, and secretion is strikingly altered during obesity. Alteration of adipose tissue‐derived EVs, including exosomes, during obesity is less understood. EVs carry molecular cargo that is actively taken up by other cell types and mediate phenotypic changes in recipient cells, resulting in intra‐organ communication. Since obesity is associated with abnormalities in gastrointestinal epithelial turnover, increased gut permeability, enhanced stemness, and decreased goblet cells, further studies are needed to elucidate the influence of obesity on pathomechanisms of underlying IBD. Here, we aim to investigate whether obese adipose tissue EVs alter acute disease or recovery in a model of induced colitis. As EV donor mice, C57BL/6 mice were fed from 4‐20 weeks of age a purified high fat diet (HFD) containing 45% kcal fat, a well‐established model of obesity, or purified matched diet (MD) containing 10% kcal fat. Visceral adipose tissue was cultured ex vivo, secreted EVs were isolated by ultracentrifugation, and concentration was determined by Nanoparticle Tracking Analysis. As EV recipient mice, a separate set of C57BL/6 mice were treated with 2.5% (wt/vol) dextran sodium sulfate (DSS) in drinking water for 6 days to induce acute colitis and were i.p. injected with MD EVs, HFD EVs, or vehicle (1xPBS) at a concentration of 10^8 EVs/g body weight every 2 days of DSS treatment. To test recovery from colitis, C57BL/6 mice were treated with 2.5% DSS for 6 days, were allowed to recover for an additional 6 days by removing DSS, and were treated with EVs every 2 days beginning on day 4 of DSS. Body weight and disease activity index (DAI) scores were measured daily. Colon was collected and swiss‐rolled for histology scoring (inflammation, extent, crypt damage, percent involvement) or RNA isolation for quantitative real‐time PCR analysis of Lcn2 as an indicator of inflammation. During acute DSS, body weights, DAI, colon length, and histology scoring did not change between mice injected with HFD EVs or MD EVs compared to vehicle. However, HFD EV treated mice exhibited delayed recovery from DSS colitis as evidenced by significantly higher DAI scores, colon shortening, and elevated levels of Lcn2 mRNA following recovery from DSS. These results suggest that EVs released by obese adipose tissue inhibit colitis recovery and provide insight on adipose‐to‐intestinal tissue communication elicited by EVs.

Intestinal inflammation alters the antigen-specific immune response to a skin commensal.

SUMMARYResident microbes in skin and gut predominantly impact local immune cell function during homeostasis. However, colitis-associated neutrophilic skin disorders suggest possible breakdown of this compartmentalization with disease. Using a model wherein neonatal skin colonization by Staphylococcus epidermidis facilitates generation of commensal-specific tolerance and CD4+ regulatory T cells (Tregs), we ask whether this response is perturbed by gut inflammation. Chemically induced colitis is accompanied by intestinal expansion of S. epidermidis and reduces gut-draining lymph node (dLN) commensal-specific Tregs. It also results in reduced commensal-specific Tregs in skin and skin-dLNs and increased skin neutrophils. Increased CD4+ circulation between gut and skin dLN suggests that the altered cutaneous response is initiated in the colon, and resistance to colitis-induced effects in Cd4creIl1r1fl/fl mice implicate interleukin (IL)-1 in mediating the altered commensal-specific response. These findings provide mechanistic insight into observed connections between inflammatory skin and intestinal diseases.

Enteric glial adenosine 2B receptor signaling mediates persistent epithelial barrier dysfunction following acute DSS colitis

Intestinal epithelial barrier function is compromised in inflammatory bowel disease and barrier dysfunction contributes to disease progression. Extracellular nucleotides/nucleosides generated in gut inflammation may regulate barrier function through actions on diverse cell types. Enteric glia modulate extracellular purinergic signaling and exert pathophysiological effects on mucosal permeability. These glia may regulate inflammation with paracrine responses, theoretically mediated via adenosine 2B receptor (A2BR) signaling. As the cell-specific roles of A2BRs in models of colitis and barrier dysfunction are unclear, we studied glial A2BRs in acute dextran sodium sulfate (DSS) colitis. We performed and validated conditional ablation of glial A2BRs in Sox10CreERT2+/−;Adora2bf/f mice. Overt intestinal disease activity indices in DSS-colitis were comparable between Sox10CreERT2+/–;Adora2bf/f mice and littermate controls. However, ablating glial A2BRs protected against barrier dysfunction following acute DSS-colitis. These benefits were associated with the normalization of tight junction protein expression and localization including claudin-1, claudin-8, and occludin. Glial A2BR signaling increased levels of proinflammatory mediators in the colon and cell-intrinsic regulation of genes including Csf3, Cxcl1, Cxcl10, and Il6. Our studies show that glial A2BR signaling exacerbates immune responses during DSS-colitis and that this adenosinergic cell-specific mechanism contributes to persistent gut epithelial barrier dysfunction.

P‐cadherin regulates intestinal epithelial repair, but is dispensable for colitis associated colon cancer development

Recurrent chronic mucosal inflammation, which is characteristics for inflammatory bowel diseases (IBD), triggers significant changes in the intestinal epithelial homeostasis. These changes include leakiness of the gut barrier, formation of mucosal wounds and, in most severe cases, oncogenic transformation of colonic epithelium resulting in colitis‐associated colon cancer (CAC). Altered structure and dynamics of epithelial junctions is a hallmark of intestinal inflammation, mediating epithelial barrier injury and repair. P‐cadherin (gene name: CDH3) is an important component of adherens junctions (AJ), which is poorly expressed in normal intestinal epithelium, but could be induced in inflamed and injured mucosa. The goal of this his study was to investigate the roles of P‐cadherin in regulating intestinal inflammation, mucosal repair and CAC.P‐cadherin expression was markedly induced in the colonic epithelium of human IBD patients and CAC tissues. Roles of P‐cadherin in intestinal inflammation and tumorigenesis in vivo were investigated using a mouse strain with total P‐cadherin knockout. Dextran sulfate sodium (DSS)‐induced colitis was utilized to study mucosal inflammation, whereas CAC was established using a classical azoxymetane (AOM)/DSS model. Severity of acute DSS colitis was not affected by P‐cadherin knockout, however, P‐cadherin null mice exhibited faster recovery after DSS withdrawal indicating accelerated repair of injured mucosa. No significant differences in the number and size of colonic tumors was observed in P‐cadherin null and control mice after AOM/DSS induced CAC. Consistently, CRISPR/Cas9‐mediated knockout of P‐cadherin in SK‐CO15 and HCA7 human colonic epithelial cell lines accelerated epithelial wound healing without affecting cell proliferation. The faster migration of P‐cadherin depleted cells was associated with diminished cell‐matrix adhesions and increased cell spreading. Loss of P‐cadherin resulted in activation of Src kinase and the pro‐migratory phenotype of P‐cadherin depleted cell was reversed by pharmacological inhibition of Src. Furthermore, accelerated epithelial wound healing caused by loss of P‐cadherin was prevented by Rac1 inhibition. Our findings highlight P‐cadherin as a negative regulator of intestinal epithelial would heling in vitro and mucosal repair in vivo. By contrast, this AJ protein appears to be dispensable for intestinal epithelial cell proliferation and CAC development.

P-Cadherin Regulates Intestinal Epithelial Cell Migration and Mucosal Repair, but Is Dispensable for Colitis Associated Colon Cancer.

Recurrent chronic mucosal inflammation, a characteristic of inflammatory bowel diseases (IBD), perturbs the intestinal epithelial homeostasis resulting in formation of mucosal wounds and, in most severe cases, leads to colitis-associated colon cancer (CAC). The altered structure of epithelial cell-cell adhesions is a hallmark of intestinal inflammation contributing to epithelial injury, repair, and tumorigenesis. P-cadherin is an important adhesion protein, poorly expressed in normal intestinal epithelial cells (IEC) but upregulated in inflamed and injured mucosa. The goal of this study was to investigate the roles of P-cadherin in regulating intestinal inflammation and CAC. P-cadherin expression was markedly induced in the colonic epithelium of human IBD patients and CAC tissues. The roles of P-cadherin were investigated in P-cadherin null mice using dextran sulfate sodium (DSS)-induced colitis and an azoxymethane (AOM)/DSS induced CAC. Although P-cadherin knockout did not affect the severity of acute DSS colitis, P-cadherin null mice exhibited faster recovery after colitis. No significant differences in the number of colonic tumors were observed in P-cadherin null and control mice. Consistently, the CRISPR/Cas9-mediated knockout of P-cadherin in human IEC accelerated epithelial wound healing without affecting cell proliferation. The accelerated migration of P-cadherin depleted IEC was driven by activation of Src kinases, Rac1 GTPase and myosin II motors and was accompanied by transcriptional reprogramming of the cells. Our findings highlight P-cadherin as a negative regulator of IEC motility in vitro and mucosal repair in vivo. In contrast, this protein is dispensable for IEC proliferation and CAC development.