Chronic Experimental Colitis Research Articles

Deficiency in epithelium RAD50 aggravates UC via IL-6-mediated JAK1/2-STAT3 signaling and promotes development of colitis-associated cancer in mice.

Ulcerative colitis (UC) is one of the most important risk factors for developing colitis-associated cancer (CAC). Persistent DNA damage increases CAC risk and has been observed in patients with UC. We aimed to identify the regulatory role of RAD50, a DNA double-strand breaks (DSBs) sensor, in UC progression to CAC. DSBs and RAD50 expression in IBD and CAC cell and mouse models were assessed. Mice with intestinal epithelial RAD50 deletion (RAD50IEC-KO) were used to examine the role of RAD50 in colitis and CAC. Along with the increased γ-H2AX expression in colitis and CAC models, RAD50 expression reduced in human IBD and CAC as well as in mouse models. Furthermore, RAD50IEC-KO sensitizes mice to dextran sulfate sodium (DSS)-induced acute and chronic experimental colitis. RNA-seq analyses revealed that RAD50 activated the cytokine-cytokine receptor response, which was amplified through the JAK-STAT pathway. RAD50 directly interacts with STAT3 and subsequently inhibits its phosphorylation, which may disrupt the IL-6-JAK1/2-STAT3-IL-6 feed-forward loop. Pharmacological STAT3 inhibition relieves colitis in RAD50IEC-KO mice. Severe DSBs, increased cell proliferation, and extended inflammatory response were identified in RAD50-deficienct cells, which promoted azoxymethane (AOM)-DSS-induced colon tumor development in RAD50IEC-KO mice. RAD50 exerts anti-IL-6-related inflammatory effects in colitis and suppresses CAC. Increasing RAD50 level in colon tissues may be promising for treating patients with UC and CAC.

Effect of a Flavonoid Combination of Apigenin and Epigallocatechin-3-Gallate on Alleviating Intestinal Inflammation in Experimental Colitis Models.

Inflammatory bowel disease (IBD) is an autoimmune disease that leads to severe bowel symptoms and complications. Currently, there is no effective treatment, and the exact cause of IBD remains unclear. In the last decades, numerous studies have confirmed that flavonoids can have a positive impact on the treatment of IBD. Therefore, this study investigated the protective effect of a flavonoid combination of apigenin and epigallocatechin-3-gallate (EGCG) on IBD. In vitro studies in which Caco-2 cell monolayers were incubated with different concentrations of flavonoids found that the flavonoid-treated group exhibited increased transepithelial electrical resistance (TEER) at high concentrations, indicating a protective effect on the barrier function of the intestinal epithelium. In vivo studies showed that flavonoids significantly attenuated inflammatory levels in both chronic and acute hapten-mediated experimental colitis models in a time- and dose-dependent manner. In addition, the activity of myeloperoxidase (MPO) and the level of proinflammatory cytokines in the colon tissue were significantly reduced. Interestingly, the levels of anti-inflammatory cytokines were also dramatically increased. Finally, flavonoids were found to positively modulate the composition of the gut microbiota in the colon. Therefore, a combination of flavonoids could be a promising therapeutic agent for the future adjunctive treatment of IBD.

IL-3 receptor signalling suppresses chronic intestinal inflammation by controlling mechanobiology and tissue egress of regulatory T cells

IL-3 has been reported to be involved in various inflammatory disorders, but its role in inflammatory bowel disease (IBD) has not been addressed so far. Here, we determined IL-3 expression...

Mutant LRRK2 exacerbates immune response and neurodegeneration in a chronic model of experimental colitis

The link between the gut and the brain in Parkinson’s disease (PD) pathogenesis is currently a subject of intense research. Indeed, gastrointestinal dysfunction is known as an early symptom in PD and inflammatory bowel disease (IBD) has recently been recognised as a risk factor for PD. The leucine-rich repeat kinase 2 (LRRK2) is a PD- and IBD-related protein with highest expression in immune cells. In this study, we provide evidence for a central role of LRRK2 in gut inflammation and PD. The presence of the gain-of-function G2019S mutation significantly increases the disease phenotype and inflammatory response in a mouse model of experimental colitis based on chronic dextran sulphate sodium (DSS) administration. Bone marrow transplantation of wild-type cells into G2019S knock-in mice fully rescued this exacerbated response, proving the key role of mutant LRRK2 in immune cells in this experimental colitis model. Furthermore, partial pharmacological inhibition of LRRK2 kinase activity also reduced the colitis phenotype and inflammation. Moreover, chronic experimental colitis also induced neuroinflammation and infiltration of peripheral immune cells into the brain of G2019S knock-in mice. Finally, combination of experimental colitis with overexpression of α-synuclein in the substantia nigra aggravated motor deficits and dopaminergic neurodegeneration in G2019S knock-in mice. Taken together, our results link LRRK2 with the immune response in colitis and provide evidence that gut inflammation can impact brain homeostasis and contribute to neurodegeneration in PD.

HIF-1α-Overexpressing Mesenchymal Stem Cells Attenuate Colitis by Regulating M1-like Macrophages Polarization toward M2-like Macrophages

A modified mesenchymal stem cell (MSC) transplantation is a highly effective and precise treatment for inflammatory bowel disease (IBD), with a significant curative effect. Thus, we aim to examine the efficacy of hypoxia-inducible factor (HIF)-1α-overexpressing MSC (HIF-MSC) transplantation in experimental colitis and investigate the immunity regulation mechanisms of HIF-MSC through macrophages. A chronic experimental colitis mouse model was established using 2,4,6-trinitrobenzene sulfonic acid. HIF-MSC transplantation significantly attenuated colitis in weight loss rate, disease activity index (DAI), colon length, and pathology score and effectively rebuilt the local and systemic immune balance. Macrophage depletion significantly impaired the benefits of HIF-MSCs on mice with colitis. Immunofluorescence analysis revealed that HIF-MSCs significantly decreased the number of M1-like macrophages and increased the number of M2-like macrophages in colon tissues. In vitro, co-culturing with HIF-MSCs significantly decreased the expression of pro-inflammatory factors, C-C chemokine receptor 7 (CCR-7), and inducible nitric oxide synthase (INOS) and increased the expression of anti-inflammatory factors and arginase I (Arg-1) in induced M1-like macrophages. Flow cytometry revealed that co-culturing with HIF-MSCs led to a decrease in the proportions of M1-like macrophages and an increase in that of M2-like macrophages. HIF-MSCs treatment notably upregulated the expression of downstream molecular targets of phosphatidylinositol 3-kinase-γ (PI3K-γ), including HIF-1α and p-AKT/AKT in the colon tissue. A selected PI3K-γ inhibitor, IPI549, attenuated these effects, as well as the effect on M2-like macrophage polarization and inflammatory cytokines in colitis mice. In vitro, HIF-MSCs notably upregulated the expression of C/EBPβ and AKT1/AKT2, and PI3K-γ inhibition blocked this effect. Modified MSCs stably overexpressed HIF-1α, which effectively regulated macrophage polarization through PI3K-γ. HIF-MSC transplantation may be a potentially effective precision therapy for IBD.

Anthocyanin extract from black rice attenuates chronic inflammation in DSS-induced colitis mouse model by modulating the gut microbiota

AbstractThere is substantial evidence for the probiotic activity of anthocyanins, but the relationship between anthocyanins involved in the regulation of microbiota and intestinal inflammation has not been fully elucidated. The aim of this study was to investigate the regulatory effects of black rice anthocyanin extract (BRAE) on intestinal microbiota imbalance in mice with dextran sulfate sodium (DSS)-induced chronic colitis. DSS was added into drinking water to induce a mouse model of chronic experimental colitis, and BRAE was given by gavage (200 mg/kg/day) for 4 weeks. Body weight, fecal viscosity, and hematochezia were monitored during administration. After mice were sacrificed, the serum concentrations of TNF-α and IL-6 were detected by enzyme-linked immunosorbent assay, and the composition of intestinal flora was analyzed by 16S rDNA sequencing. The results showed that BRAE significantly suppressed DSS-induced colonic inflammatory phenotypes and maintained colon length in mice. In addition, BRAE reduced intestinal permeability and improved intestinal barrier dysfunction in mice with colitis. Gut microbiota analysis showed that BRAE significantly improved the imbalance of intestinal microecological diversity caused by DSS, inhibited the increase in the relative abundance of inflammatory bacteria, and promoted the abundance of anti-inflammatory probiotics includingAkkermansiaspp.

P009 IL-3 receptor signalling suppresses chronic intestinal inflammation by controlling mechanobiology and tissue egress of regulatory T cells

Abstract Background The pathogenesis of inflammatory bowel diseases (IBD) such as Crohn’s disease (CD) and ulcerative colitis (UC) is still incompletely understood. However, despite having been described back in the 1980s and reported to be involved in chronic inflammatory arthritis, the role of interleukin 3 (IL-3) signaling via the IL-3 receptor (IL-3R) in the development and perpetuation of chronic intestinal inflammation remains largely unexplored. In this study, we therefore aimed to explore the role of IL-3 signaling via IL-3R in experimental colitis as well as human IBD. Methods We analysed IL-3 expression in lamina propria mononuclear cells (LPMCs) from patients with IBD and from mice with experimental colitis. We compared the development of T cell transfer colitis in Rag1-/- mice after transfer of Il3r-/- and Il3r+/+ naïve T cells and investigated the underlying mechanisms by immunofluorescence and functional cell trafficking assays. The mechanical properties of Il3r-/- and Il3r+/+ T cells were determined by real-time deformability cytometry (RT-DC) and atomic force microscopy (AFM) and cytoskeleton structure was analysed by scanning electron microscopy (SEM) and fluorescence recovery after photobleaching (FRAP). Results The expression of IL-3 and IL3+ T cells were increased in the gut of patients with IBD and IL-3 expression was associated to shorter flare-free survival. In vivo, experimental chronic colitis upon T cell transfer was exacerbated in the absence of IL-3 or IL-3R signalling. This was attributable to IL-3-induced changes in kinase signalling and actin cytoskeleton structure, resulting in increased mechanical deformability and enhanced egress of regulatory T (Treg) cells from the inflamed colon mucosa. Similarly, IL-3 controlled mechanobiology in human Treg cells. (A) IL3 mRNA expression in colon tissue from patients.(B) Flare-free survival of IBD patients.(C) Colitis in Rag1–/– mice after transfer of naïve CD4+ T cells from Il3r+/+ and Il3r-/- mice. Mini-endoscopy (left) and IVIS (right).(D) RT-DC plot (left) and quantification (right) of thymic lymphocytes from Il3r-/- and Il3r+/+ mice.(E) Lightsheet microscopy (left) and quantification of TReg index (right, TReg fraction in Ozanimod/DATK32 per fraction in placebo) in mLNs from Rag1-/- mice with transfer colitis induced by Il3r-/- or Il3r+/+ T cells. Conclusion We uncover a crucial role of IL-3R signalling in regulating TReg mechanobiology and tissue egress. Together, our data demonstrate a central – probably counter-regulatory – role for IL-3 receptor signalling in Treg cells in the pathogenesis of murine and human chronic intestinal inflammation and therefore suggest that IL-3 might be a novel target for future therapeutic approaches in IBD.

Wumei Wan attenuates angiogenesis and inflammation by modulating RAGE signaling pathway in IBD: Network pharmacology analysis and experimental evidence

BackgroundWumei Wan (WMW) has been used to address digestive disorder for centuries in traditional Chinese medicine. Previous studies have demonstrated its anti-colitis efficacy, but the underlying mechanism of its action remains to be further clarified. PurposeTo investigate the underlying mechanisms of WMW in the treatment of chronic ulcerative colitis (UC) through network pharmacology and experimental validation. MethodsTraditional Chinese Medicine Systems Pharmacology (TCMSP) platform were used to identify the ingredients and potential targets of WMW. The microarray gene data GSE75214 datasets from GEO database was used to define UC-associated targets. Cytoscape3.7.2 was employed to construct the protein-protein interaction (PPI) network and compounds-disease targets network. GO enrichment analysis and KEGG pathway analysis were performed by R software for functional annotation. UPLC-TOF-MS/MS method was used to quantitatively analyze the active ingredients of WMW. For experimental validation, three cycles of 2% dextran sulfate sodium salt (DSS) were used to construct chronic colitis model. The hub targets and signal pathway were detected by qPCR, ELISA, western blotting , immunohistochemical and immunofluorescence. ResultsThrough network analysis, 104 active ingredients were obtained from WMW, and 47 of these ingredients had potential targets for UC. A total of 41 potential targets of WMW and 13 hub targets were identified. KEGG analysis showed that WMW involved in advanced glycation end products-receptor of advanced glycation end products (AGE-RAGE) signaling pathway. Taxifolin, rutaecarpine, kaempferol, quercetin, and luteolin of WMW were the more highly predictive components related to the AGE-RAGE signaling pathway. In vivo validation, WMW improved DSS-induced colitis, reduced the expression of inflammatory cytokines and chemokines. Notably, it significantly decreased the mRNA expression of Spp1, Serpine1, Mmp2, Mmp9, Ptgs2, Nos2, Kdr and Icam1, which were associated with angiogenesis. In addition, we confirmed WMW inhibited RAGE expression and diminished DSS-induced epithelial barrier alterations ConclusionOur results initially demonstrated the effective components and the strong anti-angiogenic activity of WMW in experimental chronic colitis. Sufficient evidence of the satisfactory anti-colitis action of WMW was verified in this study, suggesting its potential as a quite prospective agent for the therapy of UC.

Nattokinase enhances the preventive effects of Escherichia coliNissle 1917 on dextran sulfate sodium-induced colitis in mice.

Nattokinase with excellent anti-thrombotic, anti-inflammatory, anti-tumor, and anti-hypertension properties has been used in the development of several healthcare products in many countries. The probiotic Escherichia coli Nissle 1917 (EcN) with anti-inflammatory effect is commonly used to treat inflammatory bowel disease. To determine whether nattokinase could enhance the therapeutic efficacy of EcN in colitis, a recombinant E. coli Nissle 1917 strain (EcNnatto) with nattokinase-expressing ability was successfully constructed, and the protective effect of the engineered strain on mice with experimental chronic colitis was investigated. Although both EcN and EcNnatto strains substantially alleviated the clinical symptoms and pathological abnormalities in colitis mice by regulating gut flora and maintaining intestinal barrier function, the EcNnatto strain was found to perform better than the control strain, based on a further increase in colon length and a downregulation in pro-inflammatory cytokines (IL-6 and TNF-α). Nattokinase expressed in EcN attenuated DSS-induced epithelial damage and restored the mucosal integrity by upregulating the levels of tight junction proteins, including ZO-1 and occludin. The expression level of Lgr5, a marker of intestinal stem cells, was also increased. Moreover, constitutively expressed nattokinase in EcN reversed the gut microbial richness and diversity in colitis mice. Based on our findings, nattokinase could strengthen the capacity of EcN to treat intestinal inflammation.

Anti-Inflammatory Effect of Topiramate in a Chronic Model of TNBS-Induced Colitis.

Inflammatory bowel disease (IBD) is characterized by a chronic and relapsing inflammatory response in the gastrointestinal tract, resulting in severe symptoms such as abdominal pain, vomiting, diarrhea, bloody stools, and weight loss. Currently, there is no cure, and the pharmacological treatment includes drugs that induce and keep the patient in remission, not reversing the underlying pathogenic mechanism. These therapies, in the long term, may cause various side effects and complications, which has increased the need to investigate new, more effective, and safer pharmacological approaches. In preclinical studies, topiramate has demonstrated a potential anti-inflammatory effect by inhibiting the production of several pro-inflammatory cytokines. This study aimed to investigate the effect of topiramate in a chronic TNBS-induced colitis model in rodents. Experimental colitis was induced by four intrarectal administrations of 1% TNBS in female CD-1 mice. Topiramate 10 and 20 mg were administered intraperitoneally for 14 days. Several parameters were evaluated, such as bodyweight, alkaline phosphatase (ALP), fecal hemoglobin, fecal calprotectin, tumor necrosis factor (TNF)-α, and interleukin (IL)-10. Topiramate reduces TNBS-induced colonic damage in a model of chronic experimental colitis and normalizes the stool consistency and anus appearance. Additionally, topiramate significantly reduced the concentration of ALP, fecal hemoglobin, fecal calprotectin, TNF-α, and IL-10, demonstrating it to be a promising pharmacological approach for the treatment of IBD in the future.

Recovery of Ischemic Limb and Femoral Artery Endothelial Function Are Preserved in Mice with Dextran Sodium Sulfate-Induced Chronic Colitis

Simple SummaryThe present study examines the effect of experimental inflammatory bowel disease on femoral artery endothelial function and limb ischemia recovery in female mice using a chronic colitis model induced by dextran sodium sulfate exposure. As expected, plasma levels of proinflammatory cytokines, including interleukin-6, interleukin-17, tumor necrosis factor alpha, and chemokine ligand 1, were significantly increased in the chronic colitis model. However, ROS levels in the ischemic muscle tissues were not significantly increased in mice with colitis as compared to controls. There were no significant changes in endothelium-dependent or -independent vasodilation of femoral artery between the colitis model and the control. Recovery of function and blood flow of the ischemic limb and capillary density in the ischemic muscle were preserved in the colitis model as compared with the control.Inflammatory bowel disease (IBD) produces significant systemic inflammation and increases the risk of endothelial dysfunction and peripheral artery disease. Our recent study demonstrated that abdominal aortic endothelial cell function was impaired selectively in female mice with chronic colitis. This study aimed to test the hypothesis that experimental colitis leads to femoral artery endothelial cell dysfunction and impairs limb ischemia recovery in female mice. An experimental chronic colitis model was created in female C57BL/6 mice with dextran sodium sulfate (DSS) treatment. Unilateral hind limb ischemia was produced by femoral artery ligation. Limb blood perfusion, vascular density, tissue ROS levels, and plasma levels of proinflammatory cytokines were assessed. Femoral artery endothelium-dependent and -independent vasodilation of the contralateral limb were evaluated ex vivo using acetylcholine and nitroglycerin, respectively. As expected, the plasma levels of proinflammatory cytokines, including tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, and IL-17, were significantly increased in the DSS-induced colitis model. However, ROS levels in the ischemic muscle tissues were not significantly increased in colitis model as compared to the controls. There were no significant changes in endothelium-dependent or -independent vasodilation of the femoral artery between colitis model and the control. Recovery of function and blood flow in the ischemic limb and capillary density in the ischemic gastrocnemius muscle were preserved in the colitis model as compared with the control. The data demonstrated that DSS-induced chronic colitis had no significant impact on femoral artery endothelial function or ischemic limb recovery in female mice.

Dietary Oyster (Crassostrea gigas) Extract Ameliorates Dextran Sulfate Sodium-Induced Chronic Experimental Colitis by Improving the Composition of Gut Microbiota in Mice.

Previously, we have reported that the intake of oyster extract (OE), prepared from Pacific oysters (Crassostrea gigas), can attenuate symptoms of dextran sulfate sodium (DSS)-induced acute experimental colitis in mice. Herein, we aimed to evaluate whether OE intake ameliorates chronic experimental colitis induced by repeated DSS administration in mice. Male C57BL/6J (4-week-old) mice were fed either the standard diet AIN93G (control diet) or the control diet containing 5.0% (w/w) OE (OE diet). After 21 days of diet feeding, chronic experimental colitis was induced by three cycles of 2.0% (w/w) DSS solution administration (5 days), followed by distilled water (5 days). Mice fed OE alleviated the shortened colonic length, increased the relative weight of the spleen, colonic histopathological score (regeneration), and blood in the stool score compared with mice fed control diet. A tendency to improve the α-diversity of fecal microbiota, which was exacerbated by colitis, was observed in mice fed OE. Correlation analysis suggested that the anti-colitis effect of OE intake could be related to the valeric acid content and relative abundances of Ruminococcus and Enterococcus in the feces. In conclusion, OE could ameliorate DSS-induced chronic experimental colitis by improving the gut environment, including the microbiota community and SCFA composition.

Mitochondrial complex I dysfunction alters the balance of soluble and membrane-bound TNF during chronic experimental colitis

Inflammatory bowel disease (IBD) is a complex, chronic, relapsing and heterogeneous disease induced by environmental, genomic, microbial and immunological factors. MCJ is a mitochondrial protein that regulates the metabolic status of macrophages and their response to translocated bacteria. Previously, an acute murine model of DSS-induced colitis showed increased disease severity due to MCJ deficiency. Unexpectedly, we now show that MCJ-deficient mice have augmented tumor necrosis factor α converting enzyme (TACE) activity in the context of chronic inflammation. This adaptative change likely affects the balance between soluble and transmembrane TNF and supports the association of the soluble form and a milder phenotype. Interestingly, the general shifts in microbial composition previously observed during acute inflammation were absent in the chronic model of inflammation in MCJ-deficient mice. However, the lack of the mitochondrial protein resulted in increased alpha diversity and the reduction in critical microbial members associated with inflammation, such as Ruminococcus gnavus, which could be associated with TACE activity. These results provide evidence of the dynamic metabolic adaptation of the colon tissue to chronic inflammatory changes mediated by the control of mitochondrial function.

Plum Prevents Intestinal and Hepatic Inflammation in the Acute and Chronic Models of Dextran Sulfate Sodium-Induced Mouse Colitis.

Inflammatory bowel disease (IBD), including ulcerative colitis (UC), is a chronic recurrent inflammatory disease of the digestive tract and increases the risk of colon cancer. This study evaluates the effects of dietary intervention with freeze-dried plum (FDP), a natural antioxidant and anti-inflammatory fruit with no toxicity on dextran sulfate sodium (DSS)-induced acute and chronic experimental colitis in a mouse model and studies the molecular mechanisms of protection through the gut-liver axis. The results show that FDP decreases the levels of inflammatory mediators, which is a nitrative stress biomarker in both acute and chronic models. FDP markedly reduces DSS-induced injury to the colonic epithelium in both acute and chronic models. In addition, FDP significantly decreases the levels of pro-oxidant markers such as CYP2E1, iNOS, and nitrated proteins (detected by anti-3-NT antibody) in DSS-induced acute and chronic colonic injury models. Furthermore, FDP markedly reduces markers of liver injury such as serum ALT/AST, antioxidant markers, and inflammatory mediators in DSS-induced acute and chronic colonic injury. These results demonstrate that the FDP exhibits a protective effect on DSS-induced acute and chronic colonic and liver injury through the gut-liver axis via antioxidant and anti-inflammatory properties.

The protective role of Chitooligosaccharides against chronic ulcerative colitis induced by dextran sulfate sodium in mice

• Protective effect of COS on the DSS-induced chronic experimental UC development. • Anti-inflammatory and anti-apoptotic activities of COS in chronic UC mice. • COS promoted the proliferation of crypt epithelial cells in chronic UC mice. • COS modulated gut microbiota in chronic UC mice. • Possible involvement of TLR4 signal pathway in COS-mediated protection in chronic UC. • Possible involvement of colonic Reg3g in COS-mediated protection in chronic UC. Chitooligosaccharides(COS) as potential functional food has been paid great attention because of their outstanding biological activities. Here, we found COS (250 and 500 mg/kg) protected against development of dextran sodium sulfate(DSS)- induced chronic experimental ulcerative colitis(UC) in mice. DSS-elevated serum and colonic tumor necrosis factor(TNF)-α, interleukin(IL)-1β and IL-6 levels were significantly supressed. TUNEL + apoptoic cells and Cleaved Caspase-9 expression were downregulated, Ki-67 + proliferative cells in colonic crypts and Bcl-2/Bax ratio were upregulated in COS-treated colons compared to DSS controls. COS enhanced gut microbiota diversity and restored community structure in chronic UC mice. Colonic expression of TLR4, NF-κB, STAT3 and pSTAT3 was significantly decreased, but that of regenerating islet derived 3 gamma(Reg3g) was increased by COS. Overall, COS represents a treatment alternative in chronic UC management via ameliorating inflammation, promoting mucosal repair and modulating gut microbiota. Inhibition of TLR4 signal and induction of colonic Reg3g might be involved in molecular mechanisms.

Asperuloside suppressing oxidative stress and inflammation in DSS-induced chronic colitis and RAW 264.7 macrophages via Nrf2/HO-1 and NF-κB pathways

BackgroundInflammatory bowel diseases (IBDs), which mainly include Crohn's disease (CD) and ulcerative colitis (UC), are chronic idiopathic inflammatory disease of the gastrointestinal tract for which effective pharmacological treatments are lacking or options are very limited. PurposeHere, we aim to investigate the therapeutic effects of an iridoid glycoside, asperuloside (ASP) on mice experimental chronic colitis induced by dextran sulfate sodium (DSS) and further explore underlying mechanisms in vitro and in vivo. MethodsLPS-treated RAW 264.7 cells showed inflammation and were assessed for various physiological, morphological and biochemical parameters in the absence or presence of ASP. Chronic colitis was induced by 2% DSS in mice, which were used as an animal model to explore the pharmacodynamics of ASP. We detected p65 and Nrf2 pathway proteins via Western blot and RT-PCR analysis, assessed the cytokines TNF-α and IL-6 via ELISA, tested p65 and Nrf2 nuclear translocation via fluorescence. In addition, the docking affinity of ASP and p65 or Nrf2 proteins in the MOE 2015 software. ResultsWe found that ASP attenuated weight loss, disease activity index (DAI) and colonic pathological damage in colitis mice and restored the expressions of inflammatory cytokines in the colon. In addition, ASP restored antioxidant capacity in DSS-induced chronic colitis mice and lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Furthermore, ASP suppressed oxidative stress through increasing Nrf2, HO-1 and NQO-1 proteins expressions, and down-regulated nuclear levels of p65 to inhibit DSS-induced colonic oxidative stress and inflammation. Validation of the molecular docking results also indicated that ASP interacts with Nrf2 or p65 proteins. In summary, ASP improved DSS-induced chronic colitis by alleviating inflammation and oxidative stress, activating Nrf2/HO-1 signaling and limiting NF-κB signaling pathway, which may be an effective candidate for the treatment of IBD.

Si-Ni-San ameliorates chronic colitis by modulating type I interferons-mediated inflammation

BackgroundUlcerative colitis (UC) is a chronic relapsing inflammatory disease that markedly elevates the risk of colon cancers and results in disability. The disrupted immune homeostasis has been recognized as a predominant player in the pathogenesis of UC. However, the overall remission rate of current therapies based on immunoregulation is still unsatisfactory. Si-Ni-San (SNS) has been found effective in relieving UC through thousands of years of clinical practice, yet the specific mechanisms of the protective effect of SNS were not fully elucidated. PurposeWe aim to investigate the therapeutic effects of SNS against the development of chronic colitis and the underlying mechanisms. MethodsWe established a DSS-induced chronic experimental colitis mouse model to evaluate the effect of SNS. RNA-sequencing, bioinformatic analysis, and in vitro studies were performed to investigate the underlying mechanisms. ResultsOur data demonstrated that SNS significantly ameliorated chronic experimental colitis via inhibiting the expression of genes associated with inflammatory responses. Interestingly, SNS significantly suppressed DSS-induced type I interferon (IFN) responses instead of directly downregulating the production of pro-inflammatory cytokines, such as Il-6. In vitro study further found that SNS selectively inhibited STING and RIG-I pathway-induced type I IFN responses by modulating TBK1- and IRF3-dependent signaling transduction. SNS also suppressed the expression of IFN-stimulated genes by directly inhibiting STAT1 and STAT2 activation. ConclusionOur study not only provides novel insights into the pathogenic role of type I IFN responses in colitis but also suggested that SNS or bioactive compounds derived from SNS may serve as novel therapeutic strategies for the treatment of UC via interfering type I IFN-mediated inflammation.

Electroacupuncture preserves intestinal barrier integrity through modulating the gut microbiota in DSS-induced chronic colitis

AimsElectroacupuncture (EA) at ST36 has been verified to ameliorate experimental acute colitis. However, the effect of EA on chronic colitis and its mechanism has not yet been explored. This study aimed to assess the protective effect of EA against chronic colitis and the related mechanisms. Main methodsChronic colitis was induced by dextran sulfate sodium (DSS) in C57BL/6 mice, and EA was applied throughout the entire experiment. Colonic inflammation and intestinal barrier integrity were evaluated. Alterations in the gut microbiota were analyzed by 16S rRNA gene sequencing. The fecal microbiota transplantation (FMT) experiment was used to further confirm the effect of the gut microbiota on the barrier protective effect of EA. The potential molecular mechanisms were explored by western blotting. Key findings(1) EA lowered the disease activity index (DAI) and histological scores, decreased the levels of TNFα, IL1β, IL6 and iNOS, and increased the IL10 level in DSS-induced chronic colitis. (2) EA upregulated the protein expression of ZO-1, Occludin, E-Cadherin and mucin2 (MUC2), reduced the apoptosis and proliferation of intestinal epithelial cells (IECs) and intestinal permeability. (3) EA enhanced the gut microbiota diversity and restored the community structure. (4) Both the low-frequency EA (LEA) FMT and high-frequency EA (HEA) FMT maintained the intestinal barrier integrity. (5) EA promoted activation of the mitogen activated protein kinase (MAPK) signaling pathway. SignificanceEA can relieve chronic experimental colitis, and this effect may depend on activation of the MAPK signaling pathway through modulation of the gut microbiota to preserve the intestinal barrier.

Development and Characterization of a New Endoscopic Drug-Eluting Platform With Proven Efficacy in Acute and Chronic Experimental Colitis.

Background and Aims: Mucosal lesions refractory to biological treatments represent unmet needs in patients with inflammatory bowel disease (IBD) that require new treatment modalities. We developed and characterized a new endoscopic drug-eluting hydrogel (CoverGel) with proven efficacy in acute and chronic experimental colitis (EC) in rats.Methods: CoverGel was developed based on appropriate rheological, drug release, gelation, structural, and degradation property capacities to allow endoscopic application. Experimental colitis (EC) was induced by TNBS application in rats. In acute EC 40, rats were randomized in five groups (eight each): Sham, Control, CoverGel, CoverGel + Infliximab (IFX) and CoverGel + Vedolizumab (VDZ). In chronic EC, 12 rats were randomized in two groups (six each): IFX s.c. and CoverGel + IFX. Endoscopic, histological, and blood test were performed during follow-up to evaluate clinical success. Antibodies to IFX (ATIs) were evaluated in chronic EC animal study.Results: CoverGel is a biocompatible and bioadhesive reverse thermosensitive gelation hydrogel with a macroporous structure and drug release capacity. In acute EC animals treated with CoverGel + IFX or CoverGel + VDZ showed significantly clinical success (weight recovery, mucosal restoration, and bacterial translocation) as compared with controls and animals without a bioactive drug. In a chronic EC animal study, clinical efficacy was comparable in both groups. Levels of ATIs were significantly lower in animals treated with CoverGel + IFX vs. IFX s.c. (0.90 ± 0.06 μg/mL-c vs. 1.97 ± 0.66 μg/mL-c, p = 0.0025).Conclusions: CoverGel is an endoscopic vehicle to locally deliver biological drugs with proven efficacy in acute and chronic EC in rats and induce less immunogenicity reaction.

TL1A primed dendritic cells activation exacerbated chronic murine colitis

AimsTumor necrosis factor-like ligand 1A (TL1A) has been proved to activate adaptive immunity in inflammatory bowel disease (IBD). However, its role in the regulation of intestinal dendritic cells (DCs) has not been fully characterized. This study aims to investigate the modulation of TL1A in DCs activation in murine colitis. Materials and methodsMyeloid TL1A-Transgenic C57BL/6 mice and wild-type (WT) mice were administrated with dextran sulfate sodium (DSS) to explore the effects of TL1A in murine colitis. Bone marrow-derived DCs (BMDCs) were isolated to detect the ability of antigen phagocytosis and presentation. The expression of nuclear factor-κB (NF-κB) pathway and chemokines receptors (CCRs) was assessed by real-time PCR and Western blot. Key findingsMyeloid cells with constitutive TL1A expression developed worsened murine colitis with exacerbated TH1/TH17 cytokine responses. Intestinal DCs from TL1A transgenic mice expressed high levels of costimulatory molecules (CD80 and CD86) with increased pro-inflammatory cytokines of IL-1β, TNF-α and IL-12/23 p40. Mechanistic studies showed that TL1A enhanced the phagocytotic ability of BMDCs. Moreover, TL1A enhanced the capacity of antigen process and presentation in BMDCs. Besides, TL1A induced the phosphorylation of NF-κB(p65) and IκBα. Meanwhile, higher expression of CCR2, CCR5, CCR7, and CX3CR1 was observed both in vivo and in vitro. SignificanceTL1A exacerbated DSS-induced chronic experimental colitis, probably through activation and migration of dendritic cells, and therefore increasing the secretion of pro-inflammatory cytokines.