Supramolecular Peptide Self-Assemblies Facilitate Oral Immunization

Oral immunization is a promising strategy for preventing and treating gastrointestinal (GI) infections and diseases, as it allows for direct access to the disease site. To elicit immune responses within the GI tract, however, there are many obstacles that oral vaccines must surmount, including proteolytic degradation and thick mucus barriers. Here, we employed a modular self-assembling peptide nanofiber platform to facilitate oral immunization against both peptide and small molecule epitopes. Synthesizing nanofibers with d-amino acids rendered them resistant to proteases in vitro, whereas l-amino acid nanofibers were rapidly degraded. Additionally, the inclusion of peptide sequences rich in proline, alanine, and serine (PAS), increased nanofiber muco-penetration, and accelerated nanofiber transport through the GI tract. Oral immunization with PASylated nanofibers and mucosal adjuvant generated local and systemic immune responses to a peptide epitope but only for l-amino acid nanofibers. Further, we were able to apply this design to also enable oral immunization against a small molecule epitope and illustrated the therapeutic and prophylactic effectiveness of these immunizations in mouse models of colitis. These findings demonstrate that supramolecular peptide self-assemblies have promise as oral vaccines and immunotherapies.

Sirt2 inhibition improves gut epithelial barrier integrity and protects mice from colitis

Sirt2 is a nicotinamide adenine dinucleotide (NAD+)-dependent protein lysine deacylase that can remove both acetyl group and long-chain fatty acyl groups from lysine residues of many proteins. It was reported to affect inflammatory bowel disease (IBD) symptoms in a mouse model. However, conflicting roles were reported, with genetic knockout aggravating while pharmacological inhibition alleviating IBD symptoms. These seemingly conflicting reports cause confusion and deter further efforts in developing Sirt2 inhibitors as a potential treatment strategy for IBD. We investigated these conflicting reports and elucidated the role of Sirt2 in the mouse model of IBD. We essentially replicated these conflicting results and confirmed that Sirt2 inhibitors' protective effect is not through off-targets as two very different Sirt2 inhibitors (TM and AGK2) showed similar protection in the IBD mouse model. We believe that the differential effects of inhibitors and knockout are due to the fact that the Sirt2 inhibitors only inhibit some but not all the activities of Sirt2. This hypothesis is confirmed by the observation that a PROTAC degrader of Sirt2 did not protect mice in the IBD model, similar to Sirt2 knockout. Our study provides an interesting example where genetic knockout and pharmacological inhibition do not align and emphasizes the importance of developing substrate-dependent inhibitors. Importantly, we showed that the effect of Sirt2 inhibition in IBD is through regulating the gut epithelium barrier by inhibiting Arf6-mediated endocytosis of E-cadherin, a protein important for the intestinal epithelial integrity. This mechanistic understanding further supports Sirt2 as a promising therapeutic target for treating IBD.

A human milk oligosaccharide prevents intestinal inflammation in adulthood via modulating gut microbial metabolism

Observational evidence suggests that human milk oligosaccharides (HMOs) promote the growth of commensal bacteria in early life and adulthood. However, the mechanisms by which HMOs benefit health through modulation of gut microbial homeostasis remain largely unknown. 2'-fucosyllactose (2'-FL) is the most abundant oligosaccharide in human milk and contributes to the essential health benefits associated with human milk consumption. Here, we investigated how 2'-FL prevents colitis in adulthood through its effects on the gut microbial community. We found that the gut microbiota from adult mice that consumed 2'-FL exhibited an increase in abundance of several health-associated genera, including Bifidobacterium and Lactobacillus. The 2'-FL-modulated gut microbial community exerted preventive effects on colitis in adult mice. By using Bifidobacterium infantis as a 2'-FL-consuming bacterial model, exploratory metabolomics revealed novel 2'-FL-enriched secretory metabolites by Bifidobacterium infantis, including pantothenol. Importantly, pantothenate significantly protected the intestinal barrier against oxidative stress and mitigated colitis in adult mice. Furthermore, microbial metabolic pathway analysis identified 26 dysregulated metabolic pathways in fecal microbiota from patients with ulcerative colitis, which were significantly regulated by 2'-FL treatment in adult mice, indicating that 2'-FL has the potential to rectify dysregulated microbial metabolism in colitis. These findings support the contribution of the 2'-FL-shaped gut microbial community and bacterial metabolite production to the protection of intestinal integrity and prevention of intestinal inflammation in adulthood.IMPORTANCEAt present, neither basic research nor clinical studies have revealed the exact biological functions or mechanisms of action of individual oligosaccharides during development or in adulthood. Thus, it remains largely unknown whether human milk oligosaccharides could serve as effective therapeutics for gastrointestinal-related diseases. Results from the present study uncover 2'-FL-driven alterations in bacterial metabolism and identify novel B. infantis-secreted metabolites following the consumption of 2'-FL, including pantothenol. This work further demonstrates a previously unrecognized role of pantothenate in significantly protecting the intestinal barrier against oxidative stress and mitigating colitis in adult mice. Remarkably, 2'-FL-enhanced bacterial metabolic pathways are found to be dysregulated in the fecal microbiota of ulcerative colitis patients. These novel metabolic pathways underlying the bioactivities of 2'-FL may lay a foundation for applying individual oligosaccharides for prophylactic intervention for diseases associated with impaired intestinal homeostasis.

The Lactobacillus plantarum P-8 Probiotic Microcapsule Prevents DSS-Induced Colitis through Improving Intestinal Integrity and Reducing Colonic Inflammation in Mice

Probiotics, recognized as beneficial and active microorganisms, often face challenges in maintaining their functionality under harsh conditions such as exposure to stomach acid and bile salts. In this investigation, we developed probiotic microcapsules and assessed their protective effects and underlying mechanisms in a murine model of dextran sulfate sodium (DSS)-induced colitis using male C57BL/6J mice. The administration of the probiotic microcapsules significantly mitigated body weight loss, prevented colon length shortening, decreased the disease activity index scores, and reduced histopathological scores in mice with DSS-induced colitis. Concurrently, the microencapsulated probiotics preserved intestinal barrier integrity by upregulating the expressions of tight junction proteins ZO-1 and occludin, as well as the mucus layer component MUC-2. Moreover, the treatment with probiotic microcapsules suppressed the activation of the NLRP3 inflammasome signaling pathway in the context of DSS-induced colitis. In conclusion, these findings support the utilization of probiotic microcapsules as a potential functional food ingredient to maintain the permeability of the intestinal barrier and alleviate colonic inflammation in UC.

A Pro-Regenerative Supramolecular Prodrug Protects Against and Repairs Colon Damage in Experimental Colitis

Structural repair of the intestinal epithelium is strongly correlated with disease remission in inflammatory bowel disease (IBD); however, ulcer healing is not addressed by existing therapies. To address this need, this study reports the use of a small molecule prolyl hydroxylase (PHD) inhibitor (DPCA) to upregulate hypoxia-inducible factor one-alpha (HIF-1α) and induce mammalian regeneration. Sustained delivery of DPCA is achieved through subcutaneous injections of a supramolecular hydrogel, formed through the self-assembly of PEG-DPCA conjugates. Pre-treatment of mice with PEG-DPCA is shown to protect mice from epithelial erosion and symptoms of dextran sodium sulfate (DSS)-induced colitis. Surprisingly, a single subcutaneous dose of PEG-DPCA, administered after disease onset, leads to accelerated weight gain and complete restoration of healthy tissue architecture in colitic mice. Rapid DPCA-induced restoration of the intestinal barrier is likely orchestrated by increased expression of HIF-1α and associated targets leading to an epithelial-to-mesenchymal transition. Further investigation of DPCA as a potential adjunctive or stand-alone restorative treatment to combat active IBD is warranted.

Pretreatment with an antibiotics cocktail enhances the protective effect of probiotics by regulating SCFA metabolism and Th1/Th2/Th17 cell immune responses

BACKGROUND

Probiotics are a potentially effective therapy for inflammatory bowel disease (IBD); IBD is linked to impaired gut microbiota and intestinal immunity. However, the utilization of an antibiotic cocktail (Abx) prior to the probiotic intervention remains controversial. This study aims to identify the effect of Abx pretreatment from dextran sulfate sodium (DSS)-induced colitis and to evaluate whether Abx pretreatment has an enhanced effect on the protection of Clostridium butyricum Miyairi588 (CBM) from colitis.

RESULTS

The inflammation, dysbiosis, and dysfunction of gut microbiota as well as T cell response were both enhanced by Abx pretreatment. Additionally, CBM significantly alleviated the DSS-induced colitis and impaired gut epithelial barrier, and Abx pretreatment could enhance these protective effects. Furthermore, CBM increased the benefit bacteria abundance and short-chain fatty acids (SCFAs) level with Abx pretreatment. CBM intervention after Abx pretreatment regulated the imbalance of cytokines and transcription factors, which corresponded to lower infiltration of Th1 and Th17 cells, and increased Th2 cells.

CONCLUSIONS

Abx pretreatment reinforced the function of CBM in ameliorating inflammation and barrier damage by increasing beneficial taxa, eliminating pathogens, and inducing a protective Th2 cell response. This study reveals a link between Abx pretreatment, microbiota, and immune response changes in colitis, which provides a reference for the further application of Abx pretreatment before microbiota-based intervention.

TSP50 Attenuates DSS-Induced Colitis by Regulating TGF-β Signaling Mediated Maintenance of Intestinal Mucosal Barrier Integrity

The integrity of the intestinal mucosal barrier is crucial for protecting the intestinal epithelium against invasion by commensal bacteria and pathogens, thereby combating colitis. The investigation revealed that the absence of TSP50 compromised the integrity of the intestinal mucosal barrier in murine subjects. This disruption facilitated direct contact between intestinal bacteria and the intestinal epithelium, thereby increasing susceptibility to colitis. Mechanistic analysis indicated that TSP50 deficiency in intestinal stem cells (ISCs) triggered aberrant activation of the TGF-β signaling pathway and impeded the differentiation of goblet cells in mice, leading to impairment of mucosal permeability. By inhibiting the TGF-β pathway, the functionality of the intestinal mucosal barrier is successfully restored and mitigated colitis in TSP50-deficient mice. In conclusion, TSP50 played a crucial role in maintaining the intestinal mucosal barrier function and exhibited the preventive effect against the development of colitis by regulating the TGF-β signaling pathway.

Astragalus polysaccharide protects experimental colitis through an aryl hydrocarbon receptor-dependent autophagy mechanism

BACKGROUND AND PURPOSE

Disruption of intestinal barriers plays a vital role in the pathogenesis of colitis. The aryl hydrocarbon receptor (AhR) is a recognition sensor that mediates intestinal immune homeostasis and minimizes intestinal inflammation. Astragalus polysaccharide (APS) exerts pharmacological actions in colitis; however, the mechanism has not been elucidated. We investigated whether APS protects through AhR-dependent autophagy.

EXPERIMENTAL APPROACH

The symptoms of dextran sulfate sodium (DSS)-induced colitis in mice involving intestinal barrier function and inflammatory injury were evaluated after APS administration. Intestinal-specific Becn1 conditional knockout (Becn1 cKO) mice were constructed and compared with wild-type mice. Autophagy and the effects of APS were investigated after the deactivation of AhRs. The relationship between APS-induced AhRs and autophagic Becn1 was investigated using a dual-luciferase reporter system and chromatin immunoprecipitation (ChIP)-quantitative polymerase chain reaction assay. Caco-2 cells were used to investigate inflammatory responses and AhR-dependent autophagy.

KEY RESULTS

APS improved intestinal barrier function in inflammatory injury in colitis mice. APS triggered autophagic flow; however, knockout of Becn1 in the gut increased susceptibility to colitis, leading to diminished epithelial barrier function and severe intestinal inflammation, impairing the protective effects of APS. Mechanistically, APS-triggered autophagy depends on AhR expression. Activated AhR binds to the promoter Becn1 to operate transcription of genes involved in anti-inflammation and intestinal barrier repair, while deactivation of AhR correlated with intestinal inflammation and the therapeutic function of APS.

CONCLUSIONS AND IMPLICATIONS

APS protects colitis mice by targeting autophagy, especially as the AhR stimulates the repair of damaged intestinal barrier functions.

Colonic ketogenesis, a microbiota-regulated process, contributes to blood ketones and protects against colitis in mice

Ketogenesis is considered to occur primarily in liver to generate ketones as an alternative energy source for non-hepatic tissues when glucose availability/utilization is impaired. 3-Hydroxy-3-methylglutaryl-CoA synthase-2 (HMGCS2) mediates the rate-limiting step in this mitochondrial pathway. Publicly available databases show marked down-regulation of HMGCS2 in colonic tissues in Crohn's disease and ulcerative colitis. This led us to investigate the expression and function of this pathway in colon and its relevance to colonic inflammation in mice. Hmgcs2 is expressed in cecum and colon. As global deletion of Hmgcs2 showed significant postnatal mortality, we used a conditional knockout mouse with enzyme deletion restricted to intestinal tract. These mice had no postnatal mortality. Fasting blood ketones were lower in these mice, indicating contribution of colonic ketogenesis to circulating ketones. There was also evidence of gut barrier breakdown and increased susceptibility to experimental colitis with associated elevated levels of IL-6, IL-1β, and TNF-α in circulation. Interestingly, many of these phenomena were mostly evident in male mice. Hmgcs2 expression in colon is controlled by colonic microbiota as evidenced from decreased expression in germ-free mice and antibiotic-treated conventional mice and from increased expression in a human colonic epithelial cell line upon treatment with aqueous extracts of cecal contents. Transcriptomic analysis of colonic epithelia from control mice and Hmgcs2-null mice indicated an essential role for colonic ketogenesis in the maintenance of optimal mitochondrial function, cholesterol homeostasis, and cell-cell tight-junction organization. These findings demonstrate a sex-dependent obligatory role for ketogenesis in protection against colonic inflammation in mice.

Protective Effect of the Polyphenol Ligustroside on Colitis Induced with Dextran Sulfate Sodium in Mice

Dietary polyphenols are reported to alleviate colitis by interacting with gut microbiota which plays an important role in maintaining the integrity of the intestinal barrier. As a type of dietary polyphenol, whether ligustroside (Lig) could alleviate colitis has not been explored yet. Here, we aimed to determine if supplementation of ligustroside could improve colitis. We explored the influence of ligustroside intake with different dosages on colitis induced with dextran sulfate sodium (DSS). Compared to the DSS group, supplementation of ligustroside could reduce body weight (BW) loss, decrease disease activity indices (DAI), and relieve colon damage in colitis mice. Furthermore, ligustroside intake with 2 mg/kg could decrease proinflammatory cytokine concentrations in serum and increase immunoglobulin content and antioxidant enzymes in colon tissue. In addition, supplementation of ligustroside (2 mg/kg) could reduce mucus secretion and prevent cell apoptosis. Also, changes were revealed in the bacterial community composition, microbiota functional profiles, and intestinal metabolite composition following ligustroside supplementation with 2 mg/kg using 16S rRNA sequencing and non-targeted lipidomics analysis. In conclusion, the results showed that ligustroside was very effective in preventing colitis through reduction in inflammation and the enhancement of the intestinal barrier. Furthermore, supplementation with ligustroside altered the gut microbiota and lipid composition of colitis mice.

Propionibacterium freudenreichii CIRM-BIA 129 mitigates colitis through S layer protein B-dependent epithelial strengthening

The growing incidence of human diseases involving inflammation and increased gut permeability makes the quest for protective functional foods more crucial than ever. Propionibacterium freudenreichii (P. freudenreichii) is a beneficial bacterium used in the dairy and probiotic industries. Selected strains exert anti-inflammatory effects, and the present work addresses whether the P. freudenreichii CIRM-BIA129, consumed daily in a preventive way, could protect mice from acute colitis induced by dextran sodium sulfate (DSS), and more precisely, whether it could protect from intestinal epithelial breakdown induced by inflammation. P. freudenreichii CIRM-BIA129 mitigated colitis severity and inhibited DSS-induced permeability. It limited crypt length reduction and promoted the expression of zonula occludens-1 (ZO-1), without reducing interleukin-1β mRNA (il-1β) expression. In vitro, P. freudenreichii CIRM-BIA129 prevented the disruption of a Caco-2 monolayer induced by proinflammatory cytokines. It increased transepithelial electrical resistance (TEER) and inhibited permeability induced by inflammation, along with an increased ZO-1 expression. Extracellular vesicles (EVs) from P. freudenreichii CIRM-BIA129, carrying the surface layer protein (SlpB), reproduced the protective effect of P. freudenreichii CIRM-BIA129. A mutant strain deleted for slpB (ΔslpB), or EVs from this mutant strain, had lost their protective effects and worsened both DSS-induced colitis and inflammation in vivo. These results shown that P. freudenreichii CIRM-BIA129 daily consumption has the potential to greatly alleviate colitis symptoms and, particularly, to counter intestinal epithelial permeability induced by inflammation by restoring ZO-1 expression through mechanisms involving S-layer protein B. They open new avenues for the use of probiotic dairy propionibacteria and/or postbiotic fractions thereof, in the context of gut permeability.NEW & NOTEWORTHY Propionibacterium freudenreichii reduces dextran sodium sulfate (DSS)-induced intestinal permeability in vivo. P. freudenreichii does not inhibit inflammation but damages linked to inflammation. P. freudenreichii inhibits intestinal epithelial breakdown through S-layer protein B. The protective effects of P. freudenreichii depend on S-layer protein B. Extracellular vesicles from P. freudenreichii CB 129 mimic the protective effect of the probiotic.

Dietary Zinc Ameliorates TNBS-Induced Colitis in Mice Associated with Regulation of Th1/Th2/Th17 Balance and NF-κB/NLRP3 Signaling Pathway

Inflammatory bowel diseases (IBDs), including Crohn's disease and ulcerative colitis, are chronic relapsing inflammatory gastrointestinal tract diseases of uncertain origin, which are frequently associated with zinc deficiency. Animal models have a considerable value in elucidating the process of IBD. In this study, 50 male C57BL/6 J mice were randomly assigned to five groups: control group (Con), 2,4,6-trinitrobenzenesulfonic acid (TNBS) group, and three zinc supplementation groups, namely 160 ppm group, 400 ppm group, and 1000 ppm group. The results showed that supplementation of dietary zinc with zinc oxide could effectively relieve the severity of ulcerative colitis induced by TNBS in mice. We demonstrate that the protective mechanism involves the immunomodulation of dietary zinc by increasing CD3+, CD3+CD8+, and Th2 cells, suppressing Th1 and Th17 cells, and decreasing the production of serum IL-1β and IL-18. The dietary zinc oxide seems to be able to suppress the NF-κB/NLRP3 signaling pathway by downregulating the mRNA and protein expression of NIK, IKK, NF-κB, and NLRP3. The results suggest that dietary supplementation of zinc oxide may protect against colitis, and proper daily zinc supplementation may reduce the risk of IBD.

The attenuating effect of fermented soymilk on DSS-induced colitis in mice by suppressing immune response and modulating gut microbiota

Fermented soymilk (FSM) as a new plant-based yoghurt has attracted attention for its nutritional and health benefits. The aim of this research is to explore the effect of consuming FSM before and during inflammatory bowel disease (IBD) on intestinal immune response, and to assess whether fermentation and sucrose can improve the anti-inflammatory activity of soymilk (SM) and FSM, and finally clarify their effect on the gut microbiota and levels of short-chain fatty acids (SCFAs). Consuming FSM in advance can effectively alleviate weight loss and bloody stools in mice with colitis and is associated with a 27% colon length repair rate. It can also prevent spleen and liver enlargement, inhibit immune response and oxidative stress, and increase the expression of the tight junction protein occludin gene (60%). Meanwhile, intaking FSM during IBD reduced weight loss, prevented liver damage, and repaired colon injury. In addition, fermentation enhance the inhibitory effects of FSM on colitis, whereas adding 3% sucrose to FSM had no effect on its intervention in colitis. Analysis of the composition of the gut microbiota in mice showed that the intake of FSM reduced the relative abundance of the pathogenic bacteria Parasutterella, Turicibater, and Bacteroide by 75%, 62%, and 50%, respectively, and increased the relative abundance of the beneficial bacteria Akkermansiaceae, Lachnospiraceae, Alloprevotella, and Dubosella by 28%, 50%, 80%, and 63%, respectively. It further restored the levels of SCFAs in the mouse intestine. The results provide a scientific basis for FSM as a natural anti-inflammatory food that can improve inflammatory intestinal microbiota imbalance and promote gut health.

Myeloid deletion of talin-1 reduces mucosal macrophages and protects mice from colonic inflammation

The intestinal immune response is crucial in maintaining a healthy gut, but the enhanced migration of macrophages in response to pathogens is a major contributor to disease pathogenesis. Integrins are ubiquitously expressed cellular receptors that are highly involved in immune cell adhesion to endothelial cells while in the circulation and help facilitate extravasation into tissues. Here we show that specific deletion of the Tln1 gene encoding the protein talin-1, an integrin-activating scaffold protein, from cells of the myeloid lineage using the Lyz2-cre driver mouse reduces epithelial damage, attenuates colitis, downregulates the expression of macrophage markers, decreases the number of differentiated colonic mucosal macrophages, and diminishes the presence of CD68-positive cells in the colonic mucosa of mice infected with the enteric pathogen Citrobacter rodentium. Bone marrow-derived macrophages lacking expression of Tln1 did not exhibit a cell-autonomous phenotype; there was no impaired proinflammatory gene expression, nitric oxide production, phagocytic ability, or surface expression of CD11b, CD86, or major histocompatibility complex II in response to C. rodentium. Thus, we demonstrate that talin-1 plays a role in the manifestation of infectious colitis by increasing mucosal macrophages, with an effect that is independent of macrophage activation.

Oat Peptides Alleviate Dextran Sulfate Sodium Salt-Induced Colitis by Maintaining the Intestinal Barrier and Modulating the Keap1-Nrf2 Axis

The prevalence of inflammatory bowel disease (IBD) is progressively rising each year, emphasizing the significance of implementing rational dietary interventions for disease prevention. Oats, being a staple agricultural product, are abundant in protein content. This study aimed to investigate the protective effects and underlying mechanisms of oat peptides (OPs) in a mouse model of acute colitis induced by dextran sulfate sodium salt (DSS) and a Caco-2 cell model. The findings demonstrated that intervention with OPs effectively mitigated the symptoms associated with DSS-induced colitis. The physicochemical characterization analysis demonstrated that the molecular weight of the OPs was predominantly below 5 kDa, with a predominant composition of 266 peptides. This study provides further evidence of the regulatory impact of OPs on the Keap1-Nrf2 signaling axis and elucidates the potential role of WGVGVRAERDA as the primary bioactive peptide responsible for the functional effects of OPs. Ultimately, the results of this investigation demonstrate that OPs effectively mitigate DSS-induced colitis by preserving the integrity of the intestinal barrier and modulating the Keap1-Nrf2 axis. Consequently, these findings establish a theoretical foundation for the utilization of OPs as dietary supplements to prevent the onset of IBD.

Identification of a functional peptide of a probiotic bacterium-derived protein for the sustained effect on preventing colitis

Several probiotic-derived factors have been identified as effectors of probiotics for exerting beneficial effects on the host. However, there is a paucity of studies to elucidate mechanisms of their functions. p40, a secretory protein, is originally isolated from a probiotic bacterium, Lactobacillus rhamnosus GG. Thus, this study aimed to apply structure-functional analysis to define the functional peptide of p40 that modulates the epigenetic program in intestinal epithelial cells for sustained prevention of colitis. In silico analysis revealed that p40 is composed of a signal peptide (1-28 residues) followed by a coiled-coil domain with uncharacterized function on the N-terminus, a linker region, and a β-sheet domain with high homology to CHAP on the C-terminus. Based on the p40 three-dimensional structure model, two recombinant p40 peptides were generated, p40N120 (28-120 residues) and p40N180 (28-180 residues) that contain first two and first three coiled coils, respectively. Compared to full-length p40 (p40F) and p40N180, p40N120 showed similar or higher effects on up-regulating expression of Setd1b (encoding a methyltransferase), promoting mono- and trimethylation of histone 3 on lysine 4 (H3K4me1/3), and enhancing Tgfb gene expression and protein production that leads to SMAD2 phosphorylation in human colonoids and a mouse colonic epithelial cell line. Furthermore, supplementation with p40F and p40N120 in early life increased H3K4me1, Tgfb expression and differentiation of regulatory T cells (Tregs) in the colon, and mitigated disruption of epithelial barrier and inflammation induced by DSS in adult mice. This study reveals the structural feature of p40 and identifies a functional peptide of p40 that could maintain intestinal homeostasis.

1,25(OH)2D3 alleviates oxidative stress and inflammation through up-regulating HMGCS2 in DSS-induced colitis

BACKGROUND

Previous study found that supplements with active vitamin D3 alleviated experimental colitis. The objective of this study was to investigate the possible role of 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), a ketone synthase, on vitamin D3 protecting against experimental colitis.

METHODS

HMGCS2 and vitamin D receptor (VDR) were measured in UC patients. The effects of vitamin D deficiency (VDD) and exogenous 1,25(OH)2D3 supplementation on experimental colitis were investigated in dextran sulfate sodium (DSS)-treated mice. DSS-induced oxidative stress and inflammation were analyzed in HT-29 cells. HMGCS2 was detected in 1,25(OH)2D3-pretreated HT-29 cells and mouse intestines. HMGCS2 was silenced to investigate the role of HMGCS2 in 1,25(OH)2D3 protecting against experimental colitis.

RESULTS

Intestinal HMGCS2 downregulation was positively correlated with VDR reduction in UC patients. The in vivo experiments showed that VDD exacerbated DSS-induced colitis. By contrast, 1,25(OH)2D3 supplementation ameliorated DSS-induced colon damage, oxidative stress and inflammation. HMGCS2 was up-regulated after 1,25(OH)2D3 supplementation both in vivo and in vitro. Transfection with HMGCS2-siRNA inhibited antioxidant and anti-inflammatory effects of 1,25(OH)2D3 in DSS-treated HT-29 cells.

CONCLUSION

1,25(OH)2D3 supplementation up-regulates HMGCS2, which is responsible for 1,25(OH)2D3-mediated protection against oxidative stress and inflammation in DSS-induced colitis. These findings provide a potential therapeutic strategy for alleviating colitis-associated oxidative stress and inflammation.

Methyl cinnamate protects against dextran sulfate sodium-induced colitis in mice by inhibiting the MAPK signaling pathway

Effective and non-toxic therapeutic agents are lacking for the prevention and treatment of colitis. Previous studies found that methyl cinnamate (MC), extracted from galangal ( Alpinia officinarum Hance), has anti-inflammatory properties. However, whether MC is effective as anti-colitis therapy remains unknown. In this study, we investigate the therapeutic effects of MC on dextran sulfate sodium (DSS)-induced colitis in mice and further explore its potential mechanism of action. MC treatment relieves symptoms associated with DSS-induced colitis, including the recovery of DSS-induced weight loss, decreases the disease activity index score, and increases the colon length without toxic side effects. MC treatment protects the integrity of the intestinal barrier in mice with DSS-induced colitis and inhibits the overexpression of pro-inflammatory cytokines in vivo and in vitro. Moreover, the MAPK signaling pathway is found to be closely related to the treatment with MC of colitis. Western blot analysis show that phosphorylation of the p38 protein in colon tissues treated with MC is markedly reduced and phosphorylation levels of the p38, JNK and ERK proteins are significantly decreased in RAW 264.7 cells treated with MC, indicating that the mechanism of MC in treating DSS-induced colitis could be achieved by inhibiting the MAPK signaling pathway. Furthermore, 16S RNA sequencing analysis show that MC can improve intestinal microbial dysbiosis in mice with DSS-induced colitis. Altogether, these findings suggest that MC may be a novel therapeutic candidate with anti-colitis efficacy. Furthermore, MC treatment relieves the symptoms of colitis by inhibiting the MAPK signaling pathway and improving the intestinal microbiota.

Effect of Extracelluar Vesicles Derived from Akkermansia muciniphila on Intestinal Barrier in Colitis Mice

Inflammatory bowel disease (IBD) is a chronic and recurrent disease. It has been observed that the incidence and prevalence of IBD are increasing, which consequently raises the risk of developing colon cancer. Recently, the regulation of the intestinal barrier by probiotics has become an effective treatment for colitis. Akkermansia muciniphila-derived extracellular vesicles (Akk EVs) are nano-vesicles that contain multiple bioactive macromolecules with the potential to modulate the intestinal barrier. In this study, we used ultrafiltration in conjunction with high-speed centrifugation to extract Akk EVs. A lipopolysaccharide (LPS)-induced RAW264.7 cell model was established to assess the anti-inflammatory effects of Akk EVs. It was found that Akk EVs were able to be absorbed by RAW264.7 cells and significantly reduce the expression of nitric oxide (NO), TNF-α, and IL-1β (p < 0.05). We explored the preventative effects on colitis and the regulating effects on the intestinal barrier using a mouse colitis model caused by dextran sulfate sodium (DSS). The findings demonstrated that Akk EVs effectively prevented colitis symptoms and reduced colonic tissue injury. Additionally, Akk EVs significantly enhanced the effectiveness of the intestinal barrier by elevating the expression of MUC2 (0.53 ± 0.07), improving mucus integrity, and reducing intestinal permeability (p < 0.05). Moreover, Akk EVs increased the proportion of the beneficial bacteria Firmicutes (33.01 ± 0.09%) and downregulated the proportion of the harmful bacteria Proteobacteria (0.32 ± 0.27%). These findings suggest that Akk EVs possess the ability to regulate immune responses, protect intestinal barriers, and modulate the gut microbiota. The research presents a potential intervention approach for Akk EVs to prevent colitis.

Protective effect of Arum maculatum against dextran sulfate sodium induced colitis in rats

Ulcerative colitis (UC) is an inflammatory disease of the large intestine that is characterized by diarrhea, bloody stools, abdominal pain and mucosal ulceration. UC is treated with nonsteroidal anti-inflammatory drugs, corticosteroids or immunosuppressants, but long-term use of these drugs can cause adverse effects. Arum maculatum is used as a traditional treatment for digestive system disorders, but its use for treatment of UC has not been investigated rigorously. We investigated the possible protective effect of a methanol extract of A. maculatum against dextran sulfate sodium (DSS) induced experimental UC in rats. Total phenolic and flavonoid contents of the extract were 32.919 ± 1.125 mg gallic acid equivalent (GAE)/g and 52.045 ± 7.902 µg rutin equivalent (RE)/mg, respectively. The half-maximal inhibitory concentration (IC50) for the extract was 105.76 µg/ml according to the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity assay. Effects of A. maculatum extract on UC induced by DSS were assessed both macroscopically and histologically. We also investigated effects of A. maculatum extract on malondialdehyde (MDA) levels and the oxidative stress index (OSI) in normal rats and rats with UC. We found that treatment with A. maculatum extract protected the colon against DSS induced UC in a dose-dependent manner.

Epithelial IFNγ signalling and compartmentalized antigen presentation orchestrate gut immunity

All nucleated cells express major histocompatibility complex I and interferon-γ (IFNγ) receptor1, but an epithelial cell-specific function of IFNγ signalling or antigen presentation by means of major histocompatibility complex I has not been explored. We show here that on sensing IFNγ, colonic epithelial cells productively present pathogen and self-derived antigens to cognate intra-epithelial T cells, which are critically located at the epithelial barrier. Antigen presentation by the epithelial cells confers extracellular ATPase expression in cognate intra-epithelial T cells, which limits the accumulation of extracellular adenosine triphosphate and consequent activation of the NLRP3 inflammasome in tissue macrophages. By contrast, antigen presentation by the tissue macrophages alongside inflammasome-associated interleukin-1α and interleukin-1β production promotes a pathogenic transformation of CD4+ T cells into granulocyte-macrophage colony-stimulating-factor (GM-CSF)-producing T cells in vivo, which promotes colitis and colorectal cancer. Taken together, our study unravels critical checkpoints requiring IFNγ sensing and antigen presentation by epithelial cells that control the development of pathogenic CD4+ T cell responses in vivo.

Mucin levels in glands of the colonic mucosa of rats with diversion colitis subjected to enemas containing sucralfate and n-acetylcysteine alone or in combination

PURPOSE

To evaluate the tissue content of neutral and acidic mucins, sulfomucins and sialomucins in colonic glands devoid of intestinal transit after enemas containing sucralfate and n-acetylcysteine alone or in combination.

METHODS

Sixty-four rats underwent intestinal transit bypass. A colonic segment was collected to compose the white group (without intervention). After derivation, the animals were divided into two groups according to whether enemas were performed daily for two or four weeks. Each group was subdivided into four subgroups according to the substance used: control group: saline 0.9%; sucralfate group (SCF): SCF 2 g/kg/day; n-acetylcysteine group (NAC): NAC 100 mg/kg/day; and SCF+NAC group: SCF 2 g/kg/day + NAC 100 mg/kg/day.Neutral and acidic mucins were stained by periodic acid-Schiff and alcian-blue techniques, respectively. The distinction between sulfomucins and sialomucin was made by the high alcian-blue iron diamine technique. The content of mucins in the colonic glands was measured by computerized morphometry. The inflammatory score was assessed using a validated scale. The results between the groups were compared by the Mann-Whitney's test, while the variation according to time by the Kruskal-Wallis' test (Dunn's post-test). A significance level of 5% was adopted.

RESULTS

There was reduction in the inflammatory score regardless of the application of isolated or associated substances. Intervention with SCF+NAC increased the content of all mucin subtypes regardless of intervention time.

CONCLUSIONS

The application of SCF+NAC reduced the inflammatory process of the colonic mucosa and increased the content of different types of mucins in the colonic glands of segments excluded from fecal transit.

Hypusination Maintains Intestinal Homeostasis and Prevents Colitis and Carcinogenesis by Enhancing Aldehyde Detoxification

BACKGROUND & AIMS

The amino acid hypusine, synthesized from the polyamine spermidine by the enzyme deoxyhypusine synthase (DHPS), is essential for the activity of eukaryotic translation initiation factor 5A (EIF5A). The role of hypusinated EIF5A (EIF5AHyp) remains unknown in intestinal homeostasis. Our aim was to investigate EIF5AHyp in the gut epithelium in inflammation and carcinogenesis.

METHODS

We used human colon tissue messenger RNA samples and publicly available transcriptomic datasets, tissue microarrays, and patient-derived colon organoids. Mice with intestinal epithelial-specific deletion of Dhps were investigated at baseline and in models of colitis and colon carcinogenesis.

RESULTS

We found that patients with ulcerative colitis and Crohn's disease exhibit reduced colon levels of DHPS messenger RNA and DHPS protein and reduced levels of EIF5AHyp. Similarly, colonic organoids from colitis patients also show down-regulated DHPS expression. Mice with intestinal epithelial-specific deletion of Dhps develop spontaneous colon hyperplasia, epithelial proliferation, crypt distortion, and inflammation. Furthermore, these mice are highly susceptible to experimental colitis and show exacerbated colon tumorigenesis when treated with a carcinogen. Transcriptomic and proteomic analysis on colonic epithelial cells demonstrated that loss of hypusination induces multiple pathways related to cancer and immune response. Moreover, we found that hypusination enhances translation of numerous enzymes involved in aldehyde detoxification, including glutathione S-transferases and aldehyde dehydrogenases. Accordingly, hypusination-deficient mice exhibit increased levels of aldehyde adducts in the colon, and their treatment with a scavenger of electrophiles reduces colitis.

CONCLUSIONS

Hypusination in intestinal epithelial cells has a key role in the prevention of colitis and colorectal cancer, and enhancement of this pathway via supplementation of spermidine could have a therapeutic impact.

Isovitexin prevents DSS-induced colitis through inhibiting inflammation and preserving intestinal barrier integrity through activating AhR

Isovitexin (ISO) is a glycosylated flavonoid obtained from Asian rice that has been reported to have anti-inflammatory effect. However, the effects of ISO on colitis have not been reported. In the present study, we aimed to explore the protective effects of isovitexin on colitis using the dextran sodium sulfate (DSS)-induced model. In vitro, the protective mechanism was investigated in TNF-α-stimulated IEC cells. Inflammatory cytokines were measured by ELISA. The signaling pathways were measured by Western blot analysis. ISO attenuated DSS-induced colitis through reducing body weight loss and colonic histological changes. Also, the levels of TNF-α and IL-1β induced by DSS were inhibited by ISO. The MPO activity induced by DSS was attenuated by ISO. In vitro, ISO inhibited IL-6 and IL-1β production in TNF-α-stimulated cells. ISO increased the expression of tight junction proteins ZO-1 and occludin. Also, ISO inhibited TNF-α-induced NF-κB activation. In addition, ISO was found to increase the expression of aryl hydrocarbon receptor (AhR). And inhibition of AhR by its antagonist CH223191 could reverse these effects of ISO. ISO inhibited DSS-induced colitis in mice through suppressing inflammation and preserving intestinal barrier integrity through activating AhR. ISO may be useful as a potential therapeutic agent for colitis.

An oral cholera vaccine in the prevention and/or treatment of inflammatory bowel disease

The oral cholera vaccine WC-rBS consists of 4 different inactivated strains of Vibrio cholerae (LPS source) admixed with recombinant cholera toxin B subunit. Because of its unique composition and anti-inflammatory properties reported for both CTB and low doses of LPS from other Gram-negative bacteria, we speculated that WC-rBS might have anti-inflammatory potential in a chronic autoimmune disease such as inflammatory bowel diseases. First in vitro endotoxin tolerance experiments showed the surprising WC-rBS potential in the modulation of inflammatory responses on both PBMCs and THP1 cells. WC-rBS was further evaluated in the Dextran Sodium Sulfate colitis mouse model. Administrated orally at different dosages, WC-rBS vaccine was safe and showed immunomodulatory properties when administered in a preventive mode (before and during the induction of DSS colitis) as well as in a curative mode (after colitis induction); with improvement of disease activity index (from 27 to 73%) and histological score (from 65 to 88%). Interestingly, the highest therapeutic effect of WC-rBS vaccine was observed with the lowest dosage, showing even better anti-inflammatory properties than mesalamine; an approved 5-aminosalicylic acid drug for treating IBD patients. In summary, this is the first time that a prophylactic medicine, safe and approved for prevention of an infectious disease, showed a benefit in an inflammatory bowel disease model, potentially offering a novel therapeutic modality for IBD patients.

The improvement of intestinal dysbiosis and hepatic metabolic dysfunction in dextran sulfate sodium-induced colitis mice: effects of curcumin

BACKGROUND AND AIM

Curcumin may have promising application in the prevention and amelioration of inflammatory bowel disease (IBD). However, the underlying mechanisms underpinning the ability of curcumin to interact with the gut and liver in IBD remains to be defined, which is the exploration aim of this study.

METHODS

Mice with dextran sulfate sodium salt (DSS)-induced acute colitis were treated either with 100 mg/kg of curcumin or phosphate buffer saline (PBS). Hematoxylin-eosin (HE) staining, 16S rDNA Miseq sequencing, proton nuclear magnetic resonance (1 H NMR) spectroscopy, and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were applied for analysis. Spearman's correlation coefficient (SCC) was utilized to assess the correlation between the modification of intestinal bacteria and hepatic metabolite parameters.

RESULTS

Curcumin supplementation not only prevented further loss of body weight and colon length in IBD mice but also improved diseases activity index (DAI), colonic mucosal injury, and inflammatory infiltration. Meanwhile, curcumin restored the composition of the gut microbiota, significantly increased Akkermansia, Muribaculaceae_unclassified, and Muribaculum, and significantly elevated the concentration of propionate, butyrate, glycine, tryptophan, and betaine in the intestine. For hepatic metabolic disturbances, curcumin intervention altered 14 metabolites, including anthranilic acid and 8-amino-7-oxononanoate while enriching pathways related to the metabolism of bile acids, glucagon, amino acids, biotin, and butanoate. Furthermore, SCC analysis revealed a potential correlation between the upregulation of intestinal probiotics and alterations in liver metabolites.

CONCLUSION

The therapeutic mechanism of curcumin against IBD mice occurs by improving intestinal dysbiosis and liver metabolism disorders, thus contributing to the stabilization of the gut-liver axis.

Limosilactobacillus mucosae and Lactobacillus amylovorus Protect Against Experimental Colitis via Upregulation of Colonic 5-Hydroxytryptamine Receptor 4 and Transforming Growth Factor-β2

BACKGROUND

Limosilactobacillusmucosae (LM) exerts anti-inflammatory and health-promoting effects. However, its role in the modulation of gut serotonin or 5-hydroxytryptamine (5-HT) metabolism and 5-HT receptors (HTRs) in inflammation requires further investigation.

OBJECTIVES

We compared LM with Lactobacillus amylovorus (LA) for the regulation of 5-HT, HTRs, inflammatory mediators, and their correlations in the colon of mice with experimental colitis.

METHODS

Male C57BL/6 mice were randomly assigned to 6 groups: control (Con), LM, LA, dextran sodium sulfate (DSS), and DSS with pre-administration of LM (+LM) or LA (+LA). After 7 d of DSS treatment, mice were killed to analyze the expression of inflammatory mediators, HTRs, and concentrations of 5-HT and microbial metabolites in the colon.

RESULTS

LM was more effective than LA in alleviating DSS-induced colonic inflammation. Compared with mice in the DSS group, mice receiving DSS + LM or DSS + LA treatment had lower (P < 0.05) colonic mRNA expression of proinflammatory cytokines. DSS + LM treatment had lower mRNA expression of Il1b, Tnfa, and Ccl3, an abundance of p-STAT3, and greater expression of Tgfb2 and Htr4 in the colon (P < 0.05). The expression of inflammatory mediators (including Tgfb-1) was positively correlated (P < 0.05) with 5-HT and Htr2a and negatively correlated (P < 0.05) with Htr4. However, the expression of Tgfb-2 showed reversed correlations with the 5-HT and HTRs described above. Patterns for these correlations were different for LM and LA. Mice receiving the DSS + LM treatment had greater (P < 0.05) concentrations of acetate and valerate and lower (P < 0.05) concentrations of indole-3-acetic acid in the cecal and colonic contents.

CONCLUSIONS

LM showed greater efficacy than LA in alleviating DSS-induced colonic inflammation. The coordinated regulation of transforming growth factor-β subtypes and serotonin receptors in the colon may be one of the most important mechanisms underlying the probiotic effects of lactobacilli in gut inflammation.

Acetyl-11-keto-β-boswellic Acid Confers Protection in DSS-Induced Colitis via the JNK-p38 MAPK and NF-κB Signaling Pathways

The present study aims to explore the effect and mechanism of acetyl-11-keto-β-boswellic acid (AKBA) on inflammatory bowel disease (IBD). The IBD-mouse model is established by replacing normal water intake with 2.5% dextran sulfate sodium salt (DSS) aqueous solution, and 50 mg kg-1 of AKBA treatment is administered. The experimental mice are randomly divided into four groups, including control, AKBA , DSS, and DSS + AKBA groups. AKBA therapy conspicuously ameliorates the adverse symptoms caused by DSS in mice and inhibits the reduction of colon length and the rise of disease activity index score. Hematoxylin-eosin staining results suggest that AKBA strikingly improves the pathological conditions of the colon and small intestine tissues in IBD mice. AKBA prominently inhibits the DSS-induced increase of proinflammatory factor contents and the upregulation of the c-Jun N-terminal kinase (JNK)-p38/mitogen-activated protein kinase (MAPK) and Nuclear factor kappa B (NF-κB) pathways' protein levels in the colon tissues of IBD mice. AKBA alleviates DSS-induced colonic inflammatory injury in IBD mice by repressing the activation of the JNK-p38/MAPK and NF-κB pathways.

Intestinal Tr1 Cells Confer Protection against Colitis in the Absence of Foxp3+ Regulatory T Cell-Derived IL-10

The intestinal mucosa is continually exposed to diverse microbial and dietary Ags, requiring coordinated efforts by specialized populations of regulatory T cells (Tregs) to maintain homeostasis. Suppressive mechanisms used by intestinal Tregs include the secretion of anti-inflammatory cytokines such as IL-10 and TGF-β. Defects in IL-10 signaling are associated with severe infantile enterocolitis in humans, and mice deficient in IL-10 or its receptors develop spontaneous colitis. To determine the requirement of Foxp3+ Treg-specific IL-10 for protection against colitis, we generated Foxp3-specific IL-10 knockout (KO) mice (IL-10 conditional KO [cKO] mice). Colonic Foxp3+ Tregs isolated from IL-10cKO mice showed impaired ex vivo suppressive function, although IL-10cKO mice maintained normal body weights and developed only mild inflammation over 30 wk of age (in contrast to severe colitis in global IL-10KO mice). Protection from colitis in IL-10cKO mice was associated with an expanded population of IL-10-producing type 1 Tregs (Tr1, CD4+Foxp3-) in the colonic lamina propria that produced more IL-10 on a per-cell basis compared with wild-type intestinal Tr1 cells. Collectively, our findings reveal a role for Tr1 cells in the gut, as they expand to fill a tolerogenic niche in conditions of suboptimal Foxp3+ Treg-mediated suppression and provide functional protection against experimental colitis.

Hydroxysafflor yellow A protects against colitis in mice by suppressing pyroptosis via inhibiting HK1/NLRP3/GSDMD and modulating gut microbiota

Hydroxysafflor yellow A (HSYA), a chalcone glycoside, is a component of Carthamus tinctorius L. and exerts anti-inflammatory and antioxidative effects. However, the therapeutic effect and the underlying mechanism of HSYA on ulcerative colitis is unclear. This study aimed to investigate the unexplored protective effects and underlying mechanisms of HSYA on UC. In vitro analyses showed that HSYA reduced the secretion of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-6 and inhibited nucleotide-binding and oligomerization domain-like receptor protein 3 (NLRP3)/gasdermin D (GSDMD)-mediated pyroptosis in lipopolysaccharide/ adenosine-5'-triphosphate (LPS/ATP)-stimulated macrophages. Gas chromatography-mass spectrometry (GC-MS) profiling of intracellular metabolites showed that HSYA reduced the increased levels of glucose, glucose 6-phosphate, and lactic acid, and inhibited the increased hexokinase 1 (HK1) expression caused by LPS/ATP stimulation. HK1 shRNA transfection further confirmed that HSYA inhibited the NLRP3/GSDMD-mediated pyroptosis via HK1 downregulation. In vivo analyses showed that HSYA drastically attenuated UC symptoms by relieving body weight loss, a decline in colon length, and inflammatory infiltration in colonic tissues induced by dextran sulfate sodium (DSS). HSYA also reduced the secretion of pro-inflammatory cytokines including IL-1β, IL-6, TNF-α, and IL-18. Moreover, HSYA inhibited HK1/NLRP3/GSDMD-mediated pyroptosis in DSS-induced colitis mice. Finally, 16S rRNA sequencing analyses of gut microbiota revealed that HSYA reversed gut microbiota dysbiosis by reducing the abundance of Proteobacteria and increasing that of Bacteroidetes. This study demonstrated that HSYA not only exerted anti-inflammatory effects by inhibiting HK1/NLRP3/GSDMD and suppressing pyroptosis but also regulated gut microbiota in mice with DSS-induced colitis. Our findings provide new experimental evidence that HSYA might be a potential candidate for treating inflammatory bowel diseases.

Preventive and synbiotic effects of the soluble dietary fiber obtained from Lentinula edodes byproducts and Lactobacillus plantarum LP90 against dextran sulfate sodium-induced colitis in mice

BACKGROUND

Soluble dietary fiber (SDF) obtained from Lentinula edodes byproducts has beneficial effects on human intestinal health. This study aimed to examine the combined preventive and ameliorative effects of a kind of synbiotic (SDF with a molecular weight of 1.58 × 10²  kDa and Lactobacillus plantarum LP90 (LP) at 1 × 10⁹  CFU kg^-1 ) on dextran sulfate sodium-induced colitis mice.

RESULTS

The results demonstrated that synbiotic treatment could alleviate weight loss, decrease the disease activity index level and cause histological amelioration. Synbiotic treatment also promoted the production of goblet cells, increased the expression of tight junction proteins, and adjusted the production of myeloperoxidase, malondialdehyde and superoxide dismutase to repair intestinal epithelial injury. Clinical symptoms were alleviated by maintaining Th17/Treg balance, increasing interleukin 10 and immunoglobulin A levels, reducing interleukin 17a and tumor necrosis factor α production, and promoting mRNA to highly express of Foxp3 and vitamin D receptors. Moreover, synbiotic treatment could upregulate butyric acid production (4.71 ± 0.46 mol g^-1 feces, P < 0.05) and diversity of intestinal microbial to maintain intestinal homeostasis.

CONCLUSION

This study suggested that the combination of LP and SDF as a synbiotic has the potential for use as a nutritional supplement to alleviate colitis. © 2022 Society of Chemical Industry.

Schisandra chinensis (Turcz.) Baill. Protects against DSS-induced colitis in mice: Involvement of TLR4/NF-κB/NLRP3 inflammasome pathway and gut microbiota

ETHNOPHARMACOLOGICAL RELEVANCE

the fruit of Schisandra chinensis (Turcz.) Baill. (SC) is an important traditional Chinese herbal medicine, which has been widely used in traditional Chinese medicine (TCM) for treating intestinal diseases. It is also traditionally used as health product and medicine in Russia and other countries. However, the effect of SC ethanol extract on anti-ulcerative colitis (UC) has not been systematically studied yet.

AIM OF THE STUDY

We investigated the protective effects and underlying action mechanisms of SC extract (SCE) for UC treatment.

MATERIALS AND METHODS

An animal model of UC induced by dextran sulfate sodium (DSS) was established. After oral administration of SCE, the Disease Activity Index (DAI) was calculated, the length of colon measured, levels of proinflammatory factors determined, and histopathology carried out to assess the therapeutic efficacy of SCE on UC. The effects of SCE on the toll-like receptor 4/nuclear factor-kappa B/nucleotide-binding and oligomerization domain-like receptor family pyrin domain containing 3 inflammasome (TLR4/NF-κB/NLRP3 inflammasome) signaling pathway were evaluated by western blotting. High-throughput sequencing was done to reveal the effect of SCE on the change of the gut microbiota (GM) in mice with DSS-induced colitis.

RESULTS

SCE significantly reduced the DAI score, restored colon-length shortening, and ameliorated colonic histopathologic injury in mice with DSS-induced colitis. SCE inhibited the inflammatory response by regulating the TLR4/NF-κB/NLRP3 inflammasome pathway in mice with UC. SCE also maintained gut barrier function by increasing the levels of zonula occludens (ZO)-1 and occludin. 16S rRNA sequencing showed that SCE could reverse the GM imbalance caused by UC.

CONCLUSIONS

SCE can ameliorate DSS-induced colitis, and that its effects might be associated with suppression of the TLR4/NF-κB/NLRP3 inflammasome pathway and GM regulation, which may provide significant supports for the development of potential candidates for UC treatment.

Aloin A prevents ulcerative colitis in mice by enhancing the intestinal barrier function via suppressing the Notch signaling pathway

BACKGROUND

Previous studies reported that Aloe vera ameliorated DSS-induced colitis and promoted mucus secretion. However, the effect of Aloin A (AA), a major compound of Aloe vera, on colitis and its exact mechanism remains uncovered.

METHODS

C57BL/6 mice were successively subjected to 3% DSS solution for 5 days and distilled water for 2 days. Concurrently, AA (25, 50 mg/kg) and 5-aminosalicylic (500 mg/kg) were administrated intragastrically from day 1 to day 7. Colitis was evaluated by disease active index (DAI), colon length, inflammation response, and intestinal barrier function. In vitro LS174T cells challenged with 50 ng/ml of lipopolysaccharides (LPS) were used to validate the modulatory action of AA on the Notch signaling pathway.

RESULTS

Our results showed that oral administration with AA prominently prevented DSS-induced colitis symptoms in terms of decreased DAI, prevention of colon shortening, and reduced pathological damage. AA mitigated the inflammatory response evidenced by the decreased proinflammatory cytokines (TNF-α, IL-1β, IL-6) and increased anti-inflammatory cytokine (IL-10). Besides, AA inhibited apoptosis and facilitated proliferation in colons. Moreover, AA treatment up-regulated the expression of tight junction (TJ) proteins (ZO-1, Occludin) and promoted the secretion of MUC2 to decrease colon permeability. Mechanistically, AA inhibited the Notch pathway to promote the secretion of MUC2, which was consistent with LPS-challenged LS174 cells.

CONCLUSION

These results suggested that AA could prevent colitis by enhancing the intestinal barrier function via suppressing the Notch signaling pathway. Thus, AA might be a prospective remedy for ulcerative colitis.

Siderophore Immunization Restricted Colonization of Adherent-Invasive Escherichia coli and Ameliorated Experimental Colitis

Inflammatory bowel diseases (IBD) are characterized by chronic inflammation of the gastrointestinal tract and profound alterations to the gut microbiome. Adherent-invasive Escherichia coli (AIEC) is a mucosa-associated pathobiont that colonizes the gut of patients with Crohn's disease, a form of IBD. Because AIEC exacerbates gut inflammation, strategies to reduce the AIEC bloom during colitis are highly desirable. To thrive in the inflamed gut, Enterobacteriaceae acquire the essential metal nutrient iron by producing and releasing siderophores. Here, we implemented an immunization-based strategy to target the siderophores enterobactin and its glucosylated derivative salmochelin to reduce the AIEC bloom in the inflamed gut. Using chemical (dextran sulfate sodium) and genetic (Il10^-/- mice) IBD mouse models, we showed that immunization with enterobactin conjugated to the mucosal adjuvant cholera toxin subunit B potently elicited mucosal and serum antibodies against these siderophores. Siderophore-immunized mice exhibited lower AIEC gut colonization, diminished AIEC association with the gut mucosa, and reduced colitis severity. Moreover, Peyer's patches and the colonic lamina propria harbored enterobactin-specific B cells that could be identified by flow cytometry. The beneficial effect of siderophore immunization was primarily B cell-dependent because immunized muMT^-/- mice, which lack mature B lymphocytes, were not protected during AIEC infection. Collectively, our study identified siderophores as a potential therapeutic target to reduce AIEC colonization and its association with the gut mucosa, which ultimately may reduce colitis exacerbation. Moreover, this work provides the foundation for developing monoclonal antibodies against siderophores, which could provide a narrow-spectrum strategy to target the AIEC bloom in Crohn's disease patients. IMPORTANCE Adherent-invasive Escherichia coli (AIEC) is abnormally prevalent in patients with ileal Crohn's disease and exacerbates intestinal inflammation, but treatment strategies that selectively target AIEC are unavailable. Iron is an essential micronutrient for most living organisms, and bacterial pathogens have evolved sophisticated strategies to capture iron from the host environment. AIEC produces siderophores, small, secreted molecules with a high affinity for iron. Here, we showed that immunization to elicit antibodies against siderophores promoted a reduction of the AIEC bloom, interfered with AIEC association with the mucosa, and mitigated colitis in experimental mouse models. We also established a flow cytometry-based approach to visualize and isolate siderophore-specific B cells, a prerequisite for engineering monoclonal antibodies against these molecules. Together, this work could lead to a more selective and antibiotic-sparing strategy to target AIEC in Crohn's disease patients.

Protective effect of Schistosoma japonicum eggs on TNBS-induced colitis is associated with regulating Treg/Th17 balance and reprogramming glycolipid metabolism in mice

Inflammatory bowel diseases (IBDs) have been classified as modern refractory diseases. However, safe, well-tolerated, and effective treatments for IBDs are still lacking. Therefore, there is an urgent need to develop novel therapeutic targets with fewer undesirable adverse reactions. A growing body of research has shown that infection with live helminths or exposure to defined helminth-derived components can downregulate pathogenic inflammation due to their immunoregulatory ability. Here we were to explore the protective role of Schistosoma japonicum eggs on murine experimental colitis caused by trinitrobenzene sulfonic acid (TNBS) and the underlying mechanism. Frequencies of splenic Treg and Th17 cells were detected by flow cytometry. Protein and mRNA expressions of Foxp3 and RORγt were investigated by Western Blot and quantitative real-time polymerase chain reaction (qPCR), respectively. Concentrations of transforming growth factor-beta1 (TGF-β1), interleukin-10 (IL-10) and IL-17A were assessed with ELISA. Expression levels of genes related to glycolipid metabolism were measured with qPCR. The results showed that pre-exposure to S. japonicum eggs contributed to the relief of colitis in the TNBS model, evidenced by improved body weight loss, reversing spleen enlargement and colon shortening, and decreased histology scores. Compared with the TNBS group, the TNBS+Egg group had increased Treg immune response, accompanied by decreased Th17 immune response, leading to the reconstruction of Treg/Th17 balance. In addition, a ratio of Treg/Th17 was correlated negatively with the histological scores in the experiment groups. Furthermore, the regulation of Treg/Th17 balance by S. japonicum eggs was associated with inhibiting the glycolysis pathway and lipogenesis, along with promoting fatty acid oxidation in the TNBS+Egg group. These data indicate that S. japonicum eggs have a protective effect against TNBS-induced colitis, which is related to restoring Treg/Th17 balance and regulating glucose and lipid metabolism.

Lycium barbarum Glycopeptide prevents the development and progression of acute colitis by regulating the composition and diversity of the gut microbiota in mice

In most cases, recurrent chronic colitis is caused by the recurrence of acute colitis after incomplete recovery and re-exposure to irritating factors, and the gut microbiome, which is the largest micro-ecosystem in the human body, plays a crucial role in the development of colitis. Plant polysaccharides have always been reported to have the ability for anti-inflammation, and they are closely related to the gut microbiome. Lycium barbarum Glycopeptide (LbGP), the most potent component obtained by further isolation and purification from Lycium barbarum fruit, has been shown to inhibit inflammation in animal models. However, its therapeutic efficacy in colitis and its mechanism in gut microbiota regulation have not been fully studied. In our study, the dextran sulfate sodium (DSS)-induced mouse model was used to dynamically evaluate the effect of LbGP in the treatment of acute colitis and the mechanism from the perspective of the gut microbiome through the 16S rDNA sequence. The results showed that LbGP treatment significantly alleviated acute colitis and improved the gut microbiome compared with that in the model group. Harmful bacteria, such as Lachnoclostridium spp. and Parabacteroides_distasonis, were inhibited and probiotics, such as Bacteroides_acidifaciens, Lactobacillus spp., Turicibacter spp., and Alistipes spp., were increased by LbGP treatment. Further, a Random Forest analysis with 10-fold cross-validation identified a family named Muribaculaceae representing colitis development and recovery upon LbGP treatment. In conclusion, our study demonstrated the capability of LbGP to prevent the development of acute colitis by regulating the composition and diversity of the gut microbiota and highlighted the dynamic process of gut microbiota with the colitis progression. Further, it provides evidence to develop LbGP as a functional food supplement and future drug acting on intestinal disease.

Prevention of Ulcerative Colitis in Mice by Sweet Tea (Lithocarpus litseifolius) via the Regulation of Gut Microbiota and Butyric-Acid-Mediated Anti-Inflammatory Signaling

Sweet tea (Lithocarpus litseifolius [Hance] Chun) is a new resource for food raw materials, with plenty of health functions. This study aimed to investigate the preventive effect and potential mechanism of sweet tea extract (STE) against ulcerative colitis (UC). Briefly, BABL/c mice were treated with STE (100 and 400 mg/kg) for 2 weeks to prevent 3% dextran sulfate sodium (DSS)-induced UC. It was found that STE supplementation significantly prevented DSS-induced UC symptoms; suppressed the levels of pro-inflammatory mediators, such as myeloperoxidase and tumor necrosis factor-α; increased the levels of anti-inflammatory cytokines; and up-regulated the expression of tight junction proteins (Zonula occludens-1 and Occludin). STE also altered the gut microbiota profile of UC mice by increasing Bacteroidetes, Lactobacillus, Akkermansia, Lachnospiraceae_NK4A136_group, and Alistipes and inhibiting Firmicutes, Proteobacteria, and Helicobacter, accompanied by a significant increase in the content of butyric acid. Moreover, STE increased the expression of G-protein-coupled receptor (GPR) 43 and GPR109A and inhibited the expression of histone deacetylase 3 (HDAC3) and nuclear factor-κB p65 (NF-κB p65) in the colon. In conclusion, this study indicated that STE has a good preventive effect on UC by regulating gut microbiota to activate butyrate-GPR-mediated anti-inflammatory signaling and simultaneously inhibit HDAC3/NF-κB inflammatory signaling.

Bacillus amyloliquefaciens Enriched Camel Milk Attenuated Colitis Symptoms in Mice Model

Fermented camel’s milk has various health beneficial prebiotics and probiotics. This study aimed to evaluate the preventive efficacy of Bacillus amyloliquefaciens enriched camel milk (BEY) in 2-, 4- and 6-Trinitrobenzenesulfonic acid (TNBS)-induced colitis mice models. To this end, the immune modulatory effects of Bacillus amyloliquefaciens (BA) on TNF-α challenged HT29 colon cells were estimated using the cell proliferation and cytokines ELISA method. BEY was prepared using the incubation method and nutritional value was quantified by comparing it to commercial yogurt. Furthermore, TNBS-induced colitis was established and the level of disease index, pathological scores, and inflammatory markers of BEY-treated mice using macroscopic and microscopic examinations, qPCR and immunoblot were investigated. The results demonstrate that BA is non-toxic to HT29 colon cells and balanced the inflammatory cytokines. BEY reduced the colitis disease index, and improved the body weight and colon length of the TNBS-induced mice. Additionally, Myeloperoxidase (MPO) and pro-inflammatory cytokines (IL1β, IL6, IL8 and TNF-α) were attenuated by BEY treatment. Moreover, the inflammatory progress mRNA and protein markers nuclear factor kappa B (NFκB), phosphatase and tensin homolog (PTEN), proliferating cell nuclear antigen (PCNA), cyclooxygenase-2 (COX-2) and occludin were significantly down-regulated by BEY treatment. Interestingly, significant suppression of PCNA was observed in colonic tissues using the immunohistochemical examination. Treatment with BEY increased the epigenetic (microRNA217) interactions with PCNA. In conclusion, the BEY clearly alleviated the colitis symptoms and in the future could be used to formulate a probiotic-based diet for the host gut health and control the inflammatory bowel syndrome in mammals.

Protective Role of Spermidine in Colitis and Colon Carcinogenesis

BACKGROUND & AIMS

Because inflammatory bowel disease is increasing worldwide and can lead to colitis-associated carcinoma (CAC), new interventions are needed. We have shown that spermine oxidase (SMOX), which generates spermidine (Spd), regulates colitis. Here we determined whether Spd treatment reduces colitis and carcinogenesis.

METHODS

SMOX was quantified in human colitis and associated dysplasia using quantitative reverse-transcription polymerase chain reaction and immunohistochemistry. We used wild-type (WT) and Smox-/- C57BL/6 mice treated with dextran sulfate sodium (DSS) or azoxymethane (AOM)-DSS as models of colitis and CAC, respectively. Mice with epithelial-specific deletion of Apc were used as a model of sporadic colon cancer. Animals were supplemented or not with Spd in the drinking water. Colonic polyamines, inflammation, tumorigenesis, transcriptomes, and microbiomes were assessed.

RESULTS

SMOX messenger RNA levels were decreased in human ulcerative colitis tissues and inversely correlated with disease activity, and SMOX protein was reduced in colitis-associated dysplasia. DSS colitis and AOM-DSS-induced dysplasia and tumorigenesis were worsened in Smox-/- vs WT mice and improved in both genotypes with Spd. Tumor development caused by Apc deletion was also reduced by Spd. Smox deletion and AOM-DSS treatment were both strongly associated with increased expression of α-defensins, which was reduced by Spd. A shift in the microbiome, with reduced abundance of Prevotella and increased Proteobacteria and Deferribacteres, occurred in Smox-/- mice and was reversed with Spd.

CONCLUSIONS

Loss of SMOX is associated with exacerbated colitis and CAC, increased α-defensin expression, and dysbiosis of the microbiome. Spd supplementation reverses these phenotypes, indicating that it has potential as an adjunctive treatment for colitis and chemopreventive for colon carcinogenesis.

Exosome-like nanoparticles from Mulberry bark prevent DSS-induced colitis via the AhR/COPS8 pathway

Bark protects the tree against environmental insults. Here, we analyzed whether this defensive strategy could be utilized to broadly enhance protection against colitis. As a proof of concept, we show that exosome-like nanoparticles (MBELNs) derived from edible mulberry bark confer protection against colitis in a mouse model by promoting heat shock protein family A (Hsp70) member 8 (HSPA8)-mediated activation of the AhR signaling pathway. Activation of this pathway in intestinal epithelial cells leads to the induction of COP9 Constitutive Photomorphogenic Homolog Subunit 8 (COPS8). Utilizing a gut epithelium-specific knockout of COPS8, we demonstrate that COPS8 acts downstream of the AhR pathway and is required for the protective effect of MBELNs by inducing an array of anti-microbial peptides. Our results indicate that MBELNs represent an undescribed mode of inter-kingdom communication in the mammalian intestine through an AhR-COPS8-mediated anti-inflammatory pathway. These data suggest that inflammatory pathways in a microbiota-enriched intestinal environment are regulated by COPS8 and that edible plant-derived ELNs may hold the potential as new agents for the prevention and treatment of gut-related inflammatory disease.

Microbial enzymes induce colitis by reactivating triclosan in the mouse gastrointestinal tract

Emerging research supports that triclosan (TCS), an antimicrobial agent found in thousands of consumer products, exacerbates colitis and colitis-associated colorectal tumorigenesis in animal models. While the intestinal toxicities of TCS require the presence of gut microbiota, the molecular mechanisms involved have not been defined. Here we show that intestinal commensal microbes mediate metabolic activation of TCS in the colon and drive its gut toxicology. Using a range of in vitro, ex vivo, and in vivo approaches, we identify specific microbial β-glucuronidase (GUS) enzymes involved and pinpoint molecular motifs required to metabolically activate TCS in the gut. Finally, we show that targeted inhibition of bacterial GUS enzymes abolishes the colitis-promoting effects of TCS, supporting an essential role of specific microbial proteins in TCS toxicity. Together, our results define a mechanism by which intestinal microbes contribute to the metabolic activation and gut toxicity of TCS, and highlight the importance of considering the contributions of the gut microbiota in evaluating the toxic potential of environmental chemicals.

Lactate-utilizing bacteria ameliorates DSS-induced colitis in mice

Inflammatory bowel diseases (IBD) stem from alterations in the intestinal immune system and microbial dysbiosis, but the precise interactions between bacteria and IBD remain obscure. The commensal microbiota have a profound impact on human health and diseases. Here, we developed a selective culture medium for lactate-utilizing bacteria (LUB) that function as candidate probiotics to ameliorate IBD using a mouse model. Firstly, LUB, including Megasphaera, were enriched from human faeces using a selective medium with lactate. LUB efficiently attenuated the pathology of colitis induced by dextran sulphate sodium (DSS). Next, LUB administration counteracted the dysbiosis associated with the intestinal inflammatory process, and elevated the proportion of Escherichia-Shigella in intestines. Moreover, E. coli isolated from healthy faeces downstream recapitulated lactate-utilizing bacterial community to ameliorate the severity of DSS-induced acute colitis. In conclusion, our finding revealed that LUB were sufficient to exert inflammatory protection against colitis in mice, highlighting a novel therapeutic strategy to use LUB as potentially curable probiotics for therapeutic manipulation for IBD.

GPR120 Inhibits Colitis Through Regulation of CD4+ T Cell Interleukin 10 Production

BACKGROUND & AIMS

G protein-coupled receptor (GPR) 120 has been implicated in regulating metabolic syndromes with anti-inflammatory function. However, the role of GPR120 in intestinal inflammation is unknown. Here, we investigated whether and how GPR120 regulates CD4+ T cell function to inhibit colitis development.

METHODS

Dextran sodium sulfate (DSS)-induced colitis model, Citrobacter rodentium infection model, and CD4+ T cell adoptive transfer model were used to analyze the role of GPR120 in regulating colitis development. The effect of GPR120 on CD4+ T cell functions was analyzed by RNA sequencing, flow cytometry, and Seahorse metabolic assays. Mice were administered GPR120 agonist for investigating the potential of GPR120 agonist in preventing and treating colitis.

RESULTS

Deficiency of GPR120 in CD4+ T cells resulted in more severe colitis in mice upon dextran sodium sulfate insult and enteric infection. Transfer of GPR120-deficient CD4+CD45Rbhi T cells induced more severe colitis in Rag-/- mice with lower intestinal interleukin (IL) 10+CD4+ T cells. Treatment with the GPR120 agonist CpdA promoted CD4+ T cell production of IL10 by up-regulating Blimp1 and enhancing glycolysis, which was regulated by mTOR. GPR120 agonist-treated wild-type, but not IL10-deficient and Blimp1-deficient, T helper 1 cells induced less severe colitis. Furthermore, oral administration of GPR120 agonist protected mice from intestinal inflammation in both prevention and treatment schemes. Gpr120 expression was positively correlated with Il10 expression in the human colonic mucosa, including patients with inflammatory bowel diseases.

CONCLUSIONS

Our findings show the role of GPR120 in regulating intestinal CD4+ T cell production of IL10 to inhibit colitis development, which identifies GPR120 as a potential therapeutic target for treating inflammatory bowel diseases.

Relationship between IGF-1 and body weight in inflammatory bowel diseases: Cellular and molecular mechanisms involved

Inflammatory bowel diseases (IBD), represented by ulcerative colitis (UC) and Crohn's disease (CD), are characterized by chronic inflammation of the gastrointestinal tract, what leads to diarrhea, malnutrition, and weight loss. Depression of the growth hormone-insulin-like growth factor-1 axis (GH-IGF-1 axis) could be responsible of these symptoms. We demonstrate that long-term treatment (54 weeks) of adult CD patients with adalimumab (ADA) results in a decrease in serum IGF-1 without changes in serum IGF-1 binding protein (IGF1BP4). These results prompted us to conduct a preclinical study to test the efficiency of IGF-1 in the medication for experimental colitis. IGF-1 treatment of rats with DSS-induced colitis has a beneficial effect on the following circulating biochemical parameters: glucose, albumin, and total protein levels. In this experimental group we also observed healthy maintenance of colon size, body weight, and lean mass in comparison with the DSS-only group. Histological analysis revealed restoration of the mucosal barrier with the IGF-1 treatment, which was characterized by healthy quantities of mucin production, structural maintenance of adherers junctions (AJs), recuperation of E-cadherin and β-catenin levels and decrease in infiltrating immune cells and in metalloproteinase-2 levels. The experimentally induced colitis caused activation of apoptosis markers, including cleaved caspase 3, caspase 8, and PARP and decreases cell-cycle checkpoint activators including phosphorylated Rb, cyclin E, and E2F1. The IGF-1 treatment inhibited cyclin E depletion and partially protects PARP levels. The beneficial effects of IGF-1 in experimental colitis could be explained by a re-sensitization of the IGF-1/IRS-1/AKT cascade to exogenous IGF-1. Given these results, we postulate that IGF-1 treatment of IBD patients could prove to be successful in reducing disease pathology.

Defactinib inhibits PYK2 phosphorylation of IRF5 and reduces intestinal inflammation

Interferon regulating factor 5 (IRF5) is a multifunctional regulator of immune responses, and has a key pathogenic function in gut inflammation, but how IRF5 is modulated is still unclear. Having performed a kinase inhibitor library screening in macrophages, here we identify protein-tyrosine kinase 2-beta (PTK2B/PYK2) as a putative IRF5 kinase. PYK2-deficient macrophages display impaired endogenous IRF5 activation, leading to reduction of inflammatory gene expression. Meanwhile, a PYK2 inhibitor, defactinib, has a similar effect on IRF5 activation in vitro, and induces a transcriptomic signature in macrophages similar to that caused by IRF5 deficiency. Finally, defactinib reduces pro-inflammatory cytokines in human colon biopsies from patients with ulcerative colitis, as well as in a mouse colitis model. Our results thus implicate a function of PYK2 in regulating the inflammatory response in the gut via the IRF5 innate sensing pathway, thereby opening opportunities for related therapeutic interventions for inflammatory bowel diseases and other inflammatory conditions.

Melatonin-Mediated Colonic Microbiota Metabolite Butyrate Prevents Acute Sleep Deprivation-Induced Colitis in Mice

Radical cure colitis is a severe public health threat worldwide. Our previous studies have confirmed that melatonin can effectively improve gut microbiota disorder and mucosal injury caused by sleep deprivation (SD). The present study further explored the mechanism whereby exogenous melatonin prevented SD-induced colitis. 16S rRNA high-throughput sequencing and metabolomics analysis were used to explore the correlation between SD-induced colitis and intestinal microbiota and metabolite composition in mice. Fecal microbiota transplantation (FMT) and melatonin or butyrate supplementation tests verified the core role of gut microbiota in melatonin-alleviating SD-induced colitis. Further, in vitro tests studied the modulatory mechanism of metabolite butyrate. The results demonstrated that SD leads to reductions in plasma melatonin levels and colonic Card9 expression and consequent occurrence of colitis and gut microbiota disorder, especially the downregulation of Faecalibacterium and butyrate levels. The FMT from SD-mice to normal mice could restore SD-like colitis, while butyrate supplementation to SD-mice inhibited the occurrence of colitis, but with no change in the plasma melatonin level in both treatments. However, melatonin supplementation reversed all inductions in SD-mice. In intestinal epithelial cells, the inflammatory ameliorative effect of butyrate was blocked with pretreatments of HDAC3 agonist and HIF-1α antagonist but was mimicked by GSK-3β and p-P65 antagonists. Therefore, the administration of MLT may be a better therapy for SD-induced colitis relative to butyrate. A feasible mechanism would involve that melatonin up-regulated the Faecalibacterium population and production of its metabolite butyrate and MCT1 expression and inhibited HDAC3 in the colon, which would allow p-GSK-3β/β-catenin/HIF-1α activation and NF-κB/NLRP3 suppression to up-regulate Card9 expression and suppress inflammation response.

Anti-colitic effects of the modified Bojanggunbi-tang on dextran sulfate sodium-induced mouse colitis model

Bojanggunbi-tang (BGT) is a well-known and widely used herbal prescription in Korea for colon diseases, with well-documented pharmacological effects on the digestive system. The current study aimed to develop a new simple and effective prescription using the original prescription. mBGT, a modified BGT, was developed by mixing the extracts of Lonicera japonica Thunb., Alisma orientalis and Atractylodes macrocephala based on a literature review and screening of 16 kinds of component herbs of BGT. A colitis mouse (Male, BALB/c) model was induced using dextran sulfate sodium (5%). The effects of BGT and mBGT on body weight, histological damage, clinical score, macroscopic score and colon length were compared. The mechanisms of action were analyzed based on cytokine production in colon tissue. mBGT at 300mg/kg showed similar effectiveness to that of BGT on colon shortening (P<0.01), clinical score (P<0.05), macroscopic score (P<0.01) and histological damage (P<0.01). In addition, mBGT decreased cytokines, including Interleukin 1 beta, tumor necrosis factor alpha and Interleukin 17, in a dose-dependent manner. In conclusion, mBGT could be a substitute prescription for BGT in clinics and a candidate for the development of a new BGT-based therapeutic agent against colitis.

Matrine protects against DSS-induced murine colitis by improving gut barrier integrity, inhibiting the PPAR-α signaling pathway, and modulating gut microbiota

Matrine is a naturally occurring quinolizidine alkaloid with various bioactivities. However, little is known of its function on ulcerative colitis (UC). Here, we investigated the effect and underlying mechanisms of matrine on dextran sulfate sodium (DSS)-induced UC mice. In this study, different concentrations of matrine were given to mice with DSS-induced colitis for a week. The symptoms of colitis, colonic pathology, inflammation-related indicators, and intestinal mucosal barrier function were detected and analyzed. Moreover, RNA-seq analysis in colon tissues was conducted, and 16S rDNA sequencing was carried out to evaluate the gut microbiota of colon contents. The results showed that matrine significantly alleviated clinical activity and histological changes of UC mice, inhibited the production of the pro-inflammatory cytokines, and improved gut barrier integrity. Moreover, RNA-seq analysis and experimental verification showed that matrine significantly inhibited the peroxisome proliferator-activated receptor-α (PPAR-α) signaling pathway. 16S rDNA sequencing revealed that matrine altered the composition and functions of gut microbiota, increased the abundance of Barnesiella intestinihominis and decreased the abundance of Helicobacter ganmani at the species level. In conclusion, matrine ameliorated DSS-induced colitis by improving gut barrier integrity, inhibiting the PPAR-α signaling pathway, and modulating gut microbiota. These suggested that matrine may be a therapeutic agent for UC treatment.

The Preventive Effect of Lactobacillus plantarum ZS62 on DSS-Induced IBD by Regulating Oxidative Stress and the Immune Response

In this study, we used DSS to establish an IBD mouse model to study the preventive effect of Lactobacillus plantarum (L. plantarum) ZS62 on IBD in the context of oxidative stress and the immune response. We assessed the mitigating effect of this strain on IBD mice by examining the length of and histopathological changes in the colon, determining the serum antioxidant index and the levels of inflammatory cytokines, as well as the mRNA and protein expression levels of relevant genes. The study results showed that L. plantarum ZS62 could inhibit colonic atrophy in IBD mice, reduce the degree of colonic damage, downregulate the serum levels of MDA, MPO, IL-1β, IL-6, IL-12, TNF-α, and IFN-γ and the relative mRNA and protein expression of IL-1β, IL-12, TNF-α, COX-2, iNOS, and NF-κB p65 in mouse colon tissues, and upregulate the serum levels of CAT, T-SOD, and IL-10 and the relative mRNA and protein expression of Cu/Zn SOD, Mn SOD, GSH-Px, CAT, IL-10, and IκB-α in colon tissues. In summary, L. plantarum ZS62 exhibited a good preventive effect on DSS-induced IBD by regulating oxidative stress and the immune response.

Overexpression of Vitamin D Receptor in Intestinal Epithelia Protects Against Colitis via Upregulating Tight Junction Protein Claudin 15

BACKGROUND AND AIMS

Dysfunction of the vitamin D receptor [VDR] contributes to the aetiology of IBD by regulating autophagy, immune response, and mucosal permeability. VDR directly controls the paracellular tight junction protein Claudin-2. Claudin-2 and Claudin-15 are unique in maintaining paracellular permeability. Interestingly, claudin-15 mRNA was downregulated in patients with ulcerative colitis. However, the exact mechanism of Claudin-15 regulation in colitis is still unknown. Here, we investigated the protective role of VDR against intestinal inflammation via upregulating Claudin-15.

METHODS

We analysed the correlation of Claudin-15 with the reduction of VDR in human colitis. We generated intestinal epithelial overexpression of VDR [O-VDR] mice to study the gain of function of VDR in colitis. Intestinal epithelial VDR knockout [VDR∆IEC] mice were used for the loss of function study. Colonoids and SKCO15 cells were used as in vitro models.

RESULTS

Reduced Claudin-15 was significantly correlated with decreased VDR along the colonic epithelium of human IBD. O-VDR mice showed decreased susceptibility to chemically and bacterially induced colitis and marked increased Claudin-15 expression [both mRNA and protein] in the colon. Correspondingly, colonic Claudin-15 was reduced in VDR∆IEC mice, which were susceptible to colitis. Overexpression of intestinal epithelial VDR and vitamin D treatment resulted in a significantly increased Claudin-15. ChIP assays identified the direct binding of VDR to the claudin-15 promoter, suggesting that claudin-15 is a target gene of VDR.

CONCLUSION

We demonstrated the mechanism of VDR upregulation of Claudin-15 to protect against colitis. This might enlighten the mechanism of barrier dysfunction in IBD and potential therapeutic strategies to inhibit inflammation.