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Increased sugar intake and taste dysfunction have been reported in patients with inflammatory bowel disease (IBD), a chronic disorder characterized by diarrhea, pain, weight loss and fatigue. It was previously unknown whether taste function changes in mouse models of IBD. Mice consumed dextran sodium sulfate (DSS) during three 7-day cycles to induce chronic colitis. DSS-treated mice displayed signs of disease, including significant weight loss, diarrhea, loss of colon architecture, and inflammation of the colon. After the last DSS cycle we assessed taste function by recording electrophysiological responses from the chorda tympani (CT) nerve, which transmits activity from lingual taste buds to the brain. DSS treatment significantly reduced neural taste responses to natural and artificial sweeteners. Responses to carbohydrate, salt, sour or bitter tastants were unaffected in mice with colitis, but umami responses were modestly elevated. DSS treatment modulated the expression of receptor subunits that transduce sweet and umami stimuli in oral taste buds as a substrate for functional changes. Dysregulated systemic cytokine responses, or dysbiosis that occurs during chronic colitis may be upstream from changes in oral taste buds. We demonstrate for the first time that colitis alters taste input to the brain, which could exacerbate malnutrition in IBD patients.

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Dietary intervention in the treatment of ulcerative colitis involves, among other things, modifications in fatty acid content and/or profile. For example, replacing saturated long chain fatty acids with medium chain fatty acids (MCFAs) has been reported to ameliorate inflammation. The Black Soldier Fly Larvae's (BSFL) oil is considered a sustainable dietary ingredient rich in the MCFA C12:0; however, its effect on inflammatory-related conditions has not been studied until now. Thus, the present study aimed to investigate the anti-inflammatory activity of BSFL oil in comparison to C12:0 using TLR4- or TLR2-activated THP-1 and J774A.1 cell lines and to assess its putative protective effect against dextran sulfate sodium (DSS)-induced acute colitis in mice. BSFL oil and C12:0 suppressed proinflammatory cytokines release in LPS-stimulated macrophages; however, only BSFL oil exerted anti-inflammatory activity in Pam3CSK4-stimulated macrophages. Transcriptome analysis provided insight into the possible role of BSFL oil in immunometabolism switch, involving mTOR signaling and an increase in PPAR target genes promoting fatty acid oxidation, exhibiting a discrepant mode of action compared to C12:0 treatment, which mainly affected cholesterol biosynthesis pathways. Additionally, we identified anti-inflammatory eicosanoids, oxylipins, and isoprenoids in the BSFL oil that may contribute to an orchestrated anti-inflammatory response. In vivo, a BSFL oil-enriched diet (20%) ameliorated the clinical signs of colitis, as indicated by improved body weight recovery, reduced colon shortening, reduced splenomegaly, and an earlier phase of secretory IgA response. These results indicate the novel beneficial use of BSFL oil as a modulator of inflammation.

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Inflammatory bowel disease (IBD) is a chronic inflammatory disease, and the incidence of IBD is increasing every year owing to changes in dietary structure. Although the exact pathogenesis of IBD is still unclear, recent evidence suggests that gut dysbiosis is closely associated with IBD pathogenesis. Cheonggukjang is a traditional Korean fermented soybean paste produced using traditional and industrial methods, and contains probiotics, which affect the gut microbiota composition. However, the protective effect of Cheonggukjang against IBD is unknown. In this study, we investigated the bacterial community structure of traditional and commercial Cheonggukjang samples, as well as the protective effect of Cheonggukjang on a dextran sulfate sodium (DSS)-induced colitis mouse model. Traditional and commercial Cheonggukjang were found to contain various type of useful probiotics in their bacterial community structure. Cheonggukjang reduced the progression of DSS-induced symptoms, such as body weight loss, colonic shortening, disease activity index, and histological changes. Further, Cheonggukjang improved the intestinal epithelial barrier integrity on DSS-induced colitis mice. In addition, Cheonggukjang suppressed the expression of proinflammatory cytokines and inflammatory mediators through the inactivation of NF-κB and MAPK signaling pathways. These results indicate that Cheonggukjang exerts protective effects against DSS-induced colitis, suggesting its possible application as a functional food for improving inflammatory diseases.

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Drugs and therapies available for the treatment of inflammatory bowel disease (IBD) are not satisfactory. Our previous study has established the inhibitor of apoptosis-stimulating p53 protein (iASPP) as an oncogenic regulator in colorectal cancer by forming a regulatory axis or feedback loop with miR-124, p53, or p63. As iASPP could target and inhibit nuclear factor kappa B (NF-κB) activation, in this study the role and mechanism of iASPP in IBD was investigated. The aberrant up-regulation of iASPP in IBD was subsequently confirmed, based on online data sets, clinical sample examinations and 2,4,6-trinitrobenzene sulfonic acid (TNBS)- and dextran sulfate sodium (DSS)-induced colitis mice models. TNBS or DSS stimulation successfully induced colon shortness, body weight loss, mice colon oxidative stress and inflammation. In both types of colitis mice models, iASPP over-expression improved, whereas iASPP knockdown aggravated TNBS or DSS stimulation-caused colon shortness, body weight loss and mice colon oxidative stress and inflammation. Meanwhile, in both types of colitis mice models, iASPP over-expression inhibited p65 phosphorylation and decreased the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-6, C-X-C motif chemokine ligand (CXCL)1 and CXCL2 in mice colons, whereas iASPP knockdown exerted opposite effects.

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Adenosine is a purine nucleoside, resulting from the degradation of adenosine triphosphate (ATP). Under adverse conditions, including hypoxia, ischemia, inflammation, or cancer, the extracellular levels of adenosine increase significantly. Once released, adenosine activates cellular signaling pathways through the engagement of the four known G-protein-coupled receptors, adenosine A1 receptor subtype (A1), A2A, A2B, and A3. These receptors, expressed virtually on all immune cells, mitigate all aspects of immune/inflammatory responses. These immunosuppressive effects contribute to blunt the exuberant inflammatory responses, shielding cells, and tissues from an excessive immune response and immune-mediated damage. However, a prolonged persistence of increased adenosine concentrations can be deleterious, participating in the creation of an immunosuppressed niche, ideal for neoplasia onset and development. Based on this evidence, the present review has been conceived to provide a comprehensive and critical overview of the involvement of adenosine system in shaping the molecular mechanisms underlying the enteric chronic inflammation and in promoting the generation of an immunosuppressive niche useful for the colorectal tumorigenesis.

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Dextran sulfate sodium (DSS)-induced colitis is the most commonly used animal model for inflammatory bowel diseases. However, the precise molecular action of DSS, in particular its initial effect on the epithelial tissue permeability, is still poorly understood. In the present work, organ culture of mouse - and pig colon explants were performed for 1-2 h in the presence/absence of 2% DSS together with polar- and lipophilic fluorescent probes. Probe permeability was subsequently assessed by fluorescence microscopy. DSS rapidly increased paracellular permeability of 70-kDa dextran without otherwise affecting the overall epithelial integrity. FITC-conjugated DSS likewise permeated the epithelial barrier and strongly accumulated in nuclei of cells scattered in the lamina propria. By immunolabeling, plasma cells, T cells, macrophages, mast cells, and fibroblasts were identified as possible targets for DSS, indicating that accumulation of the polyanion in nuclei was not confined to a particular type of cell in the lamina propria. In contrast, colonocytes were rarely targeted by DSS, but as visualized by transmission electron microscopy, it induced the formation of vacuole-like structures in the intercellular space between adjacent epithelial cells. Nuclei of various cell types in the lamina propria, including both cells of the innate and adaptive immune system, are novel targets for a rapid action of DSS, and from previous in vitro studies, polyanions like DSS are known to disrupt nucleosomes by binding to the histones. We therefore propose that nuclear targeting is one way whereby DSS exerts its inflammatory action as a colitogen in animal models of inflammatory bowel diseases.

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The prostaglandin D2 metabolite, 15-deoxy-Δ12,14-Prostaglandin J2 (15d-PGJ2), exerts an anti-inflammatory effect through peroxisome proliferator-activated receptor γ (PPARγ)-dependent and -independent anti-inflammatory actions. In the present study, we focused on heme oxygenase-1 (HO-1) induced by 15d-PGJ2, and evaluated the effects of enema treatment with 15d-PGJ2 in the development of intestinal inflammation using a murine colitis model. Acute colitis was induced with dextran sulfate sodium (DSS) in male C57BL/6 mice (8 weeks old) and NF-E2-related factor-2 (Nrf2) deficient mice. Mice were rectally administered 15d-PGJ2 (1 µM, 0.2 mL: 66.9 ng) daily during DSS administration. Intestinal expression of HO-1 mRNA and protein after rectal administration of 15d-PGJ2 was evaluated by real-time PCR and western blotting, respectively. A disease activity index (DAI) was determined on a daily basis for each animal, and consisted of a calculated score based on changes in body weight, stool consistency, and intestinal bleeding. Tissue-associated myeloperoxidase (MPO) activity as an index of neutrophil infiltration and mRNA expression levels of TNF-α, IFN-γ, and IL-17A were measured in the colonic mucosa. In addition, we evaluated the effects of co-treatment with a HO-1 inhibitor, zinc protoporphyrin IX (ZnPP), or a specific PPARγ antagonist, GW9662. As a result, rectal administration of 15d-PGJ2 markedly induced HO-1 protein and mRNA expression in the colonic mucosa. Treatment with 15d-PGJ2 ameliorated the increase in DAI score and MPO activity and the mRNA expression levels of TNF-α, IFN-γ, and IL-17A after DSS administration. These effects of 15d-PGJ2 against intestinal inflammation were negated by co-treatment with ZnPP, but not with GW9662. In Nrf2 deficient mice, the rectal administration of 15d-PGJ2 did not affect colonic HO-1 expression and activity of DSS-induced colitis. These results demonstrate that 15d-PGJ2 inhibits development of intestinal inflammation in mice via PPAR-independent and Nrf2-HO-1-dependent mechanisms.

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BACKGROUND AND AIMS: Peroxiredoxin 4 (PRDX4), a secretory protein that is preferentially retained in the endoplasmic reticulum (ER), is encoded by a gene located on the X chromosome and highly expressed in colonic tissue. In this study, we investigated the role of PRDX4 by means of male PRDX4-knockout (PRDX4-/y) mice in the development of intestinal inflammation using a dextran sulfate sodium (DSS)-induced colitis model. MATERIALS AND METHODS: Acute colitis was induced with DSS (2.5% in drinking water) in wild-type (WT) and PRDX4-/y male C57BL/6 mice. Histological and biochemical analyses were performed on the colonic tissues. RESULTS: PRDX4 was mainly localized in the colonic epithelial cells in WT mice. The disease activity index (DAI) scores of PRDX4-/y mice were significantly higher compared to those of WT mice. Specifically, PRDX4-/y mice showed marked body weight loss and shortening of colon length compared to WT mice, whereas the myeloperoxidase levels were increased in PRDX4-/y compared to WT mice. In addition, the mRNA expression levels of TNF-α and IFN-γ were significantly higher in the colonic mucosa of PRDX4-/y compared to WT mice. Moreover, the levels of CHOP and activated caspase 3 were higher in the colonic tissues of PRDX4-/y compared to WT mice following treatment with DSS. The ER also showed greater expansion in PRDX4-/y than WT mice, which was consistent with severe ER stress under PRDX4 deficiency. CONCLUSION: Our results demonstrated that the lack of PRDX4 aggravated the colonic mucosal damage induced by DSS. Because PRDX4 functions as an ER thiol oxidase as well as an antioxidant, DSS induced oxidative damage and ER stress to a greater degree in PRDX4-/y than WT mice. These findings suggest that PRDX4 may represent a novel therapeutic molecule in intestinal inflammation.

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Monoterpenoid perillaldehyde (PA) is the major component in Perilla frutescens leaf essential oil, but its function regarding anti-inflammatory effect is unclear. We explored the anti-inflammatory activity of PA in a dextran sulfate sodium (DSS)-induced colitis mouse model using relief of bodyweight loss (avg. 49.2% mitigation; P = 0.094) and colon damage (avg. 35.3% mitigation; P < 0.05) by administration of PA at a 100 mg/kg dosage. The PA administration resulted in suppression of DSS-induced expression of pro-inflammatory cytokine genes and matrix metalloproteinase-9 in the colon (e.g., avg. 60.6% mitigation for TNF-α mRNA levels; P < 0.05). These effects were confirmed in macrophage RAW264.7 cells stimulated with lipopolysaccharide (LPS). Application of PA induced cell suppression of LPS-induced expressions of genes and proteins of pro-inflammatory cytokines and induced activation of c-Jun N-terminal kinases (JNKs, p54 and p46; P < 0.05) but not nuclear factor-κB p65. The half maximal inhibitory concentration for decreased expression levels of TNF-α mRNA was 171.7 µM. We discuss the in vivo function of PA in amelioration of intestinal inflammation via JNK-mediated cytokine regulation.

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Mesenchymal stem cells (MSCs) have been used experimentally for treating inflammatory disorders, partly owing to their immunosuppressive properties. The goal of the study was to determine whether TLR ligands can enhance the therapeutic efficacy of bone marrow-derived MSCs for the treatment of inflammatory bowel disease. Mice (C57BL6) were administered with 4% dextran sulfate sodium (DSS) in drinking water for 7 days and injected with MSCs on days 1 and 3 following DSS ingestion. Our results demonstrated that among various TLR ligands, MSCs treated with polyinosinic-polycytidylic acid [poly(I:C)], which is a TLR3 ligand, more profoundly induced IDO, which is a therapeutically relevant immunosuppressive factor, without any observable phenotype change in vitro. The poly(I:C)-treated MSCs attenuated the pathologic severity of DSS-induced murine colitis when injected i.p. but not i.v. In summary, preconditioning MSCs with poly(I:C) might improve their efficacy in treating DSS-induced colitis, and this effect at least partly depends on the enhancement of their immunosuppressive activity through increasing their production of IDO.

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(Trans)-3,7-Dimethyl-2,6-octadien-1-ol, commonly called geraniol (Ge-OH), is an acyclic monoterpene alcohol with well-known anti-inflammatory, antitumoral, and antimicrobial properties. It is widely used as a preservative in the food industry and as an antimicrobial agent in animal farming. The present study investigated the role of Ge-OH as an anti-inflammatory and anti-dysbiotic agent in the dextran sulfate sodium (DSS)-induced colitis mouse model. Ge-OH was orally administered to C57BL/6 mice at daily doses of 30 and 120 mg kg((-1)) body weight, starting 6 days before DSS treatment and ending the day after DSS removal. Furthermore, Ge-OH 120 mg kg((-1)) dose body weight was administered via enema during the acute phase of colitis to facilitate its on-site action. The results show that orally or enema-administered Ge-OH is a powerful antimicrobial agent able to prevent colitis-associated dysbiosis and decrease the inflammatory systemic profile of colitic mice. As a whole, Ge-OH strongly improved the clinical signs of colitis and significantly reduced cyclooxygenase-2 (COX-2) expression in colonocytes and in the gut wall. Ge-OH could be a powerful drug for the treatment of intestinal inflammation and dysbiosis.

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Mesenchymal stem cells (MSCs) have been used experimentally for treating inflammatory disorders, partly owing to their immunosuppressive properties. The goal of the study was to determine whether TLR ligands can enhance the therapeutic efficacy of bone marrow-derived MSCs for the treatment of inflammatory bowel disease. Mice (C57BL6) were administered with 4% dextran sulfate sodium (DSS) in drinking water for 7 days and injected with MSCs on days 1 and 3 following DSS ingestion. Our results demonstrated that among various TLR ligands, MSCs treated with polyinosinic-polycytidylic acid [poly(I:C)], which is a TLR3 ligand, more profoundly induced IDO, which is a therapeutically relevant immunosuppressive factor, without any observable phenotype change in vitro. The poly(I:C)-treated MSCs attenuated the pathologic severity of DSS-induced murine colitis when injected i.p. but not i.v. In summary, preconditioning MSCs with poly(I:C) might improve their efficacy in treating DSS-induced colitis, and this effect at least partly depends on the enhancement of their immunosuppressive activity through increasing their production of IDO.

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