Experimental Colitis Model Research Articles

Evaluation of the Effects of Biological Therapy with Infliximab in an Experimental Model of Diversion Colitis

Evaluation of the Effects of Biological Therapy with Infliximab in an Experimental Model of Diversion Colitis

Inflammasome Regulation: Therapeutic Potential for Inflammatory Bowel Disease.

Inflammasomes are multiprotein complexes formed to regulate the maturation of pro-inflammatory caspases, in response to intracellular or extracellular stimulants. Accumulating studies showed that the inflammasomes are implicated in the pathogenesis of inflammatory bowel disease (IBD), although their activation is not a decisive factor for the development of IBD. Inflammasomes and related cytokines play an important role in the maintenance of gut immune homeostasis, while its overactivation might induce excess immune responses and consequently cause tissue damage in the gut. Emerging studies provide evidence that some genetic abnormalities might induce enhanced NLRP3 inflammasome activation and cause colitis. In these cases, the colonic inflammation can be ameliorated by blocking NLRP3 activation or its downstream cytokine IL-1β. A number of natural products were shown to play a role in preventing colon inflammation in various experimental colitis models. On the other hand, lack of inflammasome function also causes intestinal abnormalities. Thus, an appropriate regulation of inflammasomes might be a promising therapeutic strategy for IBD intervention. This review aims at summarizing the main findings in these studies and provide an outline for further studies that might contribute to our understanding of the role of inflammasomes in the pathogenesis and therapeutic treatment of IBD.

Modular immune-homeostatic microparticles promote immune tolerance in mouse autoimmune models.

The therapeutic goal for autoimmune diseases is disease antigen-specific immune tolerance without nonspecific immune suppression. However, it is a challenge to induce antigen-specific immune tolerance in a dysregulated immune system. In this study, we developed immune-homeostatic microparticles (IHMs) that treat multiple mouse models of autoimmunity via induction of apoptosis in activated T cells and reestablishment of regulatory T cells. Specifically, in an experimental model of colitis, IHMs rapidly released monocyte chemotactic protein-1 after intravenous administration, which recruited activated T cells and then induced their apoptosis by conjugated Fas ligand on the IHM surface. This triggered professional macrophages to ingest apoptotic T cells and produce high quantities of transforming growth factor-β, which drove regulatory T cell differentiation. Furthermore, the modular design of IHMs allowed IHMs to be engineered with the autoantigen peptides that can reduce disease in an experimental autoimmune encephalomyelitis mouse model and a nonobese diabetic mouse model. This was accomplished by sustained release of the autoantigens after induction of T cell apoptosis and transforming growth factor-β production by macrophages, which promoted to establish an immune tolerant environment. Thus, IHMs may be an efficient therapeutic strategy for autoimmune diseases through induction of apoptosis and reestablishment of tolerant immune responses.

Deficiency of Dietary Fiber Modulates Gut Microbiota Composition, Neutrophil Recruitment and Worsens Experimental Colitis.

Ulcerative colitis is an inflammatory disease of the colon that is associated with colonic neutrophil accumulation. Recent evidence indicates that diet alters the composition of the gut microbiota and influences host–pathogen interactions. Specifically, bacterial fermentation of dietary fiber produces metabolites called short-chain fatty acids (SCFAs), which have been shown to protect against various inflammatory diseases. However, the effect of fiber deficiency on the key initial steps of inflammation, such as leukocyte–endothelial cell interactions, is unknown. Moreover, the impact of fiber deficiency on neutrophil recruitment under basal conditions and during inflammation in vivo is unknown. Herein, we hypothesized that a fiber-deficient diet promotes an inflammatory state in the colon at baseline and predisposes the host to more severe colitis pathology. Mice fed a no-fiber diet for 14 days showed significant changes in the gut microbiota and exhibited increased neutrophil-endothelial interactions in the colonic microvasculature. Although mice fed a no-fiber diet alone did not have observable colitis-associated symptoms, these animals were highly susceptible to low dose (0.5%) dextran sodium sulphate (DSS)-induced model of colitis. Supplementation of the most abundant SCFA, acetate, prevented no-fiber diet-mediated enrichment of colonic neutrophils and colitis pathology. Therefore, dietary fiber, possibly through the actions of acetate, plays an important role in regulating neutrophil recruitment and host protection against inflammatory colonic damage in an experimental model of colitis.

McN-A-343, a muscarinic agonist, reduces inflammation and oxidative stress in an experimental model of ulcerative colitis

AimThe aim of the present study was to investigate the anti-inflammatory response mediated of the M1 muscarinic acetylcholine receptor (mAChR) during experimental colitis. Material and methodsAfter the induction of 6% acetic acid colitis, mice were treated with McN-A-343 0.5, 1.0, and 1.5 mg/kg or dexamethasone (DEXA, 2.0 mg/kg) or pirenzepine (PIR, 10 mg/kg; M1 mAChR antagonist). Colonic inflammation was assessed by macroscopic and microscopic lesion scores, colonic wet weight, myeloperoxidase (MPO) activity, interleukin-1 beta (IL1-β) levels and tumor necrosis factor alpha (TNF-α), glutathione (GSH), malondialdehyde (MDA) and nitrate and nitrite (NO3/NO2), mRNA expression of IKKα, nuclear factor kappa beta (NF-kB) and cyclooxygenase-2 (COX-2), as well protein expression of NF-kB and COX-2. ResultsTreatment with McN-A-343 at a concentration of 1.5 mg/kg showed a significant reduction in intestinal damage as well as a decrease in wet weight, MPO activity, pro-inflammatory cytokine concentration, markers of oxidative stress and expression of inflammatory mediators. The action of the M1 agonist by the administration of pirenzepine, which promoted the blocking of the mAChR M1-mediated anti-inflammatory response, has also been proven. ConclusionThe results suggest that peripheral colonic M1 mAChR is involved in reversing the pro-inflammatory effect of experimentally induced colitis, which may represent a promising therapeutic alternative for patients with ulcerative colitis.

Effect of Cynara cardunculus L. var. altilis (DC) in Inflammatory Bowel Disease

Background: Cynara cardunculus L. var. altilis (DC) is a plant generally associated as an ingredient in the Mediterranean diet. The polyphenols present in this plant provide pharmacological and nutritional properties. C. cardunculus L. has been used throughout animal studies, which demonstrated an anti-inflammatory effect. Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract. Since there is not a known cure, the research of new possible pharmacological approaches is essential. This study aims to evaluate the effect of an aqueous extract of C. cardunculus L. dry leaves in a 2,4,6-Trinitrobenzenesulfonic acid (TNBS)-induced colitis model. Methods: CD-1 mice with TNBS-induced colitis received an intraperitoneal (IP) administration of C. cardunculus L. once per day for 4 days. Results: The C. cardunculus L. demonstrated a beneficial effect in this experimental model of IBD with anti-inflammatory action through the reduction of tumor necrosis factor (TNF)-α levels. It also demonstrated a beneficial influence on the extra-intestinal manifestations related to IBD, with the absence of significant side effects of its use. Conclusions: The extract of C. cardunculus L. dry leaves can become an interesting tool for new possible pharmacological approaches in the management of IBD.

Antibiotic-associated dysbiosis affects the ability of the gut microbiota to control intestinal inflammation upon fecal microbiota transplantation in experimental colitis models

BackgroundThe gut microbiota plays a central role in host physiology and in several pathological mechanisms in humans. Antibiotics compromise the composition and functions of the gut microbiota inducing long-lasting detrimental effects on the host. Recent studies suggest that the efficacy of different clinical therapies depends on the action of the gut microbiota. Here, we investigated how different antibiotic treatments affect the ability of the gut microbiota to control intestinal inflammation upon fecal microbiota transplantation in an experimental colitis model and in ex vivo experiments with human intestinal biopsies.ResultsMurine fecal donors were pre-treated with different antibiotics, i.e., vancomycin, streptomycin, and metronidazole before FMT administration to colitic animals. The analysis of the gut microbiome, fecal metabolome, and the immunophenotyping of colonic lamina propria immune cells revealed that antibiotic pre-treatment significantly influences the capability of the microbiota to control intestinal inflammation. Streptomycin and vancomycin-treated microbiota failed to control intestinal inflammation and were characterized by the blooming of pathobionts previously associated with IBD as well as with metabolites related to the presence of oxidative stress and metabolism of simple sugars. On the contrary, the metronidazole-treated microbiota retained its ability to control inflammation co-occurring with the enrichment of Lactobacillus and of innate immune responses involving iNKT cells. Furthermore, ex vivo cultures of human intestinal lamina propria mononuclear cells and iNKT cell clones from IBD patients with vancomycin pre-treated sterile fecal water showed a Th1/Th17 skewing in CD4+ T-cell populations; metronidazole, on the other hand, induced the polarization of iNKT cells toward the production of IL10.ConclusionsDiverse antibiotic regimens affect the ability of the gut microbiota to control intestinal inflammation in experimental colitis by altering the microbial community structure and microbiota-derived metabolites.6E6mfZzU_A62fWsXVW3UYFVideo

CCL4-mediated targeting of spleen tyrosine kinase (Syk) inhibitor using nanoparticles alleviates inflammatory bowel disease.

Inflammatory bowel disease (IBD) has emerged a global disease and the ascending incidence and prevalence is accompanied by elevated morbidity, mortality, and substantial healthcare system costs. However, the current typical one‐size‐fits‐all therapeutic approach is suboptimal for a substantial proportion of patients due to the variability in the course of IBD and a considerable number of patients do not have positive response to the clinically approved drugs, so there is still a great, unmet demand for novel alternative therapeutic approaches. Spleen tyrosine kinase (Syk), a cytoplasmic nonreceptor protein tyrosine kinase, plays crucial roles in signal transduction and there are emerging data implicating that Syk participates in pathogenesis of several gut disorders, such as IBD. In this study, we observed the Syk expression in IBD patients and explored the effects of therapeutic Syk inhibition using small‐molecule Syk inhibitor piceatannol in bone marrow–derived macrophages (BMDMs). In addition, due to the poor bioavailability and pharmacokinetics of small‐molecule tyrosine kinase inhibitors and superiority of targeting nanoparticles‐based drug delivery system, we herein prepared piceatannol‐encapsulated poly(lactic‐co‐glycolic acid) nanoparticles that conjugated with chemokine C–C motif ligand 4 (P‐NPs‐C) and studied its therapeutic effects in vitro in BMDMs and in vivo in experimental colitis model. Our results indicated that in addition to alleviating colitis, oral administration of P‐NPs‐C promoted the restoration of intestinal barrier function and improved intestinal microflora dysbiosis, which represents a promising treatment for IBD.

Curcumin improves experimentally induced colitis in mice by regulating follicular helper T cells and follicular regulatory T cells by inhibiting interleukin-21.

To determine whether curcumin (Cur) can treat mice with experimentally-induced colitis by regulating follicular helper T cells (Tfh) and follicular regulatory T cells (Tfr) by inhibiting interleukin (IL)-21. In this study, 40 male C57BL/6 mice were randomly grouped into four groups, i.e., normal, trinitrobenzene sulfonic acid (TNBS), TNBS + curcumin, and TNBS + anti-IL-21. Mice with experimental colitis were induced by 100 mg/kg TNBS. The mice in the TNBS + Cur group were treated with 100 mg/kg curcumin for seven days, and mice in the TNBS + anti-IL-21 group were treated with anti-IL-21 (150 μg/mouse) once per week, intraperitoneally, starting on the second day after establishing the experimental colitis model. On day eight, the therapeutic effect of curcumin was evaluated by colon mucosa damage index (CMDI), histological examination, and disease activity index (DAI). Furthermore, the number of CD4 + CXCR5 + PD-1 + Tfh and CD4 + CXCR5 + FoxP3 + Tfr cells were measured by flow cytometry. The mRNA and protein expression of IL-21, Bcl-6, FOXP3, ICOS, and PD-1 in colonic mucosa was detected by reverse transcription polymerase chain reaction and the Western blot technique. Compared with the TNBS group, the DAI, CMDI, histological score, the number of CD4 + CXCR5 + PD-1 + Tfh cells, the expression of IL-21, Bcl-6, ICOS, and PD-1 were significantly decreased in the TNBS + curcumin group and TNBS + anti-IL-21 group; body weight, number of CD4 + CXCR5 + FoxP3 + Tfr cells, and the expression of FoxP3 were observably elevated in the TNBS + curcumin group (all P < 0.05). Curcumin may have a potential therapeutic effect on mice with colitis treated experimentally through regulation of the balance of Tfh and Tfr cells via inhibiting the synthesis of IL-21.

Ursolic Acid Exhibits Protective Property against DSS-induced Ulcerative Colitis in Mice through STAT3 Signaling Pathway

Objective:Anti-inflammatory effects of ursolic acid(UA)on a dextran sulfate sodium(DSS)-induced experimental murine colitis models was investigated to elucidate its possible molecular mechanisms on intestinal epithelial cells(IEC).Methods:For in vivo study,a total of 15 male BALB/c mice weighing(20-22)g were randomly divided into three groups:normal control group,DSS model group and DSS+UA treatment group;the mouse colitis model was induced by 3%dextran sodium sulfate(DSS)for 8 days;one of the DSS-induced groups was pretreated with UA.The body weight and colon length of mice in each group were measured by physical balance and vernier caliper,respectively.The mice in each group were scored according to the clinical disease activity index(DAI)score method.HE staining was used to observe the histopathological changes of colon in each group.The changes of serum amyloid protease A(SAA)and IL-6 expression in colon tissue were measured by ELISA.Using IL-6-stimulated differentiated Caco-2 cells as an in vitro inflammatory model of human intestinal epithelium,the effects of UA on the activation of IL-6/signal transducer and activator of transcription 3(STAT3)signal pathway in IEC were examined by Western blot for STAT3 phosphorylation.Results:1)Compared with the normal control group,the DAI score was increased,the length of the colon was shortened,and the histological damage was obvious in the DSS model group(P<0.05);administration of UA significantly reduced the severity of DSS-induced murine colitis as assessed by DAI score,colon length,and histology damage of colon(P<0.05).2)Compared with the normal control group,the SAA level and the IL-6 level of colon tissue in the DSS model group increased significantly.The DSS-induced increases of SAA and colonic IL-6 levels were reversed by UA treatment(P<0.05).3)Compared with normal IEC,IL-6 stimulation significantly increased the phosphorylation level of STAT3;STAT3 phosphorylation in IEC-treated with IL-6 and UA was significantly inhibited compared with only IL-6 stimulation(P<0.05).Conclusion:Our findings implicate that UA ameliorates DSS-induced colonic inflammation by blocking IL-6/STAT3 signaling pathway,and therefore indicate that UA may have clinical potential as a novel targeted therapy for ulcerative colitis.

MiR-330 alleviates dextran sodium sulfate-induced ulcerative colitis through targeting IRAK1 in rats.

Ulcerative colitis (UC) is a chronic multifactorial inflammatory bowel disease that severely impairs patients' life quality. microRNAs (miRNAs) have been reported to exhibit potential therapeutic effects in the management of UC. With the aim to investigate the regulatory effects of miR-330 on UC-related colon tissue damage and inflammation, a rat model of experimental colitis was established by oral administration of dextran sodium sulfate (DSS). DSS-treated rats showed mucosal damage, colonic inflammation, and elevated myeloperoxidase activity compared with the healthy controls. Dual-luciferase reporter assay confirmed the binding of interleukin-1 receptor-associated kinase 1 (IRAK1) and miR-330. Subsequently, rats were intracolonically injected with miR-330 argomir with/without administration of IRAK1 during DSS treatment. The miR-330 overexpression reduced DSS-induced colonic injury and the production of proinflammatory cytokines. The level of IRAK1 was negatively regulated by the expression of miR-330. IRAK1 overexpression abolished the protective effect of miR-330 on DSS-induced colonic inflammation and mucosal injury in rats. In conclusion, we clarify the role of miR-330 in pathogenesis of UC, suggesting miR-330 alleviated DSS-induced colitis by downregulating IRAK1, shedding lights on miR-330 as a therapeutic candidate for UC treatment.

Local Stabilization of Hypoxia-Inducible Factor-1α Controls Intestinal Inflammation via Enhanced Gut Barrier Function and Immune Regulation.

Intestinal epithelial cells are adapted in mucosal hypoxia and hypoxia-inducible factors in these cells can fortify barrier integrity to support mucosal tissue healing. Here we investigated whether hypoxia-related pathways could be proposed as potential therapeutic targets for inflammatory bowel disease. We developed a novel hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor, CG-598 which stabilized HIF-1α in the gut tissue. Treatment of CG-598 did not affect extra-intestinal organs or cause any significant adverse effects such as erythropoiesis. In the experimental murine colitis model, CG-598 ameliorated intestinal inflammation with reduction of inflammatory lesions and pro-inflammatory cytokines. CG-598 treatment fortified barrier function by increasing the expression of intestinal trefoil factor, CD73, E-cadherin and mucin. Also, IL-10 and IL-22 were induced from lamina propria CD4+ T-cells. The effectiveness of CG-598 was comparable to other immunosuppressive therapeutics such as TNF-blockers or JAK inhibitors. These results suggest that CG-598 could be a promising therapeutic candidate to treat inflammatory bowel disease.

Galanin receptor 3 attenuates inflammation and influences the gut microbiota in an experimental murine colitis model

The regulatory (neuro)peptide galanin and its three receptors (GAL1–3R) are involved in immunity and inflammation. Galanin alleviated inflammatory bowel disease (IBD) in rats. However, studies on the galanin receptors involved are lacking. We aimed to determine galanin receptor expression in IBD patients and to evaluate if GAL2R and GAL3R contribute to murine colitis. Immunohistochemical analysis revealed that granulocytes in colon specimens of IBD patients (Crohn’s disease and ulcerative colitis) expressed GAL2R and GAL3R but not GAL1R. After colitis induction with 2% dextran sulfate sodium (DSS) for 7 days, mice lacking GAL3R (GAL3R-KO) lost more body weight, exhibited more severe colonic inflammation and aggravated histologic damage, with increased infiltration of neutrophils compared to wild-type animals. Loss of GAL3R resulted in higher local and systemic inflammatory cytokine/chemokine levels. Remarkably, colitis-associated changes to the intestinal microbiota, as assessed by quantitative culture-independent techniques, were most pronounced in GAL3R-KO mice, characterized by elevated numbers of enterobacteria and bifidobacteria. In contrast, GAL2R deletion did not influence the course of colitis. In conclusion, granulocyte GAL2R and GAL3R expression is related to IBD activity in humans, and DSS-induced colitis in mice is strongly affected by GAL3R loss. Consequently, GAL3R poses a novel therapeutic target for IBD.

Vitamin D Deficiency Exacerbates Colonic Inflammation Due to Activation of the Local Renin-Angiotensin System in the Colon.

The renin-angiotensin system (RAS) is activated in inflammatory bowel disease (IBD), and vitamin D deficiency aggravates the development of colitis, but the relationship between the local colonic RAS and vitamin D is unclear with regard to the pathogenesis of IBD. To investigate whether vitamin D suppresses the local colonic RAS to prevent colonic mucosal inflammation in a mouse model of experimental colitis. C57BL/6 mice fed vitamin D-deficient (VDD) diet for 8weeks were induced to colitis by 2,4,6-trinitrobenzenesulfonic acid (TNBS), with mice fed vitamin D-sufficient (VDS) diet as controls. Colitis severity was assessed by histology, and pro-inflammatory cytokines, RAS components, and signaling pathways were quantified by real-time RT-PCR and Western blotting. C57BL/6 mice fed the VDD diet for 8weeks exhibited significantly lower serum 25(OH)D3 concentrations compared to mice fed the VDS diet. When these VDD mice were induced to colitis by TNBS, they exhibited more severe colonic inflammation and developed more severe colitis compared to the VDS counterparts. VDD diet feeding resulted in higher production of mucosal pro-inflammatory cytokines, higher activation of the myosin light chain kinase-tight junction regulatory pathway, and greater increases in mucosal permeability. VDD diet feeding also enhanced colonic RAS activation. Treatment with angiotensin II receptor blocker losartan markedly alleviated colitis in TNBS-induced VDD mice. Vitamin D deficiency promotes colonic inflammation at least in part due to over activation of the local RAS in the colon.

Inhibition of PD-1 Protects against TNBS-Induced Colitis via Alteration of Enteric Microbiota.

Methods Colitis was induced in mice using 2,4,6-trinitrobenzene-sulfonic acid (TNBS), and mice were subsequently treated with either a PD-1 inhibitor or 5-amino-salicylic acid (ASA) as a positive control. Body weight, disease activity index (DAI), colon length, and tissue damage were evaluated, and the enteric microbiota was profiled using high-throughput 16S rRNA sequencing of fecal samples from the experimental mice. Results TNBS caused mice to experience IBD-like symptoms, which were attenuated by the PD-1 inhibitor, as indicated by a decrease in DAI scores (p = 0.0002). Furthermore, in this mouse model of IBD, PD-1 inhibition improved the alpha diversity as well as restored the beta diversity of the enteric microbiome. It also significantly enriched the abundance of short-chain fatty acid- (SCFA-) producing bacteria of the Firmicutes (p < 0.05) and Bacteroidetes (p < 0.05) phyla but depopulated Proteobacteria (p < 0.05). Conclusion PD-1 inhibition can partly mitigate TNBS-induced colitis and restore the enteric microbiota by enriching the abundance of SCFA-producing bacteria.

Enema based therapy using liposomal formulation of low molecular weight heparin for treatment of active ulcerative colitis: New adjunct therapeutic opportunity

Ulcerative colitis (UC) is an idiopathic bowel disease involving chronic inflammation and ulcers in colon and implicates severe epithelial damage with disruption in colon homeostasis. Presently existing treatments possess serious concerns like off target effects and adverse reactions, drug inactivation, poor absorption and other complications resulting in poor bioavailability. In context of high risk of thrombotic events in UC patients, heparin can offer appreciable benefits in UC management due to its remarkable anti-coagulating properties, its ability to intervene inflammatory pathways and acceleration of wound healing process. However, oral administration of heparin being impractical due to harsh gastric acidic environment and heparin degradation, conventional heparin administration is done via intravenous route. Present study was designed to formulate, characterize and evaluate sustained release heparin formulation in mice model of experimental colitis. Heparin liposomes (HLp) were formulated by solvent evaporation and extrusion process and possessed hydrodynamic diameter of 242 ± 4.3 nm. Size, shape and surface morphology was confirmed by TEM, SEM and AFM micrographs while encapsulation efficiency and loading of heparin in optimized HLp were 59.61% and 12.27%, respectively. HLp enema administration ameliorated gross disease indices like body weight, colon length, stool consistency, fecal occult blood. Further, anti-inflammatory efficacy of HLp was established in histopathological analysis where HLp appreciably restored protective mucin layer, colon epithelial mucosal histoarchitecture and considerably attenuated mast cell infiltration in colon epithelia. Overall, results of this study indicate that HLp demonstrated an appreciable therapeutic efficacy in experimental colitis and these results are attributed to their ability to suppress inflammation.

Biological Activity and Therapeutic Potential of Quercetin for Inflammatory Bowel Disease

Rates of inflammatory bowel disease (IBD) are increasing globally. IBD is an idiopathic chronic inflammatory disorder of the gastrointestinal tract characterized by acute disease flares and remission. IBD has a multifactorial pathogenesis whereby environmental and genetic factors contribute to disease onset. IBD is a serious clinical disorder that significantly impairs the patient’s quality of life, and is associated with increased morbidity, mortality, and cancer risk. IBD is characterized by the loss of tolerance to luminal antigens resulting in a persistent and excessive immune response. There is currently an unmet need for novel treatment options for patients with IBD. In recent years, flavonoids, a class of polyphenols widely distributed in fruits and vegetables gained significant interest as potential therapeutic agents for inflammatory disorders including IBD. Many flavonoids regulate cellular transcription factors critical in antioxidant and anti-inflammatory pathways within the innate and adaptive immune response. Among these flavonoids, quercetin and its related glycosides have demonstrated remarkable effects capable of attenuating inflammation in experimental models of IBD. To date, many mechanisms underlying quercetin’s biological activity have been elucidated; wherein quercetin is reported to downregulate NFκB, MAPK, STAT and AP-1, and upregulate Nrf2. Thus, the aim of the review is to present the evidence surrounding quercetins biological activity, and its potential as a novel dietary intervention for IBD.

A Brief Idea about Oral Tolerance Therapy in an Experimental Model of Colitis

Oral tolerance can be characterized from an immunological and clinical perspective. Immunologically, oral resistance is an antigenexplicit concealment of cell and humoral reactions to dietary and bacterial antigens after openness in the gastrointestinal lot. Clinically, oral resistance is the capacity to eat food without growing immunologically intervened side effects regardless of the recurrence and amount of food burned-through. There are various aggregates of oral resistance to food sources. Most food-open minded people don't foster immunoglobulin E refinement to food varieties; be that as it may, some do and a subset of these foster clinical food sensitivity.

Luteolin suppresses 5-hydroxytryptamine elevation in stimulated RBL-2H3 cells and experimental colitis mice.

Increased 5-hydroxytryptamine may be associated with the development and progression of inflammatory bowel disease. In this study, we examined the suppressive effect of flavonoids on the increased intra- and extracellular 5-hydroxytryptamine levels in rat mast RBL-2H3 cells, known to produce 5-hydroxytryptamine by the phorbol 12-myristate 13-acetate stimulation. Among the flavonoids examined, luteolin and quercetin significantly reduced the cellular 5-hydroxytryptamine concentration. Gene and protein expression analyses revealed that luteolin significantly suppressed cellular tryptophan hydroxylase 1 expression induced by phorbol 12-myristate 13-acetate stimulation. Mitogen-activated protein kinase/extracellular signal-regulated kinase signaling was also suppressed by luteolin, suggesting that this pathway is one of targets of 5-hydroxytryptamine modulation by luteolin. An in vivo experimental colitis model was prepared by administering 2.5% dextran sodium sulfate in drinking water to C57BL/6 mice for seven days. The ingestion of 0.1% dietary luteolin suppressed the increasing 5-hydroxytryptamine in the colorectal mucosa. In conclusion, luteolin possesses a suppressive effect on extensive 5-hydroxytryptamine formation in both experimental RBL-2H3 cells and colitis models.

Elevation of the serotonin-derived quinone, tryptamine-4,5-dione, in the intestine of ICR mice with dextran sulfate-induced colitis.

Inflammatory bowel diseases, including Crohn’s disease and ulcerative colitis, are chronic inflammatory disorders associated with oxidative stress. The intestines produce 5-hydroxytryptamine that may negatively affect disease state under inflammatory conditions when overproduced. 5-Hydroxytryptamine is a substrate for myeloperoxidase and is converted into reactive tryptamine-4,5-dione. Here, an experimental colitis model was established through oral administration of 5% dextran sulfate sodium to ICR mice for 7 days. Furthermore, the formation of tryptamine-4,5-dione in the colorectal mucosa/submucosa and colorectal tissue was analyzed by chemical and immunochemical methodologies. First, free tryptamine-4,5-dione in the homogenate was chemically trapped by o-phenylenediamine and analyzed as the stable phenazine derivative. Tryptamine-4,5-dione localization as adducted proteins in the colorectal tissue was immunohistochemically confirmed, and as demonstrated by both methods, this resulted in the significant increase of tryptamine-4,5-dione in dextran sulfate sodium-challenged mice compared with control mice. Immunohistochemical staining confirmed tryptamine-4,5-dione-positive staining at the myeloperoxidase accumulation site in dextran sulfate sodium-challenged mice colorectal tissue. The tryptamine-4,5-dione locus in the mice was partly matched with that of a specific marker for myeloperoxidase, halogenated tyrosine. Overall, the results possibly indicate that tryptamine-4,5-dione is generated by neutrophil myeloperoxidase in inflammatory tissue and may contribute to the development of inflammatory bowel disease.