Effect of mild moxibustion on intestinal microbiota and NLRP6 inflammasome signaling in rats with post-inflammatory irritable bowel syndrome.

BACKGROUND: About one-third of refractory irritable bowel syndrome (IBS) cases are caused by gastrointestinal (GI) infection/inflammation, known as post-infectious/post-inflammatory IBS (PI-IBS). Although it is known that intestinal microbiota and host NOD-like receptor family pyrin domain containing 6 (NLRP6) inflammsome signaling are closely related to PI-IBS and moxibustion has a therapeutic effect on PI-IBS, whether moxibustion regulates the intestinal flora and host NLRP6 events in PI-IBS remains unclear. AIM: To examine the regulatory effect of moxibustion on intestinal microbiota and host NLRP6 inflammatory signaling in PI-IBS. METHODS: Sprague-Dawley rats were divided into a normal control group, a model control group, a mild moxibustion group, and a sham mild moxibustion group. PI-IBS rats in the mild moxibustion group were treated with moxibusiton at bilateral Tianshu (ST 25) and Zusanli (ST36) for 7 consecutive days for 10 min each time. The sham group rats were given the same treatment as the mild moxibustion group except the moxa stick was not ignited. Abdominal withdrawal reflex (AWR) score was measured to assess the visceral sensitivity, and colon histopathology and ultrastructure, colonic myeloperoxidase (MPO) activity, and serum C-reactive protein (CRP) level were measured to evaluate low-grade colonic inflammation in rats. The relative abundance of selected intestinal bacteria in rat feces was detected by 16S rDNA PCR and the NLRP6 inflammsome signaling in the colon was detected by immunofluorescence, qRT-PCR, and Western blot. RESULTS: The AWR score was significantly decreased and the low-grade intestinal inflammation reflected by serum CRP and colonic MPO levels was inhibited in the mild moxibustion group compared with the sham group. Mild moxibustion remarkably increased the relative DNA abundances of Lactobacillus, Bifidobacterium, and Faecalibacterium prausnitzii but decreased that of Escherichia coli in the gut of PI-IBS rats. Additionally, mild moxibustion induced mRNA and protein expression of intestine lectin 1 but inhibited the expression of IL-1ß, IL-18, and resistance-like molecule ß by promoting the NLRP6 and reducing the mRNA and protein expression of apoptosis-associated speck-like protein containing CARD (ASC) and cysteinyl-aspartate-specific proteinase 1 (Caspase-1). The relative DNA abundances of Lactobacillus, Bifidobacteria, Faecalibacterium prausnitzii, and Escherichia coli in each group were correlated with the mRNA and protein expression of NLRP6, ASC, and Caspase-1 in the colon. CONCLUSION: These findings indicated that mild moxibustion can relieve low-grade GI inflammation and alleviate visceral hypersensitivity in PI-IBS by regulating intestinal microbes and controlling NLRP6 inflammasome signaling.

Electroacupuncture Alleviated Referral Hindpaw Hyperalgesia via Suppressing Spinal Long-Term Potentiation (LTP) in TNBS-Induced Colitis Rats.

Although referred pain or hypersensitivity has been repeatedly reported in irritable bowel syndrome (IBS) patients and experimental colitis rodents, little is known about the neural mechanisms. Spinal long-term potentiation (LTP) of nociceptive synaptic transmission plays a critical role in the development of somatic hyperalgesia in chronic pain conditions. Herein, we sought to determine whether spinal LTP contributes to the referral hyperalgesia in colitis rats and particularly whether electroacupuncture (EA) is effective to alleviate somatic hyperalgesia via suppressing spinal LTP. Rats in the colitis group (induced by colonic infusion of 2,4,6-trinitrobenzenesulfonic acid, TNBS), instead of the control and vehicle groups, displayed evident focal inflammatory destruction of the distal colon accompanied not only with the sensitized visceromotor response (VMR) to noxious colorectal distension (CRD) but also with referral hindpaw hyperalgesia indicated by reduced mechanical and thermal withdrawal latencies. EA at Zusanli (ST36) and Shangjuxu (ST37) attenuated the severity of colonic inflammation, as well as the visceral hypersensitivity and referral hindpaw hyperalgesia in colitis rats. Intriguingly, the threshold of C-fiber-evoked field potentials (CFEFP) was significantly reduced and the spinal LTP was exaggerated in the colitis group, both of which were restored by EA treatment. Taken together, visceral hypersensitivity and referral hindpaw hyperalgesia coexist in TNBS-induced colitis rats, which might be attributed to the enhanced LTP of nociceptive synaptic transmission in the spinal dorsal horn. EA at ST36 and ST37 could relieve visceral hypersensitivity and, in particular, attenuate referral hindpaw hyperalgesia by suppressing the enhanced spinal LTP.

NaV1.1 inhibition can reduce visceral hypersensitivity.

Functional bowel disorder patients can suffer from chronic abdominal pain, likely due to visceral hypersensitivity to mechanical stimuli. As there is only a limited understanding of the basis of chronic visceral hypersensitivity (CVH), drug-based management strategies are ill defined, vary considerably, and include NSAIDs, opioids, and even anticonvulsants. We previously reported that the 1.1 subtype of the voltage-gated sodium (NaV; NaV1.1) channel family regulates the excitability of sensory nerve fibers that transmit a mechanical pain message to the spinal cord. Herein, we investigated whether this channel subtype also underlies the abdominal pain that occurs with CVH. We demonstrate that NaV1.1 is functionally upregulated under CVH conditions and that inhibiting channel function reduces mechanical pain in 3 mechanistically distinct mouse models of chronic pain. In particular, we use a small molecule to show that selective NaV1.1 inhibition (a) decreases sodium currents in colon-innervating dorsal root ganglion neurons, (b) reduces colonic nociceptor mechanical responses, and (c) normalizes the enhanced visceromotor response to distension observed in 2 mouse models of irritable bowel syndrome. These results provide support for a relationship between NaV1.1 and chronic abdominal pain associated with functional bowel disorders.

Induction of murine TNBS colitis is strictly controlled by a modified method using continuous inhalation anesthesia with sevoflurane.

BACKGROUND: Trinitrobenzenesulfonic acid (TNBS)-induced colitis is one of the most widely used experimental colitis models. However, there is no standard procedure for inducing colitis by TNBS because it is difficult to achieve a uniform distribution of colitis. We have developed a modified method of murine TNBS-induced colitis that involves inhalation anesthesia with sevoflurane combined with both single and repeated TNBS administrations. AIMS: To compare the usefulness of our newly developed method for inducing murine TNBS-induced colitis with that of conventional intraperitoneal anesthesia. METHODS: TNBS in ethanol was administered to C57BL/6J mice held in an inverted vertical position either under continuous inhalation anesthesia with sevoflurane, in accordance with our newly developed method, or by intraperitoneal injection with 2.5 % avertin, in accordance with the conventional procedure. Body weight change, cytokine profile, and histological findings were examined during the course of colitis. RESULTS: The dispersion of anesthesia time, TNBS retention time, and nadir weight during the course of colitis was decreased using the newly developed method compared with the conventional procedure. Optimization of the modified TNBS-induced colitis, as evidenced by the predominant expression of Th1 and Th17 cytokines on day 7, was attained by the injection of 2.25 mg TNBS in 55 % ethanol. Regulation of the TNBS retention time using inhalation anesthesia with sevoflurane allowed strict control of the disease severity of TNBS-induced colitis. Using the modified method we were also able to develop a chronic TNBS-induced colitis model by repeated TNBS administration without excessive mortality of the mice. CONCLUSIONS: Our modified method for murine TNBS-induced colitis using continuous inhalation anesthesia with sevoflurane provides a better experimental colitis model following both single and repeated TNBS administrations.

Role of TRPV1 and TRPA1 in visceral hypersensitivity to colorectal distension during experimental colitis in rats.

The aim of the present study is to investigate the effects of TRPV1 and TRPA1 receptor antagonists and their synergism on the visceromotor responses during experimental colitis in rats. Colitis was induced in rats by a TNBS/ethanol enema at day 0 and was assessed at day 3 using endoscopy, histology and a myeloperoxidase assay. The visceromotor response to colorectal distension (10-80 mmHg) was evaluated in conscious rats before (control condition) and 3 days after 2,4,6-trinitrobenzene sulfonic acid (TNBS) administration (colitis condition). At day 3, visceromotor responses were assessed before and after treatment with a TRPV1 (BCTC) or TRPA1 (TCS-5861528) receptor antagonist either alone or in combination and either after intraperitoneal or intrathecal administration. Endoscopy, microscopy and myeloperoxidase activity indicated severe colonic tissue damage 3 days after TNBS administration. Colorectal distension-evoked visceromotor responses demonstrated a 2.9-fold increase during acute colitis (day 3) compared to control conditions. Intraperitoneal and intrathecal administration of BCTC or TCS-5861528 partially reversed the colitis-induced increase in visceromotor responses compared to control conditions (P<0.05). Intraperitoneal blockade of TRPA1 plus TRPV1 further decreased the enhanced visceromotor responses at high distension pressures (40-80 mmHg) compared to blockade of either TRPV1 or TRPA1 alone. This synergistic effect was not seen after combined intrathecal blockade of TRPA1 plus TRPV1. The present study demonstrates that in the rat, TRPV1 and TRPA1 play a pivotal role in visceral hypersensitivity at the peripheral and spinal cord level during acute TNBS colitis. Target interaction, however, is presumably mediated via a peripheral site of action.

Chios mastic fractions in experimental colitis: implication of the nuclear factor κB pathway in cultured HT29 cells.

The Pistacia lentiscus tree gives a resinous exudate called Chios mastic (CM) rich in triterpenoids. CM can be fractionated into acidic and neutral fractions (AF and NF, respectively). Oleanolic acid (OA) is a major triterpenic acid in CM with several antioxidant and anti-inflammatory properties. We have recently shown that CM is beneficial in experimental colitis in the form of powder mixture with inulin, as supplied commercially. However, the bioactive fraction or compound of CM is unidentified. Thus, based on the hypothesis that terpenoids exhibit functional activities via distinguishable pathways, we fractionated CM and applied different fractions or individual OA in experimental colitis. Furthermore, we investigated the mechanism underlying this effect in human colon epithelial cells. CM powder mixture (100 mg/kg of body weight) or the respective CM powder mixture components (i.e., inulin, AF, NF, or OA) were individually administered in trinitrobenzene sulfonic acid-treated rats. Colonic damage was assessed microscopically, and levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-8, and intercellular adhesion molecule-1were measured. A model of inflammation in co-cultured human colon epithelial HT29 cells and monocytes/macrophages was established. Lactate dehydrogenase release and levels of TNF-α, IL-8, and nuclear factor-κB (NF-κB) p65 were measured. In vivo, histological amelioration of colitis and significant regulation in inflammation occurred with CM powder mixture, even at the mRNA level. Although no histological improvement was observed, AF and NF reduced levels of inflammatory markers. Inulin was ineffective. In vitro, CM treatment down-regulated IL-8 and NF-κB p65. Neither fractions nor OA was the bioactive component solely. Most probably, the entire CM rather than its individual fractions reduces inflammation via NF-κB regulation.

[Crohn disease in rats induced by different concentrations of trinitrobenzenesulfonic acid and ethanol].

OBJECTIVE: To induce Crohn disease in rats by intraluminal instillations of different concentrations of 2,4,6-trinitrobenzenesulfonic acid (TNBS) and ethanol. METHODS: Crohn disease in rats was induced with enema containing TNBS and 50% ethanol with volume ratio of 2:1 (experimental group 1) or 1:1 (experimental group 2), or solution containing TNBS and anhydrous ethanol with volume ratio of 2:1 (experimental group 3) or 1:1 (experimental group 4). Equivalent volume of normal saline was used to set as the normal saline control, and rats without any treatment were set as the normal control group. The rats were killed at various time points (3, 7, 14 and 21 d) respectively. Colonic inflammation and damage were assessed microscopically and histologically. RESULTS: In the colon of rats in the experimental group 3, discontinuous erosion, ulceration and infiltration of neutrophils occurred after one week; pebble sign and even segmental inflammation appeared on day 14. On day 21, it appeared improvement in the colon tissue and obviously thickened bowel wall, but the inflammation was easily observed under the light microscope. Experimental group 1 was similar to experimental group 3 in appearance of the colon on days 3 and 7; on day 14, colonic inflammation and damage were improved as compared with the experimental group 3, but there were obvious individual differences in histological findings among rats in group 1. In the experimental group 2, the intestinal wall turned to be normal on day 14. In the experimental group 4, there were high mortality and extensive damage of colon tissues, and the pathological characteristics were quite different from Crohn disease in humans. CONCLUSION: The characteristics of the rat model of Crohn disease induced with a enema containing TNBS and anhydrous ethanol with volume ratio of 2:1 are similar to the clinical features of human Crohn disease, including typical pathological characteristics and long duration of inflammation. It may be an ideal experimental model for studying pathogenesis of Crohn disease and for evaluating treatment effects.

The water-soluble extract from cultured medium of Ganoderma lucidum (Reishi) mycelia (Designated as MAK) ameliorates murine colitis induced by trinitrobenzene sulphonic acid.

Ganoderma lucidum Karst is well known as 'Reishi', a traditional food in China and Japan. It contains a polysaccharide component known to induce granulocyte macrophage colony-stimulating factor (GM-CSF) production from murine splenocytes. Moreover, GM-CSF may be a therapeutic agent for Crohn's disease. In this study, we investigated the water-soluble, polysaccharide components of Reishi (designated as MAK) in murine colitis induced by trinitrobenzene sulphonic acid (TNBS). We examined the concentration of GM-CSF in peritoneal macrophage cells (PMs) of C57BL/6 mice during in vitro and in vivo stimulation with MAK. After feeding with chow or MAK for 2 weeks, 2 mg of TNBS/50% ethanol was administered to each mouse. After 3 days of TNBS treatment, intestinal inflammation was evaluated, and mononuclear cells of the mesenteric lymph nodes (MLNs) and colon were cultured for ELISA. To determine the preventive role of GM-CSF, the mice were pre-treated with or without anti-GM-CSF antibody before TNBS administration. In vitro and in vivo MAK-stimulated PMs produced GM-CSF in a dose-dependent manner. Intestinal inflammation by TNBS was improved by feeding with MAK. MLNs of mice treated with TNBS produced IFN-γ, which was inhibited by feeding with MAK. In contrast, MLNs of mice treated with TNBS inhibited GM-CSF production, which was induced by feeding with MAK. The colon organ culture assay also revealed that IFN-γ was decreased and GM-CSF was increased by MAK. The preventive effect was blocked by the neutralization of GM-CSF. We concluded that the induction of GM-CSF by MAK may provide the anti-inflammatory effect.

Involvement of tyrosine kinase-2 in both the IL-12/Th1 and IL-23/Th17 axes in vivo.

Tyrosine kinase-2 (Tyk2), a member of the Jak family of kinases, mediates the signals triggered by various cytokines, including type I IFNs, IL-12, and IL-23. In the current study, we investigated the in vivo involvement of Tyk2 in several IL-12/Th1- and IL-23/Th17-mediated models of experimental diseases, including methylated BSA injection-induced footpad thickness, imiquimod-induced psoriasis-like skin inflammation, and dextran sulfate sodium- or 2,4,6-trinitrobenzene sulfonic acid-induced colitis. In these disease models, Tyk2 deficiency influenced the phenotypes in immunity and/or inflammation. Our findings demonstrate a somewhat broader contribution of Tyk2 to immune systems than previously expected and suggest that Tyk2 may represent an important candidate for drug development by targeting both the IL-12/Th1 and IL-23/Th17 axes.

Immunomodulatory and therapeutic potential of a mycelial lectin from Aspergillus nidulans.

Lectins bind to surface receptors on target cells, and activate a cascade of events, eventually leading to altered immune status of host. The immunomodulatory potential of purified lectin from Aspergillus nidulans was evaluated in Swiss albino mice treated intraperitoneally with seven different doses of purified lectin. Lectin prevented BSA-induced Arthus reaction and systemic anaphylaxis. The enhanced functional ability of macrophages was evident from respiratory burst activity and nitric oxide production in splenocyte cultures. Interferon-gamma and interleukin-6 levels were significantly up-regulated in treated groups. Maximum stimulatory effect was observed at the dose of 1.5 mg/kg body weight. Therapeutic potential of A. nidulans lectin was assessed against trinitrobenzene sulfonic acid-induced ulcerative colitis in male Wistar rats. Rats pre-treated with 80 mg/kg body weight of purified lectin intraperitoneally prior to colitis induction showed lesser disease severity and recovery within 7 days, while rats post-treated with the same dose showed recovery in 11 days. The results demonstrate immunomodulatory effects of A. nidulans lectin in Swiss albino mice, resulting in improved immune status of the animals and unfold its curative effect against ulcerative colitis in rat model. This is the first report on immunomodulatory and therapeutic potential of a lectin from microfungi.

An α-linolenic acid-rich formula reduces oxidative stress and inflammation by regulating NF-κB in rats with TNBS-induced colitis.

We have previously shown that α-linolenic acid (ALA), a (n-3) PUFA exerts in vitro antiinflammatory effects in the intestine. In this study, we aimed to evaluate its effect on inflammatory and oxidative stress in a colitis model. Colitis was induced in 2 groups at d 0 by intrarectal injection of 2-4-6-trinitrobenzen sulfonic acid (TNBS), whereas the control group received the vehicle. Rats we fed 450 mg . kg(-1) . d(-1) of ALA (TNBS+ALA) while the other colitic group (TNBS) and the control group were fed an isocaloric corn oil formula for 14 d (from d -7 to d 7). RBC fatty acid composition was assessed. Oxidative stress was studied by measuring urinary 8-isoprostanes (8-IP) and colon glutathione (GSH) concentration and inducible nitric oxide synthase (iNOS) expression. Colitis was assessed histologically, by production of proinflammatory mediators, including cytokines, leukotrienes B(4) (LTB(4)), and cyclooxygenase-2 (COX-2) and by nuclear factor-κB (NF-κB) activation. The ALA-rich diet significantly increased the RBC levels of ALA, eicosapentaenoic acid, and docosapentaenoic acid (n-3) compared with the TNBS group (P < 0.01 for all). The beneficial effect of ALA supplementation on oxidative stress was reflected by lower urinary 8-IP levels (P < 0.05), a normalized colon GSH concentration (P < 0.01), and reduced colon iNOS expression (P < 0.05) compared with the TNBS group. ALA also protected against colon inflammation as assessed by lower tumor necrosis factor-α secretion and mRNA level (P < 0.05), reduced NF-κB activation (P = 0.01), and lower colon lipid mediator concentrations such as LTB(4) and COX-2 (P < 0.05) compared with the TNBS group. These findings show that an ALA-rich formula is beneficial to TNBS-induced colitic rats via inhibition of oxidative and inflammatory stress.

Grifola frondosa water extract alleviates intestinal inflammation by suppressing TNF-alpha production and its signaling

TNF-alpha is a major cytokine involved in inflammatory bowel disease (IBD). In this study, water extract of Grifola frondosa (GFW) was evaluated for its protective effects against colon inflammation through the modulation of TNF-alpha action. In coculture of HT-29 human colon cancer cells with U937 human monocytic cells, TNF-alpha-induced monocyte adhesion to HT-29 cells was significantly suppressed by GFW (10, 50, 100 microg/ml). The reduced adhesion by GFW correlated with the suppressed expression of MCP-1 and IL-8, the major IBD-associated chemokines. In addition, treatment with GFW significantly suppressed TNF-alpha-induced reactive oxygen species production and NF-kappaB transcriptional activity in HT-29 cells. In differentiated U937 monocytic cells, LPS-induced TNF-alpha production, which is known to be mediated through NF-kappaB activation, was significantly suppressed by GFW. In an in vivo rat model of IBD, oral administration of GFW for 5 days (1 g/kg per day) significantly inhibited the trinitrobenzene sulfonic acid (TNBS)-induced weight loss, colon ulceration, myeloperoxidase activity, and TNF-alpha expression in the colon tissue. Moreover, the effect of GFW was similar to that of intra-peritoneal injection of 5-aminosalicylic acid (5-ASA), an active metabolite of sulfasalazine, commonly used drug for the treatment of IBD. The results suggest that GFW ameliorates colon inflammation by suppressing production of TNF-alpha as well as its signaling through NF-kappaB leading to the expression of inflammatory chemokines, MCP-1 and IL-8. Taken together, the results strongly suggest GFW is a valuable medicinal food for IBD treatment, and thus may be used as an alternative medicine for IBD.

Si-Ni-San, a traditional Chinese prescription, and its active ingredient glycyrrhizin ameliorate experimental colitis through regulating cytokine balance.

Si-Ni-San, a traditional Chinese medicinal formula, exerts an important function in the treatment of inflammatory bowel diseases based upon thousands of years of clinical practice, but the underlying mechanism is still unclear. In this study, we investigated the therapeutic potential of Si-Ni-San and its ingredient glycyrrhizin in trinitrobenzene sulfonic acid (TNBS)-induced experimental colitis in mice, a well-characterized murine model for Crohn's disease. Si-Ni-San and glycyrrhizin significantly ameliorated TNBS-induced colitis with reduced mortality and recovery of body weights. In addition, Si-Ni-San and glycyrrhizin dose-dependently decreased macroscopic inflammation scores, microscopic histological scores, and myeloperoxidase activity. Furthermore, Si-Ni-San and glycyrrhizin caused a decrease in pro-inflammatory cytokines including IFN-gamma, IL-12, TNF-alpha and IL-17 and an increase in regulatory cytokine IL-10 in colon of the mice. It should be noticed the therapeutic effect of Si-Ni-San at 450 mg/kg was much better than that of its contained content of glycyrrhizin at 10 mg/kg. In conclusion, Si-Ni-San and glycyrrhizin significantly ameliorated TNBS-induced colitis in mice through regulating pro- and anti-inflammatory cytokine production.

Changes in urinary bladder smooth muscle function in response to colonic inflammation.

Visceral organ "cross talk" is suspected to contribute to multiorgan symptomatology found in conditions such as irritable bowel syndrome and interstitial cystitis. The goal of the present study was to investigate the short- and long-term effects of acute colitis on bladder detrusor muscle contractility. We hypothesized that inflammation of the colon leads to changes in bladder function via direct changes in detrusor smooth muscle contractility. In this study, colonic inflammation was induced in male rats via an enema of trinitrobenzenesulfonic acid (TNBS) (50 mg/kg, 0.5 ml, 25% ethanol). Colitis was confirmed using gross morphology, histology, and measurements of myeloperoxidase activity. Saline enema-treated rats served as controls. Three, 15, and 30 days postenema treatment, bladder detrusor muscle contractility was investigated in response to electrical field stimulation (EFS), cholinergic agonism with carbachol (CCh), and KCl. During active colonic inflammation (day 3 post-TNBS enema), the bladder detrusor muscle appeared normal and showed no significant inflammation. However, abnormalities in bladder detrusor muscle contractility occurred in response to EFS and CCh but not KCl. During and after recovery from colonic inflammation (days 15 and 30 post-TNBS enema), changes in bladder detrusor muscle contractility in response to EFS and CCh returned to control levels. We found that a transient colonic inflammatory insult significantly attenuates the amplitude of bladder detrusor muscle contractions in vitro, at least in part, through changes in cholinergic innervation, which are reversible after recovery from the colitis.

Curcumin inhibits trinitrobenzene sulphonic acid-induced colitis in rats by activation of peroxisome proliferator-activated receptor gamma.

Curcumin is a widely used spice with anti-inflammatory and anti-cancer properties. It has been reported that curcumin held therapeutic effects on experimental colitis by inhibition of nuclear factor kappa B (NF-kappaB). The peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor with anti-tumor and anti-inflammatory effects and its activation may inhibit the nuclear translocation of NF-kappaB. Several studies have shown that PPARgamma ligands had an important therapeutic effect in colitis. However there is no report about the alteration of PPARgamma in trinitrobenzene sulphonic acid (TNBS)-induced colitis treated with curcumin. In this study, we administered curcumin (30 mg/kg/day) by intraperitoneal injection immediately after colitis was induced and the injection lasted for two weeks. have evaluated the effects of curcumin on the colitis induced by trinitrobenzene sulphonic acid (TNBS). Curcumin (30 mg/kg d) was administered by intraperitoneal just after colitis was induced and lasted for two weeks. Therapeutic effects of dexamethasone (Dex, 2 mg/kg d) alone and the combined effects of curcumin+Dex were also examined. We found that curcumin improved long-term survival rate of disease-bearing rats, promoted rat body weight recovery, and decreased macroscopic scores of the colitis. The expression levels of PPARgamma, 15-deoxy-D12,14-prostaglandin J(2) (15d-PGJ(2)) and prostaglandin E(2) (PGE(2)) were all increased, but the expression level of cyclooxygenase-2 (COX-2) was decreased in rats after administration of curcumin. Treatment with Dex improved PPARgamma expression and inhibited the expression of COX-2, 15d-PGJ(2) and PGE(2). Combined effects of curcumin+Dex were similar to that of Dex. In summary, curcumin showed therapeutic effects on TNBS-induced colitis and the mechanisms by which curcumin exerts its effects may involve activation of PPARgamma and its ligands.

Colon epithelial cellular protein induces oral tolerance in the experimental model of colitis by trinitrobenzene sulfonic acid.

Rectal administration of trinitrobenzene sulfonic acid (TNBS) produces chronic colitis in experimental animals. However, the role of epithelial cellular protein(s) in this model is unknown. We examined whether oral tolerance can be induced in this model with colon epithelial cell proteins and whether it is organ specific. Rats were fed five times with extracts of LS-180 human colon cancer cells or HT 1080 human fibroblast cells. Syngeneic normal rat colon or small intestinal extracts were fed to separate groups of rats. After oral feedings, each rat received TNBS by enema. Rats were killed 15 days later, and the following were measured: gross and histologic disease score, weight, thickness, and myeloperoxidase values of colon and serum interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta) levels. Rectal TNBS alone produced severe colitis with a 26% mortality rate. Rats fed LS-180 or rat colon extract before TNBS enema were protected, as evidenced by reductions in mortality rate, disease scores, and myeloperoxidase values. However, rats fed HT 1080 or small intestine extract lacked such protection. To examine the possible mechanism of the oral tolerance, T lymphocytes from mesenteric lymph nodes and spleen of LS-180 extract-fed rats were passively transferred to naive rats, and this was followed by TNBS enema. These rats showed clear protection. Protected animals had low IFN-gamma and high TGF-beta levels. This study demonstrates that cellular protein(s) from human colon epithelial cells, but not from human fibroblasts, can induce oral tolerance in experimental colitis. This oral tolerance is mediated by primed mesenteric and splenic T lymphocytes.

Role of P-selectin and intercellular adhesion molecule-1 in TNB-induced colitis in rats.

It has been proposed that neutrophil-endothelial cell interactions mediated by adhesion molecules are involved in the pathogenesis of inflammatory bowel disease. The objective of the present study was to determine the effects of monoclonal antibodies (MAbs) directed against endothelial adhesion molecules, P-selectin and intercellular adhesion molecule-1 (ICAM-1), in rats with colitis induced by 2,4,6-trinitrobenzene sulfonic acid (TNB). Colonic inflammation was induced by administering an enema of TNB dissolved in 50% ethanol (120 mg/ml) to male Wistar rats (at a total volume of 0.25 ml per rat) after a 48-hour fast. Anti-P-selectin MAb or anti-ICAM-1 MAb was injected via the tail vein at a dose of 1 mg/kg after the induction of colitis. Rats in the control group received nonbinding mouse immunoglobulin G1. The plasma level of soluble P-selectin showed an increase within 48 h after the TNB enema. Colonic inflammation was assessed at 1 week after TNB administration. The colonic damage score and the wet weight of the colon were significantly decreased by treatment with either MAb. The increase of myeloperoxidase (MPO) activity, an index of neutrophil accumulation, and the increase of thiobarbituric acid-reactive substances (TBA-RS), an index of lipid peroxidation, in the colonic mucosa were inhibited by both MAbs. These results suggest that neutrophil-endothelial cell interactions via P-selectin and ICAM-1 play an important role in the development of TNB-induced colitis in rats.

Protective role of cyclooxygenase inhibitors in the adverse action of passive cigarette smoking on the initiation of experimental colitis in rats.

Clinical and experimental findings had indicated that cigarette smoke exposure, and cyclooxygenase-2, are strongly associated with inflammatory bowel disease. The present study aimed to evaluate the role of cyclooxygenase-2 in the pathogenesis of experimental inflammatory bowel disease as well as in the adverse action of cigarette-smoke exposure. Rats were pretreated with different cyclooxygenase-2 inhibitors (indomethacin, nimesulide, or SC-236 (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide)) along with cigarette-smoke exposure before 2,4,6-trinitrobenzenesulfonic acid-enema. Results indicated that pretreatment with cyclooxygenase-2 inhibitors not only protected against 2,4,6-trinitrobenzenesulfonic acid-induced inflammatory bowel disease, but also attenuated the potentiating effect of cigarette-smoke exposure on colonic damage. Furthermore, the colonic cyclooxygenase-2 protein and mRNA expression was markedly induced by 2,4,6-trinitrobenzenesulfonic acid-enema, and it was potentiated further by cigarette-smoke exposure, while the cyclooxygenase-1 expression was not changed. The present study suggests that the highly induced cyclooxygenase-2 expression not only plays a pathogenic role in 2,4,6-trinitrobenzenesulfonic acid-induced inflammatory bowel disease, but also contributes to the adverse action of cigarette-smoke exposure on this disorder.

Mice deficient in Th1- and Th2-type cytokines develop distinct forms of hapten-induced colitis.

BACKGROUND & AIMS: Most experimental models for inflammatory bowel disease in mice are associated with production of interferon (IFN)-gamma and other proinflammatory cytokines. We hypothesized that T-helper 2 (Th2)-type cells could also contribute to the colitis and cause inflammation different than that mediated by Th1-type cells. METHODS: Trinitrobenzene sulfonic acid (TNBS)-induced colitis in C57BL/6 background mice genetically deficient in interleukin (IL)-12 p40 (IL-12(-/-)), IFN-gamma (IFN-gamma(-/-)), or IL-4 (IL-4(-/-)) was examined in comparison with control mice (C57BL/6(+/+)). RESULTS: C57BL/6(+/+), IFN-gamma(-/-), and IL-12(-/-) mice developed patterns of colitis characterized by distortion of crypts, loss of goblet cells, and mononuclear cell infiltration with fibrosis of the mucosal layer. IL-4(-/-) mice had greater mortality than other groups because of penetrating ulcers; however, survivors developed milder lesions that were limited to focal acute ulceration. Colonic CD4(+) T cells from normal, IFN-gamma(-/-), or IL-12(-/- )mice produced both IL-4 and IL-5. CONCLUSIONS: In TNBS colitis, Th1-like cytokine responses induce fatal, acute, transmural, and focal types of lesions, whereas Th2-like cytokine responses play a significant role in the diffuse atrophic changes in crypts and the mucosal layer that occur in the late stages of this disease.

Effect of intrarectal prostaglandin E2 analogue (enprostil) on trinitrobenzenesulphonic acid-induced colitis in rats.

Prostaglandins exert a protective effect on colonic mucosa in experimentally induced colitis. This study investigated the effect of enprostil, a prostaglandin E2 (PGE2) analogue, on trinitrobenzenesulphonic acid (TNBS)-induced colitis in rats. Each rat received a rectal enema containing TNBS (30 mg), followed 24 h later by intrarectal once-daily enprostil (200 microg). Enprostil-treated and control rats were killed on day 3 (enprostil group, n = 5; control, n = 6) or day 10 (enprostil group, n = 5; control, n = 5) after TNBS treatment. The area of damaged mucosa of the colon was measured relative to the total colonic area. We also determined the macroscopic score of mucosal damage, and measured PGE2, 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha) and thromboxane B2 (TXB2) concentration in portal vein blood samples. Enprostil significantly reduced both the area of damaged mucosa (including the ulcer area) and the macroscopic score after 3 days' treatment compared with control. Similarly, enprostil significantly reduced plasma concentration of PGE2, 6-keto-PGF1alpha and TXB2 during the acute phase at day 3 of treatment compared with control, but not at day 10. These results suggest that PGE2 enema may have therapeutic potential for treating patients with proctitis or left-sided colitis.