Effect of low molecular weight heparin rectal suppository on experimental ulcerative colitis in mice

Low-molecular-weight heparin ameliorates intestinal barrier dysfunction in aged male rats via protection of tight junction proteins

The intestinal barrier weakens and chronic gut inflammation occurs in old age, causing age-related illnesses. Recent research shows that low-molecular-weight heparin (LMWH), besides anticoagulation, also has anti-inflammatory and anti-apoptotic effects, protecting the intestinal barrier. This study aims to analyze the effect of LMWH on the intestinal barrier of old male rodents. This study assigned Sprague-Dawley male rats to four groups: young (3 months), young + LMWH, old (20 months), and old + LMWH. The LMWH groups received 1 mg/kg LMWH via subcutaneous injection for 7 days. Optical and transmission electron microscopy (TEM) were used to examine morphological changes in intestinal mucosa due to aging. Intestinal permeability was measured using fluorescein isothiocyanate (FITC)-dextran. ELISA kits were used to measure serum levels of IL-6 and IL-1β, while Quantitative RT-PCR detected their mRNA levels in intestinal tissues. Western blotting and immunohistochemistry (IHC) evaluated the tight junction (TJ) protein levels such as occludin, zonula occludens-1 (ZO-1), and claudin-2. Western blotting assessed the expression of the apoptosis marker cleaved caspase 3, while IHC was used to detect LGR5+ intestinal stem cells. The intestinal permeability of aged rats was significantly higher than that of young rats, indicating significant differences. With age, the protein levels of occludin and ZO-1 decreased significantly, while the level of claudin-2 increased significantly. Meanwhile, our study found that the levels of IL-1β and IL-6 increased significantly with age. LMWH intervention effectively alleviated age-related intestinal barrier dysfunction. In aged rats treated with LMWH, the expression of occludin and ZO-1 proteins in the intestine increased, while the expression of claudin-2 decreased. Furthermore, LMWH administration in aged rats resulted in a decrease in IL-1β and IL-6 levels. LMWH also reduced age-related cleaved caspase3 expression, but IHC showed no difference in LGR5+ intestinal stem cells between groups. Research suggests that LMWH could potentially be a favorable therapeutic choice for age-related diseases associated with intestinal barrier dysfunction, by protecting TJ proteins, reducing inflammation, and apoptosis.

Simultaneous Treatment of 5-Aminosalicylic Acid and Treadmill Exercise More Effectively Improves Ulcerative Colitis in Mice

Ulcerative colitis (UC) is characterized by continuous mucosal ulceration of the colon, starting in the rectum. 5-Aminosalicylic acid (5-ASA) is the main therapy for ulcerative colitis; however, it has side effects. Physical exercise effectively increases the number of anti-inflammatory and anti-immune cells in the body. In the current study, the effects of simultaneous treatment of treadmill exercise and 5-ASA were compared with monotherapy with physical exercise or 5-ASA in UC mice. To induce the UC animal model, the mice consumed 2% dextran sulfate sodium dissolved in drinking water for 7 days. The mice in the exercise groups exercised on a treadmill for 1 h once a day for 14 days after UC induction. The 5-ASA-treated groups received 5-ASA by enema injection using a 200 μL polyethylene catheter once a day for 14 days. Simultaneous treatment improved histological damage and increased body weight, colon weight, and colon length, whereas the disease activity index score and collagen deposition were decreased. Simultaneous treatment with treadmill exercise and 5-ASA suppressed pro-inflammatory cytokines and apoptosis following UC. The benefits of this simultaneous treatment may be due to inhibition on nuclear factor-κB/mitogen-activated protein kinase signaling activation. Based on this study, simultaneous treatment of treadmill exercise and 5-ASA can be considered as a new therapy of UC.

(-)-Syringaresinol attenuates ulcerative colitis by improving intestinal epithelial barrier function and inhibiting inflammatory responses

BACKGROUND

(-)-Syringaresinol (SYR), a natural lignan with significant antioxidant and anti-inflammatory activities, possesses various pharmacological benefits including cardio-protective, antibacterial, anticancer, and anti-aging effects. It was shown that the effectiveness of (+)-syringaresinol diglucoside on the ulcerative colitis (UC) was attributed to the active metabolite (+)-syringaresinol (the enantiomor of SYR). However, the efficacy of SYR against UC remains unclear, and the associated molecular mechanism has not been revealed yet PURPOSE: This study aimed to assess the protective effect of SYR in UC and its underlying mechanism STUDY DESIGN AND METHODS: We examined SYR's protective impact on the intestinal epithelial barrier and its ability to inhibit inflammatory responses in both a lipopolysaccharide (LPS)-induced Caco-2 cell model and a dextran sodium sulfate (DSS)-induced UC mouse model. We also explored the potential signaling pathways regulated by SYR using transcriptome analysis and western blot assay RESULTS: In Caco-2 cells, SYR significantly increased trans-epithelial electrical resistance, reduced tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interferon-γ (IFN-γ), and cyclooxygenase-2 (COX-2) levels, and enhanced cellular tight junction protein expression and distribution. In mice with UC, oral treatment with SYR (10, 20, 40 mg·kg-1) dose-dependently increased body weight, colon length, and expression of tight junction proteins, decreased disease activity index score, spleen coefficient, cytokine serum levels, bacterial translocation, and intestinal damage, and also preserved the ultrastructure of colonic mucosal cells. Transcriptomics indicated that the anti-UC effect of SYR is mediated via the PI3K-Akt/MAPK/Wnt signaling pathway.

CONCLUSION

In summary, SYR effectively mitigated the development of UC by enhancing the intestinal epithelial barrier function and attenuating the inflammatory response. The plant-derived product SYR might be a potentially effective therapeutical agent against UC.

Effects of photobiomodulation in the experimental acetic acid-induced colitis: comparison between male and female

Ulcerative colitis (UC) is an important chronic and multifactorial disease, which alters the colon mucosal with a significant impact on life quality affecting both men and women. The difference between genders causes changes in the inflammatory processes, modulating the development of several diseases. The available drugs to treat UC exhibit limited outcomes and side effects; thus, new therapies are needed. Photobiomodulation (PBM) emerges as potential treatment by modulating the inflammatory process without side effects and low costs. The aim of this study was to evaluate the effects of PBM in acetic acid-induced UC comparing the responses between male and females. For this purpose, male and female Wistar rats (36) were submitted to induction of UC by rectal administration of 10% acetic acid (colitis group) and treated or not with PBM (colitis-PBM group) (LED, 660 nm, 100 mW, 150 s) in three points: right side and left of the ventral surface and in the external anal region. Non-manipulated rats were used as control (basal group). We investigated the disease activity index (DAI score), myeloperoxidase enzyme activity (MPO) and release of cytokines in the intestine homogenates, and histological analysis. PBM reduces DAI score, MPO activity, and mast cell degranulation while increased mucous production in both females and males. Moreover, PBM reduced histopathological score as well as the levels of IL-6 and IL-4 in the bowel only in males. We also showed reduced levels of IL-1beta and TNF-alpha after PBM in both males and females, while the levels of IL-10 and IFN-gamma were increased. In conclusion, despite our study has shown some differences between males and females, PBM attenuated the biomarkers of UC in both genders constituting a potential combined treatment that is non-invasive and low cost.

Study on the Comprehensive Phytochemicals and the Anti-Ulcerative Colitis Effect of Saussurea pulchella

BACKGROUND

Saussurea pulchella (SP) is a traditional medicinal plant that is widely used in folk medicine because of its diverse biological activities, particularly its anti-inflammatory effects. However, the alleviation effect of SP on ulcerative colitis (UC) has not yet been realized.

PURPOSE

To investigate the chemical composition and therapeutic effect of SP extract against UC.

METHODS

First, qualitative and quantitative analysis of SP 75% ethanol extract was performed by UPLC-Q/TOF-MS. Second, a dextran sodium sulfate (DSS) model of UC mice was developed to study the effects of SP on the symptoms, inflammatory factors, oxidative stress indexes and colon histopathology. Third, an integration of network pharmacology with metabolomics was performed to investigate the key metabolites, biological targets and metabolisms closely related to the effect of SP.

RESULTS

From the SP ethanol extract, 149 compounds were identified qualitatively and 20 were determined quantitatively. The SP could dose-dependently decrease the DAI score, spleen coefficient and the levels of TNF-α, IL-6, iNOS, MPO and MDA; increase the colon length, GSH level and SOD activity; and protect the intestinal barrier in the UC mice. Moreover, 10 metabolite biomarkers,18 targets and 5 metabolisms were found to play crucial roles in the treatment of UC with SP.

CONCLUSIONS

SP 75% ethanol extract could effectively alleviate the progression of UC and, therefore, could be classified as a novel natural treatment for UC.

Dental pulp stem cells overexpressing hepatocyte growth factor facilitate the repair of DSS-induced ulcerative colitis

Background

Ulcerative colitis (UC) is a chronic and recurrent disease without satisfactory treatment strategies. Dental pulp stem cell (DPSC) transplantation has been proposed as a potential therapy for UC. This study aimed to investigate the therapeutic effects of the rat hepatocyte growth factor (HGF) gene transduced into DPSCs for UC.

Methods

The therapeutic effects of HGF-DPSCs transplanted intravenously into a rat model of UC induced by 5% dextran sulphate sodium (DSS) were compared with the other treatment groups (LV-HGF group, DPSCs group and GFP-DPSCs group). Immunofluorescence and immunohistochemistry were used to observe the localization and proliferation of HGF-DPSCs at the site of colon injury. The expression levels of inflammatory factors were detected by real-time quantitative PCR (RT-PCR) and western blotting. The oxidative stress markers were detected by ELISA. DAI scores and body weight changes were used to macroscopically evaluate the treatment of rats in each group.

Results

Immunofluorescence and immunohistochemistry assays showed that HGF-DPSCs homed to colon injury sites and colocalized with intestinal stem cell (ISC) markers (Bmi1, Musashi1 and Sox9) and significantly promoted protein expression (Bmi1, Musashi1, Sox9 and PCNA). Anti-inflammatory cytokine (TGF-β and IL-10) expression was the highest in the HGF-DPSCs group compared with the other treatment groups, while the expression of pro-inflammatory cytokines (TNF-α and INF-γ) was the lowest. Additionally, the oxidative stress response results showed that malondialdehyde (MDA) and myeloperoxidase (MPO) expression decreased while superoxide dismutase (SOD) expression increased, especially in the HGF-DPSCs group. The DAI scores showed a downward trend with time in the five treatment groups, whereas body weight increased, and the changes were most prominent in the HGF-DPSCs group.

Conclusions

The study indicated that HGF-DPSCs can alleviate injuries to the intestinal mucosa by transdifferentiating into ISC-like cells, promoting ISC-like cell proliferation, suppressing inflammatory responses and reducing oxidative stress damage, which provides new ideas for the clinical treatment of UC.

The Role of Glycosaminoglycans in Protection from Neonatal Necrotizing Enterocolitis: A Narrative Review

Necrotizing enterocolitis, a potentially fatal intestinal inflammatory disorder affecting primarily premature infants, is a significant cause of morbidity and mortality in neonates. While the etiology of the disease is, as yet, unknown, a number of risk factors for the development of necrotizing enterocolitis have been identified. One such risk factor, formula feeding, has been shown to contribute to both increased incidence and severity of the disease. The protective influences afforded by breastfeeding are likely attributable to the unique composition of human milk, an extremely potent, biologically active fluid. This review brings together knowledge on the pathogenesis of necrotizing enterocolitis and current thinking on the instrumental role of one of the more prominent classes of bioactive components in human breast milk, glycosaminoglycans.

Nanoparticle-based delivery enhances anti-inflammatory effect of low molecular weight heparin in experimental ulcerative colitis

Epithelial administration of low molecular weight heparin (LMWH) has proven its therapeutic efficiency in ulcerative colitis (UC) but still lacks of a sufficiently selective drug delivery system. Polymeric nanoparticles were used here not only to protect LMWH from intestinal degradation but also to provide targeted delivery to inflamed tissue in experimental colitis mice. LMWH was associated with polymethacrylate nanoparticles (NP) type A (PEMT-A) or type B (PEMT-B) of a size: 150 nm resulting in a maximum drug loading: 0.1 mg/mg. In a lipopolysaccharide-stimulated macrophages both, free LMWH and LMWH-NP have significantly reduced the cytokines secretion independently from cellular uptake. The in-vivo therapeutic efficiency was dose dependent as at low doses (100 IU/kg) only minor differences between free LMWH and LMWH-NP were found and the superiority of LMWH-NP became prominent with dose increase (500 IU/kg). Administration of LMWH-NP at 500 IU/kg has markedly improved the clinical activity as compared to LMWH while similarly pathophysiological indicators revealed increased therapeutic outcome in presence of NP compared to LMWH alone: Myeloperoxidase (Colitis control: 10 480 ± 5335, LMWH-PEMT-A NP: 1507 ± 2165, LMWH-PEMT-B NP: 382 ± 143, LMWH: 8549 ± 5021 units/g) and tumor necrosis factor: (Colitis control: 1636 ± 544, LMWH-PEMT-A NP: 511 ± 506, LMWH-PEMT-B NP: 435 ± 473, LMWH: 1110 ± 309 pg/g). Associating LMWH with NP is improving the anti-inflammatory efficiency of LMWH in-vivo by its protection against degradation in luminal environment and selective drug delivery. Such a combination holds promise for a highly specific therapy by its double selectivity towards the inflamed intestinal tissue. LMWH-PEMT NP have significantly improved the clinical activity in-vivo in comparison to free LMWH.

Animal models of ulcerative colitis developed with chemicals

In recent years, the incidence of ulcerative colitis (UC) has been rising obviously with the changes in people's diet (e.g., high fat diet), and it has become a common digestive system disease as well as a main cause of chronic diarrhea. Patients usually suffer from great pain because of the delayed recovery and repeated attacks of UC, and some of the patients may develop into colon cancer. At present, the pathogenesis of UC is not fully clear, anti-inflammatory drugs are mostly used clinically for the treatment of UC, but their efficacy is not satisfying. Therefore, it is of great significance to further investigate the etiology, mechanisms and new treatment strategies for UC using effective animal models of UC. There are many methods to establish animal models of UC. The present review mainly focuses on the mechanisms, characteristics and applications of UC animal models established using chemical substances.

Unfractionated or low-molecular weight heparin for induction of remission in ulcerative colitis

BACKGROUND

There are a limited number of treatment options for patients with ulcerative colitis (UC). An increased risk of thrombosis in UC coupled with an observation that UC patients being treated with anticoagulant therapy for thrombotic events had an improvement in their bowel symptoms led to trials examining the use of unfractionated heparin (UFH) and low molecular weight heparins (LMWH) in patients with active UC.

OBJECTIVES

To review randomized trials examining the efficacy of unfractionated heparin (UFH) or low molecular weight heparins (LMWH) for remission induction in patients with ulcerative colitis.

SEARCH METHODS

We searched MEDLINE, EMBASE, CENTRAL, and the Cochrane IBD/FBD group specialized trials register up to June 2014. We also searched review papers on ulcerative colitis and references from identified papers in an effort to identify additional randomized trials studying UFH or LMWH use in patients with ulcerative colitis. We searched abstracts from major gastroenterological meetings to identify research published in abstract form.

SELECTION CRITERIA

Randomized controlled trials comparing UFH or LMWH to placebo or a control therapy for induction of remission in ulcerative colitis were included. Studies published in abstract form only were included if the authors could be contacted for further information.

DATA COLLECTION AND ANALYSIS

A data extraction form was developed and used to extract data from included studies. Two authors independently extracted data. Any disagreements were resolved by consensus. The Cochrane Risk of Bias tool was used to assess study quality. Data were analyzed on an intention-to-treat basis. The primary outcome was induction of remission, as defined by the studies. Secondary outcomes measures included: endoscopic remission as defined by the authors; clinical, histological or endoscopic improvement as defined by the authors; the occurrence of adverse events; the occurrence of bleeding; and improvements in quality of life as measured by a validated instrument. We calculated the risk ratio (RR) and corresponding 95% confidence interval for dichotomous outcomes. Data were combined for analysis if they assessed the same treatments (UFH or LMWH versus placebo or other therapy). The overall quality of the evidence supporting the outcomes was evaluated using the GRADE criteria.

MAIN RESULTS

Five studies were eligible for inclusion (329 patients). Three studies (270 patients) compared low molecular weight heparin to placebo, one study (34 patients) compared LMWH in addition to standard therapy, and one study (25 patients) compared UFH to corticosteroids. The study comparing UFH to corticosteroids was rated at high risk of bias due to a single-blind design. The study that compared the addition of LMWH to standard therapy to standard therapy alone was rated at high risk of bias due to open-label design. The other three studies were rated as low risk of bias. LMWH administered subcutaneously showed no benefit over placebo for any outcome, including clinical remission (very low quality of evidence), and clinical, endoscopic, or histological improvement. High dose LMWH administered via an extended colon-release tablet demonstrated benefit over placebo for clinical remission (RR 1.39; 95% CI 1.09 to 1.77 ; P = 0.008; very low quality of evidence), clinical improvement (RR 1.28; 95% CI 1.06 to 1.55; P = 0.01; very low quality of evidence), and endoscopic improvement (RR 1.21; 95% CI 1.00 to 1.47 ; P = 0.05) but not endoscopic remission or histologic improvement. LMWH was not beneficial when added to standard therapy for clinical remission, clinical improvement, endoscopic remission or endoscopic improvement. LMWH was well-tolerated but provided no significant benefit for quality of life. One study examining UFH versus corticosteroids for the treatment of severe UC demonstrated the inferiority of UFH for clinical improvement. More patients assigned to UFH had rectal hemorrhage as an adverse event.

AUTHORS' CONCLUSIONS

There is evidence to suggest that LMWH may be effective for the treatment of active UC. When administered by extended colon-release tablets, LMWH was more effective than placebo for treating outpatients with mild to moderate disease. This benefit needs to be confirmed by further randomized controlled studies. The same benefits were not seen when LMWH was administered subcutaneously at lower doses. There is no evidence to support the use of UFH for the treatment of active UC. A further trial of UFH in patients with mild disease may also be justified. Any benefit found would need to be weighed against a possible increased risk of rectal bleeding in patients with active UC.

Protective effect of cavidine on acetic acid-induced murine colitis via regulating antioxidant, cytokine profile and NF-κB signal transduction pathways

Ulcerative colitis is an inflammatory disorder characterized by neutrophils infiltration, oxidative stress, upregulation of pro-inflammatory mediators and cytokines. Cavidine possesses anti-inflammatory activity and has been used to treat various inflammatory diseases but its effect on ulcerative colitis has not been previously explored. The present study aims to evaluate the effect of cavidine on acetic acid-induced ulcerative colitis in mice. Colitis mice induced by intra-rectal acetic acid (5%, v/v) administration received cavidine (1, 5 and 10mg/kg, i.g) or sulfasalazine (500mg/kg, i.g) for seven consecutive days. After euthanized by cervical dislocation, colonic segments of mice were excised for clinical, macroscopic, biochemical and histopathological examinations. Results suggested treatment with cavidine significantly decreased mortality rate, body weight loss, disease activity index (DAI), wet colon weight, macroscopic and histological score when compared with that of acetic acid-induced controls. In addition, administration of cavidine effectively modulated expressions of MPO, GSH, SOD and MDA. Furthermore cavidine inhibited the level of TNF-α and IL-6 in the serum and colon tissue in response to the regulation of p65 NF-κB protein expression. All these results indicated cavidine exerts marked protective effect in experimental colitis, possibly by regulating the expression of oxygen metabolites, NF-κB and subsequent pro-inflammatory cytokines production.

Ascidian (chordate-tunicate) and mammalian heparin enemas attenuate experimental diversion colitis

AIM

We sought to investigate whether mammalian or ascidian Styela plicata heparin enemas could diminish inflammation in experimental diversion colitis.

METHODS

Wistar-specific pathogen-free rats were submitted to a Hartmann's end colostomy and treated with enemas containing mammalian or Styela plicata heparin, or saline. Enemas were administered 3 times a week in the excluded colon segment from 4 to 8 weeks after operation. The effect of treatment was evaluated using video-endoscopic and histologic scores, measuring the cytokines interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and transforming growth factor-β production in organ cultures by enzyme-linked immunosorbent assay, quantifying T cells and macrophages, and investigating nuclear factor-kappa B (NF-κB) and external mitogen-activated protein kinase (pERK) activation.

RESULTS

Treatment with either mammalian or Styela plicata heparins decreased colonoscopic and histologic scores (P < .02) and restored the densities of collagen fibers and the number of goblet cells (P < .03) in the diverted colon. Both heparin treatments decreased the accumulation of T cells and macrophages (P < .03), and the activation of NF-κB and pERK (P < .04) in the diverted colon. The high levels of cytokines IL-1β, TNF-α, and IL-6 from the diversion colitis explants decreased (P < .05) to near normal values with heparin treatments.

CONCLUSION

The improvement of experimental diversion colitis with heparin treatments indicates the anti-inflammatory effect of these compounds, even after topical administration. Further studies with the nonhemorrhagic heparin obtained from the invertebrate Styela plicata will be necessary to confirm its efficacy for the treatment of human diversion colitis and possibly other forms of colitis.

Animal models of ulcerative colitis

Ulcerative colitis (UC) is a chronic, recurrent inflammatory disease of the colon, characterized clinically by bloody diarrhea and abdominal pain. UC has been a clinical challenge due to its increasing incidence and prevalence, unknown etiology and pathogenesis, and the lack of effective treatment. Animal models have been widely used to investigate the pathogenesis of various diseases. So far, many animal models of UC have been developed, which play a crucial role in studying the pathogenesis of UC and finding new potential treatments. This article reviews the recent progress in the development of animal models of UC.

Quercetin-loaded microcapsules ameliorate experimental colitis in mice by anti-inflammatory and antioxidant mechanisms

Quercetin (1) is an anti-inflammatory and antioxidant flavonoid. However, the oral administration of 1 did not lead to beneficial effects in experimental animal colitis models, which involve cytokines and oxidative stress. A possible explanation is that the absorption profile of 1 prevents its activity. Therefore, it was reasoned that the controlled release of 1 would improve its therapeutic effect. Thus, the therapeutic effect and mechanisms of 1-loaded microcapsules in acetic acid-induced colitis in mice were evaluated. Microcapsules were prepared using pectin/casein polymer and 1. The oral administration of 1-loaded microcapsules decreased neutrophil recruitment, attenuated histological alterations, and reduced macroscopical damage, edema, and IL-1β and IL-33 production in the colon samples. Microcapsules loaded with 1 also prevented the reduction of anti-inflammatory cytokine IL-10 and the antioxidant capacity of the colon. These preclinical data indicate that pectin/casein polymer microcapsules loaded with 1 improved the anti-inflammatory and antioxidant effects of 1 compared to the nonencapsulated drug. Therefore, quercetin seems to be a promising active molecule in inflammatory bowel disease if provided with adequate controlled release.

Protective effect of sanguinarine against acetic acid-induced ulcerative colitis in mice

The quaternary ammonium salt, sanguinarine (SANG), is of great practical and research interest because of its pronounced, widespread physiological effects, which promote anti-microbial and anti-inflammatory responses in experimental animals. Although SANG is originally shown to possess anti-inflammatory properties and it has been used to treat various inflammatory diseases, its effects on ulcerative colitis have not been previously explored. The aim of the present study is to evaluate the effect of SANG on acetic acid-induced ulcerative colitis in mice. Experimental animals received SANG (1, 5 and 10 mg/kg, p.o.) and sulfasalazine (500 mg/kg, p.o.) for seven consecutive days after induction of colitis by intra-rectal acetic acid (5% v/v) administration. The colonic mucosal injury was assessed by clinical, macroscopic, biochemical and histopathological examinations. SANG treatment significantly decreased mortality rate, body weight loss, disease activity index (DAI), wet colon weight, macroscopic and histological score when compared to acetic acid-induced controls. In addition, administration of SANG effectively inhibited p65 NF-κB protein expression and MPO activity accumulation. The levels of TNF-α and IL-6 in the serum and colon tissue of mice with experimental colitis were decreased by SANG in a concentration-dependent manner in response to p65 NF-κB. The possible mechanism of protection on experimental colitis was that SANG could be through attenuating early steps of inflammation as well as decreasing the expression of NF-κB and subsequent pro-inflammatory cytokines production.

The effect of methylsulfonylmethane on the experimental colitis in the rat

Methylsulfonylmethane (MSM), naturally occurring in green plants, fruits and vegetables, has been shown to exert anti-inflammatory and antioxidant effects. MSM is an organosulfur compound and a normal oxidative metabolite of dimethyl sulfoxide. This study was carried out to investigate the effect of MSM in a rat model of experimental colitis. Colitis was induced by intracolonic instillation of 1 ml of 5% of acetic acid. Rats were treated with MSM (400 mg/kg/day, orally) for 4 days. Animals were euthanized and distal colon evaluated histologically and biochemically. Tissue samples were used to measurement of malondialdehyde (MDA), myeloperoxidase (MPO), catalase (CAT), glutathione (GSH) and proinflammatory cytokine (TNF-α and IL-1β) levels. Results showed that MSM decreased macroscopic and microscopic colonic damage scores caused by administration of acetic acid. MSM treatment also significantly reduced colonic levels of MDA, MPO and IL-1β, while increased the levels of GSH and CAT compared with acetic acid-induced colitis group. It seems that MSM as a natural product may have a protective effect in an experimental ulcerative colitis.