Chemiluminescence assay of mucosal reactive oxygen metabolites in inflammatory bowel disease.

Previous studies suggesting increased reactive oxygen metabolite (ROM) production in inflammatory bowel disease have been restricted to peripheral blood and isolated intestinal phagocytes. In the current study, chemiluminescence and the effect of various scavengers, enzymes, and enzyme inhibitors were used to show that ROMs account for the increased production of oxidants by colorectal mucosal biopsy specimens in inflammatory bowel disease. Luminol-amplified chemiluminescence was increased in active ulcerative colitis [macroscopic grade 1: 25 photons.mg-1.min.10(-3) (median), 8-47 (95% confidence intervals), n = 40; grade 2: 89, 65-156, n = 30; grade 3: 247, 133-562, n = 13] and Crohn's disease [mild: 9, 3-84, n = 6; severe: 105, 25-789 (range), n = 5] compared with normal-looking mucosa (ulcerative colitis: 0.8, 0.4-1.4, n = 22, P less than 0.01; Crohn's disease: 0.8, 0.1-2, n = 6, P less than 0.05) and controls (0.6, 0.04-1.4, n = 52, P less than 0.01). In ulcerative colitis, luminol chemiluminescence correlated with microscopic inflammation (Spearman's p = 0.74, P = 0.0001) and was decreased by sodium azide (-89%, P less than 0.05), taurine (-31%, P less than 0.05), catalase (-23%, P less than 0.05), and dimethyl sulfoxide (-29%, P less than 0.05). Superoxide dismutase and oxypurinol decreased lucigenin chemiluminescence in ulcerative colitis by -63% (P less than 0.05) and -27% (P less than 0.05), respectively. Luminol chemiluminescence correlated with lucigenin chemiluminescence (Spearman's rho = 0.72, P = 0.003). These results suggest that neutrophil-derived oxidants (superoxide, hydrogen peroxide, hydroxyl radical, and hypochlorite) are generated in colorectal mucosa in active inflammatory bowel disease and support the hypothesis that production of such metabolites by neutrophils is of major pathogenetic importance.     

Role of reactive oxygen metabolites in experimental colitis.

Reactive oxygen metabolites are potent inflammatory mediators that may be involved in tissue injury in inflammatory bowel disease. To evaluate their role in inflammatory bowel disease, we investigated the effects of lowering the activities of reactive oxygen metabolites in experimental colitis induced by intracolonic administration of acetic acid in rats. Intracolonic administration of 5% acetic acid caused severe inflammation (mean (SEM) inflammatory score was 24.3 (0.7) of a maximum score of 32). Acetic acid at 2.5% produced moderate inflammation (score = 17 (1.4) v 4.0 (0.5) in control rats). This lower dose was used for subsequent experiments. Specific superoxide anion scavenger methoxypolyethylene glycol:superoxide dismutase, and reactive oxygen metabolites scavenger, sulfasalazine, significantly decreased the severity of inflammation (scores: 8 (4.4) and 9.8 (2.2) respectively). The xanthine oxidase inhibitors, tungsten and pterin aldehyde, failed to improve inflammation but another xanthine oxidase inhibitor, allopurinol, a compound with known superoxide anion scavenging effect, did limit the inflammation (10(2)). Inhibition of hydroxyl radical production by deferoxamine or lowering hydroxyl radical values by a scavenger, dimethyl sulfoxide, did not affect the severity of inflammation. These data suggest: (1) that reactive oxygen metabolites play an important role in experimental colitis, (2) that the xanthine oxidase pathway is not a major source of reactive oxygen metabolites in colitis, and (3) that tissue injury in experimental colitis is not caused by generation of hydroxyl radicals.     

Clinical implications of oxidative stress and antioxidant therapy

Oxidative stress occurs when there is an imbalance between generation of reactive oxygen species and inadequate antioxidant defense systems. Oxidative stress can cause cell damage either directly or through altering signaling pathways. Oxidative stress is a unifying mechanism of injury in many types of disease processes, including gastrointestinal diseases. For example, in alcoholic liver disease, reactive oxygen species have been detected through direct spin-trapping techniques and through indirect markers, such as products of lipid peroxidation. A host of antioxidants have protected against liver injury in animal models of alcoholic liver disease. Similarly, in inflammatory bowel disease, oxidative stress has been postulated to play a role in disease initiation and progression, and antioxidant therapy, such as green tea polyphenols and gene therapy with superoxide dismutase, has a markedly attenuated disease. Downregulation of specific detoxification genes may play a role in the pathogenesis of inflammatory bowel disease, especially in ulcerative colitis. Oxidative stress is postulated to play a sustaining role in acute and chronic pancreatitis. Antioxidant supplementation has been used with some success in the treatment of chronic pancreatitis. This review covers recent findings related to oxidative stress in liver disease, inflammatory bowel disease, and pancreatitis.     

Decrease in two intestinal copper/zinc containing proteins with antioxidant function in inflammatory bowel disease.

Oxygen derived radicals contribute to tissue injury in inflammatory bowel disease. We measured the content of superoxide dismutase and metallothionein (two endogenous copper and zinc containing proteins involved in radical scavenging) in intestinal resection specimens from 29 patients with Crohn's disease and 12 patients with ulcerative colitis and compared the concentrations with those obtained in the normal mucosa of a control group of 18 patients with colorectal cancer. The superoxide dismutase content was similar in control mucosa and non-inflamed mucosa from patients with inflammatory bowel disease (mean (SEM) 2.13 (0.10) and 2.24 (0.10) mg/g protein, respectively) but was decreased in inflamed mucosa (1.87 (0.08) mg/g protein, p less than 0.005 v non-inflamed mucosa). The metallothionein content was decreased in non-inflamed inflammatory bowel disease mucosa compared with control mucosa (0.23 (0.03) and 0.36 (0.04) mg/g protein, respectively, p less than 0.02) and a further decrease was found in inflamed mucosa (0.17 (0.02) mg/g protein, p less than 0.001 v control mucosa). No differences were found between Crohn's disease and ulcerative colitis and no significant effect of medication or tissue localisation was noted. These findings might indicate a decreased endogenous intestinal protection against oxygen derived radicals in inflammatory bowel disease which could contribute to the pathogenesis of the disease.     

Excessive production of reactive oxygen metabolites by inflamed colon: analysis by chemiluminescence probe.

Reactive oxygen metabolites (ROMs) are involved in inflammatory diseases and are postulated to contribute to tissue injury in colitis. To determine whether excessive ROMs are generated by inflamed colonic mucosa and to identify possible sources and type of ROMs, mucosal ROMs were estimated in rats and humans using a chemiluminescence probe. Colitis was induced in rats by intracolonic injection of acetic acid or intraperitoneal injection of mitomycin C. Intact, inflamed colon in rats produced more ultraweak chemiluminescence than normal colon. Inflamed mucosal scrapings from both rat models produced significantly more luminol-enhanced chemiluminescence. Addition of catalase, an H2O2 scavenger, or azide, a myeloperoxidase inhibitor, into the media significantly decreased chemiluminescence from inflamed mucosal scrapings. Indomethacin, an antioxidant cyclo-oxygenase inhibitor, also decreased chemiluminescence, but MK-866, a 5-lipoxygenase inhibitor, had no effect. Colonic biopsy specimens obtained during colonoscopy from patients with ulcerative colitis also produced more catalase-inhibitable chemiluminescence than normal colonic mucosa. These data indicate that excessive ROMs are produced by inflamed colonic mucosa in both humans and rats, which may contribute to tissue injury.     

Bacterial L-form isolation from inflammatory bowel disease patients

This study was designed to investigate a possible relationship between bacterial L forms and inflammatory bowel disease. Homogenates of intestinal mucosal biopsies from Crohn's disease, ulcerative colitis, and control patients underwent bacterial culture on hypertonic media designed for the recovery of L-form bacteria and parental organisms. L forms were recovered from 24 of 71 Crohn's disease, 51 of 121 ulcerative colitis, and 2 of 140 control biopsy specimens. These isolation rates are significantly different when Crohn's disease biopsy specimens (p less than 0.001) and ulcerative colitis biopsy specimens (p less than 0.001) are compared with controls. Six different L-form types were recovered, of which the most common were Escherichia coli and Streptococcus fecalis. No marked differences were observed in L-form recovery rates or L-form types recovered between Crohn's disease and ulcerative colitis patients. Drug treatment of inflammatory bowel disease patients did not affect L-form recovery rates or the type of L forms recovered. The results suggest either that L forms are involved in the causation of inflammatory bowel disease or that their presence in mucosal biopsy tissues is a result of the disease process.     

This month in the Scandinavian Journal of Gastroenterology

Background: The production of free radicals is increased in inflammatory bowel disease, and trace elements are crucial components of several antioxidants. Trace elements deficiency may therefore compromise the defense against oxidative damage. The aims of this study were to measure plasma and tissue concentration of trace elements and antioxidants and to relate this to disease activity. Methods: A 10-ml blood sample and six colonic biopsy specimens were obtained from 24 patients with either active ulcerative colitis or in remission and 10 patients with irritable bowel syndrome for measurement of trace elements and trace element-dependent enzymes. Results: Patients with moderately active disease had significantly lower plasma iron, selenium, and glutathione peroxidase levels than patients in remission and controls, whereas no significant differences were found between the zinc and copper values of patients and controls. Mucosal concentrations of zinc and metallothionein were reduced, whereas iron and glutathione peroxidase concentrations were increased in patients with endoscopically active disease as compared with controls and patients in remission. Conclusions: Patients with ulcerative colitis have altered plasma and tissue levels of trace elements and antioxidant-related enzymes. The resulting reduced protection against free radicals may contribute to the inflammatory process.     

Increased interleukin 8 expression in the colon mucosa of patients with inflammatory bowel disease.

To test whether there is a difference in the expression of interleukin 8 (IL8) between Crohn's disease and ulcerative colitis and to determine the main site of its synthesis this study analysed IL8 in mucosal biopsy specimens of patients with Crohn's disease and ulcerative colitis by enzyme linked immunosorbent assay (ELISA) and by in situ hybridisation. IL8 was measured by ELISA in 38 normal control patients, eight inflammatory control patients, 55 Crohn's disease biopsy specimens (26 patients), and 67 ulcerative colitis biopsy specimens (35 patients). IL8 mRNA was determined in samples by in situ hybridisation using a specific IL8 RNA probe. IL8 protein was significantly increased in macroscopically inflamed specimens of Crohn's disease (median 118 pg/specimen, p < 0.0001), ulcerative colitis (median 140 pg/specimen, p < 0.001), and inflammatory controls (median 30 pg/specimen, p = 0.010) compared with normal controls (median 4 pg/specimen). IL8 was also increased in uninflamed specimens of Crohn's disease (median 46 pg/specimen, p < 0.001) but not of ulcerative colitis patients (median 9 pg/specimen, p = 0.3). IL8 protein in the mucosa correlated significantly with macroscopic inflammation in Crohn's disease (r = 0.47, p < 0.001) and in ulcerative colitis (r = 0.60, p < 0.001). IL8 mRNA was detected by in situ hybridisation in 31 of 55 biopsy specimens (56%) of Crohn's disease patients, in 38 of 67 specimens of ulcerative colitis patients (57%), in five of eight inflammatory controls (63%) and in five of 38 normal controls (13%). Mucosal IL8 mRNA expression correlated with mucosal IL8 protein (r = 0.46, p < 0.001). IL8 mRNA was only detected in inflammatory cells of the interstitium but not in mucosal epithelial cells. IL8 is produced mainly in the lamina propria of the colon in inflammatory bowel disease and correlates with mucosal inflammation.     

Mucosal reactive oxygen metabolite production in duodenal ulcer disease.

To investigate the hypothesis that reactive oxygen metabolites are important in the pathophysiology of duodenal ulcer disease, their production by duodenal mucosal biopsy specimens was measured using luminol and lucigenin amplified chemiluminescence. Luminol chemiluminescence, expressed as background corrected median photon emission/mg/min x 10(3) (95% confidence intervals), was increased in duodenal inflammation as assessed macroscopically: ulcers 20.3 (4.8 to 51.3), n = 29; severe duodenitis 13.9 (6.6 to 75.3), n = 16; mild duodenitis 0.0 (-0.5 to 0.8), n = 56; controls -0.8 (-1.3 to -0.1), n = 41; p = 0.0001, Kruskal-Wallis) and microscopically: severe 17.0 (9.3 to 51.3), n = 12; moderate 0.3 (-2.8 to 5.8), n = 17; mild -0.1 (-1.8 to 1.0), n = 17; controls -0.8 (-1.6 to 0.0), n = 15; (p = 0.0001). Luminol chemiluminescence was directly related to both the macroscopic and microscopic severity of duodenal damage (Spearman's R = + 0.53, + 0.55 respectively, both p = 0.0001), to histochemical assessment (myeloperoxidase activity) of neutrophil infiltration (R = + 0.63; p = 0.04), and to lucigenin chemiluminescence (R = + 0.56, p = 0.0002). Luminol chemiluminescence was inhibited by sodium azide (-80%), catalase (-73%), and dimethyl sulphoxide (-24%). Superoxide dismutase inhibited lucigenin more than luminol dependent chemiluminescence (-61% and -7% respectively, p < 0.05). Within disease groups, Helicobacter pylori antral infection was associated with increased duodenal chemiluminescence, whereas smoking, alcohol, and use of NSAIDs or H2 blockers had no influence. Their disease related generation in duodenal mucosa supports a role for reactive oxygen metabolites in the pathogenesis of duodenitis and duodenal ulcer. These metabolites might include superoxide, hydrogen peroxide, hydroxyl, and products of myeloperoxidase activity.     

Diversion colitis: histological features in the colon and rectum after defunctioning colostomy.

Diversion of the faecal stream by ileostomy or colostomy leads to inflammation in the defunctioned segment, known as diversion colitis. The affected bowel is rapidly restored to normality by reanastomosis. Diversion colitis should not be mistaken for inflammatory bowel disease, for which reanastomosis would be inappropriate. Studies of biopsy material from patients with diversion colitis have shown a variety of histological features, but no consistent pattern. The histology in resection specimens of defunctioned large bowel from 15 patients with no pre-existing inflammatory bowel disease was studied. Nine patients had symptoms of abdominal pain or rectal discharge of blood or mucus that developed between 9 months and 17 years after diversion procedure. The histology was abnormal in all. Findings were similar in 14 patients, regardless of the duration of faecal diversion, and comprised diffuse mild chronic inflammation with or without mild crypt architectural abnormalities, crypt abscesses, or follicular lymphoid hyperplasia. One patient had more severe changes, resembling active ulcerative colitis. These features in biopsy specimens are unlikely to be diagnostic but should provide useful information in avoiding a mistaken diagnosis of inflammatory bowel disease in these patients.     

Histologic Changes in Defunctioned Rectums in Patients With Inflammatory Bowel Disease

PURPOSE: Inflammation occurs in defunctioned rectums in patients without inflammatory bowel disease. Defunctioned rectums in patients with inflammatory bowel disease have additional histopathologic changes that can cause diagnostic confusion. The aim of this study was to ascertain whether histologic changes in defunctioned rectums had any association with original pathologic diagnosis in the colectomy specimen, duration of defunctionalization, or occurrence of Crohn's disease-like complications during follow-up. METHODS: In this retrospective study, we reviewed the patient records and reexamined histologically the defunctioned rectums and original colectomy specimens of 84 consecutive patients encountered between 1983 and 1986. RESULTS: All excised rectal specimens had ulcers and erosions, usually with prominent mucosal lymphoid aggregates, often with mucosal atrophy, diffuse mucin depletion, and marked mucosal architectural distortion. Transmural lymphoid aggregates were identified in 56 patients (67 percent) and were graded as moderate or marked in 35 (42 percent). Ten rectal specimens contained nonnecrotizing granulomas. The original pathologic diagnoses from the colectomy specimens were as follows: ulcerative colitis (n = 22), Crohn's disease (n = 19), indeterminate colitis (n = 41), adenocarcinoma (n = 1), and diverticular disease (n = 1). Only mild histologic changes were observed in rectal specimens from patients with diverticular disease and adenocarcinoma, and granulomas were identified more frequently in Crohn's disease patients. Otherwise, no feature in the defunctioned rectum was associated with the original diagnosis or duration of defunctionalization. Sixteen patients (19 percent) had late surgical complications suggestive of Crohn's disease (abscess, fistula, or subsequent biopsy specimen containing nonnecrotizing granulomas) after a median follow-up of 4.8 years. Five were patients categorized as having Crohn's disease with colectomy specimen, nine had indeterminate colitis, and two had ulcerative colitis. No histologic feature in the defunctioned rectum was associated with Crohn's disease-like complications. CONCLUSIONS: Granulomas in a defunctioned rectum were associated with an original diagnosis of Crohn's disease. Transmural lymphoid aggregates were common in defunctioned rectums in patients with inflammatory bowel disease and did not indicate Crohn's disease. Other histologic changes developed independently of diagnosis and duration of defunctionalization.     

Positioning novel biologic,probiotic, and apheresis therapies for crohn’s disease and ulcerative colitis

Traditional medications for inflammatory bowel disease are small molecule drugs, most of which were developed for use in other diseases before being found to be efficacious for the treatment of ulcerative colitis or Crohn’s disease. Recently, several exciting alternative approaches to the medical treatment of inflammatory bowel disease have been developed. These include biologic, probiotic, and apheresis therapies that offer certain advantages over traditional drug therapy for inflammatory bowel disease. The purpose of this review is to assess the current state of knowledge about novel biologic, probiotic, and apheresis therapies and to analyze how best to incorporate these therapies into evolving management paradigms of inflammatory bowel disease.     

The differential diagnosis of idiopathic inflammatory disease by colorectal biopsy

Summary The differential diagnosis of idiopathic inflammatory bowel disease by colorectal biopsy poses a challenge to the endoscopist as well as the pathologist. Distinguishing non-idiopathic colitis from idiopathic colitis is the fundamental first step. No single histopathologic feature distinguishes between non-idiopathic and idiopathic inflammatory bowel disease or between the two forms of idiopathic inflammatory bowel disease (ulcerative colitis and Crohn's disease involving the colon). Interaction between the endoscopist and pathologist is essential in optimizing the contribution of colorectal biopsy to management of patients with inflammatory bowel disease.     

Tocopherols in the Prevention and Treatment of Atherosclerosis and Related Cardiovascular Disease

Oxidants/antioxidants play an important role in cellular homeostasis. The human body has endogenous molecules that work as antioxidants, such as glutathione, superoxide dismutase, peroxidases, and catalase. Exogenous substances in the diet, such as β‐carotene, ascorbate, and vitamin E, are vital antioxidants. Of these, vitamin E is likely the most important antioxidant in the human diet, and many studies have been performed to elucidate its role in health and disease. Vitamin E is a family of several compounds, of which α‐tocopherol is the most widely known analog. α‐Tocopherol exhibits antioxidative property in vitro and inhibits oxidation of low‐density lipoprotein cholesterol. In addition, α‐tocopherol shows anti‐inflammatory activity and modulates expression of proteins involved in the uptake, transport, and degradation of atherogenic lipids. Though α‐tocopherol exhibits important antioxidant, anti‐inflammatory, and antiatherogenic features in vitro, α‐tocopherol supplements have failed to consistently reduce atherosclerosis‐related events in human trials. The conflicting results have led to reconsideration of the importance previously given to α‐tocopherol and led to interest in other members of vitamin E family, especially γ‐tocopherol, which exerts a much more potent antioxidant, anti‐inflammatory, and cardioprotective effect than α‐tocopherol. This reconsideration has been backed by solid laboratory and clinical research. We suggest that the absence of γ‐tocopherol in traditional preparations may be one reason for the lack of consistent salutary effects of vitamin E preparations in clinical trials. This review summarizes our current understanding of tocopherols as antioxidant molecules and emerging evidence of an important role of γ‐tocopherol in the pathophysiology of atherosclerosis‐related cardiovascular disease.     

Mucosal antioxidant defense is not impaired in ulcerative colitis

BACKGROUND/AIMS: In this study, mucosal antioxidant defense was investigated in the biopsy samples from 12 patients with active ulcerative colitis and from 13 patients under remission. METHODOLOGY: Biopsy samples obtained from healthy colon parts of the same subjects were used as control. RESULTS: No changes were observed between superoxide dismutase, glutathione peroxidase and catalase enzyme activities of control or inflamed biopsy samples. However, antioxidant potential values were found to be higher and malondialdehyde levels lower in inflamed samples compared with controls. CONCLUSIONS: Our results show that in contrast to previous suggestions, mucosal antioxidant defense is not impaired in ulcerative colitis.     

Increased concentrations of interleukin 1 beta, interleukin-2, and soluble interleukin-2 receptors in endoscopical mucosal biopsy specimens with active inflammatory bowel disease.

Concentrations of interleukin-1 beta (IL-1 beta), interleukin-2 (IL-2), and soluble IL-2 receptors (sIL-2R) were determined by enzyme linked immunosorbent assays (ELISA) in supernatants of sonicated endoscopical mucosal biopsy specimens from 31 patients with inflammatory bowel disease and 19 controls. IL-1 beta was detected in 53% of the patient supernatants (p = 0.0001), IL-2 in 35% (p = 0.0031), compared with none of the controls. Soluble IL-2R was present in 55% and 26% of the specimens, respectively (p = 0.07). The concentrations of IL-1 beta (p = 0.00015), IL-2 (p = 0.0019), and sIL-2R (p = 0.0073) were highest in the most inflamed biopsy specimens, compared with less inflamed specimens and controls. There were no significant differences in IL-1 beta, IL-2, and sIL-2R concentrations between ulcerative colitis (16) and Crohn's disease patients (15). The results suggest that enhanced cellular immunity operates in vivo at the mucosal level in active inflammatory bowel disease.     

Advances in drug therapy for inflammatory bowel disease

PURPOSE: To identify advances in drug therapy for inflammatory bowel disease, and to evaluate the effectiveness of the new agents in treating both ulcerative colitis and Crohn disease. DATA IDENTIFICATION: Studies published from January 1980 through June 1989 were identified using MEDLINE and through extensive hand searching of bibliographies in identified articles. STUDY SELECTION: One hundred and ten articles directly related to the topic were found and analyzed. Another 42 articles were relevant to the material reviewed. DATA EXTRACTION: Articles were selected on the basis of study quality and their significance with regard to treatment of inflammatory bowel disease. RESULTS OF DATA ANALYSIS: The aminosalicylates are emerging as effective and safe therapy for inflammatory bowel disease. Corticotropin can be considered the drug of choice for certain patients with severe ulcerative colitis, and new rapidly metabolized topical steroids appear to be as effective as traditional forms and have fewer side effects. Immunosuppressive agents, including 6-mercaptopurine and azathioprine, may be useful in treating difficult-to-manage patients with either Crohn disease or ulcerative colitis, whereas cyclosporine appears promising but should be reserved for patients in whom other measures have failed. Patients with refractory perineal Crohn disease and those with Crohn colitis may benefit from metronidazole. Many other drugs including clonidine, cromoglycate, chloroquine, fish oil, methotrexate, antituberculous agents, interferon, and superoxide dismutase have shown enough promise in preliminary studies to warrant controlled clinical trials. CONCLUSIONS: Drug therapy for inflammatory bowel disease, limited for many years to sulfasalazine and some corticosteroids, has been extended to include the aminosalicylates, rapidly metabolized topical steroids, immunosuppressive agents, and metronidazole. Potentially useful newer drugs await further study.     

Prevalence of Cytomegalovirus Infection in Inflammatory Bowel Disease Patients

PURPOSE Although there has been an increasing number of case reports on inflammatory bowel disease complicated by cytomegalovirus infection, few reports have described its prevalence. The aim of this study was to investigate the prevalence of cytomegalovirus infection in inflammatory bowel disease and clarify the clinicopathologic features of the cases.METHODS We studied 55 biopsy specimens and 39 surgical specimens taken from patients clinically diagnosed as having ulcerative colitis, and 49 biopsy specimens and 30 surgical specimens from patients clinically diagnosed as having Crohns disease. In all cases cytomegalovirus infection was histopathologically examined by means of hematoxylin and eosin and immunohistochemical staining to detect inclusion bodies in specimens.RESULTS Cytomegalovirus infection was confirmed in 1 of 55 biopsy specimens and in 8 of 39 surgical specimens obtained from the cases with ulcerative colitis. No cytomegalovirus inclusion bodies were exhibited in the 49 biopsy specimens and 30 surgical specimens taken from patients with Crohns disease.CONCLUSIONS Cytomegalovirus infection was detected rather frequently (21 percent) in the surgical specimens of ulcerative colitis, and all cases were steroid resistant. The possibility of cytomegalovirus infection should always be taken into account in patients with ulcerative colitis who are resistant to steroid therapy.     

Melatonin Expresses Powerful Anti-inflammatory and Antioxidant Activities Resulting in Complete Improvement of Acetic-Acid-Induced Colitis in Rats

Introduction  

Increased free-radical production, decreased antioxidant capacity, and excessive inflammation are well-known features in the pathogenesis of inflammatory bowel disease. Melatonin is a powerful antioxidant and a scavenger of hydroxyl radicals. Melatonin has also been shown to have anti-inflammatory activities in tissues. Our study objective is to investigate the effects of melatonin on tissue inflammatory activities using an ulcerative colitis (UC) model induced by acetic acid (AA) in rats.     

The Implications of Oxidative Stress and Antioxidant Therapies in Inflammatory Bowel Disease: Clinical Aspects and Animal Models

Inflammatory bowel disease (IBD), including Crohn''s disease (CD) and ulcerative colitis (UC), is a chronic inflammatory disorder characterized by alternating phases of clinical relapse and remission. The etiology of IBD remains largely unknown, although a combination of patient''s immune response, genetics, microbiome, and environment plays an important role in disturbing intestinal homeostasis, leading to development and perpetuation of the inflammatory cascade in IBD. As chronic intestinal inflammation is associated with the formation of reactive oxygen and reactive nitrogen species (ROS and RNS), oxidative and nitrosative stress has been proposed as one of the major contributing factor in the IBD development. Substantial evidence suggests that IBD is associated with an imbalance between increased ROS and decreased antioxidant activity, which may explain, at least in part, many of the clinical pathophysiological features of both CD and UC patients. Hereby, we review the presently known oxidant and antioxidant mechanisms involved in IBD-specific events, the animal models used to determine these specific features, and also the antioxidant therapies proposed in IBD patients.Key Words: Animal models, antioxidants, Crohn''s disease, lipid peroxidation, reactive oxygen species, ulcerative colitis