Attenuated mild colonic inflammation and improved survival from severe DSS-colitis of transgenic Cu/Zn-SOD mice

Colon-targeted delivery of niclosamide from solid dispersion employing a pH-dependent polymer via hotmelt extrusion for the treatment of ulcerative colitis in mice

Niclosamide (NCL) is repurposed to treat inflammatory bowel disease due to its anti-inflammatory properties and potential to reduce oxidative stress. This therapeutic activity remains challenging if administered directly due to its low solubility and high recrystallization tendency in gastric pH. Solid dispersions using pH-dependent polymer will be a better idea to improve the solubility, dissolution and targeted delivery at the colon. Hot melt extrusion was used to formulate a solid dispersion with 30% NCL utilising hydroxypropyl methylcellulose acetate succinate as a pH-dependent polymer. In vitro drug release studies revealed formulation (F1) containing 10%w/w Tween 80 showed minimal release (2.06%) at the end of 2 h, followed by 47.87% and 82.15% drug release at 6 h and 14 h, respectively, indicating the maximum amount of drug release in the colon. The drug release from the formulations containing no plasticiser and 5%w/w plasticiser was comparable to the pure crystalline drug (approximately 25%). Solid-state analysis confirmed particle conversion of crystalline NCL to amorphous form, and the optimised formulation was stable for 6 months without significant changes in dissolution profile. In contrast to pure NCL, the F1 formulation substantially reduced the disease activity index, colonic inflammation, histological alterations and oxidative damage in colitis mice. These findings reveal that the prepared formulation can potentially deliver the drug locally at the colon, making it an effective tool in treating ulcerative colitis.

Polysaccharides from Tetrastigma Hemsleyanum Diels et Gilg ameliorated inflammatory bowel disease by rebuilding the intestinal mucosal barrier and inhibiting inflammation through the SCFA-GPR41/43 signaling pathway

In this study, the therapeutic effects of Tetrastigma hemsleyanum polysaccharide (THP) on inflammatory bowel disease (IBD) and its possible mechanisms were investigated based on the IBD mouse model induced by dextran sodium sulfate (DSS) and the lipopolysaccharide (LPS)-stimulated Caco-2 cell model. THP significantly alleviated the signs and symptoms of DSS-induced IBD mice, including the reduced weight, shortened colonic length, and increased colitis disease activity index. In vivo, THP significantly reduced inflammatory cell infiltration and oxidative damage, promoted intestinal mucus secretion, and restored the integrity of the intestinal epithelial barrier and mucus barrier. Furthermore, THP reversed the changes in the intestinal flora of colonized mice and restored the levels of short-chain fatty acids (SCFAs) by increasing the abundance of potentially beneficial bacteria and increasing the abundance of butyrate-producing bacteria. In addition, THP upregulated the expression of G-protein-coupled receptors (GPR41 and GPR43) both in vivo and in vitro. In summary, the current investigation showed that THP effectively protected against intestinal inflammation and impairment in the intestinal barrier in the setting of DSS-induced IBD, possibly by regulating gut microbiota structure and corresponding SCFA metabolites, and the pathway of SCFAs action may be related to SCFA-GPR41/43 signaling pathway.

Neuropeptide W Exhibits Preventive and Therapeutic Effects on Acetic Acid-Induced Colitis via Modulation of the Cyclooxygenase Enzyme System

BACKGROUND

The novel peptide neuropeptide W (NPW) was originally shown to function in the control of feeding behavior and energy homeostasis. The aim of this study was to elucidate the putative preventive and therapeutic effects of NPW on colitis-associated oxidative injury and the underlying mechanisms for its action.

METHODS

Sprague-Dawley rats in the acute colitis groups received NPW (0.5, 1 or 5 µg/kg/day) injections prior to induction of colitis with acetic acid, while the chronic colitis groups were treated after the induction of colitis. In both acute and chronic colitis (CC) groups, treatments were continued for 5 days and the rats were decapitated at the 24th hour of the last injections and colon tissues were collected for assessments.

RESULTS

NPW pretreatment given for 5 days before colitis induction, as well as treating rats with NPW during the 5-day course of CC, abolished colonic lipid peroxidation. NPW treatment prevented colitis-induced reduction in blood flow, diminished neutrophil infiltration, and pro-inflammatory cytokine responses. NPW pretreatment only at the higher dose reduced colonic edema and microscopic score and preserved colonic glutathione stores. Elevations in cyclooxygenase (COX) enzyme activity and COX-1 protein level during the acute phase of colitis as well as reduction in COX-2 were all reversed with NPW pretreatment. In contrast, NPW treatment was effective in reducing the elevated COX-2 concentration during the chronic phase.

CONCLUSIONS

NPW alleviates acetic acid-induced oxidative colonic injury in rats through the upregulation of colonic blood flow as well as the inhibition of COX-2 protein expression and pro-inflammatory cytokine production.

A new therapy against ulcerative colitis via the intestine and brain using the Si-based agent

Ulcerative colitis (UC) is a non-specific inflammatory bowel disease that causes ulcers and erosions in the colonic mucosa and becomes chronic with cycles of amelioration and exacerbation. Because its exact etiology remains largely unclear, and the primary therapy is limited to symptomatic treatment, the development of new therapeutic agent for UC is highly desired. Because one of the disease pathogenesis is involvement of oxidative stress, it is likely that an appropriate antioxidant will be an effective therapeutic agent for UC. Our silicon (Si)-based agent, when ingested, allowed for stable and persistent generation of massive amounts of hydrogen in the gastrointestinal tract. We demonstrated the Si-based agent alleviated the mental symptom as well as the gastrointestinal symptoms, inflammation, and oxidation associated with dextran sodium sulfate-induced UC model through Hydrogen and antioxidant sulfur compounds. As the Si-based agent was effective in treating UC in the brain and large intestine of mice, it was considered to be capable of suppressing exacerbations and sustaining remission of UC.

A recombinant Bifidobacterium bifidum BGN4 strain expressing the streptococcal superoxide dismutase gene ameliorates inflammatory bowel disease

Background

Inflammatory bowel disease (IBD) is a gastrointestinal disease characterized by diarrhea, rectal bleeding, abdominal pain, and weight loss. Recombinant probiotics producing specific proteins with IBD therapeutic potential are currently considered novel drug substitutes. In this study, a Bifidobacterium bifidum BGN4-SK strain was designed to produce the antioxidant enzymes streptococcal superoxide dismutase (SOD) and lactobacillus catalase (CAT), and a B. bifidum BGN4-pBESIL10 strain was proposed to generate an anti-inflammatory cytokine, human interleukin (IL)-10. In vitro and in vivo efficacy of these genetically modified Bifidobacterium strains were evaluated for colitis amelioration.

Results

In a lipopolysaccharide (LPS)-stimulated HT-29 cell model, tumor necrosis factor (TNF)-α and IL-8 production was significantly suppressed in the B. bifidum BGN4-SK treatment, followed by B. bifidum BGN4-pBESIL10 treatment, when compared to the LPS-treated control. Synergistic effects on TNF-α suppression were also observed. In a dextran sodium sulphate (DSS)-induced colitis mouse model, B. bifidum BGN4-SK treatment significantly enhanced levels of antioxidant enzymes SOD, glutathione peroxidase (GSH-Px) and CAT, compared to the DSS-only group. B. bifidum BGN4-SK significantly ameliorated the symptoms of DSS-induced colitis, increased the expression of tight junction genes (claudin and ZO-1), and decreased pro-inflammatory cytokines IL-6, IL-1β and TNF-α.

Conclusions

These findings suggest that B. bifidum BGN4-SK ameliorated DSS-induced colitis by generating antioxidant enzymes, maintaining the epithelial barrier, and decreasing the production of pro-inflammatory cytokines. Although B. bifidum BGN4-pBESIL10 exerted anti-inflammatory effects in vitro, the enhancement of IL-10 production and alleviation of colitis were very limited.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-022-01840-2.

Oxidative Stress and Antioxidant Nanotherapeutic Approaches for Inflammatory Bowel Disease

Oxidative stress, caused by the accumulation of reactive species, is associated with the initiation and progress of inflammatory bowel disease (IBD). The investigation of antioxidants to target overexpressed reactive species and modulate oxidant stress pathways becomes an important therapeutic option. Nowadays, antioxidative nanotechnology has emerged as a novel strategy. The nanocarriers have shown many advantages in comparison with conventional antioxidants, owing to their on-site accumulation, stability of antioxidants, and most importantly, intrinsic multiple reactive species scavenging or catalyzing properties. This review concludes an up-to-date summary of IBD nanomedicines according to the classification of the delivered antioxidants. Moreover, the concerns and future perspectives in this study field are also discussed.

Induction of colitis-associated neoplasia in mice using azoxymethane and dextran sodium sulfate

Long-standing inflammatory bowel diseases (IBD) increase the risk for the development of colorectal cancer (CRC). This increase is due in large part to chronic intestinal inflammation which exposes the epithelium to pro-carcinogenic factors. Moreover, enhanced mucosal proliferation associated with repetitive wound healing events following an inflammatory episode, further enhance this pro-tumorigenic environment. Although multiple factors involved in IBD pathogenesis and its associated neoplasia have been identified, more work is needed to develop and improve therapies to ameliorate disease and thus reduce CRC risk. Murine models have served as useful tools to identify factors involved in the pathogenesis of colitis-associated neoplasia and test therapies. These include both chemically-induced and genetic engineering approaches, resulting in chronic inflammation and tumor development. Here, we present a step-by-step method of inducing inflammation-associated colon neoplasia by combining administration of azoxymethane and dextran sodium sulfate in mice. A detailed description of this methodology will facilitate its use in the scientific community with the goals of further elucidating the mechanisms underlying colitis-associated tumorigenesis and developing risk reducing interventions.

Dietary Fructose Alters the Composition, Localization, and Metabolism of Gut Microbiota in Association With Worsening Colitis

BACKGROUND & AIMS

The incidence of inflammatory bowel diseases has increased over the last half century, suggesting a role for dietary factors. Fructose consumption has increased in recent years. Recently, a high fructose diet (HFrD) was shown to enhance dextran sodium sulfate (DSS)-induced colitis in mice. The primary objectives of the current study were to elucidate the mechanism(s) underlying the pro-colitic effects of dietary fructose and to determine whether this effect occurs in both microbially driven and genetic models of colitis.

METHODS

Antibiotics and germ-free mice were used to determine the relevance of microbes for HFrD-induced worsening of colitis. Mucus thickness and quality were determined by histologic analyses. 16S rRNA profiling, in situ hybridization, metatranscriptomic analyses, and fecal metabolomics were used to determine microbial composition, spatial distribution, and metabolism. The significance of HFrD on pathogen and genetic-driven models of colitis was determined by using Citrobacter rodentium infection and Il10^-/- mice, respectively.

RESULTS

Reducing or eliminating bacteria attenuated HFrD-mediated worsening of DSS-induced colitis. HFrD feeding enhanced access of gut luminal microbes to the colonic mucosa by reducing thickness and altering the quality of colonic mucus. Feeding a HFrD also altered gut microbial populations and metabolism including reduced protective commensal and bile salt hydrolase-expressing microbes and increased luminal conjugated bile acids. Administration of conjugated bile acids to mice worsened DSS-induced colitis. The HFrD also worsened colitis in Il10^-/- mice and mice infected with C rodentium.

CONCLUSIONS

Excess dietary fructose consumption has a pro-colitic effect that can be explained by changes in the composition, distribution, and metabolic function of resident enteric microbiota.

Molecules from American Ginseng Suppress Colitis through Nuclear Factor Erythroid-2-Related Factor 2

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that affects millions of people worldwide and increases the risk of colorectal cancer (CRC) development. We have previously shown that American ginseng (AG) can treat colitis and prevent colon cancer in mice. We further fractionated AG and identified the most potent fraction, hexane fraction (HAG), and the most potent compound in this fraction, panaxynol (PA). Because (1) oxidative stress plays a significant role in the pathogenesis of colitis and associated CRC and (2) nuclear factor erythroid-2-related factor 2 (Nrf2) is the master regulator of antioxidant responses, we examined the role of Nrf2 as a mechanism by which AG suppresses colitis. Through a series of in vitro and in vivo Nrf2 knockout mouse experiments, we found that AG and its components activate the Nrf2 pathway and decrease the oxidative stress in macrophages (mΦ) and colon epithelial cells in vitro. Consistent with these in vitro results, the Nrf2 pathway is activated by AG and its components in vivo, and Nrf2^-/- mice are resistant to the suppressive effects of AG, HAG and PA on colitis. Results from this study establish Nrf2 as a mediator of AG and its components in the treatment of colitis.

The Exacerbation of Aging and Oxidative Stress in the Epididymis of Sod1 Null Mice

There is growing evidence that the quality of spermatozoa decreases with age and that children of older fathers have a higher incidence of birth defects and genetic mutations. The free radical theory of aging proposes that changes with aging are due to the accumulation of damage induced by exposure to excess reactive oxygen species. We showed previously that absence of the superoxide dismutase 1 (Sod1) antioxidant gene results in impaired mechanisms of repairing DNA damage in the testis in young Sod1^−/− mice. In this study, we examined the effects of aging and the Sod^−/− mutation on mice epididymal histology and the expression of markers of oxidative damage. We found that both oxidative nucleic acid damage (via 8-hydroxyguanosine) and lipid peroxidation (via 4-hydroxynonenal) increased with age and in Sod1^−/− mice. These findings indicate that lack of SOD1 results in an exacerbation of the oxidative damage accumulation-related aging phenotype.

Preventive Effect of Lactobacillus Plantarum CQPC10 on Activated Carbon Induced Constipation in Institute of Cancer Research (ICR) Mice

Chinese Paocai is a traditional fermented food containing an abundance of beneficial microorganisms. In this study, the microorganisms in Szechwan Paocai were isolated and identified, and a strain of lactic acid bacteria (Lactobacillus plantarum CQPC10, LP-CQPC10) was found to exert an inhibitory effect on constipation. Microorganisms were isolated and identified via 16S rDNA. Activated carbon was used to induce constipation in a mouse model and the inhibitory effect of LP-CQPC10 on this induced constipation was investigated via both pathological sections and qPCR (quantitative polymerase chain reaction). A strain of Lactobacillus plantarum was identified and named LP-CQPC10. The obtained results showed that, as compared to the control group, LP-CQPC10 significantly inhibited the amount, weight, and water content of faeces. The defecation time of the first tarry stool was significantly shorter in LP-CQPC10 groups than in the control group. The activated carbon progradation rate was significantly higher when compared to the control group and the effectiveness was improved. LP-CQPC10 increased the serum levels of MTL (motilin), Gas (gastrin), ET (endothelin), AchE (acetylcholinesterase), SP (substance P), and VIP (vasoactive intestinal peptide), while decreasing the SS (somatostatin) level. Furthermore, it improved the GSH (glutathione) level and decreased the MPO (myeloperoxidase), MDA (malondialdehyde), and NO (nitric oxide) levels. The results of qPCR indicated that LP-CQPC10 significantly up-regulated the mRNA expression levels of c-Kit, SCF (stem cell factor), GDNF (glial cell-derived neurotrophic factor), eNOS (endothelial nitric oxide synthase), nNOS (neuronal nitric oxide synthase), and AQP3 (aquaporin-3), while down-regulating the expression levels of TRPV1 (transient receptor potential cation channel subfamily V member 1), iNOS (inducible nitric oxide synthase), and AQP9 (aquaporin-9). LP-CQPC10 showed a good inhibitory effect on experimentally induced constipation, and the obtained effectiveness is superior to that of Lactobacillus bulgaricus, indicating the better probiotic potential of this strain.

Prdx6 Deficiency Ameliorates DSS Colitis: Relevance of Compensatory Antioxidant Mechanisms

BACKGROUND AND AIMS

An imbalance between cellular antioxidant defence system[s] and reactive oxygen species [ROS]-driven oxidative stress has been implicated in the pathogenesis of inflammatory bowel disease. Peroxiredoxin [PRDX] 6 contributes to an appropriate redox balance by clearing ROS and reducing peroxidized membrane phospholipids. We here studied the role of PRDX6 in acute and chronic dextran sodium sulphate [DSS]-induced colitis.

METHODS

To investigate the impact of PRDX6 on intestinal inflammation, we used wild type [WT], Prdx6 knock-out mice [Prdx6-/-] and transgenic mice [Prdx6tg/tg], overexpressing Prdx6. Acute and chronic colitis was induced by DSS in WT, Prdx6-/- and Prdx6tg/tg mice. Colitis was evaluated by endoscopy, colon length, histopathological assessment and myeloperoxidase [MPO] activity. Changes in mRNA and protein expression of pro-inflammatory cytokines and antioxidant enzymes were evaluated by real-time quantitative polymerase chain reaction [RT-qPCR] and western blot. Total glutathione [GSH] levels in colon samples were determined.

RESULTS

Prdx6-/- mice exposed to acute and chronic DSS showed a significant decrease in the clinical parameters and in colonic expression of pro-inflammatory cytokines compared with WT mice. mRNA expression of antioxidant enzymes in colon samples was significantly increased in Prdx6-/- compared with WT mice exposed to acute and chronic DSS. In addition, total GSH levels were increased in Prdx6-/- mice treated with DSS in comparison with WT. Overexpression of Prdx6 did not significantly influence acute and chronic colitis.

CONCLUSIONS

Our data indicate that a lack of the antioxidant enzyme PRDX6 protects against the development of acute and chronic experimental colitis and is associated with increased expression and function of other antioxidant enzymes, suggesting effective compensatory mechanisms.

Pathomechanisms of Oxidative Stress in Inflammatory Bowel Disease and Potential Antioxidant Therapies

Inflammatory bowel disease (IBD) is a chronic gastrointestinal disease whose incidence has risen worldwide in recent years. Accumulating evidence shows that oxidative stress plays an essential role in the pathogenesis and progression of IBD. This review highlights the generation of reactive oxygen species (ROS) and antioxidant defense mechanisms in the gastrointestinal (GI) tract, the involvement of oxidative stress signaling in the initiation and progression of IBD and its relationships with genetic susceptibility and the mucosal immune response. In addition, potential therapeutic strategies for IBD that target oxidative stress signaling are reviewed and discussed. Though substantial progress has been made in understanding the role of oxidative stress in IBD in humans and experimental animals, the underlying mechanisms are still not well defined. Thus, further studies are needed to validate how oxidative stress signaling is involved in and contributes to the development of IBD.

Altered gut microbiome in a mouse model of Gulf War Illness causes neuroinflammation and intestinal injury via leaky gut and TLR4 activation

Many of the symptoms of Gulf War Illness (GWI) that include neurological abnormalities, neuroinflammation, chronic fatigue and gastrointestinal disturbances have been traced to Gulf War chemical exposure. Though the association and subsequent evidences are strong, the mechanisms that connect exposure to intestinal and neurological abnormalities remain unclear. Using an established rodent model of Gulf War Illness, we show that chemical exposure caused significant dysbiosis in the gut that included increased abundance of phylum Firmicutes and Tenericutes, and decreased abundance of Bacteroidetes. Several gram negative bacterial genera were enriched in the GWI-model that included Allobaculum sp. Altered microbiome caused significant decrease in tight junction protein Occludin with a concomitant increase in Claudin-2, a signature of a leaky gut. Resultant leaching of gut caused portal endotoxemia that led to upregulation of toll like receptor 4 (TLR4) activation in the small intestine and the brain. TLR4 knock out mice and mice that had gut decontamination showed significant decrease in tyrosine nitration and inflammatory mediators IL1β and MCP-1 in both the small intestine and frontal cortex. These events signified that gut dysbiosis with simultaneous leaky gut and systemic endotoxemia-induced TLR4 activation contributes to GW chemical-induced neuroinflammation and gastrointestinal disturbances.

Redox signaling in the gastrointestinal tract

Redox signaling regulates physiological self-renewal, proliferation, migration and differentiation in gastrointestinal epithelium by modulating Wnt/β-catenin and Notch signaling pathways mainly through NADPH oxidases (NOXs). In the intestine, intracellular and extracellular thiol redox status modulates the proliferative potential of epithelial cells. Furthermore, commensal bacteria contribute to intestine epithelial homeostasis through NOX1- and dual oxidase 2-derived reactive oxygen species (ROS). The loss of redox homeostasis is involved in the pathogenesis and development of a wide diversity of gastrointestinal disorders, such as Barrett's esophagus, esophageal adenocarcinoma, peptic ulcer, gastric cancer, ischemic intestinal injury, celiac disease, inflammatory bowel disease and colorectal cancer. The overproduction of superoxide anion together with inactivation of superoxide dismutase are involved in the pathogenesis of Barrett's esophagus and its transformation to adenocarcinoma. In Helicobacter pylori-induced peptic ulcer, oxidative stress derived from the leukocyte infiltrate and NOX1 aggravates mucosal damage, especially in HspB+ strains that downregulate Nrf2. In celiac disease, oxidative stress mediates most of the cytotoxic effects induced by gluten peptides and increases transglutaminase levels, whereas nitrosative stress contributes to the impairment of tight junctions. Progression of inflammatory bowel disease relies on the balance between pro-inflammatory redox-sensitive pathways, such as NLRP3 inflammasome and NF-κB, and the adaptive up-regulation of Mn superoxide dismutase and glutathione peroxidase 2. In colorectal cancer, redox signaling exhibits two Janus faces: On the one hand, NOX1 up-regulation and derived hydrogen peroxide enhance Wnt/β-catenin and Notch proliferating pathways; on the other hand, ROS may disrupt tumor progression through different pro-apoptotic mechanisms. In conclusion, redox signaling plays a critical role in the physiology and pathophysiology of gastrointestinal tract.

Effects of Prunus mume Sieb. et Zucc. extract and its biopolymer encapsulation on a mouse model of colitis

BACKGROUND

Prunus mume suppresses various diseases caused by inflammation response and exhibits antioxidant and free radical-scavenging activities. Therefore this study determined the effect of an aqueous P. mume (PM) extract in a mouse colitis model and investigated the value of biopolymer encapsulation, facilitating targeted delivery to the colon. Colitis was induced by administration of 30 g kg^-1 dextran sulfate sodium to male BALB/c mice for 7 days prior to treatment with vehicle, 50 mg kg^-1 PM extract or biopolymer-encapsulated PM extract, or 50 mg kg^-1 sulfasalazine.

RESULTS

Histological examination of the colon in BALB/c mice showed epithelial destruction and mucosal infiltration of inflammatory cells. These changes were attenuated in PM-treated mice, which had lower levels of inflammatory cytokines, cyclooxygenase 2 and immunoglobulins (IgA, IgM and IgE) compared with the vehicle-treated colitis group. The PM extract showed concentration-dependent radical scavenging and superoxide dismutase-like antioxidant activities.

CONCLUSION

These results indicated that the effects of the PM extract on colitis were not influenced by biopolymer encapsulation and that this PM extract could be a potential therapeutic agent for inflammatory bowel disease. © 2016 Society of Chemical Industry.

Hepato- and gastro- protective activity of purified oat 1-3, 1-4-β-d-glucans of different molecular weight

Protective and antioxidant properties of highly purified oat β-glucans of high and low molecular weight in liver and stomach were evaluated. The novelty in approach was to determine whether dietary β-glucans affect the parameters of oxidative stress directly in the stomach and indirectly in the liver, especially in inflammation states. Physicochemical properties e.g. viscoelastic was found as strictly dependent from molecular weight of oat β-glucans hence its metabolic activity could also show dependence. Three groups of rats were fed control diet and diet supplemented with low and high molecular weights oat β-glucans. Animals were divided into controls and individuals with experimentally induced intestinal inflammation. Most active in increasing of total antioxidant status was low molecular weight β-glucan. High molecular weight β-glucan supplementation inhibits lipid oxidation the most in LPS treated animals. The results obtained from experiment encourage for dietary intervention with oat β-glucans for stomach and liver protection during existing enteritis.

Impact of basal diet on dextran sodium sulphate (DSS)-induced colitis in rats

PURPOSE

Dextran sodium sulphate (DSS)-induced colitis is a widely used model for inflammatory bowel disease. However, various factors including nutrition may affect the development of this colitis. This study aimed to compare and characterize the impact of purified and non-purified basal diets on the development of DSS-induced colitis in the rat.

METHODS

Wistar rats were fed a non-purified or a semi-synthetic purified diet for 21 days. Colitis was then induced in half of the rats by administration of DSS in drinking water (4% w/v) during the last 7 days of experimentation. At the end of the experimental period, colon sections were taken for histopathological examination, determination of various markers of inflammation (myeloperoxidase: MPO, cytokines) and oxidative stress (superoxide dismutase: SOD, catalase: CAT, glutathione peroxidase: GPx and glutathione reductase: GRed activities), and evaluation of the expression of various genes implicated in this disorder.

RESULTS

DSS ingestion induced a more marked colitis in animals receiving the purified diet, as reflected by higher histological score and increased MPO activity. A significant decrease in SOD and CAT activities was also observed in rats fed the purified diet. Also, in these animals, administration of DSS induced a significant increase in interleukin (IL)-1α, IL-1β and IL-6. In addition, various genes implicated in inflammation were over-expressed after ingestion of DSS by rats fed the purified diet.

CONCLUSIONS

These results show that a purified diet promotes the onset of a more severe induced colitis than a non-purified one, highlighting the influence of basal diet in colitis development.

Zinc and gastrointestinal disease

This review is a current summary of the role that both zinc deficiency and zinc supplementation can play in the etiology and therapy of a wide range of gastrointestinal diseases. The recent literature describing zinc action on gastrointestinal epithelial tight junctions and epithelial barrier function is described. Zinc enhancement of gastrointestinal epithelial barrier function may figure prominently in its potential therapeutic action in several gastrointestinal diseases.

Gender differences, aging and hormonal status in mucosal injury and repair

As the "baby boomers" age, the percentage of the population over sixty-five years of age is increasing rapidly. Chronic disease management is an important component in the care of the elderly. The effects of aging on different organ systems are also pertinent; such as the weakening homeostatic response to injury in the older individuals. Mucosal surfaces have the largest combined surface area in the body and are the site of important host microbe interactions, especially in the gut which is prone to injury, both from local and systemic insult. This susceptibility has been known to increase with age. Therefore it is important to understand the interplay between aging, injury and recovery at the mucosal surface. Sex hormones play an important role in the maintenance of the mucosal barrier function as well as the mucosa associated immune function in both genders. Menopause in women is a defined time period in which major hormonal changes occur such as a decline in systemic estradiol levels. The differential levels of sex hormones contribute to the sexual dimorphism seen in response to injury at the mucosal surface, prior to and following menopause. Thus the effect of sex hormone and aging on mucosal mechanisms in response to injury is an important area of investigation.

Genetically engineered immunomodulatory Streptococcus thermophilus strains producing antioxidant enzymes exhibit enhanced anti-inflammatory activities

The aims of this study were to develop strains of lactic acid bacteria (LAB) having both immunomodulatory and antioxidant properties and to evaluate their anti-inflammatory effects both in vitro, in different cellular models, and in vivo, in a mouse model of colitis. Different Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains were cocultured with primary cultures of mononuclear cells. Analysis of the pro- and anti-inflammatory cytokines secreted by these cells after coincubation with candidate bacteria revealed that L. delbrueckii subsp. bulgaricus CRL 864 and S. thermophilus CRL 807 display the highest anti-inflammatory profiles in vitro. Moreover, these results were confirmed in vivo by the determination of the cytokine profiles in large intestine samples of mice fed with these strains. S. thermophilus CRL 807 was then transformed with two different plasmids harboring the genes encoding catalase (CAT) or superoxide dismutase (SOD) antioxidant enzymes, and the anti-inflammatory effects of recombinant streptococci were evaluated in a mouse model of colitis induced by trinitrobenzenesulfonic acid (TNBS). Our results showed a decrease in weight loss, lower liver microbial translocation, lower macroscopic and microscopic damage scores, and modulation of the cytokine production in the large intestines of mice treated with either CAT- or SOD-producing streptococci compared to those in mice treated with the wild-type strain or control mice without any treatment. Furthermore, the greatest anti-inflammatory activity was observed in mice receiving a mixture of both CAT- and SOD-producing streptococci. The addition of L. delbrueckii subsp. bulgaricus CRL 864 to this mixture did not improve their beneficial effects. These findings show that genetically engineering a candidate bacterium (e.g., S. thermophilus CRL 807) with intrinsic immunomodulatory properties by introducing a gene expressing an antioxidant enzyme enhances its anti-inflammatory activities.

Chemistry meets biology in colitis-associated carcinogenesis

The intestine comprises an exceptional venue for a dynamic and complex interplay of numerous chemical and biological processes. Here, multiple chemical and biological systems, including the intestinal tissue itself, its associated immune system, the gut microbiota, xenobiotics, and metabolites meet and interact to form a sophisticated and tightly regulated state of tissue homoeostasis. Disturbance of this homeostasis can cause inflammatory bowel disease (IBD)-a chronic disease of multifactorial etiology that is strongly associated with increased risk for cancer development. This review addresses recent developments in research into chemical and biological mechanisms underlying the etiology of inflammation-induced colon cancer. Beginning with a general overview of reactive chemical species generated during colonic inflammation, the mechanistic interplay between chemical and biological mediators of inflammation, the role of genetic toxicology, and microbial pathogenesis in disease development are discussed. When possible, we systematically compare evidence from studies utilizing human IBD patients with experimental investigations in mice. The comparison reveals that many strong pathological and mechanistic correlates exist between mouse models of colitis-associated cancer, and the clinically relevant situation in humans. We also summarize several emerging issues in the field, such as the carcinogenic potential of novel inflammation-related DNA adducts and genotoxic microbial factors, the systemic dimension of inflammation-induced genotoxicity, and the complex role of genome maintenance mechanisms during these processes. Taken together, current evidence points to the induction of genetic and epigenetic alterations by chemical and biological inflammatory stimuli ultimately leading to cancer formation.

Detection of DSS-induced gastrointestinal mucositis in mice by non-invasive optical near-infrared (NIR) imaging of cathepsin activity

Approximately 1.4 million people of the US population suffer from Inflammatory Bowel Disease (IBD) of which the most common conditions are ulcerative colitis (UC) and Crohn disease (CD). Colonoscopy and small bowel follow through are considered the current gold standard in diagnosing IBD. However, improved imaging and increased diagnostic sensitivity could be beneficial. Optical molecular imaging has the potential to become a powerful and practical tool for early detection, image-guided biopsy, and surgery in diagnosing and treating patients with IBD. Here we used a well characterized chemical model to initiate experimental IBD in mice by feeding with dextran sulfate sodium (DSS) containing drinking water in an attempt to investigate the utility of non-invasive infrared (NIR) optical imaging in the detection gastrointestinal (GI) injury. We employed a "smart probe" (ProSense680) cleaved and fluorescently activated in the NIR-spectrum by various forms of secreted cathepsins. This probe has previously been shown to serve as a biomarker for the homing of inflammatory cells to injury. Our investigation suggests that NIR optical imaging can detect cathepsin-dependent probe cleavage non-invasively in animals with DSS-induced IBD. Increased tissue probe-retention and fluorescence was associated with increased infiltration of inflammatory cells, epithelial atrophy and sterilization of the mucosa. Furthermore, using NIR-imaging ex vivo we were able to document regional "hot spots" of inflammatory damage to the large intestine suggesting this method potentially could be coupled with colonoscopy investigation to aid in the sampling and the diagnostics of IBD.

The role of polymorphonuclear leukocyte trafficking in the perpetuation of inflammation during inflammatory bowel disease

The inflammatory bowel diseases (IBDs; Crohn's disease, and ulcerative colitis) are chronically relapsing inflammatory disorders of the intestine and/or colon. The precise etiology of IBD remains unclear, but it is thought that a complex interplay between various factors including genetic predisposition, the host immune system, and the host response to luminal microbes play a role in disease pathogenesis. Furthermore, numerous lines of evidence have implicated the accumulation of large numbers of polymorphonuclear leukocyte (PMN) in the mucosa and epithelial crypts of the intestine as a hallmark of the active disease phase of IBD. Massive infiltration of PMNs is thought to be instrumental in the pathophysiology of IBD with the degree of PMN migration into intestinal crypts correlating with patient symptoms and mucosal injury. Specifically, migrated PMN have been implicated in the impairment of epithelial barrier function, tissue destruction through oxidative and proteolytic damage, and the perpetuation of inflammation through the release of inflammatory mediators. This review highlights the multifactorial role of PMN egress into the intestinal mucosa in the pathogenesis of IBD because it represents an important area of research with therapeutic implications for the amelioration of the symptoms associated with IBD.

Amelioration of dextran sulphate sodium-induced colitis in mice by echinacoside-enriched extract of Cistanche tubulosa

Echinacoside (ECH) is a major bioactive phenyethanoids in medicinal herba Cistanche and has been reported to have antiinflammatory activity and beneficial effect on wound healing in many experimental studies. This study was to test the efficacy of ECH-enriched extract of Cistanche tubulosa in the treatment of dextran sulphate sodium (DSS)-induced colitis, a preclinical model of ulcerative colitis. Oral administration of ECH extract significantly suppresses the development of acute colitis, indicated by lowering disease activity index (p < 0.0001, n = 8) and preventing colonic damage (p = 0.0336). Histological examinations showed that ECH extract treatment protected intestinal epithelium from inflammatory injury (p = 0.0249) but had less effect on inflammatory cellular infiltration (p = 0.1753). The beneficial effect of ECH extract treatment was associated with upregulation of transforming growth factor (TGF)-β1 as well as with an increase in the number of Ki67(+) proliferating cells in diseased colons (p < 0.0001). In cultured MODE-K cells, the addition of ECH extract enhanced in vitro wound healing that depended on TGF-β1 expression. These data suggest that ECH extract possesses a greater efficacy in preventing DSS-induced colitis in mice, implying the potential of ECH or its derivatives for clinically treating inflammatory bowel disease.

A low dose of fermented soy germ alleviates gut barrier injury, hyperalgesia and faecal protease activity in a rat model of inflammatory bowel disease

Pro-inflammatory cytokines like macrophage migration inhibitory factor (MIF), IL-1β and TNF-α predominate in inflammatory bowel diseases (IBD) and TNBS colitis. Increased levels of serine proteases activating protease-activated receptor 2 (PAR-2) are found in the lumen and colonic tissue of IBD patients. PAR-2 activity and pro-inflammatory cytokines impair epithelial barrier, facilitating the uptake of luminal aggressors that perpetuate inflammation and visceral pain. Soy extracts contain phytoestrogens (isoflavones) and serine protease inhibitors namely Bowman-Birk Inhibitors (BBI). Since estrogens exhibit anti-inflammatory and epithelial barrier enhancing properties, and that a BBI concentrate improves ulcerative colitis, we aimed to evaluate if a fermented soy germ extract (FSG) with standardized isoflavone profile and stable BBI content exert cumulative or synergistic protection based on protease inhibition and estrogen receptor (ER)-ligand activity in colitic rats. Female rats received orally for 15 d either vehicle or FSG with or without an ER antagonist ICI 182.780 before TNBS intracolonic instillation. Macroscopic and microscopic damages, myeloperoxidase activity, cytokine levels, intestinal paracellular permeability, visceral sensitivity, faecal proteolytic activity and PAR-2 expression were assessed 24 h, 3 d and 5 d post-TNBS. FSG treatment improved the severity of colitis, by decreasing the TNBS-induced rise in gut permeability, visceral sensitivity, faecal proteolytic activity and PAR-2 expression at all post-TNBS points. All FSG effects were reversed by the ICI 182.780 except the decrease in faecal proteolytic activity and PAR-2 expression. In conclusion, the anti-inflammatory properties of FSG treatment result from two distinct but synergic pathways i.e an ER-ligand and a PAR-2 mediated pathway, providing rationale for potential use as adjuvant therapy in IBD.

Oxidative stress and redox signaling mechanisms of inflammatory bowel disease: updated experimental and clinical evidence

Inflammatory bowel disease (IBD) comprises primarily the chronic relapsing inflammatory disorders, Crohn's disease and ulcerative colitis, with the former affecting any part of the gastrointestinal tract and the latter mainly afflicting the colon. The precise etiology of IBD remains unclear, and it is thought that interactions among various factors, including genetic factors, the host immune system and environmental factors, cause disruption of intestinal homeostasis, leading to dysregulated inflammatory responses of the gut. As inflammation is intimately related to formation of reactive intermediates, including reactive oxygen and nitrogen species (ROS/RNS), oxidative stress has been proposed as a mechanism underlying the pathophysiology of IBD. This review is intended to summarize succinctly recent new experimental and clinical evidence supporting oxidative stress as a pathophysiological component of IBD and point to the potential of using antioxidant compounds as promising therapeutic modalities of human IBD. The sources of ROS/RNS and the redox signaling mechanism underlying oxidative stress and inflammation in IBD are discussed to provide insight into the molecular basis of oxidative stress as a pathophysiological factor in IBD.

Potential Application of Probiotics in the Prevention and Treatment of Inflammatory Bowel Diseases

Lactic acid bacteria (LAB) represent a heterogeneous group of microorganisms that are naturally present in many foods and possess a wide range of therapeutic properties. The aim of this paper is to present an overview of the current expanding knowledge of the mechanisms by which LAB and other probiotic microorganisms participate in the prevention and treatment of inflammatory bowel diseases. These include changes in the gut microbiota, stimulation of the host immune responses, and reduction of the oxidative stress due to their antioxidant properties. A brief overview of the uses of genetically engineered LAB that produce either antioxidant enzymes (such as catalase and superoxide dismutase) or anti-inflammatory cytokines (such as IL-10) will also be discussed. This paper will show that probiotics should be considered in treatment protocols of IBD since they provide many beneficial effects and can enhance the effectiveness of traditional used medicines.

The role and therapeutic potential of prohibitin in disease

Prohibitin 1 (PHB1), a pleiotropic protein in the cell, has been implicated in the regulation of proliferation, apoptosis, transcription, mitochondrial protein folding, and as a cell-surface receptor. This diverse array of functions of PHB1 is attributed to the cell type studied and its subcellular localization. This review discusses recent data that indicate a diverse role of PHB1 in disease pathogenesis and suggest that targeting PHB1 may be a potential therapeutic option for treatment of diseases including cancer, inflammatory bowel disease, insulin resistance/type 2 diabetes, and obesity. These diseases are associated with increased oxidative stress and mitochondrial dysfunction and therefore, the role of PHB1 in both responses will also be discussed.

Soyasaponin I attenuates TNBS-Induced colitis in mice by inhibiting NF-κB pathway

Soybean, which contains soyasaponins and isoflavones as representative constituents, exhibits anti-inflammatory and antioxidant effects. To understand the anti-inflammatory effects of soyasaponins, we isolated soyasaponin I, a major constituent of soybean, and investigated the inhibitory effects on inflammatory markers in LPS-stimulated mouse peritoneal macrophages and 3,4,5-trinitrobenzenosulfonic acid (TNBS)-induced colitic mice. Soyasaponin I, which exhibited lipid peroxidation-inhibitory effects in vitro, inhibited the production of proinflammatory cytokines (TNF-α and IL-1β), inflammatory mediators (NO and PGE2), and inflammatory enzymes (COX-2 and iNOS) in LPS-stimulated peritoneal macrophages. Soyasaponin I also suppressed the phosphorylation of IκB-α and the nuclear translocation of NF-κB. However, these soyasaponins barely inhibited mitogen-activated protein kinases. Oral administration of soyasaponin I (10 and 20 mg/kg) to TNBS-treated colitic mice significantly reduced inflammatory markers, colon length, myeloperoxidase, lipid peroxide (malondialdehyde and 4-hydroxy-2-nonenal), proinflammatory cytokines and NF-κB activation in the colon, as well as increased glutathione content, superoxide dismutase, and catalase activity. Based on these findings, soyasaponin I may attenuate colitis by inhibiting the NF-κB pathway.

Non-peptidyl low molecular weight radical scavenger IAC attenuates DSS-induced colitis in rats

AIM: To investigate the effects of the free radical scavenger bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)decandioate (IAC) in the dextran sodium sulphate (DSS) experimental model of ulcerative colitis.

METHODS: Colitis was induced in Sprague Dawley male rats by administration of 5% DSS in drinking water. IAC (30 mg/kg, lipophilic or hydrophilic form) was administered daily (orally or ip) for 6 d until sacrifice. Colonic damage was assessed by means of indirect (Disease Activity Index score) and direct measures (macroscopic and microscopic scores) and myeloperoxidase (MPO) activity. Neutrophil infiltration within the tissue and glutathione S-transferase activity were also investigated.

RESULTS: DSS-induced colitis impaired body weight gain and markedly increased all inflammatory parameters. Six-day treatment with lipophilic IAC significantly reduced intestinal damage caused by inflammation, induced a down-regulation in MPO activity (0.72 ± 0.12 and 0.45 ± 0.12 with lipophilic IAC po and ip, respectively, vs 1.10 ± 0.27 in untreated DSS colitis animals) and minimized DSS-induced neutrophil infiltration, while hydrophilic IAC administered orally did not ameliorate DSS-induced damage.

CONCLUSION: These results support the hypothesis that reactive oxygen metabolites contribute to inflammation and that the radical scavenger IAC has therapeutic potential in inflammatory bowel disease.

Evidence for a potential role of metallothioneins in inflammatory bowel diseases

Inflammatory bowel diseases (IBDs) are a group of chronic, relapsing, immune-mediated disorders of the intestine, including Crohn's disease and ulcerative colitis. Recent studies underscore the importance of the damaged epithelial barrier and the dysregulated innate immune system in their pathogenesis. Metallothioneins (MTs) are a family of small proteins with a high and conserved cysteine content that are rapidly upregulated in response to an inflammatory stimulus. Herein, we review the current knowledge regarding the expression and potential role of MTs in IBD. MTs exert a central position in zinc homeostasis, modulate the activation of the transcription factor nuclear factor (NF)-kappaB, and serve as antioxidants. In addition, MTs could be involved in IBD through their antiapoptotic effects or through specific immunomodulating extracellular effects. Reports on MT expression in IBD are contradictory but clearly demonstrate a deviant MT expression supporting the idea that these aberrations in IBD require further clarification.

Absence of stearoyl-CoA desaturase-1 does not promote DSS-induced acute colitis

Absence of stearoyl-CoA desaturase-1 (SCD1) in mice leads to chronic inflammation of the skin and increased susceptibility to atherosclerosis, while also increasing plasma inflammatory markers. A recent report suggested that SCD1 deficiency also increases disease severity in a mouse model of inflammatory bowel disease, induced by dextran sulfate sodium (DSS). However, SCD1-deficient mice are known to consume increased amounts of water, which would also be expected to increase the intake of DSS-treated water. The aim of this study was to determine the effect of SCD1 deficiency on DSS-induced acute colitis with DSS dosing adjusted to account for genotype differences in fluid consumption. Wild-type controls were treated with 3.5% DSS for 5 days to induce moderately severe colitis, while the concentration of DSS given to SCD1-deficient mice was lowered to 2.5% to control for increased fluid consumption. Colonic inflammation was assessed by clinical and histological scoring. Although SCD1-deficient mice consumed a total intake of DSS that was greater than that of wild-type controls, colonic inflammation, colon length and fecal blood were not altered by SCD1-deficiency in DSS-induced colitis, while diarrhea and total weight loss were modestly improved. Despite SCD1 deficiency leading to chronic inflammation of the skin and increased susceptibility to atherosclerosis, it does not accelerate inflammation in the DSS-induced model of acute colitis when DSS intake is controlled. These observations suggest that SCD1 deficiency does not play a significant role in colonic inflammation in this model.

Prohibitin is a novel regulator of antioxidant response that attenuates colonic inflammation in mice

BACKGROUND & AIMS

Increased free radicals and/or impaired antioxidant defenses have been shown to play a pathogenetic role in human and animal models of inflammatory bowel disease. Our previous studies showed that prohibitin (PHB) levels are decreased during colitis and that cultured intestinal epithelial cells overexpressing PHB are protected from oxidative stress. This study investigated the effect of intestinal epithelial cell-specific PHB overexpression on oxidative stress associated with experimental colitis and the potential mechanism by which PHB functions as an antioxidant using PHB transgenic mice.

METHODS

Colitis was induced using 2 established mouse models (Salmonella typhimurium and dextran sodium sulfate) in PHB transgenic mice and wild-type littermates. Oxidative stress was determined by measuring glutathione and protein carbonyl levels in the cecum or colon. Nuclear factor erythroid 2-related factor 2 (Nrf2), a transcriptional regulator of oxidant responses, expression, and activation, was assessed in colon mucosa and cultured intestinal epithelial cells overexpressing PHB.

RESULTS

Cells overexpressing PHB showed sustained Nrf2 nuclear accumulation and DNA binding during oxidant stress. PHB transgenic mice exhibited decreased oxidative stress and colitis and increased Nrf2 messenger RNA expression, nuclear protein translocation, and DNA binding compared with wild-type littermates during colitis.

CONCLUSIONS

These results show that PHB is a regulator of Nrf2 expression in intestinal epithelial cells during oxidative conditions and prevents inflammation-associated oxidative stress and injury through sustained activation of Nrf2. Our data show that PHB is a novel regulator of antioxidants and suggest that restoration of PHB levels represents a potential therapeutic approach in inflammatory bowel disease.

5-Aminosalicylic acid inhibits colitis-associated but not sporadic colorectal neoplasia in a novel conditional Apc mouse model

Genetic predisposition, life-style habits and inflammatory bowel diseases (IBD)-related colitis are a main risk factor for colorectal cancer (CRC). 5-Aminosalicylic acid (5-ASA, mesalazine) is a mainstay therapy in IBD and believed to reduce the risk for developing CRC. We aimed to determine the ability of 5-ASA enemas to inhibit the development of sporadic and colitis-related neoplasia in mice. FabplCre;Apc(15lox/+) mice, which spontaneously develop sporadic colorectal tumours, were treated at 5 weeks of age with 5-ASA or placebo enemas for 3 weeks and examined for colorectal tumourigenesis at 8 weeks of age. Colitis-related tumour development was investigated in these mice by administration of dextran sodium sulphate, inducing intestinal inflammation and accelerating colorectal tumourigenesis, combined with treatment of 5-ASA or placebo enemas during and/or after colitis induction. 5-ASA significantly reduced colitis-accelerated neoplasia development by 50%, from 19.4 +/- 2.7 to 9.4 +/- 2.4 (mean tumour numbers +/- SEM, P = 0.02), in the distal part of the large intestine covered by the enema. 5-ASA was only effective when given during and/or after the intestinal inflammatory period. 5-ASA did not reduce, however, sporadic neoplasia development in the FabplCre;Apc(15lox/+) mice. 5-ASA tended to reduce proliferation of epithelial cells in the colitis-associated colorectal tumours but not in the sporadic colorectal tumours. In conclusion, 5-ASA medication inhibits the development of colitis-associated tumours in FabplCre;Apc(15lox/+) mice when administered during and/or after the induction of inflammation. 5-ASA does not reduce, however, sporadic tumour development in this mouse model.

ROS, Hsp27, and IKKbeta mediate dextran sodium sulfate (DSS) activation of IkappaBa, NFkappaB, and IL-8

BACKGROUND

Dextran sodium sulfate (DSS) is a sulfated polysaccharide that has been very widely used to induce inflammation in experimental models of inflammatory bowel disease in which the effects of pharmacologic and biologic therapies are tested. However, the precise mechanisms by which DSS induces inflammation have not been elucidated.

METHODS

DSS-induced increases in phospho-IkappaBalpha, nuclear NFkappaB (p65), and IL-8 secretion in human colonic epithelial cells in tissue culture are attributable to a reactive oxygen species (ROS)-induced pathway of inflammation, and do not require TLR4, MyD88, or Bcl10, which are associated with the innate immune pathway of NFkappaB-IL-8 activation.

RESULTS

DSS-induced increases were inhibited by the ROS scavengers Tempol and Tiron, were associated with decreased phosphorylation of MAPK12 (p38gamma), MAPK 13 (p38delta), and Hsp27, and required the IkappaB kinase (IKK) signalosome component IKKbeta. In ex vivo colonic tissue from TLR4-deficient mice, or following knockdown of MyD88 or Bcl10 or exposure to an IRAK 1/4 inhibitor, DSS effects were not suppressed. Data demonstrated that DSS activates IkappaBalpha, NFkappaB, and IL-8 through an ROS-Hsp27-IKKbeta-mediated pathway, and not through an innate immune cascade.

CONCLUSIONS

These results suggest that DSS models of inflammation may not be optimal for evaluation of interventions that involve mechanisms of innate immunity.

Intestinal inflammation in rats induces metallothionein in colonic submucosa

The aim of the current study was to determine if induction of metallothionein (MT) via acute or chronic dietary zinc supplementation attenuates intestinal inflammation, and to investigate the relationship with site-specific intestinal MT determined by immunolocalization. Growing rats were assigned to zinc-deficient (ZD), acute zinc-treated (ZT), pair-fed, control or chronic Zn-supplemented (ZS) groups. Half the rats in each dietary group received 5% dextran sulphate sodium (DSS) in their drinking water for 4 days. DSS treatment produced acute intestinal inflammation in the colon only, however, dietary zinc deficiency, acute zinc treatment or chronic zinc supplementation did not alter the severity of ulceration. Serum zinc concentrations were attenuated in the DSS-challenged ZT and ZS groups suggesting that zinc was being utilized in some capacity in response to inflammation. DSS-challenge induced MT immunostaining in the colonic submucosa, however, MT was not associated with histological improvements in the present study. The site-specific MT induction in colonic submucosa during intestinal inflammation requires further clarification as a component of the host defense.

G protein-coupled receptor kinase 6 controls post-inflammatory visceral hyperalgesia

Post-inflammatory pain is a poorly understood phenomenon. G protein-coupled receptors are involved in regulating pain signaling in the context of inflammation. G protein-coupled receptor kinases (GRK) modulate signaling through these receptors. We investigated whether GRK6 contributes to post-inflammatory visceral hyperalgesia. Colitis was induced in female mice by 1% dextran sodium sulphate in drinking water for 7 days. Disease score, colon length, and colonic cytokines were determined. On day 49, when animals had recovered from colitis, we induced visceral pain by intracolonic capsaicin instillation. Behavioral responses to capsaicin were monitored for 20 min. Referred hyperalgesia was measured using von Frey hairs. Spinal cord c-Fos was visualized by immunohistochemistry. In contrast to our earlier observations in male GRK6-/- and wild type (WT) mice, we did not detect differences in the course of colitis or in expression of colonic cytokines between female GRK6-/- and WT mice. After recovery from colitis, capsaicin-induced behavioral pain responses and spinal cord c-Fos expression were more pronounced in female GRK6-/- than WT mice. Naive GRK6-/- and WT animals did not differ in pain and c-Fos responses to capsaicin. Capsaicin-induced referred hyperalgesia post-colitis was increased in GRK6-/- compared to WT mice. However, referred hyperalgesia post-colitis was not affected by ablation of GRK6. Furthermore, in vitro IL-1beta sensitized the capsaicin receptor TRPV1 and this process was inhibited by over-expression of GRK6. We describe the novel concept that GRK6 inhibits post-inflammatory visceral hyperalgesia but does not contribute to visceral pain in naive animals. We propose that GRK6 regulates inflammation-induced sensitization of TRPV1.

Therapeutic effect of lecithinized superoxide dismutase against colitis

Ulcerative colitis (UC) involves intestinal mucosal damage induced by reactive oxygen species (ROS), in particular, superoxide anion. Superoxide dismutase (SOD) catalyzes dismutation of superoxide anion to hydrogen peroxide, which is subsequently detoxified by catalase. Lecithinized SOD (PC-SOD) is a new modified form of SOD that has overcome previous clinical limitations of SOD. In this study, we examined the action of PC-SOD using an animal model of UC, dextran sulfate sodium (DSS)-induced colitis. DSS-induced colitis was ameliorated by daily intravenous administration of PC-SOD. Unmodified SOD produced a similar effect but only at more than 30 times the concentration of PC-SOD. In vivo electron spin resonance analysis confirmed that the increase in the colonic level of ROS associated with development of colitis was suppressed by PC-SOD administration. The dose-response profile of PC-SOD was bell-shaped, but simultaneous administration of catalase restored the ameliorative effect at high doses of PC-SOD. Accumulation of hydrogen peroxide was observed with the administration of high doses of PC-SOD, an effect that was suppressed by the simultaneous administration of catalase. We also found that either a weekly intravenous administration or daily oral administration of PC-SOD conferred protection. These results suggest that PC-SOD achieves its ameliorative effect against colitis through decreasing the colonic level of ROS and that its ineffectiveness at higher doses is because of the accumulation of hydrogen peroxide. Furthermore, we consider that intermittent or oral administration of PC-SOD can be applied clinically to improve the quality of life of UC patients.

Oxidative stress in ulcerative colitis-associated carcinogenesis

Oxidative stress is defined as an imbalance between generation of reactive oxygen species (ROS) and decreased antioxidant defense systems. Oxidative stress develops particularly in inflammatory reactions because the inflammatory cells, neutrophils, and macrophages produce large amounts of ROS. It has been known for a long time that oxidative stress in inflamed tissue can pave the way for malignant tumors, and that it is a major pathogenetic factor for the well-established correlation between inflammatory diseases and cancer. Oxidative stress has long been associated with the pathogenesis of chronic inflammatory bowel disease (IBD)-related colorectal cancer. This article provides an overview of the pathology of ROS and presents recent advances concerning the role of ROS in IBD-related colorectal carcinogenesis (Fig. 1).

Oral administration of a catalase-producing Lactococcus lactis can prevent a chemically induced colon cancer in mice

Reactive oxygen species, such as hydrogen peroxide (H2O2), are involved in various aspects of tumour development. Decreasing their levels can therefore be a promising approach for colon cancer prevention. The objective of this study was to evaluate the effect of catalase-producing Lactococcus lactis on the prevention of an experimental murine 1,2-dimethylhydrazine (DMH)-induced colon cancer. DMH-treated BALB/c mice received either a catalase-producing L. lactis strain or the isogenic non-catalase-producing strain as a control, whereas other untreated mice did not receive bacterial supplementation. Catalase activity and H2O2 levels in intestinal fluids and blood samples were measured, and changes in the histology of the large intestines during tumour progression were evaluated. The catalase-producing L. lactis strain used in this study was able to slightly increase catalase activities in DMH-treated mice (1.19+/-0.08 U ml(-1)) and reduce H2O2 levels (3.4+/-1.1 microM) compared to (i) animals that received the non-catalase-producing strain (1.00+/-0.09 U ml(-1), 9.0+/-0.8 microM), and (ii) those that did not receive bacterial supplementation (1.06+/-0.07 U ml(-1), 10.0+/-1.1 microM). Using the histopathological grading scale of chemically induced colorectal cancer, animals that received the catalase-producing L. lactis had a significantly lesser extent of colonic damage and inflammation (2.0+/-0.4) compared to animals that received the non-catalase-producing L. lactis (4.0+/-0.3) or those that did not receive bacterial supplementation (4.7+/-0.5). The catalase-producing L. lactis strain used in this study was able to prevent tumour appearance in an experimental DMH-induced colon cancer model.

Anti-inflammatory properties of Lactobacillus gasseri expressing manganese superoxide dismutase using the interleukin 10-deficient mouse model of colitis

Emerging evidence has implicated reactive oxygen species (ROS) in the pathogenesis of inflammatory bowel disease (IBD). Although intestinal epithelial cells produce the ROS-neutralizing enzyme superoxide dismutase (SOD), the protein and activity levels of copper/zinc (Cu/Zn) and manganese (Mn) SOD are perturbed in inflamed tissues of IBD patients. Thus we investigated the ability of MnSOD from Streptococcus thermophilus to reduce colitis symptoms in interleukin (IL) 10-deficient mice using Lactobacillus gasseri as a delivery vehicle. Cohorts of 13-15 IL-10-deficient mice were left untreated or supplemented with native L. gasseri or L. gasseri expressing MnSOD for 4 wk. Colonic tissue was collected and inflammation was histologically scored. The presence of innate immune cells was investigated by immunohistochemistry and the host antioxidant response was determined by quantitative PCR. It was demonstrated that L. gasseri was stably maintained in mice for at least 3 days. L. gasseri producing MnSOD significantly reduced inflammation in IL-10-deficient mice compared with untreated controls (P < 0.05), whereas the anti-inflammatory effects of both native and MnSOD producing L. gasseri were more pronounced in males. The anti-inflammatory effects of L. gasseri were associated with a reduction in the infiltration of neutrophils and macrophages. Transcripts of antioxidant genes were equivalent in colonic tissues obtained from control and probiotic-treated IL-10-deficient mice. This study demonstrates that L. gasseri producing MnSOD has significant anti-inflammatory activity that reduces the severity of colitis in the IL-10-deficient mouse.

The role of zinc and metallothionein in the dextran sulfate sodium-induced colitis mouse model

Zinc (Zn) and its binding protein metallothionein (MT) have been proposed to suppress the disease activity in ulcerative colitis. To determine the role of Zn and MT in the dextran sulfate sodium (DSS)-induced model of colitis in mice, a DSS dose-response study was conducted in male C57BL/6 wild-type (MT+/+) and MT-null (MT-/-) mice by supplementing 2%, 3%, and 4% DSS in the drinking water for 6 days. In the intervention study, colitis was induced with 2% DSS, Zn (24 mg/ml as ZnO) was gavaged (0.1 ml) daily, concurrent with DSS administration, and the disease activity index (DAI) was scored daily. Histology, MT levels, and myeloperoxidase (MPO) activity were determined. DAI was increased (P<0.05) by 16% and 21% with 3% and 4% concentrations of DSS, respectively, compared to 2%, evident after 5 days of DSS administration. MPO activity was increased in MT+/+ compared to MT-/- mice and those receiving DSS. Zn administration had a 50% (P<0.05) lower DAI compared to DSS alone. Zn partially prevented the distal colon of MT+/+ by 47% from DSS-induced damage compared to MT-/- mice. MT did not prevent DSS-induced colitis and Zn was partially effective in amelioration of DSS-induced colitis.

Anti-inflammatory effects of Lactobacillus casei BL23 producing or not a manganese-dependant catalase on DSS-induced colitis in mice

Background

Human immune cells generate large amounts of reactive oxygen species (ROS) throughout the respiratory burst that occurs during inflammation. In inflammatory bowel diseases, a sustained and abnormal activation of the immune system results in oxidative stress in the digestive tract and in a loss of intestinal homeostasis. We previously showed that the heterologous production of the Lactobacillus plantarum ATCC14431 manganese-dependant catalase (MnKat) in Lb. casei BL23 successfully enhances its survival when exposed to oxidative stress. In this study, we evaluated the preventive effects of this antioxidative Lb. casei strain in a murine model of dextran sodium sulfate (DSS)-induced moderate colitis.

Results

Either Lb. casei BL23 MnKat^- or MnKat⁺ was administered daily to mice treated with DSS for 10 days. In contrast to control mice treated with PBS for which DSS induced bleeding diarrhea and mucosal lesions, mice treated with both Lb. casei strains presented a significant (p < 0.05) reduction of caecal and colonic inflammatory scores.

Conclusion

No contribution of MnKat to the protective effect from epithelial damage has been observed in the tested conditions. In contrast, these results confirm the high interest of Lb. casei as an anti-inflammatory probiotic strain.

Imbalance of the antioxidant network of mouse small intestinal mucosa after radiation exposure

The aim of this study was to investigate acute variations in antioxidant defense systems in the intestinal mucosa after abdominal radiation exposure and the role played by radiation-induced inflammation in these variations. Antioxidant defense systems of mouse small intestinal mucosa were studied at 6 h and 4 days after abdominal radiation exposure. Superoxide dismutases, glutathione peroxidases, catalase, metallothioneins and thioredoxins were followed in terms of mRNA expression, protein expression and enzyme activities. Dexamethasone was administered to investigate the relationship between variations in mucosal antioxidant capacity and radiation-induced inflammation. Six hours after exposure, only mitochondrial-associated antioxidant systems were induced (the superoxide dismutase and thioredoxin 2). Four days after exposure, during the inflammatory phase, superoxide dismutases were decreased and modulations of the second line of the antioxidant network were also observed: Catalase was decreased and glutathione peroxidases and metallothioneins were induced. Dexamethasone treatment modulated only glutathione peroxidase expression and did not influence either metallothionein or superoxide dismutase expression. Our findings provide direct in vivo evidence that antioxidant mechanisms of the small intestinal mucosa were not markedly mobilized during the very acute tissue radiation response. During the radiation-induced acute inflammatory response, the antioxidant capacity appeared to be dependent on inflammatory status to a certain extent.

Propofol attenuates intestinal mucosa injury induced by intestinal ischemia-reperfusion in the rat

PURPOSE

We investigated whether propofol at a sedative dose can prevent intestinal mucosa ischemia/reperfusion (I/R) injury, and if propofol can attenuate oxidative stress and increases in nitric oxide (NO) and endothelin-1 (ET-1) release that may occur during intestinal I/R injury.

METHODS

Rats were randomly allocated into one of five groups (n=10 each): (i) sham control; (ii) injury (one hour superior mesenteric artery occlusion followed by three hours reperfusion); (iii) propofol pre-treatment, with propofol given 30 min before inducing intestinal ischemia; (iv) simultaneous propofol treatment, with propofol given 30 min before intestinal reperfusion was started; (v) propofol post-treatment, with propofol given 30 min after intestinal reperfusion was initiated. In the treatment groups, propofol 50 mg x kg(-1) was administrated intraperitoneally. Animals in the control and untreated injury groups received equal volumes of intralipid (the vehicle solution of propofol) intraperitoneally. Intestinal mucosa histology was analyzed by Chiu's scoring assessment. Levels of lactic acid (LD), NO, ET-1, lipid peroxidation product malondialdehyde (MDA) and superoxide dismutase (SOD) activity in intestinal mucosa were determined.

RESULTS

Histological results showed severe damage in the intestinal mucosa of the injury group accompanied by increases in MDA, NO and ET-1 and a decrease in SOD activity. Propofol treatments, especially pre-treatment, significantly reduced Chiu's scores and levels of MDA, NO, ET-1 and LD, while restoring SOD activity.

CONCLUSION

These findings indicate that propofol attenuates intestinal I/R-induced mucosal injury in an animal model. The response may be attributable to propofol's antioxidant properties, and the effects of inhibiting over-production of NO and in decreasing ET-1 levels.