Protective effects of M40403, a superoxide dismutase mimetic, in a rodent model of colitis

Antioxidative Stress-Induced Destruction to Cochlear Cells Caused by Blind Antioxidant Therapy

OBJECTIVE

Verification that blind and excessive use of antioxidants leads to antioxidant stress which exacerbates cochlear cell damage.

STUDY DESIGN

Basic research.

SETTING

The Third Affiliated Hospital of Sun Yat-Sen University.

METHODS

We compared and quantified hair cell-like house ear institute-organ of corti 1 (HEI-OC1) cell density, cell viability, and apoptosis caused by different concentrations of N-acetylcysteine (NAC) via Hoechst staining, Cell Counting Kit 8, Hoechst with propidium iodide staining, and Annexin V with propidium iodide (PI) staining. Apoptosis induced by high concentrations of M40403 and coenzyme Q10 in cochlear explants was analyzed and compared by cochlear dissection and activated caspase 3 labeling.

RESULTS

With the increase of NAC concentration (0-1000 μmol/L), cell density decreased consequently and reached the lowest at 1000 μmol/L (****P ≤ .0001). Cell viability is also declining (**P < .01). The number of Annexin V-fluorescein isothiocyanate-labeled cells and PI-labeled cells increased with increasing NAC concentration after treatment of HEI-OC1 cells for 48 hours. The proportion of apoptotic cells also rose (*P < .05, **P < .01). Cochlear hair cells (HCs) treated with low concentrations of M40403 and coenzyme Q10 for 48 hours showed no damage. When the concentrations of M40403 and coenzyme Q10 were increased (concentrations＞30 μmol/L), HC damage began, followed by a dose-dependent increase in HC loss (*P < .001, **P < .0001). Activated caspase-3 was clearly apparent in cochlear explants treated with 50 μmol/L M40403 and coenzyme Q10 compared with cochlear explants without added M40403 and coenzyme Q10.

CONCLUSION

These experimental results suggest that inappropriate application of antioxidants can cause severe damage to normal cochlear HCs.

Active nanoparticle targeting of MUC5AC ameliorates therapeutic outcome in experimental colitis

Inflammatory bowel diseases (IBDs), which include Crohn's disease (CD) and ulcerative colitis (UC), are chronic inflammatory diseases of the gastrointestinal tract and are characterized by chronic recurrent ulceration of the bowels. Colon-targeted drug delivery systems (DDS) have received significant attention for their potential to treat IBD by improving the inflamed tissue selectivity. Herein, antiMUC5AC-decorated drug loaded nanoparticles (NP) are suggested for active epithelial targeting and selective adhesion to the inflamed tissue in experimental colitis. NPs conjugated with antiMUC5AC (anti-MUC5) were tested for their degree of bioadhesion with HT29-MTX cells by comparison with non-targeted BSA-NP conjugates. In vivo, the selectivity of bioadhesion and the influence of ligand density in bioadhesion efficiency as well as the therapeutic benefit for glucocorticoid loaded anti-MUC5-NP were studied in a murine colitis model. Quantitative adhesion analyses showed that anti-MUC5-conjugated NP exhibited a much higher binding and selectivity to inflamed tissue compared to PNA-, IgG1- and BSA-NP conjugates used as controls. This bioadhesion efficiency was found to be dependent on the ligand density, present at the NP surface. The binding specificity between anti-MUC5 ligand and inflamed tissues was confirmed by fluorescence imaging. Both anti-MUC5-NP and all other glucocorticoid containing formulations led to a significant mitigation of the experimental colitis, as became evident from the substantial reduction of myeloperoxidase activity and pro-inflammatory cytokine concentrations (TNF-α, IL-1β). Targeted NP by using anti-MUC5 appears to be a very promising tool in future treatment of various types of local disorders affecting the gastro-intestinal tract but not limited to colitis.

Peroxisome Proliferator–Activated Receptor-α: A Pivotal Regulator of the Gastrointestinal Tract

Peroxisome proliferator–activated receptor (PPAR)-α is a ligand-activated transcription factor distributed in various tissues and cells. It regulates lipid metabolism and plays vital roles in the pathology of the cardiovascular system. However, its roles in the gastrointestinal tract (GIT) are relatively less known. In this review, after summarizing the expression profile of PPAR-α in the GIT, we analyzed its functions in the GIT, including physiological control of the lipid metabolism and pathologic mediation in the progress of inflammation. The mechanism of this regulation could be achieved via interactions with gut microbes and further impact the maintenance of body circadian rhythms and the secretion of nitric oxide. These are also targets of PPAR-α and are well-described in this review. In addition, we also highlighted the potential use of PPAR-α in treating GIT diseases and the inadequacy of clinical trials in this field.

The Superoxide Dismutase Mimetic M40403, Improves 5-Fluorouracil-induced Small Intestinal Mucositis in a Mouse Model

BACKGROUND/AIM

Intestinal mucositis with diarrhea is a dose-limiting toxicity of 5-fluorouracil (5-FU). M40403, a superoxide dismutase mimetic, was evaluated on whether it improves the mucositis with diarrhea.

MATERIALS AND METHODS

BALB/c mice were treated with daily intraperitoneal injections of 5-FU±M40403 for five consecutive days. Following treatment, light microscopy (apoptosis), electron microscopy (autophagy), and analyses for the expression of apoptosis/autophagy-related proteins were performed in analysing small intestinal samples. Body weight, diarrhea score, blood cytokine levels, complete blood count, and blood chemistries were measured. The in vivo anti-tumor activity of 5-FU±M40403 was also evaluated.

RESULTS

M40403 improved 5-FU-induced intestinal mucositis (apoptosis and autophagy) and attenuated 5-FU-induced changes in the expression of apoptosis/autophagy-related proteins, weight loss, diarrhea score, and serum TNF-α levels. M40403 neither added further adverse effects nor compromised the anti-tumor activity during 5-FU treatment.

CONCLUSION

M40403 can be useful in improving 5-FU-induced intestinal mucositis with diarrhea.

Superoxide Dismutase as an Intervention for Radiation Therapy-Associated Toxicities: Review and Profile of Avasopasem Manganese as a Treatment Option for Radiation-Induced Mucositis

Toxicities associated with radiation therapy are common, symptomatically devastating, and costly. The best chance to effectively mitigate radiation-associated normal tissue side effects are interventions aimed at disrupting the biological cascade, which is the basis for toxicity development, while simultaneously not reducing the beneficial impact of radiation on tumor. Oxidative stress is a key initiator of radiation-associated normal tissue injury as physiologic antioxidant mechanisms are overwhelmed by the accumulation of effects produced by fractionated treatment regimens. And fundamental to this is the generation of superoxide, which is normally removed by superoxide dismutases (SODs). Attempts to supplement the activity of endogenous SOD to prevent radiation-induced normal tissue injury have included the administration of bovine-derived SOD and increasing SOD production using gene transfer, neither of which has resulted in a clinically acceptable therapy. A third approach has been to develop synthetic small molecule dismutase mimetics. This approach has led to the creation and development of avasopasem manganese, a unique and specific dismutase mimetic that, in clinical trials, has shown promising potential to reduce the incidence, severity and duration of severe oral mucositis amongst patients being treated with concomitant chemoradiation for cancers of the head and neck. Further, avasopasem and related analogues have demonstrated mechanism-related antitumor synergy in combination with high dose per fraction radiotherapy, an observation that is also being tested in clinical trials. An ongoing Phase 3 trial seeks to confirm avasopasem manganese as an effective intervention for severe oral mucositis associated with chemoradiation in head and neck cancer patients.

Anti-Inflammatory Potential Exhibited by Amomum subulatum Fruits Mitigates Experimentally Induced Acute and Chronic Inflammation in Mice: Evaluation of Antioxidant Parameters, Pro-Inflammatory Mediators and HO-1 Pathway

OBJECTIVE

Conventional anti-inflammatory drugs are associated with serious adverse effects which bring about an ever-increasing demand to supersede them with natural and safe anti-inflammatory agents. Hence, the prime objective of this study was to evaluate the anti- inflammatory potential of an underutilized culinary spice "Amomum subulatum".

METHODS

To assess anti-inflammatory activity of MEAS, acute and chronic inflammation studies were carried out in carrageenan and formalin induced mice paw edema models respectively. Paw volume was measured by vernier caliper. Status of antioxidant enzymes and oxidative stress markers were determined in paw tissue homogenates following standard protocols. Histopathology and immunohistochemistry analysis of paw tissue samples were also performed. Levels of proinflammatory cytokines in serum were quantified by ELISA. Effect of MEAS on vascular permeability was evaluated by evans blue dye extravasation assay. Involvement of heme oxygenase (HO)-1 pathway in anti-inflammatory action of MEAS was investigated by pretreating mice with zinc protoporphyrin (ZnPP) IX, a specific inhibitor of HO-1.

RESULTS

MEAS administration significantly reduced paw edema, as evidenced by paw volume measurement and histopathology analysis. Additionally, pretreatment with MEAS markedly reduced vascular permeability, serum proinflammatory cytokine levels, cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). Further, the anti-inflammatory mechanism of MEAS showed the involvement of HO-1 pathway when HO-1 was inhibited by ZnPPIX.

CONCLUSION

Our results manifested strong anti-inflammatory activity of MEAS, suggesting its potential use as a therapeutic alternative for treating inflammatory disorders.

Fruit Extract of Pithecellobium dulce (FPD) ameliorates carrageenan-induced acute inflammatory responses via regulating pro-inflammatory mediators

Unravelling the precise mechanisms underlying the anti-inflammatory action of fruit extract of Pithecellobium dulce (FPD) is quite complex. Hence the prime approach of this particular study is to unveil intriguing insights to its possible anti-inflammatory mechanisms. Anti-inflammatory effects of FPD were determined against experimentally induced acute and chronic inflammation in mice paw edema models. Administration of FPD significantly reduced the acute and chronic inflammation via regulating pro-inflammatory mediators such as pro-inflammatory cytokines (TNF-α, IL-6, and IL-1ß), Cycloxygenase 2 (COX-2), and inducible nitric oxide synthase (iNOS) compared to control group. The overall results suggest that FPD mitigates inflammation by regulating the inflammatory mediators. PRACTICAL APPLICATIONS: Fruit of Pithecellobium dulce is comestible and has been widely distributed in Asian pacific region. Non-steroidal anti-inflammatory drugs (NSAIDS) are among the most conventional treatment strategy against pain and inflammation. Although, chronic use of NSAIDS are associated with severe side effects such as gastrointestinal irritation, hepatic injury, excessive bleeding, and cardiovascular disorders. Hence identification of more effective complementary and alternative therapeutic approach from natural resources with fewer side effects could improve the quality of life of those receiving NSAIDS. Administration of fruit extract of Pithecellobium dulce ameliorates carrageenan-induced acute inflammatory responses, as evidenced by paw edema measurement, expression of antioxidant enzymes such as glutathionine, super oxide dismutase, pro-inflammatory cytokine analysis (IL-1β, IL-6, and TNF-α), vascular permeability measurement, expression of COX-2 and iNOS. Further, confirmed the involvement of HO-1 pathway in anti-inflammatory action of FPD. The outcome of this present investigation could have a broad range of applications in alleviating inflammatory disorders.

Stability Profiles and Therapeutic Effect of Cu/Zn Superoxide Dismutase Chemically Coupled to O-Quaternary Chitosan Derivatives against Dextran Sodium Sulfate-Induced Colitis

Superoxide dismutase (SOD) has attracted considerable attention on treatment of reactive oxygen species (ROS)-related disorders. We previously conjugated Cu/Zn SOD to O-quaternary chitosan derivatives (O-HTCC) to yield a polymer–enzyme conjugate O-HTCC-SOD that demonstrated superior therapeutic effect to native SOD. The present study demonstrated that O-HTCC-SOD had wider pH activity range, better thermal stability, excellent long-term stability for storage, as well as unique reinstatement of activity exposure to proteolytic degradation that was helpful for longer half-life in vivo. O-HTCC-SOD exerted significant anti-inflammatory effects on lipopolysaccharides (LPS)-stimulated mouse peritoneal macrophages by down-regulating production of pro-inflammatory cytokines and intracellular ROS. O-HTCC-SOD significantly attenuated dextran sodium (DSS)-induced colitis in mice as observed by the colitis severity, neutrophil infiltration and histopathological damage, whereas native SOD failed to do so. In conclusion, conjugation of O-HTCC conferred SOD with better stability and enhanced therapeutic potential, offering a promising option in treatment of inflammatory bowel disease.

A Cell-Penetrant Manganese Superoxide Dismutase (MnSOD) Mimic Is Able To Complement MnSOD and Exerts an Antiinflammatory Effect on Cellular and Animal Models of Inflammatory Bowel Diseases

Inorganic complexes are increasingly used for biological and medicinal applications, and the question of the cell penetration and distribution of metallodrugs is key to understanding their biological activity. Oxidative stress is known to be involved in inflammation and in inflammatory bowel diseases for which antioxidative defenses are weakened. We report here the study of the manganese complex Mn1 mimicking superoxide dismutase (SOD), a protein involved in cell protection against oxidative stress, using an approach in inorganic cellular chemistry combining the investigation of Mn1 intracellular speciation using mass spectrometry and of its quantification and distribution using electron paramagnetic resonance and spatially resolved X-ray fluorescence with evaluation of its biological activity. More precisely, we have looked for and found the MS signature of Mn1 in cell lysates and quantified the overall manganese content. Intestinal epithelial cells activated by bacterial lipopolysaccharide were taken as a cellular model of oxidative stress and inflammation. DNBS-induced colitis in mice was used to investigate Mn1 activity in vivo. Mn1 exerts an intracellular antiinflammatory activity, remains at least partially coordinated, with diffuse distribution over the whole cell, and functionally complements mitochondrial MnSOD.

The anti-inflammatory and antioxidant effects of bergamot juice extract (BJe) in an experimental model of inflammatory bowel disease

BACKGROUND & AIMS

The beneficial properties of the flavonoid fraction of bergamot juice (BJe) have been raising interest and have been the subject of recent studies, considering the potentiality of its health promoting substances. Flavonoids have demonstrated radical-scavenging and anti-inflammatory activities. The aim of the present study was to examine the effects of BJe in mice subjected to experimental colitis.

METHODS

Colitis was induced in mice by intracolonic instillation of dinitrobenzene sulfonic acid (DNBS). BJe was administered daily orally (at 5, 10 and 20 mg/kg).

RESULTS

Four days after DNBS administration, colon nuclear factor NF-κB translocation and MAP kinase phospho-JNK activation were increased as well as cytokine production such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β. Neutrophil infiltration, by myeloperoxidase (MPO) activity, in the mucosa was associated with up-regulation of adhesion molecules (ICAM-1 and P-selectin). Immunohistochemistry for nitrotyrosine and poly ADP-ribose (PAR) also showed an intense staining in the inflamed colon. Treatment with BJe decreased the appearance of diarrhea and body weight loss. This was associated with a reduction in colonic MPO activity. BJe reduced nuclear NF-κB translocation, p-JNK activation, the pro-inflammatory cytokines release, the appearance of nitrotyrosine and PAR in the colon and reduced the up-regulation of ICAM-1 and P-selectin. In addition, colon inflammation was also associated with apoptotic damage. Treatment with BJe caused a decrease of pro-apoptotic Bax expression and an increase of anti-apoptotic Bcl-2 expression.

CONCLUSIONS

The results of this study suggested that administration of BJe induced, partly specified, anti-inflammatory mechanisms, which potentially may be beneficial for the treatment of IBD in humans.

Biomarkers of antioxidant status, inflammation, and cartilage metabolism are affected by acute intense exercise but not superoxide dismutase supplementation in horses

Objectives were to evaluate effects of (1) repetitive arthrocentesis on biomarkers of inflammation (prostaglandin E(2), PGE(2)) and aggrecan synthesis (chondroitin sulfate-846; CS) in synovial fluid (SF); (2) exercise and superoxide dismutase (SOD) supplementation on biomarkers of inflammation, antioxidant status, and aggrecan synthesis, in horses. Preliminary trial. Standardbreds underwent four arthrocentesis procedures within 48 h and exhibited elevated CS and no changes in PGE(2). Exercise trial. this randomized crossover design used twelve Standardbred mares which received either treatment (3000 IU d(-1) oral SOD powder) or placebo (cellulose powder) for 6 wks which culminated with them running a repeated sprint exercise test (RSET). Samples were collected before (PRE), during (PEAK), and following exercise (POST). Exercise resulted in increased (P < 0.05) antioxidant defenses including erythrocyte SOD, total glutathione, glutathione peroxidase, gene transcripts for interferon-gamma, interleukin-10, and interleukin-1β in blood, and decreased plasma nitric oxide. Exercise increased (P < 0.05) SF CS and adjusted-PGE(2), and higher (P < 0.05) CS and PGE(2) were found in hock versus carpus joints. No treatment effects were detected. Results suggest normal adaptive responses likely due to exercise-induced tissue microdamage and oxidative stress. Additional research is needed to identify benefit(s) of SOD supplementation in horses.

Treatment of inflammatory bowel disease (IBD)

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract, which includes Crohn's disease (CD) and ulcerative colitis (UC). These diseases have become important health problems. Medical therapy for IBD has advanced dramatically in the last decade with the introduction of targeted biologic therapies, the optimization of older therapies, including rugs such as immunomodulators and 5-aminosalicylic acid (5-ASA), and a better understanding of the mucosal immune system and the genetics involved in the pathogenesis of IBD. The goal of IBD therapy is to induce and maintain remission. The current treatment paradigm involves a step-up approach, moving to aggressive, powerful therapies only when milder therapies with fewer potential side effects fail or when patients declare themselves to have an aggressive disease. This review focuses on the current treatments for inflammatory bowel disease.

Natural almond skin reduced oxidative stress and inflammation in an experimental model of inflammatory bowel disease

The aim of the present study was to examine the effects of natural almond skin (NS) powder in mice subjected to experimental colitis. Colitis was induced in mice by intracolonic instillation of dinitrobenzene sulfonic acid (DNBS). NS powder was administered daily orally (30 mg/kg). Four days after DNBS administration, colon NF-κB and p-JNK activation was increased as well as TNF-α and IL-1β productions. Neutrophil infiltration, by myeloperoxidase (MPO) activity, in the mucosa was associated with up-regulation of ICAM-1 and P-selectin. Immunohistochemistry for i-NOS, nitrotyrosine and poly (ADP-ribose) polymerase (PARP) showed an intense staining in the inflamed colon. Treatment with NS powder significantly reduced the appearance of diarrhea and body weight loss. This was associated with a significant reduction in colonic MPO activity. NS powder also reduced NF-κB and p-JNK activation, the pro-inflammatory cytokines release, the appearance of i-NOS, nitrotyrosine and PARP in the colon and reduced the up-regulation of ICAM-1 and the expression of P-selectin. The results of this study suggested that administration of NS powder may be beneficial for treatment of inflammatory bowel disease.

Superoxide dismutase mimics: chemistry, pharmacology, and therapeutic potential

Oxidative stress has become widely viewed as an underlying condition in a number of diseases, such as ischemia-reperfusion disorders, central nervous system disorders, cardiovascular conditions, cancer, and diabetes. Thus, natural and synthetic antioxidants have been actively sought. Superoxide dismutase is a first line of defense against oxidative stress under physiological and pathological conditions. Therefore, the development of therapeutics aimed at mimicking superoxide dismutase was a natural maneuver. Metalloporphyrins, as well as Mn cyclic polyamines, Mn salen derivatives and nitroxides were all originally developed as SOD mimics. The same thermodynamic and electrostatic properties that make them potent SOD mimics may allow them to reduce other reactive species such as peroxynitrite, peroxynitrite-derived CO(3)(*-), peroxyl radical, and less efficiently H(2)O(2). By doing so SOD mimics can decrease both primary and secondary oxidative events, the latter arising from the inhibition of cellular transcriptional activity. To better judge the therapeutic potential and the advantage of one over the other type of compound, comparative studies of different classes of drugs in the same cellular and/or animal models are needed. We here provide a comprehensive overview of the chemical properties and some in vivo effects observed with various classes of compounds with a special emphasis on porphyrin-based compounds.

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.

Inhibition of tumor necrosis factor and nitrosative/oxidative stresses by Ziziphora clinopoides (Kahlioti); a molecular mechanism of protection against dextran sodium sulfate-induced colitis in mice

Inflammatory bowel disease (IBD) is a chronic condition of the intestine with unknown etiology involving multiple immune genetic and environmental factors. The authors were interested in examining the protective effect of Ziziphora clinopoides methanolic extract, an Iranian folk herbal medicine, on inflammatory mediators in experimental colitis. Colitis in NMRI mice was induced by oral administration of dextran sodium sulfate (DSS, 3%). Z. clinopoides was administrated orally at doses of 75, 150, and 300 mg/kg/day for 7 days. The level of lipid peroxidation (LP), total antioxidant capacity (TAC), total thiol molecules (TTM), antioxidant enzymes including superoxide dismutase (SOD) and catalase (CAT), and nitric oxide (NO) as a marker of nitrosative stress, and tumor necrosis factor alpha (TNF-alpha) as a mediator of inflammation and apoptosis were measured in the colon homogenate. Treatment by DSS increased bowel LP, NO, and TNF-alpha while decreasing TAC, SOD, CAT, and TTM. All measured parameters were improved by Z. clinopoides treatment and reached close to normal levels. The present study further supports the role of oxidative/nitrosative stresses and TNF-alpha in the pathogenesis of colitis and protective effects of this herb. The data are promising for further preclinical studies directed towards understanding mechanism of action and cross-species and cross-model comparisons for potential protective effects.

Role of nitroso radicals as drug targets in circulatory shock

A vast amount of circumstantial evidence implicates oxygen-derived free radicals (especially, superoxide and hydroxyl radical) and high-energy oxidants [such as peroxynitrite (OONO(-))] as mediators of shock and ischaemia/reperfusion injury. Reactive oxygen species can initiate a wide range of toxic oxidative reactions. These include initiation of lipid peroxidation, direct inhibition of mitochondrial respiratory chain enzymes, inactivation of glyceraldehyde-3 phosphate dehydrogenase, inhibition of membrane sodium/potassium adenosine 5'-triphosphate-ase activity, inactivation of membrane sodium channels and other oxidative modifications of proteins. All these toxicities are likely to play a role in the pathophysiology of shock and ischaemia and reperfusion. Moreover, various studies have clearly shown that treatment with either OONO(-) decomposition catalysts, which selectively inhibit OONO(-), or with superoxide dismutase (SOD) mimetics, which selectively mimic the catalytic activity of the human SOD enzymes, have been shown to prevent in vivo the delayed vascular decompensation and the cellular energetic failure associated with shock and ischaemia/reperfusion injury.

Green tea polyphenol extract attenuates colon injury induced by experimental colitis

Inflammatory bowel disease (IBD) is characterised by oxidative and nitrosative stress, leukocyte infiltration, and up-regulation of intercellular adhesion molecule 1 (ICAM-1) expression in the colon. The aim of the present study was to examine the effects of green tea extract in rats subjected to experimental colitis induced by intracolonic instillation of dinitrobenzene sulphonic acid (DNBS). At 4 days after DNBS administration the rats were sacrificed. Treatment with green tea extract significantly attenuated diarrhoea and loss of body weight. This was associated with a remarkable amelioration of the disruption of the colonic architecture, significant reduction of colonic myeloperoxidase (MPO) and tumor necrosis factor-alpha (TNF-alpha) production. Green tea extract also reduced the appearance of nitrotyrosine immunoreactivity in the colon and reduced the up-regulation of ICAM-1.

Effects of the non-peptidyl low molecular weight radical scavenger IAC in DNBS-induced colitis in rats

Intestinal inflammation is accompanied by excessive production of reactive oxygen and nitrogen radical species because of the massive infiltration of polymorphonuclear and mononuclear leukocytes. Antioxidant compounds seem to protect against experimental colitis. Here we investigated the effects of the innovative non-peptidyl, low molecular weight radical scavenger bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)decandioate (IAC), which is highly reactive with most oxygen, nitrogen and carbon centred radicals and is easily distributed in cell membranes and intra-extra cellular compartments, in the DNBS model of colitis. Colitis was induced in male SD rats by intrarectal administration of DNBS (15 mg/rat). IAC (30 mg/kg b.w., hydrophilic or lipophilic form) was administered daily (orally or i.p.) starting from the day before the induction of colitis for 7 days (n=6-8 per group). Colonic damage was assessed by means of macroscopic and histological scores, myeloperoxidase activity (MPO) and TNF-alpha tissue levels. Colitis impaired body weight gain and markedly increased all inflammatory parameters. IAC significantly counteracted the reduction in body weight gain, decreased colonic damage and inflammation and TNF-alpha levels in DNBS-colitis. The antioxidant IAC significantly ameliorates experimental colitis in rats. This strengthens the notion that antioxidant compounds may have therapeutic potential in inflammatory bowel disease.

Molecular fingerprints of neutrophil-dependent oxidative stress in inflammatory bowel disease

Neutrophil accumulation within epithelial crypts and in the intestinal mucosa directly correlates with clinical disease activity and epithelial injury in inflammatory bowel disease (IBD). Current advances have defined the mechanisms by which neutrophils are activated or migrate across endothelial and mucosal epithelial cells. A better understanding of this process will likely provide new insights into novel treatment strategies for IBD. Especially, activated neutrophils produce reactive oxygen and nitrogen species and myeloperoxidase within intestinal mucosa, which induce oxidative stress. Posttranslational modification of proteins generated by these reactive species serves as a "molecular fingerprint" of protein modification by lipid peroxidation-, nitric oxide-, and myeloperoxidase-derived oxidants. Measurement of these modified proteins may serve both as a quantitative index of oxidative stress and an important new biological marker of clinical relevance to IBD. We have succeeded in the clinical development of a novel granulocyte adsorptive apheresis therapy for IBD. In this review, we discuss current advances in defining the role of neutrophil-dependent oxidative stress in IBD.

Manganese porphyrin reduces renal injury and mitochondrial damage during ischemia/reperfusion

Renal ischemia/reperfusion (I/R) injury often occurs as a result of vascular surgery, organ procurement, or transplantation. We previously showed that renal I/R results in ATP depletion, oxidant production, and manganese superoxide dismutase (MnSOD) inactivation. There have been several reports that overexpression of MnSOD protects tissues/organs from I/R-related damage, thus a loss of MnSOD activity during I/R likely contributes to tissue injury. The present study examined the therapeutic benefit of a catalytic antioxidant, Mn(III) meso-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin (MnTnHex-2-PyP(5+)), using the rat renal I/R model. This was the first study to examine the effects of MnTnHex-2-PyP(5+) in an animal model of oxidative stress injury. Our results showed that porphyrin pretreatment of rats for 24 h protected against ATP depletion, MnSOD inactivation, nitrotyrosine formation, and renal dysfunction. The dose (50 microg/kg) used in this study is lower than doses of various types of antioxidants commonly used in animal models of oxidative stress injuries. In addition, using novel proteomic techniques, we identified the ATP synthase-beta subunit as a key protein induced by MnTnHex-2-PyP(5+) treatment alone and complex V (ATP synthase) as a target of injury during renal I/R. These results showed that MnTnHex-2-PyP(5+) protected against renal I/R injury via induction of key mitochondrial proteins that may be capable of blunting oxidative injury.

Nitric oxide and peroxynitrite in health and disease

The discovery that mammalian cells have the ability to synthesize the free radical nitric oxide (NO) has stimulated an extraordinary impetus for scientific research in all the fields of biology and medicine. Since its early description as an endothelial-derived relaxing factor, NO has emerged as a fundamental signaling device regulating virtually every critical cellular function, as well as a potent mediator of cellular damage in a wide range of conditions. Recent evidence indicates that most of the cytotoxicity attributed to NO is rather due to peroxynitrite, produced from the diffusion-controlled reaction between NO and another free radical, the superoxide anion. Peroxynitrite interacts with lipids, DNA, and proteins via direct oxidative reactions or via indirect, radical-mediated mechanisms. These reactions trigger cellular responses ranging from subtle modulations of cell signaling to overwhelming oxidative injury, committing cells to necrosis or apoptosis. In vivo, peroxynitrite generation represents a crucial pathogenic mechanism in conditions such as stroke, myocardial infarction, chronic heart failure, diabetes, circulatory shock, chronic inflammatory diseases, cancer, and neurodegenerative disorders. Hence, novel pharmacological strategies aimed at removing peroxynitrite might represent powerful therapeutic tools in the future. Evidence supporting these novel roles of NO and peroxynitrite is presented in detail in this review.

Improvement of an experimental colitis in rats by lactic acid bacteria producing superoxide dismutase

The use of superoxide dismutases (SODs) in inflammatory diseases is hampered by their short circulatory half-life. To determine whether a bacterial supply of SOD into the colon might improve an experimental colitis, the effects of oral treatment with live recombinant lactic acid bacteria producing different amounts of SOD and those of colonic infusion of SOD were compared. Wistar rats were fitted with a catheter in the proximal colon through which TNBS was administered to induce colitis. Animals received a continuous intracolonic infusion of bovine SOD (40 U per rat per day) for 4 days after TNBS or were treated orally with live recombinant Lactococcus lactis or Lactobacillus plantarum strains (10 colony-forming units (CFU)/d), producing or not producing SOD, for 4 days before and after TNBS. SOD activity of bacterial extracts was 0, 26, 74, and 624 units/10 CFU for L. plantarum, L. lactis, L. lactis SOD, and L. plantarum SOD, respectively. Four days after TNBS, macroscopic and microscopic damage, myeloperoxidase (MPO) activity, and nitrotyrosine immunostaining were evaluated. TNBS induced macroscopic and microscopic damages, an increase in MPO activity, and intense immunostaining for nitrotyrosine. Macroscopic damage and MPO activity were reduced by bovine SOD. These parameters and microscopic damages also were reduced by L. lactis, L. lactis SOD, and L. plantarum SOD, but not by L. plantarum. Nitrotyrosine immunostaining was attenuated after treatment with the 4 bacterial strains. Although not all of the anti-inflammatory effects could be attributed directly to SOD, our results suggest that SOD-producing lactic acid bacteria open a novel approach in inflammatory bowel disease treatment.

Melatonin modulates signal transduction pathways and apoptosis in experimental colitis

Various evidences have documented that the pineal secretory product melatonin exerts an important anti-inflammatory effect in different experimental models including colitis. The aim of the present study was to evaluate whether melatonin regulates the inflammatory response of experimental colitis in rats at the level of signal transduction pathway. Colitis was induced by intracolonic instillation of dinitrobenzene sulfonic acid (DNBS). Four days after DNBS administration, a substantial increase of colon TNF-alpha production was associated with the colon damage. In DNBS-treated rats, the colon injury correlated with a significant rise of apoptosis (evaluated by TUNEL coloration) which was associated with a significant increased expression of proapoptotic Bax and decreased colon content of antiapoptotic Bcl-2. This inflammatory response was also related to activation of nuclear factor-kappaB (NF-kappaB) and phosphorylation of c-Jun as well as FAS ligand expression in the colon. Treatment with melatonin (15 mg/kg daily i.p.) was associated with a remarkable amelioration of colonic disrupted architecture as well as a significant reduction of TNF-alpha. Melatonin also reduced the NF-kappaB activation and phosphorylation of c-Jun as well as the Fas ligand expression in the colon. Furthermore, melatonin reduced the expression of Bax and prevented the loss of Bcl-2 proteins as well as the presence of apoptotic cells caused by DNBS. The results of this study show that melatonin administration exerts beneficial effects in inflammatory bowel disease by modulating signal transduction pathways.

ADOA3R as a therapeutic target in experimental colitis: proof by validated high-density oligonucleotide microarray analysis

Adenosine A3 receptors (ADOA3Rs) are emerging as novel purinergic targets for treatment of inflammatory diseases. Our goal was to assess the protective effect of the ADOA3R agonist N(6)-(3-iodobenzyl)-adenosine-5-N-methyluronamide (IB-MECA) on gene dysregulation and injury in a rat chronic model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)--induced colitis. It was necessary to develop and validate a microarray technique for testing the protective effects of purine-based drugs in experimental inflammatory bowel disease. High-density oligonucleotide microarray analysis of gene dysregulation was assessed in colons from normal, TNBS-treated (7 days), and oral IB-MECA-treated rats (1.5 mg/kg b.i.d.) using a rat RNU34 neural GeneChip of 724 genes and SYBR green polymerase chain reaction. Analysis included clinical evaluation, weight loss assessment, and electron paramagnetic resonance imaging/spin-trap monitoring of free radicals. Remarkable colitis-induced gene dysregulation occurs in the most exceptional cluster of 5.4% of the gene pool, revealing 2 modes of colitis-related dysregulation. Downregulation occurs in membrane transporter, mitogen-activated protein (MAP) kinase, and channel genes. Upregulation occurs in chemokine, cytokine/inflammatory, stress, growth factor, intracellular signaling, receptor, heat shock protein, retinoid metabolism, neural, remodeling, and redox-sensitive genes. Oral IB-MECA prevented dysregulation in 92% of these genes, histopathology, gut injury, and weight loss. IB-MECA or adenosine suppressed elevated free radicals in ex vivo inflamed gut. Oral IB-MECA blocked the colitis-induced upregulation (<or=20-fold) of Bzrp, P2X1R, P2X4R, P2X7R, P2Y2R, P2Y6R, and A2aR/A2bR but not A1R or A3R genes or downregulated P2X2R, P2Y1R, and P2Y4R. Real-time SYBR green polymerase chain reaction validated gene chip data for both induction of colitis and treatment with IB-MECA for >90% of genes tested (33 of 37 genes). We conclude that our validated high-density oligonucleotide microarray analysis is a powerful technique for molecular gene dysregulation studies to assess the beneficial effects of purine-based or other drugs in experimental colitis. ADOA3R is new potential therapeutic target for inflammatory bowel disease.

Antagonizing reactive oxygen by treatment with a manganese (III) metalloporphyrin-based superoxide dismutase mimetic in cardiac transplants

OBJECTIVE

Oxidative stress might be an important factor contributing to injury during alloimmune activation. Herein, we evaluated the efficacy of a superoxide dismutase mimetic, manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride (MnTmPyP), on cytokine gene expression and apoptotic signaling in a rat model of cardiac transplantation.

METHODS

Lewis-->Lewis (isografts) or Wistar-Furth-->Lewis (allografts) heterotopic rat transplants without and with treatment with MnTmPyP were used. Reactive oxygen formation was determined on the basis of dihydroethidine fluorescence and lucigenin-enhanced chemiluminescence. In situ graft function was determined by means of sonomicrometry. Inflammatory cytokine, proapoptotic, and antiapoptotic gene expression at either postoperative day 4 (early rejection) or postoperative day 6 (late rejection) was determined by means of reverse transcriptase polymerase chain reaction.

RESULTS

An increased production of reactive oxygen in allografts was inhibited to isograft control levels by MnTmPyP. MnTmPyP restored either the percentage of fractional shortening, the distended diastolic and systolic myocardial segment lengths, or both in allografts. Of the increases in cytokine and proapoptotic gene expression in allografts, only interleukin 6 was decreased by MnTmPyP. MnTmPyP inhibited antiapoptotic gene expression (Bcl-2 and Bcl-xL) during early rejection but restored expression at later stages. The increase in activated caspase-3 levels in allografts was inhibited by MnTmPyP.

CONCLUSIONS

The mechanism of the beneficial effect of MnTmPyP on graft function appear related, in part, to scavenging O2*- and by decreasing apoptotic signaling rather than an effect on inflammatory cytokine gene expression.

Identifying and defusing weapons of mass inflammation in carcinogenesis

The continued cancer risks associated with chronic inflammation necessitate the identification of inflammatory molecules and the cancer pathways they affect. Evidence indicates that there are multiple mechanisms linking inflammation to cancer and that there are multiple targets for chemoprevention. Here, we review some of the key factors and the cancer pathways they disturb as a necessary prerequisite to the identification of targets for chemoprevention.

Shock, inflammation and PARP

The activation of poly(ADP-ribose) polymerase (PARP) is well considered to play an important role in various patho-physiological conditions like inflammation and shock. A vast amount of circumstantial evidence implicates oxygen-derived free radicals (especially, superoxide and hydroxyl radical) and high-energy oxidants (such as peroxynitrite) as mediators of inflammation and shock. ROS (e.g., superoxide, peroxynitrite, hydroxyl radical and hydrogen peroxide) are all potential reactants capable of initiating DNA single strand breakage, with subsequent activation of the nuclear enzyme poly(ADP-ribose) synthetase (PARS), leading to eventual severe energy depletion of the cells, and necrotic-type cell death. During the last years, numerous experimental studies have clearly demonstrated the beneficial effects of PARP inhibition in cell cultures through rodent models and more recently in pre-clinical large animal models of acute and chronic inflammation. The aim of this review is to describe recent experimental evidence implicating PARP as a pathophysiological modulator of acute and chronic inflammation.

Reduction of antigen-induced respiratory abnormalities and airway inflammation in sensitized guinea pigs by a superoxide dismutase mimetic

Reactive oxygen species have been implicated in the pathogenesis of asthma and, in atopic asthmatics, endogenous superoxide dismutase (SOD) enzyme levels are known to decrease. This suggests that replacing a failed endogenous SOD enzyme system with a mimetic of the endogenous enzyme would be beneficial and protective. In this study we demonstrate that removal of superoxide by the SOD mimetic (SODm) M40403 reduces the respiratory and histopathological lung abnormalities due to ovalbumin (OA) aerosol in a model of allergic asthma-like reaction in sensitized guinea pigs. Both respiratory abnormalities and bronchoconstriction in response to OA challenge are nearly absent in naïve animals, while they sharply became severe in sensitized animals. In addition, OA aerosol induced a reduction of MnSOD activity which was paralleled with bronchiolar lumen reduction, pulmonary air space hyperinflation, mast cell degranulation, eosinophil infiltration, bronchial epithelial cell apoptosis, increase in myeloperoxidase activity, malonyldialdehyde production and 8-hydroxy-2'-deoxyguanosine formation in the lung tissue, as well as elevation of PGD2 in the bronchoalveolar lavage fluid. Treatment with M40403 restored the levels of MnSOD activity and significantly reduced all the above parameters. In summary, our findings support the potential therapeutic use of SOD mimetics in asthma and anaphylactic reactions and account for a critical role for superoxide in acute allergic asthma-like reaction in actively sensitized guinea pig.

M40403 prevents myocardial injury induced by acute hyperglycaemia in perfused rat heart

M40403 is a low-molecular-weight, synthetic manganese-containing biscyclohexylpyridine superoxide dismutase mimetic (SODm) that removes superoxide anions (O(2)(-)) without interfering with other reactive species known to be involved in cardiovascular alterations (e.g. nitric oxide [NO] and peroxynitrite [ONOO(-)]). As such, M40403 represents an important pharmacological tool to dissect the roles of O(2)(-) in functional and biochemical cardiovascular alterations induced by perfusion of high glucose concentrations into the heart. Perfusion of a high glucose concentration of glucose into the heart elicited important cardiovascular alterations characterized by QT interval prolongation, increase in coronary perfusion pressure (CPP), lipid peroxidation, decrease in MnSOD activity and DNA damage. All parameters of cardiovascular alteration were attenuated by M40403 (1-10 mg/l). Furthermore, perfusion of a high of glucose concentration induced a significant formation of nitrotyrosine as well as an activation of poly(adenosine diphosphate [ADP]-ribose) synthetase (PARS), as determined by immunohistochemical analysis of heart tissue. The extent of staining for nitrotyrosine and PARS was reduced by M40403. These results clearly indicate that O(2)(-) plays a critical role in the development of the functional and biochemical cardiovascular alterations induced by perfusion of a high concentration of glucose into the heart. Therefore, synthetic enzymes of SOD, such as M40403, offer a novel therapeutic approach for the management of various cardiovascular diseases where these radicals have been postulated to play a role.

Activation of nuclear factor-kappa B and effects of pyrrolidine dithiocarbamate on TNBS-induced rat colitis

AIM: To explore the changes of nuclear factor-kappa B (NF-κB) DNA-binding activity, the expression of intercellular adhesion molecule-1 (ICAM-1) regulated by NF-κB at various times and to evaluate the effects of pyrrolidine dithiocarbamate (PDTC) on trinitrobenzene sulfonic acid (TNBS)-induced rat colitis.

METHODS: TNBS of 0.6 mL was mixed with ethanol of 0.3 mL solution and instilled into the lumen of the rat colon. The rat models were divided into 6 groups, which were killed at 24 h, 3, 7, 14, and 21 d after enema. Colonic inflammation and damage were assessed by macroscopical and histological criteria. Activity of NF-κB DNA-binding was analyzed by electrophoresis mobility shift assays (EMSA). Expression of ICAM-1 was detected by in situ hybridization (ISH) and immunohistochemistry (IH). Then various doses of PDTC were injected into rat abdomen 30 min before enema with TNBS/ethanol as pretreatment. The rats were killed 4 h after enema and the colonic inflammation, myeloperoxidase (MPO) activity, malondialdehyde (MDA) level, and DNA-binding activity of NF-κB were assessed. Finally, PDTC was injected intraperitoneally after colitis was induced. Changes of morphology were assayed.

RESULTS: During the first week, hyperemia, hemorrhage, edema and ulceration of the colonic mucosa appeared with predominant infiltration of leukocytes. Neutrophils, macrophages, lymphocytes infiltrated in mucosa and submucosa 14 d later. Fibroblasts and granuloma-like structures were also obviously seen. The binding activity of NF-κB began to increase at 24 h time point and reached a peak at 14 d, then decreased but still was higher than control group at 21 d (P<0.01). Levels of ICAM-1 mRNA and protein significantly elevated at 24 h and the peak was at 21 d. Pretreatment with PDTC could attenuate the development of inflammation but not by reducing NF-κB activity. This attenuation of inflammation had a positive relationship with the dose of PDTC. PDTC at the dose of 100 mg/kg had no therapeutic effect after colitis was induced.

CONCLUSION: NF-κB activation is an important event that may be involved in acute and chronic inflammation development and may contribute to self-protection against early inflammation damage. NF-κB also regulates ICAM-1 expression during colonic inflammation. Pretreatment of PDTC may attenuate the inflammation development. But PDTC has no therapeutic effect after the colitis is induced.

Hyperglycemia in streptozotocin-induced diabetic rat increases infarct size associated with low levels of myocardial HO-1 during ischemia/reperfusion

This study investigated the role of heme oxygenase (HO)-1 in the cardiac tissue injury of acute ischemia/reperfusion (I/R) in diabetic streptozotocin (STZ)-induced hyperglycemic rats. The effects of 1) hemin, an inducer of HO expression and activity, and 2) zinc protoporphyrin IX (ZnPP-IX), an inhibitor of HO activity, have also been investigated on the tissue injury by I/R and some mediators released in these circumstances. STZ hyperglycemic rats had impaired levels of HO-1 within the cardiac tissue and increased myocardial infarct size (IS) following I/R, as compared with the nondiabetic rats. In these rats, administration of hemin 4 mg/kg 18 h before I/R increases the levels of HO-1 within the tissue. However, the values of HO-1 assayed in these circumstances were significantly lower (P < 0.01) than those assayed in nondiabetic animals subjected to the same procedures; IS was much more extended (P < 0.01) than in the parent nondiabetic group. STZ hyperglycemic rats also predisposed the heart to produce high levels of the cytokines interleukin (IL)-1beta and CXCL8. Subsequent I/R further increased (P < 0.01) the cytokine production, an effect partly prevented by hemin treatment. This recovered the huge number of infiltrated polymorphonuclear (PMN) leukocytes within the cardiac tissue associated with the STZ hyperglycemic state and I/R damage.

Effect of the H, K-ATPase inhibitor, esomeprazole magnesium, on gut total antioxidant capacity in mice

Antioxidant depletion is believed to be a mechanism involved in the pathophysiology of several upper gastrointestinal disorders, and H, K-ATPase inhibitors can alter free radical production by neutrophils. We hypothesized that the H, K-ATPase inhibitor esomeprazole magnesium would decrease gut free radical production with a concomitant increase in gut total antioxidant capacity. A/J mice (n = 10/group) received either vehicle (control) or one of three concentrations of esomeprazole magnesium in vehicle by once-daily gavage for 10 days. Using tissue extracts from stomach and colon, total antioxidant capacity, lipid peroxide levels, and constitutive Cu/Zn-superoxide dismutase were measured using validated assays. There was a dose-related increase in total antioxidant capacity (analysis of variance, P < 0.001) in stomach, but there was no change in the colon. In the assessment of free radical production, there was a trend toward decreased lipid peroxide levels in stomach from mice receiving esomeprazole. In stomach, Cu/Zn-superoxide dismutase activity was increased (ANOVA: p=.03) in mice receiving esomeprazole. In conclusion, gastric total antioxidant capacity and Cu/Zn-superoxide dismutase activity are increased by esomeprazole, and these changes may result in part from decreased free radical production. The present results support the notion that the pharmacological effects of this agent on upper intestinal tissue are more complex than previously thought, and appear to involve both enzymatic and nonenzymatic tissue antioxidants.

Beneficial effects of GW274150 treatment on the development of experimental colitis induced by dinitrobenzene sulfonic acid

Inflammatory bowel disease is associated with inducible nitric oxide synthase (iNOS) expression, oxidative and nitrosative stress, and leukocyte infiltration in the colon. Here, we investigate the effects of the selective iNOS-inhibitor (S)-2-amino-(1-iminoethylamino)-5-thiopentanoic acid (GW274150) on the development of experimental colitis induced by dinitrobenzene sulfonic acid. When compared to dinitrobenzene sulfonic acid-treated mice, GW274150 (5 mg/kg i.p.)-treated mice subjected to dinitrobenzene sulfonic ACID-induced colitis experienced a significantly lower rate of the extent and severity of the histological signs of colon injury. Dinitrobenzene sulfonic acid-treated mice experienced hemorrhagic diarrhoea and weight loss. At 4 days after the administration of dinitrobenzene sulfonic acid, the mucosa of the colon exhibited large areas of necrosis. Immunohistochemistry for nitrotyrosine and poly (ADP-ribose) (PAR) showed an intense staining in the inflamed colon. Treatment of dinitrobenzene sulfonic acid-treated mice with GW274150 significantly reduced the degree of hemorrhagic diarrhoea and weight loss caused by administration of dinitrobenzene sulfonic acid. GW274150 also caused a substantial reduction of (i) the degree of colon injury, (ii) the rise in myeloperoxidase (MPO) activity (mucosa), (iii) the increase in staining (immunohistochemistry) for nitrotyrosine, as well as (iv) PARP activation caused by dinitrobenzene sulfonic acid in the colon. Thus, GW274150 treatment reduced the degree of colitis caused by dinitrobenzene sulfonic acid. We propose that selective inhibition of iNOS activity with GW274150 may be useful in the treatment of inflammatory bowel disease.

Catalytic antioxidants: a radical approach to new therapeutics

In humans, several pathologies involve the overproduction of reactive oxygen species. Metal-containing catalytic antioxidants have emerged as a novel class of potential therapeutic agents that scavenge a wide range of reactive oxygen species. There are three structural classes of manganese-containing catalytic antioxidants that have efficacy in several oxidative stress models of human disease. The classes are divided based on their in vitro selectivity towards the scavenging of superoxide. The selective catalytic antioxidants include the macrocyclics, whereas the non-selective catalytic antioxidants include the salens and porphyrins. Cardiovascular, neurodegenerative and inflammatory lung disorders are all potentially important targets for catalytic antioxidant therapy.

Role of endogenous and exogenous ligands for the peroxisome proliferators activated receptors alpha (PPAR-alpha) in the development of inflammatory bowel disease in mice

The peroxisome proliferator-activated receptor-alpha (PPAR-alpha) is a member of the nuclear receptor superfamily of ligand-dependent transcription factors related to retinoid, steroid and thyroid hormone receptors. The aim of the present study was to examine the effects of endogenous and exogenous PPAR-alpha ligand on the development of experimental colitis. To address this question, we used an experimental model of colitis, induced by dinitrobenzene sulfonic acid (DNBS). When compared to DNBS-treated PPAR-alpha wild-type (WT) mice, DNBS-treated PPAR-alpha knockout mice (PPAR-alphaKO) mice experienced a higher rate of the extent and severity of the histological signs of colon injury. After administration of DNBS PPAR-alphaWT mice experienced hemorrhagic diarrhea, weight loss and large areas of necrosis in the mucosa of the colon were also observed. Neutrophil infiltration was associated with upregulation of ICAM-1. Immunohistochemistry for nitrotyrosine showed an intense staining in the inflamed colon. Absence of a functional PPAR-alpha gene in PPAR-alphaKO mice resulted in a significant augmentation of all the above-described parameters. On the contrary, the treatment of PPAR-alphaWT with Wy-14643 (1 mg/kg daily i.p) significantly reduced: (i) the degree of hemorrhagic diarrhea and weight loss, (ii) the degree of colon injury, (iii) the rise in MPO activity (mucosa), (iv) the increase in staining (immunohistochemistry) for nitrotyrosine, as well as (v) the upregulation of ICAM-1 caused by DNBS in the colon. In order to elucidate whether the protective effects of Wy-14643 is related to activation of the PPAR-alpha receptor, we also investigated the effect the of Wy-14643 treatment on PPAR-alpha-deficient mice. The absence of the PPAR-alpha receptor significantly abolished the protective effect of the PPAR-alpha agonist against DNBS-induced colitis. Thus, endogenous and exogenous PPAR-alpha ligands reduce the degree of colitis caused by DNBS. We propose that PPAR-alpha ligand may be useful in the treatment of inflammatory bowel disease.

Severity of sepsis alters the effects of superoxide anion inhibition in a rat sepsis model

Previous analysis showed that selective inhibitors of five different host inflammatory mediators administered for sepsis, although beneficial with severe sepsis and high-control mortality rates, were ineffective or harmful with less severe sepsis. We hypothesized that severity of sepsis would also influence inhibition of superoxide anion, another inflammatory mediator. To test this, 6-h infusions of M40401, a selective SOD mimetic, or placebo were given to antibiotic-treated rats ( n = 547) starting 3 h after challenge with differing doses of intravenous Escherichia coli designed to produce low- or high-control mortality rates. There was a positive and significant ( P = 0.0008) relationship between the efficacy of M40401 on survival rate and control mortality rates. M40401 increased or decreased the log (odds ratio of survival) (means ± SE), dependent on whether control mortality rates were greater or less than the median (66%) (+0.19 ± 0.12 vs. −0.25 ± 0.10, P = 0.01). In a subset of animals examined ( n = 152) at 9 h after E. coli challenge, M40401 increased (mean effect ± SE compared with control) mean arterial blood pressure (8 ± 5 mmHg) and decreased platelets (−37 ± 22 cells × 103/ml) with high-control mortality rates but had opposing effects on each parameter (−3 ± 3 mmHg and 28 ± 19 cells × 103/ml, respectively) with low rates ( P ≤ 0.05 for the differing effects of M40401 on each parameter with high- vs. low-control mortality rates). A metaregression analysis of published preclinical sepsis studies testing SOD preparations and SOD mimetics showed that most (16 of 18) had control mortality rates >66%. However, across experiments from published studies, these agents were less beneficial as control mortality rate decreased ( P = 0.03) in a relationship not altered ( P = not significant) by other variables associated with septic challenge or regimen of treatment and which was similar, compared with experiments with M40401 ( P = not significant). Thus, in these preclinical sepsis models, possibly related to divergent effects on vascular function, inhibition of superoxide anion improved survival with more severe sepsis and high-control mortality rates but was less effective or harmful with less severe sepsis. Extrapolated clinically, inhibition of superoxide anion may be most efficacious in septic patients with severe sepsis and a high risk of death.

Erythropoietin reduces the development of experimental inflammatory bowel disease

Inflammatory bowel disease is characterized by oxidative and nitrosative stress, leukocyte infiltration, and up-regulation of the expression of intercellular adhesion molecule-1 (ICAM-1) in the colon. Erythropoietin (EPO) is a potent stimulator of erythroid progenitor cells, and its expression is enhanced by hypoxia. Here we investigate the effects EPO has on the development of experimental colitis. To address this question, we used an experimental model of colitis induced by dinitrobenzene sulfonic acid (DNBS). When compared with DNBS-treated mice, EPO (1000 IU/kg day s.c.)-treated mice subjected to DNBS-induced colitis experienced significantly lower rates in the extent and severity of the histological signs of colon injury. DNBS-treated mice experienced diarrhea and weight loss. At 4 days after administration of DNBS, the mucosa of the colon exhibited large areas of necrosis. Neutrophil infiltration (determined by histology as well as an increase in myeloperoxidase activity in the mucosa) was associated with up-regulation of ICAM-1. Immunohistochemistry for nitrotyrosine and poly(ADP-ribose) showed an intense staining in the inflamed colon. On the contrary, the treatment of DNBS-treated mice with EPO significantly reduced the degree of diarrhea and weight loss caused by administration of DNBS. EPO also caused a substantial reduction of the degree of colon injury, the rise in myeloperoxidase activity (mucosa), and the increase in staining (immunohistochemistry) for nitrotyrosine as well as the up-regulation of ICAM-1 caused by DNBS in the colon. Thus, treatment of rat with EPO reduces the degree of colitis caused by DNBS. We propose that EPO may be useful in the treatment of inflammatory bowel disease.

Superoxide dismutase ameliorates TNBS-induced colitis by reducing oxidative stress, adhesion molecule expression, and leukocyte recruitment into the inflamed intestine

Oxidant stress has been implicated in the pathogenesis of inflammatory bowel disease. Antioxidant enzymes, such as superoxide dismutase (SOD), are candidate drugs for modulating this pathogenic factor. This study was designed to determine the therapeutic value of SOD in an experimental model of colitis and to study the mechanisms underlying its effects on intestinal inflammation. For that purpose, colitic (trinitrobenzene sulfonic acid-induced) and control rats were studied. Groups of colitic animals were treated with different doses of SOD (1, 4, or 13 mg/kg/day) or vehicle, starting after induction of colitis and during 7 days. Clinical and pathological markers of colitis severity and lipid peroxidation in colonic tissue were measured. Leukocyte-endothelial cell interactions in colonic venules and expression of vascular cell adhesion molecule 1 (VCAM-1) were determined. Development of colitis was associated with a significant loss in body weight, an increase in macroscopic and microscopic damage scores, and colonic myeloperoxidase activity. Administration of SOD significantly attenuated these changes in a dose-dependent manner and reduced lipid peroxidation in colonic tissue. The increase in leukocyte rolling and adhesion in colonic venules of colitic rats were significantly reduced by administration of SOD, 13 mg/kg/day. Development of colitis was associated with a marked increase in endothelial VCAM-1 expression, which was significantly reduced by treatment with SOD. In conclusion, treatment with SOD significantly reduces peroxidation reactions in the inflamed colon and affords significant amelioration of colonic inflammatory changes in experimental colitis. This effect is related to a reduction in VCAM-1 expression and leukocyte recruitment into the inflamed intestine.

On the selectivity of superoxide dismutase mimetics and its importance in pharmacological studies

The list of pathophysiological conditions associated with the overproduction of superoxide expands every day. Much of the knowledge compiled on the role of this radical in disease has been gathered using the native superoxide dismutase enzyme and, more recently, by the use of superoxide dismutase knockout models or transgenic models that overexpress the various isoforms of the enzyme. Although the native enzyme has shown promising anti-inflammatory properties in both preclinical and clinical studies, there were drawbacks and issues associated with its use as a therapeutic agent and pharmacological tool. Based on the concept that removal of superoxide modulates the course of inflammation, synthetic, low-molecular-weight mimetics of the superoxide dismutase enzymes that could overcome some of the limitations associated with the use of the native enzyme have been designed. In this review, we will discuss the advances made using various superoxide dismutase mimetics that led to the proposal that superoxide (and/or the product of its interaction with nitric oxide, peroxynitrite) is an important mediator of inflammation, and to the conclusion that superoxide dismutase mimetics can be utilized as therapeutic agents in diseases of various etiologies. The importance of the selectivity of such compounds in pharmacological studies will be discussed.

Ameliorating effects of the immunomodulator 3-(2-ethylphenyl)-5-(3-methoxyphenyl)-1H-1,2,4-triazole in an experimental model of colitis in the rat

The therapeutic efficacy of the immunomodulator 3-(2-ethylphenyl)-5-(3-methoxyphenyl)-1H-1,2,4-triazole (ST1959) in colonic inflammation was assessed in rats. One hour following colonic instillation of ethanolic 2,4,6-trinitrobenzene sulphonic acid (TNBS), intracolonic administration of 0.4 mg/kg ST1959 was started and continued once daily for 1 or 2 weeks. Daily administration of ST1959 for 1 week significantly reduced macroscopic and histological damage, myeloperoxidase activity, and colonic tissue levels of tumour necrosis factor-alpha and interferon-gamma. ST1959 did not affect interleukin-12 levels but significantly enhanced the production of interleukin-10 (sixfold increase). Two weeks of ST1959 treatment reduced the thickness of the colonic wall and myeloperoxidase activity to the same extent, and the histologic appearance of the mucosa was largely restored. The ameliorating effects seem to be ascribable to an impairment of both neutrophil infiltration/activation and tumour necrosis factor-alpha and interferon-gamma production, possibly consequent to the observed increase in the colonic tissue levels of the potent anti-inflammatory cytokine interleukin-10. Similar results were observed with the reference drug 5-aminosalycilic acid.

HIGH-DENSITY LIPOPROTEINS REDUCE THE INTESTINAL DAMAGE ASSOCIATED WITH ISCHEMIA/REPERFUSION AND COLITIS

High-density lipoproteins (HDLs) have been shown to reduce the organ injury and mortality in animal models of shock by reducing the expression of adhesion molecules and proinflammatory enzymes. However, there is limited evidence that HDL treatment reduces inflammation. As inflammation plays an important role in the development of colitis as well as ischemia/reperfusion (I/R) injury of the intestine, we have investigated the effects of HDL in animal models of associated with gut injury and inflammation (splanchnic artery occlusion [SAO] shock and dinitrobenzene sulfonic acid [DNBS]-induced colitis). We report here for the first time that the administration of reconstituted HDLs (recHDLs; 80 mg/kg i.v. bolus 30 min prior to ischemia in the SAO-shock model or 40 mg/kg i.v. every 24 h in the colitis model) exerts potent anti-inflammatory effects (e.g., reduced inflammatory cell infiltration and histological injury, and delayed the development of the clinical signs) in vivo. Furthermore, recHDL reduced the staining for nitrotyrosine and poly(ADP-ribose) (immunohistochemistry) and the expression of intercellular adhesion molecule-1 in the ileum of SAO-shocked rats and in the colon from DNBS-treated rats. Thus, recHDL reduces the inflammation caused by intestinal I/R and colitis. HDLs may represent a novel therapeutic approach for the therapy of inflammation of the gut.

Decreased oxidative stress in patients with ulcerative colitis supplemented with fish oil omega-3 fatty acids

OBJECTIVE

The potential pathogenicity of free radicals may have a pivotal role in ulcerative colitis. Fish oil omega-3 fatty acids exert anti-inflammatory effects on patients with ulcerative colitis (UC), but the precise mechanism of the action of fish oil on oxidative stress is still controversial. The aim of the present work was to verify the blood oxidative stress in patients with UC and determine whether the association of sulfasalazine to fish oil omega-3 fatty acids is more effective than isolated use of sulfasalazine to reduce the oxidative stress.

METHODS

Nine patients (seven female and two male; mean age = 40 +/- 11 y) with mild or moderate active UC were studied in a randomized crossover design. In addition to their usual medication (2 g/d of sulfasalazine), they received fish oil omega-3 fatty acids (4.5 g/d) or placebo for 2-mo treatment periods that were separated by 2 mo, when they only received sulfasalazine. Nine healthy individuals served as control subjects to study the oxidative stress status. Disease activity was assessed by laboratory indicators (C-reactive protein, alpha1-acid glycoprotein, alpha1-antitrypsin, erythrocyte sedimentation rate, albumin, hemoglobin, and platelet count), sigmoidoscopy, and histology scores. Analysis of oxidative stress was assessed by plasma chemiluminescence and erythrocyte lipid peroxidation, both induced by tert butyl hydroperoxide (t-BuOOH) and by plasma malondialdehyde. Antioxidant status was assayed by total plasma antioxidant capacity (TRAP) and microsomal lipid peroxidation inhibition (LPI). Superoxide dismutase (SOD) and catalase erythrocyte enzymatic activities were also determined.

RESULTS

No significant changes were observed in any laboratory indicator or in the sigmoidoscopy or histology scores, with the exception of erythrocyte sedimentation rate, which decreased with both treatments. Oxidative stress was demonstrated by significant decreases in TRAP and LPI levels, increased chemiluminescence induced by t-BuOOH, and higher SOD activity in patients with UC. Treatment with fish oil omega-3 fatty acids reverted the chemiluminescence induced by t-BuOOH and LPI to baseline levels but that did not occur when patients received only sulfasalazine. Levels of plasma malondialdehyde, erythrocyte lipid peroxidation, and catalase were not different from those in the control group.

CONCLUSIONS

The results indicated that plasma oxidative stress occurs in patients with UC, and there was a significant decrease when the patients used sulfasalazine plus fish oil omega-3 fatty acids. However, there was no improvement in most laboratory indicators, sigmoidoscopy, and histology scores. The results suggested that omega-3 fatty acids may act as free radical scavengers protecting the patients against the overall effect of oxidative stress.

Superoxide dismutases in the lung and human lung diseases

The lungs are directly exposed to higher oxygen concentrations than most other tissues. Increased oxidative stress is a significant part of the pathogenesis of obstructive lung diseases such as asthma and chronic obstructive pulmonary disease, parenchymal lung diseases (e.g., idiopathic pulmonary fibrosis and lung granulomatous diseases), and lung malignancies. Lung tissue is protected against these oxidants by a variety of antioxidant mechanisms among which the superoxide dismutases (SODs) are the only ones converting superoxide radicals to hydrogen peroxide. There are three SODs: cytosolic copper-zinc, mitochondrial manganese, and extracellular SODs. These enzymes have specific distributions and functions. Their importance in protecting lung tissue has been confirmed in transgenic and knockout animal studies. Relatively few studies have been conducted on these enzymes in the normal human lung or in human lung diseases. Most human studies suggest that there is induction of manganese SOD and, possibly, extracellular SOD during inflammatory, but not fibrotic, phases of parenchymal lung diseases and that both copper-zinc SOD and manganese SOD may be downregulated in asthmatic airways. Many previous antioxidant therapies have been disappointing, but newly characterized SOD mimetics are being shown to protect against oxidant-related lung disorders in animal models.

Effect of oxidants on small intestinal brush border membranes and colonic apical membranes--a comparative study

This study compares composition of the rat small intestinal brush border membranes (BBM) and colonic apical membranes (CAM) and their susceptibility to in vitro exposure to various oxidants. Differences were observed between BBM and CAM in their lipid composition, sugar content, alkaline phosphatase (ALP) activity and cholesterol/phospholipid ratio. BBM and CAM were exposed to superoxide generated by xanthine+xanthine oxidase (X-XO) or peroxides such as tertiary butyl hydroperoxide (tBuOOH) and hydrogen peroxide (H(2)O(2)) and alterations in ALP activity, peroxidation parameters and membrane lipids were analyzed. Exposure of BBM and CAM to superoxide resulted in decrease in ALP activity and increase in peroxidation parameters such as protein carbonyl content, malondialdehyde and conjugated diene. Superoxide exposure also resulted in lipid alterations specifically in certain phospholipids. These alterations were prevented either by superoxide dismutase or by allopurinol. Peroxides did not have any significant effect. These results suggest that both BBM and CAM are susceptible to superoxide, which can bring about peroxidation and degradation of membrane lipids specifically, certain phospholipids.