Experimental colitis is ameliorated by inhibition of nitric oxide synthase activity

The effect of montelukast, a leukotriene receptor antagonist, on the acetic acid-induced model of colitis in rats: Involvement of NO-cGMP-KATP channels pathway

Inflammatory bowel disease is a chronic autoimmune disorder that may involve entire gastrointestinal tract. The leukotrienes have a role as mediators in the pathophysiology of colitis. Here, we investigated the effect of a leukotriene receptor antagonist, montelukast, and also the role of the NO-cGMP-K_ATP channel pathway in acetic acid-induced colitis. Rectal administration of acetic acid (4%) was used for induction of colitis in rats. To investigate our hypothesis, the rats were intraperitoneally pre-treated with L-NAME (NOS inhibitor), L-arginine, sildenafil, methylene blue, glibenclamide, or diazoxide 15 min before treatment with montelukast (5-20 mg/kg, i. p.), for three consecutive days. Then, microscopic, macroscopic, and inflammatory parameters were evaluated. Montelukast reduced the microscopic and macroscopic damage induced by acetic acid. Montelukast also reduced the level of IL-1β and TNF-α. We also showed that the effects of montelukast were significantly attenuated by L-NAME, methylene blue (guanylate cyclase inhibitor), and an ATP-sensitive potassium channel blocker (glibenclamide). Also, the administration of L-arginine, sildenafil, and diazoxide before montelukast produced protective effect. In conclusion, the pathway of the NO-cGMP-KATP channel is involved in the protective effect of montelukast in acetic acid-induced colonic tissue damage.

Favourable effects of whey protein on acetic acid-induced ulcerative colitis in a rat model

INTRODUCTION

In the present study, we aimed to examine the effects of the administration of whey protein through rectal enema to rats with acetic acid-induced ulcerative colitis on the pathways of nuclear-related factor-2 (Nrf-2), haem oxygenase-1 (HO-1), nuclear factor κB (NF-κB), active protein kinase-1 (AP-1), tumour necrotising factor-α (TNF-α), and cyclooxygenase-2 (COX-2), IL-6, IL-10.

MATERIAL AND METHODS

Twenty-eight rats were employed for the trial. Ulcerative colitis was induced through the use of acetic acid. The therapeutic doses of whey protein were administered rectally. Ulcerative colitis was subjected to histopathological examination and protein levels in colon tissue were measured with the Western blot method.

RESULTS

The significant increases observed in the levels of AP-1, COX-2, IL-6, IL-10, NF-κB, and TNF-α as markers of inflammation following the development of ulcerative colitis showed remarkable decreases along with the administration of whey protein (p < 0.05). On the other hand, we identified a decrease in the Nrf2-ARE signal pathway and HO-1 protein having protective roles in the colon inflammatory response along with the development of ulcerative colitis and activation of the Nrf2-HO-1 pathway by the whey protein.

CONCLUSIONS

Whey protein modulates Nrf2/HO-1 and NF-kB pathways, thereby creating a therapeutic effect against colonic inflammation induced by acetic acid (AA) due to its anti-inflammatory effects.

Hybrids as NO Donors

Cinnamic acid and its derivatives have been studied for a variety of biological properties, including anti-inflammatory, antioxidant, anticancer, antihypertensive, and antibacterial. Many hybrids of cinnamic derivatives with other bioactive molecules have been synthesized and evaluated as nitric oxide (NO) donors. Since NO plays a significant role in various biological processes, including vasodilation, inflammation, and neurotransmission, NO donor groups are incorporated into the structures of already-known bioactive molecules to enhance their biological properties. In this review, we present cinnamic hybrids with NO-donating ability useful in the treatment of several diseases.

PEA/Polydatin: Anti-Inflammatory and Antioxidant Approach to Counteract DNBS-Induced Colitis

Palmitoylethanolamide (PEA) has well-known anti-inflammatory effects. However, PEA does not possess an antioxidant ability. A comicronized formulation of ultramicronized PEA (um-PEA) and polydatin (Pol) PEA/Pol, a biological precursor of resveratrol with antioxidant activity, could have protective effects on oxidative stress produced by inflammatory processes. We evaluated the effects of a comicronized PEA/Pol 10 mg/kg (9 mg of um-PEA+1 mg of polydatin) in a model of Dinitrobenzene sulfonic acid (DNBS)-induced colitis. Ulcerative colitis was induced in mice by intrarectally injection of DNBS (4 mg in 100 µL of 50% ethanol per mouse). Macroscopic and histologic colon alterations and marked clinical signs were observed four days after DNBS and elevated cytokine production. The myeloperoxidase (MPO) activity assessed for neutrophil infiltration was associated with ICAM-1 and P-selectin adhesion controls in colons. Oxidative stress was detected with increased poly ADP-ribose polymerase (PARP) and nitrotyrosine positive staining and malondialdehyde (MDA) levels in inflamed colons. Macroscopic and histologic alterations minimized by oral PEA/Pol, as well as neutrophil infiltration, inflammatory cytokine release, MDA, nitrotyrosine, PARP and ICAM-1, and P-selectin expressions. The mechanism of action of PEA/Pol could be related to the sirtuin 1/nuclear factor erythroid 2-related factor 2 (SIRT-1/Nrf2) pathway and nuclear factor (NF)-κB. PEA/Pol administration inhibited NF-κB and increased SIRT-1/Nrf2 expressions. Our results show that PEA/Pol is capable of decreasing inflammatory bowel disease (IBD) DNBS-induced in mice.

Helicobacter hepaticus Induce Colitis in Male IL-10-/- Mice Dependent by Cytolethal Distending Toxin B and via the Activation of Jak/Stat Signaling Pathway

It has been well documented that cytolethal distending toxin (CDT) from Helicobacter hepaticus (H. hepaticus), Campylobacter jejuni (C. jejuni) and other Gram-negative intestinal pathogens is linked to the inflammatory bowel disease (IBD). However, the mechanisms underlying the progression of H. hepaticus induced colitis remains unclear. In this study, male B6.129P2-IL10^tm1Cgn/J mice were infected by H. hepaticus and ΔCdtB H. hepaticus for 6, 12, 18, and 24 weeks. Histopathology, H. hepaticus colonization levels, expression of inflammatory cytokines, signaling pathways, and content of NO in proximal colon were examined. We found that Cytolethal distending toxin subunit B (CdtB) deletion had no influence on colonization ability of H. hepaticus in colon of B6.129P2-IL10^tm1cgn/J mice, and there was no significant difference in abundance of colonic H. hepaticus over infection duration. H. hepaticus aggravated rectocele and proximal colonic inflammation, especially at 24 WPI, while ΔCdtB H. hepaticus could not cause significant symptom. Furthermore, mRNA levels of Il-6, Tnf-α, Il-1β, and iNOS significantly increased in the proximal colon of H. hepaticus-infected mice compared to ΔCdtB H. hepaticus infected group from 12 WPI to 24 WPI. In addition, the elevated content of NO and activated Stat3 and Jak2 in colon were observed in H. hepaticus infected mice. These data demonstrated that CdtB promote colitis development in male B6.129P2-IL10^tm1Cgn/J mice by induction of inflammatory response and activation of Jak-Stat signaling pathway.

Amino Acids in Intestinal Physiology and Health

Dietary protein digestion is an efficient process resulting in the absorption of amino acids by epithelial cells, mainly in the jejunum. Some amino acids are extensively metabolized in enterocytes supporting their high energy demand and/or production of bioactive metabolites such as glutathione or nitric oxide. In contrast, other amino acids are mainly used as building blocks for the intense protein synthesis associated with the rapid epithelium renewal and mucin production. Several amino acids have been shown to support the intestinal barrier function and the intestinal endocrine function. In addition, amino acids are metabolized by the gut microbiota that use them for their own protein synthesis and in catabolic pathways releasing in the intestinal lumen numerous metabolites such as ammonia, hydrogen sulfide, branched-chain amino acids, polyamines, phenolic and indolic compounds. Some of them (e.g. hydrogen sulfide) disrupts epithelial energy metabolism and may participate in mucosal inflammation when present in excess, while others (e.g. indole derivatives) prevent gut barrier dysfunction or regulate enteroendocrine functions. Lastly, some recent data suggest that dietary amino acids might regulate the composition of the gut microbiota, but the relevance for the intestinal health remains to be determined. In summary, amino acid utilization by epithelial cells or by intestinal bacteria appears to play a pivotal regulator role for intestinal homeostasis. Thus, adequate dietary supply of amino acids represents a key determinant of gut health and functions.

The Antioxidant and Anti-Inflammatory Properties of Anacardium occidentale L. Cashew Nuts in a Mouse Model of Colitis

Background: Anacardium occidentale L. is a tropical plant used for the treatment of inflammatory diseases. The goal of the present work was to investigate the anti-inflammatory and anti-oxidant potential of oral administration of cashew nuts (from Anacardium occidentale L.) in a mouse model of colitis. Methods: Induction of colitis was performed by intrarectally injection of dinitrobenzene sulfonic acid (DNBS). Cashew nuts were administered daily orally (100 mg/kg) in DNBS-injected mice. Results: Four days after DNBS, histological and macroscopic colon alterations as well as marked clinical signs and increased cytokine production were observed. Neutrophil infiltration, measured by myeloperoxidase (MPO) positive immunostaining, was correlated with up-regulation of adhesion molecules ICAM-1 and P-selectin in colons. Oxidative stress was detected with increased malondialdehyde (MDA) levels, nitrotyrosine, and poly ADP-ribose polymerase (PARP) positive staining in inflamed colons. Oral treatment with cashew nuts reduced histological, macroscopic damage, neutrophil infiltration, pro-inflammatory cytokines and MDA levels, as well as nitrotyrosine, PARP and ICAM-1, and P-selectin expressions. Colon inflammation could be related to nuclear factor (NF)-kB pathway activation and reduced manganese superoxide dismutase (MnSOD) antioxidant activity. Cashew nuts administration inhibited NF-kB and increased MnSOD antioxidant expressions. Conclusions: The results suggested that oral assumption of cashew nuts may be beneficial for the management of colitis.

The phosphatidic acid phosphatase lipin-1 facilitates inflammation-driven colon carcinogenesis

Colon cancer is a devastating illness that is associated with gut inflammation. Here, we explored the possible role of lipin-1, a phosphatidic acid phosphatase, in the development of colitis-associated tumorigenesis. Azoxymethane and dextran sodium sulfate-treated (DSS-treated) animals deficient in lipin-1 harbored fewer tumors and carcinomas than WT animals due to decreased cellular proliferation, lower expression of antiapoptotic and protumorigenic factors, and a reduced infiltration of macrophages in colon tumors. They also displayed increased resistance to DSS-induced colitis by producing less proinflammatory cytokines and experiencing less immune infiltration. Lipin-1-deficient macrophages from the colon were less activated and displayed lower phosphatidic acid phosphatase activity than WT macrophages isolated from DSS-treated animals. Transference of WT macrophages into lipin-1-deficient animals was sufficient to increase colitis burden. Furthermore, treatment of lipin-1-deficient mice with IL-23 exacerbated colon inflammation. Analysis of human databases from colon cancer and ulcerative colitis patients showed that lipin-1 expression is increased in those disorders and correlates with the expression of the proinflammatory markers CXCL1 and CXCL2. And finally, clinically, LPIN1 expression had prognostic value in inflammatory and stem-cell subtypes of colon cancers. Collectively, these data demonstrate that lipin-1 is a critical regulator of intestinal inflammation and inflammation-driven colon cancer development.

Cellular and Molecular Mediators of Intestinal Fibrosis

Intestinal fibrosis is a major complication of the inflammatory bowel diseases (IBD) and although inflammation is necessary for its development, it would appear that it plays a minor role in its progression as anti-inflammatory treatments in IBD do not prevent fibrosis once it has started. The processes that regulate fibrosis would thus appear to be distinct from those regulating inflammation and, therefore, a detailed understanding of these pathways is vital to the development of anti-fibrogenic strategies. There have been several recent reviews exploring what is known, and what remains unknown, about the development of intestinal fibrosis. This review is designed to add to this literature but with a focus on the cellular components that are involved in the development of fibrogenesis and the major molecular mediators that impact on these cells. The aim is to heighten the understanding of the factors involved in intestinal fibrogenesis so that detailed research can be encouraged in order to advance the processes that could lead to effective treatments.

Cellular and Molecular Mediators of Intestinal Fibrosis

Intestinal fibrosis is a major complication of the inflammatory bowel diseases (IBD) and although inflammation is necessary for its development, it would appear that it plays a minor role in its progression as anti-inflammatory treatments in IBD do not prevent fibrosis once it has started. The processes that regulate fibrosis would thus appear to be distinct from those regulating inflammation and, therefore, a detailed understanding of these pathways is vital to the development of anti-fibrogenic strategies. There have been several recent reviews exploring what is known, and what remains unknown, about the development of intestinal fibrosis. This review is designed to add to this literature but with a focus on the cellular components that are involved in the development of fibrogenesis and the major molecular mediators that impact on these cells. The aim is to heighten the understanding of the factors involved in intestinal fibrogenesis so that detailed research can be encouraged in order to advance the processes that could lead to effective treatments.

Dietary Polyphenols in the Aetiology of Crohn's Disease and Ulcerative Colitis-A Multicenter European Prospective Cohort Study (EPIC)

BACKGROUND

Oxidative stress may be involved in the aetiology of inflammatory bowel disease and whether dietary polyphenols, which possess antioxidants properties, prevent its development is unknown.

METHODS

A total of 401,326 men and women aged 20 to 80 years from 8 countries were recruited between 1991 and 1998 and at baseline completed validated food frequency questionnaires. Dietary polyphenol intake was measured using Phenol-Explorer, a database with information on the content of 502 polyphenols. Incident cases of Crohn's diseases (CD) and ulcerative colitis (UC) were identified during the follow-up period of up to December 2010. A nested case-control study using conditional logistic regression estimated the odds ratios (ORs), and 95% confidence intervals, for polyphenol intake (categories based on quartiles) and developing CD or UC.

RESULTS

In total, 110 CD (73% women) and 244 UC (57% women) cases were identified and matched to 440 and 976 controls, respectively. Total polyphenol intake was not associated with CD (P trend = 0.17) or UC (P trend = 0.16). For flavones and CD, there were reduced odds for all quartiles, which were statistically significant for the third (OR3rd versus 1st quartile = 0.33; 95% confidence interval, 0.15-0.69) and there was an inverse trend across quartiles (P = 0.03). Similarly, for resveratrol, there was an inverse association with CD (OR4th versus 1st quartile = 0.40; 95% confidence interval, 0.20-0.82) with an inverse trend across quartiles (P = 0.02). No significant associations between subtypes of polyphenols and UC were found. Effect modification by smoking in CD was documented with borderline statistical significance.

CONCLUSIONS

The data supports a potential role of flavones and resveratrol in the risk of developing CD; future aetiological studies should investigate these dietary components and further examine the potential for residual confounding.

Effect of roxithromycin on mucosal damage, oxidative stress and pro-inflammatory markers in experimental model of colitis

OBJECTIVE AND DESIGN

Roxithromycin, a macrolide antibiotic, exhibits anti-inflammatory property. The present study was designed to evaluate its protective effect in a rat model of colitis.

METHODS

The anti-inflammatory property of roxithromycin was first validated in rat paw edema model at 5 and 20 mg/kg doses where it produced 19 and 51% inhibition of paw swelling induced by carrageenan. The efficacy of roxithromycin was evaluated at these doses in a rat model where colitis was induced by intra-colonic instillation of acetic acid. Rats were divided into six groups viz. normal control, experimental control and drug-treated groups: roxithromycin 5 and 20 mg/kg, diclofenac 10 mg/kg and mesalazine 300 mg/kg. All drugs were given orally 1 h before induction of colitis. The macro and microscopic changes, mean ulcer score, mucus content and markers of oxidative stress and inflammation were evaluated in all the groups after 24 h.

RESULTS

Pretreatment with roxithromycin markedly decreased hyperemia, ulceration, edema and restored histological architecture. The protection afforded by roxithromycin was substantiated by dose-dependent increase in mucus content, normalization of markers of oxidative stress (GSH and TBARS) and levels of TNF-α, PGE₂ and nitrite along with marked decrease in expression of NFκB (p65), IL-1β and COX-2. The protective effect of roxithromycin was found to be comparable to mesalazine while diclofenac was found ineffective.

CONCLUSION

Our study demonstrates that roxithromycin ameliorates experimental colitis by maintaining redox homeostasis, preserving mucosal integrity and downregulating NFκB-mediated pro-inflammatory signaling and suggests that it has a therapeutic potential in inflammatory conditions of the colon.

Intestinal anti-inflammatory effects of goat whey on DNBS-induced colitis in mice

This study evaluated the intestinal anti-inflammatory effects of goat whey in a mouse model of colitis induced by 2,4-dinitrobenzenesulfonic acid that resembles human IBD. At a concentration of 4 g/kg/day, the goat whey improved the symptoms of intestinal inflammation, namely by decreasing the disease activity index, colonic weight/length, and leukocyte infiltration. Moreover, goat whey inhibited NF-κB p65 and p38 MAPK signaling pathways and consequently down-regulated the gene expression of various proinflammatory markers such as IL-1β, IL-6, IL-17, TNF-α, iNOS, MMP-9, ICAM-1. Also, goat whey increased the expression of proteins such as mucins, occludin proteins and cytokine signalling suppressors. The immunomodulatory properties of goat whey were also evaluated in vitro using the murine macrophage cell line Raw 264 and CMT-93 cells derived from mouse rectum carcinomas. The results revealed the ability of goat whey to inhibit the production of NO and reduce IL-6 production in LPS-stimulated cells. In conclusion, goat whey exhibited anti-inflammatory effects in the DNBS model of intestinal inflammation, and these observations were confirmed by its immunomodulatory properties in vitro. Together, our results indicate that goat whey could have applications for the treatment of IBD.

Gastrointestinal Inflammation: A Central Component of Mucosal Defense and Repair

The mucosal layer of the gastrointestinal (GI) tract is able to resist digestion by the endogenous substances that we secrete to digest foodstuffs. So-called “mucosal defense” is multifactorial and can be modulated by a wide range of substances, many of which are classically regarded as inflammatory mediators. Damage to the GI mucosa, and its subsequent repair, are also modulated by various inflammatory mediators. In this article, we provide a review of some of the key Inflammatory mediators that modulate GI mucosal defense, Injury, and repair. Among the mediators discussed are nitric oxide, polyamines, the elcosanolds (prostaglandins and II-poxlns), protease-activated receptors, and cytokines. Many of these endogenous factors, or the enzymes involved in their synthesis, are considered potential therapeutic targets for the treatment of diseases of the digestive tract that are characterized by Inflammation and ulceration.

Siblings of patients with Crohn's disease exhibit a biologically relevant dysbiosis in mucosal microbial metacommunities

OBJECTIVE

To determine the existence of mucosal dysbiosis in siblings of patients with Crohn's disease (CD) using 454 pyrosequencing and to comprehensively characterise and determine the influence of genotypical and phenotypical factors, on that dysbiosis. Siblings of patients with CD have elevated risk of developing CD and display aspects of disease phenotype, including faecal dysbiosis. Whether the mucosal microbiota is disrupted in these at-risk individuals is unknown.

DESIGN

Rectal biopsy DNA was extracted from 21 patients with quiescent CD, 17 of their healthy siblings and 19 unrelated healthy controls. Mucosal microbiota was analysed by 16S rRNA gene pyrosequencing and were classified into core and rare species. Genotypical risk was determined using Illumina Immuno BeadChip, faecal calprotectin by ELISA and blood T-cell phenotype by flow cytometry.

RESULTS

Core microbiota of both patients with CD and healthy siblings was significantly less diverse than controls. Metacommunity profiling (Bray-Curtis (SBC) index) showed the sibling core microbial composition to be more similar to CD (SBC=0.70) than to healthy controls, whereas the sibling rare microbiota was more similar to healthy controls (SBC=0.42). Faecalibacterium prausnitzii contributed most to core metacommunity dissimilarity both between siblings and controls, and between patients and controls. Phenotype/genotype markers of CD risk significantly influenced microbiota variation between and within groups, of which genotype had the largest effect.

CONCLUSIONS

Individuals with elevated CD-risk display mucosal dysbiosis characterised by reduced diversity of core microbiota and lower abundance of F. prausnitzii. This dysbiosis in healthy people at risk of CD implicates microbiological processes in CD pathogenesis.

MAG-EPA reduces severity of DSS-induced colitis in rats

Ulcerative colitis (UC) is a chronic disease characterized by diffuse inflammation of the intestinal mucosa of the large bowel. Omega-3 (ω3) fatty acid supplementation has been associated with a decreased production of inflammatory cytokines involved in UC pathogenesis. The aim of this study was to determine the preventive and therapeutic potential of eicosapentaenoic acid monoglyceride (MAG-EPA) in an in vivo rats model of UC induced by dextran sulfate sodium (DSS). DSS rats were untreated or treated per os with MAG-EPA. Morphological, histological, and biochemical analyses were performed following MAG-EPA administrations. Morphological and histological analyses revealed that MAG-EPA pretreatment (12 days pre-DSS) and treatment (6 days post-DSS) exhibited strong activity in reducing severity of disease in DSS rats. Following MAG-EPA administrations, tissue levels of the proinflammatory cytokines TNF-α, IL-1β, and IL-6 were markedly lower compared with rats treated only with DSS. MAG-EPA per os administration decrease neutrophil infiltration in colon tissues, as depicted by myelohyperoxidase activity. Results also revealed a reduced activation of NF-κB pathways correlated with a decreased expression of COX-2 in colon homogenates derived from MAG-EPA-pretreated and treated rats. Tension measurements performed on colon tissues revealed that contractile responses to methacholine and relaxing effect induced by sodium nitroprusside were largely increased following MAG-EPA treatment. The combined treatment of MAG-EPA and vitamin E displayed an antagonistic effect on anti-inflammatory properties of MAG-EPA in DSS rats.

Cytosolic phospholipase A2 α has a crucial role in the pathogenesis of DSS-induced colitis in mice

Colitis, an inflammation of the colon, is a well-characterized massive tissue injury. Cytosolic phospholipase A2 α (cPLA2 α) upregulation plays an important role in the development of several inflammatory diseases. The aim of the present study was to define the role of cPLA2 α upregulation in the development of colitis. We used a mouse model of dextran sulfate sodium induced colitis. Immunoblotting analysis showed that cPLA2 α and NF-κB were upregulated and activated in the colon from day 2 of colitis induction. This molecular event preceded the development of the disease, as determined by Disease Activity Index score, body weight, colon length, and the expression of colonic inflammatory markers, including neutrophil infiltration detected by myeloperoxidase and by NIMP-R14, ICAM-1, COX-2, iNOS upregulation and LTB4 and TNF-α secretion. Prevention of cPLA2 α upregulation and activity in the colon by i.v. administration of specific antisense oligonucleotides against cPLA2 α 1 day prior and every day of exposure to dextran sulfate sodium significantly impeded the development of the disease and prevented NF-κB activation, neutrophils infiltration into the colonic mucosa, and expression of proinflammatory proteins in the colon. Our results demonstrate a critical role of cPLA2 α upregulation in inflammation and development of murine colitis.

Effect of Astragalus polysaccharide and its sulfated derivative on growth performance and immune condition of lipopolysaccharide-treated broilers

This study evaluates the immunomodulating activities of Astragalus polysaccharide (APS) and sulfated APS (SAPS) in LPS-infected broiler chicks. SAPS was derived using the classic chlorosulfonic acid-pyridine method. On day 16, the birds were injected intramuscularly with 0.5 mL of either saline, APS (4 or 8 mg/kg of body weight (BW), shorten as APS-4 or APS-8) or SAPS (4 or 8 mg/kg of BW, shorten as SAPS-4 or SAPS-8) once a day for three successive days. On days 19 and 20, the birds were intraperitoneally injected with 0.5 mL of LPS (1mg/kg of BW). Saline was used as blank control. Compared with the blank control, LPS-treated birds showed lower daily body weight gain (BWG), average daily feed intake (ADFI), villus height and intraepithelial lymphocytes (IEL) number in jejunum, and higher feed conversion ratio (FCR, feed:gain), spleen index, plasma NO concentration, blood heterophil:lymphocyte (H:L) ratio, and the production of NO in the blood T lymphocytes. Compared with the LPS group, birds in APS-4, SAPS-4 and SAPS-8 groups showed decreased FCR (P<0.05). Moreover, SAPS increased BWG and jejunal villus height (P<0.05) at 8 mg/kg BW. Plasma NO concentration was lower in APS-8 group than that in LPS group (P<0.05). Both APS-8 and SAPS-8 treatments elevated the number of jejunal IEL (P<0.05), and decreased blood H:L ratio (P<0.05), respectively. Administration of APS or SAPS did not affect the ADFI, immune organ index, crypt depth and mucosal thickness of the jejunum, and the number of goblet cell. Our findings suggested that APS and SAPS possessed dose-dependent growth-promoting and immunomodulating effect, and was a potential development direction for immunomodulator under early LPS stimulation condition.

Temporal and spatial dependence of inflammatory biomarkers and suppression by fluvastatin in dextran sodium sulfate-induced rat colitis model

BACKGROUND

Dextran sodium sulfate (DSS)-induced colitis in rats is widely used as an experimental model for elucidating the etiology of ulcerative colitis (UC) and developing its novel remedy. We investigated the temporal and spatial changes in inflammatory mediators such as tumor necrosis factor (TNF)-α and inducible nitric oxide synthase (iNOS) in the regions of rectum and distal colon and examined whether statins, which were designed to lower plasma cholesterol levels, influenced those mediators.

METHODS

Colitis was induced in rats by oral administration of 5 % DSS for 5 days, followed by 2 % DSS for 10 days. 5 % DSS rats were treated with fluvastatin (20 mg/kg) concomitantly for 5 days. The expression of inflammatory mediators of a sequence of four regions in rectum (R) and distal colon (D0, D1, and D2) was determined by quantitative RT-PCR.

RESULTS

The peak of colitic damage, which was confirmed clinically and histopathologically, was found on days 4-6. The expression of TNF-α, iNOS, cytokine-induced neutrophil chemoattractant-1, interleukin (IL)-1β, and IL-6 mRNA increased in R time dependently, showing the peak on days 4-6, and then decreased thereafter. The levels of mRNAs reduced from R to D0, D1, and D2 region dependently. Fluvastatin decreased the expression of these markers in addition to the prevention of DSS-induced damage.

CONCLUSIONS

Results demonstrated that the expression of inflammatory biomarkers had time and region specificity and was markedly inhibited by fluvastatin. To obtain a precise drug effect for UC, it is important to elucidate the temporal and spatial dependence of inflammatory biomarkers in DSS colitis model.

Protective effect of hydroalcoholic olive leaf extract on experimental model of colitis in rat: involvement of nitrergic and opioidergic systems

The aim of the present study is to investigate the possible protective effect of dry olive leaf extract (OLE) against acetic acid-induced ulcerative colitis in rats, as well as the probable modulatory effect of nitrergic and opioidergic systems on this protective impact. Olive leaf extract was administered (250, 500 and 750 mg/kg) orally for two successive days, starting from the colitis induction. To assess the involvement of nitrergic and opioidergic systems in the possible protective effect of OLE, L-NG-Nitroarginine Methyl Ester (10 mg/kg) and naltrexone (5 mg/kg) intraperitoneal (i.p.) were applied 30 min before administration of the extract for two successive days, respectively. Colonic status was investigated 48 h following induction through macroscopic, histological and biochemical analyses. Olive leaf extract dose-dependently attenuated acetic acid-provoked chronic intestinal inflammation. The extract significantly reduces the severity of the ulcerative lesions and ameliorated macroscopic and microscopic scores. These observations were accompanied by a significant reduction in the elevated amounts of TNF-α and interlukin-2 markers. Moreover, both systems blockage reversed protective effects of OLE in the rat inflammatory bowel disease model. These finding demonstrated, for the first time, a possible role for nitrergic and opioidergic systems in the aforementioned protective effect, and the extract probably exerted its impact increasing nitric oxide and opioid tones.

Trp53 deficiency protects against acute intestinal inflammation

The p53 protein has not only important tumor suppressor activity but also additional immunological and other functions, whose nature and extent are just beginning to be recognized. In this article, we show that p53 has a novel inflammation-promoting action in the intestinal tract, because loss of p53 or the upstream activating kinase, ATM, protects against acute intestinal inflammation in murine models. Mechanistically, deficiency in p53 leads to increased survival of epithelial cells and lamina propria macrophages, higher IL-6 expression owing to enhanced glucose-dependent NF-κB activation, and increased mucosal STAT3 activation. Blockade or loss of IL-6 signaling reverses the protective effects of p53 deficiency. Conversely, IL-6 treatment protects against acute colitis in a manner dependent on STAT3 signaling and induction of cytoprotective factors in epithelial cells. Together, these results indicate that p53 promotes inflammation in the intestinal tract through suppression of epithelium-protective factors, thus significantly expanding the spectrum of physiological and immunological p53 activities unrelated to cancer formation.

Activated eosinophils in association with enteric nerves in inflammatory bowel disease

Enteric neural dysfunction leads to increased mucous production and dysmotility in inflammatory bowel disease (IBD). Prior studies have shown that tissue eosinophilia is related to disease activity. We hypothesized that interactions between eosinophils and nerves contribute to neural dysfunction in IBD. Tissue from patients with intractable IBD, endoscopic biopsies from patients with steroid responsive IBD, both when active and quiescent, and control tissue were studied. Immunohistochemical studies showed that eosinophils localize to nerves in the mucosal layer of patients with Crohn’s disease (CD) (p<0.001) and ulcerative colitis (UC), (p<0.01). Eosinophils localized to substance P and choline acetyltransferase (ChAT) immunostained nerves. Real time PCR of laser capture micro-dissected enteric ganglia demonstrated Intercellular Adhesion Molecule 1 (ICAM-1) mRNA was increased 7-fold in UC (n = 4), (p = 0.03), and 10-fold in CD (n = 3), (p = 0.05). Compared with controls, eotaxin-3 (CCL-26) mRNA was increased 9-fold in UC (p = 0.04) and 15-fold in CD (p = 0.06). Eosinophil numbers correlated with disease activity, while deposition of major basic protein (MBP) and eosinophil Transforming Growth Factor β -1 (TGFβ-1) expression were seen in therapeutically responsive disease. These data indicate a significant localization of eosinophils to nerves in IBD, mediated through neurally expressed ICAM-1 and eotaxin-3. This cell/neural interaction may influence the function of nerves and contribute to symptoms in IBD.

Protective effect of Bauhinia tomentosa on acetic acid induced ulcerative colitis by regulating antioxidant and inflammatory mediators

Inflammatory bowel diseases (IBD), including Crohn's disease and Ulcerative colitis (UC), are life-long and recurrent disorders of the gastrointestinal tract with unknown etiology. The present study is designed to evaluate the ameliorative effect of Bauhinia tomentosa during ulcerative colitis (UC). Three groups of animals (n=6) were treated with B. tomentosa (5, 10, 20 mg/kg B.wt respectively) for 5 consecutive days before induction of UC. UC was induced by intracolonic injection of 3% acetic acid. The colonic mucosal injury was assessed by macroscopic scoring and histological examination. Furthermore, the mucosal content of lipid peroxidation (LPO), reduced glutathione (GSH), nitric oxide (NO), glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity confirms that B. tomentosa could significantly inhibit colitis in a dose dependent manner. The myeloperoxidase (MPO), tumor necrosis factor (TNF-α), inducible nitric oxide synthase (iNOS) expression studies and lactate dehydrogenase (LDH) assay also supported that B. tomentosa could significantly inhibit experimental colitis. The effect was comparable to the standard drug sulfasalazine. Colonic mucosal injury parallels with the result of histological and biochemical evaluations. The extracts obtained from B. tomentosa possess active substances, which exert marked protective effects in acute experimental colitis, possibly by regulating the antioxidant and inflammatory mediators.

Nitric oxide as a mediator of inflammation?-You had better believe it

Nitric oxide has enigmatic qualities in inflammation. In order to appreciate the precise contributions of nitric oxide to a pathophysiological process, one must account for enzyme source, coproduction of oxidants and antioxidant defences, time, rate of nitric oxide production, cellular source, peroxynitrite formation and effects on DNA (mutagenesis/apoptosis). We contend that there is ample evidence to consider nitric oxide as a molecular aggressor in inflammation, particularly chronic inflammation. Therapeutic benefit can be achieved by inhibition of inducible nitric oxide synthase and not the donation of additional nitric oxide. Furthermore, there is growing appreciation that nitric oxide and products derived thereof, are critical components linking the increased incidence of cancer in states of chronic inflammation.

p53 mediates TNF-induced epithelial cell apoptosis in IBD

Chronic ulcerative colitis (CUC) is characterized by increased intestinal epithelial cell (IEC) apoptosis associated with elevated tumor necrosis factor (TNF), inducible nitric oxide synthase (iNOS), and p53. We previously showed that p53 is increased in crypt IECs in human colitis and is needed for IEC apoptosis in chronic dextran sulfate sodium-colitis. Herein, we examined the roles of TNF and iNOS in regulating p53-induced IEC apoptosis in CUC. The IEC TUNEL staining, caspases 3, 8, and 9, and p53 protein levels, induced by anti-CD3 monoclonal antibody (mAb) activation of T cells, were markedly reduced in TNF receptor 1 and 2 gene knockout mice. Induction of IEC apoptosis correlated with increased p53, which was attenuated in iNOS(-/-) mice. IEC p53 levels and apoptosis were reduced in IL-10(-/-) colitic mice treated with neutralizing TNF mAb and the iNOS inhibitor, aminoguanidine, further suggesting that TNF and iNOS are upstream of p53 during colitis-induced IEC apoptosis. IEC apoptosis and p53 levels were assessed in control versus untreated or anti-TNF-treated CUC patients with equivalent levels of inflammation. Data indicated that IEC apoptosis and p53 levels were clearly higher in untreated CUC but markedly reduced in patients treated with anti-TNF mAb. Therefore, TNF-induced iNOS activates a p53-dependent pathway of IEC apoptosis in CUC. The inhibition of IEC apoptosis may be an important mechanism for mucosal healing in anti-TNF-treated CUC patients.

Cellular and molecular mechanisms of intestinal fibrosis

Fibrosis is a chronic and progressive process characterized by an excessive accumulation of extracellular matrix (ECM) leading to stiffening and/or scarring of the involved tissue. Intestinal fibrosis may develop in several different enteropathies, including inflammatory bowel disease. It develops through complex cell, extracellular matrix, cytokine and growth factor interactions. Distinct cell types are involved in intestinal fibrosis, such as resident mesenchymal cells (fibroblasts, myofibroblasts and smooth muscle cells) but also ECM-producing cells derived from epithelial and endothelial cells (through a process termed epithelial- and endothelial-mesenchymal transition), stellate cells, pericytes, local or bone marrow-derived stem cells. The most important soluble factors that regulate the activation of these cells include cytokines, chemokines, growth factors, components of the renin-angiotensin system, angiogenic factors, peroxisome proliferator-activated receptors, mammalian target of rapamycin, and products of oxidative stress. It soon becomes clear that although inflammation is responsible for triggering the onset of the fibrotic process, it only plays a minor role in the progression of this condition, as fibrosis may advance in a self-perpetuating fashion. Definition of the cellular and molecular mechanisms involved in intestinal fibrosis may provide the key to developing new therapeutic approaches.

Intrarectal nitric oxide administration prevents cellular infiltration but not colonic injury during dextran sodium sulfate colitis

BACKGROUND

During inflammation in the gastrointestinal tract, the production of nitric oxide (NO) is mediated by the mucosal conversion of L-arginine. Recently, it was shown that the gut microbiota can also produce NO.

AIMS

The effect of gut luminal NO on inflammatory processes of an experimental colitis mice model was investigated by administrating NO directly to the colon, mimicking microbial NO production.

METHODS

Twenty-four mice received daily intrarectal treatment with a NO donor in 2 doses and 8 mice were treated with placebo. Starting 1 day later, 18 of these mice were fed ad libitum with 4% of dextran sodium sulfate (DSS) in their drinking water to induce colitis. At day 6, histopathology (both the inflammation and damage score), myeloperoxidase (MPO)-activity, colon length and colonic permeability were evaluated.

RESULTS

Co-administration of NO during DSS exposure inhibited the induction of an increasing colonic MPO-activity. This protective effect of NO was confirmed by the histological inflammation score showing a similar trend. The colonic permeability was restored when very low levels of NO were administered to the DSS-mice. On the other hand, the colon length of the NO-treated DSS-mice was negatively correlated with the NO dose and the histological damage score was not improved.

CONCLUSIONS

Our results indicate that intrarectal administration of NO has clear anti-inflammatory effects in experimental colitis, but does not prevent colonic damage. Therefore, NO-producing microorganisms in the gut lumen should be accounted as a modulating process during colitis.

Effects of curcumin and Ginkgo biloba on matrix metalloproteinases gene expression and other biomarkers of inflammatory bowel disease

Treatment of inflammatory bowel disease (IBD) by synthetic active ingredients leads to many side effects. The objective of this study was to manage IBD using natural products as curcumin and Ginkgo biloba. Rats were divided into four groups (control, IBD, curcumin treated, and ginkgo treated). Inflammation was assessed by determination of myeloperoxidase, matrix metalloproteinases, metalloproteinase-1 inhibitor, nitric oxide, hydroxyproline, tumor necrosis factor-alpha, ceruloplasmin, and histopathological scoring. IBD induction significantly increased all measured parameters. Treated groups had significantly lower levels when compared with the IBD group. In conclusion, curcumin and ginkgo were effective in prevention and treatment of IBD.

Inhibition of interferon-γ-induced nitric oxide production by 10-hydroxy-trans-2-decenoic acid through inhibition of interferon regulatory factor-8 induction

10-Hydroxy-trans-2-decenoic acid (10H2DA) is a major lipid component of royal jelly, a honey bee secretion used to nourish the queen bee and young larvae. In this study, we examined the effect of 10H2DA on interferon (IFN)-γ-induced nitric oxide (NO) production. IFN-γ-induced NO production and activation of the inducible NO synthase promoter were significantly inhibited by 10H2DA. IFN-γ-induced phosphorylation of signal transducer and activator of transcription-1 was not affected by 10H2DA. In contrast, IFN-γ-induced tumor necrosis factor (TNF)-α production and nuclear factor (NF)-κB activation were inhibited by 10H2DA. IFN-γ-mediated induction of interferon regulatory factor (IRF)-8, but not IRF-1, was also inhibited by 10H2DA. IFN-γ-induced TNF-α production followed by activation of NF-κB is known to be essential for NO production. Together, 10H2DA inhibited IFN-γ-induced NO production by inhibiting IRF-8 induction and TNF-α production. 10H2DA might modulate IFN-γ-mediated cellular responses by inhibiting the induction of IRF-8 and IRF-8-dependent genes.

Lack of transketolase-like (TKTL) 1 aggravates murine experimental colitis

Transketolase-like (TKTL) 1 indirectly replenishes NADPH preventing damage induced by reactive oxygen species (ROS) formed upon intestinal inflammation. We investigated the function of TKTL1 during murine colitis and ROS detoxification for prevention of tissue damage. Mucosal damage in TKTL1(-/-) and wild-type (WT) mice was assessed by miniendoscopy and histology during dextran sodium sulfate (DSS) colitis. mRNA levels of interferon (IFN)-γ, inducible nitric oxide synthase (iNOS), interleukin (IL)-6, tumor necrosis factor (TNF), transketolase (TKT), and TKTL2 were determined by PCR and/or Western blotting. To assess oxidative and nitrosative stress nitrosylation, carbonylation and antioxidative enzymes catalase (Cat), superoxide dismutase 1 and 2, as well as glutathione (GSH) were determined. Myeloperoxidase (MPO) was determined for assessment of tissue neutrophils. TKTL1 knockout or DSS treatment did not influence TKT and TKTL2 mRNA or protein expression. Mucosal damage was significantly increased in TKTL1(-/-) mice indicated by miniendoscopy as well as a significantly shorter colon and more severe histological scores compared with WT mice during DSS colitis. This was associated with higher mRNA levels of IFN-γ, iNOS, IL-6, and TNF. In addition, iNOS protein expression was significantly enhanced in TKTL1(-/-) mice as well as MPO activity. Protein modification by nitric oxide (nitrotyrosine) was induced in TKTL1(-/-) mice. However, introduction of carbonyl groups by ROS was not induced in these mice. The expression of SOD1, SOD2, Cat, as well as GSH content was not significantly changed in TKTL1(-/-) mice. We conclude that induced colitis in TKTL1(-/-) mice was more severe compared with WT. This indicates a role of TKTL1 during mucosal repair and restoration.

A melon pulp concentrate rich in superoxide dismutase reduces stress proteins along the gastrointestinal tract of pigs

OBJECTIVE

A melon (Cucumis melo LC.) pulp concentrate (MPC) rich in superoxide dismutase (SOD) activity was tested for its ability to decrease stress protein expressions along the gastrointestinal tract in a swine model.

METHODS

Pig sextuplets weaned at 21 d of age were selected from among six litters (n = 36). After a 2-d fasting period, the pigs were fed at similar levels of intake of the control, MPC1, and MPC2 diets, which provided 0, 12.5, and 50 IU of added SOD per kilogram of food, respectively. One triplet of pigs per litter was slaughtered at 7 d and the second triplet at 14 d after weaning. SOD, catalase, and digestive enzymes were determined enzymatically and stress protein expressions by western blotting.

RESULTS

Plasma SOD increased with MPC dose at day 14 (P < 0.05). Mucosal weights in the proximal and mid small intestine were lower at day 14 (P < 0.05), cecum tissue weight was greater (P < 0.05), and sucrase-specific activity in mid and distal small intestine mucosa was lower (P = 0.05) in the MPC2 group than in the control group. MPC supplementation essentially decreased (P < 0.05 to P < 0.001) stress proteins in the stomach (all), the mid small intestine (heat-shock protein-27, neuronal nitric oxide synthase) and the colon (heat-shock protein-70, neuronal nitric oxide synthase).

CONCLUSION

A SOD-rich MPC provided at the dose of 50 IU/kg of food for up to 12 d was effective in lowering the level of stress proteins along the gastrointestinal tract of pigs after weaning.

Genes regulated by Nkx2-3 in siRNA-mediated knockdown B cells: implication of endothelin-1 in inflammatory bowel disease

Nkx2-3 gene variants are strongly associated with inflammatory bowel disease (IBD) and its expression is up-regulated in Crohn's disease (CD). However, the nature of its role underlying IBD pathogenesis is unknown. We investigated the genes regulated by Nkx2-3 using cDNA microarray. A small interfering RNA (siRNA)-mediated knockdown of Nkx2-3 in a B cell line from a CD patient was generated. Gene expression was profiled on high-density cDNA microarrays representing over 25,000 genes. Ingenuity pathway analysis (IPA) was used to identify gene networks according to biological functions and associated pathways. Expression profiling analysis by cDNA microarray showed that 125 genes were regulated by Nkx2-3 knockdown (fold change >or=3.0, p<0.01), among which 51 genes were immune and inflammatory response genes. Microarray results were validated by RT-PCR and further confirmed in a B cell line expressing siRNA of Nkx2-3 from an additional CD patient. The results showed that Nkx2-3 was up-regulated (p<0.05) and EDN1 was down-regulated (p<0.05) in B cell lines from CD patients. mRNA expression levels of Nkx2-3 were negatively correlated with those of EDN1 (r=-0.6044, p<0.05). EDN1 was also down-regulated in intestinal tissues from UC patients (p<0.05). Our present results demonstrate that a decrease in Nkx2-3 gene expression level can profoundly alter the expression of genes and cellular functions relevant to the pathogenesis and progression of IBD, such as EDN1.

An insight into the possible protective effect of pyrrolidine dithiocarbamate against lipopolysaccharide-induced oxidative stress and acute hepatic injury in rats

Lipopolysaccharide (LPS) is a major cell wall molecule of Gram-negative bacteria known to stimulate the synthesis and secretion of several toxic metabolites, such as reactive oxygen species. In this study, the effect of pyrrolidine dithiocarbamate (PDTC), an antioxidant with nuclear factor-κB inhibitor activity, was evaluated in LPS-induced oxidative stress and acute hepatic injury in rats. Animals were pretreated for 3 consecutive days with PDTC (200 mg/kg/day, i.p.) or saline and animals were then challenged with LPS (6 mg/kg, i.p.) or saline. Six hours after LPS injection, animals were decapitated and blood and liver samples were collected to assess the chosen biochemical parameters. Saline-pretreated animals challenged with LPS revealed extensive liver damage, as evidenced by increases in serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma glutamyl transferase (γ-GT). Also, LPS treatment resulted in significant increases in serum lactate dehydrogenase (LDH), tumor necrosis factor-alpha (TNF-α) and nitrite levels. Furthermore, LPS challenge caused oxidative stress as indicated by an increase in hepatic lipid peroxidation measured as thiobarbituric acid reactive substances (TBARS) and a decrease in hepatic reduced glutathione concentration (GSH) as well as decreased activities of superoxide dismutase (SOD) and catalase in hepatic tissues. The administration of PDTC prior to LPS challenge resulted in improved liver functions as evidenced by the decline in serum AST, ALT, γ-GT levels and reduction in serum LDH, TNF-α and nitrite levels. Moreover, PDTC reduced the chosen lipid peroxidation marker, TBARS and increased GSH concentration, and SOD and catalase activities in hepatic tissues. These results indicate that PDTC may be a useful pharmacological agent in alleviating LPS-induced oxidative stress and acute hepatic injury.

TNF-alpha modulates iNOS expression in an experimental rat model of indomethacin-induced jejunoileitis

Multiple mucosal immune factors, such as TNF-alpha and IL-1beta, are thought to be key mediators involved in inflammatory bowel disease. We evaluated the role of the pro-inflammatory cytokine TNF-alpha on nitric oxide synthase (NOS) expression in indomethacin-induced jejunoileitis in rats. Jejunoileitis was induced in rats with subcutaneous injections of indomethacin (7.5 mg/kg) 24 h apart for two consecutive days, and animals were randomized into four groups. Group 1 received only indomethacin. Group 2 was treated with a daily dose of phosphodiesterase (PDE) inhibitor (theophylline or pentoxifylline) by oral gavage for 2 days before and 4 days after indomethacin. Group 3 received a single dose of anti-TNF-alpha monoclonal antibody (TNF-Ab, IP) 30 min before indomethacin. Group 4 was treated with 1 h hyperbaric oxygenation (HBO(2)) for 5 days after indomethacin. Rats were sacrificed at 12 h or 4 days after final indomethacin injection. PDE inhibitor, TNF-Ab, or HBO(2) treatment significantly decreased indomethacin-induced ulceration, myeloperoxidase activity, and disease activity index. Although indomethacin significantly increased serum TNF-alpha and nitrate/nitrite (NOx) concentrations above control values at 12 h, inducible NOS (iNOS) expression was detected only at day 4. Serum IL-1beta levels did not change at 12 h but increased 4-fold after 4 days. Indomethacin had no effect on constitutive NOS. Treatment with PDE inhibitor, TNF-Ab, or HBO(2) significantly reduced serum/tissue TNF-alpha, IL-1beta, NOx, and iNOS expression. Our data show TNF-alpha plays an early pro-inflammatory role in indomethacin-induced jejunoileitis. Additionally, down-regulation of NOx by PDE inhibitors, TNF-Ab, or HBO(2) suggests that TNF-alpha modulates iNOS expression.

Inflammatory bowel disease: a model of chronic inflammation-induced cancer

Chronic inflammation is a well-recognized risk factor for the development of human cancer. Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, is a typical longstanding inflammatory disease of the colon with increased risk for the development of colorectal carcinoma. Several molecular events involved in chronic inflammatory process may contribute to multistage progression of human cancer development, including the overproduction of reactive oxygen and nitrogen species, overproduction/activation of key arachidonic acid metabolites and cytokines/growth factors, and immunity system dysfunction. Multiple animal models of IBD have been established, and in general, these models can be mainly categorized into chemically induced, genetically engineered (transgenic or gene knock-out), spontaneous, and adoptive transferring animal models. This chapter mainly focuses on (1) epidemiologic and molecular evidence on IBD and risk of colorectal cancer, (2) molecular pathogenesis of IBD-induced carcinogenesis, and (3) modeling of IBD-induced carcinogenesis in rodents and its application.

Effects of N-acetylcysteine plus mesalamine on prostaglandin synthesis and nitric oxide generation in TNBS-induced colitis in rats

The aim of the present studies was to examine mechanisms by which the rectally administered combination of N-acetylcysteine (NAC) plus mesalamine (5-ASA) affects inducers of inflammation to promote mucosal healing and reduce tissue inflammation in chemically (trinitrobenzene sulfonic acid, TNBS) induced colitis in rats. Experimental findings demonstrate that dual therapy with NAC plus 5-ASA was superior to individual agents in reducing histological measures of colitis. NAC alone and in combination with 5-ASA suppressed COX2 gene expression and prostaglandin E(2) (PGE(2)) levels to control values. Furthermore, NAC plus 5-ASA reduced nitrate generation, an expression of inducible nitric oxide synthase (iNOS) activity, to basal levels and these results were significantly lower than those observed with either NAC or 5-ASA alone. In conclusion, these results indicate that NAC plus 5-ASA exerts therapeutic benefit, in part by countering the actions of PGE(2) and the deleterious effects of oxidative and nitrosative stress induced by TNBS colitis.

Nitric oxide and TNF-alpha trigger colonic inflammation and carcinogenesis in Helicobacter hepaticus-infected, Rag2-deficient mice

Recombinase-activating gene-2-deficient (Rag2(-/-)) mice lacking functional lymphocytes provide a useful model of chronic inflammatory bowel disease-emulating events in human colon cancer. Infection of Rag2(-/-) mice with Helicobacter hepaticus led to accumulation of macrophages and neutrophils in the colon, a process temporally related to up-regulation of tissue inducible nitric oxide synthase (iNOS) expression at the site of infection and increased nitric oxide (NO) production, as evidenced by urinary excretion of nitrate. Progressive development of increasingly severe inflammation, hyperplasia, dysplasia, and cancer accompanied these changes. Concurrent administration of an iNOS inhibitor prevented NO production and abrogated epithelial pathology and inhibited the onset of cancer. The presence of Gr-1(+) neutrophils and elevated tumor necrosis factor-alpha (TNF-alpha) expression in colon were required for increased iNOS expression and cancer, whereas interleukin-10 (IL-10) down-regulated TNF-alpha and iNOS expression and suppressed cancer. Anti-inflammatory CD4(+) regulatory lymphocytes also down-regulated iNOS and reduced cancer formation. Collectively, these results confirm essential roles for inflammation, increased TNF-alpha expression, and elevated NO production in colon carcinogenesis.

The effect of iNOS inhibitors and hyperbaric oxygen treatment in a rat model of experimental colitis

AIM

Our aim was to investigate the effectiveness of aminoguanidine (AMG), an inducible nitric oxide synthase inhibitor, and hyperbaric oxygen (HBO) treatment in an experimental colitis model.

METHODS

We induced colitis in rats. In the control group, we applied 2 ml serum physiologic intraperitoneally for 7 days. In the HBO group, 100% oxygen at 2.4 atm pressure was applied for 7 days. In the AMG group, 100 mg/kg AMG was applied intraperitoneally for 7 days. In the HBO + AMG group, HBO and AMG were applied, respectively. At the end of 7 days, rats were sacrificed and the distal 10 cm part of colon was examined macro- and microscopically.

RESULTS

Severity of colitis and NO activities were reduced by AMG, HBO, and HBO + AMG application. There was histologically significant improvement, especially in the HBO + AMG group.

CONCLUSIONS

Both HBO and AMG were significantly effective in preventing weight loss, reducing NO activities, and severity of colitis, when comparing HBO and AMG separately.

Targeted deletion of neuropeptide Y (NPY) modulates experimental colitis

Background

Neurogenic inflammation plays a major role in the pathogenesis of inflammatory bowel disease (IBD). We examined the role of neuropeptide Y (NPY) and neuronal nitric oxide synthase (nNOS) in modulating colitis.

Methods

Colitis was induced by administration of dextran sodium sulphate (3% DSS) or streptomycin pre-treated Salmonella typhimurium (S.T.) in wild type (WT) and NPY (NPY^−/−) knockout mice. Colitis was assessed by clinical score, histological score and myeloperoxidase activity. NPY and nNOS expression was assessed by immunostaining. Oxidative stress was assessed by measuring catalase activity, glutathione and nitrite levels. Colonic motility was assessed by isometric muscle recording in WT and DSS-treated mice.

Results

DSS/S.T. induced an increase in enteric neuronal NPY and nNOS expression in WT mice. WT mice were more susceptible to inflammation compared to NPY^−/− as indicated by higher clinical & histological scores, and myeloperoxidase (MPO) activity (p<0.01). DSS-WT mice had increased nitrite, decreased glutathione (GSH) levels and increased catalase activity indicating more oxidative stress. The lower histological scores, MPO and chemokine KC in S.T.-treated nNOS^−/− and NPY^−/−/nNOS^−/− mice supported the finding that loss of NPY-induced nNOS attenuated inflammation. The inflammation resulted in chronic impairment of colonic motility in DSS-WT mice. NPY –treated rat enteric neurons in vitro exhibited increased nitrite and TNF-α production.

Conclusions

NPY mediated increase in nNOS is a determinant of oxidative stress and subsequent inflammation. Our study highlights the role of neuronal NPY and nNOS as mediators of inflammatory processes in IBD.

Luminal antioxidants enhance the effects of mesalamine in the treatment of chemically induced colitis in rats

Previous experiments in rats with chemically induced colitis have shown that the antioxidant N-acetylcysteine plus mesalamine (5-ASA) exerted a significantly greater therapeutic effect in promoting mucosal healing when compared to either agent alone. The aims of the present study were to compare the effects of three antioxidants plus mesalamine vs. 5-ASA alone in treatment of colitis induced by trinitrobenzene sulfonic acid (TNBS) in rats.

METHODS

Three days following induction of TNBS colitis, rats received 8 days of rectal therapy with 5-ASA, or 5-ASA plus vitamin C (ascorbic acid), 5-ASA plus phenyl butylnitrone (PBN) and 5-ASA plus vitamin E (alpha-tocopherol). Distal colonic tissues were examined for microscopic colitis and myeloperoxidase (MPO) activity.

RESULTS

Global assessments of microscopic colitis induced by TNBS indicated that 5-ASA alone significantly changed colonic injury by -31%. Combination therapy with ascorbic acid plus 5-ASA or alpha-tocopherol plus 5-ASA caused further significant change in TNBS colitis by -65 and -82%, respectively. Each of these values was significantly below scores observed with 5-ASA as monotherapy. Reduction in colitis with PBN plus 5-ASA was not different from 5-ASA alone. MPO activity was decreased significantly in response to monotherapy with 5-ASA and each of the antioxidants plus 5-ASA when compared to TNBS. alpha-Tocopherol plus 5-ASA, however, was the only treatment strategy that reduced significantly MPO activity below that recorded for 5-ASA alone. In conclusion, our results indicate that antioxidants other than N-acetylcysteine significantly enhance the therapeutic effectiveness of 5-ASA in the treatment of TNBS colitis. alpha-Tocopherol plus 5-ASA exerted profound anti-inflammatory and reparative effects upon colitis induced by TNBS.

Decreased development of necrotizing enterocolitis in IL-18-deficient mice

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease predominantly of prematurely born infants, characterized in its severest from by extensive hemorrhagic inflammatory necrosis of the distal ileum and proximal colon. Proinflammatory cytokines have been implicated in the development of NEC, and we have previously shown that IL-18 is significantly elevated in the well-established neonatal rat model of NEC. To determine whether IL-18 contributes to intestinal pathology in NEC, we subjected IL-18 knockout mice to the protocol used to develop experimental NEC in newborn rats. Newborn B6.129P2-Il18(tm1Aki)/J (NEC IL-18(-/-)) and wild-type (NEC WT) mice were hand fed every 3 h with cow's milk-based formula and exposed to asphyxia and cold stress twice daily. After 72 h, animals were killed and distal ileum and liver were removed. Disease development was determined via histological changes in the ileum as scored by a blinded evaluator. The number of TNF-alpha-, IL-12-, and IL-1beta-positive cells and macrophages were determined in both ileum and liver via immunohistology. IkappaB-alpha and IkappaB-beta were determined from protein extracts from both ileum and liver using Western blot analysis. The incidence and severity of NEC was significantly reduced in NEC IL-18(-/-) mice compared with NEC WT. Furthermore, mean ileal macrophages and hepatic IL-1beta were significantly reduced in IL-18(-/-) mice subjected to the NEC protocol. There were no statistically significant changes in Kupffer cells, hepatic TNF-alpha, ileal IL-1beta, or IL-12. IkappaB-alpha and IkappaB-beta were significantly increased in NEC IL-18(-/-) mice ileum and liver, respectively. These results confirm that IL-18 plays a crucial role in experimental NEC pathogenesis.

5-aminosalicylic acid improves indomethacin-induced enteropathy by inhibiting iNOS transcription in rats

Nitric oxide has been implicated in the pathogenic mechanism of inflammatory bowel disease states. We evaluated indomethacin-induced enteropathy in rats, in relation to the expression of the inducible isoform of NO synthase (iNOS) using aminosalicylic acid (5-ASA), its isomer 4-ASA (10 or 50 mg/kg/day, po), and dexamethasone, an iNOS transcription inhibitor (3 mg/kg/day, sc). Enteropathy was induced by indomethacin (7.5 mg/kg/day, sc) for two days and the small intestine was examined for lesions over the next 14 days. Indomethacin-induced small-intestinal ulcer size, mucosal myeloperoxidase activity, iNOS expression and serum nitrite/nitrate levels were maximally increased by day 4 and gradually decreased by day 14. Treatment with 5-ASA, but not 4-ASA, decreased indomethacin-induced ulcer length, myeloperoxidase activity, serum nitrite/nitrate levels and iNOS expression at day 4. Dexamethasone had a greater effect than 5-ASA in reducing myeloperoxidase activity and ulcer length by 26 and 32%, respectively. Dexamethasone also reduced serum nitrate/nitrite and iNOS expression to their basal levels. In conclusion, inhibition of iNOS expression by 5-ASA appears to be associated with diminished intestinal ulceration in indomethacin-induced enteropathy.

Early bacterial dependent induction of inducible nitric oxide synthase (iNOS) in epithelial cells upon transfer of CD45RB(high) CD4(+) T cells in a model for experimental colitis

BACKGROUND

Both the role of inducible nitric oxide synthase (iNOS) in the development of inflammatory bowel disease (IBD) as well as the molecular details governing its mucosal induction remain unclear.

METHODS

In the present study we evaluated the role of the residing intestinal microflora in the induction of epithelial iNOS upon transfer of CD45RB(high) CD4(+) T cells to SCID mice. CB-17 SCID mice were reared with conventional flora (CNV) or germfree CB-17 SCID mice were monoassociated with Helicobacter muridarum, act A(-) mutant Listeria monocytogenes, segmented filamentous bacteria (SFB), or Ochrobactrum anthropi.

RESULTS

Within 2 weeks CNV SCID mice injected with CD45RB(high) CD4(+) T cells showed a focal, epithelial iNOS expression on the apical site of villi that preceded the infiltration of CD4(+) T cells and cytokine production followed by extension of this expression to the entire surface along the whole crypt axis as the colitis progressed. SCID mice monoassociated with H. muridarum developed a severe colitis and showed high epithelial iNOS expression. CNV-SCID mice without T cells and SCID mice monoassociated with SFB did not show any iNOS expression, whereas SCID mice monoassociated with act A(-) mutant L. monocytogenes and O. anthropi showed some scattered epithelial iNOS staining on the apical site of a few villi, but none of these mice developed colitis.

CONCLUSIONS

These findings demonstrate that the expression of epithelial iNOS is highly bacterium-specific and correlates with the severity of disease, suggesting an important role for this enzyme in the development of IBD.

The intestinal anti-inflammatory effects of the novel agent UR-1505 in the TNBS model of rat colitis are mediated by T-lymphocyte inhibition

UR-1505 is a novel pentafluoropropoxy derivative of salicylic acid, selected from a series of salicylate derivatives, according to their activity as inhibitors of T-lymphocyte activation. This study describes the anti-inflammatory activity of UR-1505 on trinitrobenzenesulphonic acid-induced colitis in rat, an experimental model that resembles to Crohn's disease (CD), as well as its in vitro effects on T-cells and bone marrow-derived macrophages (BMDM) activation. UR-1505 showed intestinal anti-inflammatory effect, associated with reduced colonic levels of TNFalpha and LTB(4), inhibition of the expression of IFNgamma and iNOS, and lower colonic leukocyte infiltration. The in vitro assays revealed that UR-1505 also inhibited T-lymphocyte proliferation and IL-12/IFNgamma production, two of the main pro-inflammatory cytokines involved in the pathogenesis of CD. However, UR-1505 did not modify LPS- nor IFNgamma-induced activation in BMDM. Thus, UR-1505 specifically affects T-cells without modifying the activation of BMDM. In conclusion, the intestinal anti-inflammatory activity of UR-1505 seems to be mediated by a reduction in the recruitment of immune cells to the inflammatory foci, together with the inhibition of T-cell activation. These results suggest that UR-1505 may be an interesting candidate to be explored for the treatment of CD.

The nitric oxide donor LA-419 [S-(6-Nitro-oxi-hexahydro-furo[3,2-b]furan-3-1-il)thioacetate] prevents intestinal dysmotility, bacterial translocation, and inflammation in a rat model of enteritis

Indomethacin induces a chronic model of inflammatory bowel disease (IBD) characterized by spontaneous relapses of inflammation, bacterial translocation, and long-lasting motor disturbances derived from cyclical up-regulated inducible nitric-oxide synthase (iNOS) and sustained down-regulated neuronal NOS (nNOS). The aims of this study were to evaluate whether LA-419 [S-(6-nitro-oxi-hexahydro-furo[3,2-b]furan-3-1-il)thioacetate], a NO-donor drug, could re-establish the normal expression of NOS and, hence, prevent the development of intestinal dysmotility, bacterial translocation, and relapses of inflammation associated to this model. Enteritis was induced in rats by administration of indomethacin with and without treatment with a novel NO-donor: LA-419 (0.5 mg/ml in the drinking water). Inflammatory reaction was evaluated by measuring blood leukocytes, serum tumor necrosis factor, and tissue myeloperoxidase. Intestinal motor activity was evaluated using strain-gauges. Ileal expression of iNOS and nNOS mRNA was determined by reverse transcription-polymerase chain reaction. Bacterial translocation was evaluated in cultures from mesenteric lymph nodes. The indomethacin-induced acute inflammatory reaction was associated with a rise in blood leukocytes and tumor necrosis factor. In the chronic stage, blood leukocyte monitoring allowed the selection of animals in active and inactive phases. Active phase was associated with iNOS up-regulation, high myeloperoxidase levels, hypomotility, and bacterial translocation. In contrast, inactive phase was associated with hypermotility and absence of bacterial translocation. LA-419 treatment restored nitric-oxide synthase isoenzyme expression and prevented the oscillation of both inflammatory and motor parameters that could be cyclically observed in inflamed rats. LA-419 also prevented intestinal dysmotility, bacterial translocation, and relapses of intestinal inflammation. LA-419 might be a novel therapeutic approach to prevent acute inflammatory relapses in patients with IBD.

Colorectal carcinoma development in inducible nitric oxide synthase-deficient mice with dextran sulfate sodium-induced ulcerative colitis

The overproduction of reactive oxygen and nitrogen species (RONS) may play an important role in ulcerative colitis (UC)-associated carcinogenesis. In order to study the role of nitric oxide (NO) in UC-associated colorectal carcinogenesis, the development of colorectal carcinoma was studied using the DSS-induced and iron-enhanced model of chronic UC in inducible nitric oxide synthase (iNOS)-deficient mice. Female wild-type C57BL/6 (iNOS+/+) and iNOS-/- mice were administered 1% DSS (w/v) through the drinking fluid for 15 DSS cycles and fed twofold iron-enriched diet. Colorectal inflammation and mucosal ulceration of moderate severity were observed in both iNOS+/+ and iNOS-/- mice. Similar tumor incidence and multiplicity in the colon were observed that 15 out of 23 (65.2%) iNOS+/+ mice developed colorectal tumors with a tumor multiplicity of 1.47+/-0.17 (mean+/-SE) after 15 DSS cycles, and 13 out of 19 (68.4%) iNOS-/- mice developed colorectal tumors with a tumor multiplicity of 2.08+/-0.21. Histopathologically, the tumors were confirmed to be well-differentiated adenocarcinomas. Nitrotyrosine, an indicator of peroxynitrite-caused protein modification, was detectable by immunohistochemistry in inflammatory cells and epithelial cells of the colon in iNOS+/+ and iNOS-/- mice, and no difference in staining intensity was observed between the two groups. Immunostaining for endothelial NOS (eNOS) was observed in lamina propria macrophages and colonic blood vessels, and eNOS protein levels were increased in the inflamed colon. These results show that there is no difference in UC-associated cancer development in iNOS+/+ and iNOS-/- mice, and suggest that in the absence of iNOS, other factors, such as eNOS, may play a role in nitrosative stress and UC-associated carcinogenesis in this model system.