Nitric oxide in inflammatory bowel disease

Natural products as a source of anti-inflammatory agents associated with inflammatory bowel disease

Accumulating epidemiological and clinical study indicates that inflammation is a significant risk factor to develop various human diseases such as inflammatory bowel disease (IBD), chronic asthma, rheumatoid arthritis, multiple sclerosis, and psoriasis. Suppressing inflammation is therefore important to control or prevent various diseases. Among them, IBD is one of the major problems affecting people worldwide. IBD affects at least one in a thousand persons in many Western countries. Various natural products have been shown to safely suppress pro-inflammatory pathway and control IBD. In vivo and/or in vitro studies indicate that anti-IBD effects of natural products occur by inhibition of the expression of pro-inflammatory cytokines (for example, tumor necrosis factor-α (TNF-α), intercellular adhesion molecule expression and pro-inflammatory mediators (such as inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX2), master transcription factors (such as nuclear factor-κB (NF-κB)), reactive oxygen species (ROS) and by improving the antioxidant activity. In this review, we summarize recent research focused on IBD and the effects that natural products have on IBD factors.

Ethanol extract of Cordyceps militaris grown on germinated soybeans attenuates dextran-sodium-sulfate- (DSS-) induced colitis by suppressing the expression of matrix metalloproteinases and inflammatory mediators

The effect of Cordyceps militaris (CM) grown on germinated soybeans (GSC) in the inflammatory bowel disease (IBD) model was studied. To demonstrate the preventive effect of GSC extract in a dextran-sodium-sulfate- (DSS-) induced acute colitis mouse model, GSC was administered 2 days before DSS coadministration. GSC significantly suppressed DSS-induced disease activity index (DAI) as well as histopathological scores, compared to control or CM-treated group. To elucidate the anti-IBD activity of GSC, we checked the level of matrix metalloproteinases (MMPs) and inflammatory mediators. GSC extract decreased the level of MMP-3 and -9 mRNAs and p53 proteins. The level and activity of LPS-induced MMP-9 were reduced in GSC-treated RAW264.7 cells. It also attenuated the level of inducible nitric oxide synthase (iNOS) and tumor necrosis factor- (TNF-) α mRNAs both in colon tissue and in macrophage cells. These results suggest that GSC can be applied as a protective agent against IBDs.

Inducible NOS mediates CNP-induced relaxation of intestinal myofibroblasts

Contraction of intestinal myofibroblasts (IMF) contributes to the development of strictures and fistulas seen in inflammatory bowel disease, but the mechanisms that regulate tension within these cells are poorly understood. In this study we investigated the role of nitric oxide (NO) signaling in C-type natriuretic peptide (CNP)-induced relaxation of IMF. We found that treatment with ODQ, a soluble guanylyl cyclase (sGC) inhibitor, or N(G)-nitro-L-arginine (L-NNA) or N(G)-monomethyl-L-arginine (L-NMMA), inhibitors of NO production, all impaired the relaxation of human and mouse IMF in response to CNP. ODQ, L-NNA, and L-NMMA also prevented CNP-induced elevations in cGMP concentrations, and L-NNA or L-NMMA blocked CNP-induced decreases in myosin light phosphorylation. IMF isolated from transgenic mice deficient in inducible nitric oxide synthase (iNOS) had reduced relaxation responses to CNP compared with IMF from control mice and were insensitive to the effects of ODQ, L-NNA, and L-NMMA on CNP treatment. Together these data indicate that stimulation of sGC though NO produced by iNOS activation is required for maximal CNP-induced relaxation in IMF.

Curcumin, an active component of turmeric in the prevention and treatment of ulcerative colitis: preclinical and clinical observations

Inflammatory bowel disease (IBD) comprising of ulcerative colitis (UC) and Crohn's disease (CD) is a major ailment affecting the small and large bowel. In clinics, IBD is treated using 5-amninosalicylates, antibiotics, the steroids and immunomodulators. Unfortunately, the long term usages of these agents are associated with undue side effects and compromise the therapeutic advantage. Accordingly, there is a need for novel agents that are effective, acceptable and non toxic to humans. Preclinical studies in experimental animals have shown that curcumin, an active principle of the Indian spice turmeric (Curcuma longa Linn) is effective in preventing or ameliorating UC and inflammation. Over the last few decades there has been increasing interest in the possible role of curcumin in IBD and several studies with various experimental models of IBD have shown it to be effective in mediating the inhibitory effects by scavenging free radicals, increasing antioxidants, influencing multiple signaling pathways, especially the kinases (MAPK, ERK), inhibiting myeloperoxidase, COX-1, COX-2, LOX, TNF-α, IFN-γ, iNOS; inhibiting the transcription factor NF-κB. Clinical studies have also shown that co-administration of curcumin with conventional drugs was effective, to be well-tolerated and treated as a safe medication for maintaining remission, to prevent relapse and improve clinical activity index. Large randomized controlled clinical investigations are required to fully understand the potential of oral curcumin for treating IBD.

Kolaviron, a natural antioxidant and anti-inflammatory phytochemical prevents dextran sulphate sodium-induced colitis in rats

The beneficial effects of kolaviron, a natural biflavonoid from the seeds of Garcinia kola, have been attributed mainly to its antioxidant and anti-inflammatory effects. This study investigated these effects on dextran sulphate sodium (DSS)-induced ulcerative colitis in rats. Sulfasalazine served as standard reference in this study. Kolaviron and sulfasalazine were separately co-administered orally at 200 mg/kg and 500 mg/kg, respectively, to dextran sulphate sodium-exposed rats for 5 days. The result indicated that kolaviron or sulfasalazine significantly prevented DSS-induced body weight loss as well as the incidence of diarrhoea and bleeding in DSS-exposed rats. Kolaviron suppressed the DSS-mediated increase in colonic nitric oxide concentration and myeloperoxidase activity and significantly prevented the increase in inflammatory mediators, interleukin-1β and tumour necrosis factor alpha, in the colon of DSS-treated rats. The significant depletion in colonic antioxidant status in rats exposed to DSS alone was evident by marked reduction in colonic catalase and glutathione S-transferase activities as well as glutathione content, leading to elevated hydrogen peroxide and lipid peroxidation levels. Histopathologically, DSS alone resulted in severe epithelial erosion, total absence of goblet cells, destruction of the crypts, necrotic and distorted glands, accompanied by marked cellular mononuclear cells infiltration. However, administration of kolaviron and sulfasalazine ameliorated DSS-induced colitis by increasing the antioxidant status decreased hydrogen peroxide and lipid peroxidation levels and attenuated the adverse effect of DSS on colon architecture. In conclusion, the anti-colitis effect of kolaviron is related to its intrinsic anti-inflammatory and anti-oxidative properties.

Nitric oxide suppresses NLRP3 inflammasome activation and protects against LPS-induced septic shock

Inflammasomes are multi-protein complexes that trigger the activation of caspase-1 and the maturation of interleukin-1β (IL-1β), yet the regulation of these complexes remains poorly characterized. Here we show that nitric oxide (NO) inhibited the NLRP3-mediated ASC pyroptosome formation, caspase-1 activation and IL-1β secretion in myeloid cells from both mice and humans. Meanwhile, endogenous NO derived from iNOS (inducible form of NO synthase) also negatively regulated NLRP3 inflammasome activation. Depletion of iNOS resulted in increased accumulation of dysfunctional mitochondria in response to LPS and ATP, which was responsible for the increased IL-1β production and caspase-1 activation. iNOS deficiency or pharmacological inhibition of NO production enhanced NLRP3-dependent cytokine production in vivo, thus increasing mortality from LPS-induced sepsis in mice, which was prevented by NLRP3 deficiency. Our results thus identify NO as a critical negative regulator of the NLRP3 inflammasome via the stabilization of mitochondria. This study has important implications for the design of new strategies to control NLRP3-related diseases.

A salmon peptide diet alleviates experimental colitis as compared with fish oil

Fish oil (FO) has been shown to have anti-inflammatory properties in animal models of inflammatory bowel disease, but how fish peptides (FP) influence intestinal inflammation has been less studied. Male Wistar rats, divided into five groups, were included in a 4-week dietary intervention study. Of the groups, four were exposed in the fourth week to 5 % dextran sulfate sodium (DSS) to induce colitis, while one group was unexposed. The diets were: (1) control, (2) control + DSS, (3) FO (5 %) + DSS, (4) FP (3·5 %) + DSS, (5) FO + FP + DSS. Following DSS intake, weight and disease activity index (DAI) were assessed, and histological combined score (HCS), selected colonic PG, cytokines, oxidative damage markers and mRNA levels were measured. FP reduced HCS, tended to lower DAI (P = 0·07) and reduced keratinocyte chemoattractant/growth-regulated oncogene levels, as compared with the FO diet. FP also reduced mRNA levels of Il-6 and Cxcl1, although not significantly. FO intake increased the DAI as compared with DSS alone. PGE3 levels increased after the FO diet, and even more following FO + FP intake. The FP diet seems to have a protective effect in DSS-induced colitis as compared with FO. A number of beneficial, but non-significant, changes also occurred after FP v. DSS. A combined FO + FP diet may influence PG synthesis, as PGE3 levels were higher after the combined diet than after FO alone.

Monotropein isolated from the roots of Morinda officinalis ameliorates proinflammatory mediators in RAW 264.7 macrophages and dextran sulfate sodium (DSS)-induced colitis via NF-κB inactivation

We previously demonstrated that monotropein isolated from the roots of Morinda officinalis (Rubiaceae) has anti-inflammatory effects in vivo. In the present study, we investigated the molecular mechanisms underlying the anti-inflammatory effects of monotropein in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages and dextran sulfate sodium (DSS)-induced colitis mouse model. Monotropein was found to inhibit the expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) mRNA in LPS-induced RAW 264.7 macrophages. Treatment with monotropein decreased the DNA binding activity of nuclear factor-κB (NF-κB). Consistent with these findings, monotropein also suppressed phosphorylation and degradation of inhibitory κB-α (IκB-α), and consequently the translocations of NF-κB. In the DSS-induced colitis model, monotropein reduced disease activity index (DAI), myeloperoxidase (MPO) activity, and inflammation-related protein expressions by suppressing NF-κB activation in colon mucosa. Taken together, these findings suggest that the anti-inflammatory effects of monotropein are mainly related to the inhibition of the expressions of inflammatory mediators via NF-κB inactivation, and support its possible therapeutic role in colitis.

Assessment of fractionated exhaled nitric oxide as a biomarker for the treatment of eosinophilic esophagitis

Diagnosis of eosinophilic esophagitis (EoE) and determination of response to therapy is based on histological assessment of the esophagus, which requires upper endoscopy. In children, in whom a dietary approach is commonly used, multiple endoscopies are needed, because foods are eliminated and then gradually reintroduced. Ideally, noninvasive methods could supplement or replace upper endoscopy to facilitate management. Fractionated exhaled nitric oxide (FeNO) has been proposed as a useful measure for monitoring disease activity in studies of patients with eosinophil-predominant asthma and in other atopic disorders. Thus, we evaluated whether FeNO levels could be a useful biomarker to assess the response to therapy in EoE patients. This study was designed to determine whether there is a change in FeNO levels during treatment with topical corticosteroids and whether changes correlated with clinical response. This was a prospective, multicenter study that enrolled nonasthmatic patients with established EoE. FeNO levels and symptom scores were measured at baseline, biweekly during 6-week swallowed fluticasone treatment, and 4 weeks posttreatment. Twelve patients completed the trial. We found a statistically significant difference between median pre- and posttreatment FeNO levels [20.3 ppb (16.0 -29.0 ppb) vs 17.6 ppb (11.7 -27.3 ppb), [corrected] p=0.009]. However, neither the pretreatment FeNO level, a change of FeNO level after 2 weeks of treatment, nor the FeNO level at the end of treatment confidently predicted a clinical or histological response. Although our findings suggest nitric oxide possibly has a physiological role in EoE, our observations do not support a role of FeNo determination for management of EoE.

Review of natural products actions on cytokines in inflammatory bowel disease

The purpose of this review is to provide an overview of the effects that natural products have on inflammatory bowel disease (IBD) and to provide insight into the relationship between these natural products and cytokines modulation. More than 100 studies from the past 10 years were reviewed herein on the therapeutic approaches for treating IBD. The natural products having anti-IBD actions included phytochemicals, antioxidants, microorganisms, dietary fibers, and lipids. The literature revealed that many of these natural products exert anti-IBD activity by altering cytokine production. Specifically, phytochemicals such as polyphenols or flavonoids are the most abundant, naturally occurring anti-IBD substances. The anti-IBD effects of lipids were primarily related to the n-3 polyunsaturated fatty acids. The anti-IBD effects of phytochemicals were associated with modulating the levels of tumor necrosis factor α (TNF-α), interleukin (IL)-1, IL-6, inducible nitric oxide synthase, and myeloperoxide. The anti-IBD effects of dietary fiber were mainly mediated via peroxisome proliferator-activated receptor-γ, TNF-α, nitric oxide, and IL-2, whereas the anti-IBD effects of lactic acid bacteria were reported to influence interferon-γ, IL-6, IL-12, TNF-α, and nuclear factor-κ light-chain enhancer of activated B cells. These results suggest that the anti-IBD effects exhibited by natural products are mainly caused by their ability to modulate cytokine production. However, the exact mechanism of action of natural products for IBD therapy is still unclear. Thus, future research is needed to examine the effect of these natural products on IBD and to determine which factors are most strongly correlated with reducing IBD or controlling the symptoms of IBD.

Orally administered aqueous extract of Inonotus obliquus ameliorates acute inflammation in dextran sulfate sodium (DSS)-induced colitis in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Chaga mushroom (Inonotus obliquus) has been used in folk medicine to treat several disorders through its various biological functions. I. obliquus is claimed to produce general immune-potentiating and strengthening, antiinflammatory, and antitumor properties, but its effects on intestinal inflammation (ulcerative colitis) are clearly not understood.

AIM OF THE STUDY

To determine the effects and mode of action of an aqueous extract of I. obliquus (IOAE) on experimental colitis in mice induced by dextran sulfate sodium (DSS).

MATERIALS AND METHODS

Female 5-week-C57BL/6 mice were randomized into groups differing in treatment conditions (prevention and treatment) and doses of IOAE (50 and 100mg/kg body weight). Mice were exposed to DSS (2%) in their drinking water over 7 day to induce acute intestinal inflammation. In colon tissues, we evaluated histological changes by hematoxylin and eosin staining, levels of iNOS by immuno-histochemical staining, and neutrophil influx by myeloperoxidase assay. mRNA expression of pro-inflammatory mediators TNF-α, IL-1β, IL-6, and IFN-γ was determined by RT-PCR.

RESULTS

Histological examinations indicated that IOAE suppressed edema, mucosal damage, and the loss of crypts induced by DSS. IOAE markedly attenuated DSS-induced iNOS levels and myeloperoxidase accumulation in colon tissues, demonstrating its suppressive effect on infiltration of immune cells. In addition, IOAE significantly inhibited mRNA expression of pro-inflammatory cytokines induced by DSS in colon tissues.

CONCLUSION

Our results suggest anti-inflammatory effect of IOAE at colorectal sites due to down-regulation of the expression of inflammatory mediators. Suppression of TNF-α and iNOS together with IL-1β by IOAE denotes that it might be a useful supplement in the setting of inflammatory bowel disease.

Genes differentially regulated by NKX2-3 in B cells between ulcerative colitis and Crohn's disease patients and possible involvement of EGR1

Ulcerative colitis (UC) and Crohn's disease (CD) are two related yet different forms of chronic intestinal inflammation. We investigated the genes regulated by NKX2-3 in B cells from a UC patient by cDNA microarray and compared the results to those genes regulated by NKX2-3 in B cells from a CD patient. Genes regulated by NKX2-3 in B cells from UC were mainly involved in cell growth, inflammation, and immune response. Among the genes regulated by NKX2-3 in both UC and CD, expression of 145 genes was similarly altered and 34 genes was differentially affected by NKX2-3 knockdown. EGR1 was up-regulated in NKX2-3 knockdown B cells from UC while down-regulated in NKX2-3 knockdown B cells from CD. mRNA expressions of NKX2-3 and EGR1 were increased in diseased intestinal tissues from 19 CD patients. NKX2-3 may play different roles in UC and CD pathogenesis by differential regulation of EGR1.

Arvelexin inhibits colonic inflammation by suppression of NF-κB activation in dextran sulfate sodium-induced mice and TNF-α-induced colonic epithelial cells

Recently, we reported the anti-inflammatory effects of arvelexin isolated from Brassica rapa in macrophages. In the present study, the effects of arvelexin were investigated in a dextran sulfate sodium (DSS)-induced colitis mouse model and in a cellular model. In the DSS-induced colitis model, arvelexin significantly reduced the severity of colitis, as assessed by disease activity, colonic damage, neutrophil infiltration, and levels of colonic iNOS. Moreover, arvelexin inhibited the expressions of IL-8, IP-10, ICAM-1, and VCAM-1 in HT-29 colonic epithelial cells. Arvelexin also inhibited the TNF-α-induced adhesion of U937 monocytic cells to HT-29 cells. Furthermore, arvelexin reduced p65 NF-κB subunit translocation to the nucleus and IκBα degradation in the colonic tissues and in TNF-α-induced HT-29 cells. These results demonstrate that the ameliorative effects of arvelexin on colonic injury are mainly related to its ability to inhibit the inflammatory responses via NF-κB inactivation, and support its possible therapeutic role in colitis.

Molecular mechanisms of anti-inflammatory action of the flavonoid, tricin from Njavara rice (Oryza sativa L.) in human peripheral blood mononuclear cells: possible role in the inflammatory signaling

Flavonoids are a group of natural substances that are located in sources of vegetal origin and are able to regulate acute and chronic inflammatory responses. The anti-oxidant and anti-inflammatory effects corroborate with the preferential use of Njavara, a rice variety in indigenous medicine and the phytochemical investigations revealed the occurrence of a flavonoid, tricin at significantly higher levels compared to staple varieties. This study describes the new aspects of inflammatory suppression by the Njavara rice by evaluating the role of active constituent, tricin in the regulation of production of various pro-inflammatory markers by human peripheral blood mononuclear cells stimulated with lipopolysaccharide. Treatment with tricin resulted in significant down-regulation of LPS-elicited production of TNF-α, IL-6, PGE(2) and NO. Tricin was found to be a potential blocker of the expression of isoforms of nitric oxide synthase, cyclooxygenase and matrix metalloproteinases. Modulation of the cascade of molecular events in lipopolysaccharide signaling also includes inhibition of transcription factor NF-κB evidenced by the detection of enhanced p65 subunit in the nuclear extracts on tricin supplementation. The present study summarizes the role of the flavonoid, tricin in the modulation of the expression of different inflammatory mediators and revealed that the inhibitory effects on cell signaling pathways are responsible for its anti-inflammatory activity.

Effects of Feiyanning Decoction, a compound traditional Chinese medicine, on iNOS and COX-2 expressions induced by tumor necrosis factor-α in lung adenocarcinoma cell line

OBJECTIVE

To study the effect of Feiyanning Decoction (FYN), a compound traditional Chinese medicine, on expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) activated by tumor necrosis factor-α (TNF-α) in human lung adenocarcinoma epithelial cell line (A549).

METHODS

A549 cells were incubated with rat serum containing FYN for 24 h. Gene expressions of iNOS and COX-2 were determined by quantitative real-time polymerase chain reaction and Western blot. The iNOS-dependent luciferase reporter was transfected for 24 h and the cells were treated with the reagents for 24 h, then the transcriptional activity of iNOS promoter was detected by luciferase assay. The production of NO was determined by diaminofluorescein-2.

RESULTS

FYN significantly inhibited TNF-α-induced expression of iNOS and COX-2 compared with the control group in A549 cells (P<0.01, P<0.01). Also, FYN inhibited the transcriptional activity of the iNOS promoter and reduced NO production compared with the control group (P<0.01, P<0.01).

CONCLUSION

These results suggest that FYN inhibits iNOS and COX-2 activation induced by TNF-α, therefore, it is expected to develop a new strategy to treat lung cancer.

Ulcerative colitis impairs the acylethanolamide-based anti-inflammatory system reversal by 5-aminosalicylic acid and glucocorticoids

Studies in animal models and humans suggest anti-inflammatory roles on the N-acylethanolamide (NAE)-peroxisome proliferators activated receptor alpha (PPARα) system in inflammatory bowel diseases. However, the presence and function of NAE-PPARα signaling system in the ulcerative colitis (UC) of humans remain unknown as well as its response to active anti-inflammatory therapies such as 5-aminosalicylic acid (5-ASA) and glucocorticoids. Expression of PPARα receptor and PPARα ligands-biosynthetic (NAPE-PLD) and -degrading (FAAH and NAAA) enzymes were analyzed in untreated active and 5-ASA/glucocorticoids/immunomodulators-treated quiescent UC patients compared to healthy human colonic tissue by RT-PCR and immunohistochemical analyses. PPARα, NAAA, NAPE-PLD and FAAH showed differential distributions in the colonic epithelium, lamina propria, smooth muscle and enteric plexus. Gene expression analysis indicated a decrease of PPARα, PPARγ and NAAA, and an increase of FAAH and iNOS in the active colitis mucosa. Immunohistochemical expression in active colitis epithelium confirmed a PPARα decrease, but showed a sharp NAAA increase and a NAPE-PLD decrease, which were partially restored to control levels after treatment. We also characterized the immune cells of the UC mucosa infiltrate. We detected a decreased number of NAAA-positive and an increased number of FAAH-positive immune cells in active UC, which were partially restored to control levels after treatment. NAE-PPARα signaling system is impaired during active UC and 5-ASA/glucocorticoids treatment restored its normal expression. Since 5-ASA actions may work through PPARα and glucocorticoids through NAE-producing/degrading enzymes, the use of PPARα agonists or FAAH/NAAA blockers that increases endogenous PPARα ligands may yield similar therapeutics advantages.

L-arginine uptake by cationic amino acid transporter 2 is essential for colonic epithelial cell restitution

Restoration of the colonic epithelial barrier is an important response during colitis. L-arginine (L-Arg) is a semiessential amino acid that reduces murine colitis induced by Citrobacter rodentium. Cationic amino acid transporter (CAT) proteins increase L-Arg uptake into cells. L-Arg is utilized to produce nitric oxide (NO), by inducible NO synthase (iNOS), or L-ornithine (L-Orn) by arginase (Arg) enzymes. The latter is followed by generation of polyamines by ornithine decarboxylase (ODC) and L-proline (L-Pro) by ornithine aminotransferase (OAT). We show that L-Arg enhanced epithelial restitution in conditionally immortalized young adult mouse colon (YAMC) cells in a wound repair model, and in isolated mouse colonic epithelial cells (CECs), using a cell migration assay. Restitution was impaired by C. rodentium. Wounding induced CAT2, and inhibition of L-Arg uptake by the competitive inhibitor L-lysine (L-Lys) or by CAT2 shRNA, but not CAT1 shRNA, decreased restitution. Migration was impaired in CECs treated with L-Lys or from CAT2(-/-) mice. Wounding increased Arg1 expression, and inhibition of arginase with S-(2-boronoethyl)-L-cysteine (BEC) or Arg1 shRNA inhibited restitution in YAMC cells; cell migration in CECs was also impaired by BEC. Inhibition of ODC or iNOS did not alter restitution. L-Orn or L-Pro restored restitution in cells treated with BEC or Arg1 shRNA, whereas the polyamine putrescine had no benefit. Wounding increased OAT levels, OAT shRNA inhibited restitution, and L-Pro restored restitution in cells with OAT knockdown. Uptake of L-Arg, and its metabolism by Arg1 to L-Orn and conversion to L-Pro by OAT is essential for colonic epithelial wound repair.

Pharmacokinetic/pharmacodynamic modeling of methylprednisolone effects on iNOS mRNA expression and nitric oxide during LPS-induced inflammation in rats

PURPOSE

Increased expression of inducible nitric oxide synthase (iNOS) resulting in nitric oxide elevation represents an important component of inflammatory responses. We assess the effects of methylprednisolone (MPL) on these processes during endotoxin-induced acute inflammation and provide a mechanism-based model to quantitatively describe them.

METHODS

Male Lewis rats were dosed with lipopolysaccharide (50 μg/kg LPS) alone or with methylprednisolone (10 and 50 mg/kg) and sacrificed at different time points. Plasma MPL, lung iNOS mRNA expression, plasma nitric oxide (NO) and other physiological factors were measured. Sodium nitrate (750 μmole/kg) was given to a separate cohort of rats to assess NO disposition kinetics. PK-PD modeling was performed with ADAPT 5.

RESULTS

Disposition kinetics of plasma MPL and NO showed bi-exponential decline and were described by two-compartment models. LPS increased expression of iNOS mRNA in lung and increased plasma NO, while MPL dosing palliated this increase in a dose-dependent manner. These effects were well captured using tandem indirect response and precursor-pool models.

CONCLUSION

The model provides a quantitative assessment of the suppression of NO production by MPL and shows that the major effects are at the transcriptional level by reducing expression of iNOS mRNA.

L-arginine supplementation improves responses to injury and inflammation in dextran sulfate sodium colitis

Inflammatory bowel disease (IBD), consisting of Crohn's disease and ulcerative colitis (UC), results in substantial morbidity and is difficult to treat. New strategies for adjunct therapies are needed. One candidate is the semi-essential amino acid, L-arginine (L-Arg), a complementary medicine purported to be an enhancer of immunity and vitality in the lay media. Using dextran sulfate sodium (DSS) as a murine colonic injury and repair model with similarities to human UC, we assessed the effect of L-Arg, as DSS induced increases in colonic expression of the y(+) cationic amino acid transporter 2 (CAT2) and L-Arg uptake. L-Arg supplementation improved the clinical parameters of survival, body weight loss, and colon weight, and reduced colonic permeability and the number of myeloperoxidase-positive neutrophils in DSS colitis. Luminex-based multi-analyte profiling demonstrated that there was a marked reduction in proinflammatory cytokine and chemokine expression with L-Arg treatment. Genomic analysis by microarray demonstrated that DSS-treated mice supplemented with L-Arg clustered more closely with mice not exposed to DSS than to those receiving DSS alone, and revealed that multiple genes that were upregulated or downregulated with DSS alone exhibited normalization of expression with L-Arg supplementation. Additionally, L-Arg treatment of mice with DSS colitis resulted in increased ex vivo migration of colonic epithelial cells, suggestive of increased capacity for wound repair. Because CAT2 induction was sustained during L-Arg treatment and inducible nitric oxide (NO) synthase (iNOS) requires uptake of L-Arg for generation of NO, we tested the effect of L-Arg in iNOS(-/-) mice and found that its benefits in DSS colitis were eliminated. These preclinical studies indicate that L-Arg supplementation could be a potential therapy for IBD, and that one mechanism of action may be functional enhancement of iNOS activity.

Pegylated arginine deiminase downregulates colitis in murine models

Arginine deiminase (ADI), an arginine-metabolizing enzyme involved in cell signaling, is dysregulated in multiple inflammatory diseases and cancers. We hypothesized that pegylated ADI (ADI-PEG) provide protection against colitis. Methods. Dextran sodium sulfate colitis was induced in IL-10-deficient and BALB/c (WT) mice. ADI-PEG was administered i.p., and inflammatory mediators and pathology were evaluated. Results. Acute colitis in mice was manifested by increases in inflammatory biomarkers, such as serum amyloid A (SAA, P < 0.001), IL-12 p40, and disease index (3-Fold). In contrast, ADI-PEG significantly decreased clinical disease index, SAA levels, and inflammatory cytokines in blood as well as in colonic explants. Animals developed moderate (2.2 ± 0.3 WT) to severe (3.6 ± 0.5 IL-10 deficient) colonic pathology; and ADI-PEG treatment significantly improved the severity of colitis (P < 0.05). Marked infiltration of CD68⁺ macrophages and iNOS expression were detected in colonic submucosa in colitic animals but not detected in ADI-PEG-treated animals. Conclusion. ADI-PEG attenuated inflammatory responses by suppression of macrophage infiltration and iNOS expression in colitic animals. ADI-PEG can serve as a potential therapeutic value in IBD.

Preventive and therapeutic euphol treatment attenuates experimental colitis in mice

BACKGROUND

The tetracyclic triterpene euphol is the main constituent found in the sap of Euphorbia tirucalli. This plant is widely known in Brazilian traditional medicine for its use in the treatment of several kinds of cancer, including leukaemia, prostate and breast cancers. Here, we investigated the effect of euphol on experimental models of colitis and the underlying mechanisms involved in its action.

METHODOLOGY/PRINCIPAL FINDINGS

Colitis was induced in mice either with dextran sulfate sodium (DSS) or with 2,4,6-trinitrobenzene sulfonic acid (TNBS), and the effect of euphol (3, 10 and 30 mg/kg) on colonic injury was assessed. Pro-inflammatory mediators and cytokines were measured by immunohistochemistry, enzyme-Linked immunoabsorbent assay (ELISA), real time-polymerase chain reaction (RT-PCR) and flow cytometry. Preventive and therapeutic oral administration of euphol attenuated both DSS- and TNBS-induced acute colitis as observed by a significant reduction of the disease activity index (DAI), histological/microscopic damage score and myeloperoxidase (MPO) activity in colonic tissue. Likewise, euphol treatment also inhibited colon tissue levels and expression of IL-1β, CXCL1/KC, MCP-1, MIP-2, TNF-α and IL-6, while reducing NOS2, VEGF and Ki67 expression in colonic tissue. This action seems to be likely associated with inhibition of activation of nuclear factor-κB (NF-κB). In addition, euphol decreased LPS-induced MCP-1, TNF-α, IL-6 and IFN-γ, but increased IL-10 secretion from bone marrow-derived macrophages in vitro. Of note, euphol, at the same schedule of treatment, markedly inhibited both selectin (P- and E-selectin) and integrin (ICAM-1, VCAM-1 and LFA-1) expression in colonic tissue.

CONCLUSIONS/SIGNIFICANCE

Together, these results clearly demonstrated that orally-administered euphol, both preventive or therapeutic treatment were effective in reducing the severity of colitis in two models of chemically-induced mouse colitis and suggest this plant-derived compound might be a potential molecule in the management of inflammatory bowel diseases.

Heme oxygenase-1 system and gastrointestinal inflammation: A short review

Heme oxygenase-1 (HO-1) system catalyzes heme to biologically active products: carbon monoxide, biliverdin/bilirubin and free iron. It is involved in maintaining cellular homeostasis and many physiological and pathophysiological processes. A growing body of evidence indicates that HO-1 activation may play an important protective role in acute and chronic inflammation of gastrointestinal tract. This review focuses on the current understanding of the physiological significance of HO-1 induction and its possible roles in the gastrointestinal inflammation studied to date. The ability to upregulate HO-1 by pharmacological means or using gene therapy may offer therapeutic strategies for gastrointestinal inflammation in the future.

Decrease of guanylyl cyclase β1 subunit and nitric oxide (NO)-induced relaxation in mouse rectum with colitis and its reproduction on long-term NO treatment

Nitric oxide (NO) influences motility in the colon in patients with ulcerative colitis, but the exact mechanism involved remains unknown. Colitis was induced in mice by the oral administration of 2.5% dextran sodium sulfate (DSS), and the motility in longitudinal preparations from rectum and distal colon and expression of β1 subunit of soluble guanylyl cyclase (sGCβ1) were analyzed. Electrical stimulation (ES) caused a transient relaxation via the NO pathway in both rectum and colon from control mice. Stimulation with sodium nitroprusside (SNP) caused relaxation in the two regions, and the half-time (T (1/2)) of the maximal relaxation induced by 100 μM SNP was 8.1 ± 1.0 s in rectum. DSS treatment (1) abolished the ES-induced relaxation, but not dibutyryl cyclic GMP-induced response, in both regions, (2) decreased the maximal response to SNP accompanied by a loss of immunoreactive sGCβ1 protein in rectum, but did not affect the amplitude of the relaxant response or the protein in distal colon, and (3) caused an increase in the T (1/2) value in response to SNP in both regions. Pretreatment of both preparations from control mice with 600 μM SNP for 30 min decreased both ES- and SNP-induced relaxation, SNP-induced cyclic GMP formation, and immunoreactive sGCβ1 levels. NO-mediated relaxation was impaired by a dysfunctional sGC with and without a loss of immunoreactivity to sGCβ1 in rectum and colon from DSS-treated mice, respectively. Long-term exposure of the tissues with an excess amount of NO changes the sGC-mediated relaxation.

Dysfunction of neurogenic VIP-mediated relaxation in mouse distal colon with dextran sulfate sodium-induced colitis

Vasoactive intestinal peptide (VIP) regulates various functions including motility and immune homeostasis in colon. The VIP system including its receptors has been established to control the development of ulcerative colitis, but the functional changes of the system-regulated motility in colon with ulcerative colitis are not well understood. In this study, we investigated VIP-related contractile responses in distal colon from mice with dextran sulfate sodium (DSS)-induced acute colitis. Electrical stimulation (ES) under our conditions caused relaxation during ES and contraction after withdrawal of ES in a tetrodotoxin-sensitive manner. Pharmacological analyses showed two phases of ES-induced relaxation: a transient neuronal nitric oxide (NO) synthase-dependent phase (I), and a continued VIP receptor-mediated phase (II). Inhibition of VIP receptors and protein kinase A decreased both phases. In colon from DSS-treated mice, ES-induced phase II (also phase I) and VIP-induced, but not cyclic AMP analog-induced, relaxation were decreased. Stimulation with VIP significantly increased cyclic AMP formation in colon preparations from control but not DSS-treated mice. In colon from DSS-treated mice, the basal cyclic AMP level was markedly greater without changes in the level of VIP receptor VPAC(2). Isoprenaline- and forskolin-induced relaxation and cyclic AMP formation were not changed by DSS treatment. These findings suggest that dysfunction of VIP receptors in muscles, in addition to loss of the neuronal VIP and NO pathways, are involved in abnormal motility in mouse colon with DSS-induced colitis.

Anti-inflammatory effects of methanol extract of Patrinia scabiosaefolia in mice with ulcerative colitis

ETHNOPHARMACOLOGICAL RELEVANCE

Patrinia scabiosaefolia Fisch is used in folk medicines to treat intestinal abscesses, acute appendicitis, and dysentery in Asia. Although recent reports indicate that Patrinia scabiosaefolia has sedative and anti-tumor effects, its effects on ulcerative colitis have not been previously explored.

AIM OF THE STUDY

To determine the effects and the mode of action of the methanol extract of the roots of Patrinia scabiosaefolia (PME) on a model of colitis in mice induced by dextran sulfate sodium (DSS).

MATERIALS AND METHODS

We induced colitis using DSS in 5-week-ICR mice over 7 days and estimated disease activity index (DAI), which took into account body weight, stool consistency, gross bleeding, and tissue myeloperoxidase (MPO) accumulation. Colon lengths and spleen weights were measured. Histological changes were observed by H&E staining. Pro-inflammatory mediators, namely, nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), were determined using Griess assays, immunoassays, and by quantitative real-time reverse-transcriptase polymerase chain reaction (qRT-PCR), respectively.

RESULTS

PME significantly attenuated DSS-induced DAI scores and tissue MPO accumulation, which implied that it suppressed weight loss, diarrhea, gross bleeding, and the infiltrations of immune cells. PME administration also effectively and dose-dependently prevented shortening of colon length and enlargement of spleen size. Histological examinations indicated that PME suppressed edema, mucosal damage, and the loss of crypts induced by DSS. Furthermore, PME inhibited the abnormal secretions and mRNA expressions of pro-inflammatory cytokines, such as, TNF-α, IL-1β, and IL-6.

CONCLUSION

These results suggest that PME has an anti-inflammatory effect at colorectal sites that is due to the down-regulations of the productions and expressions of inflammatory mediators, and that it may have therapeutic value in the setting of inflammatory bowel disease (IBD).

Chronic lithium administration ameliorates 2,4,6-trinitrobenzene sulfonic acid-induced colitis in rats; potential role for adenosine triphosphate sensitive potassium channels

BACKGROUND AND AIM

Inflammatory bowel disease (IBD) is a multi-factorial disease with an unknown etiology characterized by oxidative stress, leukocyte infiltration and a rise in inflammatory cytokines. This study was conducted to investigate lithium in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced chronic model of experimental IBD, and the contribution of potassium channels as a possible underlying mechanism.

METHODS

Experimental IBD was induced in rats by a single colonic administration of 10 mg of TNBS. Lithium, Glibenclamide (a potassium channel blocker), Lithium + Glibenclamide, Cromakalim or Lithium+Glibenclamide+ Cromakalim were given twice daily for 7 successive days. At the end of the experiment, macroscopic and histopathologic scores, colonic malondialdehyde (MDA), tumor necrosis factor-α (TNF-α) level, and myeloperoxidase (MPO) activity as well as plasma lithium level were assessed.

RESULTS

Both macroscopic and histological features of colonic injury were markedly ameliorated by lithium. Likewise, the elevated amounts of MPO and MDA were diminished as well as those of TNF-α (P < 0.05). Glibenclamide reversed the effect of lithium on these markers, Addition of cromakalim abrogated the effects mediated by glibenclamide and markedly decreased MPO activity, MDA level and TNF-α content (P < 0.0.05). Macroscopic and microscopic scores and biochemical markers were significantly decreased in Cromakalim-treated animals. No significant difference was observed between TNBS and Glibenclamide groups.

CONCLUSION

Lithium exerts prominent anti-inflammatory effects on TNBS-induced colitis in rats. Potassium channels contribute to these beneficial properties.

Role of neuronal nitric oxide synthase in colonic distension-induced hyperalgesia in distal colon of neonatal maternal separated male rats

BACKGROUND

Nitric oxide (NO) is implicated in the pathogenesis of irritable bowel syndrome (IBS) but the underlying mechanism is unclear. Thus, the aim of the present study is to examine the role of NO synthase (NOS) expression in the distal colon of neonatal maternal separation (NMS) model rats employed in IBS studies.

METHODS

Male neonates of Sprague-Dawley rats were randomly assigned into NMS and normal control (N) groups. Rats of NMS group were subjected to 3 h daily maternal separation on postnatal day 2-21. Rats were administrated non-selective NOS inhibitor l-NAME (100 mg kg(-1) ), selective neuronal NOS (nNOS) inhibitor 7-NINA (10mgkg(-1) ), selective inducible NOS (iNOS) inhibitor, endothelial NOS (eNOS) inhibitor (10mgkg(-1) ) or Vehicle (Veh; distilled water) intraperitoneally 1h prior to the experiment for the test and control groups, respectively.

KEY RESULTS

The amount of NO was significantly higher in the NMS Veh rats compared with unseparated N rats. Western-blotting and real-time quantitative PCR studies showed that protein and mRNA expression of nNOS were higher in the NMS group than that in the N rats; whereas no significant change in iNOS and eNOS was found in either groups. Neonatal maternal separation Veh rats showed low pain threshold and increased electromyogram (EMG) activity in response to colonic distension stimuli. l-NAME and 7-Nitroindazole monosodium salt (7-NINA) increased pain threshold pressure and attenuated EMG activity in the NMS rats. In addition, l-NAME and 7-NINA substantially reduced oxidative marker malondialdehyde level in NMS rats.

CONCLUSIONS & INFERENCES

Neonatal maternal separation increased the NO generation by nNOS upregulation that interact with reactive oxygen species contributing to the visceral hypersensitivity in IBS.

Nitric oxide regulation of colonic epithelial ion transport: a novel role for enteric glia in the myenteric plexus

Enteric glia are increasingly recognized as important in the regulation of a variety of gastrointestinal functions.Here we tested the hypothesis that nicotinic signalling in the myenteric plexus results in the release of nitric oxide (NO) from neurons and enteric glia to modulate epithelial ion transport. Ion transport was assessed using full-thickness or muscle-stripped segments of mouse colon mounted in Ussing chambers. The cell-permeant NO-sensitive dye DAR-4M AM and amperometry were utilized to identify the cellular sites of NO production within the myenteric plexus and the contributions from specific NOS isoforms. Nicotinic receptors were localized using immunohistochemistry. Nicotinic cholinergic stimulation of colonic segments resulted in NO-dependent changes in epithelial active electrogenic ion transport that were TTX sensitive and significantly altered in the absence of the myenteric plexus. Nicotinic stimulation of the myenteric plexus resulted in NO production and release from neurons and enteric glia, which was completely blocked in the presence of nitric oxide synthase (NOS) I and NOS II inhibitors. Using the NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), neuronal and enteric glial components of NO production were demonstrated. Nicotinic receptors were identified on enteric neurons, which express NOS I, and enteric glia, which express NOS II. These data identify a unique pathway in the mouse colon whereby nicotinic cholinergic signalling in myenteric ganglia mobilizes NO from NOS II in enteric glia, which in coordinated activity with neurons in the myenteric plexus modulates epithelial ion transport, a key component of homeostasis and innate immunity.

Iron regulatory protein 1 outcompetes iron regulatory protein 2 in regulating cellular iron homeostasis in response to nitric oxide

In mammals, iron regulatory proteins (IRPs) 1 and 2 posttranscriptionally regulate expression of genes involved in iron metabolism, including transferrin receptor 1, the ferritin (Ft) H and L subunits, and ferroportin by binding mRNA motifs called iron responsive elements (IREs). IRP1 is a bifunctional protein that mostly exists in a non-IRE-binding, [4Fe-4S] cluster aconitase form, whereas IRP2, which does not assemble an Fe-S cluster, spontaneously binds IREs. Although both IRPs fulfill a trans-regulatory function, only mice lacking IRP2 misregulate iron metabolism. NO stimulates the IRE-binding activity of IRP1 by targeting its Fe-S cluster. IRP2 has also been reported to sense NO, but the intrinsic function of IRP1 and IRP2 in NO-mediated regulation of cellular iron metabolism is controversial. In this study, we exposed bone marrow macrophages from Irp1(-/-) and Irp2(-/-) mice to NO and showed that the generated apo-IRP1 was entirely responsible for the posttranscriptional regulation of transferrin receptor 1, H-Ft, L-Ft, and ferroportin. The powerful action of NO on IRP1 also remedies the defects of iron storage found in IRP2-null bone marrow macrophages by efficiently reducing Ft overexpression. We also found that NO-dependent IRP1 activation, resulting in increased iron uptake and reduced iron sequestration and export, maintains enough intracellular iron to fuel the Fe-S cluster biosynthetic pathway for efficient restoration of the citric acid cycle aconitase in mitochondria. Thus, IRP1 is the dominant sensor and transducer of NO for posttranscriptional regulation of iron metabolism and participates in Fe-S cluster repair after exposure to NO.

Protective effects of Kurozu and Kurozu Moromimatsu on dextran sulfate sodium-induced experimental colitis

BACKGROUND

Kurozu, a traditional Japanese black vinegar made from unpolished rice, and Kurozu Moromimatsu (Kurozu-M), its sediment, are both consumed in Japan as health foods or supplements. However, it is not known whether they have anti-colitis activity.

AIMS

We examined the protective effects of Kurozu and Kurozu-M in an animal model of dextran sulfate sodium (DSS)-induced colitis.

METHODS

DSS-induced colitis was induced in C57 black 6 mice by orally administering 3.5% DSS solution for 12 days. The control group received basal CE-2 diet (n = 10), the Kurozu group received CE-2 containing Kurozu (n = 10), the Kurozu-M group received CE-2 containing Kurozu-M (n = 10), and the acetic acid group received CE-2 containing acetic acid (n = 10), starting a week before DSS administration. Changes of body weight and bloody stool frequency were monitored. At 12 days after DSS administration, mice were killed for pathological examination and measurement of nitrotyrosine levels in rectal tissues.

RESULTS

Kurozu significantly inhibited body weight loss during 6-12 days after DSS administration and reduced bloody stool frequency during 2-12 days, and also significantly decreased nitrotyrosine levels at 12 days, compared to the control group. Kurozu-M significantly inhibited body weight loss during 6-8 days after DSS administration and reduced bloody stool frequency during 2-12 days, but tissue nitrotyrosine level was not significantly different from the control. Acetic acid had no ameliorating effect on DSS-induced colitis compared to the control group.

CONCLUSIONS

Kurozu and Kurozu-M have protective effects against DSS-induced colitis. Kurozu has anti-oxidative and anti-nitration activity.

Protective Effect of Anthocyanins Extract from Blueberry on TNBS-Induced IBD Model of Mice

This study was carried out to evaluate the protective effect of anthocyanins extract of blueberry on trinitrobenzene sulfonic acid (TNBS)-induced inflammatory bowel disease (IBD) model of mice. The study employed female C57BL/6 mice (n = 50), and colitis was induced by intracolonic injection of 0.5 mg of TNBS dissolved in 50% ethanol-phosphate buffered solution. The mice were divided into five groups (n = 10): vehicle, TNBS control and anthocyanins groups that received different doses of anthocyanins extract (10, 20 and 40 mg kg(-1)) daily for 6 days. Both increase in body weight and diarrhea symptoms were monitored each day. After 6 days, the animals were killed, and the following parameters were assessed: colon length, morphological score, histological score and biochemical assay (NO, myeloperoxidase (MPO), interleukin (IL)-12, IL-10, tumor necrosis factor (TNF)-α and interferon (IFN)-γ). The results showed that the anthocyanins extract of blueberry rendered strong protection against TNBS-induced colonic damage at a dosage of 40 mg kg(-1). When compared with the control, anthocyanins extract significantly prevented loss of body weight and ameliorated the scores of diarrhea, morphology and histology. Treatment with anthocyanins extract restored IL-10 excretion, as well as caused reduction in the levels of NO, MPO, IL-12, TNF-α and IFN-γ. Our research revealed the protective effect of anthocyanins extract from blueberry on TNBS-induced experimental colitis in mice, as well as examined whether high levels of dietary blueberries would lower the risk or have protective effects on human IBD, which may require further investigation.

Cordyceps militaris extract suppresses dextran sodium sulfate-induced acute colitis in mice and production of inflammatory mediators from macrophages and mast cells

ETHNOPHARMACOLOGICAL RELEVANCE

Cordyceps militaris is a well-known medicinal mushroom used for treatment of asthma, and other bronchial and lung inflammatory diseases.

AIM OF THE STUDY

To investigate the anti-inflammatory effects and mechanism of Cordyceps militaris extract on a murine model of acute colitis.

MATERIALS AND METHODS

We induced colitis using DSS for 1 week. The disease activity index (DAI) took into account body weight loss, diarrhea, and bleeding. Colon length and crypt length were measured using a microscope. Structural changes of the colon were observed by H&E staining. NO, iNOS, and TNF-α were determined using the Griess assay. iNOS protein was determined using western blotting and quantitative reverse-transcriptase polymerase chain reaction, respectively. Degranulated mast cells in colon tissue were stained using toluidine blue. The degree of degranulated RBL-2H3 cells was measured by the β-hexosaminidase assay.

RESULTS

Cordyceps militaris extract significantly attenuated DSS-induced DAI scores (e.g., body weight loss, diarrhea, gross bleeding). Cordyceps militaris extract also effectively prevented shortening of colon length and crypt length. Histological analysis indicated that Cordyceps militaris extract suppressed epithelial damage, loss of goblet cells, loss of crypts, and infiltration of inflammatory cells induced by DSS. In addition, Cordyceps militaris extract inhibited iNOS and TNF-α mRNA expression in colon tissue of DSS-induced colitis and in LPS-stimulated RAW264.7 cells. Cordyceps militaris extract suppressed degranulation of mast cells in the colon of mice with DSS-induced colitis and in antigen-stimulated mast cells.

CONCLUSION

These results suggest that Cordyceps militaris extract has anti-inflammatory activity in DSS-induced acute colitis by down-regulating production and expression of inflammatory mediators. These findings suggest that Cordyceps militaris extract might be applied as an agent for prevention or treatment of inflammatory bowel diseases (IBDs).

The apolipoprotein E-mimetic peptide COG112 inhibits NF-kappaB signaling, proinflammatory cytokine expression, and disease activity in murine models of colitis

Inflammatory bowel disease (IBD), consisting of Crohn's disease and ulcerative colitis, is a source of substantial morbidity and remains difficult to treat. New strategies for beneficial anti-inflammatory therapies would be highly desirable. Apolipoprotein (apo) E has immunomodulatory effects and synthetically derived apoE-mimetic peptides are beneficial in models of sepsis and neuroinflammation. We have reported that the antennapedia-linked apoE-mimetic peptide COG112 inhibits the inflammatory response to the colitis-inducing pathogen Citrobacter rodentium in vitro by inhibiting NF-κB activation. We now determined the effect of COG112 in mouse models of colitis. Using C. rodentium as an infection model, and dextran sulfate sodium (DSS) as an injury model, mice were treated with COG112 by intraperitoneal injection. With C. rodentium, COG112 improved the clinical parameters of survival, body weight, colon weight, and histologic injury. With DSS, COG112 ameliorated the loss of body weight, reduction in colon length, and histologic injury, whether administered concurrently with induction of colitis, during induction plus recovery, or only during the recovery phase of disease. In both colitis models, COG112 inhibited colon tissue inducible nitric-oxide synthase (iNOS), KC, TNF-α, IFN-γ, and IL-17 mRNA expression, and reduced nuclear translocation of NF-κB, as determined by immunoblot and immunofluorescence confocal microscopy. IκB kinase (IKK) activity was also reduced, which is necessary for activation of the canonical NF-κB pathway. Isolated colonic epithelial cells exhibited marked attenuation of expression of iNOS and the CXC chemokines KC and MIP-2. These studies indicate that apoE-mimetic peptides such as COG112 are novel potential therapies for IBD.

Embelin ameliorates dextran sodium sulfate-induced colitis in mice

Embelin has been used to treat fever, inflammatory diseases, and a variety of gastrointestinal ailments for thousands of years. Although reports indicate that embelin has anti-inflammatory and anti-tumor effects, its effects on ulcerative colitis have not been previously explored. The purpose of the present work was to evaluate the anti-inflammatory effect of embelin on dextran sulfate sodium (DSS)-induced colitis. Experimental colitis was induced in BALB/c mice by dissolving 5% DSS in their drinking water for 7days. Embelin (10, 30 or 50mg/kg body weight) was administrated daily per oral route for 7days. Embelin significantly attenuated DSS-induced DAI scores and tissue MPO accumulation, which implied that it suppressed weight loss, diarrhea, gross bleeding, and the infiltrations of immune cells. Embelin administration also effectively and dose-dependently prevented shortening of colon length and enlargement of spleen size. Histological examinations indicated that embelin suppressed edema, mucosal damage, and the loss of crypts induced by DSS. Furthermore, embelin inhibited the abnormal secretions and mRNA expressions of pro-inflammatory cytokines, such as, TNF-α, IL-1β, and IL-6. These results suggest that embelin has an anti-inflammatory effect at colorectal sites that is due to the down-regulations of the productions and expressions of inflammatory mediators, and that it may have therapeutic value in the setting of inflammatory bowel disease (IBD).

Increased expression and cellular localization of spermine oxidase in ulcerative colitis and relationship to disease activity

BACKGROUND

Polyamines are important in cell growth and wound repair, but have also been implicated in inflammation-induced carcinogenesis. Polyamine metabolism includes back-conversion of spermine to spermidine by the enzyme spermine oxidase (SMO), which produces hydrogen peroxide that causes oxidative stress. In ulcerative colitis (UC), levels of spermine are decreased compared to spermidine. Therefore, we sought to determine if SMO is involved in UC.

METHODS

Colon biopsies and clinical information from subjects undergoing colonoscopy for evaluation of UC or colorectal cancer screening were utilized from 16 normal controls and 53 UC cases. Histopathologic disease severity was graded and the Mayo Disease Activity Index (DAI) and endoscopy subscore assessed. SMO mRNA expression was measured in frozen biopsies by TaqMan-based real-time polymerase chain reaction (PCR). Formalin-fixed tissues were used for SMO immunohistochemistry.

RESULTS

There was a 3.1-fold upregulation of SMO mRNA levels in UC patients compared to controls (P = 0.044), and a 3.7-fold increase in involved left colon versus paired uninvolved right colon (P < 0.001). With worsening histologic injury in UC there was a progressive increase in SMO staining of mononuclear inflammatory cells. There was a similar increase in SMO staining with worsening endoscopic disease severity and strong correlation with the DAI (r = 0.653, P < 0.001). Inflammatory cell SMO staining was increased in involved left colon versus uninvolved right colon.

CONCLUSIONS

SMO expression is upregulated in UC tissues, deriving from increased levels in mononuclear inflammatory cells. Dysregulated polyamine homeostasis may contribute to chronic UC by altering immune responses and increasing oxidative stress.

In vivo analysis of gut function and disease changes in a zebrafish larvae model of inflammatory bowel disease: a feasibility study

BACKGROUND

The aim of this study was to develop a model of inflammatory bowel disease (IBD) in zebrafish larvae, together with a method for the rapid assessment of gut morphology and function in vivo thereby enabling medium-throughput compound screening.

METHODS

Assays were performed using larval zebrafish from 3-8 days postfertilization (d.p.f.) in 96-well plates. Gut morphology and peristalsis were observed in vivo using fluorescent imaging following ingestion of fluorescent dyes. IBD was induced by addition of 2,4,6-trinitrobenzenesulfonic acid (TNBS) to the medium within the well. Pathology was assessed in vivo using fluorescent imaging and postmortem by histology, immunohistochemistry, and electron microscopy. Therapeutic compounds were evaluated by coadministration with TNBS.

RESULTS

A novel method of investigating gut architecture and peristalsis was devised using fluorescent imaging of live zebrafish larvae. Archetypal changes in gut architecture consistent with colitis were observed throughout the gut. Significant changes in goblet cell number and tumor necrosis factor alpha (TNF-alpha) antibody staining were used to quantify disease severity and rescue. Prednisolone and 5-amino salicylic acid treatment ameliorated the disease changes. Candidate therapeutic compounds (NOS inhibitors, thalidomide, and parthenolide) were assessed and a dissociation was observed between efficacy assessed using a single biochemical measure (TNF-alpha staining) versus an assessment of the entire disease state.

CONCLUSIONS

Gut physiology and pathology relevant to human disease state can be rapidly modeled in zebrafish larvae. The model is suitable for medium-throughput chemical screens and is amenable to genetic manipulation, hence offers a powerful novel premammalian adjunct to the study of gastrointestinal disease.

Oral nitrite ameliorates dextran sulfate sodium-induced acute experimental colitis in mice

Inflammatory bowel diseases (IBDs) such as Crohn's disease and ulcerative colitis are chronic inflammatory disorders of the intestinal tract with excessive production of cytokines, adhesion molecules, and reactive oxygen species. Although nitric oxide (NO) is reported to be involved in the onset and progression of IBDs, it remains controversial as to whether NO is toxic or protective in experimental colitis. We investigated the effects of oral nitrite as a NO donor on dextran sulfate sodium (DSS)-induced acute colitis in mice. Mice were fed DSS in their drinking water with or without nitrite for up to 7days. The severity of colitis was assessed by disease activity index (DAI) observed over the experimental period, as well as by the other parameters, including colon lengths, hematocrit levels, and histological scores at day 7. DSS treatment induced severe colitis by day 7 with exacerbation in DAI and histological scores. We first observed a significant decrease in colonic nitrite levels and increase in colonic TNF-alpha expression at day 3 after DSS treatment, followed by increased colonic myeloperoxidase (MPO) activity and increased colonic expressions of both inducible NO synthase (iNOS) and heme oxygenase-1 (HO-1) at day 7. Oral nitrite supplementation to colitis mice reversed colonic nitrite levels and TNF-alpha expression to that of normal control mice at day 3, resulting in the reduction of MPO activity as well as iNOS and HO-1 expressions in colonic tissues with clinical and histological improvements at day 7. These results suggest that oral nitrite inhibits inflammatory process of DSS-induced experimental colitis by supplying nitrite-derived NO instead of impaired colonic NOS activity.

Asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), arginine, and 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha) level in patients with inflammatory bowel diseases

BACKGROUND

Intestinal microvessels of patients with inflammatory bowel disease (IBD) show microvascular endothelial dysfunction. It may contribute to reduced perfusion, poor ulcer healing, and sustained chronic inflammation. The aim of the study was to assess endothelial dysfunction and oxidative stress markers in patients with IBD.

METHODS

Serum levels of asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), arginine, and 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha) were measured in 31 consecutive patients with ulcerative colitis (UC) and 32 with Crohn's disease (CD). Apparently healthy subjects served as age- and sex-matched controls. Associations between these markers and the disease activity and laboratory variables were evaluated.

RESULTS

ADMA, SDMA, and 8-iso-PGF2alpha levels were increased in the IBD group as compared to the control group and higher in patients with CD than UC (P < 0.05 for all comparisons). Arginine levels were similar in all the groups. In the CD and UC groups ADMA and SDMA showed positive correlation with 8-iso-PGF2alpha (r from 0.47-0.67; P < 0.01 for all comparisons). ADMA and SDMA correlated positively with the CD activity (r = 0.4, P = 0.025; r = 0.4, P = 0.024, respectively) and the 8-iso-PGF2alpha level correlated positively with the UC activity (r = 0.4, P = 0.026).

CONCLUSIONS

This is the first study to show that in patients with IBD there is enhanced ADMA generation that might be associated with oxidative stress, and these effects are more pronounced in the CD group.

Increased serum levels of L-arginine in ulcerative colitis and correlation with disease severity

BACKGROUND

L-arginine (L-Arg) is a semi-essential amino acid that is the substrate for both nitric oxide and polyamine synthesis. Cellular uptake of L-Arg is an active transport process that is subject to competitive inhibition by L-ornithine (L-Orn) and L-lysine (L-Lys). We investigated L-Arg utilization in patients with ulcerative colitis (UC).

METHODS

Serum was collected from 14 normal controls and 22 UC patients with pancolitis of moderate or severe activity by histopathology score. The Mayo Disease Activity Index (DAI) and endoscopy subscore were assessed. Serum amino acid levels were measured by high-performance liquid chromatography. Arginine availability index (AAI) was defined as [L-Arg]/([L-Orn] + [L-Lys]).

RESULTS

Serum L-Arg levels were significantly associated with histopathologic grade (P = 0.001). L-Arg levels were increased in subjects with severe colitis when compared to those with moderate colitis or normal mucosa. L-Orn + L-Lys levels were also increased in severe colitis, so that AAI was not significantly increased. L-Arg levels were also strongly associated with the endoscopy subscore (P < 0.001). There was a strong correlation between DAI and L-Arg levels (r = 0.656, P < 0.001).

CONCLUSIONS

Serum L-Arg levels correlate with UC disease severity but availability is not increased due to competitive inhibition by L-Orn and L-Lys. Our findings suggest that L-Arg uptake by cells in the inflamed colon is defective, which may contribute to the pathogenesis of UC. Studies delineating the mechanism of uptake inhibition could enhance our understanding of UC or lead to novel treatment options.

Minocycline attenuates 5-fluorouracil-induced small intestinal mucositis in mouse model

Minocycline exerts anti-inflammatory and anti-apoptotic effects distinct from its antimicrobial function. In this study we investigated the effect of this drug on chemotherapy-induced gut damage. Body weight loss results, diarrhea scores, and villi measurements showed that minocycline attenuated the severity of intestinal mucositis induced by 5-fluorouracil (5-FU). Minocycline repressed the expression of TNF-alpha, IL-1beta, and iNOS, decreased the apoptotic index, and inhibited poly(ADP-ribose) polymerase-1 (PARP-1) activity in the mouse small intestine. In vitro experiments showed that minocycline suppressed the upregulation of PARP-1 activity in enterocyte IEC-6 cells treated with 5-FU. In addition, minocycline treatment appeared to enhance the antitumor effects of 5-FU in tumor CT-26 xenograft mice. Our results indicate that minocycline protects mice from gut injury induced by 5-FU and enhances the antitumor effects of 5-FU in xenograft mice. These observations suggest that minocycline treatment may benefit patients undergoing standard cancer chemotherapy by alleviating chemical-associated intestinal mucositis.

Protective effects of lithium on acetic acid-induced colitis in rats

Inflammatory bowel disease (IBD) is a multifactorial disease with unknown etiology characterized by oxidative stress, leukocyte infiltration, and rise in inflammatory cytokines such as tumor necrosis factor (TNF-alpha). Lithium, as a therapeutic agent for bipolar disorder, exerts some anti-inflammatory properties. In this study we have investigated the effects of lithium on acetic-acid-induced colitis in rats. Lithium (5, 10, and 20 mg/kg) was administered 1 h before the introduction of acetic acid. Colonic status was investigated 24 h following colitis induction through macroscopic, histological, and biochemical analyses. Lithium (20 mg/kg) ameliorated macroscopic and microscopic scores. These observations were accompanied by a reduction in the degree of both neutrophil infiltration, indicated by decreased myeloperoxidase activity, and lipid peroxidation, as measured by a decline in malondialdehyde content in inflamed colon as well as a decrease in TNF-alpha levels. These findings suggest that lithium exerts beneficial effects on experimental colitis and therefore might be useful in the treatment of IBD.

Transitions at CpG dinucleotides, geographic clustering of TP53 mutations and food availability patterns in colorectal cancer

BACKGROUND

Colorectal cancer is mainly attributed to diet, but the role exerted by foods remains unclear because involved factors are extremely complex. Geography substantially impacts on foods. Correlations between international variation in colorectal cancer-associated mutation patterns and food availabilities could highlight the influence of foods on colorectal mutagenesis.

METHODOLOGY

To test such hypothesis, we applied techniques based on hierarchical clustering, feature extraction and selection, and statistical pattern recognition to the analysis of 2,572 colorectal cancer-associated TP53 mutations from 12 countries/geographic areas. For food availabilities, we relied on data extracted from the Food Balance Sheets of the Food and Agriculture Organization of the United Nations. Dendrograms for mutation sites, mutation types and food patterns were constructed through Ward's hierarchical clustering algorithm and their stability was assessed evaluating silhouette values. Feature selection used entropy-based measures for similarity between clusterings, combined with principal component analysis by exhaustive and heuristic approaches.

CONCLUSION/SIGNIFICANCE

Mutations clustered in two major geographic groups, one including only Western countries, the other Asia and parts of Europe. This was determined by variation in the frequency of transitions at CpGs, the most common mutation type. Higher frequencies of transitions at CpGs in the cluster that included only Western countries mainly reflected higher frequencies of mutations at CpG codons 175, 248 and 273, the three major TP53 hotspots. Pearson's correlation scores, computed between the principal components of the datamatrices for mutation types, food availability and mutation sites, demonstrated statistically significant correlations between transitions at CpGs and both mutation sites and availabilities of meat, milk, sweeteners and animal fats, the energy-dense foods at the basis of "Western" diets. This is best explainable by differential exposure to nitrosative DNA damage due to foods that promote metabolic stress and chronic inflammation.

Metabolic assessment of gradual development of moderate experimental colitis in IL-10 deficient mice

Evidence has linked genetic predisposition and environmental exposures to the worldwide pandemic of inflammatory bowel diseases (IBD), but underlying biochemical events remain largely undefined. Here, we studied the gradual development of colitis in Interleukin 10 deficient mice using a combination of (i) histopathological analysis of intestinal sections, (ii) metabolic profiling of blood plasma, and (iii) measurement of plasma inflammatory biomarkers. Data integration using chemometric tools, including Independent Component Analysis, provided a new strategy for measuring and mapping the metabolic effects associated with the development of intestinal inflammation at the age of 1, 8, 16, and 24 weeks. Chronic inflammation appeared at 8 weeks and onward, and was associated with altered cecum and colon morphologies and increased inflammatory cell infiltration into the mucosa and the submucosa. Blood plasma profiles provided additional evidence of loss of energy homeostasis, impaired metabolism of lipoproteins and glycosylated proteins. In particular, IL-10-/-mice were characterized by decreased levels of VLDL and increased concentrations of LDL and polyunsaturated fatty acids, which are related to the etiology of IBD. Moreover, higher levels of lactate, pyruvate, citrate and lowered glucose suggested increased fatty acid oxidation and glycolysis, while higher levels of free amino acids reflected muscle atrophy, breakdown of proteins and interconversions of amino acids to produce energy. These integrated system investigations demonstrate the potential of metabonomics for investigating the mechanistic basis of IBD, and it will provide novel avenues for management of IBD.

Non-invasive monitoring of redox status in mice with dextran sodium sulphate-induced colitis

Change of redox status is associated with colitis induced by dextran sodium sulphate (DSS). This study monitored redox status in DSS-induced colitis in mice using in vivo electron spin resonance (ESR) spectroscopy with nitroxyl probes. Colitis was induced in male ICR mice by supplementing their drinking water with 3% DSS for 3, 5 or 7 days. The ESR signal decay rate of carbamoyl-PROXYL administered into the rectum was enhanced by DSS treatment and the enhancement on day 7 was suppressed by membrane-permeable antioxidants, tiron and dimethylsulphoxide and a membrane-impermeable antioxidant, mannitol. The enhancement on day 5 was suppressed by tiron and dimethylsulphoxide, while that on day 3 was inhibited only by tiron. These results suggest that redox change occurs in or around of epithelial cells on day 7, but only intracellularly on day 5, and that redox change such as generation of less reactive radicals occurs only intracellularly on day 3.

Pitavastatin prevents intestinal ischemia/reperfusion-induced bacterial translocation and lung injury in atherosclerotic rats with hypoadiponectinemia

BACKGROUND

Atherosclerosis with hypoadiponectinemia can be further aggravated by intestinal ischemia/reperfusion (II/R)-induced injuries, such as bacterial translocation and lung injury. We investigated the effect of statin administration on the risk of II/R-induced injury in atherosclerotic rats with hypoadiponectinemia.

METHODS

Wistar rats were divided into 4 groups: (1) the Normal group (normal diet), (2) the Chol group (2% high cholesterol diet), (3) the St-1w group, and (4) the St-2w group (Chol group plus pitavastatin administration for 1 or 2 weeks, respectively). The serum concentrations of lipids and adiponectin were measured preoperatively. After midline laparotomy (time, T0), the superior mesenteric artery was occluded with a microvascular clamp for 30 min, followed by 360 min of reperfusion (T1). Intestinal and lung nitric oxide (NO) concentrations were measured. Intestinal injury was assessed by microcirculatory flow, histology, and permeability. Bacterial translocation was assessed by analysis of serum peptidoglycan concentration. Lung injury was assessed by histologic examination, pulmonary permeability index, and wet/dry lung weight ratio.

RESULTS

The 2-week administration of statins with high-cholesterol feeding (St-2w group) improved hypoadiponectinemia to levels similar to those of the Normal group. Intestinal and lung NO concentrations were significantly lower at T1 in the Normal and St-2w groups than in the Chol group. Statin administration improved poor recovery of intestinal microcirculatory flow in the Chol group. At T1, intestinal and lung injuries were significantly aggravated and serum peptidoglycan concentration was significantly elevated in the Chol group compared with the Normal and St-2w groups. The 1-week administration of statins had no significant influence on serum adiponectin levels, tissue NO concentration, or tissue injury.

CONCLUSION

Administration of pitavastatin reduces the risk of II/R-induced injury in atherosclerotic rats with hypoadiponectinemia by improving hypoadiponectinemia and inhibiting inducible NO synthase-produced NO. Furthermore, preoperative improvement of hypoadiponectinemia may be important as an index of the protective effect of pitavastatin for II/R-induced injury in atherosclerotic rats with hypoadiponectinemia.

Prophylactic role of curcumin in dextran sulfate sodium (DSS)-induced ulcerative colitis murine model

We have addressed in this study the possible protective role of the main principle of turmeric pigment; curcumin on a murine model of ulcerative colitis (UC). Colitis was induced by administration of dextran sulfate sodium (DSS) (3% W/V) in drinking water to male Swiss albino rats for 5 consecutive days. DSS challenge induced UC model that was well characterized morphologically and biochemically. DSS produced shrinkage of colon length and increased the relative colon weight/length ratio accompanied by mucosal edema and bloody stool. Histologically, DSS produced submucosal erosions, ulceration, inflammatory cell infiltration and crypt abscess as well as epithelioglandular hyperplasia. The model was confirmed biochemically, and the test battery entailed elevated serum tumor necrosis factor (TNF-alpha) and colonic activity of myleoperoxidase (MPO). Colonic glutathione-S-transferase (GST) activity and its substrate concentration; GSH, were notably reduced, while lipid peroxidation, expressed as malondialdehyde (MDA) level, and total nitric oxide (NO) were significantly increased. Prior administration of curcumin (100mg/kg, IP) for 7 consecutive days ahead of DSS challenge mitigated the injurious effects of DSS and ameliorated all the altered biochemical parameters. These results suggest that curcumin could possibly have a protective role in ulcerative colitis probably via regulation of oxidant/anti-oxidant balance and modulation of the release of some inflammatory endocoids, namely TNF-alpha and NO.

Minocycline attenuates experimental colitis in mice by blocking expression of inducible nitric oxide synthase and matrix metalloproteinases

In addition to its antimicrobial activity, minocycline exerts anti-inflammatory effects in several disease models. However, whether minocycline affects the pathogenesis of inflammatory bowel disease has not been determined. We investigated the effects of minocycline on experimental colitis and its underlying mechanisms. Acute and chronic colitis were induced in mice by treatment with dextran sulfate sodium (DSS) or trinitrobenzene sulfonic acid (TNBS), and the effect of minocycline on colonic injury was assessed clinically and histologically. Prophylactic and therapeutic treatment of mice with minocycline significantly diminished mortality rate and attenuated the severity of DSS-induced acute colitis. Mechanistically, minocycline administration suppressed inducible nitric oxide synthase (iNOS) expression and nitrotyrosine production, inhibited proinflammatory cytokine expression, repressed the elevated mRNA expression of matrix metalloproteinases (MMPs) 2, 3, 9, and 13, diminished the apoptotic index in colonic tissues, and inhibited nitric oxide production in the serum of mice with DSS-induced acute colitis. In DSS-induced chronic colitis, minocycline treatment also reduced body weight loss, improved colonic histology, and blocked expression of iNOS, proinflammatory cytokines, and MMPs from colonic tissues. Similarly, minocycline could ameliorate the severity of TNBS-induced acute colitis in mice by decreasing mortality rate and inhibiting proinflammatory cytokine expression in colonic tissues. These results demonstrate that minocycline protects mice against DSS- and TNBS-induced colitis, probably via inhibition of iNOS and MMP expression in intestinal tissues. Therefore, minocycline is a potential remedy for human inflammatory bowel diseases.

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.