Eicosanoids and the gastrointestinal tract

Identifying serum metabolite biomarkers for autoimmune diseases: a two-sample mendelian randomization and meta-analysis

Background

Extensive evidence suggests a link between alterations in serum metabolite composition and various autoimmune diseases (ADs). Nevertheless, the causal relationship underlying these correlations and their potential utility as dependable biomarkers for early AD detection remain uncertain.

Objective

The objective of this study was to employ a two-sample Mendelian randomization (MR) approach to ascertain the causal relationship between serum metabolites and ADs. Additionally, a meta-analysis incorporating data from diverse samples was conducted to enhance the validation of this causal effect.

Materials and methods

A two-sample MR analysis was performed to investigate the association between 486 human serum metabolites and six prevalent autoimmune diseases: systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), inflammatory bowel disease (IBD), dermatomyositis (DM), type 1 diabetes (T1D), and celiac disease (CeD). The inverse variance weighted (IVW) model was employed as the primary analytical technique for the two-sample MR analysis, aiming to identify blood metabolites linked with autoimmune diseases. Independent outcome samples were utilized for further validation of significant blood metabolites. Additional sensitivity analyses, including heterogeneity test, horizontal pleiotropy test, and retention rate analysis, were conducted. The results from these analyses were subsequently meta-integrated. Finally, metabolic pathway analysis was performed using the KEGG and Small Molecule Pathway Databases (SMPD).

Results

Following the discovery and replication phases, eight metabolites were identified as causally associated with various autoimmune diseases, encompassing five lipid metabolism types: 1-oleoylglycerophosphoethanolamine, 1-arachidonoylglycerophosphoethanolamine, 1-myristoylglycerophosphocholine, arachidonate (20:4 n6), and glycerol. The meta-analysis indicated that three out of these eight metabolites exhibited a protective effect, while the remaining five were designated as pathogenic factors. The robustness of these associations was further confirmed through sensitivity analysis. Moreover, an investigation into metabolic pathways revealed a significant correlation between galactose metabolism and autoimmune diseases.

Conclusion

This study revealed a causal relationship between lipid metabolites and ADs, providing novel insights into the mechanism of AD development mediated by serum metabolites and possible biomarkers for early diagnosis.

Acetylsalicylic Acid Supplementation Affects the Neurochemical Phenotyping of Porcine Duodenal Neurons

Aspirin (ASA) is a popular nonsteroidal anti-inflammatory drug (NSAID), which exerts its therapeutic properties through the inhibition of cyclooxygenase (COX) isoform 2 (COX-2), while the inhibition of COX-1 by ASA results in the formation of gastrointestinal side effects. Due to the fact that the enteric nervous system (ENS) is involved in the regulation of digestive functions both in physiological and pathological states, the aim of this study was to determine the influence of ASA on the neurochemical profile of enteric neurons in the porcine duodenum. Our research, conducted using the double immunofluorescence technique, proved an increase in the expression of selected enteric neurotransmitters in the duodenum as a result of ASA treatment. The mechanisms of the visualized changes are not entirely clear but are probably related to the enteric adaptation to inflammatory conditions resulting from aspirin supplementation. A detailed understanding of the role of the ENS in the development of drug-induced inflammation will contribute to the establishment of new strategies for the treatment of NSAID-induced lesions.

Gastrointestinal permeability and inflammatory status of preweaning dairy calves in response to decreasing the ratio of n-6 to n-3 fatty acid in milk replacer

The ratio of n-6 to n-3 fatty acid (FA) is between 2 and 10 times higher in milk replacer (MR) than in whole milk, which may promote inflammation and compromise the integrity of the intestinal epithelium. To evaluate how decreasing the n-6:n-3 FA ratio of MR affects gastrointestinal (GIT) permeability and inflammatory status, 30 dairy calves (2.8 ± 1.06 d of age; mean ± standard deviation) were randomly assigned to be fed an MR with an n-6:n-3 FA ratio of 40:1 (CON; 29.3% crude fat of DM; n = 15) or 6.5:1 (n-3; 29.1% crude fat of DM; n = 15). Calves were fed 7.0 L/d in 2 meals. Calves were weighed and fecal consistency was analyzed weekly. On d 22, calves were administered Cr-EDTA, lactulose, and d-mannitol to assess GIT permeability. Blood and total urine were sequentially collected for 6 and 24 h, respectively, and analyzed for marker content. Whole blood collected 4 h after the meal was subjected to an ex vivo lipopolysaccharide (LPS) challenge to evaluate cytokine secretion from blood cells. Calves were euthanized on d 25 for collection of intestinal tissue samples. Tissue samples were processed to assess FA composition by gas chromatography, histomorphology by bright-field microscopy, and gene expression of tight junction proteins, lipid metabolism enzymes, and immune molecules by real-time quantitative PCR. Data were analyzed using PROC GLIMMIX in SAS (version 9.4, SAS Institute Inc.). Growth performance and fecal consistency were unaffected. Calves fed MR with a lower ratio of n-6 to n-3 FA had 2-fold higher n-3 FA contents and 2-fold lower ratios of n-6 to n-3 FA in proximal jejunum and ileum tissues. Total urinary recovery (0-24 h relative to marker administration) and plasma concentrations of the markers were unaffected. Expression of TJP1 tended to be higher in proximal jejunum tissue and lower in ileum tissue of n-3 calves. The expression of TLR4 and TNFA tended to be higher and CD14 was higher in ileum tissue of n-3 calves. Plasma concentrations of interleukin-4 were decreased in response to the ex vivo LPS challenge in n-3 calves. Histomorphology and GIT permeability were largely unaffected by treatment. Furthermore, the inclusion of linseed and algae oil may promote inflammation, as suggested by greater concentrations of the acute-phase proteins haptoglobin and serum amyloid A postprandially, demonstrating that fat sources should be evaluated for their suitability for MR formulations. Understanding how MR composition affects dairy calf health may improve nutritional strategies on farm.

Gut homeostasis, injury, and healing: New therapeutic targets

The integrity of the gastrointestinal mucosa plays a crucial role in gut homeostasis, which depends upon the balance between mucosal injury by destructive factors and healing via protective factors. The persistence of noxious agents such as acid, pepsin, nonsteroidal anti-inflammatory drugs, or Helicobacter pylori breaks down the mucosal barrier and injury occurs. Depending upon the size and site of the wound, it is healed by complex and overlapping processes involving membrane resealing, cell spreading, purse-string contraction, restitution, differentiation, angiogenesis, and vasculogenesis, each modulated by extracellular regulators. Unfortunately, the gut does not always heal, leading to such pathology as peptic ulcers or inflammatory bowel disease. Currently available therapeutics such as proton pump inhibitors, histamine-2 receptor antagonists, sucralfate, 5-aminosalicylate, antibiotics, corticosteroids, and immunosuppressants all attempt to minimize or reduce injury to the gastrointestinal tract. More recent studies have focused on improving mucosal defense or directly promoting mucosal repair. Many investigations have sought to enhance mucosal defense by stimulating mucus secretion, mucosal blood flow, or tight junction function. Conversely, new attempts to directly promote mucosal repair target proteins that modulate cytoskeleton dynamics such as tubulin, talin, Ehm², filamin-a, gelsolin, and flightless I or that proteins regulate focal adhesions dynamics such as focal adhesion kinase. This article summarizes the pathobiology of gastrointestinal mucosal healing and reviews potential new therapeutic targets.

Unique Regulation of Intestinal Villus Epithelial Cl-/HCO3- Exchange by Cyclooxygenase Pathway Metabolites of Arachidonic Acid in a Mouse Model of Spontaneous Ileitis

Electrolytes (NaCl) and fluid malabsorption cause diarrhea in inflammatory bowel disease (IBD). Coupled NaCl absorption, mediated by Na⁺/H⁺ and Cl^-/HCO₃^- exchanges on the intestinal villus cells brush border membrane (BBM), is inhibited in IBD. Arachidonic acid metabolites (AAMs) formed via cyclooxygenase (COX) or lipoxygenase (LOX) pathways are elevated in IBD. However, their effects on NaCl absorption are not known. We treated SAMP1/YitFc (SAMP1) mice, a model of spontaneous ileitis resembling human IBD, with Arachidonyl Trifluoro Methylketone (ATMK, AAM inhibitor), or with piroxicam or MK-886, to inhibit COX or LOX pathways, respectively. Cl^-/HCO₃^- exchange, measured as DIDS-sensitive ³⁶Cl uptake, was significantly inhibited in villus cells and BBM vesicles of SAMP1 mice compared to AKR/J controls, an effect reversed by ATMK. Piroxicam, but not MK-886, also reversed the inhibition. Kinetic studies showed that inhibition was secondary to altered K_m with no effects on V_max. Whole cell or BBM protein levels of Down-Regulated in Adenoma (SLC26A3) and putative anion transporter-1 (SLC26A6), the two key BBM Cl^-/HCO₃^- exchangers, were unaltered. Thus, inhibition of villus cell Cl^-/HCO₃^- exchange by COX pathway AAMs, such as prostaglandins, via reducing the affinity of the exchanger for Cl^-, and thereby causing NaCl malabsorption, could significantly contribute to IBD-associated diarrhea.

Role of arachidonic acid-derived eicosanoids in intestinal innate immunity

Arachidonic acid (ARA), an n-6 essential fatty acid, plays an important role in human and animal growth and development. The ARA presents in the membrane phospholipids can be released by phospholipase A2. These free arachidonic acid molecules are then used to produce eicosanoids through three different pathways. Previous studies have demonstrated that eicosanoids have a wide range of physiological functions. Although they are generally considered to be pro-inflammatory molecules, recent advances have elucidated they have an effect on innate immunity via regulating the development, and differentiation of innate immune cells and the function of the intestinal epithelial barrier. Here, we review eicosanoids generation in intestine and their role in intestinal innate immunity, focusing on intestinal epithelial barrier, innate immune cell in lamina propria (LP) and their crosstalk.

Host-Parasite Interactions Promote Disease Tolerance to Intestinal Helminth Infection

Parasitic helminths are among the most pervasive pathogens of the animal kingdom. To complete their life cycle, these intestinal worms migrate through host tissues causing significant damage in their wake. As a result, infection can lead to malnutrition, anemia and increased susceptibility to co-infection. Despite repeated deworming treatment, individuals living in endemic regions remain highly susceptible to re-infection by helminths, but rarely succumb to excessive tissue damage. The chronicity of infection and inability to resist numerous species of parasitic helminths that have co-evolved with their hosts over millenia suggests that mammals have developed mechanisms to tolerate this infectious disease. Distinct from resistance where the goal is to destroy and eliminate the pathogen, disease tolerance is an active process whereby immune and structural cells restrict tissue damage to maintain host fitness without directly affecting pathogen burden. Although disease tolerance is evolutionary conserved and has been well-described in plant systems, only recently has this mode of host defense, in its strictest sense, begun to be explored in mammals. In this review, we will examine the inter- and intracellular networks that support disease tolerance during enteric stages of parasitic helminth infection and why this alternative host defense strategy may have evolved to endure the presence of non-replicating pathogens and maintain the essential functions of the intestine.

Lactobacillus rhamnosus GG increases cyclooxygenase-2 expression and prostaglandin E2 secretion in colonic myofibroblasts via a MyD88-dependent mechanism during homeostasis

Prostaglandin E2 (PGE₂ ) plays a critical role in intestinal mucosal tolerance and barrier integrity. Cyclooxygenase-2 (COX-2)-dependent PGE₂ production involves mobilisation of arachidonic acid. Lactobacillus rhamnosus GG (LbGG) is one of the most widely used probiotics reported to colonise the colonic mucosa. LbGG contributes to the protection of the small intestine against radiation injury through the repositioning of mucosal COX-2 expressing cells. However, it is unknown if LbGG modulates PGE₂ production in the colonic mucosa under homeostasis and the major cellular elements involved in these processes. Colonic epithelial and CD90⁺ mesenchymal stromal cells, also known as (myo) fibroblasts (CMFs), are abundant innate immune cells in normal colonic mucosa able to produce PGE₂ . Herein, we tested the hypothesis that under colonic mucosal homeostasis, LbGG modulates the eicosanoid pathway resulting in increased PGE₂ production in both epithelial and stromal cells. Among the five tested human colonic epithelial cell lines, only exposure of Caco-2 to LbGG for 24 hr led to the mobilisation of arachidonic acid with concomitant increase in the components within the leukotriene and COX-2-dependent PGE₂ pathways. By contrast, CMFs isolated from the normal human colonic mucosa responded to LbGG with increased expression of COX-2 and PGE₂ in the prostaglandin pathway, but not 5-LO in the leukotriene pathway. Oral gavage of C57BL/6 mice for 5 days with LbGG (5 × 10⁸ Colony-Forming Unit (CFU)/dose) increased COX-2 expression in the colonic mucosa. The majority of cells upregulating COX-2 protein expression were located in the colonic lamina propria and colocalised with α-SMA⁺ cells corresponding to the CMF phenotype. This process was myeloid differentiation factor-88-dependent, because silencing of myeloid differentiation factor-88 expression in CMFs abrogated LbGG-induced upregulation of COX-2 in culture and in vivo. Taken together, our data suggest that LbGG increases release of COX-2-mediated PGE₂ , contributing to the maintenance of mucosal homeostasis in the colon and CMFs are among the major contributors to this process.

Mechanisms of curcumin-induced gastroprotection against ethanol-induced gastric mucosal lesions

BACKGROUND

Curcumin, a pleiotropic substance used for centuries in traditional medicine, exhibits antioxidant, anti-inflammatory and antiproliferative efficacy against various tumours, but the role of curcumin in gastroprotection is little studied. We determined the effect of curcumin against gastric haemorrhagic lesions induced by 75% ethanol and alterations in gastric blood flow (GBF) in rats with cyclooxygenase-1 (COX-1) and COX-2 activity inhibited by indomethacin, SC-560 or rofecoxib, inhibited NO-synthase activity, capsaicin denervation and blockade of TRPV1 receptors by capsazepine.

METHODS

One hour after ethanol administration, the gastric mucosal lesions were assessed by planimetry, the GBF was examined by H2 gas clearance, plasma gastrin was determined by radioimmunoassay, and the gastric mucosal mRNA expression of Cdx-2, HIF-1α, HO-1 and SOD 2 was analysed by RT-PCR.

RESULTS

Curcumin, in a dose-dependent manner, reduced ethanol-induced gastric lesions and significantly increased GBF and plasma gastrin levels. Curcumin-induced protection was completely reversed by indomethacin and SC-560, and significantly attenuated by rofecoxib, L-NNA, capsaicin denervation and capsazepine. Curcumin downregulated Cdx-2 and Hif-1α mRNA expression and upregulated HO-1 and SOD 2, and these effects were reversed by L-NNA and further restored by co-treatment of L-NNA with L-arginine.

CONCLUSIONS

Curcumin-induced protection against ethanol damage involves endogenous PG, NO, gastrin and CGRP released from sensory nerves due to activation of the vanilloid TRPV1 receptor. This protective effect can be attributed to the inhibition of HIF-1α and Cdx-2 expression and the activation of HO-1 and SOD 2 expression.

Arachidonic acid-induced Ca2+ entry and migration in a neuroendocrine cancer cell line

Background

Store-operated Ca²⁺ entry (SOCE) has been implicated in the migration of some cancer cell lines. The canonical SOCE is defined as the Ca²⁺ entry that occurs in response to near-maximal depletion of Ca²⁺ within the endoplasmic reticulum. Alternatively, arachidonic acid (AA) has been shown to induce Ca²⁺ entry in a store-independent manner through Orai1/Orai3 hetero-multimeric channels. However, the role of this AA-induced Ca²⁺ entry pathway in cancer cell migration has not been adequately assessed.

Methods

The present study investigated the involvement of AA-induced Ca²⁺ entry in migration in BON cells, a model gastro-enteropancreatic neuroendocrine tumor (GEPNET) cell line using pharmacological and gene knockdown methods in combination with live cell fluorescence imaging and standard migration assays.

Results

We showed that both the store-dependent and AA-induced Ca²⁺ entry modes could be selectively activated and that exogenous administration of AA resulted in Ca²⁺ entry that was pharmacologically distinct from SOCE. Also, whereas homomeric Orai1-containing channels appeared to largely underlie SOCE, the AA-induced Ca²⁺ entry channel required the expression of Orai3 as well as Orai1. Moreover, we showed that AA treatment enhanced the migration of BON cells and that this migration could be abrogated by selective inhibition of the AA-induced Ca²⁺ entry.

Conclusions

Taken together, these data revealed that an alternative Orai3-dependent Ca²⁺ entry pathway is an important signal for GEPNET cell migration.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0529-8) contains supplementary material, which is available to authorized users.

Pathophysiological Mechanisms of Gastrointestinal Toxicity

Humans swallow a great variety and often large amounts of chemicals as nutrients, incidental food additives and contaminants, drugs, and inhaled particles and chemicals, thus exposing the gastrointestinal tract to many potentially toxic substances. It serves as a barrier in many cases to protect other components of the body from such substances and infections. Fortunately, the gastrointestinal tract is remarkably robust and generally is able to withstand multiple daily assaults by the chemicals to which it is exposed. Some chemicals, however, can affect one or more aspects of the gastrointestinal tract to produce abnormal events that reflect toxicity. It is the purpose of this chapter to evaluate the mechanisms by which toxic chemicals produce their deleterious effects and to determine the consequences of the toxicity on integrity of gastrointestinal structure and function. Probably because of the intrinsic ability of the gastrointestinal tract to resist toxic chemicals, there is a paucity of data regarding gastrointestinal toxicology. It is therefore necessary in many cases to extrapolate toxic mechanisms from infectious processes, inflammatory conditions, ischemia, and other insults in addition to more conventional chemical sources of toxicity.

Anti-coagulative and gastrointestinal motility regulative activities of Fructus Aurantii Immaturus and its effective fractions

OBJECTIVE

Fructus Aurantii Immaturus (FAI) has been used in the treatment of gastrointestinal disorders (GIDs) in traditional Chinese medicine (TCM) for thousands of years, which also has been found to have effects on cardiovascular diseases (CVDs) in recent years. The current study aimed at investigating the anti-coagulative and gastrointestinal motility regulative activities of different fractions isolated from FAI, which may have both effects on gastrointestinal and cardiovascular systems, in the manners of network pharmacology analysis and experiments in vivo and in vitro.

METHODS

We obtained water decoction, volatile oils, alkaloids and flavonoids from FAI, which were identified by gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). Network pharmacological analysis was used to explore the relationship between the various types of chemical constituents, gene target and biological pathways of FAI. Then, the effective fractions in terms of anti-coagulative and gastrointestinal motility regulative activities were investigated by the experiment of rabbit intestinal smooth muscles contraction, mice small intestine propulsion rate and blood-clotting time, and verified by the blood stasis model.

RESULTS

From the Network pharmacological analysis, the flavonoids were predicted to be the main active ingredients on gastrointestinal and cardiovascular systems. Experimental results also showed that flavonoids could significantly increase the small intestine propulsion rate and extend the blood-clotting time of mice. The Flavonoids could alleviate the increased fractional shortening (FS), left ventricular outflow, hematocrit and fibrinogen, and ameliorate the pathological changes of myocardial tissues caused by blood stasis.

CONCLUSION

These findings indicated that flavonoids in FAI might be the main effective fractions on gastrointestinal motility and anti-coagulation.

Protective Effects of Manassantin A against Ethanol-Induced Gastric Injury in Rats

Manassantin A, a neolignan isolated from Saururus chinensis, is a major phytochemical compound that has various biological activities, including anti-inflammatory, neuroleptic, and human acyl-CoA : cholesterol acyltransferase (ACAT) inhibitory activities. In this study, we investigated the protective effects of manassantin A against ethanol-induced acute gastric injury in rats. Gastric injury was induced by intragastric administration of 5 mL/kg body weight of absolute ethanol to each rat. The positive control group and the manassantin A group were given oral doses of omeprazole (20 mg/kg) or manassantin A (15 mg/kg), respectively, 1 h prior to the administration of absolute ethanol. Our examinations revealed that manassantin A pretreatment reduced ethanol-induced hemorrhage, hyperemia, and epithelial cell loss in the gastric mucosa. Manassantin A pretreatment also attenuated the increased lipid peroxidation associated with ethanol-induced acute gastric lesions, increased the mucosal glutathione (GSH) content, and enhanced the activities of antioxidant enzymes. The levels of pro-inflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1β were clearly decreased in the manassantin A-pretreated group. In addition, manassantin A pretreatment enhanced the levels of cyclooxygenase (COX)-1, COX-2, and prostaglandin E2 (PGE2) and reduced the inducible nitric oxide synthase (iNOS) overproduction and nuclear factor kappa B (NF-κB) phosphorylation. Collectively, these results indicate that manassantin A protects the gastric mucosa from ethanol-induced acute gastric injury, and suggest that these protective effects might be associated with COX/PGE2 stimulation, inhibition of iNOS production and NF-κB activation, and improvements in the antioxidant and anti-inflammatory status.

Gastrointestinal Parasites and the Neural Control of Gut Functions

Gastrointestinal motility and transport of water and electrolytes play key roles in the pathophysiology of diarrhea upon exposure to enteric parasites. These processes are actively modulated by the enteric nervous system (ENS), which includes efferent, and afferent neurons, as well as interneurons. ENS integrity is essential to the maintenance of homeostatic gut responses. A number of gastrointestinal parasites are known to cause disease by altering the ENS. The mechanisms remain incompletely understood. Cryptosporidium parvum, Giardia duodenalis (syn. Giardia intestinalis, Giardia lamblia), Trypanosoma cruzi, Schistosoma species and others alter gastrointestinal motility, absorption, or secretion at least in part via effects on the ENS. Recent findings also implicate enteric parasites such as C. parvum and G. duodenalis in the development of post-infectious complications such as irritable bowel syndrome, which further underscores their effects on the gut-brain axis. This article critically reviews recent advances and the current state of knowledge on the impact of enteric parasitism on the neural control of gut functions, and provides insights into mechanisms underlying these abnormalities.

EP4 Receptor-Associated Protein in Macrophages Ameliorates Colitis and Colitis-Associated Tumorigenesis

Prostaglandin E₂ plays important roles in the maintenance of colonic homeostasis. The recently identified prostaglandin E receptor (EP) 4–associated protein (EPRAP) is essential for an anti-inflammatory function of EP4 signaling in macrophages in vitro. To investigate the in vivo roles of EPRAP, we examined the effects of EPRAP on colitis and colitis-associated tumorigenesis. In mice, EPRAP deficiency exacerbated colitis induced by dextran sodium sulfate (DSS) treatment. Wild-type (WT) or EPRAP-deficient recipients transplanted with EPRAP-deficient bone marrow developed more severe DSS-induced colitis than WT or EPRAP-deficient recipients of WT bone marrow. In the context of colitis-associated tumorigenesis, both systemic EPRAP null mutation and EPRAP-deficiency in the bone marrow enhanced intestinal polyp formation induced by azoxymethane (AOM)/DSS treatment. Administration of an EP4-selective agonist, ONO-AE1-329, ameliorated DSS-induced colitis in WT, but not in EPRAP-deficient mice. EPRAP deficiency increased the levels of the phosphorylated forms of p105, MEK, and ERK, resulting in activation of stromal macrophages in DSS-induced colitis. Macrophages of DSS-treated EPRAP-deficient mice exhibited a marked increase in the expression of pro-inflammatory genes, relative to WT mice. By contrast, forced expression of EPRAP in macrophages ameliorated DSS-induced colitis and AOM/DSS-induced intestinal polyp formation. These data suggest that EPRAP in macrophages functions crucially in suppressing colonic inflammation. Consistently, EPRAP-positive macrophages were also accumulated in the colonic stroma of ulcerative colitis patients. Thus, EPRAP may be a potential therapeutic target for inflammatory bowel disease and associated intestinal tumorigenesis.

Inflammatory bowel disease (IBD) is one of the most prevalent and serious gastrointestinal diseases in Western countries and associates with cancer development. EP4 receptor signaling can suppress intestinal inflammation and shows promise as a target for the development of novel therapies for IBD. To date, however, the lack of detailed molecular targets has hampered the development of effective drugs. This study focused on EPRAP, a novel EP4 receptor–associated protein, implicated in its signaling pathway. The generation of EPRAP-gene mutated mice permitted exploration of EPRAP functions in vivo. In addition, EPRAP was localized in stromal macrophages of ulcerative colitis patients. This study revealed that EPRAP in macrophage participates critically in EP4 receptor signaling-mediated inhibition of intestinal inflammation. The macrophage EP4–EPRAP axis thus comprises a novel therapeutic target for IBD.

Heterotopic Gastric Mucosa in the Distal Part of Esophagus in a Teenager: Case Report

Heterotopic gastric mucosa (HGM) of the esophagus is a congenital anomaly consisting of ectopic gastric mucosa. It may be connected with disorders of the upper gastrointestinal tract, exacerbated by Helicobacter pylori. The diagnosis of HGM is confirmed via endoscopy with biopsy. Histopathology provides the definitive diagnosis by demonstrating gastric mucosa adjacent to normal esophageal mucosa. HGM located in the distal esophagus needs differentiation from Barrett's esophagus. Barrett's esophagus is a well-known premalignant injury for adenocarcinoma of the esophagus. Malignant progression of HGM occurs in a stepwise pattern, following the metaplasia-dysplasia-adenocarcinoma sequence.We present a rare case of a teenage girl with HGM located in the distal esophagus, associated with chronic gastritis and biliary duodenogastric reflux. Endoscopy combined with biopsies is a mandatory method in clinical evaluation of metaplastic and nonmetaplastic changes within HGM of the esophagus.

Dietary Marine n-3 PUFAs Do Not Affect Stress-Induced Visceral Hypersensitivity in a Rat Maternal Separation Model

BACKGROUND

Although never evaluated for efficacy, n-3 (ω-3) long-chain polyunsaturated fatty acids (LCPUFAs) are commercially offered as treatment for irritable bowel syndrome (IBS).

OBJECTIVE

This study was designed to investigate, in a mast cell-dependent model for visceral hypersensitivity, whether this pathophysiologic mechanism can be reversed by dietary LCPUFA treatment via peroxisome proliferator-activated receptor γ (PPARG) activation.

METHODS

Maternally separated rats were subjected to hypersensitivity-inducing acute stress at adult age. Reversal was attempted by protocols with tuna oil-supplemented diets [4% soy oil (SO) and 3% tuna oil (SO-T3) or 3% SO and 7% tuna oil (SO-T7)] and compared with control SO diets (7% or 10% SO) 4 wk after stress. The PPARG agonist rosiglitazone was evaluated in a 1 wk preventive protocol (30 mg · kg⁻¹ · d⁻¹). Erythrocytes were assessed to confirm LCPUFA uptake and tissue expression of lipoprotein lipase and glycerol kinase as indicators of PPARG activation. Colonic mast cell degranulation was evaluated by toluidine blue staining. In vitro, human mast cell line 1 (HMC-1) cells were pretreated with rosiglitazone, eicosapentaenoic acid, or docosahexaenoic acid, stimulated with phorbol 12-myristate 13-acetate (PMA) and calcium ionophore or compound 48/80 and evaluated for tumor necrosis factor α (TNF-α) and β-hexosaminidase release.

RESULTS

Stress led to visceral hypersensitivity in all groups. Hypersensitivity was not reversed by SO-T3 or control treatment [prestress vs. 24 h poststress vs. posttreatment area under the curve; 76 ± 4 vs. 128 ± 12 (P < 0.05) vs. 115 ± 14 and 82 ± 5 vs. 127 ± 16 (P < 0.01) vs. 113 ± 19, respectively]. Comparison of SO-T7 with its control showed similar results [74 ± 6 vs. 103 ± 13 (P < 0.05) vs. 115 ± 17 and 66 ± 3 vs. 103 ± 10 (P < 0.05) vs. 117 ± 11, respectively]. Erythrocytes showed significant LCPUFA uptake in the absence of colonic PPARG activation. Rosiglitazone induced increased PPARG target gene expression, but did not prevent hypersensitivity. Mast cell degranulation never differed between groups. Rosiglitazone and LCPUFAs significantly reduced PMA/calcium ionophore-induced TNF-α release but not degranulation of HMC-1 cells.

CONCLUSION

Dietary LCPUFAs did not reverse stress-induced visceral hypersensitivity in maternally separated rats. Although further research is needed, claims concerning LCPUFAs as a treatment option in IBS cannot be confirmed at this point and should be regarded with caution.

Comparison of selective and non selective cyclo-oxygenase 2 inhibitors in experimental colitis exacerbation: role of leukotriene B4 and superoxide dismutase

CONTEXT

Nonsteroidal anti-inflammatory drugs are considered one of the most important causes of reactivation of inflammatory bowel disease. With regard to selective cyclo-oxygenase 2 inhibitors, the results are controversial in experimental colitis as well as in human studies.

OBJECTIVES

The aim this study is to compare nonsteroidal anti-inflammatory drugs effects, selective and non selective cyclo-oxygenase 2 inhibitors, in experimental colitis and contribute to the understanding of the mechanisms which nonsteroidal anti-inflammatory drugs provoke colitis exacerbation.

METHODS

Six groups of rats: without colitis, with colitis, and colitis treated with celecoxib, ketoprofen, indometacin or diclofenac. Survival rates, hemoglobin, plasmatic albumin, colonic tissue of interleukin-1ß, interleukin-6, tumor necrosis factor alpha, prostaglandin E2, catalase, superoxide dismutase, thiobarbituric acid-reactive substances, chemiluminescence induced by tert-butil hydroperoxides, and tissue and plasmatic leukotriene B4 were determined.

RESULTS

The groups treated with diclofenac or indometacin presented lower survival rates, hemoglobin and albumin, higher tissue and plasmatic leukotriene B4 and tissue superoxide dismutase than the group treated with celecoxib. Ketoprofen presented an intermediary behavior between diclofenac/indometacin and celecoxib, concerning to survival rate and albumin. The groups without colitis, with colitis and with colitis treated with celecoxib showed leukotriene B4 and superoxide dismutase lower levels than the groups treated with nonselective cyclo-oxygenase 2 inhibitors.

CONCLUSIONS

Diclofenac and indometacin presented the highest degree of induced colitis exacerbation with nonsteroidal anti-inflammatory drugs, celecoxib did not show colitis exacerbation, and ketoprofen presented an intermediary behavior between diclofenac/indometacin and celecoxib. These results suggest that leukotriene B4 and superoxide dismutase can be involved in the exacerbation of experimental colitis by nonselective nonsteroidal anti-inflammatory drugs.

The role of proteases in pain

Proteinase-activated receptors (PARs) are a family of G protein-coupled receptor that are activated by extracellular cleavage of the receptor in the N-terminal domain. This slicing of the receptor exposes a tethered ligand which binds to a specific docking point on the receptor surface to initiate intracellular signalling. PARs are expressed by numerous tissues in the body, and they are involved in various physiological and pathological processes such as food digestion, tissue remodelling and blood coagulation. This chapter will summarise how serine proteinases activate PARs leading to the development of pain in several chronic pain conditions. The potential of PARs as a drug target for pain relief is also discussed.

The universe of arachidonic acid metabolites in inflammatory bowel disease: can we tell the good from the bad?

PURPOSE OF REVIEW

This review summarizes recent developments in the role of soluble mediators of inflammation, particularly arachidonic acid metabolites, in inflammatory bowel disease (IBD).

RECENT FINDINGS

The role of prostaglandin E2 in immune regulation has been better defined. Prostaglandin E2 promotes not only immune tolerance and epithelial homeostasis but also the proinflammatory Th17 pathway. Prostaglandin D2 has been established as promoting the resolution of inflammation in the gastrointestinal mucosa. The 12-lipoxygenase product hepoxilin A3 mediates the migration of neutrophils from the mucosa into the lumen.

SUMMARY

Recent studies of soluble mediators, especially arachidonic acid metabolites, have defined their proinflammatory and anti-inflammatory roles in IBD.

Metabolic profiling of somatic tissues from Monochamus alternatus (Coleoptera: Cerambycidae) reveals effects of irradiation on metabolism

A high-level of sexual sterility is of importance for the sterile insect technique (SIT). However, the use of high-dose-intensity gamma radiation to induce sterility has negative impacts not only on reproductive cells but also on somatic cells. In this study, we investigated the metabolite differences in somatic tissues between non-irradiated, 20-Gy-irradiated, and 40-Gy-irradiated male Monochamus alternatus, an important vector of the pathogenic nematode, Bursaphelenchus xylophilus, which kills Asian pines. The results showed that metabolite levels changed moderately in the 20-Gy samples but were markedly altered in the 40-Gy samples compared with the non-irradiated samples. Twenty-six and 53 metabolites were disturbed by 20-Gy and 40-Gy radiation, respectively. Thirty-six metabolites were found to be markedly altered in the 40-Gy samples but were not changed significantly in the 20-Gy samples. The comprehensive metabolomic disorders induced by 40-Gy radiation dysregulated six metabolic pathways involved in the life process. The findings presented in this manuscript will contribute to our knowledge of the characteristic metabolic changes associated with gamma-radiation-induced damage to somatic cells and will allow for better exploration of the SIT for the control of this target pest.

Molecular docking and fluorescence characterization of benzothieno[3,2-d]pyrimidin-4-one sulphonamide thio-derivatives, a novel class of selective cyclooxygenase-2 inhibitors

The aims of this study were: (i) to explore the structure-activity relationship of some new anti-inflammatory benzothieno[3,2-d]pyrimidin-4-one sulphonamide thio-derivatives 1–11; and (ii) to evaluate the possibility of using the most active compounds as fluorescent probes to determine tumours or their progression. Therefore, to know the precise mechanism by which these compounds interact with cyclooxygenase (COX)-2 enzyme, a molecular docking study was carried out; to assess spectroscopic characteristics, their absorption and emission properties were determined. The results demonstrated that some derivatives of benzothieno[3,2-d] pyrimidine exhibit interesting anti-inflammatory properties related to interactions with active sites of COX-2 and are fluorescent. The antipyrine-bearing compound 4 displayed high COX-2 affinity (ΔG = −9.4) and good fluorescent properties (Φ_fl = 0.032). Thus, some members of this new class of anti-inflammatory may be promising for fluorescence imaging of cancer cells that express the COX-2 enzyme. Further in vitro and in vivo studies are needed to confirm this hypothesis.

Long-term differential changes in mouse intestinal metabolomics after γ and heavy ion radiation exposure

Tissue consequences of radiation exposure are dependent on radiation quality and high linear energy transfer (high-LET) radiation, such as heavy ions in space is known to deposit higher energy in tissues and cause greater damage than low-LET γ radiation. While radiation exposure has been linked to intestinal pathologies, there are very few studies on long-term effects of radiation, fewer involved a therapeutically relevant γ radiation dose, and none explored persistent tissue metabolomic alterations after heavy ion space radiation exposure. Using a metabolomics approach, we report long-term metabolomic markers of radiation injury and perturbation of signaling pathways linked to metabolic alterations in mice after heavy ion or γ radiation exposure. Intestinal tissues (C57BL/6J, female, 6 to 8 wks) were analyzed using ultra performance liquid chromatography coupled with electrospray quadrupole time-of-flight mass spectrometry (UPLC-QToF-MS) two months after 2 Gy γ radiation and results were compared to an equitoxic ⁵⁶Fe (1.6 Gy) radiation dose. The biological relevance of the metabolites was determined using Ingenuity Pathway Analysis, immunoblots, and immunohistochemistry. Metabolic profile analysis showed radiation-type-dependent spatial separation of the groups. Decreased adenine and guanosine and increased inosine and uridine suggested perturbed nucleotide metabolism. While both the radiation types affected amino acid metabolism, the ⁵⁶Fe radiation preferentially altered dipeptide metabolism. Furthermore, ⁵⁶Fe radiation caused upregulation of ‘prostanoid biosynthesis’ and ‘eicosanoid signaling’, which are interlinked events related to cellular inflammation and have implications for nutrient absorption and inflammatory bowel disease during space missions and after radiotherapy. In conclusion, our data showed for the first time that metabolomics can not only be used to distinguish between heavy ion and γ radiation exposures, but also as a radiation-risk assessment tool for intestinal pathologies through identification of biomarkers persisting long after exposure.

Crohn's disease in women

This article provides an overview of the obstetric and gynecological manifestations of Crohn’s disease (CD). High incidence of the new onset of the disease in young women in their reproductive years demands special concern from physicians involved in their treatment. Pregnant women with CD are considered high-risk patients, regardless of disease activity index, due to associated complications. Predominately described complications are premature birth, low birth weight, and congenital anomalies. To minimize the risk for adverse pregnancy/birth outcomes, it is recommended that remission be achieved before conception. Treatment of CD in pregnant women is similar to that among the nonpregnant population, and there is no valid reason to terminate it, since most of the drugs are proven to be safe. Women with CD who wish to conceive or are already pregnant need to be properly advised according to the newest guidelines on the subject, given by the European Crohn’s and Colitis Organization. Gynecological manifestations are another special feature of CD. They are important in that they may facilitate early recognition of the underlying disease, which usually stays unrecognized for years before intestinal manifestation; in this way, the underlying manifestations are often mistreated.

The multifaceted effects of omega-3 polyunsaturated Fatty acids on the hallmarks of cancer

Omega-3 polyunsaturated fatty acids, in particular eicosapentaenoic acid, and docosahexaenoic acid have been shown to have multiple beneficial antitumour actions that affect the essential alterations that dictate malignant growth. In this review we explore the putative mechanisms of action of omega-3 polyunsaturated fatty acid in cancer protection in relation to self-sufficiency in growth signals, insensitivity to growth-inhibitory signals, apoptosis, limitless replicative potential, sustained angiogenesis, and tissue invasion, and how these will hopefully translate from bench to bedside.

Effect of eicosapentaenoic acid-derived prostaglandin E3 on intestinal epithelial barrier function

Prostaglandins (PG) are inflammatory mediators derived from arachidonic or eicosapentaenoic acid giving rise to the 2-series or the 3-series prostanoids, respectively. Previously, we have observed that PGE2 disrupts epithelial barrier function. Considering the beneficial effect of fish oil consumption in intestinal inflammatory processes, the aim of this study was to assess the role of PGE3 on epithelial barrier function assessed from transepithelial electrical resistance and dextran fluxes in Caco-2 cells. The results indicate that PGE3 increased paracellular permeability (PP) to the same extent as PGE2, through the interaction with EP1 and EP4 receptors and with intracellular Ca(2+) and cAMP as the downstream targets. Moreover, we observed a redistribution of tight junction proteins, occludin and claudin-4. In conclusion, PGE3 is able to increase PP thus leading to reconsider the role of PGE2/PGE3 ratio in the beneficial effects of dietary fish oil supplementation in the disruption of barrier function.

Effect of kramecyne on the inflammatory response in lipopolysaccharide-stimulated peritoneal macrophages

Kramecyne is a new peroxide, it was isolated from Krameria cytisoides, methanol extract, and this plant was mostly found in North and South America. This compound showed potent anti-inflammatory activity; however, the mechanisms by which this compound exerts its anti-inflammatory effect are not well understood. In this study, we examined the effects of kramecyne on inflammatory responses in mouse lipopolysaccharide- (LPS-) induced peritoneal macrophages. Our findings indicate that kramecyne inhibits LPS-induced production of tumor necrosis factor (TNF-α) and interleukin- (IL-) 6. During the inflammatory process, levels of cyclooxygenase- (COX-) 2, nitric oxide synthase (iNOS), and nitric oxide (NO) increased in mouse peritoneal macrophages; however, kramecyne suppressed them significantly. These results provide novel insights into the anti-inflammatory actions and support its potential use in the treatment of inflammatory diseases.

Serum metabolic profiling study of hepatocellular carcinoma infected with hepatitis B or hepatitis C virus by using liquid chromatography-mass spectrometry

The objective of the present study was to explore the common and specific metabolic alterations of hepatocellular carcinoma (HCC) infected with hepatitis B virus (HBV) or hepatitis C virus (HCV). Serum profiling data revealed that the two HCC groups shared a mainly similar metabolic profile, providing a basis for investigating their common tumor pathogenesis mechanism and early diagnosis biomarkers. Arachidonic acid as a pro-inflammatory precursor increased significantly in the HCC group compared to the cirrhosis and healthy control. And the lysophosphatidylcholines (lysoPCs) with polyunsaturated fatty acid acyl chain with potent anti-inflammatory activity significantly decreased in the HCC and cirrhosis groups compared to those in the healthy control group, which may partly contribute to maintaining chronic inflammation and benefit the initiation and progression of the malignant hepatic tumor. The decreased ratios of polyunsaturated lysoPCs to saturated lysoPCs in HCC groups compared to chronic liver diseases infected with HBV or HCV and healthy control further demonstrated that a malignant liver tumor exerts profound influences independent of virus infection. Especially, serum endocannabinoids anandamide (AEA) and palmitylethanolamide (PEA) were found significantly elevated in HCC groups compared to healthy control, and in HCC with HCV compared to corresponding chronic liver diseases. AEA, PEA, or their combination showed better sensitivity, specificity, and the area under the curve for distinguishing HCC from chronic liver diseases, showing they are potential biomarkers to distinguish the HCC from cirrhosis infected with HCV.

Synthesis, evaluation and docking studies on 3-alkoxy-4-methanesulfonamido acetophenone derivatives as non ulcerogenic anti-inflammatory agents

A series of 3-alkoxy-4-methanesulfonamido acetophenone derivatives were synthesized and evaluated for their anti-inflammatory activity in carrageenan-induced rat paw edema model. The synthesized compounds were also investigated for their gastric ulcerogenic potential. The compounds 4a, 4c and 4d showed comparable anti-inflammatory activity to rofecoxib and indomethacin, the standard drugs taken in both studies and were also non ulcerogenic at the test doses. In silico (docking studies) were done to investigate the hypothetical binding mode of the target compounds to the cyclooxygenase isoenzyme (COX-2). A binding model has been proposed based on the docking studies. Selected physicochemical properties were calculated for theoretical ADME profiling of the compounds and excellent compliance was shown with Lipinski's rules.

Regulation of smooth muscle contraction by the epithelium: role of prostaglandins

As an analog to the endothelium situated next to the vascular smooth muscle, the epithelium is emerging as an important regulator of smooth muscle contraction in many vital organs/tissues by interacting with other cell types and releasing epithelium-derived factors, among which prostaglandins have been demonstrated to play a versatile role in governing smooth muscle contraction essential to the physiological and pathophysiological processes in a wide range of organ systems.

Ingestion of (n-3) fatty acids augments basal and platelet activating factor-induced permeability to dextran in the rat mesenteric vascular bed

Loss of intestinal barrier function and subsequent edema formation remains a serious clinical problem leading to hypoperfusion, anastomotic leakage, bacterial translocation, and inflammatory mediator liberation. The inflammatory mediator platelet activating factor (PAF) promotes eicosanoid-mediated edema formation and vasoconstriction. Fish oil-derived (n-3) fatty acids (FA) favor the production of less injurious eicosanoids but may also increase intestinal paracellular permeability. We hypothesized that dietary (n-3) FA would ameliorate PAF-induced vasoconstriction and enhance vascular leakage of dextran tracers. Rats were fed either an (n-3) FA-rich diet (EPA-rich diet; 4.0 g/kg EPA, 2.8 g/kg DHA) or a control diet (CON diet; 0.0 g/kg EPA and DHA) for 3 wk. Subsequently, isolated and perfused small intestines were stimulated with PAF and arterial pressure and the translocation of fluid and macromolecules from the vasculature to lumen and lymphatics were analyzed. In intestines of rats fed the EPA-rich diet, intestinal phospholipids contained up to 470% more EPA and DHA at the expense of arachidonic acid (AA). The PAF-induced increase in arterial pressure was not affected by the EPA-rich diet. However, PAF-induced fluid loss from the vascular perfusate was higher in intestines of rats fed the EPA-rich diet. This was accompanied by a greater basal loss of dextran from the vascular perfusate and a higher PAF-induced transfer of dextran from the vasculature to the lumen (P = 0.058) and lymphatics. Our data suggest that augmented intestinal barrier permeability to fluid and macromolecules is a possible side effect of (n-3) FA-rich diet supplementation.

Reduced tumour progression and angiogenesis in 1,2-dimethylhydrazine mice treated with NS-398 is associated with down-regulation of cyclooxygenase-2 and decreased beta-catenin nuclear localisation

Cyclooxygenase (COX)-2 is a key molecular target of colon cancer prevention. However, the mechanisms by which COX-2 inhibitors confer protective effects against tumour development are not completely understood. The aim of this study was to elucidate the effects of NS-398 in the 1,2-dimethylhydrazine (DMH) mouse model with respect to alteration in the expression of COX-2 and E-cadherin-catenin complex. Alterations in cell proliferation, apoptosis, and vascular density were investigated. NS-398 showed reduced COX-2 immunoreactivity in adenomas with a decrease in vascular density in non-dysplastic mucosa. Adenomas revealed increased E-cadherin and beta-catenin reactivity. NS-398 reduced the percentages of tumour cells with nuclear localisation of beta-catenin and cyclin D1. Bromodeoxyuridine (BrdUrd) index in adenomas was significantly higher in untreated animals. NS-398 resulted in significant increase in apoptosis in adenomas. Our results suggest a protective role of NS-398 on tumour development associated with reduced COX-2 expression, reduced vascular density and perturbation of beta-catenin signalling pathway.

Mitragynine inhibits the COX-2 mRNA expression and prostaglandin E₂ production induced by lipopolysaccharide in RAW264.7 macrophage cells

ETHNOPHARMACOLOGICAL RELEVANCE

[corrected] Mitragyna speciosa Korth (Rubiaceae) is one of the medicinal plants used traditionally to treat various types of diseases especially in Thailand and Malaysia. Its anti-inflammatory and analgesic properties in its crude form are well documented. In this study, the cellular mechanism involved in the anti-inflammatory effects of mitragynine, the major bioactive constituent, was investigated.

MATERIALS AND METHODS

The effects of mitragynine on the mRNA and protein expression of COX-1 and COX-2 and the production of prostaglandin E(2) (PGE(2)) were investigated in LPS-treated RAW264.7 macrophage cells. Quantitative RT-PCR was used to assess the mRNA expression of COX-1 and COX-2. Protein expression of COX-1 and COX-2 were assessed using Western blot analysis and the level of PGE(2) production was quantified using Parameter™ PGE(2) Assay (R&D Systems).

RESULTS

Mitragynine produced a significant inhibition on the mRNA expression of COX-2 induced by LPS, in a dose dependent manner and this was followed by the reduction of PGE(2) production. On the other hand, the effects of mitragynine on COX-1 mRNA expression were found to be insignificant as compared to the control cells. However, the effect of mitragynine on COX-1 protein expression is dependent on concentration, with higher concentration of mitragynine producing a further reduction of COX-1 expression in LPS-treated cells.

CONCLUSIONS

These findings suggest that mitragynine suppressed PGE(2) production by inhibiting COX-2 expression in LPS-stimulated RAW264.7 macrophage cells. Mitragynine may be useful for the treatment of inflammatory conditions.

Prebiotic treatment reduced preneoplastic lesions through the downregulation of toll like receptor 4 in a chemo-induced carcinogenic model

Germinated barley foodstuff contains prebiotics which are reported to have anti-cancerous effects in colorectal cancer model, but the detailed mechanism remains unclear. Recent studies revealed that the role of microbiota was strongly related to the regulation of incidence and progression of colorectal cancer. The aim of this study was to examine the anti-neoplastic mechanism by prebiotics. Azoxymethane treated F344 rats were used as the sporadic cancerous model. After azoxymethane injection, either a control or germinated barley foodstuff diet was administered to the rats for another 5 weeks, and the number of abberant crypt foci, toll like receptor 4, Kirsten rat sarcoma viral oncogene homolog, adenomatous polyposis coli tumor suppressor gene and cyclooxygenase 2 mRNA expression of colonic mucosa and cecal short chain fatty acids were examined. The germinated barley food stuff significantly attenuated the number of abberant crypt focis and the expression of toll like receptor 4 and cyclooxygenase 2 mRNA, compared to the control group. In addition, the cecal butyrate production in the germinated barley foodstuff group was significantly higher than that in the control. In conclusion, this prebiotic treatment for colorectal cancer may be useful without causing the adverse effects seen in either anti-cancer drugs or anti-inflammatory drugs.

Nutrition modulation of gastrointestinal toxicity related to cancer chemotherapy: from preclinical findings to clinical strategy

Chemotherapy-induced gut toxicity is a major dose-limiting toxicity for many anticancer drugs. Gastrointestinal (GI) complications compromise the efficacy of chemotherapy, promote overall malnutrition, aggravate cancer cachexia, and may contribute to worsened prognosis. The GI tract is an attractive target for nutrition modulation, owing to its direct exposure to the diet, participation in uptake and metabolism of nutrients, high rate of cell turnover, and plasticity to nutrition stimuli. Glutamine, ω-3 polyunsaturated fatty acids, and probiotics/prebiotics are therapeutic factors that potentially modulate GI toxicity related to cancer treatments. Preclinical and clinical evidence are reviewed to critically define plausible benefits of these factors and their potential development into adjuncts to cancer chemotherapy. Mechanisms underlying the action of these nutrients are being unraveled in the laboratory. Optimal strategies to translate these findings into clinical care still remain to be elucidated. Key questions that remain to be answered include the following: which nutrient or combination of nutrients is selected for which patient and chemotherapy regimen? What mechanisms are responsible for modulation, and how are nutrient(s) administered in a clinically optimal manner? Research exploring interactions between different nutrients in GI protection is ongoing and demands further understanding. How nutrition preparations given to chemotherapy-treated patients are formulated in terms of component selection and dose optimization should be carefully studied and justified.

Dietary aloin, aloesin, or aloe-gel exerts anti-inflammatory activity in a rat colitis model

AIMS

Aloe has been a very popular folk remedy for inflammation-related pathological conditions despite the lack of studies reporting its efficacy in vivo. The present study evaluated the anti-inflammatory effects of aloe components (aloin, aloesin and aloe-gel) known to be biologically active in the rat model of colitis.

MAIN METHODS

Male Sprague Dawley rats were fed experimental diets for 2 weeks before and during the induction of colitis. Drinking water containing 3% dextran sulfate sodium (DSS) was provided for 1 week to induce colitis. At the end of the experimental period, clinical and biochemical markers were compared.

KEY FINDINGS

Plasma leukotriene B(4) (LTB(4)) and tumor necrosis factor-α (TNF-α) concentrations were significantly decreased in all groups supplemented with aloe components compared to the colitis control group (p<0.05). Animals fed both a 0.1% and 0.5% aloesin supplemented diet showed colonic myeloperoxidase (MPO) activities which were decreased by 32.2% and 40.1%, respectively (p<0.05). Colonic mucosa TNF-α and interleukin-1ß (IL-1β) mRNA expressions were significantly reduced in all animals fed aloin, aloesin, or aloe-gel (p<0.05).

SIGNIFICANCE

Dietary supplementation of aloe components ameliorates intestinal inflammatory responses in a DSS-induced ulcerative colitis rat model. In particular, aloesin was the most potent inhibitor. Further studies are required for a more complete understanding of the specific mechanism of the action of these supplements.

Intestinal effects of lipopolysaccharide in rabbit are mediated by cyclooxygenase-2 through p38 mitogen activated protein kinase

The mediators of the pathophysiological symptoms of septic shock are not completely understood. The intracellular signalling mechanisms of lipopolysaccharide (LPS)-induced effects need further investigation. This study investigates (1) the role of COX-2 in the effect of LPS on (a) the KCl, acetylcholine and prostaglandin E₂-induced contractions of rabbit duodenum and (b) the oxidative stress status in plasma and intestine and (2) the relationship between p38 MAPK and COX-2 expression in rabbit duodenum. Rabbits were injected i.v. with either (1) saline, (2) LPS, (3) SB203580, a p38 MAPK inhibitor, (4) SB203580+LPS, (5) NS-398, a COX-2 inhibitor or (6) NS-398+LPS. Contractility studies were performed by suspending pieces of duodenum in an organ bath in the direction of longitudinal and circular smooth muscle fibres. The formation of products of oxidative damage to proteins (carbonyls) and lipids [malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA)] was quantified in intestinal tissue and plasma. The protein expression of COX-2 was measured by western blot. The KCl, acetylcholine and prostaglandin E₂-induced contractions decreased with LPS. In addition, LPS increased the levels of carbonyls and MDA+4-HDA in plasma and duodenum as well as COX-2 expression in duodenal tissue. All these effects were blocked by NS-398. The p38 MAPK inhibitor SB203580 blocked the effect of LPS on COX-2 expression. These results suggest that the effect of LPS on KCl, acetylcholine and prostaglandin E₂-induced contractions in the rabbit duodenum and oxidative stress might be mediated by an increase in COX-2 expression through the p38 MAPK pathway.

Roles of prostaglandin E2-EP1 receptor signaling in regulation of gastric motor activity and emptying

It is widely accepted that the inhibition of gastric motor activity as well as the maintenance of gastric mucosal blood flow and mucous secretion are important for the homeostasis of the gastric mucosa. The present study was performed to ascertain whether or not endogenous PGs, which can protect the stomach from noxious stimuli, affect gastric motor activity and emptying. The myoelectrical activity of rat gastric smooth muscle was increased at intragastric pressures of over 2 cmH(2)O. Replacement of intragastric physiological saline with 1 M NaCl solution significantly increased PGI(2) and PGE(2) in stomach and suppressed the myoelectrical activity under a pressure of 2 cmH(2)O by 70%. Indomethacin inhibited the suppression of myoelectrical activity by 1 M NaCl. The myoelectrical activity under a pressure of 2 cmH(2)O was suppressed by continuous infusion of a selective EP1 agonist (ONO-DI-004, 3-100 nmol·kg(-1)·min(-1)) into the gastric artery in a dose-dependent manner, but not by that of the PGI receptor agonist beraprost sodium (100 nmol·kg(-1)·min(-1)). Suppression of myoelectrical activity with 1 M NaCl was inhibited by continuous infusion of a selective EP1 antagonist (ONO-8711, 100 nmol·kg(-1)·min(-1)) into the gastric artery. Furthermore, gastric emptying was tested in EP1 knockout mice and their wild-type counterparts. Gastric emptying was strongly suppressed with intragastric 1 M NaCl in wild-type mice, but this 1 M NaCl-induced suppression was not seen in EP1 knockout mice. These results suggest that PGE(2)-EP1 signaling has crucial roles in suppression of myoelectrical activity of gastric smooth muscles and inhibition of gastric emptying and that EP1 is an obvious target for drugs that control gastric emptying.

The effect of genetic polymorphisms of cyclooxygenase 2 on acute pancreatitis in Turkey

OBJECTIVES

The aims of our study were to determine if polymorphisms in the cyclooxygenase 2 (COX-2) gene is associated with acute pancreatitis (AP) and to evaluate if inflammation risk is associated with specific COX-2 gene haplotypes containing these polymorphisms.

METHODS

The COX-2 genotypes for 7 polymorphisms (rs5275, rs2206593, rs4648262, rs4648261, rs2066826, rs5277, rs2745557) were determined using polymerase chain reaction-restriction fragment length polymorphism analysis in 103 patients with AP and 92 healthy controls.

RESULTS

Except for rs5275, the frequencies of COX-2 polymorphisms were both similar in patients with mild or severe pancreatitis, so were in pancreatitis patients and in controls. Only rs5275 was statistically significantly associated with AP risk. The association was seen with rs5275 (P = 0.03); specifically, patients carrying the TT genotype in comparison with patients carrying the CC genotype had a significantly lower risk of disease (odds ratio, 1.88; 95% confidence interval, 1.06-3.34). Haplotypes with nucleotide T at the -18491961 position (rs5275) and A at the 184915627 position (rs4648261) of COX-2 promoter seem to increase susceptibility (odds ratio, 2.46; 95% confidence interval, 1.15-5.29; P = 0.02).

CONCLUSIONS

These findings suggest that the rs5275 polymorphism in the 3'-untranslated region of the COX-2 gene may be used as 1 marker for defining the risk of AP.

Chemopreventive activities of etodolac and oxyphenbutazone against mouse skin carcinogenesis

Previous cancer chemoprevention studies have demonstrated that the non-steroidal anti-inflammatory drugs (NSAIDs) can be effective in suppressing the development of various human malignancies. Recently we identified the possible anti-tumor promoting potentials of 14 new NSAIDs in the Epstein-Barr virus early antigen activation assay induced by 12-O-tetradecanoylphorbol-13-acetate (TPA). In this study we report the inhibition of 7,12-dimethylbenz (a) anthracene (DMBA) induced two-stage mouse skin carcinogenesis by etodolac (ETD), one of the most potent NSAIDs identified in our in vitro cancer chemopreventive screening of this group of drugs. Topical administration of ETD at a very low dose of 85 nmol showed a significant decrease in both tumor incidence and burden. This effect is also accompanied by a delay in the tumor latency period. Since ETD showed potent chemopreventive activity in both in vitro and in vivo studies, it warrants prompt consideration for trial in humans as a potential cancer chemopreventive agent. We also investigated oxyphenbutazone (OPB) another commonly used NSAID for its cancer chemopreventive effect on peroxynitrite (PN) induced-TPA promoted skin tumors in the mouse. Following tumor initiation with 390 nmol of PN, the skin tumor promotion with 1.7 nmol of TPA was significantly inhibited by oral administration of 0.0025% OPB. The results demonstrate that OPB is a potent cancer chemopreventive agent in the highly sensitive in vivo mouse test model we used.