Current approach to hepatobiliary manifestations in inflammatory bowel disease.

Inflammatory bowel disease (IBD), including the two main subtypes - Crohn's disease (CD) and ulcerative colitis (UC) - has a wide range of extra-intestinal manifestations (EIMs) that are major causes of morbidity and disability. The following EIMs can be classified as IBD-associated: mucocutaneous, ocular, pulmonary, renal, genitourinary, hematological, neurological, psychiatric, cardiac and hepatobiliary. The latter include primary sclerosing cholangitis (PSC), cholelithiasis, IgG4 associated cholangiopathy (IAC), autoimmune hepatitis (AIH), non-alcoholic fatty liver disease (NAFLD), hepatitis B and C, and drug-induced hepatotoxicity. The aim of this review is to examine our current knowledge of IBD - associated hepatobiliary EIMs and their treatment.

Nrf2 transcriptional activity in the mouse affects the physiological response to tribromoethanol.

Up to date, there is no information on the influence of 2,2,2-tribromoethanol (TBE; Avertin), a commonly used anaesthetic, on mice with impaired antioxidant capacity. We aimed to analyse the effect of a single dose of Avertin on anaesthesia duration time, inflammatory response, oxidative stress and collagen deposition in the large intestine of Nrf2 transcriptional knockout mice (tNrf2-/-). The studies were performed on six-month-old female mice Nrf2+/+ and tNrf2-/- randomly assigned to Avertin (250 mg/kg b.w. single i.p. injection) or vehicle group. We observed a 2-fold increase in anaesthesia time and longer recovery time (p = 0.015) in tNrf2-/- in comparison to Nrf2+/+. However, no hepato- or nephrotoxicity was detected. Interestingly, we found severe changes in colon morphology of untreated tNrf2-/- mice associated with colon shortening (p = 0.02) and thickening (p = 0.015). Avertin treatment caused colon damage manifested with epithelial layer damage and goblet depletion in Nrf2+/+ mice but not in tNrf2-/- individuals. Additionally, Avertin did not induce oxidative stress in colon tissue, but it increased leukocyte infiltration in Nrf2+/+ mice (p = 0.02). Immunofluorescent staining also revealed enhanced deposition of collagen I and collagen III in the colon of untreated tNrf2-/- mice. Avertin contributed to increased deposition of collagen I in Nrf2+/+ mice but reduced deposition of collagen I and III in tNrf2-/- individuals. In conclusion, tNrf2-/- respond to Avertin with prolonged anaesthesia that is not associated with acute toxicity, inflammatory reaction or enhanced oxidative stress. Avertin does not impair intestine morphology in tNrf2-/- mice but can normalise the enhanced fibrosis.

Spent hops (Humulus Lupulus L.) extract as modulator of the inflammatory response in lipopolysaccharide stimulated RAW 264.7 macrophages.

Macrophages play important roles in acute and chronic inflammation. Upon their activation, they secrete a variety of mediators, including eicosanoids, nitric oxide and cytokines, which play different roles in the stimulation and resolution of inflammatory processes. There is a continuous search for selective modulators of these processes. Natural polyphenols and polyphenol-rich extracts have been found to possess preventive and therapeutic potential, including by their anti-inflammatory effects. In this study, the inhibition of the formation of inflammatory mediators by the spent hops extract (SHE), a polyphenol-rich extract from Humulus Lupulus L., was examined using lipopolysaccharide (LPS)- activated murine macrophages (RAW 264.7). The SHE suppressed inter alia the interleukin-6 (IL-6) mRNA expression to 32% in LPS-activated macrophages and to 61% at a protein level (at 25 µg/mL). SHE reduced both the cyclooxygenase-2 (COX-2) mRNA expression to 47% and their protein expression to 32%. Not only did SHE inhibit the IL-6 and COX-2 levels but also decreased both inducible nitric oxide synthase (iNOS) protein expression to 2% at 25 µg/mL and nitric oxide (NO) production for all tested concentrations. The inhibited expression of these inflammatory molecules was likely caused by the reduced activity of nuclear factor-κB (NF-κB). Both mRNA and protein expression of NF-κB was decreased to 38% and 42%, respectively. These results provide the first evidence that SHE decreases the expression of proinflammatory cytokines and inflammatory mediators, which merits further studies to investigate the potential of SHE as anti-inflammatory preparation.

Japanese quince (Chaenomeles japonica) leaf phenol extract as modulator of the inflammatory response in lipopolysaccharide-triggered murine macrophage RAW 264.7 cells.

In the present study we investigated the anti-inflammatory activity of Japanese quince leaf polyphenol-rich extract (JQLPE) in lipopolysaccharide (LPS)-activated murine macrophages (RAW 264.7). The Q-PCR analysis revealed that JQLPE decreased Nfkb1, Ptgs2, and Il1b expression at the mRNA level by 80%, 50% and 48%, respectively. Similarly, JQLPE significantly attenuated expression of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), interleukin-1beta (IL-1ß), IL-6 and tumor necrosis factor alpha (TNF-α) (by 60%, 50%, 67%, 37% and 36%, respectively) at the protein level and nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW264.7. Western blot also showed that the expression of nuclear factor kappaB (NF-κB) p65 and p-NF-κB p65 was down-regulated after JQLPE treatment. These results provide the first evidence that JQLPE decreases the expression of pro-inflammatory cytokines (IL-1ß, IL-6, TNF-α), inflammatory mediators (COX-2, iNOS) and both NF-κB p65 and p-NF-κB p65 in LPS-stimulated RAW264.7 cells, which may suggest its anti-inflammatory activity.

Evaluation of the effect of liposomes loaded with chlorogenic acid in treatment of 2,4,6-trinitrobenzenesulfonic acid-induced murine colitis.

Crohn's Disease (CD), one of the types of inflammatory bowel disease, poses a significant challenge to modern healthcare. This condition severely impacts patients' quality of life, and its incidence is continuously rising. Despite constant research, current treatment options are limited and largely unsuccessful and result in serious side effects, therefore new therapy alternatives are needed. Liposomal formulation provides a new hope for disease management. In our study, we characterized the anti-inflammatory activity of mesalazine (5-ASA) and chlorogenic acid (CGA) encapsulated in liposomal formulation in the animal model of CD. Liposomes were obtained by thin film hydration method and characterized in terms of suspension stability and particle size and distribution. Colitis was induced in mice by intracolonic (i.c.) administration of 2,4,6-trinitrobenzenesulfonic acid (TNBS). The effect of treatment with liposomal suspensions of 5-ASA and CGA was evaluated macroscopically and by measuring myeloperoxidase (MPO) activity. We observed that liposome-encapsulated 5-ASA (5 mg/kg), but not CGA (20 mg/kg) attenuated colitis as evidenced by a decreased macroscopic and microscopic scores. It may be hypothesized that the composition of liposomal lipid bilayer as well as the switch in macrophage populations leading to unfavorable accumulation of anti-inflammatory agents in the cells may underly the efficiency of obtained liposomes and need to be taken into consideration in further studies on drug delivery.

The place of tachykinin NK2 receptor antagonists in the treatment diarrhea-predominant irritable bowel syndrome.

Tachykinins act as neurotransmitters and neuromodulators in the central and peripheral nervous system. Preclinical studies and clinical trials showed that inhibition of the tachykinin receptors, mainly NK2 may constitute a novel attractive option in the treatment of irritable bowel syndrome (IBS). In this review, we focused on the role of tachykinins in physiology and pathophysiology of gastrointestinal (GI) tract. Moreover, we summed up recent data on tachykinin receptor antagonists in the therapy of IBS. Ibodutant is a novel drug with an interesting pharmacological profile, which exerted efficacy in women with diarrhea-predominant IBS (IBS-D) in phase II clinical trials. The promising results were not replicable and confirmed in phase III of clinical trials. Ibodutant is not ready to be introduced in the pharmaceutical market and further studies on alternative NK2 antagonist are needed to make NK2 antagonists useful tools in IBS-D treatment.

Sleep disturbance and disease activity in adult patients with inflammatory bowel diseases.

The aim of the study was to identify whether poor quality of sleep is connected to inflammatory bowel disease (IBD) and if so, whether sleep disturbances are related to disease activity. Prospective, observational cohort study was performed. In all enrolled adult patients, the disease activity was assessed by using Crohn's Disease Activity Index (CDAI) for Crohn's disease (CD) and Partial Mayo Score for ulcerative colitis (UC), respectively. All patients were also asked to respond to a questionnaire to define Pittsburgh Quality Sleep Index (PSQI). Sixty-five patients were enrolled in our study: n = 30 with CD and n = 35 with UC. The poor sleep was noted in 78% (40/51) patients with clinically exacerbation and in 35% (5/14) patients in remission (P = 0.002; OR 6.5, 95% confidence interval, 1.8 - 23.6). A global PSQI score of 5 points yielded a sensitivity of 84%, a specificity of 39%, and a positive predictive value of 89% for discriminating participants with exacerbation of IBD from those in clinical remission; PSQI higher than 6 indicates the exacerbation of IBD with 77% sensitivity and 62% specificity. The poorest sleep quality was reported in IBD patients with severe exacerbations (9.1 ± 2.9). Sleep disturbance was confirmed in adult IBD patients, both in CD and UC. Confirmation of the relationship between sleep abnormalities and IBD may show the new pathway in pathophysiology, course and treatment of IBD.

Novel peptide inhibitor of dipeptidyl peptidase IV (Tyr-Pro-D-Ala-NH2) with anti-inflammatory activity in the mouse models of colitis.

Protease inhibition has become a new possible approach in the inflammatory bowel disease (IBD) therapy. A serine exopeptidase, dipeptidyl peptidase IV (DPP IV) is responsible for inactivation of incretin hormone, glucagon-like peptide 2 (GLP-2), a potent stimulator of intestinal epithelium regeneration and growth. Recently we showed that the novel peptide analog of endomorphin-2, EMDB-1 (Tyr-Pro-D-ClPhe-Phe-NH2) is a potent blocker of DPP IV and exhibits an anti-inflammatory activity in vivo. The aim of this study was to design, synthesize and characterize the therapeutic activity and mechanism of action of a series of novel EMDB-1 analogs. The inhibitory potential of all peptides was evaluated using the fluorometric screening assay employing Gly-Pro-Aminomethylcoumarin (AMC) to measure DPP IV activity. Consequently, one compound, namely DI-1 was selected and its therapeutic activity evaluated using mouse models of experimental colitis (induced by TNBS and DSS). Macro- and microscopic score, ulcer score, colonic wall thickness as well as myeloperoxidase activity were measured. We showed that DI-1 blocks DPP IV in vitro (IC50 = 0.76 ± 0.04 nM) and attenuates acute, semichronic and relapsing TNBS- as well as DSS-induced colitis in mice after topical administration. Its anti-inflammatory action is associated with the increase of colonic GLP-2 but not GLP2 receptor or DPP IV expression. Our results validate DPP IV as a pharmacological target for the anti-IBD drugs and its inhibitors, such as DI-1, have the potential to become valuable anti-inflammatory therapeutics.

Pharmacological and dietary factors in prevention of colorectal cancer.

Colorectal cancer (CRC) is the third most prevalent neoplasm worldwide and fourth most frequent reason of cancer-related death throughout the world. About 70% of malignant tumors are related to lifestyle and environmental factors, and better knowledge of their significance might reduce the prevalence of CRC. The cyclooxygenase-2 (COX-2) inhibitory and other direct and indirect pathways of aspirin are translated to inhibition proliferation and enhanced apoptosis of cancer cells. Many studies showed the benefits of aspirin in reducing the risk of CRC development, cancer-related mortality and adenoma prevalence rate in general population, but not in high risk populations. The role of sulindac in CRC prevention is uncertain and the use of this drug is rather uncommon. Celecoxib - COX-2 selective inhibitor- showed efficacy in decreasing of colon adenoma recurrence only in some studies. The protective role of microelements is controversial. The beneficial effects of supplementation of selenium, calcium, folic acid, methionine, antioxidant supplements and probiotics are still not certain. A high energy diet consisting of red meat, animal fat, highly processed foods and unsaturated fats increases the risk of CRC. Carcinogenic role of fat and cholesterol depends on increased production of primary bile acids. The importance of milk and dairy products in CRC prevention is controversial. Fruits, vegetables and grain are considered to have protective effects against adenoma and CRC. Excessive alcohol consumption, smoking, physical inactivity are considered as important CRC risk factors. This article briefly summarizes current state of knowledge about the role of pharmacological and dietary prevention of colorectal cancer. Moreover, it indicates that despite many studies some aspects of this issue are not clear and require future studies.

The effect of long-term melatonin supplementation on psychosomatic disorders in postmenopausal women.

Different psychosomatic disorders are observed in postmenopausal women. The decrease of estrogen production is believed to be the main cause of their severity. It is nowadays evident that the decreased melatonin release in women at this age who suffer from postmenopausal disorders might also contribute to the severity of the symptoms. The aim of the study was to evaluate the effect of melatonin supplementation on female hormones release and the alteration in climacteric symptoms. The study included 60 postmenopausal women, aged 51 - 64 years, who were randomly allotted into two equal groups. Group I was recommended placebo (2 x 1 tablet) and Group II - melatonin (3 mg in the morning and 5 mg at bedtime) for 12 months. Serum levels of 17ß-estradiol, follicle-stimulating hormone (FSH), melatonin and urinary 6-sulfatoxymelatonin (aMT6s) excretion as well as Kupperman Index (KI) and body mass index (BMI) were determined before the start and at 12 months after placebo or melatonin administration. In Group I only the value of KI slightly decreased (28.4 ± 2.9 versus 25.6 ± 3.8 points, P = 0,0619). In Group II - KI decreased from 29.1 ± 2.9 to 19.7 ± 3.1 points (P < 0.001) and BMI from 30.9 ± 2.9 to 28.1 ± 2.3 kg/m2 (P < 0.05). Melatonin supplementation failed to change significantly the serum concentration of female reproductive hormones 17ß-estradiol and FSH. We conclude that melatonin supplementation therapy exerts a positive effect on psychosomatic symptoms in postmenopausal women and can be recommended as the useful adjuvant therapeutic option in treatment of these disorders.

Alterations in the gut barrier and involvement of Toll-like receptor 4 in murine postoperative ileus.

BACKGROUND: The changes in the gut barrier (GB) and associated mechanisms in postoperative ileus (POI) are still unclear. Toll-like receptor 4 (TLR4) is involved in inflammation, which may cause GB dysfunction and POI. Here, the roles of the GB in POI in relation to TLR4-dependent signaling pathways were explored. METHODS: POI was induced by small bowel manipulation in wild-type (WT) and TLR4-knockout (TLR4-/-) mice. Twenty-four hours after manipulation, indices of gastrointestinal (GI) transit, GB structure and function, inflammation, and related signaling pathways were analyzed. KEY RESULTS: Normal GI motility and GB function were not affected by TLR4 knockout. Compared with WT POI mice, TLR4-/-POI mice showed milder GI transit retardation, GB dysfunction, and inflammatory responses. In WT mice, GB disorder was characterized by colonic goblet cells depletion, increased gut claudin-2 expression, and decreased CD4+/CD8+ ratios in intestinal Peyer's patches. Green fluorescent protein-tagged Escherichia coli in the gut was detected in plasma and extraintestinal organs, followed with increased plasma lipopolysaccharide. These changes displayed in WT POI mice were less severe in TLR4-/-POI mice. Furthermore, the mRNA and protein expression of interleukin-6, monocyte chemotactic protein-1, pp38 and pJNK in the intestine, and TNF-α level in plasma were significantly increased in WT, but not TLR4-/-POI mice. CONCLUSIONS & INFERENCES: These results indicate that GB is impaired in the experimental POI, with inflammation being involved in this pathological process. TLR4 deficiency alleviated GB dysfunction and suppressed inflammation by disrupting the activation of mitogen-activated protein kinase signaling pathways, thereby ameliorating POI.

High activity of the endogenous opioid system and acute but not chronic stress influence experimental colitis development in mice.

Exposition to environmental factors is one of the major underlying causes in inflammatory bowel diseases (IBD), with several endogenous systems involved. Our aim was to characterize the impact of stress on the colitis development in relation to the endogenous opioid system (EOS) activity in mice. A unique mouse model of high and low activity of EOS (namely high (HA)/low (LA) stress-induced analgesia) was employed. Mice were bred using bidirectional selection and classified as HA or LA line based on the measurement of analgesia. Colitis was induced by instillation of trinitrobenzenesulfonic acid in 30% EtOH/0.9% NaCl. After 4 days, the macroscopic score was assessed and samples for molecular and histological studies were collected. To evaluate the influence of stress on colitis development, chronic mild stress (exposure to stress stimuli for 2 and 5 weeks) and acute stress (short restraint over 3 days) were applied before colitis induction. We observed a difference in the colitis development between non-stressed HA and LA mice, as indicated by macroscopic and ulcer scores. Acute stress improved colitis in HA mice but did not change the inflammation score in LA line as compared to respective non-stressed mice. Chronic mild stress had no influence on colitis in either of mouse lines. Our study supports the hypothesis that the activity of EOS may be crucial in IBD development. We also evidence that acute, but not chronic stress influenced IBD exacerbation, depending on EOS function.

Prosecretory effect of loperamide in ileal and colonic mucosae of mice displaying high or low swim stress-induced analgesia associated with high and low endogenous opioid system activity.

BACKGROUND: Irritable bowel syndrome (IBS) is characterized by abdominal pain, bloating, and changes in bowel habit. The aim of this study was to characterize the effect of loperamide hydrochloride (LOP) and naloxone hydrochloride (NLX), an opioid agonist and antagonist, respectively, on electrolyte equilibrium in ileal and colonic mucosae and to estimate the possible influence of divergent activity of the endogenous opioid system (EOS) on IBS therapy. METHODS: Two mouse lines bidirectionally selected for high (HA) and low (LA) swim stress-induced analgesia associated with high and low EOS activity were used in this study. To assess the effect of LOP and NLX on HA/LA lines in vivo, we used the castor oil-induced diarrhea model. Changes in electrolyte equilibrium were determined on the basis of short-circuit current (ΔIsc ) in isolated mouse ileum and colon exposed to LOP and NLX and stimulated by forskolin (FSK), veratridine (VER), and bethanechol (BET). KEY RESULTS: In vivo, we found that LOP significantly prolonged time to appearance of diarrhea in HA and LA lines. In vitro, LOP and NLX increased ΔIsc in FSK- and VER-stimulated colonic tissue, respectively, in HA line. In the ileum, LOP increased ΔIsc in FSK- and VER-stimulated tissue and decreased ΔIsc in BET-stimulated tissues in HA line. CONCLUSIONS & INFERENCES: Individual differences in EOS activity may play a crucial role in the response to the IBS-D therapy, thus some patients may be at an increased risk of side effects such as constipation or diarrhea.

FABP4 blocker attenuates colonic hypomotility and modulates white adipose tissue-derived hormone levels in mouse models mimicking constipation-predominant IBS.

BACKGROUND: The role of fatty acid binding protein 4 (FABP4) in lower gastrointestinal (GI) motility is unknown. We aimed to verify the effect of inhibition of FABP4 on GI transit in vivo, and to determine the expression of FABP4 in mouse and human tissues. METHODS: Fatty acid binding protein 4 inhibitor, BMS309403, was administered acutely or chronically for 6 and 13 consecutive days and its effect on GI transit was assessed in physiological conditions and in loperamide-induced constipation. Intracellular recordings were made to examine the effects of BMS309403 on colonic excitatory and inhibitory junction potentials. Abdominal pain was evaluated using behavioral pain response. Localization and expression of selected adipokines were determined in the mouse colon and serum using immunohistochemistry and Enzyme-Linked ImmunoSorbent Assay respectively. mRNA expression of FABP4 and selected adipokines in colonic and serum samples from irritable bowel syndrome (IBS) patients and control group were assessed. KEY RESULTS: Acute injection of BMS309403 significantly increased GI motility and reversed inhibitory effect of loperamide. BMS309403 did not change colonic membrane potentials. Chronic treatment with BMS309403 increased the number of pain-induced behaviors. In the mouse serum, level of resistin was significantly decreased after acute administration; no changes in adiponectin level were detected. In the human serum, level of adiponectin and resistin, but not of FABP4, were significantly elevated in patients with constipation-IBS (IBS-C). FABP4 mRNA expression was significantly downregulated in the human colon in IBS-C. CONCLUSIONS AND INFERENCES: Fatty acid binding protein 4 may be involved in IBS pathogenesis and become a novel target in the treatment of constipation-related diseases.

Modulation of the endocannabinoid system by the fatty acid amide hydrolase, monoacylglycerol and diacylglycerol lipase inhibitors as an attractive target for secretory diarrhoea therapy.

Secretory diarrhoea is a leading cause of mortality and morbidity worldwide. Our aim was to characterize the effect of inhibition of selected enzymes involved in the synthesis or degradation of endocannabinoids on electrolyte equilibrium in the mouse colonic tissue. The aim of this study was to evaluate the effects of PF-3845, JZL-184 and RHC-80267, as inhibitors of fatty acid amide hydrolase (FAAH), monoacylglycerol (MAGL) and diacylglycerol lipase (DAGL), respectively on epithelial ion transport in isolated mouse colon stimulated by forskolin (FSK), veratridine (VER) and bethanechol (BET). Next, colonic tissue was co-incubated with selected inhibitors and cannabinoid receptor antagonists: AM 251 and AM 630 (CB1 and CB2 antagonists, respectively). We found that PF-3845 induced antisecretory effect in FSK-stimulated colonic tissue (P < 0.01), which was significantly reversed by AM 251 (P < 0.001) and AM 630 (P < 0.01). JZL-184 significantly reduced ΔIsc (P < 0.05) in FSK-stimulated conditions and co-incubation with AM 630, but not AM 251 reversed this effect when compared to JZL-184 alone (P < 0.05). After addition of PF-3845 and JZL-184 to colon tissue stimulated by VER, we did not observe any significant effect on ΔIsc. PF-3845, JZL-184 or RHC-80267 were without any statistically significant effect on BET-evoked ion transport when compared to control. Our findings showed that indirect modulation of the endocannabinoid system could be an attractive target for novel effective treatment of secretory diarrhoea, which is devoid of side effects on the central nervous system caused by direct administration of cannabinoid receptor agonists.

Targeting fatty acid amide hydrolase and transient receptor potential vanilloid-1 simultaneously to modulate colonic motility and visceral sensation in the mouse: A pharmacological intervention with N-arachidonoyl-serotonin (AA-5-HT).

BACKGROUND: Endocannabinoid anandamide (AEA) inhibits intestinal motility and visceral pain, but it may also be proalgesic through transient receptor potential vanilloid-1 (TRPV1). AEA is degraded by fatty acid amide hydrolase (FAAH). This study explored whether dual inhibition of FAAH and TRPV1 reduces diarrhea and abdominal pain. METHODS: Immunostaining was performed on myenteric plexus of the mouse colon. The effects of the dual FAAH/TRPV1 inhibitor AA-5-HT on electrically induced contractility, excitatory junction potential (EJP) and fast (f) and slow (s) inhibitory junction potentials (IJP) in the mouse colon, colonic propulsion and visceromotor response (VMR) to rectal distension were studied. The colonic levels of endocannabinoids and fatty acid amides were measured. KEY RESULTS: CB1-positive neurons exhibited TRPV1; only some TRPV1 positive neurons did not express CB1. CB1 and FAAH did not colocalize. AA-5-HT (100 nM-10 µM) decreased colonic contractility by ~60%; this effect was abolished by TRPV1 antagonist 5'-IRTX, but not by CB1 antagonist, SR141716. AA-5-HT (1 µM-10 µM) inhibited EJP by ~30% and IJPs by ~50%. The effects of AA-5-HT on junction potentials were reversed by SR141716 and 5`-IRTX. AA-5-HT (20 mg/kg; i.p.) inhibited colonic propulsion by ~30%; SR141716 but not 5`-IRTX reversed this effect. AA-5-HT decreased VMR by ~50%-60%; these effects were not blocked by SR141716 or 5`-IRTX. AA-5-HT increased AEA in the colon. CONCLUSIONS AND INFERENCES: The effects of AA-5-HT on visceral sensation and colonic motility are differentially mediated by CB1, TRPV1 and non-CB1/TRPV1 mechanisms, possibly reflecting the distinct neuromodulatory roles of endocannabinoid and endovanilloid FAAH substrates in the mouse intestine.

Highly selective CB2 receptor agonist A836339 has gastroprotective effect on experimentally induced gastric ulcers in mice.

Cannabinoid type 2 (CB2) receptors are distributed in central and peripheral tissues, including immunocytes and the gastrointestinal (GI) tract, suggesting that CB2 receptor agonists represent potential therapeutics in GI inflammatory states. In this study, we investigated the effect of highly selective CB2 agonist, A836339, on the development of gastric lesions. We used two models of gastric ulcer (GU) induced by ethanol (EtOH) and diclofenac. To confirm the involvement of CB2 receptors, a selective CB2 antagonist, AM630 was used. Clinical parameters for gastroprotection were assessed based on inhibition of the gastric lesion area. To investigate the anti-inflammatory effect of A836339, the expression of TNF-α and IL-1ß was assessed. To establish the mechanism of gastroprotective action, catalase (CAT), superoxide dismutase (SOD) activity and H2O2 and glutathione (GSH) levels were measured. Moreover, expression of CB2 and cyclooxygenase-2 (COX-2) was characterized using immunohistochemistry (IHC). A836339 reduced ulcer index in a dose-dependent manner in both EtOH- and diclofenac-induced GU models. This effect was reversed by the CB2 antagonist AM630. Administration of A836339 reduced TNF-α and IL-1ß levels in gastric tissue. Furthermore, A836339 exhibited potent anti-oxidant activity, as demonstrated by reduced H2O2 levels and increased CAT and SOD activities. IHC studies revealed a co-localization of CB2 receptors and COX-2 in the gastric tissue. Activation of CB2 receptors exhibited gastroprotective effect through enhancement of anti-oxidative pathways in the stomach. Activation of CB2 receptors may thus become a novel therapeutic approach in the treatment of GU.

Systemic Administration of Sialorphin Attenuates Experimental Colitis in Mice via Interaction With Mu and Kappa Opioid Receptors.

BACKGROUND AND AIMS: Pharmacological treatment and/or maintenance of remission in inflammatory bowel disease [IBD] is currently one of the biggest challenges in the field of gastroenterology. Here we aimed to assess the anti-inflammatory effect and the mechanism of action of sialorphin, the natural blocker of the endogenous opioid peptide-degrading enzymes neprilysin [NEP] and aminopeptidase N [APN], in mouse models of IBD and the changes in the expression of these enzymes in IBD patients. METHODS: We used two models of experimental colitis in mice [2,4,6-trinitrobenzene sulphonic acid [TNBS]- and dextran sulphate sodium [DSS]-induced]. Macroscopic score, ulcer score, colonic wall thickness, and myeloperoxidase [MPO] activity were recorded. Additionally, we measured the expression of NEP and APN in the colon of IBD patients and healthy controls. RESULTS: We showed that sialorphin attenuated acute, semichronic, and relapsing TNBS-induced colitis in mice after systemic administration, and its anti-inflammatory action is associated with mu and kappa opioid receptors. CONCLUSIONS: We show that indirect stimulation of opioid receptors by the blockade of NEP and APN is a promising pharmacological strategy for the treatment of IBD, and may become of greater importance than the use of classical opioid agonists.

Cannabinoids as gastrointestinal anti-inflammatory drugs.

In this mini-review, we focus on the potential of the endocannabinoid system as a target for novel therapies to treat gastrointestinal (GI) inflammation. We discuss the organization of the endocannabinoid signaling and present possible pharmacological sites in the endocannabinoid system. We also refer to recent clinical findings in the field. Finally, we point at the potential use of cannabinoids at low, non-psychoactive doses to counteract non-inflammatory pathological events in the GI tract, like chemotherapy-induced diarrhea, as evidenced by Abalo et al. in the rat model.

G protein-coupled estrogen receptor and estrogen receptor ligands regulate colonic motility and visceral pain.

BACKGROUND: Diarrhea-predominant irritable bowel syndrome (IBS-D) is a functional gastrointestinal (GI) disorder, which occurs more frequently in women than men. The aim of our study was to determine the role of activation of classical estrogen receptors (ER) and novel membrane receptor, G protein-coupled estrogen receptor (GPER) in human and mouse tissue and to assess the possible cross talk between these receptors in the GI tract. METHODS: Immunohistochemistry was used to determine the expression of GPER in human and mouse intestines. The effect of G-1, a GPER selective agonist, and estradiol, a non-selective ER agonist, on muscle contractility was characterized in isolated preparations of the human and mouse colon. To characterize the effect of G-1 and estradiol in vivo, colonic bead expulsion test was performed. G-1 and estradiol activity on the visceral pain signaling was assessed in the mustard oil-induced abdominal pain model. KEY RESULTS: GPER is expressed in the human colon and in the mouse colon and ileum. G-1 and estradiol inhibited muscle contractility in vitro in human and mouse colon. G-1 or estradiol administered intravenously at the dose of 20 mg/kg significantly prolonged the time to bead expulsion in females. Moreover, G-1 prolonged the time to bead expulsion and inhibited GI hypermotility in both genders. The injection of G-1 or estradiol resulted in a significant reduction in the number of pain-induced behaviors in mice. CONCLUSIONS AND INFERENCES: GPER and ER receptors are involved in the regulation of GI motility and visceral pain. Both may thus constitute an important pharmacological target in the IBS-D therapy.