Encenicline, an α7 Nicotinic Acetylcholine Receptor Partial Agonist, Reduces Immune Cell Infiltration in the Colon and Improves Experimental Colitis in Mice.

The α7 pentamer nicotinic acetylcholine receptors (nAChRs) are a target in transduction of anti-inflammatory signals from the central nervous system to the gastrointestinal (GI) tract. The aim of this study was to investigate the anti-inflammatory action of the novel α7 nAChR partial agonist encenicline and to determine the mechanism underlying its activity. Anti-inflammatory activity of encenicline was evaluated using trinitrobenzenesulfonic acid (TNBS)- and dextran sulfate sodium (DSS)-induced models of colitis. Macroscopic score, ulcer score, colon length and thickness, as well as myeloperoxidase (MPO) activity were recorded. Immunohistochemistry (IHC) was used to measure the infiltration of immune cells in the colon. Furthermore, we employed flow cytometry to determine the effect of encenicline on frequencies of FoxP3(+) and interleukin (IL)-17A(+) T cells in the mouse colon. Encenicline attenuated TNBS- and DSS-induced colitis in mice via α7 nAChRs, as indicated by significantly reduced macroscopic parameters and MPO activity. Treatment with encenicline significantly reduced the infiltration of macrophages, neutrophils, and B cells in the colon of TNBS-treated animals, as indicated by IHC. In the TNBS model encenicline reduced the frequency of FoxP3(+) IL-17A(+) T cells in the colon. In the DSS-model treatment encenicline increased the frequency of FoxP3(+) T cells and reduced IL-17A(+) T cells. Stimulation of α7 nAChR with partial agonist encenicline alleviates colitis via alteration of the number and/or activation status of the immune cells in the gut, emphasizing a potential role of α7 nAChRs as a target for anticolitic drugs.

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.

Transient receptor potential vanilloid 4 inhibits mouse colonic motility by activating NO-dependent enteric neurotransmission.

UNLABELLED: Recent studies implicate TRPV4 receptors in visceral pain signaling and intestinal inflammation. Our aim was to evaluate the role of TRPV4 in the control of gastrointestinal (GI) motility and to establish the underlying mechanisms. We used immunohistochemistry and PCR to study TRPV4 expression in the GI tract. The effect of TRPV4 activation on GI motility was characterized using in vitro and in vivo motility assays. Calcium and nitric oxide (NO) imaging were performed to study the intracellular signaling pathways. Finally, TRPV4 expression was examined in the colon of healthy human subjects. We demonstrated that TRPV4 can be found on myenteric neurons of the colon and is co-localized with NO synthase (NOS-1). In vitro, the TRPV4 agonist GSK1016790A reduced colonic contractility and increased inhibitory neurotransmission. In vivo, TRPV4 activation slowed GI motility and reduced stool production in mouse models mimicking pathophysiological conditions. We also showed that TRPV4 activation inhibited GI motility by reducing NO-dependent Ca(2+) release from enteric neurons. In conclusion, TRPV4 is involved in the regulation of GI motility in health and disease. KEY MESSAGES: • Recent studies implicate TRPV4 in pain signaling and intestinal inflammation. • Our aim was to characterize the role of TRPV4 in the control of GI motility. • We found that TRPV4 activation reduced colonic contractility. • Our studies also showed altered TRPV4 mRNA expression in IBS-C patients. • TRPV4 may be a novel pharmacological target in functional GI diseases.

Polyphenol extract from evening primrose pomace alleviates experimental colitis after intracolonic and oral administration in mice.

Oenothera paradoxa (EP) preparations are commonly used in folk medicine to treat skin diseases, neuralgia, and gastrointestinal (GI) disorders. Several reports suggested that EP preparations exhibit potent anti-inflammatory and antioxidant activities both in vitro and in vivo. Here, we aimed to characterize the action of EP pomace polyphenol extract in mouse model of colitis. We analyzed the composition of EP pomace polyphenol extract using reversed phase HPLC system and ultra-performance liquid chromatography (UPLC) system coupled with a quadrupole-time of flight (Q-TOF) MS instrument. Then, we used a well-established animal model of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis to determine the anti-inflammatory action of EP pomace polyphenol extract. We also investigated the effect of the EP pomace polyphenol extract on pro-inflammatory (IL-1ß and TNF-α) cytokine mRNA levels and hydrogen peroxide concentration in the inflamed colon. Administration of EP pomace polyphenol extract significantly improved macroscopic and microscopic damage scores, as well as myeloperoxidase (MPO) activity in TNBS-treated mice. The anti-inflammatory effect of the extract was observed after intracolonic and oral administration and was dose-dependent. Significant reduction of tissue hydrogen peroxide level after treatment with EP pomace polyphenol extract suggests that its therapeutic effect is a result of free radical scavenging. This novel finding indicates that the application of the EP pomace polyphenol extract in patients with inflammatory bowel diseases (IBDs) may become an attractive supplementary treatment for conventional anti-inflammatory therapy.

Activation of the endogenous nociceptin system by selective nociceptin receptor agonist SCH 221510 produces antitransit and antinociceptive effect: a novel strategy for treatment of diarrhea-predominant IBS.

BACKGROUND: Diarrhea-predominant irritable bowel syndrome (IBS-D) is a functional gastrointestinal (GI) disorder, defined by the presence of loose stools and abdominal pain. In search for a novel anti-IBS-D therapy, here we investigated the nociceptin receptor (NOP)-dependent effects in the GI tract. METHODS: A novel potent and selective NOP agonist SCH 221510 was used in the study. The effect of NOP activation on mouse intestinal motility was characterized in vitro and in vivo, in physiological conditions and in animal models of hypermotility and diarrhea. Well-established mouse models of visceral pain were used to characterize the antinociceptive effect of the NOP activation. To provide additional evidence that the endogenous nociceptin system is a relevant target for IBS, NOP expression and nociceptin levels were quantified in serum and colonic biopsies from IBS-D patients. KEY RESULTS: SCH 221510 produced a potent NOP-mediated inhibitory effect on mouse intestinal motility in vitro and in vivo in physiological conditions. The NOP agonist displayed an antidiarrheal and analgesic action after oral administration in animal models mimicking the symptoms of IBS-D. Studies on human samples revealed a strong decrease in endogenous nociceptin system expression in IBS-D patients compared with healthy controls. CONCLUSIONS & INFERENCES: Collectively, mouse and human data suggest that the endogenous nociceptin system is involved in IBS-D and may become a target for anti-IBS-D treatments using potent and selective synthetic NOP agonists.

Transient receptor potential vanilloid 4 blockade protects against experimental colitis in mice: a new strategy for inflammatory bowel diseases treatment?

Recent reports suggested that the activation of Transient Receptor Potential Vanilloid 4 (TRPV4) receptors in the gastrointestinal tract has pro-inflammatory effects. In this study, we demonstrated for the first time that TRPV4 mRNA expression is up-regulated in patients with inflammatory bowel diseases (IBD). Furthermore, selective blockade of TRPV4 in the 2,4,6-trinitrobenzenesulfonic acid animal model alleviates colitis and pain associated with the intestinal inflammation. Our study indicates that TRPV4 may play a role in mechanisms of defense in intestinal inflammation and that TRPV4 may be an attractive target for future systemic or topic anti-inflammatory treatment in patients with IBD.