Mutations in GBA1, encoding glucocerebrosidase beta 1 (GCase), are the most common genetic risk factor for Parkinson's disease (PD). GCase dysfunction leads to an accumulation of glucosylceramide (GluCer) substrates in different organs and fluids. Despite the challenges in quantifying GluCer isoforms in biological samples, their potential clinical interest as PD biomarkers justifies the development of robust assays. An extensively evaluated high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for quantifying 14 GluCer and galactosylceramide (GalCer) isoforms in human cerebrospinal fluid (CSF) samples is presented. Sample pretreatment, HPLC, and MS/MS parameters were optimized. Evaluation was performed according to the recommendations of the Clinical and Laboratory Standards Institute and European Medicines Agency guidelines. Four 7-point calibration curves were generated, with a linearity interval from 2.5 to 200 nM (R2 ≥ 0.995). The limit of quantification was set at 5 nM. Between-run precision and accuracy were up to 12.5 and 9%, respectively. After method validation, we measured the levels of GluCer and GalCer isoforms in CSF human samples, including 6 healthy controls (HC), 22 idiopathic GBA1 wild-type PD (iPD) patients, and 5 GBA1-associated PD (PD-GBA) patients. GluCer/GalCer median ratios were found to be higher in the CSF of PD-GBA patients, particularly in severe GBA1 mutations, than those in iPD and HC. The observed trends in GluCer/GalCer ratios among groups provide novel information for the comprehensive analysis of sphingolipids as potential biomarkers of PD.

Toll-like receptors (TLRs)-mediated host–bacterial interactions participate in the microbial regulation of gastrointestinal functions, including the epithelial barrier function (EBF). We evaluated the effects of TLR7 stimulation on the colonic EBF in rats. TLR7 was stimulated with the selective agonist imiquimod (100/300 µg/rat, intracolonic), with or without the intracolonic administration of dimethyl sulfoxide (DMSO). Colonic EBF was assessed in vitro (electrophysiology and permeability to macromolecules, Ussing chamber) and in vivo (passage of macromolecules to blood and urine). Changes in the expression (RT-qPCR) and distribution (immunohistochemistry) of tight junction-related proteins were determined. Expression of proglucagon, precursor of the barrier-enhancer factor glucagon-like peptide 2 (GLP-2) was also assessed (RT-qPCR). Intracolonic imiquimod enhanced the EBF in vitro, reducing the epithelial conductance and the passage of macromolecules, thus indicating a pro-barrier effect of TLR7. However, the combination of TLR7 stimulation and DMSO had a detrimental effect on the EBF, which manifested as an increased passage of macromolecules. DMSO alone had no effect. The modulation of the EBF (imiquimod alone or with DMSO) was not associated with changes in gene expression or the epithelial distribution of the main tight junction-related proteins (occludin, tricellulin, claudin-2, claudin-3, junctional adhesion molecule 1 and Zonula occludens-1). No changes in the proglucagon expression were observed. These results show that TLR7 stimulation leads to the modulation of the colonic EBF, having beneficial or detrimental effects depending upon the state of the epithelium. The underlying mechanisms remain elusive, but seem independent of the modulation of the main tight junction-related proteins or the barrier-enhancer factor GLP-2.

Parkinson’s disease (PD) is a severe neurodegenerative disease characterized by disabling motor alterations that are diagnosed at a relatively late stage in its development, and non-motor symptoms, including those affecting the gastrointestinal tract (mainly constipation), which start much earlier than the motor symptoms. Remarkably, current treatments only reduce motor symptoms, not without important drawbacks (relatively low efficiency and impactful side effects). Thus, new approaches are needed to halt PD progression and, possibly, to prevent its development, including new therapeutic strategies that target PD etiopathogeny and new biomarkers. Our aim was to review some of these new approaches. Although PD is complex and heterogeneous, compelling evidence suggests it might have a gastrointestinal origin, at least in a significant number of patients, and findings in recently developed animal models strongly support this hypothesis. Furthermore, the modulation of the gut microbiome, mainly through probiotics, is being tested to improve motor and non-motor symptoms and even to prevent PD. Finally, lipidomics has emerged as a useful tool to identify lipid biomarkers that may help analyze PD progression and treatment efficacy in a personalized manner, although, as of today, it has only scarcely been applied to monitor gut motility, dysbiosis, and probiotic effects in PD. Altogether, these new pieces should be helpful in solving the old puzzle of PD.

Sigma-1 receptors (σ1Rs) are implicated in nociception, including pain sensitization, and inflammation. We assessed the role of σ1Rs on acute colitis-associated hypersensitivity using both genetic (constitutive knockout) and pharmacological blockade of the receptor. Colitis was induced in CD1 wild-type (WT) and σ1R KO mice (exposure to dextran sodium sulfate, 3%). A von Frey test was used to assess referred mechanosensitivity (abdominal and plantar withdrawal responses). The effects of the selective σ1R antagonists BD1063 and E-52862 were also assessed in WT animals. The expression of immune and sensory-related markers (RT-qPCR, Western blot) was assessed in the colon and lumbosacral spinal cord. The genetic ablation or pharmacological blockade of σ1Rs attenuated acute colonic inflammation in a similar manner. Mechanosensitivity was similar in WT and σ1R KO mice before colitis. In WT mice, but not in σ1R KO, colitis was associated with the development of referred mechanical hypersensitivity, manifested as a reduction in the withdrawal thresholds to mechanical probing (paw and abdominal wall). In WT mice, BD1063 and E-52862 blocked colitis-associated hypersensitivity. A genotype- and treatment-related differential regulation of sensory-related markers was detected locally (colon) and within the spinal cord. σ1Rs are involved in the development of acute intestinal inflammation and its associated referred mechanical hypersensitivity. The selective modulation of sensory-related pathways within the colon and spinal cord might be part of the underlying mechanisms. These observations support the pharmacological use of σ1R antagonists for the treatment of intestinal inflammation-induced hypersensitivity.

BACKGROUND:Persistent visceral hypersensitivity is a key component of functional and inflammatory gastrointestinal diseases. Current animal models fail to fully reproduce the characteristics of visceral pain in humans, particularly as it relates to persistent hypersensitivity. This work explores the validity of DSS-induced colitis in rats as a model to mimic chronic intestinal hypersensitivity.METHODS:Exposure to DSS (5% for 7 days) was used to induce colitis in rats. Thereafter, changes in viscerosensitivity (visceromotor responses to colorectal distension-CRD), the presence of somatic referred pain (mechanosensitivity of the hind paws, von Frey test) and the expression (qRT-PCR) of sensory-related markers (colon, lumbosacral DRGs, and lumbosacral spinal cord) were assessed at different times during the 35 days period after colitis induction.RESULTS:Following colitis, a sustained increase in visceromotor responses to CRD were observed, indicative of the presence of visceral hypersensitivity. Responses in animals without colitis remained stable over time. In colitic animals, somatic referred hypersensitivity was also detected. DSS-induced colitis was associated to a differential expression of sensory-related markers (with both pro- and anti-nociceptive action) in the colon, lumbosacral DRGs and lumbosacral spinal cord; indicating the presence of peripheral and central sensitization.CONCLUSIONS AND INFERENCES:DSS-induced colitis in rats is associated to the generation of a long-lasting state of visceral (colonic) hypersensitivity, despite clinical colitis resolution. This model reproduces the changes in intestinal sensitivity characteristics of inflammatory and functional gastrointestinal disorders in humans and can be used in the characterization of new pharmacological treatments against visceral pain.

Rifaximin is a broad-spectrum antibiotic that ameliorates symptomatology in inflammatory/functional gastrointestinal disorders. We assessed changes in gut commensal microbiota (GCM) and Toll-like receptors (TLRs) associated to rifaximin treatment in mice. Adult C57BL/6NCrl mice were treated (7/14 days) with rifaximin (50/150 mg/mouse/day, PO). Luminal and wall-adhered ceco-colonic GCM were characterized by fluorescent in situ hybridization (FISH) and microbial profiles determined by terminal restriction fragment length polymorphism (T-RFLP). Colonic expression of TLR2/3/4/5/7 and immune-related markers was assessed (RT-qPCR). Regardless the period of treatment or the dose, rifaximin did not alter total bacterial counts or bacterial biodiversity. Only a modest increase in Bacteroides spp. (150 mg/1-week treatment) was detected. In control conditions, only Clostridium spp. and Bifidobacterium spp. were found attached to the colonic epithelium. Rifaximin showed a tendency to favour their adherence after a 1-week, but not 2-week, treatment period. Minor up-regulation in TLRs expression was observed. Only the 50 mg dose for 1-week led to a significant increase (by 3-fold) in TLR-4 expression. No changes in the expression of immune-related markers were observed. Rifaximin, although its antibacterial properties, induces minor changes in luminal and wall-adhered GCM in healthy mice. Moreover, no modulation of TLRs or local immune systems was observed. These findings, in normal conditions, do not rule out a modulatory role of rifaximin in inflammatory and or dysbiotic states of the gut.

Mast cells are key actors in inflammatory reactions. Upon activation, they release histamine, heparin and nerve growth factor, among many other mediators that modulate immune response and neuron sensitization. One important feature of mast cells is that their population is usually increased in animal models and biopsies from patients with irritable bowel syndrome (IBS). Therefore, mast cells and mast cell mediators are regarded as key components in IBS pathophysiology. IBS is a common functional gastrointestinal disorder affecting the quality of life of up to 20% of the population worldwide. It is characterized by abdominal pain and altered bowel habits, with heterogeneous phenotypes ranging from constipation to diarrhea, with a mixed subtype and even an unclassified form. Nutrient intake is one of the triggering factors of IBS. In this respect, certain components of the daily food, such as fatty acids, amino acids or plant-derived substances like flavonoids, have been described to modulate mast cells’ activity. In this review, we will focus on the effect of these molecules, either stimulatory or inhibitory, on mast cell degranulation, looking for a nutraceutical capable of decreasing IBS symptoms.

The management of pain, particularly chronic pain, is still an area of medical need. In this context, opioids remain a gold standard for the treatment of pain. However, significant side effects, mainly of central origin, limit their clinical use. Here, we review recent progress to improve the therapeutic and safety profiles of opioids for pain management. Characterization of peripheral opioid-mediated pain mechanisms have been a key component of this process. Several studies identified peripheral µ, δ, and κ opioid receptors (MOR, DOR, and KOR, respectively) and nociceptin/orphanin FQ (NOP) receptors as significant players of opioid-mediated antinociception, able to achieve clinically significant effects independently of any central action. Following this, particularly from a medicinal chemistry point of view, main efforts have been directed towards the peripheralization of opioid receptor agonists with the objective of optimizing receptor activity and minimizing central exposure and the associated undesired effects. These activities have allowed the characterization of a great variety of compounds and investigational drugs that show low central nervous system (CNS) penetration (and therefore a reduced side effect profile) yet maintaining the desired opioid-related peripheral antinociceptive activity. These include highly hydrophilic/amphiphilic and massive molecules unable to easily cross lipid membranes, substrates of glycoprotein P (a extrusion pump that avoids CNS penetration), nanocarriers that release the analgesic agent at the site of inflammation and pain, and pH-sensitive opioid agonists that selectively activate at those sites (and represent a new pharmacodynamic paradigm). Hopefully, patients with pain will benefit soon from the incorporation of these new entities.

Cannabis sativa is an aromatic annual flowering plant with several botanical varieties, used for different purposes, like the production of fibers, the production of oil from the seeds, and especially for recreational or medical purposes. Phytocannabinoids (terpenophenolic compounds derived from the plant), include the well-known psychoactive cannabinoid Δ9-tetrahydrocannabinol, and many non-psychoactive cannabinoids, like cannabidiol. The endocannabinoid system (ECS) comprises of endocannabinoid ligands, enzymes for synthesis and degradation of such ligands, and receptors. This system is widely distributed in the gastrointestinal tract, where phytocannabinoids exert potent effects, particularly under pathological (i.e., inflammatory) conditions. Herein, we will first look at the hemp plant as a possible source of new functional food ingredients and nutraceuticals that might be eventually useful to treat or even prevent gastrointestinal conditions. Subsequently, we will briefly describe the ECS and the general pharmacology of phytocannabinoids. Finally, we will revise the available data showing that non-psychoactive phytocannabinoids, particularly cannabidiol, may be useful to treat different disorders and diseases of the gastrointestinal tract. With the increasing interest in the development of functional foods for a healthy life, the non-psychoactive phytocannabinoids are hoped to find a place as nutraceuticals and food ingredients also for a healthy gastrointestinal tract function.

Introduction: Splanchnic mast cells increase in chronic liver and in acute-on-chronic liver diseases. We administered Ketotifen, a mast cell stabilizer, and measured the mast cells in the splanchnic organs of cholestatic rats. Material and Methods: These groups were studied: sham-operated rats (S; n= 15), untreated microsurgical cholestasic rats (C; n= 20) and rats treated with Ketotifen: early (SK-e; n= 20 and CKe; n= 18), and Late (SK-l; n= 15 and CK-l; n= 14). Results: The cholestatic rats showed systemic and splanchnic impairments, such as ascites, portal hypertension, and biliary proliferation and fibrosis. The rats also showed a splanchnic increase of TNF-alpha, IL-1 beta and MCP-1, and a reduction of IL-4, IL-10 and antioxidants. An increase of VEGF in the ileum and mesenteric lymphatic complex was associated with a liver reduction of TGF-beta 1. Ketotifen reduces the degree of hepatic insufficiency and the splanchnic inflammatory mediators, as well as VEGF and TGF-beta 1 levels. Ketotifen also reduces the connective tissue mast cells in the mesenteric lymphatic complex of cholestatic rats, while increases the hepatic mucosal mast cells. Conclusions: In cholestatic rats, Ketotifen improves liver function and ascites, and also reduces pro-inflammatory mediators in the splanchnic area. The decrease in connective tissue mast cells in the mesenteric lymphatic complex due to the administration of Ketotifen would lead to the improvement of the inflammatory splanchnic response, and consequently the abovementioned complications. (C) 2019 Elsevier Masson SAS. All rights reserved.

The inflammatory response expressed after wound healing would be the recapitulation of systemic extra-embryonic functions, which would focus on the interstitium of the injured tissue. In the injured tissue, mast cells, provided for a great functional heterogeneity, could play the leading role in the re-expression of extra-embryonic functions, i.e., coelomic–amniotic and trophoblastic–vitelline. Moreover, mast cells would favor the production of a gastrulation-like process, which in certain tissues and organs would induce the regeneration of the injured tissue. Therefore, the engraftment of mesenchymal stem cells and mast cells, both with an extra-embryonic regenerative phenotype, would achieve a blastema, from the repaired and regenerated injured tissue, rather than by fibrosis, which is commonly made through wound-healing.

Background: Sigma-1 receptors (σ1Rs) have immunomodulatory properties and have been shown to modulate gene expression of several proteins related to inflammation. Indeed, σ1R modulation has been suggested to be potentially useful in pathologies where pro-inflammatory cytokines are involved. Here we assessed the potential implication of σ1Rs on colitis using a murine model knockout for σ1Rs. Methods: Adult CD-1 male wild type (WT) and σ1R knockout mice (σ1R KO) were used. Colitis was induced by exposure to a 3% solution of dextran sodium sulfate (DSS) during a 5-day period, followed by a 3-day recovery. Body weight and clinical signs were assessed on a daily basis. At termination, colonic inflammation was assessed macro and microscopically (Stress 2008,11:348–62). Colonic expression of pro- (Interferon -INF-, IL-1, IL-6, IL-18 and IL-12p40) and anti-inflammatory cytokines (IL-10) was also determined (RT-qPCR). Results: During colitis induction, body weight loss and clinical signs were attenuated in σ1R KO vs. WT animals. At necropsy, colonic inflammatory score, changes in colon length and relative weight and colonic histopathological scores were also attenuated in σ1R KO mice (Table 1). Improvement in histopathological scores was due mainly to a reduction in submucosal edema. Basal expression of cytokines was similar in WT and σ1R KO mice, except for IL-12p40 which was up-regulated by 4-fold in σ1R KO mice (p<0.05 vs. WT). During colitis, INF, IL-1 and IL-6 were up-regulated in WT mice (all p<0.05 vs. non-inflamed WT), while only minor expression changes were observed in KO animals (all p>0.05 vs. non-inflamed σ1R KO mice). IL-12p40 showed a selective down-regulation in colitic σ1R KO mice while IL-18 showed minor, non-significant, changes. Regardless the phenotype considered, no changes in IL-10 expression were detected. Expression of σ1Rs was detected in the colon of WT mice, but not in KO animals. In WT mice, σ1R expression was reduced by 28% (p<0.05) during colitis. Table 1 Data are mean ± SEM, n=12–13 animals per group. *p<0.05 vs. respective water-treated group; #p<0.05 vs. WT-DSS group. Conclusions: Lack of functional σ1Rs resulted in an attenuated inflammatory and immune response in the DDS-induced colitis model in mice. These results indicate that σ1Rs are implicated in the modulation of intestinal inflammation. Antagonism of σ1Rs might represent a pharmacological approach for the treatment of intestinal inflammation.

Background: Intestinal inflammation is associated to both visceral and somatic hypersensitivity. Several studies show that sigma-1 receptors (σ1Rs) are implicated in pain and pain sensitization. We assessed the role of σ1Rs on colitis-associated changes in somatic and visceral sensitivity, using a murine model knockout for σ1Rs. Methods: Adult CD-1 male wild type (WT) and σ1R knockout mice (σ1R KO) were used. Colitis was induced by exposure to a 3% solution of dextran sodium sulfate (DSS) during a 5-day period (experimental days 0 to 5), followed by a 2-day recovery. A von Frey test was used to assess changes in somatic (plantar withdrawal response) and visceral mechanosensitivity (abdominal withdrawal response). Changes in mechanosensitivity were assessed before (experimental day −1), during (experimental day 3) and after colitis induction (experimental day 7). At termination, colonic expression (RT-qPCR) of several receptors involved in visceral sensitivity, including cannabinoid receptors (CB1, CB2) and μ-opioid receptor (MOR), was assessed. Results: σ1R KO mice showed attenuated clinical signs and colonic inflammation as assessed macro and microscopically. Somatic and visceral mechanosensitivity was similar in WT and σ1R KO mice before the induction of colitis (Table 1). In WT mice colitis was associated to a time-related development of somatic and visceral mechanical hypersensitivity (Table). In σ1R KO neither somatic nor visceral mechanical sensitivity was altered during inflammation (Table). Basal expression of CB1 and MOR was similar in WT and σ1R KO mice, while CB2 was up-regulated in σ1R KO mice. Regardless the phenotype considered, CB1 and MOR were down-regulated during colitis, while no changes in CB2 expression were observed. Table 1. Data are mean ± SEM, n=6–8 per group. *p<0.05 vs. day −1. Conclusions: Intestinal inflammation-associated visceral and somatic hypersensitivity was absent in σ1R KO mice, thus indicating that σ1Rs are involved in pain sensitization. Antagonism of σ1Rs might represent an attractive pharmacological approach for the treatment of visceral and somatic hypersensitivity.

Background: Dysbiosis and altered host-bacterial interactions are a common feature of intestinal inflammation. Spontaneous colitis in Interleukin 10 knockout (IL-10 KO) mice seems to be associated to the presence of dysbiosis. We assessed changes in gut commensal microbiota (GCM) and host-bacterial interaction systems (toll like receptors – TLR – and antimicrobial peptides – AMP) during colitis development in IL-10 KO mice. Methods: Wild type (WT) and IL-10 KO mice were bread under barrier conditions; at 4-wk of age animals were moved to a conventional facility for an additional 8-wk period. Colitis and GCM were assessed in 4-wk-old (WT, n=5; KO, n=6) and 12-wk-old animals (WT, n=4; KO, n=5). GCM was evaluated from stools (pyrosequencing of 16S rDNA). Expression of pro-inflammatory markers (INF-γ, IL-12p40, TNF-α and iNOS), AMPs (regenerating islet-derived 3γ – Reg3γ – and defensin α6/24 – Defα6/24) and TLR2/3/4/5/7 was assessed by RT-qPCR. Results: In 4-wk-old mice no signs of colitis were observed. GCM was similar in IL-10 KO and WT mice; with a predominance of Firmicutes (WT: 80%, IL-10 KO: 73%) and Bacteroidetes (WT: 17%, IL-10 KO: 25%). 12-wk-old IL-10 KO mice showed signs of colitis (increased relative colonic weight and histopathological scores; 100% incidence) and an up-regulation of pro-inflammatory markers vs. 10-wk-old WT mice. At this time, WT and IL-10 KO mice showed similar adaptive changes of their GCM (Firmicutes: 46% in WT, 30% in IL-10 KO; Bacteroidetes: 50% in WT, 68% in IL-10 KO). However, Verrucomicrobia (genus Akkermansia) increased significantly in IL-10 KO mice (95-fold vs. 3-fold in WT). Similarly, the genus Alistipes (phylum Bacteroidetes) appeared in the WT at detectable levels and increased by 50-fold in IL-10 KO mice. Verrucobacteria (p<0.001) and Alistipes (p<0.01) proportions correlated positively with histopathological scores. 12-wk-old IL-10 KO mice showed a general down-regulation of TLRs (50–75% vs. WT, p<0.001 in all cases), an up-regulation of the AMP Reg3γ (12-fold vs. WT, p<0.001) and a down-regulation of Defα6/24 (0.8-fold vs. WT; p<0.05). Conclusions: When moved to standard conditions, similar adaptive changes of GCM were observed in WT and IL-10 KO mice, although only IL-10 KO mice developed colitis. Increased proportions of Verrucobacteria and Alistipes were observed in IL-10 KO mice with colitis. Colitic IL-10 KO mice showed also alterations in host-bacterial interaction systems. These observations support the implication of Verrucobacteria and Alistipes in intestinal inflammation, although the cause-effect relationship remains unclear. Dysbiosis and altered host-bacterial interactions might contribute to the development and maintenance of intestinal inflammation.

colitis was induced in male Sprague-Dawley rats by a 2,4,6-trinitrobenzenesulfonic acid (TNBS) enema; controls received 0.9% NaCl.At day 3, a colonoscopy was performed to confirm the presence of colitis and then repeated every 4 days, from day 10 onwards, to follow up mucosal healing.Three days after complete resolution of colitis, visceral sensitivity was examined by quantifying visceromotor responses (VMRs) to colorectal distension (10-60mmHg, 20s, 4min interval); expressed as total area under the curve (AUC; µV/20s).The serine protease inhibitor FUT-175 (0.1-1mg/kg), SPIx (0.01-0.1-1mg/kg) or vehicle was injected intraperitoneally (ip), 30 min before the VMR experiment.Finally, the inflammatory parameters (colonoscopy, macroscopy, microscopy and myeloperoxidase activity) were scored to confirm the post-inflammatory status at the time of the VMR.Results: At day 3, TNBS rats displayed a mild colitis, which was completely resolved at day 10-18 endoscopically.The post-inflammatory status of the TNBS group at the day of the VMR was confirmed for all animals in both experimental setups.All vehicle-treated post-colitis rats showed significantly higher VMRs compared to controls (table 1 & 2; *), indicating visceral hypersensitivity.FUT-175 significantly decreased visceral hypersensitivity (table 1; #): in a dose of 0.1 mg/kg significance was reached at 30-60 mmHg (table 1; #), whereas the 1 mg/kg dose significantly lowered VMRs at 10-30 mmHg (table 1; #).SPIx also significantly decreased visceral hypersensitivity with a clear dose-dependent effect: 0.01 mg/kg SPIx had no significant effect, whereas 0.1 mg/kg significantly reduced the VMRs at 30-60 mmHg and 1 mg/ kg SPIx completely reversed colitis-induced visceral hypersensitivity at 20-60 mmHg (table 2; #).The effective doses of FUT-175 and SPIx had no effect on visceral sensitivity in control animals.Conclusion: Our results support an important role for serine protease inhibitors in the search for new treatments for abdominal pain in post-inflammatory IBS patients.However, complete reversal of the hypersensitivity was only achieved with the newly developed tryptase/matriptase inhibitor SPIx, emphasizing the importance of the inhibitor specificity.

colitis was induced in male Sprague-Dawley rats by a 2,4,6-trinitrobenzenesulfonic acid (TNBS) enema; controls received 0.9% NaCl.At day 3, a colonoscopy was performed to confirm the presence of colitis and then repeated every 4 days, from day 10 onwards, to follow up mucosal healing.Three days after complete resolution of colitis, visceral sensitivity was examined by quantifying visceromotor responses (VMRs) to colorectal distension (10-60mmHg, 20s, 4min interval); expressed as total area under the curve (AUC; µV/20s).The serine protease inhibitor FUT-175 (0.1-1mg/kg), SPIx (0.01-0.1-1mg/kg) or vehicle was injected intraperitoneally (ip), 30 min before the VMR experiment.Finally, the inflammatory parameters (colonoscopy, macroscopy, microscopy and myeloperoxidase activity) were scored to confirm the post-inflammatory status at the time of the VMR.Results: At day 3, TNBS rats displayed a mild colitis, which was completely resolved at day 10-18 endoscopically.The post-inflammatory status of the TNBS group at the day of the VMR was confirmed for all animals in both experimental setups.All vehicle-treated post-colitis rats showed significantly higher VMRs compared to controls (table 1 & 2; *), indicating visceral hypersensitivity.FUT-175 significantly decreased visceral hypersensitivity (table 1; #): in a dose of 0.1 mg/kg significance was reached at 30-60 mmHg (table 1; #), whereas the 1 mg/kg dose significantly lowered VMRs at 10-30 mmHg (table 1; #).SPIx also significantly decreased visceral hypersensitivity with a clear dose-dependent effect: 0.01 mg/kg SPIx had no significant effect, whereas 0.1 mg/kg significantly reduced the VMRs at 30-60 mmHg and 1 mg/ kg SPIx completely reversed colitis-induced visceral hypersensitivity at 20-60 mmHg (table 2; #).The effective doses of FUT-175 and SPIx had no effect on visceral sensitivity in control animals.Conclusion: Our results support an important role for serine protease inhibitors in the search for new treatments for abdominal pain in post-inflammatory IBS patients.However, complete reversal of the hypersensitivity was only achieved with the newly developed tryptase/matriptase inhibitor SPIx, emphasizing the importance of the inhibitor specificity.

Background Visceral hypersensitivity in the inflamed gut is related partly to the effects of peripheral neurotrophic factors (NTFs) on local afferent neurons. However, alterations in sensory afferents of distant areas remain unexplored. Using the Trichinella spiralis infection model, which causes a jejunitis, we investigated the remodeling of colonic afferents and the potential role of NTFs. Methods Rats were infected with T. spiralis. Inflammatory-like changes, mucosal mast cells (MMCs) dynamics, and expression of nerve growth factor and glial cell line-derived NTFs (glial cell-derived neurotrophic factor, artemin, and neurturin) were determined in the colon up to day 30 postinfection. Functional responses of colonic afferents were determined assessing changes in the expression of sensory-related markers in thoracolumbar (TL)/lumbosacral (LS) dorsal root ganglias (DRGs) following intracolonic capsaicin. Key Results Trichinella spiralis induced an inflammatory-like response within the colon, partly resolved at day 30 postinfection, except for a persistent MMC infiltrate. While the jejunum of infected animals showed an up-regulation in the expression of NTFs, a transitory down-regulation was observed in the colon. Overall, T. spiralis effects on DRGs gene expression were restricted to a transient down-regulation of TPRV1. Stimulation with intracolonic capsaicin induced a down-regulation of TRPV1 levels in TL and LS DRGs, an effect enhanced in LS DRGs of infected animals, regardless the postinfection time considered. Conclusions & Inferences During intestinal inflammation, spread morphological and functional alterations, including remodeling of visceral afferents, are observed outside the primary region affected by the insult. Similar mechanisms might be operating in states of widespread alterations of visceral sensitivity.