Translational evaluation of Gelsectan® effects on gut barrier dysfunction and visceral pain in animal models and irritable bowel syndrome with diarrhoea.

BACKGROUND: Gelsectan® is a formulation of xyloglucan (XG), pea protein, grape seed extract (PPGS) and xylo-oligosaccharides (XOS). Our aim was to examine the effect of Gelsectan® on rectal sensitivity in an animal model, abdominal pain in irritable bowel syndrome with diarrhoea (IBS-D) subjects and intestinal permeability in both conditions. METHODS: Animals: Wistar rats received gavage with XOS, XG + PPGS or XG + PPGS + XOS, as a single dose or for 7 days before a partial restraint stress (PRS). Visceromotor response to rectal distension and total gut paracellular permeability to 51Cr-EDTA were assessed. Humans: IBS-D and control patients were involved. After initial colonoscopy with biopsy sampling Gelsectan® was administered to IBS-D patients for 12 weeks. Stool count and pain scores were documented. After treatment, colonoscopy was repeated. The permeability of biopsy samples was measured in Ussing-chambers. Adherent mucus layer, Muc-2 expression as well as TNFα, Interferon IFNγ were evaluated by histology/immunohistochemistry and ELISA assays, respectively. RESULTS: Animal studies: In control rats, PRS significantly increased visceromotor response as well as gut paracellular permeability. Single dose administration of XG + PPGS + XOS failed to reverse PRS, but 7 days of oral treatment reversed PRS-induced rectal hypersensitivity and gut hyperpermeability. Human studies: Gelsectan® treatment significantly reduced and abdominal pain. Intestinal permeability in IBS-D patients was elevated compared with controls, Gelsectan® restored permeability in the ascendent colon. Periodic acid-Schiff-stained mucus layer was significantly thinner in IBS-D patients compared with controls, In both segments, mucus thickness and the proportion of Muc-2 positive cells were not affected by Gelsectan® treatment. IFNγ tissue level in the sigmoid colon shows modest mucosal inflammation in IBS-D. CONCLUSIONS: Gelsectan® prevented rectal hypersensitivity in rats, abdominal pain in human and intestinal hyperpermeability in rat and human studies respectively. These effects involve restoration of gut permeability. Based on this translational study, Gelsectan® can be considered as an effective therapy for IBS-D symptoms.

Effect of diet supplemented with functional amino acids and polyphenols on gut health in broilers subjected to a corticosterone-induced stress.

To address the overuse of antimicrobials in poultry production, new functional feed ingredients, i.e. ingredients with benefits beyond meeting basic nutritional requirements, can play a crucial role thanks to their prophylactic effects. This study evaluated the effects of the supplementation of arginine, threonine and glutamine together with grape polyphenols on the gut integrity and functionality of broilers facing a stress condition. 108 straight-run newly hatched Ross PM3 chicks were kept until 35 days and were allocated to 3 treatments. Broilers in the control group were raised in standard conditions. In experimental groups, birds were administered with corticosterone in drinking water (CORT groups) to impair the global health of the animal and were fed a well-balanced diet supplemented or not with a mix of functional amino acids together with grape extracts (1 g/kg of diet-CORT + MIX group). Gut permeability was significantly increased by corticosterone in non-supplemented birds. This corticosterone-induced stress effect was alleviated in the CORT + MIX group. MIX supplementation attenuated the reduction of crypt depth induced by corticosterone. Mucin 2 and TNF-α gene expression was up-regulated in the CORT + MIX group compared to the CORT group. Caecal microbiota remained similar between the groups. These findings indicate that a balanced diet supplemented with functional AA and polyphenols can help to restore broiler intestinal barrier after a stress exposure.

Effect of xyloglucan associations with gelatin or gelose on Escherichia coli-derived lipopolysaccharide-induced enteritis in rats.

Background: Escherichia coli is the predominant non-pathogenic facultative microbe of the human intestine, although some strains are diarrhoeagenic in humans. E. coli-derived lipopolysaccharide (LPS) induces diarrhoea, intestinal barrier impairment, bacterial translocation and intestinal inflammation. Associations with the mucoprotectant xyloglucan exhibit antidiarrhoeal effects. This study evaluated and compared the effects of xyloglucan in combination with gelatin or gelose (agar-agar) on jejunal permeability and inflammation using an in vivo rat model of E. coli LPS-induced enteritis. Methods: Xyloglucan (12.5 mg/kg) plus gelatin (250 mg/kg) or gelose (250 or 500 mg/kg) were administered orally 2 hours before intraperitoneal injection with E. coli LPS. Following euthanasia, jejunal segments were removed for intestinal permeability measurement in Ussing chambers and inflammatory tone evaluation by myeloperoxidase activity assay. Results: LPS administration increased jejunal permeability and increased mucosal inflammation in male Wistar rats. Xyloglucan plus gelatin 250 mg/kg and xyloglucan plus gelose 500 mg/kg significantly attenuated LPS-induced jejunal hyperpermeability and myeloperoxidase activity. Conclusion: Xyloglucan, a known mucosal barrier protector, in combination with gelatin or gelose, has beneficial and comparable effects on intestinal permeability and inflammation following E. coli LPS insult in male rats.

Lactococcus lactis CNCM I-5388 versus NCDO2118 by its GABA hyperproduction ability, counteracts faster stress-induced intestinal hypersensitivity in rats.

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by its main symptom, visceral hypersensitivity (VH), which is aggravated by stress. Gut-brain interactions and gut bacteria may alleviate IBS symptoms, including VH. γ-amino butyric acid (GABA), produced notably by lactic acid bacteria (LAB), shows promising result in IBS symptoms treatment. In bacteria, GABA is generated through glutamate decarboxylase (GAD) metabolism of L-glutamic acid, maintaining intracellular pH. In mammals, GABA acts as an inhibitory neurotransmitter, modulating pain, stress, and anxiety. Therefore, utilizing GABA-producing LAB as a therapeutic approach might be beneficial. Our previous work showed that a GABA-producing Lactococcus lactis strain, NCDO2118, reduced VH induced by acute stress in rats after a 10-day oral treatment. Here, we identified the strain CNCM I-5388, with a four-fold higher GABA production rate under the same conditions as NCDO2118. Both strains shared 99.1% identical GAD amino acid sequences and in vitro analyses revealed the same optimal pH for GAD activity; however, CNCM I-5388 exhibited 17 times higher intracellular GAD activity and increased resistance to acidic pH. Additionally, in vivo experiments have demonstrated that CNCM I-5388 has faster anti-VH properties in rats compared with NCDO2118, starting from the fifth day of treatment. Finally, CNCM I-5388 anti-VH effects partially persisted after 5-day treatment interruption and after a single oral treatment. These findings highlight CNCM I-5388 as a potential therapeutic agent for managing VH in IBS patients.

Microbial Dynamics during labneh Ambaris Production in Earthenware Jars.

The responses of various microbial populations to modifications in the physicochemical properties of a food matrix, as well as interactions between these populations already present, are the main factors that shape microbial dynamics in that matrix. This work focused on the study of microbial dynamics during labneh Ambaris production, a traditional Lebanese concentrated fermented goat milk made in jars during 3 months. This was assessed in two earthenware jars at a production facility. DNA metabarcoding of the ITS2 region as well as the V3-V4 region of the 16S rRNA gene was used to characterize the fungal and bacterial communities, respectively. Viable bacterial isolates were also identified by Sanger sequencing of the V1-V4 region of the 16S rRNA gene. Our results showed that the dominant microorganisms identified within labneh Ambaris (Lactobacillus kefiranofaciens, Lentilactobacillus kefiri, Lactococcus lactis, Geotrichum candidum, Pichia kudriavzevii and Starmerella sp.) settle early in the product and remain until the end of maturation with varying abundances throughout fermentation. Microbial counts increased during early fermentation stage, and remained stable during mid-fermentation, then declined during maturation. While microbial compositions were globally comparable between the two jars during mid-fermentation and maturation stages, differences between the two jars were mainly detected during early fermentation stage (D0 until D10). No significant sensorial differences were observed between the final products made in the two jars. Neither coliforms nor Enterobacteriaceae were detected in their viable state, starting D7 in both jars, suggesting the antimicrobial properties of the product.

Microbial communities and main features of labneh Ambaris, a traditional Lebanese fermented goat milk product.

Labneh Ambaris is a traditional Lebanese dairy product typically made using goat milk in special earthenware jars. Its production is characterized by the regular additions of milk and coarse salt, all while draining the whey throughout a process that lasts for a minimum of 2 mo. In this study, 20 samples of labneh Ambaris, all produced by spontaneous fermentation, were studied. They were collected at the end of fermentation from different regions in Lebanon. Physicochemical and sensory properties were studied and microbial diversity was analyzed using culture-dependent and independent techniques. The V3-V4 region of the 16S rRNA gene and the ITS2 region were sequenced by DNA metabarcoding analyses for the identification of bacteria and yeast communities, respectively. Out of 160 bacterial and 36 fungal taxa, 117 different bacterial species and 24 fungal species were identified among all labneh Ambaris samples studied. The remaining ones were multi-affiliated and could not be identified at the species level. Lactobacillus was the dominant bacterial genus, followed by Lentilactobacillus, Lactiplantibacillus, Lacticaseibacillus, and Lactococcus genera, whereas Geotrichum and Pichia were the dominant fungal genera. The 20 samples tested had varying levels of salt, protein, and fat contents, but they were all highly acidic (mostly having a pH < 4). According to the sensory scores generated by classical descriptive analysis, all samples were described as having basic similar characteristics such as goat smell and flavor, but they could be differentiated based on various intensities within the same descriptors like salty and acidic. This work could be considered as a base toward obtaining a quality label for labneh Ambaris.

Artisanal Household Milk Pasteurization Is Not a Determining Factor in Structuring the Microbial Communities of Labneh Ambaris: A Pilot Study.

Labneh Ambaris is a traditional Lebanese dairy product traditionally made using raw goat's milk in earthenware jars, but recently the use of artisanally pasteurized milk was introduced for safety reasons. In this study, 12 samples of labneh Ambaris were studied, six made using raw goat's milk and six others using artisanally pasteurized goat's milk. These samples were collected during fermentation and their microbial compositions were analyzed. The 16S V3-V4 and the ITS2 regions of the rDNA were sequenced by DNA metabarcoding analyses for the identification and comparison of bacterial and fungal communities, respectively. The samples had high microbial diversity but differences in samples microbiota were unrelated to whether or not milk was pasteurized. The samples were consequently clustered on the basis of their dominant bacterial or fungal species, regardless of the milk used. Concerning bacterial communities, samples were clustered into 3 groups, one with a higher abundance of Lactobacillus helveticus, another with Lactobacillus kefiranofaciens as the dominant bacterial species, and the third with Lentilactobacillus sp. as the most abundant species. Species belonging to the Enterobacteriaceae family were detected in higher abundance in all raw milk samples than in artisanally pasteurized milk samples. As for fungal communities, the samples were clustered into two groups, one dominated by Geotrichum candidum and the other by Pichia kudriavzevii.

Lactococcus lactis NCDO2118 exerts visceral antinociceptive properties in rat via GABA production in the gastro-intestinal tract.

Gut disorders associated to irritable bowel syndrome (IBS) are combined with anxiety and depression. Evidence suggests that microbially produced neuroactive molecules, like γ-aminobutyric acid (GABA), can modulate the gut-brain axis. Two natural strains of Lactococcus lactis and one mutant were characterized in vitro for their GABA production and tested in vivo in rat by oral gavage for their antinociceptive properties. L. lactis NCDO2118 significantly reduced visceral hypersensitivity induced by stress due to its glutamate decarboxylase (GAD) activity. L. lactis NCDO2727 with similar genes for GABA metabolism but no detectable GAD activity had no in vivo effect, as well as the NCDO2118 ΔgadB mutant. The antinociceptive effect observed for the NCDO2118 strain was mediated by the production of GABA in the gastro-intestinal tract and blocked by GABAB receptor antagonist. Only minor changes in the faecal microbiota composition were observed after the L. lactis NCDO2118 treatment. These findings reveal the crucial role of the microbial GAD activity of L. lactis NCDO2118 to deliver GABA into the gastro-intestinal tract for exerting antinociceptive properties in vivo and open avenues for this GRAS (Generally Recognized As safe) bacterium in the management of visceral pain and anxious profile of IBS patients.

Human milk oligosaccharides alleviate stress-induced visceral hypersensitivity and associated microbiota dysbiosis.

Pain-related functional gastrointestinal disorders (FGIDs) are characterized by visceral hypersensitivity (VHS) associated with alterations in the microbiota-gut-brain axis. Since human milk oligosaccharides (HMOs) modulate microbiota, gut and brain, we investigated whether HMOs impact VHS, and explored the role of gut microbiota. To induce VHS, C57BL/6JRj mice received hourly water avoidance stress (WAS) sessions for 10 d, or antibiotics (ATB) for 12 d. Challenged and unchallenged (Sham) animals were fed AIN93M diet (Cont) or AIN93M containing 1% of a 6-HMO mix (HMO6). VHS was assessed by monitoring the visceromotor response to colorectal distension. Fecal microbiome was analyzed by shotgun metagenomics. The effect of HMO6 sub-blends on VHS and nociceptive pathways was further tested using the WAS model. In mice fed Cont, WAS and ATB increased the visceromotor response to distension. HMO6 decreased WAS-mediated electromyographic rise at most distension volumes and overall Area Under Curve (AUC=6.12±0.50 in WAS/HMO6 vs. 9.46±0.50 in WAS/Cont; P<.0001). In contrast, VHS in ATB animals was not improved by HMO6. In WAS, HMO6 promoted most microbiota taxa and several functional pathways associated with low VHS and decreased those associated with high VHS. Among the sub-blends, 2'FL+DFL and LNT+6'SL reduced visceromotor response close to Sham/Cont values and modulated serotoninergic and CGRPα-related pathways. This research further substantiates the capacity of HMOs to modulate the microbiota-gut-brain communication and identifies mitigation of abdominal pain as a new HMO benefit. Ultimately, our findings suggest the value of specific HMO blends to alleviate pain associated FGIDs such as infantile colic or Irritable Bowel Syndrome.

The Infant-Derived Bifidobacterium bifidum Strain CNCM I-4319 Strengthens Gut Functionality.

Bifidobacteria are among the first colonisers of the gastrointestinal tract of breast-fed newborns due to, among other things, their ability to metabolise oligosaccharides naturally occurring in human milk. The presence of bifidobacteria in the infant gut has been shown to promote intestinal health and homeostasis as well as to preserve a functional gut barrier, thus positively influencing host health and well-being. Among human-associated gut commensals, Bifidobacterium bifidum has been described as the only species capable of the extracellular degradation of both mucin-type glycans and HMOs, thereby giving this species a special role as a commensal gut forager of both host and diet-derived glycans. In the present study, we assess the possible beneficial properties and probiotic potential of B. bifidum strain CNCM I-4319. In silico genome analysis and growth experiments confirmed the expected ability of this strain to consume HMOs and mucin. By employing various animal models, we were also able to assess the ability of B. bifidum CNCM I-4319 to preserve gut integrity and functionality from stress-induced and inflammatory damage, thereby enforcing its potential as an effective probiotic strain.

Gut microbiota derived metabolites contribute to intestinal barrier maturation at the suckling-to-weaning transition.

In suckling mammals, the onset of solid food ingestion is coincident with the maturation of the gut barrier. This ontogenic process is driven by the colonization of the intestine by the microbiota. However, the mechanisms underlying the microbial regulation of the intestinal development in early life are not fully understood. Here, we studied the co-maturation of the microbiota (composition and metabolic activity) and of the gut barrier at the suckling-to-weaning transition by using a combination of experiments in vivo (suckling rabbit model), ex vivo (Ussing chambers) and in vitro (epithelial cell lines and organoids). The microbiota composition, its metabolic activity, para-cellular epithelial permeability and the gene expression of key components of the gut barrier shifted sharply at the onset of solid food ingestion in vivo, despite milk was still predominant in the diet at that time. We found that cecal content sterile supernatant (i.e. containing a mixture of metabolites) obtained after the onset of solid food ingestion accelerated the formation of the epithelial barrier in Caco-2 cells in vitro and our results suggested that these effects were driven by the bacterial metabolite butyrate. Moreover, the treatment of organoids with cecal content sterile supernatant partially replicated in vitro the effects of solid food ingestion on the epithelial barrier in vivo. Altogether, our results show that the metabolites produced by the microbiota at the onset of solid food ingestion contribute to the maturation of the gut barrier at the suckling-to-weaning transition. Targeting the gut microbiota metabolic activity during this key developmental window might therefore be a promising strategy to promote intestinal homeostasis.

The multicomponent medication Spascupreel attenuates stress-induced gut dysfunction in rats.

BACKGROUND: Irritable bowel syndrome (IBS) is a common disorder worldwide. It is characterized by abdominal pain/discomfort and changes in bowel habits. Due to the multifactorial pathophysiology and the heterogeneity of IBS patients, appropriate treatment of IBS is still a challenge. Spascupreel (SP-11), as a multicomponent medication, has the potential to modulate multiple pathophysiological pathways simultaneously. Therefore, the objective of the current study was to investigate the effects of oral SP-11 treatment on stress-induced changes of peripheral and central functions in a rat model mimicking human IBS. METHODS: Naïve Wistar rats were treated with SP-11 (0.9 tab/kg) or NaCl 0.9% by oral gavage for 4 days before 2-hour partial restraint stress (PRS) procedure. Twenty minutes after PRS, central and peripheral stress-induced changes affecting IBS were assessed. These include the hypothalamic-pituitary-adrenal (HPA) axis response through plasma ACTH and corticosterone measurements, visceral pain in response to colorectal distension, gut permeability, colonic mast cell number, and sensitization as well as gut transit time. RESULTS: Treatment with SP-11 reduced the HPA axis activation in response to PRS. At the gut level, a reduction in colonic hypersensitivity to colorectal distension, a normalization of gut transit time acceleration, a reduced mast cell sensitization, and a trend toward reduced gut hyperpermeability were observed. CONCLUSIONS: These data suggest that stress-induced IBS signs can be reduced using SP-11 in rats. The observed effects and the good tolerability of the drug make SP-11 an innovative candidate in the management of IBS.

Lactose and Fructo-oligosaccharides Increase Visceral Sensitivity in Mice via Glycation Processes, Increasing Mast Cell Density in Colonic Mucosa.

BACKGROUND & AIMS: Irritable bowel syndrome (IBS) is characterized by abdominal pain, bloating, and erratic bowel habits. A diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) can reduce symptoms of IBS, possibly by reducing microbial fermentation products. We investigated whether ingestion of FODMAPs can induce IBS-like visceral hypersensitivity mediated by fermentation products of intestinal microbes in mice. METHODS: C57Bl/6 mice were gavaged with lactose, with or without the antiglycation agent pyridoxamine, or saline (controls) daily for 3 weeks. A separate group of mice were fed a diet containing fructo-oligosaccharides, with or without pyridoxamine in drinking water, or a normal chow diet (controls) for 6 weeks. Feces were collected and analyzed by 16S ribosomal RNA gene sequencing and bacterial community analyses. Abdominal sensitivity was measured by electromyography and mechanical von Frey filament assays. Colon tissues were collected from some mice and analyzed by histology and immunofluorescence to quantify mast cells and expression of advanced glycosylation end-product specific receptor (AGER). RESULTS: Mice gavaged with lactose or fed fructo-oligosaccharides had increased abdominal sensitivity compared with controls, associated with increased numbers of mast cells in colon and expression of the receptor for AGER in proximal colon epithelium. These effects were prevented by administration of pyridoxamine. Lactose and/or pyridoxamine did not induce significant alterations in the composition of the fecal microbiota. Mass spectrometric analysis of carbonyl compounds in fecal samples identified signatures associated with mice given lactose or fructo-oligosaccharides vs controls. CONCLUSIONS: We found that oral administration of lactose or fructo-oligosaccharides to mice increases abdominal sensitivity, associated with increased numbers of mast cells in colon and expression of AGER; these can be prevented with an antiglycation agent. Lactose and/or pyridoxamine did not produce alterations in fecal microbiota of mice. Our findings indicate that preventing glycation reactions might reduce abdominal pain in patients with IBS with sensitivity to FODMAPs.

Colonic mast cell numbers, symptom profile, and mucosal expression of elements of the epithelial barrier in irritable bowel syndrome.

BACKGROUND: This study aimed to determine whether patients with IBS displayed altered mucosal mast cell (MC) numbers and proportions of MCs co-localizing with nerves compared with healthy subjects (HS) and whether these MC characteristics correlated with IBS symptoms, elements of the epithelial barrier, or visceral sensitivity. METHODS: Mucosal MC characteristics were determined using immunoassay. IBS symptoms, gene expression of elements of the epithelial barrier, fecal serine protease activity, and visceral sensitivity were assessed. KEY RESULTS: The MC numbers per mm2 were 2.0 (0.0-6.0) in patients with IBS (n = 43) and 3.5 (1.1-9.1) in HS (n = 20, P = .26). Of these, MCs were 0.0 (0.0-20) % vs 3.1 (0.0-18) % (P = .76) in IBS and HS, respectively, in co-localization with nerve fibers. MC characteristics were equivalent in the different IBS subtypes. Hierarchical cluster analysis identified two distinct groups among patients with IBS: MC high (higher MC numbers and proportions of MCs co-localizing with nerves) and MC low (lower MC numbers and proportions of MCs co-localizing with nerves). The MC high and MC low groups could not be discriminated with regard to IBS symptoms, parameters of visceral sensitivity, gene expression of elements of the epithelial barrier, and fecal protease activity. CONCLUSION AND INFERENCES: There was no evidence of increased infiltration or altered localization of MCs in the colonic mucosa of patients with IBS. These MC characteristics were not linked to global IBS symptoms or mucosal expression of elements of the epithelial barrier. These findings indicate that quantity and location of mucosal MCs are factors not involved in the pathophysiology of IBS.

Effects of thermized donkey milk with lysozyme activity on altered gut barrier in mice exposed to water-avoidance stress.

Nutrition plays a crucial role in human gut health through the improvement of gut barrier functionality. Donkey milk represents an interesting source of natural antimicrobial factors such as lysozyme. Recently, anti-inflammatory properties of donkey milk lysozyme activity were described in a mouse model of ileitis. The current increase of donkey milk consumption highlights the necessity to propose a healthy milk compliant with microbiological standards. This study aims to define a heat treatment of donkey milk, retaining its high lysozyme activity, and to evaluate its beneficial effects on a gut barrier impairment model due to chronic stress in mice. To perform this experiment, samples of raw donkey milk were collected in 15 distinct French farms. Microbiological analysis and lysozyme content and activity were evaluated for each sample. Then, several heat treatments were carried out to define a time and temperature combination that allowed for both a reduction in the number of total micro-organisms, increasing the shelf-life of the product, and preservation of lysozyme activity. The beneficial effect of heated donkey milk on the gut barrier of mice was evaluated and compared with raw donkey milk. We found that samples of raw donkey milk showed low total mesophilic microbial counts, and no pathogens were detected. Among the different heat-treatment procedures tested, a 2-min, 72°C combination was determined to be the most optimal time and temperature combination to preserve lysozyme activity and increase the shelf-life of donkey milk. Oral administration of this heat-treated donkey milk in mice counteracted chronic stress-induced intestinal damage, illustrated by gut hyper-permeability and low-grade inflammation, similar to raw donkey milk. We have demonstrated for the first time that oral intervention with donkey milk, optimally heat-treated to retain enzymatic lysozyme activity, improves intestinal barrier damage linked to psychological stress in mice.

5-oxoETE triggers nociception in constipation-predominant irritable bowel syndrome through MAS-related G protein-coupled receptor D.

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder that is characterized by chronic abdominal pain concurrent with altered bowel habit. Polyunsaturated fatty acid (PUFA) metabolites are increased in abundance in IBS and are implicated in the alteration of sensation to mechanical stimuli, which is defined as visceral hypersensitivity. We sought to quantify PUFA metabolites in patients with IBS and evaluate their role in pain. Quantification of PUFA metabolites by mass spectrometry in colonic biopsies showed an increased abundance of 5-oxoeicosatetraenoic acid (5-oxoETE) only in biopsies taken from patients with IBS with predominant constipation (IBS-C). Local administration of 5-oxoETE to mice induced somatic and visceral hypersensitivity to mechanical stimuli without causing tissue inflammation. We found that 5-oxoETE directly acted on both human and mouse sensory neurons as shown by lumbar splanchnic nerve recordings and Ca2+ imaging of dorsal root ganglion (DRG) neurons. We showed that 5-oxoETE selectively stimulated nonpeptidergic, isolectin B4 (IB4)-positive DRG neurons through a phospholipase C (PLC)- and pertussis toxin-dependent mechanism, suggesting that the effect was mediated by a G protein-coupled receptor (GPCR). The MAS-related GPCR D (Mrgprd) was found in mouse colonic DRG afferents and was identified as being implicated in the noxious effects of 5-oxoETE. Together, these data suggest that 5-oxoETE, a potential biomarker of IBS-C, induces somatic and visceral hyperalgesia without inflammation in an Mrgprd-dependent manner. Thus, 5-oxoETE may play a pivotal role in the abdominal pain associated with IBS-C.

Oral treatment with plecanatide or dolcanatide attenuates visceral hypersensitivity via activation of guanylate cyclase-C in rat models.

AIM: To investigate the effects of plecanatide and dolcanatide on maintenance of paracellular permeability, integrity of tight junctions and on suppression of visceral hypersensitivity. METHODS: Transport of fluorescein isothiocyanate (FITC)-dextran was measured to assess permeability across cell monolayers and rat colon tissues. Effects of plecanatide and dolcanatide on the integrity of tight junctions in Caco-2 and T84 monolayers and on the expression and localization of occludin and zonula occludens-1 (ZO-1) were examined by immunofluorescence microscopy. Anti-nociceptive activity of these agonists was evaluated in trinitrobenzene sulfonic acid (TNBS)-induced inflammatory as well as in non-inflammatory partial restraint stress (PRS) rat models. Statistical significance between the treatment groups in the permeability studies were evaluated using unpaired t-tests. RESULTS: Treatment of T84 and Caco-2 monolayers with lipopolysaccharide (LPS) rapidly increased permeability, which was effectively suppressed when monolayers were also treated with plecanatide or dolcanatide. Similarly, when T84 and Caco-2 monolayers were treated with LPS, cell surface localization of tight junction proteins occludin and ZO-1 was severely disrupted. When cell monolayers were treated with LPS in the presence of plecanatide or dolcanatide, occludin and ZO-1 were localized at the cell surface of adjoining cells, similar to that observed for vehicle treated cells. Treatment of cell monolayers with plecanatide or dolcanatide without LPS did not alter permeability, integrity of tight junctions and cell surface localization of either of the tight junction proteins. In rat visceral hypersensitivity models, both agonists suppressed the TNBS-induced increase in abdominal contractions in response to colorectal distension without affecting the colonic wall elasticity, and both agonists also reduced colonic hypersensitivity in the PRS model. CONCLUSION: Our results suggest that activation of GC-C signaling might be involved in maintenance of barrier function, possibly through regulating normal localization of tight junction proteins. Consistent with these findings, plecanatide and dolcanatide showed potent anti-nociceptive activity in rat visceral hypersensitivity models. These results imply that activation of GC-C signaling may be an attractive therapeutic approach to treat functional constipation disorders and inflammatory gastrointestinal conditions.

The role of mucoprotectants in the management of gastrointestinal disorders.

INTRODUCTION: The intestinal barrier controls the absorption of nutrients and water whilst helping to prevent the entry of toxins and pathogenic micro-organisms from the lumen into the tissues. Deficiencies in the barrier are associated with various gastrointestinal and extra digestive disorders. Areas covered: This review provides an overview of the relationship between increased intestinal permeability and disease, and considers the role of mucosal protectants (mucoprotectants) in restoring normal intestinal barrier function, with a particular focus on diarrheal disorders. Expert commentary: Impairment of the intestinal barrier characterizes a variety of diseases, and there is ongoing interest in the development of pharmacological approaches targeting the reduction of intestinal permeability. These include corticosteroids, aminosalicylates and anti-tumor necrosis factor-α (TNF-α), which act by reducing inflammation; probiotics, which modulate the production of mucin and epithelial tight junction proteins; and mucoprotectants, which form a protective film over the epithelium. Recently, preclinical and clinical data highlight, the ability of new mucoprotectants, such as gelatin tannate and xyloglucan, to protect the intestinal mucosa and to exert anti-diarrheal effects. In the future the ability of these substances to enhance the intestinal barrier may extend their use in the management of a variety of gastro-intestinal diseases associated with 'leaky gut'.

Donkey milk consumption exerts anti-inflammatory properties by normalizing antimicrobial peptides levels in Paneth's cells in a model of ileitis in mice.

PURPOSE: In this study, we showed the beneficial effects of donkey milk (DM) on inflammatory damages, endogenous antimicrobial peptides levels and fecal microbiota profile in a mice model of Crohn's disease. Nowadays, new strategies of microbiome manipulations are on the light involving specific diets to induce and/or to maintain clinical remission. Interest of DM is explained by its high levels of antimicrobial peptides which confer it anti-inflammatory properties. METHODS: C57BL/6 mice were orally administered with or without indomethacin for 5 days and co-treated with vehicle, DM or heated DM during 7 days. Intestinal length and macroscopic damage scores (MDSs) were determined; ileal samples were taken off for microscopic damage (MD), lysozyme immunostaining and mRNA α-defensin assessments. Ileal luminal content and fecal pellets were collected for lysozyme enzymatic activity and lipocalin-2 (LCN-2) evaluations. Fecal microbiota profiles were compared using a real-time quantitative PCR-based analysis. RESULTS: Administration of indomethacin caused an ileitis in mice characterized by (1) a decrease in body weight and intestinal length, (2) a significant increase in MDS, MD and LCN-2, (3) a reduction in both α-defensin mRNA expression and lysozyme levels in Paneth's cells reflected by a decrease in lysozyme activity in feces, and (4) a global change in relative abundance of targeted microbial communities. DM treatment significantly reduced almost of all these ileitis damages, whereas heated DM has no impact on ileitis. CONCLUSIONS: DM consumption exerts anti-inflammatory properties in mice by restoring the endogenous levels of antimicrobial peptides which contribute in turn to reduce microbiota imbalance.

Evaluation of reticulated gelatin-hibiscus-propolis against intestinal commensal species commonly associated with urinary tract infections.

AIM: Reticulated gelatin (RG), hibiscus and propolis (RGHP) is a medical device that can reduce the bacterial adherence to epithelial cultured cells and invasion by enteropathogens, thus gathering relevant properties to decrease the risk of urinary tract infections (UTIs). We aimed at evaluating in Wistar rats the efficacy of RGHP, RG and vehicle against intestinal commensals commonly involved in UTIs. METHODS: Animals received orally (with supplemental Na2CO3): RGHP 1540 mg/day/rat; RG 500 mg/day/rat or vehicle. RESULTS: RGHP significantly reduced fecal Escherichia coli and Enterococcus spp. levels without affecting other targeted Enterobacteriaceae. The antagonistic property of RGHP was confirmed in streptomycin-pretreated rats highly colonized with a human commensal E. coli strain with uropathogenic potential. CONCLUSION: RGHP may decrease the risk of UTIs by reducing colonization by opportunistic uropathogens.