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.

Effects of sodium nitrite reduction, removal or replacement on cured and cooked meat for microbiological growth, food safety, colon ecosystem, and colorectal carcinogenesis in Fischer 344 rats.

Epidemiological and experimental evidence indicated that processed meat consumption is associated with colorectal cancer risks. Several studies suggest the involvement of nitrite or nitrate additives via N-nitroso-compound formation (NOCs). Compared to the reference level (120 mg/kg of ham), sodium nitrite removal and reduction (90 mg/kg) similarly decreased preneoplastic lesions in F344 rats, but only reduction had an inhibitory effect on Listeria monocytogenes growth comparable to that obtained using the reference nitrite level and an effective lipid peroxidation control. Among the three nitrite salt alternatives tested, none of them led to a significant gain when compared to the reference level: vegetable stock, due to nitrate presence, was very similar to this reference nitrite level, yeast extract induced a strong luminal peroxidation and no decrease in preneoplastic lesions in rats despite the absence of NOCs, and polyphenol rich extract induced the clearest downward trend on preneoplastic lesions in rats but the concomitant presence of nitrosyl iron in feces. Except the vegetable stock, other alternatives were less efficient than sodium nitrite in reducing L. monocytogenes growth.

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.

Maternal heme-enriched diet promotes a gut pro-oxidative status associated with microbiota alteration, gut leakiness and glucose intolerance in mice offspring.

Maternal environment, including nutrition and microbiota, plays a critical role in determining offspring's risk of chronic diseases such as diabetes later in life. Heme iron requirement is amplified during pregnancy and lactation, while excessive dietary heme iron intake, compared to non-heme iron, has shown to trigger acute oxidative stress in the gut resulting from reactive aldehyde formation in conjunction with microbiota reshape. Given the immaturity of the antioxidant defense system in early life, we investigated the extent to which a maternal diet enriched with heme iron may have a lasting impact on gut homeostasis and glucose metabolism in 60-day-old C3H/HeN mice offspring. As hypothesized, the form of iron added to the maternal diet differentially governed the offspring's microbiota establishment despite identical fecal iron status in the offspring. Importantly, despite female offspring was unaffected, oxidative stress markers were however higher in the gut of male offspring from heme enriched-fed mothers, and were accompanied by increases in fecal lipocalin-2, intestinal para-cellular permeability and TNF-α expression. In addition, male mice displayed blood glucose intolerance resulting from impaired insulin secretion following oral glucose challenge. Using an integrated approach including an aldehydomic analysis, this male-specific phenotype was further characterized and revealed close covariations between unidentified putative reactive aldehydes and bacterial communities belonging to Bacteroidales and Lachnospirales orders. Our work highlights how the form of dietary iron in the maternal diet can dictate the oxidative status in gut offspring in a sex-dependent manner, and how a gut microbiota-driven oxidative challenge in early life can be associated with gut barrier defects and glucose metabolism disorders that may be predictive of diabetes development.

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.

Revisiting definition and assessment of intestinal trans-epithelial passage.

This study aims to remind that Intestinal Passage (IP) measurement is a complex task that cannot be achieved by a unique measure of an orally given exogenous marker in blood or urine. This will be illustrated in the case of NOD mice. Indeed, various methods have been proposed to measure IP. Among them ex vivo measurement in Ussing chambers of luminal to serosal fluxes of exogenous markers and in vivo measurement of exogenous markers in blood or urine after oral gavage are the more commonly used. Even though they are commonly used indifferently, they do not give the same information and can provide contradictory results. Published data showed that diabetic status in female Non Obese Diabetic (NOD) mice increased FD4 concentration in blood after gavage but did not modify FD4 fluxes in Ussing chamber. We observed the same results in our experimental conditions and tracked FD4 concentrations in blood over a kinetic study (Area Under the Curve-AUC). In vivo measurements are a dynamic process and address not only absorption (IP and intestinal surface) but also distribution, metabolism and excretion (ADME). Diabetic status in NOD mice was associated with an increase of intestinal length (absorptive surface), itself positively correlated with AUC of FD4 in blood. We concluded that increased intestinal length induced by diabetic status will extend the absorptive surface and increase FD4 concentration in plasma (in vivo measurement) despite no modification on IP of FD4 (ex vivo measurement). In addition, this study characterized intestinal function in diabetic NOD mice. Diabetic status in NOD female mice increases intestinal length and decreases paracellular IP (FSS) without affecting transcellular IP (HRP, FD4). Histological studies of small and large intestine did not show any modification of intestinal circumference nor villi and crypt size. Finally, diabetic status was not associated with intestinal inflammation (ELISA).

The pregnane X receptor drives sexually dimorphic hepatic changes in lipid and xenobiotic metabolism in response to gut microbiota in mice.

BACKGROUND: The gut microbiota-intestine-liver relationship is emerging as an important factor in multiple hepatic pathologies, but the hepatic sensors and effectors of microbial signals are not well defined. RESULTS: By comparing publicly available liver transcriptomics data from conventional vs. germ-free mice, we identified pregnane X receptor (PXR, NR1I2) transcriptional activity as strongly affected by the absence of gut microbes. Microbiota depletion using antibiotics in Pxr+/+ vs Pxr-/- C57BL/6J littermate mice followed by hepatic transcriptomics revealed that most microbiota-sensitive genes were PXR-dependent in the liver in males, but not in females. Pathway enrichment analysis suggested that microbiota-PXR interaction controlled fatty acid and xenobiotic metabolism. We confirmed that antibiotic treatment reduced liver triglyceride content and hampered xenobiotic metabolism in the liver from Pxr+/+ but not Pxr-/- male mice. CONCLUSIONS: These findings identify PXR as a hepatic effector of microbiota-derived signals that regulate the host's sexually dimorphic lipid and xenobiotic metabolisms in the liver. Thus, our results reveal a potential new mechanism for unexpected drug-drug or food-drug interactions. Video abstract.

Anxiety is a potential effect modifier of the association between red and processed meat consumption and cancer risk: findings from the NutriNet-Santé cohort.

PURPOSE: Red and processed meats are recognized by the International Agency for Research on Cancer as probably carcinogenic and carcinogenic to humans, respectively. Heme iron has been proposed as a central factor responsible for this effect. Furthermore, anxiety affects the intestinal barrier function by increasing intestinal permeability. The objective of this work was to assess how anxiety modifies the association between red and processed meat consumption and cancer risk in the NutriNet-Santé prospective cohort (2009-2019). METHODS: Using multi-adjusted Cox models in a sample of 101,269 subjects, we studied the associations between the consumption of red and processed meat, the amount of heme iron coming from these meats and overall, colorectal, prostate, and breast cancer risks, overall and separately among participants with and without anxiety. RESULTS: An increase in red and processed meat consumption was associated with an increased risk of developing colorectal cancer in the total population (HR for an increase of 50 g/day = 1.18 (1.01-1.37), p = 0.03). After stratification on anxiety, the HR 50 g/day was 1.42 (1.03-1.94, p = 0.03) in anxious participants and 1.12 (0.94-1.33, p = 0.20) in other participants. Similar trends were observed for overall cancer risk. Analyses conducted with heme iron also provided similar results. CONCLUSIONS: Our results strengthen the existing body of evidence supporting that red and processed meat consumption and heme iron intake are associated with an increased risk of overall and more specifically colorectal cancer, and suggest that anxiety modifies these associations, with an increased risk in anxious participants.

Repeated exposure of Caco-2 versus Caco-2/HT29-MTX intestinal cell models to (nano)silver in vitro: Comparison of two commercially available colloidal silver products.

Colloidal silver products are sold for a wide range of disinfectant and health applications. This has increased the potential for human exposure to silver nanoparticles (AgNPs) and ions (Ag+), for which oral ingestion is considered to be a major route of exposure. Our objective was to evaluate and compare the toxicity of two commercially available colloidal silver products on two human intestinal epithelial models under realistic exposure conditions. Mesosilver™ and AgC were characterized and a concentration range between 0.1 and 12 µg/mL chosen. Caco-2 cells vs. co-culture of Caco-2 and mucus-secreting HT29-MTX cells (90/10) were used. Repeated exposure was carried out to determine cell viability over 18 days of cell differentiation in 24-well plates. Selected concentrations (0.1, 1, and 3 µg/mL) were tested on cells cultured in E-plates and Transwells with the same repeated exposure regimen, to determine cell impedance, and cell viability and trans-epithelial electrical resistance (TEER), respectively. Silver uptake, intracellular localisation, and translocation were determined by CytoViva™, HIM-SIMS, and ICP-MS. Genotoxicity was determined on acutely-exposed proliferating Caco-2 cells by γH2AX immunofluorescence staining. Repeated exposure of a given concentration of AgC, which is composed solely of ionic silver, generally exerted more toxic effects on Caco-2 cells than Mesosilver™, which contains a mix of AgNPs and ionic silver. Due to its patchy structure, the presence of mucus in the Caco-2/HT29-MTX co-culture only slightly mitigated the deleterious effects on cell viability. Increased genotoxicity was observed for AgC on proliferating Caco-2 cells. Silver uptake, intracellular localisation, and translocation were similar. In conclusion, Mesosilver™ and AgC colloidal silver products show different levels of gut toxicity due to the forms of distinct silver (AgNPs and/or Ag+) contained within. This study highlights the applicability of high-resolution (chemical) imaging to detect and localize silver and provides insights into its uptake mechanisms, intracellular fate and cellular effects.

Heme-Iron-Induced Production of 4-Hydroxynonenal in Intestinal Lumen May Have Extra-Intestinal Consequences through Protein-Adduct Formation.

Some epidemiological studies show that heme iron consumption, in red meat, is associated to the development of several chronic diseases, including cancers and cardio-metabolic diseases. As heme iron intestinal absorption is finely regulated, we hypothesized that heme iron may act indirectly, through the peroxidation of dietary lipids, in food or in the intestinal lumen during digestion. This heme-iron-induced lipid peroxidation provokes the generation of toxic lipid oxidation products that could be absorbed, such as 4-hydroxynonenal (HNE). In a first experiment, heme iron given to rats by oral gavage together with the linoleic-acid-rich safflower oil induced the formation of HNE in the intestinal lumen. The HNE major urinary metabolite was elevated in the urine of the treated rats, indicating that this compound has been absorbed. In a second experiment, we showed that stable isotope-labeled HNE given orally to rats was able to reach non-intestinal tissues as a bioactive form and to make protein-adducts in heart, liver and skeletal muscle tissues. The presence of HNE-protein adducts in those tissues suggests a putative biological role of diet-originating HNE in extra-intestinal organs. This finding could have major consequences on the onset/development of chronic diseases associated with red meat over-consumption, and more largely to peroxidation-prone food consumption.

The food contaminant, deoxynivalenol, modulates the Thelper/Treg balance and increases inflammatory bowel diseases.

The incidence of inflammatory bowel diseases (IBD) is increasing in both Western and developing countries. IBD are multifactorial disorders involving complex interactions between genetic, immune, and environmental factors such as exposure to food contaminants. Deoxynivalenol (DON) is the most prevalent mycotoxin that contaminates staple food and induces intestinal breakdown and inflammatory response. To delineate the role of DON oral exposure in IBD, we used a Dextran sulfate sodium (DSS) colitis model in rats fed with a DON-contaminated diet or a control diet for 4 weeks. Colitis was induced in the 4th week by increasing concentrations of DSS in the drinking water (0, 2, 3 or 5%). DON exacerbated body weight loss and accelerated the appearance of symptoms in animals treated with DSS. DON increased morphological damage, pro-inflammatory markers (myeloperoxidase, CXCL-1 and IL-1ß) and immune cell responses. In lamina propria of the rat with colitis, DON increased adaptive and innate immune responses after anti-CD3/28 or LPS stimulation, respectively. In the spleen, DON increased IFNγ secretion and reduced Treg populations. Interestingly, De-epoxy-DON (DOM-1) a detoxified form of DON did not have any consequences on colitis. These results suggest that DON is a risk factor in the onset of IBD.

Jejunal villus absorption and paracellular tight junction permeability are major routes for early intestinal uptake of food-grade TiO2 particles: an in vivo and ex vivo study in mice.

BACKGROUND: Food-grade TiO2 (E171 in the EU) is widely used as a coloring agent in foodstuffs, including sweets. Chronic dietary exposure raises concerns for human health due to proinflammatory properties and the ability to induce and promote preneoplastic lesions in the rodent gut. Characterization of intestinal TiO2 uptake is essential for assessing the health risk in humans. We studied in vivo the gut absorption kinetics of TiO2 in fasted mice orally given a single dose (40 mg/kg) to assess the ability of intestinal apical surfaces to absorb particles when available without entrapment in the bolus. The epithelial translocation pathways were also identified ex vivo using intestinal loops in anesthetized mice. RESULTS: The absorption of TiO2 particles was analyzed in gut tissues by laser-reflective confocal microscopy and ICP-MS at 4 and 8 h following oral administration. A bimodal pattern was detected in the small intestine: TiO2 absorption peaked at 4 h in jejunal and ileal villi before returning to basal levels at 8 h, while being undetectable at 4 h but significantly present at 8 h in the jejunal Peyer's patches (PP). Lower absorption occurred in the colon, while TiO2 particles were clearly detectable by confocal microscopy in the blood at 4 and 8 h after treatment. Ex vivo, jejunal loops were exposed to the food additive in the presence and absence of pharmacological inhibitors of paracellular tight junction (TJ) permeability or of transcellular (endocytic) passage. Thirty minutes after E171 addition, TiO2 absorption by the jejunal villi was decreased by 66% (p < 0.001 vs. control) in the presence of the paracellular permeability blocker triaminopyrimidine; the other inhibitors had no significant effect. Substantial absorption through a goblet cell (GC)-associated pathway, insensitive to TJ blockade, was also detected. CONCLUSIONS: After a single E171 dose in mice, early intestinal uptake of TiO2 particles mainly occurred through the villi of the small intestine, which, in contrast to the PP, represent the main absorption surface in the small intestine. A GC-associated passage and passive diffusion through paracellular TJ spaces between enterocytes appeared to be major absorption routes for transepithelial uptake of dietary TiO2.

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.

Author Correction: Dimorphic metabolic and endocrine disorders in mice lacking the constitutive androstane receptor.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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.

Dimorphic metabolic and endocrine disorders in mice lacking the constitutive androstane receptor.

Metabolic diseases such as obesity, type II diabetes and hepatic steatosis are a public health concern in developed countries. The metabolic risk is gender-dependent. The constitutive androstane receptor (CAR), which is at the crossroads between energy metabolism and endocrinology, has recently emerged as a promising therapeutic agent for the treatment of obesity and type 2 diabetes. In this study we sought to determine its role in the dimorphic regulation of energy homeostasis. We tracked male and female WT and CAR deficient (CAR-/-) mice for over a year. During aging, CAR-/- male mice developed hypercortisism, obesity, glucose intolerance, insulin insensitivity, dyslipidemia and hepatic steatosis. Remarkably, the latter modifications were absent, or minor, in female CAR-/- mice. When ovariectomized, CAR-/- female mice developed identical patterns of metabolic disorders as observed in male mice. These results highlight the importance of steroid hormones in the regulation of energy metabolism by CAR. They unveil a sexually dimorphic role of CAR in the maintenance of endocrine and metabolic homeostasis underscoring the importance of considering sex in treatment of metabolic diseases.

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.

Pharmacological restoration of gut barrier function in stressed neonates partially reverses long-term alterations associated with maternal separation.

RATIONALE: Intestinal permeability plays an important role in gut-brain axis communication. Recent studies indicate that intestinal permeability increases in neonate pups during maternal separation (MS). OBJECTIVES: The present study aims to determine whether pharmacological inhibition of myosin light chain kinase (MLCK), which regulates tight junction contraction and controls intestinal permeability, in stressed neonates, protects against the long-term effects of MS. METHODS: Male Wistar rats were exposed to MS (3 h per day from post-natal day (PND)2 to PND14) or left undisturbed and received daily intraperitoneal injection of a MLCK inhibitor (ML-7, 5 mg/kg) or vehicle during the same period. At adulthood, emotional behaviors, corticosterone response to stress, and gut microbiota composition were analyzed. RESULTS: ML-7 restored gut barrier function in MS rats specifically during the neonatal period. Remarkably, ML-7 prevented MS-induced sexual reward-seeking impairment and reversed the alteration of corticosterone response to stress at adulthood. The effects of ML-7 were accompanied by the normalization of the abundance of members of Lachnospiraceae, Clostridiales, Desulfovibrio, Bacteroidales, Enterorhabdus, and Bifidobacterium in the feces of MS rats at adulthood. CONCLUSIONS: Altogether, our work suggests that improvement of intestinal barrier defects during development may alleviate some of the long-term effects of early-life stress and provides new insight on brain-gut axis communication in a context of stress.