Small Intestinal Permeability Research Articles

Relationship between Markers of Gut Barrier Function and Erythrocyte Membrane PUFAs in Diarrhea-Predominant IBS Patients Undergoing a Low-FODMAP Diet.

Many patients with irritable bowel syndrome (IBS) have a compromised intestinal barrier associated with low-grade inflammation. Polyunsaturated fatty acids (PUFAs) are potential mediators of inflammation: omega-6 PUFAs are pro-inflammatory, while omega-3 PUFAs are antioxidant and anti-inflammatory. Zonulin is a potential biomarker for small intestinal permeability (s-IP). This study investigated the relationship between PUFAs and gastrointestinal (GI) barrier integrity in IBS patients with predominant diarrhea (IBS-D). We evaluated GI barrier function indicators in the urine and bloodstream and erythrocyte membrane PUFA composition in 38 IBS-D patients (5 men, 33 women, 44.11 ± 1.64 years), categorized at baseline by fecal zonulin levels into high (≥107 ng/mL, H-FZ) and normal (<107 ng/mL N-FZ) groups. Evaluations were conducted prior to and following a 12-week diet low in FODMAPs (LFD). At baseline, H-FZ patients had s-IP significantly higher than the reference value, lower n-3 PUFAs levels, and higher n-6/n-3 PUFAs and arachidonic acid (AA) to eicosapentaenoic acid (EPA) ratios than N-FZ. After LFD, H-FZ patients showed significant increases in n-3 PUFAs levels; decreases in n-6 PUFAs, n-6/n-3 PUFAs and AA/EPA ratios; and improved s-IP. The n-6/n-3 PUFAs ratio positively correlated with fecal zonulin levels in all subjects. These findings highlight the relationship between PUFAs and the intestinal barrier, suggesting their role in IBS-D pathophysiology and confirming the positive effects of LFD in managing IBS-D.

Plasma, brain and spinal cord concentrations of caffeine are reduced in the SOD1G93A mouse model of amyotrophic lateral sclerosis following oral administration

Modifications to the small intestine and liver are known to occur during the symptomatic disease period of amyotrophic lateral sclerosis (ALS), a member of the motor neuron disease (MND) family of neurodegenerative disorders. How these modifications impact on oral absorption and pharmacokinetics of drugs remains unknown. In this study, model drugs representing different mechanisms of intestinal transport (caffeine for passive diffusion, digoxin for P-glycoprotein efflux, and sulfasalazine for breast cancer resistance protein efflux) were administered via oral gavage to postnatal day 114–120 male and female SOD1G93A mice (model of familial ALS) and wild-type (WT) littermates. Samples of blood, brain and spinal cord were taken at either 15, 30, 60 or 180 min after administration. In addition, the in vivo gastric emptying of 70 kDa fluorescein isothiocyanate-dextran (FITC-dextran) and the ex vivo intestinal permeability of caffeine were assessed. The area under the plasma concentration–time curves (AUCplasma) of digoxin and sulfasalazine were not significantly different between SOD1G93A and WT mice for both sexes. However, the AUCplasma of caffeine was significantly lower (female: 0.79-fold, male: 0.76-fold) in SOD1G93A compared to WT mice, which was associated with lower AUCbrain (female: 0.76-fold, male: 0.80-fold) and AUCspinal cord (female: 0.81-fold, male: 0.82-fold). The AUCstomach of caffeine was significantly higher (female: 1.5-fold, male: 1.9-fold) in SOD1G93A compared to WT mice, suggesting reduced gastric emptying in SOD1G93A mice. In addition, there was a significant reduction in gastric emptying of FITC-dextran (0.66-fold) and ex vivo intestinal permeability of caffeine (0.52-fold) in male SOD1G93A compared to WT mice. Reduced systemic and brain/spinal cord exposure of caffeine in SOD1G93A mice may therefore result from alterations to gastric emptying and small intestinal permeability. Specific dosing requirements may therefore be required for certain medicines in ALS to ensure that they remain in a safe and effective concentration range.

Dietary Milk Phospholipids Increase Body Fat and Modulate Gut Permeability, Systemic Inflammation, and Lipid Metabolism in Mice

The study aimed at how dietary milk polar lipids affect gut permeability, systemic inflammation, and lipid metabolism during diet-induced obesity (DIO). C57BL/6J mice (n = 6x3) were fed diets with 34% fat as energy for 15 weeks: (1) modified AIN-93G diet (CO); (2) CO with milk gangliosides (GG); (3) CO with milk phospholipids (MPL). Gut permeability was assessed by FITC-dextran and sugar absorption tests. Intestinal tight junction proteins were evaluated by Western blot. Plasma cytokines were measured by immunoassay. Body composition was assessed by magnetic resonance imaging. Tissue lipid profiles were obtained by thin layer chromatography. Hepatic expression of genes associated with lipid metabolism was assessed by RT-qPCR. MPL increased the efficiency of converting food into body fat and facilitated body fat accumulation compared with CO. MPL and GG did not affect fasting glucose or HOMA-IR during DIO. MPL increased while GG decreased plasma TG compared with CO. MPL decreased phospholipids subclasses in the muscle while increased those in the liver compared with CO. GG and MPL had little effect on hepatic expression of genes associated with lipid metabolism. Compared with CO, MPL decreased polar lipids content in colon mucosa. Small intestinal permeability decreased while colon permeability increased and then recovered during the feeding period. High-fat feeding increased plasma endotoxin after DIO but did not affect plasma cytokines. MPL and GG did not affect plasma endotoxin, adipokines and inflammatory cytokines. After the establishment of obesity, MPL increased gut permeability to large molecules but decreased intestinal absorption of small molecules while GG tended to have the opposite effects. MPL and GG decreased mannitol and sucralose excretions, which peaked at d 45 in the CO group. MPL decreased occludin in jejunum mucosa compared with CO. GG and MPL did not affect zonula occludens-1 in gut mucosa. In conclusion, during DIO, milk GG decreased gut permeability, and had little effect on systemic inflammation and lipid metabolism; MPL facilitated body fat accumulation, decreased gut permeability, did not affect systemic inflammation.

Development and validation of an LC-MS/MS method for the quantification of oral-sugar probes in plasma to test small intestinal permeability and absorptive capacity in the domestic cat (Felis catus)

A novel method for quantifying the concentration of lactulose, rhamnose, xylose, and 3-O-methylglucose (3-OMG) in cat plasma using liquid chromatography-mass spectrometry (LC-MS) was developed. Domestic male cats (n = 13) were orally dosed with a solution containing the four sugars to test the permeability and absorptive capacity of their intestinal barrier. Plasma samples were taken 3 h later and were prepared with acetonitrile (ACN), dried under N2, and reconstituted in 90 % ACN with 1 mM ammonium formate. Stable isotope labelled 13C standards for each analyte were used as internal standards. Chromatographic separation was conducted using a Phenomenex Luna NH2 column with a gradient elution system of deionized water and 90 % ACN with 1 mM ammonium formate at 300 µL/min for 13 min total analysis time. Recovery trials were conducted in triplicate over three days with RSD values (%) for each day ranging from 1.2 to 1.4 for lactulose, 5.4 – 6.0 for rhamnose, 3.3 – 5.5 for xylose, and 2.6 – 5.6 for 3-OMG. Inter-day variations for each analyte were not different (p > 0.05). Limit of detection and quantification were 0.2 and 0.7 µg/mL for lactulose, 0.8 and 2.4 µg/mL for rhamnose, 0.6 and 1.8 µg/mL for xylose, and 0.3 and 1.1 µg/mL for 3-OMG, respectively. Plasma sugar concentrations recovered from cats were above the limit of quantification and below the highest calibration standard, validating the use of this method to test intestinal permeability and absorptive capacity in cats.

The type of fatty acid dictates their impact on gut permeability and nutrient absorption

We showed that short- and long-term (3 to 12 weeks) high-fat diet (HFD) feeding reduced protein expression of nutrient transporters in the proximal jejunum of mice. The most abundant fatty acids (FA) in HFD were oleic (OA), palmitic (PA) and stearic (EA) acid. Because PA and EA are generally regarded as pro-inflammatory, we hypothesize that dietary PA and EA alter gut permeability and absorption via inflammatory activation. To test this hypothesis, we orally administered HFD-matched doses of OA, PA, and EA to male C57BL/6 mice, fed on purified diet control (LFD), for 3 weeks. Food intake and body weight were monitored, and composition were also evaluated. We next qPCR-assessed the mRNA expression of cytokines ( TNF-α, IL-6, IL-1β, IFN-γ, IL-10) and inflammatory signaling transducers ( MD-2 and Myd88) as well as the protein content of nutrient transporters (Glut2, Pept1, Fat/cd36 and Npc1l1) and cell-cell adhesion proteins (Occludin) in the gut. Small intestinal permeability was assessed ex vivo and gut morphology was histologically determined. In addition, Caco-2 enterocytes were used to assess the impact of specific cytokines on nutrient transport and gut barrier integrity. All dietary FA reduced food intake without affecting lean or fat mass. In the jejunum, OA increased TNF-α gene expression whereas PA upregulated IFN-γ and MD-2 gene expression. Furthermore, OA reduced the nutrient transporters Glut2, Pept1, and Fat/cd36 without affecting Npc1l1, whereas PA and EA reduced Occludin protein content. PA, but not OA and EA, increased jejunum paracellular permeability ex vivo and increased villus length. In Caco-2 cells, while Tnf-α did not affect Glut2, Pept1 and Fat/cd36 or Npc1l1 content, Ifn-γ downregulated Occludin protein content. We conclude that OA and, more potently, PA exert inflammatory effects which contribute to damage gut barrier integrity and downregulate nutrient absorption. Our data point to IFN-γ as a main player coupling dietary stress from PA to altered gut homeostasis. Funding: FAPESP (grants number: 2014/12871-9, 2019/05086-7, 2020/12201-4, and 2022/14545). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Associations between various markers of intestinal barrier and immune function after a high-intensity exercise challenge.

Strenuous exercise can result in disruption of intestinal barrier function and occurrence of gastrointestinal symptoms. The aim of this exploratory study was to elucidate systemic effects of increased intestinal permeability after high-intensity exercise. Forty-one endurance-trained subjects performed a 60-min treadmill run at 80% VO2max. Small intestinal permeability was measured as urinary excretion ratio of lactulose/rhamnose (L/R). Blood, saliva and feces were analyzed for gut barrier and immune-related biomarkers. The exercise challenge increased several markers of intestinal barrier disruption, immune function and oxidative stress. We found a negative correlation between L/R ratio and uric acid (r = -0.480), as well as a positive correlation between the L/R ratio and fecal chromogranin A in male participants (r = 0.555). No significant correlations were found between any of the markers and gastrointestinal symptoms, however, perceived exertion correlated with the combination of IL-6, IL-10 and salivary cortisol (r = 0.492). The lack of correlation between intestinal permeability and gastrointestinal symptoms could be due to minor symptoms experienced in lab settings compared to real-life competitions. The correlation between L/R ratio and uric acid might imply a barrier-protective effect of uric acid, and inflammatory processes due to strenuous exercise seem to play an important role regarding physical exhaustion.

Bifidobacterium bifidum inhibits the TNF-α induced increase in intestinal epithelial tight junction permeability via a TLR-2/TLR-6 and PPAR-γ dependent inhibition of NF-κB p50/p65

Background: Bifidobacterium bifidum (BB) is one of the most widely used probiotic bacterial species and BB has been shown to have a protective effect against intestinal inflammation by an enhancement of the intestinal epithelial tight junction (TJ) barrier. Previous studies from our laboratory showed that a specific BB strain, referred to as BB1, caused a marked enhancement of intestinal epithelial TJ barrier, while strain BB4 had no effect. TNF-α contributes to the development of intestinal inflammation in inflammatory conditions of the gut, in part by increasing intestinal permeability and antigenic penetration. TNF-α induced increase in intestinal epithelial TJ permeability is mediated by an NF-κB p50/p65 activation of myosin light chain kinase (MLCK) gene and MLCK-induced opening of the intestinal TJ barrier. Peroxisome proliferator-activated receptor gamma (PPAR-γ) is an important nuclear receptor known to have anti-inflammatory activity by interfering with NF-κB activation. However, the protective effect of BB1 against TNF-α induced increase in intestinal TJ permeability remain unclear. Aims: The major purpose of this study was to delineate the protective effect of BB1 against the TNF-α induced increase in intestinal TJ permeability and to elucidate the intracellular mechanism involved. Methods: Filter-grown Caco-2 monolayers ( in vitro) and recycling intestinal perfusion of live mice ( in vivo) were the model systems used to assess intestinal TJ permeability. Results: 1) TNF-α caused an increase Caco-2 TJ permeability, as assed by Caco-2 trans-epithelial resistance (TER) and trans-epithelial flux of paracellular marker, FITC-Dextran 10kD. 2) Addition of BB1 (1x108 CFU/ml) to the apical membrane compartment inhibited the TNF-α increase in Caco-2 epithelial TJ permeability, while strain BB4 had no effect. 3) BB1 but not BB4, caused an increase in Caco-2 TLR-2 expression on the apical membrane surface, and siRNA induced knockdown of TLR-2 prevent the BB1 inhibition of TNF-α induced increase in Caco-2 TJ permeability. 4) TNF-α caused a rapid phosphorylation and degradation of Caco-2 IKK-α, as well as and phosphorylation and nuclear translocation of NF-κB p50/p65, indicating NF-κB activation. BB1, but not BB4, inhibited the NF-κB activation. 5) TNF-α activation of NF-κB was associated with an increase in MLCK gene (increase in MLCK promoter activity and mRNA transcription) and kinase activity. BB1, but not BB4, inhibited the TNF-α induced increase in MLCK gene and kinase activity. 6) BB1 but not BB4, caused a rapid PPAR-γ activation (PPAR-γ phosphorylation and nuclear translocation), and siRNA induced knockdown of PPAR-γ inhibited the TNF-α induced activation of NF-κB and increase in Caco-2 TJ permeability. 7) Intraperitoneal injection of TNF-α (5 mg) also caused time-dependent increase in mouse small intestinal permeability (IP) to FITC-Dextran 10kD. TNF-α caused a degradation of IkB-α in intestinal tissue and nuclear translocation of NF-kB in mouse enterocyte. 8) BB1, but not BB4, selectively activated PPAR-γ in mouse enterocytes and inhibited the TNF-α-induced activation of NF-κB, resulting in a decrease in mouse IP. 9) BB1 inhibition of TNF-α activation of mouse enterocyte NF-κB and increase in IP was prevented in mice with intestinal epithelial cell-specific knockout of PPAR-γ Villin-cre and TLR-2 Villin-cre mice. Conclusion: BB1 protects against the TNF-α induced increase in intestinal TJ permeability in a strain-specific manner. BB1 protects against the TNF-α induced increase in intestinal TJ permeability via a novel intracellular mechanism involving BB1/TLR-2 pathway activation of PPAR-γ, and PPAR-γ mediated inhibition of NF-κB p50/p65 and MLCK gene in enterocyte. This research project was supported by the National Institute of Diabetes and Digestive and Kidney Diseases R01-DK-121073-01. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Modulation of intestinal epithelial permeability by chronic small intestinal helminth infections.

Increased permeability of the intestinal epithelial layer is linked to the pathogenesis and perpetuation of a wide range of intestinal and extra-intestinal diseases. Infecting humans with controlled doses of helminths, such as human hookworm (termed hookworm therapy), is proposed as a treatment for many of the same diseases. Helminths induce immunoregulatory changes in their host which could decrease epithelial permeability, which is highlighted as a potential mechanism through which helminths treat disease. Despite this, the influence of a chronic helminth infection on epithelial permeability remains unclear. This study uses the chronically infecting intestinal helminth Heligmosomoides polygyrus to reveal alterations in the expression of intestinal tight junction proteins and epithelial permeability during the infection course. In the acute infection phase (1 week postinfection), an increase in intestinal epithelial permeability is observed. Consistent with this finding, jejunal claudin-2 is upregulated and tricellulin is downregulated. By contrast, in the chronic infection phase (6 weeks postinfection), colonic claudin-1 is upregulated and epithelial permeability decreases. Importantly, this study also investigates changes in epithelial permeability in a small human cohort experimentally challenged with the human hookworm, Necator americanus. It demonstrates a trend toward small intestinal permeability increasing in the acute infection phase (8 weeks postinfection), and colonic and whole gut permeability decreasing in the chronic infection phase (24 weeks postinfection), suggesting a conserved epithelial response between humans and mice. In summary, our findings demonstrate dynamic changes in epithelial permeability during a chronic helminth infection and provide another plausible mechanism by which chronic helminth infections could be utilized to treat disease.

Correlation of Differentially Expressed lncRNAs with Intestinal Flora Imbalance, Small Intestinal Permeability, and Glucose Uptake in T2DM Mice.

Diabetes is a major global health concern. This study aimed to investigate the correlation between differentially expressed lncRNAs in mice with type 2 diabetes mellitus (T2DM) and alterations in the intestinal flora and intestinal pathology. A T2DM mouse model was constructed by feeding mice a high-fat diet. Serum fat metabolism-related indices and insulin levels were biochemically detected. Serum inflammatory factors (IL-1β, IL-6, TNF-α, IL-10) and endotoxin (LPS) were measured by ELISA. Histopathological changes in the small intestines of mice were observed by HE. The short-chain fatty acid (SCFA) content was analyzed using GC-MS. Analysis of altered intestinal flora in T2DM mice was performed using a 16sRNA sequencing assay. Differences in lncRNA expression profiles in small intestinal tissues were analyzed using RNA-seq assays. Spearman's correlation analysis was used to correlate the expression of candidate lncRNAs with changes in differential gut flora. Spearman's correlation analysis was used to analyze the correlation between the expression of candidate differentially expressed lncRNAs, small intestinal permeability, and glucose absorption. We found that serum levels of LPS, BUN, Scr, TC, TG, LDL-C, IL-1β, IL-6, and TNF-α were elevated and levels of HDL-C, insulin, and IL-10 were decreased in T2DM mice. The ileal enterochromes of T2DM mice were disorganized and broken, the number of enterochromes was reduced, the local epithelial cells were necrotic, and the plasma membrane layer was locally absent. In addition, the protein expression of ZO-1 and occludin was decreased, and the protein expression of SGLT-1 and GLUT-2 was elevated in the model group compared to the control group.The levels of Acetic acid, Propionic acid and Butyric acid were decreased and the levels of Isobutyric acid andIsovaleric acid were increased, the abundance of beneficial bacteria was decreased and the abundance of harmfulbacteria was increased in the feces of T2DM mice. RNA-seq identified nine differentially expressed lncRNAs (LINC00675, Gm33838, Gm11655, LOC6613926, LOC6613788, LOC6613791, LOC6613795, Arhgap27os3, and A330023F24Rik). In addition, we found significant correlations between differentially expressed lncRNAs and a variety of intestinal flora, as well as between small intestinal permeability and glucose absorption. A significant correlation was observed between differentially expressed lncRNAs in the intestinal tissues of T2DM mice and intestinal flora imbalance, small intestinal permeability, and glucose absorption.

A23 IMPAIRMENT OF INTESTINAL CRYPTAL STEM CELL CYCLE AND PANETH CELL PROLIFERATION BY CHRONIC STRESS

Abstract Background The small intestine’s epithelial barrier is essential for intestinal homeostasis and host defense. It consists of epithelial cells that are constantly renewed by crypt stem cells and their progeny, which have different functions in the gut. Chronic stress can impair the barrier by modulating the gut-brain axis, which involves the hypothalamic-pituitary-adrenal (HPA) axis, the vagus nerve, and the immune system. Chronic stress can also alter the gut microbiota, which can further influence the barrier and immune system. Aims The present study examines how chronic stress affects the crypt stem cell niche and function in the small intestine. Methods Restraint stress was applied to 6-8 weeks old mice in a plastic container for 1 hour daily for 7 days. The dark/light transition box test was used to evaluate the stress-induced behavior change. The Ussing chamber technique was used to assess the paracellular permeability of the small intestine. RNA was extracted from the mucosa and submucosa layers of the small intestine, after removing the muscle layer, and RNA sequencing analysis was performed. Immunofluorescence analysis was also performed on the small intestinal tissues to detect the expression of various markers. To assess the in vivo effect of cortisol, dexamethasone (a synthetic steroid activating same receptors as cortisol), or metyrapone (an 11β-hydroxylation blocker to inhibit cortisol production), was applied to the mice. Results We found that restraint stress induced anxiety-like behavior, increased small intestinal epithelial permeability, and reduced villus and crypt length in mice. RNA sequencing analysis revealed that restraint stress upregulated steroid-driven pathways and downregulated cell cycle and cell mitosis pathways in the small intestinal mucosa, suggesting increased cortisol production and decreased stem cell activity. Immunofluorescence analysis confirmed that restraint stress reduced the expression of stem cell marker Olfm-4 and proliferation markers Ki-67 and p-H3 in the small intestinal crypts. Dexamethasone, a synthetic glucocorticoid, mimicked the effects of restraint stress on crypt stem cell proliferation, while metyrapone, a steroid synthesis inhibitor, attenuated the effects of restraint stress on crypt stem cell proliferation. Restraint stress and dexamethasone also reduced Paneth cell RNA expression and marker in the small intestine. Conclusions Chronic stress induces anxiety, barrier dysfunction, and epithelial shortening. Chronic stress also alters crypt stem cell and Paneth cell expression. These findings show how chronic stress impacts intestinal epithelial renewal and differentiation, which may affect intestinal health and disease. Funding Agencies JSPS

Increased Intestinal Permeability and Decreased Resiliency of the Intestinal Barrier in Alcoholic Liver Disease.

Only 20%-30% of individuals with alcohol use disorder (AUD) develop alcoholic liver disease (ALD). While the development of gut-derived endotoxemia is understood to be a required cofactor, increased intestinal permeability in ALD is not completely understood. We recruited 178 subjects-58 healthy controls (HCs), 32 with ALD, 53 with AUD but no liver disease (ALC), and 35 with metabolic dysfunction-associated steatotic liver disease (MASLD). Intestinal permeability was assessed by a sugar cocktail as a percentage of oral dose. The permeability test was repeated after an aspirin challenge in a subset. Five-hour urinary lactulose/mannitol ratio (primarily representing small intestinal permeability) was not statistically different in HC, ALC, ALD, and MASLD groups ( P = 0.40). Twenty-four-hour urinary sucralose (representing whole gut permeability) was increased in ALD ( F = 5.3, P < 0.01) and distinguished ALD from ALC; 24-hour sucralose/lactulose ratio (primarily representing colon permeability) separated the ALD group ( F = 10.2, P < 0.01) from the MASLD group. After aspirin challenge, intestinal permeability increased in all groups and ALD had the largest increase. In a group of patients, we confirmed that (i) the ALD group has increased intestinal permeability compared with the HC, ALC, or MASLD group. In addition, because small bowel permeability (lactulose/mannitol ratio) is normal, the disruption of intestinal barrier seems to be primarily in the large intestine; (ii) decreased resiliency of intestinal barrier to injurious agents (such as NSAID) might be the mechanism for gut leak in subset of AUD who develop ALD.

A green tea extract confection decreases circulating endotoxin and fasting glucose by improving gut barrier function but without affecting systemic inflammation: A double-blind, placebo-controlled randomized trial in healthy adults and adults with metabolic syndrome

Anti-inflammatory activities of catechin-rich green tea extract (GTE) in obese rodents protect against metabolic endotoxemia by decreasing intestinal permeability and absorption of gut-derived endotoxin. However, translation to human health has not been established. We hypothesized that GTE would reduce endotoxemia by decreasing gut permeability and intestinal and systemic inflammation in persons with metabolic syndrome (MetS) compared with healthy persons. A randomized, double-blind, placebo-controlled, crossover trial in healthy adults (n = 19, 34 ± 2 years) and adults with MetS (n = 21, 40 ± 3 years) examined 4-week administration of a decaffeinated GTE confection (890 mg/d total catechins) on serum endotoxin, intestinal permeability, gut and systemic inflammation, and cardiometabolic parameters. Compared with the placebo, the GTE confection decreased serum endotoxin (P = .023) in both healthy persons and those with MetS, while increasing concentrations of circulating catechins (P < .0001) and γ-valerolactones (P = .0001). Fecal calprotectin (P = .029) and myeloperoxidase (P = .048) concentrations were decreased by GTE regardless of health status. Following the ingestion of gut permeability probes, urinary lactose/mannitol (P = .043) but not sucralose/erythritol (P > .05) was decreased by GTE regardless of health status. No between-treatment differences (P > .05) were observed for plasma aminotransferases, blood pressure, plasma lipids, or body mass nor were plasma tumor necrosis factor-α, interleukin-6, or the ratio of lipopolysaccharide-binding protein/soluble cluster of differentiation-14 affected. However, fasting glucose in both study groups was decreased (P = .029) by the GTE confection compared with within-treatment arm baseline concentrations. These findings demonstrate that catechin-rich GTE is effective to decrease circulating endotoxin and improve glycemic control in healthy adults and those with MetS, likely by reducing gut inflammation and small intestinal permeability but without affecting systemic inflammation.

The effects of a 6-week intervention with Limosilactobacillus reuteri ATCC PTA 6475 alone and in combination with L. reuteri DSM 17938 on gut barrier function, immune markers, and symptoms in patients with IBS-D-An exploratory RCT.

An increased intestinal permeability is a common feature in patients with diarrhoea-predominant irritable bowel syndrome (IBS-D). Probiotics have shown to improve IBS symptoms and might also affect intestinal barrier function. The aim of this study was to investigate the effects of a 6-week intervention with Limosilactobacillus reuteri ATCC PTA 6475 alone (single strain) or in combination with Limosilactobacillus reuteri DSM 17938 (dual strain) on gut barrier function, immune markers, and symptoms in IBS-D patients (ClinicalTrials.gov registration number: NCT03986476). 65 IBS-D patients were randomised into three groups (placebo, single strain, dual strain). Small and large intestinal permeability were assessed using a multi-sugar urinary recovery test. Blood, saliva, faecal samples, and several symptom scales were collected before, and after three and six weeks of intervention. Small and large intestinal permeability as well as other markers of gut barrier function were not significantly affected by the probiotic interventions. Serum IL-6 levels showed a tendency to be reduced in the single strain group (descriptive p = 0.052). In addition, high-sensitivity C-reactive protein was significantly reduced in the dual strain group (p = 0.041). The participants in both treatment groups reported less gastrointestinal symptoms after three weeks, but this reached significance only in the dual strain group (total score: p = 0.032, pain subscore: p = 0.028). After six weeks, none of the assessed symptoms were significantly different from the placebo. The probiotic compounds investigated in this study did not seem to affect IBS-D patients' gut barrier function, but showed potential anti-inflammatory and symptom-improving properties, which need to be confirmed in larger study cohorts.

An extension of biorelevant fed-state dissolution tests to clinical pharmacokinetics – A study on gastrointestinal factors influencing rivaroxaban exposure and efficacy in atrial fibrillation patients

A direct oral anticoagulant rivaroxaban fails to prevent stroke and systemic embolism in one-to-several percent of patients with nonvalvular atrial fibrillation (NVAF), but the reasons are unknown. The study used semi-mechanistic in vitro-in vivo prediction (IVIVP) modeling to explore the reasons for ineffective thrombosis prevention in NVAF patients. Steady-state drug concentrations in plasma were measured at 0 h (Ctrough), 3 h (C3h), and 12 h post-dosing in thirty-four patients treated with 20 mg rivaroxaban daily. The clinical data were compared against “virtual twins” generated with a novel IVIVP model that combined drug dissolution modeling, mechanistic description of gastric drug transit, and population pharmacokinetics defining the variability of drug disposition. The nonresponders had significantly lower C3h and Ctrough than the responders (p < 0.001) and the covariates included in the population pharmacokinetic submodel did not fully explain this difference. Simulations involving varied gastrointestinal parameters in the “virtual twins” revealed that lower small intestinal effective permeability (Peff), rather than a slower stomach emptying rate, could explain low rivaroxaban exposure in the nonresponders. IVIVP modeling was effectively used for exploring pharmacotherapy failure. Low Peff, found as a major determinant of ineffective rivaroxaban treatment, encourages further research to find (pato)physiological factors influencing suboptimal absorption.

Effects of nutritional therapy on gastrointestinal microbial digestion and barrier defense markers in elderly patients with diabetes.

We sought to investigate the effects of gastrointestinal nutrition therapy on gastrointestinal microbial digestion and barrier defense markers in elderly patients with diabetes. A total of 120 elderly patients with type 2 diabetes were enrolled at our hospital between January 2020 and December 2022. The participants in this study were randomly allocated into either the nutritional group (n = 60) who underwent gastrointestinal nutrition therapy or the control group (n = 60) who underwent conventional T2DM diet management for a period of 12weeks. Clinical data, as well as small intestinal permeability measured by the lactulose-mannitol urine test, plasma circulating IL-6 and zonulin levels measured by ELISA, and expressions of ZO-1 and Claudin-3 in blood analyzed through Western blotting were collected. The nutrition group demonstrated a higher proportion of patients achieving HbA1c < 7% compared to the control group (P < 0.05). Moreover, the nutrition group exhibited a greater reduction in fasting and postprandial blood glucose levels compared to the control group (P < 0.05). The concentrations of formate-tetrahydrofolate ligase and acetic CoA transferase were significantly increased in the nutrition group compared to the control group (P < 0.05). Fecal analysis revealed higher levels of acetic acid and butyric acid in the nutrition group compared to the control group (P < 0.05). The ratio of lactulose to mannitol was higher in the nutrition group compared to the control group (P < 0.05). Furthermore, the nutrition group showed lower levels of IL-6 and zonulin compared to the control group (P < 0.05). Personalized gastrointestinal nutrition therapy was found to enhance the production of short-chain fatty acids and preserve intestinal permeability, leading to improved gastrointestinal microbial digestion and barrier defense in elderly patients with diabetes.

Prebiotics and Probiotics: Therapeutic Tools for Nonalcoholic Fatty Liver Disease.

Alterations in the gut-liver axis and changes in the gut microbiome are among the risk factors for the pathogenesis of non-alcoholic fatty liver disease (NAFLD). These patients show increased bacterial overgrowth in the small intestine and impaired intestinal permeability. Therefore, therapeutic options such as probiotics or prebiotics have been investigated to modulate intestinal microbiota composition to improve NAFLD. Most in vivo and in vitro probiotic studies have focused on reducing hepatic fat accumulation. The beneficial effects of probiotics on NAFLD have been demonstrated in animal models, and the most widely used microorganisms are those of the Lactobacillus and Bifidobacterium genera. In animal models, probiotics help restore the intestinal microbiota and improve the integrity of the intestinal barrier. This narrative review summarizes published evidence and the likely benefits of probiotics and prebiotics as a therapeutic option for patients with NAFLD.

Small Intestinal Permeability and Metabolomic Profiles in Feces and Plasma Associate With Clinical Response in Patients With Active Psoriatic Arthritis Participating in a Fecal Microbiota Transplantation Trial: Exploratory Findings From the FLORA Trial.

We investigated intestinal permeability and fecal, plasma, and urine metabolomic profiles in methotrexate-treated active psoriatic arthritis (PsA) and how this related to clinical response following one sham or fecal microbiota transplantation (FMT). This exploratory study is based on the FLORA trial cohort, in which 31 patients with moderate-to-high peripheral PsA disease activity, despite at least 3 months of methotrexate-treatment, were included in a 26-week, double-blind, 1:1 randomized, sham-controlled trial. Participants were randomly allocated to receive either one healthy donor FMT (n=15) or sham (n=16) via gastroscopy. The primary trial end point was the proportion of treatment failures through 26 weeks. We performed a lactulose-to-mannitol ratio (LMR) test at baseline (n=31) and at week 26 (n=26) to assess small intestinal permeability. Metabolomic profiles in fecal, plasma, and urine samples collected at baseline, weeks 4, 12, and 26 were measured using 1 H Nuclear Magnetic Resonance. Trial failures (n=7) had significantly higher LMR compared with responders (n=19) at week 26 (0.027 [0.017-0.33]) vs. 0.012 [0-0.064], P = 0.013), indicating increased intestinal permeability. Multivariate analysis revealed a significant model for responders (n=19) versus failures (n=12) at all time points based on their fecal (P < 0.0001) and plasma (P = 0.005) metabolomic profiles, whereas urine metabolomic profiles did not differ between groups (P = 1). Fecal N-acetyl glycoprotein GlycA correlated with Health Assessment Questionnaire Disability Index (coefficient=0.50; P = 0.03) and fecal propionate correlated with American College of Rheumatology 20 response at week 26 (coefficient=27, P = 0.02). Intestinal permeability and fecal and plasma metabolomic profiles of patients with PsA were associated with the primary clinical trial end point, failure versus responder.

The Potential Relationship between Gastric and Small Intestinal-Derived Endotoxin on Serum Testosterone in Men

The association between H. pylori and small intestinal permeability (IP) on serum testosterone levels in men as mediated by metabolic endotoxemia remains unclear. We sought to explore relationships using correlational analysis between H. pylori IgG class antibody levels and small IP via dual sugar probe analysis on T levels in 50 male participants of reproductive age. Sleep quality, physical activity levels, and Irritable Bowel Syndrome (IBS) symptom severity were measured as potential confounders. Measures for H. pylori (antibodies) increased small IP (lactulose/rhamnose ratio), and hypogonadism (testosterone) did not exceed diagnostic cut-off values for respective pathologies. There was no correlation between lactulose/rhamnose e ratio and GI function markers, zonulin, H. pylori, and IBS questionnaire scores; inflammatory markers, high-sensitivity C-reactive Protein (hsCRP) and Lipopolysaccharide-Binding Protein (LBP); nor endocrine markers, testosterone, Luteinizing hormone (LH), and Follicle-stimulating hormone (FSH). There was a moderate inverse relationship revealed between IBS symptom severity and LBP (r = −0.457, p = 0.004); and hsCRP and testosterone (r = −0.398, p = 0.004). This was independent of physical activity level and sleep quality, but not BMI, which supports the existing link between adiposity, inflammation, and hypogonadism currently present in the literature.

Plasma measurements of the dual sugar test reveal carbohydrate immediately alleviates intestinal permeability caused by exertional heat stress.

The aim of this set of randomised cross-over studies was to determine the impact of progressive heat exposure and carbohydrate or protein feeding during exertional stress on small intestine permeability using a dual sugar test. In our previous work, and typically in the field, recovery of lactulose and l-rhamnose is measured cumulatively in urine. This follow-up study exploits our novel high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) protocol to accurately quantify the sugars in plasma. Endurance-trained participants completed experimental trial A (ET-A; n=8), consisting of 2h running at 60% in temperate, warm and hot ambient conditions, and/or experimental trial B (ET-B; n=9), consisting of 2h running at 60% in the heat while consuming water, carbohydrate or protein. Blood samples were collected and plasma lactulose (L) and l-rhamnose (R) appearance, after dual sugar solution ingestion at 90min of exercise, was quantified by HPAEC-PAD to measure plasma L/R and reveal new information about intestinal permeability immediately post-exercise and during recovery. In ET-A, plasma L/R increased immediately post-exercise in hot compared with temperate and warm conditions, while, in ET-B, carbohydrate alleviated this, and this information was otherwise missed when measuring urine L/R. Consuming carbohydrate or protein before and during exercise attenuated small intestine permeability throughout recovery from exertional heat stress. We recommend using the dual sugar test with quantification of plasma sugars by HPAEC-PAD at intervals to maximise intestinal permeability data collection in exercise gastroenterology research, as this gives additional information compared to urinary measurements. KEY POINTS: Intestinal permeability is typically assessed using a dual sugar test, by administering a drink containing non-metabolisable sugars (e.g. lactulose (L) and l-rhamnose (R)) that can enter the circulation by paracellular translocation when the epithelium is compromised, and are subsequently measured in urine. We demonstrate that our recently developed ion chromatography protocol can be used to accurately quantify the L/R ratio in plasma, and that measuring L/R in plasma collected at intervals during the post-exercise recovery period reveals novel acute response information compared to measuring 5-h cumulative urine L/R. We confirm that exercising in hot ambient conditions increases intestinal epithelial permeability immediately after exercise, while consuming carbohydrate or protein immediately before and during exercise attenuates this. We recommend using our dual sugar absorption test protocol to maximise intestinal epithelial permeability data collection in exercise gastroenterology research and beyond.

The Effects of a Very-Low-Calorie Ketogenic Diet on the Intestinal Barrier Integrity and Function in Patients with Obesity: A Pilot Study.

The very-low-calorie ketogenic diet (VLCKD) is effective and safe for obese individuals, but limited information exists on its impact on the intestinal barrier. This study analyzed the effects of 8 weeks of VLCKD on 24 obese patients (11M/13F). Carbohydrate intake was fixed at 20-50 g/day, while protein and lipid intake varied from 1-1.4 g/kg of ideal body weight and 15-30 g per day, respectively. Daily calorie intake was below 800 kcal. The lactulose-mannitol absorption test assessed small intestinal permeability. Multiple markers, such as serum and fecal zonulin, fatty acid-binding protein, diamine oxidase concentrations, urinary dysbiosis markers (indican and skatole), and circulating lipopolysaccharide levels, were analyzed. Inflammation markers (serum interleukin 6, 8, 10, and tumor necrosis factor-α concentrations) were also evaluated. The results showed significant reductions in weight, BMI, and waist circumference post-diet. However, the lactulose-mannitol ratio increased by 76.5%, and a significant increase in dysbiosis markers at the end of the diet occurred. This trend was particularly evident in a subgroup of patients. Despite initial benefits, the VLCKD might negatively affect the intestinal barrier function in obese patients, potentially worsening their compromised intestinal balance.