Intestinal permeability, leaky gut, and intestinal disorders

Molecular Mechanisms of Lacticaseibacillus rhamnosus, LGG® Probiotic Function

To advance probiotic research, a comprehensive understanding of bacterial interactions with human physiology at the molecular and cellular levels is fundamental. Lacticaseibacillus rhamnosus LGG® is a bacterial strain that has long been recognized for its beneficial effects on human health. Probiotic effector molecules derived from LGG®, including secreted proteins, surface-anchored proteins, polysaccharides, and lipoteichoic acids, which interact with host physiological processes have been identified. In vitro and animal studies have revealed that specific LGG® effector molecules stimulate epithelial cell survival, preserve intestinal barrier integrity, reduce oxidative stress, mitigate excessive mucosal inflammation, enhance IgA secretion, and provide long-term protection through epigenetic imprinting. Pili on the cell surface of LGG® promote adhesion to the intestinal mucosa and ensure close contact to host cells. Extracellular vesicles produced by LGG® recapitulate many of these effects through their cargo of effector molecules. Collectively, the effector molecules of LGG® exert a significant influence on both the gut mucosa and immune system, which promotes intestinal homeostasis and immune tolerance.

Evaluation of mucosal immune profile associated with Zileuton nanocrystal-formulated BCS-II drug upon oral administration in Sprague Dawley rats

Nanocrystal drug formulation involves several critical manufacturing procedures that result in complex structures to improve drug solubility, dissolution, bioavailability, and consequently the efficacy of poorly soluble Biopharmaceutics Classification System (BCS) II and IV drugs. Nanocrystal formulation of an already approved oral drug may need additional immunotoxic assessment due to changes in the physical properties of the active pharmaceutical ingredient (API). In this study, we selected Zileuton, an FDA-approved drug that belongs to BCS-II for nanocrystal formulation. To evaluate the efficacy and mucosal immune profile of the nanocrystal drug, 10-week-old rats were dosed using capsules containing either API alone or nanocrystal formulated Zileuton (NDZ), or with a physical mixture (PM) using flexible oral gavage syringes. Control groups consisted of untreated, or placebo treated animals. Test formulations were administrated to rats at a dose of 30 mg/kg body weight (bw) once a day for 15 days. The rats treated with NDZ or PM had approximately 4.0 times lower (7.5 mg/kg bw) API when compared to the micron sized API treated rats. At the end of treatment, mucosal (intestinal tissue) and circulating cytokines were measured. The immunological response revealed that NDZ decreased several proinflammatory cytokines in the ileal mucosa (Interleukin-18, Tumor necrosis Factor-α and RANTES [regulated upon activation, normal T cell expressed and secreted]). A similar pattern in the cytokine profile was also observed for the micron sized API and PM treated rats. The cytokine production revealed that there was a significant increase in the production of IL-1β and IL-10 in the females in all experimental groups. Additionally, NDZ showed an immunosuppressive effect on proinflammatory cytokines both locally and systemically, which was similar to the response in micron sized API treated rats. These findings indicate that NDZ significantly decreased several proinflammatory cytokines and it displays less immunotoxicity, probably due to the nanocrystal formulation. Thus, the nanocrystal formulation is more suitable for oral drug delivery, as it exhibited better efficacy, safety, and reduced toxicity.

Microfluidic organotypic device to test intestinal mucosal barrier permeability ex vivo

To protect the body from external pathogens, the intestines have sophisticated epithelial and mucosal barriers. Disruptions to barrier integrity are associated with a variety of disorders such as irritable bowel disease, Crohn's disease, and celiac disease. One critical component of all barriers are collagens in the extracellular matrix. While the importance of the intestinal barrier is established, current models lack the ability to represent the complex biology that occurs at these barriers. For the current study a microfluidic device model was modified to determine the effectiveness of collagen breakdown to cause barrier disruption. Bacterial collagenase was added for 48 h to the luminal channel of a dual flow microfluidic device to examine changes in intestinal barrier integrity. Tissues exhibited dose-dependent alterations in immunoreactive collagen-1 and claudin-1, and coincident disruption of the epithelial monolayer barrier as indicated by goblet cell morphologies. This ex vivo model system offers promise for further studies exploring factors that affect gut barrier integrity and potential downstream consequences that cannot be studied in current models.

Biomarkers in IBD: What to Utilize for the Diagnosis?

The role of biomarkers in the diagnosis of inflammatory bowel disease is not fully characterized. C-reactive protein has a short half-life and elevates quickly after the onset of an inflammatory process; the performance is better in Crohn's disease than in ulcerative colitis. Erythrocyte sedimentation rate is easy to determine, widely available, and cheap, but the long half-life, the influence of age, anemia, smoking, and drugs limit its usefulness. Fecal markers have good specificity, but suboptimal accuracy. Microbial antibodies and novel immunological markers show promise but need further evidence before entering clinical practice. Proteomic methods could represent the dawn of a new era of stool protein/peptide biomarker panels able to select patients at risk of inflammatory bowel disease.

Relationship between Oat Consumption, Gut Microbiota Modulation, and Short-Chain Fatty Acid Synthesis: An Integrative Review

The gut microbiota consists of a set of microorganisms that colonizes the intestine and ferment fibers, among other nutrients, from the host's diet. A healthy gut microbiota, colonized mainly by beneficial microorganisms, has a positive effect on digestion and plays a role in disease prevention. However, dysregulation of the gut microbiota can contribute to various diseases. The nutrition of the host plays an important role in determining the composition of the gut microbiota. A healthy diet, rich in fiber, can beneficially modulate the gut microbiota. In this sense, oats are a source of both soluble and insoluble fiber. Oats are considered a functional ingredient with prebiotic potential and contain plant proteins, unsaturated fats, and antioxidant compounds. The impact of oat consumption on the gut microbiota is still emerging. Associations between oat consumption and the abundance of Akkermansia muciniphila, Roseburia, Lactobacillus, Bifidobacterium, and Faecalibacterium prausnitzii have already been observed. Therefore, this integrative review summarizes the findings from studies on the relationship between oat consumption, the gut microbiota, and the metabolites, mainly short-chain fatty acids, it produces.

Measuring intestinal permeability in celiac disease ex vivo, using Ussing chambers

Multicellular organisms need epithelial barriers to remain compartmentalized and protected from external influences. Although much progress has been made in understanding barrier integrity disruption in Celiac disease (CD), the regulatory and genetic mechanisms underlying the increased intestinal epithelial flux are still unknown. As we learn more about the regulation of permeability in homeostasis and pathogenesis, we will be able to develop strategies to strengthen the epithelial barrier function in intestinal disorders, including CD. For this purpose, Ussing chambers are increasingly used in native tissue, such as gut mucosa or cell monolayers, to assess the integrity of the barrier. In particular, the Ussing chambers allow the measurement of paracellular and transcellular parameters of CD small intestinal biopsies under physiologically specific conditions. In diverse types of diseases, this method is commonly used to determine epithelial barrier defects, but its application to CD has not yet been widely expanded. To provide a great model of barrier ex vivo studies in CD, we facilitate a standard protocol to measure paracellular and transcellular permeability using the Ussing chamber.

Polysaccharides from Bletilla striata protect against mercury-induced gastrointestinal toxicology in adult Drosophila melanogaster via modulation of sestrin

Oxidative stress was one of the major causes of heavy metal-induced toxicity in organisms. The polysaccharide from Bletilla striata (Orchidaceae) (BSP) has been recently recognized as a novel player in the management of oxidative stress response in organisms. Here, we took the midgut of adult Drosophila melanogaster (Diptera: Drosophilidae) (D. melanogaster), a functional equivalent to the mammalian intestine and stomach, as a model to evaluate the protective effects of BSP (50 μg/mL) on mercuric chloride-induced gastrointestinal toxicology in insects. As a result, BSP exposure significantly improved the survival rates and climbing ability of adult flies exposed to mercury. Further study demonstrated that BSP significantly alleviated the mercury-induced oxidative injury to midgut epithelium, at least partly, through increasing antioxidant enzyme activity (glutathione-S-transferase and superoxide dismutase), decreasing reactive oxidative species production, inhibiting cell death, restoring intestinal epithelial barrier and regulating intestinal stem cell-mediated tissue regeneration. Additionally, sestrin, an oxidative-stress gene, was required in mediating the protection of BSP against mercury-induced oxidative damage to midgut. This study suggested that BSP has great potential for future application in the treatment and prevention of heavy metal-induced gastrointestinal adversities in mammals.

Prediction of intestinal stem cell regulatory genes from Drosophila gut damage model created using multiple inducers: Differential gene expression-based protein-protein interaction network analysis

Intestinal tissue functions in innate immunity to prevent the entry of harmful substances, and to maintain homeostasis through the constant proliferation of intestinal stem cells (ISC). To understand the mechanisms which regulate ISC in response to gut damage, we identified 81 differentially expressed genes (DEGs) through RNA-seq analysis after oral administration of three intestinal-damaging substances to Drosophila melanogaster. Through protein-protein interaction (PPI) and functional annotation studies, the top 22 DEGs ordered by the number of nodes in the PPI network were analyzed in relation to cell development. Through network topology analysis, we identified 12 essential seed genes. From this we confirmed that p53, RpL17, Fmr1, Stat92E, CG31343, Cnot4, CG9281, CG8184, Evi5, and to were essential for ISC proliferation during gut damage using knockdown RNAi Drosophila. This study presents a method for identifying candidate genes relating to intestinal damage that has scope for furthering our understanding of gut disease.

Adherens junction proteins on the move—From the membrane to the nucleus in intestinal diseases

The function and structure of the mammalian epithelial cell layer is maintained by distinct intercellular adhesion complexes including adherens junctions (AJs), tight junctions, and desmosomes. The AJ is most integral for stabilizing cell-cell adhesion and conserving the structural integrity of epithelial tissues. AJs are comprised of the transmembrane protein E-cadherin and cytoplasmic catenin cofactors (α, β, γ, and p120-catenin). One organ where malfunction of AJ is a major contributor to disease states is the mammalian intestine. In the intestine, cell-cell adhesion complexes work synergistically to maintain structural integrity and homeostasis of the epithelium and prevent its malfunction. Consequently, when AJ integrity is compromised in the intestinal epithelium, the ensuing homeostatic disruption leads to diseases such as inflammatory bowel disease and colorectal carcinoma. In addition to their function at the plasma membrane, protein components of AJs also have nuclear functions and are thus implicated in regulating gene expression and intracellular signaling. Within the nucleus, AJ proteins have been shown to interact with transcription factors such as TCF/LEF and Kaiso (ZBTB33), which converge on the canonical Wnt signaling pathway. The multifaceted nature of AJ proteins highlights their complexity in modulating homeostasis and emphasizes the importance of their subcellular localization and expression in the mammalian intestine. In this review, we summarize the nuclear roles of AJ proteins in intestinal tissues; their interactions with transcription factors and how this leads to crosstalk with canonical Wnt signaling; and how nuclear AJ proteins are implicated in intestinal homeostasis and disease.

Purified fish skin collagen hydrolysate attenuates TNF-α induced barrier dysfunction in-vitro and DSS induced colitis in-vivo model

Inflammatory mediators are key components in establishing pathogenesis in inflammatory bowel disease. Balanced expression of anti-inflammatory and pro-inflammatory cytokines is an important cue in maintaining gut native and adaptive immunity. In the present study, purified hydrolysate fraction of fish skin collagen from Clarias batrachus and Pangasius pangasius was evaluated as a treatment agent against TNF-α induced barrier dysfunction in Caco-2 cell line model and DSS induced colitis in mice model. Cell adhesion on purified hydrolysate fraction coated surfaces was found to be enhanced with increasing concentration in both Clarias batrachus and Pangasius pangasius. Alkaline phosphatase activity was enhanced in a concentration-dependent manner. The paracellular permeability assay demonstrated that Pangasius pangasius purified hydrolysate fraction had countered TNF-α induced barrier dysfunction. Analysis of the tight junction proteins (occludin, zonulae occluden, and claudin) by RT PCR, immunofluorescence, and western blot, further confirmed the effectiveness of Pangasius pangasius purified hydrolysate fraction against TNF-α. The Pangasius pangasius purified hydrolysate fraction was further evaluated for efficacy in DSS-induced colitis mice model. Two concentration of Pangasius pangasius purified hydrolysate was chosen based on in-vitro experiments, 80 μg/kg and 200 μg/kg BW of Balb/C male mice administered through intra-rectal route along with fish skin collagen 80 μg/kg BW. Pangasius pangasius purified hydrolysate fraction treatment improved the clinical signs of colitis such as body weight, rectal bleeding, colon length, and stool consistency caused by DSS administration. Immunofluorescence of colon tissue section showed that Pangasius pangasius purified hydrolysate fraction enhanced the expression of occludin protein. This study hints at the use of Pangasius pangasius purified hydrolysate fraction as a potential nutraceutical or treatment agent in healing ulcers of the mucosa.

Elucidating the Role of Innate and Adaptive Immune Responses in the Pathogenesis of Canine Chronic Inflammatory Enteropathy-A Search for Potential Biomarkers

Simple Summary

Canine chronic inflammatory enteropathy (CIE) is a chronic disease affecting the small or large intestine and, in some cases, the stomach of dogs. This gastrointestinal disorder is common and is characterized by recurrent vomiting, diarrhea, and weight loss in affected dogs. The pathogenesis of IBD is not completely understood. Similar to human IBD, potential disease factors include genetics, environmental exposures, and dysregulation of the microbiota and the immune response. Some important components of the innate and adaptive immune response involved in CIE pathogenesis have been described. However, the immunopathogenesis of the disease has not been fully elucidated. In this review, we summarized the literature associated with the different cell types and molecules involved in the immunopathogenesis of CIE, with the aim of advancing the search for biomarkers with possible diagnostic, prognostic, or therapeutic utility.

Abstract

Canine chronic inflammatory enteropathy (CIE) is one of the most common chronic gastrointestinal diseases affecting dogs worldwide. Genetic and environmental factors, as well as intestinal microbiota and dysregulated host immune responses, participate in this multifactorial disease. Despite advances explaining the immunological and molecular mechanisms involved in CIE development, the exact pathogenesis is still unknown. This review compiles the latest reports and advances that describe the main molecular and cellular mechanisms of both the innate and adaptive immune responses involved in canine CIE pathogenesis. Future studies should focus research on the characterization of the immunopathogenesis of canine CIE in order to advance the establishment of biomarkers and molecular targets of diagnostic, prognostic, or therapeutic utility.

Microbiome-based interventions to modulate gut ecology and the immune system

The gut microbiome lies at the intersection between the environment and the host, with the ability to modify host responses to disease-relevant exposures and stimuli. This is evident in how enteric microbes interact with the immune system, e.g., supporting immune maturation in early life, affecting drug efficacy via modulation of immune responses, or influencing development of immune cell populations and their mediators. Many factors modulate gut ecosystem dynamics during daily life and we are just beginning to realise the therapeutic and prophylactic potential of microbiome-based interventions. These approaches vary in application, goal, and mechanisms of action. Some modify the entire community, such as nutritional approaches or faecal microbiota transplantation, while others, such as phage therapy, probiotics, and prebiotics, target specific taxa or strains. In this review, we assessed the experimental evidence for microbiome-based interventions, with a particular focus on their clinical relevance, ecological effects, and modulation of the immune system.

Tight junctions: from molecules to gastrointestinal diseases

Intestinal epithelium functions as a tissue barrier to prevent interaction between the internal compartment and the external milieu. Intestinal barrier function also determines epithelial polarity for the absorption of nutrients and the secretion of waste products. These vital functions require strong integrity of tight junction proteins. In fact, intestinal tight junctions that seal the paracellular space can restrict mucosal-to-serosal transport of hostile luminal contents. Tight junctions can form both an absolute barrier and a paracellular ion channel. Although defective tight junctions potentially lead to compromised intestinal barrier and the development and progression of gastrointestinal (GI) diseases, no FDA-approved therapies that recover the epithelial tight junction barrier are currently available in clinical practice. Here, we discuss the impacts and regulatory mechanisms of tight junction disruption in the gut and related diseases. We also provide an overview of potential therapeutic targets to restore the epithelial tight junction barrier in the GI tract.

A Simple, Robust, and Convenient HPLC Assay for Urinary Lactulose and Mannitol in the Dual Sugar Absorption Test

Background: Heterogeneous laborious analytical methodologies for the determination of urinary lactulose and mannitol limit their utility in intestinal permeability testing. Methods: We developed an assay using a Shimadzu HPLC system, an Aminex HPX87C column, and refractive index detection. The test was calibrated using a series of dilutions from standard stock solutions of lactulose and mannitol ‘spiked’ into urine samples. The utility to quantify urinary excretion during the dual sugar absorption test over 6 h was also determined. Results: Lactulose and mannitol were eluted isocratically at 5.7 and 10.1 min, respectively, with water as a mobile phase at a flow rate of 0.3 mL min⁻¹, 858 psi, 60 °C. The calibration curves for both sugars were linear up to 500 µg mL⁻¹ with a limit of detection in standard solutions at 4 µg mL⁻¹ and in ‘spiked’ urine samples at 15 µg mL⁻¹. The intra-assay and inter-assay CVs were between 2.0–5.1% and 2.0–5.1% for lactulose and 2.5–4.4% and 2.8–3.9% for mannitol. The urinary profiles of the 6 h absorption of lactulose and mannitol showed similar peak-retention times to standard solutions and were well-resolved at 5.9 and 10.4 min, respectively. Conclusions: The assay was easy to automate, using commonly available equipment and convenient requiring no prior laborious sample derivatization. The simplicity, reproducibility, and robustness of this assay facilitates its use in routine clinical settings for the quantification of intestinal permeability.

β-defensin 118 attenuates inflammation and injury of intestinal epithelial cells upon enterotoxigenic Escherichia coli challenge

Background

Antimicrobial peptides including various defensins have been attracting considerable research interest worldwide, as they have potential to substitute for antibiotics. Moreover, AMPs also have immunomodulatory activity. In this study, we explored the role and its potential mechanisms of β-defensin 118 (DEFB118) in alleviating inflammation and injury of IPEC-J2 cells (porcine jejunum epithelial cell line) upon the enterotoxigenic Escherichia coli (ETEC) challenge.

Results

The porcine jejunum epithelial cell line (IPEC-J2) pretreated with or without DEFB118 (25 μg/mL) were challenged by ETEC (1×10⁶ CFU) or culture medium. We showed that DEFB118 pretreatment significantly increased the cell viability (P<0.05) and decreased the expressions of inflammatory cytokines such as the interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in IPEC-J2 cells exposure to ETEC (P<0.05). Interestingly, DEFB118 pretreatment significantly elevated the abundance of the major tight-junction protein zonula occludens-1 (ZO-1), but decreased the number of apoptotic cells upon ETEC challenge (P<0.05). The expression of caspase 3, caspase 8, and caspase 9 were downregulated by DEFB118 in the IPEC-J2 cells exposure to ETEC (P<0.05). Importantly, DEFB118 suppressed two critical inflammation-associated signaling proteins, nuclear factor-kappa-B inhibitor alpha (IκB-α) and nuclear factor-kappaB (NF-κB) in the ETEC-challenged IPEC-J2 cells.

Conclusions

DEFB118 can alleviate ETEC-induced inflammation in IPEC-J2 cells through inhibition of the NF-κB signaling pathway, resulting in reduced secretion of inflammatory cytokines and decreased cell apoptosis. Therefore, DEFB118 can act as a novel anti-inflammatory agent.

Plasma Metabolic and Lipidomic Fingerprinting of Individuals with Increased Intestinal Permeability

The dual-sugar intestinal permeability test is a commonly used test to assess changes in gut barrier function. However, it does not identify functional changes and the exact mechanism of damage caused by the increased intestinal permeability. This study aims to explore the application of untargeted metabolomics and lipidomics to identify markers of increased intestinal permeability. Fifty fasting male participants (18–50 years) attended a single visit to conduct the following procedures: assessment of anthropometric measures, assessment of gastrointestinal symptoms, intestinal permeability test, and assessment of blood samples 90 min post-administration of the intestinal permeability test. Rhamnose and lactulose were analysed using gas chromatography-mass spectrometry (GC-MS). Untargeted polar metabolites and lipidomics were assessed by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF MS). There was an elevated lactulose/rhamnose ratio in 27 subjects, indicating increased permeability compared to the remaining 23 control subjects. There were no significant differences between groups in characteristics such as age, body mass index (BMI), weight, height, and waist conference. Fourteen metabolites from the targeted metabolomics data were identified as statistically significant in the plasma samples from intestinal permeability subjects. The untargeted metabolomics and lipidomics analyses yielded fifteen and fifty-one statistically significant features, respectively. Individuals with slightly elevated intestinal permeability had altered energy, nucleotide, and amino acid metabolism, in addition to increased glutamine levels. Whether these biomarkers may be used to predict the early onset of leaky gut warrants further investigation.

Leaky Gum: The Revisited Origin of Systemic Diseases

The oral cavity is the gateway for microorganisms into your body where they disseminate not only to the directly connected respiratory and digestive tracts but also to the many remote organs. Oral microbiota, travelling to the end of the intestine and circulating in our bodies through blood vessels, not only affect a gut microbiome profile but also lead to many systemic diseases. By gathering information accumulated from the era of focal infection theory to the age of revolution in microbiome research, we propose a pivotal role of “leaky gum”, as an analogy of “leaky gut”, to underscore the importance of the oral cavity in systemic health. The oral cavity has unique structures, the gingival sulcus (GS) and the junctional epithelium (JE) below the GS, which are rarely found anywhere else in our body. The JE is attached to the tooth enamel and cementum by hemidesmosome (HD), which is structurally weaker than desmosome and is, thus, vulnerable to microbial infiltration. In the GS, microbial biofilms can build up for life, unlike the biofilms on the skin and intestinal mucosa that fall off by the natural process. Thus, we emphasize that the GS and the JE are the weakest leaky point for microbes to invade the human body, making the leaky gum just as important as, or even more important than, the leaky gut.

The Microbiota-Gut-Brain Axis in Alzheimer's Disease: A Review of Taxonomic Alterations and Potential Avenues for Interventions

OBJECTIVE

The gut microbiome is a complex community of microorganisms that inhabit the gastrointestinal tract. The microbiota-gut-brain axis encompasses a bidirectional communication system that allows the gut to influence the brain via neural, endocrine, immune, and metabolic signaling. Differences in the gut microbiome have been associated with psychiatric and neurological disorders, including Alzheimer's Disease (ad). Understanding these ad-associated alterations may offer novel insight into the pathology and treatment of ad.

METHOD

We conducted a narrative review of clinical studies investigating the gut microbiome in ad, organizing the results by phyla to understand the biological contributions of the gut microbial community to ad pathology and clinical features. We also reviewed randomized clinical trials of interventions targeting the microbiome to ameliorate ad symptoms and biomarkers.

RESULTS

Alpha diversity is reduced in patients with ad. Within Firmicutes, taxa that produce beneficial metabolites are reduced in ad, including Clostridiaceae, Lachnospiraceae, Ruminococcus, and Eubacterium. Within Bacteroidetes, findings were mixed, with studies showing either reduced or increased abundance of Bacteroides in mild cognitive impairment or ad patients. Proteobacteria that produce toxins tend to be increased in ad patients, including Escherichia/Shigella. A Mediterranean-ketogenic dietary intervention significantly increased beneficial short-chain fatty acids and taxa that were inversely correlated with changes in ad pathological markers. Probiotic supplementation with Lactobacillus spp. and Bifidobacterium spp. improved cognitive function and reduced inflammatory and metabolic markers in patients with ad.

CONCLUSIONS

The gut microbiome may provide insight into ad pathology and be a novel target for intervention. Potential therapeutics include probiotics and dietary intervention.

Allomyrina dichotoma larval extract has protective effects against gut permeability of dextran sulfate sodium-fed Drosophila by E-cadherin and armadillo

ETHNOPHARMACOLOGICAL RELEVANCE

Larvae of the rhinoceros beetle (Allomyrina dichotoma) (ADL) are used ethnopharmacologically to treat gut-related disorders in Korea and China since 1596 and are also approved as a safe novel food with high nutritional value.

AIM OF THE STUDY

We investigated the protective effects of ADL extract against leaky gut disease using a Drosophila model and sought to elucidate the underlying biological mechanisms.

MATERIALS AND METHODS

We examined the protective effects of ADL extract (2 mg/mL) against the leaky gut disease using a dextran sulfate sodium (DSS)-induced leaky gut Drosophila melanogaster model.

RESULTS

We found that oral administration of ADL extracts significantly increase the survival rate of DSS-fed Drosophila. Under conditions of DSS-induced gut damage, ADL extract reduced gut cell apoptosis and gut permeability, resulting in the maintenance of gut tissue homeostasis. Furthermore, we observed that oral administration of ADL extract can induce high levels of E-cadherin gene expression and also restored the original membrane localization of DSS-disrupted E-cadherin contiguous with the armadillo.

CONCLUSION

We concluded that ADL extract plays an important role in maintaining gut homeostasis through the up-regulation of E-cadherin and that it may have a protective effect against leaky gut syndrome.

Desmoglein2 Regulates Claudin2 Expression by Sequestering PI-3-Kinase in Intestinal Epithelial Cells

Inflammation-induced reduction of intestinal desmosomal cadherin Desmoglein 2 (Dsg2) is linked to changes of tight junctions (TJ) leading to impaired intestinal epithelial barrier (IEB) function by undefined mechanisms. We characterized the interplay between loss of Dsg2 and upregulation of pore-forming TJ protein Claudin2. Intraperitoneal application of Dsg2-stablising Tandem peptide (TP) attenuated impaired IEB function, reduction of Dsg2 and increased Claudin2 in DSS-induced colitis in C57Bl/6 mice. TP blocked loss of Dsg2-mediated adhesion and upregulation of Claudin2 in Caco2 cells challenged with TNFα. In Dsg2-deficient Caco2 cells basal expression of Claudin2 was increased which was paralleled by reduced transepithelial electrical resistance and by augmented phosphorylation of AKT^Ser473 under basal conditions. Inhibition of phosphoinositid-3-kinase proved that PI-3-kinase/AKT-signaling is critical to upregulate Claudin2. In immunostaining PI-3-kinase dissociated from Dsg2 under inflammatory conditions. Immunoprecipitations and proximity ligation assays confirmed a direct interaction of Dsg2 and PI-3-kinase which was abrogated following TNFα application. In summary, Dsg2 regulates Claudin2 expression by sequestering PI-3-kinase to the cell borders in intestinal epithelium.

Minimally Invasive Image-Guided Gut Transport Function Measurement Probe

INTRODUCTION

Diseases such as celiac disease, environmental enteric dysfunction, infectious gastroenteritis, type II diabetes and inflammatory bowel disease are associated with increased gut permeability. Dual sugar absorption tests, such as the lactulose to rhamnose ratio (L:R) test, are the current standard for measuring gut permeability. Although easy to administer in adults, the L:R test has a number of drawbacks. These include an inability to assess for spatial heterogeneity in gut permeability that may distinguish different disease severity or pathology, additional sample collection for immunoassays, and challenges in carrying out the test in certain populations such as infants and small children. Here, we demonstrate a minimally invasive probe for real-time localized gut permeability evaluation through gut potential difference (GPD) measurement.

MATERIALS AND METHODS

The probe has an outer diameter of 1.2 mm diameter and can be deployed in the gut of unsedated subjects via a transnasal introduction tube (TNIT) that is akin to an intestinal feeding tube. The GPD probe consists of an Ag/AgCl electrode, an optical probe and a perfusion channel all housed within a transparent sheath. Lactated Ringer's (LR) solution is pumped through the perfusion channel to provide ionic contact between the electrodes and the gut lining. The optical probe captures non-scanning (M-mode) OCT images to confirm electrode contact with the gut lining. A separate skin patch probe is placed over an abraded skin area to provide reference for the GPD measurements. Swine studies were conducted to validate the GPD probe. GPD in the duodenum was modulated by perfusing 45 ml of 45 mM glucose.

RESULTS

GPD values of -13.1 ± 2.8 mV were measured in the duodenum across four swine studies. The change in GPD in the duodenum with the addition of glucose was -10.5 ± 2.4 mV (p < 0.001). M-mode OCT images provided electrode-tissue contact information, which was vital in ascertaining the probe's proximity to the gut mucosa.

CONCLUSION

We developed and demonstrated a minimally invasive method for investigating gastrointestinal permeability consisting of an image guided GPD probe that can be used in unsedated subjects.

The Role of Processed Aloe vera Gel in Intestinal Tight Junction: An In Vivo and In Vitro Study

Leaky gut is a condition of increased paracellular permeability of the intestine due to compromised tight junction barriers. In recent years, this affliction has drawn the attention of scientists from different fields, as a myriad of studies prosecuted it to be the silent culprit of various immune diseases. Due to various controversies surrounding its culpability in the clinic, approaches to leaky gut are restricted in maintaining a healthy lifestyle, avoiding irritating factors, and practicing alternative medicine, including the consumption of supplements. In the current study, we investigate the tight junction-modulating effects of processed Aloe vera gel (PAG), comprising 5–400-kD polysaccharides as the main components. Our results show that oral treatment of 143 mg/kg PAG daily for 10 days improves the age-related leaky gut condition in old mice, by reducing their individual urinal lactulose/mannitol (L/M) ratio. In concordance with in vivo experiments, PAG treatment at dose 400 μg/mL accelerated the polarization process of Caco-2 monolayers. The underlying mechanism was attributed to enhancement in the expression of intestinal tight junction-associated scaffold protein zonula occludens (ZO)-1 at the translation level. This was induced by activation of the MAPK/ERK signaling pathway, which inhibits the translation repressor 4E-BP1. In conclusion, we propose that consuming PAG as a complementary food has the potential to benefit high-risk patients.

Interplay of Microbiota and Citrullination in the Immunopathogenesis of Rheumatoid Arthritis

Microbiota is a balanced ecosystem that has important functions to the host health including development, defense, digestion, and absorption of dietary fibers and minerals, vitamin synthesizes, protection, and training the host immune system. On the other hand, its dysbiosis is linked to many human diseases such as rheumatoid arthritis (RA). The RA is an inflammatory autoimmune disorder caused by genetic and environmental factors; microbiota may be considered as a risk environmental factor for it. Citrullination is a post-translation modification (PMT) that converts the amino acid arginine to amino acid citrulline in certain proteins. These citrullinated proteins are recognized as a foreign antigen by the immune system resulting in the upregulation of inflammatory action such as in RA. The current work highlights the effect of both gut and oral microbiota dysbiosis on the development of RA, as well as discusses how the alteration in microbiota composition leads to the overgrowth of some bacterial species that entangled in RA pathogenicity. The evidence suggested that some oral and gut microbial species such as Porphyromonas gingivalis and Prevotella copri, respectively, contribute to RA pathogenesis. During dysbiosis, these bacteria can mediate the citrullination of either human or bacteria proteins to trigger an immune response that leads to the generation of autoantibodies.

The role of nutrition in space exploration: Implications for sensorimotor, cognition, behavior and the cerebral changes due to the exposure to radiation, altered gravity, and isolation/confinement hazards of spaceflight

Multi-year crewed space exploration missions are now on the horizon; therefore, it is important that we understand and mitigate the physiological effects of spaceflight. The spaceflight hazards-radiation, isolation, confinement, and altered gravity-have the potential to contribute to neuroinflammation and produce long-term cognitive and behavioral effects-while the fifth hazard, distance from earth, limits capabilities to mitigate these risks. Accumulated evidence suggests that nutrition has an important role in optimizing cognition and reducing the risk of neurodegenerative diseases caused by neuroinflammation. Here we review the nutritional perspective of how these spaceflight hazards affect the astronaut's brain, behavior, performance, and sensorimotor function. We also assess potential nutrient/nutritional countermeasures that could prevent or mitigate spaceflight risks and ensure that crewmembers remain healthy and perform well during their missions. Just as history has taught us the importance of nutrition in terrestrial exploration, we must understand the role of nutrition in the development and mitigation of spaceflight risks before humans can successfully explore beyond low-Earth orbit.

Resveratrol Prevents Campylobacter jejuni-Induced Leaky gut by Restoring Occludin and Claudin-5 in the Paracellular Leak Pathway

Campylobacter jejuni is a bacterial human pathogen causing gastroenteritis and sequelae like irritable bowel syndrome. Epidemiologists count the human campylobacteriosis by C. jejuni as the most common foodborne zoonosis and bacterial diarrheal disease worldwide. Based on bioinformatics predictions for potential protective compounds in campylobacteriosis, the question was raised whether the plant-based polyphenol resveratrol is sufficient to attenuate intestinal epithelial damage induced by C. jejuni. We investigated this by performing experimental infection studies in an epithelial cell culture and the secondary abiotic IL-10-/- mouse model. In C. jejuni-infected human colonic HT-29/B6 cell monolayers, transepithelial electrical resistance (TER) was decreased and the paracellular marker flux of fluorescein (332 Da) increased. Concomitantly, the tight junction (TJ) proteins occludin and claudin-5 were re-distributed off the tight junction domain. This was accompanied by an increased induction of epithelial apoptosis, both changes contributing to compromised barrier function and the opening of the leak pathway induced by C. jejuni. In parallel, the recovery experiments with the application of resveratrol revealed a functional improvement of the disturbed epithelial barrier in both models in vitro and in vivo. During treatment with resveratrol, TJ localization of occludin and claudin-5 was fully restored in the paracellular domain of HT-29/B6 cells. Moreover, resveratrol decreased the rate of epithelial apoptosis. These resveratrol-induced molecular and cellular effects would therefore be expected to improve epithelial barrier function, thereby minimizing the so-called leaky gut phenomenon. In conclusion, the induction of the leak pathway by C. jejuni and the restoration of barrier function by resveratrol demonstrates its effectiveness as a potential preventive or therapeutic method of mitigating the leaky gut associated with campylobacteriosis.

Bu-Zhong-Yi-Qi Granule Enhances Colonic Tight Junction Integrity via TLR4/NF-κB/MLCK Signaling Pathway in Ulcerative Colitis Rats

Background

Bu-zhong-yi-qi granule (BZYQ), a sort of Chinese herbal medicine, has exhibited therapeutic effects on ulcerative colitis (UC). However, the mechanism of BZYQ has not been fully clarified. This study was aimed at investigating the effects of BZYQ on UC rats model and at exploring its potential mechanism.

Methods

The UC rats were established by enema of trinitrobenzene sulfonic acid (TNBS). The therapeutic effects of BZYQ treatment were evaluated by disease activity index (DAI), colon macroscopic damage index (CMDI) scores, and histological observation. The mRNA levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-10 (IL-10) were measured by quantitative real time-polymerase chain reaction (qPCR). The expression of tight junction (TJ) proteins, occludin and claudin-1, in the colon was determined by Western blot and immunofluorescence. The expression of toll-like receptors 4 (TLR4), nuclear factor-kappa B (NF-κB), p-NF-κB, myosin light chain kinase (MLCK), MLC, and p-MLC levels in colon was determined by Western blot or qPCR.

Results

The results showed that BZYQ could attenuate DAI, CMDI, and histological inflammation. TJ proteins expression was decreased in UC rats, but treatment with BZYQ restored the expression of occludin and claudin-1. In addition, BZYQ administration ameliorated UC-associated increase in the production of TNF-α, IL-1β, and the expression of TLR4, NF-κB, p-NF-κB, MLCK, MLC, and p-MLC, while BZYQ administration increased the production of IL-10.

Conclusions

The therapeutic effect of BZYQ on UC is at least partially through regulation of the secretion of some inflammatory cytokines and improvement of TJ integrity via TLR4/NF-κB/MLCK pathway.

Baitouweng Decoction Ameliorates Ulcerative Colitis in Mice Partially Attributed to Regulating Th17/Treg Balance and Restoring Intestinal Epithelial Barrier

Ulcerative colitis (UC) is a chronic intestinal disease with unclear pathogenesis. With an increasing global prevalence over the past two decades, UC poses a serious threat to public health. Baitouweng decoction (BTW), a traditional Chinese medicine, has been shown to have good clinical efficacy for treating intestinal inflammation. Yet, the efficacy of BTW in UC and the underlying mechanism remain unclear. The current study aimed to determine whether BTW suppressed intestinal inflammation in mice and the potential mechanism. We used a dextran sulfate sodium (DSS)-induced murine colitis model to test the anti-inflammatory efficacy of BTW. Clinical symptoms were scored by the disease activity index (DAI), and the colon length and pathological changes in colon tissue were also used to further evaluate the efficacy of BTW. Precisely how BTW affected immune function and the intestinal barrier of UC mice was also examined. BTW significantly reduced DAI score and colonic pathological damage. BTW regulated the balance between T helper (Th)17 and regulatory T (Treg) cells, decreased interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, and increased IL-10 levels. BTW reduced intestinal permeability of UC mice, increased expression of tight junction proteins (occludin and zonula occludens-1), and decreased expression of phospho-nuclear factor (p-NF)-κB and phospho-extracellular signal-regulated kinase (p-ERK) in the colon. BTW inhibited the ERK/p-NF-κB signaling pathway and suppressed expression of cyclo-oxygenase-2 and inducible NO synthase in lipopolysaccharide-activated RAW 264.7 cells. BTW significantly promoted the synthesis of short-chain fatty acids in the gut, particularly acetate, propionate, isobutyric acid, and isovalerate. The results suggest that BTW can protect against DSS-induced UC. The mechanism may be partially attributed to regulating the balance of Th17/Treg cells and restoring the intestinal epithelial barrier.

Enabling rational gut microbiome manipulations by understanding gut ecology through experimentally-evidenced in silico models

The gut microbiome has emerged as a contributing factor in non-communicable disease, rendering it a target of health-promoting interventions. Yet current understanding of the host-microbiome dynamic is insufficient to predict the variation in intervention outcomes across individuals. We explore the mechanisms that underpin the gut bacterial ecosystem and highlight how a more complete understanding of this ecology will enable improved intervention outcomes. This ecology varies within the gut over space and time. Interventions disrupt these processes, with cascading consequences throughout the ecosystem. In vivo studies cannot isolate and probe these processes at the required spatiotemporal resolutions, and in vitro studies lack the representative complexity required. However, we highlight that, together, both approaches can inform in silico models that integrate cellular-level dynamics, can extrapolate to explain bacterial community outcomes, permit experimentation and observation over ecological processes at high spatiotemporal resolution, and can serve as predictive platforms on which to prototype interventions. Thus, it is a concerted integration of these techniques that will enable rational targeted manipulations of the gut ecosystem.

Maltodextrin-induced intestinal injury in a neonatal mouse model

Prematurity and enteral feedings are major risk factors for intestinal injury leading to necrotizing enterocolitis (NEC). An immature digestive system can lead to maldigestion of macronutrients and increased vulnerability to intestinal injury. The aim of this study was to test in neonatal mice the effect of maltodextrin, a complex carbohydrate, on the risk of intestinal injury. The goal was to develop a robust and highly reproducible murine model of intestinal injury that allows insight into the pathogenesis and therapeutic interventions of nutrient-driven intestinal injury. Five- to 6-day-old C57BL/6 mice were assigned to the following groups: dam fed (D); D+hypoxia+Klebsiella pneumoniae; maltodextrin-dominant human infant formula (M) only; M+hypoxia; and M+hypoxia+K. pneumoniae. The mice in all M groups were gavage fed five times a day for 4 days. Mice were exposed to hypoxia twice a day for 10 min prior to the first and last feedings, and K. pneumoniae was added to feedings as per group assignment. Mice in all M groups demonstrated reduced body weight, increased small intestinal dilatation and increased intestinal injury scores. Maltodextrin-dominant infant formula with hypoxia led to intestinal injury in neonatal mice accompanied by loss of villi, increased MUC2 production, altered expression of tight junction proteins, enhanced intestinal permeability, increased cell death and higher levels of intestinal inflammatory mediators. This robust and highly reproducible model allows for further interrogation of the effects of nutrients on pathogenic factors leading to intestinal injury and NEC in preterm infants.This article has an associated First Person interview with the first author of the paper.

The association between aspirin use and depression: a systematic review and meta-analysis of observational studies

PURPOSE

Many clinical trials and observational studies have been conducted under the premise that the anti-inflammatory effect of aspirin may prevent depression. These studies, however, showed inconsistent results. To inspect the association between aspirin use and depression, we conducted a meta-analysis of observational studies.

METHODS

In August 2019, two authors independently searched PubMed, EMBASE, and PsycINFO to retrieve observational epidemiological studies presenting an association between aspirin use and depression. Case-control and cohort studies were included, and odds ratios (ORs) or relative risks (RRs) with 95% confidence intervals (CIs) for the risk of depression were estimated using a random-effects model. In addition, number needed to harm (NNH) was calculated to measure the rates of depression.

RESULTS

In total, 12 observational studies-five case-control studies and seven prospective cohort studies-were included in this meta-analysis. The random-effects model demonstrated a significant association between aspirin use and depression (OR/RR 1.10; 95% CI: 1.05-1.16) with insignificant heterogeneity (I² = 23.3%). The risk estimates of depression from prospective cohort studies were similar (RR 1.11; 95% CI: 1.08-1.14), and heterogeneity was not observed (I² = 0.0%). In the subgroup meta-analysis, a duration of aspirin use ≥5 years and a dosage ≥500 mg daily were also associated with depression. The NNH for depression with aspirin use >5 years was 103 (95% CI 91-111) indicating that observed event is rare.

CONCLUSIONS

Aspirin use was associated with depression in the present meta-analysis. One of the major limitations is the lack of detail and consistency with respect to exposure verification in the included papers. Another limitation is the lack of randomized controlled studies and prospective cohort studies.

The DNA Sensor AIM2 Protects against Streptozotocin-Induced Type 1 Diabetes by Regulating Intestinal Homeostasis via the IL-18 Pathway

Pattern recognition receptors (PRRs), such as Nod2, Nlrp3, Tlr2, Trl4, and Tlr9, are directly involved in type 1 diabetes (T1D) susceptibility. However, the role of the cytosolic DNA sensor, AIM2, in T1D pathogenesis is still unknown. Here, we demonstrate that C57BL/6 mice lacking AIM2 (AIM2^−/−) are prone to streptozotocin (STZ)-induced T1D, compared to WT C57BL/6 mice. The AIM2^−/− mice phenotype is associated with a greater proinflammatory response in pancreatic tissues, alterations in gut microbiota and bacterial translocation to pancreatic lymph nodes (PLNs). These alterations are related to an increased intestinal permeability mediated by tight-junction disruption. Notably, AIM2^−/− mice treated with broad-spectrum antibiotics (ABX) are protected from STZ-induced T1D and display a lower pancreatic proinflammatory response. Mechanistically, the AIM2 inflammasome is activated in vivo, leading to an IL-18 release in the ileum at 15 days after an STZ injection. IL-18 favors RegIIIγ production, thus mitigating gut microbiota alterations and reinforcing the intestinal barrier function. Together, our findings show a regulatory role of AIM2, mediated by IL-18, in shaping gut microbiota and reducing bacterial translocation and proinflammatory response against insulin-producing β cells, which ultimately results in protection against T1D onset in an STZ-induced diabetes model.

Impact of chemotherapy on the association between fear of cancer recurrence and the gut microbiota in breast cancer survivors

BACKGROUND

Dysfunctional processing of fear memory may be involved in the pathophysiology of fear of cancer recurrence (FCR), which is cited as the major unmet psychological need of cancer survivors. Emerging evidence has shown that the microbiota-gut-brain (MGB) axis affects depressive and anxiety disorders, and chemotherapy-associated psychological distress. We therefore hypothesized that the gut microbiota is associated with FCR in cancer survivors.

METHODS

This cross-sectional study enrolled women diagnosed with invasive breast cancer who were not currently undergoing chemotherapy. Fecal samples were obtained to assess the gut microbiota. FCR grade was assessed using the Concerns About Recurrence Scale (CARS).

RESULTS

Mean age of the participants (n = 126) was 58 years; 47% had stage I disease. Multiple regression analysis with adjustment for possible confounders showed that the relative abundance of the Bacteroides genus (beta = 0.180, p = 0.03) was significantly and directly associated with FCR. In the 57 participants with a history of chemotherapy, higher FCR was associated with lower microbial diversity (p = 0.04), lower relative abundance of Firmicutes (p = 0.03) and higher relative abundance of Bacteroidetes (p = 0.04) at the phylum level, and higher relative abundance of Bacteroides (p < 0.01) and lower relative abundance of Lachnospiraceae.g (p = 0.03) and Ruminococcus (p = 0.02) at the genus level.

CONCLUSION

Our findings provide the first evidence of an association between the gut microbiota and FCR and suggest that chemotherapy-induced changes in gut microbiota can influence FCR. Further studies should examine the effects of the gut microbiota on FCR using a prospective design.

The Functional Role of Fecal Microbiota Transplantation on Dextran Sulfate Sodium-Induced Colitis in Mice

Increasingly studies revealed that dysbiosis of gut microbiota plays a pivotal role in the pathogenesis of ulcerative colitis (UC). Fecal microbiota transplantation (FMT) has drawn more and more attention and become an important therapeutic approach. This study aims to examine the facts about the effective components and look into potential mechanisms of FMT. Colitis was induced by 3% (w/v) dextran sulfate sodium (DSS) in drinking water for 7 days. Colitis mice were administered by oral gavage with fecal suspension, fecal supernatant, fecal bacteria, or boiling-killed fecal bacteria from healthy controls and the disease activity index was monitored daily. On the seventh day, mice were euthanized. The length, histological score, parameters related to inflammation, gut barrier functions of the colon, activities of digestive protease and β-glucuronidase in feces were measured. All of the four fecal components showed certain degree of efficacy in DSS-induced colitis, while transplantation of fecal suspension showed the most potent effect as demonstrated by less body weight loss, lower disease activity scores, more expression of tight junction proteins and TRAF6 and IκBα, less expression of TNF-α, IL-1β, IL-10, TLR-4, and MyD88 in gut tissue, as well as restoration of fecal β-glucuronidase and decreases in fecal digestive proteases. These results provide a novel insight into the possible mechanism of FMT and may help to improve and optimize clinical use of FMT.

Relationship between Changes in Microbiota and Liver Steatosis Induced by High-Fat Feeding-A Review of Rodent Models

Several studies have observed that gut microbiota can play a critical role in nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) development. The gut microbiota is influenced by different environmental factors, which include diet. The aim of the present review is to summarize the information provided in the literature concerning the impact of changes in gut microbiota on the effects which dietary fat has on liver steatosis in rodent models. Most studies in which high-fat feeding has induced steatosis have reported reduced microbiota diversity, regardless of the percentage of energy provided by fat. At the phylum level, an increase in Firmicutes and a reduction in Bacteroidetes is commonly found, although widely diverging results have been described at class, order, family, and genus levels, likely due to differences in experimental design. Unfortunately, this fact makes it difficult to reach clear conclusions concerning the specific microbiota patterns associated with this feeding pattern. With regard to the relationship between high-fat feeding-induced changes in liver and microbiota composition, although several mechanisms such as alteration of gut integrity and increased permeability, inflammation, and metabolite production have been proposed, more scientific evidence is needed to address this issue and thus further studies are needed.

Occludin endocytosis is involved in the disruption of the intestinal epithelial barrier in a mouse model of alcoholic steatohepatitis

OBJECTIVE

We aimed to investigate the involvement of the endocytosis of occludin, a key component of tight junction (TJ), in the ethanol-induced disassembly of TJ in a model of alcoholic steatohepatitis.

METHODS

Wild-type mice were fed an ethanol-containing or isocaloric liquid diet for 8 weeks and then assessed for liver injury (histopathology and measurement of serum enzymes), gut permeability (in vivo lactulose/mannitol and ex vivo dye leakage assays), intestinal epithelium ultrastructure (transmission electron microscopy), and intestinal occludin localization (immunofluorescence microscopy). The human intestinal epithelial cell line Caco-2 was also analyzed in vitro for the effects of ethanol on the barrier function (transepithelial electrical resistance), occludin localization (immunofluorescence microscopy and Western blotting), and endocytosis pathways (double-labeling immunofluorescence microscopy with selective pathway inhibitors).

RESULTS

The ethanol-fed mice developed steatohepatitis and displayed intestinal barrier dysfunction, the disruption of intestinal TJ, and enhanced intestinal endocytosis of occluding compared with the control mice. In the Caco-2 monolayers, ethanol treatment decreased transepithelial electrical resistance, disrupted TJ formation, and enhanced occludin endocytosis in a dose- and time-dependent manner. These deleterious events were reversed by pretreating the Caco-2 cells with a selective pharmacological inhibitor of macropinocytosis, but not with the inhibitors of clathrin or caveolin-mediated endocytic pathways.

CONCLUSION

Chronic ethanol exposure may increase intestinal permeability by inducing the micropinocytosis of occludin, resulting in the disruption of intestinal TJ.

Unravelled facets of milk derived opioid peptides: a focus on gut physiology, fractures and obesity

Beyond being a source of key nutrients, bovine milk influences physiological functions by synthesising bioactive peptides during the process of digestion. Some of the claimed negative health outcomes associated with milk consumption, such as cardiovascular diseases and type 1 diabetes may be attributed to an opioid peptide, beta-casomorphin-7 (BCM-7), derived from A1 beta-casein. BCM-7 exerts its function by binding to the μ-opioid receptors in the body. It is hypothesised that activation of the μ-opioid receptors in the gut can alter gut microbial composition, impair gut barrier integrity and bile acid metabolism, in addition to increasing gastrointestinal transit time and gut inflammation. Further, it is hypothesised that BCM-7 may influence fractures and obesity via μ-opioid receptor pathways. In conclusion, it appears that BCM-7 might have multiple functions pertinent to human health; however, the evidence is limited and warrants further pre-clinical and clinical studies for hypothesis confirmation.

Intestinal Permeability Measured by Urinary Sucrose Excretion Correlates with Serum Zonulin and Faecal Calprotectin Concentrations in UC Patients in Remission

Background and Aims

Ulcerative colitis (UC) is associated with an increased intestinal permeability, possibly through a dysbiosis of intestinal bacteria. We investigated which markers are most relevant to assess intestinal permeability in UC patients and whether probiotics had an effect on these markers.

Methods

In this twelve-week placebo-controlled randomized double-blind study, twenty-five subjects with UC in remission received either placebo or a multispecies probiotics. Samples of blood, urine, and faeces were taken at baseline, week 6, and week 12 to assess intestinal permeability and inflammation. Diaries and Bristol stool scale were kept to record stool frequency and consistency. Quality of life was scored from 32–224 with the inflammatory bowel disease questionnaire (IBD-Q).

Results

This group of UC patients, in clinical remission, did not show increased intestinal permeability at baseline of this study. During the study, no significant group or time effects were found for intestinal permeability measured by the 5-sugar absorption test, serum zonulin, and faecal zonulin. Likewise, the inflammatory markers C-reactive protein (CRP), calprotectin, and the cytokines IFNγ, TNFα, IL-6, and IL-10 were not significantly affected. Stool frequency and consistency were not significantly affected either. The IBD-Q score, 194 for the probiotics group and 195 for the placebo group, remained unaffected. Correlations were tested between all outcomes; urinary sucrose excretion was significantly correlated with serum zonulin (r = 0.62) and faecal calprotectin (r = 0.55). Faecal zonulin was not significantly correlated with any of the other markers.

Conclusion

Serum zonulin may be a more relevant biomarker of intestinal permeability than faecal zonulin, due to its correlation with other biomarkers of intestinal permeability. UC patients in remission did not show an effect of the probiotic treatment or a change in gut permeability. This should not discourage further studies because effects might be present during active disease or shortly after a flare up.

Microbes and the Mind: How Bacteria Shape Affect, Neurological Processes, Cognition, Social Relationships, Development, and Pathology

Recent data suggest that the human body is not so exclusively human after all. Specifically, humans share their bodies with approximately 10 trillion microorganisms, collectively known as the microbiome. Chief among these microbes are bacteria, and there is a growing consensus that they are critical to virtually all facets of normative functioning. This article reviews the ways in which bacteria shape affect, neurological processes, cognition, social relationships, development, and psychological pathology. To date, the vast majority of research on interactions between microbes and humans has been conducted by scientists outside the field of psychology, despite the fact that psychological scientists are experts in many of the topics being explored. This review aims to orient psychological scientists to the most relevant research and perspectives regarding the microbiome so that we might contribute to the now widespread, interdisciplinary effort to understand the relationship between microbes and the mind.

MMP-9-induced increase in intestinal epithelial tight permeability is mediated by p38 kinase signaling pathway activation of MLCK gene

Matrix metalloproteinase-9 (MMP-9) has been implicated as being an important pathogenic factor in inflammatory bowel disease (IBD). MMP-9 is markedly elevated in intestinal tissue of patients with IBD, and IBD patients have a defective intestinal tight-junction (TJ) barrier manifested by an increase in intestinal permeability. The loss of intestinal epithelial barrier function is an important contributing factor in the development and prolongation of intestinal inflammation; however, the role of MMP-9 in intestinal barrier function remains unclear. The purpose of this study was to investigate the effect of MMP-9 on the intestinal epithelial TJ barrier and to delineate the intracellular mechanisms involved by using in vitro (filter-grown Caco-2 monolayers) and in vivo (mouse small intestine recycling perfusion) systems. MMP-9 caused a time- and dose-dependent increase in Caco-2 TJ permeability. MMP-9 also caused an increase in myosin light-chain kinase (MLCK) gene activity, protein expression, and enzymatic activity. The pharmacological MLCK inhibition and siRNA-induced knockdown of MLCK inhibited the MMP-9-induced increase in Caco-2 TJ permeability. MMP-9 caused a rapid activation of the p38 kinase signaling pathway and inhibition of p38 kinase activity prevented the MMP-9-induced increase in MLCK gene activity and the increase in Caco-2 TJ permeability. MMP-9 also caused an increase in mouse intestinal permeability in vivo, which was accompanied by an increase in MLCK expression. The MMP-9-induced increase in mouse intestinal permeability was inhibited in MLCK-deficient mice. These data show for the first time that the MMP-9-induced increase in intestinal TJ permeability in vitro and in vivo was mediated by the p38 kinase signal transduction pathway upregulation of MLCK gene activity and that therapeutic targeting of these pathways can prevent the MMP-9-induced increase in intestinal TJ permeability. NEW & NOTEWORTHY MMP-9 is highly elevated in patients with IBD. IBD patients have compromised intestinal TJ barrier function manifested by an increase in intestinal permeability and intestinal inflammation. This study shows that MMP-9, at clinically achievable concentrations, causes an increase in intestinal TJ permeability in vitro and in vivo. In addition, a MMP-9-induced increase in intestinal TJ permeability was mediated by an increase in MLCK gene and protein expression via the p38 kinase pathway.

Influence of the Maillard-type caseinate glycation with lactose on the intestinal barrier activity of the caseinate digest in IEC-6 cells

The glycated caseinate digest of the Maillard-type shows lower capability than the caseinate digest to enhance the intestinal barrier function of IEC-6 cells.

Can the gut be the missing piece in uncovering PD pathogenesis?

It is now well established that Parkinson's disease (PD) is not only a movement disorder of the CNS but also a gastrointestinal disorder affecting the enteric nervous system (ENS). The gut-brain axis is a bidirectional communication between the brain and the gastrointestinal tract, which comprises besides the CNS and the ENS, the intestinal epithelial barrier, the intestinal microbiota and the enteroendocrine systems. In this review, we present the clinical and pathological evidence suggesting that the gut-brain axis is dysfunctional in PD by discussing the possible role of gut microbiota, inflammation and permeability in the development of the disease.

Characterisation of a canine epithelial cell line for modelling the intestinal barrier

Little is known about how food interacts with the intestinal epithelium during the digestion process. However, it is known that ingredients in food can modulate the intestinal barrier, and have the potential to disrupt homeostasis of the gut. Here, we characterise a conditionally immortalised canine intestinal epithelial cell (cIEC) line for use in in vitro assays, to assess the effect of food ingredients on intestinal barrier function, permeability, cell health, and inflammation. Microscopy and flow cytometry confirmed that cIECs had a phenotype consistent with those of epithelial origin, and were able to differentiate to mature enterocytes. The cIECs also formed a monolayer when grown on Transwell® inserts, producing functional tight junctions between the cells. In contrast to the human-derived Caco-2 cell line, transepithelial electrical resistance (TEER) was increased in cIECs in response to two different raw ingredients. The exposure of cIECs to known inflammatory stimuli and raw ingredients induced the nuclear translocation of nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-?B). This work demonstrates the value of a unique cIEC in vitro model to study the effects of food ingredients on canine intestinal function and health, and supports continued efforts to reduce and refine the use of animals in scientific research.

AMP-activated protein kinase: a therapeutic target in intestinal diseases

Adenosine monophosphate (AMP)-activated protein kinase (AMPK), a highly conserved energy sensor, has a crucial role in cardiovascular, neurodegenerative and inflammatory diseases, as well as in cancer and metabolic disorders. Accumulating studies have demonstrated that AMPK activation enhances paracellular junctions, nutrient transporters, autophagy and apoptosis, and suppresses inflammation and carcinogenesis in the intestine, indicating an essential role of AMPK in intestinal health. AMPK inactivation is an aetiological factor in intestinal dysfunctions. This review summarizes the favourable outcomes of AMPK activation on intestinal health, and discusses AMPK as a potential therapeutic target for intestinal diseases.

Mechanisms underlying the effects of n-3 polyunsaturated fatty acids on fear memory processing and their hypothetical effects on fear of cancer recurrence in cancer survivors

The relationship of n-3 polyunsaturated fatty acids (PUFAs) and gut microbiota with brain function has been extensively reported. Here, we review how n-3 polyunsaturated fatty acids affect fear memory processing. n-3 PUFAs may improve dysfunctional fear memory processing via immunomodulation/anti-inflammation, increased BDNF, upregulated adult neurogenesis, modulated signal transduction, and microbiota-gut-brain axis normalization. We emphasize how n-3 PUFAs affect this axis and also focus on the hypothetical effects of PUFAs in fear of cancer recurrence (FCR), the primary psychological unmet need of cancer survivors. Its pathophysiology may be similar to that of post-traumatic stress disorder (PTSD), which involves dysfunctional fear memory processing. Due to fewer adverse effects than psychotropic drugs, nutritional interventions involving n-3 PUFAs should be acceptable for physically vulnerable cancer survivors. We are currently studying the relationship of FCR with n-3 PUFAs and gut microbiota in cancer survivors to provide them with a nutritional intervention that protects against FCR.

Infection Elicited Autoimmunity and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: An Explanatory Model

Myalgic encephalomyelitis (ME) often also called chronic fatigue syndrome (ME/CFS) is a common, debilitating, disease of unknown origin. Although a subject of controversy and a considerable scientific literature, we think that a solid understanding of ME/CFS pathogenesis is emerging. In this study, we compiled recent findings and placed them in the context of the clinical picture and natural history of the disease. A pattern emerged, giving rise to an explanatory model. ME/CFS often starts after or during an infection. A logical explanation is that the infection initiates an autoreactive process, which affects several functions, including brain and energy metabolism. According to our model for ME/CFS pathogenesis, patients with a genetic predisposition and dysbiosis experience a gradual development of B cell clones prone to autoreactivity. Under normal circumstances these B cell offsprings would have led to tolerance. Subsequent exogenous microbial exposition (triggering) can lead to comorbidities such as fibromyalgia, thyroid disorder, and orthostatic hypotension. A decisive infectious trigger may then lead to immunization against autoantigens involved in aerobic energy production and/or hormone receptors and ion channel proteins, producing postexertional malaise and ME/CFS, affecting both muscle and brain. In principle, cloning and sequencing of immunoglobulin variable domains could reveal the evolution of pathogenic clones. Although evidence consistent with the model accumulated in recent years, there are several missing links in it. Hopefully, the hypothesis generates testable propositions that can augment the understanding of the pathogenesis of ME/CFS.

Aspirin and incident depressive symptoms: A longitudinal cohort study over 8 years

OBJECTIVE

Aspirin exhibits anti-atherosclerotic and anti-inflammatory properties-two potential risk factors for depression. The relationship between aspirin use and depression, however, remains unclear. We investigated whether the aspirin use is associated with a decreased incidence of depressive symptoms in a large North American cohort.

METHODS

Data from the Osteoarthritis Initiative dataset, a multicenter, longitudinal study on community-dwelling adults was analyzed. Aspirin use was defined through self-report in the past 30 days and confirmed by a trained interviewer. Incident depressive symptoms were defined as a score of ≥16 in the 20-item Center for Epidemiologic Studies-Depression scale.

RESULTS

A total of 137 participants (mean age 65 y, 55.5% female) were using aspirin at baseline. Compared with 4003 participants not taking aspirin, no differences in Center for Epidemiologic Studies-Depression at baseline were evident (P = .65). After a median follow-up time of 8 years, the incidence of depressive symptoms was similar in those taking aspirin at baseline (43; 95% CI, 3-60) and in aspirin nonusers (38; 95% CI, 36-41) per 1000 y; log-rank test = 0.63). Based on Cox's regression analysis adjusted for 11 potential confounders, aspirin use was not significantly associated with the development of depressive symptoms (hazard ratio = 1.12; 95% CI, 0.78-1.62; P = .54). Adjustment for propensity scores or the use of propensity score matching did not alter the results.

CONCLUSION

Our study found that prescription of aspirin offered no significant protection against incident depressive symptoms. Whether aspirin is beneficial in a subgroup of depression with high levels of inflammation remains to be investigated in future studies.

Purple Potato Extract Promotes Intestinal Epithelial Differentiation and Barrier Function by Activating AMP-Activated Protein Kinase

SCOPE

Perturbation of gut epithelial barrier function induces inflammation and other health problems that originate from the gut. Purple potato contains a high content of beneficial polyphenolic compounds. The objective of this study is to evaluate the effect of purple potato extract (PPE) on intestinal differentiation and barrier function, and explore its underlying mechanism using Caco-2 cells and ex vivo cultured gut tissues.

METHODS AND RESULTS

PPE increases transepithelial electrical resistance and decreases FITC-dextran paracellular flux in Caco-2 cells, which are associated with strengthened intestinal epithelial differentiation in both Caco-2 cells and ex vivo guts. Furthermore, PPE treatment enhances AMP-activated protein kinase (AMPK) activity, concomitant with the increased expression of CDX2, a key transcriptional factor regulating intestinal epithelial differentiation. Knocking out AMPK using CRISPR/Cas9 system abolishes the positive effects of PPE on intestinal epithelial differentiation and barrier function, in junction with the reduced expression of CDX2.

CONCLUSION

PPE improves gut epithelial differentiation and barrier function via activating AMPK, indicating that PPE, as well as associated purple potato consumption, could be used as a supportive dietary therapeutic strategy for improving gut epithelial health.

Elevation of serum pyruvate kinase M2 (PKM2) in IBD and its relationship to IBD indices

OBJECTIVES

Endoscopy remains the gold standard to diagnose and evaluate inflammatory bowel disease (IBD) activity. Current biomarkers or their combinations cannot adequately predict IBD risk, diagnosis, progression or relapse, and response to therapy. Pyruvate kinase M2 (PKM2) is emerging as a significant mediator of the inflammatory process. We aimed to assess levels of serum PKM2 in healthy and newly diagnosed IBD patients and its relationship with IBD indices and microbiota changes.

DESIGN AND METHODS

IBD serum samples from newly diagnosed patients were collected and analyzed using a PKM2-ELISA and correlated with disease activity scores, IBD disease type, and intestinal microbiota. Furthermore, we tested the genetic and protein expression of PKM2 in an in vitro intestinal cell model of inflammation.

RESULTS

Serum PKM2 levels were 6-fold higher in IBD patients compared to healthy controls, with no sensitivity to disease phenotype (Crohn's Disease or Ulcerative Colitis) or localization of inflammation. Serum PKM2 had considerably less interindividual variability than established IBD fecal biomarkers. A positive Pearson correlation (r=0.6121) existed between serum PKM2 and Bacteroidetes fecal levels in Crohn's disease (CD), while a negative (r=-0.6128) correlation was observed with Actinobacteria fecal levels. Furthermore, LPS (500ng/mL) significantly increased PKM2 expression in vitro, which was significantly suppressed by an anti-inflammatory flaxseed bioactive agent.

CONCLUSION

Our data suggests PKM2 as a putative biomarker for IBD and the dysbiosis of microflora in CD. Investigations involving larger number of clinical patients are necessary to validate its use as a serum biomarker of IBD.