Isolation of tryptophan as an inhibitor of ovalbumin permeation and analysis of its suppressive effect on oral sensitization

Fermentation Supernatant of Elderly Feces with Inulin and Partially Hydrolyzed Guar Gum Maintains the Barrier of Inflammation-Induced Caco-2/HT29-MTX-E12 Co-Cultured Cells

Intestinal barrier function declines with aging. We evaluated the effect of dietary fibers and indigestible oligosaccharides on intestinal barrier function by altering the microbiota of the elderly. The feces were anaerobically cultured with indigestible dextrin, inulin, partially hydrolyzed guar gum (PHGG), lactulose, raffinose, or alginate, and the fermented supernatant was added to inflammation-induced Caco-2/HT29-MTX-E12 co-cultured cells. Our data showed that inulin- and PHGG-derived supernatants exerted a protective effect on the intestinal barrier. The protective effect was significantly positively correlated with total short-chain fatty acids (SCFAs) and butyric acid production in the supernatant and negatively correlated with the claudin-2 (CLDN2) gene expression in the cultured cells. Furthermore, we showed that the CLDN2 levels are regulated by butyric acid. Thus, inulin and PHGG can change the intestinal environment of the elderly and maintain the intestinal barrier by accelerating the production of SCFAs and modifying the expression levels of barrier function-related genes.

Effects of an elemental diet to reduce adverse events in patients with esophageal cancer receiving docetaxel/cisplatin/5-fluorouracil: a phase III randomized controlled trial-EPOC 2 (JFMC49-1601-C5)

Background

Oral mucositis (OM) is an unpleasant adverse event in patients receiving chemotherapy. A prospective feasibility study showed that elemental diet (ED), an oral supplement that does not require digestion, may prevent OM. Based on this, we established a central review system for oral cavity assessment by dental oncology specialists blinded to background data. We used this system to elucidate the preventive effect of an ED against OM in patients with esophageal cancer receiving docetaxel, cisplatin, and 5-fluorouracil (DCF) therapy.

Patients and methods

In this phase III, multicenter, parallel-group, controlled trial, patients consuming a normal diet orally were randomly assigned (1 : 1) to receive two cycles of DCF with (group A) or without (group B) an ED (Elental® 160 g/day). We assessed the incidence of grade ≥2 OM evaluated by two reviewers, changes in body weight, prealbumin, C-reactive protein, and DCF completion rate based on ED compliance.

Results

Of the 117 patients randomly assigned to treatment, four failed to start treatment and were excluded from the primary analysis; thus, groups A and B comprised 55 and 58 patients, respectively. There were no significant differences in background characteristics. Grade ≥2 OM was observed in eight (15%) and 20 (34%) patients in groups A and B, respectively (P = 0.0141). Changes in body weight and prealbumin during the two DCF cycles were significantly higher in group A than B (P = 0.0022 and 0.0203, respectively). During the first cycle, changes in C-reactive protein were significantly lower in group A than B (P = 0.0338). In group A (receiving ED), the DCF completion rate was 100% in patients with 100% ED compliance and 70% in patients failing ED completion (P = 0.0046).

Conclusions

The study findings demonstrate that an ED can prevent OM in patients with esophageal cancer receiving chemotherapy.

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Patients receiving docetaxel, cisplatin, and 5-fluorouracil (DCF) chemotherapy commonly develop oral mucositis (OM).

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An elemental diet (ED) was able to prevent OM in patients with esophageal cancer receiving DCF.

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Grade ≥2 OM was observed in 15% of patients receiving the ED versus 34% of those not receiving the ED (P = 0.0141).

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Body weight was maintained in the ED group, and hematologic toxicities were lower, compared with the non-ED group.

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The DCF completion rate significantly correlated with ED compliance (P = 0.0046).

Gut Microbiome, Intestinal Permeability, and Tissue Bacteria in Metabolic Disease: Perpetrators or Bystanders?

The emerging evidence on the interconnectedness between the gut microbiome and host metabolism has led to a paradigm shift in the study of metabolic diseases such as obesity and type 2 diabetes with implications on both underlying pathophysiology and potential treatment. Mounting preclinical and clinical evidence of gut microbiota shifts, increased intestinal permeability in metabolic disease, and the critical positioning of the intestinal barrier at the interface between environment and internal milieu have led to the rekindling of the "leaky gut" concept. Although increased circulation of surrogate markers and directly measurable intestinal permeability have been linked to increased systemic inflammation in metabolic disease, mechanistic models behind this phenomenon are underdeveloped. Given repeated observations of microorganisms in several tissues with congruent phylogenetic findings, we review current evidence on these unanticipated niches, focusing specifically on the interaction between gut permeability and intestinal as well as extra-intestinal bacteria and their joint contributions to systemic inflammation and metabolism. We further address limitations of current studies and suggest strategies drawing on standard techniques for permeability measurement, recent advancements in microbial culture independent techniques and computational methodologies to robustly develop these concepts, which may be of considerable value for the development of prevention and treatment strategies.

Dietary α-Lactalbumin protects against thioacetamide-induced liver cirrhosis by maintaining gut-liver axis function in rats

We tested the hypothesis that α-lactalbumin inhibits the disruption of intestinal barrier function and liver cirrhosis by restoring gut-liver axis function in thioacetamide (TAA) -treated rats. Rat diets were supplemented with α-lactalbumin replacing 50% of dietary protein. After consuming α-lactalbumin for one week, rats were intraperitoneally injected with TAA twice a week for 14 weeks. The α-lactalbumin-enriched diet significantly inhibited the elevation of plasma alanine aminotransferase, aspartate aminotransferase, and hyaluronic acids. The supplement significantly reduced plasma lipopolysaccharide levels and increased occludin mRNA level. Hepatic fibrosis and regenerative nodules was developed and intestinal villi were shortened by TAA; α-Lactalbumin attenuated these histopathological changes. These results indicated that α-lactalbumin improved intestinal barrier function, suppressing endotoxin levels. These data also suggested that α-lactalbumin ameliorated the impairment of the gut-liver axis by TAA, inhibiting the development of liver cirrhosis.

Gut Permeability Might be Improved by Dietary Fiber in Individuals with Nonalcoholic Fatty Liver Disease (NAFLD) Undergoing Weight Reduction

(1) Introduction: Zonulin (ZO) has been proposed as a marker of intestinal permeability. Only a few studies have analyzed to date how diet influences the serum concentration of ZO among patients with non-alcoholic fatty liver disease (NAFLD). We performed a six-month dietetic intervention to evaluate the association between fiber intake and ZO concentration in 32 individuals with NAFLD. (2) Methods: Fiber content in the diet was estimated by Food Frequency Questionnaire (FFQ) and by analyzing 72-h nutritional diaries. ZO concentrations in serum were measured before and after the intervention by immunoenzymatic assay (ELISA). Fatty liver was quantified using the Hamaguchi score before and after the dietetic intervention. (3) Results: During the intervention, the dietary fiber intake increased from 19 g/day to the 29 g/day concomitant with an increase in the frequency of fiber consumption. All patients experienced significant (all p < 0.05) improvements in serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGTP) activities. We also detected decreased serum triglycerides (p = 0.036), homeostatic model assessment insulin resistance (HOMA-IR (p = 0.041) and insulin content (p = 0.34), and improvement of fatty liver status according to the Hamaguchi score (p = 0.009). ZO concentration in serum decreased by nearly 90% (7.335 ± 13.492 vs. 0.507 ± 0.762 ng/mL, p = 0.001) and correlated with the amount of dietary fiber intake (p = 0.043) as well as the degree of fatty liver (p = 0.037). (4) Conclusion: Increasing nutritional fiber results in reduced serum ZO levels, reduced liver enzymes and improved hepatic steatosis in patients with NAFLD, possibly by altering intestinal permeability. Increased dietary fiber intake should be recommended in patients with NAFLD.

Nutritional Keys for Intestinal Barrier Modulation

The intestinal tract represents the largest interface between the external environment and the human body. Nutrient uptake mostly happens in the intestinal tract, where the epithelial surface is constantly exposed to dietary antigens. Since inflammatory response toward these antigens may be deleterious for the host, a plethora of protective mechanisms take place to avoid or attenuate local damage. For instance, the intestinal barrier is able to elicit a dynamic response that either promotes or impairs luminal antigens adhesion and crossing. Regulation of intestinal barrier is crucial to control intestinal permeability whose increase is associated with chronic inflammatory conditions. The cross talk among bacteria, immune, and dietary factors is able to modulate the mucosal barrier function, as well as the intestinal permeability. Several nutritional products have recently been proposed as regulators of the epithelial barrier, even if their effects are in part contradictory. At the same time, the metabolic function of the microbiota generates new products with different effects based on the dietary content. Besides conventional treatments, novel therapies based on complementary nutrients are now growing. Fecal therapy has been recently used for the clinical treatment of refractory Clostridium difficile infection instead of the classical antibiotic therapy. In the present review, we will outline the epithelial response to nutritional components derived from dietary intake and microbial fermentation focusing on the consequent effects on the integrity of the epithelial barrier.

Regulation of intestinal epithelial permeability by tight junctions

The gastrointestinal epithelium forms the boundary between the body and external environment. It effectively provides a selective permeable barrier that limits the permeation of luminal noxious molecules, such as pathogens, toxins, and antigens, while allowing the appropriate absorption of nutrients and water. This selective permeable barrier is achieved by intercellular tight junction (TJ) structures, which regulate paracellular permeability. Disruption of the intestinal TJ barrier, followed by permeation of luminal noxious molecules, induces a perturbation of the mucosal immune system and inflammation, and can act as a trigger for the development of intestinal and systemic diseases. In this context, much effort has been taken to understand the roles of extracellular factors, including cytokines, pathogens, and food factors, for the regulation of the intestinal TJ barrier. Here, I discuss the regulation of the intestinal TJ barrier together with its implications for the pathogenesis of diseases.

Dietary carotenoids inhibit oral sensitization and the development of food allergy

Type-I allergic disorders and particularly food hypersensitivities are becoming increasingly common worldwide. This study investigated whether dietary enrichment with carotenoids inhibited oral sensitization to an antigen and the development of food allergies. The effects of a diet high in carotenoids were investigated in B10A mice that were orally sensitized to ovalbumin (OVA). The serum titers of OVA-specific immunoglobulin E (IgE), IgG1, and IgG2a were inhibited in mice fed ad libitum on a diet high in alpha- or beta-carotene compared to the control mice when orally sensitized to OVA. High alpha- and beta-carotene diets inhibited the immediate reduction in body temperature and rise in serum histamine associated with active systemic anaphylaxis in OVA-sensitized B10A mice. After re-stimulation with OVA in vitro, the production of T-helper 2-type cytokines by splenocytes from mice fed a diet high in carotenoids was lower than in control mice. Furthermore, the proportion of CD4(+) CD103(+) T cells in Peyer's patches of mice fed a carotenoid-rich diet was significantly lower than in control mice. These results suggest that an increased oral intake of carotenoids inhibits OVA-specific IgE and IgG1 production and antigen-induced anaphylactic responses by inhibiting specific T-cell activation in the mucosal immune system. A diet high in carotenoids might therefore prevent the development of food allergies.

Reduction of allergic airway eosinophilia by dietary raffinose in Brown Norway rats

Oral administration of raffinose, a naturally occurring indigestible oligosaccharide, has reportedly ameliorated atopic dermatitis in human subjects although the mechanism is unknown. The present study investigated the effect of dietary raffinose on allergen-induced airway eosinophilia in ovalbumin-sensitised Brown Norway rats as an atopic disease model. Brown Norway rats were immunised by subcutaneous injection with ovalbumin on day 0 and fed either a control diet or the diet supplemented with raffinose (50 g/kg diet). The rats were exposed to aerosolised ovalbumin on day 20, and broncho-alveolar lavage fluid was obtained on the next day. The number of eosinophils in the fluid was significantly lower in the rats fed the raffinose diet than in those fed the control diet. Dietary raffinose significantly reduced IL-4 and IL-5 mRNA levels in lung tissue and tended to lower ovalbumin-specific Ig E levels. Suppression of eosinophilia by dietary raffinose was still observed in caecectomised and neomycin-administered rats, suggesting little contribution by the colonic bacteria to the effect of raffinose. Intraperitoneal administration of raffinose also suppressed eosinophilia. Significant concentrations of raffinose were detected in portal venous and abdominal arterial plasma after the intragastric administration of raffinose. Overall, the findings suggest that dietary raffinose ameliorates allergic airway eosinophilia at least partly via post-absorptive mechanisms in Brown Norway rats.