Remodeling of Tight Junctions and Enhancement of Barrier Integrity of the CACO-2 Intestinal Epithelial Cell Layer by Micronutrients

The influence of fruit juice extracts on glucose intestinal transporters and antioxidant genes in a Caco-2 and HT29-MTX co-culture cell system

In recent years, the interest of consumers in fruit juice extracts as nutraceuticals has increased. Fruits, especially red berries, contain valuable bioactive compounds such as polyphenols. Polyphenols are often associated with anti-oxidant, anti-inflammatory, anti-diabetic, anti-cancer, cardioprotective and gastroprotective properties. However, the relationship between the various effects of fruit juice extracts and their influence on the permeability of the intestinal barrier, as well as their influence on glucose transport across the intestinal membrane, is not known. Therefore, in the present study, anthocyanins and copigments were obtained from 11 fruit juice extracts by XAD7 column chromatography and characterized their health-promoting effects, as well as their influence on the intestinal membrane. Chokeberry, pomegranate and blueberry extracts showed the highest antioxidant activity, but showed incomplete regeneration of the intestinal membrane upon treatment-induced higher permeability. This may depended on the high anthocyanin level of these extracts. Treatments with gojiberry extract, elderberry extract and the copigment fraction of apple achieved the best suitable regeneration of the intestinal barrier. The transcription of epithelial glucose transporters GLUT1 und GLUT2 as well as for the oxidative stress genes catalase (CAT) and superoxide dismutase (SOD) were most effectively reduced by chokeberry extract. To sum up, fruit juice extracts possess high antioxidant potentials and can reduce the expression of antioxidant enzymes and glucose transporters in colon cells. While the glucose uptake may be reduced, the intestinal permeability is increased, which varies due to the extract composition. Therefore, fruit juice extracts need to be fractionated and characterized in more detail to identify the health-beneficial compounds.

Postbiotics: As a Promising Tools in the Treatment of Celiac Disease

Celiac disease (CD) can be considered an autoimmune problem, a disease caused by gluten sensitivity in the body. Gluten is found in foods such as barley, wheat, and rye. This ailment manifests in individuals with hereditary susceptibility and under the sway of environmental stimulants, counting, in addition to gluten and intestinal microbiota dysbiosis. Currently, the only recommended treatment for this condition is to follow a gluten-free diet for life. In this review, we scrutinized the studies of recent years that focused on the use of postbiotics in vitro and in vivo in CD. The investigation of postbiotics in CD could be intriguing to observe their diverse effects on several pathways. This study highlights the definitions, characteristics, and safety issues of postbiotics and their possible biological role in the prevention and treatment of CD, as well as their application in the food and drug industry.

A Synthetic Formula Amino Acid Diet Leads to Microbiome Dysbiosis, Reduced Colon Length, Inflammation, and Altered Locomotor Activity in C57BL/6J Mice

The effects of synthetic, free-amino acid diets, similar to those prescribed as supplements for (phenylketonuria) PKU patients, on gut microbiota and overall health are not well understood. In the current, multidisciplinary study, we examined the effects of a synthetically-derived, low-fiber, amino acid diet on behavior, cognition, gut microbiome composition, and inflammatory markers. A cohort of 20 male C57BL/6J mice were randomly assigned to either a standard or synthetic diet (n = 10) at post-natal day 21 and maintained for 13 weeks. Sequencing of the 16S rRNA gene from fecal samples revealed decreased bacterial diversity, increased abundance of bacteria associated with disease, such as Prevotella, and a downward shift in gut microbiota associated with fermentation pathways in the synthetic diet group. Furthermore, there were decreased levels of short chain fatty acids and shortening of the colon in mice consuming the synthetic diet. Finally, we measured TNF-α, IL-6, and IL-10 in serum, the hippocampus, and colon, and found that the synthetic diet significantly increased IL-6 production in the hippocampus. These results demonstrate the importance of a multidisciplinary approach to future diet and microbiome studies, as diet not only impacts the gut microbiome composition but potentially systemic health as well.

Gut microbiota-derived short chain fatty acids act as mediators of the gut-brain axis targeting age-related neurodegenerative disorders: a narrative review

Neurodegenerative diseases associated with aging are often accompanied by cognitive decline and gut microbiota disorder. But the impact of gut microbiota on these cognitive disturbances remains incompletely understood. Short chain fatty acids (SCFAs) are major metabolites produced by gut microbiota during the digestion of dietary fiber, serving as an energy source for gut epithelial cells and/or circulating to other organs, such as the liver and brain, through the bloodstream. SCFAs have been shown to cross the blood-brain barrier and played crucial roles in brain metabolism, with potential implications in mediating Alzheimer's disease (AD) and Parkinson's disease (PD). However, the underlying mechanisms that SCFAs might influence psychological functioning, including affective and cognitive processes and their neural basis, have not been fully elucidated. Furthermore, the dietary sources which determine these SCFAs production was not thoroughly evaluated yet. This comprehensive review explores the production of SCFAs by gut microbiota, their transportation through the gut-brain axis, and the potential mechanisms by which they influence age-related neurodegenerative disorders. Also, the review discusses the importance of dietary fiber sources and the challenges associated with harnessing dietary-derived SCFAs as promoters of neurological health in elderly individuals. Overall, this study suggests that gut microbiota-derived SCFAs and/or dietary fibers hold promise as potential targets and strategies for addressing age-related neurodegenerative disorders.

IPA and its precursors differently modulate the proliferation, differentiation, and integrity of intestinal epithelial cells

BACKGROUND/OBJECTIVES

Indole-3-propionic acid (IPA) is a tryptophan-derived microbial metabolite that has been associated with protective effects against inflammatory and metabolic diseases. However, there is a lack of knowledge regarding the effects of IPA under physiological conditions and at the intestinal level.

MATERIALS/METHODS

Human intestinal epithelial Caco-2 cells were treated for 2, 24, and/or 72 h with IPA or its precursors - indole, tryptophan, and propionate - at 1, 10, 100, 250, or 500 μM to assess cell viability, integrity, differentiation, and proliferation.

RESULTS

IPA induced cell proliferation and this effect was associated with a higher expression of extracellular signal-regulated kinase 2 (ERK2) and a lower expression of c-Jun. Although indole and propionate also induced cell proliferation, this involved ERK2 and c-Jun independent mechanisms. On the other hand, both tryptophan and propionate increased cell integrity and reduced the expression of claudin-1, whereas propionate decreased cell differentiation.

CONCLUSIONS

In conclusion, these findings suggested that IPA and its precursors distinctly contribute to the proliferation, differentiation, and barrier function properties of human intestinal epithelial cells. Moreover, the pro-proliferative effect of IPA in intestinal epithelial cells was not explained by its precursors and is rather related to its whole chemical structure. Maintaining IPA at physiological levels, e.g., through IPA-producing commensal bacteria, may be important to preserve the integrity of the intestinal barrier and play an integral role in maintaining metabolic homeostasis.

Fuzi polysaccharides improve immunity in immunosuppressed mouse models by regulating gut microbiota composition

Rationale and objectives

Fuzi, the dried root of Aconitum carmichaelii Debx, is one of the widely used traditional Chinese medicines. Fuzi polysaccharides are considered the most bioactive compounds with immunomodulatory functions, however, the mechanisms have not been evaluated. This study aims to systematically investigate the effects of Fuzi polysaccharides on the gut microbiota and immune function using a mouse model immunosuppressed with cyclophosphamide.

Methods

The short-chain fatty acid levels in cecal contents were measured by gas chromatography-mass spectrometry. The gut microbiota 16S rRNA gene were sequenced by next generation sequencing. The mRNA expression levels of NF-κB, IL-6, TNF-α, iNOS and COX-2 were measured using quantitative real-time polymerase chain reaction. The protein expression of occludin and zonula occludens-1 were analyzed by Western blot. The white blood cells were counted using automated hematology analyzer, and CD4⁺FOXP3⁺/CD4⁺ ratio was measured by flow cytometry.

Results and Conclusions

Fuzi polysaccharides had the function of elevating the concentration of acetic acid, propionic acid, isobutyric acid, and n-butyric acid in the cecum. Meanwhile, Fuzi polysaccharides could decrease the relative abundance of Helicobacter, Anaerotruncus, Faecalibacterium, Lachnospira, Erysipelotrichaceae_UCG-003, Mucispirillum, and Mycoplasma, and increase the relative abundance of Rhodospirillales, Ruminococcaceae_UCG-013, Mollicutes_RF39, Ruminococcus_1, Christensenellaceae_R-7_group, and Muribaculaceae in the gut. Furthermore, Fuzi polysaccharides exhibited the function of increasing spleen and thymus indices and number of white blood cells and lymphocytes. Fuzi polysaccharides could reverse the decreased mRNA expression of NF-кB, IL-6, and iNOS, differentiation of CD4⁺FOXP3⁺ regulatory T cells as well as protein expression of occludin and zonula occludens-1 induced by cyclophosphamide. In addition, the mRNA and protein expression of cytokines were significantly correlated with the abundance of gut microbiota under Fuzi polysaccharides treatment. Collectively, the above results demonstrated that Fuzi polysaccharides could regulate inflammatory cytokines and gut microbiota composition of immunosuppressive mice to improve immunity, thereby shedding light on revealing the molecular mechanism of polysaccharides of traditional Chinese medicines in the future.

Butyrate Protects Barrier Integrity and Suppresses Immune Activation in a Caco-2/PBMC Co-Culture Model While HDAC Inhibition Mimics Butyrate in Restoring Cytokine-Induced Barrier Disruption

Low-grade inflammation and barrier disruption are increasingly acknowledged for their association with non-communicable diseases (NCDs). Short chain fatty acids (SCFAs), especially butyrate, could be a potential treatment because of their combined anti-inflammatory and barrier- protective capacities, but more insight into their mechanism of action is needed. In the present study, non-activated, lipopolysaccharide-activated and αCD3/CD28-activated peripheral blood mononuclear cells (PBMCs) with and without intestinal epithelial cells (IEC) Caco-2 were used to study the effect of butyrate on barrier function, cytokine release and immune cell phenotype. A Caco-2 model was used to compare the capacities of butyrate, propionate and acetate and study their mechanism of action, while investigating the contribution of lipoxygenase (LOX), cyclooxygenase (COX) and histone deacetylase (HDAC) inhibition. Butyrate protected against inflammatory-induced barrier disruption while modulating inflammatory cytokine release by activated PBMCs (interleukin-1 beta↑, tumor necrosis factor alpha↓, interleukin-17a↓, interferon gamma↓, interleukin-10↓) and immune cell phenotype (regulatory T-cells↓, T helper 17 cells↓, T helper 1 cells↓) in the PBMC/Caco-2 co-culture model. Similar suppression of immune activation was shown in absence of IEC. Butyrate, propionate and acetate reduced inflammatory cytokine-induced IEC activation and, in particular, butyrate was capable of fully protecting against cytokine-induced epithelial permeability for a prolonged period. Different HDAC inhibitors could mimic this barrier-protective effect, showing HDAC might be involved in the mechanism of action of butyrate, whereas LOX and COX did not show involvement. These results show the importance of sufficient butyrate levels to maintain intestinal homeostasis.

Impact of Probiotics on the Prevention and Treatment of Gastrointestinal Diseases in the Pediatric Population

Despite the high prevalence of gastrointestinal disorders (GIDs) in infants and children, especially those categorized as functional GIDs (FGIDs), insufficient knowledge about their pathophysiology has limited both symptomatic diagnosis and the development of optimal therapies. Recent advances in the field of probiotics have made their potential use as an interesting therapeutic and preventive strategy against these disorders possible, but further efforts are still needed. In fact, there is great controversy surrounding this topic, generated by the high variety of potential probiotics strains with plausible therapeutic utility, the lack of consensus in their use as well as the few comparative studies available on probiotics that record their efficacy. Taking into account these limitations, and in the absence of clear guidelines about the dose and timeframe for successful probiotic therapy, our review aimed to evaluate current studies on potential use of probiotics for the prevention and treatment of the most common FGIDs and GIDs in the pediatric population. Furthermore, matters referring to know major action pathways and key safety recommendations for probiotic administration proposed by major pediatric health agencies shall also be discussed.

Dietary genistein increases microbiota-derived short chain fatty acid levels, modulates homeostasis of the aging gut, and extends healthspan and lifespan

Age-related gastrointestinal decline contributes to whole-organism frailty and mortality. Genistein is known to have beneficial effects on age-related diseases, but its precise role in homeostasis of the aging gut remains to be elucidated. Here, wild-type aging mice and Zmpste24^-/- progeroid mice were used to investigate the role of genistein in lifespan and homeostasis of the aging gut in mammals. A series of longitudinal, clinically relevant measurements were performed to evaluate the effect of genistein on healthspan. It was found that dietary genistein promoted a healthier and longer life and was associated with a decrease in the levels of systemic inflammatory cytokines in aging mice. Furthermore, dietary genistein ameliorated gut dysfunctions, such as intestinal inflammation, leaky gut, and impaired epithelial regeneration. A distinct genistein-mediated alteration in gut microbiota was observed by increasing Lachnospira abundance and short-chain fatty acid (SCFA) production. Further fecal microbiota transplantation and dirty cage sharing experiments indicated that the gut microbiota from genistein-fed mice rejuvenated the aging gut and extended the lifespan of progeroid mice. It was demonstrated that genistein-associated SCFAs alleviated tumor necrosis factor alpha-induced intestinal organoid damage. Moreover, genistein-associated propionate promoted regulatory T cell-derived interleukin 10 production, which alleviated macrophage-derived inflammation. This study provided the first data, to the authors' knowledge, indicating that dietary genistein modulates homeostasis in the aging gut and extends the healthspan and lifespan of aging mammals. Moreover, the existence of a link between genistein and the gut microbiota provides a rationale for dietary interventions against age-associated frailty.

Folic Acid Protects against Hyperuricemia in C57BL/6J Mice via Ameliorating Gut-Kidney Axis Dysfunction

Emerging lines of research evidence point to a vital role of gut-kidney axis in the development of hyperuricemia (HUA), which has been identified as an increasing burden worldwide due to the high prevalence. The involved crosstalk which links the metabolic and immune-related pathways is mainly responsible for maintaining the axial homeostasis of uric acid (UA) metabolism. Nowadays, the urate-lowering drugs only aim to treat acute gouty arthritis as a result of their controversial clinical application in HUA. In this study, we established the HUA model of C57BL/6J mice to evaluate the effectiveness of folic acid on UA metabolism and further explored the underlying mechanisms. Folic acid attenuated the kidney tissue injury and excretion dysfunction, as well as the typical fibrosis in HUA mice. Molecular docking results also revealed the structure-activity relationship of the folic acid metabolic unit and the UA transporters GLUT9 and URAT1, implying the potential interaction. Also, folic acid alleviated HUA-induced Th17/Treg imbalance and intestinal tissue damage and inhibited the active state of the TLR4/NF-κB signaling pathway, which is closely associated with the circulating LPS level caused by the impaired intestinal permeability. Furthermore, the changes of intestinal microecology induced by HUA were restored by folic acid, including the alteration in the structure and species composition of the gut microbiome community, and metabolite short-chain fatty acids. Collectively, this study revealed that folic acid intervention exerted improving effects on HUA by ameliorating gut-kidney axis dysfunction.

Host-microbiota interactions shaping T-cell response and tolerance in type 1 diabetes

Type-1 Diabetes (T1D) is a complex polygenic autoimmune disorder involving T-cell driven beta-cell destruction leading to hyperglycemia. There is no cure for T1D and patients rely on exogenous insulin administration for disease management. T1D is associated with specific disease susceptible alleles. However, the predisposition to disease development is not solely predicted by them. This is best exemplified by the observation that a monozygotic twin has just a 35% chance of developing T1D after their twin's diagnosis. This makes a strong case for environmental triggers playing an important role in T1D incidence. Multiple studies indicate that commensal gut microbiota and environmental factors that alter their composition might exacerbate or protect against T1D onset. In this review, we discuss recent literature highlighting microbial species associated with T1D. We explore mechanistic studies which propose how some of these microbial species can modulate adaptive immune responses in T1D, with an emphasis on T-cell responses. We cover topics ranging from gut-thymus and gut-pancreas communication, microbial regulation of peripheral tolerance, to molecular mimicry of islet antigens by microbial peptides. In light of the accumulating evidence on commensal influences in neonatal thymocyte development, we also speculate on the link between molecular mimicry and thymic selection in the context of T1D pathogenesis. Finally, we explore how these observations could inform future therapeutic approaches in this disease.

Leaky Gut in IBD: Intestinal Barrier-Gut Microbiota Interaction

Inflammatory bowel disease (IBD) is a global disease that is in increasing incidence. The gut, which contains the largest amount of lymphoid tissue in the human body, as well as a wide range of nervous system components, is integral in ensuring intestinal homeostasis and function. By interacting with gut microbiota, immune cells, and the enteric nervous system, the intestinal barrier, which is a solid barrier, protects the intestinal tract from the external environment, thereby maintaining homeostasis throughout the body. Destruction of the intestinal barrier is referred to as developing a "leaky gut," which causes a series of changes relating to the occurrence of IBD. Changes in the interactions between the intestinal barrier and gut microbiota are particularly crucial in the development of IBD. Exploring the leaky gut and its interaction with the gut microbiota, immune cells, and the neuroimmune system may help further explain the pathogenesis of IBD and provide potential therapeutic methods for future use.

Zinc in sickle cell disease: A narrative review

Sickle cell disease (SCD) is an inherited disease caused by hemoglobin S mutated hemoglobin S. It is characterized by chronic hemolysis, intermittent vaso-occlusive crises followed by ischemia-reperfusion, and organ damage. These patients have an increased risk of multiple micronutrient deficiencies, such as zinc. The reduced zinc bioavailability in sickle cell patients may lead to several complications such as growth retardation, delayed wound healing, increased vaso-occlusive crises, and infections. This narrative review aims to analyze the literature concerning the zinc status in SCD and their possible consequences on the patients' clinical evolution. We found in children and adolescents a direct association between zinc insufficiencies/deficiencies with increased disease severity in SCD. Monitoring zinc status in children and adolescent SCD appears essential for reducing disease-associated morbidity and infections. Zinc supplementation is a safe therapeutic modality for treating SCD patients. New research must be carried out, especially for adults, to ensure more remarkable survival for this population.

The Role of Paracellular Transport in the Intestinal Absorption and Biopharmaceutical Characterization of Minoxidil

The purpose of this study was to evaluate mechanisms behind the intestinal permeability of minoxidil, with special emphasis on paracellular transport, and elucidate the suitability of minoxidil to be a reference drug for Biopharmaceutics Classification System (BCS). The permeability of minoxidil (vs. metoprolol) was evaluated in-silico, in-vitro using both the PAMPA assay and across Caco-2 cell monolayers, as well as in-vivo in rats throughout the entire intestine. The permeability was studied in conditions that represent the different segments of the small intestine: upper jejunum (pH 6.5), mid small intestine (pH 7.0), distal ileum (pH 7.5), and colon (pH 6.5). Since we aimed to investigate the paracellular transport of minoxidil, we have also examined its permeability in the presence of quercetin (250 µM), which closes the tight junctions, and sodium decanoate (10 mM), which opens the tight junctions. While metoprolol demonstrated segmental-dependent rat and PAMPA permeability, with higher permeability in higher pH regions, the permeability of minoxidil was pH-independent. Minoxidil PAMPA permeability was significantly lower than its rat permeability, indicating a potential significant role of the paracellular route. In rat intestinal perfusion studies, and across Caco-2 monolayers, tight junction modifiers significantly affected minoxidil permeability; while the presence of quercetin caused decreased permeability, the presence of sodium decanoate caused an increase in minoxidil permeability. In accordance with these in-vitro and in-vivo results, in-silico simulations indicated that approximatelly 15% of minoxidil dose is absorbed paracellularly, mainly in the proximal parts of the intestine. The results of this study indicate that paracellular transport plays a significant role in the intestinal permeability of minoxidil following oral administration. Since this permeation route may lead to higher variability in comparison to transcellular, these findings diminish the suitability of minoxidil to serve as the low/high BSC permeability class benchmark.

The gut-lung axis in severe acute Pancreatitis-associated lung injury: The protection by the gut microbiota through short-chain fatty acids

The role of gut microbiota in regulating the intestinal homeostasis, as well as the pathogenesis of severe acute pancreatitis-associated lung injury (PALI) is widely recognized. The bioactive functions of metabolites with small molecule weight and the detail molecular mechanisms of PALI mediated by "gut-lung axis" have gradually raised the attentions of researchers. Several studies have proved that short-chain fatty acids (SCFAs) produced by gut microbiome play crucial roles and varied activities in the process of PALI. However, relevant reviews reporting SCFAs in the involvement of PALI is lacking. In this review, we firstly introduced the synthetic and metabolic pathways of SCFAs, as well as the transport and signal transduction routes in brief. Afterwards, we focused on the possible mechanisms and clues of SCFAs to participate in the fight against PALI which referred to the inhibition of pathogen proliferation, anti-inflammatory effects, enhancement of intestinal barrier functions, and the maintenance and regulation of immune homeostasis via pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). In addition, the latest reported pathological and physiological mechanisms of the gut-lung axis involved in PALI were reviewed. Finally, we summarized the potential therapeutic interventions of PALI by targeting SCFAs, including dietary fiber supplementation, direct supplementation of SCFAs/prebiotics/probiotics, and drugs administration, which is expected to provide new sights for clinical use in the future.

Protective Effects of Oxyberberine in 5-Fluorouracil-Induced Intestinal Mucositis in the Mice Model

Berberine (BBR), a major active constituent of Rhizoma coptidis, was reported to exert beneficial effects on intestinal mucositis (IM) induced by 5-fluorouracil (5-FU). However, the bioavailability of BBR is extremely low, and its metabolites were perceived to contribute to its prominent pharmacological activities. Oxyberberine (OBB) is a gut metabolite of BBR, which has been reported to have a superior anti-inflammatory effect in experimental colitis. However, its anti-inflammatory effects against 5-FU-induced IM mice have not yet been investigated. Hence, the purpose of this study was to reveal the protective effects of OBB on IM induced by 5-FU and investigate its potential underlying mechanism. The IM mice model was induced by receiving 5-FU (60 mg/kg, i.p.) for five days. Meanwhile, BBR (50 mg/kg) and OBB (12.5, 25, and 50 mg/kg) were given prior to 30 min intraperitoneal injection of 5-FU for seven days. Results indicated that OBB ameliorated body weight loss, anorexia, diarrhea, and histopathological damage in 5-FU-induced IM mice. After OBB administration, the amounts of MDA, SOD, and GSH altered by IM were remarkably restored. OBB was also observed to dramatically decrease the levels of TNF-α, IL-8, IL-6, COX-2, and iNOS and promote the release of IL-10. Besides, OBB distinctly upregulated the mRNA expressions of PCNA, ZO-1, occludin, and mucin-1, which could improve intestinal homeostasis in IM mice. OBB also blocked the activation of the upstream TLR4/MyD88 signaling pathway, and then it inhibited the phosphorylation of the NF-κB and MAPK pathways. Importantly, compared with BBR, OBB displayed a superior therapeutic effect to BBR in alleviating 5-FU-induced IM mice. These results indicated that OBB has considerable potential to become a novel candidate drug against IM.

Food as Treatment of Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD), namely, Crohn's disease (CD) and ulcerative colitis (UC), are lifelong and incurable chronic inflammatory diseases affecting 6.8 million people worldwide. By 2030, the prevalence of IBD is estimated to reach 1% of the population in Western countries, and thus there is an urgent need to develop effective therapies to reduce the burden of this disease. Microbiome dysbiosis is at the heart of the IBD pathophysiology, and current research and development efforts for IBD treatments have been focused on gut microbiome regulation. Diet can shape the intestinal microbiome. Diet is also preferred over medication, is safe, and has been proven to be an effective strategy for the management of IBD. Therefore, although often overlooked, dietary interventions targeting the microbiome represent ideal treatments for IBD. Here, I summarize the latest research on diet as a treatment for IBD from infancy to adulthood, compile evidence of the mechanisms of action behind diet as treatment, and, lastly, provide insights into future research focusing on culturally tailored diets for ethnic minority groups with increased incidence of IBD yet underrepresented in nutrition research.

Butyrate and propionate restore interleukin 13-compromised esophageal epithelial barrier function

BACKGROUND

Eosinophilic esophagitis (EoE) is a food allergen driven disease that is accompanied by interleukin (IL) 13 overexpression and esophageal barrier dysfunction allowing transepithelial food allergen permeation. Nutraceuticals, such as short-chain fatty acids (SCFAs) that restore barrier function and increase immune fitness may be a promising tool in the management of EoE. Here, we investigated the effects of the SCFAs acetate, propionate, and butyrate on an IL-13-compromised human esophageal epithelial barrier, including the mechanisms involved.

METHODS

An air-liquid interface culture model of differentiated human EPC2-hTERT (EPC2) was used to study whether SCFAs could restore barrier function after IL-13-induced impairment. Esophageal epithelial barrier function was monitored by transepithelial electrical resistance (TEER) and FITC-dextran paracellular flux, and was further examined by qPCR and immunohistochemical analysis. G protein-coupled receptor (GPR) GPR41, GPR43, GPR109a, or histone deacetylase (HDAC) (ant)agonists were used to assess mechanisms of action of SCFAs.

RESULTS

IL-13 stimulation decreased TEER and increased FITC flux, which was counteracted by butyrate and propionate, but not acetate treatment. Barrier proteins FLG and DSG1 mRNA expression was upregulated following butyrate and propionate treatment, whereas expression of eosinophil chemoattractant CCL26 and protease CAPN14 was downregulated. Similarly, butyrate and propionate restored FLG and DSG1 protein expression. Similar effects were observed with an HDAC antagonist but not with GPR agonists.

CONCLUSION

Nutraceuticals butyrate and propionate restore the barrier function of esophageal epithelial cells after an inflammatory insult and may be of therapeutic benefit in the management of EoE.

The hepatoprotective effects of plant-based foods based on the "gut-liver axis": a prospective review

The importance of the "gut-liver axis" in the pathogenesis of liver diseases has been revealed recently; which promotes the process of developing preventive and therapeutic strategies. However, considering that there are still many challenges in the medical treatment of liver diseases, potential preventive dietary intervention may be a good alternative choice. Plant-based foods have received much attention due to their reported health-promoting effects in targeting multiple pathways involved in the pathogenesis of liver diseases as well as the relative safety for general use. Based on the PubMed and Web of Science databases, this review emphatically summarizes the plant-based foods and their chemical constituents with reported effects to impact the LPS/TLR4 signaling pathway of gut-liver axis of various liver diseases, reflecting their health benefits in preventing/alleviating liver diseases. Moreover, some plant-based foods with potential gut-liver effects are specifically analyzed from the reported studies and conclusions. This review intends to provide readers an overview of the current progress in the field of this research topic. We expect to see more hepatoprotective measures for alleviating the current prevalence of liver diseases.

Supplementation of Dietary Quercetin and Vitamin E Promotes the Intestinal Structure and Immune Barrier Integrity in Aged Breeder Hens

In aged animals, the physiological functions of the gastrointestinal tract (GIT) are reduced. Dietary intervention is necessary to re-activate GIT functions. The objective of this study was to investigate the impacts of dietary combination of quercetin (Q) and vitamin E (VE) on the intestinal structure and barrier integrity in aged breeder chickens. A sum of 400 (65-wks-old) Tianfu breeder hens were randomly allotted into four (4) groups with four (4) replicates, and fed with basal diet; basal diet supplemented with 0.4g/kg of Q; basal diet supplemented with 0.2g/kg of VE; and basal diet supplemented with the combination of Q (0.4 g/kg) and VE (0.2 g/kg) for 14 weeks. At the end of the 14^th week, serum and gut segments were collected from eight hens per group for analyses. The results showed that Q+VE exerted synergistic effects on intestinal morphology by promoting villi height and crypt depth (P < 0.05), as well as mitigated the intestinal inflammatory damage of the aged hens, but decreased the concentration of serum D-lactate and diamine oxidase; and increased the levels of secretory immunoglobulin A (sIgA) and Mucin-2 mRNA (P < 0.05). Furthermore, the mRNA expression of intestinal tight junction proteins including occludin, ZO1, and claudin-1 was increased by Q+VE (P < 0.05). Moreover, Q+VE decreased the mRNA expression of the pro-inflammatory genes (TNF-α, IL-6, and IL-1β), and increased the expression of anti-inflammatory genes (IL-10 and IL-4) (P < 0.05). These results were consistent with the mRNA expression of Bax and Bcl-2. In addition, Q+VE protected the small intestinal tract from oxidative damage by increasing the levels of superoxide dismutase, total antioxidant capacity, glutathione peroxidase, catalase (P < 0.05), and the mRNA expression of SOD1 and GPx-2. However, Q+VE decreased malondialdehyde levels in the intestine compared to the control (P < 0.05). These results indicated that dietary Q+VE improved intestinal function in aged breeder hens, by protecting the intestinal structure and integrity. Therefore, Q+VE could act as an anti-aging agent to elevate the physiological functions of the small intestine in chickens.

Concerted action of berberine in the porcine intestinal epithelial model IPEC-J2: Effects on tight junctions and apoptosis

The plant alkaloid berberine has been shown to have many beneficial effects on human health. This has led to its use as a treatment for various cancer types, obesity, and diabetes. Moreover, a described barrier-strengthening effect in human cancer cell lines indicates that it might be useful for the treatment of inflammatory bowel disease. Detailed information regarding its effects on intestinal epithelium remains limited. In our current study, we describe the impact of berberine on a non-transformed porcine small intestinal epithelial cell model, IPEC-J2. Incubation of IPEC-J2 monolayers with berberine revealed dose- and time-dependent effects on barrier properties. A viability assay confirmed the specific effect of berberine on the apoptotic pathway, paralleled by the internalization of the sealing tight-junction (TJ) proteins claudin-1, claudin-3, and occludin within 6 h. Hence, the barrier function of the cells was reduced, as shown by the reduced transepithelial electrical resistance and the increased [3 H]-D-Mannitol flux. A decrease of claudin-1, claudin-3, and occludin expression was also observed after 24 h, whereas ZO-1 expression was not significantly changed. These data indicate an early effect on both cell viability and barrier integrity, followed by a general effect on TJ architecture. The intracellular co-localization of claudin-1 and occludin or claudin-3 and occludin points to an initial induction of apoptosis accompanied by the internalization of sealing TJ proteins. Although barrier strengthening has been reported in cancerogenic epithelial models, our results show a barrier-weakening action, which represents a new aspect of the effect of berberine on epithelia. These results agree with the known toxic potential of plant alkaloids in general and show that berberine is also capable of exerting adverse effects in the intestinal epithelium.

Multiple Micronutrient Supplementation: As a Supportive Therapy in the Treatment of COVID-19

During the infection and treatment of the SARS-CoV-2 viral infection, age and comorbidities play a major role in the successful management of COVID-19. The nutritional status changes which occur in the body vary with the age and underlying conditions and has a vital role in the functioning of the immune system and cellular membrane integrity, thus minimizing the vulnerability to the infection. Considering the data already published by eminent researchers, a few micronutrients have shown outstanding results as supportive therapies in the treatment of viral infections. Micronutrient like zinc improves the membrane barrier integrity, has anti-inflammatory activity, and is involved in antibody production. Vitamin A supports the phagocytic activity of macrophages, while vitamin C reduces the worsening of respiratory tract infections by restoring the dysfunctional epithelial barrier of the lungs. Vitamin D, vitamin E, selenium, and omega-3 fatty acid metabolites play a major role in immunomodulation and in the inhibition of proinflammatory cytokine production. Magnesium is involved in the synthesis of antibodies, while copper, vitamin B12, and folate have significant effects on immune cells. A few researchers suggest that iron supplementation has reduced the risk of acquiring respiratory tract infections in children. As the age of the patient increases, the need for micronutrients increases, thus leading to an imbalanced nutritional status which in turn increases the risk and fatality of the infections. The use of micronutrients in modulating the inflammatory, immune responses, and the epithelial barrier integrity is explored during the treatment of viral infections for faster recovery.

Microbial Metabolite Regulation of Epithelial Cell-Cell Interactions and Barrier Function

Epithelial cells that line tissues such as the intestine serve as the primary barrier to the outside world. Epithelia provide selective permeability in the presence of a large constellation of microbes, termed the microbiota. Recent studies have revealed that the symbiotic relationship between the healthy host and the microbiota includes the regulation of cell–cell interactions at the level of epithelial tight junctions. The most recent findings have identified multiple microbial-derived metabolites that influence intracellular signaling pathways which elicit activities at the epithelial apical junction complex. Here, we review recent findings that place microbiota-derived metabolites as primary regulators of epithelial cell–cell interactions and ultimately mucosal permeability in health and disease.

Micronutrient Improvement of Epithelial Barrier Function in Various Disease States: A Case for Adjuvant Therapy

The published literature makes a very strong case that a wide range of disease morbidity associates with and may in part be due to epithelial barrier leak. An equally large body of published literature substantiates that a diverse group of micronutrients can reduce barrier leak across a wide array of epithelial tissue types, stemming from both cell culture as well as animal and human tissue models. Conversely, micronutrient deficiencies can exacerbate both barrier leak and morbidity. Focusing on zinc, Vitamin A and Vitamin D, this review shows that at concentrations above RDA levels but well below toxicity limits, these micronutrients can induce cell- and tissue-specific molecular-level changes in tight junctional complexes (and by other mechanisms) that reduce barrier leak. An opportunity now exists in critical care—but also medical prophylactic and therapeutic care in general—to consider implementation of select micronutrients at elevated dosages as adjuvant therapeutics in a variety of disease management. This consideration is particularly pointed amidst the COVID-19 pandemic.

Phytogenic Compounds for Enhancing Intestinal Barrier Function in Poultry-A Review

After the European Union ban of antibiotic growth promoters, works on different methods of improving gut health have intensified. The poultry industry is struggling with problems that were previously controlled by antibiotic growth promoters, therefore the search for optimal solutions continues. Simultaneously, there is also increasing social pressure to minimize the use of antibiotics and replace them with alternative feed additives. A variety of available alternatives is considered safe by consumers, among which phytogenics play a significant role. However, there are still some limitations that need to be considered. The most questionable are the issues related to bioavailability, metabolism of plant derivatives in birds, and the difficulty of standardizing commercial products. There is still a need for more evidence-based recommendations for the use of phytogenics in livestock. On the other hand, a positive influence of phytogenic compounds on the health of poultry has been previously described by many researchers and practical application of these compounds has auspicious perspectives in poultry production. Supplementation with phytogenic feed additives has been shown to protect birds from various environmental threats leading to impaired intestinal barrier function. Phytogenic feed additives have the potential to improve the overall structure of intestinal mucosa as well as gut barrier function on a molecular level. Recognition of the phytogenics' effect on the components of the intestinal barrier may enable the selection of the most suitable ones to alleviate negative effects of different agents. This review aims to summarize current knowledge of the influence of various phytogenic constituents on the intestinal barrier and health of poultry.

Sarecycline Demonstrated Reduced Activity Compared to Minocycline against Microbial Species Representing Human Gastrointestinal Microbiota

Prolonged use of broad-spectrum tetracycline antibiotics such as minocycline and doxycycline may significantly alter the gut and skin microbiome leading to dysbiosis. Sarecycline, a narrow-spectrum tetracycline-class antibiotic used for acne treatment, is hypothesized to have minimal impact on the gastrointestinal tract microbiota. We evaluated the effect of sarecycline compared to minocycline against a panel of microorganisms that reflect the diversity of the gut microbiome using in vitro minimum inhibitory concentration (MIC) and time-kill kinetic assays. Compared to minocycline, sarecycline showed less antimicrobial activity indicated by higher MIC against 10 of 12 isolates from the Bacteroidetes phylum, three out of four isolates from Actinobacteria phylum, and five of seven isolates from the Firmicutes phylum, with significantly higher MIC values against Propionibacterium freudenreichii (≥3 dilutions). In time-kill assays, sarecycline demonstrated significantly less activity against Escherichia coli compared to minocycline at all time-points (p < 0.05). Moreover, sarecycline was significantly less effective in inhibiting Candida tropicalis compared to minocycline following 20- and 22-h exposure. Furthermore, sarecycline showed significantly less activity against Lactobacillus paracasei (recently renamed as Lacticaseibacillus paracasei subsp. paracasei) (p = 0.002) and Bifidobacterium adolescentis at 48 h (p = 0.042), when compared to minocycline. Overall, sarecycline demonstrated reduced antimicrobial activity against 79% of the tested gut microorganisms, suggesting that it is less disruptive to gut microbiota compared with minocycline. Further in vivo testing is warranted.

Impact of the clinically approved Petasites hybridus extract Ze 339 on intestinal mechanisms involved in the handling of histamine

In patients with histamine intolerance accumulated or ingested histamine causes a broad range of undesirable symptoms. Food-derived histamine is degraded by intestinal diamine oxidase (DAO) and histamine-N-methyltransferase (HNMT), while the organic cation transporter 3 (OCT3) contributes to the transcellular flux of histamine. Anecdotal evidence from patients with HIT suggests an improvement of symptoms related to histamine intolerance after intake of Ze 339, a lipophilic CO₂-extract prepared from the leaves of Petasites hybridus. Thus, it was the aim of this study to investigate the influence of Ze 339 on DAO, HNMT and OCT3 using Caco-2 and MDCKII cells. Even though Ze 339 reduced mRNA levels of HNMT and DAO, there was no change in protein expression. Ze 339 changed neither the basal release nor the enzymatic activity of DAO. Testing the interaction of Ze 339 with the transcellular histamine transport, we observed a significant increase in the basal to apical flux in presence of high Ze 339 concentrations at the early phases of the experiment. Testing the influence of Ze 339 on OCT3-mediated histamine uptake in overexpressing MDCKII cells revealed a dose-dependent inhibition with an estimated IC₅₀ of 26.9 ug/mL for the extract. In conclusion, we report an effect of Ze 339 on transcellular histamine transport, where inhibition of OCT3 may contribute.

Sodium Butyrate Ameliorates Oxidative Stress-Induced Intestinal Epithelium Barrier Injury and Mitochondrial Damage through AMPK-Mitophagy Pathway

Sodium butyrate has gained increasing attention for its vast beneficial effects. However, whether sodium butyrate could alleviate oxidative stress-induced intestinal dysfunction and mitochondrial damage of piglets and its underlying mechanism remains unclear. The present study used a hydrogen peroxide- (H₂O₂-) induced oxidative stress model to study whether sodium butyrate could alleviate oxidative stress, intestinal epithelium injury, and mitochondrial dysfunction of porcine intestinal epithelial cells (IPEC-J2) in AMPK-mitophagy-dependent pathway. The results indicated that sodium butyrate alleviated the H₂O₂-induced oxidative stress, decreased the level of reactive oxygen species (ROS), increased mitochondrial membrane potential (MMP), mitochondrial DNA (mtDNA), and mRNA expression of genes related to mitochondrial function, and inhibited the release of mitochondrial cytochrome c (Cyt c). Sodium butyrate reduced the protein expression of recombinant NLR family, pyrin domain-containing protein 3 (NLRP3) and fluorescein isothiocyanate dextran 4 kDa (FD4) permeability and increased transepithelial resistance (TER) and the protein expression of tight junction. Sodium butyrate increased the expression of light-chain-associated protein B (LC3B) and Beclin-1, reduced the expression of P62, and enhanced mitophagy. However, the use of AMPK inhibitor or mitophagy inhibitor weakened the protective effect of sodium butyrate on mitochondrial function and intestinal epithelium barrier function and suppressed the induction effect of sodium butyrate on mitophagy. In addition, we also found that after interference with AMPKα, the protective effect of sodium butyrate on IPEC-J2 cells treated with H₂O₂ was suppressed, indicating that AMPKα is necessary for sodium butyrate to exert its protective effect. In summary, these results revealed that sodium butyrate induced mitophagy by activating AMPK, thereby alleviating oxidative stress, intestinal epithelium barrier injury, and mitochondrial dysfunction induced by H₂O₂.

The role of fatty acids in Crohn's disease pathophysiology - An overview

Crohn's disease (CD) is an inflammatory bowel disease (IBD) which is characterized by chronic and relapsing inflammation of the gastrointestinal (GI) tract. The etiology of CD is unknown, but factors such as epithelial barrier dysfunction, immune system imbalance, microbiota dysbiosis and environmental influences are thought to be involved in its pathogenesis. Recent studies have shown that short chain fatty acids (SCFAs) and long chain fatty acids (LCFAs) play a vital role in pathophysiology and development of CD by various mechanisms affecting pro- and anti-inflammatory mediators, and maintaining the intestinal homeostasis and regulation of gene expression. SCFAs and LCFAs activate signaling cascades that control immune functions through interaction with cell surface free fatty acid receptors (FFARs), i.e. FFAR1, FFAR2, FFAR3, and FFAR4. This review highlights the role of fatty acids in maintenance of intestinal and immune homeostasis and supports the supplementation of fatty acids as a promising adjunctive treatment for CD.

Present and Future Therapeutic Approaches to Barrier Dysfunction

There is converging and increasing evidence, but also uncertainty, for the role of abnormal intestinal epithelial barrier function in the origin and development of a growing number of human gastrointestinal and extraintestinal inflammatory disorders, and their related complaints. Despite a vast literature addressing factors and mechanisms underlying changes in intestinal permeability in humans, and its connection to the appearance and severity of clinical symptoms, the ultimate link remains to be established in many cases. Accordingly, there are no directives or clinical guidelines related to the therapeutic management of intestinal permeability disorders that allow health professionals involved in the management of these patients to carry out a consensus treatment based on clinical evidence. Instead, there are multiple pseudoscientific approaches and commercial propaganda scattered on the internet that confuse those affected and health professionals and that often lack scientific rigor. Therefore, in this review we aim to shed light on the different therapeutic options, which include, among others, dietary management, nutraceuticals and medical devices, microbiota and drugs, and epigenetic and exosomes-manipulation, through an objective evaluation of the scientific publications in this field. Advances in the knowledge and management of intestinal permeability will sure enable better options of dealing with this group of common disorders to enhance quality of life of those affected.

Potential Implications of Citrulline and Quercetin on Gut Functioning of Monogastric Animals and Humans: A Comprehensive Review

The importance of gut health in animal welfare and wellbeing is undisputable. The intestinal microbiota plays an essential role in the metabolic, nutritional, physiological, and immunological processes of animals. Therefore, the rapid development of dietary supplements to improve gut functions and homeostasis is imminent. Recent studies have uncovered the beneficial effects of dietary supplements on the immune response, microbiota, gut homeostasis, and intestinal health. The application of citrulline (a functional gut biomarker) and quercetin (a known potent flavonoid) to promote gut functions has gained considerable interest as both bioactive substances possess anti-inflammatory, anti-oxidative, and immunomodulatory properties. Research has demonstrated that both citrulline and quercetin can mediate gut activities by combating disruptions to the intestinal integrity and alterations to the gut microbiota. In addition, citrulline and quercetin play crucial roles in maintaining intestinal immune tolerance and gut health. However, the synergistic benefits which these dietary supplements (citrulline and quercetin) may afford to simultaneously promote gut functions remain to be explored. Therefore, this review summarizes the modulatory effects of citrulline and quercetin on the intestinal integrity and gut microbiota, and further expounds on their potential synergistic roles to attenuate intestinal inflammation and promote gut health.

Epithelial sensing of microbiota-derived signals

The gastrointestinal tract harbors trillions of microbial species, collectively termed the microbiota, which establish a symbiotic relationship with the host. Decades of research have emphasized the necessity of microbial signals in the development, maturation, and function of host physiology. However, changes in the composition or containment of the microbiota have been linked to the development of several chronic inflammatory diseases, including inflammatory bowel diseases. Intestinal epithelial cells (IECs) are in constant contact with the microbiota and are critical for maintaining intestinal homeostasis. Signals from the microbiota are directly sensed by IECs and influence intestinal health by calibrating immune cell responses and fortifying intestinal barrier function. IECs detect commensal microbes through engagement of common pattern recognition receptors or by sensing the production of microbial-derived metabolites. Deficiencies in these microbial-detecting pathways in IECs leads to impaired epithelial barrier function and altered intestinal homeostasis. This Review aims to highlight the pathways by which IECs sense microbiota-derived signals and the necessity of these detection pathways in maintaining epithelial barrier integrity.

A bridge for short-chain fatty acids to affect inflammatory bowel disease, type 1 diabetes, and non-alcoholic fatty liver disease positively: by changing gut barrier

PURPOSE

In previous studies, short-chain fatty acids (SCFAs) have been found to regulate gut microbiota and change gut barrier status, and the potential positive effects of SCFAs on inflammatory bowel disease (IBD), type 1 diabetes mellitus (T1D), and non-alcoholic fatty liver disease (NAFLD) have also been found, but the role of SCFAs in these three diseases is not clear. This review aims to summarize existing evidence on the effects of SCFAs on IBD, T1D, and NHFLD, and correlates them with gut barrier and gut microbiota (gut microbiota barrier).

METHODS

A literature search in PubMed, Web of Science, Springer, and Wiley Online Library up to October 2020 was conducted for all relevant studies published.

RESULTS

This is a retrospective review of 150 applied research articles or reviews. The destruction of gut barrier may promote the development of IBD, T1D, and NAFLD. SCFAs seem to maintain the gut barrier by promoting the growth of intestinal epithelial cells, strengthening the intestinal tight connection, and regulating the activities of gut microbiota and immune cells, which might result possible beneficial effects on the above three diseases at a certain dose.

CONCLUSIONS

Influencing gut barrier health may be a bridge for SCFAs (especially butyrate) to have positive effects on IBD, T1D, and NAFLD. It is expected that this article can provide new ideas for the subsequent research on the treatment of diseases by SCFAs and help SCFAs be better applied to precise and personalized treatment.

Use of Short-Chain Fatty Acids for the Recovery of the Intestinal Epithelial Barrier Affected by Bacterial Toxins

Short-chain fatty acids (SCFAs) are carboxylic acids produced as a result of gut microbial anaerobic fermentation. They activate signaling cascades, acting as ligands of G-protein-coupled receptors, such as GPR41, GPR43, and GPR109A, that can modulate the inflammatory response and increase the intestinal barrier integrity by enhancing the tight junction proteins functions. These junctions, located in the most apical zone of epithelial cells, control the diffusion of ions, macromolecules, and the entry of microorganisms from the intestinal lumen into the tissues. In this sense, several enteric pathogens secrete diverse toxins that interrupt tight junction impermeability, allowing them to invade the intestinal tissue and to favor gastrointestinal colonization. It has been recently demonstrated that SCFAs inhibit the virulence of different enteric pathogens and have protective effects against bacterial colonization. Here, we present an overview of SCFAs production by gut microbiota and their effects on the recovery of intestinal barrier integrity during infections by microorganisms that affect tight junctions. These properties make them excellent candidates in the treatment of infectious diseases that cause damage to the intestinal epithelium.

Oral Mucosa as a Potential Site for Diagnosis and Treatment of Allergic and Autoimmune Diseases

Most prevalent food allergies during early childhood are caused by foods with a high allergenic protein content, such as milk, egg, nuts, or fish. In older subjects, some respiratory allergies progressively lead to food-induced allergic reactions, which can be severe, such as urticaria or asthma. Oral mucosa remodeling has been recently proven to be a feature of severe allergic phenotypes and autoimmune diseases. This remodeling process includes epithelial barrier disruption and the release of inflammatory signals. Although little is known about the immune processes taking place in the oral mucosa, there are a few reports describing the oral mucosa-associated immune system. In this review, we will provide an overview of the recent knowledge about the role of the oral mucosa in food-induced allergic reactions, as well as in severe respiratory allergies or food-induced autoimmune diseases, such as celiac disease.

Short chain fatty acids and its producing organisms: An overlooked therapy for IBD?

The gut microbiome and the intestinal immune system are driving contributors to inflammatory bowel diseases (IBD). Both have an important signalling factor in common: short-chain fatty acids (SCFAs). SCFAs (acetate, propionate and butyrate) are produced by bacterial fermentation in the gut and exert several effects on host metabolism and immune system. This review provides an overview of the current knowledge of these effects, with specific focus on energy metabolism, intestinal barrier, immune system, and disease activity in IBD. To conclude, more research is needed on the cross-feeding mechanisms in the gut microbiome, as well as on the therapeutic potential of SCFAs on different disease models. Also randomized controlled trials and prospective cohort studies should investigate the clinical impact of SCFA administration.

Paracellular Filtration Secretion Driven by Mechanical Force Contributes to Small Intestinal Fluid Dynamics

Studies of fluid secretion by the small intestine are dominated by the coupling with ATP-dependent generation of ion gradients, whereas the contribution of filtration secretion has been overlooked, possibly by the lack of a known mechanistic basis. We measured apical fluid flow and generation of hydrostatic pressure gradients by epithelia of cultured mouse enterocytes, Caco-2 and T-84 cells, and fibroblasts exposed to mechanical force provided by vigorous aeration and in response to ion gradients, inhibitors of ion channels and transporters and in vitro using intact mouse and rat small intestine. We describe herein a paracellular pathway for unidirectional filtration secretion that is driven by mechanical force, requires tight junctions, is independent of ionic and osmotic gradients, generates persistent hydrostatic pressure gradients, and would contribute to the fluid shifts that occur during digestion and diarrhea. Zinc inhibits the flow of fluid and the paracellular marker fluorescein isothyocyanate conjugated dextran (MW = 4 kD) across epithelia of cultured enterocytes (>95%; p < 0.001) and intact small intestine (>40%; p = 0.03). We propose that mechanical force drives fluid secretion through the tight junction complex via a “one-way check valve” that can be regulated. This pathway of filtration secretion complements chloride-coupled fluid secretion during high-volume fluid flow. The role of filtration secretion in the genesis of diarrhea in intact animals needs further study. Our findings may explain a potential linkage between intestinal motility and intestinal fluid dynamics.

Evaluation of Barrier Functions in Human iPSC-Derived Intestinal Epithelium

The small intestine plays roles in the absorption and metabolism of orally administered drugs and chemicals. Tight junctions between intestinal epithelial cells, which form a tight barrier preventing the invasion of pathogens and toxins, are essential components of the intestinal defense system. These intestinal functions have generally been evaluated using established cell lines or primary cells in two-dimensional culture. However, these culture systems have not shown the complexity of the three-dimensional structure and diversity of cell types comprising the intestinal epithelial tissue. Here, we report the generation of intestinal organoids using human induced pluripotent stem cells subjected to sequential treatment with different cytokines and compounds. We further describe the tool for evaluating intestinal barrier functions using organoids as a physiologically relevant human platform.

Zinc Gluconate Induces Potentially Cancer Chemopreventive Activity in Barrett's Esophagus: A Phase 1 Pilot Study

BACKGROUND

Chemopreventive effects of zinc for esophageal cancer have been well documented in animal models. This prospective study explores if a similar, potentially chemopreventive action can be seen in Barrett's esophagus (BE) in humans.

AIMS

To determine if molecular evidence can be obtained potentially indicating zinc's chemopreventive action in Barrett's metaplasia.

METHODS

Patients with a prior BE diagnosis were placed on oral zinc gluconate (14 days of 26.4 mg zinc BID) or a sodium gluconate placebo, prior to their surveillance endoscopy procedure. Biopsies of Barrett's mucosa were then obtained for miRNA and mRNA microarrays, or protein analyses.

RESULTS

Zinc-induced mRNA changes were observed for a large number of transcripts. These included downregulation of transcripts encoding proinflammatory proteins (IL32, IL1β, IL15, IL7R, IL2R, IL15R, IL3R), upregulation of anti-inflammatory mediators (IL1RA), downregulation of transcripts mediating epithelial-to-mesenchymal transition (EMT) (LIF, MYB, LYN, MTA1, SRC, SNAIL1, and TWIST1), and upregulation of transcripts that oppose EMT (BMP7, MTSS1, TRIB3, GRHL1). miRNA arrays showed significant upregulation of seven miRs with tumor suppressor activity (-125b-5P, -132-3P, -548z, -551a, -504, -518, and -34a-5P). Of proteins analyzed by Western blot, increased expression of the pro-apoptotic protein, BAX, and the tight junctional protein, CLAUDIN-7, along with decreased expression of BCL-2 and VEGF-R2 were noteworthy.

CONCLUSIONS

When these mRNA, miRNA, and protein molecular data are considered collectively, a cancer chemopreventive action by zinc in Barrett's metaplasia may be possible for this precancerous esophageal tissue. These results and the extensive prior animal model studies argue for a future prospective clinical trial for this safe, easily-administered, and inexpensive micronutrient, that could determine if a chemopreventive action truly exists.

Berberine in the treatment of ulcerative colitis: A possible pathway through Tuft cells

Ulcerative colitis (UC) is an inflammatory bowel disease with complex pathogenesis, which is affected by genetic factors, intestinal immune status and intestinal microbial homeostasis. Intestinal epithelial barrier defect is crucial to the development of UC. Berberine, extracted from Chinese medicine, can identify bitter taste receptor on intestinal Tuft cells and activate IL-25-ILC2-IL-13 immune pathway to impair damaged intestinal tract by promoting differentiation of intestinal stem cells, which might be a potential approach for the treatment of UC.

Gallic and butyric acids modulated NLRP3 inflammasome markers in a co-culture model of intestinal inflammation

Bioactive compounds from food products made from natural ingredients such as corn and common bean could target the NLRP3 inflammasome, protein scaffolds with a key role in the moderation of intestinal inflammation. This research aimed to evaluate the anti-inflammatory effect from the fermented non-digestible fraction of baked corn and common bean snack (FNDF), and its main components, on the modulation of NLRP3 inflammasome markers in vitro. For this, a THP-1 macrophage/differentiated Caco-2 cell co-culture was used as a model of intestinal inflammation. A disease control (DC) (LPS/human IFN-γ, 10 ng/mL) was compared with FNDF (40-300 μg/mL) and its pure components: gallic (38.85 μM) and butyric acids (6 μM), verbascose (0.06 μM), their mixture, and an anti-inflammatory control (tofacitinib, 5 μM). Compared to DC, FNDF (40 μg/mL) reduced the 48 h-basolateral nitrites (40-60%), IL-1β/IL-18, and TNF-α production. Additionally, it decreased the total reactive oxygen species (36.3%) and nitric oxide synthase (6.9%) activities, increasing superoxide dismutase (228.2%) activity. Compared to NLRP3 positive control, FNDF components decreased NLRP3 markers (caspase-1 activity, IL-1β, and apoptosis). These results highlight NLRP3-anti-inflammatory effects from FNDF components. This is the first report of the NLRP3 inflammasome modulation by digested food matrix components, using a co-culture approach.

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

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

Postbiotics-parabiotics: the new horizons in microbial biotherapy and functional foods

Probiotics have several health benefits by modulating gut microbiome; however, techno-functional limitations such as viability controls have hampered their full potential applications in the food and pharmaceutical sectors. Therefore, the focus is gradually shifting from viable probiotic bacteria towards non-viable paraprobiotics and/or probiotics derived biomolecules, so-called postbiotics. Paraprobiotics and postbiotics are the emerging concepts in the functional foods field because they impart an array of health-promoting properties. Although, these terms are not well defined, however, for time being these terms have been defined as here. The postbiotics are the complex mixture of metabolic products secreted by probiotics in cell-free supernatants such as enzymes, secreted proteins, short chain fatty acids, vitamins, secreted biosurfactants, amino acids, peptides, organic acids, etc. While, the paraprobiotics are the inactivated microbial cells of probiotics (intact or ruptured containing cell components such as peptidoglycans, teichoic acids, surface proteins, etc.) or crude cell extracts (i.e. with complex chemical composition)". However, in many instances postbiotics have been used for whole category of postbiotics and parabiotics. These elicit several advantages over probiotics like; (i) availability in their pure form, (ii) ease in production and storage, (iii) availability of production process for industrial-scale-up, (iv) specific mechanism of action, (v) better accessibility of Microbes Associated Molecular Pattern (MAMP) during recognition and interaction with Pattern Recognition Receptors (PRR) and (vi) more likely to trigger only the targeted responses by specific ligand-receptor interactions. The current review comprehensively summarizes and discussed various methodologies implied to extract, purify, and identification of paraprobiotic and postbiotic compounds and their potential health benefits.

Acute Effects of Butyrate on Induced Hyperpermeability and Tight Junction Protein Expression in Human Colonic Tissues

Intact intestinal barrier function is essential for maintaining intestinal homeostasis. A dysfunctional intestinal barrier can lead to local and systemic inflammation through translocation of luminal antigens and has been associated with a range of health disorders. Butyrate, a short-chain fatty acid derived from microbial fermentation of dietary fibers in the colon, has been described as an intestinal barrier-strengthening agent, although mainly by using in vitro and animal models. This study aimed to investigate butyrate’s ability to prevent intestinal hyperpermeability, induced by the mast cell degranulator Compound 48/80 (C48/80), in human colonic tissues. Colonic biopsies were collected from 16 healthy subjects and intestinal permeability was assessed by Ussing chamber experiments. Furthermore, the expression levels of tight junction-related proteins were determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Pre-treatment with 5 mM butyrate or 25 mM butyrate did not protect the colonic tissue against induced paracellular or transcellular hyperpermeability, measured by FITC-dextran and horseradish peroxidase passage, respectively. Biopsies treated with 25 mM butyrate prior to stimulation with C48/80 showed a reduced expression of claudin 1. In conclusion, this translational ex vivo study did not demonstrate an acute protective effect of butyrate against a chemical insult to the intestinal barrier in healthy humans.

Postbiotics: A novel strategy in food allergy treatment

During the last two decades, the prevalence and severity of clinical appearances of food allergy (FA) have a significant rise. FA derives from a breakdown of immune tolerance. In recent year's clinical evidence have shown that the probiotics have significant influences on FA by improving the immune tolerance. Besides, postbiotics due to their unique characteristics (safe profile, more shelf life, resistance to mammalian enzymes and stable to digestive system conditions), may have safety superiority against their parent live cells and as a novel strategy can be applied for improvement immune tolerance and treatment of FA without any undesirable side-effects or human opportunistic infections, particularly in infants and pediatrics.

The Gastrointestinal Exertional Heat Stroke Paradigm: Pathophysiology, Assessment, Severity, Aetiology and Nutritional Countermeasures

Exertional heat stroke (EHS) is a life-threatening medical condition involving thermoregulatory failure and is the most severe condition along a continuum of heat-related illnesses. Current EHS policy guidance principally advocates a thermoregulatory management approach, despite growing recognition that gastrointestinal (GI) microbial translocation contributes to disease pathophysiology. Contemporary research has focused to understand the relevance of GI barrier integrity and strategies to maintain it during periods of exertional-heat stress. GI barrier integrity can be assessed non-invasively using a variety of in vivo techniques, including active inert mixed-weight molecular probe recovery tests and passive biomarkers indicative of GI structural integrity loss or microbial translocation. Strenuous exercise is strongly characterised to disrupt GI barrier integrity, and aspects of this response correlate with the corresponding magnitude of thermal strain. The aetiology of GI barrier integrity loss following exertional-heat stress is poorly understood, though may directly relate to localised hyperthermia, splanchnic hypoperfusion-mediated ischemic injury, and neuroendocrine-immune alterations. Nutritional countermeasures to maintain GI barrier integrity following exertional-heat stress provide a promising approach to mitigate EHS. The focus of this review is to evaluate: (1) the GI paradigm of exertional heat stroke; (2) techniques to assess GI barrier integrity; (3) typical GI barrier integrity responses to exertional-heat stress; (4) the aetiology of GI barrier integrity loss following exertional-heat stress; and (5) nutritional countermeasures to maintain GI barrier integrity in response to exertional-heat stress.