Polyphenols protect the epithelial barrier function of Caco-2 cells exposed to indomethacin through the modulation of occludin and zonula occludens-1 expression

Cranberry Polyphenols and Prevention against Urinary Tract Infections: New Findings Related to the Integrity and Functionality of Intestinal and Urinary Barriers

This work seeks to generate new knowledge about the mechanisms underlying the protective effects of cranberry against urinary tract infections (UTI). Using Caco-2 cells grown in Transwell inserts as an intestinal barrier model, we found that a cranberry-derived digestive fluid (containing 135 ± 5 mg of phenolic compounds/L) increased transepithelial electrical resistance with respect to control (ΔTEER = 54.5 Ω cm2) and decreased FITC-dextran paracellular transport by about 30%, which was related to the upregulation of the gene expression of tight junction (TJ) proteins (i.e., occludin, zonula occludens-1 [ZO-1], and claudin-2) (∼3-4-fold change with respect to control for claudin-2 and ∼2-3-fold for occludin and ZO-1). Similar protective effects, albeit to a lesser extent, were observed when Caco-2 cells were previously infected with uropathogenic Escherichia coli (UPEC). In a urinary barrier model comprising T24 cells grown in Transwell inserts and either noninfected or UPEC-infected, treatments with the cranberry-derived phenolic metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and phenylacetic acid (PAA) (250 μM) also promoted favorable changes in barrier integrity and permeability. In this line, incubation of noninfected T24 cells with these metabolites induced positive regulatory effects on claudin-2 and ZO-1 expression (∼3.5- and ∼2-fold change with respect to control for DOPAC and ∼1.5- and >2-fold change with respect to control for PAA, respectively). Overall, these results suggest that the protective action of cranberry polyphenols against UTI might involve molecular mechanisms related to the integrity and functionality of the urothelium and intestinal epithelium.

Colon-available mango (poly)phenols exhibit mitigating effects on the intestinal barrier function in human intestinal cell monolayers under inflammatory conditions

This study investigated the impact of in vivo available colon-mango (poly)phenols on stress-induced impairment of intestinal barrier function. Caco-2/HT29-MTX cells were incubated with six extracts of ileal fluid collected pre- and 4-8 h post-mango consumption before being subjected to inflammatory stress. (Poly)phenols in ileal fluids were analysed by UHPLC-HR-MS. Epithelial barrier function was monitored by measurement of trans-epithelial electrical resistance (TEER) and the production of selected inflammatory markers (interleukin-8 (IL-8) and nitric oxide (NO)) and the major mucin of the mucosal layer (MUC2). Post-mango intake ileal fluids contained principally benzoic acids, hydroxybenzenes and galloyl derivatives. There was a high interindividual variability in the levels of these compounds, which was reflected by the degree of variability in the protective effects of individual ileal extracts on inflammatory changes in the treated cell cultures. The 24 h treatment with non-cytotoxic doses of extracts of 4-8 h post-mango intake ileal fluid significantly reduced the TEER decrease in monolayers treated with the inflammatory cytomix. This effect was not associated with changes in IL-8 expression and secretion or claudine-7 expression. The mango derived-ileal fluid extract (IFE) also mitigated cytomix-dependent nitrite secretion, as a proxy of NO production, and the MUC2 reduction observed upon the inflammatory challenge. These insights shed light on the potential protective effect of mango (poly)phenols on the intestinal barrier exposed to inflammatory conditions.

Characterization of the intestinal transport mechanism of polystyrene microplastics (MPs) and the potential inhibitory effect of green tea extracts on MPs intestinal absorption

The aims of the current study included characterizing the intestinal transport mechanism of polystyrene microplastics (MPs) with different charges and sizes in the intestinal epithelial cell model and determining the inhibitory effect of green tea extracts (GTEs) on the intestinal absorption of MPs in Caco-2 cells. The smaller sizes, which included diameters of 0.2 μm, of amine-modified MPs compared to either larger size (1 μm diameter, or carboxylate-MPs (0.2 and 1 μm diameter) significantly lowered the cell viability of caco-2 cells that were measured by MTT assay (p < 0.05). The transported amount (particles/mL of the cell media) of amine-modified MPs by the Caco-2 cell, was not dependent according to the concentrations, energy, or temperature, but it was higher than the carboxylate-modified MPs. The co-treatment of GTEs with the amine-modified MPs inhibited Caco-2 cell cytotoxicity as well as reduced the production of intracellular reactive oxygen species (ROS) in HepG2 generated by the exposure of amine-modified MPs. The GTEs co-treatment also increased trans-epithelial electrical resistances (TEER) and reduced the transportation of Lucifer Yellow via the Caco-2 monolayer compared to only the amine-modified MPs exposure. The GTEs treatment led to a decrease in the number of amine-modified MPs transported to the basal side of the Caco-2 monolayer. The results from our study suggest that the consumption of GTEs could enhance the intestinal barrier function by recovering intestinal epithelial cell damage induced by MPs, which resulted in a decrease of the intestinal absorption of MPs.

Ginsenoside Rk3 Regulates Tryptophan Metabolism along the Brain-Gut Axis by Targeting Tryptophan Hydroxylase and Remodeling the Intestinal Microenvironment to Alleviate Depressive-Like Behavior in Mice

Depression is a neuropsychiatric disease that significantly impacts the physical and mental health of >300 million people worldwide and places a major burden on society. Ginsenosides are the main active ingredient in ginseng and have been proven to have various pharmacological effects on the nervous system. Herein, we investigated the antidepressant effect of ginsenoside Rk3 and its underlying mechanism in a murine model of depression. Rk3 significantly improved depression-like behavior in mice, ameliorated the disturbance of the hypothalamus-pituitary-adrenal axis, and alleviated neuronal damage in the hippocampus and prefrontal cortex of mice. Additionally, Rk3 improved the abnormal metabolism of tryptophan in brain tissue by targeting tryptophan hydroxylase, thereby reducing neuronal apoptosis and synaptic structural damage in the mouse hippocampus and prefrontal cortex. Furthermore, Rk3 reshaped the composition of the gut microbiota of mice and regulated intestinal tryptophan metabolism, which alleviated intestinal barrier damage. Thus, this study provides valuable insights into the role of Rk3 in the tryptophan metabolic cycle along the brain-gut axis, suggesting that Rk3 may have the potential for treating depression.

Effectiveness of Anthocyanin-Rich Sour Cherry Extract on Gliadin-Induced Caco-2 Barrier Damage

Several types of gluten-related disorders are known, in which the common starting point is gluten-induced zonulin release. Zonulin results in varying degrees of increased permeability in certain gluten-related disorders but is largely responsible for the development of further pathogenic processes and symptoms. Therefore, it is important to know the barrier-modulating role of individual nutritional components and to what extent the antioxidant substance supports the protection of gliadin-induced membrane damage with its radical scavenging capacity. We investigated the pH dependence of the gliadin-anthocyanin interaction using UV photometry, during which a concentration-dependent interaction was observed at pH 6.8. The barrier modulatory effect of the anthocyanin-rich sour cherry extract (AC) was analyzed on Caco-2 cell culture with pepsin-trypsin-resistant gliadin (PT-gliadin) exposure by TEER measurement, zonula occludens-1 (ZO-1), and Occludin immunohistochemistry. In addition to the TEER-reducing and TJ-rearranging effects of PT-gliadin, NF-κB activation, an increase in cytokine (TNF-α, IFN-γ, and IL-8) release, and mitochondrial ROS levels were observed. We confirmed the anti-inflammatory, stabilizing, and restoring roles of AC extract during gliadin treatment on the Caco-2 monolayer. The extract was able to significantly reduce cytokine and ROS levels despite the known interaction of the main components of the extract with PT-gliadin.

Dietary Polyphenols, Microbiome, and Multiple Sclerosis: From Molecular Anti-Inflammatory and Neuroprotective Mechanisms to Clinical Evidence

Multiple sclerosis (MS) is a multifactorial, immune-mediated disease caused by complex gene-environment interactions. Dietary factors modulating the inflammatory status through the control of the metabolic and inflammatory pathways and the composition of commensal gut microbiota, are among the main environmental factors involved in the pathogenesis of MS. There is no etiological therapy for MS and the drugs currently used, often accompanied by major side effects, are represented by immunomodulatory substances capable of modifying the course of the disease. For this reason, nowadays, more attention is paid to alternative therapies with natural substances with anti-inflammatory and antioxidant effects, as adjuvants of classical therapies. Among natural substances with beneficial effects on human health, polyphenols are assuming an increasing interest due to their powerful antioxidant, anti-inflammatory, and neuroprotective effects. Beneficial properties of polyphenols on the CNS are achieved through direct effects depending on their ability to cross the blood-brain barrier and indirect effects exerted in part via interaction with the microbiota. The aim of this review is to examine the literature about the molecular mechanism underlying the protective effects of polyphenols in MS achieved by experiments conducted in vitro and in animal models of the disease. Significant data have been accumulated for resveratrol, curcumin, luteolin, quercetin, and hydroxytyrosol, and therefore we will focus on the results obtained with these polyphenols. Clinical evidence for the use of polyphenols as adjuvant therapy in MS is restricted to a smaller number of substances, mainly curcumin and epigallocatechin gallate. In the last part of the review, a clinical trial studying the effects of these polyphenols in MS patients will also be revised.

Protective effects of Acetobacter ghanensis against gliadin toxicity in intestinal epithelial cells with immunoregulatory and gluten-digestive properties

PURPOSE

The aim of this study was to establish whether Acetobacter ghanensis, the probiotic characteristics of which were evaluated previously, attenuates gliadin-induced toxicity in intestinal epithelial cells with gluten-digestive and immunoregulatory properties.

METHODS

A co-culture model of human intestinal epithelial cell (Caco-2) monolayers on top of peripheral blood mononuclear cells (PBMCs) obtained from patients with celiac disease (CD) was established. The gluten-digestive properties of A. ghanensis were determined by checking bacterial growth in a medium containing gluten as the main nitrogen source. The mRNA levels of genes encoding TJ-associated proteins were measured by quantitative real-time PCR (qRT-PCR). The concentrations of IL-6 and TNFα were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

We found that PT-gliadin disrupted intestinal barrier integrity by modulating the expression of TJ-associated genes encoding zonulin (increased by ~ 60%), zonula occludens-1 (ZO-1) (decreased by ~ 22%), and occludin (decreased by ~ 28%) in Caco-2 cells. Furthermore, PT-gliadin treatment in Caco-2 cells was associated with increased concentrations of IL-6 (~ 1.6-fold) and TNFα (~ twofold) from PBMCs. These modulatory effects of PT-gliadin, however, were suppressed when Caco-2 cells were subjected to A. ghanensis in the presence of PT-gliadin. As a factor underlying these protective effects, we showed that A. ghanensis could digest gluten peptides.

CONCLUSIONS

To our knowledge, the current study is the first to demonstrate that A. ghanensis improves intestinal barrier functions by attenuating the modulatory effects of PT-gliadin with immunoregulatory and gluten-digestive properties.

Flavonoid Extract from Seed Residues of Hippophae rhamnoides ssp. sinensis Protects against Alcohol-Induced Intestinal Barrier Dysfunction by Regulating the Nrf2 Pathway

Alcohol has been demonstrated to disrupt intestinal barrier integrity. Some flavonoid compounds that exert antioxidant activity have a protective effect on intestinal barrier function. As an important medicinal and edible plant, sea buckthorn (Hippophae) seeds are rich in flavonoids, but their protective effect on the intestinal barrier has not been reported. In our research, 76 kinds of flavonoids were identified in Hippophae rhamnoides ssp. sinensis seed residue flavonoids (HRSF) by ultra-performance liquid chromatography-tandem mass spectrometry. Kaempferol-3-O-rutinoside, isorhamnetin-3-O-rutinoside, kaempferol-3-O-robinoside-7-O-rhamnoside, isorhamnetin-3-O-2G-rhamnosylrutinoside, quercetin-3-O-rutinoside, (-)-epigallocatechin, and B type of procyanidin were the most abundant substances, accounting for 15.276%, 15.128%, 18.328%, 10.904%, 4.596%, 5.082%, and 10.079% of all identified flavonoids, respectively. Meanwhile, pre-treatment with HRSF was able to prevent alcohol-induced disruption of intestinal barrier integrity through elevating the transepithelial monolayer resistance value, inhibiting the flux of fluorescein isothiocyanate-dextran, and upregulating the mRNA and protein level of TJs (occludin and ZO-1). Furthermore, it was also able to reverse alcohol-induced oxidative stress through suppressing the accumulation of reactive oxygen species and malondialdehyde, improving the glutathione level and superoxide dismutase activity. Finally, the results showed that HRSF pre-treatment effectively elevated the erythroid-related factor 2 mRNA and protein level compared with the alcohol-alone treatment group. Our research was the first to demonstrate that HRSF could prevent alcohol-induced intestinal barrier dysfunction through regulating the Nrf2-mediated pathway in order to attenuate oxidative stress and enhance TJ expression.

Toxicity and Anti-Inflammatory Activity of Phenolic-Rich Extract from Nopalea cochenillifera (Cactaceae): A Preclinical Study on the Prevention of Inflammatory Bowel Diseases

Phenolic compounds have been scientifically recognized as beneficial to intestinal health. The cactus Nopalea cochenillifera, used as anti-inflammatory in traditional medicine, is a rich source of these bioactive compounds. The present study aimed to investigate the phytochemical profile of N. cochenillifera extract and evaluate its acute toxicity and anti-inflammatory effect on 2,4-dinitrobenzenesulfonic acid (DNBS)-induced colitis in rats. The total phenolic content per gram of dry extract was 67.85 mg. Through HPLC-IES-MSⁿ, a total of 25 compounds such as saccharides, organic acids, phenolic acids and flavonoids were characterized. The dose of 2000 mg/kg of extract by an oral route showed no signs of toxicity, mortality or significant changes in biochemical and hematological parameters. Regarding intestinal anti-inflammatory effects, animals were treated with three different doses of extract or sulfasalazine. Macroscopic analysis of the colon indicated that the extract decreased the disease activity index. Levels of IL-1β and TNF-α decreased, IL-10 increased and MDA and MPO enzyme levels decreased when compared with the control group. In addition, a down-regulation of MAPK1/ERK2 and NF-κB p65 pathway markers in colon tissue was observed. The epithelial integrity was improved according to histopathological and immunohistological analysis. Thus, the extract provided strong preclinical evidence of being effective in maintaining the remission of colitis.

Gut Bacterial Indole-3-acetic Acid Induced Immune Promotion Mediates Preventive Effects of Fu Brick Tea Polyphenols on Experimental Colitis

Ulcerative colitis has been consistently associated with gut microbiota imbalance and disturbed immune system. Emerging research suggests a protective function of polyphenols on prevention and treatment of ulcerative colitis, yet underlying mechanisms remain unclear. Fu brick tea, a postfermented tea, contains abundant polyphenols with anti-inflammatory and antioxidant properties. In the present study, we found that prophylactic supplementation of polyphenols extracted from Fu brick tea (FBTP) dose-dependently alleviated colitis symptoms, immune cells infiltration, and pro-inflammatory cytokines secretion in mice suffering dextran sulfate sodium induced murine colitis. FBTP substantially reshaped gut microbiota and promoted microbial transformation of tryptophan into indole-3-acetic acid (I3A), thereafter leading to aryl hydrocarbon receptor (AHR)-mediated protection from colitis through enhanced expressions of IL-22 and tight junction proteins (i.e., ZO-1, occluding and claudin-1) in colon. Multiomics integration analyses revealed strong connections between I3A, tryptophan-metabolizing bacteria, AHR activity, and pathological phenotypes of colitis. Notably, FBTP failed to significantly alleviate colitis symptoms in the absence of gut microbiota, while intragastric administration of I3A could imitate benefits of FBTP on colitis alleviation and intestinal epithelial homeostasis through a direct enhancement in AHR activity in microbiota-depleted mice. These findings further determine the key role of gut microbiota controlled I3A-AHR signaling in mediating the FBTP on colitis alleviation. This study provides the first data proposing the FBTP as a natural prebiotic for colitis alleviation through the gut microbiota-dependent modulation of the AHR pathway. Most importantly, we also identified I3A as a key microbial metabolite targeted by FBTP for exhibiting health-promoting effects.

Leaky Gut and the Ingredients That Help Treat It: A Review

The human body is in daily contact with potentially toxic and infectious substances in the gastrointestinal tract (GIT). The GIT has the most significant load of antigens. The GIT can protect the intestinal integrity by allowing the passage of beneficial agents and blocking the path of harmful substances. Under normal conditions, a healthy intestinal barrier prevents toxic elements from entering the blood stream. However, factors such as stress, an unhealthy diet, excessive alcohol, antibiotics, and drug consumption can compromise the composition of the intestinal microbiota and the homeostasis of the intestinal barrier function of the intestine, leading to increased intestinal permeability. Intestinal hyperpermeability can allow the entry of harmful agents through the junctions of the intestinal epithelium, which pass into the bloodstream and affect various organs and systems. Thus, leaky gut syndrome and intestinal barrier dysfunction are associated with intestinal diseases, such as inflammatory bowel disease and irritable bowel syndrome, as well as extra-intestinal diseases, including heart diseases, obesity, type 1 diabetes mellitus, and celiac disease. Given the relationship between intestinal permeability and numerous conditions, it is convenient to seek an excellent strategy to avoid or reduce the increase in intestinal permeability. The impact of dietary nutrients on barrier function can be crucial for designing new strategies for patients with the pathogenesis of leaky gut-related diseases associated with epithelial barrier dysfunctions. In this review article, the role of functional ingredients is suggested as mediators of leaky gut-related disorders.

The therapeutic potential of quercetin for cigarette smoking-induced chronic obstructive pulmonary disease: a narrative review

Quercetin is a flavonoid with antioxidant and anti-inflammatory properties. Quercetin has potentially beneficial therapeutic effects for several diseases, including cigarette smoking-induced chronic obstructive pulmonary disease (CS-COPD). Many studies have shown that quercetin's antioxidant and anti-inflammatory properties have positive therapeutic potential for CS-COPD. In addition, quercetin's immunomodulatory, anti-cellular senescence, mitochondrial autophagy-modulating, and gut microbiota-modulating effects may also have therapeutic value for CS-COPD. However, there appears to be no review of the possible mechanisms of quercetin for treating CS-COPD. Moreover, the combination of quercetin with common therapeutic drugs for CS-COPD needs further refinement. Therefore, in this article, after introducing the definition and metabolism of quercetin, and its safety, we comprehensively presented the pathogenesis of CS-COPD related to oxidative stress, inflammation, immunity, cellular senescence, mitochondrial autophagy, and gut microbiota. We then reviewed quercetin's anti-CS-COPD effects, performed by influencing these mechanisms. Finally, we explored the possibility of using quercetin with commonly used drugs for treating CS-COPD, providing a basis for future screening of excellent drug combinations for treating CS-COPD. This review has provided meaningful information on quercetin's mechanisms and clinical use in treating CS-COPD.

Effect of dietary licorice flavonoids powder on performance, intestinal immunity and health of weaned piglets

Licorice flavonoids, a bioactive substance derived from glycyrrhiza, have been reported for many pharmacological properties and are beneficial to animal health. This study aimed to explore the effects of licorice flavonoids powder (LFP) on growth performance and intestinal health of piglets. A total of 96 weaned piglets were randomly assigned into four treatments and supplemented with 0, 50, 150 and 250 mg/kg LFP for 5 weeks. Dietary LFP supplementation tended to increase (p = 0.068) average daily gain (ADG) and reduce (p = 0.089) the feed intake/body gain (F/G) of piglets than that of the control group during 15-35 days; and concentrations of LFP supplementation reduced (p < 0.01) diarrhoea index during 14-35 days and 0-35 days. Piglets fed on diets supplied with LFP had a lower (p < 0.05) pH in caecum and colon. Dietary LFP supplementation increased (p < 0.01) the villi height and the ratio of villi height/crypt depth in duodenum, and reduced (p < 0.05) crypt depth in duodenum. Compared with the control group, 250 mg/kg LFP supplementation up-regulated (p < 0.05) the mRNA level of occludin (OCLN) in ileum. Meanwhile, dietary LFP supplementation down-regulated (p < 0.05) mRNA abundance of Interleukin (IL)-1β, IL-8 and induced nitrogen monoxide synthase (INOS) in duodenum. Dietary 150 mg/kg LFP supplementation down-regulated (p < 0.05) mRNA abundance of IL-1β and 250 mg/kg LFP up-regulated (p < 0.05) the expression of IL-10 in ileum. In summary, dietary LFP supplementation has a trend to improve the performance of weaning piglets, those improvements are accompanied by reduction in diarrhoea, enhancement of intestinal morphological structure, barrier function, immune function, and development. In general, 150 mg/kg LFP supplementation is more effective.

Crosstalk between Resveratrol and Gut Barrier: A Review

The plant-based nutraceuticals are receiving increasing interest in recent time. The high attraction to the phytochemicals is associated with their anti-inflammatory and antioxidant activities, which can lead to reduced risk of the development of cardiovascular and other non-communicable diseases. One of the most disseminated groups of plant bioactives are phenolic compounds. It was recently hypothesized that phenolic compounds can have the ability to improve the functioning of the gut barrier. The available studies showed that one of the polyphenols, resveratrol, has great potential to improve the integrity of the gut barrier. Very promising results have been obtained with in vitro and animal models. Still, more clinical trials must be performed to evaluate the effect of resveratrol on the gut barrier, especially in individuals with increased intestinal permeability. Moreover, the interplay between phenolic compounds, intestinal microbiota and gut barrier should be carefully evaluated in the future. Therefore, this review offers an overview of the current knowledge about the interaction between polyphenols with a special emphasis on resveratrol and the gut barrier, summarizes the available methods to evaluate the intestinal permeability, discusses the current research gaps and proposes the directions for future studies in this research area.

Local and systemic effects of microbiome‐derived metabolites

Commensal microbes form distinct ecosystems within their mammalian hosts, collectively termed microbiomes. These indigenous microbial communities broadly expand the genomic and functional repertoire of their host and contribute to the formation of a “meta‐organism.” Importantly, microbiomes exert numerous biochemical reactions synthesizing or modifying multiple bioactive small molecules termed metabolites, which impact their host's physiology in a variety of contexts. Identifying and understanding molecular mechanisms of metabolite–host interactions, and how their disrupted signaling can contribute to diseases, may enable their therapeutic application, a modality termed “postbiotic” therapy. In this review, we highlight key examples of effects of bioactive microbe‐associated metabolites on local, systemic, and immune environments, and discuss how these may impact mammalian physiology and associated disorders. We outline the challenges and perspectives in understanding the potential activity and function of this plethora of microbially associated small molecules as well as possibilities to harness them toward the promotion of personalized precision therapeutic interventions.

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.

Plum Prevents Intestinal and Hepatic Inflammation in the Acute and Chronic Models of Dextran Sulfate Sodium-Induced Mouse Colitis

SCOPE

Inflammatory bowel disease (IBD), including ulcerative colitis (UC), is a chronic recurrent inflammatory disease of the digestive tract and increases the risk of colon cancer.

METHOD AND RESULTS

This study evaluates the effects of dietary intervention with freeze-dried plum (FDP), a natural antioxidant and anti-inflammatory fruit with no toxicity on dextran sulfate sodium (DSS)-induced acute and chronic experimental colitis in a mouse model and studies the molecular mechanisms of protection through the gut-liver axis. The results show that FDP decreases the levels of inflammatory mediators, which is a nitrative stress biomarker in both acute and chronic models. FDP markedly reduces DSS-induced injury to the colonic epithelium in both acute and chronic models. In addition, FDP significantly decreases the levels of pro-oxidant markers such as CYP2E1, iNOS, and nitrated proteins (detected by anti-3-NT antibody) in DSS-induced acute and chronic colonic injury models. Furthermore, FDP markedly reduces markers of liver injury such as serum ALT/AST, antioxidant markers, and inflammatory mediators in DSS-induced acute and chronic colonic injury.

CONCLUSION

These results demonstrate that the FDP exhibits a protective effect on DSS-induced acute and chronic colonic and liver injury through the gut-liver axis via antioxidant and anti-inflammatory properties.

Case ReportPaclitaxel-loaded TPGS2k/Gelatin-grafted Cyclodextrin/Hyaluronic acid-grafted Cyclodextrin nanoparticles for oral bioavailability and targeting enhancement

The clinical applications of paclitaxel (PTX), a natural compound with broad-spectrum antitumor effects, have been markedly limited owing to its poor oral bioavailability and lack of targeting ability. Recently, several drug carriers, such as TPGS_2k, gelatin (Gel), cyclodextrin (CD), and hyaluronic acid (HA), have been identified as promising enhancers of drug efficacy. Therefore, Gel-grafted CD (GEL-CD) and HA-grafted CD (HA-CD) were synthesized via grafting, and PTX-loaded TPGS_2k/GEL-CD/HA-CD nanoparticles (TGHC-PTX-NPs) were successfully prepared using the ultrasonic crushing method. The mean particles size, polydispersity index, and Zeta potential of TGHC-PTX-NPs were 253.57 ± 2.64 nm, 0.13 ± 0.03, and 0.087 ± 0.005 mV, respectively. TGHC-PTX-NPs with an encapsulation efficiency of 61.77 ± 0.47% and a loading capacity of 6.86 ± 0.32% appeared round and uniformly dispersed based on transmission electron microscopy. In vitro release data revealed that TGHC-PTX-NPs had good sustained-release properties. Further, TGHC-PTX-NPs had increased the targeted uptake by HeLa cells as HA can specifically bind to the CD44 receptor at the cell surface, and its intestinal absorption is related to caveolin-mediated endocytosis. The pharmacokinetic results indicated that TGHC-PTX-NPs significantly enhanced the absorption of PTX in vivo compared to the PTX suspension, with a relative bioavailability of 227.21%. Such findings indicate the potential of TGHC-PTX-NPs for numerous clinical applications.

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.

Protective effects of bioactive peptides in foxtail millet protein hydrolysates against experimental colitis in mice

It is of great significance to develop a dietary intervention strategy to prevent inflammatory bowel disease (IBD). A millet-rich diet can ameliorate IBD, but the active ingredients and mechanisms remain to be studied. Our results showed that the oral administration of foxtail millet protein hydrolysates (FMPH) reduced the disease activity index (DAI) score and improved the colon symptoms of dextran sulfate sodium (DSS)-induced colitis mice. FMPH reduced the serum LPS level, increased intestinal ZO-1 and occludin expression, inhibited NF-κB phosphorylation, and reduced the levels of TNF-α and IL-6. Further, FMPH inhibited Th17 cell differentiation, and inhibited inflammasome activation and IL-1β expression through the NLRP3/ASC/caspase-1 pathway. The results on Caco-2 cells confirmed the role of FMPH on tight junction and inflammasomes activation. A total of 2620 peptides were identified in FMPH by UPLC-MS/MS, of which 22 peptides were predicted as potential biopeptides, and the key sequences were LPF, ANP, PY, YW, and IPP. This study supports the effect of a diet rich in millet on the improvement of IBD and provides a scientific basis for the use of millet protein as a functional food to improve intestinal inflammation.

Probiotics, Prebiotics, and Phytogenic Substances for Optimizing Gut Health in Poultry

The gut microbiota has been designated as a hidden metabolic ‘organ’ because of its enormous impact on host metabolism, physiology, nutrition, and immune function. The connection between the intestinal microbiota and their respective host animals is dynamic and, in general, mutually beneficial. This complicated interaction is seen as a determinant of health and disease; thus, intestinal dysbiosis is linked with several metabolic diseases. Therefore, tractable strategies targeting the regulation of intestinal microbiota can control several diseases that are closely related to inflammatory and metabolic disorders. As a result, animal health and performance are improved. One of these strategies is related to dietary supplementation with prebiotics, probiotics, and phytogenic substances. These supplements exert their effects indirectly through manipulation of gut microbiota quality and improvement in intestinal epithelial barrier. Several phytogenic substances, such as berberine, resveratrol, curcumin, carvacrol, thymol, isoflavones and hydrolyzed fibers, have been identified as potential supplements that may also act as welcome means to reduce the usage of antibiotics in feedstock, including poultry farming, through manipulation of the gut microbiome. In addition, these compounds may improve the integrity of tight junctions by controlling tight junction-related proteins and inflammatory signaling pathways in the host animals. In this review, we discuss the role of probiotics, prebiotics, and phytogenic substances in optimizing gut function in poultry.

A flavonoid rich standardized extract of Glycyrrhiza glabra protects intestinal epithelial barrier function and regulates the tight-junction proteins expression

BACKGROUND

Intestinal epithelial barrier dysfunction predisposes to many gastrointestinal, metabolic, and psychological disorders. A flavonoid rich extract of Glycyrrhiza glabra (FREG) has previously been reported to possess anti-inflammatory, antioxidant, and antiulcer properties.

AIM

To investigate the effect of FREG (GutGard^®) on restoring intestinal barrier function in tumor necrosis factor-alpha (TNF-α) stimulated human colonic adenocarcinoma cell monolayer (Caco-2) and 2,4,6-Trinitrobenzenesulfonic acid (TNBS) induced ulcerative colitis in rats.

METHODS

In in vitro, human intestinal Caco-2 cell monolayers were treated with TNF-α in the presence or absence of FREG and the paracellular permeability to FITC-conjugated 4-kD dextran (FD4) was measured to evaluate protection against the barrier dysfunction. In in vivo, intestinal barrier dysfunction was induced in male albino Wistar rats via intrarectal instillation of TNBS. Subsequently, the rats were treated orally with either FREG at 6.25, 12.5, and 25 mg/kg body weight, or Mesacol (250 mg/kg) for 5 days. On day 5, intestinal epithelial permeability was assessed with FD4 leakage into the serum. Also, colonic inflammation, colon morphology, histology and macroscopic score, weight to length ratio were evaluated. The activity of myeloperoxidase (MPO), TNF- α, secretory IgA levels and tight junction proteins expression were evaluated in rat's colon.

RESULTS

FREG protected the intestinal epithelial barrier integrity in human intestinal Caco-2 cells in vitro. FREG administration significantly improved the intestinal epithelial barrier function as evident from significant reduction in FD4 leakage. The colon morphology, histology score, macroscopic score, colon weight to length ratio also indicates beneficial effects of FREG on barrier function. In addition, FREG regulated the tight junction proteins, and markedly decreased TNF-α, MPO levels and significantly increased the secretory IgA levels in TNBS induced colitis rats.

CONCLUSION

The study findings support the protective action of FREG on intestinal epithelial barrier integrity indicating its potential in protecting from implications of leaky gut.

Neuroprotection of chicoric acid in a mouse model of Parkinson's disease involves gut microbiota and TLR4 signaling pathway

Chicoric acid (CA), a polyphenolic acid obtained from chicory and purple coneflower (Echinacea purpurea), has been regarded as a nutraceutical to combat inflammation, viruses and obesity. Parkinson's disease (PD) is a common neurodegenerative disorder, and the microbiota-gut-brain axis might be the potential mechanism in the pathogenesis and development of PD. The results obtained in this study demonstrated that oral pretreatments of CA significantly prevented the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced motor dysfunctions and death of nigrostriatal dopaminergic neurons along with the inhibition of glial hyperactivation and the increment in striatal neurotrophins. 16S rRNA sequence results showed that CA significantly reduced MPTP-induced microbial dysbiosis and partially restored the composition of the gut microbiota to normal, including decreased phylum Bacteroidetes and genera Parabacteroide, as well as increased phylum Firmicutes, genera Lactobacillus and Ruminiclostridium. Besides, CA promoted colonic epithelial integrity and restored normal SCFA production. We also observed that proinflammatory cytokines such as TNF-α and IL-1β in the serum, striatum and colon were reduced by CA, indicating that CA prevented neuroinflammation and gut inflammation, in which the suppression of the TLR4/MyD88/NF-κB signaling pathway might be the underlying molecular mechanism. These findings demonstrated that CA had neuroprotective effects on MPTP-induced PD mice possibly via modulating the gut microbiota and inhibiting inflammation throughout the brain-gut axis.

Intestinal Barrier and Permeability in Health, Obesity and NAFLD

The largest surface of the human body exposed to the external environment is the gut. At this level, the intestinal barrier includes luminal microbes, the mucin layer, gastrointestinal motility and secretion, enterocytes, immune cells, gut vascular barrier, and liver barrier. A healthy intestinal barrier is characterized by the selective permeability of nutrients, metabolites, water, and bacterial products, and processes are governed by cellular, neural, immune, and hormonal factors. Disrupted gut permeability (leaky gut syndrome) can represent a predisposing or aggravating condition in obesity and the metabolically associated liver steatosis (nonalcoholic fatty liver disease, NAFLD). In what follows, we describe the morphological-functional features of the intestinal barrier, the role of major modifiers of the intestinal barrier, and discuss the recent evidence pointing to the key role of intestinal permeability in obesity/NAFLD.

(-)-Epigallocatechin-3-gallate mitigates cyclophosphamide-induced intestinal injury by modulating the tight junctions, inflammation and dysbiosis in mice

Cyclophosphamide (CTX) is an antitumor drug commonly used to treat various cancer types. Unfortunately, its toxic side effects, including gastrointestinal (GI) toxicity, affect treatment compliance and patients' prognosis. Thus, there is a critical need of evaluating strategies that may improve the associated GI toxicity induced by CTX. In this work, we evaluated the capacity of epigallocatechin-3-gallate (EGCG), a major constituent of green tea, to improve the recovery of gut injury induced by CTX in mice. Treatment with CTX for 5 days severely damaged the intestinal structure, increased immune-related cytokines (TNFα, IL-10 and IL-21), reduced the expression levels of tight junction proteins (ZO-1, occludin, claudin-1), induced reactive oxygen species, altered the composition of gut microbiota, and reduced short chain fatty acid levels. EGCG treatment, starting one day after the last CTX dose, significantly improved the intestinal structure, ameliorated gut permeability, and restored ZO-1, occludin and claudin-1 levels. Moreover, EGCG reduced TNFα, IL-10 and IL-21 levels and decreased oxidative stress by regulating the activities of the antioxidant enzymes catalase, superoxide dismutase and glutathione peroxidase. Finally, EGCG treatment restored the composition of gut microbiota and the levels of the short chain fatty acids. In conclusion, these findings indicate that EGCG may function as an effective bioactive compound to minimize CTX-induced GI tract toxicity.

Protection against indomethacin-induced loss of intestinal epithelial barrier function by a quercetin oxidation metabolite present in onion peel: In vitro and in vivo studies

Oxidative stress is directly implicated in the loss of intestinal epithelial barrier function (IEBF) induced by non-steroidal anti-inflammatory drugs (NSAIDs). Previous studies by our research team demonstrated that 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (BZF), a quercetin oxidation metabolite that naturally occurs in onion peels, exhibits an antioxidant potency notably higher than quercetin. Thus, we assessed the potential of BZF and a BZF-rich onion peel aqueous extract (OAE) to protect against the loss of IEBF in Caco-2 cell monolayers and in rats exposed to indomethacin. In vitro, pure BZF and OAE standardized in BZF (100 nM), protected against the drop in transepithelial electrical resistance by 70 - 73%. Likewise, it prevented the increase in fluorescein-isothiocyanate labelled dextran (FITC-dextran) paracellular transport by 74% and oxidative stress by 84 - 86%. In vivo, BZF, given orally at a dose 80 µg/Kg bw as OAE, totally abolished a 30-fold increase in FITC-dextran serum concentration induced by indomethacin. This effect was dose-dependent and largely conserved (85%) when OAE was given 180-min prior to indomethacin. The IEBF-protective effect of OAE was accompanied by a full prevention of the NF-ĸB activation, and the increases in interleukine-8 secretion and myeloperoxidase activity induced by indomethacin. The protection was also associated with a 21-fold increase in Nrf2, and a 7-fold and 9-fold increase in heme oxygenase-1 and NAD(P)H-quinone oxidoreductase 1, respectively. The IEBF-protecting effect of OAE involves, most likely, its dual capacity to activate Nrf2 while inhibiting NF-ĸB activation. The extremely low doses of BZF needed to promote such actions warrants extending its IEBF-protective effects to other NSAIDs.

Gastrointestinal Digestion of a Grape Pomace Extract: Impact on Intestinal Barrier Permeability and Interaction with Gut Microbiome

Grape pomace (GP) is a winemaking by-product rich in polyphenols and fibre. Supplementation with GP extracts has shown potential benefits against oxidative stress- and inflammation-related pathologies. As a new nutritional target, this paper explores the impact of the ingestion of a grape pomace extract on intestinal barrier functionality. A GP extract was sequentially subjected to gastrointestinal and colonic digestion using the dynamic gastrointestinal simulator (simgi^®). This generated two simulated fluids: intestinal-digested extract (IDE) and colonic-digested extract (CDE). The effects of these two fluids on paracellular permeability and the expression of tight junction (TJ) proteins (i.e., zonula occludens-1 (ZO-1) and occludin) were assessed in Caco-2-cell monolayers grown in Transwell^® inserts. The IDE fluid significantly (p < 0.001) reduced the paracellular transport of FITC-dextran with respect to the control, whereas no significant differences (p > 0.05) were found for CDE, which could be due, at least partially, to the pro-leaky effect of the colonic digestion medium. Accordant slight increases in the mRNA levels of both ZO-1 and occludin were observed for IDE, but without statistical significance. Additionally, the colonic fermentation of the GP extract promoted the production of short-chain fatty acids (SCFA) and phenolic metabolites and led to changes in the relative abundance of some bacteria that might affect paracellular permeability. Overall, this paper reports first trends about the effects of grape pomace extracts on intestinal permeability that would require further confirmation in future experiments.

Cystine reduces tight junction permeability and intestinal inflammation induced by oxidative stress in Caco-2 cells

Intestinal oxidative stress produces pro-inflammatory cytokines, which increase tight junction (TJ) permeability, leading to intestinal and systemic inflammation. Cystine (Cys2) is a substrate of glutathione (GSH) and inhibits inflammation, however, it is unclear whether Cys2 locally improves intestinal barrier dysfunction. Thus, we investigated the local effects of Cys2 on oxidative stress-induced TJ permeability and intestinal inflammatory responses. Caco-2 cells were cultured in a Cys2-supplemented medium for 24 h and then treated with H₂O₂ for 2 h. We assessed TJ permeability by measuring transepithelial electrical resistance and the paracellular flux of fluorescein isothiocyanate–dextran 4 kDa. We measured the concentration of Cys2 and GSH after Cys2 pretreatment. The mRNA expression of pro-inflammatory cytokines was assessed. In addition, the levels of TJ proteins were assessed by measuring the expression of TJ proteins in the whole cells and the ratio of TJ proteins in the detergent-insoluble fractions to soluble fractions (IS/S ratio). Cys2 treatment reduced H₂O₂-induced TJ permeability. Cys2 did not change the expression of TJ proteins in the whole cells, however, suppressed the IS/S ratio of claudin-4. Intercellular levels of Cys2 and GSH significantly increased in cells treated with Cys2. Cys2 treatment suppressed the mRNA expression of pro-inflammatory cytokines, and the mRNA levels were significantly correlated with TJ permeability. In conclusion, Cys2 treatment locally reduced oxidative stress-induced intestinal barrier dysfunction possively due to the mitigation of claudin-4 dislocalization. Furthermore, the effect of Cys2 on the improvement of intestinal barrier function is related to the local suppression of oxidative stress-induced pro-inflammatory responses.

Inhibition of α-glucosidases by tea polyphenols in rat intestinal extract and Caco-2 cells grown on Transwell

Inhibition of maltase, sucrase, isomaltase and glucoamylase activity by acarbose, epigallocatechin gallate, epicatechin gallate and four polyphenol-rich tea extract from white, green, oolong, black tea, were investigated by using rat intestinal enzymes and human Caco-2 cells. Regarding rat intestinal enzyme mixture, all four tea extracts were very effective in inhibiting maltase and glucoamylase activity, but only white tea extract inhibited sucrase and isomaltase activity and the inhibition was limited. Mixed-type inhibition on rat maltase activity was observed. Tea extracts in combination with acarbose, produced a synergistic inhibitory effect on rat maltase activity. Caco-2 cells experiments were conducted in Transwells. Green tea extract and epigallocatechin gallate show dose-dependent inhibition on human sucrase activity, but no inhibition on rat sucrase activity. The opposite was observed on maltase activity. The results highlighted the different response in the two investigated model systems and show that tea polyphenols are good inhibitors for α-glucosidase activity.

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.

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.

Antioxidant Analogue 6-Amino-2,4,5-Trimethylpyridin-3-ol Ameliorates Experimental Colitis in Mice

BACKGROUND

Oxidative stress has been suggested to be a factor contributing to the disease severity of inflammatory bowel disease (IBD). BJ-1108, a derivative of 6-amino-2,4,5-trimethylpyridin-3-ol, is reported to significantly inhibit the generation of reactive oxygen species (ROS) in vitro. However, whether this molecule affects intestinal inflammation is largely unknown. We aimed to investigate the effect of BJ-1108 on dextran sulfate sodium (DSS)-induced experimental colitis in mice.

METHODS

Colitis was induced in mice with DSS, and disease severity was estimated by evaluating body weight, colon length, histology, immune cell infiltration, and intestinal permeability. We examined the protective effects of BJ-1108 on barrier function using Caco-2 cells. Last, we estimated the impact of BJ-1108 on the phosphorylation of NF-kB, PI3K/AKT, and mitogen-activated protein kinases.

RESULTS

Mice treated with BJ-1108 exhibited improved disease severity, as indicated by evaluations of body weight, histological scores, spleen weight, and infiltrates of T cells and macrophages. The administration of BJ-1108 inhibited the colonic mRNA expression of IL-6 and IL-1β in vivo. Additionally, BJ-1108 limited intestinal permeability and enhanced the expression of tight junction (TJ) proteins such as claudin-1 and claudin-3 in the DSS-induced colitis model. In an in vitro model using Caco-2 cells, BJ-1108 ameliorated cytokine-induced ROS generation in a dose-dependent manner and remarkably recovered barrier dysfunction as estimated by evaluating transepithelial electrical resistance and TJ protein expression. BJ-1108 suppressed the NF-kB/ERK/PI3K pathway.

CONCLUSIONS

This study demonstrated that BJ-1108 ameliorated intestinal inflammation in an experimental colitis mouse model, suggesting possible therapeutic implications for IBD.

Intestinal pharmacokinetics of resveratrol and regulatory effects of resveratrol metabolites on gut barrier and gut microbiota

Resveratrol, a dietary polyphenol, has a variety of intestinal bioactivities. However, its material basis remains unknown. This study examined the intestinal pharmacokinetics of resveratrol using HPLC-MS/MS. After oral ingestion in mice, resveratrol and its sulfation metabolites were identified in copious amount in the entire intestinal tract and feces. The glucuronidation metabolites were found in major quantity only in the small intestine. The amount of resveratrol and its metabolites in the total intestine peaked at 4 h, with a concentration of 200 ± 74.8 μM, which corresponded to 14.0% of the administrated dose. During in vitro fermentation, resveratrol-3-O-sulfate, but not resveratrol, significantly promoted the growth of Lactobacillus reuteri (10-fold higher). During the incubation with Caco-2 cells, resveratrol-3-O-sulfate significantly up-regulated the mRNA expressions of tight junction and mucin-related proteins. In conclusion, the intestinal concentration of resveratrol could partially support its intestinal bioactivities, which may be mediated through the actions of its metabolites.

The impact of quercetin on a porcine intestinal epithelial cell line exposed to deoxynivalenol

Quercetin (Que) is present in many vegetables and fruits as a secondary antioxidant metabolite. Deoxynivalenol (DON) produced by various Fusarium mould species can induce cytotoxicity and oxidative stress in the gastrointestinal tracts of humans and farm animals. The aim of this study was to investigate the effects of Que on DON-induced oxidative stress in a non-tumourigenic porcine IPEC-J2 cell line. Two experimental designs were used in our experiments as follows: (a) pretreatment with 20 µmol/L Que for 24 h followed by 1-h 1 µmol/L DON treatment and (b) simultaneous application of 20 µmol/L Que and 1 µmol/L DON for 1 h. Cell cytotoxicity, transepithelial electrical resistance (TER) of cell monolayers and extracellular/intracellular redox status were studied. It was found that DON significantly decreased TER and triggered oxidative stress, while Que pretreatments were beneficial in maintaining the integrity of the monolayers and alleviated oxidative stress. However, co-treatment with Que was unable to preserve the integrity and redox balance of the cells exposed to DON. These results indicate that only the 24-h preincubation of cells with 20 µmol/L Que was beneficial in compensating for the disruption caused by DON in extracellular oxidative status.

Quercetin Oxidation Metabolite Present in Onion Peel Protects Caco-2 Cells against the Oxidative Stress, NF-kB Activation, and Loss of Epithelial Barrier Function Induced by NSAIDs

The potential of 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (BZF), a quercetin oxidation metabolite, and that of a BZF-rich onion peel aqueous extract (OAE) to protect Caco-2 monolayers against the oxidative stress (OS) and an increased permeability (IP) induced by five nonsteroidal anti-inflammatory drugs (NSAIDs) (indomethacin, diclofenac, piroxicam, ibuprofen, and metamizole) were investigated. Under identical OS conditions, the NSAIDs substantially differed in their ability to induce an IP and/or NF-kB activation. The OAE (100 nM BZF) protected in identical magnitude (84-86%) against OS but in a highly dissimilar manner against the IP (18-73%). While all NSAIDs activated NF-kB, the OAE prevented only that induced by indomethacin. Results reveal that the IP has no direct relationship with the OS and that with the exception of indomethacin, the prevention of NSAIDs-induced OS and/or NF-kB activation plays no fundamental role in the IP-protecting effect of OAE. These results warrant the in vivo evaluation of OAE against indomethacin-induced loss of intestinal barrier function.

Natural Polyphenols as Targeted Modulators in Colon Cancer: Molecular Mechanisms and Applications

Colon cancer commonly develops from long-term chronic inflammation in the intestine and seriously threatens human health. Natural polyphenols have been valued as a crucial regulator of nutrient metabolism and metabolic diseases, owing to their anti-inflammatory and antioxidant functions and the ability to maintain a balance between gut microbes and their hosts. Notably, experimental and clinical evidence has shown that natural polyphenols could act as a targeted modulator to play a key role in the prevention or treatment of colon cancer. Thus, in this review, we summarized recent advances in the possible regulatory mechanism and the potential application of natural polyphenols in colon cancer, which might be regarded as a novel platform for the colon cancer management.

Effects of a tart cherry (Prunus cerasus L.) phenolic extract on Porphyromonas gingivalis and its ability to impair the oral epithelial barrier

Periodontal diseases, including gingivitis and periodontitis, are a global oral health problem. Porphyromonas gingivalis, a key pathogen involved in the onset of periodontitis, is able to colonize the subgingival epithelium and invade the underlying connective tissue due to the contribution of cysteine proteases known as gingipains. In this study, we investigated the effects of a phenolic extract prepared from tart cherry (Prunus cerasus L.) juice on the growth, adherence, and protease activity of P. gingivalis. We also assessed the protective effect of the tart cherry extract on the disruption of the oral epithelial barrier induced by P. gingivalis. The tart cherry extract that contains procyanidins and quercetin and its derivatives (rutinoside, glucoside) as the most important phenolic compounds attenuated P. gingivalis growth, reduced adherence to an experimental basement membrane matrix model, and decreased the protease activities of P. gingivalis. The tart cherry extract also exerted a protective effect on the integrity of the oral epithelial barrier in an in vitro model infected with P. gingivalis. More specifically, the extract prevented a decrease in transepithelial electrical resistance as well as the destruction of tight junction proteins (zonula occludens-1 and occludin). These results suggest that the tart cherry phenolic extract may be a promising natural product for the treatment of periodontitis through its ability to attenuate the virulence properties of P. gingivalis and curtail the ability of this pathogen to impair the oral epithelial barrier.

Preventative and Therapeutic Potential of Flavonoids in Peptic Ulcers

Peptic ulcer disease is a common gastrointestinal tract disorder that affects up to 20% of the population of the world. Treatment of peptic ulcer remains challenging due to the limited effectiveness and severe side effects of the currently available drugs. Hence, natural compounds, owing to their medicinal, ecological, and other safe properties, are becoming popular potential candidates in preventing and treating peptic ulcers. Flavonoids, the most abundant polyphenols in plants, exhibit gastroprotective effects against peptic ulcer both in vivo and in vitro. In this review, we summarized the anti-ulcer functions and mechanisms, and also the bioavailability, efficacy, and safety, of flavonoid monomers in the gastrointestinal tract. Flavonoids exerted cytoprotective and rehabilitative effects by not only strengthening defense factors, such as mucus and prostaglandins, but also protecting against potentially harmful factors via their antioxidative, anti-inflammatory, and antibacterial activities. Although controlled clinical studies are limited at present, flavonoids have shown a promising preventable and therapeutic potential in peptic ulcers.

Heat treatment of galangin and kaempferol inhibits their benefits to improve barrier function in rat intestinal epithelial cells

Flavonols are bioactive substances in plant foods. In this study, two flavonols galangin and kaempferol were heated at 100°C for 30 min prior to assessing their effects on barrier function of rat intestinal epithelial (IEC-6) cells. Both heated and unheated flavonols (2.5-20 µmol/L dosages) were nontoxic to the cells up to 48 h post-treatment, and could promote cell viability values to 102.2-141.2% of control. By treatment with 5 µmol/L flavonols for 24 and 48 h, the treated cells time-dependently showed better improved physical and biological barrier functions than the control cells without any flavonol treatment, including higher transepithelial electrical resistance and antibacterial effect but reduced paracellular permeability and bacterial translocation. The results from real-time PCR and western-blot assays indicated that the cells treated with heated and unheated flavonols of 5 µmol/L dosage had up-regulated mRNA (1.13-1.81 folds) and protein (1.15-5.11 folds) expression for zonula occluden-1, occludin, and claudin-1 that are vital to the tight junctions of the cells. Moreover, protein expression of RhoA and ROCK were down-regulated into 0.41-0.98 and 0.40-0.92 folds, respectively, demonstrating a Rho inactivation that led to enhanced cell barrier integrity via the RhoA/ROCK pathway. Overall, galangin was more active than kaempferol to perform three biofunctions like improving cell barrier function, up-regulating tight junctions protein expression, and down-regulating RhoA/ROCK expression. Moreover, the heated flavonols were less effective than the unheated counterparts to perform these biofunctions. It is concluded that this heat treatment of galangin and kaempferol could inhibit their benefits to improve barrier function of IEC-6 cells.

p-Cymene and Rosmarinic Acid Ameliorate TNBS-Induced Intestinal Inflammation Upkeeping ZO-1 and MUC-2: Role of Antioxidant System and Immunomodulation

p-Cymene (p-C) and rosmarinic acid (RA) are secondary metabolites that are present in medicinal herbs and Mediterranean spices that have promising anti-inflammatory properties. This study aimed to evaluate their intestinal anti-inflammatory activity in the trinitrobenzene sulphonic acid (TNBS)-induced colitis model in rats. p-C and RA (25-200 mg/kg) oral administration reduced the macroscopic lesion score, ulcerative area, intestinal weight/length ratio, and diarrheal index in TNBS-treated animals. Both compounds (200 mg/kg) decreased malondialdehyde (MDA) and myeloperoxidase (MPO), restored glutathione (GSH) levels, and enhanced fluorescence intensity of superoxide dismutase (SOD). They also decreased interleukin (IL)-1β and tumor necrosis factor (TNF)-α, and maintained IL-10 basal levels. Furthermore, they modulated T cell populations (cluster of differentiation (CD)4+, CD8+, or CD3+CD4+CD25+) analyzed from the spleen, mesenteric lymph nodes, and colon samples, and also decreased cyclooxigenase 2 (COX-2), interferon (IFN)-γ, inducible nitric oxide synthase (iNOS), and nuclear transcription factor kappa B subunit p65 (NFκB-p65) mRNA transcription, but only p-C interfered in the suppressor of cytokine signaling 3 (SOCS3) expression in inflamed colons. An increase in gene expression and positive cells immunostained for mucin type 2 (MUC-2) and zonula occludens 1 (ZO-1) was observed. Altogether, these results indicate intestinal anti-inflammatory activity of p-C and RA involving the cytoprotection of the intestinal barrier, maintaining the mucus layer, and preserving communicating junctions, as well as through modulation of the antioxidant and immunomodulatory systems.

Anti-inflammatory activities of green tea catechins along the gut-liver axis in nonalcoholic fatty liver disease: lessons learned from preclinical and human studies

Nonalcoholic fatty liver disease (NAFLD), which is the most prevalent hepatic disorder worldwide, affecting 25% of the general population, describes a spectrum of progressive liver conditions ranging from relatively benign liver steatosis and advancing to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Hallmark features of NASH are fatty hepatocytes and inflammatory cell infiltrates in association with increased activation of hepatic nuclear factor kappa-B (NFκB) that exacerbates liver injury. Because no pharmacological treatments exist for NAFLD, emphasis has been placed on dietary approaches to manage NASH risk. Anti-inflammatory bioactivities of catechin-rich green tea extract (GTE) have been well-studied, especially in preclinical models that have detailed its effects on inflammatory responses downstream of NFκB activation. This review will therefore discuss the experimental evidence that has advanced an understanding of the mechanisms by which GTE, either directly through its catechins or potentially indirectly through microbiota-derived metabolites, limits NFκB activation and NASH-associated liver injury. Specifically, it will describe the hepatic-level benefits of GTE that attenuate intracellular redox distress and pro-inflammatory signaling from extracellular receptors that otherwise activate NFκB. In addition, it will discuss the anti-inflammatory activities of GTE on gut barrier function as well as prebiotic and antimicrobial effects on gut microbial ecology that help to limit the translocation of gut-derived endotoxins (e.g. lipopolysaccharides) to the liver where they otherwise upregulate NFκB activation by Toll-like receptor-4 signaling. This summary is therefore expected to advance research translation of the hepatic- and intestinal-level benefits of GTE and its catechins to help manage NAFLD-associated morbidity.

Interactions of dietary polyphenols with epithelial lipids: advances from membrane and cell models in the study of polyphenol absorption, transport and delivery to the epithelium

Currently, diet-related diseases such as diabetes, obesity, hypertension, and cardiovascular diseases account for 70% of all global deaths. To counteract the rising prevalence of non-communicable diseases governments are investing in persuasive educational campaigns toward the ingestion of fresh fruits and vegetables. The intake of dietary polyphenols abundant in Mediterranean and Nordic-type diets holds great potential as nutritional strategies in the management of diet-related diseases. However, the successful implementation of healthy nutritional strategies relies on a pleasant sensory perception in the mouth able to persuade consumers to adopt polyphenol-rich diets and on a deeper understanding on the chemical modifications, that affect not only their chemical properties but also their physical interaction with epithelial lipids and in turn their permeability, location within the lipid bilayer, toxicity and biological activity, and fate during absorption at the gastro-intestinal epithelium, transport in circulation and delivery to the endothelium. In this paper, we review the current knowledge on the interactions between polyphenols and their metabolites with membrane lipids in artificial membranes and epithelial cell models (oral, stomach, gut and endothelium) and the findings from polyphenol-lipid interactions to physiological processes such as oral taste perception, gastrointestinal absorption and endothelial health. Finally, we discuss the limitations and challenges associated with the current experimental approaches in membrane and cell model studies and the potential of polyphenol-rich diets in the quest for personalized nutritional strategies ("personalized nutrition") to assist in the prevention, treatment, and management of non-communicable diseases in an increasingly aged population.

Resveratrol attenuates the pathogenic and inflammatory properties of Porphyromonas gingivalis

Porphyromonas gingivalis has been strongly associated with chronic periodontitis, which affects tooth-supporting tissues. This Gram-negative anaerobic bacterium produces a repertoire of virulence factors that modulate tissue destruction directly or indirectly by the induction of inflammatory processes. The aim of this study was to investigate the effects of resveratrol, a major polyphenol found in grapes and wine, on the growth and virulence properties of P. gingivalis as well as on gingival keratinocyte tight junction integrity and the host inflammatory response. Resveratrol exhibited antibacterial activity that may result from damage to the bacterial cell membrane. Resveratrol also killed a pre-formed P. gingivalis biofilm and reduced bacterial adherence to matrix proteins. In addition, resveratrol had a protective effect on the integrity of the keratinocyte tight junctions by inhibiting its breakdown by P. gingivalis. This may be related to the ability of resveratrol to inhibit the protease activities of P. gingivalis. Lastly, resveratrol reduced P. gingivalis-mediated activation of the NF-κB signaling pathway and attenuated TREM-1 gene expression as well as soluble TREM-1 secretion in monocytes. The effect on NF-κB activation likely results from the ability of resveratrol to act as a PPAR-γ agonist. In summary, the antibacterial, anti-adherence, and antiprotease properties of resveratrol, as well as its ability to protect the gingival keratinocyte barrier and attenuate the inflammatory response in monocytes suggest that it may be a promising novel therapeutic agent for treating periodontal disease.

Pomegranate Mesocarp against Colitis-Induced Visceral Pain in Rats: Effects of a Decoction and Its Fractions

The management of chronic visceral pain related to Inflammatory Bowel Diseases or Irritable Bowel Syndrome is still a clinical problem and new therapeutic strategies continue to be investigated. In the present study, the efficacy of a pomegranate decoction and of its polysaccharide and ellagitannin components in preventing the development of colitis-induced abdominal pain in rats was evaluated. After colitis induction by 2,4-dinitrobenzenesulfonic acid (DNBS), the pomegranate decoction (300 mg kg-1), polysaccharides (300 mg kg-1), and ellagitannins (45 mg kg-1) were orally administered for 14 days. Repeated treatment with decoction reduced visceral hypersensitivity in the colitic animals both at 7 and 14 days. Similar efficacy was shown by polysaccharides, but with lower potency. Ellagitannins administered at dose equivalent to decoction content showed higher efficacy in reducing the development of visceral pain. Macroscopic and microscopic evaluations performed on the colon 14 days after the damage showed that all three preparations reduced the overall amount of mast cells, the number of degranulated mast cells, and the density of collagen fibers in the mucosal stroma. Although ellagitannins seem to be responsible for most of the beneficial effects of pomegranate on DNBS-induced colitis, the polysaccharides support and enhance its effect. Therefore, pomegranate mesocarp preparations could represent a complementary approach to conventional therapies for promoting abdominal pain relief.

Dietary polyphenol impact on gut health and microbiota

Polyphenols are naturally occurring compounds in plants and they are the most abundant antioxidants in the human diet. Due to their considerable structural diversity, this largely influences their bioavailability. Since a large proportion of polyphenols remains unabsorbed along the gastrointestinal tract, they may accumulate in the large intestine, where most of them are extensively metabolized by the intestinal microbiota. The formation of bioactive polyphenol-derived metabolites may also benefit the health status of the subjects, although the mechanisms have not been delineated. This review aims to highlight the impact of polyphenols on gut health and the modes of action could be through modulation of intestinal barrier function, innate and adaptive immune response, signaling pathways, as well as the ability to modify gut microbiota composition. The review will conclude by presenting future perspective and challenges of polyphenols application in food products to be used for preventing or treating diseases.