Altered paracellular permeability in intestinal cell monolayer challenged with lipopolysaccharide: Modulatory effects of pterostilbene metabolites

Therapeutic potential of Lacticaseibacillus rhamnosus grx10 and its derived postbiotic through gut microbiota and MAPK/MLCK/MLC pathway-mediated intestinal barrier repairment in ulcerative colitis

Lacticaseibacillus rhamnosus grx10 (grx10) has shown promising potential in promoting intestinal health as predicted by genomic and metabolomic analyses. Given the increasing prevalence of ulcerative colitis (UC) and the limitations of existing treatments, exploring alternative therapeutic strategies is essential. This study explored the therapeutic effects and underlying mechanisms of grx10 and its derived postbiotic (P-grx10) in a mouse model of dextran sulfate sodium (DSS)-induced chronic UC. The intervention with grx10 and P-grx10 significantly alleviated clinical symptoms and improved biochemical markers in UC mice. These effects included reducing the disease activity index (DAI), improving colon length and histopathological damage, decreasing the secretion of inflammatory cytokines, and preventing the reduction of antioxidant enzymes. Additionally, grx10 and P-grx10 downregulated key proteins in the Mitogen-Activated Protein Kinase (MAPK)/myosin light chain kinase (MLCK)/myosin light chain (MLC) pathway, prevented the dissociation of tight junction (TJ) proteins and E-cadherin, reduced intestinal permeability, and restored the integrity of the intestinal barrier. Furthermore, both grx10 and P-grx10 modulated the composition and abundance of gut microbiota, helping to maintain intestinal microbiome homeostasis. In conclusion, this study provided evidence regarding the role of grx10 and P-grx10 in alleviating intestinal barrier dysfunction associated with UC and restoring gut microbiota balance. Notably, P-grx10 exhibited higher anti-inflammatory activity and better restoration of intestinal barrier function, whereas the live probiotic grx10 showed a stronger regulatory effect on the gut microbiota. These findings suggest that grx10 and P-grx10 could serve as promising nutritional adjunct therapies for UC, providing novel insights into the distinct roles of probiotic and its derived postbiotic in UC treatment.

Pterostilbene Targets Hallmarks of Aging in the Gene Expression Landscape in Blood of Healthy Rats

SCOPE

Polyphenols from the phytoestrogen group, including pterostilbene (PTS), are known for their antioxidant, anti-inflammatory, and anti-cancer effects. In recent reports, phytoestrogens attenuate age-related diseases; however, their pro-longevity effects in healthy models in mammals remain unknown. As longevity research demonstrates age-related transcriptomic signatures in human blood, the current study hypothesizes that phytoestrogen-supplemented diet may induce changes in gene expression that ultimately confer pro-longevity benefits.

METHODS AND RESULTS

In the present study, RNA sequencing is conducted to determine transcriptome-wide changes in gene expression in whole blood of healthy rats consuming diets supplemented with phytoestrogens. Ortholog cell deconvolution is applied to analyze the omics data. The study discovered that PTS leads to changes in the gene expression landscape and PTS-target genes are associated with functions counteracting hallmarks of aging, including genomic instability, epigenetic alterations, compromised autophagy, mitochondrial dysfunction, deregulated nutrient sensing, altered intercellular interaction, and loss of proteostasis. These functions bridge together under anti-inflammatory effects through multiple pathways, including immunometabolism, where changes in cellular metabolism (e.g., ribosome biogenesis) impact the immune system.

CONCLUSION

The findings provide a rationale for pre-clinical and clinical longevity studies and encourage investigations on PTS in maintaining cellular homeostasis, decelerating the process of aging, and improving conditions with chronic inflammation.

Milk-derived Lactobacillus with high production of short-chain fatty acids relieves antibiotic-induced diarrhea in mice

Antibiotic-associated diarrhea (AAD) is a common side effect during antibiotic treatment, and this has warranted research into alternative protocols. In this study, we investigated the potential therapeutic effects of three cohorts, Lactobacillus plantarum KLDS 1.0386, Lactobacillus acidophilus KLDS 1.0901 and a mixed strain of both, on intestinal inflammation, the intestinal mucosal barrier, and microbial community in mice with ampicillin-induced diarrhea. The results showed that Lactobacillus inhibited the activation of the TLR4/NF-κB signaling pathway, decreased the expression of pro-inflammatory cytokines, increased the expression of anti-inflammatory cytokines in the murine intestine, and alleviated the intestinal barrier damage and inflammation induced by ampicillin. In addition, Lactobacillus ameliorates intestinal epithelial barrier damage by increasing the expression of tight junction proteins and aquaporins. After Lactobacillus treatment, the diversity of gut microbiota increased significantly, and the composition and function of gut microbiota gradually recovered. In the gut microbiota, Bacteroidetes and Escherichia Shigella related to the synthesis of short-chain fatty acids (SCFAs) were significantly affected by ampicillin, while Lactobacillus regulates the cascade of the microbial-SCFA signaling pathway, which greatly promoted the generation of SCFAs. Collectively, Lactobacillus showed better results in treating AAD, especially in mixed strains.

Unveiling the oral-gut connection: chronic apical periodontitis accelerates atherosclerosis via gut microbiota dysbiosis and altered metabolites in apoE-/- Mice on a high-fat diet

The aim of this study was to explore the impact of chronic apical periodontitis (CAP) on atherosclerosis in apoE-/- mice fed high-fat diet (HFD). This investigation focused on the gut microbiota, metabolites, and intestinal barrier function to uncover potential links between oral health and cardiovascular disease (CVD). In this study, CAP was shown to exacerbate atherosclerosis in HFD-fed apoE-/- mice, as evidenced by the increase in plaque size and volume in the aortic walls observed via Oil Red O staining. 16S rRNA sequencing revealed significant alterations in the gut microbiota, with harmful bacterial species thriving while beneficial species declining. Metabolomic profiling indicated disruptions in lipid metabolism and primary bile acid synthesis, leading to elevated levels of taurochenodeoxycholic acid (TCDCA), taurocholic acid (TCA), and tauroursodeoxycholic acid (TDCA). These metabolic shifts may contribute to atherosclerosis development. Furthermore, impaired intestinal barrier function, characterized by reduced mucin expression and disrupted tight junction proteins, was observed. The increased intestinal permeability observed was positively correlated with the severity of atherosclerotic lesions, highlighting the importance of the intestinal barrier in cardiovascular health. In conclusion, this research underscores the intricate interplay among oral health, gut microbiota composition, metabolite profiles, and CVD incidence. These findings emphasize the importance of maintaining good oral hygiene as a potential preventive measure against cardiovascular issues, as well as the need for further investigations into the intricate mechanisms linking oral health, gut microbiota, and metabolic pathways in CVD development.

Protective effect of hydroxytyrosol and tyrosol metabolites in LPS-induced vascular barrier derangement in vitro

Introduction

The maintenance of endothelial barrier function is essential for vasal homeostasis and prevention of cardiovascular diseases. Among the toxic stimuli involved in the initiation of atherosclerotic lesions, Gram negative lipopolysaccharide (LPS) has been reported to be able to trigger endothelial dysfunction, through the alteration of barrier permeability and inflammatory response. Hydroxytyrosol (HT) and tyrosol (Tyr), the major phenolic compounds of extra virgin olive oil (EVOO), as wells as their circulating sulphated and glucuronidated metabolites have been shown to exert anti-inflammatory effects at endothelial level.

Methods

In this study we investigated the protective effects of HT and Tyr metabolites on LPS-induced alteration of permeability in Human Umbilical Vein Endothelial Cells (HUVEC) monolayers and examined underlying signaling pathways, focusing on tight junction (TJ) proteins, mitogen-activated protein kinase (MAPK) and NOD-, LRR-and pyrin domain-containing protein 3 (NLRP3) inflammasome activation.

Results

It was shown that LPS-increased permeability in HUVEC cells was due to the alteration of TJ protein level, following the activation of MAPK and NLRP3. HT and Tyr sulphated and glucuronidated metabolites were able to limit the effects exerted by LPS, acting as signaling molecules with an efficacy comparable to that of their precursors HT and Tyr.

Discussion

The obtained results add a further piece to the understanding of HT and Tyr metabolites mechanisms of action in vascular protection.

Hypoglycemic effects and associated mechanisms of resveratrol and related stilbenes in diet

Hyperglycemia has become a global health problem due to changes in diet and lifestyle. Most importantly, persistent hyperglycemia can eventually develop into type II diabetes. While the usage of current drugs is limited by their side effects, stilbenes derived from fruits and herbal/dietary plants are considered as important phytochemicals with potential hypoglycemic properties. Herein, the most common stilbenoids in consumed foods, i.e. resveratrol, pterostilbene, piceatannol, oxyresveratrol, and 2,3,5,4'-tetrahydroxystilbene-2-O-β-glucopyranoside (THSG), are reviewed in this paper. These stilbenes are found to regulate glucose homeostasis via (a) modulation of feeding behaviour and nutrition absorption; (b) restoration of insulin signalling by enhancing insulin production/insulin sensitivity; (c) improvement of gut permeability, gut microbial profile and resulting metabolomes; and (d) amelioration of circadian rhythm disruption. In this review, we have summarized the underlying mechanisms for the hypoglycemic effects of the five most common dietary stilbenoids listed above, providing a comprehensive framework for future study and applications.

Coffee Leaf Tea Extracts Improve Hyperuricemia Nephropathy and Its Associated Negative Effect in Gut Microbiota and Amino Acid Metabolism in Rats

Hyperuricemia nephropathy (HN) is a metabolic disease characterized by tubular damage, tubulointerstitial fibrosis, and uric acid kidney stones and has been demonstrated to be associated with hyperuricemia. Coffee leaf tea is drunk as a functional beverage. However, its prevention effects on HN remain to be explored. This study showed that coffee leaf tea extracts (TE) contain 19 polyphenols, with a total content of 550.15 ± 27.58 mg GAE/g. TE decreased serum uric acid levels via inhibiting XOD activities and modulating the expression of urate transporters (GLUT9, OAT3, and ABCG2) in HN rats. TE prevented HN-induced liver and kidney damage and attenuated renal fibrosis. Moreover, it upregulated the abundance of SCFA-producing bacteria (Phascolarctobacterium, Alloprevotella, and Butyricicoccus) in the gut and reversed the amino acid-related metabolism disorder caused by HN. TE also decreased the circulating LPS and d-lactate levels and increased the fecal SCFA levels. This study supported the preliminary and indicative effect of coffee leaf tea in the prevention of hyperuricemia and HN.

Dietary protocatechuic acid redistributes tight junction proteins by targeting Rho-associated protein kinase to improve intestinal barrier function

Inflammatory bowel disease (IBD) is continuously increasing globally and caused by intestinal barrier dysfunction. Although protocatechuic acid (PCA) has a protective effect on colitis, the molecular mechanisms underlying its contribution to intestinal barrier function remain unknown. Transepithelial electrical resistance (TEER) and FITC-dextran permeability measurements reveled that PCA suppresses lipopolysaccharide (LPS) and tumor necrosis factor (TNF)-α-induced increase in intestinal permeability; zonula occludens (ZO)-1 and claudin-2 redistribution was also suppressed in the epithelial cell membranes of differentiated Caco-2 cells. PCA was found to directly bind Rho-associated coiled-coil containing protein kinase (ROCK), subsequently suppressing myosin light chain (MLC) phosphorylation. Notably, PCA binds ROCK to a similar degree as Y27632, a selective ROCK inhibitor. Orally administering PCA (5 or 25 mg per kg per day) to C57BL/6 mice alleviated the 3% dextran sulfate sodium (DSS)-induced colitis symptoms including reduced colon length, disrupted intestinal barrier structure, and increased proinflammatory cytokines expressions, such as interleukin (IL)-1β, TNF-α, and IL-6. Furthermore, orally administering PCA suppressed DSS-induced ZO-1 and claudin-2/4 redistribution in mice colon membrane fractions. Therefore, PCA may serve as a promising nutraceutical to improve gut health and alleviate IBD by maintaining intestinal barrier function in vitro and in vivo.

Design, Synthesis, and Antiviral Activities of New Benzotriazole-Based Derivatives

Several human diseases are caused by enteroviruses and are currently clinically untreatable, pushing the research to identify new antivirals. A notable number of benzo[d][1,2,3]triazol-1(2)-yl derivatives were designed, synthesized, and in vitro evaluated for cytotoxicity and antiviral activity against a wide spectrum of RNA positive- and negative-sense viruses. Five of them (11b, 18e, 41a, 43a, 99b) emerged for their selective antiviral activity against Coxsackievirus B5, a human enteroviruses member among the Picornaviridae family. The EC50 values ranged between 6 and 18.5 μM. Among all derivatives, compounds 18e and 43a were interestingly active against CVB5 and were selected to better define the safety profile on cell monolayers by transepithelial resistance test (TEER). Results indicated compound 18e as the hit compound to investigate the potential mechanism of action by apoptosis assay, virucidal activity test, and the time of addition assay. CVB5 is known to be cytotoxic by inducing apoptosis in infected cells; in this study, compound 18e was proved to protect cells from viral infection. Notably, cells were mostly protected when pre-treated with derivative 18e, which had, however, no virucidal activity. From the performed biological assays, compound 18e turned out to be non-cytotoxic as well as cell protective against CVB5 infection, with a mechanism of action ascribable to an interaction on the early phase of infection, by hijacking the viral attachment process.

Probiotic lactobacilli attenuate oxysterols-induced alteration of intestinal epithelial cell monolayer permeability: Focus on tight junction modulation

Oxidative stress and inflammation lead by dietary oxidised lipids, as oxysterols, have been linked to the loss of intestinal barrier integrity, a crucial event in the initiation and progression of intestinal disorders. In the last decade, probiotic lactobacilli have emerged as an interesting tool to improve intestinal health, thanks to their antioxidant and anti-inflammatory properties. The aim of the present study was to evaluate the ability of two commercial probiotic strains of lactobacilli (Lactiplantibacillus plantarum 299v® (DMS 9843) and Lacticaseibacillus casei DG® (CNCMI-1572)), both as live bacteria and intracellular content, to attenuate the oxysterols-induced alteration of intestinal epithelial Caco-2 cell monolayer permeability. Our investigation was focused on the modulation of tight junctions (TJs) proteins, occludin, ZO-1 and JAM-A, in relation to redox-sensitive MAPK p38 activation. Obtained results provided evidence on the ability of the two probiotics to counteract the alteration of monolayer permeability and loss of TJs proteins, at least in part, through the modulation of p38 pathway. The protective action was exerted by live bacteria, whose adhesion to Caco-2 cells was not altered by oxysterols, and bacterial intracellular components equally able to interact with the signaling pathway.

Role of Dietary Polyphenols in the Activity and Expression of Nitric Oxide Synthases: A Review

Nitric oxide (NO) plays several key roles in the functionality of an organism, and it is usually released in numerous organs and tissues. There are mainly three isoforms of the enzyme that produce NO starting from the metabolism of arginine, namely endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and neuronal nitric oxide synthase (nNOS). The expression and activity of these isoforms depends on the activation/deactivation of different signaling pathways at an intracellular level following different physiological and pathological stimuli. Compounds of natural origin such as polyphenols, which are obtainable through diet, have been widely studied in recent years in in vivo and in vitro investigations for their ability to induce or inhibit NO release, depending on the tissue. In this review, we aim to disclose the scientific evidence relating to the activity of the main dietary polyphenols in the modulation of the intracellular pathways involved in the expression and/or functionality of the NOS isoforms.

Direct Action of Non-Digestible Oligosaccharides against a Leaky Gut

The epithelial monolayer is the primary determinant of mucosal barrier function, and tight junction (TJ) complexes seal the paracellular space between the adjacent epithelial cells and represent the main "gate-keepers" of the paracellular route. Impaired TJ functionality results in increased permeation of the "pro-inflammatory" luminal contents to the circulation that induces local and systemic inflammatory and immune responses, ultimately triggering and/or perpetuating (chronic) systemic inflammatory disorders. Increased gut leakiness is associated with intestinal and systemic disease states such as inflammatory bowel disease and neurodegenerative diseases such as Parkinson's disease. Modulation of TJ dynamics is an appealing strategy aiming at inflammatory conditions associated with compromised intestinal epithelial function. Recently there has been a growing interest in nutraceuticals, particularly in non-digestible oligosaccharides (NDOs). NDOs confer innumerable health benefits via microbiome-shaping and gut microbiota-related immune responses, including enhancement of epithelial barrier integrity. Emerging evidence supports that NDOs also exert health-beneficial effects on microbiota independently via direct interactions with intestinal epithelial and immune cells. Among these valuable features, NDOs promote barrier function by directly regulating TJs via AMPK-, PKC-, MAPK-, and TLR-associated pathways. This review provides a comprehensive overview of the epithelial barrier-protective effects of different NDOs with a special focus on their microbiota-independent modulation of TJs.

Pterostilbene attenuates intestinal epithelial barrier loss induced by high loading intensity of exercise

Mounting evidence suggested that high loading intensity of exercise might be detrimental to human health, especially the gastrointestinal tract. Pterostilbene (PTE), derived from grapes and blueberries, might reach a high concentration of intestinal contents. Our study aimed to evaluate PTE’s ability to prevent the loss of intestinal epithelial barrier in high loading intensity of exercise. The exercise model was established by the forced running of mice. An effective HPLC-UV method was developed to quantify PTE concentration in intestinal content. The mRNA changes were detected by quantitative polymerase chain reaction (qPCR). The structure of intestinal flora was analyzed by 16S rRNA sequencing. The PTE (100 mg/kg/d) could significantly attenuate exercise-induced intestinal epithelial barrier loss. Moreover, the HPLC-UV assay showed that the PTE concentration of intestinal content could last 12 h. Furthermore, the exercise increased the abundance of Alistipes, which was related to lipopolysaccharide (LPS) production but could not be reversed by PTE intervention. Besides, cell experiments showed that PTE could promote the expression of intestinal epithelial tight junction (TJ) molecules in vitro. In conclusion, PTE has a significant interest in preventing exercise-induced intestinal damage.

The Anti-Obesity and Anti-Inflammatory Capabilities of Pterostilbene and its Colonic Metabolite Pinostilbene Protect against Tight Junction Disruption from Western Diet Feeding

SCOPE

Tight junctions (TJs) are a member of the intestinal epithelium barrier that provides the first line of protection against external factors. Anti-obesity and protective effects of pterostilbene (PSB) on TJs have previously been reported, but the effect of its colonic metabolite, pinostilbene (PIN), is less understood.

METHODS AND RESULTS

A 16-week animal model fed with western-diet to induced colonic TJs disruption was designed, supplemented with PSB and PIN to evaluate their potent in colonic TJ protection. The results showed that both PSB and PIN exerted suppressive effects on obesity, hepatic steatosis, and chronic inflammation in western-diet-fed mice. Western-diet feeding significantly reduced expression of TJ proteins, including ZO-1, occludin, and claudin-1, while PSB and PIN supplementation effectively protected TJ proteins against disruption. Increment in serum, hepatic, and mesenteric pro-inflammatory cytokines suggest their probable involvement in TJ disruption supported with the findings in macrophage polarization. The adverse were revered by PSB and PIN. The protective effect of PSB and PIN on TJ proteins may stem from their anti-inflammation capabilities.

CONCLUSION

This is the first study suggesting that PIN, the metabolite of PSB, demonstrates a similar protective effect on colonic TJ proteins via its anti-obesity, hepatic protection and anti-inflammatory capabilities. This article is protected by copyright. All rights reserved.

Staphylococcal Enterotoxin A Induces Intestinal Barrier Dysfunction and Activates NLRP3 Inflammasome via NF-κB/MAPK Signaling Pathways in Mice

Staphylococcal enterotoxin A (SEA), the toxin protein secreted by Staphylococcus aureus, can cause staphylococcal food poisoning outbreaks and seriously threaten global public health. However, little is known about the pathogenesis of SEA in staphylococcal foodborne diseases. In this study, the effect of SEA on intestinal barrier injury and NLRP3 inflammasome activation was investigated by exposing BALB/c mice to SEA with increasing doses and a potential toxic mechanism was elucidated. Our findings suggested that SEA exposure provoked villi injury and suppressed the expression of ZO-1 and occludin proteins, thereby inducing intestinal barrier dysfunction and small intestinal injury in mice. Concurrently, SEA significantly up-regulated the expression of NLRP3 inflammasome-associated proteins and triggered the mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB) signaling pathways in jejunum tissues. Notably, selective inhibitors of MAPKs and NF-κB p65 ameliorated the activation of NLRP3 inflammasome stimulated by SEA, which further indicated that SEA could activate NLRP3 inflammasome through NF-κB/MAPK pathways. In summary, SEA was first confirmed to induce intestinal barrier dysfunction and activate NLRP3 inflammasome via NF-κB/MAPK signaling pathways. These findings will contribute to a more comprehensive understanding of the pathogenesis of SEA and related drug-screening for the treatment and prevention of bacteriotoxin-caused foodborne diseases via targeting specific pathways.

Procyanidin A1 and its digestive products prevent acrylamide-induced intestinal barrier dysfunction via the MAPK-mediated MLCK pathway

Procyanidins can alleviate small-intestine damage induced by acrylamide (ACR). However, little is known about whether procyanidins, after gastrointestinal digestion, can prevent ACR-induced intestinal barrier damage and the possible mechanism. Here, Caco-2 cells were differentiated into an intestinal epithelial cell monolayer membrane, which was stimulated with or without ACR in the presence or absence of procyanidin A₁ (A₁) and its digestive products (D-A₁). Our findings show that both A₁ and D-A₁ significantly increased the transepithelial electrical resistance (TEER) value; decreased FITC-dextran 4 kDa (FITC-4 kDa) permeability, apoptosis and lactic dehydrogenase (LDH) release; and enhanced the expression of claudin-1, occludin and zonula occludens-1 (ZO-1) in ACR-induced Caco-2 cell monolayer membrane. In addition, A₁ and D-A₁ suppressed ACR-induced phosphorylation of mitogen-activated protein kinase (MAPK). Finally, A₁ and D-A₁ inhibited the myosin light chain kinase (MLCK) signaling pathway, thereby maintaining normal intestinal barrier functions, similar to the MLCK inhibitor in ACR-induced Caco-2 cell monolayer membrane. These findings indicate that A₁ can alleviate ACR-induced intestinal barrier dysfunction via inhibiting the MAPK/MLCK signaling pathway, and it still has excellent inhibitory effects after digestion.

Allicin Ameliorates Intestinal Barrier Damage via Microbiota-Regulated Short-Chain Fatty Acids-TLR4/MyD88/NF-κB Cascade Response in Acrylamide-Induced Rats

Acrylamide (AA) is a heat-induced toxicant, which can cause severe damage to health. In the present study, SD rats were used to investigate the potential therapeutic effects of allicin dietary supplementation in the rats with AA-induced intestinal injury. The elevated expression of occludin, claudin-1, zonula occludens-1 (ZO-1), mucin 2, and mucin 3 indicated that oral allicin alleviated the intestinal epithelial barrier breakage induced by AA, compared with the AA-treated group. In the gut microbiota, Bacteroides, Escherichia_Shigella, Dubosiella, and Alloprevotella related to the synthesis of short-chain fatty acids (SCFAs) were negatively affected by AA, while allicin regulated cascade response of the microbiota-SCFAs signaling to reverse the reduction of acetic acid and propionic acid by AA treatment. Allicin also dramatically down-regulated the expression of Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), NF-κB signaling pathway proteins, and proinflammatory cytokines by promoting the production of SCFAs in AA-treated rats. Allicin relieved the intestinal barrier injury and inflammation caused by AA as evidenced by the regulation cascade response of the microbiota-SCFAs-TLR4/MyD88/NF-κB signaling pathway. In conclusion, allicin is highly effective in the treatment and prevention of AA-induced intestinal injury.

Ferulic Acid Metabolites Attenuate LPS-Induced Inflammatory Response in Enterocyte-like Cells

Ferulic acid (FA) is a polyphenol pertaining to the class of hydroxycinnamic acids present in numerous foods of a plant origin. Its dietary consumption leads to the formation of several phase I and II metabolites in vivo, which represent the largest amount of ferulates in the circulation and in the intestine in comparison with FA itself. In this work, we evaluated their efficacy against the proinflammatory effects induced by lipopolysaccharide (LPS) in intestinal Caco-2 cell monolayers, as well as the mechanisms underlying their protective action. LPS-induced overexpression of proinflammatory enzymes such as inducible nitric oxide synthase (iNOS) and the consequent hyperproduction of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) were limited by physiological relevant concentrations (1 µM) of FA, its derivatives isoferulic acid (IFA) and dihydroferulic acid (DHFA), and their glucuronidated and sulfated metabolites, which acted upstream by limiting the activation of MAPK p38 and ERK and of Akt kinase, thus decreasing the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-ĸB) translocation into the nucleus. Furthermore, the compounds were found to promote the expression of Nrf2, which may have contributed to the downregulation of NF-ĸB activity. The overall data show that phase I/II metabolites retain the efficacy of their dietary free form in contrasting inflammatory response.

Recent Advances in Health Benefits of Stilbenoids

Biological targeting or molecular targeting is the main strategy in drug development and disease prevention. However, the problem of "off-targets" cannot be neglected. Naturally derived drugs are preferred over synthetic compounds in pharmaceutical markets, and the main goals are high effectiveness, lower cost, and fewer side effects. Single-target drug binding may be the major cause of failure, as the pathogenesis of diseases is predominantly multifactorial. Naturally derived drugs are advantageous because they are expected to have multitarget effects, but not off-targets, in disease prevention or therapeutic actions. The capability of phytochemicals to modulate molecular signals in numerous diseases has been widely discussed. Among them, stilbenoids, especially resveratrol, have been well-studied, along with their potential molecular targets, including AMPK, Sirt1, NF-κB, PKC, Nrf2, and PPARs. The analogues of resveratrol, pterostilbene, and hydroxylated-pterostilbene may have similar, if not more, potential biological targeting effects compared with their original counterpart. Furthermore, new targets that have been discussed in recent studies are reviewed in this paper.

Herbal Medicine, Gut Microbiota, and COVID-19

Coronavirus Disease 19 (COVID-19) is a respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has grown to a worldwide pandemic with substantial mortality. The symptoms of COVID-19 range from mild flu-like symptoms, including cough and fever, to life threatening complications. There are still quite a number of patients with COVID-19 showed enteric symptoms including nausea, vomiting, and diarrhea. The gastrointestinal tract may be one of the target organs of SARS-CoV-2. Angiotensin converting enzyme 2 (ACE2) is the main receptor of SARS-CoV-2 virus, which is significantly expressed in intestinal cells. ACE2 links amino acid malnutrition to microbial ecology and intestinal inflammation. Intestinal flora imbalance and endotoxemia may accelerate the progression of COVID-19. Many herbs have demonstrated properties relevant to the treatment of COVID-19, by supporting organs and systems of the body affected by the virus. Herbs can restore the structure of the intestinal flora, which may further modulate the immune function after SARS-CoV-2 infection. Regulation of intestinal flora by herbal medicine may be helpful for the treatment and recovery of the disease. Understanding the role of herbs that regulate intestinal flora in fighting respiratory virus infections and maintaining intestinal flora balance can provide new ideas for preventing and treating COVID-19.

Effects of Wine and Its Microbial-Derived Metabolites on Intestinal Permeability Using Simulated Gastrointestinal Digestion/Colonic Fermentation and Caco-2 Intestinal Cell Models

This paper explores the effects of wine polyphenols on intestinal permeability in in vitro conditions. A red wine (2500 mg/L of gallic acid equivalents) was sequentially subjected to gastrointestinal and colonic digestion in the Dynamic Gastrointestinal Simulator (simgi^®) to obtain two simulated fluids: intestinal-digested wine (IDW) and colonic-digested wine (CDW). The two fluids were incubated with Caco-2 cell monolayers grown in Transwell^® inserts, and paracellular permeability was measured as transport of FITC-dextran. Non-significant decreases (p > 0.05) in paracellular permeability were found, which was attributed to the relatively low phenolic concentration in the solutions tested (15.6 and 7.8 mg of gallic acid equivalents/L for IDW and CDW, respectively) as quercetin (200 µM) and one of its microbial-derived phenolic metabolites, 3,4-dihydroxyphenylacetic acid (200 µM), led to significant decreases (p < 0.05). The expression of tight junction (TJ) proteins (i.e., ZO-1 and occludin) in Caco-2 cells after incubation with IDW and CDW was also determined. A slight increase in mRNA levels for occludin for both IDW and CDW fluids, albeit without statistical significance (p > 0.05), was observed. Analysis of the microbiome and microbial activity during wine colonic fermentation revealed relevant changes in the relative abundance of some families/genera (i.e., reduction in Bacteroides and an increase in Veillonella, Escherichia/Shigella and Akkermansia) as well as in the microbial production of SCFA (i.e., a significant increase in propionic acid in the presence of IDW), all of which might affect paracellular permeability. Both direct and indirect (microbiota-mediated) mechanisms might be involved in the protective effects of (wine) polyphenols on intestinal barrier integrity. Overall, this paper reinforces (wine) polyphenols as a promising dietary strategy to improve gut functionality, although further studies are needed to evaluate the effect on the intestinal barrier under different conditions.

Ferulic Acid Derivatives and Avenanthramides Modulate Endothelial Function through Maintenance of Nitric Oxide Balance in HUVEC Cells

Wholegrain oats contain a variety of phenolic compounds thought to help maintain healthy vascular function, through the maintenance of local levels of the vasodilator nitric oxide (NO). Thus, the full molecular mechanisms involved are not yet clear. With this work we aim to understand the possible cellular mechanisms by which avenanthramides and ferulic acid derivatives, present in oats, may help maintain a healthy vascular function through the modulation of the NO pathway. Primary Human Umbilical Vein Endothelial Cells (HUVEC) were exposed to ferulic acid, isoferulic acid, hydroferulic acid, ferulic acid 4-O-glucuronide, isoferulic acid 3-O-sulfate, dihydroferulic acid 4-O-glucuronide, avenanthramide A, avenanthramide B and avenanthramide C (1 μM) or vehicle (methanol) for 24 h. Apocynin and Nω-Nitro-L-arginine (L-NNA) were additionally included as controls. NO and cyclic GMP (cGMP) levels, superoxide production and the activation of the Akt1/eNOS pathway were assessed. The statistical analysis was performed using one-way ANOVA followed by a Tukey post-hoc t-test. Apocynin and all phenolic compounds increased NO levels in HUVEC cells (increased DAF2-DA fluorescence and cGMP), and significantly reduced superoxide levels. Protein expression results highlighted an increase in the Akt1 activation state, and increased eNOS expression. Overall, our results indicated that the glucuronide metabolites do not enhance NO production through the Akt1/eNOS pathway, thus all compounds tested are able to reduce NO degradation through reduced superoxide formation.

Cichorium pumilum Jacq Extract Inhibits LPS-Induced Inflammation via MAPK Signaling Pathway and Protects Rats From Hepatic Fibrosis Caused by Abnormalities in the Gut-Liver Axis

The development of liver fibrosis is closely related to the gut microbiota, and the "gut-liver axis" is the most important connection between the two. ethyl acetate extract of Cichorium pumilum Jacq (CGEA) is an herbal extract consisting mainly of sesquiterpenoids. The anti-inflammatory and hepatoprotective effects of CGEA have been reported, but the anti-fibrotic effects of CGEA via intestinal microbes and the "gut-liver axis" cycle have rarely been reported. In this study, we observed that CGEA not only directly attenuated inflammatory factor levels in inflamed mice, but also attenuated liver inflammation as well as liver fibrosis degeneration in rats with liver fibrosis caused by colitis. We observed in vitro that CGEA significantly promoted the growth of Bifidobacterium adolescentis. Similarly, fecal 16S rDNA sequencing of liver fibrosis rats showed that CGEA intervention significantly altered the composition of the intestinal microbiota of liver fibrosis rats. CGEA increased the abundance of intestinal microbiota, specifically, CGEA increased the ratio of Firmicutes to Bacteroidetes, CGEA could significantly increase the levels of Ruminococcus. In addition, CGEA intervention significantly protected intestinal mucosal tissues and improved intestinal barrier function in rats. Lactucin is the main sesquiterpenoid in CGEA, and HPLC results showed its content in CGEA was up to 6%. Lactucin has been reported to have significant anti-inflammatory activity, and in this study, we found that Lactucin decreased p38 kinases (p38), phosphorylation of the extracellular signal-regulated kinase (ERK) and protein kinase B (AKT) protein phosphorylation in lipopolysaccharide (LPS)-activated RAW264.7 cells, thereby reducing mRNA expression and protein expression of pro-inflammatory factors inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and inhibiting the release of inflammatory factors interleukin (IL)-6 and nitric oxide (NO), exerting anti-inflammatory effects. In summary, the prevention of liver fibrosis caused by intestinal inflammation by CGEA may be achieved by regulating the intestinal microbiota and restoring the intestinal barrier thereby improving the "gut-liver axis" circulation, reducing liver inflammation, and ultimately alleviating liver fibrosis. Notably, the direct anti-inflammatory effect of CGEA may be due to its content of Lactucin, which can exert anti-inflammatory effects by inhibiting the phosphorylation of Mitogen-activated protein kinase (MAPK) and Akt signaling pathways.

Characterization of soy protein isolate/Flammulina velutipes polysaccharide hydrogel and its immunostimulatory effects on RAW264.7 cells

Soy protein isolate (SPI) is a nutritional commercial product, while the poor solubility and gelling restricts its applications for functional foods. To surmount the challenge presented by this poor solubility, the gelling polysaccharide shows potential in ameliorating SPI. In this study, SPI/Flammulina velutipes polysaccharide (FVP) hydrogels were prepared under four mixing ratios (32:1, 20:1,15:1 and 10:1, w/w) at both pH6.5 and pH3.5, respectively. The stability of hydrogels and its immunostimulatory impact on RAW264.7 cells were assessed. Initial results revealed that water holding capacity increased when increasing the mixing ratios, likely to be the results of enhanced electrostatic interaction between SPI and FVP. The addition of FVP contributed to the improved swelling ratio and lowered the degradation ratio. Such structure feature was shown to be favorable for hydrogels to culture cells. More importantly, SPI/FVP hydrogels demonstrated no cytotoxic effect on cell metabolic activity. The culture of SPI/FVP hydrogels enhanced the immunostimulatory capacity in RAW264.7 cells by increasing phagocytosis and inducing the production of pro-inflammatory cytokines. The performances of the hydrogels made at pH3.5 were superior to those prepared at pH6.5. Our results suggested SPI/FVP hydrogels may provide application potential for the development of functional foods.

Isolation, purification and identification of immunologically active peptides from Hericium erinaceus

Biologically active peptides released by proteins are important in regulating immunity. The purpose of this study was to isolate and purify an immunologically active peptide from Hericium erinaceus (H. erinaceus) and to explore its effect on cytokine secretion and differentiation of macrophages. An active peptide with an amino acid sequence, Lys-Ser-Pro-Leu-Tyr (KSPLY) was obtained from H. erinaceus protein by ultrafiltration combined with multistage chromatography separation and identification technology. Subsequently, it was confirmed that the synthetic peptide KSPLY had a good immunomodulatory activity at a concentration of 100 μmol/L and could promote the secretion of NO, IL-1β, IL-6 and TNF-α by macrophages. The effects of KSPLY on M1 macrophages and M2 macrophages were also studied. Results showed that KSPLY inhibited the secretion of NO and IL-6 by M1 macrophages and promoted the tendency of M2 macrophages to transform to M1 macrophages. Therefore, it can be concluded that KSPLY is an effective immunomodulatory peptide that may be beneficial in cancer treatment and human health improvement.