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Fermentation enhances the amelioration effect of bee pollen on Caco-2 monolayer epithelial barrier dysfunction based on NF-?B-mediated MLCK-MLC signaling pathway
... First of all, the beneficial microorganisms and metabolites produced by the fermentation process help to maintain the intestinal microecological balance, inhibit the growth of harmful bacteria, and reduce the invasion of pathogenic bacteria to the intestine, thereby improving intestinal health [81]. Secondly, the bioactive substances in fermented feed, such as organic acids, enzymes, and peptides, can promote the growth and repair of intestinal mucosal cells, enhance intestinal barrier function, and prevent the penetration of harmful substances [82]. In addition, the bioactive ingredients rich in fermented feed can also regulate the function of the immune system, promote the generation and activity of immune cells, and improve the resistance and immunity of animals [83]. ...
Unconventional feed, which is abundant in China, contains anti-nutritional factors and toxins; however, these can be greatly reduced with microbial fermentation, thus improving the nutrient content of the feed, enhancing animal appetites, and ultimately significantly improving the intestinal health and growth performance of animals. When oxidative stress occurs, fermented feed can effectively reduce the damage caused by stress to the gastrointestinal tract, accelerate the removal of gastrointestinal abnormalities, improve the ability to resist intestinal stress, and ensure the efficient production of animals. This review introduces the application of unconventional fermented feed in animal production, and expounds upon the function of unconventional fermented feed in animals with oxidative stress symptoms, so as to provide a theoretical reference for the development and application of unconventional fermented feed in antioxidative stress reduction.
Bee-collected pollen is one of the most valuable natural products. However, the pollen cell walls limit the digestibility and release of nutrients to the human body. Solid-state lactic acid fermentation can be used to ease the release of bioactive compounds from the pollen cell. The aim of this research was to determine the impact of a solid-state lactic acid fermentation process on biologically active compound composition and antioxidant activity of bee-collected pollen from various European regions (Italy, Netherlands, Lithuania, Poland, Sweden, Denmark, Malta, Slovakia, and Spain). Spontaneous fermentation and fermentation using an L. rhamnosus culture were performed. The total content of phenolic compounds, total content of flavonoids, and radical (DPPH) scavenging activity were measured by spectrophotometric tests, while UPLC was employed for quantification of phenolic compounds. The determined fermentation positive effects included an increase of total phenolic content by 1.4–2.3 times, total flavonoid content by 1.1–1.6 times, and radical scavenging activity by 1.4–2.3 times. Naringenin (21.09–135.03 µg/g), quercetin (6.62–78.86 µg/g), luteolin (29.41–88.90 µg/g), and rutin (21.40–89.93 µg/g) were the most abundant flavonoids in all samples; however, their variation level was both geographical in origin and fermentation-type dependent. Fermentation increased the content of phenolic acids with high antioxidant potentials such as ellagic, ferulic and caffeic, while reduction of chlorogenic acid was determined.
Scorias spongiosa, as an edible fungus, has multiple health benefits. However, the effects of S. spongiosa on intestinal health are rarely explored. Hence, our study aims to elaborate on the influences of S. spongiosa polysaccharides (SSPs) on antioxidant, anti-inflammatory, and intestinal microflora in C57BL/6J mice. In the present study, 18 male mice were randomly distributed into three groups: (1) Control group (CON); (2) Low dose SSPs group (LSSP); (3) High dose SSPs group (HSSP). After 14-day administration, the jejunum and serum samples were collected for detection. The results showed that SSPs exert no effects on the growth performance of mice regardless of doses. Meanwhile, SSPs administration reduced the serum pro-inflammatory cytokines and elevated the anti-inflammatory cytokines. Moreover, the antioxidant capacity was elevated by SSPs administration, as evidenced by the increased contents of T-AOC, GSH-Px, and the decreased content of MDA. Mechanistically, the administration of SSPs enhanced the protein abundances of p-Nrf2, Keap1, and HO-1 in mice. The results of 16S rDNA demonstrated that the microbial community and composition were altered by SSPs administration. To summarize, SSPs benefit intestinal health in C57BL/6J mice via a mechanism that involves elevating antioxidant and anti-inflammatory activities and regulating intestinal microbiota.
Living species are continuously subjected to all extrinsic forms of reactive oxidants and others that are produced endogenously. There is extensive literature on the generation and effects of reactive oxygen species (ROS) in biological processes, both in terms of alteration and their role in cellular signaling and regulatory pathways. Cells produce ROS as a controlled physiological process, but increasing ROS becomes pathological and leads to oxidative stress and disease. The induction of oxidative stress is an imbalance between the production of radical species and the antioxidant defense systems, which can cause damage to cellular biomolecules, including lipids, proteins and DNA. Cellular and biochemical experiments have been complemented in various ways to explain the biological chemistry of ROS oxidants. However, it is often unclear how this translates into chemical reactions involving redox changes. This review addresses this question and includes a robust mechanistic explanation of the chemical reactions of ROS and oxidative stress.
We evaluated dendrobine for its potential effect on Inflammatory Bowel Disease (IBD) progression using the intestinal epithelial Caco-2/RAW264.7 macrophage co-culture cell model. The results showed that dendrobine maintained the tight junction (TJ) proteins in co-cultured Caco-2 cells, suggesting its protective effect on intestinal integrity. Moreover, the findings indicated that the dendrobine group downregulated levels of tumor necrosis factor-α (TNF-α), proinflammatory Interleukin (IL)-1β and IL-6, and inflammatory markers such as cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in co-cultured RAW264.7 cells. Additionally, dendrobine-mediated anti-inflammatory effects were observed based on the inhibition of LPS-induced proinflammatory mediators of nuclear factor kappa B (NF-κB)-related signaling. These results demonstrated the protective effect of dendrobine at effectively ameliorating intestinal barrier disruption and inhibiting activation of the NF-κB pathway in macrophages through the intestinal barrier.
We compared raw bee-collected pollen (Raw-BCP), spontaneously fermented BCP (Unstarted-BCP), and BCP fermented with selected microbial starters (Started-BCP) to deepen whether fermentation may favorably affect the nutrients bioaccessibility and functional features of BCP. Under in vitro gastrointestinal batches, the highest serum-availability of phenolic compounds was found in Started-BCP, highlighting the positive effect exerted by selected microbial starters. The same effect was not found in spontaneously fermented BCP. In colon adenocarcinoma cell line-2 (Caco-2) cells stressed by a pro-inflammatory stimulus, the treatment with Started-BCP halted the increase of pro-inflammatory mediator’s level. Started-BCP counteracted efficiently the deleterious effects of inflammatory stimuli on the integrity of the Caco-2 cells monolayer and its barrier function. Started-BCP successfully counteracted the H2O2-induced intracellular accumulation of reactive oxygen species (ROS) in Caco-2 cells. A protective role against lipopolysaccharide (LPS)-induced inflammation was exerted by Started-BCP in human keratinocytes. The same protective effects on Caco-2 and keratinocyte cell lines were negligible after treatments with Raw-BCP or Unstarted-BCP.
Oxidative stress occurs when there exists an imbalance between the generation and elimination of reactive oxygen species (ROS). As inevitable exposure to foreign substances and microbial pathogens, intestine is a key resource of ROS. Disproportionate generation and long-term exposure to ROS lead to various intestinal diseases, such as inflammatory bowel diseases (IBD), enteric infections, ischemic intestinal injury and colorectal cancers. Natural nutrients including vitamins, proteins, fats, minerals and phytochemicals provide numerous evidences that they can protect the health of intestine and alleviate the damage caused by oxidative stress, which can be developed as novel functional foods. This review summarized the recent research progress on the insights of the causes, mechanisms of intestinal oxidative stress and the health intervention effects of nutrients. This review has also given the prospects that the new discovered nutrients with health benefits might be developed as novel functional foods or possible nutraceutical agents.
Background:
The gut-liver axis is considered to play a critical role in the development and progression of nonalcoholic fatty liver disease (NAFLD). The integrity of the epithelial barrier is crucial to protect the liver against the invasion of microbial products from the gut, although its exact role in NAFLD onset and progression is not clear.
Methods:
We performed a systematic review and meta-analysis of studies that addressed the intestinal permeability (IP) in association with NAFLD presence or severity as defined by the presence of nonalcoholic steatohepatitis (NASH) and the degree of steatosis, hepatic inflammation or fibrosis. A total of 14 studies were eligible for inclusion.
Results:
Studies investigating IP in adult (n = 6) and paediatric (n = 8) NAFLD showed similar results. Thirteen of the included studies focussed on small IP, two studies on whole gut permeability and none on colonic permeability. In the pooled analysis, NAFLD patients showed an increased small intestinal permeability compared to healthy controls based on dual sugar tests (standardized mean difference 0.79, 95% CI 0.49-1.08) and serum zonulin levels (standardized mean difference 1.04 ng/mL, 95% CI 0.40-1.68). No clear difference in IP was observed between simple steatosis and NASH patients. Furthermore, whole gut and small intestinal permeability increased with the degree of hepatic steatosis in 4/4 studies, while no association with hepatic inflammation or fibrosis was observed.
Conclusion:
Based on the limited number of studies available, IP appears to be increased in NAFLD patients compared to healthy controls and is associated with the degree of hepatic steatosis.
This study was conducted to explore the protective potential of Fructooligosaccharides (FOS) against Enterotoxigenic Escherichia coli (ETEC)-induced inflammation and intestinal injury in weaned pigs. Twenty-four weaned pigs were randomly assigned...
The intestinal tract is the largest digestive organ in the human body. It is colonized by, and consistently exposed to, a myriad of microorganisms, including bifidobacteria, lactobacillus, Escherichia coli, enterococcus, clostridium perfringens, and pseudomonas. To protect the body from potential pathogens, the intestinal tract has evolved regional immune characteristics. These characteristics are defined by its unique structure, function, and microenvironment, which differ drastically from those of the common central and peripheral immune organs. The intestinal microenvironment created by the intestinal flora and its products significantly affects the immune function of the region. In turn, specific diseases regulate and influence the composition of the intestinal flora. A constant interplay occurs between the intestinal flora and immune system. Further, the intestinal microenvironment can be reconstructed by probiotic use or microbiota transplantation, functioning to recalibrate the immune homeostasis, while also contributing to the treatment or amelioration of diseases. In this review, we summarize the relationship between the intestinal flora and the occurrence and development of diseases as an in-turn effect on intestinal immunity. We also discuss improved immune function as it relates to non-specific and specific immunity. Further, we discuss the proliferation, differentiation and secretion of immune cells, within the intestinal region following remodeling of the microenvironment as a means to ameliorate and treat diseases. Finally, we suggest strategies for improved utilization of intestinal flora.
Cherry fruit has a high content in flavonoids. These are important diet components protecting against oxidative stress, inflammation, and endothelial dysfunction, which are all involved in the pathogenesis of atherosclerosis, which is the major cause of cardiovascular diseases (CVD). Since the seasonal availability of fresh fruit is limited, research has been focused on cherry extract (CE), which also possesses a high nutraceutical potential. Many clinical studies have demonstrated the nutraceutical efficacy of fresh cherries, but only a few studies on CE antioxidant and anti-inflammatory activities have been carried out. Here, the results concerning the antioxidant and anti-inflammatory activities of CE are reviewed. These were obtained by an in vitro model based on Human Umbilical Vein Endothelial Cells (HUVEC). To clarify the CE mechanism of action, cells were stressed to induce inflammation and endothelial dysfunction. Considering that antioxidants' polyphenol compounds are easily degraded in the gastrointestinal tract, recent strategies to reduce the degradation and improve the bioavailability of CE are also presented and discussed. In particular, we report on results obtained with nanoparticles (NP) based on chitosan derivatives (Ch-der), which improved the mucoadhesive properties of the chitosan polymers, as well as their positive charge, to favor high cellular interaction and polyphenols intestinal absorption, compared with a non-mucoadhesive negative surface charged poly(lactic-co-glycolic) acid NP. The advantages and safety of different nanosystems loaded with natural CE or other nutraceuticals are also discussed.
The study was conducted to investigate the effects of dietary stevioside (STE) supplementation on the lipopolysaccharide (LPS)-induced intestinal mucosal damage of broiler chickens. A total of 192 one-day-old male Ross 308 broiler chicks were randomly divided into four treatments: (1) basal diet (CON); (2) basal diet supplemented with 250 mg/kg stevioside (STE); (3) basal diet + LPS-challenge (LPS); (4) basal diet supplemented with 250 mg/kg stevioside + LPS-challenge (LPS + STE). LPS-challenged groups received an intraperitoneal injection of LPS at 17, 19 and 21 d, whereas the CON and STE groups received a saline injection. The results showed that dietary STE supplementation normalized LPS-induced changes in protein expression of p-NF-κB and p-IκBα, mRNA expression of inflammatory genes (TLR4, NF-κB, and IFN-γ), tight junction-related genes (CLDN2, OCLN, and ZO-1), and antioxidant genes (Nrf2 and HO-1). LPS-induced decreases in serum diamine oxidase (DAO) level, villus height-to-crypt depth ratio, apoptotic index, and protein expression of proliferating cell nuclear antigen (PCNA) were reversed with dietary STE supplementation. Additionally, STE supplementation ameliorated the redox damage by reducing malondialdehyde (MDA) content and increasing total antioxidant capacity (T-AOC) and antioxidant enzyme activity. In conclusion, dietary stevioside supplementation could alleviate LPS-induced intestinal mucosal damage through anti-inflammatory and antioxidant effects in broiler chickens.
Mechanistic target of rapamycin mTOR complex 1 (mTORC1) plays a key role in the integration of various environmental signals to regulate cell growth and metabolism. mTORC1 is recruited to the lysosome where it is activated by its interaction with GTP-bound Rheb GTPase. However, the regulatory mechanism of Rheb activity remains largely unknown. Here, we show that ubiquitination governs the nucleotide-bound status of Rheb. Lysosome-anchored E3 ligase RNF152 catalyzes Rheb ubiquitination and promotes its binding to the TSC complex. EGF enhances the deubiquitination of Rheb through AKT-dependent USP4 phosphorylation, leading to the release of Rheb from the TSC complex. Functionally, ubiquitination of Rheb is linked to mTORC1-mediated signaling and consequently regulates tumor growth. Thus, we propose a mechanistic model whereby Rheb–mediated mTORC1 activation is dictated by a dynamic opposing act between Rheb ubiquitination and deubiquitination that are catalyzed by RNF152 and USP4 respectively.
Background: In people with acute pancreatitis, it is unclear what the role should be for medical treatment as an addition to supportive care such as fluid and electrolyte balance and organ support in people with organ failure. Objectives: To assess the effects of different pharmacological interventions in people with acute pancreatitis. Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL, 2016, Issue 9), MEDLINE, Embase, Science Citation Index Expanded, and trial registers to October 2016 to identify randomised controlled trials (RCTs). We also searched the references of included trials to identify further trials. Selection criteria We considered only RCTs performed in people with acute pancreatitis, irrespective of aetiology, severity, presence of infection, language, blinding, or publication status for inclusion in the review. Data collection and analysis: Two review authors independently identified trials and extracted data. We did not perform a network meta-analysis as planned because of the lack of information on potential effect modifiers and differences of type of participants included in the different comparisons, when information was available. We calculated the odds ratio (OR) with 95% confidence intervals (CIs) for the binary outcomes and rate ratios with 95% CIs for count outcomes using a fixed-effect model and random-effects model. Main results: We included 84 RCTs with 8234 participants in this review. Six trials (N = 658) did not report any of the outcomes of interest for this review. The remaining 78 trials excluded 210 participants after randomisation. Thus, a total of 7366 participants in 78 trials contributed to one or more outcomes for this review. The treatments assessed in these 78 trials included antibiotics, antioxidants, aprotinin, atropine, calcitonin, cimetidine, EDTA (ethylenediaminetetraacetic acid), gabexate, glucagon, iniprol, lexipafant, NSAIDs (non-steroidal anti-inflammatory drugs), octreotide, oxyphenonium, probiotics, activated protein C, somatostatin, somatostatin plus omeprazole, somatostatin plus ulinastatin, thymosin, ulinastatin, and inactive control. Apart from the comparison of antibiotics versus control, which included a large proportion of participants with necrotising pancreatitis, the remaining comparisons had only a small proportion of patients with this condition. Most trials included either only participants with severe acute pancreatitis or included a mixture of participants with mild acute pancreatitis and severe acute pancreatitis (75 trials). Overall, the risk of bias in trials was unclear or high for all but one of the trials. Source of funding: seven trials were not funded or funded by agencies without vested interest in results. Pharmaceutical companies partially or fully funded 21 trials. The source of funding was not available from the remaining trials. Since we considered short-term mortality as the most important outcome, we presented only these results in detail in the abstract. Sixty-seven studies including 6638 participants reported short-term mortality. There was no evidence of any differences in short-term mortality in any of the comparisons (very low-quality evidence). With regards to other primary outcomes, serious adverse events (number) were lower than control in participants taking lexipafant (rate ratio 0.67, 95% CI 0.46 to 0.96; N = 290; 1 study; very low-quality evidence), octreotide (rate ratio 0.74, 95% CI 0.60 to 0.89; N = 770; 5 studies; very low-quality evidence), somatostatin plus omeprazole (rate ratio 0.36, 95% CI 0.19 to 0.70; N = 140; 1 study; low-quality evidence), and somatostatin plus ulinastatin (rate ratio 0.30, 95% CI 0.15 to 0.60; N = 122; 1 study; low-quality evidence). The proportion of people with organ failure was lower in octreotide than control (OR 0.51, 95% CI 0.27 to 0.97; N = 430; 3 studies; very low-quality evidence). The proportion of people with sepsis was lower in lexipafant than control (OR 0.26, 95% CI 0.08 to 0.83; N = 290; 1 study; very low-quality evidence). There was no evidence of differences in any of the remaining comparisons in these outcomes or for any of the remaining primary outcomes (the proportion of participants experiencing at least one serious adverse event and the occurrence of infected pancreatic necrosis). None of the trials reported heath-related quality of life. Authors' conclusions: Very low-quality evidence suggests that none of the pharmacological treatments studied decrease short-term mortality in people with acute pancreatitis. However, the confidence intervals were wide and consistent with an increase or decrease in short-term mortality due to the interventions. We did not find consistent clinical benefits with any intervention. Because of the limitations in the prognostic scoring systems and because damage to organs may occur in acute pancreatitis before they are clinically manifest, future trials should consider including pancreatitis of all severity but power the study to measure the differences in the subgroup of people with severe acute pancreatitis. It may be difficult to power the studies based on mortality. Future trials in participants with acute pancreatitis should consider other outcomes such as complications or health-related quality of life as primary outcomes. Such trials should include health-related quality of life, costs, and return to work as outcomes and should follow patients for at least three months (preferably for at least one year).
Body and organ surfaces in multicellular organisms are covered with a sheet of epithelial cells. The tight junction (TJ) is an adhesive structure that seals the gap between epithelial cells and functions as a selective barrier to prevent the entry of antigens and pathogenic microbes from the extracellular environment. Several transmembrane proteins that constitute the TJ (claudin, occludin, tricellulin, and angulin) have been identified. As over-expression of these proteins does not enlarge TJs or enhance epithelial barrier function, it remains unclear how TJ membrane proteins are regulated to modulate the amount of TJ and the strength of the epithelial barrier. In this review, we discuss the post-translational modifications of TJ membrane proteins and their physiological significance from the viewpoint of the dynamic regulation of the epithelial barrier.
Chronic inflammation disrupts intestinal barrier function and may contribute to the pathology of obesity and other diseases. The goal of this study was to determine the mechanism by which yogurt improves intestinal barrier function. Caco-2 cells were differentiated on Transwell inserts and used as a model of intestinal barrier permeability. Transepithelial electrical resistance (TEER) and flux of 4 kDa fluorescein isothiocyanate-dextran (FD) and lucifer yellow (LY) were used as indicators of monolayer integrity and paracellular permeability. Immunofluorescence microscopy and real time quantitative polymerase chain were used to assess the localization and expression of tight junction proteins known to regulate intestinal permeability. Differentiated cells were treated with a vehicle control (C), inflammatory stimulus (I) (interleukin-1β, tumor necrosis factor-α, interferon-γ, and lipopolysaccharide), or I and 0.03 g mL(-1) yogurt (IY). After 48 h, I reduced Caco-2 TEER by 46%, while IY reduced TEER by only 27% (P < 0.0001). FD and LY flux reflected TEER measurements, with IY having significantly lower permeability than I (P < 0.05). Yogurt also improved localization of occludin and zona occludens protein 1 (ZO-1) at tight junctions of differentiated Caco-2 cells. IY increased Caco-2 claudin-1, ZO-1, and occludin mRNA relative to I (P < 0.05). In a simulated digestion, the barrier-improving bioactivity of yogurt was maintained through the gastric phase, but was reduced to the level of I after intestinal digestion (P < 0.05). Therefore, yogurt improved inflammation-disrupted intestinal barrier function in a Caco-2 model by increasing tight junctions, but the beneficial effect on barrier function was reduced at latter stages of digestion.
Background
This study examined the effect of kaempferol on uterine fibroids in vitro and the underlying mechanism, and investigated the potential of kaempferol as a clinical drug for the treatment of uterine fibroids.
Material/Methods
Uterine fibroid tissue and surrounding smooth muscle tissue were collected for primary culture. Different concentrations of kaempferol (12 μM, 24 μM, and 48 μM) were used to treat the cells for 24, 48, and 72 hours. Ethanol was used in the control group. A CCK-8 colorimetric assay was used to detect cell proliferation. Real-time PCR and immunoblot were used to detect estrogen receptor (ER), insulin-like growth factor-1 (IGF-1), and vascular endothelial growth factor (VEGF) levels in mRNA and protein.
Results
The differences in proliferation at different time points and concentrations of kaempferol were statistically significant. The inhibitory effect of kaempferol on mRNA levels of ER and IGF, and protein levels of ER, VEGF, and IGF-1 were positively correlated with kaempferol concentration. Changes in kaempferol concentration showed no effect on VEGF mRNA expression. Treatment with kaempferol significantly lowered myocardin levels in uterine fibroid tissue compared to normal uterine smooth muscle (P<0.05).
Conclusions
Kaempferol might be used for clinical treatment of uterine fibroids due to its inhibitory effect on the proliferation of uterine fibroids cells.
The intestinal barrier protects the host from harmful substances. This paper investigated two polysaccharides extracted from the Hericium erinaceus before and after fermentation (HEP and FHEP). The effects of two polysaccharides on the intestinal barrier were investigated in cell and mice models. The results showed that polysaccharides had a protective effect against acrylamide-induced injury in IEC-6 cell. Compared with HEP, FHEP significantly increased TEER and paracellular permeability (P < 0.05). Both polysaccharides the expression of alter tight junction (TJ) and mucin (MUC) as observed in cell Western Bolt (WB). Polysaccharides also enhance the intestinal barrier function in mice by improving cyclophosphamide induced cytokines level, TJ and MUC expression, and gut microbiota. The results showed that FHEP significantly increased IgA, IgG, and IgM levels while decreasing TNF-, IL-1, and IL-6 levels (P < 0.05). The immunohistochemical results showed that both polysaccharides significantly increased the expression of occludin, ZO-1, ZO-2, claudin-3, claudin-4, MUC2 and decreased claudin-2. In parallel, polysaccharides could alter the composition of the gut microbiota, indicating that increased in Bacteriodetes, Firmicutes and decreased in Klebsiella and Shigella. This work provides important views on the protective effect of fermented polysaccharides on the intestinal barrier, and provides a potential mechanism for the beneficial health properties of these biomacromolecules.
As a common food processing technology, microbial fermentation is becoming increasingly popular to promote the bioactivity of materials. This study aims to enhance rape bee pollen bioactivity through fermentation and trace the potential components associated with its bioactivity. The antioxidant and anti-inflammatory activities of unfermented bee pollen and fermented bee pollen were evaluated, and their correlation with differential metabolites was analyzed. The results indicated that fermentation significantly (p < 0.05) improved the antioxidant (>2.3-fold) and anti-inflammatory (>1.36-fold) activities of bee pollen, and increased the contents of total phenolics and flavonoids by 1.99 and 1.53 folds. Moreover, the correlation analysis results indicated that 15 components, including three phenolamides, one flavonoid aglycone, seven fatty acids, three amino acids and one ketone compound, were positively correlated with bee pollen antioxidant and anti-inflammatory activities. These results suggest that fermentation is a promising approach to increase the bioactivity of bee pollen.
The intestinal barrier dysfunction associated with chronic inflammation is a major health concern. This work aimed to investigate the protective effect and molecular mechanism of Senegalia macrostachya seed polysaccharide fraction (SMSP2) on inflammation-induced barrier dysfunction using Caco-2 cells and RAW264.7 macrophage co-culture model. The results showed that LPS stimulation of the basolateral RAW264.7 compromised the integrity of the apical differentiated Caco-2 cells monolayer, resulting in decreased transepithelial electrical resistance (TER) and increased inflammatory markers. SMSP2 apical treatment maintained a higher TER value and reduced the epithelial permeability to lucifer yellow (LY) dye. In addition, the SMSP2 group showed a significant decrease in the mRNA level of inflammatory factors such as inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), interleukin (IL)-8, and tumor necrosis factor-α (TNF-α) in the Caco-2 monolayer compared to the LPS group. Moreover, SMSP2 increased the expression of the tight junctions (TJ) zonula occludens (ZO-1), occludin, and claudin-1 at the mRNA and protein levels. Furthermore, the immunofluorescence assay showed that SMSP2 ameliorated the overall distribution of the TJ proteins in the Caco-2 monolayer. SMSP2 application also resulted in the downregulation of the nuclear factor kappa-B (NF-κB) phosphorylation and the myosin light chain kinase (MLCK) expression, which implies that SMSP2 preserved the monolayer integrity from the inflammation-induced barrier disruption through the inhibition of the NF-kB-mediated MLCK signaling pathway activation. Senegalia macrostachya seeds could therefore be a promising functional food that could be used to improve intestinal barrier function.
Proanthocyanidins have been shown to inhibit the signaling pathways related to oxidative stress and inflammation, also improved cell membrane integrity. The effect of peanut skin proanthocyanidins (PSPc) on CD remains unknown. In this paper, the effect and mechanism of PSPc on glial protein-induced Caco-2 cytotoxicity were studied. The results showed that PSPc may inhibit oxidative stress in DPG-induced CD model in vitro by regulating SIRT1/NRF2 pathway. By regulating SIRT1 and IκB signaling pathways, inhibit the phosphorylation of NF-κB and the deacetylation of NF-κB, inhibit inflammatory response, reduce release of inflammatory cytokines (IL-1β, IL-6, TNF-α), the cell survival rate was and the expression of TGM2 were improved, avoiding the damage of cell monolayer model. This experiment proved the prominent effect of PSPc on CD intervention. Studying the mechanism of PSPc in the treatment of CD injury will contribute to explore new therapies for CD which will be of great significance to supplement or replace gluten-free diets.
Intestinal epithelial barrier dysfunction can cause several intestinal diseases. Flavonoids have been shown to be beneficial to the intestinal epithelial barrier function. However, the effects of taxifolin (TAX), a naturally occurring flavonoid, on the intestinal epithelial barrier function are unclear. Thus, the aims of this study were to investigate the protective effect and potential mechanism of TAX against lipopolysaccharide (LPS)-induced intestinal epithelial barrier dysfunction in a Caco-2 cell monolayer model. Our results showed that TAX increased the transepithelial electrical resistance (TEER) and decreased the fluorescein isothiocyanate (FITC)-dextran (4 kDa) flux in the damaged intestinal epithelial barrier. Meanwhile, TAX inhibited an LPS-induced decrease in mRNA and protein expression of tight junction (TJ) proteins (claudin-1, zonula occludens [ZO]-1, and occludin), and ameliorating the continuous distribution pattern disrupted of TJs. These results suggested that TAX ameliorated intestinal epithelial barrier dysfunction. Regarding the underlying mechanism, TAX reduced the LPS-induced secretion of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in Caco-2 cell monolayers. In addition, TAX suppressed the phosphorylation of nuclear factor kappa-B (NF-κB), inhibitor protein of NF-κBα (IκBα), and myosin light chain (MLC), and downregulated the expression of myosin light chain kinase (MLCK) in LPS-treated Caco-2 cells. In summary, TAX can maintain TJ proteins by inhibiting the NF-κB/MLCK pathway and pro-inflammatory factor secretion to ameliorate LPS-induced intestinal epithelial barrier dysfunction. Thus, TAX is a promising candidate agent for use in functional food to ameliorate intestinal barrier dysfunction.
The intestinal barrier protects the host against gut microbes, food antigens, and toxins present in the gastrointestinal tract. However, gut barrier integrity can be affected by intrinsic and extrinsic factors, including genetic predisposition, the Western diet, antibiotics, alcohol, circadian rhythm disruption, psychological stress, and aging. Chronic disruption of the gut barrier can lead to translocation of microbial components into the body, producing systemic, low-grade inflammation. While the association between gut barrier integrity and inflammation in intestinal diseases is well established, we review here recent studies indicating that the gut barrier and microbiota dysbiosis may contribute to the development of metabolic, autoimmune, and aging-related disorders. Emerging interventions to improve gut barrier integrity and microbiota composition are also described.
Microbial fermentation can break the bee pollen wall. However, the global profiling of bee pollen metabolites under fermentation remains unclear. This study aims to comprehensively elucidate the changes in the composition of bee pollen after microbial fermentation. Ultra-performance liquid chromatography-electron spray ionization-mass spectrometry (UPLC-ESI-MS) based on widely targeted metabolomics analysis was used to compare the chemical composition of unfermented bee pollen (UBP) and fermented bee pollen (FBP). Among the 890 metabolites detected, a total of 668 differential metabolites (classified into 17 categories) were identified between UBP and FBP. Fermentation significantly increased the contents of primary metabolites such as 74 amino acids and derivatives, 42 polyunsaturated fatty acids and 66 organic acids, as well as some secondary metabolites such as 38 phenolic acids, 80 flavone aglycones and 22 phenolamides. The results indicate that fermentation is a promising strategy to improve the nutritional value of bee pollen.
Inflammatory bowel disease (IBD) is a long-term chronic disease, about 20% of IBD patients deteriorate to colorectal cancer. Currently, there is no radical cure for IBD. Natural plant polysaccharides (NPP) have low toxic and side effects, which have immune and prebiotic activities and possesses positive effect on alleviating IBD. In this review, we will focus on the alleviating effect of NPP on IBD in vitro and in vivo from three aspects: regulating intestinal flora imbalance, repairing intestinal barrier injury and improving immunity. The relationship between the chemical structure of natural plant polysaccharides and the therapeutic effect of IBD are highlighted. Finally, the synergistic role of NPP as a carrier of drugs or active molecules to reduce side effects and enhance targeting function are discussed, especially pectic polysaccharides. Broadly, this review provides a valuable reference for NPP to be developed as functional food or health products to alleviate IBD.
BACKGROUND
S AND AIMS: Increased permeability is implicated in the pathogenesis of intestinal disease. In vitro and in vivo studies have linked downregulation of the scaffolding protein ZO-1, encoded by the TJP1 gene, to increased tight junction permeability. This has not, however, been tested in vivo. Here, we assessed the contributions of ZO-1 to epithelial barrier function and mucosal homeostasis.
METHODS
Public GEO data sets and biopsies from inflammatory bowel disease (IBD) patients and healthy controls were analyzed. Tjp1f/f; vil-CreTg mice with intestinal epithelial-specific ZO-1 knockout (ZO-1KO.IEC) mice and Tjp1f/f mice littermates, without Cre expression, were studied using chemical and immune-mediated models of disease as well as colonic stem cell cultures.
RESULTS
ZO-1 transcript and protein expression were reduced in IBD patient biopsies. Despite mildly increased intestinal permeability, ZO-1KO.IEC mice were healthy and did not develop spontaneous disease. ZO-1KO.IEC mice were hypersensitive to mucosal insults and displayed defective repair. Further, ZO-1-deficient colonic epithelia failed to upregulate proliferation in response to damage in vivo or Wnt signaling in vitro. ZO-1 associated with centrioles in interphase cells and mitotic spindle poles during division. In the absence of ZO-1, mitotic spindles failed to correctly orient, resulting in mitotic catastrophe and abortive proliferation. ZO-1 is, therefore, critical for upregulation of epithelial proliferation and successful completion of mitosis.
CONCLUSION
ZO-1 makes critical, tight junction-independent contributions to Wnt signaling and mitotic spindle orientation. As a result, ZO-1 is essential for mucosal repair. We speculate that ZO-1 downregulation may be one cause of ineffective mucosal healing in IBD patients.
The intestinal barrier is vital for preventing inflammatory bowel disease (IBD). This study aimed to investigate the potential mechanism behind the protective effects of B. dentium N8 on the intestinal barrier using the lipopolysaccharide (LPS)-induced Caco-2 cells model. Our probiotic validation results showed that B. dentium N8 had a higher adhesion ability and a more substantial inhibition effect on Escherichia coli ATCC 25922 adhesion to HT-29 cells. Regarding the epithelial integrity, B. dentium N8 significantly increased the trans-epithelial electrical resistance (TEER) value and decreased the paracellular permeability of Caco-2 cells stimulated by lipopolysaccharide (LPS). In addition, B. dentium N8 significantly increased ZO-1, occludin, and claudin-1 mRNA expression. B. dentium N8 downregulated the mRNA expression level of TLR4 and pro-inflammatory cytokines (TNF-α, IL-1β, IL-6). Furthermore, B. dentium N8 had a better protective effect on the intestinal barrier than that of E7. Comparative genomics of B. dentium N8 and E7 showed B. dentium N8 had the specific genes encoding for adhesion ability and immune system regulation. The findings provide the theoretical basis for B. dentium N8 possessing a protective effect on the intestinal barrier, which indicate that it could be used as a novel therapy for IBD.
A simple and reliable in vitro model of the infant intestinal barrier is needed to study nutrient absorption and drug permeability specifically for this life stage. This study investigated the treatment of 20 day old differentiated Caco-2 monolayers with sodium butyrate at various concentrations (0-250 mM). Monolayer integrity, cytotoxicity, permeability and inflammatory response were tracked. An intestinal barrier model, with infant gut characteristics, was developed based on the treatment of mature monolayers with 125 mM sodium butyrate for 24 h. Such treatment was not cytotoxic but caused a stable transepithelial electrical resistance value of 408 ± 52 Ω cm2. The ratio of lactulose to mannitol transport across the intestinal barrier increased 1.79-fold. Redistribution of the tight junction proteins, occludin and ZO-1, in response to sodium butyrate treatment was visualized with immunofluorescence. Levels of the cytokines, TNF-α and IL-6, although modestly increased did not indicate an inflammatory response by Caco-2 to sodium butyrate. This intestinal barrier demonstrated physiologically relevant transport rates for dairy protein of 0.01-0.06%, suggesting it may be used to track permeability of proteins in infant nutritional products.
Tartary buckwheat dough (120 g) was used to produce steamed tartary buckwheat bread (STB). Alterations in antioxidant capacity and α-glucosidase inhibitory activity levels, and the concentrations of various flavonoid compounds, were investigated after each processing stage. It was identified that aglycone (quercetin and kaempferol) levels were increased after dough formation and fermentation stages. These stages were also associated with higher antioxidant capacity and α-glucosidase inhibitory activity. After steaming, flavonoid compound and antioxidant activity levels were slightly decreased in comparison to those observed after dough formation and fermentation steps, although they were higher than in raw flour.
To clarify the anti-diabetic potential of individual flavonoid compounds, the antioxidant and α-glucosidase inhibitory activities of four distinct flavonoids were investigated. The results of the present study revealed that aglycones have more potent anti-diabetic effects than their corresponding glycosides, which may explain the change in antioxidant and α-glucosidase inhibitory activities of samples taken after the different processing stages. Correlation analysis also indicated that flavonoids’ being in their aglycone form was positively associated with higher antioxidant and α-glucosidase inhibitory activities. Overall, these data suggest that deglycosylation of flavonoids, which occurs during the preparation of STB, contributes to higher hypoglycemic potential in tartary buckwheat bread products.
Ethnopharmacological relevance
Phaseaoli pericarpium (bean pods) is a pharmacopeial plant material traditionally used as a diuretic and antidiabetic agents. Diuretic activity of pod extracts was reported first in 1608. Since then Phaseoli pericarpium tea figures in many textbooks as medicinal plant material used by patients.
Aim of the study
Despite the traditional use of extracts from Phaseolium vulgaris pericarp, limited information is available on bioactivity, chemical composition, and bioavailability of such preparations. The following study aimed to investigate the phytochemical composition, the in vitro permeability of selected extract’s constituents over the Caco-2 permeation system, and potential antivirulence activity against uropathogenic Escherichia coli of a hydroalcoholic Phaseoli pericarpium extract (PPX) in vitro to support its traditional use as a remedy used in urinary tract infections.
Material and methods
The chemical composition of the extract PPX [ethanol:water 7:3(v/v)] investigated by using UHPLC-DAD-MSⁿ and subsequent dereplication. The permeability of compounds present in PPX was evaluated using the Caco-2 monolayer permeation system. The influence of PPX on uropathogenic E.coli (UPEC) strain NU14 proliferation and against the bacterial adhesion to T24 epithelial cells was determined by turbidimetric assay and flow cytometry, respectively. The influence of the extract on the mitochondrial activity of T24 host cells was monitored by MTT assay.
Results
LC-MSⁿ investigation and dereplication, indicated PPX extract to be dominated by a variety of flavonoids, with rutin as a major compound, and soyasaponin derivatives. Rutin, selected soyasaponins and fatty acids were shown to permeate the Caco-2 monolayer system, indicating potential bioavailability following oral intake. The extract did not influence the viability of T24 cells after 1.5h incubation at 2 mg/mL and UPEC. PPX significantly reduced the bacterial adhesion of UPEC to human bladder cells in a concentration-dependent manner (0.5 to 2 mg/mL). Detailed investigations by different incubation protocols indicated that PPX seems to interact with T24 cells, which subsequently leads to reduced recognition and adhesion of UPEC to the host cell membrane.
Conclusions
PPX is characterised by the presence of flavonoids (e.g. rutin) and saponins, from which selected compounds might be bioavailable after oral application, as indicated by the Caco-2 permeation experiments. Rutin and some saponins can be considered as potentially bioavailable after the oral intake. The concentration-dependent inhibition of bacterial adhesion of UPEC to T24 cells justifies the traditional use of Phaseoli pericarpium in the prevention and treatment of urinary tract infections.
The intestine is an important digestive organ of the human body, and its barrier is the guardian of the body from the external environment. The impairment of the intestinal barrier is believed to be an important determinant in various foodborne diseases. Food hazards can lead to the occurrence of many foodborne diseases represented by inflammation. Therefore, understanding the mechanisms of the impact of the food hazards on intestinal barriers is essential for promoting human health. This review examined the relationship between food hazards and the intestinal barrier in three aspects: apoptosis, imbalance of gut microbiota, and pro-inflammatory cytokines. The mechanism of dysfunctional gut microbiota caused by food hazards was also discussed. This review discusses the interaction among food hazards, intestinal barrier, and foodborne diseases and, thus, offers a new thought to deal with foodborne disease.
Background
Food-intestine interaction study has always been a hot topic in food science and nutrition due to diverse physiological functions of intestine. Compared to expensive animal models with limited screening capabilities, the simple, reliable and highly reproducible intestinal cell models are widely used in food-intestine interaction study. There are many functional cell models used to simulate the intestine in vitro, among which the Caco-2 cell model is one of the most widely used and classical models. Recently years, the differentiated Caco-2 cell model has been greatly developed due to the development of various technologies, which not only overcomes the limitations of the traditional model, but also further broadens its application.
Scope and approach
This review aims to overview the current applications of the differentiated Caco-2 cell model as a specialized model of intestinal cells in vitro, as well as new approaches solving the existing challenges of utilization, which can guide its future trends in interaction between food factors and the intestine.
Key findings and conclusions: With high flexibility, high repeatability and low cost, the differentiated Caco-2 cell model has been applied to a variety of intestinal studies including intestinal absorption, intestinal transport, intestinal metabolism, intestinal barrier, intestinal immunity and intestinal adhesion. Furthermore, future study should break limitations of traditional models with the help of automation, biochemistry, molecular biology and cells co-culture, so as to make it more closer to the internal environment without sacrificing its simplicity and reliability, and more suitable for cost-effective large-scale analysis of food-intestine interaction.
To investigate the effects of formononetin on rats with gastric ulcer and further to explore its possible mechanism. Rats were randomly divided into sham operation group (Sham), model group (Model), omeprazole control group (Omeprazole) and formononetin in different dose groups (FOR-L, FOR-M, FOR-H). Rats model with gastric ulcer were established by 100% glacial acetic acid. Hematoxylin-eosin (H&E) staining was used to observe the pathological morphology of gastric mucosa. Immunohistochemistry and enzyme-linked immunosorbent assay (ELISA) were used to detect the level of inflammatory and angiogenesis related factors. The expressions of nuclear factor kappa-B (NF-κB) signaling pathway-related proteins were detected by western blot. Formononetin and omeprazole could ameliorate the pathological morphology of gastric mucosa in gastric ulcer rats. Compared with Model group, the levels of tumor necrosis factor (TNF)-α, Interleukin (IL)-1β, IL-6, myeloperoxidase (MPO), human endothelin (ET)-1 and p-P65 protein in formononetin treatment and omeprazole groups were significantly decreased (p < 0.05). Moreover, formononetin could increase the content of vascular endothelial growth factor (VEGF), nitric oxide (NO) and the levels of CD34, tight junction proteins (ZO-1 and occludin) and p-IκBα in a dose-dependent manner. Formononetin can ameliorate gastric ulcer in rats by inhibiting inflammation and promoting gastric mucosal angiogenesis, and its mechanism maybe related to NF-κB signaling pathway.
Ethnopharmacological relevance:
Lizhong Decoction (LZD) is a classical prescription firstly recorded in "Shanghan Lun". It has been used to clinically treat ulcerative colitis (UC) for thousands of years. However, its mechanism is not clear up to now.
Aim of the study:
The goal of this study was to assess the amelioration of LZD on dextran sodium sulfate (DSS)-induced colitis in mice and further clarify its mechanism.
Materials and methods:
The ulcerative colitis model induced by DSS was successfully established and applied to evaluate the intervention effect after oral administration of LZD. Furthermore, the expression of key targets in inflammatory signaling pathways and intestinal tight junction proteins were investigated by enzyme-linked immunosorbent assay (ELISA) and quantitative real time polymerase chain reaction (qPCR) analysis.
Results:
The results showed that all doses of LZD could notably improve DSS-induced colon lesions, reduce histological scores, prolong colon length and increase body weight. Colonic inflammation in UC mice was significantly alleviated by inhibiting the activities of myeloperoxidase (MPO) and superoxide dismutase (SOD), reducing the yield of nitric oxide (NO) and inflammatory cytokines such as interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6), and along with promoting the production of anti-inflammatory cytokines such as interleukin-4 (IL-4) and interleukin-10 (IL-10) after LZD treatment. Furthermore, LZD remarkably down-regulated the level of toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) mRNA and up-regulated the expression of tight junction proteins (zonula occluden-1, occludin and claudin-1) in UC mice.
Conclusion:
In summary, this study indicated that LZD could notably improve UC symptoms by suppressing inflammation and ameliorating gut barrier, which provided scientific basis for its clinical application in the future.
The aqueous extract of Passiflora edulis leaves is rich in bioactive polyphenolics, with antioxidant and anti-inflammatory properties. In this study, the recovery of barrier dysfunction and the anti-inflammatory effect of P. edulis leaf aqueous extract (PELE) were evaluated using a Caco-2 monolayer model challenged with IL-1β and LPS. After inflammatory stimuli, it was observed a 28% reduction in transepithelial electrical resistance (TER) and 78% increase of LY permeability. After 48-h treatment with PELE (10 mg mL⁻¹), the monolayer showed 35% increase in TER after inflammatory decreases, and 67% lower LY paracellular permeability, showing a recovery of the monolayer integrity. The treatment also suppressed IL-8 production in 65%. Our results suggest that PELE is a potent source of antioxidants that may promote a protective effect by repairing the intestinal epithelial integrity.
Bee pollen (BP) shows profound gut-protecting potentials. BP lipids (BPL) mainly composed by phospholipids and polyunsaturated fatty acids might be one of the important contributors, while how BPL exerts gut-protecting effects and transports through intestinal cell monolayers need to be investigated. Here, we exploited a strategy that combining an UPLC-Q-Exactive orbitrap/MS-based lipidomics approach with a human intestinal cell (Caco-2) monolayer transport model, to determine the transepithelial transportation of BPL from Camellia sinensis L. (BPL-Cs), in pathological conditions. The results showed that BPL-Cs protected Caco-2 cells against dextran sulfate sodium (DSS)-induced intestinal barrier dysfunction by improving cell viability, maintaining membrane integrity, increasing tight junctions (ZO-1 and Claudin-1), and eliciting the expressions of antioxidative-related genes (NQO1, Nrf2, Txnrd1, and GSTA1). Lipidomics analysis revealed that DSS suppressed the transport and uptake of most of BPL-Cs including glycerophospholipids, sphingomyelins, and glycosylsphingolipids. Pretreatment with BPL-Cs significantly regulated glycerophospholipid and sphingolipid metabolisms, potentially involved in building permeability barriers, and alleviating intestinal oxidative stress. Finally, eight classes of lipids were identified as the potential biomarkers for evaluating DSS-induced Caco-2 cell dysfunctions and BPL-intervened modulation. These findings shed a light on the development of BPL as gastrointestinal protective food supplements in the future.
Inflammatory bowel disease (IBD) is a chronic inflammatory disease of intestinal mucosa and submucosa, characterized by the disruption of intestinal epithelial barrier, increased production of inflammatory mediators and excessive tissue injury. Intestinal epithelial cells, as well as microvascular endothelial cells, play important roles in IBD. To study the potential effects of kaempferol in IBD progress, we established a novel epithelial-endothelial cells co-culture model to investigate the intestinal inflammation and barrier function. Data demonstrated an obvious increased transepithelial electrical resistance (TEER) (1222 ± 60.40 Ωcm2 vs 1371 ± 38.77 Ωcm2), decreased flux of FITC(180.8 ± 20.06 μg/ml vs 136.7 ± 14.78 μg/ml) and up-regulated occludin and claudin-2 expression in Caco-2 that was specifically cocultured with endothelial cells. Meanwhile, 80 μM kaempferol alleviated the drop of TEER, the increase of FITC flux and the overexpression of Interleukin-8 (IL-8) induced by 1 μg/mL lipopolysaccharide (LPS). Additionally, kaempferol also ameliorated LPS-induced decrease of protein expression of zonula occludens-1 (ZO-1), occludin and claudin-2, together with the inhibited protein expressions of phosphorylation level of NF-κB and I-κB induced by LPS. Our results suggest that kaempferol alleviates the IL-8 secretion and barrier dysfunction of Caco-2 monolayer in LPS-induced epithelial-endothelial co-culture model via inhibiting NF-κB signaling pathway activation.
The intestinal epithelial layer forms a barrier through cell-cell tight junctions and breaking or even slightly disrupting this barrier can lead to serious pathological consequences, including infection and inflammation. Various amino acids have been shown to improve the intestinal tract, but the effect of tryptophan on the intestinal barrier has been controversial. Here, an in vitro Caco-2 cell model was built to investigate the protective and reparative effects of different concentrations of dietary l-Tryptophan (l-Trp) on lipopolysaccharide (LPS)-induced intestinal tight junction injury. Lower concentrations (40 μM) of dietary l-Trp protected and repaired the integrity and permeability injury of the intestinal tight junction induced by LPS, while high concentrations (80 μM) may not have a positive effect. LPS-induced injury led to increased (P < 0.05) mRNA expression of Nuclear factor-kappa B (NFκB) and Myosin light-chain kinase (MLCK), and decreased (P < 0.05) the mRNA expression of extracellular regulated protein kinase 1/2 (ERK1/2) and Mitogen-activated protein (MAP), and the treatment of dietary l-Trp alleviated those regulations in different concentrations, which suggests that dietary l-Trp may attenuate LPS-induced injury to tight junctions via inhibiting the NFκB-MLCK signaling pathway and activating the ERK1/2-MAP signaling pathway. And the mRNA and protein expressions of claudin-1, occludin and ZO-1 in LPS-induced injury were all down-regulated to varying degrees, and dietary l-Trp weakened the down-regulation of claudin-1 (P < 0.05) with no significant regulation of the protein expression of occludin and ZO-1 (P > 0.05).
Recent experimental data and clinical, genetic, and transcriptome evidence from patients converge to suggest a key role of interleukin-1β (IL-1β) in the pathogenesis of Kawasaki disease (KD). However, the molecular mechanisms involved in the development of cardiovascular lesions during KD vasculitis are still unknown. Here, we investigated intestinal barrier function in KD vasculitis and observed evidence of intestinal permeability and elevated circulating secretory immunoglobulin A (sIgA) in KD patients, as well as elevated sIgA and IgA deposition in vascular tissues in a mouse model of KD vasculitis. Targeting intestinal permeability corrected gut permeability, prevented IgA deposition and ameliorated cardiovascular pathology in the mouse model. Using genetic and pharmacologic inhibition of IL-1β signaling, we demonstrate that IL-1β lies upstream of disrupted intestinal barrier function, subsequent IgA vasculitis development, and cardiac inflammation. Targeting mucosal barrier dysfunction and the IL-1β pathway may also be applicable to other IgA-related diseases, including IgA vasculitis and IgA nephropathy.
The present research was carried out to investigate the protective effect of total polysaccharides of adlay bran (TPA) on TNF-α-evoked epithelial barrier dysfunction in caco-2 cells. Caco-2 cells were treated with or without TPA in the absence or presence of TNF-α, and transepithelial electrical resistance (TEER) and phenol red flux were assayed to evaluate the intestinal epithelial barrier function. The results indicated that TPA suppressed TNF-α-induced release of pro-inflammatory factors. Furthermore, TPA obviously assuaged both the increased paracellular permeability and the decrease of TEER in TNF-α-challenged Caco-2 cells. Furthermore, TPA obviously assuaged TNF-α-evoked up-regulation of the IL-8 and IL-6 expression, down-regulation of occludin and ZO-3 expression, and markedly suppressed the activation and protein expression of NF-κB p65. Our results indicated that TPA assuages the TNF-α-evoked dysfunction of the intestinal epithelial barrier by inhibiting NF-κB p65-mediated inflammatory response.
The altered expression and subcellular distribution of tight junctions (TJ) proteins, leading to dysfunctional intestinal barrier, is a key mechanistic feature of Inflammatory Bowel Diseases (IBD). Therefore, increasing the integrity of the intestinal barrier by manipulating TJ may constitute an innovative and effective therapeutic strategy in IBD. In this context, recent studies showed that dietary polyphenols are able to protect the intestinal TJ barrier integrity. Here, using a cellular model of intestinal inflammation, consisting of cytokines-stimulated HT-29 colon epithelial cells, we show that a polyphenolic extract obtained from a portuguese red wine (RWE) decreased the paracellular permeability across the cells monolayer compared with the control cells, even in the presence of pro-inflammatory cytokines. The beneficial effect of RWE was exerted at three complementary levels: 1) by promoting a significant increase of the mRNA of key barrier-forming TJ proteins, including occludin, claudin-5 and zonnula occludens (ZO)-1 above the levels observed in control cells; 2) by preventing the decrease of expression of these proteins under inflammatory conditions and 3) by averting the increase of claudin-2 mRNA, a channel-forming TJ protein induced by pro-inflammatory cytokines. Taken together, these results strongly suggest that polyphenols presented and consumed in red wine as a mixture can reinforce and protect the intestinal barrier against inflammatory stimulus by affecting TJ proteins expression and, thus, without the need of purifying individual compounds, might represent a readily available therapeutic intervention against IBD and intestinal inflammation.
The epithelial lining of the gastrointestinal tract serves as the interface for digestion and absorption of nutrients and water and as a defensive barrier. The defensive functions of the intestinal epithelium are remarkable considering that the gut lumen is home to trillions of resident bacteria, fungi and protozoa (collectively, the intestinal microbiota) that must be prevented from translocation across the epithelial barrier. Imbalances in the relationship between the intestinal microbiota and the host lead to the manifestation of diseases that range from disorders of motility and sensation (IBS) and intestinal inflammation (IBD) to behavioural and metabolic disorders, including autism and obesity. The latest discoveries shed light on the sophisticated intracellular, intercellular and interkingdom signalling mechanisms of host defence that involve epithelial and enteroendocrine cells, the enteric nervous system and the immune system. Together, they maintain homeostasis by integrating luminal signals, including those derived from the microbiota, to regulate the physiology of the gastrointestinal tract in health and disease. Therapeutic strategies are being developed that target these signalling systems to improve the resilience of the gut and treat the symptoms of gastrointestinal disease.
The intestinal barrier dysfunction is a critical pathological change in irritable bowel syndrome (IBS). The objective of this study was to evaluate the effect of Prim-O-glucosylcimifugin (POG) on intestinal barrier dysfunction and reveal possible molecular mechanisms. Human colon adenocarcinoma cell line (Caco-2) cell monolayers induced by tryptase (TRYP) were used to establish an intestinal barrier dysfunction model. Caco-2 cell monolayers from both functional and dysfunctional samples were treated with POG (30, 60 and 120 µg/mL) for 2, 8, 24, 36, 48 and 72 h. The Caco-2 cell monolayers were assessed by measurement of trans-epithelial electrical resistance (TEER) and percentage of fluorescein permeation (PFP). The expression of Protease Activated Receptor 2 (PAR-2) and myosin light chain kinase (MLCK) mRNA was analyzed by RT-PCR and the level of Zonula Occludens-1 (ZO-1) protein expression was determined by Western blot. In addition, the impact of POG on the distribution of the tight juction protein of Occludin was performed by immunofluorescence. Our results showed that POG elevated the TEER and decreased the PFP of the functional Caco-2 cell monolayers, as well as the dysfunctional Caco-2 cell monolayers. Furthermore, POG inhibited the expression of PAR-2 mRNA and MLCK mRNA and increased the level of ZO-1 protein expression in dysfunctional Caco-2 cells. The distribution of the Occludin proteins was ameliorated simultaneously. This study demonstrates that POG can enhance the intestinal barrier function of Caco-2 cell monolayers by inhibiting the expression of PAR-2 and MLCK and up-regulating the expression of ZO-1 protein, and ameliorated the distribution of Occludin protein.
Graphical Abstract Fullsize Image
Recent evidence indicates a link between gut pathology and microbiome with hypertension in animal models. However, whether this association exists in humans is unknown. Thus, our objectives in this study were to test the hypotheses that high blood pressure patients have distinct gut microbiomes and that gut epithelial barrier function markers and microbiome composition could predict systolic blood pressure. Fecal samples, analyzed by shotgun metagenomics, displayed taxonomic and functional changes, including altered butyrate production between patients with high blood pressure and reference subjects. Significant increases in plasma of intestinal fatty acid binding protein, lipopolysaccharide, and augmented gut-targeting proinflammatory T helper 17 cells in high blood pressure patients demonstrated increased intestinal inflammation and permeability. Zonulin, a gut epithelial tight junction protein regulator, was markedly elevated, further supporting gut barrier dysfunction in high blood pressure. Zonulin strongly correlated with systolic blood pressure (R2=0.5301, p<0.0001). Two models predicting systolic blood pressure were built using stepwise linear regression analysis of microbiome data and circulating markers of gut health, and validated in a separate cohort by prediction of systolic blood pressure from zonulin in plasma (R2=0.4608, p<0.0001). The mouse model of hypertension, chronic angiotensin II infusion, was used to confirm the effects of butyrate and gut barrier function on the cardiovascular system and blood pressure. These results support our conclusion that intestinal barrier dysfunction and microbiome function are linked to hypertension in humans. They suggest that manipulation of gut microbiome and its barrier functions could be new therapeutic and diagnostic avenues for hypertension.
Lentinula edodes mycelia solid culture extract (MSCE) is used as a medical food ingredient and provides beneficial effects to patients with cancer and chronic type C hepatitis. Low molecular weight lignin (LM-lignin), which is an active component of MSCE, exhibits hepatoprotective, antitumor, antiviral, and immunomodulatory effects. In this study, we investigated the effect of LM-lignin/lignosulfonic acid on intestinal barrier function. Lignosulfonic acid enhanced transepithelial membrane electrical resistance in human intestinal Caco-2 cell monolayers. In Caco-2 cells treated with lignosulfonic acid, expression of claudin-2, which forms high conductive cation pores in tight junctions (TJs), was decreased. Lignosulfonic acid also attenuated the barrier dysfunction that is caused by tumor necrosis factor (TNF)-α and interferon (IFN)-γ in Caco-2 cells. TNF-α- and IFN-γ-induced activation of NF-κB, such as translocation of NF-κB p65 into the nucleus and induction of gene expression, was inhibited by lignosulfonic acid treatment. Furthermore, lignosulfonic acid decreased the TNF-α- and IFN-γ-induced increase in interleukin (IL)-1β and IL-6 expression in Caco-2 cells. These results suggest that lignosulfonic acid not only enhances TJ barrier function but also restores TJ barrier integrity impaired by inflammatory cytokines. Therefore, lignosulfonic acid may be beneficial for the treatment of inflammation-induced intestinal barrier dysfunction observed in inflammatory bowel disease.
In this study, we investigated the glycoproteomics of glycated milk casein (GMC) and GMC fermented by Lactobacillus casei 4B15 (FGMC), and determined their biological implications. There was a significant increase in the antioxidative and anti-inflammatory activities of GMC with galactose, which was higher than that of GMC with glucose (GMC-glc). Further, the fermentation of GMC by Lactobacillus casei 4B15 synergistically enhanced the above activities compared to those of unfermented GMC. Especially, fermented GMC-glc (FGMC-glc) possessed remarkably improved reducing power and radical scavenging activities. Moreover, FGMC-glc ameliorated the inflammatory response and tight junction-related intestinal epithelial dysfunction. Additionally, hexose-derived glycation and modification sites in protein sequences of GMC were identified. In particular, glycosylation and sulfation of serine and threonine residues were observed, and distinct modification sites were detected after fermentation. Therefore, these results indicated that glycation-induced modification of casein and fermentation correlated strongly with the enhanced functional properties.
Dysfunction of the intestinal barrier plays a key role in the pathogenesis of inflammatory bowel disease (IBD) and multiple organ failure. The effect of Alaska pollock skin-derived collagen and its 3 tryptic hydrolytic fractions, HCP (6 kDa retentate), MCP (3 kDa retentate) and LCP (3 kDa permeate) on TNF-α induced barrier dysfunction was investigated in Caco-2 cell monolayers. TNF-α induced barrier dysfunction was significantly attenuated by the collagen and its peptide fractions, especially LCP, compared to TNF-α treated controls (P < 0.05). Compared to a negative control, 24 h pre-incubation with 2 mg mL−1 LCP significantly alleviated the TNF-α induced breakdown of the tight junction protein ZO-1 and occludin and inhibited MLC phosphorylation and MLCK expression. The activation of NFκB and Elk-1 was suppressed by LCP. Thus, collagen peptides may attenuate TNF-α induced barrier dysfunction of Caco-2 cells by inhibiting the NFκB and ERK1/2-mediated MLCK pathway with associated decreases in ZO-1 and occludin protein expression.