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Highsucrose diet (HSD) was reported as a causative factor for multiorgan injuries. The underlying mechanisms and therapeutic strategies remain largely uncharted. In the present study, by using a metabolomics approach, we identified the soluble epoxide hydrolase (sEH) as a therapeutic target for HSD-mediated gut barrier dysfunction. Specifically, 16-week feeding on an HSD caused gut barrier dysfunction, such as colon inflammation and tight junction impairment in a murine model. A metabolomics analysis of mouse colon tissue showed a decrease in the 5(6)-epoxyeicosatrienoic acid [5(6)-EET] level and an increase in soluble epoxide hydrolase, which is related to HSD-mediated injuries to the gut barrier. The mice treated with a chemical inhibitor of sEH and the mice with genetic intervention by intestinal-specific knockout of the sEH gene significantly attenuated HSD-caused intestinal injuries by reducing HSD-mediated colon inflammation and improving the impaired tight junction caused by an HSD. Further, in vitro studies showed that treatment with 5(6)-EET, but not its hydrolytic product 5,6-dihydroxyeicosatrienoic acid (5,6-DiHET), significantly ablated high sucrose-caused intestinal epithelial inflammation and impaired tight junction. Additionally, 5(6)-EET is anti-inflammatory and improves gut epithelial tight junction while 5,6-DiHET cannot do so. This study presents an underlying mechanism of and a therapeutic strategy for the gut barrier dysfunction caused by an HSD., Competing Interests: Competing interests statement:The authors declare no competing interest.

The study evaluates the impact of environmental toxicants, such as polycyclic aromatic hydrocarbons (PAHs), on circadian regulations and functions of brain endothelial cells, which form the main structural element of the blood-brain barrier (BBB). PAH are lipophilic and highly toxic environmental pollutants that accumulate in human and animal tissues. Environmental factors related to climate change, such as an increase in frequency and intensity of wildfires or enhanced strength of hurricanes or tropical cyclones, may lead to redistribution of these toxicants and enhanced human exposure. These natural disasters are also associated with disruption of circadian rhythms in affected populations, linking increased exposure to environmental toxicants to alterations of circadian rhythm pathways. Several vital physiological processes are coordinated by circadian rhythms, and disruption of the circadian clock can contribute to the development of several diseases. The blood-brain barrier (BBB) is crucial for protecting the brain from blood-borne harmful substances, and its integrity is influenced by circadian rhythms. Exposure of brain endothelial cells to a human and environmentally-relevant PAH mixture resulted in dose-dependent alterations of expression of critical circadian modulators, such as Clock, Bmal1, Cry1/2, and Per1/2. Moreover, silencing of the circadian Clock gene potentiated the impact of PAHs on the expression of the main tight junction genes and proteins (namely, claudin-5, occludin, JAM-2, and ZO-2), as well as mitochondrial bioenergetics. Findings from this study contribute to a better understanding of pathological influence of PAH-induced health effects, especially those related to circadian rhythm disruption., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interest or personal relationship that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The pathophysiology of laryngopharyngeal reflux (LPR) and its impact on the vocal fold is not well understood, but may involve acid damage to vocal fold barrier functions. Two different components encompass vocal fold barrier function: the mucus barrier and tight junctions. Mucus retained on epithelial microprojections protects the inside of the vocal fold by neutralizing acidic damage. Tight junctions control permeability between cells. Here we developed an in vitro experimental system to evaluate acidic injury and repair of vocal fold barrier functions. We first established an in vitro model of rat vocal fold epithelium that could survive at least one week after barrier function maturation. The model enabled repeated evaluation of the course of vocal fold repair processes. Then, an injury experiment was conducted in which vocal fold cells were exposed to a 5-min treatment with acidic pepsin that injured tight junctions and cell surface microprojections. Both of them healed within one day of injury. Comparing vocal fold cells treated with acid alone with cells treated with acidic pepsin showed that acidic pepsin had a stronger effect on intercellular permeability than acid alone, whereas pepsin had little effect on microprojections. This result suggests that the proteolytic action of pepsin has a larger effect on protein-based tight junctions than on phospholipids in microprojections. This experimental system could contribute to a better understanding of vocal fold repair processes after chemical or physical injuries, as well as voice problems due to LPR pathogenesis., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Masanobu Mizuta, Ichiro Tateya reports financial support was provided by Japan Society for the Promotion of Science. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Exposure to airborne particulate <10 μm (PM 10 ) adversely affects the ocular surface. This study tested PM 10 on epithelial barrier integrity in immortalized human corneal epithelial cells (HCE-2) and mouse cornea, and whether antioxidant SKQ1 is restorative. HCE-2 were exposed to 100 μg/ml PM 10  ± SKQ1 for 24 h. An Electric Cell-Substrate Impedance Sensing (ECIS) system monitored the impact of PM 10 . RT-PCR, western blotting and immunofluorescence measured levels of barrier and associated proteins, stanniocalcin 2 (STC2), and a kit measured total calcium. In vivo, female C57BL/6 mice were exposed to either control air or PM 10 (±SKQ1) in a whole-body exposure chamber, and barrier associated proteins tested. Tight junction and mucins proteins in the cornea were tested. In HCE-2, PM 0 vs control significantly reduced mRNA and protein levels of tight junction and adherence proteins, and mucins. ECIS data demonstrated that PM 10 vs control cells exhibited a significant decrease in epithelial barrier strength at 4000 Hz indicated by reduced impedance and resistance. PM 10 also upregulated STC2 protein and total calcium levels. In vivo, PM 10 vs control reduced zonula occludens 1 and mucins. SKQ1 pre-treatment reversed PM 10 effects both in vitro and in vivo. In conclusion, PM 10 exposure reduced tight junction and mucin proteins, and compromised the seal between cells in the corneal epithelium leading to decreased epithelial barrier strength. This effect was reversed by SKQ1. Since the corneal epithelium forms the first line of defense against air pollutants, including PM 10 , preserving its integrity using antioxidants such as SKQ1 is crucial in reducing the occurrence of ocular surface disorders., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Linda D. Hazlett reports financial support was provided by National Institutes of Health. Linda D Hazlett reports a relationship with National Institutes of Health that includes: funding grants. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Oleanolic acid (OA) is a naturally occurring pentacyclic triterpene compound that has been reported to cause cholestatic liver injury. However, the regulation and pathogenic role of bile acids in OA-induced development of cholestatic liver injury remains largely unclear. Farnesoid X receptor (FXR) is a metabolic nuclear receptor that plays an important role in bile acid homeostasis in the liver by regulating efflux transporters bile salt export pump (BSEP) and multidrug resistance-associated protein 2 (MRP2). The aim of this study was to investigate the effect of OA on hepatocyte tight junction function and determine the role of FXR, BSEP, and MRP2 in the mechanism of impairment of transport of bile acids induced by OA. Both in vivo and in vitro models were used to characterize the OA-induced liver injury. The liquid chromatography-tandem mass spectrometry (LC-MS) was employed to characterize the efflux function of the transporters, and the results showed that OA caused a blockage of bile acids efflux. OA treatment resulted in decreased expression levels of the tight junction proteins zonula occludens-1 and occludin. Immunofluorescence results showed that OA treatment significantly reduced the number of bile ducts and the immunofluorescence intensity. Pretreatment with agonists of FXR and MRP2, respectively, in animal experiments attenuated OA-induced liver injury, while pretreatment with inhibitors of BSEP and MRP2 further aggravated OA-induced liver injury. These results suggest that OA inhibits FXR-mediated BSEP and MRP2, leading to impaired bile acid efflux and disruption of tight junctions between liver cells, resulting in liver damage., (© 2024 John Wiley & Sons, Ltd.)

The intestinal barrier weakens and chronic gut inflammation occurs in old age, causing age-related illnesses. Recent research shows that low-molecular-weight heparin (LMWH), besides anticoagulation, also has anti-inflammatory and anti-apoptotic effects, protecting the intestinal barrier. This study aims to analyze the effect of LMWH on the intestinal barrier of old male rodents. This study assigned Sprague-Dawley male rats to four groups: young (3 months), young + LMWH, old (20 months), and old + LMWH. The LMWH groups received 1 mg/kg LMWH via subcutaneous injection for 7 days. Optical and transmission electron microscopy (TEM) were used to examine morphological changes in intestinal mucosa due to aging. Intestinal permeability was measured using fluorescein isothiocyanate (FITC)-dextran. ELISA kits were used to measure serum levels of IL-6 and IL-1β, while Quantitative RT-PCR detected their mRNA levels in intestinal tissues. Western blotting and immunohistochemistry (IHC) evaluated the tight junction (TJ) protein levels such as occludin, zonula occludens-1 (ZO-1), and claudin-2. Western blotting assessed the expression of the apoptosis marker cleaved caspase 3, while IHC was used to detect LGR5+ intestinal stem cells. The intestinal permeability of aged rats was significantly higher than that of young rats, indicating significant differences. With age, the protein levels of occludin and ZO-1 decreased significantly, while the level of claudin-2 increased significantly. Meanwhile, our study found that the levels of IL-1β and IL-6 increased significantly with age. LMWH intervention effectively alleviated age-related intestinal barrier dysfunction. In aged rats treated with LMWH, the expression of occludin and ZO-1 proteins in the intestine increased, while the expression of claudin-2 decreased. Furthermore, LMWH administration in aged rats resulted in a decrease in IL-1β and IL-6 levels. LMWH also reduced age-related cleaved caspase3 expression, but IHC showed no difference in LGR5+ intestinal stem cells between groups. Research suggests that LMWH could potentially be a favorable therapeutic choice for age-related diseases associated with intestinal barrier dysfunction, by protecting TJ proteins, reducing inflammation, and apoptosis., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

A long-term exposure to cigarette smoke (CS) alters the integrity of airway epithelial barrier, contributes to lung dysfunction, and elicits the expression and activity of lung cathepsin S (CatS), a cysteine protease that participates in the remodeling of connective tissue and cell junctions. Here, we observed that a short-term (4 days) exposure of mice to CS increased the expression and activity of CatS, while the expression level of zonula occludens 1 (ZO-1), an epithelial tight junction protein that stabilizes barrier assembly, was reduced in lung tissue lysates. Present data support that proteolytically active CatS may contribute to the defect of ZO-1 in CS-exposed mice., (Copyright © 2024 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)

Ulcerative colitis (UC) is a debilitating inflammatory bowel disease characterized by intestinal inflammation, barrier dysfunction, and dysbiosis, with limited treatment options available. This study systematically investigates the therapeutic potential of a synbiotic composed of galactooligosaccharides (GOS) and Limosilactobacillus reuteri in a murine model of colitis, revealing that GOS and L. reuteri synergistically protect against intestinal inflammation and barrier dysfunction by promoting the synthesis of pentadecanoic acid, an odd-chain fatty acid, from Bacteroides acidifaciens. Notably, the synbiotic, B. acidifaciens, and pentadecanoic acid are each capable of suppressing intestinal inflammation and enhancing tight junction by inhibiting NF-κB activation. Furthermore, similar reduction in B. acidifaciens and pentadecanoic acid levels are also observed in the feces from both human UC patients and lipopolysaccharide-induced intestinal inflammation in pigs. Our findings elucidate the protective mechanism of the synbiotic and highlight its therapeutic potential, along with B. acidifaciens and pentadecanoic acid, for UC and other intestinal inflammatory disorders., (© 2024. The Author(s).)

Background: Obesogenic diets cause intestinal inflammation and dysfunction. Polyphenols have shown a positive impact on reducing inflammation in in vitro studies. However, their bioactivity may not be the same in the in vivo system due to structural alteration by the gastrointestinal digestive process. The purpose of this study was to investigate the anti-inflammatory effect of onion peel and its major bioactive compound, quercetin, in the intestine and further examine the impact of intestinal digestion on this effect., Methods: Onion peel extract (OPE) and quercetin (Q) were digested using gastrointestinal digestive enzymes in vitro and then treated into lipopolysaccharide (LPS)-stimulated Caco-2/HT-29 cells. Genes and proteins related to tight junction, inflammation, and epithelial integrity were measured., Results: OPE and digested OPE (DOPE) had a higher protective effect on LPS-induced tight junction and inflammatory genes and paracellular permeability than Q and digested Q (DQ). DOPE was more effective than OPE, while digestion did not change the activity of Q. The anti-inflammatory effect of OPE and Q with or without digestion was achieved by inhibiting nuclear factor kappa B through AMP-activated protein kinase-activated silent mating-type information regulation 2 homolog 1., Conclusions: It was the first to find that a crude extract, after undergoing gastrointestinal digestion, demonstrated a notably superior anti-inflammatory effect in the cell study, suggesting the consumption of onion peels could potentially yield similar benefits in the human intestine. This discovery underscores the potential of onion peel polyphenols in combating intestinal inflammation, making them a compelling area of research for future therapeutic applications using food byproducts.

Arsenic is a widespread environmental contaminant known to accumulate in the brain, leading to cognitive impairment. However, the exact mechanisms by which arsenic causes cognitive deficits remain unclear. The present study aims to discover whether the destruction of the blood-brain barrier (BBB) mediated by matrix metalloproteinases 2 and matrix metalloproteinases 9 (MMP-2 and MMP-9) and subsequent neuronal apoptosis are involved in arsenic-induced cognitive impairment. Ninety male mice were given 0, 25, and 50 mg/L NaAsO 2 in drinking water and 30 mg/kg doxycycline hyclate (DOX, an inhibitor of MMPs) gavage for 12 weeks to observe the alterations in learning and memory of mice, the morphology of hippocampal neurons, as well as the BBB permeability and ultrastructure, the localization and expression of tight junction proteins, MMP-2, and MMP-9. Our findings indicated that arsenic exposure induced learning and memory impairment in mice, accompanied by neuronal loss and apoptosis. Furthermore, arsenic exposure increased hematogenous IgG leakage into the brain, disrupted the tight junctions, reduced the expression of Claudin5, Occludin, and ZO1 in the endothelial cells, and increased the expression of MMP-2 and MMP-9 in the endothelial cells and astrocytes. Finally, DOX intervention preserved BBB integrity, alleviated hippocampal neuronal apoptosis, and improved cognitive impairment in mice caused by arsenic exposure. Our research demonstrates that cognitive disfunction in mice induced by arsenic exposure is associated with MMP-2 and MMP-9-mediated BBB destruction and neuronal apoptosis. The current investigation provides new insights into mechanisms of arsenic neurotoxicity and suggests that MMP-2 and MMP-9 may serve as potential therapeutic targets for treating arsenic-induced cognitive dysfunction in the future., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Cadmium is a contributing factor to cardiovascular diseases and highly toxic to vascular endothelial cells. It has a distinct mode of injury, causing the de-endothelialization of regions in the monolayer structure of endothelial cells in a concentration-dependent manner. However, the specific molecules involved in the cadmium toxicity of endothelial cells remain unclear. The purpose of this study was to identify the specific molecular mechanisms through which cadmium affects endothelial detachment. Cadmium inhibited the expression of claudin-5 and zonula occludens (ZO)-1, which are components of tight junctions (strongest contributors to intercellular adhesion), in a concentration- and time-dependent manner. Compared to arsenite, zinc, and manganese, only cadmium suppressed the expression of both claudin-5 and ZO-1 molecules. Moreover, the knockdown of claudin-5 and ZO-1 exacerbated cadmium-induced endothelial cell injury and expansion of the detachment area, whereas their overexpression reversed these effects. CRE-binding protein inhibition reduced cadmium toxicity, suggesting that CRE-binding protein activation is involved in the cadmium-induced inhibition of claudin-5 and ZO-1 expression and endothelial detachment. These findings provide new insights into the toxicological mechanisms of cadmium-induced endothelial injury and risk of cardiovascular disease.

Allergens and Th2 cytokines affect the homeostatic environment in the airways, leading to increased mucus production by goblet cells associated with altered adherens junctional complex (AJC) and tight junction (TJ) proteins responsible for maintaining epithelial barrier function. Circadian clock-dependent regulatory mechanisms such as inflammation and epithelial barrier function are gaining more attention due to their therapeutic potential against allergic inflammatory lung diseases. Currently, there are no studies to support whether REV-ERBα activation can attenuate Th2 cytokine-induced epithelial barrier dysfunction in human bronchial epithelial cells. We hypothesized that Th2 cytokine-induced epithelial barrier dysfunction may be protected by activating REV-ERBα. Treatment with Th2 cytokines or HDM significantly reduced the cell impedance, as confirmed by transepithelial electrical resistance (TEER). However, pre-treatment with SR10067 attenuated Th2 cytokine-induced barrier dysfunction, such as decreased permeability, improved TEER, localization of AJC and TJ proteins, and mRNA and protein levels of selected epithelial barrier and circadian clock targets. Overall, we showed for the first time that REV-ERBα activation regulates altered epithelial barrier function that may have direct implications for the treatment of asthma and other allergic diseases., (© 2024 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

Objective: To investigate the mechanism of the protective effect of modified Pulsatilla decoction (, MPD) on the mechanical barrier of the ulcerative colitis (UC) intestinal epithelium in vitro and in vivo ., Methods: We established an intestinal epithelial crypt cell line-6 cell barrier injury model by using lipopolysaccharide (LPS). The model was then treated with p38 mitogen-activated protein kinase-myosin light chain kinase (p38MAPK-MLCK) pathway inhibitors, p38MAPK-MLCK pathway silencing genes (si-p38MAPK, si-NF-κB, and si-MLCK), and MPD respectively. Transepithelial electronic resistance (TEER) measurements and permeability assays were performed to assess barrier function. Immunofluorescence staining of tight junctions (TJ) was performed. In in vivo experiment, dextran sodium sulfate-induced colitis rat model was conducted to evaluate the effect of MPD and mesalazine on UC. The rats were scored using the disease activity index based on their clinical symptoms. Transmission electron microscopy and hematoxylin-eosin staining were used to examine morphological changes in UC rats. Western blotting and real-time quantitative polymerase chain reaction were performed to examine the gene and protein expression of significant differential molecules., Results: In in vitro study, LPS-induced intestinal barrier dysfunction was inhibited by p38MAPK-MLCK pathway inhibitors and p38MAPK-MLCK pathway gene silencing. Silencing of p38MAPK-MLCK pathway genes decreased TJ expression. MPD treatment partly restored the LPS-induced decreased in TEER and increase in permeability. MPD increased the gene and protein expression of TJ, while down-regulated the LPS-induced high expression of p-p38MAPK and p-MLC. In UC model rats, MPD could ameliorate body weight loss and disease activity index, relieve colonic pathology, up-regulate TJ expression as well as decrease the expression of p-p38MAPK and p-MLC in UC rat colonic mucosal tissue., Conclusions: The p38MAPK-MLCK signaling pathway can affect mechanical barrier function and TJ expression in the intestinal epithelium. MPD restores TJ expression and attenuates intestinal epithelial barrier damage by suppressing the p38MAPK-MLCK pathway.

Intestinal permeabilization is central to the pathophysiology of chronic gut inflammation. This study investigated the efficacy of glucoraphanin (GR), prevalent in cruciferous vegetables, particularly broccoli, and its derivative sulforaphane (SF), in inhibiting tumor necrosis factor alpha (TNFα)-induced Caco-2 cell monolayers inflammation and permeabilization through the regulation of redox-sensitive events. TNFα binding to its receptor led to a rapid increase in oxidant production and subsequent elevation in the mRNA levels of NOX1, NOX4, and Duox2. GR and SF dose-dependently mitigated both these short- and long-term alterations in redox homeostasis. Downstream, GR and SF inhibited the activation of the redox-sensitive signaling cascades NF-κB (p65 and IKK) and MAPK ERK1/2, which contribute to inflammation and barrier permeabilization. GR (1 μM) and SF (0.5-1 μM) prevented TNFα-induced monolayer permeabilization and the associated reduction in the levels of the tight junction (TJ) proteins occludin and ZO-1. Both GR and SF also mitigated TNFα-induced increased mRNA levels of the myosin light chain kinase, which promotes TJ opening. Molecular docking suggests that although GR is mostly not absorbed, it could interact with extracellular and membrane sites in NOX1. Inhibition of NOX1 activity by GR would mitigate TNFα receptor downstream signaling and associated events. These findings support the concept that not only SF, but also GR, could exert systemic health benefits by protecting the intestinal barrier against inflammation-induced permeabilization, in part by regulating redox-sensitive pathways. GR has heretofore not been viewed as a biologically active molecule, but rather, the benign precursor of highly active SF. The consumption of GR and/or SF-rich vegetables or supplements in the diet may offer a means to mitigate the detrimental consequences of intestinal permeabilization, not only in disease states but also in conditions characterized by chronic inflammation of dietary and lifestyle origin., Competing Interests: Declaration of competing interest Authors have no conflict of interest to declare., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Advanced glycation end products (AGEs) are a spectrum of complex compounds widely found in processed foods and frequently consumed by humans. AGEs are implicated in impairing the intestinal barrier, but the underlying mechanisms remain unclear. This study investigated the effects of three types of AGEs on gene expression of tight junctions (TJs) in colorectal epithelial HT-29 cells, and observed minimal alterations in TJs expression. Given the important role of subepithelial macrophages in regulating the intestinal barrier, we explored whether AGEs affect the intestinal barrier via the involvement of macrophages. Notably, a significant downregulation of TJs expression was observed when supernatants from AGEs-treated RAW264.7 macrophage cells were transferred to HT-29 cells. Further investigations indicated that AGEs increased IL-6 levels in RAW264.7 cells, subsequently triggering STAT3 activation and suppressing TJs expression in HT-29 cells. The role of STAT3 activation was confirmed by observing enhanced TJs expression in HT-29 cells following pretreatment with an inhibitor of STAT3 activation prior to the transfer of the conditioned medium. These findings demonstrated that AGEs impaired the intestinal barrier via macrophage-mediated STAT3 activation, shedding light on the mechanisms underlying AGEs-induced intestinal barrier injury and related food safety risks., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: Mycoplasma gallisepticum (MG) has long been a pathogenic microorganism threatening the global poultry industry. Previous studies have demonstrated that the mechanism by which quercetin (QUE) inhibits the colonization of MG in chicks differs from that of antibiotics. However, the molecular mechanism by which QUE facilitates the clearance of MG remains unclear., Purpose: The aim of this study was to investigate the molecular mechanism of MG clearance by QUE, with the expectation of providing new options for the treatment of MG., Methods: A model of MG infection in chicks and MG-induced M1 polarization in HD-11 cells were established. The mechanism of QUE clearance of MG was investigated by evaluating the relationship between tracheal mucosal barrier integrity, antibody levels, Th1/Th2 immune balance and macrophage metabolism and M1/M2 polarization balance. Furthermore, network pharmacology and molecular docking techniques were employed to explore the potential molecular pathways connecting QUE, M2 polarization, and fatty acid oxidation (FAO)., Results: The findings indicate that QUE remodels tracheal mucosal barrier function by regulating tight junctions and secretory immunoglobulin A (sIgA) expression levels. This process entails the regulatory function of QUE on the Th1/Th2 immune imbalance that is induced by MG infection in the tracheal mucosa. Moreover, QUE intervention impeded the M1 polarization of HD-11 cells induced by MG infection, while simultaneously promoting M2 polarization through the induction of FAO. Conversely, inhibitors of the FAO pathway impede this effect. The results of computer network analysis suggest that QUE may induce FAO via the PI3K/AKT pathway to promote M2 polarization. Notably, inhibition of the PI3K/AKT pathway was found to effectively inhibit M2 polarization in HD-11 cells, while having a limited effect on FAO., Conclusions: QUE promotes M2 polarization of HD-11 cells to enhance Th2 immune response through FAO and PI3K/AKT pathways, thereby restoring tracheal mucosal barrier function and ultimately inhibiting MG colonization., Competing Interests: Declaration of competing interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Confluent populations of the epithelial cell line, MDCK II, develop circumferential tight junctions joining adjacent cells to create a barrier to the paracellular movement of solutes and water. Treatment of MDCK II cell populations from the apical surface with 1 mM Na-caprate increased permeability to macromolecules (Leak Pathway) without increasing monolayer disruption or cell death. Graphical analysis of the apparent permeability versus solute Stokes radius for a size range of fluorescein-dextran species indicates apical 1 mM Na-caprate enhances Leak Pathway permeability by increasing the number of Leak Pathway openings without significantly affecting opening size. Na-caprate treatment did not alter the content of any tight junction protein examined. Treatment of MDCK II cell populations with apical 1 mM Na-caprate disrupted basal F-actin stress fibers and decreased the tortuosity of the tight junctions. Treatment of MDCK II cell populations with blebbistatin, a myosin ATPase inhibitor, alone had little effect on Leak Pathway permeability but synergistically increased Leak Pathway permeability when added with 1 mM Na-caprate. Na-caprate exhibited a similar ability to increase Leak Pathway permeability in wild-type MDCK II cell monolayers and ZO-1 knockdown MDCK II cell monolayers but an enhanced ability to increase Leak Pathway permeability in monolayers of TOCA-1 knockout MDCK II cells. These results demonstrate that Na-caprate increases MDCK II cell population Leak Pathway permeability by increasing the number of Leak Pathway openings. This action is likely mediated by alterations in F-actin organization, primarily involving disruption of basal F-actin stress fibers. NEW & NOTEWORTHY This study determines the underlying change in the openings in the epithelial tight junction permeability barrier structure that leads to a change in the paracellular permeability to macromolecules (the Leak Pathway) and connects this to disruption of specific F-actin structures within the cells. It provides important and novel insights into how tight junction permeability to macromolecules is modulated by specific changes to cellular and tight junction composition/organization.

Bezafibrate (BEZ) has displayed a wide range of neuroprotective effects in different types of neurological diseases. However, its pharmacological function in traumatic brain injury (TBI) is still unknown. In the current study, a TBI model was constructed in mice to examine the potential beneficial roles of BEZ. After TBI, mice were daily dieted with BEZ or vehicle solution. The motor function, learning and memory, brain edema, vascular inflammatory factors, the integrity of the blood-brain barrier (BBB), and the expression of the tight junction zona occludens 1 (ZO-1) were assessed. The findings demonstrate that after TBI, BEZ treatment significantly promoted the recovery of motor function and cognitive function deficits. Moreover, BEZ attenuated brain edema by reducing the levels of brain water content. We also found that administration of BEZ alleviated cerebral vascular pro-inflammation by suppressing the expression of ICAM-1, VCAM-1, and E-selectin. Notably, BEZ improved the impaired BBB integrity in TBI mice by restoring the expression of the tight junction (TJ) protein ZO-1. Further in vitro experiments show that treatment with BEZ prevented the aggravation of endothelial permeability and restored the reduction of trans-epithelial electrical resistance (TEER) as well as the expression of ZO-1 in TBI-exposed brain bEnd.3 cells. Mechanistically, we prove that the protective effects of BEZ are mediated by AMPK. Based on these findings, we conclude that BEZ improves TBI-induced BBB injury and it might be considered for the treatment or management of TBI., (Copyright © 2024. Published by Elsevier Ltd.)

Intestinal barrier dysfunction characterized by the functional loss of the intestinal epithelium's tight junction (TJ) barrier is a key factor in the pathogenesis of ulcerative colitis (UC). Although rapamycin, an mTOR (mechanistic target of rapamycin) inhibitor, has shown promise in inducing clinical remission and mucosal healing in inflammatory bowel disease, its underlying mechanism remains elusive. Thus, this study investigated the role of the mTOR pathway in regulating the intestinal barrier. To investigate the molecular mechanism regulating the intestinal barrier, specific intestinal epithelial phenazine biosynthesis-like domain-containing protein (PBLD)-deficient (PBLD IEC-/- ) mice and control wild-type (WT) mice were intraperitoneally injected with rapamycin or MHY1485. To determine the relevance of the findings for UC, we analyzed transcriptome data and single-cell expression profiles from public databases and intestinal mucosal tissues obtained from patients with active UC or colon cancer. We observed that mTOR activation in the intestinal epithelium of patients with active UC. Moreover, in vivo, rapamycin markedly increased the expressions of PBLD and TJ proteins and reduced intestinal inflammation in mice with dextran sulfate sodium-induced enteritis. However, the therapeutic efficacy of rapamycin was notably reduced in PBLD IEC-/- mice. In vitro, rapamycin influenced PBLD expression by modulating the nuclear transcription of transcription factor EB (TFEB). Angiomotin (AMOT) could directly bind to PBLD, and rapamycin could not effectively increase the expression of TJ proteins after the knockdown of PBLD or AMOT. In summary, the administration of rapamycin is a potential treatment for UC, and targeting the mTOR/PBLD/AMOT axis is a potential novel approach for UC treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Organophosphate flame retardants 2-ethylhexyldiphenyl phosphate (EHDPP) and cadmium (Cd) are ubiquitous in environmental matrices, and dermal absorption is a major human exposure pathway. However, their detrimental effects on the human epidermis remain largely unknown. In this study, human keratinocytes (HaCaT cells) were employed to examine the toxicity and underlying mechanisms of co-exposure to EHDPP and Cd. Their influence on cell morphology and viability, oxidative damage, apoptosis, and tight junction were determined. The results showed that co-exposure decreased cell viability by >40 %, induced a higher level of oxidative damage by increasing the generation of reactive oxygen species (1.3 folds) and inhibited CAT (79 %) and GPX (90 %) activities. Moreover, Cd exacerbated EHDPP-induced mitochondrial disorder and cellular apoptosis, which was evidenced by a reduction in mitochondrial membrane potential and an elevation of cyt-c and Caspase-3 mRNA expression. In addition, greater loss of ZO-1 immunoreactivity at cellular boundaries was observed after co-exposure, indicating skin epithelial barrier function disruption, which may increase the human bioavailability of contaminants via the dermal absorption pathway. Taken together, oxidative damage, cell apoptosis, and tight junction disruption played a crucial role in EHDPP + Cd triggered cytotoxicity in HaCaT cells. The detrimental effects of EHDPP + Cd co-exposure were greater than individual exposure, suggesting the current health risk assessment or adverse effects evaluation of individual exposure may underestimate their perniciousness. Our data imply the importance of considering the combined exposure to accurately assess their health implication., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Recent advancements in canine intestinal organoid research have paved the way for the development of enhanced in vitro models, crucial for exploring intestinal physiology and diseases. Despite these strides, there is a notable gap in creating specific in vitro models that focus on intestinal inflammation. Our study aims to bridge this gap by investigating the impact of proinflammatory cytokines on canine intestinal epithelial cells (IECs) within the context of organoid models. Canine intestinal organoids were treated with proinflammatory cytokines TNF-α, IFN-γ, and IL-1β. The expression of stem cell markers Lgr5, Sox9, Hopx, and Olfm4 was evaluated through RT-qPCR, while membrane integrity was assessed using immunofluorescence staining for tight junction proteins and transport assays for permeability. IFN-γ significantly decreased Lgr5 expression, a key intestinal stem cell marker, at both 24 and 48 h post-treatment (p=0.030 and p=0.002, respectively). Conversely, TNF-α increased Olfm4 expression during the same intervals (p=0.018 and p=0.011, respectively). A reduction in EdU-positive cells, indicative of decreased cell proliferation, was observed following IFN-γ treatment. Additionally, a decrease in tight junction proteins E-cadherin and ZO-1 (p<0.001 and p=0.003, respectively) and increased permeability in IECs (p=0.012) were noted, particularly following treatment with IFN-γ. The study highlights the profound impact of proinflammatory cytokines on canine IECs, influencing both stem cell dynamics and membrane integrity. These insights shed light on the intricate cellular processes underlying inflammation in the gut and open avenues for more in-depth research into the long-term effects of inflammation on intestinal health., (© 2024. The Author(s).)

Despite of yet unknown mechanism, microvascular deposition of oligomeric Tau (oTau) has been implicated in alteration of the Blood-Brain Barrier (BBB) function in Alzheimer's disease (AD) brains. In this study, we employed an in vitro BBB model using primary mouse cerebral endothelial cells (CECs) to investigate the mechanism underlying the effects of oTau on BBB function. We found that exposing CECs to oTau induced oxidative stress through NADPH oxidase, increased oxidative damage to proteins, decreased proteasome activity, and expressions of tight junction (TJ) proteins including occludin, zonula occludens-1 (ZO-1) and claudin-5. These effects were suppressed by the pretreatment with Fasudil, a RhoA/ROCK signaling inhibitor. Consistent with the biochemical alterations, we found that exposing the basolateral side of CECs to oTau in the BBB model disrupted the integrity of the BBB, as indicated by an increase in FITC-dextran transport across the model, and a decrease in trans endothelial electrical resistance (TEER). oTau also increased the transmigration of peripheral blood mononuclear cells (PBMCs) in the BBB model. These functional alterations in the BBB induced by oTau were also suppressed by Fasudil. Taken together, our findings suggest that targeting the RhoA/ROCK pathway can be a potential therapeutic strategy to maintain BBB function in AD., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Inc.)

The expected increments in the production/use of bioplastics, as an alternative to petroleum-based plastics, require a deep understanding of their potential environmental and health hazards, mainly as nanoplastics (NPLs). Since one important exposure route to NPLs is through inhalation, this study aims to determine the fate and effects of true-to-life polylactic acid nanoplastics (PLA-NPLs), using the in vitro Calu-3 model of bronchial epithelium, under air-liquid interphase exposure conditions. To determine the harmful effects of PLA-NPLs in a more realistic scenario, both acute (24 h) and long-term (1 and 2 weeks) exposures were used. Flow cytometry results indicated that PLA-NPLs internalized easily in the barrier (∼10 % at 24 h and ∼40 % after 2 weeks), which affected the expression of tight-junctions formation (∼50 % less vs control) and the mucus secretion (∼50 % more vs control), both measured by immunostaining. Interestingly, significant genotoxic effects (DNA breaks) were detected by using the comet assay, with long-term effects being more marked than acute ones (7.01 vs 4.54 % of DNA damage). When an array of cellular proteins including cytokines, chemokines, and growth factors were used, a significant over-expression was mainly found in long-term exposures (∼20 proteins vs 5 proteins after acute exposure). Overall, these results described the potential hazards posed by PLA-NPLs, under relevant long-term exposure scenarios, highlighting the advantages of the model used to study bronchial epithelium tissue damage, and signaling endpoints related to inflammation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

A general platform for the safe and effective oral delivery of biologics would revolutionize the administration of protein-based drugs, improving access for patients and lowering the financial burden on the health-care industry. Because of their dimensions and physiochemical properties, nanomaterials stand as promising vehicles for navigating the complex and challenging environment in the gastrointestinal (GI) tract. Recent developments have led to materials that protect protein drugs from degradation and enable controlled release in the small intestine, the site of absorption for most proteins. Yet, once present in the small intestine, the protein must transit through the secreted mucus and epithelial cells of the intestinal mucosa into systemic circulation, a process that remains a bottleneck for nanomaterial-based delivery. One attractive pathway through the intestinal mucosa is the paracellular route, which avoids cell trafficking and other degradative processes in the interior of cells. Direct flux between cells is regulated by epithelial tight junctions (TJs) that seal the paracellular space and prevent protein flux. Here, we describe a smart nanoparticle system that directly and transiently disrupts TJs for improved protein delivery, an unrealized goal to-date. We take inspiration from enteropathogenic bacteria that adhere to intestinal epithelia and secrete inhibitors that block TJ interactions in the local environment. To mimic these natural mechanisms, we engineer nanoparticles (EnteroPatho NPs) that attach to the epithelial glycocalyx and release TJ modulators in response to the intestinal pH. We show that EnteroPatho NPs lead to TJ disruption and paracellular protein delivery, giving rise to a general platform for oral delivery.

Per- and polyfluoroalkyl substances (PFASs) are a family of "forever chemicals" including perfluorooctane sulfonate (PFOS). These toxic chemicals do not break down in the environment or in our bodies. In the human body, PFOS and perfluoroctanoic acid (PFOA) have a half-life ( T 1/2 ) of about 4-5 yr so low daily consumption of these chemicals can accumulate in the human body to a harmful level over a long period. Although the use of PFOS in consumer products was banned in the United States in 2022/2023, this forever chemical remains detectable in our tap water and food products. Every American tested has a high level of PFAS in their blood (https://cleanwater.org/pfas-forever-chemicals). In this report, we used a Sertoli cell blood-testis barrier (BTB) model with primary Sertoli cells cultured in vitro with an established functional tight junction (TJ)-permeability barrier that mimicked the BTB in vivo. Treatment of Sertoli cells with PFOS was found to perturb the TJ-barrier, which was the result of cytoskeletal disruption across the cell cytoplasm, disrupting actin and microtubule polymerization. These changes thus affected the proper localization of BTB-associated proteins at the BTB. Using RNA-Seq transcriptome profiling, bioinformatics analysis, and pertinent biochemical and cell biology techniques, it was discovered that PFOS -induced Sertoli cell toxicity through the c-Jun N-terminal kinase (JNK; also known as stress-activated protein kinase, SAPK) and its phosphorylated/active form p-JNK signaling pathway. More importantly, KB-R7943 mesylate (KB), a JNK/p-JNK activator, was capable of blocking PFOS-induced Sertoli cell injury, supporting the notion that PFOS-induced cell injury can possibly be therapeutically managed. NEW & NOTEWORTHY PFOS induces Sertoli cell injury, including disruption of the 1 ) blood-testis barrier function and 2 ) cytoskeletal organization, which, in turn, impedes male reproductive function. These changes are mediated by JNK/p-JNK signaling pathway. However, the use of KB-R7943, a JNK/p-JNK activator was capable of blocking PFOS-induced Sertoli cell injury, supporting the possibility of therapeutically managing PFOS-induced reproductive dysfunction.

Tight junction disruption can lead to pathogenesis of various diseases without therapeutic strategy to recover intestinal barrier integrity. The main objective of this study is to demonstrate the effect of Solanum melongena L. extract (SMLE) on intestinal tight junction recovery and its underlying mechanism. Intestinal barrier function is attenuated by Ca 2+ depletion. SMLE treatment increased TER value across T84 cell monolayers. Permeability assay reveals that Ca 2+ depletion promotes 4-kDa FITC-dextran permeability, but not 70-kDa FITC-dextran. SMLE suppresses the rate of 4-kDa FITC-dextran permeability, indicating that SMLE inhibits paracellular leak pathway permeability. SMLE-mediated TER increase and leak pathway suppression are abolished by neither calcium/calmodulin-dependent protein kinase kinase β (CaMKKβ) inhibitor nor AMP-activated protein kinase (AMPK) inhibitor. Furthermore, mammalian target of rapamycin (mTOR) and extracellular signal-regulated kinase (ERK) inhibitors have no effects on SMLE-mediated TER increase and leak pathway suppression. Interestingly, SMLE is unable to enhance TER value and diminish leak pathway permeability in T84 cell monolayers pre-treated with sirtuin-1 (SIRT-1) inhibitor. Immunofluorescence staining reveals that SMLE enhances re-assembly of tight junction proteins, including occludin and ZO-1 to intercellular space but this effect is abolished by SIRT-1 inhibitor. These data suggest that SMLE promotes intestinal tight junction re-assembly via SIRT-1-dependent manner., (© 2024 Wiley‐VCH GmbH.)

Obstructive jaundice (OJ) can cause multiple pathophysiological consequences including intestinal barrier dysfunction. Omega-3 has been indicated to have a promising therapeutic effect on OJ. This study aimed to further investigate the functions of omega-3 on OJ-induced intestinal injury. A rat OJ model was established by bile duct ligation with or without omega-3 administration. ELISA was utilized for measuring serum levels of inflammatory cytokines. Hematoxylin-eosin staining and TUNEL staining were employed for detecting the morphological changes and cell apoptosis in rat intestine. Western blotting was utilized for evaluating expression of tight junction proteins in the intestinal tissues. Omgea-3 offset the reduction in body weight of OJ rats. Omega-3 alleviated inflammatory response, pathological damages and cell apoptosis in the intestine of OJ rats. Additionally, omega-3 enhanced levels of tight junction proteins in the intestinal tissues of OJ rats. Omega-3 ameliorates OJ-triggered impairment of intestinal barrier function in rats., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Tight junctional complexes (TJCs) between cerebral microvascular endothelial cells (CMECs) are essential parts of the blood-brain barrier (BBB), whose regulation closely correlates to the BBB's integrity and function. hCMEC/D3 is the typical cell line used to imitate and investigate the barrier function of the BBB via the construction of an in vitro model. This study aims to investigate the protective effect of the deep-sea-derived fibrinolytic compound FGFC1 against H 2 O 2 -induced dysfunction of TJCs and to elucidate the underlying mechanism. The barrier function was shown to decline following exposure to 1 mM H 2 O 2 in an in vitro model of hCMEC/D3 cells, with a decreasing temperature-corrected transendothelial electrical resistance (tcTEER) value. The decrease in the tcTEER value was significantly inhibited by 80 or 100 µM FGFC1, which suggested it efficiently protected the barrier integrity, allowing it to maintain its function against the H 2 O 2 -induced dysfunction. According to immunofluorescence microscopy (IFM) and quantitative real-time polymerase chain reaction (qRT-PCR), compared to the H 2 O 2 -treated group, 80~100 µM FGFC1 enhanced the expression of claudin-5 (CLDN-5) and VE-cadherin (VE-cad). And this enhancement was indicated to be mainly achieved by both up-regulation of CLDN-5 and inhibition of the down-regulation by H 2 O 2 of VE-cad at the transcriptional level. Supported by FGFC1's molecular docking to these proteins with reasonable binding energy, FGFC1 was proved to exert a positive effect on TJCs' barrier function in hCMEC/D3 cells via targeting CLDN-5 and VE-cad. This is the first report on the protection against H 2 O 2 -induced barrier dysfunction by FGFC1 in addition to its thrombolytic effect. With CLDN-5 and VE-cad as the potential target proteins of FGFC1, this study provides evidence at the cellular and molecular levels for FGFC1's reducing the risk of bleeding transformation following its application in thrombolytic therapy for cerebral thrombosis.

Background: Colitis is a refractory intestinal inflammatory disease significantly affecting the quality of a patient's life and increasing the risk of exacerbation. The primary factors leading to colitis encompass infections, insufficient blood flow, and the buildup of collagen as well as white blood cells. Among various available therapeutics, 5-methoxytryptophan (5-MTP) has emerged as one of the protectants by inhibiting inflammatory damage. Nonetheless, there is no report on the role of 5-MTP in the treatment of colitis., Materials and Methods: To verify the anti-inflammatory effect of 5-MTP in vivo , we first constructed mouse model with dextran sulfate sodium-induced colitis. Furthermore, the macrophage infiltration and release of inflammatory factors through western blot (WB) and hematoxylin-eosin staining analyses were examined. Intestinal epithelial cell tight junction damage and apoptosis were investigated by WB analysis, immunofluorescence, and terminal deoxynucleotidyl transferase dUTP nick end labeling staining. Finally, we examined the generation of cellular inflammation and analyzed the influence of 5-MTP on M1 polarization at the cellular level., Results: This study initially confirmed that 5-MTP possessed an excellent therapeutic effect on colitis. 5-MTP inhibits macrophage infiltration and the generation of inflammatory factors. In addition to its effects on immune cells, 5-MTP significantly inhibits intestinal epithelial cell tight junction damage and apoptosis in vivo . Moreover, it inhibits inflammation and M1 polarization response in vitro ., Conclusion: 5-MTP counteracts excessive inflammation, thereby preventing intestinal epithelial tight junction damage. In addition, inhibition of apoptosis suggests that 5-MTP may be a potential therapeutic agent for colitis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflicts of interest., (Copyright © 2024 Yanling Wang et al.)

Sertoli cells (SCs) maintain testicular homeostasis and promote spermatogenesis by forming the blood-testis barrier (BTB) and secreting growth factors. The pro-proliferative and anti-apoptotic effects of nerve growth factor (NGF) on SCs have been proved previously. It is still unclear whether the damage effect of arsenic on testis is related to the inhibition of NGF expression, and whether NGF can mitigate arsenic-induced testicular damage by decreasing the damage of SCs induced by arsenic. Here, the lower expression of NGF in testes of arsenic exposed mice (freely drinking water containing 15 mg/l of NaAsO 2 ) was observed through detection of Western blot and Real-time PCR. Subsequently, hematoxylin and eosin (HE) staining, Evans blue staining and transmission electron microscopy were used to evaluate the pathology, BTB permeability and tight junction integrity in testes of control mice, arsenic exposed mice (freely drinking water containing 15 mg/l of NaAsO 2 ) and arsenic + NGF treated mice (freely drinking water containing 15 mg/l of NaAsO 2 + intraperitoneal injection with 30 μg/kg of NGF), respectively. Evidently, spermatogenic tubule epithelial cells in testis of arsenic exposed mice were disordered and the number of cell layers was reduced, accompanied by increased permeability and damaged integrity of the tight junction in BTB, but these changes were less obvious in testes of mice treated with arsenic + NGF. In addition, the sperm count, motility and malformation rate of mice treated with arsenic + NGF were also improved. On the basis of the above experiments, the viability and apoptosis of primary cultured SCs treated with arsenic (10 μM NaAsO 2 ) or arsenic + NGF (10 μM NaAsO 2 + 100 ng/mL NGF) were detected by Cell counting kit-8 (CCK8) and transferase-mediated DUTP-biotin nick end labeling (TUNEL) staining, respectively. It is found that NGF ameliorated the decline of growth activity and the increase of apoptosis in arsenic-induced SCs. This remarkable biological effect that NGF inhibited the increase of Bax expression and the decrease of Bcl-2 expression in arsenic-induced SCs was also determined by western blot and Real-time PCR. Moreover, the decrease in transmembrane resistance (TEER) and the expression of tight junction proteins ZO-1 and occludin was mitigated in SCs induced by arsenic due to NGF treatment. In conclusion, the above results confirmed that NGF could ameliorate the injury effects of arsenic on testis, which might be related to the function of NGF to inhibit arsenic-induced SCs injury., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: This study aimed to investigate the impact of hepatocyte growth factor (HGF) on colonic morphology and gut microbiota in a rat model of short bowel syndrome (SBS)., Methods: SD rats underwent jugular vein catheterization for total parenteral nutrition (TPN) and 90% small bowel resection [TPN + SBS (control group) or TPN + SBS + intravenous HGF (0.3 mg/kg/day, HGF group)]. Rats were harvested on day 7. Colonic morphology, gut microflora, tight junction, and Toll-like receptor-4 (TLR4) were evaluated., Results: No significant differences were observed in the colonic morphological assessment. No significant differences were observed in the expression of tight junction-related genes in the proximal colon. However, the claudin-1 expression tended to increase and the claudin-3 expression tended to decrease in the distal colon of the HGF group. The Verrucomicrobiota in the gut microflora of the colon tended to increase in the HGF group. The abundance of most LPS-producing microbiota was lower in the HGF group than in the control group. The gene expression of TLR4 was significantly downregulated in the distal colon of the HGF group., Conclusion: HGF may enhance the mucus barrier through the tight junctions or gut microbiome in the distal colon., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Circadian rhythm plays an important role in intestinal homeostasis and intestinal immune function. Circadian rhythm dysregulation was reported to induce intestinal microbiota dysbiosis, intestinal barrier disruption, and trigger intestinal inflammation. However, the relationship between intestinal microbiota metabolites and the circadian rhythm of the intestinal barrier was still unclear. Urolithin A (UA), a kind of intestinal microbial metabolite, was selected in this study. Results showed UA influenced on the expression rhythm of the clock genes BMAL1 and PER2 in intestinal epithelial cells. Furthermore, the study investigated the effects of UA on the expression rhythms of clock genes ( BMAL1 and PER2 ) and tight junctions ( OCLN , TJP1 , and CLND1 ), all of which were dysregulated by inflammation. In addition, UA pre-treatment by oral administration to female C57BL/6 mice showed the improvement in the fecal IgA concentrations, tight junction expression ( Clnd1 and Clnd4 ), and clock gene expression ( Bmal1 and Per2 ) in a DSS-induced colitis model induced using DSS treatment. Finally, the Nrf2-SIRT1 signaling pathway was confirmed to be involved in UA's effect on the circadian rhythm of intestinal epithelial cells by antagonist treatment. This study also showed evidence that UA feeding showed an impact on the central clock, which are circadian rhythms in SCN. Therefore, this study highlighted the potential of UA in treating diseases like IBD with sleeping disorders by improving the dysregulated circadian rhythms in both the intestinal barrier and the SCN.

Alpinia officinarum Hance is rich in carbohydrates and is flavored by natives. The polysaccharide fraction 30 is purified from the rhizome of A. officinarum Hance (AOP30) and shows excellent immunoregulatory ability when administered to regulate immunity. However, the effect of AOP30 on the intestinal epithelial barrier is not well understood. Therefore, the aim of this study is to investigate the protective effect of AOP30 on the intestinal epithelial barrier using a lipopolysaccharide (LPS)-induced intestinal epithelial barrier dysfunction model and further explore its underlying mechanisms. Cytotoxicity, transepithelial electrical resistance (TEER) values, and Fluorescein isothiocyanate (FITC)-dextran flux are measured. Simultaneously, the protein and mRNA levels of tight junction (TJ) proteins, including zonula occludens-1 (ZO-1), Occludin, and Claudin-1, are determined using Western blotting and reverse-transcription quantitative polymerase chain reaction methods, respectively. The results indicate that AOP30 restores the LPS-induced decrease in the TEER value and cell viability. Furthermore, it increases the mRNA and protein expression of ZO-1, Occludin, and Claudin-1. Notably, ZO-1 is the primary tight junction protein altered in response to LPS-induced intestinal epithelial dysfunction. Additionally, AOP30 downregulates the production of TNFα via the Toll-like receptor 4 (TLR4)/NF-κB signaling pathway. Collectively, the findings of this study indicate that AOP30 can be developed as a functional food ingredient or natural therapeutic agent for addressing intestinal epithelial barrier dysfunction. It sheds light on the role of AOP30 in improving intestinal epithelial function.

Background: Diarrheal irritable bowel syndrome (IBS-D), characterized primarily by the presence of diarrhea and abdominal pain, is a clinical manifestation resulting from a multitude of causative factors. Furthermore, Sishen Wan (SSW) has demonstrated efficacy in treating IBS-D. Nevertheless, its mechanism of action remains unclear., Methods: A model of IBS-D was induced by a diet containing 45 % lactose and chronic unpredictable mild stress. Additionally, the impact of SSW was assessed by measuring body weight, visceral sensitivity, defecation parameters, intestinal transport velocity, intestinal neurotransmitter levels, immunohistochemistry, and transmission electron microscopy analysis. Immunofluorescent staining was used to detect the expression of Mucin 2 (MUC2) and Occludin in the colon. Western blotting was used to detect changes in proteins related to tight junction (TJ), autophagy, and endoplasmic reticulum (ER) stress in the colon. Finally, 16S rRNA amplicon sequencing was used to monitor the alteration of gut microbiota after SSW treatment., Results: Our study revealed that SSW administration resulted in reduced visceral sensitivity, improved defecation parameters, decreased intestinal transport velocity, and reduced intestinal permeability in IBS-D mice. Furthermore, SSW promotes the secretion of colonic mucus by enhancing autophagy and inhibiting ER stress. SSW treatment caused remodeling of the gut microbiome by increasing the abundance of Blautia, Muribaculum and Ruminococcus torques group., Conclusion: SSW can improve intestinal barrier function by promoting autophagy and inhibiting ER stress, thus exerting a therapeutic effect on IBS-D., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Figures were created with BioRender software, biorender.com., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Growing evidence showed the capacity of (poly)phenols to exert a protective role on intestinal health. Nevertheless, the existing findings are still heterogeneous and the underlying mechanisms remain unclear. This study investigated the potential benefits of a red raspberry ( Rubus idaeus ) powder on the integrity of the intestinal barrier, focusing on its ability to mitigate the effects of tumor necrosis factor-α (TNF-α)-induced intestinal permeability. Human colorectal adenocarcinoma cells ( i.e. , Caco-2 cells) were used as a model to assess the impact of red raspberry on intestinal permeability, tight junction expression, and oxidative stress. The Caco-2 cells were differentiated into polarized monolayers and treated with interferon-γ (IFN-γ) (10 ng mL -1 ) for 24 hours, followed by exposure to TNF-α (10 ng mL -1 ) in the presence or absence of red raspberry extract (1-5 mg mL -1 ). The integrity of the intestinal monolayer was evaluated using transepithelial electrical resistance (TEER) and fluorescein isothiocyanate-dextran (FITC-D) efflux assay. Markers of intestinal permeability (claudin-1, occludin, and zonula occludens-1 (ZO-1)) and oxidative stress (8-hydroxy-2-deoxyguanosine (8-OHdG) and protein carbonyl) were assessed using ELISA kits. Treatment with red raspberry resulted in a significant counteraction of TEER value loss (41%; p < 0.01) and a notable reduction in the efflux of FITC-D (-2.5 times; p < 0.01). Additionally, red raspberry attenuated the levels of 8-OHdG (-48.8%; p < 0.01), mitigating the detrimental effects induced by TNF-α. Moreover, red raspberry positively influenced the expression of the integral membrane protein claudin-1 (+18%; p < 0.01), an essential component of tight junctions. These findings contribute to the growing understanding of the beneficial effects of red raspberry in the context of the intestinal barrier. The effect of red raspberry against TNF-α-induced intestinal permeability observed in our in vitro model suggests, for the first time, its potential as a dietary strategy to promote gastrointestinal health.

Anesthesia and surgery activate matrix metalloproteinase 9 (MMP9), leading to blood-brain barrier (BBB) disruption and postoperative delirium (POD)-like behavior, especially in the elderly. Aged mice received intraperitoneal injections of either the MMP9 inhibitor SB-3CT, melatonin, or solvent, and underwent laparotomy under 3 % sevoflurane anesthesia(anesthesia/surgery). Behavioral tests were performed 24 h pre- and post-operatively. Serum and cortical tissue levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) were measured using ELISA. Levels of PDGFRβ, MMP9, tight junction, Mfsd2a, caveolin-1, synaptophysin, and postsynaptic densin (PSD)-95 proteins in the prefrontal cortex were assayed using Western blotting. BBB permeability was assessed by detecting IgG in the prefrontal cortex and serum S100β levels. Anesthesia/surgery-induced peripheral inflammation activated MMP9, which in turn injured pericytes and tight junctions and increased transcytosis, thereby disrupting the BBB. Impaired BBB allowed the migration of peripheral inflammation into the central nervous system (CNS), thereby inducing neuroinflammation, synaptic dysfunction, and POD-like behaviors. However, MMP9 inhibition reduced pericyte and tight junction injury and transcytosis, thereby preserving BBB function and preventing the migration of peripheral inflammation into the CNS, thus attenuating synaptic dysfunction and POD-like behavior. In addition, to further validate the above findings, we showed that melatonin exerted similar effects through inhibition of MMP9. The present study shows that after anesthesia/surgery, inflammatory cytokines upregulation is involved in regulating BBB permeability in aged mice through activation of MMP9, suggesting that MMP9 may be a potential target for the prevention of POD., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive respiratory disorder characterized by poor prognosis, often presenting with acute exacerbation. The primary cause of death associated with IPF is acute exacerbation of IPF (AE-IPF). However, the pathophysiology of acute exacerbation has not been clearly elucidated yet. This study aims to investigate the underlying pathophysiological molecular mechanism in a mouse AE-PF model. C57BL/6J mice were intratracheally administered bleomycin (BLM, 5 mg/kg) to induce pulmonary fibrosis. After 14 days, lipopolysaccharide (LPS, 2 mg/kg) was injected via the trachea route. Histological assessments, including H&E and Masson staining, as well as inflammatory indicators, were included to evaluate the induction of AE-PF by BLM and LPS in mice. Transcriptomic profiling of pulmonary tissues identified CSF3 as one of the top 10 upregulated DEGs in AE-PF mice. Indeed, administration of exogenous CSF3 protein exacerbated AE-PF in mice. Mechanistically, CSF3 disrupted alveolar epithelial barrier integrity and permeability by regulating specialized cell adhesion complexes such as tight junctions (TJs) and adherens junctions (AJs) via PI3K/p-Akt/Snail pathway, contributing to the aggravation of AE-PF in mice. Moreover, the discovery of elevated sera CSF3 indicated a notable increase in IPF patients during the exacerbation of the disease. Pearson correlation analysis in IPF patients revealed significant positive associations between CSF3 levels and KL-6 levels, LDH levels, CRP levels, respectively. These results provide mechanistic insights into the role of CSF3 in exacerbating of lung fibrotic disease and indicate monitoring CSF3 levels may aid in early clinical decisions for alternative therapy in the management of rapidly progressing IPF., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this study, we investigated the effect of monobutyrin (MB) on the gut microbiota and intestinal health of weaned mice. MB was administered via gavage to 21-day-old weaned mice. Samples of small intestinal and ileal contents were collected on day 1, day 7, and day 21 post-administration. Seven days of MB administration enhanced the mucin layer and morphological structure of the intestine and the integrity of the intestinal brush border. Both MB and sodium butyrate (SB) accelerated tight junction development. Compared to SB, MB modulated intestinal T cells in a distinct manner. MB increased the ratio of Treg cells in the small intestine upon the cessation of weaning. After 21 days of MB administration, enhancement of the villus structure of the ileum was observed. MB increased the proportion of Th17 cells in the ileum. MB facilitated the transition of the small intestinal microbiota toward an adult microbial community structure and enhanced the complexity of the microbial community structure. An increase in Th17 cells enhanced intestinal barrier function. The regulatory effect of MB on Th17 cells may occur through the intestinal microbiota. Therefore, MB can potentially be used to promote intestinal barrier function, especially for weaning animals, with promising application prospects.

Background: Sepsis is one of the most common clinical diseases, which is characterized by a serious and uncontrollable inflammatory response. LPS-induced inflammation is a critical pathological event in sepsis, but the underlying mechanism has not yet been fully elucidated., Methods: The animal model was established for two batches. In the first batch of experiments, Adult C57BL/6J mice were randomly divided into control group and LPS (5 mg/kg, i.p.)group . In the second batch of experiments, mice were randomly divided into control group, LPS group, and LPS+VX765(10 mg/kg, i.p., an inhibitor of NLRP3 inflammasome) group. After 24 hours, mice were anesthetized with isoflurane, blood and intestinal tissue were collected for tissue immunohistochemistry, Western blot analysis and ELISA assays., Results: The C57BL/6J mice injected with LPS for twenty-four hours could exhibit severe inflammatory reaction including an increased IL-1β, IL-18 in serum and activation of NLRP3 inflammasome in intestine. The injection of VX765 could reverse these effects induced by LPS. These results indicated that the increased level of IL-1β and IL-18 in serum induced by LPS is related to the increased intestinal permeability and activation of NLRP3 inflammasome. In the second batch of experiments, results of western blot and immunohistochemistry showed that Slit2 and Robo4 were significant decreased in intestine of LPS group, while the expression of VEGF was significant increased. Meanwhile, the protein level of tight junction protein ZO-1, occludin, and claudin-5 were significantly lower than in control group, which could also be reversed by VX765 injection., Conclusions: In this study, we revealed that Slit2-Robo4 signaling pathway and tight junction in intestine may be involved in LPS-induced inflammation in mice, which may account for the molecular mechanism of sepsis., (© 2024. The Author(s).)

Real-time and non-invasive assessment of tissue health is crucial for maximizing the potential of microphysiological systems (MPS) for drug-induced nephrotoxicity screening. Although impedance has been widely considered as a measure of the barrier function, it has not been incorporated to detect cell detachment in MPS with top and bottom microfluidic channels separated by a porous membrane. During cell delamination from the porous membrane, the resistance between both channels decreases, while capacitance increases, allowing the detection of such detachment. Previously reported concepts have solely attributed the decrease in the resistance to the distortion of the barrier function, ignoring the resistance and capacitance changes due to cell detachment. Here, we report a two-channel MPS with integrated indium tin oxide (ITO) electrodes capable of measuring impedance in real time. The trans-epithelial electrical resistance (TEER) and tissue reactance (capacitance) were extracted from the impedance profiles. We attributed the anomalous initial increase observed in TEER, upon cisplatin administration, to the distortion of tight junctions. Cell detachment was captured by sudden jumps in capacitance. TEER profiles illuminated the effects of cisplatin and cimetidine treatments in a dose-dependent and polarity-dependent manner. The correspondence between TEER and barrier function was validated for a continuous tissue using the capacitance profiles. These results demonstrate that capacitance can be used as a real-time and non-invasive indicator of confluence and will support the accuracy of the drug-induced cytotoxicity assessed by TEER profiles in the two-channel MPS for the barrier function of a cell monolayer.

Pesticides and plastics bring convenience to agriculture and life, but also bring residual pollution in the environment. Emamectin benzoate (EMB) is the most popular pesticide at present. The harm of microplastics (MPs) to water and aquatic organisms is gradually increasing, and the possibility that it appears synchronously with various pesticides increases. However, the damage of EMB and MPs to the carp midgut and its mechanism have not been clarified. Therefore, based on the EMB or/and MPs exposure models, this study explored the mechanism of midgut injury through transcriptomics, immunofluorescence, western blot methods, and so on. Studies in vivo and in vitro showed that EMB or MPs exposure caused cilia shortening, lysosome damage, and ROS overproduction, which led to Fe 2+ content increase, GSH/GSSG system disorder, lipid peroxidation, and ferroptosis. This process further led to the down-regulation of Cx43, Occludin, Claudin, and ZO-1, which further caused barrier damage, immune-related genes (immunoglobulin, IFN-γ) decrease and inflammation-related genes (TNF-α, IL-1β) increase. Combined exposure was more significant than that of single exposure, and the addition of EN6 and NAC proved that lysosome/ROS/ferroptosis regulated these midgut damages. In conclusion, EMB or/and MPs exposure induce tight junction disorder, immune disorder and inflammation in carp midgut through the lysosome/ROS/ferroptosis pathway., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Microplastics, which are tiny plastic particles less than 5 mm in diameter, are widely present in the environment, have become a serious threat to aquatic life and human health, potentially causing ecosystem disorders and health problems. The present study aimed to investigate the effects of microplastics, specifically microplastics-polystyrene (MPs-PS), on the structural integrity, gene expression related to tight junctions, and gut microbiota in mice. A total of 24 Kunming mice aged 30 days were randomly assigned into four groups: control male (CM), control female (CF), PS-exposed male (PSM), and PS-exposed female (PSF)(n = 6). There were significant differences in villus height, width, intestinal surface area, and villus height to crypt depth ratio (V/C) between the PS group and the control group(C) (p <0.05). Gene expression analysis demonstrated the downregulation of Claudin-1, Claudin-2, Claudin-15, and Occludin, in both duodenum and jejunum of the PS group (p < 0.05). Analysis of microbial species using 16S rRNA sequencing indicated decreased diversity in the PSF group, as well as reduced diversity in the PSM group at various taxonomic levels. Beta diversity analysis showed a significant difference in gut microbiota distribution between the PS-exposed and C groups (R2 = 0.113, p<0.01), with this difference being more pronounced among females exposed to MPs-PS. KEGG analysis revealed enrichment of differential microbiota mainly involved in seven signaling pathways, such as nucleotide metabolism(p<0.05). The relative abundance ratio of transcriptional pathways was significantly increased for the PSF group (p<0.01), while excretory system pathways were for PSM group(p<0.05). Overall findings suggest that MPs-PS exhibit a notable sex-dependent impact on mouse gut microbiota, with a stronger effect observed among females; reduced expression of tight junction genes may be associated with dysbiosis, particularly elevated levels of Prevotellaceae., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Su et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Acute respiratory distress syndrome (ARDS) is an acute and severe clinical complication lacking effective therapeutic interventions. The disruption of the lung epithelial barrier plays a crucial role in ARDS pathogenesis. Recent studies have proposed the involvement of abnormal mitochondrial dynamics mediated by dynamin-related protein 1 (Drp1) in the mechanism of impaired epithelial barrier in ARDS. Hydrogen is an anti-oxidative stress molecule that regulates mitochondrial function via multiple signaling pathways. Our previous study confirmed that hydrogen modulated oxidative stress and attenuated acute pulmonary edema in ARDS by upregulating thioredoxin 1 (Trx1) expression, but the exact mechanism remains unclear. This study aimed to investigate the effects of hydrogen on mitochondrial dynamics both in vivo and in vitro. Our study revealed that hydrogen inhibited lipopolysaccharide (LPS)-induced phosphorylation of Drp1 (at Ser616), suppressed Drp1-mediated mitochondrial fission, alleviated epithelial tight junction damage and cell apoptosis, and improved the integrity of the epithelial barrier. This process was associated with the upregulation of Trx1 in lung epithelial tissues of ARDS mice by hydrogen. In addition, hydrogen treatment reduced the production of reactive oxygen species in LPS-induced airway epithelial cells (AECs) and increased the mitochondrial membrane potential, indicating that the mitochondrial dysfunction was restored. Then, the expression of tight junction proteins occludin and zonula occludens 1 was upregulated, and apoptosis in AECs was alleviated. Remarkably, the protective effects of hydrogen on the mitochondrial and epithelial barrier were eliminated after applying the Trx1 inhibitor PX-12. The results showed that hydrogen significantly inhibited the cell apoptosis and the disruption of epithelial tight junctions, maintaining the integrity of the epithelial barrier in mice of ARDS. This might be related to the inhibition of Drp1-mediated mitochondrial fission through the Trx1 pathway. The findings of this study provided a new theoretical basis for the application of hydrogen in the clinical treatment of ARDS., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Gut epithelial barrier disruption is commonly observed in Western diseases like diabetes and inflammatory bowel disease (IBD). Enhanced epithelial permeability triggers inflammatory responses and gut microbiota dysbiosis. Reduced bacterial diversity in IBD affects gut microbiota metabolism, altering microbial products such as secondary bile acids (BAs), which potentially play a role in gut barrier regulation and immunity. Dietary fibers such as pectin may substitute effects of these BAs. The study examines transepithelial electrical resistance of gut epithelial T84 cells and the gene expression of tight junctions after exposure to (un)sulfated secondary BAs. This is compared to the impact of the dietary fiber pectin with different degrees of methylation (DM) and blockiness (DB), with disruption induced by calcium ionophore A23187 under both normal and hyperglycemic conditions. Unsulfated lithocholic acid (LCA) and deoxycholic acid (DCA) show a stronger rescuing effect, particularly evident under 20 mM glucose levels. DM19 with high DB (HB) and DM43HB pectin exhibit rescuing effects under both glucose conditions. Notably, DM19HB and DM43HB display higher rescue effects under 20 mM glucose compared to 5 mM glucose. The study demonstrates that specific pectins such as DM19HB and DM43HB may serve as alternatives for preventing barrier disruption in the case of disturbed DCA metabolism., (© 2024 The Author(s). Molecular Nutrition & Food Research published by Wiley‐VCH GmbH.)

Objective: To investigate the effect of honokiol (HON) and the role of high-mobility group protein B1 (HMGB1) on the pathogenesis of severe acute pancreatitis (SAP)., Methods: Thirty mice were numbered according to weight, and randomly divided into 5 groups using a random number table, including control, SAP, SAP and normal saline (SAP+NS), SAP and ethyl pyruvate (SAP+EP), or SAP+HON groups, 6 mice in each group. Samples of pancreas, intestine, and blood were collected 12 h after SAP model induction for examination of pathologic changes, immune function alterations by enzyme linked immunosorbent assay (ELISA), and Western blot. In vitro experiments, macrophages were divided into 5 groups, the control, lipopolysaccharide (LPS), LPS+DMSO (DMSO), LPS+anti-HMGB1 monoclonal antibody (mAb), and LPS+ HON groups. The tight connection level was determined by transmission electron microscopy and fluorescein isothiocyanate-labeled. The location and acetylation of HMGB1 were measured by Western blot. Finally, pyridone 6 and silencing signal transducer and activator of the transcription 1 (siSTAT1) combined with honokiol were added to determine whether the Janus kinase (JAK)/ STAT1 participated in the regulation of honokiol on HMGB1. The protein expression levels of HMGB1, JAK, and STAT1 were detected using Western blot., Results: Mice with SAP had inflammatory injury in the pancreas, bleeding of intestinal tissues, and cells with disrupted histology. Mice in the SAP+HON group had significantly fewer pathological changes. Mice with SAP also had significant increases in the serum levels of amylase, lipase, HMGB1, tumor necrosis factor- α, interleukin-6, diamine oxidase, endotoxin-1, and procalcitonin. Mice in the SAP+HON group did not show these abnormalities (P<0.01). Studies of Caco-2 cells indicated that LPS increased the levels of occludin and claudin-1 as well as tight junction permeability, decreased the levels of junctional adhesion molecule C, and elevated intercellular permeability (P<0.01). HON treatment blocked these effects. Studies of macrophages indicated that LPS led to low nuclear levels of HMGB1, however, HON treatment increased the nuclear level of HMGB1 (P<0.01). HON treatment also inhibited the expressions of JAK1, JAK2, and STAT1 (P<0.01) and increased the acetylation of HMGB1 (P<0.05)., Conclusion: HON prevented intestinal barrier dysfunction in SAP by inhibiting HMGB1 acetylation and JAK/STAT1 pathway., (© 2023. The Chinese Journal of Integrated Traditional and Western Medicine Press and Springer-Verlag GmbH Germany, part of Springer Nature.)

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

Imperatorin (IMP) is the main bioactive furanocoumarin of Angelicae dahuricae radix, which is a well-known traditional Chinese medicine. The purpose of this study was to elucidate the role of IMP in promoting absorption and the possible mechanism on the compatible drugs of Angelicae dahuricae radix. The influence of IMP on drugs' intestinal absorption was conducted by the Caco-2 cell model. The mechanism was studied by investigating the transcellular transport mode of IMP and its influence on P-glycoprotein (P-gp)-mediated efflux, protein expression of P-gp and tight junction, and cell membrane potential. The result showed IMP promoted the uptake of osthole, daidzein, ferulic acid, and puerarin and improved the transport of ferulic acid and puerarin in Caco-2 cells. The absorption-promoting mechanism of IMP might involve the reduction of the cell membrane potential, decrease of P-gp-mediated drug efflux and inhibition of the P-gp expression level in the cellular pathway, and the loosening of the tight junction protein by the downregulation of the expression levels of occludin and claudin-1 in the paracellular pathway. This study provides new insights into the understanding of the improved bioavailability of Angelicae dahuricae radix with its compatible drugs., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Royal Pharmaceutical Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Diabetic retinopathy (DR) is a secondary complication of diabetes that can lead to visual impairment and blindness. The retinal pigment epithelium (RPE) is a monolayer of pigment cells that forms the blood-retinal barrier (BRB) via tight junction (TJ) proteins and plays a crucial role in the physiological function of the retina. Hyperglycemia induces RPE death and BRB breakdown, which accelerates the process of DR. Curcumin, an active extract of Curcuma longa , has anti-inflammatory, antioxidant, antiapoptotic, and neuroprotective properties. However, the effect of Curcumin on the BRB under high glucose conditions remains unknown. This study aimed to investigate the protective effects of Curcumin on RPE physiology in vitro and in vivo . Curcumin significantly alleviated cell viability inhibition under high glucose conditions. Moreover, high glucose reduced extracellular signal-regulated kinase and Akt pathways activation to diminish RPE cell growth but reversed by Curcumin treatment. Curcumin protected not only TJ integrity but also retinoid regeneration through TJ proteins and isomerase modulation in diabetic retina. Furthermore, Curcumin decreased the expression of angiogenic factor to inhibit retinal neovascularization. Finally, Curcumin treatment markedly reduced apoptosis during hyperglycemia. In conclusion, Curcumin can alleviate the progression of DR by promoting RPE survival, TJ integrity, retinoid isomerase activity, RPE senescence inhibition, and neovascularization. Therefore, Curcumin exhibits high potential for use as a therapeutic agent for early DR., (Copyright © 2024 Copyright: © 2024 Journal of Physiological Investigation.)

Allergic inflammation, which is the pathogenesis of allergic rhinitis and asthma, is associated with disruption of the airway epithelial barrier due to the effects of type 2 inflammatory cytokines, i.e. interleukin-4 and interleukin-13 (IL-4/13). The anti-allergic inflammatory effect of β-eudesmol (BE) on the tight junction (TJ) of the airway epithelium has not previously been reported. Herein, the barrier protective effect of BE was determined by measurement of transepithelial electrical resistance and by paracellular permeability assay in an IL-4/13-treated 16HBE14o- monolayer. Pre-treatment of BE concentration- and time- dependently inhibited IL-4/13-induced TJ barrier disruption, with the most significant effect observed at 20 μM. Cytotoxicity analyses showed that BE, either alone or in combination with IL-4/13, had no effect on cell viability. Western blot and immunofluorescence analyses showed that BE inhibited IL-4/13-induced mislocalization of TJ components, including occludin and zonula occludens-1 (ZO-1), without affecting the expression of these two proteins. In addition, the mechanism of the TJ-protective effect of BE was mediated by inhibition of IL-4/13-induced STAT6 phosphorylation, in which BE might serve as an antagonist of cytokine receptors. In silico molecular docking analysis demonstrated that BE potentially interacted with the site I pocket of the type 2 IL-4 receptor, likely at Asn-126 and Tyr-127 amino acid residues. It can therefore be concluded that BE is able to prevent IL-4/13-induced TJ disassembly by interfering with cytokine-receptor interaction, leading to suppression of STAT6-induced mislocalization of occludin and ZO-1. BE is a promising candidate for a therapeutic intervention for inflammatory airway epithelial disorders driven by IL-4/13., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Tharabenjasin et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Laurus nobilis L. (LNL) belongs to the evergreen Lauraceae family. It is native to the Mediterranean and widely distributed in the southern United States, Europe, and the Middle East. LNL is rich in active ingredients of the sesquiterpene lactone series and has been reported to have antioxidant, anti-inflammatory, and anticancer effects. And parthenolide, known as a sesquiterpene lactone-based compound, inhibits the activation of lipopolysaccharide-binding protein (LBP), which is a major trigger for leaky gut syndrome. However, the effectiveness of LNL in improving the state of increased intestinal permeability has not yet been reported. Therefore, we demonstrated the efficacy of LNL, which is known to be rich in parthenolide, in improving intestinal permeability induced by IL-13. We investigated the improvement in permeability and analyzed major tight junction proteins (TJs), permeability-related mechanisms, weight and disease activity indices, and corresponding cytokine mechanisms. LNL maintained TJs homeostasis and clinical improvement by reducing increased claudin-2 through the inhibition of IL-13/STAT6 activation in TJ-damaged conditions. These results are expected to be effective in preventing leaky gut syndrome through the TJ balance and to further improve intestinal-related diseases, such as inflammatory bowel disease.