Evaluation of serum zonulin and occludin levels in obsessive-compulsive disorder and the effect of major depressive disorder comorbidity.

Objective: The aim of this study is to determine whether the levels of zonulin and occludin, tight junctions (TJ) proteins in the intestinal epithelium, will differ between obsessive compulsive disorder (OCD) patients and healthy controls. We also intended to investigate whether these would vary in OCD patients with and without major depressive disorder (MDD) comorbidity and in comparison with healthy controls. Methods: Sixty patients diagnosed with OCD and 30 healthy controls were included in the study. The cases were administered the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and the Hamilton Depression Rating Scale (HDRS). The patients were divided into two subgroups based on their HDRS scores and presence of MDD comorbidity. Zonulin and occludin levels were measured using the ELISA method. The research was carried out between April 2021 and October 2021. Results: Zonulin and occludin levels were significantly higher in the OCD patient group than in the control group (p<0.001). The levels of both were also significantly higher in the OCD patients with MDD comorbidity (OCD+MDD) compared to those without MDD (OCD-MDD) (p<0.001). Zonulin and occludin levels also rose significantly as disease severity increased in the OCD patient group (respectively; p<0.001, p=0.001). The levels of both increased in line with the severity of depression based on HDRS scores in the OCD+MDD group (p<0.001). A positive correlation was determined between the duration of OCD and zonulin and occludin levels. Evaluation of the entire OCD group revealed a moderate positive correlation between Y-BOCS and HDRS scores and zonulin and occludin. Conclusions: Zonulin and occludin levels in this research were significantly higher in the patients with OCD than in the healthy controls. That elevation was positively correlated with disease duration and severity, and the increase was significantly more pronounced in OCD with MDD comorbidity. These findings point to a possible disorder in the intestinal barrier and blood-brain barrier in OCD patients.

Role of tight junction proteins in shaping the immune milieu of malignancies.

INTRODUCTION: Tight junctions (TJs) and their constituent proteins play pivotal roles in cellular physiology and anatomy by establishing functional boundaries within and between neighboring cells. While the involvement of TJ proteins, such as claudins, in cancer is extensively studied, studies highlighting their interaction with immune system are still meager. Studies indicate that alterations in cytokines and immune cell populations can affect TJ proteins, compromising TJ barrier function and exacerbating pro-inflammatory conditions, potentially leading to epithelial cell malignancy. Disrupted TJs in established tumors may foster a pro-tumor immune microenvironment, facilitating tumor progression, invasion, epithelial-to-mesenchymal transition and metastasis. Although previous literature contains many studies describing the involvement of TJs in pathogenesis of malignancies their role in modulating the immune microenvironment of tumors is just beginning to be unleashed. AREAS COVERED: This article for the first time attempts to discern the importance of interaction between TJs and immune microenvironment in malignancies. To achieve the above aim a thorough search of databases like PubMed and Google Scholar was conducted to identify the recent and relevant articles on the topic. EXPERT OPINION: Breaking the vicious cycle of dysbiosis/infections/chemical/carcinogen-induced inflammation-TJ remodeling-malignancy-TJ dysregulation-more inflammation can be used as a strategy to complement the effect of immunotherapies in various malignancies.

The Basic Requirement of Tight Junction Proteins in Blood-Brain Barrier Function and Their Role in Pathologies.

This review addresses the role of tight junction proteins at the blood-brain barrier (BBB). Their expression is described, and their role in physiological and pathological processes at the BBB is discussed. Based on this, new approaches are depicted for paracellular drug delivery and diagnostics in the treatment of cerebral diseases. Recent data provide convincing evidence that, in addition to its impairment in the course of diseases, the BBB could be involved in the aetiology of CNS disorders. Further progress will be expected based on new insights in tight junction protein structure and in their involvement in signalling pathways.

MITOCHONDRIAL ANTIVIRAL PATHWAYS CONTROL ANTI-HIV RESPONSES AND ISCHEMIC STROKE OUTCOMES VIA THE RIG-1 SIGNALING AND INNATE IMMUNITY MECHANISMS.

Occludin (ocln) is one of the main regulatory cells of the blood-brain barrier (BBB). Ocln silencing resulted in alterations of the gene expression signatures of a variety of genes of the innate immunity system, including IFN-stimulated genes (ISGs) and the antiviral retinoic acid-inducible gene-1 (RIG-1) signaling pathway, which functions as a regulator of the cytoplasmic sensors upstream of the mitochondrial antiviral signaling protein (MAVS). Indeed, we observed dysfunctional mitochondrial bioenergetics, dynamics, and autophagy in our system. Alterations of mitochondrial bioenergetics and innate immune protection translated into worsened ischemic stroke outcomes in EcoHIV-infected ocln deficient mice. Overall, these results allow for a better understanding of the molecular mechanisms of viral infection in the brain and describe a previously unrecognized role of ocln as a key factor in the control of innate immune responses and mitochondrial dynamics, which affect cerebral vascular diseases such as ischemic stroke.

A short guide to the tight junction.

Tight junctions (TJs) are specialized regions of contact between cells of epithelial and endothelial tissues that form selective semipermeable paracellular barriers that establish and maintain body compartments with different fluid compositions. As such, the formation of TJs represents a critical step in metazoan evolution, allowing the formation of multicompartmental organisms and true, barrier-forming epithelia and endothelia. In the six decades that have passed since the first observations of TJs by transmission electron microscopy, much progress has been made in understanding the structure, function, molecular composition and regulation of TJs. The goal of this Perspective is to highlight the key concepts that have emerged through this research and the future challenges that lie ahead for the field.

Leaky gut and inflammatory biomarkers in a medication overuse headache model in male rats.

Background/aim: Medication overuse is common among chronic migraine patients and nonsteroidal antiinflammatory drugs (NSAIDs) are the most frequently overused drugs. The pathophysiological mechanisms underlying medication overuse headache (MOH) are not completely understood. Intestinal hyperpermeability and leaky gut are reported in patients using NSAIDs. The aim of the study is to investigate the role of leaky gut and inflammation in an MOH model MOH model in male rats. Methods: The study was conducted in male Sprague Dawley rats. There were two experimental groups. The first group was the chronic NSAID group in which the rats received mefenamic acid (n = 8) for four weeks intraperitoneally (ip) and the second group was the vehicle group (n = 8) that received 5% dimethyl sulfoxide+sesame oil (ip) for 4 weeks. We assessed spontaneous pain-like behavior, periorbital mechanical withdrawal thresholds, and anxiety-like behavior using an elevated plus maze test. After behavioral testing, serum levels of occludin and lipopolysaccharide-binding protein (LBP) and brain levels of IL-17, IL-6, and high mobility group box 1 protein (HMGB1) were evaluated with ELISA.Results: Serum LBP and occludin levels and brain IL-17 and HMGB1 levels were significantly elevated in the chronic NSAID group compared to its vehicle (p = 0.006, p = 0.016, p = 0.016 and p = 0.016 respectively) while brain IL-6 levels were comparable (p = 0.67) between the groups. The chronic NSAID group showed pain-like and anxiety-like behavior in behavioral tests. Brain IL-17 level was positively correlated with number of head shakes (r = 0.64, p = 0.045), brain IL-6 level was negatively correlated with periorbital mechanical withdrawal thresholds (r = -0.71, p = 0.049), and serum occludin level was positively correlated with grooming duration (r = 0.73, p = 0.032) in chronic NSAID group. Conclusion: Elevated serum occludin and LBP levels and brain IL-17 and HMGB1 levels indicate a possible role of leaky gut and inflammation in an MOH model in male rats. Additionally, a significant correlation between pain behavior and markers of inflammation and intestinal hyperpermeability, supports the role of inflammation and leaky gut in MOH pathophysiology.

The correlation between fecal microbiota profiles and intracellular junction genes expression in young Iranian patients with celiac disease.

Celiac disease (CD) is characterized by the disruption of the intestinal barrier integrity and alterations in the microbiota composition. This study aimed to evaluate the changes in the fecal microbiota profile and mRNA expressions of intracellular junction-related genes in pediatric patients with CD compared to healthy controls (HCs). Thirty treated CD patients, 10 active CD, and 40 HCs were recruited. Peripheral blood (PB) and fecal samples were collected. Microbiota analysis was performed using quantitative real-time PCR (qPCR) test. The mRNA expressions of ZO-1, occludin, ß-catenin, E-cadherin, and COX-2 were also evaluated. In active and treated CD patients, the PB expression levels of ZO-1 (p = 0.04 and 0.002, respectively) and ß-catenin (p = 0.006 and 0.02, respectively) were lower than in HCs. PB Occludin's level was upregulated in both active and treated CD patients compared to HCs (p = 0.04 and 0.02, respectively). However, PB E-cadherin and COX-2 expression levels and fecal mRNA expressions of ZO-1, occludin, and COX-2 did not differ significantly between cases and HCs (P˃0.05). Active CD patients had a higher relative abundance of the Firmicutes (p = 0.04) and Actinobacteria (p = 0.03) phyla compared to treated subjects. The relative abundance of Veillonella (p = 0.04) and Staphylococcus (p = 0.01) genera was lower in active patients in comparison to HCs. Researchers should explore the precise impact of the gut microbiome on the molecules and mechanisms involved in intestinal damage of CD. Special attention should be given to Bifidobacteria and Enterobacteriaceae, as they have shown a significant correlation with the expression of tight junction-related genes.

Da-Cheng-Qi decoction improves severe acute pancreatitis capillary leakage syndrome by regulating tight junction-associated proteins.

Background and aims: To investigate mechanisms underlying the effects of Da-Cheng-Qi decoction (DCQD) on severe acute pancreatitis (SAP) capillary leakage syndrome. Methods: In this study, a SAP rat model was established using retrograde perfusion of 5% sodium taurocholate into the biliopancreatic duct. The study included three randomized groups: control, SAP (modeling), and DCQD (via gavage at 2 h pre-modeling and 2 and 4 h post-modeling). HPLC was used to analyzed major components of DCQD. Pathological changes and capillary permeability in the rat pancreatic tissues were examined. mRNA levels of claudin 5, occludin, zonula occludin-1 (ZO-1), and junctional adhesion molecules (JAM-C) were assessed using qRT-PCR. Tight junction-associated protein expression was evaluated using immunofluorescence and Western blot analyses. Human umbilical vein endothelial cells (HUVECs) were used to investigate the mechanism m of DCQD. Results: Serum levels of amylase, TNF-α, IL-1ß, IL-2, and IL-6 were higher in the SAP group compared to the DCQD group (p < 0.05). DCQD treatment significantly attenuated rat pancreas damage (p < 0.05) and reduced tissue capillary permeability compared to the SAP group (p < 0.05). Claudin 5, occludin, and ZO-1 expression in the rat tissues was upregulated, but JAM-C was downregulated by DCQD treatment (p < 0.05). HUVEC permeability was improved by DCQD in a dose-time-dependent manner compared to the SAP group (p < 0.05). DCQD also upregulated claudin 5, occludin, and ZO-1 expression in vitro (p < 0.05). Conclusion: DCQD can improve capillary permeability in both in vivo and in vitro models of SAP by upregulating expression of claudin 5, occludin, and ZO-1, but not JAM-C.

Semaphorin 7A impairs barrier function in cultured human corneal epithelial cells in a manner dependent on nuclear factor-kappa B.

AIM: To evaluate the role of semaphorin 7A (Sema7A) and its associated regulatory mechanisms in modulating the barrier function of cultured human corneal epithelial cells (HCEs). METHODS: Barrier models of HCEs were treated with recombinant human Sema7A at concentrations of 0, 125, 250, or 500 ng/mL for 24, 48, or 72h in vitro. Transepithelial electrical resistance (TEER) as well as Dextran-fluorescein isothiocyanate (FITC) permeability assays were conducted to assess barrier function. To quantify tight junctions (TJs) such as occludin and zonula occludens-1 (ZO-1) at the mRNA level, reverse transcription-polymerase chain reaction (RT-PCR) analysis was performed. Immunoblotting was used to examine the activity of the nuclear factor-kappa B (NF-κB) signaling pathway and the production of TJs proteins. Immunofluorescence analyses were employed to localize the TJs. Enzyme-linked immunosorbent assay (ELISA) and RT-PCR were utilized to observe changes in interleukin (IL)-1ß levels. To investigate the role of NF-κB signaling activation and IL-1ß in Sema7A's anti-barrier mechanism, we employed 0.1 µmol/L IκB kinase 2 (IKK2) inhibitor IV or 500 ng/mL IL-1 receptor (IL-1R) antagonist. RESULTS: Treatment with Sema7A resulted in decreased TEER and increased permeability of Dextran-FITC in HCEs through down-regulating mRNA and protein levels of TJs in a time- and dose-dependent manner, as well as altering the localization of TJs. Furthermore, Sema7A stimulated the activation of inhibitor of kappa B alpha (IκBα) and expression of IL-1ß. The anti-barrier function of Sema7A was significantly suppressed by treatment with IKK2 inhibitor IV or IL-1R antagonists. CONCLUSION: Sema7A disrupts barrier function through its influence on NF-κB-mediated expression of TJ proteins, as well as the expression of IL-1ß. These findings suggest that Sema7A could be a potential therapeutic target for the diseases in corneal epithelium.

A novel in vitro high-content imaging assay for the prediction of drug-induced lung toxicity.

The development of inhaled drugs for respiratory diseases is frequently impacted by lung pathology in non-clinical safety studies. To enable design of novel candidate drugs with the right safety profile, predictive in vitro lung toxicity assays are required that can be applied during drug discovery for early hazard identification and mitigation. Here, we describe a novel high-content imaging-based screening assay that allows for quantification of the tight junction protein occludin in A549 cells, as a model for lung epithelial barrier integrity. We assessed a set of compounds with a known lung safety profile, defined by clinical safety or non-clinical in vivo toxicology data, and were able to correctly identify 9 of 10 compounds with a respiratory safety risk and 9 of 9 compounds without a respiratory safety risk (90% sensitivity, 100% specificity). The assay was sensitive at relevant compound concentrations to influence medicinal chemistry optimization programs and, with an accessible cell model in a 96-well plate format, short protocol and application of automated imaging analysis algorithms, this assay can be readily integrated in routine discovery safety screening to identify and mitigate respiratory toxicity early during drug discovery. Interestingly, when we applied physiologically-based pharmacokinetic (PBPK) modelling to predict epithelial lining fluid exposures of the respiratory tract after inhalation, we found a robust correlation between in vitro occludin assay data and lung pathology in vivo, suggesting the assay can inform translational risk assessment for inhaled small molecules.

Occludin and collagen IV degradation mediated by the T9SS effector SspA contributes to blood-brain barrier damage in ducks during Riemerella anatipestifer infection.

Riemerella anatipestifer infection is characterized by meningitis with neurological symptoms in ducklings and has adversely affected the poultry industry. R. anatipestifer strains can invade the duck brain to cause meningitis and neurological symptoms, but the underlying mechanism remains unknown. In this study, we showed that obvious clinical symptoms, an increase in blood‒brain barrier (BBB) permeability, and the accumulation of inflammatory cytokines occurred after intravenous infection with the Yb2 strain but not the mutant strain Yb2ΔsspA, indicating that Yb2 infection can lead to cerebrovascular dysfunction and that the type IX secretion system (T9SS) effector SspA plays a critical role in this pathological process. In addition, we showed that Yb2 infection led to rapid degradation of occludin (a tight junction protein) and collagen IV (a basement membrane protein), which contributed to endothelial barrier disruption. The interaction between SspA and occludin was confirmed by coimmunoprecipitation. Furthermore, we found that SspA was the main enzyme mediating occludin and collagen IV degradation. These data indicate that R. anatipestifer SspA mediates occludin and collagen IV degradation, which functions in BBB disruption in R. anatipestifer-infected ducks. These findings establish the molecular mechanisms by which R. anatipestifer targets duckling endothelial cell junctions and provide new perspectives for the treatment and prevention of R. anatipestifer infection.

Atorvastatin-induced intracerebral hemorrhage is inhibited by berberine in zebrafish.

Intracerebral hemorrhage (ICH), for which there are currently no effective preventive or treatment methods, has a very high fatality rate. Statins, such as atorvastatin (ATV), are the first-line drugs for regulating blood lipids and treating hyperlipidemia-related cardiovascular diseases. However, ATV-associated ICH has been reported, although its incidence is rare. In this study, we aimed to investigate the protective action and mechanisms of berberine (BBR) against ATV-induced brain hemorrhage. We established an ICH model in zebrafish induced by ATV (2 µM) and demonstrated the effects of BBR (10, 50, and 100 µM) on ICH via protecting the vascular network using hemocyte staining and three transgenic zebrafish. BBR was found to reduce brain inflammation and locomotion injury in ICH-zebrafish. Mechanism research showed that ATV increased the levels of VE-cadherin and occludin proteins but disturbed their localization at the cell membrane by abnormal phosphorylation, which decreased the number of intercellular junctions between vascular endothelial cells (VECs), disrupting the integrity of vascular walls. BBR reversed the effects of ATV by promoting autophagic degradation of phosphorylated VE-cadherin and occludin in ATV-induced VECs examined by co-immunoprecipitation (co-IP). These findings provide crucial insights into understanding the BBR mechanisms involved in the maintenance of vascular integrity and in mitigating adverse reactions to ATV.

The FAK/occludin/ZO-1 complex is critical for cadmium-induced testicular damage by disruption of the integrity of the blood-testis barrier in chickens.

Cadmium (Cd) is a well-known testis toxicant. The blood-testis barrier (BTB) is a crucial component of the testis. Cd can disrupt the integrity of the BTB and reproductive function. However, the mechanism of Cd-induced disruption of BTB and testicular damage has not been fully elucidated. Here, our study investigates the effects of Cd on BTB integrity and testicular dysfunction. 80 (aged 1 day) Hy-Line white variety chickens were randomly designed into 4 groups and treated for 90 days, as follows: control group (essential diet), 35 Cd, 70 Cd and 140 Cd groups (35, 70 and 140 mg/kg Cd). The results found that Cd exposure diminished volume of the testes and induced histopathological lesions in the testes. Exposure to Cd induced an inflammatory response, disrupted the structure and function of the FAK/occludin/ZO-1 protein complex and disrupted the tight junction and adherens junction in the BTB. In addition, Cd exposure reduced the expression of steroid-related proteins and inhibited testosterone synthesis. Taken together, these data elucidate that Cd disrupts the integrity of the BTB and further inhibits spermatogenesis by dissociating the FAK/occludin/ZO-1 complex, which provides a basis for further investigation into the mechanisms of Cd-induced impairment of male reproductive function and pharmacological protection.

Streptococcus pneumoniae extracellular vesicles aggravate alveolar epithelial barrier disruption via autophagic degradation of OCLN (occludin).

Streptococcus pneumoniae (S. pneumoniae) represents a major human bacterial pathogen leading to high morbidity and mortality in children and the elderly. Recent research emphasizes the role of extracellular vesicles (EVs) in bacterial pathogenicity. However, the contribution of S. pneumoniae EVs (pEVs) to host-microbe interactions has remained unclear. Here, we observed that S. pneumoniae infections in mice led to severe lung injuries and alveolar epithelial barrier (AEB) dysfunction. Infections of S. pneumoniae reduced the protein expression of tight junction protein OCLN (occludin) and activated macroautophagy/autophagy in lung tissues of mice and A549 cells. Mechanically, S. pneumoniae induced autophagosomal degradation of OCLN leading to AEB impairment in the A549 monolayer. S. pneumoniae released the pEVs that could be internalized by alveolar epithelial cells. Through proteomics, we profiled the cargo proteins inside pEVs and found that these pEVs contained many virulence factors, among which we identified a eukaryotic-like serine-threonine kinase protein StkP. The internalized StkP could induce the phosphorylation of BECN1 (beclin 1) at Ser93 and Ser96 sites, initiating autophagy and resulting in autophagy-dependent OCLN degradation and AEB dysfunction. Finally, the deletion of stkP in S. pneumoniae completely protected infected mice from death, significantly alleviated OCLN degradation in vivo, and largely abolished the AEB disruption caused by pEVs in vitro. Overall, our results suggested that pEVs played a crucial role in the spread of S. pneumoniae virulence factors. The cargo protein StkP in pEVs could communicate with host target proteins and even hijack the BECN1 autophagy initiation pathway, contributing to AEB disruption and bacterial pathogenicity.Abbreviations: AEB: alveolarepithelial barrier; AECs: alveolar epithelial cells; ATG16L1: autophagy related 16 like 1; ATP:adenosine 5'-triphosphate; BafA1: bafilomycin A1; BBB: blood-brain barrier; CFU: colony-forming unit; co-IP: co-immunoprecipitation; CQ:chloroquine; CTRL: control; DiO: 3,3'-dioctadecylox-acarbocyanineperchlorate; DOX: doxycycline; DTT: dithiothreitol; ECIS: electricalcell-substrate impedance sensing; eGFP: enhanced green fluorescentprotein; ermR: erythromycin-resistance expression cassette; Ery: erythromycin; eSTKs: eukaryotic-like serine-threoninekinases; EVs: extracellular vesicles; HA: hemagglutinin; H&E: hematoxylin and eosin; HsLC3B: human LC3B; hpi: hours post-infection; IP: immunoprecipitation; KD: knockdown; KO: knockout; LAMP1: lysosomal associated membrane protein 1; LC/MS: liquid chromatography-mass spectrometry; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MVs: membranevesicles; NC:negative control; NETs:neutrophil extracellular traps; OD: optical density; OMVs: outer membrane vesicles; PBS: phosphate-buffered saline; pEVs: S.pneumoniaeextracellular vesicles; protK: proteinase K; Rapa: rapamycin; RNAi: RNA interference; S.aureus: Staphylococcusaureus; SNF:supernatant fluid; sgRNA: single guide RNA; S.pneumoniae: Streptococcuspneumoniae; S.suis: Streptococcussuis; TEER: trans-epithelium electrical resistance; moi: multiplicity ofinfection; TEM:transmission electron microscope; TJproteins: tight junction proteins; TJP1/ZO-1: tight junction protein1; TSA: tryptic soy agar; WB: western blot; WT: wild-type.

Gingipain-carrying outer membrane vesicles from Porphyromonas gingivalis cause barrier dysfunction of Caco-2 cells by releasing gingipain into the cytosol.

Ingestion of Porphyromonas gingivalis, a periodontal pathogen, disrupts the intestinal barrier in mice. However, the involvement of outer membrane vesicles (OMVs) secreted from P. gingivalis in the destruction of the intestinal barrier remains unclear. In this study, we tested the hypothesis that OMVs carrying gingipains, the major cysteine proteases produced by P. gingivalis, affects the intestinal barrier function. OMVs increased the permeability of the Caco-2 cell monolayer, a human intestinal epithelial cell line, accompanied by degradation of the tight junction protein occludin. In contrast, OMVs prepared from mutant strains devoid of gingipains failed to induce intestinal barrier dysfunction or occludin degradation in Caco-2 cells. A close histological examination revealed the intracellular localization of gingipain-carrying OMVs. Gingipain activity was detected in the cytosolic fraction of Caco-2 cells after incubation with OMVs. These results suggest that gingipains were internalized into intestinal cells through OMVs and transported into the cytosol, where they then directly degraded occludin from the cytosolic side. Thus, P. gingivalis OMVs might destroy the intestinal barrier and induce systemic inflammation via OMV itself or intestinal substances leaked into blood vessels, causing various diseases.

Lipopolysaccharide, VE-cadherin, HMGB1, and HIF-1α levels are elevated in the systemic circulation in chronic migraine patients with medication overuse headache: evidence of leaky gut and inflammation.

OBJECTIVE: Medication overuse headache (MOH) was recently shown to be associated with leaky gut in rodents. We aimed to investigate whether chronic migraine (CM) patients with MOH have elevated lipopolysaccharide levels and inflammatory molecules in blood circulation. MATERIALS AND METHODS: The study included women participants (40 CM patients with NSAID overuse headache, 35 episodic migraine (EM) patients, and 20 healthy non-headache sufferers). Migraine duration, monthly migraine headache days, MigSCog, HADS-D, HADS-A, and HIT-6 scores were recorded. Serum samples were collected to measure circulating LPS, LPS binding protein (LBP), tight junction protein occludin, adherens junction protein vascular endothelial cadherin (VE-cadherin), CGRP, HMGB1, HIF-1α, IL-6, and IL-17 levels. RESULTS: Serum LPS, VE-Cadherin, CGRP, HIF-1α, and IL-6 levels were significantly higher in the CM + MOH group compared to the EM group and healthy controls while serum LBP and HMGB1 were higher in the CM + MOH group compared to healthy controls. IL-17 and occludin levels were comparable between the three groups. Serum HMGB1 levels in EM patients were higher compared to the control group. Mig-SCog and HIT-6 scores were higher in the CM + MOH group compared to EM patients. HADS-A and HADS-D scores were significantly higher in the CM + MOH group compared to EM patients and healthy controls, and they were also higher in EM patients compared to healthy subjects. LPS levels were correlated with VE-cadherin and occludin levels. The number of monthly migraine headache days was positively correlated with serum LPS, HIF-1α, VE-cadherin, and IL-6 levels, HADS-A, HADS-D, HIT-6, and MigSCog scores. CONCLUSION: We have evidence for the first time that CM + MOH is associated with elevated serum LPS and LBP levels suggestive of LPS leak into the systemic circulation. Higher levels of nociceptive and/or pro-inflammatory molecules such as HMGB1, HIF-1α, IL-6, and CGRP may play a role in trigeminal sensitization and neurobiology of MOH. Intestinal hyperpermeability and consequent inflammatory response should be considered as a potential contributory factor in patients with MOH.

The combination model of serum occludin and clinical risk factors improved the efficacy for predicting hemorrhagic transformation in stroke patients with recanalization.

Background: and Purpose: Hemorrhagic transformation (HT) is one of the severe complications in acute ischemic stroke, especially for the patients who undergo recanalization treatment. It is crucial to screen patients who have high risk of HT before recanalization. However, current prediction models based on clinical factors are not ideal for clinical practice. Serum occludin, a biomarker for cerebral ischemia-induced blood-brain barrier disruption, has potential for predicting HT. This study was to investigate whether the combination of serum occludin and clinical risk factors improved the efficacy of predicting HT. Methods: This was a single-center prospective observational study. Baseline clinical data and blood samples of recanalization patients were collected upon admission to our hospital. The level of serum occludin was measured using enzyme-linked immunosorbent assay. The diagnosis of HT was confirmed by CT scans within 36 h post recanalization. Results: A total of 324 patients with recanalization were enrolled and 68 patients presented HT occurrence. HT patients had the higher level of baseline occludin than patients without HT (p < 0.001). Multivariate regression analysis showed that serum occludin level, Alberta Stroke Program Early CT Scores and endovascular therapy were independent risk factors (p < 0.05) for HT after adjusting potential confounders. The combination of serum occludin and clinical risk factors significantly improved the accuracy of predicting HT [area under the curve (AUC, 0.821 vs 0.701, p < 0.001), and net reclassification improvement (31.1 %), integrated discrimination improvement (21.5 %), p < 0.001] compared to a model employing only clinical risk factors. The modified AUC (0.806) of combined model based on 10-fold-cross-validation was still higher than clinical risk model (0.701). Conclusion: The combination of serum occludin and clinical risk factors significantly improved the prediction efficacy for HT, providing a novel potential prediction model to screen for patients with high risk of HT before recanalization in acute ischemic stroke.

Campylobacter jejuni Surface-Bound Protease HtrA, but Not the Secreted Protease nor Protease in Shed Membrane Vesicles, Disrupts Epithelial Cell-to-Cell Junctions.

Fundamental functions of the intestinal epithelium include the digestion of food, absorption of nutrients, and its ability to act as the first barrier against intruding microbes. Campylobacter jejuni is a major zoonotic pathogen accounting for a substantial portion of bacterial foodborne illnesses. The germ colonizes the intestines of birds and is mainly transmitted to humans through the consumption of contaminated poultry meat. In the human gastrointestinal tract, the bacterium triggers campylobacteriosis that can progress to serious secondary disorders, including reactive arthritis, inflammatory bowel disease and Guillain-Barré syndrome. We recently discovered that C. jejuni serine protease HtrA disrupts intestinal epithelial barrier functions via cleavage of the tight and adherens junction components occludin, claudin-8 and E-cadherin. However, it is unknown whether epithelial damage is mediated by the secreted soluble enzyme, by HtrA contained in shed outer-membrane vesicles (OMVs) or by another mechanism that has yet to be identified. In the present study, we investigated whether soluble recombinant HtrA and/or purified OMVs induce junctional damage to polarized intestinal epithelial cells compared to live C. jejuni bacteria. By using electron and confocal immunofluorescence microscopy, we show that HtrA-expressing C. jejuni bacteria trigger efficient junctional cell damage, but not soluble purified HtrA or HtrA-containing OMVs, not even at high concentrations far exceeding physiological levels. Instead, we found that only bacteria with active protein biosynthesis effectively cleave junctional proteins, which is followed by paracellular transmigration of C. jejuni through the epithelial cell layer. These findings shed new light on the pathogenic activities of HtrA and virulence strategies of C. jejuni.

Canonical and Non-Canonical Localization of Tight Junction Proteins during Early Murine Cranial Development.

This study investigates the intricate composition and spatial distribution of tight junction complex proteins during early mouse neurulation. The analyses focused on the cranial neural tube, which gives rise to all head structures. Neurulation brings about significant changes in the neuronal and non-neuronal ectoderm at a cellular and tissue level. During this process, precise coordination of both epithelial integrity and epithelial dynamics is essential for accurate tissue morphogenesis. Tight junctions are pivotal for epithelial integrity, yet their complex composition in this context remains poorly understood. Our examination of various tight junction proteins in the forebrain region of mouse embryos revealed distinct patterns in the neuronal and non-neuronal ectoderm, as well as mesoderm-derived mesenchymal cells. While claudin-4 exhibited exclusive expression in the non-neuronal ectoderm, we demonstrated a neuronal ectoderm specific localization for claudin-12 in the developing cranial neural tube. Claudin-5 was uniquely present in mesenchymal cells. Regarding the subcellular localization, canonical tight junction localization in the apical junctions was predominant for most tight junction complex proteins. ZO-1 (zona occludens protein-1), claudin-1, claudin-4, claudin-12, and occludin were detected at the apical junction. However, claudin-1 and occludin also appeared in basolateral domains. Intriguingly, claudin-3 displayed a non-canonical localization, overlapping with a nuclear lamina marker. These findings highlight the diverse tissue and subcellular distribution of tight junction proteins and emphasize the need for their precise regulation during the dynamic processes of forebrain development. The study can thereby contribute to a better understanding of the role of tight junction complex proteins in forebrain development.

Altered Expression of Intestinal Tight Junctions in Patients with Chronic Kidney Disease: A Pathogenetic Mechanism of Intestinal Hyperpermeability.

BACKGROUND: Systemic inflammation in chronic kidney disease (CKD) is associated (as a cause or effect) with intestinal barrier dysfunction and increased gut permeability, with mechanisms not yet fully understood. This study investigated different parameters of the intestinal barrier in CKD patients, especially tight junction (TJ) proteins and their possible association with systemic endotoxemia and inflammation. METHODS: Thirty-three patients with stage I-IV CKD (n = 17) or end-stage kidney disease (ESKD) (n = 16) and 11 healthy controls underwent duodenal biopsy. Samples were examined histologically, the presence of CD3+ T-lymphocytes and the expression of occludin and claudin-1 in the intestinal epithelium was evaluated by means of immunohistochemistry, circulating endotoxin concentrations were determined by means of ELISA and the concentrations of the cytokines IL-1ß, IL-6, IL-8, IL-10 and TNF-α in serum were measured using flow cytometry. RESULTS: Patients with stage I-IV CKD or ESKD had significantly higher serum endotoxin, IL-6, IL-8 and IL-10 levels compared to controls. Intestinal occludin and claudin-1 were significantly decreased, and their expression was inversely correlated with systemic endotoxemia. Regarding occludin, a specific expression pattern was observed, with a gradually increasing loss of its expression from the crypt to the tip of the villi. CONCLUSION: The expression of occludin and claudin-1 in enterocytes is significantly reduced in patients with CKD, contributing to systemic endotoxemia and inflammatory responses in these patients.