Endogenous FGF21 attenuates blood-brain barrier disruption in penumbra after delayed recanalization in MCAO rats through FGFR1/PI3K/Akt pathway / 中南大学学报(医学版)

OBJECTIVES@#Restoration of blood circulation within "time window" is the principal treating goal for treating acute ischemic stroke. Previous studies revealed that delayed recanalization might cause serious ischemia/reperfusion injury. However, plenty of evidences showed delayed recanalization improved neurological outcomes in acute ischemic stroke. This study aims to explore the role of delayed recanalization on blood-brain barrier (BBB) in the penumbra (surrounding ischemic core) and neurological outcomes after middle cerebral artery occlusion (MCAO).@*METHODS@#Recanalization was performed on the 3rd day after MCAO. BBB disruption was tested by Western blotting, Evans blue dye, and immunofluorescence staining. Infarct volume and neurological outcomes were evaluated on the 7th day after MCAO. The expression of fibroblast growth factor 21 (FGF21), fibroblast growth factor receptor 1 (FGFR1), phosphatidylinositol-3-kinase (PI3K), and serine/threonine kinase (Akt) in the penumbra were observed by immunofluorescence staining and/or Western blotting.@*RESULTS@#The extraversion of Evans blue, IgG, and albumin increased surrounding ischemic core after MCAO, but significantly decreased after recanalization. The expression of Claudin-5, Occludin, and zona occludens 1 (ZO-1) decreased surrounding ischemic core after MCAO, but significantly increased after recanalization. Infarct volume reduced and neurological outcomes improved following recanalization (on the 7th day after MCAO). The expressions of Claudin-5, Occludin, and ZO-1 decreased surrounding ischemic core following MCAO, which were up-regulated corresponding to the increases of FGF21, p-FGFR1, PI3K, and p-Akt after recanalization. Intra-cerebroventricular injection of FGFR1 inhibitor SU5402 down-regulated the expression of PI3K, p-Akt, Occludin, Claudin-5, and ZO-1 in the penumbra, which weakened the beneficial effects of recanalization on neurological outcomes after MCAO.@*CONCLUSIONS@#Delayed recanalization on the 3rd day after MCAO increases endogenous FGF21 in the penumbra and activates FGFR1/PI3K/Akt pathway, which attenuates BBB disruption in the penumbra and improves neurobehavior in MCAO rats.

Xuebijing Injection Ameliorates H / 中国结合医学杂志

OBJECTIVE@#To investigate the protective effects and underlying mechanisms of Xuebijing Injection (XBJ) on the lung endothelial barrier in hydrogen sulfide (H@*METHODS@#Sprague-Dawley rats were exposed to H@*RESULTS@#The morphological investigation showed that XBJ attenuated H@*CONCLUSIONS@#XBJ ameliorated H

Arg-Leu-Tyr-Glu Suppresses Retinal Endothelial Permeability and Choroidal Neovascularization by Inhibiting the VEGF Receptor 2 Signaling Pathway

Vascular endothelial growth factor (VEGF) plays a pivotal role in pathologic ocular neovascularization and vascular leakage via activation of VEGF receptor 2 (VEGFR2). This study was undertaken to evaluate the therapeutic mechanisms and effects of the tetrapeptide Arg-Leu-Tyr-Glu (RLYE), a VEGFR2 inhibitor, in the development of vascular permeability and choroidal neovascularization (CNV). In cultured human retinal microvascular endothelial cells (HRMECs), treatment with RLYE blocked VEGF-A-induced phosphorylation of VEGFR2, Akt, ERK, and endothelial nitric oxide synthase (eNOS), leading to suppression of VEGF-A-mediated hyper-production of NO. Treatment with RLYE also inhibited VEGF-A-stimulated angiogenic processes (migration, proliferation, and tube formation) and the hyperpermeability of HRMECs, in addition to attenuating VEGF-A-induced angiogenesis and vascular permeability in mice. The anti-vascular permeability activity of RLYE was correlated with enhanced stability and positioning of the junction proteins VE-cadherin, β-catenin, claudin-5, and ZO-1, critical components of the cortical actin ring structure and retinal endothelial barrier, at the boundary between HRMECs stimulated with VEGF-A. Furthermore, intravitreally injected RLYE bound to retinal microvascular endothelium and inhibited laser-induced CNV in mice. These findings suggest that RLYE has potential as a therapeutic drug for the treatment of CNV by preventing VEGFR2-mediated vascular leakage and angiogenesis.

Impact of the Endothelial Tight Junction Protein Claudin-5 on Clinical Profiles of Patients With COPD

PURPOSE: The tight junction protein claudin-5 (CLDN5) is critical to the control of endothelial cellular polarity and pericellular permeability. The role of CLDN5 in chronic obstructive pulmonary disease (COPD) remains unclear. The aim of this study was to investigate the association between CLDN5 levels and clinical variables in patients with COPD. METHODS: In total, 30 patients with COPD and 30 healthy controls were enrolled in the study. The plasma CLDN5 level was checked in patients with stable or exacerbated COPD and in healthy controls. RESULTS: The mean plasma CLDN5 level of patients with COPD was 0.63 ± 0.05 ng/mL and that of healthy controls was 6.9 ± 0.78 ng/mL (P = 0.001). The mean plasma CLDN5 level was 0.71 ± 0.05 ng/mL in exacerbated COPD patients and 0.63 ± 0.04 ng/mL in patients with stable COPD (P < 0.05). The plasma CLDN5 level among COPD subjects was correlated with the smoking amount (r = −0.530, P = 0.001). The plasma CLDN5 level in stable COPD patients was correlated with forced expiratory volume in one second (FEV1, %pred.) (r = −0.481, P = 0.037). CONCLUSIONS: The plasma CLDN5 level was not correlated with age. CLDN5 may be involved in the pathogenesis of COPD. Further studies having a larger sample size will be needed to clarify CLDN5 in COPD.

Cortical Inflammation is Increased in a DSS-Induced Colitis Mouse Model / 神经科学通报·英文版

While inflammatory bowel disease (IBD) might be a risk factor in the development of brain dysfunctions, the underlying mechanisms are largely unknown. Here, mice were treated with 5% dextran sodium sulfate (DSS) in drinking water and sacrificed on day 7. The serum level of IL-6 increased, accompanied by elevation of the IL-6 and TNF-α levels in cortical tissue. However, the endotoxin concentration in plasma and brain of mice with DSS-induced colitis showed a rising trend, but with no significant difference. We also found significant activation of microglial cells and reduction in occludin and claudin-5 expression in the brain tissue after DSS-induced colitis. These results suggested that DSS-induced colitis increases systemic inflammation which then results in cortical inflammation via up-regulation of serum cytokines. Here, we provide new information on the impact of colitis on the outcomes of cortical inflammation.

Protective effect of catalpolon destruction of tight junctions of high glucose induced BMECs / 中国中药杂志

This paper aimed to observe the protective effect of catalpol on the high glucose induced destruction of tight junctions of rat primary brain microvascular endothelial cells (BMECs). Catalpol co-administrated with high glucose increased BMECs survival, decreased its ET-1 secretion, and improved transmembrane electrical resistance in a time-dependent manner. Furthermore, transmission electron microscopy was used to observe catalpol's protective effect on tight junction. Fluorescence staining displayed that catalpol reversed the rearrangement of the cytoskeleton protein F-actin and up-regulated the tight junction proteins claudin-5 and ZO-1, which were further demonstrated by the mRNA expression levels of claudin-5, occludin, ZO-1, ZO-2, ZO-3, -actintin, vinculin and cateinins. This study indicated that catalpol reverses the disaggregation of cytoskeleton actin in BMECs and up-regulates the expression of tight junction proteins, such as claudin-5, occludin, and ZO-1, and finally alleviates the increase in high glucose-induced BMECs injury.

Contribution of Borneolum syntheticum to the Intervention Effect of Liuwei Dihuang Pill () on Experimental Retinal Degeneration / 中国结合医学杂志

<p><b>OBJECTIVE</b>To observe the contribution of Borneolum syntheticum to the intervention effect of Liuwei Dihuang Pill (, LDP) on experimental retinal degeneration, and initially investigate the mechanism of Borneolum syntheticum as meridian-lead-in drug.</p><p><b>METHODS</b>A total of 180 sodium iodateinduced retinital degeneration rats were randomly divided into three groups, including distilled water group, LDP group, and LDP+Borneolum syntheticum (LDP+BS) group. Twenty normal rats were fed regularly without any treatment as normal control. On day 7 and 14 after treatment, histopathological study and transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) test were performed to evaluate the retinopathy. Claudin-5 expression at blood-retina barrier (BRB) was detected by Western blot at different time points from 0.5 to 8 h after gavage.</p><p><b>RESULTS</b>On day 7 and 14 after treatment, the retinal lesion grades were significantly different among the three groups (P<0.05). The grade in the LDP+BS group was significantly less than the LDP and distilled water groups (both P<0.05), no significant difference was observed between the LDP and distilled water groups (P>0.05). The apoptosis rates in the LDP+BS group was significantly less than the distilled water and LDP groups (both P<0.05), while there was no significant difference between LDP and distilled water groups (P>0.05). Expression of claudin-5 in LDP+BS group was significantly less than the other two groups at 0.5, 1 and 2 h after gavage (P<0.05). There was no apparent difference among the three groups at 4 and 8 h after gavage (P>0.05).</p><p><b>CONCLUSION</b>Borneolum syntheticum could strengthen the effect of LDP on experimental retinal degeneration, indicated that Borneolum syntheticum might play the role of meridian-lead-in drug in the formula. The mechanism may be due to Borneolum syntheticum could promote the physiologically openness of bloodretina barrier through transiently affecting the expression of claudin-5.</p>

Effects of High Glucose and Dexamethasone on the Permeability in Trabecular Meshwork Cells

PURPOSE: To investigate the effects of high glucose (HG) and dexamethasone (DEX) on the survival and permeability of trabecular meshwork cells (HTMC), and associated changes in tight junctions. METHODS: Primary cultured HTMC were exposed to 5 mM low glucose (LG) or 25 mM HG with or without 1.0 µM DEX for 3 days. The permeability of the HTMC monolayer was assessed using carboxyfluorescein or transendothelial electrical resistance (TEER). Gene and protein expressions of claudin-5 and occludin were assessed with reverse transcription polymerase chain reaction (RT-PCR) and Western blot, respectively. RESULTS: HG was significantly associated with greater HTMC monolayer permeability compared to LG by both the carboxyfluorescein permeability test and TEER (p = 0.022, 0.028). HG also decreased claudin-5 and occludin mRNA expression, respectively (7.5%, 12.9%). DEX abolished HG-induced increased permeability, and increased the protein expression of claudin-5 and occludin, respectively (p = 0.015, 0.012). CONCLUSIONS: In HTMCs, DEX reversed HG-induced permeability increase. DEX increased tight junction molecules claudin-5 and occludin. Thus, DEX-induced changes in junctional proteins could be another mechanism of increased resistance through the trabecular meshwork and may result in steroid-induced glaucoma.

Rhubarb Monomers Protect Intestinal Mucosal Barrier in Sepsis via Junction Proteins / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Leakage of the intestinal mucosal barrier may cause translocation of bacteria, then leading to multiorgan failure. This study hypothesized that rhubarb monomers might protect the gut mucosal barrier in sepsis through junction proteins.</p><p><b>METHODS</b>Healthy male Sprague-Dawley rats (weighing 230-250 g) under anesthesia and sedation were subjected to cecal ligation and perforation (CLP). After surgical preparation, rats were randomly assigned to eight groups (n = 6 or 8 each group): sham group (Group A: normal saline gavage); sepsis group (Group B: normal saline gavage); Group C (intraperitoneally, dexamethasone 0.5 mg/kg) immediately after CLP surgery; and rhubarb monomer (100 mg/kg in normal saline)-treated groups (Group D: rhein; Group E: emodin; Group F: 3,8-dihydroxy-1-methyl-anthraquinone-2-carboxylic acid; Group G: 1-O-caffeoyl-2-(4-hydroxy-O-cinnamoyl)-D-glucose; and Group H: daucosterol linoleate). Animals were sacrificed after 24 h. Intestinal histology, lactulose, mannitol concentrations were measured, and zonula occludens (ZO)-1, occludin and claudin-5 transcription (polymerase chain reaction), translation (by Western blot analysis), and expression (by immunohistochemistry) were also measured.</p><p><b>RESULTS</b>Intestinal histology revealed injury to intestinal mucosal villi induced by sepsis in Group B, compared with Group A. Compared with Group A (0.17 ± 0.41), the pathological scores in Groups B (2.83 ± 0.41, P < 0.001), C (1.83 ± 0.41, P < 0.001), D (2.00 ± 0.63, P < 0.001), E (1.83 ± 0.41, P < 0.001), F (1.83 ± 0.75, P < 0.001), G (2.17 ± 0.41, P < 0.001),and H (1.83 ± 0.41, P < 0.001) were significantly increased. Lactulose/mannitol (L/M) ratio in Group B (0.046 ± 0.003) was significantly higher than in Group A (0.013 ± 0.001, P< 0.001) while L/M ratios in Groups C (0.028 ± 0.002, P< 0.001), D (0.029 ± 0.003, P< 0.001), E (0.026 ± 0.003, P< 0.001), F (0.027 ± 0.003, P< 0.001), G (0.030 ± 0.005, P< 0.001), and H (0.026 ± 0.002, P< 0.001) were significantly lower than that in Group B. ZO-1, occludin and claudin-5 transcription, translation, and expression in Group B were significantly lower than that in Group A (P < 0.001), but they were significantly higher in Groups C, D, E, F, G, and H than those in Group B (P < 0.05).</p><p><b>CONCLUSION</b>Rhubarb monomer treatment ameliorated mucosal damage in sepsis via enhanced transcription, translation, and expression of junction proteins.</p>

Resveratrol attenuates lipopolysaccharide-induced dysfunction of blood-brain barrier in endothelial cells via AMPK activation

Resveratrol, a phytoalexin, is reported to activate AMP-activated protein kinase (AMPK) in vascular cells. The blood-brain barrier (BBB), formed by specialized brain endothelial cells that are interconnected by tight junctions, strictly regulates paracellular permeability to maintain an optimal extracellular environment for brain homeostasis. The aim of this study was to elucidate the effects of resveratrol and the role of AMPK in BBB dysfunction induced by lipopolysaccharide (LPS). Exposure of human brain microvascular endothelial cells (HBMECs) to LPS (1 µg/ml) for 4 to 24 hours week dramatically increased the permeability of the BBB in parallel with lowered expression levels of occluding and claudin-5, which are essential to maintain tight junctions in HBMECs. In addition, LPS significantly increased the reactive oxygen species (ROS) productions. All effects induced by LPS in HBVMCs were reversed by adenoviral overexpression of superoxide dismutase, inhibition of NAD(P) H oxidase by apocynin or gain-function of AMPK by adenoviral overexpression of constitutively active mutant (AMPK-CA) or by resveratrol. Finally, upregulation of AMPK by either AMPK-CA or resveratrol abolished the levels of LPS-enhanced NAD(P)H oxidase subunits protein expressions. We conclude that AMPK activation by resveratrol improves the integrity of the BBB disrupted by LPS through suppressing the induction of NAD(P)H oxidase-derived ROS in HBMECs.

Claudin-1, -2, -4, and -5: comparison of expression levels and distribution in equine tissues

Claudins, which are known as transmembrane proteins play an essential role in tight junctions (TJs) to form physical barriers and regulate paracellular transportation. To understand equine diseases, it is helpful to measure the tissue-specific expression of TJs in horses. Major equine diseases such as colic and West Nile cause damage to TJs. In this study, the expression level and distribution of claudin-1, -2, -4, and -5 in eight tissues were assessed by Western blotting and immunohistochemistry methods. Claudin-1 was primarily identified in the lung, duodenum, and uterus, claudin-2 was evenly observed in equine tissues, claudin-4 was abundantly detected in the liver, kidney and uterus, and claudin-5 was strongly expressed in the lung, duodenum, ovary, and uterus, as determined by Western blotting method. The localization of equine claudins was observed by immunohistochemistry methods. These findings provide knowledge regarding the expression patterns and localization of equine claudins, as well as valuable information to understand tight junction-related diseases according to tissue specificity and function of claudins in horses.

Dehydroascorbic Acid Attenuates Ischemic Brain Edema and Neurotoxicity in Cerebral Ischemia: An in vivo Study

Ischemic stroke results in the diverse phathophysiologies including blood brain barrier (BBB) disruption, brain edema, neuronal cell death, and synaptic loss in brain. Vitamin C has known as the potent anti-oxidant having multiple functions in various organs, as well as in brain. Dehydroascorbic acid (DHA) as the oxidized form of ascorbic acid (AA) acts as a cellular protector against oxidative stress and easily enters into the brain compared to AA. To determine the role of DHA on edema formation, neuronal cell death, and synaptic dysfunction following cerebral ischemia, we investigated the infarct size of ischemic brain tissue and measured the expression of aquaporin 1 (AQP-1) as the water channel protein. We also examined the expression of claudin 5 for confirming the BBB breakdown, and the expression of bcl 2 associated X protein (Bax), caspase-3, inducible nitric oxide synthase (iNOS) for checking the effect of DHA on the neurotoxicity. Finally, we examined postsynaptic density protein-95 (PSD-95) expression to confirm the effect of DHA on synaptic dysfunction following ischemic stroke. Based on our findings, we propose that DHA might alleviate the pathogenesis of ischemic brain injury by attenuating edema, neuronal loss, and by improving synaptic connection.

Effect of fluid shear stress on the cellular morphology and tight junction of laryngeal squamous carcinoma Hep2 cells / 生物医学工程学杂志

This paper is aimed to investigate the effect of fluid shear stress on the tight junction of laryngeal squamous carcinoma (Hep2) cells and to explore the potential molecular mechanism. Hep2 cells were selected and subjected to the fluid shear stress of 1.4 dyn/cm2 for different time, respectively. The morphological changes of Hep2 cells under shear stress were observed using inverted microscope. The cell-cell junctions were examined by transmission electron microscope (TEM). The expressions of tight junction proteins (including Occludin, Claudin-5 and ZO-1) and the distribution of Claudin-5 were examined by Western blot assay and laser scanning confocal microscope, respectively. The results indicated that Hep2 cells turned to spindle-like shapes after exposed to shear stress, and showed the trend of the recovering to original shapes when the shear stress was cancelled. The cell-cell junctions were tight under the shear flow condition, and the permeability was reduced under the condition of 1.4 dyn/cm shear flow. The expressions of tight junction proteins were enhanced with increased duration of shear flow, but reduced after removing shear flow. The result of Claudin-5 expression by immufluorescence assay was consistent with that by Western blot. The Claudin-5 mainly distributed in the cytoplasm under static condition, while it located at the intercellular after shear flow stimulation, and it appeared intercellular and cytoplasm after stopping shear flow stimulation. Therefore, it can be concluded that shear stress changes the morphology of laryngeal squamous carcinoma Hep2 cells, and upregulates the tight junction.

Evaluation of the expression and significance of Claudin-5 and CD99 in solid-pseudopapillary neoplasms and neuroendocrine tumors of pancreas / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate the expression of endothelium tight junction protein Claudin-5 and intercellular adhesion molecule CD99 in solid-pseudopapillary neoplasms (SPN) and neuroendocrine tumors of pancreas (P-NET), and their significance in the differential diagnoses.</p><p><b>METHODS</b>Immunohistochemical staining of Claudin-5 and CD99 was performed in 37 cases SPN and 21 cases of P-NET.</p><p><b>RESULTS</b>Membranous Claudin-5 expression was observed in all cases of SPN but was absent in all cases of P-NET. The difference was significant (P < 0.01). In SPN, 91.9% (34/37) of the cases displayed paranuclear dot-like immunoreactivity for CD99; in contrast, 61.9% (13/21) of the cases of P-NET displayed membranous staining (P < 0.01). There was a positive association between the expression of Claudin-5 and CD99 in SPN (r = 0.421,P = 0.001).</p><p><b>CONCLUSIONS</b>Although the macroscopic and microscopic features of SPN are quite characteristic, they may not allow confident differentiation from P-NET in all cases, especially when these characteristics are not classical. If necessary, immunostaining for Claudin-5 and CD99 can help to differentiate between these entities.</p>

Chlorogenic Acid Decreases Retinal Vascular Hyperpermeability in Diabetic Rat Model

To evaluate the effect of chlorogenic acid (CGA), a polyphenol abundant in coffee, on retinal vascular leakage in the rat model of diabetic retinopathy, Sprague-Dawley rats were divided into four groups: controls, streptozotocin-induced diabetic rats, and diabetic rats treated with 10 and 20 mg/kg chlorogenic acid intraperitoneally daily for 14 days, respectively. Blood-retinal barrier (BRB) breakdown was evaluated using FITC-dextran. Vascular endothelial growth factor (VEGF) distribution and expression level was evaluated with immunohistochemistry and Western blot analysis. Expression of tight junction proteins, occludin and claudin-5, and zonula occludens protein, ZO-1 was also evaluated with immunohistochemistry and Western blot analysis. BRB breakdown and increased vascular leakage was found in diabetic rats, with increased VEGF expression and down-regulation of occludin, claudin-5, and ZO-1. CGA treatment effectively preserved the expression of occludin, and decreased VEGF levels, leading to less BRB breakdown and less vascular leakage. CGA may have a preventive role in BRB breakdown in diabetic retinopathy by preserving tight junction protein levels and low VEGF levels.

Correlation between Claudins Expression and Prognostic Factors in Prostate Cancer

PURPOSE: The purpose of this study was to evaluate the correlation between the expression of claudins and prognostic factors in patients with prostate cancer. MATERIALS AND METHODS: The subjects of this study were 48 patients who had undergone surgery for prostate cancer. The Gleason score (6 or lower, 7 or higher), prostate-specific antigen (PSA) level, T stage, biochemical recurrence, local recurrence, and distant metastasis were compared according to the expression of claudin-1 and claudin-5 in prostate cancer. RESULTS: In the group with a low expression of claudin-1, the Gleason score was 7 points or higher in 18 cases (82%) and 6 points or lower in 4 cases (18%). In the group with a high expression of claudin-1, the Gleason score was 7 points or higher in 13 cases (50%) and 6 points or lower in 13 cases (50%). Thus, the low-expression group had more cases with a Gleason score of 7 or higher (p=0.022). The group with a low expression of claudin-5 also had more cases with a Gleason score of 7 or higher (p=0.011). The mean PSA values in the groups with a low and high expression of claudin-1 were 9.6 ng/ml and 5.6 ng/ml, respectively (p=0.007). A low expression of claudin-5 was also associated with a high PSA value (p=0.002). There was no statistical difference in the expression of claudin-1 and claudin-5 by T stage, biochemical recurrence, local recurrence, or distant metastasis. CONCLUSIONS: The low expression of claudin-1, claudin-5 was associated with a Gleason score of 7 or higher and a high PSA value in prostate cancer.

Indol-3-Carbinol Regulated Tight Junction Permeability and Associated-Protein Level and Suppressed Cell Invasion in Human Colon Cancer Cell Line, HT-29

To determine whether indol-3-carbinol (I3C, C9H9NO), an autolysis product of a glucosinolate and a glucobrassicin in vegetables, regulated tight junction proteins (TJ) and suppressed cell invasion in colon cancer cells,this experiment was performed. Our results indicate that I3C inhibit cell growth of HT-29 cells in a dose (0, 50, 100 micrometer) and time (0, 24 and 48 h) dependent manner. Using the wound healing and matrigel invasion study, respectively, I3C inhibits the cell motility and invasion of the ovarian cancer cell line. The TEER values were increased in HT-29 cells grown in transwells treated with I3C, reversely, paracellular permeability was decreased in those of condition. Claudin-1, claudin-5, ZO-1 and occuldin have been shown to be positively expressed in HT-29 coloncancer cells. I3C occurs concurrently with a significant decrease in the levels of those of proteins in HT-29 cells. But E-cadherin level in the HT-29 was increased by I3C. The reduction of claudin-1 and claudin-5 protein levels occurred post-transcriptionaly since their mRNA levels are no difference by I3C. Therefore, our results suggest that I3C may be expected to inhibit cancer metastasis and invasion by tighten the cell junction and restoring tight junction in colon cancer cell line, HT-29.