Endothelial tight junctions (TJs) serve as an important barrier in vascular endothelial structure and maintain vascular function homeostasis. Occludin, the most representative tight junction protein, is involved in sealing cell connections and maintaining the integrity and permeability of vascular endothelium. Recent studies have shown that alterations in the expression, distribution, and structure of endothelial TJs may lead to many related vascular diseases and pathologies (such as stroke, atherosclerosis, and pulmonary hypertension etc.). Here, we reviewed the research advances on the relationship between occludin and vascular endothelial injury, including the biological information of occludin, the signal pathways that occludin exerts the protective effect of vascular endothelium, and the relationship between occludin and vascular endothelial injury-related diseases.
Endothelium, Vascular ; Occludin/genetics* ; Signal Transduction ; Tight Junctions

OBJECTIVE: To explore the possible effects and mechanism of Zhizhu Decoction (ZZD) on the pathophysiology of slow transit constipation (STC). METHODS: A total of 54 C57BL/6 mice was randomly divided into the following 6 groups by a random number table, including control, STC model (model), positive control, and low-, medium- and high-doses ZZD treatment groups (5, 10, 20 g/kg, namely L, M-, and H-ZZD, respectively), 9 mice in each group. Following 2-week treatment, intestinal transport rate (ITR) and fecal water content were determined, and blood and colon tissue samples were collected. Hematoxylin-eosin and periodic acid-Schiff staining were performed to evaluate the morphology of colon tissues and calculate the number of goblet cells. To determine intestinal permeability, serum levels of lipopolysaccharide (LPS), low-density lipoprotein (LDL) and mannose were measured using enzyme-linked immunosorbent assay (ELISA). Western blot analysis was carried out to detect the expression levels of intestinal tight junction proteins zona-occludens-1 (ZO-1), claudin-1, occludin and recombinant mucin 2 (MUC2). The mRNA expression levels of inflammatory cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-4, IL-10 and IL-22 were determined using reverse transcription-quantitative reverse transcription reaction. Colon indexes of oxidative stress were measured by ELISA, and protein expression levels of colon silent information regulator 1/forkhead box O transcription factor 1 (SIRT1/FoxO1) antioxidant signaling pathway were detected by Western blot. RESULTS: Compared with the model group, ITR and fecal moisture were significantly enhanced in STC mice in the M-ZZD and H-ZZD groups (P<0.01). Additionally, ZZD treatment notably increased the thickness of mucosal and muscular tissue, elevated the number of goblet cells in the colon of STC mice, reduced the secretion levels of LPS, LDL and mannose, and upregulated ZO-1, claudin-1, occludin and MUC2 expressions in the colon in a dose-dependent manner, compared with the model group (P<0.05 or P<0.01). In addition, ZZD significantly attenuated intestinal inflammation and oxidative stress and activated the SIRT1/FoxO1 signaling pathway (P<0.05 or P<0.01). CONCLUSION ZZD exhibited beneficial effects on the intestinal system of STC mice and alleviated intestinal inflammation and oxidative stress via activating SIRT1/FoxO1 antioxidant signaling pathway in the colon.
Mice ; Animals ; Sirtuin 1/genetics* ; Antioxidants ; Occludin ; Lipopolysaccharides ; Claudin-1 ; Mannose ; Mice, Inbred C57BL ; Constipation/drug therapy* ; Inflammation ; Signal Transduction

OBJECTIVETo explore the mechanism of electroacupuncture at Zusanli (ST 36) on regulation of intestinal inflammatory reaction in rats with acute pancreatitis.

METHODSFifty-four SD rats were randomly divided into a severe acute pancreatitis (SAP) group, an electroacupuncture (EA) group and a sham-operation (SO) group, 18 cases in each group. 3.5% sodium cholate was used to made SAP model by retrograde injecting in cholangiopancreatic duct. After the success of model making, the EA group was treated with EA at bilateral Zusanli (ST 36) for 30 min. The SO group and the SAP group were fixed at the same time for 30 min without treatment. All the rats were killed at 3 h, 6 h and 12 h after modeling in batches. The pathological changes of pancreatic tissue and intestinal epithelium were observed, and the expression of small intestinal occludin protein and nuclear factor kappa-B (NF-kappaB) were detected by immunohistochemical SP method.

RESULTSThe pathologic score and the expression of small intestinal NF-kappaB p65 at 3 h, 6 h and 12 h after modeling in the EA group and the SO group were significantly lower than those in the SAP group (all P < 0.05), and the expression of small intestinal occludin protein in the EA group and the SO group were significantly higher than that in the SAP group (all P < 0.05).

CONCLUSIONElectroacupuncture at Zusanli (ST 36) can alleviate pancreatic injury by reducing the expression of NF-kappaB p65 and enhancing the expression of occludin protein in the intestinal epithelium in the SAP model rats.

Acupuncture Points ; Acute Disease ; therapy ; Animals ; Electroacupuncture ; Humans ; Intestine, Small ; metabolism ; Male ; NF-kappa B ; genetics ; metabolism ; Occludin ; genetics ; metabolism ; Pancreatitis ; genetics ; metabolism ; therapy ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo analyze the distribution and significance of occludin mRNA expression in human gastric cancer, as well as its relationship with gastric cancer pathology and multidrug resistance (MDR) in vivo.

METHODSIn situ hybridization (ISH) technique was used to evaluate the expression of occludin mRNA in 42 gastric carcinoma specimens obtained by surgery and 23 relatively normal gastric mucosa obtained by gastric endoscopy. All specimens had been stored in cryostatic section.

RESULTSOccludin mRNA was found positive in the cytoplasm of gastric glandulous epithelia as blue particles with intensive stain in 14 of 42 gastric carcinomas (33.3%), 23 of 42 paracancerous gastric tissues (54.8%), 14 of 23 relatively normal gastric tissues (60.9%), 9 of 16 well differentiated carcinomas (56.3%), 4 of 14 moderately differentiated carcinomas (28.6%), 1 of 10 poorly differentiated carcinomas (10.0%) and none of 2 mucosal carcinomas. There were significant differences in occludin mRNA positive rate between relatively normal gastric tissue and gastric cancer as well as between paracancerous gastric tissue and gastric cancer. The expression of occludin mRNA in moderately and poorly differentiated groups was gradually reduced when compared with well differentiated group, which suggests that there be a significant correlation between tumor differentiation and the expression of occludin mRNA. Furthermore, the positive signals of occludin mRNA distributed extensively in the cytoplasm of SGC7901/VCR cell, being vincristine resistant, derived from parental gastric cell line SGC7901. The positive signals of SGC7901/VCR were stronger than those of SGC7901 cells.

CONCLUSIONOccludin mRNA, being mainly located in epithelial cells and its expression correlated with tumor differentiation, may be involved in the development of multi-drug resistance in gastric cancer.

Drug Resistance, Multiple ; physiology ; Drug Resistance, Neoplasm ; physiology ; Humans ; In Situ Hybridization ; Membrane Proteins ; genetics ; metabolism ; Occludin ; RNA, Messenger ; metabolism ; Stomach Neoplasms ; metabolism ; Tight Junctions ; metabolism

OBJECTIVETo evaluate the possible role of tight junction protein Occludin in nasal polyps.

METHODSThe expression of Claudin-1, Occludin and ZO-1 in nasal polyps (n = 20) and healthy uncinate mucosa (n = 15) were examined using immunohistochemical staining, real-time quantitative polymerase chain reaction (PCR) and Western blot analysis. The regulatory effects of proinflammatory cytokines (IFN-γ, IL-13, IL-17, TGF-β, TGF-α) on the expression of Occludin in cultured human nasal epithelial cells were investigated.

RESULTSThe immunohistochemical results showed that Claudin-1, Occludin and ZO-1 were detected both in the nasal polyp group and the control group. The expression sites were the cell membrane and cytoplasm of nasal mucosa epithelial cells. The mean optical density of Claudin-1, Occludin and ZO-1 were 0.187 ± 0.076,0.172 ± 0.109 and 0.098 ± 0.035 respectively in the nasal polyp group and were significantly lower than those in the control group (0.312 ± 0.101, 0.220 ± 0.069 and 0.233 ± 0.093 respectively), the differences were significant (t = 9.345, t = 3.301, t = 13.323, all P < 0.01).RT-PCR results showed that the relative expression of Occludin mRNA was 0.000 117 ± 0.000 035 in the nasal polyp group and was significantly lower than that in the control group(0.000 464 ± 0.000 134), and the difference was significant (Z = -5.0, P < 0.01) . There was no statistically significant difference in the relative expression of Claudin-1 and ZO-1 mRNA between the nasal polyp group and the control group (P > 0.05) . After the cultured human nasal epithelial cells were stimulated by IL-13, IL-17, IFN-γ and other proinflammatory cytokines, the relative expression of Occludin mRNA was 0.631 ± 0.039, 0.581 ± 0.029 and 0.648 ± 0.040, respectively. Compared with the unstimulated control group, the differences were statistically significant (t = 16.299, 24.669 and 14.995 respectively, all P < 0.05).Western blot analyse showed that the relative grayscale in the above proinflammatory cytokines stimulation groups was 0.650 ± 0.061,0.482 ± 0.106 and 0.536 ± 0.109, respectively. Compared with the unstimulated control group, the differences were statistically significant (t = 9.880, 8.442 and 7.310 respectively, all P < 0.05).

CONCLUSIONSThe reduced expression of Occludin might be involved in the pathogenesis of nasal polyps.

Claudin-1 ; Cytokines ; Epithelial Cells ; Humans ; Interleukin-13 ; Interleukin-17 ; Nasal Mucosa ; Nasal Polyps ; metabolism ; Occludin ; genetics ; metabolism ; RNA, Messenger ; Tight Junctions ; metabolism ; Transforming Growth Factor alpha ; Zonula Occludens-1 Protein

Objective: To explore the role of TGF-β1 in the proliferation and apoptosis of Sertoli cells and its effect on the expressions of tight junction-related proteins and genes in rats. METHODS: Rat Sertoli cells were isolated in vitro, primarily cultured, and divided into groups A (blank control), B (TGF-β1 receptor blocker), C (TGF-β1), and D (TGF-β1 + receptor blocker). The proliferation and apoptosis of the cells were detected by CCK-8 and flow cytometry, respectively. After establishment of the dual-chamber model for the primary culture of Sertoli cells, the trans-epithelia electrical resistance (TER) value was measured and the relative expressions of Occludin, ZO-1 and Claudin Ⅱ determined by RT-PCR and Western blot. RESULTS: The OD value of the proliferation of the Sertoli cells was markedly higher in group C than in groups A and D (0.79 ± 0.04 vs 0.66 ± 0.05 and 0.68 ± 0.02, P<0.05), with statistically significant differences among the four groups (F = 5.05, P <0.05). However, no remarkable difference with found among the four groups in the apoptosis rate of the cells (F = 1.13, P >0.05). The TER value was dramatically decreased in group C as compared with groups A and D (［176.37 ± 16.61］ vs ［281.42 ± 9.83］ and ［254.37 ± 13.55］ /cm2, P<0.01), with statistically significant differences among the four groups (F = 38.99, P<0.01). There were no remarkable differences among the four groups in the mRNA expressions of ZO-1 and Claudin Ⅱ (F = 0.49 and 0.93, P>0.05) or their protein expressions (F = 0.28 and 1.31, P>0.05). Both the mRNA and protein expressions of Occludin were markedly lower in group C than in A and D (P<0.01 and P<0.05), with statistically significant differences among the four groups (F = 6.86 and 6.87, P<0.01). CONCLUSIONS TGF-β1 can promote the proliferation of Sertoli cells in rats and act on the tight junction of the cells by regulating the expression of Occludin.
Animals ; Apoptosis ; Cell Proliferation ; Cells, Cultured ; Claudin-2 ; metabolism ; Male ; Occludin ; metabolism ; RNA, Messenger ; Rats ; Sertoli Cells ; cytology ; physiology ; Tight Junction Proteins ; metabolism ; Tight Junctions ; genetics ; metabolism ; Transforming Growth Factor beta1 ; physiology ; Zonula Occludens-1 Protein ; metabolism

OBJECTIVETo investigate changes in the expression of tight junction (TJ) proteins in the cerebral cortex, hippocampus, heart, lung, and testes of rats after exposure to electromagnetic pulse (EMP).

METHODSEighteen adult male Sprague-Dawley rats were divided into sham and exposure groups. The exposure groups received EMP at 200 kV/m for 200 pulses with a repetition rate of 1 Hz. The expression of TJ proteins (ZO-1, occludin, actin) in the several organs was examined by western blotting.

RESULTSZO-1 levels in the cerebral cortex decreased 1 h and 3 h after EMP exposure compared with sham group (P<0.05). No significant difference was observed for occludin and actin. ZO-1 levels in the hippocampus increased 1 h and 3 h post-exposure (P<0.05), and occludin decreased after 3 h (P<0.05); however, actin was unaffected. ZO-1 levels in the heart increased 3 h post-exposure (P<0.05), occludin decreased 3 h post-exposure (P<0.05), and actin increased 1 h and 3 h post-exposure (P<0.05). ZO-1, occludin and actin levels in the lung decreased compared with those in the sham group (P<0.05). ZO-1 and occludin levels in the testes decreased 1 h and 3 h post-exposure (P<0.05), but actin showed no significant change.

CONCLUSIONExposure to EMP altered the expression levels of TJ proteins, particularly ZO-1, in the organs of adult male rats, which may induce changes in barrier structure and function.

Actins ; genetics ; metabolism ; Animals ; Cerebral Cortex ; cytology ; metabolism ; Electromagnetic Radiation ; Gene Expression Regulation ; radiation effects ; Lung ; cytology ; metabolism ; Male ; Membrane Proteins ; genetics ; metabolism ; Myocardium ; cytology ; metabolism ; Occludin ; Phosphoproteins ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Testis ; cytology ; metabolism ; Tight Junctions ; metabolism ; Zonula Occludens-1 Protein

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.
Animals ; Calcium-Binding Proteins ; metabolism ; Caspase 3 ; metabolism ; Cerebral Cortex ; pathology ; Claudin-5 ; metabolism ; Colitis ; chemically induced ; complications ; pathology ; Cytokines ; genetics ; metabolism ; Dextran Sulfate ; toxicity ; Disease Models, Animal ; Encephalitis ; etiology ; Gene Expression Regulation ; drug effects ; Mice ; Microfilament Proteins ; metabolism ; Occludin ; metabolism ; Polysaccharides ; blood ; toxicity ; Time Factors

OBJECTIVES: Because intracerebral hemorrhage (ICH) has high morbidity, disability and mortality, it is significant to find new and effective treatments for ICH. This study aims to explore the effect of butyphthalide (NBP) on neuroinflammation secondary to ICH and microglia polarization. METHODS: A total of 48 healthy male SD rats were randomly divided into 6 groups: a sham 24 h group, a sham 72 h group, an ICH 24 h group, an ICH 72 h group, an ICH+NBP 24 h group, and an ICH+NBP 72 h group (8 rats per group). After operation, the neurological deficiencies were assessed based on improved Garcia scores and corner test. The expressions of Toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), aquaporin-4 (AQP4), zonula occludens-1 (ZO-1), occludin, CD68, CD86, and CD206 were observed by Western blotting. Inflammatory cytokines were detected by ELISA. The immunofluorescence was to detect the polarization of microglia. RESULTS: 1) Compared with the sham groups, the expression of TLR4 (24 h: P<0.05; 72 h: P<0.01), NF-κB (both P<0.01) and Nrf2 (both P<0.01) in the perihematoma of the ICH group was increased, leading to microglia activation (P<0.01). The expressions of IL-6 (24 h: P<0.05; 72 h: P<0.01) and TNF-α (both P<0.01), the pro-inflammatory cytokines were up-regulated, and the expression of anti-inflammatory cytokine IL-4 was down-regulated (both P<0.01). Besides, the expression of AQP4 was enhanced (both P<0.01). The protein level of tightly connected proteins (including ZO-1, occludin) was decreased (all P<0.01). The neurological function of the rats in the ICH group was impaired in the 2 time points (both P<0.01). 2) Compared with the sham group at 24 h and 72 h after the intervention of NBP, the expressions of TLR4 (both P<0.05) and NF-κB (both P<0.01) were significantly declined, and the expression of Nrf2 was further enhanced (both P<0.05) in the perihematoma of the ICH+NBP group. Furthermore, the expression of M1 microglia marker was inhibited (P<0.05), and the polarization of microglia to the M2 phenotype was promoted (P<0.01). 3) In terms of inflammation after ICH, the IL-4 expression in the ICH+NBP group was increased compared with the ICH group (24 h: P<0.05; 72 h: P<0.01); the expression of IL-6 was decreased significantly in the ICH+NBP 72 h group (P<0.01); the level of AQP4 was declined significantly in the ICH+NBP 24 h group (P<0.05), there was a downward trend in the 72-hour intervention group but without significant statistical difference. 4) Compared with the ICH group, the ZO-1 protein levels were increased (24 h: P<0.05; 72 h: P<0.01), and the symptoms of nerve defect were improved eventually (both P<0.05) in the ICH+NBP groups. CONCLUSIONS After ICH, the TLR4/NF-κB pathway is activated. The M1 microglia is up-regulated along with the release of detrimental cytokines, while the anti-inflammatory cytokines are down-regulated. The expression of AQP4 is increased, the tight junction proteins from the blood-brain barrier (BBB) is damaged, and the neurological function of rats is impaired. On the contrary, NBP may regulate microglia polarization to M2 phenotype and play a role in the neuroprotective effect mediated via inhibiting TLR4/NF-κB and enhancing Nrf2 pathways, which relieves the neuroinflammation, inhibits the expression of AQP4, repairs BBB, and improves neurological functional defects.
Animals ; Anti-Inflammatory Agents/therapeutic use* ; Cerebral Hemorrhage ; Cytokines/metabolism* ; Interleukin-4/therapeutic use* ; Interleukin-6/metabolism* ; Male ; Microglia/metabolism* ; NF-E2-Related Factor 2/metabolism* ; NF-kappa B/metabolism* ; Occludin/pharmacology* ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; Toll-Like Receptor 4/genetics*