Ying-ying Chen

Puerarin protects against high glucose-induced acute vascular dysfunction: role of heme oxygenase-1 in rat thoracic aorta.

OBJECTIVE To investigate the antioxidant and vascular protective effect of puerarin, an isoflavone glycoside known in traditional Chinese medicine on vascular reactivity subsequent to high glucose stress. METHODS The thoracic aortic rings with or without endothelium from male SD rats were mounted in an organ bath. Isometric contraction of aortic rings was measured. HO-1 protein expression and HO activity were also evaluated. RESULTS (1) After incubation with 44 mmol/L of high glucose for 2 or 4 h, the vascular contraction responses to phenylephrine (PE) and relaxation response to acetylcholine (Ach) decreased in an endothelium-dependent manner; (2) Coincubation with puerarin (10(-10)-10(-8) mol/L) and high glucose, the high glucose-induced vasoconstriction and vasodilation dysfunction was partly inhibited in a dose-dependent manner; (3) Puerarin increased the HO-1 protein expression and HO activity of thoracic aorta. ZnPP (an inhibitor of heme oxygenase-1) offset the protective effect of puerarin. CONCLUSION Puerarin could alleviate the high glucose-induced acute endothelium-dependent vascular dysfunction in rat aortic rings. HO-1 activity was proposed as a mechanism to account for the protection of vascular responses by puerarin.

Protective effects of the aqueous extract of Scutellaria baicalensis against acrolein-induced oxidative stress in cultured human umbilical vein endothelial cells

Context: Scutellaria baicalensis Georgi (Labiatae) (SbG), one of the fifty fundamental herbs of Chinese herbology, has been reported to have anti-asthmatic, antifungal, antioxidative, and anti-inflammatory activities. Objective: This study was designed to determine the protective effects of the extract of SbG against the acrolein-induced oxidative stress in cultured human umbilical vein endothelial cells (HUVEC). Materials and methods: The MTT reduction assay was employed to determine cell viability. The total cellular glutathione (GSH) level was detected using a colorimetric GSH assay kit. Cellular GSH production was conducted by detecting the mRNA expression levels of γ-glutamylcysteine ligase catalytic subunit and modifier subunit. Results: Concentration-dependent cytotoxic effects of acrolein were observed while SbG could effectively protect the acrolein-induced oxidative damage. The protective mechanism was investigated, showing that the increased GSH content in the SbG-incubated HUVE cells was associated with the protective effects of SbG-treated cells. Further RT-PCR data confirmed the elevated mRNA expressions of GSH synthesis enzymes. Discussion and conclusion: The current study strongly indicated that SbG could be a potential antioxidant against oxidative stress in treating cardiovascular diseases.

Heat shock protein 90 mediates anti-apoptotic effect of diazoxide by preventing the cleavage of Bid in hypothermic preservation rat hearts

BACKGROUND Successful organ preservation is the premise for clinical organ transplantation. The present study investigated whether heat shock protein 90 (Hsp90) is important in the anti-apoptotic effect of diazoxide in hypothermic preservation rat hearts. METHODS Isolated rat hearts were preserved in Celsior solution, with or without diazoxide, for 3 to 9 hours, followed by 60 minutes of reperfusion. Cell apoptosis was assessed by terminal deoxynucleotide transferase-mediated deoxy uridine triphosphate nick-end labeling. The left ventricular developed pressure (LVDP) was recorded. Expression of Hsp90 protein and cleavage of Bid were detected by Western blot and polymerase chain reaction. RESULTS After hypothermic preservation for 3 to 9 hours, the LVDP recovery rate significantly decreased and cardiomyocyte apoptosis index increased in a time-dependent manner. When compared with the 9-hour preservation group, Celsior solution supplemented with diazoxide significantly enhanced the LVDP recovery rate and decreased the apoptosis index. The cleavage of Bid increased after 9 hours of hypothermic preservation, which was inhibited by Celsior solution supplemented with diazoxide. Hypothermic preservation of rat hearts for 9 hours decreased the expression of Hsp90, whereas diazoxide supplementation significantly increased the expression of Hsp90. The Hsp90 inhibitor 17-allylamino-17-demethoxy-geldanamycin inhibited the diazoxide-induced decrease in cleavage of Bid, improvement of cardiac function, and decrease of apoptosis. Hsp90 inhibitor had no effect on the diazoxide-induced increase of total Cx43 protein expression in hearts preserved 9 hours, but inhibited the diazoxide-induced increase of mitochondrial Cx43 protein level. CONCLUSION Hsp90 might mediate diazoxide-induced cardioprotection against apoptosis in hypothermic preservation heart by preventing the cleavage of Bid.

Induction of heme oxygenase-1 ameliorates vascular dysfunction in streptozotocin-induced type 2 diabetic rats.

AIMS To explore the effects of heme oxygenase-1 (HO-1) on vascular dysfunction in high fat diet streptozotocin-induced type 2 diabetic (T2D) rats. METHODS Rats received a high-fat diet followed by a low dose of streptozotocin (30 mg/kg) to induce T2D. T2D rats were treated with hemin (1, 5, or 25mg/kg) or carbon monoxide-releasing molecule-2 (CORM-2, 5 mg/kg) for 4 weeks. Isometric contractions of aortic rings were measured. The expression of cyclooxygenase-2 (COX-2) and activities of HO, SOD, and MDA were evaluated. RESULTS The fasting blood glucose, blood insulin levels, and IR index in T2D rats were higher than those in the control group, which were ameliorated by HO-1 inducer hemin. The antidiabetic effect was accompanied by enhanced HO activity. The vascular relaxation response to ACh was decreased in T2D rats, while treatment with hemin could prevent such decrease in vasorelaxation. An increase in COX-2 expression was found in the aortas of T2D rats. Treatment of T2D rats with COX-2 inhibitor NS398 restored ACh-induced vasodilation. COX-2 overexpression in T2D rats was inhibited by hemin. Hemin treatment also inhibited the decline of SOD activity and the increase of MDA content in the aorta of T2D rats. CORM-2, an agent which releases the HO-1 product CO, could mimic the beneficial effect of hemin. CONCLUSION Induction of HO-1 with hemin ameliorates the abnormality of endothelium-dependent vascular relaxation in T2D rats. A possible mechanism involves suppression of reactive oxygen species production and inhibition of COX-2 up-regulation induced by diabetes mellitus.

CURCUMIN AMELIORATES HIGH GLUCOSE-INDUCED ACUTE VASCULAR ENDOTHELIAL DYSFUNCTION IN RAT THORACIC AORTA

1 The aims of the present study were to explore the protective effect of curcumin against the acute vascular endothelial dysfunction induced by high glucose and to investigate the possible role of heme oxygenase (HO)‐1 in this protective action. 2 Thoracic aortic rings, with or without endothelium, obtained from male Sprague‐Dawley rats were mounted in an organ bath. Isometric contraction of the rings was recorded. After completion of the organ bath studies, rings were homogenized and centrifuged (30 000 g, 4°C, 15 min) and HO activity was determined in the supernatant. 3 After 2 h incubation of aortic rings in the presence of high glucose (44 mmol/L), the relaxation evoked by acetylcholine (3 × 10−8 to 3 × 10−5 mol/L) was significantly decreased only in rings with an intact endothelium. When rings were coincubated in the presence of curcumin (10−13 to 10−11 mol/L) and high glucose, curcumin reversed the vasodilator dysfunction induced by high glucose dose dependently. 4 Curcumin (10−11 mol/L) increased HO activity in the aortic rings compared with activity in control rings (63.1 ± 3.6 vs control 43.2 ± 2.9 pmol/mg per h, respectively; P < 0.01). Protoporphyrin IX zinc (10−6 mol/L), an inhibitor of HO‐1, offset the protective effects of curcumin. In addition, the non‐selective guanylate cyclase (GC) inhibitor methylene blue (10−6 mol/L) completely abolished the protective effects of curcumin. 5 In conclusion, the results of the present study show that curcumin alleviates the acute endothelium‐dependent vasodilator dysfunction induced by high glucose in rat aortic rings. Increased HO‐1 activity and stimulation of GC may be involved in the protective effects of curcumin.

Enhancement of lipopolysaccharide-induced toll-like receptor 2 expression and inflammatory cytokine secretion in HUVECs under high glucose conditions

AIMS Endothelial inflammatory responses mediated by toll-like receptors (TLRs) play an important role in atherogenesis. We aimed to investigate the exacerbation of an inflammatory response in human umbilical vein endothelial cells (HUVECs) under high glucose conditions. MAIN METHODS HUVECs were exposed to normal glucose (5.5 mmol/L) and high glucose (25, 50 mmol/L), alone or with lipopolysaccharide (LPS 0, 10, 100, or 1000 μg/L). Then concentrations of TNF-α and IL-6 in the culture supernatants were determined. The expression of toll-like receptor 2 (TLR2), TLR4 and NF-κB was evaluated by Western blot and RT-PCR analysis. KEY FINDINGS Compared with the normal glucose group, exposure of HUVECs to 50 mmol/L of glucose or 1000 μg/L of LPS significantly increased the concentrations of TNF-α and IL-6 in the culture supernatants. Neither 25 mmol/L of glucose nor low concentration of LPS (≤100 μg/L) alone had an effect on TNF-α and IL-6 release, or TLR2 expression, but they stimulated the inflammatory response and TLR2 expression under high glucose conditions (25 mmol/L) in combination. LPS (100 μg/L) did not alter the TLR4 expression in HUVECs under high glucose condition. Co-incubation with glucose and LPS increased the nuclear NF-κB expression in endothelial cells. Both NF-κB inhibitor and ROS scavenger could inhibit the enhancement of LPS-induced TLR2 expression and inflammatory cytokine secretion under high glucose conditions. SIGNIFICANCE We show in vitro data on the potential role of high glucose in increasing LPS-induced TLR2 expression and inflammatory cytokine secretion in HUVECs, offering a new insight into the pathophysiological pathways involved in atherosclerosis.

Puerarin protects human umbilical vein endothelial cells against high glucose-induced apoptosis by upregulating heme oxygenase-1 and inhibiting calpain activation.

The aim of this study was to investigate whether puerarin protects against high glucose (HG)‐induced apoptosis by suppressing calpain activation in human umbilical vein endothelial cells (HUVECs). HUVECs were exposed to normal glucose (NG) (5.5 mm) or HG (33 mm) for 48 h; then, apoptosis and caspase‐3 activity were determined. The expression of heme oxygenase‐1 (HO‐1) mRNA was evaluated by RT‐PCR analysis. The activation of calpain and HO activity were also assessed. Compared with the NG group, exposure of HUVECs to HG for 48 h resulted in significant increases in calpain and caspase‐3 activity as well as apoptosis, which were prevented by co‐incubation with puerarin (1–100 μm) in a concentration‐dependent manner. HO‐1 mRNA expression and HO activity were decreased in HUVECs treated with HG for 48 h. Compared with the group exposed to HG alone, co‐incubation of HUVECs with puerarin and HG induced increases in HO‐1 mRNA expression and HO activity. The HO‐1 inhibitor protoporphyrin IX zinc (II) abolished the inhibitory effect of puerarin on HG‐induced calpain and caspase‐3 activation, as well as apoptosis. The data show that puerarin protects against HG‐induced endothelial cell apoptosis by a mechanism involving upregulation of HO‐1 expression and inhibition of calpain activity.

Bone marrow mesenchymal stem cells decrease CHOP expression and neuronal apoptosis after spinal cord injury

Spinal cord injury (SCI) leads to irreversible neuronal loss and ultimately leads to paralysis. Bone marrow derived mesenchymal stem cells (BMSCs) have been demonstrated to be an effective approach to treat SCI. The present study was designed to investigate the role of BMSCs in rats with spinal cord injury and in oxygen-glucose deprivation (OGD) treated motor neurons. The results demonstrated that BMSCs could improve locomotor function and decrease expression of pro-apoptotic transcription factor C/EBP homologous protein (CHOP) and apoptosis after SCI. Furthermore, co-culture with BMSCs or conditioned medium from BMSCs could also decrease the expression of CHOP and apoptosis in post-OGD motor neurons, supporting that BMSCs exerts protective effects by decreasing the expression of CHOP in injured motor neurons. Our findings provide a potential novel mechanism for BMSCs treatments in patients with SCI.

Lipopolysaccharide pretreatment promotes cardiac stem cell migration through heat shock protein 90-dependent β-catenin activation

AIMS To investigate the effect of lipopolysaccharide (LPS) on the migration of cardiac stem cells (CSCs) and whether β-catenin is involved in its underlying mechanism. MAIN METHODS CSCs were isolated from neonatal Sprague-Dawley rat hearts. Migration was detected using 24-well transwell system in vitro cultured CSCs and using carboxyfluorescein diacetate (CFDA)-labelled method in myocardial infarction rat model. The expression of toll like receptor 4 (TLR4), β-catenin, heat shock protein 90 (HSP90) was analyzed using western blotting. KEY FINDINGS Exposure of CSCs to higher LPS (1μg/mL) for 24h inhibited the cell migration. However, LPS (0.01, 0.1μg/mL) significantly increased the number of migrated CSCs, which reached a peak at 0.01μg/mL. LPS (0.01μg/mL) pretreatment promoted the migration of CFDA-labeled CSCs into the risk area in ischemia-reperfusion rat heart. And injection of LPS-pretreated CSCs also caused a significant decrease in infarct size when compared with LPS-untreated CSCs group. Lower dose of LPS did not influence the expression of TLR4 and total β-catenin protein. However, it enhanced the levels of active β-catenin, nuclear β-catenin, and HSP90 protein. Compared with LPS group, after preincubated with HSP90 inhibitor 17-AAG, the LPS-induced enhancement of active β-catenin protein and nuclear β-catenin protein was abolished. In addition, 17-AAG also prevented the lower dose of LPS-induced cell migration. SIGNIFICANCE The results suggested that low dose of LPS pretreatmemt induced increased CSC migration, reduced the infarct size of ischemia-reperfusion heart. The mechanism might be due to the activation and translocation of β-catenin via HSP90-dependent manner.

Diazoxide supplemented Celsior solution improves hypothermic heart preservation effect in rat through activation of mitochondrial ATP-sensitive potassium channel

Successful heart preservation is critical for clinical heart transplantation, but even the most successful heart preservation method can only preserve the heart in a time range of approximately 4 h. In the present study, diazoxide (DE)-containing cardioplegia solution was used as the hypothermic heart preservation solution, and hearts were preserved for different time periods before reperfusion. Five groups were randomly divided into the control group, DE groups with different concentrations of DE (15, 30, and 45 μM), and the 5-HD + DE group containing 30 μM DE and 100 μM of 5-hydroxydecanoate (5-HD). Each group was further divided according to the storage time: 3 h and 8 h subgroups. Hemodynamic parameters were monitored continually and myocardial injury markers lactate dehydrogenase (LDH) and creatine kinase (CK) were measured before arrest and during reperfusion. After reperfusion, myocardium water content, myocardium apoptosis, and myocardial mitochondrial superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were measured. All data were analyzed by independent samples t-test. Our results showed that diazoxide treatment improved impaired hemodynamics parameters and decreased the leakage of myocardial enzymes during reperfusion, compared to the control group. Moreover, diazoxide treatment significantly alleviated myocardial edema, decreased the number of TUNEL-positive cardiomyocytes, prevented the loss of mitochondrial SOD activity, and depressed the mitochondrial MDA content. This study indicated that mitoKATP channel opener diazoxide could significantly enhance myocardial protection during long-term hypothermic preservation, and the inhibition of oxidative stress-induced myocardium apoptosis seems to be the mechanism involved in the protective action on the mitoKATP channel.