Liang-Yi Si

Resveratrol prevents hyperglycemia-induced endothelial dysfunction via activation of adenosine monophosphate-activated protein kinase

Endothelial dysfunction secondary to persistent hyperglycemia plays a key role in the development of type 2 diabetic vascular disease. The aim of the present study was to examine the protective effect of resveratrol against hyperglycemia-induced endothelial dysfunction. In cultured human umbilical vein endothelial cells (HUVECs), resveratrol (10-100 microM) concentration dependently enhanced phosphorylation of endothelial nitric oxide synthesis (eNOS) at Ser1177 and nitric oxide (NO) production. In addition, resveratrol can increase the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) at Thr172 and suppress high glucose-induced generation of superoxide anion. In mouse aortic rings, resveratrol (1-100 microM) elicited endothelium-dependent vasodilatations and alleviated high glucose-mediated endothelial dysfunction. All these beneficial effects of resveratrol on the endothelium were abolished by pharmacological antagonism of AMPK by compound C. These results provide new insight into the protective properties of resveratrol against endothelial dysfunction caused by high glucose, which is attributed to the AMPK mediated reduction of superoxide level.

Induction of Oxidative stress by Oxidized LDL via Meprinα–Activated Epidermal Growth Factor Receptor in Macrophages

AIMS The aim of this study was to explore meprinα-mediated transactivation of the epidermal growth factor receptor (EGFR) and reactive oxygen species (ROS) production in macrophages. METHODS AND RESULTS Accelerated atherosclerotic lesions were established by administration of a high-fat diet in apolipoprotein E-deficient (apoE(-/-)) mice. Lentiviral overexpression of meprinα in the thoracic aortic artery during plaque formation enhanced intra-plaque macrophage induction of ROS as well as formation of atherosclerotic plaques, whereas AG1478 (specific inhibitor of the EGFR) treatment exerted the opposite effect. A meprinα inhibitor abrogated EGFR activation in mice. In cultured J774a.1 macrophages, oxidized low-density lipoprotein (OxLDL) increased ROS formation and EGFR activation through a ligand [heparin-binding epidermal growth factor-like growth factor (HB-EGF)]-dependent pathway. However, a meprinα inhibitor or specific siRNA inhibited ROS production and EGFR activation. Recombinant mouse meprinα enhanced OxLDL-stimulated production of ROS and induced HB-EGF. Inhibition of p38 mitogen-activated protein kinase by SB203580 decreased OxLDL-stimulated production of ROS. Conversely, inhibition of meprinα or PI3K-Rac1 inhibitors also decreased p38 activity in OxLDL-stimulated macrophages. In addition, inhibition of meprinα reversed OxLDL-stimulated activation of PI3K. CONCLUSION Meprinα promotes OxLDL-induced plaque formation and ROS release by transactivation of the EGFR, followed by activation of the PI3K/Rac1/p38 pathway.

Fibroblast Growth Factor 21 Protects Against High Glucose Induced Cellular Damage and Dysfunction of Endothelial Nitric-Oxide Synthase in Endothelial Cells

Aims: Fibroblast growth factor 21 (FGF21) is a powerful endocrine hormone modulating glucose and lipid metabolism and represents a promising drug for type 2 diabetes. The present study was to determine the effect of FGF21 on high glucose-induced damage and dysfunction in endothelial cells. Methods: The protein expression of β-klotho was examined in human umbilical vein endothelial cell (HUVECs) using immunofluorescence and Western blotting. HUVECs were cultured in medium with normal glucose (NG), high glucose (HG) and HG + FGF21 (30 nM). Cell viability, migration, reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase, nitric oxide (NO) production, intracellular cyclic guanosine monophosphate (cGMP) and endothelial nitric oxide synthase (eNOS) phosphorylation at Ser-1177/Ser-633 sites were measured. Results: β-klotho, the anchor protein of FGF21, is expressed in HUVECs. Administration of FGF21 prevented HG-induced impairment of cell viability, migration, oxidant stress, NO production and intracellular cGMP levels in HUVECs. FGF21 also rescued HG-induced decrease of eNOS phosphorylation at Ser-1177 and Ser-633. HG and FGF21 had no effects on eNOS phosphorylation at Ser-617 and Thr-495. Inhibition of AMP-activated protein kinase (AMPK), but not Akt or Ca2+/calmodulin-dependent protein kinase II, abolished the protective effect of FGF21 on eNOS phosphorylation at Ser-1177. The protective effect of FGF21 on eNOS phosphorylation at Ser-633 was also abolished by inhibition of AMPK but not by Akt or cAMP-dependent protein kinase A. Conclusion: Our results provide the first evidence that FGF21 protects against high glucose induced cell damage and eNOS dysfunction in an AMPK-dependent manner in HUVECs, and suggest that FGF21 may be a promoting therapeutic agent for vascular complications in diabetes.

A potential regulatory single nucleotide polymorphism in the promoter of the Klotho gene may be associated with essential hypertension in the Chinese Han population

BACKGROUND Mice with defects in the Klotho gene exhibit multiple aging phenotypes including arteriosclerosis. We hypothesised that the G-395A polymorphism in the promoter region of the human Klotho gene may contribute to the prevalence of Essential Hypertension (EH). METHODS We investigate whether the G-395A polymorphism of Klotho is associated with EH in a population consisting of 215 patients with EH and 220 non-hypertensive subjects. We also tested whether a G/A substitution at the G-395A site affected the transcription level in vitro through the dual-luciferase reporter assay. RESULTS Differences in the genotype distributions of the G-395A polymorphism between the EH and non-hypertension groups are statistically significant (P=0.032). There are differential effects of age, gender and smoking status on the association of the G-395A polymorphism with EH; the G-395A polymorphism is significantly associated with EH in subjects over 60years old, in females and in nonsmokers. A multiple logistic regression analysis indicated that the odds ratio for EH in the -395A allele carriers as compared with the control group was 0.593 (P=0.024) after adjusting for current traditional risk factors. The dual-luciferase reporter assay revealed that the -395A carrier of a 498-bp DNA fragment (containing the G-395A site) upstream of the Klotho gene has higher relative luciferase activity than the -395G carrier. CONCLUSIONS The G-395A polymorphism of the human Klotho gene is associated with EH and may be a potential regulatory site.

Protective effect of tetramethylpyrazine isolated from Ligusticum chuanxiong on nephropathy in rats with streptozotocin-induced diabetes

PURPOSE This study was designed to investigate the protective effect of tetramethylpyrazine isolated from Ligusticum chuanxiong, a traditional Chinese medicine, on diabetic nephropathy in a rat model, and to explore the possible mechanism involved in a protective function. MATERIALS Diabetes was induced in male Sprague-Dawley rats by a single intraperitoneal injection of 70mg/kg of streptozotocin. One week later, 200mg/kg/day of tetramethylpyrazine was administered intragastric gavage daily for 8 weeks. Renal functions and expression of vascular endothelial growth factor were examined at 4 and 8 weeks after tetramethylpyrazine administration. RESULTS Blood glucose and renal function were significantly improved in the tetramethylpyrazine-treated group compared to the untreated diabetic rats. Diabetic nephropathy resulted in an increase in the expression of vascular endothelial growth factor, while tetramethylpyrazine administration greatly decreased the expression. CONCLUSIONS Our results suggest that administration of tetramethylpyrazine may reduce kidney damage caused by diabetes. This protective effect may be mediated, in part, by downregulated expression of vascular endothelial growth factor in the kidney.

FGF21 represses cerebrovascular aging via improving mitochondrial biogenesis and inhibiting p53 signaling pathway in an AMPK-dependent manner.

Cerebrovascular aging has a high relationship with stroke and neurodegenerative disease. In the present study, we evaluated the influence of fibroblast growth factor 21 (FGF21) on angiotensin (Ang II)-mediated cerebrovascular aging in human brain vascular smooth muscle cells (hBVSMCs). Ang II induced remarkable aging-phenotypes in hBVSMCs, including enhanced SA-β-gal staining and NBS1 protein expression. First, we used immunoblotting assay to confirm protein expression of FGF21 receptor (FGFR1) and the co-receptor β-Klotho in cultured hBVSMCs. Second, we found that FGF21 treatment partly prevented the aging-related changes induced by Ang II. FGF21 inhibited Ang II-enhanced ROS production/superoxide anion levels, rescued the Ang II-reduced Complex IV and citrate synthase activities, and suppressed the Ang II-induced meprin protein expression. Third, we showed that FGF21 not only inhibited the Ang II-induced p53 activation, but also blocked the action of Ang II on Siah-1-TRF signaling pathway which is upstream factors for p53 activation. At last, either chemical inhibition of AMPK signaling pathway by a specific antagonist Compound C or knockdown of AMPKα1/2 isoform using siRNA, successfully abolished the anti-aging action of FGF21 in hBVSMCs. These results indicate that FGF21 protects against Ang II-induced cerebrovascular aging via improving mitochondrial biogenesis and inhibiting p53 activation in an AMPK-dependent manner, and highlight the therapeutic value of FGF21 in cerebrovascular aging-related diseases such as stroke and neurodegenerative disease.

Transendocardial delivery of HGF via microbubbles and ultrasound to treat acute myocardial infarction.

To enhance the safety of transendocardial delivery and the efficacy of intramyocardial angiogenic gene expression, a visible, less invasive, targeted, high-efficiency gene delivery strategy was tested. Progress toward clinical approval of systemic administration of genes and microbubbles (MBs) has been limited. The feasibility of transendocardially delivering MBs as extracellular markers and gene carriers in conjunction with intracardiac ultrasound (US) treatment remains unknown. In a canine acute myocardial infarction (MI) model, a naked plasmid encoding 500 μg human hepatocyte growth factor (HGF) was delivered transendocardially to the myocardium via US/MB (HGF-US/MB), insonation (HGFUS), or alone (HGF alone). Control MI dogs received saline without US/MB (control group). During US/MB, intracardiac insonation was performed for 30 s with a 10-s pause, at 4.3-MHz, 1-W/cm(2), for 60 s at each site. Gene and MB distribution in the myocardium was visualized. Compared to the HGF alone group at 28 days, the HGF-US/MB group had an average 7.1-fold enhancement in gene expression (P < 0.01). Compared to the control group, there were 16% decreases in the ratio of left ventricle (LV) weight/body weight in the HGF-US/MB group and decreases in collagen volume fraction (CVF) of type I (33%) and type III (23%) collagen. Capillary density increased from 22.8 ± 6.3/mm(2) in the control group to 154.3 ± 42.9/mm(2) in the HGF-US/MB group (P < 0.01). This less invasive catheter-based US therapeutic procedure offers observable gene delivery with higher therapeutic efficiency, enhanced angiogenesis, and improved myocardial perfusion and ventricular function following MI.

Antigen-specific Immunotherapy Regulates B Cell Activities in the Intestine

Background: B cells play an important role in allergic diseases. Results: Lower doses of antigen induce BCs to produce IL-10; higher doses result in high serum levels of soluble CD23. Conclusion: Exposure to lower doses of antigen induces B cells to inhibit skewed Th2 responses. Significance: Optimal dosage of antigen in specific antigen vaccination determines the clinical outcomes. Mature B cells (BCs) express CD23 and B cell receptors. Whether activation of CD23 and B cell receptors has different effects on BC activities is unclear. This study aims to investigate the mechanism by which the specific antigen immunotherapy regulates the activation of BCs in the skewed Th2 responses. Mice were sensitized to ovalbumin. The specific antigen vaccination (SAV) at graded doses was employed to modulate the activities of BCs in which the expression of IL-10, IgE, matrix metalloproteinase-9 (MMP9), CD23, and serum soluble CD23 by BCs was evaluated. The immune regulatory effect of BCs primed by lower or higher SAV doses was observed with an adoptive transfer mouse experiment. SAV activated CD23 to produce IL-10 in BCs at lower doses. The higher doses of SAV increased the expression of MMP9 in BCs that reduced the amounts of CD23 in BCs and increased the serum levels of soluble CD23, which was abrogated by the pretreatment with MMP9 inhibitor. Adoptively transfer with BCs primed by lower doses of SAV inhibited the ongoing antigen-specific Th2 responses whereas the BCs primed by higher doses of SAV exacerbated the ongoing Th2 responses. Exposure to specific antigens at optimal doses can activate BCs to produce IL-10 to suppress the skewed antigen-specific Th2 responses. The antigen doses of SAV higher than the optimal doses may promote the production of soluble CD23 to exacerbate the ongoing immune responses.

A transendocardial delivery and intracardiac ultrasound irradiation treatment catheter.

Abstract Objectives: This study introduces the structural design, working principles, performance testing and treatment effects of a newly developed ultrasonic irradiation delivery and treatment catheter system that integrates interventional catheterization technology. Background: Systemic administration method needs a high dose of gene and induces side effect of non-target organ delivery. Direct intramyocardial injection of a low-dose angiogenic gene followed by insonation treatment can enhance gene expression. So, a novel transendocardial gene delivery and intracardiac ultrasound irradiation strategy was tested. Methods: The medical interventional ultrasonic therapeutic apparatus is comprised of an ultrasonic irradiation catheter and a host. The ultrasonic irradiation catheter, which is equipped with an advance-and-retreat convenient miniature syringe needle and a miniature piezoelectric transducer on the tip, was used. Twelve dogs were divided into three groups: (1) EGFP and US (EGFP + US), (2) EGFP alone and (3) control group. In the EGFP + US group, EGFP plasmid DNA (500 µg) was injected and followed by intracardiac insonation. In the EGFP alone group, EGFP plasmid DNA (500 µg) was injected without insonation. In the control group, saline was injected. Results: The catheter can enter the heart through percutaneous intervention to realize intramyocardial injection, directly irradiate cardiac muscular tissues at close range and correctly control the ultrasonic irradiation energy delivered to cardiac muscular tissues. Compared with the EGFP gene group, an average sixfold enhancement in gene expression was achieved in the EGFP EGFP + US group (p < 0.05). Conclusions: The experimental results confirmed that the treatment catheter was safe and reliable, which can realize transendocardial intramyocardial gene injection in the left ventricular chamber, and the ultrasonic parameter can increase gene expression after intracardiac ultrasonic irradiation. The intracardiac ultrasound irradiation treatment catheter may be a useful delivery and therapy tool in the future.

Association Between Serum Cystatin C and High Blood Pressure (HBP): A Cross-Sectional Study of an Elder Chinese Type 2 Diabetic Population.

BACKGROUND The aim of this study was to investigate the relationship between serum CysC levels and high blood pressure (HBP) and to explore its diagnostic value for HBP in elder type 2 diabetic (T2D) population. METHODS A total of 369 elder T2D patients (age > 60) were included in this cross-sectional study. Their clinical and biochemical characteristics were detected. Patients were divided into two groups: with HBP and without. The risk factors of HBP were explored by binary logistic regression analysis. RESULTS The serum concentrations of CysC were 1.08 ± 0.42 and 0.90 ± 0.21 mg/L in patients with and without HBP, respectively. Binary logistic regression analysis showed that the significant risk factors were CysC (p = 0.000, OR = 16.977), systolic blood pressure (p = 0.000, OR = 1.087), and diabetes duration (p = 0.000, OR = 1.289). The prevalence of HBP increased with CysC (p < 0.05), and the prevalence of HBP in patients with CysC ≥ 1.2 mg/L was much higher than the other three quartile groups. The risk of HBP dramatically increased in patients with cystatin C ≥ 1.2 mg/L (OR = 1.601, 95% confidence interval 1.239 - 2.069, p = 0.000). After adjusting for gender, age, and diabetes duration, its OR still remained 1.633 (95% confidence interval 1.181 - 2.257, p = 0.003). CONCLUSIONS There was a strong and independent association between CysC and HBP in elder diabetic population, and cystatin C ≥ 1.2 mg/L indicated a great increased risk of HBP.