Maladaptive arterial remodeling with systemic hypertension associated with increased concentrations in blood of plasminogen activator inhibitor type-1 (PAI-1)

Cerebrovascular gene expression in spontaneously hypertensive rats

Hypertension is a hemodynamic disorder and one of the most important and well-established risk factors for vascular diseases such as stroke. Blood vessels exposed to chronic shear stress develop structural changes and remodeling of the vascular wall through many complex mechanisms. However, the molecular mechanisms involved are not fully understood. Hypertension-susceptible genes may provide a novel insight into potential molecular mechanisms of hypertension and secondary complications associated with hypertension. The aim of this exploratory study was to identify gene expression differences in the middle cerebral arteries between 12-week-old male spontaneously hypertensive rats and their normotensive Wistar-Kyoto rats using an Affymetrix whole-transcriptome expression profiling. Quantitative PCR and western blotting were used to verify genes of interest. 169 genes were differentially expressed in the middle cerebral arteries from hypertensive compared to normotensive rats. The gene expression of 72 genes was decreased and the gene expression of 97 genes was increased. The following genes with a fold difference ≥1.40 were verified by quantitative PCR; Postn, Olr1, Fas, Vldlr, Mmp2, Timp1, Serpine1, Mmp11, Cd34, Ptgs1 and Ptgs2. The gene expression of Postn, Olr1, Fas, Vldlr, Mmp2, Timp1 and Serpine1 and the protein expression of LOX1 (also known as OLR1) were significantly increased in the middle cerebral arteries from spontaneously hypertensive rats compared to Wistar-Kyoto rats. In conclusion, the identified genes in the middle cerebral arteries from spontaneously hypertensive rats could be possible mediators of the vascular changes and secondary complications associated with hypertension. This study supports the selection of key genes to investigate in the future research of hypertension-induced end-organ damage.

A Randomized Controlled Trial Comparing the Effects of Sitagliptin and Glimepiride on Endothelial Function and Metabolic Parameters: Sapporo Athero-Incretin Study 1 (SAIS1)

Objectives

The DPP-4 inhibitors are incretin-related drugs that improve hyperglycemia in a glucose-dependent manner and have been reported to exert favorable effects on atherosclerosis. However, it has not been fully elucidated whether DPP-4 inhibitors are able to improve endothelial function in patients with type 2 diabetes. Therefore, we investigated the efficacy of sitagliptin, a DPP-4 inhibitor, on endothelial function and glycemic metabolism compared with that of the sulfonylurea glimepiride.

Materials and Methods

In this multicenter, prospective, randomized parallel-group comparison study, 103 outpatients with type 2 diabetes (aged 59.9 ± 9.9 years with HbA1c levels of 7.5 ± 0.4%) with dietary cure only and/or current metformin treatment were enrolled and randomly assigned to receive sitagliptin or glimepiride therapy once daily for 26 weeks. Flow-mediated dilation (FMD), a comprehensive panel of hemodynamic parameters (Task Force^® Monitor), and serum metabolic markers were assessed before and after the treatment.

Results

During the study period, no statistically significant change in %FMD was seen in both groups (sitagliptin, 5.6 to 5.6%; glimepiride, 5.6 to 6.0%). Secretory units of islets in transplantation, TNF-α, adiponectin and biological antioxidant potential significantly improved in the sitagliptin group, and superoxide dismutase also tended to improve in the sitagliptin group, while improvements in HbA1c levels were similar between groups. Cardiac index, blood pressure and most other metabolic parameters were not different.

Conclusions

Regardless of glycemic improvement, early sitagliptin therapy did not affect endothelial function but may provide favorable effects on beta-cell function and on inflammatory and oxidative stress in patients with type 2 diabetes without advanced atherosclerosis.

Trial Registration

UMIN Clinical Trials Registry System UMIN 000004955

Aortic Remodelling Is Improved by 2,3,5,4'-Tetrahydroxystilbene-2-O-β-D-glucoside Involving the Smad3 Pathway in Spontaneously Hypertensive Rats

Hypertension is a common health problem that substantially increases the risk of cardiovascular disease. The condition increases blood pressure, which causes alterations in vascular structure and leads to the development of vascular pathologies. 2,3,5,4′-Tetrahydroxystilbene-2-O-β-D-glucoside (THSG), a resveratrol analogue extracted from a Chinese medicinal plant, has been proven to have numerous vascular protection functions. This study investigated whether THSG can improve vascular remodeling, which has thus far remained unclear. Orally administering THSG to spontaneously hypertensive rats (SHRs) aged 12 weeks for 14 weeks significantly inhibited intima-media thickness in the lower parts of the aortic arch, increased the vascular diastolic rate in response to acetylcholine, and reduced remodelling-related mRNA expression, such as that of ACTA2, CCL3, COL1A2, COL3A1, TIMP1 WISP2, IGFBP1, ECE1, KLF5, MYL1 BMP4, FN1, and PAI-1. Immunofluorescence staining also showed an inhibitory effect similar to that of THSG on PAI-1 protein expression in rat aortas. Results from immunoprecipitation and a Western blot assay showed that THSG inhibited the acetylation of Smad3. A chromatin immunoprecipitation assay showed that THSG prevented Smad3 binding to the PAI-1 proximal promoter in SHR aortas. In conclusion, our results demonstrated that the inhibitory effect of THSG on aortic remodelling involved the deacetylating role of Smad3 with increasing blood flow and with constant blood pressure.

A Comparison of the Effects of the GLP-1 Analogue Liraglutide and Insulin Glargine on Endothelial Function and Metabolic Parameters: A Randomized, Controlled Trial Sapporo Athero-Incretin Study 2 (SAIS2)

Objectives

GLP-1 improves hyperglycemia, and it has been reported to have favorable effects on atherosclerosis. However, it has not been fully elucidated whether GLP-1 is able to improve endothelial function in patients with type 2 diabetes. Therefore, we investigated the efficacy of the GLP-1 analogue, liraglutide on endothelial function and glycemic metabolism compared with insulin glargine therapy.

Materials and Methods

In this multicenter, prospective randomized parallel-group comparison study, 31 diabetic outpatients (aged 60.3 ± 10.3 years with HbA1c levels of 8.6 ± 0.8%) with current metformin and/or sulfonylurea treatment were enrolled and randomly assigned to receive liraglutide or glargine therapy once daily for 14 weeks. Flow mediated dilation (FMD), a comprehensive panel of hemodynamic parameters (Task Force Monitor), and serum metabolic markers were assessed before and after the treatment period.

Results

A greater reduction (worsening) in %FMD was observed in the glargine group, although this change was not statistically different from the liraglutide group (liraglutide; 5.7 to 5.4%, glargine 6.7 to 5.7%). The augmentation index, C-peptide index, derivatives of reactive oxygen metabolites and BMI were significantly improved in the liraglutide group. Central systolic blood pressure and NT-proBNP also tended to be improved in the liraglutide-treated group, while improvements in HbA1c levels were similar between groups. Cardiac index, blood pressure and most other metabolic parameters were not different.

Conclusions

Regardless of glycemic improvement, early liraglutide therapy did not affect endothelial function but may provide favorable effects on beta-cell function and cardioprotection in type 2 diabetics without advanced atherosclerosis.

Trial Registration

UMIN Clinical Trials Registry System as trial ID UMIN000005331.

Feasibility of very-high resolution ultrasound to assess elastic and muscular arterial wall morphology in adolescents attending an outpatient clinic for obesity and lipid abnormalities

OBJECTIVE

Atherosclerosis begins during early life and is accelerated in individuals with cardiovascular risk factors. We hypothesized that very-high resolution ultrasound (VHRU, 25-55 MHz) could feasibly detect early arterial changes in adolescents with risk factors.

METHODS

We prospectively imaged the carotid, brachial and radial arterial morphology (far wall intima-media thickness, IMT; adventitia thickness, AT) by VHRU in 58 youths (age 14 ± 2 years) attending a Pediatric Preventive Cardiology Clinic for assessment and management of cardiovascular risk factors and compared the findings to those from an age-matched group of 67 controls.

RESULTS

Brachial and radial imaging was successful for all subjects. The carotid far wall could not be imaged in 7% of the patients due to limitations in penetration. VHRU image quality was related to body size and imaging depth. Imaging and analysis time were 12 ± 3 and 18 ± 3 min, respectively. Carotid IMT was increased in patients (0.42 ± 0.05 vs. 0.40 ± 0.06 mm, p = 0.05). No differences were found in brachial or radial IMT or AT vs. controls. Age, male gender, body mass index, systolic blood pressure (BP), but not lipid levels, were associated with arterial IMT in regression analyses.

CONCLUSION

VHRU is feasible in imaging carotid and peripheral muscular artery IMT in adolescents. The arterial IMT is associated with age, gender, adiposity and systolic BP, but not lipid levels, in this adolescent population. Further studies including patients with manifest clinical atherosclerosis are needed to assess if VHRU has applications in atherosclerosis research.

Extracellular matrix alterations in hypertensive vascular remodeling

Vascular cells are very sensitive to their hemodynamic environment. Any change in blood pressure or blood flow can be sensed by endothelial and vascular smooth muscle cells and ultimately results in structural modifications within the vascular wall that accommodate the new conditions. In the case of hypertension, the increase in arterial stretch stimulates vessel thickening to normalize the tensile forces. This process requires modification of the extracellular matrix and of cell-matrix interactions, which mainly involves extracellular proteases. In hypertension, chronic exposure of the arterial wall to stretch leads to vascular remodeling, arterial stiffness and calcification, which finally affect target organ function. This review surveys how mechanical stretch regulates extracellular proteases, considering the signaling pathways involved and the consequences on the cardiovascular system.

Elevated Plasma Plasminogen Activator Inhibitor Type-1 is an Independent Predictor of Coronary Microvascular Dysfunction in Hypertension

BACKGROUND

Elevated plasma plasminogen activator inhibitor-1 (PAI-1) is related to cardiovascular events, but its role in subclinical coronary microvascular dysfunction remains unknown. Thus, in the present study it was investigated whether elevated plasma PAI-1 activity is associated with coronary microvascular dysfunction in hypertensive patients.

METHODS AND RESULTS

Thirty patients with untreated essential hypertension and 10 age-matched healthy controls were studied prospectively. Myocardial blood flow (MBF) was measured by using (15)O-water positron emission tomography. Clinical variables associated with atherosclerosis (low-density lipoprotein-cholesterol, high-density lipoprotein (HDL)-cholesterol, triglyceride, homeostasis model assessment (HOMA-IR), and PAI-1 activity) were assessed to determine their involvement in coronary microvascular dysfunction. Adenosine triphosphate (ATP)-induced hyperemic MBF and coronary flow reserve (CFR) were significantly lower in hypertensive patients than in healthy controls (ATP-induced MBF: 2.77+/-0.82 vs 3.49+/-0.71 ml x g(-1) x min(-1); p<0.02 and CFR: 2.95 +/-1.06 vs 4.25+/-0.69; p<0.001). By univariate analysis, CFR was positively correlated with HDL-cholesterol (r=0.46, p<0.02), and inversely with HOMA-IR (r=-0.39, p<0.05) and PAI-1 activity (r=-0.61, p<0.001). By multivariate analysis, elevated PAI-1 activity remained a significant independent determinant of diminished CFR.

CONCLUSIONS

Elevated plasma PAI-1 activity was independently associated with coronary microvascular dysfunction, which suggests that plasma PAI-1 activity is an important clue linking hypofibrinolysis to the development of atherosclerosis.

Cross-Sectional Relations of Multiple Biomarkers From Distinct Biological Pathways to Brachial Artery Endothelial Function

Background— Endothelial dysfunction is a critical intermediate phenotype in the pathogenesis of cardiovascular disease. We evaluated the relative contributions of distinct biological pathways to interindividual variation in endothelial function by relating prototype biomarkers (representing these pathways) to brachial artery vasodilator function.

Methods and Results— We investigated the cross-sectional relations of a panel of 7 biomarkers measured at a routine examination to brachial artery vasodilator function (flow-mediated dilation [FMD] and reactive hyperemia) assessed at a subsequent examination (mean interval, 2.9 years) in 2113 Framingham Heart Study participants (mean age, 61 years; 54% women). We selected biomarkers from 4 biological domains: neurohormonal (N-terminal pro-atrial natriuretic peptide [N-ANP], B-type natriuretic peptide [BNP], renin, aldosterone), hemostatic factors (plasminogen activator inhibitor-1 [PAI-1]), inflammation (C-reactive protein [CRP]), and target organ damage (urine albumin-creatinine ratio). In age- and sex-adjusted models, several biomarkers were related to baseline brachial artery diameter (PAI-1, CRP, urine albumin-creatinine ratio), baseline mean flow (N-ANP, BNP, PAI-1, CRP, aldosterone), FMD (N-ANP, PAI-1, CRP, renin), and reactive hyperemia (BNP, PAI-1, CRP, renin, urine albumin-creatinine ratio). In multivariable analyses relating the 7 biomarkers conjointly to each vascular function measure (adjusting for known risk factors), N-ANP and renin were positively related to FMD ( P =0.001 and P =0.04, respectively), and N-ANP was inversely related to baseline mean flow velocity ( P =0.01). None of the other biomarkers was significantly related to the vascular function measures studied.

Conclusions— In our large community-based sample, a conservative strategy relating several biomarkers to vascular endothelial function identified plasma N-ANP as a key correlate of mean flow under basal conditions and of FMD in response to forearm cuff occlusion.

Increased plasma concentrations of N-terminal pro-brain natriuretic peptide reflect the presence of mildly reduced left ventricular diastolic function in hypertension

BACKGROUND

The potential use of assays of N-terminal pro-brain natriuretic peptide for detection of diastolic abnormalities associated with alterations in blood pressure has not been elucidated. This study was designed to determine whether increased plasma concentrations of N-terminal pro-brain natriuretic peptide sensitively reflect abnormal diastolic function associated with hypertension.

METHODS

Concentrations of N-terminal pro-brain natriuretic peptide in plasma were assayed in 40 previously untreated hypertensive patients without overt congestive heart failure and in 20 age and sex-matched controls. Hypertensive patients were studied with the use of pulsed Doppler and color M-mode Doppler echocardiography for the evaluation of left ventricular diastolic function.

RESULTS

Concentrations of N-terminal pro-brain natriuretic peptide were elevated in hypertensive patients [75.1+/-75.2 (SD) pg/ml compared with 37.9+/-38.5 in controls, P<0.05]. In hypertensive patients, concentrations of N-terminal pro-brain natriuretic peptide were negatively correlated with the ratio of color M-mode flow propagation velocity to transmitral E velocity consistent with the view that increased concentrations of N-terminal pro-brain natriuretic peptide are indicative of alterations in diastolic function. Hypertensive patients with N-terminal pro-brain natriuretic peptide values above the mean value in the control group exhibited significantly increased brachial intimal-medial thickness and reduced wall stress, consistent with the view that increased N-terminal pro-brain natriuretic peptide was associated with favorable peripheral arterial remodeling.

CONCLUSIONS

Elevated concentrations of N-terminal pro-brain natriuretic peptide in plasma reflect the presence of left ventricular diastolic abnormalities and peripheral arterial remodeling in asymptomatic patients with hypertension.