Neuronal uptake of nanoformulated superoxide dismutase and attenuation of angiotensin II-dependent hypertension after central administration

Excessive production of superoxide (O₂⁻) in the central nervous system has been widely implicated in the pathogenesis of cardiovascular diseases, including chronic heart failure and hypertension. In an attempt to overcome the failed therapeutic impact of currently available antioxidants in cardiovascular disease, we developed a nanomedicine-based delivery system for the O₂⁻-scavenging enzyme copper/zinc superoxide dismutase (CuZnSOD), in which CuZnSOD protein is electrostatically bound to a poly-l-lysine (PLL₅₀)–polyethylene glycol (PEG) block copolymer to form a CuZnSOD nanozyme. Various formulations of CuZnSOD nanozyme are covalently stabilized by either reducible or nonreducible crosslinked bonds between the PLL₅₀–PEG polymers. Herein, we tested the hypothesis that PLL₅₀–PEG CuZnSOD nanozyme delivers active CuZnSOD protein to neurons and decreases blood pressure in a mouse model of angiotensin II (AngII)-dependent hypertension. As determined by electron paramagnetic resonance spectroscopy, nanozymes retain full SOD enzymatic activity compared to native CuZnSOD protein. Nonreducible CuZnSOD nanozyme delivers active CuZnSOD protein to central neurons in culture (CATH.a neurons) without inducing significant neuronal toxicity. Furthermore, in vivo studies conducted in adult male C57BL/6 mice demonstrate that hypertension established by chronic subcutaneous infusion of AngII is significantly attenuated for up to 7 days after a single intracerebroventricular injection of nonreducible nanozyme. These data indicate the efficacy of nonreducible PLL₅₀–PEG CuZnSOD nanozyme in counteracting excessive O₂⁻ and decreasing blood pressure in AngII-dependent hypertensive mice after central administration. Additionally, this study supports the further development of PLL₅₀–PEG CuZnSOD nanozyme as an antioxidant-based therapeutic option for hypertension.     

Characterization of proximal pulmonary arterial cells from chronic thromboembolic pulmonary hypertension patients

Background

Chronic thromboembolic pulmonary hypertension (CTEPH) is associated with proximal pulmonary artery obstruction and vascular remodeling. We hypothesized that pulmonary arterial smooth muscle (PASMC) and endothelial cells (PAEC) may actively contribute to remodeling of the proximal pulmonary vascular wall in CTEPH. Our present objective was to characterize PASMC and PAEC from large arteries of CTEPH patients and investigate their potential involvement in vascular remodeling.

Methods

Primary cultures of proximal PAEC and PASMC from patients with CTEPH, with non-thromboembolic pulmonary hypertension (PH) and lung donors have been established. PAEC and PASMC have been characterized by immunofluorescence using specific markers. Expression of smooth muscle specific markers within the pulmonary vascular wall has been studied by immunofluorescence and Western blotting. Mitogenic activity and migratory capacity of PASMC and PAEC have been investigated in vitro.

Results

PAEC express CD31 on their surface, von Willebrand factor in Weibel-Palade bodies and take up acetylated LDL. PASMC express various differentiation markers including α-smooth muscle actin (α-SMA), desmin and smooth muscle myosin heavy chain (SMMHC). In vascular tissue from CTEPH and non-thromboembolic PH patients, expression of α-SMA and desmin is down-regulated compared to lung donors; desmin expression is also down-regulated in vascular tissue from CTEPH compared to non-thromboembolic PH patients. A low proportion of α-SMA positive cells express desmin and SMMHC in the neointima of proximal pulmonary arteries from CTEPH patients. Serum-induced mitogenic activity of PAEC and PASMC, as well as migratory capacity of PASMC, were increased in CTEPH only.

Conclusions

Modified proliferative and/or migratory responses of PASMC and PAEC in vitro, associated to a proliferative phenotype of PASMC suggest that PASMC and PAEC could contribute to proximal vascular remodeling in CTEPH.     

肾素- 血管紧张素- 醛固酮系统与原发性高血压病的关系

目的:探讨血浆肾素-血管紧张素系统与原发性高血压病的关系。方法:采用病例-对照研究设计,入选125例原发性高血压病患者与60例血压正常健康体检者为对照组。采用放射免疫方法测定立位、卧位血浆肾素活性(PRA),醛固酮(ALD)浓度及血管紧张素Ⅱ(AngⅡ)浓度。结果:原发性高血压患者,立位、卧位血浆PRA均低于正常对照组(P<0.05),而ALD浓度及AngⅡ浓度均高于正常对照组(P<0.05)。根据高血压病1级、2级、3级分组,立位、卧位血浆PRA均依次降低(P<0.05);而ALD浓度及AngⅡ浓度依次升高(P<0.05)。结论:肾素-血管紧张素-醛固酮系统与原发性高血压病的发病关系密切,血浆PRA水平、AngⅡ及ALD浓度有望成为原发性高血压病分级的有效指标;降低原发性高血压患者AngⅡ及ALD量是治疗高血压病的关键,血浆AngII、ALD也有望成为评价原发性高血压病疗效的指标。     

阻塞性睡眠呼吸暂停综合征与高血压临床关系分析

目的:研究阻塞性睡眠呼吸暂停综合征与高血压的临床关系及相关机制。方法:将258例鼾症患者分为三组:单纯鼾症对照组(N组)、单纯OSAHS组(O组)、OSAHS合并高血压组(O+H组)。对三组患者进行临床基础资料收集,ESS问卷调查及EP评分,多导睡眠监测及血压测定。结果:三组鼾症患者之间年龄、性别、吸烟、饮酒差异无统计学意义(P>0.05),OSAHS组及OSAHS+HT组体重指数及颈围明显高于单纯鼾症组,差异有统计学意义(P<0.05);与单纯鼾症组比较,OSAHS组及OSAHS+HT组的EP评分、AHI、LaSO2(%)、MSaO2、Ts90%差异明显有统计学意义(P<0.05);与对照组相比OSAHS组及OSAHS+HT组睡眠前后收缩压和舒张压升高,差异有统计学意义(P<0.05)。结论:阻塞性睡眠呼吸暂停综合征与高血压关系密切,慢性间歇缺氧是引起高血压的核心机制。     

原发性高血压患者血浆ET-1含量与血小板参数相关性研究

目的:探讨血浆内皮素-1 (Endothelin-1,ET-1)含量变化和血小板功能异常在原发性高血压疾病进程中相关性及意义.方法:选择98例原发性高血压患者作为实验组和30例健康受试者作为正常对照组.实验组又根据高血压分级标准分为轻度高血压组(L组),中度高血压组(M组)和重度高血压组(S组),分别检测各组患者血浆ET-1含量和血小板各项参数值.结果:实验组血浆ET-1含量、平均血小板体积(mean platelet volume,MPV)、血小板分布宽度(platelet distribution width,PDW)明显高于对照组(P＜0.05),血小板计数(platelet count,PLT)和血小板压积(platelet hematocrit,PCT)明显低于对照组(P＜0.05);L组、M组和S组ET-1含量、MPV和PDW值呈进行性升高(P＜0.05),PLT和PCT值呈进行性降低(P＜0.05).结论:血浆ET-1含量和血小板各项参数变化与疾病的进展和危重程度存在相关性,对原发性高血压的诊断治疗及预后评估有重要意义.     

Maternally inherited hypertension is associated with the mitochondrial tRNA(Ile) A4295G mutation in a Chinese family

Mutations in mitochondrial DNA have been associated with cardiovascular disease. We report here the clinical, genetic, and molecular characterization of one three-generation Han Chinese family with maternally transmitted hypertension. All matrilineal relatives in this family exhibited the variable degree of hypertension at the age at onset of 36 to 56 years old. Sequence analysis of the complete mitochondrial DNA in this pedigree revealed the presence of the known hypertension-associated tRNA^Ile A4295G mutation and 33 other variants, belonging to the Asian haplogroup D4j. The A4295G mutation, which is extraordinarily conserved from bacteria to human mitochondria, is located at immediately 3′ end to the anticodon, corresponding to conventional position 37 of tRNA^Ile. The occurrence of the A4295G mutation in several genetically unrelated pedigrees affected by cardiovascular disease but the absence of 242 Chinese controls strongly indicates that this mutation is involved in the pathogenesis of cardiovascular disease. Of other variants, the tRNA^Glu A14693G and ND1 G11696A mutations were implicated to be associated with other mitochondrial disorders. The A14693G mutation, which is a highly conserved nucleoside at the TψC-loop of tRNA^Glu, has been implicated to be important for tRNA structure and function. Furthermore, the ND4 G11696A mutation was associated with Leber’s hereditary optic neuropathy. Therefore, the combination of the A4295G mutation in the tRNA^Ile gene with the ND4 G11696A mutation and tRNA^Glu A14693G mutation may contribute to the high penetrance of hypertension in this Chinese family.     

Endothelial progenitor cells in cardiovascular diseases

Endothelial dysfunction has been associated with the development of atherosclerosis and cardiovascular diseases. Adult endothelial progenitor cells(EPCs) are derived from hematopoietic stem cells and are capable of forming new blood vessels through a process of vas-culogenesis. There are studies which report correlations between circulating EPCs and cardiovascular risk fac-tors. There are also studies on how pharmacotherapies may influence levels of circulating EPCs. In this review, we discuss the potential role of endothelial progenitor cells as both diagnostic and prognostic biomarkers. In addition, we look at the interaction between cardio-vascular pharmacotherapies and endothelial progenitor cells. We also discuss how EPCs can be used directly and indirectly as a therapeutic agent. Finally, we evalu-ate the challenges facing EPC research and how these may be overcome.     

Effect of hypertension on angiotensin-(1-7) levels in rats with different angiotensin-I converting enzyme polymorphism

To determine circulating angiotensin-(1-7) [Ang-(1,7)] levels in rats with different angiotensin converting enzyme (ACE) genotypes and to evaluate the effect of hypertension on levels of this heptapeptide, plasma levels of angiotensin II (Ang II) and Ang-(1-7) were determined by HPLC and radioimmunoassay in (a) normotensive F0 and F2 homozygous Brown Norway (BN; with high ACE) or Lewis (with low ACE) rats and (b) in hypertensive F2 homozygous male rats (Goldblatt model). Genotypes were characterized by PCR and plasma ACE activity measured by fluorimetry. Plasma ACE activity was 2-fold higher (p < 0.05) in homozygous BN compared to homozygous Lewis groups. In the Goldblatt groups, a similar degree of hypertension and left ventricular hypertrophy was observed in rats with both genotypes. Plasma Ang II levels were between 300-400% higher (p < 0.05) in the BN than in the Lewis rats, without increment in the hypertensive animals. Plasma Ang-(1-7) levels were 75-87% lower in the BN rats (p < 0.05) and they were significantly higher (p < 0.05) in the hypertensive rats from both genotypes. Plasma levels of Ang II and Ang-(1-7) levels were inversely correlated in the normotensive rats (r = -0.64; p < 0.001), but not in the hypertensive animals. We conclude that there is an inverse relationship between circulating levels of Ang II and Ang-(1-7) in rats determined by the ACE gene polymorphism. This inverse relation is due to genetically determined higher ACE activity. Besides, plasma levels of Ang-(1-7) increase in renovascular hypertension.     

Aldosterone and the kidney: rapid regulation of renal microcirculation

Recent studies provide evidence that aldosterone (Aldo) accelerates hypertension, proteinuria and glomerulosclerosis in animal models of chronic renal failure. Although the underlying mechanisms are not well defined, Aldo may exert these deleterious renal effects by elevating renal vascular resistance (RVR) and glomerular capillary pressure (P(GC)). To test this possibility, we studied the action of Aldo on rabbit afferent (Af-) and efferent arterioles (Ef-Arts), crucial vascular segments to the control of glomerular hemodynamics. Aldo caused rapid (within 5 min) constriction in both arterioles. The constriction was not affected by spironolactone but was reproduced by membrane-impermeable albumin-conjugated Aldo, suggesting that vasoconstrictor actions are non-genomic. This notion was further supported by the finding that neither actinomycin D nor cycloheximide had effect. The vasoconstrictor action of Aldo on Af-Arts was inhibited by nifedipine (L-type calcium channel blocker), whereas that on Ef-Arts was inhibited by efonidipine (both L- and T-type calcium channel blocker) but not nifedipine. Disrupting the endothelium or nitric oxide (NO) synthesis inhibition augmented the vasoconstriction in Af-Arts, demonstrating that endothelium-derived NO modulates the vasoconstrictor actions of Aldo. Thus, Aldo causes non-genomic vasoconstriction via calcium mobilization thorough L- or T-type calcium channels in Af- or Ef-Arts, respectively. These vasoconstrictor actions on the glomerular microcirculation may play an important role in the pathophysiology and progression of renal diseases by elevating RVR and P(GC), especially when endothelium functions are impaired. In addition to our study, this review describes recent findings on the rapid cardiovascular actions of Aldo, with a particular attention to the renal hemodynamics.