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

Twenty years of progress in angiotensin converting enzyme 2 and its link to SARS-CoV-2 disease

The virulence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the aggressive nature of the disease has transformed the universal pace of research in the desperate attempt to seek effective therapies to halt the morbidity and mortality of this pandemic. The rapid sequencing of the SARS-CoV-2 virus facilitated identification of the receptor for angiotensin converting enzyme 2 (ACE2) as the high affinity binding site that allows virus endocytosis. Parallel evidence that coronavirus disease 2019 (COVID-19) disease evolution shows greater lethality in patients with antecedent cardiovascular disease, diabetes, or even obesity questioned the potential unfavorable contribution of angiotensin converting enzyme (ACE) inhibitors or angiotensin II (Ang II) receptor blockers as facilitators of adverse outcomes due to the ability of these therapies to augment the transcription of Ace2 with consequent increase in protein formation and enzymatic activity. We review, here, the specific studies that support a role of these agents in altering the expression and activity of ACE2 and underscore that the robustness of the experimental data is associated with weak clinical long-term studies of the existence of a similar regulation of tissue or plasma ACE2 in human subjects.

Key Strategies for Clinical Management and Improvement of Healthcare Services for Cardiovascular Disease and Diabetes Patients in the Coronavirus (COVID-19) Settings: Recommendations From the REPROGRAM Consortium

Patients with cardiovascular disease and diabetes are at potentially higher risk of infection and fatality due to COVID-19. Given the social and economic costs associated with disability due to these conditions, it is imperative that specific considerations for clinical management of these patients be observed. Moreover, the reorganization of health services around the pandemic response further exacerbates the growing crisis around limited access, treatment compliance, acute medical needs, and mental health of patients in this specific subgroup. Existing recommendations and guidelines emanating from respective bodies have addressed some of the pressure points; however, there are variations and limitations vis a vis patient with multiple comorbidities such as obesity. This article will pull together a comprehensive assessment of the association of cardiovascular disease, diabetes, obesity and COVID-19, its impact on the health systems and how best health systems can respond to mitigate current challenges and future needs. We anticipate that in the context of this pandemic, the cardiovascular disease and diabetes patients need a targeted strategy to ensure the harm to this group does not translate to huge costs to society and to the economy. Finally, we propose a triage and management protocol for patients with cardiovascular disease and diabetes in the COVID-19 settings to minimize harm to patients, health systems and healthcare workers alike.

COVID-19 and Cardiovascular Disease

Coronavirus disease 2019 (COVID-19) is a global pandemic affecting 185 countries and >3 000 000 patients worldwide as of April 28, 2020. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2, which invades cells through the angiotensin-converting enzyme 2 receptor. Among patients with COVID-19, there is a high prevalence of cardiovascular disease, and >7% of patients experience myocardial injury from the infection (22% of critically ill patients). Although angiotensin-converting enzyme 2 serves as the portal for infection, the role of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers requires further investigation. COVID-19 poses a challenge for heart transplantation, affecting donor selection, immunosuppression, and posttransplant management. There are a number of promising therapies under active investigation to treat and prevent COVID-19.

A novel rodent model of pregnancy complications associated with genetically determined angiotensin-converting enzyme (ACE) activity

Brown Norway (BN) and Lewis (LW) inbred rat strains harbor different angiotensin-converting enzyme ( Ace) polymorphisms that result in higher ACE activity in BN than LW rats. Thus we hypothesized that pregnant BN rats would show pregnancy complications linked to angiotensin II (AII) activity. We performed longitudinal and cross-sectional studies in pregnant LW and BN rats. We found that BN rats have significantly higher ACE activity and AII levels at prepregnancy and throughout pregnancy compared with LW rats, except at midgestation. BN placentas and maternal kidneys had significantly higher expression of AII receptor 1 (AGTR1) and lower expression of AGTR2 than the respective LW placentas and maternal kidneys. Renin-angiotensin system activation in BN rats correlated with hypertension and proteinuria at gestational days 17-21, which were resolved after delivery. In addition, BN rat pregnancies were characterized by significant fetal loss, restricted growth in surviving fetuses, decreased uteroplacental blood flows, and decreased trophoblast remodeling of uterine arteries compared with LW pregnancies. Short-term losartan treatment significantly increased uteroplacental blood flow and fetal weight and decreased maternal blood pressure (BP) and proteinuria in BN pregnancies. In contrast, losartan treatment significantly decreased uteroplacental blood flow and fetal weight but had no significant effect on maternal BP in LW pregnancies. We conclude that Ace polymorphisms play an important role in the reproductive phenotype of BN and LW rats and that BN rats are a novel model of pregnancy complications in association with genetically controlled, increased ACE activity.

Determination of Angiotensin-(1-7) with HPLC/Fluorescence-Detection

Angiotensin-(1-7) is an important active component in the renin-angiotensin-system. Due to its cardio protective effects it is now under investigation in combination with antioxidants as a reperfusion solution. The combination showed impressive effects on isolated hearts of male Wistar rats after induced ischemia. In this work a high performance liquid chromatography method with fluorescence detection was developed for the first time for in-process measurements as well as for stability tests of the peptide in the novel antioxidant-containing Karal® solution. For fluorescence detection of angiotensin-(1-7) fluorescamine as derivatization dye was applied. Under optimized conditions the method showed linearity over the range of 50 to 5000 ng/mL with R(2) of 0.9988 and an overall precision better than 5.0 %. LOD and LOQ were determined to be in the femtomol range on column. It was found that stability of angiotensin-(1-7) could be significantly improved in the antioxidant containing preparation compared to aqueous solutions.

Impact of genetic background and aging on mesenteric collateral growth capacity in Fischer 344, Brown Norway, and Fischer 344 x Brown Norway hybrid rats

Available studies indicate that both genetic background and aging influence collateral growth capacity, but it is not known how their combination affects collateral growth. We evaluated collateral growth induced by ileal artery ligation in Fischer 344 (F344), Brown Norway (BN), and the first generation hybrid of F344 x BN (F1) rats available for aging research from the National Institute on Aging. Collateral growth was determined by paired diameter measurements in anesthetized rats immediately and 7 days postligation. In 3-mo-old rats, significant collateral growth occurred only in BN (35% +/- 11%, P < 0.001). The endothelial cell number in arterial cross sections was also determined, since this precedes shear-mediated luminal expansion. When compared with the same animal controls, the intimal cell number was increased only in BN rats (92% +/- 21%, P < 0.001). The increase in intimal cell number and the degree of collateral luminal expansion in BN rats was not affected by age from 3 to 24 mo. Immunohistochemical studies demonstrated that intimal cell proliferation was much greater in the collaterals of BN than of F1 rats. The remarkable difference between these three strains of rats used in aging research and the lack of an age-related impairment in the BN rats are novel observations. These rat strains mimic clinical observations of interindividual variation in collateral growth capacity and the impact of age on arteriogenesis and should be useful models to investigate the molecular mechanisms responsible for such differences.

Rho kinase activation and gene expression related to vascular remodeling in normotensive rats with high angiotensin I converting enzyme levels

The RhoA/Rho kinase (ROCK) pathway is a new mechanism of remodeling and vasoconstriction. Few data are available regarding ROCK activation when angiotensin I-converting enzyme is high and blood pressure is normal. We hypothesized that ROCK is activated in the vascular wall in normotensive rats with genetically high angiotensin I-converting enzyme levels, and it causes increased vascular expression of genes promoting vascular remodeling and also oxidative stress. Aortic ROCK activation, mRNA and protein levels (of monocyte chemoattractant protein-1, transforming growth factor [TGF]-beta(1), and plasminogen activator inhibitor-1 [PAI-1]), NADPH oxidase activity, and O(2)(*-) production were measured in normotensive rats with genetically high (Brown Norway [BN]) and low (Lewis) angiotensin-I-converting enzyme levels and in BN rats treated with the ROCK antagonist fasudil (100 mg/kg per day) for 7 days. ROCK activation was 12-fold higher in BN versus Lewis rats (P<0.05) and was reduced with fasudil by 100% (P<0.05). Aortic TGF-beta1, PAI-1, and monocyte chemoattractant protein-1 mRNA levels were higher in BN versus Lewis rats by 300%, 180%, and 1000%, respectively (P<0.05). Aortic TGF-beta1, PAI-1, and monocyte chemoattractant protein-1 protein levels were higher in BN versus Lewis rats (P<0,05). Fasudil reduced TGF-beta1 and PAI-1 mRNA and TGF-beta1, PAI-1, and monocyte chemoattractant protein-1 protein aortic levels to those observed in Lewis rats. Aortic reduced nicotinamide-adenine dinucleotide phosphate oxidase activity and (*)O(2)(-) production were increased by 88% and 300%, respectively, in BN rats (P<0.05) and normalized by fasudil. In conclusion, ROCK is significantly activated in the aortic wall in normotensive rats with genetically high angiotensin-I-converting enzyme and angiotensin II, and it causes activation of genes that promote vascular remodeling and also increases vascular oxidative stress.