Direct renin inhibitors as antihypertensive agents

Mathematical modeling of antihypertensive therapy

Hypertension is a multifactorial disease arising from complex pathophysiological pathways. Individual characteristics of patients result in different responses to various classes of antihypertensive medications. Therefore, evaluating the efficacy of therapy based on in silico predictions is an important task. This study is a continuation of research on the modular agent-based model of the cardiovascular and renal systems (presented in the previously published article). In the current work, we included in the model equations simulating the response to antihypertensive therapies with different mechanisms of action. For this, we used the pharmacodynamic effects of the angiotensin II receptor blocker losartan, the calcium channel blocker amlodipine, the angiotensin-converting enzyme inhibitor enalapril, the direct renin inhibitor aliskiren, the thiazide diuretic hydrochlorothiazide, and the β-blocker bisoprolol. We fitted therapy parameters based on known clinical trials for all considered medications, and then tested the model's ability to show reasonable dynamics (expected by clinical observations) after treatment with individual drugs and their dual combinations in a group of virtual patients with hypertension. The extended model paves the way for the next step in personalized medicine that is adapting the model parameters to a real patient and predicting his response to antihypertensive therapy. The model is implemented in the BioUML software and is available at https://gitlab.sirius-web.org/virtual-patient/antihypertensive-treatment-modeling.

Systemic and tissue-specific effects of aliskiren on the RAAS and carbohydrate/lipid metabolism in obese patients with hypertension

Aliskiren penetrates adipose and skeletal muscle in hypertensive patients with abdominal obesity and reduces renin-angiotensin-aldosterone system activity. After discontinuation, blood pressure-lowering effects are observed possibly through drug-tissue binding. We performed microdialysis evaluation of adipose tissue and skeletal muscle before and during an insulin-modified frequently sampled intravenous glucose tolerance test (IM-FSIGT). Aliskiren 300 mg (n = 8) or amlodipine 5 mg (n = 8) once daily were administered during a 12-week randomized treatment period. Aliskiren elicited variable changes in median interstitial angiotensin II (Ang II) in adipose (2.60-1.30 fmol/mL) and skeletal muscle (2.23-0.68 fmol/mL); amlodipine tended to increase adipose and skeletal muscle Ang II (P = .066 for skeletal muscle treatment difference). Glucose/insulin increased median plasma Ang II 1 hour after glucose injection (1.04-2.50 fmol/mL; P = .001), which was markedly attenuated by aliskiren but not amlodipine. Aliskiren increased glucose disposition index (P = .012) and tended to increase acute insulin response to glucose (P = .067). Fasting adipose glycerol (-17%; P = .064) and fasting muscle glucose dialysate (-17%; P = .025) were decreased by aliskiren but not amlodipine. In summary, aliskiren decreased Ang II production in response to glucose/insulin stimulus and elicited metabolic effects in adipose and skeletal muscle suggestive of increased whole-body glucose utilization.

Combination Treatment With Antihypertensive Agents Enhances the Effect of Qiliqiangxin on Chronic Pressure Overload-induced Cardiac Hypertrophy and Remodeling in Male Mice

Supplemental Digital Content is Available in the Text.

We previously showed that Qiliqiangxin (QL) capsules could ameliorate cardiac hypertrophy and remodeling in a mouse model of pressure overload. Here, we compared the effects of QL alone with those of QL combined with the following 3 types of antihypertensive drugs on cardiac remodeling and dysfunction induced by pressure overload for 4 weeks in mice: an angiotensin II type 1 receptor (AT₁-R) blocker (ARB), an angiotensin-converting enzyme inhibitor (ACEI), and a β-adrenergic receptor (β-AR) blocker (BB). Adult male mice (C57B/L6) were subjected to either transverse aortic constriction or sham operation for 4 weeks, and the drugs (or saline) were orally administered through gastric tubes. Cardiac function and remodeling were evaluated through echocardiography, catheterization, histology, and analysis of hypertrophic gene expression. Cardiomyocyte apoptosis and autophagy, AT₁-R and β₁-AR expression, and cell proliferation–related molecules were also examined. Although pressure overload–induced cardiac remodeling and dysfunction, hypertrophic gene reprogramming, AT₁-R and β₁-AR expression, and ERK phosphorylation were significantly attenuated by QL alone, QL + ARB, QL + ACEI, and QL + BB, the attenuation was stronger in the combination treatment groups. Moreover, apoptosis was reduced to a larger extent by each combination treatment than by QL alone, whereas autophagy was more strongly attenuated by either QL + ARB or QL + ACEI. None of the treatments significantly upregulated ErbB2 or ErbB4 phosphorylation, and none significantly downregulated C/EBPβ expression. Therefore, the effects of QL on chronic pressure overload–induced cardiac remodeling may be significantly increased when QL is combined with an ARB, an ACEI, or a BB.

Angiotensin II and oxidative stress in the failing heart

SIGNIFICANCE

Despite recent medical advances, cardiovascular disease and heart failure (HF) continue to be major health concerns, and related mortality remains high. As a result, investigation of the mechanisms involved in the development of HF continues to be an active field of study.

RECENT ADVANCES

The renin-angiotensin system (RAS) and its effector molecule, angiotensin (Ang) II, affect cardiac function through both systemic and local actions, and have been shown to play a major role in cardiac remodeling and dysfunction in the failing heart. Many of the downstream effects of AngII signaling are mediated by elevated levels of reactive oxygen species (ROS) and oxidative stress, which have also been implicated in the pathology of HF.

CRITICAL ISSUES

Inhibitors of the RAS have proven beneficial in the treatment of patients at risk for and suffering from HF, but remain only partially effective. ROS can be generated from several different sources, and the oxidative state is normally tightly regulated in the heart. How AngII increases ROS levels and causes dysregulation of the cardiac oxidative state has been the subject of considerable interest in recent years.

FUTURE DIRECTIONS

A better understanding of this process and the mechanisms involved should lead to the development of more effective HF therapies and improved outcomes.

Comparative efficacy and safety of combination aliskiren/amlodipine and amlodipine monotherapy in African Americans with stage 2 hypertension and obesity or metabolic syndrome

The renin-angiotensin system (RAS) is a common link between hypertension and comorbidities of obesity and metabolic syndrome (MetS). We evaluated the antihypertensive efficacy and safety of the combination direct renin inhibitor, aliskiren, with amlodipine versus amlodipine alone in self-identified African Americans with stage 2 hypertension in a subgroup of patients with obesity or MetS participating in the Aliskiren Amlodipine Combination in African AmEricans with Stage 2 HypertenSion (AACESS) trial. Subjects, newly diagnosed and treatment naive or taking three or fewer antihypertensive drugs with a mean sitting systolic blood pressure (msSBP) of 160-199 mm Hg were randomized to receive aliskiren/amlodipine 150/5 mg or amlodipine 5 mg for 1 week; force-titrated to aliskiren/amlodipine 300/10 mg or amlodipine 10 mg, for an additional 7 weeks. Overall, 292 obese (body mass index ≥30 kg/m(2)) and 197 MetS subjects had baseline msSBP ranging from 167.0 to 167.5 mm Hg. Least-square mean reductions from baseline to 8 weeks in msSBP, the primary efficacy variable, were significantly higher with aliskiren/amlodipine than with amlodipine in both obese (-33.7 mm Hg vs. -27.9 mm Hg; P < .001) and MetS subjects (-36.4 mm Hg vs. -28.5 mm Hg; P < .001). Both treatments were well tolerated. Aliskiren/amlodipine 300/10 mg is more effective than amlodipine 10 mg in African Americans with stage 2 hypertension and obesity or MetS.

Knocking out angiotensin II in the heart

Despite ongoing medical advances, cardiovascular disease continues to be a leading health concern. The renin-angiotensin system (RAS) plays an important role in regulating cardiovascular function, and is, therefore, the subject of extensive study. Several drugs currently used to treat hypertension and heart failure are designed to target angiotensin II synthesis and function, but thus far, none have been able to completely block the effects of RAS signaling. This review discusses current and emerging approaches towards inhibiting cardiac RAS function in order to further improve cardiovascular disease outcomes.