aliskiren and Atherosclerosis

Renin-angiotensin-system (RAS) is an enzymatic cascade that plays a pivotal role in the development of arterial hypertension, kidney disease and cardiovascular disease. Inhibition of the RAS with angiotensin converting enzyme (ACE) inhibitors (ACE-Is) or angiotensin receptor blockers (ARBs) has proved to be a successful strategy for the treatment of hypertension and related cardiovascular disorders. However, by reducing feedback inhibition of renin release, the effects of ACE-Is and ARBs lead to an increase in plasma renin concentration (PRC) and activity (PRA), limiting a complete inhibition of the RAS. Consequently the effects of a different pharmacological strategy that completely blocks the RAS upstream has been assessed in the last years. In this context, aliskiren is the first representative of a new class of non-peptide orally active renin inhibitor that blocks the RAS at its rate-limiting step and induces a net reduction in PRA, angiotensin II and aldosterone levels. Aliskiren effectively reduces blood pressure as a monotherapy as well in combination therapy. In addition, aliskiren has a placebo-like tolerability profile at the licensed doses of 150 mg and 300 mg. Aliskiren also exhibits additive effects on blood pressure reduction when combined with drugs that lead to a reactive increase in the PRA, such as diuretics, ACE-Is or ARBs. In previous studies, aliskiren showed beneficial effects in patients with arterial hypertension and associated clinical conditions. However, later trials indicated that the use of aliskiren should be avoided in patients with renal failure or receiving ACE-Is or ARBs. The main aim of this review is to summarize the available data on its efficacy and safety profile, highlighting clinical implications from recent trials.

Topics: Amides; Animals; Antihypertensive Agents; Atherosclerosis; Blood Pressure; Drug Therapy, Combination; Fumarates; Humans; Hypertension; Hypertrophy, Left Ventricular; Renin

The renin-angiotensin system is well recognized as a mediator of pathophysiological events in atherosclerosis. The benefits of renin inhibition in atherosclerosis, especially when used in combination with angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ACEIs/ARBs) are currently not known. We hypothesized that treatment with the renin inhibitor aliskiren in patients with established cardiovascular disease will prevent the progression of atherosclerosis as determined by high-resolution magnetic resonance imaging (MRI) measurements of arterial wall volume in the thoracic and abdominal aortas of high-risk patients with preexisting cardiovascular disease.. This was a single-center, randomized, double-blind, placebo-controlled trial in patients with established cardiovascular disease. After a 2-week single-blind placebo phase, patients were randomized to receive either placebo (n=37, mean ± SD age 64.5 ± 8.9 years, 3 women) or 150 mg of aliskiren (n=34, mean ± SD age 63.9 ± 11.5 years, 9 women). Treatment dose was escalated to 300 mg at 2 weeks and maintained during the remainder of the study. Patients underwent dark-blood, 3-dimensional MRI assessment of atherosclerotic plaque in the thoracic and abdominal segments at baseline and on study completion or termination (up to 36 weeks of drug or matching placebo). Aliskiren use resulted in significant progression of aortic wall volume (normalized total wall volume 5.31 ± 6.57 vs 0.15 ± 4.39 mm(3), P=0.03, and percentage wall volume 3.37 ± 2.96% vs 0.97 ± 2.02%, P=0.04) compared with placebo. In a subgroup analysis of subjects receiving ACEI/ARB therapy, atherosclerosis progression was observed only in the aliskiren group, not in the placebo group.. MRI quantification of atheroma plaque burden demonstrated that aliskiren use in patients with preexisting cardiovascular disease resulted in an unexpected increase in aortic atherosclerosis compared with placebo. Although preliminary, these results may have implications for the use of renin inhibition as a therapeutic strategy in patients with cardiovascular disease, especially in those receiving ACEI/ARB therapy.. URL: http://ClinicalTrials.gov Unique identifier: NCT01417104.

Topics: Amides; Atherosclerosis; Cardiovascular Diseases; Disease Progression; Double-Blind Method; Female; Fumarates; Humans; Imaging, Three-Dimensional; Magnetic Resonance Imaging; Male; Middle Aged; Plaque, Atherosclerotic; Prospective Studies; Renin; Single-Blind Method

To evaluate whether the direct renin inhibitor, aliskiren, has a more favorable effect compared to amlodipine on atherosclerotic biomarkers in patients with stable coronary artery disease and diabetes currently receiving standard secondary prevention therapy.. A total of 38 patients were randomly assigned initially to either aliskiren (150 mg daily) or amlodipine (5 mg daily) for 2 weeks after which the dose of either medication was increased to its maximum daily dose for 4 additional weeks. Baseline and 6-week blood samples were analyzed for changes from baseline and between treatment groups for vascular and intracellular cell adhesion molecule, C-reactive protein, nitric oxide, plasminogen activator inhibitor 1, 8-isoprostane, and thiobarbituric acid reactive substances.. Thirty-one patients completed the study. More of the dropouts occurred in patients receiving aliskiren. Systolic blood pressure decreased in both treatment arms with no differences between the groups being noted. Plasminogen activator inhibitor 1, nitric oxide, and C-reactive protein concentrations increased in both groups from baseline but changes from baseline or between groups were not significant. Vascular and intracellular cell adhesion molecule, thiobarbituric acid reactive substances, and isoprostane concentrations decreased in each treatment arm from baseline, but these changes were not significant and no differences were noted between the groups.. Treatment with either aliskiren or amlodipine did not significantly alter surrogate biomarkers of atherosclerosis in patients with both diabetes and established cardiovascular disease already receiving appropriate secondary cardiovascular prevention therapy. The study is limited in its size and duration to see an effect.

Topics: Aged; Amides; Amlodipine; Atherosclerosis; Biomarkers; Blood Pressure; Coronary Artery Disease; Diabetes Mellitus, Type 2; Female; Follow-Up Studies; Fumarates; Humans; Male; Middle Aged; Prospective Studies; Renin

This study determined whether angiotensinogen (AGT) has angiotensin II-independent effects using multiple genetic and pharmacological manipulations.. All study mice were in low-density lipoprotein receptor -/- background and fed a saturated fat-enriched diet. In mice with floxed alleles and a neomycin cassette in intron 2 of the AGT gene (hypoAGT mice), plasma AGT concentrations were >90% lower compared with their wild-type littermates. HypoAGT mice had lower systolic blood pressure, less atherosclerosis, and diminished body weight gain and liver steatosis. Low plasma AGT concentrations and all phenotypes were recapitulated in mice with hepatocyte-specific deficiency of AGT or pharmacological inhibition of AGT by antisense oligonucleotide administration. In contrast, inhibition of AGT cleavage by a renin inhibitor, aliskiren, failed to alter body weight gain and liver steatosis in low-density lipoprotein receptor -/- mice. In mice with established adiposity, administration of AGT antisense oligonucleotide versus aliskiren led to equivalent reductions of systolic blood pressure and atherosclerosis. AGT antisense oligonucleotide administration ceased body weight gain and further reduced body weight, whereas aliskiren did not affect body weight gain during continuous saturated fat-enriched diet feeding. Structural comparisons of AGT proteins in zebrafish, mouse, rat, and human revealed 4 highly conserved sequences within the des(angiotensin I)AGT domain. des(angiotensin I)AGT, through adeno-associated viral infection in hepatocyte-specific AGT-deficient mice, increased body weight gain and liver steatosis, but did not affect atherosclerosis.. AGT contributes to body weight gain and liver steatosis through functions of the des(angiotensin I)AGT domain, which are independent of angiotensin II production.

Topics: Amides; Amino Acid Sequence; Angiotensin II; Angiotensinogen; Animals; Atherosclerosis; Blood Pressure; Conserved Sequence; Dependovirus; Diet, High-Fat; Disease Models, Animal; Fatty Liver; Fumarates; Genetic Vectors; Genotype; Hepatocytes; Hypertension; Liver; Male; Mice, Inbred C57BL; Mice, Knockout; Models, Molecular; Oligonucleotides, Antisense; Phenotype; Protein Binding; Protein Interaction Domains and Motifs; Receptors, LDL; Renin; Signal Transduction; Time Factors; Transduction, Genetic; Weight Gain

This case represents an individual with accelerating hypertension and declining kidney function associated with atherosclerotic renal artery stenosis. Key features include loss of GFR (reaching stage V CKD) during intensified antihypertensive drug therapy including agents that block the renin-angiotensin system and failure to appreciate the extent to which moderate renal artery stenosis was affecting his better kidney. Interpretation of duplex ultrasound studies was complicated by a discrepancy between near-normal peak systolic velocities and markedly abnormal segmental arterial waveforms. It was essential to recognize that both kidneys were abnormal and focus on recovery of perfusion to the better of these kidneys. Successful revascularization of one kidney allowed major improvement in GFR and BP control.

Topics: Aged; Amides; Antihypertensive Agents; Atherosclerosis; Atrophy; Blood Pressure; Carbazoles; Carvedilol; Disease Progression; Drug Therapy, Combination; Fumarates; Glomerular Filtration Rate; Humans; Hypertension; Kidney; Kidney Failure, Chronic; Male; Propanolamines; Renal Artery Obstruction; Stents; Teaching Rounds

Aliskiren is a direct renin inhibitor developed to treat hypertension. Several clinical studies have suggested that aliskiren has beneficial effects on cardiovascular diseases beyond its antihypertensive effect. In the present study, we examined whether aliskiren limits the progression of AAA (abdominal aortic aneurysm), VH (ventricular hypertrophy) and atherosclerosis in an AngII (angiotensin II)-infused mouse model. ApoE-/- (apolipoprotein-E-deficient) mice were infused subcutaneously with AngII (1000 ng/kg of body weight per day; 4 weeks) to induce AAA and VH. At the completion of the AngII infusion, mice were randomly allocated to three groups to receive vehicle control, low-dose aliskiren (10 mg/kg of body weight per day) or high-dose aliskiren (50 mg/kg of body weight per day) for 4 weeks. Suprarenal aortic diameter assessed by ultrasound was significantly smaller in mice administered aliskiren at days 42 and 56. Aliskiren also significantly reduced the normalized heart weight, ventricular myocyte cell width and aortic arch atherosclerosis. Aliskiren lowered PRR (pro-renin receptor) expression and MAPK (mitogen-activated protein kinase) activity in the suprarenal aorta and heart. Aortic infiltration of T-lymphocytes and macrophages was reduced by aliskiren. In conclusion, aliskiren limits the progression of AAA, VH and atherosclerosis in an AngII-infused mouse model.

Topics: Amides; Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; Atherosclerosis; Blood Pressure; Disease Models, Animal; Fumarates; Hypertension; Hypertrophy; Mice; Mice, Inbred C57BL; Mice, Knockout

The interaction between the renin-angiotensin system and toll-like receptors (TLRs) in the pathogenesis of advanced atherosclerotic plaques is not well understood. We studied the effects of the renin inhibitor aliskiren on the progression of advanced atherosclerotic plaque in apolipoprotein E-deficient (ApoE(-/-)) mice with a special focus on plaque neovessel formation.. Four-wk-old ApoE(-/-) mice were fed a high-fat diet for 8 wks, and the mice were randomly assigned to one of three groups and administered a vehicle, hydralazine, or aliskiren for an additional 12 wks. Aliskiren reduced the atherosclerotic plaque area and plaque neovessel density. It increased the plaque collagen and elastin contents, and reduced plasma angiotensin II levels and plaque macrophage infiltration and cathepsin S (CatS) protein. Aliskiren also decreased the levels of AT1R, gp91phox, TLR2, monocyte chemotactic protein-1, and CatS mRNAs in the aortic roots. Hydralazine had no beneficial vascular effects, although its administration resulted in the same degree of blood pressure reduction as aliskiren. CatS deficiency mimicked the aliskiren-mediated vasculoprotective effect in the ApoE(-/-) mice, but aliskiren showed no further benefits in ApoE(-/-) CatS(-/-) mice. In vitro, TLR2 silencing reduced CatS expression induced by angiotensin II. Moreover, aliskiren or the inhibition of CatS impaired the endothelial cell angiogenic action in vitro or/and ex vivo.. Renin inhibition appears to inhibit advanced plaque neovessel formation in ApoE(-/-) mice and to decrease the vascular inflammatory action and extracellular matrix degradation, partly by reducing AT1R/TLR2-mediated CatS activation and activity, thus regressing advanced atherosclerosis.

Topics: Amides; Angiotensin II; Animals; Aorta; Apolipoproteins E; Atherosclerosis; Blood Pressure; Carrier Proteins; Cathepsins; Chemokine CCL2; Extracellular Matrix; Fumarates; Gene Silencing; Human Umbilical Vein Endothelial Cells; Humans; Hydralazine; Immunohistochemistry; Intracellular Signaling Peptides and Proteins; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Neovascularization, Pathologic; Nuclear Proteins; Plaque, Atherosclerotic; Receptor, Angiotensin, Type 1; Renin; Toll-Like Receptor 2; Treatment Outcome; Vascular Cell Adhesion Molecule-1

Topics: Amides; Atherosclerosis; Endothelium; Fumarates; Humans; Renin; Stem Cells

Inhibition of the renin angiotensin system (RAS) has been consistently demonstrated to reduce atherosclerosis. However, there has been no direct comparison among the three available pharmacological modes of inhibiting the RAS, which are inhibitors of renin, ACE and angiotensin II type 1 receptor. The purpose of this study was to determine the relative effects of these three modes of pharmacological RAS inhibition in reducing atherosclerosis by determining the dose-response relationships.. Male LDL receptor -/- mice were administered either vehicle or any of three doses of aliskiren, enalapril or losartan through s.c. infusion for 12 weeks. All mice were fed a saturated fat-enriched diet during drug infusions. Systolic and diastolic BPs were measured during the study using a non-invasive tail-cuff system. Plasma cholesterol and renin concentrations, atherosclerotic lesions, and renal angiotensin II concentrations were determined at the termination of the study.. Plasma renin concentrations were increased by all three drugs. None of the drugs changed plasma cholesterol concentrations. All drugs produced a dose-related decrease in BP. All three drugs also profoundly reduced atherosclerosis in a dose-dependent manner. The highest dose of each drug markedly attenuated lesion size, with no significant differences between the different drugs. The highest dose of each drug also similarly reduced renal angiotensin II concentrations.. Drugs that inhibit the RAS, irrespective of their mode of inhibition, profoundly affect atherosclerotic lesion development in a dose-dependent manner.

Topics: Amides; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Animals; Aorta; Atherosclerosis; Blood Pressure; Cholesterol; Diet, High-Fat; Enalapril; Fumarates; Hypercholesterolemia; Kidney; Losartan; Male; Mice; Mice, Knockout; Receptor, Angiotensin, Type 1; Receptors, LDL; Renin; Renin-Angiotensin System

Aliskiren is the first commercially available, orally active, direct renin inhibitor approved to treat hypertension. The renin-angiotensin system has been shown to be a significant contributor to the development of hypercholesterolemia-induced atherosclerosis. The aim of this study was to evaluate the antiatherosclerotic and plaque stabilization effects of aliskiren alone and in combination with atorvastatin.. APOE*3Leiden.CETP mice (n = 14-17/group) were fed a western-type diet (containing 0.25% cholesterol) alone or were treated with either aliskiren (15 mg/kg per day), atorvastatin (3.6 mg/kg per day) or a combination of aliskiren and atorvastatin. Effects on SBP, total cholesterol, inflammation markers and atherosclerotic size and composition were assessed.. Aliskiren reduced SBP (-19%, P < 0.001) and atorvastatin reduced total cholesterol (-24%, P < 0.001). Atherosclerotic lesion area was reduced by aliskiren (-40%, P < 0.01), atorvastatin (-61%, P < 0.001) and the combination treatment (-69%, P < 0.001). Aliskiren alone and together with atorvastatin decreased the number of T cells in the aortic root area (-60%, P < 0.01; -41%, P < 0.05), as well as macrophage (-64%, P < 0.001; -72%, P < 0.001) and necrotic area (-52%, P = 0.071; -84%, P < 0.001) in the lesion. Atorvastatin alone and together with aliskiren decreased monocyte adherence (-43%, P < 0.05 and -51%, P < 0.01) and monocyte chemoattractant protein-1 (both -36%, P < 0.01). The combination treatment decreased the number of lesions (-17%, P < 0.05) and E-selectin (-17%, P < 0.05).. Aliskiren inhibited atherosclerosis development and improved plaque stability alone and in combination with atorvastatin, possibly via a mechanism involving T cells. These results suggest a potential benefit of using aliskiren in a clinical setting, particularly in combination with statin treatment.

Topics: Amides; Animals; Apolipoproteins E; Atherosclerosis; Atorvastatin; Female; Fumarates; Heptanoic Acids; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Mice; Mice, Transgenic; Pyrroles

Topics: Amides; Animals; Apolipoproteins E; Atherosclerosis; Atorvastatin; Female; Fumarates; Heptanoic Acids; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Pyrroles

Although vitamin D has been implicated in cardiovascular protection, few studies have addressed the role of vitamin D receptor (VDR) in atherosclerosis. Here we investigate the effect of inactivation of the VDR signaling on atherogenesis and the antiatherosclerotic mechanism of vitamin D. Low density lipoprotein receptor (LDLR)(-/-)/VDR(-/-) mice exhibited site-specific accelerated atherogenesis, accompanied by increases in adhesion molecules and proinflammatory cytokines in the aorta and cholesterol influx in macrophages. Macrophages showed marked renin up-regulation in the absence of VDR, and inhibition of renin by aliskiren reduced atherosclerosis in LDLR(-/-)/VDR(-/-) mice, suggesting that the renin-angiotensin system (RAS) promotes atherosclerosis in the absence of VDR. LDLR(-/-) mice receiving LDLR(-/-)/VDR(-/-) BMT developed larger lesions than LDLR(-/-) BMT controls. Moreover, LDLR(-/-) mice receiving Rag-1(-/-)/VDR(-/-) BMT, which were unable to generate functional T and B lymphocytes, still had more severe atherosclerosis than Rag-1(-/-) BMT controls, suggesting a critical role of macrophage VDR signaling in atherosclerotic suppression. Aliskiren treatment eliminated the difference in lesions between Rag-1(-/-)/VDR(-/-) BMT and Rag-1(-/-) BMT recipients, indicating that local RAS activation in macrophages contributes to the enhanced atherogenesis seen in Rag-1(-/-)/VDR(-/-) BMT mice. Taken together, these observations provide evidence that macrophage VDR signaling, in part by suppressing the local RAS, inhibits atherosclerosis in mice.

Topics: Amides; Animals; Antihypertensive Agents; Aorta; Atherosclerosis; B-Lymphocytes; Bone Marrow Cells; Cell Adhesion Molecules; Cholesterol; Fumarates; Homeodomain Proteins; Lipids; Macrophages; Mice; Mice, Inbred C57BL; Mice, Knockout; Receptors, Calcitriol; Receptors, LDL; Renin; Renin-Angiotensin System; Signal Transduction; T-Lymphocytes; Up-Regulation

Sca-1 and VEGFR-2 positive pro-angiogenic cells (PAC) predict outcome of patients with vascular disease. Activation of the renin-angiotensin-aldosterone system impairs PAC function. The effects of the direct renin inhibitor aliskiren on PAC numbers and function are not known. Treatment of C57Bl/6 mice and Apo E(-/-) mice on high-cholesterol diet with aliskiren, 25 mg/kg/day s.c. for 3-6 weeks, reduced systolic and diastolic blood pressure by -11.5 and -13.7% compared to vehicle. Aliskiren increased Sca-1/VEGFR-2 positive PAC in the blood (159 ± 14%) and spleen-derived DiLDL/lectin positive PAC (180 ± 21%). Migratory capacity of PAC was increased to 165 ± 16%. In cultured human PAC, aliskiren dose-dependently increased the number of colony forming units to 152 ± 9% (1 μmol/l) and 187 ± 7% (10 μmol/l), which was prevented by the eNOS inhibitor LNMA. H₂O₂-induced apoptosis of cultured human PAC was reduced to 77 ± 23%. In Apo E(-/-) mice, aliskiren reduced atherosclerotic plaque area in the aortic sinus by 58 ± 4%. Circulating Sca-1/VEGFR-2 positive PAC were upregulated to 180 ± 25% and migratory capacity of PAC was increased to 127 ± 7%. Aliskiren reduced vascular NADPH oxidase activity to 41.6 ± 6.7%. Despite similar blood pressure lowering, treatment with hydralazine (25 mg/kg/day) did not significantly influence atherogenesis or PAC. Treatment of C57Bl/6 mice with a lower dose of aliskiren (15 mg/kg/day) did not affect blood pressure but increased cultured DiLDL/lectin positive PAC to 229 ± 30% and their migratory capacity to 214 ± 24%. Aliskiren increased number and function of PAC in mice and prevented atherosclerotic lesion formation. The effects were observed independent of blood pressure lowering.

Topics: Amides; Angiogenesis Inducing Agents; Animals; Antigens, Ly; Apolipoproteins E; Apoptosis; Atherosclerosis; Blood Pressure; Cell Movement; Cell Proliferation; Cells, Cultured; Disease Models, Animal; Endothelial Cells; Fumarates; Humans; Infusions, Subcutaneous; Male; Membrane Proteins; Mice; Mice, Inbred C57BL; Mice, Knockout; NADPH Oxidases; Neovascularization, Physiologic; Oxidative Stress; Renin; Stem Cells; Time Factors; Vascular Endothelial Growth Factor Receptor-2

The inhibition of renin-angiotensin system (RAS) has an effect beyond reducing blood pressure in the treatment of cardiovascular diseases; it also reduces mortality and morbidity. Although the classic RAS blockage is effective, due to blockage of negative feedback inhibition, it increases plasma renin activity and as a result generates a residual cardiovascular risk. Different from ACE-i and ARB treatments, aliskiren, a direct renin inhibitor, is the only pharmacologic agent that noticeably reduces the plasma renin activity, an independent cardiovascular risk factor. This creates a new option in RAS blockage. The efficacy and safety of aliskiren in the treatment of hypertension has been well established. The effect of aliskiren on cardiovascular mortality and morbidity is being researched. At this point there are many experimental and clinical studies to answer questions on this subject.

Topics: Amides; Antihypertensive Agents; Atherosclerosis; Cardiovascular Diseases; Fumarates; Humans; Hypertension; Renin; Renin-Angiotensin System

Topics: Amides; Animals; Antihypertensive Agents; Atherosclerosis; Fumarates; Humans; Hypertension; Nitric Oxide

We investigated whether aliskiren, a direct renin inhibitor, improves NO bioavailability and protects against spontaneous atherosclerotic changes. We also examined the effects of cotreatment with aliskiren and valsartan, an angiotensin II receptor blocker, on the above-mentioned outcomes. Watanabe heritable hyperlipidemic rabbits were treated with vehicle (control), aliskiren, valsartan, or aliskiren plus valsartan for 8 weeks. Then, acetylcholine-induced NO production was measured as a surrogate index of endothelium protective function, and both superoxide and vascular peroxynitrite were measured. Tetrahydrobiopterin in aortic segments was assessed by high-performance liquid chromatography with fluorescence detection. Plaque area was quantified by histology. Increase in plasma NO concentration in response to intra-aortic acetylcholine infusion was significantly greater in all of the test groups than in controls. Aliskiren+valsartan cotreatment increased acetylcholine-induced NO by 6.2 nmol/L, which was significantly higher than that with either aliskiren or valsartan alone. Vascular superoxide and peroxynitrite levels were both significantly higher in controls and significantly lower in the aliskiren+valsartan group than in the aliskiren or valsartan group. The highest tetrahydrobiopterin levels were observed after aliskiren+valsartan cotreatment. Histology of the thoracic aorta revealed that the plaque area was significantly decreased with combination therapy compared with monotherapy. Treatment with a direct renin inhibitor has protective effects on endothelial function and atherosclerotic changes. Furthermore, cotreatment with a direct renin inhibitor and an angiotensin II receptor blocker has additive protective effects on both.

Topics: Acetylcholine; Amides; Animals; Antihypertensive Agents; Atherosclerosis; Biopterins; Blood Pressure; Drug Therapy, Combination; Endothelium, Vascular; Fumarates; Heart Rate; HSP90 Heat-Shock Proteins; Hyperlipidemias; Inflammation Mediators; Lipids; Male; Nitric Oxide; Nitric Oxide Synthase Type III; Oxidative Stress; Proto-Oncogene Proteins c-akt; Rabbits; Renin; Tetrazoles; Tyrosine; Valine; Valsartan; Vasodilation; Vasodilator Agents

The role of the renin angiotensin system (RAS) in atherosclerosis is complex because of the involvement of multiple peptides and receptors. Renin is the rate-limiting enzyme in the production of all angiotensin peptides. To determine the effects of renin inhibition on atherosclerosis, we administered the novel renin inhibitor aliskiren over a broad dose range to fat-fed LDL receptor-deficient (Ldlr(-/-)) mice. Renin inhibition resulted in striking reductions of atherosclerotic lesion size in both the aortic arch and the root. Subsequent studies demonstrated that cultured macrophages expressed all components of the RAS. To determine the role of macrophage-derived angiotensin in the development of atherosclerosis, we transplanted renin-deficient bone marrow to irradiated Ldlr(-/-) mice and observed a profound decrease in the size of atherosclerotic lesions. In similar experiments, transplantation of bone marrow deficient for angiotensin II type 1a receptors failed to influence lesion development. We conclude that renin-dependent angiotensin production in macrophages does not act in an autocrine/paracrine manner. Furthermore, in vitro studies demonstrated that coculture with renin-expressing macrophages augmented monocyte adhesion to endothelial cells. Therefore, although previous work suggests that angiotensin peptides have conflicting effects on atherogenesis, we found that renin inhibition profoundly decreased lesion development in mice.

Topics: Amides; Animals; Atherosclerosis; Bone Marrow Transplantation; Cell Adhesion; Cells, Cultured; Fumarates; Hypercholesterolemia; Macrophages; Mice; Mice, Inbred C57BL; Monocytes; Receptor, Angiotensin, Type 1; Receptors, LDL; Renin; Systole

Hypertension is associated with increased risk of cardiovascular diseases. Antihypertensive treatment, particularly blockade of the renin-angiotensin system, contributes to prevent atherosclerosis-mediated cardiovascular events. Direct comparison of different antihypertensive treatments on atherosclerosis and particularly plaque stabilization is sparse. ApoE(-/-) mice with vulnerable (2-kidney, 1-clip renovascular hypertension model) or stable (1-kidney, 1-clip renovascular hypertension model) atherosclerotic plaques were used. Mice were treated with aliskiren (renin inhibitor), irbesartan (angiotensin-receptor blocker), atenolol (beta-blocker), or amlodipine (calcium channel blocker). Atherosclerosis characteristics were assessed. Hemodynamic and hormonal parameters were measured. Aliskiren and irbesartan significantly prevented atherosclerosis progression in 2-kidney, 1-clip mice. Indeed, compared with untreated animals, plaques showed thinner fibrous cap (P<0.05); smaller lipid core (P<0.05); decreased media degeneration, layering, and macrophage content (P<0.05); and increased smooth muscle cell content (P<0.05). Interestingly, aliskiren significantly increased the smooth muscle cell compared with irbesartan. Despite similar blood pressure lowering, only partial plaque stabilization was attained by atenolol and amlodipine. Amlodipine increased plaque smooth muscle cell content (P<0.05), whereas atenolol decreased plaque inflammation (P<0.05). This divergent effect was also observed in 1-kidney, 1-clip mice. Normalizing blood pressure by irbesartan increased the plasma renin concentration (5932+/-1512 ng/mL per hour) more than normalizing it by aliskiren (16085+/-5628 ng/mL per hour). Specific renin-angiotensin system blockade prevents atherosclerosis progression. First, evidence is provided that direct renin inhibition mediates atherosclerotic plaque stabilization. In contrast, beta-blocker and calcium channel blocker treatment only partially stabilize plaques differently influencing atherogenesis. Angiotensin II decisively mediates plaque vulnerability. The plasma renin concentration measurement by an indirect method did not confirm the excessive increase of plasma renin concentration reported in the literature during aliskiren compared with irbesartan or amlodipine treatment.

Topics: Amides; Amlodipine; Animals; Antihypertensive Agents; Apolipoproteins E; Atenolol; Atherosclerosis; Biphenyl Compounds; Blood Pressure; Cholesterol; Disease Models, Animal; Disease Progression; Female; Fumarates; Heart Rate; Irbesartan; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Renin; Renin-Angiotensin System; Tetrazoles

Topics: Amides; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Animals; Atherosclerosis; Fumarates; Humans; Mice; Mice, Knockout; Models, Biological; Receptors, LDL; Renin; Renin-Angiotensin System