aliskiren and Hypercholesterolemia

The three main causes of Chronic Kidney Diseases [CKD] are diabetes mellitus, chronic glomerulonephritis and hypertension. CKD is an increasing burden in the community as more patients fall prey to kidney failure. Both dialysis and renal transplantation are expensive modalities of treatment for end stage renal failure [ESRF]. Through the years many clinical trials have been performed to retard the progression of CKD to ESRF. Most of the trials focus on three main strategies which aim at renal retardation, namely, control of hypertension, treatment of proteinuria and control of hypercholesterolaemia. More recently, investigators have been exploring the role of high dose ARBs as well as the use of Aliskiren, a renin inhibitor. Early therapeutic intervention is necessary as it will contribute to better chances of minimising glomerular damage and in the case of some, even lead to the improvement of renal function with regression of glomerulosclerosis.

Topics: Amides; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Antihypertensive Agents; Clinical Trials as Topic; Combined Modality Therapy; Drug Therapy, Combination; Fumarates; Humans; Hypercholesterolemia; Hypertension; Kidney Failure, Chronic; Losartan; Proteinuria; Renal Replacement Therapy

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

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