Renin and renin blockade have no role in complement activity.

Renin, an aspartate protease, regulates the renin-angiotensin system by cleaving its only known substrate angiotensinogen to angiotensin. Recent studies have suggested that renin may also cleave complement component C3 to activate complement or contribute to its dysregulation. Typically, C3 is cleaved by C3 convertase, a serine protease that uses the hydroxyl group of a serine residue as a nucleophile. Here, we provide seven lines of evidence to show that renin does not cleave C3. First, there is no association between renin plasma levels and C3 levels in patients with C3 Glomerulopathies (C3G) and atypical Hemolytic Uremic Syndrome (aHUS), implying that serum C3 consumption is not increased in the presence of high renin. Second, in vitro tests of C3 conversion to C3b do not detect differences when sera from patients with high renin levels are compared to sera from patients with normal/low renin levels. Third, aliskiren, a renin inhibitor, does not block abnormal complement activity introduced by nephritic factors in the fluid phase. Fourth, aliskiren does not block dysregulated complement activity on cell surfaces. Fifth, recombinant renin from different sources does not cleave C3 even after 24 hours of incubation at 37 °C. Sixth, direct spiking of recombinant renin into sera samples of patients with C3G and aHUS does not enhance complement activity in either the fluid phase or on cell surfaces. And seventh, molecular modeling and docking place C3 in the active site of renin in a position that is not consistent with a productive ground state complex for catalytic hydrolysis. Thus, our study does not support a role for renin in the activation of complement.

Aliskiren-Loaded Nanoparticles Downregulate (Pro)renin Receptor and ACE Gene Expression in the Heart of Spontaneously Hypertensive Rats: Effect on NADPH Oxidase.

We aimed to determine effects of aliskiren, a direct renin inhibitor, loaded onto polymeric nanoparticles on the (pro)renin receptor (Atp6ap2), angiotensin II type 1 receptor (Agtr1), and angiotensin-converting enzyme (ACE) gene expression in the heart of spontaneously hypertensive rats (SHR). Twelve-week-old male SHRs were divided into an untreated group and groups treated with powdered aliskiren or aliskiren-loaded nanoparticles (25 mg/kg/day). After three weeks, the accumulation of aliskiren, distribution of polymeric nanoparticles, gene expression of Atp6ap2 and Agtr1 receptors and ACE, and protein expression of NADPH oxidase along with the conjugated diene (CD) concentration were analyzed. The accumulation of aliskiren in the heart was higher in the aliskiren-loaded nanoparticle group than in the powdered group. The fluorescent signals of nanoparticles were visible in cardiomyocytes, vessel walls, and erythrocytes. Aliskiren-loaded nanoparticles decreased the gene expression of Atp6ap2 and ACE, while not affecting Agtr1. Both forms of aliskiren decreased the protein expression of NADPH oxidase, with a more pronounced effect observed in the aliskiren-loaded nanoparticle group. CD concentration was decreased only in the aliskiren-loaded nanoparticle group. We hypothesize that aliskiren-loaded nanoparticle-mediated downregulation of Atp6ap2 and ACE may contribute to a decrease in ROS generation with beneficial effects in the heart. Moreover, polymeric nanoparticles may represent a promising tool for targeted delivery of aliskiren.

Novel therapeutic modalities target cell signaling of Renin-Angiotensin system/NF-κB-induced cell cycle arrest and apoptosis in urethane-induced lung cancer in mice: An in vivo study.

BACKGROUND: Lung cancer has risen to the top of the list of cancer-related deaths worldwide. Aliskiren is a direct renin inhibitor. AIM: This study aims to investigate the impact of cell signaling of Renin-Angiotensin system (RAS)/NF-κB on lung cancer by investigating the potential therapeutic effects of aliskiren for lung cancer treatment in urethane-induced lung cancer in mice. METHODS: Male BALB/c mice were randomly assigned to one of five treatment groups for 150 days, including (1) normal control; (2) aliskiren (25 mg/kg/i.p) daily, (3) urethane at a dose of 1.5 g/kg (i.p) at Day 1 and 60 (nonsmall cell lung cancer[NSCLC] group) (4) NSCLC mice received carboplatin (15 mg/kg/i.p) every other day for the last 4 successive weeks and (5) NSCLC mice treated with aliskiren daily. Tumor size was determined based on blood sampling, and lungs were isolated for biochemical analysis, western blot analysis assay, and histopathological examination. RESULTS: Urethane demonstrated significant changes in all biochemical and molecular parameters and histological patterns. Aliskiren-treated mice had significantly lower levels of NF-κB p65, Bcl-2, cyclin D1, ICAM-1, MMP-2, and Nrf2, with an increase in the catalytic activity of caspase-3 due to its RAS inhibitory mechanism. The combined urethane administration with aliskiren demonstrated a significant improvement in the histopathological examination. CONCLUSION: RAS/NF-B cell signaling is a potential therapeutic target for preventing and treating lung adenocarcinoma, evidenced by the fundamental cytotoxic mechanism and attenuation of metastasis and angiogenesis induced by the treatment of NSCLC mice with aliskiren.

Aliskiren Hemifumarate Proliposomes for Improved Oral Drug Delivery: Formulation Development, In Vitro and In Vivo Permeability Testing.

The objective of this study was to develop proliposomal formulations for a poorly bioavailable drug, aliskiren hemifumarate (AKH). A solvent evaporation method was used to prepare proliposomes using different lipids. The lipids of selection were soy phosphatidylcholine (SPC), dimyristoylphosphatidylcholine (DMPC), and dimyristoylphosphatidylglycerol sodium (DMPG Na), stearylamine, and cholesterol in various ratios. Proliposomes were evaluated for particle size, zeta potential, in vitro drug release, in vitro permeability, and in vivo pharmacokinetics upon hydration with aqueous phase. In vitro drug release studies were conducted in 0.01 N hydrochloric acid using USP type II dissolution apparatus. Parallel artificial membrane permeation assay (PAMPA) and Caco-2 cell line models were used to study the in vitro drug permeation. Male Sprague-Dawley (SD) rats were used to conduct in vivo pharmacokinetic studies. Among different formulations, proliposomes with drug/DMPC/cholesterol/stearylamine in the ratio of 1:5:0.025:0.050 (w/w/w/w) demonstrated the desired particle size, higher zeta potential, and higher encapsulation efficiency. The PAMPA and Caco-2 cell line experiments showed a significantly higher permeability of AKH with proliposomes as compared to pure AKH. In animal studies, the optimized formulation of proliposomes showed significant improvement in the rate and extent of absorption of AKH. Specifically, following a single oral administration, the relative bioavailability of AKH proliposome formulation was 230% when compared to pure AKH suspension.

Mechanistic insights on nsSNPs on binding site of renin and cytochrome P450 proteins: A computational perceptual study for pharmacogenomics evaluation.

Past several decades, therapeutic investigations lead to the discovery of numerous antihypertensive drugs. Although it has been proved for their potency, altered efficacy is common norms in several conditions due to genetic variations. Cytochrome P450 plays a crucial role in drug metabolism and responsible for the pharmacokinetic and pharmacodynamic properties of the drug molecules. Here, we report the deleterious point mutations in the genes associated with the altered response of antihypertensive drug molecules and their metabolizers. Missense variants were filtered as potential nonsynonymous single nucleotide polymorphisms among the available data for the target genes (REN, CYP2D6, CYP3A4). The key objective of the work is to identify the deleterious single nucleotide polymorphisms (SNPs) responsible for the drug response and metabolism for the application of personalized medication. The molecular docking studies revealed that Aliskiren and other clinically approved drug molecules have a high binding affinity with both wild and mutant structures of renin, CYP2D6, and CYP3A4 proteins. The docking (Glide XP) score was observed to have in the range of -8.896 to -11.693 kcal/mol. The molecular dynamics simulation studies were employed to perceive the structural changes and conformational deviation through various analyses. Each studied SNPs was observed to have disparate scoring in the binding affinity to the specific drug molecules. As a prospective plan, we assume this study might be applied to identify the risky SNPs associated with hypertension from the patients to recommend the suitable drug for personalized hypertensive treatment. Further, extensive clinical pharmacogenomics studies are required to support the findings.

Attenuation of atrial remodeling by aliskiren via affecting oxidative stress, inflammation and PI3K/Akt signaling pathway.

INTRODUCTION: Atrial fibrillation (AF) is the most common type of arrhythmia. Atrial remodeling is a major factor to the AF substrate. The purpose of the study is to explore whether aliskiren (ALS) has a cardioprotective effect and its potential molecular mechanisms on atrial remodeling. METHODS: In acute experiments, dogs were randomly assigned to Sham, Paced and Paced+aliskiren (10 mg kg-1) (Paced+ALS) groups, with 7 dogs in each group. Rapid atrial pacing (RAP) was maintained at 600 bpm for 2 h for paced and Paced+ALS groups and atrial effective refractory periods (AERPs), inducibility of AF (AFi) and average duration time (ADT) were measured. In chronic experiments, there were 5 groups: Sham, Sham+ALS, Paced, Paced+ALS and Paced+ALS+PI3K antagonist wortmannin (WM) (70 µg kg-1 day-1). RAP at 500 beats/min was maintained for 2 weeks. Inflammation and oxidative stress indicators were measured by ELISA assay, echocardiogram and pathology were used to assess atrial structural remodeling, phosphatidylinositol 3-hydroxy kinase/protein kinase B (PI3K/Akt) signaling pathways were studied by RT-PCR and western blotting to evaluate whether the cardioprotective effect of ALS works through PI3K/Akt signaling pathway. RESULTS: The electrophysiological changes were observed after 2-h pacing. The AERP shortened with increased AFi and ADT, which was attenuated by ALS (P < 0.05). After pacing for 2 weeks, oxidative stress and inflammation markers in the Paced group were significantly higher than those in the Sham group (P < 0.01) and were reduced by ALS treatment (P < 0.01). The reduced level of antioxidant enzymes caused by RAP was also found to be elevated in ALS-treated group (P < 0.01). The results of pathology and echocardiography showed that RAP can cause atrial enlargement, fibrosis (P < 0.01), and were attenuated in ALS treatment group. The PI3K/Akt signaling pathway were downregulated induced by RAP. ALS could upregulate the PI3K/Akt pathway expression (P < 0.05). Furthermore, the cardioprotective effects in structural remodeling of ALS were suppressed by WM. CONCLUSIONS: ALS may offer cardioprotection in RAP-induced atrial remodeling, which may partly be ascribed to its anti-inflammatory and anti-oxidative stress action and the regulation of PI3K/Akt signaling pathway.

Aliskiren and captopril improve cognitive deficits in poorly controlled STZ-induced diabetic rats via amelioration of the hippocampal P-ERK, GSK3ß, P-GSK3ß pathway.

Learning and memory deficits are obvious symptoms that develop over time in patients with poorly controlled diabetes. Hyperactivity of the renin-angiotensin system (RAS) is directly associated with ß-cell dysfunction and diabetic complications, including cognitive impairment. Here, we investigated the protective and molecular effects of two RAS modifiers, aliskiren; renin inhibitor and captopril; angiotensin converting enzyme inhibitor, on cognitive deficits in the rat hippocampus. Injection of low dose streptozotocin for 4 days resulted in type 1 diabetes. Then, poorly controlled diabetes was mimicked with ineffective daily doses of insulin for 4 weeks. The hyperglycaemia and pancreatic atrophy caused memory disturbance that were identifiable in behavioural tests, hippocampal neurodegeneration, and the following significant changes in the hippocampus, increases in the inflammatory marker interleukin 1ß, cholinesterase, the oxidative stress marker malondialdehyde and protein expression of phosphorylated extracellular-signal-regulated kinase and glycogen synthase kinase-3 beta versus decrease in the antioxidant reduced glutathione and protein expression of phosphorylated glycogen synthase kinase-3 beta. Blocking RAS with either drugs along with insulin amended all previously mentioned parameters. Aliskiren stabilized the blood glucose level and restored normal pancreatic integrity and hippocampal malondialdehyde level. Aliskiren showed superior protection against the hippocampal degeneration displayed in the earlier behavioural modification in the passive avoidance test, and the aliskiren group outperformed the control group in the novel object recognition test. We therefore conclude that aliskiren and captopril reversed the diabetic state and cognitive deficits in rats with poorly controlled STZ-induced diabetes through reducing oxidative stress and inflammation and modulating protein expression.

Decades-old renin inhibitors are still struggling to find a niche in antihypertensive therapy. A fleeting look at the old and the promising new molecules.

Hypertension is a diverse illness interlinked with cerebral, cardiovascular (CVS) and renal abnormalities. Presently, the malady is being treated by focusing on Renin- angiotensin system (RAS), voltage-gated calcium channels, peripheral vasodilators, renal and sympathetic nervous systems. Cardiovascular and renal abnormalities are associated with the overactivation of RAS, which can be constrained by angiotensin- converting enzyme inhibitors (ACEIs), angiotensin II (Ang-II) -AT1 receptor blockers (ARBs) and renin inhibitors. The latter is a new player in the old system. The renin catalyzes the conversion of angiotensinogen to Angiotensin I (Ang-I). This can be overcome by inhibiting renin, a preliminary step, eventually hinders the occurrence of the cascade of events in the RAS. Various peptidomimetics, the first-generation renin inhibitors developed six decades ago have limited drug-like properties as they suffered from poor intestinal absorption, high liver first-pass metabolism and low oral bioavailability. The development of chemically diverse molecules from peptides to nonpeptides expanded the horizon to achieving direct renin inhibition. Aliskiren, a blockbuster drug that emerged as a clinical candidate and got approved by the US FDA in 2007 was developed by molecular modeling studies. Aliskiren indicated superior to average efficacy and with minor adverse effects relative to other RAS inhibitors. However, its therapeutic use is limited by poor oral bioavailability of less than 2% that is similar to first-generation peptidic compounds. In this review, we present the development of direct renin inhibitors (DRIs) from peptidic to nonpeptidics that lead to the birth of aliskiren, its place in the treatment of cardiovascular diseases and its limitations.

Clinical efficacy, safety and tolerability of Aliskiren Monotherapy (AM): an umbrella review of systematic reviews.

BACKGROUND: Aliskiren is a newly developed drug. Its role in lowering BP has been recognized. However, the role of aliskiren in treating heart and renal diseases are still controversial. OBJECTIVE: To evaluate the existing evidence about clinical efficacy, safety and tolerability of aliskiren monotherapy (AM). METHODS: An umbrella review of systematic reviews of interventional studies. We searched Pubmed, Embase and Cochrane Library up to June 2019. Two reviewers applied inclusion criteria to the select potential articles independently. The extract and analyze of accessible data were did by two reviewers independently too. Discrepancies were resolved with discussion or the arbitration of the third author. RESULTS: Eventually, our review identified 14 eligible studies. Results showed that for essential hypertension patients, aliskiren showed a great superiority over placebo in BP reduction, BP response rate and BP control rate. Aliskiren and placebo, ARBs or ACEIs showed no difference in the number or extent of adverse events. For heart failure patients, AM did not reduce BNP levels (SMD -0.08, - 0.31 to 0.15) or mortality rate (RR 0.76, 0.32 to 1.80), but it decreased NT-proBNP (SMD -0.12, - 0.21 to - 0.03) and PRA levels (SMD 0.52, 0.30 to 0.75), increased PRC levels (SMD -0.66, - 0.8 to - 0.44). For patients who are suffered from hypertension and diabetes and/or nephropathy or albuminuria at the same time, aliskiren produced no significant effects (RR 0.97, 0.81 to 1.16). CONCLUSION: We found solid evidence to support the benefits of aliskiren in the treatment of essential hypertension, aliskiren can produce significant effects in lowering BP and reliable safety. However, the effects of aliskiren in cardiovascular and renal outcomes were insignificant. TRIAL REGISTRATION: Study has been registered in PROSPERO (CRD42019142141).

Add-on aliskiren treatment can decrease blood pressure but requires attention to risks of renal impairment and hyperkalemia Chikushi Anti-Hypertension Trial-Rasilez® (CHAT-Ras).

BACKGROUND: Renin is the starting point of the renin angiotensin (RA) system cycle. Aliskiren (AL), which is a direct renin inhibitor, suppressed the entire RA cycle. In the present study, the efficacy of add-on of AL treatment in patients with essential hypertension (HT) was investigated. METHODS: This study was a multi-center, open-label, prospective, observational study. Study subjects were patients with essential HT and poor blood pressure (BP) control, who had received calcium channel blocker monotherapy or angiotensin II receptor blocker monotherapy or had not received any BP lowering drugs. Following add-on of AL for 12 months, BP and additional laboratory findings were analyzed. RESULTS: A total of 150 subjects were enrolled. There were 50 dropout subjects including discontinuation. Dropouts were the highest in the ARB combination therapy group at 9 subjects due to adverse events, and 3 of them were due to hyperkalemia. A significantly higher number of patients with chronic kidney disease (CKD) dropped out compared to patients without CKD (φ = 0.166, p < .05). BP before add-on of AL was 155/88 mmHg. After add-on of AL, BP was significantly improved and this lowering was sustained for 3 months (136/78 mmHg, p < .001), 6 months (136/77 mmHg, p < .001) and 12 months (134/78 mmHg, p < .001). In contrast, add-on of AL increased the potassium level and decreased the estimated glomerular filtration rate. CONCLUSION: While add-on AL treatment achieved a favorable and sustained decrease of BP in this study, caution is necessary with regard to elevation of potassium levels and renal impairment.

The use of aliskiren as an antifibrotic drug in experimental models: A systematic review.

Aliskiren is an oral antihypertensive medication that acts by directly inhibiting renin. High levels of circulating renin and prorenin activate the pathological signaling pathway of fibrosis. This drug also reduces oxidative stress. Thus, the aim of this systematic review is to analyze experimental studies that show the actions of aliskiren on fibrosis. PubMed and LILACS databases were consulted using the keywords aliskiren and fibrosis within the period between 2005 and 2017. Fifty-three articles were analyzed. In the heart, aliskiren attenuated remodeling, hypertrophy, inflammatory cytokines, collagen deposition, and oxidative stress. In the kidneys, there was a reduction in interstitial fibrosis, the infiltration of inflammatory cells, apoptosis, proteinuria, and in the recruitment of macrophages. In diabetic models, an improvement in the albumin/creatinine relationship and in the insulin pathway in skeletal muscles was observed; aliskiren was beneficial to pancreatic function and glucose tolerance. In the liver, aliskiren reduced fibrosis, steatosis, inflammatory cytokines, and collagen deposition. In the lung and peritoneal tissues, there was a reduction in fibrosis. Many studies have reported on the beneficial effects of aliskiren on endothelial function and arterial rigidity. A reduction in fibrosis in different organs is cited by many authors, which complies with the results found in this review. However, studies diverge on the use of the drug in diabetic patients. Aliskiren has antifibrotic potential in several experimental models, interfering with the levels of fibrogenic cytokines and oxidative stress. Therefore, its use in diseases in which fibrosis plays an important pathophysiological role is suggested.

[Preliminary clinical analysis of direct renin inhibitor aliskiren in the treatment of severe coronavirus disease 2019 patients with hypertension].

Objective: To explore the feasibility of direct renin inhibitor aliskiren for the treatment of severe or critical coronavirus disease 2019 (COVID-19) patients with hypertension. Methods: The antihypertensive effects and safety of aliskiren was retrospectively analyzed in three severe and one critical COVID-19 patients with hypertension. Results: Four patients, two males and two females, with an average age of 78 years (66-87 years), were referred to hospital mainly because of respiratory symptoms. Three were diagnosed by positive novel coronavirus 2019 (2019-nCoV) nucleic acid or antibody, and the critical patient with cardiac insufficiency was clinically determined. Two patients were treated with calcium channel antagonist (CCB), one with angiotensin converting enzyme inhibitor (ACEI), and one with angiotensin Ⅱ receptor antagonist (ARB). After admission, ACEI and ARB were discontinued, one patient with heart failure was treated by aliskiren combined with diuretic.Three patients were treated with aliskiren combined with CCB among whom two withdrew CCB due to low blood pressure after 1 to 2 weeks. Based on comprehensive treatment including antiviral and oxygenation treatment, blood pressure was satisfactorily controlled by aliskiren after three to four weeks without serious adverse events. All patients were finally discharged. Conclusion: Our preliminary clinical data shows that antihypertensive effect of aliskiren is satisfactory and safe for severe COVID-19 patients complicated with hypertension.

Aliskiren, tadalafil, and cinnamaldehyde alleviate joint destruction biomarkers; MMP-3 and RANKL; in complete Freund's adjuvant arthritis model: Downregulation of IL-6/JAK2/STAT3 signaling pathway.

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease, which is accompanied by progressive joint damage and disability. The intolerability of conventional antirheumatic drugs by some patients necessitates the search for effective antirheumatic agents having better tolerability. In the current work, we aimed to investigate the efficacy of cinnamaldehyde, tadalafil, and aliskiren as potential antirheumatic candidates and to explore their modulatory effects on joint destruction, inflammatory response, and intracellular signaling. Arthritis was induced in female Wistar rats by complete Freund's adjuvant (CFA) 0.4 ml s.c. on days 1, 4, and 7. Treated groups received their respective drugs, starting from day 13, daily for 3 weeks. Methotrexate and prednisolone were the standard antirheumatic drugs, while cinnamaldehyde, tadalafil, and aliskiren were the test agents. Treatment with cinnamaldehyde, tadalafil, or aliskiren reduced serum levels of rheumatoid factor, and pro-inflammatory cytokines; tumor necrosis factor-alpha and interleukin-6 (IL-6), along with elevated level of IL-10 which is an anti-inflammatory cytokine. Besides, cartilage and bone destruction biomarkers; matrix metalloproteinase-3 (MMP-3) and receptor activator of nuclear factor-kappa B ligand (RANKL); were significantly reduced after treatment with the test agents, which was further confirmed by histopathological investigation. The elevated protein expressions of phosphorylated-Janus kinase 2 (p-JAK2), phosphorylated-signal transducer and activator of transcription 3 (p-STAT3), and inducible nitric oxide synthase (iNOS) in articular tissue were markedly attenuated after treatment with cinnamaldehyde, tadalafil, or aliskiren, while that of endothelial nitric oxide synthase (eNOS) was greatly enhanced. In addition, oxidative stress and inflammatory markers such as malondialdehyde, nitric oxide, and myeloperoxidase were reduced in joint tissue after treatment with the test agents, while glutathione content was elevated. Furthermore, the renin inhibitor aliskiren produced effects close to those of the normal and methotrexate, the gold standard antirheumatic drug, in most of the measured parameters. Collectively, these findings led to the assumption that the downregulation of IL-6/JAK2/STAT3 signaling by cinnamaldehyde, tadalafil, and aliskiren could alleviate joint destruction by MMP-3 and RANKL, reduce iNOS, and enhance eNOS expressions. Moreover, aliskiren could be a promising therapeutic agent for RA, because of its ability to normalize most of the measured parameters after CFA-induced arthritis.

Normalizing Plasma Renin Activity in Experimental Dilated Cardiomyopathy: Effects on Edema, Cachexia, and Survival.

Heart failure (HF) patients frequently have elevated plasma renin activity. We examined the significance of elevated plasma renin activity in a translationally-relevant model of dilated cardiomyopathy (DCM), which replicates the progressive stages (A-D) of human HF. Female mice with DCM and elevated plasma renin activity concentrations were treated with a direct renin inhibitor (aliskiren) in a randomized, blinded fashion beginning at Stage B HF. By comparison to controls, aliskiren treatment normalized pathologically elevated plasma renin activity (p < 0.001) and neprilysin levels (p < 0.001), but did not significantly alter pathological changes in plasma aldosterone, angiotensin II, atrial natriuretic peptide, or corin levels. Aliskiren improved cardiac systolic function (ejection fraction, p < 0.05; cardiac output, p < 0.01) and significantly reduced the longitudinal development of edema (extracellular water, p < 0.0001), retarding the transition from Stage B to Stage C HF. The normalization of elevated plasma renin activity reduced the loss of body fat and lean mass (cachexia/sarcopenia), p < 0.001) and prolonged survival (p < 0.05). In summary, the normalization of plasma renin activity retards the progression of experimental HF by improving cardiac systolic function, reducing the development of systemic edema, cachexia/sarcopenia, and mortality. These data suggest that targeting pathologically elevated plasma renin activity may be beneficial in appropriately selected HF patients.

Protective Effects of Nanoparticle-Loaded Aliskiren on Cardiovascular System in Spontaneously Hypertensive Rats.

Aliskiren, a renin inhibitor, has been shown to have cardioprotective and blood pressure (BP) lowering effects. We aimed to determine the effects of nanoparticle-loaded aliskiren on BP, nitric oxide synthase activity (NOS) and structural alterations of the heart and aorta developed due to spontaneous hypertension in rats. Twelve week-old male spontaneously hypertensive rats (SHR) were divided into the untreated group, group treated with powdered or nanoparticle-loaded aliskiren (25 mg/kg/day) and group treated with nanoparticles only for 3 weeks by gavage. BP was measured by tail-cuff plethysmography. NOS activity, eNOS and nNOS protein expressions, and collagen content were determined in both the heart and aorta. Vasoactivity of the mesenteric artery and wall thickness, inner diameter, and cross-sectional area (CSA) of the aorta were analyzed. After 3 weeks, BP was lower in both powdered and nanoparticle-loaded aliskiren groups with a more pronounced effect in the latter case. Only nanoparticle-loaded aliskiren increased the expression of nNOS along with increased NOS activity in the heart (by 30%). Moreover, nanoparticle-loaded aliskiren decreased vasoconstriction of the mesenteric artery and collagen content (by 11%), and CSA (by 25%) in the aorta compared to the powdered aliskiren group. In conclusion, nanoparticle-loaded aliskiren represents a promising drug with antihypertensive and cardioprotective effects.

Aliskiren inhibits renin-mediated complement activation.

Certain kidney diseases are associated with complement activation although a renal triggering factor has not been identified. Here we demonstrated that renin, a kidney-specific enzyme, cleaves C3 into C3b and C3a, in a manner identical to the C3 convertase. Cleavage was specifically blocked by the renin inhibitor aliskiren. Renin-mediated C3 cleavage and its inhibition by aliskiren also occurred in serum. Generation of C3 cleavage products was demonstrated by immunoblotting, detecting the cleavage product C3b, by N-terminal sequencing of the cleavage product, and by ELISA for C3a release. Functional assays showed mast cell chemotaxis towards the cleavage product C3a and release of factor Ba when the cleavage product C3b was combined with factor B and factor D. The renin-mediated C3 cleavage product bound to factor B. In the presence of aliskiren this did not occur, and less C3 deposited on renin-producing cells. The effect of aliskiren was studied in three patients with dense deposit disease and this demonstrated decreased systemic and renal complement activation (increased C3, decreased C3a and C5a, decreased renal C3 and C5b-9 deposition and/or decreased glomerular basement membrane thickness) over a follow-up period of four to seven years. Thus, renin can trigger complement activation, an effect inhibited by aliskiren. Since renin concentrations are higher in renal tissue than systemically, this may explain the renal propensity of complement-mediated disease in the presence of complement mutations or auto-antibodies.

Arterial wall hypertrophy is ameliorated by α2-adrenergic receptor antagonist or aliskiren in kidneys of angiotensinogen-knockout mice.

BACKGROUND: Arterial hypertrophy and interstitial fibrosis are important characteristics in kidneys of angiotensinogen-knockout (Atg -/-) mice. In these mice, which exhibit polyuria and hypotension, sympathetic nerve signaling is estimated to be compensatorily hyperactive. Furthermore, transforming growth factor (TGF)-ß1 is overexpressed in mice kidneys. To determine whether sympathetic nerve signaling and TGF-ß1 exacerbate arterial hypertrophy and interstitial fibrosis, intervention studies of such signaling are required. METHODS: We performed renal denervation and administered the α2-adrenergic receptor (AR) antagonist, atipamezole, to Atg -/- mice. A renin inhibitor, aliskiren, which was preliminarily confirmed to reduce TGF-ß1 gene expression in kidneys of the mice, was additionally administered to assess the effect on the arterial hypertrophy and interstitial fibrosis. RESULTS: Norepinephrine content in kidneys of Atg -/- mice was three times higher than in kidneys of wild-type mice. Interventions by renal denervation and atipamezole resulted in amelioration of the histological findings. Overexpression of TGF-ß1 gene in kidneys of Atg -/- mice was altered in a manner linked to the histological findings. Surprisingly, aliskiren reduced α2-AR gene expression, interstitial fibrosis, and arterial hypertrophy in kidneys of Atg -/- mice, which lack renin substrate. CONCLUSIONS: Alpha2-AR signaling is one of the causes of persistent renal arterial hypertrophy in Atg -/- mice. Aliskiren also angiotensinogen-independently reduces the extent of renal arterial hypertrophy, partly thorough downregulation of α2-ARs. Although renal arterial hypertrophy in Atg -/- mice appears to be of multifactorial origin, TGF-ß1 may play a key role in the persistence of such hypertrophy.

The comparative efficacy of renin-angiotensin system blockers in schistosomal hepatic fibrosis.

Schistosomiasis mansoni is involved in hepatic fibrogenesis and portal hypertension. Previous studies proved that blockade of some components of the renin-angiotensin system (RAS) reduce liver fibrogenesis. However, the effects of inhibition of early stages of RAS pathway in schistosomal fibrosis have not been studied yet. Thus, the aim of this study was to compare the role of different antihypertensive drugs on hepatic fibrosis in murine schistosomiasis. BALB/c mice (n = 50) weighing 20g were subjected to inoculation of 50 cercariae and submitted to different treatments: aliskiren, 50 mg/kg (n = 10); bradykinin, 2 µg/kg (n = 5); losartan, 10 mg/kg (n = 10); lisinopril 10 mg/kg (n = 5) and control, proportional volume vehicle (n = 5); daily for 14 weeks. Six animals were not subjected to cercariae inoculation or any type of treatment. Ultrasound, histological, immunohistochemical and proteomic analyzes were performed to evaluate markers associated with hepatic fibrogenesis. The hepatic areas stained with Sirius red and thenumber of cells marked by α-SMA in animals treated with aliskiren, bradykinin, lisinopril and losartan were diminished when compared to control group, demonstrating reduced hepatic fibrosis after RAS blockade. These results were reinforced by ultrasonography analysis and protein expression of TGFß. These findings demonstrated the effect of RAS inhibition on hepatic fibrosis in murine schistosomiasis, with the most evident results being observed in the losartan and aliskiren treated groups. The main mechanisms underlying this process appear to involve anti-fibrogenic activity through the inhibition of collagen and TGFß synthesis.

Aliskiren and valsartan in combination is a promising therapy for hypertensive renal injury in rats.

Neither ACEI nor ARBs completely repress the RAAS. Aliskiren is a newer agent that inhibits renin. However, it increases the biosynthesis and secretion of renin and prorenin, that might induce renal tissue damage. This study was conducted to investigate the renoprotective effects of aliskiren and valsartan the ARB, either alone or in combination, on hypertensive nephropathy induced by L-NAME. Aliskiren (50 mg/kg/daily i.p.), valsartan (10 mg/kg daily i.p.) alone or in half dose combination were administered with L-NAME (30-40 mg daily in drinking water) for 8 weeks. Aliskiren and valsartan significantly reduced systolic blood pressure, proteinuria, serum creatinine, blood urea nitrogen, oxidative stress, and structural renal injury although not to the same extent. Valsartan reduced systolic blood pressure and proteinuria in L-NAME treated rats more significantly than aliskiren. However, glomerular collapse index and the expansion of interstitial tissue were significantly attenuated by aliskiren than by valsartan. Cotreatment with aliskiren and valsartan markedly reduced the oxidative stress and further reduced the glomerular collapse and the expansion of interstitial tissue compared with aliskiren monotherapy. CONCLUSION: These results suggest that therapies aimed at different targets within the RAAS may have additional effects in attenuating structural injury in experimental hypertensive nephropathy.

Aliskiren decreases oxidative stress and angiogenic markers in retinal pigment epithelium cells.

There is growing evidence on the role of ocular renin-angiotensin system (RAS) in the development of diabetic retinopathy (DR), particularly due to the trigger of oxidative stress and angiogenesis. Despite this there is no effective RAS-based therapy in DR capable of preventing retinal damage induced by RAS activation. We recently described that retinal pigment epithelium (RPE) cells express the main components of the RAS. We here propose to investigate the role of glucose upon the retinal RAS and whether aliskiren, a direct renin inhibitor, protects RPE cells from angiogenesis and oxidative stress. RPE cells were chosen as target since one of the first events in DR is the dysfunction of the RPE retinal layer, which as a key function in maintaining the integrity of the retina. We found that the RAS present in the RPE cells was deregulated by hyperglycemic glucose concentrations. Exposure of RPE cells to angiotensin II increased the levels of the main pro-angiogenic factor, vascular endothelial growth factor (VEGF) in a concentration-dependent manner. Additionally, angiotensin II also stimulated the production of reactive oxygen species in RPE cells. Treatment of RPE cells with aliskiren decreased the levels of oxidative stress and promoted the expression of anti-angiogenic factors such as the pigment epithelium-derived factor and the VEGF165b isoform. Our findings demonstrate that the RAS is deregulated in hyperglycemic conditions and that aliskiren successfully protected RPE cells from RAS over activation. These anti-angiogenic and antioxidant properties described for aliskiren over RPE cells suggest that this drug has potential to be used in the treatment of diabetic retinopathy.