Upregulation of angiotensin II-AT1 receptors during statin withdrawal in vascular smooth muscle cells

Interactions between Angiotensin Type-1 Antagonists, Statins, and ROCK Inhibitors in a Rat Model of L-DOPA-Induced Dyskinesia

Statins have been proposed for L-DOPA-induced dyskinesia (LID) treatment. Statin anti-dyskinetic effects were related to the inhibition of the Ras-ERK pathway. However, the mechanisms responsible for the anti-LID effect are unclear. Changes in cholesterol homeostasis and oxidative stress- and inflammation-related mechanisms such as angiotensin II and Rho-kinase (ROCK) inhibition may be involved. The nigra and striatum of dyskinetic rats showed increased levels of cholesterol, ROCK, and the inflammatory marker IL-1β, which were reduced by the angiotensin type-1 receptor (AT1) antagonist candesartan, simvastatin, and the ROCK inhibitor fasudil. As observed for LID, angiotensin II-induced, via AT1, increased levels of cholesterol and ROCK in the rat nigra and striatum. In cultured dopaminergic neurons, angiotensin II increased cholesterol biosynthesis and cholesterol efflux without changes in cholesterol uptake. In astrocytes, angiotensin induced an increase in cholesterol uptake, decrease in biosynthesis, and no change in cholesterol efflux, suggesting a neuronal accumulation of cholesterol that is reduced via transfer to astrocytes. Our data suggest mutual interactions between angiotensin/AT1, cholesterol, and ROCK pathways in LID, which are attenuated by the corresponding inhibitors. Interestingly, these three drugs have also been suggested as neuroprotective treatments against Parkinson's disease. Therefore, they may reduce dyskinesia and the progression of the disease using common mechanisms.

Effects of Statins on Renin-Angiotensin System

Statins, a class of drugs for lowering serum LDL-cholesterol, have attracted attention because of their wide range of pleiotropic effects. An important but often neglected effect of statins is their role in the renin-angiotensin system (RAS) pathway. This pathway plays an integral role in the progression of several diseases including hypertension, heart failure, and renal disease. In this paper, the role of statins in the blockade of different components of this pathway and the underlying mechanisms are reviewed and new therapeutic possibilities of statins are suggested.

Statin withdrawal beyond acute phase affected outcome of thrombolytic stroke patients: an observational retrospective study

Statin withdrawal is associated with deleterious outcome on stroke patients. Whether risk changes over time, depends on concomitant treatment of intravenous thrombolysis, or both remains to be clarified. We assessed the influence of statin withdrawal within 3 weeks while initiated in acute phase (72 hours) among patients receiving intravenous thrombolysis.This was a monocentered retrospective observational study enrolling intravenous thrombolytic stroke patients from June 2009 to May 2014. Consecutive patients were distinguished into 3 groups according to the initiation and withdrawal of statin: the reference group (not received statin in 72 hours after stroke onset); the continued group (initiated statin therapy in 72 hours and continued for at least 3 weeks); the withdrawal group (initiated statin in 72 hours and discontinued within 3 weeks). All reasons for cessation were recorded. The effects of statin withdrawal on short-, mid-, and long-term outcomes were evaluated as neurologic improvement (NIH Stroke Scale [NIHSS] score improvement ≥4 from baseline or later NIHSS = 0), death or poor outcome (modified Rankin Scale [mRS] ≥4), and favorable outcome (mRS ≤2). We further evaluate statin withdrawal effects in cardioembolic stroke patients for these outcomes.Among 443 IVT patients enrolled, 367 were included in the final study population. There were 88, 188, and 91 patients in the reference, continued, and withdrawal groups, respectively. Multivariable logistic regression showed that statin withdrawal compared with the reference was related to a lower possibility of long-term favorable outcome (OR = 0.45, 95% CI [0.22, 0.90], P = 0.024). Compared with the continued group, the adjusted OR of statin withdrawal was 0.40 (95% CI [0.22, 0.72], P = 0.002) and 2.52 (95% CI [1.34, 4.75], P = 0.004) for long-term favorable and poor/death outcomes, respectively. Also, results were similar for cardioembolic stroke patients (OR = 0.35, 95% CI [0.14, 0.89], P = 0.027 of favorable outcome and OR = 3.62, 95% CI [1.37, 9.62], P = 0.010 of poor/death outcome).In a real-world setting, for stroke patients receiving intravenous thrombolysis, statin withdrawal within 3 weeks initiating in 72 hours may have a harmful effect on the long-term neurologic outcome, even in cardioembolic stroke patients.

Decreased tissue levels of cyclophilin A, a cyclosporine a target and phospho-ERK1/2 in simvastatin patients with abdominal aortic aneurysm

BACKGROUND

Cyclophilin A (CyPA), a cyclosporine A-binding protein, influences abdominal aortic aneurysm (AAA) formation and the ERK1/2 signalling pathway in animal and in vitro studies. Statins decrease CyPA in smooth muscle cells although their influence on CyPA in human AAA is unknown.

MATERIAL AND METHODS

The study was performed on AAA wall-tissue samples obtained from 30 simvastatin-treated and 15 non-statin patients (2:1 case to control). The patients were matched by age, sex and AAA diameter. We investigated the gene expression of CyPA, its receptor extracellular matrix metalloproteinase inducer (EMMPRIN) by real-time RT-PCR. CyPA and EMMPRIN protein level and phosphorylated extracellular signal-regulated kinases 1 and 2 (ERK1/2) were measured by Western blot.

RESULTS

The AAA wall tissue from simvastatin-treated patients had significantly lower CyPA gene expression and protein levels (P = 0.0018, P = 0.0083, respectively). Furthermore, phosphorylation of ERK1 and ERK2 was markedly suppressed in the simvastatin group (P = 0.0002, P = 0.0027, respectively). However, simvastatin did not influence EMMPRIN gene and protein expression.

CONCLUSION

Simvastatin-treated patients with AAA exert lower CyPA messenger RNA (mRNA), as well as CyPA intracellular protein levels and a decreased amount of phospho-ERK1/2. Thus, the interference with signalling pathways leading to CyPA formation and ERK1/2 activation reveals a new anti-inflammatory role of statins in AAA.

Influence of atorvastatin on angiotensin I metabolism in resting and TNF-α -activated rat vascular smooth muscle cells

INTRODUCTION

Vascular smooth muscle cells (VSMCs) are essential for maintaining vasculature homeostasis and function. By influence on its growth and activation both proinflammatory cytokines and peptides of the renin-angiotensin system (RAS) are potent regulators of VSMCs. Interestingly, angiotensin (Ang) II and Ang-(1-7) elicit opposite effects on VSMC activation, differentiation and proliferation. It has been suggested that statins, besides anti-inflammatory effects, may also modulate VSMC activation by their influence on the RAS.

METHODS

The effect of atorvastatin on Ang I metabolism in a culture of explanted rat VSMCs was examined by liquid chromatography-mass spectrometry (LC-MS); expression of mRNA of the main RAS enzymes in VSMC was assessed by real-time polymerase chain reaction (PCR).

RESULTS

In VSMC culture Ang-(1-7) was identified as a major product of Ang I metabolism. In this setting, TNF-α (1 ng/ml) caused a decrease in the conversion of Ang I to Ang-(1-7). This effect was accompanied by a decrease of mRNA expression of neutral endopeptidase (NEP) and angiotensin converting enzyme 2 (ACE2) and increase of mRNA of ACE. Interestingly, atorvastatin (3 μM) attenuated the effects of TNF-α on Ang-(1-7) production as well as reversed the influence of TNF-α on ACE and ACE2 expression.

CONCLUSIONS

Enhancement by atorvastatin of the ACE2/Ang-(1-7) axis in VSMCs could represent a new and beneficial mechanism on cardiovascular action of this widely used drug.

A low-dose atorvastatin and losartan combination directly improves aortic ring relaxation and diminishes ischaemic-reperfusion injury in isolated rat hearts

Background

The cardiovascular pleiotropic effects of statins and angiotensin receptor blockers (ARBs) could be of interest for innovative preventive approaches. We aimed to investigate whether low-dose atorvastatin and losartan, separately not possessing protective cardiovascular pleiotropic effects, express them when combined.

Material/Methods

Forty-five adult male Wistar rats were anaesthetized and their thoracic aortas and hearts were isolated. Relaxation of aortic rings, coronary flow rate and the extent of myocardial ischaemic-reperfusion injury were measured. Different concentrations (0.01, 0.1, 1.0 μM) of atorvastatin and losartan added to a perfusion medium were first tested. The separate drugs, which were ineffective, were then combined at the same concentrations and the concentration was tested in the same model.

Results

Low concentrations of atorvastatin or losartan (0.1 and 1 μM, respectively) produced no effects in isolated aorta. However, surprisingly, when these drug concentrations were combined, a significantly improved endothelium-dependent relaxation of the thoracic aorta was observed. Similarly, when combining individually ineffective concentrations of atorvastatin or losartan (0.01 and 0.1 μM, respectively), significantly increased coronary flow and a decreased extent of myocardial injury were observed. By using a nitric oxide-synthase inhibitor, we demonstrated that the vasodilatory effects obtained were nitric oxide-dependent. The degree of effectiveness by the combination was comparable to that obtained by 10-fold (atorvastatin) or 100-fold (losartan) higher concentrations of the separate drugs.

Conclusions

Our results revealed that remarkable additive/synergistic effects exist between low-doses of a statin (atorvastatin) and an ARB (losartan), resulting in important cardiovascular protection. This new concept could be valuable in cardiovascular prevention.

Treatment With Low-dose Atorvastatin, Losartan, and Their Combination Increases Expression of Vasoactive-Related Genes in Rat Aortas

Recently it has been shown that statins and angiotensin receptor blockers (ARBs) at low doses express beneficial pleiotropic vascular effects. We aimed to explore whether these drugs at low doses induce the expression of vasoactive-related genes. Sixty adult Wistar rats were treated with low-dose atorvastatin (2 mg/kg), low-dose losartan (5 mg/kg), their combination or saline daily for 4, 6, or 8 weeks. Expression of the vasoactive-related genes endothelin receptor type A ( EDNRA), endothelial nitric oxide synthase 3 ( NOS3), inducible nitric oxide synthase 2 ( NOS2), and angiotensin II receptor type 1 ( AGTRL1a) was measured in isolated thoracic aortas. Expression of EDNRA gradually decreased, the lowest values being obtained after 8 weeks (low-dose atorvastatin, losartan [1.6- and 1-7-fold vs controls, respectively; both P < .05], and the combination [2.3-fold vs control, P < .001]). The highest values of NOS3 were obtained after 6 weeks (low-dose atorvastatin, losartan, and their combination, 3.1-fold, P < .01; 3.4-fold, P < .001; and 3.6-fold, P < .001 vs controls, respectively) and then declined after 8 weeks. The combination was more effective in inducing total NOS3 expression when compared to the separate drugs (1.4-fold; P < .05). Importantly, expression of NOS3 was associated with increased plasma NO levels and positively correlated with thoracic aorta relaxation. No changes in expression of NOS2 and AGTRL1a were observed. We showed that low-dose atorvastatin or losartan and especially their combination increases the expression of NOS3 and decreases the expression of EDNRA. These findings are valuable in explaining the effectiveness of the “low-dose pharmacological approach” for improvement in arterial function.

Simvastatin reduces pressor response to centrally administered angiotensin II

BACKGROUND

Angiotensin II (Ang II) plays a pivotal role in regulation of the circulatory system. Activation of angiotensin type 1 (AT1) receptors in several brain regions leads to an increase in blood pressure. Accumulating data suggest that statins affect the peripheral action of Ang II; however, their central effects are poorly recognized. The study was aimed to determine whether simvastatin interferes with the brain angiotensin system in rats.

METHODS

Twelve-week-old, Sprague-Dawley rats were divided into two groups. Untreated group was maintained on tap water, whereas simvastatin group received water containing simvastatin for the following 12 weeks. Later, both groups were subjected to experiments in which mean arterial blood pressure (MABP) and heart rate (HR) were recorded during baseline conditions and after intracerebroventricular (ICV) infusion of either saline, Ang II, or losartan.

RESULTS

ICV infusion of Ang II elicited a significant increase in MABP in both groups. However, the pressor response in the simvastatin group was significantly smaller than that in the untreated group. There was no significant change in MABP after ICV infusion of saline or losartan. ICV infusion of Ang II elicited a significant increase in HR in the untreated group but not in the simvastatin group. There was no significant change in HR after ICV infusion of saline or losartan.

CONCLUSIONS

The results show that simvastatin reduces the pressor response to ICV-infused Ang II in rats. This implies that statins may affect the central regulation of the circulatory system, especially when the brain angiotensin system is stimulated.

Targeting the airway smooth muscle for asthma treatment

Asthma is a complex respiratory disease whose incidence has increased worldwide in the last decade. Currently there is no cure for asthma. Although bronchodilator and anti-inflammatory medications are effective medicines in some asthmatic patients, it is clear that an unmet therapeutic need persists for a subpopulation of individuals with severe asthma. This chronic lung disease is characterized by airflow limitation, lung inflammation, and remodeling that includes increased airway smooth muscle (ASM) mass. In addition to its contractile properties, the ASM also contributes to the inflammatory process by producing active mediators, which modify the extracellular matrix composition and interact with inflammatory cells. These undesirable functions make interventions aimed at reducing ASM abundance an attractive strategy for novel asthma therapies. The following three mechanisms could limit the accumulation of smooth muscle: decreased cell proliferation, augmented cell apoptosis, and reduced cell migration into the smooth muscle layer. Inhibitors of the mevalonate pathway or statins hold promise for asthma treatment, because they exhibit anti-inflammatory, antimigratory, and antiproliferative effects in preclinical and clinical studies, and they can target the smooth muscle. This review will discuss current knowledge of ASM biology and identify gaps in the field to stimulate future investigations of the cellular mechanisms that control ASM overabundance in asthma. Targeting ASM has the potential to be an innovative venue of treatment for patients with asthma.

Rosuvastatin attenuates Ang II--mediated cardiomyocyte hypertrophy via inhibition of LOX-1

3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors, also known as statins, have been shown to reduce cardiac remodeling. Angiotensin II (Ang II) type 1 receptor (AT1R) and oxidized low-density lipoprotein (ox-LDL) via its lectin-like ox-LDL receptor (LOX-1) are major stimuli for cardiomyocyte growth. We postulated that rosuvastatin, a potent HMG-CoA reductase inhibitor, may reduce Ang II-mediated cardiomyocyte growth via AT1R and LOX-1 inhibition. HL-1 adult mouse cardiomyocytes were incubated overnight in serum-free medium, and then treated with rosuvastatin, the AT1R inhibitor losartan or anti-LOX-1 antibody for 3 hours. The cells were then stimulated with Ang II. We measured cardiomyocyte growth, and associated intracellular redox signals using reverse transcription- polymerase chain reaction (RT-PCR) and real-time quantitative PCR. Losartan and anti-LOX-1 antibody markedly attenuated Ang II-mediated oxidant stress, and the expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (p40(phox) and gp91(phox) subunits) and nuclear factor-kappaB (NF-kappaB). Rosuvastatin attenuated the Ang II-mediated upregulation of both subunits of NAPDH oxidase as well as NF-kappaB. Rosuvastatin also reduced Ang II-mediated upregulation of AT1R and LOX-1. In other experiments, LOX-1 was upregulated in cardiomyocytes by transfection with pCI-neo/LOX-1, which also enhanced the expression AT1R messenger RNA (mRNA), and rosuvastatin pretreatment reduced the expression of both LOX-1 and AT1R in this system. Thus, rosuvastatin attenuates Ang II-mediated cardiomyocyte growth by inhibiting LOX-1 and AT1R expression and suppressing the heightened intracellular redox state.