Pitavastatin, a 3-Hydroxy-3-methylglutaryl-coenzyme A Reductase Inhibitor, Blocks Vascular Smooth Muscle Cell Populated-Collagen Lattice Contraction

RAAS inhibitors directly reduce diabetes-induced renal fibrosis via growth factor inhibition

KEY POINTS

Increased activation of the renin-angiotensin-aldosterone system (RAAS) and elevated growth factor production are of crucial importance in the development of renal fibrosis leading to diabetic kidney disease. The aim of this study was to provide evidence for the antifibrotic potential of RAAS inhibitor (RAASi) treatment and to explore the exact mechanism of this protective effect. We found that RAASi ameliorate diabetes-induced renal interstitial fibrosis and decrease profibrotic growth factor production. RAASi prevents fibrosis by acting directly on proximal tubular cells, and inhibits hyperglycaemia-induced growth factor production and thereby fibroblast activation. These results suggest a novel therapeutic indication and potential of RAASi in the treatment of renal fibrosis.

ABSTRACT

In diabetic kidney disease (DKD) increased activation of renin-angiotensin-aldosterone system (RAAS) contributes to renal fibrosis. Although RAAS inhibitors (RAASi) are the gold standard therapy in DKD, the mechanism of their antifibrotic effect is not yet clarified. Here we tested the antifibrotic and renoprotective action of RAASi in a rat model of streptozotocin-induced DKD. In vitro studies on proximal tubular cells and renal fibroblasts were also performed to further clarify the signal transduction pathways that are directly altered by hyperglycaemia. After 5 weeks of diabetes, male Wistar rats were treated for two more weeks per os with the RAASi ramipril, losartan, spironolactone or eplerenone. Proximal tubular cells were cultured in normal or high glucose (HG) medium and treated with RAASi. Platelet-derived growth factor (PDGF) or connective tissue growth factor (CTGF/CCN2)-induced renal fibroblasts were also treated with various RAASi. In diabetic rats, reduced renal function and interstitial fibrosis were ameliorated and elevated renal profibrotic factors (TGFβ1, PDGF, CTGF/CCN2, MMP2, TIMP1) and alpha-smooth muscle actin (αSMA) levels were decreased by RAASi. HG increased growth factor production of HK-2 cells, which in turn induced activation and αSMA production of fibroblasts. RAASi decreased tubular PDGF and CTGF expression and reduced production of extracellular matrix (ECM) components in fibroblasts. In proximal tubular cells, hyperglycaemia-induced growth factor production increased renal fibroblast transformation, contributing to the development of fibrosis. RAASi, even in non-antihypertensive doses, decreased the production of profibrotic factors and directly prevented fibroblast activation. All these findings suggest a novel therapeutic role for RAASi in the treatment of renal fibrosis.

Repurposing simvastatin as a therapy for preterm labor: evidence from preclinical models

Preterm birth (PTB), the leading cause of neonatal morbidity and mortality, urgently requires novel therapeutic agents. Spontaneous PTB, resulting from preterm labor, is commonly caused by intrauterine infection/inflammation. Statins are well-established, cholesterol-lowering drugs that can reduce inflammation and inhibit vascular smooth muscle contraction. We show that simvastatin reduced the incidence of PTB in a validated intrauterine LPS-induced PTB mouse model, decreased uterine proinflammatory mRNA concentrations (IL-6, Cxcl1, and Ccl2), and reduced serum IL-6 concentration. In human myometrial cells, simvastatin reduced proinflammatory mediator mRNA and protein expression (IL-6 and IL-8) and increased anti-inflammatory cytokine mRNA expression (IL-10 and IL-13). Critically, simvastatin inhibited myometrial cell contraction, basally and during inflammation, and reduced phosphorylated myosin light chain concentration. Supplementation with mevalonate and geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate, abolished these anticontractile effects, indicating that the Rho/Rho-associated protein kinase pathway is critically involved. Thus, simvastatin reduces PTB incidence in mice, inhibits myometrial contractions, and exhibits key anti-inflammatory effects, providing a rationale for investigation into the repurposing of statins to treat preterm labor in women.—Boyle, A. K., Rinaldi, S. F., Rossi, A. G., Saunders, P. T. K., Norman, J. E. Repurposing simvastatin as a therapy for preterm labor: evidence from preclinical models.

Cysteinyl cathepsins: multifunctional enzymes in cardiovascular disease

Until recently, the role of lysosomal cysteine protease cathepsins in intracellular protein degradation was believed to be mainly restricted to scavenging. However, recent studies have revealed nontraditional roles for cysteine protease cathepsins in the extracellular space during the development and progression of cardiovascular disease. Although the precise mechanisms are unknown, data from animal studies suggest that members of the cathepsin family, like other extracellular proteases, contribute to extracellular matrix protein remodeling and interstitial matrix degradation, as well as to cell signaling and cell apoptosis in heart disease. Inflammatory cytokines and hormones regulate the expression and secretion of cathepsins in cultured cardiovascular cells and macrophages. Serum levels of cathepsins L, S, and K and their endogenous inhibitor cystatin C may be useful predictive biomarkers in patients with coronary artery disease and cardiac disease. Furthermore, in vivo pharmacological intervention with a synthetic cathepsin inhibitor and cardiovascular drugs (including statins and angiotensin II type 1 receptor antagonists) has the potential for pharmacologic targeting of cathepsins in cardiovascular disease. This review focuses on cathepsin biology (structure, synthesis, processing, activation, secretion, activity regulation, and function) and the involvement of cysteinyl cathepsins in the pathogenesis of several heart and vessel diseases, especially with respect to their potential application as diagnostic and prognostic markers and drug targets to prevent inappropriate proteolysis in cardiovascular disease.

Are all statins the same? Focus on the efficacy and tolerability of pitavastatin

Pitavastatin is the newest member of the HMG-CoA reductase inhibitor family and is approved as adjunctive therapy to diet to reduce elevated levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, apolipoprotein (Apo) B, and triglycerides and to increase levels of high-density lipoprotein (HDL) cholesterol in adult patients with primary hyperlipidemia or mixed dyslipidemia. Pitavastatin undergoes minimal metabolism by cytochrome P450 (CYP) enzymes and, therefore, has a low propensity for drug-drug interactions with drugs metabolized by CYP enzymes or the CYP3A4 substrate grapefruit juice. In clinical trials, pitavastatin potently and consistently reduced serum levels of total, LDL, and non-HDL cholesterol, and triglycerides in patients with primary hypercholesterolemia where diet and other non-pharmacological measures were inadequate. Mean reductions from baseline in serum total and LDL cholesterol and triglyceride levels were 21-32%, 30-45%, and 10-30%, respectively. Moreover, a consistent trend towards increased HDL cholesterol levels of 3-10% was seen. Long-term extension studies show that the beneficial effects of pitavastatin are maintained for up to 2 years. Pitavastatin produces reductions from baseline in serum total and LDL cholesterol levels to a similar extent to those seen with the potent agent atorvastatin and to a greater extent than those seen with simvastatin or pravastatin. In the majority of other studies comparing pitavastatin and atorvastatin, no significant differences in the favorable effects on lipid parameters were seen, although pitavastatin was consistently associated with trends towards increased HDL cholesterol levels. Pitavastatin also produces beneficial effects on lipids in patients with type 2 diabetes mellitus and metabolic syndrome without deleterious effects on markers of glucose metabolism, such as fasting blood glucose levels or proportion of glycosylated hemoglobin. Pitavastatin appears to exert a number of beneficial effects on patients at risk of cardiovascular events independent of lipid lowering. In the JAPAN-ACS (Japan Assessment of Pitavastatin and Atorvastatin in Acute Coronary Syndrome) study, pitavastatin was non-inferior to atorvastatin at reducing plaque volume in patients with ACS undergoing percutaneous coronary intervention. Further beneficial effects, including favorable effects on the size and composition of atherosclerotic plaques, improvements in cardiovascular function, and improvements in markers of inflammation, oxidative stress, and renal function, have been demonstrated in a number of small studies. Pitavastatin is generally well tolerated in hyperlipidemic patients with or without type 2 diabetes, with the most common treatment-related adverse events being musculoskeletal or gastrointestinal in nature. Increases in plasma creatine kinase levels were seen in <5% of pitavastatin recipients and the incidence of myopathy or rhabdomyolysis was extremely low. In summary, pitavastatin, the latest addition to the statin family, produces potent and consistent beneficial effects on lipids, is well tolerated, and has a favorable pharmacokinetic profile. The combination of a potent decrease in total and LDL cholesterol levels and increase in HDL cholesterol levels suggest that pitavastatin may produce substantial cardiovascular protection.

Influence of pitavastatin on glucose tolerance in patients with type 2 diabetes mellitus

AIM

We previously reported that glycemic control deteriorated in patients receiving atorvastatin, which is useful for the treatment of hypercholesterolemia in patients with type 2 diabetes. Pitavastatin has a strong lipid-lowering effect, comparable to that of atorvastatin, but it is unknown whether pitavastatin has an adverse influence on glycemic control. The aim of this study was to examine. The effects of three different statins (pravastatin, atorvastatin, and pitavastatin) on blood glucose and HbA(1C) levels in diabetic patients.

METHODS

We retrospectively compared glycemic control between groups receiving atorvastatin (10 mg/day, group A, n=99), pravastatin (10 mg/day, group Pr, n=85), and pitavastatin (2 mg/day, group Pi, n=95) from the start of treatment until 3 months later. Patients were excluded if the dosage of their antidiabetic drugs was changed, if their drug therapy was altered within 3 months before starting statin therapy, or if events occurred that could affect glycemic control such as hospitalization.

RESULTS

The subjects available for analysis were 74 patients from group A, 71 patients from group Pr, and 74 patients from group Pi. Arbitrary blood glucose levels increased from 147+/-51 mg/dL (mean+/-SD) to 176+/-69 mg/dL in group A, but only changed minimally from 136+/-31 to 134+/-32 mg/dL in group Pr and from 155+/-53 to 154+/-51 mg/dL in group Pi. HbA(1C) increased from 7.0+/-1.1% to 7.4+/-1.2% in group A, while it was 6.9+/-0.9% versus 6.9+/-1.0% in group Pr, and 7.3+/-1.0% versus 7.2+/-1.0% in group Pi. There was no correlation between Delta LDL-C and Delta HbA(1C) (the change from baseline to 3 months) in any of the groups.

CONCLUSION

The glycemic parameters only increased significantly in group A, suggesting that pitava-statin and pravastatin did not have an adverse influence on glycemic control in type 2 diabetic patients.

A contraction assay system using established human bronchial smooth muscle cells

BACKGROUND

To further understand the mechanisms of airway obstruction in asthma, it is crucial to investigate contractile responses of human airway smooth muscle. An in vitro assay system employing collagen gels embedded with well-established bronchial smooth muscle cells of human origin was explored in the present study.

METHODS

Commercially available cultured human bronchial smooth muscle cells were embedded into a collagen gel. Well-known constrictors, histamine and methacholine, were added to the gel. The gel images were captured by an image analyzer, and contractile responses were evaluated.

RESULTS

Histamine and methacholine induced contraction of the gels in a dose-dependent manner. Pyrilamine, an H1 receptor antagonist, inhibited gel contraction in an agonist-specific manner.

CONCLUSION

Our contraction assay system, employing widely distributed cultured cells, was highly reproducible and precise. It may go a long way toward understanding mechanisms of asthmatic responses and evaluation of antiasthma drugs.

Comparison of gel contraction mediated by airway smooth muscle cells from patients with and without asthma

BACKGROUND

Exaggerated bronchial constriction is the most significant and life threatening response of patients with asthma to inhaled stimuli. However, few studies have investigated the contractility of airway smooth muscle (ASM) from these patients. The purpose of this study was to establish a method to measure contraction of ASM cells by embedding them into a collagen gel, and to compare the contraction between subjects with and without asthma.

METHODS

Gel contraction to histamine was examined in floating gels containing cultured ASM cells from subjects with and without asthma following overnight incubation while unattached (method 1) or attached (method 2) to casting plates. Smooth muscle myosin light chain kinase protein levels were also examined.

RESULTS

Collagen gels containing ASM cells reduced in size when stimulated with histamine in a concentration-dependent manner and reached a maximum at a mean (SE) of 15.7 (1.2) min. This gel contraction was decreased by inhibitors for phospholipase C (U73122), myosin light chain kinase (ML-7) and Rho kinase (Y27632). When comparing the two patient groups, the maximal decreased area of gels containing ASM cells from patients with asthma was 19 (2)% (n = 8) using method 1 and 22 (3)% (n = 6) using method 2, both of which were greater than that of cells from patients without asthma: 13 (2)% (n = 9, p = 0.05) and 10 (4)% (n = 5, p = 0.024), respectively. Smooth muscle myosin light chain kinase levels were not different between the two groups.

CONCLUSION

The increased contraction of asthmatic ASM cells may be responsible for exaggerated bronchial constriction in asthma.

Japan Assessment of Pitavastatin and Atorvastatin in Acute Coronary Syndrome (JAPAN-ACS) Rationale and Design

BACKGROUND

Many trials have shown that 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors reduce the incidence of cardiovascular events and mortality. One method of decreasing the incidence of cardiovascular events could be to reduce the progression of coronary atherosclerosis, and a recent study found that atorvastatin can cause coronary plaque to regress. To generalize this finding, using conventional HMG-CoA reductase inhibitors at many Japanese centers, randomized trials of pitavastatin and atorvastatin will be conducted with patients with acute coronary syndrome (ACS).

METHODS AND RESULTS

Patients with ACS who have undergone successful percutaneous coronary intervention under intravascular ultrasound guidance will be studied. They will be randomly allocated to pitavastatin or atorvastatin groups and followed up for 8-12 months. The primary endpoint will be the percent change in coronary plaque volume, and secondary endpoints will include absolute changes in coronary plaque volume, serum lipid levels and inflammatory markers. The safety profile will also be evaluated.

CONCLUSIONS

This study will examine the ability of HMG-CoA reductase inhibitors to regress coronary plaque in Japanese patients with ACS and the findings should help to improve the prognosis of such patients and clarify the involved mechanisms.