Beneficial effect of rosuvastatin on cardiac dysfunction is associated with alterations in calcium-regulatory proteins

Cardiac-specific deletion of FDPS induces cardiac remodeling and dysfunction by enhancing the activity of small GTP-binding proteins

The mevalonate pathway is essential for cholesterol biosynthesis. Previous studies have suggested that the key enzyme in this pathway, farnesyl diphosphate synthase (FDPS), regulates the cardiovascular system. We used human samples and mice that were deficient in cardiac FDPS (c-Fdps^-/- mice) to investigate the role of FDPS in cardiac homeostasis. Cardiac function was assessed using echocardiography. Left ventricles were examined and tested for histological and molecular markers of cardiac remodeling. Our results showed that FDPS levels were downregulated in samples from patients with cardiomyopathy. Furthermore, c-Fdps^-/- mice exhibited cardiac remodeling and dysfunction. This dysfunction was associated with abnormal activation of Ras and Rheb, which may be due to the accumulation of geranyl pyrophosphate. Activation of Ras and Rheb stimulated downstream mTOR and ERK pathways. Moreover, administration of farnesyltransferase inhibitors attenuated cardiac remodeling and dysfunction in c-Fdps^-/- mice. These results indicate that FDPS plays an important role in cardiac homeostasis. Deletion of FDPS stimulates the downstream mTOR and ERK signaling pathways, resulting in cardiac remodeling and dysfunction. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Key Enzymes for the Mevalonate Pathway in the Cardiovascular System

ABSTRACT

Isoprenylation is an important post-transcriptional modification of small GTPases required for their activation and function. Isoprenoids, including farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate, are indispensable for isoprenylation by serving as donors of a prenyl moiety to small G proteins. In the human body, isoprenoids are mainly generated by the mevalonate pathway (also known as the cholesterol-synthesis pathway). The hydroxymethylglutaryl coenzyme A reductase catalyzes the first rate-limiting steps of the mevalonate pathway, and its inhibitor (statins) are widely used as lipid-lowering agents. In addition, the FPP synthase is also of critical importance for the regulation of the isoprenoids production, for which the inhibitor is mainly used in the treatment of osteoporosis. Synthetic FPP can be further used to generate geranylgeranyl pyrophosphate and cholesterol. Recent studies suggest a role for isoprenoids in the genesis and development of cardiovascular disorders, such as pathological cardiac hypertrophy, fibrosis, endothelial dysfunction, and fibrotic responses of smooth-muscle cells. Furthermore, statins and FPP synthase inhibitors have also been applied for the management of heart failure and other cardiovascular diseases rather than their clinical use for hyperlipidemia or bone diseases. In this review, we focus on the function of several critical enzymes, including hydroxymethylglutaryl coenzyme A reductase, FPP synthase, farnesyltransferase, and geranylgeranyltransferase in the mevalonate pathway which are involved in regulating the generation of isoprenoids and isoprenylation of small GTPases, and their pathophysiological role in the cardiovascular system. Moreover, we summarize recent research into applications of statins and the FPP synthase inhibitors to treat cardiovascular diseases, rather than for their traditional indications respectively.

Activation of Toll-like receptor 7 provides cardioprotection in septic cardiomyopathy-induced systolic dysfunction

BACKGROUND

As a pattern recognition receptor, Toll-like receptor 7 (TLR7) widely presented in the endosomal membrane of various cells. However, the precise role and mechanism of TLR7 in septic cardiomyopathy remain unknown. This study aims to determine the role of TLR7 in cardiac dysfunction during sepsis and explore the mechanism of TLR7 in septic cardiomyopathy.

METHODS

We generated a mouse model of septic cardiomyopathy by challenging with lipopolysaccharide (LPS). TLR7-knockout (TLR7-/- ), wild-type (WT) mice, cardiac-specific TLR7-transgenic (cTG-TLR7) overexpression, and littermates WT (LWT) mice were subjected to septic model. Additionally, to verify the role and mechanism of TLR7 in vitro, we transfected neonatal rat ventricular myocytes (NRVMs) with Ad-TLR7 and TLR7 siRNA before LPS administration. The effects of TLR7 were assessed by Ca2+ imaging, western blotting, immunostaining, and quantitative real-time polymerase chain reaction (qPCR).

RESULTS

We found that TLR7 knockout markedly exacerbated sepsis-induced systolic dysfunction. Moreover, cardiomyocytes isolated from TLR7-/- mice displayed weaker Ca2+ handling than that in WT mice in response to LPS. Conversely, TLR7 overexpression alleviated LPS-induced systolic dysfunction, and loxoribine (TLR7-specific agonist) improved LPS-induced cardiac dysfunction. Mechanistically, these optimized effects were associated with enhanced the adenosine (cAMP)-protein kinase A (PKA) pathway, which upregulated phosphorylate-phospholamban (p-PLN) (Ser16) and promoted sarco/endoplasmic reticulum Ca2+ ATPase (Serca) and Ryanodine Receptor 2 (RyR2) expression in the sarcoplasmic reticulum (SR), and ultimately restored Ca2+ handling in response to sepsis. While improved Ca2+ handling was abrogated after H89 (a specific PKA inhibitor) pretreatment in cardiomyocytes isolated from cTG-TLR7 mice. Consistently, TLR7 overexpression improved LPS-induced Ca2+ -handling decrement in NRVMs. Nevertheless, TLR7 knockdown showed a deteriorative phenotype.

CONCLUSIONS

Our data demonstrated that activation of TLR7 protected against sepsis-induced cardiac dysfunction through promoting cAMP-PKA-PLN pathway, and we revealed that TLR7 might be a novel therapeutic target to block the septic cardiomyopathy and support systolic function during sepsis.

Inhibition of mevalonate pathway prevents ischemia-induced cardiac dysfunction in rats via RhoA-independent signaling pathway

AIM

We previously demonstrated that anoxia-mediated Ca²⁺ handling dysfunction could be ameliorated through inhibition of mevalonate pathway via RhoA- and Ras-related mechanisms in H9c2 cells. In this study, we further explored whether inhibition of mevalonate pathway is associated with cardiac remodeling and dysfunction in ischemic cardiomyopathy, and discussed the possible role of Ras, Rac and RhoA in cardiac dysfunction.

METHODS

We investigated the role of mevalonate pathway in cardiac remodeling and cardiomyocyte Ca²⁺ handling proteins expression in a rat model of cardiac dysfunction due to myocardial infarction (MI). After MI, adult male Sprague-Dawley rats were treated with drugs that antagonize key components in mevalonate pathway, including 3-hydroxy-3-methylglutaryl-CoA reductase, farnesyl pyrophosphate synthase, and Rho-kinase for 10 weeks. The protein expression of ryanodine receptor 2 (RyR2), sarcoplasmic reticulum Ca²⁺ ATPase (SERCA) 2a, phospholamban (PLB), phospho-PLB at serine-16 (PSer16-PLB), FKBP12.6, and RhoA as well as RyR2 and FKBP12.6 mRNA levels was evaluated.

RESULTS

Rosuvastatin and alendronate treatment prevented myocardial remodeling, improved cardiac function and reduced infarct size. Furthermore, rosuvastatin and alendronate promoted an increase in the protein expression of SERCA2a and PSer16-PLB/PLB ratio as well as partially restored the RyR2 and FKBP12.6 gene and protein expression. Fasudil failed to exert these beneficial effects.

CONCLUSIONS

These findings indicate that mevalonate pathway inhibition by rosuvastatin and alendronate prevents cardiac remodeling and dysfunction possibly through RhoA-independent mechanisms.

Ticagrelor and Rosuvastatin Have Additive Cardioprotective Effects via Adenosine

BACKGROUND

Ticagrelor inhibits the equilibrative-nucleoside-transporter-1 and thereby, adenosine cell re-uptake. Ticagrelor limits infarct size (IS) in non-diabetic rats and the effect is adenosine-dependent. Statins, via ecto-5'-nucleotidase activation, also increase adenosine levels and limit IS.

HYPOTHESIS

Ticagrelor and rosuvastatin have additive effects on myocardial adenosine levels, and therefore, on IS and post-reperfusion activation of the NLRP3-inflammasome.

METHODS

Diabetic ZDF rats received via oral gavage; water (control), ticagrelor (150 mg/kg/d), prasugrel (7.5 mg/kg/d), rosuvastatin (5 mg/kg/d), ticagrelor + rosuvastatin and prasugrel + rosuvastatin for 3d. On day 4, rats underwent 30 min coronary artery occlusion and 24 h of reperfusion. Two additional groups received, ticagrelor + rosuvastatin or water in combination with CGS15943 (CGS, an adenosine receptor antagonist, 10 mg/kg i.p. 1 h before ischemia).

RESULTS

Both ticagrelor and rosuvastatin increased myocardial adenosine levels with an additive effect of the combination whereas prasugrel had no effect. Similarly, both ticagrelor and rosuvastatin significantly reduced IS with an additive effect of the combination whereas prasugrel had no effect. The effect on IS was adenosine dependent as CGS15943 reversed the effect of ticagrelor + rosuvastatin. The ischemia-reperfusion injury increased myocardial mRNA levels of NLRP3, ASC, IL-1β and IL-6. Ticagrelor and rosuvastatin, but not prasugrel, significantly decreased these pro-inflammatory mediators with a trend to an additive effect of the combination. The combination also increased the levels of anti-inflammatory 15-epilipoxin A₄.

CONCLUSIONS

Ticagrelor and rosuvastatin when given in combination have an additive effect on local myocardial adenosine levels in the setting of ischemia reperfusion. This translates into an additive cardioprotective effect mediated by adenosine-induced effects including downregulation of pro- but upregulation of anti-inflammatory mediators.

Review of novel therapeutic targets for improving heart failure treatment based on experimental and clinical studies

Heart failure (HF) is a major public health priority due to its epidemiological transition and the world's aging population. HF is typified by continuous loss of contractile function with reduced, normal, or preserved ejection fraction, elevated vascular resistance, fluid and autonomic imbalance, and ventricular dilatation. Despite considerable advances in the treatment of HF over the past few decades, mortality remains substantial. Pharmacological treatments including β-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and aldosterone antagonists have been proven to prolong the survival of patients with HF. However, there are still instances where patients remain symptomatic, despite optimal use of existing therapeutic agents. This understanding that patients with chronic HF progress into advanced stages despite receiving optimal treatment has increased the quest for alternatives, exploring the roles of additional pathways that contribute to the development and progression of HF. Several pharmacological targets associated with pathogenesis of HF have been identified and novel therapies have emerged. In this work, we review recent evidence from proposed mechanisms to the outcomes of experimental and clinical studies of the novel pharmacological agents that have emerged for the treatment of HF.

Inhibition of the mevalonate pathway ameliorates anoxia-induced down-regulation of FKBP12.6 and intracellular calcium handling dysfunction in H9c2 cells

Statins have beneficial pleiotropic effects beyond lipid lowering on the cardiovascular system. These cardio-protective effects are mediated through inhibition of the intracellular mevalonate pathway, by decreasing isoprenoid intermediate synthesis and the subsequent post-translational modification of small GTPases, such as Ras, Rho, and Rac. Impaired intracellular calcium handling is considered an important pathophysiologic mechanism responsible for cardiac dysfunction. Our study aimed at investigating the influence of mevalonate pathway, including its downstream small GTPases (Ras, RhoA, and Rac1) on anoxia-mediated alterations of calcium handling in H9c2 cardiomyocytes. Cultured H9c2 cardiomyocytes were exposed to acute anoxia after pretreatment with different drugs that specifically antagonize five key components in the mevalonate pathway, including 3-hydroxy-3-methylglutaryl-CoA reductase, farnesyl pyrophosphate synthase, Rho-kinase, Rac1 and Ras farnesyltransferase. Thereafter, we evaluated the effects of the mevalonate pathway on anoxia-induced cell death, expression of the sarcoplasmic reticulum calcium release channel (ryanodine receptor 2) and its regulator FK506-binding protein 12.6, as well as functional calcium release from intracellular calcium stores. Our experiments confirmed the role of prenylated proteins in regulating cardiomyocyte dysfunction, especially via RhoA- and Ras-related signaling pathways. Furthermore, our data demonstrated that inhibition of the mevalonate pathway could ameliorate anoxia-mediated calcium handling dysfunction with the up-regulated expression of FK506-binding protein 12.6 and consequently provided evidence for FK506-binding protein 12.6 as a "stabilizer" of ryanodine receptor 2.

N-acylhydrazone derivative ameliorates monocrotaline-induced pulmonary hypertension through the modulation of adenosine AA2R activity

BACKGROUND

Pulmonary arterial hypertension (PAH) is a disease that results in right ventricular (RV) dysfunction. While pulmonary vascular disease is the primary pathological focus, RV hypertrophy and RV dysfunction are the major determinants of prognosis in PAH. The aim of this study was to investigate the effects of (E)-N'-(3,4-dimethoxybenzylidene)-4-methoxybenzohydrazide (LASSBio-1386), an N-acylhydrazone derivative, on the lung vasculature and RV dysfunction induced by experimental PAH.

METHODS

Male Wistar rats were injected with a single dose (60mg/kg, i.p.) of monocrotaline (MCT) and given LASSBio-1386 (50mg/kg, p.o.) or vehicle for 14 days. The hemodynamic, exercise capacity (EC), endothelial nitric oxide synthase (eNOS), adenosine A2A receptor (A2AR), sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA2a), phospholamban (PLB) expression, Ca(2+)-ATPase activity and vascular activity of LASSBio-1386 were evaluated.

RESULTS AND CONCLUSIONS

The RV systolic pressure was elevated in the PAH model and reduced from 49.6 ± 5.0 mm Hg (MCT group) to 27.2 ± 2.1 mm Hg (MCT+LASSBio-1386 group; P<0.05). MCT administration also impaired the EC, increased the RV and pulmonary arteriole size, and promoted endothelial dysfunction of the pulmonary artery rings. In the PAH group, the eNOS, A2AR, SERCA2a, and PLB levels were changed compared with the control; in addition, the Ca(2+)-ATPase activity was reduced. These alterations were related with MCT-injected rats, and LASSBio-1386 had favorable effects that prevented the development of PAH. LASSBio-1386 is effective at preventing endothelial and RV dysfunction in PAH, a finding that may have important implications for ongoing clinical evaluation of A2AR agonists for the treatment of PAH.

Optimization of the cardiovascular therapeutic properties of mesenchymal stromal/stem cells-taking the next step

Despite current treatment options, cardiac failure is associated with significant morbidity and mortality highlighting a compelling clinical need for novel therapeutic approaches. Based on promising pre-clinical data, stem cell therapy has been suggested as a possible therapeutic strategy. Of the candidate cell types evaluated, mesenchymal stromal/stem cells (MSCs) have been widely evaluated due to their ease of isolation and ex vivo expansion, potential allogeneic utility and capacity to promote neo-angiogenesis and endogenous cardiac repair. However, the clinical application of MSCs for mainstream cardiovascular use is currently hindered by several important limitations, including suboptimal retention and engraftment and restricted capacity for bona fide cardiomyocyte regeneration. Consequently, this has prompted intense efforts to advance the therapeutic properties of MSCs for cardiovascular disease. In this review, we consider the scope of benefit from traditional plastic adherence-isolated MSCs and the lessons learned from their conventional use in preclinical and clinical studies. Focus is then given to the evolving strategies aimed at optimizing MSC therapy, including discussion of cell-targeted techniques that encompass the preparation, pre-conditioning and manipulation of these cells ex vivo, methods to improve their delivery to the heart and innovative substrate-directed strategies to support their interaction with the host myocardium.

Long-term administration of rosuvastatin prevents contractile and electrical remodelling of diabetic rat heart

In recent years, many findings have been presented about the potential benefit of statin therapy on diabetes-induced cardiovascular complications. Cardioprotective effects of statins were suggested to be mediated at least in part through inhibition of small GTPases, particularly those of the Rho family. The present study was designed to examine whether rosuvastatin can improve electrical remodeling and contractile dysfunction in type 1 diabetic rat heart via modulation of RhoA pathway. Type 1 diabetes was induced by single dose injection of STZ (50 mg/kg). One week after injection rosuvastatin (10 mg/kg/day) and sham treatment was given for 5 weeks in the diabetic rats, as well as in control groups. Shortening and Ca²⁺ transients were recorded in myocytes loaded with Fura2-AM. Membrane currents and Ca²⁺ transients were measured synchronously via whole-cell patch clamping. In untreated diabetic rats, relaxation of shortening and decay of the matched Ca²⁺ transients were prolonged. Fractional shortening and Ca²⁺ transients were also decreased. Rosuvastatin treatment reversed those changes. I(CaL) density did not change in either group but rosuvastatin recovered the loss of sarcoplasmic reticulum Ca²⁺ and Na⁺/Ca²⁺ exchange as evidenced from amplitude and decay of caffeine-induced Ca²⁺ transients, peak INCX and calculated sarcoplasmic reticulum Ca²⁺ content. Diabetes-induced attenuation of I(to) and I(sus) was also reversed, whilst I(K1) was unchanged in diabetes and unaffected by treatment. Rosuvastatin prevented the diabetes-induced increase in RhoA expression. Plasma cholesterol and triglyceride levels were higher in diabetic rats, but rosuvastatin reduced only the latter. In conclusion, HMG-CoA reductase inhibitor rosuvastatin can prevent diabetes-induced electrical and functional remodeling of heart due to inhibition of RhoA signalling rather than reduction of cholesterol level.

Statins as anti-inflammatory agents in atherogenesis: molecular mechanisms and lessons from the recent clinical trials

Ample evidence exists in support of the potent anti-inflammatory properties of statins. In cell studies and animal models statins exert beneficial cardiovascular effects. By inhibiting intracellular isoprenoids formation, statins suppress vascular and myocardial inflammation, favorably modulate vascular and myocardial redox state and improve nitric oxide bioavailability. Randomized clinical trials have demonstrated that further to their lipid lowering effects, statins are useful in the primary and secondary prevention of coronary heart disease (CHD) due to their anti-inflammatory potential. The landmark JUPITER trial suggested that in subjects without CHD, suppression of low-grade inflammation by statins improves clinical outcome. However, recent trials have failed to document any clinical benefit with statins in high risk groups, such in heart failure or chronic kidney disease patients. In this review, we aim to summarize the existing evidence on statins as an anti-inflammatory agent in atherogenesis. We describe the molecular mechanisms responsible for the anti-inflammatory effects of statins, as well as clinical data on the non lipid-lowering, anti-inflammatory effects of statins on cardiovascular outcomes. Lastly, the controversy of the recent large randomized clinical trials and the issue of statin withdrawal are also discussed.

Dipeptidyl peptidase IV inhibition improves cardiorenal function in overpacing-induced heart failure

AIMS

Recent studies indicate that brain natriuretic peptide (BNP(1-32)) may be truncated into BNP(3-32) by dipeptidyl peptidase IV (DPP4) and that BNP(3-32) has reduced biological activities compared with BNP(1-32). We investigated if DPP4 contributes to the cardiorenal alterations and to the attenuated response to BNP seen in heart failure.

METHODS AND RESULTS

Haemodynamic and renal assessment was performed in 12 pigs at baseline, 4 weeks after pacing-induced heart failure, and during BNP infusion. They were randomized to either placebo or treatment with a DPP4 inhibitor, sitagliptin. After 4 weeks of pacing, heart rate was reduced compared with baseline in the sitagliptin group (60 ± 2 vs. 95 ± 16 b.p.m., P < 0.01), and an increase in stroke volume was observed in the sitagliptin group compared with placebo (+24 ± 6% vs. -17 ± 7%, P < 0.01). Glomerular filtration rate declined at week 4 compared with baseline in the placebo group (1.3 ± 0.4 vs. 2.3 ± 0.3 mL/kg/min, P < 0.01) but remained preserved in the sitagliptin group [1.8 ± 0.2 vs. 2.0 ± 0.3 mL/kg/min, P = NS (non-significant)]. In the sitagliptin group, BNP infusion improved end-systolic elastance (68 ± 5 vs. 31 ± 4 mmHg/kg/mL, P < 0.05), ventricular-arterial coupling, and mechanical efficiency. Compared with controls (n = 6), myocardial gene expression of BNP, interleukin-6, Na(+)-Ca(2+) exchanger, and calmodulin was up-regulated in the placebo group, but not in the sitagliptin group.

CONCLUSION

In pacing-induced heart failure, DPP4 inhibition preserves the glomerular filtration rate, modulates stroke volume and heart rate, and potentiates the positive inotropic effect of exogenous BNP at no energy expense.

WITHDRAWN: Simvastatin prevents decreased SERCA2a activity in non-ischemic heart failure in rabbits via inhibition of β-adrenergic signaling

The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/10.1016/j.biomag.2010.09.003. The duplicate article has therefore been withdrawn.