Autophagy-urea cycle pathway is essential for the statin-mediated nitric oxide bioavailability in endothelial cells

Atypical antipsychotics impair the lipid-lowering and pleiotropic effects of simvastatin via activation of the ADMA-NOX-ROS pathway

Patients with schizophrenia receiving atypical antipsychotics have an increased risk of metabolic syndrome; however, the efficacy of statins in mitigating cardiovascular risks in these patients remains unclear. This study examined the effects of typical and atypical antipsychotics on the lipid-lowering efficacy of statins in schizophrenia patients and investigated the underlying mechanisms of simvastatin action in hepatocytes and endothelial cells (ECs). A retrospective analysis revealed that statins were less effective in lowering LDL levels in patients on atypical antipsychotics. In vitro, olanzapine attenuated the beneficial effects of simvastatin in hepatocytes and ECs. Mechanistically, olanzapine downregulated dimethylarginine dimethylaminohydrolase 1 (DDAH1) and/or DDAH2, leading to elevated asymmetric dimethylarginine (ADMA) levels in both cell types. In hepatocytes, olanzapine suppressed low-density lipoprotein receptor (LDLR) expression and reduced LDL binding by activating the NOX-ROS pathway via PPARγ-PCSK9- and LXRα-IDOL-dependent signaling. Inhibition of the NOX-ROS pathway restored LDLR expression, LDL binding, and the lipid-lowering effects of simvastatin. In ECs, olanzapine impaired simvastatin-induced nitric oxide (NO) production and endothelial nitric oxide synthase (eNOS) phosphorylation through NOX-ROS pathway activation. Blocking this pathway reversed eNOS inhibition, restoring the endothelial benefits of simvastatin. Collectively, atypical antipsychotics impair statin efficacy in schizophrenia patients by activating the ADMA-NOX-ROS pathway, which downregulates LDLR in hepatocytes and inhibits eNOS activity in ECs. These findings underscore the need for tailored cardiovascular risk management strategies and identify potential molecular targets to enhance statin effectiveness in patients on atypical antipsychotics.

Advances in the molecular mechanisms of statins in regulating endothelial nitric oxide bioavailability: Interlocking biology between eNOS activity and L-arginine metabolism

Statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A, are widely used to treat hypercholesterolemia. In addition, statins have been suggested to reduce the risk of cardiovascular events owing to their pleiotropic effects on the vascular system, including vasodilation, anti-inflammation, anti-coagulation, anti-oxidation, and inhibition of vascular smooth muscle cell proliferation. The major beneficial effect of statins in maintaining vascular homeostasis is the induction of nitric oxide (NO) bioavailability by activating endothelial NO synthase (eNOS) in endothelial cells. The mechanisms underlying the increased NO bioavailability and eNOS activation by statins have been well-established in various fields, including transcriptional and post-transcriptional regulation, kinase-dependent phosphorylation and protein-protein interactions. However, the mechanism by which statins affect the metabolism of L-arginine, a precursor of NO biosynthesis, has rarely been discussed. Autophagy, which is crucial for energy homeostasis, regulates endothelial functions, including NO production and angiogenesis, and is a potential therapeutic target for cardiovascular diseases. In this review, in addition to summarizing the molecular mechanisms underlying increased NO bioavailability and eNOS activation by statins, we also discuss the effects of statins on the metabolism of L-arginine.