Insulin secretion impairment induced by rosuvastatin partly though autophagy in INS-1E cells

Comparative efficacy, toxicity, and insulin-suppressive effects of simvastatin and pravastatin in fatty acid-challenged mouse insulinoma MIN6 β-cell model

INTRODUCTION

Familial hypercholesterolemia, the highly prevalent form of dyslipidemia, is a well-known risk factor for premature heart disease and stroke worldwide. Statins, which inhibit 3-hydroxy 3-methylglutaryl coenzyme A (HMG-CoA) reductase, are the first-choice treatment for dyslipidemias, and have been effective in reducing the risk of stroke and myocardial infarction. However, emerging evidence indicates that statins may increase the incidence of new-onset type 2 diabetes by reducing β-cell mass and function. Notably, past in vitro reports studying the effects of statins on β-cells were performed without including free fatty acids in the model. This factor should have been addressed since these agents are used to treat individuals with hyperlipidemia.

METHODS

Here, we used a mouse insulinoma MIN6 β-cell culture model to assess the efficacy, cytotoxicity, and insulin-suppressive effects of simvastatin and pravastatin in the presence of palmitic, linoleic, and oleic acids cocktail to mimic mixed lipids challenge in a biologically relevant setting.

RESULTS AND DISCUSSION

Our findings indicate that simvastatin was more effective in lowering intracellular cholesterol but was more cytotoxic as compared to pravastatin. Similarly, simvastatin exhibited a higher suppression of total insulin content and insulin secretion. Both drugs suppressed insulin secretion in phases 1 and 2, dose-dependently. No significant effect was observed on mitochondrial respiration. More importantly, elution experiments showed that insulin content diminution by simvastatin treatment was reversible, while exogenous mevalonate did not improve total insulin content. This suggests that simvastatin's influence on insulin content is independent of its specific inhibitory action on HMG-CoA reductase. In conclusion, our study identified that simvastatin was more effective in lowering intracellular cholesterol, albeit it was more toxic and suppressive of β-cells function. Notably, this suppression was found to be reversible.

Risk and effect modifiers for poor glycemic control among the chinese diabetic adults on statin therapy: the kailuan study

BACKGROUND

Limited studies have investigated the association between statin therapy and poor glycemic control, especially in the Chinese diabetic population.

METHODS

Two prospective diabetes cohorts were drawn from the Kailuan Cohort. In Cohort 1, linear regression models were used to evaluate the association between statin therapy and glycated hemoglobin (HbA1c) level change. In Cohort 2, new user design and conditional logistic models were used to assess associations between statin initiation and poor glycemic control which was a composite outcome comprised of hypoglycemic agent escalation and new-onset hyperglycemia.

RESULTS

Among 11,755 diabetic patients with medication information, 1400 statin users and 1767 statin nonusers with repeated HbA1c measurements were included in Cohort 1 (mean age: 64.6 ± 10.0 years). After a median follow-up of 3.02 (1.44, 5.00) years, statin therapy was associated with higher HbA1c levels (β: 0.20%; 95%CI: 0.05% to 0.34%). In Cohort 2, 1319 pairs of matched cases/controls were included (mean age: 61.6 ± 9.75 years). After a median follow-up of 4.87 (2.51, 8.42) years, poor glycemic control occurred in 43.0% of statin new users and 31.8% of statin nonusers (OR: 1.69; 95% CI: 1.32 to 2.17; P < 0.001). The statin-associated poor glycemic control risk was significantly higher among patients with lower body mass index (Pint = 0.089). Furthermore, a nonlinear association was observed between statin therapy duration and poor glycemic control (P = 0.003).

CONCLUSIONS

Among Chinese diabetic adults, statin therapy was associated with a higher level of HbA1c, and a higher risk of hypoglycemic agent escalation and new-onset hyperglycemia, especially among those who had lower body mass index levels and longer statin therapy duration.

Bafilomycin 1A Affects p62/SQSTM1 Autophagy Marker Protein Level and Autophagosome Puncta Formation Oppositely under Various Inflammatory Conditions in Cultured Rat Microglial Cells

Regulation of autophagy through the 62 kDa ubiquitin-binding protein/autophagosome cargo protein sequestosome 1 (p62/SQSTM1), whose level is generally inversely proportional to autophagy, is crucial in microglial functions. Since autophagy is involved in inflammatory mechanisms, we investigated the actions of pro-inflammatory lipopolysaccharide (LPS) and anti-inflammatory rosuvastatin (RST) in secondary microglial cultures with or without bafilomycin A1 (BAF) pretreatment, an antibiotic that potently inhibits autophagosome fusion with lysosomes. The levels of the microglia marker protein Iba1 and the autophagosome marker protein p62/SQSTM1 were quantified by Western blots, while the number of p62/SQSTM1 immunoreactive puncta was quantitatively analyzed using fluorescent immunocytochemistry. BAF pretreatment hampered microglial survival and decreased Iba1 protein level under all culturing conditions. Cytoplasmic p62/SQSTM1 level was increased in cultures treated with LPS+RST but reversed markedly when BAF+LPS+RST were applied together. Furthermore, the number of p62/SQSTM1 immunoreactive autophagosome puncta was significantly reduced when RST was used but increased significantly in BAF+RST-treated cultures, indicating a modulation of autophagic flux through reduction in p62/SQSTM1 degradation. These findings collectively indicate that the cytoplasmic level of p62/SQSTM1 protein and autophagocytotic flux are differentially regulated, regardless of pro- or anti-inflammatory state, and provide context for understanding the role of autophagy in microglial function in various inflammatory settings.

Atorvastatin Induces Mitochondria-Dependent Ferroptosis via the Modulation of Nrf2-xCT/GPx4 Axis

As one of the cornerstones of clinical cardiovascular disease treatment, statins have an extensive range of applications. However, statins commonly used have side reactions, especially muscle-related symptoms (SAMS), such as muscle weakness, pain, cramps, and severe condition of rhabdomyolysis. This undesirable muscular effect is one of the chief reasons for statin non-adherence and/or discontinuation, contributing to adverse cardiovascular outcomes. Moreover, the underlying mechanism of muscle cell damage is still unclear. Here, we discovered that ferroptosis, a programmed iron-dependent cell death, serves as a mechanism in statin-induced myopathy. Among four candidates including atorvastatin, lovastatin, rosuvastatin, and pravastatin, only atorvastatin could lead to ferroptosis in human cardiomyocytes (HCM) and murine skeletal muscle cells (C2C12), instead of human umbilical vein endothelial cell (HUVEC). Atorvastatin inhibits HCM and C2C12 cell viability in a dose-dependent manner, accompanying with significant augmentation in intracellular iron ions, reactive oxygen species (ROS), and lipid peroxidation. A noteworthy investigation found that those alterations particularly occurred in mitochondria and resulted in mitochondrial dysfunction. Biomarkers of myocardial injury increase significantly during atorvastatin intervention. However, all of the aforementioned enhancement could be restrained by ferroptosis inhibitors. Mechanistically, GSH depletion and the decrease in nuclear factor erythroid 2-related factor 2 (Nrf2), glutathione peroxidase 4 (GPx4), and xCT cystine–glutamate antiporter (the main component is SLC7A11) are involved in atorvastatin-induced muscular cell ferroptosis and damage. The downregulation of GPx4 in mitochondria-mediated ferroptosis signaling may be the core of it. In conclusion, our findings explore an innovative underlying pathophysiological mechanism of atorvastatin-induced myopathy and highlight that targeting ferroptosis serves as a protective strategy for clinical application.