The mechanisms of ferroptosis and its role in atherosclerosis.

Ferroptosis is a newly identified form of non-apoptotic programmed cell death, characterized by the iron-dependent accumulation of lethal lipid reactive oxygen species (ROS) and peroxidation of membrane polyunsaturated fatty acid phospholipids (PUFA-PLs). Ferroptosis is unique among other cell death modalities in many aspects. It is initiated by excessive oxidative damage due to iron overload and lipid peroxidation and compromised antioxidant defense systems, including the system Xc-/ glutathione (GSH)/glutathione peroxidase 4 (GPX4) pathway and the GPX4-independent pathways. In the past ten years, ferroptosis was reported to play a critical role in the pathogenesis of various cardiovascular diseases, e.g., atherosclerosis (AS), arrhythmia, heart failure, diabetic cardiomyopathy, and myocardial ischemia-reperfusion injury. Studies have identified dysfunctional iron metabolism and abnormal expression profiles of ferroptosis-related factors, including iron, GSH, GPX4, ferroportin (FPN), and SLC7A11 (xCT), as critical indicators for atherogenesis. Moreover, ferroptosis in plaque cells, i.e., vascular endothelial cell (VEC), macrophage, and vascular smooth muscle cell (VSMC), positively correlate with atherosclerotic plaque development. Many macromolecules, drugs, Chinese herbs, and food extracts can inhibit the atherogenic process by suppressing the ferroptosis of plaque cells. In contrast, some ferroptosis inducers have significant pro-atherogenic effects. However, the mechanisms through which ferroptosis affects the progression of AS still need to be well-known. This review summarizes the molecular mechanisms of ferroptosis and their emerging role in AS, aimed at providing novel, promising druggable targets for anti-AS therapy.

LncRNA HOXA11-AS promotes vascular endothelial cell injury in atherosclerosis by regulating the miR-515-5p/ROCK1 axis.

AIMS: Long non-coding RNA HOXA11-AS participated in heart disease. In this study, we aim to evaluate the potential roles of HOXA11-AS in atherosclerosis and its underlying mechanisms. METHODS AND RESULTS: The expression levels of HOXA11-AS in ox-LDL-treated HUVECs and arch tissues of high-fat diet-fed ApoE-/- mice (n = 10) were assessed by qRT-PCR. The effects of HOXA11-AS knockdown on the development of atherosclerosis were evaluated using in vitro and in vivo models. Luciferase reporter and RNA immunoprecipitation (RIP) assays verified the potential relationships between HOXA11-AS or ROCK1 and miR-515-5p. The interactive roles between HOXA11-AS and miR-515-5p and between miR-515-5p and ROCK1 were further characterized in ox-LDL-treated HUVECs. Our data showed that HOXA11-AS was significantly up-regulated (P < 0.001), whereas miR-515-5p was dramatically down-regulated in AS mice tissues (P < 0.001) and ox-LDL-treated HUVECs (P < 0.01). Ox-LDL could induce endothelial injuries by inhibiting cell proliferation (P < 0.001) and SOD synthesis (P < 0.001), promoting apoptosis (P < 0.01), ROS (P < 0.001), and MDA production (P < 0.001), increasing Bax (P < 0.001) and cleaved Caspase-3 (P < 0.001), and decreasing Bcl-2 (P < 0.001) and phosphorylated eNOS (P < 0.01). HOXA11-AS knockdown attenuated endothelial injuries via increasing eNOS phosphorylation. Luciferase assay and RIP results confirmed that miR-515-5p is directly bound to HOXA11-AS and ROCK1. HOXA11-AS promoted ox-LDL-induced HUVECs injury by directly inhibiting miR-515-5p from increasing ROCK1 expression and subsequently decreasing the expression and phosphorylation of eNOS. MiR-515-5p mimics could partially reverse the effects of HOXA11-AS knockdown. CONCLUSIONS: HOXA11-AS contributed to atherosclerotic injuries by directly regulating the miR-515-5p/ROCK1 axis. This study provided new evidence that HOXA11-AS might be a candidate for atherosclerosis therapy.

Community-acquired versus hospital-acquired acute kidney injury in patients with acute exacerbation of COPD requiring hospitalization in China.

Purpose: Previous studies have described the incidence, risk factors, and outcomes for patients with acute exacerbations of COPD (AECOPD) developing acute kidney injury (AKI). However, little is known about the differences between community-acquired AKI (CA-AKI) and hospital-acquired AKI (HA-AKI) in patients with AECOPD. Thus, in this study, we compared prevalence, risk factors, and outcomes for these patients with CA-AKI and HA-AKI. Patients and methods: This study was conducted from January 2014 to January 2017, and data from adult inpatients with AECOPD were analyzed retrospectively. A total of 1,768 patients were included, 280 patients were identified with CA-AKI and 97 patients were with HA-AKI. Results: Prevalence of CA-AKI was 15.8% and that of HA-AKI was 5.5%, giving an overall AKI prevalence of 21.3%. Patients with CA-AKI had a higher prevalence of chronic kidney disease (CKD) and lower prevalence of chronic cor pulmonale than patients with HA-AKI. Risk factors for developing HA-AKI and CA-AKI were similar, such as being elderly, requirement for mechanical ventilation, and a history of coronary artery disease and CKD. Patients with HA-AKI were more likely to have stage 3 AKI and worse short-term outcomes. In comparison with patients with CA-AKI, those with HA-AKI were more likely to require non-invasive mechanical ventilation (31.3% versus 16.8%; P = 0.003) and had a longer duration of mechanical ventilation (11 days versus 8 days; P = 0.020), longer hospitalization (14 days versus 12 days; P = 0.038), and higher inpatient mortality (32.0% versus 13.2%; P < 0.001). Patients with HA-AKI had worse (multivariate-adjusted) inpatient survival than those with CA-AKI (hazard ratio, 1.7 [95% confidence interval, 1.03-2.81; P = 0.038] for the HA-AKI group). Conclusion: AKI was common in patients with AECOPD requiring hospitalization. CA-AKI was more common than HA-AKI but otherwise demonstrated similar demographics and risk factors. Nevertheless, patients with HA-AKI had worse short-term outcomes.

A 6 hour therapeutic window, optimal for interventions targeting AMPK synergism and apoptosis antagonism, for cardioprotection against myocardial ischemic injury: an experimental study on rats.

The time relation between autophagy and myocardium ischemia (MI) has never been documented. Therefore, the present study was conducted to find out the exact timings and specific roles that AMP-activated protein kinase (AMPK)-mTOR signaling pathway plays on autophagy and apoptosis in rats' ischemic heart. 36 male Sprague Dawley (SD) rats were divided randomly into control and MI groups (each = 6). MI models were created by ligating left anterior descending artery (LAD) of rat hearts and the right myocardium were harvested at 0.5 h, 1 h, 3 h, 6 h, 12 h after ischimia. Expressions of Phosphorylated-AMPK (p-AMPK) and Phosphorylated-mTOR (p-mTOR) were determined by immunohistochemistry (IHC), western blotting (WB) and quantitative real-time PCR (Q-PCR) methods. LC3 expression was determined by WB and Q-PCR. The level of cell apoptosis was measured by the terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL) method. p-AMPK was activated significantly in ischemic myocardium and its expression at MI groups showed a time dependent pattern with a fluctuating pattern compared to the control group. p-AMPK levels were seen to rise at 0.5 h followed by a fall at 1 h after MI, which again gradually peaked at 6 h and finally decreased at 12 h. While, p-mTOR levels suggested a constant declining trend with time. Autophagy related protein LC3 had a sustained up-regulation with time. TUNEL method suggested that apoptosis increased at 0.5 h, then decreased at 1 h and 3 h after MI and finally showed a continuous rising trend. Activation of protective autophagy that occured during the initial phases of ischemic insults was within 6 hours. When the ischemia was prolonged, after 6 hours, although autophagy increased, cardiomyocyte death followed via the activation of apoptosis. Thus, limiting autophagy within 6 hours would give us double benefits. It would prevent the death related autophagy and prevent apoptotic cellular death. This 6 hours time period could serve as a landmark for therapeutic application for achieving cardioprotection from ischemic insults.