PEX3 promotes regenerative repair after myocardial injury in mice through facilitating plasma membrane localization of ITGB3.

The peroxisome is a versatile organelle that performs diverse metabolic functions. PEX3, a critical regulator of the peroxisome, participates in various biological processes associated with the peroxisome. Whether PEX3 is involved in peroxisome-related redox homeostasis and myocardial regenerative repair remains elusive. We investigate that cardiomyocyte-specific PEX3 knockout (Pex3-KO) results in an imbalance of redox homeostasis and disrupts the endogenous proliferation/development at different times and spatial locations. Using Pex3-KO mice and myocardium-targeted intervention approaches, the effects of PEX3 on myocardial regenerative repair during both physiological and pathological stages are explored. Mechanistically, lipid metabolomics reveals that PEX3 promotes myocardial regenerative repair by affecting plasmalogen metabolism. Further, we find that PEX3-regulated plasmalogen activates the AKT/GSK3ß signaling pathway via the plasma membrane localization of ITGB3. Our study indicates that PEX3 may represent a novel therapeutic target for myocardial regenerative repair following injury.

SIRT3-dependent mitochondrial redox homeostasis mitigates CHK1 inhibition combined with gemcitabine treatment induced cardiotoxicity in hiPSC-CMs and mice.

Administration of CHK1-targeted anticancer therapies is associated with an increased cumulative risk of cardiac complications, which is further amplified when combined with gemcitabine. However, the underlying mechanisms remain elusive. In this study, we generated hiPSC-CMs and murine models to elucidate the mechanisms underlying CHK1 inhibition combined with gemcitabine-induced cardiotoxicity and identify potential targets for cardioprotection. Mice were intraperitoneally injected with 25 mg/kg CHK1 inhibitor AZD7762 and 20 mg/kg gemcitabine for 3 weeks. hiPSC-CMs and NMCMs were incubated with 0.5 uM AZD7762 and 0.1 uM gemcitabine for 24 h. Both pharmacological inhibition or genetic deletion of CHK1 and administration of gemcitabine induced mtROS overproduction and pyroptosis in cardiomyocytes by disrupting mitochondrial respiration, ultimately causing heart atrophy and cardiac dysfunction in mice. These toxic effects were further exacerbated with combination administration. Using mitochondria-targeting sequence-directed vectors to overexpress CHK1 in cardiomyocyte (CM) mitochondria, we identified the localization of CHK1 in CM mitochondria and its crucial role in maintaining mitochondrial redox homeostasis for the first time. Mitochondrial CHK1 function loss mediated the cardiotoxicity induced by AZD7762 and CHK1-knockout. Mechanistically, mitochondrial CHK1 directly phosphorylates SIRT3 and promotes its expression within mitochondria. On the contrary, both AZD7762 or CHK1-knockout and gemcitabine decreased mitochondrial SIRT3 abundance, thus resulting in respiration dysfunction. Further hiPSC-CMs and mice experiments demonstrated that SIRT3 overexpression maintained mitochondrial function while alleviating CM pyroptosis, and thereby improving mice cardiac function. In summary, our results suggest that targeting SIRT3 could represent a novel therapeutic approach for clinical prevention and treatment of cardiotoxicity induced by CHK1 inhibition and gemcitabine.

Evaluating the Utility of Colchicine in Acute Coronary Syndrome: A Systematic Review and Meta-Analysis.

ABSTRACT: Colchicine has demonstrated promising effects in inhibiting local and systemic inflammation during acute coronary syndrome (ACS). However, the efficacy of colchicine in ACS is controversial. We performed a meta-analysis to assess the utility of colchicine in ACS by systematically searching randomized controlled trials. Recurrent myocardial infarction, coronary revascularization, and stroke were included as efficacy endpoint parameters whereas safety endpoints chosen were all-cause mortality, cardiovascular mortality, infectious events, and gastrointestinal (GI) adverse events. Nine identified studies were included (n = 7207 participants). Colchicine may reduce the risk of coronary revascularization by 54% [relative risk (RR) 0.46, 95% confidence interval (CI) 0.29-0.73; P < 0.01] and stroke by 61% (RR 0.39, 95%CI 0.18-0.81; P = 0.01). We observed no significant difference in all-cause mortality (RR 1.25, 95%CI 0.70-2.24; P = 0.46), cardiovascular mortality (RR 0.99, 95%CI 0.58-1.69; P = 0.98), recurrent myocardial infarction (RR 0.75, 95%CI 0.49-1.14; P = 0.18), and infectious events (RR 0.67, 95%CI 0.08-5.52; P = 0.71). Colchicine increased the risk of GI adverse reactions (RR 1.89, 95%CI 1.25-2.84; P < 0.01). Subgroup analysis of loading doses did not reveal significant differences in all endpoints (all P > 0.05), whereas subgroup analysis of follow-up periods showed a lower risk of GI adverse reactions with longer follow-up ( P < 0.01), which may be related to establishing tolerability. Trial sequential analysis suggested that further data are needed before definitive conclusions can be drawn. Colchicine may decrease the occurrence of stroke and revascularization in ACS, whereas slightly increasing the risk of GI reactions. The loading doses probably did not significantly improve the prognosis of patients.