SIRT3 regulates cardiolipin biosynthesis in pressure overload-induced cardiac remodeling by PPARγ-mediated mechanism.

Cardiac remodeling is the primary pathological feature of chronic heart failure (HF). Exploring the characteristics of cardiac remodeling in the very early stages of HF and identifying targets for intervention are essential for discovering novel mechanisms and therapeutic strategies. Silent mating type information regulation 2 homolog 3 (SIRT3), as a major mitochondrial nicotinamide adenine dinucleotide (NAD)-dependent deacetylase, is required for mitochondrial metabolism. However, whether SIRT3 plays a role in cardiac remodeling by regulating the biosynthesis of mitochondrial cardiolipin (CL) is unknown. In this study, we induced pressure overload in wild-type (WT) and SIRT3 knockout (SIRT3-/-) mice via transverse aortic constriction (TAC). Compared with WT mouse hearts, the hearts of SIRT3-/- mice exhibited more-pronounced cardiac remodeling and fibrosis, greater reactive oxygen species (ROS) production, decreased mitochondrial-membrane potential (ΔΨm), and abnormal mitochondrial morphology after TAC. Furthermore, SIRT3 deletion aggravated TAC-induced decrease in total CL content, which might be associated with the downregulation of the CL synthesis related enzymes cardiolipin synthase 1 (CRLS1) and phospholipid-lysophospholipid transacylase (TAFAZZIN). In our in vitro experiments, SIRT3 overexpression prevented angiotensin II (AngII)- induced aberrant mitochondrial function, CL biosynthesis disorder, and peroxisome proliferator-activated receptor gamma (PPARγ) downregulation in cardiomyocytes; meanwhile, SIRT3 knockdown exacerbated these effects. Moreover, the addition of GW9662, a PPARγ antagonist, partially counteracted the beneficial effects of SIRT3 overexpression. In conclusion, SIRT3 regulated PPARγ-mediated CL biosynthesis, maintained the structure and function of mitochondria, and thereby protected the myocardium against cardiac remodeling.

Direct Oral Anticoagulants versus Vitamin K Antagonists in Cirrhotic Patients with Atrial Fibrillation: Update of Systematic Review and Meta-Analysis.

BACKGROUND: Prevention of ischemic stroke is an essential part of managing atrial fibrillation (AF). In recent years, direct oral anticoagulants (DOACs) have emerged as an alternative to vitamin K antagonists (VKAs). Little is understood regarding the efficacy and safety of DOACs in AF patients with liver cirrhosis (LC). OBJECTIVE: This meta-analysis is designed to evaluate the benefits and risks of DOACs compared to VKAs in AF patients with concomitant LC. METHODS: A thorough search was conducted in PubMed, Cochrane Library, Web of Science, Embase, Scopus, and CNKI databases up to February 2023. A total of seven clinical studies including 7551 patients were analyzed in this meta-analysis. All data analyses were performed using Review Manager software version 5.3. RESULTS: Regarding efficacy outcomes, DOACs had comparable clinical benefit in reducing ischemic stroke/systemic thromboembolism (HR=0.79, 95% CI [0.59, 1.06], p = 0.12) to VKAs. The incidence of all-cause death was similar between the DOACs and VKAs group (HR 0.94, 95% CI [0.69, 1.28], p = 0.69). Regarding safety outcomes, DOACs were associated with a significantly lower risk of major bleeding (HR 0.61, 95% CI [0.50, 0.75], p < 0.00001), intracranial hemorrhage (HR 0.55, 95% CI [0.31, 0.98], p = 0.04) and major gastrointestinal bleeding (HR 0.66, 95% CI [0.51, 0.85], p = 0.001) than VKAs. Additional subgroup analysis of advanced cirrhosis revealed that DOACs were associated with a significantly lower risk of major bleeding (HR 0.59, 95% CI [0.39, 0.89], p = 0.01) than VKAs. There were no significant differences between the DOACs and VKAs group concerning the incidence of ischemic stroke/systemic thromboembolism (HR 1.38, 95% CI [0.75, 2.55], p = 0.31) and major gastrointestinal bleeding (HR 0.65, 95% CI [0.41, 1.04], p = 0.08). CONCLUSION: DOACs are associated with more favorable safety outcomes and may be a feasible option of oral anticoagulant for individuals with atrial fibrillation and cirrhosis. Pending validation by randomized prospective studies, the findings of this study should be interpreted with caution.

Endothelial cells microparticle-associated protein disulfide isomerase promotes platelet activation in metabolic syndrome.

BACKGROUND: Metabolic syndrome (MetS) is a common challenge in the world, and the platelet activation is enhanced in MetS patients. However, the fundamental mechanism that underlies platelet activation in MetS remains incompletely understood. Endothelial cells are damaged seriously in MetS patients, then they release more endothelial microparticles (EMPs). After all, whether the EMPs participate in platelet activation is still obscure. If they were, how did they work? RESULTS: We demonstrated that the levels of EMPs, PMPs (platelet derived microparticles) and microparticle-carried-PDI activity increased in MetS patients. IR endothelial cells released more EMPs, the EMP-PDI was more activated. EMPs can enhance the activation of CD62P, GPIIb/IIIa and platelet aggregation and this process can be partly inhibited by PDI inhibitor such as RL90 and rutin. Activated platelets stimulated by EMPs expressed more PDI on cytoplasm and released more PMPs. MATERIALS AND METHODS: We obtained plasma from 23 MetS patients and 8 normal healthy controls. First we built insulin resistance (IR) model of human umbilical vein endothelial cells (HUVECs), and then we separated EMPs from HUVECs culture medium and used these EMPs to stimulate platelets. Levels of microparticles, P-selectin(CD62P), Glycoprotein IIb/IIIa (GPIIb/IIIa) were detected by flow cytometry and levels of EMPs were detected by enzyme-linked immunosorbent assay (ELISA). The protein disulfide isomerase (PDI) activity was detected by insulin transhydrogenase assay. Platelet aggregation was assessed by turbidimetry. CONCLUSION: EMPs can promote the activation of GPIIb/IIIa in platelets and platelet aggregation by the PDI which is carried on the surface of EMPs.