Lipid droplets (LDs) are found in nearly all eukaryotic cells, and each consists of a neutral lipid core enveloped by a phospholipid monolayer and surface proteins ( 1 ). The main lipids found in the cores of LDs are triacylglycerols (TGs) and sterol esters (SEs). Whether TGs are required for the formation of LDs is unknown. The major known enzymes that catalyze TG synthesis in mammals are the acyl CoA:diacylglycerol acyltransferases (DGAT; Fig. 1A ) ( 2 ), which catalyze the covalent addition of a fatty acyl chain to diacylglycerol. Genetic deletion of DGAT1 in mice revealed that this enzyme is not essential and that DGAT1 knockout (DGAT1 KO) mice have reductions in TG levels in many tissues, including adipose tissue, when fed a high-fat diet ( 3 ). Deletion of DGAT2 revealed that this enzyme is essential: mice lacking DGAT2 have severe reductions in TG levels and die shortly after birth ( 4 ). Nevertheless, newborn DGAT2 KO mice do have some TG, which may be due to DGAT1 activity. Given that enzymes in both the DGAT1 (MBOAT, 16 family members) and DGAT2 (7 members) families possess many different lipid acyltransferase activities ( 5, 6 ), and that several of these Abstract The total contribution of the acyl CoA:diacylglycerol acyltransferase (DGAT) enzymes, DGAT1 and DGAT2, to mammalian triacylglycerol (TG) synthesis has not been determined. Similarly, whether DGAT enzymes are required for lipid droplet (LD) formation is unknown. In this study, we examined the requirement for DGAT enzymes in TG synthesis and LDs in differentiated adipocytes with genetic deletions of DGAT1 and DGAT2. Adipocytes with a single deletion of either enzyme were capable of TG synthesis and LD formation. In contrast, adipocytes with deletions of both DGATs were severely lacking in TG and did not have LDs, indicating that DGAT1 and DGAT2 account for nearly all TG synthesis in adipocytes and appear to be required for LD formation during adipogenesis. DGAT enzymes were not absolutely required for LD formation in mammalian cells, however; macrophages defi cient in both DGAT enzymes were able to form LDs when incubated with cholesterolrich lipoproteins. Although adipocytes lacking both DGATs had no TG or LDs, they were fully differentiated by multiple criteria.Our fi ndings show that DGAT1 and DGAT2 account for the vast majority of TG synthesis in mice, and DGAT function is required for LDs in adipocytes, but not in all cell

The niacin receptor GPR109A is a Gi-protein coupled receptor which mediates the effects of niacin on inhibiting intracellular triglyceride lipolysis in adipocytes. However, the role of GPR109A in mediating the effects of niacin on high density lipoprotein (HDL) metabolism is unclear. We found niacin has no effect on HDL-C in GPR109A knockout mice. Furthermore, niacin lowered intracellular cAMP in primary hepatocytes mediated by GPR109A. We used an adeno-associated viral (AAV) serotype 8 vector encoding GPR109A under the control of the hepatic-specific thyroxine-binding globulin promoter to specifically overexpress GPR109A in mouse liver. Plasma HDL-C, hepatic ABCA1 and the HDL cholesterol production rate were significantly reduced in mice overexpressing GPR109A. Overexpression of GPR109A reduced primary hepatocyte free cholesterol efflux to apoA-I; conversely, GPR109A deficient hepatocytes had increased ABCA1-mediated cholesterol efflux. These data support the concept that the HDL-C lowering effect of niacin in wild-type mice is mediated through stimulation of GPR109A in hepatocytes; such an effect then leads to reduced hepatocyte ABCA1 expression and activity, decreased cholesterol efflux to nascent apoA-I, and reduced HDL-C levels. These results indicate that niacin-mediated activation of GP109A in liver lowers ABCA1 expression leading to reduced hepatic cholesterol efflux to HDL.

The modification of cholesterol efflux capacity (CEC) by current medications and interventions has been investigated in both large randomized control trials and smaller observational cohorts. This review serves to compile the results of these studies and evaluate CEC modulation by commonly used medications. Altering CEC could be a novel therapeutic approach to improving cardiovascular risk profiles.

There are gaps in the use of therapies that save lives and improve quality of life for patients with heart failure with reduced ejection fraction, both in the US and abroad. The evidence is clear that initiation and titration of guideline-directed medical therapy (GDMT) and comprehensive disease-modifying medical therapy (CDMMT) to maximally tolerated doses improves patient-focused outcomes, yet observational data suggest this does not happen. The purpose of this review is to describe the gap in the use of optimal treatment worldwide and discuss the benefits of newer heart failure therapies including angiotensin receptor-neprilysin inhibitors and sodium-glucose cotransporter 2 inhibitors. It will also cover the efficacy and safety of such treatments and provide potential pathways for the initiation and rapid titration of GDMT/CDMMT.

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Body mass index ≥50 kg/m was independently associated with female sex and LVH but not with hypertension, diabetes, or a higher rate of surgical complications.

IntroductionThe impact of colchicine on hospitalized patients with Coronavirus disease-19 (COVID-19) related cardiac injury is unknown.Materials and MethodsIn this multicenter randomized controlled open-label clinical trial, we randomized hospitalized adult patients with documented COVID-19 and evidence of cardiac injury in a 1:1 ratio to either colchicine 0.6 mg po twice daily for 30 days plus standard of care or standard of care alone. Cardiac injury was defined as elevated cardiac biomarkers, new arrhythmia, new/worsened left ventricular dysfunction, or new pericardial effusion. The primary endpoint was the composite of all-cause mortality, need for mechanical ventilation, or need for mechanical circulatory support (MCS) at 90 days. Key secondary endpoints included the individual components of the primary endpoint and change in and at least 2-grade reduction in the World Health Organization (WHO) Ordinal Scale at 30 days. The trial is registered with clinicaltrials.gov (NCT04355143).ResultsWe enrolled 93 patients, 48 patients in the colchicine arm and 45 in the control arm. There was no significant difference in the primary outcome between the colchicine and control arms (19 vs. 15%, p = 0.78), nor in the individual components of all-cause mortality (17 vs. 15%, p = 1.0) and need for mechanical ventilation (8 vs. 5%, p = 0.68); no patients in either group required MCS. The change in (−1.8 ± 2.4 vs. −1.2 ± 2.0, p = 0.12) and at least 2-grade reduction (75 vs. 75%, p = 1.0) in the WHO ordinal scale was also similar between groups.ConclusionPatients hospitalized with COVID-19 and evidence of cardiac injury did not benefit from colchicine therapy.