Apolipoprotein B-containing lipoproteins in atherogenesis

Concept and practice in the use of high-dose eicosapentaenoic acid for cardiovascular disease prevention in hypertriglyceridaemia

Genetic and epidemiological evidence indicates that triglyceride-rich lipoproteins are causal risk factors for atherosclerotic cardiovascular disease (ASCVD). Elevated levels of plasma triglyceride are common in patients who are diabetic or obese and contribute substantially to residual, ongoing risk of an ASCVD event in individuals on low-density lipoprotein (LDL)-lowering treatment. Hypertriglyceridaemia, therefore, presents a target for further intervention. Clinical trials have demonstrated that high-dose eicosapentaenoic acid (EPA) is effective in reducing ASCVD risk in patients on statin therapy, and it is now being incorporated into strategies using combination lipid-regulating treatment to manage aggressively those at highest risk. This review summarises the concepts underpinning the use of high-dose EPA alongside intensive LDL-lowering therapy, especially in the context of post-acute coronary syndrome. A practical implementation algorithm is presented setting out treatment options for combination therapy, and the place of high-dose EPA in ASCVD prevention in hypertriglyceridaemia.

Copper oxide nanoparticles disrupt lysosomal function and promote foam cell formation in RAW264.7 macrophages

Macrophage-derived foam cells are crucial in the development of atherosclerosis, a multifaceted and progressive disorder characterized by lipid and fibrous accumulation in major arteries. Copper oxide nanoparticles (CuONPs) have found widespread applications but their potential role in atherosclerosis remains understudied. In this study, we investigated the impact of CuONPs on foam cell formation in RAW264.7 macrophages. Our results showed that CuONPs, at concentrations as low as 10 μg/ml, significantly exacerbated foam cell formation induced by oxidized low-density lipoprotein (ox-LDL). Exposure to CuONPs stimulated LDL release and elevated the expression of NLRP3 inflammasome components, including NLRP3, Caspase-1, and IL-1β. Transmission electron microscopy (TEM) revealed accumulation of CuONPs within macrophage lysosomes, leading to disrupted lysosomal function. CuONPs-treated cells exhibited autophagosome accumulation due to impaired lysosomal degradation, as confirmed by Western blot analysis showing abnormal expression of LAMP-1 and LAMP-2 proteins. Flow cytometry analysis further demonstrated decreased lysosomal acidity in CuONPs-exposed cells. Our findings reveal a novel mechanism whereby CuONPs activate the inflammasome, disrupt lysosomal function, and hinder cholesterol efflux, thereby exacerbating the formation of macrophage-derived foam cells. These results highlight the potential risks of CuONPs exposure and provide important insights into the role of environmental particulate matter in the development of atherosclerosis.

ApoB-containing lipoproteins: count, type, size, and risk of coronary artery disease

BACKGROUND AND AIMS

Apolipoprotein B concentration reflects the number of atherogenic lipoproteins and is recognized as a key lipid risk marker. Whether the type or size of apoB particle (apoB-P) adds predictive value for coronary artery disease (CAD) remains unclear.

METHODS

A prospective analysis of 207 368 UK Biobank participants with comprehensive lipoprotein profiling and no prior history of atherosclerotic disease, diabetes, or active lipid-lowering therapy was conducted. Multivariable-adjusted Cox regression models were used to examine the association between each of the following lipid parameters with incident CAD: (i) nuclear magnetic resonance-measured apoB-P, (ii) concentrations of individual lipoprotein classes [very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL)], (iii) size subclasses, (iv) average particle diameter, and (v) immunoassay-measured lipoprotein(a) [Lp(a)].

RESULTS

A one standard deviation (SD) increase in apoB-P was associated with a 33% higher CAD risk [hazard ratio (HR): 1.33, 95% CI: 1.30-1.36]. Although VLDL particles were observed to carry a higher per-particle risk (HR per 100 nmol/L: 1.22, 1.11-1.34) compared with LDL (HR per 100 nmol/L: 1.07, 1.05-1.08), this difference was counterbalanced after considering relative particle abundance (LDL 91% vs VLDL 9% of total apoB-P). Thus the respective HR per 1-SD were 1.09 (1.05-1.14) and 1.24 (1.19-1.30). Particle diameter or size subclasses were not associated with CAD after apoB-P adjustment. The association of Lp(a) was robust even after apoB-P adjustment (HR:1.18, 1.16-1.20) and added independent prognostic value for CAD (area under curve: 0.769 vs 0.774, P < .001).

CONCLUSIONS

Lipid-related atherosclerotic risk is most accurately reflected by the total count of apoB-P and is largely unaffected by the major particle type (VLDL, LDL) or size. Elevated count of Lp(a) adds additional risk, and thus adequate assessment of atherogenic risk from dyslipidemia is best accomplished by consideration of both apoB-P and Lp(a) concentrations.

The CREscendoing promise of HDAC targeting to limit atherosclerosis

The factors that modulate the inflammatory response in atherosclerosis are not well defined. In this issue of Immunity, Asare et al. examine the impact of a cis-regulatory element (CRE) that controls expression of HDAC9 and find that HDAC9-mediated deacetylation of NLRP3 might be the mechanism by which genetic variants in this conserved CRE influence the inflammation associated with human atherosclerosis.