Abstract Background Routine apolipoprotein (apo) measurements for cardiovascular disease (CVD) are restricted to apoA-I and apoB. Here, the authors measured an unprecedented range of apolipoproteins ...in a prospective, population-based study and relate their plasma levels to risk of CVD. Objectives This study sought to measure apolipoproteins directly by mass spectrometry and compare their associations with incident CVD and to obtain a system-level understanding of the correlations of apolipoproteins with the plasma lipidome and proteome. Methods Associations of 13 apolipoproteins, 135 lipid species, and 211 other plasma proteins with incident CVD (91 events), defined as stroke, myocardial infarction, or sudden cardiac death, were assessed prospectively over a 10-year period in the Bruneck Study (N = 688) using multiple-reaction monitoring mass spectrometry. Changes in apolipoprotein and lipid levels following treatment with volanesorsen, a second-generation antisense drug targeting apoC-III, were determined in 2 human intervention trials, one of which was randomized. Results The apolipoproteins most significantly associated with incident CVD were apoC-II (hazard ratio per 1 SD HR/SD: 1.40; 95% confidence interval CI: 1.17 to 1.67), apoC-III (HR/SD: 1.38; 95% CI: 1.17 to 1.63), and apoE (HR/SD: 1.31; 95% CI: 1.13 to 1.52). Associations were independent of high-density lipoprotein (HDL) and non-HDL cholesterol, and extended to stroke and myocardial infarction. Lipidomic and proteomic profiles implicated these 3 very-low-density lipoprotein (VLDL)-associated apolipoproteins in de novo lipogenesis, glucose metabolism, complement activation, blood coagulation, and inflammation. Notably, apoC-II/apoC-III/apoE correlated with a pattern of lipid species previously linked to CVD risk. ApoC-III inhibition by volanesorsen reduced plasma levels of apoC-II, apoC-III, triacylglycerols, and diacylglycerols, and increased apoA-I, apoA-II, and apoM (all p < 0.05 vs. placebo) without affecting apoB-100 (p = 0.73). Conclusions The strong associations of VLDL-associated apolipoproteins with incident CVD in the general community support the concept of targeting triacylglycerol-rich lipoproteins to reduce risk of CVD.
Objectives This study sought to explore the association between baseline levels of microRNAs (miRNAs) (1995) and incident myocardial infarction (1995 to 2005) in the Bruneck cohort and determine ...their cellular origin. Background Circulating miRNAs are emerging as potential biomarkers. We previously identified an miRNA signature for type 2 diabetes in the general population. Methods A total of 19 candidate miRNAs were quantified by real-time polymerase chain reactions in 820 participants. Results In multivariable Cox regression analysis, 3 miRNAs were consistently and significantly related to incident myocardial infarction: miR-126 showed a positive association (multivariable hazard ratio: 2.69 95% confidence interval: 1.45 to 5.01, p = 0.002), whereas miR-223 and miR-197 were inversely associated with disease risk (multivariable hazard ratio: 0.47 95% confidence interval: 0.29 to 0.75, p = 0.002, and 0.56 95% confidence interval: 0.32 to 0.96, p = 0.036). To determine their cellular origin, healthy volunteers underwent limb ischemia-reperfusion generated by thigh cuff inflation, and plasma miRNA changes were analyzed at baseline, 10 min, 1 h, 5 h, 2 days, and 7 days. Computational analysis using the temporal clustering by affinity propagation algorithm identified 6 distinct miRNA clusters. One cluster included all miRNAs associated with the risk of future myocardial infarction. It was characterized by early (1 h) and sustained activation (7 days) post–ischemia-reperfusion injury and consisted of miRNAs predominantly expressed in platelets. Conclusions In subjects with subsequent myocardial infarction, differential co-expression patterns of circulating miRNAs occur around endothelium-enriched miR-126, with platelets being a major contributor to this miRNA signature.
Abstract Background Recent studies showed that lipoprotein(a) Lp(a) is a causal risk factor for cardiovascular disease (CVD). However, whether Lp(a) modifies clinical risk assessment was not ...established. Objectives This study was conducted to determine whether Lp(a) improves CVD risk prediction. Methods In 1995, Lp(a) was measured in 826 men and women (age range, 45 to 84 years) from the general community. Incidence of CVD was recorded over 15 years of follow-up. Results In models adjusted for Framingham Risk Score (FRS) and Reynolds Risk Score (RRS) variables, the hazard ratio (HR) for incident CVD was 1.37 per 1-SD higher Lp(a) level (SD = 32 mg/dl) and 2.37 when comparing the top fifth quintile with other quintiles. The addition of Lp(a) to the RRS increased the C-index by 0.016. Of the 502 subjects who remained free of CVD, 82 were correctly reclassified to a lower risk category and 49 were reclassified to a higher risk category (predicted 15-year categories: <7.5%, 7.5% to <15%, 15% to <30%, ≥30%) (p < 0.001). Of the 148 subjects who developed CVD, 18 were correctly reclassified to a higher risk category and 17 were reclassified to a lower risk category. In subjects at intermediate risk (15% to <30%), the net reclassification improvement afforded by Lp(a) was 22.5% for noncases, 17.1% for cases, and 39.6% overall. Allele-specific Lp(a) levels did not add to the predictive ability of the FRS or RRS or to Lp(a). Conclusions Elevated Lp(a) predicts 15-year CVD outcomes and improves CVD risk prediction. These findings suggest that Lp(a) levels may be used in risk assessment of subjects in the general community, particularly in intermediate-risk groups.
Objectives This study sought to assess the long-term predictive value and net reclassification for risk of cardiovascular disease (CVD) of biomarkers reflecting oxidation-specific epitopes (OSEs). ...Background OSEs are immunogenic, proinflammatory, and proatherogenic. The long-term predictive value and net reclassification of OSEs for risk of CVD events are not known. Methods Oxidized phospholipids on apolipoprotein B-100 (OxPL/apoB) and immunoglobulin (Ig)-G (IgG) and IgM autoantibodies to malondialdehyde-modified, low-density lipoprotein (MDA-LDL) and copper-oxidized LDL (Cu-OxLDL) were measured in 765 subjects in 1995 and 656 subjects in 2000 in the Bruneck study, representing 45- to 84-year-old men and women from the general community. Results Over 15 years of follow-up, 138 subjects reached the primary endpoint of incident CVD (ischemic stroke, myocardial infarction, new-onset unstable angina, acute coronary interventions, and vascular death). In a multivariable Cox model, the highest tertile of OxPL/apoB was associated with higher risk of CVD (hazard ratio HR: 2.4; 95% confidence interval CI: 1.5 to 3.7) and stroke (HR: 3.6; 95% CI: 1.8 to 7.4) compared with the lowest tertile. IgG Cu-OxLDLs were associated with higher risk of CVD, whereas IgM MDA-LDLs were associated with lower risk. Using OxPL/apoB, IgG Cu-OxLDL, and IgM MDA-LDL variables, the area under the curve (AUC) for CVD risk prediction increased from 0.664 (95% CI: 0.629 to 0.697) to 0.705 (95% CI: 0.672 to 0.737) (p = 0.048). The net reclassification index (NRI) was 0.163 (p = 0.0044) and 0.332 (p < 0.0001) in all subjects (n = 765) and in subjects with intermediate risk (n = 305), respectively. Of 627 subjects who remained free of CVD, 108 were correctly reclassified to a lower risk category, and 83 were reclassified to a higher category (categories: 15-year risk <15%, 15% to 30%, >30%). Conclusions OSE biomarkers predict 15-year CVD and stroke outcomes and provide potential clinical utility by reclassifying a significant proportion of individuals into higher or lower risk categories after traditional risk assessment.
Objectives This study sought to assess whether an antisense oligonucleotide (ASO) directed to apolipoprotein (a) apo(a) reduces apo(a) and lipoprotein (a) Lp(a) levels in transgenic mouse models. ...Background Elevated Lp(a) is a causal, independent, genetic risk factor for cardiovascular disease and myocardial infarction. Effective therapies to specifically lower plasma Lp(a) levels are lacking. Methods Three transgenic mouse models were utilized: 8K-apo(a) mice expressing 8 kringle IV (KIV) repeats with a single copy of KIV-2; 8K-Lp(a) mice expressing both the 8K apo(a) plus human apolipoprotein B-100; and 12K-apo(a) mice expressing a 12K apo(a) with 3 KIV-2 repeats. The mice were treated intraperitoneally with saline, a control ASO, or ASO 144367 directed to KIV-2 for 4 to 6 weeks. Apo(a), Lp(a), and oxidized phospholipids present on human apoB (OxPL/h-apoB) or apo(a) OxPL/apo(a) were measured at baseline and on and off therapy. Results ASO 144367 significantly reduced Lp(a) by 24.8% in 8K-Lp(a) mice, and reduced apo(a) levels by 19.2% in 8K-Lp(a) mice, 30.0% in 8K-apo(a) mice, and 86% in 12K-apo(a) mice; ASO 144367 also significantly reduced OxPL/apoB 22.4% in 8K-Lp(a) mice, and OxPL/apo(a) levels by 19.9% in 8K-Lp(a) mice, 22.1% in 8K-apo(a) mice, and 92.5% in 12K-apo(a) mice (p < 0.004, or less, for all). No significant changes occurred in Lp(a), apo(a), OxPL/apoB, or OxPL/apo(a) levels with control ASO or saline. Conclusions This study documents the first specific therapy, to our knowledge, for lowering apo(a)/Lp(a) levels and their associated OxPL. A more potent effect was documented in mice expressing apo(a) with multiple KIV-2 repeats. Targeting liver expression of apo(a) with ASOs directed to KIV-2 repeats may provide an effective approach to lower elevated Lp(a) levels in humans.
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