Current clinical guidelines consider low-density lipoprotein cholesterol (LDL-C) to be the primary causal risk factor (and target for therapeutic intervention) for coronary heart disease and ischemic stroke. Despite this, in the United States, routine cholesterol tests typically only capture measurements of total triglycerides, total cholesterol and high-density lipoprotein cholesterol (HDL-C); failing to provide information on the size, density, concentrations or compositions of lipoproteins.
In addition, evidence from observational studies and randomized control trials have provided an incomplete and inconsistent picture of the role lipid and lipoprotein subclasses play in the etiology of CVD subtypes, in particular stroke subtypes (ischemic stroke and intracerebral hemorrhage). To break down broad “composite” lipid traits (as captured by standard assays that quantify the sum of lipids across lipoproteins), detailed lipoprotein phenotyping techniques can be obtained through Nuclear Magnetic Resonance spectroscopy (NMR).
In a large nested case-control study, Holmes and colleagues used Nightingale’s high-throughput NMR-based assay to quantify 225 metabolic markers, including detailed lipid and lipoprotein particle profiles, for 4662 individuals with risk of incident myocardial infarction, ischemic stroke and intracerebral hemorrhage within the China Kadoorie Biobank. A range of associations were investigated with risk of incident vascular disease, using logistic regression adjusted for age, sex, geographical region, and environmental factors (e.g. smoking and education). Many of the associations reported are novel and inform our current understanding of atherogenic lipid profiles.
Dyslipidaemia is an established risk factor for myocardial infarction, but there is uncertainty linking its causality to different lipids and lipoprotein particles. Overall, VLDL particle concentrations were found to be as strongly associated with myocardial infarction and ischemic stroke as LDL particles. In addition, triglycerides displayed more consistent relationships with myocardial infarction and ischemic stroke than cholesterol when in apo-B containing lipoproteins (VLDL, IDL and LDL). These findings reinforce a proposed causal role for remnant cholesterol in VLDL from large-scale Mendelian randomization studies.
Surprisingly, none of 61 NMR-quantified measures of lipoprotein particle concentrations, compositions, size or apolipoproteins were found to associate with intracerebral hemorrhage. This is contrary to previous findings that suggested low cholesterol or triglyceride levels may confer a higher risk of intracerebral hemorrhage. However, glucose, beta-hydroxybutyrate, acetoacetate, and creatinine did show positive associations with intracerebral hemorrhage risk. Of particular note, GlycA (a well-reported NMR composite marker of inflammation) was found to strongly associate with myocardial infarction, ischemic stroke and intracerebral hemorrhage risk.
Taken together, these findings indicate lipoprotein-specific associations of cholesterol and triglycerides with the risk of myocardial infarction and ischemic stroke. In contrast, lipid composition and lipoprotein subclasses are unlikely to be implicated in intracerebral hemorrhage. Glucose and inflammation pathways potentially span these three vascular endpoints, opening up areas for further study. Therapeutic targets for vascular disease subtypes could extend beyond LDL-C, to include: VLDL, fatty acid composition and triglycerides. Facilitating the demand for metabolomics screening of population cohorts and biobanks to assess CVD risk, Nightingale’s high-throughput, affordable and standardized NMR-based metabolomics assay allows for detailed phenotyping of lipids and lipoprotein subclasses. Nightingale’s panel includes lipid concentrations and compositions of 14 lipoprotein subclasses, along with measures of amino acids, glycolysis related metabolites, ketone bodies and fatty acids.
An editorial comment accompanying this study (Mayr, M et al. JACC) proposes widespread application of NMR-based lipoprotein and apolipoprotein profiling, it states:
“It is time to advance … profiling to meet the high throughput, low cost, and standardization required for potential clinical use. The application of multiomics technologies may pave the way toward redefining CVD risk.”
This study is an example of Nightingale's NMR metabolomics platform being applied in cardiovascular disease research. Our blood analysis service can be utilized to investigate the molecular mechanisms underpinning the risk of myocardial infarction (heart attack), and common stroke subtypes, such as ischemic stroke and intracerebral hemorrhage. In this study, Nightingale’s assay was used to quantify metabolic measures (including detailed lipid and lipoprotein particle profiles), for 4662 individuals with risk of incident myocardial infarction, ischemic stroke and intracerebral hemorrhage in a nested case-control study within the China Kadoorie Biobank.
This is one of the largest studies to date utilizing Nightingale’s technology to investigate the relationship of blood-based metabolites associated with risk of incident vascular disease subtypes, with researchers investigating 3196 disease cases. Nightingale's assay has been successfully used in a wide range of research applications and has featured in over 100 peer-reviewed studies.