Plasma apolipoprotein C-III levels, triglycerides, and coronary artery calcification in type 2 diabetics

A Qamar, SA Khetarpal, AV Khera… - … , and vascular biology, 2015 - Am Heart Assoc
A Qamar, SA Khetarpal, AV Khera, A Qasim, DJ Rader, MP Reilly
Arteriosclerosis, thrombosis, and vascular biology, 2015Am Heart Assoc
Objective—Triglyceride-rich lipoproteins have emerged as causal risk factors for developing
coronary heart disease independent of low-density lipoprotein cholesterol levels.
Apolipoprotein C-III (ApoC-III) modulates triglyceride-rich lipoprotein metabolism through
inhibition of lipoprotein lipase and hepatic uptake of triglyceride-rich lipoproteins. Mutations
causing loss-of-function of ApoC-III lower triglycerides and reduce coronary heart disease
risk, suggestive of a causal role for ApoC-III. Little data exist about the relationship of ApoC …
Objective
Triglyceride-rich lipoproteins have emerged as causal risk factors for developing coronary heart disease independent of low-density lipoprotein cholesterol levels. Apolipoprotein C-III (ApoC-III) modulates triglyceride-rich lipoprotein metabolism through inhibition of lipoprotein lipase and hepatic uptake of triglyceride-rich lipoproteins. Mutations causing loss-of-function of ApoC-III lower triglycerides and reduce coronary heart disease risk, suggestive of a causal role for ApoC-III. Little data exist about the relationship of ApoC-III, triglycerides, and atherosclerosis in patients with type 2 diabetes mellitus (T2DM). Here, we examined the relationships between plasma ApoC-III, triglycerides, and coronary artery calcification in patients with T2DM.
Approach and Results
Plasma ApoC-III levels were measured in a cross-sectional study of 1422 subjects with T2DM but without clinically manifest coronary heart disease. ApoC-III levels were positively associated with total cholesterol (Spearman r=0.36), triglycerides (r=0.59), low-density lipoprotein cholesterol (r=0.16), fasting glucose (r=0.16), and glycosylated hemoglobin (r=0.12; P<0.0001 for all). In age, sex, and race-adjusted analysis, ApoC-III levels were positively associated with coronary artery calcification (Tobit regression ratio, 1.78; 95% confidence interval, 1.27–2.50 per SD increase in ApoC-III; P<0.001). As expected for an intermediate mediator, these findings were attenuated when adjusted for both triglycerides (Tobit regression ratio, 1.43; 95% confidence interval, 0.94–2.18; P=0.086) and separately for very low–density lipoprotein cholesterol (Tobit regression ratio, 1.14; 95% confidence interval, 0.75–1.71; P=0.53).
Conclusions
In persons with T2DM, increased plasma ApoC-III is associated with higher triglycerides, less favorable cardiometabolic phenotypes, and higher coronary artery calcification, a measure of subclinical atherosclerosis. Therapeutic inhibition of ApoC-III may thus be a novel strategy for reducing plasma triglyceride-rich lipoproteins and cardiovascular risk in T2DM.
Am Heart Assoc