Monocyte subset distribution in patients with stable atherosclerosis and elevated levels of lipoprotein(a)

•Lipoprotein(a) serves as an independent risk factor in atherosclerotic disease.•Monocyte subsets exhibit distinct inflammatory and atherogenic properties.•Patients with elevated levels of Lp(a) show a shift towards intermediate monocytes.•This association was independent of clinical properties and inflammatory markers.•Those patients also exhibited higher OxPL/apoB concentrations.

BackgroundLipoprotein(a) (Lp(a)) is a proatherogenic plasma lipoprotein currently established as an independent risk factor for the development of atherosclerotic disease and as a predictor for acute thrombotic complications. In addition, Lp(a) is the major carrier of proinflammatory oxidized phospholipids (OxPL). Today, atherosclerosis is considered to be an inflammatory disease of the vessel wall in which monocytes and monocyte-derived macrophages are crucially involved. Circulating monocytes can be divided according to their surface expression pattern of CD14 and CD16 into at least 3 subsets with distinct inflammatory and atherogenic potential.ObjectiveThe aim of this study was to examine whether elevated levels of Lp(a) and OxPL on apolipoprotein B-100-containing lipoproteins (OxPL/apoB) are associated with changes in monocyte subset distribution.MethodsWe included 90 patients with stable coronary artery disease. Lp(a) and OxPL/apoB were measured, and monocyte subsets were identified as classical monocytes (CMs; CD14++CD16−), intermediate monocytes (IMs; CD14++CD16+), and nonclassical monocytes (NCMs; CD14+CD16++) by flow cytometry.ResultsIn patients with elevated levels of Lp(a) (>50 mg/dL), monocyte subset distribution was skewed toward an increase in the proportion of IM (7.0 ± 3.8% vs 5.2 ± 3.0%; P = .026), whereas CM (82.6 ± 6.5% vs 82.0 ± 6.8%; P = .73) and NCM (10.5 ± 5.3 vs 12.8 ± 6.0; P = .10) were not significantly different. This association was independent of clinical risk factors, choice of statin treatment regime, and inflammatory markers. In addition, OxPL/apoB was higher in patients with elevated Lp(a) and correlated with IM but not CM and NCM.ConclusionsIn conclusion, we provide a potential link between elevated levels of Lp(a) and a proatherogenic distribution of monocyte subtypes in patients with stable atherosclerotic disease.