Groenen, A. G. | Search bioRxiv

bioRxiv2026

Associations Between Plasma Lipoprotein(a) Levels and Circulating Monocyte Subsets Differ across Populations

BackgroundLipoprotein(a) [Lp(a)] is a causal risk factor for cardiovascular disease (CVD), with plasma concentrations higher in Black individuals than in White individuals. Published findings support a model in which high Lp(a), in part through oxidized phospholipid (oxPL)-mediated signaling, promotes a pro-inflammatory monocyte phenotype that may contribute to arterial wall inflammation and the development of CVD. Here, we examined the relationship between Lp(a) concentrations and isoform size and the distribution of circulating monocyte populations in Black and White individuals using single-cell RNA sequencing (scRNA-seq) data. MethodsUsing standardized assays, we measured plasma Lp(a) levels, isoform size, inflammatory markers, and oxidized phospholipids in stored plasma samples from our previously published cohort of 128 participants. After excluding smokers and individuals with type II diabetes, a total of 34 participants (20 Black participants, 14 White participants) were included in analyses. Participants were further stratified by plasma Lp(a) levels into normal Lp(a) [median 12.6 nmol/L, with 15 individuals (8 Black participants) and high Lp(a) (median 159 nmol/L, with 19 individuals (12 Black partcipants)]. Multivariable linear regression was used to assess the association between plasma Lp(a) levels, Lp(a)-oxPL, and the proportion of monocyte subsets. Across all participants, scRNA-seq data identified six classical monocyte subsets, one non-classical monocyte subset, one MHCIIhi monocyte subset, and one interferon (IFN)-responsive monocyte subset. ResultsThe distribution of monocyte subsets was similar in individuals with normal versus high Lp(a) levels. Despite the small study cohort, self resported race modified the assocation between plasma Lp(a) levels and the proportion of non-classical monocytes (P = 0.032), which was inversely associated in White participants (P = 0.028), but not in Black partcipatns (P = 0.470). OxPL bound to APO(a) showed a positive correlation with plasma Lp(a) levels (R2 = 0.84; P = 3.3x10-14), and non-classical monocytes (PWhites = 0.027; PBlacks = 0.275; PInteraction = 0.014). Race also modified the association between plasma Lp(a) levels and the proportion of classical 2 monocytes (P = 0.027). ConclusionsThese results underscore the importance of self reported race when analysing studies on Lp(a), monocytes and, cardiovascular related monocyte immune functions.

immunology↗

bioRxiv2022

T cell cholesterol efflux suppresses apoptosis and senescence and increases atherosclerosis in middle aged mice

Atherosclerosis is a chronic inflammatory disease driven by hypercholesterolemia. During aging, T-cells accumulate cholesterol, which could lead to a pro-inflammatory phenotype. However, the role of cholesterol efflux pathways mediated by ATP-binding cassette A1 and G1 (ABCA1/ABCG1) in T-cell-dependent age-related inflammation and atherosclerosis remains poorly understood. In this study, we generated mice with T-cell-specific Abca1/Abcg1-deficiency on the low-density-lipoprotein-receptor deficient (Ldlr-/-) background. T-cell Abca1/Abcg1-deficiency decreased blood, lymph node, and splenic T-cells, and increased T-cell activation and apoptosis. T-cell Abca1/Abcg1-deficiency induced a premature T-cell aging phenotype in middle-aged (12-13 months) Ldlr-/- mice, reflected by upregulation of senescence markers. Despite T-cell senescence and enhanced T-cell activation, T-cell Abca1/Abcg1-deficiency decreased atherosclerosis and aortic inflammation in middle-aged Ldlr-/- mice, accompanied by decreased T-cells in atherosclerotic plaques. We attribute these effects to T-cell apoptosis downstream of T-cell activation. Collectively, T-cell cholesterol efflux pathways are critical for maintaining T-cell numbers, suppress senescence, and induce atherosclerosis in middle-aged Ldlr-/- mice.

immunology↗