Multiparametric profiling of cellular lipid metabolism in hypercholesterolemia

Rationale: Identification of cellular defects underlying the development of hypercholesterolemia in individual persons remains challenging. Quantification of low-density lipoprotein (LDL) uptake can be used to characterize the effects of LDL receptor (LDLR) variants. However, a systematic assessment of LDL uptake in healthy individuals, persons with increased polygenic risk, or carriers of identical LDLR mutations is lacking. Furthermore, establishment of additional quantitative parameters related to lipid storage might provide deeper insight into the disease. Objective: We aimed to establish a scalable analysis pipeline enabling reliable quantification of LDL uptake and lipid storage in primary cells, to elucidate defects underlying hypercholesterolemia in individual patients. Methods: We set up a multi-parametric imaging platform for the quantification of lipid uptake and storage in cytoplasmic droplets of leukocyte populations from peripheral blood. We defined a new quantifiable parameter, cellular lipid mobilization, describing the efficiency at which cells deplete their lipid reservoirs. Results: The 65 individuals studied, including heterozygous familial hypercholesterolemia (He-FH) patients with identical LDL receptor mutations, showed distinct profiles of LDL uptake and lipid mobilization. LDL uptake was lower in individuals with higher body mass index (BMI). Lipid mobilization correlated positively with LDL uptake and negatively with hypercholesterolemia, BMI and age. He-FH patients with remaining hypercholesterolemia despite statin treatment displayed low LDL uptake and lipid mobilization, suggesting that these readouts may help to pinpoint individuals in need of more effective lipid lowering regimen. Moreover, their combination with a polygenic risk score for LDL cholesterol (LDL-c) explained hypercholesterolemia better than the genetic risk score alone. Conclusions: This study highlights the heterogeneity of hypercholesterolemia aetiology in individual patients and demonstrates regulation of intracellular lipid storage as a novel quantifiable parameter in the disease. The cell-based assays established are compatible with a high-throughput format and have potential for improving personalized management of hypercholesterolemia.