Dyslipidemia in the Young: From Genotype to Treatment

The data presented in this thesis call for: (1) global improvement in the identification of hypercholesterolemia in young individuals by using age- and gender-specific plasma LDL-c levels. These individuals have an increased lifetime risk of CVD – especially those suffering from FH – and personalized advice on lifestyle changes and cholesterol lowering medication should be considered; (2) promotion of the understanding and stimulation of using cardiovascular risk prevention guidelines; and (3) further studies to explore novel pathways implicated in disturbances of LDL metabolism as well as investigate genetic targets like STAP1 that ultimately could lead to improved diagnosis and treatment of dyslipidemia

Physical fitness and modifiable cardiovascular disease risk factors in survivors of childhood cancer: A report from the SURfit study

Background: Childhood cancer survivors are at risk for cardiovascular disease (CVD) because of intensive cancer therapies often accompanied by an unhealthy lifestyle. This study was aimed at 1) describing modifiable CVD risk factors in survivors and 2) investigating the association between different aspects of physical fitness and CVD risk factors. Methods: The authors analyzed cross-sectional data from ≥5-year survivors who were 16 years old or younger at their cancer diagnosis and 16 years old or older at the time of the study. Single CVD risk factors (waist circumference, blood pressure, fasting glucose, inverse high-density lipoprotein, and triglycerides), a composite CVD risk score (combined z scores of all CVD risk factors), and metabolic syndrome were evaluated. Physical fitness measures included cardiopulmonary exercise testing (CPET), a handgrip test, and a 1-minute sit-to-stand test (STS). Multivariable logistic regression was used for the association between fitness measures and CVD risk factors, with adjustments made for demographic factors and cancer therapy. Results: This study included 163 survivors with a median age at diagnosis of 7 years and a median age at the time of the study of 28 years. Among those survivors, 27% had a high waist circumference, 32% had high blood pressure, 19% had high triglycerides, 20% had an increased composite CVD risk score, and 10% had metabolic syndrome. A better performance during CPET, handgrip testing, and STS was associated with a lower probability of having a high waist circumference, high triglycerides, and metabolic syndrome. Conclusions: Better aerobic fitness (CPET) and, to a lesser extent, handgrip and STS were associated with fewer CVD risk factors. Further investigations are warranted to investigate which fitness measures should preferably be used to screen survivors to promote physical activity in those with impaired test performance. Lay summary: This study investigated the relationship between physical fitness of adult childhood cancer survivors and their risk factors for cardiovascular disease. Cardiovascular risk factors such as high blood pressure, a high waist circumference, and high blood lipids were frequently found in childhood cancer survivors. Survivors with better physical fitness (measured by a cycling test or simple strength and endurance tests) had a lower chance of having cardiovascular risk factors. This suggests that childhood cancer survivors could benefit from physical activity and general fitness by increasing their physical fitness and possibly decreasing their risk of cardiovascular disease. Keywords: cardiovascular disease; childhood cancer survivors; exercise test; metabolic syndrome; physical fitness

Large HDL particles negatively associate with leukocyte counts independent of cholesterol efflux capacity:A cross sectional study in the population-based LifeLines DEEP cohort

BACKGROUND AND AIMS: Leukocytosis, the expansion of white blood cells, is associated with increased cardiovascular risk. Studies in animal models have shown that high-density lipoprotein cholesterol (HDL-c) suppresses leukocytosis by mediating cholesterol efflux from hematopoietic stem and progenitor cells. HDL-c showed a moderate negative association with leukocyte numbers in the UK Biobank and Multi-Ethnic Study of Atherosclerosis. Cholesterol efflux capacity of HDL (HDL-CEC) or HDL particle (HDL-P) number has been proposed as improved inverse predictor of CVD compared to plasma HDL-c. In the LifeLines DEEP (LLD) cohort (n = 962), a sub-cohort representing the prospective population-based LL cohort from the North of The Netherlands, we tested the hypothesis that HDL-CEC and HDL-P were associated with lower leukocyte counts. METHODS: We carried out multivariable regression and causal mediation analyses (CMA) to test associations between HDL-c, HDL-CEC, or HDL-P and leukocyte counts. We measured HDL-CEC in THP-1 macrophages and HDL-P and composition using nuclear magnetic resonance. RESULTS: HDL-c associated negatively with leukocyte counts, as did extra-large and large HDL-P, while HDL-CEC showed no association. Each one-standard deviation (SD) increase in extra-large HDL-P was associated with 3.0% and 4.8% lower leukocytes and neutrophils, respectively (q < 0.001). In contrast, plasma concentration of small HDL-P associated positively with leukocyte and neutrophil counts, as did small HDL-P triglycerides (TG) and total plasma TG. CMA showed that the association between S-HDL-P and leukocytes was mediated by S-HDL-TG. CONCLUSIONS: The association between HDL-P and leukocyte counts in the general population is dependent on HDL-P size and composition, but not HDL-CEC

Use of plasma metabolomics to analyze phenotype-genotype relationships in young hypercholesterolemic females

Hypercholesterolemia is characterized by high plasma LDL cholesterol and often caused by genetic mutations in LDL receptor (LDLR), APOB, or proprotein convertase subtilisin/kexin type 9 (PCSK9). However, a substantial proportion of hypercholesterolemic subjects do not have any mutations in these canonical genes, leaving the underlying pathobiology to be determined. In this study, we investigated to determine whether combining plasma metabolomics with genetic information increases insight in the biology of hypercholesterolemia. For this proof of concept study, we combined plasma metabolites from 119 hypercholesterolemic females with genetic information on the LDL canonical genes. Using hierarchical clustering, we identified four subtypes of hypercholesterolemia, which could be distinguished along two axes represented by triglyceride and large LDL particle concentration. Subjects with mutations in LDLR or APOB preferentially clustered together, suggesting that patients with defects in the LDLR pathway show a distinctive metabolomics profile. In conclusion, we show the potential of using metabolomics to segregate hypercholesterolemic subjects into different clusters, which may help in targeting genetic analysis