Erythrocyte-bound apolipoprotein B in atherosclerosis and mortality.

BACKGROUND: The binding of apolipoprotein (apo) B-containing lipoproteins to circulating erythrocytes (ery-apoB) is associated with a decreased prevalence of atherosclerosis. In this study, we evaluated ery-apoB as a possible prognostic factor in cardiovascular events and all-cause mortality, in a prospective cohort study. MATERIALS AND METHODS: Ery-apoB was measured by flow cytometry in subjects with and without cardiovascular disease (CVD). The primary endpoint was the cardiovascular event rate. Secondary endpoints were all-cause mortality and the combined endpoint of all-cause mortality and cardiovascular events (any event rate). A Cox regression analysis with univariate and multivariate analyses and Kaplan-Meier survival analysis was performed. RESULTS: Follow-up data were available of 384 subjects. Subjects were divided according to high (> 2·0 au, n = 60), intermediate (0·2-2·0 au, n = 274) or low (< 0·2 au, n = 50) ery-apoB. Median follow-up was 1767 days (IQR 1564-2001). In univariate analysis, low ery-apoB was associated with increased all-cause mortality [HR 9·9 (1·2-79·0), P = 0·031] and any event rate [HR 3·4 (95% CI 1·3-8·7), P = 0·012]. In a Cox regression analysis, only a history of CVD was significantly associated with any event rate [HR 3·6 (1·6-8·0), P = 0·002], while low ery-apoB showed a trend [HR 2·4 (0·9-6·4), P = 0·07]. In a subgroup analysis, in subjects with a history of CVD, ery-apoB was significantly associated with all-cause mortality (log rank P = 0·021) and any event rate (log rank P = 0·009). CONCLUSIONS: Low ery-apoB is associated with increased mortality and cardiovascular risk, especially in patients with a prior history of CVD. These subjects may benefit from more aggressive secondary prevention treatment.

Differential complement activation pathways promote C3b deposition on native and acetylated LDL thereby inducing lipoprotein binding to the complement receptor 1.

Lipoproteins can induce complement activation resulting in opsonization and binding of these complexes to complement receptors. We investigated the binding of opsonized native LDL and acetylated LDL (acLDL) to the complement receptor 1 (CR1). Binding of complement factors C3b, IgM, C1q, mannose-binding lectin (MBL), and properdin to LDL and acLDL were investigated by ELISA. Subsequent binding of opsonized LDL and acLDL to CR1 on CR1-transfected Chinese Hamster Ovarian cells (CHO-CR1) was tested by flow cytometry. Both native LDL and acLDL induced complement activation with subsequent C3b opsonization upon incubation with normal human serum. Opsonized LDL and acLDL bound to CR1. Binding to CHO-CR1 was reduced by EDTA, whereas MgEGTA only reduced the binding of opsonized LDL, but not of acLDL suggesting involvement of the alternative pathway in the binding of acLDL to CR1. In vitro incubations showed that LDL bound C1q, whereas acLDL bound to C1q, IgM, and properdin. MBL did neither bind to LDL nor to acLDL. The relevance of these findings was demonstrated by the fact that ex vivo up-regulation of CR1 on leukocytes was accompanied by a concomitant increased binding of apolipoprotein B-containing lipoproteins to leukocytes without changes in LDL-receptor expression. In conclusion, CR1 is able to bind opsonized native LDL and acLDL. Binding of LDL to CR1 is mediated via the classical pathway, whereas binding of acLDL is mediated via both the classical and alternative pathways. Binding of lipoproteins to CR1 may be of clinical relevance due to the ubiquitous cellular distribution of CR1.

Diagnosing metabolic syndrome in craniopharyngioma patients: body composition versus BMI.

OBJECTIVE: Craniopharyngioma patients often have poor metabolic profiles due to hypothalamic-pituitary damage. Previously, using BMI as obesity marker, the occurrence of the metabolic syndrome in these patients was estimated at 46%. Our aim was to determine if dual X-ray absorptiometry (DXA) scan in evaluation of obesity and metabolic syndrome would be superior. DESIGN: Retrospective study of craniopharyngioma patients for whom DXA scan results were available. METHODS: BMI, fat percentage and fat mass index were used to evaluate obesity and as components for obesity in metabolic syndrome. RESULTS: Ninety-five craniopharyngioma patients were included (51% female, 49% childhood-onset disease). Metabolic syndrome occurred in 34-53 (45-51%) subjects (depending on the definition of obesity, although all definitions occurred in higher frequency than in the general population). Metabolic syndrome frequency was higher if obesity was defined by fat percentage (52 vs 42%) or fat mass index (51 vs 43%) compared to BMI. Misclassification appeared in 9% (fat percentage vs BMI) and 7% (fat mass index vs BMI) for metabolic syndrome and 29 and 13% for obesity itself, respectively. For metabolic syndrome, almost perfect agreement was found for BMI compared with fat percentage or fat mass index. For obesity, agreement was fair to moderate (BMI vs fat percentage). CONCLUSION: Using BMI to evaluate obesity underestimates the true prevalence of metabolic syndrome in patients with craniopharyngioma. Furthermore, fat percentage contributes to a better evaluation of obesity than BMI. The contribution of DXA scan might be limited for identification of the metabolic syndrome.

Coronary leukocyte activation in relation to progression of coronary artery disease.

Leukocyte activation has been linked to atherogenesis, but there is little in vivo evidence for its role in the progression of atherosclerosis. We evaluated the predictive value for progression of coronary artery disease (CAD) of leukocyte activation markers in the coronary circulation. Monocyte and neutrophil CD11b, neutrophil CD66b expression and intracellular neutrophil myeloperoxidase (MPO) in the coronary arteries were determined by flow cytometry in patients undergoing coronary angiography. The primary outcome included fatal and nonfatal myocardial infarction or arterial vascular intervention due to unstable angina pectoris. In total 99 subjects who were included, 70 had CAD at inclusion (26 patients had single-vessel disease, 18 patients had twovessel disease and 26 patients had three-vessel disease). The median follow-up duration was 2242 days (interquartile range: 2142-2358). During follow-up, 13 patients (13%) developed progression of CAD. Monocyte CD11b, neutrophil CD11b and CD66b expression and intracellular MPO measured in blood obtained from the coronary arteries were not associated with the progression of CAD. These data indicate that coronary monocyte CD11b, neutrophil CD11b and CD66b expression and intracellular MPO do not predict the risk of progression of CAD.