Long-term therapeutic efficacy of lipoprotein apheresis on circulating oxidative stress parameters--A comparison of two different apheresis techniques.

BACKGROUND: A chronic lipoprotein apheresis therapy leads to an expressed reduction in the incidence of cardiovascular events in high-risk patients. In addition to the elimination of atherogenic lipoproteins such as LDL and lipoprotein(a), an antioxidative effect of lipoprotein apheresis has been suspected. OBJECTIVES AND METHODS: We investigated long-term biochemical effects in sixteen patients undergoing lipoprotein apheresis - lipid filtration (LF, n = 7) or dextran sulfate adsorption (DSA, n = 9). Systemic oxidative stress markers (blood phagocyte chemiluminescence, levels of oxidized LDL and antioxLDL antibodies) were examined at the 1st, 40th and 80th apheresis sessions. RESULTS: In DSA patients, the 80th apheresis session was associated with significantly higher LDL cholesterol removal and lower HDL cholesterol deprivation as compared to LF patients. In contrast to LF patients, DSA patients showed a long-term progressive decrease in circulating oxidant generating activity as evaluated by whole blood chemiluminescence (p < 0.05). Moreover, a single LF apheresis session was associated with higher systemic generation of reactive oxygen species over time. CONCLUSION: Compared to LF, long-term DSA apheresis is associated with a gradual reduction of circulating oxidative burden and may be considered a beneficial molecular mechanism of this technique.

Glucose-dependent leukocyte activation in patients with type 2 diabetes mellitus, familial combined hyperlipidemia and healthy controls.

BACKGROUND: Leukocyte activation has been associated with vascular complications in type 2 diabetes mellitus (T2DM). Hyperglycemia may be involved in this leukocyte activation. Our aim was to investigate the role of elevated glucose concentrations on leukocyte activation in patients with a wide range of insulin sensitivity. METHODS: Leukocyte activation was determined after ingestion of 75 gram glucose in subjects with T2DM, familial combined hyperlipidemia (FCH) and healthy controls. Leukocyte activation markers were measured by flow cytometry. Postprandial changes were calculated as the area under the curve (AUC), and the incremental area under the curve corrected for baseline values (dAUC). RESULTS: 51 Subjects (20 T2DM, 17 FCH and 14 controls) were included. Fasting neutrophil CD66b expression and CD66b-AUC were respectively 36% and 39% higher in T2DM patients than in controls (p=0.004 and p=0.003). Fasting neutrophil CD66b expression correlated positively with glucose-AUC (Spearman's rho 0.481, p<0.001) and HbA1c (rho 0.433, p=0.002). Although fasting monocyte CD11b expression was not significantly different between subjects, monocyte CD11b-AUC was 26% higher in T2DM than in controls (p=0.006). Similar trends were observed for FCH patients. Monocyte CD11b-dAUC correlated positively with glucose-AUC (rho 0.322, p=0.022) and HbA1c (rho 0.319, p=0.023). CONCLUSIONS: These data suggest that both acute and chronic hyperglycemia, associated with insulin resistance as seen in T2DM and FCH, are involved in the increased fasting and postprandial leukocyte activation observed in these conditions.

Endothelial activation, inflammation and premature atherosclerosis in children with familial dyslipidemia.

OBJECTIVES: Prospective studies demonstrated an increased cardiovascular risk in subjects with high levels of either the endothelial-platelet activation marker P-selectin or high-sensitivity C-reactive protein (hs-CRP). Both children with heterozygous familial hypercholesterolemia (FH) and those with familial combined hyperlipidemia (FCHL) are prone to premature atherosclerosis. Our objective was to investigate in children with either FH or FCHL whether P-selectin and hs-CRP contribute to carotid intima-media thickness (IMT), along with increased plasma lipid levels. METHODS: Carotid IMT, serum lipids and soluble P-selectin and hs-CRP levels were measured in 88 children (mean age 10.5+/-4.3 years) including 44 dyslipidemic children (25 with FH and 19 with FCHL) and 44 non-dyslipidemic controls. RESULTS: Carotid IMT was significantly higher among dyslipidemic than in control children (0.46+/-0.06mm vs 0.43+/-0.06mm, p=0.003) and serum P-selectin levels as well [129(50-254)ng/mL vs 50(24.5-130)ng/mL, p<0.001]. FH but not FCHL children had higher hs-CRP levels than controls [0.7(0.01-6.9)mg/L vs 0.3(0.1-1.2)mg/L, p=0.006]. In the entire sample of dyslipidemic children, carotid IMT was positively associated with soluble P-selectin levels (rho=0.30, p=0.049), but not with hs-CRP. The association between P-selectin and carotid IMT was independent from confounders, including plasma lipid levels. CONCLUSION: Endothelial-platelet activation, more than low-grade systemic inflammation, correlates with premature atherosclerosis among children with familial dyslipidemia, this association being independent from plasma lipid levels.

Autoantibody titers against OxLDL are correlated with Achilles tendon thickness in patients with familial hypercholesterolemia.

Achilles tendon xanthomas are associated with increased cardiovascular risk in patients with familial hypercholesterolemia (FH). Oxidized low density lipoprotein (OxLDL), the antibodies against OxLDL, and the LDL-associated phospholipase A(2) (Lp-PLA(2)) may play important roles in atherogenesis. We investigated the possible association between plasma levels of OxLDL, Lp-PLA(2) activity, and autoantibody titers against various types of mildly OxLDL with Achilles tendon thickness (ATT). ATT was determined by sonography in 80 unrelated heterozygous FH patients. Three different types of mildly OxLDL were prepared: OxLDL(L), OxLDL(P), and OxLDL(D), at the end of the lag, propagation, and decomposition phases of oxidation, respectively. Similar types of OxLDL were also prepared after inactivation of the LDL-associated Lp-PLA(2). These types were denoted OxLDL(-)(L), OxLDL(-)(P), and OxLDL(-)(D). FH patients exhibited significantly higher plasma OxLDL levels and serum IgG titers against OxLDL(P) and OxLDL(D) compared with 40 normolipidemic apparently healthy controls. ATT values were positively correlated with autoantibody titers against OxLDL(P) and OxLDL(D); however, in multiple regression analysis, ATT was independently associated only with the autoantibody titers against OxLDL(D). We conclude that the IgG autoantibody titers against OxLDL(D) but not OxLDL or Lp-PLA(2) may play an important role in the pathogenesis of Achilles tendon xanthomas in FH patients.

Changes of autoantibodies against oxidatively modified low density lipoproteins during long-term LDL-apheresis.

The oxidation of low-density lipoproteins (LDL) is considered a key event in the initiation of atherosclerosis. The aim of this study was to follow-up the biological marker of in vivo LDL oxidation (oxidatively modified LDL autoantibody titres) during long-term LDL-apheresis treatment. A patient suffering from severe combined hyperlipidaemia underwent LDL-apheresis biweekly and was followed for two years. The significant reduction of baseline total cholesterol (58%), total triglycerides (80%), LDL-cholesterol (48%), apoprotein B (50%) and apolipoprotein (a) (61%) may be considered as a good response to the treatment. The titre of autoantibodies (IgG) against oxidatively modified LDL (malondialdehyde-derived LDL) was followed throughout the study and showed dynamic changes. The measured values were multiple compared as mean+/-SD over each semester of apheresis application: I semester 70.0+/-8.3 U/ml, n = 12; II semester 58.0+/-13.8 U/ml, n = 12; III semester 37.6+/-6.0 U/ml, n=12; IV semester 34.3+/-7.0 U/ml, n = 12; ANOVA: I vs. II semester p<0.083, II vs. III semester p<0.00053, III vs. IV semester p<0.248. In parallel to the changes in this biochemical parameter, regression of numerous xanthomas was clinically observed. In spite of this, the presence of oxidised-LDL (oxLDL) antibodies was enhanced in comparison to antibody titre detected in a group of age-matched normolipaemic healthy controls (n = 15; 19.4+/-8.6; p<0.01). Classical lipoprotein parameters were correlated with the titre of autoantibodies against oxLDL and showed low correlation coefficients: total cholesterol vs. oxLDLab, r = 0.36; triglycerides vs. oxLDLab, r = 0.43; LDL cholesterol vs. oxLDLab, r = 0.14; HDL cholesterol vs. oxLDLab, r = -0.33; apo B vs. oxLDLab, r = 0.25; apo (a) vs. oxLDLab, r = -0.05. Our study showed an additional benefit of LDL-apheresis therapy. The production of autoantibodies against oxLDL was reduced during the treatment, indicating a lower level of the atherogenic antigen.