Single Low-Density Lipoprotein Apheresis Does Not Improve Vascular Endothelial Function in Chronically Treated Hypercholesterolemic Patients

Antioxidant action of vitamin E in vivo as assessed from its reaction products with multiple biological oxidants

Vitamin E acts as essential antioxidant against detrimental oxidation of biological molecules induced by multiple reactive species. To gain more insight into the physiological role of vitamin E, the levels of its oxidation products in humans under normal and pathological conditions were compared. α-Tocopherol quinone (α-TQ) and 5-nitro-γ-tocopherol (5-NgT) were focused. α-TQ is produced by multiple oxidants including oxygen radicals, peroxynitrite, hypochlorite, singlet oxygen, and ozone, while 5-NgT is produced by nitrogen dioxide radical derived from peroxynitrite and the reaction of nitrite and hypochlorite. The reported concentrations of α-TQ and 5-NgT in healthy human plasma are highly variable ranging from 15 to 360 and 4 to 170 nM, respectively. In general, the molar ratio 5-NgT/γ-tocopherol was higher than the ratio α-TQ/α-tocopherol. Both absolute concentrations of α-TQ and 5-NgT and the molar ratios to the parent tocopherols were elevated significantly in the plasma of patients with various diseases compared with healthy subjects except neurological diseases. The molar ratios of the products to the respective parent compounds decreased in the order of 5-NgT/γ-tocopherol > α-TQ/α-tocopherol > hydroxyoctadecadienoate/linoleate > 3-nitrotyrosine/tyrosine > isoprostane/arachidonate. The molar ratios of nitrated products to the respective parent compounds in human plasma are approximately 10^-2 for 5-NgT and 10^-5 for 3-nitrotyrosine, nitro-oleic acid, and 8-nitroguaine. These data indicate that vitamin E acts as an important physiological antioxidant and that α-TQ and 5-NgT represent biomarker for oxidative stress and nitrative stress respectively.

Lipoprotein apheresis in the treatment of dyslipidaemia - the Czech Republic experience

In 1984, we started using therapeutic plasmapheresis (plasma exchange) as a method of extracorporeal lipoprotein elimination for the treatment of hypercholesterolemic patients. We evaluated the results of long-term therapy in 14 patients, 8 men and 6 women. The average age was 55.6+/-13.2 (range 28-70), median 59.5 years. 14 patients were diagnosed with familial hypercholesterolemia (FH): 5 homozygous, 9 heterozygous. Ten patients in the group were treated using immunoadsorption lipoprotein apheresis and 4 using hemorheopheresis. Immunoapheretic interventions decreased LDL-cholesterol (82+/-1 %), ApoB (73+/-13 %) and even Lp(a) by 82+/-19 %, respectively. Selected non-invasive methods are important for long-term and repeated follow-up. Carotid intima-media thickness showed improvement or stagnation in 75 % of the patients. Biomarkers of endothelial dysfunction such as endoglin (in the control group: 3.85+/-1.25 microg/l, in lipoprotein apheresis-treated hypercholesterolemic individuals 5.74+/-1.47 microg/l), CD40 ligand (before lipoprotein apheresis: 6498+/-2529 ng/l, after lipoprotein apheresis: 4057+/-2560 ng/l) and neopterin (before lipoprotein apheresis: 5.7+/-1.1 nmol/l, after lipoprotein apheresis: 5.5+/-1.3 nmol/l) related to the course of atherosclerosis, but did not reflect the actual activity of the disease nor facilitate the prediction or planning of therapy. Hemorheopheresis may improve blood flow in microcirculation in familial hypercholesterolemia and also in some other microcirculation disorders via significantly decreased activity of thrombomodulin (p<0.0001), tissue factor (p<0.0001), aggregation of thrombocytes (p<0.0001) and plasma and whole blood viscosity (p<0.0001). In conclusion, lipoprotein apheresis and hemorheopheresis substantially lowered LDL-cholesterol in severe hypercholesterolemia. Our experience with long-term therapy also shows good tolerance and a small number of complications (6.26 % non-serious clinical complications).

Antioxidant defense system in familial hypercholesterolemia and the effects of lipoprotein apheresis

Oxidative stress is thought to play an important role in the pathogenesis of disorders associated with atherosclerosis. Alpha-tocopherol is considered to be an effective lipophilic antioxidant, which protects lipid membranes against peroxidation and thus prevents cell damage by reaction with free radicals. However, measurement of alpha-tocopherol concentration in serum does not reflect the content of α-tocopherol in membranes whereas erythrocyte alpha-tocopherol may be good indicator of antioxidative status. Therefore a simple isocratic reversed phase HPLC method has been developed and validated for the determination of alpha-tocopherol in human erythrocytes in a clinical setting. The content of alpha-tocopherol in human erythrocyte membrane and lipoperoxidation were studied in patients with severe hypercholesterolemia treated by lipoprotein apheresis. The group of hypercholesterolemic patients (n = 14) treated by lipoprotein apheresis was compared to healthy adult normolipidemic controls. After lipoprotein apheresis, the content of in membrane alpha-tocopherol did not change significantly despite decreased tocopherol in serum and lipoprotein fractions. We observed significantly decreased lipoperoxidation as revealed by serum TBARS, representing end products of lipid peroxidation, which increased from third day afterwards and remained significantly higher in comparison to controls until the next LDL-apheresis. We conclude that aggressive lipid lowering procedure with lipoprotein apheresis was associated with favorable transient decrease of lipoperoxidation. Simultaneously the cell membrane bound antioxidative defense mechanisms as reflected by the content of alpha-tocopherol in human erythrocyte membrane where not depressed in spite of its decreased plasma lipid carrier. Another variables involved remain to be investigated.

Two Patients with Familial Hypercholesterolemia Who Were Successfully Weaned from Low-density Lipoprotein Apheresis after Treatment with Evolocumab

Two elderly patients (a 76-year-old man and a 75-year-old woman), who had been previously diagnosed with familial hypercholesterolemia (at 58 and 48 years of age, respectively) underwent long-term treatment with oral therapy and low-density lipoprotein (LDL) apheresis. As their LDL cholesterol levels remained high (>150 mg/dL and >120 mg/dL, respectively) and their familial hypercholesterolemia was complicated with angina pectoris, we added evolocumab to their prescription. Thereafter, their LDL cholesterol levels decreased rapidly, and the patients were successfully weaned from LDL apheresis. Evolocumab therapy should thus be considered when LDL apheresis cannot achieve the target LDL cholesterol levels, though the prognosis of such treatment remains unclear.