Lipoprotein apheresis: present and future uses

PURPOSE OF REVIEW

For the past 40 years, apheresis, in particular, lipoprotein apheresis, has been the therapy of choice to lower LDL-C for familial hypercholesterolemia patients with uncontrolled dyslipidemia and cardiovascular disease. With the advent of recent and future lipid-modifying agents and their ability to lower LDL-C, the question arises on what will be the future of lipoprotein apheresis.

RECENT FINDINGS

Lipoprotein apheresis lowers not only plasma levels of apolipoprotein B lipoproteins but also markers of vascular inflammation and blood rheology. Other vascular diseases, not necessarily associated with familial hypercholesterolemia, such as nephrotic syndrome and peripheral arterial disease have profited from lipoprotein apheresis therapy. In 2013, the Food and Drug Administration approved lipoprotein apheresis therapy for patients with focal segmental glomerulosclerosis. Since 2010, the German healthcare ministry has approved lipoprotein apheresis therapy for patients with an elevated lipoprotein(a) and ongoing cardiovascular disease irrespective of LDL-C levels.

SUMMARY

Recent and future lipid-modifying therapies will most likely reduce the practice of lipoprotein apheresis therapy for familial hypercholesterolemia patients. Future implications for lipoprotein apheresis will involve vascular diseases that are at present lacking clinically effective therapy, whereas acute and chronic reductions of lipids, vascular inflammation, and/or rheology may improve the clinical outcome.

The effects of affinity-purified anti-DNA antibodies from patients with systemic lupus erythematosus on the fluorescent antinuclear antibody assay using HEp-2 cells

The aim of this study was to clarify the effects of anti-dsDNA antibodies on the titer and the nuclear staining pattern(s) in a fluorescent antinuclear antibody (FANA) assay using HEp-2 cells. Anti-dsDNA derived from 14 patients with systemic lupus erythematosus (SLE) was individually affinity-purified. The anti-dsDNA titer of the purified anti-dsDNA solution was measured by radioimmunoassay (RIA) or by enzyme-linked immunosorbent assay (ELISA). In the FANA assay, the anti-dsDNA solution was diluted in a stepwise manner and its titer was expressed by the endpoint dilution. The nuclear staining pattern in the anti-dsDNA solution was examined at the 1:5 and 1:20 dilutions and at the endpoint dilution. The anti-dsDNA titers of the affinity-purified anti-dsDNA solution were high enough (13 to 126 IU/ml) to be measured by RIA. However, the antinuclear antibody (ANA) titers of this solution were relatively low: 1:20 to 1:320. In the study of nuclear staining the peripheral pattern was observed in nine of the 14 cases at a 1:5 dilution. However, at the endpoint dilution, all cases exhibited the homogeneous pattern. These findings indicate that in the FANA assay using HEp-2 cells, 1) although serum samples show high anti-dsDNA titers by RIA or by ELISA, the antibodies' direct contribution to ANA titers is limited, and 2) when samples reveal a homogeneous staining pattern at the endpoint dilution, this suggests the presence of anti-dsDNA.

Low-density lipoprotein apheresis for the treatment of refractory hyperlipidemia

The advent of treatment with 3-hydroxy-3-methylglutaryl coenzyme A inhibitors has meant that, with a combination of diet and drug therapy, adequate control of serum cholesterol concentrations can be achieved in most patients with hypercholesterolemia. However, some patients, primarily those with familial hypercholesterolemia (FH), may require additional therapy to lower their cholesterol levels. In recent years, low-density lipoprotein (LDL) apheresis has emerged as an effective method of treatment in these patients. The criteria for commencement of LDL apheresis are LDL cholesterol levels of 500 mg/dL or higher for homozygous FH patients, 300 mg/dL or higher for heterozygous FH patients in whom medical therapy has failed, and 200 mg/dL or higher for heterozygous FH patients with documented coronary disease and in whom medical therapy has failed. In addition to cholesterol lowering in patients with FH, other indications for LDL apheresis are emerging. These include its use in the treatment of graft vascular disease in patients receiving cardiac transplants as well as in the treatment of certain glomerulonephritides. This review examines the role of LDL apheresis in the management of lipid disorders and the evidence available to support its use in clinical practice.

Extracorporeal circuit heparinization in selective low density lipoprotein apheresis: changes in patient hemostasis and low molecular weight heparin benefit

Treatment by low density lipoprotein (LDL) apheresis using dextran sulfate columns (DSC) leads to hemostasis alterations with prolonged activated partial thromboplastin time (APTT) of more than 120 seconds. In order to explain this hypocoagulability, we studied hemostasis parameters both in patients and in the extracorporeal circulation (ECC). Hemostasis changes are first related to unfractionated heparin (UFH)--needed to avoid circuit coagulation--which leads to high residual heparinemia in the patient (more than 3 times the recommended level for therapeutic use). Second, the hypocoagulability is induced by a coagulation factor decrease (primarily factors V, VIII, and X) mainly due to an adsorption mechanism on dextran sulfate. Studies on samples from column inflow, outflow, and eluate confirm this mechanism. Low molecular weight heparin (LMWH) can be used in LDL apheresis on DSC without major changes in lipid removal or coagulation factors compared to UFH. The benefit of using LMWH is to reduce residual heparinemia into the therapeutic range.

Complement activation during low-density lipoprotein apheresis

Complement system activation was investigated in two girls with familial homozygous hypercholesterolemia undergoing two monthly sessions on LA15 or LA40 (Kaneka liposorber). We determined blood levels of C3c and C3a, leukocyte counts, and plasma levels of C3c and C3a in the extracorporeal circulation device at the start of the sessions and 15 and either 60 or 120 min into them. Sequential eluates were collected from LA40 at the end of the sessions (0.5M NaCl, 1M hydroxylamine). Anaphylatoxin C3a increased throughout, especially with LA40. As previously reported, C3a was trapped in the dextran column but was noticeably present in efferent plasma. Besides many proteins, nonnative complement fragments bearing C3a and C3d antigens were detected in almost all the eluates, suggesting possible in situ complement activation. Practically, complement activation induced by the first filter is a risk; long-term side effects may arise from this extracorporeal circulation device.

Treatment of refractory familial hypercholesterolemia by low-density lipoprotein apheresis using an automated dextran sulfate cellulose adsorption system. The Liposorber Study Group

A subgroup of patients with familial hypercholesterolemia (FH) respond inadequately to standard diet and drug therapy, and are therefore at high risk for the premature development or progression of coronary artery disease. This study evaluated low-density lipoprotein (LDL) cholesterol and lipoprotein (a) removal in a multicenter, controlled trial with a new LDL apheresis procedure (Liposorber LA-15 System). The study comprised patients with FH who had not responded adequately to diet and maximal drug therapy. There were 54 patients with heterozygous FH (45 randomized to treatment and 9 control subjects) and 10 with homozygous FH (all of whom received LDL apheresis). The study included three 6-week treatment phases and a 4-week rebound phase. Treatments were administered at 7- to 14-day intervals. Mean acute reductions in LDL cholesterol were 76% in heterozygous FH patients and 81% in homozygous ones. Time-averaged levels of LDL cholesterol were reduced 41% (243 to 143 mg/dl) in heterozygous FH patients and 53% (447 to 210 mg/dl) in homozygous ones. The substantial acute reduction of lipoprotein (a) (means: 65%, heterozygous FH; 68%, homozygous FH) has not been reported with other therapies. The Liposorber LA-15 System represents an important therapeutic option in FH patients who respond inadequately to diet and drug therapy.

Plasma exchange versus an affinity column for cholesterol reduction

The recent introduction of low-density lipoprotein (LDL)/very low-density lipoprotein (VLDL) selective-removal systems offers an alternative to plasma exchange (PE). For the last 10 years, we have treated a male homozygous hypercholesterolemia type IIA patient with PE using 5% normal serum albumin (NSA) replacement, PE using 6% hydroxyethyl starch (HES) replacement, single dextran sulfate cellulose bead affinity column (DSAC) (Kaneka LA-40), and double DSAC. This report compares the performance of these systems in cholesterol reduction (total, LDL+VLDL, and high-density lipoprotein [HDL] and their effect on the total protein, albumin, and hematocrit levels. The number of procedures and average volume of plasma treated using PE-NSA, PE-HES, 1-DSAC, and 2-DSAC were 113, 64, 15, 90 and 3,939, 3,270, 3,519, and 3,588 ml, respectively. The average pretreatment total cholesterol levels were baseline 864 mg/dL, PE-NSA 606 mg/dL, PE-HES 610 mg/dL, 1-DSAC 467 mg/dL, and 2-DSAC 395 mg/dL with plasma reductions of 59%, 57%, 47%, and 55%, respectively. Average LDL+VLDL plasma reductions were PE-NSA 58%, PE-HES 59% (N = 1), 1-DSAC 46%, and 2-DSAC 56%. Average HDL plasma reductions were PE-NSA 58%, PE-HES 69% (N = 1), 1-DSAC 5%, and 2-DSAC 17%. The average total cholesterol and LDL+VLDL reductions were comparable for both types of PE and the 2-DSAC system. The average HDL loss was 53% lower for the DSAC systems than for PE systems.(ABSTRACT TRUNCATED AT 250 WORDS)

Application of a new LDL apheresis system using two dextran sulfate cellulose columns in combination with an automatic column-regenerating unit and a blood cell separator

Extracorporeal procedures for selective removal of low-density lipoproteins have become a promising new approach for treatment of severe familial hypercholesterolemia. We tested efficacy and safety of a new LDL apheresis system by using two dextran sulfate cellulose adsorbents (Liposorber LA 15TM from Kanegafuchi) under the control of an automatic column-regenerating unit for continuous alternate adsorption and desorption. Plasma was taken from a continuous-flow blood cell separator (model IBM/Cobe 2997) allowing an extracorporeal circuit from one cubital vein to another. A 57-year-old male with drug-resistant heterozygous familial hypercholesterolemia accompanied by moderate hypertriglyceridemia and severe coronary artery disease has been treated every 2 weeks for 3 months so far. Treatment of 4-5 liters of plasma resulted in a mean decrease of total cholesterol from 355 to 111 mg/dl (9.20 to 2.88 mmol/l), of LDL cholesterol from 272 to 49 mg/dl (7.05 to 1.53 mmol/l), and of apolipoprotein B from 175 to 44 mg/dl. HDL cholesterol, apolipoprotein A-I, and other plasma proteins did not substantially change apart from hemodilution. No side effects were seen. This new technique of LDL apheresis represents a very effective and safe method for treatment of drug-resistant familial hypercholesterolemia without or with concomitant hypertriglyceridemia.

Lipoprotein particles in homozygous familial hypercholesterolemic patients treated with portacaval shunt and LDL apheresis

Lipoprotein particles containing apolipoproteins (Apo) were studied by enzyme-linked-immunosorbent assay in two homozygous familial hypercholesterolemic patients (1 male and 1 female) with portacaval shunts, and in controls. Total Apo B, total cholesterol and LDL cholesterol were increased in both patients while complex Apo B containing particles, Lp CIII: B, were not increased in these FH patients. The dextran-sulfate cellulose columns (Liposorber LA-40) had an excellent adsorption selectivity and adsorption capacity for lipoprotein particles containing Apo B and a minimum adsorption capacity in Apo AI and Apo AII-containing particles. This apheresis technique selectively depleted plasma of atherogenic Apo B-containing particles with a minimal loss of antiatherogenic Apo AI-containing particles.

Effect of continuous LDL apheresis with dextran-sulfate cellulose column system on a child with homozygous familial hypercholesterolemia

A new system for selective low density lipoprotein apheresis with an automated regenerating column using dextran-sulfate (DS) as ligand was evaluated for six months in a 13-year-old boy homozygous for familial hypercholesterolemia. Two columns each containing 150 ml of DS cellulose were alternately used after rinsing with a regenerating solution. The patient could well tolerate the volume in the system. The values of plasma total cholesterol decreased by 79.4 +/- 4.9% of the pretreatment levels after a total of 5l plasma apheresis, while those of high density lipoprotein cholesterol did not change. Although the values of CH50 decreased, no adverse reaction was seen during the period of treatment. It was concluded that the present apheresis system was highly efficacious and safe for children homozygous for the mutant LDL receptor gene.

Hypercholesterolemia and atherosclerosis: present and future therapy including LDL-apheresis

Atherosclerosis-induced coronary heart disease remains the major cause of death and disability in industrialized countries. Hypercholesterolemia is recognized as a causative factor in the development of atherosclerosis. While the lowering of cholesterol levels as a treatment goal has met with general agreement and acceptance, the preferred methods for doing so are still open to conjecture. This literature review discusses various factors in the hypercholesterolemia-atherosclerosis link and surveys a variety of treatment protocols including diet modification, drug therapy, surgical intervention, and plasmapheresis. Evidence is accumulating to prove that the ideal hypercholesterolemia therapy is one that reduces LDL levels while maintaining or increasing HDL levels. Because LDL-apheresis has this potential, this paper also reviews the various LDL-apheresis methods, including immunoadsorption, chemical affinity, and double-membrane filtration.