Lipoprotein apheresis in the management of severe hypercholesterolemia and hyperlipoproteinemia(a)-The Portuguese experience.

BACKGROUND: Low-density lipoprotein cholesterol (LDL-C) and lipoprotein(a) (Lp(a)) are established causal risk factors for cardiovascular disease (CVD). Lipoprotein apheresis is often required for treatment of patients with a high risk for CVD due to hypercholesterolemia and/or hyperlipoproteinemia(a). AIM: To describe our experience with lipoprotein apheresis in patients with severe hypercholesterolemia or with hyperlipoproteinemia(a). METHODS: We retrospectively investigated patients treated with Lipoprotein apheresis using direct adsorption of lipoproteins (DALI) technique, between December 2008 and March 2018, in our center. Adverse events, acute and long term reductions in lipid parameters were analyzed. RESULTS: Between December 2008 and March 2018, a total of 950 treatments were performed in five patients, four with heterozygous familial hypercholesterolemia (HeFH), all on maximally tolerated cholesterol-lowering drug therapy and in one patient with hyperlipoproteinemia(a) and progressive CVD. In the four patients with HeFH we obtained mean acute reductions in LDL-C and non-high-density lipoprotein cholesterol (non-HDL-C) of 62.0 ± 7.8% and 60.4 ± 6.8%, respectively. Regarding long-term efficacy we achieved a mean reduction of 43.1% in LDL-C and of 41.2% in non-HDL-C. In the patient with hyperlipoproteinemia(a) we attained mean acute reductions of 60.4 ± 6.4% in Lp(a) and of 75.4 ± 7.3% in LDL-C per session and long term reductions in Lp(a) and LDL-C of 67.4% and 40.5%, respectively. Adverse events were recorded in only 1.2% of treatments. CONCLUSION: Lipoprotein apheresis is an efficient and safe treatment in severely hypercholesterolemic patients who are refractory to conservative lipid-lowering therapy or with hyperlipoproteinemia(a) and progressive CVD.

Novel polymorphisms associated with hyperalphalipoproteinemia and apparent cardioprotection.

BACKGROUND: Hyperalphalipoproteinemia (HALP) is inversely correlated with coronary heart disease (CHD) although genetic variants associated with high serum levels of high-density lipoprotein cholesterol (HDL-C) have not been shown to be cardioprotective. OBJECTIVE: The objective of the study was to uncover novel genetic variants associated with HALP and possibly with reduced risk of CHD. METHODS: Exome sequencing data, HDL-C, and triglyceride levels were analyzed in 1645 subjects. They included the University of Maryland outpatients with high HDL-C (n = 12), Cardiovascular Health Study (n = 210), Jackson Heart Study (n = 402), Multi-Ethnic Study of Atherosclerosis (n = 404), Framingham Heart Study (n = 463), and Old Order Amish (n = 154). RESULTS: Novel nonsynonymous single-nucleotide polymorphisms (nsSNPs) were identified in men and women with primary HALP (mean HDL-C, 145 ± 30 mg/dL). Using PolyPhen-2 and Combined Annotation Dependent Depletion to estimate the predictive effect of each nsSNP on the gene product, rare, deleterious polymorphisms in UGT1A3, PLLP, PLEKHH1, ANK2, DIS3L, ACACB, and LRP4 were identified in 16 subjects with HALP but not in any tested subject with low HDL-C (<40 mg/dL). In addition, a single novel polymorphism, rs376849274, was found in OSBPL1A. The majority of these candidate genes have been implicated in fat and lipid metabolism, and none of these subjects has a history of CHD despite 75% of subjects having risk factors for CHD. Overall, the probability of finding these nsSNPs in a non-high HDL-C population ranges from 1 × 10-17 to 1 × 10-25. CONCLUSION: Novel functional polymorphisms in 8 candidate genes are associated with HALP in the absence of CHD. Future study is required to examine the extent to which these genes may affect HDL function and serve as potential therapeutic targets for CHD risk reduction.

Experimental models of hyperlipoproteinemia and atherosclerosis.

The first experimental model of atherosclerosis (in rabbits) is more than hundred years old. Several animal species have been used to produce hyperlipoproteinemia and possible atherosclerosis. The gene manipulation produced the most used models recently. This review acknowledges the extensive study of atherosclerotic changes in experimental models of hyperlipoproteinemia and atherosclerosis to come to light thus far and the purpose here is not only to summarize the published data but also to try to add some details of our experience in using these models. In addition to rabbit (the old but also improved model by reno-vascular hypertension) dog, birds, pig, hamster, mice, rat and non-human primate's animal models are described. The gene manipulation produced the most used models two decades ago. Germline genetically engineered (without apoE or LDL receptor genes) animals have become the most used models producing atherosclerotic changes in the aorta. Recent new models also producing atherosclerotic changes but without germline genetic manipulation are also described.

Serum amyloid A regulates monopoiesis in hyperlipidemic Ldlr(-/-) mice.

We previously showed that feeding a Western-type diet (WTD) to Ldlr(-/-) mice lacking serum amyloid A (SAA) (Saa(-/-) Ldlr(-/-) mice), the level of total blood monocytes was higher than in Ldlr(-/-) mice. In this investigation we demonstrate that higher levels of bone marrow monocytes and macrophage-dendritic cell progenitor (MDP) cells were found in WTD-fed Saa(-/-) Ldlr(-/-) mice compared to Ldlr(-/-) mice and lower levels of GMP cells and CMP cells in Ldlr(-/-) mice. These data indicate that SAA regulates the level of bone marrow monocytes and their myeloid progenitors in hyperlipidemic Ldlr(-/-) mice.

Formation of fenestrae in murine liver sinusoids depends on plasmalemma vesicle-associated protein and is required for lipoprotein passage.

Liver sinusoidal endothelial cells (LSEC) are characterized by the presence of fenestrations that are not bridged by a diaphragm. The molecular mechanisms that control the formation of the fenestrations are largely unclear. Here we report that mice, which are deficient in plasmalemma vesicle-associated protein (PLVAP), develop a distinct phenotype that is caused by the lack of sinusoidal fenestrations. Fenestrations with a diaphragm were not observed in mouse LSEC at three weeks of age, but were present during embryonic life starting from embryonic day 12.5. PLVAP was expressed in LSEC of wild-type mice, but not in that of Plvap-deficient littermates. Plvap(-/-) LSEC showed a pronounced and highly significant reduction in the number of fenestrations, a finding, which was seen both by transmission and scanning electron microscopy. The lack of fenestrations was associated with an impaired passage of macromolecules such as FITC-dextran and quantum dot nanoparticles from the sinusoidal lumen into Disse's space. Plvap-deficient mice suffered from a pronounced hyperlipoproteinemia as evidenced by milky plasma and the presence of lipid granules that occluded kidney and liver capillaries. By NMR spectroscopy of plasma, the nature of hyperlipoproteinemia was identified as massive accumulation of chylomicron remnants. Plasma levels of low density lipoproteins (LDL) were also significantly increased as were those of cholesterol and triglycerides. In contrast, plasma levels of high density lipoproteins (HDL), albumin and total protein were reduced. At around three weeks of life, Plvap-deficient livers developed extensive multivesicular steatosis, steatohepatitis, and fibrosis. PLVAP is critically required for the formation of fenestrations in LSEC. Lack of fenestrations caused by PLVAP deficiency substantially impairs the passage of chylomicron remnants between liver sinusoids and hepatocytes, and finally leads to liver damage.

Cognitive impairment and polidistrectual atherosclerotic disease in chylomicronemia syndrome: a case report.

A case of chylomicronemia syndrome is reported in a 72-year-old male with distinctive features of chronic pancreatic damage, severe hypertriglyceridemia, polidistrectual atherosclerosis and premature cognitive impairment. Although the patient had a positive history for recurrent episodes of pancreatitis the characteristic lesions of the hyperchylomicronemia syndrome, such as eruptive xanthomas and lipemia retinalis, were not present and splenomegaly could not be documented due to a previous post-traumatic splenectomy. Based on clinical phenotype, an apolipoprotein C-II deficiency was excluded by a fresh plasma infusion test, in which clarification of the patient plasma was not obtained. The absence of changes in the lipoprotein electrophoretic plasma after heparin infusion can be secondary to a lipoprotein lipase deficiency, a rare genetic disorder with an incidence of one per million. In relation to the resistance to diet and drugs, plasma exchange therapy was performed. After 3 years of this treatment there was no significant progression of atherosclerosis.

A polygenic basis for four classical Fredrickson hyperlipoproteinemia phenotypes that are characterized by hypertriglyceridemia.

Numerous single nucleotide polymorphisms (SNPs) have been found in recent genome wide association studies (GWAS) to be associated with subtle plasma triglyceride (TG) variation in normolipidemic subjects. However, since these GWAS did not specifically evaluate patients with rare disorders of lipoprotein metabolism--'hyperlipoproteinemia' (HLP)--it remains largely unresolved whether any of these SNP determinants of modest physiological changes in TG are necessarily also determinants of most HLP phenotypes. To address this question, we evaluated 28 TG-associated SNPs from GWAS in 386 unrelated adult patients with one of five Fredrickson phenotypes (HLP types 2A, 2B, 3, 4 and 5) and 242 matched normolipidemic controls. We found that several SNPs associated with TG in normolipidemic samples, including APOA5 p.S19W and -1131T>C, TRIB1 rs17321515, TBL2 rs17145738, GCKR rs780094, GALNT2 rs4846914 and ANGPTL3 rs12130333, were significantly associated with HLP types 2B, 3, 4 and 5. The findings indicate that: (i) the TG-associated Fredrickson HLP types 2B, 3, 4 and 5 are polygenic traits; (ii) these Fredrickson HLP types share numerous genetic determinants among themselves; and (iii) genetic determinants of modest TG variation in normolipidemic population samples also underlie--to an apparently even greater degree--susceptibility to these rare HLP phenotypes. Thus, the TG-associated Fredrickson HLP types 2B, 3, 4 and 5, although historically considered to be distinct are actually complex traits sharing among them several common genetic determinants seen in GWAS of normolipidemic population samples.

Plasma lipoproteins: genetic influences and clinical implications.

Susceptibility to the growing global public health problem of cardiovascular disease is associated with levels of plasma lipids and lipoproteins. Several experimental strategies have helped us to clarify the genetic architecture of these complex traits, including classical studies of monogenic dyslipidaemias, resequencing, phenomic analysis and, more recently, genome-wide association studies and analysis of metabolic networks. The genetic basis of plasma lipoprotein levels can now be modelled as a mosaic of contributions from multiple DNA sequence variants, both rare and common, with varying effect sizes. In addition to filling gaps in our understanding of plasma lipoprotein metabolism, the recent genetic advances will improve our ability to classify, diagnose and treat dyslipidaemias.

The two novel CETP mutations Gln87X and Gln165X in a compound heterozygous state are associated with marked hyperalphalipoproteinemia and absence of significant coronary artery disease.

High levels of high-density lipoprotein cholesterol (HDL-C) occur with cholesteryl ester transfer protein (CETP) deficiency. However, the extent to which CETP deficiency states may be associated with protection against coronary artery disease (CAD) has been controversial. We evaluated a Greek pedigree with high levels of HDL-C and no history of premature CAD. The proband, a 45-year-old male with an HDL-C of 194 mg/dl with absent CETP activity, was heterozygous for two novel CETP mutations (Q87X and Q165X). A 64-slice multidetector CT scan revealed minimal (<10%) narrowing of the proximal left anterior descending artery without any other evidence of coronary atherosclerosis. In contrast to previous studies, these data suggest that complete CETP deficiency does not promote premature atherosclerosis. However, it remains unclear as to whether the relative lack of coronary atherosclerosis was the direct consequence of CETP deficiency and/or the lack of traditional CAD risk factors.

Hyperlipoproteinemia impairs endothelium-dependent vasodilation.

Atherogenic lipoproteins can cause endothelial dysfunction in the initial stage of atherogenesis. In our study we examined 134 patients with defined hyperlipoproteinemia (non-HDL cholesterol>4.1 mmol/l or triglycerides>2.5 mmol/l or taking any of lipid lowering drugs)--94 men and 40 women. The subgroup of controls of comparable age contained 54 normolipidemic individuals--30 men and 24 women. Patients with hyperlipoproteinemia revealed significantly lower ability of endothelium-dependent flow-mediated vasodilation (EDV) measured on brachial artery (4.13+/-3.07 vs. 5.41+/-3.82 %; p=0.032) and higher carotid intima media thickness than normolipidemic controls (0.68+/-0.22 vs. 0.58+/-0.15 mm; p=0.005). In regression analysis, EDV correlated significantly with plasma concentrations of oxLDL (p<0.05) HDL-cholesterol (p<0.05), Apo A1 (p<0.05), ATI (p<0.01) and non-HDL cholesterol (p<0.05). Patients with hyperlipoproteinemia showed higher plasma levels of oxLDL (65.77+/-9.54 vs. 56.49+/-7.80 U/l; p=0.015), malondialdehyde (0.89+/-0.09 vs. 0.73+/-0.08 micromol/l; p=0.010) and nitrites/nitrates (20.42+/-4.88 vs. 16.37+/-4.44 micromol/l; p=0.018) indicating possible higher long-term oxidative stress in these patients.

Postprandial lipemia and cardiovascular disease.

Postprandial lipemia, characterized by a rise in triglyceride-rich lipoproteins after eating, is a dynamic, nonsteady-state condition in which humans spend the majority of time. There are several lines of evidence suggesting that postprandial lipemia increases risk of atherogenesis. Clinical data show a correlation between postprandial lipoproteins and the presence/progression of coronary artery disease and carotid intimal thickness. Mechanistic studies demonstrate that triglyceride-rich lipoprotein remnants may have adverse effects on endothelium and can penetrate into the subendothelial space. Exchange of core lipids between postprandial lipoproteins and low-density lipoprotein (LDL)/high-density lipoprotein (HDL) is increased during prolonged lipemia, resulting in small, dense LDL particles and reduced HDL cholesterol levels. Hemostatic variables, including clotting factors, platelet reactivity, and monocyte cytokine expression, may be increased during postprandial lipemia. Collectively, these data suggest that assessment and treatment of atherosclerosis should include parameters related to postprandial lipemia.

[Indirect relation between intimo-medial thickness of the carotid artery and vasodilation of the popliteal artery]. / Neprímý vztah mezi sírakou intimomediální vrstvy arteria carotis a schopností dilatace arteria poplitea.

BACKGROUND: Intima-media thickness of the common carotid artery (IMT ACC) and flow-mediated vasodilatation (FMD) of the brachial artery is considered an early marker of atherosclerosis. This study was undertaken to elucidate whether endothelial dysfunction in the popliteal artery, pronoun to atherosclerosis, is related to IMT ACC. METHODS AND RESULTS: Twenty-nine control subjects, 29 asymptomatic patients with hyperlipoproteinemia (without therapy) and 26 patients with coronary artery disease were examined. Using ultrasound with a linear-array probe (7.5 MHz), we measured IMT ACC and diameter of the popliteal artery (PA) at rest and during reactive hyperaemia after release of 5-minute arterial occlusion. In control subjects we found thicker IMT ACC and greater FMD than did the patients (p<0.001, ANOVA test). A significant negative correlation between the IMT ACC and percent FMD was found in all of the subjects (p<0.001). On multiple regression analysis, percent FMD showed a significant negative correlation with the IMT ACC, total cholesterol, triacylglyceroles, body mass index, age, and diastolic blood pressure. CONCLUSION: We found significant negative correlation between IMT common carotid artery and FMD popliteal artery.

[Treatment of dyslipoproteinemia by systemic enzyme therapy in experimental glomerulonephritis]. / Korrektsiia dislipoproteidemii posredstvom sistemnoi énzimoterapii pri éksperimental'nom glomerulonefrite.

Patients with chronic glomerulonephritis (CG) develop disturbances of lipid blood spectrum leading to additional damage to renal structure. The existent methods of pathogenetic therapy have no effect on lipid imbalance. Recently, many autoimmune diseases have been treated with systemic enzyme therapy (SET). The authors studied SET effect in disturbed lipid metabolism in experimental glomerulonephritis. Experimental animals showed morphological and biochemical changes similar to those in CG of man. SET reduced renal tissue damage and symptoms of dyslipoproteinemia.

[Dilatation of the popliteal artery in hyperemia and intimal-medial thickness of the carotid artery in hyperlipoproteinemia, ischemic heart disease and in healthy individuals]. / Schopnost dilatace podkolenní tepny pri hyperemii a intimomediální tloustka krkavic u pacientu s hyperlipoproteinemiemi, s ischemickou chorobou srdecní a u zdravých osob.

Non-invasive measurement of the intima-media thickness (IMT) of the carotid artery and flow-mediated dilatation (FMD) of the brachial artery are increasingly used as surrogate markers of vascular disease. Using ultrasound, we measured the diameter of the popliteal artery at rest and during reactive hyperaemia after release of 5-minute arterial occlusion. We also measured IMT of the common carotid artery. In 29 control subjects (average age 35 years) we demonstrated an increase in the diameter by 6.0 +/- 3.3% (p < 0.05), in 29 asymptomatic patients with hyperlipidemia (without therapy, average age 46 years) only by 0.9 +/- 3.0% and in patients with coronary heart disease (average age 50 years) only by 0.2 +/- 2.7%. The difference between patients and control subjects was highly significant (p < 0.001). IMT was 0.58 +/- 0.10 mm, 0.78 +/- 0.17 mm and 1.03 +/- 0.25 mm respectively (p < 0.001). We conclude that in patients FMD of the popliteal artery is smaller and IMT of the common carotid artery is thicker than in controls.

Novel glomerular lipoprotein deposits associated with apolipoprotein E2 homozygosity.

BACKGROUND: Hyperlipoproteinemia is occasionally associated with severe glomerular injury caused by abnormal accumulation of lipid in glomeruli, which occurs in conditions such as lipoprotein glomerulopathy (LPG). This study investigates the cases of two siblings with homozygous apolipoprotein (apo) E2 who show unique histologic features, massive proteinuria, and dysbetalipoproteinemia. METHODS: Histologic studies were performed using renal biopsy specimens. Plasma lipoproteins were extensively characterized. The exons of the apo E genes were sequenced to avoid missing any mutations. RESULTS: Histologically, the siblings' condition resembled LPG by light microscopy studies. Electron microscopy studies revealed large lipoid deposits in the paramesangium, subendothelium, and subepithelium of the glomeruli, which were different from LPG in terms of not forming the layered structure resembling a fingerprint even in large lipoprotein thrombi, and mesangial foam cells. Immunohistochemically, the lipoid deposits contained apo E and apo B. These patients did not have either diabetic nephropathy or other known forms of glomerulonephritis. The sequence of exons of the apo E genes revealed homozygosity for apo E2 in both cases. CONCLUSION: The extensive lipoprotein deposition in glomeruli, which resembles LPG, can also occur in apo E2 homozygous individuals, but in a distinct fashion. Because the two cases were siblings, they may have other shared alleles, in addition to the apo E2 allele, that negatively affect processing of lipoproteins and lead to abnormal accumulation of lipoprotein deposits in glomeruli.

[Activity of the genome of cardiomyocytes as an indicator of the development of adaptive changes in the myocardium following exposure of the central nervous system to electromagnetic fields]. / Aktivnost' genoma kardiomiotsitov kak pokazatel' razvitiia adaptivnykh izmenenii v miokarde pri vliianii élektromagnitnykh polei na tsentral'nuiu nervnuiu sistemu.

Methods of cardiomyocyte nuclei isolation from the myocard homogeneous mixture, and of cardiomyocyte genome activity estimation were elaborated. In the experiments with hyperlipoproteidemic rats, cardiomyocyte genome activity was shown to reflect the primary adaptive changes in the myocard, and to serve a reliable index of their influence on the CNS regulatory centres exposed to electromagnetic field, which is used for hyperlipoproteidemia treatment. The cardiomyocyte genome activity was used to distinguish between three types of development of adaptive reactions in the myocard.

Compound heterozygosity for a Wolman mutation is frequent among patients with cholesteryl ester storage disease.

Cholesteryl ester storage disease and Wolman disease are rare autosomal recessive lipoprotein-processing disorders caused by mutations in the gene encoding human lysosomal acid lipase. Thus far we have elucidated the genetic defects in 15 unrelated CESD patients. Seven were homozygotes for the prevalent hLAL exon 8 splice junction mutation which results in incomplete exon skipping, while eight probands were compound heterozygotes for E8SJM and a rare mutation on the second chromosome. In this report, we describe the molecular basis of CESD in three compound heterozygous subjects of Czech and Irish origin. RFLP and DNA sequence analysis revealed that they were heteroallelic for the common G(934)-->A substitution in exon 8 of the hLAL gene and a mutation which, if inherited on both alleles, would be expected to result in complete loss of enzyme activity and to cause Wolman disease. In patients A. M. and J. J., two nucleotide deletions in exons 7 and 10 were detected, involving a T at position 722, 723, or 724 and a G in a stretch of five guanosines at positions 1064;-1068 of the hLAL cDNA. Both mutations result in premature termination of protein translation at residues 219 and 336, respectively, and in the production of truncated, inactive enzymes. Subject D. H., in contrast, is a compound heterozygote for the Arg(44)-->Stop mutation previously described in a French CESD proband. Combined with data in the literature, our results demonstrate that compound heterozygosity for a mutation causing Wolman disease is common among cholesteryl ester storage disease patients.

[Familial hyperlipoproteinemias--correlations between phenotypes and genotypes]. / Familiární hyperlipoproteinémie--korelace nálezu ve fenotypu s genotypem.

Within the grant project patients with familial hyperlipoproteinaemias have been examined. The examination was performed in the oldest lipid clinic and research laboratory in the world. The classification of lipid metabolism disorders was based upon a detailed biochemical analysis of plasma lipids including electrophoresis and assessment of apolipoprotein levels. Then optimal treatment regimen could be established. The project was aimed to evaluate the efficacy of different treatment regimens in different types of hyperlipoproteinaemias. Biochemical parameters and mainly the impact of treatment of hyperlipoproteinaemia on morphology and function of the vessel wall was monitored. The non-invasive ultrasound measurement of the intima thickness of carotid arteries was used. For more precise diagnosis of genetically determined disorders of lipid metabolism a large scale of methods of molecular biology was introduced. These methods enable confirmation of familial hypercholesterolaemia, familial defective apolipoprotein B-100 or studying polymorphism of apolipoprotein E. The effort of the authors of the project was to maximally utilise the results of basic and applied research in formulating recommendations for everyday practice of physicians.