Gene therapy for lipoprotein lipase deficiency: working toward clinical application.

Lipoprotein lipase (LPL) deficiency causes hypertriglyceridemia and recurrent, potentially life-threatening pancreatitis. There currently is no adequate treatment for this disease. Previously, we showed that intramuscular administration of an adeno-associated virus serotype 1 (AAV1) vector encoding the human LPL(S447X) variant cDNA (AAV1-LPL(S447X)) normalized the dyslipidemia of LPL-/- mice for more than 1 year. In preparation for a clinical trial, we evaluated the safety and biodistribution of AAV1-LPL(S447X) in wild-type mice and fully characterized six LPL-deficient patients. Toxicological analysis in mice showed that intramuscular administration was well tolerated. Acute inflammatory response markers were transiently increased, and anti- AAV1 antibodies were generated. Histological analyses indicated a dose-dependent reversible spleen hyperplasia, and myositis at the injection sites. Biodistribution data showed short-term vector leakage from injection sites into the circulation, followed by liver-mediated clearance. Persistence of vector DNA was limited to the injected muscle and draining lymph nodes, and spread to reproductive organs was limited. Characterization of LPL-deficient patients showed that all patients presented with hypertriglyceridemia and recurrent pancreatitis. LPL catalytic activity was absent, but LPL protein levels were 20-100% of normal. Myoblasts derived from skeletal muscle biopsies of these patients were efficiently transduced by AAV1-LPL(S447X) and secreted active LPL. These data support the initiation of a clinical trial in LPL-deficient patients, for which regulatory approval has been granted.

Phenotypic correction of feline lipoprotein lipase deficiency by adenoviral gene transfer.

Previous studies have revealed that adenovirus-mediated ectopic liver expression of human LPL (huLPL) can efficiently mediate plasma triacylglycerol (TG) catabolism in mice despite its native expression in adipose and muscle tissue. We aimed to explore the feasibility of liver-directed gene transfer and enzyme replacement for human LPL deficiency in a larger, naturally occurring feline animal model of complete LPL deficiency that is remarkably similar in phenotype to the human disorder. A cohort of LPL-deficient (LPL -/-) cats was given an intravenous injection of 8 x 10(9) PFU/kg of a CMV promoter/enhancer-driven, E1/E3-deleted adenoviral (Ad) vector containing a 1.36-kb huLPL cDNA (Ad-LPL) or reporter alkaline phosphatase gene (Ad-AP). After Ad-LPL administration, active, heparin-releasable huLPL was readily detected along with a 10-fold reduction in plasma TGs, disappearance of plasma TG-rich lipoproteins up to day 14, and enhanced clearance of an excess intravenous fat load on day 9. However, antibody against the huLPL protein was detected on day 14 in cats receiving Ad-LPL and adenovirus-specific neutralizing antibody was present 7 days after gene transfer in both cat cohorts. Tissue-specific expression of the huLPL transgene relative to controls was confirmed by RT-PCR. While huLPL expression was evident in the liver, other tissues including spleen and lung expressed huLPL message, in direct correlation with histological evidence of increased Oil red O (ORO)-positive neutral lipid influx. In contrast, intravenous LPL enzyme replacement therapy (ERT) led to rapid disappearance of 9000 mU/kg of active bovine LPL enzyme from the circulation, with t1/2 occurring at <10 min in two LPL-/- cats. Heparin injection 1 hr later released <10% of the original bovine LPL, further indicating its rapid systemic clearance, inactivation, or degradation as well as its ineffectiveness as a viable therapeutic alternative for complete LPL deficiency. Although LPL gene transfer and expression via this first-generation Ad vector was limited by the immune response against both the human LPL protein and adenovirus our results clearly provide a key advance supporting further development of LPL gene therapy as a viable therapeutic option for clinical LPL deficiency.

A largely random AAV integration profile after LPLD gene therapy.

The clinical application of adeno-associated virus vectors (AAVs) is limited because of concerns about AAV integration-mediated tumorigenicity. We performed integration-site analysis after AAV1-LPL(S447X) intramuscular injection in five lipoprotein lipase-deficient subjects, revealing random nuclear integration and hotspots in mitochondria. We conclude that AAV integration is potentially safe and that vector breakage and integration may occur from each position of the vector genome. Future viral integration-site analyses should include the mitochondrial genome.

Efeito da administração In Bolus da heparina sódica no remodelamento de partículas lepoprotéicas associadas ao transporte reverso do colesterol / In bolus administration the effect of heparin sodium in remodeling lepoprotéicas particles associated with reverse cholesterol transport

Introdução: as doenças cardiovasculares acometem milhares de pessoas no mundo. Destas, a doença arterosclerótica está entre as de maior morbimortalidade. Para a avaliação da necessidade de intervenções hemodinâmicas e/ou revascularização miocárdica, há a necessidade da realização do cateterismo (CATE), procedimento de imagem indicado para evidenciar pontos de obstrução e determinar a melhor estratégia cirúrgica. Para a realização do CATE utiliza-se heparina sódica (5000 UI) in bolus. Atualmente, sabe-se que a heparina interfere no remodelamento de partículas lipoproteicas por liberação da lipoproteína lipase (LPL) e da lipase hepática (LH), essa ação pode alterar o transporte reverso do colesterol (TRC), em função de modificações no metabolismo das lipoproteínas. Métodos: foram selecionados por conveniência 20 pacientes, 10 do sexo masculino e 10 do sexo feminino, ambos os sexos, entre 45 e 73 anos, admitidos no Hospital Ana Neri, submetidos à cineangiocoronariografia (CATE)...

Introduction: cardiovascular diseases affect thousands of people worldwide. Of these, the atherosclerotic disease is one of the most morbidity and mortality. To evaluate the need for hemodynamic interventions and / or CABG, the catheterization (CATE) is performed, an imaging procedure to evidence obstruction and to determine the best surgical strategy. To perform CATE, is necessary to use in bolus sodium heparin (5000 IU). Currently, it is known that heparin interferes with the remodeling of the lipoprotein particles by releasing lipoprotein lipase (LPL) and hepatic lipase (HL), this action may alter the reverse cholesterol transport (TRC), by changes in lipoprotein metabolism. Methods: were selected by convenience 20 patients, 10 male and 10 female, both gender, between 45 and 73 years old, admitted to the Hospital Ana Neri, who underwent coronary angiography (CATE)...

Nutritional regulation of binding sites for lipoprotein lipase in rat heart.

Several laboratories have shown that when rats are fasted, the amount of lipoprotein lipase (LPL) at the vascular endothelium in heart (monitored as the amount released by heparin) increases severalfold without corresponding changes in the production of LPL. This suggests that there is a change in endothelial binding of LPL. To study this, (125)I-labeled bovine LPL was injected. The fraction that bound in the heart was more than twice as high in fasted than in fed rats, 4.3% compared with 1.9% of the injected dose. Refeeding reversed this in 5 h. When unlabeled LPL was injected before the tracer, the fraction of (125)I-LPL that bound in heart decreased, indicating that the binding was saturable. When isolated hearts were perfused at 4 degrees C with a single pass of labeled LPL, twice as much bound in hearts of fasted rats. We conclude that fasting causes a change in the vascular endothelium in heart such that its ability to bind LPL increases.

In-vitro lipolysis of small very low density lipoproteins from human plasma. Dependence of characteristics of end products on the serum triglyceride concentration.

Isolated, small very low density lipoproteins (VLDL) from males with plasma concentrations of VLDL triglycerides ranging between 0.92 and 8.65 mmol l-1 were incubated with lipoprotein lipase. There were no differences in the size of the VLDL particles isolated from normo-respectively hypertriglyceridaemic plasmas. After incubation, 4.5 +/- 3.5% (mean +/- SD) of the initial glyceride-glycerol remained in the incubate. This amount did not vary with the plasma VLDL concentration. The incubation mixture was separated into three density fractions: VLDL, low density lipoprotein (LDL) and a high density lipoprotein (HDL) respectively. The lipid contents of these were determined. The distribution of cholesterol and phospholipids after lipolysis was highly dependent on the plasma VLDL level. The amount of cholesterol and phospholipids recovered in the LDL density region increased with the rising plasma VLDL level, the correlation coefficients for this relationship were 0.80 and 0.66, respectively. The results thus indicate that small, similar size VLDL from normo-respectively hypertriglyceridaemic plasmas have different properties.

Lipoprotein lipase enhances removal of chylomicrons and chylomicron remnants by the perfused rat liver.

Lipoprotein lipase has been found to efficiently mediate binding of lipoproteins to cell surfaces and to the low density lipoprotein (LDL) receptor-related protein (LRP) under cell culture conditions (Beisiegel et al. 1991. Proc. Natl. Acad. Sci. USA. 88: 8242-8346). This supports the previously proposed idea that the lipase could have a role in receptor-mediated uptake of chylomicron remnants in the liver. We have investigated the effects of lipoprotein lipase on the clearance of chylomicrons during perfusions of rat livers. The chylomicrons were doubly labeled in vivo with [14C]retinol (in retinyl esters) and with [3H]oleic acid (in triacylglycerols) and were collected from lymph. In the absence of any lipase the clearance of chylomicron label from the perfusion medium was slow. Addition of lipoprotein lipase caused lipolysis of chylomicron triacylglycerols as evidenced by increased levels of 14C-labeled fatty acids in the perfusate. Simultaneously, the level of [14C]retinyl esters in the perfusate decreased dramatically, indicating core-particle removal. Similar effects were seen with an unrelated lipase from Pseudomonas fluorescens. To discriminate between the effects of lipolysis and a true liganding effect of the lipoprotein lipase protein, the active site inhibitors tetrahydrolipstatinR and hexadecylsulfonylfluoride were used to reduce or totally inhibit the catalytical activity. With lipase covalently inhibited by the latter inhibitor, lipolysis during perfusions was low or absent. Nonetheless, the inhibited enzyme had a clear effect on the removal of chylomicrons by the liver. With 1.2 micrograms of inhibited lipase/ml perfusate, about 70% of the core label had been removed after 15 min as compared to about 20% in perfusions without lipase. With identical amounts of active lipoprotein lipase protein, more than 90% of the label was removed. We conclude that any lipase causing lipolysis of chylomicrons can stimulate their clearance by the liver, but that lipoprotein lipase has an additional effect on the removal, which is not dependent on its catalytic activity.