Biomedical subjects

Jan Albert Kuivenhoven

Publications and source records attributed to Jan Albert Kuivenhoven.

At least 19 recordsLinked to original sources

PubMed2026

Drug targets for lipid modification and risk of type 2 diabetes: a cis-Mendelian randomization study.

BACKGROUND AND AIMS: Reducing plasma levels of low-density lipoprotein cholesterol (LDL-C) is the cornerstone in the prevention of coronary artery disease (CAD) but may also increase risk of type 2 diabetes (T2D). A comprehensive examination of the genetic evidence of T2D related side-effects of all current lipid-modifying drugs, including those in development, has not yet been performed. METHODS: This cis-Mendelian randomization study used individual level data from the UK Biobank, Lifelines, and publicly available genome-wide association data. We identified loci that are either targeted directly with drugs, or alternatively, targeting their gene products (mRNA and/or protein). Included are, in alphabetical order, the loci ACLY, ANGPTL3, ANGPTL4, APOB, APOC3, CETP, HMGCR, LDLR, LIPG, LPA, MTTP, NPC1L1, and PCSK9. We used cis-genetic instruments weighted for LDL-C, HDL-C, triglycerides, and apolipoproteins as downstream proxies for the drug targets. Main outcomes were prevalent and incident T2D, with CAD as a contrast outcome. RESULTS: Lipid modification through HMGCR is predicted to reduce CAD risk and increase T2D risk. Modification through targeting APOC3, LDLR, LPA, MTTP, NPC1L1, and PCSK9 is predicted to reduce CAD risk without a change in T2D risk. Modification through ANGPTL4 and CETP is predicted to reduce risk of both CAD and T2D. For ACLY, ANGPTL3, APOB, and LIPG, we found evidence for neither CAD nor T2D. CONCLUSIONS: This study provides genetic evidence for variation in diabetes-related side-effects of different lipid-modifying drugs, with potential relevance for future clinical trials and individual treatment decisions.

Humans↗

PubMed2006

Cholesteryl ester transfer protein and hyperalphalipoproteinemia in Caucasians.

It is unclear whether cholesteryl ester transfer protein (CETP) contributes to high density lipoprotein cholesterol (HDL-C) levels in hyperalphalipoproteinemia (HALP) in Caucasians. Moreover, even less is known about the effects of hereditary CETP deficiency in non-Japanese. We studied 95 unrelated Caucasian individuals with HALP. No correlations between CETP concentration or activity and HDL-C were identified. Screening for CETP gene defects led to the identification of heterozygosity for a novel splice site mutation in one individual. Twenty-five heterozygotes for this mutation showed reduced CETP concentration (-40%) and activity (-50%) and a 35% increase of HDL-C compared with family controls. The heterozygotes presented with an isolated high HDL-C, whereas the remaining subjects exhibited a typical high HDL-C/low-triglyceride phenotype. The increase of HDL-C in the CETP-deficient heterozygotes was primarily attributable to increased high density lipoprotein containing apolipoprotein A-I and A-II (LpAI:AII) levels, contrasting with an increase in both high density lipoprotein containing apolipoprotein A-I only and LpAI:AII in the other group. This study suggests the absence of a relationship between CETP and HDL-C levels in Caucasians with HALP. The data furthermore indicate that genetic CETP deficiency is rare among Caucasians and that this disorder presents with a phenotype that is different from that of subjects with HALP who have no mutation in the CETP gene.

Adult↗

PubMed2006

Adeno-associated virus LPL(S447X) gene therapy in LDL receptor knockout mice.

BACKGROUND: Overexpression of lipoprotein lipase (LPL) protects against atherosclerosis in genetically engineered mice. We tested whether a gene therapy vector that delivers human (h) LPL(S447X) cDNA to skeletal muscle could induce similar effects. METHODS: LDL receptor knockout (LDLr-/-) mice were injected intramuscular (i.m.) with adeno-associated virus serotype 1 (AAV1) LPL(S447X) or PBS. Four weeks later they were started on an atherogenic diet for 12 weeks. After termination, atherosclerosis was assessed and homogenates of muscle and liver tissue were analyzed. RESULTS: AAV1-treated mice showed hLPL concentrations of 768+/-293 ng/mL in post-heparin plasma associated with 48% reductions of fasting triglycerides (TG) levels (p<0.0001). In the absence of an effect on total cholesterol (TC) levels, no effects on atherosclerosis were found. An increase in lipid content of injected muscles was accompanied by a significant decrease of TG (-20%, p<0.0001) and free cholesterol (FC) content (-24%, p<0.0001) in liver homogenates. CONCLUSIONS: The data show that transgenic hLPL(S447X) on top of endogenous murine LPL reduces fasting TG levels in plasma but has no effect on atherosclerosis in LDLr-/- mice. While lipid accumulation in the injected muscle was anticipated, this coincided with an interesting decrease of both TG and FC in liver homogenates.

Animals↗

PubMed2006

Enhanced apoB48 metabolism in lipoprotein lipase X447 homozygotes.

RATIONALE: Lipoprotein lipase (LPL) X447 homozygotes are characterized by enhanced conversion of TRL apoB100. Here, we set out to investigate whether this LPL variant is also associated with enhanced apoB48 clearance. Therefore, we evaluated apoB48 kinetics in X447 homozygotes in the fed state by infusion of isotope L-[1-(13)C]-valine and subsequent compartmental modeling. METHODS AND RESULTS: ApoB48 metabolism was assessed in five X447 homozygotes (X/X genotype) and five S447 homozygotes (S/S genotype). Subjects were continuously fed and received infusion of stable isotope L-[1-(13)C]-valine. Results were analyzed by SAAM II modeling. Fasting (2.4-fold, p=0.02) as well as non-fasting (1.6-fold, p=0.09) apoB48 concentration was increased in the X447 homozygotes compared to S447 homozygotes. In addition, the X447 homozygotes exhibited a 1.7-fold higher apoB48 poolsize (p=0.04). Interestingly, apoB48 fractional catabolic rate (FCR) was 1.9-fold higher (p=0.007) and apoB48 synthesis was more than two-fold higher (p=0.006) in the X447 homozygotes compared to S447 homozygotes. CONCLUSION: In the present study, we show that X447 homozygotes exhibit enhanced apoB48 clearance. Previously, these homozygotes were shown to present with enhanced apoB100 TRL conversion. Combined, this LPLS447X gain of function variant affects apoB48 as well as apoB100 TRL metabolism.

Apolipoprotein B-48↗

PubMed2006

AAV1-LPL(S447X) gene therapy reduces hypertriglyceridemia in apoE2 knock in mice.

UNLABELLED: Intramuscular (IM) application of adeno-associated virus serotype 1 (AAV1) for the delivery of human lipoprotein lipase (hLPL) was previously shown efficacious in mice with chylomicronemia. The current study addresses whether AAV1-LPL(S447X) can reduce elevated triglyceride (TG) levels in mice with attenuated clearance of TG-rich remnant particles. METHODS: Female mice, expressing human apoE2 but deficient for endogenous apoE (apoE2KI) received IM injections of AAV1-LPL(S447X) (n=6; 8 x 10(12) gc/kg; 4-sites) or PBS (n=5). Following lipid monitoring, the mice were challenged with intravenous Intralipid injections, and sacrificed 3 months after treatment. RESULTS: In the mice that received LPL gene therapy, a marked increase of post-heparin hLPL protein levels (averaging 517+/-277 ng/mL vs. 4+/-3 ng/mL in apoE2KI-untreated) induced 20% reductions of fasting plasma TG levels (p<0.05). This was accompanied by two-fold increased TG clearance rates after Intralipid administration at 6 weeks after treatment (p<0.05). Post-mortem analyses revealed increased levels of TG (2-fold, p<0.005) and cholesterol (1.7-fold, p<0.001) in the treated muscles. CONCLUSIONS: IM application of AAV1-LPL(S447X) is effective in reducing TG levels in a mouse model for type III dyslipidemia. Thus, hypertriglyceridemia caused by attenuated uptake of TG-rich lipoproteins can be alleviated by increasing lipolytic function of the skeletal muscle tissue.

Animals↗

PubMed2006

Evidence for a complex relationship between apoA-V and apoC-III in patients with severe hypertriglyceridemia.

The relevance of apolipoprotein A-V (apoA-V) for human lipid homeostasis is underscored by genetic association studies and the identification of truncation-causing mutations in the APOA5 gene as a cause of type V hyperlipidemia, compatible with an LPL-activating role of apoA-V. An inverse correlation between plasma apoA-V and triglyceride (TG) levels has been surmised from animal data. Recent studies in human subjects using (semi)quantitative immunoassays, however, do not provide unambiguous support for such a relationship. Here, we used a novel, validated ELISA to measure plasma apoA-V levels in patients (n = 28) with hypertriglyceridemia (HTG; 1.8-78.7 mmol TG/l) and normolipidemic controls (n = 42). Unexpectedly, plasma apoA-V levels were markedly increased in the HTG subjects compared with controls (1,987 vs. 258 ng/ml; P < 0.001). In the HTG group, apoA-V and TG were positively correlated (r = +0.44, P = 0.02). In addition, we noted an increased level of the LPL-inhibitory protein apoC-III in the HTG group (45.8 vs. 10.6 mg/dl in controls; P < 0.001). The correlation between apoA-V and TG levels in the HTG group disappeared (partial r = +0.09, P = 0.65) when controlling for apoC-III levels. In contrast, apoC-III and TG remained positively correlated in this group when controlling for apoA-V (partial r = +0.43, P = 0.025). Our findings suggest that in HTG patients, increased TG levels are accompanied by high plasma levels of apoA-V and apoC-III, apolipoproteins with opposite modes of action. This study provides evidence for a complex interaction between apoA-V and apoC-III in patients with severe HTG.

Apolipoprotein A-V↗

PubMed2006

Lipoprotein lipase S447X: a naturally occurring gain-of-function mutation.

Lipoprotein lipase (LPL) hydrolyzes triglycerides in the circulation and promotes the hepatic uptake of remnant lipoproteins. Since the gene was cloned in 1989, more than 100 LPL gene mutations have been identified, the majority of which cause loss of enzymatic function. In contrast to this, the naturally occurring LPL(S447X) variant is associated with increased lipolytic function and an anti-atherogenic lipid profile and can therefore be regarded as a gain-of-function mutation. This notion combined with the facts that 20% of the general population carries this prematurely truncated LPL and that it may protect against cardiovascular disease has led to extensive clinical and basic research into this frequent LPL mutant. It is only until recently that we begin to understand the molecular mechanisms that underlie the beneficial effects associated with LPL(S447X). This review summarizes the current literature on this interesting LPL variant.

Animals↗

PubMed2006

Cholesteryl ester transfer protein (CETP) inhibition beyond raising high-density lipoprotein cholesterol levels: pathways by which modulation of CETP activity may alter atherogenesis.

Raising high-density lipoprotein cholesterol (HDL-C) is a promising strategy in the struggle to prevent cardiovascular disease, and cholesteryl ester transfer protein (CETP) inhibitors have been developed to accomplish this. The first results are encouraging, and, in fact, in rabbits, inhibition of CETP reduces atherosclerosis. Because human data regarding the reduction of atheroma burden require more time, the biochemical mechanisms underlying the putative atheroprotection of CETP inhibitors are currently dissected, and several pathways have emerged. First, CETP inhibition increases HDL-C and reduces low-density lipoprotein cholesterol (LDL-C) levels consistent with CETP lipid transfer activity and its role in reverse cholesterol transport (RCT). This coincides with putative beneficial increases in both HDL and LDL size. However, many aspects regarding the impact of CETP inhibition on the RCT pathway remain elusive, in particular whether the first step concerning cholesterol efflux from peripheral tissues to HDL is influenced. Moreover, the relevance of scavenger receptor BI and consequently the central role of HDL in human RCT is still unclear. Second, CETP inhibition was shown recently to increase antioxidant enzymes associated with HDL, in turn associated with decreased oxidation of LDL. Atheroprotection in man is currently anticipated based on the improvement of these biochemical parameters known to influence atherosclerosis, but final confirmation regarding the impact of CETP inhibition on cardiovascular outcome will have to come from trials evaluating clinical end points.

Adipose Tissue↗

PubMed2006

Correction of feline lipoprotein lipase deficiency with adeno-associated virus serotype 1-mediated gene transfer of the lipoprotein lipase S447X beneficial mutation.

Human lipoprotein lipase (hLPL) deficiency, for which there currently exists no adequate treatment, leads to excessive plasma triglycerides (TGs), recurrent abdominal pain, and life-threatening pancreatitis. We have shown that a single intramuscular administration of adeno-associated virus (AAV) serotype 1 vector, encoding the human LPL(S447X) variant, results in complete, long-term normalization of dyslipidemia in LPL(/) mice. As a prelude to gene therapy for human LPL deficiency, we tested the efficacy of AAV1-LPL(S447X) in LPL(/) cats, which demonstrate hypertriglyceridemia (plasma TGs, >10,000 mg/dl) and clinical symptoms similar to LPL deficiency in humans, including pancreatitis. Male LPL(/) cats were injected intramuscularly with saline or AAV1-LPL(S447X) (1 x 10(11)-1.7 x 10(12) genome copies [GC]/kg), combined with oral doses of cyclophosphamide (0-200 mg/m(2) per week) to inhibit an immune response against hLPL. Within 3-7 days after administration of >or=5 x 10(11) GC of AAV1-LPL(S447X) per kilogram, the visible plasma lipemia was completely resolved and plasma TG levels were reduced by >99% to normal levels (10-20 mg/dl); intermediate efficacy (95% reduction) was achieved with 1 x 10(11) GC/kg. Injection in two sites, greatly limiting the amount of transduced muscle, was sufficient to completely correct the dyslipidemia. By varying the dose per site, linear LPL expression was demonstrated over a wide range of local doses (4 x 10(10)-1 x 10(12) GC/site). However, efficacy was transient, because of an anti-hLPL immune response blunting LPL expression. The level and duration of efficacy were significantly improved with cyclophosphamide immunosuppression. We conclude that AAV1-mediated delivery of LPL(S447X) in muscle is an effective means to correct the hypertriglyceridemia associated with feline LPL deficiency.

Animals↗

PubMed2005

Serum lipoprotein lipase concentration and risk for future coronary artery disease: the EPIC-Norfolk prospective population study.

BACKGROUND: Lipoprotein lipase (LPL) is associated with coronary artery disease (CAD) risk, but prospective population data are lacking. This is mainly because of the need for cumbersome heparin injections, which are necessary for LPL measurements. Recent retrospective studies, however, indicate that LPL concentration can be reliably measured in serum that enabled evaluation of the prospective association between LPL and future CAD. METHODS AND RESULTS: LPL concentration was determined in serum samples of men and women in the EPIC-Norfolk population cohort who developed fatal or nonfatal CAD during 7 years of follow-up. For each case (n=1006), 2 controls, matched for age, sex, and enrollment time, were identified. Serum LPL concentration was lower in cases compared with controls (median and interquartile range: 61 [43-85] versus 66 [46-92] ng/mL; P<0.0001). Those in the highest LPL concentration quartile had a 34% lower risk for future CAD compared with those in the lowest quartile (odds ratio [OR] 0.66; confidence interval [CI], 0.53 to 0.83; P<0.0001). This effect remained significant after adjustment for blood pressure, diabetes, smoking, body mass index, and low-density lipoprotein (LDL) cholesterol (OR, 0.77; CI, 0.60-0.99; P=0.02). As expected from LPL biology, additional adjustments for either high-density lipoprotein cholesterol (HDL-C) or triglyceride (TG) levels rendered loss of statistical significance. Of interest, serum LPL concentration was positively linear correlated with HDL and LDL size. CONCLUSIONS: Reduced levels of serum LPL are associated with an increased risk for future CAD. The data suggest that high LPL concentrations may be atheroprotective through decreasing TG levels and increasing HDL-C levels.

Aged↗

PubMed2005

Enhanced conversion of triglyceride-rich lipoproteins and increased low-density lipoprotein removal in LPLS447X carriers.

OBJECTIVE: Lipoprotein lipase (LPL) exerts 2 principal actions, comprising enzymatic hydrolysis of triglyceride-rich lipoproteins (TRLs) and nonenzymatic ligand capacity for enhancing lipoprotein removal. The common LPLS447X variant has been associated with cardiovascular protection, for which the mechanism is unknown. We therefore evaluated enzymatic and nonenzymatic consequences of this LPL variant on TRL metabolism. METHODS AND RESULTS: TRL apolipoprotein B100 (apoB100) metabolism was determined in 5 homozygous LPLS447X carriers and 5 controls. Subjects were continuously fed and received infusion of stable isotope l-[1-(13C)]-valine. Results were analyzed by SAAMII modeling. Also, preheparin and postheparin LPL concentration and activity were measured. Compared with controls, carriers presented increased very low-density lipoprotein 1 (VLDL1) to VLDL2 apoB100 flux (P=0.04), increased VLDL2 to intermediate-density lipoprotein (IDL) apoB100 flux (P=0.02), increased IDL to low-density lipoprotein (LDL) apoB100 flux (P=0.049), as well as an increased LDL clearance (P=0.04). Additionally, IDL apoB100 synthesis was attenuated (P=0.05). Preheparin LPL concentration was 4-fold higher compared with controls (P=0.01), and a correlation was observed between preheparin LPL concentration and LDL clearance (r2=0.92; P=0.01). CONCLUSIONS: Enhanced TRL conversion and enhanced LDL removal combined with increased preheparin LPL concentration suggest increased enzymatic consequences as well as increased nonenzymatic consequences of LPL in LPLS447X carriers, which might both contribute to the cardiovascular benefit of this LPL variant.

Adult↗

PubMed2005

Lipoprotein lipase gene polymorphisms and the risk of target vessel revascularization after percutaneous coronary intervention.

OBJECTIVES: We sought to identify polymorphisms in genes that predispose to restenosis. BACKGROUND: Variations in the lipoprotein lipase (LPL) gene have been implicated in a number of pathophysiologic conditions associated with coronary heart disease. The present study examines the impact of polymorphisms in the LPL gene on restenosis (defined by target vessel revascularization [TVR]) in a large patient population undergoing percutaneous coronary intervention (PCI). A mouse model for restenosis was used to further investigate LPL's role in restenosis. METHODS: The GENetic DEterminants of Restenosis (GENDER) project is a multicenter, prospective study design that enrolled 3,104 consecutive patients after successful PCI. These patients were genotyped for four different LPL gene polymorphisms. In apolipoprotein E (ApoE)*3-Leiden transgenic mice, arterial messenger ribonucleic acid (mRNA) was used to assess LPL expression during a cuff-induced restenotic process. RESULTS: Using multivariable analysis, carriers of the 447Ter allele of the LPL enzyme showed a lower risk of TVR compared with 447Ser homozygotes (p = 0.005). In the mouse model, LPL mRNA levels were increased 40-fold compared with control arteries at 6 h after cuff placement. CONCLUSIONS: The LPL C/G polymorphism (Ser447Ter), resulting in a truncation of the two C-terminal amino acids of the mature LPL protein, appears to be an important protective factor for TVR in humans. The role of LPL in this process was further established in a mouse model, where LPL expression was very strongly up-regulated in the target arterial wall, suggesting a contribution of this lipolytic enzyme to restenosis. Possibly, LPL Ser447Ter genotyping may lead to better risk stratification and tailored therapy in the prevention of restenosis after PCI.

Angioplasty, Balloon, Coronary↗

PubMed2005

Compromised LCAT function is associated with increased atherosclerosis.

BACKGROUND: Prospective epidemiological studies have shown that low plasma levels of HDL cholesterol (HDL-C) are associated with an increased risk for cardiovascular disease (CVD). Despite nearly 40 years of research, however, it is unclear whether this also holds true for individuals with severely reduced levels of HDL-C due to mutations in the lecithin:cholesterol acyltransferase (LCAT) gene. Better insight into CVD risk in these individuals may provide clues toward the potential of LCAT as a pharmaceutical target to raise HDL-C levels. METHODS AND RESULTS: Lipids, lipoproteins, high-sensitivity C-reactive protein (CRP), and carotid artery intima-media thickness (IMT) were assessed in 47 heterozygotes for LCAT gene mutations and 58 family controls. Compared with controls, heterozygotes presented with a mean 36% decrease in HDL-C levels (P<0.0001), a 23% increase in triglyceride levels (P<0.0001), and a 2.1-fold increase in CRP levels (P<0.0001). Mean carotid IMT was significantly increased in heterozygotes compared with family controls (0.623+/-0.13 versus 0.591+/-0.08 mm). After adjustment for age, gender, and alcohol use, this difference proved statistically significant (P<0.0015). CONCLUSIONS: The data show that heterozygosity for LCAT gene defects is associated with low HDL-C levels and elevated concentration of triglycerides and CRP in plasma. This phenotype underlies increased IMT in carriers versus controls, which suggests that LCAT protects against atherosclerosis. This in turn indicates that targeting LCAT to raise HDL-C may reduce CVD risk.

Adult↗

PubMed2005

Complete rescue of lipoprotein lipase-deficient mice by somatic gene transfer of the naturally occurring LPLS447X beneficial mutation.

The naturally occurring human lipoprotein lipase S447X variant (LPLS447X) exemplifies a gain-of function mutation with significant benefits including decreased plasma triglycerides (TG), increased high-density lipoprotein (HDL) cholesterol, and reduced risk of coronary artery disease. The S447X variant may be associated with higher LPL catalytic activity; however, in vitro data supporting this hypothesis are contradictory. We wanted to investigate the in vivo mechanism by which the LPLS447X variant improves the lipid profile of S447X carriers. We conducted a functional assessment of human LPLS447X compared with LPLWT in mice. LPL variants were compared in the absence of endogenous mouse LPL in newborn LPL(-/-) mice by adenoviral-mediated gene transfer. LPL(-/-) mice normally exhibit severe hypertriglyceridemia and die within 48 hours of birth. LPLWT gene transfer prolonged the survival of mice up to 21 days. In contrast, LPLS447X completely rescued 95% of the mice to adulthood and increased LPL catalytic activity in postheparin plasma 2.1-fold compared with LPLWT at day 3 (P=0.003). LPLS447X also reduced plasma TG 99% from baseline (P<0.001), 2-fold more than LPLWT, (P<0.01) and increased plasma HDL cholesterol 2.9-fold higher than LPLWT (P<0.01). These data provide in vivo evidence that the increased catalytic activity of LPLS447X improves plasma TG clearance and increases the HDL cholesterol pool compared with LPLWT.

Adenoviridae↗

PubMed2005

Effectiveness of inhibition of cholesteryl ester transfer protein by JTT-705 in combination with pravastatin in type II dyslipidemia.

The inhibition of cholesteryl ester transfer protein (CETP) has recently been shown to effectively increase high-density lipoprotein (HDL) cholesterol. This study examined the use of the CETP inhibitor JTT-705 combined with pravastatin. In a randomized, double-blind, placebo-controlled trial, 155 patients with type II dyslipidemia using pravastatin 40 mg were treated with placebo or JTT-705 300 or 600 mg. Four weeks of treatment with JTT-705 600 mg led to a 30% decrease in CETP activity (p <0.001), a 28% increase in HDL cholesterol (p <0.001), and a 5% decrease in low-density lipoprotein cholesterol (p <0.03). Combination therapy using JTT-705 and pravastatin effectively increases HDL cholesterol levels and is safe and well tolerated up to 4 weeks of administration.

Amides↗

PubMed2005

Genetic determinants of plasma HDL-cholesterol levels in familial hypercholesterolemia.

The objective of this study was to determine the extent to which common genetic variants can explain the variation of high-density lipoprotein cholesterol (HDL-C) plasma levels in familial hypercholesterolemia (FH). FH is characterized by elevated low-density lipoprotein cholesterol levels and premature cardiovascular disease (CVD). Although low HDL-C levels have been shown to affect the severity of the clinical phenotype, little is known about the factors that determine HDL-C levels in these patients. A cohort of 1002 heterozygous FH patients was genotyped for polymorphisms in the genes encoding for ATP-binding cassette transporter A1, apolipoprotein (apo) AIV, apoCIII, apoE, cholesteryl transfer ester protein, hepatic lipase, lipoprotein lipase, and two paraoxonases. Multiple linear regression showed that, together, these polymorphisms explain only 3.9% of the variation of HDL-C plasma levels. When significant two-way interactions between the polymorphisms were also taken into account, the explained variation rose to 12.5%. In a regression model that also incorporated sex, smoking, alcohol use, body mass index, and concomitant beta-blocker use as covariates, the explained variation of HDL-C plasma levels even increased to 32.5%. This study provides direct evidence that multiple, modestly penetrant, but highly prevalent, polymorphisms can explain a substantial part of the variation of HDL-C plasma levels in a representative large cohort of heterozygous FH patients.

ATP Binding Cassette Transporter 1↗

PubMed2005

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.

Animals↗

PubMed2005

Inherited disorders of HDL metabolism and atherosclerosis.

PURPOSE OF REVIEW: Genetic disorders of HDL metabolism are rare and, as a result, the assessment of atherosclerosis risk in individuals suffering from these disorders has been difficult. Ultrasound imaging of carotid arteries has provided a tool to assess the risk in hereditary hypo and hyperalphalipoproteinemia. This review gives a comprehensive summary. RECENT FINDINGS: Epidemiological studies have unequivocally shown that HDL cholesterol levels are inversely related to coronary artery disease risk, but the literature concerning genetic disorders of HDL metabolism provides less convincing information. Fortuitously, we were able to directly compare carotid intima media thickness data of substantial numbers of individuals with mutations in either apolipoprotein A-I (apoA-I), ATP binding cassette AI (ABCA1), lecithin: cholesterol acyltransferase (LCAT) or cholesteryl ester transfer protein. These data show that carriers of an apoA-I mutation exhibit the most pronounced accelerated atherosclerosis compared with those carrying mutations in ABCA1 and LCAT. Heterozygosity for a non-sense mutation in cholesteryl ester transfer protein did, by contrast, not distinguish carriers from controls in terms of intima media thickness progression. We will discuss these results in the context of the current literature. SUMMARY: Intima media thickness studies have provided evidence that hypoalphalipoproteinemia due to mutations in apoA-I, ABCA1, and LCAT is associated with increased progression of atherosclerosis. In contrast, hyperalphalipoproteinemia as a result of loss of cholesteryl ester transfer protein function is associated with unaltered atherosclerosis progression compared with family controls. This insight is of interest, since it can assist in the prioritizing of antiatherogenic therapy by increasing HDL cholesterol levels.

ATP Binding Cassette Transporter 1↗