- Email: [email protected]
Mutations in stap1 are associated with autosomal dominant hypercholesterolemia
Abstracts / Atherosclerosis 235 (2014) e11–e26 f Department of Pathology Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands; g Department of Pathology, Academic Medical Center University of Amsterdam, Amsterdam, Netherlands
Objectives: Atherosclerosis is a chronic lipid-driven inflammatory disease with a key role for macrophages. Epigenetic modifiers regulate DNA accessibility through histone modifications and fine-tune macrophage polarization. We hypothesized that targeting Hdac3 should offer a novel approach to confer atheroprotective mechanisms, since Hdac3 deletion elicits an anti-inflammatory macrophage phenotype. Methods: Bone marrow was isolated from LysMCre-Hdac3fl/fl mice (Hdac3del) and Hdac3fl/fl littermates (Hdac3wt) and transplanted to LDLR-/mice. Next we performed an in vivo foam cell formation experiment and assessed the mice during experimental atherosclerosis. Results: Pathway analysis of expression data indicated that Hdac3 deleted macrophages have enhanced PPARg and LXR signalling, implicating better lipid handling. Indeed, expression of LXR and PPARg target genes were upregulated and both in vivo and in vitro foam cell formation was reduced in Hdac3-deleted macrophages. In experimental atherosclerosis, we observed that macrophage Hdac3 deficiency resulted in slightly increased plaque size as a result of enhanced fibrosis, resulting in a two-fold thicker fibrous cap. We could confirm this in vitro by demonstrating that Hdac3deleted macrophages increased collagen production in isolated vascular smooth muscle cells. This was linked to an upregulation of TGFb expression in Hdac3 deleted macrophages, which was a consequence of the absence of Hdac3 repression on TGFb expression. Furthermore, examining human atherosclerotic samples we observed that Hdac3 gene expression is upregulated in unstable plaques, it colocalizes with pro-inflammatory M1 macrophages and that Hdac3 expression negatively correlates with TGFb expression. Conclusion: Here, we show that altering the macrophage’s epigenetic landscape through Hdac3 deletion changes the macrophage to a atherosclerosis-beneficial phenotype and thus may offer a novel manner for management of atherosclerosis. Supported by the Netherlands Heart Foundation (2013-T003 and 2007T067). Gene-environment interactions and epigenetics EAS-0760. IRON AS A RISK FACTOR FOR ATHEROSCLEROSIS: CONFIRMING THE IRON HYPOTHESIS IN A MOUSE MODEL OF HEMOCHROMATOSIS F. Vinchia, S. Altamuraa, M. Costa da Silvaa, B. Galya, M.W. Hentzea, M.U. Muckenthalera a Molecular Medicine Partnership Unit (MMPU), UniversitatsKlinikum Heidelberg & EMBL, Heidelberg, Germany
Objectives: Iron accumulates in atherosclerotic lesions but its role in atherogenesis is still debated. In 1981, Sullivan proposed the ’iron hypothesis’, according to which iron is detrimental for the cardiovascular system, thus promoting atherosclerosis progression. Epidemiological data and animal models have provided conflicting evidence regarding the role of iron in atherosclerosis. This project is aimed at elucidating whether iron contributes to atherosclerosis and at discriminating which iron source is involved in its pathogenesis. Methods: We applied a novel mouse model of type IV Hereditary Hemochromatosis to study the susceptibility to atherosclerosis. This disease is hallmarked by systemic iron overload and macrophage-iron deficiency, thus providing a way to dissect (1) the contribution of systemic iron overload to atherosclerosis, since these mice present with high transferrin saturation and NTBI levels; (2) the contribution of macrophage-retained iron, since these mice show macrophage iron deficiency. Results: In 3 month-old hemochromatotic mice, innominate artery lesion area is significantly smaller than in age-matched controls. This is accompanied by a reduction in oxLDL accumulation in the aorta. Conversely, at 6 months of age, the mice showed a more severe atherosclerotic phenotype,
e17
as suggested by the increased lesion size and number. This is associated with higher levels of circulating and aortic oxLDLs. Moreover, we observed an increased endothelial activation, as suggested by higher expression levels of adhesion molecules and increased levels of circulating soluble adhesion molecules. The vascular oxidative status is altered as indicated by the increased aortic lipid peroxidation and the upregulation of antioxidant genes. Conclusion: Collectively, these data suggest that macrophage-iron deple-
Ă
tion is protective for early atherosclerosis, while severe systemic iron overload promotes atherosclerosis progression, thus supporting the iron hypothesis. However, the protective effect of macrophage-iron depletion is not sufficient to counteract the strongly pro-atherogenic effect of high circulating iron. Genomics and proteomics of lipid metabolism EAS-0521. MUTATIONS IN STAP1 ARE ASSOCIATED WITH AUTOSOMAL DOMINANT HYPERCHOLESTEROLEMIA S.W. Fouchiera, N.O. Stitzielb, G.M. Dallinga-Thiec, J.C.M. Meijersa, N. Zelcerd, J.J.P. Kasteleinc, J.C. Defeschea, S. Kathiresane, G.K. Hovinghc a
Experimental Vascular Medicine, Academic Medical Center, Amsterdam, Netherlands; b Cardiovascular Medicine, Brigham and Women’s Hospital, Boston, USA; c Vascular Medicine, Academic Medical Center, Amsterdam, Netherlands; d Medical Biochemistry, Academic Medical Center, Amsterdam, Netherlands; e Program in Medical and Population Genetics, Broad Institute, Boston, USA Objectives: Autosomal Dominant Hypercholesterolemia (ADH) is caused by mutations in LDLR, APOB or PCSK9. A number of patients, however, suffer from “FH4”, defined as ADH in absence of mutations in these genes. Our aim was to identify the molecular pathology in a family suffering from FH4. Methods: Parametric linkage analysis combined with exome sequencing was carried out in 13 and 3 relatives, respectively. Identified variants were validated in 400 normolipidemic controls and 400 unrelated FH4 probands, and co-segregation with the ADH phenotype was assessed in families. Results: Linkage analysis revealed suggestive LOD scores of 2.99 (Q ¼ 0.0) at 4p15.1-q13.3, 11p13-q14.1, and 13q14.13-q32.1. The linked region on chromosome 4 harbored the variant, p.Glu97Asp in STAP1 (encoding signal transducing adaptor family member 1), associated with elevated plasma LDL-c in the family. STAP1 was sequenced in the FH4 cohort. A second proband carrying p.Glu97Asp and three additional probands carrying p.Leu69Ser, p.Ile71Thr, and p.Asp207Asn were identified. All variants altered highly conserved amino acid residues and were not present in controls. The prevalence of rare putative deleterious mutations in STAP1 was higher in our FH4 cohort (1.3%) compared to the publically available databases NHLBI-ESP (0.5%) and GoNL (0.2%). A disease penetrance of 0.9 was found while investigating the four variants in the five families. STAP1 carriers (N¼35) were younger (3819 vs. 4816 years; p<0.001), had higher plasma TC (6.521.52 vs. 5.761.25 mmol/l;
e18
Abstracts / Atherosclerosis 235 (2014) e11–e26
p<0.001) and LDL-c levels (4.261.22 vs. 3.831.10 mmol/l; p¼0.001) compared to non-affected relatives (N¼89). Conclusion: The prevalence of putative deleterious mutations in STAP1 is higher in FH4 subjects compared to controls and cholesterol levels are significantly elevated in carriers versus non-carriers. This suggest that STAP1 might play a role in cholesterol metabolism. Additional studies are warranted to address the biological mechanisms underlying the ADH phenotype in STAP1 mutation carriers. Genomics and proteomics of lipid metabolism EAS-0647. LOSS-OF-FUNCTION MUTATIONS IN APOC3 AND REDUCED RISK OF ISCHEMIC VASCULAR DISEASE A. Jørgensena, R. Frikke-Schmidta, B.G. Nordestgaardb, A. TybjærgHansena a
Department of Clinical Biochemistry, Rigshospitalet Copenhagen University Hospital, Copenhagen, Denmark; b Department of Clinical Biochemistry, Herlev Hospital Copenhagen University Hospital, Herlev, Denmark Objectives: High plasma levels of nonfasting triglycerides, a marker of high remnant cholesterol, are associated with increased risk of ischemic cardiovascular disease. Whether lifelong low levels of nonfasting triglycerides, due to mutations in APOC3, associate with reduced risk of ischemic cardiovascular disease in the general population is unknown. We tested this hypothesis. Methods: Using 75,725 individuals from the general population, we first tested whether low levels of nonfasting triglycerides were associated with reduced risk of ischemic vascular disease (IVD) and ischemic heart disease (IHD) in observational analyses. Second, whether loss-of-function mutations in APOC3 which were associated with reduced levels of nonfasting triglycerides, associated with reduced risk of IVD and IHD. During a median 4 and 34 years of follow-up, 5,410 and 10,797 individuals developed IVD in observational and genetic analyses, respectively. Results: In observational analyses, hazard ratios (HRs) for individuals with nonfasting triglycerides <1.00 mmol/L compared to >4.00 mmol/L, were 0.43(95% confidence interval, 0.35-0.54) for IVD and 0.40(0.31-0.52) for IHD. Corresponding HRs for individuals with nonfasting triglycerides in the lowest compared to the highest quintile were 0.55(0.47-0.65) and 0.49(0.40-0.59). Heterozygosity for loss-of-function mutations in APOC3 associated with mean reductions in plasma nonfasting triglycerides of 44% (P-value¼2x10-54), with reduced cumulative incidences of IVD and IHD (Pvalues:0.009 and 0.05), and with corresponding risk reductions of, respectively, 41% [HR: 0.59 (0.41-0.86)] and 36% [HR: 0.64 (0.41-0.99)] (Pvalues:0.007 and 0.04). Conclusion: Loss-of-function mutations in APOC3 are associated with low levels of triglycerides, and with reduced risk of ischemic cardiovascular disease. This supports APOC3 inhibition as a novel therapeutic option. Genomics and proteomics of lipid metabolism EAS-0299. GENETIC DEFECTS IN PROTEIN GLYCOSYLATION AS A CAUSE OF DYSLIPIDEMIA M.A.W. van den Boogerta, S.D. Kuilb, G.K. Hovingha, M.M. Motazackera, J.H.M. Levelsa, G. Dallinga-Thiea, J.A. Kuivenhovenc, R. Weversb, E.S.G. Stroesa, D.J. Lefeberb, A.G. Hollebooma a
Vascular Medicine, Academic Medical Center, Amsterdam, Netherlands; Institute for Genetic & Metabolic Diseases, Radboud University Medical Center, Nijmegen, Netherlands; c Molecular Genetics, University Medical Center, Groningen, Netherlands b
Objectives: In most of our patients, we cannot reach adequate risk reduction with current treatments for dyslipidemia. This stresses the need for a more accurate understanding of lipid metabolism in order to identify novel
targets to improve our treatment. Recently our group described a genetic mutation in GALNT2 causing attenuated glycosylation of apoCIII and increased plasma HDL-cholesterol, demonstrating the first dyslipidemia caused by a genetic defect in the glycosylation of proteins. We hypothesized that other genetic disorders of glycosylation could lead to dyslipidemia as well. Methods: Firstly, genome-wide association studies (GWAS) were analyzed for links between glycosylation genes and plasma lipid levels. Secondly, a subgenome of genes known to be involved in congenital disorders of glycosylation (CDG) was analyzed in patients with extremely high and low HDL-cholesterol levels. Thirdly, lipid metabolism in patients with congenital disorders of glycosylation was studied. When a link was identified, a range of functional studies was performed to identify linking molecular mechanisms. Results: Firstly, GWAS linked variation in glycosylation genes GALNT2, B3GALT4 and B4GALT4 to plasma lipids. Secondly, we have identified multiple non-sense and missense variants in glycosylation genes in patients with extremely high and low HDL-cholesterol. Thirdly, we systematically analyzed 19 type 1 CDG patients (PMM2- and ALG6-CDG), and found decreased levels of total cholesterol, LDL-cholesterol and apolipoprotein B. Furthermore, we found strongly increased levels of HDLcholesterol, aberrantly glycosylated CETP and decreased CETP activity in type 2 CDG patients with a characterized genetic defect of a specific galactosyltransferase glycosylation enzyme, B4GalT1. Lastly, patients with CDG plus, caused by Golgi trafficking defects, consistently show extremely high levels of VLDL. Conclusion: In conclusion, our studies indicate specific physiological functions of protein glycosylation in lipid metabolism and may indicate completely novel targets for better treatment of dyslipidemia. Hypolidaemic drugs present and future EAS-0604. EFFECT OF ROSUVASTATIN THERAPY ON CAROTID INTIMA MEDIA THICKNESS IN CHILDREN WITH FAMILIAL HYPERCHOLESTEROLEMIA: FINDINGS FROM THE CHARON STUDY M.J.A.M. Braamskampa, G. Langsletb, B.W. McCrindlec, D. Cassimand, G.A. Francise, C. Gagnéf, D. Gaudetg, K.M. Morrisonh, A. Wiegmani, T. Turnerj, E. Millerk, J.S. Raichlenk, P.G. Martinl, E.A. Steinj, J.J.P. Kasteleinm a Department of Vascular Medicine and Department of Pediatrics, Academic Medical Center, Amsterdam, Netherlands; b Lipid Clinic Medical Clinic, Oslo University Hospital, Oslo, Norway; c Department of Pediatrics, University of Toronto, Toronto, Canada; d Department of Hepatology and Metabolic Center, University Hospitals Leuven, Leuven, Belgium; e Healthy Heart Program Prevention Clinical and Department of Medicine, University of British Columbia, Vancouver, Canada; f N/A, Clinique des maladies lipidiques de Québec, Québec, Canada; g Department of Medicine, Université de Montréal, Montréal, Canada; h Department of Pediatrics, McMaster University, Hamilton, Canada; i Department of Pediatrics, Academic Medical Center, Amsterdam, Netherlands; j N/A, Metabolic & Atherosclerosis Research Center, Cincinnati, USA; k Medicine & Science 1(CV), AstraZeneca LP, Wilmington, USA; l Biostatistics, AstraZeneca LP, Wilmington, USA; m Department of Vascular Medicine, Academic Medical Center, Amsterdam, Netherlands
Objectives: The aim of this study (NCT01078675) was to investigate the effect of rosuvastatin therapy on carotid intima media thickness (c-IMT) in children with familial hypercholesterolaemia (FH) aged 6–17 years compared with unaffected (non-FH) matched siblings. Methods: FH children with low-density lipoprotein cholesterol (LDL-C) >4.9 mmol/L or >4.1 mmol/L with other cardiovascular risk factors were included. 6–9 year olds were statin naïve. The children were treated with rosuvastatin 5 mg once daily, but could be up-titrated to 10 mg (6–9 years) or 20 mg (10–17 years) if an LDL-C target of Results: The intent-to-treat population included 197 FH children and 65 unaffected siblings. At baseline, the average mean c-IMT (mm) was higher for the FH children compared with the unaffected siblings (0.398 vs
Objectives: Atherosclerosis is a chronic lipid-driven inflammatory disease with a key role for macrophages. Epigenetic modifiers regulate DNA accessibility through histone modifications and fine-tune macrophage polarization. We hypothesized that targeting Hdac3 should offer a novel approach to confer atheroprotective mechanisms, since Hdac3 deletion elicits an anti-inflammatory macrophage phenotype. Methods: Bone marrow was isolated from LysMCre-Hdac3fl/fl mice (Hdac3del) and Hdac3fl/fl littermates (Hdac3wt) and transplanted to LDLR-/mice. Next we performed an in vivo foam cell formation experiment and assessed the mice during experimental atherosclerosis. Results: Pathway analysis of expression data indicated that Hdac3 deleted macrophages have enhanced PPARg and LXR signalling, implicating better lipid handling. Indeed, expression of LXR and PPARg target genes were upregulated and both in vivo and in vitro foam cell formation was reduced in Hdac3-deleted macrophages. In experimental atherosclerosis, we observed that macrophage Hdac3 deficiency resulted in slightly increased plaque size as a result of enhanced fibrosis, resulting in a two-fold thicker fibrous cap. We could confirm this in vitro by demonstrating that Hdac3deleted macrophages increased collagen production in isolated vascular smooth muscle cells. This was linked to an upregulation of TGFb expression in Hdac3 deleted macrophages, which was a consequence of the absence of Hdac3 repression on TGFb expression. Furthermore, examining human atherosclerotic samples we observed that Hdac3 gene expression is upregulated in unstable plaques, it colocalizes with pro-inflammatory M1 macrophages and that Hdac3 expression negatively correlates with TGFb expression. Conclusion: Here, we show that altering the macrophage’s epigenetic landscape through Hdac3 deletion changes the macrophage to a atherosclerosis-beneficial phenotype and thus may offer a novel manner for management of atherosclerosis. Supported by the Netherlands Heart Foundation (2013-T003 and 2007T067). Gene-environment interactions and epigenetics EAS-0760. IRON AS A RISK FACTOR FOR ATHEROSCLEROSIS: CONFIRMING THE IRON HYPOTHESIS IN A MOUSE MODEL OF HEMOCHROMATOSIS F. Vinchia, S. Altamuraa, M. Costa da Silvaa, B. Galya, M.W. Hentzea, M.U. Muckenthalera a Molecular Medicine Partnership Unit (MMPU), UniversitatsKlinikum Heidelberg & EMBL, Heidelberg, Germany
Objectives: Iron accumulates in atherosclerotic lesions but its role in atherogenesis is still debated. In 1981, Sullivan proposed the ’iron hypothesis’, according to which iron is detrimental for the cardiovascular system, thus promoting atherosclerosis progression. Epidemiological data and animal models have provided conflicting evidence regarding the role of iron in atherosclerosis. This project is aimed at elucidating whether iron contributes to atherosclerosis and at discriminating which iron source is involved in its pathogenesis. Methods: We applied a novel mouse model of type IV Hereditary Hemochromatosis to study the susceptibility to atherosclerosis. This disease is hallmarked by systemic iron overload and macrophage-iron deficiency, thus providing a way to dissect (1) the contribution of systemic iron overload to atherosclerosis, since these mice present with high transferrin saturation and NTBI levels; (2) the contribution of macrophage-retained iron, since these mice show macrophage iron deficiency. Results: In 3 month-old hemochromatotic mice, innominate artery lesion area is significantly smaller than in age-matched controls. This is accompanied by a reduction in oxLDL accumulation in the aorta. Conversely, at 6 months of age, the mice showed a more severe atherosclerotic phenotype,
e17
as suggested by the increased lesion size and number. This is associated with higher levels of circulating and aortic oxLDLs. Moreover, we observed an increased endothelial activation, as suggested by higher expression levels of adhesion molecules and increased levels of circulating soluble adhesion molecules. The vascular oxidative status is altered as indicated by the increased aortic lipid peroxidation and the upregulation of antioxidant genes. Conclusion: Collectively, these data suggest that macrophage-iron deple-
Ă
tion is protective for early atherosclerosis, while severe systemic iron overload promotes atherosclerosis progression, thus supporting the iron hypothesis. However, the protective effect of macrophage-iron depletion is not sufficient to counteract the strongly pro-atherogenic effect of high circulating iron. Genomics and proteomics of lipid metabolism EAS-0521. MUTATIONS IN STAP1 ARE ASSOCIATED WITH AUTOSOMAL DOMINANT HYPERCHOLESTEROLEMIA S.W. Fouchiera, N.O. Stitzielb, G.M. Dallinga-Thiec, J.C.M. Meijersa, N. Zelcerd, J.J.P. Kasteleinc, J.C. Defeschea, S. Kathiresane, G.K. Hovinghc a
Experimental Vascular Medicine, Academic Medical Center, Amsterdam, Netherlands; b Cardiovascular Medicine, Brigham and Women’s Hospital, Boston, USA; c Vascular Medicine, Academic Medical Center, Amsterdam, Netherlands; d Medical Biochemistry, Academic Medical Center, Amsterdam, Netherlands; e Program in Medical and Population Genetics, Broad Institute, Boston, USA Objectives: Autosomal Dominant Hypercholesterolemia (ADH) is caused by mutations in LDLR, APOB or PCSK9. A number of patients, however, suffer from “FH4”, defined as ADH in absence of mutations in these genes. Our aim was to identify the molecular pathology in a family suffering from FH4. Methods: Parametric linkage analysis combined with exome sequencing was carried out in 13 and 3 relatives, respectively. Identified variants were validated in 400 normolipidemic controls and 400 unrelated FH4 probands, and co-segregation with the ADH phenotype was assessed in families. Results: Linkage analysis revealed suggestive LOD scores of 2.99 (Q ¼ 0.0) at 4p15.1-q13.3, 11p13-q14.1, and 13q14.13-q32.1. The linked region on chromosome 4 harbored the variant, p.Glu97Asp in STAP1 (encoding signal transducing adaptor family member 1), associated with elevated plasma LDL-c in the family. STAP1 was sequenced in the FH4 cohort. A second proband carrying p.Glu97Asp and three additional probands carrying p.Leu69Ser, p.Ile71Thr, and p.Asp207Asn were identified. All variants altered highly conserved amino acid residues and were not present in controls. The prevalence of rare putative deleterious mutations in STAP1 was higher in our FH4 cohort (1.3%) compared to the publically available databases NHLBI-ESP (0.5%) and GoNL (0.2%). A disease penetrance of 0.9 was found while investigating the four variants in the five families. STAP1 carriers (N¼35) were younger (3819 vs. 4816 years; p<0.001), had higher plasma TC (6.521.52 vs. 5.761.25 mmol/l;
e18
Abstracts / Atherosclerosis 235 (2014) e11–e26
p<0.001) and LDL-c levels (4.261.22 vs. 3.831.10 mmol/l; p¼0.001) compared to non-affected relatives (N¼89). Conclusion: The prevalence of putative deleterious mutations in STAP1 is higher in FH4 subjects compared to controls and cholesterol levels are significantly elevated in carriers versus non-carriers. This suggest that STAP1 might play a role in cholesterol metabolism. Additional studies are warranted to address the biological mechanisms underlying the ADH phenotype in STAP1 mutation carriers. Genomics and proteomics of lipid metabolism EAS-0647. LOSS-OF-FUNCTION MUTATIONS IN APOC3 AND REDUCED RISK OF ISCHEMIC VASCULAR DISEASE A. Jørgensena, R. Frikke-Schmidta, B.G. Nordestgaardb, A. TybjærgHansena a
Department of Clinical Biochemistry, Rigshospitalet Copenhagen University Hospital, Copenhagen, Denmark; b Department of Clinical Biochemistry, Herlev Hospital Copenhagen University Hospital, Herlev, Denmark Objectives: High plasma levels of nonfasting triglycerides, a marker of high remnant cholesterol, are associated with increased risk of ischemic cardiovascular disease. Whether lifelong low levels of nonfasting triglycerides, due to mutations in APOC3, associate with reduced risk of ischemic cardiovascular disease in the general population is unknown. We tested this hypothesis. Methods: Using 75,725 individuals from the general population, we first tested whether low levels of nonfasting triglycerides were associated with reduced risk of ischemic vascular disease (IVD) and ischemic heart disease (IHD) in observational analyses. Second, whether loss-of-function mutations in APOC3 which were associated with reduced levels of nonfasting triglycerides, associated with reduced risk of IVD and IHD. During a median 4 and 34 years of follow-up, 5,410 and 10,797 individuals developed IVD in observational and genetic analyses, respectively. Results: In observational analyses, hazard ratios (HRs) for individuals with nonfasting triglycerides <1.00 mmol/L compared to >4.00 mmol/L, were 0.43(95% confidence interval, 0.35-0.54) for IVD and 0.40(0.31-0.52) for IHD. Corresponding HRs for individuals with nonfasting triglycerides in the lowest compared to the highest quintile were 0.55(0.47-0.65) and 0.49(0.40-0.59). Heterozygosity for loss-of-function mutations in APOC3 associated with mean reductions in plasma nonfasting triglycerides of 44% (P-value¼2x10-54), with reduced cumulative incidences of IVD and IHD (Pvalues:0.009 and 0.05), and with corresponding risk reductions of, respectively, 41% [HR: 0.59 (0.41-0.86)] and 36% [HR: 0.64 (0.41-0.99)] (Pvalues:0.007 and 0.04). Conclusion: Loss-of-function mutations in APOC3 are associated with low levels of triglycerides, and with reduced risk of ischemic cardiovascular disease. This supports APOC3 inhibition as a novel therapeutic option. Genomics and proteomics of lipid metabolism EAS-0299. GENETIC DEFECTS IN PROTEIN GLYCOSYLATION AS A CAUSE OF DYSLIPIDEMIA M.A.W. van den Boogerta, S.D. Kuilb, G.K. Hovingha, M.M. Motazackera, J.H.M. Levelsa, G. Dallinga-Thiea, J.A. Kuivenhovenc, R. Weversb, E.S.G. Stroesa, D.J. Lefeberb, A.G. Hollebooma a
Vascular Medicine, Academic Medical Center, Amsterdam, Netherlands; Institute for Genetic & Metabolic Diseases, Radboud University Medical Center, Nijmegen, Netherlands; c Molecular Genetics, University Medical Center, Groningen, Netherlands b
Objectives: In most of our patients, we cannot reach adequate risk reduction with current treatments for dyslipidemia. This stresses the need for a more accurate understanding of lipid metabolism in order to identify novel
targets to improve our treatment. Recently our group described a genetic mutation in GALNT2 causing attenuated glycosylation of apoCIII and increased plasma HDL-cholesterol, demonstrating the first dyslipidemia caused by a genetic defect in the glycosylation of proteins. We hypothesized that other genetic disorders of glycosylation could lead to dyslipidemia as well. Methods: Firstly, genome-wide association studies (GWAS) were analyzed for links between glycosylation genes and plasma lipid levels. Secondly, a subgenome of genes known to be involved in congenital disorders of glycosylation (CDG) was analyzed in patients with extremely high and low HDL-cholesterol levels. Thirdly, lipid metabolism in patients with congenital disorders of glycosylation was studied. When a link was identified, a range of functional studies was performed to identify linking molecular mechanisms. Results: Firstly, GWAS linked variation in glycosylation genes GALNT2, B3GALT4 and B4GALT4 to plasma lipids. Secondly, we have identified multiple non-sense and missense variants in glycosylation genes in patients with extremely high and low HDL-cholesterol. Thirdly, we systematically analyzed 19 type 1 CDG patients (PMM2- and ALG6-CDG), and found decreased levels of total cholesterol, LDL-cholesterol and apolipoprotein B. Furthermore, we found strongly increased levels of HDLcholesterol, aberrantly glycosylated CETP and decreased CETP activity in type 2 CDG patients with a characterized genetic defect of a specific galactosyltransferase glycosylation enzyme, B4GalT1. Lastly, patients with CDG plus, caused by Golgi trafficking defects, consistently show extremely high levels of VLDL. Conclusion: In conclusion, our studies indicate specific physiological functions of protein glycosylation in lipid metabolism and may indicate completely novel targets for better treatment of dyslipidemia. Hypolidaemic drugs present and future EAS-0604. EFFECT OF ROSUVASTATIN THERAPY ON CAROTID INTIMA MEDIA THICKNESS IN CHILDREN WITH FAMILIAL HYPERCHOLESTEROLEMIA: FINDINGS FROM THE CHARON STUDY M.J.A.M. Braamskampa, G. Langsletb, B.W. McCrindlec, D. Cassimand, G.A. Francise, C. Gagnéf, D. Gaudetg, K.M. Morrisonh, A. Wiegmani, T. Turnerj, E. Millerk, J.S. Raichlenk, P.G. Martinl, E.A. Steinj, J.J.P. Kasteleinm a Department of Vascular Medicine and Department of Pediatrics, Academic Medical Center, Amsterdam, Netherlands; b Lipid Clinic Medical Clinic, Oslo University Hospital, Oslo, Norway; c Department of Pediatrics, University of Toronto, Toronto, Canada; d Department of Hepatology and Metabolic Center, University Hospitals Leuven, Leuven, Belgium; e Healthy Heart Program Prevention Clinical and Department of Medicine, University of British Columbia, Vancouver, Canada; f N/A, Clinique des maladies lipidiques de Québec, Québec, Canada; g Department of Medicine, Université de Montréal, Montréal, Canada; h Department of Pediatrics, McMaster University, Hamilton, Canada; i Department of Pediatrics, Academic Medical Center, Amsterdam, Netherlands; j N/A, Metabolic & Atherosclerosis Research Center, Cincinnati, USA; k Medicine & Science 1(CV), AstraZeneca LP, Wilmington, USA; l Biostatistics, AstraZeneca LP, Wilmington, USA; m Department of Vascular Medicine, Academic Medical Center, Amsterdam, Netherlands
Objectives: The aim of this study (NCT01078675) was to investigate the effect of rosuvastatin therapy on carotid intima media thickness (c-IMT) in children with familial hypercholesterolaemia (FH) aged 6–17 years compared with unaffected (non-FH) matched siblings. Methods: FH children with low-density lipoprotein cholesterol (LDL-C) >4.9 mmol/L or >4.1 mmol/L with other cardiovascular risk factors were included. 6–9 year olds were statin naïve. The children were treated with rosuvastatin 5 mg once daily, but could be up-titrated to 10 mg (6–9 years) or 20 mg (10–17 years) if an LDL-C target of Results: The intent-to-treat population included 197 FH children and 65 unaffected siblings. At baseline, the average mean c-IMT (mm) was higher for the FH children compared with the unaffected siblings (0.398 vs