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GLIMEPIRIDE ENHANCES APOA-I- AND HDL-MEDIATED CHOLESTEROL EFFLUX FROM THP-1 MACROPHAGES BY INCREASING ABCA1, ABCG1 AND SR-BI EXPRESSION
42 PO10-100
Poster Sessions PO11 Receptors and signaling pathways in lipid metabolism IMPACT OF TRANSCRIPTION-FACTOR 7-LIKE (TCF7L2) GENE-VARIANTS ON THE RESPONSE TO ANTI-HYPERGLYCAEMIC TREATMENT IN NON-OBESE PATIENTS WITH TYPE-2 DIABETES (T2DM)
S.S. Lund 1 , L. Tarnow 1 , C. Stehouwer 2 , C.G. Schalkwijk 2,3 , M. Frandsen 1 , U.M. Smidt 1 , T. Hansen 1 , O. Pedersen 1 , H.-H. Parving 4 , A.A. Vaag 1 . 1 Steno Diabetes Center, Gentofte, Denmark; 2 Department of Internal Medicine, University Hospital Maastrict, Maastrict, Netherlands; 3 Department of Clinical Chemistry, VU University Medical Centre, Amsterdam, Netherlands; 4 University of Copenhagen, Rigshospitalet, Copenhagen, Denmark Background/Aims: Common TCF7L2 gene-variants have been associated with T2DM (rs7903146 and rs12255372) and obesity (rs10885406). We studied the impact of TCF7L2 gene-variants on glucose lowering (HbA1c) and anti-inflammatory (hsCRP) efficacy of metformin or repaglinide targeting insulin-resistance and insulin-secretion, respectively, in non-obese T2DM-patients. Methods: Randomised, double-masked, 2 x 4 months cross-over-study of metformin 1g twice-daily versus repaglinide 2 mg thrice-daily in 96 non-obese (BMI ≤27 kg/m2 ) insulin-naïve Caucasian T2DM-patients (rs10885406: AA: n=17; AG: n=60; GG: n=19; rs7903146: TT: n=8; TC: n=58; CC: n=30; rs12255372: GG: n=36; GT: n=55; TT: n=5). Results: Compared with AA-homozygotes, rs10885406 G-allele carriers had lower HbA1c during metformin treatment (Mean [SE] HbA1cdifference during metformin: G-allele carriers versus AA-homozygotes: -0.52% [0.23], p=0.026). Likewise, during metformin versus repaglinide treatments, hsCRP levels were lower in rs10885406 G-allele carriers and in rs12255372 T-allele carriers (Mean [SE] percentage difference in hsCRP metformin versus repaglinide, rs10885406 G-allel-carriers: -26.0% [11.2]; p=0.028; rs12255372 T-allele carriers: -31.5% [12.5]; p=0.018, respectively). Furthermore, compared with AA-homozygotes, rs10885406 G-allele carriers had increased hsCRP levels during repaglinide treatment (Mean [SE] difference in hsCRP during repaglinide, rs10885406 G-allele carriers versus AA-homozygotes: 76.2% [33.6], p=0.021). Treatment-byTCF7L2-genotype (rs10885406 or rs12255372) interaction was significant for hsCRP (p=0.029 and p=0.046, respectively), but not for HbA1c. The rs7903146 TCF7L2 gene-variant did not influence treatment responses. Conclusions: In non-obese T2DM-patients, common TCF7L2 genevariants might influence glycaemic and non-glycaemic responses to anti-hyperglycaemic treatment. Metformin may have improved glycaemic and/or anti-inflammatory effects in rs10885406 G-allele and rs12255372 T-allele carriers, whereas repaglinide may have improved anti-inflammatory effects in rs10885406 AA-homozygotes. PO10-101
COMPARISON OF EFFECTS OF TORCETRAPIB AND RO4607381/JTT-705 ON BLOOD PRESSURE AND TISSUE EXPRESSION OF RENIN-ANGIOTENSIN SYSTEM-RELATED GENES IN RATS
J.J. Kastelein 1 , E.S. Stroes 1 , A. Benardeau 2 , D. Blum 2 , R.G. Clerc 2 , L. Campos 2 , E.J. Niesor 2 . 1 Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; 2 F. Hoffmann-La Roche Ltd, Basel, Switzerland Background and aims: The cholesteryl ester transfer protein (CETP) inhibitor torcetrapib has been associated with increases in blood pressure (BP) and cardiovascular events. To investigate whether this is a compound or class effect we compared the haemodynamic effects of torcetrapib and RO4607381/JTT-705 in a rat model which enabled direct comparison of off-target toxicity by CETP inhibitors. Methods: Mean arterial pressure (AP), systolic AP, diastolic AP, and heart rate were measured by telemetry in normotensive and spontaneously hypertensive (SH) rats receiving torcetrapib 10, 40 or 80 mg/kg/day; RO4607381/JTT-705 100, 300 or 500 mg/kg/day; or vehicle for 5 days. Renin-angiotensin system (RAS) gene mRNA levels were measured by quantitative PCR in tissue samples (adrenal glands, kidneys, aorta, lung) collected from normotensive rats on day 5 to investigate the expression of genes involved in BP regulation. Results: Torcetrapib administration transiently increased BP in normotensive rats (+5 mmHg), and dose-dependently increased mean, systolic and diastolic APs in SH rats, with mean AP increases (+7 to +11 mmHg with torcetrapib 40 mg/kg/day [p<0.05 versus placebo]) maintained over
the treatment period. Heart rate did not change. RO4607381/JTT-705 did not change BP or heart rate. Increased RAS-related gene expression was observed with torcetrapib but not RO4607381/JTT-705 treatment. Conclusions: In rats, torcetrapib increased BP with a concomitant increase in RAS-related gene expression, whereas RO4607381/JTT-705 had no impact. This illustrates the off-target toxicity of torcetrapib which does not apply to RO4607381/JTT-705. Further studies are required to evaluate the effects of other CETP inhibitors on BP and gene expression.
PO11 RECEPTORS AND SIGNALING PATHWAYS IN LIPID METABOLISM PO11-102
GLIMEPIRIDE ENHANCES APOA-I- AND HDL-MEDIATED CHOLESTEROL EFFLUX FROM THP-1 MACROPHAGES BY INCREASING ABCA1, ABCG1 AND SR-BI EXPRESSION
M. Ogura, M. Ayaori, K. Nakaya, E. Yakushiji, S. Takiguchi, M. Kusuhara, F. Ohsuzu. Internal Medicine, National Defense Medical College, Tokorozawa, Saitama, Japan [Aim] The ATP binding cassette transporters A1 and G1 (ABCA1/G1) and scavenger receptor class B type I (SR-BI) are key molecules in cholesterol efflux and anti-atherogenesis. Sulfonylurea (SU) agents, glibenclamide (Glib) and glimepiride (Glim), are widely used oral hypoglycemic drugs. Glib is known as an effective inhibitor of ABCA1 and to abolish apolipoprotein A-I (apoA-I)-mediated cholesterol efflux. The aim of this study is to investigate whether Glim and Glib affect cholesterol efflux and ABCA1/G1 and SR-BI expression in THP-1 macrophages. [Methods and Results] Glib increased ABCA1 protein levels in THP-1 macrophages at a concentration of 1 or 10 µM; in contrast, dramatically decreased at 100 µM, which reportedly exhibits complete abolishment of apoA-Imediated cholesterol efflux. Glib treatment at a concentration of 1-10 µM and 100 µM respectively increased and markedly decreased ABCG1 and SR-BI protein levels. In contrast, Glim increased ABCA1, ABCG1 and SR-BI protein levels in a dose-dependent manner up to 100 µM. Mirroring the protein levels, Glim and Glib respectively increased and decreased both apoA-I- and HDL-mediated cholesterol efflux from THP-1 macrophages in a dose-dependent manner. Glim induced a slight increase in ABCA1/G1 and SR-BI mRNA levels. Glib at low (1-10 µM) and high concentrations (100µM) respectively increased and unchanged ABCA1/G1 and SR-BI mRNA levels. [Conclusion] Glim enhanced both apoA-I- and HDL-mediated cholesterol efflux from THP-1 macrophages by increasing ABCA1/G1 and SR-BI expression in contrast to Glib. The effects of Glim and Glib on protein expression of these molecules might be mediated through posttranslational regulation. PO11-103
THE HDL RECEPTOR SR-BI PLAYS AN IMPORTANT ROLE IN INFLAMMATION AND PROTECTS AGAINST ENDOTOXEMIA IN MICE
L. Cai 1,2 , A. Ji 1,2 , Y. Li 1,2 , F. de Beer 1,2 , L. Tannock 1,2 , D. van der westhuyzen 1,2 . 1 Division of Endocrinology and Molecular Medicine, Department of Internal Medicine, Cardiovascular Research Center and Graduate Center of Nutritional Sciences, University of Kentucky Medical Center, Lexington, Kentucky, 40536, USA; 2 Veterans Affairs Medical Center, Lexington, Kentucky, 40536, USA Background and aims: Scavenger receptor BI (SR-BI), an HDL receptor, plays a key role in reverse cholesterol transport. Disruption of SR-BI increases atherosclerotic lesion formation in several mouse models. However, liver specific SR-BI-deficiency in mice results in significantly less atherosclerosis compared to whole-body SR-BI-deficiency, indicating an extra-hepatic protective effect(s) of SR-BI. In this study, we identify an anti-inflammatory role of SR-BI. Methods: The survival and inflammatory response to lipopolysaccharide (LPS) was investigated in SR-BI-null mice. Peritoneal and bone marrow derived macrophages were isolated for in vitro studies. Results: Despite elevated plasma HDL levels, SR-BI-null mice displayed a markedly enhanced inflammatory cytokine response and a markedly higher lethality rate than control mice in response to LPS. SR-BInull mice showed a lack of inducible glucocorticoid synthesis in response to LPS, bacterial infection, stress or ACTH. Glucocorticoid insufficiency
77th Congress of the European Atherosclerosis Society, April 26–29, 2008, Istanbul, Turkey
Poster Sessions PO11 Receptors and signaling pathways in lipid metabolism IMPACT OF TRANSCRIPTION-FACTOR 7-LIKE (TCF7L2) GENE-VARIANTS ON THE RESPONSE TO ANTI-HYPERGLYCAEMIC TREATMENT IN NON-OBESE PATIENTS WITH TYPE-2 DIABETES (T2DM)
S.S. Lund 1 , L. Tarnow 1 , C. Stehouwer 2 , C.G. Schalkwijk 2,3 , M. Frandsen 1 , U.M. Smidt 1 , T. Hansen 1 , O. Pedersen 1 , H.-H. Parving 4 , A.A. Vaag 1 . 1 Steno Diabetes Center, Gentofte, Denmark; 2 Department of Internal Medicine, University Hospital Maastrict, Maastrict, Netherlands; 3 Department of Clinical Chemistry, VU University Medical Centre, Amsterdam, Netherlands; 4 University of Copenhagen, Rigshospitalet, Copenhagen, Denmark Background/Aims: Common TCF7L2 gene-variants have been associated with T2DM (rs7903146 and rs12255372) and obesity (rs10885406). We studied the impact of TCF7L2 gene-variants on glucose lowering (HbA1c) and anti-inflammatory (hsCRP) efficacy of metformin or repaglinide targeting insulin-resistance and insulin-secretion, respectively, in non-obese T2DM-patients. Methods: Randomised, double-masked, 2 x 4 months cross-over-study of metformin 1g twice-daily versus repaglinide 2 mg thrice-daily in 96 non-obese (BMI ≤27 kg/m2 ) insulin-naïve Caucasian T2DM-patients (rs10885406: AA: n=17; AG: n=60; GG: n=19; rs7903146: TT: n=8; TC: n=58; CC: n=30; rs12255372: GG: n=36; GT: n=55; TT: n=5). Results: Compared with AA-homozygotes, rs10885406 G-allele carriers had lower HbA1c during metformin treatment (Mean [SE] HbA1cdifference during metformin: G-allele carriers versus AA-homozygotes: -0.52% [0.23], p=0.026). Likewise, during metformin versus repaglinide treatments, hsCRP levels were lower in rs10885406 G-allele carriers and in rs12255372 T-allele carriers (Mean [SE] percentage difference in hsCRP metformin versus repaglinide, rs10885406 G-allel-carriers: -26.0% [11.2]; p=0.028; rs12255372 T-allele carriers: -31.5% [12.5]; p=0.018, respectively). Furthermore, compared with AA-homozygotes, rs10885406 G-allele carriers had increased hsCRP levels during repaglinide treatment (Mean [SE] difference in hsCRP during repaglinide, rs10885406 G-allele carriers versus AA-homozygotes: 76.2% [33.6], p=0.021). Treatment-byTCF7L2-genotype (rs10885406 or rs12255372) interaction was significant for hsCRP (p=0.029 and p=0.046, respectively), but not for HbA1c. The rs7903146 TCF7L2 gene-variant did not influence treatment responses. Conclusions: In non-obese T2DM-patients, common TCF7L2 genevariants might influence glycaemic and non-glycaemic responses to anti-hyperglycaemic treatment. Metformin may have improved glycaemic and/or anti-inflammatory effects in rs10885406 G-allele and rs12255372 T-allele carriers, whereas repaglinide may have improved anti-inflammatory effects in rs10885406 AA-homozygotes. PO10-101
COMPARISON OF EFFECTS OF TORCETRAPIB AND RO4607381/JTT-705 ON BLOOD PRESSURE AND TISSUE EXPRESSION OF RENIN-ANGIOTENSIN SYSTEM-RELATED GENES IN RATS
J.J. Kastelein 1 , E.S. Stroes 1 , A. Benardeau 2 , D. Blum 2 , R.G. Clerc 2 , L. Campos 2 , E.J. Niesor 2 . 1 Department of Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; 2 F. Hoffmann-La Roche Ltd, Basel, Switzerland Background and aims: The cholesteryl ester transfer protein (CETP) inhibitor torcetrapib has been associated with increases in blood pressure (BP) and cardiovascular events. To investigate whether this is a compound or class effect we compared the haemodynamic effects of torcetrapib and RO4607381/JTT-705 in a rat model which enabled direct comparison of off-target toxicity by CETP inhibitors. Methods: Mean arterial pressure (AP), systolic AP, diastolic AP, and heart rate were measured by telemetry in normotensive and spontaneously hypertensive (SH) rats receiving torcetrapib 10, 40 or 80 mg/kg/day; RO4607381/JTT-705 100, 300 or 500 mg/kg/day; or vehicle for 5 days. Renin-angiotensin system (RAS) gene mRNA levels were measured by quantitative PCR in tissue samples (adrenal glands, kidneys, aorta, lung) collected from normotensive rats on day 5 to investigate the expression of genes involved in BP regulation. Results: Torcetrapib administration transiently increased BP in normotensive rats (+5 mmHg), and dose-dependently increased mean, systolic and diastolic APs in SH rats, with mean AP increases (+7 to +11 mmHg with torcetrapib 40 mg/kg/day [p<0.05 versus placebo]) maintained over
the treatment period. Heart rate did not change. RO4607381/JTT-705 did not change BP or heart rate. Increased RAS-related gene expression was observed with torcetrapib but not RO4607381/JTT-705 treatment. Conclusions: In rats, torcetrapib increased BP with a concomitant increase in RAS-related gene expression, whereas RO4607381/JTT-705 had no impact. This illustrates the off-target toxicity of torcetrapib which does not apply to RO4607381/JTT-705. Further studies are required to evaluate the effects of other CETP inhibitors on BP and gene expression.
PO11 RECEPTORS AND SIGNALING PATHWAYS IN LIPID METABOLISM PO11-102
GLIMEPIRIDE ENHANCES APOA-I- AND HDL-MEDIATED CHOLESTEROL EFFLUX FROM THP-1 MACROPHAGES BY INCREASING ABCA1, ABCG1 AND SR-BI EXPRESSION
M. Ogura, M. Ayaori, K. Nakaya, E. Yakushiji, S. Takiguchi, M. Kusuhara, F. Ohsuzu. Internal Medicine, National Defense Medical College, Tokorozawa, Saitama, Japan [Aim] The ATP binding cassette transporters A1 and G1 (ABCA1/G1) and scavenger receptor class B type I (SR-BI) are key molecules in cholesterol efflux and anti-atherogenesis. Sulfonylurea (SU) agents, glibenclamide (Glib) and glimepiride (Glim), are widely used oral hypoglycemic drugs. Glib is known as an effective inhibitor of ABCA1 and to abolish apolipoprotein A-I (apoA-I)-mediated cholesterol efflux. The aim of this study is to investigate whether Glim and Glib affect cholesterol efflux and ABCA1/G1 and SR-BI expression in THP-1 macrophages. [Methods and Results] Glib increased ABCA1 protein levels in THP-1 macrophages at a concentration of 1 or 10 µM; in contrast, dramatically decreased at 100 µM, which reportedly exhibits complete abolishment of apoA-Imediated cholesterol efflux. Glib treatment at a concentration of 1-10 µM and 100 µM respectively increased and markedly decreased ABCG1 and SR-BI protein levels. In contrast, Glim increased ABCA1, ABCG1 and SR-BI protein levels in a dose-dependent manner up to 100 µM. Mirroring the protein levels, Glim and Glib respectively increased and decreased both apoA-I- and HDL-mediated cholesterol efflux from THP-1 macrophages in a dose-dependent manner. Glim induced a slight increase in ABCA1/G1 and SR-BI mRNA levels. Glib at low (1-10 µM) and high concentrations (100µM) respectively increased and unchanged ABCA1/G1 and SR-BI mRNA levels. [Conclusion] Glim enhanced both apoA-I- and HDL-mediated cholesterol efflux from THP-1 macrophages by increasing ABCA1/G1 and SR-BI expression in contrast to Glib. The effects of Glim and Glib on protein expression of these molecules might be mediated through posttranslational regulation. PO11-103
THE HDL RECEPTOR SR-BI PLAYS AN IMPORTANT ROLE IN INFLAMMATION AND PROTECTS AGAINST ENDOTOXEMIA IN MICE
L. Cai 1,2 , A. Ji 1,2 , Y. Li 1,2 , F. de Beer 1,2 , L. Tannock 1,2 , D. van der westhuyzen 1,2 . 1 Division of Endocrinology and Molecular Medicine, Department of Internal Medicine, Cardiovascular Research Center and Graduate Center of Nutritional Sciences, University of Kentucky Medical Center, Lexington, Kentucky, 40536, USA; 2 Veterans Affairs Medical Center, Lexington, Kentucky, 40536, USA Background and aims: Scavenger receptor BI (SR-BI), an HDL receptor, plays a key role in reverse cholesterol transport. Disruption of SR-BI increases atherosclerotic lesion formation in several mouse models. However, liver specific SR-BI-deficiency in mice results in significantly less atherosclerosis compared to whole-body SR-BI-deficiency, indicating an extra-hepatic protective effect(s) of SR-BI. In this study, we identify an anti-inflammatory role of SR-BI. Methods: The survival and inflammatory response to lipopolysaccharide (LPS) was investigated in SR-BI-null mice. Peritoneal and bone marrow derived macrophages were isolated for in vitro studies. Results: Despite elevated plasma HDL levels, SR-BI-null mice displayed a markedly enhanced inflammatory cytokine response and a markedly higher lethality rate than control mice in response to LPS. SR-BInull mice showed a lack of inducible glucocorticoid synthesis in response to LPS, bacterial infection, stress or ACTH. Glucocorticoid insufficiency
77th Congress of the European Atherosclerosis Society, April 26–29, 2008, Istanbul, Turkey