- Email: [email protected]
2WS08-5 Significance of insulin resistance to atherosclerosis
96
2WS08
Tuesday September 30, 2003: Workshop Obesity, Insulin Resistance and Atherosclerosis
stimulating factor (G-CSF), which mobilizes EPCs from bone marrow, could have a vasculogenic effect similar to that afforded by BMT. I. G-CSF treatment against ASO. A total of 44 individuals with intractable ASO (Fontaine III and IV) were randomly assigned into three groups. One month after the treatments, subjective symptoms improved significantly in the BMT group and in the G-CSF group(2-5 ug/kg/day for 10 days), compared with the control group. Ankle-brachial pressure index (ABPI) and transcutaneous oxygen pressure (TcO2 (mmHg)) increased similarly in the BMT group and in the G-CSF group, but not in the control group. II. G-CSF treatment against coronary heart disease. Twenty-two patients with intractable chronic coronary heart disease, which were not candidate for coronary intervention, were randomly assigned into 2 groups. In the G-CSF group, symptoms were improved in all patients. The %uptake in ischemic area was increased significantly after the treatment (63±11% to 71±11%). Extent score and severity score were significantly decreased after the treatment (extent score: 37±22 to 26±26; severity score: 51±52 to 33±44). In the control group, however, there were no significant differences in Tl-201 SPECT findings. Conclusions: G-CSF treatment improved clinical signs and symptoms of ASO and coronary heart disease via an increase of blood flow. This non-invasive treatment method should be used for the treatment of intractable ischemic arterial diseases.
2WS08 OBESITY, INSULIN RESISTANCE AND ATHEROSCLEROSIS 2WS08-1
Characterizing the metabolic syndrome trajectory: Key to prevention and treatment
B.C. Hansen. University of Maryland School of Medicine, USA The features of the Metabolic Syndrome, including most critically obesity and insulin resistance, develop over a long period in both humans and non human primates, and ultimately result in overt manifestations of Type 2 diabetes and/or cardiovascular disease. Early intervention depends upon an understanding of the trajectory or natural history of the development and the interactions of the various features with an aim toward identifying the earliest or optimal points for intervention, and the timing and targets for optimal treatment. Non human primates develop all of the features of the Metabolic Syndrome, including spontaneous middle age onset obesity, dyslipidemia with elevated triglycerides and reduced HDL cholesterol, hypertension, and impaired glucose tolerance. Using either environmental manipulations to prevent excess calorie intake and obesity or new and potential pharmacological approaches to mitigate obesity (weight reduction) and/or improve insulin sensitivity (PPAR agonists), we have shown in non human primates the critical role of adipose tissue mass and the endocrine products of the adipocyte in this Syndrome. These carefully controlled trials have shown both changes in gene expression and altered levels of the adipocytokines under these interventions. Evidence supports the pivotal and frequently permissive role of adipose tissue in the development of the complications of the metabolic syndrome, and the importance of adipose tissue as a target for successful intervention. 2WS08-2
PPARs control cell physiology and survival
W. Wahli, A. Tan, L. Michalik, N. Di-Poi, B. Desvergne. Center for Integrative Genomics, University of Lausanne, Switzerland The peroxisome proliferator activated receptors (PPARs) belong to the nuclear hormone receptor family. Upon binding to fatty acids or eicosanoids, PPARs stimulate the expression of target genes that are implicated in important metabolic pathways. PPARs have central roles in the storage and catabolism of fatty acids. PPAR-alpha and PPAR-gamma control energy homoeostasis and inflammatory responses. PPAR-beta has been implicated in reverse cholesterol transport, fat catabolism and in wound healing. In adult mouse interfollicular epidermis, PPAR-alpha and -beta expression is reactivated after various stimuli, resulting in keratinocyte proliferation and differentiation. The immediate response to a skin injury is the release of inflammatory cytokines. TNF-alpha induces the up-regulation of the PPAR-beta gene, which occurs via the stress-associated protein kinase cascade. Activated PPAR-beta stimulates Akt1 phosphorylation via transcriptional up-regulation of ILK and PDK1. The resulting higher Akt1 activity leads to increased keratinocyte survival. PPAR-beta also stimulates MMP-9 production, which
can regulate keratinocyte migration. The down regulation of PPAR-beta expression at the end of the wound healing process is most probably mediated through the TGF-beta signaling pathway known to regulate inflammatory responses, extracellular matrix deposition, cellular adhesion, migration and proliferation. Together, these results provide a molecular mechanism by which PPAR-beta protects cells against apoptosis and contributes to the process of wound closure. 2WS08-3
Alpha lipoic acid prevents the development of metabolic syndrome in OLETF rats
K. Lee. University of Ulsan College of Medicine, Seoul, Republic of Korea Objectives: Recent studies indicated that increased oxidative stress is related with metabolic syndrome. Alpha-lipoic acid (ALA) is a naturally occurring antioxidant with potent free radical scavenging activity. The present study was initiated to test possible preventive effects of alpha-lipoic acid on the development of metabolic syndrome in Otsuka Long Evans Tokushima Fatty (OLETF) rats. Methods: OLETF rats at 12 weeks of age were treated with or without ALA (0.5% of food weight) for 28 weeks. Results: Chronic administration of ALA (0.5% of food weight) profoundly reduced body weight gain and completely prevented the development of diabetes mellitus in OLETF rats. ALA reduced plasma levels of free fatty acid and triglyceride and also reduced triglyceride accumulation in skeletal muscle and pancreatic islets. ALA decreased blood pressure. Both endotheliumdependent and -independent vascular relaxations were impaired in OLETF rats. ALA treatment significantly improved endothelium-dependent vascular dysfunction in OLETF rats. Urinary nitric oxide (NO) excretion was lower in OLETF rats than in LETO rats, and was increased to the level of LETO rats by ALA treatment. Histological examination revealed that endothelial loss, along with increased endothelial cell apoptosis was evident in the blood vessel from OLETF rats, and that these findings were significantly improved in ALA-treated rats. Conclusions: Oxidative stress is causally related with the development of metabolic syndrome. ALA can be a new promising drug for the prevention/treatment of metabolic syndrome. 2WS08-4
Adipocytokine: Key player in metabolic syndrome
T. Funahashi 1 , S. Kihara 1 , Y. Matsuzawa 2 . 1 Department of Internal Medicine and Molecular Science; 2 Sumitomo Hospital, Japan The adipose tissues produce and secrete many bioactive substances, conceptualized as adipocytokines (Nature Medicine 1996). Dysregulated productions of adipocytokines lead to the development of metabolic syndrome. Adiponectin is an adipocytokine, which we identified by screening the adipose-specific genes from human fat. Adiponectin mRNA is expressed exclusively in adipose tissues. The adiponectin mRNAs and its plasma levels are reduced in obesity, type 2 diabetes and atherosclerosis. Hyperinsulinemic euglycemic clamp studies in human and monkey, and several recent studies using rodents revealed that adiponectin is an insulin-sensitizing hormone. Furthermore, adiponectin exhibited anti- atherogenic moieties on vascular endothelial cells, macrophages, and smooth muscle cells. The genetic mutation of the adiponectin gene accompanying hypoadiponectinemia was strongly associated with type 2 diabetes and atherosclerosis. The adiponectin knockout mice exhibited diet-induced diabetes and severer atherosclerotic response by vascular injury. We conclude that Hypoadiponectinemia stands at upstream of the pathophysiology of metabolic syndrome leading to atherosclerosis. Manipulation to increase the plasma levels and/or activity of adiponectin should become a new wave to tackle metabolic syndrome. 2WS08-5
Significance of insulin resistance to atherosclerosis
K. Higashiura. Sapporo Medical University, Japan Insulin resistance and compensatory hyperinsulinemia are recognized not only in obesity but also type 2 diabetes mellitus and essential hypertension. Recently, it has been reported that leptin relates to insulin resistance and hypertension, especially in obese subjects. Our epidemiological studies showed that the significant correlations were still kept between leptin and insulin sensitivity or blood pressure (BP), after adjustment for age and BMI, indicating that leptin correlates with insulin resistance and BP independently to BMI. To assess the existence of insulin resistance, we used a practical
XIIIth International Symposium on Atherosclerosis, September 28–October 2, 2003, Kyoto, Japan
Tuesday September 30, 2003: Workshop 2WS09 Thrombosis in Vascular Disease index, HOMA-R>1.73 is defined to have an insulin resistance. When residents of rural communities in Japan were followed for 8 years, the incidence of cardiovascular diseases (CVD) was significantly higher (1.6 fold) in subjects with insulin resistance than those without insulin resistance, after adjustment for age, BP and BMI. These findings suggest that insulin resistance is one of the major facilitation factors of genesis and progression of CVD. On the other hand, to examine the correlation of insulin resistance/hyperinsulinemia and atherosclerosis, we investigated the tissue specificity and intra cellular selectivity of insulin resistance in vasculature and skeletal muscle of fructosefed rats (FFR). There were no significant differences between extents of phosphorylation of ERK 1/2 by insulin in the thoracic aorta or soleus from control and FFR. Tyrosine phosphorylation of IRS-1 by insulin in the soleus from FFR was significantly reduced to 80% of the level that in control. These results suggest that IRS-1, PI-3 kinase pathway in skeletal muscle is selectively impaired in FFR, and this impairment may induce hyperinsulinemia, which stimulate MAPK pathway and leading to atherosclerosis. In conclusion, insulin resistance/hyperinsulinemia may be one of the mechanisms leading to atherosclerosis. 2WS08-6
Obesity and other risk factors for cardiovascular diseases among Africans: Results from CARDIAC study in Tanzania
M.A. Njelekela 1 , K. Ikeda 2 , J. Mtabaji 1 , Y. Yamori 3 . 1 Muhimbili University College of Health Sciences, Department of Physiology, Tanzania; 2 Mukogawa Womens University; 3 WHO Center for Primary Prevention of CVD, Japan
2WS09 THROMBOSIS IN VASCULAR DISEASE 2WS09-1
Megakaryocytes derived from embryonic stem cells implicate integrin αIIbβ3 signaling
K. Eto, S. Shattil. Scripps Research Institute, USA Platelet integrin αIIbβ3 is a key adhesion receptor in hemostasis and thrombosis. Ligand binding to αIIbβ3 is tightly regulated by “inside-out” signals that regulate integrin conformational changes (affinity) and clustering (avidity). In turn, ligand binding triggers “outside-in” signals that are required for efficient platelet adhesion and aggregation. However, the detailed mechanisms of integrin signaling in platelets remain to be defined. Since platelet are not amenable to genetic manipulation in vitro, our laboratory has utilized primary murine megakaryocytes as a model system to unravel mechanisms of integrin signaling relevant to platelet and other hematopoietc cells. In this context, we have recently obtained new experimental information to elucidate the mechanisms in which integrin αIIbβ3 is involved. First, we have developed a system whereby relatively large number of mature, proplatelet-producing megakaryocytes can be derived in culture from murine embryonic stem (ES) cells. Second, in gene profiling studies of primary megakaryocytes deficient in αIIbβ3 “inside-out” signaling, we have discovered several candidate genes potentially involved in this process. One of candidate genes was CalDAG-GEFI, a guanine nucleotide exchange factor for
Rap1b, small GTPase protein. At this workshop, I will primarily present the usefulness of ES cell-derived megakaryocytes to evaluate the role of candidate genes in integrin signaling as exemplified by CalDAG-GEFI. 2WS09-2
Anti-thrombotic and anti-inflammatory local gene therapy into injured arteries
H. Ueno. University of Occupational and Environmental Health, Scool of Medicine, Kitakyusyu, Japan It is clinically important to inhibit thrombosis and inflammation in atherosclerotic or balloon- and/or stent-treated arteries as a way of avoiding acute coronary syndrome. Since most anti-thrombotic agents, when administered systemically, can induce bleeding at locations far from their intended site of action, effective forms of local therapy are needed. Transfer of the genes of anti-thrombotic and anti-inflammatory molecules into injured arteries could be such a local therapy without distant bleeding. Three such molecules will be discussed: Tissue factor pathway inhibitor (TFPI), C-type natriuretic peptide (CNP), and Platelet-activating factor acethylhydrolase (PAF-AH). Adenovirus-mediated gene transfer of TFPI into injured arteries eliminates sheer stress-induced thrombosis even in the presence of epinephrine, without affecting systemic coagulation status. A combination of local irrigation with TFPI protein and TFPI gene transfer achieves a full coverage of tissue factor activity suppression, thereby enhancing their therapeutic effects. Overexpression of CNP increases NO production by enhancing the expression of inducible NO synthase. interestingly, the anti-thrombotic, anti-inflammatory, and antiproliferative effects of CNP are largely NO-dependent. Local expression of PAF-AH or angiopoietin-1 in non-hyperlipidemic animals also exert antiinflammatory and anti-thrombotic effects. Their effects are NO-independent. Searching for effective molecules and investigating their modes of action are important both for the selection of better candidates for future clinical application and to increase our understanding of the molecular mechanisms underlying arterial inflammation and thrombosis in vivo. 2WS09-3
Tissue factor as a therapeutic target
E. Tremoli 1 , M. Camera 2 , S. Colli 1 . 1 Department of Pharmacological Sciences, Milano; 2 Monzino Cardiology Center, Italy Tissue Factor (TF), a 47 Kd transmembrane glycoprotein, triggers the activation of the blood coagulation cascade that occurs in several human diseases such as sepsis and other systemic conditions. In addition, TF has been shown in atherosclerotic plaques. In particular TF protein and activity have been found to be increased in coronary plaques, thus playing a crucial role in human coronary syndromes. Several drugs are able to modulate TF expression, both in vitro and in vivo. In particular, statin treatment has been shown to significantly decrease TF expression in human carotid plaques. Vessel wall associated TF, however, does not entirely explain the thrombogenic potential of vascular lesions when they are exposed to the flowing blood. Experimental evidences suggest that arterial thrombosis is more greatly influenced by blood components than by elements within the arterial wall. On this regard it has been proposed that thrombus growth might be promoted by circulating (i.e. microparticles or platelet associated) TF. Recently it has been demonstrated that human platelets contain TF, probably derived from leucocytes. Data from our laboratory indicate that activation of platelets from healthy donors by platelet agonists such as ADP, TRAP and epinephrine induces TF expression on the cell surface in a time and concentration dependent manner. We also show that cell surface associated TF is functionally active since it binds human recombinant factor VIIa. Platelets do also contain measurable amount of TF mRNA. This suggest that these cells might be an additional source of the TF circulating pool and it may also contribute to the residual thrombogenicity of arterial thrombus. Thus platelets may be a source of circulating TF and ADP renders this protein available for the interaction with blood or vessel wall components, an event which may contribute to the growth of arterial thrombi. 2WS09-5
Homocysteine as a risk factor of cardiovascular disease
M. Merkel. University Hospital Hamburg Eppendorf, Germany Homocysteine is a product of methionine demethylation and a precursor for cysteine biosynthesis. Slight elevations in plasma homocysteine are frequently found in the general population. There is mounting evidence that moderate hyperhomocysteinemia is an independent risk factor for atherosclerosis and for venous thrombosis. Possible causes for hyperhomocysteinemia are
XIIIth International Symposium on Atherosclerosis, September 28–October 2, 2003, Kyoto, Japan
TUESDAY
Objective: The objective of this study was to investigate the prevalence of obesity and central adiposity and to assess if any significant relationship exists between obesity and other risk factors for CVD, in an African population. Methods: A cross sectional epidemiological study was conducted in three distinct areas; urban, rural and Masai population in Tanzania. Men and women aged 46-58y, were invited for the assessment of anthropometric measurements, BP, blood and 24h urine analysis and lifestyle questionnaire. A component of physical activity was evaluated by measuring resting energy expenditure (REE). Results: The overall prevalence of obesity (BMI>30kg/m2 ) was 14.2% and that of central of adiposity was 16.9%. Prevalence of smoking was still low, 24.1% of subjects were living a sedentary lifestyle, and 4.0% consumed alcohol at least daily. Of the obese subjects, 40.5% were categorized as educated and 59.1% lived in the urban area. Consumption of high calorie diet was common among obese people, meat (72.0%) and coconut milk (60.5%). Significant hypertension (48.1%), hypercholesterolemia (32.4%), hypertriglyceridemia (20.3%), elevated LDL-C (33.8%), and hyperglycemia (4.6%), was seen among obese subjects. Elevated plasma leptin concentration, and low mean REE were also observed among obese subjects. Conclusion: This study demonstrates that obesity associated with biochemical derangements is now a health problem in this African country. Effective strategies for primary prevention and treatment of obesity need to be introduced especially in the urban areas in Tanzania.
97
2WS08
Tuesday September 30, 2003: Workshop Obesity, Insulin Resistance and Atherosclerosis
stimulating factor (G-CSF), which mobilizes EPCs from bone marrow, could have a vasculogenic effect similar to that afforded by BMT. I. G-CSF treatment against ASO. A total of 44 individuals with intractable ASO (Fontaine III and IV) were randomly assigned into three groups. One month after the treatments, subjective symptoms improved significantly in the BMT group and in the G-CSF group(2-5 ug/kg/day for 10 days), compared with the control group. Ankle-brachial pressure index (ABPI) and transcutaneous oxygen pressure (TcO2 (mmHg)) increased similarly in the BMT group and in the G-CSF group, but not in the control group. II. G-CSF treatment against coronary heart disease. Twenty-two patients with intractable chronic coronary heart disease, which were not candidate for coronary intervention, were randomly assigned into 2 groups. In the G-CSF group, symptoms were improved in all patients. The %uptake in ischemic area was increased significantly after the treatment (63±11% to 71±11%). Extent score and severity score were significantly decreased after the treatment (extent score: 37±22 to 26±26; severity score: 51±52 to 33±44). In the control group, however, there were no significant differences in Tl-201 SPECT findings. Conclusions: G-CSF treatment improved clinical signs and symptoms of ASO and coronary heart disease via an increase of blood flow. This non-invasive treatment method should be used for the treatment of intractable ischemic arterial diseases.
2WS08 OBESITY, INSULIN RESISTANCE AND ATHEROSCLEROSIS 2WS08-1
Characterizing the metabolic syndrome trajectory: Key to prevention and treatment
B.C. Hansen. University of Maryland School of Medicine, USA The features of the Metabolic Syndrome, including most critically obesity and insulin resistance, develop over a long period in both humans and non human primates, and ultimately result in overt manifestations of Type 2 diabetes and/or cardiovascular disease. Early intervention depends upon an understanding of the trajectory or natural history of the development and the interactions of the various features with an aim toward identifying the earliest or optimal points for intervention, and the timing and targets for optimal treatment. Non human primates develop all of the features of the Metabolic Syndrome, including spontaneous middle age onset obesity, dyslipidemia with elevated triglycerides and reduced HDL cholesterol, hypertension, and impaired glucose tolerance. Using either environmental manipulations to prevent excess calorie intake and obesity or new and potential pharmacological approaches to mitigate obesity (weight reduction) and/or improve insulin sensitivity (PPAR agonists), we have shown in non human primates the critical role of adipose tissue mass and the endocrine products of the adipocyte in this Syndrome. These carefully controlled trials have shown both changes in gene expression and altered levels of the adipocytokines under these interventions. Evidence supports the pivotal and frequently permissive role of adipose tissue in the development of the complications of the metabolic syndrome, and the importance of adipose tissue as a target for successful intervention. 2WS08-2
PPARs control cell physiology and survival
W. Wahli, A. Tan, L. Michalik, N. Di-Poi, B. Desvergne. Center for Integrative Genomics, University of Lausanne, Switzerland The peroxisome proliferator activated receptors (PPARs) belong to the nuclear hormone receptor family. Upon binding to fatty acids or eicosanoids, PPARs stimulate the expression of target genes that are implicated in important metabolic pathways. PPARs have central roles in the storage and catabolism of fatty acids. PPAR-alpha and PPAR-gamma control energy homoeostasis and inflammatory responses. PPAR-beta has been implicated in reverse cholesterol transport, fat catabolism and in wound healing. In adult mouse interfollicular epidermis, PPAR-alpha and -beta expression is reactivated after various stimuli, resulting in keratinocyte proliferation and differentiation. The immediate response to a skin injury is the release of inflammatory cytokines. TNF-alpha induces the up-regulation of the PPAR-beta gene, which occurs via the stress-associated protein kinase cascade. Activated PPAR-beta stimulates Akt1 phosphorylation via transcriptional up-regulation of ILK and PDK1. The resulting higher Akt1 activity leads to increased keratinocyte survival. PPAR-beta also stimulates MMP-9 production, which
can regulate keratinocyte migration. The down regulation of PPAR-beta expression at the end of the wound healing process is most probably mediated through the TGF-beta signaling pathway known to regulate inflammatory responses, extracellular matrix deposition, cellular adhesion, migration and proliferation. Together, these results provide a molecular mechanism by which PPAR-beta protects cells against apoptosis and contributes to the process of wound closure. 2WS08-3
Alpha lipoic acid prevents the development of metabolic syndrome in OLETF rats
K. Lee. University of Ulsan College of Medicine, Seoul, Republic of Korea Objectives: Recent studies indicated that increased oxidative stress is related with metabolic syndrome. Alpha-lipoic acid (ALA) is a naturally occurring antioxidant with potent free radical scavenging activity. The present study was initiated to test possible preventive effects of alpha-lipoic acid on the development of metabolic syndrome in Otsuka Long Evans Tokushima Fatty (OLETF) rats. Methods: OLETF rats at 12 weeks of age were treated with or without ALA (0.5% of food weight) for 28 weeks. Results: Chronic administration of ALA (0.5% of food weight) profoundly reduced body weight gain and completely prevented the development of diabetes mellitus in OLETF rats. ALA reduced plasma levels of free fatty acid and triglyceride and also reduced triglyceride accumulation in skeletal muscle and pancreatic islets. ALA decreased blood pressure. Both endotheliumdependent and -independent vascular relaxations were impaired in OLETF rats. ALA treatment significantly improved endothelium-dependent vascular dysfunction in OLETF rats. Urinary nitric oxide (NO) excretion was lower in OLETF rats than in LETO rats, and was increased to the level of LETO rats by ALA treatment. Histological examination revealed that endothelial loss, along with increased endothelial cell apoptosis was evident in the blood vessel from OLETF rats, and that these findings were significantly improved in ALA-treated rats. Conclusions: Oxidative stress is causally related with the development of metabolic syndrome. ALA can be a new promising drug for the prevention/treatment of metabolic syndrome. 2WS08-4
Adipocytokine: Key player in metabolic syndrome
T. Funahashi 1 , S. Kihara 1 , Y. Matsuzawa 2 . 1 Department of Internal Medicine and Molecular Science; 2 Sumitomo Hospital, Japan The adipose tissues produce and secrete many bioactive substances, conceptualized as adipocytokines (Nature Medicine 1996). Dysregulated productions of adipocytokines lead to the development of metabolic syndrome. Adiponectin is an adipocytokine, which we identified by screening the adipose-specific genes from human fat. Adiponectin mRNA is expressed exclusively in adipose tissues. The adiponectin mRNAs and its plasma levels are reduced in obesity, type 2 diabetes and atherosclerosis. Hyperinsulinemic euglycemic clamp studies in human and monkey, and several recent studies using rodents revealed that adiponectin is an insulin-sensitizing hormone. Furthermore, adiponectin exhibited anti- atherogenic moieties on vascular endothelial cells, macrophages, and smooth muscle cells. The genetic mutation of the adiponectin gene accompanying hypoadiponectinemia was strongly associated with type 2 diabetes and atherosclerosis. The adiponectin knockout mice exhibited diet-induced diabetes and severer atherosclerotic response by vascular injury. We conclude that Hypoadiponectinemia stands at upstream of the pathophysiology of metabolic syndrome leading to atherosclerosis. Manipulation to increase the plasma levels and/or activity of adiponectin should become a new wave to tackle metabolic syndrome. 2WS08-5
Significance of insulin resistance to atherosclerosis
K. Higashiura. Sapporo Medical University, Japan Insulin resistance and compensatory hyperinsulinemia are recognized not only in obesity but also type 2 diabetes mellitus and essential hypertension. Recently, it has been reported that leptin relates to insulin resistance and hypertension, especially in obese subjects. Our epidemiological studies showed that the significant correlations were still kept between leptin and insulin sensitivity or blood pressure (BP), after adjustment for age and BMI, indicating that leptin correlates with insulin resistance and BP independently to BMI. To assess the existence of insulin resistance, we used a practical
XIIIth International Symposium on Atherosclerosis, September 28–October 2, 2003, Kyoto, Japan
Tuesday September 30, 2003: Workshop 2WS09 Thrombosis in Vascular Disease index, HOMA-R>1.73 is defined to have an insulin resistance. When residents of rural communities in Japan were followed for 8 years, the incidence of cardiovascular diseases (CVD) was significantly higher (1.6 fold) in subjects with insulin resistance than those without insulin resistance, after adjustment for age, BP and BMI. These findings suggest that insulin resistance is one of the major facilitation factors of genesis and progression of CVD. On the other hand, to examine the correlation of insulin resistance/hyperinsulinemia and atherosclerosis, we investigated the tissue specificity and intra cellular selectivity of insulin resistance in vasculature and skeletal muscle of fructosefed rats (FFR). There were no significant differences between extents of phosphorylation of ERK 1/2 by insulin in the thoracic aorta or soleus from control and FFR. Tyrosine phosphorylation of IRS-1 by insulin in the soleus from FFR was significantly reduced to 80% of the level that in control. These results suggest that IRS-1, PI-3 kinase pathway in skeletal muscle is selectively impaired in FFR, and this impairment may induce hyperinsulinemia, which stimulate MAPK pathway and leading to atherosclerosis. In conclusion, insulin resistance/hyperinsulinemia may be one of the mechanisms leading to atherosclerosis. 2WS08-6
Obesity and other risk factors for cardiovascular diseases among Africans: Results from CARDIAC study in Tanzania
M.A. Njelekela 1 , K. Ikeda 2 , J. Mtabaji 1 , Y. Yamori 3 . 1 Muhimbili University College of Health Sciences, Department of Physiology, Tanzania; 2 Mukogawa Womens University; 3 WHO Center for Primary Prevention of CVD, Japan
2WS09 THROMBOSIS IN VASCULAR DISEASE 2WS09-1
Megakaryocytes derived from embryonic stem cells implicate integrin αIIbβ3 signaling
K. Eto, S. Shattil. Scripps Research Institute, USA Platelet integrin αIIbβ3 is a key adhesion receptor in hemostasis and thrombosis. Ligand binding to αIIbβ3 is tightly regulated by “inside-out” signals that regulate integrin conformational changes (affinity) and clustering (avidity). In turn, ligand binding triggers “outside-in” signals that are required for efficient platelet adhesion and aggregation. However, the detailed mechanisms of integrin signaling in platelets remain to be defined. Since platelet are not amenable to genetic manipulation in vitro, our laboratory has utilized primary murine megakaryocytes as a model system to unravel mechanisms of integrin signaling relevant to platelet and other hematopoietc cells. In this context, we have recently obtained new experimental information to elucidate the mechanisms in which integrin αIIbβ3 is involved. First, we have developed a system whereby relatively large number of mature, proplatelet-producing megakaryocytes can be derived in culture from murine embryonic stem (ES) cells. Second, in gene profiling studies of primary megakaryocytes deficient in αIIbβ3 “inside-out” signaling, we have discovered several candidate genes potentially involved in this process. One of candidate genes was CalDAG-GEFI, a guanine nucleotide exchange factor for
Rap1b, small GTPase protein. At this workshop, I will primarily present the usefulness of ES cell-derived megakaryocytes to evaluate the role of candidate genes in integrin signaling as exemplified by CalDAG-GEFI. 2WS09-2
Anti-thrombotic and anti-inflammatory local gene therapy into injured arteries
H. Ueno. University of Occupational and Environmental Health, Scool of Medicine, Kitakyusyu, Japan It is clinically important to inhibit thrombosis and inflammation in atherosclerotic or balloon- and/or stent-treated arteries as a way of avoiding acute coronary syndrome. Since most anti-thrombotic agents, when administered systemically, can induce bleeding at locations far from their intended site of action, effective forms of local therapy are needed. Transfer of the genes of anti-thrombotic and anti-inflammatory molecules into injured arteries could be such a local therapy without distant bleeding. Three such molecules will be discussed: Tissue factor pathway inhibitor (TFPI), C-type natriuretic peptide (CNP), and Platelet-activating factor acethylhydrolase (PAF-AH). Adenovirus-mediated gene transfer of TFPI into injured arteries eliminates sheer stress-induced thrombosis even in the presence of epinephrine, without affecting systemic coagulation status. A combination of local irrigation with TFPI protein and TFPI gene transfer achieves a full coverage of tissue factor activity suppression, thereby enhancing their therapeutic effects. Overexpression of CNP increases NO production by enhancing the expression of inducible NO synthase. interestingly, the anti-thrombotic, anti-inflammatory, and antiproliferative effects of CNP are largely NO-dependent. Local expression of PAF-AH or angiopoietin-1 in non-hyperlipidemic animals also exert antiinflammatory and anti-thrombotic effects. Their effects are NO-independent. Searching for effective molecules and investigating their modes of action are important both for the selection of better candidates for future clinical application and to increase our understanding of the molecular mechanisms underlying arterial inflammation and thrombosis in vivo. 2WS09-3
Tissue factor as a therapeutic target
E. Tremoli 1 , M. Camera 2 , S. Colli 1 . 1 Department of Pharmacological Sciences, Milano; 2 Monzino Cardiology Center, Italy Tissue Factor (TF), a 47 Kd transmembrane glycoprotein, triggers the activation of the blood coagulation cascade that occurs in several human diseases such as sepsis and other systemic conditions. In addition, TF has been shown in atherosclerotic plaques. In particular TF protein and activity have been found to be increased in coronary plaques, thus playing a crucial role in human coronary syndromes. Several drugs are able to modulate TF expression, both in vitro and in vivo. In particular, statin treatment has been shown to significantly decrease TF expression in human carotid plaques. Vessel wall associated TF, however, does not entirely explain the thrombogenic potential of vascular lesions when they are exposed to the flowing blood. Experimental evidences suggest that arterial thrombosis is more greatly influenced by blood components than by elements within the arterial wall. On this regard it has been proposed that thrombus growth might be promoted by circulating (i.e. microparticles or platelet associated) TF. Recently it has been demonstrated that human platelets contain TF, probably derived from leucocytes. Data from our laboratory indicate that activation of platelets from healthy donors by platelet agonists such as ADP, TRAP and epinephrine induces TF expression on the cell surface in a time and concentration dependent manner. We also show that cell surface associated TF is functionally active since it binds human recombinant factor VIIa. Platelets do also contain measurable amount of TF mRNA. This suggest that these cells might be an additional source of the TF circulating pool and it may also contribute to the residual thrombogenicity of arterial thrombus. Thus platelets may be a source of circulating TF and ADP renders this protein available for the interaction with blood or vessel wall components, an event which may contribute to the growth of arterial thrombi. 2WS09-5
Homocysteine as a risk factor of cardiovascular disease
M. Merkel. University Hospital Hamburg Eppendorf, Germany Homocysteine is a product of methionine demethylation and a precursor for cysteine biosynthesis. Slight elevations in plasma homocysteine are frequently found in the general population. There is mounting evidence that moderate hyperhomocysteinemia is an independent risk factor for atherosclerosis and for venous thrombosis. Possible causes for hyperhomocysteinemia are
XIIIth International Symposium on Atherosclerosis, September 28–October 2, 2003, Kyoto, Japan
TUESDAY
Objective: The objective of this study was to investigate the prevalence of obesity and central adiposity and to assess if any significant relationship exists between obesity and other risk factors for CVD, in an African population. Methods: A cross sectional epidemiological study was conducted in three distinct areas; urban, rural and Masai population in Tanzania. Men and women aged 46-58y, were invited for the assessment of anthropometric measurements, BP, blood and 24h urine analysis and lifestyle questionnaire. A component of physical activity was evaluated by measuring resting energy expenditure (REE). Results: The overall prevalence of obesity (BMI>30kg/m2 ) was 14.2% and that of central of adiposity was 16.9%. Prevalence of smoking was still low, 24.1% of subjects were living a sedentary lifestyle, and 4.0% consumed alcohol at least daily. Of the obese subjects, 40.5% were categorized as educated and 59.1% lived in the urban area. Consumption of high calorie diet was common among obese people, meat (72.0%) and coconut milk (60.5%). Significant hypertension (48.1%), hypercholesterolemia (32.4%), hypertriglyceridemia (20.3%), elevated LDL-C (33.8%), and hyperglycemia (4.6%), was seen among obese subjects. Elevated plasma leptin concentration, and low mean REE were also observed among obese subjects. Conclusion: This study demonstrates that obesity associated with biochemical derangements is now a health problem in this African country. Effective strategies for primary prevention and treatment of obesity need to be introduced especially in the urban areas in Tanzania.
97