- Email: [email protected]
Contrasting effects of AT1 and AT2 antagonism on angiotensin II induced atherosclerosis and abdominal aortic aneurysms
Wednesday June 28, 2000: Workshop Abstracts W:24 Hormones and Cardiovascular Disease
166
IWeW4.23
Human vascular smooth muscle cells express an
endogenous inhibitor of Caspase-1
U. Schiinbeck, J.L. Young, G.K. Sukhova, P. Libby. Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
Objective: Caspase-1 regulates key steps in inflammation and immunity, by either activating the pro-inflammatory cytokines IL-lbeta and IL-l 8 or mediating apoptosis, processes associated with the chronic inflammatory disease, atherosclerosis. We recently provided evidence for the regulation of Caspase-1 activity via an endogenous inhibitor expressed by human vascular smooth muscle cells @MC). However, the molecular identity of this endogenous inhibitor remained undefined, rendering Caspase- 1 inhibitors restricted to either synthetic peptides or viral proteins. Methods and Results: We report here, that the serine proteinase inhibitor (Serpin) PI-9 accounts for the endogenous Caspasel inhibitory activity in human SMC and prevents processing of the natural substrates, IL-lbeta and IL-18 precursor, as determined by Western blot analysis. Treatment of SMC lysates with anti-PI-9 antibody abrogated the Caspase-1 inhibitory activity and co-precipitated the enzyme, demonstrating protein-protein interaction. Furthermore, PI-9 antisense oligonucleotides coordinately reduced PI-9 expression and promoted IL-lbeta release. Since SMC comprise the majority of cells in the vascular wall, and Caspase-1 and IL-l are firmly implicated in atherogenesis, we tested the biological validity of our findings within human atheroma in situ. The unaffected arterial wall contains abundant, homogeneously distributed, PI-9. In human atherosclerotic lesions, however, PI-9 expression correlated inversely with immunoreactive IL-lbeta, supporting a potential role of the endogenous Caspase-1 inhibitor in this chronic inflammatory disease. Conclusions: Our results provide new insights into the regulation of Caspase-1, an enzyme involved in immune and inllammatoty processes of chronic inflammatory diseases, and point to an endogenous anti-intlammatory action of PI-9, dysregulated in the human prevalent disease, atherosclerosis. WeW5.23 EII
Contrasting effects of AT1 and AT2 antagonism on angiotensin II induced atherosclerosis and abdominal aortic aneurysms
Alan Dauahertv,
Lisa Cassis. University of Kentucky, Lexington, KE USA
Objective: Previously,
we have demonstrated that infusion of angiotensin II (AngII) into apolipoprotein E-/mice leads to the rapid formation of atherosclerotic lesions and development of abdominal aortic aneurysms (AAA). The aim of the present study was to define the effects of specific AngIl receptor antagonism on the development of vascular pathology. Methods: Mature apoE -/mice were infused via osmotic pumps for 28 days with either an AT1 (losartan, 30 m&g/day) or AT2 (PD 123319, 3 mg/kg/day) antagonist, either alone, or with combined administration of AngII (1 &kg/mm). Results: AngIl infusion increased the extent of atherosclerosis and generated AAA in 70% on mice. Losartan totally ablated me AngII induced atherosclerosis and AAA. PD123319 failed to influence me AngII induced development of atherosclerosis. However, it increased the incidence of aneurysms to 100%. Furthermore, the aneurysms formed were larger and had a more complex appearance. Administration of losartan or PD123319, in the absence of AngII infusion, had no effect on the development of atherosclerotic lesions or AAA. Conclusion: AT1 receptor antagonism profoundly decreased AngII induced vascular pathology, while blockade of AT2 receptors unexpectedly promoted effects on AAA.
m
WeW6 23
Anti-atherosclerotic effect of SB-244323, a lipoprotein associated pbosphoilpase A2 inhibitor, in WHHL rabbits
G.M. Benson’, D. Grimsditch’,K. Milliner’, K. Moores’, H. Boyd*, D. Tew*. D. Hicke$.. R. Ife3. K. Sucklina’. C. Macnhee’ Departments of ‘Vascular Biology; 2Molecular Recognitt%n; 3Medi&al Chemistry, _ SmithKline Beecham Pharmaceuticals, NFSP(N), Harlow, Essex, UK Lipoprotein associated pbospholipase AZ (Lp-PLA& PAF-acetylhydrolase, is expressed by macrophages in atherosclerotic lesions and is responsible for generating significant quantities of the pro-inflammatory mediator lyso-PC during the oxidation of LDL. We therefore investigated the potential anti-atherogenic properties of the potent Lp-PLA2 inhibitor SB-244323 (ethyl ester pro-drug of SB-245713, ICso = 8 nM) in WHHL rabbits. A dose of compound was selected that reduced aortic Lp-PLAz activity to that observed in aortas of
normal NZW rabbits. Male WHHL rabbits (n = 2l/grp) were treated with 20 umolkgld of SB-244323 in the diet or diet alone for 12 weeks. The rabbits were then killed, their aortas were removed and the atherosclerotic lesions were measured and characterised. SB-244323 reduced Lp-PLAz activity in rabbit plasma and aortas by 99% and 54%, respectively, and there were no adverse reactions to treatment. Whereas plasma lipids were unaffected by treatment, concentrations of plasma PAI- were significantly reduced by 41% by SB-244323 after 6 weeks of treatment. The total cross-sectional area, thickness and macrophage content of aortic atherosclerotic lesions were measured in histological sections. Treatment reduced all parameters measured with larger lesions; SB 244323 reduced median lesion cross-sectional area and thickness significantly by 38% and 24% respectively in sections taken from just below the coeliac artery. Conclusion: These results support the view that Lp-PLA2 plays a significant role in the development of atherosclerotic plaque.
IWeW7.23
Adoptive transfer of b2giycoprotein I (b2GPI)-reactive lymphocyte enhances atherosclerosis in LDL receptor deficient mice
D. Harats J. George, B. Gilburd, A. Afek, A. Shaish, Y. Shoenfeld. Institute -3 of Lipid and Atherosclerosis Research, Sheba Medical Center Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Israel
Background: It has been proposed that autoimmune factors can influence the progression of atherosclerosis. We have previously shown that immunization of LDL-receptor deficient (LDL-RD mice) with b2 glycopotein I (b2GPI; a principal target of ‘autoimmune’ anti-phospholipid antibodies) enhances early atherosclerosis. In the current study we tested the hypothesis that adoptive transfer of b2GPI reactive T-cells can accelerate atherogenesis in LDL-RD mice. Methods and Results: LDL-RD mice were immunized with human b2GPI. An additional group of mice were immunized with b2GPI and boosted with the same antigen 3 weeks later. Control mice with immunized with human serum albumin (HSA). Lymphocytes obtained from the draining lymph-node cells or from splenocytes of h2GPI or HSA immunized mice were stimulated in-vitro with b2GPI or with the mitogen Concavaline A, respectively. The cultured lymphocytes were transferred intraperiteneally to syngenic LDL-RD mice and fed for 5 weeks a high-fat ‘Western’ diet until sacrifice. Mice injected with lymphocytes from draining lymph nodes or spleens of b2GPI-immunized animals displayed larger atherosclerotic lesions as compared to those induced by control treated animals. T-cell depleted splenocytes from b2GPI were unable to promote lesion formation in the mice. Lymphocytes that mediated lesion enhancement displayed a predominant T helper 1 phenotype evident by increased secretion of g interferon in-vitro priming with b2GPI. Conclusion: This is the first direct evidence for a role of antigen (bZGPI)reactive T cells in promoting atherosclerotic lesions in mice.
w:Z4
HORMONES
AND CARDIOVASCULAR DISEASE
WeWl.24 A cilnicai overview with focus on growth hormone L__.L-l K.J. Osterziel. Franz-Volhard-KliniUCharite, Humboldt University of Berlin, Germany Ischemic and dilated cardiomyopathies am characterized by ventricular dilatation, thin ventricular walls and impaired systolic function. Recently, it could be shown that the activity of the somatotrophic system is decreased in heart failure. Cardiac cachexia is characterized by low IGF-I. The decrease of insulin-like growth factor I (IGF-I), one of the mediators of growth hormone (GH) effects, correlates to left ventricular ejection fraction and inversely to left ventricular size. Subtle, yet unknown alterations of the somatotrophic system may lead to the decrease of serum IGF-I levels. Several pilot studies have shown hemodynamic and clinical improvement after treatment with human recombinant growth hormone (GH) for 3 months. Larger randomized, double-blind and placebo-controlled trials could not confirm the expected clinical improvement. A subgroup of patients showed hemodynamic improvement, most likely due to an increased NO-formation. The significant increase of myocardial mass by GH was related to the increase of IGF-I. When IGF-I increased by more than 80 pg/ml a significant increse of ejection fraction could be shown.
XIIth International Symposium on Atherosclerosis, Stockholm, Sweden, June 25-29, 2000
166
IWeW4.23
Human vascular smooth muscle cells express an
endogenous inhibitor of Caspase-1
U. Schiinbeck, J.L. Young, G.K. Sukhova, P. Libby. Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
Objective: Caspase-1 regulates key steps in inflammation and immunity, by either activating the pro-inflammatory cytokines IL-lbeta and IL-l 8 or mediating apoptosis, processes associated with the chronic inflammatory disease, atherosclerosis. We recently provided evidence for the regulation of Caspase-1 activity via an endogenous inhibitor expressed by human vascular smooth muscle cells @MC). However, the molecular identity of this endogenous inhibitor remained undefined, rendering Caspase- 1 inhibitors restricted to either synthetic peptides or viral proteins. Methods and Results: We report here, that the serine proteinase inhibitor (Serpin) PI-9 accounts for the endogenous Caspasel inhibitory activity in human SMC and prevents processing of the natural substrates, IL-lbeta and IL-18 precursor, as determined by Western blot analysis. Treatment of SMC lysates with anti-PI-9 antibody abrogated the Caspase-1 inhibitory activity and co-precipitated the enzyme, demonstrating protein-protein interaction. Furthermore, PI-9 antisense oligonucleotides coordinately reduced PI-9 expression and promoted IL-lbeta release. Since SMC comprise the majority of cells in the vascular wall, and Caspase-1 and IL-l are firmly implicated in atherogenesis, we tested the biological validity of our findings within human atheroma in situ. The unaffected arterial wall contains abundant, homogeneously distributed, PI-9. In human atherosclerotic lesions, however, PI-9 expression correlated inversely with immunoreactive IL-lbeta, supporting a potential role of the endogenous Caspase-1 inhibitor in this chronic inflammatory disease. Conclusions: Our results provide new insights into the regulation of Caspase-1, an enzyme involved in immune and inllammatoty processes of chronic inflammatory diseases, and point to an endogenous anti-intlammatory action of PI-9, dysregulated in the human prevalent disease, atherosclerosis. WeW5.23 EII
Contrasting effects of AT1 and AT2 antagonism on angiotensin II induced atherosclerosis and abdominal aortic aneurysms
Alan Dauahertv,
Lisa Cassis. University of Kentucky, Lexington, KE USA
Objective: Previously,
we have demonstrated that infusion of angiotensin II (AngII) into apolipoprotein E-/mice leads to the rapid formation of atherosclerotic lesions and development of abdominal aortic aneurysms (AAA). The aim of the present study was to define the effects of specific AngIl receptor antagonism on the development of vascular pathology. Methods: Mature apoE -/mice were infused via osmotic pumps for 28 days with either an AT1 (losartan, 30 m&g/day) or AT2 (PD 123319, 3 mg/kg/day) antagonist, either alone, or with combined administration of AngII (1 &kg/mm). Results: AngIl infusion increased the extent of atherosclerosis and generated AAA in 70% on mice. Losartan totally ablated me AngII induced atherosclerosis and AAA. PD123319 failed to influence me AngII induced development of atherosclerosis. However, it increased the incidence of aneurysms to 100%. Furthermore, the aneurysms formed were larger and had a more complex appearance. Administration of losartan or PD123319, in the absence of AngII infusion, had no effect on the development of atherosclerotic lesions or AAA. Conclusion: AT1 receptor antagonism profoundly decreased AngII induced vascular pathology, while blockade of AT2 receptors unexpectedly promoted effects on AAA.
m
WeW6 23
Anti-atherosclerotic effect of SB-244323, a lipoprotein associated pbosphoilpase A2 inhibitor, in WHHL rabbits
G.M. Benson’, D. Grimsditch’,K. Milliner’, K. Moores’, H. Boyd*, D. Tew*. D. Hicke$.. R. Ife3. K. Sucklina’. C. Macnhee’ Departments of ‘Vascular Biology; 2Molecular Recognitt%n; 3Medi&al Chemistry, _ SmithKline Beecham Pharmaceuticals, NFSP(N), Harlow, Essex, UK Lipoprotein associated pbospholipase AZ (Lp-PLA& PAF-acetylhydrolase, is expressed by macrophages in atherosclerotic lesions and is responsible for generating significant quantities of the pro-inflammatory mediator lyso-PC during the oxidation of LDL. We therefore investigated the potential anti-atherogenic properties of the potent Lp-PLA2 inhibitor SB-244323 (ethyl ester pro-drug of SB-245713, ICso = 8 nM) in WHHL rabbits. A dose of compound was selected that reduced aortic Lp-PLAz activity to that observed in aortas of
normal NZW rabbits. Male WHHL rabbits (n = 2l/grp) were treated with 20 umolkgld of SB-244323 in the diet or diet alone for 12 weeks. The rabbits were then killed, their aortas were removed and the atherosclerotic lesions were measured and characterised. SB-244323 reduced Lp-PLAz activity in rabbit plasma and aortas by 99% and 54%, respectively, and there were no adverse reactions to treatment. Whereas plasma lipids were unaffected by treatment, concentrations of plasma PAI- were significantly reduced by 41% by SB-244323 after 6 weeks of treatment. The total cross-sectional area, thickness and macrophage content of aortic atherosclerotic lesions were measured in histological sections. Treatment reduced all parameters measured with larger lesions; SB 244323 reduced median lesion cross-sectional area and thickness significantly by 38% and 24% respectively in sections taken from just below the coeliac artery. Conclusion: These results support the view that Lp-PLA2 plays a significant role in the development of atherosclerotic plaque.
IWeW7.23
Adoptive transfer of b2giycoprotein I (b2GPI)-reactive lymphocyte enhances atherosclerosis in LDL receptor deficient mice
D. Harats J. George, B. Gilburd, A. Afek, A. Shaish, Y. Shoenfeld. Institute -3 of Lipid and Atherosclerosis Research, Sheba Medical Center Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Israel
Background: It has been proposed that autoimmune factors can influence the progression of atherosclerosis. We have previously shown that immunization of LDL-receptor deficient (LDL-RD mice) with b2 glycopotein I (b2GPI; a principal target of ‘autoimmune’ anti-phospholipid antibodies) enhances early atherosclerosis. In the current study we tested the hypothesis that adoptive transfer of b2GPI reactive T-cells can accelerate atherogenesis in LDL-RD mice. Methods and Results: LDL-RD mice were immunized with human b2GPI. An additional group of mice were immunized with b2GPI and boosted with the same antigen 3 weeks later. Control mice with immunized with human serum albumin (HSA). Lymphocytes obtained from the draining lymph-node cells or from splenocytes of h2GPI or HSA immunized mice were stimulated in-vitro with b2GPI or with the mitogen Concavaline A, respectively. The cultured lymphocytes were transferred intraperiteneally to syngenic LDL-RD mice and fed for 5 weeks a high-fat ‘Western’ diet until sacrifice. Mice injected with lymphocytes from draining lymph nodes or spleens of b2GPI-immunized animals displayed larger atherosclerotic lesions as compared to those induced by control treated animals. T-cell depleted splenocytes from b2GPI were unable to promote lesion formation in the mice. Lymphocytes that mediated lesion enhancement displayed a predominant T helper 1 phenotype evident by increased secretion of g interferon in-vitro priming with b2GPI. Conclusion: This is the first direct evidence for a role of antigen (bZGPI)reactive T cells in promoting atherosclerotic lesions in mice.
w:Z4
HORMONES
AND CARDIOVASCULAR DISEASE
WeWl.24 A cilnicai overview with focus on growth hormone L__.L-l K.J. Osterziel. Franz-Volhard-KliniUCharite, Humboldt University of Berlin, Germany Ischemic and dilated cardiomyopathies am characterized by ventricular dilatation, thin ventricular walls and impaired systolic function. Recently, it could be shown that the activity of the somatotrophic system is decreased in heart failure. Cardiac cachexia is characterized by low IGF-I. The decrease of insulin-like growth factor I (IGF-I), one of the mediators of growth hormone (GH) effects, correlates to left ventricular ejection fraction and inversely to left ventricular size. Subtle, yet unknown alterations of the somatotrophic system may lead to the decrease of serum IGF-I levels. Several pilot studies have shown hemodynamic and clinical improvement after treatment with human recombinant growth hormone (GH) for 3 months. Larger randomized, double-blind and placebo-controlled trials could not confirm the expected clinical improvement. A subgroup of patients showed hemodynamic improvement, most likely due to an increased NO-formation. The significant increase of myocardial mass by GH was related to the increase of IGF-I. When IGF-I increased by more than 80 pg/ml a significant increse of ejection fraction could be shown.
XIIth International Symposium on Atherosclerosis, Stockholm, Sweden, June 25-29, 2000