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Cytokine regulation of vascular nitric oxide synthases: Implications in atherosclerosis
Frulav. 28 May 1999 WorL~'hop: Triglyceride-rich lipoproteins and atherosclerosis active there and infection with this LPS containing gram-negative obligatory intracellular bacterium is known to result in oxidative processes and induction of cytokines, adhesion molecules, and proteolytic enzymes. f_'ross-reactivity of chlamydial hsp 60 with human hsp 60 and chlamydial Lmter membrane protein 2 with heart ct myosin can lead to autoimmunity. Moreover, alterations arc seen in lipid profiles of chronically infected hosts; namely rise in triglyceride concentrations and decrease of HDL levels. ~?hronic C. pneumoniae infection seems to be a risk factor also in familiar hyperchotesteremia. C. pneumoniae -positive atherosc~erotic plaques have recently been produced in intranasally infected experimental animals on aormal diet, suggesting that it is able to initiate the process. The formation of these lesions can, moreover, be prevented by antibiotic treatment. In humans. first preliminary intervention trials with rr]acrolide or azalide antibiotic, ~lthough quite small in scale, have also been successful in two of three cases, leading to significant decrease in cardiac re-events, Large-scale secondary ~ntervention trials have just started. Drug therapy effective against chlamydia ms also been recently reported to associate with lowered risk for primary :ardiac event. There is even a possibility, that after some years antibiotics :an be added in the current armature of antiatherosclerotic drugs. At this alomenl, however, we do not know, which patients could benefit from mtichlamydial antibiotics, how we could find them, and what would then 9e the proper treatment. INCREASED ACUTE PHASE REACTANTS ARE ASSOCIATED WITH INCREASED LEVELS OF T R I G L Y C E R I D E - R I C H LIPOPROTEINS, AND INCREASED C A R O T I D PLAQUE VOLUME
3.G. Nordestgaard, M.-L.M. Gronholdt, H. Laursen, H. Sillesen. Unicetwity 71Copenhagen. Denmark Fhis study tested the hypotheses that increased acute phase reactants predict :levated levels of triglyceride-rich lipoproteins, increased plaque volume as xell as echolucency of carotid plaques. The study included 258 patients xith >50°0 carotid artery stenosis. Acute phase reactants (orosomucoid, C•eacti~e protein, CRP) were measured in the fasting state, and lipoproteins ~efure and alter a standardized fatty meal. Echogenicity of carotid plaques xas evaluated using high-resolution B-mode ultrasound and computerlssisted image processing. A subgroup of 81 patients underwent carotid ;ndarterectomy. On linear regression analysis, orosomucoid levels were ~ositively associated with (I) lasting and postprandial levels of plasma riglyccrides, (2) intermediate densily lipoprotein triglycerides, (3) very low tensity lipoprotein/chylomicron remnant cholesterol and triglycerides, and 4) with the area under the plasma triglyceride curve 0 to 4 hours after a atty meal (all p-values < 0.0001 ); results for CRP were less pronounced. On nuhivariate analysis these results were confirmed. Orosomucoid and CRP )redicted the presence of an increased carotid plaque volume on univariate malysis (p = 0.01 and p = 0.02L however, only orosomucoid remained t predictor on multivariate analysis (p = 0.02). Finally, orosomucoid was ~egatively associated with echolucency of carotid plaques (p = 0.05). In :onclusion, increased acute phase reactants are associated with increased )lasma levels of triglyceride-rich lipoproteins. Furthermore, acute phase reactants predict an increased plaque volume and possibly plaque echolucency. ~IEMBRANE PROTEINS OF CHLAMYDIA PNEUMONIAE INDUCE ['HE S E C R E T I O N OF 92-kDa GELATINASE BY HUMAN ~IONOCYTE-DERIVED M A C R O P H A G E S
Vehmaan-Kreula t M. Puolakkainen 2, M. Sarvas 3, H.G. Welgus4, ~.T. Kovanen 1 . /Wihuri Research Institute. Kaltiolinnantie 4. Hetsinki; 'Department of Virology. Haartmaninkatu 3. Uniuersi~ o]" Helsinki." ~National Public Health Institute. Helsinki. Finland: 4Division of )ermatolog); Department of Medicine. Washington UnioersiO, School of ffedicine. St. Louis. USA dacrophages, mast cells and T-lymphocytes are the principal inflammatory :ell types of atherosclerotic lesions in human coronary atheromas. The nacrophages secrete matrix metalloproteinases (MMP's) which are capable )f degrading the extracellular matrix (ECM) components. In advanced ~therosclerotic lesions, sometimes can be found Chtamydia pneumoniae ~acteria. Here we have studied in vitro the ability of human monoeyte-derived nacrophages to secrete interstitial collagenase, stromelysin, 92-kDa gelatirose, and their inhibitor TIMP as a response to stimulation with Chlamytia pneumoniae. The metalloproteinase content of the monocyte-derived nacrophage supernatants was quantified by ELISA. We found that Chlamvfia pneumoniae induced the secretion of 92-kDa gelatinase but not of
87
interstitial collagenase, stromelysin or TIME We also found that induction of 92-kDa gelatinase production by C. pneumoniae acts throught its membrane proteins HSP 60, MOMP, and Omp 2, but not through its lipopolysaccharide component. The results show that C. pneumoniae induce secretion of an ECM-degrading enzyme, and so could contribute to the destabilization and rupture of atherosclerotic lesions.
C Y T O K I N E REGULATION OF VASCULAR NITRIC OXIDE SYNTHASES: IMPLICATIONS IN ATHEROSCLEROSIS
J.D. Catravas. Vascular Biolog), Center, Medical College of Georgia, Augusta. Georgia. USA The vessel wall is the locus of two isozymes of nitric oxide synthase (NOS): a largely constitutive type III (in endothelial cells) and a mostly inducible type I1 (in smooth muscle ceils). Small amounts of NO are tonically released by the constitutive type 111 NOS via a calcium-sensitive mechanism and are important contributors to the endothelial anti-inflammatory functions, including inhibition of endothelial - leukocyte interactions. Conversely, large amounts of NO are produced by type 11 NOS in response to various cytokines, via a calicum-independent mechanism and serve a proinflammatory function. Monocytes are early participants in the pathogenesis of atberosclerosis and a source of cytokines, including interleukin-I (IL-I). IL-I is not only a potent inducer of type It NOS, but also appears to downregulate type I11 NOS. Mechanisms of monocyte- and cytokine- mediated regulation of both NOS isozymes will be discussed.
-f Workshop: Triglyceride-rich lipoproteins and atherosclerosis REMNANTS OF POSTPRANDIAL T R I G L Y C E R I D E - R I C H LIPOPROTEINS AND ATHEROSCLEROSIS
E Karpe 1, S. Boquist 1, A. [,arsson l, A. Hamsten 1, A. Syv~nne2, M.-R. Taskinen2. /King Gustaf V Research Institute. Karolinska Hospital,
S-171 76 Stockholm. Sweden." 2Dept. of Medicine. UniuersiO, Hospital. 00029 Helsinki. Finland Recent studies suggest that VLDL metabolism is delayed and altered in the postprandial state. This is likely to lead to enhanced cholesteryl ester transfer protein-mediated exchange of cholesterol and triglycerides between HDL and VLDL. Recently, a novel method based on immunoaffinity separation of plasma for determination of remnant-like lipoproteins (RLP) has been developed. Interestingly, the compositional characteristics described for RLP are very similar to that of postprandially modified VLDL, i.e. cholesterol and apoE enrichment. It was therefore of interest to investigate the relationship between plasma levels of RLP cholesterol in both early and late stages of cardiovascular disease. First, a group of 91 healthy male 50-year old subjects homozygous for apoE3 was enrolled in a study of prognostic markers o f early atherosclerotic signs defined as an increased intima-media (IM) thickness analysed in the far wall of the carotid artery by B-mode ultrasound. Several parameters correlated significantly with carotid IM thickening, of those the strongest were: LDL r = 0.24, p < 0.05 and RLP r = 0.30, p < 0.01. All significant variables from a univariate statistical analysis were entered into a multiple stepwise regression analysis. RLP first entered the equation and explained 8% of the variability (r z = 0.08) the carotid IM thickness, independent of both LDL cholesterol plasma triglycerides. Second, RLP cholesterol levels were quantified in a 2-year double-blind, placebo-controlled angiographic study of gemfibrozil treatment including patients with low HDL cholesterol and a recent procedure of coronary artery bypass grafting, i.e. the Lopid Coronary Angiography Trial (LOCAT). Gemfibrozil treatment reduced RLP cholesterol by approximately 30%. The on-treatment level of RLP cholesterol was significantly associated with reduced progression of the minimum lumen diameter (p < 0.01 ) and a very signifcant effect was seen on the occurrence of new lesions in vein gratis. Subjects with 1 new lesion had approximately 25% higher on-treatment RLP cholesterol levels whereas the few patients with 2 new lesions had 100% higher RLP levels. We conclude that RLP, which is likely to reflect postprandially modifed VLDL, is strongly associated with both early and late signs of atherosclerosis.
71st EAS Congress and Satellite Symposia
7( C i
3.G. Nordestgaard, M.-L.M. Gronholdt, H. Laursen, H. Sillesen. Unicetwity 71Copenhagen. Denmark Fhis study tested the hypotheses that increased acute phase reactants predict :levated levels of triglyceride-rich lipoproteins, increased plaque volume as xell as echolucency of carotid plaques. The study included 258 patients xith >50°0 carotid artery stenosis. Acute phase reactants (orosomucoid, C•eacti~e protein, CRP) were measured in the fasting state, and lipoproteins ~efure and alter a standardized fatty meal. Echogenicity of carotid plaques xas evaluated using high-resolution B-mode ultrasound and computerlssisted image processing. A subgroup of 81 patients underwent carotid ;ndarterectomy. On linear regression analysis, orosomucoid levels were ~ositively associated with (I) lasting and postprandial levels of plasma riglyccrides, (2) intermediate densily lipoprotein triglycerides, (3) very low tensity lipoprotein/chylomicron remnant cholesterol and triglycerides, and 4) with the area under the plasma triglyceride curve 0 to 4 hours after a atty meal (all p-values < 0.0001 ); results for CRP were less pronounced. On nuhivariate analysis these results were confirmed. Orosomucoid and CRP )redicted the presence of an increased carotid plaque volume on univariate malysis (p = 0.01 and p = 0.02L however, only orosomucoid remained t predictor on multivariate analysis (p = 0.02). Finally, orosomucoid was ~egatively associated with echolucency of carotid plaques (p = 0.05). In :onclusion, increased acute phase reactants are associated with increased )lasma levels of triglyceride-rich lipoproteins. Furthermore, acute phase reactants predict an increased plaque volume and possibly plaque echolucency. ~IEMBRANE PROTEINS OF CHLAMYDIA PNEUMONIAE INDUCE ['HE S E C R E T I O N OF 92-kDa GELATINASE BY HUMAN ~IONOCYTE-DERIVED M A C R O P H A G E S
Vehmaan-Kreula t M. Puolakkainen 2, M. Sarvas 3, H.G. Welgus4, ~.T. Kovanen 1 . /Wihuri Research Institute. Kaltiolinnantie 4. Hetsinki; 'Department of Virology. Haartmaninkatu 3. Uniuersi~ o]" Helsinki." ~National Public Health Institute. Helsinki. Finland: 4Division of )ermatolog); Department of Medicine. Washington UnioersiO, School of ffedicine. St. Louis. USA dacrophages, mast cells and T-lymphocytes are the principal inflammatory :ell types of atherosclerotic lesions in human coronary atheromas. The nacrophages secrete matrix metalloproteinases (MMP's) which are capable )f degrading the extracellular matrix (ECM) components. In advanced ~therosclerotic lesions, sometimes can be found Chtamydia pneumoniae ~acteria. Here we have studied in vitro the ability of human monoeyte-derived nacrophages to secrete interstitial collagenase, stromelysin, 92-kDa gelatirose, and their inhibitor TIMP as a response to stimulation with Chlamytia pneumoniae. The metalloproteinase content of the monocyte-derived nacrophage supernatants was quantified by ELISA. We found that Chlamvfia pneumoniae induced the secretion of 92-kDa gelatinase but not of
87
interstitial collagenase, stromelysin or TIME We also found that induction of 92-kDa gelatinase production by C. pneumoniae acts throught its membrane proteins HSP 60, MOMP, and Omp 2, but not through its lipopolysaccharide component. The results show that C. pneumoniae induce secretion of an ECM-degrading enzyme, and so could contribute to the destabilization and rupture of atherosclerotic lesions.
C Y T O K I N E REGULATION OF VASCULAR NITRIC OXIDE SYNTHASES: IMPLICATIONS IN ATHEROSCLEROSIS
J.D. Catravas. Vascular Biolog), Center, Medical College of Georgia, Augusta. Georgia. USA The vessel wall is the locus of two isozymes of nitric oxide synthase (NOS): a largely constitutive type III (in endothelial cells) and a mostly inducible type I1 (in smooth muscle ceils). Small amounts of NO are tonically released by the constitutive type 111 NOS via a calcium-sensitive mechanism and are important contributors to the endothelial anti-inflammatory functions, including inhibition of endothelial - leukocyte interactions. Conversely, large amounts of NO are produced by type 11 NOS in response to various cytokines, via a calicum-independent mechanism and serve a proinflammatory function. Monocytes are early participants in the pathogenesis of atberosclerosis and a source of cytokines, including interleukin-I (IL-I). IL-I is not only a potent inducer of type It NOS, but also appears to downregulate type I11 NOS. Mechanisms of monocyte- and cytokine- mediated regulation of both NOS isozymes will be discussed.
-f Workshop: Triglyceride-rich lipoproteins and atherosclerosis REMNANTS OF POSTPRANDIAL T R I G L Y C E R I D E - R I C H LIPOPROTEINS AND ATHEROSCLEROSIS
E Karpe 1, S. Boquist 1, A. [,arsson l, A. Hamsten 1, A. Syv~nne2, M.-R. Taskinen2. /King Gustaf V Research Institute. Karolinska Hospital,
S-171 76 Stockholm. Sweden." 2Dept. of Medicine. UniuersiO, Hospital. 00029 Helsinki. Finland Recent studies suggest that VLDL metabolism is delayed and altered in the postprandial state. This is likely to lead to enhanced cholesteryl ester transfer protein-mediated exchange of cholesterol and triglycerides between HDL and VLDL. Recently, a novel method based on immunoaffinity separation of plasma for determination of remnant-like lipoproteins (RLP) has been developed. Interestingly, the compositional characteristics described for RLP are very similar to that of postprandially modified VLDL, i.e. cholesterol and apoE enrichment. It was therefore of interest to investigate the relationship between plasma levels of RLP cholesterol in both early and late stages of cardiovascular disease. First, a group of 91 healthy male 50-year old subjects homozygous for apoE3 was enrolled in a study of prognostic markers o f early atherosclerotic signs defined as an increased intima-media (IM) thickness analysed in the far wall of the carotid artery by B-mode ultrasound. Several parameters correlated significantly with carotid IM thickening, of those the strongest were: LDL r = 0.24, p < 0.05 and RLP r = 0.30, p < 0.01. All significant variables from a univariate statistical analysis were entered into a multiple stepwise regression analysis. RLP first entered the equation and explained 8% of the variability (r z = 0.08) the carotid IM thickness, independent of both LDL cholesterol plasma triglycerides. Second, RLP cholesterol levels were quantified in a 2-year double-blind, placebo-controlled angiographic study of gemfibrozil treatment including patients with low HDL cholesterol and a recent procedure of coronary artery bypass grafting, i.e. the Lopid Coronary Angiography Trial (LOCAT). Gemfibrozil treatment reduced RLP cholesterol by approximately 30%. The on-treatment level of RLP cholesterol was significantly associated with reduced progression of the minimum lumen diameter (p < 0.01 ) and a very signifcant effect was seen on the occurrence of new lesions in vein gratis. Subjects with 1 new lesion had approximately 25% higher on-treatment RLP cholesterol levels whereas the few patients with 2 new lesions had 100% higher RLP levels. We conclude that RLP, which is likely to reflect postprandially modifed VLDL, is strongly associated with both early and late signs of atherosclerosis.
71st EAS Congress and Satellite Symposia
7( C i