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Levonen AL, Patel RP, Brookes P, Go YM, Jo H, Parthasarathy S, Anderson PG, Darley-Usmar VM. Mechanisms of cell signaling by nitric oxide and peroxynitrite: from mitochondria to MAP kinases. Antioxid Redox Signal 2001; 3:215-29. [PMID: 11396477 DOI: 10.1089/152308601300185188] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Many of the biological and pathological effects of nitric oxide (NO) are mediated through cell signaling pathways that are initiated by NO reacting with metalloproteins. More recently, it has been recognized that the reaction of NO with free radicals such as superoxide and the lipid peroxyl radical also has the potential to modulate redox signaling. Although it is clear that NO can exert both cytotoxic and cytoprotective actions, the focus of this overview are those reactions that could lead to protection of the cell against oxidative stress in the vasculature. This will include the induction of antioxidant defenses such as glutathione, activation of mitogen-activated protein kinases in response to blood flow, and modulation of mitochondrial function and its impact on apoptosis. Models are presented that show the increased synthesis of glutathione in response to shear stress and inhibition of cytochrome c release from mitochondria. It appears that in the vasculature NO-dependent signaling pathways are of three types: (i) those involving NO itself, leading to modulation of mitochondrial respiration and soluble guanylate cyclase; (ii) those that involve S-nitrosation, including inhibition of caspases; and (iii) autocrine signaling that involves the intracellular formation of peroxynitrite and the activation of the mitogen-activated protein kinases. Taken together, NO plays a major role in the modulation of redox cell signaling through a number of distinct pathways in a cellular setting.
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Affiliation(s)
- A L Levonen
- Department of Pathology, University of Alabama at Birmingham, 35294-0019, USA
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52
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Okura T, Nakamura M, Takata Y, Watanabe S, Kitami Y, Hiwada K. Troglitazone induces apoptosis via the p53 and Gadd45 pathway in vascular smooth muscle cells. Eur J Pharmacol 2000; 407:227-35. [PMID: 11068018 DOI: 10.1016/s0014-2999(00)00758-5] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Thiazolidinediones, activators of peroxisome proliferator-activated receptor (PPAR)gamma, have been reported to induce apoptosis in many types of cells. In the present study, we investigated the effects of thiazolidinediones, troglitazone, and pioglitazone on the cell growth of vascular smooth muscle cells, and identified a specific effect of troglitazone in addition to PPARgamma activation. Subconfluent rat culture vascular smooth muscle cells were treated with or without PPARgamma activators, troglitazone (1-30 microM), or pioglitazone (1-30 microM) for 72 h. After treatment, cell viability was significantly reduced by troglitazone in concentrations of 5-30 microM but not by pioglitazone. Vascular smooth muscle cells appeared to float and shrink 48 h after treatment with 20 microM of troglitazone. In situ DNA labeling showed that the nuclei of these cells were positively stained, and genomic DNA extracted from the cells showed nucleosomal laddering. Messenger RNA expression levels of c-myc, p21, bax, bcl-2, and bcl-x were not changed by the treatment with troglitazone. In contrast, along with the induction of vascular smooth muscle cell apoptosis, both the mRNA and protein expression levels of p53 and Gadd45 markedly increased in response to troglitazone. These results strongly suggest that troglitazone can induce vascular smooth muscle cell apoptosis and that this effect is caused primarily by activation of the p53 and Gadd45 pathway but not by PPARgamma activation.
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MESH Headings
- Animals
- Apoptosis/drug effects
- Apoptosis/physiology
- Cell Survival/drug effects
- Cell Survival/physiology
- Cells, Cultured
- Chromans/pharmacology
- Gene Expression/drug effects
- Gene Expression/physiology
- Hypoglycemic Agents/pharmacology
- Intracellular Signaling Peptides and Proteins
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Pioglitazone
- Platelet Aggregation Inhibitors/pharmacology
- Proteins/drug effects
- Proteins/metabolism
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Cytoplasmic and Nuclear/drug effects
- Receptors, Cytoplasmic and Nuclear/physiology
- Thiazoles/pharmacology
- Thiazolidinediones
- Transcription Factors/drug effects
- Transcription Factors/physiology
- Troglitazone
- Tumor Suppressor Protein p53/drug effects
- Tumor Suppressor Protein p53/metabolism
- GADD45 Proteins
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Affiliation(s)
- T Okura
- The Second Department of Internal Medicine, Ehime University School of Medicine, Onsen-gun, Ehime 791-0295, Japan.
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53
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Abstract
Chronic pulmonary hypertension is a serious complication of a number of chronic lung and heart diseases. In addition to vasoconstriction, its pathogenesis includes injury to the peripheral pulmonary arteries leading to their structural remodeling. Increased pulmonary vascular synthesis of an endogenous vasodilator, nitric oxide (NO), opposes excessive increases of intravascular pressure during acute pulmonary vasoconstriction and chronic pulmonary hypertension, although evidence for reduced NO activity in pulmonary hypertension has also been presented. NO can modulate the degree of vascular injury and subsequent fibroproduction, which both underlie the development of chronic pulmonary hypertension. On one hand, NO can interrupt vascular wall injury by oxygen radicals produced in increased amounts in pulmonary hypertension. NO can also inhibit pulmonary vascular smooth muscle and fibroblast proliferative response to the injury. On the other hand, NO may combine with oxygen radicals to yield peroxynitrite and other related, highly reactive compounds. The oxidants formed in this manner may exert cytotoxic and collagenolytic effects and, therefore, promote the process of reparative vascular remodeling. The balance between the protective and adverse effects of NO is determined by the relative amounts of NO and reactive oxygen species. We speculate that this balance may be shifted toward more severe injury especially during exacerbations of chronic diseases associated with pulmonary hypertension. Targeting these adverse effects of NO-derived radicals on vascular structure represents a potential novel therapeutic approach to pulmonary hypertension in chronic lung diseases.
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Affiliation(s)
- V Hampl
- Department of Physiology, Charles University Second Medical School, Prague, Czech Republic
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54
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Durante W, Liao L, Reyna SV, Peyton KJ, Schafer AI. Physiological cyclic stretch directs L-arginine transport and metabolism to collagen synthesis in vascular smooth muscle. FASEB J 2000; 14:1775-83. [PMID: 10973927 DOI: 10.1096/fj.99-0960com] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Application of cyclic stretch (10% at 1 hertz) to vascular smooth muscle cells (SMC) increased L-arginine uptake and this was associated with a specific increase in cationic amino acid transporter-2 (CAT-2) mRNA. In addition, cyclic stretch stimulated L-arginine metabolism by inducing arginase I mRNA and arginase activity. In contrast, cyclic stretch inhibited the catabolism of L-arginine to nitric oxide (NO) by blocking inducible NO synthase expression. Exposure of SMC to cyclic stretch markedly increased the capacity of SMC to generate L-proline from L-arginine while inhibiting the formation of polyamines. The stretch-mediated increase in L-proline production was reversed by methyl-L-arginine, a competitive inhibitor of L-arginine transport, by hydroxy-L-arginine, an arginase inhibitor, or by the ornithine aminotransferase inhibitor L-canaline. Finally, cyclic stretch stimulated collagen synthesis and the accumulation of type I collagen, which was inhibited by L-canaline. These results demonstrate that cyclic stretch coordinately stimulates L-proline synthesis by regulating the genes that modulate the transport and metabolism of L-arginine. In addition, they show that stretch-stimulated collagen production is dependent on L-proline formation. The ability of hemodynamic forces to up-regulate L-arginine transport and direct its metabolism to L-proline may play an important role in stabilizing vascular lesions by promoting SMC collagen synthesis.
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Affiliation(s)
- W Durante
- Houston VA Medical Center and the Departments of Medicine. Pharmacology, Baylor College of Medicine, Houston, Texas 77030, USA.
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55
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Takahashi W, Suzuki JI, Izawa A, Takayama K, Yamazaki S, Isobe M. Inducible nitric oxide-mediated myocardial apoptosis contributes to graft failure during acute cardiac allograft rejection in mice. JAPANESE HEART JOURNAL 2000; 41:493-506. [PMID: 11041100 DOI: 10.1536/jhj.41.493] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The mechanism through which nitric oxide (NO) mediates cardiac myocyte death during acute cardiac rejection has not been fully delineated. We sought to determine whether NO promotes myocardial apoptosis and contributes to graft failure during acute cardiac rejection in a murine model. Heterotopic cardiac transplantation was performed from Balb/c (H-2d) to C3H/He mice (H-2k). Recipients were treated with aminoguanidine (AG) at 400 mg/kg every day after surgery. As references, we used isografts in Balb/c mice with and without AG treatment (400 mg/kg/day). Graft survival, histological changes and serum NO levels were assessed. Intra-graft apoptosis was evaluated using a DNA fragmentation detection assay (TUNEL method) and DNA laddering. Significant prolongation of graft survival was observed in allografts treated with AG in comparison with nontreated allografts. Serum NO levels, which peaked on day 7 in nontreated allografts, were significantly decreased in AG-treated allografts. AG treatment decreased the number of apoptotic cells and lowered the ratio of the apoptotic cardiac myocytes in contrast to that of the apoptotic infiltrating cells. DNA laddering was clearly detected in nontreated allografts but was suppressed in AG-treated allografts. Inhibition of NO production by AG prolonged murine cardiac allograft survival. The decrease in intra-graft apoptotic activity paralleled histological improvement. Cardiac myocyte death which occurs through an apoptotic process mediated by NO contributes to graft failure during acute cardiac rejection.
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Affiliation(s)
- W Takahashi
- Department of Internal Medicine, Shinshu University School of Medicine, Nagano, Japan
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56
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Mehta JL, Mehta P, Li D. Nitric oxide synthase in adult red blood cells: vestige of an earlier age or a biologically active enzyme? THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 2000; 135:430-1. [PMID: 10850640 DOI: 10.1067/mlc.2000.106802] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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57
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Zamora R, Vodovotz Y, Billiar TR. Inducible Nitric Oxide Synthase and Inflammatory Diseases. Mol Med 2000. [DOI: 10.1007/bf03401781] [Citation(s) in RCA: 158] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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58
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Sirsjö A, Gidlöf AC, Olsson A, Törmä H, Ares M, Kleinert H, Förstermann U, Hansson GK. Retinoic acid inhibits nitric oxide synthase-2 expression through the retinoic acid receptor-alpha. Biochem Biophys Res Commun 2000; 270:846-51. [PMID: 10772914 DOI: 10.1006/bbrc.2000.2535] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Retinoids are multipotent modulators of cellular functions and suppress cytokine-induced production of nitric oxide (NO) in several cell types. We have explored the mechanisms by which retinoic acid (RA) regulates NO production in rat aortic smooth muscle cells (VSMC), which express NOS2 in response to proinflammatory cytokines. RA inhibited interleukin-1beta (IL-1beta)-induced NOS2 mRNA expression and NO production. These effects were attenuated by the retinoic acid receptor (RAR) antagonist CD3106, indicating that they were mediated through retinoic acid receptors (RARs). The synthetic retinoid agonists CD336 (which specifically binds RARalpha) and CD367 (which binds all RARs) but not agonists specific for RARbeta, RARgamma, or RXRs reduced IL-1beta-induced NOS2 expression and NO production. When transfecting VSMC with a 1570-bp NOS2 promoter fragment fused to a luciferase reporter gene, the NOS2 promoter activity was inhibited by RA. These results indicate that retinoids modulate NO production in VSMC via RARalpha, which inhibits the transcription of the NOS2 gene.
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MESH Headings
- Animals
- Aorta, Thoracic/cytology
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Cells, Cultured
- Gene Expression Regulation, Enzymologic/drug effects
- Interleukin-1/pharmacology
- Kinetics
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Nitric Oxide Synthase/genetics
- Nitric Oxide Synthase Type II
- Promoter Regions, Genetic/drug effects
- Rats
- Rats, Sprague-Dawley
- Receptors, Retinoic Acid/drug effects
- Receptors, Retinoic Acid/physiology
- Retinoic Acid Receptor alpha
- Transcription, Genetic/drug effects
- Tretinoin/pharmacology
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Affiliation(s)
- A Sirsjö
- Center for Molecular Medicine, Karolinska Institute at the Karolinska Hospital, Stockholm, S-171 76, Sweden.
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59
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Kibbe MR, Nie S, Seol DW, Kovesdi I, Lizonova A, Makaroun M, Billiar TR, Tzeng E. Nitric oxide prevents p21 degradation with the ubiquitin-proteasome pathway in vascular smooth muscle cells. J Vasc Surg 2000; 31:364-74. [PMID: 10664504 DOI: 10.1016/s0741-5214(00)90166-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
PURPOSE We have shown that gene transfer of the inducible nitric oxide synthase (iNOS) gene to injured arteries inhibits the development of intimal hyperplasia. One mechanism by which nitric oxide (NO) may inhibit this process is through the upregulation of the cyclin-dependent kinase inhibitor p21, which induces a G0/G1 cell cycle arrest, leading to an inhibition of vascular smooth muscle cell (VSMC) proliferation. Because NO induced such a dramatic upregulation of p21 and because p21 is a universal inhibitor of the cell cycle, this study aimed to determine how NO upregulates p21 protein expression in VSMCs. METHODS p21 messenger RNA (mRNA) levels in rat aortic smooth muscle cells (RASMCs) were determined by Northern blot analysis after treatment with S-nitroso-N-acetylpenicillamine (SNAP) or after adenoviral iNOS gene transfer. p21 protein levels in RASMCs in similar conditions were determined by Western blot analysis. Levels of ubiquinated p21 in these same treatment groups were assessed by immunoprecipitation of p21 from RASMCs, followed by western blot analysis for ubiquitin. Protein tyrosine and protein serine/threonine phosphatase activity after treatment with SNAP, plus or minus the phosphatase inhibitors calyculin A or cantharidin, were measured with (32)P-labeled myelin basic protein as a substrate. RESULTS NO exposure by the NO-donor SNAP or iNOS gene transfer induced a dose- and time-dependent increase in p21 protein expression in RASMCs. p21 mRNA levels were significantly increased after SNAP treatment only at the 6-hour point, but were not increased at 24 hours. In contrast, protein levels were increased from 6 to 24 hours, and transcriptional inhibitors did not inhibit this increase in protein synthesis. The increase in p21 protein expression induced by NO was associated with less of the ubiquinated form of p21 at both early and late points. Furthermore, NO induced an increase in both protein tyrosine and protein serine/threonine phosphatase activity. Inhibition of these phosphatases with calyculin A or cantharidin prevented the upregulation of p21 protein expression by NO. CONCLUSION These data indicate that one mechanism by which NO upregulates p21 protein expression is through the prevention of p21 protein degradation by the ubiquitin-proteasome pathway in association with increased protein tyrosine and serine/threonine phosphatase activity.
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MESH Headings
- Adenosine Triphosphatases/drug effects
- Adenosine Triphosphatases/metabolism
- Animals
- Aorta, Thoracic/cytology
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Cells, Cultured
- Cyclin-Dependent Kinase Inhibitor p21
- Cyclins/drug effects
- Cyclins/metabolism
- Cysteine Endopeptidases/drug effects
- Cysteine Endopeptidases/metabolism
- Enzyme Inhibitors/metabolism
- Multienzyme Complexes/drug effects
- Multienzyme Complexes/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Nitric Oxide/pharmacology
- Nitric Oxide Synthase/genetics
- Nitric Oxide Synthase Type II
- Proteasome Endopeptidase Complex
- Rats
- Rats, Sprague-Dawley
- Time Factors
- Transduction, Genetic
- Ubiquitins/drug effects
- Ubiquitins/metabolism
- Up-Regulation/drug effects
- Vasodilator Agents/pharmacology
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Affiliation(s)
- M R Kibbe
- Department of Surgery, University of Pittsburgh, and GenVec Corporation, Pittsburgh, PA 15261, USA
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60
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Saito S, Aras RS, Lou H, Ramwell PW, Foegh ML. Effects of estrogen on nitric oxide synthase expression in rat aorta allograft and smooth muscle cells. J Heart Lung Transplant 1999; 18:937-45. [PMID: 10561103 DOI: 10.1016/s1053-2498(99)00060-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND We find that chronic estradiol treatment inhibits the development of transplant arteriosclerosis (TA). The mechanism of this inhibition remains unclear. The objective of this study is to investigate in a non-cyclosporin-requiring TA model whether estradiol-17beta treatment modulates the expression of both endothelial nitric oxide synthase (ecNOS) and inducible nitric oxide synthase (iNOS) in the early phase following transplantation. METHODS Orthotopic abdominal aorta allograft transplantation was performed in male rats using Brown-Norway rats as donors and Lewis rats as recipients. The recipients (n = 50) were treated with estradiol 20 microg/kg/day or placebo by osmotic minipump from 2 days prior to surgery until sacrifice on post-operative days 1, 3, 7, 14, and 21. The allografts were harvested and cross-sections of the vascular tissues were used for immunohistochemical staining of ecNOS and iNOS. The effects of estradiol on cytokine-induced (tumor necrosis factor-alpha and interleukin-1 beta iNOS protein and messenger RNA (mRNA) expression were also evaluated on rat aorta smooth muscle cells by Western blotting and RT-PCR in vitro, respectively. RESULTS The expression of ecNOS and iNOS was graded semiquantitatively from 0 to +3. Estrogen elevates ecNOS expression in the intima in the early phase following transplantation, 0.85 +/- 0.14 (day 7) and 1.08 +/- 0.11 (day 14) vs 1.53 +/- 0.25 (day 7) and 1.60 +/- 0.17 (day 14) for placebo and estradiol treated groups respectively, p < 0.01. Estrogen suppresses iNOS expression in neointima (0.67 +/- 0.17 vs 0.24 +/- 0.04, p < 0.01, day 14), media (1.03 +/- 0.15 vs 0.4 +/- 0.09, p < 0.01, day 7), and adventitia (1.55 +/- 0.12 vs 1.02 +/- 0.10, p < 0.05, day 14) in the same phase. Estradiol treatment inhibits cytokine-induced iNOS mRNA expression in cultured smooth muscle cells. CONCLUSIONS Chronic estrogen treatment modulates both ecNOS and iNOS expression in the early phase following transplantation. This is associated with the estrogen-protective effects on TA.
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MESH Headings
- Animals
- Aorta, Abdominal/cytology
- Aorta, Abdominal/drug effects
- Aorta, Abdominal/enzymology
- Aorta, Abdominal/transplantation
- Arteriosclerosis/chemically induced
- Arteriosclerosis/enzymology
- Cells, Cultured
- Disease Models, Animal
- Estradiol/pharmacology
- Immunohistochemistry
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Nitric Oxide Synthase/drug effects
- Nitric Oxide Synthase Type II
- Nitric Oxide Synthase Type III
- Random Allocation
- Rats
- Rats, Inbred Lew
- Time Factors
- Transplantation, Homologous
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Affiliation(s)
- S Saito
- Department of Surgery, Georgetown University Medical Center, Washington, DC 20007, USA
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61
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Pinsky DJ, Aji W, Szabolcs M, Athan ES, Liu Y, Yang YM, Kline RP, Olson KE, Cannon PJ. Nitric oxide triggers programmed cell death (apoptosis) of adult rat ventricular myocytes in culture. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:H1189-99. [PMID: 10484441 DOI: 10.1152/ajpheart.1999.277.3.h1189] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Excessive nitric oxide (NO) production within the heart is implicated in the pathogenesis of myocyte death, but the mechanism whereby NO kills cardiac myocytes is not known. To determine whether NO may trigger programmed cell death (apoptosis) of adult rat ventricular myocytes in culture, the NO donor S-nitroso-N-acetylpenicillamine (SNAP) was shown to kill purified cardiac myocytes in a dose-dependent fashion. In situ analysis of ventricular myocytes plated on chamber slides using nick-end labeling of DNA demonstrated that SNAP induces cardiac myocyte apoptosis, which was confirmed by the identification of oligonucleosomal DNA fragmentation on agarose gel electrophoresis. Similarly, treatment of cardiac myocytes with cytokines that induce inducible NO synthase was shown to cause an NO-dependent induction of apoptosis. Addition of reduced hemoglobin to scavenge NO liberated by SNAP extinguished both the increase in percentage of apoptotic cells and the appearance of DNA ladders. Treatment with SNAP (but not with N-acetylpenicillamine or SNAP + hemoglobin) not only induced apoptosis but resulted in a marked increase in p53 expression in cardiac myocytes detected by Western blotting and immunohistochemistry. These data indicate that NO has the capacity to kill cardiac myocytes by triggering apoptosis and suggest the involvement of p53 in this process.
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Affiliation(s)
- D J Pinsky
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
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62
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Behbahani R, Verme-Gibboney C, Romanelli AM. Chlamydia pneumoniae and anti-infective therapy: their role in the pathogenesis and treatment of coronary artery disease. Clin Ther 1999; 21:1286-300; discussion 1285. [PMID: 10485501 DOI: 10.1016/s0149-2918(99)80030-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cardiovascular disease remains the most common cause of death in the United States; however, conventional cardiovascular risk factors fail to explain completely the pathogenesis of atherosclerosis and coronary artery disease. There has been recent interest in the association between Chlamydia pneumoniae and the risk of development or progression of atherosclerotic disease. This association has become evident through serologic, pathologic, and animal-based models and, more recently, through limited trials of antichlamydial antibiotics in humans. Whether C. pneumoniae is a causative agent or "innocent bystander" or whether antibiotic therapy has any role in the treatment of cardiovascular disease remains to be determined.
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Affiliation(s)
- R Behbahani
- Product Information Department, SmithKline Beecham Pharmaceuticals, Philadelphia, Pennsylvania 19101, USA
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63
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Weber KT. Angiotensin II and connective tissue: homeostasis and reciprocal regulation. REGULATORY PEPTIDES 1999; 82:1-17. [PMID: 10458642 DOI: 10.1016/s0167-0115(99)00032-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
As a concept traditionally applied to integrative organ physiology, homeostasis likewise applies to self-regulated growth and structure of loose, dense and specialized connective tissues. De novo generation and co-induction of signals, either stimulatory or inhibitory to the formation of these tissues, provide for a reciprocal regulation of their composition; angiotensin (Ang) II is a growth stimulator. Components involved in AngII generation and its biological activity, including angiotensin converting enzyme (ACE) and AngII receptors, are expressed by mesenchymal cells responsible for connective tissue turnover. ACE inhibition or AT1 receptor antagonism attenuate the formation of these connective tissues. The concept of circulatory homeostasis, and the endocrine properties of plasma AngII involved in maintaining same, need each be broadened to encompass auto- and paracrine effects of AngII produced within connective tissues, where it contributes to their homeostatic regulation of structure and composition.
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Affiliation(s)
- K T Weber
- Division of Cardiology, University of Missouri Health Sciences Center, Columbia, USA.
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64
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Hansen PR, Holm AM, Andersen CB, Haunsø S. Aminoguanidine induces constrictive vascular remodeling and inhibits smooth muscle cell death after balloon injury. Eur J Pharmacol 1999; 372:157-66. [PMID: 10395095 DOI: 10.1016/s0014-2999(99)00173-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We examined the effects of aminoguanidine, an inhibitor of inducible nitric oxide synthase, in the rat model of balloon injury. Arteries were assessed by histomorphometry, and vascular smooth muscle cell death and proliferation were examined 24 h and 14 days after balloon injury by in situ terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) of fragmented DNA and expression of proliferating cell nuclear antigen, respectively. Aminoguanidine decreased the luminal area 14 days after balloon injury (0.19+/-0.04 mm2 vs. 0.35+/-0.02 mmr2; P < 0.005), and this effect was attributable to reduction of the total vessel area, i.e., constrictive vascular remodeling (0.42+/-0.03 mm2 vs. 0.55+/-0.03 mm2; P < 0.005). At 24 h after injury, the percentage of TUNEL-positive cells in the medial layer was reduced by aminoguanidine (2.0+/-1.0% vs. 17.3+/-5.4%; P < 0.05), and the percentage of proliferating cells was increased (18.4+/-5.5% vs. 4.9+/-2.2%; P < 0.05). Aminoguanidine did not influence the density of VSMC nuclei in the injured artery wall, systemic blood pressure or endothelium-dependent vasorelaxation. We conclude, that in the rat model of balloon injury, aminoguanidine induces luminal loss by constrictive vascular remodeling in association with reduced early VSMC death and increased proliferation.
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Affiliation(s)
- P R Hansen
- Department of Cardiology P, Gentofte University Hospital, Hellerup, Denmark.
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65
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Katsuyama K, Shichiri M, Kato H, Imai T, Marumo F, Hirata Y. Differential inhibitory actions by glucocorticoid and aspirin on cytokine-induced nitric oxide production in vascular smooth muscle cells. Endocrinology 1999; 140:2183-90. [PMID: 10218970 DOI: 10.1210/endo.140.5.6718] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Glucocorticoids and nonsteroidal antiinflammatory drugs (NSAIDs) are widely used for the treatment of inflammatory and immune diseases. Nitric oxide (NO) has a diversity of physiological functions, but its excess production has been implicated in the inflammatory process. The present study was designed to elucidate the mechanisms by which glucocorticoids and NSAIDs affect inducible nitric oxide synthase (iNOS) expression in cultured rat vascular smooth muscle cells (VSMCs). Both interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha potently stimulated nitrite/nitrate (NOx) production with a concomitant expression of iNOS mRNA and protein as demonstrated by Northern and Western blot analysis, respectively. Both IL-1beta and TNF-alpha activated nuclear factor (NF)-kappaB as demonstrated by electrophoretic mobility shift assay. Dexamethasone, salicylate and aspirin, but not indomethacin, dose dependently inhibited cytokine-stimulated NOx production and iNOS protein expression. Dexamethasone decreased cytokine-induced NF-kappaB activation and iNOS mRNA expression, but neither salicylate nor aspirin affected NF-kappaB activation or iNOS mRNA expression. IL-1beta caused a rapid increase in phosphorylated IkappaB-alpha levels and subsequent transient decrease in IkappaB-alpha levels, an inhibitor of NF-kappaB, as revealed by Western blot analysis using specific antibodies for phosphorylated and nonphosphorylated IkappaB-alpha. These effects were blocked by pretreatment with dexamethasone. Aspirin dose dependently inhibited iNOS enzymatic activity, whereas salicylate and dexamethasone had limited effect. The present study demonstrates that 1) inhibitory effect of dexamethasone on cytokine-induced iNOS expression and NO production in rat VSMCs, although potentially acting at multiple levels, is partly mediated by inhibition of NF-kappaB activation resulting from decreased phosphorylation and degradation of IkappaB-alpha, 2) both salicylate and aspirin inhibit cytokine-stimulated NO production at translational and/or posttranslational levels without affecting NF-kappaB- mediated iNOS gene expression, and 3) aspirin directly inhibits iNOS enzyme activity. These data suggest the differential inhibitory mechanisms of iNOS-mediated NO synthesis by glucocorticoids and NSAIDs in the vasculature.
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Affiliation(s)
- K Katsuyama
- Second Department of Internal Medicine, Tokyo Medical and Dental University, Japan
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