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D D Heistad

Publications and source records attributed to D D Heistad.

At least 37 records · Page 2Linked to original sources
PubMed2000

Gene therapy of hypertensive vascular injury.

Hypertension and vascular injury usually require prolonged treatment, and compliance is a key to efficacy for pharmacologically-based antihypertensive therapy. Gene therapy has the potential to be long lasting, with few side effects. Recent studies have provided promising results, in which hypertension can be treated by either augmentation of vasodilation or inhibition of vasoconstriction through gene transfer in experimental models. Gene transfer is also becoming useful for the study of mechanisms of physiologic and pathophysiologic conditions, including hypertension. In this mini-review, we summarize some recent studies in this area of research, and suggest some areas where progress is needed to advance the research toward gene therapy.

Gene Transfer Techniques↗
PubMed2000

Calcium phosphate precipitates augment adenovirus-mediated gene transfer to blood vessels in vitro and in vivo.

Adenovirus (Ad)-mediated gene transfer to blood vessels is relatively inefficient, probably because binding of adenovirus to the endothelium and adventitia seems to be limited. Association of calcium phosphate (CaPi) precipitates with adenovirus improves efficiency of gene transfer to some cells in culture and to mouse lung in vivo. In this study, we tested the hypothesis that CaPi is useful for adenovirus-mediated gene transfer to blood vessels. In fibroblast and endothelial cells in culture, Ad:CaPi coprecipitates greatly increased transgene expression. Ad:CaPi also enhanced transgene expression in both adventitia and endothelium of carotid arteries and aortae from rabbits studied ex vivo. After injection of Ad:CaPi into the cisterna magna of rabbits in vivo, the transgene product was markedly increased in leptomeninges of the ventral brain stem, including the adventitia of the basilar artery. We also examined mechanisms of enhanced gene transfer. Binding of adenovirus to fibroblast and endothelial cells in culture, and to the basilar artery in vivo, as determined using Southern blot analysis, was augmented by CaPi. Antibody to adenoviral fiber knob did not inhibit augmented transgene expression by Ad:CaPi. The finding suggests that improved adenoviral binding occurs primarily via a fiber-independent pathway. Thus, CaPi precipitates are useful for improvement of adenovirus-mediated gene transfer to blood vessels in vitro and in vivo.

3T3 Cells↗
PubMed2000

Gene transfer of calcitonin gene-related peptide to cerebral arteries.

Overexpression of calcitonin gene-related peptide (CGRP), an extremely potent vasodilator, to blood vessels is a possible strategy for prevention of vasospasm. We constructed an adenoviral vector that encodes prepro-CGRP (Adprepro-CGRP) and examined the effects of gene transfer on cultured cells and cerebral arteries. Transfection of Adprepro-CGRP to Cos-7 and NIH-3T3 cells increased CGRP-like immunoreactivity in media and produced an increase in cAMP in recipient cells. Five days after injection of Adprepro-CGRP into the cisterna magna of rabbits, the concentration of CGRP-like immunoreactivity increased by 93-fold in cerebrospinal fluid. In basilar artery, cAMP increased by 2.3-fold after Adprepro-CGRP compared with a control adenovirus. After transfection of Adprepro-CGRP, contraction of basilar artery in vitro to histamine and serotonin was attenuated, and relaxation to an inhibitor of cyclic nucleotide phosphodiesterase 3-isobutyl-1-methylxanthine was augmented compared with nontransduced arteries or arteries transfected with a control gene. Altered vascular responses were restored to normal by pretreatment with a CGRP(1) receptor antagonist CGRP-(8-37). Thus gene transfer of prepro-CGRP in vivo overexpresses CGRP in cerebrospinal fluid and perivascular tissues and modulates vascular tone. We speculate that this approach may be useful in prevention of vasospasm after subarachnoid hemorrhage.

1-Methyl-3-isobutylxanthine↗
PubMed2000

Potassium channels modulate cerebral autoregulation during acute hypertension.

We tested the hypothesis that constriction of cerebral arterioles during acute increases in blood pressure is attenuated by activation of potassium (K(+)) channels. We tested the effects of inhibitors of calcium-dependent K(+) channels [iberiotoxin (50 nM) and tetraethylammonium (TEA, 1 mM)] on changes in arteriolar diameter during acute hypertension. Diameter of cerebral arterioles (baseline diameter = 46 +/- 2 microm, mean +/- SE) was measured using a cranial window in anesthetized rats. Arterial pressure was increased from a control value of 96 +/- 1 mmHg to 130, 150, 170, and 200 mmHg by intravenous infusion of phenylephrine. Increases in arterial pressure from baseline to 130 and 150 mmHg decreased the diameter of cerebral arterioles by 5-10%. Greater increases in arterial pressure produced large increases in arteriolar diameter (i.e., "breakthrough of autoregulation"). Iberiotoxin or TEA inhibited increases in arteriolar diameter when arterial pressure was increased to 170 and 200 mmHg. The change in arteriolar diameter at 200 mmHg was 20 +/- 3% and -1 +/- 4% in the absence and presence of iberiotoxin, respectively. These findings suggest that calcium-dependent K(+) channels attenuate cerebral microvascular constriction during acute increases in arterial pressure, and that increases in arteriolar diameter at high levels of arterial pressure are not simply a passive phenomenon.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2000

Folate dependence of hyperhomocysteinemia and vascular dysfunction in cystathionine beta-synthase-deficient mice.

Hyperhomocysteinemia is a risk factor for stroke, myocardial infarction, and venous thrombosis. Moderate hyperhomocysteinemia is associated with impaired endothelial function, but the mechanisms responsible for endothelial dysfunction in hyperhomocysteinemia are poorly understood. We have used genetic and dietary approaches to produce hyperhomocysteinemia in mice. Heterozygous cystathionine beta-synthase-deficient mice (CBS +/-), which have a selective defect in homocysteine transsulfuration, and wild-type (CBS +/+) littermates were fed either a control diet or a diet that is relatively deficient in folic acid for 6 wk. Plasma total homocysteine was 5.3 +/- 0.7 microM in CBS +/+ mice and 6.4 +/- 0.6 microM in CBS +/- mice (P = 0.3) given the control diet. Plasma total homocysteine was 11.6 +/- 4.5 microM in CBS +/+ mice and 25.1 +/- 3.2 microM in CBS +/- mice (P = 0.004) given a low-folate diet. In mice fed the control diet, relaxation of aortic rings in response to the endothelium-dependent vasodilator acetylcholine did not differ significantly between CBS +/+ mice and CBS +/- mice. In contrast, in mice fed a low-folate diet, maximal relaxation to acetylcholine was markedly impaired in CBS +/- mice (58 +/- 9%) compared with CBS +/+ mice (84 +/- 4%) (P = 0.01). No differences in relaxation to the endothelium-independent vasodilator sodium nitroprusside were observed among the four groups of mice. These data indicate that CBS-deficient mice are predisposed to hyperhomocysteinemia during dietary folate deficiency, and moderate hyperhomocysteinemia is associated with marked impairment of endothelial function in mice.

Animals↗
PubMed2000

IL-10 deficiency increases superoxide and endothelial dysfunction during inflammation.

Little is known about the role of interleukin-10 (IL-10), an anti-inflammatory cytokine, in blood vessels. We used IL-10-deficient mice (IL-10 -/-) to examine the hypothesis that IL-10 protects endothelial function after lipopolysaccharide (LPS) treatment. The responses of carotid arteries were studied in vitro 6 h after injection of a relatively low dose of LPS (10 microgram ip). In IL-10 -/- mice, the maximum relaxation to ACh (3 microM) was 56 +/- 6% (means +/- SE) after LPS injection and 84 +/- 4% after vehicle injection (P < 0.05). Thus endothelium-dependent relaxation was impaired in carotid arteries from IL-10 -/- mice after LPS injection. In contrast, this dose of LPS did not alter relaxation to ACh in vessels from wild-type (IL-10 +/+) mice. Relaxation to nitroprusside and papaverine was similar in arteries from both IL-10 -/- and IL-10 +/+ mice after vehicle or LPS injection. Because inflammation is associated with increased levels of reactive oxygen species, we also tested the hypothesis that superoxide contributes to the impairment of endothelial function by LPS in the absence of IL-10. Results using confocal microscopy and hydroethidine indicated that levels of superoxide are elevated in carotid arteries from IL-10 -/- mice compared with IL-10 +/+ mice after LPS injection. The impaired relaxation of arteries from IL-10 -/- mice after LPS injection was restored to normal by polyethylene glycol-suspended superoxide dismutase (50 U/ml) or allopurinol (1 mM), an inhibitor of xanthine oxidase. These data provide direct evidence that IL-10 protects endothelial function after an acute inflammatory stimulus by limiting local increases in superoxide. The source of superoxide in this model may be xanthine oxidase.

Animals↗
PubMed2000

Tumor necrosis factor-alpha impairs contraction but not relaxation in carotid arteries from iNOS-deficient mice.

We used mice deficient in expression of inducible NO synthase (iNOS -/-) to directly examine the role of iNOS in impaired vasoconstrictor responses following tumor necrosis factor-alpha (TNF-alpha). In iNOS +/+ mice, contraction of carotid arteries in response to prostaglandin F(2alpha) (PGF(2alpha)) was impaired following TNF-alpha (100 microg/kg ip)(n = 10, P < 0.01). In contrast to responses in wild-type mice, contraction to low concentrations of PGF(2alpha) were normal, but maximum contraction to PGF(2alpha) was impaired in arteries from iNOS -/- mice treated with TNF-alpha [0.35 +/-.0.02 g (n = 8) following vehicle and 0.25 +/- 0.02 g (n = 7) following TNF-alpha (P < 0.05)]. Aminoguanidine, a relatively selective inhibitor of iNOS, partially restored contraction to PGF(2alpha) in vessels from iNOS +/+ mice but had no effect in iNOS -/- mice injected with TNF-alpha, suggesting that a mechanism(s) other than iNOS contributes to impaired responses. In contrast to contractile responses, relaxation of the carotid artery in response to acetylcholine and nitroprusside was not altered following TNF-alpha in iNOS +/+ or iNOS -/-mice. Responses of carotid arteries from iNOS -/- mice and effects of aminoguanidine suggest that both iNOS-dependent and iNOS-independent mechanisms contribute to impaired contractile responses following TNF-alpha.

Acetylcholine↗
PubMed2000

Plasma concentration of asymmetric dimethylarginine, an endogenous inhibitor of nitric oxide synthase, is elevated in monkeys with hyperhomocyst(e)inemia or hypercholesterolemia.

Hyperhomocyst(e)inemia is associated with endothelial dysfunction. Mechanisms responsible for endothelial dysfunction in hyperhomocyst(e)inemia may involve impaired bioavailability of endothelium-dependent nitric oxide. We tested the hypothesis that hyperhomocyst(e)inemia is associated with an elevated plasma concentration of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase. One group of adult cynomolgus monkeys was fed either a control or hyperhomocyst(e)inemic diet for 4 weeks in a randomized crossover design. The second group was fed an atherogenic diet that produces both hyperhomocyst(e)inemia and hypercholesterolemia for 17 months, followed by an atherogenic diet supplemented with B vitamins for 6 months to decrease plasma homocyst(e)ine concentration. Human endothelial cells were used to study the effects of methionine and homocysteine in the presence or absence of B vitamins or the methylation inhibitor S-adenosylhomocysteine on the formation of ADMA and its inactive stereoisomer, symmetric dimethylarginine. The hyperhomocyst(e)inemic diet produced 2- to 3-fold increases in plasma levels of homocyst(e)ine and ADMA (both P<0.05). The atherogenic diet also produced elevated plasma levels of homocyst(e)ine and ADMA (both P<0. 05). Supplementation of the atherogenic diet with B vitamins decreased the plasma levels of homocyst(e)ine but did not affect the plasma levels of ADMA or endothelial function. There was a strong correlation between plasma ADMA and homocyst(e)ine and a strong inverse correlation between ADMA and carotid artery relaxation to acetylcholine. ADMA release by cultured endothelial cells was significantly increased in the presence of methionine or homocysteine. This effect was blocked by S-adenosylhomocysteine but not by B vitamins. We conclude that plasma levels of ADMA are elevated in hyperhomocyst(e)inemia. Because ADMA acts as a competitive inhibitor of endothelial nitric oxide synthase, these findings suggest a novel mechanism for impaired endothelial function in hyperhomocyst(e)inemia.

Animals↗
PubMed2000

Gene transfer of endothelial nitric oxide synthase reduces angiotensin II-induced endothelial dysfunction.

Angiotensin II stimulates vascular NADPH oxidase to produce superoxide, which can react with nitric oxide and impair vasomotor function. We tested the hypothesis that the overexpression of endothelial nitric oxide synthase (eNOS) or superoxide dismutase (SOD) would correct angiotensin II-induced endothelial dysfunction. We examined the effects of the gene transfer of eNOS or 2 isoforms of SOD to the aorta in angiotensin II-treated rabbits on vasomotor function. New Zealand White rabbits were treated for 1 week with angiotensin II (100 ng. kg(-1). min(-1)) or saline by osmotic minipumps. In angiotensin II-treated rabbits, mean blood pressure was 107+/-8 mm Hg; it was 67+/-5 mm Hg in saline-infused rabbits (P<0.05). In aortas from angiotensin II-treated rabbits, lucigenin-enhanced chemiluminescence demonstrated a 2.5-fold increase in superoxide levels, and the oxidative fluorescent probe hydroethidine indicated increased superoxide levels throughout the vascular wall, especially in the endothelium and adventitia. Maximal relaxation to acetylcholine was less in aortas from rabbits treated with angiotensin II (72+/-5% versus 87+/-4% in saline-treated rabbits; P<0.01), but responses to sodium nitroprusside were similar. Segments of the thoracic aorta were incubated in vitro with an adenoviral vector that expressed eNOS, copper zinc SOD (CuZnSOD), extracellular SOD (ECSOD), or beta-galactosidase. beta-Gal treatment with adenovirus containing the gene for eNOS (AdeNOS) but not adenovirus containing the gene for beta-gal (Adbeta-gal) (control virus) restored responses to acetylcholine (82+/-3% after AdeNOS and 67+/-4% after Adbeta-gal). Gene transfer of CuZnSOD or ECSOD did not improve the endothelium-dependent relaxation of the aorta in rabbits that received angiotensin II. Thus, gene transfer of eNOS, but not SOD, effectively restores vasomotor function in angiotensin II-infused rabbits.

Angiotensin II↗
PubMed1999

Gene transfer of endothelial nitric oxide synthase to the lung of the mouse in vivo. Effect on agonist-induced and flow-mediated vascular responses.

The effects of transfer of the endothelial nitric oxide synthase (eNOS) gene to the lung were studied in mice. After intratracheal administration of AdCMVbetagal, expression of the beta-galactosidase reporter gene was detected in pulmonary airway cells, in alveolar cells, and in small pulmonary arteries. Gene expression with AdCMVbetagal peaked 1 day after administration and decayed over a 7- to 14-day period, whereas gene expression after AdRSVbetagal transfection peaked on day 5 and was sustained over a 21- to 28-day period. One day after administration of AdCMVeNOS, eNOS protein levels were increased, and there was a small reduction in mean pulmonary arterial pressure and pulmonary vascular resistance. The pressure-flow relationship in the pulmonary vascular bed was shifted to the right in animals transfected with eNOS, and pulmonary vasodepressor responses to bradykinin and the type V cGMP-selective phosphodiesterase inhibitor zaprinast were enhanced, whereas systemic responses were not altered. Pulmonary vasopressor responses to endothelin-1 (ET-1), angiotensin II, and ventilatory hypoxia were reduced significantly in animals transfected with the eNOS gene, whereas pressor responses to norepinephrine and U46619 were not changed. Systemic pressor responses to ET-1 and angiotensin II were similar in eNOS-transfected mice and in control mice. Intratracheal administration of AdRSVeNOS attenuated the increase in pulmonary arterial pressure in mice exposed to the fibrogenic anticancer agent bleomycin. These data suggest that transfer of the eNOS gene in vivo can selectively reduce pulmonary vascular resistance and pulmonary pressor responses to ET-1, angiotensin II, and hypoxia; enhance pulmonary depressor responses; and attenuate pulmonary hypertension induced by bleomycin. Moreover, these data suggest that in vivo gene transfer may be a useful therapeutic intervention for the treatment of pulmonary hypertensive disorders.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1999

Gene transfer of endothelial nitric oxide synthase (eNOS) in eNOS-deficient mice.

Relaxation to acetylcholine (ACh) and calcium ionophore (A-23187) is absent in aortas from endothelial nitric oxide synthase (eNOS)-deficient (eNOS -/-) mice. We hypothesized that gene transfer of eNOS would restore relaxation to ACh and A-23187 in eNOS -/- mice. Aortic rings from eNOS -/- and eNOS +/+ mice were exposed in vitro to vehicle or adenoviral vectors encoding beta-galactosidase (lacZ) or eNOS. Histochemical staining for beta-galactosidase and eNOS demonstrated transduction of endothelial cells and adventitia. Vehicle-treated vessels from eNOS -/- mice did not relax to ACh or A-23187 compared with eNOS +/+ mice. In contrast, relaxation to nitroprusside (NP) was significantly greater in eNOS -/- mice than in eNOS +/+ mice. Gene transfer of eNOS, but not lacZ, to vascular rings of eNOS -/- mice restored relaxation to ACh and A-23187. In vessels from eNOS -/- mice that were transduced with eNOS, N(omega)-nitro-L-arginine (10(-4) M) inhibited relaxation to ACh and A-23187 but not NP. Thus vascular function can be significantly improved by gene transfer in vessels where a major relaxation mechanism is genetically absent.

Adenoviridae↗
PubMed1999

Impaired anticoagulant response to infusion of thrombin in atherosclerotic monkeys associated with acquired defects in the protein C system.

To examine the effects of atherosclerosis on the protein C anticoagulant pathway in vivo, we measured anticoagulant responses to intravenous administration of human alpha-thrombin or activated protein C (APC) in cynomolgus monkeys. Two groups of monkeys were fed either a control diet (n=18) or an atherogenic diet (n=12) that produces both hypercholesterolemia and moderate hyperhomocyst(e)inemia. A third group (n=8) was fed an atherogenic diet for 15 months, and then fed the atherogenic diet supplemented with B vitamins for 6 months to correct the hyperhomocyst(e)inemia. The plasma homocyst(e)ine level was higher in monkeys fed the atherogenic diet (9.6+/-1.0 micromol/L) than in monkeys fed the control diet (3.7+/-0.2 micromol/L) or the atherogenic diet with B vitamins (3.6+/-0.2 micromol/L) (P<0.001). Infusion of thrombin produced a much greater prolongation of the activated partial thromboplastin time in monkeys fed the control diet (52+/-10 seconds) than in monkeys fed the atherogenic diet either with (24+/-4 seconds) or without (27+/-5 seconds) supplemental B vitamins (P<0.02). Thrombin-dependent generation of circulating APC was higher in control (294+/-17 U/mL) than in atherosclerotic (240+/-14 U/mL) monkeys (P<0.05), although levels of fibrinogen, plasminogen, D-dimer, and thrombin-antithrombin complexes were similar in each group. Injection of human APC produced a similar prolongation of the activated partial thromboplastin time in control (31+/-3 seconds) and atherosclerotic (29+/-2 seconds) monkeys. These findings provide evidence for impaired anticoagulation, due partly to decreased formation of APC, in atherosclerosis. The blunted anticoagulant response to thrombin in hypercholesterolemic monkeys was not corrected by supplementation with B vitamins.

Animals↗
PubMed1999

Adenovirus-mediated gene transfer is augmented in basilar and carotid arteries of heritable hyperlipidemic rabbits.

BACKGROUND AND PURPOSE: There are major differences in susceptibility of intracranial and extracranial arteries to atherosclerosis. The goal of this study was to examine adenovirus-mediated gene transfer to basilar and carotid arteries of Watanabe heritable hyperlipidemic (WHHL) rabbits, which have spontaneous hypercholesterolemia and atherosclerosis, and normal New Zealand White (NZW) rabbits. We used 2 different adenoviral vectors, driven by either cytomegalovirus (CMV) or Rous sarcoma virus (RSV) promoters. METHODS: Basilar and carotid arteries were removed from WHHL and NZW rabbits and cut into rings. The arteries were incubated with an adenoviral vector that expresses beta-galactosidase and is driven by either a cytomegalovirus (CMV) or Rous sarcoma virus (RSV) promoter (AdCMVbetagal or AdRSVbetagal). Arteries were incubated with virus for 2 hours, and then incubated in medium for 24 hours to allow expression of transgene. Transgene expression was assessed by enzyme activity (Galacto-Light assay) and by a histochemical method after X-Gal staining. RESULTS: After gene transfer, beta-galactosidase was expressed in endothelium and adventitia but not media. There were moderately severe atherosclerotic lesions in carotid arteries and early lesions in basilar arteries. Enzyme activity after gene transfer with AdCMVbetagal (3x10(11) particles/mL) was greater in the basilar artery of WHHL than NZW (137+/-40 versus 25+/-10 mU/mg protein, P<0.05) (mean+/-SE) and in the carotid artery (133+/-27 versus 34+/-11 mU/mg protein, P<0.05). After gene transfer with AdRSVbetagal, transgene expression was similar in arteries from WHHL and normal NZW rabbits. CONCLUSIONS: This is the first study to examine gene transfer to intracranial and extracranial arteries from atherosclerotic animals. The findings suggest that an adenoviral vector with a CMV, but not RSV, promoter provides greater transgene expression in the basilar and carotid arteries from spontaneously atherosclerotic rabbits than from normal rabbits.

Adenoviridae↗
PubMed1999

Approaches to enhance expression after adenovirus-mediated gene transfer to the carotid artery.

The goal of this study was to enhance transgene expression after adenoviral-mediated gene transfer to the carotid artery. We used an adenoviral vector with a transgene that expresses beta-galactosidase, driven by the human cytomegalovirus (CMV) promoter/enhancer. The CMV promoter drives constitutive expression, and response elements within the enhancer allow inducible expression through binding of active transcription factors, such as cAMP response element binding protein (CREB) and nuclear factor kappa B (NFkappaB). Rings of rabbit carotid artery were incubated ex vivo with a replication-deficient adenovirus that expresses beta-galactosidase (AdCMV-betagal). Virus was removed from the medium, and forskolin or phorbol-12-myristate-13-acetate (PMA), which can induce activation of CREB or NFkappaB, respectively, were added to the medium. Pyrrolidine dithiocarbamate (PDTC) was used to inhibit activation of NFkappaB. Following incubation for 24 hours, beta-galactosidase activity was assessed by chemiluminescent reporter assay. Forskolin and PMA enhanced transgene expression in the carotid artery. Activity increased from 56+/-13 mU/mg protein (mean+/-SE) in rings of carotid treated with virus alone (10(9) pfu) to 159+/-23 mU/mg protein (P<0.05) in rings treated with forskolin, and to 189+/-40 mU/mg protein (P<0.05) in rings treated with PMA. Phorbol didecanoate, an inactive phorbol, did not affect expression of beta-galactosidase. After pre-incubation with PDTC prior to PMA, expression of beta-galactosidase was less than in rings incubated with PMA alone (29+/-11, P<0.05). Histochemical staining of carotid artery for beta-galactosidase demonstrated enhanced endothelial expression following administration of PMA. These findings suggest that expression after gene transfer to the carotid artery using an adenoviral vector with the CMV promoter/enhancer may be enhanced by PMA and forskolin, perhaps by activation of transcription factors.

Activating Transcription Factor 1↗
PubMed1998

Evidence that macrophages in atherosclerotic lesions contain angiotensin II.

BACKGROUND: We have reported that human mononuclear leukocytes contain large amounts of angiotensin II (Ang II). The goal of the present study was to test the hypothesis that Ang II is present in monocyte/macrophages in atherosclerotic lesions. METHODS AND RESULTS: Segments of thoracic aorta and left circumflex coronary artery were obtained from 3 groups of cynomolgus monkeys: normal, atherosclerotic, and regression. Samples of human coronary arterial atherosclerotic lesions were obtained from directional atherectomy. Sections were stained for Ang II with 3 different polyclonal rabbit anti-human Ang II antisera. In aorta and coronary arteries from normal monkeys, there was no or minimal anti-Ang II staining in endothelial cells. All sections from atherosclerotic monkeys displayed discrete, localized regions of staining for Ang II in intima-media. Macrophages were present throughout the atherosclerotic intima-media, and anti-Ang II staining appeared to colocalize with macrophages. All human coronary atherectomy samples stained positive for Ang II and macrophages. Staining for both Ang II and macrophages was observed in vascular lesions from all 5 monkeys after regression of atherosclerosis, but staining was less extensive than in atherosclerotic blood vessels from monkeys. CONCLUSIONS: These findings suggest that Ang II is present in atherosclerotic lesions in monkeys and humans, colocalizes with macrophages in intima-media of atherosclerotic vessels from monkeys, and decreases in lesions in monkeys with regression of atherosclerosis.

Angiotensin II↗
PubMed1998

Overexpression of human superoxide dismutase inhibits oxidation of low-density lipoprotein by endothelial cells.

Oxidation of LDL in the subendothelial space has been proposed to play a key role in atherosclerosis. Endothelial cells produce superoxide anions (O2.-) and oxidize LDL in vitro; however, the role of O2.- in endothelial cell-induced LDL oxidation is unclear. Incubation of human LDL (200 microg/mL) with bovine aortic endothelial cells (BAECs) for 18 hours resulted in a 4-fold increase in LDL oxidation compared with cell-free incubation (22.5+/-1.1 versus 6.3+/-0.2 [mean+/-SEM] nmol malondialdehyde/mg LDL protein, respectively; P<0.05). Under similar conditions, incubation of LDL with porcine aortic endothelial cells resulted in a 5-fold increase in LDL oxidation. Inclusion of exogenous copper/zinc superoxide dismutase (Cu/ZnSOD, 100 microg/mL) in the medium reduced BAEC-induced LDL oxidation by 79%. To determine whether the intracellular SOD content can have a similar protective effect, BAECs were infected with adenoviral vectors containing cDNA for human Cu/ZnSOD (AdCu/ZnSOD) or manganese SOD (AdMnSOD). Adenoviral infection increased the content and activity of either Cu/ZnSOD or MnSOD in the cells and reduced cellular O2.- release by two thirds. When cells infected with AdCu/ZnSOD or AdMnSOD were incubated with LDL, formation of malondialdehyde was decreased by 77% and 32%, respectively. Two other indices of LDL oxidation, formation of conjugated dienes and increased LDL electrophoretic mobility, were similarly reduced by SOD transduction. These data suggest that production of O2.- contributes to endothelial cell-induced oxidation of LDL in vitro. Furthermore, adenovirus-mediated transfer of cDNA for human SOD, particularly Cu/ZnSOD, effectively reduces oxidation of LDL by endothelial cells.

Adenoviridae↗
PubMed1998

Superoxide production in vascular smooth muscle contributes to oxidative stress and impaired relaxation in atherosclerosis.

The endothelium is a source of reactive oxygen species in short-term models of hypercholesterolemia and atherosclerosis. We examined a chronic model of atherosclerosis for increased vascular production of superoxide (O2-.) and determined whether endothelial overexpression of superoxide dismutase (SOD) would improve endothelium-dependent relaxation. Superoxide generation was 3 times higher in isolated aortas from Watanabe heritable hyperlipidemic (WHHL) rabbits (2 to 4 years old) compared with aortas from New Zealand White (NZ) rabbits (43+/-10 versus 14+/-2 relative light units x min(-1) x mm(-2), n=9, P<0.05). After in vitro transduction with adenovirus containing the gene for CuZn-SOD (AdCMVCuZn-SOD) or extracellular SOD (AdCMVEC-SOD), endothelial O2-. levels in WHHL aortas were significantly reduced. Gene transfer of SOD to WHHL aortas, however, failed to improve the impaired relaxation to acetylcholine or calcium ionophore. By use of the oxidative fluorescent dye hydroethidine, an in situ assay indicated markedly increased generation of O2-. throughout the wall of WHHL aorta, especially within layers of smooth muscle. This finding was confirmed by demonstrating increased O2-. levels in smooth muscle cells cultured from WHHL aorta. We conclude that elevated O2-. levels in atherosclerotic vessels are not confined to the endothelium but occur throughout the vascular wall, including smooth muscle cells. Reduction in endothelial O2-. levels is not sufficient to improve endothelium-dependent relaxation. Generation of reactive oxygen species within the media may contribute to vasomotor dysfunction in atherosclerosis.

Animals↗