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Sirt1 Deficiency and Increased Oxidative Stress are Associated to Accelerated Cardiovascular Remodeling in Hypertensive Mice Submitted to a Western Diet
vascular pro-inflammatory processes are unknown. This in vivo study investigated whether testosterone induces redox-sensitive leukocyte migration (LM). Wistar rats were treated with -7 testosterone (24h, 10 M, ip), in the absence and presence of pretreatment (4h) with flutamide (Flu, androgen receptor -5 antagonist, 10 M), apocynin (Apo, antioxidant/possible NADPH -4 -4 oxidase inhibitor, 10 M) or NS398 (COX2 inhibitor, 10 M). Mesenteric LM was assessed by intravital microscopy. Expression of NADPH oxidase subunits, COX2 and VCAM was assessed by immunoblot. NADPH oxidase activity was detected in isolated membrane-fraction dihydroethidium fluorescence. Testosterone increased LM (4.5±0.21 vs 1.51±0.1, n=12), an effect blocked by Flu (1.87±0,33), NS398 (0.86±0,19) and Apo (0,87±0,1). Testosterone increased expression of p22phox, NOX1 and VCAM (0.5 fold, n=5, p<0,05) and augmented NADPH oxidase activity (136% of control, p<0,05, n=6). These effects were inhibited by Flu, Apo and, of note, NS398 (p<0,05, n=4), indicating that COX2 may be upstream of NADPH oxidase. Our in vivo studies demonstrate that testosterone plays a role in vascular inflammation by enhancing LM. This effect is mediated through processes that involve COX2 and NADPH oxidase-driven ROS. Hence, testosterone may contribute to inflammatory processes in vascular oxidative stress-related pathologies, particularly CVD in males. Funding: FAPESP/CNPq. doi: 10.1016/j.freeradbiomed.2010.10.014
14 The Effects of Exposure Regimen and Age on Chronic Ozone Exposure Induction of Atherosclerosis Gin C. Chuang1,2, Edward M. Postlethwait2,3, and Scott W. Ballinger1,2 1 2 Dept of Pathology, University of Alabama at Birmingham, Center for Free Radical Biology, University of Alabama at Birmingham, 3 Dept of Environmental Health Sciences, University of Alabama at Birmingham Ozone (O3) is a common air pollutant known to induce pulmonary oxidative stress, as well as exacerbate respiratory diseases such as asthma. Recent studies indicate that O3 inhalation may also confer increased risks of cardiovascular morbidity or mortality. We recently reported that 8 weeks of O3 exposure (5 O3 days/week; 40 total O3 days) significantly increased aortic intimal -/lesion size in the apoE mouse model of atherosclerosis, and that vascular oxidative stress markers increased significantly in C57Bl/6J mice after only 5 days of O3 exposure. Since the typical human exposure to O3 is intermittent, a 2 and 4 cycle exposure model was used in this follow-up study for increased physiological relevance; each cycle was 5 days of O3 followed by 9 days of -/filtered air. We hypothesized that apoE mice exposed to increased cycles of O3 will exhibit increased aortic atherosclerosis and oxidative stress, and the latter should normalize if the animals are allowed 5 days to recover without further exposures. Aortas of 4-cycle O3 exposed mice showed decreased aconitase activity and protein nitration, as well as increased SOD2 activity, but these alterations were not detected in the animals after 5 additional recovery days. These findings are consistent with our hypothesis that O3 exposure-induced vascular oxidative stress is transient and resolves after the exposure. We further observed that increased atherosclerosis induced by either 2 or 4 cycles of O3 exposure (10 and 20 total O3 days, respectively) was not statistically significant relative to controls, suggesting that the O3-/free days in each exposure cycle were protective. Lastly, apoE mice exposed to 3 weeks of O3 (5 O3 days/week; 15 total O3 days) starting at 5 days of age exhibited significantly increased aortic lesion size at 13 weeks of age versus controls, suggesting that young age at the time of O3 exposure may confer susceptibility. Conclusions: The nature of the O3 exposure regimen is critical in determining its atherogenic potential; transient vascular oxidative stress may play a role in O3-induced atherogenesis; and newborns may be more susceptible to the
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pro-atherogenic effects of O3 inhalation. doi: 10.1016/j.freeradbiomed.2010.10.015
15 Sirt1 Deficiency and Increased Oxidative Stress are Associated to Accelerated Cardiovascular Remodeling in Hypertensive Mice Submitted to a Western Diet Nicolas Clavreul1, Patricia Sansilvestri-morel1, Jérôme Paysant1, Olympe Beugné1, Christine Mauclair1, Tony J. Verbeuren1, and Alain Rupin1 1 Servier Research Institute To better understand the mechanism by which a Western diet can accelerate cardiovascular complications associated to hypertension, we set up a model of hypertensive mice receiving a high fat and high sucrose (HFHS) diet during 13 weeks. Double transgenic mice overexpressing human angiotensinogen and human renin (AGT/REN) have a moderate increase of their systolic blood pressure (+10 mmHg) compared to C57BL6. The HFHS diet slightly enhanced this difference (+15 mmHg). Fasting blood glucose concentration was higher in hypertensive mice under the HFHS diet compared to C57BL6 with the same diet (230 vs 188 mg/dl) and oral glucose tolerance tests confirmed that AGT/REN mice became more glucose intolerant. Although they reached the same body weight under the HFHS diet (21 g to 33 g), only the hypertensive mice showed a significant increase of heart weight that was correlated with an up-regulation of collagen I and alpha actin mRNA expression. In the aorta of AGT/REN mice under the HFHS diet, we found an increased TGFβ, Nox2 and CSF1-R mRNA expression, suggesting a macrophage infiltration, that was absent in the C57BL6 mice. Superoxide anion production in the aorta and nitrosyl hemoglobin in blood, a biomarker of NO synthesis, both measured by electron spin resonance, were consistent with an increased vascular oxidative stress with the HFHS diet. Interestingly, Sirt1, an important regulator of oxidative stress and glucose metabolism, was significantly reduced in the heart and the aorta of the animals under the HFHS diet. This study suggests that the diet-induced worsening of glucose tolerance, vascular inflammation and cardiac hypertrophy in hypertensive mice may be related to Sirt1 deficiency and increased oxidative stress. doi: 10.1016/j.freeradbiomed.2010.10.016
16 A Comparative Analysis of Diesel Exhaust Particulates with Varying Physicochemical Properties on Viability and Stress Response in Murine Endothelial Cells David P. Cox1,2, Bertram E. Drury3, and Terrance J. Kavanagh1,2 1 2 University of Washington, Center for Ecogenetics & 3 Environmental Health, University of Missouri Human exposure to traffic-related air pollution, specifically ultrafine ambient particulate matter (PM), has been associated with increased risk for cardiovascular dysfunction. Epidemiologic studies have further increased the complexity of PM-related cardiovascular dysfunction by identifying numerous variables such as proximity to traffic density in addition to particle source, size, and physicochemical properties. Diesel Exhaust particles (DEP) are a major component of urban-generated PM and DEP exposure has been associated with increased reactive oxygen species (ROS), which, depending on the levels can influence cellular function and/or toxicity. Endothelial cells are sensitive to increased ROS and their dysfunction has been implicated in several pathologies including hypertension and atherosclerosis.
SFRBM/SFRRI 2010
14 The Effects of Exposure Regimen and Age on Chronic Ozone Exposure Induction of Atherosclerosis Gin C. Chuang1,2, Edward M. Postlethwait2,3, and Scott W. Ballinger1,2 1 2 Dept of Pathology, University of Alabama at Birmingham, Center for Free Radical Biology, University of Alabama at Birmingham, 3 Dept of Environmental Health Sciences, University of Alabama at Birmingham Ozone (O3) is a common air pollutant known to induce pulmonary oxidative stress, as well as exacerbate respiratory diseases such as asthma. Recent studies indicate that O3 inhalation may also confer increased risks of cardiovascular morbidity or mortality. We recently reported that 8 weeks of O3 exposure (5 O3 days/week; 40 total O3 days) significantly increased aortic intimal -/lesion size in the apoE mouse model of atherosclerosis, and that vascular oxidative stress markers increased significantly in C57Bl/6J mice after only 5 days of O3 exposure. Since the typical human exposure to O3 is intermittent, a 2 and 4 cycle exposure model was used in this follow-up study for increased physiological relevance; each cycle was 5 days of O3 followed by 9 days of -/filtered air. We hypothesized that apoE mice exposed to increased cycles of O3 will exhibit increased aortic atherosclerosis and oxidative stress, and the latter should normalize if the animals are allowed 5 days to recover without further exposures. Aortas of 4-cycle O3 exposed mice showed decreased aconitase activity and protein nitration, as well as increased SOD2 activity, but these alterations were not detected in the animals after 5 additional recovery days. These findings are consistent with our hypothesis that O3 exposure-induced vascular oxidative stress is transient and resolves after the exposure. We further observed that increased atherosclerosis induced by either 2 or 4 cycles of O3 exposure (10 and 20 total O3 days, respectively) was not statistically significant relative to controls, suggesting that the O3-/free days in each exposure cycle were protective. Lastly, apoE mice exposed to 3 weeks of O3 (5 O3 days/week; 15 total O3 days) starting at 5 days of age exhibited significantly increased aortic lesion size at 13 weeks of age versus controls, suggesting that young age at the time of O3 exposure may confer susceptibility. Conclusions: The nature of the O3 exposure regimen is critical in determining its atherogenic potential; transient vascular oxidative stress may play a role in O3-induced atherogenesis; and newborns may be more susceptible to the
S18
pro-atherogenic effects of O3 inhalation. doi: 10.1016/j.freeradbiomed.2010.10.015
15 Sirt1 Deficiency and Increased Oxidative Stress are Associated to Accelerated Cardiovascular Remodeling in Hypertensive Mice Submitted to a Western Diet Nicolas Clavreul1, Patricia Sansilvestri-morel1, Jérôme Paysant1, Olympe Beugné1, Christine Mauclair1, Tony J. Verbeuren1, and Alain Rupin1 1 Servier Research Institute To better understand the mechanism by which a Western diet can accelerate cardiovascular complications associated to hypertension, we set up a model of hypertensive mice receiving a high fat and high sucrose (HFHS) diet during 13 weeks. Double transgenic mice overexpressing human angiotensinogen and human renin (AGT/REN) have a moderate increase of their systolic blood pressure (+10 mmHg) compared to C57BL6. The HFHS diet slightly enhanced this difference (+15 mmHg). Fasting blood glucose concentration was higher in hypertensive mice under the HFHS diet compared to C57BL6 with the same diet (230 vs 188 mg/dl) and oral glucose tolerance tests confirmed that AGT/REN mice became more glucose intolerant. Although they reached the same body weight under the HFHS diet (21 g to 33 g), only the hypertensive mice showed a significant increase of heart weight that was correlated with an up-regulation of collagen I and alpha actin mRNA expression. In the aorta of AGT/REN mice under the HFHS diet, we found an increased TGFβ, Nox2 and CSF1-R mRNA expression, suggesting a macrophage infiltration, that was absent in the C57BL6 mice. Superoxide anion production in the aorta and nitrosyl hemoglobin in blood, a biomarker of NO synthesis, both measured by electron spin resonance, were consistent with an increased vascular oxidative stress with the HFHS diet. Interestingly, Sirt1, an important regulator of oxidative stress and glucose metabolism, was significantly reduced in the heart and the aorta of the animals under the HFHS diet. This study suggests that the diet-induced worsening of glucose tolerance, vascular inflammation and cardiac hypertrophy in hypertensive mice may be related to Sirt1 deficiency and increased oxidative stress. doi: 10.1016/j.freeradbiomed.2010.10.016
16 A Comparative Analysis of Diesel Exhaust Particulates with Varying Physicochemical Properties on Viability and Stress Response in Murine Endothelial Cells David P. Cox1,2, Bertram E. Drury3, and Terrance J. Kavanagh1,2 1 2 University of Washington, Center for Ecogenetics & 3 Environmental Health, University of Missouri Human exposure to traffic-related air pollution, specifically ultrafine ambient particulate matter (PM), has been associated with increased risk for cardiovascular dysfunction. Epidemiologic studies have further increased the complexity of PM-related cardiovascular dysfunction by identifying numerous variables such as proximity to traffic density in addition to particle source, size, and physicochemical properties. Diesel Exhaust particles (DEP) are a major component of urban-generated PM and DEP exposure has been associated with increased reactive oxygen species (ROS), which, depending on the levels can influence cellular function and/or toxicity. Endothelial cells are sensitive to increased ROS and their dysfunction has been implicated in several pathologies including hypertension and atherosclerosis.
SFRBM/SFRRI 2010