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Brain-targeted angiotensin-converting enzyme 2 overexpression attenuates neurogenic hypertension by inhibiting cyclooxygenase-mediated inflammation.

ABSTRACT: Overactivity of the renin-angiotensin system, oxidative stress, and cyclooxygenases (COX) in the brain are implicated in the pathogenesis of hypertension. We previously reported that angiotensin-converting enzyme 2 (ACE2) overexpression in the brain attenuates the development of deoxycorticosterone acetate-salt hypertension, a neurogenic hypertension model with enhanced brain renin-angiotensin system and sympathetic activity. To elucidate the mechanisms involved, we investigated whether oxidative stress, mitogen-activated protein kinase signaling and cyclooxygenase (COX) activation in the brain are modulated by ACE2 in neurogenic hypertension. Deoxycorticosterone acetate-salt hypertension significantly increased expression of Nox-2 (+61±5%), Nox-4 (+50±13%), and nitrotyrosine (+89±32%) and reduced activity of the antioxidant enzymes, catalase (-29±4%) and superoxide dismutase (-31±7%), indicating increased oxidative stress in the brain of nontransgenic mice. This increased oxidative stress was attenuated in transgenic mice overexpressing ACE2 in the brain. Deoxycorticosterone acetate-salt-induced reduction of neuronal nitric oxide synthase expression (-26±7%) and phosphorylated endothelial nitric oxide synthase/total endothelial nitric oxide synthase (-30±3%), and enhanced phosphorylation of protein kinase B and extracellular signal-regulated kinase 1/2 in the paraventricular nucleus, were reversed by ACE2 overexpression. In addition, ACE2 overexpression blunted the hypertension-mediated increase in gene and protein expression of COX-1 and COX-2 in the paraventricular nucleus. Furthermore, gene silencing of either COX-1 or COX-2 in the brain, reduced microglial activation and accompanied neuroinflammation, ultimately attenuating Deoxycorticosterone acetate-salt hypertension. Together, these data provide evidence that brain ACE2 overexpression reduces oxidative stress and COX-mediated neuroinflammation, improves antioxidant and nitric oxide signaling, and thereby attenuates the development of neurogenic hypertension.

SUBMITTER: Sriramula S

PROVIDER: S-EPMC4326547 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature

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Brain-targeted angiotensin-converting enzyme 2 overexpression attenuates neurogenic hypertension by inhibiting cyclooxygenase-mediated inflammation.

Sriramula Srinivas S Xia Huijing H Xu Ping P Lazartigues Eric E

Hypertension (Dallas, Tex. : 1979) 20141208 3

Overactivity of the renin-angiotensin system, oxidative stress, and cyclooxygenases (COX) in the brain are implicated in the pathogenesis of hypertension. We previously reported that angiotensin-converting enzyme 2 (ACE2) overexpression in the brain attenuates the development of deoxycorticosterone acetate-salt hypertension, a neurogenic hypertension model with enhanced brain renin-angiotensin system and sympathetic activity. To elucidate the mechanisms involved, we investigated whether oxidativ ...[more]

PMID: 25489058

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Project description:Evolution of glomerulonephritis (GN) to tubulointerstitial disease is a universal antecedent to the development of chronic kidney disease (CKD). There is also evidence that angiotensin converting enzyme (ACE) inhibition may attenuate the development of CKD in some forms of glomerulonephritis. We tested the role of ACE inhibition in a model of GN in which complement-dependent tubulointerstitial disease develops. GN was induced in C57BL/6 mice with intraperitoneal injections of horse spleen apoferritin (HSA) using lipopolysaccharide (LPS) as an adjuvant. Four groups of six animals were studied: saline-injected control mice treated with captopril or water, and GN mice treated with captopril or water. GN developed in all HSA-treated animals. In those receiving captopril, however, proteinuria (albumin/creatinine ratio) was significantly reduced by captopril treatment. Array screening was used to examined the expression of collagen-related genes and determine if these effects could be mediated by regulation of collagen genes. Six genes were identified for further analysis by quantitative RT-PCR. This model demonstrates that tubulointerstitial disease can be attenuated by ACE inhibition, with clinical, histologic, and gene expression measures. All protocols were approved by the Institutional Animal Care and Use Committee at SUNY Upstate Medical University. We employed four groups of six mice each: saline-injected control mice with and without captopril, and GN with and without captopril. C57BL/6 mice were purchased from The Jackson Laboratories (Bar Harbor, ME). Glomerulonephritis (GN) was induced by intraperitoneal (i.p.) injection of 10 mg of apoferritin from horse spleen (HSA, Sigma, St. Louis, MO) five days per week, with i.p. injection of 100 micrograms lipopolysaccharide (LPS, from Salmonella minnesota; EMD Biosciences, La Jolla, CA), as adjuvant, three times per week. Control animals received equal volumes of 0.15 M NaCl by i.p. injection. Injections were begun when the mice were approximately eight weeks of age and were continued for six weeks. Captopril, at 100 mg/kg/day was given in the drinking water. After 9 weeks, the animals were euthanized and kidneys were removed for RNA purification and analysis.

Dataset Information

Brain-targeted angiotensin-converting enzyme 2 overexpression attenuates neurogenic hypertension by inhibiting cyclooxygenase-mediated inflammation.

Publications

Brain-targeted angiotensin-converting enzyme 2 overexpression attenuates neurogenic hypertension by inhibiting cyclooxygenase-mediated inflammation.

Similar Datasets

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