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Pharmacologic blockade and genetic deletion of androgen receptor attenuates aortic aneurysm formation.

ABSTRACT: Testosterone is theorized to play a major role in the pathophysiology of abdominal aortic aneurysms (AAAs) because this disease occurs primarily in men. The role of the androgen receptor (AR) in the formation of AAAs has not been well elucidated, and therefore, it is hypothesized that androgen blockade will attenuate experimental aortic aneurysm formation.Aortas of 8- to 12-week-old male C57Bl/6 wild-type (WT) mice or male AR knockout (AR(-/-)) mice were perfused with purified porcine pancreatic elastase (0.35 U/mL) to induce AAA formation. Two groups of WT male mice were treated with the AR blockers flutamide (50 mg/kg) or ketoconazole (150 mg/kg) twice daily by intraperitoneal injection. Aortas were harvested on day 14 after video micrometry was used to measure AAA diameter. Cytokine arrays and histologic analysis were performed on aortic tissue. Groups were compared using an analysis of variance and a Tukey post hoc test.Flutamide and ketoconazole treatment (mean ± standard error of the mean) attenuated AAA formation in WT mice (84.2% ± 22.8% [P = .009] and 91.5% ± 18.2% [P = .037]) compared with WT elastase (121% ± 5.23%). In addition, AR(-/-) mice showed attenuation of AAA growth (64.4% ± 22.7%; P < .0001) compared with WT elastase. Cytokine arrays of aortic tissue revealed decreased levels of proinflammatory cytokines interleukin (IL)-?, IL-6, and IL-17 in flutamide-treated and AR(-/-) groups compared with controls.Pharmacologic and genetic AR blockade cause attenuation of AAA formation. Therapies for AR blockade used in prostate cancer may provide medical treatment to halt progression of AAAs in humans.

SUBMITTER: Davis JP

PROVIDER: S-EPMC4884130 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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Pharmacologic blockade and genetic deletion of androgen receptor attenuates aortic aneurysm formation.

Davis John P JP Salmon Morgan M Pope Nicolas H NH Lu Guanyi G Su Gang G Meher Akshaya A Ailawadi Gorav G Upchurch Gilbert R GR

Journal of vascular surgery 20160124 6

<h4>Background</h4>Testosterone is theorized to play a major role in the pathophysiology of abdominal aortic aneurysms (AAAs) because this disease occurs primarily in men. The role of the androgen receptor (AR) in the formation of AAAs has not been well elucidated, and therefore, it is hypothesized that androgen blockade will attenuate experimental aortic aneurysm formation.<h4>Methods</h4>Aortas of 8- to 12-week-old male C57Bl/6 wild-type (WT) mice or male AR knockout (AR(-/-)) mice were perfus ...[more]

PMID: 26817611

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Project description:BACKGROUND: Aortic aneurysm is a common but life-threatening disease among the elderly, for which no effective medical therapy is currently available. Activation of prostaglandin E(2) (PGE(2)) is known to increase the expression of matrix metalloproteinase (MMP) and the release of inflammatory cytokines, and may thus exacerbate abdominal aortic aneurysm (AAA) formation. We hypothesized that selective blocking of PGE(2), in particular, EP4 prostanoid receptor signaling, would attenuate the development of AAA. METHODS AND FINDINGS: Immunohistochemical analysis of human AAA tissues demonstrated that EP4 expression was greater in AAA areas than that in non-diseased areas. Interestingly, EP4 expression was proportional to the degree of elastic fiber degradation. In cultured human aortic smooth muscle cells (ASMCs), PGE(2) stimulation increased EP4 protein expression (1.4 ± 0.08-fold), and EP4 stimulation with ONO-AE1-329 increased MMP-2 activity and interleukin-6 (IL-6) production (1.4 ± 0.03- and 1.7 ± 0.14-fold, respectively, P<0.05). Accordingly, we examined the effect of EP4 inhibition in an ApoE(-/-) mouse model of AAA infused with angiotensin II. Oral administration of ONO-AE3-208 (0.01-0.5 mg/kg/day), an EP4 antagonist, for 4 weeks significantly decreased the formation of AAA (45-87% reduction, P<0.05). Similarly, EP4(+/-)/ApoE(-/-) mice exhibited significantly less AAA formation than EP4(+/+)/ApoE(-/-) mice (76% reduction, P<0.01). AAA formation induced by periaortic CaCl(2) application was also reduced in EP4(+/-) mice compared with wild-type mice (73% reduction, P<0.001). Furthermore, in human AAA tissue organ cultures containing SMCs and macrophages, doses of the EP4 antagonist at 10-100 nM decreased MMP-2 activation and IL-6 production (0.6 ± 0.06- and 0.7 ± 0.06-fold, respectively, P<0.05) without increasing MMP-9 activity or MCP-1 secretion. Thus, either pharmacological or genetic EP4 inhibition attenuated AAA formation in multiple mouse and human models by lowering MMP activity and cytokine release. CONCLUSION: An EP4 antagonist that prevents the activation of MMP and thereby inhibits the degradation of aortic elastic fiber may serve as a new strategy for medical treatment of AAA.

Project description:RATIONALE:Abdominal aortic aneurysms (AAAs) are a chronic inflammatory vascular disease for which pharmacological treatments are not available. A mouse model of AAA formation involves chronic infusion of angiotensin II (AngII), and previous studies indicated a primary role for the AngII type 1a receptor in AAA formation. ?-arrestin (?arr)-2 is a multifunctional scaffolding protein that binds G-protein-coupled receptors such as AngII type 1a and regulates numerous signaling pathways and pathophysiological processes. However, a role for ?arr2 in AngII-induced AAA formation is currently unknown. OBJECTIVE:To determine whether ?arr2 played a role in AngII-induced AAA formation in mice. METHODS AND RESULTS:Treatment of ?arr2(+/+) and ?arr2(-/-) mice on the hyperlipidemic apolipoprotein E-deficient (apoE(-/-)) background or on normolipidemic C57BL/6 background with AngII for 28 days indicated that ?arr2 deficiency significantly attenuated AAA formation. ?arr2 deficiency attenuated AngII-induced expression of cyclooxygenase-2, monocyte chemoattractant protein-1, macrophage inflammatory protein 1?, and macrophage infiltration. AngII also increased the levels of phosphorylated extracellular signal-regulated kinase 1/2 in apoE(-/-)/?arr2(+/+) aortas, whereas ?arr2 deficiency diminished this increase. Furthermore, inhibition of extracellular signal-regulated kinase 1/2 activation with CI1040 (100 mg/kg per day) reduced the level of AngII-induced cyclooxygenase-2 expression in apoE(-/-)/?arr2(+/+) mice to the level observed in apoE(-/-)/?arr2(-/-) mice. AngII treatment also increased matrix metalloproteinase expression and disruption of the elastic layer in apoE(-/-)/?arr2(+/+) aortas, and ?arr2 deficiency reduced these effects. CONCLUSIONS:?arr2 contributes to AngII-induced AAA formation in mice by phosphorylated extracellular signal-regulated kinase 1/2-mediated cyclooxygenase-2 induction and increased inflammation. These studies suggest that for the AngII type 1a receptor, G-protein-independent, ?arr2-dependent signaling plays a major role in AngII-induced AAA formation.

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Pharmacologic blockade and genetic deletion of androgen receptor attenuates aortic aneurysm formation.

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Pharmacologic blockade and genetic deletion of androgen receptor attenuates aortic aneurysm formation.

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