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Inhibition of Notch1 signaling reduces abdominal aortic aneurysm in mice by attenuating macrophage-mediated inflammation.

ABSTRACT: Activation of inflammatory pathways plays a critical role in the development of abdominal aortic aneurysms (AAA). Notch1 signaling is a significant regulator of the inflammatory response; however, its role in AAA is unknown.In an angiotensin II-induced mouse model of AAA, activation of Notch1 signaling was observed in the aortic aneurysmal tissue of Apoe(-/-) mice, and a similar activation of Notch1 was observed in aneurysms of humans undergoing AAA repair. Notch1 haploinsufficiency significantly reduced the incidence of AAA in Apoe(-/-) mice in response to angiotensin II. Reconstitution of bone marrow-derived cells from Notch1(+/-);Apoe(-/-) mice (donor) in lethally irradiated Apoe(-/-) mice (recipient) decreased the occurrence of aneurysm. Flow cytometry and immunohistochemistry demonstrated that Notch1 haploinsufficiency prevented the influx of inflammatory macrophages at the aneurysmal site by causing defects in macrophage migration and proliferation. In addition, there was an overall reduction in the inflammatory burden in the aorta of the Notch1(+/-);Apoe(-/-) mice compared with the Apoe(-/-) mice. Last, pharmacological inhibition of Notch1 signaling also prevented AAA formation and progression in Apoe(-/-) mice.Our data suggest that decreased levels of Notch1 protect against the formation of AAA by preventing macrophage recruitment and attenuating the inflammatory response in the aorta.

SUBMITTER: Hans CP

PROVIDER: S-EPMC4467024 | biostudies-literature | 2012 Dec

REPOSITORIES: biostudies-literature

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Inhibition of Notch1 signaling reduces abdominal aortic aneurysm in mice by attenuating macrophage-mediated inflammation.

Hans Chetan P CP Koenig Sara N SN Huang Nianyuan N Cheng Jeeyun J Beceiro Susana S Guggilam Anuradha A Kuivaniemi Helena H Partida-Sánchez Santiago S Garg Vidu V

Arteriosclerosis, thrombosis, and vascular biology 20121018 12

<h4>Objective</h4>Activation of inflammatory pathways plays a critical role in the development of abdominal aortic aneurysms (AAA). Notch1 signaling is a significant regulator of the inflammatory response; however, its role in AAA is unknown.<h4>Methods and results</h4>In an angiotensin II-induced mouse model of AAA, activation of Notch1 signaling was observed in the aortic aneurysmal tissue of Apoe(-/-) mice, and a similar activation of Notch1 was observed in aneurysms of humans undergoing AAA ...[more]

PMID: 23087364

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Project description:Tumor necrosis factor (TNF) is elevated in human abdominal aortic aneurysms (AAA). Non-selective TNF inhibition has been linked to several severe side effects. Compounds that target the proinflammatory soluble TNF (solTNF) while preserving the immunomodulatory capabilities of transmembrane TNF (tmTNF) may prevent such side effects. We hypothesize that inhibition of solTNF signaling by XPro1595 is just as effective as non-selective TNF inhibition by etanercept (ETN) in preventing AAA expansion. The effect of XPro1595 and ETN was examined in porcine pancreatic elastase (PPE) induced AAA mice and findings of XPro1595 was confirmed in Angiotensin II (AngII) induced AAA in hyperlipidemic apolipoprotein E (Apoe) -/- mice. XPro1595 treatment significantly reduced AAA expansion in both models, while a similar trend (p=0.06) was observed in ETN-treated mice using the PPE model. In the PPE aneurysm wall, elastin integrity scores were significantly improved in the XPro1595 group. In the aneurysms, mean TNFR1wasreduced no-significantly (p=0.07) by 50% non-significant after TNF inhibition, but the cellular location in murine AAAs were unaffected and like the localization in human AAAs. Systemic TNF levels were elevated in XPro1595-treated mice, while systemic IL-10 levels were significantly increased after ETN-treatment, while in AngII induced AAA mice systemic TNF and IL5 levels were elevated after XPro1595 treatment. In early AAA development, proteomic analyses revealed that components of the fibrinogen complex were elevated while prostaglandin E2 synthase was down regulated by Xpro1595 (unadjusted p-values). David’s ontology analyses revealed that several pathways including cell matrix adhesion, extracellular space, fibrinogen complex, blood microparticles and glycoproteins were elevated by XPro1595 treatment. In conclusion, selective inhibition of solTNF reduces aneurysm expansion. This supports targeting solTNF as an attractive treatment option for AAA patients.

Project description:BackgroundTumor necrosis factor (TNF) is pathologically elevated in human abdominal aortic aneurysms (AAA). Non-selective TNF inhibition-based therapeutics are approved for human use but have been linked to several side effects. Compounds that target the proinflammatory soluble form of TNF (solTNF) but preserve the immunomodulatory capabilities of the transmembrane form of TNF (tmTNF) may prevent these side effects. We hypothesize that inhibition of solTNF signaling prevents AAA expansion.MethodsThe effect of the selective solTNF inhibitor, XPro1595, and the non-selective TNF inhibitor, Etanercept (ETN) was examined in porcine pancreatic elastase (PPE) induced AAA mice, and findings with XPro1595 was confirmed in angiotensin II (ANGII) induced AAA in hyperlipidemic apolipoprotein E (Apoe) -/- mice.ResultsXPro1595 treatment significantly reduced AAA expansion in both models, and a similar trend (p = 0.06) was observed in PPE-induced AAA in ETN-treated mice. In the PPE aneurysm wall, XPro1595 improved elastin integrity scores. In aneurysms, mean TNFR1 levels reduced non-significantly (p = 0.07) by 50% after TNF inhibition, but the histological location in murine AAAs was unaffected and similar to that in human AAAs. Semi-quantification of infiltrating leucocytes, macrophages, T-cells, and neutrophils in the aneurysm wall were unaffected by TNF inhibition. XPro1595 increased systemic TNF levels, while ETN increased systemic IL-10 levels. In ANGII-induced AAA mice, XPro1595 increased systemic TNF and IL-5 levels. In early AAA development, proteomic analyses revealed that XPro1595 significantly upregulated ontology terms including "platelet aggregation" and "coagulation" related to the fibrinogen complex, from which several proteins were among the top regulated proteins. Downregulated ontology terms were associated with metabolic processes.ConclusionIn conclusion, selective inhibition of solTNF signaling reduced aneurysm expansion in mice, supporting its potential as an attractive treatment option for AAA patients.

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Inhibition of Notch1 signaling reduces abdominal aortic aneurysm in mice by attenuating macrophage-mediated inflammation.

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Inhibition of Notch1 signaling reduces abdominal aortic aneurysm in mice by attenuating macrophage-mediated inflammation.

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