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Inhibition of Marfan Syndrome Aortic Root Dilation by Losartan: Role of Angiotensin II Receptor Type 1-Independent Activation of Endothelial Function

Authors :
Stephanie L, Sellers
Nadia, Milad
Rayleigh, Chan
Michael, Mielnik
Una, Jermilova
Paul L, Huang
Rini, de Crom
Jeremy A, Hirota
James C, Hogg
George G, Sandor
Casey, Van Breemen
Mitra, Esfandiarei
Michael A, Seidman
Pascal, Bernatchez
Source :
The American journal of pathology. 188(3)
Publication Year :
2017

Abstract

Marfan syndrome (MFS) is a genetic disorder that frequently leads to aortic root dissection and aneurysm. Despite promising preclinical and pilot clinical data, a recent large-scale study using antihypertensive angiotensin II (AngII) receptor type 1 (ATR1) blocker losartan has failed to meet expectations at preventing MFS-associated aortic root dilation, casting doubts about optimal therapy. To study the deleterious role of normal ATR1 signaling in aortic root widening, we generated MFS mice lacking ATR1a expression in an attempt to preserve protective ATR2 signaling. Despite being hypotensive and resistant to AngII vasopressor effects, MFS/ATR1a-null mice showed unabated aortic root enlargement and remained fully responsive to losartan, confirming that blood pressure lowering is of minor therapeutic value in MFS and that losartan's antiremodeling properties may be ATR1 independent. Having shown that MFS causes endothelial dysfunction and that losartan can activate endothelial function in mice and patients, we found that nitric oxide synthase (NOS) inhibition renders losartan therapeutically inactive, whereas multiple transgenic and pharmacologic models of endothelial NOS activation block aortic root dilation by correcting extracellular signal-regulated kinase signaling. In vitro, losartan can increase endothelial NO release in the absence of AngII and correct MFS NO levels in vivo. Our data suggest that increased protective endothelial function, rather than ATR1 inhibition or blood pressure lowering, might be of therapeutic significance in preventing aortic root disease in MFS.

Details

ISSN :
15252191
Volume :
188
Issue :
3
Database :
OpenAIRE
Journal :
The American journal of pathology
Accession number :
edsair.pmid..........9d31b2e068ffcded01292453b354c1c9