• H H Clarice Yang, Jong Moo Kim, Elliott Chum, Cornelis van Breemen, and Ada W Y Chung.
• Department of Cardiovascular Science, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada.
• J. Thorac. Cardiovasc. Surg. 2010 Aug 1;140(2):305-312.e2.

ObjectiveLosartan potassium (INN losartan), an antihypertensive drug, has been shown to prevent thoracic aortic aneurysm in Marfan syndrome through the inhibition of transforming growth factor beta. Recently we reported that doxycycline, a nonspecific inhibitor of matrix metalloproteinases 2 and 9, normalized aortic vasomotor function and suppressed aneurysm growth. We hypothesized that a combination of losartan potassium and doxycycline would offer better secondary prevention treatment than would single-drug therapy to manage thoracic aortic aneurysm.MethodsA well-characterized mouse model of Marfan syndrome (Fbn1(C1039G/+)) was used. At 4 months of age, when aneurysm had established, mice (n = 15/group) were given doxycycline alone (0.24 g/L), losartan potassium alone (0.6 g/L), or combined (0.12-g/L doxycycline and 0.3-g/L losartan potassium) in drinking water. Littermate Fbn1(+/+) mice served as control. Thoracic aortas at 6 and 9 months were studied.ResultsAt 9 months, aortic diameter in untreated group was increased by 40% relative to control. Losartan potassium or doxycycline reduced aortic diameter by 10% to 16% versus untreated aortas. Losartan potassium and doxycycline combined completely prevented thoracic aortic aneurysm and improved elastic fiber organization, also downregulating matrix metalloproteinases 2 and 9 and transforming growth factor beta and normalizing aortic contractile and relaxation functions to control values.ConclusionsNeither losartan potassium nor doxycycline alone completely restored vascular integrity and cell function when given during delayed treatment, indicating the importance of timed pharmacologic intervention. Combined, however, they synergistically offered better aneurysm-suppressing effects than did single-drug medication in the secondary prevention of thoracic aortic aneurysm.Copyright 2010 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

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