Abstract
Aortic valve disease (AVD) is a common condition with a progressive natural history, and presently, there are no pharmacologic treatment strategies. Elastic fiber fragmentation (EFF) is a hallmark of AVD, and increasing evidence implicates developmental elastic fiber assembly defects. Emilin1 is a glycoprotein necessary for elastic fiber assembly that is present in both developing and mature human and mouse aortic valves. The Emilin1‐deficient mouse (Emilin1 −/−) is a model of latent AVD, characterized by activated TGFβ/MEK/p‐Erk signaling and upregulated elastase activity. Emilin1 −/− aortic valves demonstrate early EFF and aberrant angiogenesis followed by late neovascularization and fibrosis. The objective of this study was to test the effectiveness of three different targeted therapies. Aged (12–14 months) Emilin1 −/− mice were treated with refametinib (RDEA‐119, MEK1/2 inhibitor), doxycycline (elastase inhibitor), or G6‐31 (anti‐VEGF‐A mouse antibody) for 4 weeks. Refametinib‐ and doxycycline‐treated Emilin1 −/− mice markedly reduced MEK/p‐Erk activation in valve tissue. Furthermore, both refametinib and doxycycline attenuated elastolytic cathepsin K, L, MMP‐2, and MMP‐9 activation, and abrogated macrophage and neutrophil infiltration in Emilin1 −/− aortic valves. RNAseq analysis was performed in aortic valve tissue from adult (4 months) and aged (14 months) Emilin1 −/− and age‐matched wild‐type control mice, and demonstrated upregulation of genes associated with MAPK/MEK/p‐Erk signaling and elastases at the adult stage and inflammatory pathways at the aged stage controlling for age. These results suggest that Erk1/2 signaling is an important modulator of early elastase activation, and pharmacological inhibition using refametinib may be a promising treatment to halt AVD progression
Highlights
Aortic valve disease (AVD) is a common cause of cardiovascular morbidity and mortality (Mozaffarian et al 2015)
Animals were divided into five groups: (1) vehicle-treated Emilin1+/+ mice; (2) vehicle-treated Emilin1À/À mice; (3) Emilin1À/À mice treated with refametinib (RDEA-119), a selective MEK1/2 inhibitor (p-Erk1/2 inhibition); (4) Emilin1À/À mice treated with doxycycline; and (5) Emilin1À/À mice treated with G6-31 (Vegf-A inhibition) (Fig. 1)
These findings demonstrate that refametinib effectively suppresses p-Erk1/2 in diseased tissue and restores elastic fiber morphology
Summary
Aortic valve disease (AVD) is a common cause of cardiovascular morbidity and mortality (Mozaffarian et al 2015). There are no pharmacologic treatment options available for preventing, reversing, or halting the progression of AVD (Rajamannan et al 2011). There is a crucial need for new pharmacologic treatment options that stop AVD progression, precluding the need for a 2017 Cincinnati Children’s Hospital. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.
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