Key result
Emilin1 deficiency in mice results in early postnatal cell-matrix defects, including elastic fiber fragmentation and aberrant angiogenesis, that progress to latent fibrotic aortic valve disease.
Emilin1 deficiency in mice recapitulates human fibrotic aortic valve disease, highlighting elastic fiber fragmentation and aberrant angiogenesis as potential therapeutic targets.
Establishes Emilin1-deficient mice as a model of fibrotic aortic valve disease; leaves open whether elastic fiber or angiogenesis targets will translate clinically.
Aortic valve disease (AVD) is characterized by elastic fiber fragmentation (EFF), fibrosis and aberrant angiogenesis. Emilin1 is an elastin-binding glycoprotein that regulates elastogenesis and inhibits TGF-β signaling, but the role of Emilin1 in valve tissue is unknown. We tested the hypothesis that Emilin1 deficiency results in AVD, mediated by non-canonical (MAPK/phosphorylated Erk1 and Erk2) TGF-β dysregulation. Using histology, immunohistochemistry, electron microscopy, quantitative gene expression analysis, immunoblotting and echocardiography, we examined the effects of Emilin1 deficiency (Emilin1-/-) in mouse aortic valve tissue. Emilin1 deficiency results in early postnatal cell-matrix defects in aortic valve tissue, including EFF, that progress to latent AVD and premature death. The Emilin1-/- aortic valve displays early aberrant provisional angiogenesis and late neovascularization. In addition, Emilin1-/- aortic valves are characterized by early valve interstitial cell activation and proliferation and late myofibroblast-like cell activation and fibrosis. Interestingly, canonical TGF-β signaling (phosphorylated Smad2 and Smad3) is upregulated constitutively from birth to senescence, whereas non-canonical TGF-β signaling (phosphorylated Erk1 and Erk2) progressively increases over time. Emilin1 deficiency recapitulates human fibrotic AVD, and advanced disease is mediated by non-canonical (MAPK/phosphorylated Erk1 and Erk2) TGF-β activation. The early manifestation of EFF and aberrant angiogenesis suggests that these processes are crucial intermediate factors involved in disease progression and therefore might provide new therapeutic targets for human AVD.
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Munjal et al. (2014) studied Aortic valve disease. Emilin1 deficiency was evaluated on Aortic valve disease progression (elastic fiber fragmentation, aberrant angiogenesis, fibrosis, premature death). Emilin1 deficiency in mice results in early postnatal cell-matrix defects, including elastic fiber fragmentation and aberrant angiogenesis, that progress to latent fibrotic aortic valve disease.
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