MMPs in gene- and protein-expression

I would like to thank Wilton and colleagues for their interesting article [1]. The presented data is not only important because it shows no differences in gene-expression of MMP-1, -2, -9 and TIMP-1, -2 between ascending aortic samples of patients with BAV and TAV, but it also demonstrates that there may be significant differences between gene- and protein-expression within the same tissue. This may be true because it is well known that there are significant differences in (protein) MMPs- expression between BAV and TAV aortas [2]. This shows that it is necessary to undergo both, gene (‘genome’)-and protein(‘proteome’)- expression analyses to reveal a basic understanding of pathomolecular mechanisms leading to aortic dilatation in BAV and TAV patients.

Surprisingly, Wilton and colleagues did not find significant differences in aortic root and ascending aortic dimensions between both patient groups, despite the fact that larger aortic dimensions in BAV are well established [3]. Such findings may question the aortic valve classification in either of both groups, and could explain why the authors did not find any differences in gene-expression. It often can be difficult to define an aortic valve, even intraoperatively, as ‘true’ congenital bicuspid, in particular if there are severe degenerative leaflet changes. In addition, it would be interesting to know where exactly the aortic specimens were excised because different aortic areas (root, STJ, ascending aorta, concave, convex etc.) may show alterations in gene- and protein-expression and could significantly influence further analyses. Nevertheless, I would like to congratulate Wilton and colleagues for their important study which may provide new insights into aortic diseases associated with BAV and TAV.

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