Loss of ADAM15 in Female Mice Does Not Worsen Pressure Overload Cardiomyopathy, Independent of Ovarian Hormones.

Cardiac hypertrophy is a common feature in several cardiomyopathies. We previously reported that loss of ADAM15 (disintegrin and metalloproteinase 15) worsened cardiac hypertrophy and dilated cardiomyopathy following cardiac pressure overload. Here, we investigated the impact of ADAM15 loss in female mice following cardiac pressure overload induced by transverse aortic constriction (TAC). Female Adam15(-/-) mice developed the same degree of cardiac hypertrophy, dilation, and dysfunction as the parallel female wild-type (WT) mice at 6 wk post-TAC. To determine if this is due to the protective effects of estrogen, which could mask the negative impact of Adam15 loss, WT and Adam15(-/-) mice underwent ovariectomy (OVx) 2 wk before TAC. Cardiac structure and function analyses were performed at 6 wk post-TAC. OVx similarly impacted females of both genotypes post-TAC. Calcineurin (Cn) activity was increased post-OVx-TAC, and more in Adam15(-/-) mice; however, this increase was not reflected in the total-to-phospho-NFAT levels. Integrin-alpha(7) expression, which was upstream of Cn activation in male Adam15(-/-) -TAC mice, remained unchanged in female mice. However, activation of the mitogen-activated protein kinases (ERK, JNK, P38) was greater in Adam15(-/-)-OVx-TAC than in WT-OVx-TAC mice. In addition, ADAM15 protein levels were significantly increased post-TAC in male but not in female WT mice. Myocardial fibrosis was comparable in non-OVx WT-TAC and Adam15(-/-) -TAC mice. OVx increased the perivascular fibrosis more in Adam15(-/-) compared with WT mice post-TAC. Our data demonstrate that loss of ovarian hormones did not fully replicate the male phenotype in the female Adam15(-/-) mice post-TAC. As ADAM15 levels were increased in males but not in females post-TAC, it is plausible that ADAM15 does not play a prominent role in post-TAC events in female mice. Our findings highlight the significance of factors other than sex hormones in mediating cardiomyopathies in females, which require a more thorough understanding.