Background: NK2 homeobox 5 (Nkx2-5) is a cardiac homeobox transcription factor that is expressed in a broad range of cardiac sublineages. Embryos lacking Nkx2-5 are nonviable attributed to growth retardation and gross abnormalities of the heart. However, the role of Nkx2-5 in atherosclerosis remains elusive. This study aims to elucidate the specific functions of Nkx2-5 during atherogenesis and in established atherosclerotic plaques.
Methods and results: Two types of atherosclerotic lesions were created in ApoE-/- mice through 2 different dietary manipulations. Mice fed a standard chow diet were sacrificed at 20 weeks old, a time point at which mice developed early-stage atherosclerotic lesions. The other half of mice were fed a western diet from 6 to 22 weeks old and then sacrificed. These mice demonstrated advanced atherosclerosis. No Nkx2-5 was detected in normal arteries; however, it was abundantly present in the intima of atherosclerotic lesions and localized in macrophages and smooth muscle cells. Adenovirus gene transfer of Nkx2-5 markedly ameliorated and stabilized the atherosclerotic plaques, and knockdown of Nkx2-5 significantly exacerbated the disease. Molecular studies indicated that expression of specific members of matrix metalloproteinases and tissue inhibitor of metalloproteinases, which play a crucial role in the progression of atherosclerosis, were directly regulated by Nkx2-5. Furthermore, we demonstrated that the compromised endothelial function, which was considered as a hallmark of early atherosclerosis, could be improved by Nkx2-5 gene transfer.
Conclusions: Nkx2-5 exerts antiatherogenic effects, which may partly be attributed to regulation on matrix metalloproteinases and tissue inhibitor of metalloproteinases, thus stabilizing atherosclerotic plaque; besides, it improves endothelial function by inhibiting leukocyte adhesion to the endothelium.
Keywords: NK2 homeobox 5; atherosclerosis; matrix metalloproteinases; plaque stability.
© 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.