Osteopontin in the Pathogenesis of Aortic Dissection by the Enhancement of MMP Expressions.

The pathogenesis of aortic dissection (AD) is unclear. The aim of this study was to explore the relationship between osteopontin (OPN) and AD. Fifty AD patients were enrolled; 29 had hypertension with AD (H-AD) and 21 no hypertension with HD (NH-AD). Twenty-five healthy controls (NH-C) and 14 patients with hypertension (H-C) were also enrolled. Serum and aortic wall OPN levels were determined. Human vascular muscle cells (HVSMC) were stimulated by both low (1 μg/mL) and high (5 μg/mL) concentrations of OPN and cell proliferation as well as apoptosis was measured. Transforming growth factor-β (TGF-β), matrix metalloproteinase 1 (MMP-1), MMP-2, MMP-9, TIMP-1, and TIMP-2 gene expressions by HVSMC were measured and Akt, IκB, Smad1/5/8 and Erk1/2 signaling pathways were detected. Our results showed that AD patients demonstrated significantly higher levels of serum and local OPN expressions compared to healthy controls. In those with hypertension, the serum concentrations of OPN were increased compared to those without hypertension. In in vitro culture, a high dose of OPN stimulation promoted the proliferation of HVSMC but did not affect cell apoptosis. Both concentrations of OPN enhanced MMP-2 gene expression and its activity in HVSMC. Moreover, Akt and IκB signaling pathways were significantly activated after OPN stimulation while the Smad1/5/8 and Erk1/2 signaling pathways were not changed. The addition of an IκB inhibitor significantly abrogated MMP-2 gene expression. Our data show that OPN may participate in the pathogenesis of AD by the enhancement of MMP-2 expression.