Aluminum chloride pretreatment of elastin inhibits elastolysis by matrix metalloproteinases and leads to inhibition of elastin-oriented calcification

Calcification of elastin occurs in many pathological cardiovascular diseases including atherosclerosis. We have previously shown that purified elastin when subdermally implanted in rats undergoes severe calcification and aluminum chloride (AlCl3) pretreatment of elastin inhibits calcification. in the present study we investigated whether matrix metalloproteinase (MMP) binding to elastin and elastin degradation is prevented by AlCl3 pretreatment. Subdermal implantation of AlCl3-pretreated elastin showed significantly lower MMP-9 and MMP-2 activity surrounding the implant as compared to the control implants. AlCl3 pretreatment also significantly inhibited elastin implant calcification at the seven-day implant period (AlCl3-pretreated 4.07 +/- 1.27, control 23.82 +/- 2.24 mug/mg; p < 0.0001). Moreover, elastin gel zymography studies showed that gel pretreatment with AlCl3 inhibited elastolysis by MMP-9. We also demonstrate significant suppression of MMP-2 activity in aortic wall segments of AlCl3-pretreated porcine bioprosthetic heart valve implants as compared to control valve implants in sheep mitral valve replacement studies. AlCl3 pretreatment also significantly inhibited calcification of elastin in this model. Thus, we conclude that aluminum ion binding to elastin prevents MMP-mediated elastolysis and thus prevents elastin calcification.