Elastolytic matrix metalloproteinases and coronary outcome in children with Kawasaki disease.

Kawasaki disease (KD) is a multisystem vasculitis that leads to coronary artery damage and aneurysm formation. Elastolytic matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of arterial aneurysms. To determine the relationship between circulating levels of elastolytic MMPs and development of coronary artery aneurysms in children with KD, we partnered studies done in affected children with an animal model of disease. In affected children, circulating protein levels and enzymatic activity of MMP-2 and MMP-9 did not have a statistically significant relationship with coronary artery outcome after adjusting for demographic characteristics, and clinical and laboratory features. Although matrix-degrading proteolytic activity was specific for affected mice and localized to inflamed coronary artery segments, the enzymatic activity in the systemic circulation of affected and control mice were not different. Similar to affected children, peripheral blood levels of MMP-9 enzymatic activity did not correlate with coronary artery disease in the animal model. Therefore, circulating levels of MMPs known to act locally may not be useful biomarkers of disease. This is especially relevant to enzymatic activity that is tightly regulated at multiple levels including the local tissue environment.