Abstract:Objective Matrix metalloproteinase-9 (MMP-9), a metalloproteinase, is capable of degrading type IV, V collagens, as well as gelatins. Increased levels of MMP-9 have been detected in aortic aneurysms in adult human, suggesting its role in arterial wall destruction and aneurysm formation. This study was designed to investigate the potential role of MMP-9 in the pathogenesis of coronary artery lesions in Kawasaki disease (KD) patients. Methods Twenty-seven children with KD [17 with coronary artery lesions (CALs) and 10 without] and age-matched 10 febrile and 10 healthy controls were enrolled in this study. Gelatin zymography and ELISA were used to detect the activity and levels of serum MMP-9. MMP-9 mRNA expression in the leucocytes was detected using reverse transcription-polymerase chain reaction (RT-PCR). Results 1) The activity ( 10.2± 2.2) and levels of MMP-9 (1 116 ±691 ng/ml) in KD patients with CALs in the acute phase were significantly higher than those without CALs ( 6.2± 2.1, 457±133 ng/ml, respectively; P< 0.05). Both of them in either the KD patients with CALs or without were higher than those of the healthy controls ( 0.1± 0.0, 72±24 ng/ml, respectively; P< 0.01) and the febrile controls ( 3.1± 1.4, 221±154 ng/ml, respectively; P< 0.05). 2) There was a significantly positive correlation between the serum MMP-9 protein levels and the circulating leucocytes counts in KD patients in the acute phase (r= 0.480, P< 0.05). 3) The MMP-9 mRNA expression in the leucocytes of KD patients in the acute phase were significantly elevated, as compared with the febrile and healthy controls (P< 0.01). There were no significant differences in the MMP-9 mRNA expressions between the two KD groups. 4) The activity, protein levels and mRNA expression of MMP-9 in the KD patients decreased obviously from the subacute through the convalescent phases, as compared with the acute phase (P< 0.01). Conclusions The MMP-9 expression in KD patients in the acute phase was significantly elevated, especially in those with CALs. MMP-9 may be involved in the development of coronary artery lesions in KD.
