Objective To explore the association between extracellular matrix metalloproteinase inducer(EMMPRIN) and urokinase-type plasminogen activator (uPA) and the severity of coronary artery lesions in coronary heart disease (CHD) patients.Methods This study enrolled 88 patients with acute coronary syndrome (ACS) and 46 patients with stable angina pectoris (SAP).The mean fluorescence intensity (MFI) of EMMPRIN on monocytes of peripheral blood (PBMCs) were examined by flow cytometry.uPA in serum was measured with ELISA.64-slice spiral computed tomography coronary artery imaging was performed in 108 CHD patients.Coronary artery plaques were divided into type Ⅰ (33 patients),type Ⅱ (59 patients) and type Ⅲ (44 patients) through plaque morphology characteristics according to coronary angiography.Coronary artery plaques were divided into soft (42 patients),fibrous (34 patients) and calcified plaque (32 patients) according to CT characteristics.Results (1)Type Ⅱ plaque(48 patients)and soft plaque (35 patients) were the major plaque types in the ACS patients,while type Ⅰ plaque (20 patients) and type Ⅲ plaque (17 patients) and fibrous plaque (16 patients) and calcified plaque (22 patients)were the major plaque types in the SAP patients.(2)The EMMPRIN expression and uPA levels were significantly higher in type Ⅱ plaque group (EMMPRIN MFI:1 1.61 ± 0.81,uPA:(0.89 ± 0.17) mg/L) than those in the type Ⅰ plaque group (EMMPRIN MFI:6.65 ± 1.32,uPA:(0.53 ±0.06) mg/L) and in the type Ⅲ plaque group (EMMPRIN MFI:9.47 ± 1.16,uPA:(0.56 ±0.04) mg/L,all P ＜ 0.05).The EMMPRIN expression was higher in the type Ⅲ plaque group (MFI:9.47± 1.16)than in the type Ⅰ plaque group (MFI:6.65 ± 1.32,P ＜ 0.05),but uPA levels were similar between the 2 groups ((0.56 ± 0.04) mg/L vs.(0.53 ± 0.06) mg/L).(3) The EMMPRIN expression and uPA levels in the soft plaque group (EMMPRIN MFI:11.37 ± 0.76,uPA:(0.97 ± 0.12) mg/L) were significantly higher than those in the fibrous plaque group (EMMPRIN MFI:8.93 ± 1.21),uPA:(0.52 ±0.09) mg/L) and calcified plaque group (EMMPRIN MFI:6.94 ± 1.19,uPA:(0.49 ± 0.12) mg/L,P ＜0.05).The EMMPRIN expression in the fibrous plaque group(MFI:8.93 ± 1.21) was higher than in the calcified plaque group (MFI:6.94 ± 1.19,P ＜ 0.05),but uPA levels were similar between the two groups.Conclusion Higher EMMPRIN expression and uPA levels were associated with plaque instability,which might be used to evaluate plaque stability in CHD patients.