Aim To investigate the correlation between the protein expressions of matrix metalloproteinase-9(MMP-9),tissue inhibitor of metalloproteinase-1(TIMP-1) and phospho-c-Jun in peripheral blood mononuclear cells of patients with coronary heart disease and the characteristics of atherosclerosis plaque combined with the coronary angiography.Methods 55 patients who had coronary heart disease and underwent an immediate or selective coronary angiography(CAG) were selected and divided into 3 groups:acute coronary syndrome(ACS) group(n=24),stable angina(SA) group(n=16) and conrol group(n=15).MMP-9,TIMP-1 and phospho-c-Jun expressions in peripheral blood mononuclear cells were measured by Western-Blot.Coronary angiograms were scored according to Gensini integration and analysis of the relationship between MMP-9,TIMP-1,phospho-c-Jun,MMP-9/TIMP-1 and Gensini integration by linear correlation.Results ①MMP-9,TIMP-1,phospho-c-Jun and MMP-9/TIMP-1 were significantly increased in ACS group than those in SA group and control group(all P<0.001).②MMP-9,phospho-c-Jun and MMP-9/TIMP-1 were positively correlated with Gensini integration(separately r=0.433,r= 0.476,r=0.457,all P<0.01),but there was no correlation between TIMP-1 and Gensini integration.③MMP-9 was greatly correlated with phospho-c-Jun in patients with coronary heart disease(r=0.839,P<0.001).Conclusions ①MMP-9 and MMP-9/TIMP-1 were significantly increased but imbalanced in the patients with ACS,which suggested a prediction of more complex damage and more vulnerable plaque in coronary artery.②The activation of c-Jun may contribute to MMP-9 expression during the pathogenesis of atherosclerosis.