Objectives: The study aims to explore the relationship between expressions of toll-like receptor 4 (TLR4) on peripheral blood monocytes, serum tumor necrosis factor-alpha (TNF-α) and matrix metalloproteinase-9 (MMP-9) in patients with acute coronary syndromes (ACS), and to investigate the possible mechanisms of Benazepril stabilizing atherosclerosis plaques.

Methods: 70 patients selected were randomly divided into Benazepril treatment group (35 patients) and regular treatment group (35 patients). Meanwhile, Stable angina pectoris (SAP) group of 32 patients and control group of 22 patients were also set up. With the help of flow-cytometry, expressions of TLR4 on peripheral blood monocytes of the four groups were analyzed and compared to show differences, correlations and changes of the above mentioned indicators. The concentration of TNF-α and MMP-9 in serum were measured by enzyme linked immunosorbent assay (ELISA).

Results: (1) Expressions of TLR4, levels of TNF-α and MMP-9 were increased and the rate was rising from the control group, to SAP group and then to ACS group. All these indicators in ACS group are significantly higher than those in other groups (P < 0.05). (ACS versus SAP, control; all (P < 0.05). (2) Multi-linear regression analysis indicates that there was a positive correlation between the expression level of TLR4 and serum levels of TNF-α and MMP-9 in patients with ACS (P < 0.01). (3) There is no significant differences between the expression level of TLR4 and serum levels of TNF-α and MMP-9 in Benazepril treatment group and regular treatment group before treatment (P > 0.05) while they all fell after treatment (P < 0.05). In addition, all the indicators decreased more greatly than the regular treatment group.

Conclusions: TLR4 on peripheral blood monocytes and serum TNF-α and MMP-9 in patients with coronary arteriosclerosis disease may be effective markers of the vulnerable plaque. Benazepril can inhibit over-expression of TLR4 and reduce serum levels of TNF-α and MMP-9, thus stabilize the vulnerable plaques and improve the condition of the patients with ACS.