Although the three RNAi groups were effective in attenuating atherosclerotic plaque formation, the combined Lp-PLA2 and YKL-40 RNAi group exhibited lower lipid content, higher collagen content and fibrous cap thickness and reduced mRNA expression of MCP-1 and MMP-8 compared to Lp-PLA2 or YKL-40 RNAi alone, thus providing a potential therapeutic approach for the treatment of atherosclerosis. Here, MMP8 is linked to atherosclerosis.