MMP9 and atherosclerosis: Interestingly, in this study 27-hydroxycholesterol was found to enhance cell release of IL-8, IL-1β, and TNF-α and to upregulate matrix metalloproteinase-9 (MMP-9) via the TLR4/NF-κB-dependent pathway, a phenomenon that has been associated to atherosclerotic lesion worsening during the process of atherosclerosis [33].