Differentiation

iv cc are termed foam cells, and they comprise a significant proportion of atherosclerotic lesions [2]. The process of Journal of Surgical Research 171, e27–e31 (2011) doi:10.1016/j.jss.2011.06.033were consistently observed in clusters rather than as isolated cells. Conclusions. TLR4 is necessary for oxLDL-induced macrophage differentiation to foam cells. Macrophage been observed, however, that unregulated uptake of modified LDL by macrophages, combined with down-regulated efflux of lipids is one of the mechanisms un-derlying foam cell formation [3]. Mounting evidence supports the role of inflammatory signals in macrophage foam cell formation [4, 5]. Toll-like receptor 4 (TLR4), a cell-surface pattern recogni-tion receptor on macrophages, is expressed in human and murine lipid rich atherosclerotic plaques [6]. Toll-like receptors (TLRs) play a vital role in host defense 1 To whom correspondence and reprint requests should be ad-dressedatDepartmentofSurgery,DivisionofCardiothoracicSurgery