Effects of Type I Collagen on the Uptake of Oxidized Low Density Lipoprotein by Macrophages

In order to investigate the influence of collagen on the uptake of oxidized low density lipoprotein (ox-LDL) by macrophages, a type I collagen gel-macrophages system was established in vitro. The binding of ox-LDL, malondialdehyde (MDA)-modified LDL and acetyl LDL to collagen was higher but the binding of 4-hydroxynonenal (HNE)-modified LDL was lower than that of native LDL. When mouse peritoneal macrophages were cultivated on the collagen gel, the uptake of ox-LDL decreased dramatically. Most of the modified (125)I-LDL were bound to the collagen gel rather than degraded by macrophages. If the cells were treated with cytochalasin D (an inhibitor of non-specific phagocytosis of macrophages), the degradation of ox-LDL by cells decreased markedly in the absence of collagen. However, the degradation of ox-LDL by cells showed little change in the presence of collagen. These results suggest that the non-specific phagocytosis of ox-LDL by macrophages might be prevented when type I collagen is present.