Oxidized-LDL induce the expression of heat shock protein 70 in human endothelial cells

Heat shock proteins are detectable in human atherosclerotic plaques, especially in endothelial cells. In this report we show by immunofluorescence that incubation "in vitro" with OxLDL is a stress capable of inducing the expression of heat shock protein 70 in both the EAhy-926 cell line and human umbilical vein endothelial cells (HUVEC). This induction was parallel to the cytotoxicity of oxidized LDL as determined by [3H]adenine release. When cells were confluent, however, both effects were greatly reduced. We speculate that induction of hsp70 is related to the cytotoxicity of oxidized LDL and that the detection of heat shock proteins in human atherosclerotic plaques is a further indication for the presence "in vivo" of oxidized LDL. These observations may be relevant to the understanding of endothelial response to injury in proatherosclerotic events.