Atherosclerosis alters the localization of HSP70 in human and macaque aortas

Evidence suggests an important role for heat shock proteins (HSPs) in the evolution of atherosclerotic necrotic cores. The present study compared normal-appearing and atherosclerotic aortas obtained from control and diet-induced atherosclerotic cynomolgus macaques and from human autopsies, with respect to the localization and content of 70-kDa HSPs (HSP70). The distribution pattern of HSP70 was determined by immunostaining tissue sections with anti-HSP70 monoclonal antibody against both constitutive and inducible isoforms. Changes in HSP70 staining with developing atherosclerosis were quantitated using video morphometry. Total aortic HSP70 content was evaluated by Western blotting tissue homogenates. In both macaque and human aortas, HSP70 staining was homogeneous in normal-appearing regions, but developed a heterogeneous pattern in the presence of atherosclerosis. Immunostaining for three other HSPs (90, 65, and 28 kDa) confirmed the change as HSP-specific. Video morphometry indicated a significant positive association between severity of atherosclerosis and altered patterns of HSP70 staining. However, Western blots detected no difference in total HSP70 content of either human or macaque aortas with plaque progression. The data suggest HSP70 localization changes in aortas during atherosclerosis evolution without affecting overall aortic HSP70 content. Such changes in HSP70 localization may reflect differences in the cellular response and resistance to cytotoxic conditions present within the plaque, which could influence the expansion of necrotic cores.