Immunohistochemical study of distribution of apolipoproteins E and D in human cerebral beta amyloid deposits

Several molecules are known to be closely associated with amyloid deposits in human brain. Among these, apolipoproteins such as apolipoproteins E (apo E) and J (apo J) have been found in two neuropathological hallmarks of Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA): senile plaques (SPs) and cerebrovascular amyloid. These apolipoproteins may be implicated in amyloid fibrillogenesis. Apo D is a multi ligand -multifunctional glycoprotein present in SPs, as we previously reported. The aim of this work is to study the link between immunolocalization of apo E and apo D in AD and CAA brains. Both apolipoproteins were found in all types of SPs, but apo E was observed more often than apo D in mature plaques. Whereas apo E is always located overlapping the arnyloid core, apo D seems to situate preferably around and near the amyloid. Immunohistochemistry revealed that these apolipoproteins behave differently in cerebral vessels. Apo E labeling in vessels appears mainly linked to amyloid deposits, whereas apo D shows a distribution almost opposite to that of apo E. This could be an indication of the different roles that each apolipoprotein plays in the pathogenesis of arnyloid deposition. (C) 2003 Elsevier Inc. All rights reserved.