APOE ?4 influences the pathological phenotype of Alzheimer's disease by favouring cerebrovascular over parenchymal accumulation of A? protein

Wilcock, G. K.; Chalmers, K.; Love, Seth

Abstract

The relative amounts of amyloid ?-protein (A?) in cerebral blood vessels and parenchyma vary considerably amongst patients with Alzheimer's disease (AD). Although several mechanisms have been proposed to explain this variability, the underlying genetic and environmental determinants are still unclear, as are the functional consequences. Polymorphisms in APOE, the gene for apolipoprotein E (ApoE), influence the risk of developing AD and of deposition of A? within the brain. We examined the relationship between the APOE genotype and the relative extent of accumulation of A? as plaques within the cerebral parenchyma and in cortical blood vessels in the form of cerebral amyloid angiopathy (CAA), in autopsy brain tissue from 125 AD cases and from 53 elderly, neurologically normal controls of which 19 had CAA without other neuropathological features of AD. In the AD cases, we also assessed whether the severity of CAA was related to the age of onset and duration of dementia, risk factors for atherosclerotic vascular disease, and histologically demonstrable cerebral in-farcts or foci of haemorrhage. The APOE genotype was determined by a standard polymerase chain reaction-based method. Paraffin sections of frontal, temporal and parietal lobes were immunolabelled for A? and the parenchymal A? load (total A? minus vessel-associated A?) was quantified by computer-assisted image analysis. CAA severity was scored for cortical and leptomeningeal vessels. The relevant clinical data were obtained from the database of the South West Brain Bank. In AD, we found the severity of CAA to be strongly associated with the number of ?4 alleles (P < 0.0001) but the parenchymal A? load to be independent of APOE genotype. Cases with severe CAA had a lower parenchymal A? load than had those with moderate CAA (P = 0.003). Neither the severity of CAA nor the parenchymal A? load correlated with age of onset, duration of disease or age at death, and the severity of CAA also did not correlate with the presence of cerebral infarcts or foci of haemorrhage. These findings indicate that possession of the APOE ?4 allele favours vascular over parenchymal accumulation of A? in AD. This may influence the pathogenesis of neurodegeneration in ?4-associated AD.

Citation

Wilcock, G. K., Chalmers, K., Wilcock, G., & Love, S. (2003). APOE ?4 influences the pathological phenotype of Alzheimer's disease by favouring cerebrovascular over parenchymal accumulation of A? protein. Neuropathology and Applied Neurobiology, 29(3), 231-238. https://doi.org/10.1046/j.1365-2990.2003.00457.x

• Journal Article Type: Article
• Publication Date: Jun 1, 2003
• Journal: Neuropathology and Applied Neurobiology
• Print ISSN: 0305-1846
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 29
• Issue: 3
• Pages: 231-238
• DOI: https://doi.org/10.1046/j.1365-2990.2003.00457.x
• Keywords: APOE epsilon4, Alzheimer's, cerebrovascular, parenchymal, Abeta protein
• Public URL: https://uwe-repository.worktribe.com/output/1071875
• Publisher URL: http://dx.doi.org/10.1046/j.1365-2990.2003.00457.x