Association of an interleukin-1β gene polymorphism at position -511 with Alzheimer's disease

Inflammation is thought to promote neuronal cell death in Alzheimer's disease (AD). The proinflammatory interleukin-1 is a main component in inflammatory pathways and is overexpressed in the brain of AD patients. Investigation of different polymorphisms in the interleukin-1 genes (IL-1α -889, IL-1β -511, IL-1β +3953) revealed associations between specific alleles and AD in that they increased the risk or modified the age at onset of AD. However, there are controversial findings from other studies which revealed no significant associations between these polymorphisms and AD; thus further evaluation of the association of IL-1 gene polymorphisms with AD and their role in pathogenesis is needed. In this study we examined the distribution of the IL-1β -511 alleles in AD patients and a control sample of healthy individuals. An additional control population of non-demented depressive inpatients was recruited to exclude a confounding bias. The cerebrospinal fluid (CSF) levels of Aβ42 in AD patients were investigated to assess the influence of IL-1β -511 genotypes. We found no significant association of the IL-1β -511 polymorphism with AD, suggesting that the IL-1β -511 polymorphism is no risk factor for AD. However, we found the Aβ42 CSF levels to be lower in carriers of the IL-1β CC-genotype compared to carriers of the T-allele. Even though IL-1β -511 polymorphism did not influence the risk of AD it might have a pathophysiological influence on the disease process.