Blood levels of MCP-1 modulate the genetic risks of Alzheimer’s disease mediated by HLA-DRB1 and APOE for Alzheimer’s disease

Author(s): Huang, J; Stein, TD; Wang, Y; Ang, TFA; Tao, Q; Lunetta, KL; Massaro, J; Akhter-Khan, SC; Mez, J; Au, R; Farrer, LA; Zhang, X; Qiu, WQ; Alzheimer's Disease Neuroimaging Initiative;
Year: 2023;  
Journal: Alzheimer's & Dementia: The Journal of the Alzheimer's Association;  
Volume: 19;  
Issue: 5;  

INTRODUCTION: C-Reactive protein (CRP) and monocyte chemoattractant protein-1 (MCP-1) are both implicated in the peripheral proinflammatory cascade and blood-brain barrier (BBB) disruption. Since the blood CRP level increases Alzheimer’s disease (AD) risk depending on the apolipoprotein E (APOE) genotype, we hypothesized that the blood MCP-1 level exerts different effects on the AD risk depending on the genotypes.
METHODS: Using multiple regression analyses, data from the Framingham Heart Study (n = 2884) and Alzheimer’s Disease Neuroimaging Initiative study (n = 231) were analyzed.
RESULTS: An elevated blood MCP-1 level was associated with AD risk in major histocompatibility complex, Class II, DR beta 1 (HLA-DRB1) rs9271192-AC/CC (hazard ratio [HR] = 3.07, 95% confidence interval [CI] = 1.50-6.28, p = 0.002) and in APOE ε4 carriers (HR = 3.22, 95% CI = 1.59-6.53, p = 0.001). In contrast, among HLA-DRB1 rs9271192-AA and APOE ε4 noncarriers, blood MCP-1 levels were not associated with these phenotypes.
DISCUSSION: Since HLA-DRB1 and APOE are expressed in the BBB, blood MCP-1 released in the peripheral inflammatory cascade may function as a mediator of the effects of HLA-DRB1 rs9271192-AC/CC and APOE ε4 genotypes on AD pathogenesis in the brain via the BBB pathways.