Peripheral inflammatory cytokines as biomarkers in Alzheimer's disease and mild cognitive impairment

Abstract

Background: Several lines of evidence in the literature have shown that inflammation is involved in the pathogenesis of Alzheimer's disease (AD). However, the results from the evaluation of serum inflammatory markers in AD patients have been controversial.

Objective: To determine if any differences exist in the monocytic secretion pattern of IL-1beta, IL-6, IL-12 and TNF-alpha from mild cognitive impairment (MCI) and AD patients, when compared with healthy age-matched controls.

Methods: To evaluate the percentage of peripheral monocytes secreting IL-1beta, IL-6, IL-12 and TNF-alpha along with the relative levels of these proteins, a cytofluorimetric analysis was conducted under basal conditions and after lipopolysaccharide-induced cell activation.

Results: We found, in AD and MCI patients, a significant raise in the percentage of monocytes producing the studied cytokines (under basal conditions and after the exposure to an inflammatory stimulus), as well as a decreased competence of these cells to respond to inflammatory challenges, when compared with controls.

Conclusions: These results agree with a persistent inflammatory status in AD, reinforcing the hypothesis of a progressive impairment of the immune response in this disorder and suggesting that monocytes may be good targets to study the progression from MCI to AD.