M2b macrophage subset decrement as an indicator of cognitive function in Alzheimer's disease.

AIM

Alzheimer's disease (AD) is a chronic neurodegenerative disease. Various inflammatory processes account for the pathology of AD, and macrophages in particular have a distinct polarization phenotype related to M1/M2 classification. We aimed to investigate macrophage polarization patterns as an indicator of cognitive function in AD.

METHODS

We recruited 54 non-demented individuals as control and 105 AD patients as experimental groups respectively. Percentages of macrophage (PM2K CD14 and PM2K CD14 ) and macrophage polarization subsets (M1, M2a, M2b, and M2c) were assessed using flow cytometry. All AD patients were classified by dementia severity using clinical Dementia Rating scale (CDR) as CDR 0.5, 1 and ≧2. AD patients had cognitive function evaluation using Mini-Mental State Examination (MMSE) and Cognitive Assessment Screening Instrument (CASI). We compared the macrophage polarization patterns between control and patient groups. Cognitive function was evaluated in association with macrophage polarization patterns in AD patients.

RESULTS

The percentages of PM2K CD14 and PM2K CD14 macrophages were higher in AD patients than in controls. M2b macrophage subset decrement and M1 macrophage subset increment of PM2K CD14 and PM2K CD14 macrophages were observed in AD patients compared with controls. Although percentages of macrophage subsets were not consistent with CDR staging, PM2K CD14 M2b macrophage subset decrement was correlated with worse cognitive functioning by MMSE and CASI in AD patients.

CONCLUSION

M2b macrophage subset decrement and M1 macrophage subset increment were noted in AD patients, while PM2K CD14 M2b macrophage subset decrement indicated worse cognitive function in such patients.