Correlation analysis of positive Alzheimer’s disease plasma biological markers with plasma immune cell and clinical characteristics in mild cognitive impairment patients in China

OBJECTIVE: The aim of the present work was to investigate the correlation between positive Alzheimer's disease (AD) plasma biological markers and plasma immune cell content as well as clinical characteristics in mild cognitive impairment (MCI) patients. METHODS: A total of 176 patients aged ≥ 65 years with MCI were followed up for two years. At baseline, AD plasma biomarkers (Aβ42, Aβ40, Aβ42/40, P-tau181 and PTau217) and immune cells (Treg cells, TH17 cells, lymphocytes) in MCI patients were detected, and their relevant clinical characteristics were recorded. Finally, the correlation between positive AD plasma biomarkers and immune cells, relevant clinical characteristics of MCI patients, and whether they would progress was analyzed. RESULTS: Plasma Aβ42/40 levels are negatively correlated with age, a history of hypertension, constipation symptoms, and the TGF-β/Treg cell ratio. They are positively correlated with the TIM3+/Treg cell ratio, the number of CD19-positive cells, the CD4/CD8 ratio, and the number of CD8-positive cells. Plasma PTau217 levels are positively correlated with age, the proportion of B cells, and the proportion of NK cells, and negatively correlated with visual-spatial executive function and attention cognitive domain scores. Dual abnormalities of Aβ42/40 and PTau217 are positively correlated with age and the proportion of B cells, and negatively correlated with cognitive domain scores for executive ability, attention, and language ability. CONCLUSION: Abnormalities in AD plasma biomarkers are associated with immune activation (particularly B cells and NK cells), aging, cardiovascular and gastrointestinal risk factors, and cognitive decline. The concurrent abnormalities of multiple biomarkers may exacerbate these associations, although some immune regulatory pathways do not show significant effects.