Huang Le-Tian, Zhang Cheng-Pu, Wang Yi-Bing, Wang Jia-He
Department of Oncology, Shengjing Hospital of China Medical University, Shenyang, China.
Department of Family Medicine, Shengjing Hospital of China Medical University, Shenyang, China.
Front Aging Neurosci. 2022 May 6;14:888946. doi: 10.3389/fnagi.2022.888946. eCollection 2022.
Inflammation and immune dysfunction play significant roles in the pathogenesis of Alzheimer's disease (AD)-related dementia. Changes in peripheral blood cell profiles are a common manifestation of inflammation and immune dysfunction and have been reported in patients with AD or mild cognitive impairment (MCI). We systematically evaluated the association of peripheral blood cell counts and indices with AD or MCI through a meta-analysis.
We electronically searched sources to identify all case-control trials comparing peripheral blood cell counts and/or lymphocyte subsets between patients with AD or MCI and healthy controls (HCs). Meta-analyses were used to estimate the between-group standardized mean difference (SMD) and 95% confidence interval (CI).
A total of 36 studies involving 2,339 AD patients, 608 MCI patients, and 8,352 HCs were included. AD patients had significantly decreased lymphocyte counts (SMD -0.345, 95% CI [-0.545, -0.146], = 0.001) and significantly increased leukocyte counts (0.140 [0.039, 0.241], = 0.006), neutrophil counts (0.309 [0.185, 0.434], = 0.01), and neutrophil-lymphocyte ratio (NLR) (0.644 [0.310, 0.978], < 0.001) compared to HCs. Similarly, significantly increased leukocyte counts (0.392 [0.206, 0.579], < 0.001), NLR (0.579 [0.310, 0.847], < 0.001), and neutrophil counts (0.248 [0.121, 0.376], < 0.001) were found in MCI patients compared with HCs. A significantly decreased percentage of B lymphocytes (-1.511 [-2.775, -0.248], = 0.019) and CD8 T cells (-0.760 [-1.460, -0.061], = 0.033) and a significantly increased CD4/CD8 ratio (0.615 [0.074, 1.156], = 0.026) were observed in AD patients compared to HCs. Furthermore, significant changes in hemoglobin level and platelet distribution width were found in patients with AD or MCI compared with HCs. However, no significant difference was found between AD or MCI patients and HCs in terms of platelet counts, mean corpuscular volume, red cell distribution width, mean platelet volume, and CD4 T, CD3 T, or natural killer cell counts.
Changes in peripheral blood cell profiles, particularly involving leukocyte, lymphocyte, neutrophil, and CD8 T cell counts, as well as the NLR and the CD4/CD8 ratio, are closely associated with AD. The diagnostic relevance of these profiles should be investigated in future.
炎症和免疫功能障碍在阿尔茨海默病（AD）相关痴呆的发病机制中起重要作用。外周血细胞谱的变化是炎症和免疫功能障碍的常见表现，并且在AD或轻度认知障碍（MCI）患者中已有报道。我们通过荟萃分析系统评估了外周血细胞计数和指标与AD或MCI的关联。
我们通过电子检索资料，以确定所有比较AD或MCI患者与健康对照（HCs）外周血细胞计数和/或淋巴细胞亚群的病例对照试验。荟萃分析用于估计组间标准化均值差（SMD）和95%置信区间（CI）。
共纳入36项研究，涉及2339例AD患者、608例MCI患者和8352例HCs。与HCs相比，AD患者淋巴细胞计数显著降低（SMD -0.345，95%CI[-0.545，-0.146]，P = 0.001），白细胞计数显著升高（0.140[0.039，0.241]，P = 0.006）、中性粒细胞计数显著升高（0.309[0.185，0.434]，P = 0.01）以及中性粒细胞与淋巴细胞比值（NLR）显著升高（0.644[0.310，0.978]，P < 0.001）。同样，与HCs相比，MCI患者白细胞计数显著升高（0.392[0.206，0.579]，P < 0.001）、NLR显著升高（0.579[0.310，0.847]，P < 0.001）以及中性粒细胞计数显著升高（0.248[0.121，0.376]，P < 0.001）。与HCs相比，AD患者B淋巴细胞百分比显著降低（-1.511[-2.775，-0.248]，P = 0.019）和CD8 T细胞百分比显著降低（-0.760[-1.460，-0.061]，P = 0.
