Characteristics of chemokines and pro‐inflammatory cytokines in elderly with major depressive disorder

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AbstractBackgroundResearch evidence has shown that late life depression (LLD) and amnestic mild cognitive impairment (aMCI) are both related to Alzheimer's disease (AD) and usually accompanied by inflammatory dysregulation, but few studies have compared the levels of chemokines and cytokines between these two disorders.MethodSixty‐nine study subjects were age‐ and gender‐matched outpatients with LLD or aMCI without dementia (based on DSM‐IV criteria) and normal controls (NC) in community. All individuals were administered Chinese versions of MoCA, Chinese version of neuropsychological test battery and Geriatric Depression Scale. Chemokines and pro‐inflammatory cytokines, including C‐X‐C chemokine ligand(CXCL5, CXCL6, CXCL8, CXCL9, CXCL11,CXCL16),C‐C chemokine ligand (CCL1,CCL7,CCL3, CCL8,CCL19,CCL20,CCL24,CCL11,CCL23,CCL27, CCL2, CCL13, CCL15, CCL17, CCL25), high sensitive C‐reactive protein (hsCRP), Interleukin 1‐beta (IL‐1β), macrophage inflammatory protein (MIP)‐2, Interferon‐γ‐inducing factor(IFN‐γ), vascular cell adhesion molecule‐1(VCAM‐1), interleukin‐2(IL‐2),interleukin‐4(IL‐4), tumor necrosis factor‐alpha (TNF‐α) and interleukin‐6 (IL‐6) were assessed in all subjects by Luminex assays.ResultElderly with major depressive disorder had less education, lower rate of having habits in taking regular exercise or drinking tea and even lower scores on cognitive tests than aMCI patients and healthy controls. LLD group showed higher level of IL‐6( P < 0.05 ) than the control or mild cognitive impairment subjects. However, They exhibited a significantly lower levels of CXCL5,CXCL6,CXCL16, and CCL5 (all p < 0.05) than the NC groups. Furthermore, The results also showed that LLD group had lower levels of CCL2,CCL17,CCL15,CXCL11 and CCL13 than the aMCI group. The multiple regression analysis showed that CCL25,CXCL6 was significantly related to cognitive scores in female.ConclusionWe are the first to report that LLD show different characteristics in inflammatory dysfunction from amnestic mild cognitive impairment patients and normal controls. Low levels of CCL2, CCL5,CCL13, CCL15,CCL17, CXCL5,CXCL6,CXCL11and CXCL16 were found in LLD than in aMCI. These results may suggest a quite different inflammatory dysregulation in LLD from aMCI though elderly with depression also show deficits in cognition. Future longitudinal studies should further explore the heterogeneity of LLD and whether these cytokines could be early markers to predict dementia.