The correlation between brain functional network connectivity and inflammatory cytokines in patients with bipolar disorder II depressive episodes / 中华行为医学与脑科学杂志

ABSTRACT

Objective:To investigate the functional connectivity of default mode network (DMN) and limbic system, the expression level of inflammatory cytokine and their correlation in bipolar disorder type Ⅱ(BDⅡ) patients with depressive episodes.Methods:Thirty-three BD Ⅱ patients with depressive episodes and forty-six healthy controls were recruited to complete the resting-state functional magnetic resonance imaging (rs-fMRI). After image preprocessing, the DMN and limbic system were extracted from the image data by independent component analysis (ICA), so as to compare the differences of functional connectivity of resting brain network between the patients and the controls.Serum levels of inflammatory cytokines interleukin-6 (IL-6), interleukin-8(IL-8), interleukin-10(IL-10), tumor necrosis factor-α (TNF-α), and C-C motif chemokine ligand 4 (CCL4) in patients and healthy controls were detected.The correlation between functional connectivity of different brain regions and inflammatory cytokines was analyzed.SPSS 17.0 software was used for data statistical analysis.The two samples were compared using t-test or Mann-Whitney U-test, and Spearman was used for correlation testing. Results:In BDⅡ patients, the functional connectivity of the right medial prefrontal cortex(cluster-size=7 voxel, cluster-level PGRF<0.05, MNI x=6, y=54, z=9, t=-3.765) and the left superior frontal gyrus(cluster-size=10 voxel, cluster-level PGRF<0.05, MNI x=-21, y=54, z=15, t=-4.139) in DMN decreased, while the left cerebellum Ⅳ and Ⅴ lobules of limbic system (cluster-size=21 voxel, cluster-level PGRF<0.05, MNI x=-15, y=-24, z=-30, t=4.468) and cerebellar tonsil of left cerebellum posterior lobe(cluster-size=8 voxel, cluster-level PGRF<0.05, MNI x=-15, y=-51, z=-45, t=4.138) in the limbic system increased.Compared with the healthy controls, the serum levels of IL-10(7.39 (6.33, 9.32) pg/mL vs 6.54 (5.84, 7.39) pg/mL, Z=-2.937, P=0.003)and CCL4 (39.31 (25.77, 68.70) pg/mL vs 31.30 (20.32, 40.89) pg/mL, Z=-2.209, P=0.027) were higher in BDⅡ patients.The functional connectivity of the left cerebellum Ⅳ and Ⅴ lobules was positively correlated with the serum levels of IL-10 ( r=0.432, P=0.031) and that of the cerebellar tonsil of left cerebellum posterior lobe was positively correlated with the serum levels of IL-10 ( r=0.429, P=0.032) and CCL4 ( r=0.402, P=0.046). Conclusion:The functional connectivity of DMN and limbic system in BDⅡ patients with depressive episode is abnormal in resting-state fMRI.The expression level of inflammatory cytokines in patients' serum increases, and has correlation with the functional connection of limbic system.