Chemokines in bipolar disorder: trait or state?

Recent evidence has suggested that inflammatory and immune mechanisms may play a role in the pathophysiology of bipolar disorder (BD). Only a few studies have assessed the profile of chemokines, a family of chemotactic cytokines related to the recruitment of leukocytes, in BD. The objective of our study was to evaluate the plasma levels of chemokines in BD patients in different mood states in comparison with healthy controls. Seventy BD type I patients (35 in euthymia and 35 in mania), and 50 healthy controls matched by age, gender, and education level were enrolled in this study. All subjects were assessed by the Mini-International Neuropsychiatry Interview and the patients by the Young Mania Rating Scale and the Hamilton Depression Rating Scale. The plasma levels of CCL2, CCL3, CCL11, CCL24, CXCL8, and CXCL10 were measured by enzyme-linked immunosorbent assay. BD patients presented higher plasma levels of CCL11 (1.69-fold increase; p < 0.001), CCL24 (1.40-fold increase; p = 0.02), CXCL10 (1.45-fold increase; p < 0.001) and decreased plasma levels of CXCL8 (8.68-fold decrease p < 0.001). Logistic regression stressed the main effect of increased plasma levels of CXCL10 (OR = 1.009, 95 % CI = 1.000-1.018, p = 0.042) and CCL11 (OR = 1.002, 95 % CI = 1.001-1.003, p = 0.003) and decreased plasma levels of CXCL8 (OR = 0.995, 95 % CI = 0.990-0.999, p = 0.013) to BD. This study reinforces the view that BD is associated with an immune dysfunction.