IL6 and depressive symptom measurement: The levels of several inflammatory markers, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), are significantly increased in patients with depression compared to these in normal subjects [9], while administration of IL-1 receptor antagonist (IL-1ra) ameliorated depressive-like behaviors [10].