Diagnostic: miR-146a expression before treatment is inversely correlated with HAM-D score Therapeutic: miR-146a mimic treatment inhibited TNF-α, IL-1β, IRAK1 and TRAF6 expression in BV-2 cells Predictive: miR-146a may be a promising marker to predict fluoroxetine and antidepressant response in patients with MDD. This evidence concerns the gene IRAK1 and major depressive disorder.