CRP and major depressive disorder: 140 MDD patients with IMD characteristics (MDD with Inventory of Depressive Symptomatology (IDS) ≥ 26, IDS atypical, energy related symptoms ≥6, C-Reactive Protein (CRP) > 1 mg/L) will receive either 400 mg celecoxib per day or matching placebo for a period of 12 weeks.