A double-blind, placebo-controlled, randomized clinical study demonstrated that treatment with TNF-α antagonist infliximab reduces depressive symptoms in treatment-resistant MDD patients having baseline high-sensitivity CRP (hs-CRP) concentration greater than 5 mg/L but not in patients with lower baseline hs-CRP, suggesting the potential of using immune-modulators to treat depressive symptoms in certain subgroup of MDD patients [9]. Here, TNF is linked to major depressive disorder.