For example, patients with MDD tend to present important changes in circulating monocytes, being characterized by presenting a pro-inflammatory status, accompanied by an increased expression of IL-1β and IL-6, and an increase in serum levels of TNF-α, IL-1β, and intestinal permeability markers like LPS-binding protein (LBP) and intestinal fatty acid-binding protein [62]. This evidence concerns the gene TNF and major depressive disorder.