A recent meta-analysis of 82 studies including 3212 MDD patients and 2798 healthy controls revealed increased levels of IL-6, TNF, IL- 10, sIL-2, C-C motif chemokine ligand 2 (CCL)2, IL-13, IL-18, IL-12, IL-1RA, and soluble TNF receptor (sTNFR) in MDD patients [29]. Here, IL18 is linked to major depressive disorder.