To observe the baseline peripheral blood biomarkers in young adult individuals in the MDD or age-matched normal healthy (HC) groups, we first measured the levels of inflammatory-mediated markers (IL-1β, IL-6, CRP, IL-17, TNF-α, CCL1, CCL2, and adiponectin) and cortisol using the ELISA system. This evidence concerns the gene CCL2 and major depressive disorder.