The primary objective of this analysis is to evaluate associations between levels of pro-inflammatory markers; specifically IL-6, CRP, and TNFα, and the anti-inflammatory cytokine IL-10, with a therapeutic response to metyrapone or placebo augmentation of serotonergic antidepressant medication in TRD patients in order to explore whether these inflammatory proteins influenced the extent of symptom change. This evidence concerns the gene IL6 and treatment resistant depression.