Transcriptomic profiling as biological markers of depression– a pilot study in unipolar and bipolar women

A significant challenge in psychiatry is the differential diagnosis of depressive episodes in the course of mood disorders. Gene expression profiling may provide an opportunity for such distinguishment. We studied differentially expressed genes in women with a depressive episode in the course of unipolar depression (UD) (n = 24) and bipolar disorder types I (BDI) (n = 13) and II (BDII) (n = 19), and healthy controls (n = 15). Different types of depression varied in the number and type of up or down-regulated genes. The pathway analysis showed: in UD, up-regulated rheumatoid arthritis pathway (including <i>ITGB2, CXCL8, TEK, TLR4</i> genes), and down-regulated taste transduction pathway (<i>TAS2R10, TAS2R46, TAS2R14, TAS2R43, TAS2R45, TAS2R19, TAS2R13, TAS2R20, GNG13</i>); in BDI, eight down-regulated pathways: glutamatergic synapse, retrograde endocannabinoid signaling, axon guidance, calcium signaling, nicotine addiction, PI3K-Akt signaling, drug metabolism - cytochrome P450, and morphine addiction; in BDII, up-regulated osteoclast differentiation and Notch signaling pathway, and down-regulated type I diabetes mellitus pathway. Distinct expression markers analysis uncovered the unique for UD, up-regulated bladder cancer pathway (<i>HBEGF</i> and <i>CXCL8 genes</i>). This pilot study suggests a probability of differentiating depression in the course of UD, BDI, and II, based on transcriptomic profiling.