A preliminary analysis of association between plasma microRNA expression alteration and symptomatology improvement in Major Depressive Disorder (MDD) patients before and after antidepressant treatment

Background and Objectives: Currently, there is a serious need to find practical biomarker(s) for Major Depressive Disorder (MDD) therapeutic target(s). This study aimed to investigate the association between microRNA (miRNA, miR) expression level in Peripheral Blood Mononuclear Cells (PBMCs) and symptomatology improvement in MDD patients before and after six-week antidepressant treatment. Methods: By using an Affymetrix array that covers 723 human miRNAs, 26 miRNAs were identified with significantly altered expression in PBMCs in MDD patients, of which 10 miRNAs were selected for quantitative real-time Reverse Transcription Polymerase Chain Reaction (RT-PCR) study. Twenty out of all the 81 MDD patients were selected for miRNA expression levels testing and symptomatology assessments before and after six-week treatment. Results: Compared with the control group, the expression levels of miR-26b, miR-4743, miR-4498, miR-4485 and miR-1972 of the MDD group were significantly higher (P < 0.05); the changes of expression levels of miR-4743, miR-4498, miR-4485 and miR-1972 were positively related to retardation improvement (P < 0.05), and the change of expression level of miR-26b negatively to the improvement of day and night change (P < 0.05); regression analysis result demonstrated that the alteration of miR-4485 expression accounted for 28.8% of retardation improvement (P < 0.05). Conclusions: These five miRNAs (miR-4743, miR-4498, miR-4485, miR-1972 and miR-26b) may serve as biomarker for MDD diagnosis and therapeutic targets for MDD treatment.