Proteomic Analysis Reveals sympathetic system and immune-inflammation biomarkers in serum of drug-free obsessive-compulsive disorder

Abstract Obsessive-compulsive disorder (OCD) is a debilitating mental disorder, of which the mechanism is unclear. Biomarker detection will help in the mechanism exploration, early diagnosis and targeted treatment. Therefore, we conducted an iTRAQ-based proteomic analysis to compare serum proteome profile between OCD patients and healthy control, in order to find out the possible biomarkers of OCD and their underlying mechanisms. 81 drug-free OCD patients and 78 healthy controls were enrolled. A total of 479 proteins were identified and only those with a fold change ≥ 1.2 and p value༜0.05 were accepted as differentially expressed proteins (DEPs). 7 up-regulated proteins, and 28 down-regulated ones were discovered. Besides dopamine beta-hydroxylase that plays a part in sympathetic system, lots of other DEPs are involved in immuno-inflammatory process. These DEPs were enriched in 44 gene ontology (GO) terms. However, none of KEGG pathway was detected significantly enriched. Our study suggested these sympathetic system and immuno-inflammation related proteins as potential biomarkers of OCD. Especially, immuno-inflammation may play an important role in OCD pathophysiology. Further researches employing larger sample sizes, longitudinal design and multi-omics methodology will be needed to verify our results and clarify the role of DEPs in OCD.