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.

Purpose: The serotonin system and parenting styles have been reported to be involved in the pathogenesis of anorexia nervosa (AN). The study was aimed to explore the effect of the methylation of the promoter region of serotonin transporter gene (SLC6A4), also called 5-HTTLPR, parenting styles as well as their interaction on AN.Methods: 91 AN patients (ANs) and 87 healthy controls (HCs) were recruited, from whom 41 ANs and 40 HCs completed the environmental assessment. 5-HTTLPR methylation levels, clinical symptoms and environmental factors were assessed at baseline for all participants. 5-HTTLPR methylation was measured by MassArray methods and clinical symptoms were mainly evaluated by the EDE-Q6.0 scale. Environmental assessment is the parenting attitudes and behaviors used by the EMBU scale.Results: ANs had higher methylation at CpG 11, CpG 24.25, CpG 31.32 and CpG_mean than HCs (P=0.039, 0.042, 0.018, 0.001). Furthermore, it was the binge/purging subtype that revealed significant hypermethylation at CpG 24.25 and CpG_mean (P=0.027, 0.031). Both CpG11 methylation level and the parenting styles of refusal denial, overprotection for father were both positively correlated the EDEQ-6.0 scores in ANs (P=0.047, 0.018). Besides, their interaction analysis found, it was the overprotection, not the refusal denial for father that significantly associated with EDEQ-6.0 scores in ANs (P=0.030).Conclusions: Our study provided preliminary evidence that 5-HTTLPR DNA methylation at CpG11 and parenting styles of refusal denial, overprotection for father played vital roles in AN pathogenesis. Their interaction analysis indicated it was father’s overprotection that significantly associated with the clinical symptoms in ANs.