Abstract
OBJECTIVE: Psoriatic arthritis (PsA) is a chronic immune-mediated inflammatory arthritis that develops in 30% of patients with psoriasis, leading to increased morbidity and mortality and reduced quality of life. MicroRNAs (miRNAs) modulate gene expression and have been associated with the pathogenesis of immune-mediated disorders. We aimed to identify miRNAs that can be used as biomarkers for the development of PsA in patients with psoriasis. METHODS: miRNA expression levels were assessed in serum samples from 28 patients with PsA, 35 patients with cutaneous psoriasis without arthritis (PsC), and 28 healthy controls through next-generation sequencing. Differential expression was assessed by linear modeling with empirical Bayes moderation corrected for sequencing batch, age, sex, and duration of psoriasis. For validation, we measured the expression of >191 genes predicted to be targeted by the dysregulated miRNAs using a custom NanoString probe panel in an independent cohort of 144 patients with PsA and 88 patients with PsC. The enrichment of specific pathways corresponding to the differentially expressed gene targets was examined using pathDIP. RESULTS: In the discovery cohort, the miRNA miR-190a-5p was significantly down-regulated in patients with PsA compared to those with PsC (P< 0.05), and both miR-190a-5p and miR-26b-5p were down-regulated in patients with PsA versus healthy controls (P < 0.05). In the validation cohort, 26 gene targets of both of these miRNAs were differentially expressed. These genes were enriched in signaling pathways associated with bone formation and regeneration: Wnt and transforming growth factor β. CONCLUSION: Serum expression levels of miR-190a-5p and miR-26b-5p can potentially serve as biomarkers for PsA development.