Abstract
Background: Although increasing evidence implicates circular RNAs (circRNAs) in the pathogenesis of various autoimmune diseases, the potential role of circRNAs in rheumatoid arthritis (RA) remains poorly understood. Methods: Utilizing a two-phase study design, we performed high-throughput RNA sequencing on peripheral blood mononuclear cells (PBMCs) from three treatment-naïve RA patients and three healthy controls (HCs), followed by validation in an independent cohort of 32 RA patients and 32 HCs using real-time quantitative polymerase chain reaction (RT-qPCR). Results: A total of 157 circRNAs were differentially expressed between RA patients and HCs, including 91 upregulated and 66 downregulated circRNAs. Six circRNAs, including hsa_circ_0001394, hsa_circ_0001998, hsa_circ_0009172, hsa_circ_0006732, circRNA2842, and circRNA8330, were further confirmed to be upregulated in RA. Among them, hsa_circ_0001394 demonstrated perfect sensitivity (100%), and hsa_circ_0001998 exhibited perfect specificity (100%) in distinguishing RA from HCs. All six circRNAs showed considerable diagnostic performance, with area under the curve (AUC) values ranging from 0.794 to 0.993. Additionally, specific circRNAs correlated significantly with established serological markers: hsa_circ_0009172 expression was negatively associated with anti-cyclic citrullinated peptide (anti-CCP) antibody titers, whereas hsa_circ_0001998 expression correlated positively with rheumatoid factor (RF). Pathway enrichment analysis suggested that these differentially expressed circRNAs may participate in RA pathogenesis through key pathways like Wnt, calcium and VEGF signaling. Conclusion: Our study identifies several novel circRNAs with high diagnostic utility for RA, highlighting their potential as promising biomarkers and therapeutic targets.