Differential expression of circular RNAs in plasma exosomes from patients with ankylosing spondylitis

Exosomes are being extensively studied as a source of valuable new biomarkers. The underlying mechanism of ankylosing spondylitis (AS) may include changes in the circular RNAs (circRNAs) of exosomes. However, there is a lack of reports on the role of exosomal cirRNAs in the plasma of patients with AS. We isolated exosomes from the plasma of patients with AS and healthy individuals (controls). Subsequently, we investigated the circRNA profiles of the exosomes via high‐throughput RNA sequencing and identified 56 differentially expressed circRNAs in the exosomes of patients with AS compared with those of the healthy controls. Gene Ontology demonstrated that the differentially expressed circRNAs were mainly involved in the negative regulation of the activity of the transcription factor nuclear factor‐κB and bone remodelling that is potentially related to AS. Kyoto Encyclopedia Genes and Genome demonstrated that the most highly AS‐correlated pathways that were identified were ‘notch signalling pathway’ and those primarily involved with ‘cholinergic synapse’. Finally, we validated five differentially expressed circRNAs using quantitative real‐time polymerase chain reaction and predicted their potential functions through the circRNA–miRNA–mRNA network. Our study is the first to report changes in exosomal circRNAs from plasma samples of patients with AS, and provide novel targets for further investigation of molecular mechanisms and potential intervention therapy targets of AS.