Background
Rheumatoid arthritis (RA) is an autoimmune disorder characterized by the inflammation-induced joint damage. Timely diagnosis and treatment are crucial to prevent lasting disability. Here, we aim to evaluate whether exosomal miRNAs could serve as promising biomarkers for expeditious RA diagnosis and effective therapy.
Methods
First, we performed small RNA sequencing to determine the miRNA profiles of serum exosomes within a screening cohort comprising 18 untreated active RA patients, along with 18 age and gender-matched healthy controls. Subsequently, the miRNA profiles were then validated in a training cohort consisting of 24 RA patients and 24 healthy controls, using RT-qPCR methodology. Finally, the selected exosomal miRNAs were subjected to validation in a larger cohort comprising 108 RA patients and 103 healthy controls. The diagnostic efficacy of the exosomal miRNAs was evaluated by receiver operating characteristic (ROC) curve analysis. The biological functions of the miRNAs were determined by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses.
Results
Our results first demonstrated a noteworthy upregulation of three specific miRNAs (miR-885-5p, miR-6894-3p, and miR-1268a) in the serum exosomes of patients of RA patients as compared with healthy controls. The combination of three miRNAs along with Anti-Cyclic Citrullinated Peptide Antibodies (ACPA) exhibited excellent diagnostic accuracy, yielding an area under the curve (AUC) of 0.963 (95% confidence interval = 0.941–0.984), a sensitivity of 87.96%, and a specificity of 93.20%. Notably, miR-885-5p exhibited remarkable discriminatory capacity by itself indistinguishing ACPA- negative RA patients from healthy controls, with an AUC of 0.993 (95% CI = 0.978-1), a sensitivity of 96.67%, and a specificity of 100%. Moreover, in the assessment of therapeutic effectiveness, the expression of miR-1268a displayed a significant reduction on the 29th day of MTX treatment in RA patients. This decline in expression paralleled the trends observed in TJC28 (28-joint tender count), SJC28 (28-joint swollen count), and DAS28-CRP (Disease Activity Score with 28-joint count using C-Reactive Protein), all of which are indicative of RA disease activity. Finally, predictive analysis indicated that all three exosomal miRNAs target pivotal signaling molecules involved in inflammatory pathways, thereby demonstrating effective modulation of the immune system.
Conclusions
In this study, we have successfully demonstrated the promising potential of serum exosomal miRNAs, particularly miR-885-5p, miR-6894-3p and miR-1268a, hold promising potential as biomarkers for the early diagnosis and prediction of RA for the first time. These findings highlight the importance of exosomal miRNAs in the realm of RA diagnosis and disease monitoring.
