Objective: The aim of this study was to investigate the microRNA (miRNA) expression pattern in synovial fluid from patients with knee osteoarthritis (OA) after treatment with intra-articular injection of hyaluronan (HA).
Methods: Twelve OA patients were enrolled in accordance with the Kellgren-Lawrence classification of knee OA. All patients received intra-articular injection of HA once a week for 5 weeks and were evaluated with the Western Ontario and McMaster Universities (WOMAC) index at baseline. TaqMan miRNA assay profiling was performed on synovial fluid RNAs extracted from OA patients pre-injection and after 5 weeks of treatment with HA. Validation was performed using independent samples, including ten healthy controls and ten matched OA patients.
Results: Forty-three miRNAs (21 overexpressed miRNAs and 22 underexpressed miRNAs) were differentially expressed in OA patients before and after treatment with HA (P < 0.05, false discovery rate corrected). Further bioinformatics prediction by mirPath indicated that the differential miRNA signatures in synovial fluid extracted from the OA patients demonstrated primarily upregulation of the PI3K-Akt signaling pathway, mitogen-activated protein kinase signaling pathway, regulation of autophagy, mRNA surveillance pathway, and B cell receptor signaling pathway. In addition, TaqMan real-time reverse transcription polymerase chain reaction was performed for validation on miR-146a, miR-155, let-7a, miR-181a, miR-454, and let-7b, which were significantly changed in abundance, using an independent cohort of ten healthy controls and ten OA patients as compared with those with intra-articular injection of HA.
Conclusion: Our results demonstrated that dysregulation in miRNAs in synovial fluid from OA patients and their affected biologic cellular processes might play important role in OA pathogenesis and HA-mediated therapeutics.