GSE176223
Identification of synovial fibroblasts subsets associated with pain and progression of knee osteoarthritis
Background: Synovial inflammation is associated with pain severity in patients with knee osteoarthritis (OA). The aim here was to determine in a population with knee OA, whether synovial tissue from areas associated with pain exhibited different synovial fibroblast transcriptomes, compared to synovial tissue from sites not associated with pain. A further aim was to compare differences between early and end-stage disease synovial fibroblasts. Methods: Patients with early knee OA (n=29) and end-stage knee OA (n=22) were recruited. Patient reported pain was recorded by questionnaire and using an anatomical knee pain map. Proton density fat suppressed MRI axial and sagittal sequences were analysed and scored for synovitis. Synovial tissue was obtained from the medial and lateral parapatellar and suprapatellar sites. RNA sequencing was performed using Illumina's NextSeq 500 and analysed with Galaxy web platform, usegalaxy.org, and Qlucore software. Transcriptomes were functionally characterised using Ingenuity Pathway Analysis. Findings: Parapatellar synovitis was significantly associated with increased OA pain perception. Functional pathway analysis revealed that early OA painful sites mediate immune cell recruitment and promote the formation and development of neurites. Conclusion: OA disease progression and the presence of pain in early OA is associated with different synovial pathotypes. Further interrogation of these pathotypes will increase our understanding of the role of synovitis in OA joint pain and provide a rationale for the therapeutic targeting to alleviate pain in patients. Overall design: Transcriptomic profiling of early and end-stage knee OA synovium tissue from painful and non-painful sites.