Low-intensity pulsed ultrasound inhibits fibroblast-like synoviocyte proliferation and reduces synovial fibrosis by regulating Wnt/β-catenin signaling

• Main Authors: Bo Liao, Mengtong Guan, Qiaoyan Tan, Gailan Wang, Ruobin Zhang, Junlan Huang, Mi Liu, Hong Chen, Kaiting Li, Dingqun Bai, Ying Zhu
• Format: Article
• Language: English
• Published: Elsevier 2021-09-01
• Series: Journal of Orthopaedic Translation
• Subjects: Cell proliferation; Fibroblast-like synoviocyte; Low-intensity pulsed ultrasound; Osteoarthritis; Synovial fibrosis; Wnt/β-catenin signaling
• Online Access: http://www.sciencedirect.com/science/article/pii/S2214031X21000644

Objective: Synovial fibrosis is a characteristic symptom of osteoarthritis (OA), which is closely associated with joint pain and stiffness. Previous studies have reported that low-intensity pulsed ultrasound (LIPUS) can alleviate cartilage degradation in OA. However, the functions and mechanisms of LIPUS in OA synovial fibrosis are still unknown. Methods: The destabilization of the medial meniscus (DMM) mouse model of OA was established in C57 male mice and fibroblast-like synoviocytes (FLS) were isolated from synovial tissue of OA patients. The knee joint diameter, Masson's trichrome (MT) and Hematoxylin-eosin (HE) staining were used to evaluate synovial fibrosis and hyperplasia. The Immunohistochemistry (IHC) staining was performed to detected the expression of synovial fibrosis makers and the activation of Wnt/β-catenin signaling in vivo. FLS were treated with TGF-β1 to serve as an in vitro model of synovial fibrosis, Wnt3a was used to activate the Wnt/β-catenin signaling in cells. Cell proliferation was detected by using EdU assay, cell viability was performed by CCK8 assay. The protein levels of α-SMA, CTGF, Col Ⅰ, β-catenin, active β-catenin, c-Myc and cyclin D1 were examined by western blot and immunofluorescence staining. Results: Two weeks after the LIPUS treatment, the synovial fibrosis, synovial hyperplasia and synoviocyte proliferation in the DMM model were significantly decreased. In vitro, LIPUS directly inhibited the TGF-β1-induced fibrotic response and proliferation of FLS. Meanwhile, LIPUS suppressed Wnt/β-catenin signaling in the synovium of DMM mice and cultured FLS. More importantly, we found that the synovial fibrosis makers, Wnt/β-catenin pathway downstream proteins and FLS proliferation were significantly decreased in Wnt3a-stimulated FLS following LIPUS treatment. Conclusions: Our results present a novel role of LIPUS in OA-related synovial fibrosis, which is associated with its ability to repress Wnt/β-catenin signaling in FLS. The translational potential of this article: This study provides new insight into the clinical application of LIPUS as a therapeutic option to manage synovial fibrosis in OA.