Nintedanib ameliorates osteoarthritis in mice by inhibiting synovial inflammation and fibrosis caused by M1 polarization of synovial macrophages via the MAPK/PI3K‐AKT pathway

• Published in: The FASEB journal 2023-10, Vol.37 (10), p.e23177-n/a
• Main Authors: Yan, Jiangbo, Feng, Gangning, Yang, Yong, Zhao, Xin, Ma, Long, Guo, Haohui, Chen, Xiaolei, Wang, Hui, Chen, Zhirong, Jin, Qunhua
• Format: Article
• Language: English
• Subjects: M1 polarization; macrophage; MAPK; nintedanib; osteoarthritis; PI3K‐AKT; synovial
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fj.202300944RR

Synovial inflammation and fibrosis are important pathological changes associated with osteoarthritis (OA). Herein, we investigated if nintedanib, a drug specific for pulmonary fibrosis, plays a positive role in osteoarthritic synovial inflammation and fibrosis. We assessed the effect of nintedanib on osteoarthritic synovial inflammation and fibrosis in a mouse model of OA created by destabilization of the medial meniscus and a macrophage M1 polarization model created by stimulating RAW264.7 cells with lipopolysaccharide. Histological staining showed that daily gavage administration of nintedanib significantly alleviated articular cartilage degeneration, reduced the OARSI score, upregulated matrix metalloproteinase‐13 and downregulated collagen II expression, and significantly reduced the synovial score and synovial fibrosis in a mouse OA model. In addition, immunofluorescence staining showed that nintedanib significantly decreased the number of M1 macrophages in the synovium of a mouse model of OA. In vitro results showed that nintedanib downregulated the phosphorylation levels of ERK, JNK, p38, PI3K, and AKT while inhibiting the expression of macrophage M1 polarization marker proteins (CD86, CD80, and iNOS). In conclusion, this study suggests that nintedanib is a potential candidate for OA treatment. The mechanisms of action of nintedanib include the inhibition of M1 polarization in OA synovial macrophages via the MAPK/PI3K‐AKT pathway, inhibition of synovial inflammation and fibrosis, and reduction of articular cartilage degeneration. Synovial inflammation and fibrosis resulting from M1 polarization of synovial macrophages is an important pathology in OA mice models. Nintedanib inhibited M1 polarization in macrophages stimulated by LPS. The primary mechanism involves the MAPK and PI3K‐AKT pathways whereby nintedanib inhibits M1 polarization by inhibiting phosphorylation of ERK, JNK, p38, PI3K, and AKT in the MAPK and PI3K‐AKT pathways in macrophages, and alleviates synovial inflammation and fibrosis caused by M1 polarization in macrophages.