Transforming growth factor-[beta] stimulates nerve growth factor production in osteoarthritic synovium

• Published in: BMC musculoskeletal disorders Vol. 20; no. 1
• Main Authors: Takano, Shotaro, Uchida, Kentaro, Itakura, Makoto, Iwase, Dai, Aikawa, Jun, Inoue, Gen, Mukai, Manabu, Miyagi, Masayuki, Murata, Kosuke, Sekiguchi, Hiroyuki, Takaso, Masashi
• Format: Journal Article
• Language: English
• Published: BioMed Central Ltd 10.05.2019
• Subjects: Analysis; Arthroplasty; Bone morphogenetic proteins; Care and treatment; Diagnosis; Diagnostic imaging; Enzyme-linked immunosorbent assay; Enzymes; Immunohistochemistry; Joint replacement; Knee replacement arthroplasty; Medical law; Medical research; Messenger RNA; Nerve growth factor; Orthopedic surgery; Osteoarthritis; Polymerase chain reaction; Radiography; RNA; Transforming growth factors
• ISSN: 1471-2474; 1471-2474
• DOI: 10.1186/s12891-019-2595-z

Background Nerve growth factor (NGF) contributes to pain in knee osteoarthritis (KOA) patients. Transforming growth factor-beta (TGF-[beta]) stimulates NGF expression in chondrocytes from KOA patients. However, the correlation between synovial TGF-[beta] and NGF levels has not been sufficiently studied in human KOA patients. Further, the mechanism governing NGF regulation by TGF-[beta] in synovial cells is unclear. Methods During total knee arthroplasty, we extracted the synovial tissue (SYT) of 107 subjects with unilateral Kellgren/Lawrence grade 3-4 KOA confirmed by radiography. We examined the distribution of TGF-[beta] and NGF using immunohistochemistry, and analyzed the relationship between NGF and TGFB mRNA levels. Cultured synovial cells extracted from SYT were exposed to culture medium (control), human recombinant TGF-[beta] (rhTGF-[beta]), rhTGF-[beta] + ALK5 inhibitor SB505124, rhTGF-[beta] + transforming growth factor activating kinase 1 (TAK1) inhibitor (5Z)-7-oxozeaenol, or rhTGF-[beta] + p38 inhibitor SB203580 for 30 min, 6 h and 24 h. NGF mRNA expressed by the cultured cells and NGF protein levels in the cell supernatant were detected by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Phosphorylation of p38 was evaluated by western blotting. Results NGF mRNA levels were positively correlated with those of TGFB. Cells expressing TGF-[beta] and NGF protein were observed in the lining layer of SYT. TGF-[beta] stimulated increased NGF mRNA expression and NGF protein production. The ALK5 inhibitor completely suppressed the TGF-[beta]-mediated increase in NGF expression and NGF production in synovial cells. ALK5, TAK1 and p38 inhibitors inhibited the TGF-[beta]-induced phosphorylation of p38, and TAK1 and p38 inhibitors partially inhibited the TGF-[beta]-mediated increase in NGF expression and NGF production in synovial cells. Conclusion TGF-[beta] regulates NGF production via the TGF-[beta]/ALK5 signaling pathway in osteoarthritic synovium. This effect may partially occur through inhibition of the TAK1/p38 pathway in the SYT of KOA patients. Keywords: Transforming growth factor-[beta], Nerve growth factor, Osteoarthritis, Synovium