Objective: Low-frequency vibration accelerates cartilage degeneration in knee osteoarthritis (KOA) rat model. In this article, we investigated whether whole-body vibration (WBV) increases cartilage degeneration by regulating tumor necrosis factor-α (TNF-α) in KOA.
Design: Proteomics analysis was used to filter candidate protein from synovial fluid (SF) in KOA people after WBV. Enzyme-linked immunosorbent assay (ELISA) was used to estimate changes in TNF-α levels in SF. The C57 mice and TNF-α knock-out mice were sacrificed for the KOA model and WBV intervention. The cartilage was tested by ELISA, histology, terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL), immunohistochemistry, and reverse transcriptase polymerase chain reaction. Luciferase activity test in vitro study was conducted to confirm the relationship between TNF-α and the candidate protein.
Results: Differentially expressed proteins were enriched in the glycolytic process, glucose catabolic, and regulation of interleukin-8 (IL-8) secretion processes. Phosphoglycerate kinase, triosephosphate isomerase 1, T cell immunoglobulin- and mucin-domain-containing molecules 2, fumarylacetoacetate hydrolase (FAH), and TNF were the hub node. TNF-α expression increased in SF after WBV (P < 0.05). The cartilage was more degenerated in the TNF-α-/- mice group compared to controls. A significant change was observed in collagen II and FAH (P < 0.05). TNF-α expression improved in C57 mice (P < 0.05). Apoptosis of chondrocytes was inhibited in TNF-α-/- mice by the TUNEL test. Luciferase activity significantly increased in TNF-α + FAH-Luc cells (P < 0.05).
Conclusion: A novel mechanism underlying WBV-triggered cartilage degeneration was found in KOA that demonstrated the critical regulatory function of TNF-α and FAH during WBV.
Keywords: cartilage; degeneration; knee; osteoarthritis; vibration.