Low-Frequency Vibration Promotes Tumor Necrosis Factor-α Production to Increase Cartilage Degeneration in Knee Osteoarthritis

Abstract

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.

Figure 1.

Isobaric tags for relative and absolute quantitation (iTRAQ) proteomic analysis and protein-protein interactions (PPI).

Figure 2.

Representative results of WBV treatment in vivo. (A) Red O-solid green stains the cartilage matrix of 4 groups. (B) Apoptosis stained of 4 groups by TUNEL. (C) Western blot of 4 groups. WBV = whole-body vibration; TNF-α = tumor necrosis factor-α; DMM = destabilization medial meniscus; α-SMA = α-smooth muscle actin.

Figure 3.

Expression of FAH, TIM2, and CRP in the cartilage in 4 groups. Expression of FAH, TIM2, and CRP in the cartilage was detected in different groups. FAH = fumarylacetoacetase hydrolase; TIM2 = tissue inhibitor of metalloproteinases 2; CRP = C-reactive protein; WBV = whole-body vibration; TNF-α = tumor necrosis factor-α; DMM = destabilization medial meniscus.

Figure 4.

TNF-α upregulates inflammation or apoptosis through FAH. (A) 293T cells were transfected with FAH-Luc and renila, with or without TNF-α; 48 hours after transfection, cells was performed luciferase assay. The luciferase activity was normalized to Renilla control, and expressed as fold increase (mean ± SD). Experiments were performed 2 times in triplicate. (B and C) SW1353 were co-transfected with TNF-α and FAH or FAH-siRNA; 48 hours after transfection, cells were harvested for immunoblot analysis with indicated antibodies. FAH = fumarylacetoacetase hydrolase; TNF-α = tumor necrosis factor-α.