Stress deprivation simultaneously induces over-expression of interleukin-1beta, tumor necrosis factor-alpha, and transforming growth factor-beta in fibroblasts and mechanical deterioration of the tissue in the patellar tendon

J Biomech. 2005 Apr;38(4):791-8. doi: 10.1016/j.jbiomech.2004.05.009.


To test the hypothesis that stress deprivation induces over-expression of cytokines in the patellar tendon, 40 rats were divided into the following two groups. In the stress-shielded group, we slackened the patellar tendon in the right knee by drawing the patella toward the tibial tubercle with flexible wires. In the control group, we performed a sham operation on the right knee. Animals were killed at 2 or 6 weeks for immunohistological evaluation and biomechanical examination. For IL-1beta, TNF-alpha and TGF-beta, the ratio of positively stained specimens to total specimens was significantly higher in the stress-shielded tendons than in the control tendons. The elastic modulus of the stress-shielded tendon was significantly lower than that of the control tendon, while the cross-sectional area of the stress-shielded tendon was significantly greater than that of the control tendon. Therefore, the present study indicated that stress shielding induced the over-expression of IL-1beta, TNF-alpha and TGF-beta in patellar tendon fibroblasts with mechanical deterioration of the tendon. Regarding clinical relevance, the present study suggests a possible application of an anti-IL-1beta or anti-TNF-alpha strategy for reducing the mechanical deterioration of tendons and ligaments in response to stress deprivation, although this study did not directly show that over-expression of IL-1beta or TNF-alpha in response to stress deprivation was the causation of mechanical deterioration of tendons.

MeSH terms

  • Animals
  • Biomechanical Phenomena
  • Cytokines / genetics*
  • Fibroblasts / metabolism
  • Fibroblasts / pathology*
  • Gene Expression Regulation / physiology*
  • Interleukin-1 / genetics
  • Male
  • Patella / physiology*
  • Rats
  • Rats, Wistar
  • Stress, Mechanical
  • Tendons / pathology*
  • Tendons / physiopathology
  • Transforming Growth Factor beta / genetics
  • Tumor Necrosis Factor-alpha / genetics


  • Cytokines
  • Interleukin-1
  • Transforming Growth Factor beta
  • Tumor Necrosis Factor-alpha