Role of tumor necrosis factor-alpha, interleukin-8, and dexamethasone in the focal adhesion kinase expression by human nucleus pulposus cells.

Abstract

STUDY DESIGN: Human nucleus pulposus cells from intervertebral disc specimens were cultured to study the effects of tumor necrosis factor (TNF)-alpha and interleukin (IL)-8 on the focal adhesion kinase (FAK) expression by these cells. The effect of co-stimulation with dexamethasone on the FAK expression by nucleus pulposus cells was also studied.

OBJECTIVES: To evaluate the possible role of activated FAK expressed by the human nucleus pulposus cells and its correlation with inflammatory cytokines (TNF-alpha, IL-8) and dexamethasone.

SUMMARY OF BACKGROUND DATA: There have been no reported studies showing the correlation between the activated FAK expression by human nucleus pulposus cells with inflammatory cytokines and dexamethasone.

METHODS: The FAK expression in cultured human nucleus pulposus cells was studied, and Western blot and immunofluorescence analysis were performed to assess its relation to TNF-alpha, IL-8, and dexamethasone.

RESULTS: Treatments of TNF-alpha and IL-8 up-regulated the activated FAK expression. Dexamethasone attenuated the cytokine-induced FAK expression. The effects of inflammatory cytokines on the FAK expression were found to be concentration dependent, with greater correlation shown by IL-8 than TNF-alpha.

CONCLUSION: TNF-alpha and IL-8 stimulation up-regulated the FAK expression of human nucleus pulposus cells, and the coadministration of dexamethasone attenuated it.