Role of IL-17 in nucleus pulposus cell proliferation and metabolism culturedin vitro

ABSTRACT

Objective:To explore the role of cytokine, interleukin-17(IL-17) in human degenerative disc disease.Methods:Through magnetic resonance imaging, human degenerative disc tissues were confirmed from the isolated nucleus pulposus cells, which were then cultured in vitro.The cells were cultured with and without different concentrations ofIL-17.2 ng/mL,5 ng/mL,10 ng/mL,15 ng/mL and20 ng/mLIL-17 concentrations were used for stimulation.After72 hours, the inhibition rate of proliferation was measured byMTS method.For48 and96 hours, the nucleus pulposus cells were cultured with and without the appropriateIL-17 concentrations.The mRNA and protein expression levels of the matrix macromolecules and degrading tissue genes were measured byReal-timePCR andWestern blot analysis.Results:It was noted that nucleus pulposus cell proliferation was inhibited after culturing in vitro withIL-17 stimulation, and it was further observed that the inhibition effect was significantly stronger with15 ng/mLIL-17 concentration.With the dosage of15 ng/mL,IL-17 stimulation induced multiple cellular responses, such as the significant increase in mRNA expression for both aggrecan(ACAN) and type Ⅰ collagen(COL1A1) genes(P<0.05), and the significant decrease in mRNA expression of both degrading tissue genes,MMP3 andTIMP3(P<0.05).Western blot results also showed that the protein level ofCOL1A1 was significantly decreased(t=3.199,P=0.006), while the protein level of one peptidases(ADAMTS5) significantly increased(t=2.667, P=0.021).Conclusions:These findings suggest thatIL-17 can inhibit proliferation and affect the metabolism of the cultured nucleus pulposus cells in vitro, and these findings could possibly contribute to the degenerative changes that occur inDDD through extracellular matrix synthesis inhibition, promoting nucleus pulposus extracellular matrix degradation and disrupting the metabolic balance.