Expression and distribution of interleukin-17 in degenerate human cervical intervertebral discs

Objective To investigate the expression and distribution of interleukin-17(IL-17)in degenerate human cervical intervertebral discs tissues,and to explore the relationship between IL-17 and cervical intervertebral disc degeneration.Methods IL-1β,IL-17,tumor necrosis factor(TNF-α) and retinoid-related orphan receptor(RORγτ)mRNA levels were respectively measured by real-time quantitative reverse transcription-polymerase chain reaction(QT-PCR)in 30 surgical degenerate cervical intervertebral discs tissues(degeneration group)and 10 nondegenerate control tissue(control group).And the level of IL-17 protein,CD4 cell surface antigen were measured by immunohistochemistry staining.Results The mean IL-1β,IL-17,TNF-α,RORγτ mRNA levels in degeneration group were significantly higher than that in control group(P0.001),and the expression of these factors in nucleus pulposus were significantly higher than that in annulus fibrosus in degeneration group(P0.05).The expression level of IL-17 mRNA was positively correlated with RORγτ mRNA level(R=0.61,P0.001).Immunoreactivity of IL-17 and CD4 cell surface antigen were significantly greater in degenerate discs than in controls(P0.001),and the immunoreactivity in nucleus pulposus was higher than that in annulus fibrosus in degeneration group(P0.05).Conclusion The expression level of IL-17 mRNA and IL-17 protein were significantly increased in degenerate human cervical discs tissues than that in autopsy control tissues,and the expression in nucleus pulposus was greater than in annulus fibrosus.These findings suggest involvement of IL-17 in the pathome chanism of intervertebral disc degeneration.Immune inflammation mediated by Th17 lymphocytes may play an important role in the development and progression of human cervical intervertebral disc degeneration.