Tnfa, Il6, Cxcl1, and Adam8 Genes Are the Early Markers After Mouse Tail Intervertebral Disc Injury.

Objectives: The early molecular events after intervertebral disc injury remain unclear. In this study, we aimed to compare inflammatory markers from 1 day to 4 wks after injury to have a comprehensive understanding of the intervertebral disc response to injury. Design:Mouse tail intervertebral disc injury was induced by a needle puncture. Inflammatory marker gene expression and morphological changes were recorded at 1 day, 1 wk, and 4 wks after injury. Results: Tnfa, Il6, and Cxcl1 gene expression peaked at day 1 post-needle puncture of the mouse intervertebral disc, Adam8 gene expression peaked at 1-wk time point, while Tipe2 gene expression was upregulated at week 4 postinjury. F4/80 positive cells, likely to be macrophages, are present as early as day 1 in the injured intervertebral discs and consistently present at week 4 post-injury. Loss of Safranin O staining and increased histological scores of the injured intervertebral discs are consistent with progressive degeneration after injury. Conclusions: Inflammatory cytokines including Tnfa precede Tipe2, suggesting that Tipe2 is likely induced by Tnfa. Upregulation of Adam8 and Cxcl1 gene expression persisted at week 4, suggesting that they play a role in the transition to chronic phase of intervertebral disc degeneration. [ABSTRACT FROM AUTHOR]