P14ARF inhibits regional inflammation and vascularization in intervertebral disc degeneration by upregulating TIMP3.

In this study, we identified P14 alternate reading frame (P14ARF) as a novel regulator of inflammation and vascularization in intervertebral disk degeneration (IVDD). We collected IVD tissues from IVDD patients and normal individuals for analysis of P14ARF expression. We also induced experimental IVDD by needle puncture injuries in the caudal intervertebral disks of Sprague- Dawley (SD) rats and achieved recombinant adenovirus-mediated P14ARF overexpression in experimental IVDD rats. Regulation relationships between P14ARF and tissue inhibitors of metalloproteinases- 3 (TIMP3) were confirmed in P14ARF-overexpressed and TIMP3-depleted nucleus pulposus (NP) cells. Tube formation in vitro was evaluated in coculture systems of human umbilical vein endothelial cells (HUVECs) and rat degenerated NP cells (DNPCs). Inflammatory response was assessed from levels of TNF-γ, IL-1, and IL-6 and neovascularization from expression of endothelial growth factor (VEGF). The P14ARF and TIMP3 were downregulated in degenerated IVD tissue derived from patients and experimental IVDD rats. Overexpressed P14ARF suppressed inflammatory cytokine levels and vascularization. There was decreased in vitro tube formation in response to P14ARF overexpression and TIMP3 elevation. Finally, attenuated inflammatory responses and suppression of VEGF were achieved by P14ARF-mediated promotion of TIMP3 in rat DNPCs. Taken together, the present study reveals that P14ARF/TIMP3 modulation of inflammatory response and vascularization in the context of IVDD highlights a potential target for future therapeutic strategies. [ABSTRACT FROM AUTHOR]