Sympathetic Neurotransmitter, VIP, Delays Intervertebral Disc Degeneration via FGF18/FGFR2‐Mediated Activation of Akt Signaling Pathway

Abstract Neuromodulation‐related intervertebral disc degeneration (IVDD) is a novel IVDD pattern and are proposed recently. However, the mechanistic basis of neuromodulation and intervertebral disc (IVD) homeostasis remains unclear. Here, this study aimed to investigate the expression of postganglionic sympathetic nerve fiber‐derived vasoactive intestinal peptide (VIP) system in human IVD tissue, and to assess the role of VIP‐related neuromodulation in IVDD. Patient samples and in vitro cell experiments showed that the expression of receptors for VIP is negatively correlated with the severity of IVDD, and the administration of exogenous VIP can ameliorate interleukin 1β‐induced nucleus pulposus (NP) cell apoptosis and inflammation. Further mRNA‐seq analysis revealed that fibroblast growth factor 18‐ (FGF18)‐mediated activation of V‐akt murine thymoma viral oncogene homolog signaling pathway is involved in the protective effects of VIP on inflammation‐induced NP cell degeneration. Further analysis identified VIP via its receptor vasoactive intestinal peptide receptor 2 can directly result in decreased expression of miR‐15a‐5p, which targeted FGF18. Finally, in vivo mice lumbar IVDD model confirmed that focally exogenous administration of VIP can effectively ameliorated the progression of IVDD, as shown by the radiological and histological analysis. In conclusion, these results indicated that sympathetic neurotransmitter, VIP, delayed IVDD via FGF18/FGFR2‐mediated activation of V‐akt murine thymoma viral oncogene homolog signaling pathway, which will broaden the horizon concerning how the neuromodulation correlates with IVDD and shed new light on novel therapeutical alternatives to IVDD.