Abstract:Objective: To construct an isolated model of knee osteoarthritis (KOA), which is co-cultured by dorsal root ganglion (DRG) and fibroblast-like synoviocytes (FLSs). To investigate the effect mechanism of transient receptor potential vanilloid type 1 (TRPV1) desensitization of sensory neurons induced by benign mechanical stimulation and its alleviation of FLSs inflammatory response. Methods: DRG neuronal cells were identified by immunofluorescence method. The stress loading of DRG neurons was realized by FX-6000T cell stress system, and the effect of mechanical stress on the activity of DRG neurons was measured by CCK-8 method. The calcium flux of DRG neurons in each group was studied by flow cytometry. Transwell chamber and FLSs were used to establish a co-culture system. The contents of pro-inflammatory factors IL-1β, TNF-α and TGF-β in the supernatant were determined by ELISA. The gene and protein expression levels of TRPV1 and its desensitizing negative regulatory proteins PP2B, CaM, IL-1β, TNF-α, TGF-β and α-SMA in DRG neurons were detected by PCR and WB, respectively. Results: The Ca2+ ion flux in DRG neurons increased under inflammatory environment, and the medium and high intensity mechanical stimulation further increased the Ca2+ ion flux (P<0.05), but the high intensity finger pressure did not further increase the medium intensity Ca2+ ion flux (P>0.05). Moderate and high intensity benign mechanical stimulation up-regulated TRPV1 gene and protein expression of DRG neurons in inflammatory group (P<0.05), but down-regulated PP2B and CaM gene and protein expression; Moderate and high intensity benign mechanical stimulation decreased the contents of IL-1β, TNF-α and TGF-β in the supernatance of co-cultured cells (P<0.05), and down-regulated the gene and protein expressions of IL-1β, TNF-α, TGF-β and α-SMA in FLSs (P<0.05). Conclusion: Moderate and high intensity benign mechanical stimulation induced TRPV1 desensitization of rat sensory neurons, and inhibited FLSs inflammatory response through intercellular communication.