TRPV2 mediates mechanical stress-induced IL-8 release in odontoblasts

Objectives: The objectives of the current study were to determine whether exposure of odontoblast-like cells to mechanical stress was capable of eliciting an inflammatory response. We have previously demonstrated the presence of the mechanosensitive ion channel transient receptor potential vanilloid 2 (TRPV2) on odontoblast-like cells and the focus of this work was to investigate a novel role for TRPV2 in mechanical stress-induced inflammatory cytokine release in odontoblasts.
Methods: Human dental pulp cells were cultured in the presence of 2 mM β-glycerophosphate to induce an odontoblast phenotype. Odontoblast-like cells were seeded in 24-well plates and exposed to centrifugation force (475g/cm) for 20 min. To evaluate the effect of mechanical force on cytokine release we undertook a custom-designed human cytokine magnetic luminex screening assay according to the manufacturer’s instructions (R&D Systems).
Results: Exposure of odontoblasts to pressure force resulted in modest but significant increase in release of the pro-inflammatory cytokine IL-8, but there was no significant change in TNF-alpha, IL-1 beta, IFN-gamma or IL-1 receptor antagonist levels. We were not able to detect measurable levels of IL-10 in this assay. To evaluate the effect of pharmacological activation of TRPV2 on IL-8 release, cells were treated with a specific agonist for TRPV2 (cannabidiol), which dose dependently increased IL-8 release in odontoblast-like cell supernatant. This effect was inhibited by the specific TRPV2 antagonist, tranilast. Further confirmation of a specific role for TRPV2 in mechanical stress induced IL-8 release was obtained in SiRNA treated cells in which IL-8 release was reduced following exposure to force.
Conclusions: These results provide the first evidence for a functional role of TRPV2 in human odontoblast-like cells in mediating mechanical injury induced pulpal inflammation, providing further support for the role of odontoblast TRP channels in pulpal physiology.