Conclusion
The current study indicated that calcitriol could inhibit the priming stage of HS-induced cellular inflammation, highlighting its potential capacity to prevent and mitigate dry eye related corneal inflammation at an earlier stage.
Methods
Human corneal epithelial cells (iHCECs) were cultured in hyperosmotic medium (450 mOsM) with various concentrations of calcitriol. Small interfering RNA (siRNA) was used to knock down the expression of vitamin D receptor (VDR) in iHCECs. NLRP3 activation and IL-1β generation were detected by RT-qPCR or ELISA, respectively. Oxidative stress markers including ROS and 8-OHdG were examined by fluorometric analysis. The nuclear translocation of NRF2 was assessed by western blotting.
Purpose
The activation of ROS-NLRP3-IL-1β signaling axis induced by hyperosmotic stress (HS) has been recognized as a key priming stage of epithelial inflammation in dry eye pathogenesis. The current study aims to investigate whether calcitriol, the active metabolite of vitamin D3, could protect cells against HS-induced inflammation through modulating this critical step.
Results
Calcitriol could protect cells against HS-induced injury through inhibiting ROS-NLRP3-IL-1β signaling axis. Calcitriol remarkably suppressed the expression of NLRP3 inflammasome related genes and the production of IL-1β in cells that were exposed to HS. It could also significantly attenuate HS-induced oxidative stress, shown as the reduced intracellular ROS generation and 8-OHdG staining cells after calcitriol treatment. Calcitriol induced the translocation of NRF2 to the nucleus, and thereby triggered the expression of several antioxidant enzymes.