Abstract
Purpose :
Nerves and specialized pro-resolving mediators (SPMs) regulate mucin secretion from conjunctival goblet cells to maintain ocular surface homeostasis and health. To identify signaling pathways activated, we explored actions of the SPM resolvin E1 (RvE1) on cultured rat conjunctival goblet cell intracellular [Ca2+] ([Ca2+]i) and mucin secretion.
Methods :
Goblet cells were cultured from male rat conjunctiva. To detect whether RvE1 receptors ChemR23/ERV and BLT1 were located in goblet cells, RT-PCR was performed. RvE1-stimulated mucin secretion was determined using an enzyme-linked lectin assay. siRNA was used to examine if ChemR23/ERV and BLT1 were needed to increase RvE1-stimulated [Ca2+]i and mucin secretion. Signaling pathways activated by RvE1 in goblet cells were studied by measuring increase in [Ca2+]i using fura 2/AM.
Results :
The RvE1 receptors ChemR23 and BLT1 were both detected in rat conjunctival goblet cells. In the presence of Ca2+ chelator Bapta/AM RvE1 stimulated mucin production was significantly blocked. siRNA for ChemR23/ERV and BLT1 each significantly blocked RvE1 stimulated increase in secretion. Use of the inhibitors U73122, 1-butanol, and aristolochic acid for phospholipase (PL)C, PLD and PLA2, respectively each blocked RvE1 increase in [Ca2+]i. We also showed that RvD1 increase in [Ca2+]i was blocked by the BLT1 inhibitor LY29311 and that stimulation with either RvE1 or RvD1 desensitized the opposite SPM’s increase in [Ca2+]i.
Conclusions :
RvE1 uses ChemR23/ERV and BLT1 to stimulate conjunctival goblet cells to secrete mucin through activation of multiple PL pathways that increase [Ca2+]i. In addition, RvE1 and RvD1 may both activate the same receptor, perhaps BLT1, in addition to their own receptors ChemR23/ERV and GPR32/DRV1.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.