Abstract
Purpose :
As an ocular surface tissue, conjunctival epithelium lines the inside of the eyelids and covers the sclera, thus providing stability to the anterior segment of the eye. The conjunctival goblet cells (CGCs) secrete mucins to wet and protect the ocular surface, of which under- or over-secretion due to inflammation causes visual disturbance. Therefore, time-dependent resolution of conjunctival inflammation is critical for a transparent cornea and clear vision. Extracellular bioactive lipid mediators, especially the specialized pro-resolving and proinflammatory lipid mediators (SPMs and PIMs, respectively), are one of the factors that mediate the progression and resolution of conjunctival inflammation. To better understand the cellular response of CGCs in resolving inflammation, we investigated whether (1) CGCs synthesize and secrete SPMs and PIMs via extracellular vesicles (EVs), (2) their amount change during allergic inflammation, and (3) there is a sex difference in the secretion of SPMs and PIMs.
Methods :
Primary CGCs outgrown from human conjunctival tissue explants were stimulated with 10-4 M histamine for 18 h. EVs isolated from the collected culture media were analyzed using ELISA for two types of SPMs (resolvin D1 (RvD1) and lipoxin A4 (LXA4)) and one type of PIMs (prostaglandin E2 (PGE2)). By using an equal number of male and female human conjunctival tissues (n=3), the sex difference in cellular response during histamine-mediated allergic inflammation was observed.
Results :
EVs collected from CGC culture media after 18 h of histamine stimulation contained a 7-fold higher amount of RvD1, 5-fold* of LXA4, and 2-fold of PGE2, compared to the non-treated controls. Interestingly, these increases in fold change were only observed in females, but not in males. EVs collected from males under the same condition showed a slight decrease in the amounts of RvD1 (0.8-fold) and LXA4 (0.4-fold*) compared to the control (*statistically significantly different from the control).
Conclusions :
We conclude that CGCs biosynthesize and secrete SPMs and PIMs via EVs, and their amount in EVs significantly changes during allergic inflammation in a sex-dependent manner. The observed sex difference warrants further investigation as this could explain the sex difference in incidence and severity of ocular allergy observed in the clinic.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.