Abstract
Purpose :
Various environmental and pharmacological murine models of dry eye have been proposed that may differ in the degree and pattern of immune activation. This study compared desiccating stress (DS) without or with pharmacologic inhibition of tear secretion (DST) on the initial immune response.
Methods :
6-to-8-week-old non-stressed C57BL/6J mice were housed under ambient relative humidity (NS) and left untreated or subjected to DS (low humidity and air draft) or DST (low humidity, air draft systemic scopolamine to inhibit tear secretion) for 1 day (D1). Expression of IFN-g signature (IL-12, IFN-g and Sprr2g) and IL-17A genes were evaluated in the conjunctiva and cornea by real-time PCR. Percentages of CD45+CD11b+IL-12+, CD45+CD11b+p-STAT4+, CD45+CD3+IFN-g+ and CD45+CD3+IL-17+ cells were analyzed in the cervical lymph nodes (CLNs) by flow cytometry.
Results :
There was no change in expression of IL-12, IFN-g and IL-17A in the conjunctiva on D1 in the DS and DST groups. In the cornea, IFN-g and IL-17A expression significantly increased in the DST group (P<0.0001 for both), but there was no difference in IL-12 between groups. Sprr2g, an IFN-g induced cornified envelope gene, was higher in the conjunctiva and cornea in DST group compared to DS only (P<0.0001 for both). Compared to the NS group, there was a greater frequency of CD45+CD11b+IL-12+ cells in the CLN of the DST group compared to DS at D1 (P<0.008). The percentage of CD45+CD11b+p-STAT4+cells in DS was significantly higher than NS (P<0.02), while the percentage of these cells in the DST group was significantly higher than both DS and NS groups (P<0.006 for both) in the CLNs. There were no between group differences for IFN-g+ or IL-17+ CD3+ cells in the CLN at D1.
Conclusions :
These findings indicate that murine environmentally-induced dry eye models differ in the level of initial immune response. DST produced more robust activation of the IL-12/STAT4 pathway in innate immune cells and in level of IFN-g and IL-17A expression in the cornea. They also suggest IL-12/STAT4 signaling pathway may be a novel therapeutic target for inhibiting desiccation induced ocular surface inflammation.
This is a 2020 ARVO Annual Meeting abstract.