Extraorbital lacrimal and Harderian glands excision in mice: a new pre-clinical animal model of dry eye.

Abstract

Purpose : The pathophysiology of ocular pain in dry eye disease remains unclear and few reproducible animal models exist to explore it. Our objective was to develop a new pre-clinical mouse model of dry eye and to evaluate its consequences on the trigeminal pathway.

Methods : Extraorbital lacrimal and Harderian glands were surgically removed in female C57BL/6 mice (n=6; unilateral excision). Another group of female C57BL/6 mice underwent a sham procedure (n=5). This experiment was conform to the ARVO statement for the use of animals. All mice had an ocular surface evaluation including a fluorescein test, a phenol red-thread test and an in vivo confocal microscopy analysis of the cornea at day 0, 7, 14 and 21. We also evaluated the expression of inflammatory chemokines by RT-qPCR in the ipsilateral trigeminal ganglion (TG) and in the sensory trigeminal complex (SP5) at day 21.

Results : Lacrimal and Harderian glands excision induced mild to severe dry eye with decrease tear production, severe keratitis observed with slit lamp and inflammation in the corneal stroma observed with in vivo confocal microscopy. In the ipsilateral trigeminal ganglion, no significant change was observed in the expression of inflammatory markers (TNF-alpha, IL-6 and CCL2). In the sensory trigeminal complex, we found a significant increase in the expression of TNF-alpha (+63.1%; p=0.017), CCL2 (+60.4%; p=0.0087) in dry eye mice as compared to the control group. We also found a significant increase in the expression of neuronal injury marker ATF3 (+90.1%; p=0.0043) and activating neuronal marker C-FOS (+64.3%; p=0.0043). The expression of IL-6 in the sensory trigeminal complex was not significantly different in dry eye mice as compared to the control group (+22.4%; p=0.87).

Conclusions : This new experimental model of dry eye showed mild to severe alterations of the ocular surface. Extraorbital lacrimal and Harderian glands excision induced peripheral (cornea) and central (sensory trigeminal complex) inflammation that may play a significant role in ocular pain development.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.