Purpose:
Previous work has shown more severe inflammation in pigmented mice with experimental autoimmune uveitis. The purpose of the current study was to compare disease characteristics between pigmented and albino mice with endotoxin induced uveitis (EIU) as determined by inflammatory cell infiltration patterns into the anterior segment of the eye.
Methods:
Wild-type pigmented (C57BL/6J) and albino (C57BL/6J-Tyrc-2J) mice from Jackson Laboratories were induced for EIU by an intravitreal injection with 250 ng of E. coli endotoxin. Mice were humanely euthanized and sacrificed at 9 and 18 hr post induction, and both eyes enucleated and snap frozen in OCT. Cryosections (8 uM) were taken from the pupillary optic nerve axis and stained with H&E. Inflammatory cells infiltrating into the anterior chamber angle in 6 cryosections were counted by a single observer and averaged for each animal. The Wilcoxon Rank Sum test was used to compare cell counts between animal type and time period.
Results:
There was no significant difference between the two groups with respect to the time-related increases in cell counts. However, with respect to neutrophils, there was a larger, though not statistically significant, time-related increase among the pigmented eyes compared to the albino animals. This change in neutrophils accounted for the majority of the difference in total cells seen at 18 hours compared to 9 hours. Significance was found for the change between 9 and 18 hours in infiltrating macrophages and lymphocytes (Table 2).
Conclusions:
Neutrophil infiltration timing differed between albino and pigmented wild type mice over time in animals induced for EIU. The presence of melanin in the eye of pigmented mice may exert an effect on cell trafficking into the eye in the endotoxin uveitis model.
Keywords: uveitis-clinical/animal model • inflammation • anterior segment