Abstract
Purpose:
The purpose of this study is to determine the tissue-specific response and temporal kinetics of the inflammatory response in the mouse eye, using the endotoxin-induced uveitis (EIU) murine model.
Methods:
Two groups of age-matched C57BL/6J mice (N=12) received ocular injections (10 µL) of either lipopolysaccharide (LPS, 1µg/µL) or phosphate buffered saline (PBS) into the anterior chamber. Control (untreated) eyes received no injection. Mice were sacrificed at 0 (untreated controls), 3, 6, or 16 hours after injection. The mice were perfused with PBS and the eyes were enucleated. Ocular tissue was dissected, separating the iris, retina and retinal pigment epithelial (RPE). Tissue homogenates underwent analysis by Cytometric Bead Array (CBA, BD Biosciences) to determine the inflammatory response at each interval. The markers used to determine the extent of inflammation were Tissue Necrosis Factor-alpha (TNF-α) and Interleukin 6 (IL-6).
Results:
Injection with LPS induced expression of IL-6 in all ocular tissues. In the iris, peak IL-6 response occurred at 6 hours, and was ~400 fold higher than PBS injected controls. In the retina, peak IL-6 response occurred at 16 hours, and was ~120 fold higher than PBS injected controls. In the RPE, peak IL-6 response occurred at 16 hours, and was ~140 fold higher than the PBS injected controls. For TNF-α, peak production occurred at 3 hours in the iris and retina, and 6 hours in the RPE. Values were 10 to 80% higher than untreated tissue; however, these values were unchanged when comparing PBS to LPS. Injection with either PBS or LPS increased cytokine production over untreated controls, suggesting the trauma induced by the injection was sufficient to elicit a cytokine response.
Conclusions:
Our results indicate significant tissue-specific responses in the EIU animal model. The inflammatory response, as determined by IL-6 production, was the greatest in the iris, and slightly less in RPE and the retina. Peak response of IL-6 occurred at 6 hours in the iris and RPE, and 16 hours in retina.
Keywords: 746 uveitis-clinical/animal model •
490 cytokines/chemokines •
557 inflammation