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Adrienne Clark, Alexandra Bernardo, Tonia S Rex; Closed globe trauma activates sterile inflammation in the retina. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1762. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Our goal was to determine if ocular trauma activates sterile inflammation in the retina.
We exposed one eye of an anesthetized C57Bl/6 mouse to a burst of overpressure air. Sham mice were anesthetized and placed into the air blast system, but were not exposed to the overpressure air. At multiple time-points after injury tissue was collected for immunohistochemistry, Western blot analysis, and multiplex ELISA to assess activation of sterile inflammation.
In the C57Bl/6 mouse, cell death, axon degeneration, and vision loss are first detectable at 1 month after eye trauma in our model. Sterile inflammation can be initiated by the alarmin, Il-1a. Levels of IL-1a were increased at 2 weeks and further increased at 4 weeks after injury as compared to shams. The caspase that mediates sterile inflammation is caspase-1. Levels of caspase-1 were detected in Chat-positive amacrine cells beginning as early as 3 days after ocular trauma and total retina levels of total and cleaved caspase-1 were also increased after injury. The extent of retina with caspase-1 immunolabeling increased over time after injury from a focal area at 3 days to throughout the retina at 1-month. Activation of IL-1R by IL-1a or IL-1b induces increases in IL-1b and IL-18, which are both cleaved into their active forms by caspase-1. Both IL-1b and IL-18 were increased at 1-month after injury as compared to shams.
Prior to detection of neurodegeneration and vision loss in the retina there was an increase in the pro-inflammatory cytokine and “alarmin”, IL-1alpha. In addition, increases in cleaved caspase-1 and Il-1b and IL-18 point towards a role of sterile inflammation after eye trauma. Interestingly the caspase-1 labeling was specific to the Chat-positive, i.e. starburst, amacrine cells. Thus these neurons, rather than glial/immune cells may be mediating this response to injury. Future studies are needed to determine if these secreted pro-inflammatory cytokines are responsible for the cell death, axon degeneration, and vision loss detected after ocular trauma in our model.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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