A pilot feasibility study for using in vivo bioluminescence imaging for longitudinal monitoring of inflammation in a rodent model of uveitis

Abstract

Purpose : Due to the size of rodent eyes, ocular inflammation is difficult to assess without sacrificing the animal for histology. In Vivo Imaging System (IVIS) facilitates non-invasive longitudinal monitoring of disease progression using bioluminescence. This pilot study explores the feasibility of using IVIS bioluminescence as an objective nonlethal assay for use in animal models of uveitis.

Methods : Acute inflammation was induced in four 2-month-old female C57BL/6 mice by systemic injection of 100 ug of a killed mycobacterial extract in adjuvant on day -7 followed by intravitreal injection of 5 ug of the extract in PBS on day 0. Imaging was performed prior to eye injection on day 0 and on days 2, 7, 14, and 21. Bioluminescence was generated using the XenoLight RediJect^® myeloperoxidase luminescence probe. Images were captured by a PerkinElmer IVIS Spectrum and radiance was analyzed using Living Image software. Select animals were sacrificed and eyes collected at each time point to confirm inflammation by histology.

Results : Histology confirmed inflammation at terminal imaging for each animal. Bioluminescence peaked on day 2 in two animals and on day 7 in two animals. The maximum increase of radiance over baseline was 2.01x10⁴ p/s/cm²/sr and the average increase for all animals was 7.25x10³ p/s/cm²/sr. In animals with day 2 peaks, radiance returned to near baseline by day 14. In animals with day 7 peaks, radiance initially declined by day 14, but then plateaued. Non-injected eyes did not demonstrate an increase in radiance over time.

Conclusions : This pilot study demonstrates that acute intraocular inflammation in a mouse model of uveitis is detectable using myeloperoxidase-based bioluminescence imaging. Two patterns of peak inflammation were detected: acute elevation by day 2 with rapid resolution, and a day 7 peak with a prolonged course. Future studies will be required to explore the physiologic basis for these two patterns of inflammation, and to optimize detection of inflammation induced bioluminescence.

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

 

A) Day two bioluminescence image of an inflamed eye. B) Average radiance in the eye region of interest (ROI) during acute uveitis in the inflamed eye (blue) and uninflamed eye (red).