Abstract
Purpose: :
To examine the dynamic changes in resident and infiltrating myeloid cells and putative dendritic cells (DCs) in the retina in Experimental Autoimmune Uveitis (EAU) in Cx3Cr1+/GFP and CD11c-YFP mice using in vivo clinical fundus observations and fluorescein angiography, and to correlate the clinical disease progression with histopathologic changes.
Methods: :
EAU was induced by immunization with IRBP 1-20 in complete Freund’s adjuvant and pertussis toxin in C57BL/6 Cx3cr1+/GFP and CD11c -YFP mice. Animals were imaged with a Micron III fundus camera (brightfield and fluorescence) on Day 14, 21, 28, and 35 post-immunization. On Day 35 eyes were processed for resin histology.
Results: :
In the normal fundus of Cx3CR1-GFP mice the GFP+ retinal microglia network is clearly discernable using in vivo fluorescence ophthalmoscopy. In CD11c-YFP mice a less dense network of YFP+ microglia-like cells are also detectable. Whole mounts confirmed that 18.75 % (+/- 2.7 SEM) of Iba-1+ microglia are CD11c+. In Cx3cr1-GFP mice evidence of mild disease was clinically detectable around Day 28 as vasculitis, perivascular cuffing and focal infiltrates of Cx3cr1+ cells. This was more severe by Day 35 and was accompanied by fluorescein leakage in fluorescein angiography. In CD11c-YFP mice more severe disease and earlier onset (Day 14) was noted. As the disease progresses, increased vascular permeability corresponded to marked accumulation of CD11c+ cells which in turn was seen in microscopic analysis to correspond to cuffing, monocytic perivascular infiltrates and focal mononuclear nodular lesions of the RPE and photoreceptor layer. Marked iridocyclitis was also a feature of EAU in both strains.
Conclusions: :
The results demonstrate that in vivo clinical brightfield and fluorescent fundus imaging can be used to accurately chart the myeloid cell inflammatory cell infiltrate in EAU. The observations from in vivo fundus imaging correlate with the histopathology of EAU and in particular highlight an intense infiltration of putative DCs in the early stages of the disease. The difference in disease progression and severity between the two transgenic mouse lines (both on C57BL/6 background) may be the result of different husbandry conditions in the two colonies.
Keywords: pathology: experimental • uveitis-clinical/animal model • imaging/image analysis: non-clinical