Abstract
Purpose: :
Autoimmune uveitis, a leading cause of visual impairment, is a T cell-mediated disease characterized by infiltration of inflammatory cells into the uvea. Through the use of non-invasive, intravital microscopy, we examined the temporal dynamics of infiltrating antigen-specific and non-specific T cells into the iris in a model of uveitis.
Methods: :
Mice expressing GFP under the actin promoter were crossed with DO11.10 TCR transgenic mice, producing donor mice with fluorescent green CD4+ T cells specific for OVA peptide. At least one week prior to splenectomy, mice were immunized with OVA peptide (100 µg) via ip injection. After whole splenocyte harvest, cells were cultured in the presence of OVA peptide (2 µg/ml) for 5 days. CD4+ T cells were purified and 20 million cells were transferred via tail vein injection into recipient congenic mice expressing dsRED under a T cell promoter. Recipient mice were subsequently challenged via intravitreal injection of endotoxin (200 ng) and 50 µg of ovalbumin or BSA. Infiltrating T cells were recorded via in vivo videomicroscopy and analyzed.
Results: :
Infiltrating antigen-specific (green) and non-specific (red) T cells accumulated in the iris of the antigen-challenged eye within several hours of intravitreal injection, peaking at 12-24 hours post injection (611/mm2+/-208). The infiltration was far less pronounced in the BSA-challenged contralateral eye (16.9/mm2+/-10). The fluorescent cell density remained roughly constant for 3 days before diminishing over the next couple of days and disappearing by 5 to 7 days. The ratio of non-specific to antigen-specific cells was initially 1.9 at 24 hours, and over the course of the inflammatory process progressed to 0.8 and 1.1 at 48 hours and 4 days, respectively. Preliminary clodronate depletion experiments suggest a role for macrophages in the recruitment of both cell types to the antigen-challenged eye. Many fluorescent green and red cells accumulated in the limbal regions of ovalbumin-challenged and, to a lesser extent, BSA-challenged eyes during the initial phase (0-7 days), after which few antigen-specific cells persisted. In the limbal regions, host cells continued to be observed in greater numbers than in control eyes up to 42 days after antigen challenge.
Conclusions: :
Intravital examination of our model demonstrates the presence of many non-specific host cells during the acute and convalescent phases of the inflammatory process. This system presents a promising platform for examining the cellular and molecular determinants of antigen-specific and non-specific cell recruitment as well as their role(s) in the pathologic process.
Keywords: uveitis-clinical/animal model • autoimmune disease • inflammation