Abstract
Purpose: :
Ocular immune privilege allows for immune protection in the eye while suppressing inflammation. Previous studies from our laboratory showed that ACAID is lost as early as 6h and as late as 21D post retinal laser burn (RLB). Here we examined the effect of retinal laser burn (RLB) on the immunosuppressive environment of the eye.
Methods: :
RLB was performed by delivering 4 laser spots (diode laser) to the right eye of C57BL/6 mice. mRNA was extracted from the eye (excluding the lens) of RLB or non-treated mice and evaluated for IL-6. To examine the role of IL-6 in the loss of immune privilege after RLB, Anterior Chamber Associated Immune Deviation (ACAID) was induced in C57BL/6 or IL-6KO mice by an anterior chamber (a.c.) injection of OVA followed by s.c. immunization and ear challenge. ACAID tolerance was induced if delayed-type hypersensitivity response was suppressed. To test the immunosuppressive properties of the retina, eyes were removed from RLB or non-treated mice. Eyecups were made from the RPE containing posterior part of the eye (excluding the neural retina). Naïve T-cells were incubated with non-treated or RLB eyecups for 48h, collected and analyzed by flow cytometry for FoxP3 expression.
Results: :
RTPCR analyses of mRNA extracted from experimental and control eyes showed an increase of IL-6 in the RLB eye, but not non-treated eye. ACAID was lost in C57BL/6 as well as IL-6KO mice post-RLB. Additionally, T-cell incubated with RLB eyecups had fewer Foxp3 expressing (T regulatory) T-cells compared to T-cells incubated with non-treated eyecups.
Conclusions: :
Previous data from our laboratory suggest that RLB alters the immunosuppressive environment of the eye. We observe an increase in the inflammatory cytokine, IL-6 after RLB, however IL-6KO mice still lost ACAID after RLB. Taken together these data suggest IL-6 may be working in tandem with other inflammatory cytokines in the loss of ACAID. New data show that RLB may alter the immunosuppressive ability of the RPE cells since coculture with T cells produce less Treg cells ( FoxP3+).
Keywords: ACAID • laser • retina