Regulatory role of TLR ligands on the activation of autoreactive T cells by retinal astrocytes.
OBJECTIVE
To determine whether Toll-like receptor (TLR) ligands regulate the activation of retinal astrocytes (RACs) and the possible role of RACs in the polarization of interphotoreceptor retinoid-binding protein (IRBP)-specific T cells.


METHODS
TLR expression on RACs isolated from C57BL/6 mice was examined using real-time PCR and flow cytometry. The ability of RACs before or after treatment with TLR ligands to interact with T cells was assessed by measuring major histocompatibility complex class II and costimulatory molecule expression and cytokine production. The stimulatory effect of RACs, with or without TLR stimulation, on responder IRBP-specific T cells was examined by T-cell proliferation, cytokine production, and disease-inducing ability.


RESULTS
Cultured mouse RACs expressed TLR2, TLR3, and TLR4. Different TLR ligands had distinct stimulatory effects on RACs. PolyI:C (a TLR3 ligand) had the greatest effect in stimulating RACs to acquire antigen-presentation function, whereas BLP (a TLR2 ligand) had the lowest effect. TLR3 ligation increased the expression of MHC and costimulatory molecules and induced the production of IL-6, IL-12, and IL-23 by RACs. IRBP-specific T cells activated by polyI:C-treated RACs expanded vigorously, produced significant amounts of IFN-gamma and IL-17, and induced experimental autoimmune uveitis when injected into naive mice.


CONCLUSIONS
The stimulatory effect of RACs on autoreactive T cells is regulated by TLR ligands. TLR3 had a marked effect on the ability of RACs to promote the activation of Th1 and Th17 IRBP-specific T cells. Thus, exposure to microbial antigen(s) may alter susceptibility to autoimmune uveitis by promoting the activation of autoreactive T cells.
Jiang
Guomin
G
Department of Ophthalmology and Visual Sciences, Kentucky Lions Eye Center, University of Louisville, Louisville, Kentucky 40202, USA.
Ke
Yan
Y
Sun
Deming
D
Wang
Yali
Y
Kaplan
Henry J
HJ
Shao
Hui
H
D019264:Adoptive Transfer; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D001253:Astrocytes / Q000502:physiology*; D001327:Autoimmune Diseases / Q000276:immunology*; D018122:B7-1 Antigen / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D018920:Coculture Techniques; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology; D005136:Eye Proteins; D005260:Female; D005434:Flow Cytometry; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D008024:Ligands; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000378:metabolism; D055351:Retinal Neurons / Q000502:physiology*; D012177:Retinol-Binding Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051193:Toll-Like Receptors / Q000502:physiology*; D014605:Uveitis / Q000139:chemically induced / Q000276:immunology; D000099214:Retinol-Binding Proteins, Interstitial
D018122:B7-1 Antigen; D016207:Cytokines; D005136:Eye Proteins; D000949:Histocompatibility Antigens Class II; D008024:Ligands; D012333:RNA, Messenger; D012177:Retinol-Binding Proteins; D051193:Toll-Like Receptors; D000099214:Retinol-Binding Proteins, Interstitial