title: T-cell suppression by programmed cell death 1 ligand 1 on retinal pigment epithelium during inflammatory conditions.
abstract: OBJECTIVE
  To determine whether retinal pigment epithelial (RPE) cells can inhibit in vitro T-cell activation during inflammatory conditions.
  
  
  METHODS
  Primary cultured RPE cells were established from normal C57BL/6 mice. Target bystander T cells were established from normal splenic T cells with anti-CD3 antibodies. T-cell activation was assessed for proliferation by both examining [(3)H]-thymidine incorporation and the production of interferon (IFN)gamma or IL-17, as determined by ELISA. Expression of programed cell death 1 ligand 1 (PD-L1) on RPE or recombinant mouse IFNgamma-pretreated RPE cells was evaluated using oligonucleotide microarray, RT-PCR, immune staining, and flow cytometry. Expression of programed cell death 1 (PD-1)(+) on target T cells was evaluated by flow cytometry. Anti-mouse PD-L1 or PD-L2 neutralizing antibodies or target T cells from PD-1 knockout donors were used for the assay.
  
  
  RESULTS
  IFNgamma-pretreated RPE greatly suppressed activation of bystander T cells, especially the IFNgamma production by the target T cells (Th1 cells, but not Th17 cells) via direct cell contact. By examining cell surface candidate molecules, IFNgamma-pretreated RPE expressed much higher levels of PD-L1 compared with the control nontreated RPE. Although primary RPE did not express the costimulatory molecule, expression of the molecule was induced on the surface of IFNgamma-pretreated RPE. PD-L1(+) RPE in the presence of IFNgamma selectively suppressed PD-1(+) T-cell activation. IFNgamma-pretreated RPE in the presence of anti-PD-L1 neutralizing antibodies, but not anti-PD-L2, failed to suppress T-cell production of IFNgamma. In addition, these RPE cells failed to suppress the production of IFNgamma by CD4(+) T cells from PD-1 null donors.
  
  
  CONCLUSIONS
  Suppression of T-cell activation was obtained in cultures only when RPE expressed negative costimulators. Therefore, the authors propose that in vitro, Th1 cytokine-exposed ocular resident cells can express this molecule and it is this expression that causes the suppression of the bystander Th1-type cells.
authors.affiliation: Department of Ophthalmology & Visual Science, Tokyo Medical and Dental University Graduate School, Tokyo, Japan. sunaoph@tmd.ac.jp
authors.forename: Sunao
authors.initials: S
authors.lastname: Sugita
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Usui
authors.forename: Shintaro
authors.initials: S
authors.lastname: Horie
authors.forename: Yuri
authors.initials: Y
authors.lastname: Futagami
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Aburatani
authors.forename: Taku
authors.initials: T
authors.lastname: Okazaki
authors.forename: Tasuku
authors.initials: T
authors.lastname: Honjo
authors.forename: Masaru
authors.initials: M
authors.lastname: Takeuchi
authors.forename: Manabu
authors.initials: M
authors.lastname: Mochizuki
mesh_terms: D000818:Animals; D001327:Autoimmune Diseases / Q000139:chemically induced / Q000276:immunology*; D018122:B7-1 Antigen / Q000502:physiology*; D060890:B7-H1 Antigen; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005136:Eye Proteins; D005434:Flow Cytometry; D015870:Gene Expression; D006801:Humans; D007124:Immunoenzyme Techniques; D007165:Immunosuppression Therapy; D007371:Interferon-gamma / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020411:Oligonucleotide Array Sequence Analysis; D010455:Peptides / Q000502:physiology*; D055213:Retinal Pigment Epithelium / Q000187:drug effects / Q000378:metabolism*; D012177:Retinol-Binding Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014605:Uveitis / Q000139:chemically induced / Q000276:immunology*; D000099214:Retinol-Binding Proteins, Interstitial
chemical_list: D018122:B7-1 Antigen; D060890:B7-H1 Antigen; D005136:Eye Proteins; D007371:Interferon-gamma; D008562:Membrane Glycoproteins; D010455:Peptides; D012177:Retinol-Binding Proteins; D000099214:Retinol-Binding Proteins, Interstitial; C498919:Cd274 protein, mouse