title: HMGB1 release triggered by the interaction of live retinal cells and uveitogenic T cells is Fas/FasL activation-dependent.
abstract: BACKGROUND
  It is not clear how invading autoreactive T cells initiate the pathogenic process inside the diseased organ in T cell-mediated organ-specific autoimmune disease. In experimental autoimmune uveitis (EAU) induced by adoptive transfer of interphotoreceptor retinoid-binding protein (IRBP)-specific T cells in mice, we have previously reported that intraocular inflammation was initiated by infiltrating IRBP-specific T cells that directly interacted with retinal cells and resulted in the active release of high mobility group box 1 (HMGB1), an important member of damage associate molecular patterns (DAMPs). Furthermore, blockade of HMGB1 in our murine model reduced intraocular inflammation via suppression of IRBP-specific T cell functions. These results have demonstrated that HMGB1 is an early and critical mediator of induction of intraocular inflammation. The present study identified the cell surface molecule that triggers HMGB1 secretion.
  
  
  METHODS
  Retinal explants from Fas-deficient (Fas(lpr)) and wild-type (Wt) C57BL/6 (B6) mice were cultured with activated IRBP 1-20 peptide-specific T cells or with a Fas-activating antibody (Jo2), and then the level of HMGB1 in culture supernatants were detected by ELISA. In addition, released HMGB1 was examined in the eye of Fas(lpr) and Wt mice after IRBP-specific T cell transfer. Uveitis was evaluated in the IRBP-specific T cell transferred Fas(lpr) mice after recombinant HMGB1 was restored within the eye and in the IRBP-specific T cell transferred Wt mice after they were treated with a Fas antagonist (Met12).
  
  
  RESULTS
  In contrast to retinal explants from Wt mice, those from Fas(lpr) mice did not release HMGB1 after exposure to IRBP-specific T cells or to Jo2. The release of HMGB1 by Wt retinal explants was suppressed by Met 12. Moreover, after IRBP-specific T cell injection, Fas(lpr) mice did not release HMGB1 in the eye or develop EAU, but intravitreous injection of HMGB1 resulted in intraocular inflammation. Finally, tEAU in Wt mice was attenuated by local treatment with Met 12. Unlike HMGB1, Fas-induced IL-1 and IL-18 were not essential for tEAU induction.
  
  
  CONCLUSIONS
  Our results show that interaction of retinal cells with infiltrating uveitogenic T cells leads to rapid release of HMGB1 via the Fas/FasL inflammatory signaling pathway.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kentucky Lions Eye Center, University of Louisville, 301 E. Muhammad Ali Blvd., Louisville, KY, 40202, USA.
authors.forename: Guomin
authors.initials: G
authors.lastname: Jiang
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kentucky Lions Eye Center, University of Louisville, 301 E. Muhammad Ali Blvd., Louisville, KY, 40202, USA.|Department of Ophthalmology, Tangshan Gongren Hospital, Tangshan, Hebei, 063000, China.
authors.forename: Yunsong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kentucky Lions Eye Center, University of Louisville, 301 E. Muhammad Ali Blvd., Louisville, KY, 40202, USA.|Department of Pharmaceutical Sciences, Sullivan University College of Pharmacy, Louisville, KY, 40205, USA.
authors.forename: Juan
authors.initials: J
authors.lastname: Yun
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kentucky Lions Eye Center, University of Louisville, 301 E. Muhammad Ali Blvd., Louisville, KY, 40202, USA.
authors.forename: Amir Reza
authors.initials: AR
authors.lastname: Hajrasouliha
authors.affiliation: Department of Pharmaceutical Sciences, Sullivan University College of Pharmacy, Louisville, KY, 40205, USA.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Doheny Eye Institute, Los Angeles, CA, 90033, USA.
authors.forename: Deming
authors.initials: D
authors.lastname: Sun
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kentucky Lions Eye Center, University of Louisville, 301 E. Muhammad Ali Blvd., Louisville, KY, 40202, USA.
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Kaplan
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kentucky Lions Eye Center, University of Louisville, 301 E. Muhammad Ali Blvd., Louisville, KY, 40202, USA. h0shao01@louisville.edu.
authors.forename: Hui
authors.initials: H
authors.lastname: Shao
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology; D002450:Cell Communication / Q000276:immunology*; D018920:Coculture Techniques; D004195:Disease Models, Animal; D053222:Fas Ligand Protein / Q000276:immunology / Q000378:metabolism*; D005434:Flow Cytometry; D024243:HMGB1 Protein / Q000096:biosynthesis* / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D012165:Retinal Ganglion Cells / Q000276:immunology / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology*; D014605:Uveitis / Q000276:immunology / Q000378:metabolism*; D019014:fas Receptor / Q000276:immunology / Q000378:metabolism
chemical_list: D053222:Fas Ligand Protein; C491899:Fas protein, mouse; D024243:HMGB1 Protein; C582808:HMGB1 protein, mouse; D019014:fas Receptor