title: Inducible co-stimulator (ICOS) is upregulated in experimental autoimmune uveoretinitis.
abstract: OBJECTIVE
  To study the expression of inducible co-stimulator (ICOS) and its association with T cell effector function in experimental autoimmune uveoretinitis (EAU).
  
  
  METHODS
  Eighteen Lewis rats were immunized by retinal S-antigen (50 microg) emulsified in complete Freund's adjuvant (CFA). Twelve normal rats served as normal controls and 18 receiving injection of CFA and PBS as CFA controls for studying the influence of CFA on the expression of ICOS in CD4+CD25+ T cells. ICOS expression on cells from the spleens, inguinal nodes and retinae on day 0 (normal rats), 7, 13 and 21 was investigated using fluorescent quantitative real-time-PCR and Western blot. Expression of B7RP-1, an ICOS ligand, was also studied by Western blot. The phenotype of the cells from the aforementioned three tissues was identified with flow cytometry using antibodies to ICOS, CD4 and CD25. ICOS+ cells from the lymph nodes, and spleens on day 13 were magnetically sorted and cultured with S-antigen to study the cytokines production with enzyme-linked immunosorbent assay.
  
  
  RESULTS
  An obvious uveitis was induced in all the immunized rats on day 13 after S-antigen immunization. The mRNA and protein of ICOS were scarcely detectable in normal rat spleens. In EAU rats, an up-regulation of ICOS could be observed on day 7 and was very pronounced on day 13, followed by a decrease on day 21 in the spleens, draining nodes and retinae. Similarly, B7RP-1 expression seemed to be up-regulated during EAU. Flow cytometry showed that ICOS+ cells were mostly CD4 positive. Kinetics of ICOS+CD4+CD25+ T cells was similar to that of ICOS+ cells. CFA alone was also able to induce increased expression of ICOS in CD4+CD25+ T cells. IFN-gamma was secreted predominantly by ICOS+ T cells.
  
  
  CONCLUSIONS
  ICOS expression is up-regulated in association with T cell effector capacity in EAU. It is presumed that the ICOS/B7RP-1 costimulatory pathway may play a role in the development of EAU.
authors.affiliation: Zhongshan Ophthalmic Center, Sun Yat-sen University, Xianlie Road 54, Guangzhou, 510060, People's Republic of China.
authors.forename: Lin
authors.initials: L
authors.lastname: Xing
authors.forename: Peizeng
authors.initials: P
authors.lastname: Yang
authors.forename: Changyou
authors.initials: C
authors.lastname: Wu
authors.forename: HaoLi
authors.initials: H
authors.lastname: Jin
authors.forename: Xuan
authors.initials: X
authors.lastname: Chen
authors.forename: Yang
authors.initials: Y
authors.lastname: Gao
authors.forename: Bing
authors.initials: B
authors.lastname: Li
authors.forename: Xiangkun
authors.initials: X
authors.lastname: Huang
authors.forename: Hongyan
authors.initials: H
authors.lastname: Zhou
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics / Q000378:metabolism*; D019393:Arrestin; D001327:Autoimmune Diseases / Q000378:metabolism*; D018122:B7-1 Antigen / Q000378:metabolism; D015153:Blotting, Western; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D060945:Inducible T-Cell Co-Stimulator Ligand; D060889:Inducible T-Cell Co-Stimulator Protein; D008024:Ligands; D008198:Lymph Nodes / Q000166:cytology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D012160:Retina / Q000166:cytology; D012173:Retinitis / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013154:Spleen / Q000166:cytology; D018417:Th1 Cells / Q000378:metabolism*; D015854:Up-Regulation; D014605:Uveitis / Q000378:metabolism*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D019393:Arrestin; D018122:B7-1 Antigen; C556695:Icos protein, rat; D060945:Inducible T-Cell Co-Stimulator Ligand; D060889:Inducible T-Cell Co-Stimulator Protein; D008024:Ligands; D012333:RNA, Messenger