title: Transforming growth factor-β2 increases the capacity of retinal pigment epithelial cells to induce the generation of regulatory T cells.
abstract: The present study investigated the underlying mechanism of the induction of regulatory T cells (Tregs) by retinal pigment epithelial (RPE) cells and the characteristics of these Tregs. Human RPE cells were cultured in the presence or absence of transforming growth factor-β 2 (TGF-β2), and reverse-transcription quantitative PCR was performed to determine the mRNA expression of indoleamine 2,3-dioxygenase (IDO) and nuclear factor erythroid 2-related factor (Nrf2). Supernatants of RPE cell cultures were added to CD4+ T cells to induce Tregs. The RPE-induced Tregs were purified by two-step magnetic cell sorting. The natural Tregs were isolated from the peripheral blood mononuclear cells of healthy volunteers. Purified CD4+ CD25- T cells (2 x 10(5)/well) were cultured alone or with Tregs (various densities, natural or RPE-induced). The proliferation of CD4+ CD25- T cells was determined by 3H-thymidine incorporation. After 24 h of stimulation with TGF-β2, the mRNA expression of IDO in RPE cells was upregulated. The highest level of IDO mRNA expression was reached after 72 h of stimulation with TGF-β2. However, the Nrf2 mRNA expression was slightly decreased after 24 h of stimulation with TGF-β2 and significantly increased after 48-72 h of TGF-β2 stimulation. Increased levels of CD25 expression were observed on CD4+ T cells exposed to supernatants of RPE cell cultures treated with TGF-β2 and recombinant interleukin-2. The RPE-induced Tregs were more effective at suppressing the proliferation of CD4+ CD25- T cells compared with native Tregs. These findings suggested that IDO may be a signaling protein in RPE cells which is implicated in the induction of Tregs. RPE-induced Tregs have the potential to be applied for immunotherapy for ocular inflammatory diseases.
authors.affiliation: Department of Ophthalmology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu 210002, P.R. China.
authors.forename: Feng
authors.initials: F
authors.lastname: Yan
authors.affiliation: Department of Neurosurgical Laboratory, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu 210002, P.R. China.
authors.forename: Jin
authors.initials: J
authors.lastname: He
authors.affiliation: Department of Ophthalmology, No. 97 Hospital, Xuzhou, Jiangsu 221004, P.R. China.
authors.forename: Li
authors.initials: L
authors.lastname: Tang
authors.affiliation: Department of Ophthalmology, No. 97 Hospital, Xuzhou, Jiangsu 221004, P.R. China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Kong
authors.affiliation: Department of Ophthalmology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu 210002, P.R. China.
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Department of Ophthalmology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu 210002, P.R. China.
authors.forename: Suihua
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Ophthalmology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu 210002, P.R. China.
authors.forename: Zhenping
authors.initials: Z
authors.lastname: Huang
mesh_terms: D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002469:Cell Separation; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000235:genetics / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000166:cytology*; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000378:metabolism*; D053781:Transforming Growth Factor beta2 / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D012333:RNA, Messenger; D053781:Transforming Growth Factor beta2