title: Ex vivo expansion of CD4+CD25+FoxP3+ T regulatory cells based on synergy between IL-2 and 4-1BB signaling.
abstract: Naturally occurring CD4(+)CD25(+)FoxP3(+) T regulatory (Treg) cells require three distinct signals transduced via TCR, CD28, and IL-2R for their development and maintenance. These requirements served as the basis for several recently developed ex vivo expansion protocols that relied on the use of solid support-bound Abs to CD3 and CD28 in the presence of high dose IL-2. We report in this study that Treg cells up-regulate the expression of inducible costimulatory receptor 4-1BB in response to IL-2, and stimulation using this receptor via a novel form of 4-1BB ligand (4-1BBL) fused to a modified form of core streptavidin (SA-4-1BBL) was effective in expanding these cells up to 110-fold within 3 wk. Expanded cells up-regulated CD25, 4-1BB, and membranous TGF-beta, suppressed T cell proliferation, and prevented the rejection of allogeneic islets upon adoptive transfer into graft recipients. Importantly, SA-4-1BBL rendered CD4(+)CD25(-) T effector cells refractive to suppression by Treg cells. This dual function of signaling via 4-1BB, vis-à-vis Treg cell expansion and licensing T effector cells resistant to Treg cell suppression, as well as the up-regulation of 4-1BB by IL-2 may serve as important regulatory mechanisms for immune homeostasis following antigenic challenge. Stimulation using a soluble form of SA-4-1BBL represents a novel approach to expand Treg cells with potential therapeutic applications in autoimmunity and transplantation.
authors.affiliation: Institute for Cellular Therapeutics, and Department of Microbiology and Immunology, University of Louisville, Louisville, KY 40202, USA.
authors.forename: Kutlu G
authors.initials: KG
authors.lastname: Elpek
authors.forename: Esma S
authors.initials: ES
authors.lastname: Yolcu
authors.forename: Deanna D H
authors.initials: DD
authors.lastname: Franke
authors.forename: Chantale
authors.initials: C
authors.lastname: Lacelle
authors.forename: Rich-Henry
authors.initials: RH
authors.lastname: Schabowsky
authors.forename: Haval
authors.initials: H
authors.lastname: Shirwan
mesh_terms: D053330:4-1BB Ligand / Q000494:pharmacology; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004195:Disease Models, Animal; D051858:Forkhead Transcription Factors / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics; D020869:Gene Expression Profiling; D006084:Graft Rejection / Q000517:prevention & control; D007376:Interleukin-2 / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000276:immunology; D016381:Islets of Langerhans Transplantation; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010641:Phenotype; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000276:immunology*; D019809:Streptavidin / Q000494:pharmacology; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000276:immunology*; D016212:Transforming Growth Factor beta / Q000187:drug effects / Q000276:immunology; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9 / Q000096:biosynthesis / Q000187:drug effects* / Q000276:immunology*; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology
chemical_list: D053330:4-1BB Ligand; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D007376:Interleukin-2; D016212:Transforming Growth Factor beta; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9; D019809:Streptavidin