title: Donor CD4+ Foxp3+ regulatory T cells are necessary for posttransplantation cyclophosphamide-mediated protection against GVHD in mice.
abstract: Posttransplantation cyclophosphamide (PTCy) is an effective prophylaxis against graft-versus-host disease (GVHD). However, it is unknown whether PTCy works singularly by eliminating alloreactive T cells via DNA alkylation or also by restoring the conventional (Tcon)/regulatory (Treg) T-cell balance. We studied the role of Tregs in PTCy-mediated GVHD prophylaxis in murine models of allogeneic blood or marrow transplantation (alloBMT). In 2 distinct MHC-matched alloBMT models, infusing Treg-depleted allografts abrogated the GVHD-prophylactic activity of PTCy. Using allografts in which Foxp3(+) Tregs could be selectively depleted in vivo, either pre- or post-PTCy ablation of donor thymus-derived Tregs (tTregs) abolished PTCy protection against GVHD. PTCy treatment was associated with relative preservation of donor Tregs. Experiments using combinations of Foxp3(-) Tcons and Foxp3(+) Tregs sorted from different Foxp3 reporter mice indicated that donor Treg persistence after PTCy treatment was predominantly caused by survival of functional tTregs that retained Treg-specific demethylation and also induction of peripherally derived Tregs. Finally, adoptive transfer of tTregs retrieved from PTCy-treated chimeras rescued PTCy-treated, Treg-depleted recipients from lethal GVHD. Our findings indicate that PTCy-mediated protection against GVHD is not singularly dependent on depletion of donor alloreactive T cells but also requires rapidly recovering donor Tregs to initiate and maintain alloimmune regulation.
authors.affiliation: Division of Hematologic Malignancies, Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD;
authors.forename: Sudipto
authors.initials: S
authors.lastname: Ganguly
authors.affiliation: Department of Microbiology and Immunology, Miller School of Medicine, University of Miami, Miami, FL; and.
authors.forename: Duncan B
authors.initials: DB
authors.lastname: Ross
authors.affiliation: Division of Blood and Marrow Transplantation, Department of Pediatrics, University of Minnesota Cancer Center, Minneapolis, MN.
authors.forename: Angela
authors.initials: A
authors.lastname: Panoskaltsis-Mortari
authors.affiliation: Division of Hematologic Malignancies, Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD;
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Kanakry
authors.affiliation: Division of Blood and Marrow Transplantation, Department of Pediatrics, University of Minnesota Cancer Center, Minneapolis, MN.
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Blazar
authors.affiliation: Department of Microbiology and Immunology, Miller School of Medicine, University of Miami, Miami, FL; and.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Levy
authors.affiliation: Division of Hematologic Malignancies, Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD;
authors.forename: Leo
authors.initials: L
authors.lastname: Luznik
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation / Q000009:adverse effects*; D018890:Chemoprevention; D003520:Cyclophosphamide / Q000008:administration & dosage / Q000494:pharmacology*; D019175:DNA Methylation; D004195:Disease Models, Animal; D051858:Forkhead Transcription Factors / Q000378:metabolism; D006086:Graft vs Host Disease / Q000235:genetics / Q000276:immunology* / Q000517:prevention & control*; D008221:Lymphoid Tissue / Q000187:drug effects / Q000276:immunology; D051379:Mice; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism; D014019:Tissue Donors; D018183:Transplantation Chimera; D014184:Transplantation, Homologous
chemical_list: D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D003520:Cyclophosphamide