Tregs expanded in vivo by TNFRSF25 agonists promote cardiac allograft survival.
BACKGROUND
Thymic-derived Foxp3(+)CD4(+) regulatory T cells (Tregs)-also called natural Tregs-are critical for the induction and maintenance of transplantation tolerance. Using an agonistic tumor necrosis factor-receptor super family (TNFRSF) 25 antibody, clone 4C12, we showed that TNFRSF25 is a powerful regulator of Treg proliferation-mediating expansion of natural Tregs in vivo. In the present study, we investigate the role of Tregs expanded in vivo by TNFRSF25 on cardiac allograft survival in a mouse model of fully major histocompatibility complex-mismatched ectopic heart transplants.


METHODS
C57BL/6 mice were treated with 20 μg of TNFRSF25 agonist 4C12 4 days before heterotopic allogeneic heart transplantation. The survival of the graft was monitored daily by abdominal palpation until the cessation of cardiac contraction. The severity of immune rejection was evaluated by histopathology. Infiltration of inflammatory cells and Tregs into the graft were characterized by flow cytometry. The expression of cytokines and other regulatory proteins was measured by quantitative real-time polymerase chain reaction.


RESULTS
Treatment with 4C12 resulted in expansion of Tregs to 30%-35% of CD4(+) cells and was associated with a significant prolongation of median graft survival from 8 days to 17 days (P=0.0049). On day 7 after transplantation, the time point when controls reject the graft, the transplants of 4C12-treated animals beat strongly and showed increased accumulation of Foxp3(+) Tregs within the graft and decreased infiltration of inflammatory cells.


CONCLUSIONS
TNFRSF25 agonists expand Tregs in vivo and delay allograft rejection.
Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101, USA.
Dietlinde
D
Wolf
Taylor H
TH
Schreiber
Panagiotis
P
Tryphonopoulos
Sen
S
Li
Andreas G
AG
Tzakis
Phillip
P
Ruiz
Eckhard R
ER
Podack
D000818:Animals; D000906:Antibodies / Q000494:pharmacology*; D015415:Biomarkers / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism; D006084:Graft Rejection / Q000235:genetics / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D006085:Graft Survival / Q000187:drug effects*; D016027:Heart Transplantation / Q000276:immunology*; D006648:Histocompatibility; D008285:Major Histocompatibility Complex / Q000276:immunology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D060888:Real-Time Polymerase Chain Reaction; D053219:Receptors, Tumor Necrosis Factor, Member 25 / Q000819:agonists* / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects* / Q000276:immunology; D013997:Time Factors
D000906:Antibodies; D015415:Biomarkers; D016207:Cytokines; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D053219:Receptors, Tumor Necrosis Factor, Member 25; C506034:Tnfrsf25 protein, mouse