GITR engagement preferentially enhances proliferation of functionally competent CD4+CD25+FoxP3+ regulatory T cells.
Naturally occurring regulatory T cells (Treg) express high levels of glucocorticoid-induced tumour necrosis factor receptor (GITR). However, studies of the role of GITR in Treg biology has been complicated by the observation that upon activation effector CD4(+) T (Teff) cells also express the receptor. Here, we dissect the contribution of GITR-induced signaling networks in the expansion and function of FoxP3(+) Treg. We demonstrate that a high-affinity soluble Fc-GITR-L dimer, in conjugation with alphaCD3, specifically enhances in vitro proliferation of Treg, which retain their phenotypic markers (CD25 and FoxP3) and their suppressor function, while minimally affecting Teff cells. Furthermore, Fc-GITR-L does not impair Teff susceptibility to suppression, as judged by cocultures employing GITR-deficient and GITR-sufficient CD4(+) T-cell subsets. Notably, this expansion of Treg could also be seen in vivo, by injecting FoxP3-IRES-GFP mice with Fc-GITR-L even in the absence of antigenic stimulation. In order to test the efficacy of these findings therapeutically, we made use of a C3H/HeJ hemophilia B-prone mouse model. The use of liver-targeted human coagulation factor IX (hF.IX) gene therapy in this model has been shown to induce liver toxicity and the subsequent failure of hF.IX expression. Interestingly, injection of Fc-GITR-L into the hemophilia-prone mice that were undergoing liver-targeted hF.IX gene therapy increased the expression of F.IX and reduced the anticoagulation factors. We conclude that GITR engagement enhances Treg proliferation both in vitro and in vivo and that Fc-GITR-L may be a useful tool for in vivo tolerance induction.
Division of Immunology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA. gliao@bidmc.harvard.edu
Gongxian
G
Liao
Sushrusha
S
Nayak
Jose R
JR
Regueiro
Scott B
SB
Berger
Cynthia
C
Detre
Xavier
X
Romero
Rene
R
de Waal Malefyt
Talal A
TA
Chatila
Roland W
RW
Herzog
Cox
C
Terhorst
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002460:Cell Line; D049109:Cell Proliferation; D004195:Disease Models, Animal; D005164:Factor IX / Q000235:genetics; D051858:Forkhead Transcription Factors / Q000378:metabolism; D015316:Genetic Therapy; D053450:Glucocorticoid-Induced TNFR-Related Protein; D002836:Hemophilia B / Q000628:therapy; D006801:Humans; D007108:Immune Tolerance; D007141:Immunoglobulin Fc Fragments / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism; D008024:Ligands; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017475:Receptors, Nerve Growth Factor / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D053450:Glucocorticoid-Induced TNFR-Related Protein; C508018:Il2ra protein, mouse; D007141:Immunoglobulin Fc Fragments; D053645:Interleukin-2 Receptor alpha Subunit; D008024:Ligands; D017475:Receptors, Nerve Growth Factor; D018124:Receptors, Tumor Necrosis Factor; D011993:Recombinant Fusion Proteins; C106544:Tnfrsf18 protein, mouse; D005164:Factor IX