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Activation-inducible TNFR family receptor (AITR) signaling mediates the polarization of CD4+ T cells into Th1, Th2, and Th17, converts Treg to Teff and eradicates solid tumors
Presenter/Authors
Byoung S. Kwon, Seung J. Lee, Young H. Kim, Joong W. Lee, Sun H. Hwang, Dass S. Vinay. Eutilex Co.,Ltd., Seoul, Korea, Republic of
Disclosures
B.S. Kwon: ; Eutilex, Co., Ltd. S.J. Lee: ; Eutilex, Co., Ltd. Y.H. Kim: ; Eutilex, Co., Ltd. J.W. Lee: ; Eutilex, Co., Ltd. S.H. Hwang: ; Eutilex, Co., Ltd.. D.S. Vinay: None.
Abstract
AITR (activation-inducible TNFR family receptor, human GITR), an inducible costimulatory receptor of human T cells, is expressed constitutively on Treg and inducible on Teff upon antigen engagement. AITR co-stimulates T cell activation and recruits certain members of TRAF family upon interaction with its ligand. We examined whether the stimulation of distinct regions of extracellular domain of AITR can generate signals that promote different subsets of CD4+ T cells. We found that crosslinking AITR by agonistic anti-AITR Abs (A27, A41, and A35), that recognize three distinct regions of the extracellular domain, polarize CD4+ T cells into Th1, Th2 and Th17, respectively. The subset polarization evoked by these antibodies was the result of recruitment of specific TRAFs, phosphorylation of distinct STATs and expression of Th subset fate-determining master regulatory genes. Stimulation with A27 recruited TRAF-1 and -2, activated STAT-1, -4 and JNK1/2, and induced transcription factor T-bet. On the other hand, activation with A35 recruited TRAF-6, activated STAT-3 and p38 MAPK, and induced RORγt. In contrast, A41 recruited TRAF-3 and -5, activated STAT-5, -6 and ERK1/2, and produced GATA-3. Remarkably, A27 induced the conversion of CD25+Foxp3+ Treg cells to IFN-γ-producing Th1 cells with a concomitant suppression of Foxp3 and TGF-β expression both in healthy individuals as well as cancer patients. A35 also, but not A41, suppressed the expression of Foxp3 and induced IL-17 in Treg cells. A27 alone, but not others produced a strong anti-tumor effect in a human tumor xenograft model of humanized mice in an IFN-γ- and Treg conversion-dependent mechanism. Taken together, the data that AITR regulates Th subset polarization and eradicates solid tumors can be a target for broad-spectrum immune check point therapeutics against cancers and autoimmune diseases. |