TY - JOUR
T1 - Interleukin-21 is a critical regulator of CD4 and CD8 T cell survival during priming under interleukin-2 deprivation conditions
AU - Khattar, Mithun
AU - Miyahara, Yoshihiro
AU - Schroder, Paul M.
AU - Xie, Aini
AU - Chen, Wenhao
AU - Stepkowski, Stanislaw M.
N1 - Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 2014/1/9
Y1 - 2014/1/9
N2 - Optimal T cell activation and expansion require binding of the common gamma-chain (cc) cytokine Interleukin-2 (IL-2) to its cognate receptor that in turn engages a γc/Janus tyrosine kinase (Jak)3 signaling pathway. Because of its restricted expression by antigen-activated T cells and its obligatory role in promoting their survival and proliferation, IL-2 has been considered as a selective therapeutic target for preventing T cell mediated diseases. However, in order to further explore IL-2 targeted therapy, it is critical to precisely understand its role during early events of T cell activation. In this study, we delineate the role of IL-2 and other γc cytokines in promoting the survival of CD4 and CD8 T cells during early phases of priming. Under IL-2 inhibitory conditions (by neutralizing anti-IL-2 mAbs), the survival of activated CD8+ T cells was reduced, whereas CD4+ T cells remained much more resistant. These results correlated with reduced Bcl-2 expression, and mitochondrial membrane potential in CD8+ T cells in comparison to CD4+ T cells. However, using transwell co-culture assays we have found that CD4+ T cells could rescue the survival of CD8+ T cells even under IL-2 deprived conditions via secretion of soluble factors. A cytokine screen performed on CD8+ T cells cultured alone revealed that IL-21, another cc cytokine, was capable of rescuing their survival under IL-2 deprivation. Indeed, blocking the IL-21 signaling pathway along with IL-2 neutralization resulted in significantly reduced survival of both CD4+ and CD8+ T cells. Taken together, we have shown that under IL-2 deprivation conditions, IL-21 may act as the major survival factor promoting T cell immune responses. Thus, investigation of IL-2 targeted therapies may need to be revisited to consider blockade of the IL-21 signaling pathways as an adjunct to provide more effective control of T cell immune responses.
AB - Optimal T cell activation and expansion require binding of the common gamma-chain (cc) cytokine Interleukin-2 (IL-2) to its cognate receptor that in turn engages a γc/Janus tyrosine kinase (Jak)3 signaling pathway. Because of its restricted expression by antigen-activated T cells and its obligatory role in promoting their survival and proliferation, IL-2 has been considered as a selective therapeutic target for preventing T cell mediated diseases. However, in order to further explore IL-2 targeted therapy, it is critical to precisely understand its role during early events of T cell activation. In this study, we delineate the role of IL-2 and other γc cytokines in promoting the survival of CD4 and CD8 T cells during early phases of priming. Under IL-2 inhibitory conditions (by neutralizing anti-IL-2 mAbs), the survival of activated CD8+ T cells was reduced, whereas CD4+ T cells remained much more resistant. These results correlated with reduced Bcl-2 expression, and mitochondrial membrane potential in CD8+ T cells in comparison to CD4+ T cells. However, using transwell co-culture assays we have found that CD4+ T cells could rescue the survival of CD8+ T cells even under IL-2 deprived conditions via secretion of soluble factors. A cytokine screen performed on CD8+ T cells cultured alone revealed that IL-21, another cc cytokine, was capable of rescuing their survival under IL-2 deprivation. Indeed, blocking the IL-21 signaling pathway along with IL-2 neutralization resulted in significantly reduced survival of both CD4+ and CD8+ T cells. Taken together, we have shown that under IL-2 deprivation conditions, IL-21 may act as the major survival factor promoting T cell immune responses. Thus, investigation of IL-2 targeted therapies may need to be revisited to consider blockade of the IL-21 signaling pathways as an adjunct to provide more effective control of T cell immune responses.
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U2 - 10.1371/journal.pone.0085882
DO - 10.1371/journal.pone.0085882
M3 - Article
C2 - 24416451
AN - SCOPUS:84897407676
SN - 1932-6203
VL - 9
JO - PLoS ONE
JF - PLoS ONE
IS - 1
M1 - e85882
ER -