Profiling calcium signals of in vitro polarized human effector CD4(+) T cells

摘要

Differentiation of naive CD4(+) T cells into effector subtypes with distinct cytokine profiles and physiological roles is a tightly regulated process, the imbalance of which can lead to an inadequate immune response or auto immune disease. The crucial role of Ca2+ signals, mainly mediated by the store operated Ca2+ entry (SOCE) in shaping the immune response is well described. However, it is unclear if human effector CD4(+) T cell subsets show differential Ca2+ signatures in response to different stimulation methods. Herein, we provide optimized in vitro culture conditions for polarization of human CD4(+) effector T cells and characterize their SOCE following both pharmacological store depletion and direct T-cell receptor (TCR) activation. Moreover, we measured whole cell Ca2+ release activated Ca2+ currents (I-CRAC) and investigated whether the observed differences correlate to the expression of CRAC genes. Our results show that Ca2+ profiles of helper CD4(+) Th1, Th2 and Th17 are distinct and in part shaped by the intensity of stimulation. Regulatory T cells (Treg) are unique being the subtype with the most prominent SOCE response. Analysis of in vivo differentiated Treg unraveled the role of differential expression of ORAI2 in fine-tuning signals in Treg vs. conventional CD4(+) T cells.