Intracellular free zinc up-regulates IFN-γ and T-bet essential for Th1 differentiation in Con-A stimulated HUT-78 cells

• Published in: Biochemical and biophysical research communications 2011-04, Vol.407 (4), p.703-707
• Main Authors: Bao, Bin, Prasad, Ananda S., Beck, Frances W.J., Bao, Ginny W., Singh, Tapinder, Ali, Shadan, Sarkar, Fazlul H.
• Format: Article
• Language: English
• Subjects: Cell Differentiation - drug effects; Cell Differentiation - genetics; Cell Line; Concanavalin A - pharmacology; Humans; IFN-γ; IL-12Rβ2; Interferon-gamma - biosynthesis; Interferon-gamma - genetics; Receptors, Interleukin-12 - biosynthesis; Receptors, Interleukin-12 - genetics; T-bet; T-Box Domain Proteins - biosynthesis; T-Box Domain Proteins - genetics; Th1 Cells - cytology; Th1 Cells - immunology; Up-Regulation; Zinc; Zinc - deficiency; Zinc - metabolism; Zinc - pharmacology
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2011.03.084

► Zinc deficiency impairs cell-mediated immunity in humans. ► We find zinc increases the expression of IL-2, IFN-γ, IL-12Rβ2, and T-bet, essential for Th1-cell differentiation in Th0 cells. ► Zinc-specific chelator, TPEN, decreases the mRNA expression of IFN-γ and T-bet in Con-A-stimulated cells. ► High level of zinc increases intracellular free zinc in Con-A-stimulated cells. ► We hypothesize that free zinc is a molecular signal involved in expression of cytokines and transcription factors. Zinc deficiency impairs cellular immunity. Up-regulation of mRNA levels of IFN-γ, IL-12Rβ2, and T-bet are essential for Th1 differentiation. We hypothesized that zinc increases Th1 differentiation via up-regulation of IFN-γ and T-bet expression. To test this hypothesis, we used zinc-deficient and zinc-sufficient HUT-78 cells (a Th0 cell line) under different condition of stimulation in this study. We also used TPEN, a zinc-specific chelator, to decrease the bioavailability of zinc in the cells. We measured intracellular free zinc, cytokines, and the mRNAs of T-bet, IFN-γ, and IL-12Rβ2. In this study, we show that in zinc-sufficient HUT-78 cells, mRNA levels of IFN-γ, IL-12Rβ2, and T-bet in PMA/PHA-stimulated cells were increased in comparison to zinc-deficient cells. Although intracellular free zinc was increased slightly in PMA/PHA-stimulated cells, Con-A-stimulated cells in 5μM zinc medium showed a greater sustained increase in intracellular free zinc in comparison to cells incubated in 1μM zinc. The cells pre-incubated with TPEN showed decreased mRNA levels of IFN-γ and T-bet mRNAs in comparison to cells without TPEN incubation. We conclude that stimulation of cells by Con-A via TCR, release intracellular free zinc which functions as a signal molecule for generation of IFN-γ and T-bet, and IL-12Rβ2 mRNAs required for Th1 cell differentiation. These results suggest that zinc increase Th1 cell differentiation by up-regulation of IFN-γ and T-bet, and IL-12Rbβ2 mRNAs.