IL-4 synergistically enhances both IL-2– and IL-12–induced IFN-γ expression in murine NK cells

Abstract

Interleukin-4 (IL-4) is thought to influence T and natural killer (NK) cells by down-regulating T helper 1 (Th1)–type cytokines like interferon-γ (IFN-γ). While investigating IL-4 regulation of IFN-γ expression, we found that IL-4 synergized with IL-2 or IL-12 to enhance IFN-γ production and mRNA expression in spleen-derived, IL-2–cultured NK cells, as well as negatively sorted fresh DX5+/CD3- NK cells albeit at lower levels. The positive effect of IL-4 on IL-2–induced IFN-γ production was dependent upon signal transducer and activator of transcription 6 (Stat6) because this response was virtually abrogated in Stat6-/- mice. Notably, though, IL-12 plus IL-4 synergy on IFN-γ expression was intact in Stat6-/- mice. In exploring possible molecular mechanisms to account for the synergistic effects of IL-4 on murine NK cells, we found that IL-2 plus IL-4 stimulation resulted in a modest increase in tyrosine phosphorylation of Stat5, while IL-12 plus IL-4 treatment resulted in a more substantial increase in tyrosine-phosphorylated Stat4. Finally, to identify regions of the IFN-γ promoter that may be involved, NK cells from human IFN-γ promoter/luciferase transgenic mice were treated with cytokines. NK cells from proximal (-110 to +64) promoter region mice did not respond to cytokine stimulation; however, the intact -565 to +64 IFN-γ promoter responded synergistically to IL-2 plus IL-4 and to IL-12 plus IL-4 in NK cells. These data demonstrate a role for IL-4 in enhancing IFN-γ expression in murine NK cells that is partially dependent on Stat6 in IL-2 costimulation and completely independent of Stat6 in IL-12 costimulations. (Blood. 2003;102:207-214)

Murine Plasmacytoid Dendritic Cells Produce IFN-γ upon IL-4 Stimulation

“…4C). In contrast, it has been demonstrated recently that IL-4 synergistically enhances IL-2-induced IFN-␥ production from NK cells, but IL-4 itself does not induce IFN-␥ production from NK cells (35). It has also been shown that although IL-4 enhances IL-12-induced IFN-␥ production from CD8 ϩ DCs, IL-4 itself does not induce IFN-␥ production from CD8 ϩ DCs (36).…”

A Distal Region in the Interferon-γ Gene Is a Site of Epigenetic Remodeling and Transcriptional Regulation by Interleukin-2

“…Furthermore, the tremendous synergy observed between IL-2 and IL-12 with respect to IFN-␥ expression is likely due, at least in part, to the cooperative activation of multiple transcriptional regulatory regions within the IFNG genomic DNA (such as Stat4 and Stat5 interactions). Although the synergy between IL-2 and IL-12 on IFN-␥ expression is dependent on Stat4 and independent of T-bet expression (25), the one or more precise mechanisms are still not clear. Further studies analyzing in vivo interactions of DNA binding proteins with specific regions of the IFNG gene as well as changes in chromatin conformation following stimulation will be required to more precisely define the epigenetic and transcriptional regulatory mechanisms of this gene.…”

“…Strong IFN-␥ mRNA expression in NK92 was evident at 3 h and was slightly diminished after 6 h of IL-2 treatment. Our group and others have also reported that co-treatment of activated T cells or NK cells with IL-2 and IL-12 leads to a highly synergistic effect on IFN-␥ expression (25,26). A time course experiment was performed on NK92 cells under IL-2, IL-12, and IL-2 plus IL-12 conditions to confirm these data (Fig.…”

Interleukin‐4 supports interleukin‐12‐induced proliferation and interferon‐γ secretion in human activated lymphoblasts and T helper type 1 cells

“…26,27 In addition, IL-4 and IL-12 can co-operate in Th1, NK and dendritic cells in the murine system. 20,[28][29][30][31] This co-operation between Th cell cytokines might explain some of the paradoxical effects seen in several Th1-polarized mouse models of autoimmunity. 18 However, neither the mechanism responsible for synergy nor its role in the human system has been established for T cells to date.…”

“…30 Supporting this idea, enhanced signal transduction has recently been demonstrated for IL-4/IL-12 in murine NK cells. 31 One key signalling pathway downstream of cytokine receptors is the Janus kinase (JAK)/signal tranducer and activator of transcription (STAT) pathway. 32 Signal transduction through the IL-12 receptor-b1/b2 heterodimer induces phosphorylation of JAK2 and tyrosine kinase 2 (TYK2) as well as STAT1, STAT3, STAT4 and STAT5, 5,6,[33][34][35][36][37][38] which are also phosphorylated in Th1 cells after differentiation.…”