Polarization of macrophages to M1 or M2 cells is important for mounting responses against bacterial and helminth infections, respectively. Jumonji domain containing-3 (Jmjd3), a histone 3 Lys27 (H3K27) demethylase, has been implicated in the activation of macrophages. Here we show that Jmjd3 is essential for M2 macrophage polarization in response to helminth infection and chitin, though Jmjd3 is dispensable for M1 responses. Furthermore, Jmjd3 (also known as Kdm6b) is essential for proper bone marrow macrophage differentiation, and this function depends on demethylase activity of Jmjd3. Jmjd3 deficiency affected trimethylation of H3K27 in only a limited number of genes. Among them, we identified Irf4 as encoding a key transcription factor that controls M2 macrophage polarization. Collectively, these results show that Jmjd3-mediated H3K27 demethylation is crucial for regulating M2 macrophage development leading to anti-helminth host responses.

Basophils express major histocompatibility complex class II, CD80 and CD86 and produce interleukin 4 (IL-4) in various conditions. Here we show that when incubated with IL-3 and antigen or complexes of antigen and immunoglobulin E (IgE), basophils internalized, processed and presented antigen as complexes of peptide and major histocompatibility complex class II and produced IL-4. Intravenous administration of ovalbumin-pulsed basophils into naive mice 'preferentially' induced the development of naive ovalbumin-specific CD4+ T cells into T helper type 2 (T(H)2) cells. Mice immunized in this way, when challenged by intravenous administration of ovalbumin, promptly produced ovalbumin-specific IgG1 and IgE. Finally, intravenous administration of IgE complexes rapidly induced T(H)2 cells only in the presence of endogenous basophils, which suggests that basophils are potent antigen-presenting cells that 'preferentially' augment T(H)2-IgE responses by capturing IgE complex.

Systemic administration of IL-18 induces polyclonal IgE responses by causing NKT cells to express CD40 ligand and to produce IL-4. Administration of IL-33 also induces IgE response, although the mechanism underlying IgE response is unclear. Here, we compared the effects of IL-18 and IL-33 on bone marrow-derived mast cells and basophils as well as non-polarized and T(h)2-polarized CD4(+) T cells in vitro. Basophils, comprising IL-18Ralpha(+) cells (14.2%) and IL-33Ralpha(+) cells (34.6%), and mast cells, comprising IL-18Ralpha(+) cells (2.0%) and IL-33Ralpha(+) cells (95.6%), produce IL-4, IL-6, IL-13, granulocyte macrophage colony-stimulating factor (GM-CSF) and chemokines (RANTES, MIP-1alpha, MIP-1beta and MCP-1), upon stimulation with IL-18 and/or IL-33 in the presence of IL-3. Only basophils strongly produce IL-4. Furthermore, compared with mast cells, basophils produce larger amounts of the above cytokines and chemokines in response to IL-33. Level of IL-33Rbeta-mRNA expression in basophils is higher than that in mast cells. Effect of IL-33 is dependent on ST2 binding, and its signal is transduced via MyD88 in vitro. We also found that IL-2 plus IL-18 or IL-33 alone stimulates non-polarized or T(h)2-polarized CD4(+) T cells to produce IL-4 and IL-13 or IL-5 and IL-13, respectively. We finally showed that administration of IL-33 into mice ST2/MyD88 dependently induces airway hyperresponsiveness (AHR) and goblet cell hyperplasia by induction of IL-4, IL-5 and IL-13 in the lungs. Furthermore, same treatment of RAG-2(-/-) mice, lacking T and B cells, more strikingly induced AHR with marked goblet cell hyperplasia and eosinophilic infiltration in the lungs. Thus, IL-33 induces asthma-like symptom entirely independent of acquired immune system.

Transgenic mice expressing the mouse interleukin 33 (IL-33) gene driven by a keratin 14 promoter were generated. The skin-selective expression of the IL-33 gene was enhanced, and intense immunofluorescence for IL-33 was evident in the nuclei of the epidermis. Spontaneous itchy dermatitis developed in those mice at 6-8 wk of age in specific pathogen-free conditions. In the lesional skin, the epidermis was thickened and the eosinophils were infiltrated with increased expression of the eosinophil peroxidase and major basic protein genes. Mast cells were also abundant there, and blood histamine and total IgE levels were high. Those phenotypes closely resemble the features of atopic dermatitis. In peripheral blood and lesional skin, IL-5, IL-13, regulated upon activation, normally Texpressed, and presumably secreted (RANTES)/CCL5, and Eotaxin 1/CCL11 were increased, whereas TNF-α, IFN-γ, and thymic stromal lymphopoietin (TSLP) were unaltered. Furthermore, the proportion of group 2 innate lymphoid cells (ILC2s), which produce IL-5, were significantly increased in the lesional skin, peripheral blood, and regional lymph nodes. The dermatitis with eosinophil infiltration was improved by the administration of an anti-IL-5 antibody. These results suggest that the expression of IL-33 in the skin activates an immune response involving ILC2 and that this process might play a crucial role in the pathogenesis of allergic inflammation that is characteristic of atopic dermatitis.Atopy | natural helper cells | nuocytes

Interleukin (IL)-18 was originally discovered as a factor that enhanced IFN-γ production from anti-CD3-stimulated Th1 cells, especially in the presence of IL-12. Upon stimulation with Ag plus IL-12, naïve T cells develop into IL-18 receptor (IL-18R) expressing Th1 cells, which increase IFN-γ production in response to IL-18 stimulation. Therefore, IL-12 is a commitment factor that induces the development of Th1 cells. In contrast, IL-18 is a proinflammatory cytokine that facilitates type 1 responses. However, IL-18 without IL-12 but with IL-2, stimulates NK cells, CD4+ NKT cells, and established Th1 cells, to produce IL-3, IL-9, and IL-13. Furthermore, together with IL-3, IL-18 stimulates mast cells and basophils to produce IL-4, IL-13, and chemical mediators such as histamine. Therefore, IL-18 is a cytokine that stimulates various cell types and has pleiotropic functions. IL-18 is a member of the IL-1 family of cytokines. IL-18 demonstrates a unique function by binding to a specific receptor expressed on various types of cells. In this review article, we will focus on the unique features of IL-18 in health and disease in experimental animals and humans.