OBJECTIVE: We sought to determine whether non-T-cell-derived IL-4 acts on skin-derived DCs to promote the TH2 response to cutaneously encountered antigen and allergic skin inflammation.
METHODS: DCs from dLNs of ovalbumin (OVA)-exposed skin were analyzed by flow cytometry and for their ability to polarize OVA-specific naive CD4+ T cells. Skin inflammation following epicutaneous sensitization of tape-stripped skin was assessed by flow cytometry of skin cells and real-time quantitative PCR of cytokines. Cytokine secretion and antibody levels were evaluated by ELISA.
RESULTS: Scratching upregulated IL4 expression in human skin. Similarly, tape stripping caused rapid basophil-dependent upregulation of cutaneous Il4 expression in mouse skin. In vitro treatment of DCs from skin dLNs with IL-4 promoted their capacity to drive TH2 differentiation. DCs from dLNs of OVA-sensitized skin of Il4-/- mice and CD11c-CreIl4rflox/- mice, which lack IL-4Rα expression in DCs (DCΔ/Δll4ra mice), were impaired in their capacity to drive TH2 polarization compared with DCs from controls. Importantly, OVA-sensitized DCΔ/Δll4ra mice demonstrated impaired allergic skin inflammation and OVA-specific systemic TH2 response evidenced by reduced TH2 cytokine secretion by OVA-stimulated splenocytes and lower levels of OVA-specific IgE and IgG1 antibodies, compared with controls.
CONCLUSIONS: Mechanical skin injury causes basophil-dependent upregulation of cutaneous IL-4. IL-4 acts on skin DCs that capture antigen and migrate to dLNs to promote their capacity for TH2 polarization and drive allergic skin inflammation.
目的:确定非T细胞来源的IL-4是否作用于皮肤来源的DC以促进Th2对皮肤遇到的抗原和过敏性皮肤炎症的应答。
方法:通过流式细胞术分析来自卵白蛋白(OVA)暴露的皮肤的dLN的DC及其极化OVA特异性初始CD4+T细胞的能力。通过皮肤细胞的流式细胞术和细胞因子的qRT-PCR评估胶带剥离皮肤的表皮(EC)致敏后的皮肤炎症。通过ELISA评估细胞因子分泌和抗体水平。
结果:抓挠上调人皮肤中IL4的表达。同样,胶带剥离导致小鼠皮肤中皮肤Il4表达的快速嗜碱性粒细胞依赖性上调。用IL-4体外处理来自皮肤dLN的DC促进其驱动Th2分化的能力。来自Il4-/-小鼠的OVA致敏皮肤的dLN的DC和在DC(DCΔ/Δll4ra小鼠)中缺乏IL-4Rα表达的CD11cCreIl4rflox/-小鼠的dLN的驱动Th2极化的能力与来自对照的DC相比受损。重要的是,OVA致敏的DCΔ/Δll4ra小鼠表现出受损的过敏性皮肤炎症和OVA特异性全身性Th2反应,这通过OVA刺激的脾细胞减少的Th2细胞因子分泌和较低水平的OVA特异性IgE和IgG1抗体来证明,与对照组相比。
结论:机械皮肤损伤导致皮肤IL-4的嗜碱性粒细胞依赖性上调。IL-4作用于捕获抗原并迁移至dLN的皮肤DC以促进其Th2极化能力并驱动过敏性皮肤炎症。