Abstract：
BACKGROUND: Atopic dermatitis is characterized by scratching and a TH2-dominated local and systemic response to cutaneously encountered antigens. Dendritic cells (DCs) capture antigens in the skin and rapidly migrate to draining lymph nodes (dLNs) where they drive the differentiation of antigen-specific naive T cells.
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.
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.
摘要：
背景：特应性皮炎的特征在于抓挠和对皮肤遇到的抗原的Th2-主导的局部和全身反应。树突状细胞（DC）捕获皮肤中的抗原，并迅速迁移到引流淋巴结（dLN），在那里它们驱动抗原特异性初始T细胞的分化。
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。
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。
