Background: Dendritic cells (DCs) play an important role in host defense against pathogen infection. DC-specific intercellular adhesion molecule-3-grabbing nonintegrin (SIGN) is a group II C-type lectin receptor and specifically expressed on the surface of DCs. This study aimed to determine whether DC-SIGN affects intracellular signaling activation, Th1/Th2 imbalance and aspergillus immune evasion in aspergillus infection, and explore the application of DC-SIGN-modified DCs in immunotherapy.
Methods: DCs were first obtained from the mononuclear cells of peripheral blood. The interferon (IFN)-γ and dexamethasone (Dex) were used to stimulate DCs. The expression of DC-SIGN, Th1 and Th2 cytokines, and the capacity of DCs in stimulating T cells proliferation and phagocytosis, and nuclear factor (NF)-κB activation were analyzed. In addition, adenovirus expression vector Ad-DC-SIGN was generated to transfect DCs. Mannan was used to block DC-SIGN signaling for confirming the involvement of DC-SIGN function in Aspergillus fumigatus (Af)-induced DCs maturation. The unpaired, two-tailed Student's t-test was used in the comparisons between two groups.
Results: Exogenous IFN-γ could activate Af-induced DCs and promote the Th0 cells toward Th1 profile (interleukin [IL]-12 in IFN-γ/Af group: 50.96 ± 4.38 pg/ml; control/Af group: 29.70 ± 2.00 pg/ml, t = 10.815, P < 0.001). On the other hand, Dex inhibited the secretion of Th2 cytokines (IL-10 in Dex/Af group: 5.27 ± 0.85 pg/ml; control/Af group: 15.14 ± 1.40 pg/ml, t = 14.761, P < 0.001)), and successfully caused immunosuppression. After transfection with Ad-DC-SIGN, DCs have improved phagocytosis (phagocytosis rates in Ad-DC-SIGN group: 74.0% ± 3.4%; control group: 64.7% ± 6.8%, t = 3.104, P = 0.013). There was more Th1 cytokine secreted in the Af-induced DC-SIGN modified DCs (IL-12 in Ad-DC-SIGN/Af group: 471.98 ± 166.31 pg/ml; control/Af group: 33.35 ± 5.98 pg/ml, t = 6.456, P = 0.001), correlated to the enhanced NF-κB activation.
Conclusion: Overexpressing DC-SIGN in DCs had a protective function on aspergillosis.
树突状细胞表面DC-SIGN过表达对于曲霉感染起保护性作用 摘要 背景：树突状细胞（dendritic cells, DCs）在机体抗病原体感染中具有重要作用。DC-SIGN是主要表达于DCs表面的C型凝集素样受体中的一员。本研究旨在探讨DC-SIGN是否在曲霉感染中影响DCs细胞内信号传导、辅助T细胞Th1/Th2的平衡及曲霉菌免疫逃逸, 同时探索DC-SIGN基因修饰的树突状细胞用于免疫治疗的可能性。 方法：首先从外周血中提取了DCs。用IFN-γ和地塞米松分别刺激DCs后检测DC-SIGN的表达、Th1和Th2细胞因子分泌水平、DCs吞噬功能及刺激T细胞增殖能力、以及NF-κB的激活水平。此外，构建DC-SIGN腺病毒载体用于DCs转染。用甘露聚糖阻断DC-SIGN信号传导以明确DC-SIGN在烟曲霉刺激DCs成熟中的作用。未配对的双尾t检验用于组间比较。 结果：外源性IFN-γ刺激可以激活DCs并促使辅助T细胞向Th1细胞分化（IL-12水平在IFN-γ/Af 组为: 50.96±4.38pg/ml; 在control/Af组中为: 29.70±2.00 pg/ml, t = 10.815, P < 0.001）。此外，地塞米松抑制Th2细胞因子分泌（IL-10水平在Dex/Af组为：5.27±0.85pg/ml; 在control/Af 组为: 15.14±1.40pg/ml, t = 14.761, P < 0.001），并引起免疫抑制。在DC-SIGN基因转染的DCs中，Th1细胞因子的分泌（IL-12 水平在Ad-DC-SIGN/Af组为: 471.98±166.31 pg/ml; 在control/Af组为: 33.35±5.98 pg/ml, t = 6.456, P = 0.001）及NF-κB的激活均有上调，DCs的吞噬功能也有所增加（吞噬率在Ad-DC-SIGN 组为: 74.0±3.4%; control组为: 64.7±6.8%, t = 3.104, P = 0.013）。 结论：树突状细胞表面DC-SIGN过表达对于曲霉感染起保护性作用。.
Keywords: Asepergillus fumigatus; Dendritic Cell-Specific Intercellular Adhesion Molecule-3-Grabbing Nonintegrin; Dendritic Cells; Immunity.