缺血预适应介导CD11c+树突状细胞调控Treg细胞减轻缺血再灌注急性肾损伤的机制研究

Acute kidney injury (AKI) is a clinical critical illness, and ischemic preconditioning (IPC) can reduce ischemia-reperfusion (I/R) AKI.But renal artery preischemia caused by in situ clamping of renal artery is difficult to be used in clinic.Immune mechanisms permeate the development of I/R AKI. Dendritic cells (DCs) are the bridges between innate immunity and adaptive immunity. The normal kidney DCs are in immature state, and they are the first to experience the stimulation of renal ischemic injury. Our previous experiments confirmed that IPC inhibited the maturation and differentiation of DCs resulting in renal protection. It is speculated that IPC inhibits the maturation of CD11c+DCs in the kidney and may activate Treg cells to induce immune tolerance. Using CD11c-DTR transgenic mice with DCs removed, we investigated: 1. IPC exerts renal protective effects by inhibiting the maturation of DCs in the kidney, leading to activation of Treg cells and immune tolerance. 2. Conditionally eliminating DCs can lead to weakened IPC kidney protection. 3. Immature DCs were infused into CD11c-DTR transgenic mice with DCs removed. IPC protection may be restored. In summary, it will be helpful to find immunotherapy of DCs in place of IPC in situ clamping of renal artery and provide a new method for clinical prevention and treatment of I/R AKI.

急性肾损伤（AKI）是临床危重症，缺血预适应（IPC）能减轻缺血再灌注(I/R)AKI，但原位钳夹肾动脉产生预缺血临床上难以应用。免疫机制贯穿I/R AKI的发生发展，树突状细胞（DCs）是固有免疫向适应性免疫转换的桥梁。正常肾脏DCs处于未成熟状态，最早感受肾脏缺血损伤刺激。我们前期实验证实IPC抑制DCs成熟分化产生肾保护作用。推测IPC抑制肾脏CD11c+DCs的成熟分化，可能通过激活Treg细胞导致免疫耐受。我们借助剔除DCs的CD11c-DTR转基因小鼠，探讨:1.IPC通过抑制肾脏DCs的成熟，导致Treg细胞激活产生免疫耐受发挥肾保护作用。2.条件性剔除DCs能导致IPC肾脏保护作用减弱。3.将未成熟DCs输注入剔除DCs的CD11c-DTR转基因小鼠体内，IPC保护作用可能恢复。综上，将有助于发现DCs输注的免疫治疗替代原位肾动脉IPC，为临床防治I/R AKI提供新方法。

急性肾损伤（AKI）是临床危重症，缺血预适应（IPC）能减轻缺血再灌注(I/R)AKI，但原位钳夹肾动脉产生预缺血临床上难以应用。免疫机制贯穿I/R AKI的发生发展，我们前期实验发现晚期缺血预处理(DIPC)可以通过抑制树突状细胞(DCs)的成熟来发挥其对肾脏IRI的保护作用，但其机制尚未明确。本研究旨在探讨DIPC通过未成熟dc (imDCs)介导Treg对小鼠肾IRI的保护机制。方法采用IRI小鼠模型、DIPC处理和CD11c + DCs (CD11c- dTR)基因敲除小鼠进行研究。流式细胞术检测肾、脾dc和Treg细胞的成熟分化情况。HE染色评价肾组织病理。同时检测肌酐(Cr)、氧化应激指标(SOD、MDA)和炎症因子(TNF-α、IL-10、IL-4)水平。然后，将未成熟树突状细胞imDCs与肾小管上皮细胞HK-2共培养，采用流式细胞术和荧光染色检测凋亡情况，评估缺氧-复氧(H/R)条件下HK-2的凋亡率。并用未成熟和成熟的树突状细胞免疫回输替代体外钳夹肾动脉预缺血，观察未成熟树突状细胞能否模拟DIPC对肾脏缺血再灌注急性肾损伤产生类似保护作用。结果DIPC可降低肾脏血肌酐水平，减轻病理性肾损害，减轻IRI引起的氧化应激和炎症反应。DIPC可以减少成熟dc的数量，增加Treg淋巴细胞在肾组织中的浸润，而dc的减少则逆转了这一过程。体外免疫细胞培养imDCs并回输DCs在敲除DCs-DTR转基因小鼠的DIPC模型上，imDCs回输能类似IPC产生减轻缺血再灌注AKI中肾组织损伤作用。体外实验在H/R模型中，与imDCs共培养的HK-2细胞凋亡减少。证实DIPC对I/R诱导AKI存在肾保护作用，而剔除CD11c+DCs会导致IPC的肾脏保护作用减弱。利用腺苷受体激动剂/抑制剂进行药物干预、体外免疫细胞培养imDCs并回输明确，干预DCs 及 AR/DC/Treg 通路在IPC对肾I/R的保护中发挥着耐受性保护作用。结论DIPC可调节DCs向imDCs分化，进而影响Treg细胞的分化水平和分布，发挥对肾IRI的保护作用。