腺苷A2B受体信号通路促肾纤维化机制：对巨噬细胞募集和极化的影响

Our previous studies demonstrated that persistent up-regulated adenosine promoted renal fibrosis through adenosine A2B receptor signaling. However, the mechanism is unclear. Macrophage recruitment and polarization play an important role in the development of renal fibrosis. We found adenosine A2B receptor deficiency can reduce renal macrophage infiltration, and bioinformatic analysis indicated some cytokines related to macrophage recruitment and polarization might be regulated by adenosine A2B receptor. Based on the findings, we hypothesized that adenosine A2B receptor signaling might promote renal fibrosis by affecting macrophage recruitment and polarization. Using Angiotensin II infused or unilateral ureteral obstructed mouse model, we plan to observe the effect of adenosine A2B receptor (agonist/antagonist or adenosine A2B receptor knockout) on macrophage recruitment and polarization, analysis the expression of cytokines related to macrophage recruitment and polarization, and finally elucidate the mechanism of adenosine A2B receptor signaling promoting renal fibrosis by affecting macrophage recruitment and polarization. Our study is of great significance on providing new sights to prevent renal fibrosis.

申请人近年研究表明持续上调的腺苷通过腺苷A2B受体信号通路促进肾纤维化，但其作用机制并不十分清楚。巨噬细胞的募集和极化在肾纤维化中发挥了重要作用。本课题组新近研究发现腺苷A2B受体基因敲除可以减少肾脏巨噬细胞的浸润，生物信息学方法分析提示巨噬细胞募集和极化相关的细胞因子可能受腺苷A2B受体信号通路调控，据此我们提出“持续上调的腺苷可通过腺苷A2B受体信号通路影响巨噬细胞募集和极化促进肾纤维化”的假说。本项目拟采用单侧输尿管梗阻或血管紧张素II诱导的慢性肾纤维化小鼠模型，观察腺苷A2B受体激动剂/拮抗剂或腺苷A2B受体基因敲除对肾脏巨噬细胞募集和极化的影响，分析与巨噬细胞募集和极化相关因子的表达情况，最后从转录水平研究A2B受体信号通路对巨噬细胞募集和极化相关因子的调控机制，对于揭示腺苷A2B受体信号通路在肾纤维化中的作用具有重要意义。

原发性或继发性肾脏疾病如不能尽早终止均可发生肾纤维化，进而出现肾功能衰竭。各种损伤后的持续性炎症反应启动和加速肾损伤，促进肾纤维化的发生发展。本项目通过构建血管紧张素II（Ang II）和单侧输尿管梗阻（UUO）诱导的经典慢性肾损伤小鼠模型，利用药理学、遗传学和生物化学等方法研究发现：（1）巨噬细胞上腺苷A2B受体是控制其在慢性肾损伤肾组织中浸润和极化的关键分子，选择性腺苷A2B受体抑制剂PSB1115对肾纤维化有保护作用；（2）硫化氢可通过抑制慢性肾脏病中肾组织 NLRP3 炎性体活化从而减轻肾脏巨噬细胞浸润和极化，减轻炎症反应，延缓肾纤维化；（3）溴结构域相关蛋白 4抑制剂 JQ1 可通过抑制肾小管上皮细胞转分化从而减轻肾脏纤维化；（4）中性粒细胞/淋巴细胞比值与 SLE 患者的肾脏受累、浆膜炎及疾病活动密切相关，提示其作为一种新的炎症指标，对评估 SLE 疾病活动及脏器受累具有重要意义；（5）AIM2 炎性体主要在 II 型狼疮肾炎肾小球上表达，NLRP1 炎性体炎性体主要在 II 型和 IV 狼疮肾炎肾小管上表达，NLRP3 炎性体炎性体主要在 IV 型狼疮肾炎肾小管上表达，且 NLRP3 炎性体的表达水平与肾脏活动性指数评分呈正相关。综上所述，本项目深入研究了慢性肾脏病的炎性发病机制并探索了以控制肾脏炎性损伤为主的靶向药物，为今后慢性肾脏病防治药物的研发提供了坚实基础。