Role of the M1 macrophage response in the progression of chronic kidney disease

描述（由申请人提供）： 全身免疫反应在慢性肾脏病（CKD）的发病机制中发挥着越来越重要的作用。巨噬细胞通过分化成两种功能表型来帮助形成免疫反应：M1或M2细胞。M1巨噬细胞分泌促炎细胞因子并介导组织损伤，而M2巨噬细胞分泌抗炎细胞因子并辅助组织修复。与M1应答在介导肾损伤中的作用一致，我们使用CKD模型的初步研究已经揭示了巨噬细胞向肾脏中的显著浸润，以及M1效应细胞因子白细胞介素-1（IL-1）和肿瘤坏死因子-α（TNF-α）的增强的肾脏表达。因此，我们假设M1巨噬细胞通过IL-1和TNF-α的作用促进CKD的进展。IL-1受体（IL-1 R）和TNF-受体1（TNFR 1）双重缺陷的小鼠不能产生M1免疫应答（M1 KO）。因此，为了直接测试M1应答对CKD的贡献，我们将测量血管紧张素II（Ang II）依赖性高血压和单侧输尿管梗阻（UUO）后M1 KO小鼠和对照组的肾损伤和纤维化参数。M1/M2巨噬细胞分化的潜在调节因子包括T淋巴细胞亚群和巨噬细胞上的1型血管紧张素（AT 1）受体。在这方面，促炎性Th 1 T细胞分泌IFN-g，驱动巨噬细胞向M1表型，而在我们的初步研究中，直接激活巨噬细胞上的AT 1受体限制了巨噬细胞和肾脏中促炎性M1细胞因子的表达，并改善了肾损伤。因此，我们认为，在CKD的设置，M1巨噬细胞的反应被放大的Th 1细胞的行动，但抑制AT 1受体的激活巨噬细胞。我们已经发现，缺乏Th 1应答的小鼠（Tbet KO）在高血压的情况下具有钝化的肾损伤应答和减弱的M1细胞因子的肾表达。因此，为了确定肾纤维化过程中Th 1 T细胞对M1巨噬细胞应答的影响，我们将检查Tbet KO小鼠和对照组UUO后的肾损伤和M1/M2巨噬细胞分化。为了研究巨噬细胞AT 1受体在限制M1巨噬细胞介导的肾损伤中的作用，我们将进一步评估UUO和高血压诱导的肾损伤以及缺乏巨噬细胞AT 1受体（Macro KO）和对照小鼠中巨噬细胞的M1/M2分化。为了在体外确定巨噬细胞AT 1受体限制肾细胞损伤的机制，我们将野生型和Macro KO巨噬细胞与M1 KO、IL-1 R KO、TNFR 1 KO肾小管细胞和对照共培养，然后检查肾细胞损伤的参数。我们认为巨噬细胞上AT 1受体的激活将减弱M1巨噬细胞的反应，进而改变M1细胞因子信号通路，以保护肾脏免受有害刺激。检查这些途径应该会导致更有效的预防进展性CKD的策略。

DESCRIPTION (provided by applicant): Systemic immune responses play an increasingly recognized role in the pathogenesis of chronic kidney disease (CKD). Macrophages help to shape immune responses by differentiating into 2 functional phenotypes: M1 or M2 cells. M1 macrophages secrete pro-inflammatory cytokines and mediate tissue injury whereas M2 macrophages secrete anti-inflammatory cytokines and aid in tissue repair. Consistent with a role for M1 responses in mediating kidney damage, our preliminary studies using CKD models have revealed impressive infiltration of macrophages into the kidney coupled with enhanced renal expression of the M1 effector cytokines Interleukin-1 (IL-1) and tumor necrosis factor-a (TNF-a). We therefore hypothesize that M1 macrophages contribute to the progression of CKD through the actions of IL-1 and TNF-a. Mice doubly deficient for the IL-1 receptor (IL-1R) and TNF-receptor 1 (TNFR1) are unable to mount an M1 immune response (M1 KO). Accordingly, to directly test the contribution of the M1 response to CKD, we will measure parameters of kidney injury and fibrosis in M1 KO mice and controls following angiotensin II (Ang II)- dependent hypertension and unilateral ureteral obstruction (UUO). Potential regulators of M1/M2 macrophage differentiation include T lymphocyte subpopulations and type 1 angiotensin (AT1) receptors on macrophages. In this regard, pro-inflammatory Th1 T cells secrete IFN-g, driving macrophages toward the M1 phenotype, whereas in our preliminary studies activation of AT1 receptors directly on macrophages limits the expression of pro-inflammatory M1 cytokines both in the macrophage and the kidney and ameliorates renal damage. We therefore posit that in the setting of CKD, M1 macrophage responses are amplified by actions of Th1 cells but are inhibited by the activation of AT1 receptors on macrophages. We have already found that mice lacking Th1 responses (Tbet KO) have a blunted kidney injury response and muted renal expression of M1 cytokines in the setting of hypertension. Therefore, to determine the impact of Th1 T cells on M1 macrophage responses during renal fibrosis, we will examine kidney damage and M1/M2 macrophage differentiation in Tbet KO mice and controls following UUO. To examine the role of the macrophage AT1 receptor in limiting kidney damage mediated by M1 macrophages, we will further assess UUO- and hypertension-induced kidney injury and M1/M2 differentiation of macrophages in mice lacking the macrophage AT1 receptor (Macro KO) and controls. To define in vitro the mechanisms through which the macrophage AT1 receptor limits renal cell injury, we will co-culture wild-type and Macro KO macrophages with M1 KO, IL-1R KO, TNFR1 KO renal tubular cells and controls and then examine parameters of renal cell injury. We submit that activation of the AT1 receptor on macrophages will blunt the M1 macrophage response and in turn modify M1 cytokine signaling pathways to protect the kidney upon exposure to injurious stimuli. Examining these pathways should lead to more effective strategies for preventing progressive CKD.