Department of Laboratory Diagnosis, The First Affiliated Hospital of Harbin Medical University, 23 Youzheng Street, Nangang District, Harbin, 150001, Heilongjiang, People's Republic of China.
Inflamm Res. 2020 May;69(5):509-521. doi: 10.1007/s00011-020-01334-0. Epub 2020 Mar 16.
Lipopolysaccharide (LPS)-induced acute kidney injury (AKI) is associated with an abnormal immune response. Accumulating evidence has demonstrated that aquaporin 1 (AQP1) prevents kidney tissue injury in LPS-induced AKI by mediating immune response. However, the underlying mechanisms remain obscure. Macrophages as immune cells with multiple phenotypes are important mediators in tissue homeostasis and host defense. We propose that macrophage polarization is implicated in AQP1-mediated immune response.
Herein we established sepsis-induced AKI model rats through intraperitoneal injection of LPS into Wistar rats to reveal immune mechanism of damage. We also used LPS-induced mouse RAW264.7 cells to elucidate the molecular mechanism of macropage polarization.
Histopathology showed that renal tubular epithelial cells in the model group were swollen, inflammatory exudation was obvious and the inflammatory factors, interleukin-6 (IL-6) and tumor necrosis factor α (TNF-α) were increased. Western blotting showed PI3K was upregulated in the model group. Serum creatinine and urea nitrogen increased after LPS injection. Renal AQP1 mRNA is downregulated and serum AQP1 protein increased first and then decreased in LPS-induced AKI rats. M2 macrophage markers (Arg-1, CD206) were increased in repair stage. In addition, treatment of murine macrophages (RAW264.7) with AQP1 siRNA resulted in decreased PI3K activation and M2 polarization, but increased IL-6 and TNF-α. Moreover, inhibiting PI3K with wortmannin imitated the results of AQP1 silencing.
Macrophage M2 polarization is likely the cellular mechanism underlying the anti-AKI property of AQP1, and PI3K activation is involved in the AQP1-induced M2 phenotype switch.
脂多糖（LPS）诱导的急性肾损伤（AKI）与异常的免疫反应有关。越来越多的证据表明，水通道蛋白 1（AQP1）通过调节免疫反应来防止 LPS 诱导的 AKI 中的肾组织损伤。然而，其潜在机制尚不清楚。巨噬细胞作为具有多种表型的免疫细胞，是组织稳态和宿主防御的重要介质。我们提出巨噬细胞极化与 AQP1 介导的免疫反应有关。
本研究通过向 Wistar 大鼠腹腔内注射 LPS 建立脓毒症诱导的 AKI 模型大鼠，以揭示损伤的免疫机制。还使用 LPS 诱导的小鼠 RAW264.7 细胞来阐明巨噬细胞极化的分子机制。
组织病理学显示，模型组肾小管上皮细胞肿胀，炎症渗出明显，炎症因子白细胞介素-6（IL-6）和肿瘤坏死因子-α（TNF-α）增加。Western blot 显示模型组 PI3K 上调。LPS 注射后血清肌酐和尿素氮升高。LPS 诱导的 AKI 大鼠肾 AQP1mRNA 下调，血清 AQP1 蛋白先升高后降低。修复期 M2 巨噬细胞标志物（Arg-1、CD206）增加。此外，AQP1 siRNA 处理小鼠巨噬细胞（RAW264.7）导致 PI3K 激活减少和 M2 极化，IL-6 和 TNF-α 增加。此外，用wortmannin 抑制 PI3K 模仿了 AQP1 沉默的结果。
巨噬细胞 M2 极化可能是 AQP1 抗 AKI 特性的细胞机制，PI3K 激活参与 AQP1 诱导的 M2 表型转换。
