STAT3 阻断通过巨噬细胞驱动的炎症改善 LPS 诱导的肾损伤。

BACKGROUND: Signal transducer and activator of transcription 3 (STAT3), a multifaceted transcription factor, modulates host immune responses by activating cellular response to signaling ligands. STAT3 has a pivotal role in the pathophysiology of kidney injury by counterbalancing resident macrophage phenotypes under inflammation conditions. However, STAT3's role in acute kidney injury (AKI), particularly in macrophage migration, and in chronic kidney disease (CKD) through fibrosis development, remains unclear. METHODS: Stattic (a JAK2/STAT3 inhibitor, 5 mg/kg or 10 mg/kg) was administered to evaluate the therapeutic effect on LPS-induced AKI (L-AKI) and LPS-induced CKD (L-CKD), with animals sacrificed 6-24 h and 14 days post-LPS induction, respectively. The immune mechanisms of STAT3 blockade were determined by comparing the macrophage phenotypes and correlated with renal function parameters. Also, the transcriptomic analysis was used to confirm the anti-inflammatory effect of L-AKI, and the anti-fibrotic role was further evaluated in the L-CKD model. RESULTS: In the L-AKI model, sequential increases in BUN and blood creatinine levels were time-dependent, with a marked elevation of 0-6 h after LPS injection. Notably, two newly identified macrophage subpopulations (CD11bF4/80 and CD11bF4/80), exhibited population changes, with an increase in the CD11bF4/80 population and a decrease in the CD11bF4/80 macrophages. Corresponding to the FACS results, the tubular injury score, NGAL, F4/80, and p-STAT3 expression in the tubular regions were elevated. STAT3 inhibitor injection in L-AKI and L-CKD mice reduced renal injury and fibrosis. M2-type subpopulation with CD206 in CD11bF4/80 population increased in the Stattic-treated group compared with that in the LPS-alone group in the L-AKI model. Additionally, STAT3 inhibitor reduced inflammation driven by LPS-stimulated macrophages and epithelial cells injury in the co-culture system. Transcriptomic profiling identified 3 common genes in the JAK-STAT, TLR, and TNF signaling pathways and 11 common genes in the LPS with macrophage response. The PI3K-AKT (IL-6, Akt3, and Pik3r1) and JAK-STAT pathways were determined as potential Stattic targets. Further confirmation through mRNA and protein expressions analyses showed that Stattic treatment reduced inflammation in the L-AKI and fibrosis in the L-CKD mice. CONCLUSIONS: STAT3 blockade effectively mitigated inflammation by retrieving the CD11bF4/80 population, further emphasizing the role of STAT3-associated macrophage-driven inflammation in kidney injury.

背景：信号转导子和转录激活子 3（STAT3）是一种多功能转录因子，通过激活细胞对信号配体的反应来调节宿主免疫反应。STAT3 在肾损伤的病理生理学中起着关键作用，通过在炎症条件下平衡固有巨噬细胞表型来发挥作用。然而，STAT3 在急性肾损伤（AKI）中的作用，特别是在巨噬细胞迁移中的作用，以及在通过纤维化发展的慢性肾病（CKD）中的作用仍不清楚。

方法：用 Stattic（一种 JAK2/STAT3 抑制剂，5mg/kg 或 10mg/kg）给药，以评估其对 LPS 诱导的 AKI（L-AKI）和 LPS 诱导的 CKD（L-CKD）的治疗效果，分别在 LPS 诱导后 6-24 小时和 14 天处死动物。通过比较巨噬细胞表型和相关的肾功能参数来确定 STAT3 阻断的免疫机制。此外，还使用转录组分析来确认 L-AKI 的抗炎作用，并在 L-CKD 模型中进一步评估抗纤维化作用。

结果：在 L-AKI 模型中，BUN 和血肌酐水平的连续升高是时间依赖性的，在 LPS 注射后 0-6 小时有明显升高。值得注意的是，两个新鉴定的巨噬细胞亚群（CD11bF4/80 和 CD11bF4/80）表现出群体变化，CD11bF4/80 群体增加，CD11bF4/80 巨噬细胞减少。与 FACS 结果相对应，肾小管损伤评分、NGAL、F4/80 和管状区域的 p-STAT3 表达升高。在 L-AKI 和 L-CKD 小鼠中注射 STAT3 抑制剂可减轻肾损伤和纤维化。与 LPS 单独组相比，L-AKI 模型中 CD11bF4/80 群体中的 CD206 增加了 M2 型亚群。此外，STAT3 抑制剂减少了 LPS 刺激的巨噬细胞和上皮细胞损伤引起的炎症。转录组谱分析确定了 JAK-STAT、TLR 和 TNF 信号通路中的 3 个共同基因和 LPS 与巨噬细胞反应中的 11 个共同基因。PI3K-AKT（IL-6、Akt3 和 Pik3r1）和 JAK-STAT 途径被确定为潜在的 Stattic 靶点。通过 mRNA 和蛋白质表达分析的进一步证实表明，Stattic 治疗减轻了 L-AKI 中的炎症和 L-CKD 中的纤维化。

结论：STAT3 阻断通过恢复 CD11bF4/80 群体有效缓解炎症，进一步强调了 STAT3 相关的巨噬细胞驱动的炎症在肾损伤中的作用。