Zhao Yu, Jiang Yuteng, Wang Fengmei, Sun Li, Ding Mengyuan, Zhang Liyuan, Wu Beibei, Zhang Xiaoliang
Institute of Nephrology, Zhong Da Hospital, School of Medicine, Southeast University, Nanjing Jiangsu, China.
Department of Nephrology, Xuyi People's Hospital, Huaian, China.
PLoS One. 2024 Dec 31;19(12):e0314974. doi: 10.1371/journal.pone.0314974. eCollection 2024.
Imbalanced M1/M2 macrophage phenotype activation is a key point in diabetic kidney disease (DKD). Macrophages mainly exhibit the M1 phenotype, which contributes to inflammation and fibrosis in DKD. Studies have indicated that autophagy plays an important role in M1/M2 activation. However, the mechanism by which autophagy regulates the macrophage M1/M2 phenotype in DKD is unknown. Thus, the aim of the present study was to explore whether high glucose-induced macrophages switch to the M1 phenotype via the downregulation of STAT-3-mediated autophagy.
DKD model rats were established in vivo via the intraperitoneal injection of streptozocin (STZ). The rats were sacrificed at 18 weeks for histological and molecular analysis. RAW264.7 cells were cultured in vitro with 30 mM glucose in the presence or absence of a STAT-3 activator (colivelin) and an autophagy activator (rapamycin). Moreover, M1 and M2 macrophage activation models were established as a control group. Immunofluorescence and Western blot analyses were used to detect the expression of autophagy-related proteins (LC3 and Beclin-1), M1 markers (iNOS and CD11c) and M2 markers (MR and CD206).
In DKD, macrophages exhibit an M1 phenotype. Under high-glucose conditions, RAW264.7 macrophages switched to the M1 phenotype. Autophagy was downregulated in high glucose-induced M1 macrophages. Both the STAT-3 activator and the autophagy activator promoted the transition of glucose-induced M1 macrophages to M2 macrophages. Moreover, STAT-3 activation increased the expression of autophagy markers (LC3 and Beclin-1). However, the autophagy activator had no effect on STAT-3 phosphorylation.
High glucose promotes macrophage switching to the M1 phenotype via the downregulation of STAT-3-mediated autophagy.
M1/M2巨噬细胞表型激活失衡是糖尿病肾病（DKD）的关键环节。巨噬细胞主要呈现M1表型，这会促进DKD中的炎症和纤维化。研究表明自噬在M1/M2激活中起重要作用。然而，自噬调节DKD中巨噬细胞M1/M2表型的机制尚不清楚。因此，本研究的目的是探讨高糖诱导的巨噬细胞是否通过下调STAT-3介导的自噬而转变为M1表型。
通过腹腔注射链脲佐菌素（STZ）在体内建立DKD模型大鼠。18周时处死大鼠进行组织学和分子分析。RAW264.7细胞在有或无STAT-3激活剂（可利霉素）和自噬激活剂（雷帕霉素）的情况下于30 mM葡萄糖中体外培养。此外，建立M1和M2巨噬细胞激活模型作为对照组。采用免疫荧光和蛋白质印迹分析检测自噬相关蛋白（LC3和Beclin-1）、M1标志物（诱导型一氧化氮合酶和CD11c）和M2标志物（甘露糖受体和CD206） 的表达。
在DKD中，巨噬细胞呈现M1表型。在高糖条件下，RAW264.7巨噬细胞转变为M1表型。高糖诱导的M1巨噬细胞中自噬下调。STAT-3激活剂和自噬激活剂均促进葡萄糖诱导的M1巨噬细胞向M2巨噬细胞的转变。此外，STAT-激活增加了自噬标志物（LC3和Beclin-1）的表达。然而，自噬激活剂对STAT-3磷酸化没有影响。
高糖通过下调STAT-3介导的自噬促进巨噬细胞向M1表型转变。
