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Abstract: TH-PO849

High Glucose Promotes Macrophage Switching to M1 Phenotype via Down-regulating STAT-3-Mediated Autophagy

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Zhao, Yu, Institute of Nephrology, Zhong Da Hospital, Southeast University, School of Medicine, Nanjing, China
  • Zhu, Xiaodong, Institute of Nephrology, Zhong Da Hospital, Southeast University, School of Medicine, Nanjing, China
  • Jiang, Yuteng, Institute of Nephrology, Zhong Da Hospital, Southeast University, School of Medicine, Nanjing, China
  • Liu, Yuqiu, Institute of Nephrology, Zhong Da Hospital, Southeast University, School of Medicine, Nanjing, China
  • Zhang, Xiaoliang, Zhong Da Hospital, Southeast University, School of Medicine, Nanjing, JIangSu, China
Background

Imbalance of M1/M2 macrophages phenotype activation is a key point in diabetic nephropathy (DN). Macrophages mainly exhibit M1 phenotype, whcih contribute to the inflammation and fibrosis in DN. Studies indicate that autophage plays an important role in M1/M2 activation. However, the mechanism of autophage regulating macrophage M1/M2 phenotype in DN is unknown. Thus, the aim of this study is to explore whether high glucose induced macrophage switch to M1 phenotype via down-regulating STAT-3-mediated autophagy.

Methods

In vivo, DN model rats were established by intraperitoneal injection with streptozocin (STZ). Rats were sacrificed respectively at 18w for histological and molecular analysis. In vitro, RAW264.7 cells were cultured with 30mM glucose with or without autophagy regulator and STAT-3 regulator intervention. Meanwhile, the classical activation models of M1 and M2 macrophages were established as control group. The expressions of autophagy-related proteins (LC3, Beclin-1, p62), M1 markers (iNOS, TNF-α) and M2 markers (MR, Arg-1) were detected by immunofluorescence and Western Blot.

Results

In vivo, macrophages were exhibited to M1 phenotype in DN and displayed a lower level of autophagy. Additionally, iNOS expression was negative correlated with LC3 (r=-0.619, P<0.05) and pSTAT-3 (r=-0.951, P<0.05). In vitro, electronic microscope analysis showed intact autophagy (Fig.1). RAW264.7 macrophages switched to M1 phenotype under high glucose conditions. Autophagy was downregulated in such high glucose induced M1 macrophages. The expression of LC3 (autophagy maker) increased by STAT-3 activator. Meanwhile, both the STAT-3 activator and autophagy activator (rapamycin) promoted glucose-induced M1 macrophage translating to M2 macrophage. However, after inhibition of STAT-3 expression with STAT-3 siRNA, autophagy activator contributes to the reduction of the conversion of macrophages from M1 into M2 phenotype in high glucose-induced macrophage.

Conclusion

High glucose promotes macrophage switching to M1 phenotype via down-regulating STAT-3-mediated autophagy.