M2 macrophage-derived exosomal miR-25-3p improves high glucose-induced podocytes injury through activation autophagy via inhibiting DUSP1 expression.

Diabetic nephropathy (DN) is the primary reason of chronic kidney disease. The aim of our study is to explore the role and action mechanism of M2 macrophage-derived exosomes in high glucose (HG)-induced podocytes injury. Here, 30 mmol/L of HG was used to induce podocytes injury. Annexin V-FITC/PI double staining was performed to measure podocytes apoptosis, and western blot was carried out to ensure proteins expression. The shape of exosomes was identified using TEM. Besides, the expression of miR-25-3p was determined by qRT-PCR, FAM-labeled miR-25-5p combined with DiI-labeled exosomes were utilized to explore the uptake of podocytes to exosomes. Relationship between miR-25-3p and DUSP family members was ensued by luciferase activity assay. In the beginning, we found that M2 macrophage ameliorated HG-induced podocytes apoptosis and epithelial-mesenchymal transition through secreting exosomes. Subsequently, highly expressed miR-25-3p was found in M2 macrophage-derived exosomes that effectively improved HG-induced podocytes injury. Furthermore, inhibition of miR-25-3p in M2 macrophage inefficiently repressed HG-induced podocytes injury, thus we proposed that M2 macrophage attenuated podocytes injury through secreting exosomal miR-25-3p. Then, we used an autophagy inhibitor to stimulate podocytes, and demonstrated that M2 macrophage-derived exosomal miR-25-3p improved HG-induced podocytes injury through activating autophagy. Finally, DUSP1 was proved to be a downstream target and mediated the inhibition of exosomal miR-25-3p to HG-induced podocytes injury. Our results indicated that M2 macrophage could improve HG-induced podocytes injury via secreting exosomal miR-25-3p to activate autophagy of the cells through suppressing DUSP1 expression. We proved a newly potential therapy strategy for DN treatment.