The Role of Macrophage-Derived Exosomes in Reversing Peritoneal Fibrosis: Insights from Astragaloside IV

Peritoneal dialysis (PD) is a successful renal replacement therapy for end-stage renal disease. Long-term PD causes mesothelial-mesenchymal transition (MMT) of peritoneal mesothelial cells (PMCs), leading to peritoneal fibrosis (PF), which reduces the efficiency of PD. Macrophages are thought to play a role in the onset and perpetuation of peritoneal injury. However, the mechanisms by which macrophages-PMCs communication regulates peritoneal fibrosis are not fully understood resulting in a lack of disease-modifying drugs. Astragaloside IV (AS-IV) possessed anti-fibrotic effect towards PF in PD whereas the mechanistic effect of AS-IV in PD is unknown. The primary macrophages were extracted and treated with LPS or AS-IV, then co-cultured with primary PMCs in transwell plates. The macrophage-derived exosomes were extracted and purified by differential centrifugation, then co-cultured with primary PMCs. Small RNA-seq was used to detect differential miRNAs in exosomes, and then KEGG analysis and q-PCR were performed for validation. In vivo PD rat models were established by inducing with high-glucose peritoneal dialysis fluid and different concentrations of AS-IV and exosomes were intraperitoneal injection. Through qRT-PCR, western blotting, and luciferase reporting, candidate proteins and pathways were validated in vivo and in vitro. The functions of the validated pathways were further investigated using the mimic or inhibition strategy. PF and inflammatory situations were assessed. We found AS-IV reversed the MMT of PMCs caused by LPS-stimulated macrophages and the improving effect was mediated by macrophage-derived exosomes in vitro. We also demonstrated that AS-IV significantly reduced the MMT of PMCs in vitro or PF in a rat PD model via regulating exosome-contained miR-204-5p which targets Foxc1/β-catenin signaling pathway. AS-IV attenuates macrophage-derived exosomes induced fibrosis in PD through the miR-204-5p/Foxc1 pathway.