Senescent renal tubular cells derived extracellular vesicles transported miR-20a and miR-21 induced macrophage-to-myofibroblast transition in renal fibrosis after ischemia reperfusion injury.

In our investigation, we aimed to shed light on the role of senescent cells in renal fibrosis, considering the observed correlation between renal tubular epithelial cell senescence and the presence of renal fibrosis. Our findings confirm the manifestation of senescence characteristics in renal tubular epithelial cells during renal fibrosis and establish their capacity to trigger a transition from macrophages to myofibroblasts, known as macrophage-myofibroblast transition (MMT). Additionally, our study uncovered that extracellular vesicles released by senescent HK-2 cells (sHK-2) play a pivotal role in facilitating MMT. Subsequently, we investigated the miRNA profile in sHK-2-derived extracellular vesicles (sHK-2-EVs) and confirmed the elevated abundance of specific miRNAs, including miR-20a-5p and miR-21-5p, compared to normal HK-2-EVs. Notably, these miRNAs possess the capability to induce M2-like polarization in macrophages and enhance the expression of TGF-β. Moreover, TGF-β can stimulate macrophages to produce miR-20a-5p and miR-21-5p, establishing a positive feedback loop that amplifies the TGF-β/Smad pathway and facilitates the process of macrophage-myofibroblast transition.