CCL5 Mrna-Enriched Small Extracellular Vesicles from Renal Tubular Epithelial Cells Enhance Macrophage Inflammatory Responses in Diabetic Nephropathy.

Small extracellular vesicles (sEVs) derived from tubular epithelial cells (TECs) are important mediators of tubular–immune cell communication in diabetic nephropathy (DN). However, the RNA cargo involved in TEC–macrophage inflammatory communication remains incompletely understood. This study investigated whether sEV-associated CCL5 mRNA contributes to inflammatory communication between TECs and macrophages in DN. Urinary sEV transcriptomic analysis and clinical association analysis were performed to identify DN-associated RNA cargo. In vitro, sEVs released from TECs exposed to high glucose were incubated with macrophages, and macrophage migration, inflammatory cytokine expression, and TLR4/MyD88/NF-κB-related signaling were evaluated. Ccl5 knockdown in TECs and actinomycin D experiments were used to examine sEV-associated Ccl5 mRNA enrichment, transfer, and function. CCL5 mRNA was increased in urinary sEVs in DN and was associated with tubulointerstitial injury in clinical samples. High-glucose-treated TECs released sEVs enriched in Ccl5 mRNA that were internalized by macrophages and enhanced macrophage migration, inflammatory cytokine expression, and TLR4/MyD88/NF-κB-related signaling. Ccl5 knockdown attenuated these effects, while actinomycin D experiments further supported the transfer of vesicle-associated Ccl5 mRNA. Activated macrophages also promoted injury-related responses in glomerular cells. These findings suggest that TEC-derived sEV-associated Ccl5 mRNA may contribute to TEC-to-macrophage inflammatory communication in DN, with activated macrophages potentially propagating injury-related responses to glomerular cells.