CCL5 mRNA-enriched small extracellular vesicles from renal tubular epithelial cells enhance macrophage inflammatory responses in diabetic nephropathy.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.