The profile of miRNAs in lung fibroblast-derived extracellular vesicles from idiopathic pulmonary fibrosis (IPF) patients or non-IPF individuals.

Accelerated senescence in lung epithelial cells is known to play a key role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). However, the exact mechanisms underlying the IPF-related epithelial cell phenotype have yet to be elucidated. Increasing evidence supports the concept that extracellular vesicles (EVs), including exosomes and microvesicles, mediate intercellular communication that contributes to diverse aspects of physiology and pathogenesis. Here, we demonstrate that lung fibroblasts (LFs) from IPF patients accelerate epithelial cell senescence via EV-mediated transfer of LF-derived pathogenic cargo to lung epithelial cells. Mechanistically, IPF LF-derived EVs increase mitochondrial reactive oxygen species (mtROS) and associated mitochondrial damage in lung epithelial cells, leading to mtROS-mediated activation of the DNA damage response and subsequent epithelial cell senescence. We show that IPF LF-derived EVs contain elevated levels of miR-23b-3p and miR-494-3p that are responsible for suppressing SIRT3, resulting in the EV-induced phenotypic changes of lung epithelial cells. Furthermore, we observe that miR-23b-3p and miR-494-3p expression increases in lung epithelial cells from IPF patients’ lungs. Finally, the levels of miR-23b-3p and 494-3p found in IPF LF-derived EVs correlate positively with IPF disease severity. These findings reveal that the accelerated epithelial cell mitochondrial damage and senescence observed during IPF pathogenesis are caused by a novel mechanism in which SIRT3 is suppressed by miR-containing EVs derived from IPF fibroblasts. We pooled six of the individual IPF LF-derived EV samples and six of the individual non-IPF LF-derived EV samples. Individual EV sample was isolated from the conditioned media of primary lung fibroblasts by ultratrancefugation. Total RNAs were extracted from these EVs. Microarray analysis was performed using 20ng of the RNAs.