ADSC-derived exosomes inhibit myofibroblast transdifferentiation and attenuate airway stenosis via METTL3-mediated m6A modification of TLR2

OBJECTIVE: To investigate the therapeutic potential of adipose-derived stem cell exosomes (ADSC-Exos) in airway repair and the underlying mechanisms, with a particular focus on the role of N6-methyladenosine (m6A) modification. METHODS: ADSC-Exos were isolated and characterized via ultracentrifugation. In vitro effects of ADSC-Exos were evaluated using transforming growth factor-β1 (TGF-β1)-induced fibroblast models. A rabbit airway injury model was established, and exosomes were locally administered. Molecular mechanisms were investigated using methylated RNA immunoprecipitation sequencing (MeRIP-seq), RNA-seq, Western blotting, and qRT-PCR. RESULTS: ADSC-Exos significantly upregulated the expression of m6A methyltransferase methyltransferase-like 3 (METTL3) in both in vivo and in vitro experiments. This upregulation further enhanced the m6A methylation level of Toll-like receptor 2 (TLR2) mRNA, leading to decreased TLR2 expression. Additionally, the phosphatidylinositol 3-kinase-protein kinase B (PI3K-AKT) signaling pathway was inhibited, accompanied by decreased expression of the myofibroblast markers α-smooth muscle actin (α-SMA) and Collagen I. Notably, overexpression of METTL3 reversed the inhibitory effects induced by ADSC-Exos on myofibroblast differentiation. CONCLUSION: ADSC-Exos promote airway repair by upregulating METTL3, which enhances m6A methylation of TLR2 mRNA, downregulates TLR2, and inhibits PI3K-AKT pathway activation, thereby inhibiting myofibroblast differentiation. This study reveals a novel epigenetic mechanism for the treatment of benign airway stenosis (BAS).