Vitamin E Nanoemulsion Loaded Exosomes Attenuates Bleomycin-Induced Pulmonary Fibrosis by Inhibiting NLRP3-Mediated Pyroptosis and Fibrotic Signaling

This study aimed to investigate the protective effects of nano-formulated vitamin E combined with mesenchymal stem cell (MSC)-derived exosomes in bleomycin-induced lung fibrosis. AD-MSCs were isolated, expanded, and characterized by spindle morphology with high CD105/CD73 and low CD34/CD45 expression. Exosomes isolated from these cells displayed typical spherical morphology (131 nm), high CD81/CD63/CD9 expression, and low CD14. Skin fibrosis was induced in rats by subcutaneous administration of bleomycin. Animals subsequently received free vitamin E, nano-formulated vitamin E, or exosomes loaded with nano-formulated vitamin E. The antifibrotic efficacy of these treatments was assessed using biochemical, molecular, histopathological, and immunohistochemical analyses. Vitamin E nanoemulsion (mean of 48 nm, PDI 0.221, zeta -27.6 mV) was successfully loaded into the exosomes (EE 86.3%, LE 19.8%), yielding stable vesicles (137 nm) with excellent cytocompatibility. The formulation markedly attenuated bleomycin-induced fibrotic injury by restoring redox balance, reduction of TNF-α and TGF-β1 and attenuated extracellular matrix remodeling by decreasing collagen I, α-SMA, MMP-2, and TIMP-1. Moreover, inhibition of the NLRP3/caspase-1/GSDMD pathway and IL-1β indicated suppression of pyroptosis. VEGFR2 expression was also reduced, accompanied by marked improvement in histopathological alterations. The combination therapy exerted pronounced anti-fibrotic effects through coordinated antioxidant, anti-inflammatory, anti-pyroptotic, anti-ECM-remodeling, and anti-angiogenic mechanisms.