Biomimetic lipid Nanocomplexes incorporating STAT3-inhibiting peptides effectively infiltrate the lung barrier and ameliorate pulmonary fibrosis.

Activation of signal transducer and activator of transcription 3 (STAT3) under conditions of inflammation plays a crucial role in the pathogenesis of life-threatening pulmonary fibrosis (PF), initiating pro-fibrotic signaling following its phosphorylation. While there have been attempts to interfere with STAT3 activation and associated signaling as a strategy for ameliorating PF, potent inhibitors with minimal systemic toxicity have yet to be developed. Here, we assessed the in vitro and in vivo therapeutic effectiveness of a cell-permeable peptide inhibitor of STAT3 phosphorylation, designated APTstat3-9R, for ameliorating the indications of pulmonary fibrosis. Our results demonstrate that APTstat3-9R formulated with biomimetic disc-shaped lipid nanoparticles (DLNPs) markedly enhanced the penetration of pulmonary surfactant barrier and alleviated clinical symptoms of PF while causing negligible systemic cytotoxicity. Taken together, our findings suggest that biomimetic lipid nanoparticle-assisted pulmonary delivery of APTstat3-9R may be a feasible therapeutic option for PF in the clinic, and could be applied to treat other fibrotic diseases. STATISTICAL ANALYSES: All in vitro and in vivo experiments were performed at least three times, and results are presented as means ± standard error of the mean (SEM). Statistical analyses were performed using a one-way analysis of variance (ANOVA) followed by Tukey's post hoc tests to compare the difference between the two groups. P-values <0.05 were considered statistically significant; individual P-values are indicated by asterisks in figures (***P < 0.001, **P < 0.01, *P < 0.05).