Dexamethasone-loaded glycyrrhiza protein nanoparticles reprogram macrophages to an anti-inflammatory phenotype via STAT6/IRF4 activation for alleviating sepsis-induced acute respiratory distress syndrome

Sepsis-induced acute respiratory distress syndrome (ARDS) is a life-threatening condition with uncontrolled inflammation and lung damage. Current therapies are limited, and reprogramming macrophages from pro-inflammatory M1 to anti-inflammatory M2 phenotypes via STAT6/IRF4 activation offers a promising strategy. Dexamethasone-loaded glycyrrhiza protein nanoparticles (Dex@GNPs) were synthesized by extracting GP, denaturing it with phosphoric acid, cross-linking with glutaraldehyde, and encapsulating dexamethasone. Physicochemical properties (size,<i>ζ</i>-potential, drug release) were characterized.<i>In vitro</i>studies used lipopolysaccharide (LPS)-stimulated MH-S macrophages;<i>in vivo</i>efficacy was evaluated in murine ARDS models (LPS intratracheal injection or cecal ligation and puncture). Macrophage polarization (flow cytometry, immunofluorescence), STAT6/IRF4 pathway activation (Western blot), lung histopathology (H&E), and inflammation markers (bronchoalveolar lavage fluid cytokines, ELISA) were assessed. Dex@GNPs exhibited favorable physicochemical properties (hydrodynamic diameter: 374 ± 12 nm;<i>ζ</i>-potential: -22 ± 4 mV) with pH-responsive drug release (79% cumulative release at pH 5.5 within 24 h).<i>In vitro</i>, Dex@GNPs significantly reprogrammed M1 macrophages to M2 phenotypes, increasing CD206⁺cells from 5% to 25% and upregulating STAT6/IRF4 expression compared to LPS-stimulated cells.<i>In vivo</i>, Dex@GNPs selectively targeted inflamed lungs, reduced alveolar damage, suppressed pro-inflammatory cytokines (TNF-<i>α</i>, IL-6, MCP-1 reduced by 81%, 83%, 86% respectively), and restored alveolar-capillary barrier integrity, outperforming free dexamethasone. Dex@GNPs synergize GP's targeting and dexamethasone's anti-inflammatory effects to alleviate sepsis-induced ARDS by STAT6/IRF4-mediated macrophage polarization, offering a biocompatible nanotherapeutic platform.