Inhaled Micelle of Antimicrobial Protein-Polymer Conjugate with Less Positive Charge Leads to Better Mucus Penetration and Enhanced Gram-Negative Pneumonia Therapy.

Clinical therapy of multidrug-resistant (MDR) Gram-negative (GN) ESKAPE pathogens-induced pneumonia remains a serious challenge. Antimicrobial proteins (AMPs) are a promising alternative for treating MDR bacterial infections, but their effectiveness is limited by instability, narrow-spectrum activity, and poor pharmacokinetics. Although conjugated or complexed cationic polymers can enhance the antimicrobial spectrum and potency of AMPs, they also cause AMPs to interact excessively with biomacromolecules in vivo, potentially reducing their therapeutic efficacy. Herein, screening of an ultra-acid-sensitive diblock copolymer-lysozyme conjugate to self-assemble into LPOBE micelle with enhanced stability. In acidic conditions, protonated LPOBE with low positive charge showed great serum protein-nonfouling ability and yielded highly effective bactericidal activity, achieving a 99.9% reduction in three MDR GN ESKAPE strains. Inhalation delivery can achieve high local concentrations of AMPs, but mucus in the lower respiratory tract impedes their penetration into infected areas due to the positive charge of AMPs. Furthermore, bacterial pneumonia is often accompanied by excessive inflammation. Therefore, we further developed a 'One-Stone-Two-Birds' strategy by loading sodium butyrate (NaBu), a small molecule immunomodulator, to form negatively charged LPOBEN, which improves both mucus penetration and anti-inflammatory effects of LPOBE. This system offers a novel theoretical foundation to develop high-performance AMP-based nanomedicines for clinical therapy.