Lung-Targeted Delivery and Reactive Oxygen Species-Triggered Activation of Pro-protein for Antibacterial Therapy

Protein therapeutics exhibit unparalleled target specificity but are often compromised by limited spatiotemporal control, leading to off-target effects and reduced in vivo efficacy. Herein, we report a modular chemical approach for the programmable regulation of protein activity via chemical conjugation using a redox-responsive diazo-boronate (DEOB) reagent. DEOB enables the chemoselective and traceless caging of essential protein carboxylic acid residues under biocompatible conditions, effectively silencing enzymatic functions. Upon exposure to reactive oxygen species, a hallmark of inflammatory and infectious microenvironments, the DEOB-protein adduct undergoes a rapid, self-immolative cascade reaction, releasing the native carboxylate and restoring protein function. Moreover, we demonstrate that the delivery of DEOB-caged "pro-proteins" using tissue-specific lipid nanoparticles (tsLNPs) allows pulmonary targeting and in situ protein activation. In a murine model of Staphylococcus aureus-infected pneumonia, the systematic administration of lung-targeting LNPs delivered DEOB-conjugated lysozyme (DEOB-Lyz) facilitated site-specific activation within the infected lung. This integrated approach achieved robust bacterial clearance and significantly improved survival rates while minimizing systemic toxicity. This study provides a versatile strategy that couples stimuli-responsive protein bioconjugation with tissue-specific delivery, offering a robust paradigm for the development of targeted protein therapeutics against inflammatory and oxidative stress-related disorders.