Inhaled Bovine Lactoferrin Modulates the p47phox–MPO–NETosis Axis in Acute Lung Injury: Implications for Bioengineered Nanomedicine in Respiratory Infections

Guoan Xiang^1*Di Lian¹jingchao cao²zhongkuo yu¹yaru liu¹Xiaoxiang Hu²Shoulong Deng^3*Xin Li⁴lixin xie¹

• ¹College of Pulmonary & Critical Care Medicine, the Eighth Medical Center of Chinese PLA General Hospital, beijing, China
• ²China Agricultural University, Beijing, China
• ³National Science Center for Model Animals, China Agricultural University, Beijing, China
• ⁴Chinese PLA General Hospital, beijing, China

Excessive oxidative burst and dysregulated neutrophil extracellular trap (NET) formation contribute to tissue damage in acute lung injury (ALI), and are largely driven by the combined actions of NADPH oxidase 2 (NOX2) and myeloperoxidase (MPO). While lactoferrin (LTF) is a known multifunctional immunomodulatory glycoprotein, its precise role in modulating the NOX2–MPO– NETosis axis in ALI remained undefined. To address this, we utilized a time-course model of lipopolysaccharide (LPS)–induced ALI in C57BL/6N mice. LPS induced typical ALI pathology that peaked between days 1 and 3 (D1-D3). Quantitative lung proteomics and subsequent bioinformatics consistently highlighted NET formation as a centrally enriched early KEGG pathway. Furthermore, LTF emerged as a key protein–protein interaction (PPI) hub closely connected to p47phox (encoded by Ncf1) and MPO. Subsequently, evaluation of aerosolized bovine lactoferrin (bLF) demonstrated significant mitigation of ALI pathology, reducing lung injury, pro-inflammatory cytokines, and neutrophil recruitment. Mechanistically, bLF suppressed NETosis by reducing p47phox and MPO expression. Crucially, bLF also diminished p47phox phosphorylation in vivo, consistent with reduced NOX2 activation. These findings identify LTF as a critical dynamic regulator of the p47phox–MPO– NETosis axis in LPS-induced ALI. These mechanistic findings highlight bLF as a promising candidate for further translational evaluation and support the rationale for developing bioengineered, lactoferrin‑based nanomedicines aimed at modulating innate immunity and mitigating neutrophil‑driven lung injury in respiratory infectious diseases.