Background
The need to understand key players driving pulmonary inflammation and fibrosis in COVID-19 patients leading to effective preventive strategies is imminent. Excessive neutrophil activation, including extracellular trap (NET) formation, is associated with severe COVID-19 and long-term pulmonary sequelae. However, the clinical applications of neutrophil-targeting therapies are challenging due to short bioavailability and lack of cell-type specificity.
Methods
The lipid nanoparticle (LNP) platform designed to deliver two NET inhibitors, DNase I and Sivelestat (Siv), referred to as DPNLNPs, specifically to lung neutrophils. The LNP design was optimized by incorporating the cationic lipid into a conventional LNP formulation to enhance lung-specific delivery. To enable neutrophil targeting, Ly6G antibodies were cleaved into F(ab’)2 fragments and conjugated to the LNPs. We evaluated the therapeutic efficacy DPNLNP in the K18-hACE2 mouse model.
Results
In vitro and in vivo experiments demonstrate that DPNLNPs preferentially accumulate in the lung neutrophils and degrade NETs as efficiently as the free DNase I and Siv. Additionally, administration of DPNLNPs in K18-hACE2 mice significantly inhibited SARS-CoV-2-induced NETs at a much lower dose than the free drugs and correlated with reduced lung and systemic inflammation, lung epithelium injury, and collagen deposition. Importantly, DPNLNP treatment only during the symptomatic phase of infection improved SARS-CoV-2 outcome revealing the complex role of NETs in COVID-19 pathogenesis.
Conclusions
Together, this study serves as a proof-of-concept for adapting the LNP platform to deliver more than one immunomodulatory drug in a cell-specific manner to manage NET-associated complications in COVID-19 and other respiratory diseases.
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