Peptide targeting and imaging of damaged lung tissue in influenza-infected mice

Abstract

In this study, we investigate whether pH (low) insertion peptide (pHLIP) can target regions of lung injury associated with influenza infection. Materials & methods: Fluorophore-conjugated pHLIP was injected intraperitoneally into mice infected with a sublethal dose of H1N1 influenza and visualized histologically. Results: pHLIP specifically targeted inflamed lung tissues of infected mice in the later stages of disease and at sites where alveolar type I and type II cells were depleted. Regions of pHLIP-targeted lung tissue were devoid of peroxiredoxin 6, the lung-abundant antioxidant enzyme, and were deficient in pneumocytes. Interestingly, a pHLIP variant possessing mutations that render it insensitive to pH changes was also able to target damaged lung tissue. Conclusion: pHLIP holds potential for delivering therapeutics for lung injury during influenza infection. Furthermore, there may be more than one mechanism that enables pHLIP variants to target inflamed lung tissue.