Adenosine monophosphate is elevated in the bronchoalveolar lavage fluid of mice with acute respiratory toxicity induced by nanoparticles with high surface hydrophobicity

Abstract

Inhaled nanomaterials present a challenge to traditional methods and understanding of respiratory toxicology. In this study, a non-targeted metabolomics approach was used to investigate relationships between nanoparticle hydrophobicity, inflammatory outcomes and the metabolic fingerprint in bronchoalveolar fluid. Measures of acute lung toxicity were assessed following single-dose intratracheal administration of nanoparticles with varying surface hydrophobicity (i.e. pegylated lipid nanocapsules, polyvinyl acetate nanoparticles and polystyrene beads; listed in order of increasing hydrophobicity). Broncho-alveolar lavage (BAL) fluid was collected from mice exposed to nanoparticles at a surface area dose of 220 cm(2) and metabolite fingerprints were acquired via ultra pressure liquid chromatography-mass spectrometry-based metabolomics. Particles with high surface hydrophobicity were pro-inflammatory. Multivariate analysis of the resultant small molecule fingerprints revealed clear discrimination between the vehicle control and polystyrene beads (p < 0.05), as well as between nanoparticles of different surface hydrophobicity (p < 0.0001). Further investigation of the metabolic fingerprints revealed that adenosine monophosphate (AMP) concentration in BAL correlated with neutrophilia (p < 0.01), CXCL1 levels (p < 0.05) and nanoparticle surface hydrophobicity (p < 0.001). Our results suggest that extracellular AMP is an intermediary metabolite involved in adenine nucleotide-regulated neutrophilic inflammation as well as tissue damage, and could potentially be used to monitor nanoparticle-induced responses in the lung following pulmonary administration.

Lung inflammation does not affect the clearance kinetics of lipid nanocapsules following pulmonary administration

“…Similar to previously published reports [15,16], lipid nanocapsule administration to the healthy lung was well tolerated. Importantly, nanocapsule administration to a murine model of neutrophilic airway inflammation did not to exacerbate the pre-existing inflammatory condition.…”

“…procedure did not induce acute inflammation in healthy lungs (Fig. 1B-D), thus confirming previous findings [15,16]. Histological analysis of lung tissue showed an accumulation of neutrophils in the lungs obtained from mice pre-treated with LPS ( Fig.…”

“…Nanocapsules were diluted 1:50 in purified water or saline and measurements taken at 25°C for quality control, at a scattering angle of 173°, using a viscosity value of water (0.8872 cP) for the dispersant. While all nanocapsule suspensions were size-stable for over four weeks when stored in purified water at 4°C [16], fresh batches were prepared for each in vivo experiment and used within 7 days of manufacture. Zeta potential measurements were performed at 25°C at a concentration of 20 μg/mL with all suspensions diluted in 6.3 mM NaCl aq .…”

“…Lipid nanocapsules can be manufactured on an industrial scale, exhibit long storage shelf-lives in suspension, demonstrate a high stability during nebulisation [9,12] and achieve constant, reproducible drug release profiles [13,14]. Furthermore, lipid nanocapsules have shown an excellent in vivo biocompatibility profile following single pulmonary administration across a range of therapeutically relevant doses [15,16] and are not associated with acute adverse macrophage responses [15].…”

Absence of lung fibrosis after a single pulmonary delivery of lipid nanocapsules in rats

“…Results confirm that particles with high surface hydrophobicity were proinflammatory and that adenosine monophosphate (AMP) concentration in bronchoalveolar fluid was correlated with neutrophilia and nanoparticle surface hydrophobicity. 17 Grabowski et al, 18 in a model of human respiratory alveolar epithelium cell culture, have clearly demonstrated that the inflammation and cell damage induced by these vectors are correlated with the surface charge and the nature of the nanoparticle core.…”