title: Surfactant protein A (SP-A) inhibits agglomeration and macrophage uptake of toxic amine modified nanoparticles.
abstract: The lung provides the main route for nanomaterial exposure. Surfactant protein A (SP-A) is an important respiratory innate immune molecule with the ability to bind or opsonise pathogens to enhance phagocytic removal from the airways. We hypothesised that SP-A, like surfactant protein D, may interact with inhaled nanoparticulates, and that this interaction will be affected by nanoparticle (NP) surface characteristics. In this study, we characterise the interaction of SP-A with unmodified (U-PS) and amine-modified (A-PS) polystyrene particles of varying size and zeta potential using dynamic light scatter analysis. SP-A associated with both 100 nm U-PS and A-PS in a calcium-independent manner. SP-A induced significant calcium-dependent agglomeration of 100 nm U-PS NPs but resulted in calcium-independent inhibition of A-PS self agglomeration. SP-A enhanced uptake of 100 nm U-PS into macrophage-like RAW264.7 cells in a dose-dependent manner but in contrast inhibited A-PS uptake. Reduced association of A-PS particles in RAW264.7 cells following pre-incubation of SP-A was also observed with coherent anti-Stokes Raman spectroscopy. Consistent with these findings, alveolar macrophages (AMs) from SP-A(-/-) mice were more efficient at uptake of 100 nm A-PS compared with wild type C57Bl/6 macrophages. No difference in uptake was observed with 500 nm U-PS or A-PS particles. Pre-incubation with SP-A resulted in a significant decrease in uptake of 100 nm A-PS in macrophages isolated from both groups of mice. In contrast, increased uptake by AMs of U-PS was observed after pre-incubation with SP-A. Thus we have demonstrated that SP-A promotes uptake of non-toxic U-PS particles but inhibits the clearance of potentially toxic A-PS particles by blocking uptake into macrophages.
authors: a Department of Child Health, Clinical and Experimental Sciences, Faculty of Medicine , Southampton General Hospital, University of Southampton , Southampton , UK .
authors: Zofi
authors: Z
authors: McKenzie
authors: a Department of Child Health, Clinical and Experimental Sciences, Faculty of Medicine , Southampton General Hospital, University of Southampton , Southampton , UK .|b School of Geography, Earth and Environmental Sciences, University of Birmingham , Birmingham , UK .
authors: Michaela
authors: M
authors: Kendall
authors: a Department of Child Health, Clinical and Experimental Sciences, Faculty of Medicine , Southampton General Hospital, University of Southampton , Southampton , UK .
authors: Rose-Marie
authors: RM
authors: Mackay
authors: a Department of Child Health, Clinical and Experimental Sciences, Faculty of Medicine , Southampton General Hospital, University of Southampton , Southampton , UK .
authors: Harry
authors: H
authors: Whitwell
authors: b School of Geography, Earth and Environmental Sciences, University of Birmingham , Birmingham , UK .
authors: Christine
authors: C
authors: Elgy
authors: c Facility for Environmental Nanoscience Analysis and Characterisation (FENAC), School of Metallurgy and Materials, University of Birmingham , Birmingham , UK .
authors: Ping
authors: P
authors: Ding
authors: d Institute for Life Sciences, University of Southampton , Highfield , Southampton , UK .|e Department of Chemistry , University of Southampton , Highfield , Southampton , UK .
authors: Sumeet
authors: S
authors: Mahajan
authors: f Leukocyte Biology, Royal Brompton Campus, Imperial College London , London , UK , and.
authors: Cliff
authors: C
authors: Morgan
authors: f Leukocyte Biology, Royal Brompton Campus, Imperial College London , London , UK , and.
authors: Mark
authors: M
authors: Griffiths
authors: a Department of Child Health, Clinical and Experimental Sciences, Faculty of Medicine , Southampton General Hospital, University of Southampton , Southampton , UK .|d Institute for Life Sciences, University of Southampton , Highfield , Southampton , UK .|g National Institute for Health Research, Southampton Respiratory Biomedical Research Unit, Southampton Centre for Biomedical Research, University Hospital Southampton NHS Foundation Trust , Southampton , UK.
authors: Howard
authors: H
authors: Clark
authors: a Department of Child Health, Clinical and Experimental Sciences, Faculty of Medicine , Southampton General Hospital, University of Southampton , Southampton , UK .|d Institute for Life Sciences, University of Southampton , Highfield , Southampton , UK .|g National Institute for Health Research, Southampton Respiratory Biomedical Research Unit, Southampton Centre for Biomedical Research, University Hospital Southampton NHS Foundation Trust , Southampton , UK.
authors: Jens
authors: J
authors: Madsen
mesh_terms: D000280:Administration, Inhalation; D000588:Amines / Q000737:chemistry* / Q000633:toxicity; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006801:Humans; D016676:Macrophages, Alveolar / Q000187:drug effects* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053758:Nanoparticles / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity*; D010316:Particle Size; D010587:Phagocytosis / Q000187:drug effects; D011137:Polystyrenes / Q000737:chemistry / Q000633:toxicity; D037662:Pulmonary Surfactant-Associated Protein A / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000588:Amines; D011137:Polystyrenes; D037662:Pulmonary Surfactant-Associated Protein A
keywords: Collectin; mucosal; nanoparticles; surface chemistry; surfactant