A flow cytometric analysis of macrophage- nanoparticle interactions in vitro: induction of altered Toll-like receptor expression

• Published in: International journal of nanomedicine 2018-01, Vol.13, p.8365-8378
• Main Authors: Njoroge, Joyce M, Yourick, Jeffrey J, Principato, Mary Ann
• Format: Article
• Language: English
• Subjects: Analysis; Animals; Apoptosis; Cell cycle; Citric Acid - pharmacology; Dendritic cells; Deoxyribonucleic acid; DNA; Experiments; Flow cytometry; Flow Cytometry - methods; Fluorescence; Food; Hydrodynamics; innate immunity; Kinases; macrophage; Macrophages; Macrophages - drug effects; Macrophages - metabolism; Mice; Nanoparticles; Nanoparticles - chemistry; Nanoparticles - ultrastructure; Nanotechnology; Original Research; Oxidative stress; Particle Size; Povidone; RAW 264.7 Cells; Silver; Silver - pharmacology; Silver Nanoparticle; toll receptor; Toll-Like Receptors - metabolism
• ISSN: 1178-2013; 1176-9114; 1178-2013
• DOI: 10.2147/IJN.S174184

Nanoparticles exhibit unique physiochemical characteristics that provide the basis for their utilization. The diversity of potential and actual applications compels a thorough understanding regarding the consequences of their containment within the cellular environment. This paper presents a flow cytometric examination of the biologic effects associated with the internalization of citrate-buffered silver (Ag) nanoparticles (NP) by the murine macrophage cell line, RAW264.7. Cells were cultured with varying concentrations of citrate-buffered Ag nanoparticle and analyzed for changes in cellular volume, fluorescence emissions, and surface receptor expression. Notable changes in side scatter (SSC) signal occurred following the phagocytosis of citrate-buffered Ag NP representative of the 10 nm, 50 nm, and 100 nm particle size by cultured RAW 264.7 cells. A characteristic associated with the internalization of all the citrated Ag NP sizes tested, was the detection of emitted infra-red and near-infrared wavelength emissions. This characteristic consistently permitted the detection of 10 nm, 50 nm, and 100 nm Ag NP particles internalized within the RAW cells by flow cytometry. A functional distinction between monocyte subsets within the RAW 264.7 cell line was noted as Ag NP are taken up by the F4/80+ subset of cells within the culture. Further, the internalization of Ag NP by the cells resulted in an increased cell surface expression of the Toll-like receptor (TLR) 3, but not TLR4. Taken together, these results implicate the more mature macrophage in the ingestion of Ag NP; and an influence upon at least one of the Toll receptors present in macrophages following exposure to Ag NP. Further, our flow cytometric approach presents a potentially viable detection method for the identification of occult Ag NP material using an indicator cell line.