title: Mechanism of uptake of ZnO nanoparticles and inflammatory responses in macrophages require PI3K mediated MAPKs signaling.
abstract: The inflammatory responses after exposure to zinc oxide nanoparticles (ZNPs) are known, however, the molecular mechanisms and direct consequences of particle uptake are still unclear. Dose and time-dependent increase in the uptake of ZNPs by macrophages has been observed by flow cytometry. Macrophages treated with ZNPs showed a significantly enhanced phagocytic activity. Inhibition of different internalization receptors caused a reduction in uptake of ZNPs in macrophages. The strongest inhibition in internalization was observed by blocking clathrin, caveolae and scavenger receptor mediated endocytic pathways. However, FcR and complement receptor-mediated phagocytic pathways also contributed significantly to control. Further, exposure of primary macrophages to ZNPs (2.5 μg/ml) caused (i) significant enhancement of Ras, PI3K, (ii) enhanced phosphorylation and subsequent activation of its downstream signaling pathways via ERK1/2, p38 and JNK MAPKs (iii) overexpression of c-Jun, c-Fos and NF-κB. Our results demonstrate that ZNPs induce the generation of reactive nitrogen species and overexpression of Cox-2, iNOS, pro-inflammatory cytokines (IL-6, IFN-γ, TNF-α, IL-17 and regulatory cytokine IL-10) and MAPKs which were found to be inhibited after blocking internalization of ZNPs through caveolae receptor pathway. These results indicate that ZNPs are internalized through caveolae pathway and the inflammatory responses involve PI3K mediated MAPKs signaling cascade.
authors.affiliation: Food, Drug and Chemical Toxicology Group, Indian Institute of Toxicology Research, M.G. Marg, Post Box No. 80, Lucknow 226001, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India.
authors.forename: Ruchi
authors.initials: R
authors.lastname: Roy
authors.affiliation: Nanotechnology Application Centre, Faculty of Science, University of Allahabad, Allahabad 211002, India.
authors.forename: Vyom
authors.initials: V
authors.lastname: Parashar
authors.affiliation: Electron Microscopy Facility, CSIR-Indian Institute of Toxicology Research, M.G. Marg, Post Box No. 80, Lucknow 226001, India.
authors.forename: L K S
authors.initials: LK
authors.lastname: Chauhan
authors.affiliation: Food, Drug and Chemical Toxicology Group, Indian Institute of Toxicology Research, M.G. Marg, Post Box No. 80, Lucknow 226001, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India; Environmental Toxicology Division, CSIR-Indian Institute of Toxicology Research, M.G. Marg, Post Box No. 80, Lucknow 226001, India.
authors.forename: Rishi
authors.initials: R
authors.lastname: Shanker
authors.affiliation: Food, Drug and Chemical Toxicology Group, Indian Institute of Toxicology Research, M.G. Marg, Post Box No. 80, Lucknow 226001, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India.
authors.forename: Mukul
authors.initials: M
authors.lastname: Das
authors.affiliation: Food, Drug and Chemical Toxicology Group, Indian Institute of Toxicology Research, M.G. Marg, Post Box No. 80, Lucknow 226001, India. Electronic address: anurag1706@gmail.com.
authors.forename: Anurag
authors.initials: A
authors.lastname: Tripathi
authors.affiliation: Food, Drug and Chemical Toxicology Group, Indian Institute of Toxicology Research, M.G. Marg, Post Box No. 80, Lucknow 226001, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India. Electronic address: pddwivedi@iitr.res.in.
authors.forename: Premendra Dhar
authors.initials: PD
authors.lastname: Dwivedi
mesh_terms: D000818:Animals; D021941:Caveolae / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D007249:Inflammation / Q000139:chemically induced* / Q000473:pathology; D008264:Macrophages / Q000187:drug effects* / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D053758:Nanoparticles; D010587:Phagocytosis / Q000187:drug effects; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D015034:Zinc Oxide / Q000008:administration & dosage / Q000378:metabolism / Q000633:toxicity*
chemical_list: D016207:Cytokines; D019869:Phosphatidylinositol 3-Kinases; D020928:Mitogen-Activated Protein Kinases; D015034:Zinc Oxide
keywords: Endocytosis; Macrophages; Phagocytosis; Proinflammatory cytokines; Zinc oxide nanoparticles