Immunotoxicity of engineered nanomaterials and their role in asthma.

The toxicity of engineered nanomaterials (ENMs) in vivo and in vitro has formed the basis of most studies. However, the toxicity of ENMs, particularly on the immune system, i.e. immunotoxicity, and their role in manipulating it, are less known. This review addresses the initiation or exacerbation as well as the attenuation of allergic asthma by a variety of ENMs and how they may be used in drug delivery to enhance the treatment of asthma. This review also highlights a few research gaps in the study of the immunotoxicity of ENMs, for example, the potential drawbacks of assays used in immunotoxicity assays; the potential role of hormesis during dosing of ENMs; and the variables that result in discrepancies among different studies, such as the physicochemical properties of ENMs, differences in asthmatic animal models, and different routes of administration. Abbreviations: AHR: airway hyperresponsiveness; ALI: air-lung epithelium interface; BDP: beclometasone dipropionate; CB: carbon black; CNTs: carbon nanotubes; CpG: cytosine linked through a phosphodiester to guanine; EGFR: epidermal growth factor receptor; ENMs: engineered nanomaterials; GLA: gut--lung axis; Ig: immunoglobulin; IL: interleukin; LC: liquid crystalline; LLNA: local lymph node assay; LPS: lipopolysaccharide; MWCNTs: multi-walled CNTs; NPs: nanoparticles; OVA: ovalbumin; PAMAM: polyamidoamine; PFC: plaque-forming cell; PM: particulate matter; ROS: reactive oxygen species; SBS: salbutamol sulfate; SWCNTs: single-walled CNTs; TDI: toluene diisocyanate; VEGF: vascular endothelial growth factor [ABSTRACT FROM AUTHOR]