Carbon nanotubes degraded by neutrophil myeloperoxidase induce less pulmonary inflammation

• Published in: Nature nanotechnology Vol. 5; no. 5; pp. 354 - 359
• Main Authors: Kagan, Valerian E, Konduru, Nagarjun V, Feng, Weihong, Allen, Brett L, Conroy, Jennifer, Volkov, Yuri, Vlasova, Irina I, Belikova, Natalia A, Yanamala, Naveena, Kapralov, Alexander, Tyurina, Yulia Y, Shi, Jingwen, Kisin, Elena R, Murray, Ashley R, Franks, Jonathan, Stolz, Donna, Gou, Pingping, Klein-Seetharaman, Judith, Fadeel, Bengt, Star, Alexander, Shvedova, Anna A
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.05.2010; Nature Publishing Group
• Subjects: 631/250/256; 639/925/357/73; 639/925/928; 639/925/929/170; Amino acids; Animals; Biodegradation; Carbon; Chemistry and Materials Science; Enzymes; Humans; Immunoglobulin G - immunology; letter; Materials Science; Medicin och hälsovetenskap; Mice; Mice, Inbred C57BL; Models, Molecular; Nanomaterials; Nanotechnology; Nanotechnology and Microengineering; Nanotubes, Carbon - chemistry; Nanotubes, Carbon - toxicity; Nanotubes, Carbon - ultrastructure; Neutrophils; Neutrophils - drug effects; Neutrophils - enzymology; Peroxidase - metabolism; Physiology; Pneumonia - chemically induced; Pneumonia - pathology; Reactive Oxygen Species - metabolism; Spectrophotometry, Infrared; Spectrum Analysis, Raman; West Virginia; Pittsburgh Pennsylvania; United States > US; Pennsylvania
• ISSN: 1748-3387; 1748-3395; 1748-3395
• DOI: 10.1038/nnano.2010.44

We have shown previously that single-walled carbon nanotubes can be catalytically biodegraded over several weeks by the plant-derived enzyme, horseradish peroxidase 1 . However, whether peroxidase intermediates generated inside human cells or biofluids are involved in the biodegradation of carbon nanotubes has not been explored. Here, we show that hypochlorite and reactive radical intermediates of the human neutrophil enzyme myeloperoxidase catalyse the biodegradation of single-walled carbon nanotubes in vitro , in neutrophils and to a lesser degree in macrophages. Molecular modelling suggests that interactions of basic amino acids of the enzyme with the carboxyls on the carbon nanotubes position the nanotubes near the catalytic site. Importantly, the biodegraded nanotubes do not generate an inflammatory response when aspirated into the lungs of mice. Our findings suggest that the extent to which carbon nanotubes are biodegraded may be a major determinant of the scale and severity of the associated inflammatory responses in exposed individuals. A type of peroxidase enzyme found in certain white blood cells can degrade single-walled carbon nanotubes into products that do not cause inflammation in the lungs of mice, suggesting that the severity of toxic responses of carbon nanotubes may depend on the extent of its degradation.