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Alternative Title:figshare Academic Research System
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Journal Article:Nanotoxicology
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Corporate Authors:National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Receptor Biology Laboratory, Toxicology Molecular Biology Branch, Health Effects Lab. Division ; Receptor Biology Laboratory, Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention
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Description:Pulmonary exposure to carbon nanotubes (CNTs) induces fibrosing lesions in the lungs that manifest rapid-onset inflammatory and fibrotic responses, leading to chronic fibrosis in animals and health concerns in exposed humans. The mechanisms underlying CNT-induced fibrogenic effects remain undefined. Macrophages are known to play important roles in immune regulation and fibrosis development through their distinct subsets. Here we investigated macrophage polarization and activation in mouse lungs exposed to multi-walled CNTs (MWCNTs). Male C57BL/6J mice were treated with MWCNTs (XNRI MWNT-7) at 40 μg per mouse (∼1.86 mg/kg body weight) by oropharyngeal aspiration. The treatment stimulated prominent acute inflammatory and fibrotic responses. Moreover, it induced pronounced enrichment and polarization of macrophages with significantly increased M1 and M2 populations in a time-dependent manner. Induction of M1 polarization was apparent on day 1 with a peak on day 3, but declined rapidly thereafter. On the other hand, the M2 polarization was induced on day 1 modestly, but was remarkably elevated on day 3 and maintained at a high level through day 7. M1 and M2 macrophages were functionally activated by MWCNTs as indicated by the expression of their distinctive functional markers, such as iNOS and ARG1, with time courses parallel to M1 and M2 polarization, respectively. Molecular analysis revealed MWCNTs boosted specific STAT and IRF signaling pathways to regulate M1 and M2 polarization in the lungs. These findings suggest a new mechanistic connection between inflammation and fibrosis induced by MWCNTs through the polarization and activation of macrophages during MWCNT-induced lung pathologic response.
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Content Notes:Stacks:76923
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Modified:01/17/2018
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Date Issued:01/01/2018
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