Article

Functional Effects of Nanoparticle Exposure on Calu-3 Airway Epithelial Cells

Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA.
Cellular Physiology and Biochemistry (Impact Factor: 2.88). 03/2012; 29(1-2):197-212. DOI: 10.1159/000337601
Source: PubMed

ABSTRACT

High concentrations of manufactured carbon nanoparticles (CNP) are known to cause oxidative stress, inflammatory responses and granuloma formation in respiratory epithelia. To examine the effects of lower, more physiologically relevant concentrations, the human airway epithelial cell line, Calu-3, was used to evaluate potential alterations in transepithelial permeability and cellular function of airway epithelia after exposure to environmentally realistic concentrations of carbon nanoparticles. Three common carbon nanoparticles, fullerenes, single- and multi-wall carbon nanotubes (SWCNT, MWCNT) were used in these experiments. Electrophysiological measurements were performed to assay transepithelial electrical resistance (TEER) and epinephrine-stimulated chloride (Cl(-)) ion secretion of epithelial cell monolayers that had been exposed to nanoparticles for three different times (1 h, 24 h and 48 h) and over a 7 log unit range of concentrations. Fullerenes did not have any effect on the TEER or stimulated ion transport. However, the carbon nanotubes (CNT) significantly decreased TEER and inhibited epinephrine-stimulated Cl(-) secretion. The changes were time dependent and at more chronic exposures caused functional effects which were evident at concentrations substantially lower than have been previously examined. The functional changes manifested in response to physiologically relevant exposures would inhibit mucociliary clearance mechanisms and compromise the barrier function of airway epithelia.

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Available from: Frank A Witzmann, Mar 18, 2015
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    • "Decrease in the Trans-Epithelial Electrical Resistance (TEER) indicates a perturbation of the barrier function of tight epithelial monolayers, and is a parameter used to evaluate epithelial damage by MWCNT[56,55,4,57]or other nanomaterials[22]. TEER was measured using an epithelial voltmeter (EVOM, World Precision Instruments Inc., Sarasota, FL, USA). "
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    ABSTRACT: The elucidation of toxicity determinants of Multi-Walled Carbon Nanotubes (MWCNTs) is still incomplete. Functionalization with carboxyl groups is, however, commonly used to mitigate MWCNT toxicity, although the rationale for the mitigating effect has not been fully clarified yet. In this work, two optimized chemical vapor deposition methods were employed to obtain MWCNTs of comparable length but different diameter, which were subsequently functionalized. For MWCNT of diameter larger than 40 nm, no detrimental effects on cell viability of macrophages were observed, while mild cytotoxicity was recorded for diameters between 15 and 40 nm, with a mitigating effect of functionalization. To investigate the factors responsible for the mitigation, we used the thinnest MWCNT preparation on different cell models, evaluating several endpoints, such as viability, production of nitric oxide (NO), expression of pro-inflammatory markers, the Trans-Epithelial Electrical Resistance (TEER), and clonogenic activity. Substantial mitigation of the changes caused by pristine MWCNT was observed not only with carboxyl-, but also with amino-functionalized MWCNT, suggesting that negative or positive surface charge was not the main factor responsible for the effect. Instead, either functionalized preparation exhibited a stronger tendency to agglomerate that was strictly dependent on the presence of proteins. Moreover, we found that either carboxyl- or amino-functionalized MWCNT adsorbed a larger amount of serum proteins than pristine counterparts, with a distinctive pattern for each type of MWCNT. We propose, therefore, that the formation of larger agglomerates, dependent upon different protein coronae, contributes to mitigate the biological effects of functionalized MWCNT in protein-rich biological media.
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    • "These findings are consistent with our previous studies showing that 24 h exposure to the high concentration (10 μg/mL) has little effect on cell function measured as TEER. Conversely the lower concentration of CNTs (100 ng/mL) caused an approximately 40% decrease in TEER [9]. These results are also consistent with studies performed on high resistance renal epithelial cells where both TEER and hormone-stimulated ion transport showed an inverse relationship between CNT concentration and functional effect [10]. "
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