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Toxicity evaluation of manufactured CeO2 nanoparticles before and after alteration: combined physicochemical and whole-genome expression analysis in Caco-2 cells.

Fisichella M, Berenguer F, Steinmetz G, Auffan M, Rose J, Prat O - BMC Genomics (2014)

Bottom Line: Gene expression profiles obtained from cells exposed to NPs before and after their alteration were compared, to highlight differences in cellular functions.No change in the cerium redox state was observed for altered NPs.Conversely, Nanobyk 3810™ coated with ammonium citrate did not display any adverse effect at the same concentration.It can be assumed that the safe design of engineered nanoparticles could include robust protective layers conferring on them greater resistance to alteration during their life cycle.

View Article: PubMed Central - PubMed

Affiliation: CEA, IBEB, SBTN, Laboratoire d'Etude des Protéines Cibles, F-30207 Bagnols-sur-Cèze, France. odette.prat@cea.fr.

ABSTRACT

Background: Engineered nanomaterials may release nanosized residues, by degradation, throughout their life cycle. These residues may be a threat for living organisms. They may be ingested by humans through food and water. Although the toxicity of pristine CeO2 nanoparticles (NPs) has been documented, there is a lack of studies on manufactured nanoparticles, which are often surface modified. Here, we investigated the potential adverse effects of CeO2 Nanobyk 3810™ NPs, used in wood care, and their residues, altered by light or acid.

Results: Human intestinal Caco-2 cells were exposed to residues degraded by daylight or in a medium simulating gastric acidity. Size and zeta potential were determined by dynamic light scattering. The surface structure and redox state of cerium were analyzed by transmission electronic microscopy (TEM) and X-ray absorption spectroscopy, respectively. Viability tests were performed in Caco-2 cells exposed to NPs. Cell morphology was imaged with scanning electronic microscopy. Gene expression profiles obtained from cells exposed to NPs before and after their alteration were compared, to highlight differences in cellular functions.No change in the cerium redox state was observed for altered NPs. All CeO2 NPs suspended in the culture medium became microsized. Cytotoxicity tests showed no toxicity after Caco-2 cell exposure to these various NPs up to 170 μg/mL (24 h and 72 h). Nevertheless, a more-sensitive whole-gene-expression study, based on a pathway-driven analysis, highlighted a modification of metabolic activity, especially mitochondrial function, by altered Nanobyk 3810™. The down-regulation of key genes of this pathway was validated by qRT-PCR. Conversely, Nanobyk 3810™ coated with ammonium citrate did not display any adverse effect at the same concentration.

Conclusion: The degraded nanoparticles were more toxic than their coated counterparts. Desorption of the outside layer was the most likely cause of this discrepancy in toxicity. It can be assumed that the safe design of engineered nanoparticles could include robust protective layers conferring on them greater resistance to alteration during their life cycle.

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Related in: MedlinePlus

Complexes of the respiratory chain altered by degraded Nanobyk. Pristine CeO2 under-expressed 27 genes encoding subunits of complex I, III ( cytochrome b-c1), IV and V. Acid-degraded Nanobyk downregulated 10 genes encoding subunits of complex I (NADH dehydrogenase), complex II (succinate dehydrogenase), complex IV (cytochrome c oxidase) and complex V (ATP synthase). Light-degraded Nanobyk down regulated 3 genes encoding subunits of complexes II and IV. Nanobyk NPs did not alter the respiratory chain. Differentially expressed genes belonging to this specific pathway are listed in Table 2.
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Fig6: Complexes of the respiratory chain altered by degraded Nanobyk. Pristine CeO2 under-expressed 27 genes encoding subunits of complex I, III ( cytochrome b-c1), IV and V. Acid-degraded Nanobyk downregulated 10 genes encoding subunits of complex I (NADH dehydrogenase), complex II (succinate dehydrogenase), complex IV (cytochrome c oxidase) and complex V (ATP synthase). Light-degraded Nanobyk down regulated 3 genes encoding subunits of complexes II and IV. Nanobyk NPs did not alter the respiratory chain. Differentially expressed genes belonging to this specific pathway are listed in Table 2.

Mentions: Comparison of the common canonical pathways disturbed by pristine CeO2 NPs and degraded NB NPs essentially showed that they all disturbed mitochondrial functions and the oxidative phosphorylation pathway. Oxidative phosphorylation is the mitochondrial process by which ATP is formed as a result of the transfer of electrons from NADH or FADH2 through a series of electron carriers to oxygen. Consequently, this pathway is modified as a result of mitochondrial dysfunction (Figure 6). The downregulation of some key genes of oxidative phosphorylation was validated by qRT-PCR (Table 3).Figure 6


Toxicity evaluation of manufactured CeO2 nanoparticles before and after alteration: combined physicochemical and whole-genome expression analysis in Caco-2 cells.

Fisichella M, Berenguer F, Steinmetz G, Auffan M, Rose J, Prat O - BMC Genomics (2014)

Complexes of the respiratory chain altered by degraded Nanobyk. Pristine CeO2 under-expressed 27 genes encoding subunits of complex I, III ( cytochrome b-c1), IV and V. Acid-degraded Nanobyk downregulated 10 genes encoding subunits of complex I (NADH dehydrogenase), complex II (succinate dehydrogenase), complex IV (cytochrome c oxidase) and complex V (ATP synthase). Light-degraded Nanobyk down regulated 3 genes encoding subunits of complexes II and IV. Nanobyk NPs did not alter the respiratory chain. Differentially expressed genes belonging to this specific pathway are listed in Table 2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4150968&req=5

Fig6: Complexes of the respiratory chain altered by degraded Nanobyk. Pristine CeO2 under-expressed 27 genes encoding subunits of complex I, III ( cytochrome b-c1), IV and V. Acid-degraded Nanobyk downregulated 10 genes encoding subunits of complex I (NADH dehydrogenase), complex II (succinate dehydrogenase), complex IV (cytochrome c oxidase) and complex V (ATP synthase). Light-degraded Nanobyk down regulated 3 genes encoding subunits of complexes II and IV. Nanobyk NPs did not alter the respiratory chain. Differentially expressed genes belonging to this specific pathway are listed in Table 2.
Mentions: Comparison of the common canonical pathways disturbed by pristine CeO2 NPs and degraded NB NPs essentially showed that they all disturbed mitochondrial functions and the oxidative phosphorylation pathway. Oxidative phosphorylation is the mitochondrial process by which ATP is formed as a result of the transfer of electrons from NADH or FADH2 through a series of electron carriers to oxygen. Consequently, this pathway is modified as a result of mitochondrial dysfunction (Figure 6). The downregulation of some key genes of oxidative phosphorylation was validated by qRT-PCR (Table 3).Figure 6

Bottom Line: Gene expression profiles obtained from cells exposed to NPs before and after their alteration were compared, to highlight differences in cellular functions.No change in the cerium redox state was observed for altered NPs.Conversely, Nanobyk 3810™ coated with ammonium citrate did not display any adverse effect at the same concentration.It can be assumed that the safe design of engineered nanoparticles could include robust protective layers conferring on them greater resistance to alteration during their life cycle.

View Article: PubMed Central - PubMed

Affiliation: CEA, IBEB, SBTN, Laboratoire d'Etude des Protéines Cibles, F-30207 Bagnols-sur-Cèze, France. odette.prat@cea.fr.

ABSTRACT

Background: Engineered nanomaterials may release nanosized residues, by degradation, throughout their life cycle. These residues may be a threat for living organisms. They may be ingested by humans through food and water. Although the toxicity of pristine CeO2 nanoparticles (NPs) has been documented, there is a lack of studies on manufactured nanoparticles, which are often surface modified. Here, we investigated the potential adverse effects of CeO2 Nanobyk 3810™ NPs, used in wood care, and their residues, altered by light or acid.

Results: Human intestinal Caco-2 cells were exposed to residues degraded by daylight or in a medium simulating gastric acidity. Size and zeta potential were determined by dynamic light scattering. The surface structure and redox state of cerium were analyzed by transmission electronic microscopy (TEM) and X-ray absorption spectroscopy, respectively. Viability tests were performed in Caco-2 cells exposed to NPs. Cell morphology was imaged with scanning electronic microscopy. Gene expression profiles obtained from cells exposed to NPs before and after their alteration were compared, to highlight differences in cellular functions.No change in the cerium redox state was observed for altered NPs. All CeO2 NPs suspended in the culture medium became microsized. Cytotoxicity tests showed no toxicity after Caco-2 cell exposure to these various NPs up to 170 μg/mL (24 h and 72 h). Nevertheless, a more-sensitive whole-gene-expression study, based on a pathway-driven analysis, highlighted a modification of metabolic activity, especially mitochondrial function, by altered Nanobyk 3810™. The down-regulation of key genes of this pathway was validated by qRT-PCR. Conversely, Nanobyk 3810™ coated with ammonium citrate did not display any adverse effect at the same concentration.

Conclusion: The degraded nanoparticles were more toxic than their coated counterparts. Desorption of the outside layer was the most likely cause of this discrepancy in toxicity. It can be assumed that the safe design of engineered nanoparticles could include robust protective layers conferring on them greater resistance to alteration during their life cycle.

Show MeSH
Related in: MedlinePlus