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Modulation of apoptotic pathways of macrophages by surface-functionalized multi-walled carbon nanotubes.

Jiang Y, Zhang H, Wang Y, Chen M, Ye S, Hou Z, Ren L - PLoS ONE (2013)

Bottom Line: However, the potential adverse effects of surface-functionalized CNTs have not been well characterized.The less cytotoxic and apoptotic effect of MWCNTs-PEG compared with MWCNTs-COOH resulted from the lower cellular uptake of MWCNTs-PEG, which resulted in less activation of oxidative stress-responsive pathways, such as p38 mitogen-activated protein kinases (MAPK) and nuclear factor (NF)-κB.These results demonstrate that surface functionalization of CNTs may alter ROS-mediated cytotoxic and apoptotic response by modulating apoptotic signaling pathways.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomaterials, College of Materials, Xiamen University, Xiamen, China.

ABSTRACT
Biomedical applications of carbon nanotubes (CNTs) often involve improving their hydrophilicity and dispersion in biological media by modifying them through noncovalent or covalent functionalization. However, the potential adverse effects of surface-functionalized CNTs have not been well characterized. In this study, we functionalized multi-walled CNTs (MWCNTs) via carboxylation, to produce MWCNTs-COOH, and via poly (ethylene glycol) linking, to produce MWCNTs-PEG. We used these functionalized MWCNTs to study the effect of surface functionalization on MWCNTs-induced toxicity to macrophages, and elucidate the underlying mechanisms of action. Our results revealed that MWCNTs-PEG were less cytotoxic and were associated with less apoptotic cell death of macrophages than MWCNTs-COOH. Additionally, MWCNTs-PEG induced less generation of reactive oxygen species (ROS) involving less activation of NADPH oxidase compared with MWCNTs-COOH, as evidenced by membrane translocation of p47(phox) and p67(phox) in macrophages. The less cytotoxic and apoptotic effect of MWCNTs-PEG compared with MWCNTs-COOH resulted from the lower cellular uptake of MWCNTs-PEG, which resulted in less activation of oxidative stress-responsive pathways, such as p38 mitogen-activated protein kinases (MAPK) and nuclear factor (NF)-κB. These results demonstrate that surface functionalization of CNTs may alter ROS-mediated cytotoxic and apoptotic response by modulating apoptotic signaling pathways. Our study thus provides new insights into the molecular basis for the surface properties affecting CNTs toxicity.

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Involvement of NADPH oxidase, ROS, p38 MAPK, and NF-κB in MWCNTs-COOH- and MWCNTs-PEG-induced apoptosis of RAW264.7 cells.Cells were pretreated with a ROS scavenger (NAC), NADPH oxidase inhibitor (DPI), p38 inhibitor (SB203580), or NF-κB inhibitor (PDTC) for 1 h, and then treated with either MWCNTs-COOH or MWCNTs-PEG for 24 h. Western blot analysis and DCF staining using flow cytometry were used to determine levels of cytoplasmic p65 (A) and intracellular ROS (B), then the apoptosis of RAW264.7 cells were evaluated by flow cytometry using PI staining. Data are representative of three independent experiments (C). *p<0.05 compared to control sample.
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pone-0065756-g011: Involvement of NADPH oxidase, ROS, p38 MAPK, and NF-κB in MWCNTs-COOH- and MWCNTs-PEG-induced apoptosis of RAW264.7 cells.Cells were pretreated with a ROS scavenger (NAC), NADPH oxidase inhibitor (DPI), p38 inhibitor (SB203580), or NF-κB inhibitor (PDTC) for 1 h, and then treated with either MWCNTs-COOH or MWCNTs-PEG for 24 h. Western blot analysis and DCF staining using flow cytometry were used to determine levels of cytoplasmic p65 (A) and intracellular ROS (B), then the apoptosis of RAW264.7 cells were evaluated by flow cytometry using PI staining. Data are representative of three independent experiments (C). *p<0.05 compared to control sample.

Mentions: To determine the causal relationship between apoptosis and ROS, p38 MAPK, or NF-κB RAW 264.7 cells were treated with either MWCNTs-COOH or MWCNTs-PEG for 24 h with or without addition of an inhibitor of ROS (NAC), NADPH oxidase (DPI), NF-κB (PDTC), or p38 MAPK (SB203580). Figure 11A and B demonstrates that pretreatment of RAW264.7 cells with NAC, DPI, or PDTC inhibited ROS accumulation and NF-κB activation. As shown in Figure 11C, these specific inhibitors significantly suppressed apoptosis induced by MWCNTs-COOH and MWCNTs-PEG. These findings indicated that MWCNTs-COOH- and MWCNTs-PEG-induced apoptosis depended in part on NADPH oxidase-driven ROS, p38 MAPK, and NF-κB pathways.


Modulation of apoptotic pathways of macrophages by surface-functionalized multi-walled carbon nanotubes.

Jiang Y, Zhang H, Wang Y, Chen M, Ye S, Hou Z, Ren L - PLoS ONE (2013)

Involvement of NADPH oxidase, ROS, p38 MAPK, and NF-κB in MWCNTs-COOH- and MWCNTs-PEG-induced apoptosis of RAW264.7 cells.Cells were pretreated with a ROS scavenger (NAC), NADPH oxidase inhibitor (DPI), p38 inhibitor (SB203580), or NF-κB inhibitor (PDTC) for 1 h, and then treated with either MWCNTs-COOH or MWCNTs-PEG for 24 h. Western blot analysis and DCF staining using flow cytometry were used to determine levels of cytoplasmic p65 (A) and intracellular ROS (B), then the apoptosis of RAW264.7 cells were evaluated by flow cytometry using PI staining. Data are representative of three independent experiments (C). *p<0.05 compared to control sample.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3675050&req=5

pone-0065756-g011: Involvement of NADPH oxidase, ROS, p38 MAPK, and NF-κB in MWCNTs-COOH- and MWCNTs-PEG-induced apoptosis of RAW264.7 cells.Cells were pretreated with a ROS scavenger (NAC), NADPH oxidase inhibitor (DPI), p38 inhibitor (SB203580), or NF-κB inhibitor (PDTC) for 1 h, and then treated with either MWCNTs-COOH or MWCNTs-PEG for 24 h. Western blot analysis and DCF staining using flow cytometry were used to determine levels of cytoplasmic p65 (A) and intracellular ROS (B), then the apoptosis of RAW264.7 cells were evaluated by flow cytometry using PI staining. Data are representative of three independent experiments (C). *p<0.05 compared to control sample.
Mentions: To determine the causal relationship between apoptosis and ROS, p38 MAPK, or NF-κB RAW 264.7 cells were treated with either MWCNTs-COOH or MWCNTs-PEG for 24 h with or without addition of an inhibitor of ROS (NAC), NADPH oxidase (DPI), NF-κB (PDTC), or p38 MAPK (SB203580). Figure 11A and B demonstrates that pretreatment of RAW264.7 cells with NAC, DPI, or PDTC inhibited ROS accumulation and NF-κB activation. As shown in Figure 11C, these specific inhibitors significantly suppressed apoptosis induced by MWCNTs-COOH and MWCNTs-PEG. These findings indicated that MWCNTs-COOH- and MWCNTs-PEG-induced apoptosis depended in part on NADPH oxidase-driven ROS, p38 MAPK, and NF-κB pathways.

Bottom Line: However, the potential adverse effects of surface-functionalized CNTs have not been well characterized.The less cytotoxic and apoptotic effect of MWCNTs-PEG compared with MWCNTs-COOH resulted from the lower cellular uptake of MWCNTs-PEG, which resulted in less activation of oxidative stress-responsive pathways, such as p38 mitogen-activated protein kinases (MAPK) and nuclear factor (NF)-κB.These results demonstrate that surface functionalization of CNTs may alter ROS-mediated cytotoxic and apoptotic response by modulating apoptotic signaling pathways.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomaterials, College of Materials, Xiamen University, Xiamen, China.

ABSTRACT
Biomedical applications of carbon nanotubes (CNTs) often involve improving their hydrophilicity and dispersion in biological media by modifying them through noncovalent or covalent functionalization. However, the potential adverse effects of surface-functionalized CNTs have not been well characterized. In this study, we functionalized multi-walled CNTs (MWCNTs) via carboxylation, to produce MWCNTs-COOH, and via poly (ethylene glycol) linking, to produce MWCNTs-PEG. We used these functionalized MWCNTs to study the effect of surface functionalization on MWCNTs-induced toxicity to macrophages, and elucidate the underlying mechanisms of action. Our results revealed that MWCNTs-PEG were less cytotoxic and were associated with less apoptotic cell death of macrophages than MWCNTs-COOH. Additionally, MWCNTs-PEG induced less generation of reactive oxygen species (ROS) involving less activation of NADPH oxidase compared with MWCNTs-COOH, as evidenced by membrane translocation of p47(phox) and p67(phox) in macrophages. The less cytotoxic and apoptotic effect of MWCNTs-PEG compared with MWCNTs-COOH resulted from the lower cellular uptake of MWCNTs-PEG, which resulted in less activation of oxidative stress-responsive pathways, such as p38 mitogen-activated protein kinases (MAPK) and nuclear factor (NF)-κB. These results demonstrate that surface functionalization of CNTs may alter ROS-mediated cytotoxic and apoptotic response by modulating apoptotic signaling pathways. Our study thus provides new insights into the molecular basis for the surface properties affecting CNTs toxicity.

Show MeSH
Related in: MedlinePlus