Toxicity of carboxylated carbon nanotubes in endothelial cells is attenuated by stimulation of the autophagic flux with the release of nanomaterial in autophagic vesicles

Orečná, Martina; Paoli, Silvia H. De; Janoušková, Olga; Tegegn, Tseday Z.; Filipová, Marcela; Bonevich, John E.; Holada, Karel; Šimák, Jan

doi:10.1016/j.nano.2014.02.001

Cited by 63 publications

(38 citation statements)

References 37 publications

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“…Lysosomes also play an important role in the degradation of engulfed particles, and nanoparticle exposure may impair the fusion of autophagosomes with lysosomes (Stern et al, 2012). A recent study showed that carbon nanotube exposure induced autophagosome accumulation due to a blockade of the autophagic flux, whereas pharmacological stimulation of the autophagic flux promoted extracellular efflux of nanoparticles and attenuated nanoparticle-induced toxicity (Orecna et al, 2014). Thus, it is possible that the altered lysosomal activity may impair digestion and efflux of particles and lipids, which may be the mechanisms of A-DEP induced lipid droplet formation in macrophages.…”

Section: Discussionmentioning

confidence: 99%

Automobile diesel exhaust particles induce lipid droplet formation in macrophages in vitro

Cao¹,

Jantzen²,

Gouveia³

et al. 2015

Environmental Toxicology and Pharmacology

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Section: Discussionmentioning

confidence: 99%

Automobile diesel exhaust particles induce lipid droplet formation in macrophages in vitro

Cao¹,

Jantzen²,

Gouveia³

et al. 2015

Environmental Toxicology and Pharmacology

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“…This effect is partly attenuated upon mild stimulation of autophagy using low doses of bafilomycin A1, which causes extracellular release of nanomaterial from autophagic vesicles [57]. Exocytosis of autophagic vesicles has been proposed as a mechanism of release of nanomaterials.…”

Section: Blockage Of Autophagic Fluxmentioning

confidence: 99%

Differential autophagic responses to nano-sized materials

Popp

Segatori

2015

Current Opinion in Biotechnology

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Autophagy is a complex catabolic pathway that mediates degradation of excess or unwanted cytoplasmic components through the lysosome. Activated by environmental factors, such as nutrient depletion, and intracellular stimuli, such as proteotoxic stress, it provides a highly dynamic quality control mechanism to recycle cellular components, eliminate aberrant materials, and, ultimately, maintain cellular homeostasis. A growing body of evidence suggests that autophagy is also activated upon internalization of engineered nanomaterials, most likely as a protective response to what is perceived as foreign or toxic. This review describes the mechanisms of autophagy activation in response to naturally occurring and engineered nanomaterials. We provide a comprehensive analysis of the impact of nanomaterials on the lysosome-autophagy system, with particular emphasis on cellular markers associated with biocompatible and bioadverse outcomes of autophagy activation, such as clearance of toxic material and autophagy-associated cell death. Potential applications of the next-generation nanomaterials designed to interface with cellular clearance mechanisms with precisely tunable properties are also discussed.

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“…One method reported by several groups is to sonicate cCNT soot in deionized water before adding the resulting aqueous cCNT suspension to cell culture medium,[10–14] while others have reported an additional centrifugation step to purify the aqueous cCNT suspension (herewith called a centrifuged cCNT suspension) before adding this material to cell culture medium or blood. [15–18] Another important consideration for biomedical applications of CNTs is therefore a thorough physiochemical characterization of the exact CNT sample that is presented to living cells or intact organisms. [19–28] At a minimum, this involves some measure of CNT structures, amounts, dimensions, porosities, impurities, and in the case of cCNTs, a measure of surface acidity, defined as the acidic groups covalently attached to cCNT surfaces and potential acidic carbonaceous substances adsorbed to cCNT surfaces (i.e., oxidative debris).…”

Section: Introductionmentioning

confidence: 99%

Enriched surface acidity for surfactant-free suspensions of carboxylated carbon nanotubes purified by centrifugation

Braun

Draper

Pantano

2016

Analytical Chemistry Research

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It is well known that surfactant-suspended carbon nanotube (CNT) samples can be purified by centrifugation to decrease agglomerates and increase individually-dispersed CNTs. However, centrifugation is not always part of protocols to prepare CNT samples used in biomedical applications. Herein, using carboxylated multi-walled CNTs (cMWCNTs) suspended in water without a surfactant, we developed a Boehm titrimetric method for the analysis of centrifuged cMWCNT suspensions and used it to show that the surface acidity of oxidized carbon materials in aqueous cMWCNT suspensions was enriched by ~40% by a single low-speed centrifugation step. This significant difference in surface acidity between un-centrifuged and centrifuged cMWCNT suspensions has not been previously appreciated and is important because the degree of surface acidity is known to affect the interactions of cMWCNTs with biological systems.

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Toxicity of carboxylated carbon nanotubes in endothelial cells is attenuated by stimulation of the autophagic flux with the release of nanomaterial in autophagic vesicles

Cited by 63 publications

References 37 publications

Automobile diesel exhaust particles induce lipid droplet formation in macrophages in vitro

Automobile diesel exhaust particles induce lipid droplet formation in macrophages in vitro

Differential autophagic responses to nano-sized materials

Enriched surface acidity for surfactant-free suspensions of carboxylated carbon nanotubes purified by centrifugation

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