Autophagy is involved in nanoalumina-induced cerebrovascular toxicity

doi:10.1016/j.nano.2012.05.017

Nanomedicine: Nanotechnology, Biology and Medicine

Volume 9, Issue 2, February 2013, Pages 212-221

https://doi.org/10.1016/j.nano.2012.05.017 Get rights and content

Abstract

The current study focused on blood–brain barrier disruption and neurovascular damage induced by engineered nanomaterials. Exposure to nanoalumina, but not to nanocarbon, induced a dose-dependent mitochondrial potential collapse, increased autophagy of brain endothelial cells, and decreased expression of the tight-junction proteins occludin and claudin-5. Inhibition of autophagy by pretreatment with Wortmannin attenuated the effects of nanoalumina on decreased claudin-5 expression; however, it did not affect the disruption of occludin. These findings were confirmed in mice by administration of nanoalumina into the cerebral circulation. Systemic treatment with nanoalumina elevated autophagy-related genes and autophagic activity in the brain, decreased tight-junction protein expression, and elevated blood–brain barrier permeability. Finally, exposure to nanoalumina, but not to nanocarbon, increased brain infarct volume in mice subjected to a focal ischemic stroke model. Overall, our study reveals that autophagy constitutes an important mechanism involved in nanoalumina-induced neurovascular toxicity in the central nervous system.

From the Clinical Editor

In this paper, the effects of nanoalumina on the permeability of the blood-brain barrier is reported, suggesting that autophagy is an important mechanism in nanoalumina-induced neurovascular toxicity.

Graphical abstract

Exposure to nanoalumina induces a dose-dependent mitochondrial potential collapse, increases autophagy of brain endothelial cells, and decreases expression of tight-junction proteins. These changes contribute to elevated blood–brain barrier permeability and increased brain infarct volume in mice subjected to a focal ischemic stroke model. Overall, these results indicate that autophagy constitutes an important mechanism involved in nanoalumina-induced neurovascular toxicity in the central nervous system.

Section snippets

Cell culture and treatment factors

Well-characterized human cerebral microvascular endothelial cells (HCMECs/D3 cells) were cultured as described earlier.⁶ Nanoalumina (8- to 12-nm particle size; Alfa Aesar, Ward Hill, Massachusetts) stock solution was prepared in distilled water, which was then diluted in culture medium (for cell culture studies) or phosphate buffered saline (for animal injections), and sonicated for 15 minutes before administration to avoid generation of aggregates. The particle size distribution was measured

Nanoalumina enters HCMECs and crosses the BBB to accumulate in the brain

ARS-nanoalumina (1 μg/mL, stained red) was detected in HCMECs following a 2-hour treatment (Figure 1, A, middle panel, arrows). After a 12-hour exposure, ARS-nanoalumina was visible as aggregates in proximity to clustered mitochondria as assessed by staining with MitoTracker Green (Figure 1, A, right panel, arrows).

To determine the fate of nanoalumina in the brain, ARS-nanoalumina was injected at the dose of 1.25 mg/kg into the mouse cerebral circulation via the carotid artery. The brain

Discussion

Unique characteristics of ENMs have raised concerns about their adverse effects on the environment and human health.3, 4 ENMs can penetrate cell membranes and interfere with cellular organelles, causing potentially unexpected and/or unintentionally adverse effects. The present study has focused on the cerebrovascular toxicity of ENMs at the BBB level. In addition, because autophagy has been recognized as a general cell response to stress,¹⁶ we evaluated whether nanoalumina can act as an

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: Support: MH63022, MH072567, DA027569, ES07380, DA027569, and postdoctoral fellowship for L. Chen from the American Heart Association.

¹: Current address: Department of Neuroscience, Mount Sinai School of Medicine, New York, New York, USA.

²: Current address: Department of Biochemistry and Molecular Biology, Miller School of Medicine, University of Miami, Miami, Florida, USA.

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Research ArticleAutophagy is involved in nanoalumina-induced cerebrovascular toxicity

Abstract

From the Clinical Editor

Graphical abstract

Section snippets

Cell culture and treatment factors

Nanoalumina enters HCMECs and crosses the BBB to accumulate in the brain

Discussion

Nanomed Nanotechnol Biol Med

Neurotoxicology

Toxicol Lett

Neuron

Nanomed Nanotechnol Biol Med

Methods Enzymol

FEBS Lett

Cell

Cell

Trends Neurosci

Research Article
Autophagy is involved in nanoalumina-induced cerebrovascular toxicity