Di Cristo, L; Mc Carthy, S; Paton, K; Movia, D; Prina-Mello, A (2018) Interplay between oxidative stress and endoplasmic reticulum stress mediated- autophagy in unfunctionalised few-layer graphene-exposed macrophages. 2D Materials, 5 (4). 045033 ISSN 2053-1583

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Abstract

The remarkable physico-chemical properties of graphene make it an ideal material for many applications, including the biomedical field. Unfunctionalised few-layer graphene (FLG) refers to graphene materials and formulations which have low or no defects in the graphene sheet structure, thus enhancing their physico-chemical properties. However, the use of FLG and its derivatives is not without risk to human health. It is largely accepted that the generation of reactive oxygen species and the consecutive inflammatory response, is at the basis of its toxicity; nonetheless the signaling pathways triggered by FLG still need to be explored in detail. The present study was aimed at providing some elucidations on the specific molecular signaling induced by low doses of a well characterize FLG material in macrophages. Exposure to low doses of FLG resulted in no significant decrease of macrophage viability. Nevertheless, it elicited a marked oxidative stress. The latter triggered significant inflammatory responses, increasing Tumor Necrosis Factor-alpha (TNF-¿) and Interleukin-6 (IL-6) secretion as well as Nitric Oxide (NO) production, leading to autophagy via endoplasmic reticulum (ER) stress. Indeed, exposure to FLG in the presence of 4-phenylbutyrate (4-PBA) and N-acetyl-L-cysteine (NAC), inhibitors of ER stress and oxidative stress, respectively, decreased ER stress, autophagy, oxidative stress and inflammation. Interestingly, graphene exposure did not induce Interleukin-1Beta (IL-1ß) and Interleukin-18 (IL-18) secretion, which are indicators of inflammasome activation. Pre-treatment with 3-Methyladenine (3-MA), an autophagy inhibitor, actually suppressed the autophagy activation triggered by graphene exposure, but leaded to inflammasome activation. Our work describes the molecular signaling by which macrophages respond to low doses of FLG, highlighting for the first time for this type graphene an interplay between oxidative stress and ER stress-mediated autophagy. It also suggests that such a pathway could protect the cells from exaggerated inflammation. Therefore, this study underline the importance of having a clear overview on the mechanism behind the interaction between FLG and cells, especially when graphene is used for the development of novel biomedical materials.

Item Type:	Article
Keywords:	unfunctionalised few-layer graphene, fingerprint characterization, oxidative stress, endoplasmic reticulum stress, autophagy, inflammasome
Subjects:	Advanced Materials > Functional Materials
Divisions:	Chemical, Medical & Environmental Science
Identification number/DOI:	10.1088/2053-1583/aadf45
Last Modified:	23 Oct 2018 14:47
URI:	http://eprintspublications.npl.co.uk/id/eprint/8115

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