Clarissa Marquardt

Screening of different metal oxide nanoparticles reveals selective toxicity and inflammatory potential of silica nanoparticles in lung epithelial cells and macrophages

Abstract In cell culture studies, foetal calf serum (FCS) comprising numerous different proteins is added, which might coat the surface of engineered nanomaterials (ENMs) and thus could profoundly alter their biological activities. In this study, a panel of industrially most relevant metal oxide nanoparticles (NPs) was screened for toxic effects in A549 lung epithelial cells and RAW264.7 macrophages in the presence and absence of FCS. In medium without FCS amorphous SiO2-NPs were the most cytotoxic NPs and induced a significant pro-inflammatory response in both cell types. An increased anti-oxidative response after exposure to SiO2-NPs was, however, only observed in RAW264.7 macrophages. Furthermore, pre-coating of SiO2-NPs with FCS proteins or simply bovine serum albumin abrogated responses in A549 lung epithelial cells. Thus, the protein corona bound to the surface of SiO2-NPs suppresses their biological effects, an issue which needs to be more carefully considered for in vitro–in vivo extrapolations.

In vitro toxicity of amorphous silica nanoparticles in human colon carcinoma cells

Abstract The use of nanostructured silica (SiO2) particles is no longer restricted to biomedical and (bio-) technological fields but rather finding applications in products of the food industry. Thus, our studies on the toxicological relevance of SiO2 nanoparticles focused on cytotoxic effects, the modulation of the cellular redox status and the impact on DNA integrity in human colon carcinoma cells (HT29). The results indicate that these SiO2 nanoparticles stimulate the proliferation of HT29 cells, depending on the incubation time and the particle size. The cytotoxicity of the investigated SiO2 nanoparticles was found to depend on the concentration, size and on the FCS content of the culture medium. Furthermore, SiO2 seem to interfere with glutathione biosynthesis. The results indicate further that effects of SiO2 NPs are not mediated by oxidative stress but by interference with the MAPK/ERK1/2 as well as the Nrf2/ARE signalling pathways. Additionally, investigations regarding DNA integrity revealed no substantial (oxidative) DNA damage.

Environmental impacts of nanomaterials: providing comprehensive information on exposure, transport and ecotoxicity - the project DaNa2.0

BackgroundAssessing the impact of new technologies or newly developed substances on our environment is a challenge, even more so if the applied test methods - both toxicological and analytical - are often found to be inadequate and need amendments or even new developments as it is in the case of nanotechnology. This is illustrated by numerous publications in the field of nano-ecotoxicology which although they have been investigating the impact of a number of nanomaterials on several organisms almost never allow for explicit statements on potential hazards of these nanomaterials. This fact not only hampers the knowledge communication to all non-scientists (e.g. consumers) but it also complicates the transfer of the obtained results for other scientists.ResultsRisk communication is an essential and thus integral part of risk management. For this purpose, the project DaNa2.0 (Data and knowledge on nanomaterials - processing of socially relevant scientific facts) provides processed and hence easy accessible information on the potential safety issues of nanomaterials, mainly via the project website http://www.nanoobjects.info. This will allow various stakeholder groups to get impartial information on potential effects of nanomaterials and help consumers to make informed decisions. DaNa2.0 is funded by the German Federal Ministry of Education and Research (BMBF) and supported by the Swiss government as well as by the European InterReg IVb programme. The DaNa2.0 team is an interdisciplinary group of scientists from different areas such as materials science, chemistry, biology and human and environmental toxicology. Extending the project team in DaNa2.0 with European experts allows for broadening of the existing knowledge portfolio by adding further cross-cutting topics and increasing our expertise, e.g. in the field of environmental exposure and fate.ConclusionsOn the project website http://www.nanoobjects.info, a unique link between nanomaterials in practical applications (e.g. environmental remediation) and their potential impacts is provided. The focus of this publication will be on all issues with environmental relevance, which are addressed in the ‘Knowledge Base Nanomaterials’ on the project website. These issues include environmental exposure and behaviour of nanomaterials and nano-ecotoxicology.

Autophagy induced by silica nanoparticles protects RAW264.7 macrophages from cell death

Although the technological and economic benefits of engineered nanomaterials are obvious, concerns have been raised about adverse effects if such material is inhaled, ingested, applied to the skin or even released into the environment. Here we studied the cytotoxic effects of the most abundant nanomaterial, silica nanoparticles (SiO2-NPs), in murine RAW264.7 macrophages. SiO2-NPs dose-dependently induce membrane leakage and cell death without obvious involvement of reactive oxygen species. Interestingly, at low concentrations SiO2-NPs trigger autophagy, evidenced by morphological and biochemical hallmarks such as autophagolysosomes or increased levels of LC3-II, which serves to protect cells from cytotoxicity. Hence SiO2-NPs initiate an adaptive stress response which dependent on dose serve to balance survival and death and ultimately dictates the cellular fate.

Latest research results on the effects of nanomaterials on humans and the environment: DaNa - Knowledge Base Nanomaterials

Nanotechnology is considered one of the key technologies of the 21st century. The success of this fascinating technology is based on its versatility. It will bring about fundamental changes of basic research as well as of many sectors of industry and also of daily life from electronics to the health care system. However, consumers often miss reliable and understandable information on nanomaterials and all aspects of this versatile technology. A huge body of data on the potential hazards of nanoobjects towards human and environmental health already exists, but is either not easily accessible for a broad audience or presented unprocessable for nonexperts. But risk communication is an essential and thus integral component of risk management. For that purpose, the DaNa-Project aims at filling this gap by collecting and evaluating scientific results in an interdisciplinary approach with scientists from different research areas, such as human and environmental toxicology, biology, physics, chemistry, and sociology. Research findings from the field of human and environmental nanotoxicology are being prepared and presented together with material properties and possible applications for interested laymen and stakeholders. For the evaluation of literature a Literature Criteria Checklist has been developed as well as a Standard Operation Procedure template (SOP) based on careful scientific practice.

The nucleotide excision repair protein XPC is essential for bulky DNA adducts to promote interleukin-6 expression via the activation of p38-SAPK

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants, and many are potent carcinogens. Benzo[a]pyrene (B[a]P), one of the best-studied PAHs, is metabolized ultimately to the genotoxin anti-B[a]P-7,8-dihydrodiol-9,10-epoxide (BPDE). BPDE triggers stress responses linked to gene expression, cell death and survival. So far, the underlying mechanisms that initiate these signal transduction cascades are unknown. Here we show that BPDE-induced DNA damage is recognized by DNA damage sensor proteins to induce activation of the stress-activated protein kinase (SAPK) p38. Surprisingly, the classical DNA damage response, which involves the kinases ATM and ATR, is not involved in p38-SAPK activation by BPDE. Moreover, the induction of p38-SAPK phosphorylation also occurs in the absence of DNA strand breaks. Instead, increased phosphorylation of p38-SAPK requires the nucleotide excision repair (NER) and DNA damage sensor proteins XPC and mHR23B. Interestingly, other genotoxins such as cisplatin (CDDP), hydrogen peroxide and ultraviolet radiation also enhance XPC-dependent p38-SAPK phosphorylation. In contrast, anti-benzo[c]phenanthrene-3,4-dihydrodiol-1,2-epoxide, the DNA adducts of which are not properly recognized by NER, does not trigger p38-SAPK activation. As a downstream consequence, expression and secretion of the pro-inflammatory cytokine interleukin-6 is induced by BPDE and CDDP in vitro and by CDDP in the murine lung, and depends on XPC. In conclusion, we describe a novel pathway in which DNA damage recognition by NER proteins specifically leads to activation of p38-SAPK to promote inflammatory gene expression.

Considerations about the implementation of a public knowledge base regarding nanotechnology

Nanotechnology ranks among the key technologies that will bring fundamental changes to basic research, many industry sectors and daily life. However, consumers often miss reliable and understandable information on nanomaterials. To create this transparency, the DaNa project collects and evaluates the latest scientific literature before publishing these on the website www.nanoobjects.info. Though all published articles are designed to meet the needs of different recipient groups, a certain knowledge about nanomaterials is presumed due to the nanomaterial-specific structuring of the website. This poses a barrier for interested laymen who usually have a particular nano-related application in mind. These application-oriented facts on nanomaterials already exist on the website but are scattered throughout the different articles. To overcome this, we first analyzed the state of the scattered information and then assessed requirements for a new tool displaying these facts: storage of extracted knowledge in a homogenous way, visualization options and integration of the new database into the existing content management system. We therefore extended our backend to capture knowledge on a semantically higher level in a database called DaNaVis. Based on this database we can increase the accessibility of DaNas project results by means of interactive visualization components.

The DaNa2.0 Knowledge Base Nanomaterials—An Important Measure Accompanying Nanomaterials Development

Nanotechnology is closely related to the tailored manufacturing of nanomaterials for a huge variety of applications. However, such applications with newly developed materials are also a reason for concern. The DaNa2.0 project provides information and support for these issues on the web in condensed and easy-to-understand wording. Thus, a key challenge in the field of advanced materials safety research is access to correct and reliable studies and validated results. For nanomaterials, there is currently a continuously increasing amount of publications on toxicological issues, but criteria to evaluate the quality of these studies are necessary to use them e.g., for regulatory purposes. DaNa2.0 discusses scientific results regarding 26 nanomaterials based on actual literature that has been selected after careful evaluation following a literature criteria checklist. This checklist is publicly available, along with a selection of standardized operating protocols (SOPs) established by different projects. The spectrum of information is rounded off by further articles concerning basics or crosscutting topics in nanosafety research. This article is intended to give an overview on DaNa2.0 activities to support reliable toxicity testing and science communication alike.