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Impact of Engineered Nanomaterials in Genomics and Epigenomics

Saura C. Sahu

FORMER (retired) emplyee of the Food and Dug Administaration Columbia, MD, USA

Nanotechnology: A Technological Advancement of the Twenty-First Century

Nanotechnology is a new technological development of the twenty-first century. The US National Nanotechnology Initiative (NNI) defines nanotechnology as "the understanding and control of matter at dimensions between approximately 1 and 100 nm, where unique phenomena enable novel applications" (NNI 2014; NSTC 2011). Nanotechnology is a new and developing technology. The ratio of the surface area to volume of a nanoparticle is high compared with its larger counterpart (Roduner 2006). This property makes them more reactive compared with the larger particles. Engineered nanomaterials are used in a wide range of consumer products (Shen et al. 2013), such as cosmetics, drugs, medical devices, paints, nanofabric clothes, and electronics because of their superior physiochemical properties. They demonstrate better magnetic, electrical, optical, and thermal properties compared with their larger counterparts. Therefore, they have found useful applications in different areas of development, such as agriculture, energy, environment, medicine, biotechnology, and material science. They have shown great potential for impacting human life because of their beneficial properties.

Genomics and Epigenomics

The National Institute of Health (NIH) defines genomics as "the study of all of a person's genes (the genome), including interactions of those genes with each other and with the person's environment". The National Cancer Institute (NCI) defines genomics as an interdisciplinary field of biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is defined as a complete set of DNA, including all of its genes in an organism. The genome contains all the information needed for an organism to develop and grow. The global analysis of gene expression profiles provides a comprehensive view of toxicity and disease.

In genomic mechanisms of toxicity and disease, the genomic DNA sequence is altered by the chemical exposure. Such modified genomic DNA sequences are not cell and tissue specific. However, in some cases, toxicity and diseases are caused by DNA modifications due to chemical exposure, but in the absence of any direct alteration in genomic DNA sequence. Such DNA modifications without direct alterations in genomic DNA sequences are known as epigenomics, where DNA methylation regulates gene expression without direct alteration in the DNA sequence. In DNA methylation, gene expression occurs at the cytosine dinucleotide when a methyl group is added at position-5 producing methylcytosine (de Gannes et al. 2020). Unlike genomic changes, the epigenetic changes are cell and tissue specific. The epigenetic changes may be heritable and nonheritable. DNA methylation is associated with several human diseases including cancer.

The epigenome is defined as heritable biological information contained outside the DNA sequence (Dolinoy and Jirtle 2008). It consists of DNA methylation, histone modifications, and microRNAs. Noncoding RNAs (ncRNAs) regulate gene expression at the transcriptional or posttranslational levels without changing the genomic DNA sequence.

Beneficial Impacts of Engineered Nanomaterials on Human Life

Engineered nanomaterials demonstrate a huge potential to transform human life for the better. Their use in consumer products is increasing rapidly. They are used in our food, cosmetics, medicine, and agriculture (Sahu and Hayes 2017). They are used in our water filters to remove microorganisms, such as bacteria from drinking water. They are used in water treatment systems. They are used to make our fabrics fire resistant and to prepare plastic bottles for daily use. They are used in cosmetics, sunscreens, pharmaceuticals, medicine, and medical devices. They are used for drug delivery in chemotherapy and as nanosensors for patients. They are used in computer circuits and for fuel efficiency in vehicles. Engineered nanomaterials are used in vehicles and sports equipment to make them lighter, stronger, and chemical resistant. They are used in solar plastics to collect solar energy. They are used to clean up chemical spills and airborne pollutants.

Potential Adverse Health Effects of Engineered Nanomaterials

Humans are exposed to engineered nanomaterials every day. Therefore, the health effects of these nanomaterials are of public concern. In spite of the various beneficial impacts of engineered nanomaterials on human life, our knowledge of engineered nanomaterials is not complete. We must keep in mind that nanoscience is a developing new science. Many things remain unknown. We do not know much about long-term effects engineered nanomaterials. We do not know much about their safety. Many questions about their potential effects on our health, planet, and ecosystems come to our mind. At the moment, they are unregulated. There are no recognized standards for producing and handling them. Are they safe? Are they double-edged swords? Such concerns will continue to exist in our minds until more is known about them. At the moment, it is up to us to trust nanoscience or avoid it as much as possible.

The molecular mechanisms of gene-environment interactions have attracted widespread interest in recent years. These effects may be of genomic and/or epigenomic in nature, highlighting potential molecular targets following the exposure of engineered nanomaterials.

Thai et al. (2016) published the first report on genomic effects of titanium dioxide nanomaterials in an in vitro study using human liver HepG2 cells. This study linked some of the in vitro canonical pathways to in vivo adverse outcomes: NRF2-mediated response pathways to oxidative stress, acute phase response to inflammation, cholesterol biosynthesis to steroid hormones alteration, fatty acid metabolism changes to lipid homeostasis alteration, G2/M cell checkpoint regulation to apoptosis, and hepatic fibrosis/stellate cell activation to liver fibrosis.

Bicho et al. (2020) in a multigenerational study demonstrated epigenetic effects of copper oxide nanomaterials in environmental species Enchytraeus crypticus. Using gene expression analyses, they showed changes in the epigenetic gene targets, depending on the generation and form of copper. Also, they showed its transgenerational effects in postexposure generations. They observed nanoparticle-specific effects indicating differences between organisms exposed to different forms of copper.

Lu et al. (2016) and Sierra et al. (2016) reported the effect of nanomaterial exposure on the mammalian epigenome.

Conclusions

Currently, engineered nanomaterials appear to be double-edged swords. They impact our lives both ways, good and bad. We benefit from them in many ways, but at the same time we are concerned about their adverse health effects. Public concern about their safety will continue until we understand them completely. At the moment, it is up to us to trust nanoscience or avoid it as much as possible.

With regard to the need for a book on the impact of engineered nanomaterials in genomics and epigenomics, the rate of publications during the past few years has demonstrated that the impact of engineered nanomaterials in genomics and epigenomics has attracted widespread interest and, therefore, there is a need for new means to report the updated current status of this developing area of research. As the editor of this monograph Impact of Engineered Nanomaterials in Genomics and Epigenomics, it gives me great pride, pleasure, and honor to introduce this unique book that encompasses many aspects of genomic and epigenomic research never published together before.

References

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