In Vitro Co-Exposure to CeO2 Nanomaterials from Diesel Engine Exhaust and Benzo(a)Pyrene Induces Additive DNA Damage in Sperm and Cumulus Cells but Not in Oocytes

Abstract

Benzo(a)pyrene (BaP) is a recognized reprotoxic compound and the most widely investigated polycyclic aromatic hydrocarbon in ambient air; it is widespread by the incomplete combustion of fossil fuels along with cerium dioxide nanomaterials (CeO2 NMs), which are used in nano-based diesel additives to decrease the emission of toxic compounds and to increase fuel economy. The toxicity of CeO2 NMs on reproductive organs and cells has also been shown. However, the effect of the combined interactions of BaP and CeO2 NMs on reproduction has not been investigated. Herein, human and rat gametes were exposed in vitro to combusted CeO2 NMs or BaP or CeO2 NMs and BaP in combination. CeO2 NMs were burned at 850 °C prior to mimicking their release after combustion in a diesel engine. We demonstrated significantly higher amounts of DNA damage after exposure to combusted CeO2 NMs (1 µg·L−1) or BaP (1.13 µmol·L−1) in all cell types considered compared to unexposed cells. Co-exposure to the CeO2 NMs-BaP mixture induced additive DNA damage in sperm and cumulus cells, whereas no additive effect was observed in rat oocytes. This result could be related to the structural protection of the oocyte by cumulus cells and to the oocyte’s efficient system to repair DNA damage compared to that of cumulus and sperm cells.

Nanostructured Ceria: Biomolecular Templates and (Bio)applications

“…Given the well-established use of ceria in car exhausts for the abatement of toxic gases, studies assessed the possibility of using ceria as diesel additives to reduce the emission of toxic compounds (such as benzo(a)pyrene) from the incomplete combustion of fossil fuels, and to increase fuel economy. As mentioned above, the potential release of the NPs in the environment required an accurate evaluation of the toxicity of nano-sized ceria, either alone or in combination with benzo(a)pyrene on reproductive cells revealing DNA damage [ 230 ]. This result was confirmed on sperm cells, where DNA damage [ 231 ] and oxidative stress due to ROS generation was found [ 232 ].…”

Combined effects of nanoparticles and other environmental contaminants on human health - an issue often overlooked

“…Still because of their small size, nanoparticles can translocate and reach the systemic circulation to be potentially distributed to other organs. This explains why some studies investigated the damages to the cardio-vascular system (Asweto et al, 2017;Feng et al, 2018Feng et al, , 2017 and to other organs (Cotena et al, 2021;Courter et al, 2007;Deville et al, 2016;Ku et al, 2017;Lai et al, 2020;Roje et al, 2019;Schirinzi et al, 2017;Teng et al, 2020;Xia et al, 2011). Among the different organs, the digestive system is quite well studied (Ahamed et al, 2020a(Ahamed et al, , 2019bCao et al, 2021Cao et al, , 2019Dussert et al, 2020;Shi et al, 2010;Zheng et al, 2012).…”

“…In Table 2, the category other/ various includes studies on the nervous system (Ku et al, 2017;Schirinzi et al, 2017), immune system (Deville et al, 2016), kidney cells (Xia et al, 2011), breast cells (Roje et al, 2019), on carcinogenesis (Courter et al, 2007), reproductive organs (Cotena et al, 2021), fetus (Teng et al, 2020) or deal with global effects, affecting several organs (Courter et al, 2007;Lai et al, 2020;Teng et al, 2020).…”

“…On the contrary, protective, antagonistic effects were observed in 23% of the studies. It should also be mentioned that sometimes no effect was observed (Guo et al, 2021;He et al, 2020) or opposite effects could be shown depending on the nature of the mixture, the biological model or the biological endpoint considered (Cotena et al, 2021;Courter et al, 2007;Lee et al, 2019).…”

“…Cotena et al showed that co-exposure to CeO2 nanoparticles and benzo[a]pyrene induced additive DNA damage in sperm and cumulus cells compared to those generated by the individual pollutants, whereas no additive toxic effect was observed in rat oocytes. They attributed this result to the structural protection of the oocyte by cumulus cells and to the oocyte's efficient system to repair DNA damage compared to that of cumulus and sperm cells (Cotena et al, 2021).…”