Circular RNAs in Toxicology

Circular RNAs (circRNAs) are a type of closed, long, non-coding RNAs, which have attracted significant attention in recent years. CircRNAs exhibit unique functions and are characterized by stable expression in various tissues across different species. Because the identification of circRNA in plant viroids in 1976, numerous studies have been conducted to elucidate its generation as well as expression under normal and disease conditions. The rapid development of research focused on the roles of circRNAs as biomarkers in diseases such as cancers has led to increased interests in evaluating the effects of toxicants on the human genetics from a toxicological perspective. Notably, increasing amounts of chemicals are generated in the environment; however, their toxic features and interactions with the human body, particularly from the epigenetic viewpoint, remain largely unknown. Considering the unique features of circRNAs as potential prognostic biomarkers as well as their roles in evaluating health risks following exposure to toxicants, the aim of this review was to assess the latest progress in the research concerning circRNA, to address the role of the circRNA-miRNA-mRNA axis in diseases and processes occurring after exposure to toxic compounds. Another goal was to identify the gaps in understanding the interactions between toxic compounds and circRNAs as potential biomarkers. The review presents general information about circRNA (ie, biogenesis and functions) and provides insights into newly discovered exosome-contained circRNA. The roles of circRNAs as potential biomarkers are also explored. A comprehensive review of the available literature on the role of circRNA in toxicological research (ie, chemical carcinogenesis, respiratory toxicology, neurotoxicology, and other unclassified toxicological categories) is included.

Quantification of Cigarette Smoke Particle DepositionIn VitroUsing a Triplicate Quartz Crystal Microbalance Exposure Chamber

There are a variety of smoke exposure systems available to the tobacco industry and respiratory toxicology research groups, each with their own way of diluting/delivering smoke to cell cultures. Thus a simple technique to measure dosein vitroneeds to be utilised. Dosimetry—assessment of dose—is a key element in linking the biological effects of smoke generated by various exposure systems. Microbalance technology is presented as a dosimetry tool and a way of measuring whole smoke dose. Described here is a new tool to quantify diluted smoke particulate depositionin vitro. The triplicate quartz crystal microbalance (QCM) chamber measured real-time deposition of smoke at a range of dilutions 1 : 5–1 : 400 (smoke : air). Mass was read in triplicate by 3 identical QCMs installed into onein vitroexposure chamber, each in the location in which a cell culture would be exposed to smoke at the air-liquid interface. This resulted in quantification of deposited particulate matter in the range 0.21–28.00 μg/cm2. Results demonstrated that the QCM could discriminate mass between dilutions and was able to give information of regional deposition where cell cultures would usually be exposed within the chamber. Our aim is to use the QCM to support the preclinical (in vitro) evaluation of tobacco products.