Model/experimental organisms to estimate oxidative stress and health effects induced by in vivo exposure to different PM components

In recent years, numerous acellular and cellular assays have been developed to estimate oxidative stress and health effects induced by exposure to particulate matter (PM) with different physical and chemical properties. Acellular assays evaluate the oxidative potential of PM, they are rapid and low cost but their ability to estimate PM health effects has not yet been fully demonstrated. Cellular assays evaluate different biomarkers, but they are time-consuming and expensive and do not consider the complexity of the biological response of a living organism. To overcome these critical issues, recent studies suggest the evaluation of in vivo biological responses of model/experimental organisms directly exposed to atmospheric aerosol (de Santana et al., 2018; Vaccarella et al., 2023) since they consider the complexity of a complete living organism. The aim of this study is to evaluate the efficiency of insects (e.g., Aedes albopictus and Drosophila melanogaster) as indicators of the ability of PM to induce oxidative stress and other health effects. For this purpose, individuals of Ae. albopictus were exposed in laboratory conditions (ex situ) to increasing concentrations (10-500 mg L-1) of brake dust (< 50 µm), which was produced by mechanical abrasion of car brake pads. For each pool of individuals, bioaccumulation of 40 elements was evaluated by ICP-MS analysis, and the generation of oxidative stress was assessed by spectrophotometric determination of the content of superoxide anion (·O2-), an efficient oxidative stress biomarker. The results obtained show a strong effect of the brake dust on the development time of the individuals. From a concentration of 100 mg L-1 and above, no individual succeeded in reaching the pupa stage, and in all cases, dust exposure resulted in a lengthening of both larval development time and flicker time. The results show a dose-dependent increase in mortality and bioaccumulation of Cu, Zn, and other transition metals in brake dust, well known to trigger and catalyze oxidative stress reactions (Ficociello et al., 2020). Principal component analysis (PCA) was performed to assess the relationships between the elements bioaccumulated and health effects on the individuals exposed to different concentrations of brake dust and confirm a strong correlation between mortality and increasing concentrations of Cu (Fig. 1). Ae. albopictus was found to be an efficient organism to evaluate the effects induced by in vivo exposure to PM. Moreover, Ae. albopictus and D. melanogaster can be exposed in situ directly to atmospheric aerosol under real environmental conditions. In this regard, exposure boxes were designed to control the temperature and relative humidity inside the box by allowing the passage of the aerosol from outside to inside the box. This innovative method allowed the exposure of pools of D. melanogaster individuals to different PM urban (i.e., biomass domestic heating, vehicular traffic) and industrial (i.e. foundry) emission sources under real environmental conditions PM to which individuals were exposed was chemically characterized for oxidative potential (OPDCFH, OPDTT and OPAA), OC, EC, ions, macro- and trace elements, levoglucosan, PAHs, and trace elements. Elements’ bioaccumulation, oxidative stress, and effects on development and mortality of the exposed individuals were evaluated. Oxidative stress was assessed by both targeted analysis (i.e., spectrophotometric determination of ·O2-) and nontargeted metabolomic analysis by NMR. An evaluation of correlations between the chemical composition of PM, its oxidative potential, oxidative stress, metabolites production and health effects measured on the organisms exposed in vivo is currently underway.