In vitro exposure to PM2.5 of olfactory Ensheathing cells and SH-SY5Y cells and possible association with neurodegenerative processes
Antonio Cristaldi, Gea Oliveri Conti, Rosalia Pellitteri, Valentina La Cognata, Chiara Copat, Eloise Pulvirenti, Alfina Grasso, Maria Fiore, Sebastiano Cavallaro, P. Dell’Albani, Margherita Ferrante
Abstract
PM 2.5 exposure represents a risk factor for the public health. PM 2.5 is able to cross the blood-alveolar and blood-brain barriers and reach the brain through three routes: nasal olfactory pathway , nose-brain pathway, blood-brain barrier pathway. We evaluated the effect of PM 2.5 to induce cytotoxicity and reduced viability on in vitro cultures of OECs (Olfactory Ensheathing Cells) and SH-SY5Y cells. PM 2.5 samples were collected in the metropolitan area of Catania, and the gravimetric determination of PM 2.5 , characterization of 10 trace elements and 16 polycyclic aromatic hydrocarbons (PAHs) were carried out for each sample. PM 2.5 extracts were exposed to cultures of OECs and SH-SY5Y cells for 24-48-72 h, and the cell viability assay (MTT) was evaluated. Assessment of mitochondrial and cytoskeleton damage, and the assessment of apoptotic process were performed in the samples that showed lower cell viability . We have found an annual average value of PM 2.5 = 16.9 μg/m 3 and a maximum value of PM 2.5 = 27.6 μg/m 3 during the winter season. PM 2.5 samples collected during the winter season also showed higher concentrations of PAHs and trace elements. The MTT assay showed a reduction in cell viability for both OECs (44%, 62%, 64%) and SH-SY5Y cells (16%, 17%, 28%) after 24-48-72 h of PM 2.5 exposure. Furthermore, samples with lower cell viability showed a decrease in mitochondrial membrane potential , increased cytotoxicity, and also impaired cellular integrity and induction of the apoptotic process after increased expression of vimentin and caspase-3 activity, respectively. These events are involved in neurodegenerative processes and could be triggered not only by the concentration and time of exposure to PM 2.5 , but also by the presence of trace elements and PAHs on the PM 2.5 substrate. The identification of more sensitive cell lines could be the key to understanding how exposure to PM 2.5 can contribute to the onset of neurodegenerative processes.