Genetic and Molecular Analysis of Micro- and Nanomaterials of Biomedical Interest

The synthesis of plastic polymers, started in the 19th century, helped industries to increase their production with cheap and malleable materials. Today, this massive usage brought to a consolidate environmental emergency: plastic residues are defined as the most spread pollutants in the world and they are found bioaccumulated in most organisms, humans included. The aim of my PhD thesis is to contribute to determine the impact of plastic residues on health and disease. I used Drosophila melanogaster as an in vivo model to test polystyrene nanoparticles as major representant of risk associated with oral exposure and murine macrophages as an in vitro model to test tire wears microparticles to assess respiratory exposure. I used the model organism Drosophila melanogaster to ascertain whether polystyrene nanoparticles (PSNPs) harm DNA, increase the incidence of cancer and worsen the course of genetic diseases associated with polycystic kidney and neurodevelopment. Orally administered fluorescent PSNPs were absorbed by intestinal cells and deposited in the fat body of wild-type flies. The weight of PSNPs-fed flies was significantly lower than negative controls, and they developed more slowly and showed reduced resilience to heat shock and starvation. When PSNPs were given to DNAlig4 mutants—which are known to be susceptible to dietary stresses—climbing performance was decreased. All of these findings imply that PSNPs have an effect on fly metabolism and development. Through qPCR analysis, I observed that the intestines of wild type larvae fed with PSNPs showed an upregulation of genes related to the cell damage response. PSNPs-fed heterozygous warts mutants, which are known to favor epithelial tumors even in humans, showed a larger number of aberrant masses than untreated flies, demonstrating the PSNPs carcinogenic potential. To assess the potential influence of PSNPs on further pathologies, I used Drosophila models of Polycystic Kidney Disease (PKD) and TANGO2 Deficiency Disorder (TDD) and detected aggravated diseased phenotypes in both cases. Specifically, PSNPs consumption increased cyst numbers in PKD flies and impaired climbing assay performance of TDD flies compared to wild-type controls. For the in vitro assessment on murine macrophages, I started with the chemical characterization of the materials using electron microscopy to confirm their composition. Then, the morphological assessment of the treated cells by transmission electron microscopy showed mitochondria and endoplasmic reticulum alterations. A qPCR was used for gene expression analysis and confirmed with western blotting. They showed the overexpression of cellular stress biomarkers. According to the findings, there was first evidence of an apoptotic process induction, although Bcl2 later reversed the trigger and treated cells did show some modest cellular anomalies.