| dc.description.abstract | Micro- and nanoplastics (MNPs) are of growing concern due to their widespread presence and persistence in the environment, including occupational settings. These particles could potentially cause harmful health effects in humans who are exposed to through inhalation, ingestion, or dermal contact. Plastics may also contain toxic additives and have been shown to adsorb environmental contaminants through hydrophobic interactions, possibly enabling MNPs to act as vectors for pathogens when entering the human body. The focus of this master's thesis has been to investigate the impact of microplastics (MPs) and endotoxin contaminants on two cell types that are part of the human lung, namely alveolar type II cells (A549) and neutrophil-like cells (dHL-60). Cytotoxic and pro-inflammatory responses were assessed after exposing these cells to MPs in the form of polyethylene terephthalate (PET) and PET contaminated with lipopolysaccharide (LPS), an endotoxin from the outer membrane of Escherichia coli 055:B5. In detail, this included investigating toll-like receptor (TLR) activation, specifically TLR2 and TLR4, pro-inflammatory cytokines (IL-6, IL-8, TNFα, and IL-1β) by gene expression and protein secretion, and changes in cell viability. The findings indicate increased cell viability after exposing A549 and dHL-60 cells to either PET-MPs or LPS-contaminated PET-MPs. The effect was concentration-dependent, with the two cell lines responding differently. In dHL-60 cells, LPS-contaminated PET-MPs induced oxidative burst and expression and release of IL-6 and IL-8 compared to PET-MP, although not beyond what was observed after exposure to LPS alone. In A549 cells, LPS-contaminated PET-MPs did not affect the expression and release of pro-inflammatory cytokines. The PETMPs used in this study exhibited pro-inflammatory effects, likely caused by the presence of microbial contaminants. Like the LPS-contaminated PET-MPs, they also were found to activate only TLR2, while LPS-contaminated PET-MP activate TLR2 and TLR4. The findings support the hypothesis that contaminated PET-MPs can affect cell viability and cellular immune responses and underline the complex interactions between MPs and biological systems. Further research is needed to fully understand the effects of MPs on human health. | nob |