Determinação de alterações fenotípicas subletais desencadeadas por microplásticos em dois modelos de hepatócitos humanos através de triagem cellular multiparamétrica de alto conteúdo

Author(s)

Mariana Rodrigues Da Silva

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2025-03-11

Examining board members

Marcelo Bispo de Jesus; Nicolas Carlos Hoch; Alexandre Bruni Cardoso

• Advisor: Marcelo Bispo de Jesus

Abstract

The uncontrolled accumulation of plastics in the environment constitutes a growing global problem. Microplastics (MPs) and nanoplastics (NPs), derived from the degradation of plastic waste and intentional production, are widely found in air, water, and various foods, with polystyrene (PS) being one of the most common types. It is estimated that humans ingest up to 5 g of these particles weekly, raising concerns due to the ability of MPs, especially those smaller than 150 µm, and NPs to cross the human intestinal barrier and accumulate in organs such as the liver, given its role in xenobiotic detoxification. Despite these concerns, there is still a lack of studies evaluating the hepatotoxic potential of MPs and NPs at environmentally relevant concentrations and levels reflective of human exposure. Given this scenario, this study aimed to investigate the hepatotoxicity of PS microplastics (PS-MPs) at concentrations ranging from 1 ng/L to 1 g/L, encompassing environmentally reported levels (1 ng/L and 1 µg/L), daily human exposure estimates (1 mg/L, considering the combined contribution of environmental concentrations, seafood ingestion, and consumption of food packaged in plastics), and extreme conditions (above 1 mg/L). Instead of using animal models, which have limitations in terms of time, prediction, cost, and ethical considerations, we chose to evaluate the toxic effects of PS-MPs in two human hepatocyte lineages, HepG2 and Huh7, employing assays based on cellular image analysis (High-Content Analysis). These approaches enabled the evaluation of changes in cellular profiles, including morphological and mechanistic alterations, through the use of various cellular markers, aiming for predictive results. The results demonstrated that, although PS-MPs did not trigger hepatotoxic effects at environmentally relevant concentrations (1 ng/L to 1 mg/L), these particles were associated with both hepatocyte lineages under these conditions. At elevated concentrations (0.5 g/L and 1 g/L), PS-MPs induced significant cellular changes, which varied between the lineages. For instance, a significant increase in acidic vesicles was observed in Huh7, while cellular disaggregation was noted in HepG2, both indicative of cellular stress. Additionally, a reduction in the number of dead cells was observed in both lineages, which may be related to the activation of cellular survival pathways. These findings suggest that, while environmental concentrations of PS-MPs do not cause immediate hepatotoxicity, exposure to higher concentrations can significantly impact hepatocyte models, revealing a hepatotoxic potential. Although elevated concentrations represent extreme scenarios, it is important to consider that human exposure to MPs is cumulative and occurs daily. Moreover, the continuous increase in the presence of these residues in the environment suggests that current environmental concentrations may rise over time, potentially approaching levels currently considered extreme. Our findings contribute to a deeper understanding of the hepatotoxic potential of PS-MPs in humans and highlight elements of Adverse Outcome Pathways (AOPs) associated with different PS-MP concentrations. These specific cellular alterations may eventually support the construction of AOPs for MPs in hepatic cells, offering valuable tools for assessing the risks posed by these particles to human health (AU)

• FAPESP's process: 22/07854-4 - Determination of microplastic-induced sublethal phenotypic changes in two human hepatocyte models using high-content analysis
• Grantee: Mariana Rodrigues da Silva
• Support Opportunities: Scholarships in Brazil - Master