In vitro effects of polystyrene microplastics exposure on adipose tissue dysfunction

Microplastics (MPs) are ubiquitous plastic particles with significant human health concerns due to their widespread distribution in the environment. The present study aims to evaluate the impact of exposure to polystyrene (PS) MPs (5 μm) on adipose tissue functionality using a well-established in vitro model of murine 3T3-L1 adipocytes, mimicking two distinct environmental exposure scenarios: fully differentiated mature adipocytes and preadipocytes undergoing the differentiation process. In fully differentiated adipocytes, PS MPs exposure did not produce significant alterations in key markers of adipogenesis (PPARγ and FASN), endoplasmic reticulum (ER) stress (p-eIF2α and GRP78), or inflammation (IL-6 and MCP-1). Interestingly, PS MPs exposure during adipocyte differentiation process significantly promoted adipocyte hypertrophy, as evidenced by the upregulation of adipogenic markers. Additionally, MPs induced reactive oxygen species and main key markers of the ER stress response and apoptosis. Finally, our results demonstrated that PS MPs exposure triggered an inflammatory response. In conclusion these findings underscore the multifaceted impact of PS MPs on adipose tissue during differentiation, demonstrating their ability to perturb oxidative balance and ER homeostasis, and to induce inflammatory signaling. Finally, our results emphasize the importance of the stage-specific responses in assessing the impact of environmental contaminants on adipose tissue function.