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Exploring the Impact of Microplastics (Polyethylene terephthalate) in Lung cells
Summary
Laboratory experiments exposing A549 lung epithelial cells and alveolar macrophages to polyethylene terephthalate (PET) microplastics at environmentally relevant concentrations revealed inflammatory responses, impaired barrier integrity (measured by TEER), and oxidative stress comparable to known lung irritants. These findings suggest that PET fibers—the dominant form of airborne microplastic pollution—pose a credible respiratory health risk even at real-world exposure levels.
IntroductionMicroplastics (MPs) are plastic particles smaller than 5 millimetres that arise either from intentional production or the breakdown of larger plastics. They have been detected across diverse environments, including air, water, and soil, and more recently in human tissues such as the lungs. While their health impacts are not yet fully understood, evidence suggests that some particles can evade clearance mechanisms in the respiratory tract and trigger inflammatory responses, particularly in vulnerable individuals. Laboratory studies often use polystyrene beads as models, though airborne pollution is more commonly composed of fibres such as polypropylene (PP) and polyethylene terephthalate (PET). The detection of MPs in biological fluids like blood and urine further raises concern about their potential to move within the body and accumulate in organs.Based on this, we hypothesize that:MPs at environmentally relevant levels and sizes cause inflammation in lung cells associated with lung diseases.MethodsThis study investigated the effects of MPs on lung-related cell models and tissue. MPs in suspension were first characterized spectroscopically and dyed to distinguish them from environmental contamination. Their impact was assessed on A549 epithelial cells and alveolar macrophages (Daisy cells), focusing on cell viability (LDH and MTT assays), barrier integrity (TEER), and oxidative and cytokine responses. Silicon dioxide (SiO2) served as a positive control due to its known toxicity, while cellulose fibres (200–300 μm) were used as a negative control.ResultsExposure to PET MPs induced distinct oxidative and immune responses in A549 epithelial cells and Daisy macrophages. In A549 cells, low concentrations (0.02 mg/ml) reduced ROS, while higher doses (1 mg/ml) triggered oxidative stress; TEER reduction at 0.1 mg/ml indicated impaired barrier integrity. Cytokine analysis showed suppression of IL-15, TARC, and I-309. Daisy cells showed similar ROS trends, with increases at 1 mg/ml, and cytokine profiling revealed broad suppression (IL-12p40/p70, IL-13, IL-1β, IFN-γ, TNF-β) but strong induction of GRO-α, suggesting selective pro-inflammatory signalling.ConclusionPET MPs seem to exert dose-dependent effects on oxidative stress, barrier integrity, and cytokine signalling, with higher concentrations promoting cellular stress and immune disruption. Given their persistence and ubiquity, PET MPs pose risks to human health and ecosystems, underscoring the need for coordinated strategies to reduce plastic pollution.