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Distinct pro-inflammatory responses to pristine and microbially contaminated PET nanoplastics in a human alveolar cell co-culture
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Scientists tested how tiny plastic particles from recycled PET bottles (the plastic used in water bottles) affect lung cells, and found that plastic contaminated with bacteria triggered a much stronger inflammatory response than clean, uncontaminated plastic particles. This suggests that germs riding along on plastic waste—not necessarily the plastic itself—may be a bigger driver of lung irritation, which is especially relevant for workers in recycling and waste facilities who breathe in plastic dust regularly. The plastic didn't kill the cells in either case, but the findings suggest that future safety testing on microplastics
Background: The small size of nanoplastics (NPs; <1 µm in diameter) facilitates airborne transport, inhalation, and deposition in the lungs, raising significant concerns about potential effects on human health. In occupational settings, such as waste management and recycling facilities, exposure to NPs carrying microbial contaminants may pose an additional health risk to workers. In the present study, we investigated pulmonary cytotoxicity and pro-inflammatory responses after exposure to polyethylene terephthalate nanoplastics (PET-NPs) with or without microbial contaminants. Methods: PET-NPs were synthesized from a post-consumer juice bottle (PET b001) and commodity PET pellets (PET c000). The presence of microbial contaminants was assessed via receptor activation in HEK293 Toll-like receptor (TLR) reporter cells expressing TLR2 or TLR4. Co-cultures of human alveolar epithelial cells (A549) and monocyte-derived macrophages (dTHP-1) were exposed to PET-NPs (0, 10 or 100 μg/mL) that tested either negative or positive for TLR2 and TLR4 activation. After 24 h, cell viability was measured, and cytokine responses were quantified at both mRNA and protein levels. Results: PET b001 activated TLR2 and TLR4, indicating the presence of biologically active microbial components, whereas PET c000 showed no activation. In A549/dTHP-1 co-cultures, PET b001 (10 and 100 μg/mL) significantly increased IL-1B, IL-6, IL-8, and TNF mRNA levels and IL-6 and IL-8 protein secretion. In comparison, PET c000 selectively increased IL-8 mRNA levels and protein secretion, and only at the highest tested concentration (100 μg/mL). No changes in cell viability were observed for either particle type. Conclusion: We found that the pro-inflammatory responses to PET-NPs are largely mediated by associated microbial components rather than the polymer itself, highlighting the importance of accounting for environmental context when evaluating their health risks. No evidence of cytotoxicity was observed, as cell viability remained unchanged. Our results further emphasize the need to assess microbial contamination prior to toxicity testing and point to potential occupational health risks in plastic waste and recycling environments.
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Harmful effects of true-to-life nanoplastics derived from PET water bottles in human alveolar macrophages.
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Researchers tested nanoplastics derived from actual PET water bottles on mouse lung immune cells, focusing specifically on cells that had internalized the particles. Even though the nanoplastics were taken up by 100% of cells at the highest dose, they did not cause outright cell death. However, they did trigger significant increases in reactive oxygen species and shifted the immune cells toward a pro-inflammatory state, suggesting that inhaled nanoplastics from everyday plastic products could promote chronic lung inflammation.
Respirable polyethylene terephthalate microplastics modulate airway inflammation and immune responses in murine allergen co-exposure models
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Scientists exposed mice to tiny plastic particles from PET (a common plastic in bottles and polyester clothing) and found the particles stuck around in the lungs for two weeks and triggered inflammation, especially when combined with allergens like ragweed pollen. This suggests breathing in these ultra-small plastic fragments could worsen allergic reactions or immune responses, though this was tested in mice at controlled doses, so more research is needed before we know exactly what this means for people breathing in everyday microplastics.
Microplastics and nanoplastics as possible carriers and/or indirect modulators of microbial metagenomes: Any effect on human health?
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This review looks at how tiny plastic particles in our environment can carry bacteria, including harmful ones, and possibly disrupt the healthy microbes in our gut and lungs. Early animal studies hint this could contribute to inflammation and disease, but scientists stress there's no solid proof yet that this happens in humans, more research is needed.
Insights into PET-Microplastics effect on pathogenic bacteria
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Researchers exposed four common disease-causing bacteria to PET microplastics and found that the bacteria responded differently depending on the species and plastic concentration, with some growing faster in the presence of plastics. Notably, bacteria exposed to higher concentrations of PET microplastics developed increased resistance to multiple antibiotics, raising concerns about how environmental plastic pollution could contribute to the growing antibiotic resistance problem.
Microplastics exposed by respiratory tract and exacerbation of community-acquired pneumonia: The potential influences of respiratory microbiota and inflammatory factors
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Researchers found that microplastics were present in the lungs of pneumonia patients, and that patients with severe pneumonia had higher levels of microplastics in their airways than those with milder cases. The microplastics appeared to worsen lung infections by disrupting the balance of airway bacteria and increasing inflammation. This study provides early evidence that inhaled microplastics may make respiratory infections more dangerous in humans.
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