Plastic is now present almost everywhere. Over time, however, it breaks down into increasingly smaller fragments – microplastics and, eventually, nanoplastics, which are thousands of times smaller than the thickness of a human hair. Scientists have already detected them not only in water, food, and air, but also in human blood. However, much remains unknown about how they affect our health.
A new study by researchers from Wroclaw Medical University, published in Ecotoxicology and Environmental Safety, shows that after just one hour of exposure to nanoplastics, mitochondria – the cell’s “power plants” – become impaired, and stress-response mechanisms are activated in immune cells. Although the findings do not yet demonstrate that nanoplastics cause specific diseases, they provide important insights into the biological mechanisms through which these particles may affect the human body.
Smaller particles, bigger questions
Nanoplastics are formed as larger plastic materials degrade. Because of their microscopic size, they can enter the body through food, drinking water, or inhaled air, then reach the bloodstream and various organs.
Although their presence has recently been confirmed in multiple human tissues, scientists still do not know the long-term health consequences of chronic exposure.
We are learning more and more about how nanoplastics interact with human cells, but we are still unable to assess the actual health risks associated with everyday exposure. Answering this question will require long-term studies combining laboratory research with population-based investigations, – says Prof. Marek Jutel from the Department of Clinical Immunology at Wroclaw Medical University, a co-author of the study.
Looking inside the cell
The researchers investigated the effects of polystyrene nanoplastics on human peripheral blood mononuclear cells (PBMCs), a group of immune cells that includes T lymphocytes, B lymphocytes, and monocytes, all of which play key roles in the body’s immune response.
The study combined several advanced techniques that allowed the scientists to follow the entire process of nanoplastic exposure – from cellular uptake, through structural and metabolic changes, to the analysis of gene activity in thousands of individual cells.
The experiments confirmed that nanoplastics readily enter immune cells, where they remain within the cytoplasm.
Mitochondria under pressure
One of the study’s most important findings was that mitochondrial function became impaired after only one hour of exposure. Mitochondria are responsible not only for producing the energy required for normal cellular function but also for regulating cell activity, survival, and immune responses.
The researchers observed reduced mitochondrial respiration, decreased ATP production, and diminished cell responsiveness to increased energy demands. At the same time, the cells became smaller, more compact, and displayed features consistent with severe cellular stress.
After only one hour of exposure, we observed mitochondrial dysfunction together with activation of cellular stress-response pathways. This shows that even short-term exposure to nanoplastics can affect fundamental biological processes in immune cells, – explains Prof. Marek Jutel.
Cells switch into survival mode
Gene expression analysis revealed another intriguing finding. The researchers identified a population of cells that appeared exclusively after exposure to nanoplastics. They termed these stress cells.
These cells strongly activated the production of proteins that protect against cellular damage and repair misfolded proteins. At the same time, genes involved in normal mitochondrial function became less active.
According to the authors, this suggests that some immune cells temporarily abandon their normal functions and instead activate survival mechanisms to cope with adverse conditions.
The researchers also investigated whether nanoplastics influence basophils, immune cells involved in allergic reactions. Unlike the mitochondrial changes, however, no increase in basophil activation was observed.
This indicates that nanoplastics do not stimulate all components of the immune system equally. Instead, their primary effect appears to involve disruption of cellular metabolism and activation of stress-response pathways.
Our findings demonstrate that nanoplastics can enter immune cells and interfere with their metabolism. This does not yet establish a link with specific diseases, but it identifies a biological mechanism that deserves further investigation, – says Prof. Magdalena Zemelka-Wiącek from the Department of Clinical Immunology at Wroclaw Medical University.
Human and environmental health are interconnected
The authors emphasize that their work aligns with the One Health concept, which recognizes that the health of humans, animals, and the environment is closely interconnected.
Plastic pollution is no longer solely an environmental issue. Increasing evidence suggests that its effects can also be observed at the cellular level.
Plastic pollution is no longer only an environmental concern. Our study shows that its effects can also be detected at the cellular level, highlighting the need for research that integrates medicine, toxicology, and environmental sciences, – adds Prof. Magdalena Zemelka-Wiącek.
Although many questions remain unanswered, the study provides one of the most detailed descriptions to date of how nanoplastics affect human immune cells. It represents another important step toward understanding the biological consequences of plastic pollution and offers further evidence supporting efforts to reduce plastic contamination in the environment.
This article is based on the publication:
Authors: Bilska AG, Chaszczewska-Markowska M, Gajdanowicz P, Kosowska A, Pietrzak M, Shamji MH, Jutel M, Zemelka-Wiącek M.