Microplastics with a "crown" of whey proteins disrupt the work of neurons and microglia

Scientists from DGIST (South Korea) have shown that when microplastics enter biological environments (for example, blood), they quickly become “overgrown” with proteins, forming the so-called protein corona. In the experiment, such “crowned” particles caused significant reorganization of the proteome in neurons and microglia: protein synthesis, RNA processing, lipid metabolism, and transport between the nucleus and cytoplasm suffered; inflammatory signals were simultaneously activated. Conclusion: microplastics associated with proteins may be more biologically dangerous than “naked” particles. The article was published in Environmental Science & Technology.

Background of the study

• Micro- and nanoplastics (MNPs) are already found in human tissues, including the brain. In 2024-2025, independent groups confirmed the presence of MNPs in the liver, kidneys, and brain of deceased people, and showed increasing concentrations over time. A separate study found microplastics in the olfactory bulb, indicating a nasal “bypass” to the CNS.
• How Particles Get into the Brain. In addition to the olfactory tract, numerous animal studies and reviews indicate the possibility of micro-nanoplastics crossing the blood-brain barrier (BBB) with subsequent neuroinflammation and dysfunction of the nervous tissue.
• The "protein corona" determines the biological identity of the particles. In biological environments, the surfaces of nanoparticles are quickly covered with adsorbed proteins (protein corona), and it is the corona that determines which receptors "recognize" the particle, how it is distributed among organs, and how toxic it is. This is well described in nanotoxicology and is increasingly being transferred to micro-/nanoplastics.
• What was known about neurotoxicity so far. In vivo experiments and reviews have linked MNP exposure to increased BBB permeability, microglial activation, oxidative stress, and cognitive impairment; however, mechanistic data at the proteome level specifically in human neurons and microglia have been limited.
• What kind of “hole” does a new paper from Environmental Science & Technology fill? The authors systematically compared the effects of microplastics “crowned” with serum proteins versus “naked” particles on the proteome of neurons and microglia for the first time, showing that it is the corona that amplifies unfavorable shifts in fundamental cellular processes. This brings the environmental problem of MNP closer to specific molecular mechanisms of risk for the brain.
• Why is this important for risk assessment? Laboratory tests of plastic toxicity without taking corona into account may underestimate the danger; it is more correct to model the impact of particles in the presence of proteins (blood, cerebrospinal fluid), which is already recommended by review papers.

What exactly did they do?

• In the laboratory, microplastics were incubated in mouse serum to form a protein “crown” on the surface of the particles, then the particles were exposed to brain cells: cultured neurons (mouse) and microglia (human line). After exposure, the cells’ proteome was examined using mass spectrometry.
• For comparison, the effect of "naked" microplastic (without the crown) was also assessed. This made it possible to determine what proportion of the toxic signal is brought by the protein shell on the particle.

Key Results

• The protein corona changes the “personality” of the plastic. As expected by the laws of nanotoxicology, the microparticles adsorb a heterogeneous layer of proteins in the serum. Such complexes caused much more pronounced shifts in protein expression in brain cells than “naked” particles.
• Hitting the basic processes of the cell. With "crowned" microplastics, components of the RNA translation and processing machinery were reduced, lipid metabolism pathways were shifted, and nucleocytoplasmic transport was disrupted - that is, the "fundamental" functions of survival and plasticity of the nerve cell suffered.
• Switching on inflammation and recognition. The authors described the activation of inflammatory programs and cellular particle recognition pathways, which may contribute to the accumulation of microplastics in the brain and chronic irritation of the brain's immune cells.

Why is this important?

• In real life, micro- and nanoplastics are almost never “naked”: they are immediately covered with proteins, lipids, and other environmental molecules—a corona that determines how the particle interacts with cells, whether it passes the blood-brain barrier, and which receptors “see” it. The new work directly shows that it is the corona that can enhance neurotoxic potential.
• The context adds to the alarm: independent studies have found microplastics in the human olfactory bulb and even increased levels in the brains of deceased people; reviews discuss BBB penetration pathways, oxidative stress and neuroinflammation.

How does this compare to previous data?

• It has long been described for nanoparticles that the composition of the corona dictates the "biological identity" and capture by macrophages/microglia; a similar array of data is being collected for microplastics, including works on the effect of the corona from the gastrointestinal tract/serum on cellular capture. The new article is one of the first detailed proteomic analyses specifically in brain cells.

Restrictions

• This is an in vitro cell model: it shows the mechanisms, but does not directly answer questions about dose, duration and reversibility of effects in the body.
• Specific types of particles and protein corona were used; in a real environment, the composition of the corona changes (blood, cerebrospinal fluid, respiratory mucus, etc.), and with it, the biological effects. Animal models and biomonitoring in humans are needed.

What this might mean for risk assessment and policy

• Plastic toxicity test systems must include a “corona” stage in relevant biofluids (blood, cerebrospinal fluid), otherwise we underestimate the risk.
• For regulators and industry, this is an argument to reduce microplastic emissions, accelerate the development of materials with lower affinity for protein coronas, and invest in monitoring plastics in food, air, and water. The reviews emphasize that standardization of measurements and corona accounting are immediate priorities.

What the reader should do today

• Reduce contact with sources of microplastics: choose filtered tap water over bottled water, avoid heating food in plastic if possible, wash synthetics on low cycles/with microfiber filters. (These tips are not taken from the article, but are consistent with current risk reviews.)

Source: Ashim J. et al. Protein Microplastic Coronation Complexes Trigger Proteome Changes in Brain-Derived Neuronal and Glial Cells. Environmental Science & Technology.https://doi.org/10.1021/acs.est.5c04146