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Cationic Nanoplastics Assemble Lipid A Coronas That Alter TLR4 Signaling and Impair Endotoxin Tolerance
Summary
Tiny plastic particles with a positive charge can stick to harmful bacterial toxins in our bodies and prevent our immune system from recognizing them, which weakens our body's ability to build protection against future infections. This matters because microplastics are everywhere in our environment, and this research shows they might interfere with important immune system processes, especially our natural defense training that happens after exposure to bacteria. Scientists found this effect was strongest with fresh plastics but decreased when plastics broke down from sunlight or mixed with proteins in the digestive system, suggesting the risk may depend on the type and condition of plastic we're exposed to.
Micro- and nanoplastics are pervasive, yet their capacity to modify host recognition of microbial ligands remains incompletely understood. Here we show that amine-functionalized polystyrene nanoplastics (PS-NH 2 ) act as a chemically defined cationic endmember that sequesters lipid A, assembling compact lipopolysaccharide (LPS) coronas that reduce productive engagement of the TLR4-MD-2 complex. Biophysical readouts (DLS, zeta potential, TEM, and UV–vis) and all-atom molecular dynamics support tight coronas driven by cooperative hydrophobic insertion and hydrogen bonding. Functionally, coexposure attenuates MyD88-NF-kB and TRIF-IRF3 signaling in primary human monocytes and in vivo suppresses acute cytokine output and impairs the establishment of endotoxin tolerance during conditioning. In proof-of-principle in vivo conditioning models, PS-NH 2 counteracts LPS-mediated protective effects in type-1 diabetes and house-dust-mite allergy settings. These effects are strongest for the fresh, strongly cationic particle state, are attenuated by UV weathering and gastrointestinal protein-corona formation, and vary with LPS source, particle size, and particle-to-LPS ratio. Together, these findings identify a corona-mediated route by which a defined nanoplastic surface state can alter microbial recognition under controlled coexposure conditions.