Oligomer nanoparticle release from polylactic acid plastics catalysed by gut enzymes triggers acute inflammation

The health risks of exposure to 'eco-friendly' biodegradable plastics of anthropogenic origin and their effects on the gastrointestinal tract are largely unknown. Here we demonstrate that the enzymatic hydrolysis of polylactic acid microplastics generated nanoplastic particles by competing for triglyceride-degrading lipase during gastrointestinal processes. Nanoparticle oligomers were formed by hydrophobically driven self-aggregation. In a mouse model, polylactic acid oligomers and their nanoparticles bioaccumulated in the liver, intestine and brain. Hydrolysed oligomers caused intestinal damage and acute inflammation. A large-scale pharmacophore model revealed that oligomers interacted with matrix metallopeptidase 12. Mechanistically, high binding affinity (K-d = 13.3 mu mol l(-)(1)) of oligomers to the catalytic zinc-ion finger domain led to matrix metallopeptidase 12 inactivation, which might mediate the adverse bowel inflammatory effects after exposure to polylactic acid oligomers. Biodegradable plastics are considered to be a solution to address environmental plastic pollution. Thus, understanding the gastrointestinal fates and toxicities of bioplastics will provide insights into potential health risks. A large-scale pharmacophore model supported by in vitro ligand-binding studies suggests polylactic acid oligomer toxicity in a mouse model is due to the inhibition of matrix metallopeptidase 12.

Automated summary

The health risks of biodegradable plastics and their effects on the gastrointestinal tract are not well understood. In this study, we found that polylactic acid microplastics generated nanoparticles during gastrointestinal processes. These nanoparticles bioaccumulated in the liver, intestine, and brain of mice, causing intestinal damage and acute inflammation.