Polystyrene microplastics induce activation and cell death of neutrophils through strong adherence and engulfment

Area of Science:

• Immunology
• Environmental Health
• Toxicology

Background:

• Microplastics (MPs) accumulate in the body and may impair immune function.
• The cellular-level effects of MP exposure on innate immunity are not well understood.

Purpose of the Study:

• To investigate how microplastic exposure affects neutrophil function at the cellular level.
• To determine the impact of polystyrene microplastics on innate immune responses.

Main Methods:

• Experiments with mouse and human neutrophils exposed to polystyrene microplastics.
• Analysis of neutrophil binding, engulfment, inflammatory state, and cell death.
• In vivo studies tracking microplastic distribution and interaction with neutrophils in mice.
• RNA sequencing to analyze gene expression changes in exposed human neutrophils.

Main Results:

• Neutrophils strongly bind and engulf polystyrene microplastics.
• Microplastic exposure induces a proinflammatory state and apoptotic cell death in neutrophils via toll-like receptor signaling.
• Orally administered microplastics reach various organs and are endocytosed by neutrophils.
• Human neutrophils also bind and internalize microplastics, with RNA sequencing showing upregulation of cell death pathways.

Conclusions:

• Microplastic accumulation disrupts neutrophil function, potentially exacerbating inflammatory immune responses.
• This study provides novel insights into the adverse cellular immune responses induced by microplastic exposure.