Nanoplastics target lung monocytes, disrupting immune dynamics

Area of Science:

• Environmental Health
• Toxicology
• Immunology

Background:

• Systemic exposure to microplastics and nanoplastics raises concerns regarding their biodistribution and potential human health impacts.
• Understanding nanoplastic interactions with biological systems is crucial for assessing health risks.

Purpose of the Study:

• To investigate the biodistribution and cellular responses to nanoplastics following systemic exposure in female mice.
• To elucidate the specific immune cell types involved in nanoplastic sequestration and the impact on immune cell differentiation.

Main Methods:

• Whole-animal fluorescence imaging to track nanoplastic distribution.
• Flow cytometry and single-cell RNA sequencing to analyze nanoplastic-partitioned cells.
• Monocyte depletion experiments to assess immune cell compensatory mechanisms.

Main Results:

• Nanoplastics predominantly localized to the lung, unlike microplastics or iron nanoparticles.
• Nonclassical monocytes and a subset of CD206- interstitial macrophages in the lung sequestered nanoplastics.
• Nanoplastic sequestration delayed monocyte-to-macrophage transition, indicated by persistent gene expression.
• Monocyte depletion led to compensatory expansion of classical monocytes, which then took up nanoplastics.

Conclusions:

• Nanoplastics perturb monocyte-to-macrophage differentiation in the lung.
• Nanoplastic exposure can reprogram lung immune dynamics, potentially causing immune dysregulation.
• Environmental nanoplastic exposure may pose long-term risks due to immune system interference.