Inhalation of Microplastics Induces Inflammatory Injuries in Multiple Murine Organs via the Toll-like Receptor...

Area of Science:

• Environmental Health
• Toxicology
• Immunology

Background:

• Microplastics (MPs) are detected in human tissues, but their health effects remain unclear.
• Inhalation is a potential exposure route for MPs, necessitating investigation into respiratory and systemic impacts.

Purpose of the Study:

• To investigate the in vivo distribution and health effects of inhaled polystyrene microplastics (PS-MPs) in mice.
• To elucidate the underlying molecular mechanisms of PS-MP-induced inflammation.

Main Methods:

• Mice were intratracheally instilled with fluorescent PS-MPs.
• Organ distribution, inflammatory markers (neutrophils, macrophages, TLRs, MyD88, NF-κB, cytokines), and organ function were assessed.
• TLR2 and TLR4 inhibitors were used to evaluate their impact on inflammation.

Main Results:

• PS-MPs were found in various organs including the thymus, spleen, liver, kidneys, and brain.
• Inhalation of PS-MPs induced inflammation in multiple organs, characterized by immune cell infiltration and elevated pro-inflammatory cytokines.
• Hepatic and renal function were impaired.
• TLR inhibitors significantly reduced the inflammatory response in vivo.
• No inflammatory response was observed in vitro using RAW264.7 macrophages.

Conclusions:

• PS-MPs induce inflammatory injuries in multiple organs through the TLRs/MyD88/NF-κB pathway in vivo.
• The in vitro macrophage response did not replicate the in vivo findings, suggesting complex biological interactions.
• Results provide evidence for health protection strategies and environmental risk assessment of PS-MPs.