Polystyrene Microplastics Postpone APAP-Induced Liver Injury through Impeding Macrophage Polarization

Area of Science:

• Environmental toxicology
• Hepatology
• Immunology

Background:

• Polystyrene microplastics (PS MPs) are pervasive environmental contaminants found in numerous organisms.
• Previous research indicates PS MPs can cause damage to cognitive, cardiac, intestinal, and hepatic systems.
• The specific impact of PS MPs on liver regeneration during drug-induced liver injury (DILI) is not well understood.

Purpose of the Study:

• To investigate the effects of PS MPs on liver repair mechanisms in a mouse model of acetaminophen (APAP)-induced liver injury.
• To elucidate the underlying cellular and molecular mechanisms by which PS MPs influence liver regeneration.

Main Methods:

• Mice were pretreated with PS MPs before APAP administration to induce acute liver injury.
• Evaluated parameters included mortality, hepatocyte apoptosis, cell proliferation, and inflammatory responses.
• Immune cell recruitment and macrophage polarization were analyzed using flow cytometry and histological assessments.

Main Results:

• PS MPs pretreatment significantly increased mortality and hepatocyte apoptosis in APAP-induced liver injury.
• Exposure to PS MPs suppressed hepatic cell proliferation and altered the inflammatory milieu.
• While PS MPs recruited neutrophils and macrophages, they delayed the polarization of macrophages towards an anti-inflammatory phenotype, hindering tissue repair.

Conclusions:

• Polystyrene microplastics exacerbate APAP-induced hepatotoxicity and impede liver regeneration.
• Delayed macrophage polarization is identified as a key mechanism underlying PS MP-induced suppression of liver repair.
• These findings highlight the potential health risks associated with PS MP exposure, particularly in individuals with compromised liver function, necessitating their consideration in health risk assessments.