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Inducing Acute Lung Injury in Mice by Direct Intratracheal Lipopolysaccharide Instillation
Published on: July 6, 2019
Inhalation of Microplastics Induces Inflammatory Injuries in Multiple Murine Organs via the Toll-like Receptor
Qing Xia1, Yuan Wei1, Long-Ji Hu1
1Department of Environmental Health, School of Public Health, China Medical University, Shenyang 110122, P. R. China.
Abstract:
Previous studies have detected microplastics (MPs) in human biological samples, such as lungs, alveolar lavage fluid, and thrombus. However, whether MPs induce health effects after inhalation are unclear. In this study, fluorescent polystyrene microplastics (PS-MPs) were found in the thymus, spleen, testes, liver, kidneys, and brain on day 1 or day 3 after one intratracheal instillation. Furthermore, mice showed inflammation in multiple organs, manifested as obvious infiltration of neutrophils and macrophages, increased Toll-like receptors (TLRs), myeloid differentiation primary response protein 88 (MyD88) and nuclear factor-κB (NF-κB), as well as proinflammatory cytokines (tumor necrosis factor (TNF)-α and interleukin (IL)-1β) in the lungs, thymus, spleen, liver, and kidneys after four intratracheal instillations of PS-MPs at once every 2 weeks. Hepatic and renal function indexes were also increased. Subsequently, the inflammatory response in multiple murine organs was significantly alleviated by TLR2 and TLR4 inhibitors. Unexpectedly, we did not find any elevated secretion of monocyte chemotactic protein (MCP)-1 or TNF-α by RAW264.7 macrophages in vitro. Thus, PS-MPs induced inflammatory injuries in multiple murine organs via the TLRs/MyD88/NF-κB pathway in vivo, but not macrophages in vitro. These results may provide theoretical support for healthy protection against PS-MPs and their environmental risk assessment.
Insights
Polystyrene microplastics (PS-MPs) accumulate in multiple organs and cause inflammation via the Toll-like receptor (TLR) pathway in mice. These findings highlight potential health risks associated with microplastic exposure.
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.
