PM2.5 promotes plaque vulnerability at different stages of atherosclerosis and the formation of foam cells via TLR4/MyD88/NFκB pathway.

Abstract

Clinical evidence has shown an elevated myocardial infarction (MI) risk after PM2.5 (particulate matter < 2.5 μm) exposure. Incident MI may result from rupture of vulnerable plaques. To test whether PM2.5 could promote plaque vulnerability, we exposed PM2.5 to apoe-/- mice by intranasal instillation. We detected the lipid, collagen, macrophage and smooth muscle cells (SMCs) content, and fibrous cap thickness to evaluate the plaque vulnerability. Plaques in HFD-fed mice with PM2.5 treatment for 24 weeks had increased lipid content and macrophage recruitment, and reduced collagen content, fibrous cap thickness and SMCs infiltration. Besides, 4-week exposure to PM2.5 could reduce the fibrous cap thickness, collagen content, but increase the macrophage infiltration and SMCs loss in a rapid atherosclerosis model. In existing plaques, PM2.5 could also decrease the fibrous cap thickness, collagen content. In RAW264.7, PM2.5 could promote the transformation of macrophage into foam cells. The expression of TLR4/MyD88/NFκB and CD36 were upregulated by PM2.5 treatment. Besides, the expression of CD36 promoted by PM2.5 was downregulated by the TLR4 inhibitor or MyD88/NFκB SiRNA. In conclusion, our data indicated that short- and long-term PM2.5 exposure increased plaque vulnerability. The underlying mechanism might be the PM2.5-enhanced formation of foam cells via TLR4/MyD88/NFκB pathway.

• Authors: Jin Geng, Haiyun Liu, Peibing Ge, Tingting Hu, Yanchun Zhang, Xiwen Zhang, Biao Xu, Bingjian Wang, Jun Xie
• Journal: Ecotoxicology and environmental safety (Ecotoxicol Environ Saf) Vol. 176 Pg. 76-84 (Jul 30 2019) ISSN: 1090-2414 [Electronic] Netherlands
• PMID: 30921699 (Publication Type: Journal Article)
• Copyright: Copyright © 2019 Elsevier Inc. All rights reserved.

Chemical References

• Apolipoproteins E
• CD36 Antigens
• Myeloid Differentiation Factor 88
• NF-kappa B
• Particulate Matter
• Toll-Like Receptor 4

Topics

• Air Pollution (adverse effects)
• Animals
• Apolipoproteins E (metabolism)
• Atherosclerosis (pathology)
• CD36 Antigens (metabolism)
• Foam Cells (drug effects)
• Macrophages (drug effects, metabolism)
• Mice
• Myeloid Differentiation Factor 88 (metabolism)
• Myocytes, Smooth Muscle (drug effects)
• NF-kappa B (metabolism)
• Particle Size
• Particulate Matter (chemistry, toxicity)
• Plaque, Atherosclerotic (metabolism, pathology)
• Toll-Like Receptor 4 (metabolism)