Activation of endothelial cells after exposure to ambient ultrafine particles: The role of NADPH oxidase

Journal Article · Wed Apr 15 04:00:00 EDT 2009 · Toxicology and Applied Pharmacology

OSTI ID:21272530

Yiqun, Mo; Rong, Wan ^[1]; Sufan, Chien ^[2]; Tollerud, David J ^[1]

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1. Department of Environmental Health and Occupational Health Sciences, School of Public Health and Information Sciences, University of Louisville, 485 E. Gray Street, Louisville, KY 40209 (United States)
2. Department of Surgery, University of Louisville, Louisville, KY (United States)

Several studies have shown that ultrafine particles (UFPs) may pass from the lungs to the circulation because of their very small diameter, and induce lung oxidative stress with a resultant increase in lung epithelial permeability. The direct effects of UFPs on vascular endothelium remain unknown. We hypothesized that exposure to UFPs leads to endothelial cell O{sub 2}{sup {center_dot}}{sup -} generation via NADPH oxidase and results in activation of endothelial cells. Our results showed that UFPs, at a non-toxic dose, induced reactive oxygen species (ROS) generation in mouse pulmonary microvascular endothelial cells (MPMVEC) that was inhibited by pre-treatment with the ROS scavengers or inhibitors, but not with the mitochondrial inhibitor, rotenone. UFP-induced ROS generation in MPMVEC was abolished by p67{sup phox} siRNA transfection and UFPs did not cause ROS generation in MPMVEC isolated from gp91{sup phox} knock-out mice. UFP-induced ROS generation in endothelial cells was also determined in vivo by using a perfused lung model with imaging. Moreover, Western blot and immunofluorescence staining results showed that MPMVEC treated with UFPs resulted in the translocation of cytosolic proteins of NADPH oxidase, p47{sup phox}, p67{sup phox} and rac 1, to the plasma membrane. These results demonstrate that NADPH oxidase in the pulmonary endothelium is involved in ROS generation following exposure to UFPs. To investigate the activation of endothelial cells by UFP-induced oxidative stress, we determined the activation of the mitogen-activated protein kinases (MAPKs) in MPMVEC. Our results showed that exposure of MPMVEC to UFPs caused increased phosphorylation of p38 and ERK1/2 MAPKs that was blocked by pre-treatment with DPI or p67{sup phox} siRNA. Exposure of MPMVEC obtained from gp91{sup phox} knock-out mice to UFPs did not cause increased phosphorylation of p38 and ERK1/2 MAPKs. These findings confirm that UFPs can cause endothelial cells to generate ROS directly via activation of NADPH oxidase. UFP-induced ROS lead to activation of MAPKs through induced phosphorylation of p38 and ERK1/2 MAPKs that may further result in endothelial dysfunction through production of cytokines such as IL-6. Our results suggest that endothelial oxidative stress may be an important mechanism for PM-induced cardiovascular effects.

• OSTI ID: 21272530
• Journal Information: Toxicology and Applied Pharmacology, Journal Name: Toxicology and Applied Pharmacology Journal Issue: 2 Vol. 236; ISSN TXAPA9; ISSN 0041-008X
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
CATALASE
ENDOTHELIUM
IN VIVO
LUNGS
LYMPHOKINES
MEMBRANES
MITOCHONDRIA
NADP
OXIDASES
OXIDATION
PARTICLES
PERMEABILITY
PHOSPHORYLATION
PHOSPHOTRANSFERASES
STRESSES
TOXICITY