Arsenic-stimulated liver sinusoidal capillarization in mice requires NADPH oxidase–generated superoxide
Adam C. Straub, … , Donna B. Stolz, Aaron Barchowsky
Adam C. Straub, … , Donna B. Stolz, Aaron Barchowsky
Published November 13, 2008
Citation Information: J Clin Invest. 2008;118(12):3980-3989. https://doi.org/10.1172/JCI35092.
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Research Article Hepatology

Arsenic-stimulated liver sinusoidal capillarization in mice requires NADPH oxidase–generated superoxide

Abstract

Environmental arsenic exposure, through drinking contaminated water, is a significant risk factor for developing vascular diseases and is associated with liver portal hypertension, vascular shunting, and portal fibrosis through unknown mechanisms. We found that the addition of low doses of arsenite to the drinking water of mice resulted in marked pathologic remodeling in liver sinusoidal endothelial cells (SECs), including SEC defenestration, capillarization, increased junctional PECAM-1 expression, protein nitration, and decreased liver clearance of modified albumin. Furthermore, the pathologic changes observed after in vivo exposure were recapitulated in isolated mouse SECs exposed to arsenic in culture. To investigate the role of NADPH oxidase–generated ROS in this remodeling, we examined the effect of arsenite in the drinking water of mice deficient for the p47 subunit of the NADPH oxidase and found that knockout mice were protected from arsenite-induced capillarization and protein nitration. Furthermore, ex vivo arsenic exposure increased SEC superoxide generation, and this effect was inhibited by addition of a Nox2 inhibitor and quenched by the cell-permeant superoxide scavenger. In addition, inhibiting either oxidant generation or Rac1-GTPase blocked ex vivo arsenic-stimulated SEC differentiation and dysfunction. Our data indicate that a Nox2-based oxidase is required for SEC capillarization and that it may play a central role in vessel remodeling following environmentally relevant arsenic exposures.

Authors

Adam C. Straub, Katherine A. Clark, Mark A. Ross, Ashwin G. Chandra, Song Li, Xiang Gao, Patrick J. Pagano, Donna B. Stolz, Aaron Barchowsky

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Figure 1

Arsenite-stimulated defenestration and capillarization in vivo and ex vivo.

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Arsenite-stimulated defenestration and capillarization in vivo and ex vi...
(A) Representative scanning EM images were captured from liver sections of control mice or mice exposed for 2 wk to 10–250 ppb arsenite in their drinking water. Morphometric analysis was used to calculate porosity (percent of open space in the fenestrations relative to area of vessel wall) from 10 midlobular sinusoid vessel images from each of 3 separate mice per treatment group. Data are mean ± SD, with significance of differences determined by ANOVA followed by Dunnet’s post test (n = 3 mice per treatment). (B) Primary cultured SECs were exposed ex vivo to arsenite at the indicated concentrations for 8 h. Cells were fixed and processed for scanning EM imaging at ×10,000 magnification. Data are mean ± SD from analysis of 5 images from 5 individual coverslips of cells per treatment (n = 4 mice per treatment). **P < 0.01 versus control. Scale bars: 1 μm.