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Inhal Toxicol. 2016 Aug;28(9):383-92. doi: 10.1080/08958378.2016.1179373. Epub 2016 May 31.

Repeated ozone exposure exacerbates insulin resistance and activates innate immune response in genetically susceptible mice.

Author information

1
a Division of Cardiovascular Medicine , Department of Medicine, University of Maryland School of Medicine , Baltimore , MD , USA .
2
b EPA Great Lakes Clean Air Research Center, Michigan State University , East Lansing , MI , USA .
3
c Boonshoft School of Medicine, Wright State University , Dayton , OH , USA , and.
4
d Davis Heart & Lung Research Institute, Department of Internal Medicine, the Ohio State University , Columbus , OH , USA.

Abstract

BACKGROUND:

Inhaled ozone (O3) has been demonstrated as a harmful pollutant and associated with chronic inflammatory diseases such as diabetes and vascular disorders. However, the underlying mechanisms by which O3 mediates harmful effects are poorly understood.

OBJECTIVES:

To investigate the effect of O3 exposure on glucose intolerance, immune activation and underlying mechanisms in a genetically susceptible mouse model.

METHODS:

Diabetes-prone KK mice were exposed to filtered air (FA), or O3 (0.5 ppm) for 13 consecutive weekdays (4 h/day). Insulin tolerance test (ITT) was performed following the last exposure. Plasma insulin, adiponectin, and leptin were measured by ELISA. Pathologic changes were examined by H&E and Oil-Red-O staining. Inflammatory responses were detected using flow cytometry and real-time PCR.

RESULTS:

KK mice exposed to O3 displayed an impaired insulin response. Plasma insulin and leptin levels were reduced in O3-exposed mice. Three-week exposure to O3 induced lung inflammation and increased monocytes/macrophages in both blood and visceral adipose tissue. Inflammatory monocytes/macrophages increased both systemically and locally. CD4 + T cell activation was also enhanced by the exposure of O3 although the relative percentage of CD4 + T cell decreased in blood and adipose tissue. Multiple inflammatory genes including CXCL-11, IFN-γ, TNFα, IL-12, and iNOS were up-regulated in visceral adipose tissue. Furthermore, the expression of oxidative stress-related genes such as Cox4, Cox5a, Scd1, Nrf1, and Nrf2, increased in visceral adipose tissue of O3-exposed mice.

CONCLUSIONS:

Repeated O3 inhalation induces oxidative stress, adipose inflammation and insulin resistance.

KEYWORDS:

Air pollution; inflammation; insulin resistance; oxidative stress; ozone exposure

PMID:
27240593
PMCID:
PMC4911226
DOI:
10.1080/08958378.2016.1179373
[Indexed for MEDLINE]
Free PMC Article

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