In situ pulmonary localization of air pollution particle-induced oxidative stress

Exposure to air particulate matter (PM) may be associated with increased morbidity and mortality. An improved understanding of the mechanism(s) by which PM induces adverse effects is needed. This preliminary study examined the ability to use unique bioluminescent technologies to identify acute localized areas of residual oil fly ash (ROFA)-induced, oxidative lung injury. Transgenic mice, in which luciferase (luc) expression was regulated by the heme oxygenase (HO)-1 promoter, were exposed by pharyngeal aspiration to either saline or 50 microg ROFA/mouse. HO-1-luc expression was determined at 2, 6, 12, and 24 h postexposure using luminescent quantification and Western blot analysis of lung protein extracts, as well as with a novel in situ pulmonary bioluminescence imaging approach. The different approaches for the detection of luciferase in lung protein extracts recovered from ROFA exposed HO-1-luc transgenic mice gave variable results. Pulmonary homogenate HO-1-luc levels were increased at 2 h and 24 h postexposure to ROFA when examined by chemilumescent and Western blot analyses, respectively. In situ bioluminescent imaging of pulmonary tissue sections detected ROFA-induced pulmonary luciferase expression by identifying highly localized increases in HO-1-luc expression at 12 h and 24 h postexposure. These results suggest that the variability observed in the methods of detection for luciferase may be due to a localization of cells expressing luciferase within tissue samples, demonstrating that the HO-1-luc transgenic mouse model is the preferred method to detect and pinpoint in vivo particle-induced, oxidative lung injury. The feasibility of using this in situ approach is a unique proof-of-concept application for the identification of localized sites of oxidative injury induced by environmental pollutants.