THE ROLE OF MITOCHONDRIA IN THE OXIDATIVE RESPONSE OF RAW 264.7 MURINE MACROPHAGES EXPOSED TO AIR POLLUTION PARTICULATE MATTER

CACERES L; PAZ M; MARTINO ADAMI PV; OJEDA D; GARCES M; CALABRO V; TASSAT D.; MORELLI L; ALVAREZ S; GONZALEZ MAGLIO D; MARCHINI T; EVELSON, P

Congreso; Reunion de Sociedades Conjuntas; 2017

The exposure to environmental particulate matter (PM) is associated with pulmonary oxidative stress and inflammation. Alveolar macrophages are suggested to play a central role in this scenario, since they produce inflammatory mediators and reactive oxygenspecies. The aim of this work was to study the redox status and the role of mitochondria in macrophages after the exposure to Residual Oil Fly Ash (ROFA), a PM surrogate rich in transition metals. The murine cell line RAW 264.7 was exposed to ROFA at 100 μg/mL for24 hs. Cell viability was not significantly affected under these experimental conditions. Intracellular redox status was assessed by flow cytometry as dichlorofluorescein mean fluorescence intensity (MFI), which was increased by 30% following ROFA incubation compared to the control group (p<0.05). Mitochondrial O2 ●- production was determined by MitoSox fluorescent probe, resulting in an increase of 167% (control: 9±4% MitoSox+ cells, p<0.05). Consistently, mitochondrial inner membrane potential decreased by 41% (control: 80±6% TMRM+ cells, p<0.05). Mitochondrial functionality was also assessed by Seahorse XF Analyzer, resulting in an 85% decrease in respiratory control ratio (p<0.05), as well as a 33% decrease in the ATP-O ratio (p<0.05), an indicator of oxidative phosphorylation efficiency, and a 2-fold increase in the H+ leak (p<0.01), an indicator of the mitochondrial inner membrane integrity, following ROFA incubation. Given that we observed a different response with Concentrated Ambient Particles (CAPs), another source of PM, which differs in elemental composition from ROFA, we suggest that PM chemistry