Biodiesel and Diesel Exhaust Particles Are Cause of Oxidative Stress,Inflammatory Response,Impaired Phagocytosis,and DNA Damage in Airway

Abstract

Background:

Biodiesel is considered as a sustainable alternative for fossil fuels such as diesel. However, the current knowledge on the impact of biodiesel emissions on human health is limited. The respiratory system is the first target organ of inhaled toxicants. Therefore, in this current study we compared the effects of petro-diesel (DEP) and biodiesel exhaust particles (BDEP).

Methods:

The bronchial mucosa models were developed using human primary bronchial epithelial cells (PBEC) in presence or absence of THP-1 cell-derived macrophages (MQ). The cell culture model at air liquid interface (ALI) PBEC-ALI, MQ-ALI, and PBEC co-cultured with MQ (PBEC-ALI/MQ) were exposed to BDEP and DEP exposures (18 and 36 µg/cm²) as well as the corresponding sham exposure (control). Within each group, the comparisons between control and BDEP/DEP exposure at different doses were assessed by Friedman test and followed by Wilcoxon signed rank t test. The study was approved by institutional ethical review board.

Results:

Following exposure to both BDEP and DEP (18 and 36 µg/cm²), both reactive oxygen species and heat shock protein 60 were upregulated in PBEC-ALI and MQ-ALI. Expression of both pro-inflammatory and anti-inflammatory macrophage polarization markers were increased in MQ-ALI against both BDEP and DEP exposure. Phagocytosis activity of MQ was downregulated in MQ-ALI. Increased transcript and secreted protein levels of CXCL8, as well as IL6 and TNFα were detected against both BDEP and DEP exposure (18 and 36 µg/cm²) in PBEC-ALI. Furthermore, the cyclooxygenase-2 (COX-2) mediated histone phosphorylation and DNA damage were increased in PBEC-ALI following exposure to BDEP and DEP (18 and 36 µg/cm²). A COX-2 inhibitor reduced the level of prostaglandin E2, histone phosphorylation and DNA damage in PBEC-ALI following exposure to both concentration of BDEP and DEP.

Conclusions:

Our findings confirm the need to expand the toxicological knowledge of emissions from different biofuels and blends, to better include health impacts of air pollution in the overall sustainability assessment of emerging fossil-free solutions