Thirdhand smoke exacerbated H2O2-driven airway responses in A549 cells

INTRODUCTION: Thirdhand smoke (THS) is residual smoke after the cigarette is extinguished and adheres to surfaces. Its re-emission into the air also makes THS a health concern for those who suffer from respiratory diseases. The present study evaluated THS's cytotoxic, oxidative, and inflammatory potential in the H2O2-driven respiratory responses in A549 human airway epithelial cells.
METHODS: Extracted THS from terrycloth exposed to 3R4F cigarettes was assessed via MTT to identify cytotoxicity. The reactive oxygen species (ROS) level was set via DCFDA fluorescence intensity in a flow cytometer, where GSH, MDA level, and CAT activity were assessed spectrophotometrically. IL-6 level is measured via ELISA.
RESULTS: THS 50% (v/v) with significant cytotoxicity in A549 cells up-regulated the intracellular ROS level via right-shifted fluorescence intensity of DCFDA compared to the control (p<0.05), which was also amplified with H2O2 co-treatment. MDA level remarkably increased with THS (p<0.05) whereas both THS and THS+H2O2 led to a notable GSH depletion, increase in CAT activity as well as increase in IL-6 level, which were attenuated with negative control (NAC, 1mM) (p<0.05).
DISCUSSION AND CONCLUSION: The induction of oxidative stress might be defined as an important key event in THS-induced airway toxicity which may contribute to the progression of respiratory diseases.