Tiron is Protective Against ROS-Induced Damage in Human Bronchial Epithelial Cells

Abstract

Background Reactive oxygen species (ROS)-induced damage and resultant oxidative stress have been documented within the lung and have been implicated in the development of pulmonary diseases such as chronic obstructive pulmonary disorder and asthma (1). Antioxidant supplementation has been used to inhibit accumulation of oxidative damage such as DNA strand breaks and lipid peroxidation in inflammation (1,2). Tiron, a superoxide scavenger, has previously been shown to reduce murine airway remodelling and associated inflammation as well as offer protection against UV and H2O2-induced mitochondrial DNA (mtDNA) damage in human dermal fibroblasts (2,3). Aim This study aimed to investigate the use of the Tiron to prevent ROS-induced damage in human bronchial epithelial cells (BEAS-2B). Methods BEAS-2B cells were pre-treated with 3mM Tiron in BEGM (Lonza, UK) for 24 hours prior to induction of ROS damage (1 hour H2O2 (0.25mM) or exposure to 120 hour hypoxic (1% O2) conditions). Simultaneous Tiron treatment and ROS-induction was also assessed. The level of ROS production was assessed via flow cytometric analysis using the DCFDA assay (Abcam, UK). MtDNA strand breaks were assessed using a qPCR 1kb amplification following 83bp alignment (4). Concentration of the lipid peroxidation biomarker malondialdehyde (MDA) was quantified using a colourimetric assay (Sigma, UK). All data was normalised to the cell controls where appropriate and summarised as mean ±SEM, analysed by one-way ANOVA and Dunnett’s posthoc test (p≤0.05). Results Both pre-treatment and the addition of Tiron at the time of ROS-induction demonstrated 100% protection (±0.18 vs. H2O2; ±0.06 vs. hypoxia pre-treatment and ±0.30 co-treatment) against both H2O2 and hypoxia induced mtDNA strand breaks. This was supported by a significant (p≤0.001) reduction in the production of ROS and diminished formation of MDA with both H2O2 and hypoxic conditions compared to untreated controls. Conclusion This study demonstrates a promising use for Tiron as a supplement against both H2O2 and hypoxia-induced ROS in BEAS-2B cells. However, the precise mechanism of Tiron’s action requires further elucidation. The findings of this study indicate a potential use for Tiron in the treatment and prevention of pulmonary diseases associated with oxidative stress.