The protective potential of Tiron in models of direct and physiologically induced reactive oxygen species

Abstract

Reactive oxygen species (ROS) derived damage and accompanying oxidative stress have been identified in a number of pathological conditions. As a result, antioxidant supplementation has been increasingly investigated to reduce ROS and inhibit the accumulation of oxidative damage. Tiron, 4,5-Dihydroxy-1,3-benzenedisulfonic acid disodium salt monohydrate, is a synthetic vitamin E analogue first characterised in 1964. Described chemically as a spin trap, Tiron has also been considered a superoxide scavenger and previously shown to alleviate oxidative stress to a high degree in human skin cells.

This thesis aimed to evaluate the use of Tiron comparatively to protect against ROS-induced damage in three different human immortalised cell lines. Renal proximal epithelial tubular (HKC-8), bronchial epithelial cells (BEAS-2B) and astroglial (SVGp12) cells were pre-treated with Tiron for 24 hours prior to the induction of ROS with H2O2or an optimised physiological method through exposure to high glucose or hypoxia. Protection against ROS-induced damage in all models was assessed through the measurement of ROS, mitochondrial DNA (mtDNA)strand breaks and malondialdehyde (MDA) concentration. The effects of prolonged exposure to Tiron, co-treatment at the time of ROS induction and Tiron’s influence on Nrf2 protein expression were also investigated.

Tiron pre-treatment was significantly protective against ROS-induced mtDNA strand breaks, significantly reduced ROS and MDA levels and was independent of the Nrf2 pathway in all cell lines. Co-treatment with Tiron was also significantly protective in HKC-8 and BEAS-2B cells. However, prolonged supplementation with Tiron led to a significant increase in Nrf2 protein expression across all cell lines, providing some insight into its mechanism.

Overall, this thesis demonstrates a promising use for Tiron supplementation in the protection against ROS damage, building upon previously published literature of Tiron’s use as a ROS reducing agent. The finding that Tiron consistently offered significantly high degrees of protection independent of cell type and pre-or co-treatment methods in models of both direct and physiologically-induced ROS indicates the therapeutic potential of this ROS reducing agent. Further studies are now required to support the use of Tiron in disease-specific models before clinical translation.

Date of Award	Sept 2019
Original language	English
Awarding Institution	Coventry University