Antioxidant Effect of Sulphurous Thermal Water on Human Neutrophil Bursts: Chemiluminescence Evaluation

Abstract

Background: The activities of the HS (sulfhydryl or thiolic) group in the cysteine of glutathione or various low-weight soluble molecules (thiolic drugs), such as N-acethylcysteine, mesna, thiopronine and dithiotreitol or stepronine and erdosteine (prodrugs), include its antioxidant activity in the airways during the release of reactive oxygen or nitrogen species (ROS, RNS) by polymorphonuclear neutrophils (PMNs) activated in response to exogenous or endogenous stimuli. Objective: In addition to being administered by means of thiolic molecules, the HS group can also be given by means of the inhalation of sulphurous thermal water. The aim of this study was to investigate the effect of sulphurous thermal water on the release of ROS and RNS during the bursts of human PMNs. Methods: The luminol-amplified chemiluminescence methodology was used to investigate the ROS and RNS released by PMNs stimulated with N-formyl-methionyl-leucyl-phenylalanine and phorbol-12-myristate-13-acetate, before and after incubation with sulphurous water. Effects on cell-free systems were also investigated. Results: The water significantly reduced the luminol-amplified chemiluminescence of N-formyl-methionyl-leucyl-phenylalanine- andphorbol-12-myristate-13-acetate-activated PMNs on average from 0.94 to 15.5 µg/ml of HS, even after the addition of L-arginine, a nitric oxide (NO) donor. Similar findings have also been obtained in a cell-free system, thus confirming the importance of the presence of the HS group (reductive activity). Conclusions: The positive effects of the activity of sulphurous thermal waters has been partially based on the patients’ subjective sense of wellbeing and partially on not always easy to quantify symptomatic (or general) clinical improvements. Our findings indicate that, in addition to their known mucolytic activity and trophic effects on respiratory mucosa, the HS groups present in the sulphurous thermal water of this spring also have antioxidant activity that contributes to the therapeutic effects of the water in upper and lower airway inflammatory diseases.