Proteomic analysis of hydrogen sulfide effect in inflammation. Preliminary study on the effectiveness of sulfureous mineral water inhalation in COPD

Background: Hydrogen sulphide (H2S) is enzymatically generated in various tissues and exerts many physiological effects that suggest its potential role as a regulatory mediator. H2S is involved in the regulation of vascular tone, erectile function, myocardial contractility, inflammation, neurotransmission and insulin secretion. In particular, this gaseous mediator influences the activation of cellular inflammatory processes. On this basis, it is clear the usefulness of molecules able to modulate the plasma and tissue concentration of H2S, especially in the presence of pathologies characterized by the increase in oxidative stress, as occurs in some cardiovascular, metabolic and respiratory diseases. An interesting and certainly innovative approach is the possibility of using molecules capable of slowly releasing H2S in vivo. Taking into account the functional effects of hydrogen sulfide, it is particularly interesting the well-known efficacy of sulfureous inhalation crenotherapy in inflammatory diseases of the respiratory system. Aim: In order to understand the mechanism of the modulatory effect of hydrogen sulfide in inflammation, the proteomic profiling of human neutrophils was performed. The proteome analysis was used to understand the effects of treatments with hydrogen sulfide at the level of protein expression, to study and identify proteins that change the level of expression or undergo post-translational modifications. Furthermore, we investigated the effect of a inhalation crenotherapy cycle with sulfureous waters on a group of patients with COPD evaluating the possible improvement of symptoms and quality of life through the St George’s Respiratory Questionnaire (SGRQ). Materials and Methods: The proteomic analysis on the effects of hydrogen sulfide was carried out on human neutrophils isolated from healthy donors. Extrated cell proteins were resolved by two-dimensional gel electrophoresis and subjected to MALDI mass spectrometry analysis. In the preliminary clinical study, 38 patients with stabilized COPD and 12 healthy smokers and non-smokers were recruited. Patients were treated by one day inhalation with sulfureous bicarbonate calcium water for 12 days. The group was divided into two subgroups, one of which was treated with inhalation by a positive pressure intermittent ventilator and the other subjected to inhalation using conventional aerosol. Results: The proteomic analysis showed in activated neutrophils a high level of expression of the glycolysis enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH) compared to the level of the same enzyme in resting neutrophils. In contrast, a decrease in the amount of GAPDH in activated neutrophils was observed in the presence of hydrogen sulfide. The clinical efficacy of sulfureous crenotherapy was assessed by the administration of the validated SGRQ to test the quality of life in patients with COPD. At the end of sulfureous crenotherapy, we observed a significant reduction of the SGRQ score especially in patients treated with positive pressure ventilation. Conclusions: Interestingly, hydrogen sulfide is able to modulate the functional response of neutrophils by influencing the energy metabolism of activated leukocytes. Based on the clinical efficacy of sulfureous crenotherapy in patients with COPD, it will be worth to investigate whether the same functional changes on the leukocytes of the COPD patients can be observed following the sulfureous crenotherapy.