Inhalation of hydrogen gas attenuates airway inflammation and oxidative stress in allergic asthmatic mice

Abstract

Background: Asthma is a worldwide common chronic airway disease that cannot be cured and results in the huge burden in public health. Oxidative stress was considered an important mechanism in the pathogenesis of asthma. Hydrogen gas been demonstrated to function as a novel antioxidant and exert therapeutic antioxidant activity in a number of diseases and the function of this nontoxic gas in asthma was unclear. The purpose of the study aims to examine the effect of inhalation hydrogen gas on the pathophysiology of a mouse model of asthma.

Methods: A murine model of ovalbumin (OVA)-induced allergic airway inflammation was used in this study. Briefly, Mice were sensitized to ovalbumin and received inhalation of 67% high concentration of hydrogen gas for 60 min once a day for 7 consecutive days after OVA or PBS challenge respectively. Lung function was assessed in the apparatus with 4 channels of biological signal system. Morphology and goblet cell hyperplasia were stained by H/E and Periodic acid-Schiff staining. Cytologic classification in the bronchial alveolar lavage fluid (BALF) was analyzed by Wright Giemsa staining. Serum, BALF and lung tissue were collected for biochemical assay. One-way analysis of variance (ANOVA) was used to determine statistical significance between groups. Multiple comparisons were made by Bonferroni's Multiple Comparison Test by using GraphPad Prism 5 software.

Results: Inhalation of hydrogen gas abrogated ovalbumin-induced the increase in lung resistance. Concomitantly, the asthmatic mice showed severe inflammatory infiltration and goblet cell hyperplasia which were reversed by hydrogen gas inhalation. Hydrogen gas inhalation reduced significantly the number of total cells, eosinophils and lymphocytes in BALF. Increased level of IL-4, IL-13, TNF-α and CXCL15 in the BALF and IL-4 in the serum were decreased significantly after inhalation. Hydrogen gas inhalation markedly upregulated the activity of decreased superoxide dismutase and significantly attenuated the increased level of malondialdehyde and myeloperoxidase.

Conclusions: Hydrogen gas inhalation improves lung function and protects established airway inflammation in the allergic asthmatic mice model which may be associated with the inhibition of oxidative stress process. This study provides a potential alternative therapeutic opportunity for the clinical management of asthma.

Keywords: Asthma; Cytokine; Hydrogen gas inhalation; Oxidative stress; Pulmonary function.

Conflict of interest statement

The experiment was repeated for three times. Experimental protocols were approved by the Ethical Committee for Animal Studies of Second Military Medical University, Shanghai, China.Not applicable.The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

Fig. 1

The protocol for the hydrogen gas inhalation experiments in the asthmatic mouse model

Fig. 2

The effect of hydrogen gas inhalation on lung function in the asthmatic mouse model. C: control group (n = 10), A: asthma group (n = 10), AH: asthma plus hydrogen gas inhalation group (n = 10), H: control plus hydrogen gas inhalation group (n = 10). **: vs control group, P < 0.01; #: vs asthma group, P < 0.05

Fig. 3

Morphologic findings and scores of bronchial wall in control animals (C, n = 10), asthmatic mice model (A, n = 10) and asthmatic mice model with hydrogen gas inhalation (AH, n = 10). Staining with haematoxylin-eosin (H&E) solution, periodic acid-Schiff (PAS); magnification 40×)

Fig. 4

The number of total cells, neutrophils, eosinophils, lymphocytes and macrophages in the BALF in control animals (C, n = 10), asthmatic mouse model (A, n = 10), asthmatic mice with hydrogen gas inhalation (AH, n = 10) and control animals with hydrogen gas inhalation (H, n = 10). Statistical comparison between groups was performed using analysis of variance followed by Tukey’s test. * P < 0.05, ** P < 0.01, *** P < 0.001 compared to the control group, # P < 0.05, ## P < 0.01 compared to the asthma group

Fig. 5

The concentration of inflammatory cytokines in the BALF in control animals (C, n = 10), asthmatic mouse model (A, n = 10), asthmatic mice with hydrogen gas inhalation (AH, n = 10) and control animals with hydrogen gas inhalation (H, n = 10). * P < 0.05, ** P < 0.01, *** P < 0.001 compared to the control group, # P < 0.05 compared to the asthma group

Fig. 6

The serum concentration of inflammatory cytokines in control animals (C, n = 10), asthmatic mouse model (A, n = 10), asthmatic mice with hydrogen gas inhalation (AH, n = 10) and control animals with hydrogen gas inhalation (H, n = 10). * P < 0.05, ** P < 0.01, *** P < 0.001 compared to the control group, # P < 0.05 compared to the asthma group

Fig. 7

The levels or activities of SOD, MDA, GSH, CAT, MPO, and 8-OHdG of lung tissue in control animals (C, n = 10), asthmatic mouse model (A, n = 10), asthmatic mice with hydrogen gas inhalation (AH, n = 10) and control animals with hydrogen gas inhalation (H, n = 10). * P < 0.05, ** P < 0.01, *** P < 0.001 compared to the control group, # P < 0.05 compared to the asthma group