Hydrogen gas (XEN) inhalation ameliorates airway inflammation in asthma and COPD patients.
Summary
Background
Hydrogen was proven to have anti-oxidative and anti-inflammation effects to various diseases.
Aim
We wish to investigate the acute effects of inhaled hydrogen on airway inflammation in patients with asthma and chronic obstructive pulmonary disease (COPD).
Methods
In total, 2.4% hydrogen containing steam mixed gas (XEN) was inhaled once for 45 min in 10 patients with asthma and 10 patients with COPD. The levels of granulocyte-macrophage colony stimulating factor, interferon-γ, interleukin-1β (IL-1β), IL-2, IL-4, IL-6 and so on in peripheral blood and exhaled breath condensate (EBC) before and after ‘XEN’ inhalation were measured.
Results
45 minutes ‘XEN’ inhalation once decreased monocyte chemotactic protein 1 level in both COPD (564.70–451.51 pg/mL, P = 0.019) and asthma (386.39–332.76 pg/mL, P = 0.033) group, while decreased IL-8 level only in asthma group (5.25–4.49 pg/mL, P = 0.023). The level of EBC soluble cluster of differentiation-40 ligand in COPD group increased after inhalation (1.07–1.16 pg/mL, P = 0.031), while IL-4 and IL-6 levels in EBC were significantly lower after inhalation in the COPD (0.80–0.64 pg/mL, P = 0.025) and asthma (0.06–0.05 pg/mL, P = 0.007) group, respectively.
Conclusions
A single inhalation of hydrogen for 45 min attenuated inflammatory status in airways in patients with asthma and COPD.
Introduction
Hydrogen, identified as antioxidants, in particular have been shown to have distinct characteristics, including its effect on specific reactive oxygen species (ROS) and excellent diffusion capacity.1 It has been demonstrated that hydrogen could provide protection against various diseases, including sepsis, stroke and ischemia-reperfusion injury.2,3 The major feature of chronic obstructive pulmonary disease (COPD) and other airway diseases is generally regarded as abnormal response to injury, chronic inflammation, excessive activation of macrophages, neutrophils, T lymphocytes and fibroblasts in the lung and oxidative stress is widely proposed as a pathogenic mechanism while ROS plays a pivotal role in the incidence and exacerbation of diseases.4 It is still unknown, however, whether hydrogen with low concentration inhalation has a therapeutic role on human diseases with airflow limitation. The purpose of this study was to investigate the effect of inhaled hydrogen gas on airway inflammation in patients with COPD and asthma.
Methods
Subjects
From March 2019 to June 2019, 10 COPD and 10 asthma patients (aged 20–65 years old) were recruited to participate in this study in Peking Union Medical College Hospital. COPD patients were restricted to those with spirometrically confirmed airflow obstruction (postbronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) < 0.7).5 Asthma patients met the diagnostic criteria of asthma.6 Oxygen saturation on resting-state using pulse oximetry and Medical Research Council (MRC) scores for dyspnea were recorded.7 Exclusion criteria included pregnancy, breast feeding, symptoms of acute airway infections or exacerbation 4 weeks prior to the test, and past history of malignancy, myocardial infarction, liver cirrhosis, renal failure and mental or intellectual disorders who were judged to not be able to provide informed consent.
The study protocol was reviewed and approved by the ethical committee of the Peking Union Medical College Hospital (HS-1948), and the protocol was carried out in accordance with relevant ethical guidelines and regulations. The written consents were obtained from all subjects.
Pulmonary function
Pulmonary function was measured by FEV1, FVC, FEV1/FVC and bronchial provocation test used a MasterScreen spirometer (CareFusion, Hoechberg, Germany). All measurements were performed according to the standards established by the American Thoracic Society.8
Hydrogen gas administration
A machine developed by Earth Engineering Co. (Suisonia, FRJ-003, Kitakyushu, Japan) was used to decompose superheated steam to produce a mixed gas containing hydrogen (H2) gas. The stream produced by heating sterile water for inhalation, and it decomposes into H2 and oxygen (O2) at a decomposition ratio of 67% vs. 33%. As air is present inside the machine, the concentration of H2 gas is ∼2.4%, according to the Manufacture’s instruction confirmed by a portable type hydrogen detector. After transfer through nasal cannula the H2 concentration is ∼0.1–0.3% when inhaled, while O2 is adsorbed with a cartridge. This steam mixed gas is designated as ‘XEN’ in preliminary study. All subjects performed the hydrogen gas inhalation for 45 min under close observation of researchers to ensure the compliance and to find any adverse reactions.
Exhaled breath condensate (EBC) from all participants was obtained according to the American Thoracic Society/European Respiratory Society guidelines using RTube™ (Respiratory Research, Inc, Austin, TX, USA) by breathing tidally into the device precooled to −20°C. Before and after 45 min of ‘XEN’ inhalation, peripheral blood and EBC were collected and storage in −80°C.
Reagents and measurement
MILLIPLEX MAP assay beads are comprised of polystyrene microspheres that have been impregnated with ferrite particles as well as a mixture of two colored dyes. The level of granulocyte-macrophage colony stimulating factor, interferon-γ, interleukin-1β (IL-1β), IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-13, IL-17A, macrophage inflammatory protein-1α (MIP-1α), MIP-1β, tumor necrosis factor alpha (TNF-α) were detected by multiplex analysis using T Cell Magnetic Bead Panel (HSTCMAG-28SK-14) and macrophage-derived chemokine, soluble cluster of differentiation-40 ligand, monocyte chemotactic protein 1 (MCP-1), vascular endothelial growth factor A using Human Cytokine/Chemokine Magnetic Bead Panel (HCYTOMAG-60K-04) (EMD Millipore Corp, Billerica, MA, USA). Luminex® xMAP® technology was used for detection and analysis concentrations of multiple target cytokine in a single sample, as recommended by the manufacturer. Sandwich enzyme-linked immunosorbent assay was used to measure the level of human superoxide dismutase 3 (SOD3) using LF-EK0107 kit (AbFrontier, Seoul, South Korea).
Statistical analysis
Statistical analysis was performed using SPSS 19.0 software (SPSS Inc, Chicago, IL, USA). Values were presented as the mean ± the standard deviation and the Shapiro–Wilk Test was used to assess the normal distribution of data. To compare the mean of a single group before and after ‘XEN’ inhalation, paired samples t test after taking natural logarithms were performed and statistical significance was established at P < 0.05.
Results
The characteristics of the subjects
The characteristics of the 20 subjects are listed in Table 1. Patients with COPD were older, with more male participates than asthma group. Pulmonary function showed COPD patients had lower levels in FEV1, FVC and FEV1/FVC compared with asthma patients (P < 0.05).
COPD (N = 10) | Asthma (N = 10) | P value | |
Age, years (range) | 61.9±5.9 (52–70) | 46.8±13.3 (21–64) | 0.006* |
Sex (M/F) | 10/0 | 3/7 | 0.001* |
BMI (kg/m2) | 25.30±3.02 | 24.32±3.01 | 0.499 |
Pack-years | 36.9±12.9 | 8.2±7.2 | 0.001* |
Oxygen saturation (%) | 95.0±1.9 | 96.3 ±1.1 | 0.098 |
mMRC of dyspnea | 3.3±1.0 | 1.7±0.8 | 0.001* |
FEV1 (%pred) | 46.08±16.21 | 74.32±27.34 | 0.016* |
FVC (%pred) | 79.50±13.45 | 96.36±12.87 | 0.014* |
FEV1/FVC, % | 45.55±13.58 | 74.06±15.10 | 0.001* |
Sex ratio were compared using Pearson Chi-square test. Quantitative data are expressed as mean ± SD, and P values were obtained by the independent sample t test.
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