Molecular hydrogen in human breath: a new strategy for selectively diagnosing peptic ulcer disease, non-ulcerous dyspepsia and Helicobacter pylori infection

Abstract

The gastric pathogen Helicobacter pylori utilizes molecular hydrogen (H2) as a respiratory substrate during colonization in the gastric mucosa. However, the link between molecular H2 and the pathogenesis of peptic-ulcer disease (PUD) and non-ulcerous dyspepsia (NUD) by the enzymatic activity of H. pylori still remains mostly unknown. Here we provide evidence that breath H2 excretion profiles are distinctly altered by the enzymatic activity of H. pylori for individuals with NUD and PUD. We subsequently unravelled the potential molecular mechanisms responsible for the alteration of H2 in exhaled breath in association with peptic ulcers, encompassing both gastric and duodenal ulcers, along with NUD. We also established that carbon-isotopic fractionations in the acid-mediated bacterial environment regulated by bacterial urease activity cannot discriminate the actual disease state i.e. whether it is peptic ulcer or NUD. However, our findings illuminate the unusual molecular H2 in breath that can track the precise evolution of PUD and NUD, even after the eradication of H. pylori infection. This deepens our understanding of the pathophysiology of PUD and NUD, reveals non-invasively the actual disease state in real-time and thus offers a novel and robust new-generation strategy for treating peptic-ulcer disease together with non-ulcer related complications even when the existing (13)C-urea breath test ((13)C-UBT) fails to diagnose.

Exploring Triple-Isotopic Signatures of Water in Human Exhaled Breath, Gastric Fluid, and Drinking Water Using Integrated Cavity Output Spectroscopy

“…We enrolled 58 human subjects within the age group of 15−66 years [male = 38, female = 20] with a variety of GI deformations such as gastritis, duodenal and gastric ulcer, erosion, etc. Based on their medical reports involving gastrointestinal (GI) endoscopy and biopsy-based rapid urease test (RUT) along with 13 C-urea breath test ( 13 C-UBT), we classified all of the subjects under study in two different groups: H. pylori positive (n = 42) and H. pylori negative patients (n = 16). The detailed information on the subjects and their corresponding medical reports and test results has been provided here in the Supporting Information, Tables S1 and S2.…”

“…The oral breath sample was initially passed through a dead-space volume (∼150 mL) of the bag and subsequently the end-tidal breath was stored in a ∼750 mL reservoir bag utilizing a one-way valve. Thereafter, within 1−2 days, the 13 C-UBT was performed on the patients and they were instructed to follow an overnight fasting (10−12 h). To perform the 13 C-UBT on the patients, at first, a baseline breath sample was collected following ingestion of 4 g of citric acid dissolved in 200 mL of drinking water.…”

“…Several lines of evidence also confirmed that the pathogen Helicobacter pylori ( H. pylori ) is the prime cause of various deformations in the mucosal surface of the GI tract, and this infection, as a worldwide healthcare problem, has received enormous attention. ,, However, studies in the past decade also revealed the models of enzymatic action of hydrogenase which produces molecular hydrogen and subsequently catalyzes the exchange of hydrogen isotopes between water and molecular hydrogen: H 2 (gas) + HDO (liquid/vapor) ⇌ HD + H 2 O. , It is also known that H. pylori contains different membrane-bound hydrogenase enzymes . However, to date there is no direct experimental evidence of the potential link between H. pylori infection and isotopic fractionation of water in the human body.…”

Isotope selective activation: a new insight into the catalytic activity of urease

“…3 Urease is also a potent virulence factor in certain pathogens and is particularly known for its potential link to human diseases like peptic ulcers and stomach cancer. 3,4 Moreover, this enzyme acts as a unique catalyst for its very specic action on urea [CO(NH 2 ) 2 ] and subsequently has found widespread applications in enzymatic assays and as urea sensors for routine clinical measurements of urea in blood, urine and different body uids. 5,6 Besides this, it is also widely used in waste water treatment for removal of urea 5 and as a model enzyme for the study of enzymatic kinetics.…”

“…5 The urease-catalyzed hydrolysis of urea has extensively been studied in the past. 5,7 Urease catalyzes the hydrolysis of urea to produce ammonium carbamate [H 2 NCO 2 NH 4 ] which rapidly decomposes into bicarbonate [HCO 3 À ] and ammonium ions [NH 4 + ] in a non-enzymatic and buffer-mediated system. The bicarbonate nally gets converted into carbon dioxide (CO 2 ).…”