Effects of H2-Rich Water Consumption on Oxidative Stress, PBMC Profiles and Their Transcriptome: A Randomized, Double-blind, Controlled Study

Abstract

Oxidative stress indicates a state where excessive oxidants overwhelm the biological antioxidant system, leading to various pathological conditions such as chronic inflammation and cellular dysfunctions. Recently, molecular H2 has been proposed as a novel antioxidant, and its therapeutic effects against various diseases were demonstrated with animal models and clinical trials. However, the antioxidant effect of the H2 administration has not been examined in the healthy subjects, and its systemic effect has not been elucidated. Here, we aimed to investigate the effects of H2-rich water (HW) consumption in healthy adults through the extensive analysis of antioxidant capacity, immune cell profiles, and transcriptome of peripheral blood mononuclear cells (PBMCs), and to compare the effects of HW consumption with those of plain water (PW) consumption in resting state and exercise-induced oxidative stress state. A total of 38 participants (20-59 y) completed a double-blind, randomized, controlled intervention trial. They consumed either 1.5 L/d of PW (n = 18) or HW (n = 20) for 4 weeks. When the participants were at rest, we measured biological antioxidant potential (BAP), derivatives of reactive oxygen metabolites (d-ROMs), and 8-Oxo-2-deoxyguanosine (8-OHdG) in serum, and also analyzed the apoptosis and subpopulations of PBMCs. At week 4, we conducted the treadmill test to induce acute oxidative stress, and analyzed the level of oxidative stress, peripheral immune cell subpopulations and PBMC transcriptome. In resting state, BAP increased to a greater extent in HW group (n = 10) than in PW group (n = 8) in those who aged ≥30 y (P = 0.028), with no difference between groups in <30 y (P = 0.534). Also, HW group (n = 18) showed a lower percentage of PBMC apoptosis than PW group (n = 18) (P = 0.042) and HW consumption decreased the frequency of CD14 positive PBMCs (P = 0.042). In the exercise-induced oxidative stress state, HW group (n = 18-20) did not significantly differ from PW group (n = 18) in the serum biomarkers of BAP, d-ROMs, and 8-OHdG and in the frequencies of PBMC subpopulations (All P > 0.05). Transcriptome profiling of PBMCs, however, revealed a clearly classified transcriptional response of HW group. Particularly, HW consumption most influenced on the genes belonging to the functional category of inflammatory response and significantly down-regulated the NF-κB signaling pathway. Furthermore, the expression levels of NF-κB responsive genes including IL1B, IL8, IL6R, and TNFRSF10B were significantly lower in HW group. In conclusion, a 4-week HW consumption reduces oxidative stress by improving antioxidant capacity, which leads to the decreases in cellular damages of PBMCs and the frequency of circulating monocytes. In the condition of acute oxidative stress, 4-week HW consumption reduces the inflammatory response by down-regulating NF-κB-mediated signal transduction and NF-κB responsive genes. These findings suggest that the H2 administration exhibits the antioxidant effect in healthy population and our study may help understanding the molecular mechanism by which H2 exhibits the anti-inflammatory effect against intense oxidative stress.