Revealing the antibacterial power of hydrogen-releasing PdH nanohydride against drug resistant Staphylococcus aureus: an in-depth mechanism study

Currently, multidrug resistant (MDR) bacterial infections are a great threat to public health, and the development of novel strategies for high efficiency combatting of MDR bacteria is in urgent demand. Hydrogen (H2) is a small gas with a high reducing ability, and plenty of recent studies have demonstrated its therapeutic effect on many diseases. However, the antibacterial effectiveness and mechanism of H2 against MDR bacteria are still unknown. In the present work, using PdH nanohydride with a temperature responsive H2-releasing property as the H2 source, we demonstrated that H2 was not only able to inhibit the growth of normal Staphylococcus aureus (S. aureus), but could also effectively eliminate single drug resistant S. aureus (CRSA) and multidrug resistant S. aureus (MRSA), as well as the biofilms formed by those bacteria. Moreover, an in-depth mechanism regarding the anti-antibiotic-resistance activity of H2 was elucidated by us, in which H2 exerted its antibacterial effect by firstly causing severe membrane damage, followed by boosting generation of intracellular ROS, which subsequently triggered DNA damage and finally led to bacterial death. The proposed mechanism was further verified by genomic analysis, where a cluster of genes related to bacterial membrane integrity, biofilm formation, metabolism and DNA functions was significantly perturbed by the released H2. In particular, H2 boosted intracellular ROS generation by destroying the redox homeostasis of bacterial metabolism. More importantly, we revealed that H2 was able to alleviate the antibiotic resistance of CRSA and MRSA by significantly down-regulating the expression of many drug-resistant genes, e.g. the norG gene of CRSA, and fmtA, gpsB, sarA and marR genes of MRSA, as well as reducing the minimal inhibitory concentration (MIC) of ciprofloxacin/ampicillin against CRSA/MRSA. The findings in our work suggested that H2 therapy is a promising tool for combating antibiotic-resistant bacteria.

Hydrogen-Rich Saline Attenuates Lung Ischemia-Reperfusion Injury in Rabbits

Hydrogen gas, an antioxidant agent, was found to protect against cerebral and myocardial ischemia-reperfusion (I/R) injury. In the present study, we investigated the effect of hydrogen-rich saline (HRS) on the I/R-induced lung injury. Left lung of male New Zealand White rabbits rendered normothermic ischemia for 60 min and reperfused for up to 240 min. Treated animals received intraperitoneal injection of 5 mL/kg HRS or the same volume of normal saline 10 min before the start of reperfusion. Blood and lung tissue samples were obtained for blood gas and biochemical analyses. The tissues obtained from lower lobe of left lung were used for histologic examination. After 240 min of reperfusion, intraperitoneal administration of HRS increased PaO2/FiO2 ratio and superoxide dismutase activities, and decreased malondialdehyde contents, proinflammatory cytokines expression, and myeloperoxidase activities, along with reduced wet/dry ratio and histologic injury scores (P < 0.05 versus I/R group). These results suggest that intraperitoneal administration of HRS before reperfusion protects the lung from I/R injury. The protective effect seems to be closely related to regulating oxidative damage and antioxidant enzyme activities and neutrophil infiltration.

Effect of hydrogen-rich saline on apoptosis induced by hepatic ischemia reperfusion upon laparoscopic hepatectomy in miniature pigs

Hepatic ischemia reperfusion injury (HIRI) occurs commonly in liver surgery and liver transplantation. Hydrogen, a safe and effective antioxidant, exerts a protective effect against liver injury. In this study, we investigated the role of hydrogen-rich saline (HRS) in apoptosis in a miniature pig model of laparoscopic HIRI upon hepatectomy. Bama miniature pigs were randomly assigned to sham, I/R and HRS groups. The pigs received 10 mL/kg HRS by portal venous injection 10 min before reperfusion and at 1 d, 2 d, and 3 d after surgery. The results showed that HRS treatment significantly decreased serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin (TBIL) activity and TUNEL-positive cells. Upon HRS treatment, the expression of P53 and Bax mRNA and protein by RT-qPCR and Western blot was markedly decreased, whereas the expression of bcl-2 mRNA and protein was significantly increased. Moreover, Caspase-3 and Caspase-9 activities were significantly decreased upon treatment with HRS. In conclusion, the results indicate that HRS could alleviate liver injury and improve liver function via inhibiting apoptosis after laparoscopic HIRI and hepatectomy injury in miniature pigs.

Hydrogen-rich saline protects against small-scale liver ischemia-reperfusion injury by inhibiting endoplasmic reticulum stress

Aim: Our research investigated the role of Hydrogen-rich saline (HRS) on the Endoplasmic reticulum stress (ERS) pathway and the effect of HRS on tissue injury in small Bama pig model of hepatic ischemia-reperfusion combined with partial hepatectomy. Main methods: Eighteen healthy Bama miniature pigs were randomly divided equally into three groups: Sham, IRI, and HRS. Laparoscopic technique was employed to establish the model of hepatic ischemia-reperfusion combined with partial hepatectomy. HRS (10mL/kg) was injected into the portal vein 10min before perfusion. Histological examinations of the liver tissues were performed after HE staining. Additionally, transmission electron microscopy was performed to detect liver cell microstructure. Real-time PCR, Western blotting, and immunohistochemical staining were performed to analyze various ERS molecules including GRP78, p-eIF2α, XBP-1s, Full-length ATF6α, p-JNK, ATF4, and CHOP. Key findings: We observed that HRS visibly improved ischemia-reperfusion injury (IRI) by reducing various parameters of ERS stress as evidenced by down-regulation of the mRNA as well as protein levels of GRP78, p-eIF2α, XBP-1s, p-JNK, and CHOP, and reducing the cleavage of Full-length ATF6α. Significance: Our study demonstrates that HRS protects the liver from IRI by inhibiting ERS.

Hydrogen-rich saline protects against hepatic injury induced by ischemia-reperfusion and laparoscopic hepatectomy in swine

Background Hydrogen-rich saline (HRS) has antioxidative, anti-inflammatory and anti-apoptotic properties. We investigated the effects of hydrogen on hepatic ischemia-reperfusion (I/R) and laparoscopic hepatectomy in swine. Methods Twenty-one healthy Bama miniature pigs were randomly divided into the sham group, ischemia-reperfusion injury (IRI) group, HRS-5 (5 mL/kg) group, and HRS-10 (10 mL/kg) group. HRS was injected through the portal vein 10 min before reperfusion and at postoperative day 1, 2 and 3. The roles of HRS on oxidative stress, inflammatory response and liver regeneration were studied. Results Compared with the IRI group, HRS treatment attenuated oxidative stress by increasing catalase activity and reducing myeloperoxidase. White blood cells in the HRS-10 group were reduced compared with the IRI group (P < 0.01). In the HRS-10 group, interleukin-1 beta, interleukin-6 and tumor necrosis factor alpha, C-reactive protein and cortisol were downregulated, whereas interleukin-10 was upregulated. In addition, HRS attenuated endothelial cell injury and promoted the secretion of angiogenic cytokines, including vascular endothelial growth factor, angiopoietin-1 and angiopoietin-2. HRS elevated the levels of hepatocyte growth factor, Cyclin D1, proliferating cell nuclear antigen, Ki-67 and reduced the secretion of transforming growth factor-beta. Conclusions HRS treatment may exert a protective effect against I/R and hepatectomy-induced hepatic damage by reducing oxidative stress, suppressing the inflammatory response and promoting liver regeneration.

Influence of Hydrogen-rich Saline on Hepatocyte Autophagy During Laparoscopic Liver Ischaemia-reperfusion Combined Resection Injury in Miniature Pigs

Introduction: The purpose of this study was to investigate the protective effect of hydrogen-rich saline (HRS) against liver ischaemia-reperfusion combined resection injury. Material and Methods: Eighteen miniature pigs were randomly divided into three groups: a sham operated group (sham group, laparoscopic liver ischaemia-reperfusion combined resection injury group (IRI group), and a hydrogen-rich saline intervention group (IRI + HRS group). Samples of hepatic tissue and serum were collected at the time of reperfusion and then 3 h, 1 d, and 3 d post reperfusion. Liver function, oxidative stress, autophagy-related mRNA genes, and protein expression were evaluated. Changes in cell and tissue ultrastructure were examined by transmission electron microscopy. Results: Compared with the sham group, the level of autophagy of hepatocytes increased in the IRI and IRI + HRS groups, corresponding to high oxidative stress and severe liver function injury. Liver function, antioxidant content, autophagy levels, and liver injury were improved after intervention with HRS in the IRI + HRS group compared with the IRI group. Conclusion: Intervention with hydrogen-rich saline could exert a protective effect against liver ischaemia-reperfusion combined resection injury through the reduction of oxidative stress and hepatocyte autophagy.