Luminal preloading with hydrogen-rich saline ameliorates ischemia-reperfusion injury following intestinal transplantation in rats

Si-based agent alleviated small bowel ischemia-reperfusion injury through antioxidant effects

The progression of small bowel ischemia-reperfusion (IR) injury causes cells in the intestinal tract to undergo necrosis, necessitating surgical resection, which may result in loss of intestinal function. Therefore, developing therapeutic agents that can prevent IR injury at early stages and suppress its progression is imperative. As IR injury may be closely related to oxidative stress, antioxidants can be effective therapeutic agents. Our silicon (Si)-based agent, an antioxidant, generated a large amount of hydrogen in the intestinal tract for a prolonged period after oral administration. As it has been effective for ulcerative colitis, renal failure, and IR injury during skin flap transplantation, it could be effective for small intestinal IR injury. Herein, we investigated the efficacy of an Si-based agent in a mouse model of small intestinal IR injury. The Si-based agent suppressed the apoptosis of small intestinal epithelial cells by reducing the oxidative stress induced by IR injury. In addition, the thickness of the mucosal layer in the small intestine of the Si-based agent-administered group was significantly higher than that in the untreated group, revealing that Si-based agent is effective against small intestinal IR injuries. In the future, Si-based agents may improve the success rate of small intestine transplantation.

Hydrogen in Transplantation: Potential Applications and Therapeutic Implications

Hydrogen gas, renowned for its antioxidant properties, has emerged as a novel therapeutic agent with applications across various medical domains, positioning it as a potential adjunct therapy in transplantation. Beyond its antioxidative properties, hydrogen also exerts anti-inflammatory effects by modulating pro-inflammatory cytokines and signaling pathways. Furthermore, hydrogen's capacity to activate cytoprotective pathways bolsters cellular resilience against stressors. In recent decades, significant advancements have been made in the critical medical procedure of transplantation. However, persistent challenges such as ischemia-reperfusion injury (IRI) and graft rejection continue to hinder transplant success rates. This comprehensive review explores the potential applications and therapeutic implications of hydrogen in transplantation, shedding light on its role in mitigating IRI, improving graft survival, and modulating immune responses. Through a meticulous analysis encompassing both preclinical and clinical studies, we aim to provide valuable insights into the promising utility of hydrogen as a complementary therapy in transplantation.

Progress in preservation of intestinal grafts by oxygenated hypothermic machine perfusion

Intestine transplantation (IT) is a critical treatment strategy for irreversible intestinal failure. Among all abdominal solid organ transplants, the intestine was the most vulnerable to ischemia and reperfusion injury (IRI). The static cold storage (SCS) technique is currently the most commonly used graft preservation method, but its hypoxia condition causes metabolic disorders, resulting in the occurrence of IRI, limiting its application in marginal organs. It is especially important to improve preservation techniques in order to minimize damage to marginal donor organs, which draws more attention to machine perfusion (MP). There has been much debate about whether it is necessary to increase oxygen in these conditions to support low levels of metabolism since the use of machine perfusion to preserve organs. There is evidence that oxygenation helps to restore intracellular ATP levels in the intestine after thermal or cold ischemia damage. The goal of this review is to provide an overview of the role of oxygen in maintaining environmental stability in the gut under hypoxic conditions, as well as to investigate the possibilities and mechanisms of oxygen delivery during preservation in intestine transplantation studies and clinical models.

Attenuation of pulmonary damage in aged lipopolysaccharide-induced inflammation mice through continuous 2 % hydrogen gas inhalation: A potential therapeutic strategy for geriatric inflammation and survival

INTRODUCTION

With the global population aging, there is an increased prevalence of sepsis among the elderly, a demographic particularly susceptible to inflammation. This study aimed to evaluate the therapeutic potential of hydrogen gas, known for its anti-inflammatory and antioxidant properties, in attenuating inflammation specifically in the lungs and liver, and age-associated molecular markers in aged mice.

METHODS

Male mice aged 21 to 23 months, representative of the human elderly population, were subjected to inflammation via intraperitoneal injection of lipopolysaccharide (LPS). The mice were allocated into eight groups to examine the effects of varying durations and concentrations of hydrogen gas inhalation: control, saline without hydrogen, saline with 24-hour 2 % hydrogen, LPS without hydrogen, LPS with 24-hour 2 % hydrogen, LPS with 6-hour 2 % hydrogen, LPS with 1-hour 2 % hydrogen, and LPS with 24-hour 1 % hydrogen. Parameters assessed included survival rate, activity level, inflammatory biomarkers, and organ injury.

RESULTS

Extended administration of hydrogen gas specifically at a 2 % concentration for 24 h led to a favorable prognosis in the aged mice by reducing mRNA expression of inflammatory biomarkers in lung and liver tissue, mitigating lung injury, and diminishing the expression of the senescence-associated protein p21. Moreover, hydrogen gas inhalation selectively ameliorated senescence-related markers in lung tissue, including C-X-C motif chemokine 2, metalloproteinase-3, and arginase-1. Notably, hydrogen gas did not alleviate LPS-induced liver injury under the conditions tested.

CONCLUSION

The study highlights that continuous inhalation of hydrogen gas at a 2 % concentration for 24 h can be a potent intervention in the geriatric population for improving survival and physical activity by mitigating pulmonary inflammation and modulating senescence-related markers in aged mice with LPS-induced inflammation. This finding paves the way for future research into hydrogen gas as a therapeutic strategy to alleviate severe inflammation that can lead to organ damage in the elderly.

Hydrogen inhalation attenuates lung contusion after blunt chest trauma in mice

BACKGROUND

Lung contusion caused by blunt chest trauma evokes a severe inflammatory reaction in the pulmonary parenchyma that may be associated with acute respiratory distress syndrome. Although hydrogen gas has antioxidant and anti-inflammatory effects and is protective against multiple types of lung injury at safe concentrations, the effects of inhaled hydrogen gas on blunt lung injury have not been previously investigated. Therefore, using a mouse model, we tested the hypothesis that hydrogen inhalation after chest trauma would reduce pulmonary inflammation and acute lung injury associated with lung contusion.

METHODS

Inbred male C57BL/6 mice were randomly divided into 3 groups: sham with air inhalation, lung contusion with air inhalation, and lung contusion with 1.3% hydrogen inhalation. Experimental lung contusion was induced using a highly reproducible and standardized apparatus. Immediately after induction of lung contusion, mice were placed in a chamber exposed to 1.3% hydrogen gas in the air. Histopathological analysis and real-time polymerase chain reaction in lung tissue and blood gas analysis were performed 6 hours after contusion.

RESULTS

Histopathological examination of the lung tissue after contusion revealed perivascular/intra-alveolar hemorrhage, perivascular/interstitial leukocyte infiltration, and interstitial/intra-alveolar edema. These histological changes and the extent of lung contusion, as determined by computed tomography, were significantly mitigated by hydrogen inhalation. Hydrogen inhalation also significantly reduced inflammatory cytokine and chemokine mRNA levels and improved oxygenation.

CONCLUSION

Hydrogen inhalation therapy significantly mitigated inflammatory responses associated with lung contusion in mice. Hydrogen inhalation therapy may be a supplemental therapeutic strategy for treating lung contusion.

Luminal administration of biliverdin ameliorates ischemia-reperfusion injury following intestinal transplant in rats

BACKGROUND

Intestinal grafts are susceptible to ischemia-reperfusion injury, resulting in the loss of mucosal barrier function and graft failure. Biliverdin is known to exert a variety of cytoprotective functions against oxidative tissue injury. Because the mucosal layer is the primary site of ischemia-reperfusion injury, mucosa-targeting strategies by luminal delivery of reagents might be beneficial. We tested whether intraluminal administration of biliverdin as an adjuvant to standard preservation solutions protected against ischemia-reperfusion injury.

METHODS

Orthotopic syngeneic intestinal transplants were performed on Lewis rats after 6 hours of cold preservation. Saline containing biliverdin (10 μM) or without biliverdin was introduced into the lumen of the intestinal grafts immediately before cold preservation.

RESULTS

Damage to the intestinal mucosa caused by ischemia-reperfusion injury resulted in severe morphological changes, including blunting of the villi and erosion, and led to significant loss of gut barrier function 3 hours after reperfusion. These changes to the mucosa were notably ameliorated by intraluminal administration of biliverdin. Biliverdin also effectively inhibited upregulation of messenger RNAs for interleukin-6, inducible nitric oxide synthase, and C-C motif chemokine 2. Additionally, biliverdin treatment prevented the loss of expression of claudin-1, a transmembrane, tight-junction barrier protein. The 14-day survival of recipients of biliverdin-treated grafts was significantly improved as compared with the recipients of saline-treated control grafts (83.3% vs 38.9%, P = .030).

CONCLUSION

This study demonstrated that luminally delivered biliverdin provides beneficial effects during the transplant of rat small intestinal grafts and could be an attractive therapeutic option in organ transplantation.

Luminal Administration of a Water-soluble Carbon Monoxide-releasing Molecule (CORM-3) Mitigates Ischemia/Reperfusion Injury in Rats Following Intestinal Transplantation

BACKGROUND

The protective effects of carbon monoxide (CO) against ischemia/reperfusion (IR) injury during organ transplantation have been extensively investigated. Likewise, CO-releasing molecules (CORMs) are known to exert a variety of pharmacological activities via liberation of controlled amounts of CO in organs. Therefore, we hypothesized that intraluminal administration of water-soluble CORM-3 during cold storage of intestinal grafts would provide protective effects against IR injury.

METHODS

Orthotopic syngeneic intestinal transplantation was performed in Lewis rats following 6 h of cold preservation in Ringer solution or University of Wisconsin solution. Saline containing CORM-3 (100 µmol/L) or its inactive counterpart (iCORM-3) was intraluminally introduced in the intestinal graft before cold preservation.

RESULTS

Histopathological analysis of untreated and iCORM-3-treated grafts revealed a similar erosion and blunting of the intestinal villi. These changes in the mucosa structure were significantly attenuated by intraluminal administration of CORM-3. Intestinal mucosa damage caused by IR injury led to considerable deterioration of gut barrier function 3 h postreperfusion. CORM-3 significantly inhibited upregulation of proinflammatory mRNA levels, ameliorated intestinal morphological changes, and improved graft blood flow and mucosal barrier function. Additionally, CORM-3-treated grafts increased recipient survival rates. Pharmacological blockade of soluble guanylyl cyclase activity significantly reversed the protective effects conferred by CORM-3, indicating that CO partially mediates its therapeutic actions via soluble guanylyl cyclase activation.

CONCLUSIONS

Our study demonstrates that luminally delivered CORM-3 provides beneficial effects in cold-stored rat small intestinal grafts and could be an attractive therapeutic application of CO in the clinical setting of organ preservation and transplantation.

Protective Effects of Hydrogen-Rich Saline on Experimental Intestinal Volvulus in Rats

BACKGROUND

Intestinal volvulus can cause morbidity and mortality. Surgical reduction, on the other hand, could result in ischemia-reperfusion (I/R) injury. Hydrogen rich saline solution (HRSS neutralizes free radicals in the body. This study aimed to investigate the effects of HRSS in I/R injury in experimental intestinal volvulus in rats.

METHODS

Thirty rats were randomly allocated into 5 groups. All procedures were done under general anesthesia and sterile conditions in each animal. Five ml/kg of saline and HRSS were administered intraperitoneally (ip) in Sham (Group 1) and HRSS (Group 2) groups, respectively. Groups 3, 4, and 5 constituted the study groups in which volvulus was created in a 5-cm- long ileal segment 2 cm proximal to the ileocecal valve. After 2 hours the volvuli were reduced and following 2 hours of reperfusion, these segments were removed. In volvulus-I/R group (Group 3) no additional procedure was done. HRSS was administered shortly before reperfusion (reduction of the volvulus) in Treatment I (Group 4) and 1 h before experimental volvulus in Treatment II (Group 5) groups. Blood and intestinal tissue samples were obtained from all rats at the 4th hour. Both tissue and blood total oxidant (TOS) and antioxidant status (TAS) levels were determined and tissue histomorphologies were studied. Oxidative stress indices (TOS ÷ TAS) (OSI) were calculated.

RESULTS

Tissue TOS and OSI levels and histomorphological injury scores were statistically lower in treatment groups than I/R group, whereas blood TOS and OSI levels were similar between the groups.

CONCLUSIONS

This study provides biochemical and histomorphological evidence that HRSS prevents intestinal damage in I/R injury caused by volvulus.

Hydrogen Attenuated Inflammation Response and Oxidative in Hypoxic Ischemic Encephalopathy via Nrf2 Mediated the Inhibition of NLRP3 and NF-κB

Hypoxia and ischemia cause neonatal encephalopathy and brain injury and can further result in cerebral palsy, cognitive impairment, growth restriction, and epilepsy. Induction of neuroprotection is a crucial therapeutic strategy for the treatment of perinatal hypoxic-ischaemic encephalopathy (HIE). Hydrogen has neuroprotective effects against brain-related diseases. Inflammation and oxidative stress are the two main pathophysiological mechanisms in neonatal hypoxic-ischaemic injury. Nuclear factor erythroid 2-related factor 2 (Nrf2) is an endogenous redox-sensitive transcription factor that participates in the antioxidant defence system through its effects on inflammation and oxidative stress. Herein, the research focuses on the mechanisms by which Nrf2 participates in the protection of hydrogen against HIE. The model of HIE was established by ligation of the right carotid artery and hypoxia in wild-type (WT) and Nrf2-/- mice. First, Nrf2 pathway activity was detected after hypoxia-ischaemia (HI) followed or not by hydrogen treatment. Brain injury, apoptosis, the inflammatory response, oxidative stress injury, and learning and memory function were assayed. We found that HI induced Nrf2 expression and signalling activation. Hydrogen alleviated the infarction volume, brain water content, neurological scores, apoptosis and long-term learning and memory functions after HI in WT mice but not in Nrf2-/- mice. Moreover, the oxidative products reactive oxygen species (ROS) and malondialdehyde (MDA) and the cytokines tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6) and High mobility group box 1 (HMGB1) were reduced and the antioxidant enzymes Superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) were upregulated by hydrogen treatment after HI in WT mice, but not in Nrf2-/- mice. In addition, the absence of Nrf2 abolished the suppressive effect of hydrogen on the expression of Nacht, Lrr, and Pyd domains-containing protein 3 (NLRP3) pathway members and p65 NF-κB after HI. Taken together, our findings showed that hydrogen alleviated cellular injury and apoptosis, neurobehavioural deficits, the inflammatory response and oxidative stress via the Nrf2-mediated NLRP3 and NF-κB pathways.

Hydrogen: Potential Applications in Solid Organ Transplantation

Ischemia reperfusion injury (IRI) in organ transplantation has always been an important hotspot in organ protection. Hydrogen, as an antioxidant, has been shown to have anti-inflammatory, antioxidant, and antiapoptotic effects. In this paper, the protective effect of hydrogen against IRI in organ transplantation has been reviewed to provide clues for future clinical studies.