Protective Effects of Methane-Rich Saline on Renal Ischemic-Reperfusion Injury in a Mouse Model

Therapeutic effect of methane and its mechanism in disease treatment

Methane is the simplest hydrocarbon, consisting of one carbon atom and four hydrogen atoms. It is abundant in marsh gas, livestock rumination, and combustible ice. Little is known about the use of methane in human disease treatment. Current research indicates that methane is useful for treating several diseases including ischemia and reperfusion injury, and inflammatory diseases. The mechanisms underlying the protective effects of methane appear primarily to involve anti-oxidation, anti-inflammation, and anti-apoptosis. In this review, we describe the beneficial effects of methane on different diseases, summarize possible mechanisms by which methane may act in these conditions, and discuss the purpose of methane production in hypoxic conditions. Then we propose several promising directions for the future research.

Sialic acid-modified dexamethasone lipid calcium phosphate gel core nanoparticles for target treatment of kidney injury

Acute kidney injury (AKI) is a common clinical disease with high morbidity and mortality. Glucocorticoids are drugs that effectively relieve AKI, but the systemic side effects of long-term use limit their use. Herein, we constructed sialic acid-modified dexamethasone sodium phosphate (Dsp)-loaded lipid calcium phosphate gel core nanoparticles (SA-NPs) for the targeted treatment of ischemia-reperfusion (I/R)-induced AKI to improve efficacy and reduce side effects. The obtained nanoparticles could effectively encapsulate Dsp with 66.8% encapsulation efficiency and 4.56% (w/w) drug content. In vitro release indicates that the nanoparticles have a certain sustained release effect and have the characteristics of acid-sensitive release. And SA-NPs significantly increased the cellular uptake and kidney accumulation respectively through the combination of SA and E-selectin receptors overexpressed in inflamed vascular endothelial cells. Besides, the in vivo pharmacokinetic studies showed that Dsp-loaded SA-NPs significantly increased the residence time in the body and their plasma half-life was 1.7 times that of free Dsp. SA-NPs significantly improved the renal function, decreased the level of pro-inflammatory factors, and adjusted the oxidative stress factors and apoptotic proteins compared to free Dsp solution in pharmacodynamic studies. Moreover, little negative effects on blood glucose and bone mineral density were observed. Our study might provide a new strategy for the safe and effective targeting treatment of AKI or other related inflammatory diseases.

Methane Alleviates Inflammation and Apoptosis of Dextran Sulfate Sodium-Induced Inflammatory Bowel Diseases by Inhibiting Toll-Like Receptor 4 (TLR4)/Myeloid Differentiation Factor 88 (MyD88)/Nuclear Translocation of Nuclear Factor-κB (NF-κB) and Endoplasmic Reticulum Stress Pathways in Mice

Background

Inflammatory bowel diseases (IBDs) are chronic idiopathic diseases with increased occurrence and recurrence rates. The aim of this study was to explore whether methane-rich saline (MRS) would be beneficial to IBD.

Material/Methods

Dextran sulfate sodium (DSS) was utilized to establish an IBD model. Male C57BL/6J mice were randomly grouped as follows: the control group, the DSS+NS group, the DSS+5-ASA group, the DSS+MRS (1) and DSS+MRS (10) groups. Seven days after model induction, blood and colon tissues were collected to assess the treatment effects.

Results

The DSS+MRS (10) group showed obviously reduced weight loss, disease activity index, and spleen index. The isolated colon samples had a notably longer length, less thickness and weight, and better macroscopic score with MRS treatment compared with the DSS+NS group. Additionally, assessment of morphological impairment revealed a milder and lower microscopic score in the DSS+MRS (10) group, consistent with the myeloperoxidase (MPO) results. The inflammation-related molecules levels were dramatically reduced by MRS. MRS also significantly reduced oxidative stress related proteins. In addition, apoptotic cells were visually decreased in the DSS+MRS (10) group, in which the pro-apoptotic molecules Bax and cleaved caspase-3 were reduced, whereas the level of Bcl-2 was increased. Furthermore, MRS markedly decreased the TLR4, MyD88, p-NF-κB p65, p-IKKαβ, and p-IκBα, and increased IL-10, p-JAK1, and p-STAT3 expression levels. Proteins involved in endoplasmic reticulum stress (ERS) were also notably reduced under MRS treatment.

Conclusions

MRS exerts protective effects on DSS-induced IBD via inhibiting inflammatory reaction, promoting anti-inflammatory capacity, suppressing oxidative stress, and ameliorating apoptosis.

The role of methane in plant physiology: a review

Methane (CH₄), one of the most important greenhouse gases, has conventionally been considered as a physiologic inert gas. However, this perspective has been challenged by the observation that CH₄ has diverse biological functions in animals, such as anti-inflammatory, antioxidant, and anti-apoptosis. Meanwhile, it has now been identified as a possible candidate of gaseous signaling molecule in plants, although its biosynthetic and metabolic pathways as well as the mechanism(s) of CH₄ signaling have not fully understood yet. This paper aims to review the available evidence for the biological roles of CH₄ in regulating plant physiology. Although currently available reports do not fully support the notion of CH₄ as a gasotransmitter, they do show that CH₄ might be produced by an aerobic, non-microbial pathway from plants, and plays important roles in enhancing plant tolerance against abiotic stresses, such as salinity, drought, heavy metal exposure, and promoting root development, as well as delaying senescence and browning. Further results showed that CH₄ could interact with reactive oxygen species (ROS), other gaseous signaling molecules [e.g., nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S)], and glutathione (GSH). These reports thus support the idea that plant-produced CH₄ might be a component of a survival strategy of plants. Finally, the possibility of CH₄ application in agriculture is preliminarily discussed.

Methane and Inflammation - A Review (Fight Fire with Fire)

Mammalian methanogenesis is regarded as an indicator of carbohydrate fermentation by anaerobic gastrointestinal flora. Once generated by microbes or released by a non-bacterial process, methane is generally considered to be biologically inactive. However, recent studies have provided evidence for methane bioactivity in various in vivo settings. The administration of methane either in gas form or solutions has been shown to have anti-inflammatory and neuroprotective effects in an array of experimental conditions, such as ischemia/reperfusion, endotoxemia and sepsis. It has also been demonstrated that exogenous methane influences the key regulatory mechanisms and cellular signalling pathways involved in oxidative and nitrosative stress responses. This review offers an insight into the latest findings on the multi-faceted organ protective activity of exogenous methane treatments with special emphasis on its versatile effects demonstrated in sepsis models.

Methane-Rich Saline: A Potential Resuscitation Fluid for Hemorrhagic Shock

Hemorrhagic shock is caused by massive blood loss. If the patient is not fully resuscitated in time, this may eventually lead to multiple organ failure and even death. Previous studies on methane-rich saline in animal models showed that it confers resistance against many diseases. In this study, we explored the protective effect of methane-rich saline, used as a resuscitation fluid, in hemorrhagic shock. Hemorrhagic shock was induced in SD rats by bloodletting via intubation of the right femoral artery. The rats were divided into three groups: a sham control group (sham control), a shock group resuscitated by an infusion of autologous blood and an equivalent volume of normal saline (Shock+NS), and a shock group resuscitated by an infusion of autologous blood and an equivalent volume of methane-rich saline (Shock+MRS). Assessment of blood pressure and levels of plasma lactate showed that resuscitation using methane-rich saline (MRS) restored systemic blood pressure and reduced the levels of lactate in the plasma. Meanwhile, lower levels of serum IL-6 and TNF-α were also observed in the group resuscitated with MRS. In the heart, liver, and kidney, MRS reduced inflammation and oxidative stress levels. Analysis of organ function via levels of biochemical indicators revealed that the group resuscitated with MRS had reduced serum levels of AST and CK, indicating a potential cardioprotective effect. The expression levels of apoptosis-related proteins, including those of Bcl-2/Bax, and the results of TUNEL-labeling assay indicated that MRS significantly reduced apoptosis in the heart. Methane also had a positive effect on the expression of the PGC-1α/SIRT3/SOD2 signaling pathway. Our results showed that MRS can potentially serve as a novel resuscitation fluid because of its anti-inflammatory, antioxidative, and antiapoptotic properties.

Methane-Rich Saline Counteracts Cholestasis-Induced Liver Damage via Regulating the TLR4/NF-κB/NLRP3 Inflammasome Pathway

Cholestatic liver injury, due to obstruction of the biliary tract or genetic defects, is often accompanied by progressive inflammation and liver fibrosis. Methane-rich saline (MRS) has anti-inflammatory properties. However, whether MRS can provide protective effect in cholestatic liver injury is still unclear. In this study, Sprague-Dawley rats received bile duct ligation (BDL) to generate a cholestatic model followed by MRS treatment (10 mL/kg, ip treatment) every 12 h after the operation to explore the potential protective mechanism of MRS in cholestatic liver injury. We found that MRS effectively improved liver function, alleviated liver pathological damage, and localized infiltration of inflammatory cells. MRS treatment decreased the expression of hepatic fibrosis-associated proteins to alleviate liver fibrosis. Furthermore, MRS treatment suppressed the TLR4/NF-κB pathway and further reduced the levels of proinflammatory factors. Downregulation of NF-κB subsequently reduced the NLRP3 expression to inhibit pyroptosis. Our data indicated that methane treatment prevented cholestatic liver injury via anti-inflammatory properties that involved the TLR4/NF-κB/NLRP3 signaling pathway.

Protective Effect of Methane-Rich Saline on Acetic Acid-Induced Ulcerative Colitis via Blocking the TLR4/NF-κB/MAPK Pathway and Promoting IL-10/JAK1/STAT3-Mediated Anti-inflammatory Response

Ulcerative colitis (UC) is an inflammation-related disease involved in uncontrolled inflammation and oxidative stress and is characterized by high recurrence and relapse risk. As a rising star in gas medicine, methane owns the properties of anti-inflammation, antioxidation, and antiapoptosis. Based on the possible mechanism, we aimed to investigate the effect of methane on UC. Methane-rich saline (MRS) was introduced here, and UC was induced by acetic acid. All the C57BL/6 mice were allocated into groups as follows: control group, colitis model group, colitis treated with salazosulfapyridine (SASP) group, and colitis treated with MRS (1 or 10 ml/kg) groups. Tissue damage, the degree of inflammation, oxidative stress, and apoptosis were evaluated in the study, as well as the TLR4/NF-κB/MAPK and IL-10/JAK1/STAT3 signaling pathways for further exploration of the potential mechanism. The results showed that MRS (1) alleviated tissue damage caused by acetic acid, (2) controlled acetic acid-induced inflammation, (3) inhibited acetic acid-caused oxidative stress, (4) reduced colonic cell apoptosis due to acetic acid, (5) suppressed the TLR-4/NF-κB/MAPK signaling pathway, and (6) activated IL-10/JAK1/STAT3 anti-inflammatory response to improve the injury induced by acetic acid. We conclude that MRS has a protective effect on acetic acid-induced ulcerative colitis in mice via blocking the TLR4/NF-κB/MAPK signaling pathway and promoting the IL-10/JAK1/STAT3-mediated anti-inflammatory response.