Hayato Yamashita

Gut microbiota and host metabolism in liver cirrhosis

The gut microbiota has the capacity to produce a diverse range of compounds that play a major role in regulating the activity of distal organs and the liver is strategically positioned downstream of the gut. Gut microbiota linked compounds such as short chain fatty acids, bile acids, choline metabolites, indole derivatives, vitamins, polyamines, lipids, neurotransmitters and neuroactive compounds, and hypothalamic-pituitary-adrenal axis hormones have many biological functions. This review focuses on the gut microbiota and host metabolism in liver cirrhosis. Dysbiosis in liver cirrhosis causes serious complications, such as bacteremia and hepatic encephalopathy, accompanied by small intestinal bacterial overgrowth and increased intestinal permeability. Gut dysbiosis in cirrhosis and intervention with probiotics and synbiotics in a clinical setting is reviewed and evaluated. Recent studies have revealed the relationship between gut microbiota and host metabolism in chronic metabolic liver disease, especially, non-alcoholic fatty liver disease, alcoholic liver disease, and with the gut microbiota metabolic interactions in dysbiosis related metabolic diseases such as diabetes and obesity. Recently, our understanding of the relationship between the gut and liver and how this regulates systemic metabolic changes in liver cirrhosis has increased. The serum lipid levels of phospholipids, free fatty acids, polyunsaturated fatty acids, especially, eicosapentaenoic acid, arachidonic acid, and docosahexaenoic acid have significant correlations with specific fecal flora in liver cirrhosis. Many clinical and experimental reports support the relationship between fatty acid metabolism and gut-microbiota. Various blood metabolome such as cytokines, amino acids, and vitamins are correlated with gut microbiota in probiotics-treated liver cirrhosis patients. The future evaluation of the gut-microbiota-liver metabolic network and the intervention of these relationships using probiotics, synbiotics, and prebiotics, with sufficient nutrition could aid the development of treatments and prevention for liver cirrhosis patients.

Hydrogen inhalation protects against acute lung injury induced by hemorrhagic shock and resuscitation

INTRODUCTIONnHemorrhagic shock followed by fluid resuscitation (HS/R) triggers an inflammatory response and causes pulmonary inflammation that can lead to acute lung injury (ALI). Hydrogen, a therapeutic gas, has potent cytoprotective, antiinflammatory, and antioxidant effects. This study examined the effects of inhaled hydrogen on ALI caused by HS/R.nnnMETHODSnRats were subjected to hemorrhagic shock by withdrawing blood to lower blood pressure followed by resuscitation with shed blood and saline to restore blood pressure. After HS/R, the rats were maintained in a control gas of similar composition to room air or exposed to 1.3% hydrogen.nnnRESULTSnHS/R induced ALI, as demonstrated by significantly impaired gas exchange, congestion, edema, cellular infiltration, and hemorrhage in the lungs. Hydrogen inhalation mitigated lung injury after HS/R, as indicated by significantly improved gas exchange and reduced cellular infiltration and hemorrhage. Hydrogen inhalation did not affect hemodynamic status during HS/R. Exposure to 1.3% hydrogen significantly attenuated the upregulation of the messenger RNAs for several proinflammatory mediators induced by HS/R. Lipid peroxidation was reduced significantly in the presence of hydrogen, indicating antioxidant effects.nnnCONCLUSIONnHydrogen, administered through inhalation, may exert potent therapeutic effects against ALI induced by HS/R and attenuate the activation of inflammatory cascades.

Eluted substances from hemodialysis membranes elicit positive skin prick tests in bioincompatible patients.

Recently, hypotension and malaise during hemodialysis using polysulfone (PS) membranes have been reported. This study aimed to evaluate the bioincompatibility of eluted substances from PS hemodialysis membranes that can induce hypotension, malaise, and anaphylactic shock. Polyvinylpyrrolidone (PVP) elution from five hemodialysis membranes was measured in an in vitro experimental circulation. Skin prick tests (SPTs) with PVP or the priming fluid of hemodialysis membranes were carried out for seven PS membrane-incompatible patients and seven healthy volunteers. Skin reactivity for histamine was compared in patients and healthy volunteers. The symptoms of PS membrane-incompatible cases were hypotension, dyspnea, nausea, or vomiting. One patient had gone into shock. PVP was eluted from hemodialysis membranes, but the SPT for PVP was negative in all patients. SPTs with priming fluid (or priming fluid effluxed during priming) were positive in four out of six patients. However, the SPT with bisphenol A was positive in one patient. The area of the flare reaction against histamine in patients was smaller than that of healthy subjects. In conclusion, eluted substances apart from PVP from hemodialysis membranes could cause bioincompatibility with PS membranes.

Intraperitoneally administered, hydrogen-rich physiologic solution protects against postoperative ileus and is associated with reduced nitric oxide production

BACKGROUNDnPostoperative ileus, a transient impairment of bowel motility initiated by intestinal inflammation, is common after an abdominal operation and leads to increased hospital stays and costs. Hydrogen has potent anti-inflammatory and antioxidant properties and potential therapeutic value. Solubilized hydrogen may be a portable and practical means of administering therapeutic hydrogen gas. We hypothesized that intraperitoneal administration of hydrogen-rich saline would ameliorate postoperative ileus.nnnMETHODSnIleus was induced via surgical manipulation in mice and rats. The peritoneal cavity was filled with 1.0xa0mL saline or hydrogen-rich saline (≥1.5-2.0xa0ppm) before closure of the abdominal incision. Intestinal transit was assessed 24xa0hours postoperatively. Inflammation was examined by quantitation of neutrophil extravasation and expression of proinflammatory markers. Nitric oxide production was assessed in cultured muscularis propria.nnnRESULTSnSurgical manipulation resulted in a marked delay in intestinal transit and was associated with upregulation of proinflammatory cytokines and increased neutrophil extravasation. Bowel dysmotility, induced by surgical manipulation and inflammatory events, was significantly attenuated by intra-abdominal administration of hydrogen-rich saline. Nitric oxide production in the muscle layers of the bowel was inhibited by hydrogen treatment.nnnCONCLUSIONnA single intraperitoneal dose of hydrogen-rich saline ameliorates postoperative ileus by inhibiting the inflammatory response and suppressing nitric oxide production.

Endogenous Interleukin-18 Regulates Testicular Germ Cell Apoptosis during Endotoxemia

Orchitis (testicular swelling) often occurs during systemic inflammatory conditions, such as sepsis. Interleukin 18 (IL18) is a proinflammatory cytokine and is an apoptotic mediator during endotoxemia, but the role of IL18 in response to inflammation in the testes was unclear. WT and IL18 knockout (KO) mice were injected lipopolysaccharide (LPS) to induce endotoxemia and examined 12 and 48u200a h after LPS administration to model the acute and recovery phases of endotoxemia. Caspase activation was assessed using immunohistochemistry. Protein and mRNA expression were examined by western blot and quantitative real-time RT-PCR respectively. During the acute phase of endotoxemia, apoptosis (as indicated by caspase-3 cleavage) was increased in WT mice but not in IL18 KO mice. The death receptor-mediated and mitochondrial-mediated apoptotic pathways were both activated in the WT mice but not in the KO mice. During the recovery phase of endotoxemia, apoptosis was observed in the IL18 KO mice but not in the WT mice. Activation of the death-receptor mediated apoptotic pathway could be seen in the IL18 KO mice but not the WT mice. These results suggested that endogenous IL18 induces germ cell apoptosis via death receptor mediated- and mitochondrial-mediated pathways during the acute phase of endotoxemia and suppresses germ cell apoptosis via death-receptor mediated pathways during recovery from endotoxemia. Taken together, IL18 could be a new therapeutic target to prevent orchitis during endotoxemia.

Supplementation of parenteral nutrition with fish oil attenuates acute lung injury in a rat model

Fish oil rich in n-3 polyunsaturated fatty acids has diverse immunomodulatory properties and attenuates acute lung injury when administered in enternal nutrition. However, enteral nutrition is not always feasible. Therefore, we investigated the ability of parenteral nutrition supplemented with fish oil to ameliorate acute lung injury. Rats were infused with parenteral nutrition solutions (without lipids, with soybean oil, or with soybean oil and fish oil) for three days. Lipopolysaccharide (15 mg/kg) was then administered intratracheally to induce acute lung injury, characterized by impaired lung function, polymorphonuclear leukocyte recruitment, parenchymal tissue damage, and upregulation of mRNAs for inflammatory mediators. Administration of parenteral nutrition supplemented with fish oil prior to lung insult improved gas exchange and inhibited neutrophil recruitment and upregulation of mRNAs for inflammatory mediators. Parenteral nutrition supplemented with fish oil also prolonged survival. To investigate the underlying mechanisms, leukotriene B4 and leukotriene B5 secretion was measured in neutrophils from the peritoneal cavity. The neutrophils from rats treated with fish oil-rich parenteral nutrition released significantly more leukotriene B5, an anti-inflammatory eicosanoid, than neutrophils isolated from rats given standard parenteral nutrition. Parenteral nutrition with fish oil significantly reduced lipopolysaccharide-induced lung injury in rats in part by promoting the synthesis of anti-inflammatory eicosanoids.

Interleukin-18 Reduces Blood Glucose and Modulates Plasma Corticosterone in a Septic Mouse Model.

Background: Dysregulation of glucose metabolism, including hyperglycemia with insulin resistance, is commonly observed in critically ill patients. Interleukin-18 (IL-18) improves the insulin resistance associated with obesity, but the relationship between IL-18 and glucose metabolism in sepsis was unclear. The purpose of this study was to investigate the influence of IL-18 on hyperglycemia during sepsis. Methods: Sepsis was induced using cecal ligation and puncture (CLP) in wild-type (WT) mice, IL-18 knockout (KO) mice, and IL-18 KO mice pretreated with recombinant IL-18. Blood glucose and plasma insulin, glucagon, and corticosterone were measured. The mRNAs for gluconeogenic enzymes (g6pc, pck1) and activation of insulin signaling were also analyzed. Results: In both WT and IL-18 KO mice, CLP operation led to hyperglycemia that lasted longer (18u200ah) than after sham operation (6u200ah). Blood glucose levels in IL-18 KO mice were significantly higher than in WT mice, without alteration of insulin or glucagon levels. In IL-18 KO mice, insulin signaling in the liver and skeletal muscle was decreased during hyperglycemia as compared with WT mice without suppression of hepatic glucose production enzymes. Pretreatment with recombinant IL-18 reduced blood glucose levels after CLP. Additionally, corticosterone levels were higher after CLP in the presence of either endogenous or exogenous IL-18. Conclusion: IL-18 may reduce blood glucose by modulating insulin signaling in the liver during sepsis-induced hyperglycemia. IL-18 is an important factor associated with alterations in blood glucose during sepsis.

Antithrombin III improved neutrophil extracellular traps in lung after the onset of endotoxemia

BACKGROUNDnCoagulation and inflammation are closely linked during acute inflammatory conditions, such as sepsis. Antithrombin (AT) is an anticoagulant that also has anti-inflammatory activities. The effects of therapeutically administering AT III after the onset of endotoxemia or sepsis were not clear. Here, we studied the effects of administering AT III after inducing lethal endotoxemia in mice.nnnMETHODSnMice were injected intraperitoneally with lipopolysaccharide (LPS) to induce endotoxemia. AT III was administered 3xa0h later. We assessed survival and the severity of endotoxemia and quantified plasma cytokine levels and biochemical markers of liver and kidney function. In the lungs, we examined neutrophil accumulation, neutrophil extracellular traps, alveolar wall thickness, and chemokine (C-X-C motif) ligand 1 (cxcl-1), cxcl-2, and high mobility group box 1 expression.nnnRESULTSnAdministering AT III reduced the severity and mortality of LPS-induced endotoxemia as indicated by 24-h survival of 84% of the mice that received LPSxa0+xa0AT III and only 53% of mice given LPS alone (Pxa0<xa00.05). AT III treatment attenuated several changes induced in the lungs by endotoxemia including cxcl-2 mRNA expression, high mobility group box 1 protein expression, neutrophil accumulation, alveolar septal thickening, and neutrophil extracellular trap formation. AT III did not decrease plasma cytokine levels or plasma urea nitrogen levels that were upregulated as a result of LPS-induced endotoxemia.nnnCONCLUSIONSnAdministration of AT III after the onset of endotoxemia improved outcomes in a mouse model. The attenuation of lung inflammation may have a large impact on mortality and morbidity. Because lung inflammation increases the likelihood of mortality from sepsis, AT III could be a useful agent in septic patients.

Donor pretreatment with carbon monoxide prevents ischemia/reperfusion injury following heart transplantation in rats

Because inhaled carbon monoxide (CO) provides potent anti-inflammatory and antioxidant effects against ischemia reperfusion injury, we hypothesized that treatment of organ donors with inhaled CO would decrease graft injury after heart transplantation. Hearts were heterotopically transplanted into syngeneic Lewis rats after 8 hours of cold preservation in University of Wisconsin solution. Donor rats were exposed to CO at a concentration of 250 parts per million for 24 hours via a gas-exposure chamber. Severity of myocardial injury was determined by total serum creatine phosphokinase and troponin I levels at three hours after reperfusion. In addition, Affymetrix gene array analysis of mRNA transcripts was performed on the heart graft tissue prior to implantation. Recipients of grafts from CO-exposed donors had lower levels of serum troponin I and creatine phosphokinase; less upregulation of mRNA for interleukin-6, intercellular adhesion molecule-1, and tumor necrosis factor-α; and fewer infiltrating cells. Although donor pretreatment with CO altered the expression of 49 genes expressly represented on the array, we could not obtain meaningful data to explain the mechanisms by which CO potentiated the protective effects.Pretreatment with CO gas before organ procurement effectively protected cardiac grafts from ischemia reperfusion-induced injury in a rat heterotopic cardiac transplant model. A clinical report review indicated that CO-poisoned organ donors may be comparable to non-poisoned donors.

Endogenous Interleukin 18 Suppresses Hyperglycemia and Hyperinsulinemia during the Acute Phase of Endotoxemia in Mice

BACKGROUNDnHyperglycemia associated with insulin resistance is common among critically ill patients. Interleukin (IL)-18 has been linked with hyperglycemia and insulin resistance in chronic disease, but the relation between IL-18 and insulin resistance during critical illness was unexplored. This study investigated whether IL-18 modulates hyperglycemia and insulin resistance during acute inflammation.nnnMETHODSnWe injected lipopolysaccharide (LPS) 40u2009mg/kg into wild-type (WT) and IL-18 knockout (KO) mice to induce endotoxemia and examined insulin resistance and insulin-dependent signaling pathways during the acute phase.nnnRESULTSnDuring the first hour after LPS treatment, IL-18 KO mice showed higher blood glucose and insulin and less insulin receptor substrate-1 and less phosphorylated Akt in the liver compared with WT mice. Interleukin-18 KO mice exhibited better survival after LPS treatment.nnnCONCLUSIONSnThe findings suggest that endogenous IL-18 may attenuate hyperglycemia and modulate insulin signaling in liver. Accordingly, IL-18 may modulate glucose tolerance during acute inflammation.