Glycine maintains mitochondrial activity and bile composition following warm liver ischemia-reperfusion injury

Background and Aim: Experimental studies have shown protective effect by the non‐essential amino acid glycine to liver ischemia‐reperfusion (I/R) injury but the mechanism of action is unknown. Methods: A rabbit model of hepatic lobar I/R was used. Three groups of animals (n = 6) were studied: Sham group (laparotomy alone), ischemia reperfusion (I/R) group (1 h of liver lobar ischemia and 6 h of reperfusion), and a glycine I/R group (intravenous glycine 5 mg/kg prior to the I/R protocol). Systemic and hepatic hemodynamics, degree of liver injury (bile flow, transaminases), hepatic microcirculation, mitochondrial activity (redox state of cytochrome oxidase), bile composition and cytokines (tumor necrosis factor‐α and interleukin‐8) were measured during the experiment. Results: Glycine administration increased portal blood flow, bile production, hepatic microcirculation and maintained cytochrome oxidase activity as compared with the I/R group during reperfusion. Glycine also reduced bile lactate surge and stimulated acetoacetate release in bile during reperfusion versus the I/R group. Cytokine levels (tumor necrosis factor‐α, interleukin‐8) and hepatocellular injury (aspartate aminotransferase and alanine aminotransferase) were significantly reduced by glycine administration. Conclusion: Intravenous glycine administration reduces liver warm I/R injury by reducing the systemic inflammatory response, and maintaining cellular energy production.     

Effect of cold-ischemia time on nuclear factor-κB activation and inflammatory response in graft after orthotopic liver transplantation in rats

AIM: To study the mechanism and effect of nuclear factor-κB (NF-κB) activation and inflammatory response on the extended cold-preserved graft injury after orthotopic liver transplantation (OLT). METHODS: OLT was performed in rats with varying time of cold ischemia grafts (6, 18 and 24 h in University Wisconsin solution at 4 ℃). We determined the time of NF-κB activation and expression of tumor necrosis factor-α (TNF-α), cytokineinducible neutrophil chemoattractant (CINC), and intercellular adhesion molecule-1 (ICAM-1) within 6 h after reperfusion. Serum alarming aminotransferase (ALT), neutrophil sequestration, circulating neutrophil CD11b and L- selectin expression were also evaluated. RESULTS: The accumulation of neutrophils in the graft was significantly increased in the 18 h and 24 h cold-ischemia groups within 0.5 h after reperfusion, compared with the 6 h group. But the strongly activated neutrophils was slightly increased at 2 h after reperfusion and remained at high levels 4 h after reperfusion, which was synchronized with the common situation of recipients after transplantation. Prolonged cold-preservation did not affect neutrophil accumulation and activation. NF-κB activation preceded the expression of TNF-α, CINC, and ICAM-1 in the liver, which was significantly increased with prolonged cold preservation. In prolonged cold preserved grafts, prominently elevated NF-κB activation occurred at 0.5 h and 1 h, compared with that at 2 h after reperfusion, which was consistent with greatly increased intrahepatic TNF-α response. CONCLUSION: NF-κB activation is correlated with the expression of TNF-α, CINC, and ICAM-1 in vivo in OLT rats. Extended cold preservation of grafts might up-regulate TNF-α, CINC, and ICAM-1 expression in the grafts, most probably through elevated NF-κB activation, and might contribute to neutrophil infiltration in the grafts after reperfusion. Elevated NF-κB activity is harmful to inflammatory response in the grafts, and inhibited NF-κB activity might protect against early graft injury after liver transplantation.     

Suppression of tumor necrosis factor-alpha production and neutrophil infiltration during ischemia-reperfusion injury of the liver after heat shock preconditioning.

BACKGROUND/AIMS: Heat shock preconditioning provides the liver with ischemic tolerance. In this study we examined the effects of heat shock preconditioning on hepatic nonparenchymal cells in light of tumor necrosis factor-alpha (TNF-alpha) production and neutrophil infiltration. METHODS: Rats were exposed to heat shock pretreatment at 42 degrees C in the heat shock group (group HS) and at 37 degrees C in the control group (group C). After a 48-h recovery, the left hepatic lobes were given a 90-min ischemia and reperfused. Plasma concentrations of TNF-alpha, cytokine-induced neutrophil chemoattractant (CINC) and alanine aminotransferase (ALT) were measured. Liver tissues were checked for the presence of TNF-alpha mRNA. Histological staining for CINC and polymorphonuclear leukocyte (PMN) was also evaluated. RESULTS: In group HS, plasma TNF-alpha levels were significantly more suppressed than in group C (P<0.0001). Expressions of TNF-alpha mRNA in the liver was suppressed in group HS. Production of CINC 2 h after reperfusion was reduced in group HS (P<0.05). PMN infiltration was significantly reduced in group HS (P<0.01). In group HS, liver histology revealed less cellular damage and the plasma level of ALT was significantly reduced (P<0.0001). CONCLUSIONS: Heat shock preconditioning suppressed the production of TNF-alpha and CINC in the liver during reperfusion and consequently reduced neutrophil infiltration.     

Anticoagulant pretreatment attenuates production of cytokine-induced neutrophil chemoattractant following ischemia-reperfusion of rat liver

We investigated whether anticoagulation would diminish ischemia-reperfusion injury of the liver. Liver ischemia was induced in rats by occluding the portal vein for 30 min. Anticoagulant was injected intravenously 10 min before occlusion. Serum concentrations of cytokine-induced neutrophil chemoattractant (CINC) in untreated rats increased following reperfusion, reaching a peak at 6 hr, then decreasing gradually to control levels by 24 hr. CINC levels in rats pretreated with heparin (50 units/kg), AT-III (250 units/kg), or DEGR-Xa (10 mg/kg) peaked at 3 hr after reperfusion and declined to baseline within 12 hr; peak CINC values were significantly lower than in untreated control rats. Expression of CINC mRNA in liver tissue paralleled the CINC serum levels. Both myeloperoxidase activity and the number of neutrophils in the liver were decreased in the anticoagulant groups. In addition, significant correlations were observed between the maximum values of AST, ALT, and LDH versus the peak CINC levels following ischemia-reperfusion. These results indicate that the release of CINC after ischemia-reperfusion of the liver is mediated by activation of coagulation within the hepatic microcirculation.     

Erratum

Liver resections are frequently associated with significant ischemia-reperfusion (I-R) injury of the liver remnant. The aim of this study was to investigate whether deferoxamine (DFO) can ameliorate I-R injury during major hepatectomies performed under vascular exclusion of the liver in a porcine model. Twelve female domestic pigs were divided into control (n = 6) and DFO treatment (n = 6) groups and subjected to 150 min. liver ischemia followed by 70% hepatectomy and 24 hours reperfusion. Pigs in the DFO group received a continuous intravenous infusion of 100 mg/kg DFO. Liver remnant injury was evaluated by liver function tests, hepatic histology as well as serum and liver tissue malondialdehyde (MDA) concentrations. Deferoxamine-treated animals had reduced total bilirubin, γ-glutamyl transferase and ammonia levels as well as hepatocyte necrosis and oxidative injury. In a subsequent randomized clinical trial using DFO for I-R protection during major liver surgery, preliminary results revealed amelioration of hepatocellular damage, oxidative and inflammatory serum markers and apoptotic response in liver remnant biopsies.     

Involvement of platelet-activating factor in hepatic apoptosis and necrosis in chronic ethanol-fed rats given endotoxin

BACKGROUND/AIMS: Platelet-activating factor (PAF)-a potent activator of neutrophils-plays an important role in the pathogenesis of endotoxin-induced tissue injury. However, the role of PAF in hepatic damage during alcoholic hepatitis remains unclear. The aims of the present study were to test whether PAF contributes to hepatic injury in an animal model of alcoholic hepatitis and to investigate the involvement of the Fas-receptor/Fas-ligand system in this process. METHODS: Male Sprague-Dawley rats were pair-fed with Lieber-DeCarli ethanol liquid diet or isocaloric control diet for 6 weeks. Liver injury was induced by the intravenous (i.v.) injection of lipopolysaccharide (LPS) (1 mg/kg). Rats were pretreated with a specific PAF receptor antagonist (TCV-309; 100 mg/kg i.v.) or vehicle 1 h before LPS treatment. RESULTS: Chronic ethanol administration remarkably sensitized the rats to the effects of LPS, with resultant severe hepatocellular injury, accompanied by significant increases in serum levels of alanine aminotransferase (ALT), tumour necrosis factor (TNF)-alpha and interleukin (IL)-8 (CINC/gro). Histological examination of the damaged livers showed hepatocyte apoptosis and necrosis with extensive infiltration by neutrophils, whereas immunohistochemical studies revealed enhanced Fas-receptor expression on hepatocytes and hepatic accumulation of neutrophils expressing Fas-ligand. Pretreatment with the PAF receptor antagonist protected against hepatic injury, suppressing hepatocyte apoptosis and necrosis, infiltration of neutrophils, expression of Fas-receptor and Fas-ligand, and serum TNF-alpha levels. CONCLUSIONS: Our study suggests that PAF is an important mediator of hepatic injury in the ethanol/endotoxin model of alcoholic hepatitis.     

Protective effects of regulatory amino acids on ischemia-reperfusion injury in the isolated perfused rat liver

OBJECTIVE: Some amino acids (AAs) display potent regulatory activities on cell metabolism, including via anti-oxidative defences. The aim of this study was to evaluate the protective effect of these AAs on warm ischaemia-reperfusion (I/R) injury in the isolated perfused rat liver. MATERIAL AND METHODS: Livers from fasted male Sprague-Dawley rats were isolated and perfused without (control group) or with (AP group) a mixture of regulatory AAs (glutamine, histidine, leucine, methionine, proline, phenylalanine, tryptophan and alanine). After 45 min of perfusion, warm ischaemia was induced for 45 min by clamping the portal vein catheter; thereafter, reperfusion was performed for 30 min. RESULTS: TNF-alpha production was significantly lower in the AP group during reperfusion (Control: 39+/-7 versus AP: 16+/-2 pg min-1 g-1, p<0.05), and lactate dehydrogenase (LDH) release decreased significantly during the last 15 min of reperfusion (Control: 0.13+/-0.03 versus AP: 0.04+/-0.02 IU min-1 g-1, p<0.05), despite similar levels of oxidative stress. The addition of regulatory AAs was not associated with variations in portal flow, bile flow, hepatic glucose or urea metabolism. However, significant changes in intrahepatic glutamine (Control: 1.4+/-0.2 versus AP: 2.6+/-0.5 micromol g-1, p < 0.05) together with higher glutamate release in the AP group (Control: 10.2+/-5.4 versus AP: 42.6+/-10.9 nmol min-1 g-1, p < 0.05) indicated modifications in nitrogen metabolism. CONCLUSIONS: Taken together, the lower TNF-alpha production, suggesting decreased inflammatory response, the decrease in LDH release in the AP group, demonstrating a better preservation of liver viability, and the increase in hepatic glutamine indicate that AAs play an important role in the liver's response to I/R.     

Expression of macrophage inflammatory protein-1α in Kupffer cells following liver ischemia or reperfusion injury in rats

AIM: To explore the expression of macrophage inflammatory protein-1alpha (MIP-1alpha) in Kupffer cells (KCs) following liver ischemia/reperfusion injury IRI in rats. METHODS: Forty male SD rats were divided randomly into five groups. A model of partial warm ischemia/reperfusion injury in the rat liver was established. KCs were isolated and incubated one hour, six hours, 12 h, and 24 h after the reperfusion. Tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in the supernatants were measured by ELISA. MIP-1alpha in KCs was detected by immunocytochemical and RT-PCR. RESULTS: No or few MIP-1alpha protein and mRNA were expressed in the KCs of the control group. Its expression in the IRI group had a significant increase after the reperfusion (P < 0.05), which was contrary to the control group. CONCLUSION: The active behavior of the MIP-1alpha gene in KCs following liver ischemia/reperfusion injury is assumed to be one of the major causes for the hepatic ischemia/reperfusion injury.     

Effects of propofol on early phase of warm hepatic ischemia/reperfusion injury

BACKGROUND/AIMS: It is still unclear whether propofol may protect the liver against ischemia/ reperfusion injury (IRI) in vivo. METHODOLOGY: The livers of male Sprague-Dawley rats were subjected to 60 minutes of partial normothermic ischemia allowing perfusion to right and caudate lobes and subsequent 45 minutes of reperfusion. Either propofol (Propofol group, n = 11, 10 mg/ kg/h) or saline (Control group, n = 11) was continuously administered. At the end of reperfusion blood and liver samples were taken to analyze malondialdehyde, hepatic injury score, palmitate oxidation rate, serum AST and ALT concentrations. RESULTS: The malondialdehyde concentration (micromol/g tissue, mean +/- SD) was decreased in the Propofol group (1.39 +/- 0.21, perfused lobes and 1.85 +/- 0.27, ischemic reperfused lobes) compared with Control group (1.97 +/- 0.20, perfused lobes and 2.39 +/- 0.28, ischemic reperfused lobes) (P < 0.01). Hepatic injury scores were decreased in Propofol group compared with Control group (P < 0.01), but with mild hepatic injury in both groups. There were no differences of serum AST and ALT concentrations, and palmitate oxidation rate between groups. CONCLUSIONS: Propofol might be effective mainly in attenuation of lipid peroxidation with only minimal hepatocellular protection during the early phase of warm hepatic IRI in vivo.     

Protective effects of tumor necrosis factor α antibody and ulinastatin on liver ischemic reperfusion in rats

AIM: To study the protective effects of tumor necrosis factor α (TNFα) antibody and ulinastatin on liver ischemic reperfusion in rats.METHODS: One hundred and twenty male SD rats were randomly divided into four groups: normal control group, ischemic group, TNFα antibody group and TNFα antibody + ulinastatin group. The animals were killed at 0, 3, 6, 9, 12 h after ischemia for 60 min and followed by reperfusion. Serum alanine aminotransferase (ALT), malondialdehyde (MDA) and liver histopathology were observed.RESULTS: After ischemic reperfusion, the serum ALT and MDA were remarkably increased, and the hepatic congestion was obvious. Treatment of TNFα antibody and ulinastatin could significantly decrease serum ALT and MDA levels, and relieve hepatic congestion.CONCLUSION: Ulinastatin and TNFα antibody can suppress the inflammatory reaction induced by hepatic ischemic reperfusion, and have protective effects on rat hepatic ischemic reperfusion injury.     

Protective effects of tumor necrosis factor antibody and ulinastatin on liver ischemic reperfusion in rats

AIM: To study the protective effects of tumor necrosis factor α(TNFα) antibody and ulinastatin on liver ischemic reperfusion in rats.METHODS: One hundred and twenty male SD rats were randomly divided into four groups: normal control group,ischemic group, TNFα antibody group and TNFα antibody + ulinastatin group. The animals were killed at 0, 3, 6, 9,12 h after ischemia for 60 min and followed by reperfusion.Serum alanine aminotransferase (ALT), malondialdehyde (MDA) and liver histopathology were observed.RESULTS: After ischemic reperfusion, the serum ALT and MDA were remarkably increased, and the hepatic congestion was obvious. Treatment of TNFα antibody and ulinastatin could significantly decrease serum ALT and MDA levels,and relieve hepatic congestion.CONCLUSION: Ulinastatin and TNFα antibody can suppress the inflammatory reaction induced by hepatic ischemic reperfusion, and have protective effects on rat hepatic ischemic reperfusion injury.     

Ischemic preconditioning decreases C-X-C chemokine expression and neutrophil accumulation early after liver transplantation in rats

AIM: Polymorphonuclear neutrophil (PMN) plays a major role in liver ischemia/reperfusion injury. Protective effect of ischemic preconditioning (IP) has been confirmed in liver ischemia/reperfusion injury. The purpose of this study was to investigate the effect of IP on C-X-C chemokine expression and PMNs recruitment eady after liver transplantation.METHODS: Male Sprague-Dawley rats were used as donors and recipients of orthotopic liver transplantation (OLT). The donor liver was stored 24 hours in University of Wisconsin(UW) solution at 4 ℃ pre-implantation, IP was done by damp of the portal vein and hepatic artery of the donor liver for 10 minutes followed by reperfusion for 10 minutes before harvesting. The neutrophilic infiltration in liver was quantified using a myeloperoxidase (MPO) assay. Intragrafl: expression of macrophage inflammatory protein-2 (MIP-2) mRNA was investigated with in situ hybridization, The serum levels of MIP-2 and tumor necrosis factor (TNF)-α were also monitored,RESULTS: After liver transplantation without IP, the hepatic MPO increased significantly compared with sham operated group. In IP group, PMN in liver indicated by MPO was reduced significantly. In situ hybridization showed no MIP-2 mRNA in sham group but dramatic expression in hepatocytes in non-IP group. In IP group, MIP-2 mRNA was significantly down-regulated. Similarly, serum MIP-2 and TNF-α levels were significantly elevated in non-IP group and both were reduced in IP group.CONCLUSION: IP might protect graft liver from preservation-reperfusion injury after OLT through down-regulating C-X-C chemokine expression of hepatocytes, and alleviating PMNs recruitment after reperfusion.     

Attenuation of microcirculatory disturbance after liver ischemia by newly synthesized inflammatory cytokine suppressor,FR167653

BACKGROUND/AIMS: Inflammatory cytokines, such as interleukin-1 beta and tumor necrosis factor-alpha, which activate neutrophils, contribute to hepatic warm ischemia-reperfusion injury. However, the role of the cytokines in hepatic microcirculation immediately after reperfusion is still unclear. This study was carried out to investigate whether FR167653, a dual inhibitor of interleukin-1 beta and tumor necrosis factor-alpha, attenuates hepatic microcirculatory disturbance at the initial phase of reperfusion following liver ischemia. METHODOLOGY: Adult mongrel dogs were subjected to 90 minutes of liver ischemia by a Pringle's maneuver under portosystemic bypass. The animals were divided into two groups: a control group (n = 10), subjected to hepatic warm ischemia only, and a FR167653 administered group (n = 5), which received 1 mg/kg/h FR167653 for 4 hours since 30 minutes before the ischemia to 2 hours after the reperfusion continuously. Seven days animal survival, hepatic tissue blood flow, liver function test, hepatic venous blood concentration of endothelin-1 and plasminogen activator inhibitor-1, liver tissue biochemistry, and histopathology were analyzed. RESULTS: The treatment with FR167653 attenuated microcirculatory disturbance, lessened liver injury, enhanced adenine nucleotides resynthesis, and improved animal survival after liver ischemia. In addition, FR167653 significantly inhibited release of both endothelin-1 and plasminogen activator inhibitor-1 from the liver cells. CONCLUSIONS: These results suggest that the inflammatory cytokines induce microcirculatory disturbance in the initial phase of reperfusion following liver ischemia.