Ischemia/reperfusion injury in liver resection: a review of preconditioning methods. Surg Today. 2011;41:620-629. [PMID: 21533932 DOI: 10.1007/s00595-010-4444-4]

Protective effect of pinocembrin from Penthorum chinense Pursh on hepatic ischemia reperfusion injury via regulating HMGB1/TLR4 signal pathway

Hepatic ischemia-reperfusion injury (HIRI) is of common occurrence during liver surgery and transplantation. Pinocembrin (PIN) is a kind of flavonoid monomer extracted from the local traditional Chinese medicine Penthorum chinense Pursh (P. chinense). However, the effect of PIN on HIRI has not determined. We investigated the protective effect and potential mechanism of PIN against HIRI. Model mice were subjected to partial liver ischemia for 60 min, experimental mice were pretreated with PIN orally for 7 days, and H₂ O₂ -induced oxidative damage model in AML12 hepatic cells was established in vitro. Histopathologic analysis and serum biochemical levels revealed that PIN had hepatoprotective activities against HIRI. The variation of GSH, SOD, MDA, and ROS levels indicated that PIN treatments attenuated oxidative stress in tissue. PIN pretreatment obviously ameliorated apoptosis, and restrained the expression of HMGB1 and TLR4 in vivo. In vitro, compared with H₂ O₂ group, the contents of ROS, mitochondrial membrane potential, apoptotic cells, and Bcl-2 protein were decreased, while the Bax protein expression was increased. Moreover, HMGB-1 small interfering RNA test and western blotting showed that PIN pretreatment reduced HMGB1 and TLR4 protein levels. In conclusion, PIN pretreatment effectively protected hepatocytes from HIRI and inhibited the HMGB1/TLR4 signaling pathway.

Ischemic postconditioning improves the outcome of organs from donors after cardiac death in a pig liver transplantation model and provides synergistic protection with hypothermic machine perfusion

AIM

This study investigated whether ischemic postconditioning (IPO) improved the outcome of organs from donors after cardiac death and had a synergistic effect with hypothermic machine perfusion (HMP) in a pig liver transplantation model.

METHODS

A donor after cardiac death (DCD) model was developed in 48 healthy Bama miniature pigs randomly divided into four groups: simple cold storage group (SCS group), IPO group, HMP group, HMP-IPO group. The levels of serum alanine aminotransferase (ALT), total bilirubin, histopathological findings, apoptotic activity of hepatocytes, international normalized ratio (INR), tumor necrosis factor-α (TNF-α), and Malondialdehyde (MDA) were compared.

RESULTS

All recipients in the SCS group died within 6 h after transplantation. The livers of the recipients in the IPO had 50% survival on day 5. HMP allowed 83.3% survival and HMP-IPO allowed 100% survival. After reperfusion, the recipients in the IPO and HMP-IPO group had lower ALT and total bilirubin levels, less Suzuki score, less apoptosis, and less injury to hepatocytes and biliary ducts and attenuated inflammatory response and oxidative load.

CONCLUSIONS

IPO improved the outcome of organs from donors after cardiac death and had a synergistic effect with HMP in the pig liver transplantation model.

Tetramethylpyrazine inhibits neutrophil extracellular traps formation and alleviates hepatic ischemia/reperfusion injury in rat liver transplantation

Hepatic ischemia/reperfusion injury (IRI) is an adverse effect for liver transplantation which is characterized by immune response mediated inflammation. Recent studies report that neutrophil extracellular traps (NETs) are implicated in hepatic IRI. The aim of this study was to explore the mechanism of action of tetramethylpyrazine (TMP), the main chemical composition of Ligusticum chuanxiong in treatment of ischemic related diseases. Data showed that hepatic IRI increases the leak of alanine aminotransferase (ALT) and aspartate transaminase (AST), and stimulates formation of NETs. Extracellular DNA/NETs assay, hematoxylin-eosin (HE) staining, immunofluorescence assay, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) and Western blot assay, showed that TMP significantly reduces formation of NETs and alleviates hepatic IRI. Moreover, TMP and Diphenyleneiodonium (DPI) suppressed ROS production in neutrophils. In addition, analysis showed that activation of NADPH oxidase plays a role in formation of NETs triggered by hepatic IRI. Notably, TMP inhibited formation of NETs though inhibition of NADPH oxidase. Additionally, Combination treatment using TMP and DPI was more effective compared with monotherapy of either of the two drugs. These findings show that combination therapy using TMP and DPI is a promising method for treatment hepatic IRI.

Impact of Three Methods of Ischemic Preconditioning on Ischemia-Reperfusion Injury in a Pig Model of Liver Transplantation

BACKGROUND

Ischemic preconditioning (IPC), either direct (DIPC) or remote (RIPC), is a procedure aimed at reducing the harmful effects of ischemia-reperfusion (I/R) injury.

OBJECTIVES

To assess the local and systemic effects of DIPC, RIPC, and both combined, in the pig liver transplant model.

MATERIALS AND METHODS

Twenty-four pigs underwent orthotopic liver transplantation and were divided into 4 groups: control, direct donor preconditioning, indirect preconditioning at the recipient, and direct donor with indirect recipient preconditioning. The recorded parameters were: donor and recipient weight, graft-to-recipient weight ratio (GRWR), surgery time, warm and cold ischemia time, and intraoperative hemodynamic values. Blood samples were collected before native liver removal (BL) and at 0 h, 1 h, 3 h, 6 h, 12 h, 18 h, and 24 h post-reperfusion for the biochemical tests: aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), creatinine, BUN (blood urea nitrogen), lactate, total and direct bilirubin. Histopathological examination of liver, gut, kidney, and lung fragments were performed, as well as molecular analyses for expression of the apoptosis-related BAX (pro-apoptotic) and Bcl-XL (anti-apoptotic) genes, eNOS (endothelial nitric oxide synthase) gene, and IL-6 gene related to inflammatory ischemia-reperfusion injury, using real-time polymerase chain reaction (RT-PCR).

RESULTS

There were no differences between the groups regarding biochemical and histopathological parameters. We found a reduced ratio between the expression of the BAX gene and Bcl-XL in the livers of animals with IPC versus the control group.

CONCLUSIONS

DIPC, RIPC or a combination of both, produce beneficial effects at the molecular level without biochemical or histological changes.

Metalloproteinase expression after desflurane preconditioning in hepatectomies: A randomized clinical trial

BACKGROUND

Hepatectomy with inflow occlusion results in ischemia-reperfusion injury; however, pharmacological preconditioning can prevent such injury and optimize the postoperative recovery of hepatectomized patients. The normal inflammatory response after a hepatectomy involves increased expression of metalloproteinases, which may signal pathologic hepatic tissue reformation.

AIM

To investigate the effect of desflurane preconditioning on these inflammatory indices in patients with inflow occlusion undergoing hepatectomy.

METHODS

This is a single-center, prospective, randomized controlled trial conducted at the 4^th Department of Surgery of the Medical School of Aristotle University of Thessaloniki, between August 2016 and December 2017. Forty-six patients were randomized to either the desflurane treatment group for pharmacological preconditioning (by replacement of propofol with desflurane, administered 30 min before induction of ischemia) or the control group for standard intravenous propofol. The primary endpoint of expression levels of matrix metalloproteinases and their inhibitors was determined preoperatively and at 30 min posthepatic reperfusion. The secondary endpoints of neutrophil infiltration, coagulation profile, activity of antithrombin III (AT III), protein C (PC), protein S and biochemical markers of liver function were determined for 5 d postoperatively and compared between the groups.

RESULTS

The desflurane treatment group showed significantly increased levels of tissue inhibitor of metalloproteinases 1 and 2, significantly decreased levels of matrix metalloproteinases 2 and 9, decreased neutrophil infiltration, and less profound changes in the coagulation profile.  During the 5-d postoperative period, all patients showed significantly decreased activity of AT III, PC and protein S (vs baseline values, P < 0.05). The activity of AT III and PC differed significantly between the two groups from postoperative day 1 to postoperative day 5 (P < 0.05), showing a moderate drop in activity of AT III and PC in the desflurane treatment group and a dramatic drop in the control group. Compared to the control group, the desflurane treatment group also had significantly lower international normalized ratio values on all postoperative days (P < 0.005) and lower serum glutamic oxaloacetic transaminase and serum glutamic pyruvic transaminase values on postoperative days 2 and 3 (P < 0.05).   Total length of stay was significantly less in the desflurane group (P = 0.009).

CONCLUSION

Desflurane preconditioning can lessen the inflammatory response related to ischemia-reperfusion injury and may shorten length of hospitalization.

An Extra Breath of Fresh Air: Hyperbaric Oxygenation as a Stroke Therapeutic

Stroke serves as a life-threatening disease and continues to face many challenges in the development of safe and effective therapeutic options. The use of hyperbaric oxygen therapy (HBOT) demonstrates pre-clinical effectiveness for the treatment of acute ischemic stroke and reports reductions in oxidative stress, inflammation, and neural apoptosis. These pathophysiological benefits contribute to improved functional recovery. Current pre-clinical and clinical studies are testing the applications of HBOT for stroke neuroprotection, including its use as a preconditioning regimen. Mild oxidative stress may be able to prime the brain to tolerate full extensive oxidative stress that occurs during a stroke, and HBOT preconditioning has displayed efficacy in establishing such ischemic tolerance. In this review, evidence on the use of HBOT following an ischemic stroke is examined, and the potential for HBOT preconditioning as a neuroprotective strategy. Additionally, HBOT as a stem cell preconditioning is also discussed as a promising strategy, thus maximizing the use of HBOT for ischemic stroke.

Can Viscoelasticity Measurements Obtained Through Shear-Wave US Elastography be used to Monitor Hepatic Ischemia-Reperfusion Injury and Treatment Response? An Animal Study

This study aimed to investigate whether viscoelasticity measurements can be used to quantitatively analyze and monitor therapy response in hepatic ischemia-reperfusion injury (HIRI). All animals were divided into three groups: a sham operation group (n = 12), an ischemia-reperfusion injury (IRI) group (n = 12) and an andrographolide pre-treatment group (n = 6). To assess the feasibility of using shear-wave velocity (SWV) and shear-wave dispersion (SWD), shear-wave ultrasound elastography was applied onto IRI rats after 4 and 24 h of reperfusion or sham operation (each time point subgroup n = 6). For the verification experiments, six additional rats received andrographolide injection 2 h before IRI and were examined 24 h after reperfusion. The rats were sacrificed for biochemical and histopathological analyses after ultrasound scanning was performed. Compared with the sham group, the IRI group exhibited significantly higher SWD after both 4 and 24 h of reperfusion（10.69 ± 0.69 vs. 15.20 ± 3.23 and 9.01 ± 0.46 vs. 19.35 ± 0.86; p < 0.05). A positive correlation was found between SWD values and Suzuki's score (r = 0.621; p < 0.05). No correlation was found between SWV and Suzuki's score (r = 0.283; p > 0.05), although significant differences were found between the two groups after 24 h of reperfusion. Andrographolide treatment resulted in a significantly decreased SWD (15.24 ± 0.45 vs. 19.35 ± 0.86; p < 0.05), whereas SWV showed no statistically significant difference. This study demonstrated the potential of using viscoelasticity measurements for the diagnosis and therapeutic monitoring of HIRI, and that the use of SWD was significantly more advantageous than SWV.

OTUD4 alleviates hepatic ischemia-reperfusion injury by suppressing the K63-linked ubiquitination of TRAF6

Hepatic ischemia-reperfusion (IR) injury can cause serious liver damage, leading to liver dysfunction after liver surgery, which is associated with NF-κB-mediated inflammation. The K63-linked auto-polyubiquitination of tumor necrosis factor receptor-associated factor 6 (TRAF6) is essential for the activation of NF-κB. Here, we found that OTU domain-containing protein 4 (OTUD4), a deubiquitinating enzyme (DUB), interacts with TRAF6 and decreases the K63 auto-polyubiquitination of TRAF6. In addition, the data showed that NF-κB activation was impaired and inflammatory factor levels were reduced after overexpressing OTUD4 in a hypoxia/reoxygenation (HR) model and a hepatic IR model. Additionally, the liver inflammatory response and tissue damage were ameliorated in mice overexpressing OTUD4.Taken together, these results show that OTUD4 can negatively regulate NF-κB activation by suppressing the K63-linked ubiquitination of TRAF6, thus alleviating hepatic ischemia-reperfusion injury.

Effect of remote ischemic preconditioning on hepatic ischemia-reperfusion injury in patients undergoing liver resection: a randomized controlled trial

BACKGROUND

Studies in animal models have shown that remote ischemic preconditioning (RIPC) could protect the liver from hepatic ischemia-reperfusion injury (HIRI). The aim of this study was to examine whether RIPC could reduce HIRI in patients undergoing liver resection.

METHODS

A total of 120 patients were randomly assigned to three groups: a control group receiving no conditioning, an ischemic preconditioning (IPC) group, and an RIPC group. In the IPC group, the hepatoduodenal ligament was blocked for 10 min followed by 10 min of reperfusion prior to hepatic resection. Patients in the RIPC group received three cycles of 5-min ischemia followed by 5-min reperfusion to the right arm. Alanine transaminase (ALT), aspartate transaminase (AST), and tumor necrosis factor-like weak inducer of apoptosis (TWEAK) were examined before and after surgery.

RESULTS

A total of 105 patients completed the trial: 39 in the control group, 32 in the IPC group, and 34 in the RIPC group. In comparison to the control, serum ALT and AST levels significantly decreased in the IPC (ALT: 507.0±401.3 vs. 1040.7±649.5 IU/L, P<0.001; AST: 495.8±369.4 vs. 935.9±640.7 IU/L, P=0.001) and RIPC (ALT: 680.8±291.5 vs. 1040.7±649.5 IU/L, P=0.002; AST: 661.7±290.6 vs. 935.9±640.7 IU/L, P=0.014) groups on the first postoperative day. In comparison to the control, TWEAK significantly decreased in the IPC group (IPC 57.99±17.8 vs. control 76.13±12.4 ng/L, P=0.025) after surgery. TWEAK did not differ between the RIPC and IPC groups (RIPC 64.84±14.2 vs. IPC 57.99±17.8 ng/L, P=0.385).

CONCLUSIONS

RIPC could reduce hepatic ischemia-reperfusion injury after liver resection.

Ethyl pyruvate improves skin flap survival after ischaemia reperfusion injury

BACKGROUND & OBJECTIVES

Reperfusion after ischaemia is detrimental to the tissues. The oxidative stress created and cytokines released are mostly responsible in this process. In this study, ethyl pyruvate, a known agent for its anti-inflammatory and antioxidant properties, was used to investigate the effects on ischaemia/reperfusion injury on skin island flaps in rats.

METHODS

Sixty rats were randomly distributed in three groups (non-ischaemic, ischaemic and medication groups). Ethyl pyruvate was administered in the medication group with a dose of 50 mg/kg. After 24 h and one week, the animals were sacrificed, and the flaps were analyzed macroscopically, histopathologically, biochemically (total nitrite, malondialdehyde and myeloperoxidase).

RESULTS

Biochemical markers indicating oxidative stress, were found elevated in ischaemic group, whereas medication with ethyl pyruvate significantly reduced these values. There was a significant reduction (P<0.05) in the levels of these markers between ischaemic and medication groups. Ethyl pyruvate improved all the parameters significantly.

INTERPRETATION & CONCLUSION

Ethyl pyruvate showed strong scavenger activity against reactive oxygen species. It could be a potential candidate to improve the flap viability in reconstructive microsurgery, especially in free tissue transfers. However, more studies are warranted in experimental models to confirm these findings.

Salidroside pretreatment attenuates apoptosis and autophagy during hepatic ischemia-reperfusion injury by inhibiting the mitogen-activated protein kinase pathway in mice

Ischemia–reperfusion injury (IRI) contributes to liver damage in many clinical situations, such as liver resection and liver transplantation. In the present study, we investigated the effects of the antioxidant, anti-inflammatory, and anticancer agent salidroside (Sal) on hepatic IRI in mice. The mice were randomly divided into six groups: normal control, Sham, Sal (20 mg/kg), IRI, IRI + Sal (10 mg/kg), and IRI + Sal (20 mg/kg). We measured liver enzymes, proinflammatory cytokines, TNF-α and interleukin-6, and apoptosis- and autophagy-related marker proteins at 2, 8, and 24 hours after reperfusion. Components of mitogen-activated protein kinase (MAPK) signaling, including P-38, jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK), were also measured using an MAPK activator anisomycin to deduce their roles in hepatic IRI. Our results show that Sal safely protects hepatocytes from IRI by reducing levels of liver enzymes in the serum. These findings were confirmed by histopathology. We concluded that Sal protects hepatocytes from IRI partly by inhibiting the activation of MAPK signaling, including the phosphorylation of P38, JNK, and ERK. This ameliorates inflammatory reactions, apoptosis, and autophagy in the mouse liver.

Curcumin protects against hepatic ischemia/reperfusion induced injury through inhibiting TLR4/NF-κB pathway

The TLR4/NF-κB pathway had important roles in hepatic ischemia/reperfusion (I/R) injury. In this study, we reported a protective effect of curcumin against hepatic I/R injury via TLR4/NF-κB pathway. Curcumin significantly inhibited cell apoptosis, and decreased levels of LDH and production of TNF-a, IL-1b, and IL-6 in the cell supernatant. In addition, curcumin ameliorated elevated TLR4 and NF-κB caused by hypoxia/reoxygenation stimulation in BRL-3A cells. In vivo assays revealed that curcumin reduce levels of ALT and AST, and reversed TLR4/NF-κB signaling pathway caused by hepatic I/R stimulation in liver tissues. These results suggested that curcumin ameliorates hepatic I/R injury, which may be mediated in part via the TLR4/NF-κB signaling pathway.

Protective Effect of Eupatilin Pretreatment Against Hepatic Ischemia-Reperfusion Injury in Mice

BACKGROUND

Eupatilin, a pharmacologically active flavone derived from Artemisia species, is known to have antioxidant and antiinflammatory activities. Ischemia-reperfusion injury (IRI) is a major critical event that commonly occurs after liver transplantation and resection. Furthermore, inflammatory responses to IRI exacerbate the resultant hepatic injury. In this study, we investigated whether eupatilin protects against IR-induced acute liver injury in mice.

MATERIALS AND METHODS

Partial (70%) hepatic IRI was induced in male C57BL/6 mice by portal triad pedicle occlusion for 90 minutes followed by reperfusion for 6 hours. Eupatilin (10 mg/kg body weight, oral) was administered 4 days before the IRI.

RESULTS

Treatment with eupatilin significantly decreased serum alanine aminotransferase and serum aspartate aminotransferase as well as liver histologic changes. Eupatilin also prevented hepatic glutathione depletion and increased malondialdehyde levels induced by IRI. Western blotting indicated that eupatilin significantly increased the levels of heat shock protein and B-cell lymphoma 2 protein, attenuated inducible nitric oxide synthase, and cleaved caspase-3 levels 6 hours after IRI. The expression of the Toll-like receptor 2/4, and phosphorylated nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor was significantly decreased in the eupatilin pretreatment group.

CONCLUSIONS

Eupatilin improved the acute hepatic IRI by reducing inflammation and apoptosis. These findings suggest that eupatilin is a promising therapeutic agent against acute IR-induced hepatic damage.

Beyond Preconditioning: Postconditioning as an Alternative Technique in the Prevention of Liver Ischemia-Reperfusion Injury

Liver ischemia/reperfusion injury may significantly compromise hepatic postoperative function. Various hepatoprotective methods have been improvised, aiming at attenuating IR injury. With ischemic preconditioning (IPC), the liver is conditioned with a brief ischemic period followed by reperfusion, prior to sustained ischemia. Ischemic postconditioning (IPostC), consisting of intermittent sequential interruptions of blood flow in the early phase of reperfusion, seems to be a more feasible alternative than IPC, since the onset of reperfusion is more predictable. Regarding the potential mechanisms involved, it has been postulated that the slow intermittent oxygenation through controlled reperfusion decreases the burst production of oxygen free radicals, increases antioxidant activity, suppresses neutrophil accumulation, and modulates the apoptotic cascade. Additionally, favorable effects on mitochondrial ultrastructure and function, and upregulation of the cytoprotective properties of nitric oxide, leading to preservation of sinusoidal structure and maintenance of blood flow through the hepatic circulation could also underlie the protection afforded by postconditioning. Clinical studies are required to show whether biochemical and histological improvements afforded by the reperfusion/reocclusion cycles of postconditioning during early reperfusion can be translated to a substantial clinical benefit in liver resection and transplantation settings or to highlight more aspects of its molecular mechanisms.

Effect of remote ischemic preconditioning in the expression of IL-6 and IL-10 in a rat model of liver ischemia-reperfusion injury

PURPOSE

To study the effect of remote ischemic preconditioning (RIPC) in ischemia-reperfusion (I/R) liver injury and in the expression of IL-6 and IL-10 in a rat model.

METHODS

Thirty-six male rats were divided in three groups: Sham; I/R injury, a 45 minutes lobar liver ischemia and reperfusion; and RIPC, six cycles of four minutes of ischemia and four minutes of reperfusion on the right hindlimb followed by a 45 minutes lobar liver ischemia and reperfusion. Tissue and blood samples were collected after 1h and 3h of reperfusion for histopathological study, plasma cytokines and alanine aminotransferase (ALT) measurement.

RESULTS

The histopathological study demonstrated a significant reduction in liver necrosis in the RIPC group (p<0,001). The ALT levels were also significant lower in the RIPC group (p<0.01). The cytokines assessment showed that IL-6 levels were increased in the RIPC group after 1h of reperfusion, in comparison to the I/R group (p<0.05). Interleukin-10 levels in RIPC groups did not differ significantly from I/R group.

CONCLUSIONS

Remote ischemic preconditioning is effective in decreasing liver necrosis in a rat model of ischemia-reperfusion. The IL-6 expression is up-regulated and peaked at 60 min of reperfusion. There was no difference in IL-10 expression between the groups.

Variable Pringle Maneuvers and Effect on Intestinal Epithelium in Rats. A Pilot Experimental Study in Rats

BACKGROUND

It is observed that combined liver and colon surgery especially when this includes major liver resection with Pringle maneuver (PM) performance does not have a favorable outcome. Aim of our experimental study is to investigate the impact of portal triad occlusion on the large bowel and intra-abdominal inflammation and potent protective effects of the variants of (PM) in the combined surgical cases.

MATERIALS AND METHODS

Forty-four rats were divided into four groups. In group A (control group), 1cm of the left partial colon was resected and then an end-to-end anastomosis was performed. In group B, a continuous PM for 30 minutes was performed followed by resection of 1cm of the left colon and an end-to-end anastomosis. In group C, the left colonic resection and anastomosis was performed after intermittent PM (IPM), which was 10 minutes PM followed by 5 minutes reperfusion repeated for three circles. In group D, an ischemic preconditioning for 10 minutes was initially performed followed by 5 minutes reperfusion and then continuous PM for 30 minutes. Finally the rats in group D underwent a 1cm left colonic resection and an end-to-end anastomosis.

RESULTS

The percentage of colitis was higher in the B group (P = 0,19). The percentage of inflammation was not significantly higher even when we compared all "occlusion" groups (B+C+D) with the sham group. No evidence of pancreatitis was found in the sham group whereas amylase and lipase levels were higher in Groups B, C and D together (P = 0,0267). The comparison of group A to group B showed a significant difference (P = 0,0014) caused by continuous PM for 30 minutes, but there was no such result after IPM.

CONCLUSIONS

Major liver resections are performed with PM in order to minimize intra-operative blood loss. In the combined cases of colon surgery and major liver resections where PM is needed our results showed that IPM presents with better outcome and could be preferred compared with the other PM variants.

Hypoxia preconditioning induced HIF-1α promotes glucose metabolism and protects mitochondria in liver I/R injury

BACKGROUND

Ischemia and reperfusion (I/R) injury is one of the main lesions after liver transplantation. This study aims to detect hypoxia-induced HIF-1α protects transplanted liver against I/R injury by promoting glucose metabolism to decrease mitochondrial injury and apoptosis on rat model.

METHODS

The rats were given a treatment of 90 min non-lethal hypoxic preconditioning to induce and increase the HIF-1α expression. The autologous orthotopic liver transplantation model was used to imitate liver I/R injury.

RESULTS

Hypoxic-induced HIF-1α was detected to increase in liver tissue after 90-minute hypoxic environment (HP vs. Ctrl, *P<0.001). After operation, the expression of HIF-1α in liver tissue was also stayed at a high level. At 24h after operation, several genes were promoted, such as the levels of HK-2 (HP vs. AT, 24h, *P=0.004), Lactate dehydrogenase (LDHA) (HP vs. AT, 24h, *P=0.003), pyruvate dehydrogenase kinase (PDK-1) (HP vs. AT, 24h, *P=0.007), even the NF-κB and Erk pathways. From the TUNEL assay, the apoptosis in hypoxic preconditioning liver tissue was decreased compared with non-HP operative group at 12h after operation. The expressions of cleaved-caspase 3 (HP vs. AT, *P=0.0119) and PARP (HP vs. AT, *P=0.0134) in HP group were also significantly lower than AT group.

CONCLUSION

The hypoxia-induced HIF-1α could promote glucose metabolism to protect hepatocellular mitochondria from damage. It could be a useful way to protect liver against I/R injuries and inflammatory injury, and particularly promote the recovery of graft function.

Erythropoietin pretreatment exerts anti-inflammatory effects in hepatic ischemia/reperfusion-injured rats via suppression of the TLR2/NF-κB pathway

INTRODUCTION

The inflammatory response plays an important role in liver dysfunction after hepatic ischemia/reperfusion (I/R), which is tightly regulated by the Toll-like receptor 2 (TLR2)/nuclear factor (NF)-κB pathway; suppression of TLR2/NF-κB signaling has therefore become a promising target for anti-inflammatory treatment in hepatic I/R injury. Erythropoietin (EPO) is a glycoprotein cytokine produced primarily by the kidney that has anti-inflammatory activities. The purpose of the present study was to investigate the effect of EPO preconditioning, if any, against hepatic I/R injury in rats and its underlying mechanisms.

MATERIALS AND METHODS

Male Sprague-Dawley rats were subjected to partial (70%) hepatic ischemia for 45 minutes after pretreatment with either saline or EPO followed by 24-hour reperfusion. Hepatic injury was evaluated according to biochemical and histopathologic examinations. The expression of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) were measured by using enzyme-linked immunosorbent assay and real-time polymerase chain reaction. The expression of nuclear translocation and phosphorylation of NF-κB p65, EPOR receptor (EPOR), p-EPOR, p-IκB-α, IκB-α, and TLR2 were determined by using Western blot analysis.

RESULTS

EPO treatment significantly improved hepatic function and histology, as indicated by reduced transaminase levels and pathologic changes. The expression of TNF-α, IL-1β, IL-6, p-IκB-α, and TLR2 was significantly decreased with up-regulation of p-EPOR by EPO. Moreover, EPO pretreatment also reduced I/R-induced the phosphorylation and nuclear translocation of NF-κB p65 subunits in liver tissue, but EPO had no influence on the expression of p65 and IκB-α.

CONCLUSIONS

These results suggest that EPO pretreatment ameliorates hepatic I/R injury, which is involved in suppressing TLR2/NF-κB-mediated inflammation.

Attenuation of Oxidative Stress by Ischemic Preconditioning in an Experimental Model of Intraabdominal Hypertension

PURPOSE

Increased intra-abdominal pressure, as used in laparoscopic surgery or seen in intraabdominal hypertension (IAH), is associated with tissue ischemia and oxidative stress. Ischemic preconditioning (IP) is a method successfully used in liver and transplant surgery, in order to attenuate the detrimental effects of ischemia and reperfusion. In this experimental study, we tested the ability of IP to modify oxidative stress induced by extremely high intraabdominal pressures.

METHODS

Twenty-five female pigs were studied and divided in three groups: a control group, a pneumoperitoneum group (with pressure of 30 mmHg), and an ischemic preconditioning group (initially subjected to preconditioning with pressure of 25 mmHg for 15 min and desufflation for 15 min and then to pneumoperitoneum as in pneumoperitoneum group). Blood samples were obtained at identical time intervals in the three groups. Total oxidative capacity, total antioxidative capacity and total nitric oxide (NO), nitrite and nitrate concentrations were measured and compared between groups.

RESULTS

IP increased total antioxidative capacity (p = .045) and protective mediators like nitrite (p = .022). It was also associated with a trend toward lower levels of total oxidative capacity at the end of the abdominal desufflation period but statistical significance was not met.

CONCLUSIONS

IP attenuated oxidative stress induced by IAH, mainly by increasing antioxidative capacity and the levels of protective mediators. The fact that IP was effective, even when used at extremely high levels of intraabdominal pressure, reinforces the interest on this method but further studies are needed to clarify its mechanism of action and potential clinical applications.

Hyperoxic preconditioning in partial liver ischemia

PURPOSE

To evaluate the effect of the hyperbaric oxygen (HBO) treatment as a pre-conditioning for I/R effects in the liver ischemia.

METHODS

Fifty-seven male Wistar rats (260-300g) were submitted to the following procedures: SHAM; I/R, rats submitted to I/R, consisting of partial ischemia of 70% of the liver for 90 minutes followed by 15 minutes of reperfusion; HBO I/R 1 ATA, 30 minutes of HBO treatment at the pressure of 1 absolute atmosphere (ATA) during the ischemia time. HBO I/R 2 ATA, 30 minutes of HBO (2 ATA) during the ischemia time. Pre HBO I/R 30', rats submitted to 30 minutes of HBO (2 ATA) immediately before the I/R time. Pre HBO I/R 90', rats submitted to 90 minutes of HBO (2 ATA) immediately before the I/R time.

RESULTS

There was a significant worsening of all the parameters of mitochondrial energy production (state 3, 4, RCR and Swelling) in the I/R group, when compared to the Sham group (I/R <Sham, p<0.05). There was also a significant worsening in state 4, RCR and mitochondrial edema in the Pre HBO I/R 90' group compared to the I/R group. Hepatic enzyme concentrations were significantly higher in the I/R group.

CONCLUSION

The use of hyperbaric oxygen before and during I/R did not improve the production of hepatocellular energy reduced by I/R, nor did it prevent the installation of mitochondrial edema induced by Iischemia/reperfusion.

Intestinal ischemic preconditioning ameliorates hepatic ischemia/reperfusion injury in rats: role of heme oxygenase 1 in the second window of protection

Preconditioning by brief ischemia protects not only the concerned organ but also other distant organs against subsequent lethal damage; this is called remote ischemic preconditioning (RIPC). This study was designed to investigate the impact of intestinal RIPC on hepatic ischemia/reperfusion injury (IRI) with a special interest in heme oxygenase 1 (HO-1) induction in the second window of protection (SWOP). Male Wistar rats were randomly assigned to 1 of 2 groups: an RIPC group or a sham group. Before hepatic IRI, either intestinal RIPC, consisting of 2 cycles of 4-minute superior mesenteric artery clamping separated by 11 minutes of declamping (RIPC group), or a sham procedure (sham group) was performed. After 48 hours of recovery, the rats were exposed to 30 minutes of total hepatic IRI. Transaminase releases and proinflammatory cytokines were determined at several time points after reperfusion. Histopathological analysis and animal survival were also investigated. Intestinal RIPC significantly lowered transaminase release (alanine aminotransferase at 2 hours: 873.3 ± 176.4 IU/L for the RIPC group versus 3378.7 ± 871.1 IU/L for the sham group, P < .001) as well as proinflammatory cytokine production (tumor necrosis factor α at 2 hours: 930 ± 42 versus 387 ± 17 pg/μL, P < .001). The morphological integrity of the liver and the ileum was maintained significantly better with intestinal RIPC; this reached statistical significance not only in Suzuki's liver injury score (3.5 ± 0.2 versus 0.7 ± 0.5, P = .007) but also in Park's score for intestinal damage (4.0 ± 0.4 versus 2.0 ± 0.2, P = .007). Animal survival was also markedly improved (83.1% versus 15.4%, P < .001). As a mechanism underlying this protection, HO-1 was substantially induced in liver tissue, especially in hepatocytes, with remarkable up-regulation of bradykinin in the portal blood, whereas HO-1 protein induction in enterocytes was not significant. In conclusion, intestinal RIPC remarkably attenuates hepatic IRI in the SWOP, presumably by HO-1 induction in hepatocytes.

N-acetylcysteine attenuates ischemia-reperfusion-induced apoptosis and autophagy in mouse liver via regulation of the ROS/JNK/Bcl-2 pathway

BACKGROUND

Hepatic ischemia-reperfusion injury (HIRI) remains a pivotal clinical problem after hemorrhagic shock, transplantation, and some types of toxic hepatic injury. Apoptosis and autophagy play important roles in cell death during HIRI. It is also known that N-acetylcysteine (NAC) has significant pharmacologic effects on HIRI including elimination of reactive oxygen species (ROS) and attenuation of hepatic apoptosis. However, the effects of NAC on HIRI-induced autophagy have not been reported. In this study, we evaluated the effects of NAC on autophagy and apoptosis in HIRI, and explored the possible mechanism involved.

METHODS

A mouse model of segmental (70%) hepatic warm ischemia was adopted to determine hepatic injury. NAC (150 mg/kg), a hepatoprotection agent, was administered before surgery. We hypothesized that the mechanism of NAC may involve the ROS/JNK/Bcl-2 pathway. We evaluated the expression of JNK, P-JNK, Bcl-2, Beclin 1 and LC3 by western blotting and immunohistochemical staining. Autophagosomes were evaluated by transmission electron microscopy (TEM).

RESULTS

We found that ALT, AST and pathological changes were significantly improved in the NAC group. Western blotting analysis showed that the expression levels of Beclin 1 and LC3 were significantly decreased in NAC-treated mice. In addition, JNK, p-JNK, Bax, TNF-α, NF-κB, IL2, IL6 and levels were also decreased in NAC-treated mice.

CONCLUSION

NAC can prevent HIRI-induced autophagy and apoptosis by influencing the JNK signal pathway. The mechanism is likely to involve attenuation of JNK and p-JNK via scavenged ROS, an indirect increase in Bcl-2 level, and finally an alteration in the balance of Beclin 1 and Bcl-2.

Tumour necrosis factor-α promotes liver ischaemia-reperfusion injury through the PGC-1α/Mfn2 pathway

Tumour necrosis factor (TNF)-α has been considered to induce ischaemia-reperfusion injury (IRI) of liver which is characterized by energy dysmetabolism. Peroxisome proliferator–activated receptor-γ co-activator (PGC)-1α and mitofusion2 (Mfn2) are reported to be involved in the regulation of mitochondrial function. However, whether PGC-1α and Mfn2 form a pathway that mediates liver IRI, and if so, what the underlying involvement is in that pathway remain unclear. In this study, L02 cells administered recombinant human TNF-α had increased TNF-α levels and resulted in down-regulation of PGC-1α and Mfn2 in a rat liver IRI model. This was associated with hepatic mitochondrial swelling, decreased adenosine triphosphate (ATP) production, and increased levels of reactive oxygen species (ROS) and alanine aminotransferase (ALT) activity as well as cell apoptosis. Inhibition of TNF-α by neutralizing antibody reversed PGC-1α and Mfn2 expression, and decreased hepatic injury and cell apoptosis both in cell culture and in animals. Treatment by rosiglitazone sustained PGC-1α and Mfn2 expression both in IR livers, and L02 cells treated with TNF-α as indicated by increased hepatic mitochondrial integrity and ATP production, reduced ROS and ALT activity as well as decreased cell apoptosis. Overexpression of Mfn2 by lentiviral-Mfn2 transfection decreased hepatic injury in IR livers and L02 cells treated with TNF-α. However, there was no up-regulation of PGC-1α. These findings suggest that PGC-1α and Mfn2 constitute a regulatory pathway, and play a critical role in TNF-α-induced hepatic IRI. Inhibition of the TNF-α or PGC-1α/Mfn2 pathways may represent novel therapeutic interventions for hepatic IRI.

Ethyl pyruvate ameliorates hepatic ischemia-reperfusion injury by inhibiting intrinsic pathway of apoptosis and autophagy

BACKGROUND

Hepatic ischemia-reperfusion (I/R) injury is a pivotal clinical problem occurring in many clinical conditions such as transplantation, trauma, and hepatic failure after hemorrhagic shock. Apoptosis and autophagy have been shown to contribute to cell death in hepatic I/R injury. Ethyl pyruvate, a stable and simple lipophilic ester, has been shown to have anti-inflammatory properties. In this study, the purpose is to explore both the effect of ethyl pyruvate on hepatic I/R injury and regulation of intrinsic pathway of apoptosis and autophagy.

METHODS

Three doses of ethyl pyruvate (20 mg/kg, 40 mg/kg, and 80 mg/kg) were administered 1 h before a model of segmental (70%) hepatic warm ischemia was established in Balb/c mice. All serum and liver tissues were obtained at three different time points (4 h, 8 h, and 16 h).

RESULTS

Alanine aminotransferase (ALT), aspartate aminotransferase (AST), and pathological features were significantly ameliorated by ethyl pyruvate (80 mg/kg). The expression of Bcl-2, Bax, Beclin-1, and LC3, which play an important role in the regulation of intrinsic pathway of apoptosis and autophagy, was also obviously decreased by ethyl pyruvate (80 mg/kg). Furthermore, ethyl pyruvate inhibited the HMGB1/TLR4/ NF-κb axis and the release of cytokines (TNF-α and IL-6).

CONCLUSION

Our results showed that ethyl pyruvate might attenuate to hepatic I/R injury by inhibiting intrinsic pathway of apoptosis and autophagy, mediated partly through downregulation of HMGB1/TLR4/ NF-κb axis and the competitive interaction with Beclin-1 of HMGB1.

A prospective randomized controlled trial to compare pringle manoeuvre with hemi-hepatic vascular inflow occlusion in liver resection for hepatocellular carcinoma with cirrhosis

BACKGROUND

The duration of hepatic vascular inflow occlusion and the amount of intraoperative blood loss have significant negative impacts on postoperative morbidity, mortality and long-term survival outcomes of patients who receive partial hepatectomy for hepatocellular carcinoma (HCC) with cirrhosis.

AIM

This study aimed to compare the perioperative outcomes of partial hepatectomy for HCC superimposed on hepatitis B-related cirrhosis using two different occlusion techniques.

METHODS

A randomized controlled trial was carried out to evaluate the impact of two different vascular inflow occlusion techniques. The postoperative short-term results were compared.

RESULTS

During the study period, 252 patients received partial hepatectomy for HCC with cirrhosis. Of these patients, 120 were randomized equally into two groups: the Pringle manoeuvre group (n = 60) and the hemi-hepatic vascular inflow occlusion group (n = 60). The number of patients who had poor liver function on postoperative day 5 with ISLGS grade B or worse was 24 and 13, respectively (P = 0.030). The postoperative complication rate was significantly higher in the Pringle manoeuvre group (40 versus 22 %, P = 0.030). However, the Pringle manoeuvre group had significantly shorter operating time (116 versus 136 min, P = 0.012) although there was no significant difference in intraoperative blood loss between the two groups [200 ml (range 10-5,000 ml) versus 300 ml (range 100-1,000 ml); P = 0.511]. There was no perioperative mortality.

CONCLUSIONS

The results indicated that for patients with HCC with cirrhosis, hemi-hepatic vascular inflow occlusion was a better inflow occlusion method than Pringle manoeuvre.

[Data on liver enzyme and histological changes caused by intermittent clampings of the hepatoduodenal ligament in an experimental model]

Intermittent compression of the structures of the hepatoduodenal ligament, is often performed during liver surgery. As a result, changes in hepatic blood supply and consequent reperfusion induced tissue damages will develop. Ischemia-reperfusion injury, which occur in local and distant regions, influence outcome of hepatic surgery, and it is in close correlation with the duration of hypoxia during the intervention. In animal model the effect of Baron/Pringle manoeuvre was investigated in terms of changes in liver function tests and histology. The study was carried out on 12 Beagle dogs, clamping of the hepatoduodenal ligament for 3×15 minutes then half an hour reperfusion was performed followed by blood and tissue sampling. Significant histological changes were observed both in the liver as well as the small intestine. In terms of liver function changes, GPT elevation occurred the earliest, GOT and LDH were also increased at the end of the 30 minutes reperfusion. In this animal model, the third 15 minutes compression turned out to be too long. Elevation in GPT levels was the most sensitive marker.

How does moxibustion possibly work?

"Acupmoxa" is a hybrid word of "acupuncture" and "moxibustion" that more closely resembles the Chinese ideograph for this treatment. People in Western countries are more familiar with acupuncture, while moxibustion is less popular, partially due to the paucity of scientific studies. Although the evidence-based efficacy of moxibustion needs to be further clarified, the mechanisms by which moxibustion may work include temperature-related and nontemperature-related ones. Local somatothermal stimulation (LSTS), one type of moxibustion, is achieved by application of a heat source to and above the acupoint. Such mild heat stimulation of the acupoint induces little skin damage, in contrast to the burning effect of moxibustion, but does provoke mild oxidative stress in the viscera. Thus, preconditioned LSTS at the peripheral acupoints LR 14 and PC 6 of animals is able to induce visceral HSP70 expression and to protect the liver and the heart against ischemia-reperfusion injury. Nontemperature-related mechanisms include smoke, herbs, and biophysical (far infrared) stimulation. We conclude that LSTS, a remote preconditioning method, has potential clinical usefulness. However, evidence-based efficacy and safety studies involving large-scaled clinical trials are needed in order that this approach will pass muster with Western scientists.

Remifentanil protects liver against ischemia/reperfusion injury through activation of anti-apoptotic pathways

BACKGROUND

Remifentanil protects against ischemia/reperfusion (I/R)-induced organ injury, although its underlying mechanism remains elusive. This study was designed to examine the protective effect of remifentanil preconditioning, if any, against hepatic I/R injury in rats and the underlying mechanism involved.

MATERIALS AND METHODS

Adult Sprague-Dawley rats were randomly divided into sham operation (S group), ischemia/reperfusion (I/R group), and remifentanil preconditioning (R group) groups. Rats in the I/R group were subjected to a partial (70%) hepatic ischemia for 45 min, followed by 1 h, 3 h, and 6 h of reperfusion. Rats in the R group received venous injection of remifentanil (2 μg/kg/min) from 30 min prior to hepatic ischemia to the end of ischemia. Hepatic morphology and apoptosis were examined. Markers of liver damage, oxidative stress, and inflammation were evaluated. Mitochondrial function was assessed using mitochondrial membrane potential and appearance of mitochondrial swelling.

RESULTS

Compared with the S group, rats in the I/R group displayed a massive degenerative death in liver tissues and significantly enhanced cell apoptosis. Remifentanil preconditioning significantly reduced I/R-induced hepatocyte apoptosis. In addition, remifentanil protected against I/R-induced mitochondrial swelling and loss of membrane potential. Remifentanil preconditioning inhibited I/R-induced increases in tumor necrosis factor α, intercellular adhesion molecule 1, and nuclear factor κB p65 levels in liver tissues. Remifentanil preconditioning also inhibited the loss in superoxide dismutase and rise in malondialdehyde levels in liver tissues going through I/R injury.

CONCLUSIONS

Our data revealed that remifentanil preconditioning may turn on multiple cellular pathways in hepatocytes to protect the liver from I/R injury by alleviating hepatic apoptosis.

New hepatectomy-induced postoperative adhesion model in rats, and evaluation of the efficacy of anti-adhesion materials

PURPOSE

Repeated hepatic resections are not uncommon during the surgical management of liver tumors. Postoperative adhesions induced by hepatectomies can have a significant negative impact on subsequent surgeries. We recently developed a new hepatectomy-induced postoperative adhesion animal model to evaluate the anti-adhesion efficacy of commercially available sheet materials (Seprafilm(®) and Interceed(®)) and the recently reported hyaluronan-based in situ cross-linkable hydrogels.

METHODS

The median lobe (ML) and the left lateral lobe (LLL) of the liver (approximately 70 % of the total liver) of 43 male Sprague-Dawley rats were resected based on the classical procedure; anti-adhesion materials were then applied. A relaparotomy was performed 1 week later to evaluate the adhesions and histopathological findings.

RESULTS

The rats without the application of anti-adhesion materials (n = 14) showed the most severe adhesions (grade 3) between the cut surface of the liver and the small bowel or omentum. All the barrier materials produced slight anti-adhesion effects. Adhesions between the liver surface and the diaphragm and adhesions around the hepatic hilum were less severe, but were not remarkably reduced, by the anti-adhesion materials.

CONCLUSION

We successfully established a new hepatectomy-induced animal adhesion model, which may be useful for the development of new anti-adhesion materials.

Assessment of effects of IR and IPC on activities of cytochrome P450 isozymes in rats by a five-drug cocktail approach

BACKGROUND AND OBJECTIVE

To evaluate the effects of ischemia and reperfusion (IR) and ischemic preconditioning (IPC) on the metabolic activities of cytochrome P450 (CYP) isozymes in rats by a five-drug cocktail approach.

METHODS

Cocktail approach was used to evaluate the influence of IR and IPC on the activities of CYP1A2, CYP2C9, CYP2E1, CYP2D6 and CYP3A4, which were reflected by the changes of pharmacokinetic parameters of five specific probe drugs: caffeine, chlorzoxazone, tolbutamide, metoprolol and midazolam, respectively. Rats were randomly divided into IR, IPC and sham groups, and then injected the mixture of five probe drugs. Blood samples were collected at a series of time-points and the concentrations of probe drugs in plasma were determined by a HPLC method with UV detection. The pharmacokinetic parameters were calculated by the software of DAS 2.0.

RESULTS

The parameters including t(1/2β), CLs, AUC, MRT and K10 exhibited a similar tendency for both IR and IPC groups. Compared with sham group, CLs and K10 of five probe drugs were significantly lower (p < 0.05), AUC and t(1/2β) of five or some probe drugs were significantly increased in IR and IPC groups (p < 0.05). Compared with IPC group, CLs of five probe drugs were decreased and AUC were significantly increased in the IR group (p < 0.05).

CONCLUSION

IR can variably decrease the activities of CYP isozymes in rats and this decrease can be attenuated by IPC.

Adaptive response, evidence of cross-resistance and its potential clinical use

Organisms and their cells are constantly exposed to environmental fluctuations. Among them are stressors, which can induce macromolecular damage that exceeds a set threshold, independent of the underlying cause. Stress responses are mechanisms used by organisms to adapt to and overcome stress stimuli. Different stressors or different intensities of stress trigger different cellular responses, namely induce cell repair mechanisms, induce cell responses that result in temporary adaptation to some stressors, induce autophagy or trigger cell death. Studies have reported life-prolonging effects of a wide variety of so-called stressors, such as oxidants, heat shock, some phytochemicals, ischemia, exercise and dietary energy restriction, hypergravity, etc. These stress responses, which result in enhanced defense and repair and even cross-resistance against multiple stressors, may have clinical use and will be discussed, while the emphasis will be on the effects/cross-effects of oxidants.