Activated Kupffer cells cause a hypermetabolic state after gentle in situ manipulation of liver in rats

SHMT2 Promotes Liver Regeneration Through Glycine-activated Akt/mTOR Pathway

BACKGROUND

The development of liver transplantation (LT) is increasingly being limited by the unavailability of liver grafts. Unique regenerative capacity of liver in response to injuries makes living-donor liver transplantation (LDLT) a feasible strategy to meet clinical demands. Serine hydroxymethyl-transferase 2 (SHMT2) serves as the key enzyme in the biosynthesis of glycine. Glycine affects the activity of mammalian target of rapamycin (mTOR), which is important for cellular growth and proliferation. In this study, the effects of SHMT2 on mouse liver regeneration were investigated using a classical partial hepatectomy (PH) model.

METHODS

In vivo, PH was performed on mice with or without knockdown of SHMT2. In vitro, SHMT2 was overexpressed in primary hepatocytes, which were cultured in customized Dulbecco's modified eagle media and LY294002 (an Akt inhibitor). Relevant indexes of liver regeneration, cell proliferation, and Akt/mTOR signal pathways were analyzed.

RESULTS

After PH, the expression levels of SHMT2 fluctuated with time and knockdown of SHMT2 in vivo lowered the regenerative ability of liver, with reduced glycine levels compared to the scramble group. In addition, overexpression of SHMT2 in hepatocytes boosted glycine production while enhancing Akt/mTOR pathway activity. These results were validated by the application of LY294002 in vitro.

CONCLUSIONS

SHMT2 can contribute to liver regeneration after PH, and this is likely related to the activation of Akt/mTOR signaling pathway by its metabolic product, glycine, in hepatocytes. These results might have therapeutic implications for the prognosis of patients undergoing hepatic resection or transplantation.

Improvement of Normothermic Ex Vivo Machine Perfusion of Rat Liver Grafts by Dialysis and Kupffer Cell Inhibition With Glycine

Normothermic ex vivo liver machine perfusion might be a superior preservation strategy for liver grafts from extended criteria donors. However, standardized small animal models are not available for basic research on machine perfusion of liver grafts. A laboratory-scaled perfusion system was developed consisting of a custom-made perfusion chamber, a pressure-controlled roller pump, and an oxygenator. Male Wistar rat livers were perfused via the portal vein for 6 hours using oxygenated culture medium supplemented with rat erythrocytes. A separate circuit was connected via a dialysis membrane to the main circuit for plasma volume expansion. Glycine was added to the flush solution, the perfusate, and the perfusion circuit. Portal pressure and transaminase release were stable over the perfusion period. Dialysis significantly decreased the potassium concentration of the perfusate and led to significantly higher bile and total urea production. Hematoxylin-eosin staining and immunostaining for single-stranded DNA and activated caspase 3 showed less sinusoidal dilatation and tissue damage in livers treated with dialysis and glycine. Although Kupffer cells were preserved, tumor necrosis factor α messenger RNA levels were significantly decreased by both treatments. For proof of concept, the optimized perfusion protocol was tested with donation after circulatory death (DCD) grafts, resulting in significantly lower transaminase release into the perfusate and preserved liver architecture compared with baseline perfusion. In conclusion, our laboratory-scaled normothermic portovenous ex vivo liver perfusion system enables rat liver preservation for 6 hours. Both dialysis and glycine treatment were shown to be synergistic for preservation of the integrity of normal and DCD liver grafts.

Control of Ischemia-Reperfusion Injury in Liver Transplantation: Potentials for Increasing the Donor Pool

Background

Organ shortage is a growing problem, with a rising number of organs being harvested from extended criteria donors, and this trend will further continue to increase as organ donors are getting older and have more comorbidities. Since this fact is immutable, efforts have been made to reduce the extent of ischemia-reperfusion injury (IRI) as well as of direct and indirect harvest-related graft injury which affects all organs in a more or less distinct way.

Methods

In liver transplantation (LT), the activation of Kupffer cells during organ reperfusion, thus provoking microcirculatory disturbances, hypoxia, and endothelial cell injury, is one of the key mechanisms causing graft dysfunction. Multiple approaches have been taken in order to find efficient preconditioning methods by pharmacological pretreatment, controlled induction of ischemia, controlled denervation of donor organs, and reconditioning with machine perfusion to prevent IRI, whereas marginal organs (i.e. steatotic grafts) are especially vulnerable.

Results

The above-mentioned approaches have been pursued in experimental and clinical settings. At this time point, however, there is not yet enough clinical evidence available to recommend any particular drug pretreatment or any other intervention for organ preconditioning prior to transplantation.

Conclusion

The multifactorial pathophysiology in the setting of IRI in LT requires a multimodal therapeutic approach with the integration of pharmacological and technical means being applied to the donor, the organ per se, and the recipient. Currently, there is no consensus on standardized pretreatment of donor organs in order to improve the transplant outcome.

Surgical issues in retrieval and implantation

With increasing demand for organ transplantation and patients deteriorating or dying on the waiting list, organs are now being increasingly used from donors previously considered too marginal. This requires improvements to donor management during the retrieval process, and of the organ during transport and subsequent implantation, in order to maintain outcomes.

Multifarious Beneficial Effect of Nonessential Amino Acid, Glycine: A Review

Glycine is most important and simple, nonessential amino acid in humans, animals, and many mammals. Generally, glycine is synthesized from choline, serine, hydroxyproline, and threonine through interorgan metabolism in which kidneys and liver are the primarily involved. Generally in common feeding conditions, glycine is not sufficiently synthesized in humans, animals, and birds. Glycine acts as precursor for several key metabolites of low molecular weight such as creatine, glutathione, haem, purines, and porphyrins. Glycine is very effective in improving the health and supports the growth and well-being of humans and animals. There are overwhelming reports supporting the role of supplementary glycine in prevention of many diseases and disorders including cancer. Dietary supplementation of proper dose of glycine is effectual in treating metabolic disorders in patients with cardiovascular diseases, several inflammatory diseases, obesity, cancers, and diabetes. Glycine also has the property to enhance the quality of sleep and neurological functions. In this review we will focus on the metabolism of glycine in humans and animals and the recent findings and advances about the beneficial effects and protection of glycine in different disease states.

Clinical outcomes and genetic expression profile in human liver graft dysfunction during ischemia/reperfusion injury

INTRODUCTION

This study aims to compare the molecular gene expression during ischemia reperfusion injury. Several surgical times were considered: in the beginning of the harvesting (T0), at the end of the cold ischemia period (T1), and after reperfusion (T2) and compared with graft dysfunction after liver transplant (OLT).

METHODS

We studied 54 patients undergoing OLT. Clinical, laboratory data, and histologic data (Suzuki classification) as well as the Survival Outcomes Following Liver Transplantation (SOFT) score were used and compared with the molecular gene expression of the following genes: Interleukin (IL)-1b, IL-6, tumor necrosis factor-α, perforin, E-selectin (SELE), Fas-ligand, granzyme B, heme oxygenase-1, and nitric oxide synthetase.

RESULTS

Fifteen patients presented with graft dysfunction according to SOFT criteria. No relevant data were obtained by comparing the variables graft dysfunction and histologic variables. We observed a statistically significant relation between SELE at T0 (P = .013) and IL-1β at T0 (P = .028) and early graft dysfunction.

CONCLUSIONS

We conclude that several genetically determined proinflammatory expressions may play a critical role in the development of graft dysfunction after OLT.

Long term intravital multiphoton microscopy imaging of immune cells in healthy and diseased liver using CXCR6.Gfp reporter mice

Liver inflammation as a response to injury is a highly dynamic process involving the infiltration of distinct subtypes of leukocytes including monocytes, neutrophils, T cell subsets, B cells, natural killer (NK) and NKT cells. Intravital microscopy of the liver for monitoring immune cell migration is particularly challenging due to the high requirements regarding sample preparation and fixation, optical resolution and long-term animal survival. Yet, the dynamics of inflammatory processes as well as cellular interaction studies could provide critical information to better understand the initiation, progression and regression of inflammatory liver disease. Therefore, a highly sensitive and reliable method was established to study migration and cell-cell-interactions of different immune cells in mouse liver over long periods (about 6 hr) by intravital two-photon laser scanning microscopy (TPLSM) in combination with intensive care monitoring. The method provided includes a gentle preparation and stable fixation of the liver with minimal perturbation of the organ; long term intravital imaging using multicolor multiphoton microscopy with virtually no photobleaching or phototoxic effects over a time period of up to 6 hr, allowing tracking of specific leukocyte subsets; and stable imaging conditions due to extensive monitoring of mouse vital parameters and stabilization of circulation, temperature and gas exchange. To investigate lymphocyte migration upon liver inflammation CXCR6.gfp knock-in mice were subjected to intravital liver imaging under baseline conditions and after acute and chronic liver damage induced by intraperitoneal injection(s) of carbon tetrachloride (CCl4). CXCR6 is a chemokine receptor expressed on lymphocytes, mainly on Natural Killer T (NKT)-, Natural Killer (NK)- and subsets of T lymphocytes such as CD4 T cells but also mucosal associated invariant (MAIT) T cells1. Following the migratory pattern and positioning of CXCR6.gfp+ immune cells allowed a detailed insight into their altered behavior upon liver injury and therefore their potential involvement in disease progression.

Short- and long-term outcomes after laparoscopic and open hepatectomy for hepatocellular carcinoma: a global systematic review and meta-analysis

BACKGROUND

Laparoscopic hepatectomy (LH) has been proposed as a safe and feasible treatment option for liver diseases. However, the short- and long-term outcomes of LH versus open hepatectomy (OH) for hepatocellular carcinoma (HCC) have not been adequately assessed. Thus, as another means of surgical therapy for hepatocellular carcinoma (HCC), we assessed the feasibility of performing LH as the standard procedure for disease in the left lateral lobe and peripheral right segments for HCC in selected patients.

METHODS

Literature search included PubMed, Embase, Science Citation Index, SpringerLink, and secondary sources, from inception to March 2012, with no restrictions on languages or regions. The fixed-effects and random-effects models were used to measure the pooled estimates. The test of heterogeneity was performed by the Q statistic. Subgroup and sensitivity analyses were performed to explore heterogeneity between studies and to assess the effects of study quality.

RESULTS

A total of 1238 patients (LH 485, OH 753) from 15 studies were included. The pooled odds ratios for postoperative morbidity and incidence of negative surgical margin in LH were found to be 0.37 (95 % confidence interval [CI] 0.27-0.52; P < 0.01) and 1.63 (95 % CI 0.82-3.22; P = 0.16), respectively, compared with OH. Blood loss was significantly decreased in the LH (weighted mean difference -224.63; 95 % CI -384.87 to -64.39; P = 0.006). No significant difference was observed between the both groups for long-term outcomes of overall survival and recurrence-free survival.

CONCLUSIONS

In patients with solitary left lateral lobe/right peripheral subcapsular tumors treated with minor resection, this meta-analysis demonstrated that compared to OH, LH may have short-term advantages in terms of blood loss and postoperative morbidity for HCC. Both procedures have similar long-term outcomes. It may be time to consider changing the standard procedures for treatment of HCC in the left lateral lobe and peripheral subcapsular right segments in selected patients.

Hepatic cytokine response can be modulated using the Kupffer cell blocker gadolinium chloride in obstructive jaundice

INTRODUCTION

Depletion of Kupffer cells by gadolinium chloride (GdCl(3)) reduces the systemic response during sepsis. The study aim was to investigate the effect of this depletion on hepatic proinflammatory cytokine response to portal endotoxaemia.

METHODS

Sixteen Wistar rats were randomised to receive either saline IV (n = 8) or GdCl(3) (10 mg/kg IV, n = 8) six days after bile duct ligation (BDL). 24 h later the animals were perfused for 2 h, using isolated hepatic perfusion. Aliquots of effluent perfusate were collected at 20-min intervals for cytokine analysis. Sections of liver were sampled and the hepatic Kupffer cell number of each group was measured using ED1 immunohistochemistry.

RESULTS

Pre-treatment with GdCl(3) resulted in significantly reduced serum bilirubin concentrations but significantly elevated serum ALP and AST levels compared to the control group. It was also associated with a significant reduction in Kupffer cell numbers and a corresponding significant reduction in hepatic TNFα and IL-6 production in response to portal endotoxaemia.

CONCLUSIONS

Pre-treatment with GdCl(3) in jaundiced animals reduced Kupffer cell numbers, attenuated liver enzyme abnormalities and reduced TNFα and IL-6 in response to portal endotoxaemia. Hepatic Kupffer cells, therefore, play a significant role in the development of an exaggerated inflammatory response in obstructive jaundice.

HTK-N, a modified HTK solution, decreases preservation injury in a model of microsteatotic rat liver transplantation

BACKGROUND

Ischemia/reperfusion injury is an obstacle especially in steatotic livers, including those with steatosis induced by acute toxic stress. Recently, a modified histidine-tryptophan-ketoglutarate (HTK) solution, HTK-N, has been developed. This solution contains N-acetylhistidine, amino acids, and iron chelators. This study was designed to test the effects of HTK-N on preservation injury to rat livers after acute toxic injury.

METHODS

Microvesicular steatosis was induced by a single dose of ethanol (8 g/kg BW). Livers were harvested and stored at 4 °C for 8 h with HTK or HTK-N before transplantation. Tissue and blood samples were taken at 1, 8, and 24 h after reperfusion to compare serum liver enzymes (aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase), standard histology, and immunohistochemistry for myeloperoxidase (MPO), caspase-3, and inducible nitric oxide synthase. Survival was compared after 1 week. For statistics, Analysis of Variance and t test were used.

RESULTS

HTK-N improved survival from 12.5% in HTK to 87.5% (p < 0.05). Furthermore, liver enzymes were decreased to 2-75% of HTK values (p < 0.05). Necrosis and leukocyte infiltration and MPO, caspase-3, and iNOS expression after transplantation were decreased (p < 0.05).

CONCLUSIONS

This study demonstrates that HTK-N protects liver grafts with microvesicular steatosis caused by acute toxic injury from cold ischemic injury better than standard HTK most likely via inhibition of hypoxic injury and oxidative stress and amelioration of the inflammatory reaction occurring upon reperfusion.

Albendazole and colchicine modulate LPS-induced secretion of inflammatory mediators by liver macrophages

Colchicine and albendazole inhibited LPS-induced secretion of TNF-α and NO in a primary culture of rat Kupffer cells. Both agents potentiated the stimulating effect of this toxin on prostaglandin E2 secretion. The amount of prostaglandin D2 remained unchanged under these conditions.

Glycine, a simple physiological compound protecting by yet puzzling mechanism(s) against ischaemia-reperfusion injury: current knowledge

Ischaemia is amongst the leading causes of death. Despite this importance, there are only a few therapeutic approaches to protect from ischaemia-reperfusion injury (IRI). In experimental studies, the amino acid glycine effectively protected from IRI. In the prevention of IRI by glycine in cells and isolated perfused or cold-stored organs (tissues), direct cytoprotection plays a crucial role, most likely by prevention of the formation of pathological plasma membrane pores. Under in vivo conditions, the mechanism of protection by glycine is less clear, partly due to the physiological presence of the amino acid. Here, inhibition of the inflammatory response in the injured tissue is considered to contribute decisively to the glycine-induced reduction of IRI. However, attenuation of IRI recently achieved in experimental animals by low-dose glycine treatment regimens suggests additional/other (unknown) protective mechanisms. Despite the convincing experimental evidence and the large therapeutic width of glycine, there are only a few clinical trials on the protection from IRI by glycine with ambivalent results. Thus, both the mechanism(s) behind the protection of glycine against IRI in vivo and its true clinical potential remain to be addressed in future experimental studies/clinical trials.

Effects of a preconditioning oral nutritional supplement on pig livers after warm ischemia

Background. Several approaches have been proposed to pharmacologically ameliorate hepatic ischemia/reperfusion injury (IRI). This study was designed to evaluate the effects of a preconditioning oral nutritional supplement (pONS) containing glutamine, antioxidants, and green tea extract on hepatic warm IRI in pigs. Methods. pONS (70 g per serving, Fresenius Kabi, Germany) was dissolved in 250 mL tap water and given to pigs 24, 12, and 2 hrs before warm ischemia of the liver. A fourth dose was given 3 hrs after reperfusion. Controls were given the same amount of cellulose with the same volume of water. Two hours after the third dose of pONS, both the portal vein and the hepatic artery were clamped for 40 min. 0.5, 3, 6, and 8 hrs after reperfusion, heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), portal venous flow (PVF), hepatic arterial flow (HAF), bile flow, and transaminases were measured. Liver tissue was taken 8 hrs after reperfusion for histology and immunohistochemistry. Results. HR, MAP, CVP, HAF, and PVF were comparable between the two groups. pONS significantly increased bile flow 8 hrs after reperfusion. ALT and AST were significantly lower after pONS. Histology showed significantly more severe necrosis and neutrophil infiltration in controls. pONS significantly decreased the index of immunohistochemical expression for TNF-α, MPO, and cleaved caspase-3 (P < 0.001). Conclusion. Administration of pONS before and after tissue damage protects the liver from warm IRI via mechanisms including decreasing oxidative stress, lipid peroxidation, apoptosis, and necrosis.

Small-for-Size Liver Transplantation Increases Pulmonary Injury in Rats: Prevention by NIM811

Pulmonary complications after liver transplantation (LT) often cause mortality. This study investigated whether small-for-size LT increases acute pulmonary injury and whether NIM811 which improves small-for-size liver graft survival attenuates LT-associated lung injury. Rat livers were reduced to 50% of original size, stored in UW-solution with and without NIM811 (5 μM) for 6 h, and implanted into recipients of the same or about twice the donor weight, resulting in half-size (HSG) and quarter-size grafts (QSG), respectively. Liver injury increased and regeneration was suppressed after QSG transplantation as expected. NIM811 blunted these alterations >75%. Pulmonary histological alterations were minimal at 5–18 h after LT. At 38 h, neutrophils and monocytes/macrophage infiltration, alveolar space exudation, alveolar septal thickening, oxidative/nitrosative protein adduct formation, and alveolar epithelial cell/capillary endothelial apoptosis became overt in the lungs of QSG recipients, but these alterations were mild in full-size and HSG recipients. Liver pretreatment with NIM811 markedly decreased pulmonary injury in QSG recipients. Hepatic TNFα and IL-1β mRNAs and pulmonary ICAM-1 expression were markedly higher after QSG transplantation, which were all decreased by NIM811. Together, dysfunctional small-for-size grafts produce toxic cytokines, leading to lung inflammation and injury. NIM811 decreased toxic cytokine formation, thus attenuating pulmonary injury after small-for-size LT.

Assessment of a chloride-poor versus a chloride-containing version of a modified histidine-tryptophan-ketoglutarate solution in a rat liver transplantation model

Recent in vitro studies of cold-induced cell injury have revealed the detrimental effects of extracellular chloride on cold-stored isolated rat hepatocytes; however, its influence on endothelial cells is beneficial. To determine which of these effects is predominant in vivo, we tested both a chloride-poor variant of a new histidine-tryptophan-ketoglutarate (HTK)-based preservation solution and a chloride-containing variant in a rat liver transplantation model. The study, which was carried out in a blinded fashion with 7 or 8 rats per group, was divided into 2 parts: (1) a comparison of survival in 3 series under different conditions [different microsurgeons, rat strains, cold ischemia times (3, 12, and 24 hours), and warm ischemia times] and (2) an assessment of the microcirculation (30-90 minutes after reperfusion), laboratory data, bile production, and histology. In each of the survival experiments, a (strong) tendency toward prolonged survival was observed with the new chloride-containing solution (50% versus 12.5%, 75% versus 37.5%, and 100% versus 71.4% [chloride-containing vs. chloride-poor], overall P < 0.05). Additionally, the sinusoidal perfusion rates (83.9% ± 4.0% versus 69.2% ± 10.8%, P < 0.01) and the red blood cell velocities in sinusoids (147.7 ± 26.7 versus 115.5 ± 26.0 μm/second, P < 0.05) and in postsinusoidal venules (332.4 ± 87.3 versus 205.5 ± 53.5 μm/second, P < 0.01) were clearly higher with chloride. Moreover, the serum activities of liver enzymes were slightly reduced (not significantly), and bile production was significantly increased. These results suggest an overall beneficial effect of chloride in HTK-based liver preservation solutions.

HMGB1 translocation and expression is caused by warm ischemia reperfusion injury, but not by partial hepatectomy in rats

Mechanical injury or ischemia/reperfusion (I/R) injury induces high mobility of group box 1 (HMGB1) translocation and release. However, the surgical procedure itself can initiate pathophysiologic processes causing damage to the respective organ. A liver resection, as an example, leads to portal hyperperfusion injury of the remnant liver. Therefore, we aimed to elucidate the impact of different hepatic surgical injury models on cellular localization and expression of HMGB1. Focal warm I/R injury was induced by clamping the vascular blood supply to the median and left lateral liver lobes for 90 min followed by 0.5 h, 6 h and 24 h reperfusion, as reported previously. Liver injury by PH was induced by subjecting rats to 30%, 70% or 90% partial hepatectomy (PH) followed by a 24 h observation period. Additional 12 rats were subjected to 90% PH and sacrificed at 1 h and 6 h to investigate the expression and release pattern of HMGB1. Elevation of serum liver enzymes indicating hepatic injury peaked at 6 h and recovered thereafter in models, warm I/R injury and PH. Liver injury was confirmed by liver histology. HMGB1 was translocated from the nucleus to the cytoplasm in livers subjected to warm I/R; but not in livers subjected to PH. Both protein and mRNA expression of HMGB1 were significantly up-regulated in livers subjected to warm I/R. In contrast, neither 30% PH, 70% PH nor 90% PH caused an elevation of hepatic HMGB1 mRNA and protein expression. High serum levels of HMGB1 (30 ng/ml) were measured at 0.5 h reperfusion period after warm I/R, much lower levels thereafter (<5 ng/ml). Similar low serum levels were measured at all time points after 90% PH. Subsequently expression levels of TNF-a should be changed to tumor necrosis factor-alpha (TNF-α) reached a peak (26-fold elevation) at 6 h and decreased down to 5-fold at 24 h after warm I/R. TNF-α expression levels after PH never exceeded a 5-fold elevation. In conclusion, HMGB1 translocation and expression depends on the type of liver injury as it is induced by ischemia, but not by liver resection/hyperperfusion. These results suggest that HMGB1 may be used as molecular marker to visualize ischemic damage. Mechanic injury in hepatic surgery is associated with focal warm ischemia, and thereby HMGB1 translocation reflects surgical quality in experimental PH. Expression of hepatic TNF-α follows the kinetic pattern of HMGB1, pointing to a muss less pronounced inflammatory response after successful PH compared to warm I/R injury.

Green tea extract ameliorates reperfusion injury to rat livers after warm ischemia in a dose-dependent manner

SCOPE

Polyphenolic constituents of green tea (Camellia sinensis) have been shown to be potent scavengers of reactive oxygen species (ROS). Thus, this study was designed to assess its effects after liver ischemia-reperfusion.

METHODS AND RESULTS

Fasted Sprague-Dawley rats were gavaged with different concentrations of green tea extract (GTE) 2 h before 90 min of warm ischemia of the left lateral liver lobe (30% of liver). Controls were given the same volume of Ringer's solution. A preparation of pentobarbital sodium (intraperitoneal) and ketamine (intramuscular) was used for anesthesia. After reperfusion, transaminases, liver histology, hepatic microcirculation, and both phagocytosis of latex bead particles as well as the expression of tumor necrosis alpha (TNF-α) to index cellular activation were investigated. Furthermore, the expression of superoxide dismutase (Mn-SOD) was assessed. After 90 min of warm ischemia aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) increased dramatically to 1946 ± 272/3244 ± 757 U/L, 1680 ± 134/2080 ± 379 U/L, and 7857 ± 1851/2036 ± 1193 U/L at 2/6 h, respectively. GTE (200 mg/kgbody weight) significantly prevented this increase in a dose-dependent manner by 21-51% at 2 h and 29-34% at 6 h, respectively. Histology confirmed the protective effects while both TNF-α expression and phagocytosis of latex beads by Kupffer cells (KCs) were significantly reduced. GTE intake significantly increased the expression of manganese superoxide dismutase. In vivo microscopy revealed improved acinar and sinusoidal perfusion after GTE.

CONCLUSION

Preconditioning with a single oral dose of GTE ameliorates ischemia-reperfusion injury in liver. Decreased cellular activation and improved microcirculation are the proposed mechanisms.

The use of high-dose melatonin in liver resection is safe: first clinical experience

Experimental data suggest that melatonin decreases inflammatory changes after major liver resection, thus positively influencing the postoperative course. To assess the safety of a preoperative single dose of melatonin in patients undergoing major liver resection, a randomized controlled double-blind pilot clinical trial with two parallel study arms was designed at the Department of General and Transplantation Surgery, Ruprecht-Karls-University, Heidelberg. A total of 307 patients, who were referred for liver surgery, were screened. One hundred and thirteen patients, for whom a major liver resection (≥3 segments) was scheduled, were eligible. Sixty-three eligible patients refused to participate, and therefore, 50 patients were randomized. A preoperative single dose of melatonin (50 mg/kg BW) dissolved in 250 mL of milk was administered through the gastric tube after the intubation for general anesthesia. Controls were given the same amount of microcrystalline cellulose. Primary endpoint was safety. Secondary endpoints were postoperative complications. Melatonin was effectively absorbed with serum concentrations of 1142.8 ± 7.2 ng/mL (mean ± S.E.M.) versus 0.3 ± 7.8 ng/mL in controls (P < 0.0001). Melatonin treatment resulted in lower postoperative transaminases over the study period (P = 0.6). There was no serious adverse event in patients after melatonin treatment. A total of three infectious complications occurred in either group. A total of eight noninfectious complications occurred in five control patients, whereas three noninfectious complications occurred in three patients receiving preoperative melatonin (P = 0.3). There was a trend toward shorter ICU stay and total hospital stay after melatonin treatment. Therefore, a single preoperative enteral dose of melatonin is effectively absorbed and is safe and well tolerated in patients undergoing major liver surgery.

Split-liver procedure and inflammatory response: improvement by pharmacological preconditioning

BACKGROUND

Final outcome of split-liver (SL) transplantation is impaired due to an increased rate of vascular complications and primary non-function. Herein, we hypothesized that an in situ split-liver procedure induces an inflammatory response and a deterioration of graft quality. We further studied whether graft quality can be improved by pharmacologic preconditioning.

MATERIAL AND METHODS

SL-procedure was performed in rats. One group (SL-HPP; n = 8) was pretreated according to a defined protocol [Homburg preconditioning protocol (HPP)], including pentoxyphylline, glycine, deferoxamine, N-acetylcysteine, erythropoietin, melatonin, and simvastatin. A second SL group (SL-Con; n = 8) received NaCl. Untreated non-SL served as controls (Sham; n = 8). Cytokines release, leukocyte invasion, endothelial activation and liver morphology were studied directly after liver harvest and after 8 h cold storage. Lung tissue was studied to determine remote injury.

RESULTS

The SL-procedure induced an increase of TNF-α concentration, intercellular-adhesion-molecule 1 (ICAM-1) expression, leukocytic-tissue infiltration and vacuolization. This was associated with an increased number of apoptotic hepatocytes. HPP reduced TNF-α release, ICAM-1 expression, the number of infiltrated leukocytes, as well as hepatocellular vacuolization and apoptosis. In lung tissue, the SL-procedure caused an increased IL-1 and IL-6 concentration and leukocyte infiltration.

CONCLUSIONS

HPP was capable of abrogating cytokine-mediated leukocytic response. Pharmacologic preconditioning of liver donors prevents the SL procedure-mediated inflammatory response, resulting in an improved graft quality.

Anti-inflammatory role of glycine in reducing rodent postoperative inflammatory ileus

BACKGROUND

Inflammatory events within the intestinal muscularis, including macrophage activation and leukocyte recruitment, have been demonstrated to participate in causing postoperative ileus. Recently, glycine has gained attention due to its beneficial immunomodulatory effects in transplantation, shock and sepsis.

METHODS

Muscularis glycine receptors were investigated by immunohistochemistry. Gastrointestinal motility was assessed by in vivo transit distribution histograms with calculated geometric center analysis and jejunal circular smooth muscle contractility in a standard organ bath. The impact of glycine on the muscularis inflammatory responses to surgical manipulation of the intestine were measured by real-time PCR, nitric oxide Griess reaction, prostaglandin ELISA, Luminex and histochemistry.

KEY RESULTS

Glycine-gated chloride channels were immunohistochemically localized to muscularis macrophages and postoperative infiltrating leukocytes. Preoperative glycine treatment significantly improved postoperative gastrointestinal transit and jejunal circular muscle contractility. Preoperative glycine injection significantly reduced the induction of interleukin-6 (IL-6), tumor necrosis factor-α, inducible nitric oxide synthase and intercellular adhesion molecule-1 mRNAs, which was associated with the attenuation in postoperative leukocyte recruitment. Nitric oxide and prostanoid release from the postsurgical inflamed muscularis was diminished by glycine. The secretion of the inflammatory proteins IL-6, monocyte chemotactic protein-1/chemokine ligand 2 and macrophage inflammatory protein-1α/chemokine ligand 3 were also significantly decreased by glycine pretreatment.

CONCLUSIONS & INFERENCES

The data indicate that preoperative glycine reduces postoperative ileus via the early attenuation of primal inflammatory events within the surgically manipulated gut wall. Therapeutic modulation of resident macrophages by glycine is a potential novel pharmacological target for the prevention of postoperative ileus.

Melatonin protects from hepatic reperfusion injury through inhibition of IKK and JNK pathways and modification of cell proliferation

Reactive oxygen species (ROS) are involved in pathophysiology of ischemia/reperfusion injury. Melatonin is a potent scavenger of ROS. Thus, this study was designed to elucidate its effects in a combined hepatic warm ischemia and resection model. The right lateral and caudate lobes (32% of liver volume) of Sprague-Dawley rats underwent warm ischemia for 30 min followed by reperfusion and subsequent resection of the nonischemic liver tissue. Some rats were gavaged with 50 mg/kg melatonin 2 hr before the onset of experiments. Controls received the same volume of microcrystalline cellulose. Survival, transaminases, histology, flow cytometry, inducible nitric oxide synthase (iNOS) expression, and activation of signal transduction pathways [c-Jun N-terminal kinase (JNK), cJUN, IkappaB kinase alpha (IKKalpha), proliferating cell nuclear antigen (PCNA), and Ki67] were assessed for hepatic injury, oxidative stress, and cell proliferation. Melatonin significantly improved animal survival and decreased transaminase levels, the indices for necrosis, liver damage, leukocyte infiltration, and iNOS expression. In parallel, the expression of IKKalpha, JNK1, and cJUN decreased by 35-50% after melatonin (P < 0.05). At the same time, melatonin reduced the expression of both PCNA and Ki67 in liver (P < 0.05). Melatonin is hepatoprotective most likely via mechanisms including inhibition of IKK and JNK pathways and regulation of cell proliferation.

Danshen protects kidney grafts from ischemia/reperfusion injury after experimental transplantation

Danshen (DS) is used for treatment of various ischemic events in the traditional Chinese medicine. Hence, this study was designed to investigate its effect on ischemia/reperfusion injury (IRI) after experimental kidney transplantation (eKTx). Nephrectomized Sprague-Dawley rats underwent eKTx. Some animals were infused with 1.5 ml DS 10 min before surgery. Kidney grafts were transplanted after cold storage for 20 h in Histidine-Tryptophane-Ketoglutarate solution. After reperfusion blood samples were collected for blood urinary nitrogen (BUN), creatinine, lactate dehydrogenase (LDH), and alanine transaminase. Further, tissue was assessed for morphologic and pathophysiologic changes. Donor preconditioning with DS (DS-d) significantly decreased BUN, creatinine, LDH, and aspartate aminotransferase to 65-97% of controls while preconditioning of the recipient (DS-r) decreased values to 58-82% (P < 0.05). Tubular damage and caspase-3 decreased significantly in both DS-d and DS-r (DS-d: 96% and 67%, DS-r: 83% and 75% of controls) while heat shock protein 72 and superoxide dismutase increased significantly (DS-d: 143% and 173%, DS-r: 166% and 194% of controls). Further, inducible nitric oxide synthase and tumor necrosis factor-alpha decreased (DS-d: 84% and 61%, DS-r: 79% and 67% of controls) after DS. Preconditioning of both donors and recipients with DS significantly reduces IRI and thus improves graft function after eKTx.

Perioperative glycine treatment attenuates ischemia/reperfusion injury and ameliorates smooth muscle dysfunction in intestinal transplantation

BACKGROUND

Ischemia/reperfusion evokes a functionally relevant inflammatory response within the muscularis propria of small bowel grafts by activation of resident macrophages and leukocyte recruitment. We hypothesized that immunomodulatory perioperative treatment with glycine attenuates the proinflammatory cascade and improves smooth muscle dysfunction of small bowel grafts.

METHODS

Orthotopic SBTx was performed in Lewis rats. Glycine (1 mg/g body weight) was infused (0.1 mL/g/hr) for 2 hr before harvest as preconditioning in the donor, and for 2 hr from the onset of reperfusion in the recipient. Transplanted vehicle (isotonic saline)-treated animals and naive animals served as controls. Rats were sacrificed after 3 hr and 24 hr. Leukocyte infiltration was investigated in muscularis whole mounts by immunohistochemistry. Mediator mRNA expression was determined by real-time-PCR. Jejunal circular smooth muscle contractility was assessed in a standard organ bath.

RESULTS

Compared with vehicle controls, glycine-treated graft muscularis expressed a significant alleviation in mRNA peak expression for IL-6, IL-1beta, ICAM-1, MCP-1, TNFalpha, COX-2, and iNOS. Also glycine-treated grafts exhibited significantly less infiltration with ED-1-positive macrophages and MPO-positive neutrophils as well as reduced apoptosis. Concurrent to these results, vehicle controls showed an 80% decrease in smooth muscle contractility, whereas glycine-treated animals exhibited only a 40% decrease in contractile activity compared with controls.

CONCLUSIONS

The data indicate that perioperative glycine treatment reduces the molecular and cellular inflammatory response within the grafts and improves smooth muscle dysfunction after transplantation. Therefore, the glycine-activated chloride channel on resident and infiltrating leukocytes could be a promising pharmacologic target to attenuate ischemia/reperfusion injury after ITx.

Influence of approach on outcome in radiofrequency ablation of liver tumors

In this article some recent data concerning the approach on radiofrequency ablation (RFA) of liver tumors are reviewed. Specifically, several critical statements between surgical and percutaneous approach are raised and discussed: (1) Open approach may lead to a higher complication rate; (2) Temporary occlusion of hepatic inflow during surgical approach may lead to a higher rate of ablation of the liver tumors; (3) Surgical approach may permit better targeting of the tumor to be ablated. (4) Surgical approach may discover additional liver tumors. Finally, several conclusions and recommendations are also addressed.

PORTAL: pilot study on the safety and tolerance of preoperative melatonin application in patients undergoing major liver resection: a double-blind randomized placebo-controlled trial

Background

Major surgical procedures facilitate systemic endotoxinemia and formation of free radicals with subsequent inflammatory changes that can influence the postoperative course. Experimental data suggest that preoperative supraphysiological doses of melatonin, a potent immuno-modulator and antioxidant, would decrease postoperative infectious and non-infectious complications induced by major abdominal surgery.

Methods/Design

A randomized controlled double blind single center clinical trial with two study arms comprising a total of 40 patients has been designed to assess the effects of a single preoperative dose of melatonin before major liver resection. Primary endpoints include the determination of safety and tolerance of the regimen as well as clinical parameters reflecting pathophysiological functions of the liver. Furthermore, data on clinical outcome (infectious and non-infectious complications) will be collected as secondary endpoints to allow a power calculation for a randomized clinical trial aiming at clinical efficacy.

Discussion

Based on experimental data, this ongoing clinical trial represents an advanced element of the research chain from bench to bedside in order to reach the highest level of evidence-based clinical facts to determine if melatonin can improve the general outcome after liver resection.

Trial Registration

EudraCT200600530815

Liver manipulation causes hepatocyte injury and precedes systemic inflammation in patients undergoing liver resection

Background

Liver failure following liver surgery is caused by an insufficient functioning remnant cell mass. This can be due to insufficient liver volume and can be aggravated by additional cell death during or after surgery. The aim of this study was to elucidate the causes of hepatocellular injury in patients undergoing liver resection.

Methods

Markers of hepatocyte injury (AST, GSTα, and L-FABP) and inflammation (IL-6) were measured in plasma of patients undergoing liver resection with and without intermittent inflow occlusion. To study the separate involvement of the intestines and the liver in systemic L-FABP release, arteriovenous concentration differences for L-FABP were measured.

Results

During liver manipulation, liver injury markers increased significantly. Arterial plasma levels and transhepatic and transintestinal concentration gradients of L-FABP indicated that this increase was exclusively due to hepatic and not due to intestinal release. Intermittent hepatic inflow occlusion, anesthesia, and liver transection did not further enhance arterial L-FABP and GSTα levels. Hepatocyte injury was followed by an inflammatory response.

Conclusions

This study shows that liver manipulation is a leading cause of hepatocyte injury during liver surgery. A potential causal relation between liver manipulation and systemic inflammation remains to be established; but since the inflammatory response is apparently initiated early during major abdominal surgery, interventions aimed at reducing postoperative inflammation and related complications should be started early during surgery or beforehand.

Signs of reperfusion injury following CO2 pneumoperitoneum: an in vivo microscopy study

BACKGROUND

During laparoscopic surgery, pneumoperitoneum is generally established by means of carbon dioxide (CO(2)) insufflation which may disturb hepatic microperfusion. It has been suggested that the desufflation at the end of the procedure creates a model of reperfusion in a previously ischemic liver, thus predisposing it to reperfusion injury.

METHODS

To study the effects of pneumoperitoneum on hepatic microcirculation, Sprague-Dawley rats underwent pneumoperitoneum with an intraabdominal pressure of 8 or 12 mmHg for 90 min. Subsequently, in vivo microscopy was performed to assess intrahepatic microcirculation and transaminases were measured to index liver injury.

RESULTS

A CO(2) pneumoperitoneum of 8 mmHg did not change serum transaminases; however, further increase of intraperitoneal pressure to 12 mmHg significantly increased AST, ALT, and LDH measured after desufflation to almost 1.5 times as much as control values of 49 +/- 5 U/L, 31 +/- 3 U/L, and 114 +/- 12 U/L. In parallel, in all subacinar zones the permanent adherence of both leukocytes and platelets to the endothelium increased by about sixfold and threefold, respectively. Furthermore, Kupffer cells labeled with latex beads as an index for their activation were significantly increased compared to controls.

CONCLUSION

This in vivo observation demonstrated traces of reperfusion injury in liver induced by the insufflation and desufflation of CO(2 )pneumoperitoneum. The clinical relevance of this finding and the issue of using hepatoprotective substances to prevent this injury should be further investigated.

Retrieval of abdominal organs for transplantation

BACKGROUND

Organ retrieval and donor management are not yet standardized. Different transplant centres apply various techniques, such as single or dual organ perfusion, dissection in the cold or warm, and single or en bloc organ removal. These different approaches may cause inconvenience, especially when more than one organ retrieval team is involved.

METHODS

Cochrane Library, Medline and PubMed were searched for publications on multiorgan donor/donation, retrieval technique and procurement. Levels of evidence and grades of recommendation were evaluated based on current advice from the Oxford Centre for Evidence-Based Medicine.

RESULTS

Multiorgan donation itself does not compromise the outcome of individual organ transplants. Dissection of abdominal organs for transplantation is best performed after cold perfusion. Abdominal organs should be removed rapidly, en bloc, and separated during back-table dissection in the cold, particularly if pancreas or intestine is included. Perfusion itself should be carried out after single cannulation of the aorta with an increased pressure.

CONCLUSION

Although the literature on organ retrieval is extensive, the level of evidence provided is mainly low. Nevertheless, optimized donor treatment and organ retrieval should increase the number and quality of cadaveric donor organs and improve graft function and survival.

HEGPOL: randomized, placebo controlled, multicenter, double-blind clinical trial to investigate hepatoprotective effects of glycine in the postoperative phase of liver transplantation [ISRCTN69350312]

Background

Kupffer cell-dependent ischemia / reperfusion (I/R) injury after liver transplantation is still of high clinical relevance, as it is strongly associated with primary dysfunction and primary nonfunction of the graft. Glycine, a non-toxic, non-essential amino acid has been conclusively shown in various experiments to prevent both activation of Kupffer cells and reperfusion injury. Based on both experimental and preliminary clinical data this study protocol was designed to further evaluate the early effect of glycine after liver transplantation.

Methods / design

A prospective double-blinded randomized placebo-controlled multicenter study with two parallel groups in a total of 130 liver transplant recipients was designed to assess the effect of multiple intravenous doses of glycine after transplantation. Primary endpoints in hierarchical order are: peak levels of both aspartat-amino-transaminase (AST) and alanine-amino-transaminase (ALT) as surrogates for the progression of liver related injury, as well as both graft and patient survival up to 2 years after transplantation. Furthermore, the effect of glycine on cyclosporine A-induced nephrotoxicity is evaluated.

Discussion

The ongoing clinical trial represents an advanced element of the research chain, along which a scientific hypothesis has to go by, in order to reach the highest level of evidence; a randomized, prospective, controlled double-blinded clinical trial. If the data of this ongoing research project confirm prior findings, glycine would improve the general outcome after liver transplantation.

Gadolinium chloride-induced improvement of postischemic hepatic perfusion after warm ischemia is associated with reduced hepatic endothelin secretion

Selective Kupffer cell blockade by gadolinium chloride (GdCl(3)) pretreatment of liver donors previously proved to be effective in reducing ischemia/reperfusion injury in rat liver transplants. Physiological mechanisms of this effect have not been specified so far. Vasoactive peptides are involved in liver blood flow regulation. We tested the hypothesis, that hepatic hemodynamic effects of GdCl(3) pretreatment are mediated by intrahepatic endothelin-1 (ET) secretion in a standardized porcine model of warm liver ischemia and reperfusion. Standardized warm hepatic ischemia (45 min) was induced after laparotomy in intubation narcoses (ITN) by Pringle-maneuver in pigs (n = 12). Animals were either pretreated with GdCl(3) (20 mg/kg i.v.) or sodium chloride 0.9% (control group) in a randomized manner 24 h before investigation. Relaparotomy was performed at day 7. Before, during ischemia and until 6 h after liver reperfusion, transhepatic blood flow (portal venous + hepatic artery flow) was defined by ultrasonic flow probes and hepatic parenchymous microcirculation evaluated by implanted thermodiffusion electrodes. ET plasma concentrations were analyzed (commercial RIA) at all time points in the hepatic veins after selective canulation. GdCl(3) pretreatment of animals markedly improved hepatic macro- and microperfusion before and particularly after warm ischemia. Mean ET plasma concentrations in the hepatic vein were significantly lower before, 6 h and 7 days after ischemia, compared with controls. Kupffer cell destruction by GdCl(3) pretreatment improves hepatic micro- and macroperfusion after warm ischemia, thus indicating reduced ischemia/reperfusion injury. Documented reduction of postischemic liver blood flow impairment after GdCl(3) pretreatment could be mediated by a decreased hepatic ET secretion, as hemodynamic effects were associated with significantly reduced ET plasma levels in hepatic veins.

Lipid peroxidation during ischemia depends on ischemia time in warm ischemia and reperfusion of rat liver

Prolonged hepatic warm ischemia has been incriminated in oxidative stress after reperfusion. However, the magnitude of oxidative stress during ischemia has been controversial. The aims of the present study were to elucidate whether lipid peroxidation progressed during ischemia and to clarify whether oxidative stress during ischemia aggravated the oxidative damage after reperfusion. Rats were subjected to 30 to 120 min of 70% warm ischemia alone or followed by reperfusion for 60 min. Lipid peroxidation (LPO) was evaluated by amounts of phosphatidylcholine hydroperoxide (PC-OOH) and phosphatidylethanolamine hydroperoxide (PE-OOH) as primary LPO products. Total amounts of malondialdehyde and 4-hydroxy-2-nonenal (MDA + 4-HNE), degraded from hydroperoxides, were also determined. PC-OOH and PE-OOH significantly increased at 60 and 120 min ischemia with concomitant increase of oxidized glutathione. These hydroperoxides did not increase at 60 min reperfusion after 60 min ischemia, whereas they did increase at 60 min reperfusion after 120 min ischemia with deactivation of phospholipid hydroperoxide glutathione peroxidase and superoxide dismutase. The amount of MDA + 4-HNE exhibited similar changes, but the velocity of production dropped with ischemic time longer than 60 min. In conclusion, oxidative stress progressed during ischemia and triggered the oxidative injury after reperfusion. Secondary LPO products are less sensitive, especially during ischemia, which may cause possible underestimation and discrepancy.

New Insights into the Cellular and Molecular Mechanisms of Cold Storage Injury

Solid organ grafts, but also other biologic materials requiring storage for a few hours to a few days, are usually stored under hypothermic conditions. To decrease graft injury during cold storage, organ preservation solutions were developed many years ago. However, since then, modern biochemical and cell biologic methods have allowed further insights into the molecular and cellular mechanisms of cold storage injury, including further insights into alterations of the cellular ion homeostasis, the occurrence of a mitochondrial permeability transition, and the occurrence of free–radical-mediated hypothermic injury and cold-induced apoptosis. These new aspects of cold storage injury, which are not covered by preservation solutions in current clinical use and offer the potential for improvement of organ and tissue preservation, are presented here.

Can current technology be integrated to facilitate laparoscopic living donor hepatectomy?

BACKGROUND

Living donor hepatectomy (LDH) is a technically demanding procedure that is an alternative for providing livers for transplantation. Unlike liver resections for other pathology, LDH requires preservation of the major vessels and biliary tree. This study was performed to determine if current technology can be integrated to perform laparoscopic LDH.

METHODS

Six adult sheep underwent laparoscopic LDH of the left lateral segment under general anesthesia. Instruments utilized included standard dissecting instruments, ultrasound, ultrasonic dissectors, CUSA, the TissueLink Floating Ball, and endoscopic staplers.

RESULTS

LDH-harvested liver grafts were 44% of whole liver weight. Estimated blood loss was 300 cc. Warm ischemia time was 5-7 min. Grafts were delivered through 18-cm abdominal wounds. Major vessels and biliary anatomy were positively identified in the grafts.

CONCLUSIONS

Laparoscopic LDH can be performed with available technology. Theoretical advantages include reduced liver manipulation and smaller wound size.

L-Glycine: a novel antiinflammatory, immunomodulatory, and cytoprotective agent

PURPOSE OF REVIEW

In recent years, evidence has mounted in favor of the antiinflammatory, immunomodulatory and cytoprotective effects of the simplest amino acid L-glycine. This article will focus on the recent findings about the responsible mechanisms of protection and review the beneficial effects of glycine in different disease states.

RECENT FINDINGS

Glycine protects against shock caused by hemorrhage, endotoxin and sepsis, prevents ischemia/reperfusion and cold storage/reperfusion injury to a variety of tissues and organs including liver, kidney, heart, intestine and skeletal muscle, and diminishes liver and renal injury caused by hepatic and renal toxicants and drugs. Glycine also protects against peptidoglycan polysaccharide-induced arthritis and inhibits gastric secretion and protects the gastric mucosa against chemically and stress-induced ulcers. Glycine appears to exert several protective effects, including antiinflammatory, immunomodulatory and direct cytoprotective actions. Glycine acts on inflammatory cells such as macrophages to suppress activation of transcription factors and the formation of free radicals and inflammatory cytokines. In the plasma membrane, glycine appears to activate a chloride channel that stabilizes or hyperpolarizes the plasma membrane potential. As a consequence, agonist-induced opening of L-type voltage-dependent calcium channels and the resulting increases in intracellular calcium ions are suppressed, which may account for the immunomodulatory and antiinflammatory effects of glycine. Lastly, glycine blocks the opening of relatively non-specific pores in the plasma membrane that occurs as the penultimate event leading to necrotic cell death.

SUMMARY

Multiple protective effects make glycine a promising treatment strategy for inflammatory diseases.