Ischemic preconditioning modulates the expression of several genes, leading to the overproduction of IL-1Ra, iNOS, and Bcl-2 in a human model of liver ischemia-reperfusion

PREVENTION OF PATHOLOGICAL EFFECT OF ISCHEMIA-REPERFUSION IN LIVER RESECTION BY SEVOFLURANE PRECONDITIONING

BACKGROUND

The intermittent Pringle maneuver remains the major technique for controlling hemorrhage during liver surgery. Nevertheless, this procedure involves a risk of triggering a cascade of pathological changes resulting in the ischemia-reperfusion injury (I/R) effect. The pharmacological prevention of this I/R injury represents a promising approach. The aim of the study was to compare the effects of pharmacological preconditioning with sevoflurane and propofol-based intravenous anesthesia on the postoperative function of the liver as the primary end-point.

MATERIALS AND METHODS

A prospective cohort study includes the analysis of the data of 73 patients who underwent liver surgery. In the study group (n = 41), preconditioning with sevoflurane inhalation was provided 30 minutes prior to liver resection. In the control group (n = 32), sevoflurane preconditioning was not provided. The primary endpoints were blood lactate concentration shortly after the surgery and one day later; alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities on postoperative Days 1, 3, and 5 as markers of hepatocyte damage.

RESULTS

On postoperative Day 1, in patients of the study group, lactate decreased to preoperative levels, while in the control group, lactate content increased as compared to both preoperative levels and the levels immediately after liver resection. A significant difference in AST activity levels between the groups was registered on Day 5, although this difference was not clinically relevant. The decrease in the prothrombin index in the study group on Day 3 was superior to that in the control group. The multiple regression analysis demonstrated a moderate positive association between the number of resected liver segments and the markers of the functional state of the liver in the study group while in the control group, such association was not significant.

CONCLUSION

The protective effect of sevoflurane on the postoperative function of the liver is manifested by the lower level of blood lactate and the stable level of transaminase activity.

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.

Tissue-Specific Hydrogels Ameliorate Hepatic Ischemia/Reperfusion Injury in Rats by Regulating Macrophage Polarization via TLR4/NF-κB Signaling

Injectable acellular matrix hydrogels are proven to be potential translational materials to facilitate the repairment in various tissues. However, their potential to repair hepatic ischemia/reperfusion injury (IRI) has not been explored. In this work, we made hepatic acellular matrix (HAM) hydrogels based on the decellularized process and evaluated the biocompatibility and hepatoprotective effects in a rat IRI model. HAM hydrogels supported viability, proliferation, and attachment of hepatocytes in vitro. Treatment with HAM hydrogels significantly attenuated hepatic damage caused by IRI, as evidenced by hepatic biochemistry, histology, and inflammatory responses. Importantly, HAM hydrogels inhibited macrophage M1 (CD68/CCR7) differentiation but promoted M2 (CD68/CD206) differentiation. Additionally, TLR4/NF-κB signaling was found to be involved in the hepatoprotective effect of HAM hydrogels. Collectively, our study reveals that HAM hydrogels ameliorate hepatic IRI by facilitating M2 polarization via TLR4/NF-κB signaling.

Transcriptional changes during hepatic ischemia-reperfusion in the rat

There are few effective targeted strategies to reduce hepatic ischemia-reperfusion (IR) injury, a contributor to poor outcomes in liver transplantation recipients. It has been proposed that IR injury is driven by the generation of reactive oxygen species (ROS). However, recent studies implicate other mediators of the injury response, including mitochondrial metabolic dysfunction. We examined changes in global gene expression after transient hepatic ischemia and at several early reperfusion times to identify potential targets that could be used to protect against IR injury. Male Wistar rats were subjected to 30 minutes of 70% partial warm ischemia followed by 0, 0.5, 2, or 6 hours of reperfusion. RNA was extracted from the reperfused and non-ischemic lobes at each time point for microarray analysis. Identification of differentially expressed genes and pathway analysis were used to characterize IR-induced changes in the hepatic transcriptome. Changes in the reperfused lobes were specific to the various reperfusion times. We made the unexpected observation that many of these changes were also present in tissue from the paired non-ischemic lobes. However, the earliest reperfusion time, 30 minutes, showed a marked increase in the expression of a set of immediate-early genes (c-Fos, c-Jun, Atf3, Egr1) that was exclusive to the reperfused lobe. We interpreted these results as indicating that this early response represented a tissue autonomous response to reperfusion. In contrast, the changes that occurred in both the reperfused and non-ischemic lobes were interpreted as indicating a non-autonomous response resulting from hemodynamic changes and/or circulating factors. These tissue autonomous and non-autonomous responses may serve as targets to ameliorate IR injury.

Mitogen Activated Protein Kinases in Steatotic and Non-Steatotic Livers Submitted to Ischemia-Reperfusion

: We analyzed the participation of mitogen-activated protein kinases (MAPKs), namely p38, JNK and ERK 1/2 in steatotic and non-steatotic livers undergoing ischemia-reperfusion (I-R), an unresolved problem in clinical practice. Hepatic steatosis is a major risk factor in liver surgery because these types of liver tolerate poorly to I-R injury. Also, a further increase in the prevalence of steatosis in liver surgery is to be expected. The possible therapies based on MAPK regulation aimed at reducing hepatic I-R injury will be discussed. Moreover, we reviewed the relevance of MAPK in ischemic preconditioning (PC) and evaluated whether MAPK regulators could mimic its benefits. Clinical studies indicated that this surgical strategy could be appropriate for liver surgery in both steatotic and non-steatotic livers undergoing I-R. The data presented herein suggest that further investigations are required to elucidate more extensively the mechanisms by which these kinases work in hepatic I-R. Also, further researchers based in the development of drugs that regulate MAPKs selectively are required before such approaches can be translated into clinical liver surgery.

Remote Ischemic Preconditioning and Protection of the Kidney--A Novel Therapeutic Option

OBJECTIVE

Acute kidney injury is a common complication in critically ill patients and is associated with increased morbidity and mortality. Sepsis, major surgery, and nephrotoxic drugs are the most common causes of acute kidney injury. There is currently no effective strategy available to prevent or treat acute kidney injury. Therefore, novel treatment regimens are required to decrease acute kidney injury prevalence and to improve clinical outcomes. Remote ischemic preconditioning, triggered by brief episodes of ischemia and reperfusion applied in distant tissues or organs before the injury of the target organ, attempts to invoke adaptive responses that protect against acute kidney injury. We sought to evaluate the clinical evidence for remote ischemic preconditioning as a potential strategy to protect the kidney and to review the underlying mechanisms in light of recent studies.

DATA SOURCES

We searched PubMed for studies reporting the effect of remote ischemic preconditioning on kidney function in surgical patients (search terms: "remote ischemic preconditioning," "kidney function," and "surgery"). We also reviewed bibliographies of relevant articles to identify additional citations.

STUDY SELECTION

Published studies, consisting of randomized controlled trials, are reviewed.

DATA EXTRACTION

The authors used consensus to summarize the evidence behind the use of remote ischemic preconditioning.

DATA SYNTHESIS

In addition, the authors suggest patient populations and clinical scenarios in which remote ischemic preconditioning might be best applied.

CONCLUSIONS

Several experimental and clinical studies have shown tissue-protective effects of remote ischemic preconditioning in various target organs, including the kidneys. Remote ischemic preconditioning may offer a novel, noninvasive, and inexpensive treatment strategy for decreasing acute kidney injury prevalence in high-risk patients. Although many new studies have further advanced our knowledge in this area, the appropriate intensity of remote ischemic preconditioning, its mechanisms of action, and the role of biomarkers for patient selection and monitoring are still unknown.

Influence of melatonin on IL-1Ra gene and IL-1 expression in rats with liver ischemia reperfusion injury

The aim of the present study was to explore the influence of melatonin (MT) on rats with liver ischemia reperfusion injury (IRI) and its mechanism. A total of 66 male Sprague-Dawley rats were randomly divided into 3 groups: i) Normal control group, ii) ischemia reperfusion group (IR group) and iii) melatonin treatment group (MT group). Rats in the MT group were administered an intraperitoneal injection of MT (10 mg/kg, 1 ml) at 70 and 35 min before ischemia, early reperfusion, and 1 and 2 h after reperfusion, respectively. Blood was removed at the normal time-point (prior to any processes), 35 min before ischemia, 2, 4, 8 and 24 h after reperfusion. Subsequently the rats were sacrificed. The pathological changes of liver tissues, interleukin-1 receptor antagonist (IL-1Ra) gene and IL-1 expression levels were detected. There were no evident differences between the immediate reperfusion and 2 h IR group and MT group. The liver structure injury of the 4, 8 and 24 h MT groups were improved to various differences compared to the corresponding IR group; liver IL-1β of the MT group at 35 min after ischemia, and 2, 4, 8 and 24 h after reperfusion was evidently lower than that of the IR group (P<0.05); IL-1Ra mRNA expression in the 2 h MT group was higher compared to the 2 h IR group by 4.85-fold; and IL-1Ra mRNA expression in the 4 h MT group was higher compared to the 4 h IR group by 9.34-fold. Differences between two groups at other time-points were <2-fold. In conclusion, MT can upregulate IL-1Ra gene expression by reducing generation of IL-1 thus reducing IRI.

Comparative Effects of Ischemic Preconditioning and Iron Chelation in Hepatectomy

PURPOSE/AIM

Major hepatectomies can result in severe ischemia/reperfusion (I/R) injury of the liver. The aim of this survey is to comparatively evaluate the effects of a surgical and a pharmacological hepatoprotective modality on the liver remnant in a porcine model of hepatectomy.

MATERIAL AND METHODS

Twenty-one Landrace pigs were randomly divided into three groups: a control group (CON) (n = 7), an Ischemic Preconditioning (PRE) group (n = 7) and a Desferoxamine (DFX) treated one (n = 7). Animals were subjected to 120 min of liver ischemia with subsequent 75% hepatectomy followed by 24-hr reperfusion. In all animals, continuous intracranial pressure (ICP) monitoring was employed. Blood samples were collected at t0, t6, t12, and t24 hrs after reperfusion. Liver remnant specimens were excised for histological examination.

RESULTS

In the PRE group, ICP was statistically lower at t6 time point compared to CON group and in comparison with t0. In addition, ICP was significantly lower at all-time points after reperfusion in the DFX group. Finally, with regard to DFX and PRE group correlation, ICP was significantly lower at t0, t12, and t24 time points after reperfusion in the DFX group. In the PRE group, NH3 levels were significantly lower at t12 after reperfusion compared to CON and DFX groups. Histological evaluation elucidated significantly less hepatocellular necrosis, apoptosis, and degeneration in the PRE and DFX groups correlated to CON group.

CONCLUSIONS

Both hepatoprotective modalities including PRE and DFX administration are associated with lower ICP levels and correlated with attenuated liver remnant injury.

Inhibition of inflammatory mediator release from microglia can treat ischemic/hypoxic brain injury

Interleukin-1α and interleukin-1β aggravate neuronal injury by mediating the inflammatory reaction following ischemic/hypoxic brain injury. It remains unclear whether interleukin-1α and interleukin-1β are released by microglia or astrocytes. This study prepared hippocampal slices that were subsequently subjected to oxygen and glucose deprivation. Hematoxylin-eosin staining verified that neurons exhibited hypoxic changes. Results of enzyme-linked immunosorbent assay found that interleukin-1α and interleukin-1β participated in this hypoxic process. Moreover, when hypoxic injury occurred in the hippocampus, the release of interleukin-1α and interleukin-1β was mediated by the P2X4 receptor and P2X7 receptor. Immunofluorescence staining revealed that during ischemia/hypoxia, the P2X4 receptor, P2X7 receptor, interleukin-1α and interleukin-1β expression was detectable in rat hippocampal microglia, but only P2X4 receptor and P2X7 receptor expression was detected in astrocytes. Results suggested that the P2X4 receptor and P2X7 receptor, respectively, mediated interleukin-1α and interleukin-1β released by microglia, resulting in hippocampal ischemic/hypoxic injury. Astrocytes were activated, but did not synthesize or release interleukin-1α and interleukin-1β.

Remote ischemic preconditioning and renoprotection: from myth to a novel therapeutic option?

There is currently no effective prophylactic regimen available to prevent contrast-induced AKI (CI-AKI), a frequent and life-threatening complication after cardiac catheterization. Therefore, novel treatment strategies are required to decrease CI-AKI incidence and to improve clinical outcomes in these patients. Remote ischemic preconditioning (rIPC), defined as transient brief episodes of ischemia at a remote site before a subsequent prolonged ischemia/reperfusion injury of the target organ, is an adaptational response that protects against ischemic and reperfusion insult. Indeed, several studies demonstrated the tissue-protective effects of rIPC in various target organs, including the kidneys. In this regard, rIPC may offer a novel noninvasive and virtually cost-free treatment strategy for decreasing CI-AKI incidence. This review evaluates the current experimental and clinical evidence for rIPC as a potential renoprotective strategy, and discusses the underlying mechanisms and key areas for future research.

Decoding cell death signals in liver inflammation

Inflammation can be either beneficial or detrimental to the liver, depending on multiple factors. Mild (i.e., limited in intensity and destined to resolve) inflammatory responses have indeed been shown to exert consistent hepatoprotective effects, contributing to tissue repair and promoting the re-establishment of homeostasis. Conversely, excessive (i.e., disproportionate in intensity and permanent) inflammation may induce a massive loss of hepatocytes and hence exacerbate the severity of various hepatic conditions, including ischemia-reperfusion injury, systemic metabolic alterations (e.g., obesity, diabetes, non-alcoholic fatty liver disorders), alcoholic hepatitis, intoxication by xenobiotics and infection, de facto being associated with irreversible liver damage, fibrosis, and carcinogenesis. Both liver-resident cells (e.g., Kupffer cells, hepatic stellate cells, sinusoidal endothelial cells) and cells that are recruited in response to injury (e.g., monocytes, macrophages, dendritic cells, natural killer cells) emit pro-inflammatory signals including - but not limited to - cytokines, chemokines, lipid messengers, and reactive oxygen species that contribute to the apoptotic or necrotic demise of hepatocytes. In turn, dying hepatocytes release damage-associated molecular patterns that-upon binding to evolutionary conserved pattern recognition receptors-activate cells of the innate immune system to further stimulate inflammatory responses, hence establishing a highly hepatotoxic feedforward cycle of inflammation and cell death. In this review, we discuss the cellular and molecular mechanisms that account for the most deleterious effect of hepatic inflammation at the cellular level, that is, the initiation of a massive cell death response among hepatocytes.

Does pharmacological conditioning with the volatile anaesthetic sevoflurane offer protection in liver surgery?

BACKGROUND

A recently published randomized control trial (RCT) showed a protection of the remnant liver from ischemia-reperfusion (I/R) injury by pharmacological pre-conditioning with a volatile anaesthetic in patients undergoing hepatic resection. Whether the continuous application of volatile anaesthetics (pharmacological conditioning) also protects against I/R injury is unknown.

METHODS

Consecutive patients undergoing liver resection with inflow occlusion from 2005-2007 were included in the trial. Two groups of anaesthesia regimens with either continuous application of the volatile anaesthetic sevoflurane (pharmacological conditioning) or continuous infusion of the intravenous (i.v.) anaesthetic propofol (control group) were compared. Endpoints were serum-peak-aspartate aminotransferase (AST)/ alanine aminotranferease (ALT) levels, length of stay (LOS) and intensive care unit (ICU) stays, and the occurrence of post-operative complications.

RESULTS

Two hundred and twenty-seven patients were included. Pharmacological conditioning did not protect the remnant liver from IR injury (adjusted difference for peak-AST:61.9 U/l, 95% confidence interval (CI): -151.7-275.4 U/l, P = 0.568; peak-ALT:136.1 U/l, 95% CI: -113.7-385.9 U/l, P = 0.284) nor reduce LOS (adjusted difference 0.9 days, 95% CI: -2.6-4.3 days, P = 0.622) or ICU stay (1.6 days, 95% CI: -0.2-3.3 days, P = 0.079), and was not associated with reduced complication rates (adjusted OR 1.12, 95% CI:0.6-2.3, P = 0.761) compared with the control group.

CONCLUSION

In this retrospective study, continuous volatile anaesthesia in liver resection does not provide protection of the remnant liver from IR injury compared with continuous i.v. anaesthesia.

Immediately transcripted genes in various hepatic ischemia models

PURPOSE

To elucidate the characteristic gene transcription profiles among various hepatic ischemia conditions, immediately transcribed genes and the degree of ischemic injury were compared among total ischemia (TI), intermittent clamping (IC), and ischemic preconditioning (IPC).

METHODS

Sprague-Dawley rats were equally divided into control (C, sham-operated), TI (ischemia for 90 minutes), IC (ischemia for 15 minutes and reperfusion for 5 minutes, repeated six times), and IPC (ischemia for 15 minutes, reperfusion for 5 minutes, and ischemia again for 90 minutes) groups. A cDNA microarray analysis was performed using hepatic tissues obtained by partial hepatectomy after occluding hepatic inflow.

RESULTS

THE CDNA MICROARRAY REVEALED THE FOLLOWING: interleukin (IL)-1β expression was 2-fold greater in the TI group than in the C group. In the IC group, IL-1α/β expression increased by 2.5-fold, and Na+/K+ ATPase β1 expression decreased by 2.4-fold. In the IPC group, interferon regulatory factor-1, osteoprotegerin, and retinoblastoma-1 expression increased by approximately 2-fold compared to that in the C group, but the expression of Na+/K+ ATPase β1 decreased 3-fold.

CONCLUSION

The current findings revealed characteristic gene expression profiles under various ischemic conditions. However, additional studies are needed to clarify the mechanism of protection against IPC.

Recent advances in liver preconditioning: Thyroid hormone, n-3 long-chain polyunsaturated fatty acids and iron

Liver preconditioning (PC), defined as an enhanced tolerance to injuring stimuli induced by previous specific maneuvers triggering beneficial functional and molecular changes, is of crucial importance in human liver transplantation and major hepatic resection. For these reasons, numerous PC strategies have been evaluated in experimental models of ischemia-reperfusion liver injury, which have not been transferred to clinical application due to side effects, toxicity and difficulties in implementation, with the exception of the controversial ischemic PC. In recent years, our group has undertaken the assessment of alternate experimental liver PC protocols that might have application in the clinical setting. These include thyroid hormone (T(3)), n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA), or iron, which suppressed liver damage due to the 1 h ischemia-20 h reperfusion protocol. T(3), n-3 LCPUFA and iron are hormetic agents that trigger biologically beneficial effects in the low-dose range, whose multifactorial mechanisms of action are discussed in the work.

The nitric oxide pathway--evidence and mechanisms for protection against liver ischaemia reperfusion injury

Ischaemia reperfusion (IR) injury is a clinical entity with a major contribution to the morbidity and mortality of liver surgery and transplantation. A central pathway of protection against IR injury utilizes nitric oxide (NO). Nitric oxide synthase (NOS) enzymes manufacture NO from L-arginine. NO generated by the endothelial NOS (eNOS) isoform protects against liver IR injury, whereas inducible NOS (iNOS)-derived NO may have either a protective or a deleterious effect during the early phase of IR injury, depending on the length of ischaemia, length of reperfusion and experimental model. In late phase hepatic IR injury, iNOS-derived NO plays a protective role. In addition to NOS consumption of L-arginine during NO synthesis, this amino acid may also be metabolized by arginase, an enzyme whose release is increased during prolonged ischaemia, and therefore diverts L-arginine away from NOS metabolism leading to a drop in the rate of NO synthesis. NO most commonly acts through the soluble guanylyl cyclase-cyclic GMP- protein kinase G pathway to ameliorate hepatic IR injury. Both endogenously generated and exogenously administered NO donors protect against liver IR injury. The beneficial effects of NO on liver IR are not, however, universal, and certain conditions, such as steatosis, may influence the protective effects of NO. In this review, the evidence for, and mechanisms of these protective actions of NO are discussed, and areas in need of further research are highlighted.

Effect of intermittent hepatic inflow occlusion with the Pringle maneuver during donor hepatectomy in adult living donor liver transplantation with right hemiliver grafts: a prospective, randomized controlled study

To evaluate the effects of intermittent hepatic inflow occlusion (IHIO) during donor hepatectomy for living donor liver transplantation (LDLT) in recipients and donors, we performed a single-center, open-label, prospective, parallel, randomized controlled study. Adult donor-recipient pairs undergoing LDLT with right hemiliver grafts were randomized into IHIO and control groups (1:1). In the IHIO group, IHIO was performed during donor hepatectomy. The primary endpoint was the peak serum alanine aminotransferase (ALT) concentration in the recipients within 5 days after the operation. Blood samples for measurements of interleukin-6 (IL-6), IL-8, tumor necrosis factor α (TNF-α), and hepatocyte growth factor (HGF) were taken from the donors and the recipients during the operation and postoperatively. Biopsy samples for measurements of caspase-3 and malondialdehyde (MDA) were taken from the donors and the recipients. In all, 50 donor-recipient pairs (ie, 25 pairs in each group) completed this study. The mean peak serum ALT levels within 5 days after the operation did not differ in the recipients between the 2 groups (P = 0.32) but were higher in the donors of the IHIO group (P = 0.002). There were no differences in the prothrombin times or total bilirubin levels in the recipients or donors between the 2 groups. The amount of blood loss during donor hepatectomy was significantly lower in the IHIO group versus the control group (P = 0.02). The mean hospital stay for donors was 19.3 ± 7.2 days in the control group and 15.8 ± 4.6 days in the IHIO group (P = 0.046). There were no in-hospital deaths within 1 month and no cases of primary nonfunction or initially poor function in the 2 groups. The concentrations of IL-6, IL-8, TNF-α, and HGF did not differ between the 2 groups, nor did the concentrations of caspase-3 and MDA. In conclusion, although we found differences in postoperative peak serum ALT levels in donors, donor hepatectomy with IHIO for LDLT using a right hemiliver graft with a graft-to-recipient body weight ratio > 0.9% and <30% steatosis can be a tolerable procedure for donors and recipients.

Transcriptional analysis of infiltrating T cells in kidney ischemia-reperfusion injury reveals a pathophysiological role for CCR5

Although T cells have been shown to play a direct role in kidney ischemia-reperfusion injury (IRI), little is known about the underlying mechanisms. We hypothesized that studying the transcriptional responses in kidney-infiltrating T cells would help elucidate novel therapeutic targets for kidney IRI. Unilateral renal pedicle clamping for 45 min was performed in male C57BL/6 mice, and CD3(+) T cells were isolated from the kidney and purified. Transcriptional activities of T cell were measured by array-based PCR compared between ischemic kidneys and contralateral nonischemic kidneys. Among total of 89 genes analyzed, 24, 22, 24, and 37 genes were significantly changed at 6 h, day 3, day 10, and day 28 after IRI. Genes associated with cytokines, chemokines, and costimulatory molecules were upregulated. Pathway analysis identified CC motif chemokine receptor 5 (CCR5) as a candidate pathophysiological pathway. CCR5 upregulation was validated at the protein level, and CCR5 blockade improved renal function after kidney IRI. Using discovery techniques to identify transcriptional responses in purified kidney-infiltrating cells enabled the elucidation of novel mechanisms and therapeutic targets for IRI.

Impact of reversible cardiac arrest in the brain-dead organ donor on the outcome of adult liver transplantation

Several donor and graft characteristics are associated with higher failure rates for deceased donor liver transplantation (LT). The influence of reversible cardiac arrest in the donor on these failure rates is unclear because of scarce and inconsistent data. The aim of this study was to determine whether reversible cardiac arrest in the donor could affect the early postoperative outcome of LT. From January 2008 to February 2010, 165 patients underwent LT, and they were retrospectively divided into 2 groups: a cardiac arrest group (34 patients who received grafts from donors who had experienced reversible cardiac arrest before organ procurement) and a control group (131 patients who received grafts from donors without a history of reversible cardiac arrest). The postoperative complications and the graft and recipient outcomes were prospectively recorded for all the patients. Graft failure was defined as death or the need for retransplantation within 90 days of LT. Donors in the cardiac arrest group displayed higher serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels than donors in the control group [AST: 104 (19-756) versus 42 IU/L (10-225 IU/L), P < 0.001; ALT: 73 (13-869) versus 29 IU/L (6-549 IU/L), P < 0.001]. However, no difference in the graft failure rates was found between the 2 groups (11.8% versus 8.4%, P = 0.51). The biological parameters 5 and 7 days after LT and the peak AST/ALT levels were similar for the 2 groups. Furthermore, the 2 groups had similar graft and patient survival rates at the 6-month mark (87% and 88%, respectively). In conclusion, our study shows that brief and reversible cardiac arrest in organ donors does not affect post-LT allograft survival and function, even though liver function test values are higher for these donors. However, the risk of using these grafts needs to be balanced against the potential benefits for the recipients.

Nitric oxide is an essential mediator of the protective effects of remote ischaemic preconditioning in a mouse model of liver ischaemia/reperfusion injury

NO (nitric oxide) may protect the liver from IR (ischaemia/reperfusion) injury. RIPC (remote ischaemic preconditioning) also protects against liver IR injury; however, the molecular mediator(s) of RIPC are currently unknown. The aim of the present study was to assess the role of NO in hindlimb RIPC-induced protection against liver IR injury. Mice were allocated to the following groups: sham group; RIPC group (six cycles of 4×4 min IR of hindlimb); IR group [40 min lobar (70%) hepatic ischaemia and 2-h reperfusion]; RIPC+IR group (RIPC followed by IR group procedures); and C-PTIO [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt]+RIPC+IR group [C-PTIO (a direct NO scavenger) was administered, followed by the RIPC+IR group procedure]. Hepatic MBF (microcirculatory blood flow) was measured throughout the experiment. Circulating NOx (nitrite and nitrate) levels, plasma liver transaminases, hepatic histopathological and TEM (transmission electron microscopy) studies were performed at the end of the experiment. NOx concentrations were significantly elevated (P<0.05) in the RIPC and RIPC+IR groups. Compared with liver IR alone, RIPC+IR preserved hepatic MBF during liver reperfusion (P<0.05). In contrast, C-PTIO+RIPC+IR reduced MBF compared with RIPC+IR (P<0.05). RIPC+IR reduced plasma transaminases (P<0.05), and histopathological and ultrastructural features of injury compared with IR alone. The protective effects of RIPC+IR in reducing liver IR injury were abrogated in the group that received antecedent C-PTIO (C-PTIO+RIPC+IR). In conclusion, NO is an essential mediator of the protection afforded by hindlimb RIPC against liver IR injury. The mechanisms underlying this protection involve preservation of the sinusoidal structure and maintenance of blood flow through the hepatic microcirculation.

Ischemic preconditioning attenuates lactate release by the liver during hepatectomies under vascular control: a case-control study

BACKGROUND

We have previously demonstrated lactate release by the liver itself in hepatectomies performed under selective hepatic vascular exclusion. We hypothesized that ischemic preconditioning applied in this setting might lead to a reduction of hepatic lactate production.

METHODS

Twenty-one patients underwent hepatectomy under inflow and outflow occlusion combined with ischemic preconditioning (IP group, n = 21). These patients were matched 1:1 with patients subjected to the same technique of hepatectomy under vascular occlusion without ischemic preconditioning (control group, n = 21). The transhepatic lactate gradient (hepatic vein-portal vein) was calculated before liver dissection and 60 min post-reperfusion.

RESULTS

In the control group, the transhepatic lactate gradient before liver resection was negative indicating consumption by the liver. After 60 min post-reperfusion, this gradient became positive, indicating net lactate production by the liver (0.2 ± 0.3 vs. -0.3 ± 0.2 mmol/L, P < 0.001). In the IP group, the liver consumed lactate both before resection and 60 min post-reperfusion (gradients -0.2 ± 1.1 and -0.1 ± 0.6 mmol/L, respectively). The magnitude of lactate release by the liver correlated with systemic hyperlactatemia post-reperfusion and 24 h postoperatively (r(2) = 0.54, P < 0.001 and r(2) = 0.67, P < 0.001, respectively). Significant correlations between the transhepatic lactate gradient post-reperfusion and peak postoperative AST as well as the apoptotic response of the liver remnant were also demonstrated (r(2) = 0.72, P < 0.001 and r(2) = 0.66, P < 0.001, respectively).

CONCLUSION

The microcirculatory derangement and cellular aerobic metabolism breakdown elicited by ischemia-reperfusion insults can be prevented with hepatoprotective measures such as ischemic preconditioning. The transhepatic lactate gradient could act as a monitoring and prognostic tool of the efficacy of ischemic preconditioning.

Ischemic preconditioning induces autophagy and limits necrosis in human recipients of fatty liver grafts, decreasing the incidence of rejection episodes

Whether ischemic preconditioning (IP) reduces ischemia/reperfusion (I/R) injury in human normal and fatty livers remains controversial. We compared two independent groups of liver donor transplants with versus without steatosis to evaluate IP consequences. Liver donors with (n=22) or without (n=28) steatosis either did or did not undergo IP before graft retrieval. Clinical data from the recipients, as well as histological and immunohistological characteristics of post-reperfusion biopsies were analyzed. Incidence of post-reperfusion necrosis was increased (10/10 versus 9/14, respectively; P<0.05) and the clinical outcome of recipients was worse for non-IP steatotic liver grafts compared with non-IP non-steatotic grafts. IP significantly lowered the transaminase values only in patients receiving a non-steatotic liver. An increased expression of beclin-1 and LC3, two pro-autophagic proteins, tended to decrease the incidence of necrosis (P=0.067) in IP steatotic livers compared with non-IP steatotic group. IP decreased the incidence of acute and chronic rejection episodes in steatotic livers (2/12 versus 6/10; P=0.07 and 2/12 versus 7/10; P<0.05, respectively), but not in non-steatotic livers. Thus, IP may induce autophagy in human steatotic liver grafts and reduce rejection in their recipients.

Molecular mechanisms of liver preconditioning

Ischemia/reperfusion (I/R) injury still represents an important cause of morbidity following hepatic surgery and limits the use of marginal livers in hepatic transplantation. Transient blood flow interruption followed by reperfusion protects tissues against damage induced by subsequent I/R. This process known as ischemic preconditioning (IP) depends upon intrinsic cytoprotective systems whose activation can inhibit the progression of irreversible tissue damage. Compared to other organs, liver IP has additional features as it reduces inflammation and promotes hepatic regeneration. Our present understanding of the molecular mechanisms involved in liver IP is still largely incomplete. Experimental studies have shown that the protective effects of liver IP are triggered by the release of adenosine and nitric oxide and the subsequent activation of signal networks involving protein kinases such as phosphatidylinositol 3-kinase, protein kinase C δ/ε and p38 MAP kinase, and transcription factors such as signal transducer and activator of transcription 3, nuclear factor-κB and hypoxia-inducible factor 1. This article offers an overview of the molecular events underlying the preconditioning effects in the liver and points to the possibility of developing pharmacological approaches aimed at activating the intrinsic protective systems in patients undergoing liver surgery.

Hormetic responses of thyroid hormone calorigenesis in the liver: Association with oxidative stress

Thyroid hormone (L-3,3',5-triiodothyronine, T(3)) exerts calorigenic effects by accelerating mitochondrial O(2) consumption through transcriptional activation of respiratory genes, with consequent increased reactive oxygen species (ROS) production. In the liver, ROS generation occurs at different sites of hepatocytes and in the respiratory burst of Kupffer cells, triggering the activation of the transcription factors nuclear factor-kappaB, signal transducer and activator of transcription 3, and activating protein 1. Under these conditions, the redox upregulation of Kupffer cell-dependent expression of cytokines [tumor necrosis factor-alpha, interleukin (IL)-1, and IL-6] is achieved, which upon interaction with specific receptors in hepatocytes trigger the expression of antioxidant enzymes (manganese superoxide dismutase, inducible nitric oxide synthase), antiapoptotic proteins (Bcl-2), and acute-phase proteins (haptoglobin, beta-fibrinogen). These responses and the promotion of hepatocyte and Kupffer cell proliferation observed represent hormetic effects re-establishing redox homeostasis, promoting cell survival, and protecting the liver against ischemia-reperfusion (IR) injury. It is proposed that hormesis underlying T(3) action may constitute a novel preconditioning strategy for IR injury during liver surgery in man or in liver transplantation using reduced-size grafts from living donors, considering that (i) with the exception of the controversial ischemic preconditioning, all other studied strategies have failed to reach the clinical setting and (ii) T(3) is a well-tolerated therapeutic agent that either lacks major adverse effects or has minimal and controlled side effects.

Ischaemic preconditioning of the graft in adult living related right lobe liver transplantation: impact on ischaemia-reperfusion injury and clinical relevance

BACKGROUND

Ischaemic preconditioning (IPC) of the right liver graft in the donor has not been studied in adult-to-adult living related liver transplantation (LRLT).

OBJECTIVE

To assess the IPC effect of the graft on ischaemia reperfusion injury in the recipient and compare recipient and donor outcomes with and without preconditioned grafts.

PATIENTS AND METHODS

Alternate patients were transplanted with right lobe grafts that were (n = 22; Group (Precond)) or were not (n = 22; Group (Control)) subjected to IPC in the living donor. Liver ischaemia-reperfusion injury, liver/kidney function, morbidity/mortality rates and outcomes were compared. Univariate and multivariate analyses were performed to identify factors predictive of the aspartate aminotransferase (AST) peak and minimum prothrombin time.

RESULTS

Both groups had similar length of hospital stay, morbidity/mortality, primary non-function and acute rejection rates. Post-operative AST (P = 0.8) and alanine aminotransferase (ALT) peaks (P = 0.6) were similar in both groups (307 +/- 189 and 437 +/- 302 vs. 290 +/- 146 and 496 +/- 343, respectively). In univariate analysis, only pre-operative AST and warm ischemia time (WIT) were significantly associated with post-operative AST peak (in recipients). In multivariate analysis, the graft/recipient weight ratio (P = 0.003) and pre-operative bilirubin concentration (P = 0.004) were significantly predictive of minimum prothrombin time post-transplantation.

CONCLUSIONS

Graft IPC in the living related donor is not associated with any benefit for the recipient or the donor and its clinical value remains uncertain.

Volatile anesthetics might be more beneficial than propofol for postoperative liver function in cirrhotic patients receiving hepatectomy

Hepatic inflow occlusion during the liver surgery may result in a transient ischemia period followed by reperfusion, and may initiate liver injury and lead to postoperative liver dysfunction. Especially in cirrhotic patients, the tolerance time of ischemia is much shorter and the outcome would be worse. Recently, clinical trials had proved that volatile anesthetics rather than propofol can protect myocardial cells from ischemia reperfusion (IR) injury in cardiac surgery. Meanwhile, animal studies had revealed that volatile anesthetics could induce some endogenous protective molecules in the liver such as hypoxia induced factor-1 (HIF-1), heme oxygenase (HO) enzyme system and inducible nitric oxide synthase (iNOS), which make the volatile anesthetics posing the extraordinary anti-oxidative, anti-inflammatory, anti-apoptotic, and vasodilatory characteristics. However, there is still lack of trials to compare the postoperative outcomes such as liver function in cirrhotic patients undergoing liver surgery with inflow occlusion between volatile anesthetics and propofol anesthesia. Hence we hypothesize that with its anti-IR injury characteristics, volatile anesthetics might be the more appropriate choice in cirrhotic patients undergoing liver surgery with occlusion.

Ischemic preconditioning confers antiapoptotic protection during major hepatectomies performed under combined inflow and outflow exclusion of the liver. A randomized clinical trial

BACKGROUND

Extensive experimental studies and a few clinical series have shown that ischemic preconditioning (IPC) attenuates oxidative ischemia/reperfusion (I/R) injuries in liver resections performed under inflow vascular control. Selective hepatic vascular exclusion (SHVE) employed during hepatectomies completely deprives the liver of blood flow, as it entails simultaneous clamping of the portal triad and the main hepatic veins. The aim of the present study was to identify whether IPC can also protect hepatocytes during liver resections performed under SHVE.

METHODS

Patients undergoing major liver resection were randomly assigned to have either only SHVE (control group, n = 43) or SHVE combined with IPC--10 min of ischemia followed by 15 min of reperfusion before SHVE was applied (IPC group, n = 41).

RESULTS

The two groups were comparable with regard to age, liver resection volume, blood loss and transfusions, warm ischemic time, and total operative time. In liver remnant biopsies obtained 60 min post-reperfusion, IPC patients had significantly fewer cells stained positive by TUNEL compared to controls (19% +/- 8% versus 45% +/- 12%; p < 0.05). Also IPC patients had attenuated hepatocyte necrosis, systemic inflammatory response, and oxidative stress as manifested by lower postoperative peak values of aspartate transaminase, interleukin-6, interleukin-8, and malondialdehyde compared to controls. Morbidity was similar for the two groups, as were duration of intensive care unit stay and extent of total hospital stay.

CONCLUSIONS

In major hepatectomies performed under SHVE, ischemic preconditioning appears to attenuate apoptotic response of the liver remnant, possibly through alteration of inflammatory and oxidative pathways.

The strategy of combined ischemia preconditioning and salvianolic acid-B pretreatment to prevent hepatic ischemia-reperfusion injury in rats

BACKGROUND

Ischemia-reperfusion injury (IRI) is a serious complication of liver surgery, especially for extended hepatectomy and liver transplantation. The aim of this study was to evaluate the protective effect of combined ischemic preconditioning (IPC) and salvianolic acid-B (Sal-B) pretreatment against IRI-induced hepatocellular injury.

METHODS

Sixty male Wistar rats weighing around 200 g were randomized into five groups (n=12): sham group: only anesthesia and laparotomy; IR group: 90 min sustained ischemia by blocking the left ortal vessels; IPC group: 10 min ischemia and 10 min reperfusion prior to the sustained ischemia; Sal-B group: 10 mg/kg injection of Sal-B intravenously 10 min prior to the sustained ischemia; IPC+Sal-B group: same IPC procedure as in IPC group, but proceeded by intravenous administration of Sal-B 10 min prior to sustained ischemia. After 5 h of reperfusion, serum levels of ALT and AST were measured; the amount of malondialdehyde (MDA) and adenine nucleotides in liver tissue was determined; the expression of Bcl-2 and caspase-3 was detected by immunofluorescent and western blotting techniques; the severity of apoptosis and pathological alterations was evaluated by TUNEL and H&E staining, respectively.

RESULTS

The serum aminotransferases, hepatic MDA concentration, and apoptotic index in groups IPC, Sal-B, and IPC+Sal-B were significantly lower than those in the IR group (P<0.001), while the IPC+Sal-B group had the lowest values among these groups (P<0.05). Compared with the IR group, groups IPC and Sal-B not only had statistically higher ATP levels and energy charge (EC) values (P<0.01), but also had upregulated Bcl-2 expression and downregulated cleaved caspase-3 expression in liver tissue. All these effects were further augmented in the IPC+Sal-B group. Liver histopathological findings were consistent with these results.

CONCLUSIONS

Based on these results, the combined IPC and Sal-B pretreatment had a synergistically protective effect on liver tissue against IRI, which might be due to decreased post-ischemic oxidative stress, improved energy metabolism, and reduced hepatocellular apoptosis.

Effect of ischemic preconditioning on the genomic response to reperfusion injury in deceased donor liver transplantation

Ischemic preconditioning (IP) is an effective method for protecting organs from ischemia/reperfusion (IR) injury; however, the molecular basis of this protective effect is poorly understood. This study assessed the gene expression profile in liver allografts during transplantation and evaluated the impact of IP. Prereperfusion and postreperfusion biopsy specimens from livers subjected to IP (n = 19) or no preconditioning (the IR group; n = 16) were obtained. Total RNA was extracted and hybridized to GeneChip microarrays, and the findings were validated with real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR). IP livers showed less of an increase in aspartate aminotransferase after transplantation. A microarray analysis of the IR group showed increased expression of 57 genes mainly involved in cell death, inflammation and immune response, stress, and modulation of the cell cycle. The IP group showed attenuation of the expression of these genes after reperfusion. Additionally, IP led to increased expression of 43 genes involved in growth and maintenance, cell-cycle regulation, proliferation, and development. The expression of the 12 most significant genes was validated in all patients with real-time qRT-PCR, and the fold changes of a number of genes correlated with clinical parameters and graft outcomes. IP protection of liver allografts was associated with a reduction in the expression of immune response genes and promotion of those involved in protection and repair.

Concurrent induction of necrosis, apoptosis, and autophagy in ischemic preconditioned human livers formerly treated by chemotherapy

BACKGROUND/AIMS

Liver pathology induced by chemotherapy (steatosis or vascular injury) is known to increase the liver's sensitivity to ischemia/ reperfusion (I/R) injury, thereby increasing morbidity and mortality after liver resection. Our aim was to assess whether ischemic preconditioning (IP) reduces I/R injury to livers with chemotherapy-induced pathology.

METHODS

We analyzed a series of livers from patients treated with chemotherapy for colorectal cancer who underwent IP (n=30) or not (n=31) before hepatectomy. All but one of the livers exhibited chemotherapy-induced steatosis and/ or peliosis before the I/R insult.

RESULTS

Necrosis was less frequent (p=0.038) in livers with IP than in the others. IP had no influence on apoptosis as assessed by terminal transferase uridyl nick-end labeling (TUNEL) assay or caspase-3, -8 and -9 expression. IP induced a twofold increase in B-cell leukemia/ lymphoma 2 (Bcl-2; p<0.05), which was localized to hepatocytes of centrolobular and peliotic areas and colocalized with the autophagy protein beclin-1 in livers with IP, suggesting their coordinated role in autophagy. Increased expression of the phosphorylated Bcl-2 was observed in preconditioned livers and was associated with a decreased immunoprecipitation of beclin-1 and the increased expression of light chain 3 type II (LC3-II). The increased number of autophagic vacuoles seen by electron microscopy confirmed an association of autophagy in chemotherapy-injured livers following IP. However, the differences in protein expression were not reflected in postresection liver-injury tests or measure of patient morbidity.

CONCLUSIONS

IP is associated with a reduction in necrosis of hepatocytes already damaged by chemotherapy and an activation of autophagy. Bcl-2 and beclin-1 could be major targets in the regulation of cell death during I/R injury.

Unilateral ischemic preconditioning and heterologous preconditioning in living donor liver transplantation

Ischemic preconditioning (IP) exerts a protective effect on tissues undergoing prolonged ischemia. No studies have been performed to assess the clinical impact of IP on normal human liver used for living donor transplantation (LDLT). Heterologous preconditioning (HP) protects liver tissue as demonstrated in a rat model. Our study investigates the impact that IP and HP have on the donor and recipient liver in LDLT. Twenty candidates for living donor right hepatectomy were divided in two groups. The study group underwent 10' unilateral ischemia by clamping the right portal vein and hepatic artery at the end of the parenchymal transection. Demographics, laboratory values, biopsy studies, IL-1Ra, Ki-67, and CytoDEATH stains were compared. The results show that 10' ischemia does not exert significant clinical and laboratory changes in living donor hepatectomy candidates.

Ischemic preconditioning-induced neuroprotection is associated with differential expression of IL-1beta and IL-1 receptor antagonist in the ischemic cortex

Ischemic preconditioning (IP) is a phenomenon that organs develop a tolerance toward subsequent lethal ischemic insults. Among the factors that are involved in IP, IL-1beta and its endogenous receptor antagonist IL-1ra have been identified as important players in the induction of IP. The present study investigated whether IP affects the levels of these two antagonistic proteins during tolerance and reperfusion periods after ischemic stroke. The IP 24 h prior to ischemic stroke resulted in neuroprotection in the cortex. IP-induced protection is accompanied by increased IL-1beta gene and IL-1ra gene and protein levels during the tolerance period. In the post-ischemic cortex, IP resulted in the suppression of IL-1beta mRNA and protein levels at 6 h without affecting IL-1ra expression and the up-regulation of IL-1ra protein at 24 h. These findings demonstrate that IP differentially regulates cortical IL-1beta and IL-1ra expression before and after ischemic stroke and suggest that the shift toward an anti-inflammatory state in the post-ischemic cortex may contribute to IP-induced neuroprotection.

A randomized controlled trial on pharmacological preconditioning in liver surgery using a volatile anesthetic

OBJECTIVE

To evaluate the effects of pharmacological preconditioning with a volatile anesthetic in patients undergoing liver resection with inflow occlusion.

BACKGROUND

In liver surgery, ischemic preconditioning and intermittent clamping are the only established protective strategies to reduce tissue damage due to ischemia during inflow occlusion. Preconditioning with volatile anesthetics has provided protection against cardiac and renal ischemic injury in several animal models through NO and HO-1 pathways. But pharmacological preconditioning has never been tested in patients undergoing liver surgery in a randomized trial.

METHODS

Sixty-four patients undergoing liver surgery with inflow occlusion were randomized intraoperatively for preconditioning with sevoflurane or not (ClinicalTrials.gov NCT00516711). Anesthesia was performed intravenously with propofol. Thirty minutes before inflow occlusion propofol was replaced by sevoflurane in the preconditioning group. Primary endpoint was postoperative liver injury assessed by peak values of liver transaminases. Postoperative complications were recorded according to an established scoring system.

RESULTS

Sevoflurane preconditioning significantly limited the postoperative increase of serum transaminase levels by 261 U/L (95% CI, 65 to 458; P = 0.01) for the ALT and by 239 (95% CI, -2 to 480; P = 0.05) for the AST corresponding to decreases of baseline levels of 35% and 31%, respectively. Patients with steatosis had an even better benefit than patients without steatosis. The rates of any complication (risk ratio 0.46; 95% CI, 0.25 to 0.85; P = 0.006) and of severe complications requiring invasive procedures (risk ratio 0.25; 95% CI, 0.06 to 1.08; P = 0.05) were also lowered by preconditioning.

CONCLUSION

This first randomized trial of pharmacological preconditioning in liver surgery in humans showed a protective effect of preconditioning with volatile anesthetics. This strategy may provide a new and easily applicable therapeutic option to protect the liver and to lower complication rates.

Ischemic preconditioning in hepatic ischemia and reperfusion

PURPOSE OF REVIEW

Ischemic preconditioning that consists of a short period of hepatic inflow occlusion followed by reperfusion has the potential to increase tolerance to a subsequent prolonged ischemic insult. This review outlines current insight into ischemic preconditioning for hepatic ischemia and reperfusion injury in experimental and clinical settings.

RECENT FINDINGS

Experimental evidence suggests that interleukin-6 signaling and increased phosphorylation of STAT3 (signal transducer and activator of transcription-3) are involved in the protective effects of ischemic preconditioning. The benefit of ischemic preconditioning is restricted, however, by old liver and prolonged ischemic time (>60 min). To overcome this, ascorbic acid or glucose administration combined with ischemic preconditioning potentially can maintain the integrity of hepatic mitochondrial function through signal transduction pathways. The influence of ischemic preconditioning on hepatic regeneration varies with partial hepatectomy or small-for-size liver graft models, and remains controversial. Clinically, ischemic preconditioning in deceased donors protects against ischemia and reperfusion injury, as demonstrated by lowered liver enzyme levels, reduced incidence of primary nonfunction, and increased hepatic hypoxia-induced factor-1alpha concentrations.

SUMMARY

Enhanced understanding of the mechanisms of organ tolerance induced by ischemic preconditioning would strengthen the significance of this potential therapeutic strategy in liver transplantation.

Potential roles for the PIM1 kinase in human cancer - a molecular and therapeutic appraisal

In vitro experiments have shown the PIM1 kinase to have diverse biological roles in cell survival, proliferation and differentiation. In humans, PIM1 is often expressed in both normal and transformed cells. The PIM1 kinase is a true oncogene implicated in early transformation and tumour progression in haematopoietic malignancies and prostate carcinomas. It is associated with aggressive subgroups of lymphoma, is a marker of poor prognosis in prostate carcinomas and has been suggested to have a role in hormone insensitivity of prostate malignancies. PIM1 has a possible role in other carcinomas with 6p21 genomic alterations. On one hand, PIM1 (due to its role in malignancy) appears to be a promising target for drug development programmes but, on the other hand, the complexity of its molecular structure has posed challenges in the development of PIM1 inhibitors. In this review we discuss PIM1 expression in human tissues (including some new data from our laboratory), its role in human malignancies, as well as the possibilities and challenges in the development of target therapy for PIM1.

Endogenous neuroprotection: mitochondria as gateways to cerebral preconditioning?

From single to multicellular organisms, protective mechanisms have evolved against endogenous and exogenous noxious stimuli. Preconditioning paradigms, in which stimulation below the threshold of injury results in subsequent protection of the brain, have played an important role in elucidating such endogenous protective mechanisms. Consequently, over the past decades numerous signaling pathways have been discovered by which the brain senses and reacts to such insults as neurotoxins, substrate deprivation, or inflammation. Research on preconditioning is aimed at understanding endogenous neuroprotection to boost it, or to supplement its effectors therapeutically once damage to the brain has occurred, such as after stroke or brain trauma. Another goal of establishing preconditioning protocols is to induce endogenous neuroprotection in anticipation of incipient brain damage. Currently several endogenous neuroprotectants are being investigated in controlled clinical trials. In the present review we will give a short overview on the signals, sensors, transducers, and effectors of endogenous neuroprotection. We will first focus on common mechanisms, on which pathways of endogenous neuroprotection converge, and in particular on mitochondria, which may be considered master integrators of endogenous neuroprotection. We will then discuss various applications of preconditioning, including pharmacological and anesthetic preconditioning, as well as postconditioning, and explore the prospects of endogenous neuroprotective therapeutic approaches.

Cardiotrophin-1 is an essential factor in the natural defense of the liver against apoptosis

We previously reported that exogenous cardiotrophin-1 (CT-1), a member of the IL-6 family of cytokines, exerts hepatoprotective effects. Because CT-1 is expressed in the normal liver, we hypothesized that this cytokine may constitute an endogenous defense of the liver against proapoptotic stimuli. Here, we found that CT-1-/- mice died faster than wild-type animals after challenge with a lethal dose of the Fas agonist Jo-2. At sublethal doses of Jo-2, all wild-type mice survived whereas CT-1-/- animals developed extensive hepatocyte apoptosis with 50% mortality at 24 hours. Pretreatment with CT-1 improved survival and reduced injury in both CT-1-/- and wild-type animals. Upon Fas ligation the activation of STAT-3, a molecule that defends the liver against apoptosis, was lower in CT-1-/- mice than in wild-type animals despite similar IL-6 up-regulation in the 2 groups. Analysis of liver transcriptome in CT-1-/- and wild-type mice showed that 9 genes reported to be associated with cell survival/death functions were differentially expressed in the 2 groups. Four of these genes [IGFBP1, peroxiredoxin3, TNFR1, and calpastatin (endogenous inhibitor of calpain)] could be validated by real-time PCR. All of them were down-regulated in CT-1-/- mice and were modulated by CT-1 administration. Treatment of CT-1-/- animals with the calpain inhibitor MDL28170 afforded significant protection against Fas-induced liver injury.

CONCLUSION

CT-1-/- mice are highly sensitive to Fas-mediated apoptosis due in part to deficient STAT-3 activation and inadequate control of calpain activity during the apoptotic process. Our data show that CT-1 is a natural defense of the liver against apoptosis. This cytokine may have therapeutic potential.

Circulating tumor cells (CTC) detection: clinical impact and future directions

Recent molecular and clinical studies have shown that invasion may occur very early in tumor development, thus emphasizing the potential importance of specific and sensitive detection of circulating tumor cells (CTC) and circulating tumor microemboli (CTM). The technical challenge in this field consists of finding "rare" tumor cells (just a few CTCs mixed with the approximately 10 million leukocytes and 5 billion erythrocytes in 1ml of blood) and being able to distinguish them from epithelial non-tumor cells and leukocytes. Many recent studies have discussed the clinical impact of detecting CTC/CTM. Although conflicting results have been obtained, these studies suggest the vast potential of CTC/CTM detection in cancer prognosis and follow up. However, the variable technical approaches which were used, as well as the number of millilitres of blood analyzed, the quality of sensitivity and specificity tests, the number of patients versus controls and the data interpretation make it very difficult to draw firm conclusions. A particularly important recent finding is that invasive tumor cells tend to loose their epithelial antigens by the epithelial to mesenchymal transition (EMT) process. Furthermore, it is known that non-tumor epithelial cells can also be present in blood. Thus, it appears that a reliable diagnostic identification of CTC and CTM cannot be based on the expression of epithelial-specific transcripts or antigens. Cytopathological examination of CTC/CTM, sensitively enriched from blood, represents a potentially useful alternative and can now be employed in routine analyses as a specific diagnostic assay, and be tested in large, blind, multicenter clinical trials. This basic approach can be complemented by immunological and molecular studies for further characterization of CTC/CTM and of their malignant potential. This review is aimed at helping oncologists critically evaluate past and future research work in this field. The interest in development and assessment of this noninvasive marker should lead to more effective and better tailored anticancer treatments for individual patients, thus resulting in their improved life expectancy.

Role of ischaemic preconditioning in liver regeneration following major liver resection and transplantation

Liver ischaemic preconditioning (IPC) is known to protect the liver from the detrimental effects of ischaemic-reperfusion injury (IRI), which contributes significantly to the morbidity and mortality following major liver surgery. Recent studies have focused on the role of IPC in liver regeneration, the precise mechanism of which are not completely understood. This review discusses the current understanding of the mechanism of liver regeneration and the role of IPC in this setting. Relevant articles were reviewed from the published literature using the Medline database. The search was performed using the keywords “liver”, “ischaemic reperfusion”, “ischaemic preconditioning”, “regeneration”, “hepatectomy” and “transplantation”. The underlying mechanism of liver regeneration is a complex process involving the interaction of cytokines, growth factors and the metabolic demand of the liver. IPC, through various mediators, promotes liver regeneration by up-regulating growth-promoting factors and suppresses growth-inhibiting factors as well as damaging stresses. The increased understanding of the cellular mechanisms involved in IPC will enable the development of alternative treatment modalities aimed at promoting liver regeneration following major liver resection and transplantation.

The response of the hepatocyte to ischemia

BACKGROUND

Ischemia-reperfusion (I/R) injury associated with hepatic resections and liver transplantation remains a serious complication in clinical practice, in spite of several attempts to solve the problem.

AIMS

To evaluate the response of the hepatocyte to ischemia

METHODS

Published data are thus revised.

RESULTS

The response of the hepatocyte to ischemia is based on the sensitivity of hepatocytes to different types of ischemia, the kind of cell death of the hepatocyte when it is subjected to ischemia, and on the response of the hepatocyte to the different times and extents of ischemia. Clinical factors including starvation, graft, age, and hepatic steatosis, all of which contribute to enhancing liver susceptibility to ischemia/reperfusion injury.

CONCLUSION

Ischemic preconditioning, based on the induction of a brief ischemia to the liver prior to a prolonged ischemia, has been applied in tumor hepatic resections for reducing hepatic I/R injury and recent clinical studies suggest that this surgical strategy could be appropriate for liver transplantation.

A prospective, randomized, controlled trial comparing intermittent portal triad clamping versus ischemic preconditioning with continuous clamping for major liver resection

OBJECTIVE

To evaluate whether ischemic preconditioning (IP) with continuous clamping or intermittent clamping (IC) of the portal triad confers better protection during liver surgery.

SUMMARY BACKGROUND DATA

IP and IC are distinct protective approaches against ischemic injury. Since both strategies proved to be superior in randomized controlled trials (RCTs) to continuous inflow occlusion alone, we designed a RCT to compare IP and IC in patients undergoing major liver resection.

METHODS

Noncirrhotic patients undergoing major liver resection were randomized to receive IP with inflow occlusion (n = 36) or IC (n = 37). Primary endpoints were postoperative liver injury and intraoperative blood loss. Postoperative liver injury was assessed by peak values of AST (alanine aminotransferase) and ALT (aspartate aminotransferase), as well as the area under the curve (AUC) of the postoperative transaminase course. Secondary endpoints included resection time, the need of blood transfusion, ICU, and hospital stay as well as postoperative complications and mortality.

RESULTS

Both groups were comparable regarding demographics, ASA score, type of hepatectomy, duration of inflow occlusion (range, 30-75 minutes), and resection surface. The transection-related blood loss was 146 versus 250 mL (P = 0.008), and when standardized to the resection surface 1.2 versus 1.8 mL/cm (P = 0.01) for IP and IC, respectively. Although peak AST, AUCAST, and AUCALT were lower for IC, the differences did not reach statistical significance. Overall (42% vs. 38%) and major (33 vs. 27%) postoperative complications as well as median ICU (1 vs. 1 day) and hospital stay (10 vs. 11 days) were similar between both groups.

CONCLUSIONS

Both IP and IC appear to be equally effective in protecting against postoperative liver injury in noncirrhotic patients undergoing major liver resection. However, IP is associated with lower blood loss and shorter transection time. Therefore, both strategies can be recommended for noncirrhotic patients undergoing liver resection.

The effects of oxidative stress on the liver and ileum in rats caused by one-lung ventilation

BACKGROUND AND AIM

Reactive oxygen radicals that cause remote organ injury are increased after the one-lung ventilation frequently used in thoracic surgery. The aim of this study was to examine the effects of one-lung ventilation on the liver and ileum.

MATERIALS AND METHODS

Thirty rats were divided into five groups: a sham group; 3- and 4-h mechanical ventilation groups; and 1- and 2-h left lung collapse/2-h re-expansion groups (n = 6 for each group). In the collapse groups, the left lung was collapsed by bronchial occlusion for 1 and 2 h and then re-expanded and ventilated for an additional 2 h. At the end of the study, serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were determined to assess liver functions. Myeloperoxidase (MPO) and malondialdehyde (MDA) activity were determined in the liver and ileum tissues. The tissues were also examined by light and electron microscope. Apoptosis was assessed using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) assay.

RESULTS

Plasma ALT and AST, tissue MDA, and MPO activities in both tissues were significantly higher in the 2-h collapse/2-h re-expansion group than in the 4-h mechanical ventilation group (P < 0.05). Moreover, the levels were significantly higher in the 2-h collapse group compared to the 1-h collapse group (P < 0.016). Tissue damage and apoptotic index were most prominent in the 2-h collapse/2-h re-expansion group.

CONCLUSION

Our findings showed that one-lung ventilation causes tissue damage in the liver and ileum and that this damage increases as occlusion duration rises.

Ischemic preconditioning reduces the severity of ischemia-reperfusion injury of peripheral nerve in rats

Background and aim

Allow for protection of briefly ischemic tissues against the harmful effects of subsequent prolonged ischemia is a phenomennon called as Ischemic Preconditioning (IP). IP has not been studied in ischemia-reperfusion (I/R) model of peripheral nerve before. We aimed to study the effects of acute IP on I/R injury of peripheral nerve in rats.

Method

70 adult male rats were randomly divided into 5 groups in part 1 experimentation and 3 groups in part 2 experimentation. A rat model of severe nerve ischemia which was produced by tying iliac arteries and all idenfiable anastomotic vessels with a silk suture (6-0) was used to study the effects of I/R and IP on nerve biochemistry. The suture technique used was a slip-knot technique for rapid release at time of reperfusion in the study. Cytoplasmic vacuolar degeneration was also histopathologically evaluated by light microscopic examination in sciatic nerves of rats at 7th day in part 2 study.

Results

3 hours of Reperfusion resulted in an increase in nerve malondialdehyde levels when compared with ischemia and non-ischemia groups (p < 0.001 and p < 0.0001 respectively). IP had significantly lower nerve MDA levels than 3 h reperfusion group (p < 0.001). The differences between ischemic, IP and non-ischemic control groups were not significant (p > 0.05). There was also a significant decrease in vacoular degeneration of sciatic nerves in IP group than I/R group (p < 0.05).

Conclusion

IP reduces the severity of I/R injury in peripheral nerve as shown by reduced tissue MDA levels at 3 th hour of reperfusion and axonal vacoulization at 7 th postischemic day.