Steatotic Liver Transplantation Research Articles

Similar outcome after transplantation of moderate macrovesicular steatotic and nonsteatotic livers when the cold ischemia time is kept very short.

Livers with moderate (30-60%) macrovesicular steatosis have been associated with poor outcome after transplantation. Aim of this study was to examine the outcome after transplantation of livers with moderate macrovesicular steatosis when the cold ischemia time (CIT) is kept very short. Postoperative outcome of 19 recipients of a moderate steatotic liver were compared with a matched control group of 95 recipients of a nonsteatotic liver graft (1:5 ratio). We studied graft/patient survival rates, incidences of primary nonfunction, postoperative complications (classified according to the Clavien-Dindo classification), first-week postoperative hepatic injury serum markers (AST/ALT), and liver function tests (PT time/bilirubin/lactate). In addition, we studied reversal of graft steatosis in follow-up biopsies. Median CIT in livers with moderate steatosis and in controls was below 8h in both groups. Although short- and long-term patient/graft survival rates and results of liver function tests were similar, serum markers of hepatic injury and postoperative complications (especially grade IVa) were significantly higher in recipients of a moderate steatotic liver. Reversal of steatosis was seen in 9 of the 11 (82%) recipients with follow-up liver biopsies. Despite the association with severe postoperative complications, moderate macrovesicular steatotic livers can be used successfully for transplantation if the CIT is kept very short.

The effect of brain death in rat steatotic and non-steatotic liver transplantation with previous ischemic preconditioning

Most liver grafts undergoing transplantation derive from brain dead donors, which may also show hepatic steatosis, being both characteristic risk factors in liver transplantation. Ischemic preconditioning shows benefits when applied in non-brain dead clinical situations like hepatectomies, whereas it has been less promising in the transplantation from brain dead patients. This study examined how brain death affects preconditioned steatotic and non-steatotic liver grafts undergoing transplantation. Steatotic and non-steatotic grafts from non-brain dead and brain dead-donors were cold stored for 6h and then transplanted. After 2, 4, and 16 h of reperfusion, hepatic damage was analysed. In addition, two therapeutic strategies, ischemic preconditioning and/or acetylcholine pre-treatment, and their underlying mechanisms were characterized. Preconditioning benefits in non-brain dead donors were associated with nitric oxide and acetylcholine generation. In brain dead donors, preconditioning generated nitric oxide but did not promote acetylcholine upregulation, and this resulted in inflammation and damage. Acetylcholine treatment in brain dead donors, through PKC, increased antioxidants and reduced lipid peroxidation, nitrotyrosines and neutrophil accumulation, altogether protecting against damage. The combination of acetylcholine and preconditioning conferred stronger protection against damage, oxidative stress and neutrophil accumulation than acetylcholine treatment alone. These superior beneficial effects were due to a selective preconditioning-mediated generation of nitric oxide and regulation of PPAR and TLR4 pathways, which were not observed when acetylcholine was administered alone. Our findings propose the combination of acetylcholine+preconditioning as a feasible and highly protective strategy to reduce the adverse effects of brain death and to ultimately improve liver graft quality.

Adiponectin and resistin protect steatotic livers undergoing transplantation

Numerous steatotic livers are discarded for transplantation because of their poor tolerance to ischemia-reperfusion. Controversial roles for adiponectin and related adipocytokines visfatin and resistin have been described in different liver pathologies, nevertheless it is unknown their possible implication in ischemia-reperfusion injury associated with liver transplantation. Our study aimed at characterizing the role of the adiponectin-derived molecular pathway in transplantation with steatotic and non-steatotic liver grafts. Steatotic and non-steatotic liver transplantation was carried out and the hepatic levels of adiponectin, visfatin and resistin were measured and modulated either pharmacologically or surgically. Steatotic liver grafts exhibited downregulation of both adiponectin and resistin when subjected to transplantation. Adiponectin pre-treatment only protected steatotic grafts and did it so through a visfatin-independent and resistin-dependent mechanism. Adiponectin-derived resistin accumulation activated the PI3K/Akt pathway, unravelling AMPK as an upstream mediator of adiponectin's actions in steatotic grafts. Strategies aimed at increasing adiponectin including either AMPK activators or the induction of ischemic preconditioning (which activates AMPK) increased resistin accumulation, prevented the downregulation of PI3K/Akt pathway and protected steatotic liver grafts. Conversely, PI3K/Akt pathway upregulation and hepatic protection induced by adiponectin were abolished when resistin action was inhibited. Our findings reveal a new protective pathway in steatotic liver transplantation, namely AMPK-adiponectin-resistin-PI3K/Akt, which may help develop new strategies aimed at increasing either adiponectin or resistin in the steatotic liver undergoing transplant to ultimately increase organ donor pool and reduce waiting list.

Proteasome inhibitors protect the steatotic and non-steatotic liver graft against cold ischemia reperfusion injury

BackgroundThe dramatic shortage of organs leads to consider the steatotic livers for transplantation although their poor tolerance against ischemia reperfusion injury (IRI). Ubiquitin proteasome system (UPS) inhibition during hypothermia prolongs myocardial graft preservation. The role of UPS in the liver IRI is not fully understood. Bortezomib (BRZ) treatment at non-toxic doses of rats fed alcohol chronically has shown protective effects by increasing liver antioxidant enzymes. We evaluated and compared both proteasome inhibitors BRZ and MG132 in addition to University of Wisconsin preservation solution (UW) at low and non-toxic dose for fatty liver graft protection against cold IRI. ExperimentalSteatotic and non-steatotic livers have been stored in UW enriched with BRZ (100nM) or MG132 (25μM), for 24h at 4°C and then subjected to 2-h normothermic reperfusion (37°C). Liver injury (AST/ALT), hepatic function (bile output; vascular resistance), mitochondrial damage (GLDH), oxidative stress (MDA), nitric oxide (NO) (e-NOS activity; nitrates/nitrites), proteasome chymotrypsin-like activity (ChT), and UPS (19S and 20S5 beta) protein levels have been measured. ResultsChT was inhibited when BRZ and MG132 were added to UW. Both inhibitors prevented liver injury (AST/ALT), when compared to UW alone. BRZ increased bile production more efficiently than MG132. Only BRZ decreased vascular resistance in fatty livers, which correlated with an increase in NO generation (through e-NOS activation) and AMPK phosphorylation. GLDH and MDA were also prevented by BRZ. In addition, BRZ inhibited adiponectin, IL-1, and TNF alpha, only in steatotic livers. ConclusionMG132 and BRZ, administrated at low and non toxic doses, are very efficient to protect fatty liver grafts against cold IRI. The benefits of BRZ are more effective than those of MG132. This evidenced for the first time the potential use of UPS inhibitors for the preservation of marginal liver grafts and for future applications in the prevention of IRI.

Tauroursodeoxycholic Acid Affects PPARγ and TLR4 in Steatotic Liver Transplantation

Numerous steatotic livers are discarded for transplantation because of their poor tolerance to ischemia-reperfusion (I/R). We examined whether tauroursodeoxycholic acid (TUDCA), a known inhibitor of endoplasmic reticulum (ER) stress, protects steatotic and nonsteatotic liver grafts preserved during 6 h in University of Wisconsin (UW) solution and transplanted. The protective mechanisms of TUDCA were also examined. Neither unfolded protein response (UPR) induction nor ER stress was evidenced in steatotic and nonsteatotic liver grafts after 6 h in UW preservation solution. TUDCA only protected steatotic livers grafts and did so through a mechanism independent of ER stress. It reduced proliferator-activated receptor-γ (PPARγ) and damage. When PPARγ was activated, TUDCA did not reduce damage. TUDCA, which inhibited PPARγ, and the PPARγ antagonist treatment up-regulated toll-like receptor 4 (TLR4), specifically the TIR domain-containing adaptor inducing IFNβ (TRIF) pathway. TLR4 agonist treatment reduced damage in steatotic liver grafts. When TLR4 action was inhibited, PPARγ antagonists did not protect steatotic liver grafts. In conclusion, TUDCA reduced PPARγ and this in turn up-regulated the TLR4 pathway, thus protecting steatotic liver grafts. TLR4 activating-based strategies could reduce the inherent risk of steatotic liver failure after transplantation.

Generation of a Recombinant Heme Oxygenase, Delivered by Cell-Penetrating Peptides, to Protect Transplanted Steatotic Livers from Reperfusion Injury

Objective: To assay the ability of a cell-penetrating heme oxygenase-1 (HO-1) protein to protect organs from ischemia-reperfusion injury in models of steatotic liver transplantation. Methods: Plasmid constructs expressing cell-penetrating enhanced green fluorescent protein (CPP-EGFP) and HO-1 (CPP-HO-1) were generated by polymerase chain reaction amplification and ligation into a bacterial protein expression system. CPP-HO-1 and CPP-EGFP proteins were isolated from bacterial cultures and purified on nickel agarose columns. HO1-CPP functionality was assayed using spectrophometric quantification of bilirubin production by CPP-HO-1 treated HEK293T cells supplemented with the necessary co-factors. Cell penetration, in vitro, was assayed after treatment of various cell lines with CPP-tagged proteins in tissue culture and visualisation of target proteins by immunohistochemistry followed by fluorescence microscopy. Cellular internalisation of protein in rat livers was performed by ex vivo portal vein perfusion of isolated organs with 2mg of CPP-HO-1 or CPP-EGFP in histidine-tryptophan-ketoglutarate solution. Controls included mock treated organs and organs perfused with proteins lacking a CPP. To measure IRI we assayed for damage-associated molecular patterns (DAMPs) associated with oxidative stress such as mitochondrial DNA (mtDNA) by quantitative PCR. Results: Purified CPP-HO-1 is functional in a biochemical assay of bilirubin production and is able to penetrate cells in vitro. Histological analysis showed cell penetration of CPP-fused proteins in cells surrounding the hepatic portal vein after ex vivo perfusion, but not control proteins. mtDNA was detected in assays for DAMPs in models for IRI and has potential to be used as a marker for protection from IRI. Conclusions: We have successfully generated a CPP-HO-1 protein which is fully functional and is able to penetrate cells in vitro and ex vivo. Further work will determine if 1) CPP-HO-1 can provide cellular protection in an in vitro model of IRI 2) whether treatment of steatotic livers with CPP-HO-1 in a rat model of transplantation can protect these organs from IRI.

ICAM-1 Upregulation in Ethanol-Induced Fatty Murine Livers Promotes Injury and Sinusoidal Leukocyte Adherence after Transplantation

Background. Transplantation of ethanol-induced steatotic livers causes increased graft injury. We hypothesized that upregulation of hepatic ICAM-1 after ethanol produces increased leukocyte adherence, resulting in increased generation of reactive oxygen species (ROS) and injury after liver transplantation (LT). Methods. C57BL/6 wildtype (WT) and ICAM-1 knockout (KO) mice were gavaged with ethanol (6 g/kg) or water. LT was then performed into WT recipients. Necrosis and apoptosis, 4-hydroxynonenal (4-HNE) immunostaining, and sinusoidal leukocyte movement by intravital microscopy were assessed. Results. Ethanol gavage of WT mice increased hepatic triglycerides 10-fold compared to water treatment (P < 0.05). ICAM-1 also increased, but ALT was normal. At 8 h after LT of WT grafts, ALT increased 2-fold more with ethanol than water treatment (P < 0.05). Compared to ethanol-treated WT grafts, ALT from ethanol-treated KO grafts was 78% less (P < 0.05). Apoptosis also decreased by 75% (P < 0.05), and 4-HNE staining after LT was also decreased in ethanol-treated KO grafts compared to WT. Intravital microscopy demonstrated a 2-fold decrease in leukocyte adhesion in KO grafts compared to WT grafts. Conclusions. Increased ICAM-1 expression in ethanol-treated fatty livers predisposes to leukocyte adherence after LT, which leads to a disturbed microcirculation, oxidative stress and graft injury.

When GLP-1 hits the liver: a novel approach for insulin resistance and NASH

nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum ranging from simple steatosis to steatohepatitis (NASH), increasing fibrosis and eventually, cirrhosis ([22][1]). Importantly, NASH accompanied by fibrosis and severe inflammation is the most relevant predictor for disease progression

Ischemia–reperfusion injury in rat steatotic liver is dependent on NFκB P65 activation

BackgroundSteatotic liver grafts tolerate ischemia–reperfusion (I/R) injury poorly, contributing to increased primary graft nonfunction following transplantation. Activation of nuclear factor kappa-B (NFκB) following I/R injury plays a crucial role in activation of pro-inflammatory responses leading to injury. MethodsWe evaluated the role of NFκB in steatotic liver injury by using an orthotopic liver transplant (OLT) model in Zucker rats (lean to lean or obese to lean) to define the mechanisms of steatotic liver injury. Obese donors were treated with bortezomib to assess the role of NF-κB in steatotic liver I/R injury. Hepatic levels of NF-κB and pro-inflammatory cytokines were analyzed by ELISA. Serum transaminase levels and histopathological analysis were performed to assess associated graft injury. ResultsI/R injury in steatotic liver results in significant increases in activation of NF-κB (40%, p<0.003), specifically the p65 subunit following transplantation. Steatotic donor pretreatment with proteasome inhibitor bortezomib (0.1mg/kg) resulted in significant reduction in levels of activated NF-κB (0.58±0.18 vs. 1.37±0.06O.D./min/10μg protein, p<0.003). Bortezomib treatment also reduced expression of pro-inflammatory cytokines MIP-2 compared with control treated steatotic and lean liver transplants respectively (106±17.5 vs. 443.3±49.9 vs. 176±10.6pg/mL, p=0.02), TNF-α (223.8±29.9 vs. 518.5±66.5 vs. 264.5±30.1pg/2μg protein, p=0.003) and IL-1β (6.0±0.91 vs. 19.8±5.2 vs. 5±1.7pg/10μg protein, p=0.02) along with a significant reduction in ALT levels (715±71 vs. 3712.5±437.5 vs. 606±286U/L, p=0.01). ConclusionThese results suggest that I/R injury in steatotic liver transplantation are associated with exaggerated activation of NFκB subunit p65, leading to an inflammatory mechanism of reperfusion injury and necrosis. Proteasome inhibition in steatotic liver donor reduces NFκB p65 activation and inflammatory I/R injury, improving transplant outcomes of steatotic grafts in a rat model.

Hepatic Steatosis and Normothermic Perfusion—Preliminary Experiments in a Porcine Model

Steatotic livers are increasingly common in the donor population. Cold storage of steatotic livers exacerbates ischemia-reperfuson injury and risks primary nonfunction and recipient death. Normothermic preservation avoids prolonged cooling of the organ and may be well suited to the preservation and resuscitation of damaged livers. By ex vivo normothermic perfusion, it may be possible to preserve and improve steatotic livers, so that transplantation is a viable option. In a porcine model, streptozotocin was used to induce a hyperglycemic, ketotic state that, together with a high fat diet, resulted in mild hepatic steatosis at 5 weeks. A blood-based oxygenated ex vivo normothermic preservation system was then used to compare extended preservation of normal and mildly steatotic porcine livers at physiological pressures and flows. Serial liver biopsies were stained with Oil Red O, a specialist triglyceride stain, and were analyzed using custom-designed image analysis to quantify the degree of lipid deposition. Steatotic livers were capable of correcting the perfusate base excess and maintaining factor V and bile production and showed markers of liver injury comparable with normal livers. Steatotic livers had a significantly higher urea production and required no glucose support. Preliminary results suggest that prolonged normothermic perfusion results in a reduction in steatosis. This study suggests that steatotic livers can be successfully preserved using normothermic preservation for prolonged periods and that normothermic preservation facilitates a reduction in hepatic steatosis. Further studies are now needed including transplantation of steatotic livers after normothermic preservation.

Retinol-Binding Protein 4 and Peroxisome Proliferator-Activated Receptor-γ in Steatotic Liver Transplantation

Numerous steatotic livers are discarded for transplantation because of their poor tolerance of ischemia-reperfusion (I/R). The injurious effects of retinol-binding protein 4 (RBP4) in various pathologies are well documented. RBP4 levels are reduced by peroxisome proliferator-activated receptor-γ (PPARγ) agonists. Strategies aimed at increasing PPARγ protect steatotic livers under warm ischemia. Ischemic preconditioning (PC) based on brief periods of I/R protects steatotic liver grafts against I/R injury, but the responsible mechanism is poorly understood. We examined the roles of RBP4 and PPARγ in I/R injury associated with steatotic liver transplantation and the benefits of PC in such situations. We report that RBP4 and PPARγ expression levels in nonsteatotic livers were similar to those found in the sham group. However, reduced RBP4 and increased PPARγ levels were observed in steatotic livers. Treatment with either RBP4 or a PPARγ antagonist was effective only in steatotic livers. PC, which increased RBP4 levels, and RBP4 treatment both reduced PPARγ levels and hepatic injury in steatotic livers. When PPARγ was activated, neither RBP4 treatment nor PC (despite RBP4 induction) protected steatotic livers. In conclusion, steatotic liver grafts are more predisposed to down-regulate RBP4 and overexpress PPARγ. RBP4 treatment and PC, through RBP4 induction, reduced PPARγ levels in steatotic liver grafts, thus protecting them from the PPARγ detrimental effects.

Endoplasmic reticulum stress is a mediator of posttransplant injury in severely steatotic liver allografts

Hepatic steatosis continues to present a major challenge in liver transplantation. These organs have been shown to have increased susceptibility to cold ischemia/reperfusion (CIR) injury in comparison with otherwise comparable lean livers; the mechanisms governing this increased susceptibility to CIR injury are not fully understood. Endoplasmic reticulum (ER) stress is an important link between hepatic steatosis, insulin resistance, and metabolic syndrome. In this study, we investigated ER stress signaling and blockade in the mediation of CIR injury in severely steatotic rodent allografts. Steatotic allografts from genetically leptin-resistant rodents had increased ER stress responses and increased markers of hepatocellular injury after liver transplantation into strain-matched lean recipients. ER stress response components were reduced by the chemical chaperone taurine-conjugated ursodeoxycholic acid (TUDCA), and this resulted in an improvement in the allograft injury. TUDCA treatment decreased nuclear factor kappa B activation and the proinflammatory cytokines interleukin-6 and interleukin-1β. However, the predominant response was decreased expression of the ER stress cell death mediator [CCAAT/enhancer-binding protein homologous protein (CHOP)]. Furthermore, activation of inflammation-associated caspase-11 was decreased, and this linked ER stress/CHOP to proinflammatory cytokine production after steatotic liver transplantation. These data confirm ER stress in steatotic allografts and implicate this as a mediating mechanism of inflammation and hepatocyte death in the steatotic liver allograft.

Cyclic AMP in rat steatotic liver transplantation

Numerous steatotic livers are discarded as unsuitable for transplantation (TR) because of their poor tolerance of ischemia/reperfusion (I/R). Cyclic adenosine 3',5'-monophosphate (cAMP)-elevating agents protect against I/R injury both in nonsteatotic livers that have been removed from non-heart-beating donors and subjected to warm ischemia or cold ischemia (CIS) and in perfused, isolated livers. Ischemic preconditioning (PC), which is based on brief periods of I/R, protects steatotic liver grafts, but the mechanism that is responsible is poorly understood. This study examines the role of cAMP in the vulnerability shown by steatotic livers to TR-associated I/R injury and the benefits of PC in this situation. Steatotic livers with or without PC were transplanted into Zucker rats. The hepatic levels of cAMP were measured and altered pharmacologically. Our results indicate that the cAMP levels in the nonsteatotic liver grafts were similar to those found in a sham group. However, high cAMP levels were observed in steatotic liver grafts. The blockage of cAMP generation by adenylate cyclase inhibitor pre-treatment or PC had the following results: reduced hepatic injury and increased survival of steatotic graft recipients; greater preservation of adenosine triphosphate (ATP) and reduced lactate accumulation throughout CI. This blockade of cAMP by a nitric oxide-dependent mechanism protected steatotic liver grafts against oxidative stress and microvascular disorders after reperfusion. In conclusion, cAMP blocking-based strategies could protect patients against the inherent risk of steatotic liver failure after TR.

Does adiponectin benefit steatotic liver transplantation?

Strategies for improving the viability of steatotic donor livers could increase the number of organs suitable for transplantation. There is evidence that adiponectin, the most abundant adipose-specific adipokine, acts as an anti-obesity and anti-inflammatory hormone. Here we review the signaling pathways of adiponectin and the possible therapies based on adiponectin regulation that have been examined or applied clinically. Recent studies on the role of adiponectin in steatotic livers subjected to ischemia/reperfusion are discussed. The data suggest that further investigations are required to determine whether adiponectin is a potential therapeutic target in liver transplantation.

GSH Attenuates Organ Injury and Improves Function after Transplantation of Fatty Livers

Ischemia-reperfusion injury (IRI) is increased after transplantation of steatotic livers. Since those livers are increasingly used for transplantation, protective strategies must be developed. Reactive oxygen species (ROS) play a key role in hepatic IRI. In lean organs, glutathione (GSH) is an efficient scavenger of ROS, diminishing IRI. The aim of this study was to evaluate whether GSH also protects steatotic allografts from IRI following transplantation. Fatty or lean livers were explanted from 10-week-old obese or lean Zucker rats and preserved (obese 4 h, lean 24 h) in hypothermic University of Wisconsin solution. Arterialized liver transplantation was then performed in lean syngeneic Zucker rats. Recipients of fatty livers were treated with GSH (200 µmol/h/kg) or saline during reperfusion (2 h, n = 5). Parameters of hepatocellular damage and bile flow were measured. Transplantation of steatotic livers enhanced early reperfusion injury compared to lean organs as measured by increased aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase plasma levels. Bile flow was also reduced in steatotic grafts. Intravenous administration of GSH effectively decreased liver damage in fatty allografts and resulted in improved bile flow. Intravenous application of GSH effectively reduces early IRI in steatotic allografts and improves recovery of these marginal donor organs following transplantation.

Short- and Long-term Outcomes After Steatotic Liver Transplantation

To determine if the use of steatotic grafts adversely affects outcomes in liver transplantation. A retrospective review of a prospectively maintained database. A single center. Four hundred ninety adults who underwent liver transplantation from January 1, 2002, to December 31, 2008, at a single center. Graft biopsies were available in 310 (63.3%) cases. Grafts were classified based on amount of macrovesicular steatosis: 5% or less (n = 222), more than 5% to less than 35% (n = 66), and 35% or more (n = 22). Recipient demographics, Model for End-Stage Liver Disease (MELD) score, patient/graft survival, complications, transfusion rates, and liver function test results. One-, 3-, and 5-year patient and graft survivals, respectively, were similar (90.38%, 84.7%, and 74.4%, respectively, P = .3; and 88.7%, 82.5%, and 73.3%, respectively, P = .15). Median follow-up was 25 months. Recipient age, sex, body mass index, laboratory MELD score, and ischemia times were similar among all groups. Packed red blood cell (3 vs 8 U, P < .001), fresh frozen plasma (2 vs 4 U, P = .007), and cryoprecipitate transfusion rates were significantly increased in grafts with 35% or more steatosis. Intensive care unit (5 vs 11 days, P = .02) and hospital (11 vs 21 days, P < .001) stay was also increased in those with grafts with 35% or more steatosis compared with those with 5% or less steatosis. The grafts with 35% or more steatosis had higher transaminase peaks and longer times for bilirubin to normalize (P < .001). Use of carefully selected steatotic grafts was not associated with higher rates of primary nonfunction or poorer outcomes. However, the use of steatotic grafts is associated with increased resource use in the perioperative period.

C-Terminal Peptide of Anaphylatoxin C3a Enhances Hepatic Function After Steatotic Liver Transplantation: A Study in a Rat Model

BackgroundC3a, a complement component stimulates hepatocyte proliferation. In this study, we investigated whether a functional peptide from its C terminal, YAAALGLAR (C3aP), enhanced liver function after steatotic liver transplantation in a rat model. MethodsLivers of Sprague-Dawley (SD) rats fed a high-fat diet for 2 months were used as donors. Their liver parenchyma displayed over 60% macrovesicular steatosis upon histopathologic examination. Weight and age-matched isogeneic SD rats were used as recipients of orthotopic liver transplantations (OLTs). Before OLT, the donor livers were perfused with University of Wisconsin solution supplemented with 10 mg/L C3aP. Postoperatively, 0.1 mL of 100 μg/mL C3aP was administered daily intraperitoneally to the experimental group. Recipients without C3aP intraperitoneal administration were the control group. We examined the survival rates, histopathologic changes, and hepatic functions of recipients. ResultsSix of the 10 control recipients died within 3 days posttransplantation; however, among the experimental group, 8 of 10 recipients survived beyond 7 days. Histopathologic examination showed that at day 3 posttransplantation, hepatocyte steatosis was notably reversed in the experimental group with cells undergoing active mitosis. In contrast, massive parenchymal necrosis was observed among the control group without notable hepatocyte proliferation. Furthermore, serum enzyme levels among the experimental group were significantly lower than those of the control group at day 3 postoperatively. ConclusionC3aP stimulated hepatocyte proliferation and reversed fatty degradation of hepatocytes, thus enhancing hepatic function and prolonging the survival of recipients of steatotic liver transplantations.

Fibronectin-α4β1 Integrin Interactions Regulate Metalloproteinase-9 Expression in Steatotic Liver Ischemia and Reperfusion Injury

Ischemia/reperfusion injury is a major cause of the highly dysfunctional rate observed in marginal steatotic orthotopic liver transplantation. In this study, we document that the interactions between fibronectin, a key extracellular matrix protein, and its integrin receptor alpha4beta1, expressed on leukocytes, specifically up-regulated the expression and activation of metalloproteinase-9 (MMP-9, gelatinase B) in a well-established steatotic rat liver model of ex vivo ice-cold ischemia followed by isotransplantation. The presence of the active form of MMP-9 was accompanied by massive intragraft leukocyte infiltration, high levels of proinflammatory cytokines, such as interleukin-1beta and tumor necrosis factor-alpha, and impaired liver function. Interestingly, MMP-9 activity in steatotic liver grafts was, to a certain extent, independent of the expression of its natural inhibitor, the tissue inhibitor of metalloproteinases-1. Moreover, the blockade of fibronectin-alpha4beta1-integrin interactions inhibited the expression/activation of MMP-9 in steatotic orthotopic liver transplantations without significantly affecting the expression of metalloproteinase-2 (MMP-2, gelatinase A). Finally, we identified T lymphocytes and monocytes/macrophages as major sources of MMP-9 in steatotic liver grafts. Hence, these findings reveal a novel aspect of the function of fibronectin-alpha4beta1 integrin interactions that holds significance for the successful use of marginal steatotic livers in transplantation.

Adenosine monophosphate-activated protein kinase and nitric oxide in rat steatotic liver transplantation

Adenosine monophosphate-activated protein kinase and nitric oxide in rat steatotic liver transplantation

Synergistic Effects of Brain Death and Liver Steatosis on the Hepatic Microcirculation

The routine transplantation of steatotic livers could potentially mitigate the donor shortage, but so far is associated with a high rate of graft dysfunction. Steatosis and brain death have been perceived as independent risk factors, but they may synergistically target the hepatic microcirculation. This study compares the effects of brain death on the microcirculation of steatotic and normal livers. Brain death was induced in obese and lean Zucker rats. Lean and obese sham-operated animals served as controls. Liver microcirculation was investigated using intravital fluorescence microscopy. Serum liver enzyme and reduced glutathione, expression of P-selectin, ICAM-1 and VCAM-1 mRNA in the liver were determined. The ultrastructural alterations were compared by electron microscopy. In nonbrain-dead animals, liver steatosis was associated with smaller sinusoidal diameters, but did not impair sinusoidal perfusion. During brain death, sinusoidal diameter and perfusion were reduced in normal and, to a greater extent, in steatotic livers. Also, more leukocytes were recruited to the microvasculature of steatotic livers than to normal livers in brain-dead state. The highest liver enzyme activities and the lowest hepatic GSH concentrations were measured in brain-dead animals with steatotic livers; only in these organs was endothelial cell swelling regularly observed. In brain-dead state, only the P-selectin mRNA expression was increased in steatotic livers as compared to normal livers. Brain death amplifies the adverse effects of steatosis on the hepatic microcirculation. Our results underline the need for therapeutic intervention in brain-dead state when steatotic livers are to be used for transplantation.