Impact of Graft Steatosis on Postoperative Complications after Liver Transplantation.

Background Steatotic grafts are more susceptible to ischemia-reperfusion injury than are normal grafts. Therefore, using steatotic grafts for liver transplantation (LT) is associated with high primary dysfunction and decreased survival rates. The aim of this study is to evaluate the impact of graft steatosis on post LT outcomes. Methods A retrospective cohort analysis of 271 LT recipients from 2005 to 2016 was performed and patients were classified based on two types of steatosis, macrosteatosis (MaS), and microsteatosis (MiS). Each category was subdivided into three groups according to the degree of steatosis: no (< 5%), mild (≥5 to < 30%), and moderate (≥30 to ≤60%). The primary hospital stays and 6-month postoperative complications were analyzed by the Clavien-Dindo classification system. Additionally, patient and graft survivals were studied. Results Significant differences were observed in grade III MaS ( p -value = 0.019) and grade V MiS ( p -value = 0.020). A high trend of early graft dysfunction was found in the moderate MaS and MiS groups; however, they were not statistically significant ( p -value = 0.199 and 0.282, respectively). Interestingly, the acute cellular rejection (ACR) rate was found to be inversely proportional to the degree of steatosis in both categories but it did not reach a significant level ( p -value = 0.161 and 0.111, respectively). Conclusion Excellent post LT long-term outcomes using grafts with mild and moderate steatosis were determined. Further studies are needed to evaluate the newly proposed relationship between ACR and steatosis.

Low platelet counts after liver transplantation predict early posttransplant survival: the 60-5 criterion.

Platelets play a critical role in liver injury and regeneration. Thrombocytopenia is associated with increases in postoperative complications after partial hepatectomy, but it is unknown whether platelet counts could also predict outcomes after transplantation, a procedure that is often performed in thrombocytopenic patients. Therefore, the aim of this study was to evaluate whether platelet counts could be indicators of short- and long-term outcomes after liver transplantation (LT). Two hundred fifty-seven consecutive LT recipients (January 2003-December 2011) from our prospective database were analyzed. Preoperative and daily postoperative platelet counts were recorded until postoperative day 7 (POD7). Univariate and multivariate analyses were performed to assess whether low perioperative platelet counts were a risk factor for postoperative complications and graft and patient survival. The median pretransplant platelet count was 88 × 10(9) /L [interquartile range (IQR) = 58-127 × 10(9) /L]. The lowest platelet counts occurred on POD3: the median was 56 × 10(9) /L (IQR = 41-86 × 10(9) /L). Patients with low platelet counts on POD5 had higher rates of severe (grade IIIb/IV) complications [39% versus 29%, odds ratio (OR) = 1.09 (95% CI = 1.1-3.3), P = 0.02] and 90-day mortality [16% versus 8%, OR = 2.25 (95% CI = 1.0-5.0), P = 0.05]. In the multivariate analysis, POD5 platelet counts < 60 × 10(9) /L were identified as an independent risk factor for grade IIIb/IV complications [OR = 1.96 (95% CI = 1.07-3.56), P = 0.03)], graft survival [hazard ratio (HR) = 2.0 (95% CI = 1.1-3.6), P = 0.03)], and patient survival [HR = 2.2 (95% CI = 1.1-4.6), P = 0.03)]. The predictive value of platelet counts for graft and patient survival was lost in patients who survived 90 days. In conclusion, after LT, platelet counts < 60 × 10(9) /L on POD5 (the 60-5 criterion) are an independent factor associated with severe complications and early graft and patient survival. These findings may help us to develop protective strategies or specific interventions for high-risk patients.

Chemical composition of hepatic lipids mediates reperfusion injury of the macrosteatotic mouse liver through thromboxane A(2).

BACKGROUND & AIMS: Chemical composition of hepatic lipids is an evolving player in steatotic liver ischemia/reperfusion (I/R) injury. Thromboxane A(2) (TXA(2)) is a vasoactive pro-inflammatory lipid mediator derived from arachidonic acid (AA), an omega-6 fatty acid (Ω-6 FA). Reduced tolerance of the macrosteatotic liver to I/R may be related to increased TXA(2) synthesis due to the predominance of Ω-6 FAs. METHODS: TXA(2) levels elicited by I/R in ob/ob and wild type mice were assessed by ELISA. Ob/ob mice were fed Ω-3 FAs enriched diet to reduce hepatic synthesis of AA and TXA(2) or treated with selective TXA(2) receptor blocker before I/R. RESULTS: I/R triggered significantly higher hepatic TXA(2) production in ob/ob than wild type animals. Compared with ob/ob mice on regular diet, Ω-3 FAs supplementation markedly reduced hepatic AA levels before ischemia and consistently blunted hepatic TXA(2) synthesis after reperfusion. Sinusoidal perfusion and hepatocellular damage were significantly ameliorated despite downregulation of heme oxygenase-1. Hepatic transcript and protein levels of IL-1ß and neutrophil recruitment were significantly diminished after reperfusion. Moreover, TXA(2) receptor blockage conferred similar protection without modification of the histological pattern of steatosis. A stronger protection was achieved in the steatotic compared with lean animals. CONCLUSIONS: Enhanced I/R injury in the macrosteatotic liver is explained, at least partially, by TXA(2) mediated microcirculatory failure rather than size-related mechanical compression of the sinusoids by lipid droplets. TXA(2) blockage may be a simple strategy to include steatotic organs and overcome the shortage of donor organs for liver transplantation.

Activation of serotonin receptor-2B rescues small-for-size liver graft failure in mice.

UNLABELLED: The implantation of grafts below 30% of the normal liver volume is associated with a high risk of failure known as small-for-size (SFS) syndrome. Strategies to rescue small grafts may have a dramatic impact on organ shortage. Serotonin is a potent growth factor for the liver. The goal of this study was to determine whether enhanced serotonin signaling could prevent the deleterious effects of SFS syndrome. We performed 30% normal liver volume transplantations in wild-type C57/BL6 and interleukin-6 (IL-6)(-/-) mice. Some animals received α-methyl-5-HT (DOI), an agonist of serotonin receptor-2 (5-HT2B). Endpoints included long-term survival, serum and hepatic markers of liver injury and regeneration, assessment of hepatic microcirculation by intravital fluorescence microscopy and scanning electron microscopy, and transcript levels of a variety of serotonin receptors, tumor necrosis factor α, and IL-6. All recipients of small grafts (controls) died within 2-4 days of transplantation, whereas half of those receiving DOI survived permanently. Control animals disclosed major liver injury, including diffuse microvesicular steatosis in hepatocytes, impairment of microcirculation, and a failure of regeneration, whereas these parameters were dramatically improved in animals subjected to DOI. Blockage of 5-HT2B blunted the protective effects of DOI. Whereas IL-6 levels were higher in DOI-treated animals, IL-6(-/-) mice were still protected by DOI, suggesting a protective pathway independent of IL-6. CONCLUSION: Serotonin through its action on receptor-2B protects SFS liver grafts from injury and prevents microcirculation and regeneration. The mechanism of hepato-protection is independent of IL-6.

Liver transplantation using fatty livers: always feasible?

Steatotic liver grafts represent the most common type of "extended criteria" organs that have been introduced during the last two decades due to the disparity between liver transplant candidates and the number available organs. A precise definition and reliable and reproducible method for steatosis quantification is currently lacking and the potential influence of the chemical composition of hepatic lipids has not been addressed. In our view, these shortcomings appear to contribute significantly to the inconsistent results of studies reporting on graft steatosis and the outcome of liver transplantation. In this review, various definitions, prevalence and methods of quantification of liver steatosis will be covered. Ischemia/reperfusion injury of the steatotic liver and its consequences on post-transplant outcome will be discussed. Selection criteria for organ allocation and a number of emerging protective strategies are suggested.

Impact of preoperative bevacizumab on complications after resection of colorectal liver metastases: case-matched control study.

BACKGROUND: Chemotherapy may increase postoperative morbidity and mortality after liver surgery. Especially bevacizumab, a monoclonal antibody against vascular endothelial growth factor (VEGF), could have a detrimental effect. To assess the impact of neoadjuvant bevacizumab on clinical outcome after hepatectomy for colorectal liver metastases (CRLMs) this case-matched control study was initiated. METHODS: The multicentric data collection was performed in the Swiss HPB Center of the University Hospital Zurich (CH), the Department of Digestive Surgery and Transplantation Strasbourg (F), and the Division of Hepato-biliary-pancreatic surgery of "Josep Tureta" Hospital Girona (E). Consecutive patients operated onbetween July 2005 and December 2007 due to CRLMs who received neoadjuvant chemotherapy were assessed. Patients were divided in two groups: group A had neoadjuvant chemotherapy with bevacicumab, and group B had it without bevacizumab. RESULTS: No differences in overall morbidity (56 vs. 40% in the bevacizumab and control groups, respectively, p = 0.23) or mortality could be documented. Similarly, the incidence of severe postoperative complications was not statistically different between the bevacizumab and control groups (31 and 18%, respectively, p = 0.31). Wound complications were comparable (11% in the bevacizumab group compared and 9% in the control group, p = 1.00). However, bevacizumab was associated with a significantly decreased incidence of postoperative hepatic insufficiency (7 vs. 20%, p = 0.03). CONCLUSIONS: No impact on the incidence or severity of complications by bevacizumab could be shown. Bevacizumab may even reduce the incidence of liver failure after liver surgery.

Assessment of hepatic steatosis by expert pathologists: the end of a gold standard.

BACKGROUND: The presence of fat in the liver is considered a major risk for postoperative complication after liver surgery and transplantation. The current standard of quantification of hepatic steatosis is microscopic evaluation by pathologists, although consistency in such assessment remains unclear. Computerized image analysis is an alternative method for objective assessment of the degree of hepatic steatosis. METHODS: High resolution images of hematoxylin and eosin stained liver sections from 46 consecutive patients, initially diagnosed with liver steatosis, were blindly assessed by 4 established expert pathologists from different institutions. Computerized analysis was carried out simultaneously on the same sections. Interobserver agreement and correlation between the pathologists' and computerized assessment were evaluated using intraclass correlation coefficients (ICC), Spearman rank correlation coefficients, or descriptive statistics. RESULTS: Poor agreement among pathologists (ICC: 0.57) was found regarding the assessment of total steatosis, (ICC >0.7 indicates acceptable agreement). Pathologists' estimation of micro- and macrosteatosis disclosed also poor correlation (ICC: 0.22, 0.55, respectively). Inconsistent assessment of histological features of steatohepatitis (lobular inflammation, portal inflammation, hepatocyte ballooning, and Mallory hyaline) was documented. Poor conformity was also shown between the computerized quantification and ratings of 3 pathologists (Spearman rank correlation coefficients: 0.22, 0.82, 0.28, and 0.38). CONCLUSION: Quantification of hepatic steatosis in histological sections is strongly observer-dependent, not reproducible, and does not correlate with the computerized estimation. Current standards of assessment, previously published data and the clinical relevance of hepatic steatosis for liver surgery and transplantation must be challenged.

The effect of perfluorocarbon-based artificial oxygen carriers on tissue-engineered trachea.

The biological effect of the perfluorocarbon-based artificial oxygen carrier (Oxygent) was investigated in tissue-engineered trachea (TET) construction. Media supplemented with and without 10% Oxygent were compared in all assessments. Partial tissue oxygen tension (PtO(2)) was measured with polarographic microprobes; epithelial metabolism was monitored by microdialysis inside the TET epithelium perfused with the medium underneath. Chondrocyte-DegraPol constructs were cultured for 1 month with the medium before glycosaminoglycan assessment and histology. Tissue reaction of TET epithelial scaffolds immersed with the medium was evaluated on the chick embryo chorioallantoic membrane. Oxygent perfusion medium increased the TET epithelial PtO(2) (51.2 +/- 0.3 mm Hg vs. 33.4 +/- 0.3 mm Hg at 200 microm thickness; 12.5 +/- 0.1 mm Hg vs. 3.1 +/- 0.1 mm Hg at 400 microm thickness, p < 0.01) and decreased the lactate concentration (0.63 +/- 0.08 vs. 0.80 +/- 0.06 mmol/L, p < 0.05), lactate/pyruvate (1.87 +/- 0.26 vs. 3.36 +/- 10.13, p < 0.05), and lactate/glucose ratios (0.10 +/- 0.00 vs. 0.29 +/- 0.14, p < 0.05). Chondrocyte-DegraPol in Oxygent group presented lower glycosaminoglycan value (0.03 +/- 0.00 vs. 0.13 +/- 0.00, p < 0.05); histology slides showed poor acid mucopolysaccharides formation. Orthogonal polarization spectral imaging showed no difference in functional capillary density between the scaffolds cultured on chorioallantoic membranes. The foreign body reaction was similar in both groups. We conclude that Oxygent increases TET epithelial PtO(2), improves epithelial metabolism, does not impair angiogenesis, and tends to slow cartilage tissue formation.

Aggravation of viral hepatitis by platelet-derived serotonin.

More than 500 million people worldwide are persistently infected with hepatitis B virus or hepatitis C virus. Although both viruses are poorly cytopathic, persistence of either virus carries a risk of chronic liver inflammation, potentially resulting in liver steatosis, liver cirrhosis, end-stage liver failure or hepatocellular carcinoma. Virus-specific T cells are a major determinant of the outcome of hepatitis, as they contribute to the early control of chronic hepatitis viruses, but they also mediate immunopathology during persistent virus infection. We have analyzed the role of platelet-derived vasoactive serotonin during virus-induced CD8(+) T cell-dependent immunopathological hepatitis in mice infected with the noncytopathic lymphocytic choriomeningitis virus. After virus infection, platelets were recruited to the liver, and their activation correlated with severely reduced sinusoidal microcirculation, delayed virus elimination and increased immunopathological liver cell damage. Lack of platelet-derived serotonin in serotonin-deficient mice normalized hepatic microcirculatory dysfunction, accelerated virus clearance in the liver and reduced CD8(+) T cell-dependent liver cell damage. In keeping with these observations, serotonin treatment of infected mice delayed entry of activated CD8(+) T cells into the liver, delayed virus control and aggravated immunopathological hepatitis. Thus, vasoactive serotonin supports virus persistence in the liver and aggravates virus-induced immunopathology.

Selective portal vein embolization and ligation trigger different regenerative responses in the rat liver.

UNLABELLED: Two strategies are clinically available to induce selective hypertrophy of the liver: portal vein embolization (PVE) and portal vein ligation (PVL). The aim of this study was to compare the impact of PVE and PVL on liver regeneration. Rats were subjected to 70% PVL, 70% PVE, 70% partial hepatectomy (PH) (positive control), or sham operation (negative control). PVL and PVE of liver segments were validated by portography and histology, demonstrating obstruction of the involved portal branches. Liver weight and markers of regeneration were assessed at 24, 48, and 72 hours, and 7 days after surgery (n = 5). Sinusoidal perfusion was examined by intravital microscopy. The weight of the regenerating liver segments increased continuously in all groups, with the highest weight gain after PH, which also disclosed the strongest proliferative activity. In Ki-67 and PCNA stainings, hepatocyte proliferation after PVL was more pronounced than after PVE (P = 0.01). Volumetric blood flow and functional sinusoidal density were lower after PVE than after PVL (P = 0.006, P = 0.02, respectively). The accumulation of Kupffer cells 24 hours after the intervention was highest after PH. Transcript levels of cytokines (interleukin-1beta, tumor necrosis factor-alpha, interleukin-6) peaked at 24 hours and were highest after PH. The embolized part of the liver after PVE showed prominent foreign body reaction in the portal triad with accumulation of macrophages. CONCLUSION: PVL is superior to PVE in inducing a regenerative response of the remnant liver. The impairment of liver regeneration after PVE may be a consequence of macrophage trapping in the occluded segment due to a foreign body reaction. Lower blood flow and lower accumulation of macrophages, particularly Kupffer cells, in the regenerating part of the liver likewise causes impaired liver regeneration after PVE.

Omega 3 - Omega 6: What is right for the liver?

Linoleic and alpha-linolenic acids are the fatty acids designated as "essential" since they are not synthesized by mammalian cells and must be provided in the diet. The recent dietary shift towards the consumption of n-6 (omega-6) at the expense of n-3 (omega-3) polyunsaturated fatty acids (PUFAs) is thought to be a primary cause of many diseases related to the Western diet. The body converts linoleic acid to arachidonic acid and derives eicosapentaenoic acid from alpha-linolenic acid. Ideally the effects of these fatty acids and their eicosanoid derivatives are tailored to the specific biological needs of the body. The balance between n-3 and n-6 PUFAs is essential for metabolism and maintenance of the functions of both classes. The availability of n-3 long chain PUFAs plays a major role in regulating both fat accumulation and its elimination by the liver. Derangement of hepatic n-6:n-3 PUFA ratio impacts on the histological pattern of fatty liver through modulation of the amount of intrahepatic lipids. Moreover, the influence of PUFAs and their eicosanoid products on hepatic microcirculation and ischemia/reperfusion injury has been demonstrated in many studies. This concise review article will focus on the role of PUFAs and eicosanoids in hepatic steatosis, microcirculation and ischemia/reperfusion injury.

Prevention of reperfusion injury and microcirculatory failure in macrosteatotic mouse liver by omega-3 fatty acids.

UNLABELLED: Macrovesicular hepatic steatosis has a lower tolerance to reperfusion injury than microvesicular steatosis with an abnormally high ratio of omega-6 (n-6): omega-3 (n-3) polyunsaturated fatty acids (PUFAs). We investigated the influence of PUFAs on microcirculation in steatotic livers and the potential to minimize reperfusion injury in the macrosteatotic liver by normalization of PUFAs. Ob/ob mice were used as a model of macrovesicular hepatic steatosis and C57/Bl6 mice fed a choline-deficient diet for microvesicular steatosis. Steatotic and lean livers were subjected to 45 minutes of ischemia and 3 hours of reperfusion. Hepatic content of omega-3 and omega-6 PUFAs was determined. Microcirculation was investigated using intravital fluorescence microscopy. A second group of ob/ob mice was supplemented with dietary omega-3 PUFAs and compared with the control diet-fed group. Microcirculation, AST, and Kupffer cell activity were assessed. Macrosteatotic livers had significant microcirculatory dysfunction correlating with high omega-6: omega-3 PUFA ratio. Dietary omega-3 PUFA resulted in normalization of this ratio, reduction of intrahepatic lipids, and decrease in the extent of macrosteatosis. Defective microcirculation was dramatically ameliorated with significant reduction in Kupffer cell activity and protection against hepatocellular injury both before ischemia and after reperfusion. CONCLUSION: Macrosteatotic livers disclosed an abnormal omega-6: omega-3 PUFA ratio that correlates with a microcirculatory defect that enhanced reperfusion injury. Thus, protective strategies applied during or after ischemia are unlikely to be useful. Preoperative dietary omega-3 PUFAs protect macrosteatotic livers against reperfusion injury and might represent a valuable method to expand the live liver donor pool.