Assessment and Transplantation of Orphan Donor Livers: A Back-to-Base Approach to Normothermic Machine Perfusion.

Globally, a large proportion of donor livers are discarded due to concerns over inadequate organ quality. Normothermic machine perfusion (NMP) allows for hepatocellular and biliary viability assessment prior to transplantation and might therefore enable the safe use of these orphan donor livers. We describe here the first Australasian experience of NMP-preserved liver transplants using a 'back-to-base' approach, where NMP was commenced at the recipient hospital following initial static cold storage. In the preclinical phase, 10 human donor livers declined for transplantation (7 from donation after circulatory death [DCD] and 3 from donation after brain death [DBD]) were perfused using a custom-made NMP setup. Subsequently, 10 orphan donor livers (5 from DCD and 5 from DBD) underwent NMP and viability assessment on the OrganOx metra device (OrganOx Limited, Oxford, United Kingdom). Both hepatocellular and biliary viability criteria were used. The median donor risk index was 1.53 (1.16-1.71), and the median recipient Model for End-Stage Liver Disease score was 17 (11-21). In the preclinical phase, 'back-to-base' NMP was deemed suitable and feasible. In the clinical phase, each graft met predefined criteria for implantation during NMP and was subsequently transplanted. Five (50%) recipients developed early allograft dysfunction based on peak aspartate aminotransferase. To date, all grafts function satisfactorily, and none of the 5 recipients who received a DCD liver have developed cholangiopathy. The OrganOx metra using a back-to-base approach has enabled the safe use of 10 high-risk orphan donor livers with 100% 6-month patient and graft survival. NMP improved surgeon confidence to use orphan donor livers and has enabled a safe expansion of the donor pool.

Hepatic iron concentration correlates with insulin sensitivity in nonalcoholic fatty liver disease.

Rodent and cell-culture models support a role for iron-related adipokine dysregulation and insulin resistance in the pathogenesis of nonalcoholic fatty liver disease (NAFLD); however, substantial human data are lacking. We examined the relationship between measures of iron status, adipokines, and insulin resistance in patients with NAFLD in the presence and absence of venesection. This study forms part of the Impact of Iron on Insulin Resistance and Liver Histology in Nonalcoholic Steatohepatitis (IIRON2) study, a prospective randomized controlled trial of venesection for adults with NAFLD. Paired serum samples at baseline and 6 months (end of treatment) in controls (n = 28) and patients who had venesection (n = 23) were assayed for adiponectin, leptin, resistin, retinol binding protein-4, tumor necrosis factor α, and interleukin-6, using a Quantibody, customized, multiplexed enzyme-linked immunosorbent assay array. Hepatic iron concentration (HIC) was determined using MR FerriScan. Unexpectedly, analysis revealed a significant positive correlation between baseline serum adiponectin concentration and HIC, which strengthened after correction for age, sex, and body mass index (rho = 0.36; P = 0.007). In addition, there were significant inverse correlations between HIC and measures of insulin resistance (adipose tissue insulin resistance (Adipo-IR), serum insulin, serum glucose, homeostasis model assessment of insulin resistance, hemoglobin A1c, and hepatic steatosis), whereas a positive correlation was noted with the insulin sensitivity index. Changes in serum adipokines over 6 months did not differ between the control and venesection groups. Conclusion: HIC positively correlates with serum adiponectin and insulin sensitivity in patients with NAFLD. Further study is required to establish causality and mechanistic explanations for these associations and their relevance in the pathogenesis of insulin resistance and NAFLD. (Hepatology Communications 2018;2:644-653).

Ferroportin Expression in Adipocytes Does Not Contribute to Iron Homeostasis or Metabolic Responses to a High Calorie Diet.

BACKGROUND & AIMS: Iron has an increasingly recognized role in the regulation of adipose tissue function, including the expression of adipokines involved in the pathogenesis of nonalcoholic fatty liver disease. The cellular iron exporter, ferroportin, has been proposed as being a key determinant of adipocyte iron homeostasis. METHODS: We studied an adipocyte-specific ferroportin (Fpn1) knockout mouse model, using an Adipoq-Cre recombinase driven Fpn1 deletion and fed mice according to the fast food diet model of nonalcoholic steatohepatitis. RESULTS: We showed successful selective deletion of Fpn1 in adipocytes, but found that this did not lead to increased adipocyte iron stores as measured by atomic absorption spectroscopy or histologically quantified iron granules after staining with 3,3'-diaminobenzidine-enhanced Perls' stain. Mice with adipocyte-specific Fpn1 deletion did not show dysregulation of adiponectin, leptin, resistin, or retinol-binding protein-4 expression. Similarly, adipocyte-specific Fpn1 deletion did not affect insulin sensitivity during hyperinsulinemic-euglycemic clamp studies or lead to histologic evidence of increased liver injury. We have shown, however, that the fast food diet model of nonalcoholic steatohepatitis generates an increase in adipose tissue macrophage infiltration with crown-like structures, as seen in human beings, further validating the utility of this model. CONCLUSIONS: Ferroportin may not be a key determinant of adipocyte iron homeostasis in this knockout model. Further studies are needed to determine the mechanisms of iron metabolism in adipocytes and adipose tissue.

The Implications of the Shift Toward Donation After Circulatory Death in Australia.

BACKGROUND: In recent years, an increasing number of donor livers are being declined for transplantation in Australia. The aim of this study was to evaluate the impact of donation after cardiac death and other factors associated with organ quality on liver utilization rates in Australia. METHODS: Data on organ donors who donated at least 1 organ between 2005 and 2014 were obtained from the Australia and New Zealand organ donation registry. Temporal changes in donor characteristics were assessed and a logistical regression analysis was performed to evaluate their association with liver nonuse. RESULTS: The number of organ donors increased from 175 in 2005 to 344 in 2014, with overall 19% being donation after cardiac death donors (P < 0.001). The percentage of livers deemed unsuitable for transplantation increased from 24% in 2005 to 41% in 2014 (P < 0.001). Donation after cardiac death was identified as the most important risk factor for nonuse with an odds ratio of 25.88 (95% confidence interval, 18.84-35.56), P < 0.001) followed by donor age, obesity, and diabetes. DISCUSSION: This study shows that livers donated after circulatory death are an underused resource in Australia. Better use of these currently available organs would be a highly cost-effective way of reducing waiting list mortality in liver transplantation.

Low-Dose Lipopolysaccharide Causes Biliary Injury by Blood Biliary Barrier Impairment in a Rat Hepatic Ischemia/Reperfusion Model.

This study explored whether bacterial endotoxins, in the form of lipopolysaccharides (LPS), could have an injurious effect on the biliary tract in conjunction with ischemia. A total of 64 rats were randomly assigned to 4 groups: sham operation (sham group), 1 mg/kg LPS intraperitoneal (LPS group), hepatic ischemia/reperfusion (IR; IR group), and IR combined with LPS (IR+LPS group). Following 1 or 6 hours of reperfusion, serum liver tests, bile duct histology, immunofluorescence microscopy (zonula occludens-1 [ZO-1]), bile composition (bile salts, phospholipids, lactate dehydrogenase), hepatic gene expression (bile salt transporters and inflammatory mediators), as well as serum and biliary cytokine concentrations were quantified and compared between the study groups. In addition, the integrity of the blood biliary barrier (BBB) was assayed in vivo using horseradish peroxidase (HRP). LPS administration induced severe small bile duct injury following 6 hours of reperfusion. Furthermore, total bile salts and bilirubin concentrations in serum were increased in the LPS groups compared with sham controls (LPS, + 3.3-fold and +1.9-fold; IR+LPS, + 3.8-fold and +1.7-fold, respectively). The BBB was impaired in the LPS groups as evidenced by elevated levels of HRP in bile (+4.9-fold), and decreased expression of claudin 1 (-6.7-fold) and claudin 3 (-3.6-fold). LPS was found to be a potent inducer of small bile duct injury following hepatic ischemia and 6 hours of reperfusion. This injury was associated with increased permeability of the BBB and impaired hepatic bile salt clearance. Liver Transplantation 23 194-206 2017 AASLD.

Heterozygous Hfe gene deletion leads to impaired glucose homeostasis, but not liver injury in mice fed a high-calorie diet.

Heterozygous mutations of the Hfe gene have been proposed as cofactors in the development and progression of nonalcoholic fatty liver disease (NAFLD). Homozygous Hfe deletion previously has been shown to lead to dysregulated hepatic lipid metabolism and accentuated liver injury in a dietary mouse model of NAFLD We sought to establish whether heterozygous deletion of Hfe is sufficient to promote liver injury when mice are exposed to a high-calorie diet (HCD). Eight-week-old wild-type and Hfe(+/-) mice received 8 weeks of a control diet or HCD Liver histology and pathways of lipid and iron metabolism were analyzed. Liver histology demonstrated that mice fed a HCD had increased NAFLD activity score (NAS), steatosis, and hepatocyte ballooning. However, liver injury was unaffected by Hfe genotype. Hepatic iron concentration (HIC) was increased in Hfe(+/-) mice of both dietary groups. HCD resulted in a hepcidin-independent reduction in HIC Hfe(+/-) mice demonstrated raised fasting serum glucose concentrations and HOMA-IR score, despite unaltered serum adiponectin concentrations. Downstream regulators of hepatic de novo lipogenesis (pAKT, SREBP-1, Fas, Scd1) and fatty acid oxidation (AdipoR2, Pparα, Cpt1) were largely unaffected by genotype. In summary, heterozygous Hfe gene deletion is associated with impaired iron and glucose metabolism. However, unlike homozygous Hfe deletion, heterozygous gene deletion did not affect lipid metabolism pathways or liver injury in this model.

Inconsistent hepatic antifibrotic effects with the iron chelator deferasirox.

BACKGROUND AND AIM: Development of effective antifibrotic treatments that can be translated to clinical practice is an important challenge in contemporary hepatology. A recent report on ß-thalassemia patients demonstrated that deferasirox treatment reversed or stabilized liver fibrosis independent of its iron-chelating properties. In this study, we investigated deferasirox in cell and animal models to better understand its potential antifibrotic effects. METHODS: The LX-2 stellate cell line was treated with 5 µM or 50 µM deferasirox (Exjade, Novartis Pharmaceuticals Australia, North Ryde, NSW, Australia) for up to 120 h. Three-week-old multidrug resistance 2 null (Mdr2(-/-) ) mice received oral deferasirox or vehicle for 4 weeks (30 mg/kg/day). Cells and liver tissue were collected for assessment of fibrosis and fibrogenic gene expression. RESULTS: In LX-2 cells treated with 50 µM deferasirox for 12 h, α1(I)procollagen expression was decreased by 25%, with maximal reductions (10-fold) seen following 24-120 h of treatment. Similarly, α-smooth muscle actin (αSMA) expression was significantly lower. Alterations in matrix remodeling genes, specifically decreased expression of matrix metalloproteinase-2 and tissue inhibitor of metalloproteinase-2, were observed. There was no significant difference in hepatic hydroxyproline content in Mdr2(-/-) mice following deferasirox administration (vehicle: 395 ± 27 µg/g vs deferasirox: 421 ± 33 µg/g). Similarly, no changes in the expression of fibrogenic genes were observed. CONCLUSION: Despite reductions in α1(I)procollagen and αSMA expression and alterations in matrix degradation genes in LX-2 cells, deferasirox did not exhibit antifibrotic activity in Mdr2(-/-) mice. Given the positive outcomes seen in human trials, it may be appropriate to study deferasirox in other animal models of fibrosis and/or for a longer duration of therapy.

Lack of efficacy of mTOR inhibitors and ACE pathway inhibitors as antifibrotic agents in evolving and established fibrosis in Mdr2⁻/⁻ mice.

BACKGROUND & AIMS: Mammalian target of rapamycin and angiotensin-converting enzyme inhibition has been shown to have antifibrotic activity in models of liver fibrosis. The aim of our study was to determine the efficacy of rapamycin, everolimus, irbesartan and captopril, alone and in combination, as antifibrotic agents in the Mdr2(-/-) model of cholestasis both in early injury and established disease. METHODS: Mdr2(-/-) mice were treated for 4 weeks with vehicle, rapamycin (1 mg/kg) or everolimus (5 mg/kg) every second day or with captopril (30 mg/kg/day), irbesartan (10 mg/kg/day) or vehicle. Further groups of 3-week-old Mdr2(-/-) mice were treated with rapamycin and irbesartan in combination (1 mg/kg/day and 10 mg/kg/day) or with rapamycin (2 mg/kg/day) for 4 weeks. Liver injury and fibrosis were compared between treated and untreated animals. RESULTS: There were no significant improvements in liver injury, histology, hepatic hydroxyproline or profibrogenic gene expression following treatment with rapamycin, everolimus, captopril or irbesartan at any time point studied. Likewise, there were no improvements in liver histology or profibrogenic gene expression following combination therapy or high-dose rapamycin treatment. CONCLUSIONS: The antifibrotic effects of rapamycin, everolimus, captopril and irbesartan seen in other models of fibrosis were not replicated in the Mdr2(-/-) model in this study. This highlights the clear need to test specific antifibrotic agents in a number of different animal models. We believe this animal model is ideal to study usefulness of antifibrotic agents in cholestatic liver disease because of the similarity in genetics and hepatic histopathology to human cholestatic liver disease.

A corn oil-based diet protects against combined ethanol and iron-induced liver injury in a mouse model of hemochromatosis.

BACKGROUND: Combined iron overload and alcohol may promote synergistic chronic liver injury and toxicity. The role of specific dietary fats in influencing the development of co-toxic alcoholic liver disease needs further evaluation and is investigated in this study. METHODS: Wild-type (WT) and the iron-loaded Hfe-null (Hfe(-/-) ) mice were fed chow (CC), a AIN-93G standard control (SC), or a corn oil-modified, AIN-93G-based (CO) diet with or without the addition of 20% ethanol (EtOH) in the drinking water for 8 weeks and assessed for liver injury. RESULTS: WT mice on CC, SC, and CO diets had no liver injury, although mild steatosis developed in the SC and CO groups. The addition of EtOH resulted in mild steatohepatitis in WT mice fed SC but not those on a CO diet. EtOH administration in Hfe(-/-) animals on the CC and SC diets caused marked oxidative stress, inflammatory activity, and subsinusoidal and portal-portal tract linkage fibrosis with significant up-regulation of genes involved in cellular stress signaling and fibrogenic pathways. These effects were abrogated in the CO-fed mice, despite elevated serum EtOH levels and hepatic iron concentrations, reduced hepatic glutathione and mitochondrial superoxide dismutase activities. Feeding with the CO diet led to increased hepatic glutathione peroxidase and catalase activities and attenuated alcohol-induced hepatic steatosis in the Hfe(-/-) animals. Iron and EtOH feeding markedly reduced p-STAT3 and p-AMPK protein levels, but this effect was significantly attenuated when a CO diet was consumed. CONCLUSIONS: A CO-based diet is protective against combined EtOH- and iron-induced liver toxicity, likely via attenuation of hepatic steatosis and oxidative stress and may have a role in the prevention of fibrosis development in chronic liver disease.

PEX13 deficiency in mouse brain as a model of Zellweger syndrome: abnormal cerebellum formation, reactive gliosis and oxidative stress.

Delayed cerebellar development is a hallmark of Zellweger syndrome (ZS), a severe neonatal neurodegenerative disorder. ZS is caused by mutations in PEX genes, such as PEX13, which encodes a protein required for import of proteins into the peroxisome. The molecular basis of ZS pathogenesis is not known. We have created a conditional mouse mutant with brain-restricted deficiency of PEX13 that exhibits cerebellar morphological defects. PEX13 brain mutants survive into the postnatal period, with the majority dying by 35 days, and with survival inversely related to litter size and weaning body weight. The impact on peroxisomal metabolism in the mutant brain is mixed: plasmalogen content is reduced, but very-long-chain fatty acids are normal. PEX13 brain mutants exhibit defects in reflex and motor development that correlate with impaired cerebellar fissure and cortical layer formation, granule cell migration and Purkinje cell layer development. Astrogliosis and microgliosis are prominent features of the mutant cerebellum. At the molecular level, cultured cerebellar neurons from E19 PEX13-null mice exhibit elevated levels of reactive oxygen species and mitochondrial superoxide dismutase-2 (MnSOD), and show enhanced apoptosis together with mitochondrial dysfunction. PEX13 brain mutants show increased levels of MnSOD in cerebellum. Our findings suggest that PEX13 deficiency leads to mitochondria-mediated oxidative stress, neuronal cell death and impairment of cerebellar development. Thus, PEX13-deficient mice provide a valuable animal model for investigating the molecular basis and treatment of ZS cerebellar pathology.