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\ua0weeks 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

Hepatic iron concentration correlates with insulin sensitivity in non-alcoholic 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

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

Ferroportin expression in adipocytes does not contribute to iron homeostasis or metabolic responses to a high calorie diet

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.We studied an adipocyte-specific ferroportin () knockout mouse model, using an -Cre recombinase driven deletion and fed mice according to the fast food diet model of nonalcoholic steatohepatitis.We showed successful selective deletion of in\ua0adipocytes, 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 deletion did not show dysregulation of\ua0adiponectin, leptin, resistin, or retinol-binding protein-4 expression. Similarly, adipocyte-specific 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.Ferroportin may not be a key determinant of\ua0adipocyte iron homeostasis in this knockout model. Further\ua0studies are needed to determine the mechanisms of iron metabolism in adipocytes and adipose tissue

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.</p

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

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

Association of pre-transplant statin use with delayed graft function in kidney transplant recipients

Background: Administration of HMG-CoA reductase inhibitors (statins), prior to ischemia or prior to reperfusion has been shown to decrease ischemia-reperfusion renal injury in animal studies. It is unknown whether this protective effect is applicable to renal transplantation in humans. The aim of this study was to determine the relationship between prior statin use in renal transplant recipients and the subsequent risk of delayed graft function