Effect of hypoxia on aquaporins and hepatobiliary transport systems in human hepatic cells.

OBJECTIVES: Hepatic ischemia and hypoxia are accompanied by reduced bile flow, biliary sludge and cholestasis. Hepatobiliary transport systems, nuclear receptors and aquaporins were studied after hypoxia and reoxygenation in human hepatic cells. METHODS: Expression of Aquaporin 8 (AQP8), Aquaporin 9 (AQP9), Pregnane X receptor (PXR), Farnesoid X receptor (FXR), Organic anion transporting polypeptide 1 (OATP1), and the Multidrug resistance-associated protein 4 (MRP4) were investigated in induced pluripotent stem cells (iPSCs) derived hepatic cells and the immortalized hepatic line HepG2. HepG2 was subjected to combined oxygen and glucose deprivation for 4 h followed by reoxygenation. RESULTS: Expression of AQP8 and AQP9 increased during differentiation in iPSC-derived hepatic cells. Hypoxia did not alter mRNA levels of AQP8, but reoxygenation caused a marked increase in AQP8 mRNA expression. While expression of OATP1 had a transient increase during reoxygenation, MRP4 showed a delayed downregulation. Knock-down of FXR did not alter the expression of AQP8, AQP9, MRP4, or OATP1. Post-hypoxic protein levels of AQP8 were reduced after 68 h of reoxygenation compared to normoxic controls. CONCLUSIONS: Post-transcriptional mechanisms rather than reduced transcription cause reduction in AQP8 protein concentration after hypoxia-reoxygenation in hepatic cells. Expression patterns differed between hepatobiliary transport systems during hypoxia and reoxygenation. IMPACT: Expression of AQP8 and AQP9 increased during differentiation in induced pluripotent stem cells. Expression of hepatobiliary transporters varies during hypoxia and reoxygenation. Post-hypoxic protein levels of AQP8 were reduced after 68 h of reoxygenation. Post-transcriptional mechanisms rather than reduced transcription cause reduction in AQP8 protein concentration after hypoxia-reoxygenation in hepatic cells. Hypoxia and reoxygenation may affect aquaporins in hepatic cells and potentially affect bile composition.

Parenteral nutrition emulsion inhibits CYP3A4 in an iPSC derived liver organoids testing platform.

OBJECTIVES: Parenteral nutrition (PN) is used for patients of varying ages with intestinal failure to supplement calories. Premature newborns with low birth weight are at a high risk for developing PN associated liver disease (PNALD) including steatosis, cholestasis, and gallbladder sludge/stones. To optimize nutrition regimens, models are required to predict PNALD. METHODS: We have exploited induced pluripotent stem cell derived liver organoids to provide a testing platform for PNALD. Liver organoids mimic the developing liver and contain the different hepatic cell types. The organoids have an early postnatal maturity making them a suitable model for premature newborns. To mimic PN treatment we used medium supplemented with either clinoleic (80% olive oil/20% soybean oil) or intralipid (100% soybean oil) for 7 days. RESULTS: Homogenous HNF4a staining was found in all organoids and PN treatments caused accumulation of lipids in hepatocytes. Organoids exhibited a dose dependent decrease in CYP3A4 activity and expression of hepatocyte functional genes. The lipid emulsions did not affect overall organoid viability and glucose levels had no contributory effect to the observed results. CONCLUSIONS: Liver organoids could be utilized as a potential screening platform for the development of new, less hepatotoxic PN solutions. Both lipid treatments caused hepatic lipid accumulation, a significant decrease in CYP3A4 activity and a decrease in the RNA levels of both CYP3A4 and CYP1A2 in a dose dependent manner. The presence of high glucose had no additive effect, while Clinoleic at high dose, caused significant upregulation of interleukin 6 and TLR4 expression.

Aagenaes syndrome/lymphedema cholestasis syndrome 1 is caused by a founder variant in the 5'-untranslated region of UNC45A.

BACKGROUND & AIMS: Lymphedema cholestasis syndrome 1 or Aagenaes syndrome is a condition characterized by neonatal cholestasis, lymphedema, and giant cell hepatitis. The genetic background of this autosomal recessive disease was unknown up to now. METHODS: A total of 26 patients with Aagenaes syndrome and 17 parents were investigated with whole-genome sequencing and/or Sanger sequencing. PCR and western blot analyses were used to assess levels of mRNA and protein, respectively. CRISPR/Cas9 was used to generate the variant in HEK293T cells. Light microscopy, transmission electron microscopy and immunohistochemistry for biliary transport proteins were performed in liver biopsies. RESULTS: One specific variant (c.-98G>T) in the 5'-untranslated region of Unc-45 myosin chaperone A (UNC45A) was identified in all tested patients with Aagenaes syndrome. Nineteen were homozygous for the c.-98G>T variant and seven were compound heterozygous for the variant in the 5'-untranslated region and an exonic loss-of-function variant in UNC45A. Patients with Aagenaes syndrome exhibited lower expression of UNC45A mRNA and protein than controls, and this was reproduced in a CRISPR/Cas9-created cell model. Liver biopsies from the neonatal period demonstrated cholestasis, paucity of bile ducts and pronounced formation of multinucleated giant cells. Immunohistochemistry revealed mislocalization of the hepatobiliary transport proteins BSEP (bile salt export pump) and MRP2 (multidrug resistance-associated protein 2). CONCLUSIONS: c.-98G>T in the 5'-untranslated region of UNC45A is the causative genetic variant in Aagenaes syndrome. IMPACT AND IMPLICATIONS: The genetic background of Aagenaes syndrome, a disease presenting with cholestasis and lymphedema in childhood, was unknown until now. A variant in the 5'-untranslated region of the Unc-45 myosin chaperone A (UNC45A) was identified in all tested patients with Aagenaes syndrome, providing evidence of the genetic background of the disease. Identification of the genetic background provides a tool for diagnosis of patients with Aagenaes syndrome before lymphedema is evident.

Impaired Neurocognitive Performance in Children after Liver Transplantation.

OBJECTIVES: To assess longitudinal neurocognitive development after liver transplantation and evaluate factors associated with neurocognitive performance. STUDY DESIGN: Data from neurocognitive testing of 65 children (aged <18 years) who underwent liver transplantation at Oslo University Hospital between 1995 and 2018 were collected from the testing program after transplantation. The parent-reported version of the Behavior Rating Inventory of Executive Function was used to assess executive function. RESULTS: A total of 104 neurocognitive tests were conducted on 65 patients. At the first test, conducted at a median of 4.1 years (IQR, 1.5-5.3 years) after transplantation and at a median age of 6.7 years (IQR, 5.4-10.5 years), the mean full-scale IQ (FSIQ) was 91.7 ± 14, and the mean verbal comprehension index was 92.0 ± 14.5. In the 30 patients tested more than once, there was no significant difference in FSIQ between the first test at a median age of 5.8 years (IQR, 5.2-8.5 years) and the last test at a median age of 10.8 years (IQR, 9.8-12.9 years) (87.4 ± 12.9 vs 88.5 ± 13.2; P = .58). Compared with the patients who underwent transplantation a age >1 year (n = 35), those who did so at age <1 year (n = 30) had a lower FSIQ (87.1 ± 12.6 vs 96.6 ± 13.8; P = .005) and lower verbal comprehension index (87.3 ± 13.8 vs 95.4 ± 13.0; P = .020). Age at transplantation (P = .005; adjusted for cholestasis: P = .038) and transfusion of >80 mL/kg (P = .004; adjusted for age at transplantation: P = .046) were associated with FSIQ. CONCLUSIONS: Young age at transplantation and large blood transfusions during transplantation are risk factors for poor neurocognitive performance later in life. Children who undergo transplantation before 1 year of age have significantly lower neurocognitive performance compared with those who do so later in childhood. Cognitive performance did not improve over time after transplantation.

Mycophenolate mofetil use is associated with reduced incidence of food allergy in liver transplanted children.

OBJECTIVES: The incidence of food allergy in children following liver transplantation is high and the pathogenesis is still not known. We aimed to identify risk factors for development of food allergies in liver transplant children. METHODS: 107 children and adolescents who underwent liver transplantation from 1999 to 2019 were included. Data were retrospectively collected from medical records included total and specific IgE, eosinophil cationic protein and eosinophil count 12 months after transplantation and at yearly follow up (median follow-up). RESULTS: 24/107 (22%) patients reported clinical food reactions. Median time from transplantation to debut of food allergy was 1.6 (IQR 0.6-3.3) years. Mycophenolate mofetil (MMF) was discontinued in 24/78 patients (31%) due to side effects. Children treated with MMF in addition to tacrolimus one year after transplantation reported less food allergy (12.5% vs. 37.8%, p=0.003) and sensitization to food allergens one year after transplantation (8.9% vs. 17.8%, p=0.02) than those not receiving MMF. Tacrolimus trough levels did not differ between the patients treated with MMF and those who were not. Treatment with MMF two years after transplantation was associated with less food allergy (p=0.001) and food sensitization (p=0.002), also when adjusted for age at transplantation (p=0.006 and p=0.03, respectively) or for use of basilixmab (p=0.015 and p=0.018, respectively). Basiliximab was also associated with less food allergy. CONCLUSIONS: Use of MMF one and two years after transplantation was associated with less food allergy and sensitization against food allergens. The effect of MMF was not due to reduced trough levels of of tacrolimus. An infographic is available for this article at: https://links.lww.com/MPG/C821.

MicroRNA in dried blood spots from patients with Aagenaes syndrome and evaluation of pre-analytical and analytical factors.

BACKGROUND: Circulatory miRNAs are promising biomarkers. The feasibility of using miRNA from dried blood spots (DBS) was investigated using newborn screening cards from patients with cholestasis-lymphedema syndrome (Aagenaes syndrome) and controls. METHODS: Total amount of miRNA and specific miRNAs from DBS were analyzed. miRNA was also obtained from newborn screening cards in patients with cholestasis-lymphedema syndrome/Aagenaes syndrome and in healthy newborns. RESULTS: No differences in miRNA concentrations were found between multispotted samples and samples with one single drop of blood and between central and peripheral punches. Ten repeated freeze-thaw cycles did not significantly change miRNA levels from controls. miR-299 (1.73-fold change, p = 0.034) and miR-365 (1.46-fold change, p = 0.011) were upregulated and miR-30c (0.72-fold change, p = 0.0037), miR-652 (0.85-fold change, p = 0.025), and miR-744 (0.72-fold change, p = 0.0069) were downregulated in patients with Aagenaes syndrome at birth compared to controls. CONCLUSIONS: miRNAs were not affected by multispotting or punch location and were stable throughout repeated freeze-thaw cycles. miRNA in dried blood spots could be used to detect differential expression of miRNA in newborns with Aagenaes syndrome and healthy controls in newborn screening cards. Dried blood spots may be a useful source to explore circulating miRNA as biomarkers. IMPACT: Circulating miRNAs can be useful biomarkers. miRNAs from dried blood spots were not affected by multispotting or punch location and were stable throughout repeated freeze-thaw cycles. Discrimination between patients and controls are allowed even with few individuals. Early after birth, patients with cholestasis-lymphedema syndrome exhibit miRNA profiles associated with liver fibrosis. This study demonstrated that newborn screening cards may be a useful source for studying miRNA as the technical variability is smaller than biological variation.

Hepatic magnetic resonance T1-mapping and extracellular volume fraction compared to shear-wave elastography in pediatric Fontan-associated liver disease.

BACKGROUND: Children with Fontan circulation are at risk of developing hepatic fibrosis/cirrhosis. Reliable noninvasive monitoring techniques are lacking or under development. OBJECTIVE: To investigate surrogate indicators of hepatic fibrosis in adolescents with Fontan circulation by evaluating hepatic magnetic resonance (MR) T1 mapping and extracellular volume fraction measurements compared to US shear-wave elastography. MATERIALS AND METHODS: We analyzed hepatic native T1 times and extracellular volume fractions with modified Look-Locker inversion recovery. Liver stiffness was analyzed with shear-wave elastography. We compared results between 45 pediatric patients ages 16.7±0.6 years with Fontan circulation and 15 healthy controls ages 19.2±1.2 years. Measurements were correlated to clinical and hemodynamic data from cardiac catheterization. RESULTS: MR mapping was successful in 35/45 patients, revealing higher hepatic T1 times (774±44 ms) than in controls (632±52 ms; P<0.001) and higher extracellular volume fractions (47.4±5.0%) than in controls (34.6±3.8%; P<0.001). Liver stiffness was 1.91±0.13 m/s in patients vs. 1.20±0.10 m/s in controls (P<0.001). Native T1 times correlated with central venous pressures (r=0.5, P=0.007). Native T1 was not correlated with elastography in patients (r=0.2, P=0.1) or controls (r = -0.3, P=0.3). Extracellular volume fraction was correlated with elastography in patients (r=0.5, P=0.005) but not in controls (r=0.2, P=0.6). CONCLUSION: Increased hepatic MR relaxometry and shear-wave elastography values in adolescents with Fontan circulation suggested the presence of hepatic fibrosis or congestion. Central venous pressure was related to T1 times. Changes were detected differently with MR relaxometry and elastography; thus, these techniques should not be used interchangeably in monitoring hepatic fibrosis.

Cytokine profile in children with food allergy following liver transplantation.

BACKGROUND: LTX in children is associated with increased risk of food allergy, and the mechanisms underlying this are unknown. We wanted to study whether plasma cytokine profile differed in liver transplanted children, with and without food allergy, and whether it differed from untransplanted children with CLD. METHODS: Plasma cytokines, total and specific IgE in nine patients with food allergy were compared with 13 patients without food allergy following LTX, and also with seven untransplanted patients with CLD. RESULTS: No difference was found in the cytokine profile between liver transplanted patients with and without food allergy. Transplanted patients with food allergy having received a prescription of epinephrine had a significantly higher total IgE (2033 [234-2831] vs 10 [5-41] IU/L, P = .002) and MIP-1b (52 [37-96] vs 36 [32-39], P = .035) compared with transplanted patients without food allergy. Two patients with severe food allergy responded favorably to conversion from tacrolimus-based immunosuppression to MMF and corticosteroids with reduction in clinical symptoms, total IgE, specific IgE, IL-1ra, IL-4, RANTES, PDGF, MIP-1a, and TNFα. The transplantation group had higher levels of IL-1b, IL-5, IL-7, IL-13, GCSF, IFNγ, and MIP-1a compared with the CLD group. CONCLUSIONS: No overall difference was found in plasma cytokine profile between patients with and without food allergy. Patients with severe food allergy had significant elevation of MIP-1b. Discontinuation of tacrolimus reduced total and specific IgE and changed plasma cytokine profile. The plasma cytokine profile in liver transplanted children was different compared with children with CLD.

Asthma, Eczema, and Food Allergy in Children Following Liver Transplantation.

OBJECTIVES: To describe the prevalence and the relationship between asthma, eczema, food allergy, and rhinitis in children after liver transplantation. STUDY DESIGN: Children who were liver transplant recipients were investigated to assess whether the high prevalence of food allergies was accompanied by eczema, rhinitis, and asthma. Furthermore, we included 56 children with chronic liver disease to explore the risk of allergy, eczema, and asthma in this group. RESULTS: After liver transplantation, children had higher prevalence of allergic reactions to food as compared with children with chronic liver disease (P < .001). Current asthma (P = .04) and eczema (P < .02) were observed more frequently in transplanted children as compared with children with chronic liver disease. For transplanted children who had ever received tacrolimus the relative risk (RR) of asthma was 1.7 (95% CI, 1.2-2.4; P = .02) as compared with children with chronic liver disease. Transplanted children with asthma had higher rates of sensitization to food allergens than those without asthma (RR, 3.6; 95% CI, 1.3-10.3; P = .01). The most frequent food allergens associated with asthma in transplanted children were milk (RR for asthma, 3.9; 95% CI, 1.6-9.4; P < .01), eggs (RR, 2.9; 95% CI, 1.2-7.0; P = .03), and peanuts (RR, 3.7; 95% CI, 1.6-8.3; P < .01). Food allergies occurred earlier than asthma, at 1.5 years after transplantation (IQR, 0.5-3.0 years) vs 2.5 years after transplantation (IQR, 1.0-4.5 years; P < .05). Food allergies were also associated with eczema, but not with sensitization to aero-allergens or rhinitis. CONCLUSIONS: The high risk of food allergies in children who were liver transplant recipients was associated with eczema and asthma, but not rhinitis. The most frequent food allergens associated with asthma were milk, eggs, and peanuts.

Outcome for biliary atresia patients treated at a low-volume centre.

OBJECTIVES: The importance of case load for treatment of extrahepatic biliary atresia (BA) is debated. The aim of this study was to register results of BA treatment in a small volume centre. METHODS: Retrospective chart review study of patients with BA treated from 2000 to 2017. The institutional review board approved the study. RESULTS: Forty-five babies were identified of which 42 (93%) are alive. Forty-one patients had a Kasai portoenterostomy (PE), two had a hepaticojejunostomy and two had a primary liver transplantation. The age at PE/hepaticojejunostomy was median 63 (4-145 days). Seven surgeons performed the operations, and the median duration of the diagnostic work-up was 8 (3-24) days. Clearance of jaundice was achieved in 23/43 (53%) babies, and 3- and 5-year native liver survival was 47% and 40%, respectively. Clearance of jaundice post-PE/hepaticojejunostomy was a strong predictor of native liver survival (adjusted OR: 0.027; 95%; p = .009). Plasma level of conjugated bilirubin at time of referral was also a significant predictor of native liver survival (adjusted OR: 1.053; p = .017). CONCLUSION: A small volume centre may achieve satisfactory results for BA patients. The study has, however, identified factors that may further improve results; earlier referral, optimizing diagnostic work-up and establishing one dedicated surgical team.

No effect of treatment with intravenous ganciclovir on Epstein-Barr virus viremia demonstrated after pediatric liver transplantation.

EBV after pediatric LT is a risk factor for PTLD. We wanted to evaluate the effect of intravenous ganciclovir on EBV viremia and to identify risk factors for chronic EBV viremia. All pediatric patients who underwent LT in Norway from 2002 until 2015 were reviewed. Twenty-two of 38 patients with viremia were treated with intravenous ganciclovir for a median of 22 (21-38) days. Treated and untreated patients were not different with respect to EBV seroconversion prior to transplantation or age at transplantation, but treated patients had significantly earlier viremia after transplantation (P=.005). There was no difference in the proportion of patients with reduction in virus load in patients treated with ganciclovir compared to untreated patients at 8 weeks. After 1 year, five of 19 patients treated with ganciclovir and six of 14 untreated patients had reduced virus load compared to start of viremia (P=.27). In conclusion, treatment with intravenous ganciclovir did not change the proportion of patients with reduction in EBV load at 8 weeks and 1 year after viremia. Younger age at transplantation, short time from transplantation to viremia, and lack of EBV seroconversion prior to transplantation were significant predictors of chronic EBV viremia.

Impaired motor competence in children with transplanted liver.

OBJECTIVES: Although reduced cognitive function has been demonstrated after liver transplantation in children, few data are available concerning motor competence. METHODS: Thirty-five children ages 4 to 12 years were tested using Movement Assessment Battery for Children (M-ABC) test at a median of 5.1 (3.9-6.9) years after liver transplantation and compared with reference material of healthy children. RESULTS: Children with transplantation had worse M-ABC score 8.0 (interquartile range 5.0-11.5), compared with healthy children 3.5 (1.0-6.0) (P < 0.0001). All of the subscores (manual dexterity [P < 0.0001], ball skills [P = 0.0037], and balance [P = 0.0032]) were significantly worse in the children with liver transplantation compared with the healthy reference group. Twenty-nine percent of the children with liver transplantation had impaired motor competence, compared with 9% of a healthy reference group. Seventeen of the patients with transplantation were retested 1 year later, and 11 were tested 4 years later with no changes in total M-ABC score. Ball skill competence was worse 4 years after first assessment (P = 0.013). For children with transplantation and cholestatic liver disease (n =26), renal function was a significant predictor for total M-ABC score (P = 0.018). CONCLUSIONS: Children with liver transplantation had impaired motor competence compared with healthy children. Ball skills developed adversely several years after liver transplantation, and motor competence did not improve with time after transplantation. Renal function was a significant predictor for motor competence in children with liver transplantation and cholestatic liver disease.

Clinical experience with microdialysis catheters in pediatric liver transplants.

Ischemic vascular complications and rejection occur more frequently with pediatric liver transplants versus adult liver transplants. Using intrahepatic microdialysis catheters, we measured lactate, pyruvate, glucose, and glycerol values at the bedside for a median of 10 days in 20 pediatric liver grafts. Ischemia (n = 6), which was defined as a lactate level > 3.0 mM and a lactate/pyruvate ratio > 20, was detected without a measurable time delay with 100% sensitivity and 86% specificity. Rejection (n = 8), which was defined as a lactate level > 2.0 mM and a lactate/pyruvate ratio < 20 lasting for 6 or more hours, was detected with 88% sensitivity and 45% specificity. With additional clinical criteria, the specificity was 83% without a decrease in the sensitivity. Rejection was detected at a median of 4 days (range = 1-7 days) before alanine aminotransferase increased (n = 5, P = 0.11), at a median of 4 days (range = 2-9 days) before total bilirubin increased 25% or more (n = 7, P = 0.04), and at a median of 6 days (range = 4-11 days) before biopsy was performed (n = 8, P = 0.05). In conclusion, microdialysis catheters can be used to detect episodes of ischemia and rejection before current standard methods in pediatric liver transplants with clinically acceptable levels of sensitivity and specificity. The catheters were well tolerated by the children, and no major complications related to the catheters were observed.

Effect of operator experience and frequency of procedure performance on complication rate after ultrasound-guided percutaneous liver biopsies.

OBJECTIVE: The aim of the present study was to assess whether the complication rate after ultrasound-guided percutaneous liver biopsies in children is affected by how frequently the procedure is performed by the operator. METHODS: Medical charts and ultrasound descriptions of 311 ultrasound-guided percutaneous liver biopsy procedures performed by 18 radiologists at a single center from 2000 to 2011 were reviewed. Postbiopsy ultrasound the following day was performed after 97% of the procedures. RESULTS: There were no differences in the procedure-associated rate of major bleeding incidents (2.2% vs 0.8%, P = 0.38), minor bleeding incidents (15.2% vs 10.2%, P = 0.31), or abdominal pain (13.0% vs 10.6%, P = 0.61) among operators who performed ≤10 procedures and those who performed >10 procedures during the study period. A higher rate of minor bleeding incidents were recorded after liver biopsy when operators had performed <10 biopsies compared with operators who had performed >20 pediatric liver biopsies during the study period (odds ratio 3.4 [1.3-9.1], P = 0.02). No association between the number of biopsies performed by the operator during the 2 years preceding the date of the biopsy and complications was found. CONCLUSIONS: Major complications are infrequent after pediatric liver biopsies and no relation between operator experience and major complications was found. We found a significant, but minor, effect of operator procedure frequency on the rate of minor bleeding incidents after ultrasound-guided pediatric liver biopsies.

Hunting for the elusive target antigen in gestational alloimmune liver disease (GALD).

The prevailing concept is that gestational alloimmune liver disease (GALD) is caused by maternal antibodies targeting a currently unknown antigen on the liver of the fetus. This leads to deposition of complement on the fetal hepatocytes and death of the fetal hepatocytes and extensive liver injury. In many cases, the newborn dies. In subsequent pregnancies early treatment of the woman with intravenous immunoglobulin can be instituted, and the prognosis for the fetus will be excellent. Without treatment the prognosis can be severe. Crucial improvements of diagnosis require identification of the target antigen. For this identification, this work was based on two hypotheses: 1. The GALD antigen is exclusively expressed in the fetal liver during normal fetal life in all pregnancies; 2. The GALD antigen is an alloantigen expressed in the fetal liver with the woman being homozygous for the minor allele and the father being, most frequently, homozygous for the major allele. We used three different experimental approaches to identify the liver target antigen of maternal antibodies from women who had given birth to a baby with the clinical GALD diagnosis: 1. Immunoprecipitation of antigens from either a human liver cell line or human fetal livers by immunoprecipitation with maternal antibodies followed by mass spectrometry analysis of captured antigens; 2. Construction of a cDNA expression library from human fetal liver mRNA and screening about 1.3 million recombinants in Escherichia coli using antibodies from mothers of babies diagnosed with GALD; 3. Exome/genome sequencing of DNA from 26 presumably unrelated women who had previously given birth to a child with GALD with husband controls and supplementary HLA typing. In conclusion, using the three experimental approaches we did not identify the GALD target antigen and the exome/genome sequencing results did not support the hypothesis that the GALD antigen is an alloantigen, but the results do not yield basis for excluding that the antigen is exclusively expressed during fetal life., which is the hypothesis we favor.