Diminished measles immunity after paediatric liver transplantation-A retrospective, single-centre, cross-sectional analysis.

Liver transplantation in childhood has an excellent long-term outcome, but is associated with a long-term risk of infection. Measles is a vaccine-preventable infection, with case series describing severe courses with graft rejection, mechanical ventilation and even death in liver transplant recipients. Since about 30% of liver transplanted children receive liver transplants in their first year of life, not all have reached the recommended age for live vaccinations. On the contrary, live vaccines are contraindicated after transplantation. In addition, vaccination response is poorer in individuals with liver disease compared to healthy children. This retrospective, single-centre, cross-sectional study examines measles immunity in paediatric liver transplant recipients before and after transplantation. Vaccination records of 239 patients, followed up at Hannover Medical School between January 2021 and December 2022 were analysed. Twenty eight children were excluded due to stem cell transplantation, regular immunoglobulin substitution or measles vaccination after transplantation. More than 55% of all 211 children analysed and 75% of all those vaccinated at least once are measles seropositive after transplantation-48% after one and 84% after two vaccinations-which is less than in healthy individuals. Interestingly, 26% of unvaccinated children also showed measles antibodies and about 5-15% of vaccinated patients who were seronegative at the time of transplantation were seropositive afterwards, both possibly through infection. In multivariable Cox proportional hazards regression, the number of vaccinations (HR 4.30 [95% CI 2.09-8.83], p<0.001), seropositivity before transplantation (HR 2.38 [95% CI 1.07-5.30], p = 0.034) and higher age at time of first vaccination (HR 11.5 [95% CI 6.92-19.1], p<0.001) are independently associated with measles immunity after transplantation. In contrast, older age at testing is inversely associated (HR 0.09 [95% CI 0.06-0.15], p<0.001), indicating a loss of immunity. Vaccination in the first year of life does not pose a risk of non-immunity. The underlying liver disease influences the level of measles titres of twice-vaccinated patients; those with acute liver failure being the lowest compared to children with metabolic disease. In summary, vaccine response is poorer in children with liver disease. Liver transplant candidates should be vaccinated before transplantation even if this is earlier in the first year of life. Checking measles IgG and re-vaccinating seronegative patients may help to achieve immunity after transplantation.

The Impact of Thrombophilic Factors on Disease Progression in Children with Biliary Atresia-A Single-Centre Cohort Study.

Epidemiological evidence suggests that thrombophilic factors, including male sex, non-O blood type, MTHFRnt677TT mutation, factor V Leiden G1691A mutation, and prothrombin G20210A polymorphism, may contribute to the progression of fibrosis and occurrence of portal vein thrombosis in liver disease. We retrospectively investigated the effect of potentially thrombophilic factors on native liver survival as a patient-relevant endpoint of disease progression in a cohort of 142 children being followed up for biliary atresia at Hannover Medical School from April 2017 to October 2019. No significant association could be determined. There was no evidence for relevant differences in native liver survival for the Factor V Leiden G1691A mutation (hazard ratio [HR] = 0.86, 95% confidence interval [CI] 0.38-1.98, p = 0.73), prothrombin G20210A polymorphism (HR = 0.96, 95%CI 0.24-3.65, p = 0.96), non-O blood type (HR = 0.79, 95%CI 0.51-1.21, p = 0.28) or MTHFRnt677TT mutation (HR = 1.24, 95%CI 0.60-2.56, p = 0.56). A certain, albeit not strong, evidence of reduced native liver survival in male patients after Kasai hepatoportoenterostomy, particularly during the first 2000 days (42%; HR = 1.41, 95%CI 0.92-2.18, p = 0.11) was found. All children with pre-transplant portal vein thrombosis (n = 7) had non-O blood types. Larger multi-centre studies are necessary to show if the male sex or other thrombophilic factors could be potentially associated with reduced native liver survival.

Long-Term Outcome Following Liver Transplantation for Primary Hepatic Tumors-A Single Centre Observational Study over 40 Years.

The incidence of pediatric liver tumors in general has been rising over the last years and so is the number of children undergoing liver transplantation for this indication. To contribute to the ongoing improvement of pre- and post-transplant care, we aim to describe outcome and risk factors in our patient cohort. We have compared characteristics and outcome for patients transplanted for hepatoblastoma to other liver malignancies in our center between 1983 and 2022 and analysed influential factors on tumor recurrence and mortality using nominal logistic regression analysis. Of 39 children (16 f) who had transplants for liver malignancy, 31 were diagnosed with hepatoblastoma. The proportion of malignant tumors in the transplant cohort rose from 1.9% (1983-1992) to 9.1% in the current decade (p < 0.0001). Hepatoblastoma patients were transplanted at a younger age and were more likely to have tumor extent beyond the liver. Post-transplant bile flow impairment requiring intervention was significantly higher compared to our total cohort (48 vs. 24%, p > 0.0001). Hearing loss was a common side effect of ototoxic chemotherapy in hepatoblastoma patients (48%). The most common maintenance immunosuppression were mTor-inhibitors. Risk factors for tumor recurrence in patients with hepatoblastoma were higher AFP before transplant (AFPpre-LTX), a low ratio of AFPmax to AFPpre-LTX and salvage transplantation. Liver malignancies represent a rising number of indications for liver transplantation in childhood. Primary tumor resection can spare a liver transplant with all its long-term complications, but in case of tumor recurrence, transplantation might have inferior outcome. The rate of acute biopsy-proven rejections and biliary complications in comparison to our total transplant cohort needs further investigations.

Hepatitis A Immunity and Paediatric Liver Transplantation-A Single-Centre Analysis.

Following paediatric solid organ liver transplantation, risk of infection is high, both in the short and long term. Even though an infection with hepatitis A virus (HAV) is often asymptomatic and self-limited in children, some case studies describe severe cases leading to death. Vaccinations offer simple, safe and cheap protection. However, data on vaccination rates against hepatitis A in children with liver disease are scarce. Moreover, the vaccine is only approved from the age of one year old. At the same time, up to 30% of children with liver disease are transplanted within the first year of life, so the window of opportunity for vaccination is limited. This retrospective, observational, single-centre study examines the HAV immunity in paediatric liver transplant recipients before and after the first year of transplantation. Vaccination records of 229 of 279 (82.1%) children transplanted between January 2003 and June 2021 were analysed. Of 139 eligible children aged ≥ 1 year old, only 58 (41.7%) were vaccinated at least with one HAV dose prior to transplantation. In addition, seven patients received the vaccine below one year of age. After one or two doses, 38.5% or 90.6% of 65 patients were anti-HAV-IgG positive, respectively. This percentage remained stable up to the first annual check-up. For children vaccinated only once, a shorter interval from vaccination to transplantation is a risk factor for lack of immunity. Thus, HAV immunisation should be started earlier in liver transplant candidates to improve immunity in this high-risk group.

Odevixibat: an investigational inhibitor of the ileal bile acid transporter (IBAT) for the treatment of biliary atresia.

INTRODUCTION: Biliary atresia (BA) is a rare, non-curable cholestasis-causing disease in infancy, due to progressive ascending bile duct sclerosis. Even after restoration of bile flow following Kasai portoenterostomy, about half of these children need a liver transplant by their 2nd birthday, due to progressive fibrosis. Toxicity of bile acids may play a central role in disease progression, but drug therapies are not yet available. With ileal bile acid transporter (IBAT) inhibitors, there is a potential novel drug option that inhibits the absorption of bile acids in the small intestine. As a result of reduced bile acid accumulation in the cholestatic liver, it may be possible to delay hepatic remodeling. AREAS COVERED: This review summarizes the dataset on bile acids and the potential effects of odevixibat, an IBAT inhibitor, in children with BA. EXPERT OPINION: Systemic reduction of bile acids with the aim of preventing inflammation, and thus liver remodeling, is a novel, promising, therapeutic concept. In principle, however, the time until diagnosis and surgical treatment of BA should still be kept as short as possible in order to minimize liver remodeling before medical intervention can be initiated. IBAT inhibitors may add to the medical options in limiting disease progression in BA.

Ileal Bile Acid Transporter Inhibition Reduces Post-Transplant Diarrhea and Growth Failure in FIC1 Disease-A Case Report.

Familial intrahepatic cholestasis 1 (FIC1) disease is a genetic disorder characterized by hepatic and gastrointestinal disease due to ATP8B1 deficiency, often requiring liver transplantation (LT). Extrahepatic symptoms, such as diarrhea, malabsorption, and failure to thrive, do not improve and instead may be aggravated after LT. We describe a patient with FIC1 disease who underwent LT at 2 years, 8 months of age. After LT, the child developed severe refractory diarrhea and failed to thrive. The response to bile acid resins was unsatisfactory, and the parents declined our recommendation for partial external biliary diversion (PEBD). Quality of life was extremely impaired, especially due to severe diarrhea, making school attendance impossible. Attempting to reduce the total bile acids, we initiated off-label use of the ileal bile acid transporter (IBAT) inhibitor Elobixibat (Goofice™), later converted to Odevixibat (Bylvay™). After six months of treatment, the patient showed less stool output, increased weight and height, and improved physical energy levels. The child could now pursue higher undergraduate education. In our patient with FIC1 disease, the use of IBAT inhibitors was effective in treating chronic diarrhea and failure to thrive. This approach is novel; further investigations are needed to clarify the exact mode of action in this condition.

Long-Term Varicella Zoster Virus Immunity in Paediatric Liver Transplant Patients Can Be Achieved by Booster Vaccinations-A Single-Centre, Retrospective, Observational Analysis.

Varicella is one of the most common vaccine-preventable infections after paediatric solid organ transplantation; thus, vaccination offers simple and cheap protection. However, children with liver disease often progress to liver transplantation (LT) before they reach the recommended vaccination age. As a live vaccine, varicella zoster virus (VZV) vaccination after transplantation is controversial; however, many case series demonstrate that vaccination may be safe and effective in paediatric liver transplant recipients. Only limited data exists describing long-term vaccination response in such immunocompromised patients. We investigated retrospectively vaccination response in paediatric patients before and after transplantation and describe long-term immunity over ten years, including the influence of booster-vaccinations. In this retrospective, single-centre study, 458 LT recipients were analysed between September 2004 and June 2021. Of these, 53 were re-transplantations. Patients with no available vaccination records and with a history of post-transplant lymphoproliferative disease, after hematopoietic stem cell transplantation and clinical chickenpox were excluded from this analysis (n = 198). In total, data on 207 children with a median annual follow-up of 6.2 years was available: 95 patients (45.9%) were unvaccinated prior to LT. Compared to healthy children, the response to vaccination, measured by seroconversion, is weaker in children with liver disease: almost 70% after one vaccination and 93% after two vaccinations. One year after transplantation, the mean titres and the number of children with protective antibody levels (VZV IgG ≥ 50 IU/L) decreased from 77.5% to 41.3%. Neither diagnosis, gender, nor age were predictors of vaccination response. Booster-vaccination was recommended for children after seroreversion using annual titre measurements and led to a significant increase in mean titre and number of protected children. Response to vaccination shows no difference from monotherapy with a calcineurin inhibitor to intensified immunosuppression by adding prednisolone or mycophenolate mofetil. Children with liver disease show weaker seroconversion rates to VZV vaccination compared to healthy children. Therefore, VZV-naïve children should receive basic immunization with two vaccine doses as well as those vaccinated only once before transplantation. An average of 2-3 vaccine doses are required in order to achieve a long-term seroconversion and protective antibody levels in 95% of children.

Recipient-Specific Risk Factors Impairing Patient and Graft Outcome after Pediatric Liver Transplantation-Analysis of 858 Transplantations in 38 Years.

(1) Background and Aim: Despite excellent long-term results in pediatric liver transplantation (pLTx), mortality and graft loss still are to be diminished. We aim to describe time-dependent changes and long-term outcome of a large single-center pLTx cohort and to identify independent recipient-related risk factors impairing patient and graft survival. (2) Methods: This is a retrospective single-center study analyzing all pediatric liver transplants from 1983-2020. Risk factors for mortality and graft loss were identified by univariable and multi-linear regression analysis. (3) Results: We analyzed 858 liver transplantations in 705 pediatric patients. Five-year patient/graft survival increased from 60.9%/48.0% (1983-1992) to 97.5%/86.5% (OR = 12.5; p < 0.0001/OR = 6.5; p < 0.0001) (2014-2020). Indications changed significantly over time, with a higher proportion of patients being transplanted for malignancies and metabolic disease and indications of PFIC and α1AT-deficiency declining. The era of transplantation (log7.378/9.657; p < 0.0001) and indication of acute liver failure (log = 1.944/2.667; HR = 2.015/1.772; p = 0.0114/0.002) impairs patient/graft survival significantly in the multivariate analysis. Furthermore, patient survival is worsened by re-transplantation (log = 1.755; HR = 1.744; p = 0.0176) and prolonged waiting times in high-urgency status (log = 2.588; HR = 1.073; p = 0.0026), whereas the indication of biliary atresia improved outcome (log = 1.502; HR = 0.575; p = 0.0315). Graft survival was additionally impaired by pre-existing portal vein thrombosis (log = 1.482; HR = 2.016; p = 0.0330). (4) Conclusions: Despite more complex indications, patient and graft survival after pLTx continue to improve.. Acute liver failure remains the indication with poorest outcome, and listing for high urgency liver transplantation should be considered carefully and early to keep waiting time on HU list short. Furthermore, pre-transplant portal vein thrombosis should be prevented whenever possible to improve graft survival.

Under-Vaccination in Pediatric Liver Transplant Candidates with Acute and Chronic Liver Disease-A Retrospective Observational Study of the European Reference Network TransplantChild.

Infection is a serious concern in the short and long term after pediatric liver transplantation. Vaccination represents an easy and cheap opportunity to reduce morbidity and mortality due to vaccine-preventable infection. This retrospective, observational, multi-center study examines the immunization status in pediatric liver transplant candidates at the time of transplantation and compares it to a control group of children with acute liver disease. Findings show only 80% were vaccinated age-appropriately, defined as having received the recommended number of vaccination doses for their age prior to transplantation; for DTP-PV-Hib, less than 75% for Hepatitis B and two-thirds for pneumococcal conjugate vaccine in children with chronic liver disease. Vaccination coverage for live vaccines is better compared to the acute control group with 81% versus 62% for measles, mumps and rubella (p = 0.003) and 65% versus 55% for varicella (p = 0.171). Nevertheless, a country-specific comparison with national reference data suggests a lower vaccination coverage in children with chronic liver disease. Our study reveals an under-vaccination in this high-risk group prior to transplantation and underlines the need to improve vaccination.

Dubin-Johnson Syndrome as Differential Diagnosis for Neonatal Cholestasis.

OBJECTIVES: Dubin-Johnson syndrome (DJS) is an autosomal recessive disorder in which multidrug-resistance-associated protein 2 (MRP2) deficiency causes an excretion disorder of conjugated bilirubin from hepatocytes into bile canaliculi. Its clinical presentation as neonatal cholestasis (NC) is rare but represents an important differential diagnosis. We aimed to define DJS-specific characteristics in NC, in particular in contrast to biliary atresia (BA) patients, and to highlight diagnostic tools that can help to avoid invasive diagnostic tests. METHODS: We performed a review of case records from 2006 to 2020 and compared 4 DJS patients to 26 patients with proven BA consecutively diagnosed from 2014 to 2017. DJS was diagnosed by urine coproporphyrin analysis (UCA) and by genetic analysis (GA) for disease-associated ABCC2 variants. RESULTS: Four male patients with NC were diagnosed with DJS by UCA and GA. DJS patients presenting as NC showed significantly lower values for aspartate aminotransferase (AST) (P < 0.001), for alanine aminotransferase (ALT) (P = 0.002) and for gamma-glutamyl transferase (GGT) (P < 0.001) compared with BA patients. Other examinations, however, could not clearly discriminate them (e.g.: stool colour, serum bile acids, total serum bilirubin). CONCLUSIONS: DJS is not only a rare differential diagnosis in NC with a suspicious phenotype (almost normal AST, ALT) but also shows overlapping features with BA. It should, therefore, be considered in every infant with NC and an atypical liver enzyme pattern to protect patients from unnecessary, invasive examinations. For this, UCA is a fast and reliable diagnostic tool. Confirmation based on GA is recommended. DJS patients have a good long-term prognosis.

Immune Status in Children Before Liver Transplantation-A Cross-Sectional Analysis Within the ChilsSFree Multicentre Cohort Study.

Background: Both, markers of cellular immunity and serum cytokines have been proposed as potential biomarkers for graft rejection after liver transplantation. However, no good prognostic model is available for the prediction of acute cellular rejection. The impact of underlying disease and demographic factors on immune status before pediatric liver transplantation (pLTx) is still poorly understood. We investigated expression of immune markers before pLTx, in order to better understand the pre-transplant immune status. Improved knowledge of the impact of pre-transplant variables may enhance our understanding of immunological changes post pLTx in the future. Methods: This is a cross-sectional analysis of data from the ChilSFree study, a European multicentre cohort study investigating the longitudinal patterns of immune response before and after pLTx. Immune cell counts and soluble immune markers were measured in 155 children 1-30 days before pLTx by TruCount analysis and BioPlex assays. Results were logarithmised due to skewed distributions and then compared according to age, sex, and diagnosis using t-tests, ANOVAs, and Tukey post-hoc tests. The association between immune markers at time of pLTx and patients' age was assessed using a fractional polynomial approach. Multivariable regression models were used to assess the relative contribution of each factor. Results: Sex had no effect on immune status. We found strong evidence for age-specific differences in the immune status. The majority of immune markers decreased in a log-linear way with increasing age. T and B cells showed a sharp increase within the first months of life followed by a log-linear decline in older age groups. Several immune markers were strongly associated with underlying diagnoses. The effects of age and underlying disease remained virtually unchanged when adjusting for each other in multivariable models. Discussion: We show for the first time that age and diagnosis are major independent determinants of cellular and soluble immune marker levels in children with end-stage liver disease. These results need to be considered for future research on predictive immune monitoring after pLTx.

Altered NK cell function in obese healthy humans.

BACKGROUND: Obesity is associated with an elevated risk for several types of cancer and thus a major health hazard. However, the mechanism between overweight and cancer susceptibility is still elusive. Leptin, mainly produced by adipocytes links food intake and energy expenditure. In addition, recent studies have shown an immunomodulatory impact of leptin on NK cells. The purpose of the present study was to investigate whether leptin stimulation of NK cells from obese humans leads to altered functions as compared to NK cells from lean subjects. On the basis of body mass index 20 healthy individuals were classified in two groups: normal weight (<25 kg/m(2)) and obese (>30 kg/m(2)). Peripheral blood mononuclear cells (PBMC) were isolated from blood samples. We used flow cytometry to assess differences in phenotype and activity markers (CD107a, CD178 and TRAIL) of PBMCs between both groups. Furthermore, we determined after short-term in vitro leptin stimulation the phosphorylation of JAK2, downstream target of the intracellular signaling cascade of the leptin receptor, by Western Blotting and numbers of NK-cell-tumor-cell-conjugates as well as Granzyme(+) and IFN-γ(+) NK cells by flow cytometry. Finally, the proliferative capacity of control and long-term (7 days) leptin-stimulated NK cells was examined. RESULTS: As opposed to similar NK cell counts, the number of CD3(+)CD56(+) cells was significantly lower in obese compared to lean subjects. Human NK cells express the leptin receptor (Ob-R). For further determination of Ob-R, intracellular target proteins of PBMCs were investigated by Western Blotting. Phosphorylation of JAK2 was lower in obese as compared to normal weight subjects. Furthermore, significantly lower levels of TNF-related apoptosis-inducing ligand (TRAIL) as an NK cell functional marker in obese subjects were found. In vitro leptin stimulation resulted in a higher production of interferon-γ in NK cells of normal weight subjects. Interestingly, long-term leptin stimulation had no significant influence on numbers of proliferating NK cells. CONCLUSIONS: NK cells from obese healthy humans show functional deficits and altered responses after in vitro leptin challenge.

Human NK cell subset functions are differentially affected by adipokines.

BACKGROUND: Obesity is a risk factor for various types of infectious diseases and cancer. The increase in adipose tissue causes alterations in both adipogenesis and the production of adipocyte-secreted proteins (adipokines). Since natural killer (NK) cells are the host's primary defense against virus-infected and tumor cells, we investigated how adipocyte-conditioned medium (ACM) affects functions of two distinct human NK cell subsets. METHODS: Isolated human peripheral blood mononuclear cells (PBMCs) were cultured with various concentrations of human and murine ACM harvested on two different days during adipogenesis and analyzed by fluorescent-activated cell sorting (FACS). RESULTS: FACS analyses showed that the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), granzyme A (GzmA) and interferon (IFN)-γ in NK cells was regulated in a subset-specific manner. ACM treatment altered IFN-γ expression in CD56(dim) NK cells. The production of GzmA in CD56(bright) NK cells was differentially affected by the distinct adipokine compositions harvested at different states of adipogenesis. Comparison of the treatment with either human or murine ACM revealed that adipokine-induced effects on NK cell expression of the leptin receptor (Ob-R), TRAIL and IFN-γ were species-specific. CONCLUSION: Considering the growing prevalence of obesity and the various disorders related to it, the present study provides further insights into the roles human NK cell subsets play in the obesity-associated state of chronic low-grade inflammation.

Short-term and long-term leptin exposure differentially affect human natural killer cell immune functions.

Epidemiological studies have indicated that obesity is associated with a higher risk for certain cancers caused by elevated levels of adipocyte-derived hormones. Leptin, one such hormone produced by adipocytes, is a major regulator of metabolism and has also been shown to modulate immunity. However, its role in regulating human natural killer (NK) cell functions is largely unknown. Here, we show that the leptin receptor (Ob-R) is expressed on 5% of NK cells isolated from blood donors, as measured with flow cytometry, and expression of the signal-transducing long form of the leptin receptor Ob-Rb was confirmed with quantitative PCR. The Ob-R+ subpopulation displayed a lower expression of CD16, a cell surface receptor mediating antibody-dependent activation. Short-term stimulation with leptin increased IFNγ secretion, CD69 activation marker expression, and cytotoxic lysis of tumor cells; this was mediated by an improved conjugate forming between NK cells and tumor cells as well as higher expression of tumor necrosis factor-related apoptosis-inducing ligand. On the contrary, long-term incubation with leptin significantly impaired these NK cell immune functions and decreased cell proliferation. In addition, phosphorylation of Jak-2 after leptin stimulation was reduced in peripheral mononuclear blood cells from obese humans compared with normal-weight controls. NK cells represent an immune cell population that is crucial for an effective antitumor response. Here, we show that long-term exposure to leptin, similarly to the situation in obese individuals with elevated serum leptin levels, significantly impairs integral parts of NK cell immune functions, possibly linking leptin to increased cancer susceptibility in obesity.