A Learning Collaborative Approach Increases Specificity of Diagnosis of Acute Liver Failure in Pediatric Patients

Genetic aetiologies of acute liver failure

Acute liver failure (ALF) is a rare, rapidly evolving, clinical syndrome with devastating consequences where definitive treatment is by emergency liver transplantation. Establishing a diagnosis can be challenging and, historically, the cause of ALF was unidentified in up to half of children. However, recent technological and clinical advances in genomic medicine have led to an increasing proportion being diagnosed with monogenic aetiologies of ALF. The conditions encountered include a diverse group of inherited metabolic disorders each with prognostic and treatment implications. Often these disorders are clinically indistinguishable and may even mimic disorders of immune regulation or red cell disorders. Rapid genomic sequencing for children with ALF is, therefore, a key component in the diagnostic work up today. This review focuses on the monogenic aetiologies of ALF.

Identification of pediatric activated T-cell hepatitis using clinical immune studies

BACKGROUND AND AIMS

The majority of indeterminate pediatric acute liver failure (PALF) cases are secondary to immune dysregulation, labeled activated T-cell hepatitis (TCHep). We aimed to describe a cohort of children with acute severe hepatitis and PALF and define how clinical immune labs may help identify the TCHep group.

METHODS

Retrospective review of children with acute hepatitis and PALF between March 2020 and August 2022. Patients were classified as known diagnosis, indeterminate hepatitis (IND-Hep), or TCHep (defined by liver biopsy with predominant CD8 T-cell inflammation or development of aplastic anemia).

RESULTS

124 patients were identified: 83 with known diagnoses, 16 with TCHep, and 25 with IND-Hep. Patients with TCHep had significantly increased median total bilirubin levels (7.5 mg/dL (IQR 6.8-8.9) vs 1.5 mg/dL (IQR 1.0-3.6), p < 0.0001), soluble interleukin-2 receptor levels (4512 IU/mL (IQR 4073-5771) vs 2997 IU/mL (IQR 1957-3237), p = 0.02), and percent of CD8+ T-cells expressing perforin (14.5 % (IQR 8.0-20.0) vs 1.0 % (IQR 0.8-1.0), p = 0.004) and granzyme (37.5 % (IQR 15.8-54.8) vs 4.0 % (IQR 2.5-5.5), p = 0.004) compared to IND-Hep patients. Clinical flow cytometry showed that TCHep patients had significantly increased percent CD8+ T cells (29.0 % (IQR 24.5-33.5) vs 23.6 % (IQR 19.8-25.8), p = 0.04) and HLA-DR+ (16.0 % (IQR 14.5-24.5) vs 2.7 (1.8-5.3), p < 0.001) compared to IND-Hep patients indicative of increase in CD8+ T cells that are activated.

CONCLUSIONS

Peripheral blood clinical immune studies demonstrate increased markers of CD8 T-cell activation, proliferation, and cytotoxic function for TCHep patients. These readily available immune function labs can be used to help distinguish patients with TCHep from those with other causes. This provides a non-invasive tool for early detection of potential TCHep before progression to liver failure.

Clinical and Histopathologic Characteristics of Acute Severe Hepatitis Associated With Human Herpesvirus 6 Infection

Acute severe hepatitis associated with active human herpesvirus 6 (HHV-6) infection is a rare life-threatening condition with unclear clinical course and histopathology. In this study, we retrospectively analyzed 5 patients with indeterminate acute severe hepatitis found to have active hepatic HHV-6 infection during care. All patients were previously healthy children presenting with a nonspecific prodrome. Four developed acute liver failure (ALF) and 3 received liver transplantation. The explanted livers and biopsies demonstrated a centrilobular pattern of necroinflammation characterized by moderate to marked central perivenulitis and confluent centrilobular to panlobular necrosis in 4 cases, accompanied by marked hepatocellular swelling and milder portal inflammation in 3. Central perivenulitis was more prominent in comparison to a control of group of ALF without HHV-6 (P=0.01). When compared with the children with acute severe hepatitis associated with adenovirus encountered in the recent outbreak, both central perivenulitis and centrilobular necrosis were significant predictors for association with HHV-6 (P<0.01). Liver immunohistochemistry detected HHV-6 structural protein in biliary epithelium in all cases and a predominance of CD8+ T cells in the perivenular inflammatory infiltrate. Among the 4 patients with ALF, one received early anti-HHV-6 therapy and had transplant-free survival, while the other 3 received either general prophylactic antiviral treatment only (n=2) or late anti-HHV-6 therapy (n=1) and needed liver transplantation. Our findings were similar to those in previously reported cases. In summary, acute severe hepatitis associated with HHV-6 tends to affect children, progress to ALF, and exhibit characteristic centrilobular necroinflammation which likely represents an immune-mediated process.

Role of high-volume plasmapheresis in the management of paediatric acute liver failure

OBJECTIVES

Paediatric acute liver failure (PALF) is a life-threatening disease. Management aims to support hepatic regeneration or to bridge to liver transplantation. High-volume plasmapheresis (HVP) removes protein-bound substances, alleviates inflammation, and improves survival in adult acute liver failure. However, experience with HVP in PALF is limited. Aim of this study is to report on feasibility, safety, efficacy and outcomes of HVP in PALF.

METHODS

Retrospective observational study in children with PALF. HVP was performed upon identification of negative prognostic indicators, in toxic aetiology or multiorgan failure (MOF). Exchanged volume with fresh-frozen plasma corresponded to 1.5-2.0 times the patient's estimated plasma volume. One daily cycle was performed until the patient met criteria for discontinuation, that is, liver regeneration, liver transplantation, or death.

RESULTS

Twenty-two children with PALF (body weight 2.5-106 kg) received 1-7 HVP cycles. No bleeding or procedure-related mortality occurred. Alkalosis, hypothermia and reduction in platelets were observed. Haemolysis led to HVP termination in one infant. Seven children (32%) survived with their native livers, 13 patients (59%) underwent liver transplantation. Two infants died due to MOF. Overall survival was 86%. International normalization ratio (INR), alanine aminotransaminases (ALT), bilirubin and inotropic support were reduced significantly (p < 0.05) after the first HVP-cycle (median): INR 2.85 versus 1.5; ALT 1280 versus 434 U/L; bilirubin 12.7 versus 6.7 mg/dL; norepinephrine dosage 0.083 versus 0.009 µg/kg/min. Median soluble-interleukin-2-receptor dropped significantly following HVP (n = 7): 2407 versus 950 U/mL (p < 0.02).

CONCLUSIONS

HVP in PALF is feasible, safe, improves markers of liver failure and inflammation and is associated with lowering inotropic support. Prospective and controlled studies are required to confirm efficacy of HVP in PALF.

Genetic landscape of pediatric acute liver failure of indeterminate origin

BACKGROUND AND AIMS

Pediatric acute liver failure (PALF) is a life-threatening condition. In Europe, the main causes are viral infections (12%-16%) and inherited metabolic diseases (14%-28%). Yet, in up to 50% of cases the underlying etiology remains elusive, challenging clinical management, including liver transplantation. We systematically studied indeterminate PALF cases referred for genetic evaluation by whole-exome sequencing (WES), and analyzed phenotypic and biochemical markers, and the diagnostic yield of WES in this condition.

APPROACH AND RESULTS

With this international, multicenter observational study, patients (0-18 y) with indeterminate PALF were analyzed by WES. Data on the clinical and biochemical phenotype were retrieved and systematically analyzed.

RESULTS

In total, 260 indeterminate PALF patients from 19 countries were recruited between 2011 and 2022, of whom 59 had recurrent PALF. WES established a genetic diagnosis in 37% of cases (97/260). Diagnostic yield was highest in children with PALF in the first year of life (41%), and in children with recurrent acute liver failure (64%). Thirty-six distinct disease genes were identified. Defects in NBAS (n=20), MPV17 (n=8), and DGUOK (n=7) were the most frequent findings. When categorizing, the most frequent were mitochondrial diseases (45%), disorders of vesicular trafficking (28%), and cytosolic aminoacyl-tRNA synthetase deficiencies (10%). One-third of patients had a fatal outcome. Fifty-six patients received liver transplantation.

CONCLUSIONS

This study elucidates a large contribution of genetic causes in PALF of indeterminate origin with an increasing spectrum of disease entities. The high proportion of diagnosed cases and potential treatment implications argue for exome or in future rapid genome sequencing in PALF diagnostics.

Deaths Associated with Pediatric Hepatitis of Unknown Etiology, United States, October 2021-June 2023

During October 2021-June 2023, a total of 392 cases of acute hepatitis of unknown etiology in children in the United States were reported to Centers for Disease Control and Prevention as part of national surveillance. We describe demographic and clinical characteristics, including potential involvement of adenovirus in development of acute hepatitis, of 8 fatally ill children who met reporting criteria. The children had diverse courses of illness. Two children were immunocompromised when initially brought for care. Four children tested positive for adenovirus in multiple specimen types, including 2 for whom typing was completed. One adenovirus-positive child had no known underlying conditions, supporting a potential relationship between adenovirus and acute hepatitis in previously healthy children. Our findings emphasize the importance of continued investigation to determine the mechanism of liver injury and appropriate treatment. Testing for adenovirus in similar cases could elucidate the role of the virus.

Post-transplant lymphoproliferative disorder in pediatric liver transplant recipients: Experience from a South African transplant center

INTRODUCTION

Post-transplant lymphoproliferative disorder (PTLD) is a clinically heterogeneous potentially fatal complication of pediatric liver transplantation (PLT). We determined the prevalence, complications, and associated factors for PTLD in PLT recipients from Wits Donald Gordon Medical Centre, South Africa from January 2012 to August 2019.

METHODS

We performed a retrospective record review of 150 PLT recipients.

RESULTS

Histologically proven PTLD occurred in 17/150 PLT recipients (11.3%). Children with PTLD were significantly younger at transplant (17.9 vs. 32.7 months, p = 0.001) with a significantly higher prevalence of obstructive etiology (17/17 vs. 81/133, p = 0.001). Fifteen (88.2%) children with PTLD were Epstein-Barr virus (EBV) seronegative at transplant. High post-transplant EBV viral load at a threshold value of 4.8 log10 DNA copies/mL (sensitivity: 80.0% [95% confidence interval {CI}, 46.7%-100.0%]; specificity: 73.1% [95% CI 42.3%-93.3%; area under the curve {AUC} 75.8%]) and low post-transplant albumin levels at a threshold value of 21.5 g/L (sensitivity: 70.6% [95% CI, 41.2%-94.1%]; specificity: 85.7% [95% CI, 60.4%-94.5%; {AUC} 74.8%]) were associated with PTLD. The prevalence of cytomegalovirus (CMV) disease was significantly higher in children who developed PTLD versus non-PTLD (12/17 vs. 18/133; p < 0.001). CMV disease and the combination of post-transplant high EBV viral load and low albumin were independently associated with an increased risk of developing PTLD. Four (23.5%) children with PTLD died, however, survival was equivalent to non-PTLD PLT (p = 0.580).

CONCLUSION

The prevalence of PTLD in our cohort mirrors international cohorts, with mortality similar to non-PTLD PLT recipients.

[Advancements in the diagnosis and treatment of pediatric acute liver failure]

Pediatric acute liver failure (PALF) is a rare and rapidly progressive clinical syndrome with a poor prognosis and significant mortality. The etiology of PALF is complex, and it presents with diverse and atypical clinical manifestations. Accurate diagnosis based on age-related factors, early recognition or prevention of hepatic encephalopathy, and precise supportive treatment targeting the underlying cause are crucial for improving outcomes and prognosis. This article provides a comprehensive review of recent research on the diagnosis and treatment of PALF, aiming to offer guidance for clinical practice.

Improved mortality prediction for pediatric acute liver failure using dynamic prediction strategy

OBJECTIVES

To develop and validate a prediction tool for pediatric acute liver failure (PALF) mortality risks that captures the rapid and heterogeneous clinical course for accurate and updated prediction.

METHODS

Data included 1144 participants with PALF enrolled during three phases of the PALF registry study over 15 years. Using joint modeling, we built a dynamic prediction tool for mortality by combining longitudinal trajectories of multiple laboratory and clinical variables. The predictive performance for 7-day and 21-day mortality was assessed using the area under curve (AUC) through cross-validation and split-by-time validation.

RESULTS

We constructed a prognostic joint model that combines the temporal trajectories of international normalized ratio, total bilirubin, hepatic encephalopathy, platelet count, and serum creatinine. Dynamic prediction using updated information improved predictive performance over static prediction using the information at enrollment (Day 0) only. In cross-validation, AUC increased from 0.784 to 0.887 when measurements obtained between Days 1 and 2 were incorporated. AUC remained similar when we used the earlier subset of the sample for training and the later subset for testing.

CONCLUSIONS

Serial measurements of five variables in the first few days of PALF capture the dynamic clinical course of the disease and improve risk prediction for mortality. Continuous disease monitoring and updating risk prognosis are beneficial for timely and judicious medical decisions.

Disorders of vesicular trafficking presenting with recurrent acute liver failure: NBAS, RINT1, and SCYL1 deficiency

Among genetic disorders of vesicular trafficking, there are three causing recurrent acute liver failure (RALF): NBAS, RINT1, and SCYL1-associated disease. These three disorders are characterized by liver crises triggered by febrile infections and account for a relevant proportion of RALF causes. While the frequency and severity of liver crises in NBAS and RINT1-associated disease decrease with age, patients with SCYL1 variants present with a progressive, cholestatic course. In all three diseases, there is a multisystemic, partially overlapping phenotype with variable expression, including liver, skeletal, and nervous systems, all organ systems with high secretory activity. There are no specific biomarkers for these diseases, and whole exome sequencing should be performed in patients with RALF of unknown etiology. NBAS, SCYL1, and RINT1 are involved in antegrade and retrograde vesicular trafficking. Pathomechanisms remain unclarified, but there is evidence of a decrease in concentration and stability of the protein primarily affected by the respective gene defect and its interaction partners, potentially causing impairment of vesicular transport. The impairment of protein secretion by compromised antegrade transport provides a possible explanation for different organ manifestations such as bone alteration due to lack of collagens or diabetes mellitus when insulin secretion is affected. Dysfunction of retrograde transport impairs membrane recycling and autophagy. The impairment of vesicular trafficking results in increased endoplasmic reticulum stress, which, in hepatocytes, can progress to hepatocytolysis. While there is no curative therapy, an early and consequent implementation of an emergency protocol seems crucial for optimal therapeutic management.

Dynamic risk score modeling for multiple longitudinal risk factors and survival

Modeling disease risk and survival using longitudinal risk factor trajectories is of interest in various clinical scenarios. The capacity to build a prognostic model using the trajectories of multiple longitudinal risk factors, in the presence of potential dependent censoring, would enable more informed, personalized decision making. A dynamic risk score modeling framework is proposed for multiple longitudinal risk factors and survival in the presence of dependent censoring, where both events depend on participants' post-baseline clinical progression and form a competing risks structure. The model requires relatively few random effects regardless of the number of longitudinal risk factors and can therefore accommodate multiple longitudinal risk factors in a parsimonious manner. The proposed method performed satisfactorily in extensive simulation studies. It is further applied to the motivating registry study on pediatric acute liver failure to model death using the trajectories of multiple clinical and biochemical markers. Once established, the model yields an easily calculable longitudinal risk score that can be used for disease monitoring among future patients.

Paediatric acute hepatitis of unknown aetiology: a national surveillance investigation in the USA during 2021 and 2022

BACKGROUND

Adenovirus is a known cause of hepatitis in immunocompromised children, but not in immunocompetent children. In April, 2022, following multiple reports of hepatitis of unknown aetiology and adenovirus viraemia in immunocompetent children in the USA and UK, the US Centers for Disease Control and Prevention (CDC) and jurisdictional health departments initiated national surveillance of paediatric acute hepatitis of unknown aetiology. We aimed to describe the clinical and epidemiological characteristics of children identified with hepatitis of unknown aetiology between Oct 1, 2021, and Sept 30, 2022, in the USA and to compare characteristics of those who tested positive for adenovirus with those who tested negative.

METHODS

In this national surveillance investigation in the USA, children were identified for investigation if they were younger than 10 years with elevated liver transaminases (>500 U/L) who had an unknown cause for their hepatitis and onset on or after Oct 1, 2021. We reviewed medical chart abstractions, which included data on demographics, underlying health conditions, signs and symptoms of illness, laboratory results, vaccination history, radiological and liver pathology findings, diagnoses and treatment received, and outcomes. Caregiver interviews were done to obtain information on symptoms and health-care utilisation for the hepatitis illness, medical history, illness in close contacts or at school or daycare, diet, travel, and other potential exposures. Blood, stool, respiratory, and tissue specimens were evaluated according to clinician discretion and available specimens were submitted to CDC for additional laboratory testing or pathology evaluation.

FINDINGS

Surveillance identified 377 patients from 45 US jurisdictions with hepatitis of unknown aetiology with onset from Oct 1, 2021, to Sept 30, 2022. The median age of patients was 2·8 years (IQR 1·2-5·0) and 192 (51%) were male, 184 (49%) were female, and one patient had sex unknown. Only 22 (6%) patients had a notable predisposing underlying condition. 347 patients (92%) were admitted to hospital, 21 (6%) subsequently received a liver transplant, and nine (2%) died. Among the 318 patients without notable underlying conditions, 275 were tested for adenovirus. Of these 116 (42%) had at least one positive specimen, and species F type 41 was the most frequent type identified (19 [73%] of 26 typed specimens were HAdV-41). Proportions of patients who had acute liver failure, received a liver transplant, and died were similar between those who tested positive for adenovirus compared with those who tested negative. Adenovirus species F was detected by polymerase chain reaction in nine pathology liver evaluations, but not by immunohistochemistry in seven of the nine with adequate liver tissue available. Interviews with caregivers yielded no common exposures.

INTERPRETATION

Adenovirus, alone or in combination with other factors, might play a potential role in acute hepatitis among immunocompetent children identified in this investigation, but the pathophysiologic mechanism of liver injury is unclear. To inform both prevention and intervention measures, more research is warranted to determine if and how adenovirus might contribute to hepatitis risk and the potential roles of other pathogens and host factors.

FUNDING

None.

Future directions in acute liver failure

Acute liver failure (ALF) describes a clinical syndrome of rapid hepatocyte injury leading to liver failure manifested by coagulopathy and encephalopathy in the absence of pre-existing cirrhosis. The hallmark diagnostic features are a prolonged prothrombin time (ie, an international normalized ratio of prothrombin time of ≥1.5) and any degree of mental status alteration (HE). As a rare, orphan disease, it seemed an obvious target for a multicenter network. The Acute Liver Failure Study Group (ALFSG) began in 1997 to more thoroughly study and understand the causes, natural history, and management of ALF. Over the course of 22 years, 3364 adult patients were enrolled in the study registry (2614 ALF and 857 acute liver injury-international normalized ratio 2.0 but no encephalopathy-ALI) and >150,000 biosamples collected, including serum, plasma, urine, DNA, and liver tissue. Within the Registry study sites, 4 prospective substudies were conducted and published, 2 interventional ( N -acetylcysteine and ornithine phenylacetate), 1 prognostic [ 13 C-methacetin breath test (MBT)], and 1 mechanistic (rotational thromboelastometry). To review ALFSG's accomplishments and consider next steps, a 2-day in-person conference was held at UT Southwestern Medical Center, Dallas, TX, entitled "Acute Liver Failure: Science and Practice," in May 2022. To summarize the important findings in the field, this review highlights the current state of understanding of ALF and, more importantly, asks what further studies are needed to improve our understanding of the pathogenesis, natural history, and management of this unique and dramatic condition.

Rapid Genome Sequencing Diagnosis in Pediatric Patients with Liver Dysfunction

OBJECTIVE

To describe the usefulness of rapid whole genome sequencing (rWGS) in a cohort of children presenting with acute liver dysfunction.

STUDY DESIGN

This was a retrospective, population-based cohort study conducted at Primary Children's Hospital in Salt Lake City, Utah. Children meeting criteria for acute liver dysfunction who received rWGS between August 2019 and December 2021 were included. rWGS was performed on blood samples from the patient and parents (1 or both depending on availability). The clinical characteristics of patients with positive rWGS results were compared with those with negative results.

RESULTS

Eighteen patients with pediatric acute liver dysfunction who had rWGS were identified. The median turnaround time from the date rWGS testing was ordered to the date an initial report was received was 8 days with a shorter turnaround time in patients with a diagnostic rWGS (4 days vs 10 days; P = .03). A diagnostic result was identified in 7 of 18 patients (39%). Subsequently, 4 patients in this cohort, who had negative rWGS results, were found to have a toxic exposure accounting for their liver dysfunction. With removal of these patients, the diagnostic rate of rWGS was 7 of 14 (50%). The use of rWGS led to a change in management for 6 of 18 patients (33%).

CONCLUSIONS

We found that rWGS provided a diagnosis in up to 50% of pediatric acute liver dysfunction. rWGS allows for higher diagnostic rates in an expedited fashion that affects clinical management. These data support the routine use of rWGS for life-threatening disorders in children, specifically acute liver dysfunction.

Etiology and Outcome of Adult and Pediatric Acute Liver Failure in Europe

Acute liver failure (ALF) is rare but life-threatening. Common causes include intoxications, infections, and metabolic disorders. Indeterminate etiology is still frequent. No systematic data on incidence, causes, and outcome of ALF across Europe are available. Via an online survey we reached out to European Reference Network Centers on rare liver diseases. Numbers and etiology of ALF cases during 2020 were retrieved and diagnostic and treatment availabilities assessed. In total, 455 cases (306 adult, 149 pediatric) were reported from 36 centers from 20 countries. Intoxication was the most common cause in adult and pediatric care. The number of cases with indeterminate etiology is low. Diagnostic tools and specific treatment options are broadly available within this network. This is the first approach to report on etiology and outcome of ALF in the pediatric and adult population in Europe. High diagnostic yield and standard of care reflects the expert status of involved centers.

Genotypic and phenotypic spectrum of infantile liver failure due to pathogenic TRMU variants

PURPOSE

This study aimed to define the genotypic and phenotypic spectrum of reversible acute liver failure (ALF) of infancy resulting from biallelic pathogenic TRMU variants and determine the role of cysteine supplementation in its treatment.

METHODS

Individuals with biallelic (likely) pathogenic variants in TRMU were studied within an international retrospective collection of de-identified patient data.

RESULTS

In 62 individuals, including 30 previously unreported cases, we described 47 (likely) pathogenic TRMU variants, of which 17 were novel, and 1 intragenic deletion. Of these 62 individuals, 42 were alive at a median age of 6.8 (0.6-22) years after a median follow-up of 3.6 (0.1-22) years. The most frequent finding, occurring in all but 2 individuals, was liver involvement. ALF occurred only in the first year of life and was reported in 43 of 62 individuals; 11 of whom received liver transplantation. Loss-of-function TRMU variants were associated with poor survival. Supplementation with at least 1 cysteine source, typically N-acetylcysteine, improved survival significantly. Neurodevelopmental delay was observed in 11 individuals and persisted in 4 of the survivors, but we were unable to determine whether this was a primary or a secondary consequence of TRMU deficiency.

CONCLUSION

In most patients, TRMU-associated ALF was a transient, reversible disease and cysteine supplementation improved survival.

Clinical spectrum and genetic causes of mitochondrial hepatopathy phenotype in children

BACKGROUND

Alterations in both mitochondrial DNA (mtDNA) and nuclear DNA genes affect mitochondria function, causing a range of liver-based conditions termed mitochondrial hepatopathies (MH), which are subcategorized as mtDNA depletion, RNA translation, mtDNA deletion, and enzymatic disorders. We aim to enhance the understanding of pathogenesis and natural history of MH.

METHODS

We analyzed data from patients with MH phenotypes to identify genetic causes, characterize the spectrum of clinical presentation, and determine outcomes.

RESULTS

Three enrollment phenotypes, that is, acute liver failure (ALF, n = 37), chronic liver disease (Chronic, n = 40), and post-liver transplant (n = 9), were analyzed. Patients with ALF were younger [median 0.8 y (range, 0.0, 9.4) vs 3.4 y (0.2, 18.6), p < 0.001] with fewer neurodevelopmental delays (40.0% vs 81.3%, p < 0.001) versus Chronic. Comprehensive testing was performed more often in Chronic than ALF (90.0% vs 43.2%); however, etiology was identified more often in ALF (81.3% vs 61.1%) with mtDNA depletion being most common (ALF: 77% vs Chronic: 41%). Of the sequenced cohort (n = 60), 63% had an identified mitochondrial disorder. Cluster analysis identified a subset without an underlying genetic etiology, despite comprehensive testing. Liver transplant-free survival was 40% at 2 years (ALF vs Chronic, 16% vs 65%, p < 0.001). Eighteen (21%) underwent transplantation. With 33 patient-years of follow-up after the transplant, 3 deaths were reported.

CONCLUSIONS

Differences between ALF and Chronic MH phenotypes included age at diagnosis, systemic involvement, transplant-free survival, and genetic etiology, underscoring the need for ultra-rapid sequencing in the appropriate clinical setting. Cluster analysis revealed a group meeting enrollment criteria but without an identified genetic or enzymatic diagnosis, highlighting the need to identify other etiologies.

Identifying the Aetiology of Acute Liver Failure Is Crucial to Impact Positively on Outcome

Management of children with acute liver failure is challenging. In this retrospective study, paediatric patients diagnosed with ALF at our centre, in the last 26 years, were divided into two groups (G1 = diagnosed from 1997 to 2009; G2 = from 2010 to 2022) and compared to see whether they differed with regard to aetiologies, need for liver transplantation (LT), and outcome. A total of 90 children (median age 4.6 years, range 1.2-10.4; M/F = 43/47) were diagnosed with ALF, by autoimmune hepatitis (AIH) in 16 (18%), paracetamol overdose in 10 (11%), Wilson disease in 8 (9%), and other causes in 19 (21%); 37 (41%) had indeterminate ALF (ID-ALF). Comparing the two periods, the clinical features, aetiologies, and median peak values of INR [3.8 (2.9-4.8) in G1 vs. 3.2 (2.4-4.8) in G2] were similar (p > 0.05). The percentage of ID-ALF tended to be higher in G1 compared to G2 (50% vs. 32% in G2, p = 0.09). The overall percentage of patients diagnosed with Wilson disease, inborn errors of metabolism, neonatal hemochromatosis or viral infection was higher in G2 (34% vs. 13% in G1, p = 0.02). A total of 21/90 patients (23%; 5 with indeterminate ALF) were treated with steroids; 12 (14%) required extracorporeal liver support treatment. The need for LT was significantly higher in G1 compared to G2 (56% vs. 34%; p = 0.032). Among 37 children with ID-ALF, 6 (16%) developed aplastic anaemia (all in G2, p < 0.001). The survival rate at last follow up was of 94%. On a KM curve, the transplant-free survival was lower in G1 compared to G2. In conclusion, we report a lower need for LT in children diagnosed with PALF during the most recent period compared to the first era. This suggests improvements over time in the diagnosis and management of children with PALF.

Long-Term Survival Outcomes beyond the First Year after Liver Transplantation in Pediatric Acute Liver Failure Compared with Biliary Atresia: A Large-Volume Living Donor Liver Transplantation Single-Center Study

Pediatric acute liver failure (PALF) is a common cause of liver transplantation (LT) but showed poor post-LT outcomes. We reviewed 36 PALF patients and 120 BA patients who underwent LT in our institution. The cause of PALF was unknown in 66.7%. PALF patients were older (6.2 vs. 2.9 years) with higher PELD scores (31.5 vs. 24.4) and shorter waitlist time (15.7 vs. 256.1 days) (p < 0.01). PALF patients showed higher rates of post-transplant renal replacement therapy (RRT) (13.9% vs. 4.2%) and hepatic artery complications (13.9% vs. 0.8%), while portal vein complications rates were lower (0% vs. 10.8%), (p < 0.05). Although PALF patients showed lower 5-year survival rates (77.8% vs. 95.0 %, p < 0.01), the 5-year survival rates of patients who lived beyond the first year were comparable (96.6% vs. 98.3%, p = 0.516). The most common cause of deaths within one year was graft failure (75.0%) in PALF patients, but infection (67.7%) in BA patients. In multivariate analysis, lower body weight, hepatic artery complications and post-transplant RRT were associated with worse survival outcomes (p < 0.05). In conclusion, physicians should be alert to monitor the immediate postoperative graft dysfunction and hepatic artery complications and patients on post-transplant RRT in order to improve survival outcomes in PALF patients.

High Prevalence of Hemophagocytic Lymphohistiocytosis in Acute Liver Failure of Infancy

OBJECTIVES

To investigate the prevalence of hemophagocytic lymphohistiocytosis (HLH) syndrome in pediatric acute liver failure (PALF) of infancy and assess the diagnostic role of rapid immunologic tests, genotype/phenotype correlations, and clinical outcomes.

STUDY DESIGN

We retrospectively analyzed 78 children with PALF aged <24 months referred over almost 2 decades. The studied patients with a phenotype of HLH syndrome had a comprehensive immunologic workup, including additional genetic analysis for primary immunologic causes.

RESULTS

Thirty of the 78 children had the HLH phenotype and underwent genetic assessment, which demonstrated positive findings in 19 (63.3%), including 9 (30%) with biallelic primary HLH mutations and 10 (33.3%) with heterozygous mutations and/or polymorphisms. The most common form of primary HLH was familial hemophagocytic lymphohistiocytosis (FHL)-2, diagnosed in 6 children, 4 of whom had a c.50delT (p.Leu17ArgfsTer34) mutation in the PRF1 gene. Three patients with primary HLH received genetic diagnoses of FHL-3, Griscelli syndrome, and LRBA (lipopolysaccharide-responsive vesicle trafficking, beach- and anchor-containing) protein deficiency. Overall mortality in the series was 52.6% (10 of 19), and mortality in children with a documented biallelic pathogenic HLH mutation (ie, primary HLH) was 66.6% (6 of 9). Two children underwent liver transplantation, and 4 children underwent emergency hematopoietic stem cell transplantation; all but 1 child survived medium term.

CONCLUSIONS

Primary HLH can be diagnosed retrospectively in approximately one-third of infants with indeterminate PALF (iPALF) who meet the clinical criteria for HLH, often leading to their death. The most common HLH type in iPALF is FHL-2, caused by biallelic mutations in PRF-1. The clinical relevance of observed heterozygous mutations and variants of uncertain significance requires further investigation. Prompt hematopoietic stem cell transplantation could be life-saving in infants who survive the liver injury.

Development of a prognostic model for pediatric acute liver failure in a Brazilian center

OBJECTIVE

Pediatric acute liver failure (PALF) is a heterogeneous, rare, and severe condition, which outcome is survival due to liver spontaneous recovery or death. The patients who do not recover may be allocated to liver transplantation, which is the standard treatment. This study aimed to build a prognostic model to support the clinical decision to indicate liver transplantation for patients with PALF in a Brazilian center.

METHODS

The authors retrospectively analyzed the clinical variables of 120 patients in the liver transplantation program of the 'Children's Institute of the University of São Paulo, Brazil. The authors conducted a univariate analysis of variables associated with survival in PALF. Logistic multivariate analysis was performed to find a prognostic model for the outcome of patients with pediatric acute liver failure.

RESULTS

Risk factors were analyzed using univariate analysis. Two prognostic models were built using multiple logistic regression, which resulted in 2 models: model 1(INR/ALT) and model 2 (INR/Total bilirubin). Both models showed a high sensitivity (97.9%/96.9%), good positive predictive value (89.5%/90.4%), and accuracy (88.4%/88.5%), respectively. The receiver operating characteristic was calculated for both models, and the area under the curve was 0.87 for model 1 and 0.88 for model 2. The Hosmer-Lemeshow test showed that model 1 was good.

CONCLUSION

The authors built a prognostic model for PALF using INR and ALT that can contribute to the clinical decision to allocate patients to liver transplantation.

An Update on Pediatric Acute Liver Failure: Emerging Understanding of the Impact of Immune Dysregulation and Novel Opportunities for Intervention

Pediatric acute liver failure (PALF) is a complex, unpredictable, often rapidly progressive, potentially devastating clinical syndrome that occurs in infants, children, and adolescents without pre-existing liver disease. PALF is characterized by acute onset of hepatocellular injury and liver-based coagulopathy, frequently accompanied by hepatic encephalopathy. Etiologies include drug and toxin exposures, metabolic and genetic disorders, infections, and immune-mediated disease. PALF management primarily involves early contact with and consideration of transfer to a pediatric liver transplant center and intensive supportive multidisciplinary clinical care, with targeted therapies available for a subset of causes. Outcomes include survival with native liver, death, and liver transplantation. Efforts to develop reliable clinical prognostic tools to predict PALF outcomes early in the course of disease have not yet been fulfilled, and the possibility remains that some transplanted PALF patients might have survived without transplantation.

Hepatitis B and C in Children

Hepatitis B and hepatitis C are a global burden and underscore the impact of preventable acute and chronic diseases on personal as well as population level health. Caring for pediatric patients with hepatitis B and C requires a deep understanding of the pathophysiology of viral processes. Insight into the epidemiology, transmission, and surveillance of these infections is critical to prevention and therapy. Extensive research in recent years has created a growing number of treatments, changing the landscape of the medical field's approach to the viral hepatitis pandemic.

Mitochondrial Hepatopathy

Mitochondrial hepatopathies are a subset of mitochondrial diseases defined by primary dysfunction of hepatocyte mitochondria leading to a phenotype of hepatocyte cell injury, steatosis, or liver failure. Increasingly, the diagnosis is established by new sequencing approaches that combine analysis of both nuclear DNA and mitochondrial DNA and allow for timely diagnosis in most patients. Despite advances in diagnostics, for most affected children their disorders are relentlessly progressive, and result in substantial morbidity and mortality. Treatment remains mainly supportive; however, novel therapeutics and a more definitive role for liver transplantation hold promise for affected children.

Interim Analysis of Acute Hepatitis of Unknown Etiology in Children Aged <10 Years - United States, October 2021-June 2022

On April 21, 2022, CDC issued a health advisory^† encouraging U.S. clinicians to report all patients aged <10 years with hepatitis of unknown etiology to public health authorities, after identification of similar cases in both the United States (1) and Europe.^§ A high proportion of initially reported patients had adenovirus detected in whole blood specimens, thus the health advisory encouraged clinicians to consider requesting adenovirus testing, preferentially on whole blood specimens. For patients meeting the criteria in the health advisory (patients under investigation [PUIs]), jurisdictional public health authorities abstracted medical charts and interviewed patient caregivers. As of June 15, 2022, a total of 296 PUIs with hepatitis onset on or after October 1, 2021, were reported from 42 U.S. jurisdictions. The median age of PUIs was 2 years, 2 months. Most PUIs were hospitalized (89.9%); 18 (6.1%) required a liver transplant, and 11 (3.7%) died. Adenovirus was detected in a respiratory, blood, or stool specimen of 100 (44.6%) of 224 patients.^¶ Current or past infection with SARS-CoV-2 (the virus that causes COVID-19) was reported in 10 of 98 (10.2%) and 32 of 123 (26.0%) patients, respectively. No common exposures (e.g., travel, food, or toxicants) were identified. This nationwide investigation is ongoing. Further clinical data are needed to understand the cause of hepatitis in these patients and to assess the potential association with adenovirus.

Pediatric Acute Liver Failure: A Clinicopathological Perspective

Pediatric acute liver failure (PALF) is a life-threatening disorder characterized by acute hepatocellular injury occurring in children without recognized underlying liver disease. The clinicopathologic evaluation of PALF requires a different approach from that in adults. The diagnostic considerations differ depending on the age, personal and family history, geographical region, and clinical presentation. Distinct entities such as gestational alloimmune liver disease, herpes simplex virus infection, and metabolic disorders should be considered in neonates with acute liver failure, while acetaminophen toxicity and autoimmune hepatitis are more frequently seen in older children and adolescents. An identified cause for PALF despite a negative complete evaluation (indeterminate) is lacking in 30 to 50% of cases. Although not routinely performed in the setting of PALF, liver biopsy may be helpful in assessing the etiology, potential mechanisms of injury, determining the appropriateness of liver transplantation, and prognostication of the patients. In this article, we review the clinicopathologic characteristics of PALF with an emphasis on general approach of pathologic evaluation and histopathologic characteristic of selected entities.

Outcomes Analyses of Pediatric Acute Liver Failure Subjects Listed for Liver Transplantation

BACKGROUND

We characterized recent outcomes in US pediatric acute liver failure (PALF) subjects listed for liver transplantation (LT) using the Scientific Registry of Transplant Recipients (SRTR) database.

METHODS

Pediatric subjects listed for LT from 2002 to 2015 were assigned to the "PALF" group based on status 1/1A listing, INR >2, no hepatic artery thrombosis, and no primary graft nonfunction (N = 397). Subjects were assigned to the "non-PALF" group if listed with any status other than 1/1A (N = 4509).

RESULTS

The PALF group had more infants <3 months of age and males at listing for LT compared to the non-PALF group. Two-thirds of PALF subjects had an indeterminate etiology. LT waitlist survival was significantly worse in the PALF group compared to the non-PALF group. Likelihood of removal from the LT waitlist for being "too sick" was higher, while that of removal for "spontaneous recovery" was lower in PALF subjects. Post-LT short-term (30 days) and long-term (60 months) outcomes were also significantly worse in PALF versus non-PALF subjects. PALF subjects who underwent living-donor-liver-transplant (LDLT) had similar LT waitlist times and post-LT survival compared to those undergoing deceased-donor-liver-transplant (DDLT). Over the study period, we observed a decreased number of liver transplants, and increase in LT waitlist- and short-term post-LT-survival in PALF subjects.

CONCLUSION

LT waitlist and post-LT outcomes are worse in PALF subjects compared to non-PALF subjects. PALF subjects who undergo LDLT have similar waitlist times and post-LT outcomes compared to those undergoing DDLT.

Proceedings of ESPGHAN Monothematic Conference 2020: "Acute Liver Failure in Children": Diagnosis and Initial Management

OBJECTIVES

The Hepatology Committee of the European Society for Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) aims to educate pediatric gastroenterologists, members of ESPGHAN and professionals from other specialties promoting an exchange of clinical expertise in the field of pediatric hepatology. Herewith we have concentrated on detailing the recent advances in acute liver failure in infants and children.

METHODS

The 2020 ESPGHAN monothematic three-day conference on pediatric hepatology disease, entitled "acute liver failure" (ALF), was organized in Athens, Greece. ALF is a devastating disease with high mortality and most cases remain undiagnosed. As knowledge in diagnosis and treatment of ALF in infants and children has increased in the past decades, the objective was to update physicians in the field with the latest research and developments in early recognition, curative therapies and intensive care management, imaging techniques and treatment paradigms in these age groups.

RESULTS

In the first session, the definition, epidemiology, various causes of ALF, in neonates and older children and recurrent ALF (RALF) were discussed. The second session was dedicated to new aspects of ALF management including hepatic encephalopathy (HE), coagulopathy, intensive care interventions, acute on chronic liver failure, and the role of imaging in treatment and prognosis. Oral presentations by experts in various fields are summarized highlighting key learning points.

CONCLUSIONS

The current report summarizes the major learning points from this meeting. It also identifies areas where there is gap of knowledge, thereby identifying the research agenda for the near future.

North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition Position Paper on the Diagnosis and Management of Pediatric Acute Liver Failure

ABSTRACT

Pediatric acute liver failure (PALF) is a rare, rapidly progressive clinical syndrome with significant morbidity and mortality. The phenotype of PALF manifests as abrupt onset liver dysfunction, which can be brought via disparate etiology. Management is reliant upon intensive clinical care and support, often provided by the collaborative efforts of hepatologists, critical care specialists, and liver transplant surgeons. The construction of an age-based diagnostic approach, the identification of a potential underlying cause, and the prompt implementation of appropriate therapy can be lifesaving; however, the dynamic and rapidly progressive nature of PALF also demands that diagnostic inquiries be paired with monitoring strategies for the recognition and treatment of common complications of PALF. Although liver transplantation can provide a potential life-saving therapeutic option, the ability to confidently determine the certainness that liver transplant is needed for an individual child has been hampered by a lack of adequately tested clinical decision support tools and accurate predictive models. Given the accelerated progress in understanding PALF, we will provide clinical guidance to pediatric gastroenterologists and other pediatric providers caring for children with PALF by presenting the most recent advances in diagnosis, management, pathophysiology, and associated outcomes.

Study of Acute Liver Failure in Children Using Next Generation Sequencing Technology

OBJECTIVE

To use next generation sequencing (NGS) technology to identify undiagnosed, monogenic diseases in a cohort of children who suffered from acute liver failure (ALF) without an identifiable etiology.

STUDY DESIGN

We identified 148 under 10 years of age admitted to King's College Hospital, London, with ALF of indeterminate etiology between 2000 and 2018. A custom NGS panel of 64 candidate genes known to cause ALF and/or metabolic liver disease was constructed. Targeted sequencing was carried out on 41 children in whom DNA samples were available. Trio exome sequencing was performed on 4 children admitted during 2019. A comparison of the clinical characteristics of those identified with biallelic variants against those without biallelic variants was then made.

RESULTS

Homozygous and compound heterozygous variants were identified in 8 out of 41 children (20%) and 4 out of 4 children (100%) in whom targeted and exome sequencing were carried out, respectively. The genes involved were NBAS (3 children); DLD (2 children); and CPT1A, FAH, LARS1, MPV17, NPC1, POLG, SUCLG1, and TWINK (1 each). The 12 children who were identified with biallelic variants were younger at presentation and more likely to die in comparison with those who did not: median age at presentation of 3 months and 30 months and survival rate 75% and 97%, respectively.

CONCLUSIONS

NGS was successful in identifying several specific etiologies of ALF. Variants in NBAS and mitochondrial DNA maintenance genes were the most common findings. In the future, a rapid sequencing NGS workflow could help in reaching a timely diagnosis and facilitate clinical decision making in children with ALF.

Transcriptional Analysis of Liver Tissue Identifies Distinct Phenotypes of Indeterminate Pediatric Acute Liver Failure

Many patients with indeterminate pediatric acute liver failure (PALF) have evidence of T-cell driven immune injury; however, the precise inflammatory pathways are not well defined. We have characterized the hepatic cytokine and transcriptional signatures of patients with PALF. A retrospective review was performed on 22 children presenting with indeterminate (IND-PALF; n = 17) or other known diagnoses (DX-PALF; n = 6) with available archived liver tissue. Specimens were stained for clusters of differentiation 8 (CD8) T cells and scored as dense, moderate, or minimal. Measurement of immune analytes and RNA sequencing (RNA-seq) was performed on whole-liver tissue. Immune analyte data were analyzed by principal component analysis, and RNA-seq was analyzed by unsupervised hierarchical clustering, differential gene expression, and gene-set enrichment analysis. Most patients with IND-PALF (94%) had dense/moderate CD8 staining and were characterized by Th1 immune analytes including tumor necrosis factor α, interferon γ (IFN-γ), interleukin (IL) 1β, IL-12, C-X-C motif chemokine ligand (CXCL) 9, and CXCL12. Transcriptional analyses identified two transcriptional PALF phenotypes. Most patients in group 1 (91%) had IND-PALF and dense/moderate CD8 staining. This group was characterized by increased expression of genes and cell subset-specific signatures related to innate inflammation, T-cell activation, and antigen stimulation. Group 1 expressed significantly higher levels of gene signatures for regulatory T cells, macrophages, Th1 cells, T effector memory cells, cytotoxic T cells, and activated dendritic cells (adjusted P < 0.05). In contrast, patients in group 2 exhibited increased expression for genes involved in metabolic processes. Conclusion: Patients with IND-PALF have evidence of a Th1-mediated inflammatory response driven by IFN-γ. Transcriptional analyses suggest that a complex immune network may regulate an immune-driven PALF phenotype with less evidence of metabolic processes. These findings provide insight into mechanisms of hepatic injury in PALF, areas for future research, and potential therapeutic targets.

Applying an Age-specific Definition to Better Characterize Etiologies and Outcomes in Neonatal Acute Liver Failure

OBJECTIVE

Neonatal acute liver failure (ALF) is a rare disease with high mortality for which no standard age-specific definition exists. To advance the understanding of neonatal ALF, we characterize the etiology, presenting features, treatment, and outcomes in infants within 1 month of life.

METHODS

We performed a single-center 11-year retrospective chart review of neonates ≤30 days of life with ALF as defined by an INR of ≥2.0. Comparisons were made by etiology and survival with native liver (SNL). Estimated survival was performed using the Kaplan-Meier method.

RESULTS

Forty-three patients met inclusion criteria for neonatal ALF. Etiologies included viral infection (23%), gestational alloimmune liver disease with neonatal hemochromatosis (GALD-NH) (21%), cardiac-associated ischemia (16%), other ischemia (14%), genetic etiologies (9%), Trisomy 21-associated myelodysplasia (TAM) (7%), hemophagocytic lymphohistiocytosis (HLH) (2%), and not identified (7%). Infants with viral etiologies had the highest alanine aminotransferase (ALT) at presentation (1179 IU/L, interquartile range [IQR] 683-1585 IU/L) in contrast to low levels in GALD-NH (23 IU/L, IQR 18-64 IU/L). Across all etiologies, only 33% were alive at 1 year. Overall median survival was 74 days; 17 days for viral infection and 74 days for GALD-NH. Among laboratory values at presentation, alpha-fetoprotein (AFP) was significantly higher in patients that survived with their native liver (P = 0.04).

CONCLUSIONS

Overall, outcome for neonatal ALF is poor. Although initial laboratory values can differentiate viral infection or GALD-NH, further studies are needed to identify laboratory parameters that predict SNL by etiology to ultimately improve patient outcomes.

Diagnostic Approach to Acute Liver Failure in Children: A Position Paper by the SIGENP Liver Disease Working Group

Acute liver failure (ALF) is a clinical condition characterized by the abrupt onset of coagulopathy and biochemical evidence of hepatocellular injury, leading to rapid deterioration of liver cell function. In children, ALF has been characterized by raised transaminases, coagulopathy, and no known evidence of pre-existing chronic liver disease; unlike in adults, the presence of hepatic encephalopathy is not required to establish the diagnosis. Although rare, ALF has a high mortality rate without liver transplantation (LT). Etiology of ALF varies with age and geographical location, although it may remain indeterminate in a significant proportion of cases. However, identifying its etiology is crucial to undertake disease-specific management and evaluate indication to LT. In this position statement, the Liver Disease Working Group of the Italian Society of Gastroenterology, Hepatology and Nutrition (SIGENP) reviewed the most relevant studies on pediatric ALF to provide recommendations on etiology, clinical features and diagnostic work-up of neonates, infants and children presenting with ALF. Recommendations on medical management and transplant candidacy will be discussed in a following consensus conference.

Dynamics of Systemic Inflammation as a Function of Developmental Stage in Pediatric Acute Liver Failure

The Pediatric Acute Liver Failure (PALF) study is a multicenter, observational cohort study of infants and children diagnosed with this complex clinical syndrome. Outcomes in PALF reflect interactions among the child’s clinical condition, response to supportive care, disease severity, potential for recovery, and, if needed, availability of a suitable organ for liver transplantation (LTx). Previously, we used computational analyses of immune/inflammatory mediators that identified three distinct dynamic network patterns of systemic inflammation in PALF associated with spontaneous survivors, non-survivors (NS), and LTx recipients. To date, there are no data exploring age-specific immune/inflammatory responses in PALF. Accordingly, we measured a number of clinical characteristics and PALF-associated systemic inflammatory mediators in daily serum samples collected over the first 7 days following enrollment from five distinct PALF cohorts (all spontaneous survivors without LTx): infants (INF, <1 year), toddlers (TOD, 1–2 years.), young children (YCH, 2–4 years), older children (OCH, 4–13 years) and adolescents (ADO, 13–18 years). Among those groups, we observed significant (P<0.05) differences in ALT, creatinine, Eotaxin, IFN-γ, IL-1RA, IL-1β, IL-2, sIL-2Rα, IL-4, IL-6, IL-12p40, IL-12p70, IL-13, IL-15, MCP-1, MIP-1α, MIP-1β, TNF-α, and NO2−/NO3−. Dynamic Bayesian Network inference identified a common network motif with HMGB1 as a central node in all sub-groups, with MIG/CXCL9 being a central node in all groups except INF. Dynamic Network Analysis (DyNA) inferred different dynamic patterns and overall dynamic inflammatory network complexity as follows: OCH>INF>TOD>ADO>YCH. Hypothesizing that systemically elevated but sparsely connected inflammatory mediators represent pathological inflammation, we calculated the AuCon score (area under the curve derived from multiple measures over time divided by DyNA connectivity) for each mediator, and identified HMGB1, MIG, IP-10/CXCl10, sIL-2Rα, and MCP-1/CCL2 as potential correlates of PALF pathophysiology, largely in agreement with the results of Partial Least Squares Discriminant Analysis. Since NS were in the INF age group, we compared NS to INF and found greater inflammatory coordination and dynamic network connectivity in NS vs. INF. HMGB1 was the sole central node in both INF and NS, though NS had more downstream nodes. Thus, multiple machine learning approaches were used to gain both basic and potentially translational insights into a complex inflammatory disease.

Four Biomarkers Linked to Activation of Cluster of Differentiation 8-Positive Lymphocytes Predict Clinical Outcomes in Pediatric Acute Liver Failure

BACKGROUND AND AIMS

Immune dysregulation contributes to the pathogenesis of pediatric acute liver failure (PALF). Our aim was to identify immune activation markers (IAMs) in PALF that are associated with a distinct clinical phenotype and outcome.

APPROACH AND RESULTS

Among 47 PALF study participants, 12 IAMs collected ≤6 days after enrollment were measured by flow cytometry and IMMULITE assay on blood natural killer and cluster of differentiation 8-positive (CD8⁺ ) lymphocytes and subjected to unsupervised hierarchical analyses. A derivation cohort using 4 of 12 IAMs which were available in all participants (percent perforin-positive and percent granzyme-positive CD8 cells, absolute number of CD8 cells, soluble interleukin-2 receptor level) were sufficient to define high (n = 10), medium (n = 15), and low IAM (n = 22) cohorts. High IAM was more frequent among those with indeterminate etiology than those with defined diagnoses (80% versus 20%, P < 0.001). High IAM was associated with higher peak serum total bilirubin levels than low IAM (median peak 21.7 versus 4.8 mg/dL, P < 0.001) and peak coma grades. The 21-day outcomes differed between groups, with liver transplantation more frequent in high IAM participants (62.5%) than those with medium (28.2%) or low IAM (4.8%) (P = 0.002); no deaths were reported. In an independent validation cohort (n = 71) enrolled in a prior study, segregation of IAM groups by etiology, initial biochemistries, and short-term outcomes was similar, although not statistically significant. High serum aminotransferases, total bilirubin levels, and leukopenia at study entry predicted a high immune activation profile.

CONCLUSION

Four circulating T-lymphocyte activation markers identify a subgroup of PALF participants with evidence of immune activation associated with a distinct clinical phenotype and liver transplantation; these biomarkers may identify PALF participants eligible for future clinical trials of early targeted immunosuppression.

Activated CD8 T-cell Hepatitis in Children With Indeterminate Acute Liver Failure: Results From a Multicenter Cohort

OBJECTIVES

In many pediatric acute liver failure (PALF) cases, a diagnosis is not identified, and the etiology is indeterminate (IND-PALF). Our pilot study found dense CD8 T-cell infiltrates and increased T-cell clonality in liver specimens from IND-PALF patients. We aimed to validate these findings in a multicenter cohort with investigators blinded to diagnosis.

METHODS

PALF Study Group registry subjects with IND-PALF (n = 37) and known diagnoses (DX-PALF) (n = 18), ages 1 to 17 years, with archived liver tissue were included. Liver tissue slides were stained for T cells (CD8 and CD4), B cells (CD20), macrophages (CD163), perforin, and tissue resident-memory T cells (Trm, CD103), and scored as minimal, moderate, or dense. Lymphocytes were isolated from frozen liver tissue for T-cell receptor beta (TCRβ) sequencing.

RESULTS

Dense hepatic CD8 staining was found in significantly more IND-PALF (n = 29, 78%) compared with DX-PALF subjects (n = 5, 28%) (P = 0.001). IND-PALF subjects were more likely to have dense or moderate perforin (88% vs 50%, P = 0.03) and CD103 (82% vs 40%, P = 0.02) staining compared with DX-PALF subjects. TCRβ sequencing of 15 IND-PALF cases demonstrated increased clonal overlap compared with 6 DX-PALF cases (P = 0.002).

CONCLUSIONS

Dense infiltration of effector Trm CD8 T cells characterizes liver tissue from IND-PALF subjects. Increased clonality suggests the T-cell expansion is antigen(s)-driven as opposed to a nonspecific inflammatory response. These findings support CD8 staining as a new biomarker of the activated CD8 T-cell PALF phenotype. Future studies are needed to characterize potential antigens, host risk factors, and inflammatory pathways with the goal of developing targeted therapies.

Differential Diagnosis of Acute Liver Failure in Children: A Systematic Review

PURPOSE

To develop a probability-based differential diagnosis for pediatric acute liver failure (PALF) based on age and socioeconomic status of the country of origin.

METHODS

Comprehensive literature search using PubMed, EMBASE, and SCOPUS databases was performed. Children 0-22 years of age who met PALF registry criteria were included. Articles included >10 children, and could not be a case report, review article, or editorial. No language filter was utilized, but an English abstract was required. Etiology of PALF, age of child, and country of origin was extracted from included articles.

RESULTS

32 full text articles were reviewed in detail; 2,982 children were included. The top diagnosis of PALF in developed countries was acetaminophen toxicity (9.24%; 95% CredI 7.99-10.6), whereas in developing countries it was Hepatitis A (28.9%; 95% CredI 26.3-31.7). In developed countries, the leading diagnosis of PALF in children aged <1 year was metabolic disorder (17.2%; 95% CredI 10.3-25.5), whereas in developing countries it was unspecified infection (39.3%; CredI 27.6-51.8). In developed countries, the leading diagnosis in children aged >1 year was Non-A-B-C Hepatitis (8.18%; CredI 5.28-11.7), whereas in developing countries it was Hepatitis A (32.4%; CredI 28.6-36.3).

CONCLUSION

The leading causes of PALF in children aged 0-22 years differ depending on the age and developmental status of their country of origin, suggesting that these factors must be considered in the evaluation of children with PALF.

Hepatitis C in 2020: A North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition Position Paper

In 1989, a collaboration between the Centers for Disease Control (CDC) and a California biotechnology company identified the hepatitis C virus (HCV, formerly known as non-A, non-B hepatitis virus) as the causative agent in the epidemic of silent posttransfusion hepatitis resulting in cirrhosis. We now know that, the HCV genome is a 9.6 kb positive, single-stranded RNA. A single open reading frame encodes a 3011 amino acid residue polyprotein that undergoes proteolysis to yield 10 individual gene products, consisting of 3 structural proteins (core and envelope glycoproteins E1 and E2) and 7 nonstructural (NS) proteins (p7, NS2, NS3, NS4A, NS4B, NS5A, and NS5B), which participate in posttranslational proteolytic processing and replication of HCV genetic material. Less than 25 years later, a new class of medications, known as direct-acting antivirals (DAAs) which target these proteins, were introduced to treat HCV infection. These highly effective antiviral agents are now approved for use in children as young as 3 years of age and have demonstrated sustained virologic responses exceeding 90% in most genotypes. Although tremendous scientific progress has been made, the incidence of acute HCV infections has increased by 4-fold since 2005, compounded in the last decade by a surge in opioid and intravenous drug use. Unfortunately, awareness of this deadly hepatotropic virus among members of the lay public remains limited. Patient education, advocacy, and counseling must, therefore, complement the availability of curative treatments against HCV infection if this virus is to be eradicated.

Indian National Association for the Study of Liver Consensus Statement on Acute Liver Failure (Part-2): Management of Acute Liver Failure

Acute liver failure (ALF) is not an uncommon complication of a common disease such as acute hepatitis. Viral hepatitis followed by antituberculosis drug-induced hepatotoxicity are the commonest causes of ALF in India. Clinically, such patients present with appearance of jaundice, encephalopathy, and coagulopathy. Hepatic encephalopathy (HE) and cerebral edema are central and most important clinical event in the course of ALF, followed by superadded infections, and determine the outcome in these patients. The pathogenesis of encephalopathy and cerebral edema in ALF is unique and multifactorial. Ammonia plays a crucial role in the pathogenesis, and several therapies aim to correct this abnormality. The role of newer ammonia-lowering agents is still evolving. These patients are best managed at a tertiary care hospital with facility for liver transplantation (LT). Aggressive intensive medical management has been documented to salvage a substantial proportion of patients. In those with poor prognostic factors, LT is the only effective therapy that has been shown to improve survival. However, recognizing suitable patients with poor prognosis has remained a challenge. Close monitoring, early identification and treatment of complications, and couseling for transplant form the first-line approach to manage such patients. Recent research shows that use of dynamic prognostic models is better for selecting patients undergoing liver transplantation and timely transplant can save life of patients with ALF with poor prognostic factors.

Acute hepatitis and acute liver failure: Pathologic diagnosis and differential diagnosis

Acute hepatitis and acute liver failure are severe medical conditions that require early clinical intervention. Histopathologic findings on a liver biopsy or a liver explant may help identify the underlying etiology or provide an important direction for further clinical, laboratory and radiographical investigation. This review is divided into two main portions. The first portion concentrates on various etiologies and discusses unique histologic features that can be associated with specific etiologies. The second portion describes the general morphologic features based on which the diagnosis of acute hepatitis and acute liver failure are made. Histopathologic distinction between collapse and cirrhosis and limitations of histopathologic assessment for underlying etiologies are addressed in this portion. Another focus of this review is non-necrotic acute liver failure, which typically features diffuse microvesicular steatosis secondary to various etiologies causing mitochondrial dysfunction. Molecular testing serves an increasingly important role in the diagnosis and management of this group of disorders.

Corticosteroid Therapy for Indeterminate Pediatric Acute Liver Failure and Aplastic Anemia with Acute Hepatitis

OBJECTIVE

To examine the characteristics and outcomes of a multicenter patient cohort with indeterminate pediatric acute liver failure (IND-PALF) and with aplastic anemia with acute hepatitis treated with corticosteroids.

STUDY DESIGN

Retrospective study of patients age 1-17 years with IND-PALF and aplastic anemia with acute hepatitis who presented between 2009 and 2018 to 1 of 4 institutions and were treated with corticosteroids for presumed immune dysregulation.

RESULTS

Of 28 patients with IND-PALF (median of 4.0 years of age [range 1-16] and 71% male) 71% (n = 20) were treated with 0.5-4 mg/kg/day of intravenous methylprednisolone, and 8 patients received 10 mg/kg/day followed by a taper. By 21 days postcorticosteroid initiation, 14 patients (50%) underwent liver transplantation, 13 patients (46%) recovered with their native liver, and 1 patient (4%) died. Patients who recovered with their native liver received a median of 139 days (range 19-749) of corticosteroid therapy, with a median of 12 days (range 1-240) to international normalized ratio ≤1.2. Patients with aplastic anemia with acute hepatitis (n = 6; median of 9.5 years of age [range 1-12], 83% male), received 1-2 mg/kg/day of methylprednisolone for a median of 100 days (range 63-183), and all recovered with their native liver. One patient with IND-PALF and 2 patients with aplastic anemia with acute hepatitis developed a serious infection within 90 days postcorticosteroid initiation.

CONCLUSIONS

Many patients with IND-PALF or aplastic anemia with acute hepatitis that were treated with corticosteroids improved, but survival with native liver may not be different from historical reports. A randomized controlled trial exploring the benefits and risks of steroid therapy is needed before it is adopted broadly.