Ibrahim, Samar H.

Abstract With the application of modern investigative technologies, cholestatic liver diseases of genetic etiology are increasingly identified as the root cause of previously designated “idiopathic” adult and pediatric liver diseases. Here, we review advances in the field enhanced by a deeper understanding of the phenotypes associated with specific gene defects that lead to cholestatic liver diseases. There are evolving areas for clinicians in the current era specifically regarding the role for biopsy and opportunities for a “sequencing first” approach. Risk stratification based on the severity of the genetic defect holds promise to guide the decision to pursue primary liver transplantation versus medical therapy or nontransplant surgery, as well as early screening for HCC. In the present era, the expanding toolbox of recently approved therapies for hepatologists has real potential to help many of our patients with genetic causes of cholestasis. In addition, there are promising agents under study in the pipeline. Relevant to the current era, there are still gaps in knowledge of causation and pathogenesis and lack of fully accepted biomarkers of disease progression and pruritus. We discuss strategies to overcome the challenges of genotype–phenotype correlation and draw attention to the extrahepatic manifestations of these diseases. Finally, with attention to identifying causes and treatments of genetic cholestatic disorders, we anticipate a vibrant future of this dynamic field which builds upon current and future therapies, real‐world evaluations of individual and combined therapeutics, and the potential incorporation of effective gene editing and gene additive technologies.

ABSTRACTObjective:Extracorporeal membrane oxygenation (ECMO)‐associated direct hyperbilirubinemia (DHB) is likely multifactorial. The objective of this study is to assess the frequency and risk factors for developing direct hyperbilirubinemia while on ECMO, and its implication on the mortality of children.Methods:We performed a retrospective study between January 2010 and January 2020. Using Mayo Clinic electronic health record, we identified children (<18 years) who required veno‐arterial (VA) ECMO support. Demographics, ECMO indication, laboratory findings, and outcomes were abstracted. Illness acuity scores, including vasoactive‐ionotropic score (VIS), were used to assess disease severity at time of admission. Study cohort was divided into two groups: children who developed direct hyperbilirubinemia (DHB) on ECMO and children who did not (control). DHB was defined as direct bilirubin (DB) of >1.0 mg/dL. Disease acuity and mortality rates were compared between the two groups. Logistic regression was used to analyze the risk of mortality independent of potential confounding variables.Results:We identified 106 children who required ECMO support during the study period. Of those, 36 (34%) children developed DHB on ECMO. Illness acuity scores were significantly higher in the DHB group on ECMO day 2 (P = 0.046) and day 7 (P = 0.01). Mortality rate was higher in the DHB group 72%, versus 29% in the control group (P < 0.001).Conclusion:DHB was associated with a higher mortality rate than the control group.

Chanarin‐Dorfman syndrome also known as neutral lipid storage disease is a rare multisystemic autosomal recessive disorder. It is mostly encountered in patients of Mediterranean and Middle Eastern origin. Most patients are brought to medical attention secondary to dermatological manifestations namely ichthyosis. Here, we report a 10‐year‐old Kurdish male patient with ichthyosis, who was referred to pediatric liver clinic for transaminase elevation of unknown etiology despite elaborate workup. Histological findings on liver biopsy were consistent with nonalcoholic steatohepatitis. Genetic testing identified homozygous mutation C.776G>A (p.G259D) in the Abhydrolase domain containing 5 gene on chromosome 3 described in patients with Chanarin‐Dorfman syndrome. After the initiation of a diet with high medium chain triglycerides/long chain triglycerides ratio, aerobic exercise, and vitamin E, the patient liver enzymes improved. Due to debilitating ichthyosis, he was started on acitretin therapy that was discontinued due to transaminases elevation. Patient is currently stable and doing well.

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.

Liver sinusoidal endothelial cells (LSECs) are distinct subtypes of endothelial cells lining a low flow vascular bed at the interface of the liver parenchyma and the circulating immune cells and soluble factors. Emerging literature implicates LSEC in the pathogenesis and progression of nonalcoholic fatty liver disease (NAFLD). During the evolution of NAFLD, LSEC dysfunction ensues. LSECs undergo morphological and functional transformation known as “capillarization,” as well as a pathogenic increase in surface adhesion molecules expression, referred to in this review as “endotheliopathy.” LSECs govern the composition of hepatic immune cell populations in nonalcoholic steatohepatis (NASH) by mediating leukocyte subset adhesion through specific combinations of activated adhesion molecules and secreted chemokines. Moreover, extracellular vesicles released by hepatocyte under lipotoxic stress in NASH act as a catalyst for the inflammatory response and promote immune cell chemotaxis and adhesion. In the current review, we highlight leukocyte adhesion to LSEC as an initiating event in the sterile inflammatory response in NASH. We discuss preclinical studies targeting immune cells adhesion in NASH mouse models and potential therapeutic anti-inflammatory strategies for human NASH.

Nonalcoholic steatohepatitis (NASH) has become a growing public health problem worldwide, yet its pathophysiology remains unclear. Liver sinusoidal endothelial cells (LSEC) have unique morphology and function, and play a critical role in liver homeostasis. Emerging literature implicates LSEC in many pathological processes in the liver, including metabolic dysregulation, inflammation, angiogenesis, and carcinogenesis. In this review, we highlight the current knowledge of the role of LSEC in each of the progressive phases of NASH pathophysiology (steatosis, inflammation, fibrosis, and the development of hepatocellular carcinoma). We discuss processes that have important roles in NASH progression including the detrimental transformation of LSEC called “capillarization”, production of inflammatory and profibrogenic mediators by LSEC as well as LSEC-mediated angiogenesis. The current review has a special emphasis on LSEC adhesion molecules, and their key role in the inflammatory response in NASH. Moreover, we discuss the pathogenic role of extracellular vesicles and their bioactive cargos in liver intercellular communication, inflammation, and fibrosis. Finally, we highlight LSEC-adhesion molecules and derived bioactive product as potential therapeutic targets for human NASH.

AbstractNonalcoholic hepatitis (NASH) is the progressive inflammatory form of nonalcoholic fatty liver disease. Although the mechanisms of hepatic inflammation in NASH remain incompletely understood, emerging literature implicates the proinflammatory environment created by toxic lipid-induced hepatocyte injury, termed lipotoxicity. Interestingly, numerous NASH-promoting kinases in hepatocytes, immune cells, and adipocytes are activated by the lipotoxic insult associated with obesity. In the current review, we discuss recent advances in NASH-promoting kinases as disease mediators and therapeutic targets. The focus of the review is mainly on the mitogen-activated protein kinases including mixed lineage kinase 3, apoptosis signal-regulating kinase 1, c-Jun N-terminal kinase, and p38 MAPK; the endoplasmic reticulum (ER) stress kinases protein kinase RNA-like ER kinase and inositol-requiring protein-1α; as well as the Rho-associated protein kinase 1. We also discuss various pharmacological agents targeting these stress kinases in NASH that are under different phases of development.

Background and Aims Reliance on exception points to prioritize children for liver transplantation (LT) stems from concerns that the Pediatric End‐Stage Liver Disease (PELD) score underestimates mortality. Renal dysfunction and serum sodium disturbances are negative prognosticators in adult LT candidates and various pediatric populations, but are not accounted for in PELD. We retrospectively evaluated the effect of these parameters in predicting 90‐day wait‐list death/deterioration among pediatric patients (<12 years) listed for isolated LT in the United States between February 2002 and June 2018. Approach and Results Among 4,765 patients, 2,303 (49.3%) were transplanted, and 231 (4.8%) died or deteriorated beyond transplantability within 90 days of listing. Estimated glomerular filtration rate (eGFR) (hazard ratio [HR] 1.09 per 5‐unit decrease, 95% confidence interval [CI] 1.06‐1.10) and dialysis (HR 7.24, 95% CI 3.57‐14.66) were univariate predictors of 90‐day death/deterioration (P < 0.001). The long‐term benefit of LT persisted in patients with renal dysfunction, with LT as a time‐dependent covariate conferring a 2.4‐fold and 17‐fold improvement in late survival among those with mild and moderate‐to‐severe dysfunction, respectively. Adjusting for PELD, sodium was a significant nonlinear predictor of outcome, with 90‐day death/deterioration risk increased at both extremes of sodium (HR 1.20 per 1‐unit decrease below 137 mmol/L, 95% CI 1.16‐1.23; HR per 1‐unit increase above 137 mmol/L 1.13, 95% CI 1.10‐1.17, P < 0.001). A multivariable model incorporating PELD, eGFR, dialysis, and sodium demonstrated improved performance and superior calibration in predicting wait‐list outcomes relative to the PELD score. Conclusions Listing eGFR, dialysis, and serum sodium are potent, independent predictors of 90‐day death/deterioration in pediatric LT candidates, capturing risk not accounted for by PELD. Incorporation of these variables into organ allocation systems may highlight patient subsets with previously underappreciated risk, augment ability of PELD to prioritize patients for transplantation, and ultimately mitigate reliance on nonstandard exceptions.