Juvenile polyposis syndrome in children: The impact of SMAD4 and BMPR1A mutations on clinical phenotype and polyp burden.

OBJECTIVE: A constitutional disease-causing variant (DCV) in the SMAD4 or BMPR1A genes is present in 40%-60% of patients with juvenile polyposis syndrome (JPS). The aim of this study was to characterize the clinical course and polyp burden in children with DCV-positive JPS compared to DCV-negative JPS. METHODS: Demographic, clinical, genetic, and endoscopic data of children with JPS were compiled from eight international centers in the ESPHGAN/NASPGHAN polyposis working group. RESULTS: A total of 124 children with JPS were included: 69 (56%) DCV-negative and 55 (44%) DCV-positive (53% SMAD4 and 47% BMPR1A) with a median (interquartile range [IQR]) follow-up of 4 (2.8-6.4) years. DCV-positive children were diagnosed at an older age compared to DCV-negative children [12 (8-15.7) years vs. 5 (4-7) years, respectively, p < 0.001], had a higher frequency of family history of polyposis syndromes (50.9% vs. 1.4%, p < 0.001), experienced a greater frequency of extraintestinal manifestations (27.3% vs. 5.8%, p < 0.001), and underwent more gastrointestinal surgeries (16.4% vs. 1.4%, p = 0.002). The incidence rate ratio for the development of new colonic polyps was 6.15 (95% confidence interval 3.93-9.63, p < 0.001) in the DCV-positive group compared to the DCV-negative group, with an average of 12.2 versus 2 new polyps for every year of follow-up. There was no difference in the burden of polyps between patients with SMAD4 and BMPR1A mutations. CONCLUSIONS: This largest international cohort of pediatric JPS revealed that DCV-positive and DCV-negative children exhibit distinct clinical phenotype. These findings suggest a potential need of differentiated surveillance strategies based upon mutation status.

Regulation of PGC1α Downstream of the Insulin Signaling Pathway Plays a Role in the Hepatic Proteotoxicity of Mutant α1-Antitrypsin Deficiency Variant Z.

BACKGROUND & AIMS: Insulin signaling is known to regulate essential proteostasis mechanisms. METHODS: The analyses here examined effects of insulin signaling in the PiZ mouse model of α1-antitrypsin deficiency in which hepatocellular accumulation and proteotoxicity of the misfolded α1-antitrypsin Z variant (ATZ) causes liver fibrosis and cancer. RESULTS: We first studied the effects of breeding PiZ mice to liver-insulin-receptor knockout (LIRKO) mice (with hepatocyte-specific insulin-receptor gene disruption). The results showed decreased hepatic ATZ accumulation and liver fibrosis in PiZ x LIRKO vs PiZ mice, with reversal of those effects when we bred PiZ x LIRKO mice onto a FOXO1-deficient background. Increased intracellular degradation of ATZ mediated by autophagy was identified as the likely mechanism for diminished hepatic proteotoxicity in PiZ x LIRKO mice and the converse was responsible for enhanced toxicity in PiZ x LIRKO x FOXO1-KO animals. Transcriptomic studies showed major effects on oxidative phosphorylation and autophagy genes, and significant induction of peroxisome proliferator-activated-receptor-γ-coactivator-1α (PGC1α) expression in PiZ-LIRKO mice. Because PGC1α plays a key role in oxidative phosphorylation, we further investigated its effects on ATZ proteostasis in our ATZ-expressing mammalian cell model. The results showed PGC1α overexpression or activation enhances autophagic ATZ degradation. CONCLUSIONS: These data implicate suppression of autophagic ATZ degradation by down-regulation of PGC1α as one mechanism by which insulin signaling exacerbates hepatic proteotoxicity in PiZ mice, and identify PGC1α as a novel target for development of new human α1-antitrypsin deficiency liver disease therapies.

Modeling net ecosystem carbon balance and loss in coastal wetlands exposed to sea-level rise and saltwater intrusion.

Coastal wetlands are globally important stores of carbon (C). However, accelerated sea-level rise (SLR), increased saltwater intrusion, and modified freshwater discharge can contribute to the collapse of peat marshes, converting coastal peatlands into open water. Applying results from multiple experiments from sawgrass (Cladium jamaicense)-dominated freshwater and brackish water marshes in the Florida Coastal Everglades, we developed a system-level mechanistic peat elevation model (EvPEM). We applied the model to simulate net ecosystem C balance (NECB) and peat elevation in response to elevated salinity under inundation and drought exposure. Using a mass C balance approach, we estimated net gain in C and corresponding export of aquatic fluxes ( F AQ $$ {F}_{\mathrm{AQ}} $$ ) in the freshwater marsh under ambient conditions (NECB = 1119 ± 229 gC m-2  year-1 ; FAQ  = 317 ± 186 gC m-2  year-1 ). In contrast, the brackish water marsh exhibited substantial peat loss and aquatic C export with ambient (NECB = -366 ± 15 gC m-2  year-1 ; FAQ  = 311 ± 30 gC m-2  year-1 ) and elevated salinity (NECB = -594 ± 94 gC m-2  year-1 ; FAQ  = 729 ± 142 gC m-2  year-1 ) under extended exposed conditions. Further, mass balance suggests a considerable decline in soil C and corresponding elevation loss with elevated salinity and seasonal dry-down. Applying EvPEM, we developed critical marsh net primary productivity (NPP) thresholds as a function of salinity to simulate accumulating, steady-state, and collapsing peat elevations. The optimization showed that ~150-1070 gC m-2  year-1 NPP could support a stable peat elevation (elevation change ≈ SLR), with the corresponding salinity ranging from 1 to 20 ppt under increasing inundation levels. The C budgeting and modeling illustrate the impacts of saltwater intrusion, inundation, and seasonal dry-down and reduce uncertainties in understanding the fate of coastal peat wetlands with SLR and freshwater restoration. The modeling results provide management targets for hydrologic restoration based on the ecological conditions needed to reduce the vulnerability of the Everglades' peat marshes to collapse. The approach can be extended to other coastal peatlands to quantify C loss and improve understanding of the influence of the biological controls on wetland C storage changes for coastal management.

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.

Invasive Ductular Reaction: Form and Function.

This commentary highlights the article by Clerbaux et al that describes the critical role of invasive ductular reaction in hepatocellular injury.

The Year in Electrophysiology: Selected Highlights from 2019.

This article is the second in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia. The authors thank the Editor-in-Chief, Dr. Kaplan, the Associate Editor-in-Chief, Dr. Augoustides, and the editorial board for the opportunity to continue this series, namely the highlights of the year that pertain to electrophysiology in relation to cardiothoracic and vascular anesthesia. This second article focuses on cardiac sympathetic denervation, the management of patients with atrial fibrillation, cerebral oximetry for catheter ablation procedures, advancements in leadless pacemaker and subcutaneous implantable cardioverter defibrillator technology, and the emergence of pulsed field ablation for pulmonary vein isolation.

Liver Transplant Listing in Pediatric Acute Liver Failure: Practices and Participant Characteristics.

Liver transplant (LT) decisions in pediatric acute liver failure (PALF) are complex. Three phases of the PALF registry, containing data on 1,144 participants over 15 years, were interrogated to characterize clinical features associated with listing status. A decrease in the cumulative incidence of listing (P < 0.005) and receiving (P < 0.05) LT occurred without an increase in the cumulative incidence of death (P = 0.67). Time to listing was constant and early (1 day; quartiles 1-3 = 0-2; P = 0.88). The most frequent reasons for not listing were "not sick enough" and "medically unsuitable." Participants listed for LT were more likely male, with coma grade scores >0; had higher international normalized ratio, bilirubin, lactate, and venous ammonia; and had lower peripheral lymphocytes and transaminase levels compared to those deemed "not sick enough." Participants listed versus those deemed "medically unsuitable" were older; had higher serum aminotransferase levels, bilirubin, platelets, and albumin; and had lower lactate, venous ammonia, and lymphocyte count. An indeterminate diagnosis was more prevalent in listed participants. Ventilator (23.8%) and vasopressor (9.2%) support occurred in a significant portion of listed participants but less frequently than in those who were not "medically suitable." Removal from the LT list was a rare event. Conclusion: The cumulative incidence of listing for and receiving LT decreased throughout the PALF study without an increase in the cumulative incidence of death. While all participants fulfilled entry criteria for PALF, significant differences were noted between participants listed for LT and those deemed "not sick enough" as well as those who were "medically unsuitable." Having an indeterminate diagnosis and a requirement for cardiopulmonary support appeared to influence decisions toward listing; optimizing listing decisions in PALF may reduce the frequency of LT without increasing the frequency of death.

Transcription factor GATA6: a novel marker and putative inducer of ductal metaplasia in biliary atresia.

Biliary atresia (BA), a neonatal liver disease, is characterized by obstruction of extrahepatic bile ducts with subsequent cholestasis, inflammation, and progressive liver fibrosis. To gain insights into the pathophysiology of BA, we focused attention on GATA6, a transcription factor implicated in biliary development. Early in fetal development GATA6 expression is evident in cholangiocytes and hepatocytes, but by late gestation it is extinguished in hepatocytes. Utilizing a unique set of BA liver samples collected before and after successful portoenterostomy (PE), we found that GATA6 expression is markedly upregulated in hepatocytes of patients with BA compared with healthy and cholestatic disease controls. This upregulation is recapitulated in two murine models simulating bile duct obstruction and intrahepatic bile ductule expansion. GATA6 expression in BA livers correlates with two established negative prognostic indicators (age at PE, degree of intrahepatic bile ductule expansion) and decreases after normalization of serum bilirubin by PE. GATA6 expression in BA livers correlates with expression of known regulators of cholangiocyte differentiation ( JAGGED1, HNF1ß, and HNF6). These same genes are upregulated after enforced expression of GATA6 in human hepatocyte cell models. In conclusion, GATA6 is a novel marker and a putative driver of hepatocyte-cholangiocyte metaplasia in BA, and its expression in hepatocytes is downregulated after successful PE. NEW & NOTEWORTHY A pathological hallmark in the liver of patients with biliary atresia is ductular reaction, an expansion of new bile ductules that are thought to arise from conversion of mature hepatocytes. Here, we show that transcription factor GATA6 is a marker and potential driver of hepatocyte ductal metaplasia in biliary atresia. Hepatocyte GATA6 expression is elevated in biliary atresia, correlates with bile duct expansion, and decreases after successful portoenterostomy.

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

BACKGROUND & AIMS: Many pediatric patients with acute liver failure (PALF) do not receive a specific diagnosis (such as herpes simplex virus or Wilson disease or fatty acid oxidation defects)-they are left with an indeterminate diagnosis and are more likely to undergo liver transplantation, which is contraindicated for some disorders. Strategies to facilitate complete diagnostic testing should increase identification of specific liver diseases and might reduce liver transplantation. We investigated whether performing recommended age-specific diagnostic tests (AS-DTs) at the time of hospital admission reduces the percentage PALFs with an indeterminate diagnosis. METHODS: We performed a multinational observational cohort study of 658 PALF participants in the United States and Canada, enrolled at 10 medical centers, during 3 study phases from December 1999 through December 2014. A learning collaborative approach was used to implement AS-DT using an electronic medical record admission order set at hospital admission in phase 3 of the study. Data from 10 study sites participating in all 3 phases were compared before (phases 1 and 2) and after (phase 3) diagnostic test recommendations were inserted into electronic medical record order sets. RESULTS: The percentage of subjects with an indeterminate diagnosis decreased significantly between phases 1-2 (48.0%) and phase 3 (to 30.8%) (P = .0003). The 21-day cumulative incidence rates for liver transplantation were significantly different among phase 1 (34.6%), phase 2 (31.9%), and phase 3 (20.2%) (P = .030). The 21-day cumulative incidence rates for death did not differ significantly among phase 1 (17.9%), phase 2 (11.9%), and phase 3 (11.3%) (P = .20). CONCLUSIONS: In a multinational study of children with acute liver failure, we found that incorporating diagnostic test recommendations into electronic medical record order sets accessed at time of admission reduced the percentage with an indeterminate diagnosis that may have reduced liver transplants without increasing mortality. Widespread use of this approach could significantly enhance care of acute liver failure in children.

Salinity pulses interact with seasonal dry-down to increase ecosystem carbon loss in marshes of the Florida Everglades.

Coastal wetlands are globally important sinks of organic carbon (C). However, to what extent wetland C cycling will be affected by accelerated sea-level rise (SLR) and saltwater intrusion is unknown, especially in coastal peat marshes where water flow is highly managed. Our objective was to determine how the ecosystem C balance in coastal peat marshes is influenced by elevated salinity. For two years, we made monthly in situ manipulations of elevated salinity in freshwater (FW) and brackish water (BW) sites within Everglades National Park, Florida, USA. Salinity pulses interacted with marsh-specific variability in seasonal hydroperiods whereby effects of elevated pulsed salinity on gross ecosystem productivity (GEP), ecosystem respiration (ER), and net ecosystem productivity (NEP) were dependent on marsh inundation level. We found little effect of elevated salinity on C cycling when both marsh sites were inundated, but when water levels receded below the soil surface, the BW marsh shifted from a C sink to a C source. During these exposed periods, we observed an approximately threefold increase in CO2 efflux from the marsh as a result of elevated salinity. Initially, elevated salinity pulses did not affect Cladium jamaicense biomass, but aboveground biomass began to be significantly decreased in the saltwater amended plots after two years of exposure at the BW site. We found a 65% (FW) and 72% (BW) reduction in live root biomass in the soil after two years of exposure to elevated salinity pulses. Regardless of salinity treatment, the FW site was C neutral while the BW site was a strong C source (-334 to -454 g C·m-2 ·yr-1 ), particularly during dry-down events. A loss of live roots coupled with annual net CO2 losses as marshes transition from FW to BW likely contributes to the collapse of peat soils observed in the coastal Everglades. As SLR increases the rate of saltwater intrusion into coastal wetlands globally, understanding how water management influences C gains and losses from these systems is crucial. Under current Everglades' water management, drought lengthens marsh dry-down periods, which, coupled with saltwater intrusion, accelerates CO2 loss from the marsh.

Induced Pluripotent Stem Cell-Derived Hepatocytes and Precision Medicine in Human Liver Disease.

Liver-like human cells can be generated from human skin by converting fibroblasts to "induced pluripotent stem cells" (iPSCs), then differentiating the iPSCs into "induced hepatocytes". Although still primarily used as a research tool, emerging applications involving iPSC-derived induced hepatocytes have exciting and provocative clinical and translational potential. This review provides a brief summary of the current status of this field and obstacles that must be overcome before this novel tool will enable precision medicine-based approaches to human liver disease.

Data-Driven Modeling for Precision Medicine in Pediatric Acute Liver Failure.

Absence of early outcome biomarkers for Pediatric Acute Liver Failure (PALF) hinders medical and liver transplant decisions. We sought to define dynamic interactions among circulating inflammatory mediators to gain insights into PALF outcome sub-groups. Serum samples from 101 participants in the PALF study, collected over the first 7 days following enrollment, were assayed for 27 inflammatory mediators. Outcomes (Spontaneous survivors [S, n=61], Non-survivors [NS, n=12], and liver transplant patients [LTx, n=28]) were assessed at 21 days post-enrollment. Dynamic interrelations among mediators were defined using data-driven algorithms. Dynamic Bayesian Network inference identified a common network motif with HMGB1 as a central node in all patient sub-groups. The networks in S and LTx were similar, and differed from NS. Dynamic Network Analysis suggested similar dynamic connectivity in S and LTx, but a more highly-interconnected network in NS that increased with time. A Dynamic Robustness Index calculated to quantify how inflammatory network connectivity changes as a function of correlation stringency differentiated all three patient sub-groups. Our results suggest that increasing inflammatory network connectivity is associated with non-survival in PALF, and may ultimately lead to better patient outcome stratification.

Postponing the Hypoglycemic Response to Partial Hepatectomy Delays Mouse Liver Regeneration.

All serious liver injuries alter metabolism and initiate hepatic regeneration. Recent studies using partial hepatectomy (PH) and other experimental models of liver regeneration implicate the metabolic response to hepatic insufficiency as an important source of signals that promote regeneration. Based on these considerations, the analyses reported here were undertaken to assess the impact of interrupting the hypoglycemic response to PH on liver regeneration in mice. A regimen of parenteral dextrose infusion that delays PH-induced hypoglycemia for 14 hours after surgery was identified, and the hepatic regenerative response to PH was compared between dextrose-treated and control mice. The results showed that regenerative recovery of the liver was postponed in dextrose-infused mice (versus vehicle control) by an interval of time comparable to the delay in onset of PH-induced hypoglycemia. The regulation of specific liver regeneration-promoting signals, including hepatic induction of cyclin D1 and S-phase kinase-associated protein 2 expression and suppression of peroxisome proliferator-activated receptor γ and p27 expression, was also disrupted by dextrose infusion. These data support the hypothesis that alterations in metabolism that occur in response to hepatic insufficiency promote liver regeneration, and they define specific pro- and antiregenerative molecular targets whose regenerative regulation is postponed when PH-induced hypoglycemia is delayed.

Prevalence and Significance of Autoantibodies in Children With Acute Liver Failure.

OBJECTIVES: The purpose of the present study is to estimate autoantibody (auto-AB) frequency, clinical characteristics, and 21-day outcome of participants in the Pediatric Acute Liver Failure Study Group (PALFSG) by antinuclear antibody, smooth muscle antibody, and liver-kidney microsomal (LKM) antibody status. METHODS: Auto-ABs were determined at local and/or central laboratories. Subjects were assigned to autoimmune hepatitis (AIH), indeterminate, and other diagnoses groups. RESULTS: Between 1999 and 2010, 986 subjects were enrolled in the PALFSG. At least 1 auto-AB result was available for 722 (73.2%). At least 1 auto-AB was positive for 202 (28.0%). Diagnoses for auto-AB+ subjects were AIH (63), indeterminate (75), and other (64). Auto-ABs were more common in Wilson disease (12/32, 37.5%) compared with other known diagnoses (52/253, 20.6%, P = 0.03). LKM+ subjects were younger (median 2.4 vs 9.1 years, P < 0.001) and more likely to undergo liver transplantation (53.3% vs 31.4% P = 0.02) than other auto-AB+/LKM- subjects. Steroid treatment of subjects who were auto-AB+ was not significantly associated with survival and the subgroup with known diagnoses other than AIH had a higher risk of death. CONCLUSIONS: Auto-ABs are common in children with acute liver failure, occurring in 28%. Auto-AB+ subjects have similar outcomes to auto-AB negative subjects. LKM+ children are younger and more likely to undergo liver transplantation compared with other auto-AB+ subjects. Although auto-AB may indicate a treatable condition, positivity does not eliminate the need for a complete diagnostic evaluation because auto-ABs are present in other conditions. The significance of auto-AB in pediatric acute liver failure remains uncertain, but LKM+ appears to identify a unique population of children who merit further study.

Outcomes of Children With and Without Hepatic Encephalopathy From the Pediatric Acute Liver Failure Study Group.

OBJECTIVES: Hepatic encephalopathy (HE) is challenging to identify in children with acute liver failure and was not a requirement for enrollment into the Pediatric Acute Liver Failure Study Group (PALFSG). The outcomes of PALFSG participants presenting with and without HE are presented. METHODS: PALFSG participants were classified based on daily assessment of HE during the first 7 days following study enrollment: group 1-never developed HE; group 2-no HE at enrollment with subsequent HE development; and group 3-HE at study enrollment. Clinical and biochemical parameters and outcomes of death, spontaneous recovery, or liver transplantation were compared between groups. RESULTS: Data from 769 PALFSG (54% boys; median age 4.2 years; range 0-17.9 years) participants were analyzed, with 277 in group 1 (36%), 83 in group 2 (11%), and 409 in group 3 (53%). Mortality occurred in 11% of all participants and was highest among group 3 participants who demonstrated persistent grade III-IV HE (55%) or showed progression of HE (26%). Eleven (4%) group 1 participants died within 21 days of enrollment. Spontaneous recovery was highest in group 1 (79%) and lowest in group 2 (25%; P < 0.001). CONCLUSIONS: Mortality 21 days after enrollment was highest in participants enrolled with severe HE (grades III or IV) or demonstrating HE progression. Four percent of participants without recorded clinical HE in the 7 days after enrollment, however, died within 21 days. Improved assessment of neurological injury and pediatric acute liver failure prognostication schema are needed.

Elucidating the metabolic regulation of liver regeneration.

The regenerative capability of liver is well known, and the mechanisms that regulate liver regeneration are extensively studied. Such analyses have defined general principles that govern the hepatic regenerative response and implicated specific extracellular and intracellular signals as regulated during and essential for normal liver regeneration. Nevertheless, the most proximal events that stimulate liver regeneration and the distal signals that terminate this process remain incompletely understood. Recent data suggest that the metabolic response to hepatic insufficiency might be the proximal signal that initiates regenerative hepatocellular proliferation. This review provides an overview of the data in support of a metabolic model of liver regeneration and reflects on the clinical implications and areas for further study suggested by these findings.

Dietary aflatoxin-induced stunting in a novel rat model: evidence for toxin-induced liver injury and hepatic growth hormone resistance.

BACKGROUND: Despite a strong statistical correlation between dietary aflatoxin B1 (AFB1)-exposure and childhood stunting, the causal mechanism remains speculative. This issue is important because of emerging interest in reduction of human aflatoxin exposure to diminish the prevalence and complications of stunting. Pediatric liver diseases cause growth impairment, and AFB1 is hepatotoxic. Thus, liver injury might mediate AFB1-associated growth impairment. We have developed a rat model of dietary AFB1-induced stunting to investigate these questions. METHODS: Newly-weaned rats were given AFB1-supplemented- or control-diets from age 3-9 wk, and then euthanized for serum- and tissue-collection. Food intake and weight were serially assessed, with tibial-length determined at the experimental endpoint. Serum AFB1-adducts, hepatic gene and protein expression, and liver injury markers were quantified using established methodologies. RESULTS: AFB1-albumin adducts correlated with dietary toxin contamination, but such contamination did not affect food consumption. AFB1-exposed animals exhibited dose-dependent wasting and stunting, liver pathology, and suppression of hepatic targets of growth hormone (GH) signaling, but did not display increased mortality. CONCLUSION: These data establish toxin-dependent liver injury and hepatic GH-resistance as candidate mechanisms by which AFB1-exposure causes growth impairment in this mammalian model. Interrogation of modifiers of stunting using this model could guide interventions in at-risk and affected children.

Baseline Analysis of a Young α-1-Antitrypsin Deficiency Liver Disease Cohort Reveals Frequent Portal Hypertension.

OBJECTIVES: α-1-Antitrypsin (A1AT) deficiency is a common genetic disease with an unpredictable and highly variable course. The Childhood Liver Disease Research and Education Network is a National Institutes of Health, multicenter, longitudinal consortium studying pediatric liver diseases, with the objective of prospectively defining natural history and identifying disease modifiers. METHODS: Longitudinal, cohort study of A1AT patients' birth through 25 years diagnosed as having liver disease, type PIZZ or PISZ. Medical history, physical examination, laboratory, imaging, and standardized survey tool data were collected during the provision of standard of care. RESULTS: In the present report of the cohort at baseline, 269 subjects were enrolled between November 2008 and October 2012 (208 with their native livers and 61 postliver transplant). Subjects with mild disease (native livers and no portal hypertension [PHT]) compared to severe disease (with PHT or postliver transplant) were not different in age at presentation. A total of 57% of subjects with mild disease and 76% with severe disease were jaundiced at presentation (P = 0.0024). A total of 29% of subjects with native livers had PHT, but age at diagnosis and growth were not different between the no-PHT and PHT groups (P > 0.05). Subjects with native livers and PHT were more likely to have elevated bilirubin, ALT, AST, INR, and GGTP than the no-PHT group (P << 0.001), but overlap was large. Chemistries alone could not identify PHT. CONCLUSIONS: Many subjects with A1AT presenting with elevated liver tests and jaundice improve spontaneously. Subjects with PHT have few symptoms and normal growth. Longitudinal cohort follow-up will identify genetic and environmental disease modifiers.

Fibroblast growth factor 15 deficiency impairs liver regeneration in mice.

Fibroblast growth factor (FGF) 15 (human homolog, FGF19) is an endocrine FGF highly expressed in the small intestine of mice. Emerging evidence suggests that FGF15 is critical for regulating hepatic functions; however, the role of FGF15 in liver regeneration is unclear. This study assessed whether liver regeneration is altered in FGF15 knockout (KO) mice following 2/3 partial hepatectomy (PHx). The results showed that FGF15 KO mice had marked mortality, with the survival rate influenced by genetic background. Compared with wild-type mice, the KO mice displayed extensive liver necrosis and marked elevation of serum bile acids and bilirubin. Furthermore, hepatocyte proliferation was reduced in the KO mice because of impaired cell cycle progression. After PHx, the KO mice had weaker activation of signaling pathways that are important for liver regeneration, including signal transducer and activator of transcription 3, nuclear factor-κB, and mitogen-activated protein kinase. Examination of the KO mice at early time points after PHx revealed a reduced and/or delayed induction of immediate-early response genes, including growth-control transcription factors that are critical for liver regeneration. In conclusion, the results suggest that FGF15 deficiency severely impairs liver regeneration in mice after PHx. The underlying mechanism is likely the result of disrupted bile acid homeostasis and impaired priming of hepatocyte proliferation.

Characterization of the regulation and function of zinc-dependent histone deacetylases during rodent liver regeneration.

UNLABELLED: The studies reported here were undertaken to define the regulation and functional importance of zinc-dependent histone deacetylase (Zn-HDAC) activity during liver regeneration using the mouse partial hepatectomy (PH) model. The results showed that hepatic HDAC activity was significantly increased in nuclear and cytoplasmic fractions following PH. Further analyses showed isoform-specific effects of PH on HDAC messenger RNA (mRNA) and protein expression, with increased expression of the class I HDACs, 1 and 8, and class II HDAC4 in regenerating liver. Hepatic expression of (class II) HDAC5 was unchanged after PH; however, HDAC5 exhibited transient nuclear accumulation in regenerating liver. These changes in hepatic HDAC expression, subcellular localization, and activity coincided with diminished histone acetylation in regenerating liver. The significance of these events was investigated by determining the effects of suberoylanilide hydroxyamic acid (SAHA, a specific inhibitor of Zn-HDAC activity) on hepatic regeneration. The results showed that SAHA treatment suppressed the effects of PH on histone deacetylation and hepatocellular bromodeoxyuridine (BrdU) incorporation. Further examination showed that SAHA blunted hepatic expression and activation of cell cycle signals downstream of induction of cyclin D1 expression in mice subjected to PH. CONCLUSION: The data reported here demonstrate isoform-specific regulation of Zn-HDAC expression, subcellular localization, and activity in regenerating liver. These studies also indicate that HDAC activity promotes liver regeneration by regulating hepatocellular cell cycle progression at a step downstream of cyclin D1 induction.