Hepatology

Acute on chronic liver failure (ACLF) is the culmination of chronic liver disease and extrahepatic organ failures, which is associated with a high short‐term mortality and immense health care expenditure. There are varying definitions for organ failures and ACLF in Europe, North America, and Asia. These differing definitions need to be reconciled to enhance progress in the field. The pathogenesis of ACLF is multifactorial and related to interactions between the immunoinflammatory system, microbiota, and the various precipitating factors. Individual organ failures related to the kidney, brain, lungs, and circulation have cumulative adverse effects on mortality and are often complicated or precipitated by infections. Strategies to prevent and rapidly treat these organ failures are paramount in improving survival. With the aging population and paucity of organs for liver transplant, the prognosis of ACLF patients is poor, highlighting the need for novel therapeutic strategies. The role of liver transplant in ACLF is evolving and needs further investigation across large consortia. A role for early palliative care and management of frailty as approaches to alleviate disease burden and improve patient‐reported outcomes is being increasingly recognized.

Conclusion: ACLF is a clinically relevant syndrome that is epidemic worldwide and requires a dedicated multinational approach focused on prognostication and management; investigations are underway worldwide to prepare ACLF for prime time. (Hepatology 2018; 00:000‐000)

Lipocalin‐2 (LCN2), also known as neutrophil gelatinase‐associated lipocalin (NGAL), a key antibacterial protein, is highly elevated in patients with end‐stage liver disease that is often associated with bacterial infection. LCN2 is expressed at high levels in both hepatocytes and neutrophils; however, how hepatocyte‐derived and neutrophil‐derived LCN2 cooperate to combat bacterial infection remains unclear. Here, by studying hepatocyte‐specific and myeloid‐specific Lcn2 knockout mice in two models of systemic and local Klebsiella pneumoniae infections, we demonstrated that hepatocytes played a critical role in controlling systemic infection by secreting LCN2 protein into the circulation following intraperitoneal injection of bacteria, whereas neutrophils were more important in combating local lung infection by carrying LCN2 in their specific granules to the local infection site following intratracheal intubation of bacteria. Both hepatocyte‐derived and myeloid cell–derived LCN2 were required against bacterial infection in the peritoneal cavity and liver necrotic areas following intraperitoneal injection of Klebsiella pneumoniae. LCN2/NGAL protein was detected in neutrophil extracellular traps (NETs) in activated neutrophils from mice and humans. Disruption of the Lcn2 gene in neutrophils abolished LCN2 on NETs, whereas deletion of this gene in hepatocytes did not affect LCN2 protein on NETs. Genetic deletion of the Lcn2 gene globally or specifically in neutrophils did not affect NET formation but reduced the bactericidal effect of NETs in vitro. Finally, NGAL‐positive NETs were detected in the liver from patients with various types of liver diseases. Conclusion: Both hepatocytes and neutrophils combat bacterial infection through the production of LCN2; extracellular LCN2 secreted by hepatocytes limits systemic bacterial infection, whereas neutrophils carry LCN2 protein to the local site and against local bacterial infection through NETs. (Hepatology 2018).

Severe alcoholic hepatitis (SAH) is often a progressive disease with high mortality and limited steroid responsiveness. Management options of steroid nonresponsive SAH (day 7 Lille score > 0.45) are limited. We assessed the efficacy and safety of granulocyte colony‐stimulating factor (G‐CSF) in steroid nonresponders. A randomized, double‐blind, single‐center trial (NCT01820208) was conducted between March 2013 and June 2016 in patients with histologically proven SAH, nonresponsive to 40 mg/day of prednisolone were randomized to G‐CSF (12 doses, 300 μg each in 28 days) or placebo. Responders were continued with prednisolone. Of the 430 patients with SAH, 132 received steroid therapy. Of these, 33 (25%) were nonresponders and were randomized to G‐CSF or placebo (14 in each group after exclusions). The baseline characteristics of both groups were comparable. The 28‐day mortality was comparable between the groups (21.4%, G‐CSF; 28.6%, placebo; P = 0.69). At 90 days, in the G‐CSF but not in the placebo group, the Model for End‐Stage Liver Disease reduced from 24.6 ± 3.9 to 19.4 ± 3.7 (P = 0.002) and Maddrey’s discriminant function from 74.8 ± 22.8 to 57.4 ± 31 (P = 0.26). Infections were less common (28% versus 71%; P < 0.001) with lower 90‐day mortality (35.7% versus 71.4%; P = 0.04) in the G‐CSF than in the placebo group. On Cox regression analysis, receiving G‐CSF (hazard ratio, 0.37; SD, 0.14‐0.98; P = 0.04), and high baseline serum creatinine (hazard ratio, 4.12; SD, 1.7‐10.3; P = 0.002) predicted day‐90 outcomes in steroid nonresponsive SAH. Patients tolerated G‐CSF without any major adverse events. Conclusion: Approximately one‐quarter of patients with SAH do not respond to corticosteroid therapy. Administration of G‐CSF is safe and helps to reduce the disease severity and 90‐day mortality in these patients.

In contrast to all other organs, liver‐to‐body‐weight ratio needs to be maintained always at 100% of what is required for body homeostasis. Adjustment of liver size to 100% of what is required for homeostasis has been called “hepatostat.” Removal of a portion of any other organ is followed with local regeneration of a limited degree, but it never attempts to reach 100% of the original size. The complex mechanisms involved in this uniquely hepatic process encompass a variety of regenerative pathways that are specific to different types of injury. The most studied form of liver regeneration (LR) is that occurring after loss of hepatocytes in a single acute injury, such as rodent LR after two‐thirds partial hepatectomy or administration of damaging chemicals (CCl₄, acetaminophen, etc.). Alternative regenerative pathways become activated when normal regeneration is thwarted and trigger the appearance of “progenitor” cells. Chronic loss of hepatocytes is associated with regenerative efforts characterized by continual hepatocyte proliferation and often has adverse consequences (development of cirrhosis or liver cancer). Even though a very few hepatocytes proliferate at any given time in normal liver, the mechanisms involved in the maintenance of liver weight by this slow process in the absence of liver injury are not as well understood. (Hepatology 2017;65:1384‐1392)