Cell death is a natural process for the turnover of aged cells, but it can also arise as a result of pathological conditions. Cell death is recognized as a key feature in both acute and chronic hepatobiliary diseases caused by drug, alcohol, and fat uptake; by viral infection; or after surgical intervention. In the case of chronic disease, cell death can lead to (chronic) secondary inflammation, cirrhosis, and the progression to liver cancer. In liver transplantation, graft preservation and ischemia/reperfusion injury are associated with acute cell death. In both cases, so‐called programmed cell death modalities are involved. Several distinct types of programmed cell death have been described of which apoptosis and necroptosis are the most well known. Parenchymal liver cells, including hepatocytes and cholangiocytes, are susceptible to both apoptosis and necroptosis, which are triggered by distinct signal transduction pathways. Apoptosis is dependent on a proteolytic cascade of caspase enzymes, whereas necroptosis induction is caspase‐independent. Moreover, different from the “silent” apoptotic cell death, necroptosis can cause a secondary inflammatory cascade, so‐called necroinflammation, triggered by the release of various damage‐associated molecular patterns (DAMPs). These DAMPs activate the innate immune system, leading to both local and systemic inflammatory responses, which can even cause remote organ failure. Therapeutic targeting of necroptosis by pharmacological inhibitors, such as necrostatin‐1, shows variable effects in different disease models.

Background & Aims Liver and bile duct diseases often are associated with extensive cell death of cholangiocytes. Necroptosis represents a common mode of programmed cell death in cholangiopathy, however, detailed mechanistic knowledge is limited owing to the lack of appropriate in vitro models. To address this void, we investigated whether human intrahepatic cholangiocyte organoids (ICOs) can recapitulate cholangiopathy-associated necroptosis and whether this model can be used for drug screening. Methods We evaluated the clinical relevance of necroptosis in end-stage liver diseases and liver transplantation by immunohistochemistry. Cholangiopathy-associated programmed cell death was evoked in ICOs derived from healthy donors or patients with primary sclerosing cholangitis or alcoholic liver diseases by the various stimuli. Results The expression of key necroptosis mediators, receptor-interacting protein 3 and phosphorylated mixed lineage kinase domain-like, in cholangiocytes during end-stage liver diseases was confirmed. The phosphorylated mixed lineage kinase domain-like expression was etiology-dependent. Gene expression analysis confirmed that primary cholangiocytes are more prone to necroptosis compared with primary hepatocytes. Both apoptosis and necroptosis could be specifically evoked using tumor necrosis factor α and second mitochondrial-derived activator of caspases mimetic, with or without caspase inhibition in healthy and patient-derived ICOs. Necroptosis also was induced by ethanol metabolites or human bile in ICOs from donors and patients. The organoid cultures further uncovered interdonor variable and species-specific drug responses. Dabrafenib was identified as a potent necroptosis inhibitor and showed a protective effect against ethanol metabolite toxicity. Conclusions Human ICOs recapitulate cholangiopathy-associated necroptosis and represent a useful in vitro platform for the study of biliary cytotoxicity and preclinical drug evaluation.

Oxidative stress is one of the key mechanisms affecting the outcome throughout the course of organ transplantation. It is widely believed that the redox balance is dysregulated during ischemia and reperfusion (I/R) and causes subsequent oxidative injury, resulting from the formation of reactive oxygen species (ROS). Moreover, in order to alleviate organ shortage, increasing number of grafts is retrieved from fatty, older, and even non-heart-beating donors that are particularly vulnerable to the accumulation of ROS. To improve the viability of grafts and reduce the risk of posttransplant dysfunction, a large number of studies have been done focusing on the antioxidant treatments for the purpose of maintaining the redox balance and thereby protecting the grafts. This review provides an overview of these emerging antioxidant treatments, targeting donor, graft preservation, and recipient as well.

Circulating tumor cells (CTCs) serves a primary function in metastasis and recurrence of hepatocellular carcinoma (HCC). In the present study, in order to evaluate the analytical performance and clinical value of the liquid biopsy-based platform, a novel integrated subtraction enrichment and immunostaining-fluorescence in situ hybridization (iFISH®) platform was applied to analyze CTCs in patients with HCC undergoing liver transplantation (LT). In total, 30 patients with HCC undergoing LT and 10 healthy volunteers were enrolled. CTCs in peripheral blood that were obtained from each patient prior to LT and 3 months thereafter were detected using the iFISH® platform, and CellSearch® system was performed for each subject for comparison. Using iFISH® and CellSearch®, the percentage of CTCs in patients with pre-operative HCC were 70.00% and 26.67%, respectively. CTCs counted using iFISH® (iFISH-CTCs) were increased compared with CellSearch® (Cellsearch-CTCs) (P<0.01). A significant decrease in iFISH-CTCs was observed 3 months following LT (3.04±0.93/7.5 to 1.0±0.53/7.5 ml, P<0.05). Furthermore, patients with lower preoperative iFISH-CTCs level (<5/7.5 ml) had markedly increased recurrence-free survival compared with iFISH-CTCs (>5/7.5 ml, 15 vs. 5.5 months; P<0.01. iFISH® platform exhibits an increased analytical sensitivity, and may be used as a dynamic monitoring tool for CTCs, and CTCs may be a good prognostic indicator for patients with HCC undergoing LT.

Mitochondria are essential organelles for cellular energy and metabolism. Like with any organ, the liver highly depends on the function of these cellular powerhouses. Hepatotoxic insults often lead to an impairment of mitochondrial activity and an increase in oxidative stress, thereby compromising the metabolic and synthetic functions. Mitochondria play a critical role in ATP synthesis and the production or scavenging of free radicals. Mitochondria orchestrate many cellular signaling pathways involved in the regulation of cell death, metabolism, cell division, and progenitor cell differentiation. Mitochondrial dysfunction and oxidative stress are closely associated with ischemia-reperfusion injury during organ transplantation and with different liver diseases, including cholestasis, steatosis, viral hepatitis, and drug-induced liver injury. To develop novel mitochondria-targeting therapies or interventions, a better understanding of mitochondrial dysfunction and oxidative stress in hepatic pathogenesis is very much needed. Therapies targeting mitochondria impairment and oxidative imbalance in liver diseases have been extensively studied in preclinical and clinical research. In this review, we provide an overview of how oxidative stress and mitochondrial dysfunction affect liver diseases and liver transplantation. Furthermore, we summarize recent developments of antioxidant and mitochondria-targeted interventions.

Fatty liver disease has grown into a major global health burden, attributed to multi-factors including sedentary lifestyle, obesogenic diet and prevalence of metabolic disorders. The lack of robust experimental models is hampering the research and therapeutic development for fatty liver disease. This study aims to develop an organoid-based 3D culture model to recapitulate key features of fatty liver disease focusing on intracellular lipid accumulation and metabolic dysregulation. We used human liver-derived intrahepatic cholangiocyte organoids and hepatocyte differentiated organoids. These organoids were exposed to lactate, pyruvate, and octanoic acid (LPO) for inducing lipid accumulation and mitochondrial impairment. Lipid accumulation resulted in alternations of gene transcription with major effects on metabolic pathways, including triglyceride and glucose level increase, which is consistent with metabolic changes in fatty liver disease patients. Interestingly, lipid accumulation affected mitochondria as shown by morphological transitions, alternations in expression of mitochondrial encoded genes, and reduction of ATP production. Meanwhile, we found treatment with obeticholic acid and metformin can alleviate fat accumulation in organoids. This study demonstrated that LPO exposure can induce lipid accumulation and associated metabolic dysregulation in human liver-derived organoids. This provides an innovative model for studying fatty liver disease and testing potential therapeutics.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Abbreviations: BA, biliary atresia; HMGB1, high mobility group box protein 1; ICO, human cholangiocyte organoid With great interest, we read the study by Mohanty S et al. (1) demonstrating that rotavirus-infected cholangiocytes actively release high mobility group box protein 1 (HMGB1), contributing to the pathogenesis of biliary atresia (BA). The activation of HMGB1 secretion involves viral induction of reactive oxygen species and is mediated by the p38/STAT1 axis. Moreover, the level of serum HMGB1 at the time of Kasai portoenterostomy could help identify BA patients who are potentially responsive to anti-inflammatory administration. After reading the publication carefully, we would like to add a few comments.