Ectopic lymphoid structures function as microniches for tumor progenitor cells in hepatocellular carcinoma.

Ectopic lymphoid-like structures (ELSs) are often observed in cancer, yet their function is obscure. Although ELSs signify good prognosis in certain malignancies, we found that hepatic ELSs indicated poor prognosis for hepatocellular carcinoma (HCC). We studied an HCC mouse model that displayed abundant ELSs and found that they constituted immunopathological microniches wherein malignant hepatocyte progenitor cells appeared and thrived in a complex cellular and cytokine milieu until gaining self-sufficiency. The egress of progenitor cells and tumor formation were associated with the autocrine production of cytokines previously provided by the niche. ELSs developed via cooperation between the innate immune system and adaptive immune system, an event facilitated by activation of the transcription factor NF-κB and abolished by depletion of T cells. Such aberrant immunological foci might represent new targets for cancer therapy.

Banff 2022 Liver Group Meeting report: Monitoring long-term allograft health.

The Banff Working Group on Liver Allograft Pathology met in September 2022. Participants included hepatologists, surgeons, pathologists, immunologists, and histocompatibility specialists. Presentations and discussions focused on the evaluation of long-term allograft health, including noninvasive and tissue monitoring, immunosuppression optimization, and long-term structural changes. Potential revision of the rejection classification scheme to better accommodate and communicate late T cell-mediated rejection patterns and related structural changes, such as nodular regenerative hyperplasia, were discussed. Improved stratification of long-term maintenance immunosuppression to match the heterogeneity of patient settings will be central to improving long-term patient survival. Such personalized therapeutics are in turn contingent on a better understanding and monitoring of allograft status within a rational decision-making approach, likely to be facilitated in implementation with emerging decision-support tools. Proposed revisions to rejection classification emerging from the meeting include the incorporation of interface hepatitis and fibrosis staging. These will be opened to online testing, modified accordingly, and subject to consensus discussion leading up to the next Banff conference.

Incidental Gastric Signet Ring Cell Carcinoma: A Call for an Aggressive Approach.

BACKGROUND: Signet ring cell carcinoma (SRCC) is classified as an undifferentiated gastric carcinoma with poor prognosis. Early SRCCs are associated with improved prognosis. OBJECTIVES: To describe the outcomes of incidental SRCC. METHODS: In this case series, 900 medical charts of patients with SRCC were screened to identify patients with incidental SRCC, defined as diagnosed in random, non-focal-lesion-targeted biopsies. RESULTS: Six patients were diagnosed with incidental SRCC and underwent gastrectomy. The final pathology of five patients revealed one or more small foci of early SRCC without lymphovascular invasion. Only one patient had no evidence of malignancy. The median follow-up after surgery was 4.2 years (50 months, range 37-90 months). No deaths or recurrences were recorded during the follow-up period. These results resemble the reported survival rate for early SRCC. CONCLUSIONS: An aggressive surgical approach in incidental gastric SRCC patients is recommended, as they have a chance for long-term survival.

Lack of galectin-1 exacerbates chronic hepatitis, liver fibrosis, and carcinogenesis in murine hepatocellular carcinoma model.

Chronic liver inflammation (CLI) is a risk factor for development of hepatocellular carcinoma (HCC). Galectin-1 (Gal1) is involved in the regulation of inflammation, angiogenesis, and tumorigenesis, exhibiting multiple anti-inflammatory and protumorigenic activities. We aimed to explore its regulatory role in CLI and HCC progression using an established model of CLI-mediated HCC development, Abcb4 [multidrug-resistance 2 (Mdr2)]-knockout (KO) mice, which express high levels of Gal1 in the liver. We generated double-KO (dKO) Gal1-KO/Mdr2-KO mice on C57BL/6 and FVB/N genetic backgrounds and compared HCC development in the generated strains with their parental Mdr2-KO strains. Loss of Gal1 increased liver injury, inflammation, fibrosis, and ductular reaction in dKO mice of both strains starting from an early age. Aged dKO mutants displayed earlier hepatocarcinogenesis and increased tumor size compared with control Mdr2-KO mice. We found that osteopontin, a well-known modulator of HCC development, and oncogenic proteins Ntrk2 (TrkB) and S100A4 were overexpressed in dKO compared with Mdr2-KO livers. Our results demonstrate that in Mdr2-KO mice, a model of CLI-mediated HCC, Gal1-mediated protection from hepatitis, liver fibrosis, and HCC initiation dominates over its known procarcinogenic activities at later stages of HCC development. These findings suggest that anti-Gal1 treatments may not be applicable at all stages of CLI-mediated HCC.-Potikha, T., Pappo, O., Mizrahi, L., Olam, D., Maller, S. M., Rabinovich, G. A., Galun, E., Goldenberg, D. S. Lack of galectin-1 exacerbates chronic hepatitis, liver fibrosis, and carcinogenesis in murine hepatocellular carcinoma model.

miRNA-132 induces hepatic steatosis and hyperlipidaemia by synergistic multitarget suppression.

OBJECTIVE: Both non-alcoholic fatty liver disease (NAFLD) and the multitarget complexity of microRNA (miR) suppression have recently raised much interest, but the in vivo impact and context-dependence of hepatic miR-target interactions are incompletely understood. Assessing the relative in vivo contributions of specific targets to miR-mediated phenotypes is pivotal for investigating metabolic processes. DESIGN: We quantified fatty liver parameters and the levels of miR-132 and its targets in novel transgenic mice overexpressing miR-132, in liver tissues from patients with NAFLD, and in diverse mouse models of hepatic steatosis. We tested the causal nature of miR-132 excess in these phenotypes by injecting diet-induced obese mice with antisense oligonucleotide suppressors of miR-132 or its target genes, and measured changes in metabolic parameters and transcripts. RESULTS: Transgenic mice overexpressing miR-132 showed a severe fatty liver phenotype and increased body weight, serum low-density lipoprotein/very low-density lipoprotein (LDL/VLDL) and liver triglycerides, accompanied by decreases in validated miR-132 targets and increases in lipogenesis and lipid accumulation-related transcripts. Likewise, liver samples from both patients with NAFLD and mouse models of hepatic steatosis or non-alcoholic steatohepatitis (NASH) displayed dramatic increases in miR-132 and varying decreases in miR-132 targets compared with controls. Furthermore, injecting diet-induced obese mice with anti-miR-132 oligonucleotides, but not suppressing its individual targets, reversed the hepatic miR-132 excess and hyperlipidemic phenotype. CONCLUSIONS: Our findings identify miR-132 as a key regulator of hepatic lipid homeostasis, functioning in a context-dependent fashion via suppression of multiple targets and with cumulative synergistic effects. This indicates reduction of miR-132 levels as a possible treatment of hepatic steatosis.

The Effects of Chronic Iron Overload in Rats with Acute Acetaminophen Overdose.

BACKGROUND AND AIMS: Rats are resistant to acetaminophen (APAP) hepatotoxicity. In this study, we evaluated whether by augmentation of the hepatic oxidative stress, through the induction of hepatic iron overload (IO), it will be feasible to overcome the resistance of rats to the toxic effects of APAP. METHOD: Rats with no or increased hepatic IO. RESULTS: Providing iron by diet induced hepatocellular IO, while parenteral iron administration induced combined hepatocellular and sinusoidal cell IO. APAP administration to rats with no IO caused an increase in hepatic oxidative stress and a decrease in the hepatic antioxidative markers but no hepatic cell damage. APAP administration to rats with hepatocellular IO further amplified the hepatic oxidative stress but induced only hepatocyte feathery degeneration without any increase in serum aminotransaminases. APAP administration to rats with combined hepatocellular and sinusoidal cell IO caused an unexpected decrease in hepatic oxidative stress and increase in the hepatic antioxidative markers and no hepatic cell damage. No hepatic expression of activated c-jun-N-terminal kinase was detected in any of the rats. CONCLUSIONS: The hepatic distribution of iron may affect its oxidative/antioxidative milieu. Augmentation of hepatic oxidative stress did not increase the rats' vulnerability to APAP.

ADAR1 deletion induces NFκB and interferon signaling dependent liver inflammation and fibrosis.

Adenosine deaminase acting on RNA (ADAR) 1 binds and edits double-stranded (ds) RNA secondary structures found mainly within untranslated regions of many transcripts. In the current research, our aim was to study the role of ADAR1 in liver homeostasis. As previous studies show a conserved immunoregulatory function for ADAR1 in mammalians, we focused on its role in preventing chronic hepatic inflammation and the associated activation of hepatic stellate cells to produce extracellular matrix and promote fibrosis. We show that hepatocytes specific ADAR1 knock out (KO) mice display massive liver damage with multifocal inflammation and fibrogenesis. The bioinformatics analysis of the microarray gene-expression datasets of ADAR1 KO livers reveled a type-I interferons signature and an enrichment for immune response genes compared to control littermate livers. Furthermore, we found that in vitro silencing of ADAR1 expression in HepG2 cells leads to enhanced transcription of NFκB target genes, foremost of the pro-inflammatory cytokines IL6 and IL8. We also discovered immune cell-independent paracrine signaling among ADAR1-depleted HepG2 cells and hepatic stellate cells, leading to the activation of the latter cell type to adopt a profibrogenic phenotype. This paracrine communication dependent mainly on the production and secretion of the cytokine IL6 induced by ADAR1 silencing in hepatocytes. Thus, our findings shed a new light on the vital regulatory role of ADAR1 in hepatic immune homeostasis, chiefly its inhibitory function on the crosstalk between the NFκB and type-I interferons signaling cascades, restraining the development of liver inflammation and fibrosis.

Positive antimitochondrial antibody but normal serum alkaline phosphatase levels: Could it be primary biliary cholangitis?

AIM: Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease, typically diagnosed by elevated cholestatic liver enzymes and a positive antimitochondrial antibody (AMA) test. The clinical significance of AMA positivity in patients with normal cholestatic liver enzymes is uncertain. METHODS: Charts of patients with normal cholestatic liver enzymes and AMA positivity who underwent liver biopsy between 2012 and 2015 were retrospectively analyzed. RESULTS: Six AMA-positive patients with normal cholestatic liver enzymes who underwent a liver biopsy were identified. Four (67%) showed florid bile duct lesion compatible with early-stage PBC, whereas the other two showed mild and non-specific histological findings. The patients with histological findings compatible with PBC had higher enzyme-linked immunosorbent assay-determined AMA titers and significantly elevated immunoglobulin M (IgM) level. Patients with non-specific histological findings (33%) had low-titer AMA and a borderline elevated IgM level. CONCLUSIONS: Antimitochondrial antibody-positive patients with normal cholestatic liver enzymes should be meticulously evaluated for PBC including a liver biopsy, mainly in patients with high-titer seropositivity for AMA and a significantly elevated IgM level. More studies are required to clarify the role of liver biopsy in these patients and further follow-up may elucidate the relationship of these patients to those with more classical forms of PBC.

Acquisition of an immunosuppressive protumorigenic macrophage phenotype depending on c-Jun phosphorylation.

The inflamed tumor microenvironment plays a critical role in tumorigenesis. However, the mechanisms through which immune cells, particularly macrophages, promote tumorigenesis have only been partially elucidated, and the full scope of signaling pathways supplying macrophages with protumorigenic phenotypes still remain largely unknown. Here we report that germ-line absence of c-Jun N-terminal phosphorylation at serines 63 and 73 impedes inflammation-associated hepatocarcinogenesis, yet deleting c-Jun only in hepatocytes does not inhibit hepatocellular carcinoma (HCC) formation. Moreover, in human HCC-bearing livers, c-Jun phosphorylation is found in inflammatory cells, whereas it is mostly absent from malignant hepatocytes. Interestingly, macrophages in livers of mice with chronic hepatitis gradually switch their phenotype along the course of disease. Macrophage phenotype and density are dictated by c-Jun phosphorylation, in vitro and in vivo. Transition of macrophage phenotype, from antitumorigenic to protumorigenic, occurs before tumorigenesis, resulting in the production of various chemokines, including chemokine (C-C motif) ligand 17 (CCL17) and CCL22. Such signals, emanating from the liver microenvironment, direct the recruitment of regulatory T cells, which are known to facilitate HCC growth. Our findings identify c-Jun phosphorylation as a key mediator of macrophage education and point to the recruitment of immunosuppressive regulatory T cells as a possible protumorigenic mechanism.

Gastric Polyp Growth during Endoscopic Surveillance for Esophageal Varices or Barrett's Esophagus.

BACKGROUND: We recently observed patients with chronic liver disease (CLD) or chronic reflux symptoms (CRS) who developed gastric polyps (GPs) while undergoing surveillance gastroscopies for the detection of esophageal varices or Barrett's esophagus, respectively. OBJECTIVES: To identify risk factors for GP growth and estimate its growth rate. METHODS: GP growth rate was defined as the number of days since the first gastroscopy (without polyps) in the surveillance program, until the gastroscopy when a GP was discovered. RESULTS: Gastric polyp growth rates in CLD and CRS patients were similar. However, hyperplastic gastric polyps (HGPs) were detected more often (87.5% vs. 60.5%, P = 0.051) and at a higher number (2.57 ± 1.33 vs. 1.65 ± 0.93, P = 0.021) in the CLD patients. Subgroup analysis revealed the following findings only in CLD patients with HGPs: (i) a positive correlation between the GP growth rate and the patient's age; the older the patient, the higher the GP growth rate (r = 0.7, P = 0.004). (ii) A negative correlation between the patient's age and the Ki-67 proliferation index value; the older the patient, the lower the Ki-67 value (r = -0.64, P = 0.02). No correlation was detected between Ki-67 values of HGPs in CLD patients and the presence of portal hypertension, infection with Helicobacter pylori, or proton pump inhibitor use. CONCLUSIONS: In comparison with CRS patients, CLD patients developed HGPs more often and at a greater number. Young CLD patients may have a tendency to develop HGPs at a faster rate than elderly CLD patients.

Ultra Low Dose Delta 9-Tetrahydrocannabinol Protects Mouse Liver from Ischemia Reperfusion Injury.

BACKGROUND/AIMS: Ischemia/reperfusion (I/R) injury is the main cause of both primary graft dysfunction and primary non-function of liver allografts. Cannabinoids has been reported to attenuate myocardial, cerebral and hepatic I/R oxidative injury. Delta-9-tetrahydrocannabinol (THC), a cannabinoid agonist, is the active components of marijuana. In this study we examined the role of ultralow dose THC (0.002mg/kg) in the protection of livers from I/R injury. This extremely low dose of THC was previously found by us to protect the mice brain and heart from a variety of insults. METHODS: C57Bl Mice were studied in in vivo model of hepatic segmental (70%) ischemia for 60min followed by reperfusion for 6 hours. RESULTS: THC administration 2h prior to the induction of hepatic I/R was associated with significant attenuated elevations of: serum liver transaminases ALT and AST, the hepatic oxidative stress (activation of the intracellular signaling CREB pathway), the acute proinflammatory response (TNF-α, IL-1α, IL-10 and c-FOS hepatic mRNA levels, and ERK signaling pathway activation). This was followed by cell death (the cleavage of the pro-apoptotic caspase 3, DNA fragmentation and TUNEL) after 6 hours of reperfusion. Significantly less hepatic injury was detected in the THC treated I/R mice and fewer apoptotic hepatocytes cells were identified by morphological criteria compared with untreated mice. CONCLUSION: A single ultralow dose THC can reduce the apoptotic, oxidative and inflammatory injury induced by hepatic I/R injury. THC may serve as a potential target for therapeutic intervention in hepatic I/R injury during liver transplantation, liver resection and trauma.

Interstrain differences in chronic hepatitis and tumor development in a murine model of inflammation-mediated hepatocarcinogenesis.

UNLABELLED: Chronic inflammation is strongly associated with an increased risk for hepatocellular carcinoma (HCC) development. The multidrug resistance 2 (Mdr2)-knockout (KO) mouse (adenosine triphosphate-binding cassette b4(-/-) ), a model of inflammation-mediated HCC, develops chronic cholestatic hepatitis at an early age and HCC at an adult age. To delineate factors contributing to hepatocarcinogenesis, we compared the severity of early chronic hepatitis and late HCC development in two Mdr2-KO strains: Friend virus B-type/N (FVB) and C57 black 6 (B6). We demonstrated that hepatocarcinogenesis was significantly less efficient in the Mdr2-KO/B6 mice versus the Mdr2-KO/FVB mice; this difference was more prominent in males. Chronic hepatitis in the Mdr2-KO/B6 males was more severe at 1 month of age but was less severe at 3 months of age in comparison with age-matched Mdr2-KO/FVB males. A comparative genome-scale gene expression analysis of male livers of both strains at 3 months of age revealed both common and strain-specific aberrantly expressed genes, including genes associated with the regulation of inflammation, the response to oxidative stress, and lipid metabolism. One of these regulators, galectin-1 (Gal-1), possesses both anti-inflammatory and protumorigenic activities. To study its regulatory role in the liver, we transferred the Gal-1-KO mutation (lectin galactoside-binding soluble 1(-/-) ) from the B6 strain to the FVB strain, and we demonstrated that endogenous Gal-1 protected the liver against concanavalin A-induced hepatitis with the B6 genetic background but not the FVB genetic background. CONCLUSION: Decreased chronic hepatitis in Mdr2-KO/B6 mice at the age of 3 months correlated with a significant retardation of liver tumor development in this strain versus the Mdr2-KO/FVB strain. We found candidate factors that may determine strain-specific differences in the course of chronic hepatitis and HCC development in the Mdr2-KO model, including inefficient anti-inflammatory activity of the endogenous lectin Gal-1 in the FVB strain.

Endomyocardial biopsy in clinical practice: the diagnostic yield and insights from a 5-year single-center experience.

OBJECTIVES: Endomyocardial biopsy (EMB) is a diagnostic tool for evaluating various cardiac conditions, such as myocarditis and myocardial infiltrative diseases. It is also the gold standard screening technique for detecting allograft rejection after heart transplantation. Despite advances in noninvasive imaging modalities for myocardial tissue characterization, EMB is still necessary for making a definitive diagnosis and determining treatment for certain conditions. Herein, we report our recent experience using EMB and its diagnostic yield. METHODS AND RESULTS: We retrospectively reviewed EMBs performed at our institution from March 2018 through March 2023. Clinical data, including patient characteristics, indication and diagnostic yield of EMB, and procedure-related complications, were collected. Histopathological findings of the biopsies were recorded and classified based on the degree to which they matched the clinical diagnosis and cardiac magnetic resonance imaging (CMR) findings. A total of 212 EMBs obtained in 178 consecutive patients were retrospectively analyzed, with 42 biopsies performed for allograft rejection surveillance (10 patients) and the remaining performed for presumptive diagnosis of acute myocarditis or unexplained cardiomyopathy. Among the non-heart transplant cases, 54.7% of EMBs provided a clear diagnosis. The most common diagnosis was myocarditis (69%), followed by cardiac amyloidosis (CA) (26%). EMB was also helpful in detecting several rare cardiac conditions, such as eosinophilic granulomatosis with polyangiitis (EGPA), Fabry disease, and cardiac sarcoidosis. In a cohort of 101 patients who underwent both CMR and EMB, the results were concordant in 66% of cases. However, in 24.7% of patients, EMB was able to identify pathological conditions where CMR results were inconclusive, highlighting its complementary role in determining an accurate diagnosis. No complications were reported in any of the 212 EMBs performed. CONCLUSIONS: With advances in cardiac imaging modalities, EMB is not routinely indicated for the diagnosis of cardiomyopathy. However, EMB is still an important tool for diagnosing specific cardiac diseases and could be crucial for confirming the diagnosis. EMB is generally safe if performed at experienced centers.

Incorporating artificial intelligence in portable infrared thermal imaging for the diagnosis and staging of nonalcoholic fatty liver disease.

Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) is one of the most prevalent chronic liver diseases worldwide. Thermal imaging combined with advanced image-processing and machine learning analysis accurately classified disease status in a study on mice; this study aimed to develop this tool for humans. This prospective study included 46 patients who underwent liver biopsy. Liver thermal imaging was performed on the same day as liver biopsy. We developed an image-processing algorithm that measured the relative spatial thermal variation across the skin covering the liver. The texture parameters obtained from the thermal images were input into the machine learning algorithm. Patients were diagnosed with MASLD and stratified according to nonalcoholic fatty liver disease activity score (NAS) and fibrosis stage using the METAVIR score. Twenty-one of 46 patients were diagnosed with MASLD. Using thermal imaging followed by processing, detection accuracy for patients with NAS >4 was 0.72.

Resuscitation with aged blood exacerbates liver injury in a hemorrhagic rat model.

OBJECTIVE: Blood loss and transfusion are frequent among patients undergoing liver surgery. Concerns have been raised about the safety and efficacy of transfusing stored blood. The influence of transfusing fresh vs. stored blood on the liver has not been studied to date. We tested the hypothesis that transfusion of stored, but not fresh blood, adversely affects liver outcome in vivo following acute hemorrhage. Additionally, possible mechanisms linking adverse liver outcome with increased storage duration were evaluated. DESIGN: Prospective, controlled, animal study. SETTING: University research laboratory. SUBJECTS: Adult male Sprague-Dawley rats INTERVENTIONS: Anesthetized rats were randomized to control, hemorrhagic and shock group (acute bleeding; HSG), or hemorrhagic and blood resuscitation groups (BR) (with fresh blood [BR-d0], blood stored for 4 [BR-d4] or 7 [BR-d7] days, or packed RBCs stored for 7 days [packed RBC-d7]). MEASUREMENTS AND MAIN RESULTS: Administration of blood or packed RBC stored for 7 days exacerbated liver injury as reflected by liver necrosis and enhanced apoptosis (p < 0.001). Functional MRI analysis of the liver demonstrated significant improvement in liver perfusion with fresh blood (% change in functional MRI signal intensity due to hyperoxia was 16% ± 3% in BR-d0 vs. 4% ± 3% in hemorrhagic group, p < 0.001) but not with stored blood (12% ± 2% and 9% ± 5% for BR-d4 and BR-d7, respectively). Analysis of stored blood showed reduction in RBC deformability at 7 days of storage, reflecting a five-fold increase in the number of undeformable cells. CONCLUSION: Liver injury is exacerbated by the transfusion of stored blood, primarily due to the change in the rheological properties of RBC. This data call for clinical studies in patients undergoing liver resection or transplantation.

Tracing hepatitis B virus to the 16th century in a Korean mummy.

UNLABELLED: A rare find of a mummified child from the 16th century AD, in Korea, with relatively preserved organs, enabled a search for ancient hepatitis B virus (aHBV) DNA sequences from laparoscopic-derived liver biopsies. Analysis of the complete aHBV genome (3,215 base pairs) revealed a unique HBV genotype C2 (HBV/C2) sequence commonly spread in Southeast Asia, which probably represents an HBV that infected the Joseon Dynasty population in Korea. Comparison of the aHBV sequences with contemporary HBV/C2 DNA sequences revealed distinctive differences along four open reading frames. Genetic diversity between contemporary and recovered aHBV/C2 DNA may be the result of immunologic, environmental, and/or pharmacologic pressures. The calculated time of most recent common ancestor suggests that the Korean HBV sequence origin dates back at least 3,000 years and possibly as long as 100,000 years. This isolate most likely represents the earliest human HBV sequence that colonized Southeast Asia by human migration. CONCLUSION: This study describes the complete sequence of the oldest HBV isolate and the most ancient full viral genome known so far.

Continuous 13C-methacetin breath test differentiates biliary atresia from other causes of neonatal cholestasis.

BACKGROUND AND AIM: Distinguishing biliary atresia (BA) from other causes of neonatal cholestasis (NC) is challenging. Continuous BreathID C-methacetin breath test (MBT) is a novel method that determines liver function. Methacetin is metabolized uniquely by the liver and CO2 is measured passively, through a nasal cannula in the exhaled breath. The aim of this study was to assess the ability of MBT to differentiate BA from other causes of NC. METHODS: MBT was performed in infants with NC before any invasive procedure. Percent dose recovered (PDR) peak and time to peak (TTPP) of C recovered were correlated with blood test results and degree of fibrosis on liver biopsy. RESULTS: Fifteen infants were enrolled in the study. Eight were eventually diagnosed as having BA. MBT showed that infants with NC from various causes reached the PDR peak after 44.5 ± 6.7 minutes, whereas infants with BA reached the PDR peak value after 54.7 ± 4.3 minutes (P < 0.005). This suggested low cytochrome P450 1A2 activity in the BA group. The area under the curve (AUC) was 0.95 (95% confidence interval [CI] 0.83-1), sensitivity of 88%, and specificity of 100%. CONCLUSIONS: This pilot study shows that MBT can differentiate between BA and other causes of NC by time to peak of methacetin metabolism. The results suggest that MBT may be used as part of the diagnostic algorithm in infants with liver disease. Larger-scale studies should be conducted to confirm these initial observations.

Accelerated carcinogenesis following liver regeneration is associated with chronic inflammation-induced double-strand DNA breaks.

Hepatocellular carcinoma (HCC) is the third leading cause of cancer mortality worldwide and is considered to be the outcome of chronic liver inflammation. Currently, the main treatment for HCC is surgical resection. However, survival rates are suboptimal partially because of tumor recurrence in the remaining liver. Our aim was to understand the molecular mechanisms linking liver regeneration under chronic inflammation to hepatic tumorigenesis. Mdr2-KO mice, a model of inflammation-associated cancer, underwent partial hepatectomy (PHx), which led to enhanced hepatocarcinogenesis. Moreover, liver regeneration in these mice was severely attenuated. We demonstrate the activation of the DNA damage-response machinery and increased genomic instability during early liver inflammatory stages resulting in hepatocyte apoptosis, cell-cycle arrest, and senescence and suggest their involvement in tumor growth acceleration subsequent to PHx. We propose that under the regenerative proliferative stress induced by liver resection, the genomic unstable hepatocytes generated during chronic inflammation escape senescence and apoptosis and reenter the cell cycle, triggering the enhanced tumorigenesis. Thus, we clarify the immediate and long-term contributions of the DNA damage response to HCC development and recurrence.

Acute infantile liver failure due to mutations in the TRMU gene.

Acute liver failure in infancy accompanied by lactic acidemia was previously shown to result from mtDNA depletion. We report on 13 unrelated infants who presented with acute liver failure and lactic acidemia with normal mtDNA content. Four died during the acute episodes, and the survivors never had a recurrence. The longest follow-up period was 14 years. Using homozygosity mapping, we identified mutations in the TRMU gene, which encodes a mitochondria-specific tRNA-modifying enzyme, tRNA 5-methylaminomethyl-2-thiouridylate methyltransferase. Accordingly, the 2-thiouridylation levels of the mitochondrial tRNAs were markedly reduced. Given that sulfur is a TRMU substrate and its availability is limited during the neonatal period, we propose that there is a window of time whereby patients with TRMU mutations are at increased risk of developing liver failure.

Ischemia and reperfusion liver injury is reduced in the absence of Toll-like receptor 4.

BACKGROUND/AIMS: Toll-like receptor 4 (TLR4) is expressed on hepatic non-parenchymal cells and hepatocytes. Hepatic signaling through TLR4 is critical in the pathogenesis of ischemia reperfusion injury (IRI) and leads to the release of cytokines. The role of bone marrow-derived TLR4 in the early reperfusion stage is unclear. METHODS: We used wild type mice (WT), TLR4deficient (TLR4ko) mice and chimeras to dissociate between the role of TLR4 expression in the liver (TLR4ko/WT) and in the immuno-hematopoietic system (WT/TLR4ko) in mouse hepatic IR injury model. Mice were subjected to in vivo partial IRI (70% for 60 min). RESULTS: Compared with WT IR livers, TLR4ko IRI mice (4 hours) showed a significant reduction in serum liver enzyme, hepatic TNF-α and interleukin-1ß levels. Fewer apoptotic hepatocytes cells were identified by morphological criteria and immunohistochemistry for caspase-3. In TLR4ko mice, decreased hepatic CJUN and NF-ĸB expression during IRI was noted compared with WT mice. Chimeric mice having either TLR4 bone-marrow or non-bone marrow derived cells following IRI exhibited almost similar hepatic injury as WT mice in the immediate reperfusion stage. CONCLUSION: Both TLR4 bone marrow-derived and non-bone marrow-derived cells are necessary in the initial process of hepatic injury. Activating TLR4-dependent signaling is required for IRI. The absence of the TLR4 gene plays a pivotal role in reducing hepatic IR injury.