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Background: Chronic Hepatitis B virus (HBV) infection can lead to the development of chronic hepatitis, cirrhosis and hepatocellular carcinoma. We hypothesized that HBV might accelerate hepatocyte ageing and investigated the effect of HBV on hepatocyte cell cycle state and biological age. We also investigated the relation between inflammation, fibrosis and cell cycle phase., Methods: Liver samples from patients with chronic HBV (n = 91), normal liver (n = 55) and regenerating liver (n = 15) were studied. Immunohistochemistry for cell cycle phase markers and HBV antigens was used to determine host cell cycle phase. Hepatocyte-specific telomere length was evaluated by quantitative fluorescent in-situ hybridization (Q-FISH) in conjunction with hepatocyte nuclear area and HBV antigen expression. The effects of induced cell cycle arrest and induced cellular senescence on HBV production were assessed in vitro., Results: 13.7% hepatocytes in chronic HBV had entered cell cycle, but expression of markers for S, G2 and M phase was low compared with regenerating liver. Hepatocyte p21 expression was increased (10.9%) in chronic HBV and correlated with liver fibrosis. Mean telomere length was reduced in chronic HBV compared to normal. However, within HBV-affected livers, hepatocytes expressing HBV antigens had longer telomeres. Telomere length declined and hepatocyte nuclear size increased as HBV core antigen (HBcAg) expression shifted from the nucleus to cytoplasm. Nuclear co-expression of HBcAg and p21 was not observed. Cell cycle arrest induced in vitro was associated with increased HBV production, in contrast to in vitro induction of cellular senescence, which had no effect., Conclusion: Chronic HBV infection was associated with hepatocyte G1 cell cycle arrest and accelerated hepatocyte ageing, implying that HBV induced cellular senescence. However, HBV replication was confined to biologically younger hepatocytes. Changes in the cellular location of HBcAg may be related to the onset of cellular senescence.

Insulin resistance has been described in association with chronic liver disease for decades. Hepatocyte senescence has been demonstrated in chronic liver disease and as many as 80% of hepatocytes show a senescent phenotype in advanced liver disease. The aim of this study was to understand the role of hepatocyte senescence in the development of insulin resistance. Senescence was induced in HepG2 cells via oxidative stress. The insulin metabolic pathway was studied in control and senescent cells following insulin stimulation. GLUT2 and GLUT4 expressions were studied in HepG2 cells and human liver tissue. Further, GLUT2 and GLUT4 expressions were studied in three independent chronic liver disease cohorts. Signalling impairment distal to Akt in phosphorylation of AS160 and FoxO1 was evident in senescent HepG2 cells. Persistent nuclear localisation of FoxO1 was demonstrated in senescent cells despite insulin stimulation. Increased GLUT4 and decreased GLUT2 expressions were evident in senescent cells, human cirrhotic liver tissue and publically available liver disease datasets. Changes in GLUT expressions were associated with a poor clinical prognosis. In conclusion, selective insulin resistance is evident in senescent HepG2 cells and changes in GLUT expressions can be used as surrogate markers of hepatocyte senescence., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Hepatocyte senescence is associated closely with fibrosis stage and an adverse outcome in chronic liver disease, but it is uncertain whether there is a causal relation with clinical manifestations of chronic liver disease, which was the subject of this study of the senescent hepatocyte gene signature. Senescence was induced in HepG2 cells using sub-lethal concentrations of H2O2. Gene expression of control and senescent HepG2 cells were studied. Comparison was made with patients with cirrhosis and three public microarray datasets. H2O2-treated HepG2 cells demonstrated characteristic cellular senescence. There was differential expression of 354 genes in senescence. Up-regulated genes in HepG2 senescence were also up regulated in patients with cirrhosis. The senescent hepatocyte gene signature distinguished liver disease from normal by unsupervised clustering in the public chronic liver disease microarray datasets, with enrichment of the senescence gene signature in all three datasets. The senescent hepatocyte gene signature included changes in cell cycle regulation, morphology, inflammation, signal transduction, metabolism and stellate cell activation, which alongside impaired synthetic function in senescence in vitro were consistent with manifestations of clinical liver disease, suggesting a close relation between hepatocyte senescence and manifestations of chronic liver disease including fibrosis and impaired synthetic function., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Background and Aim: Alcohol-related liver disease (ALD) remains a leading cause of liver-related morbidity and mortality. Age, fibrosis stage, MELD score and continued alcohol consumption predict outcome in everyday clinical practice. In previous studies increased hepatocyte nuclear area and hepatocyte expression of p21, both markers of senescence, were associated with increased fibrosis stage and a poor outcome in non-alcohol-related fatty liver disease, while increased hepatocyte nuclear area was related to liver dysfunction in ALD cirrhosis. This study, therefore, investigated the pattern of hepatocyte cell cycle phase distribution and hepatocyte p21 expression in relation to outcome in ALD., Methods: Liver sections from two cohorts were studied. The first comprised 42 patients across the full spectrum of ALD. The second cohort comprised 77 patients with ALD cirrhosis. Immunohistochemistry assessed hepatocyte expression of cell cycle phase markers and p21. Regenerating liver (n=12) and "normal" liver sections (n=5) served as positive and negative controls, respectively., Results: In the first cohort there was little cell cycle progression beyond G1/S phase and increased hepatocyte p21 expression (p<0.0001), which correlated independently with fibrosis stage (p=0.005) and an adverse liver-related outcome (p=0.03). In the second cohort, both hepatocyte p21 expression (p<0.001) and MELD score (p=0.006) were associated independently with an adverse liver-related outcome; this association was stronger with hepatocyte p21 expression (AUROC 0.74; p=0.0002) than with MELD score (AUROC 0.59; p=0.13). Further, hepatocyte p21 expression co-localised with increased hepatic stellate cell activation., Conclusions: The findings are consistent with impaired cell cycle progression beyond the G1/S phase in ALD. The striking independent associations between increased hepatocyte p21 expression and both fibrosis stage and an adverse liver-related outcome in both cohorts suggests hepatocyte senescence plays an important role in ALD. Measuring hepatocyte p21 expression is simple and cheap and in this series was a useful measure of long-term prognosis in ALD.

Unlabelled: Telomeres, a validated biomarker of aging, comprise multiple nucleotide repeats capping chromosomes that shorten with each cell cycle until a critical length is achieved, precipitating cell senescence. Only two previous studies focused on the effect of aging in "normal" liver tissue, but these studies were compromised by small sample size, limited age range, tissue derived from individuals with an increased risk of senescence, and the use of liver homogenates. We developed a robust large-volume, four-color quantitative fluorescent in situ hybridization technique to measure telomere length in large numbers of hepatocytes, Kupffer cells, hepatic stellate cells, CD4-positive and CD8-positive lymphocytes, and cholangiocytes. Following validation against the gold standard (Southern blotting), the technique was applied to normal archived paraffin-embedded liver tissue obtained following reperfusion of implanted donor liver. We studied 73 highly selected donors aged 5-79 years with a short medical illness preceding death and no history of liver disease, reperfusion injury, or steatosis and normal graft function 1-year posttransplantation. Cholangiocytes had significantly longer telomeres compared with all other intrahepatic lineages over a wide age range (P < 0.05). Age-related telomere attrition was restricted to sinusoidal cells (i.e., Kupffer cells [P = 0.0054] and stellate cells [P = 0.0001]). Cholangiocytes and hepatocytes showed no age-related telomere shortening., Conclusion: In normal liver and over a broad age range, cholangiocytes have longer telomeres than all other intrahepatic lineages. Age-related telomere length decline is restricted to Kupffer cells and stellate cells., (Copyright © 2012 American Association for the Study of Liver Diseases.)

Immune senescence is the normal process whereby the human immune system ages, but becomes less effective. We investigated whether liver transplant recipients have features of immune senescence. Lymphocytes from 97 liver transplant recipients with established grafts and 41 age-matched and sex-matched controls were subjected to an 8-color flow cytometry assay that measured expression of killer cell lectin-like receptor subfamily G member 1, cluster of differentiation 127 (CD127), CD45RO, CD27, CD28, CD4, CD8, and CD57. Lymphocyte telomere length was assessed by flow-fluorescence in situ hybridization. Cases were compared with controls for each marker of immune senescence using a Mann-Whitney U test. For liver transplant recipients, linear regression analyses identified associations between markers of immune senescence and clinical or demographic characteristics. Lymphocytes from liver transplant recipients expressed more phenotypic markers of maturity than did lymphocytes from controls. Lymphocyte telomeres were shorter in liver transplant recipients than in controls. Age, hepatocellular carcinoma at transplantation, and skin malignancy developing after transplantation were associated independently with shortened lymphocyte telomeres. Increasing age and previous cytomegalovirus infection were associated independently with phenotypic markers of lymphocyte maturity. Thus, lymphocytes from liver transplant recipients are older "biologically" than lymphocytes from age-matched and sex-matched controls. Hepatocellular carcinoma at transplantation, subsequent skin malignancy, and previous cytomegalovirus infection are associated with lymphocyte senescence in liver transplant recipients., (2010 AASLD.)