[Show abstract][Hide abstract] ABSTRACT: Background:
Macrophages play critical roles in liver regeneration, fibrosis development and resolution. They are among the first responders to liver injury and are implicated in orchestrating the fibrogenic response via multiple mechanisms. Macrophages are also intimately associated with the activated hepatic progenitor cell (HPC) niche or ductular reaction that develops in parallel with fibrosis. Among the many macrophage-derived mediators implicated in liver disease progression, a key role for macrophage-derived Wnt proteins in driving pro-regenerative HPC activation towards a hepatocellular fate has been suggested. Wnt proteins, in general, however, have been associated with both pro- and anti-fibrogenic activities in the liver and other organs. We investigated the role of macrophage-derived Wnt proteins in fibrogenesis and HPC activation in murine models of chronic liver disease by conditionally deleting Wntless expression, which encodes a chaperone essential for Wnt protein secretion, in LysM-Cre-expressing myeloid cells (LysM-Wls mice).
Fibrosis and HPC activation were exacerbated in LysM-Wls mice compared to littermate controls, in the absence of an apparent increase in myofibroblast activation or interstitial collagen mRNA expression, in both the TAA and CDE models of chronic liver disease. Increased Epcam mRNA levels paralleled the increased HPC activation and more mature ductular reactions, in LysM-Wls mice. Increased Epcam expression in LysM-Wls HPC was also observed, consistent with a more cholangiocytic phenotype. No differences in the mRNA expression levels of key pro-inflammatory and pro-fibrotic cytokines or the macrophage-derived HPC mitogen, Tweak, were observed. LysM-Wls mice exhibited increased expression of Timp1, encoding the key Mmp inhibitor Timp1 that blocks interstitial collagen degradation, and, in the TAA model, reduced expression of the anti-fibrotic matrix metalloproteinases, Mmp12 and Mmp13, suggesting a role for macrophage-derived Wnt proteins in restraining fibrogenesis during ongoing liver injury.
In summary, these data suggest that macrophage-derived Wnt proteins possess anti-fibrogenic potential in chronic liver disease, which may be able to be manipulated for therapeutic benefit.
[Show abstract][Hide abstract] ABSTRACT: Objective:
Sessile serrated adenomas (SSAs) are the precursors of at least 15% of colorectal carcinomas, but their biology is incompletely understood. We performed a clinicopathological and molecular analysis of a large number of the rarely observed SSAs with dysplasia/carcinoma to better define their features and the pathways by which they progress to carcinoma.
A cross-sectional analysis of 137 SSAs containing regions of dysplasia/carcinoma prospectively collected at a community GI pathology practice was conducted. Samples were examined for BRAF and KRAS mutations, the CpG island methylator phenotype (CIMP) and immunostained for MLH1, p53, p16, β-catenin and 0-6-methylguanine DNA methyltransferase (MGMT).
The median polyp size was 9 mm and 86.5% were proximal. Most were BRAF mutated (92.7%) and 94.0% showed CIMP. Mismatch repair deficiency, evidenced by loss of MLH1 (74.5%) is associated with older age (76.7 versus 71.0; p<0.0029), female gender (70% versus 36%; p<0.0008), proximal location (91% versus 72%; p<0.02), CIMP (98% versus 80%; p<0.02) and lack of aberrant p53 (7% versus 34%; p<0.001) when compared with the mismatch repair-proficient cases. Loss of p16 (43.1%) and gain of nuclear β-catenin (55.5%) were common in areas of dysplasia/cancer, irrespective of mismatch repair status.
SSAs containing dysplasia/carcinoma are predominantly small (<10 mm) and proximal. The mismatch repair status separates these lesions into distinct clinicopathological subgroups, although WNT activation and p16 silencing are common to both. Cases with dysplasia occur at a similar age to cases with carcinoma. This, together with the rarity of these 'caught in the act' lesions, suggests a rapid transition to malignancy following a long dwell time as an SSA without dysplasia.
Gut 10/2015; DOI:10.1136/gutjnl-2015-310456 · 14.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Most colorectal polyps are readily classified, but a subset of tubulovillous adenomas (TVA) with prominent serrated architecture cause diagnostic confusion. We aimed to 1) identify histological features that separate serrated TVAs from both conventional TVAs and traditional serrated adenomas (TSA) and 2) perform a clinicopathological and molecular analysis to determine if the serrated TVA has unique features.
We collected 48 serrated TVAs, 50 conventional TVAs and 66 BRAF wild-type TSAs for analysis. For each polyp we performed a clinicopathological assessment, BRAF and KRAS mutation profiling, CpG island methylator phenotype status, MGMT methylation and immunohistochemical assessment of seven markers (MLH1, p16, p53, β-catenin, Ki67, CK7 and CK20).
We found that serrated TVAs can be reliably diagnosed and have features distinct from both conventional TVAs and TSAs. Compared to conventional TVAs, serrated TVAs are larger, more often proximal, more histologically advanced, show more CpG island methylation and more frequent KRAS mutation. Compared to TSAs, they are more often proximal, show less CpG island methylation, more frequent MGMT methylation and more frequent nuclear staining for β-catenin.
The serrated TVA can be reliably diagnosed and has unique features. It represents a precursor of KRAS mutated, microsatellite stable colorectal carcinoma. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: Current tools for risk stratification of chronic liver disease subjects are limited. We aimed to determine whether the serum-based ELF (Enhanced Liver Fibrosis) test predicted liver-related clinical outcomes, or progression to advanced liver disease, and to compare the performance of ELF to liver biopsy and non-invasive algorithms.
300 patients with ELF scores assayed at the time of liver biopsy were followed up (median 6.1 years) for liver-related clinical outcomes (n=16) and evidence of progression to advanced fibrosis (n=18), by review of medical records and clinical data.
Fourteen of 73 (19.2%) patients with ELF score indicative of advanced fibrosis (≥9.8, the manufacturer's cut-off) had a liver-related clinical outcome, compared to only 2 of 227 (<1%) patients with ELF score <9.8. By contrast, the simple scores APRI and FIB-4 would only have predicted subsequent decompensation in 6 and 4 patients, respectively. A unit increase in ELF score was associated with a 2.53-fold increased risk of a liver-related event (adjusted for age and stage of fibrosis). In patients without advanced fibrosis on biopsy at recruitment, 61% (11/18) with an ELF score ≥9.8 showed evidence of progression to advanced fibrosis (after an average 6 years), whereas only 13.5% of those with an ELF score <9.8 (28/207) progressed (average 14 years). In these subjects, a unit increase in ELF score was associated with a 4.34-fold increased risk of progression. Conclusions The ELF score is a valuable tool for risk stratification of patients with chronic liver disease. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
Liver international: official journal of the International Association for the Study of the Liver 06/2015; DOI:10.1111/liv.12896 · 4.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hepatocyte clone size was measured in liver samples of 21 patients in various stages of chronic hepatitis B virus (HBV) infection and from 21 to 76 years of age. Hepatocyte clones containing unique virus–cell DNA junctions formed by the integration of HBV DNA were detected using inverse nested PCR. The maximum hepatocyte clone size tended to increase with age, although there was considerable patient-to-patient variation in each age group. There was an upward trend in maximum clone size with increasing fibrosis, inflammatory activity and with seroconversion from HBV e-antigen (HBeAg)-positive to HBeAg-negative, but these differences did not reach statistical significance. Maximum hepatocyte clone size did not differ between patients with and without a coexisting hepatocellular carcinoma. Thus, large hepatocyte clones containing integrated HBV DNA were detected during all stages of chronic HBV infection. Using laser microdissection, no significant difference in clone size was observed between foci of HBV surface antigen (HBsAg)-positive and HBsAg-negative hepatocytes, suggesting that expression of HBsAg is not a significant factor in clonal expansion. Laser microdissection also revealed that hepatocytes with normal-appearing histology make up a major fraction of the cells undergoing clonal expansion. Thus, preneoplasia does not appear to be a factor in the clonal expansion detected in our assays. Computer simulations suggest that the large hepatocyte clones are not produced by random hepatocyte turnover but have an as-yet-unknown selective advantage that drives increased clonal expansion in the HBV-infected liver.
[Show abstract][Hide abstract] ABSTRACT: Barrett's esophagus (BE), a common condition, is the only known precursor to esophageal adenocarcinoma (EAC). There is uncertainty about the best way to manage BE, since most people with BE never develop EAC and most patients diagnosed with EAC have no preceding diagnosis of BE. Moreover, there have been recent advances in knowledge and practice about the management of BE and early EAC. To aid clinical decision-making in this rapidly moving field, Cancer Council Australia convened an expert working party to identify pertinent clinical questions. The questions covered a wide range of topics including endoscopic and histologic definitions of BE and early EAC; prevalence, incidence, natural history and risk factors for BE; and methods for managing BE and early EAC. The latter considered modification of lifestyle factors; screening and surveillance strategies; and medical, endoscopic and surgical interventions. To answer each question, the working party systematically reviewed the literature and developed a set of recommendations through consensus. Evidence underpinning each recommendation was rated according to quality and applicability.
This article is protected by copyright. All rights reserved.
Journal of Gastroenterology and Hepatology 01/2015; 30(5). DOI:10.1111/jgh.12913 · 3.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To develop a model of stress-induced senescence to study the hepatocyte senescence associated secretory phenotype (SASP).
Hydrogen peroxide treatment was used to induce senescence in the human HepG2 hepatocyte cell line. Senescence was confirmed by cytochemical staining for a panel of markers including Ki67, p21, heterochromatin protein 1β, and senescence-associated-β-galactosidase activity. Senescent hepatocytes were characterised by gene expression arrays and quantitative polymerase chain reaction (qPCR), and conditioned media was used in proteomic analyses, a human chemokine protein array, and cell migration assays to characterise the composition and function of the hepatocyte SASP.
Senescent hepatocytes induced classical markers of senescence (p21, heterochromatin protein 1β, and senescence-associated-β-galactosidase activity); and downregulated the proliferation marker, Ki67. Hepatocyte senescence induced a 4.6-fold increase in total secreted protein (P = 0.06) without major alterations in the protein profile. Senescence-induced genes were identified by microarray (Benjamini Hochberg-corrected P < 0.05); and, consistent with the increase in secreted protein, gene ontology analysis revealed a significant enrichment of secreted proteins among inducible genes. The hepatocyte SASP included characteristic factors such as interleukin (IL)-8 and IL-6, as well as novel components such as SAA4, IL-32 and Fibrinogen, which were validated by qPCR and/or chemokine protein array. Senescent hepatocyte-conditioned medium elicited migration of inflammatory (granulocyte-macrophage colony stimulating factor, GM-CSF-derived), but not non-inflammatory (CSF-1-derived) human macrophages (P = 0.022), which could contribute to a pro-inflammatory microenvironment in vivo, or facilitate the clearance of senescent cells.
Our novel model of hepatocyte senescence provides insights into mechanisms by which senescent hepatocytes may promote chronic liver disease pathogenesis.
[Show abstract][Hide abstract] ABSTRACT: Background and AimsThere is increasing need to identify individuals with advanced liver fibrosis, who are at risk of complications such as hepatocellular carcinoma. The commercially available Enhanced Liver Fibrosis (ELF) test provides a non-invasive assessment of fibrosis severity. This study was designed to determine the diagnostic accuracy of the manufacturer's cut-off value (≥9.8) in identifying advanced fibrosis.Methods
The relationship between ELF score and fibrosis was examined using serum collected at time of liver biopsy for investigation of liver disease, particularly viral hepatitis. Fibrosis was staged using a modified METAVIR score. If available, liver tissue was recut and stained with Sirius red to determine collagen proportional area and subsinusoidal fibrosis.ResultsELF score ≥9.8 had a sensitivity of 74.4% and specificity 92.4% for detecting advanced fibrosis. In the whole cohort (n=329), ELF score was more likely to incorrectly classify individuals if age was ≥45 years and METAVIR inflammatory grade was 2 or 3 (adjusted OR 3.71 and 2.62 respectively). In contrast, ELF score was less likely to misclassify individuals in the presence of steatosis (OR 0.37). Neither subsinusoidal fibrosis nor collagen proportional area explained the discordance in ELF score for patients with or without advanced fibrosis.Conclusion
Although ELF score ≥9.8 reliably identifies advanced fibrosis in patients with chronic liver disease, both age and inflammatory activity need to be considered when interpreting the result. Importantly, ELF score performed well in the presence of steatosis and could thus be helpful in the assessment of fatty liver disease.This article is protected by copyright. All rights reserved.
Liver international: official journal of the International Association for the Study of the Liver 12/2014; 35(6). DOI:10.1111/liv.12760 · 4.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The traditional serrated adenoma is the least common colorectal serrated polyp. The clinicopathological features and molecular drivers of these polyps require further investigation. We have prospectively collected a cohort of 200 ordinary and advanced traditional serrated adenomas and performed BRAF and KRAS mutational profiling, CpG island methylator phenotype analysis, and immunohistochemistry for a panel of 7 antibodies (MLH1, β-catenin, p53, p16, Ki67, CK7, and CK20) on all cases. The mean age of the patients was 64 years and 50% were female. Of the polyps, 71% were distal. Advanced histology (overt dysplasia or carcinoma) was present in 19% of cases. BRAF mutation was present in 67% and KRAS mutation in 22%. BRAF mutant traditional serrated adenomas were more frequently proximal (39% versus 2%; P≤0.0001), were exclusively associated with a precursor polyp (57% versus 0%; P≤0.0001), and were more frequently CpG island methylator phenotype high (60% versus 16%; P≤0.0001) than KRAS mutant traditional serrated adenomas. Advanced traditional serrated adenomas retained MLH1 expression in 97%, showed strong p53 staining in 55%, and nuclear β-catenin staining in 40%. P16 staining was lost in the advanced areas of 55% of BRAF mutant traditional serrated adenomas compared with 10% of the advanced areas of KRAS mutant or BRAF/KRAS wild-type traditional serrated adenomas. BRAF and KRAS mutant traditional serrated adenomas are morphologically related but biologically disparate polyps with distinctive clinicopathological and molecular features. The overwhelming majority of traditional serrated adenomas retain mismatch repair enzyme function indicating a microsatellite-stable phenotype. Malignant progression occurs via TP53 mutation and Wnt pathway activation regardless of mutation status. However, CDKN2A (encoding the p16 protein) is silenced nearly exclusively in the advanced areas of the BRAF mutant traditional serrated adenomas. Thus, the BRAF mutant traditional serrated adenoma represents an important precursor of the aggressive BRAF mutant, microsatellite-stable subtype of colorectal carcinoma.Modern Pathology advance online publication, 12 September 2014; doi:10.1038/modpathol.2014.122.
Modern Pathology 09/2014; 28(3). DOI:10.1038/modpathol.2014.122 · 6.19 Impact Factor