Nonalcoholic fatty liver disease (NAFLD) is recognized as the leading cause of chronic liver disease in adults and children. NAFLD encompasses a spectrum of liver injuries ranging from steatosis to ...steatohepatitis with or without fibrosis. Fibrosis may progress to cirrhosis and complications including hepatocellular carcinoma. Histologic findings represent the complexity of pathophysiology. NAFLD is closely associated with obesity and is most closely linked with insulin resistance; the current Western diet, high in saturated fats and fructose, plays a significant role. There are several mechanisms by which excess triglycerides are acquired and accumulate in hepatocytes. Formation of steatotic droplets may be disordered in NAFLD. Visceral adipose tissue dysfunction in obesity and insulin resistance results in aberrant cytokine expression; many cytokines have a role in liver injury in NAFLD. Cellular stress and immune reactions, as well as the endocannabinoid system, have been implicated in animal models and in some human studies.
Nonalcoholic fatty liver disease (NAFLD) comprises a spectrum of clinical and histopathological changes including "simple" steatosis, steatosis with inflammation, steatohepatitis, cirrhosis, and ...hepatocellular carcinoma. It was initially described in the context of drug-induced liver injury and acute liver disease following jejunoileal bypass surgery, but since the early 1980s it has been widely acknowledged as the hepatic manifestation of metabolic syndrome. It now represents a burgeoning public health crisis and is fast becoming the main indication for liver transplantation in some parts of the world. Its true incidence and prevalence are unknown, although estimates have been made from large imaging studies. Liver biopsy interpretation is still regarded as the gold standard for making accurate diagnoses in NAFLD, but sampling limitations are recognized. Furthermore, clear definitions for key histopathological components have been lacking, resulting in significant interobserver variations in making a diagnosis of steatohepatitis. In this review the authors consider some aspects of classification and variant forms of NAFLD such as that occurring in children. They provide an update on grading and staging systems and histopathological prognostic factors, and address the role of liver biopsy in contemporary clinical care of patients with NAFLD.
Histological analysis of liver biopsies remains a standard against which other methods of assessment for the presence and amount of hepatic injury due to nonalcoholic fatty liver disease (NAFLD) are ...measured. Histological evaluation remains the sole method of distinguishing steatosis from advanced forms of NAFLD, i.e. nonalcoholic steatohepatitis (NASH) and fibrosis. Included in the lesions of NAFLD are steatosis, lobular and portal inflammation, hepatocyte injury in the forms of ballooning and apoptosis, and fibrosis. However, patterns of these lesions are as distinguishing as the lesions themselves. Liver injury in adults and children due to NAFLD may have different histological patterns. In this review, the rationale for liver biopsy, as well as the histopathological lesions, the microscopically observable patterns of injury, and the differential diagnoses of NAFLD and NASH are discussed.
Histologically assessed hepatocyte ballooning is a key feature discriminating non-alcoholic steatohepatitis (NASH) from steatosis (NAFL). Reliable identification underpins patient inclusion in ...clinical trials and serves as a key regulatory-approved surrogate endpoint for drug efficacy. High inter/intra-observer variation in ballooning measured using the NASH CRN semi-quantitative score has been reported yet no actionable solutions have been proposed.
A focused evaluation of hepatocyte ballooning recognition was conducted. Digitized slides were evaluated by 9 internationally recognized expert liver pathologists on 2 separate occasions: each pathologist independently marked every ballooned hepatocyte and later provided an overall non-NASH NAFL/NASH assessment. Interobserver variation was assessed and a ‘concordance atlas’ of ballooned hepatocytes generated to train second harmonic generation/two-photon excitation fluorescence imaging-based artificial intelligence (AI).
The Fleiss kappa statistic for overall interobserver agreement for presence/absence of ballooning was 0.197 (95% CI 0.094–0.300), rising to 0.362 (0.258–0.465) with a ≥5-cell threshold. However, the intraclass correlation coefficient for consistency was higher (0.718 0.511–0.900), indicating ‘moderate’ agreement on ballooning burden. 133 ballooned cells were identified using a ≥5/9 majority to train AI ballooning detection (AI-pathologist pairwise concordance 19–42%, comparable to inter-pathologist pairwise concordance of between 8–75%). AI quantified change in ballooned cell burden in response to therapy in a separate slide set.
The substantial divergence in hepatocyte ballooning identified amongst expert hepatopathologists suggests that ballooning is a spectrum, too subjective for its presence or complete absence to be unequivocally determined as a trial endpoint. A concordance atlas may be used to train AI assistive technologies to reproducibly quantify ballooned hepatocytes that standardize assessment of therapeutic efficacy. This atlas serves as a reference standard for ongoing work to refine how ballooning is classified by both pathologists and AI.
For the first time, we show that, even amongst expert hepatopathologists, there is poor agreement regarding the number of ballooned hepatocytes seen on the same digitized histology images. This has important implications as the presence of ballooning is needed to establish the diagnosis of non-alcoholic steatohepatitis (NASH), and its unequivocal absence is one of the key requirements to show ‘NASH resolution’ to support drug efficacy in clinical trials. Artificial intelligence-based approaches may provide a more reliable way to assess the range of injury recorded as “hepatocyte ballooning”.
Display omitted
•Hepatocyte ballooning identification underpins regulatory-approved drug efficacy endpoints in clinical trials.•We report substantial variation in ballooned cell identification by expert hepatopathologists.•Our data suggest that ballooning is too subjective for its presence or complete absence to be used as a trial endpoint.•A ‘concordance atlas’ of cells identified as ballooned by multiple pathologists can be used to train AI-based image analysis.•AI-based approaches may provide a more reliable way to assess the range of injury recorded as hepatocyte ballooning.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
E2F family of transcription factors regulates various cellular functions related to cell cycle and apoptosis. Its individual members have traditionally been classified into activators and repressors, ...based on in vitro studies. However their contribution in human cancer is more complicated and difficult to predict. We review current knowledge on the expression of E2Fs in digestive system malignancies and its clinical implications for patient prognosis and treatment. E2F1, the most extensively studied member and the only one with prognostic value, exhibits a tumor-suppressing activity in esophageal, gastric and colorectal adenocarcinoma, and in hepatocellular carcinoma (HCC), whereas in pancreatic ductal adenocarcinoma and esophageal squamous cell carcinoma may function as a tumor-promoter. In the latter malignancies, E2F1 immunohistochemical expression has been correlated with higher tumor grade and worse patient survival, whereas in esophageal, gastric and colorectal adenocarcinomas is a marker of increased patient survival. E2F2 has only been studied in colorectal cancer, where its role is not considered significant. E2F4's role in colorectal, gastric and hepatic carcinogenesis is tumor-promoting. E2F8 is strongly upregulated in human HCC, thus possibly contributing to hepatocarcinogenesis. Adenoviral transfer of E2F as gene therapy to sensitize pancreatic cancer cells for chemotherapeutic agents has been used in experimental studies. Other therapeutic strategies are yet to be developed, but it appears that targeted approaches using E2F-agonists or antagonists should take into account the tissue-dependent function of each E2F member. Further understanding of E2Fs' contribution in cellular functions in vivo would help clarify their role in carcinogenesis.
The diagnosis of autoimmune hepatitis (AIH) is based on a combination of biochemical, immunological and histological features and exclusion of other causes of liver disease. Typical histological ...features include a chronic hepatitis pattern of injury with portal inflammation and interface activity, predominance of plasma cells in the portal infiltrate, emperipolesis, and hepatocellular rosette formation. Centrilobular injury with prominent hepatocellular necrosis and mononuclear inflammation is now recognised in the histological spectrum of AIH and may represent an early stage of the disease. Liver histology plays a major role in clinical diagnostic scoring systems and is important to confirm or support the clinical diagnosis of AIH. This review focuses on the role of histopathology in AIH and highlights the contribution of histological interpretation to the diagnosis of AIH, differential diagnosis from other entities, recognition of concurrent liver disease, and identification of the so-called overlap or variant syndromes, and addresses the importance of liver biopsy in the management and prognosis of patients with AIH.
Nonalcoholic fatty liver disease (NAFLD) is recognized as the most common cause of chronic liver disease in western countries. NAFLD is etiologically associated with systemic and hepatic insulin ...resistance and is considered by many as the hepatic manifestation of the metabolic syndrome. NAFLD has a wide histological spectrum ranging from ‘simple’ steatosis to nonalcoholic steatohepatitis (NASH), which may progress to cirrhosis. Hepatocellular carcinoma may occur in NASH-related cirrhosis. The diagnosis of NAFLD/NASH is based on clinico-pathological criteria. Currently available noninvasive tests for the diagnosis of NASH lack specificity and sensitivity, so liver biopsy, despite its limitations, still remains the ‘golden standard’ for confirming or excluding NASH in a patient with chronically-elevated liver enzymes and image-detected steatosis. This review examines the currently used criteria for the histopathological diagnosis of NAFLD/NASH in adults and children and the relevant histological scoring systems.
The SALVE Histopathology Group (SHG) developed and validated a grading and staging system for the clinical and full histological spectrum of alcohol-related liver disease (ALD) and evaluated its ...prognostic utility in a multinational cohort of 445 patients.
SALVE grade was described by semiquantitative scores for steatosis, activity (hepatocellular injury and lobular neutrophils) and cholestasis. The histological diagnosis of steatohepatitis due to ALD (histological ASH, hASH) was based on the presence of hepatocellular ballooning and lobular neutrophils. Fibrosis staging was adapted from the Clinical Research Network staging system for non-alcoholic fatty liver disease and the Laennec staging system and reflects the pattern and extent of ALD fibrosis. There are 7 SALVE fibrosis stages (SFS) ranging from no fibrosis to severe cirrhosis.
Interobserver κ-value for each grading and staging parameter was >0.6. In the whole study cohort, long-term outcome was associated with activity grade and cholestasis, as well as cirrhosis with very broad septa (severe cirrhosis) (p <0.001 for all parameters). In decompensated ALD, adverse short-term outcome was associated with activity grade, hASH and cholestasis (p = 0.038, 0.012 and 0.001, respectively), whereas in compensated ALD, hASH and severe fibrosis/cirrhosis were associated with decompensation-free survival (p = 0.011 and 0.001, respectively). On multivariable analysis, severe cirrhosis emerged as an independent histological predictor of long-term survival in the whole study cohort. Severe cirrhosis and hASH were identified as independent predictors of short-term survival in decompensated ALD, and also as independent predictors of decompensation-free survival in compensated ALD.
The SALVE grading and staging system is a reproducible and prognostically relevant method for the histological assessment of disease activity and fibrosis in ALD.
Patients with alcohol-related liver disease (ALD) may undergo liver biopsy to assess disease severity. We developed a system to classify ALD under the microscope by grading ALD activity and staging the extent of liver scarring. We validated the prognostic performance of this system in 445 patients from 4 European centers.
Display omitted
•ALD is the most frequent cause of cirrhosis in Europe, but an ALD-specific histologic grading and staging system is lacking.•The SALVE Histopathology Group developed a reproducible grading and staging system for ALD.•Prognostic value of the new grading and staging system was evaluated in a large cohort of patients with ALD enrolled at 4 European centers.•ASH and severe cirrhosis on histology were independent predictors of liver-related events/deaths in compensated/decompensated ALD.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The autonomic nervous system plays a role in a variety of liver regenerative and metabolic functions, including modulating bile secretion and cholangiocyte and hepatobiliary progenitors of the canals ...of Hering. However, the nature and location of nerves which link to the proximal biliary tree have remained uncertain. We investigate the anatomic relationship of nerves to the proximal biliary tree including the putative stem/progenitor cell niche of the canal of Hering. Using double immunostaining (fluorescence, histochemistry) to highlight markers of cholangiocytes (biliary-type keratins), nerves (S100, neurofilament protein, PGP9.5, tyrosine hydroxylase), and stellate cells (CRBP-1), we examined sections from normal adult livers from autopsy or surgical resections. There is extensive contact between nerves and interlobular bile ducts, bile ductules, and canals of Hering (CoH). In multiple serial sections from 4 normal livers, biliary-nerve contacts were seen in all of these structures and were more common in the interlobular bile ducts (78/137; 57%) than in the ductules and CoH (95/294; 33%) (
p
< 0.001). Contacts appear to consist of nerves in juxtaposition to the biliary basement membrane, though crossing through basement membrane to interface directly with cholangiocytes is also present. These nerves are positive for tyrosine hydroxylase and are, thus, predominately adrenergic. Electron microscopy confirms nerves closely approximating ductules. Nerve fiber–hepatic stellate cell juxtaposition is observed but without stellate cell approximation to cholangiocytes. We present novel findings of biliary innervation, perhaps mediated in part, by direct cholangiocyte-nerve interactions. The implications of these findings are protean for studies of neuromodulation of biliary physiology and hepatic stem/progenitor cells.
The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH) is increasing, and translational animal models are ...needed to develop novel treatments for this disease. The physiology and metabolism of pigs have a relatively high resemblance to humans, and the present study aimed to characterise choline-deficient, and high-fat diet (CDAHFD) fed Göttingen Minipigs as a novel animal model of MASLD/MASH. Göttingen Minipigs were fed CDAHFD for up to 5 months, and the phenotype was investigated by analysis of plasma parameters and repeated collection of liver biopsies. Furthermore, changes in hepatic gene expression during the experiment were explored by RNA sequencing. For a subset of the minipigs, the diet was changed from CDAHFD back to chow to investigate if the liver pathology was reversible. Göttingen Minipigs on CDAHFD gained bodyweight, and plasma levels of cholesterol, AST, ALT, ALP and GGT were increased. CDAHFD-fed minipigs developed hepatic steatosis, inflammation, and fibrosis, which in 5 of 16 animals progressed to cirrhosis. During an 11-week chow reversal period, steatosis regressed while fibrosis persisted. Regarding inflammation, the findings were less clear, depending on the type of readout. MASH Human Proximity Scoring (combined evaluation of transcriptional, phenotypic and histopathological parameters) showed that CDAHFD-fed Göttingen Minipigs resemble human MASLD/MASH better than most rodent models. In conclusion, CDAHFD-fed minipigs develop a MASH-like phenotype which in several aspects resemble the changes observed in human patients with MASLD/MASH. Furthermore, repeated collection of liver biopsies allow detailed characterisation of histopathological changes over time in individual animals.
PDF
