Non‐alcoholic fatty liver disease – histological scoring systems: a large cohort single‐center,evaluation study

Non‐alcoholic fatty liver disease (NAFLD) is an increasingly common cause of chronic liver disease. Till date, liver biopsy remains the gold standard for identification and quantification of the wide histological spectra of NAFLD. Histological scorings are very useful and widely applied for the diagnosis and management in clinical trials and follow‐up studies of non‐alcoholic steatohepatitis (NASH). However, in view of scarce published literature, there is a need to evaluate them in large cohort of NAFLD. This study was aimed to evaluate the two histological scoring systems (NAS‐CRN, SAF) in the diagnosis of NAFLD and to assess the role of histological characteristics as injury markers in NAFLD. Retrospective histological study of liver biopsies of 1000 patients diagnosed as NAFLD, between 2010 and 2016, was conducted. Histopathologic evaluation and semiquantiative scoring based on NAS‐CRN and SAF algorithm and their correlation with serum aminotransferase and fibrosis were performed. Liver biopsies were classified according to the NAS‐CRN scoring, as NAS <3 (not NASH) in 72 (7.2%), NAS 3–4 (borderline NASH) in 310 (31%), and NAS ≥5 (definite NASH) in 618 (61.8%), and SAF classified 117 (11.7%) not NASH and 883 (88.3%) definite NASH. There was excellent concordance for definite NASH and not NASH; however, 88.06% of borderline NASH was classified as NASH by SAF. 76.39% by NAS and 78.63% by SAF algorithm who were diagnosed as not NASH showed the presence of fibrosis; however, higher stages of fibrosis were significantly more prevalent in definite NASH, excluding burnt‐out cirrhosis. Serum ALT was significantly associated with increasing stages of fibrosis (p < 0.001) and the three categories (not NASH, borderline NASH, and definite NASH) when classified as with/without fibrosis (p < 0.001). Steatosis of higher grades, more ballooned cells, and more foci of Lobular Inflammation were found in significantly higher proportion of patients with NASH (p < 0.001), with higher fibrosis stages (p < 0.001) and higher serum ALT levels (p < 0.001). NAFLD classifications based on histological scoring NAS‐CRN and SAF algorithm are concordant for the category of definite NASH and not NASH, while borderline NASH shows discrepant interpretation. There was highly significant correlation between the NAS and SAF categories with high grades of histological characteristics, with serum ALT and with higher stages of fibrosis. Exclusion of fibrosis is a limitation with both scores.     

Noninvasive predictors of nonalcoholic steatohepatitis in Korean patients with histologically proven nonalcoholic fatty liver disease

Background/Aims

The aims of this study were (1) to identify the useful clinical parameters of noninvasive approach for distinguishing nonalcoholic steatohepatitis (NASH) from nonalcoholic fatty liver disease (NAFLD), and (2) to determine whether the levels of the identified parameters are correlated with the severity of liver injury in patients with NASH.

Methods

One hundred and eight consecutive patients with biopsy-proven NAFLD (age, 39.8±13.5 years, mean±SD; males, 67.6%) were prospectively enrolled from 10 participating centers across Korea.

Results

According to the original criteria for NAFLD subtypes, 67 patients (62.0%) had NASH (defined as steatosis with hepatocellular ballooning and/or Mallory-Denk bodies or fibrosis ≥2). Among those with NAFLD subtype 3 or 4, none had an NAFLD histologic activity score (NAS) below 3 points, 40.3% had a score of 3 or 4 points, and 59.7% had a score >4 points. Fragmented cytokeratin-18 (CK-18) levels were positively correlated with NAS (r=0.401), as well as NAS components such as lobular inflammation (r=0.387) and ballooning (r=0.231). Fragmented CK-18 was also correlated with aspartate aminotransferase (r=0.609), alanine aminotransferase (r=0.588), serum ferritin (r=0.432), and the fibrosis stage (r=0.314). A fragmented CK-18 cutoff level of 235.5 U/L yielded sensitivity, specificity, and positive and negative predictive values of 69.0%, 64.9%, 75.5% (95% CI 62.4-85.1), and 57.1% (95% CI 42.2-70.9), respectively, for the diagnosis of NASH.

Conclusions

Serum fragmented CK-18 levels can be used to distinguish between NASH and NAFL. Further evaluation is required to determine whether the combined measurement of serum CK-18 and ferritin levels improves the diagnostic performance of this distinction.     

Quantifying hepatic steatosis - more than meets the eye

Levene A P, Kudo H, Armstrong M J, Thursz M R, Gedroyc W M, Anstee Q M & Goldin R D
(2012) Histopathology  60, 971–981 Quantifying hepatic steatosis – more than meets the eye Aims: The non‐alcoholic fatty liver disease (NAFLD) activity score (NAS) is the histological tool used to assess disease severity based on steatosis, inflammation and hepatocyte ballooning. As steatosis contributes up to three of a potential eight points to NAS, it is important to quantify steatosis accurately. We sought to determine the optimum histological technique for identifying fat in tissue. Methods and results: Using tissue from a mouse model of NAFLD, with validation in human liver biopsies, the percentage steatosis and fat droplet size were assessed in haematoxylin and eosin (H&E)‐ and Oil Red‐O (ORO)‐stained sections by light microscopy and digital image analysis (DIA). Results were compared to biochemical tissue triglyceride content and MRI assessment of hepatic lipid content. H&E steatosis assessment correlated poorly with tissue triglyceride concentration. However, ORO DIA exhibited much higher sensitivity and specificity for steatosis and correlated very well with triglyceride concentration in mouse and human liver (R = 0.706, P = 0.001 and R = 0.894, P =0.041, respectively). MRI‐based assessment of steatosis was inaccurate. Conclusions: ORO DIA is the most accurate method for detecting and quantifying steatosis. Although H&E‐based NAS remains clinically valid in both clinical research and experimental situations, ORO DIA is a more robust technique to assess liver steatosis accurately for NAS scoring.     

Pathology of the liver in obese and diabetic ob/ob and db/db mice fed a standard or high-calorie diet

Non‐alcoholic fatty liver disease (NAFLD) is one of the commonest liver diseases in Western countries. Although leptin deficient ob/ob and db/db mice are frequently used as murine models of NAFLD, an exhaustive characterization of their hepatic lesions has not been reported to date, particularly under calorie overconsumption. Thus, liver lesions were characterized in 78 ob/ob and db/db mice fed either a standard or high‐calorie (HC) diet, for one or three months. Steatosis, necroinflammation, apoptosis and fibrosis were assessed and the NAFLD activity score (NAS) was calculated. Steatosis was milder in db/db mice compared to ob/ob mice and was more frequently microvesicular. Although necroinflammation was usually mild in both genotypes, it was aggravated in db/db mice after one month of calorie overconsumption. Apoptosis was observed in db/db mice whereas it was only detected in ob/ob mice after HC feeding. Increased apoptosis was frequently associated with microvesicular steatosis. In db/db mice fed the HC diet for three months, fibrosis was aggravated while steatosis, necroinflammation and apoptosis tended to alleviate. This was associated with increased plasma β‐hydroxybutyrate suggesting an adaptive stimulation of hepatic mitochondrial fatty acid oxidation (FAO). Nevertheless, one‐third of these db/db mice had steatohepatitis (NAS ≥ 5), whereas none of the ob/ob mice developed non‐alcoholic steatohepatitis under the same conditions. Steatosis, necroinflammation, apoptosis and fibrosis are modulated by calorie overconsumption in the context of leptin deficiency. Association between apoptosis and microvesicular steatosis in obese mice suggests common mitochondrial abnormalities. Enhanced hepatic FAO in db/db mice is associated with fibrosis aggravation.     

Animal models of non‐alcoholic fatty liver disease: current perspectives and recent advances

Non‐alcoholic fatty liver disease (NAFLD) is a continuous spectrum of diseases characterized by excessive lipid accumulation in hepatocytes. NAFLD progresses from simple liver steatosis to non‐alcoholic steatohepatitis and, in more severe cases, to liver fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Because of its growing worldwide prevalence, various animal models that mirror both the histopathology and the pathophysiology of each stage of human NAFLD have been developed. The selection of appropriate animal models continues to be one of the key questions faced in this field. This review presents a critical analysis of the histopathology and pathogenesis of NAFLD, the most frequently used and recently developed animal models for each stage of NAFLD and NAFLD‐induced HCC, the main mechanisms involved in the experimental pathogenesis of NAFLD in different animal models, and a brief summary of recent therapeutic targets found by the use of animal models. Integrating the data from human disease with those from animal studies indicates that, although current animal models provide critical guidance in understanding specific stages of NAFLD pathogenesis and progression, further research is necessary to develop more accurate models that better mimic the disease spectrum, in order to provide both increased mechanistic understanding and identification/testing of novel therapeutic approaches. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

Hepatocellular carcinoma in a mouse model fed a choline‐deficient,L‐amino acid‐defined,high‐fat diet

Hepatocellular carcinoma (HCC) is a common cancer worldwide and represents the outcome of the natural history of chronic liver disease. The growing rates of HCC may be partially attributable to increased numbers of people with non‐alcoholic fatty liver disease (NAFLD) and non‐alcoholic steatohepatitis (NASH). However, details of the liver‐specific molecular mechanisms responsible for the NAFLD–NASH–HCC progression remain unclear, and mouse models that can be used to explore the exact factors that influence the progression of NAFLD/NASH to the more chronic stages of liver disease and subsequent HCC are not yet fully established. We have previously reported a choline‐deficient, L‐amino acid‐defined, high‐fat diet (CDAHFD) as a dietary NASH model with rapidly progressive liver fibrosis in mice. The current study in C57BL/6J mice fed CDAHFD provided evidence for the chronic persistence of advanced hepatic fibrosis in NASH and disease progression towards HCC in a period of 36 weeks. When mice fed CDAHFD were switched back to a standard diet, hepatic steatosis was normalized and NAFLD activity score improved, but HCC incidence increased and the phenotype of fibrosis‐associated HCC development was observed. Moreover, when mice continued to be fed CDAHFD for 60 weeks, HCC further developed without severe body weight loss or carcinogenesis in other organs. The autochthonous tumours showed a variety of histological features and architectural patterns including trabecular, pseudoglandular and solid growth. The CDAHFD mouse model might be a useful tool for studying the development of HCC from NAFLD/NASH, and potentially useful for better understanding pathological changes during hepatocarcinogenesis.     

Pathologic features associated with fibrosis in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) represents a spectrum of clinicopatholologic conditions ranging from steatosis alone to nonalcoholic steatohepatitis (NASH), with varying risks for progression to cirrhosis. Although steatosis alone seems to be nonprogressive, some patients with NASH can progress. This study focuses on the clinical and pathological characteristics of patients with NAFLD associated with the development of histological fibrosis. Patients with an established diagnosis of nonalcoholic fatty liver were identified through our NAFLD database containing extensive clinical, demographic, and laboratory data. Liver biopsy specimens were read blindly by one hepatopathologist using a 19-item pathological protocol and by another hepatopathologist using a second pathological protocol. Clinical and pathological data were matched to the presence of different types of histological fibrosis. Univariate and multivariate analyses helped determine all of the variables independently associated with histological fibrosis. Of 132 NAFLD patients, 21.2% had advanced fibrosis (septal/bridging fibrosis or well-established cirrhosis). Sinusoidal fibrosis was present in 20.3% of patients, whereas perivenular fibrosis was seen in 17.2%. Ballooning degeneration and Mallory bodies were independently associated with both sinusoidal fibrosis and perivenular fibrosis. Aspartate aminotransferase/alanine aminotransferase ratio and ballooning degeneration were also independently associated with periportal-portal fibrosis. We conclude that the presence of hepatocyte injury in NAFLD is associated with fibrosis. These pathological features can be used to establish the pathological criteria for diagnosis of the progressive form of NAFLD or NASH.     

Mitochondrial genome architecture in non‐alcoholic fatty liver disease

Non‐alcoholic fatty liver disease (NAFLD) is associated with mitochondrial dysfunction, a decreased liver mitochondrial DNA (mtDNA) content, and impaired energy metabolism. To understand the clinical implications of mtDNA diversity in the biology of NAFLD, we applied deep‐coverage whole sequencing of the liver mitochondrial genomes. We used a multistage study design, including a discovery phase, a phenotype‐oriented study to assess the mutational burden in patients with steatohepatitis at different stages of liver fibrosis, and a replication study to validate findings in loci of interest. We also assessed the potential protein‐level impact of the observed mutations. To determine whether the observed changes are tissue‐specific, we compared the liver and the corresponding peripheral blood entire mitochondrial genomes. The nuclear genes POLG and POLG2 (mitochondrial DNA polymerase‐γ) were also sequenced. We observed that the liver mtDNA of patients with NAFLD harbours complex genomes with a significantly higher mutational (1.28‐fold) rate and degree of heteroplasmy than in controls. The analysis of liver mitochondrial genomes of patients with different degrees of fibrosis revealed that the disease severity is associated with an overall 1.4‐fold increase in mutation rate, including mutations in genes of the oxidative phosphorylation (OXPHOS) chain. Significant differences in gene and protein expression patterns were observed in association with the cumulative number of OXPHOS polymorphic sites. We observed a high degree of homology (～98%) between the blood and liver mitochondrial genomes. A missense POLG p.Gln1236His variant was associated with liver mtDNA copy number. In conclusion, we have demonstrated that OXPHOS genes contain the highest number of hotspot positions associated with a more severe phenotype. The variability of the mitochondrial genomes probably originates from a common germline source; hence, it may explain a fraction of the ‘missing heritability’ of NAFLD. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Nuclear size measurement is a simple method for the assessment of hepatocellular aging in non‐alcoholic fatty liver disease: Comparison with telomere‐specific quantitative FISH and p21 immunohistochemistry

Telomere‐specific quantitative fluorescent in situ hybridization (Q‐FISH) accurately evaluates hepatocellular aging on histological sections, but it requires appropriate tissue processing. To establish a more simple method for the assessment of hepatocellular aging, the usefulness of nuclear size measurement was clarified using biopsy liver samples from 64 patients with non‐alcoholic fatty liver disease (NAFLD), a model for oxidative stress‐associated hepatocellular aging, and 11 control individuals. Relative telomere intensity (RTI) was measured on Q‐FISH, and the relative nuclear size (RNS) was calculated as the average nuclear size of the hepatocytes divided by that of lymphocytes. In normal individuals and NAFLD patients, the RTI and RNS were negatively correlated. The degree of nuclear enlargement in NAFLD patients was larger than that in normal individuals with the same telomere length, possibly reflecting telomere‐independent senescence. In NAFLD patients with RNS >2.0, the regenerative responses, indicated by the ratio of Ki‐67‐positive index to serum alanine aminotransferase level, were significantly reduced. The RNS positively correlated with the p21 expression, another marker of senescence. This all indicates that nuclear enlargement progresses in parallel with reduced regenerative responses, telomere shortening, and p21 upregulation. Nuclear size measurement is an effective method for estimation of hepatocellular aging.     

Physiological hepatic nuclear vacuolation—how long does it persist?

Levene A P & Goldin R D
(2010) Histopathology 56 , 426–429 Physiological hepatic nuclear vacuolation—how long does it persist? Aims: Nuclear vacuolation\glycogenation is a characteristic histological feature of non‐alcoholic fatty liver disease (NAFLD) that can help distinguish it from alcohol‐induced liver disease. There are, however, other associations of nuclear vacuolation of which the commonest is as a normal feature of childhood. The aim of this study was to identify how long this physiological nuclear vacuolation persists. Methods and results: Liver biopsy specimens from 872 patients with chronic hepatitis B virus infection (a condition known not to be associated with nuclear vacuolation) were studied to assess the frequency of nuclear vacuolation at different ages. All the patients studied had a body mass index of <25 kg/m² and an alcohol intake of <15 units/week, as well as no other risk factors for liver disease. It was found that the frequency of nuclear vacuolation, in the absence of NAFLD, fell from 13% at age 20–24 years to 4% in the early 30s and to 0% at age 60–64 years. Conclusions: Physiological hepatic nuclear vacuolation is common in the 20s and persists into the 30s. This knowledge can help in the assessment of liver biopsy specimens in which nuclear vacuolation is a feature.     

Serum lipocalin-2 is a potential biomarker for the clinical diagnosis of nonalcoholic steatohepatitis

Background/AimsNonalcoholic steatohepatitis (NASH) is a progressive form of nonalcoholic fatty liver disease (NAFLD) characterized by hepatic steatosis, inflammation, hepatocellular injury, and fibrosis. We aimed to investigate the usefulness of a key biomarker, lipocalin-2 (LCN2), for the detection of NASH progression.MethodsA mouse NASH model was established using a high-fat diet and a high-sugar drinking water. Gene expression profile of the NASH model was analyzed using RNA sequencing. Moreover, 360 NAFLD patients (steatosis, 83; NASH, 277), 40 healthy individuals, and 87 patients with alcoholic fatty liver disease were recruited.ResultsInflammatory infiltration, focal necrosis in the leaflets, steatosis, and fibrosis were documented in the mouse liver. In total, 504 genes were differentially expressed in the livers of NASH mice, and showed significant functional enrichment in the inflammation-related category. Upregulated liver LCN2 was found to be significantly interactive with various interleukins and toll-like receptors. Serum LCN2 levels were significantly increased in NAFLD patients. Serum LCN2 levels were correlated with steatosis, intralobular inflammation, semiquantitative fibrosis score, and nonalcoholic fatty liver disease activity score. The area under the curve of serum LCN2 was 0.987 with a specificity of 100% and a sensitivity of 93.5% for NASH diagnosis, and 0.977 with almost the same specificity and sensitivity for steatosis.ConclusionsLCN2 might be involved in the transition from NAFL to NASH by mediating inflammation. Serum LCN2 levels might be a novel biomarker for the diagnosis of NASH.     

Systematic transcriptome analysis reveals elevated expression of alcohol‐metabolizing genes in NAFLD livers

Obese animals and non‐alcoholic fatty liver disease (NAFLD) patients exhibit elevated blood alcohol, suggesting potential contributions of alcohol metabolism to the development of NAFLD. Liver gene expression in patients with biopsy‐proven mild (N = 40) and severe (N = 32) NAFLD were compared to that in healthy liver donors (N = 7) and alcoholic hepatitis (AH; N = 15) using microarrays. Principal components analyses (PCA) revealed similar gene expression patterns between mild and severe NAFLD which clustered with those of AH but were distinct from those of healthy livers. Differential gene expression between NAFLD and healthy livers was consistent with established NAFLD‐associated genes and NAFLD pathophysiology. Alcohol‐metabolizing enzymes including ADH, ALDH, CYP2E1, and CAT were up‐regulated in NAFLD livers. The expression level of alcohol‐metabolizing genes in severe NAFLD was similar to that in AH. The NAFLD gene expression profiles provide new directions for future investigations to identify disease markers and targets for prevention and treatment, as well as to foster our understanding of NAFLD pathogenesis and pathophysiology. Particularly, increased expression of alcohol‐metabolizing genes in NAFLD livers supports a role for endogenous alcohol metabolism in NAFLD pathology and provides further support for gut microbiome therapy in NAFLD management. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley © Sons, Ltd.     

Morphological and functional characterization of non-alcoholic fatty liver disease induced by a methionine-choline-deficient diet in C57BL/6 mice

Background: Non-alcoholic fatty liver disease (NAFLD), including non-alcoholic steatohepatitis (NASH), appears to be increasingly common worldwide. Its histopathology and the effects of nutrition on liver function have not been fully determined. Aim: To elucidate the cellular mechanisms of NAFLD induced by a methionine-choline-deficient (MCD) diet in mice. Particular focus was placed on the role of phagocytic cells. Methods: Male C57BL/6 mice were fed an MCD diet for 30 weeks. A recovery model was also established wherein a normal control diet was provided for 2 weeks after a period of 8, 16, or 30 weeks. Results: Mice fed the MCD diet for ≥2 weeks exhibited severe steatohepatitis with elevated serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. Steatohepatitis was accompanied by the infiltration of CD68-positive macrophages (Kupffer cells). The severity of steatohepatitis increased in the first 16 weeks but was seen to lessen by week 30. Fibrosis began to develop at 10 weeks and continued thereafter. Steatohepatitis and elevated serum hepatic enzyme concentrations returned to normal levels after switching the diet back to the control within the first 16 weeks, but fibrosis and CD68-positive macrophages remained. Conclusions: The histopathological changes and irreversible fibrosis seen in this model were caused by prolonged feeding of an MCD diet. These results were accompanied by changes in the activity of CD68-positive cells with temporary elevation of CCL-2, MMP-13, and MMP-9 levels, all of which may trigger early steatohepatitis and late fibrosis through phagocytosis-associated MMP induction.     

The epidemiology, pathogenesis and histopathology of fatty liver disease

Fatty liver disease includes non-alcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD), each of which is increasing in prevalence. Each represents a histological spectrum that extends from isolated steatosis to steatohepatitis and cirrhosis. NAFLD is associated with obesity, diabetes, and insulin resistance, and is considered to be the liver manifestation of the metabolic syndrome. The pathogenesis of NAFLD and ALD involves cytokines, adipokines, oxidative stress, and apoptosis. Histopathology is the gold standard for assessing the severity of liver damage in NAFLD and ALD. We have reviewed the literature, and described and compared the epidemiology, natural disease history, pathogenesis and histopathology of NAFLD and ALD.     

Vitamin D Status and Bone Mineral Density in Obese Children with Nonalcoholic Fatty Liver Disease

Whether nonalcoholic fatty liver disease (NAFLD) is related to vitamin D and bone health in obese children is unknown. The aim of this study was to evaluate vitamin D status and bone mineral density (BMD) in obese children according to their condition within the NAFLD spectrum. Anthropometric data, laboratory tests, and abdominal ultrasonography were obtained from 94 obese children. The subjects were divided into three groups according to NAFLD spectrum: normal liver, simple steatosis, and nonalcoholic steatohepatitis (NASH). Although there were no differences in vitamin D levels between the three groups, these groups showed significant differences in highly sensitive C-reactive protein (P=0.044), homeostasis model assessment of insulin resistance (HOMA-IR) (P=0.02), hepatic fibrosis scores (P<0.05), and trunk fat percentage (P=0.025). Although there were significant differences in BMDs, the age-matched BMD z-scores were not significantly different between the three groups. Serum vitamin D levels were negatively correlated with age (r=-0.368, P=0.023), serum uric acid levels (r=-0.371, P=0.022), fibrosis 4 (FIB4) (r=-0.406, P=0.011), and HOMA-IR (r=-0.530, P=0.001) in obese children with NASH. Multiple regression analysis for vitamin D in the NASH group revealed age and HOMA-IR as significant factors. In conclusion, inflammatory markers, hepatic fibrosis scores, trunk fat, and insulin resistance may reflect the spectrum of NAFLD in obese children, whereas vitamin D levels and BMD may not. In patients with NASH, however, low serum vitamin D is associated with hepatic fibrosis and insulin resistance, but not with bone health status.     

Prognostic value of high sensitivity C-reaction protein in non-insulin dependent diabetes mellitus patients with non-alcoholic fatty liver disease

Background and purpose: High sensitivity C-reaction protein (hsCRP) has been used as a significant predictive factor of cardiovascular events in patients with non-insulin dependent diabetes mellitus (NIDDM). However, existing reports in regards to the significance of hsCRP in predicting the progression of hepatic complications in NIDDM patients are too sparse to deliver clear results. This study is aimed at investigating the prognostic value of hsCRP in NIDDM patients with non-alcoholic fatty liver disease (NAFLD). Methods: 1128 NIDDM patients with a definite diagnosis of NAFLD were enrolled and followed for one year. The baseline body mass index (BMI), waist-hip circumference ratio (WHR), serum aspartate aminotransferase (AST), presence of hypertension, alanine aminotransferase (ALT), serum hsCRP, total cholesterol (Tch), fasting blood glucose (FBG), triglycerine (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and hepatitis B surface antigen (HBsAg) were recorded to analyze the significance of hsCRP in predicting the short-term progression from NAFLD to non-alcoholic steatohepatitis (NASH). Results: One year after baseline, 32% of the NAFLD patients suffered progression to NASH and the percentages of NASH were respectively 8.2%, 12.5%, 33.8% and 72.6% in 4 groups with quartered baseline serum level of hsCRP; there was significant difference among the 4 groups in percentage of NASH (P<0.001). With sex, age, WHR, BMI, hypertension, TG, TCH, HDL-C, LDL-C, FBG and HBsAg included, the calibrated regression model gave the OR values of 1.000, 1.669, 6.635 and 32.131 in in 4 quartered baseline serum levels of hsCRP. Conclusion: High serum level of hsCRP is an independent risk factor of short-term progression to NASH in patients with NIDDM and NAFLD. Those NIDDM patients with NAFLD that present with high serum level of hsCRP should be subjected to regular monitoring, lifestyle intervention and medication.     

Aberrant cytokeratin 7 expression of centrilobular hepatocytes: a clinicopathological study

Matsukuma S, Takeo H, Kono T, Nagata Y & Sato K
(2012) Histopathology  61, 857–862 Aberrant cytokeratin 7 expression of centrilobular hepatocytes: a clinicopathological study Aims: This study has attempted to elucidate the clinicopathological features of aberrant cytokeratin 7 (CK7) expression by centrilobular hepatocytes. Methods and results: A total of 113 liver biopsy specimens from patients with common non‐neoplastic liver diseases, including hepatitis B or C, non‐alcoholic steatohepatitis, alcoholic liver disease and other diseases were examined. In 56 specimens (49.6%), CK7‐positive centrilobular hepatocytes (CK7 + CHs) were identified and sometimes showed binuclear features. CK7 + CHs were associated with patients’ older age (P = 0.004), higher serum levels of aspartate aminotransferase (P = 0.016) and γ‐glutamyltransferase (P = 0.006), centrilobular fibrosis (P < 0.001), prominent thickening of hepatocytic plates (P < 0.001) and higher scores of total and periportal CK7‐positive hepatocytes (both P < 0.001), but were not correlated with gender, steatosis, serum levels of total bilirubin or alanine aminotransferase. In 55 cases of hepatitis B and hepatitis C only, CK7 + CHs were related to a higher stage of fibrosis (P = 0.006). Conclusion: CK7 + CHs occur relatively frequently in non‐neoplastic liver disease, associated with centrilobular scarring and the presence of CK7‐positive periportal hepatocytes, and appear to be a non‐specific phenomenon with respect aetiology of underlying disease. CK7 + CHs may represent age‐dependent activation of hepatic progenitor cells or a regenerative phenomenon of hepatocytes themselves, both of which might contribute to liver regeneration.     

An improved mouse model that rapidly develops fibrosis in non‐alcoholic steatohepatitis

Non‐alcoholic steatohepatitis (NASH) is a progressive fibrotic disease, the pathogenesis of which has not been fully elucidated. One of the most common models used in NASH research is a nutritional model where NASH is induced by feeding a diet deficient in both methionine and choline. However, the dietary methionine‐/choline‐deficient model in mice can cause severe weight loss and liver atrophy, which are not characteristics of NASH seen in human patients. Exclusive, long‐term feeding with a high‐fat diet (HFD) produced fatty liver and obesity in mice, but the HFD for several months did not affect fibrosis. We aimed to establish a mouse model of NASH with fibrosis by optimizing the methionine content in the HFD. Male mice were fed a choline‐deficient, L‐amino acid‐defined, high‐fat diet (CDAHFD) consisting of 60 kcal% fat and 0.1% methionine by weight. After 1–14 weeks of being fed CDAHFD, the mice were killed. C57BL/6J mice maintained or gained weight when fed CDAHFD, while A/J mice showed a steady decline in body weight (of up to 20% of initial weight). In both strains of mice, plasma levels of alanine aminotransferase increased from week 1, when hepatic steatosis was also observed. By week 6, C57BL/6J mice had developed enlarged fatty liver with fibrosis as assessed by Masson's trichrome staining and by hydroxyproline assay. Therefore, this improved CDAHFD model may be a mouse model of rapidly progressive liver fibrosis and be potentially useful for better understanding human NASH disease and in the development of efficient therapies for this condition.     

Probiotic antigens stimulate hepatic natural killer T cells

Increasing evidence suggests that gut flora play an important role in the pathogenesis of non‐alcoholic fatty liver disease (NAFLD). Our previous studies show that hepatic natural killer T (NKT) cells play a significant role in the pathogenesis of NAFLD. In this study, we explore the mechanism by which modification of gut flora leads to the alteration of hepatic NKT cells and improvement of steatosis. Mice were fed a high‐fat (HF) diet to induce NAFLD. Some of them also received different doses of mixed‐strain probiotics (VSL#3); single‐strain probiotic (Bifidobacterium infantis) or antibiotics. Animal weight, glucose tolerance, liver steatosis and hepatic NKT cells were assessed. Lipid extracts from probiotics were tested for their ability to activate NKT cells. Toll‐like receptor 4 (TLR4) knockout mice were also evaluated for their responses to HF diet. High‐dose VSL#3 was more effective than low‐dose VSL#3 and B. infantis for the improvement of hepatic NKT cell depletion and steatosis. The lipids extracted from VSL#3 stimulated NKT cells both in vivo and in vitro. In contrast, lipids from B. infantis decreased α‐GalCer‐mediated NKT cell activation in vitro, but were able to stimulate NKT cells. TLR4 knockout mice have a similar response to HF‐diet‐induced NKT cell depletion and obesity. These results suggest that alterations in the gut flora have profound effects on hepatic NKT cells and steatosis, which are both strain‐specific and dose‐dependent, but not through TLR4 signalling. Furthermore, these data suggest that probiotics may contain bacterial glycolipid antigens that directly modulate the effector functions of hepatic NKT cells.     

Interleukin-17 exacerbates hepatic steatosis and inflammation in non-alcoholic fatty liver disease

Mechanisms associated with the progression of simple steatosis to non-alcoholic fatty liver disease (NAFLD) remain undefined. Regulatory T cells (T(regs)) play a critical role in regulating inflammatory processes in non-alcoholic steatohepatitis (NASH) and because T helper type 17 (Th17) functionally oppose T(reg)-mediated responses, this study focused on characterizing the role of Th17 cells using a NAFLD mouse model. C57BL/6 mice were fed either a normal diet (ND) or high fat (HF) diet for 8 weeks. Mice in the HF group had a significantly higher frequency of liver Th17 cells compared to ND-fed mice. Neutralization of interleukin (IL)-17 in HF mice ameliorated lipopolysaccharide (LPS)-induced liver injury reflected by decreased serum alanine aminotransferase (ALT) levels and reduced inflammatory cell infiltrates in the liver. In vitro, HepG2 cells cultured in the presence of free fatty acids (FFA; oleic acid and palmitic acid) for 24 h and IL-17 developed steatosis via insulin-signalling pathway interference. IL-17 and FFAs synergized to induce IL-6 production by HepG2 cells and murine primary hepatocytes which, in combination with transforming growth factor (TGF-β), expanded Th17 cells. It is likely that a similar process occurs in NASH patients, as there were significant levels of IL-17(+) cell infiltrates in NASH patient livers. The hepatic expression of Th17 cell-related genes [retinoid-related orphan receptor gamma (ROR)γt, IL-17, IL-21 and IL-23] was also increased significantly in NASH patients compared to healthy controls. Th17 cells and IL-17 were associated with hepatic steatosis and proinflammatory response in NAFLD and facilitated the transition from simple steatosis to steatohepatitis. Strategies designed to alter the balance between Th17 cells and T(regs) should be explored as a means of preventing progression to NASH and advanced liver diseases in NAFLD patients.