The clinicopathologic spectrum and management of nonalcoholic fatty liver disease

Impact of Seipin in cholesterol mediated lipid droplet maturation; status of endoplasmic reticulum stress and lipophagy

The global prevalence of nonalcoholic fatty liver disease (NAFLD) defined by the increased number of lipid droplets (LDs) in hepatocytes, have risen continuously in parallel with the obesity. LDs and related proteins are known to affect cellular metabolism and signaling. Seipin, one of the most important LD-related proteins, plays a critical role in LD biogenesis. Although the role of adipose tissue-specific Seipin silencing is known, hepatocyte-specific silencing upon cholesterol-mediated lipid accumulation has not been investigated. In our study, we investigated the effect of Seipin on endoplasmic reticulum (ER) stress and lipophagy in cholesterol accumulated mouse hepatocyte cells. In this direction, cholesterol accumulation was induced by cholesterol-containing liposome, while Seipin mRNA and protein levels were reduced by siRNA. Our findings show that cholesterol containing liposome administration in hepatocytes increases both Seipin protein and number of large LDs. However Seipin silencing reduced the increase of cholesterol mediated large LDs and Glucose-regulated protein 78 (GRP78) mRNA. Additionally, lysosome-LD colocalization increased only in cells treated with cholesterol containing liposome, while the siRNA against Seipin did not lead any significant difference. According to our findings, we hypothesize that Seipin silencing in hepatocytes reduced cholesterol mediated LD maturation as well as GRP78 levels, but not lipophagy.

One-hour post-load glucose levels are associated with hepatic steatosis assessed by transient elastography

AIM

To examine the association between 1-hour plasma glucose (PG) concentration and markers of non-alcoholic fatty liver disease (NAFLD) assessed by transient elastography (TE).

METHODS

We performed TE in 107 metabolically well-characterized non-diabetic White individuals. Controlled attenuation parameter (CAP) was used to quantify liver steatosis, while liver stiffness marker (LS) was used to evaluate fibrosis.

RESULTS

Controlled attenuation parameter correlated significantly with 1-hour PG (r = 0.301, P < 0.01), fasting insulin (r = 0.285, P < 0.01), 2-hour insulin (r = 0.257, P < 0.02), homeostasis model assessment index of insulin resistance (r = 0.252, P < 0.01), high-density lipoprotein cholesterol (r = -0.252, P < 0.02), body mass index (BMI; r = 0.248, P < 0.02) and age (r = 0.212, P < 0.03), after correction for age, sex and BMI. In a multivariable linear regression analysis, 1-hour PG (β = 0.274, P = 0.008) and fasting insulin levels (β = 0.225, P = 0.029) were found to be independent predictors of CAP. After excluding subjects with prediabetes, 1-hour PG was the sole predictor of CAP variation (β = 0.442, P < 0.001). In a logistic regression model, we observed that the group with 1-hour PG ≥  8.6 mmol/L (155 mg/dL) had a significantly higher risk of steatosis (odds ratio 3.98, 95% confidence interval 1.43-11.13; P = 0.008) than individuals with 1-hour PG <  8.6 mmol/L, after correction for potential confounders. No association was observed between 1-hour PG and LS.

CONCLUSION

Our data confirm that 1-hour PG ≥  8.6 mmol/L is associated with higher signs of NAFLD, even among individuals with normal glucose tolerance, categorized as low risk by canonical diagnostic standards. TE is a safe low-impact approach that could be employed for stratifying the risk profile in these patients, with a high level of accuracy.

Cholesterol Exacerbates the Pathophysiology of Non-Alcoholic Steatohepatitis by Upregulating Hypoxia-Inducible Factor 1 and Modulating Microcirculatory Dysfunction

Cholesterol is a pivotal lipotoxic molecule that contributes to the progression of Non-Alcoholic Steatohepatitis NASH). Additionally, microcirculatory changes are critical components of Non-Alcoholic Fatty Liver Disease (NAFLD) pathogenesis. This study aimed to investigate the role of cholesterol as an insult that modulates microcirculatory damage in NAFLD and the underlying mechanisms. The experimental model was established in male C57BL/6 mice fed a high-fat high-carbohydrate (HFHC) diet for 39 weeks. Between weeks 31-39, 2% cholesterol was added to the HFHC diet in a subgroup of mice. Leukocyte recruitment and hepatic stellate cells (HSC) activation in microcirculation were assessed using intravital microscopy. The hepatic microvascular blood flow (HMBF) was measured using laser speckle flowmetry. High cholesterol levels exacerbated hepatomegaly, hepatic steatosis, inflammation, fibrosis, and leukocyte recruitment compared to the HFHC group. In addition, cholesterol decreased the HMBF-cholesterol-induced activation of HSC and increased HIF1A expression in the liver. Furthermore, cholesterol promoted a pro-inflammatory cytokine profile with a Th1-type immune response (IFN-γ/IL-4). These findings suggest cholesterol exacerbates NAFLD progression through microcirculatory dysfunction and HIF1A upregulation through hypoxia and inflammation. This study highlights the importance of cholesterol-induced lipotoxicity, which causes microcirculatory dysfunction associated with NAFLD pathology, thus reinforcing the potential of lipotoxicity and microcirculation as therapeutic targets for NAFLD.

Farnesoid X receptor in chronic liver diseases: an immunohistochemical study

Chronic hepatitis C virus (HCV) related liver diseases are still an ongoing cause of hepatic failure despite the effective role of direct-acting anti-viral agents. Farnesoid X receptor (FXR) agonists have a potential therapeutic effect on the management of chronic liver diseases (CLD). However, data regarding FXR protein expression in human CLDs are limited and conflicting. We aimed to assess the immunohistochemical expression of FXR in HCV-related chronic hepatitis and cirrhosis in comparison with metabolic-associated fatty liver disease (MAFLD) and normal liver tissue. The expression of FXR was low both in hepatocytes and bile ducts of HCV-related chronic hepatitis and cirrhosis (p = .001, respectively). In addition, a significantly low expression of FXR was observed in HCV-related hepatitis and cirrhosis groups compared to MAFLD in hepatocytes (p < .001, for both) and bile ducts (p = .004 and p = .018). FXR expression in HCV-related cirrhosis was significantly associated with compensated liver function (p = .032) and low inflammatory activity (p = .022). FXR expression decreases in HCV-related CLDs. There was some evidence that FXR expression could protect against post-hepatitis cirrhosis.

Polyunsaturated and Saturated Oxylipin Plasma Levels Allow Monitoring the Non-Alcoholic Fatty Liver Disease Progression to Severe Stages

Hepatic fat accumulation is the hallmark of non-alcoholic fatty liver disease (NAFLD). Our aim was to determine the plasma levels of oxylipins, free polyunsaturated fatty acids (PUFA) and markers of lipid peroxidation in patients with NAFLD in progressive stages of the pathology. Ninety 40–60-year-old adults diagnosed with metabolic syndrome were distributed in without, mild, moderate or severe NAFLD stages. The free PUFA and oxylipin plasma levels were determined by the UHPLC–MS/MS system. The plasma levels of oxylipins produced by cyclooxygenases, lipoxygenases and cytochrome P450, such as prostaglandin 2α (PGF2α), lipoxinB4 and maresin-1, were higher in severe NAFLD patients, pointing to the coexistence of both inflammation and resolution processes. The plasma levels of the saturated oxylipins 16-hydroxyl-palmitate and 3-hydroxyl-myristate were also higher in the severe NAFLD patients, suggesting a dysregulation of oxidation of fatty acids. The plasma 12-hydroxyl-estearate (12HEST) levels in severe NAFLD were higher than in the other stages, indicating that the hydroxylation of saturated fatty acid produced by reactive oxygen species is more present in this severe stage of NAFLD. The plasma levels of 12HEST and PGF2α are potential candidate biomarkers for diagnosing NAFLD vs. non-NAFLD. In conclusion, the NAFLD progression can be monitored by measuring the plasma levels of free PUFA and oxylipins characterizing the different NAFLD stages or the absence of this disease in metabolic syndrome patients.

Alterations in circulating lipidomic profile in patients with type 2 diabetes with or without non-alcoholic fatty liver disease

Objective: Non-alcoholic fatty liver disease (NAFLD) and Type 2 diabetes mellitus (T2DM) often coexist and drive detrimental effects in a synergistic manner. This study was designed to understand the changes in circulating lipid and lipoprotein metabolism in patients with T2DM with or without NAFLD. Methods: Four hundred thirty-four T2DM patients aged 18-60 years were included in this study. Fatty liver was assessed by FibroScan. The comprehensive metabolic lipid profiling of serum samples was assessed by using high-throughput proton NMR metabolomics. Results: Our data revealed a significant association between steatosis and serum total lipids in VLDL and LDL lipoprotein subclasses, while total lipids in HDL subclasses were negatively associated. A significant positive association was found between steatosis and concentration of lipids, phospholipids, cholesterol, and triglycerides in VLDL and LDL subclasses, while HDL subclasses were negatively associated. Furthermore, a significant, association was observed between fibrosis and concentrations of lipids, phospholipids, cholesterol, and triglycerides in very small VLDL, large, and very large HDL subclasses. Subgroup analysis revealed a decrease in the concentrations of lipids, phospholipids, cholesterol, and other lipid biomolecules in patients using antilipemic medications. Conclusion: The metabolomics results provide evidence that patients with T2DM with higher steatosis grades have altered lipid metabolomics compared to patients without steatosis. Increased lipid, phospholipids, cholesterol, and triglycerides concentration of VLDL and LDL subclasses are associated with steatosis in patients with T2DM.

Generation of a Diet-Induced Mouse Model of Nonalcoholic Fatty Liver Disease

The obesity epidemic is driving the increased prevalence of nonalcoholic fatty liver disease (NAFLD) globally. The more aggressive subtype of NAFLD, nonalcoholic steatohepatitis (NASH), can lead to progressive disease and ultimately lead to cirrhosis, liver cancer, and death. There are many unmet needs in the field of NAFLD including understanding of molecular mechanisms driving disease, natural history, risk for liver cancer, and most importantly FDA approved therapeutics. Animal models serve as a tool to aid in answering some of these questions. Here, we describe the diet-induced animal model of NAFLD (DIAMOND), a mouse model with many characteristics that mimic human NASH.

Association of Cardiovascular Risk Factors and Metabolic Syndrome with non-alcoholic and alcoholic fatty liver disease: a retrospective analysis

BACKGROUND

Although many studies on non-alcoholic fatty liver disease (NAFLD) are underway worldwide, and several existing studies have investigated the association between NAFLD and cardiovascular risk factors, studies comparing NAFLD and alcoholic fatty liver disease (AFLD) are scarce. This study aimed to evaluate differences between the incidence of cardiovascular risk factors and metabolic syndrome in NAFLD and AFLD.

METHODS

A retrospective analysis of 913 patients who underwent abdominal computed tomography (CT) was performed to compare the incidence of cardiovascular risk factors and metabolic syndrome between NAFLD and AFLD. Subjects were divided into three groups based on criteria: healthy (n = 572), NAFLD (n = 295), and AFLD (n = 46). The healthy group had no liver disease. NAFLD was defined as fatty liver diagnosed on CT and drinking less than 140 g/week for men or 70 g/week for women. AFLD was defined as fatty liver diagnosed on CT and drinking more than 140 g/week for men or 70 g/week for women. We compared the incidence of cardiovascular risk factors and metabolic syndrome between the three groups. The relationship between each group and the metabolic syndrome risk was analyzed through multivariate logistic regression analysis.

RESULTS

No significant differences in several cardiovascular risk factors were observed between the NAFLD and AFLD groups. Upon analyzing the metabolic syndrome status in each group after making appropriate adjustments, the odds ratios (ORs) in the NAFLD (OR = 2.397, P = 0.002) and AFLD groups (OR = 4.445, P = 0.001) were found to be significantly higher than that in the healthy group; the incidence rate of metabolic syndrome was similar in the NAFLD and AFLD groups.

CONCLUSIONS

Both the NAFLD and AFLD groups had more cardiovascular risk factors and higher metabolic syndrome risk than the healthy group. Thus, the prevention of fatty liver disease, regardless of the specific type, should involve the identification of cardiovascular and metabolic syndrome risk factors. If abdominal CT reveals a fatty liver, whether NAFLD or AFLD, the risk of cardiovascular disease and metabolic syndrome should be assessed.

A New Endemic of Concomitant Nonalcoholic Fatty Liver Disease and Chronic Hepatitis B

Hepatitis B virus (HBV) infection remains a global public problem despite the availability of an effective vaccine. In the past decades, nonalcoholic fatty liver disease (NAFLD) has surpassed HBV as the most common cause of chronic liver disease worldwide. The prevalence of concomitant chronic hepatitis B (CHB) and NAFLD thus reaches endemic proportions in geographic regions where both conditions are common. Patients with CHB and NAFLD are at increased risk of liver disease progression to cirrhosis and hepatocellular carcinoma. Due to the complexity of the pathogenesis, accurate diagnosis of NAFLD in CHB patients can be challenging. Liver biopsy is considered the gold standard for diagnosing and determining disease severity, but it is an invasive procedure with potential complications. There is a growing body of literature on the application of novel noninvasive serum biomarkers and advanced radiological modalities to diagnose and evaluate NAFLD, but most have not been adequately validated, especially for patients with CHB. Currently, there is no approved therapy for NAFLD, although many new agents are in different phases of development. This review provides a summary of the epidemiology, clinical features, diagnosis, and management of the NAFLD and highlights the unmet needs in the areas of CHB and NAFLD coexistence.

Lipidomics in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), the most common chronic liver disorder in Western countries, comprises steatosis to nonalcoholic steatohepatitis (NASH), with the latter having the potential to progress to cirrhosis. The transition from isolated steatosis to NASH is still poorly understood, but lipidomics approach revealed that the hepatic lipidome is extensively altered in the setting of steatosis and steatohepatitis and these alterations correlate with disease progression. Recent data suggest that both quantity and quality of the accumulated lipids are involved in pathogenesis of NAFLD. Changes in glycerophospholipid, sphingolipid, and fatty acid composition have been described in both liver biopsies and plasma of patients with NAFLD, implicating that specific lipid species are involved in oxidative stress, inflammation, and cell death. In this article, we summarize the findings of main human lipidomics studies in NAFLD and delineate the currently available information on the pathogenetic role of each lipid class in lipotoxicity and disease progression.

Diagnostic Performance of Ultrasonography in Detecting Fatty Liver Disease in Comparison with Fibroscan in People Suspected of Fatty Liver

Background:

Fatty liver disease is a common hepatic disorder that remains undiagnosed due to the high number of asymptomatic patients and lack of a proper noninvasive diagnostic tool. Liver biopsy, the gold standard of liver steatosis diagnosis, is an invasive method that can be replaced by fibroscan. Fibroscan can detect liver steatosis with high sensitivity and specificity, but it is not accessible around the world. In this study, we compared ultrasonography (US) as a cheap and accessible device with fibroscan method in detecting patients with liver steatosis.

Materials and Methods:

We enrolled 77 patients in this study. US and fibroscan were done in each patient at a single day. Liver steatosis stages were recorded using US and fibroscan. The diagnostic performance of US was calculated, using fibroscan as the reference method.

Results:

The sensitivity and specificity of US in detecting fatty liver disease using fibroscan as a standard method were 73% and 69%, respectively.

Conclusion:

Based on sensitivity and specificity achieved from US, this study suggests that ultrasound is a suitable method for detecting patients with liver steatosis obviating liver biopsy and fibroscan.

Dihydromyricetin Ameliorates Nonalcoholic Fatty Liver Disease by Improving Mitochondrial Respiratory Capacity and Redox Homeostasis Through Modulation of SIRT3 Signaling

Aims: Our previous clinical trial indicated that the flavonoid dihydromyricetin (DHM) could improve hepatic steatosis in patients with nonalcoholic fatty liver disease (NAFLD), altough the potential mechanisms of these effects remained elusive. Here, we investigated the hepatoprotective role of DHM on high-fat diet (HFD)-induced NAFLD. Results: DHM supplementation could effectively ameliorate the development of NAFLD by inhibiting hepatic lipid accumulation both in HFD-fed wild-type mice and in palmitic acid-induced hepatocytes. We reveal for the first time that mitochondrial dysfunction characterized by ATP depletion and augmented oxidative stress could be reversed by DHM treatment. Moreover, DHM enhanced the mitochondrial respiratory capacity by increasing the expression and enzymatic activities of mitochondrial complexes and increased mitochondrial reactive oxygen species scavenging by restoring manganese superoxide dismutase (SOD2) activity. Interestingly, the benefits of DHM were abrogated in SIRT3 knockout (SIRT3KO) mice and in hepatocytes transfected with SIRT3 siRNA or treated with an SIRT3-specific inhibitor. We further showed that DHM could increase SIRT3 expression by activating the adenosine monophosphate-activated protein kinase (AMPK)-peroxisome proliferator-activated receptor-γ coactivator-1 alpha (PGC1α)/estrogen-related receptor-α (ERRα) signaling pathway. Innovation: Our work indicates that SIRT3 plays a critical role in the DHM-mediated beneficial effects that include ameliorating mitochondrial dysfunction and oxidative stress in a nutritional NAFLD model both in vivo and in vitro.Conclusion: Our results suggest that DHM prevents NAFLD by improving mitochondrial respiratory capacity and redox homeostasis in hepatocytes through a SIRT3-dependent mechanism. These results could provide a foundation to identify new DHM-based preventive and therapeutic strategies for NAFLD.

Association between hepatic steatosis and the development of hepatocellular carcinoma in patients with chronic hepatitis B

Background/Aims

Nonalcoholic fatty liver disease (NAFLD) is becoming a worldwide epidemic, and is frequently found in patients with chronic hepatitis B (CHB). We investigated the impact of histologically proven hepatic steatosis on the risk for hepatocellular carcinoma (HCC) in CHB patients without excessive alcohol intake.

Methods

Consecutive CHB patients who underwent liver biopsy from January 2007 to December 2015 were included. The association between hepatic steatosis (≥ 5%) and subsequent HCC risk was analyzed. Inverse probability weighting (IPW) using the propensity score was applied to adjust for differences in patient characteristics, including metabolic factors.

Results

Fatty liver was histologically proven in 70 patients (21.8%) among a total of 321 patients. During the median (interquartile range) follow-up of 5.3 (2.9–8.3) years, 17 of 321 patients (5.3%) developed HCC: 8 of 70 patients (11.4%) with fatty liver and 9 of 251 patients (3.6%) without fatty liver. The five-year cumulative incidences of HCC among patients without and with fatty liver were 1.9% and 8.2%, respectively (P=0.004). Coexisting fatty liver was associated with a higher risk for HCC (adjusted hazards ratio [HR], 3.005; 95% confidence interval [CI], 1.122–8.051; P=0.03). After balancing with IPW, HCC incidences were not significantly different between the groups (P=0.19), and the association between fatty liver and HCC was not significant (adjusted HR, 1.709; 95% CI, 0.404–7.228; P=0.47).

Conclusions

Superimposed NAFLD was associated with a higher HCC risk in CHB patients. However, the association between steatosis per se and HCC risk was not evident after adjustment for metabolic factors.

Circulating Phospholipid Patterns in NAFLD Patients Associated with a Combination of Metabolic Risk Factors

Background: Non-alcoholic fatty liver disease (NAFLD) is associated with inefficient macro- and micronutrient metabolism, and alteration of circulating phospholipid compositions defines the signature of NAFLD. This current study aimed to assess the pattern of serum phospholipids in the spectrum of NAFLD, and its related comorbidities and genetic modifications. Methods: 97 patients with diagnosed NAFLD were recruited at a single center during 2013–2016. Based on histological and transient elastography assessment, 69 patients were divided into non-alcoholic steatohepatitis (NASH) and non-alcoholic fatty liver (NAFL) subgroups. 28 patients served as healthy controls. Serum phospholipids were determined by liquid-chromatography mass spectrometry (LC-MS/MS). Results: The total content of phosphatidylcholine (PC) and sphingomyelin in the serum was significantly increased in NAFL and NASH patients, compared to healthy controls. In addition, serum lysophospatidylethanolamine levels were significantly decreased in NAFL and NASH individuals. Circulating PC species, containing linoleic and α-linolenic acids, were markedly increased in NAFLD patients with hypertension, compared to NAFLD patients without hypertension. The pattern of phospholipids did not differ between NAFLD patients with diabetes and those without diabetes. However, NAFLD patients with hyperglycemia (blood glucose level (BGL) >100 mg/dL) exhibited significantly a higher amount of monounsaturated phosphatidylethanolamine than those with low blood glucose levels. In addition, NAFLD patients with proven GG-genotype of PNPLA3, who were at higher risk for the development of progressive disease with fibrosis, showed lower levels of circulating plasmalogens, especially 16:0, compared to those with CC- and CG-allele. Conclusions: Our extended lipidomic study presents a unique metabolic profile of circulating phospholipids associated with the presence of metabolic risk factors or the genetic background of NAFLD patients.

Resting and Exercise Energy Metabolism After Liver Transplantation for Nonalcoholic Steatohepatitis

Background

Nonalcoholic steatohepatitis (NASH) is a leading indication for liver transplantation (LT). We hypothesized that weight gain after LT may be exacerbated by reduced metabolic rates due to the LT procedure, particularly during exercise. We aimed to compare resting and exercise energy expenditure between patients transplanted for NASH and nontransplant nonalcoholic fatty liver disease (NAFLD) subjects.

Methods

NASH LT recipients (>1-year post, n = 14) and NAFLD controls (n = 13) underwent analysis of body composition, resting energy expenditure (REE), and exercise energy expenditure (VO_2max), the latter using a ramped-Bruce protocol assessed by expired gas analysis and peak heart rate.

Results

Participants were mean 61.5 ± 7.9 years, 48.1% men, and 66.7% white. Baseline comorbidities were similar between groups. Among men, mean REE adjusted for total (17.7 vs 18.8, P = 0.87) and lean body mass (23.5 vs 26.9, P = 0.26), as well as VO₂ (20.1 vs 23.9, P = 0.29), was lower in NASH LT recipients compared with NAFLD controls, respectively, although not statistically significant. However, female NASH LT recipients had significantly lower mean REE than NAFLD controls when adjusted for total (14.2 vs 18.9, P = 0.01) and lean body mass (19.3 vs 26.5, P = 0.002), as well as significantly lower VO_2max (14.4 vs 20.6, P = 0.017).

Conclusions

NASH LT recipients, particularly women, have lower REE and exercise energy expenditure compared with nontransplant NAFLD patients. More aggressive diet and exercise programs for post-LT NASH recipients to account for reduced resting and exercise metabolic rates may attenuate weight gain in this vulnerable population.

Proteomic profiling of cellular steatosis with concomitant oxidative stress in vitro

Background

Nutrient excess underpins the development of nonalcoholic fatty liver disease (NAFLD). The ensuing metabolic derangement is characterised by increased cellular respiration, oxidative stress and mitochondrial impairment. We have previously recapitulated these events in an in vitro cellular steatosis model. Here, we examined the distinct patterns of protein expression involved using a proteomics approach.

Methods

Human hepatoblastoma C3A cells were treated with a combination of energy substrates; lactate (L), pyruvate (P), octanoate (O) and ammonia (N). Proteins extracts were trypsinized and analyzed on a capillary HPLC OrbitrapXL mass spectrometer. Proteins were quantified using a label-free intensity based approach. Functional enrichment analysis was performed using ToppCluster via Gene Ontology (GO) database.

Results

Of the 1327 proteins identified, 104 were differentially expressed between LPON and untreated cells (defined as: ≥2 peptides; fold change ≥1.5; p-value <0.05). Seventy of these were upregulated with LPON. Functional enrichment analysis revealed enhanced protein biosynthesis accompanied by downregulation of histones H2A type 1-A, H1.2, H1.5 and H1.0I in LPON cells. Lipid binding annotations were also enriched as well as proteins involved in cholesterol synthesis, uptake and efflux. Increased expression of aldo-keto reductase family 1, member C1 and C3 suggests enhanced sterol metabolism and increased ROS-mediated lipid peroxidation.

Conclusions

The surge of energy substrates diverts free fatty acid metabolism towards pathways that can mitigate lipotoxicity. The histones depletion may represent an adaptation to increased protein synthesis. However, this can also expose DNA to oxidative stress thus should be explored further in the context of NAFLD progression.

Fatty acid metabolism is altered in non-alcoholic steatohepatitis independent of obesity

BACKGROUND

Non-alcoholic steatohepatitis (NASH) is associated with changes in fatty acid (FA) metabolism. However, specific changes in metabolism and hepatic mRNA expression related to NASH independent of simple steatosis, obesity and diet are unknown.

METHODS

Liver histology, serum and liver FA composition and estimated enzyme activities based on the FA ratios in cholesteryl esters and triglycerides were assessed in 92 obese participants of the Kuopio Obesity Surgery Study (KOBS) divided to those with normal liver, steatosis or NASH (30 men and 62 women, age 46.8±9.5years (mean±SD), BMI 44.2±6.2kg/m(2)). Plasma FA composition was also investigated in the Metabolic Syndrome in Men (METSIM) Study (n=769), in which serum alanine aminotransferase (ALT) was used as a marker of liver disease.

RESULTS

Obese individuals with NASH had higher activity of estimated activities of delta-6 desaturase (D6D, p<0.002) and stearoyl-CoA desaturase 1 (SCD1, p<0.002) and lower activity of delta-5 desaturase (D5D, p<0.002) when compared to individuals with normal liver. Estimated activities of D5D, D6D and SCD1 correlated positively between liver and serum indicating that serum estimates reflected liver metabolism. Accordingly, NASH was associated with higher hepatic mRNA expression of corresponding genes FADS1, FADS2 and SCD. Finally, differences in FA metabolism that associated with NASH in obese individuals were also associated with high ALT in the METSIM Study.

CONCLUSIONS

We demonstrated alterations in FA metabolism and endogenous desaturase activities that associate with NASH, independent of obesity and diet. This suggests that changes in endogenous FA metabolism are related to NASH and that they may contribute to the progression of the disease.

Endoplasmic Reticulum Stress Is Implicated in Intestinal Failure-Associated Liver Disease

BACKGROUND

Intestinal failure-associated liver disease (IFALD) is the most serious consequence of long-term parenteral nutrition for intestinal failure. Little is known about the pathogenesis of IFALD, although many of the risk factors are also linked to endoplasmic reticulum stress (ERS). We propose that ERS may have a role in the development of IFALD.

METHODS

Archived liver tissue from patients with early and late IFALD, as well as from normal controls, was used for RNA extraction and immunohistochemistry to demonstrate the presence of ERS markers.

RESULTS

Mean relative RNA levels of glucose regulatory protein 78 in normal liver (n = 3), early IFALD (n = 15), and late IFALD (n = 5) were 0.5, 37.86, and 212.11, respectively. Mean relative expression of ERDj4 (ER DnaJ homologue 4, a downstream ERS effector) in normal liver, early IFALD, and late IFALD was 5.51, 216.68, and 213.22, respectively. The degree of splicing of X-box binding protein 1 in IFALD compared with normal liver was significantly higher (mean, 0.0779 normal, 0.102 early IFALD, 0.2063 late IFALD).

CONCLUSIONS

This is the first description of ERS in IFALD. This information may open up new therapeutic possibilities in the form of chemical chaperones known to ameliorate ERS.

Effects of fat accumulation in the liver on hemodynamic variables assessed by Doppler ultrasonography

PURPOSE

To investigate the effect of various degrees of fatty liver infiltration on hepatic hemodynamics using Doppler ultrasonography.

METHODS

We included 40 patients with hepatic steatosis and 20 healthy volunteers. Hepatic steatosis was quantified by a chemical shift MRI. Hepatic artery peak systolic and end-diastolic velocity, resistance index (RI) and pulsatility index (PI), hepatic vein RI and PI, portal vein RI, PI, congestion index, and peak maximum velocity were evaluated by Doppler ultrasonography. The hepatic vein waveforms were classified as triphasic, biphasic, or monophasic. Kruskal-Wallis test was performed for comparing more than two groups. If significant differences were found, Mann-Whitney U test with Bonferroni correction was performed for pair-wise comparisons. Pearson &gch;(2) and Fisher's exact tests were used to compare categorical variables.

RESULTS

According to MRI, 15 patients had mild, 14 patients had moderate, and 11 patients had severe fatty infiltration. Portal vein peak maximum velocity was median: 19.8 (range 12-33.3), 21.1 (8-41.8), 16.6 (10.6-24.9), and 29.2 (14.1-40.4) cm/s. Congestion index was 0.05 (0.02-0.16), 0.07 (0.01-0.17), 0.11 (0.06-0.24), and 0.05 (0.02-0.16). Hepatic artery RI was 0.75 (0.56-1.00), 0.66 (0.52-0.87), 0.83 (0.38-1.00), and 0.76 (0.48-2.76), and PI was 1.83 (0.90-3.13), 1.38 (1.04-2.63), 1.97 (0.86-2.90), and 1.82 (0.70-2.90) (p = .046 and p = .036) in the mild, moderate, severe steatosis, and control groups, respectively. The rate of triphasic hepatic vein waveforms was higher in controls than in patients with severe steatosis.

CONCLUSIONS

Portal vein flow velocity decreases in severe hepatic steatosis when compared with controls.

Chronic hepatitis C virus infection: it is not only about the liver

BACKGROUND AND AIMS

Although hepatitis B virus (HBV) and hepatitis C virus (HCV) are both hepatotropic and quite similar in terms of clinical manifestations and histopathology, their respective infections are distinct in terms of epidemiology and prognosis. Recognizing the differences between patients with HBV and HCV infection with respect to demographic characteristics, prevalence of comorbidities, and presence of lifestyle factors aids the proper treatment of these patients. We aimed to compare two populations with chronic viral liver disease (chronic HCV and chronic HBV), each of them with resolved hepatitis C.

PATIENTS AND METHODS

We included patients referred to a municipal reference clinic from March 2009 through May 2012. Patient data were collected using standardized questionnaires at the patients' first visit to clinic. Questionnaires included epidemiological information, presence of comorbidities, and lifestyle.

RESULTS

A total of 756 patients were included in the study, 348 (46.0%) with chronic HCV infection, 176 (23.3%) with chronic HBV infection, and 232 (30.7%) with resolved HCV infection. Multivariate analysis including patients with chronic HCV infection and chronic HBV infection indicated that age [adjusted odds ratio (AOR)=1.06; 95% confidence interval (CI): 1.03-1.08], alcohol abuse (AOR=1.58; 95% CI: 1.01-2.49), smoking (AOR=1.64; 95% CI: 1.00-2.17), and illicit drug (AOR=2.92; 95% CI: 1.69-5.02) use were associated independently with chronic HCV infection. Multivariate analyses including patients with chronic HCV infection and those patients with resolved HCV infection, presence of at least one comorbidity (AOR=1.94; 95% CI: 1.12-3.3), illicit drug use (AOR=3.24; 95% CI: 1.90-5.54), and age (AOR=1.03; 95% CI: 1.01-1.05) were independently associated with chronic HCV infection. Age (AOR=0.98; 95% CI: 0.96-0.99) and male sex (AOR=1.93; 95% CI: 1.26-2.95) were the only variables associated significantly with chronic HBV infection in the multivariate analysis between patients with chronic HBV infection and resolved HCV infection.

CONCLUSION

Our results highlight that patients with chronic HCV infection are complex and require a multidisciplinary approach during patient follow-up and clinical management.

Three cases of glycogenic hepatopathy mimicking acute and relapsing hepatitis in type I diabetes mellitus

Glycogenic hepatopathy (GH) is an uncommon cause of serum transaminase elevation in type I diabetes mellitus (DM). The clinical signs and symptoms of GH are nonspecific, and include abdominal discomfort, mild hepatomegaly, and transaminase elevation. In this report we describe three cases of patients presenting serum transaminase elevation and hepatomegaly with a history of poorly controlled type I DM. All of the cases showed sudden elevation of transaminase to more than 30 times the upper normal range (like in acute hepatitis) followed by sustained fluctuation (like in relapsing hepatitis). However, the patients did not show any symptom or sign of acute hepatitis. We therefore performed a liver biopsy to confirm the cause of liver enzyme elevation, which revealed GH. Clinicians should be aware of GH so as to prevent diagnostic delay and misdiagnosis, and have sufficient insight into GH; this will be aided by the present report of three cases along with a literature review.

In vivo hepatic lipid quantification using MRS at 7 Tesla in a mouse model of glycogen storage disease type 1a

The assessment of liver lipid content and composition is needed in preclinical research to investigate steatosis and steatosis-related disorders. The purpose of this study was to quantify in vivo hepatic fatty acid content and composition using a method based on short echo time proton magnetic resonance spectroscopy (MRS) at 7 Tesla. A mouse model of glycogen storage disease type 1a with inducible liver-specific deletion of the glucose-6-phosphatase gene (L-G6pc(-/-)) mice and control mice were fed a standard diet or a high-fat/high-sucrose (HF/HS) diet for 9 months. In control mice, hepatic lipid content was found significantly higher with the HF/HS diet than with the standard diet. As expected, hepatic lipid content was already elevated in L-G6pc(-/-) mice fed a standard diet compared with control mice. L-G6pc(-/-) mice rapidly developed steatosis which was not modified by the HF/HS diet. On the standard diet, estimated amplitudes from olefinic protons were found significantly higher in L-G6pc(-/-) mice compared with that in control mice. L-G6pc(-/-) mice showed no noticeable polyunsaturation from diallylic protons. Total unsaturated fatty acid indexes measured by gas chromatography were in agreement with MRS measurements. These results showed the great potential of high magnetic field MRS to follow the diet impact and lipid alterations in mouse liver.

Antioxidant therapy in nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) affects up to 3% of the North American population. It occurs as a manifestation of the insulin-resistant state and oxidative stress is thought to be a key component of its pathophysiology. Exercise and diet, which are the mainstay of therapy, are difficult to achieve and maintain with a disappointing long-term compliance record. There is growing literature on the potential for antioxidant therapy. The recent literature strongly suggests that vitamin E supplementation and other putative free radical scavengers and/or antioxidants are beneficial in improving biochemical and histological parameters in NASH.

Review article: is non-alcoholic fatty liver disease a spectrum, or are steatosis and non-alcoholic steatohepatitis distinct conditions?

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is currently conceptualised as a clinical spectrum that results from a ‘multiple-hit’ process which begins with simple steatosis and subsequently renders the hepatocytes susceptible to a variety of insults. Ultimately, more serious liver injuries like non-alcoholic steatohepatitis (NASH) and cirrhosis may develop. Although the metabolic syndrome is considered the crucial player in the pathogenesis of NAFLD, recent studies have highlighted novel pathophysiological mechanisms in this clinical entity.

AIM

To discuss the pathophysiology of NAFLD based on the hypothesis that simple steatosis and NASH are discrete entities rather than two points on a spectrum.

METHODS

A literature search was conducted in August 2012 on PubMed, Ovid Embase, Ovid Medline and Scopus using the following search terms: steatosis, non-alcoholic steatohepatitis, pathophysiology, fatty liver, natural history and genetics.

RESULTS

Simple steatosis and NASH appear as two distinct pathophysiological entities and progression from pure fatty liver to NASH appears to be so rare as to warrant publication. The possible pathogenetic pathways specifically related to NASH are highlighted.

CONCLUSIONS

Although simple steatosis and non-alcoholic steatohepatitis are currently viewed as two histological subtypes of the unique spectrum of non-alcoholic fatty liver disease, the two conditions are likely distinct not only from a histological but also from a pathophysiological standpoint. Efforts to distinguish simple steatosis from non-alcoholic steatohepatitis using non-invasive modalities should be informed by the current pathophysiology of these two clinical entities.

Oxidative stress rather than triglyceride accumulation is a determinant of mitochondrial dysfunction in in vitro models of hepatic cellular steatosis

BACKGROUND/AIMS

There is still debate about the relationship between fat accumulation and mitochondrial function in nonalcoholic fatty liver disease. It is a critical question as only a small proportion of individuals with steatosis progress to steatohepatitis. In this study, we focused on defining (i) the effects of triglyceride accumulation and reactive oxygen species (ROS) on mitochondrial function (ii) the contributions of triglyceride, ROS and subsequent mitochondrial impairment on the metabolism of energy substrates.

METHODS

Human hepatoblastoma C3A cells, were treated with various combinations of oleate, octanoate, lactate (L), pyruvate (P) and ammonia (N) acutely or for 72 h, before measurements of triglyceride concentration, cell respiration, ROS production, mitochondrial membrane potential, ketogenesis and gluconeogenesis, TCA cycle metabolite analysis and electron microscopy.

RESULTS

Acutely, LPON treatment enhanced mitochondrial respiration and ROS formation. After 72 h, despite the similarities in triglyceride accumulation, LPON treatment, but not oleate, dramatically affected mitochondrial function as evidenced by decreased respiration, increased mitochondrial membrane potential and ROS formation with concomitant enhanced ketogenesis. By comparison, respiration and ROS formation remained unperturbed with oleate. Importantly, this was accompanied by an increased gluconeogenesis and ketogenesis. The addition of the antioxidant N-acetyl-L-cysteine prevented mitochondrial dysfunction and reversed metabolic changes seen with LPON, strongly suggesting ROS involvement in mediating mitochondrial impairment.

CONCLUSIONS

Our data indicate that ROS formation, rather than cellular steatosis per se, impairs mitochondrial function. Thus, reduction in cellular steatosis may not always be the desired outcome without concomitant improvement in mitochondrial function and/or reducing of ROS formation.

A critical analysis of three quantitative methods of assessment of hepatic steatosis in liver biopsies

The issue of adequately quantitatively evaluating hepatic steatosis is still unresolved. Therefore, we compared three methods of quantitative assessment. Two groups of mice (n = 10 each) were fed standard chow (10% fat, SC group) or a high-fat diet (60% fat, HF group) for 16 weeks, and hepatic triglyceride (HT) and liver tissue were then studied. Paraplast-embedded tissues stained by hematoxylin and eosin (H-E) were compared to frozen sections stained by Oil Red-O (ORO). In addition, the volume density of steatosis (Vv[steatosis, liver]) was measured by point counting (P-C, sections H-E or ORO) or by image analysis (I-A, sections ORO). HT was significantly higher in the HF group (104% greater, P = 0.0004) than in the SC group. With P-C and H-E, Vv[steatosis, liver] was 4.80 ± 0.90% in the SC group and 33.50 ± 3.17% in the HF group (600% greater, P < 0.0001). With P-C and ORO, Vv[steatosis, liver] was 4.86 ± 0.89% in the SC group and 25.21 ± 1.27% in the HF group (420% greater, P < 0.0001). With I-A and ORO, Vv[steatosis, liver] was 4.17 ± 0.85% in the SC group and 23.35 ± 1.58% in the HF group (460% greater, P < 0.0001). Correlations between Vv[steatosis, liver] and HT were strong and significant in all methods. In conclusion, all methods were appropriate and reproducible. In P-C and H-E, there is a slight overestimation of steatosis in the HF animals in comparison to frozen sections and ORO; in frozen sections, differences between P-C and I-A are insignificant.

Adiponectin activation of AMPK disrupts leptin-mediated hepatic fibrosis via suppressors of cytokine signaling (SOCS-3)

Adiponectin is an adipocytokine that was recently shown to be anti-fibrogenic in hepatic fibrosis. Leptin, on the other hand, promotes hepatic fibrosis. The purpose of the present study was to elucidate a mechanism (or mechanisms) whereby adiponectin dampens leptin signaling in activated hepatic stellate cells (HSCs), and prevents excess extracellular matrix production. Activated HSCs, between passages 2 and 5, were cultured and exposed to recombinant human adiponectin and recombinant leptin. Immunoblot analysis for SOCS-3, TIMP-1, and the phosphorylated species of Stat3 and adenosine monophosphate-activated protein kinase (AMPK) were conducted. We also examined MMP-1 activity by immunosorbant fluorimetric analysis. In HSCs, adiponectin-induced phosphorylation of AMPK, and subsequently suppressed leptin-mediated Stat3 phosphorylation and SOCS-3 induction. Adiponectin also blocked leptin-stimulated secretion of TIMP-1, and significantly increased MMP-1 activity, in vitro. To extend this study, we treated adiponectin knockout mice (Ad-/-) daily with 5 mg/kg recombinant leptin and/or carbon tetrachloride (2 ml/kg) for 6 weeks. Post-necropsy analysis was performed to examine for inflammation, and histological changes in the Ad-/- and wild-type mice. There was no significant difference in inflammation, or aminotransferases, between mice receiving carbon tetrachloride and leptin versus carbon tetrachloride alone. As anticipated, the combination of leptin and CCl(4) enhanced hepatic fibrosis in both wild-type and Ad-/- mice, as estimated by amount of collagen in injured livers, but wild-type mice had significantly higher levels of SOCS-3 and significantly lower levels of TIMP-1 mRNA and protein than did adiponectin KO mice exposed to both CCl(4) and leptin. We therefore conclude that the protective effects of adiponectin against liver fibrosis require AMPK activation, and may occur through inhibition of the Jak-Stat signal transduction pathway.

Adipocytokine involvement in hepatocellular carcinoma after sustained response to interferon for chronic hepatitis C

AIM

  Interferon (IFN) dramatically reduces the risk of hepatocellular carcinoma (HCC) after a sustained virological response (SVR) to chronic hepatitis C (CH-C). However, HCC still develops in some patients after SVR. To evaluate metabolic factors in patients with HCC occurring after SVR and to determine whether insulin resistance and adipocytokines were involved in this etiology.

METHODS

  We examined clinical and biochemical features, histological findings and serum levels of adipocytokine prior to IFN therapy and at the detection of HCC in nine patients who were diagnosed with HCC. As controls, 27 patients were included who showed SVR but had not been diagnosed with HCC for at least 5 years after SVR.

RESULTS

  Three of four patients who developed HCC within 5 years after SVR showed liver cirrhosis when HCC was diagnosed. Prior to IFN therapy, four of nine HCC patients were diagnosed as having type 2 diabetes mellitus. Serum levels of leptin and insulin, Homeostatic Model of Assessment of Insulin Resistance and body mass index (BMI) were significantly higher and serum adiponectin was significantly lower in HCC patients at the time of HCC detection than in control patients more than 5 years after SVR. Six HCC patients had increased BMI and one HCC patient had a decreased BMI during the observation period.

CONCLUSION

  Hepatic fibrosis may be tightly related to the emergence of HCC after SVR. Insulin resistance and adipocytokine disorders may be implicated in hepatocarcinogenesis after SVR, in part by promoting hepatic fibrosis.

The plasma lipidomic signature of nonalcoholic steatohepatitis

Specific alterations in hepatic lipid composition characterize the spectrum of nonalcoholic fatty liver disease (NAFLD), which extends from nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis (NASH). However, the plasma lipidome of NAFLD and whether NASH has a distinct plasma lipidomic signature are unknown. A comprehensive analysis of plasma lipids and eicosanoid metabolites quantified by mass spectrometry was performed in NAFL (n = 25) and NASH (n = 50) subjects and compared with lean normal controls (n = 50). The key findings include significantly increased total plasma monounsaturated fatty acids driven by palmitoleic (16:1 n7) and oleic (18:1 n9) acids content (P < 0.01 for both acids in both NAFL and NASH). The levels of palmitoleic acid, oleic acid, and palmitoleic acid to palmitic acid (16:0) ratio were significantly increased in NAFLD across multiple lipid classes. Linoleic acid (8:2n6) was decreased (P < 0.05), with a concomitant increase in gamma-linolenic (18:3n6) and dihomo gamma-linolenic (20:3n6) acids in both NAFL and NASH (P < 0.001 for most lipid classes). The docosahexanoic acid (22:6 n3) to docosapentenoic acid (22:5n3) ratio was significantly decreased within phosphatidylcholine (PC), and phosphatidylethanolamine (PE) pools, which was most marked in NASH subjects (P < 0.01 for PC and P < 0.001 for PE). The total plasmalogen levels were significantly decreased in NASH compared with controls (P < 0.05). A stepwise increase in lipoxygenase (LOX) metabolites 5(S)-hydroxyeicosatetraenoic acid (5-HETE), 8-HETE, and 15-HETE characterized progression from normal to NAFL to NASH. The level of 11-HETE, a nonenzymatic oxidation product of arachidonic (20:4) acid, was significantly increased in NASH only.

CONCLUSIONS

Although increased lipogenesis, desaturases, and LOX activities characterize NAFL and NASH, impaired peroxisomal polyunsaturated fatty acid (PUFA) metabolism and nonenzymatic oxidation is associated with progression to NASH.

Hepatitis C comorbidities affecting the course and response to therapy

Several studies have demonstrated that the outcome of chronic hepatitis C (CHC) infection is profoundly influenced by a variety of comorbidities. Many of these comorbidities have a significant influence on the response to antiviral therapy. These comorbidities negatively affect the course and outcome of liver disease, often reducing the chance of achieving a sustained virological response with PEGylated interferon and ribavirin treatments. Comorbidities affecting response to antiviral therapy reduce compliance and adherence to inadequate doses of therapy. The most important comorbidities affecting the course of CHC include hepatitis B virus coinfection, metabolic syndrome, and intestinal bacterial overgrowth. Comorbidities affecting the course and response to therapy include schistosomiasis, iron overload, alcohol abuse, and excessive smoking. Comorbidities affecting response to antiviral therapy include depression, anemia, cardiovascular disease, and renal failure.

Review article: nuclear receptors and liver disease--current understanding and new therapeutic implications

BACKGROUND

The important role of nuclear receptors and their contribution to liver function in both physiological and pathological conditions has come to attention in recent years and has advanced our understanding of several liver diseases. These findings led to the introduction of targeting nuclear receptors as treatment strategies for various liver diseases.

AIMS

To review the new insights brought by the study of nuclear receptors to our understanding of the molecular basis of various liver diseases, and to summarize some of the recent studies that evaluated the efficacy of targeting nuclear receptor as a new approach in treating liver diseases.

METHODS

Review of articles, using PubMed and article references.

RESULTS

Nuclear receptor ligands in patients with liver diseases have been associated with a variety of toxicities. Some clinical results have not met the expectations predicted from animal experiments. Mechanistic explanations at the molecular level are needed for preventing toxicity and improving outcomes from nuclear receptor ligands.

CONCLUSION

The use of various nuclear receptor ligands in liver diseases is a promising approach that can benefit many patients suffering from these devastating diseases. However, we are far from a full understanding of the molecular mechanisms by which these receptors work.

Could inflammatory markers help diagnose nonalcoholic steatohepatitis?

BACKGROUND

Nonalcoholic fatty liver disease describes a set of conditions that range from fatty liver to nonalcoholic steatohepatitis (NASH), and is considered the hepatic manifestation of metabolic syndrome. Obesity and insulin resistance are strongly associated with systemic markers of inflammation.

OBJECTIVE

Focusing on this aspect, we have attempted to find a noninvasive method that could likely assess the presence of NASH and help to decide the liver biopsy performance.

METHODS

Using histology as a gold standard to diagnose nonalcoholic fatty liver disease, we consecutively studied 43 patients with NASH and 40 with fatty liver, comparing their data with those of 48 healthy control participants. The outcomes evaluated were ultrasonographic spleen longitudinal diameter coupled with the splenic artery resistive index, serum IL-6 and vascular endothelial growth factor concentrations.

RESULTS

The NASH group had higher spleen longitudinal diameter values (P=0.0001) as well as significantly higher IL-6 and vascular endothelial growth factor concentrations than the other groups (P=0.0001). The optimal cut-off value for spleen longitudinal diameter that best discriminated NASH from fatty liver patients was 116 mm (specificity 95% and sensitivity 88%); the sensitivity and specificity of this parameter was better than both IL-6 and vascular endothelial growth factor in the same setting (area under the receiver operating characteristic curve 0.920 vs. 0.817 and 0.678). Splenic artery resistive index was similar between patients with NASH and those with fatty liver, but differed when compared with controls, P=0.0001.

CONCLUSIONS

IL-6 was highly specific in confirming the absence of NASH at normal values. In our series, normal values of spleen longitudinal diameter and IL-6 were strongly associated with fatty liver.

Steatohepatitis: Risk factors and impact on disease severity in human immunodeficiency virus/hepatitis C virus coinfection

Hepatic steatosis has been reported in human immunodeficiency virus (HIV)/hepatitis C virus (HCV) coinfection. However, the features of steatohepatitis, including cytologic ballooning and pericellular fibrosis, its risk factors, and the impact on disease severity in such patients are unknown. To assess this, we prospectively reviewed liver histology in consecutive coinfected patients to define the prevalence and severity of the features of steatohepatitis, its risk factors, and its impact on the severity of liver disease. A total of 222 subjects (74% male, mean age 45, 78% African American, 90% genotype 1) were studied. The mean body mass index (BMI) was 26, and 18% had a BMI >30. The prevalence of risk factors for steatosis were: diabetes (31%), hypertension (15%), dyslipidemia (8%), metabolic syndrome (9%), and alcohol abuse (21%). Steatosis was present in 23% and steatohepatitis was present in 17%. The steatosis was mild (5%-33%) in 19%, and moderate to severe (>33%) in 4%. Cytologic ballooning and pericellular fibrosis were present in 30% and 13%, respectively. The mean Ishak score was 6.9, and 33% had bridging fibrosis or cirrhosis. Both steatosis and cytologic ballooning were associated with BMI, metabolic syndrome, and insulin resistance, and presence of either was strongly associated with advanced fibrosis (P < 0.0001). By multiple logistic regressions, the following associations were identified: increased BMI, diabetes, and genotype 3 with steatosis; diabetes with cytologic ballooning; and longer duration of infection with steatohepatitis.

CONCLUSION

Steatosis and steatohepatitis are present in 23% and 30%, respectively, of patients with HIV/HCV coinfection, and both are associated with an increased risk of having advanced fibrosis. Although we did identify genotype 3, increased BMI, and diabetes as risk factors, we found no independent association with antiretroviral therapy.

Nonalcoholic fatty liver disease as a component of the metabolic syndrome

Nonalcoholic fatty liver disease (NAFLD) is an important cause of liver-related morbidity and mortality. The association between NAFLD and the metabolic syndrome is well established: the presence of the metabolic syndrome signifies advanced histology in NAFLD patients. Emerging data indicate that patients with NAFLD have a significantly higher prevalence of cardiovascular disease. This article reviews the definitions of the two syndromes, their association, and the cardiovascular risk conferred by both when they occur separately and together. This review also discusses management options for the syndromes, including treating the individual components of the metabolic syndrome in NAFLD patients.

Use of insulin sensitizers in NASH

This article briefly discusses nonalcoholic fatty liver disease (NAFLD) and its association with the metabolic syndrome, its pathogenesis and natural history. It then presents a detailed discussion on the efficacy and safety of different insulin sensitizers in patients who have NASH.

A lipidomic analysis of nonalcoholic fatty liver disease

The spectrum of nonalcoholic fatty liver disease (NAFLD) includes a nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). The specific types and amounts of lipids that accumulate in NAFLD are not fully defined. The free fatty acid (FFA), diacylglycerol (DAG), triacylglycerol (TAG), free cholesterol (FC), cholesterol ester, and phospholipid contents in normal livers were quantified and compared to those of NAFL and NASH, and the distribution of fatty acids within these classes was compared across these groups. Hepatic lipids were quantified by capillary gas chromatography. The mean (nmol/g of tissue) DAG (normal/NAFL/NASH: 1922 versus 4947 versus 3304) and TAG (13,609 versus 128,585 versus 104,036) increased significantly in NAFLD, but FFA remained unaltered (5533 versus 5929 versus 6115). There was a stepwise increase in the mean TAG/DAG ratio from normal livers to NAFL to NASH (7 versus 26 versus 31, P < 0.001). There was also a similar stepwise increment in hepatic FC (7539 versus 10,383 versus 12,863, P < 0.05 for NASH). The total phosphatidylcholine (PC) decreased in both NAFL and NASH. The FC/PC ratio increased progressively (0.34 versus 0.69 versus 0.71, P < 0.008 for both). Although the levels for linoleic acid (18:2n-6) and alpha-linolenic acid (18:3n-3) remained unaltered, there was a decrease in arachidonic acid (20:4n-6) in FFA, TAG, and PC (P < 0.05 for all) in NASH. Eicosapentanoic acid (20:5n-3) and docosahexanoic acid (22:6n-3) were decreased in TAG in NASH. The n-6:n-3 FFA ratio increased in NASH (P < 0.05).

CONCLUSIONS

NAFLD is associated with numerous changes in the lipid composition of the liver. The potential implications are discussed.

Predictors of cirrhosis in Hispanic patients with nonalcoholic steatohepatitis

It is estimated that 43% of patients with nonalcoholic steatohepatitis (NASH) will progress to liver fibrosis or cirrhosis. Although NASH is more common in Hispanics, most studies have been conducted on Caucasians, and there is scarce information regarding ethnic differences in this disease. The aim of this study was to identify the independent predictors of cirrhosis in Hispanic patients with NASH. A retrospective case-control study was conducted on 80 patients with biopsy-proven NASH. Forty-two were Hispanic (study group) and 38 were Caucasians controlled for age and BMI (control group). Clinical, biochemical, and histologic features were analyzed for correlation with cirrhosis. There were no significant differences in demographic features between the two groups. In multivariate analysis, independent predictors of cirrhosis among Hispanic patients were age (OR, 1.07; 95% CI, 1.01-1.14) and AST/ALT ratio (OR, 10.56; 95% CI; 2.46-45.29), while independent predictors among non-Hispanic patients were age (OR, 1.085; 95% CI, 1.0-1.186), and diabetes mellitus (OR, 6.46; 95% CI, 1.19-35.07). In patients with NASH, predictors of cirrhosis varied according to ethnic background. Age was an independent predictor in both groups, however, AST/ALT ratio was found to be an independent predictor of cirrhosis only in Hispanic patients, and diabetes mellitus only in non-Hispanic patients.

Glycogenic hepatopathy: an underrecognized hepatic complication of diabetes mellitus

Reported are the clinical and pathologic features of glycogenic hepatopathy, a pathologic overloading of hepatocytes with glycogen that is associated with poorly controlled diabetes mellitus. Fourteen cases were studied by stains, including hematoxylin and eosin, trichrome, periodic acid-Schiff, and periodic acid-Schiff with diastase. Ultrastructural analysis was performed in 2 cases. Medical records were reviewed for clinical presentations, laboratory findings, and clinical outcomes. The individuals ranged from 8 to 25 years of age. All had type I diabetes mellitus with poor glycemic control. The clinical presentations included hepatomegaly, abdominal pain, and elevated transaminases (range, 50-1600 IU/L). The transaminases were dramatically elevated in 3 cases to greater than 10 times the upper limit of normal. All biopsies showed diffusely pale staining hepatocytes on hematoxylin and eosin stains, with excessive glycogen accumulation demonstrated by periodic acid-Schiff stains. Ultrastructural examination revealed marked glycogen accumulation in the cytoplasm and nuclei. Most cases showed no evidence for fatty liver disease: steatosis was absent in 12 of 14 cases, simple steatosis was seen in 1 of 14 cases, and mild steatohepatitis was present in 1 of 14 cases. Mallory hyaline was absent in all cases, acidophil bodies were only rarely seen, and inflammation was absent or minimally present. Fibrosis was typically absent, with only 2 cases demonstrating focal mild fibrosis. Three patients had adequate follow-up and demonstrated improvement of liver enzyme levels with control of blood glucose. We conclude that glycogenic hepatopathy can cause hepatomegaly and significant transaminase elevations in individuals with type I diabetes mellitus. The pathology is distinct from steatohepatitis.

Review article: Drug therapy for non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease represents a spectrum of liver diseases, characterized mainly by macrovesicular steatosis in the absence of significant alcohol ingestion. Non-alcoholic fatty liver disease includes both non-alcoholic fatty liver and non-alcoholic steatohepatitis. Non-alcoholic steatohepatitis once considered a benign process is now known to lead to progressive fibrosis and cirrhosis. Histologically indistinguishable from alcoholic liver disease, the exact aetiology of non-alcoholic fatty liver disease remains unknown, but the fundamental pathophysiological process appears to be insulin resistance and oxidative stress related to the metabolic syndrome. Therapy has focused on risk factors, weight reduction and pharmacological intervention. Promising pharmacological treatments have been demonstrated with antioxidants, insulin sensitizers, hepatoprotectants and lipid-lowering agents. However, without larger randomized studies, no pharmacological treatments can be recommended at this time.

Mechanisms of Disease: pathogenesis of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is associated with the metabolic syndrome. The metabolic syndrome is characterized by insulin resistance, which is produced by a complex interaction between genetic factors, macronutrient intake and lifestyle that alters the cytokine profile, cell biology and biochemical milieu of the liver, adipose tissue and striated muscle. The resultant disequilibrium in lipid homeostasis causes triglycerides to accumulate in the liver. An increase in oxidative stress, due to the generation of reactive oxygen species as a result of mitochondrial abnormalities and induction of the cytochrome P-450 system could be one mechanism by which the nonalcoholic fatty liver develops into nonalcoholic steatohepatitis. The pathogenesis of cytologic ballooning and Mallory body formation and their role in NAFLD remain to be defined. In addition, inflammation and fibrosis are likely to be secondary to hepatocyte injury and death.

Review article: non-alcoholic fatty liver disease and hepatitis C--risk factors and clinical implications

Hepatitis C and non-alcoholic fatty liver disease (NAFLD) are the two most common liver diseases in the Western hemisphere. It is therefore natural that these conditions often co-exist in the same individual. Hepatitis C, especially genotype 3, is often associated with hepatic steatosis. In subjects with genotype 3 infection, a sustained virologic response to treatment is associated with improvement in hepatic steatosis. The diagnosis of NAFLD in a subject with hepatitis C infection is based on the presence of hepatic steatosis. Most investigators require the presence of at least grade II steatosis to warrant a diagnosis of concomitant NAFLD because the significance of minimal steatosis is uncertain. The presence of steatohepatitis is surmised by the additional presence of Mallory bodies, cytologic ballooning and pericellular fibrosis. It is of paramount importance to exclude alcohol as a cause of these histologic findings in this population before a diagnosis of NAFLD is made. The presence of NAFLD in subjects with hepatitis C genotype 1 infection is most strongly associated with the presence of the metabolic syndrome and insulin resistance. The degree of hepatic steatosis correlates with the degree of hepatic fibrosis and the presence of concomitant steatosis is associated with more advanced fibrosis. The presence of cytologic ballooning confers an additional risk for increased fibrosis. Insulin resistance and hyperinsulinemia have been associated with increased collagen production by hepatic stellate cells. Subjects with hepatitis C and NAFLD are more likely to be virologic nonresponders following anti-HCV therapy. The value of treating insulin resistance and NAFLD prior to antiviral therapy remains to be experimentally verified.

Reduced hepatic extraction of palmitate in steatosis correlated to lower level of liver fatty acid binding protein

Nonalcoholic fatty liver disease is the most common of all liver diseases. The hepatic disposition [(3)H]palmitate and its low-molecular-weight metabolites in perfused normal and steatotic rat liver were studied using the multiple indicator dilution technique and a physiologically based slow diffusion/bound pharmacokinetic model. The steatotic rat model was established by administration of 17 alpha-ethynylestradiol to female Wistar rats. Serum biochemistry markers and histology of treated and normal animals were assessed and indicated the presence of steatosis in the treatment group. The steatotic group showed a significantly higher alanine aminotransferase-to-aspartate aminotransferase ratio, lower levels of liver fatty acid binding protein and cytochrome P-450, as well as microvesicular steatosis with an enlargement of sinusoidal space. Hepatic extraction for unchanged [(3)H]palmitate and production of low-molecular-weight metabolites were found to be significantly decreased in steatotic animals. Pharmacokinetic analysis suggested that the reduced extraction and sequestration for palmitate and its metabolites was mainly attributed to a reduction in liver fatty acid binding protein in steatosis.

Evaluation and management of non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease represents a spectrum of liver diseases which occurs in the absence of alcohol consumption in amounts considered injurious to the liver. Non-alcoholic fatty liver disease includes both non-alcoholic fatty liver and non-alcoholic steatohepatitis. We present an integrated approach that utilizes both clinical and laboratory studies to diagnose and manage a patient with suspected non-alcoholic steatohepatitis. The goals of treatment include (1) correction of the underlying risk factors, (2) avoidance of factors that promote progression of liver disease, and (3) specific treatment of non-alcoholic steatohepatitis.

Leptin as a novel profibrogenic cytokine in hepatic stellate cells: mitogenesis and inhibition of apoptosis mediated by extracellular regulated kinase (Erk) and Akt phosphorylation

A key feature in the molecular pathogenesis of liver fibrosis requires maintenance of the activated hepatic stellate cell (HSC) phenotype by both proliferation and inhibition of apoptosis. We provide evidence that leptin is a potent HSC mitogen and dramatically inhibits stellate cell apoptosis. Leptin proved to be as potent an HSC mitogen as platelet-derived growth factor (PDGF) as assessed by bromodeoxyuridine (BrdU) incorporation in isolated primary HSCs; data using fluorescent propidium iodide (PI) uptake revealed that leptin, like PDGF, increased HSC populations in the S- and G2/M-phases of the cell cycle. Leptin resulted in a robust increase in cyclin D1 expression. Using the chemical inhibitor of Janus kinase 2 (Jak2) activity, AG 490, and overexpression of the suppressor of cytokine signaling 3 (SOCS-3), we show that blockade of leptin receptor (Ob-Rb) phosphorylation blocks leptin-induced HSC proliferation. Leptin-associated phosphorylation of both extracellular regulated kinase (p44/p42, Erk) and Akt is also prohibited. Further, the PI-3 kinase inhibitor LY294002 and MAPK inhibitor PD98059 were found to significantly reduce leptin-induced HSC proliferation, thereby indicating that leptin induced HSC proliferation is Akt- and Erk-dependent. Akt was also protective against HSC apoptosis. Leptin abolished both cycloheximide-induced and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis, demonstrated by reduced caspase-3 activity, HSC-TUNEL staining, and DNA fragmentation. We conclude that leptin acts as a direct hepatic stellate cell survival agonist. Importantly, we have demonstrated that leptin-induced HSC proliferation and survival by Ob-Rb phosphorylation are both Erk- and Akt-dependent.

Obesity, insulin resistance, and other clinicopathological correlates of pediatric nonalcoholic fatty liver disease

OBJECTIVE

To describe the clinical characteristics of nonalcoholic fatty liver disease (NAFLD) in children, including insulin resistance, and to test for correlation with liver pathology.

STUDY DESIGN

A retrospective review of children with biopsy-proven NAFLD at Children's Hospital San Diego from 1999 to 2002. Liver biopsy specimens were independently reviewed by two pathologists.

RESULTS

Children with NAFLD (n=43) were mostly male (70%), Hispanic American (53%) and obese (88%). The criteria for insulin resistance were met by 95% of subjects. Steatosis was predicted by the combination of quantitative insulin sensitivity check index, age, and ethnicity (P<.0001). Portal inflammation was predicted by the combination of ALT and fasting insulin (P=.0009). Perisinusoidal fibrosis was predicted by the combination of AST, fasting insulin, and BMI Z score (P<.0001). Portal fibrosis was predicted by the combination of right upper quadrant pain and homeostasis model assessment of insulin resistance (P=.0028).

CONCLUSIONS

We identified significant predictors of liver pathology in children with NAFLD. Children being evaluated for NAFLD should be screened for insulin resistance, which is nearly universal and correlates with liver histology.

Nonalcoholic fatty liver disease in patients with hepatitis C is associated with features of the metabolic syndrome

OBJECTIVES

The objectives of this study were to determine the following: 1) whether chronic hepatitis C virus (HCV) infection was specifically associated with nonalcoholic fatty liver disease (NAFLD); 2) the factors associated with NAFLD in patients with HCV; and 3) the clinical and histological spectrum of NAFLD occurring together with HCV.

METHODS

A retrospective analysis of 3826 biopsies was performed to compare the prevalence of NAFLD in those with HCV versus that in other liver diseases, e.g., hepatitis B, primary biliary cirrhosis, and alpha(1)-antitrypsin deficiency. Patients with HCV and NAFLD were also compared with an age- and gender-matched control group with HCV and <5% hepatic steatosis.

RESULTS

The prevalence of NAFLD in patients with HCV was similar to that in hepatitis B, primary biliary cirrhosis, or alpha(1)-antitrypsin deficiency. The risk of having NAFLD in patients with HCV correlated with body weight (r = 0.7, p < 0.02). Compared with a control group with HCV alone (n = 75), patients with HCV and NAFLD (n = 69) were likely to be heavier (mean BMI 27 vs 30, p < 0.003), diabetic (eight vs 21, p < 0.005), hypertensive (14 vs 25, p < 0.05), and hypertriglyceridemic (15 vs 33, p < 0.05). The HCV viral load, genotype distribution, liver enzymes, liver functions, and ferritin levels were comparable across the study groups. Those with HCV and NAFLD were more likely to have advanced fibrosis (bridging fibrosis or cirrhosis) (26% vs 53%, p < 0.03). Weight, diabetes, and cytological ballooning were independent predictors of advanced fibrosis in those with HCV and NAFLD.

CONCLUSIONS

The presence of NAFLD in patients with HCV is strongly associated with features of the metabolic syndrome and is a risk factor for advanced fibrosis. Advanced fibrosis in such patients is related to weight, presence of diabetes, and presence and degree of cytological ballooning.

Incidence of idiopathic acute liver failure and hospitalized liver injury in patients treated with troglitazone

OBJECTIVE

Troglitazone, a thiazolidinedione antidiabetic agent, was withdrawn from the U.S. market in March, 2000, after 94 cases of acute liver failure (ALF) were reported with its use. Based on a literature review, the estimated background rate of hospitalization for idiopathic acute liver injury is 22 per million person-years and for idiopathic ALF, less than 1 per million person-years. This study was conducted to estimate the incidence rates of hospitalized idiopathic acute liver injury and ALF among troglitazone-treated patients.

METHODS

An observational retrospective inception cohort of patients treated with troglitazone was assembled using claims data from a large multistate health care organization. Patients with at least 90 days of health plan enrollment before their first troglitazone prescription between April, 1997 and December, 1998 were enrolled. Hospitalized cases of potential troglitazone-induced acute liver injury or ALF were identified from claims data based on International Classification of Diseases, 9th Revision, coding. Primary medical records were reviewed for case validation, and incidence rates of acute liver injury were calculated using person-years of troglitazone exposure as the denominator.

RESULTS

A total of 7568 patients contributed 4020 person-years of troglitazone exposure. Of these, five were hospitalized with acute liver injury attributed to the drug and not explained by other causes. Incidence rates (95% CI) per million person-years of acute idiopathic liver injury were as follows: hospitalization (n = 5), 1244 (404, 2900); hospitalized jaundice (n = 4), 995 (271, 2546); and ALF (n = 1), 240 (6.3, 1385).

CONCLUSIONS

Troglitazone use was associated with a marked increase in risk of hospitalized acute idiopathic liver injury and ALF.