Liver Damage In Nonalcoholic Fatty Liver Disease Research Articles

Study of Plasma Pentraxin Levels as a Novel Marker versus Liver Stiffness for Nonalcoholic Steatohepatitis (NASH) in Egyptian Patients

Abstract Background Nonalcoholic fatty liver disease (NAFLD) includes a variety of histopathological findings ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) which can only be differentiated by liver biopsy. There is yet no unique biomarker found to discriminate NASH from simple steatosis. We aimed to investigate the relationship of plasma pentraxin 3 (PTX3) and liver elasticity measured by fibroscan both with the degree of liver damage in NAFLD. Methods Plasma PTX3 levels & fibroscan measurements were estimated in 60 patients with NAFLD (30 with NASH, 30 with non-NASH) and 20 controls Results PTX3 levels were found significantly higher in the NAFLD group than in the control group (3.59 ± 1.77 vs. 1.16 + –0.29 ng/mL, P < 0.001), and in NASH subgroup than non-NASH subgroup (4.97 + –1.36 vs. 21 + –.75 ng/mL, P = 0.001). To discriminate NASH from non-NASH PTX3 had 96.67% sensitivity and 93.33% specificity at the cutoff value of 3.1 ng/mL. Plasma PTX3 levels showed no significant correlation with NAFLD activity score, fibrosis stage and steatosis. Conclusion This study demonstrated markedly higher PTX3 levels in NAFLD patients compared with controls, and in NASH patients compared with non-NASH ones and no correlation wih fibroscan stages. Thus, in this cohort we showed that plasma PTX3 may be a promising biomarker for the presence of NASH.

Analysis of machine learning based integration to identify the crosslink between inflammation and immune response in non-alcoholic fatty liver disease through bioinformatic analysis

BackgroundThe prevalence of nonalcoholic fatty liver disease (NAFLD) is a major form of chronic liver disease. This study aimed to scrutinize the diagnostic biomarkers of NAFLD and their correlation with the immune microenvironment through bioinformatic analysis. MethodsTo identify genes associated with nonalcoholic fatty liver disease (NAFLD), we obtained microarray datasets (GSE63067 and GSE89632) from the Gene Expression Omnibus (GEO) database. Machine learning techniques such as Support Vector Machine (SVM), Least Absolute Shrinkage and Selection Operator (LASSO) and Random Forest (RF) were used to identify key genes. We performed gene ontology analysis to identify the driver pathways of NAFLD. External datasets (merging GSE48452, GSE66676 and GSE135251) were used to validate the identified genes and confirm protein levels by Western blotting. The CIBERSORT algorithm and immune-related techniques, such as ssGSEA, were used to assess the level of infiltration of different immune cell types and their functions. Finally, Spearman's analysis confirmed the relationship between pivotal genes and immune cells. ResultsHub genes (BBOX1, FOSB, NR4A2, RAB26 and SOCS2) were identified as potential biomarkers. This study demonstrates that these hub genes are significantly dysregulated in NAFLD, suggesting that they may be useful as diagnostic indicators and possible targets for treatment. Also covered are their possible effects on inflammation, immune cell activation, and liver damage in NAFLD. A better understanding of the intricate relationship between metabolic inefficiency, immunological response, and liver pathology in NAFLD may be gained from this work, which can lead to the development of new diagnostic tools and clinical treatments. ConclusionThe current study identified BBOX1, FOSB, NR4A2, RAB26 and SOCS2 as important diagnostic biomarkers for NAFLD. The study highlights the important function of immune cell infiltration in developing NAFLD. Their findings provide valuable molecular biological insights into the development of NAFLD and may lead to novel therapeutic strategies for treating this disease.

Navigating the Link Between Non-alcoholic Fatty Liver Disease/Non-alcoholic Steatohepatitis and Cardiometabolic Syndrome.

The global prevalence of non-alcoholic fatty liver disease (NAFLD) is nearly 25% and is increasing rapidly. The spectrum of liver damage in NAFLD ranges from simple steatosis to non-alcoholic steatohepatitis, characterised by the presence of lobular inflammation and hepatocyte ballooning degeneration, with or without fibrosis, which can further develop into cirrhosis and hepatocellular carcinoma. Not only is NAFLD a progressive liver disease, but numerous pieces of evidence also point to extrahepatic consequences. Accumulating evidence suggests that patients with NAFLD are also at increased risk of cardiovascular disease (CVD); in fact, CVDs are the most common cause of mortality in patients with NAFLD. Obesity, type 2 diabetes and higher levels of LDL are common risk factors in both NAFLD and CVD; however, how NAFLD affects the development and progression of CVD remains elusive. In this review, we comprehensively summarise current data on the key extrahepatic manifestations of NAFLD, emphasising the possible link between NAFLD and CVD, including the role of proprotein convertase substilisin/kenin type 9, extracellular vesicles, microbiota, and genetic factors.

Non Alcoholic Fatty Liver Disease (NAFLD) – An Emerging Challenge

A rapidly emerging cause of Chronic Liver Disease (CLD) is Non-alcoholic Fatty Liver Disease (NAFLD). In the West, the prevalence of NAFLD is as high as 30% and it is postulated that it may affect one-third of the population by 2030 [1]. Various studies have shown that the prevalence of NAFLD in Pakistan ranges from 14% to 47% [2]. The spectrum of liver damage in NAFLD is wide-ranging and essentially involves non-alcoholic causes of fat accumulation in the cells of the liver. This can also occur in other conditions where there is more than 5% steatosis. These conditions include chronic liver disease (CLD) caused by drugs (such as Methotrexate, Amiodarone, Tamoxifen etc.) or viruses (such as HCV), exposure to environmental toxins, malnutrition, hemochromatosis, Wilson’s disease, and any autoimmune disease triggering 5% steatosis [3]. There is a strong association of NAFLD with obesity (in more than 40% of patients) [4], hypertriglyceridemia (in 20% or more), diabetes mellitus (in 20% or more), and insulin resistance – all components of the metabolic syndrome [5]. Over the last two decades, rising trends of DM, obesity and insulin resistance have gone hand in hand with increasing prevalence of NAFLD [6]. Pakistan has a 17.1% incidence of Type-2 diabetes and a 14% incidence of NAFLD. There is a 32% incidence of NAFLD in Pakistani type 2 diabetics [7]. The National Health Survey of Pakistan conducted way back in 2006 depicted an incidence of obesity in 25% of the Pakistani population, and since then, numbers have continued to rise.

Non-alcoholic fatty liver disease and COVID-19: Harmless companions or disease intensifier?

The pandemics of coronavirus disease 2019 (COVID-19) and non-alcoholic fatty liver disease (NAFLD) coexist. Elevated liver function tests are frequent in COVID-19 and may influence liver damage in NAFLD, while preexisting liver damage from NAFLD may influence the course of COVID-19. However, the prognostic relevance of this interaction, though, is unclear. Obesity is a risk factor for the presence of NAFLD as well as a severe course of COVID-19. Cohort studies reveal conflicting results regarding the influence of NAFLD presence on COVID-19 illness severity. Striking molecular similarities of cytokine pathways in both diseases, including postacute sequelae of COVID-19, suggest common pathways for chronic low-activity inflammation. This review will summarize existing data regarding the interaction of both diseases and discuss possible mechanisms of the influence of one disease on the other.

The hepatic integrated stress response suppresses the somatotroph axis to control liver damage in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) can be ameliorated by calorie restriction, which leads to the suppressed somatotroph axis. Paradoxically, the suppressed somatotroph axis is associated with patients with NAFLD and is correlated with the severity of fibrosis. How the somatotroph axis becomes dysregulated and whether the repressed somatotroph axis impacts liver damage during the progression of NAFLD are unclear. Here, we identify a regulatory branch of the hepatic integrated stress response (ISR), which represses the somatotroph axis in hepatocytes through ATF3, resulting in enhanced cell survival and reduced cell proliferation. In mouse models of NAFLD, the ISR represses the somatotroph axis, leading to reduced apoptosis and inflammation but decreased hepatocyte proliferation and exacerbated fibrosis in the liver. NAD+ repletion reduces the ISR, rescues the dysregulated somatotroph axis, and alleviates NAFLD. These results establish that the hepatic ISR suppresses the somatotroph axis to control cell fate decisions and liver damage in NAFLD.

Imaging Mass Spectrometry Reveals Alterations in N-Linked Glycosylation That Are Associated With Histopathological Changes in Nonalcoholic Steatohepatitis in Mouse and Human

Nonalcoholic steatohepatitis (NASH) is the progressive form of nonalcoholic fatty liver disease (NAFLD) and is characterized by inflammation, hepatocyte injury, and fibrosis. Further, NASH is a risk factor for cirrhosis and hepatocellular carcinoma. Previous research demonstrated that serum N-glycan profiles can be altered in NASH patients. Here, we hypothesized that these N-glycan modifications may be associated with specific liver damage in NAFLD and NASH. To investigate the N-glycome profile in tissue, imaging mass spectrometry was used for a qualitative and quantitative in situ N-linked glycan analysis of mouse and human NAFLD/NASH tissue. A murine model was used to induce NAFLD and NASH through ad libitum feeding with either a high-fat diet or a Western diet, respectively. Mice fed a high-fat diet or Western diet developed inflammation, steatosis, and fibrosis, consistent with NAFLD/NASH phenotypes. Induction of NAFLD/NASH for 18 months using high caloric diets resulted in increased expression of mannose, complex/fucosylated, and hybrid N-glycan structures compared to control mouse livers. To validate the animal results, liver biopsy specimens from 51 human NAFLD/NASH patients representing the full range of NASH Clinical Research Network fibrosis stages were analyzed. Importantly, the same glycan alterations observed in mouse models were observed in human NASH biopsies and correlated with the degree of fibrosis. In addition, spatial glycan alterations were localized specifically to histopathological changes in tissue like fibrotic and fatty areas. We demonstrate that the use of standard staining’s combined with imaging mass spectrometry provide a full profile of the origin of N-glycan modifications within the tissue. These results indicate that the spatial distribution of abundances of released N-glycans correlate with regions of tissue steatosis associated with NAFLD/NASH.

Non-Alcoholic Fatty Liver Disease (NAFLD) in Patients with Psoriasis: A Review of the Hepatic Effects of Systemic Therapies.

There is increasing interest in the association between psoriasis and non-alcoholic fatty liver disease (NAFLD), which is a prevalent liver disease characterized by excessive fat storage and inflammation that can progress to fibrosis and cancer. Patients with psoriasis have a two-fold higher risk to develop NAFLD and a higher risk to progress to more severe liver disease. Psoriasis and NAFLD share common risk factors such as smoking, alcohol consumption, and the presence of metabolic syndrome and its component disorders. In addition, both psoriasis and NAFLD hinge upon a systemic low-grade inflammation that can lead to a vicious cycle of progressive liver damage in NAFLD as well as worsening of the underlying psoriasis. Other important shared pathophysiological pathways include peripheral insulin resistance and oxidative stress. NAFLD should receive clinical awareness as important comorbidity in psoriasis. In this review, we assess the recent literature on the epidemiological and pathophysiological relationship of psoriasis and NAFLD, discuss the clinical implications of NAFLD in psoriasis patients, and summarize the hepatotoxic and hepatoprotective potential of systemic psoriasis therapies.

The rs599839 A>G Variant Disentangles Cardiovascular Risk and Hepatocellular Carcinoma in NAFLD Patients.

Simple SummaryDyslipidemia is a hallmark of nonalcoholic fatty liver disease (NAFLD) and the rs599839 variant in the CELSR2-PSRC1-SORT1 genetic cluster, has been associated with a protection against cardiovascular events. Here, we revealed a novel link between the rs599839 variant and hepatocellular carcinoma (HCC) whose onset in the context of NAFLD is rapidly increasing. We found that the rs599839 variant disentangled the risk of HCC from that of cardiovascular abnormalities by modulating SORT1 and PSRC1 expressions. The latter emerged as a potential modifier of liver carcinogenesis.Background and Aims: Dyslipidemia and cardiovascular diseases (CVD) are comorbidities of nonalcoholic fatty liver disease (NAFLD), which ranges from steatosis to hepatocellular carcinoma (HCC). The rs599839 A>G variant, in the CELSR2-PSRC1-SORT1 gene cluster, has been associated CVD, but its impact on metabolic traits and on the severity liver damage in NAFLD has not been investigated yet. Methods: We evaluated the effect of the rs599839 variant in 1426 NAFLD patients (Overall cohort) of whom 131 had HCC (NAFLD-HCC), in 500,000 individuals from the UK Biobank Cohort (UKBBC), and in 366 HCC samples from The Cancer Genome Atlas (TCGA). Hepatic PSRC1, SORT1 and CELSR2 expressions were evaluated by RNAseq (n = 125). Results: The rs599839 variant was associated with reduced circulating LDL, carotid intima-media thickness, carotid plaques and hypertension (p < 0.05) in NAFLD patients and with protection against dyslipidemia in UKBBC. The minor G allele was associated with higher risk of HCC, independently of fibrosis severity (odds ratio (OR): 5.62; 95% c.i. 1.77–17.84, p = 0.003), poor prognosis and advanced tumor stage (p < 0.05) in the overall cohort. Hepatic PSRC1, SORT1 and CELSR2 expressions were increased in NAFLD patients carrying the rs599839 variant (p < 0.0001). SORT1 mRNA levels negatively correlated with circulating lipids and with those of genes involved in lipoprotein turnover (p < 0.0001). Conversely, PSRC1 expression was positively related to that of genes implicated in cell proliferation (p < 0.0001). In TCGA, PSRC1 over-expression promoted more aggressive HCC development (p < 0.05). Conclusions: In sum, the rs599839 A>G variant is associated with protection against dyslipidemia and CVD in NAFLD patients, but as one it might promote HCC development by modulating SORT1 and PSRC1 expressions which impact on lipid metabolism and cell proliferation, respectively.

IL-18 but Not IL-1 Signaling Is Pivotal for the Initiation of Liver Injury in Murine Non-Alcoholic Fatty Liver Disease.

Non-alcoholic fatty liver disease (NAFLD) is rising in prevalence, and a better pathophysiologic understanding of the transition to its inflammatory phenotype (NASH) is key to the development of effective therapies. To evaluate the contribution of the NLRP3 inflammasome and its downstream effectors IL-1 and IL-18 in this process, we applied the true-to-life “American lifestyle-induced obesity syndrome” (ALiOS) diet mouse model. Development of obesity, fatty liver and liver damage was investigated in mice fed for 24 weeks according to the ALiOS protocol. Lipidomic changes in mouse livers were compared to human NAFLD samples. Receptor knockout mice for IL-1 and IL-18 were used to dissect the impact of downstream signals of inflammasome activity on the development of NAFLD. The ALiOS diet induced obesity and liver steatosis. The lipidomic changes closely mimicked changes in human NAFLD. A pro-inflammatory gene expression pattern in liver tissue and increased serum liver transaminases indicated early liver damage in the absence of histological evidence of NASH. Mechanistically, Il-18r−/−- but not Il-1r−/− mice were protected from early liver damage, possibly due to silencing of the pro-inflammatory gene expression pattern. Our study identified NLRP3 activation and IL-18R-dependent signaling as potential modulators of early liver damage in NAFLD, preceding development of histologic NASH.

β-Klotho gene variation is associated with liver damage in children with NAFLD

Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in adults and children. Along with obesity, diabetes and insulin resistance, genetic factors strongly impact on NAFLD development and progression. Dysregulated bile acid metabolism and the fibroblast growth factor 19 (FGF19) pathway play a pivotal role in NAFLD pathogenesis. However, the mechanism through which the FGF19 receptor system is associated with liver damage in NAFLD remains to be defined. We evaluated the impact of the rs17618244 G>A β-Klotho (KLB) variant on liver damage in 249 pediatric patients with biopsy-proven NAFLD and the association of this variant with the expression of hepatic and soluble KLB. In vitro models were established to investigate the role of the KLB mutant. The KLB rs17618244 variant was associated with an increased risk of ballooning and lobular inflammation. KLB plasma levels were lower in carriers of the rs17618244 minor A allele and were associated with lobular inflammation, ballooning and fibrosis. In HepG2 and Huh7 hepatoma cell lines, exposure to free fatty acids caused a severe reduction of intracellular and secreted KLB. Finally, KLB downregulation obtained by the expression of a KLB mutant in HepG2 and Huh7 cells induced intracellular lipid accumulation and upregulation of p62, ACOX1, ACSL1, IL-1β and TNF-α gene expression. In conclusion, we showed an association between the rs17618244 KLB variant, which leads to reduced KLB expression, and the severity of NAFLD in pediatric patients. We can speculate that the KLB protein may exert a protective role against lipotoxicity and inflammation in hepatocytes. Genetic and environmental factors strongly impact on the pathogenesis and progression of non-alcoholic fatty liver disease (NAFLD). The FGF19/FGFR4/KLB pathway plays a pivotal role in the pathogenesis of NAFLD. The aim of the study was to investigate the impact of a genetic variant in the KLB gene on the severity of liver disease. Our data suggest that the KLB protein plays a protective role against lipotoxicity and inflammation in hepatocytes.

Associations of Plasma CD36 and Body Fat Distribution.

CD36 is a class B scavenger-receptor involved in the uptake of fatty acids in liver and adipose tissue. It is unknown whether plasma CD36 levels are related to liver fat content or adipose tissue in the general population. We measured plasma CD36 from 575 participants of the community-based PopGen cohort who underwent MRI to quantify visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and liver signal intensity (LSI), a proxy for liver fat content. Nonalcoholic fatty liver disease (NAFLD) was defined as LSI ≥3.0 in the absence of high alcohol intake. The relations between plasma CD36 and body mass index (BMI), VAT, SAT, LSI, and NAFLD were evaluated via multivariable-adjusted linear and logistic regression analysis. Plasma CD36 concentrations were correlated with BMI (r = 0.11; P = 0.01), SAT (r = 0.16; P < 0.001), and VAT (r = 0.15, P < 0.001) but not with LSI (P = 0.44). In multivariable-adjusted regression models, mean BMI values rose across CD36 quartiles [quartile 1 (Q1), 27.8 kg/m2; Q4, 28.9 kg/m2; P-trend = 0.013). Similarly, VAT (Q1, 4.13 dm3; Q4, 4.71 dm3; P-trend < 0.001), and SAT (Q1, 7.61 dm3; Q4, 8.74 dm3; P-trend < 0.001) rose across CD36 quartiles. Plasma CD36 concentrations were unrelated to LSI (P-trend = 0.36) and NAFLD (P-trend = 0.64). Participants with NAFLD and elevated alanine aminotransferase (ALT), a marker for liver damage, had higher CD36 compared with participants with NAFLD and normal ALT. Higher plasma concentrations of CD36 were associated with greater general and abdominal adiposity but not with liver fat content or NAFLD in this community-based sample. However, plasma CD36 may reflect more severe liver damage in NAFLD.

Vitamin D Supplementation and Non-Alcoholic Fatty Liver Disease: Present and Future.

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic hepatic disease throughout the Western world and is recognized as the main cause of cryptogenic cirrhosis; however, the identification of an effective therapy for NAFLD is still a major challenge. Vitamin D deficiency is a wide-spread condition which reaches epidemic proportions in industrialized countries, mainly in relation to current lifestyle and limited dietary sources. Epidemiological studies point towards an association between hypovitaminosis D and the presence of NAFLD and steatohepatitis (NASH), independently of confounders such as obesity and insulin resistance. Furthermore, several pieces of experimental data have shown the anti-fibrotic, anti-inflammatory and insulin-sensitizing properties exerted by vitamin D on hepatic cells. However, results from trials evaluating the effects of oral vitamin D supplementation on liver damage in NAFLD and NASH are controversial. The aim of this review is to give an overview of the evidence currently available from clinical trials and to discuss possible shortcomings and new strategies to be considered in future investigations.

ER stress-mediated cell damage contributes to the release of EDA+ fibronectin from hepatocytes in nonalcoholic fatty liver disease.

Fibronectin containing extra domain A (EDA+ FN), a functional glycoprotein participating in several cellular processes, correlates with chronic liver disease. Herein, we aim to investigate the expression and secretion of EDA+ FN from hepatocytes in nonalcoholic fatty liver disease (NAFLD) and the underlying mechanisms. Circulating levels of EDA+ FN were determined by ELISA in clinical samples. Western blotting and flow cytometry were performed on L02 and HepG2 cell lines to analyze whether the levels of EDA+ FN were associated with endoplasmic reticulum (ER) stress-related cell death. Circulating levels of EDA+ FN in NAFLD patients were significantly higher than those in control subjects, and positively related with severity of ultrasonographic steatosis score. In cultured hepatocytes, palmitate up-regulated the expression of EDA+ FN in a dose-dependent manner. Conversely, when the cells were pretreated with 4-phenylbutyrate, a specific inhibitor of ER stress, up-regulation of EDA+ FN could be abrogated. Moreover, silencing CHOP by shRNA enhanced the release of EDA+ FN from hepatocytes following palmitate treatment, which was involved in ER stress-related cell damage. These findings suggest that the up-regulated level of EDA+ FN is associated with liver damage in NAFLD, and ER stress-mediated cell damage contributes to the release of EDA+ FN from hepatocytes.

Effects of Phlebotomy on Liver Enzymes and Histology of Patients with Nonalcoholic Fatty Liver Disease

Background:Nonalcoholic fatty liver disease (NAFLD), defined as excessive liver fat deposition and one of end-stage liver disease causes. Increased ferritin levels are associated with insulin resistance and a higher hepatic iron and fat content. Hyperferritinemia has been associated with severity of liver damage in NAFLD. The study aimed to evaluate the effects of phlebotomy on liver enzymes and histology in such patients.Materials and Methods:Thirty-two eligible patients who had NAFLD and after 6 months of lifestyle modification still had NAFLD, and whose ferritin serum was above 250 mg/dl, were enrolled in this clinical trial study. After written informed consent was obtained, each patient's blood serum was taken for aspartate transaminase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALK-P), complete blood count (CBC), total iron-binding capacity (TIBC), iron, and ferritin. Then the patients underwent liver biopsy. After that patients underwent phlebotomy, giving 350 cc blood monthly. Before every phlebotomy, hemoglobin and ferritin were checked. If they were in the goal range, phlebotomy was discontinued and the patient underwent liver biopsy. A serum sample was taken for testing at the beginning of the study. The results before and after phlebotomy were compared. The maximum duration of the study was 6 months.Results:Thirty-two patients (26 males and 6 females) were enrolled, and the mean average age was 33.7 ± 6.74 years. Phlebotomy improved liver enzymes and histology of liver significantly (P < 0.001) and induced reduction of ferritin.Conclusion:Phlebotomy is effective for the improvement of liver enzymes and histology in patients with NAFLD and hyperferritinemia.

Role of Serum Uric Acid and Ferritin in the Development and Progression of NAFLD.

Nonalcoholic fatty liver disease (NAFLD), tightly linked to the metabolic syndrome (MS), has emerged as a leading cause of chronic liver disease worldwide. Since it is potentially progressive towards non-alcoholic steatohepatitis (NASH) and hepatic fibrosis, up to cirrhosis and its associated complications, the need for predictive factors of NAFLD and of its advanced forms is mandatory. Despite the current “gold standard” for the assessment of liver damage in NAFLD being liver biopsy, in recent years, several non-invasive tools have been designed as alternatives to histology, of which fibroscan seems the most promising. Among the different serum markers considered, serum uric acid (SUA) and ferritin have emerged as possible predictors of severity of liver damage in NAFLD. In fact, as widely described in this review, they share common pathogenetic pathways and are both associated with hepatic steatosis and MS, thus suggesting a likely synergistic action. Nevertheless, the power of these serum markers seems to be too low if considered alone, suggesting that they should be included in a wider perspective together with other metabolic and biochemical parameters in order to predict liver damage.

Role of adipokines in the pathogenesis of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome. The increased prevalence of obesity, diabetes, hypertension, hypertriglyceridaemia and hypercholesterolemia are considered to be the potential causative factors for NAFLD. NAFLD is emerging as a major clinical problem worldwide. Recently much attention has been focused in India as the prevalence of obesity and diabetes is rising. NAFLD is responsible for unexplained raise in transaminases, and an important cause of cryptogenic cirrhosis and cryptogenic hepatocellular carcinoma in India. NAFLD is a spectrum of disease ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), potentially leading to fibrosis and cirrhosis. Studies have suggested that the adipokines are involved in the pathogenesis of NAFLD and its progression to NASH, through their metabolic and pro- or anti-inflammatory activity. Adipokines in particular tumor necrosis factor-α and interleukin-6 are believed to mediate the shift in pathology from steatosis to steatohepatitis. In addition, other adipokines such as adiponectin, leptin and resistin also play a crucial role in the development and progression of NAFLD through their metabolic and pro-or anti-inflammatory activity. This suggests that imbalance between pro-inflammatory and anti-inflammatory cytokines may have a role in the development of liver damage in NAFLD. Understanding the relationship between adipokines and NAFLD may play an important role in the early identification/diagnosis, treatment and also help in preventing disease progression.

Toll-like receptor-4 is involved in hepatic fibrogenesis in the course of non-alcoholic fatty liver disease

Toll-like receptor-4 (TLR4) is actively involved in liver in the response to injury from a variety of etiologies. Recently TLR4 expression by hepatic progenitor cells (HPC) and biliary epithelial cells has been associated to the progression of liver damage in chronic HCV-related hepatitis (1). HPC compartment activation in ductular reaction (DR) is a feature of progressive disease also in non-alcoholic fatty liver disease (NAFLD) (2). We aimed to investigate the association among TLR4 expression, HPC compartment activation and histopathologic features of fibrotic disease progression in NAFLD. Seventy-four patients who had undergone liver biopsy were included and immunohistochemistry for TLR4 was performed on hepatic tissue samples. CK-7 was used to evaluate HPC, bile ducts (BD)/ductules of DR and intermediate hepatocytes; α-smooth muscle actin was used to quantify the activation of hepatic stellate cells (HSC) and of portal/septal myofibroblasts (MF). HPC in BD/DR were responsible for the highest TLR4 intensity of staining. TLR4-positive HPC and BD/ DR correlated with fibrosis (p<0.01 and p<0.05), activity of MF (p<0.001 and p<0.05) and HSC (p<0.001 and p<0.001), portal and interface chronic inflammation (p<0.01 and p=0.01). The present study indicates the activation of the TLR4 expressing HPC compartment as important determinant of the progressive liver damage in NAFLD. TLR4 stimulation could represent one of the mechanisms directly linking the activation of HPC to inflammation and fibrosis in NAFLD.

Hedgehog pathway activation parallels histologic severity of injury and fibrosis in human nonalcoholic fatty liver disease

The Hedgehog (HH)-signaling pathway mediates several processes that are deregulated in patients with metabolic syndrome (e.g., fat mass regulation, vascular/endothelial remodeling, liver injury and repair, and carcinogenesis). The severity of nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome generally correlate. Therefore, we hypothesized that the level of HH-pathway activation would increase in parallel with the severity of liver damage in NAFLD. To assess potential correlations between known histologic and clinical predictors of advanced liver disease and HH-pathway activation, immunohistochemistry was performed on liver biopsies from a large, well-characterized cohort of NAFLD patients (n = 90) enrolled in the Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) Database 1 study. Increased HH activity (evidenced by accumulation of HH-ligand-producing cells and HH-responsive target cells) strongly correlated with portal inflammation, ballooning, and fibrosis stage (each P < 0.0001), supporting a relationship between HH-pathway activation and liver damage. Pathway activity also correlated significantly with markers of liver repair, including numbers of hepatic progenitors and myofibroblastic cells (both P < 0.03). In addition, various clinical parameters that have been linked to histologically advanced NAFLD, including increased patient age (P < 0.005), body mass index (P < 0.002), waist circumference (P < 0.0007), homeostatic model assessment of insulin resistance (P < 0.0001), and hypertension (P < 0.02), correlated with hepatic HH activity. In NAFLD patients, the level of hepatic HH-pathway activity is highly correlated with the severity of liver damage and with metabolic syndrome parameters that are known to be predictive of advanced liver disease. Hence, deregulation of the HH-signaling network may contribute to the pathogenesis and sequelae of liver damage that develops with metabolic syndrome.

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.