Alterations in lipid, carbohydrate and iron metabolism in patients with non-alcoholic steatohepatitis (NASH) and metabolic syndrome

Reactive oxygen species regulation by NCF1 governs ferroptosis susceptibility of Kupffer cells to MASH

Impaired self-renewal of Kupffer cells (KCs) leads to inflammation in metabolic dysfunction-associated steatohepatitis (MASH). Here, we identify neutrophil cytosolic factor 1 (NCF1) as a critical regulator of iron homeostasis in KCs. NCF1 is upregulated in liver macrophages and dendritic cells in humans with metabolic dysfunction-associated steatotic liver disease and in MASH mice. Macrophage NCF1, but not dendritic cell NCF1, triggers KC iron overload, ferroptosis, and monocyte-derived macrophage infiltration, thus aggravating MASH progression. Mechanistically, elevated oxidized phospholipids induced by macrophage NCF1 promote Toll-like receptor (TLR4)-dependent hepatocyte hepcidin production, leading to increased KC iron deposition and subsequent KC ferroptosis. Importantly, the human low-functional polymorphic variant NCF190H alleviates KC ferroptosis and MASH in mice. In conclusion, macrophage NCF1 impairs iron homeostasis in KCs by oxidizing phospholipids, triggering hepatocyte hepcidin release and KC ferroptosis in MASH, highlighting NCF1 as a therapeutic target for improving KC fate and limiting MASH progression.

IS HOMEOSTASIS MODEL ASSESSMENT FOR INSULIN RESISTANCE >2.5 A DISTINGUISHED CRITERIA FOR METABOLIC DYSFUNCTION-ASSOCIATED FATTY LIVER DISEASE IDENTIFICATION?

BACKGROUND

Insulin resistance (IR), assessed by different criteria, is an important factor in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). More recently with the characterization of this metabolic dysfunction-associated fatty liver disease (MAFLD), one of the proposed criteria for this diagnosis has been the determination of the homeostasis model assessment-insulin resistance (HOMA-IR).

OBJECTIVE

The purpose of this study was to evaluate the relationship of HOMA-IR>2.5 with clinical, metabolic, biochemical and histological data obtained in non-diabetic patients diagnosed with NAFLD by liver biopsy.

METHODS

Cross-sectional, retrospective study was carried out with data from 174 adult individuals of both genders with non-diabetics NAFLD, without obvious signs of portal hypertension. The body mass index (BMI) was classified according to the World Health Organization (1998), and the metabolic syndrome by the criteria of NCEP-ATP-III. Biochemical tests were evaluated using an automated method and insulinemia through immunofluorometric assay. Histological findings were classified according to Kleiner et al. (2005).

RESULTS

The mean age of the studied population was 53.6±11.2 years, with 60.3% being female. The average BMI was 30.3 kg/m2 and 75.9% of the patients had increased waist circumference. Among evaluated metabolic parameters, there was a higher prevalence of metabolic syndrome (MS) in patients with HOMA-IR>2.5, with no statistical difference in relation to BMI between studied groups. Values of liver enzymes and serum ferritin were significantly higher in patients with this marker of IR, who had a higher prevalence of non-alcoholic steatohepatitis (NASH) and advanced liver fibrosis. In the multivariate analysis, the clinical diagnosis of MS, hyperferritinemia and the presence of NASH in the liver biopsy were the factors independently associated with the presence of altered HOMA-IR.

CONCLUSION

HOMA-IR values >2.5 identify patients with NAFLD with distinct clinical and metabolic characteristics and with a greater potential for disease progression, which validates this parameter in the identification of patients with MAFLD.

Lean non-alcoholic fatty liver disease and associated metabolic disturbance: A Saudi Arabian cross-sectional study

Non-alcoholic liver disease (NAFLD) is a metabolic liver disease associated with visceral adiposity and insulin resistance. Recently, NAFLD has been described in lean individuals who additionally have impaired metabolic parameters similar to their non-lean counterparts. We aimed to explore this further in Saudi Arabia. From 2016 to 2019, we prospectively studied a group of newly diagnosed NAFLD patients at a tertiary hospital in Saudi Arabia. Patients were classified into three groups: lean (body mass index [BMI] <25), overweight (BMI ≥25 and <30), and obese (BMI ≥30). We made comparisons between these groups on basic clinical, demographic, and laboratory parameters. In total, 1753 patients were recruited and 1262 patients met the inclusion criteria. Altogether, 159 (12.6%), 365 (29%), and 737 (58.4%) patients were in the lean, overweight, and obese categories, respectively. Lean NAFLD patients were, on average, younger than those in the overweight group (mean 49.95 ± 15.3) and had a significantly higher high-density lipoprotein value (HDL) (mean 52.56 ± 16.27). Sex, hyperlipidemia, type 2 diabetes, and hypertension were significantly associated with BMI. Lean NAFLD patients displayed the features of metabolic syndrome including elevated glycosylated hemoglobin and abnormal lipid profile but had higher serum HDL. This is in contrast to the widely held belief that lean individuals have no dysmetabolic changes compared to overweight individuals. Recognition of this problem is essential so that lean NAFLD patients can be screened for metabolic changes and managed appropriately to prevent complications.

Long-term profile of serological biomarkers, hepatic inflammation, and fibrosis in a mouse model of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) can be typically classified into two subgroups: non-alcoholic fatty liver and non-alcoholic steatohepatitis. Mouse models of NAFLD are useful tools for understanding the pathogenesis and progression of NAFLD and for developing drugs for its treatment. Here, we investigated the time-dependent changes in serum lipids and biochemical markers of hepatic function, hepatic inflammation, and fibrosis in mice fed a normal diet (ND) or a NAFLD diet (choline deficient, L-amino acid-defined, high-fat diet; CDAHFD) for 12 weeks. CDAHFD-fed mice showed significantly reduced serum levels of total cholesterol, triglyceride, and high-density lipoprotein cholesterol throughout the treatment period compared with ND-fed mice. The changes in aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and total bilirubin showed an inverse U-shaped curve in the CDAHFD-fed mice. The serum alkaline phosphatase levels decreased in both ND- and CDAHFD-fed mice in a time-dependent manner. Furthermore, CDAHFD-fed mice showed a significant increase in the number of inflammatory foci and hepatic fibrosis at 6-12 weeks, although inflammatory foci and hepatic fibrogenesis were observable at relatively early stages as well (1-4 weeks). In conclusion, the long-term profile of serological biomarkers, hepatic inflammation, and fibrosis in CDAHFD-fed mice identified in this study may provide a better understanding of NAFLD pathogenesis.

The role of hepcidin and iron homeostasis in atherosclerosis

Atherosclerotic cardiovascular disease is a major burden on global health and a leading cause of death worldwide. The pathophysiology of this chronic disease is complex, involving inflammation, lipoprotein oxidation and accumulation, plaque formation, and calcification. In 1981, Dr. Jerome Sullivan formulated the 'Iron Hypothesis', suggesting that higher levels of stored iron promote cardiovascular diseases, whereas iron deficiency may have an atheroprotective effect. This hypothesis has stimulated research focused on clarifying the role of iron in the development of atherosclerosis. However, preclinical and clinical studies have produced contradictory results and the observation that patients with hemochromatosis do not appear to have an increased risk of atherosclerosis seemed incongruous with Sullivan's initial hypothesis. The 'paradox' of systemic iron overload not being accompanied by an increased risk for atherosclerosis led to a refinement of the iron hypothesis focusing on intracellular macrophage iron. More recent in vitro and animal studies have elucidated the complex signaling pathways regulating iron, with a particular focus on hepcidin, the master regulator of body iron homeostasis. Bone morphogenetic protein (BMP) signaling is the major pathway that is required for induction of hepcidin expression in response to increasing levels of iron. Strong links between iron homeostasis, BMP signaling, inflammation and atherosclerosis have been established in both mechanistic and human studies. This review summarizes the current understanding of the role of iron homeostasis and hepcidin in the development of atherosclerosis and discusses the BMP-hepcidin-ferroportin axis as a novel therapeutic target for the treatment of cardiovascular disease.

Hepcidin in morbidly obese women with non-alcoholic fatty liver disease

Background

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in Western countries. Both iron and lipid metabolism seem to be involved in its pathogenesis. We aimed to assess the relationship between levels of hepcidin, the master iron-regulatory protein, in plasma and the presence of NAFLD in morbidly obese (MO) patients, and to investigate the association between the hepatic expression of the main iron and lipid metabolism -related genes.

Materials and methods

Enzyme-linked immunosorbent assay was used to measure plasma hepcidin levels in 49 normal-weight control women, 23 MO women with normal liver (NL) histology and 46 MO women with NAFLD. The mRNA expression of hepcidin, the main iron metabolism-related genes, and the main lipid-metabolism genes was quantified by qRT-PCR in liver biopsies from members of the MO group undergoing bariatric surgery.

Results

Circulating hepcidin levels were significantly greater in MO than in normal-weight control women. However, there were no significant differences between MO women with NL and those with NAFLD. PCR analysis showed increased expression of hepcidin, FPN1, TfR1 and TfR2 in the liver of MO NAFLD women compared to those with NL. Moreover, a positive association of hepatic hepcidin mRNA expression and the iron metabolism-related genes was found with some key genes involved in the lipid metabolism.

Conclusion

These findings suggest that circulating hepcidin levels are associated with obesity but not with the presence of NAFLD. However, the hepatic expression of hepcidin and the iron metabolism-related genes seem to play a role in regulating lipid metabolism pathways in liver, which has implications for NAFLD pathogenesis.

The interplay between Th17 and T-regulatory responses as well as adipokines in the progression of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a chronic progressive liver disease, coupled with metabolic syndrome, which may progress to non-alcoholic steatohepatitis (NASH). Diabetes, obesity, hypertension, hypercholesterolemia, and hypertriglyceridemia are considered to be the most common causes leading to the incidence of NAFLD. It is assumed that the accumulation of lipid deposits in hepatocytes leads to production of proinflammatory cytokines that triggers the development of liver inflammation. Regulatory T cells (Tregs) play a critical role in regulating inflammatory processes in NASH, while T helper type 17 (Th17) might functionally oppose Treg-mediated responses. In addition, important mediators of hepatic steatosis are fatty hormones known as adipokines. We aimed to describe the significance and interaction between Treg and Th17-related cytokines as well as adipokines in pathogenesis and its potential use as biomarkers of NAFLD, especially with respect to progression to NASH.

Hyperferritinemia in patients with nonalcoholic fatty liver disease

Objective:

In liver diseases, hyperferritinemia (HYF) is related to injured cells in acquired and genetic conditions with or without iron overload. It is frequent in patients with nonalcoholic fatty liver disease (NAFLD), in which it is necessary to define the mean of HYF to establish the better approach for them. The present study evaluated the significance of elevated ferritin in patients with NAFLD and steatohepatitis (NASH).

Method:

The review was performed using search instruments of indexed scientific material, including MEDLINE (by PubMed), Web of Science, IBECS and LILACS, to identify articles published in Portuguese, English and Spanish, from 2005 to May, 2016. Studies eligible included place and year of publication, diagnose criteria to NAFLD, specifications of serum ferritin measurements and/or liver histopathologic study. Exclusion criteria included studies with patients with alcohol consumption ≥ 20 g/day and other liver diseases.

Results:

A total of 11 from 30 articles were selected. It included 3,564 patients and they were cross-sectional, retrospective, case series and case-control. The result's analyses showed in 10 of these studies a relationship between ferritin elevated serum levels and NAFLD/NASH with and without fibrosis and insulin resistance.

Conclusion:

Hyperferritinemia in patients with NAFLD/NASH is associated more frequently with hepatocellular injury than hemochromatosis. These data suggest the relevance to evaluate carefully HYF in patients with NAFLD/NASH to establish appropriate clinical approach.

Correlation between severity of ultrasonographic nonalcoholic fatty liver disease and cardiometabolic risk among Filipino wellness patients

Introduction: Nonalcoholic fatty liver disease (NAFLD) is a prevalent condition which is known to be related to factors that predispose to the development of coronary artery disease as well as development of metabolic syndrome. The study aimed to determine the association between ultrasound-based grading of hepatic steatosis with metabolic profile and estimated cardiovascular risk using the Framingham Risk Score (FRS).

Methods: This was a cross-sectional study on 100 Filipino patients without established cardiovascular disease who underwent a general wellness health evaluation. Cases with NAFLD diagnosed on the basis of ultrasound grading were analyzed. Comparison of demographics and metabolic parameters between grades of hepatic steatosis was performed using Kruskal Wallis test. FRS was used to assess cardiovascular risk with Spearman rank test for correlation with the degree of NAFLD.

Results: Mean age was 47 ± 9.6 years, with 70% males. Mean body mass index (BMI) was 28.7 ± 5.1. Most patients had grade I NAFLD (53%), 34% were grade II, and 13% were grade III. BMI (P =0.034), liver enzymes (alanine aminotransferase [ALT], P = 0.001; aspartate aminotransferase [AST], P = 0.00), triglycerides (P = 0.047), and fasting blood sugar [FBS] (P = 0.049) were associated with fatty liver grade. No association was noted with total cholesterol (P = 0.569), high density lipoprotein (HDL) (P = 0.220), and low density lipoprotein (LDL) (P = 0.792). Using the FRS 43% were stratified as low (<10% risk), 45% as intermediate (10%-20% risk) and 12% as high risk (>20% risk). Severity of fatty liver was directly correlated with the FRS (Spearman rank 0.741, P = 0.009).

Conclusion: Ultrasound-based grading of the severity of NAFLD is associated with abnormalities in the metabolic profile of patients. The FRS is correlated with increasing severity of NAFLD based on ultrasound. These findings suggest that the presence of NAFLD may be a marker for the presence of increased cardiovascular risk and may help identify patients who may benefit from more aggressive therapies to prevent development of adverse cardiovascular events.

Differences in hepatic expression of iron, inflammation and stress-related genes in patients with nonalcoholic steatohepatitis

 Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide. We have previously shown that hepatic reticuloendothelial system (RES) iron deposition is associated with an advanced degree of nonalcoholic steatohepatitis (NASH) in humans. In this study, we aimed to determine differentially expressed genes related to iron overload, inflammation and oxidative stress pathways, with the goal of identifying factors associated with NASH progression. Seventy five patients with NAFLD were evaluated for their biochemical parameters and their liver tissue analyzed for NASH histological characteristics. Gene expression analysis of pathways related to iron homeostasis, inflammation and oxidative stress was performed using real-time PCR. Gene expression was compared between subjects based on disease status and presence of hepatic iron staining. We observed increased gene expression of hepcidin (HAMP) (2.3 fold, p = 0.027), transmembrane serine proteinase 6 (TMPRSS6) (8.4 fold, p = 0.003), signal transducer and activator of transcription 3 (STAT3) (5.5 fold, p = 0.004), proinflammatory cytokines; IL-1? (2.7 fold, p = 0.046) and TNF-? (3.8 fold, p = 0.001) in patients with NASH. TMPRSS6, a negative regulator of HAMP, is overexpressed in patients with NASH and HIF1? (hypoxia inducible factor-1) is downregulated. NAFLD patients with hepatic iron deposition exhibited higher hepcidin expression (3.1 fold, p = 0.04) but lower expression of cytokines. In conclusion, we observed elevated hepatic HAMP expression in patients with NASH and in NAFLD patients who had hepatic iron deposition, while proinflammatory cytokines displayed elevated expression only in patients with NASH, suggesting a regulatory role for hepcidin in NAFL to NASH transition and in mitigating inflammatory responses.

Protective effects of glycyrrhizic acid from edible botanical glycyrrhiza glabra against non-alcoholic steatohepatitis in mice

Glycyrrhizic acid protects against non-alcoholic steatohepatitis in mice.

INFLUENCE OF OXIDATIVE STRESS AND OBESITY IN PATIENTS WITH NONALCOHOLIC STEATOHEPATITIS

BackgroundNonalcoholic steatohepatitis is considered the hepatic manifestation of metabolic syndrome and it is particularly associated to the insulin resistance, hypertension, obesity and abnormalities in lipid and glucose metabolism.ObjectiveConsidering the importance of obesity and oxidative stress in the pathophysiology of nonalcoholic steatohepatitis, this study aimed to evaluate the presence and association of the obesity and oxidative stress in this pathology.MethodsFifteen outpatients with nonalcoholic steatohepatitis (nonalcoholic steatohepatitis group), diagnosed according to the histopathological findings from the liver biopsy, and 15 body mass index-matched subjects (non nonalcoholic steatohepatitis group) without nonalcoholic steatohepatitis were included. All volunteers were registered in a Brazilian University Hospital. Nutritional assessment (weight, height, body mass index and waist circumference) and biochemical analysis (fasting glucose, liver enzymes, lipid profile, leptin, superoxide dismutase, glutathione peroxidase, vitamins C and E, catalase and 8-isoprostane) were performed for all the participants. The student t test was used for statistical analysis, with P<0.05 as the significant factor.ResultsNonalcoholic steatohepatitis patients had higher fasting glucose, hepatic enzymes (serum aspartate aminotransaminase, alanine aminotransaminase, gamma glutamyl transferase, alkaline phosphatase), triglycerides and superoxide dismutase and lower glutathione peroxidase values than non nonalcoholic steatohepatitis individuals.ConclusionThis paper demonstrates that only the presence of obesity is not enough to trigger alterations in all the studied biomarkers. Despite the majority of oxidative stress markers being found to be similar in both conditions, the nonalcoholic steatohepatitis subjects could be slightly more affected than the non nonalcoholic steatohepatitis individuals.

Normocaloric low cholesterol diet modulates Th17/Treg balance in patients with chronic hepatitis C virus infection

Hepatitis C virus (HCV) infection is associated with hepatic and extrahepatic manifestations, including immunological disorders. Chronic Hepatitis C (CHC) is often characterized by cholesterol and lipid metabolism alterations, leading to hepatic steatosis. Cholesterol metabolism, in fact, is crucial for the viral life cycle. Recent works described that a higher dietary cholesterol intake is associated with the progression of HCV-related liver disease. CHC patients have increased levels of T helper 17 (Th17)-cells, a lymphocytic population involved in the pathogenesis of liver inflammation and autoimmune hepatitis. The balance between Th17 and regulatory T (Treg) cells is crucial for chronic inflammation and autoimmunity. Th17-cell differentiation is deeply influenced by the activation LXRs, nuclear receptors modulating cholesterol homeostasis. Moreover, HCV may affect these nuclear receptors, and cholesterol metabolism, through both direct and indirect mechanisms. On these bases, we hypothesized that modulation of cholesterol levels through Normocaloric Low Cholesterol Diet (NLCD) may represent an innovative strategy to reduce the progression of HCV infection, through the modulation of peripheral Th17/Treg balance. To this end, we performed a pilot study to investigate whether a Normocaloric Low Cholesterol Diet may be able to modulate Th17/Treg balance in patients affected by chronic HCV infection. After 30 days of NLCD CHC patients showed a significant reduction in Th17 cells frequency, which correlated with strong reduction of IL-17 and IL-22 serum levels. At the same time, we appreciated an increase in the percentage of Treg cells, thus improving Treg/Th17 balance. Moreover, we observed an increased expression of LXRs and their target genes: SREBP-1c and ABCA-1. In conclusion, NLCD finely regulates Th17/Treg balance, improving immune system response in CHC patients. This study could pave the way for new treatments of CHC patients, suggesting that change in lifestyle could support the management of these patients, promoting well-being and possibly hindering disease progression.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02038387.

Novel pathway for iron deficiency in pediatric non-alcoholic steatohepatitis

BACKGROUND & AIMS

Iron may be an important factor in the pathogenesis of non-alcoholic steatohepatitis (NASH) as it catalyzes the production of potent reactive oxygen species. We aim to examine iron status in pediatric NASH.

METHODS

Serum indices of NASH patients (N = 36) were compared to those in the U.S. National Health and Nutrition Examination Survey database (N = 802). Iron related gene expression was examined in NASH livers and normal livers, using microarray and quantitative real-time PCR (10 NASH livers and 6 controls). Transferrin and catalase expression were also examined in hydrogen peroxide treated HepG2 cells.

RESULTS

Serum iron concentration (P < 0.01) and soluble transferrin receptor 1 (P < 0.0001) were decreased while serum ferritin was elevated in NASH patients (P < 0.01). No detectable iron was observed in NASH liver by Perls' Prussian blue staining. Transferrin (P < 0.01) and transferrin receptor 2 (P < 0.01) mRNA were elevated in NASH patients. Of particular interest, transferrin mRNA was positively correlated with catalase mRNA (r = 0.9338, P < 0.0001). H2O2 treatment of HepG2 cells induced mRNA expression of transferrin and catalase.

CONCLUSIONS

Pediatric NASH patients exhibited decreased serum iron concentration and no detectable iron was observed in any NASH liver by Perls' Prussian blue staining. These changes are consistent with the facts that most NASH patients are obese and exhibit chronic inflammation. In line with a status of iron deficiency, gene expression studies suggested decreased expression of transferrin and transferrin receptor 2 in NASH livers. Induction of transferrin by H2O2, and consequently, decreased iron absorption, suggests a novel mechanism for iron deficiency in NASH patients.

Serum hepcidin levels are associated with obesity but not liver disease

OBJECTIVE

Hepcidin is regulated by anemia and inflammation. It is primarily expressed in the liver but studies have reported its expression in adipose tissue. The relationship between BMI and serum hepcidin and the relationship between liver histology and serum hepcidin in the morbidly obese was investigated.

METHODS

Serum and liver tissue from patients undergoing bariatric surgery (bariatric cohort, n = 105) and serum from healthy blood donors (n = 60) were used to conduct this study. Serum hepcidin was measured using sandwich ELISA, highly specific for hepcidin-25. Serum ferritin, IL-6, IL-1β and liver function biochemistries were also measured.

RESULTS

After controlling for covariates, BMI ≥ 35 kg/m(2) was significantly associated with higher serum hepcidin level compared to individuals with lower BMI groups (17.7 ± 11.5 vs. 3.3 ± 4.7 ng/ml, P = 0.002). The presence of NAFLD was not associated with higher serum levels of hepcidin (multivariate P = 0.37). There was no association between serum hepcidin levels and liver histology (presence of steatohepatitis, advanced fibrosis, or NAFLD activity score) in the bariatric cohort.

CONCLUSIONS

Obesity, but not the presence of NAFLD was associated with serum hepcidin levels. There was no association between serum hepcidin and liver histology in the morbidly obese undergoing bariatric surgery.

Serum hepcidin levels are associated with serum triglycerides and interleukin-6 concentrations in patients with end-stage renal disease

Hepcidin has emerged as a peptide with a key role in the regulation of iron homeostasis in patients with chronic kidney disease (CKD), having a strong dependence on inflammation. Recent studies reveal that hepcidin may be also associated with the progression of atherosclerosis. This study was performed to analyze the relation of hepcidin to markers of atherosclerosis and inflammation in patients on dialysis. A total of 90 individuals were enrolled. Sixty patients with end-stage renal disease, who were on hemodialysis (HD) (N = 30) and peritoneal dialysis (N = 30) were compared with 30 normal controls (NC). Age, body mass index, time on dialysis, serum lipids, C-reactive protein (CRP) and interleukin-6 (IL-6) were measured and analyzed in correlation with hepcidin concentration. It was found that patients on HD and peritoneal dialysis have significantly higher (P < 0.0001) levels of hepcidin, CRP and IL-6 than NC. Hepcidin in dialysis patients is significantly related to age (r = 0.373, P = 0.012), serum triglycerides (r = 0.401, P = 0.005), HDL-C (r = -0.268, P = 0.048), CRP (r = 0.436, P = 0.0007) and IL-6 (r = 0.569, P < 0.0001). In multiple regression analysis, hepcidin correlated independently with triglycerides (β = 0.402, P = 0.041) and IL-6 (β = 0.559, P = 0.006). Moreover, patients with high triglycerides in combination with high IL-6 levels have significantly increased concentrations of hepcidin than those with low triglycerides and low IL-6 levels (P < 0.0001). Elevated levels of hepcidin in patients with CKD on dialysis may be related to the occurrence of high triglycerides and high IL-6 serum concentrations. This probably suggests that hepcidin may play a role to the progression of atherosclerosis and inflammation, but this hypothesis should be further evaluated.

Is nonalcoholic fatty liver disease the hepatic expression of the metabolic syndrome?

Nonalcoholic fatty liver disease (NAFLD) is generally considered as the hepatic manifestation of the metabolic syndrome (MS). Although there is no doubt that NAFLD is tightly linked to the MS, the diagnosis of NAFLD encompasses a broad range of histological entities and as a composite phenotype may be hindering attempts to understand the mechanistic basis of these variants. The awareness that NAFLD is not solely and invariably associated with the MS is a useful means to help direct future studies. We should be aware that mechanisms other than insulin resistance may contribute to the chronic inflammatory processes that underpin the development of liver fat accumulation and the subsequent architectural distortion of the liver. Further studies with special focus on hemoglobin as a risk factor for the development of NAFLD in the absence of MS should be performed.

Lower serum hepcidin and greater parenchymal iron in nonalcoholic fatty liver disease patients with C282Y HFE mutations

Hepcidin regulation is linked to both iron and inflammatory signals and may influence iron loading in nonalcoholic steatohepatitis (NASH). The aim of this study was to examine the relationships among HFE genotype, serum hepcidin level, hepatic iron deposition, and histology in nonalcoholic fatty liver disease (NAFLD). Single-nucleotide polymorphism genotyping for C282Y (rs1800562) and H63D (rs1799945) HFE mutations was performed in 786 adult subjects in the NASH Clinical Research Network (CRN). Clinical, histologic, and laboratory data were compared using nonparametric statistics and multivariate logistic regression. NAFLD patients with C282Y, but not H63D mutations, had lower median serum hepcidin levels (57 versus 65 ng/mL; P = 0.01) and higher mean hepatocellular (HC) iron grades (0.59 versus 0.28; P < 0.001), compared to wild-type (WT) subjects. Subjects with hepatic iron deposition had higher serum hepcidin levels than subjects without iron for all HFE genotypes (P < 0.0001). Hepcidin levels were highest among patients with mixed HC/reticuloendothelial system cell (RES) iron deposition. H63D mutations were associated with higher steatosis grades and NAFLD activity scores (odds ratio [OR], ≥1.4; 95% confidence interval [CI]: >1.0, ≤2.5; P ≤ 0.041), compared to WT, but not with either HC or RES iron. NAFLD patients with C282Y mutations had less ballooning or NASH (OR, ≤0.62; 95% CI: >0.39, <0.94; P ≤ 0.024), compared to WT subjects.

CONCLUSIONS

The presence of C282Y mutations in patients with NAFLD is associated with greater HC iron deposition and decreased serum hepcidin levels, and there is a positive relationship between hepatic iron stores and serum hepcidin level across all HFE genotypes. These data suggest that body iron stores are the major determinant of hepcidin regulation in NAFLD, regardless of HFE genotype. A potential role for H63D mutations in NAFLD pathogenesis is possible through iron-independent mechanisms.

Iron and steatohepatitis

As the main iron storage site in the body and the main source of the iron-regulatory hormone, hepcidin, the liver plays a pivotal role in iron homeostasis. A variable degree of hepatic iron accumulation has long been recognized in a number of chronic liver diseases. Both alcoholic and non-alcoholic steatohepatitis display increased iron deposits in the liver, with an hepatocellular, mesenchymal, or mixed pattern, and recent reports have documented a concomitant aberrant hepcidin expression that could be linked to different coincidental pathogenic events (e.g. the etiological agent itself, necroinflammation, metabolic derangements, genetic predisposition). The present study reviews the pathogenic mechanisms of iron accumulation in steatohepatitis during alcoholic and non-alcoholic liver disease and the role of excess iron in chronic disease progression.