Vascular Damage in Patients with Nonalcoholic Fatty Liver Disease: Possible Role of Iron and Ferritin

The role and mechanism of various trace elements in atherosclerosis

Atherosclerosis is a slow and complex disease that involves various factors, including lipid metabolism disorders, oxygen-free radical production, inflammatory cell infiltration, platelet adhesion and aggregation, and local thrombosis. Trace elements play a crucial role in human health. Many trace elements, especially metallic ones, not only maintain the normal functions of organs but also participate in basic metabolic processes. The latest studies have revealed a close correlation between trace elements and the occurrence and progression of atherosclerosis. The imbalance of these trace elements can induce atherosclerosis or accelerate its progression through various mechanisms, which poses a significant threat to human health. Therefore, exploring the specific mechanism of trace elements on atherosclerosis is highly significant. In this review, we summarized the roles and mechanisms of iron, copper, zinc, magnesium, and selenium homeostasis and imbalance in atherosclerosis development, in order to identify novel targets and therapeutic strategies for treating atherosclerosis.

Dual nature of ferritin for hematologic, liver functional, and metabolic parameters in older diabetic patients

This study explored the association between ferritin with hematologic, liver functional, and metabolic parameters in older diabetic patients. A total of 210 diabetic patients aged 65 or older were classified into four groups according to the reference range of serum ferritin. Demographic variables and health-related lifestyle factors were obtained through the utilization of a standardized questionnaire. Anthropometric measures, blood pressure, hematology test, and biochemical assessment were also performed. Among all patients, 29.5% had anemia. The percentage of anemia in groups low ferritin (< 40 μg/L), lower side within the reference range (40-120 μg/L), higher side within the reference range (121-200 μg/L), and high ferritin levels (> 200 μg/L) were 50.0, 27.7, 20.5, and 24.2% (P = 0.025), respectively. Low ferritin levels had a higher risk of anemia and a high red blood cell distribution width (RDW). High ferritin levels were associated with a higher risk of high glutamate pyruvate transaminase, obesity, high fasting blood glucose (FBG), and high postprandial blood glucose. The higher side within the reference range of ferritin also showed a higher risk of high FBG and high glycated hemoglobin. Nevertheless, there was no significant association between ferritin and inflammation marker, serum lipids or blood pressure. Overall, ferritin demonstrates a dual nature in older diabetic patients: low ferritin levels are linked to anemia or elevated RDW, while high levels are linked to obesity, increased liver enzymes, and worse glycemia control.

Liver Fat Scores for Noninvasive Diagnosis and Monitoring of Nonalcoholic Fatty Liver Disease in Epidemiological and Clinical Studies

Nonalcoholic fatty liver disease (NAFLD) is strongly associated with the metabolic syndrome and type 2 diabetes and independently contributes to long-term complications. Being often asymptomatic but reversible, it would require population-wide screening, but direct diagnostics are either too invasive (liver biopsy), costly (MRI) or depending on the examiner's expertise (ultrasonography). Hepatosteatosis is usually accommodated by features of the metabolic syndrome (e.g. obesity, disturbances in triglyceride and glucose metabolism), and signs of hepatocellular damage, all of which are reflected by biomarkers, which poorly predict NAFLD as single item, but provide a cheap diagnostic alternative when integrated into composite liver fat indices. Fatty liver index, NAFLD LFS, and hepatic steatosis index are common and accurate indices for NAFLD prediction, but show limited accuracy for liver fat quantification. Other indices are rarely used. Hepatic fibrosis scores are commonly used in clinical practice, but their mandatory reflection of fibrotic reorganization, hepatic injury or systemic sequelae reduces sensitivity for the diagnosis of simple steatosis. Diet-induced liver fat changes are poorly reflected by liver fat indices, depending on the intervention and its specific impact of weight loss on NAFLD. This limited validity in longitudinal settings stimulates research for new equations. Adipokines, hepatokines, markers of cellular integrity, genetic variants but also simple and inexpensive routine parameters might be potential components. Currently, liver fat indices lack precision for NAFLD prediction or monitoring in individual patients, but in large cohorts they may substitute nonexistent imaging data and serve as a compound biomarker of metabolic syndrome and its cardiometabolic sequelae.

Low Serum Soluble Transferrin Receptor Levels Are Associated with Poor Prognosis in Patients with Hepatitis B Virus-Related Acute-on-Chronic Liver Failure

Iron metabolism disorder is closely related to acute-on-chronic liver failure (ACLF). This study was conducted to analyze the serum levels of soluble transferrin receptor (sTfR) in hepatitis B virus (HBV)-related ACLF and to evaluate the predictive value of sTfR for the short-term prognosis of HBV-ACLF. A total of 359 patients, including 139 with HBV-ACLF, 103 with chronic hepatitis B (CHB), and 117 healthy controls (HCs), participated in this study. We measured serum levels of ferritin, transferrin, and sTfR using nephelometry and performed data analysis using SPSS software. Ferritin levels were significantly higher in HBV-ACLF patients (both P < 0.001), while transferrin and sTfR were significantly lower (all P < 0.001) than in patients with CHB and HCs. Spearman correlation analysis demonstrated that serum sTfR significantly correlated with the alanine aminotransferase (ALT) (r = -0.366, P < 0.001), aspartate aminotransferase (AST) (r = -0.322, P < 0.001), total bilirubin (TBIL) (r = -0.222, P = 0.009), alpha fetoprotein (AFP) (r = 0.329, P < 0.001), prothrombin time-international normalization ratio (PT-INR) (r = -0.428, P < 0.001), and model for end-stage liver disease (MELD) (r = -0.459, P < 0.001). Nonsurviving HBV-ACLF patients who died within 30 days had much lower serum sTfR levels than surviving patients (P < 0.001). Logistic regression analysis showed that decreased serum sTfR levels were independently associated with 30-day mortality in patients with HBV-ACLF (P = 0.003). Receiver operating characteristic (ROC) curve analysis for predicting 30-day mortality showed that the area under the curve (AUC) for serum sTfR was 0.813 (95% CI: 0.738-0.874, P < 0.001). This was similar to that of the MELD score (AUC = 0.812, 95% CI: 0.737-0.873, P < 0.001). Serum sTfR combined with MELD score significantly improved the predictive capacity for 30-day mortality in patients with HBV-ACLF (AUC = 0.871, 95% CI: 0.803-0.922, P < 0.001). Kaplan-Meier analysis revealed that the overall cumulative 30-day mortality rate was significantly higher in patients with serum sTfR levels ≤ 0.55 mg/L compared to those with serum sTfR levels > 0.55 mg/L (P < 0.001).

Association of non-alcoholic fatty liver disease with left ventricular changes in treatment-naive patients with uncomplicated hypertension

Background and aims

Cardiac structural and functional changes have been demonstrated in patients with non-alcoholic fatty liver disease (NAFLD). Because of the frequent association of NAFLD with hypertension, we aimed to examine the relationship of liver steatosis with left ventricular (LV) changes in patients with hypertension.

Materials and methods

In a cross-sectional study, we included 360 untreated, essential hypertensive patients who were free of major cardiovascular and renal complications. Liver steatosis was assessed by three different biochemical scores (NAFLD Liver Fat Score, LFS; Fatty Liver Index, FLI; Hepatic Steatosis Index, HSI). Echocardiography was performed with standard B-mode and tissue-Doppler imaging.

Results

LV hypertrophy was present in 19.4% and LV diastolic dysfunction in 49.2% of patients who had significantly higher body mass index (BMI), blood pressure (BP), and homeostatic model assessment (HOMA) index and higher frequency of the metabolic syndrome and liver steatosis that was defined by presence of 2 or more positive scores. LV mass index increased progressively across patients who had none, 1, or 2 or more liver steatosis scores, with associated progressive worsening of LV diastolic function. LV mass index was significantly and positively correlated with age, BMI, BP, HOMA-index, LFS, and HSI. Logistic regression analysis showed that age, BP, and liver steatosis scores independently predicted LV hypertrophy and diastolic dysfunction. Liver steatosis independently predicted LV dysfunction but not LV hypertrophy even after inclusion in analysis of the HOMA-index.

Conclusion

NAFLD is associated with LV hypertrophy and diastolic dysfunction in untreated patients with hypertension. In hypertension, NAFLD could contribute to LV diastolic dysfunction with mechanisms unrelated to insulin resistance.

An Iron Refractory Phenotype in Obese Adipose Tissue Macrophages Leads to Adipocyte Iron Overload

Adipocyte iron overload is a maladaptation associated with obesity and insulin resistance. The objective of the current study was to determine whether and how adipose tissue macrophages (ATMs) regulate adipocyte iron concentrations and whether this is impacted by obesity. Using bone marrow-derived macrophages (BMDMs) polarized to M0, M1, M2, or metabolically activated (MMe) phenotypes, we showed that MMe BMDMs and ATMs from obese mice have reduced expression of several iron-related proteins. Furthermore, the bioenergetic response to iron in obese ATMs was hampered. ATMs from iron-injected lean mice increased their glycolytic and respiratory capacities, thus maintaining metabolic flexibility, while ATMs from obese mice did not. Using an isotope-based system, we found that iron exchange between BMDMs and adipocytes was regulated by macrophage phenotype. At the end of the co-culture, MMe macrophages transferred and received more iron from adipocytes than M0, M1, and M2 macrophages. This culminated in a decrease in total iron in MMe macrophages and an increase in total iron in adipocytes compared with M2 macrophages. Taken together, in the MMe condition, the redistribution of iron is biased toward macrophage iron deficiency and simultaneous adipocyte iron overload. These data suggest that obesity changes the communication of iron between adipocytes and macrophages and that rectifying this iron communication channel may be a novel therapeutic target to alleviate insulin resistance.

Selenotranscriptome Network in Non-alcoholic Fatty Liver Disease

Observational studies indicate that selenium may contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Transcriptomic exploration of the aetiology and progression of NAFLD may offer insight into the role selenium plays in this disease. This study compared gene expression levels of known selenoprotein pathways between individuals with a healthy liver to those with NAFLD. Publicly available gene expression databases were searched for studies that measured global gene expression in liver samples from patients with steatosis and non-alcoholic steatohepatitis (NASH) and healthy controls (with [HOC] or without [HC] obesity). A subset of five selenoprotein-related pathways (164 genes) were assessed in the four datasets included in this analysis. The gene TXNRD3 was less expressed in both disease groups when compared with HOC. SCLY and SELENOO were less expressed in NASH when compared with HC. SELENOM, DIO1, GPX2, and GPX3 were highly expressed in NASH when compared to HOC. Disease groups had lower expression of iron-associated transporters and higher expression of ferritin-encoding sub-units, consistent with dysregulation of iron metabolism often observed in NAFLD. Our bioinformatics analysis suggests that the NAFLD liver may have lower selenium levels than a disease-free liver, which may be associated with a disrupted iron metabolism. Our findings indicate that gene expression variation may be associated with the progressive risk of NAFLD.

Nutrients, Genetic Factors, and Their Interaction in Non-Alcoholic Fatty Liver Disease and Cardiovascular Disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in Western countries and expose patients to increased risk of hepatic and cardiovascular (CV) morbidity and mortality. Both environmental factors and genetic predisposition contribute to the risk. An inappropriate diet, rich in refined carbohydrates, especially fructose, and saturated fats, and poor in fibers, polyunsaturated fats, and vitamins is one of the main key factors, as well as the polymorphism of patatin-like phospholipase domain containing 3 (PNPLA3 gene) for NAFLD and the apolipoproteins and the peroxisome proliferator-activated receptor (PPAR) family for the cardiovascular damage. Beyond genetic influence, also epigenetics modifications are responsible for various clinical manifestations of both hepatic and CV disease. Interestingly, data are accumulating on the interplay between diet and genetic and epigenetic modifications, modulating pathogenetic pathways in NAFLD and CV disease. We report the main evidence from literature on the influence of both macro and micronutrients in NAFLD and CV damage and the role of genetics either alone or combined with diet in increasing the risk of developing both diseases. Understanding the interaction between metabolic alterations, genetics and diet are essential to treat the diseases and tailoring nutritional therapy to control NAFLD and CV risk.

N-Acetyl Cysteine Attenuates the Sarcopenia and Muscle Apoptosis Induced by Chronic Liver Disease

Background:

Sarcopenia is characterized by the loss of muscle mass and strength (muscle atrophy) because of aging or chronic diseases, such as chronic liver disease (CLD). Different mechanisms are involved in skeletal muscle atrophy, including decreased muscle fibre diameter and myosin heavy chain levels and increased ubiquitin–proteasome pathway activity, oxidative stress and myonuclear apoptosis. We recently found that all these mechanisms, except myonuclear apoptosis, which was not evaluated in the previous study, were involved in muscle atrophy associated with hepatotoxin 5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-induced CLD.

Objective:

In the present study, we evaluated the involvement of myonuclear apoptosis in CLD-associated sarcopenia and the effect of N-acetyl cysteine (NAC) treatment on muscle strength and apoptosis, using a DDC-supplemented diet-fed mouse model.

Methods:

Four-month-old male C57BL6 mice were fed with a standard or DDCsupplemented diet for six weeks in the absence or presence of NAC treatment.

Results:

Our results showed that NAC attenuated the decrease in muscle fibre diameter and muscle strength associated with CLD-induced muscle wasting in gastrocnemius (GA) muscle of DDC-supplemented diet-fed mice. In addition, in GA muscle of the mice fed with DDC-supplemented diet-induced CLD showed increased myonuclear apoptosis compared with the GA muscle of the control diet-fed mice, as evidenced by increased apoptotic nuclei number, caspase-8 and caspase-9 expression, enzymatic activity of caspase-3 and BAX/BCL-2 ratio. NAC treatment inhibited all the mechanisms associated with myonuclear apoptosis in the GA muscle.

Conclusion:

To our knowledge, this is the first study which reports the redox regulation of muscle strength and myonuclear apoptosis in CLD-induced sarcopenia.

No effects without causes: the Iron Dysregulation and Dormant Microbes hypothesis for chronic, inflammatory diseases

Since the successful conquest of many acute, communicable (infectious) diseases through the use of vaccines and antibiotics, the currently most prevalent diseases are chronic and progressive in nature, and are all accompanied by inflammation. These diseases include neurodegenerative (e.g. Alzheimer's, Parkinson's), vascular (e.g. atherosclerosis, pre-eclampsia, type 2 diabetes) and autoimmune (e.g. rheumatoid arthritis and multiple sclerosis) diseases that may appear to have little in common. In fact they all share significant features, in particular chronic inflammation and its attendant inflammatory cytokines. Such effects do not happen without underlying and initially 'external' causes, and it is of interest to seek these causes. Taking a systems approach, we argue that these causes include (i) stress-induced iron dysregulation, and (ii) its ability to awaken dormant, non-replicating microbes with which the host has become infected. Other external causes may be dietary. Such microbes are capable of shedding small, but functionally significant amounts of highly inflammagenic molecules such as lipopolysaccharide and lipoteichoic acid. Sequelae include significant coagulopathies, not least the recently discovered amyloidogenic clotting of blood, leading to cell death and the release of further inflammagens. The extensive evidence discussed here implies, as was found with ulcers, that almost all chronic, infectious diseases do in fact harbour a microbial component. What differs is simply the microbes and the anatomical location from and at which they exert damage. This analysis offers novel avenues for diagnosis and treatment.

The relationship between serum ferritin levels and serum lipids and HDL function with respect to age and gender

Elevated serum ferritin (SFer) levels have been associated with chronic diseases such as coronary heart disease and diabetes mellitus type 2. The aim of this study was to examine the relationship between SFer levels and serum lipid parameters, and how this relation changes in terms of age and gender. Additionally, we investigated a possible relationship between SFer levels and high-density lipoprotein (HDL) function. SFer levels and lipid panel (total cholesterol (TC), triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C) and HDL-C) of 4205 people (3139 women, 1066 men) were examined retrospectively. Study population was classified according to age and gender. Separately, 100 subjects (52 women, 48 men) were randomly recruited to investigate the relation between SFer levels, and HDL dependent paraoxonase-1 (PON1) and arylesterase (ARE) activities. In all age groups, women’s SFer levels were found to be significantly lower and HDL-C levels significantly higher compared to men. In the 50-70 ages range, TC and LDL-C levels of women were found to be significantly higher than those of men (P < 0.01). SFer levels tended to increase with age in women. Correlation analyses revealed a negative correlation between levels of SFer and HDL-C, while positive correlations existed between levels of SFer, and TC, TG and LDL-C. There was no significant correlation between SFer levels and PON1 or ARE activities. The finding that increased SFer levels are accompanied by increased serum TC, TG and LDL-C levels may help us to explain the increased risk of metabolic disorders and cardiovascular disease in postmenopausal women.

NAFLD: Is There Anything New under the Sun?

Nonalcoholic fatty liver disease (NAFLD) is an "umbrella" definition that encompasses a spectrum of histological liver changes ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) with/without fibrosis, "cryptogenic" cirrhosis, and hepatocellular carcinoma (HCC), occurring in a dysmetabolic milieu, though in the absence of excessive alcohol consumption and other competing etiologies of chronic liver disease [1].[...].