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Iron-Overload triggers ADAM-17 mediated inflammation in Severe Alcoholic Hepatitis.

ABSTRACT: Severe alcoholic hepatitis (SAH) is associated with iron accumulation in hepatocytes/macrophages. This possibly correlates with inflammation and stress but the exact mechanism still remains obscure. To understand the role of iron and the mechanisms of systemic iron-overload, a transcriptomic study of liver and Peripheral Blood -Mononuclear-Cells (PBMCs) was undertaken in SAH patients, with and without hepatic iron-overload. Our results show that iron-overload in hepatocytes/macrophages is due to an increased expression of iron-loading receptors and CD163 signaling cascade. Increase in labile iron pool induces expression of iron-loading, oxidative-stress and inflammatory genes along with expression of CD163 and ADAM17. Increased liver iron correlated with circulatory iron, TNF-?, macrophage activation (sCD163) and peroxide-stress in CD163⁺macrophages in patients who were iron-overloaded and died. Circulatory TNF-? and sCD163 levels were associated with poor outcome. Temporal iron/Fenton stress induced in healthy monocyte-derived-macrophage (MDM)/Tohoku-Hospital-Pediatrics-1(THP1) cells showed higher expression of iron-regulatory, inflammatory and oxidative-stress genes. These genes could be suppressed by iron-chelation. These results suggest that iron mediates inflammation through ADAM17 induction, resulting in macrophage activation and increased shedding of TNF-? and sCD163. These events could be inhibited with iron chelation or with ADAM17-blockade, postulating a therapeutic strategy for SAH patients with iron overload.

SUBMITTER: Maras JS

PROVIDER: S-EPMC6035223 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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Iron-Overload triggers ADAM-17 mediated inflammation in Severe Alcoholic Hepatitis.

Maras Jaswinder Singh JS Das Sukanta S Sharma Sachin S Sukriti Sukriti S Kumar Jitendra J Vyas Ashish Kumar AK Kumar Dhananjay D Bhat Adil A Yadav Gaurav G Choudhary Manish Chandra MC Sharma Shvetank S Kumar Guresh G Bihari Chhagan C Trehanpati Nirupma N Maiwall Rakhi R Sarin Shiv Kumar SK

Scientific reports 20180706 1

Severe alcoholic hepatitis (SAH) is associated with iron accumulation in hepatocytes/macrophages. This possibly correlates with inflammation and stress but the exact mechanism still remains obscure. To understand the role of iron and the mechanisms of systemic iron-overload, a transcriptomic study of liver and Peripheral Blood -Mononuclear-Cells (PBMCs) was undertaken in SAH patients, with and without hepatic iron-overload. Our results show that iron-overload in hepatocytes/macrophages is due to ...[more]

PMID: 29980709

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Project description:Hyperoxidized albumin promotes inflammation and modulates several immune cells in severe alcoholic hepatitis (SAH). Platelets mediate inflammation by interacting with immune cells, endothelium, and other cells. The role of hyperoxidized albumin in platelet activation and alteration of platelet phenotype/functions is not known. Quantitative platelet proteomics performed in 10 patients with SAH was compared with 10 patients with alcoholic cirrhosis and 10 healthy controls, respectively. Dysregulated pathways were identified and validated in a separate cohort (n = 40). Healthy platelets were exposed to patient plasma or purified albumin or ex vivo modified albumin (human-mercaptalbumin, humannonmercaptalbumin-1, and human nonmercaptalbumin 2) in the presence or absence of CD36 blockade, and platelet secretome was analyzed. Two hundred and two up-regulated proteins linked to platelet activation, complement regulation, lipid transportation, and 321 down-regulated proteins related to platelet hemostasis and coagulation (fold change ± 1.5, P < 0.01) were identified. Blood transcription module enrichment showed an inflammatory phenotype of SAH platelet. Increased level of platelet factor-4, P-selectin, and soluble cluster of differentiation-40 ligand correlated with severity (Model for End-Stage Liver Disease score, r > 0.3, P < 0.05) in SAH. Transcripts linked to platelet activation (increased) and granular secretions (decreased in SAH) correlated with disease severity. SNARE (soluble-N-ethylmaleimide-sensitive-factor-activating-protein-receptor) complex proteins (SNAP-23 [synaptosomal-associated protein 23] and VAMP-8 [vesicle-associated membrane protein 3]) were down-regulated in SAH platelets (P < 0.05). In vitro stimulation of healthy platelets showed enhanced activation with patient plasma, or purified albumin-treatment blocking of CD36 blunted this effect (P < 0.05). Ex vivo modified albumin (primarily nonmercaptalbumin-human nonmercaptalbumin 2 [HNA2; 1 mg/mL]) showed high activation and aggregation and intracellular reactive oxygen species production in healthy platelets (P < 0.05), which significantly reduced after CD36 neutralization. Platelet secretome showed reduced inflammatory mediators and increased repair proteins. Conclusion: Hyperoxidized albumin triggers platelet activation (possibly through the CD36 receptor), promotes inflammation and oxidative stress, and contributes to disease severity in patients with SAH.

Project description:Non-alcoholic steatohepatitis (NASH) is a progressive form of non-alcoholic fatty liver disease (NAFLD) that causes cirrhosis and hepatocellular carcinoma. Iron is an essential trace element in the body; however, excess iron can cause tissue damage and dysfunction. Iron overload is often observed in patients with NASH, and the amount of iron accumulated in the liver positively correlates with the histological severity of NASH. Ferroptosis, a novel form of iron-dependent cell death, is caused by the accumulation of lipid peroxidation and oxidative stress and is related to NASH. In addition, ferroptosis is closely related to autophagy, an intracellular self-degradation process. Although autophagy has many beneficial effects, it may also be harmful to the organism, for example, inducing ferroptosis. It is unclear whether iron overload aggravates NASH via autophagy. The aim of this research is to determine the mechanism by which iron overload induces ferroptosis via autophagy and aggravates NASH. Stroke-prone spontaneously hypertensive rats (SHRSP5/Dmcr) were divided into two groups and fed a high-fat and high-cholesterol (HFC) diet for eight weeks. Iron dextran was administered to the Fe group in addition to the HFC diet. Blood analysis, histological staining, calcineurin activity assay, quantitative reverse transcription polymerase chain reaction (RT-PCR), immunofluorescence staining, and electron microscopy were performed. The results showed that iron overload promoted autophagy via nuclear translocation of transcription factor EB (TFEB) and induced ferritinophagy, which is the autophagic degradation of ferritin. In addition, the HFC diet induced lipophagy, the autophagic degradation of lipid droplets. The Fe group also exhibited promoted ferroptosis and aggravated hepatic inflammation and fibrosis. In conclusion, iron overload accelerates ferritinophagy and lipophagy, aggravating NASH pathology via ferroptosis. These findings indicate the therapeutic potential of inhibiting autophagy and ferroptosis for treating NASH.

Dataset Information

Iron-Overload triggers ADAM-17 mediated inflammation in Severe Alcoholic Hepatitis.

Publications

Iron-Overload triggers ADAM-17 mediated inflammation in Severe Alcoholic Hepatitis.

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