Iron: Innocent bystander or vicious culprit in COVID-19 pathogenesis?

The coronavirus 2 (SARS-CoV-2) pandemic is viciously spreading through the continents with rapidly increasing mortality rates. Current management of COVID-19 is based on the premise that respiratory failure is the leading cause of mortality. However, mounting evidence links accelerated pathogenesis in gravely ill COVID-19 patients to a hyper-inflammatory state involving a cytokine storm. Several components of the heightened inflammatory state were addressed as therapeutic targets. Another key component of the heightened inflammatory state is hyper-ferritinemia which reportedly identifies patients with increased mortality risk. In spite of its strong association with mortality, it is not yet clear if hyper-ferritinemia in COVID-19 patients is merely a systemic marker of disease progression, or a key modulator in disease pathogenesis. Here we address implications of a possible role for hyper-ferritinemia, and altered iron homeostasis in COVID-19 pathogenesis, and potential therapeutic targets in this regard.

Changes in the Serum Hepcidin-to-ferritin Ratio with Erythroferrone after Hepatitis C Virus Eradication Using Direct-acting Antiviral Agents.

Objective Hepcidin is a master iron regulator hormone produced by the liver, but precise mechanism underlying its involvement in iron overload in hepatitis C virus (HCV) infection remains unclear. We investigated the serum hepcidin levels against iron overload before and after HCV eradication. Methods We prospectively investigated the iron metabolism characteristics in 24 patients with HCV genotype 1b infection before and after treatment. We also assessed the serum erythroferrone (ERFE) levels to investigate its association with iron metabolism changes. Patients were treated with Ledipasvir 90 mg and Sofosbuvir 400 mg once daily for 12 weeks and observed for 12 more weeks in order to evaluate their sustained virological response. Results Serum hepcidin levels at baseline were in the normal range, although serum ferritin levels were increased. After HCV eradication, both serum ferritin and hepcidin levels were significantly decreased at 24 weeks from baseline (p<0.001, p=0.006, respectively). However, the serum hepcidin-to-ferritin ratios were significantly increased (p<0.001). In addition, the serum ERFE levels were significantly decreased (p<0.001). Increases in the serum hepcidin-to-ferritin ratios were correlated with decreases in the serum ERFE levels (ρ=-0.422, p=0.039). Conclusion Serum hepcidin levels were relatively low against ferritin levels in HCV infection. However, after HCV eradication, the serum hepcidin-to-ferritin ratios were increased. These results indicate the improvement of inadequate hepcidin secretion against iron overload after HCV eradication. Downregulation of ERFE may have affected the improvement of iron metabolism.

Increased Duodenal Iron Absorption through Upregulation of Ferroportin 1 due to the Decrement in Serum Hepcidin in Patients with Chronic Hepatitis C.

Hepatic iron accumulation is generally increased in the chronic hepatitis C (CHC) liver; however, the precise mechanism of such accumulation remains unclear. We evaluated iron absorption from the gastrointestinal tract of patients with CHC and control participants. We measured the expression of a panel of molecules associated with duodenal iron absorption and serum hepcidin levels to determine the mechanism of iron accumulation in the CHC liver. We enrolled 24 patients with CHC and 9 patients with chronic gastritis without Helicobacter pylori infection or an iron metabolism disorder as control participants. An oral iron absorption test (OIAT) was administered which involved a dosage of 100 mg of sodium ferrous citrate. Serum level of hepcidin-25 was measured by liquid chromatography-tandem mass spectrometry. Ferroportin 1 (FPN) mRNA was measured by RT-PCR and FPN protein was analyzed by western blot. Samples were obtained from duodenum biopsy tissue from each CHC patient and control participant. Caco-2/TC7 cells were incubated in Costar transwells (0.4 µm pores). The OIAT showed significantly greater iron absorption in CHC patients than control participants. Serum hepcidin-25 in the CHC group was significantly lower than in the control group. Compared with control participants, duodenal FPN mRNA expression in CHC patients was significantly upregulated. The FPN mRNA levels and protein levels increased significantly in Caco-2/TC7 cell monolayers cultured in transwells with hepcidin. Lower serum hepcidin-25 levels might upregulate not only FPN protein expression but also mRNA expression in the duodenum and cause iron accumulation in patients with CHC.

Relationship between Hepatitis C Virus Infection and Iron Overload.

OBJECTIVE: The aim of this study was to summarize the interactions between hepatitis C virus (HCV) infection and iron overload, and to understand the mechanisms of iron overload in chronic hepatitis C (CHC) and the role iron plays in HCV life cycle. DATA SOURCES: This review was based on data in articles published in the PubMed databases up to January 28, 2017, with the keywords "hepatitis C virus", "iron overload", "iron metabolism", "hepcidin", "translation", and "replication". STUDY SELECTION: Articles related to iron metabolism, iron overload in patients with CHC, or the effects of iron on HCV life cycle were selected for the review. RESULTS: Iron overload is common in patients with CHC. The mechanisms involve decreased hepcidin levels caused by HCV through signal transducer and activator of transcription 3, mitogen-activated protein kinase, or bone morphogenetic protein/SMAD signaling pathways, and the altered expression of other iron-metabolism-related genes. Some studies found that iron increases HCV replication, while other studies found the opposite result. Most of the studies suggest the positive role of iron on HCV translation, the mechanisms of which involve increased expression levels of factors associated with HCV internal ribosome entry site-dependent translation, such as eukaryotic initiation factor 3 and La protein. CONCLUSION: The growing literature demonstrates that CHC leads to iron overload, and iron affects the HCV life cycle in turn. Further research should be conducted to clarify the mechanism involved in the complicated interaction between iron and HCV.

Protein alteration of HepG2.2.15 cells induced by iron overload.

Hepatitis B can progress into hepatocellular carcinoma. Body irons may interfere with the clearance of hepatitis B virus (HBV) and contribute to genesis of tumor. To investigate the role of iron played in HBV-related pathogenesis, here we studied the effect of iron with different concentrations and valence states on growth of HepG2.2.15 cells and secretion of virus proteins. A strong tolerance of HepG2.2.15 cells to iron challenge was found. The concentration of hepatitis B surface antigen in cell culture medium was decreased after iron stimulation. Lower concentrations of iron facilitated hepatitis B e-antigen (HBeAg) secretion. Fe(2+) appeared more effective on HBeAg secretion than Fe(3+) did. In parallel, the differential protein profiles in HepG2.2.15 cells were studied by iTRAQ and LC-MS/MS. The differentially expressed proteins were mainly involved in stress response, signal transduction, apoptosis, etc. Four proteins (14-3-3 ß/α, VCP, migration inhibitory factor, and Nup153) were verified by Western-blotting and found to be consistent with the iTRAQ data. Interestingly, nuclear import of Nuclear factor kappa B (NFκB) and its activity were found to be affected by the decreased Nup153 in iron stimulated HepG2.2.15 cells. The results may indicate possible molecular mechanism how the synergism of HBV and iron stimulation damages host liver cells.

Clinical impact of HFE mutations in Japanese patients with chronic hepatitis C.

BACKGROUND AND AIM: HFE mutations, a common cause of hereditary hemochromatosis (HH), are reportedly associated with hepatic iron overload, severe liver fibrosis, and good response to interferon treatment in European patients with chronic hepatitis C (CHC). HH shows ethnicity-based differences and little is known about the effects of HH mutations on CHC in the Japanese. Thus, the aim of this study was to clarify the clinical influence of HFE mutations in Japanese CHC patients. METHODS: In a total of 251 patients with CHC, we analyzed the frequencies of H63D and S65C mutations in the HFE gene, and the influence of these mutations on clinical parameters and response to pegylated-interferon-alpha 2b (PEG-IFN) plus ribavirin therapy. RESULTS: Fourteen patients (5.6%) carried the H63D mutation; all were heterozygotes. No S65C mutations were found. Only hemoglobin levels in the H63D heterozygotes were higher than in wild-type patients. Eleven of 14 H63D heterozygotes achieved sustained virological response (SVR). On univariate analysis, factors associated with SVR were interleukin 28B (IL28B) polymorphism, age, hepatitis C virus (HCV) genotype, HCV viral load, white blood cell count, stage of fibrosis and H63D mutation. All patients with both TT genotype in IL28B (rs8099917) and H63D mutation in HFE (n = 10) achieved SVR. CONCLUSIONS: The H63D mutation has little impact on the clinical characteristics of CHC, but is related to favorable response to PEG-IFN plus ribavirin therapy, particularly in patients with the TT allele in IL28B.

Hepcidin levels and iron status in beta-thalassemia major patients with hepatitis C virus infection.

Beta-thalassemia is an inherited anemia in which synthesis of the hemoglobin beta-chain is decreased. Clinical features of beta-thalassemia include variably severe anemia and iron overload due to increased intestinal iron absorption, which may result in damage to vital organs. The hepatic peptide; hepcidin is a key regulator of iron metabolism in mammals. The present study aimed to determine the relationship between hepcidin expression and iron status in beta-thalassemia patients with hepatitis C virus infection. The study included 50 patients diagnosed as beta-thalassemia major (21 of them were HCV infected and 29 were HCV negative), in addition, 20 healthy subjects were enrolled in the study. The hepatic iron and hepcidin mRNA concentration in liver biopsy samples were measured, as well as serum ferritin, serum iron, hemoglobin and levels and serum hepcidin. Result showed remarkable decrease of serum and liver hepcidin mRNA expression in thalassemic patients as compared to controls, and showed a positive correlation with hemoglobin concentration, but negatively correlated with serum ferritin level and hepatic iron index (HII). In HCV infected patients, serum and liver hepcidin mRNA were markedly depressed in HCV positive beta-thalassemia cases, and positively correlated serum albumin and prothrombin concentrations, but inversely correlated with HII and fibrosis score. In HCV positive beta-thalassemia major patients, the hepcidin mRNA level was positively correlated with the synthetic function of the liver (namely serum albumin and prothrombin concentration) and with serum hepcidin level. While, both serum and hepcidin mRNA level was inversely correlated with HII and fibrosis score in these patients. These results suggest a possible role of hepcidin expression in iron overload in beta-thalassemia major, consequent disease progression and development of liver fibrosis.

Hepatic iron accumulation is associated with disease progression and resistance to interferon/ribavirin combination therapy in chronic hepatitis C.

BACKGROUND AND AIMS: Liver iron accumulation in patients with chronic hepatitis C (CHC) has received increasing attention in recent years. The aim of this study was to determine the prevalence and severity of liver iron deposition in CHC, to assess its relationship with clinical, biochemical and histological characteristics, and to study its influence on the response to interferon (IFN) plus ribavirin combination therapy. METHODS: We studied liver biopsy specimens from 103 hepatitis C virus (HCV) and 34 hepatitis B virus (HBV) infected patients and total iron score (TIS) was measured. Seventy patients infected with HCV genotype 1b were treated with IFN/ribavirin for 24 weeks. RESULTS: CHC patients had a significantly higher TIS than chronic hepatitis B (CHB) patients (7.03 +/- 5.34 vs 4.41 +/- 4.49, P = 0.0056). TIS was significantly correlated with alcohol intake (P = 0.0213, r = 0.290), transaminase level (P = 0.0126, r = 0.247), platelet count (P = 0.0002, r = -0.369), histological grading (P = 0.0121, r = 0.248) and staging (P = 0.0003, r = 0.356) in CHC patients. Pretreatment TIS was significantly higher in non-sustained virological responders (SVR) than in SVR to IFN/ribavirin treatment (TIS = 7.69 +/- 5.76 vs 4.39 +/- 3.27, P = 0.0310). Multiple regression analysis showed that TIS was the only independent variable associated with resistance to IFN/ribavirin (P = 0.0277). CONCLUSIONS: Liver iron deposition was common in CHC compared to CHB and was associated with liver disease progression. Increased hepatic iron stores in CHC were related to resistance to IFN/ribavirin treatment.

Relative contribution of iron genes, dysmetabolism and hepatitis C virus (HCV) in the pathogenesis of altered iron regulation in HCV chronic hepatitis.

BACKGROUND AND OBJECTIVES: Hepatitis C virus (HCV) chronic hepatitis predisposes to iron overload, which negatively influences the prognosis of this infection. Since the underlying mechanisms of this iron overload are undefined, we analyzed the prevalence of altered iron parameters, and the relative contribution of viral, metabolic, and genetic factors in Italian patients. DESIGN AND METHODS: We studied the metabolic and biochemical characteristics of 143 previously untreated, biopsied patients with HCV who were not alcohol abusers. Hepatic iron was determined according to Deugnier, HFE genotype by restriction analysis, hepcidin, hemojuvelin, ferroportin-1, and transferrin receptor-2 mutations by denaturing high performance liquid chromatography and sequencing. RESULTS: Increased transferrin saturation was observed in 20%, hyperferritinemia in 22%, and histological iron deposition in 32% of patients. Ferritin was independently correlated with iron stores and host metabolic parameters, whereas hepatic iron deposition was correlated with ferritin and histological severity of hepatitis. Sinusoidal iron deposition was associated with metabolic alterations, including body mass index, insulin resistance, and LDL cholesterol. Conversely, the prevalence of HFE mutations and serum ferritin values increased with the severity of steatosis. The prevalence of HFE and beta-globin mutations was not different from that of controls (31% and 2%, respectively). No tranferrin receptor-2, hemojuvelin, or ferroportin-1 mutations were detected, but two patients carried the -72C>T hepcidin promoter mutation. The C282Y HFE mutation, hepcidin and beta-globin mutations influenced iron stores. Both carriers of the -72C>T Hepcidin mutation had beta-thalassemia trait, moderate iron overload, and liver cirrhosis. INTERPRETATION AND CONCLUSIONS: Iron genes influence iron overload and steatosis development, but the major burden is related to HCV itself and host metabolic factors.

Heterozygous beta-globin gene mutations as a risk factor for iron accumulation and liver fibrosis in chronic hepatitis C.

BACKGROUND: Iron accumulation is a well-known risk factor for the progression of chronic hepatitis C (CHC) to fibrosis. However, the profibrogenic role of the genes controlling iron homeostasis is still controversial. AIM: To evaluate the relative role of haemachromatosis (HFE), ferroportin and beta-globin gene mutations in promoting iron accumulation and fibrosis in patients with CHC. METHODS: Genetic analysis was performed together with the assessment of hepatic iron content and histology in 100 consecutive HIV-antibody and hepatitis B surface antigen-negative patients with biopsy-proven CHC. RESULTS: Among the patients investigated, 12 were heterozygous for various beta-globin gene mutations (39[C-->T], IVS1.1[G-->A], 22 7 bp deletion and IVS1.6[T-->C]) and 29 carried HFE (C282Y, H63D and S65C) gene mutations. One further patient was heterozygous for both HFE (H63D) and beta-globin (39[C-->T]) variants, whereas 58 had the wild-type alleles of both the genes. Hepatic iron concentration (HIC) and hepatic stainable iron were significantly higher (p<0.05) in patients with CHC carrying beta-globin mutations than in those with HFE mutations or the wild-type alleles. Multivariate analysis confirmed that the presence of beta-globin mutations was independently associated with both HIC (p = 0.008) and hepatic-stainable iron (odds ratio (OR) 6.11; 95% CI 1.56 to 23.92; p = 0.009). Moderate/severe fibrosis or cirrhosis (Ishak's score >2) was observed in 48 of 100 patients. Logistic regression demonstrated that age (OR 1.05; 95% CI 1.02 to 1.09; p<0.005) and beta-globin mutations (OR 4.99; 95% CI 1.22 to 20.3; p = 0.025) were independent predictors of the severity of fibrosis. CONCLUSIONS: Heterozygosis for beta-globin mutations is a novel risk factor for both hepatic iron accumulation and the progression to fibrosis in patients with CHC.

Role of hemochromatosis genes in chronic hepatitis C.

PURPOSE: Hereditary hemochromatosis is commonly associated with iron overload and hepatitis C virus (HCV). Association between hemochromatosis C282Y or H63D mutation has been observed, although not uniformly, and iron overload is also commonly found in chronic HCV hepatitis. This study explored the contribution of genetic hemochromatosis to iron accumulation in hepatitis C. DESIGN: Review of current literature. RESULTS: The prevalence of increased serum iron stores in patients with HCV infection is 28% (patients having an elevated ferritin or transferrin saturation). Patients with elevated serum iron markers have more active chronic hepatitis with more liver fibrosis. In the opinion of the experts HFE mutations are not associated with a high hepatic iron content. No relation was detected between hepatic iron stores and HFE gene mutation. Significant iron deposition in the liver was uncommon and overall the quantity of iron that was detectable histologically and biochemically was unrelated to the grade and stage of HCV related liver injury. The mechanism by which liver iron accumulates in patients is unclear. CONCLUSIONS: Carriage of HFE mutations does not have a role in the accumulation of iron or the liver disease in HCV. These findings do not support a role for iron depletion in patients with chronic HCV infection, including these with elevated serum studies.

Benign coxsackievirus damages heart muscle in iron-loaded vitamin E-deficient mice.

Several oxidative stressors (dietary selenium deficiency, dietary vitamin E deficiency coupled with fish oil feeding, genetic reduction of glutathione peroxidase activity) allow a normally benign coxsackievirus B3 (CVB3/0) to damage heart muscle in host mice. This study investigated whether dietary iron overload, another oxidant stress, would also permit CVB3/0 to exert a cardiopathologic effect in vitamin E-deficient (-VE) mice. Four groups of mice were fed either a -VE or a +VE diet containing either an adequate or an excessive (30x) amount of iron. After 4 weeks of feeding, the mice were inoculated with CVB3/0 and heart damage was assessed at various times postinfection. Mice fed a diet sufficient in VE with excess iron developed heart damage equivalent to mice fed a diet deficient in vitamin E without excess iron. However, severe heart damage occurred in the group fed a diet deficient in VE with excess iron, which was the most pro-oxidative diet. The highest heart viral titers were found in mice fed the -VE/excessive iron diet. However, the extent of heart damage did not always correlate with the formation of TBARS in liver homogenates. Further research is needed to clarify the role of oxidative stress and iron overload in determining the course of viral infection.

HCV and HGV infection, iron overload and liver disease in multitransfused patients with thalassaemia and persistently normal or abnormal transaminase levels.

Prevalence and influence on liver disease of HCV and HGV infections, and HCV genotypes were studied in 28 HCV-Ab positive multitransfused thalassaemia patients with persistently normal ALT levels (group A) matched by sex and age with 28 patients with increased ALT levels (group B). Laboratory and virologic tests (all patients), liver biopsy (28 patients) and LIC by SQUID (30 patients) were performed. In group A, HCV-RNA was positive in 39%, genotype 2a was detected in 91%. In Group B, HCV-RNA was positive in 89%, prevalence of genotype 1b and 2a was 52% and 48% respectively; compared with group A, they had significantly increased values of gammaGT, AF, BA, TP, IgG, IgA, LIC (group B: 2,142 -/+ 1,524 microg/g liver; group A: 1,084 -/+ 610 microg/g liver). Overall prevalence of HGV-RNA was low (12.5%) and not significantly different between groups. Liver biopsies revealed no cirrhosis and severe fibrosis was found in 3 HCV viremic patients in group B. In 14 viremic patients examined both for LIC and liver histology, mild fibrosis was observed in 71%, in which iron overload was below 5 times the normal value. In conclusion, in patients with normal ALT levels, active HCV infection must be excluded by evaluation of HCV-RNA. Liver biopsy is indicated in HCV viremic patients, independent of ALT levels; in non-viremic patients, increased ALT levels may be due to iron overload and LIC measurement is indicated. Our data emphasise the crucial role of chelation therapy to maintain low LIC levels in order to prevent progression of fibrosis to cirrhosis in patients with HCV chronic hepatitis.

Hemochromatosis and transferrin receptor gene polymorphisms in chronic hepatitis C: impact on iron status, liver injury and HCV genotype.

Mild iron overload in chronic hepatitis C is associated with liver fibrosis, hepatitis C virus (HCV) genotype 1b infection, and an impaired response to interferon therapy. In this study we evaluated whether polymorphisms in the hemochromatosis gene HFE and the transferrin receptor gene TFR1 are associated with these typical findings. The study considered 246 HCV-infected patients and 200 blood donors as controls, in which C282Y, H63D, and S65C mutations ( HFE) and the S142G polymorphism ( TFR1) were detected. HCV genotype, serum ferritin levels, stainable intrahepatic iron, and grade of fibrosis according to the METAVIR score (F0-F4) were determined. In HCV-infected patients, heterozygosity for the C282Y mutation in HFE was significantly associated with elevated serum ferritin levels, stainable liver iron, and advanced fibrosis or cirrhosis (F2-F4). By multivariate logistic regression analysis the odds ratio for the development of advanced fibrosis or cirrhosis (F2-F4) was 2.5 for HCV-infected patients carrying a heterozygous C282Y mutation and 4.8 for HCV-infected patients with C282Y/H63D and C282Y/S65C compound heterozygosity. Heterozygosity for the C282Y mutation in HFE contributes to iron accumulation and fibrosis progression in chronic hepatitis C.

Commentary: Iron metabolism in hepatitis C infection.

Hepatitis C virus (HCV) infections have started to decline, but up to 10,000 deaths each year are the consequence of chronic liver disease, following the infection. Laboratory testing identifies HCV-infected individuals using positive recombinant immunoblot assays to detect the presence of the antibody; the diagnosis is confirmed by detecting HCV RNA in serum. HCV-infected patients who have large accumulations of hepatic iron have not responded well to interferon therapy, compared to patients with normal hepatic iron stores. Physicians who treat patients infected with HCV should be aware of the detrimental effect of excess liver iron on interferon therapy. The degree of hepatic iron overload should be assessed and the reason for the excess iron should be investigated. Phlebotomy is the most practical method for iron removal and is well tolerated by patients with HCV infection.