Iron, haemochromatosis and thalassaemia as risk factors for fibrosis in hepatitis C virus infection

Iron Dyshomeostasis in COVID-19: Biomarkers Reveal a Functional Link to 5-Lipoxygenase Activation

Coronavirus disease 2019 (COVID-19) is characterized by a broad spectrum of clinical symptoms. After acute infection, some subjects develop a post-COVID-19 syndrome known as long-COVID. This study aims to recognize the molecular and functional mechanisms that occur in COVID-19 and long-COVID patients and identify useful biomarkers for the management of patients with COVID-19 and long-COVID. Here, we profiled the response to COVID-19 by performing a proteomic analysis of lymphocytes isolated from patients. We identified significant changes in proteins involved in iron metabolism using different biochemical analyses, considering ceruloplasmin (Cp), transferrin (Tf), hemopexin (HPX), lipocalin 2 (LCN2), and superoxide dismutase 1 (SOD1). Moreover, our results show an activation of 5-lipoxygenase (5-LOX) in COVID-19 and in long-COVID possibly through an iron-dependent post-translational mechanism. Furthermore, this work defines leukotriene B4 (LTB4) and lipocalin 2 (LCN2) as possible markers of COVID-19 and long-COVID and suggests novel opportunities for prevention and treatment.

The Toxic Influence of Excess Free Iron on Red Blood Cells in the Biophysical Experiment: An In Vitro Study

Iron is needed for life-essential processes, but free iron overload causes dangerous clinical consequences. The study of the role of red blood cells (RBCs) in the influence of excess free iron in the blood on the pathological consequences in an organism is relevant. Here, in a direct biophysical experiment in vitro, we studied the action of free iron overload on the packed red blood cell (pRBC) characteristics. In experiments, we incubated pRBCs with the ferrous sulfate solution (Fe²⁺). Wе used free iron in a wide range of concentrations. High Fe²⁺ concentrations made us possible to establish the pattern of the toxic effect of excess iron on pRBCs during a reduced incubation time in a biophysical experiment in vitro. It was found that excess free iron causes changes in pRBC morphology, the appearance of bridges between cells, and the formation of clots, increasing the membrane stiffness and methemoglobin concentration. We created a kinetic model of changes in the hemoglobin derivatives. The complex of simultaneous distortions of pRBCs established in our experiments can be taken into account when studying the mechanism of the toxic influence of excess free iron in the blood on pathological changes in an organism.

Tocilizumab Treatment Effect on Iron Homeostasis in Severe COVID-19 Patients

Background

Tocilizumab has been proposed as an effective treatment for severe COVID-19. We aimed to investigate whether tocilizumab administration is associated with increased availability of serum iron which may possibly be associated with adverse effects on clinical outcomes.

Methods

We performed an observational, retrospective cohort study. We included adults, who were hospitalized in ICU with the diagnosis of severe COVID-19 infection eligible for tocilizumab treatment. Laboratory data including serum iron, ferritin, transferrin saturation, hemoglobin, and C-reactive protein levels of all patients were collected shortly before and 24 h, 48 h, and 72 h after tocilizumab administration.

Results

During the study period, 15 patients fulfilled the inclusion criteria and were eligible to receive tocilizumab treatment. Tocilizumab therapy was associated with a prominent increase in serum iron and transferrin saturation levels (26 ± 13 μg/dL and 15 ± 8% before treatment and 79 ± 32 μg/dL and 41 ± 15% 72 h after treatment, respectively, p < 0.001) and decrease in serum ferritin levels (1,921 ± 2,071 ng/mL before and 1,258 ± 1,140 ng/mL 72 h after treatment, p = 0.027).

Conclusion

Treatment of severe COVID-19 patients with tocilizumab is associated with a profound increase in serum iron and ferritin saturation levels along with a decrease in ferritin levels. This may represent an undesirable side effect that may potentiate viral replication.

COVID-19 as part of the hyperferritinemic syndromes: the role of iron depletion therapy

SARS-CoV-2 infection is characterized by a protean clinical picture that can range from asymptomatic patients to life-threatening conditions. Severe COVID-19 patients often display a severe pulmonary involvement and develop neutrophilia, lymphopenia, and strikingly elevated levels of IL-6. There is an over-exuberant cytokine release with hyperferritinemia leading to the idea that COVID-19 is part of the hyperferritinemic syndrome spectrum. Indeed, very high levels of ferritin can occur in other diseases including hemophagocytic lymphohistiocytosis, macrophage activation syndrome, adult-onset Still's disease, catastrophic antiphospholipid syndrome and septic shock. Numerous studies have demonstrated the immunomodulatory effects of ferritin and its association with mortality and sustained inflammatory process. High levels of free iron are harmful in tissues, especially through the redox damage that can lead to fibrosis. Iron chelation represents a pillar in the treatment of iron overload. In addition, it was proven to have an anti-viral and anti-fibrotic activity. Herein, we analyse the pathogenic role of ferritin and iron during SARS-CoV-2 infection and propose iron depletion therapy as a novel therapeutic approach in the COVID-19 pandemic.

COVID-19 as part of the hyperferritinemic syndromes: the role of iron depletion therapy

SARS-CoV-2 infection is characterized by a protean clinical picture that can range from asymptomatic patients to life-threatening conditions. Severe COVID-19 patients often display a severe pulmonary involvement and develop neutrophilia, lymphopenia, and strikingly elevated levels of IL-6. There is an over-exuberant cytokine release with hyperferritinemia leading to the idea that COVID-19 is part of the hyperferritinemic syndrome spectrum. Indeed, very high levels of ferritin can occur in other diseases including hemophagocytic lymphohistiocytosis, macrophage activation syndrome, adult-onset Still's disease, catastrophic antiphospholipid syndrome and septic shock. Numerous studies have demonstrated the immunomodulatory effects of ferritin and its association with mortality and sustained inflammatory process. High levels of free iron are harmful in tissues, especially through the redox damage that can lead to fibrosis. Iron chelation represents a pillar in the treatment of iron overload. In addition, it was proven to have an anti-viral and anti-fibrotic activity. Herein, we analyse the pathogenic role of ferritin and iron during SARS-CoV-2 infection and propose iron depletion therapy as a novel therapeutic approach in the COVID-19 pandemic.

Depriving Iron Supply to the Virus Represents a Promising Adjuvant Therapeutic Against Viral Survival

PURPOSE OF THE REVIEW

The ongoing outbreak of novel coronavirus pneumonia (COVID-19) caused by the 2019 novel coronavirus (SARS-CoV-2) in China is lifting widespread concerns. Thus, therapeutic options are urgently needed, and will be discussed in this review.

RECENT FINDINGS

Iron-containing enzymes are required for viruses most likely including coronaviruses (CoVs) to complete their replication process. Moreover, poor prognosis occurred in the conditions of iron overload for patients upon infections of viruses. Thus, limiting iron represents a promising adjuvant strategy in treating viral infection through oral uptake or venous injection of iron chelators, or through the manipulation of the key iron regulators. For example, treatment with iron chelator deferiprone has been shown to prolong the survival of acquired immunodeficiency syndrome (AIDS) patients. Increasing intracellular iron efflux via increasing iron exporter ferroportin expression also exhibits antiviral effect on human immunodeficiency virus (HIV). The implications of other metals besides iron are also briefly discussed.

SUMMARY

For even though we know little about iron regulation in COVID-19 patients thus far, it could be deduced from other viral infections that iron chelation might be an alternative beneficial adjuvant in treating COVID-19.

Human Leukocyte Antigen (HLA) and Immune Regulation: How Do Classical and Non-Classical HLA Alleles Modulate Immune Response to Human Immunodeficiency Virus and Hepatitis C Virus Infections?

The genetic factors associated with susceptibility or resistance to viral infections are likely to involve a sophisticated array of immune response. These genetic elements may modulate other biological factors that account for significant influence on the gene expression and/or protein function in the host. Among them, the role of the major histocompatibility complex in viral pathogenesis in particular human immunodeficiency virus (HIV) and hepatitis C virus (HCV), is very well documented. We, recently, added a novel insight into the field by identifying the molecular mechanism associated with the protective role of human leukocyte antigen (HLA)-B27/B57 CD8⁺ T cells in the context of HIV-1 infection and why these alleles act as a double-edged sword protecting against viral infections but predisposing the host to autoimmune diseases. The focus of this review will be reexamining the role of classical and non-classical HLA alleles, including class Ia (HLA-A, -B, -C), class Ib (HLA-E, -F, -G, -H), and class II (HLA-DR, -DQ, -DM, and -DP) in immune regulation and viral pathogenesis (e.g., HIV and HCV). To our knowledge, this is the very first review of its kind to comprehensively analyze the role of these molecules in immune regulation associated with chronic viral infections.

AMPK activation by isorhamnetin protects hepatocytes against oxidative stress and mitochondrial dysfunction

Arachidonic acid (AA) is a ω-6 polyunsaturated fatty acid that is found in the phospholipids of membranes and released from the cellular membrane lipid bilayer by phospholipase A2. During this process, AA could produce excess reactive oxygen species and induce apoptosis and mitochondrial dysfunction by selectively inhibiting complexes I and III. Isorhamnetin, an O-methylated flavonol aglycone, has been shown to have cardio-protective, anti-adipogenic, anti-tumor, and anti-inflammatory effects. In the present study, we investigated the effects of isorhamnetin on hepatotoxicity and the underlying mechanisms involved. Our in vitro experiments showed that isorhamnetin dose-dependently blocked the hepatotoxicity induced by treatment with AA plus iron in HepG2 cells. Furthermore, isorhamnetin inhibited the AA+iron induced generation of reactive oxygen species and reduction of glutathione, and subsequently maintained mitochondria membrane potential in AA+iron treated HepG2 cells. In addition, isorhamnetin activated AMP-activated protein kinase (AMPK) by Thr-172 phosphorylation of AMPKα, and this was mediated with Ca2+/calmodulin-dependent protein kinase kinase-2 (CaMKK2), but not liver kinase B1. Experiments using CaMKK2 siRNA or its selective inhibitor, STO-609, revealed the role of CaMKK2 in the isorhamnetin-induced activation of AMPK in HepG2 cells. These results indicate isorhamnetin protects against the hepatotoxic effect of AA plus iron, and suggest that the AMPK pathway is involved in the mechanism underlying the beneficial effect of isorhamnetin in the liver.

Iron metabolic disorder in chronic hepatitis C: mechanisms and relevance to hepatocarcinogenesis

The liver is the major iron storage organ in the body, and therefore, iron metabolic disorder is sometimes involved in chronic liver diseases. Chronic hepatitis C is one of the liver diseases that show hepatic iron accumulation, even though its level should be recognized to be basically mild to moderate and sometimes within the normal range. The mechanisms underlying hepatic iron accumulation in chronic hepatitis C have not been fully elucidated. Reduction of the hepcidin transcription activity by hepatitis C virus (HCV)-induced reactive oxygen species may in part account for it, but the regulation of hepcidin is very complex and may depend on many variables, including the particular stage of the systemic and/or hepatic inflammatory conditions and the circulating transferrin-bound iron and intracellular iron stores. This might explain the variations in hepatic iron concentrations reported among patients with HCV-related chronic liver disease. However, even mild-to-moderate iron overload in the liver contributes to disease progression and hepatocarcinogenesis in chronic hepatitis C probably by reinforcing the HCV-induced oxidative stress through Fenton reaction. The present review highlights the current concept of hepatic iron overload status in chronic hepatitis C and discusses how iron metabolic disorder develops in this disease and the impact of hepatic iron overload on disease progression and its relevance to hepatocarcinogenesis.

Effect of antioxidant therapy on hepatic fibrosis and liver iron concentrations in β-thalassemia major patients

To assess the effects of combined vitamin therapy on oxidant-antioxidant hepatic status and hemoglobin (Hb) derivatives on β-thalassemia major (β-TM), a prospective study of 60 β-TM patients aged 4 to 17 years, was conducted. Thirty-nine patients with initial low serum vitamins E, C and A, were treated with oral combined vitamins for 1 year compared to 21 patients with normal vitamin levels. Serum transaminases, serum ferritin, hepatic fibroscan elastography (TE) and magnetic resonance imaging R2* (MRI R2*) for liver iron concentration (LIC), were assessed before and after 6 and 12 months of therapy. Antioxidant capacity was assessed by levels of reduced glutathione (GSH), malondialdehyde (MDA), catalase, superoxide dismutase and GSH enzymes. The studied vitamins, reduced GSH and Hb levels were significantly elevated and paralleled by progressive decline in MDA and ferritin during therapy (p <0.001). Serum transaminase and superoxide dismutase were significantly decreased, while GSH reductase was significantly elevated during therapy (p <0.001). Improvement of hepatic fibrosis as 23.0% had TE (>12 kPa) at baseline compared to 20.5% after therapy (p >0.05), although LIC values were significantly decreased (p <0.001). Combined vitamin therapy improves the antioxidant/oxidant balance, LIC and hepatic fibrosis in young β-TM patients.

Long-term follow-up of HCV-infected hematopoietic SCT patients and effects of antiviral therapy

This prospective study was initiated in 1993 with the aim to study late effects and responses to antiviral therapy in a cohort of hepatitis C virus (HCV)-infected patients. A total of 195 patients were included from 12 centers. In all, 134 patients had undergone allogeneic and 61 autologous hematopoietic SCT (HSCT). The median follow-up from HSCT is currently 16.8 years and the maximum 27.2 years. Overall 33 of 195 patients have died of which 6 died from liver complications. The survival probability was 81.6% and the cumulative incidence for death in liver complications was 6.1% at 20 years after HSCT. The cumulative incidence of severe liver complications (death from liver failure, cirrhosis and liver transplantation) was 11.7% at 20 years after HSCT. In all, 85 patients have been treated with IFN; 42 in combination with ribavirin. The sustained response rate was 40%. The rates of severe side effects were comparable to other patient populations and no patient developed significant exacerbations of GVHD. Patients receiving antiviral therapy had a trend toward a decreased risk of severe liver complications (odds ratio=0.33; P=0.058). HCV infection is associated with morbidity and mortality in long-term survivors after HSCT. Antiviral therapy can be given safely and might reduce the risk for severe complications.

The role of iron in the pathophysiology and treatment of chronic hepatitis C

Increased hepatic iron content may be observed in patients with chronic hepatitis C infection, and may contribute to disease severity. The presence of hemochromatosis gene mutations is associated with increased hepatic iron accumulation and may lead to accelerated disease progression. Hepatic iron depletion has been postulated to decrease the risk of hepatocellular carcinoma in patients with cirrhosis due to chronic hepatitis C. It is possible that iron depletion stabilizes or improves liver histology and slows disease progression in these individuals. The present article reviews the prevalence and risk factors for hepatic iron overload in chronic hepatitis C, with emphasis on the available data regarding the efficacy of iron depletion in the treatment of this common liver disease.

The role of iron in the pathophysiology and treatment of chronic hepatitis C

Increased hepatic iron content may be observed in patients with chronic hepatitis C infection, and may contribute to disease severity. The presence of hemochromatosis gene mutations is associated with increased hepatic iron accumulation and may lead to accelerated disease progression. Hepatic iron depletion has been postulated to decrease the risk of hepatocellular carcinoma in patients with cirrhosis due to chronic hepatitis C. It is possible that iron depletion stabilizes or improves liver histology and slows disease progression in these individuals. The present article reviews the prevalence and risk factors for hepatic iron overload in chronic hepatitis C, with emphasis on the available data regarding the efficacy of iron depletion in the treatment of this common liver disease.

Regulation of iron absorption in hemoglobinopathies

Beta-thalassemia and sickle cell anemia (SCD) represent the most common hemoglobinopathies caused, respectively, by deficient production or alteration of the beta chain of hemoglobin (Hb). Patients affected by the most severe form of thalassemia suffer from profound anemia that requires chronic blood transfusions and chelation therapies to prevent iron overload. However, patients affected by beta-thalassemia intermedia, a milder form of the disease that does not require chronic blood transfusions, eventually also show elevated body iron content due to increased gastrointestinal iron absorption. Even SCD patients might require blood transfusions and iron chelation to prevent deleterious and painful vaso-occlusive crises and complications due to iron overload. Although definitive cures are presently available, such as bone marrow transplantation (BMT), or are in development, such as correction of the disease through hematopoietic stem cell beta-globin gene transfer, they are potentially hazardous procedures or too experimental to provide consistently safe and predictive clinical outcomes. Therefore, studies that aim to better understand the pathophysiology of the hemoglobinopathies might provide further insight and new drugs to dramatically improve the understanding and current treatment of these diseases. This review will describe how recent discoveries on iron metabolism and erythropoiesis could lead to new therapeutic strategies and better clinical care of these diseases, thereby yielding a much better quality of life for the patients.

Viral infection and iron metabolism

Fundamental cellular operations, including DNA synthesis and the generation of ATP, require iron. Viruses hijack cells in order to replicate, and efficient replication needs an iron-replete host. Some viruses selectively infect iron-acquiring cells by binding to transferrin receptor 1 during cell entry. Other viruses alter the expression of proteins involved in iron homeostasis, such as HFE and hepcidin. In HIV-1 and hepatitis C virus infections, iron overload is associated with poor prognosis and could be partly caused by the viruses themselves. Understanding how iron metabolism and viral infection interact might suggest new methods to control disease.