The effect of iron overload on in vitro HIV-1 infection

Taurolithocholic acid protects against viral haemorrhagic fever via inhibition of ferroptosis

Bile acids are microbial metabolites that can impact infection of enteric and hepatitis viruses, but their functions during systemic viral infection remain unclear. Here we show that elevated levels of the secondary bile acid taurolithocholic acid (TLCA) are associated with reduced fatality rates and suppressed viraemia in patients infected with severe fever with thrombocytopenia syndrome virus (SFTSV), an emerging tick-borne haemorrhagic fever virus. TLCA inhibits viral replication and mitigates host inflammation during SFTSV infection in vitro, and indirectly suppresses SFTSV-mediated induction of ferroptosis by upregulating fatty acid desaturase 2 via the TGR5-PI3K/AKT-SREBP2 axis. High iron and ferritin serum levels during early infection were correlated with decreased TLCA levels and fatal outcomes in SFTSV-infected patients, indicating potential biomarkers. Furthermore, treatment with either ferroptosis inhibitors or TLCA protected mice from lethal SFTSV infection. Our findings highlight the therapeutic potential of bile acids to treat haemorrhagic fever viral infection.

Anemia and Iron Supplementation in Relation to Viral Load and Mortality among 70,442 People Living with Human Immunodeficiency Virus in Tanzania

BACKGROUND

Anemia may be associated with poor clinical outcomes among people living with human immunodeficiency virus (HIV) (PLHIV) despite highly active antiretroviral therapy (HAART). There are concerns that iron supplementation may be unsafe to prevent and treat anemia among PLHIV.

OBJECTIVE

The objective of the study was to evaluate the associations of anemia and iron supplementation with mortality and viral load among PLHIV in Tanzania.

METHODS

We analyzed data from a cohort of 70,442 nonpregnant adult PLHIV in Tanzania conducted between 2015 and 2019. Regression models evaluated the relationships between anemia severity and iron supplement use with mortality and unsuppressed HIV-1 viral load among all participants and stratified by whether participants were initiating or continuing HAART.

RESULTS

Anemia was associated with an increased risk of mortality and unsuppressed viral load for participants who initiated or continued HAART. Iron supplement use was associated with reduced mortality risk but also had a greater risk of an unsuppressed viral load among participants continuing HAART. There was no association of iron supplement use with mortality, and unsuppressed viral load among PLHIV that were initiating HAART. There was a stronger negative association between iron supplement use and the risk of having an unsuppressed viral load among participants with stage III/IV disease compared with stage I/II disease.

CONCLUSIONS

Anemia is associated with increased risk of mortality and unsuppressed viral load, but the benefits and safety of iron supplements appear to differ for those initiating compared with continuing ART as well as by HIV disease severity.

The potential role of ferroptosis in COVID-19-related cardiovascular injury

COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged as a global health threat in 2019. An important feature of the disease is that multiorgan symptoms of SARS-CoV-2 infection persist after recovery. Evidence indicates that people who recovered from COVID-19, even those under the age of 65 years without cardiovascular risk factors such as smoking, obesity, hypertension, and diabetes, had a significantly increased risk of cardiovascular disease for up to one year after diagnosis. Therefore, it is important to closely monitor individuals who have recovered from COVID-19 for potential cardiovascular damage that may manifest at a later stage. Ferroptosis is an iron-dependent form of non-apoptotic cell death characterized by the production of reactive oxygen species (ROS) and increased lipid peroxide levels. Several studies have demonstrated that ferroptosis plays an important role in cancer, ischemia/reperfusion injury (I/RI), and other cardiovascular diseases. Altered iron metabolism, upregulation of reactive oxygen species, and glutathione peroxidase 4 inactivation are striking features of COVID-19-related cardiovascular injury. SARS-CoV-2 can cause cardiovascular ferroptosis, leading to cardiovascular damage. Understanding the mechanism of ferroptosis in COVID-19-related cardiovascular injuries will contribute to the development of treatment regimens for preventing or reducing COVID-19-related cardiovascular complications. In this article, we go over the pathophysiological underpinnings of SARS-CoV-2-induced acute and chronic cardiovascular injury, the function of ferroptosis, and prospective treatment approaches.

A haemochromatosis-causing HFE mutation is associated with SARS-CoV-2 susceptibility in the Czech population

BACKGROUND

Coronavirus disease (COVID-19), which is caused by the SARS-CoV-2 virus, has become a global pandemic. While susceptibility to COVID-19 is subject to several external factors, including hypertension, BMI, and the presence of diabetes, it is also genetically determined to a significant extent. Infectious agents require iron (Fe) for proper functioning. Carriers of mutations resulting in increased iron concentrations are understood to be at increased risk of COVID-19.

METHODS

We examined HFE genotypes associated with hereditary haemochromatosis (rs1800562 and rs1799945 SNPs) in 617 COVID-19 patients (166 asymptomatic, 246 symptomatic and 205 hospitalised survivors) and 2 559 population-based controls.

RESULTS

We found a higher frequency of the minor allele (Tyr282) of the rs1800562 polymorphism (P < 0.002) in patients compared to controls (8.5 % vs 5.5 %). Non-carriers of the minor allele were protected against SARS-Cov-2 infection (OR, 95 %CI; 0.59, 0.42-0.82). The frequency of minor allele carriers was almost identical across asymptomatic, symptomatic, and hospitalised survivors. The rs1799945 variant did not affect disease severity and its occurrence was almost identical in patients and controls (P between 0.58 and 0.84).

CONCLUSIONS

In conclusion, our results indicate that presence of the rs1800562 minor allele, which is associated with hereditary haemochromatosis (thus increased levels of plasma Fe), increases susceptibility to SARS-CoV-2.

Iron supplementation and paediatric HIV disease progression: a cohort study among children receiving routine HIV care in Dar es Salaam, Tanzania

BACKGROUND

Anaemia is common among HIV-infected children and iron supplementation is prescribed routinely for the prevention and management of anaemia among children. Limited evidence suggests iron supplementation may have adverse effects among HIV-infected populations. We aimed to estimate the effect of iron supplement use on mortality, disease progression and haematological outcomes among HIV-infected children in Dar es Salaam, Tanzania.

METHODS

A prospective cohort study was conducted among HIV-infected children (aged 0-14 years) receiving antiretroviral treatment or supportive care between October 2004 and September 2014. Clinical data were recorded on morbidity and vital status, haematological status and prescriptions at each clinical visit. Cox proportional hazards models adjusted for time-varying covariates were used to estimate the association of time-varying iron supplementation on the hazard rate of mortality, HIV disease stage progression, tuberculosis incidence and anaemia and microcytosis persistence.

RESULTS

In all, 4229 children were observed during 149 260 clinic visits for a mean follow-up of 2.9 years. After adjustment for time-varying clinical covariates, time-varying iron supplementation was associated with a 2.87 times higher hazard rate of mortality (95% CI: 1.70, 4.87) and a 1.48 times higher hazard rate of HIV disease stage progression (95% CI: 1.10, 1.98). Iron supplementation was also associated with a lower rate of anaemia persistence (HR = 0.47; 95% CI: 0.37, 0.61). No differences in the association between iron supplementation and clinical outcomes were observed by antiretroviral therapy or anaemia status.

CONCLUSIONS

Iron supplementation may increase the risk of HIV disease stage progression and mortality among HIV-infected children, while reducing the risk of anaemia.

Iron oxide and iron oxyhydroxide nanoparticles impair SARS-CoV-2 infection of cultured cells

Background

Coronaviruses usually cause mild respiratory disease in humans but as seen recently, some human coronaviruses can cause more severe diseases, such as the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the global spread of which has resulted in the ongoing coronavirus pandemic.

Results

In this study we analyzed the potential of using iron oxide nanoparticles (IONPs) coated with biocompatible molecules like dimercaptosuccinic acid (DMSA), 3-aminopropyl triethoxysilane (APS) or carboxydextran (FeraSpin™ R), as well as iron oxyhydroxide nanoparticles (IOHNPs) coated with sucrose (Venofer^®), or iron salts (ferric ammonium citrate -FAC), to treat and/or prevent SARS-CoV-2 infection. At non-cytotoxic doses, IONPs and IOHNPs impaired virus replication and transcription, and the production of infectious viruses in vitro, either when the cells were treated prior to or after infection, although with different efficiencies. Moreover, our data suggest that SARS-CoV-2 infection affects the expression of genes involved in cellular iron metabolism. Furthermore, the treatment of cells with IONPs and IOHNPs affects oxidative stress and iron metabolism to different extents, likely influencing virus replication and production. Interestingly, some of the nanoparticles used in this work have already been approved for their use in humans as anti-anemic treatments, such as the IOHNP Venofer^®, and as contrast agents for magnetic resonance imaging in small animals like mice, such as the FeraSpin™ R IONP.

Conclusions

Therefore, our results suggest that IONPs and IOHNPs may be repurposed to be used as prophylactic or therapeutic treatments in order to combat SARS-CoV-2 infection.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01542-2.

Iron Overload in Chronic Kidney Disease: Less Ferritin, More T2*MRI

To date, there is no consensus on the most reliable marker of iron status in patients with chronic kidney disease (CKD). Serum ferritin is used routinely, although it may be a misleading marker for iron overload. The success of T2^* MRI in monitoring iron overload in patients with hemoglobinopathies can be beneficial to monitoring patients with CKD.

SARS-CoV-2 Infection Induces Ferroptosis of Sinoatrial Node Pacemaker Cells

BACKGROUND

Increasing evidence suggests that cardiac arrhythmias are frequent clinical features of coronavirus disease 2019 (COVID-19). Sinus node damage may lead to bradycardia. However, it is challenging to explore human sinoatrial node (SAN) pathophysiology due to difficulty in isolating and culturing human SAN cells. Embryonic stem cells (ESCs) can be a source to derive human SAN-like pacemaker cells for disease modeling.

METHODS

We used both a hamster model and human ESC (hESC)-derived SAN-like pacemaker cells to explore the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on the pacemaker cells of the heart. In the hamster model, quantitative real-time polymerase chain reaction and immunostaining were used to detect viral RNA and protein, respectively. We then created a dual knock-in SHOX2:GFP;MYH6:mCherry hESC reporter line to establish a highly efficient strategy to derive functional human SAN-like pacemaker cells, which was further characterized by single-cell RNA sequencing. Following exposure to SARS-CoV-2, quantitative real-time polymerase chain reaction, immunostaining, and RNA sequencing were used to confirm infection and determine the host response of hESC-SAN-like pacemaker cells. Finally, a high content chemical screen was performed to identify drugs that can inhibit SARS-CoV-2 infection, and block SARS-CoV-2-induced ferroptosis.

RESULTS

Viral RNA and spike protein were detected in SAN cells in the hearts of infected hamsters. We established an efficient strategy to derive from hESCs functional human SAN-like pacemaker cells, which express pacemaker markers and display SAN-like action potentials. Furthermore, SARS-CoV-2 infection causes dysfunction of human SAN-like pacemaker cells and induces ferroptosis. Two drug candidates, deferoxamine and imatinib, were identified from the high content screen, able to block SARS-CoV-2 infection and infection-associated ferroptosis.

CONCLUSIONS

Using a hamster model, we showed that primary pacemaker cells in the heart can be infected by SARS-CoV-2. Infection of hESC-derived functional SAN-like pacemaker cells demonstrates ferroptosis as a potential mechanism for causing cardiac arrhythmias in patients with COVID-19. Finally, we identified candidate drugs that can protect the SAN cells from SARS-CoV-2 infection.

Targetting ferroptosis for blood cell-related diseases

Ferroptosis is an iron-dependent cell death pathway and participates in various diseases. Current evidence suggests that ferroptosis can obviously affect the function of blood cells. This paper aims to elaborate the role of ferroptosis in blood cells and related diseases. First, abnormal ferroptosis damages the developing red blood cells by breaking systemic iron homeostasis, leading to erythropoiesis suppression and anaemia. Ferroptosis mediates neutrophils recruitment and neutrophil extracellular trap formation (NETosis). In T-cells, ferroptosis induces a novel point of synergy between immunotherapy and radiotherapy. Additionally, ferroptosis may mediate B cells differentiation, antibody responses and lymphoma. Nevertheless, increased ferroptosis can ameliorate acute myeloid leukaemia and T-cell leukaemia/lymphoma by inducing iron-dependent cancer cells death. Besides, ferroptosis activates platelets by increasing P-selectin, thus causing thromboembolism. Ferroptosis mediates virus infection and parasite infection by driving T-cell death and preventing T-cell immunity. Interestingly, ferroptosis is also considered as a critical player in COVID-19 infections, while targetting ferroptosis may also improve thromboembolism and prognosis in patients with COVID-19 infection. Overall, the crucial role of ferroptosis in blood cells will show a new therapeutic potential in blood cell-related diseases.HighlightsFerroptosis shows a new therapeutic potential for blood cell-related diseases.Ferroptosis damages erythropoiesis and thus induces anaemia.Ferroptosis induces platelet activation and leads to thromboembolism.Ferroptosis regulates T-cell and B-cell immunity, which participant in infectious diseases.Inversely, ferroptosis ameliorates acute myeloid leukaemia and T-cell leukaemia.

The lysosome as a master regulator of iron metabolism

Intracellular iron fulfills crucial cellular processes, including DNA synthesis and mitochondrial metabolism, but also mediates ferroptosis, a regulated form of cell death driven by lipid-based reactive oxygen species (ROS). Beyond their established role in degradation and recycling, lysosomes occupy a central position in iron homeostasis and integrate metabolic and cell death signals emanating from different subcellular sites. We discuss the central role of the lysosome in preserving iron homeostasis and provide an integrated outlook of the regulatory circuits coupling the lysosomal system to the control of iron trafficking, interorganellar crosstalk, and ferroptosis induction. We also discuss novel studies unraveling how deregulated lysosomal iron-handling functions contribute to cancer, neurodegeneration, and viral infection, and can be harnessed for therapeutic interventions.

SARS-CoV-2 Neuronal Invasion and Complications: Potential Mechanisms and Therapeutic Approaches

Clinical reports suggest that the coronavirus disease-19 (COVID-19) pandemic caused by severe acute respiratory syndrome (SARS)-coronavirus-2 (CoV-2) has not only taken millions of lives, but has also created a major crisis of neurologic complications that persist even after recovery from the disease. Autopsies of patients confirm the presence of the coronaviruses in the CNS, especially in the brain. The invasion and transmission of SARS-CoV-2 in the CNS is not clearly defined, but, because the endocytic pathway has become an important target for the development of therapeutic strategies for COVID-19, it is necessary to understand endocytic processes in the CNS. In addition, mitochondria and mechanistic target of rapamycin (mTOR) signaling pathways play a critical role in the antiviral immune response, and may also be critical for endocytic activity. Furthermore, dysfunctions of mitochondria and mTOR signaling pathways have been associated with some high-risk conditions such as diabetes and immunodeficiency for developing severe complications observed in COVID-19 patients. However, the role of these pathways in SARS-CoV-2 infection and spread are largely unknown. In this review, we discuss the potential mechanisms of SARS-CoV-2 entry into the CNS and how mitochondria and mTOR pathways might regulate endocytic vesicle-mitochondria interactions and dynamics during SARS-CoV-2 infection. The mechanisms that plausibly account for severe neurologic complications with COVID-19 and potential treatments with Food and Drug Administration-approved drugs targeting mitochondria and the mTOR pathways are also addressed.

SARS-CoV-2 infection: can ferroptosis be a potential treatment target for multiple organ involvement?

Since the outbreak of the new coronavirus in 2019 (SARS-CoV-2), many studies have been performed to better understand the basic mechanisms and clinical features of the disease. However, uncertainties of the underlying mechanisms of multiple organ involvement remain. A substantial proportion of severe coronavirus disease 2019 (COVID-19) patients have lymphopenia, low serum iron levels, and multiple organ involvement. Several therapeutic agents have been used for different stages of the disease, but the treatment for severe disease is still suboptimal. Understanding the mechanism of programmed cell death in COVID-19 may lead to better therapeutic strategies for these patients. On the basis of observations of basic science studies and clinical researches on COVID-19, we hypothesize that ferroptosis, a novel programmed cell death, may be an important cause of multiple organ involvement in COVID-19 and it might serve as a new treatment target. In spite of the existing findings on the involvement of ferroptosis in SARS-CoV-2 infection, there is no reported study to uncover how does ferroptosis acts in SARS-CoV-2 infection yet. Uncovering the role of ferroptosis in SARS-CoV-2 infection is essential to develop new treatment strategies for COVID-19. Intracellular cell iron depletion or new generation of ferroptosis inhibitors might be potential drug candidates for COVID-19. We hope this hypothesis may launch a new wave of studies to uncover the association of ferroptosis and SARS-CoV-2 infection in vitro and in vivo.

Iron Pathways and Iron Chelation Approaches in Viral, Microbial, and Fungal Infections

Iron is an essential element required to support the health of organisms. This element is critical for regulating the activities of cellular enzymes including those involved in cellular metabolism and DNA replication. Mechanisms that underlie the tight control of iron levels are crucial in mediating the interaction between microorganisms and their host and hence, the spread of infection. Microorganisms including viruses, bacteria, and fungi have differing iron acquisition/utilization mechanisms to support their ability to acquire/use iron (e.g., from free iron and heme). These pathways of iron uptake are associated with promoting their growth and virulence and consequently, their pathogenicity. Thus, controlling microorganismal survival by limiting iron availability may prove feasible through the use of agents targeting their iron uptake pathways and/or use of iron chelators as a means to hinder development of infections. This review will serve to assimilate findings regarding iron and the pathogenicity of specific microorganisms, and furthermore, find whether treating infections mediated by such organisms via iron chelation approaches may have potential clinical benefit.

Anemia, Iron Status, and HIV: A Systematic Review of the Evidence

People living with HIV (PLWHIV) are at high risk of anemia due to inadequate iron intake, HIV and opportunistic infections, and inflammation, and as a side effect of antiretroviral therapy. Though iron supplementation can reduce iron deficiency anemia (IDA) in the general population, its role in anemia and in the health of PLWHIV is unclear due to concerns that iron supplementation may increase HIV replication and risk of opportunistic infections. We systematically reviewed the evidence on indicators of iron status, iron intake, and clinical outcomes among adults and children with HIV. The evidence suggests that anemia is associated with an increased risk of all-cause mortality and incident tuberculosis among HIV-infected individuals, regardless of anemia type, and the magnitude of the risk is greater with more severe anemia. High serum ferritin is associated with adverse clinical outcomes, although it is unclear if this is due to high iron or inflammation from disease progression. One large observational study found an increased risk of all-cause mortality among HIV-infected adults if they received iron supplementation. Published randomized controlled trials of iron supplementation among PLWHIV tend to have small sample sizes and have been inconclusive in terms of effectiveness and safety. Large randomized trials exploring approaches to safely and effectively provide iron supplementation to PLWHIV are warranted.

Thiosemicarbazides: Updates on Antivirals Strategy

The challenges of viral infection have increased in recent decades due to the emergence of resistance, cross-resistance and drying up of antiviral drug discovery. Many neglected tropical viruses including the chikungunya virus, dengue virus & Japanese encephalitis virus have gradually become global pathogens. This has further increased the burden of viral infection which necessitates the continuous development of antiviral therapy. The antiviral chemistry began with the development of thiosemicarbazide derived thiosemicarbazones as antiviral. Although very few thiosemicarbazides have progressed into clinical application, it still inspires antiviral development. During last 3 decades (1990- 2020), several efforts have been made to develop suitable antiviral by using thiosemicarbazide scaffold. Its hybridization with other pharmacophores has been used as a strategy to enhance safety and efficacy. Cyclization and substitution of thiosemicarbazides have also been used to develop potent antiviral. With the ability to form coordinate bonds, thiosemicarbazides have been used either as metal complex or chelator against viruses. This work is an attempt to systematically review the research on the use of thiosemicarbazides as an antiviral scaffold. It also reviews the structure-activity relationship and translational suitability of thiosemicarbazide derived compounds.

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.

Impaired Hematological Status Increases the Risk of Mortality among HIV-Infected Adults Initiating Antiretroviral Therapy in Tanzania

BACKGROUND

Hematological status may predict HIV disease progression and mortality among adults initiating highly active antiretroviral therapy (HAART).

OBJECTIVES

We aimed to examine the relation of anemia and iron status at HAART initiation with survival and morbidity outcomes.

METHODS

We conducted a case-cohort study of 570 HIV-infected adults initiating HAART who were enrolled in a trial of multivitamins in Tanzania. Hemoglobin, serum ferritin, and hepcidin concentrations were assessed at HAART initiation and participants were followed up monthly. We adjusted serum ferritin for inflammation using a regression correction method to characterize hematological status. Cox proportional hazards models were used to estimate HRs for mortality and incident clinical outcomes.

RESULTS

We found an 83% prevalence of anemia, 15% prevalence of iron deficiency anemia, and 66% prevalence of anemia of chronic diseases (ACD). The prevalence of elevated iron was 33% and 19% had iron deficiency (ID). After multivariate adjustment, severe anemia (HR: 2.57; 95% CI: 1.49, 4.45) and ACD (HR: 4.71; 95% CI: 2.91, 7.62) were associated with increased risk of mortality as compared with nonanemic participants. In addition, both ID (HR: 2.65; 95% CI: 1.08, 7.78) and elevated iron (HR: 2.83; 95% CI: 2.10, 3.82) were associated with increased risk of mortality as compared with normal iron concentrations. Severe anemia and elevated iron concentrations were associated with incident wasting and >10% weight loss (P values <0.05).

CONCLUSIONS

Anemia and both ID and elevated iron were associated with increased mortality among HIV-infected adults initiating HAART. Safety and efficacy studies including anemia etiology, timing of HAART initiation, and dose of iron supplementation among HIV patients appear warranted.This trial was registered at clinicaltrials.gov as NCT00383669.

Alterations of redox and iron metabolism accompany the development of HIV latency

HIV-1 persists in a latent form during antiretroviral therapy, mainly in CD4+ T cells, thus hampering efforts for a cure. HIV-1 infection is accompanied by metabolic alterations, such as oxidative stress, but the effect of cellular antioxidant responses on viral replication and latency is unknown. Here, we show that cells survive retroviral replication, both in vitro and in vivo in SIVmac-infected macaques, by upregulating antioxidant pathways and the intertwined iron import pathway. These changes are associated with remodeling of promyelocytic leukemia protein nuclear bodies (PML NBs), an important constituent of nuclear architecture and a marker of HIV-1 latency. We found that PML NBs are hyper-SUMOylated and that PML protein is degraded via the ubiquitin-proteasome pathway in productively infected cells, before latency establishment and after reactivation. Conversely, normal numbers of PML NBs were restored upon transition to latency or by decreasing oxidative stress or iron content. Our results highlight antioxidant and iron import pathways as determinants of HIV-1 latency and support their pharmacologic inhibition as tools to regulate PML stability and impair latency establishment.

Iron intake is positively associated with viral load in antiretroviral naïve Brazilian men living with HIV

BACKGROUND

Iron homeostasis contribute for the human immunodeficiency virus (HIV) pathogenesis.

OBJECTIVES

We assessed the iron intake pattern in antiretroviral naïve Brazilian men living with HIV correlating with clinical and nutritional parameters.

METHODS

The iron consumption mean was estimated according to a food frequency questionnaire (FFQ), and a 3-day food record (3dFR) submitted to the patients. HIV viral load, CD4+ T cell counts, serum iron, haematological and anthropometrics parameters were recorded.

FINDINGS

Fifty-one HIV-infected adult men naïve for antiretroviral therapy (ART) were enrolled. The mean age of participants was 35 (SEM ± 1.28) years old, with mean time of HIV-1 infection of 1.78 (0-16.36, min-max) years. Majority (41.18%) had complete secondary, and 21.57% had tertiary educational level. The income was around 1x (54.90%) to 2x (41.18%) minimum wage. Fifty-four percent showed normal weight, while 40% were overweight. The patients showed normal mean values of haematological parameters, and mean serum iron was 14.40 µM (SEM ± 0.83). The FFQ showed moderate correlation with the 3dFR (ρ = 0.5436, p = 0.0009), and the mean values of iron intake were 10.55(± 0.92) mg/day, recorded by FFQ, and 15.75(± 1.51) mg/day, recorded by 3dFR. The iron intake, recorded by FFQ, negatively correlated with serum iron (ρ = -0.3448, p = 0.0132), and did not have influence in the CD4+ T cell counts [e.B 0.99 (0.97-1.01, 95% confidence interval (CI), p = 0.2]. However, the iron intake showed a positive effect in HIV viral load [e.B 1.12 (1.02-1.25, 95%CI), p < 0.01].

MAIN CONCLUSIONS

This study draws attention for the importance of iron intake nutritional counseling in people living with HIV. However, more studies are required to clarify the association between high iron intake and HIV infection and outcome.

Antimicrobial and Structural Properties of Metal Ions Complexes with Thiosemicarbazide Motif and Related Heterocyclic Compounds

Antibiotic resistance acquired by various bacterial fungal and viral pathogens poses therapeutic problems of increasing severity. Among the infections that are very difficult to treat, biofilm-associated cases are one of the most hazardous. Complex structure of a biofilm and unique physiology of the biofilm cells contribute to their extremely high resistance to environmental conditions, antimicrobial agents and the mechanisms of host immune response. Therefore, the biofilm formation, especially by multidrugresistant pathogens, is a serious medical problem, playing a pivotal role in the development of chronic and recurrent infections. These factors create a limitation for using traditional chemiotherapeutics and contribute to a request for development of new approaches for treatment of infectious diseases. Therefore, early reports on antimicrobial activity of several complexes of metal ions, bearing thiosemicarbazide or thiosemicarbazones as the ligands, gave a boost to worldwide search for new, more efficient compounds of this class, to be used as alternatives to commonly known drugs. In general, depending on the presence of other heteroatoms, these ligands may function in a di-, tri- or tetradentate forms (e.g., of N,S,-, N,N,S-, N,N,N,S-, N,N,S,S-, or N,S,O-type), which impose different coordination geometries to the resultant complexes. In the first part of this review, we describe the ways of synthesis and the structures of the ligands based on the thiosemicarbazone motif, while the second part deals with the antimicrobial activity of their complexes with selected metal ions.

Essential trace elements and progression and management of HIV infection

This review was written to update the review that we published in Nutrition Research in 2007 by examining studies published in the last 11 years which describe the effects of trace mineral deficiencies and micronutrient supplementation on HIV infection and its progression. In addition, we included studies that explore the interactions between Highly Active Anti-Retroviral Therapy (HAART) and micronutrient nutrition, focusing on the essential trace minerals. This review summarizes the results described in relevant articles that were identified by literature searches conducted using the OVID Medline database. Four of the nine essential trace minerals, specifically chromium, iron, selenium, and zinc, can influence HIV progression and/or its treatment. Notably, copper-containing filters may prevent transmission of the HIV virus via breastfeeding. However, there is a lack of good evidence to date that fluoride, iodine, manganese, or molybdenum influence HIV infection. Recent studies reveal that HAART can alter serum trace mineral and vitamin concentrations, but the effects vary based on the medications used. Although they have contributed useful new data, the sample sizes for most of these studies were too small to draw definitive conclusions for introducing changes in the management of HIV infection. Larger studies are needed to better understand and define the roles of trace mineral and vitamin deficiencies and micronutrient supplementation in the management and treatment of HIV-infected patients.

Protein Phosphatase-1 -targeted Small Molecules, Iron Chelators and Curcumin Analogs as HIV-1 Antivirals

BACKGROUND

Despite efficient suppression of HIV-1 replication, current antiviral drugs are not able to eradicate HIV-1 infection. Permanent HIV-1 suppression or complete eradication requires novel biological approaches and therapeutic strategies. Our previous studies showed that HIV-1 transcription is regulated by host cell protein phosphatase-1. We also showed that HIV-1 transcription is sensitive to the reduction of intracellular iron that affects cell cycle-dependent kinase 2. We developed protein phosphatase 1-targeting small molecules that inhibited HIV-1 transcription. We also found an additional class of protein phosphatase-1-targeting molecules that activated HIV-1 transcription and reported HIV-1 inhibitory iron chelators and novel curcumin analogs that inhibit HIV-1. Here, we review HIV-1 transcription and replication with focus on its regulation by protein phosphatase 1 and cell cycle dependent kinase 2 and describe novel small molecules that can serve as future leads for anti-HIV drug development.

RESULTS

Our review describes in a non-exhaustive manner studies in which HIV-1 transcription and replication are targeted with small molecules. Previously, published studies show that HIV-1 can be inhibited with protein phosphatase-1-targeting and iron chelating compounds and curcumin analogs. These results are significant in light of the current efforts to eradicate HIV-1 through permanent inhibition. Also, HIV-1 activating compounds can be useful for "kick and kill" therapy in which the virus is reactivated prior to its inhibition by the combination antiretroviral therapy.

CONCLUSION

The studies described in our review point to protein phosphatase-1 as a new drug target, intracellular iron as subject for iron chelation and novel curcumin analogs that can be developed for novel HIV-1 transcription- targeting therapeutics.

Impaired Hematologic Status in Relation to Clinical Outcomes among HIV-Infected Adults from Uganda: A Prospective Cohort Study

Impaired hematologic status (IHS) was investigated as a determinant of immune function defined as cluster of differentiation 4 (CD4) T-helper cell count, quality of life (QOL) weight and hospitalization/mortality over 18-months among 398 adult persons living with HIV/AIDS (PLWHA) on anti-retroviral therapy. IHS was defined as having anemia at baseline (Hemoglobin: <12 g/dL for women and <13 g/dL for men), time-updated anemia or having low (<30 μg/L) or high (>200 μg/L for men and >150 μg/L for women) ferritin levels at baseline. Months-to-hospitalization/death or study-end (if no event) was calculated from enrollment. Multivariable linear-mixed models quantified associations between IHS and changes in CD4 cell-count, weight gain and QOL. Cox proportional hazards models calculated hazard ratios (HR) and corresponding 95% confidence intervals (CI) for IHS-related differences in time-to-hospitalization/death. The prevalences of anemia and high and low ferritin levels at baseline were 48.7% (n = 194), 40.5% (n = 161) and 17% (n = 68), respectively. Most patients (63.4%, n = 123) remained anemic during follow-up. Weight gained (ferritin-time interaction, p < 0.01) and QOL (anemia-time interaction, p = 0.05; ferritin-time interaction, p = 0.01) were lower for PLWHA with versus without IHS. Relative to anemia-free/normal ferritin, the risk of hospitalization/death was elevated for PLWHA with anemia (HR = 2.0; 95% CI: 1.2-3.6), low or high ferritin (HR: 1.8-1.9, 95% CI: 0.9-4.1) and those that developed new/persistent/progressive anemia (HR: 2.3-6.7, 95% CI: 1.0-12.7). Among PLWHA, IHS predicted deficits in QOL, low weight gain and a high risk of hospitalization/death. Intervention to mitigate persistent IHS may be warranted among PLWHA on long-term highly active antiretroviral therapy (HAART) to improve health outcomes.

Iron overload down-regulates the expression of the HIV-1 Rev cofactor eIF5A in infected T lymphocytes

BACKGROUND

Changes in iron metabolism frequently accompany HIV-1 infection. However, while many clinical and in vitro studies report iron overload exacerbates the development of infection, many others have found no correlation. Therefore, the multi-faceted role of iron in HIV-1 infection remains enigmatic.

METHODS

RT-qPCR targeting the LTR region, gag, Tat and Rev were performed to measure the levels of viral RNAs in response to iron overload. Spike-in SILAC proteomics comparing i) iron-treated, ii) HIV-1-infected and iii) HIV-1-infected/iron treated T lymphocytes was performed to define modifications in the host cell proteome. Data from quantitative proteomics were integrated with the HIV-1 Human Interaction Database for assessing any viral cofactors modulated by iron overload in infected T lymphocytes.

RESULTS

Here, we demonstrate that the iron overload down-regulates HIV-1 gene expression by decreasing the levels of viral RNAs. In addition, we found that iron overload modulates the expression of many viral cofactors. Among them, the downregulation of the REV cofactor eIF5A may correlate with the iron-induced inhibition of HIV-1 gene expression. Therefore, we demonstrated that eiF5A downregulation by shRNA resulted in a significant decrease of Nef levels, thus hampering HIV-1 replication.

CONCLUSIONS

Our study indicates that HIV-1 cofactors influenced by iron metabolism represent potential targets for antiretroviral therapy and suggests eIF5A as a selective target for drug development.

Virus-host interactions under hypoxia

Oxygen tension can exert a significant effect on viral propagation in vitro and possibly in vivo. In general, hypoxia restricts the replication of viruses that naturally infect tissues exposed to ambient oxygen and induces the growth of viruses that naturally target tissues exposed to low oxygen. Some viruses can reprogram cell bioenergetics towards lowering cellular respiration and therefore oxygen consumption in order to support their replication. Aim of this review is to summarize findings on the interplay between viral infection and oxygen levels, highlighting the implicated oxygen tension-sensitive elements and metabolic determinants and concluding with possible therapeutic approaches targeting these mediators.

Relationship Between Blood Concentrations of Hepcidin and Anemia Severity, Mycobacterial Burden, and Mortality Among Patients With HIV-Associated Tuberculosis

Background

Anemia is very common in patients with human immunodeficiency virus (HIV)–associated tuberculosis, and hepcidin may be key in mediating this. We explored the relationship between blood hepcidin concentrations and anemia severity, mycobacterial burden and mortality in patients with HIV-associated tuberculosis.

Methods

Consecutive unselected HIV-infected adults in South Africa were systematically investigated for tuberculosis. Three groups were studied: 116 hospitalized inpatients with HIV infection and tuberculosis (hereafter, “hospitalized patients”), 58 ambulatory outpatients with HIV infection and newly diagnosed tuberculosis (hereafter, “ambulatory patients with tuberculosis”), and 58 ambulatory outpatients with HIV infection and without tuberculosis (hereafter, “ambulatory patients without tuberculosis”). Blood hepcidin concentrations were determined for all patients. Vital status at 3 months was determined, and independent predictors of mortality were identified.

Results

Median hepcidin concentrations were 38.8 ng/mL among hospitalized patients, 19.1 ng/mL among ambulatory patients with tuberculosis, and 5.9 ng/mL among ambulatory patients without tuberculosis (P < .001). In both groups with HIV-associated tuberculosis, hepcidin concentrations were strongly associated with greater anemia severity. Additionally, strong, graded associations were observed between hepcidin and composite indices of mycobacterial burden and dissemination. Patients dying within 3 months had significantly higher hepcidin concentrations, which independently predicted mortality.

Conclusions

High hepcidin concentrations were strongly associated with disseminated disease, anemia, and poor prognosis in patients with HIV-associated tuberculosis. Hepcidin may be a mechanistically important mediator underlying the high prevalence of severe anemia in these patients.

Ferritin protect shrimp Litopenaeus vannamei from WSSV infection by inhibiting virus replication

Iron is considered as an essential element for all living organisms. Therefore, limiting iron availability may be key part of the host's innate immune response to various pathogens. Ferritin is a major iron storage protein in living cells and plays an important role in iron homeostasis. One way the host can transiently reduce iron bioavailability is by ferritin over expression. In invertebrates, ferritin was found to be up-regulated after pathogens challenge and is considered to be an important element in the innate immune system. This study was designed to investigate the involvement of ferritin in shrimp Litopenaeus vannamei defense against WSSV. We discovered that the viral load of shrimp injected with recombinant ferritin protein was lower than that of control group. The suppression of ferritin by dsRNA increased susceptibility to WSSV with 3-fold high viral copies. The present study documented that ferritin protected shrimp L. vannamei from WSSV by inhibiting virus replication. We presume that ferritin reduce iron availability, leading to inhibit the activity of ribonucleotide reductase and delay the replication of virus genome. This study provided new insights into the understanding of molecular responses and defense mechanisms in shrimp against WSSV.

Serum hepcidin levels in women infected with HIV-1 under antiviral therapy

Accumulating data suggest that iron may have a role in the regulation of HIV-infection. In the present study, we determined by radioimmunoassay the levels of hepcidin, a key regulator of iron homeostasis, in sera of 182 women infected with HIV-1 under highly active antiretroviral therapy (HAART). In the total cohort, hepcidin levels were lower in individuals infected with HIV than in controls (3.20 ± 3.06 vs. 5.68 ± 3.66 nmol/L, P = 0.009). Serum hepcidin concentrations were strongly correlated positively with iron, ferritin, urea, and uric acid. In the total cohort of patients with abnormal viral load and CD4 cell count <500 cells/mm(3) , a strong positive correlation was found between hepcidin and viral load. Hepcidin level was significantly higher in HIV-patients with high viremia than in patients with undetectable viral load. Iron level was significantly lower in HIV-patients with high viral load compared with patients with undetectable viral load. This study suggests that hepcidin controls serum iron, especially in response of iron utilization by HIV for viral replication. The possibility of using inhibitors of hepcidin expression as adjunct therapy for HIV-patients is discussed.

Serum ferritin in HIV-positive patients is related to immune deficiency and inflammatory activity

To analyse the prevalence of high ferritin levels in asymptomatic HIV patients and its related factors we conducted a cross-sectional study of a cohort of HIV outpatients in regular follow-up. Epidemiological, clinical, analytical and therapeutic data were collected. Patients completed a questionnaire about cardiovascular risk factors and underwent a physical examination and a 12-h fasting blood analysis. High ferritin levels were defined as a plasma ferritin level >200 µg/L in women and >300 µg/L in men. A total of 571 patients (78.1% men) were included. Median age was 43.2 years, HIV sexual transmission 68.5%, median CD4 count 474 cells/µL, 36.3% AIDS cases, 86.2% on antiretroviral therapy and 74.8% of them with undetectable viral load; 14.6% metabolic syndrome criteria, and mean cardiovascular risk at 10 years 6.67%. High ferritin levels prevalence was 11%, and related factors were a CD4 count <350 cells/µL (odds ratio, OR 2.37 [1.3-4.1], p = 0.003), ultrasensitive C-reactive protein >3 mg/L (OR 2.67 [1.5-4.7], p = 0.001) and chronic hepatitis C virus infection (OR 2.77 [1.5-4.9], p = 0.001). High ferritin levels are not uncommon in HIV patients, and they correlate with immunosuppression defined as CD4 count <350 cells/µL, higher ultrasensitive C-reactive protein and hepatitis C virus infection, and in contrast to the general population, they are not related to increased cardiovascular risk or metabolic syndrome.

Drug-induced reactivation of apoptosis abrogates HIV-1 infection

HIV-1 blocks apoptosis, programmed cell death, an innate defense of cells against viral invasion. However, apoptosis can be selectively reactivated in HIV-infected cells by chemical agents that interfere with HIV-1 gene expression. We studied two globally used medicines, the topical antifungal ciclopirox and the iron chelator deferiprone, for their effect on apoptosis in HIV-infected H9 cells and in peripheral blood mononuclear cells infected with clinical HIV-1 isolates. Both medicines activated apoptosis preferentially in HIV-infected cells, suggesting that the drugs mediate escape from the viral suppression of defensive apoptosis. In infected H9 cells, ciclopirox and deferiprone enhanced mitochondrial membrane depolarization, initiating the intrinsic pathway of apoptosis to execution, as evidenced by caspase-3 activation, poly(ADP-ribose) polymerase proteolysis, DNA degradation, and apoptotic cell morphology. In isolate-infected peripheral blood mononuclear cells, ciclopirox collapsed HIV-1 production to the limit of viral protein and RNA detection. Despite prolonged monotherapy, ciclopirox did not elicit breakthrough. No viral re-emergence was observed even 12 weeks after drug cessation, suggesting elimination of the proviral reservoir. Tests in mice predictive for cytotoxicity to human epithelia did not detect tissue damage or activation of apoptosis at a ciclopirox concentration that exceeded by orders of magnitude the concentration causing death of infected cells. We infer that ciclopirox and deferiprone act via therapeutic reclamation of apoptotic proficiency (TRAP) in HIV-infected cells and trigger their preferential elimination. Perturbations in viral protein expression suggest that the antiretroviral activity of both drugs stems from their ability to inhibit hydroxylation of cellular proteins essential for apoptosis and for viral infection, exemplified by eIF5A. Our findings identify ciclopirox and deferiprone as prototypes of selectively cytocidal antivirals that eliminate viral infection by destroying infected cells. A drug-based drug discovery program, based on these compounds, is warranted to determine the potential of such agents in clinical trials of HIV-infected patients.

Role of cellular iron and oxygen in the regulation of HIV-1 infection

Despite efficient antiretroviral therapy, eradication of HIV-1 infection is challenging and requires novel biological insights and therapeutic strategies. Among other physiological and environmental factors, intracellular iron greatly affects HIV-1 replication. Higher iron stores were shown to be associated with faster progression of HIV-1 infection and to inversely correlate with the survival of HIV-1 infected patients. Iron is required for several steps in the HIV-1 life cycle, including reverse transcription, HIV-1 gene expression and capsid assembly. Here, the authors present a comprehensive review of the molecular mechanisms involved in iron- and oxygen-mediated regulation of HIV-1 replication. We also propose key intracellular pathways that may be involved in regulating HIV-1 replication, via protein kinase complexes, CDK9/cyclin T1 and CDK 2/cyclin E, protein phosphatase-1 and other host factors.

Iron status in HIV-1 infection: implications in disease pathology

BACKGROUND

There had been conflicting reports with levels of markers of iron metabolism in HIV infection. This study was therefore aimed at investigating iron status and its possible mediation of severity of HIV- 1 infection and pathogenesis.

METHOD

Eighty (80) anti-retroviral naive HIV-1 positive and 50 sero-negative controls were recruited for the study. Concentrations of serum total iron, transferrin, total iron binding capacity (TIBC), CD4+ T -lymphocytes, vitamin C, zinc, selenium and transferrin saturation were estimated.

RESULTS

The mean CD4+ T-lymphocyte cell counts, serum iron, TIBC, transferrin saturation for the tests and controls were 319 ± 22, 952 ± 57 cells/μl (P < 0.001), 35 ± 0.8, 11.8 ± 0.9 μmol/l (P < 0.001), 58.5 ± 2.2, 45.2 ± 2.4 μmol/l (P < 0.005) and 68.8 ± 3.3, 27.7 ± 2.2%, (P <0.001), respectively, while mean concentrations of vitamin C, zinc and selenium were 0.03 ± 0.01, 0.3 ± 0.04 (P < 0.001), 0.6 ± 0.05, 11.9 ± 0.26 μmol/l (P < 0.001) and 0.1 ± 0.01, 1.2 ± 0.12 μmol/l (P < 0.001) respectively. Furthermore, CD4+ T-lymphocyte cell count had a positive correlation with levels of vitamin C (r = 0.497, P < 0.001), zinc (r = 0.737, P < 0.001), selenium (r = 0.639, P < 0.001) and a negative correlation with serum iron levels (r = -0.572, P < 0.001).

CONCLUSION

It could be inferred that derangement in iron metabolism, in addition to oxidative stress, might have contributed to the depletion of CD4+ T cell population in our subjects and this may result in poor prognosis of the disease.

In vitro anti-HIV-1 activity of salicylidene acylhydrazide compounds

Salicylidene acylhydrazide compounds have been shown to inhibit bacterial pathogens, including Chlamydia and Neisseria gonorrhoeae. If such compounds could also target HIV-1, their potential use as topical microbicides to prevent sexually transmitted infections would be considerable. In this study, the in vitro anti-HIV-1 activity, cytotoxicity and mechanism of action of several salicylidene acylhydrazides were determined. Inhibitory activity was assessed using TZM-bl cells and primary peripheral blood mononuclear cells (PBMCs) as targets for HIV-1 infection. Antiviral activity was measured against cell-free and cell-associated virus and in vaginal fluid and semen simulants. Since the antibacterial activity of salicylidene acylhydrazides is reversible by Fe(2+), the ability of Fe(2+) and other cations to reverse the anti-HIV-1 activity of the compounds was determined. Real-time PCR was also employed to determine the stage affected in the HIV-1 replication cycle. Four compounds with 50% inhibitory concentrations against HIV-1 of 1-7 μM were identified. In vitro toxicity varied but was generally limited. Activity was similar against three R5 clade B primary isolates and whether the target for virus replication was TZM-bl cells or PBMCs. Compounds inhibited cell-free and cell-associated virus and were active in vaginal fluid and semen simulants. Fe(2+), but not other cations, reversed the anti-HIV-1 effect. Finally, the inhibitory effect of the compounds occurred at a post-integration step. In conclusion, salicylidene acylhydrazides were identified with in vitro anti-HIV-1 activity in the micromolar range. The activity of these compounds against other sexually transmitted pathogens makes them potential candidates to formulate for use as a broad-spectrum topical genital microbicide.

Advances in iron chelation: an update

INTRODUCTION

Oxidative stress (caused by excess iron) can result in tissue damage, organ failure and finally death, unless treated by iron chelators. The causative factor in the etiology of a variety of disease states is the presence of iron-generated reactive oxygen species (ROS), which can result in cell damage or which can affect the signaling pathways involved in cell necrosis-apoptosis or organ fibrosis, cancer, neurodegeneration and cardiovascular, hepatic or renal dysfunctions. Iron chelators can reduce oxidative stress by the removal of iron from target tissues. Equally as important, removal of iron from the active site of enzymes that play key roles in various diseases can be of considerable benefit to the patients.

AREAS COVERED

This review focuses on iron chelators used as therapeutic agents. The importance of iron in oxidative damage is discussed, along with the three clinically approved iron chelators.

EXPERT OPINION

A number of iron chelators are used as approved therapeutic agents in the treatment of thalassemia major, asthma, fungal infections and cancer. However, as our knowledge about the biochemistry of iron and its role in etiologies of seemingly unrelated diseases increases, new applications of the approved iron chelators, as well as the development of new iron chelators, present challenging opportunities in the areas of drug discovery and development.

Hepcidin induces HIV-1 transcription inhibited by ferroportin

BACKGROUND

Physiological regulation of cellular iron involves iron export by the membrane protein, ferroportin, the expression of which is induced by iron and negatively modulated by hepcidin. We previously showed that iron chelation is associated with decreased HIV-1 transcription. We hypothesized that increased iron export by ferroportin might be associated with decreased HIV-1 transcription, and degradation of ferroportin by hepcidin might in turn induce HIV-1 transcription and replication. Here, we analyzed the effect of ferroportin and hepcidin on HIV-1 transcription.

RESULTS

Expression of ferroportin was associated with reduced HIV-1 transcription in 293T cells and addition of hepcidin to ferroportin-expressing cells counteracted this effect. Furthermore, exposure of promonocytic THP-1 cells to hepcidin was associated with decreased ferroportin expression, increased intracellular iron and induction of reporter luciferase gene expression. Finally, exposure of human primary macrophages and CD4+ T cells to hepcidin and iron was also associated with induction of viral production.

CONCLUSION

Our results suggest that the interplay between ferroportin-mediated iron export and hepcidin-mediated degradation of ferroportin might play a role in the regulation of HIV-1 transcription and may be important for understanding of HIV-1 pathogenesis.

Towards a unifying, systems biology understanding of large-scale cellular death and destruction caused by poorly liganded iron: Parkinson's, Huntington's, Alzheimer's, prions, bactericides, chemical toxicology and others as examples

Exposure to a variety of toxins and/or infectious agents leads to disease, degeneration and death, often characterised by circumstances in which cells or tissues do not merely die and cease to function but may be more or less entirely obliterated. It is then legitimate to ask the question as to whether, despite the many kinds of agent involved, there may be at least some unifying mechanisms of such cell death and destruction. I summarise the evidence that in a great many cases, one underlying mechanism, providing major stresses of this type, entails continuing and autocatalytic production (based on positive feedback mechanisms) of hydroxyl radicals via Fenton chemistry involving poorly liganded iron, leading to cell death via apoptosis (probably including via pathways induced by changes in the NF-κB system). While every pathway is in some sense connected to every other one, I highlight the literature evidence suggesting that the degenerative effects of many diseases and toxicological insults converge on iron dysregulation. This highlights specifically the role of iron metabolism, and the detailed speciation of iron, in chemical and other toxicology, and has significant implications for the use of iron chelating substances (probably in partnership with appropriate anti-oxidants) as nutritional or therapeutic agents in inhibiting both the progression of these mainly degenerative diseases and the sequelae of both chronic and acute toxin exposure. The complexity of biochemical networks, especially those involving autocatalytic behaviour and positive feedbacks, means that multiple interventions (e.g. of iron chelators plus antioxidants) are likely to prove most effective. A variety of systems biology approaches, that I summarise, can predict both the mechanisms involved in these cell death pathways and the optimal sites of action for nutritional or pharmacological interventions.

Iron chelators of the di-2-pyridylketone thiosemicarbazone and 2-benzoylpyridine thiosemicarbazone series inhibit HIV-1 transcription: identification of novel cellular targets--iron, cyclin-dependent kinase (CDK) 2, and CDK9

HIV-1 transcription is activated by HIV-1 Tat protein, which recruits cyclin-dependent kinase 9 (CDK9)/cyclin T1 and other host transcriptional coactivators to the HIV-1 promoter. Tat itself is phosphorylated by CDK2, and inhibition of CDK2 by small interfering RNA, the iron chelator 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone (311), and the iron chelator deferasirox (ICL670) inhibits HIV-1 transcription. Here we have analyzed a group of novel di-2-pyridylketone thiosemicarbazone- and 2-benzoylpyridine thiosemicarbazone-based iron chelators that exhibit marked anticancer activity in vitro and in vivo (Proc Natl Acad Sci USA 103:7670-7675, 2006; J Med Chem 50:3716-3729, 2007). Several of these iron chelators, in particular 2-benzoylpyridine 4-allyl-3-thiosemicarbazone (Bp4aT) and 2-benzoylpyridine 4-ethyl-3-thiosemicarbazone (Bp4eT), inhibited HIV-1 transcription and replication at much lower concentrations than did 311 and ICL670. Neither Bp4aT nor Bp4eT were toxic after a 24-h incubation. However, longer incubations for 48 h or 72 h resulted in cytotoxicity. Analysis of the molecular mechanism of HIV-1 inhibition showed that the novel iron chelators inhibited basal HIV-1 transcription, but not the nuclear factor-κB-dependent transcription or transcription from an HIV-1 promoter with inactivated SP1 sites. The chelators inhibited the activities of CDK2 and CDK9/cyclin T1, suggesting that inhibition of CDK9 may contribute to the inhibition of HIV-1 transcription. Our study suggests the potential usefulness of Bp4aT or Bp4eT in antiretroviral regimens, particularly where resistance to standard treatment occurs.

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.

Iron availability and infection

BACKGROUND

To successfully sustain an infection, nearly all bacteria, fungi and protozoa require a continuous supply of host iron.

METHODS

Literature review.

RESULTS

Mechanisms of microbial iron acquisition are determinants for the kinds of cells, tissues and hosts in which pathogens can flourish. As a corollary, hosts possess an array of iron withholding devices whereby they can suppress or abort microbial invasions.

GENERAL SIGNIFICANCE

Awareness of environmental and behavioral methods that can prevent iron loading plus development of pharmaceutical agents that can block microbial access to iron may help to reduce our dependence on antibiotics.

Elevated iron status strongly predicts mortality in West African adults with HIV infection

OBJECTIVE

To comprehensively assess iron status and determine whether elevated iron status, like anemia, predicts mortality.

METHODS

We followed 1362 Gambian adults (53% female) in an HIV-seroprevalent clinic-based cohort over 11.5 years to ascertain all-cause mortality. Baseline iron status (iron, soluble transferrin receptor [sTfR], transferrin, ferritin, transferrin saturation, log [transferrin receptor: ferritin]), age, gender, ethnicity, hemoglobin, body mass index, HIV type, absolute CD4 count, malaria status, and [alpha]-(1)-antichymotrypsin were measured.

RESULTS

The mortality rate was 25.9/100 person-years. Elevated iron universally predicted greater mortality compared to normal iron status for all iron status indices, with the exception of sTfR in unadjusted models. In fully adjusted models, transferrin (elevated vs. normal, hazard ratio [HR]: 1.77; 95% confidence interval [CI]: 1.30 to 2.42; P < 0.001), ferritin (elevated vs. normal, HR: 1.40; 95% CI: 1.07 to 1.83; P = 0.014), and the combined iron status index (highly elevated vs. normal, HR: 2.20; 95% CI: 1.16 to 4.18; P = 0.016) remained significant predictors. As expected, hemoglobin (Hb) concentration and absolute CD4 counts were each inversely associated with mortality.

CONCLUSIONS

Elevated iron status predicts mortality in HIV infection, even after adjustment for immunosuppression and other confounders. This finding has implications in the clinical monitoring of disease progression and for iron-supplementation practices in areas of high HIV prevalence.

Ferritin levels during structured treatment interruption of highly active antiretroviral therapy

OBJECTIVE

The aim of the study was to investigate the influence of highly active antiretroviral therapy (HAART) on iron status and, conversely, the influence of iron status on the response to HAART.

METHODS

Ferritin levels were retrospectively determined in stored plasma from 138 HAART-naïve, moderately immunosuppressed HIV-infected Thai patients participating in a structured treatment interruption trial. Ferritin levels were determined at three predefined time-points: (1) HAART initiation; (2) HAART discontinuation; and (3) HAART resumption.

RESULTS

At baseline, 31% and 16% of the HIV-infected patients included in the study had high (>200 ng/mL) and low (<30 ng/mL) ferritin levels, respectively. Ninety-five per cent of patients with low ferritin levels were female. Ferritin decreased significantly during the interruption phase of HAART (-8.8 ng/mL; P=0.0005) but remained elevated in 62% of the patients with high baseline levels. A low baseline ferritin level was associated with a shorter time (P=0.041) to reach the CD4 cell target for HAART interruption (350 cells/microL), compared with a normal or high baseline ferritin level. Moreover, in a multivariate model, the relative risk (RR) of arriving at this CD4 cell target was significantly higher [RR 1.81; 95% confidence interval (CI) 1.05-3.14] in patients with low baseline ferritin. It is unlikely that inflammation affected ferritin in our patients, as mean levels of C-reactive protein were not elevated in patients with either high or low ferritin levels.

CONCLUSIONS

Both high and low ferritin levels were highly prevalent in moderately immunosuppressed HIV-positive Thai patients. Structured treatment interruption of HAART resulted in a significant decrease in overall ferritin levels. Furthermore, subjects with low baseline ferritin levels had a faster and greater CD4 response to HAART, suggesting a potential beneficial effect of iron deficiency on immunological recovery after initiation of HAART.

Iron chelators ICL670 and 311 inhibit HIV-1 transcription

HIV-1 replication is induced by an excess of iron and iron chelation by desferrioxamine (DFO) inhibits viral replication by reducing proliferation of infected cells. Treatment of cells with DFO and 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone (311) inhibit expression of proteins that regulate cell-cycle progression, including cycle-dependent kinase 2 (CDK2). Our recent studies showed that CDK2 participates in HIV-1 transcription and viral replication suggesting that inhibition of CDK2 by iron chelators might also affect HIV-1 transcription. Here we evaluated the effect of a clinically approved orally effective iron chelator, 4-[3,5-bis-(hydroxyphenyl)-1,2,4-triazol-1-yl]-benzoic acid (ICL670) and 311 on HIV-1 transcription. Both ICL670 and 311 inhibited Tat-induced HIV-1 transcription in CEM-T cells, 293T and HeLa cells. Neither ICL670 nor 311 induced cytotoxicity at concentrations that inhibited HIV-1 transcription. The chelators decreased cellular activity of CDK2 and reduced HIV-1 Tat phosphorylation by CDK2. Neither ICL670A or 311 decreased CDK9 protein level but significantly reduced association of CDK9 with cyclin T1 and reduced phosphorylation of Ser-2 residues of RNA polymerase II C-terminal domain. In conclusion, our findings add to the evidence that iron chelators can inhibit HIV-1 transcription by deregulating CDK2 and CDK9. Further consideration should be given to the development of iron chelators for future anti-retroviral therapeutics.

Association of hemochromatosis with infectious diseases: expanding spectrum

Withholding iron from potential pathogens is a host defense strategy. There is evidence that iron overload per se compromises the ability of phagocytes to kill microorganisms. Several hypotheses exist to explain the association of hemochromatosis with infection. A combination of mechanisms likely contributes to the increase in susceptibility to infection in these patients. A review of the current literature delineating various pathogens to which patients with hemochromatosis are potentially susceptible, and recent advances in the understanding of the association of hemochromatosis with infection, are discussed.

Host-pathogen interactions: the role of iron

Iron is essential for both host and pathogen, and complex systems of acquisition and utilization have evolved in competition. Our increasing knowledge of the basic mechanisms of homeostasis and their adaptation during deficiency, overload, and infection indicate that iron is a key regulator of host pathogen interactions. This review concentrated on the clinical and public health aspects of the interaction between the iron acquisition mechanisms of select pathogens of public health importance with host iron homeostasis. Knowledge of these interactions is essential in assessing likely morbidity responses to supplementation.

Necrosis of host cells and survival of pathogens following iron overload in an in vitro model of co-infection with human immunodeficiency virus (HIV) and Mycobacterium tuberculosis

Mycobacterium tuberculosis, human immunodeficiency virus (HIV) and iron overload (dietary/hereditary) are very common in sub-Saharan Africa. The requirement for iron as a crucial factor for cellular processes is well established, as are the disadvantages of excess iron in the system. Mycobacterium tuberculosis and HIV are believed to have a reciprocal effect on each another. An in vitro model was evaluated where chronically HIV-infected cells were secondarily exposed to M. tuberculosis in the presence of iron overload. Co-infection alone caused cell type-specific reductions in host cell viability, more than doubled the number of viral particles and stimulated bacterial viability. Excess iron (in addition to co-infection) further decreased cell viability, with a marked increase in necrosis (rather than apoptosis) of cells, and was also found to enhance both HIV (26%; P<0.01) and M. tuberculosis (47%; P<0.01) replication. Chelation of excess iron with deferoxamine abrogated the enhanced replication of the pathogens, with a marginal restoration in host cell viability. These findings demonstrate that (i) increased levels of iron in HIV-infected patients secondarily co-infected with M. tuberculosis elevate viral replication, which could lead to rapid disease progression, and (ii) iron chelation may serve as a means to slow/decelerate these processes.

Haptoglobin polymorphism in a HIV-1 seropositive Brazilian population

BACKGROUND

Haptoglobin (Hp) is a plasma protein with antioxidant and immunomodulatory properties. Three main genotypes/phenotypes (Hp1-1, Hp2-1, Hp2-2) show distinctive efficiencies in their activities and have been related to susceptibility and outcome in different diseases, including HIV infection.

OBJECTIVE

To compare Hp genotype distribution between HIV-1 seropositive patients and healthy controls.

METHODS

387 Brazilian HIV-1 seropositive patients, subclassified as A, B, and C according to the Centers for Disease Control, were compared with 142 healthy controls. The influence of the polymorphism on iron status (serum iron, ferritin, transferrin, transferrin saturation), acute phase proteins (Hp, C reactive protein, fibrinogen, albumin), the HIV-1 viral load, and CD4+ T lymphocyte counts was examined.

RESULTS

Apart from finding lower Hp concentrations among individuals with genotype Hp2-2, no other significant difference was observed.

CONCLUSIONS

No association was found between Hp genotype and either HIV status or indices of HIV progression.