Iron and the Risk of Infection

In defence of ferroptosis

Rampant phospholipid peroxidation initiated by iron causes ferroptosis unless this is restrained by cellular defences. Ferroptosis is increasingly implicated in a host of diseases, and unlike other cell death programs the physiological initiation of ferroptosis is conceived to occur not by an endogenous executioner, but by the withdrawal of cellular guardians that otherwise constantly oppose ferroptosis induction. Here, we profile key ferroptotic defence strategies including iron regulation, phospholipid modulation and enzymes and metabolite systems: glutathione reductase (GR), Ferroptosis suppressor protein 1 (FSP1), NAD(P)H Quinone Dehydrogenase 1 (NQO1), Dihydrofolate reductase (DHFR), retinal reductases and retinal dehydrogenases (RDH) and thioredoxin reductases (TR). A common thread uniting all key enzymes and metabolites that combat lipid peroxidation during ferroptosis is a dependence on a key cellular reductant, nicotinamide adenine dinucleotide phosphate (NADPH). We will outline how cells control central carbon metabolism to produce NADPH and necessary precursors to defend against ferroptosis. Subsequently we will discuss evidence for ferroptosis and NADPH dysregulation in different disease contexts including glucose-6-phosphate dehydrogenase deficiency, cancer and neurodegeneration. Finally, we discuss several anti-ferroptosis therapeutic strategies spanning the use of radical trapping agents, iron modulation and glutathione dependent redox support and highlight the current landscape of clinical trials focusing on ferroptosis.

Restoring the infected powerhouse: Mitochondrial quality control in sepsis

Sepsis is a dysregulated host response to an infection, characterized by organ failure. The pathophysiology is complex and incompletely understood, but mitochondria appear to play a key role in the cascade of events that culminate in multiple organ failure and potentially death. In shaping immune responses, mitochondria fulfil dual roles: they not only supply energy and metabolic intermediates crucial for immune cell activation and function but also influence inflammatory and cell death pathways. Importantly, mitochondrial dysfunction has a dual impact, compromising both immune system efficiency and the metabolic stability of end organs. Dysfunctional mitochondria contribute to the development of a hyperinflammatory state and loss of cellular homeostasis, resulting in poor clinical outcomes. Already in early sepsis, signs of mitochondrial dysfunction are apparent and consequently, strategies to optimize mitochondrial function in sepsis should not only prevent the occurrence of mitochondrial dysfunction, but also cover the repair of the sustained mitochondrial damage. Here, we discuss mitochondrial quality control (mtQC) in the pathogenesis of sepsis and exemplify how mtQC could serve as therapeutic target to overcome mitochondrial dysfunction. Hence, replacing or repairing dysfunctional mitochondria may contribute to the recovery of organ function in sepsis. Mitochondrial biogenesis is a process that results in the formation of new mitochondria and is critical for maintaining a pool of healthy mitochondria. However, exacerbated biogenesis during early sepsis can result in accumulation of structurally aberrant mitochondria that fail to restore bioenergetics, produce excess reactive oxygen species (ROS) and exacerbate the disease course. Conversely, enhancing mitophagy can protect against organ damage by limiting the release of mitochondrial-derived damage-associated molecules (DAMPs). Furthermore, promoting mitophagy may facilitate the growth of healthy mitochondria by blocking the replication of damaged mitochondria and allow for post sepsis organ recovery through enabling mitophagy-coupled biogenesis. The remaining healthy mitochondria may provide an undamaged scaffold to reproduce functional mitochondria. However, the kinetics of mtQC in sepsis, specifically mitophagy, and the optimal timing for intervention remain poorly understood. This review emphasizes the importance of integrating mitophagy induction with mtQC mechanisms to prevent undesired effects associated with solely the induction of mitochondrial biogenesis.

Impact of the Angiotensin-Converting Enzyme (ACE) Inhibitors on the Course of the Acute Respiratory Distress Syndrome (ARDS) Developed During COVID-19 and Other Severe Respiratory Infections Under Hyperferritinemia Conditions: A Cohort Study

Background

Angiotensin-converting enzyme 2 (ACE2) is not only the entry route of SARS-CoV-2 infection but also triggers a major mechanism of COVID-19 aggravation by promoting a hyperinflammatory state, leading to lung injury, hematological and immunological dysregulation. The impact of ACE2 inhibitors on the course of COVID-19 is still unclear. The effect of ACE2 inhibitors on the course of acute respiratory distress syndrome (ARDS) during COVID-19 and other severe respiratory infections in conditions of hyperferritinemia (HF) was investigated.

Methods

A cohort study of critically ill patients with COVID-19 and other respiratory diseases (widespread infection, pneumonia) who underwent treatment in The Critical Care Unit of the First University Clinic (Tbilisi, Georgia) during the 2020-2021 years was conducted. The impact of the ACE2 inhibitors on the course of the ARDS developed during COVID-19 and other severe respiratory infections in conditions of different severity of HF was evaluated.

Results

In COVID-19-infected (I) and uninfected (II) patients with ARDS, ACE2 inhibitors reduce the levels of Ang II, C reactive protein (CRP) and D-dimer (I: from 1508.07  ±  26.68 to 48.51  ±  24.35, from 233.92  ±  13.02 to 198.12  ±  11.88, from 7.88  ±  0.47 to 6.28  ±  0.43; II: from 1000.14  ±  149.49 to 46.23  ±  88.21, 226.48  ±  13.81 to 183.52  ±  17.32, from 6.39  ±  0.58 to 5.48  ±  0.69) at moderate HF and Ang II, CRP levels (I: from 1845.89  ±  89.37 to 49.64  ±  51.05, from 209.28  ±  14.41 to 175.37  ±  9.84; II: from 1753.29  ±  65.95 to 49.76  ±  55.74, 287.10  ±  20.50 to 214.71  ±  17.32) at severe HF, reduce interleukin-6 (IL-6) expression at moderate HF (I: from 1977.23  ±  354.66 to 899.36  ±  323.76) and cause reduction of pCO2 index at severe HF (I: from 69.80  ±  3.22 to 60.44  ±  2.20) in COVID-19-infected patients.

Conclusion

Study results show that the ACE2 inhibitors play an important role in the regulation of inflammatory processes in both COVID-19-infected and uninfected patients with ARDS. ACE2 inhibitors decrease immunological disorders, inflammation, and lung alveoli dysfunction, especially in COVID-19-infected patients.

Whole campus wastewater surveillance of SARS-CoV-2 for COVID-19 outbreak management

In this long-term study (eight months), a wastewater-based epidemiology program was initiated as a decision support tool for the detection and containment of COVID-19 spread in the Technion campus. The on-campus students' accommodations (∼3,300 residents) were divided into housing clusters and monitored through wastewater SARS-CoV-2 surveillance in 10 manholes. Results were used to create a 'traffic-light' scheme allowing the Technion's COVID-19 task force to track COVID-19 spatiotemporal spread on the campus, and consequently, contain it before high morbidity levels develop. Of the 523 sewage samples analysed, 87.4% were negative for SARS-CoV-2 while 11.5% were positive, corroborating morbidity information the COVID-19 task force had. For 7.6% of the SARS-CoV-2 positive samples, the task force had no information about positive resident/s. In these events, new cases were identified after the relevant residents were clinically surge tested for COVID-19. Hence, in these instances, wastewater surveillance provided early warning helping to secure the health of the campus residents by minimising COVID-19 spread. The inflammation biomarker ferritin levels in SARS-CoV-2 positive sewage samples were significantly higher than in negative ones. This may indicate that in the future, ferritin (and other biomarkers) concentrations in wastewater could serve as indicators of infectious and inflammatory disease outbreaks.

Understanding the Potential and Risk of Bacterial Siderophores in Cancer

Siderophores are iron chelating molecules produced by nearly all organisms, most notably by bacteria, to efficiently sequester the limited iron that is available in the environment. Siderophores are an essential component of mammalian iron homeostasis and the ongoing interspecies competition for iron. Bacteria produce a broad repertoire of siderophores with a canonical role in iron chelation and the capacity to perform versatile functions such as interacting with other microbes and the host immune system. Siderophores are a vast area of untapped potential in the field of cancer research because cancer cells demand increased iron concentrations to sustain rapid proliferation. Studies investigating siderophores as therapeutics in cancer generally focused on the role of a few siderophores as iron chelators; however, these studies are limited and some show conflicting results. Moreover, siderophores are biologically conserved, structurally diverse molecules that perform additional functions related to iron chelation. Siderophores also have a role in inflammation due to their iron acquisition and chelation properties. These diverse functions may contribute to both risks and benefits as therapeutic agents in cancer. The potential of siderophore-mediated iron and bacterial modulation to be used in the treatment of cancer warrants further investigation. This review discusses the wide range of bacterial siderophore functions and their utilization in cancer treatment to further expand their functional relevance in cancer detection and treatment.

Physiology and Inflammation Driven Pathophysiology of Iron Homeostasis-Mechanistic Insights into Anemia of Inflammation and Its Treatment

Anemia is very common in patients with inflammatory disorders. Its prevalence is associated with severity of the underlying disease, and it negatively affects quality of life and cardio-vascular performance of patients. Anemia of inflammation (AI) is caused by disturbances of iron metabolism resulting in iron retention within macrophages, a reduced erythrocyte half-life, and cytokine mediated inhibition of erythropoietin function and erythroid progenitor cell differentiation. AI is mostly mild to moderate, normochromic and normocytic, and characterized by low circulating iron, but normal and increased levels of the storage protein ferritin and the iron hormone hepcidin. The primary therapeutic approach for AI is treatment of the underlying inflammatory disease which mostly results in normalization of hemoglobin levels over time unless other pathologies such as vitamin deficiencies, true iron deficiency on the basis of bleeding episodes, or renal insufficiency are present. If the underlying disease and/or anemia are not resolved, iron supplementation therapy and/or treatment with erythropoietin stimulating agents may be considered whereas blood transfusions are an emergency treatment for life-threatening anemia. New treatments with hepcidin-modifying strategies and stabilizers of hypoxia inducible factors emerge but their therapeutic efficacy for treatment of AI in ill patients needs to be evaluated in clinical trials.

Iron Acquisition Systems of Gram-negative Bacterial Pathogens Define TonB-Dependent Pathways to Novel Antibiotics

Iron is an indispensable metabolic cofactor in both pro- and eukaryotes, which engenders a natural competition for the metal between bacterial pathogens and their human or animal hosts. Bacteria secrete siderophores that extract Fe3+ from tissues, fluids, cells, and proteins; the ligand gated porins of the Gram-negative bacterial outer membrane actively acquire the resulting ferric siderophores, as well as other iron-containing molecules like heme. Conversely, eukaryotic hosts combat bacterial iron scavenging by sequestering Fe3+ in binding proteins and ferritin. The variety of iron uptake systems in Gram-negative bacterial pathogens illustrates a range of chemical and biochemical mechanisms that facilitate microbial pathogenesis. This document attempts to summarize and understand these processes, to guide discovery of immunological or chemical interventions that may thwart infectious disease.

Intravenous iron supplementation after liver surgery: Impact on anemia, iron, and hepcidin levels-a randomized controlled trial

BACKGROUND

Anemia is a recognized risk factor for perioperative related morbidity and mortality and is frequently reported in liver surgeries with an estimated incidence of 32%. We aim to assess the impact of intravenous iron administration in the immediate postoperative period on anemia and iron status as well as to determine the kinetics of hepcidin after liver surgery.

METHODS

The HepciFer trial, a randomized controlled trial, included 50 patients undergoing liver surgery. In accordance with the randomization process, patients received either ferric carboxymaltose (15 mg/kg, maximum 1 g) or placebo 4 hours after surgery.

RESULTS

The mean hemoglobin level, 7 days after surgery, did not differ significantly between the intervention and control group (11.1 ± 1.8 g/dL and 10.4 ± 1.6 g/dL, respectively) with a mean difference of +0.7 g/dL ([95% confidence interval, -0.3 to +1.7], P = .173). Within patients receiving intravenous iron supplementation, none presented biological signs of functional iron deficiency. Hepcidin levels remained significantly higher during the observation period in the intervention group. Inflammatory biomarkers, red blood cells transfusion rate and hospital duration of stay were similar between groups.

CONCLUSION

Intravenous ferric carboxymaltose administration did not result in a significant increase of hemoglobin levels 7 days after surgery. However, this study suggests that intravenous iron supplementation in the immediate postoperative settings prevents functional iron deficiency. Intravenous iron supplementation overcame the hepcidin-mediated blockade of iron absorption and should be considered as the preferred route of administration in the postoperative period.

Obesity as a Risk Factor for Severe COVID-19 and Complications: A Review

Emerging data suggest that obesity is a major risk factor for the progression of major complications such as acute respiratory distress syndrome (ARDS), cytokine storm and coagulopathy in COVID-19. Understanding the mechanisms underlying the link between obesity and disease severity as a result of SARS-CoV-2 infection is crucial for the development of new therapeutic interventions and preventive measures in this high-risk group. We propose that multiple features of obesity contribute to the prevalence of severe COVID-19 and complications. First, viral entry can be facilitated by the upregulation of viral entry receptors, like angiotensin-converting enzyme 2 (ACE2), among others. Second, obesity-induced chronic inflammation and disruptions of insulin and leptin signaling can result in impaired viral clearance and a disproportionate or hyper-inflammatory response, which together with elevated ferritin levels can be a direct cause for ARDS and cytokine storm. Third, the negative consequences of obesity on blood coagulation can contribute to the progression of thrombus formation and hemorrhage. In this review we first summarize clinical findings on the relationship between obesity and COVID-19 disease severity and then further discuss potential mechanisms that could explain the risk for major complications in patients suffering from obesity.

Cutaneous Manifestations in Patients With COVID-19: Clinical Characteristics and Possible Pathophysiologic Mechanisms

The rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections soon led to a pandemic with serious health, economic, political, and cultural repercussions across the globe. The disease caused by SARS-CoV-2, coronavirus disease 2019 (COVID-19), is a multisystemic disease that requires a multidisciplinary approach involving specialists from all fields and levels of care. In this article, we review the literature on the diverse cutaneous manifestations associated with COVID-19. We also describe the pathophysiologic mechanisms proposed to date and their possible association with these manifestations. Finally, we propose a system for classifying the cutaneous manifestations of COVID-19 according to their underlying pathophysiologic mechanisms and prognosis.

Cutaneous Manifestations in Patients With COVID-19: Clinical Characteristics and Possible Pathophysiologic Mechanisms

The rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections soon led to a pandemic with serious health, economic, political, and cultural repercussions across the globe. The disease caused by SARS-CoV-2, coronavirus disease 2019 (COVID-19), is a multisystemic disease that requires a multidisciplinary approach involving specialists from all fields and levels of care. In this article, we review the literature on the diverse cutaneous manifestations associated with COVID-19. We also describe the pathophysiologic mechanisms proposed to date and their possible association with these manifestations. Finally, we propose a system for classifying the cutaneous manifestations of COVID-19 according to their underlying pathophysiologic mechanisms and prognosis.

Role of inflammatory markers in corona virus disease (COVID-19) patients: A review

IMPACT STATEMENT

In late 2019, a novel virus called SARS-CoV-2, expanded globally from Wuhan, China and was declared a pandemic on 11 March 2020 by the WHO. The mechanism of virus entry inside the host cell depends upon the cellular proteases including cathepsins, HAT, and TMPRSS2, which splits up the spike protein and causes further penetration. MERS coronavirus uses DPP4, while coronavirus HCoV-NL63 and SARS-CoV and SARS-CoV-2 employ ACE-2 as the key receptor. Cytokine storm syndrome was analyzed in critically ill nCOVID-19 patients and it is presented with high inflammatory mediators, systemic inflammation, and multiple organ failure. Among various inflammatory mediators, the level of interleukins (IL-2, IL-7, IL-10), G-CSF, MIP1A, MCP1, and TNF-α was reported to be higher in critically ill patients. Understanding this molecular mechanism of ILs, T cells, and dendritic cells will be helpful to design immunotherapy and novel drugs for the treatment of nCOVID-19 infection.

Mathematical Modelling Using Predictive Biomarkers for the Outcome of Canine Leishmaniasis upon Chemotherapy

Prediction parameters of possible outcomes of canine leishmaniasis (CanL) therapy might help with therapeutic decisions and animal health care. Here, we aimed to develop a diagnostic method with predictive value by analyzing two groups of dogs with CanL, those that exhibited a decrease in parasite load upon antiparasitic treatment (group: responders) and those that maintained high parasite load despite the treatment (group: non-responders). The parameters analyzed were parasitic load determined by q-PCR, hemogram, serum biochemistry and immune system-related gene expression signature. A mathematical model was applied to the analysis of these parameters to predict how efficient their response to therapy would be. Responder dogs restored hematological and biochemical parameters to the reference values and exhibited a Th1 cell activation profile with a linear tendency to reach mild clinical alteration stages. Differently, non-responders developed a mixed Th1/Th2 response and exhibited markers of liver and kidney injury. Erythrocyte counts and serum phosphorus were identified as predictive markers of therapeutic response at an early period of assessment of CanL. The results presented in this study are highly encouraging and may represent a new paradigm for future assistance to clinicians to interfere precociously in the therapeutic approach, with a more precise definition in the patient's prognosis.

Iron Administration, Infection, and Anemia Management in CKD: Untangling the Effects of Intravenous Iron Therapy on Immunity and Infection Risk

Patients with chronic kidney disease (CKD) are at increased risk for infection, attributable to immune dysfunction, increased exposure to infectious agents, loss of cutaneous barriers, comorbid conditions, and treatment-related factors (eg, hemodialysis and immunosuppressant therapy). Because iron plays a vital role in pathogen reproduction and host immunity, it is biologically plausible that intravenous iron therapy and/or iron deficiency influence infection risk in CKD. Available data from preclinical experiments, observational studies, and randomized controlled trials are summarized to explore the interplay between intravenous iron and infection risk among patients with CKD, particularly those receiving maintenance hemodialysis. The current evidence base, including data from a recent randomized controlled trial, suggests that proactive judicious use of intravenous iron (in a manner that minimizes the accumulation of non-transferrin-bound iron) beneficially replaces iron stores while avoiding a clinically relevant effect on infection risk. In the absence of an urgent clinical need, intravenous iron therapy should be avoided in patients with active infection. Although serum ferritin concentration and transferrin saturation can help guide clinical decision making about intravenous iron therapy, definition of an optimal iron status and its precise determination in individual patients remain clinically challenging in CKD and warrant additional study.

Increased Iron Availability Aggravates the Infection of Escherichia coli O157:H7 in Mice

Iron plays an important role both in bacterial pathogenicity and in host defense mechanisms, which has frequently been underestimated. The primary purpose of this study was to investigate the influence of iron supplementation on the progression of bacterial infection. We used mice as an experimental model to supplement iron after Escherichia coli (E. coli) O157:H7 infection and found that iron supplementation exacerbated clinical symptoms of bacterial infection by increasing mortality and reducing body weight. Iron supplementation promoted the colonization of bacteria and enhanced inflammatory responses by increasing C-reaction protein level and the phagocytic capacity of PBMCs, as well as upregulating the expression of TNF-α and IL-1β in E. coli O157:H7-challenged mice. In vitro cell experiment confirmed that an excess of iron would enhance the growth of E. coli O157:H7 and worsen the outcome of bacterial infection. Therefore, it is certainly plausible that iron supplementation in bacterial infection may worsen rather than improve host outcome.

Monitoring of iron deficiency in calves by determination of serum ferritin in comparison with serum iron: A preliminary study

Background

Iron deficiency can cause anemia in calves and is, therefore, of economic importance for the cattle industry. Low iron levels are commonly caused by feeding whole milk without the addition of dietary supplements and led to the most frequent cause of anemia in calves. Other reasons for the development of anemia include congenital iron deficiency, malnutrition, bleeding ulcers, or bloodsucking parasites.

Aim:

This study compared laboratory parameters that are commonly used to diagnose iron deficiency anemia in calves. Additionally, serum ferritin values were compared amongst calves fed different milk meals.

Methods:

For this purpose, blood samples from 40 calves were analyzed for different hematologic parameters as well as the content of copper, glutathione peroxidase, serum iron, and serum ferritin.

Results:

Eight calves showed decreased hemoglobin and hematocrit values and a significantly lower number of erythrocytes compared with non-anemic calves. Interestingly, 19 of 40 calves had a low serum iron. Considering their serum ferritin levels, only 14 calves, including six calves with both low iron and low ferritin levels, were classified as iron deficient. No direct correlation between serum ferritin and serum iron was detected. Comparing milk diets, more calves fed milk replacer showed reduced levels of ferritin compared with calves fed whole milk.

Conclusion:

Our data indicate that the determination of hemoglobin and serum iron is of limited suitability for the diagnosis of iron deficiency in calves. We suggest that the determination of serum ferritin should be the preferred parameter, since serum iron levels are subject to physiological fluctuation and a deficiency can be caused by inflammation or neoplastic diseases.

Molecular mechanisms of Vibrio parahaemolyticus pathogenesis

Vibrio parahaemolyticus is a Gram-negative halophilic bacterium that is mainly distributed in the seafood such as fish, shrimps and shellfish throughout the world. V. parahaemolyticus can cause diseases in marine aquaculture, leading to huge economic losses to the aquaculture industry. More importantly, it is also the leading cause of seafood-borne diarrheal disease in humans worldwide. With the development of animal model, next-generation sequencing as well as biochemical and cell biological technologies, deeper understanding of the virulence factors and pathogenic mechanisms of V. parahaemolyticus has been gained. As a globally transmitted pathogen, the pathogenicity of V. parahaemolyticus is closely related to a variety of virulence factors. This article comprehensively reviewed the molecular mechanisms of eight types of virulence factors: hemolysin, type III secretion system, type VI secretion system, adhesion factor, iron uptake system, lipopolysaccharide, protease and outer membrane proteins. This review comprehensively summarized our current understanding of the virulence factors in V. parahaemolyticus, which are potentially new targets for the development of therapeutic and preventive strategies.

The 'Checkmate' for Iron Between Human Host and Invading Bacteria: Chess Game Analogy

Iron is an essential nutrient for all living organisms with critical roles in many biological processes. The mammalian host maintains the iron requirements by dietary intake, while the invading pathogenic bacteria compete with the host to obtain those absorbed irons. In order to limit the iron uptake by the bacteria, the human host employs numerous iron binding proteins and withholding defense mechanisms that capture iron from the microbial invaders. To counteract, the bacteria cope with the iron limitation imposed by the host by expressing various iron acquisition systems, allowing them to achieve effective iron homeostasis. The armamentarium used by the human host and invading bacteria, leads to the dilemma of who wins the ultimate war for iron.

Putative Iron Acquisition Systems in Stenotrophomonas maltophilia

Iron has been shown to regulate biofilm formation, oxidative stress response and several pathogenic mechanisms in Stenotrophomonas maltophilia. Thus, the present study is aimed at identifying various iron acquisition systems and iron sources utilized during iron starvation in S. maltophilia. The annotations of the complete genome of strains K279a, R551-3, D457 and JV3 through Rapid Annotations using Subsystems Technology (RAST) revealed two putative subsystems to be involved in iron acquisition: the iron siderophore sensor and receptor system and the heme, hemin uptake and utilization systems/hemin transport system. Screening for these acquisition systems in S. maltophilia showed the presence of all tested functional genes in clinical isolates, but only a few in environmental isolates. NanoString nCounter Elements technology, applied to determine the expression pattern of the genes under iron-depleted condition, showed significant expression for FeSR (6.15-fold), HmuT (12.21-fold), Hup (5.46-fold), ETFb (2.28-fold), TonB (2.03-fold) and Fur (3.30-fold). The isolates, when further screened for the production and chemical nature of siderophores using CAS agar diffusion (CASAD) and Arnows's colorimetric assay, revealed S. maltophilia to produce catechol-type siderophore. Siderophore production was also tested through liquid CAS assay and was found to be greater in the clinical isolate (30.8%) compared to environmental isolates (4%). Both clinical and environmental isolates utilized hemoglobin, hemin, transferrin and lactoferrin as iron sources. All data put together indicates that S. maltophilia utilizes siderophore-mediated and heme-mediated systems for iron acquisition during iron starvation. These data need to be further confirmed through several knockout studies.

Clinical consequences of iron overload in patients with myelodysplastic syndromes: the case for iron chelation therapy

INTRODUCTION

Patients with myelodysplastic syndromes (MDS) are at increased risk of iron overload due to ineffective erythropoiesis and chronic transfusion therapy. The clinical consequences of iron overload include cardiac and/or hepatic failure, endocrinopathies, and infection risk. Areas covered: Iron chelation therapy (ICT) can help remove excess iron and ultimately reduce the clinical consequences of iron overload. The authors reviewed recent (last five years) English-language articles from PubMed on the topic of iron overload-related complications and the use of ICT (primarily deferasirox) to improve outcomes in patients with MDS. Expert commentary: While a benefit of ICT has been more firmly established in other transfusion-dependent conditions, such as thalassemia, its role in reducing iron overload in MDS remains controversial due to the lack of prospective controlled data demonstrating a survival benefit. Orally administered chelation agents (e.g. deferasirox) are now available, and observational and/or retrospective data support a survival benefit of using ICT in MDS. The placebo-controlled TELESTO trial (NCT00940602) is currently examining the use of deferasirox in MDS patients with iron overload, and is evaluating specifically whether use of ICT to alleviate iron overload can also reduce iron overload-related complications in MDS and improve survival.

Risk Factors for Surgical Site Infection Following Lower Limb Arthroplasty: A Retrospective Cohort Analysis of 3932 Lower Limb Arthroplasty Procedures in a High Volume Arthroplasty Unit

BACKGROUND

Surgical site infection (SSI) is a debilitating complication of lower limb arthroplasty with significant morbidity and increased costs. Numerous risk factors are associated with SSI.

METHODS

In an effort to identify novel risk factors for SSI, we undertook a retrospective cohort study of 1832 primary total hip arthroplasties and 2100 primary total knee arthroplasties performed in our high volume arthroplasty unit over a 2-year period.

RESULTS

Two risk factors were identified for SSI following total hip arthroplasty: body mass index ≥30 and peri-operative blood transfusion. Eight risk factors were identified for SSI following total knee arthroplasty: hypertension, peri-operative blood transfusion, skin closure using 2-octyl cyanoacrylate, use of oral steroids, reduced serum mean cell volume, reduced mean cell hemoglobin, elevated serum neutrophil count, and use of warfarin or rivaroxaban for venous thromboembolism prophylaxis.

CONCLUSIONS

Our work proposes a number of previously undocumented risk factors in relation to SSI. Further investigation is required to ascertain the magnitude of their effect.

Hyperferritinemia and inflammation

Understanding of ferritin biology has traditionally centered on its role in iron storage and homeostasis, with low ferritin levels indicative of deficiency and high levels indicative of primary or secondary hemochromatosis. However, further work has shown that iron, redox biology and inflammation are inexorably linked. During infection, increased ferritin levels represent an important host defense mechanism that deprives bacterial growth of iron and protects immune cell function. It may also be protective, limiting the production of free radicals and mediating immunomodulation. Additionally, hyperferritinemia is a key acute-phase reactants, used by clinicians as an indication for therapeutic intervention, aimed at controlling inflammation in high-risk patients. One school of thought maintains that hyperferritinemia is an 'innocent bystander' biomarker of uncontrolled inflammation that can be used to gauge effectiveness of intervention. Other schools of thought maintain that ferritin induction could be a protective negative regulatory loop. Others maintain that ferritin is a key mediator of immune dysregulation, especially in extreme hyperferritinemia, via direct immune-suppressive and pro-inflammatory effects. There is a clear need for further investigation of the role of ferritin in uncontrolled inflammatory conditions both as a biomarker and mediator of disease because its occurrence identifies patients with high mortality risk and its resolution predicts their improved survival.

A temporal proteome dynamics study reveals the molecular basis of induced phenotypic resistance in Mycobacterium smegmatis at sub-lethal rifampicin concentrations

In the last 40 years only one new antitubercular drug has been approved, whilst resistance to current drugs, including rifampicin, is spreading. Here, we used the model organism Mycobacterium smegmatis to study mechanisms of phenotypic mycobacterial resistance, employing quantitative mass spectrometry-based proteomics to investigate the temporal effects of sub-lethal concentrations of rifampicin on the mycobacterial proteome at time-points corresponding to early response, onset of bacteriostasis and early recovery. Across 18 samples, a total of 3,218 proteins were identified from 31,846 distinct peptides averaging 16,250 identified peptides per sample. We found evidence that two component signal transduction systems (e.g. MprA/MprB) play a major role during initial mycobacterial adaptive responses to sub-lethal rifampicin and that, after dampening an initial SOS response, the bacteria supress the DevR (DosR) regulon and also upregulate their transcriptional and translational machineries. Furthermore, we found a co-ordinated dysregulation in haeme and mycobactin synthesis. Finally, gradual upregulation of the M. smegmatis-specific rifampin ADP-ribosyl transferase was observed which, together with upregulation of transcriptional and translational machinery, likely explains recovery of normal growth. Overall, our data indicates that in mycobacteria, sub-lethal rifampicin triggers a concerted phenotypic response that contrasts significantly with that observed at higher antimicrobial doses.

Association between predominantly plant-based diets and iron status in Chinese adults: a cross-sectional analysis

Current evidence of the relationship between diets and Fe status is mostly derived from studies in developed countries with Western diets, which may not be translatable to Chinese with a predominantly plant-based diet. We extracted data that were nationally sampled from the 2009 wave of China Health and Nutrition Survey; dietary information was collected using 24-h recalls combined with a food inventory for 3 consecutive days. Blood samples were collected to quantify Fe status, and log-ferritin, transferrin receptor and Hb were used as Fe status indicators. In total, 2905 (1360 males and 1545 females) adults aged 18–50 years were included for multiple linear regression and stratified analyses. The rates of Fe deficiency and Fe-deficiency anaemia were 1·6 and 0·7 % for males and 28·4 and 10·7 % for females, respectively. As red meat and haem Fe consumption differed about fifteen to twenty times throughout the five groups, divided by quintiles of animal protein intake per 4·2 MJ/d, only Fe status as indicated by log-ferritin (P=0·019) and transferrin receptor (P=0·024) concentrations in males was shown to be higher as intakes of animal foods increased. Log-ferritin was positively associated with intakes of red meat (B=0·3 %, P=0·01) and haem Fe (B=12·3 %, P=0·010) in males and with intake of non-haem Fe in females (B=2·2 %, P=0·024). We conclude that diet has a very limited association with Fe status in Chinese adults consuming a traditional Chinese diet, and a predominantly plant-based diet may not be necessarily responsible for poor Fe status.

Risk stratification for invasive fungal infections in patients with hematological malignancies: SEIFEM recommendations

Invasive fungal infections (IFIs) are an important cause of morbidity and mortality in immunocompromised patients. Patients with hematological malignancies undergoing conventional chemotherapy, autologous or allogeneic hematopoietic stem cell transplantation are considered at high risk, and Aspergillus spp. represents the most frequently isolated micro-organisms. In the last years, attention has also been focused on other rare molds (e.g., Zygomycetes, Fusarium spp.) responsible for devastating clinical manifestations. The extensive use of antifungal prophylaxis has reduced the infections from yeasts (e.g., candidemia) even though they are still associated with high mortality rates. This paper analyzes concurrent multiple predisposing factors that could favor the onset of fungal infections. Although neutropenia is common to almost all hematologic patients, other factors play a key role in specific patients, in particular in patients with AML or allogeneic HSCT recipients. Defining those patients at higher risk of IFIs may help to design the most appropriate diagnostic work-up and antifungal strategy.

Management of iron overload in the Canadian hematology/oncology population: Implications for nursing practice

Red blood cell (RBC) transfusions are vital for many patients with chronic anemias associated with oncologic/hematologic disorders. However, repeated transfusions over time can lead to iron overload, which, if left untreated, can increase the risk of further malignancy and end-organ damage. Nurses and other health care professionals may not be aware of the significant implications of RBC transfusions and iron overload in patients with hematological/oncological disorders. This article was developed by a group of Canadian nurse practitioners and specialized oncology nurses to help improve health care professionals' understanding of iron overload in oncology patients and its associated risks, as well as provide a practical guide for the management of patients receiving treatment for this potentially serious condition.

2,3,7,8-tetrachlorodibenzo-p-dioxin decrease expression of aryl hydrocarbon receptor in peripheral lymphocyte of β-thalassemia major patients

Background:

β-thalassemia major is a hereditary disease with inefficient erythropoiesis. Level of inflammatory cytokine is elevated in these patients. In this study, we investigate the effect of aryl hydrocarbon receptor (AhR) ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), on the expression of inflammatory mediators in β-thalassemia major patient's lymphocytes.

Materials and Methods:

Peripheral blood mononuclear cells of patients and healthy participants was isolated and cultured in favor of lymphocytes increment. Based on the treatment, we divided the cell into four groups. The orders of group's treatments were no treatment, tumor necrosis factor-α (TNF-α) treatment, TNF-α and TCDD treatment, TCDD treatment in Group 1–4, respectively. After cell culture, we extracted the cells RNA and converted them to cDNA. Real-time polymerase chain reaction was performed to assessment relative expression of caspase-1, NLRP3, and AhR. We compared all patient groups with equal healthy (control) groups.

Results:

Results showed that expression of caspase-1 in patients (Groups 1 and 2) was significantly lower than healthy individuals (P < 0.05). Although, no significant difference was found (Groups 1, 2, and control) in AhR gene expression (P > 0.05). Expression of AhR in other groups of patients (3 and 4) was significantly lower than control groups (P < 0.05). Expression of caspase-1 in Group 4 was significantly larger than the control group (P < 0.001).

Conclusions:

We show here that chronic inflammation decrease caspase-1 expression and exposure of human lymphocytes to TCDD promote caspase-1 expression. Furthermore, activation of AhR with TCDD decreases AhR expression in lymphocytes of β-thalassemia major disease.

A multicenter, randomized clinical trial of IV iron supplementation for anemia of traumatic critical illness*

OBJECTIVE

To evaluate the efficacy of IV iron supplementation of anemic, critically ill trauma patients.

DESIGN

Multicenter, randomized, single-blind, placebo-controlled trial.

SETTING

Four trauma ICUs.

PATIENTS

Anemic (hemoglobin < 12 g/dL) trauma patients enrolled within 72 hours of ICU admission and with an expected ICU length of stay of more than or equal to 5 days.

INTERVENTIONS

Randomization to iron sucrose 100 mg IV or placebo thrice weekly for up to 2 weeks.

MEASUREMENTS AND MAIN RESULTS

A total of 150 patients were enrolled. Baseline iron markers were consistent with functional iron deficiency: 134 patients (89.3%) were hypoferremic, 51 (34.0%) were hyperferritinemic, and 64 (42.7%) demonstrated iron-deficient erythropoiesis as evidenced by an elevated erythrocyte zinc protoporphyrin concentration. The median baseline transferrin saturation was 8% (range, 2-58%). In the subgroup of patients who received all six doses of study drug (n = 57), the serum ferritin concentration increased significantly for the iron as compared with placebo group on both day 7 (808.0 ng/mL vs 457.0 ng/mL, respectively, p < 0.01) and day 14 (1,046.0 ng/mL vs 551.5 ng/mL, respectively, p < 0.01). There was no significant difference between groups in transferrin saturation, erythrocyte zinc protoporphyrin concentration, hemoglobin concentration, or packed RBC transfusion requirement. There was no significant difference between groups in the risk of infection, length of stay, or mortality.

CONCLUSIONS

Iron supplementation increased the serum ferritin concentration significantly, but it had no discernible effect on transferrin saturation, iron-deficient erythropoiesis, hemoglobin concentration, or packed RBC transfusion requirement. Based on these data, routine IV iron supplementation of anemic, critically ill trauma patients cannot be recommended (NCT 01180894).

Salmonella adhesion, invasion and cellular immune responses are differentially affected by iron concentrations in a combined in vitro gut fermentation-cell model

In regions with a high infectious disease burden, concerns have been raised about the safety of iron supplementation because higher iron concentrations in the gut lumen may increase risk of enteropathogen infection. The aim of this study was to investigate interactions of the enteropathogen Salmonella enterica ssp. enterica Typhimurium with intestinal cells under different iron concentrations encountered in the gut lumen during iron deficiency and supplementation using an in vitro colonic fermentation system inoculated with immobilized child gut microbiota combined with Caco-2/HT29-MTX co-culture monolayers. Colonic fermentation effluents obtained during normal, low (chelation by 2,2'-dipyridyl) and high iron (26.5 mg iron/L) fermentation conditions containing Salmonella or pure Salmonella cultures with similar iron conditions were applied to cellular monolayers. Salmonella adhesion and invasion capacity, cellular integrity and immune response were assessed. Under high iron conditions in pure culture, Salmonella adhesion was 8-fold increased compared to normal iron conditions while invasion was not affected leading to decreased invasion efficiency (-86%). Moreover, cellular cytokines IL-1β, IL-6, IL-8 and TNF-α secretion as well as NF-κB activation in THP-1 cells were attenuated under high iron conditions. Low iron conditions in pure culture increased Salmonella invasion correlating with an increase in IL-8 release. In fermentation effluents, Salmonella adhesion was 12-fold and invasion was 428-fold reduced compared to pure culture. Salmonella in high iron fermentation effluents had decreased invasion efficiency (-77.1%) and cellular TNF-α release compared to normal iron effluent. The presence of commensal microbiota and bacterial metabolites in fermentation effluents reduced adhesion and invasion of Salmonella compared to pure culture highlighting the importance of the gut microbiota as a barrier during pathogen invasion. High iron concentrations as encountered in the gut lumen during iron supplementation attenuated Salmonella invasion efficiency and cellular immune response suggesting that high iron concentrations alone may not lead to an increased Salmonella invasion.

Metabolic pathways related to oxidative stress in patients with hemoglobin h disease and iron overload

BACKGROUND

Iron overload is a major complication in patients with hemoglobin H (Hb H) disease and causes damage of tissues.

METHODS

We investigated 26 Hb H patients and 75 controls to evaluate their oxidative stress and antioxidant statuses.

RESULTS

There were significantly increased levels of superoxide anion in leucocytes, nitrite (NO2-), and malondialdehyde (MDA) in plasma, and activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GRx) and oxidized glutathione (GSSG) in erythrocytes, decreased levels of nitrate (NO3-) and vitamin C in plasma, and reduced glutathione (GSH) in erythrocytes, in addition to the abnormal iron status in the patients when compared with those in the controls. Meanwhile, levels of serum ferritin were positively correlated with serum iron, plasma MDA, and erythrocyte SOD in the patients. In addition, the activities of SOD were positively correlated with those of GPx and GRx, and the levels of GSSG and MDA, but negatively correlated with those of GSH. Furthermore, the levels of MDA were negatively correlated those of vitamin C.

CONCLUSIONS

These results demonstrate the presence of oxidative stress and decreased levels of antioxidants; moreover, the related metabolic antioxidant pathway is active in Hb H patients with iron overload.

Infection risk with bolus versus maintenance iron supplementation in hemodialysis patients

Intravenous iron may promote bacterial growth and impair host defense, but the risk of infection associated with iron supplementation is not well defined. We conducted a retrospective cohort study of hemodialysis patients to compare the safety of bolus dosing, which provides a large amount of iron over a short period of time on an as-needed basis, with maintenance dosing, which provides smaller amounts of iron on a regular schedule to maintain iron repletion. Using clinical data from 117,050 patients of a large US dialysis provider merged with data from Medicare's ESRD program, we estimated the effects of iron dosing patterns during repeated 1-month exposure periods on risks of mortality and infection-related hospitalizations during the subsequent 3 months. Of 776,203 exposure/follow-up pairs, 13% involved bolus dosing, 49% involved maintenance dosing, and 38% did not include exposure to iron. Multivariable additive risk models found that patients receiving bolus versus maintenance iron were at increased risk of infection-related hospitalization (risk difference [RD], 25 additional events/1000 patient-years; 95% confidence interval [CI], 16 to 33) during follow-up. Risks were largest among patients with a catheter (RD, 73 events/1000 patient-years; 95% CI, 48 to 99) and a recent infection (RD, 57 events/1000 patient-years; 95% CI, 19 to 99). We also observed an association between bolus dosing and infection-related mortality. Compared with no iron, maintenance dosing did not associate with increased risks for adverse outcomes. These results suggest that maintenance iron supplementation may result in fewer infections than bolus dosing, particularly among patients with a catheter.

Risks for infection in patients with myelodysplasia and acute leukemia

PURPOSE OF REVIEW

The aim of the present review is to analyze the main parameters that may influence the onset of bacterial, fungal and viral infections in patients with myelodysplastic syndromes, acute myeloid leukemia and acute lymphoid leukemia.

RECENT FINDINGS

The identification of factors influencing the onset of infections in high-risk patients is becoming one of the most important strategies to identify those patients who would really benefit from prophylactic and timely treatment. During the past few years several studies have been conducted to evaluate the impact of risk factors that may influence both the onset and the outcome of infections. The role of some of them is well defined (i.e. neutropenia, central venous catheters), whereas other factors are now emerging as new possible causative factors (i.e. iron overload, hospitalization).

SUMMARY

Many factors have to be considered when evaluating the infectious risk in hematological patients. In current clinical practice the good knowledge of these factors may favor a better management of infectious risk, with a reduction of mortality rate.

Infections in myelodysplastic syndromes

Myelodysplastic syndromes are associated with a risk of severe infections. While neutropenia is likely to be the main predisposing factor, several other immune defects have been reported, including impaired neutrophil function, B-, T- and NK-cell defects and the possible consequences of iron overload due to red blood cell transfusions. The advanced age of most patients, their frequent comorbidities, and the fact that drugs such as hypomethylating agents and lenalidomide, which are effective in myelodysplastic syndromes but can transiently worsen neutropenia, may increase the risk of infection and their severity in this context. The majority of infections in myelodysplastic syndromes are bacterial, while the incidence of fungal infections is not well known and viral infections seem to be rare. No prophylactic measures against infections have demonstrated efficacy in myelodysplastic syndromes. However, pending more data, we propose here some recommendations for the management of patients with myelodysplastic syndromes. In the future, an important contribution can be made by prospective trials testing the efficacy of prophylactic and therapeutic approaches to infection in these patients, especially in the context of the new drugs available for myelodysplastic syndromes.

Efficacy and toxicity of intravenous iron in a mouse model of critical care anemia*

OBJECTIVE

Anemia is common in critically ill patients, due to inflammation and blood loss. Anemia can be associated with iron deficiency and low serum hepcidin levels. However, iron administration in this setting remains controversial because of its potential toxicity, including oxidative stress induction and sepsis facilitation. The objective of this work was to determine the efficacy and toxicity of iron administration using a mouse model mimicking critical care anemia as well as a model of acute septicemia.

DESIGN

Prospective, randomized, open label controlled animal study.

SETTING

University-based research laboratory.

SUBJECTS

C57BL/6 and OF1 mice.

INTERVENTIONS

Intraperitoneal injection of zymosan inducing generalized inflammation in C57BL/6 mice, followed in our full model by repeated phlebotomies. A dose equivalent to 15 mg/kg of ferric carboxymaltose was injected intravenously on day 5. To assess the toxicity of iron in a septicemia model, OF1 mice were simultaneously injected with iron and different Escherichia coli strains.

MEASUREMENTS AND MAIN RESULTS

To investigate the effect of iron on oxidative stress, we measured reactive oxygen species production in the blood using luminol-amplified chemiluminescence and superoxide dismutase 2 messenger RNA levels in the liver. These markers of oxidative stress were increased after iron administration in control mice but not in zymosan-treated mice. Liver catalase messenger RNA levels decreased in iron-treated control mice. Iron administration was not associated with increased mortality in the septicemia model or in the generalized inflammation model. Iron increased hemoglobin levels in mice fed with a low iron diet and subjected to phlebotomies and zymosan 2 wks after treatment administration.

CONCLUSIONS

Adverse effects of intravenous iron supplementation by ferric carboxymaltose seem to be minimal in our animal models. Furthermore, iron appears to be effective in correcting anemia, despite inflammation. Studies of efficacy and safety of iron in critically ill patients are warranted.

Randomized, double-blind, placebo-controlled trial of effects of enteral iron supplementation on anemia and risk of infection during surgical critical illness

BACKGROUND

Critical illness is characterized by hypoferremia, iron-deficient erythropoiesis (IDE), and anemia. The relative risks and benefits of iron supplementation in this setting are unknown.

METHODS

Anemic, critically ill surgical patients with an expected intensive care unit length of stay (ULOS) >or= 5 days were randomized to either enteral iron supplementation (ferrous sulfate 325 mg three times daily) or placebo until hospital discharge. Outcomes included hematocrit, iron markers (i.e., serum concentrations of iron, ferritin, and erythrocyte zinc protoporphyrin [eZPP]), red blood cell (RBC) transfusion, transfusion rate (mL RBC/study day), nosocomial infection, antibiotic days, study length of stay (LOS), ULOS, and death. Iron-deficient erythropoiesis was defined as an elevated eZPP concentration.

RESULTS

Two hundred patients were randomized; 97 received iron, and 103 received placebo. Socio-demographics, baseline acuity, hematocrit, and iron markers were similar in the two groups. No differences were observed between the iron and placebo groups with respect to either hematocrit or iron markers following up to 28 days. However, patients treated with iron were significantly less likely to receive an RBC transfusion (29.9% vs. 44.7%, respectively; p = 0.03) and had a significantly lower transfusion rate (22.0 mL/day vs. 29.9 mL/day; p = 0.03). Subgroup analysis revealed that these differences were observed in patients with baseline IDE only. Iron and placebo groups did not differ with respect to incidence of infection (46.8% vs. 48.9%; p = 0.98), antibiotic days (14 vs. 16; p = 0.45), LOS (14 vs. 16 days; p = 0.24), ULOS (12 vs. 14 days; p = 0.69), or mortality rate (9.4% vs. 9.9%; p = 0.62).

CONCLUSIONS

Enteral iron supplementation of anemic, critically ill surgical patients does not increase the risk of infection and may benefit those with baseline IDE by decreasing the risk of RBC transfusion. A trial comparing enteral and parenteral iron supplementation in this setting is warranted (ClinicalTrials.gov number, NCT00450177).

Comparison of darbepoetin alfa and epoetin alfa in the management of anemia of critical illness

STUDY OBJECTIVE

To compare the effectiveness of darbepoetin alfa with epoetin alfa (recombinant human erythropoietin [rHuEPO]) for achieving transfusion independence and increasing hemoglobin concentrations in critically ill patients.

DESIGN

Retrospective, descriptive study.

SETTING

Level I trauma center intensive care units.

PATIENTS

Seventy-two patients who spent at least 3 days in the cardio-thoracic, medical, or surgery-trauma intensive care units and received at least one weekly dose of rHuEPO 40,000 units (33 patients) or darbepoetin alfa 100 microg (39 patients).

MEASUREMENTS AND MAIN RESULTS

Number of rHuEPO and darbepoetin alfa doses, hemoglobin concentrations, and cumulative number of transfusions were recorded for up to 28 days after the first dose was given, and the data were statistically analyzed. Beginning a median of 10 days after the patients were admitted to the intensive care unit, they received a median of 3.5 doses of darbepoetin alfa or 4 doses of rHuEPO. Mean hemoglobin concentrations at which treatment with darbepoetin alfa and rHuEPO were started were 8 and 8.2 g/dl, respectively (p=0.41). Transfusion independence was achieved in 44% of patients in the darbepoetin alfa group compared with 36% of patients in the rHuEPO group (p=0.63). Patients in both groups received a mean of 2.7 units of packed red blood cells during the 28-day study period. The mean change in hemoglobin levels from baseline over time did not significantly differ between groups (p=0.75).

CONCLUSIONS

Patients receiving darbepoetin alfa 100 microg/week and those receiving rHuEPO 40,000 units/week for anemia of critical illness achieved similar rates of transfusion independence and increases in hemoglobin concentrations from baseline at 28 days. Compared with previously published studies, erythropoietic agents were administered late in the course of critical illness in response to low hemoglobin concentrations.

Intravenous Iron Following Cardiac Surgery Does Not Increase the Infection Rate

BACKGROUND

Intravenous iron (FeIV) has been used increasingly, alone or in combination with recombinant erythropoietin, to promote red cell production as part of a blood conservation program. Given the important role that iron plays in the growth of bacteria, it has been hypothesized that this use of FeIV may promote surgical site infection. However, this hypothesis has not yet been tested appropriately. To assess this hypothesis, postoperative infection rates in patients undergoing cardiothoracic surgery were analyzed.

METHODS

Data were collected on 863 patients undergoing cardiopulmonary bypass surgery in 2001. Patients were either enrolled voluntarily in a blood conservation program in which they received either postoperative FeIV and erythropoietin (n=302), as indicated, or blood transfusions and no FeIV (n=561), as indicated, to correct postoperative anemia. Infections were defined according to the U.S. Centers for Disease Control and Prevention guidelines.

RESULTS

Thirty-nine infections developed. The overall infection rate was 4.52%, with an infection rate of 3.97% in the iron-treated group (n=12) and a rate of 4.81% in the untreated group (n=27). When the impact of gender, age, diabetes mellitus, operating time, type of surgery, and blood transfusions were controlled for, FeIV did not increase the risk of infection (odds ratio of 1.031 for each increment of 125 mg of FeIV; 95% confidence interval 0.908, 1.170; p=0.64).

CONCLUSIONS

There was no impact of FeIV on the subsequent infection rate in a cardiac surgery patient cohort, indicating its safety for use in the postoperative setting.

Diagnosis and management of iron-related anemias in critical illness

OBJECTIVE

To review of the prevalence, pathogenesis, diagnosis, and management of iron (Fe)-related anemias in critical illness.

DATA SOURCE

A MEDLINE/PubMed search from 1966 to October 2005 was conducted. References from relevant articles were manually cross-referenced with additional original articles, review articles, correspondence, and chapters from selected textbooks.

DATA EXTRACTION AND SYNTHESIS

Both Fe metabolism and erythropoiesis are affected by the inflammatory response that accompanies critical illness. As a result, many critically ill patients develop the anemia of inflammation, which may be compounded by an underlying Fe deficiency. Most commonly available markers of total body Fe detect Fe deficiency unreliably in the setting of inflammation. Among these tests, the serum transferrin receptor assay is relatively accurate in reflecting total body Fe, regardless of inflammation. Treatment options for Fe-related anemias in critical illness include Fe replacement and recombinant human erythropoietin therapy. The decision to implement these therapies is complex and centers on a critical evaluation of ability to affect anemia, morbidity, and mortality in critical illness and on the potential risks of therapy.

CONCLUSIONS

Fe deficiency anemia and the anemia of inflammation may co-exist in critical illness. Diagnosis of and differentiation between these two anemias involves careful interpretation of multiple markers of total body Fe stores. The utility of treatment with both Fe and recombinant human erythropoietin for these disorders during critical illness requires further investigation.