Tissue Iron Distribution in Anemic Patients with End-Stage Kidney Disease: Results of a Pilot Study

Background/Objectives: Anemia is a frequent multifactorial co-morbidity in end-stage kidney disease (ESKD) associated with morbidity and poor QoL. Apart from insufficient erythropoietin formation, iron deficiency (ID) contributes to anemia development. Identifying patients in need of iron supplementation with current ID definitions is difficult since no good biomarker is available to detect actual iron needs. Therefore, new diagnostic tools to guide therapy are needed. Methods: We performed a prospective cohort study analyzing tissue iron content with MRI-based R2*-relaxometry in 20 anemic ESKD patients and linked it with iron biomarkers in comparison to 20 otherwise healthy individuals. Results: ESKD patients had significantly higher liver (90.1 s-1 vs. 36.1 s-1, p < 0.001) and spleen R2* values (119.8 s-1 vs. 19.3 s-1, p < 0.001) compared to otherwise healthy individuals, while their pancreas and heart R2* values did not significantly differ. Out of the 20 ESKD patients, 17 had elevated spleen and 12 had elevated liver R2* values. KDIGO guidelines (focusing on serum iron parameters) would recommend iron supplementation in seven patients with elevated spleen and four patients with elevated liver R2* values. Conclusions: These findings highlight that liver and especially spleen iron concentrations are significantly higher in ESKD patients compared to controls. Tissue iron overload diverged from classical iron parameters suggesting need of iron supplementation. Measurement of MRI-guided tissue iron distribution might help guide treatment of anemic ESKD patients.

Understanding How Minerals Contribute to Optimal Immune Function

Sufficient mineral supply is vital not only for the innate immune system but also for the components of the adaptive immune defense, which encompass defense mechanisms against pathogens and the delicate balance of pro- and anti-inflammatory regulation in the long term. Generally, a well-balanced diet is capable of providing the necessary minerals to support the immune system. Nevertheless, specific vulnerable populations should be cautious about obtaining adequate amounts of minerals such as magnesium, zinc, copper, iron, and selenium. Inadequate levels of these minerals can temporarily impair immune competence and disrupt the long-term regulation of systemic inflammation. Therefore, comprehending the mechanisms and sources of these minerals is crucial. In exceptional circumstances, mineral deficiencies may necessitate supplementation; however, excessive intake of supplements can have adverse effects on the immune system and should be avoided. Consequently, any supplementation should be approved by medical professionals and administered in recommended doses. This review emphasizes the crucial significance of minerals in promoting optimal functioning of the immune system. It investigates the indispensable minerals required for immune system function and the regulation of inflammation. Moreover, it delves into the significance of maintaining an optimized intake of minerals from a nutritional standpoint.

Comparative analysis of oral and intravenous iron therapy in rat models of inflammatory anemia and iron deficiency

Anemia is a major health issue and associated with increased morbidity. Iron deficiency anemia (IDA) is the most prevalent, followed by anemia of chronic disease (ACD). IDA and ACD often co-exist, challenging diagnosis and treatment. While iron supplementation is the first-line therapy for IDA, its optimal route of administration and the efficacy of different repletion strategies in ACD are elusive. Female Lewis rats were injected with group A streptococcal peptidoglycan-polysaccharide (PG-APS) to induce inflammatory arthritis with associated ACD and/or repeatedly phlebotomized and fed with a low iron diet to induce IDA, or a combination thereof (ACD/IDA). Iron was either supplemented by daily oral gavage of ferric maltol or by weekly intravenous (i.v.) injection of ferric carboxymaltose for up to 4 weeks. While both strategies reversed IDA, they remained ineffective to improve hemoglobin (Hb) levels in ACD, although oral iron showed slight amelioration of various erythropoiesis-associated parameters. In contrast, both iron treatments significantly increased Hb in ACD/IDA. In ACD and ACD/IDA animals, i.v. iron administration resulted in iron trapping in liver and splenic macrophages, induction of ferritin expression and increased circulating levels of the iron hormone hepcidin and the inflammatory cytokine interleukin-6, while oral iron supplementation reduced interleukin-6 levels. Thus, oral and i.v. iron resulted in divergent effects on systemic and tissue iron homeostasis and inflammation. Our results indicate that both iron supplements improve Hb in ACD/IDA, but are ineffective in ACD with pronounced inflammation, and that under the latter condition, i.v. iron is trapped in macrophages and may enhance inflammation.

Erythropoiesis-independent effects of iron in chronic kidney disease

Chronic kidney disease (CKD) leads to alterations of iron metabolism, which contribute to the development of anemia and necessitates iron supplementation in patients with CKD. Elevated hepcidin accounts for a significant iron redistribution in CKD. Recent data indicate that these alterations in iron homeostasis coupled with therapeutic iron supplementation have pleiotropic effects on many organ systems in patients with CKD, far beyond the traditional hematologic effects of iron; these include effects of iron on inflammation, oxidative stress, kidney fibrosis, cardiovascular disease, CKD-mineral and bone disorder, and skeletal growth in children. The effects of iron supplementation appear to be largely dependent on the route of administration and on the specific iron preparation. Iron-based phosphate binders exemplify the opportunity for using iron for both traditional (anemia) and novel (hyperphosphatemia) indications. Further optimization of iron therapy in patients with CKD may inform new approaches to the treatment of CKD complications and potentially allow modification of disease progression.

Quantity of IgG response to SARS-CoV-2 spike glycoprotein predicts pulmonary recovery from COVID-19

The CovILD study is a prospective, multicenter, observational cohort study to systematically follow up patients after coronavirus disease-2019 (COVID-19). We extensively evaluated 145 COVID-19 patients at 3 follow-up visits scheduled for 60, 100, and 180 days after initial confirmed diagnosis based on typical symptoms and a positive reverse transcription-polymerase chain reaction (RT-PCR) for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). We employed comprehensive pulmonary function and laboratory tests, including serum concentrations of IgG against the viral spike (S) glycoprotein, and compared the results to clinical data and chest computed tomography (CT). We found that at the 60 day follow-up, 131 of 145 (90.3%) participants displayed S-specific serum IgG levels above the cut-off threshold. Notably, the highly elevated IgG levels against S glycoprotein positively correlated with biomarkers of immune activation and negatively correlated with pulmonary function and the extent of pulmonary CT abnormalities. Based on the association between serum S glycoprotein-specific IgG and clinical outcome, we generated an S-specific IgG-based recovery score that, when applied in the early convalescent phase, accurately predicted delayed pulmonary recovery after COVID-19. Therefore, we propose that S-specific IgG levels serve as a useful immunological surrogate marker for identifying at-risk individuals with persistent pulmonary injury who may require intensive follow-up care after COVID-19.

Saccharated ferric oxide attenuates haematopoietic response induced by epoetin beta pegol in patients undergoing haemodialysis

Background

Decreased erythropoietin levels and impaired iron metabolism due to excessive hepcidin levels are responsible for renal anaemia in patients undergoing haemodialysis. Recently, erythroferrone (ERFE) has been identified as a factor that regulates hepcidin. In addition, fibroblast growth factor 23 (FGF23), which has been recognized as a phosphorus-regulating hormone, appears to be involved in haematopoietic regulation. Clarification of the detailed mechanism of haematopoiesis could lead to the improvement of renal anaemia treatment.

Methods

Epoetin beta pegol (CERA) was administered to patients undergoing haemodialysis at week 0, and the same amount of CERA with saccharated ferric oxide (SFO) was administered at week 4. The changes in haematopoiesis-related biomarkers, including ERFE, intact FGF23 (iFGF23), C-terminal FGF23 (cFGF23), and inflammatory markers, were examined.

Results

Administration of CERA increased ERFE levels, decreased hepcidin levels, and stimulated iron usage for haematopoiesis, leading to an increase in reticulocytes (Ret) and haemoglobin (Hb). Simultaneous administration of SFO with CERA (CERA + SFO) significantly attenuated the responses of ERFE, Ret, and Hb compared with CERA alone. Although iFGF23 levels were not affected by either CERA or CERA + SFO, cFGF23 was significantly elevated from baseline after CERA. Since cFGF23 levels were not affected by CERA + SFO, cFGF23 levels after CERA + SFO were significantly lower than those after CERA alone. The ratio of iFGF23 to cFGF23 (i/cFGF23 ratio) was significantly higher after CERA + SFO than that after CERA alone. In addition, high-sensitivity C-reactive protein (hsCRP) levels were significantly higher after CERA + SFO than after CERA alone.

Conclusion

Administration of SFO suppressed haematopoietic responses induced by CERA. Elevation of i/cFGF23 ratio and hsCRP could account for the inhibitory effects of SFO on haematopoiesis.

Trial registration

This study was registered with the University Hospital Medical Information Network (ID UMIN000016552).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02320-2.

TAM-ing the CIA-Tumor-Associated Macrophages and Their Potential Role in Unintended Side Effects of Therapeutics for Cancer-Induced Anemia

Cancer-induced anemia (CIA) is a common consequence of neoplasia and has a multifactorial pathophysiology. The immune response and tumor treatment, both intended to primarily target malignant cells, also affect erythropoiesis in the bone marrow. In parallel, immune activation inevitably induces the iron-regulatory hormone hepcidin to direct iron fluxes away from erythroid progenitors and into compartments of the mononuclear phagocyte system. Moreover, many inflammatory mediators inhibit the synthesis of erythropoietin, which is essential for stimulation and differentiation of erythroid progenitor cells to mature cells ready for release into the blood stream. These pathophysiological hallmarks of CIA imply that the bone marrow is not only deprived of iron as nutrient but also of erythropoietin as central growth factor for erythropoiesis. Tumor-associated macrophages (TAM) are present in the tumor microenvironment and display altered immune and iron phenotypes. On the one hand, their functions are altered by adjacent tumor cells so that they promote rather than inhibit the growth of malignant cells. As consequences, TAM may deliver iron to tumor cells and produce reduced amounts of cytotoxic mediators. Furthermore, their ability to stimulate adaptive anti-tumor immune responses is severely compromised. On the other hand, TAM are potential off-targets of therapeutic interventions against CIA. Red blood cell transfusions, intravenous iron preparations, erythropoiesis-stimulating agents and novel treatment options for CIA may interfere with TAM function and thus exhibit secondary effects on the underlying malignancy. In this Hypothesis and Theory, we summarize the pathophysiological hallmarks, clinical implications and treatment strategies for CIA. Focusing on TAM, we speculate on the potential intended and unintended effects that therapeutic options for CIA may have on the innate immune response and, consequently, on the course of the underlying malignancy.

Persisting alterations of iron homeostasis in COVID-19 are associated with non-resolving lung pathologies and poor patients' performance: a prospective observational cohort study

BACKGROUND

Severe coronavirus disease 2019 (COVID-19) is frequently associated with hyperinflammation and hyperferritinemia. The latter is related to increased mortality in COVID-19. Still, it is not clear if iron dysmetabolism is mechanistically linked to COVID-19 pathobiology.

METHODS

We herein present data from the ongoing prospective, multicentre, observational CovILD cohort study (ClinicalTrials.gov number, NCT04416100), which systematically follows up patients after COVID-19. 109 participants were evaluated 60 days after onset of first COVID-19 symptoms including clinical examination, chest computed tomography and laboratory testing.

RESULTS

We investigated subjects with mild to critical COVID-19, of which the majority received hospital treatment. 60 days after disease onset, 30% of subjects still presented with iron deficiency and 9% had anemia, mostly categorized as anemia of inflammation. Anemic patients had increased levels of inflammation markers such as interleukin-6 and C-reactive protein and survived a more severe course of COVID-19. Hyperferritinemia was still present in 38% of all individuals and was more frequent in subjects with preceding severe or critical COVID-19. Analysis of the mRNA expression of peripheral blood mononuclear cells demonstrated a correlation of increased ferritin and cytokine mRNA expression in these patients. Finally, persisting hyperferritinemia was significantly associated with severe lung pathologies in computed tomography scans and a decreased performance status as compared to patients without hyperferritinemia.

DISCUSSION

Alterations of iron homeostasis can persist for at least two months after the onset of COVID-19 and are closely associated with non-resolving lung pathologies and impaired physical performance. Determination of serum iron parameters may thus be a easy to access measure to monitor the resolution of COVID-19.

TRIAL REGISTRATION

ClinicalTrials.gov number: NCT04416100.

Effect of HFE Gene Mutation on Changes in Iron Metabolism Induced by Nordic Walking in Elderly Women

Background

Excess iron accumulation in human tissue is associated with the diet, lack of exercise, or genetic factors. Iron accumulation increases the risk of acute myocardial infarction, diabetes, and cancer. On the other hand, exercise reduces the risk of several morbidities and influences iron metabolism. Here, we evaluated changes in iron metabolism induced by exercise in elderly women bearing the H63A HFE mutation.

Purpose

To identify a factor that modulates the effect of exercise on iron metabolism. We investigated whether regular exercise induces similar changes in iron metabolism, mainly manifested by lowered body iron stores, in individuals bearing the wild-type (WT) and mutated HFE gene.

Subjects and Methods

Seventy-six women (average age 69.2±5.6 years old) were enrolled in the study. Thirty-nine women participated in 12 weeks of Nordic walking (NW) training; the remaining participants were assigned to the control group. Based on the H63A HFE mutation status, the NW group was divided into women bearing the mutation (HET, n=12) and women with the WT gene (WT, n=27).

Results

The training resulted in a statistically significant reduction in the serum iron (p=0.03) and ferritin levels (p=0.001); hepcidin levels remained unchanged. No differences in these parameters were noted between the HET and WT groups.

Conclusion

These observations suggest that a reduction in body iron stores might constitute an important aspect of the health-promoting effect of exercise, regardless of the genetic background.

Anaemia, iron homeostasis and pulmonary hypertension: a review

Anaemia is a highly prevalent condition, which negatively impacts on patients' cardiovascular performance and quality of life. Anaemia is mainly caused by disturbances of iron homeostasis. While absolute iron deficiency mostly as a consequence of chronic blood loss or insufficient dietary iron absorption results in the emergence of iron deficiency anaemia, inflammation-driven iron retention in innate immune cells and blockade of iron absorption leads to the development of anaemia of chronic disease. Both, iron deficiency and anaemia have been linked to the clinical course of pulmonary hypertension. Various mechanistic links between iron homeostasis, anaemia, and pulmonary hypertension have been described and current treatment guidelines suggest regular iron status assessment and the implementation of iron supplementation strategies in these patients. The pathophysiology, diagnostic assessment as well as current and future treatment options concerning iron deficiency with or without anaemia in individuals suffering from pulmonary hypertension are discussed within this review.

Monocytes in Uremia

Monocytes play an important role in both innate immunity and antigen presentation for specific cellular immune defense. In patients with chronic renal failure, as well as those treated with maintenance hemodialysis, these cells are largely dysregulated. There is a large body of literature on monocyte alterations in such patients. However, most of the publications report on small series, there is a vast spectrum of different methods and the heterogeneity of the data prevents any meta-analytic approach. Thus, a narrative review was performed to describe the current knowledge. Monocytes from patients with chronic renal failure differ from those of healthy individuals in the pattern of surface molecule expression, cytokine and mediator production, and function. If these findings can be summarized at all, they might be subsumed as showing chronic inflammation in resting cells together with limited activation upon immunologic challenge. The picture is complicated by the fact that monocytes fall into morphologically and functionally different populations and population shifts interact heavily with dysregulation of the individual cells. Severe complications of chronic renal failure such as impaired immune defense, inflammation, and atherosclerosis can be related to several aspects of monocyte dysfunction. Therefore, this review aims to provide an overview about the impairment and activation of monocytes by uremia and the resulting clinical consequences for renal failure patients.

Intravenous ferric carboxymaltose for iron deficiency anemia in dialysis patients: Effect of a new protocol adopted for a hemodialysis limited assistance center

Iron and erythropoietin deficiencies are determinants of anemia in chronic kidney disease. In hemodialysis (HD) patients, intravenous (IV) iron is associated with a greater hemoglobin (Hb) production and better erythropoietin response but may be associated to hypersensitivity reaction. After the 2013 European Medicines Agency report regarding early detection/management of iron allergic reactions, IV iron administration dramatically reduced in Italian Hemodialysis-Limited-Assistance-Centre (HD-CAL) where a physician is present only once a week. Objective of the study was providing an effective and secure IV iron administration protocol for HD-CAL patients. IV ferric carboxymaltose (FCM) administration was more effective and better tolerated than sodium ferric gluconate for iron deficiency correction and resolution of anemia in 24 patients undergoing HD in our HD-CAL. Six months of FCM IV treatment once a week increased ferritin and Hb compared to sodium ferric gluconate once a week leading to decreased erythropoietin consumption from 24 000 to 15 000 U/patient/week with an erythropoietin annual expense reduction. No blood transfusions, gastrointestinal intolerance or other adverse effects were reported. The FCM IV administration protocol for our HD-CAL patients was safe and no adverse events were reported, resulting in significantly increased ferritin, transferrin saturation, and Hb levels, reduction of erythropoietin requirements, and consequently reduction of erythropoietin expenses.

Anemia and iron deficiency in Crohn's disease

Introduction: Anemia is a common extraintestinal complication of Crohn's disease (CD) mainly caused by iron deficiency, that affects the quality of life in CD patients. Elucidation of the etiology and pathology of iron-deficiency anemia (IDA) and anemia of chronic diseases (ACD) has developed in recent years. Common biochemical parameters of iron status are insufficient for assessment of patients with anemia and CD. Thus, novel iron indices are required for accurate assessment in IDA patients with CD. Oral iron supplementation for IDA treatment is common and is associated with minor gastrointestinal side effects. Intravenous substitution improves safety profiles but may be not tolerable in some patients. Fortunately, additional therapies for anemia of active CD have emerged in recent years.Area covered: Here, we propose the review article on the link among anemia, iron deficiency, and Crohn's disease. We discuss the current diagnosis and therapy of anemia and iron deficiency in CD and propose the new directions for future research.Expert commentary: Exploring pathogeneses and treatments of anemia and iron deficiency in Crohn's disease will develop potential tools for early diagnosis and effective treatment of anemia in CD patients, and improve their life quality.

Metalloimmunology: The metal ion-controlled immunity

Metals are essential components in all forms of life required for the function of nearly half of all enzymes and are critically involved in virtually all fundamental biological processes. Especially, the transition metals iron (Fe), zinc (Zn), manganese (Mn), nickel (Ni), copper (Cu) and cobalt (Co) are crucial micronutrients known to play vital roles in metabolism as well due to their unique redox properties. Metals carry out three major functions within metalloproteins: to provide structural support, to serve as enzymatic cofactors, and to mediate electron transportation. Metal ions are also involved in the immune system from metal allergies to nutritional immunity. Within the past decade, much attention has been drawn to the roles of metal ions in the immune system, since increasing evidence has mounted to suggest that metals are critically implicated in regulating both the innate immune sensing of and the host defense against invading pathogens. The importance of ions in immunity is also evidenced by the identification of various immunodeficiencies in patients with mutations in ion channels and transporters. In addition, cancer immunotherapy has recently been conclusively demonstrated to be effective and important for future tumor treatment, although only a small percentage of cancer patients respond to immunotherapy because of inadequate immune activation. Importantly, metal ion-activated immunotherapy is becoming an effective and potential way in tumor therapy for better clinical application. Nevertheless, we are still in a primary stage of discovering the diverse immunological functions of ions and mechanistically understanding the roles of these ions in immune regulation. This review summarizes recent advances in the understanding of metal-controlled immunity. Particular emphasis is put on the mechanisms of innate immune stimulation and T cell activation by the essential metal ions like calcium (Ca²⁺), zinc (Zn²⁺), manganese (Mn²⁺), iron (Fe²⁺/Fe³⁺), and potassium (K⁺), followed by a few unessential metals, in order to draw a general diagram of metalloimmunology.

Tumour necrosis factor-alpha in uraemic serum promotes osteoblastic transition and calcification of vascular smooth muscle cells via extracellular signal-regulated kinases and activator protein 1/c-FOS-mediated induction of interleukin 6 expression

Background

Vascular calcification is enhanced in uraemic chronic haemodialysis patients, likely due to the accumulation of midsize uraemic toxins, such as interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF-α). Here we have assessed the impact of uraemia on vascular smooth muscle cell (VSMC) calcification and examined the role of IL-6 and TNF-α as possible mediators and, most importantly, its underlying signalling pathway in VSMCs.

Methods

VSMCs were incubated with samples of uraemic serum obtained from patients treated with haemodialysis for renal failure in the Permeability Enhancement to Reduce Chronic Inflammation-I clinical trial. The VSMCs were assessed for IL-6 gene regulation and promoter activation in response to uraemic serum and TNF-α with reporter assays and electrophoretic mobility shift assay and for osteoblastic transition, cellular calcification and cell viability upon osteogenic differentiation.

Results

Uraemic serum contained higher levels of TNF-α and IL-6 compared with serum from healthy individuals. Exposure of VSMCs to uraemic serum or recombinant TNF-α lead to a strong upregulation of IL-6 mRNA expression and protein secretion, which was mediated by activator protein 1 (AP-1)/c-FOS-pathway signalling. Uraemic serum induced osteoblastic transition and calcification of VSMCs could be strongly attenuated by blocking TNF-α, IL-6 or AP-1/c-FOS signalling, which was accompanied by improved cell viability.

Conclusion

These results demonstrate that uraemic serum contains higher levels of uraemic toxins TNF-α and IL-6 and that uraemia promotes vascular calcification through a signalling pathway involving TNF-α, IL-6 and the AP-1/c-FOS cytokine-signalling axis. Thus treatment modalities aiming to reduce systemic TNF-α and IL-6 levels in chronic haemodialysis patients should be evaluated in future clinical trials.

Hepcidin as a potential predictor for preoperative anemia treatment with intravenous iron-A retrospective pilot study

Preoperative anemia occurs in about one third of patients who undergo elective surgery and is associated with an impaired outcome. Therefore, screening of preoperative anemia was established in the context of a multidisciplinary Patient Blood Management (PBM) program at the University Hospital of Muenster, Germany. Anemic patients without contraindications were treated with intravenous (IV) iron (ferric carboxymaltose) to increase their hemoglobin (Hgb) levels and hence to treat anemia prior to surgery. Interestingly, we detected a large variability in the response of Hgb levels after IV iron administration. Systemic iron homeostasis is mainly regulated by the hepatic hormone hepcidin, which regulates the cell surface expression of the sole known iron exporter ferroportin. The objective of this retrospective pilot study was to analyze the potential of hepcidin to predict the response of anemic patients to preoperative IV iron treatment measured as increase in Hgb.

Serum samples of non-anemic (n = 48), untreated anemic (n = 64) and anemic patients treated with IV iron (n = 79), in total 191 patients, were collected between October 2014 until June 2016. Serum hepcidin levels were determined and data were analyzed retrospectively.

The analysis revealed at first a correlation between serum hepcidin levels and the parameters of the iron status. Second, patients treated with IV iron showed a noticeably higher increase in their delta Hgb level between PBM consultation and surgery (0.45g/dl [0.05, 1.05] compared to patients without IV iron (0.1g/dl [-0.48, 0.73], *p = 0.03). Patients were then grouped into ‘non-responders’, defined as delta Hgb <0.6g/dl and ‘responders’, with delta Hgb ≥0.6g/dl between the day of IV iron treatment and the day of surgery. Within normal ranges and clinically unapparent, a statistically noticeable difference between responders and non-responders was found for CRP and leukocytes. Serum hepcidin levels were higher in the group of non-responders (10.6ng/ml [3.93, 34.77]) compared to responders (2.1ng/ml [0.25, 7.97], *p = 0.04).

To conclude, the data of this retrospective pilot study indicate that hepcidin might be a promising biomarker to predict a patient`s responsiveness to IV iron in preoperative anemia treatment. Prospective studies have to investigate serum hepcidin levels as a biomarker to guide physician`s decision on IV iron substitution.

Iron and innate antimicrobial immunity-Depriving the pathogen, defending the host

The acute-phase response is triggered by the presence of infectious agents and danger signals which indicate hazards for the integrity of the mammalian body. One central feature of this response is the sequestration of iron into storage compartments including macrophages. This limits the availability of this essential nutrient for circulating pathogens, a host defence strategy known as 'nutritional immunity'. Iron metabolism and the immune response are intimately linked. In infections, the availability of iron affects both the efficacy of antimicrobial immune pathways and pathogen proliferation. However, host strategies to withhold iron from microbes vary according to the localization of pathogens: Infections with extracellular bacteria such as Staphylococcus aureus, Streptococcus, Klebsiella or Yersinia stimulate the expression of the iron-regulatory hormone hepcidin which targets the cellular iron-exporter ferroportin-1 causing its internalization and blockade of iron egress from absorptive enterocytes in the duodenum and iron-recycling macrophages. This mechanism disrupts both routes of iron delivery to the circulation, contributes to iron sequestration in the mononuclear phagocyte system and mediates the hypoferraemia of the acute phase response subsequently resulting in the development of anaemia of inflammation. When intracellular microbes are present, other strategies of microbial iron withdrawal are needed. For instance, in macrophages harbouring intracellular pathogens such as Chlamydia, Mycobacterium tuberculosis, Listeria monocytogenes or Salmonella Typhimurium, ferroportin-1-mediated iron export is turned on for the removal of iron from infected cells. This also leads to reduced iron availability for intra-macrophage pathogens which inhibits their growth and in parallel strengthens anti-microbial effector pathways of macrophages including the formation of inducible nitric oxide synthase and tumour necrosis factor. Iron plays a key role in infectious diseases both as modulator of the innate immune response and as nutrient for microbes. We need to gain a more comprehensive understanding of how the body can differentially respond to infection by extra- or intracellular pathogens. This knowledge may allow us to modulate mammalian iron homeostasis pharmaceutically and to target iron-acquisition systems of pathogens, thus enabling us to treat infections with novel strategies that act independent of established antimicrobials.

Serum iron level and kidney function: a Mendelian randomization study

Background

Iron depletion is a known consequence of chronic kidney disease (CKD), but there is contradicting epidemiological evidence on whether iron itself affects kidney function and whether its effect is protective or detrimental in the general population. While epidemiological studies tend to be affected by confounding and reverse causation, Mendelian randomization (MR) can provide unconfounded estimates of causal effects by using genes as instruments.

Methods

We performed an MR study of the effect of serum iron levels on estimated glomerular filtration rate (eGFR), using genetic variants known to be associated with iron. MR estimates of the effect of iron on eGFR were derived based on the association of each variant with iron and eGFR from two large genome-wide meta-analyses on 48 978 and 74 354 individuals. We performed a similar MR analysis for ferritin, which measures iron stored in the body, using variants associated with ferritin.

Results

A combined MR estimate across all variants showed a 1.3% increase in eGFR per standard deviation increase in iron (95% confidence interval 0.4–2.1%; P = 0.004). The results for ferritin were consistent with those for iron. Secondary MR analyses of the effects of iron and ferritin on CKD did not show significant associations but had very low statistical power.

Conclusions

Our study suggests a protective effect of iron on kidney function in the general population. Further research is required to confirm this causal association, investigate it in study populations at higher risk of CKD and explore its underlying mechanism of action.

Safety of Intravenous Iron in Dialysis: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

The safety of intravenous iron dosing in dialysis is uncertain. Higher-dose intravenous iron may be associated with a higher risk of infections, cardiovascular events, hospitalizations, and mortality. This systematic review aimed to determine the safety of higher-dose versus lower-dose intravenous iron, oral iron, or no iron supplementation in adult patients treated with dialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We searched Medline, EMBASE, Cochrane library, and CINAHL from inception to January 6, 2017 for randomized, controlled trials and observational studies comparing higher-dose intravenous iron with lower-dose intravenous iron, oral iron, or no iron in patients treated with dialysis that had all-cause mortality, infection, cardiovascular events, or hospitalizations as outcomes.

RESULTS

Of the 2231 eligible studies, seven randomized, controlled trials and 15 observational studies met inclusion criteria. The randomized, controlled trials showed no association between higher-dose intravenous iron (>400 mg/mo for most studies) and mortality (six studies; n=970; pooled relative risk, 0.93; 95% confidence interval, 0.47 to 1.84; follow-up ranging from 35 days to 26 months) or infection (four studies; n=743; relative risk, 1.02; 95% confidence interval, 0.74 to 1.41). The observational studies showed no association between higher-dose intravenous iron (>200 mg/mo for most studies) and mortality (eight studies; n=241,408; hazard ratio, 1.09; 95% confidence interval, 0.98 to 1.21; follow-up ranging from 3 to 24 months), infection (eight studies; n=135,532; pooled hazard ratio, 1.13; 95% confidence interval, 0.99 to 1.28), cardiovascular events (seven studies; n=135,675; hazard ratio, 1.18; 95% confidence interval, 0.90 to 1.56), or hospitalizations (five studies; n=134,324; hazard ratio, 1.08; 95% confidence interval, 0.97 to 1.19).

CONCLUSIONS

Higher-dose intravenous iron does not seem to be associated with higher risk of mortality, infection, cardiovascular events, or hospitalizations in adult patients on dialysis. Strength of this finding is limited by small numbers of participants and events in the randomized, controlled trials and statistical heterogeneity in observational studies.

Rational Management of Iron-Deficiency Anaemia in Inflammatory Bowel Disease

Anaemia is the most frequent, though often neglected, comorbidity of inflammatory bowel disease (IBD). Here we want to briefly present (1) the burden of anaemia in IBD, (2) its pathophysiology, which mostly arises from bleeding-associated iron deficiency, followed by (3) diagnostic evaluation of anaemia, (4) a balanced overview of the different modes of iron replacement therapy, (5) evidence for their therapeutic efficacy and subsequently, (6) an updated recommendation for the practical management of anaemia in IBD. Following the introduction of various intravenous iron preparations over the last decade, questions persist about when to use these preparations as opposed to traditional and other novel oral iron therapeutic agents. At present, oral iron therapy is generally preferred for patients with quiescent IBD and mild iron-deficiency anaemia. However, in patients with flaring IBD that hampers intestinal iron absorption and in those with inadequate responses to or side effects with oral preparations, intravenous iron supplementation is the therapy of choice, although information on the efficacy of intravenous iron in patients with active IBD and anaemia is scare. Importantly, anaemia in IBD is often multifactorial and a careful diagnostic workup is mandatory for optimized treatment. Nevertheless, limited information is available on optimal therapeutic start and end points for treatment of anaemia. Of note, neither oral nor intravenous therapies seem to exacerbate the clinical course of IBD. However, additional prospective studies are still warranted to determine the optimal therapy in complex conditions such as IBD.

Serum Iron Protects from Renal Postischemic Injury

Renal transplants remain a medical challenge, because the parameters governing allograft outcome are incompletely identified. Here, we investigated the role of serum iron in the sterile inflammation that follows kidney ischemia-reperfusion injury. In a retrospective cohort study of renal allograft recipients (n=169), increased baseline levels of serum ferritin reliably predicted a positive outcome for allografts, particularly in elderly patients. In mice, systemic iron overload protected against renal ischemia-reperfusion injury-associated sterile inflammation. Furthermore, chronic iron injection in mice prevented macrophage recruitment after inflammatory stimuli. Macrophages cultured in high-iron conditions had reduced responses to Toll-like receptor-2, -3, and -4 agonists, which associated with decreased reactive oxygen species production, increased nuclear localization of the NRF2 transcription factor, increased expression of the NRF2-related antioxidant response genes, and limited NF-κB and proinflammatory signaling. In macrophage-depleted animals, the infusion of macrophages cultured in high-iron conditions did not reconstitute AKI after ischemia-reperfusion, whereas macrophages cultured in physiologic iron conditions did. These findings identify serum iron as a critical protective factor in renal allograft outcome. Increasing serum iron levels in patients may thus improve prognosis of renal transplants.

A single dialysis session of hemodiafiltration with sorbent-regenerated endogenous ultrafiltrate reinfusion (HFR) removes hepcidin more efficiently than bicarbonate hemodialysis: a new approach to containing hepcidin burden in dialysis patients?

BACKGROUND

Most hemodialysis patients have high Hepcidin-25 levels, which may be involved in the pathogenesis of several uremic complications related to an altered iron biology. The hemodialysis procedure itself can influence Hepcidin-25 levels by removing Hepcidin-25 and maybe stimulating its production due to a pro-inflammatory effect.

METHODS

To assess the relationship between dialysis-related inflammation and intradialysis changes in Hepcidin-25, we performed a crossover trial in 28 hemodialysis patients to compare the effects on serum levels of Hepcidin-25 and inflammatory markers activated during dialysis [Tumor Necrosis Factor-α (TNF-α), Interleukin-6, C-reactive protein (CRP), Pentraxin-3] of a single dialysis session using a technique capable of reducing inflammation, HFR (Hemo Filtrate Reinfusion: a hemodiafiltration system combining convection, diffusion and adsorption) or bicarbonate-dialysis using either the same low-flux membrane as in the diffusion stage of HFR (LFBD) or a high-flux membrane (HFBD).

RESULTS

HFR achieved a greater reduction in Hepcidin-25 levels than both LFBD [-72% (95% CI: -11 to -133), p = 0.022] and HFBD [-137% (95% CI: -2 to -272), p = 0.047], conceivably due to both a greater removal (because of its convective/adsorptive component) and a lower inflammation-related Hepcidin-25 production. HFR also led to a greater decrease in TNF-α than LFBD [-277% (95% CI: -59 to -494), p = 0.014], while the two methods induced similar changes in Interleukin-6, CRP and Pentraxin-3 levels.

CONCLUSIONS

Our findings suggest that a single bicarbonate-dialysis session can upregulate Hepcidin-25 synthesis and that HFR can fully overcome this effect, enabling a greater Hepcidin-25 removal during dialysis. Adequately-designed studies are needed, however, to establish whether the beneficial effect of HFR emerging from our study could reduce Hepcidin-25 (and TNF-α) burden and improve clinically-relevant outcomes.

TRIAL REGISTRATION

ISRCTN15957905.

High Ferritin Level and Malnutrition Predict High Risk of Infection-Related Hospitalization in Incident Dialysis Patients: A Japanese Prospective Cohort Study

AIMS

The aim of the study was to clarify the relationship between serum ferritin and infectious risks.

METHODS

We evaluated all hospital admissions due to infections, clinical biomarkers and nutrition status in 129 incident Japanese dialysis patients during a median follow-up of 38 months.

RESULTS

Kaplan-Meier analysis revealed that the period without infections requiring hospitalization was significantly shorter in ferritin > median (82.0 ng/ml) group than in the ferritin < median group (log-rank test 4.44, p = 0.035). High ferritin was associated with significantly increased relative risk of hospitalization for infection (Cox hazard model 1.52, 95% CI 1.06-2.17). The number of hospitalization days was gradually longer in patients with high ferritin levels and malnutrition.

CONCLUSION

Although serum ferritin levels were low, and doses of iron administered to dialysis patients in Japan are generally lower than in Western countries, an elevated ferritin level was associated with increased risk of infection, particularly in patients with poor nutritional status.

Iron replacement therapy: do we need new guidelines?

PURPOSE OF REVIEW

Approximately, one-third of the world's population suffers from anemia, and at least half of these cases are because of iron deficiency. With the introduction of new intravenous iron preparations over the last decade, uncertainty has arisen when these compounds should be administered and under which circumstances oral therapy is still an appropriate and effective treatment.

RECENT FINDINGS

Numerous guidelines are available, but none go into detail about therapeutic start and end points or how iron-deficiency anemia should be best treated depending on the underlying cause of iron deficiency or in regard to concomitant underlying or additional diseases.

SUMMARY

The study points to major issues to be considered in revisions of future guidelines for the true optimal iron replacement therapy, including how to assess the need for treatment, when to start and when to stop treatment, when to follow-up for relapse, which dosage and type of therapy should be recommended or not recommended, and if some patients should not be treated.

Iron supplementation and mortality in incident dialysis patients: an observational study

BACKGROUND

Studies on the association between iron supplementation and mortality in dialysis patients are rare and conflicting.

METHODS

In our observational single-center cohort study (INVOR study) we prospectively studied 235 incident dialysis patients. Time-dependent Cox proportional hazards models using all measured laboratory values for up to 7.6 years were applied to study the association between iron supplementation and all-cause mortality, cardiovascular and sepsis-related mortality. Furthermore, the time-dependent association of ferritin levels with mortality in patients with normal C-reactive protein (CRP) levels (<0.5 mg/dL) and elevated CRP levels (≧0.5 mg/dL) was evaluated by using non-linear P-splines to allow flexible modeling of the association.

RESULTS

One hundred and ninety-one (81.3%) patients received intravenous iron, 13 (5.5%) patients oral iron, whereas 31 (13.2%) patients were never supplemented with iron throughout the observation period. Eighty-two (35%) patients died during a median follow-up of 34 months, 38 patients due to cardiovascular events and 21 patients from sepsis. Baseline CRP levels were not different between patients with and without iron supplementation. However, baseline serum ferritin levels were lower in patients receiving iron during follow up (median 93 vs 251 ng/mL, p<0.001). Iron supplementation was associated with a significantly reduced all-cause mortality [HR (95%CI): 0.22 (0.08-0.58); p = 0.002] and a reduced cardiovascular and sepsis-related mortality [HR (95%CI): 0.31 (0.09-1.04); p = 0.06]. Increasing ferritin concentrations in patients with normal CRP were associated with a decreasing mortality, whereas in patients with elevated CRP values ferritin levels>800 ng/mL were linked with increased mortality.

CONCLUSIONS

Iron supplementation is associated with reduced all-cause mortality in incident dialysis patients. While serum ferritin levels up to 800 ng/mL appear to be safe, higher ferritin levels are associated with increased mortality in the setting of concomitant inflammation.

Iron sucrose and ferric carboxymaltose: no correlation between physicochemical stability and biological activity

Intravenous iron preparations, like iron sucrose (IS) and ferric carboxymaltose (FCM) differ in their physicochemical stability. Thus differences in storage and utilization can be expected and were investigated in a non-clinical study in liver parenchyma HepG2-cells and THP-1 macrophages as models for toxicological and pharmacological target cells. HepG2-cells incorporated significant amounts of IS, elevated the labile iron pool (LIP) and ferritin and stimulated iron release. HepG2-cells had lower basal cellular iron and ferritin content than THP-1 macrophages, which showed only marginal accumulation of IS and FCM. However, FCM increased the LIP up to twofold and significantly elevated ferritin within 24 h in HepG2-cells. IS and FCM were non-toxic for HepG2-cells and THP-1 macrophages were more sensitive to FCM compared to IS at all concentrations tested. In a cell-free environment redox-active iron was higher with IS than FCM. Biostability testing via assessment of direct transfer to serum transferrin did not reflect the chemical stability of the complexes (i.e., FCM > IS). Effect of vitamin C on mobilisation to transferrin was an increase with IS and interestingly a decrease with FCM. In conclusion, FCM has low bioavailability for liver parenchyma cells, therefore liver iron deposition is unlikely. Ascorbic acid reduces transferrin-chelatable iron from ferric carboxymaltose, thus effects on hepcidin expression should be investigated in clinical studies.

Distinct immunologic effects of different intravenous iron preparations on monocytes

Background

Iron deficiency contributes to anaemia in patients with chronic kidney disease. I.v. iron is therefore widely used for anaemia treatment, although it may induce oxidative stress and activate monocytes. Different i.v. iron preparations are available, but interestingly their substance-specific immunologic effects are poorly studied.

Methods

We analysed the effect of iron sucrose, ferric carboxymaltose, iron isomaltoside 1000, low-molecular-weight iron dextran and ferumoxytol on classical, intermediate and nonclassical monocyte biology. We therefore stimulated in vitro mature monocytes and haematopoietic CD34⁺ stem cells during their differentiation into monocytes with different concentrations (0.133, 0.266, 0.533 mg/mL) of i.v. iron preparations. Alterations of monocyte subset distribution, expression of surface markers (CD86, CCR5, CX₃CR1), as well as production of pro-inflammatory cytokines (TNF-α, IL-1β) and reactive oxygen species were measured using flow cytometry. Additionally, we analysed phagocytosis and antigen presentation capacity.

Results

We found specific immunologic effects after stimulation with iron sucrose which were not induced by the other iron preparations. Iron sucrose activated monocyte subsets leading to significantly increased CD86 expression. Simultaneously CD16 and CX₃CR1 expression and monocytic phagocytosis capacity were decreased. Additionally, differentiation of monocytes from haematopoietic CD34⁺ stem cells was almost completely abolished after stimulation with iron sucrose.

Conclusions

Our findings demonstrate that specific immunologic effects of distinct i.v. iron preparations exist. The clinical relevance of these findings requires further investigation.

Washing older blood units before transfusion reduces plasma iron and improves outcomes in experimental canine pneumonia

In a randomized controlled blinded trial, 2-year-old purpose-bred beagles (n = 24), with Staphylococcus aureus pneumonia, were exchanged-transfused with either 7- or 42-day-old washed or unwashed canine universal donor blood (80 mL/kg in 4 divided doses). Washing red cells (RBC) before transfusion had a significantly different effect on canine survival, multiple organ injury, plasma iron, and cell-free hemoglobin (CFH) levels depending on the age of stored blood (all, P < .05 for interactions). Washing older units of blood improved survival rates, shock score, lung injury, cardiac performance and liver function, and reduced levels of non-transferrin bound iron and plasma labile iron. In contrast, washing fresh blood worsened all these same clinical parameters and increased CFH levels. Our data indicate that transfusion of fresh blood, which results in less hemolysis, CFH, and iron release, is less toxic than transfusion of older blood in critically ill infected subjects. However, washing older blood prevented elevations in plasma circulating iron and improved survival and multiple organ injury in animals with an established pulmonary infection. Our data suggest that fresh blood should not be washed routinely because, in a setting of established infection, washed RBC are prone to release CFH and result in worsened clinical outcomes.

The complex interplay of iron metabolism, reactive oxygen species, and reactive nitrogen species: insights into the potential of various iron therapies to induce oxidative and nitrosative stress

Production of minute concentrations of superoxide (O2(*-)) and nitrogen monoxide (nitric oxide, NO*) plays important roles in several aspects of cellular signaling and metabolic regulation. However, in an inflammatory environment, the concentrations of these radicals can drastically increase and the antioxidant defenses may become overwhelmed. Thus, biological damage may occur owing to redox imbalance-a condition called oxidative and/or nitrosative stress. A complex interplay exists between iron metabolism, O2(*-), hydrogen peroxide (H2O2), and NO*. Iron is involved in both the formation and the scavenging of these species. Iron deficiency (anemia) (ID(A)) is associated with oxidative stress, but its role in the induction of nitrosative stress is largely unclear. Moreover, oral as well as intravenous (iv) iron preparations used for the treatment of ID(A) may also induce oxidative and/or nitrosative stress. Oral administration of ferrous salts may lead to high transferrin saturation levels and, thus, formation of non-transferrin-bound iron, a potentially toxic form of iron with a propensity to induce oxidative stress. One of the factors that determine the likelihood of oxidative and nitrosative stress induced upon administration of an iv iron complex is the amount of labile (or weakly-bound) iron present in the complex. Stable dextran-based iron complexes used for iv therapy, although they contain only negligible amounts of labile iron, can induce oxidative and/or nitrosative stress through so far unknown mechanisms. In this review, after summarizing the main features of iron metabolism and its complex interplay with O2(*-), H2O2, NO*, and other more reactive compounds derived from these species, the potential of various iron therapies to induce oxidative and nitrosative stress is discussed and possible underlying mechanisms are proposed. Understanding the mechanisms, by which various iron formulations may induce oxidative and nitrosative stress, will help us develop better tolerated and more efficient therapies for various dysfunctions of iron metabolism.

The comparative short-term effectiveness of iron dosing and formulations in US hemodialysis patients

BACKGROUND

Intravenous iron is used widely in hemodialysis, yet there are limited data on the effectiveness of contemporary dosing strategies or formulation type.

METHODS

We conducted a retrospective cohort study using data from the clinical database of a large dialysis provider (years 2004-2008) merged with administrative data from the US Renal Data System to compare the effects of intravenous iron use on anemia management. Dosing comparisons were bolus (consecutive doses ≥100 mg exceeding 600 mg during 1 month) versus maintenance (all other iron doses during the month); and high (>200 mg over 1 month) versus low dose (≤200 mg over 1 month). Formulation comparison was administration of ferric gluconate versus iron sucrose over 1 month. Outcomes were hemoglobin, epoetin dose, transferrin saturation, and serum ferritin during 6 weeks of follow-up.

RESULTS

We identified 117,050 patients for the dosing comparison, and 66,207 patients for the formulation comparison. Bolus dosing was associated with higher average adjusted hemoglobin (+0.23 g/dL; 95% confidence interval [CI], 0.21-0.26), transferrin saturation (+3.31%; 95% CI, 2.99-3.63), serum ferritin (+151 μg/L; 95% CI, 134.9-168.7), and lower average epoetin dose (-464 units; 95% CI, -583 to -343) compared with maintenance. Similar trends were observed with high-dose iron versus low-dose. Iron sucrose was associated with higher adjusted average hemoglobin (+0.16 g/dL; 95% CI, 0.12-0.19) versus ferric gluconate.

CONCLUSIONS

Strategies favoring large doses of intravenous iron or iron sucrose lead to improved measures of anemia management. These potential benefits should be weighed against risks, which currently remain incompletely characterized.

A specific immune transcriptomic profile discriminates chronic kidney disease patients in predialysis from hemodialyzed patients

BACKGROUND

Chronic kidney disease (CKD) patients present a complex interaction between the innate and adaptive immune systems, in which immune activation (hypercytokinemia and acute-phase response) and immune suppression (impairment of response to infections and poor development of adaptive immunity) coexist. In this setting, circulating uremic toxins and microinflammation play a critical role. This condition, already present in the last stages of renal damage, seems to be enhanced by the contact of blood with bioincompatible extracorporeal hemodialysis (HD) devices. However, although largely described, the cellular machinery associated to the CKD- and HD-related immune-dysfunction is still poorly defined. Understanding the mechanisms behind this important complication may generate a perspective for improving patients outcome.

METHODS

To better recognize the biological bases of the CKD-related immune dysfunction and to identify differences between CKD patients in conservative (CKD) from those in HD treatment, we used an high-throughput strategy (microarray) combined with classical bio-molecular approaches.

RESULTS

Immune transcriptomic screening of peripheral blood mononuclear cells (1030 gene probe sets selected by Gene-Ontology) showed that 275 gene probe sets (corresponding to 213 genes) discriminated 9 CKD patients stage III-IV (mean±SD of eGFR: 32.27+/-14.7 ml/min) from 17 HD patients (p<0.0001, FDR=5%). Seventy-one genes were up- and 142 down-regulated in HD patients. Functional analysis revealed, then, close biological links among the selected genes with a pivotal role of PTX3, IL-15 (up-regulated in HD) and HLA-G (down-regulated in HD). ELISA, performed on an independent testing-group [11 CKD stage III-IV (mean±SD of eGFR: 30.26±14.89 ml/min) and 13 HD] confirmed that HLA-G, a protein with inhibition effects on several immunological cell lines including natural killers (NK), was down-expressed in HD (p=0.04). Additionally, in the testing-group, protein levels of CX3CR1, an highly selective chemokine receptor and surface marker for cytotoxic effector lymphocytes, resulted higher expressed in HD compared to CKD (p<0.01).

CONCLUSION

Taken together our results show, for the first time, that HD patients present a different immune-pattern compared to the un-dialyzed CKD patients. Among the selected genes, some of them encode for important biological elements involved in proliferation/activation of cytotoxic effector lymphocytes and in the immune-inflammatory cellular machinery. Additionally, this study reveals new potential diagnostic bio-markers and therapeutic targets.

Kidney Disease: Improving Global Outcomes guidelines on anaemia management in chronic kidney disease: a European Renal Best Practice position statement

Recently, the Kidney Disease: Improving Global Outcomes (KDIGO) group has produced comprehensive clinical practice guidelines for the management of anaemia in CKD patients. These guidelines addressed all of the important points related to anaemia management in CKD patients, including therapy with erythropoieis stimulating agents (ESA), iron therapy, ESA resistance and blood transfusion use. Because most guidelines were 'soft' rather than 'strong', and because global guidelines need to be adapted and implemented into the regional context where they are used, on behalf of the European Renal Best Practice Advisory Board some of its members, and other external experts in this field, who were not participants in the KDIGO guidelines group, were invited to participate in this anaemia working group to examine and comment on the KDIGO documents in this position paper. In this article, the group concentrated only on those guidelines which we considered worth amending or adapting. All guidelines not specifically mentioned are fully endorsed.

Anaemia in inflammatory rheumatic diseases

Anaemia is frequently observed in patients with inflammatory rheumatic diseases. Depending on its severity, anaemia negatively affects cardiovascular performance, physical activity and the quality of life of patients. However, anaemia is considered to be a symptom of the underlying inflammatory disease and, thus, neglected as a complex medical condition that warrants specific diagnosis and treatment. Although inflammation-induced alterations in iron homeostasis and erythropoiesis have a dominant role in the pathogenesis of this type of anaemia, multiple other factors such as chronic blood loss, haemolysis, disease and treatment-associated adverse effects or vitamin deficiencies can also take part in the development of anaemia. Accordingly, the prevalence of anaemia is positively associated with the severity of the underlying disease. This Review will summarize epidemiological data on anaemia in inflammatory rheumatic diseases, along with a detailed description of underlying pathophysiological pathways, available diagnostic tools and practical diagnostic strategies. Discussion of established and newly emerging treatment regimens, as well as the need for further research in this clinically relevant field, will also be included.

Iron sucrose promotes endothelial injury and dysfunction and monocyte adhesion/infiltration

BACKGROUND/AIMS

Intravenous (IV) iron preparations are widely used in the management of anemia in ESRD populations. Recent changes in reimbursement policy have dramatically increased the use of IV iron to lower the use of costly erythropoiesis-stimulating agents. These preparations are frequently administered with insufficient attention to the total body iron stores or presence of inflammation which is aggravated by excess iron. Endothelial injury and dysfunction are critical steps in atherosclerosis, thrombosis and cardiovascular disease. IV iron preparations raise plasma non-transferrin-bound iron which can promote oxidative stress, endothelial damage and dysfunction. We explored the effect of an IV iron preparation on endothelial cells, monocytes and isolated arteries.

METHODS

Primary cultures of human aortic endothelial cells (HAEC) were treated with pharmacologically relevant concentrations of iron sucrose (10-100 μg/ml) for 4-24 h. Endothelial cell morphology, viability, and monocyte adhesion were tested. Endothelial function was assessed by measuring the vasorelaxation response to acetylcholine in normal rat thoracic aorta rings preincubated with iron sucrose (200 μg/ml).

RESULTS

In contrast to the control HAEC which showed normal cobblestone appearance, cells treated with iron sucrose (50-100 μg/ml) for 4 h showed loss of normal morphological characteristics, cellular fragmentation, shrinkage, detachment, monolayer disruption and nuclear condensation/fragmentation features signifying apoptosis. HAEC exposure to iron sucrose (10-100 μg/ml) increased monocyte adhesion 5- to 25-fold. Incubation in media containing 200 μg/ml iron sucrose for 3 h caused marked reduction in the acetylcholine-mediated relaxation in phenylephrine-precontracted rat aorta.

CONCLUSION

Pharmacologically relevant concentration of iron sucrose results in endothelial injury and dysfunction and marked increase in monocyte adhesion.