Effect of Deferoxamine on Post-Transfusion Iron, Inflammation, and In Vitro Microbial Growth in a Canine Hemorrhagic Shock Model: A Randomized Controlled Blinded Pilot Study.

Red blood cell (RBC) transfusion is associated with recipient inflammation and infection, which may be triggered by excessive circulating iron. Iron chelation following transfusion may reduce these risks. The aim of this study was to evaluate the effect of deferoxamine on circulating iron and inflammation biomarkers over time and in vitro growth of Escherichia coli (E. coli) following RBC transfusion in dogs with atraumatic hemorrhage. Anesthetized dogs were subject to atraumatic hemorrhage and transfusion of RBCs, then randomized to receive either deferoxamine or saline placebo of equivalent volume (n = 10 per group) in a blinded fashion. Blood was sampled before hemorrhage and then 2, 4, and 6 h later. Following hemorrhage and RBC transfusion, free iron increased in all dogs over time (both p < 0.001). Inflammation biomarkers interleukin-6 (IL6), CXC motif chemokine-8 (CXCL8), interleukin-10 (IL10), and keratinocyte-derived chemokine (KC) increased in all dogs over time (all p < 0.001). Logarithmic growth of E. coli clones within blood collected 6 h post-transfusion was not different between groups. Only total iron-binding capacity was different between groups over time, being significantly increased in the deferoxamine group at 2 and 4 h post-transfusion (both p < 0.001). In summary, while free iron and inflammation biomarkers increased post-RBC transfusion, deferoxamine administration did not impact circulating free iron, inflammation biomarkers, or in vitro growth of E. coli when compared with placebo.

Labile plasma iron and echocardiographic parameters are associated with cardiac events in ß-thalassemic patients.

BACKGROUND AND AIM: Notwithstanding the improvement in therapies, patients affected by thalassemia major (TM) and intermedia (TI) are still at high risk of cardiac complications. This study aimed at evaluating the incidence and predictive factors for developing cardiac events in adult ß-TM and TI patients. POPULATION AND METHODS: Data on diagnosis and clinical history were collected retrospectively; prospective data on new-onset cardiac failure and arrhythmias, echocardiographic parameters, biochemical variables including non-transferrin-bound iron (NTBI) and labile plasma iron (LPI), magnetic resonance imaging (MRI) T2* measurement of hepatic and cardiac iron deposits, and iron chelation therapy were recorded during a 6-year follow-up. RESULTS: Thirty-seven patients, 29 TM and 8 TI, were included. At baseline, 8 TM patients and 1 TI patient had previously experienced a cardiac event (mainly heart failure). All patients were on chelation therapy and only 3 TM patients had mild-to-severe cardiac siderosis. During follow-up, 11 patients (29.7%) experienced a new cardiac event. The occurrence of cardiac events was correlated to high LPI levels (OR 12.0, 95% CI 1.56-92.3, p .017), low mean pre-transfusion haemoglobin (OR 0.21, 95% C.I. 0.051-0.761, p .21) and echocardiographic parameters suggestive of myocardial hypertrophy. Multivariate analysis disclosed high LPI and left ventricle mass index (LVMI) as independent variables significantly associated with cardiac events. Cardiac iron deposits measured by MRI T2* failed to predict cardiac events. CONCLUSION: LPI, Hb levels and echocardiographic parameters assessing cardiac remodelling are associated with cardiac events in adult TM and TI patients. LPI might represent both a prognostic marker and a potential target for novel treatment strategies. Further studies are warranted to confirm our findings on larger populations.

Iron, ferroptosis, and new insights for prevention in acute kidney injury.

Acute kidney injury (AKI) is a very common condition with high morbidity and mortality, which can be seen in 5-7% of all hospitalized patients and in up to 57% of all intensive care unit admissions. Despite recent advances in clinical care, the prevalence of AKI has been shown to increase with virtually no change in mortality. AKI is a complex syndrome occurring in a variety of clinical settings. Early detection is crucial to prevent irreversible loss of renal function. The pathogenesis of AKI is highly multifactorial and complex, including vasoconstriction, reactive oxygen species formation, cell death, abnormal immune modulators and growth factors. Emerging evidence from both human and animal studies suggests that dysregulation of iron metabolism may play a potentially important role in AKI. Therefore, targeting the iron homeostasis may provide a new therapeutic intervention for AKI. New therapeutic strategies including iron chelation therapy, targeting iron metabolism related proteins and direct inhibitors of ferroptosis are imperative to improve the outcomes of patients. Taking into consideration the complexity of AKI, one intervention may not be enough for therapeutic success. Future preclinical studies in animal disease models followed by well-designed clinical trials should be conducted to extend findings from animal AKI models to humans.

Labile plasma iron levels in chronic hemodialysis patients treated by intravenous iron supplementation.

The increased usage of intravenous iron in hemodialysis patients during recent years has led to increasing concern over the potential development of iron overload. Current methods for detecting iron overload, transferrin saturation, and serum ferritin are neither sensitive nor specific. Labile plasma iron (LPI) represents a component of nontransferrin-bound iron and may be a more accurate indicator of impending iron overload. We studied whether LPI measured can serve as an early indicator of impending iron overload and mortality in hemodialysis patients. Chronic hemodialysis patients from two medical centers in Israel and Poland who received intravenous iron were included. Baseline clinical and laboratory parameters were recorded. LPI was measured before and 48 hours after a single IV administration. Correlation of positive LPI with laboratory parameters and 2-year mortality was evaluated. One hundred and one hemodialysis patients were included in the study. LPI became positive post-administration in 18 (17.8%) patients. Ferritin levels >526 ng/mL and monthly iron doses >250 mg were associated with positive LPI after intravenous iron. At a 2-year follow-up, higher mortality was observed in the positive LPI group (61.1% compared to 25.3%, P ≤ .05), although this effect was not statistically significant after multivariate adjustment. A substantial number of hemodialysis patients have positive LPI after intravenous iron administration. LPI positively correlates with laboratory parameters that are currently in routine clinical use for detecting iron overload and with higher intravenous iron dose. Further studies should be conducted to establish the clinical implications of LPI monitoring in hemodialysis patients.

Utility of Labile Plasma Iron Assay in Thalassemia Major Patients.

Labile plasma iron (LPI) levels are proposed as marker of iron overload in thalassemia patients and are also known to be the earliest parameter to indicate efficacy of chelation therapy. It was a prospective study in 35 patients of thalassemia major. Patients were recruited in two groups-group A (n = 13) patients not on chelation therapy and group B (n = 22) patients who were on regular oral chelation therapy. Ten age and gender matched healthy controls were also studied. For all patients, ferritin levels and LPI levels were measured at baseline, 6 months and 12 months. For group B patients paired samples for LPI were taken (before and 2 h after chelator). LPI levels were found to be significantly higher in group B patients versus group A patients versus normal healthy controls at all time-points. (P value-< 0.0001, 0.001) In group A, both LPI levels and ferritin levels follow an upward trend and correlated well with each other (P value-< 0.0001). In group B, the serum ferritin trend was not significant over follow up period of 1 year (P value 0.16), however LPI levels showed a significant decreasing trend on continued chelation (P value 0.0347) In patients on chelation therapy, the immediate change (2 h) in LPI levels on administration of chelators was not found to be significant (P value 0.22). LPI assay appears potentially attractive alternate to serum ferritin and can serve to monitor the trend of iron overload during long-term follow up.

Non-transferrin-bound iron transporters.

Most cells in the body acquire iron via receptor-mediated endocytosis of transferrin, the circulating iron transport protein. When cellular iron levels are sufficient, the uptake of transferrin decreases to limit further iron assimilation and prevent excessive iron accumulation. In iron overload conditions, such as hereditary hemochromatosis and thalassemia major, unregulated iron entry into the plasma overwhelms the carrying capacity of transferrin, resulting in non-transferrin-bound iron (NTBI), a redox-active, potentially toxic form of iron. Plasma NTBI is rapidly cleared from the circulation primarily by the liver and other organs (e.g., pancreas, heart, and pituitary) where it contributes significantly to tissue iron overload and related pathology. While NTBI is usually not detectable in the plasma of healthy individuals, it does appear to be a normal constituent of brain interstitial fluid and therefore likely serves as an important source of iron for most cell types in the CNS. A growing body of literature indicates that NTBI uptake is mediated by non-transferrin-bound iron transporters such as ZIP14, L-type and T-type calcium channels, DMT1, ZIP8, and TRPC6. This review provides an overview of NTBI uptake by various tissues and cells and summarizes the evidence for and against the roles of individual transporters in this process.

Labile plasma iron as an indicator of patient adherence to iron chelation treatment.

Poor adherence of transfusion-dependent patients to chelation treatment is often the cause of persistent iron overload and ensuing morbidity. However, a tool to assess patient compliance with therapy is lacking in clinical practice. Labile plasma iron (LPI, the redox-active component of non-transferrin bound iron) has been studied as an indicator of systemic iron overload and of chelation efficacy, and may particularly reflect recent iron equilibrium. We considered the use of LPI as a potential indicator for recent chelation treatment in 18 transfusion-dependent pediatric patients. Samples were collected under chelation treatment or after a short interruption of the treatment, and LPI was measured by the FeROS assay (Aferrix, Tel Aviv, Israel). LPI was significantly higher after a short-term interruption of the chelation (median of 0.4 µM off-therapy [range:0-4] vs 0 µM on-therapy [range:0-2.8] (p < .001)). Conversely, serum iron, serum ferritin and calculated transferrin saturation were not significantly higher in the "off-therapy" samples compared to "on-therapy". In addition, in multivariate logistic regression analysis LPI was the variable most significantly associated with recent chelation treatment (p = .001). We conclude that LPI could serve as a useful indicator of compliance to chelation therapy.

Hemochromatosis: a model of metal-related human toxicosis.

Many environmental agents, such as excessive alcohol intake, xenobiotics, and virus, are able to damage the human body, targeting especially the liver. Metal excess may also assault the liver. Thus, chronic iron overload may cause, especially when associated with cofactors, diffuse organ damage that is a source of significant morbidity and mortality. Iron excess can be either of acquired (mostly transfusional) or of genetic origin. Hemochromatosis is the archetype of genetic iron overload diseases and represents a serious health problem. A better understanding of iron metabolism has deeply modified the hemochromatosis field which today benefits from much more efficient diagnostic and therapeutic approaches.

Citrate and albumin facilitate transferrin iron loading in the presence of phosphate.

Labile plasma iron (LPI) is redox active, exchangeable iron that catalyzes the formation of reactive oxygen species. Serum transferrin binds iron in a non-exchangeable form and delivers iron to cells. In several inflammatory diseases serum LPI increases but the reason LPI forms is unknown. This work evaluates possible pathways leading to LPI and examines potential mediators of apo transferrin iron loading to prevent LPI. Previously phosphate was shown to inhibit iron loading into apo transferrin by competitively binding free Fe3+. The reaction of Fe3+ with phosphate produced a soluble ferric phosphate complex. In this study we evaluate iron loading into transferrin under physiologically relevant phosphate conditions to evaluate the roles of citrate and albumin in mediating iron delivery into apo transferrin. We report that preformed Fe3+-citrate was loaded into apo transferrin and was not inhibited by phosphate. A competition study evaluated reactions when Fe3+ was added to a solution with citrate, phosphate and apo transferrin. The results showed citrate marginally improved the delivery of Fe3+ to apo transferrin. Studies adding Fe3+ to a solution with phosphate, albumin and apo transferrin showed that albumin improved Fe3+ loading into apo transferrin. The most efficient Fe3+ loading into apo transferrin in a phosphate solution occurred when both citrate and albumin were present at physiological concentrations. Citrate and albumin overcame phosphate inhibition and loaded apo transferrin equal to the control of Fe3+ added to apo transferrin. Our results suggest a physiologically important role for albumin and citrate for apo transferrin iron loading.

Labile plasma iron, more practical and more sensitive to iron overload in myelodysplastic syndromes.

OBJECTIVES: In order to gain an insight into labile plasma iron (LPI) in iron metabolism microenvironment in MDS. METHODS: We performed ELISA, quantitative real-time polymerase chain reaction, flow cytometry, MRI T2* assays to test LPI, iron biochemical parameters, and liver iron concentration (LIC) among 22 MDS patients. RESULTS: LPI has a statistical difference (P < 0.001 by analysis of variance (ANOVA)), which decreased gradually, among three groups, while no difference was found in adjusted serum ferritin (ASF) (P = 0.086 by ANOVA). After DFO treatment, serum hepcidin expression increased from 301.26 ± 59.78 to 340.33 ± 49.78 µg/l (P = 0.032), while hepcidin/ASF was upregulated gradually from 0.16 ± 0.08 to 0.22 ± 0.03 (P = 0.045). APAF-1 expression (P = 0.047) and erythroid apoptosis rate (P = 0.009) decreased significantly, respectively. No statistical difference was found in EPO (P = 0.247) and GDF15 expression (P = 0.172). LIC dropped from 9.83 ± 4.84 to 6.28 ± 4.01 mg/g dry weight (P < 0.001). No significant difference was found in cardiac T2* (P = 0.594). LPI has a closer connection to LIC than ASF (r = 0.739, P < 0.001 vs. r = 0.321, P = 0.034). DISCUSSION: LPI seems to be a real-time indicator which reflects body iron loading status instantaneously. Despite the limited knowledge available on LPI speciation in different types and degrees of IO, LPI measurements can be and are in fact used for identifying systemic IO and for initiating/adjusting chelation regimens.

Iron Chelation in Thalassemia Major.

PURPOSE: Iron chelation has improved survival and quality of life of patients with thalassemia major. there are currently 3 commercially available iron-chelating drugs with different pharmacokinetic and pharmacodynamic activity. The choice of adequate chelation treatment should be tailored to patient needs and based on up-to-date scientific evidence. METHODS: A review of the most recent literature was performed. FINDINGS: The ability of the chelators to bind the redox active component of iron, labile plasma iron, is crucial for protecting the cells. Chelation therapy should be guided by magnetic resonance imaging that permits the tailoring of therapy according to the needs of the patient because different chelators preferentially clear iron from different sites. Normal levels of body iron seem to decrease the need for hormonal and cardiac therapy. IMPLICATIONS: The 3 chelators currently available have different benefits, different safety profiles, and different acceptance on the part of the patients. Good-quality, well-designed, randomized, long-term clinical trials continue to be needed.

Iron and oxidative stress in cardiomyopathy in thalassemia.

With repeated blood transfusions, patients with thalassemia major rapidly become loaded with iron, often surpassing hepatic metal accumulation capacity within ferritin shells and infiltrating heart and endocrine organs. That pathological scenario contrasts with the physiological one, which is characterized by an efficient maintenance of all plasma iron bound to circulating transferrin, due to a tight control of iron ingress into plasma by the hormone hepcidin. Within cells, most of the acquired iron becomes protein-associated, as once released from endocytosed transferrin, it is used within mitochondria for the synthesis of protein prosthetic groups or it is incorporated into enzyme active centers or alternatively sequestered within ferritin shells. A few cell types also express the iron extrusion transporter ferroportin, which is under the negative control of circulating hepcidin. However, that system only backs up the major cell regulated iron uptake/storage machinery that is poised to maintain a basal level of labile cellular iron for metabolic purposes without incurring potentially toxic scenarios. In thalassemia and other transfusion iron-loading conditions, once transferrin saturation exceeds about 70%, labile forms of iron enter the circulation and can gain access to various types of cells via resident transporters or channels. Within cells, they can attain levels that exceed their ability to chemically cope with labile iron, which has a propensity for generating reactive oxygen species (ROS), thereby inducing oxidative damage. This scenario occurs in the heart of hypertransfused thalassemia major patients who do not receive adequate iron-chelation therapy. Iron that accumulates in cardiomyocytes forms agglomerates that are detected by T2* MRI. The labile forms of iron infiltrate the mitochondria and damage cells by inducing noxious ROS formation, resulting in heart failure. The very rapid relief of cardiac dysfunction seen after intensive iron-chelation therapy in some patients with thalassemia major is thought to be due to the relief of the cardiac mitochondrial dysfunction caused by oxidative stress or to the removal of labile iron interference with calcium fluxes through cardiac calcium channels. In fact, improvement occurs well before there is any significant improvement in the total level of cardiac iron loading. The oral iron chelator deferiprone, because of its small size and neutral charge, demonstrably enters cells and chelates labile iron, thereby rapidly reducing ROS formation, allowing better mitochondrial activity and improved cardiac function. Deferiprone may also rapidly improve arrhythmias in patients who do not have excessive cardiac iron. It maintains the flux of iron in the direction hemosiderin to ferritin to free iron, and it allows clearance of cardiac iron in the presence of other iron chelators or when used alone. To date, the most commonly used chelator combination therapy is deferoxamine plus deferiprone, whereas other combinations are in the process of assessment. In summary, it is imperative that patients with thalassemia major have iron chelators continuously present in their circulation to prevent exposure of the heart to labile iron, reduce cardiac toxicity, and improve cardiac function.