Kidney Iron Deposition Research Articles

Kidney R2* Mapping for Noninvasive Evaluation of Iron Overload in Paroxysmal Nocturnal Hemoglobinuria.

The kidney iron deposition can cause kidney damage and renal insufficiency in paroxysmal nocturnal hemoglobinuria (PNH) patients. Assessment of iron deposition in the kidney is essential for the early diagnosis of renal damage in PNH patients. The purpose of this study was to evaluate kidney R2* (T2* reciprocals) values in PNH patients using the iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL-IQ). Two radiologists measured the R2* values of the renal cortex in 14 PNH patients and 13 healthy volunteers using IDEAL-IQ. Lactate dehydrogenase (LDH), a reliable marker of intravascular hemolysis, was also measured in all participants. The kidney R2* values were significantly higher in PNH patients compared with those in healthy volunteers (P < 0.001). High inter-operator reproducibility of the measurements was also acquired using IDEAL-IQ. LDH levels were also significantly higher in PNH patients compared with those in healthy volunteers (P < 0.001). Kidney R2* values strongly correlated with LDH levels in PNH patients. IDEAL-IQ has a possibility of becoming a useful method for the noninvasive evaluation of renal iron overload in PNH patients.

Shenshuaifu Granule Attenuates Acute Kidney Injury by Inhibiting Ferroptosis Mediated by p53/SLC7A11/GPX4 Pathway.

Acute kidney injury (AKI) is a common clinical condition resulting in a rapid decline in renal function, and requires improvement in effective preventive measures. Ferroptosis, a novel form of cell death, is closely related to AKI. Shenshuaifu granule (SSF) has been demonstrated to prevent AKI through suppressing inflammation and apoptosis. This study aimed to explore whether SSF can inhibit ferroptosis in AKI. Active ingredients in SSF were detected through HPLC-MS/MS, and their binding abilities with ferroptosis were evaluated by molecular docking. Then, male C57/BL/6J mice were randomly divided into control, cisplatin, and cisplatin+SSF groups. In the latter two groups, mice were intraperitoneally injected with 20 mg/kg of cisplatin. For five consecutive days prior to cisplatin injection, mice in the cisplatin+SSF group were gavaged with 5.2 g/kg of SSF per day.72 h after cisplatin injection, the mice were sacrificed. Serum creatinine (SCr) and blood urea nitrogen (BUN) were measured to evaluate renal function. H&E and PAS staining were used to observe pathological damage of kidney. Cell death was observed by TUNEL staining, and iron accumulation in kidneys of mice was detected by Prussian blue staining. Western blotting, immunohistochemistry, and immunofluorescence were used to investigate the presence of inflammation, oxidative stress, mitochondrial dysfunction, iron deposition, and lipid peroxidation in mouse kidneys. Active ingredients in SSF had strong affinities with ferroptosis. SSF reduced SCr (p<0.01) and BUN (p<0.0001) levels, pathological damage (p<0.0001), dead cells in the tubular epithelium (p<0.0001) and iron deposition (p<0.01) in mice with cisplatin induced AKI. And SSF downregulated macrophage infiltration (p<0.01), the expressions of high mobility group box 1 (HMGB1, p<0.05) and interleukin (IL)-17 (p<0.05), upregulated superoxide dismutase (SOD) 1 and 2 (p<0.01), and catalase (CAT, p<0.05), and alleviated mitochondrial dysfunction (p<0.05). More importantly, SSF regulated iron transport and intracellular iron overload and reduced the expression of ferritin (p<0.05). Moreover, it downregulated the expressions of cyclo-oxygenase-2 (Cox-2, p<0.001), acid CoA ligase 4 (ACSL4, p<0.05), and solute carrier family 7, member 11 (SLC7A11, p<001), upregulated glutathione peroxidase 4 (GPX4, p<0.01) and p53 (p<0.01), and decreased 4-hydroxynonenal (4-HNE) level (p<0.001). SSF attenuates AKI by inhibiting ferroptosis mediated by p53/SLC7A11/GPX4 pathway.

Ferroptosis, a new target for treatment of renal injury and fibrosis in a 5/6 nephrectomy-induced CKD rat model

Ferroptosis is a non-traditional form of regulated cell death, characterized by iron overload and lipid peroxidation. Exploration of ferroptosis in chronic kidney disease (CKD) has been extremely limited to date. In this study, we established a rat model of CKD by 5/6 nephrectomy, treated CKD rats with the ferroptosis inducer, cisplatin (CDDP), and the ferroptosis inhibitor, deferoxamine mesylate (DFO), and observed the resulting pathologic changes (injury markers and fibrosis) and ferroptotic biochemical indices. Kidney iron deposition, lipid peroxidation, mitochondrial defects, ferroptosis marker induction, and TUNEL staining positivity were detected in CKD group rats. Further, treatment with CDDP or DFO influenced renal injury and fibrosis by affecting ferroptosis, rather than apoptosis, and ferroptosis occurs in the remnant kidney due to disordered iron metabolism. In conclusion, our study shows for the first time that 5/6 nephrectomy induces ferroptosis in the remnant kidney and clarifies the underlying pathogenesis. Moreover, we demonstrate that ferroptosis is involved in CKD progression and represents a therapeutic target in chronic kidney injury and renal fibrosis.

Kidney tubule iron loading in experimental focal segmental glomerulosclerosis

Kidney iron deposition may play a role in the progression of tubulointerstitial injury during chronic kidney disease. Here, we studied the molecular mechanisms of kidney iron loading in experimental focal segmental glomerulosclerosis (FSGS) and investigated the effect of iron-reducing interventions on disease progression. Thy-1.1 mice were injected with anti-Thy-1.1 monoclonal antibody (mAb) to induce proteinuria. Urine, blood and tissue were collected at day (D)1, D5, D8, D15 and D22 after mAb injection. Thy-1.1 mice were subjected to captopril (CA), iron-deficient (ID) diet or iron chelation (deferoxamine; DFO). MAb injection resulted in significant albuminuria at all time points (p < 0.01). Kidney iron loading, predominantly in distal tubules, increased in time, along with urinary kidney injury molecule-1 and 24p3 concentration, as well as kidney mRNA expression of Interleukin-6 (Il-6) and Heme oxygenase-1 (Ho-1). Treatment with CA, ID diet or DFO significantly reduced kidney iron deposition at D8 and D22 (p < 0.001) and fibrosis at D22 (p < 0.05), but not kidney Il-6. ID treatment increased kidney Ho-1 (p < 0.001). In conclusion, kidney iron accumulation coincides with progression of tubulointerstitial injury in this model of FSGS. Reduction of iron loading halts disease progression. However, targeted approaches to prevent excessive kidney iron loading are warranted to maintain the delicate systemic and cellular iron balance.

Frequency, Pattern, and Associations of Renal Iron Accumulation in Sickle Beta-Thalassemia

▪Background: Chronically transfused homozygous sickle cell disease (HbSS) patients were shown to have higher kidney iron deposition than thalassemia major patients, not associated to total body iron and mainly caused by chronic hemolysis. Kidney iron deposition has not been explored in sickle beta-thalassemia (Sβ-thal), resulting from the inheritance of both sickle cell and beta-thalssemia genes.Aim: This multi center study aimed to study frequency, pattern, and associations of renal iron accumulation in sickle beta-thalassemia.Methods: Thirty-three Sβ-thal patients (36.49±14.72 years; 13 females) consecutively enrolled in the Extension-Myocardial Iron Overload in Thalassemia (E-MIOT) network were considered. Moreover, 20 healthy subjects, 14 HbSS patients and 71 thalassemia major (TM) patients were included as comparison groups. Hepatic, cardiac, pancreatic, and renal iron overload was quantified by the gradient-echo T2* technique. In each kidney T2* was measured in anterior, posterolateral, and posteromedial parenchymal regions and the global T2* value was calculated as the average of the two kidneys T2* values.Results. Global renal T2* were significantly higher in healthy subjects versus both Sβ-thal patients (49.68±10.09 ms vs 43.19±8.07 ms; P=0.013) and HbSS patients (49.68±10.09 ms vs 26.21±17.07 ms; P<0.0001).Sβ-thal patients showed comparable age, sex, frequency of regular transfusion, hematochemical parameters, and hepatic, cardiac and pancreatic iron load than HbSS patients, but they had a significant lower frequency of renal iron overload (global renal T2*<31 ms) (9.1% vs 57.1%; P=0.001).Regularly transfused patients (16 Sβ-thal and 10 HbSS) were compared with TM patients, homogeneous for age and sex, but TM started regular transfusions significantly earlier and they were more frequently chelated. No significant difference was detected in terms of hepatic and cardiac iron levels, but TM patients had significantly lower pancreas T2* values than both the other two groups and significantly higher global renal T2* values than HbSS patients (42.87±9.43 ms vs 24.39±15.74 ms; P=0.001).In Sβ-thal patients no significant difference was detected between T2* values in left and right kidneys, and global renal T2* values were not associated to age, gender, splenectomy, and they were comparable between regularly transfused and non transfused patients.No correlation was detected between renal T2* values and serum ferritin levels or iron load in the other organs.Global renal T2* values were not associated with serum creatinine levels but showed a significant inverse correlation with serum lactate dehydrogenase (Figure 1).Conclusion. Renal iron deposition is not common in Sβ-thal patients, with a prevalence significantly lower compared to that of HbSS patients, but with a similar underlying mechanism due to the chronic hemolysis. [Display omitted] DisclosuresPepe: Bayer S.p.A.: Other: no profit support; Chiesi Farmaceutici S.p.A: Other: no profit support. Maggio: Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene Corp: Membership on an entity's Board of Directors or advisory committees; Bluebird Bio: Membership on an entity's Board of Directors or advisory committees.

Kidney Iron Deposition By R2* Is Associated with Hemolysis and Urinary Iron

Introduction Kidney iron deposition has been described in hemolytic disorders including mechanical valves, paroxysmal nocturnal hematuria, and sickle cell disease (Roberts &amp; Morrow, Circulation 1966; Leonardi &amp; Ruol, Blood 1960). Circulating plasma hemoglobin is filtered at the glomerulus and reabsorbed via the megalin cubulin system in the proximal and distal tubules (Gburek et al, J Am Soc Nephrol 2002). On MRI, this manifests as signal loss on gradient and spin echo sequences in the cortex of the kidney with complete sparing of the medulla (Jeong et al, Radiographics 2002). The signal darkening is quantified by the parameter R2*, which has been shown to be directly proportional to tissue iron in the liver and heart. Kidney R2* has previously been demonstrated to rise proportionally to lactate dehydrogenase (LDH) in chronically transfused sickle cell disease (SCD) patients (Wood et al, Br J Haematol 2016; Schein et al, J Magn Reson Imaging 2008), but LDH is not a specific marker of hemolysis, and chronically transfused patients could potentially deposit iron in the kidney through other mechanisms. Therefore, we characterized the relationship between kidney R2*, urinary iron and markers of hemolysis in non-transfused SCD patients. Methods Sixty-five non-transfused SCD patients were recruited to the study, which was approved by the Institutional Review Board of Children's Hospital Los Angeles. Following medical history and physical exam, subjects completed blood and urine testing, and then abdominal MRI for assessment of somatic iron stores. R2* measurements were collected using multiple gradient echo pulse sequences on 1.5 Tesla magnets. Statistical analysis was performed using JMP® Pro, Version 14.0.0 (SAS Institute Inc., Cary, NC, 2018). Results Subjects were generally adults with a mean age of 32 years. Nearly three quarters of subjects had homozygous sickle cell disease, while a quarter had SC disease or S-Beta thalassemia, and one subject had sickle cell trait. Most subjects were anemic, and all subjects had elevated markers of hemolysis. Fifty-four percent of subjects had an elevated kidney R2* level (≥34 Hz). On univariate analysis, kidney R2* was associated with urinary iron (R2=0.52, p&amp;lt;0.0001), LDH (R2=0.33, p&amp;lt;0.0001), plasma hemoglobin (R2=0.18, p=0.0007), and hemoglobin (R2=0.08, p=0.02), but it was not associated with reticulocyte count. On multivariate analysis, kidney R2* was associated with urinary iron and LDH (Figure 1). No association was found between R2* values of the kidney, liver, and pancreas. Discussion Our study supports previous findings that kidney R2* is associated with intravascular hemolysis, as measured by plasma hemoglobin and LDH, and inversely by hemoglobin (Kato et al, Blood 2006). The stronger association with urinary iron reinforces the concept that kidney R2* reflects filtered iron, which is insufficiently reabsorbed due to proximal and distal tubular injury in iron overload (van Raaij et al, Am J Physiol Renal Physiol 2019). Urinary iron is also elevated in diabetic nephropathy (Van et al, J Am Soc Nephrol 2017) and nephrotic syndrome (Niel et al, Blood 2011). These data raise important questions regarding the possible role of iron in sickle related renal disease. Disclosures Coates: apo pharma: Consultancy, Honoraria, Speakers Bureau; vifor: Consultancy, Honoraria; agios pharma: Consultancy, Honoraria; celgene: Consultancy, Honoraria, Other: steering committee of clinical study. Wood:National Institutes of Health: Research Funding; Philips Healthcare: Research Funding; BluebirdBio: Consultancy; Celgene: Consultancy; Apopharma: Consultancy; WorldcareClinical: Consultancy; BiomedInformatics: Consultancy; Imago Biosciences: Consultancy.

Is Magnetic Resonance Imaging Detection of Kidney Iron Deposition Increased in Haptoglobin 2-2 Genotype Carriers with Type 1 Diabetes?

Haptoglobin's (Hp) main role is to bind free hemoglobin (Hb), reducing its oxidative potential. The Hp-Hb complex formed is cleared from the circulation by macrophage receptor CD163. In diabetes, impaired Hp 2-2-Hb CD163 clearance and abnormal glomerular permeability allow the large Hp 2-2-Hb complex to cross the barrier, where its redox active iron leads to cellular toxicity. Although Hp 2-2 predicts renal function decline, whether renal iron deposition differs by Hp is unknown. We used renal quantitative T2* magnetic resonance imaging to estimate iron level in the cortex and medullar of type 1 diabetes (T1D) adults [15 Hp 1-1 and 15 Hp 2-2 carriers of similar age (53 years), duration (45 years), and gender]. Total kidney iron level was estimated as the sum of the cortex and medullar iron. Albuminuria was defined as urinary albumin to creatinine ratio >30 mg/g in two of three samples. Total kidney iron did not differ by gender or Hp but was higher in those with albuminuria (p = 0.05), an association confined to Hp 2-2 carriers (p = 0.04 vs. p = 0.51 in Hp 1-1). These data lead to the hypothesis that kidney iron deposition is increased among Hp 2-2 carriers with albuminuria in T1D. Antioxid. Redox Signal. 29, 735-741.

Magnetic Resonance Imaging Findings in Neonatal Hemochromatosis.

There are limited data on utility of magnetic resonance imaging (MRI) in the assessment of suspected neonatal hemochromatosis (NH). The aim of the study was to present our experience with utilization of multi-echo sequence MRI technique in the evaluation of NH and to compare MRI findings in infants with and without NH. MRI performed for suspected NH were retrospectively reviewed to note the presence and severity of iron deposition (ID) in liver, spleen, pancreas, and kidneys on multi-echo sequences. Findings were compared in infants with and without NH. Of 20 infants (9 boys and 11 girls; median age of 12.5 days) included in the study, 7 of 20 had NH and 13 of 20 were assigned to the non-NH group. Higher degree of pancreatic ID was seen in the NH group (P = 0.001) with 4 of 7 evaluable pancreas showing moderate-to-severe degree and 1 of 7 showing mild degree of ID whereas none of the 13 infants in non-NH group showed moderate or severe degree of pancreatic ID. Even though the severity of hepatic ID was higher in NH group (P = 0.033), variable severity of hepatic ID was seen in both groups with most infants in both groups showing moderate-to-severe degree of ID. The severity of splenic ID was not particularly associated with any group (P = 0.774) but there was no moderate or severe degree of ID in NH. Renal ID was seen in two infants in non-NH group. A moderate-to-severe degree of pancreatic ID seen on MRI tends to be associated with NH and should be sought to establish a timely diagnosis of NH. Presence and severity of hepatic ID cannot be used for differentiation of NH from other causes of neonatal liver failure.

Changes in Extrahepatic Iron Load in Response to Iron Chelation Versus Phlebotomy: Observations from the Twitch Trial

▪Introduction: The TCD with Transfusions Changing to Hydroxyurea (TWiTCH) trial was an NHLBI-funded multicenter phase 3 randomized trial that demonstrated non-inferiority of hydroxyurea versus continued transfusion therapy in children with sickle cell anemia and abnormal TCD velocities but no severe vasculopathy. Children who were randomized to continue transfusions (Standard Arm) received conventional iron chelation therapy with deferasirox, while children receiving hydroxyurea (Alternative Arm) received serial phlebotomy (10 mL/kg, maximum 500 mL) every 4 weeks. Extrahepatic iron burden was monitored by R2* MRI in the kidney, pancreas, and spleen to monitor the changes in iron overload phenotype between the two groups.Methods: R2* MRI of the abdomen was performed at baseline, 1 year, and 2 years following enrollment. Liver, spleen, pancreas, and kidney R2* were measured from axial and coronal multiecho, gradient echo images. Images were analyzed centrally at an experienced core laboratory using an exponential plus constant model for signal decay. Iron burden in the different organs was assessed using repeated measures analysis of variance (ANOVA) using JMP 11.0.Results: 120 patients underwent baseline R2* assessment, 83 completed the midpoint, and 89 patients completed the endpoint examination. Figure 1 (left) summarizes the changes in kidney R2* across the three time points. Kidney R2* was elevated at baseline in both treatment arms and correlated with LDH (r2 =0.28, p<0.0001) and total iron binding capacity, but not with age, sex, LIC, serum ferritin, years of transfusion and years of chelation. Kidney R2* and markers of hemolysis (LDH, total bilirubin), remained stable in the transfusion arm. In contrast, kidney R2* declined monotonically in the patients on hydroxyurea (F value 6.9, p=0.0021 for time-treatment interaction). These changes paralleled reductions in LDH (F value 8.1, p=0.0007) and total bilirubin (F value 28, p<0.0001) in the hydroxyurea group compared to the transfusion group. There were no group differences in mean serum creatinine or urine albumin to creatinine ratio (ACR). However, the frequency and severity of albuminuria (ACR > 30 mg albumin per g creatinine) trended lower in patients on hydroxyurea, (5/45 at baseline (p=1), 1/44 at midpoint (p=0.03), and 4/52 at endpoint (p=0.33). Figure 1 (right) demonstrates the temporal evolution of ACR in 11 study participants with baseline albuminuria; 4/6 patients on standard arm continued to have significant proteinuria on their terminal examination compared with only 1/5 patients on hydroxyurea (p=0.24).There were no groupwise differences in mean pancreas R2* at any time point and clinically significant pancreas iron deposition (R2* > 100 Hz) was only observed in two patients at the mid timepoint. Spleen R2* was markedly elevated at baseline (503 ± 396 Hz), but did not change systematically over time in either group. The change in spleen R2* was correlated with the change in liver iron (r2=0.21, p=0.003), regardless of the treatment group, suggesting that the spleen iron stores are part of the dynamic iron storage pool. 37% of the patients had no MRI-detectable spleen (surgical + autosplenectomy). The change of liver iron was not different in patients with or without a spleen.Conclusion: Hydroxyurea therapy was associated with lower intravascular hemolysis and kidney iron deposition. Further studies are necessary to determine whether these changes are associated with decreased proteinuria or improved renal function. Splenic iron burden remained high but stable in all patients, and its role in iron unloading needs further investigation. Pancreas iron loading remained rare, consistent with the low prevalence of endocrinopathies in SCD. [Display omitted] DisclosuresWood:Apopharma: Consultancy; Ionis Pharmaceuticals: Consultancy; Vifor: Consultancy; Vifor: Consultancy; Biomed Informatics: Consultancy; AMAG: Consultancy; Biomed Informatics: Consultancy; Ionis Pharmaceuticals: Consultancy; World Care Clinical: Consultancy; World Care Clinical: Consultancy; Celgene: Consultancy; Apopharma: Consultancy; Celgene: Consultancy; AMAG: Consultancy. Heeney:Sancilio and Company: Consultancy, Research Funding; Eli Lilly and Company: Research Funding; Pfizer: Research Funding. Ware:Global Blood Therapeutics: Consultancy; Nova Laboratories: Consultancy; Biomedomics: Research Funding; Bristol Myers Squibb: Research Funding; Addmedica: Research Funding; Bayer Pharmaceuticals: Consultancy.

Hephaestin and ceruloplasmin facilitate iron metabolism in the mouse kidney.

Multicopper ferroxidases (MCFs) play an important role in cellular iron homeostasis. However, the role of MCFs in renal metabolism remains unclear. We used Hephaestin (Heph) and Ceruloplasmin (Cp) single or double (Heph/Cp) knockout (KO) mice to study the roles of MCFs in the kidney. Renal iron levels and the expression of iron metabolism genes were examined. The non-heme iron content both in the renal cortex and medulla of Heph/Cp KO mice was significantly increased. Perls’ Prussian blue staining showed iron accumulation on the apical side of renal tubular cells in Heph/Cp KO mice. A significant increase in ferritin protein expression was also observed in the renal medulla and cortex of Heph/Cp KO mice. Both DMT1 and TfR1 protein expression were significantly decreased in the renal medulla of Heph/Cp KO mice, while the expression of DMT1 protein was significantly increased in the renal cortex of these animals. Significant increase in proteinuria and total urinary iron was observed in the double knockout mice, and this was associated with compromised structural integrity. These results suggest that KO of both the HEPH and CP genes leads to kidney iron deposition and toxicity, MCFs could protect kidney against a damage from iron excess.

Sustained treatment of sickle cell mice with haptoglobin increases HO-1 and H-ferritin expression and decreases iron deposition in the kidney without improvement in kidney function.

There is growing evidence that extracellular haemoglobin and haem mediate inflammatory and oxidative damage in sickle cell disease. Haptoglobin (Hp), the scavenger for free haemoglobin, is depleted in most patients with sickle cell disease due to chronic haemolysis. Although single infusions of Hp can ameliorate vaso-occlusion in mouse models of sickle cell disease, prior studies have not examined the therapeutic benefits of more chronic Hp dosing on sickle cell disease manifestations. In the present study, we explored the effect of Hp treatment over a 3-month period in sickle mice at two dosing regimens: the first at a moderate dose of 200mg/kg thrice weekly and the second at a higher dose of 400mg/kg thrice weekly. We found that only the higher dosing regimen resulted in increased haem-oxygenase-1 and heavy chain ferritin (H-ferritin) expression and decreased iron deposition in the kidney. Despite the decreased kidney iron deposition following Hp treatment, there was no significant improvement in kidney function. However, there was a nearly significant trend towards decreased liver infarction.

The role of S-methylisothiourea hemisulfate as inducible nitric oxide synthase inhibitor against kidney iron deposition in iron overload rats.

Background:Iron dextran is in common use to maintain iron stores. However, it is potentially toxic and may lead to iron deposition (ID) and impair functions of organs. Iron overload can regulate the expression of inducible nitric oxide synthase (iNOS) in some cells that has an important role in tissue destruction. S-methylisothiourea hemisulfate (SMT) is a direct inhibitor of iNOS, and this study was designed to investigate the effect of SMT against kidney ID in iron overload rats.Materials and Methods:24 Wistar rats (male and female) were randomly assigned to two groups. Iron overloading was performed by iron dextran 100 mg/kg/day every other day for 2 weeks. In addition, during the study, groups 1 and 2 received vehicle and SMT (10 mg/kg, ip), respectively. Finally, blood samples were obtained, and the kidneys were prepared for histopathological procedures.Results:SMT significantly reduced the serum levels of creatinine and blood urea nitrogen. However, SMT did not alter the serum levels of iron and nitrite, and the kidney tissue level of nitrite. Co-administration of SMT with iron dextran did not attenuate the ID in the kidney.Conclusion:SMT, as a specific iNOS inhibitor, could not protect the kidney from ID while it attenuated the serum levels of kidney function biomarkers.

Three Months of Human Haptoglobin Treatment Decreases Iron Deposition in the Kidneys of Townes Sickle Mice

Introduction: Haptoglobin (Hp), the scavenger for hemoglobin, and hemopexin (Hx), the scavenger for heme, are depleted in most patients with sickle cell disease due to chronic hemolysis. There is mounting evidence of the crucial role of free hemoglobin and/or free heme in mediating inflammatory and oxidative damage in sickle cell disease, including vaso-occlusion and acute chest syndrome. Purified Hp has been used in Japan for a variety of hemolytic conditions and has been proposed as a potential treatment for sickle cell disease. Although infusions of Hp or Hx have been shown to ameliorate vaso-occlusion, acute lung injury, and heme toxicity in sickle cell mouse models, no prior studies have examined the utility of chronic Hp treatment for amelioration of organ damage. We therefore studied the effect of 3 months of chronic Hp treatment in the Townes sickle mouse model.Methods: Male and female Townes mice (Stock number 013071, The Jackson Laboratory) were used for all experiments, starting at 1 or 3 months of age. SS genotype was confirmed by PCR and HPLC. Organ damage in the spleen, liver, and kidneys as previously described was confirmed. Human Hp solution was a kind gift from Bio Product Laboratory (BPL, Hertfordshire, UK). Hp or equivalent volume PBS control was administered intraperitoneally (IP) in the first cohort of 5 mice and then subcutaneously (SC) in the next two cohorts of 7 and 12 mice on a 48-72 hr dosing schedule of Monday, Wednesday, Friday for a period of 3 months. At the end of 3 months treatment, mice were evaluated by the following studies (with concurrent blinding to treatment group for most studies): plasma Hp (ELISA), plasma heme (QuantiChrom heme assay), urine osmolality (osmometer), urine albumin (ELISA), CBC (Advia 120), WBC differential (Advia 120 and manual count), red blood cell ektacyometry (ektacyometer), organ mass (percent of body weight), and organ histology.Results: Mouse Hp levels in SS Townes mice were confirmed to be markedly low compared to Townes AA mice (mean ± SD: SS 2 ± 1 versus AA 39 ± 4 ug/mL). Dose-finding experiments determined that a dose of 200-400 mg/kg IP or SC in SS mice resulted in a 24 hr peak concentration that was 5-14X supraphysiologic, variably physiologic at 48 hr, and absent or almost absent at 72 hr. Chronic dosing at the 400 mg/kg IP in SA mice showed no CBC or organ toxicity. Three successive cohorts of SS mice were treated with Hp (or equivalent volume of PBS): 200 mg/kg IP in 3-month old mice, 400 mg/kg SC in 3-month old mice, and 400 mg/kg SC in 1-month old mice. At the 400 mg/kg dosing levels, there was a significant decrease in iron deposition in the kidneys of both 4-month and 6-month old mice (treatment started at 1-month and 3 months, respectively) (Table 1). There was also a trend towards decreased liver infarction in 6-month old mice (Table 2).Discussion: Functional binding of the administered human Hp to the human Hb of the Townes mice likely occurred, as evidenced by the decrease in iron deposition in the kidneys, suggesting that formation of the complex prevents filtration of Hb into the kidneys. Surprisingly, kidney function as measured by urine osmolality or albumin excretion was not improved, which may be explained by continued heme-laden red cell microparticle filtration (Camus SM, Blood 2015). Encouragingly, however, a trend towards decreased liver infarction in older mice was observed. The less-than-expected effect of Hp on mouse disease severity may also be explained by: 1) continuous physiologic Hp concentrations not being maintained with the dosing frequency while continued hemolysis releases Hb every minute of the day, and 2) CD163-mediated uptake in mice seems to only account for a part of the Hb clearance as opposed to in humans (Etzerodt A, Antioxid Redox Signal 2013). Despite the limitations of the SCD mouse model, the current study suggests haptogobin infusions could be beneficial in SCD patients.Acknowledgment: The authors are grateful to Sandra Suzuka for performing the HPLC.Table 1Table 1. Kidney iron deposition (scale 1-10)Treatment group6-month old SS4-month old SS400 mg/kg Hp4.0 ± 1.41 ± 1.1PBS9.3 ± 0.65 ± 2.9p-value0.0020.02Table 2Liver infarction (scale 1-10)Treatment group6-month old SS4-month old SS400 mg/kg Hp2.6 ± 2.03.7 ± 2.8PBS6.3 ± 2.43.8 ± 2.3p-value0.070.91 DisclosuresBelcher:Biogen Idec: Research Funding; Seattle Genetics: Research Funding; CSL Behring: Research Funding. Vercellotti:CSL Behring: Research Funding; Seattle Genetics: Research Funding; Cydan: Research Funding; Biogen Idec: Research Funding.

Iron Overload of the Kidneys of Patients with Thalassemia and Sickle-Cell Disease: Final Results of a Prospective Study in 224 Patients Using Magnetic Resonance Imaging T2 and R2* Techniques

▪Iron overload is a significant complication of hemoglobinopathies, despite the adequate iron chelation, which is administered to patients nowadays. Recently, magnetic resonance imaging (MRI) gradient echo (T2*), the reciprocal of T2* (known as R2*) and spin echo (T2) techniques have been developed to quantify tissue iron in the liver and the heart. Patients with thalassemia or sickle-cell disease (SCD) may develop kidney impairment during the course of their disease. However, the significance of iron overload in the kidneys of these patients in the development of renal impairment is poorly understood and, according to our knowledge, it has not been evaluated in a prospective study. Thus, the aim of our study was to evaluate kidney R2* and T2 MRI as surrogates for kidney iron of patients with different hemoglobinopathies and correlate these results with markers of renal impairment, markers of hemolysis and other disease features.We prospectively studied 224 patients with hemoglobinopathies who are followed and treated in a single center: 109 had thalassemia major (TM), 58 thalassemia intermedia (TI) and 57 SCD (35% of those were double heterozygous for SC/beta-thalassemia; HbS/beta-thal). All patients had MR examinations of the kidneys, liver and heart. For T2* mapping a gradient echo, multi echo FSPGR sequence was used, while for T2 mapping a T2-prepared single shot SSFP technique with multi echoes was performed. The normal reference values of T2 in our lab was <80 msec, while for R2* normal range we used the one previously described by Schein et al (J Magn Reson Imaging 2008;28:698-704), which was 21.3±5.8 Hz with a 95% confidence upper limit of 33.7 Hz. Regarding renal function, patients were divided in the 5 chronic kidney disease (CKD) stages of the KDIGO classification, according to eGFR evaluated by the CKD-EPI formula.Kidney T2 values were (mean±SD) 109.7±12.1 msec, 101.4±12.3 msec and 100.1±11.3 msec for patients with TM, TI and SCD, respectively; 9/109 (8.2%) TM, 3/57 (5.2%) SCD and 2/58 (3.4%) TI patients had T2 values lower than the normal limit of <80 msec. Of interest, none of the HbS/beta-thal patients had T2 values lower than the normal limit. Kidney R2* values were 17.3±10.8 Hz, 21.5±15.4 Hz and 19.1±13.6, for patients with TM, TI and SCD, respectively. Compared to historic controls, 5/109 (4.5%) TM, 8/58 (13.7%) TI and 4/57 (7%) SCD patients had R2* >upper normal limit of 33.7 Hz. There was no difference between the different groups regarding T2 or R2* values.eGFR values were 102±21, 111±12 and 98±28 ml/min/1.73m2, for patients with TM, TI and SCD, respectively. Patients with TI had higher eGFR than TM and SCD patients (p=0.014 and p=0.001, respectively). Six (5.5%) patients with TM and six (10.5%) with SCD had renal impairment of CKD stage 3-5. No patient with TI presented with stage 3-5 renal impairment. There was no correlation between T2 or R2* values and eGFR or serum creatinine in all patients groups. This may be due to the different T2 or R2* values between the two kidneys of the same patient (p=0.001 and p=0.01, for T2 and R2*, respectively).Patients with low T2 values (<80 msec) had higher serum ferritin and lower Hb (p=0.001 and p=0.01, respectively). Patients with high R2* values (>33.7 Hz) had higher serum LDH and reticulocyte counts (p=0.012 and p=0.01, respectively). Renal R2* (r=-0.286, p=0.001) but not T2 values correlated also with liver T2* values. In TM patients there was a negative correlation of T2 values with ferritin (r=-0.300, p<0.01) and LDH (r=-0.340, p<0.01), a positive correlation of R2* with ferritin (r=0.4, p<0.001) and LDH (r=0.382, p<0.001) and a negative correlation with Hb (r=-0.278, p=0.01).Our study provides evidence that T2 and R2* reflects kidney iron deposition in patients with different hemoglobinopathies: from 4.5% of TM patients who regularly receive iron chelation to 13.7% of TI patients. Importantly we found differences in iron overload between the two kidneys of the same patient in all studied group; finding which needs further evaluation and examination of possible correlations with each kidney's function. In TM patients both MRI techniques correlated with serum ferritin and LDH. Further studies, possibly with the performance of renal biopsies, will reveal the best MRI technique for detecting iron overload in the kidneys of patients with hemoglobinopathies as well as their role in the development of renal impairment in some of these patients. DisclosuresVoskaridou:Celgene: Membership on an entity's Board of Directors or advisory committees, Other: travelling, Research Funding. Terpos:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel expenses; Celgene: Honoraria, Other: travel expenses; Novartis: Honoraria.

Danshen (Salvia miltiorrhiza) Injection Suppresses Kidney Injury Induced by Iron Overload in Mice

ObjectivesExcessive iron can accumulate in the kidney and induce tissue damage. Danshen (Salvia miltiorrhiza) injection is a traditional Chinese medicinal preparation used for preventing and treating chronic renal failure. The aim of the present study was to evaluate the effects of treatment with Danshen injection on iron overload-induced kidney damage.MethodsMice were mock-treated with saline (control group) or given a single dose of iron dextran without treatment (iron overload group, 50 mg/kg/day for 2 weeks) or with daily treatments of low-dose Danshen (3 g/kg/day), high-dose Danshen (6 g/kg/day) or deferoxamine (100 mg/kg/day).ResultsTreatment of iron-overloaded mice with Danshen injection led to significant improvements of body weight and decreased iron levels in the kidney. Danshen injection treatment also reduced concentrations of blood urea nitrogen, creatinine and malondialdehyde and enhanced glutathione peroxidase and superoxide dismutase activities. Histopathological examinations showed that Danshen injection ameliorated pathological changes and reduced iron deposition in kidneys of iron overloaded mice. Furthermore, the treatment was demonstrated to suppress apoptosis in nephrocytes.ConclusionsThese results indicated that Danshen injection exerted significant renal protective effects in iron-overloaded mice, which were closely associated with the decrease of iron deposition and suppression of lipid peroxidation and apoptosis in the kidney.

Study of Renal Iron Overload by T2* MRI in a Large Cohort of Thalassemia Major Patients

AbstractAbstract 5177 Background.Renal dysfunction has been reported in adult subjects with thalassemia major (TM) since 1975. One of the main cause is the iron overload consequent to regular transfusions. Multiecho T2* MRI is a well-established technique for cardiac and hepatic iron overload assessment, but there very few report concerning the kidneys.The aims of this study were to describe the T2* values of the kidneys in patients with TM, to investigate the correlation between renal and myocardial or hepatic siderosis and biventricular cardiac function. Methods.119 TM patients (58 men, 30. 7 ± 8. 2 years) enrolled in the Myocardial Iron Overload (MIOT) networks underwent MRI. For the measurement of iron overload, multiecho T2* sequences were used. The left ventricle was segmented into a 16-segments standardized model and the T2* value on each segment was calculated as well as the global value. In the liver, the T2* value was assessed in a single region of interest (ROI) in a homogeneous area of the parenchyma. For each kidney, T2* values were calculated in three different ROIs and were averaged to obtain a representative value for the kidney. The mean T2* value over the kidneys was also calculated. Cine images were obtained to quantify biventricular morphological and functional parameters in a standard way. Results.T2* values in the right kidney were significant lower than in the left kidney (40. 3±11. 9 ms vs 44. 1±12. 7 ms, P<0. 0001). The mean T2* value over the kidneys was 42. 2±11. 9 ms and 40 patients (33. 6%) had a pathological value (T2*<36 ms, lower limit of normal evaluated on 20 healthy subjects). The mean T2* value did not show a significant difference amongst men ad women (43. 2±11. 7 ms versus 41. 3±12. 1 ms, P=0. 378). The mean T2* values increased with age in a significant manner (r=0. 321, P<0. 0001). There was a significant negative correlation between serum ferritin levels and mean renal T2* values (r=-0. 446, P<0. 0001). Significant positive correlations of the mean T2* values were demonstrated for liver (r=0. 511, P<0. 0001) and global heart (r=0. 262, P=0. 004) T2* values (Figure 1). No correlation was found between renal iron overload and bi-ventricular function parameters. Conclusions.Systemic T2* differences between left and right kidneys were found, with significant lower values in the right one. Mean T2* value increased with age. We confirmed that kidney iron deposition was not very common in TM, but it was correlated with iron deposition in liver and heart. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Lysosomal degradation of the carboxydextran shell of coated superparamagnetic iron oxide nanoparticles and the fate of professional phagocytes

Contrast agents based on dextran-coated superparamagnetic iron oxide nanoparticles (SPIO) are internalized by professional phagocytes such as hepatic Kupffer cells, yet their role in phagocyte biology remains largely unknown. Here we investigated the effects of the SPIO ferucarbotran on murine Kupffer cells and human macrophages. Intravenous injection of ferucarbotran into mice led to rapid accumulation of the particles in phagocytes and to long-lasting increased iron deposition in liver and kidneys. Macrophages incorporate ferucarbotran in lysosomal vesicles containing α-glucosidase, which is capable of degrading the carboxydextran shell of the ferucarbotran particles. Intravenous injection of ferucarbotran into mice followed by incorporation of the nanoparticles into Kupffer cells triggered apoptosis and the subsequent depletion of Kupffer cells. In macrophages, the proinflammatory cytokine TNF-α increased the apoptosis rate, the reactive oxygen species production and the activation of c-Jun N-terminal kinase elicited by ferucarbotran, which might be mediated by the induction of cytoplasmic phospholipase A2 by TNF-α. Notably, the nanoparticle-induced apoptosis of murine Kupffer cells could be prevented by treatment of the mice with the radical scavenger edaravone. Thus, nanosized carboxydextran-coated SPIO-based contrast agents are retained for extended time periods by liver macrophages, where they elicit delayed cell death, which can be antagonized by a therapeutic radical scavenger.

Magnetic resonance detection of kidney iron deposition in sickle cell disease: A marker of chronic hemolysis

To study the pattern, etiology, and significance of renal iron accumulation in chronically transfused sickle cell disease (SCD) and thalassemia major (TM) patients using magnetic resonance imaging (MRI). Magnetic resonance imaging (MRI) was performed in 75 SCD patients, 73 TM patients, and 16 healthy controls. Multiecho gradient echo protocols were used to measure T2* reciprocals (R2*) in the kidney, liver, and heart. Kidney R2* was compared to tissue iron estimates, serum iron markers, and surrogates of intravascular hemolysis by univariate regression. Mean R2* in SCD patients was 55.3+/-45.3 Hz, compared with 22.1+/-11 Hz in TM patients and 21.3+/-5.8 Hz in control subjects (P<0.001). Kidney R2* decreased with advancing age (R2=0.09, P<0.02). Kidney R2* correlated strongly with increased serum lactate dehydrogenase levels found in SCD (R2=0.55, P<0.001), but was independent of hepatic iron concentration and cardiac R2*. Kidney R2* did not correlate with blood pressure, creatinine, cardiac index, or right and left ejection fraction. Intravascular hemolysis, not chronic transfusion, causes renal hemosiderosis in SCD. Prospective trials are necessary to determine whether kidney R2* is a biomarker for hemolysis-mediated vascular complications in SCD.

Effect of melatonin, curcumin, quercetin, and resveratrol on acute ferric nitrilotriacetate (Fe-NTA)-induced renal oxidative damage in rats

The influence of melatonin, curcumin, quercetin, and resveratrol pretreatment on ferric nitrilotriacetate (Fe-NTA)-induced oxidative renal damage was studied. Male Wistar rats were treated orally once daily for 3 days with melatonin (10 mg/kg), curcumin (50 mg/kg), quercetin (15 mg/kg), and resveratrol (10 mg/kg). One hour after the last dose of antioxidants, a single dose of Fe-NTA was administered (8 mg of Fe/kg body weight, i.p.) to pre-treated animals. Twenty-four hours after Fe-NTA administration, the lipid peroxidation (LP), reduced glutathione (GSH), catalase (CAT), and glutathione peroxidase (GSH-Px) were estimated in kidney homogenates. Iron, zinc, and copper concentrations were estimated in kidney tissue. Administration of Fe-NTA to rats induced renal LP (170%, P < 0.001) and inhibited catalase (78%, P < 0.05) in the kidney. The oral pretreatment with melatonin, curcumin, quercetin, and resveratrol each one was effective in decreasing the Fe-NTA-induced LP (P < 0.001); however, it did not influence the FeNTA-induced inhibition of renal CAT activity. No changes were found in renal GSH level and GSH-Px activity compared to control animals. The pretreatment with antioxidants did not affect the increase in renal iron content, blood urea nitrogen/creatinine ratio, and relative kidney weight of FeNTA-intoxicated rats. The results indicate that the pretreatment with natural antioxidants, curcumin, melatonin, quercetin, and resveratrol, significantly and equally suppressed lipid peroxidation induced by Fe-NTA but had no effect on other markers of FeNTA nephrotoxicity and iron deposition in kidneys.

Abnormal Iron Deposition in Renal Cells in the Rat with Chronic Angiotensin II Administration

Acute experimental iron loading causes iron to accumulate in the renal tissue. The accumulation of iron may play a role in enhancing oxidant-induced tubular injury by producing increased amounts of reactive oxygen species. From findings in cells from heme oxygenase-1 (HO-1)-deficient mice, HO-1 is postulated to prevent abnormal intracellular iron accumulation. Recently, it has been reported that HO-1 is induced in the renal tubular epithelial cells, in which iron is deposited after iron loading, and that this HO-1 induction may be involved in ameliorating iron-induced renal toxicity. We previously showed that chronic administration of angiotensin II to rats induces HO-1 expression in the tubular epithelial cells. These observations led us to investigate whether there is a link between iron deposition and HO-1 induction in renal tubular cells in rats undergoing angiotensin II infusion. In the present study, rats were given angiotensin II for continuously 7 days. Prussian blue staining revealed the distinct deposits of iron in the proximal tubular epithelial cells after angiotensin II administration. Electron microscopy demonstrated that iron particles were present in the lysosomes of these cells. Histologic and immunohistochemical analyses showed that stainable iron and immunoreactive ferritin and HO-1 were colocalized in the tubular epithelial cells. Treatment of angiotensin II-infused rats with an iron chelator, deferoxamine, blocked the abnormal iron deposition in kidneys and also the induced expression of HO-1 and ferritin expression. Furthermore, deferoxamine treatment suppressed the angiotensin II-induced increase in the urinary excretion of protein and N-acetyl-β-d-glucosaminidase, a marker of tubular injury; however, deferoxamine did not affect the angiotensin II-induced decrease in glomerular filtration rate. These results suggest that angiotensin II causes renal injury, in part, by inducing the deposition of iron in the kidney.