Iron Chelation Suppresses Ferritin Upregulation and Attenuates Vascular Dysfunction in the Aorta of Angiotensin II–Infused Rats

M2 Macrophage Membrane-Camouflaged Fe3 O4 -Cy7 Nanoparticles with Reduced Immunogenicity for Targeted NIR/MR Imaging of Atherosclerosis

Atherosclerosis （AS） is the primary reason behind cardiovascular diseases, leading to approximately one-third of global deaths. Developing a novel multi-model probe to detect AS is urgently required. Macrophages are the primary cells from which AS genesis occurs. Utilizing natural macrophage membranes coated on the surface of nanoparticles is an efficient delivery method to target plaque sites. Herein, Fe3 O4 -Cy7 nanoparticles (Fe3 O4 -Cy7 NPs), functionalized using an M2 macrophage membrane and a liposome extruder for Near-infrared fluorescence and Magnetic resonance imaging, are synthesized. These macrophage membrane-coated nanoparticles (Fe3 O4 @M2 NPs) enhance the recognition and uptake using active macrophages. Moreover, they inhibit uptake using inactive macrophages and human coronary artery endothelial cells. The macrophage membrane-coated nanoparticles (Fe3 O4 @M0 NPs, Fe3 O4 @M1 NPs, Fe3 O4 @M2 NPs) can target specific sites depending on the macrophage membrane type and are related to C-C chemofactor receptor type 2 protein content. Moreover, Fe3 O4 @M2 NPs demonstrate excellent biosafety in vivo after injection, showing a significantly higher Fe concentration in the blood than Fe3 O4 -Cy7 NPs. Therefore, Fe3 O4 @M2 NPs effectively retain the physicochemical properties of nanoparticles and depict reduced immunological response in blood circulation. These NPs mainly reveal enhanced targeting imaging capability for atherosclerotic plaque lesions.

H2S regulation of iron homeostasis by IRP1 improves vascular smooth muscle cell functions

Either H2S or iron is essential for cellular processes. Abnormal metabolism of H2S and iron has increased risk for cardiovascular diseases. The aim of the present study is to examine the mutual interplay of iron and H2S signals in regulation of vascular smooth muscle cell (SMC) functions. Here we found that deficiency of cystathionine gamma-lyase (CSE, a major H2S-producing enzyme in vascular system) induced but NaHS (a H2S donor) administration attenuated iron accumulation in aortic tissues from angiotensin II-infused mice. In vitro, iron overload induced labile iron levels, promoted cell proliferation, disrupted F-actin filaments, and inhibited protein expressions of SMC-specific markers (αSMA and calponin) more significantly in SMCs from CSE knockout mice (KO-SMCs) than the cells from wild-type mice (WT-SMCs), which could be reversed by exogenously applied NaHS. In contrast, KO-SMCs were more vulnerable to iron starvation-induced cell death. Either iron overload or NaHS did not affect elastin level and gelatinolytic activity. We further found that H2S induced more aconitase activity of iron regulatory protein 1 (IRP1) but inhibited its RNA binding activity accompanied with increased protein levels of ferritin and ferriportin, which would contribute to the lower level of labile iron level inside the cells. In addition, iron was able to suppress CSE-derived H2S generation, while iron also non-enzymatically induced H2S release from cysteine. This study reveals the mutual interaction between iron and H2S signals in regulating SMC phenotypes and functions; CSE/H2S system would be a target for preventing iron metabolic disorder-related vascular diseases.

Iron metabolism and cardiovascular disease: Basic to translational purviews and therapeutical approach

Iron interactions with the cardiovascular system were proposed about half a century ago, yet a clear-cut understanding of this micronutrient and its intricacies with acute and chronic events is still lacking. In chronic heart failure, patients with decreased iron stores appear to benefit from intravenous administration of metallic formulations, whereas acute diseases (e.g., myocardial infarction, stroke) are barely studied in randomized controlled trials in humans. However, proof-of-concept studies have indicated that the dual redox characteristics of iron could be involved in atherosclerosis, necrosis, and ferroptosis. To this end, we sought to review the currently available body of literature pertaining to these temporal profiles of heart diseases, as well as the pathophysiologic mechanism by which iron enacts, underlining key points related to treatment options.

Iron overload, oxidative stress and vascular dysfunction: Evidences from clinical studies and animal models

Although iron is a metal involved in many in vital processes due to its redox capacity, body iron overloads lead to tissue damage, including the cardiovascular system. While cardiomyopathy was the focus since the 1960s, the impact on the vasculature was comparatively neglected for about 40 years, when clinical studies correlating iron overload, oxidative stress, endothelial dysfunction, arterial stiffness and atherosclerosis reinforced an "iron hypothesis". Due to controversial results from some epidemiological studies investigating atherosclerotic events and iron levels, well-controlled trials and animal studies provided essential data about the influence of iron, per se, on the vasculature. As a result, the pathophysiology of vascular dysfunction in iron overload have been revisited. This review summarizes the knowledge obtained from epidemiological studies, animal models and "in vitro" cellular systems in recent decades, highlighting a more harmful than innocent role of iron excess for the vascular homeostasis, which supports our proposal to hereafter denominate "iron overload vasculopathy". Additionally, evidence-based therapeutic targets are pointed out to be tested in pre-clinical research that may be useful in cardiovascular protection for patients with iron overload syndromes.

Non-Transferrin-Bound Iron in the Spotlight: Novel Mechanistic Insights into the Vasculotoxic and Atherosclerotic Effect of Iron

Significance: While atherosclerosis is an almost inevitable consequence of aging, food preferences, lack of exercise, and other aspects of the lifestyle in many countries, the identification of new risk factors is of increasing importance to tackle a disease, which has become a major health burden for billions of people. Iron has long been suspected to promote the development of atherosclerosis, but data have been conflicting, and the contribution of iron is still debated controversially. Recent Advances: Several experimental and clinical studies have been recently published about this longstanding controversial problem, highlighting the critical need to unravel the complexity behind this topic. Critical Issues: The aim of the current review is to provide an overview of the current knowledge about the proatherosclerotic impact of iron, and discuss the emerging role of non-transferrin-bound iron (NTBI) as driver of vasculotoxicity and atherosclerosis. Finally, I will provide detailed mechanistic insights on the cellular processes and molecular pathways underlying iron-exacerbated atherosclerosis. Overall, this review highlights a complex framework where NTBI acts at multiple levels in atherosclerosis by altering the serum and vascular microenvironment in a proatherogenic and proinflammatory manner, affecting the functionality and survival of vascular cells, promoting foam cell formation and inducing angiogenesis, calcification, and plaque destabilization. Future Directions: The use of additional iron markers (e.g., NTBI) may help adequately predict predisposition to cardiovascular disease. Clinical studies are needed in the aging population to address the atherogenic role of iron fluctuations within physiological limits and the therapeutic value of iron restriction approaches. Antioxid. Redox Signal. 35, 387-414.

Iron chelation suppresses secondary bleeding after intracerebral hemorrhage in angiotensin II-infused mice

AIMS

Secondary bleeding and further hematoma expansion (HE) aggravate brain injury after intracerebral hemorrhage (ICH). The majority of HE results from hypertensive ICH. Previous study reported higher iron content in the brains of hypertensive patients. Iron overload exacerbates the risk of hemorrhagic transformation in thromboembolic stroke mice. Whether iron overload during the process of hypertension participates in secondary bleeding of hypertensive ICH remains unclear.

METHODS

Hypertension was induced by continuous infusion of angiotensin II (Ang II) with an osmotic pump into C57BL/6 mice. ICH was simulated by intrastriatal injection of the liquid polymer Onyx-18. Iron chelation and iron overload was achieved by deferoxamine mesylate or iron dextran injection. Secondary bleeding was quantified by measuring the hemoglobin content in the ipsilateral brain hemisphere.

RESULTS

Ang II-induced hypertensive mice showed increased iron accumulation in the brain and expanded secondary hemorrhage after ICH modeling. Moreover, iron chelation suppressed while iron overload aggravated secondary bleeding. Mechanistically, iron exacerbated the loss of contractile cerebral vascular smooth muscle cells (VSMCs), aggravated blood-brain barrier (BBB) leakage in Ang II-induced hypertensive mice, and increased glial and MMP9 accumulation after ICH.

CONCLUSION

Iron overload plays a key role in secondary bleeding after ICH in Ang II-induced hypertensive mice. Iron chelation during the process of Ang II-induced hypertension suppresses secondary bleeding after ICH.

Are losartan and imatinib effective against SARS-CoV2 pathogenesis? A pathophysiologic-based in silico study

Proposing a theory about the pathophysiology of cytokine storm in COVID19, we were to find the potential drugs to treat this disease and to find any effect of these drugs on the virus infectivity through an in silico study. COVID-19-induced ARDS is linked to a cytokine storm phenomenon not explainable solely by the virus infectivity. Knowing that ACE2, the hydrolyzing enzyme of AngII and SARS-CoV2 receptor, downregulates when the virus enters the host cells, we hypothesize that hyperacute AngII upregulation is the eliciting factor of this ARDS. We were to validate this theory through reviewing previous studies to figure out the role of overzealous activation of AT1R in ARDS. According to this theory losartan may attenuate ARDS in this disease. Imatinib, has previously been elucidated to be promising in modulating lung inflammatory reactions and virus infectivity in SARS and MERS. We did an in silico study to uncover any probable other unconsidered inhibitory effects of losartan and imatinib against SARS-CoV2 pathogenesis. Reviewing the literature, we could find that over-activation of AT1R could explain precisely the mechanism of cytokine storm in COVID19. Our in silico study revealed that losartan and imatinib could probably: (1) decline SARS-CoV2 affinity to ACE2. (2) inhibit the main protease and furin, (3) disturb papain-like protease and p38MAPK functions. Our reviewing on renin-angiotensin system showed that overzealous activation of AT1R by hyper-acute excess of AngII due to acute downregulation of ACE2 by SARS-CoV2 explains precisely the mechanism of cytokine storm in COVID-19. Besides, based on our in silico study we concluded that losartan and imatinib are promising in COVID19.

Innate-adaptive immunity interplay and redox regulation in immune response

Innate and adaptive immune cell activation and infiltration is the key characteristic of tissue inflammation. The innate immune system is the front line of host defense in which innate immune cells are activated by danger signals, including pathogen- and danger-associated molecular pattern, and metabolite-associated danger signal. Innate immunity activation can directly contribute to tissue inflammation or immune resolution by phagocytosis and secretion of biologically active molecules, or indirectly via antigen-presenting cell (APC) activation-mediated adaptive immune responses. This review article describes the cellular and molecular interplay of innate-adaptive immune systems. Three major mechanisms are emphasized in this article for their role in facilitating innate-adaptive immunity interplay. 1) APC can be formed from classical and conditional innate immune cells to bridge innate-adaptive immune response. 2) Immune checkpoint molecular pairs connect innate and adaptive immune cells to direct one-way and two-way immune checkpoint reactions. 3) Metabolic reprogramming during immune responses leads to excessive cytosolic and mitochondrial reactive oxygen species (ROS) production. Increased NADPH oxidase-derived extracellular and intracellular ROS are mostly responsible for oxidative stress, which contributes to functional changes in immune cells. Further understanding of innate-adaptive immunity interplay and its underlying molecular basis would lead to the identification of therapeutic targets for immunological and inflammatory disease.

Influence of mitochondrial and systemic iron levels in heart failure pathology

Iron deficiency or overload poses an increasingly complex issue in cardiovascular disease, especially heart failure. The potential benefits and side effects of iron supplementation are still a matter of concern, even though current guidelines suggest therapeutic management of iron deficiency. In this review, we sought to examine the iron metabolism and to identify the rationale behind iron supplementation and iron chelation. Cardiovascular disease is increasingly linked with iron dysmetabolism, with an increased proportion of heart failure patients being affected by decreased plasma iron levels and in turn, by the decreased quality of life. Multiple studies have concluded on a benefit of iron administration, even if just for symptomatic relief. However, new studies field evidence for negative effects of dysregulated non-bound iron and its reactive oxygen species production, with concern to heart diseases. The molecular targets of iron usage, such as the mitochondria, are prone to deleterious effects of the polyvalent metal, added by the scarcely described processes of iron elimination. Iron supplementation and iron chelation show promise of therapeutic benefit in heart failure, with the extent and mechanisms of both prospects not being entirely understood. It may be that a state of decreased systemic and increased mitochondrial iron levels proves to be a useful frame for future advancements in understanding the interconnection of heart failure and iron metabolism.

JNK/p66Shc/ITCH Signaling Pathway Mediates Angiotensin II-induced Ferritin Degradation and Labile Iron Pool Increase

Angiotensin II (Ang II) induces deleterious changes in cellular iron metabolism and increases the generation of reactive oxygen species. This leads to an impairment of neuronal and vascular function. However, the mechanism underpinning Ang II-induced changes in iron metabolism is not known. We hypothesized that Ang II-induced ferritin degradation and an increase in the labile iron pool are mediated by the c-Jun N-terminal kinase (JNK)/p66Shc/ITCH signaling pathway. We show that Ang II treatment induced ferritin degradation in an endothelial cell lines derived from the bovine stem pulmonary artery (CPAE), human umbilical vein endothelial cells (HUVEC), and HT22 neuronal cells. Ferritin degradation was accompanied by an increase in the labile iron pool, as determined by changes in calcein fluorescence. The JNK inhibitor SP600125 abolished Ang II-induced ferritin degradation. Furthermore, the effect of Ang II on ferritin levels was completely abolished in cells transfected with vectors encoding catalytically inactive variants of JNK1 or JNK2. CPAE cells expressing inactive ITCHor p66Shc (substrates of JNK kinases) were completely resistant to Ang II-induced ferritin degradation. These observations suggest that Ang II-induced ferritin degradation and, hence, elevation of the levels of highly reactive iron, are mediated by the JNK/p66Shc/ITCH signaling pathway.

Blockade of angiotensin AT1 receptors prevents arterial remodelling and stiffening in iron-overloaded rats

BACKGROUND AND PURPOSE

Damage to the vasculature caused by chronic iron-overload in both humans and animal models, is characterized by endothelial dysfunction and reduced compliance. In vitro, blockade of the angiotensin II AT₁ receptors reversed functional vascular changes induced by chronic iron-overload. In this study, the effect of chronic AT₁ receptor blockade on aorta stiffening was assessed in iron-overloaded rats.

EXPERIMENTAL APPROACH

Male Wistar rats were treated for 15 days with saline as control group, iron dextran 200 mg·kg^-1 ·day^-1 , 5 days a week (iron-overload group), losartan (20 mg·kg^-1 ·day^-1 in drinking water), and iron dextran plus losartan. Mechanical properties of the aorta were assessed in vivo. In vitro, aortic geometry and biochemical composition were assessed with morphometric and histological methods.

KEY RESULTS

Thoracoabdominal aortic pulse wave velocity (PWV) increased significantly, indicating a decrease in aortic compliance. Co-treatment with losartan prevented changes on PWV, β-index, and elastic modulus in iron-overloaded rats. This iron-related increase in PWV was not related to changes in aortic geometry and wall stress. but to increased elastic modulus/wall stress ratio, suggesting that a change in the composition of the wall was responsible for the stiffness. Losartan treatment also ameliorated the increase in aorta collagen content of the iron-overload group, without affecting circulating iron or vascular deposits.

CONCLUSIONS AND IMPLICATIONS

Losartan prevented the structural and functional indices of aortic stiffness in iron-overloaded rats, implying that inhibition of the renin-angiotensin system would limit the vascular remodelling in chronic iron-overload.

Angiotensin II down-regulates transferrin receptor 1 and ferroportin 1 expression in Neuro-2a cells via activation of type-1 receptor

Angiotensin II (ANGII) modulates expression of iron intake and export proteins in cultured neurons. However, the relevant mechanisms have not been fully elucidated. Here, we investigated the effects of ANGII and/or candesartan, a ANGII-Type-1 Receptor (AT1R) antagonist, and PD123319, a ANGII-Type-2 Receptor (AT2R) antagonist on expression of transferrin receptor 1 (TfR1), ferroportin 1 (Fpn1)and ferritin as well as iron regulatory proteins (IRPs), hepcidin and nuclear factor E2-related factor 2 (Nrf2) in Neuro-2a cells. We demonstrated that ANGII induces a significant reduction in expression of TfR1, Fpn1, IRP2 proteins and Nrf2 mRNA and an increase in ferritin protein and hepcidin mRNA, while candesartan, but not PD123319, significantly attenuated or reversed all these ANGII-induced changes in Neuro-2a cells. These findings imply that ANGII down-regulates TfR1 expression likely via the AT1R/IRP2 pathway, and Fpn1 expression via ATR1/hepcidin and AT1R/ Nrf2 pathways.

Renal iron accelerates the progression of diabetic nephropathy in the HFE gene knockout mouse model of iron overload

Diabetic nephropathy (DN) is the most common cause of end-stage renal disease associated with high mortality worldwide. Increases in iron levels have been reported in diabetic rat kidneys as well as in human urine of patients with diabetes. In addition, a low-iron diet or iron chelators delay the progression of DN in patients with diabetes and in animal models of diabetes. Possible maladaptive mechanisms of organ damage by tissue iron accumulation have not been well studied. We recently reported that iron induced the retinal renin-angiotensin system (RAS) and accelerated the progression of diabetic retinopathy. However, whether iron regulates the systemic RAS is unknown. To explore if iron alters the expression of intrarenal RAS and its role in the progression of DN, we used the high Fe iron (HFE) knockout mouse, a genetic model of systemic iron overload. We found that diabetes upregulated the expression of iron regulatory proteins and augmented tissue iron accumulation in the kidneys of both type 1 and type 2 diabetic mouse models. Iron accumulation in the kidneys of HFE knockout mice was associated with increase in serum and intrarenal renin expression. Induction of diabetes in HFE knockout mice using streptozotocin caused a much higher accumulation of renal iron and accelerated the progression of nephropathy compared with diabetic wild-type mice. Treatment of diabetic mice with the iron chelator deferiprone reversed the renin upregulation and reduced kidney injury. Thus, our results establish a new link between renal iron and RAS activity. Exploring the mechanisms of iron-induced RAS activation further may have a significant therapeutic impact on hypertension and DN.

Effects of iron chelating agent on Schistosoma mansoni infected murine model

Schistosomiasis is one of the major health problems in many tropical and developing countries. Infection takes place once cerceriae penetrate human skin, then it changed into schistosomules. The schistosomules takes iron in the form of heme from host's haemoglobin, ferritin and transferrin. Iron is a vital element not only for growth and sexual maturity of schistosomules to adults but also for oogenesis. Since the trapped eggs are the pathological causative agent for most of pathogenesis and complications, the current work was designed to study the effects of early deprivation of schistosomules from iron in the host (in vivo) by chelating it with deferoxamine (DFO). The iron chelation has effects on growth, maturity and egg deposition, as well as it has ameliorative effects on liver pathology such as hepatic fibrosis. Mice were classified into four groups, normal control, DFO treated only, Schistosoma mansoni (S. mansoni) infected DFO untreated and S. mansoni infected DFO treated. The infected DFO treated mice showed significant reduction in fecal egg excretion with increased percentage of dead eggs and this was accompanied with a significant reduction of both total worm burden and hepatic egg load and increased dead egg percentage compared to the infected DFO untreated group. There was also a significant reduction in both serum and hepatic tissue ferritin concentrations in the infected DFO treated mice in comparison to the infected DFO untreated group. Additionally, a significant decrease in number and size of granulomas with subsequent improvement of liver fibrosis was recorded in the infected DFO treated group. This immunopathology was also associated with significant up regulation of Interlukine12 (IL12), Interferon gamma (IFN γ) and significant down regulation in interleukin4 (IL4), interleukin10 (IL10) in both serum and hepatic tissue in the infected DFO treated compared to other groups. Entirely, DFO succeeded in diminishing the growth, maturity and fecundity of S. mansoni with a subsequent improvement of hepatic pathology. As a result of the above findings, it can be concluded that DFO could be considered as a useful treatment against schistosomal infection.

HMOX1 as a marker of iron excess-induced adipose tissue dysfunction, affecting glucose uptake and respiratory capacity in human adipocytes

AIMS/HYPOTHESIS

Iron excess in adipose tissue is known to promote adipose tissue dysfunction. Here, we aimed to investigate the possible role of haem oxygenase 1 (HMOX1) in iron excess-induced adipose tissue dysfunction.

METHODS

Cross-sectionally, HMOX1 gene expression in subcutaneous and visceral adipose tissue was analysed in two independent cohorts (n = 234 and 40) in relation to obesity. We also evaluated the impact of weight loss (n = 21), weight gain (in rats, n = 20) on HMOX1 mRNA; HMOX1 mRNA levels during human adipocyte differentiation; the effects of inflammation and iron on adipocyte HMOX1; and the effects of HMOX1-induced activity on adipocyte mitochondrial respiratory function, glucose uptake and adipogenesis.

RESULTS

Adipose tissue HMOX1 was increased in obese participants (p = 0.01) and positively associated with obesity-related metabolic disturbances, and markers of iron accumulation, inflammation and oxidative stress (p < 0.01). HMOX1 was negatively correlated with mRNAs related to mitochondrial biogenesis, the insulin signalling pathway and adipogenesis (p < 0.01). These associations were replicated in an independent cohort. Bariatric surgery-induced weight loss led to reduced HMOX1 (0.024 ± 0.010 vs 0.010 ± 0.004 RU, p < 0.0001), whereas in rats, high-fat diet-induced weight gain resulted in increased Hmox1 mRNA levels (0.22 ± 0.15 vs 0.54 ± 0.22 RU, p = 0.005). These changes were in parallel with changes in BMI and adipose tissue markers of iron excess, adipogenesis and inflammation. In human adipocytes, iron excess and inflammation led to increased HMOX1 mRNA levels. HMOX1 induction (by haem arginate [hemin] administration), resulted in a significant reduction of mitochondrial respiratory capacity (including basal respiration and spare respiratory capacity), glucose uptake and adipogenesis in parallel with increased expression of inflammatory- and iron excess-related genes.

CONCLUSIONS/INTERPRETATION

HMOX1 is an important marker of iron excess-induced adipose tissue dysfunction and metabolic disturbances in human obesity.

Iron-induced skeletal muscle atrophy involves an Akt-forkhead box O3-E3 ubiquitin ligase-dependent pathway

Skeletal muscle wasting or sarcopenia is a critical health problem. Skeletal muscle atrophy is induced by an excess of iron, which is an essential trace metal for all living organisms. Excessive amounts of iron catalyze the formation of highly toxic hydroxyl radicals via the Fenton reaction. However, the molecular mechanism of iron-induced skeletal muscle atrophy has remained unclear. In this study, 8-weeks-old C57BL6/J mice were divided into 2 groups: vehicle-treated group and the iron-injected group (10 mg iron day(-1)mouse(-1)) during 2 weeks. Mice in the iron-injected group showed an increase in the iron content of the skeletal muscle and serum and ferritin levels in the muscle, along with reduced skeletal muscle mass. The skeletal muscle showed elevated mRNA expression of the muscle atrophy-related E3 ubiquitin ligases, atrogin-1 and muscle ring finger-1(MuRF1), on days 7 and 14 of iron treatment. Moreover, iron-treated mice showed reduced phosphorylation of Akt and forkhead box O3 (FOXO3a) in skeletal muscles. Inhibition of FOXO3a using siRNA in vitro in C2C12 myotube cells inhibited iron-induced upregulation of atrogin-1 and MuRF1 and reversed the reduction in myotube diameters. Iron-load caused oxidative stress, and an oxidative stress inhibitor abrogated iron-induced muscle atrophy by reactivating the Akt-FOXO3a pathway. Iron-induced skeletal muscle atrophy is suggested to involve the E3 ubiquitin ligase mediated by the reduction of Akt-FOXO3a signaling by oxidative stress.

The utility of iron chelators in the management of inflammatory disorders

Since iron can contribute to detrimental radical generating processes through the Fenton and Haber-Weiss reactions, it seems to be a reasonable approach to modulate iron-related pathways in inflammation. In the human organism a counterregulatory reduction in iron availability is observed during inflammatory diseases. Under pathological conditions with reduced or increased baseline iron levels different consequences regarding protection or susceptibility to inflammation have to be considered. Given the role of iron in development of inflammatory diseases, pharmaceutical agents targeting this pathway promise to improve the clinical outcome. The objective of this review is to highlight the mechanisms of iron regulation and iron chelation, and to demonstrate the potential impact of this strategy in the management of several acute and chronic inflammatory diseases, including cancer.

Angiotensin II inhibits uptake of transferrin-bound iron but not non-transferrin-bound iron by cultured astrocytes

The existence of all components of the renin-angiotensin system (RAS) and the iron metabolism system, and the recent findings on the functions of angiotensin II (ANGII) in peripheral iron metabolism imply that ANGII might play a role in iron homeostasis by regulating expression of iron transport proteins in the brain. Here, we investigated effects of ANGII on uptake and release of iron as well as expression of cell iron transport proteins in cultured astrocytes. We demonstrated that ANGII could significantly inhibit transferrin-bound iron (Tf-Fe) uptake and iron release as well as the expression of transferrin receptor 1 (TfR1) and the iron exporter ferroportin 1 (Fpn1) in cultured astrocytes. This indicated that the inhibitory role of ANGII on Tf-Fe uptake and iron release is mediated by its negative effect on the expression of TfR1 and Fpn1. We also provided evidence that ANGII had no effect on divalent metal transporter 1 (DMT1) expression as well as non-transferrin-bound iron (NTBI) uptake in the cells. Our findings showed that ANGII has a role to affect expression of iron transport proteins in astrocytes in vitro and also suggested that ANGII might have a physiological function in brain iron homeostasis.

Atherogenesis and iron: from epidemiology to cellular level

Iron accumulates in human atherosclerotic lesions but whether it is a cause or simply a downstream consequence of the atheroma formation has been an open question for decades. According to the so called "iron hypothesis," iron is believed to be detrimental for the cardiovascular system, thus promoting atherosclerosis development and progression. Iron, in its catalytically active form, can participate in the generation of reactive oxygen species and induce lipid-peroxidation, triggering endothelial activation, smooth muscle cell proliferation and macrophage activation; all of these processes are considered to be proatherogenic. On the other hand, the observation that hemochromatotic patients, affected by life-long iron overload, do not show any increased incidence of atherosclerosis is perceived as the most convincing evidence against the "iron hypothesis." Epidemiological studies and data from animal models provided conflicting evidences about the role of iron in atherogenesis. Therefore, more careful studies are needed in which issues like the source and the compartmentalization of iron will be addressed. This review article summarizes what we have learnt about iron and atherosclerosis from epidemiological studies, animal models and cellular systems and highlights the rather contributory than innocent role of iron in atherogenesis.

Angiotensin II inhibits iron uptake and release in cultured neurons

Based on the well-confirmed roles of angiotensin II (ANGII) in iron transport of peripheral organs and cells, the causative link of excess brain iron with and the involvement of ANGII in neurodegenerative disorders, we speculated that ANGII might also have an effect on expression of iron transport proteins in the brain. In the present study, we investigated effects of ANGII on iron uptake and release using the radio-isotope methods as well as expression of cell iron transport proteins by Western blot analysis in cultured neurons. Our findings demonstrated for the first time that ANGII significantly reduced transferrin-bound iron and non-transferrin bound iron uptake and iron release as well as expression of two major iron uptake proteins transferrin receptor 1 and divalent metal transporter 1 and the key iron exporter ferroportin 1 in cultured neurons. The findings suggested that endogenous ANGII might have a physiological significance in brain iron metabolism.

Iron chelation by deferoxamine prevents renal interstitial fibrosis in mice with unilateral ureteral obstruction

Renal fibrosis plays an important role in the onset and progression of chronic kidney diseases (CKD). Although several mechanisms underlying renal fibrosis and candidate drugs for its treatment have been identified, the effect of iron chelator on renal fibrosis remains unclear. In the present study, we examined the effect of an iron chelator, deferoxamine (DFO), on renal fibrosis in mice with surgically induced unilateral ureter obstruction (UUO). Mice were divided into 4 groups: UUO with vehicle, UUO with DFO, sham with vehicle, and sham with DFO. One week after surgery, augmented renal tubulointerstitial fibrosis and the expression of collagen I, III, and IV increased in mice with UUO; these changes were suppressed by DFO treatment. Similarly, UUO-induced macrophage infiltration of renal interstitial tubules was reduced in UUO mice treated with DFO. UUO-induced expression of inflammatory cytokines and extracellular matrix proteins was abrogated by DFO treatment. DFO inhibited the activation of the transforming growth factor-β1 (TGF-β1)-Smad3 pathway in UUO mice. UUO-induced NADPH oxidase activity and p22^phox expression were attenuated by DFO. In the kidneys of UUO mice, divalent metal transporter 1, ferroportin, and ferritin expression was higher and transferrin receptor expression was lower than in sham-operated mice. Increased renal iron content was observed in UUO mice, which was reduced by DFO treatment. These results suggest that iron reduction by DFO prevents renal tubulointerstitial fibrosis by regulating TGF-β-Smad signaling, oxidative stress, and inflammatory responses.

Promotion of airway anastomotic microvascular regeneration and alleviation of airway ischemia by deferoxamine nanoparticles

Airway tissue ischemia and hypoxia in human lung transplantation is a consequence of the sacrifice of the bronchial circulation during the surgical procedure and is a major risk factor for the development of airway anastomotic complications. Augmented expression of hypoxia-inducible factor (HIF)-1α promotes microvascular repair and alleviates allograft ischemia and hypoxia. Deferoxamine mesylate (DFO) is an FDA-approved iron chelator which has been shown to upregulate cellular HIF-1α. Here, we developed a nanoparticle formulation of DFO that can be topically applied to airway transplants at the time of surgery. In a mouse orthotopic tracheal transplant (OTT) model, the DFO nanoparticle was highly effective in enhancing airway microvascular perfusion following transplantation through the production of the angiogenic factors, placental growth factor (PLGF) and stromal cell-derived factor (SDF)-1. The endothelial cells in DFO treated airways displayed higher levels of p-eNOS and Ki67, less apoptosis, and decreased production of perivascular reactive oxygen species (ROS) compared to vehicle-treated airways. In summary, a DFO formulation topically-applied at the time of surgery successfully augmented airway anastomotic microvascular regeneration and the repair of alloimmune-injured microvasculature. This approach may be an effective topical transplant-conditioning therapy for preventing airway complications following clinical lung transplantation.

Can proteomics yield insight into aging aorta?

The aging aorta exhibits structural and physiological changes that are reflected in the proteome of its component cells types. The advance in proteomic technologies has made it possible to analyze the quantity of proteins associated with the natural history of aortic aging. These alterations reflect the molecular and cellular mechanisms of aging and could provide an opportunity to predict vascular health. This paper focuses on whether discoveries stemming from the application of proteomic approaches of the intact aging aorta or vascular smooth muscle cells can provide useful insights. Although there have been limited studies to date, a number of interesting proteins have been identified that are closely associated with aging in the rat aorta. Such proteins, including milk fat globule-EGF factor 8, matrix metalloproteinase type-2, and vitronectin, could be used as indicators of vascular health, or even explored as therapeutic targets for aging-related vascular diseases.

Oxidative stress increases HO-1 expression in ARPE-19 cells, but melanosomes suppress the increase when light is the stressor

PURPOSE

Phagocytized melanosomes in ARPE-19 cells were previously shown to decrease susceptibility to oxidative stress induced by hydrogen peroxide treatment and increase stress due to light irradiation relative to cells containing control black latex beads. Here we asked whether differential expression of antioxidant enzymes in cells containing pigment granules could explain the outcomes.

METHODS

ARPE-19 cells were loaded by phagocytosis with porcine RPE melanosomes or black latex beads (control particles). Heme oxygenase-1 (HO-1), HO-2, glutathione peroxidase (GPx), and catalase were quantified by Western blot analysis before and after treatment with sublethal hydrogen peroxide or blue light (400-450 nm). The stress was confirmed as sublethal by cell survival analysis using real-time quantification of propidium iodide fluorescence.

RESULTS

Phagocytosis itself produced transient changes in protein levels of some antioxidant enzymes, but steady-state levels (7 days after phagocytosis) did not differ in cells containing melanosomes versus beads. Sublethal stress, induced by either hydrogen peroxide or light, had no effect on catalase or HO-2 in either particle-free or particle-loaded cells. In contrast, HO-1 protein was upregulated by treatment with both hydrogen peroxide and light. Particle content did not affect the HO-1 increase induced by hydrogen peroxide, but the increase induced by blue light irradiation was partially blocked in cells containing black beads and blocked even more in cells containing melanosomes.

CONCLUSIONS

The results do not implicate differential antioxidant enzyme levels in stress protection by melanosomes against hydrogen peroxide, but they suggest a multifaceted role for melanosomes in regulating light stress susceptibility in RPE cells.

Angiotensin II promotes iron accumulation and depresses PGI₂ and NO synthesis in endothelial cells: effects of losartan and propranolol analogs

Angiotensin may promote endothelial dysfunction through iron accumulation. To research this, bovine endothelial cells (ECs) were incubated with iron (30 µmol·L⁻¹) with or without angiotensin II (100 nmol·L⁻¹). After incubation for 6 h, it was observed that the addition of angiotensin enhanced EC iron accumulation by 5.1-fold compared with a 1.8-fold increase for cells incubated with iron only. This enhanced iron uptake was attenuated by losartan (100 nmol·L⁻¹), d-propranolol (10 µmol·L⁻¹), 4-HO-propranolol (5 µmol·L⁻¹), and methylamine, but not by vitamin E or atenolol. After 6 h of incubation, angiotensin plus iron provoked intracellular oxidant formation (2'7'-dichlorofluorescein diacetate (DCF-DA) fluorescence) and elevated oxidized glutathione; significant loss of cell viability occurred at 48 h. Stimulated prostacyclin release decreased by 38% (6 h) and NO synthesis was reduced by 41% (24 h). Both oxidative events and functional impairment were substantially attenuated by losartan or d-propranolol. It is concluded that angiotensin promoted non-transferrin-bound iron uptake via AT-1 receptor activation, leading to EC oxidative functional impairment. The protective effects of d-propranolol and 4-HO-propranolol may be related to their lysosomotropic properties.

Synthetic and natural iron chelators: therapeutic potential and clinical use

Iron-chelation therapy has its origins in the treatment of iron-overload syndromes. For many years, the standard for this purpose has been deferoxamine. Recently, considerable progress has been made in identifying synthetic chelators with improved pharmacologic properties relative to deferoxamine. Most notable are deferasirox (Exjade(®)) and deferiprone (Ferriprox(®)), which are now available clinically. In addition to treatment of iron overload, there is an emerging role for iron chelators in the treatment of diseases characterized by oxidative stress, including cardiovascular disease, atherosclerosis, neurodegenerative diseases and cancer. While iron is not regarded as the underlying cause of these diseases, it does play an important role in disease progression, either through promotion of cellular growth and proliferation or through participation in redox reactions that catalyze the formation of reactive oxygen species and increase oxidative stress. Thus, iron chelators may be of therapeutic benefit in many of these conditions. Phytochemicals, many of which bind iron, may also owe some of their beneficial properties to iron chelation. This review will focus on the advances in iron-chelation therapy for the treatment of iron-overload disease and cancer, as well as neurodegenerative and chronic inflammatory diseases. Established and novel iron chelators will be discussed, as well as the emerging role of dietary plant polyphenols that effectively modulate iron biochemistry.

IκBβ attenuates angiotensin II-induced cardiovascular inflammation and fibrosis in mice

The development of cardiovascular fibrosis is associated with chronic inflammation, where activation of nuclear factor κB (NF-κB) signaling may play a critical role. NF-κB activation is tightly regulated by the cellular inhibitor of κB (IκB) family of proteins, such as IκBα and IκBβ. IκBα and IκBβ display different regulation kinetics in response to inflammatory stimulation. The present study tested the hypothesis that IκBα and IκBβ may have different roles in modulating cardiovascular inflammation and fibrosis, using a model of angiotensin II infusion-induced hypertension in wild-type mice and IκBβ knock-in mice, in which the IκBα gene is replaced by IκBβ cDNA (AKBI). In WT mice, subcutaneous angiotensin II infusion for 7 days induced increased perivascular and interstitial collagen deposition and fibrotic lesions, associated with myocardial interstitial hemosiderin accumulation and extensive macrophage infiltration. These effects of angiotensin II were dramatically limited in AKBI mice. Replacement of IκBα with IκBβ significantly attenuated angiotensin II infusion-induced expression of interleukin 1β, interleukin 6, monocyte chemotactic protein 1, collagen I and III, fibronectin, and tissue inhibitor of metalloproteinase 1 in the hearts. Furthermore, using cultured vascular smooth muscle cells, we demonstrated that interleukin 1β-induced NF-κB activation and monocyte chemotactic protein 1, vascular cell adhesion molecule 1, and tissue inhibitor of metalloproteinase 1 expressions were suppressed in the AKBI cells because of the replacement of IκBα with IκBβ. These results indicate that NF-κB has an essential role in mediating the cardiovascular inflammatory response to angiotensin II and suggest that targeting the balance of IκBα and IκBβ expression might be a novel therapeutic modality in preventing fibrosis in hypertensive cardiovascular disease.

Deferasirox protects against iron-induced hepatic injury in Mongolian gerbil

Iron overload is associated with an increased risk of liver complications including fibrosis, cirrhosis, and hepatocellular carcinoma. Deferasirox is a new oral chelator with high iron-binding potency and selectivity. Here we investigate the ability of deferasirox to remove excessive hepatic iron and prevent iron-induced hepatic injury. Adult male Mongolian gerbils were divided into 3 groups (n=5/group)-control, iron overload (100 mg iron-dextran/kg body weight/5 days; intraperitoneal for 10 weeks), and iron overload followed by deferasirox treatment (100 mg deferasirox/kg body weight/d; pulse oral for 1 or 3 months). Compared with the nontreated iron overload group, deferasirox reduced hepatic iron concentration by 44% after 3 months of treatment (P<0.05). Histological analysis of hepatic tissue from the iron overloaded group detected frequent iron deposition, evidence of hepatic damage, and an accumulation of lipid vacuoles. Iron deposition was significantly diminished with deferasirox treatment, and no evidence of lipid accumulation was observed. Immunoblotting demonstrated that iron overload caused approximately 2-fold increase in hepatic ferritin expression (P<0.05), which was 48% lower after 3 months of deferasirox treatment (P<0.05). Deferasirox treatment also was associated with reduced hepatic protein oxidation, superoxide abundance, and cell death. The percentage of terminal deoxynucleotidyl transferase dUTP nick end labeling positive cells in the deferasirox-treated livers was 41% lower than that of iron overloaded group (P<0.05). Similarly, an iron-related increase in the expression of Bax/Bcl2, Bad, and caspase-3 were significantly lower after deferasirox treatment. These findings suggest that deferasirox may confer protection against iron-induced hepatic toxicity.

Deferoxamine promotes angiogenesis via the activation of vascular endothelial cell function

BACKGROUND

Deferoxamine (DFO), an iron chelator for disorders of excess iron, upregulates the expression of angiogenic factors, such as vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2), indicating that it affects angiogenesis. Herein, we clarify the effect and mechanism of action of DFO on angiogenesis.

METHODS AND RESULTS

In an in vitro study, DFO increased endothelial nitric oxide synthesis (eNOS) phosphorylation in human aortic endothelial cells (HAECs), which were inhibited by the phosphatidylinositol 3-kinase inhibitor LY294002. Tube formation, cell proliferation, and cell migration in HAECs were promoted by DFO, which were significantly reduced by LY294002. In an in vivo study, DFO promoted blood flow recovery in response to the hindlimb ischemia in mice with unilateral hindlimb surgery. The density of capillaries and arterioles in ischemic muscle was higher in DFO-treated mice compared to vehicle-treated mice. Endothelial cell proliferation increased and oxidative stress and apoptosis decreased in ischemic muscles of DFO-treated mice. The phosphorylation of Akt and eNOS on the ischemic side was elevated and urinary nitric oxide/nitric dioxide (NOx) excretion was higher in DFO-treated mice compared to vehicle-treated mice. The effect of DFO on angiogenesis was abolished in eNOS-deficient mice with hindlimb ischemia.

CONCLUSION

These findings indicate that DFO promotes revascularization via the activation of vascular endothelial cell function by an Akt-eNOS-dependent mechanism.

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

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

The role of hepatocyte nuclear factor-1beta in the pathogenesis of clear cell carcinoma of the ovary

PROBLEM

Clear cell carcinoma (CCC) of the ovary has a number of features distinguishing it from other epithelial ovarian carcinomas (EOC) because of its characteristic histology and biology, frequent concurrence with endometriotic lesion, and highly chemoresistant nature resulting in an extremely poor prognosis. The incidence of CCC has been steadily increasing in Japan. They comprise approximately 20% of all EOC. Understanding the mechanisms of CCC development and elucidating pathogenesis and pathophysiology are intrinsic to prevention and effective therapies for CCC.

METHOD OF STUDY

This article reviews the English language literature for biology, pathogenesis, and pathophysiological studies on endometriosis-associated EOC. Several data are discussed in the context of endometriosis and CCC biology.

RESULTS

Recent studies based on genome-wide expression analysis technology have noted specific expression of hepatocyte nuclear factor-1beta (HNF-1beta) in endometriosis and CCC, suggesting that early differentiation into the clear cell lineage takes place in the endometriosis. The HNF-1beta-dependent pathway of CCC will be discussed, which are providing new insights into regulation of apoptosis and glycogen synthesis and resistance of CCC to anticancer agents.

CONCLUSIONS

This review summarizes recent advances in the HNF-1beta and its target genes; the potential challenges to the understanding of carcinogenesis, pathogenesis, and pathophysiology of CCC; and a possible novel model is proposed.

Inhibition of soluble epoxide hydrolase attenuated atherosclerosis, abdominal aortic aneurysm formation, and dyslipidemia

OBJECTIVE

Epoxyeicosatrienoic acids (EETs) have been shown to have antiinflammatory effects and therefore may play a role in preventing vascular inflammatory and atherosclerotic diseases. Soluble epoxide hydrolase (s-EH) converts EETs into less bioactive dihydroxyeicosatrienoic acids. Thus, inhibition of s-EH can prevent degradation of EETs and prolong their effects. The present study aimed to test the hypothesis that inhibition of s-EH has vascular protective effects.

METHODS AND RESULTS

Six-month-old apolipoprotein E-deficient mice were chronically infused with angiotensin II (1.44 mg/kg/d) for 4 weeks to induce abdominal aortic aneurysm (AAA), accelerate atherosclerosis development and carotid artery ligation-induced vascular remodeling. The mice were treated with a novel s-EH inhibitor, AR9276 (1.5 g/L in drinking water) or vehicle for 4 weeks. The results demonstrated that AR9276 significantly reduced the rate of AAA formation and atherosclerotic lesion area, but had no effect on ligation-induced carotid artery remodeling. These effects were associated with a reduction of serum lipid, IL-6, murine IL-8-KC, and IL-1alpha, and downregulation of gene expressions of ICAM-1, VCAM-1, and IL-6 in the arterial wall.

CONCLUSIONS

The present data demonstrate that treatment with an s-EH inhibitor attenuates AAA formation and atherosclerosis development. The attendant downregulation of inflammatory mediators and lipid lowering effects may both contribute to the observed vascular protective effects.

Iron behaving badly: inappropriate iron chelation as a major contributor to the aetiology of vascular and other progressive inflammatory and degenerative diseases

BACKGROUND

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular 'reactive oxygen species' (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation.

REVIEW

We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation).The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible.This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, since in some circumstances (especially the presence of poorly liganded iron) molecules that are nominally antioxidants can actually act as pro-oxidants. The reduction of redox stress thus requires suitable levels of both antioxidants and effective iron chelators. Some polyphenolic antioxidants may serve both roles.Understanding the exact speciation and liganding of iron in all its states is thus crucial to separating its various pro- and anti-inflammatory activities. Redox stress, innate immunity and pro- (and some anti-)inflammatory cytokines are linked in particular via signalling pathways involving NF-kappaB and p38, with the oxidative roles of iron here seemingly involved upstream of the IkappaB kinase (IKK) reaction. In a number of cases it is possible to identify mechanisms by which ROSs and poorly liganded iron act synergistically and autocatalytically, leading to 'runaway' reactions that are hard to control unless one tackles multiple sites of action simultaneously. Some molecules such as statins and erythropoietin, not traditionally associated with anti-inflammatory activity, do indeed have 'pleiotropic' anti-inflammatory effects that may be of benefit here.

CONCLUSION

Overall we argue, by synthesising a widely dispersed literature, that the role of poorly liganded iron has been rather underappreciated in the past, and that in combination with peroxide and superoxide its activity underpins the behaviour of a great many physiological processes that degrade over time. Understanding these requires an integrative, systems-level approach that may lead to novel therapeutic targets.

[Adrenal protein expressions after Pinggan Qianyang Formula treatment in hypertensive rats with liver-yang hyperactivity: a comparative proteomic analysis]

OBJECTIVE

To explore the pathogenic mechanism of liver-yang hyperactivity type of hypertension and to observe the effects of Pinggan Qianyang Formula (PGQYF), a compound of traditional Chinese herbals for calming the liver and suppressing yang, so as to provide experimental evidence for new marker proteins of drug therapy.

METHODS

A rat model of liver-yang hyperactivity was prepared with spontaneous hypertensive rats (SHRs) by administration of Aconiti Praeparatae Decoction. Adrenal proteins were separated by 2D gel electrophoresis (2-DE). The differentially expressed proteins were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and database analysis.

RESULTS

The rat model of liver-yang hyperactivity was successfully reproduced, and the PGQYF could decrease the grades of irritability, conjunctival congestion and systolic blood pressure of the rats (P<0.05, P<0.01). After analysis, twelve obviously differentially expressed proteins were found, eight of which were identified. The expression levels of isocitrate dehydrogenase and steroidogenic acute regulatory protein in the untreated group were up-regulated as compared with those in the normal control group, and down-regulated in the treatment group. The expression levels of ferritin light chain, elongation factor Tu, Rho GDP disassociation inhibitor 1, flavin reductase and basic transcription factor 3 in the untreated group were down-regulated as compared with those in the normal control group, and up-regulated in the treatment group.

CONCLUSION

Differentially expressed adrenal proteins in SHRs with live-yang hyperactivity are successfully identified. This approach may lay a foundation for the further investigation of pathogenic mechanisms in hypertension with liver-yang hyperactivity and the mechanisms of PGQYF treatment.

Angiotensin II-induced regulation of the expression and localization of iron metabolism-related genes in the rat kidney

Due to recent discoveries of novel genes involved in iron metabolism, our understanding of the molecular mechanisms underlying iron metabolism has dramatically increased. We have previously shown that the administration of angiotensin II alters iron homeostasis in the rat kidney, which may in turn aggravate angiotensin II-induced renal damage. Here we have investigated the effect of angiotensin II administration on the localization and expression of transferrin receptor (TfR), divalent metal transporter 1 (DMT1), ferroportin 1 (FPN), and hepcidin mRNA in the rat kidney. Weak expression of TfR, DMT1, FPN, and hepcidin mRNA was observed in the kidneys of control rats. In contrast, after 7 days of angiotensin II infusion by osmotic minipump, the expression of these mRNAs was more widely distributed. Staining of serial sections revealed that some, but not all, of the renal tubular cells positive for these genes contained iron deposits in the kidney of angiotensin II-infused animals. Real-time polymerase chain reaction (PCR) showed that the mRNA expression of TfR, iron-responsive element-negative DMT1, FPN, and hepcidin mRNA increased ~1.9-fold, ~1.7-fold, ~2.3-fold, and ~4.7-fold, respectively, after angiotensin II infusion as compared with that of untreated controls, and that these increases could be suppressed by the concomitant administration of losartan. Our data demonstrate that these genes were unequivocally expressed in the kidney and could be regulated by angiotensin II infusion. The relative contribution, if any, of these genes to renal and/or whole-body iron homeostasis in various disorders in which the renin angiotensin system is activated should be investigated in future studies.

Importance of hereditary haemochromatosis in the care of diabetes mellitus

Szerzők a vas- és a szénhidrátanyagcsere kapcsolatait vizsgálták saját és irodalmi eredmények tükrében. Különös hangsúlyt fektettek a szabad gyökös folyamatok ismertetésére, mivel a hereditaer haemochromatosis és a diabetes mellitus is, mint a vas- és a szénhidrátanyagcsere-zavarok leggyakoribbjai oxidatív stressz keltése révén vezetnek szövődményekhez. A nagy vér és szöveti glükózkoncentráció elektronfelesleget eredményez. Ez redukálhatja a redox ciklusban részt vevő, transzport- vagy raktárfehérjéhez nem kötött vasat, és ez vezet az oxidatív stresszhez. A hereditaer haemochromatosis mind a válogatás nélküli, mind pedig a diabeteses populációban a szöveti redox-aktív vas szintjének emelkedését okozhatja. A hereditaer haemochromatosis leggyakoribb mutációit hordozók aránya hazánkban, szelekció nélküli népességben 30,4%-ot és diabetesben 35,8%-ot tesz ki. Az irodalom adatai szerint feltételezhető, hogy már a hereditaer haemochromatosis leggyakoribb mutációi (HFE-C282Y és HFE-H63D) szempontjából heterozigotákban is megemelkedik a szöveti vasszint, bár a fenotípusban a hereditaer haemochromatosis ilyenkor általában nem jelenik meg, mivel penetranciája alacsony. Mégis, ez a megemelkedett vas-ellátottság a már más okból – például diabetes mellitus miatt – károsodott szövetek betegségének progresszóját okozhatja. Másrészt a hereditaer haemochromatosis olyan endothelkárosodáshoz vezethet, ami miatt – a diabetes mellitus manifesztálódását megelőzően – hypertonia alakulhat ki. Feltételezhető, hogy a vérnyomásemelkedés a hereditaer haemochromatosis egyik legkorábbi klinikai jele. Nehezen beállítható hypertonia és szénhidrátanyagcsere-zavar esetén érdemes gondolni a hereditaer haemochromatosis lehetőségére.

Magnetic resonance imaging of vulnerable atherosclerotic plaques: Current imaging strategies and molecular imaging probes

The vulnerability or destabilization of atherosclerotic plaques has been directly linked to plaque composition. Imaging modalities, such as magnetic resonance (MR) imaging, that allow for evaluation of plaque composition at a cellular and molecular level, could further improve the detection of vulnerable plaque and may allow for monitoring the efficacy of antiatherosclerotic therapies. In this review we focus on MR imaging strategies for the detection and evaluation of atherosclerotic plaques and their composition. We highlight recent advancements in the development of MR pulse sequences, computer image analysis, and the use of commercially available MR contrast agents, such as gadopentic acid (Gd-DTPA), for plaque characterization. We also discuss molecular imaging strategies that are currently being used to design specific imaging probes targeted to biochemical and cellular markers of atherosclerotic plaque vulnerability.

Expression and localization of PDGF-B, PDGF-D, and PDGF receptor in the kidney of angiotensin II-infused rat

Lipid accumulation in the kidney is a marker of tissue damage and may play a role in the development of renal injury. We have previously shown that long-term administration of angiotensin II in rats causes increased expression of transforming growth factor-beta1, coupled with an accumulation of lipids in the tubular and vascular wall cells in the kidney. In this study, we examine the regulation of expression of platelet-derived growth factor (PDGF) and its receptor system and their co-localization with lipid deposits in the kidneys of angiotensin II-infused rats. Real-time RT-PCR showed that expression of PDGF-B, PDGF-D, and PDGF receptor-beta (PDGFR-beta) mRNA was increased by angiotensin II infusion, and in situ hybridization showed the co-localization of these mRNAs. Tubular cells that had increased PDGF-B mRNA expression were positive for lipid deposition and also for cellular proliferation, which was indicated by the presence of proliferating cell nuclear antigen. By contrast, in the kidneys of angiotensin II-infused rats, apoptosis occurred in tubular cells that contained deposits of iron but not lipids. The deposition of lipids and upregulation of PDGF-B, PDGF-D, and PDGFR-beta induced by administration of angiotensin II were all suppressed by the selective angiotensin II type 1 (AT(1)) receptor antagonist losartan, but not by the nonspecific vasodilator hydralazine. The findings that lipid accumulation, upregulation of PDGF-B, PDGF-D, and PDGFR-beta, and cellular proliferation were topologically associated and regulated in an AT(1) receptor-dependent manner in the kidney of angiotensin II-infused rats suggests that these phenomena are related.

Feasibility of in vivo identification of endogenous ferritin with positive contrast MRI in rabbit carotid crush injury using GRASP

In vivo markers that allow for detection of ferritin within atheromatous plaque may be useful for identifying iron-catalyzed hydroxyl-radical formation and subsequent lipid peroxidation. Recently, a positive contrast MR technique--GRadient echo Acquisition for Superparamagnetic particles/suscePtibility (GRASP)--was used to identify the presence of magnetic entities in phantom models. The aim of the current study was to determine the feasibility of using GRASP in conjunction with conventional T(2) (*)-weighted (T(2) (*)W) gradient-echo (GRE) sequences for identifying ferritin/hemosiderin deposition using in vitro and in vivo models of thrombus. In vitro thrombi were prepared by incubating blood with ferritin. MRI was performed using conventional GRE sequences and GRASP. The results indicate that GRASP was able to verify ferritin deposition in in vitro thrombi. In vivo thrombi were created using a crush injury model in rabbits. The signal enhancement obtained using conventional GRE sequences and GRASP was compared with the location of iron deposition by histology. In all of the animals the GRASP signal correlated with signal loss by conventional GRE, and ferritin/hemosiderin deposition by histology. GRASP sequences in combination with conventional GRE sequences may be used to detect the presence of ferritin deposition in in vitro thrombi and in vivo crush-injured rabbit carotid arteries.