Abstract 15100: A Decrease in Mitochondrial, but Not Cytosolic, Iron Protects Against Cardiac Ischemia-Reperfusion Damage Through a Reduction in ROS

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Hsiang-Chun Chang ◽  
Rongxue Wu ◽  
Meng Shang ◽  
Hossein Ardehali

Introduction: Iron can catalyze the formation of reactive oxygen species (ROS) and promote tissue damage. While some studies suggested benefits with iron chelation therapy in ischemic heart disease (IHD), several others failed to show any benefits. Mitochondria are a major site of iron utilization and ROS production, and mitochondrial iron accumulation has been associated with increased oxidative stress. We therefore hypothesized that mitochondrial iron plays a causative role in ischemia/reperfusion (I/R) damage, and a decrease in mitochondrial iron (as opposed to cytoplasmic iron) would be sufficient to protect against I/R injury. Results: We observed an increase in cardiac mitochondrial iron in mice after I/R injury. Using two iron chelators with distinct mitochondrial permeability, i.e., 2,2’-bipyridyl (BPD, a mitochondria-accessible iron chelator) and deferoxamine (DFO, an iron chelator that does not modulate mitochondrial iron), we demonstrated that mice pretreated with BPD but not DFO were protected against I/R injury. Similar results were obtained in vitro . Since these two iron chelators also modulate iron in other subcellular compartments, we used transgenic (TG) mice with cardiomyocyte-specific overexpression of the mitochondrial iron export protein ATP-binding cassette (ABC)-B8 to confirm that modulation of mitochondrial iron alone is sufficient to confer protection. ABCB8 TG mice had significantly lower mitochondrial iron (but normal cytosolic iron) in the heart compared to nontransgenic (NTG) littermates at baseline, but exhibited normal cardiac function. After I/R, ABCB8 TG mice displayed significantly less apoptosis and lower levels of markers of ROS and better preserved cardiac function than NTG littermates, suggesting that a reduction in mitochondrial iron protects against I/R injury, most likely through a reduction in ROS. Conclusions: Our findings demonstrate that selective reduction in mitochondrial iron is sufficient to protect against I/R injury. Thus, targeting mitochondrial iron with selective iron chelators may provide a novel approach for the treatment of IHD.

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Hsiang-Chun Chang ◽  
Rongxue Wu ◽  
Hossein Ardehali

Introduction: Iron is essential for the activity of several cellular proteins, but excess free iron can cause cellular damage through production of reactive oxygen species (ROS). Iron accumulation in mitochondria, the major site of cellular iron homeostasis, leads to cardiomyopathy. However, it is not known whether a reduction in baseline mitochondrial (as opposed to cytosolic) iron can protect against ischemia-reperfusion (I/R) injury in the heart. We hypothesized that since mitochondria are the major site of iron homeostasis and that mitochondrial iron can lead to oxidative damage, a reduction in mitochondrial iron at baseline would be sufficient to protect against I/R injury. Results: Transgenic (TG) mice with cardiomyocyte-specific overexpression of the mitochondrial iron export protein ATP-binding cassette (ABC)-B8 had significantly lower mitochondrial iron in the heart than nontransgenic (NTG) littermates at baseline, but their cardiac function and the expression of key antioxidant systems were similar to NTG littermates. In response to I/R, TG mice displayed significantly less apoptosis and lipid peroxidation products and better preserved cardiac function than NTG littermates, suggesting that a reduction in mitochondrial iron protects against I/R injury. To confirm these results, we next took a pharmacological approach to assess the effects of a reduction in mitochondrial vs cytosolic iron on the response to I/R using 2,2’-bipyridyl (BPD, a mitochondria-accessible iron chelator) and deferoxamine (DFO, an iron chelator that can only reduce cytosolic iron). Treating rat cardiomyoblast H9C2 cells with BPD but not DFO significantly lowered chelatable mitochondrial iron and protected against H 2 O 2 induced cell death, and pretreatment with BPD but not DFO protected mice against I/R injury and reduced ROS production, suggesting that a reduction in baseline mitochondrial, but not cytosolic, iron is sufficient to protect against I/R injury. Conclusions: Our findings demonstrate that selective reduction in mitochondrial iron is protective in I/R injury. Thus, targeting mitochondrial iron with selective iron chelators may provide a novel approach for treatment of ischemic heart disease.


2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Hsiang-Chun Chang ◽  
Rongxue Wu ◽  
Hossein Ardehali

Introduction: Iron is essential for the activity of several cellular proteins, but excess free iron can cause cellular damage through production of reactive oxygen species (ROS). Iron accumulation in mitochondria, the major site of cellular iron homeostasis, leads to cardiomyopathy. However, it is not known whether a reduction in baseline mitochondrial iron (as opposed to iron in other cellular compartments) can protect against ischemia-reperfusion (I/R) injury in the heart. We hypothesized that since mitochondria are the major site of iron homeostasis and that mitochondrial iron can lead to oxidative damage, a reduction in mitochondrial iron at baseline would be sufficient to protect against I/R injury. Results: Transgenic (TG) mice with cardiomyocyte-specific overexpression of the mitochondrial iron export protein ATP-binding cassette (ABC)-B8 had significantly lower mitochondrial iron in the heart than nontransgenic (NTG) littermates at baseline, but their cardiac function and the expression of key antioxidant systems were similar to NTG littermates. In response to I/R, TG mice displayed significantly less apoptosis and lipid peroxidation products and better preserved cardiac function than NTG littermates, suggesting that a reduction in mitochondrial iron protects against I/R injury. To confirm these results, we next took a pharmacological approach to assess the effects of a reduction in mitochondrial vs cytosolic iron on the response to I/R using 2,2’-bipyridyl (BPD, a mitochondria-accessible iron chelator) and deferoxamine (DFO, an iron chelator that can only reduce cytosolic iron). Mice pretreated with BPD but not DFO are protected against I/R injury. In addition, BPD but not DFO treatment in rat cardiomyoblast H9C2 cells significantly lowered chelatable mitochondrial iron and protected against H2O2 induced cell death. These results suggest that a reduction in baseline mitochondrial, but not cytosolic, iron is sufficient to protect against I/R injury. Conclusions: Our findings demonstrate that selective reduction in mitochondrial iron is protective in I/R injury. Thus, targeting mitochondrial iron with selective iron chelators may provide a novel approach for treatment of ischemic heart disease.


2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Hsiang-Chun J Chang ◽  
Rongxue Wu ◽  
Hossein Ardehali

Introduction: Iron is essential for the activity of a large number of cellular proteins, but excess free iron can cause cellular damage through production of reactive oxygen species (ROS). Mitochondria are the major site of cellular iron homeostasis, and we recently showed the mitochondrial iron export is mediated by ATP-binding cassette protein-B8 (ABCB8). The role of mitochondrial iron in ischemia-reperfusion (I/R) injury in the heart has not been examined. We hypothesize that mitochondrial iron has a critical role in I/R damage and a reduction of mitochondrial iron is protective against I/R injury through a reduction in ROS. Results: Cardiomyocyte-specific ABCB8 transgenic (TG) mice had significantly lower mitochondrial iron in the heart than nontransgenic (NTG) littermates at baseline, but their cardiac function and the expression of key antioxidant systems were indistinguishable from NTG littermates. To study the role of mitochondrial iron in I/R injury, we subjected ABCB8 TG mice to I/R. TG mice displayed significantly less apoptosis compared to NTG littermates (11.76% vs. 17.63%, p<0.05, n=4-6) and had significantly reduced lipid peroxidation products 48 hours after I/R. To further confirm that our in vivo finding was due to reduced mitochondrial iron, we studied the effect of pharmacological reduction of mitochondrial iron in vitro. 2,2-bipyridyl (BPD) is a mitochondria-accessible iron chelator while deferoxamine (DFO) has poor penetrance into mitochondria. Treating rat cardiomyoblasts H9C2 with BPD but not DFO significantly reduced chelatable mitochondrial iron, as measured by staining cells with rhodamine B-[(1,10-phenanthrolin-5-yl)aminocarbonyl]benzyl ester. In addition, BPD but not DFO pretreatment protected cells against H2O2 induced cell death (p<0.05). BPD treatment in mice decreased baseline mitochondrial iron and significantly preserved cardiac function after I/R. Conclusions: Our findings demonstrate that selective reduction in mitochondrial iron is protective in I/R injury, and show that mitochondrial iron is a source of ROS and cellular damage in I/R. Thus, targeting mitochondrial iron with selective iron chelators, as studied in our system, may provide a novel approach for treatment of ischemic heart disease.


2021 ◽  
Vol 22 (6) ◽  
pp. 2876
Author(s):  
Víctor Vinuesa ◽  
Michael J. McConnell

Iron is essential for multiple bacterial processes and is thus required for host colonization and infection. The antimicrobial activity of multiple iron chelators and gallium-based therapies against different bacterial species has been characterized in preclinical studies. In this review, we provide a synthesis of studies characterizing the antimicrobial activity of the major classes of iron chelators (hydroxamates, aminocarboxylates and hydroxypyridinones) and gallium compounds. Special emphasis is placed on recent in-vitro and in-vivo studies with the novel iron chelator DIBI. Limitations associated with iron chelation and gallium-based therapies are presented, with emphasis on limitations of preclinical models, lack of understanding regarding mechanisms of action, and potential host toxicity. Collectively, these studies demonstrate potential for iron chelators and gallium to be used as antimicrobial agents, particularly in combination with existing antibiotics. Additional studies are needed in order to characterize the activity of these compounds under physiologic conditions and address potential limitations associated with their clinical use as antimicrobial agents.


Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Riham Abouleisa ◽  
Qinghui Ou ◽  
Xian-liang Tang ◽  
Mitesh Solanki ◽  
Yiru Guo ◽  
...  

Rationale: The regenerative capacity of the heart to repair itself after myocardial infarction (MI)is limited. Our previous study showed that ectopic introduction of Cdk1/CyclinB1 andCdk4/CyclinD1 complexes (4F) promotes cardiomyocyte proliferation in vitro and in vivo andimproves cardiac function after MI. However, its clinical application is limited due to the concernsfor tumorigenic potential in other organs. Objectives: To first, identify on a single cell transcriptomic basis the necessary reprogrammingsteps that cardiomyocytes need to undertake to progress through the proliferation processfollowing 4F overexpression, and then, to determine the pre-clinical efficacy of transient andcardiomyocyte specific expression of 4F in improving cardiac function after MI in small and largeanimals. Methods and Results: Temporal bulk and single cell RNAseq of mature hiPS-CMs treated with4F or LacZ control for 24, 48, or 72 h revealed full cell cycle reprogramming in 15% of thecardiomyocyte population which was associated with sarcomere disassembly and metabolicreprogramming. Transient overexpression of 4F specifically in cardiomyocytes was achievedusing non-integrating lentivirus (NIL) driven by TNNT2 (TNNT2-4F-NIL). One week after inductionof ischemia-reperfusion injury in rats or pigs, TNNT2-4F-NIL or control virus was injectedintramyocardially. Compared with controls, rats or pigs treated with TNNT2-4F-NIL showed a 20-30% significant improvement in ejection fraction and scar size four weeks after treatment, asassessed by echocardiography and histological analysis. Quantification of cardiomyocyteproliferation in pigs using a novel cytokinesis reporter showed that ~10% of the cardiomyocyteswithin the injection site were labelled as daughter cells following injection with TNNT2-4F-NILcompared with ~0.5% background labelling in control groups. Conclusions: We provide the first understanding of the process of forced cardiomyocyteproliferation and advanced the clinical applicability of this approach through minimization ofoncogenic potential of the cell cycle factors using a novel transient and cardiomyocyte-specificviral construct.


2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Qin Zhang ◽  
Lizhuo Ai ◽  
Lifeng Liu ◽  
Cristian Betancourt ◽  
Maura Knapp ◽  
...  

Introduction: Impaired endothelial function leads to the progression of heart failure after Ischemia-reperfusion (IR). Kinin activation of bradykinin receptor 1 (B1R), a G protein-coupled receptor that has been found to induce capillary leakage, may serve as a critical mediator in cardiac microvascular barrier dysfunction. However, the underlying mechanisms are not clear. We found that B1R inhibition abolished IR-induced endothelial matrix metalloprotease (MMP3) expression and improved endothelial barrier formation. Thus, we hypothesized that B1R antagonist protects against cardiac IR injury through an MMP3 pathway. Methods and Results: MMP3-/- mice and their littermate controls (WT) were subjected to either cardiac IR or sham control. The baseline characteristics of these mice showed minimal phenotypes. Cardiac function was determined at 3, 7 and 24 days post-IR by echocardiography. The MMP3-/- mice displayed improved cardiac function compared to the control mice, as determined by fractional shortening (26% ± 1.1 MMP3-/- vs. 21% ± 0.9 WT, p<0.05, n=5) and ejection fraction (48% ± 1.9 MMP3-/- vs. 42% ± 2.8.1 WT, p<0.05, n=5), and treating with B1R antagonist (300 μg/Kg) significantly reduced serum MMP3 levels (p<0.01). Compared to the control mice, MMP3-/- mice had significantly less infarction/area at risk 24 hours post-IR demonstrated through TTC staining. In vitro studies revealed that cellular hypoxia-reoxygenation (HR) injury significantly increased both B1R and MMP3 expression levels in primary isolated cardiac mice microvascular endothelial cells (mCMVEC). MMP3 levels were measured via ELISA. Moreover, B1R agonist treatment (1uM) increased MMP3 levels, while the use of the antagonist attenuated the increase of MMP3 in response to HR. Finally, the use of B1R antagonist improved MMP3 induced endothelial barrier dysfunction, which was measured by the electric cell-substrate impedance sensing (ECIS) system. Taken together, the results demonstrated that B1R antagonist abolished IR induced MMP3 induction and that the deletion of MMP3 is protective of cardiac function upon IR injury. Conclusions: MMP3 is a critical regulator of cardiac microvascular barrier function, and B1R/MMP3 could potentially serve as a novel therapeutic target for heart failure in response to IR injury.


Author(s):  
Andrea Pagani ◽  
B Manuela Kirsch ◽  
Ursula Hopfner ◽  
Matthias M Aitzetmueller ◽  
Elizabeth A Brett ◽  
...  

Abstract Background Hypoxia-inducible factor 1α (HIF-1α), a transcription factor responsible for tissue homeostasis and regeneration, presents reduced functionality in advanced age. In addition to absence of oxygen, sequestration of iron also stimulates HIF-1α. Therefore, we analyzed the efficacy of the iron-chelator deferiprone (DFP) at stimulating dermal fibroblasts. Objectives The main objective of this study was to quantify the DFP concentrations capable of stimulating dermal fibroblasts in vitro and to correlate the effective DFP concentrations with the ability of DFP to penetrate the epidermis, reach the dermis, and activate HIF-1α in vivo. Methods We measured cell proliferation, metabolic activity, HIF-1α expression, and lactate dehydrogenase levels of both young and aged fibroblasts after a 24-hour in vitro preconditioning with DFP. In addition, we evaluated cell survival rates and morphology with different cellular stainings. Finally, we performed a transdermal permeation study with a 1% DFP topical formulation to quantify the concentration required to reach the dermis. Results In vitro administration of iron-chelation therapy (156-312.5 µg/mL DFP ) on aged fibroblasts resulted in activation of various antiaging processes. The concentration required to reach the dermis within 24 hours was 1.5% (0.15 mg/mL), which corresponds well with the effective doses of our laboratory analyses. Conclusions The activation of HIF-1α by DFP enhances cell metabolism, proliferation, and survival of fibroblasts while reducing lactate dehydrogenase levels. Modulation of HIF-1α is linked to activation of key regeneration enzymes and proteins, and by proxy, antiaging. Therefore, the antiaging properties of DFP and its satisfactory dermal penetration make it a promising regenerative agent.


2013 ◽  
Vol 305 (4) ◽  
pp. H446-H458 ◽  
Author(s):  
Helen E. Collins ◽  
Xiaoyuan Zhu-Mauldin ◽  
Richard B. Marchase ◽  
John C. Chatham

Store-operated Ca2+ entry (SOCE) is critical for Ca2+ signaling in nonexcitable cells; however, its role in the regulation of cardiomyocyte Ca2+ homeostasis has only recently been investigated. The increased understanding of the role of stromal interaction molecule 1 (STIM1) in regulating SOCE combined with recent studies demonstrating the presence of STIM1 in cardiomyocytes provides support that this pathway co-exists in the heart with the more widely recognized Ca2+ handling pathways associated with excitation-contraction coupling. There is now substantial evidence that STIM1-mediated SOCE plays a key role in mediating cardiomyocyte hypertrophy, both in vitro and in vivo, and there is growing support for the contribution of SOCE to Ca2+ overload associated with ischemia/reperfusion injury. Here, we provide an overview of our current understanding of the molecular regulation of SOCE and discuss the evidence supporting the role of STIM1/Orai1-mediated SOCE in regulating cardiomyocyte function.


2013 ◽  
Vol 304 (7) ◽  
pp. H966-H982 ◽  
Author(s):  
Akihiro Masuzawa ◽  
Kendra M. Black ◽  
Christina A. Pacak ◽  
Maria Ericsson ◽  
Reanne J. Barnett ◽  
...  

Mitochondrial damage and dysfunction occur during ischemia and modulate cardiac function and cell survival significantly during reperfusion. We hypothesized that transplantation of autologously derived mitochondria immediately prior to reperfusion would ameliorate these effects. New Zealand White rabbits were used for regional ischemia (RI), which was achieved by temporarily snaring the left anterior descending artery for 30 min. Following 29 min of RI, autologously derived mitochondria (RI-mitochondria; 9.7 ± 1.7 × 106/ml) or vehicle alone (RI-vehicle) were injected directly into the RI zone, and the hearts were allowed to recover for 4 wk. Mitochondrial transplantation decreased ( P < 0.05) creatine kinase MB, cardiac troponin-I, and apoptosis significantly in the RI zone. Infarct size following 4 wk of recovery was decreased significantly in RI-mitochondria (7.9 ± 2.9%) compared with RI-vehicle (34.2 ± 3.3%, P < 0.05). Serial echocardiograms showed that RI-mitochondria hearts returned to normal contraction within 10 min after reperfusion was started; however, RI-vehicle hearts showed persistent hypokinesia in the RI zone at 4 wk of recovery. Electrocardiogram and optical mapping studies showed that no arrhythmia was associated with autologously derived mitochondrial transplantation. In vivo and in vitro studies show that the transplanted mitochondria are evident in the interstitial spaces and are internalized by cardiomyocytes 2–8 h after transplantation. The transplanted mitochondria enhanced oxygen consumption, high-energy phosphate synthesis, and the induction of cytokine mediators and proteomic pathways that are important in preserving myocardial energetics, cell viability, and enhanced post-infarct cardiac function. Transplantation of autologously derived mitochondria provides a novel technique to protect the heart from ischemia-reperfusion injury.


2019 ◽  
Vol 19 (19) ◽  
pp. 1564-1576
Author(s):  
Mousumi Shyam ◽  
Abhimanyu Dev ◽  
Barij Nayan Sinha ◽  
Venkatesan Jayaprakash

:Iron overload disorder and diseases where iron mismanagement plays a crucial role require orally available iron chelators with favourable pharmacokinetic and toxicity profile. Desferrithiocin (DFT), a tridentate and orally available iron chelator has a favourable pharmacokinetic profile but its use has been clinically restricted due to its nephrotoxic potential. The chemical architecture of the DFT has been naturally well optimized for better iron chelation and iron clearance from human biological system. Equally they are also responsible for its toxicity. Hence, subsequent research has been devoted to develop a non-nephrotoxic analogue of DFT without losing its iron clearance ability.:The review has been designed to classify the compounds reported till date and to discuss the structure activity relationship with reference to modifications attempted at different positions over pyridine and thiazoline ring of DFT. Compounds are clustered under two major classes: (i) Pyridine analogues and (ii) phenyl analogue and further each class has been further subdivided based on the presence or absence and the number of hydroxy functional groups present over pyridine or phenyl ring of the DFT analogues. Finally a summary and few insights into the development of newer analogues are provided.


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