Beneficial effects of carbon monoxide-releasing molecule-2 (CORM-2) on acute doxorubicin cardiotoxicity in mice: role of oxidative stress and apoptosis

Dual delivery of carbon monoxide and doxorubicin using haemoglobin-albumin cluster: proof of concept for well-tolerated cancer therapy

A serious concern of doxorubicin (DOX) therapy is that it causes severe adverse effects, particularly cardiotoxicity. Carbon monoxide (CO) possesses powerful cytoprotective effects against drug-induced organ injury and is expected to ameliorate DOX-induced cardiotoxicity. In this study, a dual carrier of DOX and CO (CO-HemoAct-DOX) was fabricated based on a haemoglobin-albumin cluster (HemoAct), which is a protein cluster with a haemoglobin core structure wrapped by serum albumin. CO-HemoAct-DOX was synthesised by binding CO to a haemoglobin core and covalently conjugating (6-maleimidocaproyl)hydrazone derivative of DOX to an albumin shell. The average DOX/cluster ratio was about 2.6. In the in vitro cytotoxicity assay against cancer cells, the anti-tumour activity of CO-HemoAct-DOX was 10-fold lower than that of DOX in a 2D-cultured model, whereas CO-HemoAct-DOX suppressed the growth of tumour spheroids to the same extent as DOX in the 3D-cultured model. In colon-26 tumour-bearing mice, CO-HemoAct-DOX achieved DOX delivery to the tumour site and alleviated tumour growth more effectively than DOX. Furthermore, CO-HemoAct attenuated DOX-induced cardiomyocyte atrophy in H9c2 cells and elevated the levels of cardiac biomarkers in mice exposed to DOX. These results suggest that the dual delivery of CO and DOX using HemoAct is a promising strategy as an anti-tumour agent to realise well-tolerated cancer therapy with minimal cardiotoxicity.

Beneficial Effects of Oral Carbon Monoxide on Doxorubicin-Induced Cardiotoxicity

BACKGROUND

Doxorubicin and other anthracyclines are crucial cancer treatment drugs. However, they are associated with significant cardiotoxicity, severely affecting patient care and limiting dosage and usage. Previous studies have shown that low carbon monoxide (CO) concentrations protect against doxorubicin toxicity. However, traditional methods of CO delivery pose complex challenges for daily administration, such as dosing and toxicity. To address these challenges, we developed a novel oral liquid drug product containing CO (HBI-002) that can be easily self-administered by patients with cancer undergoing doxorubicin treatment, resulting in CO being delivered through the upper gastrointestinal tract.

METHODS AND RESULTS

HBI-002 was tested in a murine model of doxorubicin cardiotoxicity in the presence and absence of lung or breast cancer. The mice received HBI-002 twice daily before doxorubicin administration and experienced increased carboxyhemoglobin levels from a baseline of ≈1% to 7%. Heart tissue from mice treated with HBI-002 had a 6.3-fold increase in CO concentrations and higher expression of the cytoprotective enzyme heme oxygenase-1 compared with placebo control. In both acute and chronic doxorubicin toxicity scenarios, HBI-002 protected the heart from cardiotoxic effects, including limiting tissue damage and cardiac dysfunction and improving survival. In addition, HBI-002 did not compromise the efficacy of doxorubicin in reducing tumor volume, but rather enhanced the sensitivity of breast 4T1 cancer cells to doxorubicin while simultaneously protecting cardiac function.

CONCLUSIONS

These findings strongly support using HBI-002 as a cardioprotective agent that maintains the therapeutic benefits of doxorubicin cancer treatment while mitigating cardiac damage.

Recent progress on anti-nociceptive effects of carbon monoxide releasing molecule-2 (CORM-2)

The role of carbon monoxide (CO) has evolved albeit controversial disputes on its toxicity. This biological gasotransmitter participates in the endogenous regulation of neurotransmitters and neuropeptides released in the nervous system. Exogenous CO gas inhalation at a lower concentration has been the subject of investigations, which have revealed its biological homeostatic mechanisms and protective effects against many pathological conditions. This therapeutic procedure of CO is, however, limited due to its immediate release, which favours haemoglobin at a high affinity with the subsequent generation of toxic carboxyhaemoglobin in tissues. In order to address this problem, carbon monoxide releasing molecule-2 (CORM-2) or also known as tricarbonyldichlororuthenium II dimer is developed to liberate a controlled amount of CO in the biological systems. In this review, we examine several potential mechanisms exerted by this therapeutic compound to produce the anti-nociceptive effect that has been demonstrated in previous studies. This review could shed light on the role of CORM-2 to reduce pain, especially in cases of chronic and neuropathic pain.

CORM‑2 reduces cisplatin accumulation in the mouse inner ear and protects against cisplatin-induced ototoxicity

INTRODUCTION

Cisplatin is a life-saving anticancer compound used to treat multiple solid malignant tumors, while it causes permanent hearing loss. There is no known cure, and the FDA has not approved any preventative treatment for cisplatin-based ototoxicity.

OBJECTIVES

This study investigated whether the carbon monoxide (CO)-releasing tricarbonyldichlororuthenium (II) dimer, CORM-2, reverses cisplatin-induced hearing impairment and reduces cisplatin accumulation in the mouse inner ear.

METHODS

Male 6-week-old BALB/c mice were randomly assigned to one of the following groups: control (saline-treated, i.p.), CORM-2 only (30 mg/kg, i.p., four doses), cisplatin only (20 mg/kg, i.p., one dose), and CORM-2 + cisplatin, to determine whether cisplatin-based hearing impairment was alleviated by CORM-2 treatment.

RESULTS

Our results revealed CORM-2 significantly attenuated cisplatin-induced hearing loss in young adult mice. CORM-2 co-treatment significantly decreased platinum accumulation in the inner ear and activated the plasma membrane repair system of the stria vascularis. Moreover, CORM-2 co-treatment significantly decreased cisplatin-induced inflammation, apoptosis, and cochlear necroptosis. Because the stria vascularis is the likely cochlear entry point of cisplatin, we next focused on the microvasculature. Cisplatin induced increased extravasation of a chromatic tracer (fluorescein isothiocyanate [FITC]-dextran, MW 75 kDa) around the cochlear microvessels at 4 days post-treatment; this extravasation was completely inhibited by CORM-2 co-therapy. CORM-2 co-treatment effectively maintained the integrity of stria vascularis components including endothelial cells, pericytes, and perivascular-resident macrophage-type melanocytes.

CONCLUSION

CORM-2 co-therapy substantially protects against cisplatin-induced ototoxicity by reducing platinum accumulation and toxic cellular stress responses. These data indicate that CORM-2 co-treatment may be translated into clinical strategy to reduce cisplatin-induced hearing loss.

The Role of Epithelial Mesenchymal Transition (EMT) in Pathogenesis of Cardiotoxicity: Diagnostic & Prognostic Approach

Cancer is one of the diseases, which it is not still completely curable; the existing treatments are associated with many complications, that double its complexity. One of the causes of cancer cell metastasis is Epithelial Mesenchymal Transition (EMT). Recently study demonstrated that EMT cause cardiotoxicity and heart diseases such as heart failure, hypertrophy and fibrosis. This study evaluated molecular and signaling pathway, which lead to cardiotoxicity via EMT. It was demonstrated that the processes of inflammation, oxidative stress and angiogenesis were involved in EMT and cardiotoxicity. The pathways related to these processes act as a double-edged sword. In relation to inflammation and oxidative stress, molecular pathways caused apoptosis of cardiomyocytes and cardiotoxicity induction. While the angiogenesis process inhibits cardiotoxicity despite the progression of EMT. On the other hand, some molecular pathways such as PI3K/mTOR despite causing the progression of EMT lead to the proliferation of cardiomyocytes and prevent cardiotoxicity. Therefore, it was concluded that the identification of molecular pathways can help in designing therapeutic and preventive strategies to increase patients' survival.

Ultrasound-Mediated Antitumor Therapy via Targeted Acoustic Release Carrier of Carbon Monoxide (TARC-CO)

As one of the most valuable endogenous gas signaling molecules, carbon monoxide (CO) has been demonstrated in numerous studies to show excellent promise in the treatment of diseases, such as cancer. However, for many years, the inherent high affinity of CO for hemoglobin severely impeded the clinical transformation of CO-based treatments. Therefore, the controlled delivery of CO to target tissues has become a common challenge. Herein, an efficient ultrasonic-triggered and targeted CO release strategy was constructed based on a novel targeted acoustic release carrier of carbon monoxide (TARC-CO) that we synthesized in this study. The designed TARC-COs could afford a safe, stable, and ultrasound-guided delivery of CO in vivo by loading a specified dose of CO inside microbubbles, resulting in breast tumor suppression. Taking advantage of the high loading capacity of microbubbles, the unit volume of TARC-CO suspension could encapsulate up to 337.1 ± 8.0 (×10³ ppm) of CO. In addition, the satisfactory ultrasound contrast-enhanced ability of TARC-COs achieved real-time interactive guidance and visual policing of CO delivery. For the in vitro antitumor study, TARC-COs with ultrasonic irradiation were demonstrated to effectively induce mitochondrial dysfunction by reducing mitochondrial membrane potential, leading to the apoptosis of 4T1 cells. In addition, we realized that TARC-CO-based treatment could significantly slow the growth rate of tumors by inducing apoptosis, inhibiting the proliferation of cancer cells, and limiting tumor angiogenesis. In summary, this proof-of-concept study demonstrates the feasibility and tremendous potential of TARC-COs for controlled release of CO, which can be expected to provide new inspirations and a promising perspective for therapy based on active gases.

Evaluating the effects of carbon monoxide releasing molecule-2 against myocardial ischemia-reperfusion injury in ovariectomized female rats

PURPOSE

Cardioprotective effect of carbon monoxide, a gasotransmitter against myocardial ischemia-reperfusion injury (I/R), is well established in preclinical studies with male rats. However, its ischemic tolerance in post-menopausal animals has not been examined due to functional perturbations at the cellular level.

METHODS

The protective role of carbon monoxide releasing molecule-2 (CORM-2) on myocardial I/R was studied in female Wistar rats using the Langendorff apparatus. The animals were randomly divided into normal and ovariectomized (Ovx) female rats and were maintained 2 months post-surgery. Each group was further divided into 4 subgroups (n = 6/subgroup): normal, I/R, CORM-2-control (20 μmol/L), and CORM-2-I/R. The cardiac injury was estimated via myocardial infarct size, lactate dehydrogenase, and creatine kinase levels in coronary effluent and cardiac hemodynamic indices. Mitochondrial functional activity was assessed by measuring mitochondrial electron transport chain enzyme activities, swelling behavior, mitochondrial membrane potential, and oxidative stress.

RESULTS

Hemodynamic indices were significantly lower in ovariectomized rat hearts than in normal rat hearts. Sixty minutes of reperfusion of ischemic heart exhibited deteriorated cardiac physiological recovery in both ovariectomized and normal groups, where prominent decline was observed in ovariectomized rat. However, preconditioning the isolated heart with CORM-2 improved hemodynamics parameters significantly in both ovariectomized and normal rat hearts challenged with I/R, but with a limited degree of protection in ovariectomized rat hearts. The protective effect of CORM-2 was further confirmed via a reduction in cardiac injury, preservation of mitochondrial enzymes, and reduction in oxidative stress in all groups.

CONCLUSION

CORM-2 administration significantly attenuated myocardial I/R injury in ovariectomized rat hearts by attenuating I/R-associated mitochondrial perturbations and reducing oxidative stress.

Nature's marvels endowed in gaseous molecules I: Carbon monoxide and its physiological and therapeutic roles

Nature has endowed gaseous molecules such as O2, CO2, CO, NO, H2S, and N2 with critical and diverse roles in sustaining life, from supplying energy needed to power life and building blocks for life's physical structure to mediating and coordinating cellular functions. In this article, we give a brief introduction of the complex functions of the various gaseous molecules in life and then focus on carbon monoxide as a specific example of an endogenously produced signaling molecule to highlight the importance of this class of molecules. The past twenty years have seen much progress in understanding CO's mechanism(s) of action and pharmacological effects as well as in developing delivery methods for easy administration. One remarkable trait of CO is its pleiotropic effects that have few parallels, except perhaps its sister gaseous signaling molecules such as nitric oxide and hydrogen sulfide. This review will delve into the sophistication of CO-mediated signaling as well as its validated pharmacological functions and possible therapeutic applications.

DNA damage and antioxidant properties of CORM-2 in normal and cancer cells

In this study, we compared the effect of tricarbonyldichlororuthenium (II) dimer (CORM-2) and its CO-depleted molecule (iCORM-2) on human peripheral blood mononuclear cells (PBMCs) and human promyelocytic leukemia HL-60 cells. We determined cell viability, DNA damage and DNA repair kinetics. We also studied the effect of both compounds on DNA oxidative damage, free radical level and HO-1 gene expression. We showed that at low concentrations both CORM-2 and iCORM-2 stimulate PBMCs viability. After 24-h incubation, CORM-2 and iCORM-2, at the concentration of 100 µM, reduce the viability of both PBMCs and HL-60 cells. We also demonstrated that CORM-2 and iCORM-2, in the 0.01–100 µM concentration range, cause DNA damage such as strand breaks and alkaline labile sites. DNA damage was repaired efficiently only in HL-60 cells. CORM-2 significantly reduces oxidative stress induced by 1 mM H₂O₂ in normal and cancer cells. On the contrary, iCORM-2 in HL-60 cells increases the level of free radicals in the presence of 1 and 5 mM H₂O₂. We also revealed that both CORM-2 and iCORM-2 induce HO-1 gene expression. However, CORM-2 induces this gene to a greater extent than iCORM-2, especially in HL-60 cells at 100 µM. Finally, we showed that CORM-2 and iCORM-2 reduce H₂O₂-induced DNA oxidative damage. Furthermore, CORM-2 proved to be a compound with stronger antioxidant properties than iCORM-2. Our results suggest that both active CORM-2 and inactive iCORM-2 exert biological effects such as cyto- and genotoxicity, antioxidant properties and the ability to induce the HO-1 gene. The released CO as well as iCORM-2 can be responsible for these effects.

Nitro reduction-based fluorescent probes for carbon monoxide require reactivity involving a ruthenium carbonyl moiety

Recently, several arylnitro-based fluorescent CO probes have been reported. The design was based on CO's ability to reduce an arylnitro group for fluorescence turn-on. In this work, we assessed the response of three published arylnitro-based fluorescent CO probes, namely COFP, LysoFP-NO2, and NIR-CO toward CO from various sources. We found that only ruthenium-based CO releasing molecules (CO-RMs) were able to turn on the fluorescence while pure CO gas and CO from other sources did not turn-on the probe in the absence of ruthenium. Further experiments with different ruthenium complexes indicate that the reduction of arylnitro group requires the ruthenium carbonyl complex as an essential ingredient. As further confirmation, we also conducted the reduction of the nitro group in a p-nitrobenzamide compound and came to the same conclusion. As such, COFP and related arynitro-based probes are able to sense CORM-2 and CORM-3, but not CO in general. Our findings also indicate the need to use CO from various sources in future assessment of new CO probes.

Carbon monoxide: An emerging therapy for acute kidney injury

Treating acute kidney injury (AKI) represents an important unmet medical need both in terms of the seriousness of this medical problem and the number of patients. There is also a large untapped market opportunity in treating AKI. Over the years, there has been much effort in search of therapeutics with minimal success. However, over the same time period, new understanding of the underlying pathobiology and molecular mechanisms of kidney injury have undoubtedly helped the search for new therapeutics. Along this line, carbon monoxide (CO) has emerged as a promising therapeutic agent because of its demonstrated cytoprotective, and immunomodulatory effects. CO has also been shown to sensitize cancer, but not normal cells, to chemotherapy. This is particularly important in treating cisplatin-induced AKI, a common clinical problem that develops in patients receiving cisplatin therapies for a number of different solid organ malignancies. This review will examine and make the case that CO be developed into a therapeutic agent against AKI.

Emerging Delivery Strategies of Carbon Monoxide for Therapeutic Applications: from CO Gas to CO Releasing Nanomaterials

Carbon monoxide (CO) therapy has emerged as a hot topic under exploration in the field of gas therapy as it shows the promise of treating various diseases. Due to the gaseous property and the high affinity for human hemoglobin, the main challenges of administrating medicinal CO are the lack of target selectivity as well as the toxic profile at relatively high concentrations. Although abundant CO releasing molecules (CORMs) with the capacity to deliver CO in biological systems have been developed, several disadvantages related to CORMs, including random diffusion, poor solubility, potential toxicity, and lack of on-demand CO release in deep tissue, still confine their practical use. Recently, the advent of versatile nanomedicine has provided a promising chance for improving the properties of naked CORMs and simultaneously realizing the therapeutic applications of CO. This review presents a brief summarization of the emerging delivery strategies of CO based on nanomaterials for therapeutic application. First, an introduction covering the therapeutic roles of CO and several frequently used CORMs is provided. Then, recent advancements in the synthesis and application of versatile CO releasing nanomaterials are elaborated. Finally, the current challenges and future directions of these important delivery strategies are proposed.

Heme, Heme Oxygenase, and Endoplasmic Reticulum Stress-A New Insight into the Pathophysiology of Vascular Diseases

The prevalence of vascular disorders continues to rise worldwide. Parallel with that, new pathophysiological pathways have been discovered, providing possible remedies for prevention and therapy in vascular diseases. Growing evidence suggests that endoplasmic reticulum (ER) stress is involved in a number of vasculopathies, including atherosclerosis, vascular brain events, and diabetes. Heme, which is released from hemoglobin or other heme proteins, triggers various pathophysiological consequence, including heme stress as well as ER stress. The potentially toxic free heme is converted by heme oxygenases (HOs) into carbon monoxide (CO), iron, and biliverdin (BV), the latter of which is reduced to bilirubin (BR). Redox-active iron is oxidized and stored by ferritin, an iron sequestering protein which exhibits ferroxidase activity. In recent years, CO, BV, and BR have been shown to control cellular processes such as inflammation, apoptosis, and antioxidant defense. This review covers our current knowledge about how heme induced endoplasmic reticulum stress (HIERS) participates in the pathogenesis of vascular disorders and highlights recent discoveries in the molecular mechanisms of HO-mediated cytoprotection in heme stress and ER stress, as well as crosstalk between ER stress and HO-1. Furthermore, we focus on the translational potential of HIERS and heme oxygenase-1 (HO-1) in atherosclerosis, diabetes mellitus, and brain hemorrhage.

A medicinal and edible formula YH0618 ameliorates the toxicity induced by Doxorubicin via regulating the expression of Bax/Bcl-2 and FOXO4

Chemotherapy is the most common and powerful cancer treatment. Although the nasty side effects seriously influence the clinical practice, no better ways can displace it. Therefore, searching for safe and effective strategies designed to ameliorate chemotherapy-induced toxicity has become an urgent issue in cancer research area. In clinical, a medicinal and edible formula YH0618 showed the effects of reducing the DOX-induced toxicity, especially improving alopecia, nail discoloration, skin hyperpigmentation and fatigue. This study was to investigate the role and mechanism of YH0618 in ameliorating DOX-induced toxicity by in vitro and in vivo experiments. YH0618 selectively attenuated DOX-induced growth inhibition and apoptosis in human normal liver L02 cells and kidney HEK-293 cells, and simultaneously potentiated the anti-cancer effect of DOX in breast cancer MCF-7 and MDA-MB-231 cells by apoptosis pathways. Western blotting results revealed that YH0618 attenuated DOX-induced apoptosis in normal liver and kidney cells through FOXO4-mediated mitochondria-dependent mechanism. Animal experiments demonstrated that, YH0618 did not interfere in DOX-induced reduction in tumor volume and significantly improved DOX-induced hair loss and the increase of alanine aminotransferase (ALT). Histological characteristics showed that YH0618 attenuated DOX-induced heart, liver and kidney damage. The study may shed light on the potential application of YH0618 as a novel medicinal food against chemotherapy-induced toxicity.

Protective effects of carbon monoxide releasing molecule‑2 on pancreatic function in septic mice

The present study aimed to investigate the effect of carbon monoxide (CO)‑releasing molecule‑2 (CORM‑2) on pancreatic function in sepsis‑model mice. To perform the present investigation, mice were rendered septic by cecal ligation and puncture (CLP). Then, mice were either treated with or without CORM‑2 (8 mg/kg, intravenous) for different durations (6, 12 and 24 h) immediately following CLP. The levels of serum amylase and lipase, tumor necrosis factor α, interleukin‑1β and interleukin‑6 in addition to myeloperoxidase (MPO) activity in pancreatic tissues were determined at 6, 12 and 24 h post‑CLP. Histological scores and the expression of intercellular adhesion molecule 1 (ICAM‑1), vascular cell adhesion molecule 1 (VCAM‑1), nuclear factor‑κB (NF‑κB) and phosphorylated inhibitor of κB (p‑IκB‑α) in the pancreas were also evaluated at 24 h post‑CLP. The results of the present study revealed that compared with CLP‑alone group, CORM‑2 treatment significantly (P<0.05) reduced the levels of serum amylase, lipase and pro‑inflammatory cytokines. In parallel, the severity of pancreatic histology, MPO activity and the expression levels of ICAM‑1 and VCAM‑1 in the pancreas of CORM‑2 treated CLP mice were substantially decreased compared with the untreated group. Furthermore, CORM‑2 treatment inhibited the expression levels of NF‑κB and P‑IκB‑α in the pancreas of mice following CLP compared with the untreated group. CORM‑2‑liberated CO exerted protective effects on the pancreatic function of septic mice, and the beneficial effects may be due to the suppression of NF‑κB activation and subsequent regulation of NF‑κB‑dependent expression of cytokines.

Carbon monoxide and its donors - their implications for medicine

Inhalation of high concentrations of carbon monoxide (CO) is known to lead to serious systemic complications and neuronal disturbances. However, it has been found that not only is CO produced endogenously, but also that low concentrations can bestow beneficial effects which may be of interest in biology and medicine. As translocation of CO through the human organism is difficult, small molecules known as CO-releasing molecules (CORMs) deliver controlled amounts of CO to biological systems, and these are of great interest from a medical point of view. These actions may prevent vascular dysfunction, regulate blood pressure, inhibit blood platelet aggregation or have anti-inflammatory effects. This review summarizes the functions of various CO-releasing molecules in biology and medicine.

Heme oxygenase-1 prevents heart against myocardial infarction by attenuating ischemic injury-induced cardiomyocytes senescence

Background

Cellular senescence is a stable cell-cycle arrest induced by telomere shortening and various types of cellular stress including oxidative stress, oncogene activation, DNA damage etc. Heme oxygenase-1 (HO-1) is an inducible stress-response protein that plays antioxidant and anti-apoptotic effects. However, the role and underlying mechanisms of HO-1 in cellular senescence in heart are largely unknown.

Methods

Echocardiography was employed to detect the effect of HO-1 on heart function in adult mice with myocardial infarction (MI) and aged mice. The senescence markers, p53, p16 and LaminB, were analyzed by western blot. The immunofluorescence and immunohistochemical staining were applied to analyze the expression level of p16. SA-β-Gal staining showed the level of cardiomyocyte senescence.

Findings

We found that hemin significantly induced the expression of HO-1, which notably suppressed cardiomyocyte senescence containing the secretion of senescence-associated secretory phenotype. Further studies showed that systemic HO-1 transgenic overexpression improved heart function by inhibiting aging-induced extracellular matrix deposition and fibrogenesis. More importantly, treatment of hemin improved heart function in MI mice. Furthermore, forced expression of HO-1 blunted cardiomyocyte senescence in natural aged mice and in primary cultured neonatal mouse cardiomyocytes.

Interpretation

Our study revealed that HO-1 improved heart function and attenuated cardiomyocyte senescence triggered by ischemic injury and aging. In addition, HO-1 induction alleviated H₂O₂-induced cardiomyocyte senescence. Finally, our study suggested a novel mechanism of HO-1 to play cardioprotective effect.

Fund

This study was supported by the National Natural Science Foundation of China (81770284 to Hongli Shan); and the National Natural Science Foundation of China (81673425, 81872863 to Yuhong Zhou). The National Natural Science Foundation of China (81473213 to Chaoqian Xu). National Key R&D Program of China (2017YFC1307403 to Baofeng Yang), National Natural Science Foundation of China (81730012 to Baofeng Yang).

Gas-Generating Nanoplatforms: Material Chemistry, Multifunctionality, and Gas Therapy

The fast advances of theranostic nanomedicine enable the rational design and construction of diverse functional nanoplatforms for versatile biomedical applications, among which gas-generating nanoplatforms (GGNs) have emerged very recently as unique theranostic nanoplatforms for broad gas therapies. Here, the recent developments of the rational design and chemical construction of versatile GGNs for efficient gas therapies by either exogenous physical triggers or endogenous disease-environment responsiveness are reviewed. These gases involve some therapeutic gases that can directly change disease status, such as oxygen (O₂ ), nitric oxide (NO), carbon monoxide (CO), hydrogen (H₂ ), hydrogen sulfide (H₂ S) and sulfur dioxide (SO₂ ), and other gases such as carbon dioxide (CO₂ ), dl-menthol (DLM), and gaseous perfluorocarbon (PFC) for supplementary assistance of the theranostic process. Abundant nanocarriers have been adopted for gas delivery into lesions, including poly(d,l-lactic-co-glycolic acid), micelles, silica/mesoporous silica, organosilica, MnO₂ , graphene, Bi₂ Se₃ , upconversion nanoparticles, CaCO₃ , etc. Especially, these GGNs have been successfully developed for versatile biomedical applications, including diagnostic imaging and therapeutic use. The biosafety issue, challenges faced, and future developments on the rational construction of GGNs are also discussed for further promotion of their clinical translation to benefit patients.

An Overview of the Potential Therapeutic Applications of CO-Releasing Molecules

Carbon monoxide (CO) has long been known as the “silent killer” owing to its ability to form carboxyhemoglobin—the main cause of CO poisoning in humans. Its role as an endogenous neurotransmitter, however, was suggested in the early 1990s. Since then, the biological activity of CO has been widely examined via both the direct administration of CO and in the form of so-called “carbon monoxide releasing molecules (CORMs).” This overview will explore the general physiological effects and potential therapeutic applications of CO when delivered in the form of CORMs.

Carbon Monoxide Ameliorates 6-Hydroxydopamine-Induced Cell Death in C6 Glioma Cells

Carbon monoxide (CO) is well-known as toxic gas and intrinsic signaling molecule such as neurotransmitter and blood vessel relaxant. Recently, it has been reported that low concentration of CO exerts therapeutic actions under various pathological conditions including liver failure, heart failure, gastric cancer, and cardiac arrest. However, little has been known about the effect of CO in neurodegenerative diseases like Parkinson's disease (PD). To test whether CO could exert a beneficial action during oxidative cell death in PD, we examined the effects of CO on 6-hydroxydopamine (6-OHDA)-induced cell death in C6 glioma cells. Treatment of CO-releasing molecule-2 (CORM-2) significantly attenuated 6-OHDA-induced apoptotic cell death in a dose-dependent manner. CORM-2 treatment decreased Bax/Bcl2 ratio and caspase-3 activity, which had been increased by 6-OHDA. CORM-2 increased phosphorylation of NF-E2-related factor 2 (Nrf2) which is a transcription factor regulating antioxidant proteins. Subsequently, CORM-2 also increased the expression of heme oxygenase-1 and superoxide dismutases (CuZnSOD and MnSOD), which were antioxidant enzymes regulated by Nrf2. These results suggest that CO released by CORM-2 treatment may have protective effects against oxidative cell death in PD through the potentiation of cellular adaptive survival responses via activation of Nrf2 and upregulation of heme oxygenase-1, leading to increasing antioxidant defense capacity.

Click, Release, and Fluoresce: A Chemical Strategy for a Cascade Prodrug System for Codelivery of Carbon Monoxide, a Drug Payload, and a Fluorescent Reporter

A chemical strategy was developed wherein a single trigger sets in motion a three-reaction cascade leading to the release of more than one drug-component in sequence with the generation of a fluorescent side product for easy monitoring. As a proof of concept, codelivery of CO with the antibiotic metronidazole was demonstrated.

Carbon Monoxide in Meat and Fish Packaging: Advantages and Limits

Due to increased demands for greater expectation in relation to quality, convenience, safety and extended shelf-life, combined with growing demand from retailers for cost-effective extensions of fresh muscle foods’ shelf-life, the food packaging industry quickly developed to meet these expectations. During the last few decades, modified atmosphere packaging (MAP) of foods has been a promising area of research, but much remains to be known regarding the use of unconventional gases such carbon monoxide (CO). The use of CO for meat and seafood packaging is not allowed in most countries due to the potential toxic effect, and its use is controversial in some countries. The commercial application of CO in food packaging was not then considered feasible because of possible environmental hazards for workers. CO has previously been reported to mask muscle foods’ spoilage, and this was the primary concern raised for the prohibition, as this may mislead consumers. This review was undertaken to present the most comprehensive and current overview of the widely-available, scattered information about the use of CO in the preservation of muscle foods. The advantages of CO and its industrial limits are presented and discussed. The most recent literature on the consumer safety issues related to the use of CO and consumer acceptance of CO especially in meat packaging systems were also discussed. Recommendations and future prospects were addressed for food industries, consumers and regulators on what would be a “best practice” in the use of CO in food packaging. All this promotes high ethical standards in commercial communications by means of effective regulation, for the benefit of consumers and businesses in the world, and this implies that industrialized countries and members of their regulatory agencies must develop a coherent and robust systems of regulation and control that can respond effectively to new challenges.

Intermittent, low dose carbon monoxide exposure enhances survival and dopaminergic differentiation of human neural stem cells

Exploratory studies using human fetal tissue have suggested that intrastriatal transplantation of dopaminergic neurons may become a future treatment for patients with Parkinson's disease. However, the use of human fetal tissue is compromised by ethical, regulatory and practical concerns. Human stem cells constitute an alternative source of cells for transplantation in Parkinson's disease, but efficient protocols for controlled dopaminergic differentiation need to be developed. Short-term, low-level carbon monoxide (CO) exposure has been shown to affect signaling in several tissues, resulting in both protection and generation of reactive oxygen species. The present study investigated the effect of CO produced by a novel CO-releasing molecule on dopaminergic differentiation of human neural stem cells. Short-term exposure to 25 ppm CO at days 0 and 4 significantly increased the relative content of β-tubulin III-immunoreactive immature neurons and tyrosine hydroxylase expressing catecholaminergic neurons, as assessed 6 days after differentiation. Also the number of microtubule associated protein 2-positive mature neurons had increased significantly. Moreover, the content of apoptotic cells (Caspase3) was reduced, whereas the expression of a cell proliferation marker (Ki67) was left unchanged. Increased expression of hypoxia inducible factor-1α and production of reactive oxygen species (ROS) in cultures exposed to CO may suggest a mechanism involving mitochondrial alterations and generation of ROS. In conclusion, the present procedure using controlled, short-term CO exposure allows efficient dopaminergic differentiation of human neural stem cells at low cost and may as such be useful for derivation of cells for experimental studies and future development of donor cells for transplantation in Parkinson's disease.

Photocatalyzing CO2 to CO for Enhanced Cancer Therapy

Continuous exposure to carbon monoxide (CO) can sensitize cancer cells to chemotherapy while protect normal cells from apoptosis. The Janus face of CO thus provides an ideal strategy for cancer therapy. Here, a photocatalytic nanomaterial (HisAgCCN) is introduced to transform endogenous CO₂ to CO for improving cancer therapy in vivo. The CO production rate of HisAgCCN reaches to 65 µmol h^-1 g_mat^-1 , which can significantly increase the cytotoxicity of anticancer drug (doxorubicin, DOX) by 70%. Interestingly, this study finds that HisAgCCN can enhance mitochondria biogenesis and aggravate oxidative stress in cancer cells, whereas protect normal cells from chemotherapy-induced apoptosis as well. Proteomics and metabolomics studies reveal that HisAgCCN can enhance mitochondria biogenesis and aggravate oxidative stress in cancer cells specifically. In vivo studies indicate that HisAgCCN/DOX combination therapy presents a synergetic tumor inhibition, which might provide a new direction for clinical cancer therapy.

Aspects of Carbon Monoxide in Form of CO-Releasing Molecules Used in Cancer Treatment: More Light on the Way

Carbon monoxide (CO) has always been recognised as a toxic gas, due to its higher affinity for haemoglobin than oxygen. However, biological studies have revealed an intriguing role for CO as an endogenous signalling molecule, a gasotransmitter. CO is demonstrated to exert many cellular activities including anti-inflammatory, antiapoptotic, and antiproliferative activities. In animal studies, CO gas administration can prevent tissues from hypoxia or ischemic-reperfusion injury. As a result, there are a plethora of reports dealing with the biological applications of CO and CO-releasing molecules (CORMs) in inflammatory and vascular diseases. CORMs have already been tested as a therapeutic agent in clinical trials. More recently, an increased interest has been drawn to CO's potential use as an anticancer agent. In this review, we will aim to give an overview of the research focused on the role of CO and CORMs in different types of cancer and expand to the recent development of the next generation CORMs for clinical application in cancer treatment.

Sex-dependent alteration of cardiac cytochrome P450 gene expression by doxorubicin in C57Bl/6 mice

BACKGROUND

There is inconclusive evidence about the role of sex as a risk factor for doxorubicin (DOX)-induced cardiotoxicity. Recent experimental studies have shown that adult female rats are protected against DOX-induced cardiotoxicity. However, the mechanisms of this sexual dimorphism are not fully elucidated. We have previously demonstrated that DOX alters the expression of several cytochrome P450 (CYP) enzymes in the hearts of male rats. Nevertheless, the sex-dependent effect of DOX on the expression of CYP enzymes is still not known. Therefore, in the present study, we determined the effect of acute DOX exposure on the expression of CYP genes in the hearts of both male and female C57Bl/6 mice.

METHODS

Acute DOX cardiotoxicity was induced by a single intraperitoneal injection of 20 mg/kg DOX in male and female adult C57Bl/6 mice. Cardiac function was assessed 5 days after DOX exposure by trans-thoracic echocardiography. Mice were euthanized 1 day or 6 days after DOX or saline injection. Thereafter, the hearts were harvested and weighed. Heart sections were evaluated for pathological lesions. Total RNA was extracted and expression of natriuretic peptides, inflammatory and apoptotic markers, and CYP genes was measured by real-time PCR.

RESULTS

Adult female C57Bl/6 mice were protected from acute DOX-induced cardiotoxicity as they show milder pathological lesions, less inflammation, and faster recovery from DOX-induced apoptosis and DOX-mediated inhibition of beta-type natriuretic peptide. Acute DOX exposure altered the gene expression of multiple CYP genes in a sex-dependent manner. In 24 h, DOX exposure caused male-specific induction of Cyp1b1 and female-specific induction of Cyp2c29 and Cyp2e1.

CONCLUSIONS

Acute DOX exposure causes sex-dependent alteration of cardiac CYP gene expression. Since cardiac CYP enzymes metabolize several endogenous compounds to biologically active metabolites, sex-dependent alteration of CYP genes may play a role in the sexual dimorphism of acute DOX-induced cardiotoxicity.

Suppressive effect of exogenous carbon monoxide on endotoxin-stimulated platelet over-activation via the glycoprotein-mediated PI3K-Akt-GSK3β pathway

Platelet activation is an important event involved in the pathophysiological processes of the coagulation system. Clinical evidence has shown that platelets undergo distinctive pathological processes during sepsis. Unfortunately, how platelets physiologically respond to inflammation or sepsis is not well understood. In this study, we used a lipopolysaccharide (LPS)-stimulated platelet model to systemically investigate alterations in membrane glycoprotein expression, molecular signaling, morphology and critical functions of platelets. We found that platelet adhesion, aggregation, secretion, and spreading on immobilized fibrinogen and the expression of platelet membrane glycoproteins were significantly increased by LPS stimulation, and these changes were accompanied by a significant decrease in cGMP levels and an abnormal distribution of platelet α-granules. Exogenous CO reversed these alterations. Profound morphological changes in LPS-stimulated platelets were observed using atomic force microscopy and phase microscopy. Furthermore, the elevated activities of PI3Ks, AKt and GSK-3β were effectively suppressed by exogenous CO, leading to the improvement of platelet function. Together, these results provide evidence that platelet over-activation persists under LPS-stimulation and that exogenous CO plays an important role in suppressing platelet activation via the glycoprotein-mediated PI3K-Akt-GSK3β pathway.

Toward Carbon Monoxide-Based Therapeutics: Critical Drug Delivery and Developability Issues

Carbon monoxide (CO) is an intrinsic signaling molecule with importance on par with that of nitric oxide. During the past decade, pharmacologic studies have amply demonstrated the therapeutic potential of carbon monoxide. However, such studies were mostly based on CO inhalation and metal-based CO-releasing molecules. The field is now at the stage that a major effort is needed to develop pharmaceutically acceptable forms of CO for delivery via various routes such as oral, injection, infusion, or topical applications. This review examines the state of the art, discusses the existing hurdles to overcome, and proposes developmental strategies necessary to address remaining drug delivery issues.

Oxidative Stress and Maxi Calcium-Activated Potassium (BK) Channels

All cells contain ion channels in their outer (plasma) and inner (organelle) membranes. Ion channels, similar to other proteins, are targets of oxidative impact, which modulates ion fluxes across membranes. Subsequently, these ion currents affect electrical excitability, such as action potential discharge (in neurons, muscle, and receptor cells), alteration of the membrane resting potential, synaptic transmission, hormone secretion, muscle contraction or coordination of the cell cycle. In this chapter we summarize effects of oxidative stress and redox mechanisms on some ion channels, in particular on maxi calcium-activated potassium (BK) channels which play an outstanding role in a plethora of physiological and pathophysiological functions in almost all cells and tissues. We first elaborate on some general features of ion channel structure and function and then summarize effects of oxidative alterations of ion channels and their functional consequences.

Carbon monoxide reverses adipose tissue inflammation and insulin resistance upon loss of ovarian function

We hypothesized that carbon monoxide (CO) might suppress chronic inflammation, which led to metabolic disturbances. Ovariectomy (OVX) was performed in mice to mimic chronic inflammation secondary to loss of ovarian function. OVX increased fat mass and the infiltration of highly inflammatory CD11c cells into adipose tissue (AT), resulting in a disturbance of glucose metabolism. Treatment of CO attenuated these; CO decreased recruitment of CD11c-expressing cells in AT and reduced expression of CD11c in bone marrow-derived macrophages, protecting them from M1 polarization. Upregulated cGMP and decreased reactive oxygen species were responsible for the inhibitory activity of CO on CD11c expression; knockdown of soluble guanylate cyclase or heme oxygenase-1 using small interfering RNAs reduced this inhibition substantially. Improved OVX-induced insulin resistance (IR) by CO was highly associated with its activity to attenuate AT inflammation. Our results suggest a therapeutic value of CO to treat postmenopausal IR by reducing AT inflammation.

Boswellic acids synergize antitumor activity and protect against the cardiotoxicity of doxorubicin in mice bearing Ehrlich's carcinoma

This study aimed to test whether boswellic acids add to the antitumor effects of doxorubicin against solid tumors of Ehrlich's ascites carcinoma (EAC) grown in mice, and to investigate the protective effects of boswellic acids against doxorubicin-induced cardiotoxicity. Sixty-four female Swiss albino mice bearing EAC solid tumors were distributed among 8 groups as follows: group 1, EAC control group; group 2, doxorubicin treatment group [mice were injected with doxorubicin (6 mg·(kg body mass)(-1)·week(-1)) for 3 weeks]; groups 3-5, these mice were treated with boswellic acids (125, 250, or 500 mg·kg(-1)·day(-1)), respectively; groups 6-8, these mice were treated with a combination of doxorubicin and boswellic acids (125, 250, or 500 mg·kg(-1)·day(-1)), respectively, for 3 weeks. The results indicated that boswellic acids synergized the antitumor activity of doxorubicin. Doxorubicin-treated mice showed elevated serum activities of lactate dehydrogenase and creatine kinase isoenzyme MB as well as cardiac malondialdehyde. Further, decreases in cardiac levels of reduced glutathione, superoxide dismutase, and catalase activities were observed. These effects were accompanied by an increase in cardiac expression of caspase 3. Thus, treatment with boswellic acids attenuated doxorubicin-evoked disturbances in the above-mentioned parameters, highlighting antioxidant and antiapoptotic activities. Therefore, boswellic acids could be potential candidates for ameliorating the cardiotoxicity of doxorubicin.

Effect of citral on the cytotoxicity of doxorubicin in human B-lymphoma cells

CONTEXT

Doxorubicin is a chemotherapy agent used in non-Hodgkin's lymphoma but side effects limit its use. Citral is a mixture of neral and geranial found in essential oils of lemon grass.

OBJECTIVES

We evaluated the activity of citral, doxorubicin, and combination on cytotoxicity, apoptosis, and anti-proliferative effects using human lymphoma Ramos cells.

MATERIALS AND METHODS

Cells were treated with doxorubicin alone or in combination with citral (10, 20, and 40 μM). Cytotoxic and apoptosis studies were done after 24 and 18 h incubations, respectively. Cytotoxic effects of citral on normal human peripheral blood mononuclear cells (PBMCs) were also investigated for its safety. Changes in the expression of BCL-2 family genes were analyzed by quantitative RT-PCR.

RESULTS

Citral had cytotoxicity on cells with an IC50 value of 77.19 ± 4.95 µM. Citral at concentrations of 10, 20, and 40 µM additively increased the cytotoxic and apoptotic effects of doxorubicin, leading to decreased IC50 (µM) of the drug from 2.50 ± 0.01 to 2.16 ± 0.03, 1.90 ± 0.04, and 1.23 ± 0.04, respectively. Enhanced cytotoxicity was not observed in normal human PBMCs. Citral (40 µM) in combination with doxorubicin (1.5 µM) increased the expression of pro-apoptotic protein BAK but significantly decreased the expression of anti-apoptotic protein BCL-XL to 5.26-fold compared with doxorubicin-treated cells. It did not change the anti-proliferative activity of drug.

DISCUSSION AND CONCLUSION

Citral potentiated cytotoxicity of doxorubicin by increasing apoptotic effects. We conclude that citral may have beneficial effects in patients with B cell lymphoma treated with chemotherapy.

Auxin-induced hydrogen sulfide generation is involved in lateral root formation in tomato

Similar to auxin, hydrogen sulfide (H2S), mainly produced by l-cysteine desulfhydrase (DES; EC 4.4.1.1) in plants, could induce lateral root formation. The objective of this study was to test whether H2S is also involved in auxin-induced lateral root development in tomato (Solanum lycopersicum L.) seedlings. We observed that auxin depletion-induced down-regulation of transcripts of SlDES1, decreased DES activity and endogenous H2S contents, and the inhibition of lateral root formation were rescued by sodium hydrosulfide (NaHS, an H2S donor). However, No additive effects were observed when naphthalene acetic acid (NAA) was co-treated with NaHS (lower than 10 mM) in the induction of lateral root formation. Subsequent work revealed that a treatment with NAA or NaHS could simultaneously induce transcripts of SlDES1, DES activity and endogenous H2S contents, and thereafter the stimulation of lateral root formation. It was further confirmed that H2S or HS(-), not the other sulfur-containing components derived from NaHS, was attributed to the stimulative action. The inhibition of lateral root formation and decreased of H2S metabolism caused by an H2S scavenger hypotaurine (HT) were reversed by NaHS, but not NAA. Molecular evidence revealed that both NaHS- or NAA-induced modulation of some cell cycle regulatory genes, including the up-regulation of SlCDKA;1, SlCYCA2;1, together with simultaneous down-regulation of SlKRP2, were differentially reversed by HT pretreatment. To summarize, above results clearly suggested that H2S might, at least partially, act as a downstream component of auxin signaling to trigger lateral root formation.

Suppressive effect of CORM-2 on LPS-induced platelet activation by glycoprotein mediated HS1 phosphorylation interference

In recent years, it has been discovered that septic patients display coagulation abnormalities. Platelets play a major role in the coagulation system. Studies have confirmed that carbon monoxide (CO) has important cytoprotective and anti-inflammatory function. However, whether CO could alter abnormal activation of platelets and coagulation and thereby reduce the incidence of mortality during sepsis has not been defined. In this report, we have used CO-releasing molecules (CORM-2) to determine whether CO inhibits LPS-induced abnormal activation of platelets and have explored the potential mechanisms. LPS was used to induce activation of platelets in vitro, which were purified from the peripheral venous blood of healthy adult donors. CORM-2 was applied as a potential therapeutic agent. CORM-2 preconditioning and delayed treatment were also studied. We found that in the LPS groups, the function of platelets such as spreading, aggregation, and release were enhanced abnormally. By contrast, the platelets in the CORM-2 group were gently activated. Further studies showed that the expression of platelet membrane glycoproteins increased in the LPS group. Coincidently, both hematopoietic lineage cell-specific protein 1 and its phosphorylated form also increased dramatically. These phenomena were less dramatically seen in the CORM-2 groups. Taken together, we conclude that during LPS stimulation, platelets were abnormally activated, and this functional state may be associated with the signal that is transmitted between membrane glycoproteins and HS1. CORM-released CO suppresses the abnormal activation of platelets by interfering with glycoprotein-mediated HS1 phosphorylation.

Carbon monoxide-based therapy ameliorates acute pancreatitis via TLR4 inhibition

The protective role of hemeoxygenase-1 (HO-1) in various inflammatory conditions is mediated in part by its products, carbon monoxide (CO) and biliverdin. Here we investigated a therapeutic role for CO and CO-primed cells in acute pancreatitis (AP). In a mouse model of AP, treatment with CO-releasing molecule-2 (CORM-2) decreased mortality, pancreatic damage, and lung injury. CORM-2 decreased systemic inflammatory cytokines, suppressed systemic and pancreatic macrophage TNF-α secretion, and inhibited macrophage TLR4 receptor complex expression. In both human and mouse cells, CORM-2 inhibited endogenous and exogenous ligand-dependent TLR4 activation, which indicates that CORM-2 could be therapeutic for both early and late stages of AP, which involve sterile- and endotoxin-mediated inflammation, respectively. Mice engrafted with TLR4-deficient hematopoietic cells were protected against caerulein-induced AP. In the absence of leukocyte TLR4 expression, CORM-2 did not confer additional protection, which indicates that CORM-2-dependent effects are mediated via suppression of macrophage TLR4 activation. We determined that CO was directly responsible for the protective effects of CORM-2 in AP, as inactive forms of CORM-2 were ineffective. Importantly, adoptive transfer of CORM-2-primed cells reduced AP. Such a therapeutic approach would translate the beneficial effects of CO-based therapies, avoiding CO- or CO-RM-mediated toxicities in AP and a wide range of diseases.

Effect of carbon monoxide donor CORM-2 on vitamin D3 metabolism

BACKGROUND/AIMS

Carbon monoxide (CO) interferes with cytochrome-dependent cellular functions and acts as gaseous transmitter. CO is released from CO-releasing molecules (CORM) including tricarbonyl-dichlororuthenium (II) dimer (CORM-2), molecules considered for the treatment of several disorders including vascular dysfunction, inflammation, tissue ischemia and organ rejection. Cytochrome P450-sensitive function include formation of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) by renal 25-hydroxyvitamin D3 1-alpha-hydroxylase (Cyp27b1). The enzyme is regulated by PTH, FGF23 and klotho. 1,25(OH)2D3 regulates Ca(2+) and phosphate transport as well as klotho expression. The present study explored, whether CORM-2 influences 1,25(OH)2D3 formation and klotho expression.

METHODS

Mice were treated with intravenous CORM-2 (20 mg/kg body weight). Plasma 1,25(OH)2D3 and FGF23 concentrations were determined by ELISA, phosphate, calcium and creatinine concentrations by colorimetric methods, transcript levels by quantitative RT-PCR and protein expression by western blotting. Fgf23 mRNA transcript levels were further determined in rat osteosarcoma UMR106 cells without or with prior treatment for 24 hours with 20 µM CORM-2.

RESULTS

CORM-2 injection within 24 hours significantly increased FGF23 plasma levels and decreased 1,25(OH)2D3 plasma levels, renal Cyp27b1 gene expression as well as renal klotho protein abundance and transcript levels. Moreover, treatment of UMR106 cells with CORM-2 significantly increased Fgf23 transcript levels.

CONCLUSION

CO-releasing molecule CORM-2 enhances FGF23 expression and release and decreases klotho expression and 1,25(OH)2D3 synthesis. © 2013 S. Karger AG, Basel.

Cardiac expression of human type 2 iodothyronine deiodinase increases glucose metabolism and protects against doxorubicin-induced cardiac dysfunction in male mice

Altered glucose metabolism in the heart is an important characteristic of cardiovascular and metabolic disease. Because thyroid hormones have major effects on peripheral metabolism, we examined the metabolic effects of heart-selective increase in T3 using transgenic mice expressing human type 2 iodothyronine deiodinase (D2) under the control of the α-myosin heavy chain promoter (MHC-D2). Hyperinsulinemic-euglycemic clamps showed normal whole-body glucose disposal but increased hepatic insulin action in MHC-D2 mice as compared to wild-type (WT) littermates. Insulin-stimulated glucose uptake in heart was not altered, but basal myocardial glucose metabolism was increased by more than two-fold in MHC-D2 mice. Myocardial lipid levels were also elevated in MHC-D2 mice, suggesting an overall up-regulation of cardiac metabolism in these mice. The effects of doxorubicin (DOX) treatment on cardiac function and structure were examined using M-mode echocardiography. DOX treatment caused a significant reduction in ventricular fractional shortening and resulted in more than 50% death in WT mice. In contrast, MHC-D2 mice showed increased survival rate after DOX treatment, and this was associated with a six-fold increase in myocardial glucose metabolism and improved cardiac function. Myocardial activity and expression of AMPK, GLUT1, and Akt were also elevated in MHC-D2 and WT mice following DOX treatment. Thus, our findings indicate an important role of thyroid hormone in cardiac metabolism and further suggest a protective role of glucose utilization in DOX-mediated cardiac dysfunction.

Carbon monoxide releasing molecules inhibit cell death resulting from renal transplantation related stress

PURPOSE

Organ cold storage and subsequent transplantation are associated with significant ischemia-reperfusion injury, leading to cell death, graft inflammation and decreased graft function.

MATERIALS AND METHODS

CORM-3s reduce oxidative stress and prevent inflammation in kidneys stored at 4C and subsequently transplanted. Graft survival and function are markedly improved compared to kidneys preserved and stored in University of Wisconsin solution alone. We determined whether CORM-3 has direct antiapoptotic effects on in vitro preparations of human HUVECs exposed to anoxic conditions. We also determined whether direct administration of CORM-3 to renal grafts before and/or after cold storage would prevent renal damage during the transplantation process.

RESULTS

CORM-3 supplementation led to a significantly increased frequency of live cells (mean ± SD 72.3% ± 1.9%, p <0.01), reduced apoptosis (14.9% ± 6.1%, p <0.01) and decreased mitochondrial transmembrane potential (40.2% ± 7.2%, p <0.05) in HUVECs exposed to 20 hours of cold storage compared to controls (11.6% ± 3.5%, 82.2% ± 2.3% and 78.2% ± 3.2%, respectively). In keeping with this antiapoptotic effect CORM-3 supplementation led to a mean 7.4 ± 2.1-fold up-regulation in Bcl-2 gene expression. CORM-3 supplementation in standard preservation solution was most beneficial at initial ischemic injury and before cold storage exposure. However, additional reflushing before vascular reperfusion showed an additive benefit to graft survival and function after transplantation. This was confirmed by decreased glomerular and tubular necrosis, and apoptosis in double flushed grafts.

CONCLUSIONS

CORM-3 supplementation in standard University of Wisconsin solution has a significant impact on decreasing cellular and graft injury, and improving survival through its antiapoptotic effects, which are likely mediated through mitochondrial membrane stabilization.

Carbon monoxide improves cardiac function and mitochondrial population quality in a mouse model of metabolic syndrome

AIMS

Metabolic syndrome induces cardiac dysfunction associated with mitochondria abnormalities. As low levels of carbon monoxide (CO) may improve myocardial and mitochondrial activities, we tested whether a CO-releasing molecule (CORM-3) reverses metabolic syndrome-induced cardiac alteration through changes in mitochondrial biogenesis, dynamics and autophagy.

METHODS AND RESULTS

Mice were fed with normal diet (ND) or high-fat diet (HFD) for twelve weeks. Then, mice received two intraperitoneal injections of CORM-3 (10 mg x kg(-1)), with the second one given 16 hours after the first. Contractile function in isolated hearts and mitochondrial parameters were evaluated 24 hours after the last injection. Mitochondrial population was explored by electron microscopy. Changes in mitochondrial dynamics, biogenesis and autophagy were assessed by western-blot and RT-qPCR. Left ventricular developed pressure was reduced in HFD hearts. Mitochondria from HFD hearts presented reduced membrane potential and diminished ADP-coupled respiration. CORM-3 restored both cardiac and mitochondrial functions. Size and number of mitochondria increased in the HFD hearts but not in the CORM-3-treated HFD group. CORM-3 modulated HFD-activated mitochondrial fusion and biogenesis signalling. While autophagy was not activated in the HFD group, CORM-3 increased the autophagy marker LC3-II. Finally, ex vivo experiments demonstrated that autophagy inhibition by 3-methyladenine abolished the cardioprotective effects of CORM-3.

CONCLUSION

CORM-3 may modulate pathways controlling mitochondrial quality, thus leading to improvements of mitochondrial efficiency and HFD-induced cardiac dysfunction.

Carbon monoxide-sensitive apoptotic death of erythrocytes

Carbon monoxide (CO) intoxication severely interferes with the oxygen-transporting function of haemoglobin. Beyond that, CO participates in the regulation of apoptosis. CO could be generated from CO-releasing molecules (CORM), such as the tricarbonyl-dichlororuthenium (II) dimer (CORM-2), which is presently considered for the treatment of vascular dysfunction, inflammation, tissue ischaemia and organ rejection. CORM-2 is at least partially effective by modifying gene expression and mitochondrial potential. Erythrocytes lack nuclei and mitochondria but may undergo suicidal cell death or eryptosis, characterized by cell shrinkage and phospholipid scrambling of the cell membrane. Eryptosis is triggered by the increase in cytosolic Ca²⁺ activity ([Ca²⁺](i)). The present study explored whether CORM-2 influences eryptosis. To this end, [Ca²⁺](i) was estimated from Fluo-3-fluorescence, cell volume from forward scatter, phospholipid scrambling from annexin-V-binding and haemolysis from haemoglobin release. CO-binding haemoglobin (COHb) was estimated utilizing a blood gas analyser. As a result, exposure of erythrocytes for 24 hr to CORM-2 (≥5 μM) significantly increased COHb, [Ca²⁺](i) , forward scatter, annexin-V-binding and haemolysis. Annexin-V-binding was significantly blunted by 100% oxygen and was virtually abolished in the nominal absence of Ca²⁺. In conclusion, CORM-2 stimulates cell membrane scrambling of erythrocytes, an effect largely due to Ca²⁺ entry and partially reversed by O₂.

Carbon monoxide: an unusual drug

The highly toxic gas carbon monoxide (CO) displays many physiological roles in several organs and tissues. Although many diseases, including cancer, hematological diseases, hypertension, heart failure, inflammation, sepsis, neurodegeneration, and sleep disorders, have been linked to abnormal endogenous CO metabolism and functions, CO administration has therapeutic potential in inflammation, sepsis, lung injury, cardiovascular diseases, transplantation, and cancer. Here, insights into the CO-based therapy, characterized by the induction or gene transfer of heme oxygenase-1 and either gas or CO-releasing molecule administration, are reviewed.