The CO-releasing molecule CORM-3 protects adult cardiomyocytes against hypoxia-reoxygenation by modulating pH restoration

Carbon monoxide-releasing molecule-3 ameliorates traumatic brain injury-induced cardiac dysfunctions via inhibition of pyroptosis and apoptosis

Traumatic brain injury (TBI) frequently results in cardiac dysfunction and impacts the quality of survivors' life. It has been reported that carbon monoxide-releasing molecule-3 (CORM-3) administration immediately after hemorrhagic shock and resuscitation (HSR) ameliorated the HSR‑induced cardiac dysfunctions. The purpose of this study was to determine whether the application of CORM-3 on TBI exerted therapeutic effects against TBI-induced cardiac dysfunctions. Rats were randomly divided into four groups (n = 12) including Sham, TBI, TBI/CORM-3 and TBI/inactive CORM-3 (iCORM-3) groups. TBI was established by a weight-drop model. The rats in the TBI/CORM-3 group and TBI/iCORM-3 group were intravenously injected with CORM-3 and iCORM-3 (4 mg/kg) following TBI, respectively. The time of death in the rats that did not survive within 24 h was recorded. 24 h post-trauma, the cardiac function, pathological change, serum troponin T and creatine kinase-MB (CK-MB) levels, pyroptosis, apoptosis and expressions of TUNEL staining, Gasdermin D (GSDMD), IL-1β, IL-18, ratio Bax/Bcl-2 were assessed by echocardiography, hematoxylin-eosin staining, chemiluminescence, immunofluorescence, and western blot assays, respectively. TBI-treated rats exhibited dramatically decreased ejection fraction and aggravated myocardial injury, increased mortality rate, elevated levels of serum troponin T and CK-MB, promoted cardiac pyroptosis and apoptosis, and upregulated expressions of cleaved caspase-3, GSDMD N-terminal fragments, IL-1β, IL-18, and ratio of Bax/Bcl-2, whereas CORM-3 partially reversed these changes. CORM-3 ameliorated TBI-induced cardiac injury and dysfunction. This mechanism may be responsible for the inhibition of pyroptosis and apoptosis in cardiomyocyte.

Inhibitors of NLRP3 Inflammasome Formation: A Cardioprotective Role for the Gasotransmitters Carbon Monoxide, Nitric Oxide, and Hydrogen Sulphide in Acute Myocardial Infarction

Myocardial ischaemia reperfusion injury (IRI) occurring from acute coronary artery disease or cardiac surgical interventions such as bypass surgery can result in myocardial dysfunction, presenting as, myocardial "stunning", arrhythmias, infarction, and adverse cardiac remodelling, and may lead to both a systemic and a localised inflammatory response. This localised cardiac inflammatory response is regulated through the nucleotide-binding oligomerisation domain (NACHT), leucine-rich repeat (LRR)-containing protein family pyrin domain (PYD)-3 (NLRP3) inflammasome, a multimeric structure whose components are present within both cardiomyocytes and in cardiac fibroblasts. The NLRP3 inflammasome is activated via numerous danger signals produced by IRI and is central to the resultant innate immune response. Inhibition of this inherent inflammatory response has been shown to protect the myocardium and stop the occurrence of the systemic inflammatory response syndrome following the re-establishment of cardiac circulation. Therapies to prevent NLRP3 inflammasome formation in the clinic are currently lacking, and therefore, new pharmacotherapies are required. This review will highlight the role of the NLRP3 inflammasome within the myocardium during IRI and will examine the therapeutic value of inflammasome inhibition with particular attention to carbon monoxide, nitric oxide, and hydrogen sulphide as potential pharmacological inhibitors of NLRP3 inflammasome activation.

Gasotransmitters and noble gases in cardioprotection: unraveling molecular pathways for future therapeutic strategies

Despite recent progress, ischemic heart disease poses a persistent global challenge, driving significant morbidity and mortality. The pursuit of therapeutic solutions has led to the emergence of strategies such as ischemic preconditioning, postconditioning, and remote conditioning to shield the heart from myocardial ischemia/reperfusion injury (MIRI). These ischemic conditioning approaches, applied before, after, or at a distance from the affected organ, inspire future therapeutic strategies, including pharmacological conditioning. Gasotransmitters, comprising nitric oxide, hydrogen sulfide, sulfur dioxide, and carbon monoxide, play pivotal roles in physiological and pathological processes, exhibiting shared features such as smooth muscle relaxation, antiapoptotic effects, and anti-inflammatory properties. Despite potential risks at high concentrations, physiological levels of gasotransmitters induce vasorelaxation and promote cardioprotective effects. Noble gases, notably argon, helium, and xenon, exhibit organ-protective properties by reducing cell death, minimizing infarct size, and enhancing functional recovery in post-ischemic organs. The protective role of noble gases appears to hinge on their modulation of molecular pathways governing cell survival, leading to both pro- and antiapoptotic effects. Among noble gases, helium and xenon emerge as particularly promising in the field of cardioprotection. This overview synthesizes our current understanding of the roles played by gasotransmitters and noble gases in the context of MIRI and cardioprotection. In addition, we underscore potential future developments involving the utilization of noble gases and gasotransmitter donor molecules in advancing cardioprotective strategies.

Carbon monoxide as a cellular protective agent in a swine model of cardiac arrest protocol

Out-of-hospital cardiac arrest (OHCA) affects over 360,000 adults in the United States each year with a 50-80% mortality prior to reaching medical care. Despite aggressive supportive care and targeted temperature management (TTM), half of adults do not live to hospital discharge and nearly one-third of survivors have significant neurologic injury. The current treatment approach following cardiac arrest resuscitation consists primarily of supportive care and possible TTM. While these current treatments are commonly used, mortality remains high, and survivors often develop lasting neurologic and cardiac sequela well after resuscitation. Hence, there is a critical need for further therapeutic development of adjunctive therapies. While select therapeutics have been experimentally investigated, one promising agent that has shown benefit is CO. While CO has traditionally been thought of as a cellular poison, there is both experimental and clinical evidence that demonstrate benefit and safety in ischemia with lower doses related to improved cardiac/neurologic outcomes. While CO is well known for its poisonous effects, CO is a generated physiologically in cells through the breakdown of heme oxygenase (HO) enzymes and has potent antioxidant and anti-inflammatory activities. While CO has been studied in myocardial infarction itself, the role of CO in cardiac arrest and post-arrest care as a therapeutic is less defined. Currently, the standard of care for post-arrest patients consists primarily of supportive care and TTM. Despite current standard of care, the neurological prognosis following cardiac arrest and return of spontaneous circulation (ROSC) remains poor with patients often left with severe disability due to brain injury primarily affecting the cortex and hippocampus. Thus, investigations of novel therapies to mitigate post-arrest injury are clearly warranted. The primary objective of this proposed study is to combine our expertise in swine models of CO and cardiac arrest for future investigations on the cellular protective effects of low dose CO. We will combine our innovative multi-modal diagnostic platform to assess cerebral metabolism and changes in mitochondrial function in swine that undergo cardiac arrest with therapeutic application of CO.

Carbon Monoxide Releasing Molecule-3 Alleviates Oxidative Stress and Apoptosis in Selenite-Induced Cataract in Rats via Activating Nrf2/HO-1 Pathway

PURPOSE

This study investigated the protective effect of carbon monoxide releasing molecule-3 (CORM-3), the classical donor of carbon monoxide, on selenite-induced cataract in rats and explore its possible mechanism.

METHODS

Sprague-Dawley rat pups treated with sodium selenite (Na2SeO3) were chosen as the cataract model. Fifty rat pups were randomly divided into 5 groups: Control group, Na2SeO3 (3.46 mg/kg) group, low-dose CORM-3 (8 mg/kg/d) + Na2SeO3 group, high-dose CORM-3 (16 mg/kg/d) + Na2SeO3 group, and inactivated CORM-3 (iCORM-3) (8 mg/kg/d) + Na2SeO3 group. The protective effect of CORM-3 was tested by lens opacity scores, hematoxylin and eosin staining, TdT-mediated dUTP nick-end labeling assay, and enzyme-linked immunosorbent assay. Besides, quantitative real-time PCR and western blotting were used for mechanism validation.

RESULTS

Na2SeO3 induced nuclear cataract rapidly and stably, and the achievement ratio of Na2SeO3 group was 100%. CORM-3 alleviated lens opacity of selenite-induced cataract and attenuated the morphological changes of the rat lens. The levels of antioxidant enzymes GSH and SOD in rat lens were also increased by CORM-3 treatment. CORM-3 significantly reduced the ratio of apoptotic lens epithelial cells, besides, CORM-3 decreased the expression of Cleaved Caspase-3 and Bax induced by selenite and increased the expression of Bcl-2 in rat lens inhibited by selenite. Moreover, Nrf-2 and HO-1 were upregulated and Keap1 was downregulated after CORM-3 treatment. While iCORM-3 did not exert the same effect as CORM-3.

CONCLUSIONS

Exogenous CO released from CORM-3 alleviates oxidative stress and apoptosis in selenite-induced rat cataract via activating Nrf2/HO-1 pathway. CORM-3 may serve as a promising preventive and therapeutic strategy for cataract.

Controlled therapeutic delivery of CO from carbon monoxide-releasing molecules (CORMs)

Carbon monoxide (CO) has been regarded as a "silent killer" for its toxicity toward biological systems. However, a low concentration of endogenously produced CO has shown a number of therapeutic benefits such as anti-inflammatory, anti-proliferative, anti-apoptosis, and cytoprotective activities. Carbon monoxide-releasing molecules (CORMs) have been developed as alternatives to direct CO inhalation, which requires a specialized setting for strict dose control. CORMs are efficient CO donors, with central transition metals (such as ruthenium, iron, cobalt, and manganese) surrounded by CO as a ligand. CORMs can stably store and subsequently release their CO payload in the presence of certain triggers including solvent, light, temperature, and ligand substitution. However, CORMs require appropriate delivery strategies to improve short CO release half-life and target specificity. Herein, we highlighted the therapeutic potential of inhalation and CORMs-delivered CO. The applications of conjugate and nanocarrier systems for controlling CO release and improving therapeutic efficacy of CORMs are also described in detail. The review concludes with some of the hurdles that limit clinical translation of CORMs. Keeping in mind the tremendous potential and growing interest in CORMs, this review would be helpful for designing controlled CO release systems for clinical applications.

CORM-3 Attenuates Oxidative Stress-Induced Bone Loss via the Nrf2/HO-1 Pathway

Bone metabolism occurs in the entire life of an individual and is required for maintaining skeletal homeostasis. The imbalance between osteogenesis and osteoclastogenesis eventually leads to osteoporosis. Oxidative stress is considered a major cause of bone homeostasis disorder, and relieving excessive oxidative stress in bone mesenchymal stem cells (BMSCs) is a potential treatment strategy for osteoporosis. Carbon monoxide releasing molecule-3 (CORM-3), the classical donor of carbon monoxide (CO), possesses antioxidation, antiapoptosis, and anti-inflammatory properties. In our study, we found that CORM-3 could reduce reactive oxygen species (ROS) accumulation and prevent mitochondrial dysfunction thereby restoring the osteogenic potential of the BMSCs disrupted by hydrogen peroxide (H₂O₂) exposure. The action of CORM-3 was preliminarily considered the consequence of Nrf2/HO-1 axis activation. In addition, CORM-3 inhibited osteoclast formation in mouse primary bone marrow monocytes (BMMs) by inhibiting H₂O₂-induced polarization of M1 macrophages and endowing macrophages with M2 polarizating ability. Rat models further demonstrated that CORM-3 treatment could restore bone mass and enhance the expression of Nrf2 and osteogenic markers in the distal femurs. In summary, CORM-3 is a potential therapeutic agent for the treatment of osteoporosis.

Ratiometric Fluorescent pH Sensor Based on a Tunable Multivariate Covalent Organic Framework

Ratiometric detection of pH is always significant in environmental regulation, medical diagnosis, synthetic chemistry, and beyond. The construction of practical ratiometric pH sensors with reusability is still challenging. Herein, by exploiting a multivariate strategy, we first synthesized and reported a series of novel three-component covalent organic frameworks (COF-COOH_X, X = 33, 50, and 67) through Schiff base reaction between 2-hydroxybenzene-1,3,5-tricarbaldehyde (HTA), 4,4'-diamino-3,3'-biphenyldicarboxylic acid (DBA), and 5,5'-diamino-2,2'-bipyridine (BPY) at various molar ratios (X = [DBA]/([BPY] + [DBA]) × 100 = 33, 50, and 67). COF-COOH_X (X = 33, 50, and 67) displayed ratiometric pH sensing performance in acidic conditions with selectivity and repeatability. By tuning the molar ratio of DBA and BPY, the fluorescent properties, linear pH responsive ranges, and pK_a values of COF-COOH_X (X = 33, 50, and 67) can be regulated. Meanwhile, the two-component COF-COOH₀ and COF-COOH₁₀₀ did not exhibit ratiometric pH detection ability. Moreover, the constructed three ratiometric sensors can be applied to detect pH in drug solutions and carbonated drinks with satisfactory results. This work sheds new light on the design and fabrication of innovative ratiometric fluorescent sensors using COFs.

Functional Regulation of KATP Channels and Mutant Insight Into Clinical Therapeutic Strategies in Cardiovascular Diseases

ATP-sensitive potassium channels (K_ATP channels) play pivotal roles in excitable cells and link cellular metabolism with membrane excitability. The action potential converts electricity into dynamics by ion channel-mediated ion exchange to generate systole, involved in every heartbeat. Activation of the K_ATP channel repolarizes the membrane potential and decreases early afterdepolarization (EAD)-mediated arrhythmias. K_ATP channels in cardiomyocytes have less function under physiological conditions but they open during severe and prolonged anoxia due to a reduced ATP/ADP ratio, lessening cellular excitability and thus preventing action potential generation and cell contraction. Small active molecules activate and enhance the opening of the K_ATP channel, which induces the repolarization of the membrane and decreases the occurrence of malignant arrhythmia. Accumulated evidence indicates that mutation of K_ATP channels deteriorates the regulatory roles in mutation-related diseases. However, patients with mutations in K_ATP channels still have no efficient treatment. Hence, in this study, we describe the role of K_ATP channels and subunits in angiocardiopathy, summarize the mutations of the K_ATP channels and the functional regulation of small active molecules in K_ATP channels, elucidate the potential mechanisms of mutant K_ATP channels and provide insight into clinical therapeutic strategies.

Carbon monoxide and a change of heart

The relationship between carbon monoxide and the heart has been extensively studied in both clinical and preclinical settings. The Food and Drug Administration (FDA) is keenly focused on the ill effects of carbon monoxide on the heart when presented with proposals for clinical trials to evaluate efficacy of this gasotransmitter in a various disease settings. This review provides an overview of the rationale that examines the actions of the FDA when considering clinical testing of CO, and contrast that with the continued accumulation of data that clearly show not only that CO can be used safely, but is potently cardioprotective in clinically relevant small and large animal models. Data emerging from Phase I and Phase II clinical trials argues against CO being dangerous to the heart and thus it needs to be redefined and evaluated as any other substance being proposed for use in humans. More than twenty years ago, the belief that CO could be used as a salutary molecule was ridiculed by experts in physiology and medicine. Like all agents designed for use in humans, careful pharmacology and safety are paramount, but continuing to hinder progress based on long-standing dogma in the absence of data is improper. Now, CO is being tested in multiple clinical trials using innovative delivery methods and has proven to be safe. The hope, based on compelling preclinical data, is that it will continue to be evaluated and ultimately approved as an effective therapeutic.

Application of carbon monoxide in kidney and heart transplantation: A novel pharmacological strategy for a broader use of suboptimal renal and cardiac grafts

Carbon monoxide (CO) was historically regarded solely as a poisonous gas that binds to hemoglobin and reduces oxygen-carrying capacity of blood at high concentrations. However, recent findings show that it is endogenously produced in mammalian cells as a by-product of heme degradation by heme oxygenase, and has received a significant attention as a medical gas that influences a myriad of physiological and pathological processes. At low physiological concentrations, CO exhibits several therapeutic properties including antioxidant, anti-inflammatory, anti-apoptotic, anti-fibrotic, anti-thrombotic, anti-proliferative and vasodilatory properties, making it a candidate molecule that could protect organs in various pathological conditions including cold ischemia-reperfusion injury (IRI) in kidney and heart transplantation. Cold IRI is a well-recognized and complicated cascade of interconnected pathological pathways that poses a significant barrier to successful outcomes after kidney and heart transplantation. A substantial body of preclinical evidence demonstrates that CO gas and CO-releasing molecules (CO-RMs) prevent cold IRI in renal and cardiac grafts through several molecular and cellular mechanisms. In this review, we discuss recent advances in research involving the use of CO as a novel pharmacological strategy to attenuate cold IRI in preclinical models of kidney and heart transplantation through its administration to the organ donor prior to organ procurement or delivery into organ preservation solution during cold storage and to the organ recipient during reperfusion and after transplantation. We also discuss the underlying molecular mechanisms of cyto- and organ protection by CO during transplantation, and suggest its clinical use in the near future to improve long-term transplantation outcomes.

Carbon monoxide activates large-conductance calcium-activated potassium channels of human cardiac fibroblasts through various mechanisms

Carbon monoxide (CO) is a cardioprotectant and potential cardiovascular therapeutic agent. Human cardiac fibroblasts (HCFs) are important determinants of myocardial structure and function. Large-conductance Ca²⁺-activated K⁺ (BK) channel is a potential therapeutic target for cardiovascular disease. We investigated whether CO modulates BK channels and the signaling pathways in HCFs using whole-cell mode patch-clamp recordings. CO-releasing molecules (CORMs; CORM-2 and CORM-3) significantly increased the amplitudes of BK currents (IBK). The CO-induced stimulating effects on IBK were blocked by pre-treatment with specific nitric oxide synthase (NOS) blockers (L-N^G-monomethyl arginine citrate and L-N^G-nitroarginine methyl ester). 8-bromo-cyclic GMP increased IBK. KT5823 (inhibits PKG) or ODQ (inhibits soluble guanylate cyclase) blocked the CO-stimulating effect on IBK. Moreover, 8-bromo-cyclic AMP also increased IBK, and pre-treatment with KT5720 (inhibits PKA) or SQ22536 (inhibits adenylate cyclase) blocked the CO effect. Pre-treatment with N-ethylmaleimide (a thiol-alkylating reagent) also blocked the CO effect on IBK, and DL-dithiothreitol (a reducing agent) reversed the CO effect. These data suggest that CO activates IBK through NO via the NOS and through the PKG, PKA, and S-nitrosylation pathways.

The effects of carbon monoxide releasing molecules on paraquat-induced pulmonary interstitial inflammation and fibrosis

Paraquat, an herbicide used extensively worldwide, can cause severe toxicity in humans and animals, leading to irreversible, lethal lung fibrosis. The potential of CO-releasing molecules (CORMs), substances that release CO (Carbon monoxide) within animal tissues, for treating paraquat-induced ROS generation and inflammation is investigated here. Our results show that the fast CO releaser CORM-3 (4-20 μM) acts as a potential scavenger of free radicals and decreases fibrosis progression by inhibiting paraquat-induced overexpression of connective tissue growth factor and angiotensin II in MRC-5 cells. The slow CO releaser CORM-A1 (5 mg/kg) clearly decreased expression of the lung profibrogenic cytokines COX-2, TNF-α, and α-SMA and serum hydroxyproline, resulting in a lower mortality rate in paraquat-treated mice. Mice treated with higher-dose CORM-A1 (10 mg/kg) had relatively intact lung lobes and fewer fibrotic patches by gross observation, with less collagen deposition, mesangial matrix accumulation, and pulmonary fibrosis resulting from the mitigation of TGF-β overexpression. In conclusion, our data demonstrate for the first time that CORM-A1 alleviated the development of the fibrotic process and improved survival rate in mice exposed to PQ, would be an attractive therapeutic approach to attenuate the progression of pulmonary fibrosis following PQ exposure.

Estrogen-Mediated Gaseous Signaling Molecules in Cardiovascular Disease

Gender difference is well recognized as a key risk factor for cardiovascular disease (CVD). Estrogen, the primary female sex hormone, improves cardiovascular functions through receptor (ERα, ERβ, or G protein-coupled estrogen receptor)-initiated genomic or non-genomic mechanisms. Gaseous signaling molecules, including nitric oxide (NO), hydrogen sulfide (H₂S), and carbon monoxide (CO), are important regulators of cardiovascular function. Recent studies have demonstrated that estrogen regulates the production of these signaling molecules in cardiovascular cells to exert its cardiovascular protective effects. We discuss current understanding of gaseous signaling molecules in cardiovascular disease (CVD), the underlying mechanisms through which estrogen exerts cardiovascular protective effects by regulating these molecules, and how these findings can be translated to improve the health of postmenopausal women.

Carbon Monoxide-Releasing Molecule-3 Suppresses Tumor Necrosis Factor-α- and Interleukin-1β-Induced Expression of Junctional Molecules on Human Gingival Fibroblasts via the Heme Oxygenase-1 Pathway

Human gingival fibroblast barrier dysfunction caused by inflammation contributes to gingivitis and can lead to inflammatory periodontal disease. The disease features include upregulated epithelial permeability, increased inflammatory mediators, and downregulated junctional complex molecules. Carbon monoxide- (CO-) releasing molecule-3 (CORM-3) is a water-soluble compound that has demonstrated anti-inflammatory effects in in vitro and in vivo studies. In this study, we aimed to investigate the effects of CORM-3 on the expression of tight and adherens junction molecules on human gingival fibroblasts (HGFs) stimulated with tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). HGFs were cultured from the explants of normal human gingival tissues, which were stimulated in the presence or absence of CORM-3. Epithelial barrier function was evaluated by paracellular permeability and junctional complex molecule expression analyses. The protein and mRNA expression levels of adherens junction molecules (VE-cadherin and β-catenin) and tight junction molecules (zona occludens-1, ZO-1) were studied using western blot analysis and reverse transcription-quantitative polymerase chain reaction (RT-PCR). The mRNA and protein expression levels of these cytokines were also analyzed in HGFs transiently transfected with HO-1 small interfering RNA (siRNA) in response to TNF-α and IL-1β stimulation. CORM-3 reduced permeability and enhanced the expression of junctional complex molecules (ZO-1, VE-cadherin, and β-catenin) in TNF-α- and IL-1β-induced HGFs. However, these effects of CORM-3 were attenuated when HO-1 siRNA was transiently transfected in HGFs. These findings indicate that CORM-3 exerts anti-inflammatory effects on TNF-α- and IL-1β-stimulated HGFs via the HO-1 pathway, which suggests the promising potential of CORM-3 in the treatment of inflammatory periodontal disease.