Endogenous Carbon Monoxide Production Research Articles

A long-wavelength mitochondria-targeted CO fluorescent probe for living cells and zebrafish imaging.

Carbon monoxide (CO) not only causes damage to life and health as an environmental pollutant, but also undertakes many physiological functions in organisms. In particular, developing means that can be used for the determination of CO in organelles will provide insight into the vital role it plays. Studies have shown that mitochondrial respiration is closely related to CO concentrations, so it is critical to develop tools for CO detection in mitochondria. Here, we use a rhodamine derivative that can target mitochondria as fluorophores to construct a mitochondrial-labeled CO fluorescence probe (Rh-CO) with high sensitivity (detection limit: 9.4 nM), excellent water-solubility, and long emission (λem = 630 nm). Prominently, the probe has outstanding mitochondria-targeting capabilities. Moreover, we used transient glucose deprivation (TGD) and heme to stimulate endogenous CO production in living cells and zebrafish, respectively, and the probe exhibited excellent imaging capabilities. All in all, we expect this probe to contribute to a deeper understanding of the role played by CO in mitochondria.

Carboxyhemoglobin as a diagnostic and prognostic biomarker of hemolytic anemias in dogs.

Endogenous production of carbon monoxide during hemoglobin metabolism leads to the formation of carboxyhemoglobin. Carboxyhemoglobin concentration is abnormally high in humans with hemolytic anemia (HA). Measurement of carboxyhemoglobin concentration can discriminate HA from other forms of anemia. Twenty-seven dogs with HA (immune-mediated HA, n=22; microangiopathic HA, n=5), 27 dogs with non-HA (kidney disease, n=14; immune-mediated thrombocytopenia, [n=6]; miscellaneous, n=7) and 24 nonanemic control dogs. Prospective cohort study. Carboxyhemoglobin quantification, a CBC and biochemistry profile were performed upon admission, and survival to hospital discharge and at 30 days were the measured outcomes. Groups were compared by the Mann-Whitney and Kruskal-Wallis tests. Receiver-operator characteristic (ROC) analyses were used to examine the predictive utility of carboxyhemoglobin for the diagnosis of HA in anemic dogs. Carboxyhemoglobin (median [interquartile range]) differed between dogs with HA (7.7% [2.5%]) and non-HA (3.6% [1.05]; P < .001) and dogs with HA and nonanemic dogs (3.5% [0.65%]; P < .001). No difference was detected between nonHA and nonanemic dogs. The area under the ROC curve for carboxyhemoglobin as predictor of HA in anemic dogs was 0.997 (95% CI, 0.99-1.00). Three optimal cut-off points were identified, including 5.05%, 4.55% and 4.85%, with corresponding sensitivity/specificity of 92.6%/100%, 100%/92.6% and 96.3%/96.3%, respectively. Neither carboxyhemoglobin nor any of the CBC or chemistry analytes were associated with survival. Carboxyhemoglobin proved an excellent predictor of HA in dogs and might constitute a useful, ancillary tool for diagnosing and monitoring hemolytic anemias.

Continuous Endogenous Exhaled CO Monitoring by Laser Spectrometer in Human EVLP Before Lung Transplantation.

Endogenous production of carbon monoxide (CO) is affected by inflammatory phenomena and ischemia-reperfusion injury. Precise measurement of exhaled endogenous CO (eCO) is possible thanks to a laser spectrometer (ProCeas® from AP2E company). We assessed eCO levels of human lung grafts during the normothermic Ex-Vivo Lung Perfusion (EVLP). ProCeas® was connected in bypass to the ventilation circuit. The surgical team took the decision to transplant the lungs without knowing eCO values. We compared eCO between accepted and rejected grafts. EVLP parameters and recipient outcomes were also compared with eCO values. Over 7 months, eCO was analyzed in 21 consecutive EVLP grafts. Two pairs of lungs were rejected by the surgical team. In these two cases, there was a tendency for higher eCO values (0.358 ± 0.52 ppm) compared to transplanted lungs (0.240 ± 0.76 ppm). During the EVLP procedure, eCO was correlated with glucose consumption and lactate production. However, there was no association of eCO neither with edema formation nor with the PO2/FiO2 ratio per EVLP. Regarding post-operative data, every patient transplanted with grafts exhaling high eCO levels (>0.235 ppm) during EVLP presented a Primary Graft Dysfunction score of 3 within the 72 h post-transplantation. There was also a tendency for a longer stay in ICU for recipients with grafts exhaling high eCO levels during EVLP. eCO can be continuously monitored during EVLP. It could serve as an additional and early marker in the evaluation of the lung grafts providing relevant information for post-operative resuscitation care.

Моніторинг вмісту в крові карбоксигемоглобіну для оцінки тяжкості травматичного шоку та реперфузійних ушкоджень (аналітичний огляд з результатами власних спостережень)

Монооксид вуглецю — природний метаболіт організму. В організмі СО утворюється в процесі роботи ферменту гемоксигенази 1 та 2 із зруйнованого гемоглобіну. Цей процес зумовлює утворення деякої кількості карбоксигемоглобіну у здорових осіб, навіть якщо СО не надходить до організму ззовні в процесі дихання. СО виконує функції сигнальної молекули, модулюючи стан тонусу серцево-судинної системи, пригнічує та сприяє зворотному розвитку порушень, що викликані запальною відповіддю, та може відігравати важливу роль як потенційний терапевтичний агент. З іншого боку, СО при взаємодії з гемоглобіном утворює карбоксигемоглобін та витісняє кисень із зв’язки з гемоглобіном, що веде до неспроможності доставки кисню тканинам. Окрім цього, СО також зв’язується із міоглобіном та мітохондріальною цитохромоксидазою. Тривала присутність у крові значної кількості СО викликає серйозні ушкодження міокарда та центральної нервової системи. Отже, надмірна ендогенна продукція СО та надмірне утворення карбоксигемоглобіну можуть відігравати значну роль у тканинному пошкодженні та формуванні поліорганної дисфункції. Окрім гему, що звільнюється при руйнуванні гемоглобіну, джерелом продукції ендогенного СО та, у свою чергу, карбоксигемоглобіну можуть бути компоненти зруйнованих клітинних мембран та мітохондріальні ферменти, що містять гем. Клітинні ушкодження, що мають місце в умовах травматичного шоку, наслідки ішемії/реперфузії, геморагічне просочення тканин, гемотрансфузії та інтенсивне утворення агресивних вільних радикалів ведуть до зазначених подій. На сьогодні більшість дослідників розглядає продукцію СО та карбоксигемоглобіну при критичних станах як компенсаторний механізм, що забезпечує цитопротекцію та зростання виживаності хворих. Ми вивчили результати досліджень, що стосуються оцінки інтенсивності продукції СО, вмісту в крові карбоксигемоглобіну та вмісту СО в повітрі, що видихається, у пацієнтів в критичних станах та порівняли ці результати із даними власних спостережень. В іноземних джерелах наведено концентрації карбоксигемоглобіну в крові, що в більшості випадків не перевищували 4 %. У нашому дослідженні вивчались пацієнти із політравмою та крововтратою на ранньому госпітальному етапі. Оцінювалися показники центральної гемодинаміки, а також сатурація капілярної крові киснем, перфузійний індекс та вміст у крові карбоксигемоглобіну за допомогою технології компанії «Masimo». Усі постраждалі надходили до клініки з нормальним вмістом карбоксигемоглобіну в крові. Патологічне зростання концентрації карбоксигемоглобіну спостерігалося в процесі реперфузії. Швидка рідинна ресусцитація, застосування гіпертонічних розчинів та адреналіну сприяли зростанню артеріального тиску, перфузійного індексу та концентрації карбоксигемоглобіну. Наступне за реперфузією зростання концентрації в крові карбоксигемоглобіну було тим більшим, чим більш тяжким був перебіг шоку. Реінфузія крові також сприяла збільшенню концентрації карбоксигемоглобіну в крові. Високі показники концентрації карбоксигемоглобіну в крові постраждалих із травматичним шоком у період реперфузії закономірно викликають питання про його роль у формуванні мітохондріальної дисфункції при травматичній хворобі.

Carbon Monoxide in Renal Physiology, Pathogenesis and Treatment of Renal Disease.

Carbon monoxide (CO) is one of the endogenous gaseous messengers or gasotransmitters, and is a paramount mediator in physiological and disease conditions. In this review, we focus on the functions of CO in normal and pathological renal physiology. We discuss endogenous renal CO production and signaling in the normal kidney, the characteristic of CO-releasing molecules (CORMs) modalities, and outline its regulatory functions in renal physiology. This article summarizes the mechanisms as well as the effect of CO in the evolving field of renal diseases. We predict numerous innovative CO applications forevolvingcutting-edge scholarly work in the future.

Ontogeny of Carbon Monoxide-Related Gene Expression in a Deep-Diving Marine Mammal.

Marine mammals such as northern elephant seals (NES) routinely experience hypoxemia and ischemia-reperfusion events to many tissues during deep dives with no apparent adverse effects. Adaptations to diving include increased antioxidants and elevated oxygen storage capacity associated with high hemoprotein content in blood and muscle. The natural turnover of heme by heme oxygenase enzymes (encoded by HMOX1 and HMOX2) produces endogenous carbon monoxide (CO), which is present at high levels in NES blood and has been shown to have cytoprotective effects in laboratory systems exposed to hypoxia. To understand how pathways associated with endogenous CO production and signaling change across ontogeny in diving mammals, we measured muscle CO and baseline expression of 17 CO-related genes in skeletal muscle and whole blood of three age classes of NES. Muscle CO levels approached those of animals exposed to high exogenous CO, increased with age, and were significantly correlated with gene expression levels. Muscle expression of genes associated with CO production and antioxidant defenses (HMOX1, BVR, GPX3, PRDX1) increased with age and was highest in adult females, while that of genes associated with protection from lipid peroxidation (GPX4, PRDX6, PRDX1, SIRT1) was highest in adult males. In contrast, muscle expression of mitochondrial biogenesis regulators (PGC1A, ESRRA, ESRRG) was highest in pups, while genes associated with inflammation (HMOX2, NRF2, IL1B) did not vary with age or sex. Blood expression of genes involved in regulation of inflammation (IL1B, NRF2, BVR, IL10) was highest in pups, while HMOX1, HMOX2 and pro-inflammatory markers (TLR4, CCL4, PRDX1, TNFA) did not vary with age. We propose that ontogenetic upregulation of baseline HMOX1 expression in skeletal muscle of NES may, in part, underlie increases in CO levels and expression of genes encoding antioxidant enzymes. HMOX2, in turn, may play a role in regulating inflammation related to ischemia and reperfusion in muscle and circulating immune cells. Our data suggest putative ontogenetic mechanisms that may enable phocid pups to transition to a deep-diving lifestyle, including high baseline expression of genes associated with mitochondrial biogenesis and immune system activation during postnatal development and increased expression of genes associated with protection from lipid peroxidation in adulthood.

First Report of Red Blood Cell Lifespan in a Marine Mammal: An Insight Into Endogenous Carbon Monoxide (CO) Production

Deep-diving marine mammals are known to have high concentrations of hemoglobin (Hb), experience hypoxemia from extended breath-holds, and ischemia-reperfusion events in tissues from the physiological dive response. However, certain deep-diving seals (e.g., elephant and Weddell seals) are known to have levels of carbon monoxide (CO) in their blood that are similar to those seen in chronic cigarette smokers (>10% carboxyhemoglobin; COHb). The source of the high CO in the seals is currently unknown. The gas is naturally produced in humans and lab animals as a byproduct of heme degradation, by heme oxygenase enzymes. Therefore, CO production is tightly correlated with red blood cell (RBC) lifespan and associated Hb degradation, as shown by higher COHb (average 1.9%, maximum 9.7%) in patients with shortened RBC lifespans due to hemolytic anemia. Although normally considered a toxic gas, low levels of CO are naturally produced in most mammals (≤ 1% COHb in healthy humans), and exposure to moderate concentrations of exogenous CO has shown to elicit cytoprotective effects (e.g., anti-inflammation) in tissues exposed to hypoxia or ischemia-reperfusion events. Therefore, there is a desire to ascertain the mechanisms behind the regulation of elevated CO in marine mammals. Similar to humans, the production of high concentrations of CO in marine mammals is hypothesized to be directly related to their RBC lifespan. The RBC lifespan has been determined in a variety of terrestrial vertebrates, but never reported for any marine mammal species. In terrestrial mammals, there is an allometric relationship with larger animals having longer RBC lifespans (RBC lifespan (days) = (body mass (kg)0.132) (68) + 49). This study reports the first measurements of RBC lifespan in a marine mammal, the shallow-diving bottlenose dolphin (mass = 216 ± 23 kg, Hb = 14 g/dl). We hypothesize that the bottlenose dolphin would have a RBC lifespan that is similar to healthy humans (~120 days). Our results show the RBC lifespan of the bottlenose dolphin is 165.7 ± 18.4 days. Like humans, bottlenose dolphins also had low levels of CO in their blood (1.6 ± 0.5 % COHb) and exhaled breath (2.4 ± 1.0 ppm). Ongoing measurements in larger, deeper-diving mammals (e.g., beluga whales, 747 ± 244 kg, Hb = 21 g/dl), will further reveal the impact of heme stores and body mass on RBC lifespan and endogenous CO production in mammals.

Endogenous Carbon Monoxide Production and Diffusing Capacity of the Lung for Carbon Monoxide in Sepsis-Induced Acute Respiratory Distress Syndrome.

Low-dose inhaled carbon monoxide is a novel therapeutic under investigation in acute respiratory distress syndrome. The Coburn-Forster-Kane equation is a well-validated model of carbon monoxide uptake that can accurately predict carboxyhemoglobin levels to ensure safe administration of low-dose inhaled carbon monoxide in patients with acute respiratory distress syndrome. Using data from a Phase I trial of low-dose inhaled carbon monoxide, we performed a post hoc analysis to determine if the Coburn-Forster-Kane equation could be used to assess the diffusing capacity of the lung for carbon monoxide and endogenous carbon monoxide production in patients with sepsis-induced acute respiratory distress syndrome. Diffusing capacity of the lung for carbon monoxide was substantially reduced and correlated with Pao2/Fio2 and Sequential Organ Failure Assessment score. Endogenous carbon monoxide production was markedly elevated and was significantly associated with Lung Injury Score in sepsis-induced acute respiratory distress syndrome patients. Our data suggest that the Coburn-Forster-Kane equation can be used to estimate diffusing capacity of the lung for carbon monoxide and endogenous carbon monoxide production in mechanically ventilated patients. We found that increased endogenous carbon monoxide production and reduced diffusing capacity of the lung for carbon monoxide correlate with clinical endpoints associated with outcomes in patients with sepsis-induced acute respiratory distress syndrome.

Ligand-Directed Approach to Activity-Based Sensing: Developing Palladacycle Fluorescent Probes That Enable Endogenous Carbon Monoxide Detection.

Carbon monoxide (CO) is an emerging gasotransmitter and reactive carbon species with broad anti-inflammatory, cytoprotective, and neurotransmitter functions along with therapeutic potential for the treatment of cardiovascular diseases. The study of CO chemistry in biology and medicine relative to other prominent gasotransmitters such as NO and H2S remains challenging, in large part due to limitations in available tools for the direct visualization of this transient and freely diffusing small molecule in complex living systems. Here we report a ligand-directed activity-based sensing (ABS) approach to CO detection through palladium-mediated carbonylation chemistry. Specifically, the design and synthesis of a series of ABS probes with systematic alterations in the palladium-ligand environment (e.g., sp3-S, sp3-N, sp2-N) establish structure-activity relationships for palladacycles to confer selective reactivity with CO under physiological conditions. These fundamental studies led to the development of an optimized probe, termed Carbon Monoxide Probe-3 Ester Pyridine (COP-3E-Py), which enables imaging of CO release in live cell and brain settings, including monitoring of endogenous CO production that triggers presynaptic dopamine release in fly brains. This work provides a unique tool for studying CO in living systems and establishes the utility of a synthetic methods approach to activity-based sensing using principles of organometallic chemistry.

Endogenous Carbon Monoxide Signaling Modulates Mitochondrial Function and Intracellular Glucose Utilization: Impact of the Heme Oxygenase Substrate Hemin.

Stress-inducible heme oxygenase-1 (HO-1) catalyzes the oxidative cleavage of heme yielding biliverdin, ferrous iron, and carbon monoxide (CO). Heme oxygenase activity has been attributed to antioxidant defense via the redox cycling system of biliverdin and bilirubin. There is increasing evidence that CO is a gaseous signaling molecule and plays a role in the regulation of energy metabolism. Inhibitory effects of CO on the respiratory chain are well established, but the implication of such a process on the cellular stress response is not well understood. By means of extracellular flux analyses and isotopic tracing, we studied the effects of CO, either released from the CO donor CORM-401 or endogenously produced by heme oxygenases, on the respiratory chain and glucose metabolism. CORM-401 was thereby used as a tool to mimic endogenous CO production by heme oxygenases. In the long term (>60 min), CORM-401-derived CO exposure inhibited mitochondrial respiration, which was compensated by increased glycolysis accompanied by a loss of the ATP production rate and an increase in proton leakage. This effect pattern was likewise observed after endogenous CO production by heme oxygenases. However, in the present setting, these effects were only observed when sufficient substrate for heme oxygenases (hemin) was provided. Modulation of the HO-1 protein level was less important. The long-term influence of CO on glucose metabolism via glycolysis was preceded by a short-term response (<30 min) of the cells to CO. Stable isotope-labeling experiments and metabolic flux analysis revealed a short-term shift of glucose consumption from glycolysis to the pentose phosphate pathway (PPP) along with an increase in reactive oxygen species (ROS) generation. Overall, we suggest that signaling by endogenous CO stimulates the rapid formation of reduction equivalents (NADPH) via the PPP, and plays an additional role in antioxidant defense, e.g., via feed-forward stimulation of the bilirubin/biliverdin redox cycling system.

Carbon Monoxide Being Hydrogen Sulfide and Nitric Oxide Molecular Sibling, as Endogenous and Exogenous Modulator of Oxidative Stress and Antioxidative Mechanisms in the Digestive System.

Oxidative stress reflects an imbalance between oxidants and antioxidants in favor of the oxidants capable of evoking tissue damage. Like hydrogen sulfide (H2S) and nitric oxide (NO), carbon monoxide (CO) is an endogenous gaseous mediator recently implicated in the physiology of the gastrointestinal (GI) tract. CO is produced in mammalian tissues as a byproduct of heme degradation catalyzed by the heme oxygenase (HO) enzymes. Among the three enzymatic isoforms, heme oxygenase-1 (HO-1) is induced under conditions of oxidative stress or tissue injury and plays a beneficial role in the mechanism of protection against inflammation, ischemia/reperfusion (I/R), and many other injuries. According to recently published data, increased endogenous CO production by inducible HO-1, its delivery by novel pharmacological CO-releasing agents, or even the direct inhalation of CO has been considered a promising alternative in future experimental and clinical therapies against various GI disorders. However, the exact mechanisms underlying behind these CO-mediated beneficial actions are not fully explained and experimental as well as clinical studies on the mechanism of CO-induced protection are awaited. For instance, in a variety of experimental models related to gastric mucosal damage, HO-1/CO pathway and CO-releasing agents seem to prevent gastric damage mainly by reduction of lipid peroxidation and/or increased level of enzymatic antioxidants, such as superoxide dismutase (SOD) or glutathione peroxidase (GPx). Many studies have also revealed that HO-1/CO can serve as a potential defensive pathway against oxidative stress observed in the liver and pancreas. Moreover, increased CO levels after treatment with CO donors have been reported to protect the gut against formation of acute GI lesions mainly by the regulation of reactive oxygen species (ROS) production and the antioxidative activity. In this review, we focused on the role of H2S and NO molecular sibling, CO/HO pathway, and therapeutic potential of CO-releasing pharmacological tools in the regulation of oxidative stress-induced damage within the GI tract with a special emphasis on the esophagus, stomach, and intestines and also two solid and important metabolic abdominal organs, the liver and pancreas.

Lactate Dehydrogenase to Carboxyhemoglobin Ratio As a Biomarker of Heme Release to Heme Processing Is Associated with Higher Tricuspid Regurgitant Jet Velocity and Early Death in Sickle Cell Disease

Background Chronic hemolysis is a hallmark of sickle cell disease (SCD). Intravascular hemolysis in particular is associated with severe vasculopathic complications including pulmonary hypertension (PH) and early mortality. Free heme causes oxidative damage and recently was identified as erythrocyte-derived Danger Associated Molecular Pattern (e-DAMP), associated with endothelial activation and vaso-occlusion in SCD (Belcher et al., Blood. 2014; Ghosh et al., J. Clin. Invest. 2013). Intravascular hemolysis is associated with elevated levels of serum lactate dehydrogenase (LDH). Heme catabolism leads to endogenous carbon monoxide (CO) production by heme oxygenase-1 (HO1), and CO is eliminated in exhaled breath. CO is transported primarily as the conjugate carboxyhemoglobin (HbCO), and end-alveolar CO (EACO) is an accepted proxy marker for its concentration in blood. We evaluated several lab values and ratios that might reflect the relative contribution of intravascular heme release and overall heme processing. Methods We investigated the relationship between EACO, HbCO (NCT01547793, cohort A) and other biomarkers of hemolysis in adults with SCD at steady state as part of the clinical cohort at the National Institutes of Health Clinical Center, Bethesda, Maryland, USA (NCT00011648, cohort B). Of the patients included in the cohort B, all routine samples with results on HbCO were included in the analyses. In a subgroup of the cohort B with data available on HbCO, echocardiography and/or mortality, we evaluated the correlation between LDH/HbCO ratio and echocardiographic markers of PH and all-cause mortality (cohort C). Combining all recognized available markers for hemolysis (total bilirubin, AST, absolute reticulocyte count, hemoglobin, median LDH, median HbCO and LDH/HbCO ratio) in a multivariate Cox proportional hazards model for survival led to selection of a predictive model encompassing three biomarkers: LD/HbCO ratio, AST and hemoglobin. Of these three markers, the LD/HbCO ratio was the most predictive factor. We also conducted univariate correlations with clinical outcome indicators. Main findings Erythropoietic and hemolytic laboratory parameters of the cohorts are provided in Table 1. HbCO concentrations and EACO were strongly correlated (Pearson's correlation r=0.66, p&lt;0.01). In both cohort A and cohort B, HbCO and EACO were not correlated to LDH. However, EACO and HbCO did correlate with absolute reticulocyte counts (respectively r=0.46, p&lt;0.01 and r=0.58, p&lt;0.01). The patients of cohort C were divided into low (peak TRV &lt;2.5m/s, N=34), intermediate (peak TRV 2.5-3m/s, N=38) and high risk (peak TRV &gt;=3.0m/s, N=13) categories, based upon prior cut-points determined by risk of development of PH and early mortality (Mehari A. et al. JAMA. 2012) (Figure 1, panel A). LDH/HbCO ratios were positively correlated with TRV (r=0.38, p&lt;0.01), and were significantly higher in patients with TRV &gt;=3.0m/s (Mann-Whitey U test; p=0.02). In contrast, LDH values alone were not discriminative. All patients (25/25) with a LDH/HbCO ratio &lt;1,200 had a TRV &lt;3.0m/s; 94% (15/16) of the patients with catheterization-proven PH had a LDH/HbCO ratio &gt;1,200. In the intermediate risk subgroup, PH was only diagnosed in individuals with LDH/HbCO ratios exceeding 1,200. Median follow-up was 12.1 years (IQR 10.3; 16.3), 25% (23/91) of the patients died during follow-up. Five-year, 10-year and 15-year overall survival in the group with LDH/HbCO ratio &gt;1,200 were respectively 92.1%, 76.0% and 69.1%, whereas 5-year, 10-year and 15-year overall survival in the group with LDH/HbCO ratio &lt;1,200 were respectively 100%, 92.9% and 88.0% (Figure 1, panel B). LDH/HbCO ratios were associated with all-cause mortality in a Cox proportional hazards model (p&lt;0.01) and remained significantly associated with all-cause mortality when adjusted for age, C-reactive protein and ferritin (p=0.02). LDH alone was not associated with all-cause mortality in the unadjusted analysis. Main conclusions A ratio of two readily available clinical laboratory markers, LDH and HbCO, is promising as a potential biomarker in SCD. Increased LDH/HbCO ratios are strongly associated with elevated TRV and all-cause mortality, and thereby might improve the individual risk prediction in SCD patients. These markers deserve additional validation in future prospective trials. Disclosures van Wijk: Agios Pharmaceuticals: Consultancy, Research Funding; RR Mechatronics: Research Funding. Minniti:Doris Duke Foundation: Research Funding. Kato:Novartis, Global Blood Therapeutics: Consultancy, Research Funding; Bayer: Research Funding. van Beers:Novartis: Consultancy, Research Funding; Pfizer: Research Funding; RR Mechatronics: Research Funding; Agios Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Підвищення ендогенної продукції монооксиду вуглецю та утворення небезпечного вмісту в крові карбоксигемоглобіну в пацієнтів з політравмою, які перебувають у критичних станах

Підвищення ендогенної продукції монооксиду вуглецю та утворення небезпечного вмісту в крові карбоксигемоглобіну в пацієнтів з політравмою, які перебувають у критичних станах

Endogenous carbon monoxide production by menadione

IntroductionSmokers have a significantly decreased risk of pre-eclampsia (PE), possibly attributed to an increase in blood carbon monoxide (CO) concentrations. At physiological concentrations, CO has been demonstrated to have placental vasodilatory and anti-inflammatory properties. Increasing endogenous CO production may have therapeutic potential to either prevent or treat PE. Menadione (MD), synthetic vitamin K3, increases CO in rat microsomes. Our objective was to investigate MD's ability to increase endogenous CO concentrations in pregnancy. MethodsThree experiments were completed. First, in vitro CO production was measured using isolated GD15 placentas. Second, non-pregnant normotensive mice received no, 1.5, 4.0 or 6.5 g/L MD for 7 days. Lastly, pregnant normotensive mice received either no or 6.5 g/L MD in water from GD10.5 to GD17.5. Consumption was measured as average daily water intake per gram of body weight. Maternal and fetal CO levels in the blood and tissue were quantified using headspace gas chromatography. ResultsMD significantly increased CO production in isolated GD15 placentas. In both pregnant and non-pregnant experiments, splenic CO, hepatic CO, and splenic mass were higher in treated mice compared to controls (all p < 0.05). Maternal %COHb and Hb in treated dams were not significantly different compared to controls. The fetal:placental mass ratio was significantly lower in the treatment group (p = 0.002). DiscussionPlacental CO production was observed in GD15 placentas after co-incubation with MD. MD administration increased CO in the liver and spleens of pregnant mice. Further investigation into different doses of MD is required to identify one without demonstrable fetal/placental effects.

Circadian clock disruption by selective removal of endogenous carbon monoxide

Circadian rhythms are regulated by transcription-translation feedback loops (TTFL) of clock genes. Previous studies have demonstrated that core transcriptional factors, NPAS2 and CLOCK, in the TTFL can reversibly bind carbon monoxide (CO) in vitro. However, little is known about whether endogenous CO, which is continuously produced during a heme metabolic process, is involved in the circadian system. Here we show that selective removal of endogenous CO in mice considerably disrupts rhythmic expression of the clock genes. A highly selective CO scavenger, hemoCD1, which is a supramolecular complex of an iron(II)porphyrin with a per-O-methyl-β-cyclodextrin dimer, was used to remove endogenous CO in mice. Intraperitoneal administration of hemoCD1 to mice immediately reduced the amount of internal CO. The removal of CO promoted the bindings of NPAS2 and CLOCK to DNA (E-box) in the murine liver, resulting in up-regulation of the E-box-controlled clock genes (Per1, Per2, Cry1, Cry2, and Rev-erbα). Within 3 h after the administration, most hemoCD1 in mice was excreted in the urine, and heme oxygenase-1 (HO-1) was gradually induced in the liver. Increased endogenous CO production due to the overexpression of HO-1 caused dissociation of NPAS2 and CLOCK from E-box, which in turn induced down-regulation of the clock genes. The down-regulation continued over 12 h even after the internal CO level recovered to normal. The late down-regulation was ascribed to an inflammatory response caused by the endogenous CO reduction. The CO pseudo-knockdown experiments provided the clear evidence that endogenous CO contributes to regulation in the mammalian circadian clock.

Role of Carbon Monoxide in Neurovascular Repair Processing.

Carbon monoxide (CO) is a gaseous molecule produced from heme by heme oxygenase (HO). Endogenous CO production occurring at low concentrations is thought to have several useful biological roles. In mammals, especially humans, a proper neurovascular unit comprising endothelial cells, pericytes, astrocytes, microglia, and neurons is essential for the homeostasis and survival of the central nervous system (CNS). In addition, the regeneration of neurovascular systems from neural stem cells and endothelial precursor cells after CNS diseases is responsible for functional repair. This review focused on the possible role of CO/HO in the neurovascular unit in terms of neurogenesis, angiogenesis, and synaptic plasticity, ultimately leading to behavioral changes in CNS diseases. CO/HO may also enhance cellular networks among endothelial cells, pericytes, astrocytes, and neural stem cells. This review highlights the therapeutic effects of CO/HO on CNS diseases involved in neurogenesis, synaptic plasticity, and angiogenesis. Moreover, the cellular mechanisms and interactions by which CO/HO are exploited for disease prevention and their therapeutic applications in traumatic brain injury, Alzheimer’s disease, and stroke are also discussed.

Role of endogenous carbon monoxide in the control of breathing in zebrafish (Danio rerio).

Carbon monoxide (CO) is a gaseous signaling molecule and is produced in vivo from the intracellular breakdown of heme via the heme oxygenase (HO) family of enzymes. In this study we investigated the role of the HO-1/CO system in the control of ventilation in zebrafish, Danio rerio Immunohistochemistry revealed the presence of HO-1 in the chemoreceptive neuroepithelial cells (NECs) of larvae (4 days postfertilization) and adults, indicating the potential for endogenous CO production in the NECs. Hypoxia (20 min, water Po2 of 30 mmHg) caused a significant increase in HO-1 activity in whole larvae and in the gills of adult fish. Zebrafish with reduced HO-1 activity (via HO-1 knockdown in larvae or zinc protoporphyrin IX treatment in adults) exhibited increased ventilation frequency (Vf) under normoxic but not hypoxic conditions. The addition of exogenous CO restored resting Vf in fish with diminished CO production, and in some cases (e.g., hypoxic sham larvae) CO modestly reduced Vf below resting levels. Larval fish were treated with phenylhydrazine (PHZ) to eliminate the potential confounding effects of CO-hemoglobin interactions that might influence ventilation. PHZ treatment did not cause changes in Vf of normoxic larvae, and the addition of CO to PHZ-exposed larvae resulted in a significant decrease in sham and HO-1-deficient fish under normoxic conditions. This study demonstrates for the first time that CO plays an inhibitory role in the control of breathing in larval and adult zebrafish.

Determinants of Carboxyhemoglobin Levels and Relationship with Sepsis in a Retrospective Cohort of Preterm Neonates.

Carboxyhemoglobin levels in blood reflect endogenous carbon monoxide production and are often measured during routine blood gas analysis. Endogenous carbon monoxide production has been reported to be increased during sepsis, but carboxyhemoglobin levels have not been thoroughly evaluated as a biomarker of sepsis. We sought to determine whether carboxyhemoglobin levels were elevated during sepsis in a high risk population of premature neonates. We conducted a retrospective cohort study of 30 infants in two neonatal intensive care units using electronic medical and laboratory records. The majority of infants were extremely premature and extremely low birth weight, and 25 had at least one episode of sepsis. We collected all carboxyhemoglobin measurements during their in-patient stay and examined the relationship between carboxyhemoglobin and a variety of clinical and laboratory parameters, in addition to the presence or absence of sepsis, using linear mixed-effect models. We found that postnatal age had the most significant effect on carboxyhemoglobin levels, and other significant associations were identified with gestational age, hemoglobin concentration, oxyhemoglobin saturation, and blood pH. Accounting for these covariates, there was no significant relationship between the onset of sepsis and carboxyhemoglobin levels. Our results show that carboxyhemoglobin is unlikely to be a clinically useful biomarker of sepsis in premature infants, and raise a note of caution about factors which may confound the use of carbon monoxide as a clinical biomarker for other disease processes such as hemolysis.

Feedback Response to Selective Depletion of Endogenous Carbon Monoxide in the Blood.

The physiological roles of endogenous carbon monoxide (CO) have not been fully understood because of the difficulty in preparing a loss-of-function phenotype of this molecule. Here, we have utilized in vivo CO receptors, hemoCDs, which are the supramolecular 1:1 inclusion complexes of meso-tetrakis(4-sulfonatophenyl)porphinatoiron(II) with per-O-methylated β-cyclodextrin dimers. Three types of hemoCDs (hemoCD1, hemoCD2, and hemoCD3) that exhibit different CO-affinities have been tested as CO-depleting agents in vivo. Intraperitoneally administered hemoCD bound endogenous CO within the murine circulation, and was excreted in the urine along with CO in an affinity-dependent manner. The sufficient administration of hemoCD that has higher CO-affinity than hemoglobin (Hb) produced a pseudoknockdown state of CO in the mouse in which heme oxygenase-1 (HO-1) was markedly induced in the liver, causing the acceleration of endogenous CO production to maintain constant CO-Hb levels in the blood. The contents of free hemin and bilirubin in the blood plasma of the treated mice significantly increased upon removal of endogenous CO by hemoCD. Thus, a homeostatic feedback model for the CO/HO-1 system was proposed as follows: HemoCD primarily removes CO from cell-free CO-Hb. The resulting oxy-Hb is quickly oxidized to met-Hb by oxidant(s) such as hydrogen peroxide in the blood plasma. The met-Hb readily releases free hemin that directly induces HO-1 in the liver, which metabolizes the hemin into iron, biliverdin, and CO. The newly produced CO binds to ferrous Hb to form CO-Hb as an oxidation-resistant state. Overall, the present system revealed the regulatory role of CO for maintaining the ferrous/ferric balance of Hb in the blood.

A Functional Coupling Between Carbon Monoxide and Nitric Oxide Contributes to Increased Vasopressin Neuronal Activity in Heart Failure rats.

Despite the pathophysiological importance of neurohumoral activation in patients with heart failure (HF), the precise underlying mechanisms contributing to elevated vasopressin (VP) activation in HF remains unknown. Carbon monoxide (CO) is a gaseous neurotransmitter in the central nervous system that stimulates VP neuronal firing activity. Recently, we showed that the excitatory effect of CO on VP neurons in the hypothalamic paraventricular nucleus (PVN) was mediated by inhibition of nitric oxide (NO). Given that previous studies showed that VP neuronal activity is enhanced, whereas NO inhibitory signaling is blunted in HF rats, we tested whether an enhanced endogenous CO availability within the PVN contributes to elevated VP neuronal activity and blunted NO signaling in HF rats. We found that both haeme-oxygenase 1 (the CO-synthesizing enzyme) protein and mRNA expression levels were enhanced in the PVN of HF compared with sham rats (∼18% and ∼38%, respectively). We report that in sham rats, bath application of a CO donor (tricarbonyldichlororuthenium dimer) increased the firing activity of identified PVN VP neurons (P < .05), whereas inhibition of endogenous CO production (Tin-protoporphyrin IX [SnPP]) failed to affect neuronal activity. In HF rats, however, SnPP decreased VP activity (P < .05), an effect that was occluded by previous NO synathase blockade NG-nitro-larginine methyl ester. Finally, we found that SnPP increased the mean frequency of γ-aminobutyric acid inhibitory postsynaptic currents in VP neurons in HF (P < .05) but not sham rats. Our results support an enhanced endogenous CO excitatory signaling in VP neurons, which likely contributes to blunted NO and γ-aminobutyric acid inhibitory function in HF rats.