The endothelium is important for the regulation of vascular tone. In diseases like hypertension, the endothelial cells become dysfunctional. This dysfunction is characterized by nitric oxide (NO) deficiency, impairment of endothelium-dependent hyperpolarization (EDH) and the overwhelming production of endothelium-derived contracting factor (EDCF). Heme oxygenase (HO) is the rate-limiting enzyme in the catabolism of heme, producing carbon monoxide(CO), bilirubin and free iron. Up-regulation of the inducible isoform (HO-1) of the enzyme lowers blood pressure in animals. The purpose of the present study was to investigate whether or not up-regulation of HO-1by the pharmacological agent hemin improves endothelial function in arteries of spontaneously hypertensive rats(SHR). Twenty four hours after intraperitoneal injection of hemin (50mg/kg) in 36 weeks old SHR, the expression and activity of HO-1 were augmented, in both the endothelium and vascular smooth muscle. Hemin-treatment potentiated endothelium-dependent relaxations to the muscarinic agonist acetylcholine in both the aorta and the mesenteric artery, whereas the HO inhibitor protoporphyrin IX zinc (II) (ZnPP; 30 mg/kg) prevented the beneficial effect of hemin, suggesting that HO-1 induction improves endothelial function. Hemin-treatment did not augment acetylcholine-induced NO-mediated relaxations, and did not alter the expression level of either phosphorylated eNOS (Ser1177) or total eNOS, suggesting that the improvement of endothelial function by HO-1 induction cannot be attributed to an increased bioavailability of NO. In the mesenteric arteries, hemin treatment potentiated acetylcholine-evoked EDH-mediated relaxations in the presence of L-NAME and indomethacin. The IKCa channel blocker TRAM-34andthe Na+-K+-ATPase blocker ouabain significantly impaired these hemin-potentiated relaxations. NS309-induced TRAM-34-and ouabain-sensitive relaxations were enhanced by hemin-treatment. K+-induced ouabain-sensitive relaxations and the expression of Na+-K+-ATPase were increased by hemin-treatment. Taken in conjunction, these observations imply that the improved EDH-mediated relaxations by HO-1 induction is due to an improvement of IKCa-Na+-K+-ATPase pathway. Treatment with an antioxidant apocynin (50mg/kg) showed a similar effect as hemin, and the combined treatment with hemin and apocynin did not cause a greater improvement. In vitro treatment with bilirubin, enhanced EDH responses and K+-induced ouabain-sensitive relaxations. These observations suggest that the effect of HO-1 induction on EDH-mediated relaxations is possibly due to its antioxidant properties and the production of bilirubin. In the aortae, hemin-treatment reduced endothelium-dependent contractions in response to acetylcholineor to a calcium ionophoreA23187. Production of reactive oxygen species (ROS) was suppressed by hemin-treatment, judging from the results of 2’,7’-dichlorodihydrofluoresein diacetate staining, dihydroethidium staining and lucigenin chemiluminescence, which was attributed to the decreased expressions of NADPH oxidase-2 (Nox2) and cyclooxygenase-1(COX-1). The production of prostacyclin was decreased, which was explained by a lower expression of COX-1. Contractions to vasoconstrictor concentrations of prostacyclin and its mimetic iloprost were attenuated, suggesting that the responsiveness of thromboxane-prostanoid receptors (TP receptors) to prostacyclin was decreased by hemin-treatment. The effects of HO-1 on the suppressed production of ROS and prostacyclin, and the decreased responsiveness of TP receptors, contribute to its inhibitory role on EDCF-mediated response. Thus, up-regulation of HO-1 improves endothelial function in the SHR by potentiating EDH response and impairing EDCF. / published_or_final_version / Pharmacology and Pharmacy / Doctoral / Doctor of Philosophy

Background/Objective: Reperfusion injury is a serious consequence of blood flow reestablishment after myocardial infarction (MI) mediated by reactive oxygen species and neutrophilic cellular damage. Following MI, the left ventricle (LV) undergoes remodeling characterized by progressive wall thinning and cavity dilatation. Heme-Oxygenase-1 (HO-1) dependent decrease in oxidative stress may attenuate injury in part by inhibiting transcription factor NFκB-mediated inflammation. Hypothesis: I hypothesized that upregulation of HO-1 by hemin administration confers acute and chronic cardioprotection against I/R injury in rats and attenuates LV remodeling post-MI. I proposed the HO-1-dependent decrease in oxidative stress attenuates post-ischemic myocardial injury in part by inhibiting NFκB-mediated inflammation. Methods: Six week old male Wistar rats were randomly assigned to sham, vehicle, or hemin-treated groups. Vehicle and hemin were administered intraperitoneally once daily for 3 consecutive days prior to left anterior descending (LAD) coronary artery occlusion. Administration resumed 48 hours post-operatively and continued once every 3 days. Infarct size was determined by H&E histological analysis and fibrosis was quantified by Masson’s Trichrome staining. Transthoracic echocardiography was used to assess LV parameters and wall motion. Results: Hemin increased HO-1 expression, decreased infarct size and fibrosis, and attenuated LV remodeling in the short-term (4 days post-infarction). The decrease in infarct size and area of fibrosis in the hemin group was accompanied by a decrease in NFκB activity. No significant difference in infarct size and area of fibrosis between hemin and vehicle-treated groups was observed at 3 months. LV diameter and cardiac function did not differ significantly between the two groups at 3 months despite an attenuation of anterior wall thinning in the hemin group. Conclusion: HO-1 upregulation by hemin administration conferred acute cardioprotection and attenuated LV remodeling, possibly by inhibiting NFκB-mediated inflammation. However, chronic treatment with hemin did not prevent long-term post-infarction LV remodeling. It is possible that cardioprotection afforded by HO-1 upregulation is strong enough to curtail inflammation post-reperfusion and prevent LV remodeling acutely, but is not robust enough to protect the myocardium to the same degree in the long-term. Future research should focus on optimal HO-1 upregulation to attenuate long-term LV remodeling due to reperfusion injury. / Thesis (Master, Physiology) -- Queen's University, 2007-09-25 19:01:33.87

Abstract Previous studies have examined stress-induced heme oxygenase-1 (HO-1) expression primarily in mammalian systems. The present study examines, for the first time in amphibians, the effect of heat shock, sodium arsenite, cadmium chloride, and the proteasomal inhibitor MG132 on HO-1 accumulation in Xenopus laevis A6 kidney epithelial cells. Western blot analysis revealed that exposure of A6 cells to a range of heat shock temperatures (30-35 °C), which induced HSP30 accumulation, did not induce HO-1 accumulation. In contrast, cells treated with sodium arsenite (5-50 μM), cadmium chloride (50-200 μM) or MG132 (5-30 μM) exhibited a dose- and time-dependent accumulation of HO-1. Additionally, immunocytochemical analysis revealed that HO-1 and HSP30 accumulation occurred in a granular pattern primarily in the cytoplasm in cells treated with sodium arsenite, cadmium chloride, or MG132. In cells recovering from sodium arsenite or cadmium chloride treatment, HO-1 and HSP30 accumulation initially increased to a maximum at 12 h and 24 h recovery, respectively, followed by a 50% reduction at 48 h. This initial increase in the relative levels of stress proteins was likely the result of new synthesis as it was inhibited by cycloheximide. In comparison, cells recovering from MG132 treatment displayed reduced but prolonged accumulation of HO-1 and HSP30. Interestingly, cells treated with low concentrations (10 μM) of sodium arsenite or MG132 but not cadmium chloride in combination with a mild 30 °C heat shock had enhanced accumulation of HO-1 and HSP30 accumulation compared to either of the stressors individually. This study has shown for the first time in amphibians that HO-1 accumulation is induced in response to metals and proteasomal inhibitors, suggesting that it may play a role in mediating the cellular stress response in X. laevis.

Preeclampsia (PE) is a maternal disorder of pregnancy, characterized by late-onset hypertension and proteinuria. It affects roughly 5-7% of all pregnancies worldwide and is a leading cause of maternal and fetal/neonatal morbidity and mortality. Cigarette smoking in pregnancy is associated with a 33% reduction in the incidence of PE, and this is dose dependent. It is hypothesized that carbon monoxide (CO), a combustion product in cigarettes, may confer cytoprotective and regulatory properties leading to the decreased incidence of PE. CO is produced endogenously by the enzyme heme oxygenase (HO), and it is thought that the manipulation of the HO/CO system in pregnancy can ameliorate or reduce the pathophysiologic signs of PE. The exposure of pregnant mice to 250 ppm CO led to an increase in each of the maternal uterine blood flow, vascularity of the placenta and vessel diameter, with a shift towards angiogenesis in the placenta tissue proteins Exposure of human placental villous explants to 250ppm CO led to a decreased production and release of the soluble vascular endothelial growth factor (VEGF) receptor -1 (sFlt-1). This molecule is increased in maternal plasma and placenta tissue of women with PE and it binds with molecules of angiogenesis, limiting their ability to interact with the endothelium. Using an AdsFlt-1 PE-like mouse model, the exposure of mice to 250ppm chronic CO prevented the hypertension, proteinuria and glomerular alterations, supporting the use of CO as a future therapeutic for women with PE. We completed a pilot study to evaluate the exposure of healthy volunteers to two, one hour inhalations of 250ppm CO. We determined the half-life of CO and we provide baseline kinetics data for males and females following CO inhalation. These data are important for future therapeutic studies in order to better establish proper dosing, concentration of CO and method of delivery. The results of this thesis contribute to the understanding of the pathophysiology of PE and provide evidence to support the use of CO as a therapeutic for this disorder. / Thesis (Ph.D, Anatomy & Cell Biology) -- Queen's University, 2014-05-01 14:38:42.584

Thesis (Ph. D.)--University of Alabama at Birmingham, 2007. / Title from first page of PDF file (viewed Feb. 7, 2008). Includes bibliographical references (p. 50-57).

Thesis (Ph. D.)--Ohio State University, 2005. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2008 Aug 15.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Objective: To evaluate the protective effect of the heme-oxygenase 1 (HO-1)/biliverdin/CO pathway in models of gastropathy in mice, evaluating the role of the soluble guanylate cyclase (GCs) and of the constitutive NOS in this event. Methods: Protocol 1: Mice were pre-treated with hemin (HO-1 inducer; 1,3,10 mg/Kg, i.p.), biliverdin (HO-1 product; 1,3 or 10 mg/Kg., i.p.), DMDC (CO donor; 2.5, 7.5, 12.5 or 10 Âmol/Kg, i.p.) or ZnPP IX (HO-1 antagonist; 0,3, 1 or 3 mg/kg. i.p.), one hour before, gastric damage was induced by ethanol 50% (hemin, biliverdin, DMDC) or 25% (ZnPP IX). In another group, the animals were pre-treated with ODQ (12.5 mg/kg, v.o) or L-NAME (3 mg/Kg, v.o), thirty minutes before of the treatments cited previously. After 1h, the mice were sacrificed and the stomachs removed for evaluation of the gastric lesions (Image J). Protocol 2: Mice were pre-treated with hemin (3 mg/Kg, i.p.), biliverdin (3 mg/Kg., i.p.), DMDC (12,5 Âmol/Kg) or ZnPP IX (3,0 mg/kg), one hour before of the administration of INDO 30 mg/Kg (hemin, biliverdin, DMDC) or 10 mg/Kg (ZnPP IX). In another group, the animals were pre-treated with ODQ (12.5 mg/kg, v.o) or L-NAME (3 mg/Kg, v.o), thirty minutes before of the treatments cited previously. Three hours after, the mice were sacrificed and the stomachs removed for evaluation of the gastric lesions, utilizing a digital paquimetry. In all of the experimental groups, fragments of the gastric mucous were collected for determination of the concentration of MDA, GSH or bilirubin. Another samples of tissue was removed for microscopic analyzes and HO-1 expression by immunohistochemistry. The detection of the TNF-α, IL-1β, IL-10 and MPO activity were evaluated only in the INDO gastropathy. Results: Ethanol increased the expression of HO-1 and the levels of bilirrubin in the gastric tissue. Hemin, biliverdin and DMDC reduced gastric damage, MDA levels and GSH consume in ethanol 50%- induced gastropathy. The histological parameters, edema, hemorrhage and loses of epithelial cells, were diminished in the presence of hemin, biliverdin or DMDC. ZnPP IX amplified the ethanol-induced gastric lesion, increased MDA formation and decreased the GSH concentration in gastric mucosa. The histological parameters also were amplified after the handling with ZnPP IX. Bilirubin concentration was elevated during the protection induced by hemin and biliverdin, but not DMDC. INDO increased the HO-1 expression and the bilirrubin levels in the gastric mucosa. Hemin, biliverdin or DMDC reduced the gastric lesion, the MPO activity, and the MDA levels and increased the GSH concentration in the gastropathy INDO- induced. The histological parameters, edema, hemorrhage, loss of epithelial cells and the presence of inflammatory cells, were inhibited by hemin, biliverdin or DMDC. ZnPP IX amplified the effect of the INDO increasing the gastric lesion, the MPO activity, the MDA levels and the GSH consume. The histological parameters also were amplified after the handling with ZnPP IX. Bilirubin was shown elevated during the protection induced by hemin and biliverdin, but not DMDC. Hemin, biliverdin and DMDC diminished the TNF-α and IL-1β concentrations and increased the IL-10. ODQ and L-NAME completely abolished the DMDC protective gastric effect, but not biliverdin in the gastropathy ethanol or INDO- induced. Conclusion: HO-1/biliverdin/CO pathway plays a protective effect against ethanol or INDO-induced gastric damage. In the gastropathy by ethanol, the protection is dependent of the anti-oxidant action by bilirubin and CO. However, in the model of INDO gastropathy, we observe an anti-oxidant and anti-inflammatory action. The mechanism of gastro protective action of the CO, but not of the biliverdin, is dependent of the CO/ NOS/ GMPc pathway. / Objetivo: Avaliar o efeito protetor da via hemeoxigenase 1 (HO-1)/ biliverdina/ CO em modelos de gastropatia em camundongos e o papel da guanilato ciclase solÃvel (GCs) e da NOS constitutiva neste evento. MÃtodos: Protocolo 1: Camundongos foram prÃ-tratados hemina (indutor da HO-1; 1,3 ou 10mg/Kg, i.p.), biliverdina (produto da HO-1; 1,3 ou 10mg/Kg, i.p.), DMDC (doador de CO; 2,5, 7,5, 12,5 ou 25 μmol/Kg, i.p.) ou ZnPP I(inibidor da HO-1; 0,3, 1,0 ou 3,0 mg/kg. i.p.) uma hora antes da administraÃÃo por gavagem de etanol 50% (hemina, biliverdina, DMDC) ou 25% (ZnPP IX). Em outro grupo, os animais foram prÃ-tratados com ODQ (12,5 mg/kg, v.o) ou L-NAME (3 mg/Kg, v.o), trinta minutos antes dos tratamentos citados anteriormente. Depois de 1h, os camundongos foram sacrificados e os estÃmagos removidos para avaliaÃÃo das lesÃes gÃstricas (Image J). Protocolo 2: Camundongos foram prÃ-tratados hemina (3,0 mg/kg), biliverdina (3,0 mg/kg), DMDC (12,5 μmol/Kg) ou ZnPPIX (3,0 mg/Kg) uma hora antes da administraÃÃo de INDO 30 mg/Kg (hemina, biliverdina, DMDC) ou 10 mg/Kg (ZnPP IX). Em outro grupo os animais foram prÃ-tratados com ODQ (12,5 mg/kg, v.o) ou L-NAME (3 mg/Kg, v.o), trinta minutos antes dos tratamentos citados anteriormente. TrÃs horas depois, os camundongos foram sacrificados e os estÃmagos removidos para avaliaÃÃo das lesÃes gÃstrica, utilizando um paquÃmetro digital. Em todos os grupos experimentais, fragmentos da mucosa gÃstrica foram coletados para determinaÃÃo da concentraÃÃo de MDA, GSH e bilirrubina. Outra amostra de tecido foi retirada para analise microscÃpica e imunohistoquÃmica. A detecÃÃo das citocinas TNF-α, IL-1β e IL-10, bem como a atividade de MPO foram avaliados somente na gastropatia por INDO. Resultados: O etanol aumentou a expressÃo de enzima HO-1 e dos nÃveis de bilirrubina no tecido gÃstrico. Hemina, biliverdina ou DMDC reduziram a lesÃo gÃstrica, os nÃveis de MDA e o consumo de GSH induzido por etanol 50%. Os parÃmetros histolÃgicos, edema, hemorragia e perda de cÃlulas epiteliais, foram diminuÃdos na presenÃa de hemina, biliverdina ou DMDC. ZnPP IX amplificou o efeito do etanol 25%, aumentando a lesÃo gÃstrica, os nÃveis de MDA e o consumo de GSH. Os parÃmetros histolÃgicos tambÃm foram amplificados apÃs o tratamento com ZnPP IX. A concentraÃÃo de bilirrubina se mostrou elevada apenas na gastroproteÃÃo induzida por hemina e biliverdina, mas nÃo pelo DMDC. INDO aumentou a expressÃo da HO-1 e os nÃveis de bilirrubina na mucosa gÃstrica. Hemina, biliverdina ou DMDC reduziram a lesÃo gÃstrica, a atividade de MPO, os nÃveis de MDA e aumentaram a concentraÃÃo de GSH na gastropatia por INDO. Os parÃmetros histolÃgicos, edema, hemorragia, perda de cÃlulas epiteliais e a presenÃa de cÃlulas inflamatÃrias, foram inibidas pela hemina, biliverdina ou DMDC. ZnPP IX amplificou o efeito da INDO aumentando a lesÃo gÃstrica, a atividade de MPO, os nÃveis de MDA e o consumo de GSH. Os parÃmetros histolÃgicos tambÃm foram amplificados apÃs o tratamento com ZnPP IX. Bilirrubina se mostrou elevada apenas na gastroproteÃÃo induzida por hemina e biliverdina, mas nÃo pelo DMDC. Hemina, biliverdina e DMDC diminuÃram as concentraÃÃes de TNF-α e IL-1β e aumentaram a IL-10. ODQ e L-NAME reverteram o efeito protetor do DMDC, mas nÃo da biliverdina, na gastropatia induzida por etanol ou INDO. ConclusÃo: A via HO-1/biliverdina/CO participa do processo de defesa da mucosa gÃstrica contra lesÃes induzidas por etanol ou INDO. Na gastropatia por etanol, a proteÃÃo à dependente da aÃÃo antioxidante da bilirrubina e CO. Entretanto, no modelo de gastropatia por INDO, observamos uma aÃÃo antioxidante e antiinflamatÃria. Evidenciamos ainda que o mecanismo de aÃÃo gastroprotetor do CO, mas nÃo da biliverdina à dependente da via CO/GMPc/NOS.

Immunotherapy has revolutionized the treatment of certain cancers by facilitating the antitumor immune response and represents today one of the mainstays of cancer therapy. However, only a subset of patients responds to immunotherapy, which can also lead to serious complications. The tumor microenvironment is composed of multiple and complex cellular and molecular interactions providing to cancer cells not only a supportive framework but promoting also many steps of immunosuppression and tumor progression. To date, the mechanisms that drive the acquisition of these immunosuppressive features are still poorly defined. Tumor-associated macrophages can be highly represented in the tumor microenvironment where they are shaped and become key players in the innate and adaptive immune escape of the tumor cells.Heme oxygenase-1 is the rate-limiting enzyme that catabolizes heme into three major biologically active byproducts which display cytoprotective, antioxidant and immunomodulatory effects. We hypothesized that tumor-associated macrophages might suppress anti-tumor T-cell response through heme oxygenase-1 induction in the tumor microenvironment and macrophage polarization. We showed that heme oxygenase-1 is highly expressed in tumor-associated macrophages. By using a subcutaneous EG7-OVA lymphoma model on genetically engineered mice with a conditional deletion of heme oxygenase-1 in macrophages, our data show that myeloid-restricted heme oxygenase-1 deficiency improves the effect of a therapeutic antitumor immunization by enhancing tumor-infiltrating antitumor CD8+ T-cell proliferation and cytotoxicity and represses tumor growth. Our data suggest a major role of myeloid heme oxygenase-1 in the differentiation and the phenotypic, functional, transcriptional and epigenetic reprograming of tumor-associated macrophages. Myeloid HO-1 inhibition might be considered as a new myeloid HO-1-mediated immune checkpoint blockade. Targeting myeloid compartment could reprogram the tumor microenvironment and synergize with other cancer therapies. / Doctorat en Sciences médicales (Médecine) / info:eu-repo/semantics/nonPublished

Yes / Induction of the antioxidant enzyme heme oxygenase-1 (HO-1) affords cellular protection and suppresses proliferation of vascular smooth muscle cells (VSMCs) associated with a variety of pathological cardiovascular conditions including myocardial infarction and vascular injury. However, the underlying mechanisms are not fully understood. Over-expression of Cav3.2 T-type Ca2+ channels in HEK293 cells raised basal [Ca2+]i and increased proliferation as compared with non-transfected cells. Proliferation and [Ca2+]i levels were reduced to levels seen in non-transfected cells either by induction of HO-1 or exposure of cells to the HO-1 product, carbon monoxide (CO) (applied as the CO releasing molecule, CORM-3). In the aortic VSMC line A7r5, proliferation was also inhibited by induction of HO-1 or by exposure of cells to CO, and patch-clamp recordings indicated that CO inhibited T-type (as well as L-type) Ca2+ currents in these cells. Finally, in human saphenous vein smooth muscle cells, proliferation was reduced by T-type channel inhibition or by HO-1 induction or CO exposure. The effects of T-type channel blockade and HO-1 induction were non-additive. Collectively, these data indicate that HO-1 regulates proliferation via CO-mediated inhibition of T-type Ca2+ channels. This signalling pathway provides a novel means by which proliferation of VSMCs (and other cells) may be regulated therapeutically. / This work was supported by the British Heart Foundation.

Le système de l’hème oxygenase-1 (HO-1) constitue un système essentiel pour la vie grâce à ses activités anti-inflammatoire et anti-oxydante lui conférant une capacité de protection importante face à une multitude de pathologies. Les produits de dégradation de l’hème par l’hème oxygénase, essentiellement le CO, participent activement dans la protection procurée par le système de l’HO-1. Par conséquence, l’exploitation pharmacologique de ce système s’est montrée d’un intérêt particulier pour une application clinique potentielle. Dans ce contexte, le but de ce travail était la caractérisation de nouvelles molécules qui activent ce système de protection.Tout d’abord, CORM-401, une nouvelle molécule ayant le Mn comme métal et qui libère 3CO/mole de la molécule, a été caractérisée dans un contexte cardiovasculaire. CORM-401 a induit une relaxation significative et immédiate des anneaux aortiques pré-contractés avec de l’épinéphrine. En parallèle, CORM-401 s’est montré sensible au stress oxydant et la libération du CO par CORM-401 s’est accélérée significativement en présence des oxydants comme H2O2, ce qui s’est traduit par une relaxation plus poussée des anneaux aortiques. En plus, CORM-401 a induit la migration des cellules endothéliales EA.hy926, l’augmentation d’expression de différents facteurs angiogéniques ainsi que la phosphorylation de p38 MAPK et Akt. P38 MAPK et HO-1 se sont montrés impliqués dans la signalisation de l’angiogenèse induite par CORM-401.En parallèle, une nouvelle classe de molécule nommée HYCOs a été récemment synthétisée par notre groupe. Ces molécules sont formées par la liaison d’un inducteur de Nrf2/HO-1 à un CO-RM dans le but d’induire une réponse immédiate à la libération du CO et une réponse plus tardive à l’induction de Nrf2/HO-1. Les deux premières molécules de cette classe, HYCO-1 et HYCO-2, ont libéré du CO en solution d’une manière concentration-dépendante et HYCO-1 s’est montré plus efficace que HYCO-2 en termes d’induction de Nrf2 dans différentes lignées cellulaires. HYCO-1 a réduit significativement la production de nitrite par les cellules microgliales BV2 et les macrophages RAW 264.7 stimulées avec du LPS. Par conséquence, ces deux molécules ont prouvé la réussite du concept des HYCOs. / The heme oxygenase-1 (HO-1) pathway has emerged as a vital multifaceted system with important capacities of protection during pathological conditions characterized by oxidative stress and inflammation. The byproducts of this pathway, CO, BV and BR, were shown to contribute actively in mediating these protective effects. Thus the exploitation of the HO-1 pathway by different pharmacological tools seems to have interesting potential in clinical application. In this context, we aimed to characterize the biochemical and pharmacological activities of molecules targeting this pathway.First, a new Mn-based CO-RM named CORM-401 that releases 3CO/mole of compound with a slow kinetic was characterized in a cardiovascular context. CORM-401 induced immediate and significant relaxation in pre-contracted isolated aortic rings. Interestingly, CORM-401 has also shown to be susceptible to an oxidative environment since H2O2 potently enhanced the CO release by this compound and enhanced its vasodilatory effect. In addition, CORM-401 promoted the migration of EA.hy926 endothelial cells and induced the expression of different angiogenic factors along with the phosphorylation of P38 MAPK and Akt. HO-1 and p38 MAPK both participated in mediating the angiogenic effect of CORM-401.In parallel, a new class of hybrid molecules, named HYCOs, was recently synthesized by our group. These molecules were designed to possess an Nrf2 inducer moiety coordinated to a CO-RM in the purpose of inducing a prompt effect by the CO release and a delayed induction of Nrf2/HO-1 by the Nrf2 inducer moiety. HYCO-1 and HYCO-2, the first two compounds of this class, both released CO in solution in a concentration-dependent manner and HYCO-1 was more potent than HYCO-2 in inducing Nrf2 in different cell lines. HYCO-1 also significantly reduced nitrite production in BV2 microglia and RAW 264.7 macrophages stimulated with LPS. With these two molecules, the concept of designing HYCOs has proven its feasibility and its success.