Search

Carbon monoxide (CO) is one of the cytoprotective byproducts of heme oxygenase (HO)-1 and exerts anti-inflammatory action in various models. However, the detailed mechanisms underlying CO-induced HO-1 expression in primary human cardiomyocytes remain largely unidentified. We used primary left ventricle myocytes as a model and applied CO releasing molecule (CORM)-2 to investigate the relationship of CO and HO-1 expression. We herein used Western blot, real-time PCR, promoter activity and EIA to investigate the role of HO-1 expression protecting against thrombin-mediated responses. We found that thrombin-induced COX-2 expression, PGE 2 release and cardiomyocyte hypertrophy markers (increase in ANF/BNP, α-actin expression and cell surface area) was attenuated by pretreatment with CORM-2 which was partially reversed by hemoglobin (Hb) or ZnPP (an inhibitor of HO-1 activity), suggesting that HO-1/CO system may be of clinical importance to ameliorate heart failure through inhibition of inflammatory responses. CORM-2-induced HO-1 protein expression, mRNA and promoter was attenuated by pretreatment with the inhibitors of Pyk2 (PF431396), PDGFR (AG1296), PI3K (LY294002), Akt (SH-5), p38 (SB202530), JNK1/2 (SP600125), FoxO1 (AS1842856) and Sp1 (mithramycin A). The involvement of these signaling components was further confirmed by transfection with respective siRNAs, consistent with those of pharmacological inhibitors. These results suggested that CORM-2-induced HO-1 expression is mediated through a Pyk2/PDGFR/PI3K/Akt/FoxO1/Sp1-dependent manner and exerts a cytoprotective effect in human cardiomyocytes. [ABSTRACT FROM AUTHOR]

The effect of CO on the expression of iNOS and COX-2 was investigated by using a CO-releasing molecule (CORM)-2 in LPS-activated RAW 264.7 cells in vitro. Interestingly, CORM-2 significantly inhibited iNOS (NO) but not COX-2 (PGE2) expression. PPAR-γ activators such as troglitazone, GW1929, and 15-deoxy-Δ12, 14- prostaglandin J2 showed preferential inhibitory effect on iNOS over COX-2 expression in LPS-activated macrophages. The same effect was shown in lung tissues (iNOS, COX-2) and serum (NO, PGE2) when administered of CORM-2 in LPS-induced septic mice, indicating that CO derived from CORM-2 differentially regulates iNOS and COX-2 through PPAR-γ activation under inflammation state. [ABSTRACT FROM AUTHOR]

Abstract: Carbon monoxide (CO) arising from heme degradation, catalyzed particularly by the stress-inducible heme oxygenase-1 (HO-1), has recently been demonstrated to provide cytoprotection against cell death in macrophages stimulated with bacterial lipopolysaccharide (LPS). In the present study, we determined the effects of CO on the production of reactive oxygen species (ROS) and nitric oxide (NO) by the LPS-stimulated RAW 264.7 macrophages. In addition, effect of CO-exposure on the production of superoxide (O2 −) in the phorbol myristate acetate (PMA)-stimulated PLB-985 neutrophils was determined. Production of ROS by the LPS-stimulated macrophages pretreated with 50μM [Ru(CO)3Cl2]2, a CO-releasing molecule (CORM-2), was abolished and the production of O2 − by the PMA-stimulated neutrophils pretreated with the CORM-2 was decreased markedly. The CORM-2 (50μM) was not cytotoxic to both the unstimulated and LPS-stimulated macrophages when determined by employing mitochondrial reductase function test (MTT assay). In macrophages pretreated with increasing doses of CORM-2, both the LPS-derived upregulations of iNOS (NO production) and HO-1 expression (CO production) were suppressed in a dose-dependent manner. Alternatively, when the macrophages were treated with LPS and CO-donor together, the LPS-derived increase in NO production was decreased. Conversely, when the control and LPS-stimulated macrophages were treated with zinc protoporphyrin IX (ZnPP) to inhibit the HO activity blocking endogenous production of CO (basal and enhanced), macrophages died extensively. Interestingly, production of NO in the LPS-stimulated macrophages increased significantly following the ZnPP treatment. Addition of CORM-2 to the LPS-treated cells that were being treated additionally with ZnPP did not prevent the cell death. However, endogenous overproduction of CO by super-induction of HO-1 (obtained by pretreatment of macrophages with either buthionine sulfoximine or hemin) decreased the LPS-derived iNOS expression without affecting cell survival. Combined, these results indicated that enhanced HO activity is essential for the survival of LPS-stimulated macrophages. Thus, upregulation of HO-1 and overproduction of CO may allow the survival of LPS-stimulated macrophages; first, by eliminating the free heme to prevent Fenton reaction, second, by limiting the availability of free heme required for induction of NO-producing heme enzyme (i.e., iNOS), third, by limiting additional production of O2 − and NO via CO-derived inhibition on the activities of heme enzymes like NADPH oxidase and iNOS, respectively. CO may allow the LPS-activated macrophages to return back to the normal quiet state insensitive to additional stimuli causing oxidative stress. [Copyright &y& Elsevier]

OBJECTIVES: Oxidative stress caused by reactive oxygen species (ROS) inhibiting the effects of the body's antioxidant system is the main pathology of many diseases. Heme oxygenase (HO) in the cellular antioxidant system is oxidative sensor protein induced by ROS formation or carbon monoxide (CO) production. CORM-2 (tricarbonyldichlororuthenyum-II), Co releasing molecule induces the expression of heme oxygenase-1 (HO-1). The aim of the study is to determine the effect of CORM-2 on hydrogen peroxide (H2O2) induced neuroblastoma cells (SH-SY5Y) through HO-1 induction. MATERIAL&METHODS: To determine the effective concentration of CORM-2, MTT analyze was performed. The cells were treated with 1 μM, 5 μM, 10 μM, 25 μM and 50 μM concentrations of CORM-2. At the end of the MTT analysis 20 μM and 50 μM concentrations were determined for Western Blot and Real-Time PCR experiments. The cells were pre-treated with the 20UM and 50 UM concentrations of CORM-2 for 3 hours, then they were induced with 300 μM H2O2 for 3 hours. The samples were prepared for Western Blot and Real-Time PCR experiments. RESULTS: CORM-2 molecule significantly affected cell viability in SHSY-5Y cells in the dose range of 10 μM- 50 μM. The expression of HO-1 (0.42 ± 0.02 and 0.82 ± 0.13 control and 20 μM respectively, n = 3) was increased in SH-SY5Y cells which are pretreated with the 20 μM and 50 μM CORM-2 concentrations as a result of Western Blot experiments. CONCLUSIONS: In the presence of oxidative stress, CORM-2 increased HO-1 expression. This may be significant in carcinogenesis and neurodegenerative disorders. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Heme oxygenase-1 (HO-1) is the rate limiting enzyme that catalyzes the conversion of heme into biliverdin, free iron, and carbon monoxide (CO). The first human case of HO-1 deficiency showed abnormalities in blood coagulation and the fibrinolytic system. Thus, HO-1 or HO-1 products, such as CO, might regulate coagulation and the fibrinolytic system. This study examined whether tricarbonyldichlororuthenium (II) dimer (CORM-2), which liberates CO, modulates the expression of tissue factor (TF) and plasminogen activator inhibitor type 1 (PAI-1) in human umbilical vein endothelial cells (HUVECs), and TF expression in peripheral blood mononuclear cells (PBMCs). Additionally, we examined the mechanism by which CO exerts its effects. Materials and Methods: HUVECs were pretreated with 50μM CORM-2 for 3hours, and stimulated with tumor necrosis factor-α (TNF-α, 10ng/ml) for an additional 0–5hours. PBMCs were pretreated with 50–100μM CORM-2 for 1hour followed by stimulating with lipopolysaccharid (LPS, 10ng/ml) for additional 0–9hours. The mRNA and protein levels were determined by RT-PCR and western blotting, respectively. Results: Pretreatment with CORM-2 significantly inhibited TNF-α-induced TF and PAI-1 up-regulation in HUVECs, and LPS-induced TF expression in PBMCs. CORM-2 inhibited TNF-α-induced activation of p38 MAPK, ERK1/2, JNK, and NF-κB signaling pathways in HUVECs. Conclusions: CORM-2 suppresses TNF-α-induced TF and PAI-1 up-regulation, and MAPKs and NF-κB signaling pathways activation by TNF-α in HUVECs. CORM-2 suppresses LPS-induced TF up-regulation in PBMCs. Therefore, we envision that the antithrombotic activity of CORM-2 might be used as a pharmaceutical agent for the treatment of various inflammatory conditions. [Copyright &y& Elsevier]