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Biomedical subjects

R Motterlini

Publications and source records attributed to R Motterlini.

At least 19 recordsLinked to original sources
PubMed2006

Positive inotropic effects of carbon monoxide-releasing molecules (CO-RMs) in the isolated perfused rat heart.

BACKGROUND AND PURPOSE: Carbon monoxide (CO) generated by the enzyme haeme oxygenase-1 (HO-1) during the breakdown of haeme is known to mediate a number of biological effects. Here, we investigated whether CO liberated from two water soluble carbon monoxide-releasing molecules (CO-RMs) exerts inotropic effects on the myocardium. EXPERIMENTAL APPROACH: Rat isolated hearts perfused either at constant flow or constant pressure were used to test the effect of CO-RMs. KEY RESULTS: CORM-3, a fast CO releaser, produced a direct positive inotropic effect when cumulative doses (3, 10 and 30 microg min(-1)) or a single dose (5 microM) were infused at either constant coronary pressure (CCP) or constant coronary flow (CCF). The inotropic effect mediated by CORM-3 was abolished by blockade of soluble guanylate cyclase or Na(+)/H(+) exchanger, but not by inhibitors of L-type Ca(2+) channels and protein kinase C. CORM-3 also caused a slight reduction in heart rate but did not alter coronary flow. In contrast, the slow CO releaser CORM-A1 produced significant coronary vasodilatation when given at the highest concentration (30 mug min(-1)) but exerted no effect on myocardial contractility or heart rate. CONCLUSION AND IMPLICATIONS: A rapid CO release from CORM-3 exerts a direct positive inotropic effect on rat isolated perfused hearts, whereas CO slowly released by CORM-A1 had no effect on myocardial contractility but caused significant coronary vasodilatation. Both cGMP and Na(+)/H(+) exchange appear to be involved in this effect but further work is needed to determine the relative contribution of each pathway in CO-mediated inotropic effect.

Alkaloids↗
PubMed2006

Role of carbon monoxide and biliverdin in renal ischemia/reperfusion injury.

Heme oxygenase (HO) isoforms catalyze the conversion of heme to carbon monoxide (CO) and biliverdin/bilirubin with a concurrent release of iron. There is strong evidence that HO activity and products play a major role in renoprotection, however the exact molecular mechanisms underlying the beneficial effects exerted by this pathway are not fully understood. This review is aimed at illustrating the possible mechanism/s by which HO is renoprotective in the context of ischemia/reperfusion. We will first analyze the effects of exogenous administration of bilirubin/biliverdin and CO and then describe their biological activities once generated endogenously following stimulation of the HO pathway by either pharmacological means or gene targeting-mediated approaches.

Animals↗
PubMed2006

Treatment with CO-RMs during cold storage improves renal function at reperfusion.

Low concentrations of carbon monoxide (CO) can protect tissues against ischemia-reperfusion (I-R) injury. We have recently identified a novel class of compounds, CO-releasing molecules (CO-RMs), which exert important pharmacological activities by carrying and delivering CO to biological systems. Here, we examined the possible beneficial effects of CO liberated from CO-RMs on the damage inflicted by cold storage and I-R in isolated perfused kidneys. Hemodynamic and biochemical parameters as well as mitochondrial respiration were measured in isolated perfused rabbit kidneys that were previously flushed with CO-RMs and stored at 4 degrees C for 24 h. Two water-soluble CO-RMs were tested: (1) sodium boranocarbonate (CORM-A1), a boron-containing carbonate that releases CO at a slow rate, and (2) tricarbonylchloro(glycinato)ruthenium(II) (CORM-3), a transition metal carbonyl that liberates CO very rapidly in solution. Kidneys flushed with Celsior solution supplemented with CO-RMs (50 microM) and stored at 4 degrees C for 24 h displayed at reperfusion a significantly higher perfusion flow rate (PFR), glomerular filtration rate, and sodium and glucose reabsorption rates compared to control kidneys flushed with Celsior solution alone. Addition of 1H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one (ODQ), a guanylate cyclase inhibitor, prevented the increase in PFR mediated by CO-RMs. The respiratory control index from kidney mitochondria treated with CO-RMs was also markedly increased. Notably, renal protection was lost when kidneys were flushed with Celsior containing an inactive compound (iCO-RM), which had been deliberately depleted of CO. CO-RMs are effective therapeutic agents that deliver CO during kidney cold preservation and can be used to ameliorate vascular activity, energy metabolism and renal function at reperfusion.

Animals↗
PubMed2005

Carbon monoxide reduces the expression and activity of matrix metalloproteinases 1 and 2 in alveolar epithelial cells.

Matrix metalloproteinases (MMPs), particularly MMP-1 and MMP-2, are involved in the pathophysiology of emphysema. MMPs contain zinc in the catalytic site and its expression is regulated transcriptionally via mitogen activated protein kinases (MAPKs). Carbon monoxide (CO), one of the end products of heme oxygenase activity, has anti-inflammatory properties, which are mediated, at least in part, by activation of p38 MAPK. Furthermore, CO has the unique ability to bind to metal centers in proteins and can affect their specific activity. Therefore, we hypothesized that CO could inhibit MMPs expression and/or activity. Here we show that a recently identified carbon monoxide-releasing molecule, [Ru(CO)3Cl2]2 (or CORM-2) inhibits MMP-1 and MMP-2 mRNA expression in the human lung epithelial cell line A549. The MMPs mRNA expression was unaffected by the p38 MAPK inhibitor SB203580, but in the case of MMP-1 was reversed by the antioxidant N-acetylcysteine. In addition, CORM-2 inhibited both MMP-1 and MMP-2 activities. Interestingly, no effect was observed with (Ru(DMSO)4Cl2), a negative control that does not contain CO groups. To the best of our knowledge this is the first evidence on the effect of CO on MMPs expression and activity. This effect could have important implications in the pathophysiology of emphysema and other diseases involving proteases/antiproteases imbalance.

Carbon Monoxide↗
PubMed2005

Reviewing the use of carbon monoxide-releasing molecules (CO-RMs) in biology: implications in endotoxin-mediated vascular dysfunction.

The inducible stress protein heme oxygenase-1 (HO-1) has been linked to tissue and organ protection against the deleterious actions of many pathological conditions, including endotoxin challenge. Similar protection can be achieved by the main products of heme oxygenase activity, namely bilirubin and carbon monoxide (CO). Since the identification of novel chemical compounds that liberate CO in biological systems (CO-releasing molecules or CO-RMs), our group and others have had access to a convenient and simple pharmacological tool that enables to study the role of CO in physiological functions. This article will review the scientific literature published to date on CO-RMs, with emphasis on the in vitro, ex vivo and in vivo experimental models employed to determine the contribution of CO to cellular mechanisms. In addition, we will report on the effect of heme oxygenase-related substances, such as bilirubin, CORM-3 and hemin, in a model of endotoxin-induced hypotension. Among the three different approaches examined, CORM-3 proved the most effective agent in reducing the fall in blood pressure caused by endotoxin. Furthermore, heme oxygenase-related substances affected the endotoxin-stimulated induction and distribution of hepatic HO-1 and inducible nitric oxide synthase (iNOS). Thus, it emerges that CO-RMs could exert important biological actions in the context of endotoxic-mediated dysfunction.

Animals↗
PubMed2005

Carbon monoxide-releasing molecules (CO-RMs) modulate respiration in isolated mitochondria.

Emerging evidence reveals that heme oxygenase-1 (HO-1) and its product carbon monoxide (CO) can exert diverse biological and cytoprotective effects. Our group has recently identified a new class of compounds (CO-releasing molecules or CO-RMs) that can carry and deliver CO to biological systems and can be used to examine the physiological properties of CO. Here, we evaluated the influence of endogenously-generated CO (via HO-1 induction by hemin) and CO liberated from exogenously supplied CO-RMs on mitochondrial function. Renal mitochondria were isolated either from rats with increased HO-1 or from untreated animals, the latter being exposed to different concentrations of CO-RMs (10-100 microM). We found that mitochondrial oxygen uptake was significantly reduced in kidneys after HO-1 induction and, in a similar fashion, CO-RMs inhibited mitochondrial function in a concentration-dependent manner. Specifically, a marked depression of state 3 was observed resulting in a significant decrease in respiratory control index (RCI) values. When mitochondria were incubated with the inactive forms of CO-RMs, which are devoid of CO, the respiratory parameters remained unchanged. In summary, the results indicate that HO-1 induction and enhanced CO decrease renal oxygen consumption and alter mitochondrial function suggesting that CO could be a physiological regulator of mitochondrial oxidative phosphorylation.

Animals↗
PubMed2002

Caffeic acid phenethyl ester and curcumin: a novel class of heme oxygenase-1 inducers.

Heme oxygenase-1 (HO-1) is a redox-sensitive inducible protein that provides efficient cytoprotection against oxidative stress. Curcumin, a polyphenolic natural compound that possesses anti-tumor and anti-inflammatory properties, has been reported recently to induce potently HO-1 expression in vascular endothelial cells (Free Rad Biol Med 28:1303-1312, 2000). Here, we extend our previous findings by showing that caffeic acid phenethyl ester (CAPE), another plant-derived phenolic agent, markedly increases heme oxygenase activity and HO-1 protein in astrocytes. The effect seems to be related to the peculiar chemical structures of curcumin and CAPE, because analogous antioxidants containing only portions of these two molecules were totally ineffective. At a final concentration of 30 microM, both curcumin and CAPE maximally up-regulated heme oxygenase activity while promoting marked cytotoxicity at higher concentrations (50-100 microM). Similar results were obtained with Curcumin-95, a mixture of curcuminoids commonly used as a dietary supplement. Incubation of astrocytes with curcumin or CAPE at concentrations that promoted maximal heme oxygenase activity resulted in an early increase in reduced glutathione followed by a significant elevation in oxidized glutathione contents. A curcumin-mediated increase in heme oxygenase activity was not affected by the glutathione precursor and thiol donor N-acetyl-L-cysteine. These data suggest that regulation of HO-1 expression by polyphenolic compounds is evoked by a distinctive mechanism which is not necessarily linked to changes in glutathione but might depend on redox signals sustained by specific and targeted sulfydryl groups. This study identifies a novel class of natural substances that could be used for therapeutic purposes as potent inducers of HO-1 in the protection of tissues against inflammatory and neurodegenerative conditions.

Acetylcysteine↗
PubMed2002

Interaction of heme with nitroxyl or nitric oxide amplifies heme oxygenase-1 induction: involvement of the transcription factor Nrf2.

Heme oxygenase-1 (HO-1) is a cytoprotective enzyme, the expression of which is highly sensitive to induction by pro-oxidant stimuli including the substrate heme and reactive oxygen species. Conceptually, the perception that HO-1 plays a key role in response to oxidative damage is paralleled by evidence showing high expression of HO-1 in a variety of cell systems challenged with nitric oxide (NO) or NO-derivatives, thus revealing a potential biological function for HO-1 against nitrosative stress. In this study, we report that exposure of cardiac cells to hemin (5-20 microM) in combination with compounds that liberate nitroxyl (HNO/NO-) or release NO significantly potentiates HO-1 mRNA and protein expression leading to a remarkable increase in heme oxygenase activity under both normoxic and hypoxic conditions. The amplification of the heme oxygenase pathway appears to involve a direct interaction between heme and the NO groups, as the ability of both NO(-)- and NO-releasing agents to induce HO-1 is totally lost by their pre-incubation for 1 hr in complete medium prior to cell treatment but is highly preserved by addition of hemin during the preincubation step. In addition, we show that the redox-sensitive transcription factor Nrf2 is highly expressed in the nuclear fraction of cells exposed to the NO- generator and that this effect is totally abolished by the presence of N-acetyl-L-cysteine. Interestingly, the expression of Nrf2 is gradually intensified by treating cells with a combination of the NO- releaser and increasing concentrations of hemin. Thus, a strict parallelism exists between the extent of HO-1 induction and expression of Nrf2 elicited by the heme-NO interaction. We propose that modification of the iron protoporphyrin centers by NO groups to modulate HO-1 expression might be regarded as a molecular switch to maximize heme oxygenase enzymatic activity and consequently mitigate the redox imbalance imposed by oxidative and nitrosative stress.

Acetylcysteine↗
PubMed2001

Homocysteine attenuates endothelial haem oxygenase-1 induction by nitric oxide (NO) and hypoxia.

The disrupted metabolism of homocysteine (Hcy) causes hyperhomocysteinemia, a condition associated with the impairment of nitric oxide (NO) bio-availability, tissue hypoxia and increased risk of vascular disease. Here, we examined how Hcy modulates the induction of the stress protein haem oxygenase-1 (HO-1) evoked by NO releasing agents and hypoxia in vascular endothelial cells. We found that Hcy (0.5 mM) markedly reduced the increase in haem oxygenase activity and HO-1 protein expression induced by sodium nitroprusside (SNP, 0.5 mM) but did not affect HO-1 activation mediated by S-nitroso-N-acetyl-penicillamine. Cells pre-treated with Hcy followed by addition of fresh medium containing SNP still exhibited an augmented haem oxygenase activity. Interestingly, high levels of Hcy were also able to abolish hypoxia-mediated HO-1 expression in a concentration-dependent manner. These novel findings indicate that hyperhomocysteinemia interferes with crucial signaling pathways required by cells to respond and adapt to stressful conditions.

Animals↗
PubMed2001

Role of heme oxygenase-1 in hypoxia-reoxygenation: requirement of substrate heme to promote cardioprotection.

Heme oxygenase-1 (HO-1) catalyzes the enzymatic degradation of heme to carbon monoxide, bilirubin, and iron. All three products possess biological functions; bilirubin, in particular, is a potent free radical scavenger of which its antioxidant property is enhanced at low oxygen tension. Here, we investigated the effect of severe hypoxia and reoxygenation on HO-1 expression in cardiomyocytes and determined whether HO-1 and its product, bilirubin, have a protective role against reoxygenation damage. Hypoxia caused a time-dependent increase in both HO-1 expression and heme oxygenase activity, which gradually declined during reoxygenation. Reoxygenation of hypoxic cardiomyocytes produced marked injury; however, incubation with hemin or bilirubin during hypoxia considerably reduced the damage at reoxygenation. The protective effect of hemin is attributable to increased availability of substrate for heme oxygenase activity, because hypoxic cardiomyocytes generated very little bilirubin when incubated with medium alone but produced substantial bile pigment in the presence of hemin. Interestingly, incubation with hemin also maintained high heme oxygenase activity levels during the reoxygenation period. Reactive oxygen species generation was enhanced after hypoxia, and hemin and bilirubin were capable once again to attenuate this effect. These results indicate that the HO-1-bilirubin pathway can effectively defend hypoxic cardiomyocytes against reoxygenation injury and highlight the issue of heme availability in the cytoprotective action afforded by HO-1.

Animals↗
PubMed2001

Protective role of heme oxygenases against endotoxin-induced diaphragmatic dysfunction in rats.

Reactive oxygen species are strongly implicated in diaphragmatic dysfunction during sepsis. We investigated whether the heme oxygenase (HO) pathway, which is a powerful protective cellular system, protects the diaphragm against oxidative stress and contractile failure during sepsis. A basal expression of both the inducible and constitutive HO protein isoforms (HO-1 and HO-2, respectively) was found in the diaphragm. Enhanced HO-1 expression in diaphragmatic myocytes was observed 24 h after Escherichia coli endotoxin (lipopolysaccharide, LPS) inoculation and remained elevated for at least 96 h. Enhanced HO-1 expression was also observed in the rectus abdominis and soleus muscles and in the left ventricular myocardium of endotoxemic animals. Diaphragmatic HO-2 expression was not modified by endotoxin. Diaphragmatic HO activity exhibited a biphasic time course characterized by a transient decrease during the first 12 h followed by a significant increase at 24 h, corresponding to HO-1 induction. Diaphragmatic force was significantly reduced 24 h after LPS, concomitantly with muscular oxidative stress. Administation of an inhibitor of heme oxygenase activity, zinc protoporphyrin IX (ZnPP-IX), further impaired muscular oxidative stress and contractile failure. By contrast, increased levels of HO-1 expression obtained by pretreatment of rats with hemin, a powerful inducer of HO-1, completely prevented LPS-mediated diaphragmatic oxidative stress and contractile failure. This protective effect was reversed by ZnPP-IX. These results show an important protective role for the HO pathway against sepsis-induced diaphragmatic dysfunction, which could be related to its antioxidant properties.

Animals↗
PubMed2000

Dynamics of haem oxygenase-1 expression and bilirubin production in cellular protection against oxidative stress.

The inducible isoform of haem oxygenase (HO-1) has been proposed as an effective system to counteract oxidant-induced cell injury. In several circumstances, this cytoprotective effect has been attributed to increased generation of the antioxidant bilirubin during haem degradation by HO-1. However, a direct implication for HO-1-derived bilirubin in protection against oxidative stress remains to be established. In the present study, we examined the dynamics of HO-1 expression and bilirubin production after stimulation of vascular smooth-muscle cells with hemin, a potent inducer of the HO-1 gene. We found that hemin-mediated increase in HO-1 protein expression and haem oxygenase activity is associated with augmented bilirubin levels. The majority of bilirubin production occurred early after exposure of cells to hemin. Hemin pre-treatment also resulted in high resistance to cell injury caused by an oxidant-generating system. Interestingly, this protective effect was manifest only when cells were actively producing bilirubin as a consequence of increased haem availability and utilization by HO-1. Tin protoporphyrin IX, an inhibitor of haem oxygenase activity, significantly reduced bilirubin generation and reversed cellular protection afforded by hemin treatment. Furthermore, addition of bilirubin to the culture medium markedly reduced the cytotoxicity produced by oxidants. Our findings provide direct evidence that bilirubin generated after up-regulation of the HO-1 pathway is cytoprotective against oxidative stress.

Animals↗
PubMed2000

Endothelial heme oxygenase-1 induction by hypoxia. Modulation by inducible nitric-oxide synthase and S-nitrosothiols.

The stress protein heme oxygenase-1 (HO-1) is induced in endothelial cells exposed to nitric oxide (NO)-releasing agents, and this process is finely modulated by thiols (Foresti, R., Clark, J. E., Green, C. J., and Motterlini R. (1997) J. Biol. Chem. 272, 18411-18417). Here, we report that up-regulation of HO-1 in aortic endothelial cells by severe hypoxic conditions (pO(2) </= 2 mm Hg) is preceded by increased inducible NO synthase and NO synthase activity. This effect is accompanied by oxidation of intracellular glutathione and formation of S-nitrosothiols. Incubation of cells with a selective inhibitor of inducible NO synthase (S-(2-aminoethyl)-isothiourea) or a NO scavenger ([2-(4-carboxyphenyl)-4,4,5, 5-tetramethylimidazoline-1-oxyl-3-oxide]) significantly attenuated the increase in heme oxygenase activity caused by reduced oxygen availability. A series of antioxidant agents did not prevent the elevation in heme oxygenase activity by hypoxia; however, the precursor of glutathione synthesis and thiol donor, N-acetylcysteine, completely abolished HO-1 induction. We also found that the hypoxia-mediated increase in endothelial heme oxygenase activity was potentiated by the presence of S-nitrosoglutathione. These results indicate that intracellular interaction of thiols with NO is an important determinant in the mechanism leading to HO-1 induction by reduced oxygen levels. We suggest that in addition to oxidative stress, HO-1 gene expression can be regulated by redox reactions involving NO and S-nitrosothiols (nitrosative stress), emphasizing a versatile role for the heme oxygenase pathway in the cellular adaptation to a variety of stressful conditions.

Animals↗
PubMed2000

Curcumin, an antioxidant and anti-inflammatory agent, induces heme oxygenase-1 and protects endothelial cells against oxidative stress.

Curcumin, a widely used spice and coloring agent in food, has been shown to possess potent antioxidant, antitumor promoting and anti-inflammatory properties in vitro and in vivo. The mechanism(s) of such pleiotropic action by this yellow pigment is unknown; whether induction of distinct antioxidant genes contributes to the beneficial activities mediated by curcumin remains to be investigated. In the present study we examined the effect of curcumin on endothelial heme oxygenase-1 (HO-1 or HSP32), an inducible stress protein that degrades heme to the vasoactive molecule carbon monoxide and the antioxidant biliverdin. Exposure of bovine aortic endothelial cells to curcumin (5-15 microM) resulted in both a concentration- and time-dependent increase in HO-1 mRNA, protein expression and heme oxygenase activity. Hypoxia (18 h) also caused a significant (P < 0.05) increase in heme oxygenase activity which was markedly potentiated by the presence of low concentrations of curcumin (5 microM). Interestingly, prolonged incubation (18 h) with curcumin in normoxic or hypoxic conditions resulted in enhanced cellular resistance to oxidative damage; this cytoprotective effect was considerably attenuated by tin protoporphyrin IX, an inhibitor of heme oxygenase activity. In contrast, exposure of cells to curcumin for a period of time insufficient to up-regulate HO-1 (1.5 h) did not prevent oxidant-mediated injury. These data indicate that curcumin is a potent inducer of HO-1 in vascular endothelial cells and that increased heme oxygenase activity is an important component in curcumin-mediated cytoprotection against oxidative stress.

Animals↗
PubMed2000

Heme oxygenase-1-derived bilirubin ameliorates postischemic myocardial dysfunction.

Bilirubin is a potent antioxidant generated intracellularly during the degradation of heme by the enzyme heme oxygenase. The purpose of this study was to determine the role of increased cardiac bilirubin in protection against postischemic myocardial dysfunction. Rat hearts were isolated and perfused according to the Langendorff technique to evaluate the recovery of myocardial function after 30 min of global ischemia and 60 min of reperfusion. We found that upregulation of the inducible isoform of heme oxygenase (HO-1) by treatment of animals with hemin 24 h before ischemia ameliorated myocardial function and reduced infarct size (tetrazolium staining) on reperfusion of isolated hearts. Tin protoporphyrin IX, an inhibitor of heme oxygenase activity, completely abolished the improved postischemic myocardial performance observed after hemin-mediated HO-1 induction. Likewise, cardiac tissue injury was exacerbated by treatment with tin protoporphyrin IX. Increased cardiac HO-1 expression and heme oxygenase activity were associated with enhanced tissue bilirubin content and an increased rate of bilirubin release into the perfusion buffer. Furthermore, exogenously administered bilirubin at concentrations as low as 100 nanomolar significantly restored myocardial function and minimized both infarct size and mitochondrial damage on reperfusion. Our data provide strong evidence for a primary role of HO-1-derived bilirubin in cardioprotection against reperfusion injury.

Animals↗
PubMed1999

Fibre type specificity of haem oxygenase-1 induction in rat skeletal muscle.

The expression of the inducible haem oxygenase (HO-1) gene was examined in different skeletal muscles. Rats were treated with haemin and a time course of HO-1 mRNA expression was determined in soleus and extensor digitorum longus (EDL) muscles. Fibre type composition and tissue myoglobin content were also measured. We found that HO-1 mRNA expression markedly increased in soleus (type I fibres) muscle but was only slightly affected in EDL (type II fibres). HO-1 expression directly correlated with both percentage of red fibres and tissue myoglobin. These data demonstrate that HO-1 gene expression follows a fibre type-specific pattern which might indicate an important role for this protein in the maintenance of skeletal muscle function.

Adenosine Triphosphatases↗