PubMed Health⌕ Search

Biomedical subjects

Carolina Muscoli

Publications and source records attributed to Carolina Muscoli.

16 recordsLinked to original sources
PubMed2005

Reduction of antigen-induced respiratory abnormalities and airway inflammation in sensitized guinea pigs by a superoxide dismutase mimetic.

Reactive oxygen species have been implicated in the pathogenesis of asthma and, in atopic asthmatics, endogenous superoxide dismutase (SOD) enzyme levels are known to decrease. This suggests that replacing a failed endogenous SOD enzyme system with a mimetic of the endogenous enzyme would be beneficial and protective. In this study we demonstrate that removal of superoxide by the SOD mimetic (SODm) M40403 reduces the respiratory and histopathological lung abnormalities due to ovalbumin (OA) aerosol in a model of allergic asthma-like reaction in sensitized guinea pigs. Both respiratory abnormalities and bronchoconstriction in response to OA challenge are nearly absent in naïve animals, while they sharply became severe in sensitized animals. In addition, OA aerosol induced a reduction of MnSOD activity which was paralleled with bronchiolar lumen reduction, pulmonary air space hyperinflation, mast cell degranulation, eosinophil infiltration, bronchial epithelial cell apoptosis, increase in myeloperoxidase activity, malonyldialdehyde production and 8-hydroxy-2'-deoxyguanosine formation in the lung tissue, as well as elevation of PGD2 in the bronchoalveolar lavage fluid. Treatment with M40403 restored the levels of MnSOD activity and significantly reduced all the above parameters. In summary, our findings support the potential therapeutic use of SOD mimetics in asthma and anaphylactic reactions and account for a critical role for superoxide in acute allergic asthma-like reaction in actively sensitized guinea pig.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2005

Superoxide potentiates NF-kappaB activation and modulates endotoxin-induced cytokine production in alveolar macrophages.

Gram-negative bacterial infection predisposes to the development of shock and acute lung injury with multiple organ dysfunction in the critically ill. Although overexpression of proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-1beta, IL-6, IL-8, and other mediators is causally implicated in the pathogenesis of shock and lung injury, the underlying mechanisms following cellular exposure to gram-negative endotoxin remain unclear. De novo generation of reactive oxygen species (ROS) by monocytes/macrophages in particular has been proposed as a pivotal regulatory mechanism by which enhanced transactivation of redox-sensitive genes culminates in augmented cytokine expression within the lower respiratory tract. Here we sought to characterize the mechanism of action of a synthetic, nonpeptide, low-molecular-weight, Mn-containing superoxide dismutase mimetic (SODm), M40403, in modulating E. coli lipopolysaccharide serotype 0111:B4 (LPS)-induced cytokine production by cultured rat alveolar macrophages. Intracellular superoxide (O2) ion generation was measured using hydroethidine (HE) dye, and the dose-dependent effects of M40403 on TNF-alpha and IL-6 biosynthesis by ELISAs. Upstream redox-sensitive signaling events involving the pleiotropic transcription factor NF-kappaB were determined in nuclear extracts by electrophoretic mobility shift assays (EMSAs) and p65 subunit Western blot. The levels of the cytosolic inhibitory protein IkappaB-alpha were also assessed by Western analysis. We found that M40403 potently suppressed the production of superoxide, TNF-alpha, and IL-6 in LPS-stimulated alveolar macrophages, suggesting a key role for superoxide in endotoxin-induced cytokine production in the distal air spaces. In addition, M40403 decreased E. coli LPS-induced activation of NF-kappaB, and this effect was associated with modest suppression of cytoplasmic IkappaB-alpha degradation. Together, these results suggest that removal of superoxide by M40403 inhibits endotoxin-induced production of TNF-alpha and IL-6 in alveolar macrophages by a mechanism involving suppression of redox-sensitive NF-kappaB transactivation or signaling.

Animals↗
PubMed2005

Modulation of prostaglandin biosynthesis by nitric oxide and nitric oxide donors.

The biosynthesis and release of nitric oxide (NO) and prostaglandins (PGs) share a number of similarities. Two major forms of nitric-oxide synthase (NOS) and cyclooxygenase (COX) enzymes have been identified to date. Under normal circumstances, the constitutive isoforms of these enzymes (constitutive NOS and COX-1) are found in virtually all organs. Their presence accounts for the regulation of several important physiological effects (e.g. antiplatelet activity, vasodilation, and cytoprotection). On the other hand, in inflammatory setting, the inducible isoforms of these enzymes (inducible NOS and COX-2) are detected in a variety of cells, resulting in the production of large amounts of proinflammatory and cytotoxic NO and PGs. The release of NO and PGs by the inducible isoforms of NOS and COX has been associated with the pathological roles of these mediators in disease states as evidenced by the use of selective inhibitors. An important link between the NOS and COX pathways was made in 1993 by Salvemini and coworkers when they demonstrated that the enhanced release of PGs, which follows inflammatory mechanisms, was nearly entirely driven by NO. Such studies raised the possibility that COX enzymes represent important endogenous "receptor" targets for modulating the multifaceted roles of NO. Since then, numerous papers have been published extending the observation across various cellular systems and animal models of disease. Furthermore, other studies have highlighted the importance of such interaction in physiology as well as in the mechanism of action of drugs such as organic nitrates. More importantly, mechanistic studies of how NO switches on/off the PG/COX pathway have been undertaken and additional pathways through which NO modulates prostaglandin production unraveled. On the other hand, NO donors conjugated with COX inhibitors have recently found new interest in the understanding of NO/COX reciprocal interaction and potential clinical use. The purpose of this article is to cover the advances which have occurred over the years, and in particular, to summarize experimental data that outline how the discovery that NO modulates prostaglandin production has impacted and extended our understanding of these two systems in physiopathological events.

Animals↗
PubMed2004

The effect of inflammatory stimuli on NMDA-related activation of glutamine synthase in human cultured astroglial cells.

Removal of glutamate from the synaptic cleft by astroglial glutamine synthase (GS) is a crucial step in the regulation of glutamate turnover and metabolism, thus participating in endogenous neuroprotective processes occurring within brain tissues. Here we investigated on the effect of inflammatory cytokines on GS activity in astroglial cells undergoing NMDA receptors stimulation. Incubation of human cultured astroglial cells with NMDA (100 microM) enhanced GS expression, an effect driven by the generation of nitric oxide (NO) since l-NAME (500 microM), an inhibitor of NO synthase, reversed this effect. NMDA-related increase of GS activity and glutamine concentration was antagonised by previous incubation of astroglial cells with a mixture of LPS plus gammaIFN, an effect counteracted by dexamethasone, the latter effect being accompanied by inhibition of inducible NO synthase. These results show that LPS plus gammaIFN inhibit elevation of GS activity subsequent to NMDA receptor stimulation in astroglial cells via enhancement of inducible NO synthase, and this may represent the site of interaction between pro-inflammatory and excitotoxic stimuli in the brain.

Astrocytes↗
PubMed2004

The role of nitrinergic connections in central cardiovascular responses mediated by physostigmine infused into posterior hypothalamus.

In the last few decades, cholinergic connections located into posterior hypothalamus (PH) have been implicated in the central regulation of blood pressure (BP). Here we investigated the role of nitric oxide (NO) in the blood pressure response elicited by infusion of physostigmine into PH of normotensive rats. In freely moving rats, physostigmine (60-200 nM) produced a dose- and time-dependent elevation of BP which was antagonized by the antimuscarinic drug scopolamine (60 nM) and by L-NAME (100 microM), an inhibitor of NO synthase, both infused into the same site. In contrast, L-arginine (L-Arg; 100 microM), the precursor of NO, and glyceryltrinitrate (GTN; 140 nM), an NO donor, infused into the PH did not affect physostigmine-related pressor response. In rats pre-treated with Escherichia coli lipopolisaccharide (LPS; 0.5 microg i.p. 24h beforehand), however, scopolamine, L-Arg and GTN produced a decrease of BP, an effect antagonized by L-NAME. This suggests that NO only slightly modulates physostigmine-related pressor response elicited into PH of LPS-untreated rats. In contrast, the release of large amounts of NO generated by pre-treating rats with LPS, down-regulates cholinergic connections located at the PH, thus contributing in the central dysregulation of BP which can be found when high circulating endotoxin levels may occur.

Animals↗
PubMed2004

The protective effect of superoxide dismutase mimetic M40401 on balloon injury-related neointima formation: role of the lectin-like oxidized low-density lipoprotein receptor-1.

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), the principal receptor for oxidized low-density lipoprotein (ox-LDL) in vascular endothelial cells (ECs), has recently been suggested to exert a pivotal role in atherogenesis, possibly by mediating ox-LDL-evoked endothelial dysfunction. On the other hand, LOX-1 expression seems to strongly correlate with the oxidative stress occurring in the vascular wall of experimentally injured blood vessels. Here, we investigated LOX-1 expression and superoxide generation during neointima formation in a balloon injury rat carotid artery model. To test this, we used M40401 [a manganese(II) complex with a bis(cyclo-hexylpyridine-substituted) macrocyclic ligand], a synthetic superoxide dismutase mimetic that is a selective scavenger of superoxide. The injury was performed inserting the balloon catheter through the rat common carotid artery and after 14 days a histopathological analysis revealed a significant restenosis with smooth muscle cell proliferation and neointima formation that was associated with an enhanced expression of LOX-1, nitrotyrosine (the footprint of peroxynitrite) staining, and lipid peroxidation as assessed by malondialdehyde (MDA) formation. Pretreatment of rats with M40401 (0.5-10 mg/kg i.p. daily) reduced neointima formation, MDA accumulation, nitrotyrosine staining, and LOX-1 expression. Here, we show that removal of superoxide formation occurring in injured arteries reduces both neointima formation and LOX-1 expression and that this may represent a novel therapeutical approach in the treatment of vascular disorders in which proliferation of vascular smooth muscle cells and ox-LDL-related endothelial cell dysfunction occur.

Animals↗
PubMed2004

A newly identified role for superoxide in inflammatory pain.

Novel classes of pain-relieving molecules are needed to fill the void between nonsteroidal anti-inflammatory agents and narcotics. Our studies have identified superoxide as a novel mediator of hyperalgesia (clinically defined as an augmented sensitivity to painful stimuli) and have exposed potential pathways through which this radical modulates the hyperalgesic response. The role of superoxide in pain was elucidated using a superoxide dismutase mimetic, M40403 [a manganese(II) complex with a bis(cyclo-hexylpyridine-substituted) macrocyclic ligand]. Intraplantar injection of carrageenan in rats led to time-dependent development of peripheral inflammation [measured parameters of inflammation included paw edema, cytokine release in the paw exudates, nitrotyrosine formation (a marker of peroxynitrite formation and oxidative stress), and poly-ADP-ribose-polymerase activation (the nuclear enzyme activated by superoxide/peroxynitrite)] and hyperalgesia. M40403 blocked all measured parameters of inflammation and hyperalgesia. Furthermore, when given therapeutically (2 h after the induction of hyperalgesia) either by intravenous or intrathecal administration, M40403 but not its inactive congener M40404 inhibited hyperalgesia with a rapid onset of action. Our results also show that, at the level of the spinal cord and time of peak hyperalgesia, endogenous manganese superoxide dismutase was nitrated and subsequently deactivated, losing its capacity to remove superoxide. The antihyperalgesic effects of M40403 were not reversed by naloxone excluding the potential involvement of an opiate pathway. Collectively, these studies have unraveled a critical role for superoxide in the nociceptive signaling cascade both peripherally and centrally. The discovery of this pathway opens a new therapeutic strategy for the development of novel nonnarcotic antihyperalgesic agents.

Animals↗
PubMed2004

Superoxide-mediated nitration of spinal manganese superoxide dismutase: a novel pathway in N-methyl-D-aspartate-mediated hyperalgesia.

N-methyl-D-aspartate (NMDA) receptors serve prominent roles in vast physio-pathological conditions including hyperalgesia (defined as augmented pain intensity in response to painful stimuli) associated with central sensitization. Using M40403 a synthetic low molecular weight superoxide dismutase mimetic that removes superoxide we show for the first time that this radical plays a key role in NMDA-mediated hyperalgesia. Intrathecal administration of NMDA in rats led to a time-dependent development of thermal hyperalgesia. Removal of superoxide with M40403 abolished NMDA-mediated hyperalgesia, while its inactive congener had no effect. Thus NMDA-mediated hyperalgesic response to heat is mediated through spinal release of superoxide. At time of near-to-maximal hyperalgesia, we observed that spinal endogenous manganese superoxide dismutase (MnSOD), the enzyme that normally keeps superoxide under well-controlled condition was nitrated, as shown by immunoprecipitation. Subsequently and as determined by biochemical analysis, nitration of MnSOD led to its deactivation as shown by the loss of the enzyme's ability to dismute and hence remove superoxide. M40403 by preventing MnSOD nitration restored its activity and inhibited the hyperalgesic response to intrathecal NMDA. Thus, superoxide-mediated nitration and deactivation of spinal MnSOD is a novel pathway of NMDA-mediated spinal hyperalgesia and hence central sensitization since it helps to maintain high levels of superoxide that in turn maintains nociceptive signaling. The broader implication of our findings is that superoxide may contribute to various forms of pain events that are driven by NMDA-receptor activation.

Animals↗
PubMed2003

The protective effect of M40401, a superoxide dismutase mimetic, on post-ischemic brain damage in Mongolian gerbils.

BACKGROUND: Overproduction of free radical species has been shown to occur in brain tissues after ischemia-reperfusion injury. However, most of free radical scavengers known to antagonize oxidative damage (e.g. superoxide dismutase, catalase), are unable to protect against ischemia-reperfusion brain injury when given in vivo, an effect mainly due to their difficulty to gain access to brain tissues. Here we studied the effect of a low molecular weight superoxide dismutase mimetic (M40401) in brain damage subsequent to ischemia-reperfusion injury in Mongolian gerbils. RESULTS: In animals undergoing ischemia-reperfusion injury, neuropathological and ultrastructural changes were monitored for 1-7 days either in the presence or in the absence of M40401 after bilateral common carotid artery occlusion (BCCO). Administration of M40401 (1-40 mg/kg, given i.p. 1 h after BCCO) protected against post-ischemic, ultrastructural and neuropathological changes occurring within the hippocampal CA1 area. The protective effect of M40401 was associated with a significant reduction of the levels of malondialdehyde (MDA; a marker of lipid peroxidation) in ischemic brain tissues after ischemia-reperfusion. CONCLUSION: Taken together, these results demonstrate that M40401 provides protective effects when given early after the induction of ischemia-reperfusion of brain tissues and suggest the possible use of such compounds in the treatment of neurological dysfunction subsequent to cerebral flow disturbances.

Animals↗
PubMed2003

The role of oxidative stress in paraquat-induced neurotoxicity in rats: protection by non peptidyl superoxide dismutase mimetic.

Herbicides, including paraquat, may produce neurodegenerative effect when given both peripherally and into the brain though the pathophysiological mechanism is still unknown. Microinfusion of paraquat into the Substantia Nigra (50 microg) produced increased motor activity, jumping and circling opposite to the injection site, associated with ECoG desynchronization, high voltage epileptogenic spikes, and with neuropathological effects. These effects were accompanied by increase of malondialdehyde (MDA) levels in the Substantia Nigra, suggesting that paraquat was able to induce oxidative stress when injected directly into the rat brain. Pre-treatment of rats with M40401, a non peptidyl superoxide dismutase (SOD) mimetic given directly into the Substantia Nigra or i.p. prevented both behavioural, electrocorticogram and neuropathological effects and MDA elevation. Taken together, these results demonstrate that paraquat produces brain damage via abnormal formation of oxygen free radicals and that this effect may be counteracted by novel SOD mimetics.

Animals↗
PubMed2003

On the selectivity of superoxide dismutase mimetics and its importance in pharmacological studies.

The list of pathophysiological conditions associated with the overproduction of superoxide expands every day. Much of the knowledge compiled on the role of this radical in disease has been gathered using the native superoxide dismutase enzyme and, more recently, by the use of superoxide dismutase knockout models or transgenic models that overexpress the various isoforms of the enzyme. Although the native enzyme has shown promising anti-inflammatory properties in both preclinical and clinical studies, there were drawbacks and issues associated with its use as a therapeutic agent and pharmacological tool. Based on the concept that removal of superoxide modulates the course of inflammation, synthetic, low-molecular-weight mimetics of the superoxide dismutase enzymes that could overcome some of the limitations associated with the use of the native enzyme have been designed. In this review, we will discuss the advances made using various superoxide dismutase mimetics that led to the proposal that superoxide (and/or the product of its interaction with nitric oxide, peroxynitrite) is an important mediator of inflammation, and to the conclusion that superoxide dismutase mimetics can be utilized as therapeutic agents in diseases of various etiologies. The importance of the selectivity of such compounds in pharmacological studies will be discussed.

Animals↗
PubMed2002

Peroxynitrite decomposition catalyst prevents apoptotic cell death in a human astrocytoma cell line incubated with supernatants of HIV-infected macrophages.

BACKGROUND: Oxidative stress has shown to contribute in the mechanisms underlying apoptotic cell death occurring in AIDS-dementia complex. Here we investigated the role of peroxynitrite in apoptosis occurring in astroglial cells incubated with supernatants of HIV-infected human primary macrophages (M/M). RESULTS: Flow cytometric analysis (FACS) of human cultured astrocytes shortly incubated with HIV-1-infected M/M supernatants showed apoptotic cell death, an effect accompanied by pronounced staining for nitrotyrosine (footprint of peroxynitrite) and by abnormal formation of malondialdehyde (MDA). Pretreatment of astrocytes with the peroxynitrite decomposition catalyst FeTMPS antagonized HIV-related astrocytic apoptosis, MDA formation and nitrotyrosine staining. CONCLUSIONS: Taken together, our results suggest that inhibition of peroxynitrite leads to protection against peroxidative stress accompanying HIV-related apoptosis of astrocytes. Overall results support the role of peroxynitrite in HIV-related programmed death of astrocytes and suggest the use of peroxynitrite decomposition catalyst to counteract HIV-1-related neurological disorders.

Apoptosis↗
PubMed2002

Ethanol-induced injury in rat primary cortical astrocytes involves oxidative stress: effect of idebenone.

Ethanol-induced neurological disorders have recently been characterised. Indeed, evidence has been collected indicating that chronic ethanol consumption leads to direct or indirect changes in the viability of central nervous system cells. Here we investigated the role of free radical overproduction in primary cortical rat astroglial cells undergoing chronic treatment with ethanol (100 microM). In particular, exposure of astroglial cell cultures to ethanol for 12 consecutive days produced an increased release of lactic dehydrogenase, a decrease on glutamine synthase activity being both effects accompanied by decrease in astroglial viability as detected by MTT (Thiazolyl Blue) test. These effects were accompanied by an increased formation of malondialdehyde (a marker of lipid peroxidation) and by abnormal formation of heat shock protein, being both effects antagonised by liposomally entrapped idebenone, a non-peptidyl free radical scavenger. Taken together, these results suggest that ethanol-induced injury on astroglial cells are mediated by abnormal formation of free radical species and this may represent a useful approach in the treatment of ethanol-related brain disorders.

Animals↗
PubMed2002

Dexamethasone inhibits the inducible bioconversion of glyceryl trinitrate to nitric oxide.

The aim of this study was to assess the effects of dexamethasone (DEX) on the inducible bioconversion of glyceryl trinitrate (GTN) into nitric oxide in cultured smooth muscle cells, endothelial cells, and the J774 macrophage cell line as well as in vivo and ex vivo in rats either untreated or pretreated with Escherichia coli lipopolysaccharide. In vitro, an increased bioconversion of GTN to nitrite and an elevation of cyclosine guanosine 3,5;-monophosphate (cGMP) levels occurred after treatment with lipopolysaccharide (LPS) (0.5 microg/ml, 18 h). This effect was ablated by co-incubation with DEX (10 microM, 18 h). Rats treated with an intraperitoneal (IP) injection of LPS (4 mg/kg) 18 h beforehand showed enhanced hypotensive responses to GTN (1 mg/kg, intravenously [IV]) and this was prevented when DEX (4 mg/kg, IP) was given together with LPS. Progesterone (50 mg/kg, IP) had no effect on GTN-induced hypotensive response. Conversely, exposure of rat aortic strips obtained from animals pretreated with LPS produced an enhanced vasorelaxant response in LPS-treated rats. Also, this effect was inhibited by pretreatment with DEX. Thus, the induction of the pathway leading to the formation of nitric oxide from GTN is blocked by DEX both in vitro and in vivo, and this may represent a useful tool in the assessment of the enhanced bioconversion of organic nitrates into nitric oxide occurring via inflammatory mechanisms.

Animals↗
PubMed2002

The contribution of oxidative stress in apoptosis of human-cultured astroglial cells induced by supernatants of HIV-1-infected macrophages.

Apoptosis of neurons and astrocytes has been found in patients undergoing AIDS dementia complex. We demonstrated that supernatants from human primary macrophages (M/M) infected by HIV-1 lead human astroglial cells to oxidative stress, as shown by elevated levels of malondialdehyde, and then to apoptosis. Electron microscopy of astrocytes shortly incubated with HIV-1-infected M/M supernatants showed apoptotic blebbing, cytoplasmic loss, and chromatin condensation. Apoptosis was antagonized by pretreating astrocytes with the nonpeptidic superoxide dismutase (SOD) mimetic M40401 but not with anti-HIV-1 compounds, thus showing that apoptosis of astrocytes driven by HIV-1-infected M/M supernatants is mainly mediated by abnormal production of superoxide anions without relationship to HIV-1 replication in such cells. Overall results support the role of oxidative stress mediated by HIV-1-infected M/M as one of the leading causes of neurodegeneration in patients with HIV-1 and suggest the use of nonpeptidic SOD mimetics to counteract HIV-1-related neurological disorders.

Apoptosis↗