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Luigi Sironi

Publications and source records attributed to Luigi Sironi.

17 recordsLinked to original sources
PubMed2006

Gender differences in endothelial function and inflammatory markers along the occurrence of pathological events in stroke-prone rats.

Spontaneously hypertensive stroke-prone rats (SHRSP) feature an established model for human cerebrovascular disease. SHRSP, kept on a high-salt permissive diet (JPD), develop hypertension, renal and brain damage. In this report we compared the behavior of female and male SHRSP regarding the main aspects of their pathological condition. Brain abnormalities, detected by magnetic resonance imaging, developed spontaneously in males after 42+/-3 days, in females after 114+/-14 days from the start of JPD. Survival was >3-fold longer for females than for males. The development of brain damage was preceded, in both genders, by an inflammatory condition characterized by the accumulation in serum and urine of acute-phase proteins. The increase in thiostatin level was significantly lower and delayed in female in comparison to male SHRSP. During JPD female and male SHRSP developed massive proteinuria, its worsening being significantly slower in females. The alterations of vasculature-bound barriers in kidney and brain were connected with endothelial dysfunction and relative deficiency in nitric oxide (NO). In thoracic aortic rings, basal release of NO was significantly higher in female than in male SHRSP, both if receiving and if not receiving JPD. The gender differences in SHRSP thus appear to be connected to a more efficient control in females of inflammation and of endothelial dysfunction.

Acute-Phase Proteins↗
PubMed2006

The orphan receptor GPR17 identified as a new dual uracil nucleotides/cysteinyl-leukotrienes receptor.

Nucleotides and cysteinyl-leukotrienes (CysLTs) are unrelated signaling molecules inducing multiple effects through separate G-protein-coupled receptors: the P2Y and the CysLT receptors. Here we show that GPR17, a Gi-coupled orphan receptor at intermediate phylogenetic position between P2Y and CysLT receptors, is specifically activated by both families of endogenous ligands, leading to both adenylyl cyclase inhibition and intracellular calcium increases. Agonist-response profile, as determined by [(35)S]GTPgammaS binding, was different from that of already known CysLT and P2Y receptors, with EC(50) values in the nanomolar and micromolar range, for CysLTs and uracil nucleotides, respectively. Both rat and human receptors are highly expressed in the organs typically undergoing ischemic damage, that is, brain, heart and kidney. In vivo inhibition of GPR17 by either CysLT/P2Y receptor antagonists or antisense technology dramatically reduced ischemic damage in a rat focal ischemia model, suggesting GPR17 as the common molecular target mediating brain damage by nucleotides and CysLTs. In conclusion, the deorphanization of GPR17 revealed a dualistic receptor for two endogenous unrelated ligand families. These findings may lead to dualistic drugs of previously unexplored therapeutic potential.

Amino Acid Sequence↗
PubMed2006

Reciprocal congenic lines for a major stroke QTL on rat chromosome 1.

We previously identified a quantitative trait locus (QTL) for stroke proneness between the kallikrein (Klk) and Mt1pa markers on rat chromosome 1. To gain functional insights, we constructed congenic strains by introgressing either the whole or selected chromosomal segments from the stroke-prone (SHRsp) onto the stroke-resistant (SHRsr) spontaneously hypertensive rat genome and vice versa. The phenotype was the latency to develop stroke under a Japanese high-salt, low-potassium diet for 3 mo [known as Japanese diet (JD)]. Blood pressure (BP) was measured by tail cuff throughout the experiment. Urinary protein excretion was monitored in all lines under JD. The SHRsp-derived lines carrying the SHRsr allele, and particularly the D1Rat134-Mt1pa chromosomal segment, had a significant delay of stroke occurrence and improved survival compared with SHRsp (P < 0.001). On the other hand, a significant occurrence of stroke events (20%) was detected in the reciprocal lines by the end of the 3-mo treatment with JD (P = 0.003). The stroke phenotype was also associated with increased proteinuria. Our results underscore the functional importance of the Chr 1 stroke QTL. Furthermore, they underscore the utility of stroke/congenic lines in dissecting the genetics of stroke.

Alleles↗
PubMed2006

Activation of NF-kB and ERK1/2 after permanent focal ischemia is abolished by simvastatin treatment.

We investigated the effects of simvastatin treatment on the expression of IL-1beta and MCP-1, the activity of NF-kB, and the signaling pathways related to NF-kB activation in a rat model of permanent middle cerebral artery occlusion (pMCAO). IL-1beta and MCP-1 expression, determined using RT-PCR, was enhanced by pMCAO; this effect was inhibited by the administration of simvastatin before ischemia. Pre-treatment with simvastatin abolished the ischemia-induced activation of NF-kB observed in vehicle-treated animals. The evaluation of signal transduction pathways, including extracellular signal-regulated kinase (ERK1/2), SAPK/JNK 46/54 and p38, indicated that only ERK1/2 phosphorylation was enhanced by ischemia, and this activation was prevented by simvastatin. ERK1/2-inhibitor, U0126, reduced brain ischemia but not cytokine induction. These results provide evidence that the HMG-CoA reductase inhibitor induces its effect in the protection of ischemic brain damage with a more complex mechanism which also involve anti-inflammatory properties rather than simple inhibition of ERK1/2 signaling pathway.

Animals↗
PubMed2005

Rosuvastatin, but not simvastatin, provides end-organ protection in stroke-prone rats by antiinflammatory effects.

OBJECTIVE: Brain abnormalities, preceded by a systemic inflammation, develop in spontaneously hypertensive stroke-prone rats (SHRSP). In this model, we investigated whether the hydrophilic statin, rosuvastatin, influences the development of inflammation associated with brain abnormalities. Because differences in hydrophilicity/hydrophobicity contribute to the differences in statin pharmacology, we also evaluated the effects of simvastatin, a lipophilic molecule METHODS AND RESULTS: SHRSP, fed a high-salt diet, were treated long-term with vehicle or rosuvastatin (1 and 10 mg/kg per day). Brain abnormalities developed after 40+/-5 days and after 60+/-5 days of salt loading, in vehicle-treated and in rosuvastatin-treated (1 mg/kg per day) SHRSP, respectively. After 100 days of treatment, no damage was detectable in 30% of the rats treated with the highest dose of the drug. In comparison with vehicle-treated SHRSP, rosuvastatin treatment attenuated the transcription of monocyte chemoattractant protein-1, transforming growth factor-beta1, IL-1beta, and tumor necrosis factor-alpha in the kidney, and of P-selectin in brain vessels and increased the transcription of endothelial nitric oxide synthase mRNA in the aorta. Urinary excretion of acute-phase proteins increased with time in vehicle-treated animals but remained negligible in drug-treated animals. These effects are independent of changes in physiological parameters. Treatment of SHRSP with simvastatin (2 to 20 mg/kg per day) did not exert any protective effect. CONCLUSIONS: Rosuvastatin attenuates inflammatory processes associated with cerebrovascular disease.

Acute-Phase Proteins↗
PubMed2005

Invited commentary.

Explore the source record for details and available documents.

Coronary Artery Bypass↗
PubMed2005

Anti-inflammatory properties of drugs acting on the renin-angiotensin system.

It is now well established that the activation of the renin-angiotensin system (RAS) is involved in the onset and progression of cardiovascular and renal diseases, and that its main effector, angiotensin II (Ang II) has major pro-inflammatory activity that induces the expression of cytokines, chemokines, adhesion molecules, growth factors and reactive oxygen species. By means of these actions, Ang II induces vascular inflammation, endothelial dysfunction and fibrosis, and participates in destabilizing atherosclerotic plaque and establishing chronic kidney diseases. Blocking the RAS by inhibiting Ang II generation or blocking angiotensin receptors reduces the morbidity and mortality associated with cardiovascular and renal disease beyond the levels due to the lowering of blood pressure, and these benefits are at least partially due to the reduction/prevention of both local and systemic inflammatory processes. The aim of this review is to describe the role of the RAS (and particularly Ang II) in initiating and maintaining these processes, and to summarize experimental and clinical evidence supporting the role of drugs acting on the RAS in preventing or modulating inflammation.

Angiotensin II↗
PubMed2004

Analysis of pathological events at the onset of brain damage in stroke-prone rats: a proteomics and magnetic resonance imaging approach.

Spontaneously hypertensive stroke-prone rats (SHRSP) develop brain abnormalities invariably preceded by the accumulation of acute-phase proteins in body fluids. This study describes the sequence of pathological events, and in particular the involvement of inflammation, at the onset of brain injury in this animal model. In SHRSP subjected to permissive dietary treatment, the appearance of brain damage and of altered permeability of the blood-brain barrier (BBB) was monitored over time by magnetic resonance imaging (MRI) after intravenous injection of gadolinium. The protein content in cerebrospinal fluid and brain extracts was analyzed by two-dimensional electrophoresis. Gadolinium diffusion showed impairment of the BBB after 42 +/- 3 days from the start of salt loading, simultaneously with the detection of brain abnormalities by MRI. Tissue lesions were initially localized at one or more small foci and then spread throughout the brain in the form of fibrinoid necrosis. This type of lesion is characterized by fibrin deposition, in particular around the vessels; loss of tissue texture; and infiltration of macrophages and lymphocytes. High levels of plasma-derived proteins of molecular mass up to >130 kDa were detected in the cerebrospinal fluid after MRI had revealed brain abnormalities. Plasma proteins extravasated from brain vessels were immunodetected in tissue homogenates from affected areas. The results obtained in this study provide new insights into the pathogenesis of the spontaneous brain damage in SHRSP and in particular on the involvement of the inflammatory cascade. These studies may be useful in evaluating new pharmacological strategies aimed at preventing/treating brain diseases.

Animals↗
PubMed2004

Anti-inflammatory effects of AT1 receptor blockade provide end-organ protection in stroke-prone rats independently from blood pressure fall.

Spontaneously hypertensive stroke-prone rats (SHRSP) develop hypertension and systemic inflammation, with subsequent brain and renal disorders and early death. We tested the hypothesis that valsartan, an angiotensin II type 1 (AT1) receptor antagonist, exerts protective effects in SHRSP through its anti-inflammatory properties, even in the absence of a blood pressure-lowering effect. SHRSP fed a high-salt diet were treated with vehicle or valsartan (1-10 mg/kg/day). The vehicle-treated rats developed hypertension, proteinuria, progressive kidney disease, and, 40 +/- 5 days from the beginning of the treatment, brain damage as visualized by magnetic resonance imaging. Rats treated with 1 mg/kg/day valsartan developed brain damage after 61 +/- 3 days (p <0.01 versus vehicle-treated rats). No damage showed after 100 days in 80% of the rats treated with 10 mg/kg/day. Valsartan treatment preserved renal structure, by preventing the infiltration of inflammatory cells, and lowered renal expression of monocyte chemoattractant protein-1, transforming growth factor-beta1, and interleukin-1beta, compared with vehicle-treated SHRSP. Urinary excretion of acute-phase proteins increased in the latter but remained negligible in the drug-treated animals. Furthermore, valsartan exerted protective effects also when given after established proteinuria. In SHRSP, blockade of AT1 receptor with valsartan prevents the development of proteinuria, delays the appearance of brain damage, preserves renal structure, and increases survival under stressful conditions. Valsartan exerts its beneficial effects independently of any blood pressure fall and by means of broad anti-inflammatory actions both at local and at systemic levels. These observations indicate that the administration of AT1 receptor antagonists may be useful in pathological situations in which an anti-inflammatory effect is required.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2004

Pentoxifylline prevents spontaneous brain ischemia in stroke-prone rats.

Anti-inflammatory properties of pentoxifylline (PTX) have recently been described. Spontaneously hypertensive stroke-prone rats (SHRSP) constitute an animal model that develops an inflammatory condition that precedes the appearance of brain abnormalities. The aim of the present investigation was to assess: 1) the efficacy of PTX treatment in protecting the neural system in SHRSP, and 2) how its anti-inflammatory properties might be involved in this effect. Male SHRSP fed with a permissive diet received no drug or PTX (100 or 200 mg/kg/day). Brain abnormalities detected by magnetic resonance imaging developed spontaneously in control rats after 42 +/- 3 days, whereas in rats treated with 100 mg/kg/day PTX, abnormalities developed in only 80% of the animals and only after 70 to 80 days. Treatment with a higher dose of PTX (200 mg/kg/day) completely protected the brain from abnormal development. The drug treatment prevented the accumulation of macrophages or CD4+ positive cells, the activation of glia in brain tissues, and the appearance of inflammatory proteins and thiobarbituric acid-reactive substances in body fluids. PTX treatment did induce a greater increase of serum tumor necrosis factor-alpha (TNF-alpha), but not of interleukin (IL)-1beta and IL-6 induced by in vivo administration of lipopolysaccharide (LPS), which suggests a protective role for TNF-alpha. PTX also exerted protective effects when it was administered after the first occurrence of proteinuria (>40 mg/day). These data indicate that PTX treatment dose-dependently prevents the occurrence of spontaneous brain damage by reducing inflammatory events. We also hypothesize that the increase of TNF-alpha by PTX treatment represents a protective mechanism in SHRSP.

Animals↗
PubMed2003

Cobalamin (vitamin B12)-deficiency-induced changes in the proteome of rat cerebrospinal fluid.

We studied the changes in the proteome of CSF (cerebrospinal fluid) in two animal models of Cbl (cobalamin) deficiency: TGX (totally gastrectomized) rats and rats fed a Cbl-D (Cbl-deficient) diet. Two-dimensional PAGE was used to detect qualitative and quantitative variations in proteins in the CSF samples. The peak increase in total CSF protein concentration was observed 4 months after TG (total gastrectomy) and after 6 months of eating a Cbl-D diet. There is a specific increase 4 months after TG in the spots corresponding to alpha1-antitrypsin and the de novo presence of thiostatin and haptoglobin beta. Cbl-replacement treatment in 4-month-TGX rats corrected these alterations in the CSF proteome. However, most of the CSF proteome alterations attenuated in Cbl-untreated 8-month-TGX rats and in rats fed a Cbl-D diet for 16 months. Transthyretin concentration varied slightly in the CSF of both types of Cbl-D rat, whereas the relative abundance of prostaglandin D synthase rose sharply in the CSF of the rats fed a Cbl-D diet for 16 months. We have demonstrated previously that the histological and ultrastructural CNS (central nervous system) damage in both types of Cbl-D rat appears within 2-3 months of Cbl deficiency, and thus appears to precede the alterations in the CSF proteome. The CSF proteome patterns of rats in which phlogosis was induced in or outside the CNS are quite different from those of the CSF of Cbl-D rats. All these findings demonstrate that the alterations in the CSF proteome of Cbl-D rats are specifically linked to Cbl deficiency.

Animals↗
PubMed2003

Prophylactic but not delayed administration of simvastatin protects against long-lasting cognitive and morphological consequences of neonatal hypoxic-ischemic brain injury, reduces interleukin-1beta and tumor necrosis factor-alpha mRNA induction, and does not affect endothelial nitric oxide synthase expression.

BACKGROUND AND PURPOSE: Prophylactic administration of simvastatin has been shown to protect against brain damage and its long-lasting behavioral consequences in neonatal rats. To establish the drug treatment window, we evaluated the effectiveness of simvastatin administered at different intervals before and after stroke. Furthermore, we determined whether simvastatin affected endothelial nitric oxide synthase (eNOS) or inflammatory cytokines in brain tissue or cholesterol levels in serum. METHODS: On postnatal day 7, male rats were subjected to hypoxia-ischemia (HI). The experiment included sham-operated controls and HI animals receiving daily saline or activated simvastatin (20 mg/kg) injections from postnatal day 1 to day 7 (HI-simvastatin 1-7 group), from postnatal day 4 to day 11 (HI-simvastatin 4-11 group), or from postnatal day 7 to day 14 (HI-simvastatin 7-14 group). The neuroprotective effect of simvastatin was evaluated at adulthood by means of behavioral and histological analyses. Cytokines and eNOS expression were assessed by reverse transcriptase-polymerase chain reaction and Western blotting. RESULTS: Animals in both the HI-simvastatin 1-7 and HI-simvastatin 4-11 groups performed better than HI rats in either the T-maze or the circular water maze and showed significantly attenuated brain damage. Expression of interleukin-1beta and tumor necrosis factor-alpha mRNA in cortex was significantly increased in HI but not in HI-simvastatin 1-7 animals. In the same brain area, simvastatin treatment did not affect the increase of eNOS expression observed after HI. CONCLUSIONS: These findings indicate that prophylactic but not delayed administration of simvastatin improves functional outcome in neonatal rat stroke. The reduced induction of cytokines suggests that the neuroprotective effect of simvastatin may be related to a dampening of the inflammatory response.

Animals↗
PubMed2003

Endogenous proteolytic activity in a rat model of spontaneous cerebral stroke.

We evaluated the expression of two extra-cellular protease systems in a model of spontaneous cerebrovascular pathology: spontaneously hypertensive stroke-prone rats (SHRSP). The appearance of brain damage in individual animals was imaged and followed by means of magnetic resonance imaging (MRI). In situ zymography of brain slices obtained 3 days after the appearance of brain damage showed an increase in plasminogen activator (PA)/plasmin activity that co-localised with the cerebral damage detected by MRI; there was also concomitant accumulation/activation of inflammatory cells in the damaged area. Proteolytic activity was inhibited by the urokinase-specific inhibitor amiloride but not by an antibody against tissue-type plasminogen activator (t-PA). SDS-PAGE zymography of brain extracts revealed the presence of 58 kDa plasminogen-dependent lysis areas in the ischemic and non-ischemic tissues, and a 33 kDa lysis area in ischemic tissue only. An antibody against t-PA inhibited the former, whereas the latter was inhibited by amiloride. The specific induction of urokinase-type plasminogen activator (u-PA) in the damaged tissue was further confirmed by the fact that both u-PA protein mass and mRNA were markedly increased in the damaged cerebral areas. Concomitant metalloproteinase-2 (MMP-2) activation was only observed in the damaged area. These data suggest that u-PA is expressed and selectively catalyses proteolysis in the injured area of spontaneous brain damage in SHRSP.

Animals↗
PubMed2003

Treatment with statins after induction of focal ischemia in rats reduces the extent of brain damage.

OBJECTIVE: In the present study, MRI has been used to investigate therapeutic intervention with statins in a model of permanent focal cerebral ischemia in rat. METHODS AND RESULTS: Brain ischemia was induced in rats by the permanent occlusion of middle cerebral artery (MCAO) and the brain infarct size followed up in alive animals 2, 24, and 48 hours after MCAO, using the trace of apparent diffusion coefficient [Tr(D)] maps and T2-weighted images. In vehicle-treated rats, the infarct volumes increased by 38.5% and 89% after 24 and 48 hours, respectively, compared with the damage detected at 2 hours after MCAO. Treatment with simvastatin (20 mg/kg) after MCAO prevented the increase in brain infarct volume occurring at 24 hours and induced a 46.6% reduction after 48 hours. This effect was similar to that observed when simvastatin was administered before the induction of focal ischemia. T2W-MRI images confirmed these findings. The neuroprotective effects of simvastatin were paralleled by an increase in endothelial NO synthase immunoreactivity, detectable in the brain of simvastatin-treated rats. CONCLUSIONS: Statins, in addition to their preventive effect on cerebral ischemia, exert a neuroprotective role in the attenuation of brain damage after acute stroke.

Animals↗
PubMed2002

Oxidized phospholipids inhibit cyclooxygenase-2 in human macrophages via nuclear factor-kappaB/IkappaB- and ERK2-dependent mechanisms.

OBJECTIVE: Oxidized low-density lipoproteins (ox-LDL) or their components suppress macrophage inflammatory response by down-regulating cytokine synthesis, nitric oxide synthase and inducible cyclooxygenase (Cox-2). This event is crucial for the pathophysiological process leading to the formation of atherosclerotic plaque. Our present study focused on the mechanisms through which oxidized phospholipids inhibit LPS-induced Cox-2 expression in human macrophages. METHODS: Macrophages were incubated with a mixture of oxidized fragmented phospholipids (ox-PAPC), present in modified LDL, and then exposed to LPS. Cox-2 was evaluated in terms of protein levels, mRNA and activity. RESULTS: Ox-PAPC dose-dependently inhibited Cox-2 protein, mRNA and activity by preventing NF-kappaB binding to DNA. This effect was consequent to alterations of the degradation pattern of IkappaBalpha. Moreover, ox-PAPC markedly prevented extracellular signal-regulated kinase (ERK2) activation, leading to Cox-2 expression, whereas activation of the transcription factor peroxisome proliferator-activated receptors (PPARs) was not influenced. CONCLUSION: ox-PAPC down-regulates LPS-induced Cox-2 expression in human macrophages by targeting both NF-kappaB/IkappaB and ERK2 pathways. An altered inflammatory response by macrophages within atheromata may contribute to the progression of atherosclerosis.

Cell Culture Techniques↗
PubMed2002

New insights into brain damage in stroke-prone rats: a nuclear magnetic imaging study.

BACKGROUND AND PURPOSE: The spontaneously hypertensive stroke-prone rat (SHRSP) is an animal model for a complex form of cerebrovascular pathology. MRI provides an efficient and noninvasive tool for studying the time course of brain damage. The aim of this study was to gain new insights into the pathological phenomena responsible for the occurrence of brain injury in SHRSP with the use of the apparent diffusion coefficient of water (ADC), one of the most efficient MRI parameters for detecting brain abnormalities. To this end, the pattern of ADC variation observed in SHRSP was compared with that of focal ischemia induced in both SHRSP and Sprague-Dawley rats. METHODS: Four groups of animals were studied: SHRSP developing spontaneous brain lesions fed with a salt-loaded (n=15, group 1) or standard diet (n=3, group 2) and Sprague-Dawley rats (n=8, group 3) and SHRSP (n=8, group 4) with permanent middle cerebral artery occlusion. ADC maps and T2-weighted images of brains were performed by MRI. After the rats were killed, the brains were removed and histologically processed. RESULTS: There was no decrease in ADC during spontaneous stroke in the SHRSP fed with a normal or salt-enriched diet, while both the SHRSP and Sprague-Dawley rats with middle cerebral artery occlusion showed a marked decrease that lasted for 24 to 48 hours. CONCLUSIONS: Cerebral ischemia cannot be considered a major factor in the onset of spontaneous brain lesions in SHRSP, which show only vasogenic edema after the beginning of the damage with no evidence of metabolic impairment.

Animals↗