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F Nicoletti

Publications and source records attributed to F Nicoletti.

At least 163 records · Page 9Linked to original sources
PubMed1996

Synergistic effect of deoxyspergualin (DSP) and cyclosporin A (CsA) in the prevention of spontaneous autoimmune diabetes in BB rats.

Dose-dependent side effects are frequently observed with immunosuppressive drugs of potential relevance for the immunotherapy of insulin-dependent diabetes mellitus (IDDM), such as CsA and DSP. If CsA and DSP acted synergistically in vivo, their combined use would allow using each compound at lower doses than those required when each drug is given in monotherapy. Consequently, dose-dependent side effects could be reduced and the therapeutic activity maintained or even enforced. Toward this end we studied the effects of combined treatment with CsA and DSP on the course of IDDM in the diabetes-prone (DP)-BB rat. The results show that two 'low' doses of CsA (2 mg/kg) and DSP (1 mg/kg) that are clinically ineffective in suppressing IDDM development in BB rats when administered alone under a prolonged prophylactic regimen (30-105 days old), may successfully prevent, but not cure, the disease when given contemporaneously under the same experimental conditions. The combined treatment was well tolerated, and no side effects were noticed. These data suggest that the combined use of CsA and DSP may deserve consideration for its possible application in the prevention/treatment of human IDDM and other autoimmune diseases.

Animals↗
PubMed1996

Interaction between A1 adenosine and class II metabotropic glutamate receptors in the regulation of purine and glutamate release from rat hippocampal slices.

Electrical stimulation of rat hippocampal slices evoked the release of excitatory amino acids and purines, as reflected by a time-dependent increase in the extracellular levels of glutamate and adenosine, as well as by the increased efflux of radioactivity in slices preloaded with both [14C]glutamate and [3H]adenosine. The evoked release of excitatory amino acids and purines was amplified when slices were exposed to 8-cyclopentyl-1,3-dipropylxanthine (a selective A1 adenosine receptor antagonist), (+)-alpha-methyl-4-carboxyphenylglycine [a mixed antagonist of metabotropic glutamate receptors (mGluRs)], or (2S,3S,4S)-2-methyl-2-(carboxycyclopropyl)glycine (a selective antagonist of class II mGluRs). In contrast, 2-chloro-N6-cyclopentyladenosine (CCPA; a selective A1 receptor agonist) or (2S,1R,2R,3R)-(2,3-dicarboxycyclopropyl)glycine (DCG-IV; a selective agonist of class II mGluRs) reduced the evoked release of excitatory amino acids and purines. CCPA and DCG-IV also reduced the increase in cyclic AMP formation induced by either forskolin or electrical stimulation in hippocampal slices. The inhibitory effect of CCPA and DCG-IV on release or cyclic AMP formation was less than additive. We conclude that the evoked release of excitatory amino acids and purines is under an inhibitory control by A1 receptors and class II mGluRs, i.e., mGluR2 or 3, which appear to operate through a common transduction pathway. In addition, although these receptors are activated by endogenous adenosine and glutamate, they can still respond to pharmacological agonists. This provides a rationale for the use of A1 or class II mGluR agonists as neuroprotective agents in experimental models of excitotoxic neuronal degeneration.

Adenosine↗
PubMed1996

Immortalized hypothalamic neurons express metabotropic glutamate receptors positively coupled to cyclic AMP formation.

We have characterized the expression pattern and pharmacological profile of activation of metabotropic glutamate receptors (mGluRs) in immortalized, gonadotropin releasing hormone (GnRH)-secreting GT1-7 cells, which represent a homogeneous cellular population of hypothalamic origin. These cells are known to respond to the mGluR agonist (1S,3R)-cyclopentanedicarboxylic acid (1S,3R-ACPD) with increased GnRH release. To establish which specific mGluR subtypes are expressed by GT1-7 cells, we used polyclonal antibodies raised against non-conserved regions of the carboxy-terminal domains of individual subtypes. The selectivity of these antibodies was tested in HEK 293 cells transiently transfected with each mGluR subtype. GT1-7 cells stained positively for the subtypes mGluR1a, -1b and -5 (belonging to group I mGluR2/3 (group II) and mGluR7 (group III). Agonists of group I mGluRs, including 1S,3R-ACPD, activated phosphoinositide hydrolysis in GT1-7 cells. This effect, however, was manifested only when cell density was low, and it disappeared when cells reached confluence. Stimulation of phosphoinositide hydrolysis could not therefore have been related to hormone secretion because 1S,3R-ACPD effectively released GnRH in confluent cultures. We then focused on group II and III mGluRs, which in transfected cells are negatively linked to adenylate cyclase activity. Unexpectedly, however, agonist which preferentially activate group II and III mGluRs increased both basal and forskolin-stimulated cAMP accumulation in GT1-7 cells. Stimulation of cAMP accumulation by mGluR agonists was not prevented by enzymatic depletion of endogenous adenosine, but was obliterated when cells were incubated with agonists of receptors positively coupled to adenylate cyclase, such as beta-adrenergic and prostaglandin E2 receptors. These results suggest that GT1-7 cells express a novel mGluR subtype positively coupled to adenylate cyclase, which shares the same transduction pathway of other classical receptors coupled with a Gs-type of GTP-binding protein.

Animals↗
PubMed1996

Improved survival and antagonistic effect of sodium fusidate on tumor necrosis factor alpha in a neonatal mouse model of endotoxin shock.

Unlike the antibiotics erythromycin and penicillin G, sodium fusidate (fusidin) pretreatment (80 mg/kg of body weight) increased the survival rate of neonatal BALB/c mice challenged with Salmonella enteritidis lipopolysaccharide. Fusidin also significantly reduced the plasma tumor necrosis factor alpha levels. Hence, fusidin may prove useful in the management of bacterial sepsis in humans.

Animals↗
PubMed1996

In vitro type-1 and type-2 cytokine production in systemic lupus erythematosus: lack of relationship with clinical disease activity.

OBJECTIVE: To investigate the relationship between disease activity and in vitro cytokine, soluble(s)CD23 and polyclonal and anti-DNA antibody production by PBMC from patients with active systemic lupus erythematosus (SLE). METHODS: Cytokines, sCD23 and immunoglobulins were estimated by ELISA in unstimulated and polyclonal mitogen-stimulated culture supernatants. RESULTS: PHA-induced IL-2 and IFN-gamma production were decreased, whereas spontaneous and PHA-induced IL-6 and IL-10 production were increased in cultures of SLE lymphocytes. Conversely, spontaneous and PHA-stimulated IL-4 and sCD23 production was comparable between patients and controls. Finally, we found an increase in in vitro spontaneous polyclonal and anti-DNA IgG secretion. CONCLUSIONS: We demonstrated an expanded type-2 cytokine profile with no correlation with parameters of disease activity.

Adult↗
PubMed1996

The effects of a nonimmunogenic form of murine soluble interferon-gamma receptor on the development of autoimmune diabetes in the NOD mouse.

Previous studies have shown that in vivo treatment with antiinterferon-gamma (anti-IFNgamma) monoclonal antibodies (mAbs) prevents the development of autoimmune diabetes in NOD mice. Although these findings anticipate that specific anti-IFNgamma therapies may be useful for the prevention/treatment of human insulin-dependent diabetes mellitus, there are several reasons why the use of anti-IFNgamma mAb may be difficult in the clinical setting. With the aim to develop alternative forms of specific anti-IFNgamma therapies, we recently produced a nonimmunogenic form of the soluble IFNgamma receptor (sIFNgammaR) that binds and neutralizes murine IFNgamma with an affinity higher than that of anti-IFNgamma mAb. In this study we compared the efficacy of sIFNgammaR to that of two anti-IFNgamma mAbs (XMG 1.2 and AN-18) in the prevention of spontaneous and accelerated (cyclophosphamide-induced) forms of autoimmune diabetes in NOD mice. The results show that in the spontaneous model, sIFNgammaR could prevent histological and clinical signs of autoimmune diabetes as efficiently as the two mAbs. Under ex vivo conditions, sIFNgammaR exhibited a more powerful modulatory effect than XMG 1.2 mAb on cytokine secretion from splenic lymphoid cells, which resulted in a significant reduction of Concanavalin A-induced IL-2 secretion and an augmented release of both unstimulated and lipopolysaccharide-induced IL-6. Moreover, although both mAbs were immunogenic and elicited formation of high titers of anti-rat IgG, sIFNgammaR did not induce antibody formation. Unexpectedly, in the cyclophosphamide-induced model, sIFNgammaR turned out to be less effective than either of the two anti-IFNgamma mAbs. Taken together, these data support the role of IFNgamma in the pathogenesis of NOD mice, but, more importantly, suggest that a nonimmunogenic approach is possible to the diminution of the effects of IFNgamma in this model.

Animals↗
PubMed1996

Fusidic acid and insulin-dependent diabetes mellitus.

Insulin-dependent diabetes mellitus (IDDM) is a major cause of morbidity and mortality from long-standing complications. The autoimmune nature of IDDM has encouraged use of immunosuppressive and antiinflammatory strategies to better preserve residual pancreatic beta-cell function at the time of diagnosis. Fusidic acid and its sodium salt, fusidin, is a relatively atoxic antibiotic used mainly in the treatment of staphylococcal infections. Recently, fusidin has been demonstrated to possess immunosuppressive functions in vitro and in vivo, and the drug has shown promise in preventing the disease in animal models of IDDM and in a preliminary trial in IDDM patients.

Animals↗
PubMed1996

(2S,1'S,2'S,3'R)-2-(2'-carboxy-3'-phenylcyclopropyl)glycine, a potent and selective antagonist of type 2 metabotropic glutamate receptors.

The pharmacological profile of (2S,1'S,2'S,3'R)-2-(2'-Carboxy-3'-phenylcyclopropyl)glycine (PCCG-IV) at metabotropic glutamate receptor (mGluR) subtypes mGluR1a, mGluR2, mGluR4a, and mGluR5 was examined. PCCG-IV potently antagonized glutamate-induced inhibition of forskolin-stimulated cAMP formation in baby hamster kidney cells expressing mGluR2 in a competitive manner (KB = 8.2 +/- 0.4 microM). PCCG-IV was a weak agonist at mGluR4a but inactive at the cloned phosphoinositide-coupled mGluRs (mGluR1a and mGluR5a). PCCG-IV was significantly more potent and selective as an antagonist at mGluR2 compared with previously described mGluR2 antagonists, including alpha-methyl-4-carboxyphenylglycine. In mice cortical neurons, PCCG-IV antagonized the neuroprotective effects of a selective mGluR2 agonist, (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine, at low doses (0.2-20 microM), whereas a higher dose of PCCG-IV (80 microM) was similarly neuroprotective to L-2-amino-4-phosphonobutanoate. The neuroprotective effect of PCCG-IV was blocked by an antagonist of mGluR4a, alpha-methyl-4-phosphonophenylglycine. Thus, PCCG-IV is a novel and useful tool for delineating the physiological roles of group II mGluRs in the central nervous system.

Animals↗
PubMed1995

Activation of class II or III metabotropic glutamate receptors protects cultured cortical neurons against excitotoxic degeneration.

Trans-1-aminocyclopentane-1,3-dicarboxylic acid, a mixed agonist of all metabotropic glutamate receptor (mGluR) subtypes, is known to produce either neurotoxic or neuroprotective effects. We have therefore hypothesized that individual mGluR subtypes differentially affect neurodegenerative processes. Selective agonists of subtypes which belong to mGluR class II or III, such as (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)-glycine (DCG-IV) (specific for subtypes mGluR4, 6 or 7), were highly potent and efficacious in protecting cultured cortical neurons against toxicity induced by either a transient exposure to N-methyl-D-aspartate (NMDA) or a prolonged exposure to kainate. In contrast, agonists that preferentially activate class I mGluR subtypes (mGluR1 or 5), such as quisqualate or trans-azetidine-2,3-dicarboxylic acid, were inactive. DCG-IV was still neuroprotective when applied to cultures after the toxic pulse with NMDA. This delayed rescue effect was associated with a reduction in the release of endogenous glutamate, a process that contributes to the maturation of neuronal damage. We conclude that agonists of class II or III mGluRs are of potential interest in the experimental therapy of acute or chronic neurodegenerative disorders.

Animals↗
PubMed1995

Biphasic effect of interferon-gamma in murine collagen-induced arthritis.

Interferon-gamma (IFN-gamma) exerts both enhancing and suppressing influences on collagen-induced arthritis (CIA), depending on the route and protocol of administration. To study the role of IFN-gamma on the autoimmune process of CIA, we treated DBA/1 mice with two different rat monoclonal antibodies (mAb) to murine IFN-gamma. Treatments, given twice weekly for 4 weeks, consisted of intraperitoneal injections of either mAb. In early treatments, starting from the day of immunization with type II collagen (CII), the severity of arthritis was reduced in both groups of anti-IFN-gamma-treated mice compared with control groups. Moreover, anti-CII antibody levels decreased in the sera of these mice. CIA was also down-regulated in mice treated from days 14 or 28 post immunization. In contrast, late treatments with anti-IFN-gamma mAb either induced aggravating effects, or did not affect the course of the disease. On the other hand, administration of high doses (8 x 10(4) U three times/week) of rat recombinant IFN-gamma exerted a transient increase of CIA severity. These findings suggest that IFN-gamma may play a critical role during both the induction and the course of CIA, first enhancing the immune response, and then regulating the arthritis process.

Animals↗
PubMed1995

Growth conditions differentially affect the constitutive expression of primary response genes in cultured cerebellar granule cells.

Cultured cerebellar granule cells underwent apoptotic degeneration when grown in medium containing 10 instead of 25 mM K+. Knowing that apoptosis is associated with changes in the expression of primary response genes, we have measured c-fos, zif/268, and c-jun mRNA levels during maturation of cultured granule cells grown in 10 or 25 mM K+. The constitutive expression of c-fos and zif/268 was differentially regulated by extracellular K+ concentration at 5 days of maturation in vitro (DIV), when cells grown under suboptimal conditions (i.e. in 10 mM K+) are committed to degenerate. At this stage, c-fos mRNA levels were detectable only in cultures grown in 25 mM K+, whereas zif/268 mRNA levels were dramatically elevated in cultures grown in 10 mM K+. This provides one of the few conditions in which c-fos and zif/268 are differentially regulated in nerve cells. Substantial changes in c-jun, or beta-actin mRNA levels were detectable only at 7 DIV, when the percentage of apoptotic cells had already reached a plateau in cultures grown in 10 mM K+. We speculate that changes in the expression of zif/268 are important in the gene program associated with the induction of apoptosis by trophic deprivation in cultured neurons.

Animals↗
PubMed1995

Activation of metabotropic glutamate receptors coupled to inositol phospholipid hydrolysis amplifies NMDA-induced neuronal degeneration in cultured cortical cells.

We have studied the influence of class I metabotropic glutamate receptors (mGluRs) on excitotoxic neuronal degeneration in cultured murine cortical neurons grown on a monolayer of astrocytes. These cultures expressed high levels of mGluR5 mRNA, which were comparable to those found in RNA extracts from cerebral cortex. Cortical neurons in mixed cultures were heavily stained with antibodies raised against mGluR5 and were also stained--albeit to a much lower extent--with mGluR1a but not with mGluR1b or c antibodies. Preferential agonists of class I mGluRs, such as quisqualate, 3,5-dihydroxyphenylglycine (DHPG), and trans-azetidine-2,4-dicarboxylic acid (t-ADA), as well as the mixed mGluR agonist, 1S,3R-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) all stimulated PPI hydrolysis in cultured cortical cells. The potency of N-methyl-D-aspartate (NMDA) in inducing neuronal degeneration was substantially enhanced when the drug was coincubated with quisqualate, DHPG or t-ADA during a 10-min pulse (paradigm of "fast" toxicity). None of the mGluR agonists influenced neuronal viability by itself. The amplification of NMDA toxicity by quisqualate or DHPG was attenuated by a series of protein kinase C (PKC) inhibitors, suggesting that class I mGluRs operate, at least in part, through activation of PKC. Quisqualate and, in particular, DHPG enhanced excitoxic neuronal degeneration even when applied after the toxic pulse with NMDA. This action is likely to occur early in the maturation of excitotoxic damage, because the functional activity of class I mGluRs was substantially reduced at 2 or 3 hr after the NMDA pulse. These results suggest that activation of class I mGluRs enhances NMDA-receptor mediated neuronal toxicity and encourage the search for selective antagonists for the experimental therapy of acute or chronic neurodegenerative diseases.

Amino Acid Sequence↗
PubMed1995

Activation of metabotropic glutamate receptors prevents neuronal apoptosis in culture.

Cultured granule cells grown in serum-containing medium with a "low K+" concentration (10 mM) underwent apoptosis after maturation for 5 days in vitro (5 DIV), a time that coincides with the developmental decline in the activity of metabotropic glutamate receptors (mGluRs) coupled to polyphosphoinositide hydrolysis. The mGluR agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) prevented the development of low K(+)-induced apoptosis and the presence of the drug was critical at 6 and 7 DIV, i.e., after the drop of mGluR activity. The neuroprotective action of 1S,3R-ACPD was prevented by the mGluR antagonist (RS)-alpha-methyl-4-carboxyphenylglycine (MCPG) and was mimicked by N-methyl-D-aspartate or carbamylcholine but not by agonists of the mGluR subtypes negatively linked to adenylyl cyclase. In cultures treated either with Li(+)-which reduced polyphosphoinositide response to concentrations of glutamate (5 microM) that approximate those physiologically present in the incubation medium--or MCPG, the development of low K(+)-induced apoptosis already occurred at 4 DIV. Thus, the activation of mGluRs coupled to polyphosphoinositide hydrolysis by endogenous glutamate could contribute to protect cultured granule cells against apoptosis during early stages of maturation.

Animals↗
PubMed1995

[3H]aniracetam binds to specific recognition sites in brain membranes.

[3H]Aniracetam bound to specific and saturable recognition sites in membranes prepared from discrete regions of rat brain. In crude membrane preparation from rat cerebral cortex, specific binding was Na+ independent, was still largely detectable at low temperature (4 degrees C), and underwent rapid dissociation. Scatchard analysis of [3H]aniracetam binding revealed a single population of sites with an apparent KD value of approximately 70 nM and a maximal density of 3.5 pmol/mg of protein. Specifically bound [3H]aniracetam was not displaced by various metabolites of aniracetam, nor by other pyrrolidinone-containing nootropic drugs such as piracetam or oxiracetam. Subcellular distribution studies showed that a high percentage of specific [3H]aniracetam binding was present in purified synaptosomes or mitochondria, whereas specific binding was low in the myelin fraction. The possibility that at least some [3H]aniracetam binding sites are associated with glutamate receptors is supported by the evidence that specific binding was abolished when membranes were preincubated at 37 degrees C under fast shaking (a procedure that substantially reduced the amount of glutamate trapped in the membranes) and could be restored after addition of either glutamate or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) but not kainate. The action of AMPA was antagonized by DNQX, which also reduced specific [3H]aniracetam binding in unwashed membranes. High levels of [3H]aniracetam binding were detected in hippocampal, cortical, or cerebellar membranes, which contain a high density of excitatory amino acid receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Placental thrombosis and fetal loss after passive transfer of mouse lupus monoclonal or human polyclonal anti-cardiolipin antibodies in pregnant naive BALB/c mice.

In the present study we evaluated the effect of passive transfer of a mouse monoclonal (CAM) or a human polyclonal anti-cardiolipin IgG on pregnancy outcome in BALB/c mice. The mice were immunized through the tail vein immediately after mating with 10 micrograms of monoclonal or polyclonal anti-cardiolipin antibodies. Two other groups of mice were given a mouse irrelevant monoclonal antibody or normal human polyclonal IgG respectively, at the same dose. In mice immunized with monoclonal or polyclonal anti-cardiolipin antibody we observed a significant increase in the number of fetal resorptions and a significant reduction of the mean weights of the embryos and the placentas. In mice immunized with CAM we also found a significant decrease in the number of healthy pups, while mice infused with human aCL antibody expressed a significant reduction in the fecundity rate. The histological examination showed widespread thrombosis and necrosis in the placentas derived from the mice immunized with the anti-cardiolipin antibodies. The model supports a possible direct pathogenetic effect of anti-phospholipid antibodies in recurrent fetal loss and points out that thrombotic events at placental level can be instrumental in the pathogenesis of the obstetric complications.

Animals↗
PubMed1995

Effects of sodium fusidate in animal models of insulin-dependent diabetes mellitus and septic shock.

We have evaluated the effects of the novel immunosuppressant sodium fusidate (fusidin) in the non-obese diabetic (NOD) mouse and in D-galactosamine (D-Gal)-presensitized BALB/c mice challenged with the bacterial superantigen, Staphylococcus aureus enterotoxin B (SEB) or with the endotoxin, Escherichia coli lipopolysaccharide (LPS). The NOD mouse model has clinical and histoimmunological features similar to those of human insulin-dependent diabetes mellitus (IDDM). The SEB- and LPS-treated BALB/c mouse models exhibit pathogenic similarities with human septic shock conditions. In the NOD mouse, fusidin suppressed the spontaneous development of insulitis (mean inhibition 73%) and hyperglycaemia (IDDM incidence 25% versus 0%) when administered at 40 mg/kg five times weekly for 8 consecutive weeks from the fourth week of age; concurrently treated animals exhibited reduced percentages of splenic T lymphocytes. This anti-diabetogenic effect was confirmed in the accelerated model of diabetes induced in the NOD mouse with cyclophosphamide (CY) (IDDM incidence 55% versus 21-6% using dosages of fusidin from 40 to 80 mg/kg five times weekly); protection from IDDM development was achieved even when the drug (80 mg/kg/day) was first administered 7 days after CY challenge. In contrast, fusidin did not reverse hyperglycaemia when administered to CY-treated animals within 3 days of IDDM development. In the two models of septic shock, prophylactic treatment with fusidin, 80 mg/kg given three times for 2 days prior to D-Gal/SEB or D-Gal/LPS challenge, drastically reduced the lethality compared with D-Gal/buffer-treated mice. This effect may depend on the inhibitory action of fusidin on the secretion of cytokines such as interferon-gamma and tumour necrosis factor-alpha, the serum levels of which were greatly diminished in the fusidin-treated mice (mean inhibition 50-90%). These results demonstrate that fusidin may have a role in the treatment of cell-mediated autoimmune diseases and cytokine-mediated infectious diseases in humans.

Animals↗