Biomedical subjects

Domenico Spina

Publications and source records attributed to Domenico Spina.

At least 19 recordsLinked to original sources

PubMed2006

The pharmacology of two novel long-acting phosphodiesterase 3/4 inhibitors, RPL554 [9,10-dimethoxy-2(2,4,6-trimethylphenylimino)-3-(n-carbamoyl-2-aminoethyl)-3,4,6,7-tetrahydro-2H-pyrimido[6,1-a]isoquinolin-4-one] and RPL565 [6,7-dihydro-2-(2,6-diisopropylphenoxy)-9,10-dimethoxy-4H-pyrimido[6,1-a]isoquinolin-4-one].

The pharmacology of two novel, trequinsin-like PDE3/4 inhibitors, RPL554 [9,10-dimethoxy-2(2,4,6-trimethylphenylimino)-3-(N-carbamoyl-2-aminoethyl)-3,4,6,7-tetrahydro-2H-pyrimido-[6,1-a]isoquinolin-4-one] and RPL565 [6,7-dihydro-2-(2,6-diisopropylphenoxy)-9,10-dimethoxy-4H-pyrimido[6,1-a]isoquinolin-4-one], has been investigated in a number of in vitro and in vivo assays. Electrical field stimulation-induced contraction of guinea pig superfused isolated tracheal preparations was significantly inhibited by RPL554 (10 microM) and RPL565 (10 microM) (percentage control; 93 +/- 1.2 and 84.4 +/- 2.7, respectively). Contractile responses were suppressed for up to 12 h after termination of superfusion with RPL554 demonstrating a long duration of action. RPL554 and RPL565 inhibited, in a concentration-dependent manner, lipopolysaccharide-induced tumor necrosis factor alpha release from human monocytes [IC50; 0.52 microM (0.38-0.69) and 0.25 microM (0.18-0.35), respectively] and proliferation of human mononuclear cells to phytohemagglutinin [IC50; 0.46 microM (0.24-0.9) and 2.90 microM (1.6-5.4), respectively]. The inhibitory effect of these drugs in vitro was translated into anti-inflammatory activity in vivo. RPL554 (10 mg/kg) and RPL565 (10 mg/kg) administered orally significantly inhibited eosinophil recruitment following antigen challenge in ovalbumin-sensitized guinea pigs. Likewise, inhalation of dry powder containing RPL554 by conscious guinea pigs (25% in micronized lactose) 1.5 h before antigen exposure significantly inhibited the recruitment of eosinophils to the airways. Exposure of conscious guinea pigs to inhalation of dry powder containing RPL554 (2.5%) and RPL565 (25%) in micronized lactose significantly inhibited histamine-induced plasma protein extravasation in the trachea and histamine-induced bronchoconstriction over a 5.5-h period. Thus, RPL554 and RPL565 are novel, long-acting PDE 3/4 inhibitors exhibiting a broad range of both bronchoprotective and anti-inflammatory activities.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2006

Phosphodiesterase inhibitors.

Phosphodiesterases are a diverse family of enzymes that hydrolyse cyclic nucleotides and thus play a key role in regulating intracellular levels of the second messengers cAMP and cGMP, and hence cell function. Theophylline and papaverine have historically been used therapeutically and are known to be weak inhibitors of PDE, but to what extent this contributed toward their clinical efficacy was poorly defined. However, the discovery of 11 isoenzyme families and our increased understanding of their function at the cell and molecular level provides an impetus for the development of isoenzyme selective inhibitors for the treatment of various diseases. This review focuses on the development of PDE3 inhibitors for congestive heart failure, PDE4 inhibitors for inflammatory airways disease and most successfully, PDE5 inhibitors for erectile dysfunction.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2006

Mechanism of adenosine-induced airways obstruction in allergic guinea pigs.

Inhaled adenosine induces airway obstruction in asthmatic but not healthy subjects, a phenomenon that is also observed in various animal species when they are immunised to a relevant antigen, but which does not occur in naïve animals. The purpose of this study was to investigate the mechanisms of airway responsiveness to adenosine receptor agonists in anaesthetised allergic guinea pigs. Inhaled adenosine 5'-monophosphate (AMP), the A1-selective adenosine receptor agonist N6-cyclopentyladenosine (CPA) and ovalbumin all caused airway obstruction in allergic guinea pigs, but not naïve animals, as assessed by changes in total lung resistance. In contrast, the A(2a)-selective (CGS 21680; 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxoamido adenosine) and A3-selective (IB-MECA; 1-deoxy-1-[6-[[3-iodophenyl)-methyl]amino]-9H-purin-9-yl]-N-methyl-beta-D-ribofuranuronamide) adenosine receptor agonists failed to elicit airway obstruction in passively sensitised guinea pigs. Airway obstruction induced by AMP or CPA was not inhibited by the H1 receptor antagonist, mepyramine (1 mg kg(-1)) in passively sensitised guinea-pigs. In contrast, airway obstruction to ovalbumin was significantly inhibited by this antagonist. Airway obstruction induced by AMP and CPA was significantly inhibited in sensitised animals chronically treated with capsaicin. In contrast, airway obstruction to ovalbumin was not inhibited by this treatment. Airway obstruction induced by AMP, CPA and ovalbumin was significantly inhibited following bilateral vagotomy or pharmacological treatment with atropine (2 mg kg(-1)). Airway obstruction to CPA was inhibited by the adenosine A1 receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX: 0.1-1 mg kg(-1)). In contrast, airway obstruction to ovalbumin was not inhibited by this treatment. These observations provide evidence indicating that AMP and CPA may induce airway obstruction in sensitised guinea pigs by a mechanism unrelated to histamine release from mast cells, but is mediated via an adenosine A1-receptor-dependent mechanism. The inhibition of AMP- and CPA-induced airway obstruction by atropine, capsaicin and bilateral vagotomy suggests a neuronal-dependent mechanism with the particular involvement of capsaicin-sensitive nerves.

Adenosine↗

PubMed2005

Immunohistochemical localization of vanilloid receptor subtype 1 (TRPV1) in the guinea pig respiratory system.

Transient receptor potential vanilloid-1 (TRPV1) containing nerves are implicated in cough and bronchoconstriction although the significance of their documentation on non-neuronal cells is unclear. We have investigated the anatomical distribution and location of TRPV1 in an animal species often utilized in models of cough and airway inflammation. The distribution and localization of TRPV1 immunoreactivity in the lung was studied using confocal microscopy. Double labelling were carried out using the panaxonal marker, protein gene product 9.5 (PGP) and the neuropeptide substance P. TRPV1 was localized to fine axons within the epithelium of the trachea, however this represented only a fraction of the total axonal innervation of the epithelium. TRPV1 immunoreactive axons were also found in and around subepithelial regions of the airways, including smooth muscle and blood vessels and within the lower airways, found in the vicinity of bronchi and bronchioles, and in and around alveolar tissue. TRPV1 in the epithelium of the trachea was co-localized with substance P containing axons, although TRPV1 immunoreactive neuropeptide negative axons were also discernible. We found evidence for TRPV1 localization to axons throughout the respiratory tract. The distribution was heterogeneous and represented a fraction of the total neuronal innervation of the airways. No TRPV1 was found localized to airway epithelial cells. TRPV1 was often co-localized with the sensory neuropeptide substance P but there was evidence of TRPV1 positive neurones that did not express substance P. This suggests a role for TRPV1 in the airway that is independent of sensory neuropeptides.

Animals↗

PubMed2005

Selective phosphodiesterase 4 inhibitors in the treatment of allergy and inflammation.

Phosphodiesterase (PDE)4 inhibitors are a novel class of drugs in development for the treatment of inflammatory airways diseases, including asthma, allergic rhinitis and chronic obstructive pulmonary disease. PDE4 inhibitors are potent anti-inflammatory agents both in vitro and in vivo, but few have successfully proceeded to phase II and III clinical trials, as a result of insufficient clinical efficacy and unacceptable side effects, including nausea and emesis, which have hampered their progression. A greater understanding of the molecular biology of PDE4 has led to the development of efficacious compounds with fewer side effects. This review focuses on how selective PDE4 inhibitors can advance the treatment of airways diseases and deal with the challenges that lie ahead.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2004

Platelet P-selectin is required for pulmonary eosinophil and lymphocyte recruitment in a murine model of allergic inflammation.

Platelets are necessary for lung leukocyte recruitment in a murine model of allergic inflammation, and platelet-leukocyte aggregates are formed in circulating blood of patients with asthma after allergen exposure. However, it is unknown how platelets induce pulmonary leukocyte recruitment in asthma. Here, we have investigated the importance of platelet adhesion molecule expression on pulmonary eosinophil and lymphocyte recruitment and on leukocyte CD11b and very late antigen (VLA)-4 expression in mice. Pulmonary leukocyte recruitment in platelet-depleted mice (sensitized and exposed to ovalbumin) transfused with fixed, unstimulated platelets (FUSPs) was abolished, whereas transfusion with platelets stimulated and fixed (FSPs), expressing P-selectin and P-selectin glycoprotein ligand-1 (PSGL-1), restored eosinophil and lymphocyte recruitment. Transfusion with platelets from P-selectin-deficient mice, or with FSPs stimulated in the presence of a blocking anti-P-selectin antibody, were unable to restore pulmonary leukocyte recruitment. Flow cytometric analysis revealed increased expression of CD11b and VLA-4 on leukocytes attached to platelets after allergen exposure, and CD11b expression on leukocytes was suppressed in thrombocytopenic mice but was restored with the transfusion of FSPs, but not FUSPs, a phenomenon concurrent with the formation of platelet-leukocyte complexes. P-selectin expression on the surfaces of platelets is a major requirement for pulmonary eosinophil and lymphocyte recruitment, allowing circulating platelets to bind to and stimulate leukocytes for endothelial attachment.

Animals↗

PubMed2004

The pharmacology of cough.

Cough is an indispensable defensive reflex. Although generally beneficial, cough is also a common symptom of diseases such as asthma, chronic obstructive pulmonary disease (COPD) and lung cancer. Cough remains a major unmet medical need and, although the centrally acting opioids have remained the antitussive drug of choice for decades, such opioids possess many unwanted side-effects. However, new research into the behaviour of airway sensory nerves has provided greater insight into the mechanisms of cough and new avenues for the discovery of novel non-opioid antitussive drugs. In this article, the pathophysiological mechanisms of cough and the implications of this research for the development of novel antitussive drugs will be discussed. A poster depicting the pharmacology of cough is available online and in print as to this article.

Antitussive Agents↗

PubMed2004

Statistical methods in G-protein-coupled receptor research.

In this chapter we provide an introduction to statistical methods appropriate in G-protein-coupled receptor research, including examples. Topics covered include the choice of appropriate averages and measures of dispersion to summarize data sets, and the choice of tests of significance, including t-tests and one- and two-way analysis of variance (ANOVA) plus posttests for normally distributed (Gaussian) data and their nonparametric equivalents. Techniques for transforming non-normally distributed data to more Gaussian distributions are discussed. Concepts of statistical power, errors, and the use of these in determining the optimal size of experiments are considered. Statistical aspects of linear and nonlinear regression are discussed, including tests for goodness-of-fit to the chosen model and methods for comparing fitted lines and curves.

Analysis of Variance↗

PubMed2004

The potential of PDE4 inhibitors in respiratory disease.

Glucocorticosteroids remain the gold standard therapy for the prophylactic treatment of asthma. Concerns regarding its long-term use particularly in young children has provided an impetus for discovering novel anti-inflammatory molecules with high tolerability and clinical efficacy. Whilst for chronic obstructive pulmonary disease (COPD), there exist no pharmacological treatment for the prevention of decline in lung function. Targeting phosphodiesterase (PDE)4 is one example of this approach and inhibitors of this enzyme are the most advanced drug class in the respiratory pipeline. A number of potent PDE4 inhibitors have undergone clinical trials with moderate success. Tolerability and clinical efficacy issues have dampened enthusiasm in this area. However, with the prospect of newer potent and side effect free inhibitors on the horizon give this area guarded optimism. This review will summarise the most recent information concerning the effectiveness of PDE4 inhibitors as novel anti-inflammatory agents for the treatment of respiratory diseases.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2003

Platelets are necessary for airway wall remodeling in a murine model of chronic allergic inflammation.

Asthma is associated with airway remodeling. Evidence of platelet recruitment to the lungs of asthmatics after allergen exposure suggests platelets participate in various aspects of asthma; although their importance is unknown in the context of airway remodeling, their involvement in atherosclerosis is established. Studies from our laboratory have shown a requirement for platelets in pulmonary leukocyte recruitment in a murine model of allergic lung inflammation. Presently, the effects of platelet depletion and corticosteroid administration on airway remodeling and lung function were examined. Ovalbumin (OVA)-sensitized mice, exposed to aerosolized OVA for 8 weeks, demonstrated epithelial and smooth muscle thickening, and subepithelial reticular fiber deposition in the distal airways. The depletion of platelets via an immunologic (antiplatelet antisera) or nonimmunologic (busulfan) method, markedly reduced airway remodeling. In contrast, dexamethasone administration did not affect epithelial thickening or subepithelial fibrosis, despite significantly inhibiting leukocyte recruitment. Thus, pathways leading to certain aspects of airway remodeling may not depend on leukocyte recruitment, whereas platelet activation is obligatory. OVA-sensitized mice exhibited airway hyperresponsiveness (AHR) compared with sham-sensitized mice following chronic OVA exposure. Neither platelet depletion nor dexamethasone administration inhibited chronic AHR; thus, mechanisms other than inflammation and airway remodeling may be involved in the pathogenesis of chronic AHR.

Adrenal Cortex Hormones↗

PubMed2003

Pharmacology of a new cyclic nucleotide phosphodiesterase type 4 inhibitor, V11294.

V11294 is a new cyclic nucleotide phosphodiesterase type 4 (PDE4) inhibitor of the rolipram class. In this report we present the pharmacological profile of V11294. V11294 inhibited PDE4 isolated from human lung with IC(50) 405 nM, compared to 3700 nM for rolipram. In contrast, V11294 inhibition of human PDE3 and PDE5 occurred only at concentrations greater than 100,000 nM. Like rolipram, V11294 inhibited PDE4D more potently than other PDE4 subtypes. V11294, when incubated with human anticoagulated whole blood in vitro, or administered to mice, caused increased cAMP concentration, consistent with inhibition of PDE4. V11294 inhibited lectin-induced proliferation and lipopolysaccharide-induced TNFalpha synthesis by human adherent monocytes in vitro and inhibited lipopolysaccharide-induced TNFalpha synthesis in mice. V11294 caused relaxation of guinea pig isolated trachea and inhibited allergen-induced bronchoconstriction and eosinophilia in guinea pigs at doses of 1 and 3 mg/kg, p.o. In ferrets, V11294 was not emetogenic at doses up to 30 mg/kg, p.o., despite plasma concentration reaching 10-fold the IC(50) for PDE4. In contrast, rolipram induced severe retching and vomiting at 10 mg/kg, p.o. In conclusion, V11294 is an orally active PDE4 inhibitor that exhibits antiinflammatory activity in vitro, and in vivo at doses that are not emetogenic.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2003

Platelets are essential for leukocyte recruitment in allergic inflammation.

BACKGROUND: The role of platelets in inflammation is recognized but poorly characterized, and little is known of their interaction with leukocytes. However, platelet-leukocyte interactions have been demonstrated in cardiovascular disease, culminating in enhanced leukocyte recruitment. OBJECTIVES: This study was undertaken to assess the possibility and potential role of similar phenomena occurring in asthmatic patients, a murine model of allergic inflammation, and in vitro adhesion studies. METHODS: Asthmatic patients had blood taken at various time points to document the degree of leukocyte activation and the presence of platelet-leukocyte aggregates through FACS analysis before and after allergen exposure. Similar studies were carried out in mice exposed to allergen after previous sensitization, with some groups being selectively depleted of platelets through both an immunologic (antiplatelet antiserum) and nonimmunologic (busulfan) method. Additionally, lavage fluid and airway tissue were analyzed to assess the degree of pulmonary leukocyte recruitment. The importance of platelets on leukocyte adhesion to the endothelium was then assessed with in vitro incubation of radiolabeled leukocytes in the presence of activated platelets on cultured human vascular endothelial cells. RESULTS: We have observed circulating platelet-leukocyte aggregates in the blood of allergic asthmatic patients during the allergen-induced late asthmatic response and in sensitized mice after allergen exposure. In platelet-depleted mice infiltration of leukocytes into airways after allergen challenge was significantly reduced and could be restored by means of infusion of platelets from allergic animals, indicating an essential role for platelets in leukocyte recruitment. CD11b expression on leukocytes involved in aggregates with platelets, although not on free leukocytes, was upregulated. Furthermore, the presence of autologous platelets augmented the adhesion of human polymorphonuclear leukocytes to cultured vascular endothelial cells, an effect that was found to be endothelial cell dependent and to involve platelet activation. CONCLUSION: These results suggest that platelet participation in cell recruitment occurs at the level of the circulation and might involve the priming of leukocytes for subsequent adhesion and transmigration into tissues.

Adult↗

PubMed2003

Theophylline and PDE4 inhibitors in asthma.

Over the past three decades, beta -adrenoceptor agonists and glucocorticosteroids have formed the mainstay of treatment for patients with asthma; during this time, only one new drug class, leukotriene receptor antagonists, have been introduced. Theophylline has also been used in the treatment of patients with asthma, although there is a perception that this drug does not offer the patient any advantages over conventional therapeutic strategies. However, a number of clinical studies have documented the efficacy of this orally active drug. The mechanism by which theophylline exerts its well recognized antiinflammatory activity remains to be established but, if explained, could lead to newer drug development with greater efficacy. The development of phosphodiesterase (PDE)4 inhibitors is one such approach, and recent studies have demonstrated the potential utility of this new drug class for the treatment of patients with asthma.(2)

Administration, Oral↗

PubMed2003

Phosphodiesterase-4 inhibitors in the treatment of inflammatory lung disease.

Phosphodiesterases (PDE) belong to an important family of proteins that regulate the intracellular levels of cyclic nucleotide second messengers. Targeting PDE with selective inhibitors may offer novel therapeutic strategies in the treatment of various conditions, and in the context of respiratory disease these include asthma and chronic obstructive pulmonary disease (COPD). The rationale for such an approach stems, in part, from the clinical efficacy of theophylline, an orally active drug that is purportedly a nonselective PDE inhibitor. In addition, intracellular cyclic adenosine monophosphate (cAMP) levels regulate the function of many of the cells thought to contribute to the pathogenesis of respiratory diseases such as asthma and COPD, and these cells also selectively express PDE4. This has offered pharmaceutical companies the opportunity to selectively targeting these enzymes for the treatment of these diseases. Finally, the success of targeting PDE5 in the treatment of erectile dysfunction provides clinical proof of concept for the targeting of PDE in disease. Whether a 'Viagra' of the airways can be found for the treatment of asthma and COPD remains to be seen, but positive results from recent clinical studies examining the efficacy of selective PDE4 inhibitors such as cilomilast and roflumilast offer some optimism. However, one of the major issues to be resolved is the tolerability profile associated with this drug class that is a consequence of PDE4 inhibition. While cilomilast and roflumilast have low emetic potential they are not free from emesis and various strategies are being investigated in the hope of developing a PDE4 inhibitor without this adverse effect.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2002

Asthma -- a need for a rethink?

Asthma is a major medical problem but, despite decades of research, the mechanisms that underlie this condition remain elusive. Although the eosinophil has been regarded as a cell that is central to the pathogenesis of asthma, the failure to abrogate asthma symptoms by novel treatments that are designed to suppress the recruitment of eosinophils to the airways challenges this dogma. Our approach to understanding bronchial asthma needs to be broadened to include alterations in the function of afferent nerves that supply airways. Changes in the activity of these nerves offer a possible mechanism by which asthmatic subjects are uniquely responsive to a wide range of physiological and chemical stimuli. Here, we review the current status of asthma research.

Animals↗

PubMed2002

Pharmacology of airway irritability.

Bronchial hyperresponsiveness is a characteristic feature of respiratory diseases of the lung, including asthma and chronic obstructive pulmonary disease (COPD). However, asthmatic subjects respond to a range of physiological and chemical insults that are otherwise innocuous in healthy subjects or in patients with COPD, suggesting that the mechanisms underlying this phenomenon are characteristic of the asthma phenotype. Increasingly, there is evidence of a role for airway nerves in irritable airways and pharmacological targeting of the pathways involved may lead to the development of novel treatments for this disease. In this context, the recent cloning of the vanilloid receptor may be a useful target for drug discovery in respiratory disease.

Afferent Pathways↗

PubMed2002

Airway nerves: neurotransmitter release.

A number of methods exist that allow one to study the pharmacology of neuropeptide release in the airways. Methods include in vitro organ bath techniques to measure neuropeptide release functionally as changes in smooth-muscle tone and direct measurement of neuropeptide release from airway tissue or cultured sensory neurones. The measurement of sensory neuropeptide release from afferent nerves has contributed greatly to our understanding of the role played by these nerves in the control of lung function.

Animals↗

PubMed2002

Characterization of the anandamide induced depolarization of guinea-pig isolated vagus nerve.

1. There is considerable interest in elucidating potential endogenously derived agonists of the vanilloid receptor and the role of anandamide in this regard has received considerable attention. In the present study, we have used an electrophysiological technique to investigate the mechanism of activation of vanilloid receptors in an isolated vagal preparation. 2. Both capsaicin and anandamide depolarized de-sheathed whole vagal nerve preparations that was antagonized by the VR1 antagonist, capsazepine (P<0.05) whilst this response was unaltered by the cannabinoid (CB1) selective antagonist SR141716A or the CB2 selective antagonist, SR144528, thereby ruling out a role for cannabinoid receptors in this response. 3. The PKC activator, phorbol-12-myristate-13-acetate (PMA) augmented depolarization to both anandamide and capsaicin and this response was significantly inhibited with the PKC inhibitor, bisindolylmaleimide (BIM) (P<0.05). 4. The role of lipoxygenase products in the depolarization to anandamide was investigated in the presence of the lipoxygenase inhibitor, 5,8,11-Eicosatriynoic acid (ETI). Depolarization to anandamide and arachidonic acid was significantly inhibited in the presence of ET1 (P<0.05). However, in the absence of calcium depolarization to anandamide was not inhibited by ETI. 5. Using confocal microscopy we have demonstrated the presence of vanilloid receptors on both neuropeptide containing nerves and nerves that did not stain for sensory neuropeptides. 6. These results demonstrate that anandamide evokes depolarization of guinea-pig vagus nerve, following activation of vanilloid receptors, a component of which involves the generation of lipoxygenase products. Furthermore, these receptors are distributed in both neuropeptide and non-neuropeptide containing nerves.

Action Potentials↗