[Show abstract][Hide abstract] ABSTRACT: The optimization of oxazole-based PDE4 inhibitor 1 has led to the identification of both oral (compound 16) and inhaled (compound 34) PDE4 inhibitors. Selectivity against PDE10/PDE11, off target screening, and in vivo activity in the rat are discussed.
[Show abstract][Hide abstract] ABSTRACT: Spleen Tyrosine Kinase (SYK) is a key activator of signaling pathways downstream of multiple surface receptors implicated in asthma. SYK function has been extensively studied in mast cells downstream of the high affinity IgE-receptor (FcR1). Preclinical studies have demonstrated a role for SYK in models of allergic inflammation, but a role in airway constriction has not been demonstrated. Here we have utilized a potent and selective pharmacological inhibitor of SYK to determine the role of SYK in allergen mediated inflammation and airway constriction in preclinical models. Attenuation of allergic airway responses was evaluated in a rat passive anaphylaxis model, and rat and sheep inhaled allergen challenge models as well as an ex vivo model of allergen-mediated airway constriction in rats and Cynomolgus monkeys. Pharmacological inhibition of SYK dose-dependently blocked IgE-mediated tracheal extravasation in rat. In a rat ovalbumin-sensitized airway challenge model, oral dosing with a SYK inhibitor (SYKi) led to a dose-dependent reduction in lung inflammatory cells. Ex vivo analysis of allergen induced airway constriction in ovalbumin-sensitized Brown Norway rats showed complete attenuation with treatment of a SYK inhibitor as a well as a complete block of allergen-induced serotonin release. Similarly, allergen mediated airway constriction was attenuated in ex vivo studies from non-human primate lungs. Intravenous administration of a SYKi attenuated both early and late phase allergen-induced increases in airway resistance in an Ascaris-sensitive sheep allergen challenge model. These data support a key role for SYK signaling in mediating allergic airway responses.
American Journal of Respiratory Cell and Molecular Biology 07/2013; · 4.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Late phase airflow obstruction and reduction in forced vital capacity are characteristic features of human asthma. Airway microvascular leakage and lung edema are also present in the inflammatory phase of asthma, but the impact of this vascular response on lung functions has not been precisely defined. This study was designed to evaluate the role of increased lung microvascular leakage and edema on the late phase changes in forced vital capacity (FVC) and peak expiratory flow (PEF) in allergen-challenged Brown Norway rats using pharmacological inhibitors of the allergic inflammatory response. Rats were sensitized and challenged with ovalbumin aerosol and forced expiratory lung functions (FVC, PEF) and wet and dry lung weights were measured 48 h after antigen challenge. Ovalbumin challenge reduced FVC (63% reduction) and PEF (33% reduction) and increased wet (65% increase) and dry (51% increase) lung weights. The antigen-induced reduction in FVC and PEF was completely inhibited by oral treatment with betamethasone and partially attenuated by inhibitors of arachidonic acid metabolism including indomethacin (cyclooxygenase inhibitor), 7-TM and MK-7246 (CRTH2 antagonists) and montelukast (CysLT1 receptor antagonist). Antagonists of histamine H1 receptors (mepyramine) and 5-HT receptors (methysergide) had no significant effects indicating that these pre-formed mast cell mediators were not involved. There was a highly significant (P < 0.005) correlation for the inhibition of FVC reduction and increase in wet and dry lung weights by these pharmacological agents. These results strongly support the hypothesis that lung microvascular leakage and the associated lung edema contribute to the reduction in forced expiratory lung functions in antigen-challenged Brown Norway rats and identify an important role for the cyclooxygenase and lipoxygenase products of arachidonic acid metabolism in these responses.
[Show abstract][Hide abstract] ABSTRACT: Blood vessels of the nasal mucosa are richly innervated by sympathetic nerves and neural mechanism is of great interest in upper respiratory tract disorders. This study was designed to determine the role of α2-adrenoceptors and, more specifically, α2C-adrenoceptors, on neurogenic sympathetic vasoconstrictor responses in pig nasal mucosa, and to define the pharmacologic profile of a novel selective α2C-adrenoreceptor agonist.
Electrical field stimulation (EFS) was applied to nasal mucosa strips placed in an organ bath and attached to force displacement transducers for continuous recording of isometric tension. The affinity and functional activity of compound B for α2C-adrenoceptors were determined by binding analysis and the ability of compound B to stimulate [(35)S]GTPγS binding to the receptors. Compound B was also tested in a postjunctional α2C-adrenoreceptor bioassay.
EFS-induced contractions were partly blocked by the α2-adrenoreceptor antagonist yohimbine (41.1%) and the α2C-adrenoreceptor antagonist JP-1302 had no effect. The α2-adrenoreceptor agonist clonidine, but not compound B, exerted a significant blockade (70.6%). Compound B had high affinity (Ki = 18 nM), produced potent agonist (EC50 = 279 nM) and good efficacy (Emax = 73%) responses at the α2C-adrenoceptors, and displayed good functional agonist potency in the human saphenous vein α2C-adrenoreceptor bioassay (pD2 = 6.2).
(1) Neurogenic vasomotor contractility is largely regulated through an α-adrenergic mechanism; (2) pig nasal mucosa possesses post- and prejunctional α2-adrenoceptors; (3) the α2C-adrenoreceptor subtype does not seem to be involved; and (4) compound B is a novel, highly selective, and potent α2C-adrenoreceptor agonist.
American Journal of Rhinology and Allergy 03/2013; 27(2):84-90.
[Show abstract][Hide abstract] ABSTRACT: The introduction of A ring pyrazole modification to the hydrocortisone C-21 heteroaryl thioethers generated compounds with excellent transrepression potency (IL-8 inhibition) compared to their hydrocortisone analogs. However, the transcriptional transactivation activity of these compounds were considerably higher than the corresponding hydrocortisone analogs. Among all the compounds evaluated, a quinoxaline thioether modification demonstrated the best overall in vitro separation.
[Show abstract][Hide abstract] ABSTRACT: The prednisolone C-21 heteroaryl thioethers have been synthesized and evaluated in cell based transrepression and transactivation assays. Most of the compounds demonstrated weak transactivational activity in both human and rat tyrosineaminotransferase functional assay while keeping potent anti-inflammatory activity. The benzimidazole thioether 7 exhibited comparable anti-inflammatory activity and improved safety profile compared to the classical oral steroid prednisolone.
[Show abstract][Hide abstract] ABSTRACT: A series of C-21 mercapto derivatives of hydrocortisone have been synthesized and evaluated in cell based transrepression and transactivation assays. The benzothiazole derivative, compound 6 not only showed a dissociated profile in vitro functional assays but also a pharmacological profile in a Brown-Norway rat therapeutic index model of asthma that dissociated side effects (thymolysis) while maintaining efficacy against pulmonary inflammation and lung function.
[Show abstract][Hide abstract] ABSTRACT: A novel series of dual NK1/NK2 receptor antagonists, based on the 2-oxo-(1,4′-bipiperidine) template, has been prepared. Compound 10R is a potent dual NK1/NK2 antagonist and demonstrates excellent in vivo activity and good oral plasma levels in the dog.
[Show abstract][Hide abstract] ABSTRACT: Mometasone furoate (MF)/formoterol fumarate (F) combination is a new inhaIed corticosteroid/long-acting β₂-adrenergic agonist (ICS/LABA). The purpose of this study was to evaluate the effects of different dose combinations of MF/F on a variety of late-phase responses to aerosolized antigen challenge in ovalbumin sensitized Brown Norway rats. Late-phase responses were assessed by reductions in lung function, measured by forced vital capacity (FVC) and increased numbers of inflammatory cells and pro-inflammatory cytokines in the bronchoalveolar lavage (BAL) fluid of ovalbumin challenged rats. Intratracheal administration of MF/F 5 h before aerosolized ovalbumin challenge inhibited the increase in inflammatory cells, including eosinophils and levels of interleukin (IL)-4, IL-5, IL-13 and tumour necrosis factor-α (TNF-α) appearing in the bronchoalveolar lavage fluid 24 h after the antigen challenge. The combination index for inhibition of both inflammatory cells and cytokines was consistently <1 suggesting a synergistic interaction between MF and F. Intratracheal MF/F given 24 h after the aerosolized ovalbumin challenge reversed the reduction in FVC with statistically significant effects seen over a 24 h period after drug whereas MF and F alone reversed the antigen-induced reduction in FVC at selected times only. At 5 h after drug administration, when both MF and F were partially active, the combination index for MF/F was <1 suggesting a synergistic interaction between MF and F for reversal of the lung function. These results demonstrate that MF/F combination inhibits a variety of late-phase responses induced by allergen challenge and it is likely that MF/F will have a significant benefit in clinical asthma to suppress lung inflammation and improve lung function.
[Show abstract][Hide abstract] ABSTRACT: A strategy to overcome the side effect liabilities of oral PDE4 inhibitors has been to deliver the drugs by inhalation. In this report, we identify 1-[[5-(1(S)-aminoethly)-2-[8-methoxy-2-(triflurormethyl)-5-quinolinyl]-4-oxazolyl] carbonyl]-4(R)-[(cyclopropylcarbonyl)amino]-L-proline, ethyl ester xinafoate salt, (COMPOUND 1) as a potent and selective inhibitor of PDE4 with biological and pharmacokinetic properties suitable for delivery by the inhaled route. COMPOUND 1 potently inhibits human PDE4 (IC(50)=70pM) with little or no activity against other PDEs. It is highly potent against PDE4B and PDE4D which are important isoforms of PDE4 controlling inflammation and airway functions. In an allergen-challenged Brown Norway rat model of asthma, COMPOUND 1 inhibited the late phase influx of inflammatory cells and reductions in lung function following its administration by the intratracheal or nose-only routes of administration. Important differences were seen between intratracheal COMPOUND 1 and our previously published results with the oral PDE4 inhibitor roflumilast (Celly et al., 2005), as COMPOUND 1 rapidly (within 1h) reversed the decline in lung function when it was given therapeutically to rats already challenged with antigen. COMPOUND 1 was weakly active by the oral route which is a finding consistent with results showing this compound has poor oral bioavailability in animals. Positive interactions between COMPOUND 1 and albuterol, and COMPOUND 1 and mometasone furoate were seen on the improvement in lung functions in allergen-challenged rats. These results identify COMPOUND 1 as a potent and selective inhibitor of PDE4 with properties suitable for delivery by inhalation.
European journal of pharmacology 09/2010; 643(2-3):274-81. · 2.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Continuous isometric microfocal X-ray computed tomography (CT) scans were acquired from an AKR/J mouse, Brown-Norway rat, and Hartley guinea pig. The anatomy and volume of the paranasal sinus cavities were defined from 2-dimensional (2-D) and 3-dimensional (3-D) CT images. Realistic 3-D images were reconstructed and used to determine the anterior maxillary, posterior maxillary, and ethmoid sinus cavity airspace volumes (mouse: 0.6, 0.7, and 0.7 mm(3), rat: 8.6, 7.7, and 7.0 mm(3), guinea pig: 63.5, 46.6 mm(3), and no ethmoid cavity, respectively). The mouse paranasal sinus cavities are similar to the corresponding rat cavities, with a reduction in size, while the corresponding maxillary sinus cavities in the guinea pig are different in size, location, and architecture. Also, the ethmoid sinus cavity is connected by a common drainage pathway to the posterior maxillary sinus in mouse and rat while a similar ethmoid sinus was not present in the guinea pig. We conclude that paranasal sinus cavity airspace opacity (2-D) or volume (3-D) determined by micro-CT scanning may be used to conduct longitudinal studies on the patency of the maxillary sinus cavities of rodents. This represents a potentially useful endpoint for developing and testing drugs in a small animal model of sinusitis.
Canadian journal of veterinary research = Revue canadienne de recherche vétérinaire 07/2009; 73(3):205-11. · 0.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Manual total and differential leukocyte counting in bronchoalveolar lavage fluids (BALF) by visual microscopy is a standard
means of evaluating airway inflammation and the anti-inflammatory properties of therapeutics in various animal models of lung
disease. The manual cell counting method derives total leukocyte counts from BALF with a hemocytometer, and cell differentials
(mononuclear, neutrophil, eosinophil) are calculated from the percentage of each cell type taken from a count of at least
200 cells on a stained cytocentrifuge preparation of the BALF cells. These manual methods are time-consuming and have inherent
error–variability. The ADVIA 120 Hematology System is an automated analyzer designed to perform total and differential leukocyte
analysis of blood. With the light scattering, cell lysis resistance, and cytochemical staining data from a BALF sample processed
by the ADIVA, a BALF total leukocyte count and differential analysis is provided in approximately 30s. In order to correlate
automated BALF leukocyte counting by the ADVIA 120 Hematology System with manual counting, we developed a manual red blood
cell lysing and white blood cell staining technique for BALF cells similar to the process used by the ADVIA. Significant correlations
for BALF white blood cells were obtained for the manual (microscopic analysis) and the automated (ADVIA) methods. Comparison
of manual and automated cell counts also generates the same conclusions about anti-inflammatory drug efficacy. Both manual
and automated cell counting methods agree that 3mg/kg orally administered dexamethasone inhibited cigarette-smoke-induced
total BALF cell counts by ∼65% in mice and 42μg/kg fluticasone propionate delivered by nose-only inhalation inhibited allergen-induced
total BALF cells by 77% in rats. The use of the ADVIA to perform total and differential leukocyte counts in BALF will save
time spent manually counting cells and this instrument will standardize the analysis of white blood cells across the laboratories
currently using various manual counting preparations and procedures.