Anti-inflammatory and bronchodilator properties of KF19514, a phosphodiesterase 4 and 1 inhibitor

Pharmacological Profile of GPD-1116, an Inhibitor of Phosphodiesterase 4

We have previously reported that GPD-1116, an inhibitor of phosphodiesterase (PDE) 4, exhibits anti-inflammatory effects in a model of cigarette smoke-induced emphysema in senescence-accelerated P1 mice. In the present study, we further characterized the pharmacological profile of GPD-1116 in several experiments in vitro and in vivo. GPD-1116 and its metabolite GPD-1133 predominantly inhibited not only human PDE4, but also human PDE1 in vitro. Moreover, GPD-1116 was effective in several disease models in animals, including acute lung injury, chronic obstructive pulmonary disease (COPD), asthma and pulmonary hypertension; the effective doses of GPD-1116 were estimated to be 0.3-2 mg/kg in these models. With regard to undesirable effects known as class effects of PDE4 inhibitors, GPD-1116 showed suppression of gastric emptying in rats and induction of emesis in dogs, but showed no such suppression of rectal temperature in rats, and these side effects of GPD-1116 seemed to be less potent than those of roflumilast. These results suggested that GPD-1116 could be a promising therapeutic agent for the treatment of inflammatory pulmonary diseases. Furthermore, the inhibitory effects of GPD-1116 for PDE1 might be associated with its excellent pharmacological profile. However, the mechanisms through which PDE1 inhibition contributes to these effects should be determined in future studies.

Cyclic nucleotide-based therapeutics for chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) defines a group of chronic inflammatory disorders of the airways that are characterised by a progressive and largely irreversible decline in expiratory airflow. Drugs used to treat COPD through actions mediated by cyclic AMP (cAMP) are restricted to long-acting and short-acting β2-adrenoceptor agonists and, in a subset of patients with chronic bronchitis, a phosphodiesterase 4 inhibitor, roflumilast. These agents relax airway smooth muscle and suppress inflammation. At the molecular level, these effects in the airways are mediated by two cAMP effectors, cAMP-dependent protein kinase and exchange proteins activated by cAMP. The pharmacology of newer agents, acting through these systems, is discussed here with an emphasis on their potential to interact and increase therapeutic effectiveness.

Harnessing the clinical efficacy of phosphodiesterase 4 inhibitors in inflammatory lung diseases: dual-selective phosphodiesterase inhibitors and novel combination therapies

Phosphodiesterase (PDE) 4 inhibitors have been in development as a novel anti-inflammatory therapy for more than 20 years, with asthma and chronic obstructive pulmonary disease (COPD) being primary indications. Despite initial optimism, only one selective PDE4 inhibitor, roflumilast (Daxas (®)), has been approved for use in humans and available in Canada and the European Union in 2011 for the treatment of a specific population of patients with severe COPD. In many other cases, the development of PDE4 inhibitors of various structural classes has been discontinued due to lack of efficacy and/or dose-limiting adverse events. Indeed, for many of these compounds, it is likely that the maximum tolerated dose is either subtherapeutic or at the very bottom of the efficacy dose-response curve. Thus, a significant ongoing challenge that faces the pharmaceutical industry is to synthesize compounds with therapeutic ratios that are superior to roflumilast. Several strategies are being considered, but clinically effective compounds with an optimal pharmacophore have not, thus far, been reported. In this chapter, alternative means of harnessing the clinical efficacy of PDE4 inhibitors are described. These concepts are based on the assumption that additive or synergistic anti-inflammatory effects can be produced with inhibitors that target either two or more PDE families or with a PDE4 inhibitor in combination with other anti-inflammatory drugs such as a glucocorticoid.

Effects of KF19514, a phosphodiesterase 4 and 1 Inhibitor, on bronchial inflammation and remodeling in a murine model of chronic asthma

BACKGROUND

Phosphodiesterase 4 selective inhibitor may prevent airway inflammation and remodeling.

OBJECTIVE

The aim of this study was to investigate the effects of KF19514, a phosphodiesterase 4 and 1 dual inhibitor, on chronic airway inflammation and remodeling following chronic exposure to aerosolized antigen in mice.

METHODS

Ovalbumin (OVA) was administered intraperitoneally to BALB/c mice on days 0 and 14, and the mice were then exposed to aerosolized OVA daily for 4 weeks. Twenty-four hours following the final inhalation, bronchial responsiveness to acetylcholine was measured, and histologic examination and hydroxyproline content of the lung were evaluated.

RESULTS

Bronchial responsiveness to acetylcholine, number of inflammatory cells and eosinophils in the lamina propria, thickness of epithelial and subepithelial collagen layers, and hydroxyproline content of the lung increased following chronic exposure to OVA for 7 weeks. KF19514 significantly prevented all of these changes.

CONCLUSIONS

Phosphodiesterase 4 and 1 inhibitors such as KF19514 may help prevent bronchial hyperresponsiveness and chronic asthma-induced airway remodeling.

Differential effects of PDE4 inhibitors on cortical neurons and T-lymphocytes

Inhibitors of PDE4 (cAMP-specific phosphodiesterase) induce side effects, including nausea and emesis, that limit their therapeutic potential. We investigated the function of two catalytically active conformations of PDE4 (a low-affinity conformer detected by conventional cAMP hydrolytic activity and a high-affinity conformer detected by [(3)H]rolipram binding) in neuronal cells. We assessed enhancement of beta-adrenoceptor-mediated cAMP accumulation in cortical neurons in vitro by eleven PDE4 inhibitors with diverse biochemical profiles. The compounds tested have a wide inhibition range of PDE4 catalytic activity and [(3)H]rolipram binding. Inhibition potency for PDE4 catalytic activity and [(3)H]rolipram binding for each compound was different. Potency in augmentation of cAMP correlated significantly with the inhibitory effect on [(3)H]rolipram binding, but not with that against PDE4 catalytic activity. On the other hand, the inhibitory effect on proliferation of T-lymphocytes of the same PDE4 inhibitors correlated both with inhibition of PDE4 catalytic activity and with inhibition of [(3)H]rolipram binding. These findings indicate that the high affinity PDE4 conformer exists at a high level in cortical neurons and is important in the regulation of cAMP. Furthermore, the relative contributions of the two PDE4 conformers in cell function may cause different PDE4 inhibitor effects on cortical neurons and T-lymphocytes.

Correlation between emetic effect of phosphodiesterase 4 inhibitors and their occupation of the high-affinity rolipram binding site in Suncus murinus brain

We employed an ex vivo [(3)H]rolipram binding experiment to elucidate the mechanism of emetic activity of phosphodiesterase 4 inhibitors. In Suncus murinus (an insectivore used for evaluation of emesis), emetic potential as well as ability to occupy the high-affinity rolipram binding site in brain membrane fraction in vivo were determined for phosphodiesterase 4 inhibitors. In vitro, [(3)H]rolipram bound to the membrane fraction of S. murinus brain with high affinity and its value was comparable to that for rat brain (K(d)=3.6 nM and 3.5 nM, respectively). The test compounds included denbufylline, rolipram, piclamilast, CDP840 and KF19514, each of which possessed similar affinities for the rolipram binding sites in both S. murinus and rat brain. In S. murinus, these compounds induced emesis via intraperitoneal administration. Their ED(50) values were as follows: denbufylline (1.4 mg/kg), rolipram (0.16 mg/kg), piclamilast (1.8 mg/kg), CDP840 (20 mg/kg), and KF19514 (0.030 mg/kg). In addition, these compounds occupied the high-affinity rolipram binding site in vivo as detected by dose-dependent reduction in capacity of ex vivo [(3)H]rolipram binding in brain membrane fractions. A clear correlation was observed between dose required to induce emesis and that to occupy the high-affinity rolipram binding site for individual phosphodiesterase 4 inhibitors. We conclude that the emetic effect of phosphodiesterase 4 inhibitors is caused at least in part via binding to the high-affinity rolipram binding site in brain in vivo.

The therapeutic potential of PDE4 inhibitors

Phosphodiesterase enzymes are responsible for the inactivation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Phosphodiesterase 4 (PDE4) is a cAMP specific phosphodiesterase expressed in inflammatory cells such as eosinophils. Inhibition of PDE4 results in an elevation of cAMP in these cells, which in turn downregulates the inflammatory response. The anti-inflammatory effects of PDE4 inhibitors have been well documented both in vitro and in vivo in a variety of animal models. The potential use of PDE4 inhibitors as anti-inflammatory agents for the treatment of asthma and other inflammatory disorders has received considerable attention from the pharmaceutical industry, but to date, there are no selective PDE4 inhibitors on the market. Early PDE4 inhibitors, typified by rolipram, suffered from dose-limiting side effects, including nausea and emesis, which severely restricted their therapeutic utility. Second generation compounds, including CDP840 and SB207499 (Ariflo), have been identified with reduced side effect liability. Recent evidence suggests a correlation between side effects and the ability of compounds to bind at the so-called high affinity rolipram binding site (HPDE), whilst beneficial effects appear to correlate with binding at the catalytic site. A number of companies are actively pursuing compounds which exhibit improved affinity for the catalytic site and reduced affinity for the HPDE, in the expectation that this will provide compounds with an improved therapeutic index.

[Recent development of new drugs for the treatment of allergic diseases]

Due to the prevalence of allergic diseases such as bronchial asthma, allergic rhinoconjunctivitis and dermallergosis, efforts at the discovery of novel and effective medications for prevention and treatment of these conditions have been reinforced. Recently, it has been recognized that these allergic diseases are a chronic inflammatory disorder of the lower and upper airways and skin. In this article, we reviewed the recent development of the following new antiallergic therapies: anti-Th2 cytokine antibodies, decoy receptors, receptor antibodies, anti-IgE antibodies, anti-cell adhesion molecules antibodies, antisense oligonucleotides, keratinocyte modulators, inhibitors of phosphodiesterase 4, tachykinin receptor antagonists, and anti-histaminic drugs. Most of these new agents are aimed to inhibit various components of allergic inflammation. The future use of allergic disease therapies hold great promise and excitement.

The inhaled administration of KF19514, a phosphodiesterase 4 and 1 inhibitor, prevents antigen-induced lung inflammation in guinea pigs

We examined in this study the effect of KF19514, a phosphodiesterase 4 and 1 inhibitor, on antigen-induced lung inflammation by inhaled administration in guinea-pigs. It was previously reported that inhaled KF19514 prevented antigen-induced bronchoconstriction and platelet-activating factor (PAF)-induced lung inflammation. In fact, a variety of factors other than PAF are related to lung inflammation in real subjects with asthma. Guinea-pigs were actively sensitized by exposure to ovalbumin (OA). Fifteen to 20 days later, the guinea pigs were challenged by exposure to aerosols of five successively increasing concentrations of OA (0.01, 0.1, 0.5, 1 and 5 mg/ml). Bronchoalveolar lavages (BALs) were performed 24 h after the antigen challenge, and airway hyperresponsiveness to acetylcholine (ACh) was studied 24 h after the challenge by measuring lung resistance and dynamic compliance. Ovalbumin antigen challenge produced a marked and significant eosinophil accumulation in the BAL fluids and airway hyperresponsiveness to ACh 24 h after the challenge. Inhaled KF19514 (0.01-0.1%) inhibited the eosinophil accumulation significantly and dose-dependently but inhaled rolipram (0.01-0.1%) and aminophylline (0.1-1%) did not. In addition, the development of airway hyperresponsiveness was prevented by inhaled KF19514 (0.01%) but not by inhaled rolipram (0.01%) and aminophylline (0.1%). Based on these data, KF19514 was suggested to be a promising drug in the treatment of asthma by local administration to the lung.

Effect of aerosolized administration of KF19514, a phosphodiesterase 4 inhibitor, on bronchial hyperresponsiveness and airway inflammation induced by antigen inhalation in guinea-pigs

BACKGROUND

Although phosphodiesterase (PDE) 3 and 4 inhibitors have received much attention for the treatment of bronchial asthma, systemic adverse effects have also been reported.

OBJECTIVE

The purpose of this study was to investigate the effect of inhaled olprinone, a newly developed PDE3 inhibitor, and KF19514, a PDE1 and 4 inhibitor, on antigen-induced airway reactions in guinea-pigs.

METHODS

Fifteen minutes after inhalation of olprinone (0.1 or 1.0 mg/mL) and KF19514 (0.1 or 0.01 mg/mL), animals were given an antigen challenge. Bronchial hyper-responsiveness and bronchoalveolar lavage fluid cell analysis were performed 24 h after the antigen challenge.

RESULTS

Inhalation of olprinone and KF19514 caused a dose-related inhibition of antigen-induced bronchoconstriction. Antigen inhalation significantly increased bronchoconstrictor responses to methacholine, and airway accumulation of neutrophils and eosinophils, 24 h after the antigen challenge. These responses were dose-dependently prevented by KF19514, but not by olprinone.

CONCLUSION

The results indicate that inhaled PDE inhibitors might be useful for treatment of bronchial asthma.

Phosphodiesterase 4 inhibitors as novel anti-inflammatory agents

Preclinical and clinical studies of phosphodiesterase 4 inhibitors have shown that these agents may find utility in a wide range of inflammatory disorders, including asthma, chronic obstructive pulmonary disease, atopic dermatitis, rheumatoid arthritis, multiple sclerosis and various neurological disorders. The future of this class of drugs will depend upon the ability to demonstrate a reasonable safety margin against emesis and other typical phosphodieserase (PDE4) side effects, as well as in identification of the inflammatory disorder(s) most relevant to PDE4 inhibition.

Bronchoprotective effect of an intrabronchial administration of cilostazol powder and a nebulized PDE1 and PDE4 inhibitor KF19514 in guinea pigs

BACKGROUND

Both oral and intravenous inhibitors of cyclic nucleotide phosphodiesterase (PDE) 3 and PDE4 have been shown to have bronchodilator and/or pulmonary antiallergic effects but their adverse effects limit the clinical use. The purpose of the present study was to assess the bronchoprotective effect of intrabronchial administration of a selective PDE3 inhibitor, 6-[4-(1-cyclohexyl-1H-tetrazol-5-yl)butoxy]-3,4-dihydro-2(1H)-quin olinone (cilostazol), in dry power form which is proposed to be desirable rather than propellant-driven metered-dose inhalers.

METHODS

Effect of an intrabronchial administration of cilostazol powder on aerosolized histamine- and antigen-induced leukotriene-mediated bronchoconstriction were examined in anesthetized and artificially ventilated guinea pigs, in comparison with the effects of ultrasonically nebulized 5-phenyl-3-(3-pyridyl)methyl-3H-imidazo[4,5-c] [1,8] naphthyridin-4(5H)-one (KF19514), a selective PDE1/4 inhibitor.

RESULTS

Cilostazol powder and KF19514 solution inhibited histamine- and antigen-induced bronchoconstriction in a dose-dependent manner. When assessing the resulting ED50 values, the activity of cilostazol powder against antigen-induced broncho-constriction was weaker than its antagonism of histamine-induced bronchoconstriction (60.4 vs. 7.0 microg), while those of KF19514 were the opposite (0.40 vs. 2.81 microg/ml).

CONCLUSION

These results suggest that intrabronchially administered cilostazol powder has a bronchodilator effect, and ensure that PDE4 inhibitors have an antiallergic activity in addition to their bronchodilator effect.