Novel signal transduction modulators for the treatment of airway diseases

New phosphodiesterase-4 inhibitors present airways relaxant activity in a guinea pig acute asthma model

Asthma is a disease characterized by chronic inflammation and hyper responsiveness of airways. We aimed to assess the relaxant potential of phosphodiesterase-4 (PDE4) inhibitors N-sulfonilhidrazonic derivatives on non-asthmatic and asthmatic guinea pig trachea. Firstly, guinea pigs were sensitized and challenged with ovalbumin, and then morphological, and contractile changes were evaluated resulting from asthma, followed by evaluation of relaxant effect of derivatives on guinea pig trachea and the cAMP levels measurement by ELISA. It has been evidenced hypertrophy of airway smooth muscle, inflammatory infiltrate, and vascular abnormalities. Moreover, only sensitized tracheal rings were responsive to OVA. Contractile response to histamine, but not to carbachol, was greater in sensitized animals, however the relaxant response to aminophylline and isoprenaline were the same in non-asthmatics and asthmatics. N-sulfonilhidrazonic derivatives presented equipotent relaxant action independent of epithelium, with exception of LASSBio-1850 that presented a low efficacy (< 50%) and LASSBio-1847 with a 4-fold higher potency on asthmatics. LASSBio-1847 relaxant curve was impaired in the presence of propranolol and potentiated by isoprenaline in both groups. Furthermore, relaxation was potentiated 54- and 4-fold by forskolin in non-asthmatics and asthmatics, respectively. Likewise, LASSBio-1847 potentiated relaxant curve of aminophylline 147- and 4-fold in both groups. The PKA inhibitor H-89 impaired the relaxant potency of the derivative. Finally, LASSBio-1847 increased tracheal intracellular cAMP levels similarly to rolipram, selective PDE4 inhibitor, in both animals. LASSBio-1847 showed to be promising to relax guinea pig trachea from non-sensitized and sensitized guinea pigs by activation of β2-adrenergic receptors/AC/cAMP pathway.

Redox Regulation in Aging Lungs and Therapeutic Implications of Antioxidants in COPD

Mammals, including humans, are aerobic organisms with a mature respiratory system to intake oxygen as a vital source of cellular energy. Despite the essentiality of reactive oxygen species (ROS) as byproducts of aerobic metabolism for cellular homeostasis, excessive ROS contribute to the development of a wide spectrum of pathological conditions, including chronic lung diseases such as COPD. In particular, epithelial cells in the respiratory system are directly exposed to and challenged by exogenous ROS, including ozone and cigarette smoke, which results in detrimental oxidative stress in the lungs. In addition, the dysfunction of redox regulation due to cellular aging accelerates COPD pathogenesis, such as inflammation, protease anti-protease imbalance and cellular apoptosis. Therefore, various drugs targeting oxidative stress-associated pathways, such as thioredoxin and N-acetylcysteine, have been developed for COPD treatment to precisely regulate the redox system. In this review, we present the current understanding of the roles of redox regulation in the respiratory system and COPD pathogenesis. We address the insufficiency of current COPD treatment as antioxidants and discuss future directions in COPD therapeutics targeting oxidative stress while avoiding side effects such as tumorigenesis.

Progress in the mechanism and targeted drug therapy for COPD

Chronic obstructive pulmonary disease (COPD) is emphysema and/or chronic bronchitis characterised by long-term breathing problems and poor airflow. The prevalence of COPD has increased over the last decade and the drugs most commonly used to treat it, such as glucocorticoids and bronchodilators, have significant therapeutic effects; however, they also cause side effects, including infection and immunosuppression. Here we reviewed the pathogenesis and progression of COPD and elaborated on the effects and mechanisms of newly developed molecular targeted COPD therapeutic drugs. Among these new drugs, we focussed on thioredoxin (Trx). Trx effectively prevents the progression of COPD by regulating redox status and protease/anti-protease balance, blocking the NF-κB and MAPK signalling pathways, suppressing the activation and migration of inflammatory cells and the production of cytokines, inhibiting the synthesis and the activation of adhesion factors and growth factors, and controlling the cAMP-PKA and PI3K/Akt signalling pathways. The mechanism by which Trx affects COPD is different from glucocorticoid-based mechanisms which regulate the inflammatory reaction in association with suppressing immune responses. In addition, Trx also improves the insensitivity of COPD to steroids by inhibiting the production and internalisation of macrophage migration inhibitory factor (MIF). Taken together, these findings suggest that Trx may be the ideal drug for treating COPD.

The effects of neutralizing anti-murine interleukin-17A monoclonal antibody on ozone-induced inflammation and glucocorticoids insensitivity in a murine model of asthma

BACKGROUND AND OBJECTIVE

Exposure to ozone contributed to the worsening of inflammation and glucocorticoids insensitivity in OVA-challenged asthma. Interleukin-17A participates centrally in stages of the inflammatory response and glucocorticoids insensitivity. In this study, the effect of neutralizing anti-murine interleukin-17A monoclonal antibody (IL-17A mAb) on inflammation and glucocorticoids insensitivity in ozone-exposed and ovalbumin (OVA)-challenged mice was investigated.

METHODS

Mice were sensitized and challenged with OVA and then exposed to ozone. Dexamethasone (Dex) and IL-17A mAb were administrated in corresponding periods.

RESULTS

Compared with OVA-challenged mice, combination administration of ozone exposure and OVA challenge increased the recruitment of inflammatory cells in bronchoalveolar lavage fluid, enhanced the inflammation scores and levels of inflammatory cytokines and IL-17A mRNA, and caused the activation of p38 MAPK together with down regulation of glucocorticoids recepters (GR) in lung tissue. Monotherapy of IL-17A mAb partially attenuated lung inflammation in OVA-challenged and ozone-exposed mice, while the combination treatment of Dex and IL-17A mAb effectively reduced lung inflammation, inactivated p38 MAPK and up regulated GR in lung tissue.

CONCLUSIONS

Ozone exposure worsened OVA-challenged airway inflammation, activation of p38 MAPK and down regulation of GR in OVA-sensitized and -challenged mice, which was effectively counteracted by IL-17A mAb, and combination treatment of IL-17A mAb and Dex shows profound efficacy in inhibiting airway inflammation and improving glucocorticoids insensitivity synergistically.

Experimental and investigational phosphodiesterase inhibitors in development for asthma

INTRODUCTION

Severe, inadequately-controlled asthma remains a clinical challenge. For this reason, clinical trials and preclinical experimental studies on novel agents as an add-on therapies continue emerge. Phosphodiesterases (PDEs) are enzymes that regulate the function of immune cells by hydrolyzing cyclic guanosine monophosphate/cGMP and cyclic adenosine monophosphate/cAMP. PDEs are divided into subfamilies [PDE3, PDE4, PDE5 and PDE7] which are mainly found in the respiratory tract. Inhibitors of PDEs have already been approved for COPD and pulmonary hypertension.

AREAS COVERED

The role of PDE inhibitors in asthma treatment and the possible mechanism of action via their anti-inflammatory and/or bronchodilating effect are discussed.

EXPERT OPINION

Novel PDE inhibitors exhibiting fewer adverse events may have a role as add-on therapies in asthma treatment in the future. More clinical trials are necessary to prove their efficacy and evaluate their safety profile before approval by regulatory bodies is granted.

Syk Regulates Neutrophilic Airway Hyper-Responsiveness in a Chronic Mouse Model of Allergic Airways Inflammation

Background

Asthma is a chronic inflammatory disease characterized by airways hyper-responsiveness (AHR), reversible airway obstruction, and airway inflammation and remodeling. We previously showed that Syk modulates methacholine-induced airways contractility in naïve mice and in mice with allergic airways inflammation. We hypothesize that Syk plays a role in the pathogenesis of AHR; this was evaluated in a chronic 8-week mouse model of house dust mite (HDM)-induced allergic airways inflammation.

Methods

We used the Syk^flox/flox//rosa26CreER^T2 conditional Syk knock-out mice to assess the role of Syk prior to HDM exposure, and treated HDM-sensitized mice with the Syk inhibitor, GSK143, to evaluate its role in established allergic airways inflammation. Respiratory mechanics and methacholine (MCh)-responsiveness were assessed using the flexiVent^® system. Lungs underwent bronchoalveolar lavage to isolate inflammatory cells or were frozen for determination of gene expression in tissues.

Results

MCh-induced AHR was observed following HDM sensitization in the Syk-intact (Syk^flox/flox) and vehicle-treated BALB/c mice. MCh responsiveness was reduced to control levels in HDM-sensitized Syk^del/del mice and in BALB/c and Syk^flox/flox mice treated with GSK143. Both Syk^del/del and GSK143-treated mice mounted appropriate immune responses to HDM, with HDM-specific IgE levels that were comparable to Syk^flox/flox and vehicle-treated BALB/c mice. HDM-induced increases in bronchoalveolar lavage cell counts were attenuated in both Syk^del/del and GSK143-treated mice, due primarily to decreased neutrophil recruitment. Gene expression analysis of lung tissues revealed that HDM-induced expression of IL-17 and CXCL-1 was significantly attenuated in both Syk^del/del and GSK143-treated mice.

Conclusion

Syk inhibitors may play a role in the management of neutrophilic asthma.

Genome Expression Profiling-Based Identification and Administration Efficacy of Host-Directed Antimicrobial Drugs against Respiratory Infection by Nontypeable Haemophilus influenzae

Therapies that are safe, effective, and not vulnerable to developing resistance are highly desirable to counteract bacterial infections. Host-directed therapeutics is an antimicrobial approach alternative to conventional antibiotics based on perturbing host pathways subverted by pathogens during their life cycle by using host-directed drugs. In this study, we identified and evaluated the efficacy of a panel of host-directed drugs against respiratory infection by nontypeable Haemophilus influenzae (NTHi). NTHi is an opportunistic pathogen that is an important cause of exacerbation of chronic obstructive pulmonary disease (COPD). We screened for host genes differentially expressed upon infection by the clinical isolate NTHi375 by analyzing cell whole-genome expression profiling and identified a repertoire of host target candidates that were pharmacologically modulated. Based on the proposed relationship between NTHi intracellular location and persistence, we hypothesized that drugs perturbing host pathways used by NTHi to enter epithelial cells could have antimicrobial potential against NTHi infection. Interfering drugs were tested for their effects on bacterial and cellular viability, on NTHi-epithelial cell interplay, and on mouse pulmonary infection. Glucocorticoids and statins lacked in vitro and/or in vivo efficacy. Conversely, the sirtuin-1 activator resveratrol showed a bactericidal effect against NTHi, and the PDE4 inhibitor rolipram showed therapeutic efficacy by lowering NTHi375 counts intracellularly and in the lungs of infected mice. PDE4 inhibition is currently prescribed in COPD, and resveratrol is an attractive geroprotector for COPD treatment. Together, these results expand our knowledge of NTHi-triggered host subversion and frame the antimicrobial potential of rolipram and resveratrol against NTHi respiratory infection.

Lead Screening for Chronic Obstructive Pulmonary Disease of IKK2 Inhibited by Traditional Chinese Medicine

Chronic obstructive pulmonary disease (COPD) is a chronic obstructive lung disease and is frequently found in well-developed countries due to the issue of aging populations. Not all forms of medical treatment are unable to return a patient's limited pulmonary function back to normal and eventually they could require a lung transplant. At this time, COPD is the leading cause of death in the world. Studies surveying I-kappa-B-kinase beta (IKK2) are very relevant to the occurrence and deterioration of the condition COPD. The sinapic acid-4-O-sulfate, kaempferol, and alpha-terpineol were found to be IKK2 inhibitors and helped prevent COPD occurrence and worsening according to a screening of the traditional Chinese medicine (TCM) database. The protein-ligand interaction of these three compounds with regard to IKK2 was also done by molecular dynamics. The docking poses, hydrogen bond variation, and hydrophobic interactions found Asp103 and Lys106 are crucial to IKK2 binding areas for IKK2 inhibition. Finally, we found the three compounds that have an equally strong effect in terms of IKK2 binding proven by the TCM database and perhaps these may be an alternative treatment for COPD in the future.

Suppressive effects of fructus of Magnolia denudata on IL-4 and IL-13 expression in T cells

Magnolia species have been used for the treatment of allergic diseases in Asia as folk medicine; however, the cellular and molecular mechanisms of its anti-allergic effects have rarely been investigated. In this study, we demonstrated that a methanolic extract of the fructus of Magnolia denudata has suppressive effects on Th2 cytokine production such as IL-4 and IL-13, but not IFN-γ and IL-17, produced by both phorbol 12-myristate 13-acetate/ionomycin (PI)- and CD3/CD28-stimulated EL-4 T cells. Moreover, the mRNA expression of Th2 cytokines was significantly inhibited, and luciferase activity in cells transiently transfected with IL-4 or IL-13 promoter reporter plasmids was suppressed by M. denudata, indicating that M. denudata may regulate these expression at the transcriptional level. Western blot analysis for transcription factors involved in the cytokine gene expression indicated that the activation of c-Jun was significantly downregulated in the nucleus of cells, while the activations of nuclear factor of activated T cells, nuclear factor kappa B and c-Fos, were not affected. Furthermore, the mRNA expression and nuclear translocation of GATA-binding protein 3, a key transcriptional factor for Th2 commitment and Th2 cytokine expression, but not T-bet and RORγt, were dramatically downregulated by M. denudata. Treatment with M. denudata suppressed the phosphorylation of p38 mitogen-activated protein kinase; however, the PI-induced phosphorylation of extracellular signal-related kinase and c-Jun N-terminal kinase was unaffected. Taken together, our study indicated that M. denudata inhibited IL-4 and IL-13 expression, possibly through regulation of p38 mitogen-activated protein kinase phosphorylation and selective transcription factors, such as GATA-3 and c-Jun, in EL-4 T cells.

Simultaneous quantitation of IC87114, roflumilast and its active metabolite roflumilast N-oxide in plasma by LC-MS/MS: application for a pharmacokinetic study

A sensitive and reliable high-performance liquid chromatography-mass spectrometry (LC-MS/MS) was developed and validated for simultaneous quantification IC87114, roflumilast (RFM), and its active metabolite roflumilast N-oxide (RFN) using tolbutamide as an internal standard. The analytes were extracted by using liquid-liquid extraction and separated on a reverse phase C(18) column (50 mm × 3 mm i.d., 4.6 µ) using methanol: 2 mM ammonium acetate buffer, pH 4.0 as mobile phase at a flow rate 1 mL/min in gradient mode. Selective reaction monitoring was performed using the transitions m/z 398.3 > 145.9, 403.1 >186.9, 419.1 > 187.0 and 271.1 > 155.0 to quantify quantification IC87114, RFM, RFN and tolbutamide, respectively. The method was validated over the concentration range of 0.1-60 ng.mL(-1) for RFM and RFN and 6 to 2980 ng.mL(-1) for IC87114. Intra- and inter-day accuracy and precision of validated method were within the acceptable limits of <15% at all concentrations. Coefficients of correlation (r(2) ) for the calibration curves were >0.99 for all analytes. The quantitation method was successfully applied for simultaneous estimation of IC87114, RFM and RFN in a pharmacokinetic drug-drug interaction study in Wistar rats.

An engineered disulfide bond reversibly traps the IgE-Fc3-4 in a closed, nonreceptor binding conformation

IgE antibodies interact with the high affinity IgE Fc receptor, FcεRI, and activate inflammatory pathways associated with the allergic response. The IgE-Fc region, comprising the C-terminal domains of the IgE heavy chain, binds FcεRI and can adopt different conformations ranging from a closed form incompatible with receptor binding to an open, receptor-bound state. A number of intermediate states are also observed in different IgE-Fc crystal forms. To further explore this apparent IgE-Fc conformational flexibility and to potentially trap a closed, inactive state, we generated a series of disulfide bond mutants. Here we describe the structure and biochemical properties of an IgE-Fc mutant that is trapped in the closed, non-receptor binding state via an engineered disulfide at residue 335 (Cys-335). Reduction of the disulfide at Cys-335 restores the ability of IgE-Fc to bind to its high affinity receptor, FcεRIα. The structure of the Cys-335 mutant shows that its conformation is within the range of previously observed, closed form IgE-Fc structures and that it retains the hydrophobic pocket found in the hinge region of the closed conformation. Locking the IgE-Fc into the closed state with the Cys-335 mutation does not affect binding of two other IgE-Fc ligands, omalizumab and DARPin E2_79, demonstrating selective blocking of the high affinity receptor binding.

Host cell kinases, α5 and β1 integrins, and Rac1 signalling on the microtubule cytoskeleton are important for non-typable Haemophilus influenzae invasion of respiratory epithelial cells

Non-typable Haemophilus influenzae (NTHi) is a common commensal of the human nasopharynx, but causes opportunistic infection when the respiratory tract is compromised by infection or disease. The ability of NTHi to invade epithelial cells has been described, but the underlying molecular mechanisms are poorly characterized. We previously determined that NTHi promotes phosphorylation of the serine-threonine kinase Akt in A549 human lung epithelial cells, and that Akt phosphorylation and NTHi cell invasion are prevented by inhibition of phosphoinositide 3-kinase (PI3K). Because PI3K-Akt signalling is associated with several host cell networks, the purpose of the current study was to identify eukaryotic molecules important for NTHi epithelial invasion. We found that inhibition of Akt activity reduced NTHi internalization; differently, bacterial entry was increased by phospholipase Cγ1 inhibition but was not affected by protein kinase inhibition. We also found that α5 and β1 integrins, and the tyrosine kinases focal adhesion kinase and Src, are important for NTHi A549 cell invasion. NTHi internalization was shown to be favoured by activation of Rac1 guanosine triphosphatase (GTPase), together with the guanine nucleotide exchange factor Vav2 and the effector Pak1. Also, Pak1 might be associated with inactivation of the microtubule destabilizing agent Op18/stathmin, to facilitate microtubule polymerization and NTHi entry. Conversely, inhibition of RhoA GTPase and its effector ROCK increased the number of internalized bacteria. Src and Rac1 were found to be important for NTHi-triggered Akt phosphorylation. An increase in host cyclic AMP reduced bacterial entry, which was linked to protein kinase A. These findings suggest that NTHi finely manipulates host signalling molecules to invade respiratory epithelial cells.

The high affinity IgE receptor (FcεRI) expression and function in airway smooth muscle

The airway smooth muscle (ASM) is no longer considered as merely a contractile apparatus and passive recipient of growth factors, neurotransmitters and inflammatory mediators signal but a critical player in the perpetuation and modulation of airway inflammation and remodeling. In recent years, a molecular link between ASM and IgE has been established through Fc epsilon receptors (FcεRs) in modulating the phenotype and function of these cells. Particularly, the expression of high affinity IgE receptor (FcεRI) has been noted in primary human ASM cells in vitro and in vivo within bronchial biopsies of allergic asthmatic subjects. The activation of FcεRI on ASM cells suggests a critical yet almost completely ignored network which may modulate ASM cell function in allergic asthma. This review is intended to provide a historical perspective of IgE effects on ASM and highlights the recent updates in the expression and function of FcεRI, and to present future perspectives of activation of this pathway in ASM cells.

Treatment of allergic asthma: modulation of Th2 cells and their responses

Atopic asthma is a chronic inflammatory pulmonary disease characterised by recurrent episodes of wheezy, laboured breathing with an underlying Th2 cell-mediated inflammatory response in the airways. It is currently treated and, more or less, controlled depending on severity, with bronchodilators e.g. long-acting beta agonists and long-acting muscarinic antagonists or anti-inflammatory drugs such as corticosteroids (inhaled or oral), leukotriene modifiers, theophyline and anti-IgE therapy. Unfortunately, none of these treatments are curative and some asthmatic patients do not respond to intense anti-inflammatory therapies. Additionally, the use of long-term oral steroids has many undesired side effects. For this reason, novel and more effective drugs are needed. In this review, we focus on the CD4+ Th2 cells and their products as targets for the development of new drugs to add to the current armamentarium as adjuncts or as potential stand-alone treatments for allergic asthma. We argue that in early disease, the reduction or elimination of allergen-specific Th2 cells will reduce the consequences of repeated allergic inflammatory responses such as lung remodelling without causing generalised immunosuppression.

Aminopyridinecarboxamide-based inhaled IKK-2 inhibitors for asthma and COPD: Structure-activity relationship

Installation of sites for metabolism in the lead compound PHA-767408 was the key focus of the IKK-2 inhaled program. This paper reports our efforts to identify a novel series of aminopyridinecarboxamide-based IKK-2 inhibitors, which display low nanomolar potency against IKK-2 with long duration of action (DOA), and metabolically labile to phase I and/or phase II metabolizing enzymes with potential capability for multiple routes of clearance. Several compounds have demonstrated their potential usefulness in the treatment of asthma and chronic obstructive pulmonary disease (COPD).

Dual effect of neutrophils on pIgR/secretory component in human bronchial epithelial cells: role of TGF-beta

Neutrophils have a dual affect on epithelial pIgR/SC, the critical receptor for transcellular routing of mucosal IgA, but mechanisms of pIgR/SC upregulation remain elusive. Requirements of cytokine, redox, and signalling pathways for pIgR/SC production were assessed in human bronchial epithelial (Calu-3) cells cocultured with increasing numbers of blood neutrophils. Increased SC production was observed after incubation for 48 hrs with intermediate neutrophil numbers (1.25 to 2.5 × 10⁶), was favoured by the elastase inhibitor SLPI, and correlated with increased TGF-β production. Exogenous TGF-β stimulated SC production with a maximal effect at 48 hrs and both TGF-β- and neutrophil-driven SC upregulation were dependent on redox balance and p38 MAP-kinase activation. This paper shows that activated neutrophils could upregulate epithelial pIgR/SC production through TGF-β-mediated activation of a redox-sensitive and p38 MAPK-dependent pathway. An imbalance between the two neutrophil-driven opposite mechanisms (SC upregulation and SC degradation) could lead to downregulation of pIgR/SC, as observed in severe COPD.

Immunomodulators in asthma therapy

New developments in the field of allergy and immunology have yielded a variety of novel therapeutic approaches in recent years, and more agents are at the clinical trial stage. Among the therapeutic approaches discussed in this review are Toll-like receptor agonists, immunostimulatory oligodeoxynucleotides, orally and parenterally administered cytokine blockers, and specific cytokine receptor antagonists. Transcription factor modulators targeting syk kinase, peroxisome proliferator-activated receptor-gamma, and nuclear factor-kappaB are also being evaluated in the treatment of asthma. The anti-IgE monoclonal antibody omalizumab has established effectiveness in patients with allergic asthma, but the criteria for selecting patients who are most likely to benefit from it are less clear. This review summarizes data from human clinical trials with immunomodulators to discuss the rationale for their use, their efficacy, and adverse events associated with them.

A randomized study comparing the effect of loratadine added to montelukast with montelukast, loratadine, and beclomethasone monotherapies in patients with chronic asthma

BACKGROUND

Loratadine added to montelukast has been suggested to improve endpoints of asthma.

OBJECTIVE

This study investigated the additive effects of concomitant montelukast and loratadine when compared with montelukast, loratadine, and inhaled beclomethasone monotherapies in asthma. Methods. Patients (N = 406) were 15 to 65 years of age with a forced expiratory volume in 1 second (FEV(1))-predicted of 50% to 85%, FEV(1) reversibility > or = 15%, and a minimal level of daytime symptoms and beta -agonist use. This three-part 2X2 crossover-study consisted of two double-blind 6-week treatment periods where patients were administered once daily oral montelukast 10 mg, loratadine 10 mg, montelukast 10 mg + loratadine 10 mg, or twice daily inhaled beclomethasone 200 mu g. A subsequent 48-week extension study compared montelukast + loratadine with beclomethasone. The primary endpoint was the percentage change from baseline in FEV(1).

RESULTS

Over 6 weeks of double-blind treatment, significant improvements (p < 0.05) in the primary endpoint of FEV(1) were seen for montelukast + loratadine versus loratadine (least-square mean percentage-point difference of 5.8%), beclomethasone versus montelukast + loratadine (2.35%), montelukast versus loratadine (5.94%), and beclomethasone versus montelukast (4.65%); a numerical improvement (p = 0.054) was seen for montelukast + loratadine versus montelukast (1.60%). Significant improvements for montelukast + loratadine versus montelukast were seen in some secondary endpoints (evening peak expiratory flow, nocturnal asthma symptom score, nocturnal awakenings, and asthma-specific quality of life) but not others. Significant improvements in most endpoints except daytime asthma symptoms score were seen for montelukast + loratadine versus loratadine. In the extension study, both montelukast + loratadine and beclomethasone improved several endpoints. All treatments were generally comparable in the percentage of patients with clinical and laboratory adverse experiences.

CONCLUSION

In this study, the addition of loratadine to montelukast produced a small numerical, but not statistically significant, improvement in FEV(1) and, in general, no consistent improvement in other asthma endpoints. No improvement of montelukast + loratadine versus beclomethasone was seen in any endpoint.

Novel tight-binding inhibitory factor-kappaB kinase (IKK-2) inhibitors demonstrate target-specific anti-inflammatory activities in cellular assays and following oral and local delivery in an in vivo model of airway inflammation

Nuclear factor-kappaB (NF-kappaB) is one of the major families of transcription factors activated during the inflammatory response in asthma and chronic obstructive pulmonary disease. Inhibitory factor-kappaB kinase 2 (IKK-2) has been shown to play a pivotal role in cytokine-induced NF-kappaB activation in airway epithelium and in disease-relevant cells. Nevertheless, the potential toxicity of specific IKK-2 inhibitors may be unacceptable for oral delivery in chronic obstructive pulmonary disease. Therefore, local delivery to the lungs is an attractive alternative that warrants further exploration. Here, we describe potent and selective small-molecule IKK-2 inhibitors [8-(5-chloro-2-(4-methylpiperazin-1-yl)isonicotinamido)-1-(4-fluorophenyl)-4,5-dihydro-1H-benzo[g]indazole-3-carboxamide (PHA-408) and 8-(2-(3,4-bis(hydroxymethyl)-3,4-dimethylpyrrolidin-1-yl)-5-chloroisonicotinamido)-1-(4-fluorophenyl)-4,5-dihydro-1H-benzo-[g]indazole-3-carboxamide (PF-184)] that are competitive for ATP have slow off-rates from IKK-2 and display broad in vitro anti-inflammatory activities resulting from NF-kappaB pathway inhibition. Notably, PF-184 has been designed to have high systemic clearance, which limits systemic exposure and maximizes the effects locally in the airways. We used an inhaled lipopolysaccharide-induced rat model of neutrophilia to address whether inhibiting NF-kappaB activation locally within the airways would show anti-inflammatory effects in the absence of systemic exposure. PHA-408, a low-clearance compound previously shown to be efficacious orally in a rodent model of arthritis, dose-dependently attenuated inhaled lipopolysaccharide-induced cell infiltration and cytokine production. Interestingly, PF-184 produced comparable dose-dependent anti-inflammatory activity by intratracheal administration and was as efficacious as intratracheally administered fluticasone propionate (fluticasone). Together, these results support the potential therapeutic utility of IKK-2 inhibition in inflammatory pulmonary diseases and demonstrate anti-inflammatory efficacy of an inhaled IKK-2 inhibitor in a rat airway model of neutrophilia.

Discovery of (S)-N-[2-[1-(3-ethoxy-4-methoxyphenyl)-2-methanesulfonylethyl]-1,3-dioxo-2,3-dihydro-1H-isoindol-4-yl] acetamide (apremilast), a potent and orally active phosphodiesterase 4 and tumor necrosis factor-alpha inhibitor

In this communication, we report the discovery of 1S (apremilast), a novel potent and orally active phosphodiesterase 4 (PDE4) and tumor necrosis factor-alpha inhibitor. The optimization of previously reported 3-(1,3-dioxo-1,3-dihydroisoindol-2-yl)-3-(3,4-dimethoxyphenyl)propionic acid PDE4 inhibitors led to this series of sulfone analogues. Evaluation of the structure-activity relationship of substitutions on the phthalimide group led to the discovery of an acetylamino analogue 1S, which is currently in clinical trials.

The cytokine network in asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease (COPD) are very common inflammatory diseases of the airways. They both cause airway narrowing and are increasing in incidence throughout the world, imposing enormous burdens on health care. Cytokines play a key role in orchestrating the chronic inflammation and structural changes of the respiratory tract in both asthma and COPD and have become important targets for the development of new therapeutic strategies in these diseases.

Randomized, placebo-controlled study of a selective PDE4 inhibitor in the treatment of asthma

BACKGROUND

Phosphodiesterase-4 (PDE4) inhibitors have potential utility as a new therapeutic approach to improving symptoms and pulmonary function in asthma and COPD. This study evaluated the efficacy and safety of MK-0359, a selective and potent oral PDE4 inhibitor, in chronic asthma.

METHODS

Adults (N=88) with > or =1 year asthma history and an FEV(1) 50-80% predicted were randomized to double-blind treatment with MK-0359 (15mg/day) or placebo for 14 days, then crossed-over to the other treatment for 14 days. The primary endpoint was the change from baseline in FEV(1) at the end of each 2-week treatment period. Secondary and other endpoints included the changes from baseline in Daytime asthma symptom score, Nighttime asthma symptom score, Total daily beta-agonist use (puffs/day), AM and PM peak expiratory flow (PEF) and overall asthma-specific quality-of-life. Safety and tolerability were assessed by clinical adverse experiences.

RESULTS

MK-0359 significantly improved the primary endpoint (versus placebo): the least-squares mean difference in change from baseline in FEV(1) (L) was 0.09L (95% CI 0.01, 0.18). Endpoints of Daytime asthma symptom score, Nighttime asthma symptom score, Total daily beta-agonist use, AM PEF, PM PEF, and quality-of-life were also significantly improved. Nineteen patients (24.1%) on MK-0359 and 8 patients (10.4%) on placebo reported gastrointestinal clinical adverse experiences. Serious gastrointestinal clinical adverse experiences were reported in 3 patients while receiving MK-0359.

CONCLUSION

Over a 14-day treatment period, the oral PDE4 inhibitor MK-0359 improved lower airway function, symptoms and rescue medication use in chronic asthma, although at the expense of gastrointestinal adverse experiences. (Clinical trial registry number: NCT00482898.).

Inhibition of lipopolysaccharide-stimulated chronic obstructive pulmonary disease macrophage inflammatory gene expression by dexamethasone and the p38 mitogen-activated protein kinase inhibitor N-cyano-N'-(2-{[8-(2,6-difluorophenyl)-4-(4-fluoro-2-methylphenyl)-7-oxo-7,8-dihydropyrido[2,3-d] pyrimidin-2-yl]amino}ethyl)guanidine (SB706504)

p38 mitogen-activated protein kinase (MAPK) signaling is known to be increased in chronic obstructive pulmonary disease (COPD) macrophages. We have studied the effects of the p38 MAPK inhibitor N-cyano-N'-(2-{[8-(2,6-difluorophenyl)-4-(4-fluoro-2-methylphenyl)-7-oxo-7,8-dihydropyrido[2,3-d]-pyrimidin-2-yl]amino}ethyl)guanidine (SB706504) and dexamethasone on COPD macrophage inflammatory gene expression and protein secretion. We also studied the effects of combined SB706504 and dexamethasone treatment. Lipopolysaccharide (LPS)-stimulated monocyte derived macrophages (MDMs) and alveolar macrophages (AMs) were cultured with dexamethasone and/or SB706504. MDMs were used for gene array and protein studies, whereas tumor necrosis factor (TNF) alpha protein production was measured from AMs. SB706504 caused transcriptional inhibition of a range of cytokines and chemokines in COPD MDMs. The use of SB706504 combined with dexamethasone caused greater suppression of gene expression (-8.90) compared with SB706504 alone (-2.04) or dexamethasone (-3.39). Twenty-three genes were insensitive to the effects of both drugs, including interleukin (IL)-1beta, IL-18, and chemokine (CC motif) ligand (CCL) 5. In addition, the chromosome 4 chemokine cluster members, CXCL1, CXCL2, CXCL3, and CXCL8, were all glucocorticoid-resistant. SB706504 significantly inhibited LPS-stimulated TNFalpha production from COPD and smoker AMs, with near-maximal suppression caused by combination treatment with dexamethasone. We conclude that SB706504 targets a subset of inflammatory macrophage genes and when used with dexamethasone causes effective suppression of these genes. SB706504 and dexamethasone had no effect on the transcription of a subset of LPS-regulated genes, including IL-1beta, IL-18, and CCL5, which are all known to be involved in the pathogenesis of COPD.

PDE4 inhibitors: current status

Phosphodiesterase4 inhibitors are currently under development for the treatment of respiratory diseases including asthma and chronic obstructive pulmonary disease. The rationale for the development of this drug class stems from our understanding of the role of PDE4 in suppressing the function of a range of inflammatory and resident cells thought to contribute toward the pathogenesis of these diseases. Similarly, numerous preclinical in vivo studies have shown that PDE4 inhibitors suppress characteristic features of these diseases, namely, cell recruitment, activation of inflammatory cells and physiological changes in lung function in response to a range of insults to the airways. These potentially beneficial actions of PDE4 inhibitors have been successfully translated in phase II and III clinical trials with roflumilast and cilomilast. However, dose limiting side effects of nausea, diarrhoea and headache have tempered the enthusiasm of this drug class for the treatment of these respiratory diseases. A number of strategies are currently being pursued in attempts to improve clinical efficacy and reduce side effects, including delivery via the inhaled route, and/or development of non-emetic PDE4 inhibitors and mixed PDE inhibitors.

Montelukast inhibits tumour necrosis factor-alpha-mediated interleukin-8 expression through inhibition of nuclear factor-kappaB p65-associated histone acetyltransferase activity

BACKGROUND

Montelukast is a potent cysteinyl leukotriene-1 receptor antagonist possessing some anti-inflammatory effects although the molecular mechanism of these anti-inflammatory effects is unknown. In this study, we aimed to investigate the effect of montelukast on nuclear factor (NF)-kappaB-associated histone acetylation activity in phorbol myristate acetate (PMA)-differentiated U937 cells.

METHODS

We examined the inhibitory effects of montelukast on TNF-alpha-induced IL-8 production in PMA-differentiated U-937 cells. U-937 cells were exposed to PMA (50 ng/mL) for 48 h to allow differentiation to macrophages. Macrophages were then exposed to TNF-alpha (10 ng/mL) in the presence or absence of montelukast (0.01-10 microm) for 24 h. After this time, the concentration of IL-8 in the culture supernatant was measured by sandwich-type ELISA kit. The effect of signalling pathways on TNF-alpha-induced IL-8 release was examined pharmacologically using selective NF-kappaB/IKK2 (AS602868, 3 microm), (PD98059, 10 microm) and p38 mitogen activated protein kinase (MAPK) (SB203580, 1 microm) inhibitors. NF-kappaB DNA binding activity was measured by a DNA-binding ELISA-based assay. NF-kappaB-p65-associated histone acetyltransferase (HAT) activity was measured by immunoprecipitation linked to commercial fluorescent HAT.

RESULTS

TNF-alpha-induced IL-8 release was suppressed by an NF-kappaB inhibitor but not by MEK or p38 MAPK inhibitors. Montelukast induced a concentration-dependent inhibition of TNF-alpha-induced IL-8 release and mRNA expression that reached a plateau at 0.1 microm without affecting cell viability. Montelukast did not affect NF-kappaB p65 activation as measured by DNA binding but suppressed NF-kappaB p65-associated HAT activity.

CONCLUSION

Montelukast inhibits TNF-alpha-stimulated IL-8 expression through changes in NF-kappaB p65-associated HAT activity. Drugs targeting these enzymes may enhance the anti-inflammatory actions of montelukast.

Equine recurrent airway obstruction and insect bite hypersensitivity: understanding the diseases and uncovering possible new therapeutic approaches

Recurrent airway obstruction (RAO) and insect bite hypersensitivity (IBH) are allergic conditions that are commonly encountered in the horse. Whilst complete allergen avoidance is an effective management strategy for both diseases, this may not be achievable in all cases and treatment options are therefore required. The inflammatory response is the main therapeutic target for glucocorticoids given to horses with RAO and severe cases of IBH, whilst the bronchodilators used in RAO primarily target airway smooth muscle. Such drugs are effective in most but not all individuals and there may be unwanted adverse effects. This article will review how knowledge of drug action and the pathogenesis of RAO and IBH can be utilised to identify potential targets for novel therapeutic agents that, in the longer term, may be safer and/or more effective in managing the allergic horse.

Syk inhibitors as treatment for allergic rhinitis

Allergic rhinitis is characterized by a hypersensitive immune response in the upper airways to seasonal or perennial allergens leading to episodes of sneezing, itching, runny nose and nasal congestion. These symptoms are mainly the manifestations of a large number of mediators released by mast cells and basophils localized in the nasal mucosa, following their activation via allergen-specific immunoglobulin E (IgE) receptors. Current medications antagonize the action of distinct mediators such as histamine and leukotrienes for symptom relief, or block the production of pro-inflammatory cytokines to suppress allergic inflammation. Notably, rather than neutralizing individual mediators, Syk kinase inhibitors can block the allergen-induced release of all mast cell mediators and the production of most eicosanoids and cytokines. Thus, Syk kinase represents an attractive therapeutic target for acute and chronic allergic inflammation. Syk kinase inhibitors are now entering clinical trials. Using cell-based structure-activity relationships with primary human mast cells, a series of 2,4-diaminopyrimidine Syk kinase inhibitors was developed. One of these compounds, referred to as R112, exhibited suitable characteristics for intranasal delivery and was tested for safety and efficacy in allergic rhinitis patients. In a park environment, R112 showed remarkable amelioration of acute allergic rhinitis symptoms with rapid onset of action. These results demonstrate the clinical significance of inhibiting Syk in allergic upper airway disorders.

Anaplasma phagocytophilum specifically induces tyrosine phosphorylation of ROCK1 during infection

Anaplasma phagocytophilum, an obligate intracellular pathogen that persists within polymorphonuclear leucocytes, is the second most common tick-borne agent in North America. We now show that infection of a promyelocytic cell line and neutrophils with A. phagocytophilum results in pathogen-specific tyrosine phosphorylation of ROCK1. Phosphorylation is associated with PSGL-1 and Syk, because PSGL-1 blocking antibodies and siRNA targeting Syk interfere with ROCK1 phosphorylation in A. phagocytophilum-infected cells. Knockdown of either Syk or ROCK1 also markedly impaired A. phagocytophilum infection. These data demonstrate a role for A. phagocytophilum-mediated ROCK1 phosphorylation in infection, and suggests that inhibiting this pathway may lead to new, non-antibiotic strategies to treat human granulocytic anaplasmosis.

Regulation of Th2 Cytokine Genes by p38 MAPK-Mediated Phosphorylation of GATA-3

GATA-3 plays a critical role in allergic diseases by regulating the release of cytokines from Th2 lymphocytes. However, the molecular mechanisms involved in the regulation of GATA-3 in human T lymphocytes are not yet understood. Using small interfering RNA to knock down GATA-3, we have demonstrated its critical role in regulating IL-4, IL-5, and IL-13 release from a human T cell line. Specific stimulation of T lymphocytes by costimulation of CD3 and CD28 to mimic activation by APCs induces translocation of GATA-3 from the cytoplasm to the nucleus, with binding to the promoter region of Th2 cytokine genes, as determined by chromatin immunoprecipitation. GATA-3 nuclear translocation is dependent on its phosphorylation on serine residues by p38 MAPK, which facilitates interaction with the nuclear transporter protein importin-alpha. This provides a means whereby allergen exposure leads to the expression of Th2 cytokines, and this novel mechanism may provide new approaches to treating allergic diseases.

Differential regulation of TNFalpha and GM-CSF induced activation of P38 MAPK in neutrophils and eosinophils

P38 MAPK is a central mediator in cytokine signalling in human leukocytes. P38 MAPK is activated by phosphorylation of a conserved Thr180-X-Tyr182 motif by dual phosphorylation via the upstream kinases MKK3 and MKK6. Alternatively, P38 MAPK can be activated via autophosphorylation when associated with TAB1. In this study P38 MAPK phosphorylation and activation (measured via phosphorylation of P38 MAPK downstream target MK2) were investigated upon engagement of the GM-CSF- and TNFalpha-receptors expressed on both eosinophils and neutrophils. The MKK3/MKK6 pathway mediated neutrophil P38 MAPK activation after stimulation with TNFalpha (100U/ml) or GM-CSF (10(-10)M). Under these conditions the activation but not phosphorylation of P38 MAPK could be inhibited by SB203580 (10(-5)M or 10(-6)M). In eosinophils SB203580 (10(-6)M) inhibited both the phosphorylation and activation of P38 MAPK after stimulation with several doses of TNFalpha (10-10000 U/ml) or GM-CSF (10(-11) to 10(-9)M), indicating that P38 MAPK activation is mediated via autophosphorylation in eosinophils. This hypothesis was supported by the finding that in marked contrast to neutrophils, MKK3/MKK6 did not show enhanced phosphorylation in eosinophils after cytokine stimulation, but were constitutively phosphorylated. Therefore, the involvement of TAB1 was investigated with regard to this cytokine-induced autophosphorylation. Co-immunoprecipitation experiments showed that TAB1 was constitutively associated with P38 MAPK in eosinophils and neutrophils and that cytokine-induced autophosphorylated P38 MAPK was co-precipitated with TAB1. These findings are consistent with the hypothesis that cytokine-induced autophosphorylation of P38 MAPK in primary granulocytes depends on the interaction with TAB1.

New therapies for asthma

Asthma is an increasing global health problem, and many patients continue to suffer from chronic symptoms. However, current therapy with inhaled corticosteroids and a long-acting inhaled beta(2)-agonist is highly effective, safe and inexpensive. This poses a major hurdle to the development of new therapies that aim to improve on current treatments. An important unmet need is the treatment of severe asthma, which has different characteristics to mild and moderate asthma and is more similar to chronic obstructive pulmonary disease. Several new treatments are now under development but many of them are too specific, targeting a single receptor, enzyme or mediator, and are unlikely to have a major clinical impact. Another unmet need is the development of an effective oral therapy for mild and moderate asthma, but it is unlikely that such a treatment will be discovered because side effects might be a major problem. Prospects for a cure are currently remote but might arise from the development of vaccines that target the aberrant immune function in asthma.