Roflumilast: the new orally active, selective phophodiesterase-4 inhibitor, for the treatment of COPD

Opportunities and perspectives of small molecular phosphodiesterase inhibitors in neurodegenerative diseases

Phosphodiesterase (PDE) is a superfamily of enzymes that are responsible for the hydrolysis of two second messengers: cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). PDE inhibition promotes the gene transcription by activating cAMP-response element binding protein (CREB), initiating gene transcription of brain-derived neurotrophic factor (BDNF). The procedure exerts neuroprotective profile, and motor and cognitive improving efficacy. From this point of view, PDE inhibition will provide a promising therapeutic strategy for treating neurodegenerative disorders. Herein, we summarized the PDE inhibitors that have entered the clinical trials or been discovered in recent five years. Well-designed clinical or preclinical investigations have confirmed the effectiveness of PDE inhibitors, such as decreasing Aβ oligomerization and tau phosphorylation, alleviating neuro-inflammation and oxidative stress, modulating neuronal plasticity and improving long-term cognitive impairment.

Phosphodiesterase-4 Inhibition in Parkinson's Disease: Molecular Insights and Therapeutic Potential

Clinicians and researchers are exploring safer and novel treatment strategies for treating the ever-prevalent Parkinson's disease (PD) across the globe. Several therapeutic strategies are used clinically for PD, including dopamine replacement therapy, DA agonists, MAO-B blockers, COMT blockers, and anticholinergics. Surgical interventions such as pallidotomy, particularly deep brain stimulation (DBS), are also employed. However, they only provide temporal and symptomatic relief. Cyclic adenosine monophosphate (cAMP) is one of the secondary messengers involved in dopaminergic neurotransmission. Phosphodiesterase (PDE) regulates cAMP and cGMP intracellular levels. PDE enzymes are subdivided into families and subtypes which are expressed throughout the human body. PDE4 isoenzyme- PDE4B subtype is overexpressed in the substantia nigra of the brain. Various studies have implicated multiple cAMP-mediated signaling cascades in PD, and PDE4 is a common link that can emerge as a neuroprotective and/or disease-modifying target. Furthermore, a mechanistic understanding of the PDE4 subtypes has provided perceptivity into the molecular mechanisms underlying the adverse effects of phosphodiesterase-4 inhibitors (PDE4Is). The repositioning and development of efficacious PDE4Is for PD have gained much attention. This review critically assesses the existing literature on PDE4 and its expression. Specifically, this review provides insights into the interrelated neurological cAMP-mediated signaling cascades involving PDE4s and the potential role of PDE4Is in PD. In addition, we discuss existing challenges and possible strategies for overcoming them.

A highly efficient metal-free selective 1,4-addition of difluoroenoxysilanes to chromones

A highly efficient metal-free selective 1,4-addition reaction of difluoroenoxysilanes to chromones was developed using the low-cost and readily available HOTf as the catalyst, which is a facile and straightforward method to access valuable C2-difluoroalkylated chroman-4-one derivatives. Interestingly, the products could be readily converted to the difluorinated bioisostere of the natural product (S)-2,6-dimethylchroman-4-one and a difluorinated benzo-seven-membered heterocycle via the Schmidt rearrangement reaction. In addition, the in vitro anti-proliferative activities of these synthesized derivatives against human colon carcinoma cells (HCT116) revealed that compound 3g exhibited potent inhibitory effect on HCT116 cancer cells with an IC₅₀ value of 6.37 μM, representing a novel lead compound for further structural optimization and biological evaluation.

The Involvement of PDE4 in the Protective Effects of Melatonin on Cigarette-Smoke-Induced Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a significant disease threatening human health. Currently, roflumilast, a phosphodiesterase (PDE)4 inhibitor, is recommended as a therapeutic agent for COPD. In this study, we investigated the therapeutic effects of melatonin against COPD, focusing on determining whether it is a PDE4 inhibitor via in vivo and in vitro experiment using cigarette smoke (CS) and cigarette smoke condensate (CSC), respectively. In the in vivo experiments, melatonin treatment reduced inflammatory responses, including inflammatory cell counts. Melatonin treatment also suppressed the CS-exposure-induced upregulation of cytokine and matrix metalloproteinase (MMP)-9, reduced the PDE4B expression, and elevated cAMP levels. In addition, these effects were synergistic, as melatonin and roflumilast cotreatment eventually ameliorated the CS-exposure-induced worsening of lung function. In the CSC-stimulated NCI-H292 cells, melatonin inhibited elevation in the levels of inflammatory cytokines, MMP-9, and PDE4, and elevated cAMP levels. Furthermore, melatonin and roflumilast cotreatment was more effective on inflammatory responses than only melatonin or roflumilast treatment. Our results indicate that melatonin relieves inflammatory response and loss of lung function in COPD, which is associated with decreased PDE4 expression. Therefore, we suggest that melatonin is a putative candidate for the treatment of COPD.

Pyridazinone derivatives as potential anti-inflammatory agents: synthesis and biological evaluation as PDE4 inhibitors

Cyclic nucleotide phosphodiesterase type 4 (PDE4), which controls the intracellular level of cyclic adenosine monophosphate (cAMP), has aroused scientific attention as a suitable target for anti-inflammatory therapy of respiratory diseases. This work describes the development and characterization of pyridazinone derivatives bearing an indole moiety as potential PDE4 inhibitors and their evaluation as anti-inflammatory agents. Among these derivatives, 4-(5-methoxy-1H-indol-3-yl)-6-methylpyridazin-3(2H)-one possesses promising activity, and selectivity towards PDE4B isoenzymes and is able to regulate potent pro-inflammatory cytokine and chemokine production by human primary macrophages.

Enfermedad pulmonar obstructiva crónica (EPOC) Bases para el médico general

Chronic obstructive pulmonary disease (COPD) is a chronic degenerative disease. It is a frequent, preventable and treatable disease characterized by persistent respiratory symptoms and airflow limitation. The National Institute of Respiratory Diseases (INER), ranked COPD in 2016 in fourth place in the table of annual morbidity and mortality in Mexico. The prevalence of COPD is directly related to smoking; however, its development is multifactorial. For its study it is important to know of any prior exposure to risk factors and of any manifestation of the main symptoms. To make a diagnosis, a detailed clinical history, where the largest amount of data is collected from every new possible COPD patient, and a spirometry are essential. Individual pharmacological treatment is necessary due to the great variability among COPD patients. The drugs used in the treatment of COPD reduce the symptoms, the frequency and severity of exacerbations; however, there is no medication that modifies the long-term deterioration of the lung function. Therefore, a basic knowledge of this condition by the medical doctor first contacted, is essential for the suspicion of COPD in its initial stage and thus, offer the patient immediate medical intervention. The objective of the present work is to provide a basic overview of COPD to the general practitioner. Key words:Chronic obstructive pulmonary disease; biomass; tobacco; chronic obstructive bronchitis; emphysema; respiratory system

Modificated Mahuang-Tang, a traditional herbal medicine suppresses inflammatory responses induced by cigarette smoke in human airway epithelial cell and mice

BACKGROUND

Cigarette smoke (CS) is a major contributor to the high incidence of chronic obstructive pulmonary disease (COPD) featured as chronic inflammation and airway obstruction. Mahuang-Tang is a traditional polyherbal mixture composed of four different herbs. It is widely used in Asia as a remedy for allergic reaction and inflammation.

PURPOSE

We investigated the effects of a modificated Mahuang-Tang water extract (MTWE) against airway inflammation caused by CS and lipopolysaccharide (LPS) in mice and cigarette smoke condensate (CSC)-stimulated NCI-H292 cells.

METHODS

CS exposed to animals for 1 h per day from day 1 to day 7 and treated with LPS intranasally on day 4. One hour before CS exposure, animals were received MTWE (50 or 100 mg/kg) by oral gavage. Inflammatory cell count and cytokines levels were measured in the bronchoalveolar lavage fluid. Expression levels of matrix metalloprotease-9 (MMP-9) and extracellular signal-regulated kinase (Erk) were analyzed by western blotting.

RESULTS

MTWE markedly decreased the neutrophil and other inflammatory cell counts in the bronchoalveolar lavage fluid and reduced proinflammatory mediators as evidenced by the decreases in inflammatory cell recruitment in lung tissue. Furthermore, MTWE meaningfully declined MMP-9 expression and reduced the Erk phosphorylation, caused by the CS and LPS exposure. In in vitro experiments, MTWE suppressed the elevated expression of proinflammatory cytokines induced by CSC treatment. MTWE reduced Erk phosphorylation and MMP-9 expression in CSC-stimulated H292 cells.

CONCLUSION

Overall, MTWE effectively inhibited the pulmonary inflammation and MMP-9 expression caused by the CS and LPS exposure, which was closely involved in suppression of Erk phosphorylation. These results suggest that MTWE possesses a potential for the treatment of COPD.

Dexamethasone Inhibits Synergistic Induction of PDE4B Expression by Roflumilast and Bacterium NTHi

Phosphodiesterase 4B (PDE4B) plays an important role in inflammation. Recently we have reported that roflumilast as a PDE4-selective inhibitor, synergizes with nontypeable Haemophilus influenzae (NTHi) to up-regulate PDE4B expression in vitro and in vivo. Clinical evidence and our previous results suggest that synergistic induction of PDE4B could be counterproductive for suppressing inflammation or may contribute to tolerance to roflumilast. We thus investigated if dexamethasone inhibits the synergistic induction of PDE4B by roflumilast and NTHi as well as inflammation. Here, dexamethasone markedly suppressed the synergistic induction of PDE4B in human lung epithelial cells and in vivo. We also found that dexamethasone further suppressed NTHi-induced inflammatory response in vitro and in vivo. Moreover, Compound A, as a dissociating non-steroidal glucocorticoid receptor (GR) ligand, inhibited the synergistic induction of PDE4B, thereby suggesting the requirement of dexamethasone-mediated GR activation in the suppression of PDE4B expression. Taken together, our data suggest that dexamethasone may help attenuate inflammation and tolerance through suppressing the PDE4B expression in chronic obstructive pulmonary disease (COPD) patients using roflumilast.

Cardiovascular disease and COPD: dangerous liaisons?

Chronic obstructive pulmonary disease (COPD) and cardiovascular disease (CVD) frequently occur together and their coexistence is associated with worse outcomes than either condition alone. Pathophysiological links between COPD and CVD include lung hyperinflation, systemic inflammation and COPD exacerbations. COPD treatments may produce beneficial cardiovascular (CV) effects, such as long-acting bronchodilators, which are associated with improvements in arterial stiffness, pulmonary vasoconstriction, and cardiac function. However, data are limited regarding whether these translate into benefits in CV outcomes. Some studies have suggested that treatment with long-acting β₂-agonists and long-acting muscarinic antagonists leads to an increase in the risk of CV events, particularly at treatment initiation, although the safety profile of these agents with prolonged use appears reassuring. Some CV medications may have a beneficial impact on COPD outcomes, but there have been concerns about β-blocker use leading to bronchospasm in COPD, which may result in patients not receiving guideline-recommended treatment. However, there are few data suggesting harm with these agents and patients should not be denied β-blockers if required. Clearer recommendations are necessary regarding the identification and management of comorbid CVD in patients with COPD in order to facilitate early intervention and appropriate treatment.

Design and characterization of emulsified spray dried alginate microparticles as a carrier for the dually acting drug roflumilast

Roflumilast is a selective inhibitor of phosphodiesterase-4 isoenzyme in lung cells. Having psychiatric adverse reactions when administered orally affects negatively the patients' adherence to the drug. This work aimed to prepare emulsified spray dried alginate microparticles for the pulmonary delivery of roflumilast. Sodium alginate was used as microparticle-forming material, isopropyl myristate as an oil, Tween®80 as surfactant and calcium beta-glycerophosphate as cross-linking agent to enhance the mechanical properties of the particles. The prepared particles were evaluated for their encapsulation efficiency, particle size and in-vitro drug release. From the studied carriers, beta-cyclodextrin (CD) was the best regarding giving formulation with smaller particle size and more sustained drug release. The inhalation profile of CD-based microparticles was investigated using Anderson cascade impactor. The aerosolization profile of CD-based microparticles suggested their efficiency to deliver the drug deep in the lung. The CD-based microparticles possessed more inhibitory effects on the viability of A549 cells and on the pro-inflammatory cytokines (TNF-α, IL-6 and IL-10) compared to the pure drug. Hence, CD-based microparticles could regulate the tumorigenesis besides tumor-associated inflammation. Finally, CD-based microparticles showed more sustained bronchodilatation properties in healthy human volunteers when compared to Ventolin®HFA. CD-based microparticles proved to be a promising carrier for inhaled roflumilast in human.

Synthesis and biological evaluation of pyridazinone derivatives as potential anti-inflammatory agents

Cyclic nucleotide phosphodiesterase type 4 (PDE4), that controls intracellular level of cyclic nucleotide cAMP, has aroused scientific attention as a suitable target for anti-inflammatory therapy in respiratory diseases. Here we describe the development of two families of pyridazinone derivatives as potential PDE4 inhibitors and their evaluation as anti-inflammatory agents. Among these derivatives, 4,5-dihydropyridazinone representatives possess promising activity, selectivity towards PDE4 isoenzymes and are able to reduce IL-8 production by human primary polymorphonuclear cells.

Risk factors for the discontinuation of roflumilast in patients with chronic obstructive pulmonary disease

Introduction

Roflumilast is a phosphodiesterase-4 inhibitor, which can decrease exacerbation in patients with chronic obstructive pulmonary disease (COPD). However, adverse effects are a major barrier to medication use, and little is known regarding the risk factors for discontinuation of roflumilast in COPD patients.

Method

A search of the clinical databases identified all patients who were prescribed roflumilast between December 2012 and April 2015 in the four hospitals of The Catholic University of Korea, Korea. The study subjects were limited to patients who had taken 500 μg of roflumilast. We studied the factors associated with drug discontinuation and drug adverse events by univariate and multivariate analyses.

Results

Among 154 eligible patients, 54 (35.1%) discontinued their roflumilast prescription. Most patients were elderly, male, current or former smokers, and had moderate-to-severe airflow limitation. Low–body mass index (BMI) patients were more likely to undergo drug discontinuation (1-unit decrease in BMI: odds ratio [OR] =1.165, p=0.006; BMI <23 kg/m²: OR =2.960, p=0.004). Fifty-five patients (35.7%) had adverse events. Loss of appetite, diarrhea, nausea, headache, and weight loss were the most frequent adverse events. Low-BMI patients were more likely to experience adverse events (1-unit decrease in BMI: OR =1.151, p=0.010; BMI <23 kg/m²: OR =2.644, p=0.009).

Conclusions

The patient discontinuation and adverse events rates in this study were higher than in previous randomized controlled studies. Discontinuation of roflumilast in ethnic Koreans is more likely to occur in low-BMI patients. In a clinical setting, low-BMI patients can more easily discontinue roflumilast; clinicians should, therefore, provide greater care for these patients.

4-Hydroxycinnamic acid protects mice from cigarette smoke-induced pulmonary inflammation via MAPK pathways

Cigarette smoke (CS) is the main etiological cause of chronic obstructive pulmonary disease, the prevalence of which has continuously increased in recent years. 4-Hydroxycinnamic acid (HA) is a plant phenolic acid that has anti-inflammatory activities. In this study, we explored the therapeutic effects of HA on airway inflammation caused by CS and lipopolysaccharide (LPS) in mice. The animals received 1 h of CS exposure for 7 days and intranasal instillation of LPS on day 4. HA (10 and 20 mg/kg) was administered to animals via oral gavage 1 h before CS exposure. HA treatment significantly decreased the accumulation of inflammatory cells and production of cytokines, including tumor necrosis factor-α, interleukin (IL)-6, and IL-1β, caused by CS and LPS exposure. After histological examination, we observed that HA treatment significantly reduced the infiltration of inflammatory cells into lung tissue caused by CS and LPS exposure. Furthermore, HA-treated groups showed significantly decreased phosphorylation of extracellular signal-regulated kinase, c-Jun N-terminal kinase, p38, and nuclear factor-κB, and activity of cytochrome c oxidase subunit-2 caused by CS and LPS. In conclusion, HA effectively suppresses the airway inflammatory response induced by CS and LPS exposure, and is closely associated with the downregulation of mitogen-activated protein kinases signaling.

Melatonin suppresses fibrotic responses induced by cigarette smoke via downregulation of TGF-β1

Cigarette smoke (CS) is the most important risk factor in the development of chronic obstructive pulmonary disease (COPD). Pulmonary fibrosis is an irreversible response and important feature of COPD. In this study, we investigated the effects of melatonin on fibrotic response in development of COPD using a CS and lipopolysaccharide (LPS) induced COPD model and cigarette smoke condensate (CSC)-stimulated NCI-H292 cells, a human mucoepidermoid cell line. Mice were exposed to CS for 1 h per day (8 cigarettes per day) from day 1 to day 7 and were treated intranasally with LPS on day 4. Melatonin (10 or 20 mg/kg) was injected intraperitoneally 1 h before CS exposure. Melatonin decreased the inflammatory cell counts in bronchoalveolar lavage fluid (BALF), with a reduction in transforming growth factor (TGF)-β1. Melatonin inhibited the expression of TGF-β1, collagen I and SMAD3 phosphorylation in lung tissue exposed to CS and LPS. In CSC-stimulated H292 cells, melatonin suppressed the elevated expression of fibrotic mediators induced by CSC treatment. Melatonin reduced the expression of TGF-β1, collagen I, SMAD3 and p38 phosphorylation in CSC-stimulated H292 cells. In addition, cotreatment with melatonin and TGF-β1 inhibitors significantly limited fibrotic mediators, with greater reductions in the expression of TGF-β1, collagen I, SMAD3 and p38 phosphorylation than those of H292 cells treated with TGF-β1 inhibitor alone. Taken together, melatonin effectively inhibited fibrotic responses induced by CS and LPS exposure, which was related to the downregulation of TGF-β1. Therefore, our results suggest that melatonin may suppress the pulmonary fibrotic response induced by CS.

Rational design of conformationally constrained oxazolidinone-fused 1,2,3,4-tetrahydroisoquinoline derivatives as potential PDE4 inhibitors

Improvement of subtype selectivity of an inhibitor's binding activity using the conformational restriction approach has become an effective strategy in drug discovery. In this study, we applied this approach to PDE4 inhibitors and designed a series of novel oxazolidinone-fused 1,2,3,4-tetrahydroisoquinoline derivatives as conformationally restricted analogues of rolipram. The bioassay results demonstrated the oxazolidinone-fused tetrahydroisoquinoline derivatives exhibited moderate to good inhibitory activity against PDE4B and high selectivity for PDE4B/PDE4D. Among these derivatives, compound 12 showed both the strongest inhibition activity (IC₅₀=0.60μM) as well as good selectivity against PDE4B and good in vivo activity in animal models of asthma/COPD and sepsis induced by LPS. The primary SAR study showed that restricting the conformation of the catechol moiety in rolipram with the scaffold of oxazolidinone-fused tetrahydroisoquinoline could lead to an increase in selectivity for PDE4B over PDE4D, which was consistent with the observed docking simulation.

Pine bark extract (Pycnogenol®) suppresses cigarette smoke-induced fibrotic response via transforming growth factor-β1/Smad family member 2/3 signaling

Chronic obstructive pulmonary diseases (COPD) is an important disease featured as intense inflammation, protease imbalance, and air flow limitation and mainly induced by cigarette smoke (CS). In present study, we explored the effects of Pycnogenol® (PYC, pine bark extract) on pulmonary fibrosis caused by CS+lipopolysaccharide (LPS) exposure. Mice were treated with LPS intranasally on day 12 and 26, followed by CS exposure for 1 h/day (8 cigarettes per day) for 4 weeks. One hour before CS exposure, 10 and 20 mg/kg of PYC were administered by oral gavage for 4 weeks. PYC effectively reduced the number of inflammatory cells and proinflammatory mediators caused by CS+LPS exposure in bronchoalveolar lavage fluid. PYC inhibited the collagen deposition on lung tissue caused by CS+LPS exposure, as evidenced by Masson's trichrome stain. Furthermore, transforming growth factor-β1 (TGF-β1) expression and Smad family member 2/3 (Smad 2/3) phosphorylation were effectively suppressed by PYC treatment. PYC markedly reduced the collagen deposition caused by CS+LPS exposure, which was closely involved in TGF-β1/Smad 2/3 signaling, which is associated with pulmonary fibrotic change. These findings suggest that treatment with PYC could be a therapeutic strategy for controlling COPD progression.

Discovery of N-Alkyl Catecholamides as Selective Phosphodiesterase-4 Inhibitors with Anti-neuroinflammation Potential Exhibiting Antidepressant-like Effects at Non-emetic Doses

Depression involving neuroinflammation is one of the most common disabling and life-threatening psychiatric disorders. Phosphodiesterase 4 (PDE4) inhibitors produce potent antidepressant-like and cognition-enhancing effects. However, their clinical utility is limited by their major side effect of emesis. To obtain more selective PDE4 inhibitors with antidepressant and anti-neuroinflammation potential and less emesis, we designed and synthesized a series of N-alkyl catecholamides by modifying the 4-methoxybenzyl group of our hit compound, FCPE07, with an alkyl side chain. Among these compounds, 10 compounds displayed submicromolar IC₅₀ values in the mid- to low-nanomolar range. Moreover, 4-difluoromethoxybenzamides 10g and 10j, bearing isopropyl groups, exhibited the highest PDE4 inhibitory activities, with IC₅₀ values in the low-nanomolar range and with higher selectivities for PDE4 (approximately 5000-fold and 2100-fold over other PDEs, respectively). Furthermore, compound 10j displayed anti-neuroinflammation potential, promising antidepressant-like effects, and a zero incidence rate of emesis at 0.8 mg/kg within 180 min.

Development of highly potent phosphodiesterase 4 inhibitors with anti-neuroinflammation potential: Design, synthesis, and structure-activity relationship study of catecholamides bearing aromatic rings

In this study, catecholamides (7a-l) bearing different aromatic rings (such as pyridine-2-yl, pyridine-3-yl, phenyl, and 2-chlorophenyl groups) were synthesized as potent phosphodiesterase (PDE) 4 inhibitors. The inhibitory activities of these compounds were evaluated against the core catalytic domains of human PDE4 (PDE4CAT), full-length PDE4A4, PDE4B1, PDE4C1, and PDE4D7 enzymes, and other PDE family members. Eight of the synthesized compounds were identified as having submicromolar IC₅₀ values in the mid-to low-nanomolar range. Careful analysis on the structure-activity relationship of compounds 7a-l revealed that the replacement of the 4-methoxy group with the difluoromethoxy group improved inhibitory activities. More interesting, 4-difluoromethoxybenzamides 7i and 7j exhibited preference for PDE4 with higher selectivities of about 3333 and 1111-fold over other PDEs, respectively. In addition, compound 7j with wonderful PDE4D7 inhibitory activities inhibited LPS-induced TNF-α production in microglia.

Effects of roflumilast in COPD patients receiving inhaled corticosteroid/long-acting β2-agonist fixed-dose combination: RE(2)SPOND rationale and study design

Background

Roflumilast, a once-daily, selective phosphodiesterase-4 inhibitor, reduces the risk of COPD exacerbations in patients with severe COPD associated with chronic bronchitis and a history of exacerbations. The RE²SPOND study is examining whether roflumilast, when added to an inhaled corticosteroid/long-acting β₂-agonist (ICS/LABA) fixed-dose combination (FDC), further reduces exacerbations. The methodology is described herein.

Methods

In this Phase IV, multicenter, double-blind, placebo-controlled, parallel-group trial, participants were randomized 1:1 (stratified by long-acting muscarinic antagonist use) to receive roflumilast or placebo, plus ICS/LABA FDC, for 52 weeks. Eligible participants had severe COPD associated with chronic bronchitis, had two or more moderate–severe exacerbations within 12 months, and were receiving ICS/LABA FDC for ≥3 months. The primary efficacy measure is the rate of moderate or severe COPD exacerbations per participant per year. The secondary efficacy outcomes include mean change in prebronchodilator forced expiratory volume in 1 second (FEV₁) over 52 weeks, rate of severe exacerbations, and rate of moderate, severe, or antibiotic-treated exacerbations. Additional assessments include spirometry, rescue medication use, the COPD assessment test, daily symptoms using the EXACT-Respiratory symptoms (E-RS) questionnaire, all-cause and COPD-related hospitalizations, and safety and pharmacokinetic measures.

Results

Across 17 countries, 2,354 participants were randomized from September 2011 to October 2014. Enrollment goal was met in October 2014, and study completion occurred in June 2016.

Conclusion

This study will further characterize the effects of roflumilast added to ICS/LABA on exacerbation rates, lung function, and health of severe–very severe COPD participants at risk of further exacerbations. The results will determine the clinical benefits of roflumilast combined with standard-of-care inhaled COPD treatment.

Airway bacteria drive a progressive COPD-like phenotype in mice with polymeric immunoglobulin receptor deficiency

Mechanisms driving persistent airway inflammation in chronic obstructive pulmonary disease (COPD) are incompletely understood. As secretory immunoglobulin A (SIgA) deficiency in small airways has been reported in COPD patients, we hypothesized that immunobarrier dysfunction resulting from reduced SIgA contributes to chronic airway inflammation and disease progression. Here we show that polymeric immunoglobulin receptor-deficient (pIgR^−/−) mice, which lack SIgA, spontaneously develop COPD-like pathology as they age. Progressive airway wall remodelling and emphysema in pIgR^−/− mice are associated with an altered lung microbiome, bacterial invasion of the airway epithelium, NF-κB activation, leukocyte infiltration and increased expression of matrix metalloproteinase-12 and neutrophil elastase. Re-derivation of pIgR^−/− mice in germ-free conditions or treatment with the anti-inflammatory phosphodiesterase-4 inhibitor roflumilast prevents COPD-like lung inflammation and remodelling. These findings show that pIgR/SIgA deficiency in the airways leads to persistent activation of innate immune responses to resident lung microbiota, driving progressive small airway remodelling and emphysema.

The mechanisms driving lung inflammation and remodelling in chronic obstructive pulmonary disease (COPD) are incompletely understood. Here the authors show that lack of secretory IgA promotes bacterial invasion in small airways, resulting in leukocyte recruitment and a COPD-like phenotype.

Tuberostemonine N, an active compound isolated from Stemona tuberosa, suppresses cigarette smoke-induced sub-acute lung inflammation in mice

OBJECTIVE

Our previous study demonstrated that a Stemona tuberosa extract had significant effects on cigarette smoking (CS)-induced lung inflammation in mice. The present study evaluated the potential of tuberostemonine N (T.N) to prevent airway inflammation and suppress airway responses in a CS-induced in vivo COPD model.

METHODS

T.N was isolated from the root of ST and analyzed using 1D and 2D NMR. The purity of T.N was accessed using HPLC-ELSD analysis. C57BL/6 mice in this study were whole-body exposed to mainstream CS or room air for 4 weeks, and T.N (1, 5 and 10 mg/kg body wt.) was administered to mice via intraperitoneal (i.p.) injection before CS exposure. The number of inflammatory cells, including neutrophils, macrophages and lymphocytes, and the amount of proinflammatory cytokines and chemokines were accessed from bronchoalveolar lavage fluid (BALF) to investigate the anti-inflammatory effects of T.N. Average alveoli size was also measured using histological analyses.

RESULTS

Cellular profiles and histopathological analyses revealed that the infiltration of peribronchial and perivascular inflammatory cells decreased significantly in the T.N-treated groups compared to the CS-exposed control group. T.N significantly inhibited the secretion of proinflammatory cytokines and chemokines in BALF and decreased alveoli size in lung tissue.

CONCLUSIONS

These data suggest that T.N exerts anti-inflammatory effects against airway inflammation, and T.N may be a novel therapeutic agent for lung diseases, such as COPD.

Protective effect of EC-18, a synthetic monoacetyldiglyceride on lung inflammation in a murine model induced by cigarette smoke and lipopolysaccharide

The antler of Sika deer (Cervus nippon Temminck) has been used a natural medicine in Korea, China and Japan, and a monoacetyldiaglyceride (1-palmitoyl-2-linoleoyl-3-acetylglycerol, PLAG) was found in the antler of Sika deer as a constituent for immunomodulation. In this study, we investigated protective effects of EC-18 (a synthetic copy of PLAG) on inflammatory responses using a cigarette smoke with lipopolysaccharide (LPS)-induced airway inflammation model. Mice were exposed to cigarette smoke for 1h per day for 3days. Ten micrograms of LPS dissolved in 50μL of PBS was administered intra nasally 1h after the final cigarette smoke exposure. EC-18 was administered by oral gavage at doses of 30 and 60mg/kg for 3days. EC-18 significantly reduced the number of neutrophils, reactive oxygen species production, cytokines and elastase activity in bronchoalveolar lavage fluid (BALF) compared with the cigarette smoke and LPS induced mice. Histologically, EC-18 attenuated airway inflammation with a reduction in myeloperoxidase expression in lung tissue. Additionally, EC-18 inhibited the phosphorylation of NF-κB and IκB induced by cigarette smoke and LPS exposure. Our results show that EC-18 effectively suppresses neutrophilic inflammation induced by cigarette smoke and LPS exposure. In conclusion, this study suggests that EC-18 has therapeutic potential for the treatment of chronic obstructive pulmonary disease.

Direct molecular targets of resveratrol: identifying key interactions to unlock complex mechanisms

To truly understand the mechanisms through which resveratrol exerts its biological effects, the key direct interactions between resveratrol and its target biomolecules must be identified. With an increasing number of biochemical tools to measure and quantify direct physical interactions between biomolecules, there have been around 20 proteins identified as having a specific affinity to resveratrol to date. Resveratrol has been described as a promiscuous molecule, and one would expect it to bind with numerous proteins, which would help explain why resveratrol appears to have so many health benefits and has been shown to act upon various different pathways related to a diverse range of conditions. The aim of this review is to present the direct protein targets of resveratrol that are currently known and highlight the consequences of direct binding and the methods used to identify the nature of these interactions.

Cross-talk between PKA-Cβ and p65 mediates synergistic induction of PDE4B by roflumilast and NTHi

Phosphodiesterase 4B (PDE4B) plays a key role in regulating inflammation. Roflumilast, a phosphodiesterase (PDE)4-selective inhibitor, has recently been approved for treating severe chronic obstructive pulmonary disease (COPD) patients with exacerbation. However, there is also clinical evidence suggesting the development of tachyphylaxis or tolerance on repeated dosing of roflumilast and the possible contribution of PDE4B up-regulation, which could be counterproductive for suppressing inflammation. Thus, understanding how PDE4B is up-regulated in the context of the complex pathogenesis and medications of COPD may help improve the efficacy and possibly ameliorate the tolerance of roflumilast. Here we show that roflumilast synergizes with nontypeable Haemophilus influenzae (NTHi), a major bacterial cause of COPD exacerbation, to up-regulate PDE4B2 expression in human airway epithelial cells in vitro and in vivo. Up-regulated PDE4B2 contributes to the induction of certain important chemokines in both enzymatic activity-dependent and activity-independent manners. We also found that protein kinase A catalytic subunit β (PKA-Cβ) and nuclear factor-κB (NF-κB) p65 subunit were required for the synergistic induction of PDE4B2. PKA-Cβ phosphorylates p65 in a cAMP-dependent manner. Moreover, Ser276 of p65 is critical for mediating the PKA-Cβ-induced p65 phosphorylation and the synergistic induction of PDE4B2. Collectively, our data unveil a previously unidentified mechanism underlying synergistic up-regulation of PDE4B2 via a cross-talk between PKA-Cβ and p65 and may help develop new therapeutic strategies to improve the efficacy of PDE4 inhibitor.

Fluorine in medicinal chemistry

Since its first use in the steroid field in the late 1950s, the use of fluorine in medicinal chemistry has become commonplace, with the small electronegative fluorine atom being a key part of the medicinal chemist's repertoire of substitutions used to modulate all aspects of molecular properties including potency, physical chemistry and pharmacokinetics. This review will highlight the special nature of fluorine, drawing from a survey of marketed fluorinated pharmaceuticals and the medicinal chemistry literature, to illustrate key concepts exploited by medicinal chemists in their attempts to optimize drug molecules. Some of the potential pitfalls in the use of fluorine will also be highlighted.

Emerging therapeutic strategies in COPD

Chronic obstructive pulmonary disease (COPD) management is changing with the advent of newer inhaled medications and devices that belong to the current group of therapies [i.e. inhaled corticosteroid (ICS), long-acting β2 agonists (LABAs) and long-acting muscarinic antagonists (LAMAs)], providing patients as well as physicians with a wider range of options. In this review, we examine Phase II studies currently underway in COPD patients. With improved understanding of the condition, the role for biological and immunomodulatory therapies in COPD patients is also an interesting and important aspect looked upon with great enthusiasm. It is indeed interesting to note that the future COPD treatment options could include novel interventional strategies in addition to innovative inhaled therapies, which have been the backbone of COPD management for the past couple of decades.

Novel Roflumilast analogs as soft PDE4 inhibitors

PDE4 inhibitors are of high interest for treatment of a wide range of inflammatory or autoimmune diseases. Their potential however has not yet been realized due to target-associated side effects, resulting in a low therapeutic window. We herein report the design, synthesis and evaluation of novel PDE4 inhibitors containing a γ-lactone structure. Such molecules are designed to undergo metabolic inactivation when entering circulation, thereby limiting systemic exposure and reducing the risk for side effects. The resulting inhibitors were highly active on both PDE4B1 and PDE4D2 and underwent rapid degradation in human plasma by paraoxonase 1. In contrast, their metabolites displayed markedly reduced permeability and/or on-target activity.

Gaining the Upper Hand on Pulmonary Drug Delivery

Asthma, Chronic Obstructive Pulmonary Disease (COPD) and Cystic Fibrosis (CF) are all pulmonary diseases which are characterized by chronic inflammation and an increase in mucus production. Excess mucus in the airways correlates with pathophysiology such as a decline in lung function and prolonged bacterial infections. New drugs to treat these chronic respiratory diseases are currently being developed and include both inhaled and orally administered compounds. Whilst oral drugs may be easier to administer, they are more prone to side-effects due to higher bioavailability. Inhaled compounds may show reduced bioavailability, but face their own unique challenges. For example, thick mucus in the respiratory tracts of asthma, CF and COPD patients can act as a physical barrier that impedes drug delivery. Mucus also contains a high number of enzymes and proteases that may degrade compounds before they reach their site of action. Furthermore, some classes of drugs are rapidly absorbed across the respiratory epithelia into systemic circulation, which may limit their duration of action and/or cause off-target effects. This review discusses some of the different treatment options that are currently available and the considerations that need to be taken into account to produce new therapies for the treatment of chronic respiratory diseases.