PDE4 inhibitors in COPD—a more selective approach to treatment

Targeting Striatal Glutamate and Phosphodiesterases to Control L-DOPA-Induced Dyskinesia

A large body of work during the past several decades has been focused on therapeutic strategies to control L-DOPA-induced dyskinesias (LIDs), common motor complications of long-term L-DOPA therapy in Parkinson's disease (PD). Yet, LIDs remain a clinical challenge for the management of patients with advanced disease. Glutamatergic dysregulation of striatal projection neurons (SPNs) appears to be a key contributor to altered motor responses to L-DOPA. Targeting striatal hyperactivity at the glutamatergic neurotransmission level led to significant preclinical and clinical trials of a variety of antiglutamatergic agents. In fact, the only FDA-approved treatment for LIDs is amantadine, a drug with NMDAR antagonistic actions. Still, novel agents with improved pharmacological profiles are needed for LID therapy. Recently other therapeutic targets to reduce dysregulated SPN activity at the signal transduction level have emerged. In particular, mechanisms regulating the levels of cyclic nucleotides play a major role in the transduction of dopamine signals in SPNs. The phosphodiesterases (PDEs), a large family of enzymes that degrade cyclic nucleotides in a specific manner, are of special interest. We will review the research for antiglutamatergic and PDE inhibition strategies in view of the future development of novel LID therapies.

PDE4 Inhibitors: Profiling Hits through the Multitude of Structural Classes

Cyclic nucleotide phosphodiesterases 4 (PDE4) are a family of enzymes which specifically promote the hydrolysis and degradation of cAMP. The inhibition of PDE4 enzymes has been widely investigated as a possible alternative strategy for the treatment of a variety of respiratory diseases, including chronic obstructive pulmonary disease and asthma, as well as psoriasis and other autoimmune disorders. In this context, the identification of new molecules as PDE4 inhibitors continues to be an active field of investigation within drug discovery. This review summarizes the medicinal chemistry journey in the design and development of effective PDE4 inhibitors, analyzed through chemical classes and taking into consideration structural aspects and binding properties, as well as inhibitory efficacy, PDE4 selectivity and the potential as therapeutic agents.

Design and synthesis of a novel class of PDE4 inhibitors with antioxidant properties as bifunctional agents for the potential treatment of COPD

It is well known that chronic obstructive pulmonary disease (COPD) patients are always trapped in the vicious circle of inflammation and oxidative stress, therefore anti-inflammatory and antioxidant bifunctional agents may interrupt this vicious cycle in COPD. Phosphodiesterase 4 (PDE4) inhibitors, as anti-inflammatory drugs, have been used for COPD treatment in clinical, and the PDE4 inhibitors with antioxidant properties may be a good strategy to design bifunctional agents for COPD. Sappanone A was the first PDE4 inhibitor with antioxidant properties we identified from natural products in our previous study, which was used by us as a hit compound to design new bifunctional agents for COPD in this study. 27 derivatives of sappanone A including homoisoflavonoids, aurones and chalcones were designed and synthesized by innovatively fusing the antioxidant pharmacophore of catechol from polyphenols and the pharmacophore of catechol ether abstracted from the PDE4 inhibitors of the catechol ether class such as rolipram, roflumilast and apremilast respectively. All the compounds were assayed for the PDE4 inhibitory and radical scavenging against 2, 2-diphenyl-1-picrylhydrazyl (DPPH) activities in vitro. Herein we obtained a series of bifunctional compounds with better PDE4 inhibitory activity than sappanone A, and their free radical scavenging activities were superior to edaravone in vitro. In addition, they can reduce tumour necrosis factor-alpha (TNF-α) production induced by lipopolysaccharide (LPS) in RAW264.7 macrophages and malondialdehyde (MDA) production induced by Fe²⁺ in mouse lung homogenate. Meanwhile, it showed outstanding abilities in reducing Fe³⁺ and complexing Fe²⁺. 6o, as the candidate anti-inflammatory and antioxidant bifunctional compound, exhibited good drug-likeness, ADME (Absorption, Distribution, Metabolism, Excretion) properties and human liver microsomal stability. In vivo, 6o (50 mg/kg and 100 mg/kg, i. p.) distinctly prevented LPS-induced serum levels of TNF-α in mice. In conclusion, the preliminary investigation provided a novel class of PDE4 inhibitors with antioxidant properties as bifunctional agents for the potential treatment of COPD, which can interrupt the vicious cycle of chronic inflammation and oxidative stress in COPD.

Sappanone A: A natural PDE4 inhibitor with dual anti-inflammatory and antioxidant activities from the heartwood of Caesalpinia sappan L

ETHNOPHARMACOLOGICAL RELEVANCE

Sumu (Lignum sappan), the dry heartwood of Caesalpinia sappan L., is a traditional Chinese medicine used as an analgesic and anti-inflammatory agent.

AIM OF THE STUDY

The study aspired to discover natural phosphodiesterase 4 (PDE4) inhibitors with dual anti-inflammatory and antioxidant activities from Sumu for the treatment of chronic obstructive pulmonary disease (COPD).

MATERIALS AND METHODS

To accurately and efficiently identify natural PDE4 inhibitors from Sumu, molecular docking and molecular dynamics (MD) analysis methods were used for structure-based virtual screening of a self-built database of primary polyphenols in Sumu. According to the previous studies of Sumu and the free radical scavenging mechanism of polyphenols, the reported antioxidant components from Sumu and the potential antioxidants with the antioxidant pharmacophore of catechol and π-conjugated moieties were selected from the potential PDE4 inhibitors predicted by docking. Sappanone A, a potential PDE4 inhibitor with antioxidant activity from Sumu, was selected, calculated and synthesized to evaluate its dual anti-inflammatory and antioxidant functions in vitro and in vivo studies. Herein sappanone A was assayed for its inhibitory effects against PDE4 enzyme activity, tumor necrosis factor-alpha (TNF-α) production induced by lipopolysaccharide (LPS) in RAW264.7 macrophages and malondialdehyde (MDA) production induced by Fe²⁺ in mouse lung homogenate; sappanone A was also assayed for its abilities of radical (DPPH) scavenging, reducing Fe³⁺ and complexing Fe²⁺ in vitro. Additionally, LPS-induced acute lung injury (ALI) in mice was used to evaluate its anti-inflammatory activity as a PDE4 inhibitor in vivo, and the levels of TNF-α and total protein in bronchoalveolar lavage fluid (BALF) and myeloperoxidase (MPO) activity in the lung were assayed.

RESULTS

The present study predicted and validated that sappanone A was a promising PDE4 inhibitor from Sumu with dual anti-inflammation and antioxidant activities from Sumu. In vitro, sappanone A remarkably inhibited PDE4 enzyme activity and reduced TNF-α production induced by LPS in RAW264.7 macrophages and MDA production induced by Fe²⁺ in mouse lung homogenate. Meanwhile, it showed outstanding abilities of scavenging DPPH radicals, reducing Fe³⁺ and complexing Fe²⁺. In vivo, sappanone A (25 mg/kg and 50 mg/kg, i.p., twice daily for 7 days) distinctly prevented LPS-induced ALI in mice by reducing the levels of TNF-α and total protein in BALF and MPO activity in the lung.

CONCLUSION

Sappanone A is a natural PDE4 inhibitor with dual anti-inflammatory and antioxidant activities from the traditional Chinese medicine Sumu, which may be a promising therapeutic agent to prevent the vicious cycle of COPD inflammation and oxidative stress.

Multifunctional lipid-based nanocarriers with antibacterial and anti-inflammatory activities for treating MRSA bacteremia in mice

Background

Bacteremia-induced sepsis is a leading cause of mortality in intensive care units. To control a bacterial infection, an immune response is required, but this response might contribute to organ failure. Kidneys are one of the main organs affected by bacteremia. Combination therapies with antibacterial and anti-inflammatory effects may be beneficial in treating bacteremia. This study aimed to develop nanostructured lipid carriers (NLCs) loaded with ciprofloxacin and rolipram that exert a combination of anti-methicillin-resistant Staphylococcus aureus (MRSA) and anti-inflammatory effects. Retinol was incorporated into the nanoparticles to transport retinol-binding protein 4 (RBP4) to the kidneys, which abundantly express RBP receptors. The NLCs were fabricated by high-shear homogenization and sonication, and neutrophils were used as a model to assess their anti-inflammatory effects. Mice were injected with MRSA to establish a model of bacteremia with organ injury.

Results

The mean nanoparticle size and zeta potential of the NLCs were 171 nm and − 39 mV, respectively. Ciprofloxacin (0.05%, w/v) and rolipram (0.02%) achieved encapsulation percentages of 88% and 96%, respectively, in the nanosystems. The minimum bactericidal concentration of free ciprofloxacin against MRSA increased from 1.95 to 15.63 µg/ml when combined with rolipram, indicating a possible drug-drug interaction that reduced the antibacterial effect. Nanoparticle inclusion promoted the anti-MRSA activity of ciprofloxacin according to time-kill curves. The NLCs were found to be largely internalized into neutrophils and exhibited superior superoxide anion inhibition than free drugs. Retinol incorporation into the nanocarriers facilitated their efficient targeting to the kidneys. The NLCs significantly mitigated MRSA burden and elastase distribution in the organs of MRSA-infected animals, and the greatest inhibition was observed in the kidneys. Bacterial clearance and neutrophil infiltration suppression attenuated the bacteremia-induced cytokine overexpression, leading to an improvement in the survival rate from 22% to 67%.

Conclusions

The dual role of our NLCs endowed them with greater efficacy in treating MRSA bacteremia than that of free drugs.

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.

Current insights on clinical efficacy of roflumilast for treatment of COPD, asthma and ACOS

Phosphodiesterase-4 inhibitors (PDE4) are of great interest for the treatment of airway inflammatory diseases due to its broad anti-inflammatory effects. Roflumilast is a selective PDE4 inhibitor that inhibits pulmonary and systemic inflammation and rallies symptoms in airway diseases. Asthma and COPD are common chronic airway inflammatory diseases having incompletely illustrious pathophysiology and clinical manifestations. Recently, the condition called Asthma- COPD Overlap (ACO) has been evolved having the overlapping symptoms of both diseases. The newly discovered PDE4 inhibitor, roflumilast has exposed its potential in the treatment of Asthma, COPD and ACOS. Its mechanism of action in airway inflammatory diseases are said to be exerts by elevating intracellular cAMP and shows its anti-inflammatory action. Roflumilast, a promising therapeutic approach in inflammatory airway diseases, has many significant outcomes. In this review, we have provided various promising clinical evidences of roflumilast in COPD and asthma. However, there is no published clinical evidence to date for the role of roflumilast in ACOS. Nevertheless, there are therapeutic mechanisms that provide a reference for clinical application for ACOS.

Phosphodiesterase-4 enzyme as a therapeutic target in neurological disorders

Phosphodiesterases (PDE) are a diverse family of enzymes (11 isoforms so far identified) responsible for the degradation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) which are involved in several cellular and biochemical functions. Phosphodiesterase 4 (PDE4) is the major isoform within this group and is highly expressed in the mammalian brain. An inverse association between PDE4 and cAMP levels is the key mechanism in various pathophysiological conditions like airway inflammatory diseases-chronic obstruction pulmonary disease (COPD), asthma, psoriasis, rheumatoid arthritis, and neurological disorders etc. In 2011, roflumilast, a PDE4 inhibitor (PDE4I) was approved for the treatment of COPD. Subsequently, other PDE4 inhibitors (PDE4Is) like apremilast and crisaborole were approved by the Food and Drug Administration (FDA) for psoriasis, atopic dermatitis etc. Due to the adverse effects like unbearable nausea and vomiting, dose intolerance and diarrhoea, PDE4 inhibitors have very less clinical compliance. Efforts are being made to develop allosteric modulation with high specificity to PDE4 isoforms having better efficacy and lesser adverse effects. Interestingly, repositioning PDE4Is towards neurological disorders including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), multiple sclerosis (MS) and sleep disorders, is gaining attention. This review is an attempt to summarize the data on the effects of PDE4 overexpression in neurological disorders and the use of PDE4Is and newer allosteric modulators as therapeutic options. We have also compiled a list of on-going clinical trials on PDE4 inhibitors in neurological disorders.

Protective effects of rolipram on endotoxic cardiac dysfunction via inhibition of the inflammatory response in cardiac fibroblasts

BACKGROUND

Cardiac fibroblasts, regarded as the immunomodulatory hub of the heart, have been thought to play an important role during sepsis-induced cardiomyopathy (SIC). However, the detailed molecular mechanism and targeted therapies for SIC are still lacking. Therefore, we sought to investigate the likely protective effects of rolipram, an anti-inflammatory drug, on lipopolysaccharide (LPS)-stimulated inflammatory responses in cardiac fibroblasts and on cardiac dysfunction in endotoxic mice.

METHOD

Cardiac fibroblasts were isolated and stimulated with 1 μg/ml LPS for 6 h, and 10 μmol/l rolipram was administered for 1 h before LPS stimulation. mRNA levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) in fibroblasts and their protein concentrations in supernatant were measured with real-time PCR (rt-PCR) and enzyme-linked immunosorbent assay, respectively. The expression of dual specificity phosphatase 1 (DUSP1), an endogenous negative regulator that inactivates MAPK-mediated inflammatory pathways, was also measured by rt-PCR and western blotting. DUSP1-targeted small interfering RNA (siRNA) was used to examine the specific role of DUSP1. To evaluate the role of rolipram in vivo, an endotoxic mouse model was established by intraperitoneal injection of 15 mg/kg LPS, and 10 mg/kg rolipram was intraperitoneally injected 1 h before LPS injection. mRNA and protein levels of inflammatory cytokines and DUSP1 in heart, inflammatory cell infiltration and cardiac function were all examined at 6 h after LPS injection.

RESULTS

The results showed that LPS could increase the expression and secretion of inflammatory cytokines and decrease the transcription and expression of DUSP1 in cardiac fibroblasts. However, rolipram pretreatment significantly reversed the LPS-induced downregulation of DUSP1 and inhibited LPS-induced upregulation and secretion of TNF-α and IL-6 but not IL-1β. Moreover, DUSP1-targeted siRNA experiments indicated that the protective effect of rolipram on inflammatory response was specific dependent on DUSP1 expression. Moreover, rolipram could further reduce inflammatory cell infiltration scores as shown by pathological analysis and increase the ejection fraction (EF) detected with echocardiography in the hearts of endotoxic mice.

CONCLUSIONS

Rolipram could improve endotoxin-induced cardiac dysfunction by upregulating DUSP1 expression to inhibit the inflammatory response in cardiac fibroblasts, which may be a potential treatment for SIC.

Phosphodiesterase-4 inhibitors for chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is associated with cough, sputum production or dyspnoea, and a reduction in lung function, quality of life, and life expectancy. Apart from smoking cessation, no other treatments that slow lung function decline are available. Roflumilast and cilomilast are oral phosphodiesterase-4 (PDE₄) inhibitors proposed to reduce the airway inflammation and bronchoconstriction seen in COPD. This Cochrane Review was first published in 2011, and was updated in 2017 and 2020.

OBJECTIVES

To evaluate the efficacy and safety of oral PDE₄ inhibitors for management of stable COPD.

SEARCH METHODS

We identified randomised controlled trials (RCTs) from the Cochrane Airways Trials Register (date of last search 9 March 2020). We found other trials at web-based clinical trials registers.

SELECTION CRITERIA

We included RCTs if they compared oral PDE₄ inhibitors with placebo in people with COPD. We allowed co-administration of standard COPD therapy.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Two independent review authors selected trials for inclusion, extracted data, and assessed risk of bias. We resolved discrepancies by involving a third review author. We assessed our confidence in the evidence by using GRADE recommendations. Primary outcomes were change in lung function (minimally important difference (MID) = 100 mL) and quality of life (scale 0 to 100; higher score indicates more limitations).

MAIN RESULTS

We found 42 RCTs that met the inclusion criteria and were included in the analyses for roflumilast (28 trials with 18,046 participants) or cilomilast (14 trials with 6457 participants) or tetomilast (1 trial with 84 participants), with a duration between six weeks and one year or longer. These trials included people across international study centres with moderate to very severe COPD (Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades II to IV), with mean age of 64 years. We judged risks of selection bias, performance bias, and attrition bias as low overall amongst the 39 published and unpublished trials. Lung function Treatment with a PDE₄ inhibitor was associated with a small, clinically insignificant improvement in forced expiratory volume in one second (FEV₁) over a mean of 40 weeks compared with placebo (mean difference (MD) 49.33 mL, 95% confidence interval (CI) 44.17 to 54.49; participants = 20,815; studies = 29; moderate-certainty evidence). Forced vital capacity (FVC) and peak expiratory flow (PEF) were also improved over 40 weeks (FVC: MD 86.98 mL, 95% CI 74.65 to 99.31; participants = 22,108; studies = 17; high-certainty evidence; PEF: MD 6.54 L/min, 95% CI 3.95 to 9.13; participants = 4245; studies = 6; low-certainty evidence). Quality of life Trials reported improvements in quality of life over a mean of 33 weeks (St George's Respiratory Questionnaire (SGRQ) MD -1.06 units, 95% CI -1.68 to -0.43; participants = 7645 ; moderate-certainty evidence). Incidence of exacerbations Treatment with a PDE₄ inhibitor was associated with a reduced likelihood of COPD exacerbation over a mean of 40 weeks (odds ratio (OR) 0.78, 95% CI 0.73 to 0.84; participants = 20,382; studies = 27; high-certainty evidence), that is, for every 100 people treated with PDE₄ inhibitors, five more remained exacerbation-free during the study period compared with those given placebo (number needed to treat for an additional beneficial outcome (NNTB) 20, 95% CI 16 to 27). No change in COPD-related symptoms nor in exercise tolerance was found. Adverse events More participants in the treatment groups experienced an adverse effect compared with control participants over a mean of 39 weeks (OR 1.30, 95% CI 1.22 to 1.38; participants = 21,310; studies = 30; low-certainty evidence). Participants experienced a range of gastrointestinal symptoms such as diarrhoea, nausea, vomiting, or dyspepsia. Diarrhoea was more commonly reported with PDE₄ inhibitor treatment (OR 3.20, 95% CI 2.74 to 3.50; participants = 20,623; studies = 29; high-certainty evidence), that is, for every 100 people treated with PDE₄ inhibitors, seven more suffered from diarrhoea during the study period compared with those given placebo (number needed to treat for an additional harmful outcome (NNTH) 15, 95% CI 13 to 17). The likelihood of psychiatric adverse events was higher with roflumilast 500 µg than with placebo (OR 2.13, 95% CI 1.79 to 2.54; participants = 11,168; studies = 15 (COPD pool data); moderate-certainty evidence). Roflumilast in particular was associated with weight loss during the trial period and with an increase in insomnia and depressive mood symptoms. Participants treated with PDE₄ inhibitors were more likely to withdraw from trial participation; on average, 14% in the treatment groups withdrew compared with 8% in the control groups. Mortality No effect on mortality was found (OR 0.98, 95% CI 0.77 to 1.24; participants = 19,786; studies = 27; moderate-certainty evidence), although mortality was a rare event during these trials.

AUTHORS' CONCLUSIONS

For this current update, five new studies from the 2020 search contributed to existing findings but made little impact on outcomes described in earlier versions of this review. PDE₄ inhibitors offered a small benefit over placebo in improving lung function and reducing the likelihood of exacerbations in people with COPD; however, they had little impact on quality of life or on symptoms. Gastrointestinal adverse effects and weight loss were common, and the likelihood of psychiatric symptoms was higher, with roflumilast 500 µg. The findings of this review provide cautious support for the use of PDE₄ inhibitors in COPD. In accordance with GOLD 2020 guidelines, they may have a place as add-on therapy for a subgroup of people with persistent symptoms or exacerbations despite optimal COPD management (e.g. people whose condition is not controlled by fixed-dose long-acting beta₂-agonist (LABA) and inhaled corticosteroid (ICS) combinations). More longer-term trials are needed to determine whether or not PDE₄ inhibitors modify FEV₁ decline, hospitalisation, or mortality in COPD.

Developments in the field of allergy in 2016 through the eyes of Clinical and Experimental Allergy

In this article, we described the development in the field of allergy as described by Clinical and Experimental Allergy in 2016. Experimental models of allergic disease, basic mechanisms, clinical mechanisms, allergens, asthma and rhinitis, and clinical allergy are all covered.

MKP-1 negative regulates Staphylococcus aureus induced inflammatory responses in Raw264.7 cells: roles of PKA-MKP-1 pathway and enhanced by rolipram

MAP phosphatases (MKP)-1 acts as an important regulator of innate immune response through a mechanism of control and attention both MAPK and NF-κB molecules during bacterial infection. However, the regulatory role of MKP-1 in the interplay between MAPK and NFκB pathway molecules is still not fully understood. In present study, we showed a direct interactions of p38, ERK or IκBα with MKP-1, and demonstrated that MKP-1 was a pivotal feedback control for both MAP kinases and NF-κB pathway in response to S. aureus. In addition, we found that rolipram had anti-inflammatory activity and repressed IκBα activation induced by S. aureus via PKA-MKP-1 pathway. Our report also demonstrated that PKA-cα can directly bind to IκBα upon S. aureus stimulation, which influenced the downstream signaling of PKA pathway, including altered the expression of MKP-1. These results presented a novel mechanism of PKA and IκB pathway, which may be targeted for treating S. aureus infection.

Phosphodiesterase 4 inhibitors for chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is associated with cough, sputum production or dyspnoea and a reduction in lung function, quality of life and life expectancy. Apart from smoking cessation, there are no other treatments that slow lung function decline. Roflumilast and cilomilast are oral phosphodiesterase 4 (PDE4) inhibitors proposed to reduce the airway inflammation and bronchoconstriction seen in COPD. This is an update of a Cochrane review first published in 2011 and updated in 2013.

OBJECTIVES

To evaluate the efficacy and safety of oral PDE4 inhibitors in the management of stable COPD.

SEARCH METHODS

We identified randomised controlled trials (RCTs) from the Cochrane Airways Trials Register (date of last search October 2016). We found other trials from web-based clinical trials registers.

SELECTION CRITERIA

We included RCTs if they compared oral PDE4 inhibitors with placebo in people with COPD. We allowed co-administration of standard COPD therapy.

DATA COLLECTION AND ANALYSIS

One review author extracted data and a second review author checked the data. We reported pooled data in Review Manager as mean differences (MD), standardised mean differences (SMD) or odds ratios (OR). We converted the odds ratios into absolute treatment effects in a 'Summary of findings' table.

MAIN RESULTS

Thirty-four separate RCTs studying roflumilast (20 trials with 17,627 participants) or cilomilast (14 trials with 6457 participants) met the inclusion criteria, with a duration of between six weeks and one year. These included people across international study centres with moderate to very severe COPD (Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades II-IV), with a mean age of 64 years.We considered that the methodological quality of the 34 published and unpublished trials was acceptable overall. Treatment with a PDE4 inhibitor was associated with a significant improvement in forced expiratory volume in one second (FEV1) over the trial period compared with placebo (MD 51.53 mL, 95% confidence interval (CI) 43.17 to 59.90, 27 trials with 20,585 participants, moderate-quality evidence due to moderate levels of heterogeneity and risk of reporting bias). There were small improvements in quality of life (St George's Respiratory Questionnaire (SGRQ), MD -1.06 units, 95% CI -1.68 to -0.43, 11 trials with 7645 participants, moderate-quality evidence due to moderate levels of heterogeneity and risk of reporting bias) and COPD-related symptoms, but no significant change in exercise tolerance. Treatment with a PDE4 inhibitor was associated with a reduced likelihood of COPD exacerbation (OR 0.78, 95% CI 0.73 to 0.83; 23 trials with 19,948 participants, high-quality evidence). For every 100 people treated with PDE4 inhibitors, five more remained exacerbation-free during the study period compared with placebo (number needed to treat for an additional beneficial outcome (NNTB) 20, 95% CI 16 to 26). More participants in the treatment groups experienced non-serious adverse events compared with controls, particularly a range of gastrointestinal symptoms such as diarrhoea, nausea, vomiting or dyspepsia. For every 100 people treated with PDE4 inhibitors, seven more suffered from diarrhoea during the study period compared with placebo (number needed to treat for an additional harmful outcome (NNTH) 15, 95% CI 13 to 17). Roflumilast in particular was associated with weight loss during the trial period and an increase in insomnia and depressive mood symptoms. There was no significant effect of treatment on non-fatal serious adverse events (OR 0.99, 95% CI 0.91 to 1.07) or mortality (OR 0.97, 95% CI 0.76 to 1.23), although mortality was a rare event during the trials. Participants treated with PDE4 inhibitors were more likely to withdraw from the trials because of adverse effects; on average 14% in the treatment groups withdrew compared with 8% in the control groups.

AUTHORS' CONCLUSIONS

In people with COPD, PDE4 inhibitors offered benefit over placebo in improving lung function and reducing the likelihood of exacerbations; however, they had little impact on quality of life or symptoms. Gastrointestinal adverse effects and weight loss were common, and safety data submitted to the US Food and Drug Administration (FDA) have raised concerns over psychiatric adverse events with roflumilast. The findings of this review give cautious support to the use of PDE4 inhibitors in COPD. They may be best used as add-on therapy in a subgroup of people with persistent symptoms or exacerbations despite optimal COPD management. This is in accordance with the GOLD 2017 guidelines. Longer-term trials are needed to determine whether or not PDE4 inhibitors modify FEV1 decline, hospitalisation or mortality in COPD.

Recommendations for the pharmacological treatment of COPD: questions and answers

The treatment of COPD has become increasingly effective. Measures that range from behavioral changes, reduction in exposure to risk factors, education about the disease and its course, rehabilitation, oxygen therapy, management of comorbidities, and surgical and pharmacological treatments to end-of-life care allow health professionals to provide a personalized and effective therapy. The pharmacological treatment of COPD is one of the cornerstones of COPD management, and there have been many advances in this area in recent years. Given the greater availability of drugs and therapeutic combinations, it has become increasingly challenging to know the indications for, limitations of, and potential risks and benefits of each treatment modality. In order to critically evaluate recent evidence and systematize the major questions regarding the pharmacological treatment of COPD, 24 specialists from all over Brazil gathered to develop the present recommendations. A visual guide was developed for the classification and treatment of COPD, both of which were adapted to fit the situation in Brazil. Ten questions were selected on the basis of their relevance in clinical practice. They address the classification, definitions, treatment, and evidence available for each drug or drug combination. Each question was answered by two specialists, and then the answers were consolidated in two phases: review and consensus by all participants. The questions answered are practical questions and help select from among the many options the best treatment for each patient and his/her peculiarities.

Metabolomic profiles of current cigarette smokers

Smoking-related biomarkers for lung cancer and other diseases are needed to enhance early detection strategies and to provide a science base for tobacco product regulation. An untargeted metabolomics approach by ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UHPLC-Q-TOF MS) totaling 957 assays was used in a novel experimental design where 105 current smokers smoked two cigarettes 1 h apart. Blood was collected immediately before and after each cigarette allowing for within-subject replication. Dynamic changes of the metabolomic profiles from smokers' four blood samples were observed and biomarkers affected by cigarette smoking were identified. Thirty-one metabolites were definitively shown to be affected by acute effect of cigarette smoking, uniquely including menthol-glucuronide, the reduction of glutamate, oleamide, and 13 glycerophospholipids. This first time identification of a menthol metabolite in smokers' blood serves as proof-of-principle for using metabolomics to identify new tobacco-exposure biomarkers, and also provides new opportunities in studying menthol-containing tobacco products in humans. Gender and race differences also were observed. Network analysis revealed 12 molecules involved in cancer, notably inhibition of cAMP. These novel tobacco-related biomarkers provide new insights to the effects of smoking which may be important in carcinogenesis but not previously linked with tobacco-related diseases. © 2016 Wiley Periodicals, Inc.

The IL-17-Th1/Th17 pathway: an attractive target for lung cancer therapy?

INTRODUCTION

There is strong pharmaceutical development of agents targeting the IL-17-TH17 pathway for the treatment of psoriasis (Ps) and psoriatic arthritis (PsA). Lung cancer accounts for 28% of all cancer-related deaths worldwide, and roughly 80% of patients with newly-diagnosed non-small cell lung cancer (NSCLC) present with metastatic disease, with a poor prognosis of around 12 months. Therefore, there is a high unmet medical need for the development of new and potent systemic treatments in this deadly disease. The emergence of immunotherapies such as anti-PD-1 or anti-PDL1 as candidate therapies in non-small cell lung cancer (NSCLC) indicates that targeting critical immuno-modulatory cytokines including those within the IL-17-Th1/Th17 axis may have proven benefit in the treatment of lung cancer. Areas covered: In this review we describe the current evidence for aberrant IL-17-Th1/Th17 settings in cancer, particularly with regard to targeting this axis in NSCLC. We further discuss the current agents under pharmaceutical development which could potentially target this axis, and discuss the current limitations and areas of concern regarding the use of these in lung cancer. Expert opinion: Current evidence suggests that moving forward agents targeting the IL-17-Th1/Th17 pathway may have novel new oncoimmunology indications in the treatment paradigm for NSCLC.

Phosphodiesterase 4 inhibitors for the treatment of chronic obstructive pulmonary disease: a review of current and developing drugs

INTRODUCTION

Phosphodiesterase (PDE) inhibitors modulate lung inflammation and cause bronchodilation by increasing intracellular cyclic adenosine 3', 5'-monophosphate in airway smooth muscle and inflammatory cells. Roflumilast is the only approved PDE-4 inhibitor (PDE4I) for use in chronic obstructive pulmonary disease (COPD). Its beneficial clinical effects occur preferentially in patients with chronic bronchitis and frequent COPD exacerbations. Use of roflumilast as adjunctive or alternate therapy to other COPD medications reduces exacerbations and modestly improves lung function.

AREAS COVERED

This article reviews the current role of PDE4I in COPD treatment emphasizing roflumilast's clinical efficacy and adverse effects. This article also reviews developing PDE4Is in early clinical trials and in preclinical studies.

EXPERT OPINION

After decades of research in drug development, PDE4Is are a welcomed addition to the COPD therapeutic armamentarium. In its current clinical role, the salubrious clinical effects of PDE4I in reducing exacerbations and stabilizing the frequent exacerbator phenotype have to be cautiously balanced with numerous adverse effects. Developing drugs may provide similar or better clinical benefits while minimizing adverse effects by changing the mode of drug delivery to inhaled formulations, combining dual PDE isoenzyme inhibitors (PDE1/4I and PDE3/4I) and by forming hybrid molecules with other bronchodilators (muscarinic receptor antagonist/PDE4I and β2-agonist/PDE4I).

Therapeutic potential of Panax ginseng and ginsenosides in the treatment of chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a major global health burden and will become the third largest cause of death in the world by 2030. It is currently believed that an exaggerated inflammatory response to inhaled irritants, in particular cigarette smoke, cause progressive airflow limitation. This inflammation, where macrophages, neutrophils and lymphocytes are prominent, leads to oxidative stress, emphysema, airways fibrosis and mucus hypersecretion. COPD responds poorly to current anti-inflammatory treatments including corticosteroids, which produce little or no benefit. Panax ginseng has a long history of use in Chinese medicine for respiratory conditions, including asthma and COPD.

OBJECTIVES

In this perspective we consider the therapeutic potential of Panax ginseng for the treatment of COPD.

RESULTS

Panax ginseng and its compounds, ginsenosides, have reported effects through multiple mechanisms but primarily have anti-inflammatory and anti-oxidative effects. Ginsenosides are functional ligands of glucocorticoid receptors and appear to inhibit kinase phosphorylation including MAPK and ERK1/2, NF-κB transcription factor induction/translocation, and DNA binding. They also inhibit pro-inflammatory mediators, TNF-α, IL-6, IL-8, ROS, and proteases such as MMP-9. Panax ginseng protects against oxidative stress by increasing anti-oxidative enzymes and reducing the production of oxidants.

CONCLUSION

Given that Panax ginseng and ginsenosides appear to inhibit processes related to COPD pathogenesis, they represent an attractive therapeutic target for the treatment of COPD.

Clinical application of expectorant therapy in chronic inflammatory airway diseases (Review)

Airway mucus hypersecretion is a significant clinical and pathological feature of chronic inflammatory airway diseases. Its clinical presentations include recurrent coughing and phlegm. Airway mucus is closely associated with the occurrence, development and prognosis of chronic inflammatory airway diseases and critically affects the lung function, quality of life, hospitalization rate and mortality of patients with chronic inflammatory airway diseases. Therefore, expectorant therapies targeting the potential mechanisms of mucus hypersecretion have been the focus of numerous studies. Conventional expectorants are mainly mucoactive medicines, including nausea-stimulating expectorants, mucolytics, mucokinetics, and proteases and nucleases. In addition, certain traditional Chinese herbal medicines and non-mucoactive agents, including muscarinic acetylcholine receptor antagonists, corticosteroids, leukotriene receptor antagonists and macrolide antibiotics, have also shown expectorant effects. Several novel medicines for expectorant therapy have emerged, including cholesterol-lowering statins, epidermal growth factor receptor tyrosine kinase inhibitors, phosphodiesterase-4 inhibitors, stanozolol, surfactants, flavonoids, tachykinin receptor antagonists, protease inhibitors, cytokine antagonists and purinergic agonists. With the increasing number of multidisciplinary studies, the effectiveness of expectorant therapy for the treatment of chronic inflammatory airway diseases has been confirmed. Therefore, the development of novel expectorants and the standardization of expectorant therapy are the direction and focus of future studies, thus benefiting patients who have a chronic inflammatory airway disease.

Phosphodiesterase 4 inhibitors for chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is associated with cough, sputum production or dyspnoea and a reduction in lung function, quality of life and life expectancy. Apart from smoking cessation, there are no other treatments that slow lung function decline. Roflumilast and cilomilast are oral phosphodiesterase 4 (PDE4) inhibitors proposed to reduce the airway inflammation and bronchoconstriction seen in COPD.

OBJECTIVES

To evaluate the efficacy and safety of oral PDE4 inhibitors in the management of stable COPD.

SEARCH METHODS

We identified randomised controlled trials (RCTs) from the Cochrane Airways Group Specialised Register of trials (date of last search June 2013). We found other trials from web-based clinical trial registers.

SELECTION CRITERIA

We included RCTs if they compared oral PDE4 inhibitors with placebo in people with COPD. We allowed co-administration of standard COPD therapy.

DATA COLLECTION AND ANALYSIS

One review author extracted data and a second review author checked the data, before entry into The Cochrane Collaboration software program (RevMan version 5.2). We reported pooled data as mean differences (MD), standardised mean differences (SMD) or odds ratios (OR).

MAIN RESULTS

Twenty-nine separate RCTs studying roflumilast (15 trials, 12,654 patients) or cilomilast (14 trials, 6457 patients) met the inclusion criteria, with a duration between six weeks and one year. These included people across international study centres with moderate to very severe COPD (GOLD grades II-IV), with a mean age of 64 years.Treatment with a PDE4 inhibitor was associated with a significant improvement in forced expiratory volume in one second (FEV1) over the trial period compared with placebo (MD 45.60 mL; 95% confidence interval (CI) 39.45 to 51.75, 22 trials with 15,670 participants, moderate quality evidence due to moderate levels of heterogeneity and risk of reporting bias). There were small improvements in quality of life (St George's Respiratory Questionnaire MD -1.04; 95% CI -1.66 to -0.41, 10 trials with 7618 participants, moderate quality evidence due to moderate levels of heterogeneity and risk of reporting bias) and COPD-related symptoms, but no change in exercise tolerance. Treatment with a PDE4 inhibitor was associated with a reduced likelihood of COPD exacerbation (OR 0.77; 95% CI 0.71 to 0.83, high quality evidence). For every 100 people treated with PDE4 inhibitors, six more remained exacerbation-free during the study period compared with placebo (number needed to treat for an additional beneficial effect (NNTB) 20; 95% CI 16 to 27). More participants in the treatment groups experienced non-serious adverse events compared with controls, particularly gastrointestinal symptoms and headache. Roflumilast in particular was associated with weight loss during the trial period and an increase in insomnia and depressive mood symptoms. Participants treated with PDE4 inhibitors were also more likely to withdraw from the trials because of adverse effects; on average 24% in the treatment groups withdrew compared with 19% in the control groups.

AUTHORS' CONCLUSIONS

In people with COPD, PDE4 inhibitors offered benefit over placebo in improving lung function and reducing the likelihood of exacerbations; however, they had little impact on quality of life or symptoms. Gastrointestinal adverse effects and weight loss were common, and safety data submitted to the US Food and Drug Administration (FDA) have raised concerns over psychiatric adverse events with roflumilast. The optimum place of PDE4 inhibitors in COPD management therefore remains to be defined. Longer-term trials are needed to determine whether or not PDE4 inhibitors modify FEV1 decline, hospitalisation or mortality in COPD.

Does roflumilast improve dyspnea in patients with chronic obstructive pulmonary disease? A meta-analysis

INTRODUCTION

Although several large studies showed roflumilast (Rof) has demonstrated efficacy in patients with chronic obstructive pulmonary disease (COPD), the efficacy of Rof in dyspnea remains unclear. We therefore undertook a meta-analysis to assess the efficacy of Rof in dyspnea for COPD patients.

METHODS

A computerized search through electronic databases was performed to obtain randomized controlled trials (RCTs). Dyspnea was assessed by the transition dyspnea index (TDI) and the UCSD Shortness of Breath Questionnaire (SOBQ). The quality of the included studies was assessed by the Jadad score. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were calculated and heterogeneity was assessed with the I(2) test. The effect sizes were compared with the minimum clinically important difference (MCID).

RESULTS

Four RCTs involving 4,767 patients with forced expiratory volume in one second (FEV1) <80% predicted met the inclusion criteria. The Jadad score of each study was 5 scores. Rof statistically improved the TDI focal score (WMD =0.30 units; 95% CI: 0.14-0.46), but failed to decrease the SOBQ (WMD =-1.10 units; 95% CI: -4.24 to 2.04). The overall effect sizes were lower than the MCID of the TDI and the SOBQ, respectively.

CONCLUSIONS

Sufficient evidence to support Rof relieving dyspnea in COPD patients is currently lacking. Further studies are needed to investigate the effects of Rof in dyspnea, especially for COPD patients with a different phenotype.

Pharmacological approaches to regulate neutrophil activity

Although indispensable in host defense against microbial pathogens, misdirected hyperacute and chronic activation of neutrophils presents the potential hazard of tissue damage, organ dysfunction, and carcinogenesis. In many clinical settings, particularly inflammatory disorders of the airways, over-reactivity of neutrophils is exacerbated by their relative resistance to conventional, pharmacological anti-inflammatory therapies, including, but not limited to, corticosteroids. Notwithstanding their sheer numbers, which can increase rapidly and dramatically during inflammatory responses, these cells are not only pre-programmed to release reactive oxygen species, proteinases, and eicosanoids/prostanoids immediately on exposure to pro-inflammatory stimuli but may also subsequently undergo the process of netosis, thereby enhancing and protracting their inflammatory potential. All of these mechanisms are likely to underpin the resistance of neutrophils to pharmacological control and have triggered the search for alternatives to corticosteroids. In addition to macrolides and adenosine 3',5'-cyclic adenosine monophospate-elevating agents, more recent innovations in the control of neutrophilic inflammation include activators of histone deacetylases and antagonists of chemokine receptors, as well as monoclonal antibodies which target neutrophil-activating cytokines and their receptors. These and other neutrophil-targeted strategies represent the focus of the current review.

Hybrids consisting of the pharmacophores of salmeterol and roflumilast or phthalazinone: dual β₂-adrenoceptor agonists-PDE4 inhibitors for the treatment of COPD

A novel class of dual pharmacology bronchodilators targeting both β(2)-adrenoceptor and PDE4 was designed and synthesised by combining the pharmacophores of salmeterol and roflumilast or phthalazinone. All the compounds exhibited better β(2)-adrenoceptor agonist activities (pEC(50)=8.47-9.20) than the reference compound salmeterol (pEC(50)=8.3) and good inhibitory activity on PDE4B2 (IC(50)=0.235-1.093 μM).

Chronic obstructive pulmonary disease: patho-physiology, current methods of treatment and the potential for simvastatin in disease management

INTRODUCTION

Chronic Obstructive Pulmonary Disease (COPD) is a severe disease that leads to a non-reversible obstruction of the small airways. The prevalence of this disease is rapidly increasing in developed countries, and in 2020 it has been predicted that this disease will reach the third cause of mortality worldwide. COPD patients do not respond well to current treatment modalities, such as bronchodilators and corticosteroids.

AREAS COVERED

This review article focuses on the patho-physiology of COPD, explores current approaches to alleviate and treat the disease, and discusses the potential use of statins for treatment. Specifically, the mechanism of action and metabolism of simvastatin, the most known and studied molecule among the statin family, are critically reviewed.

EXPERT OPINION

Various cellular pathways have been implicated in COPD, with alveolar macrophages emerging as pivotal inflammatory mediators in the COPD patho-physiology. Recently, emerging anti-cytokine therapies, such as PDE4 inhibitors and ACE inhibitors, have shown good anti-inflammatory properties that can be useful in COPD treatment. Recently, statins as a drug class have gained much interest with respect to COPD management, following studies which show simvastatin to exert effective anti-inflammatory effects, via inhibition of the mevalonic acid cascade in alveolar macrophages.

Phosphodiesterase 4 inhibitors for chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) affects symptoms, lung function, quality of life and life expectancy. Apart from smoking cessation, there are no other treatments that slow lung function decline. Roflumilast and cilomilast are oral phosphodiesterase 4 (PDE(4)) inhibitors proposed to reduce the airway inflammation and bronchoconstriction seen in COPD.

OBJECTIVES

To evaluate the efficacy and safety of PDE(4) inhibitors in the management of people with stable COPD. Outcomes included lung function, quality of life, symptoms, exacerbations and adverse effects.

SEARCH STRATEGY

We identified randomised controlled trials (RCTs) from the Cochrane Airways Group Specialised Register of trials (date of last search 6 August 2010). We found other trials from web-based clinical trial registers.

SELECTION CRITERIA

We included RCTs if they compared oral PDE(4) inhibitors with placebo in people with COPD. We allowed co-administration of standard COPD therapy.

DATA COLLECTION AND ANALYSIS

One review author extracted data and a second review author checked the data, before entry into The Cochrane Collaboration software programme (RevMan version 5.1). We reported pooled data as mean differences (MD), standardised mean differences (SMD), or odds ratios (OR).

MAIN RESULTS

Twenty-three separate RCTs studying roflumilast (nine trials, 9211 patients) or cilomilast (fourteen trials, 6457 patients) met the inclusion criteria. None of the trials exceeded a year in duration.Treatment with a PDE(4) inhibitor was associated with a significant improvement in FEV(1)over the trial period compared with placebo (MD 45.59 mL; 95% confidence interval (CI) 39.15 to 52.03), regardless of COPD severity or concomitant COPD treatment. There were some small improvements in quality of life (St George's Respiratory Questionnaire MD -1.04; 95% CI -1.66 to -0.41) and COPD-related symptoms, but no change in exercise tolerance. Treatment with a PDE(4) inhibitor was associated with a reduced likelihood of COPD exacerbation (OR 0.78; 95% CI 0.72 to 0.85). More participants in the treatment groups experienced non-serious adverse events compared with controls, particularly gastrointestinal symptoms and headache. Roflumilast was associated with weight loss during the trial period.

AUTHORS' CONCLUSIONS

In people with COPD, PDE(4) inhibitors offered benefit over placebo in improving lung function and reducing likelihood of exacerbations, however, they had little impact on quality of life or symptoms. Gastrointestinal adverse effects and weight loss were common. The optimum place of PDE(4) inhibitors in COPD management remains to be defined. Longer-term trials are needed to determine whether or not PDE(4) inhibitors modify FEV(1) decline, healthcare utilisation or mortality in COPD.

Bioactive metabolites from the sponge Suberea sp

Two new brominated compounds, subereaphenol K (2) and 2-(3,5-dibromo-1-ethoxy-4-oxocyclohexa-2,5-dien-1-yl)acetamide (3), together with subereaphenol B (methyl 2-(2,4-dibromo-3,6-dihydroxyphenyl)acetate; 1) with a revised structure, and five dibromotyrosine-derived metabolites, 4-8, were isolated from the sponge Suberea sp. and characterized by 1D- and 2D-NMR spectroscopic and HR-MS spectrometric data. Compounds 1, 2, 6, and 8 exhibited various weak or moderate bioactivities, including antimicrobial and cytotoxic activities. Furthermore, compounds 1 and 2 inhibited human recombinant phosphodiesterase 4 (PDE4) with IC₅₀ values of 2 μM, whereas compounds 6 and 8 were less active.

No dose adjustment on coadministration of the PDE4 inhibitor roflumilast with a weak CYP3A, CYP1A2, and CYP2C19 inhibitor: an investigation using cimetidine

This nonrandomized, fixed-sequence, 2-period crossover study investigated potential pharmacokinetic interactions between the phosphodiesterase 4 inhibitor roflumilast, currently in clinical development for the treatment of chronic obstructive pulmonary disease, and the histamine 2 agonist cimetidine. Participants received roflumilast, 500 µg once daily, on days 1 and 13. Cimetidine, 400 mg twice daily, was administered from days 6 to 16. Pharmacokinetic analysis of roflumilast and its active metabolite roflumilast N-oxide was performed, and the ratio of geometric means for roflumilast alone and concomitantly with steady-state cimetidine was calculated. The effect of cimetidine on the total PDE4 inhibitory activity (tPDE4i; total exposure to roflumilast and roflumilast N-oxide) was also calculated. Coadministration of steady-state cimetidine increased mean tPDE4i of roflumilast and roflumilast N-oxide by about 47%. The maximum plasma concentration (C(max)) of roflumilast increased by about 46%, with no effect on C(max) of roflumilast N-oxide. The increase in tPDE4i of roflumilast and roflumilast N-oxide following coadministration with cimetidine was mainly due to the inhibitory effect of cimetidine on cytochrome P450 (CYP) isoenzymes CYP1A2, CYP3A, and CYP2C19. These moderate changes indicate that dose adjustment of roflumilast is not required when coadministered with a weak inhibitor of CYP1A2, CYP3A, and CYP2C19, such as cimetidine.

The preclinical pharmacology of roflumilast--a selective, oral phosphodiesterase 4 inhibitor in development for chronic obstructive pulmonary disease

After more than two decades of research into phosphodiesterase 4 (PDE4) inhibitors, roflumilast (3-cyclopropylmethoxy-4-difluoromethoxy-N-[3,5-di-chloropyrid-4-yl]-benzamide) may become the first agent in this class to be approved for patient treatment worldwide. Within the PDE family of 11 known isoenzymes, roflumilast is selective for PDE4, showing balanced selectivity for subtypes A-D, and is of high subnanomolar potency. The active principle of roflumilast in man is its dichloropyridyl N-oxide metabolite, which has similar potency as a PDE4 inhibitor as the parent compound. The long half-life and high potency of this metabolite allows for once-daily, oral administration of a single, 500-microg tablet of roflumilast. The molecular mode of action of roflumilast--PDE4 inhibition and subsequent enhancement of cAMP levels--is well established. To further understand its functional mode of action in chronic obstructive pulmonary disease (COPD), for which roflumilast is being developed, a series of in vitro and in vivo preclinical studies has been performed. COPD is a progressive, devastating condition of the lung associated with an abnormal inflammatory response to noxious particles and gases, particularly tobacco smoke. In addition, according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD), significant extrapulmonary effects, including comorbidities, may add to the severity of the disease in individual patients, and which may be addressed preferentially by orally administered remedies. COPD shows an increasing prevalence and mortality, and its treatment remains a high, unmet medical need. In vivo, roflumilast mitigates key COPD-related disease mechanisms such as tobacco smoke-induced lung inflammation, mucociliary malfunction, lung fibrotic and emphysematous remodelling, oxidative stress, pulmonary vascular remodelling and pulmonary hypertension. In vitro, roflumilast N-oxide has been demonstrated to affect the functions of many cell types, including neutrophils, monocytes/macrophages, CD4+ and CD8+ T-cells, endothelial cells, epithelial cells, smooth muscle cells and fibroblasts. These cellular effects are thought to be responsible for the beneficial effects of roflumilast on the disease mechanisms of COPD, which translate into reduced exacerbations and improved lung function. As a multicomponent disease, COPD requires a broad therapeutic approach that might be achieved by PDE4 inhibition. However, as a PDE4 inhibitor, roflumilast is not a direct bronchodilator. In summary, roflumilast may be the first-in-class PDE4 inhibitor for COPD therapy. In addition to being a non-steroid, anti-inflammatory drug designed to target pulmonary inflammation, the preclinical pharmacology described in this review points to a broad functional mode of action of roflumilast that putatively addresses additional COPD mechanisms. This enables roflumilast to offer effective, oral maintenance treatment for COPD, with an acceptable tolerability profile and the potential to favourably affect the extrapulmonary effects of the disease.

Functionalized pyrazoles and pyrazolo[3,4-d]pyridazinones: Synthesis and evaluation of their phosphodiesterase 4 inhibitory activity

A series of pyrazoles and pyrazolo[3,4-d]pyridazinones were synthesized and evaluated for their PDE4 inhibitory activity. All the pyrazoles were found devoid of activity, whereas some of the novel pyrazolo[3,4-d]pyridazinones showed good activity as PDE4 inhibitors. The most potent compounds in this series showed an IC(50) in the nanomolar range. The ability to inhibit TNF-alpha release in human PBMCs was determined for two representative compounds, finding values in the sub-micromolar range. SARs studies demonstrated that the best arranged groups around the heterocyclic core are 2-chloro-, 2-methyl- and 3-nitrophenyl at position 2, an ethyl ester at position 4 and a small alkyl group at position 6. Molecular modeling studies performed on a representative compound allowed to define its binding mode to the PDE4B isoform.

The identification of a novel phosphodiesterase 4 inhibitor, 1-ethyl-5-{5-[(4-methyl-1-piperazinyl)methyl]-1,3,4-oxadiazol-2-yl}-N-(tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[3,4-b]pyridin-4-amine (EPPA-1), with improved therapeutic index using pica feeding in rats as a measure of emetogenicity

Clinical utility of phosphodiesterase 4 (PDE4) inhibitors as anti-inflammatory agents has, to date, been limited by adverse effects including nausea and emesis, making accurate assessment of emetic versus anti-inflammatory potencies critical to the development of inhibitors with improved therapeutic indices. In the present study we determined the in vitro and in vivo anti-inflammatory potencies of the first-generation PDE4 inhibitor, rolipram, the second-generation inhibitors, roflumilast and cilomilast, and a novel third generation inhibitor, 1-ethyl-5-{5-[(4-methyl-1-piperazinyl)methyl]-1,3,4-oxadiazol-2-yl}-N-(tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[3,4-b]pyridin-4-amine (EPPA-1). The rank-order potency against lipopolysaccharide (LPS)-induced tumor necrosis factor-alpha production by human peripheral blood mononuclear cells was roflumilast (IC(50) = 5 nM) > EPPA-1 (38) > rolipram (269) > cilomilast (389), and against LPS-induced pulmonary neutrophilia in the rat was EPPA-1 (D(50) = 0.042 mg/kg) > roflumilast (0.24) > rolipram (3.34) > cilomilast (4.54). Pica, the consumption of non-nutritive substances in response to gastrointestinal stress, was used as a surrogate measure for emesis, giving a rank-order potency of rolipram (D(50) = 0.495 mg/kg) > roflumilast (1.6) > cilomilast (6.4) > EPPA-1 (24.3). The low and high emetogenic activities of EPPA-1 and rolipram, respectively, detected in the pica model were confirmed in a second surrogate model of emesis, reversal of alpha(2)-adrenoceptor-mediated anesthesia in the mouse. The rank order of therapeutic indices derived in the rat [(pica D(50))/(neutrophilia D(50))] was EPPA-1 (578) > roflumilast (6.4) > cilomilast (1.4) > rolipram (0.15), consistent with the rank order derived in the ferret [(emesis D(50))/(neutrophilia D(50))]. These data validate rat pica feeding as a surrogate for PDE4 inhibitor-induced emesis in higher species, and identify EPPA-1 as a novel PDE4 inhibitor with an improved therapeutic index.

Production and characterization of pharmacologically active recombinant human phosphodiesterase 4B in Dictyostelium discoideum

Phosphodiesterase 4B (PDE4B) is an important therapeutic target for asthma and chronic obstructive pulmonary disease. To identify PDE4 subtype-specific compounds using high-throughput assays, full-length recombinant PDE4 proteins are needed in bulk quantity. In the present study, full-length human PDE4B2 was expressed in the cellular slime mould Dictyostelium discoideum (Dd). A cell density of 2 x 10(7) cells/mL was obtained and up to 1 mg/L recombinant PDE4B2 was purified through Ni-NTA affinity chromatography. The expressed protein was soluble and its activity was comparable to PDE4B2 protein expressed in mammalian cells (K(m)=1.7 microM). The functional significance of the Dd expression system is supported by the demonstration that, in concert with proteins expressed in mammalian systems, there are no major changes in the affinity for PDE4B2 inhibitors and substrates. These findings thus provide the first evidence that Dd can be utilized for the expression and purification of functionally active full-length human PDE4B2 in large amounts required for high-throughput screening of pharmacologically active compounds against this therapeutic target.

Phosphodiesterase 4 inhibitors in chronic obstructive pulmonary disease: a new approach to oral treatment

Chronic obstructive pulmonary disease represents a major global health care burden for both primary and secondary care providers and is the most common respiratory condition necessitating hospital admission. Short-acting bronchodilators play a vital role in immediate relief of symptoms, while inhaled long-acting bronchodilators and inhaled corticosteroids are advocated for regular use in individuals with persistent symptoms and exacerbations. Theophylline is a nonspecific phosphodiesterase inhibitor and is usually reserved for patients with ongoing symptoms despite optimum inhaled bronchodilator treatment or when difficulty is encountered with inhaler devices. However, it is often not widely used mainly due to frequency of dose-related adverse effects, numerous drug interactions and narrow therapeutic index. This in turn has lead to the development of more selective phosphodiesterase inhibitors in an attempt to create a drug which patients can use with beneficial effects but without the problems associated with theophylline. Current data do indicate that phosphodiesterase 4 inhibitors confer some benefits in chronic obstructive pulmonary disease when compared to placebo in terms of lung function, quality of life and exacerbations. They are also generally well tolerated. Further studies are required to determine fully their long-term beneficial and adverse effect profiles and ultimately where they might comfortably sit in management algorithms.

MK-0873, a PDE4 inhibitor, does not influence the pharmacokinetics of theophylline in healthy male volunteers

BACKGROUND

MK-0873 is a novel selective phosphodiesterase-4 inhibitor, which has been in development for the treatment of chronic obstructive pulmonary disease (COPD). In this indication, theophylline is still an important treatment, despite its relatively small therapeutic window. In view of this, it is important to investigate whether MK-0873 could affect the pharmacokinetics, safety and tolerability of theophylline, when both drugs are given concomitantly.

AIM

The objective of this study was to investigate the effect of multiple doses of oral MK-0873, a selective phosphodiesterase-4 inhibitor, on the pharmacokinetics, safety and tolerability profile of orally administered theophylline in healthy volunteers.

METHODS

Eight healthy, non-smoking male subjects participated in this randomized, open-label, 2-period, cross-over study. In one period subjects received an oral dose of 2.5mg MK-0873 for 6 days co-administered with a single oral dose of 250 mg theophylline on day 5. The other period consisted of a single dose of 250 mg theophylline on day 1. In each period, blood samples were collected at predefined time points to evaluate theophylline pharmacokinetics.

RESULTS

All subjects completed the study. The study medications were generally well tolerated and no clinically relevant changes were observed in either treatment periods. No significant difference was found in the AUC 0-infinity (77.7 vs. 83.8h ng/ml; p=0.280) and Cmax (6.70 vs. 7.77 ng/ml; p=0.125) of theophylline between the MK-0873+theophylline and theophylline only treatment, and bioequivalence was demonstrated for AUC0-infinity (geometric mean ratio with 90% confidence interval: 0.930 (0.826, 1.047)).

CONCLUSION

In this study, in a limited number of subjects, co-administration of oral MK-0873 did not affect the pharmacokinetics, safety, and tolerability of oral theophylline in non-smoking healthy male subjects.

Cloning, stable expression of human phosphodiesterase 7A and development of an assay for screening of PDE7 selective inhibitors

Phosphodiesterases (PDEs) constitute a superfamily of enzymes that plays an important role in signal transduction by catalysing the hydrolysis of cAMP and cGMP. cDNA encoding PDE7A1 subtype was cloned and a stable recombinant HEK 293 cell line expressing high levels of PDE7A1 was generated. Transient transfection of pCRE-Luc plasmid, harboring luciferase reporter gene into the stable recombinant cell line and subsequent treatment with PDE7 inhibitor, resulted in a dose-dependent increase in luciferase activity. This method provides a simple and sensitive cell-based assay for screening of PDE7 selective inhibitors for the treatment of T cell mediated diseases.

Effect of theophylline on the rate of moderate to severe exacerbations among patients with chronic obstructive pulmonary disease

AIM

To determine the effectiveness of theophyllines in real clinical practice on moderate to severe exacerbations.

METHODS

A cohort of 36,492 chronic obstructive pulmonary disease (COPD) patients aged > or =50 years was reconstructed from the health administrative databases of the province of Quebec, Canada, between 1 January 1995 and 31 December 2002 to compare users of theophyllines with users of inhaled corticosteroids (ICS) and users of long-acting beta(2)-agonists (LABA) on their rate of moderate to severe COPD exacerbations.

RESULTS

Users of theophyllines were found to be less likely than users of LABA [crude rates 84 vs. 91 per 100 patient-years, adjusted rate ratio (RR) 0.89, 95% confidence interval (CI) 0.84, 0.95] and users of theophyllines plus ICS were found to be less likely than users of LABA plus ICS (crude rates 114 vs. 112 per 100 patient-years, adjusted RR 0.89, 95% CI 0.87, 0.92) to have moderate to severe COPD exacerbations. Users of theophyllines were found to be more likely than users of ICS to have a COPD exacerbation (crude rates 84 vs. 77 per 100 patient-years, adjusted RR 1.07, 95% CI 1.04, 1.10), and this association was even stronger among patients who had at least three exacerbations in the year prior to cohort entry (crude rates 273 vs. 213 per 100 patient-years, adjusted RR 1.28, 95% CI 1.19, 1.38).

CONCLUSION

The use of theophyllines was found to be associated with a reduction in the rate of COPD exacerbations among all COPD patients, but to be less effective than ICS among patients with frequent exacerbations.

Roflumilast inhibits leukocyte-endothelial cell interactions, expression of adhesion molecules and microvascular permeability

BACKGROUND AND PURPOSE

The present study addressed the effects of the investigational PDE4 inhibitor roflumilast on leukocyte-endothelial cell interactions and endothelial permeability in vivo and in vitro.

EXPERIMENTAL APPROACH

In vivo, intravital video-microscopy was used to determine effects of roflumilast p.o. on leukocyte-endothelial cell interactions and microvascular permeability in rat mesenteric venules. In vitro, the effects of roflumilast N-oxide, the active metabolite of roflumilast in humans, and other PDE4 inhibitors on neutrophil adhesion to tumour necrosis factor alpha (TNFalpha)-activated human umbilical vein endothelial cells (HUVEC), E-selectin expression and thrombin-induced endothelial permeability was evaluated. Flow cytometry was used to determine the effect of roflumilast on N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced CD11b upregulation on human neutrophils.

KEY RESULTS

In vivo, roflumilast, given 1 h before lipopolysaccharide (LPS), dose-dependently reduced leukocyte-endothelial cell interactions in rat mesenteric postcapillary venules. It also diminished histamine-induced microvascular permeability. Immunohistochemical analyses revealed that roflumilast prevented LPS-induced endothelial P- and E-selectin expression. In vitro, roflumilast N-oxide concentration-dependently suppressed neutrophil adhesion to TNFalpha-activated HUVEC and CD11b expression on fMLP-stimulated neutrophils. It also reduced TNFalpha-induced E-selectin expression on HUVEC, when PDE3 activity was blocked. HUVEC permeability elicited by thrombin was concentration-dependently suppressed by roflumilast N-oxide. While roflumilast N-oxide was as potent as roflumilast at inhibiting stimulated endothelial cell and neutrophil functions, both compounds were significantly more potent than the structurally unrelated PDE4 inhibitors, rolipram or cilomilast.

CONCLUSIONS AND IMPLICATIONS

These findings further support earlier observations on the inhibition of inflammatory cell influx and protein extravasation by roflumilast in vivo.

Phosphodiesterases regulate airway smooth muscle function in health and disease

On the basis of structure, regulation, and kinetic properties, phosphodiesterases (PDEs) represent a superfamily of enzymes divided into 11 subfamilies that catalyze cytosolic levels of 3',5'-cyclic adenosine monophosphate (cAMP) or 3',5'-cyclic guanosine monophosphate (cGMP) to 5'-AMP or 5'-GMP, respectively. PDE4 represents the major PDE expressed in inflammatory cells as well as airway smooth muscle (ASM), and selective PDE4 inhibitors provide a broad spectrum of anti-inflammatory effects such as abrogating cytokine and chemokine release from inflammatory cells and inhibiting inflammatory cell trafficking. Due to cell- and tissue-specific gene expression and regulation, PDEs modulate unique organ-based functions. New tools or compounds that selectively inhibit PDE subfamilies and genetically engineered mice deficient in selective isoforms have greatly enhanced our understanding of PDE function in airway inflammation and resident cell function. This chapter will focus on recent advances in our understanding of the role of PDE in regulating ASM function.

Targeting the phosphatidylinositol 3-kinase pathway in airway smooth muscle: rationale and promise

The phosphatidylinositol 3-kinase (PI3K) signaling pathway plays a critical role in regulating cell growth, proliferation, survival, and motility. Structural alterations, e.g. airway remodeling, in asthma and chronic obstructive pulmonary disease (COPD) are associated with increased airway smooth muscle (ASM) cell growth and proliferation due to the frequent stimulation of ASM by inflammatory mediators, contractile agonists, and growth factors. The critical role of the PI3K signaling pathway in regulating ASM cell growth and proliferation is well established. However, recent discovery of the tumor suppressor proteins tuberous sclerosis complex 1 (TSC1) and TSC2, also known as hamartin and tuberin, as downstream effectors of PI3K and upstream regulators of the mammalian target of rapamycin (mTOR) and S6 kinase 1(S6K1) shed a new light on the PI3K signaling cascade in regulating cell growth and proliferation. The activity of TSC1/TSC2 is regulated by growth factors, nutrients, and energy; thus, TSC1/TSC2 serves as a signaling module for protein translational regulation, cell cycle progression, and cell size, which are key events controlling cell growth and proliferation. This article highlights the potential contribution of the PI3K-TSC1/TSC2-mTOR/S6K1 pathway in smooth muscle remodeling. Pharmacologic manipulation of this signaling pathway could have a major impact on treatment of asthma and COPD.

One hundred years of chronic obstructive pulmonary disease (COPD)

Chronic obstructive pulmonary disease (COPD) is an increasing health problem and one of the leading causes of morbidity and mortality worldwide, but knowledge about its pathogenesis has increased substantially in recent years. The disease results from interaction between individual risk factors (like enzymatic deficiencies) and environmental exposures to noxious agents, like cigarette smoking, occupational dusts, air pollution and infections in childhood. The main mechanisms that may contribute to airflow limitation in COPD are fixed narrowing of small airways, emphysema and luminal obstruction with mucus secretions. COPD is characterised by a chronic inflammatory process in the pulmonary tissue, with a pattern different from bronchial asthma, associated with extrapulmonary effects and is considered now a complex, systemic disease. Optimal therapeutic targeting of COPD depends on a clear understanding of the precise mechanisms of these complex processes and on early and correct evaluation of disease severity. A combination of pharmacological and non-pharmacological approaches is used to treat COPD. Bronchodilators are the mainstay of COPD treatment and can be combined with inhaled corticosteroids for greater efficacy and fewer side effects. The use of LTOT for hypoxemic patients has resulted in increased survival, and expanded drug therapy options have effectively improved dyspnoea and quality of life. Recent studies have documented the benefits of pulmonary rehabilitation. In addition, non-invasive mechanical ventilation offers new alternatives for patients with acute or chronic failure.

A reporter gene assay for screening of PDE4 subtype selective inhibitors

Phosphodiesterase (PDE) constitutes a superfamily of enzymes that catalyze the hydrolysis of cAMP and cGMP into their corresponding monophosphates and play an important role in diverse physiological functions. The present study provides a process for identifying PDE4 subtypes selective inhibitors using a reporter gene assay. Stable recombinant HEK-293 cell lines expressing high levels of PDE4A4B, PDE4B2A, and PDE4D3 subtypes individually were generated. Transient transfection of pCRE-Luc plasmid, harboring luciferase reporter gene under the control of cAMP response element (CRE)-binding sequence, into these stable recombinant cell lines followed by treatment with PDE4 inhibitor, resulted in a dose dependent increase in luciferase activity. This methods provide a novel, simple and sensitive assay for high throughput screening of PDE4 subtype selective inhibitors for treatment of asthma and COPD.