Future Advances in COPD Therapy

Attenuation of inflammatory mediator production by the NF-κB member RelB is mediated by microRNA-146a in lung fibroblasts

Lung inflammation can result from exposure to multiple types of inflammatory stimuli. Fibroblasts, key structural cells in the lung that are integral to inflammation and wound healing, produce inflammatory mediators after exposure to stimuli such as IL-1β. We and others have shown that the NF-κB member RelB has anti-inflammatory properties in mice. Little is known, however, about the anti-inflammatory role of RelB in human cells and how it functions. MicroRNAs (miRNAs), a novel class of small, noncoding RNAs, can mediate inflammatory signaling pathways, including NF-κB, through regulation of target gene expression. Our goal was to analyze the anti-inflammatory properties of RelB in human lung fibroblasts. We hypothesized that RelB regulates inflammatory mediator production in lung fibroblasts in part through a mechanism involving miRNAs. To accomplish this, we transfected human lung fibroblasts with a plasmid encoding RelB and small interfering (si)RNA targeting RelB mRNA to overexpress and downregulate RelB, respectively. IL-1β, a powerful proinflammatory stimulus, was used to induce NF-κB-driven inflammatory responses. RelB overexpression reduced IL-1β-induced cyclooxygenase (Cox)-2, PGE₂, and cytokine production, and RelB downregulation increased Cox-2 expression and PGE₂ production. Furthermore, RelB overexpression increased IL-1β-induced expression of miRNA-146a, an NF-κB-dependent miRNA with anti-inflammatory properties, whereas RelB downregulation reduced miRNA-146a. miR-146a overexpression ablated the effects of RelB downregulation on IL-1β-induced Cox-2, PGE₂, and IL-6 production, suggesting that RelB mediates IL-1β-induced inflammatory mediator production in lung fibroblasts through miRNA-146a. RelB and miRNA-146a may therefore be new therapeutic targets in the treatment of lung inflammation caused by various agents and conditions.

Electrophilic PPARγ Ligands Attenuate IL-1β and Silica-Induced Inflammatory Mediator Production in Human Lung Fibroblasts via a PPARγ-Independent Mechanism

Acute and chronic lung inflammation is associated with numerous important disease pathologies including asthma, chronic obstructive pulmonary disease and silicosis. Lung fibroblasts are a novel and important target of anti-inflammatory therapy, as they orchestrate, respond to, and amplify inflammatory cascades and are the key cell in the pathogenesis of lung fibrosis. Peroxisome proliferator-activated receptor gamma (PPARγ) ligands are small molecules that induce anti-inflammatory responses in a variety of tissues. Here, we report for the first time that PPARγ ligands have potent anti-inflammatory effects on human lung fibroblasts. 2-cyano-3, 12-dioxoolean-1, 9-dien-28-oic acid (CDDO) and 15-deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂) inhibit production of the inflammatory mediators interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), COX-2, and prostaglandin (PG)E₂ in primary human lung fibroblasts stimulated with either IL-1β or silica. The anti-inflammatory properties of these molecules are not blocked by the PPARγ antagonist GW9662 and thus are largely PPARγ independent. However, they are dependent on the presence of an electrophilic carbon. CDDO and 15d-PGJ₂, but not rosiglitazone, inhibited NF-κB activity. These results demonstrate that CDDO and 15d-PGJ₂ are potent attenuators of proinflammatory responses in lung fibroblasts and suggest that these molecules should be explored as the basis for novel, targeted anti-inflammatory therapies in the lung and other organs.

Lung-targeted overexpression of the NF-κB member RelB inhibits cigarette smoke-induced inflammation

Acute lung inflammation can be caused by a variety of respirable agents, including cigarette smoke. Long-term cigarette smoke exposure can cause chronic obstructive pulmonary disease (COPD), a serious illness that affects >10 million Americans. Cigarette smoke is a known inducer of inflammation and is responsible for approximately 90% of all COPD cases. RelB, a member of the NF-κB family, attenuates cigarette smoke-induced inflammatory mediator production in mouse lung fibroblasts in vitro. We hypothesized that overexpression of RelB in the airways of mice would dampen acute smoke-induced pulmonary inflammation. Mice received a recombinant adenovirus encoding RelB by intranasal aspiration to induce transient RelB overexpression in the lungs and were subsequently exposed to mainstream cigarette smoke. Markers of inflammation were analyzed after smoke exposure. Neutrophil infiltration, normally increased by smoke exposure, was significantly and potently decreased after RelB overexpression. Cigarette smoke-induced proinflammatory cytokine and chemokine production, cyclooxygenase-2 expression, and prostaglandin E(2) production were also significantly decreased in the context of RelB overexpression. The expression of intercellular adhesion molecule 1, an NF-κB-dependent protein, was decreased, indicating a potential mechanism through which RelB can regulate inflammatory cell migration. Therefore, increased expression and/or activation of RelB could be a novel therapeutic strategy against acute lung inflammation caused by respirable agents and possibly against chronic injury, such as COPD.

Discovery of novel and potent aryl diamines as leukotriene A4 hydrolase inhibitors

The synthesis and biological evaluation of a series of aryl diamines as inhibitors of LTA(4)-h inhibitors are described. The optimization which led to the identification of the optimal para-substitution on the diphenyl ether moiety and diamine spacer is discussed. The resulting compounds such as 3l have excellent enzyme and cellular potency as well as desirable pharmacokinetic properties.

Synthesis of N-alkyl glycine amides as potent inhibitors of leukotriene A4 hydrolase

The synthesis and biological evaluation of a series of N-alkyl glycine amide analogs as LTA(4)-h inhibitors and the importance of the introduction of a benzoic acid group to the potency and pharmacokinetic parameters of our analogs are described. The lead compound in the series, 4q, has excellent potency and oral bioavailability.

Synthesis of glutamic acid analogs as potent inhibitors of leukotriene A4 hydrolase

Leukotriene B(4) (LTB(4)) is a potent pro-inflammatory mediator that has been implicated in the pathogenesis of multiple diseases, including psoriasis, inflammatory bowel disease, multiple sclerosis and asthma. As a method to decrease the level of LTB(4) and possibly identify novel treatments, inhibitors of the LTB(4) biosynthetic enzyme, leukotriene A(4) hydrolase (LTA(4)-h), have been explored. Here we describe the discovery of a potent inhibitor of LTA(4)-h, arylamide of glutamic acid 4f, starting from the corresponding glycinamide 2. Analogs of 4f are then described, focusing on compounds that are both active and stable in whole blood. This effort culminated in the identification of amino alcohol 12a and amino ester 6b which meet these criteria.

Drugs in clinical development for chronic obstructive pulmonary disease

Many drugs may be potentially useful in the treatment of chronic obstructive pulmonary disease (COPD), but relatively few become available for human use due to lack of safety, lack of efficacy, or both. This is an inherent risk in the drug development process, which coupled with the limited understanding of the molecular pathogenesis of COPD, has produced a trend toward improving existing compounds rather than to develop new compounds. This review focuses on improved existing compounds and newly discovered compounds that are in clinical trials, but not yet marketed. The improved existing compounds include: isomers of the long-acting bronchodilators, once-daily beta2-adrenoceptor agonists, anticholinergics and corticosteroids. The pool of novel compounds is in constant fluctuation and comprises anti-inflammatory drugs, antioxidants, leukotriene modifiers and a number of compounds aimed at treating different aspects of COPD such as pulmonary hypertension and hypophosphatemia.

COPD, a multicomponent disease: implications for management

Chronic obstructive pulmonary disease (COPD) is a multicomponent disease. These components affect both the lungs and organs outside the lungs (the so-called systemic effects of COPD) and can be of either a structural (including airway remodelling, emphysema, skeletal muscle wasting) or functional nature (inflammation, apoptosis, senescence). Further, these components are interdependent in a closely linked 'vicious cycle'. Accordingly, optimal therapies should therefore aim to address more than one of these components to break such a cycle. This needs to be considered not only in the development of future treatments but also in the current clinical management of patients with COPD. In this paper, evidence that supports the concept that COPD is a multicomponent disease is presented. The effects of currently available therapeutic options, including long-acting anticholinergics and long-acting beta2-agonist/inhaled corticosteroid combination therapies, upon each of these components is reviewed. In addition, potential new avenues for drug development and improved patient care are highlighted. By developing a better understanding of how different therapies impact upon the 'vicious cycle' of COPD, treatment regimens can be optimised to provide the greatest benefits to patients.

Association of vitamin D binding protein variants with chronic mucus hypersecretion in Iceland

BACKGROUND

Previous studies of vitamin D binding protein (VDBP, also known as group-specific component, Gc, encoded by the GC gene) have implicated two gene variants, GC*2 and GC*1F, as possible contributors with chronic obstructive pulmonary disease (COPD) protection and susceptibility, respectively. The objective of this study was to examine the association of VDBP to different subtypes of COPD.

STUDY DESIGN

The association of the various GC genotypes to the COPD phenotype was examined in Icelandic COPD patients who were followed by pulmonary physicians at the University Hospital of Iceland.

METHODS

All patients were genotyped for the known alleles of the GC gene. The single nucleotide polymorphisms (SNPs) were identified by a restriction fragment length polymorphism procedure. Study power was estimated based on allele frequencies of the variants, and risk ratios were calculated from the prevalence of genotypes in the affected group divided by its prevalence in the control population. Statistical analyses were performed using the 2-tailed Fisher's Exact Test and chi(2) test, where appropriate.

PATIENT GROUP

One hundred and two COPD patients and 183 controls, together with 46 asthma patients and 48 patients with chronic mucous hypersecretion (CMH) were examined.

MAIN OUTCOME MEASURE AND RESULTS

The results demonstrate similar allele and genotype frequencies of GC in COPD patients overall and healthy controls. However, there was a higher prevalence of genotypes carrying a GC*1F allele and lower prevalence of genotypes with a GC*2 allele in the CMH patients than in controls. This difference was most notable in the homozygous form: 8.3% vs 1.1% for the GC*1F/*1F, and 0.0% vs 7.6% for the GC*2/*2 genotypes, respectively. When controlled for smoking, only the non-smoking CMH patients demonstrated a significantly altered frequency of the GC*1F/*1F genotype (p = 0.0001). The prevalence of the GC*2/*2 genotype was also significantly lower in patients with bronchial hypersecretion with airflow obstruction compared with the control group (2.9% vs 7.6%). Taken together, these results demonstrate that the GC*1F and GC*2 alleles are associated with sputum hypersecretion in individuals who are at increased risk of developing COPD.

Cigarette smoke induces cyclooxygenase-2 and microsomal prostaglandin E2 synthase in human lung fibroblasts: implications for lung inflammation and cancer

Cigarette smoking can lead to many human pathologies including cardiovascular and respiratory disease. Recent studies have defined a role for fibroblasts in the development of colon cancer. Moreover, fibroblasts are now thought of as key "sentinel" cells that initiate inflammation by releasing proinflammatory mediators including prostaglandins (PGs). Pathological overexpression of cyclooxygenase-2 (COX-2) and excess eicosanoid production are found in the early stages of carcinogenesis. By promoting chronic inflammation, COX-2 and eicosanoid production may actually cause a predisposition to malignancy. Furthermore, the associated inflammation induced by production of these mediators is central to the pathogenesis of chronic obstructive pulmonary disease. Little is known of the responses of normal lung fibroblasts to cigarette smoke, despite their abundance. We report herein that normal human lung fibroblasts, when exposed to cigarette smoke extract, induce COX-2 with concurrent synthesis of prostaglandin E2 (PGE2). The mechanisms by which cigarette-derived toxicants lead to increased COX-2 levels and PGE2 synthesis include increases in steady-state COX-2 mRNA levels (approximately four- to fivefold), phosphorylation of ERK1/2, and nuclear translocation of the p50 and p65 subunits of the transcription factor NF-kappaB, which are important elements in COX-2 expression. Furthermore, there was a dramatic 25-fold increase in microsomal prostaglandin E synthase, the key enzyme involved in the production of PGE2. We propose that normal human lung fibroblasts, when exposed to cigarette smoke constituents, elicit COX-2 expression with consequent prostaglandin synthesis, thus creating a proinflammatory environment. This chronic inflammatory state may act as one of the first steps towards epithelial transformation.

Effect of low-dose theophylline on airway inflammation in COPD

OBJECTIVE

Recent studies have shown that theophylline may exert anti-inflammatory effects on neutrophils. We undertook to assess the effect of theophylline on airway inflammation in COPD.

METHODOLOGY

We performed a 4-week randomized double-blind, placebo-controlled study in 11 theophylline-naive patients with mild to moderate COPD. After a 1-week run-in period, six subjects were administered 400 mg/day theophylline (Theodur; Nikken Chemicals Co. Ltd, Tokyo, Japan) for 4 weeks, while five subjects were administered a placebo. Induced sputum was obtained before and after the run-in period and then after 2 and 4 weeks of treatment. Cell differential count and levels of interleukin-8, matrix metalloproteinase-9, neutrophil elastase (NE), myeloperoxidase (MPO), alpha1-antitrypsin (alpha1-AT), leukotriene B4 and tissue inhibitor of metalloproteinases-1 (TIMP-1) were assessed.

RESULTS

No variable was significantly different during the run-in period or with placebo treatment. In contrast, theophylline treatment significantly decreased NE and MPO levels at 4 weeks, although the cell differential count did not change appreciably as a result of treatment.

CONCLUSION

These results suggest that 4 weeks of theophylline treatment attenuates neutrophil-associated inflammation in the airways of mild to moderate COPD patients. However, the clinical benefits remain to be determined.

p38 Mitogen-Activated Protein Kinase Inhibitor Protects the Epidermis Against the Acute Damaging Effects of Ultraviolet Irradiation by Blocking Apoptosis and Inflammatory Responses

The primary function of the epidermis is to provide a protective barrier against numerous environmental insults, including ultraviolet radiation (UVR). UVR, particularly in the UVB spectrum, is a potent carcinogen known to damage DNA directly or through the generation of free radicals. Although in the long term, protective measures such as apoptosis and inflammation may prove beneficial in safeguarding the epidermis against the propagation of potentially tumorigenic cells, after high-dose UV irradiation these biologic events may be acutely detrimental to the architectural and functional integrity of the tissue owing to rampant cell death and inflammatory responses, which can culminate in epidermal erosion and consequently loss of barrier functions. The mitogen-activated protein kinase (MAPK) signaling pathway is known to be activated by UVR and herein we identify p38 MAPK as a key modulator of these physiologic events. Mice treated with the p38 MAPK inhibitor SB202190 are protected against several detrimental effects of acute UV irradiation, namely, sunburn cell/apoptosis, inflammation, and a hyperproliferation response. Based on our results, selectively blocking p38 activation with the SB202190 inhibitor could prove beneficial in treating victims from severe sunburn or exposure to other chemical agents known to trigger the p38 pathway.

Targeting the issues in chronic obstructive lung disease

Chronic obstructive pulmonary disease (COPD) is a disease of unclear aetiology and variable pathology among patients. Little is known about the cellular mechanisms which cause this condition and, although the incidence of COPD has been rising worldwide for some time, research efforts have only very recently increased. Medication thus far has focused on symptom treatment rather than targeting identifiable disease mechanisms. Such treatment has consisted primarily of bronchodilators, both beta-agonists and anticholinergic in action. Treatment with steroids has been disappointing, except in the case of acute exacerbation, and this has shifted the research focus to characterising the inflammatory process in COPD as distinct from that in asthma. New targets for pharmacotherapy are coming to light as information is gained about specific inflammatory mediators active in COPD and the role of oxidative stress in this disease. In addition, new approaches include describing the role of exogenous antiproteases in restoring the balance between protease-antiprotease mechanisms that may be defective in this disease. Ultimately, exploration of the molecular genetics of COPD will provide new targets for future pharmacological agents.

Long-acting inhaled beta 2-agonists for stable COPD

OBJECTIVE

To describe the pathogenesis of chronic obstructive pulmonary disease (COPD) and mechanisms of benefit, formulations available, drug costs, pharmacokinetic profiles, and pertinent clinical studies for long-acting beta(2)-agonists.

DATA SOURCES

A MEDLINE search was conducted from July 1966 through October 2002.

STUDY SELECTION AND DATA EXTRACTION

Pertinent articles related to COPD and long-acting beta(2)-agonists.

DATA SYNTHESIS

The incidence and subsequent morbidity and mortality of COPD have increased during the last 4 decades, prompting worldwide initiatives to formulate guidelines to decrease the burden of this disease. COPD is a progressive, irreversible disease state characterized by chronic cough, dyspnea, sputum production, and wheezing, in which no medication has been shown to decrease mortality, excluding oxygen supplementation. Bronchodilators have been a mainstay of COPD treatment through their ability to work by both smooth- and non-smooth-muscle mechanisms. Long-acting beta(2)-agonists (i.e., formoterol, salmeterol) dosed twice daily provide more convenient dosing than 4-times-daily regimens of traditional short-acting bronchodilators. Both formoterol and salmeterol have acceptable adverse event profiles when used at recommended doses. There have been no direct clinical outcome studies comparing formoterol and salmeterol, but both have shown some benefits over ipratropium and theophylline in improving the symptoms, spirometric indices, exacerbations, and quality of life of patients with COPD.

CONCLUSIONS

Based on current evidence, long-acting beta(2)-agonists are acceptable first-line agents for patients with COPD.

Profile of a Brazilian population with severe chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a public health problem. Tobacco smoking is the major cause, but not the only one. Air pollution, exposure to chemicals, environmental smoke exposure, and passive smoking are among other contributing causes; being viral and bacterial infections also risk factors. Gender and weight are associated to the severity of the disease. Co-morbidity is frequent. OBJECTIVE: To characterize a population of COPD outpatients followed at an outsourced medical service. METHODS: Questionnaires were applied to patients with COPD. The data included gender, age, weight, body mass index (BMI), oxygen delivery users, and FEV1, exposure to tobacco smoke, exposure to wood smoke, history of tuberculosis and co-morbid diseases. RESULTS: Of the 70 patients enrolled in the study, 70% (49) were men with an average age of 64 ± 10 years, average weight of 63 ± 16 kg and average BMI of 22 ± 5 kg/m². Mean FEV1 was 35 ± 14% and 45.7% were oxygen dependent. Nine (12.8%) patients never smoked, while 78.8% had quit tobacco smoking, (38 ± 11 pack/years was the average). Nine (12.8%) smoked corn husk cigarettes. Eighteen (25.7%) were exposed to wood smoke. Eleven (15.7%) patients had tuberculosis, 5.7% complained of asthma symptoms, 2.8% had bronchiectasis, 11.4% diabetes mellitus, 51.4% hypertension, and 20% Cor pulmonale. CONCLUSION: Other possible COPD etiologies must be investigated. Determinants of the pulmonary injury could be environmental smoke exposure associated to former infections. Men with low BMI are typically representative of this severe patient population. Hypertension and Cor Pulmonale are frequent co-morbidity factors.

Cyclooxygenase-2-dependent and thromboxane-dependent vascular and bronchial responses are regulated via p38 mitogen-activated protein kinase in control and endotoxin-primed rat lungs

Mitogen-activated protein kinases (MAPKs) are part of an intracellular signaling machinery consisting of three known distinct pathways, each leading to activation of a different protein kinase: p38, ERK (extracellular signal-regulated kinase), or JNK (c-Jun N-terminal kinase). We investigated the role of the p38 MAPK pathway in the phenomenon of lung endotoxin "priming": incubation of perfused rat lungs with lipopolysaccharide (LPS) for 2 hours results in drastically enhanced cyclooxygenase-2-dependent and thromboxane synthase-dependent vasoconstriction and bronchoconstriction, including edema formation in response to a second inflammatory stimulus, such as arachidonic acid application. Two unrelated selective inhibitors of p38 (SB203580 and SC-68376) dose dependently suppressed the arachidonic acid-induced pulmonary artery pressor response, edema formation, and bronchoconstrictor response in both control lungs and lungs that underwent preceding endotoxin priming. In parallel, thromboxane, but not prostacyclin, released into the lung perfusate was dose dependently inhibited. Using immunohistochemical techniques in combination with quantitative microdensitometry, p38 was detected in nearly all cell types in control lungs, whereas the activated form p-p38 was only expressed in certain cell types, eg, bronchial epithelial cells, endothelial cells, alveolar macrophages, and vascular smooth muscle cells (SMC) of small vessels. In response to endotoxin, p-p38 expression was additionally observed in septal cells, bronchial SMC, and vascular SMC of larger pulmonary vessels and was increased in most other cell types including small-vessel SMC. We conclude that both immunolocalization of p38 activity and pharmacologic interventions support a strong role of the p38 MAPK pathway in establishing an active cyclooxygenase-2/thromboxane synthase axis in vascular and bronchial SMC, with up-regulation of this signaling cascade occurring in LPS priming and being responsible for enhanced pulmonary artery pressor response, edema formation, and bronchoconstriction. Moreover, LPS induces or increases phosphorylation of p38 in other lung cell types. The physiologic consequences of these events remain to be established.

Therapy of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease is one of the commonest causes of morbidity and mortality in the world, and is increasing in prevalence. Current therapies are not very effective, and no current treatment prevents the relentless progression of airflow limitation that characterizes this disease. Smoking cessation is the only strategy that reduces this decline in lung function, and although bupropion is the most effective aid to quitting, more effective treatments of nicotine addiction are needed. The mainstay of treatment is bronchodilators for symptom relief, and inhaled anticholinergics and beta(2)-agonists are useful by reducing hyperinflation of the lungs. A new once-daily inhaled anticholinergic is the most effective bronchodilator, but long-acting inhaled beta(2)-agonists are also useful. Theophylline is used as an additional bronchodilator in more severe patients, and may have some anti-inflammatory action. In contrast, inhaled corticosteroids are poorly effective and do not reduce disease progression, although recent studies with combination inhalers (corticosteroid + long-acting beta(2)-agonist) have shown better effects. Long-term oxygen therapy is needed by patients with pulmonary hypertension and right heart failure. There is a pressing need to develop new classes of therapy, and several new drugs are current in development, including interleukin-8 antagonists, phosphodiesterase-4 inhibitors, protease inhibitors, and antioxidants.

Neutrophil elastase inhibitors as treatment for COPD

Chronic obstructive pulmonary disease, characterised by a slowly progressive, irreversible airways limitation, is a major worldwide cause of chronic morbidity and mortality. The imbalance between human neutrophil elastase and endogenous antiproteases may cause excess human neutrophil elastase in pulmonary tissues, which may be considered a major pathogenic factor in chronic obstructive pulmonary disease. Great effort has been devoted to finding a method to restore the balance, resulting in the discovery of potent two-typed small-molecular-weight human neutrophil elastase inhibitors. In the application of chronic obstructive pulmonary disease therapy, the human neutrophil elastase inhibitors mainly focused upon include ONO-5046, MR-889, L-694,458, CE-1037, GW-311616 and TEI-8362 as the acyl-enzyme inhibitors; and ONO-6818, AE-3763, FK-706, ICI-200,880, ZD-0892 and ZD-8321 as the transition-state inhibitors. In this review, various problems that remain to be solved in the clinical use of human neutrophil elastase inhibitors are discussed.