The safety and efficacy of infliximab in moderate to severe chronic obstructive pulmonary disease

The role of interleukin-1beta in murine cigarette smoke-induced emphysema and small airway remodeling

Interleukin-1beta (IL-1beta), a proinflammatory cytokine, is elevated in cigarette smokers. To determine whether IL-1beta plays a role in the pathogenesis of cigarette smoke-induced emphysema and small airway remodeling, IL-1 receptor knockout (IL1RKO), TNF-alpha receptor knockout (TNFRKO), or C57Bl/6 (control) mice were exposed to cigarette smoke acutely or for up to 6 months. With a single acute exposure, smoke elevated IL-1beta in C57Bl/6 mice. IL1RKO mice were protected against acute smoke-mediated increases in lavage inflammatory cells and matrix breakdown. In C57Bl/6 mice, acute smoke-mediated increases in inflammatory cells, serum IL-1beta, and serum TNF-alpha were blocked by z-VAD-fmk, a pan-caspase inhibitor, or z-WEHD-fmk, a caspase-1 (IL-1-converting enzyme, [ICE]) inhibitor. With 6 months of exposure, IL-1beta was no longer increased, but IL-18 was elevated. After 6 months of exposure, IL1RKO mice were 65% protected against emphysema, whereas TNFRKO mice were 83% protected. Both strains were completely protected against small airway remodeling. Lavage desmosine, hydroxyproline, and hyaluronan, matrix breakdown markers, were elevated in C57 but not IL1RKO mice. We conclude that IL-1beta plays a significant role in induction of murine emphysema and small airway remodeling, and is comparable to TNF-alpha in its effects. The protective effects of caspase inhibitors appear to be related to inhibition of ICE and raise the question of whether models that ameliorate emphysema with caspase inhibitors are really blocking IL-1beta (and IL-18) activation rather than blocking apoptosis.

Molecular mechanisms of corticosteroid resistance

Most patients with asthma are successfully treated with conventional therapy. Nevertheless, there is a small proportion of asthmatic patients, including present cigarette smokers and former cigarette smokers, who fail to respond well to therapy with high-dose glucocorticoids (GCs) or with supplementary therapy. In addition, high doses of steroids have a minimal effect on the inexorable decline in lung function in COPD patients and only a small effect on reducing exacerbations. GC insensitivity, therefore, presents a profound management problem in these patients. GCs act by binding to a cytosolic GC receptor (GR), which is subsequently activated and is able to translocate to the nucleus. Once in the nucleus, the GR either binds to DNA and switches on the expression of antiinflammatory genes or acts indirectly to repress the activity of a number of distinct signaling pathways such as nuclear factor (NF)-kappaB and activator protein (AP)-1. This latter step requires the recruitment of corepressor molecules. Importantly, this latter interaction is mutually repressive in that high levels of NF-kappaB and AP-1 attenuate GR function. A failure to respond may therefore result from reduced GC binding to GR, reduced GR expression, enhanced activation of inflammatory pathways, or lack of corepressor activity. These events can be modulated by oxidative stress, T-helper type 2 cytokines, or high levels of inflammatory mediators, all of which may lead to a reduced clinical outcome. Understanding the molecular mechanisms of GR action, and inaction, may lead to the development of new antiinflammatory drugs or may reverse the relative steroid insensitivity that is characteristic of patients with these diseases.

The many "small COPDs": COPD should be an orphan disease

COPD is one of the most common causes of morbidity and mortality. Perhaps paradoxically, COPD also should be an orphan disease. Importantly, this could advance the development of treatments for COPD. There are two criteria for orphan status in the United States. Most widely known is the criterion of < 200,000 affected individuals; however, secondarily, is the impossibility for development costs to be recovered during the patent life of a product. COPD should qualify for the first criterion if the various conditions that comprise COPD are regarded separately. The subphenotyping of COPD into separate groups based on mechanism sets the stage for the rational development of therapeutics. In addition, many candidate treatments may alter the natural history of COPD. Testing them, however, will require large studies for a duration that will compromise the commercial life of any resulting product. Orphan status, therefore, could facilitate the development of treatments for both phenotypic subsets of COPD patients as well as aid the development of agents to alter the natural history of the disease. Post-drug approval regulations could require that agents approved under the orphan provisions are prospectively monitored, assuring that rigorous longitudinal data are generated. This approach could encourage the pharmaceutical industry to stratify studies based on a more detailed characterization of study subjects at baseline, thus approaching "many small COPDs" instead of a single large and heterogeneous COPD. This strategy may help to address the increasing burden that COPD presents and for which no novel clinical class of treatment has been introduced for 30 years.

Anti-TNF-alpha therapies in chronic obstructive pulmonary diseases

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and asthma are chronic diseases in which inflammation of the airways leads to progressive transient airway obstruction and TNF-alpha plays an important pro-inflammatory role.

OBJECTIVE

To assess the plausibility of anti-TNF-alpha therapies playing an anti-inflammatory role in asthma and COPD.

METHODS

Scientific rationale of TNF-alpha targeting in asthma and COPD was assessed individually and the available data on the use of anti-TNF-alpha in each disease were reviewed.

RESULTS AND CONCLUSION

Anti-TNF-alpha therapies demonstrate different efficacies in asthma and COPD and further supportive preclinical and clinical data are needed, especially about subsets of certain diseases which could benefit the most from these therapies.

The TNFalpha gene relates to clinical phenotype in alpha-1-antitrypsin deficiency

BACKGROUND

Genetic variation may underlie phenotypic variation in chronic obstructive pulmonary disease (COPD) in subjects with and without alpha 1 antitrypsin deficiency (AATD). Genotype specific sub-phenotypes are likely and may underlie the poor replication of previous genetic studies. This study investigated subjects with AATD to determine the relationship between specific phenotypes and TNFalpha polymorphisms.

METHODS

424 unrelated subjects of the PiZZ genotype were assessed for history of chronic bronchitis, impairment of lung function and radiological presence of emphysema and bronchiectasis. A subset of subjects with 3 years consecutive lung function data was assessed for decline of lung function. Four single nucleotide polymorphisms (SNPs) tagging TNFalpha were genotyped using TaqMan(R) genotyping technologies and compared between subjects affected by each phenotype and those unaffected. Plasma TNFalpha levels were measured in all PiZZ subjects.

RESULTS

All SNPs were in Hardy-Weinberg equilibrium. A significant difference in rs361525 genotype (p = 0.01) and allele (p = 0.01) frequency was seen between subjects with and without chronic bronchitis, independent of the presence of other phenotypes. TNFalpha plasma level showed no phenotypic or genotypic associations.

CONCLUSION

Variation in TNFalpha is associated with chronic bronchitis in AATD.

Malignancy and biologic therapy in rheumatoid arthritis

PURPOSE OF REVIEW

Owing to the complex functions of the inflammatory response systems--potentially or clearly of importance in human carcinogenesis--that biological therapies interfere with uncertainty regarding their safety profile for malignancy is more or less expected. This uncertainty has been further sparked by the apparent discordance between trial data and observational studies of anti-TNF agents, and the methodological challenges inherent in addressing the safety profile of new drugs for delayed and multifactorial events like cancer.

RECENT FINDINGS

This review provides a summary of the pattern of cancer seen in patients with rheumatoid arthritis not treated with biologics, and the currently published data on cancer risk following treatment with biologics in patients with rheumatoid arthritis, primarily anti-TNF therapy.

SUMMARY

Published data currently do not exclude clinically important increased risks, nor do they refute beneficial effects. As per definition, much of the currently available safety data from trials or clinical practice do not capture the impact of either any effect that biological therapy might have on early events in carcinogenesis, or of sustained exposure to biologics. Beyond the risk of de-novo cancer development, several other clinically important aspects of cancer safety remain to be addressed, including issues of prognosis, progression, and relapse.

Therapeutic options in acute severe ulcerative colitis

Ulcerative colitis is a relapsing-remitting inflammatory disease affecting the colon and is associated with considerable morbidity. In acute severe attacks, there continues to be an associated mortality rate of 1-2%, even in specialist units. During an acute severe exacerbation, approximately two-thirds of patients will respond to intravenous corticosteroid therapy, the accepted first-line therapy in such cases. For steroid-refractory patients, options are limited to surgery (colectomy) or second-line agents, such as ciclosporin or infliximab, used in an attempt to salvage the colon. Considerable debate exists over the optimal management of such patients. During the last decade, an increased understanding of the pathogenesis of inflammatory bowel disease has led to the rapid development of other biological agents, such as basiliximab and visilizumab. Novel methods, such as leucopheresis, have been studied and other established immunomodulatory agents, such as tacrolimus, have also been suggested. The purpose of this review is to highlight some of the areas of recent development in the treatment of acute severe ulcerative colitis and review important safety data, with a particular emphasis on biological agents.

Dynamics of pro-inflammatory and anti-inflammatory cytokine release during acute inflammation in chronic obstructive pulmonary disease: an ex vivo study

Background

Exacerbations of Chronic obstructive pulmonary disease (COPD) are an important cause of the morbidity and mortality associated with the disease. Strategies to reduce exacerbation frequency are thus urgently required and depend on an understanding of the inflammatory milieu associated with exacerbation episodes. Bacterial colonisation has been shown to be related to the degree of airflow obstruction and increased exacerbation frequency. The aim of this study was to asses the kinetics of cytokine release from COPD parenchymal explants using an ex vivo model of lipopolysaccharide (LPS) induced acute inflammation.

Methods

Lung tissue from 24 patients classified by the GOLD guidelines (7F/17M, age 67.9 ± 2.0 yrs, FEV₁ 76.3 ± 3.5% of predicted) and 13 subjects with normal lung function (8F,5M, age 55.6 ± 4.1 yrs, FEV₁ 98.8 ± 4.1% of predicted) was stimulated with 100 ng/ml LPS alone or in combination with either neutralising TNFα or IL-10 antibodies and supernatant collected at 1,2,4,6,24, and 48 hr time points and analysed for IL-1β, IL-5, IL-6, CXCL8, IL-10 and TNFα using ELISA. Following culture, explants were embedded in glycol methacrylate and immunohistochemical staining was conducted to determine the cellular source of TNFα, and numbers of macrophages, neutrophils and mast cells.

Results

In our study TNFα was the initial and predictive cytokine released followed by IL-6, CXCL8 and IL-10 in the cytokine cascade following LPS exposure. The cytokine cascade was inhibited by the neutralisation of the TNFα released in response to LPS and augmented by the neutralisation of the anti-inflammatory cytokine IL-10. Immunohistochemical analysis indicated that TNFα was predominantly expressed in macrophages and mast cells. When patients were stratified by GOLD status, GOLD I (n = 11) and II (n = 13) individuals had an exaggerated TNFα responses but lacked a robust IL-10 response compared to patients with normal lung function (n = 13).

Conclusion

We report on a reliable ex vitro model for the investigation of acute lung inflammation and its resolution using lung parenchymal explants from COPD patients. We propose that differences in the production of both TNFα and IL-10 in COPD lung tissue following exposure to bacterial LPS may have important biological implications for both episodes of exacerbation, disease progression and amelioration.

Mechanisms of cigarette smoke-induced COPD: insights from animal models

Cigarette smoke-induced animal models of chronic obstructive pulmonary disease support the protease-antiprotease hypothesis of emphysema, although which cells and proteases are the crucial actors remains controversial. Inhibition of either serine or metalloproteases produces significant protection against emphysema, but inhibition is invariably accompanied by decreases in the inflammatory response to cigarette smoke, suggesting that these inhibitors do more than just prevent matrix degradation. Direct anti-inflammatory interventions are also effective against the development of emphysema, as are antioxidant strategies; the latter again decrease smoke-induced inflammation. There is increasing evidence for autoimmunity, perhaps directed against matrix components, as a driving force in emphysema. There is intriguing but controversial animal model evidence that failure to repair/failure of lung maintenance also plays a role in the pathogenesis of emphysema. Cigarette smoke produces small airway remodeling in laboratory animals, possibly by direct induction of fibrogenic growth factors in the airway wall, and also produces pulmonary hypertension, at least in part through direct upregulation of vasoactive mediators in the intrapulmonary arteries. Smoke exposure causes goblet cell metaplasia and excess mucus production in the small airways and proximal trachea, but these changes are not good models of either chronic bronchitis or acute exacerbations. Emphysema, small airway remodeling, pulmonary hypertension, and mucus production appear to be at least partially independent processes that may require different therapeutic approaches.

Targeting lung inflammation: novel therapies for the treatment of COPD

Chronic obstructive pulmonary disease (COPD) is a global health problem. As understanding of pathology of COPD has increased it has been established that COPD is associated with the progressive pulmonary inflammation and destruction of lung parenchyma (emphysema) that relate to disease severity. Therefore, it is anticipated that drugs that reduce pulmonary inflammation will provide effective, disease modifying therapy for COPD. Several specific therapies are directed against the influx of inflammatory cells into the airways and lung parenchyma that occurs in COPD; these include agents directed against cytokines and chemokines. Broad-range anti-inflammatory drugs are now in phase III development for COPD; they include inhibitors of phosphodiesterase 4 (PDE4). Other drugs that inhibit cell signaling include inhibitors of p38 mitogen-activated protein kinase (MAPK), nuclear factor-κB (NF-κB), and phosphoinositide-3-kinase (PI3K). There is also a search for inhibitors of proteinases and matrix metalloproteinases (MMPs) to prevent lung destruction and the development of emphysema. This review highlights studies on novel or potential anti-inflammatory agents that might be considered in the development of new future therapies for COPD.

Cardiovascular risk in chronic obstructive pulmonary disease

Cardiovascular disease (CVD) contributes significantly to morbidity and mortality in COPD. There is a high prevalence of traditional risk factors in this patient group including smoking, sedentary behaviour and low socio-economic class. However, large studies have shown that airflow limitation is an independent risk factor for CVD. Therefore there may be a 'COPD effect' that contributes to CVD in this condition, adding to the body of evidence that COPD has important systemic consequences, as well as being a lung disease. In this article, we review the evidence for CVD in COPD. Next, we examine systemic factors present in COPD, and link these to the pathogenesis of atherosclerosis, including inflammation, oxidative stress and hypoxia. Finally, we review those studies that have investigated therapeutic interventions in COPD that may modify cardiovascular risk.

Haemophilus influenzae lysate induces aspects of the chronic obstructive pulmonary disease phenotype

Nontypeable Haemophilus influenzae (NTHi) commonly colonizes the lower airways of patients with chronic obstructive pulmonary disease (COPD). Whether it contributes to COPD progression is unknown. Here, we determined which aspects of the COPD phenotype can be induced by repetitive exposure to NTHi products. Mice were exposed weekly to an aerosolized NTHi lysate, and inflammation was evaluated by measurement of cells and cytokines in bronchoalveolar lavage fluid (BALF) and immunohistochemical staining; structural changes were evaluated histochemically by periodic acid fluorescent Schiff's reagent, Masson's trichrome, and Picrosirius red staining; mucin gene expression was measured by quantitative RT-PCR; and the role of TNF-alpha was examined by transgenic airway overexpression and use of an inhibitory antibody. NTHi lysate induced rapid activation of NF-kappaB in airway cells and increases of inflammatory cytokines and neutrophils in BALF. Repetitive exposure induced infiltration of macrophages, CD8+ T cells, and B cells around airways and blood vessels, and collagen deposition in airway and alveolar walls, but airway mucin staining and gel-forming mucin transcripts were not increased. Transgenic overexpression of TNF-alpha caused BALF neutrophilia and inflammatory cell infiltration around airways, but not fibrosis, and TNF-alpha neutralization did not reduce BALF neutrophilia in response to NTHi lysate. In conclusion, NTHi products elicit airway inflammation in mice with a cellular and cytokine profile similar to that in COPD, and cause airway wall fibrosis but not mucous metaplasia. TNF-alpha is neither required for inflammatory cell recruitment nor sufficient for airway fibrosis. Colonization by NTHi may contribute to the pathogenesis of small airways disease in patients with COPD.

Update on the pharmacologic therapy for chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease is a treatable disease characterized by progressive airflow limitation. Prevention of disease progression; improvement of symptoms, exercise tolerance, and health status; and decrease in exacerbations and mortality are the goals of management. Inhaled short-acting bronchodilators are recommended for symptoms in mild disease, whereas inhaled long-acting bronchodilators are recommended for maintenance therapy of daily symptoms. When symptoms are not controlled using one bronchodilator, combining bronchodilators may be more effective. Combining a long-acting beta-agonist with an inhaled corticosteroid is more effective than either agent alone. Several novel therapies are in different stages of development.

Clinical pharmacokinetics and use of infliximab

Tumor necrosis factor-alpha (TNFalpha) is a key proinflammatory cytokine involved in chronic inflammatory diseases. Infliximab, a chimeric (human-murine) monoclonal IgG1 anti-TNFalpha antibody, is used in the treatment of Crohn's disease (including fistulising disease) and rheumatoid arthritis (in combination with methotrexate) if standard treatments have failed. The indications for infliximab have recently been expanded to include ankylosing spondylitis, psoriatic arthritis, psoriasis and ulcerative colitis. The biological agent infliximab is given by multiple intravenous infusions in a dosage of 3-5 mg/kg (initially at weeks 0, 2 and 6; subsequently in intervals of 4-8 weeks). In controlled trials, clinical response rates of 20-40% have been achieved with such regimens in Crohn's disease and rheumatoid arthritis. However, the therapeutic benefits must be balanced against the risks of a variety of severe adverse events (e.g. severe infections including tuberculosis, hepatotoxicity, infusion reactions, serum sickness-like disease and lymphoma). Following single and multiple infusions of infliximab, no relevant differences in median concentration-time profiles have been observed between patients with Crohn's disease, patients with rheumatoid arthritis and patients with psoriasis. The apparent volume of distribution of the high-molecular-weight infliximab (149.1 kDa) is low (3-6L) and represents the intravascular space. The long persistence in this compartment (elimination half-life 7-12 days, mean residence time 12-17 days) is due to the very low systemic clearance of about 11-15 mL/hour (0.18-0.25 mL/minute). Elimination of infliximab is most probably accomplished through degradation by unspecific proteases. During multiple infusions (every 4-8 weeks), no accumulation was observed, and serum concentrations and the area under the plasma concentration-time curve of infliximab increased in proportion to the infused dose, indicating linear pharmacokinetics. Co-medication with methotrexate delayed the decline in the serum concentrations of infliximab. When relating serum concentrations to the clinical response in patients with rheumatoid arthritis and patients with Crohn's disease, it can be assumed that trough concentrations above 1 microg/mL could be used as a kind of therapeutic target. In the future, identification of biomarkers for (non-)response and risk factors for adverse drug reactions would be very helpful. Furthermore, combined biological, pharmacokinetic, pharmacogenomic and clinical studies have not yet been performed and are needed to optimise the therapeutic potential of infliximab, which is currently established as a rescue treatment in refractory patients.

Targeting TNF-alpha: a novel therapeutic approach for asthma

Approximately 5% to 10% of patients with asthma have severe disease that is refractory or poorly responsive to inhaled corticosteroid therapy. These patients represent an important unmet clinical need because they experience considerable morbidity and mortality and consume a disproportionately large amount of health care resources. TNF-alpha is a proinflammatory cytokine that has been implicated in many aspects of the airway pathology in asthma. Evidence is emerging to suggest that it might play an important role in severe refractory disease. The development of novel TNF-alpha antagonists has allowed us to test the role of this cytokine in vivo. Preliminary studies have demonstrated an improvement in asthma quality of life, lung function, and airway hyperresponsiveness and a reduction in exacerbation frequency in patients treated with anti-TNF-alpha therapy. However, there is marked heterogeneity in response, suggesting that benefit is likely to be reserved to a small subgroup. Importantly, where efficacy is reported, this also needs to be considered in the context of concerns about the safety of anti-TNF-alpha therapies. Therefore the challenge for clinicians is to evaluate the risk/benefit ratio of these therapies in individual patients with asthma.

Targeting systemic inflammation: novel therapies for the treatment of chronic obstructive pulmonary disease

The increasing evidence that inflammation in the lungs leads to the structural changes observed in chronic obstructive pulmonary disease, whereas extrapulmonary symptoms and comorbidities may be systemic manifestations of these inflammatory processes, highlights an urgent need to discover novel, effective anti-inflammatory treatments for this disease. Some studies are suggesting that, by decreasing dynamic hyperinflation, bronchodilators might reduce systemic inflammation; inhaled corticosteroids and their combination with long-acting beta2-agonists might contribute to this goal. Even so, the opinion that suppression of the inflammatory response might improve systemic complications is stimulating a search for novel anti-inflammatory therapies. Many drugs include those that inhibit the recruitment and activation of inflammatory cells and/or antagonise their products. However, many of these therapeutic strategies are not specific for neutrophilic inflammation because they affect other cell types, thus, it is difficult to interpret whether any clinical benefit observed is a result of a reduction in airway neutrophils. In any case, there is some evidence that drugs used to treat a co-morbid condition, such as statins, angiotensin converting enzyme (ACE) inhibitors and angiontensin II type 1 (AT1) receptor blockers as well as glycosaminoglycans and peroxisome proliferator-activated receptor (PPAR) agonists, might benefit chronic obstructive pulmonary disease patients because they deal with the extrapulmonary, systemic component of chronic obstructive pulmonary disease.

Treating systemic effects of COPD

The emerging recognition that chronic obstructive pulmonary disease (COPD) is a complex disorder, characterized not only by local pulmonary inflammation, but also by systemic inflammation that might have an adverse impact on various extrapulmonary organs, such as the blood vessels and the heart, among others, emphasizes the need for new and more effective forms of therapy for this debilitating disorder. Fortunately, many of the 'standard' therapeutic options used to treat COPD have the potential to influence systemic inflammation. Moreover, several new therapeutic strategies aimed at controlling the underlying inflammatory processes of COPD more specifically are under development. Unfortunately, we still do not know whether treatment of lung inflammation decreases, for example, the risk of acute cardiac events, progression of atherosclerosis or thrombotic events. It is also unclear whether, alternatively, treatment of heart disease can affect the progression of lung disease. Nonetheless, initial data seem to indicate that drugs, such as statins, ACE inhibitors, AT1 receptor blockers and PPAR agonists, used to treat a co-morbid condition have the potential to benefit COPD patients.

What have we learned from large drug treatment trials in COPD?

Although the development of effective treatments for patients with chronic obstructive pulmonary disease (COPD) has not been seen as a high priority, the past decade has seen a substantial increase in the number of clinical studies examining different treatments for this disease. Large studies are needed to adequately assess the effectiveness of treatment because of the chronic nature of the disease and the intermittent occurrence of some key outcomes such as exacerbations. Data from randomised controlled trials show that treatment improves exercise performance by increasing lung volume rather than changing expiratory flow. Although assessment of lung function remains the cornerstone of drug assessment, improvements in health status, the number of exacerbations and admissions to hospital are now recognised as important treatment outcomes. Randomised controlled trial data provide the best evidence for treatment efficacy, but results of these studies can be affected by differences in inclusion criteria and patient dropout during the study. Bronchodilator reversibility testing does not reliably define subgroups that will respond to a particular treatment. Carefully done and adequately powered clinical trials continue to inform, not only our views about treatment, but also our understanding of COPD and how it is best assessed and managed. Ensuring that these expensive studies are done objectively to the highest standard is an important goal for the next decade.

Aspects on pathophysiological mechanisms in COPD

Chronic obstructive pulmonary disease (COPD) is a condition which is characterized by irreversible airway obstruction due to narrowing of small airways, bronchiolitis, and destruction of the lung parenchyma, emphysema. It is the fourth most common cause of mortality in the world and is expected to be the third most common cause of death by 2020. The main cause of COPD is smoking but other exposures may be of importance. Exposure leads to airway inflammation in which a variety of cells are involved. Besides neutrophil granulocytes, macrophages and lymphocytes, airway epithelial cells are also of particular importance in the inflammatory process and in the development of emphysema. Cell trafficking orchestrated by chemokines and other chamoattractants, the proteinase-antiproteinase system, oxidative stress and airway remodelling are central processes associated with the development of COPD. Recently systemic effects of COPD have attracted attention and the importance of systemic inflammation has been recognized. This seems to have direct therapeutic implications as treatment with inhaled glucocorticosteroids has been shown to influence mortality. The increasing body of knowledge regarding the inflammatory mechanism in COPD will most likely have implications for future therapy and new drugs, specifically aimed at interaction with the inflammatory processes, are currently being developed.

COPD exacerbations: defining their cause and prevention

Exacerbations of chronic obstructive pulmonary disease (COPD) are episodes of worsening of symptoms, leading to substantial morbidity and mortality. COPD exacerbations are associated with increased airway and systemic inflammation and physiological changes, especially the development of hyperinflation. They are triggered mainly by respiratory viruses and bacteria, which infect the lower airway and increase airway inflammation. Some patients are particularly susceptible to exacerbations, and show worse health status and faster disease progression than those who have infrequent exacerbations. Several pharmacological interventions are effective for the reduction of exacerbation frequency and severity in COPD such as inhaled steroids, long-acting bronchodilators, and their combinations. Non-pharmacological therapies such as pulmonary rehabilitation, self-management, and home ventilatory support are becoming increasingly important, but still need to be studied in controlled trials. The future of exacerbation prevention is in assessment of optimum combinations of pharmacological and non-pharmacological therapies that will result in improvement of health status, and reduction of hospital admission and mortality associated with COPD.

Lysophosphatidic acid decreases epidermal growth factor receptor binding in airway epithelial cells

We showed previously that treatment of human airway smooth muscle cells and lung fibroblasts with lysophosphatidic acid (LPA) increases the binding of epidermal growth factor (EGF) to EGF receptors (EGFRs). The purpose of this study was to determine whether LPA also regulates EGFR binding in airway epithelial cells. Airway epithelial cells were incubated in the absence or presence of 10 microM LPA for increasing times, and binding of 125I-EGF to intact cells on ice was measured. Exposure to LPA for only 15 min caused a 30 to 70% decrease in EGFR binding in a dose-dependent manner, depending on the cell line. This decrease in binding was sustained to at least 18 h in BEAS-2B and primary human bronchial epithelial cells. In contrast, the LPA-induced decrease in binding reversed rapidly in two lung cancer epithelial cell lines, H292 and A549, returning to control levels within 3 h. LPA increased phosphorylation of the EGFR in BEAS-2B cells, and this phosphorylation was inhibited by both 4-(3'-chloroanilino)-6,7-dimethoxy-quinazoline (AG1478; EGFR tyrosine kinase inhibitor) and N-[(2R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl]-l-tryptophan methylamide (GM6001; matrix metalloproteinase inhibitor) but not by CRM197 (heparin-binding EGF inhibitor). AG-1478 and GM6001 also inhibited the LPA-induced decrease in EGFR binding but only by 50%, suggesting only partial involvement of EGFR transactivation in the decrease in EGFR binding. In summary, LPA stimulates a decrease in EGFR binding in airway epithelial cells that is sustained in normal cells but that rapidly reverses in cancer cells. LPA-induced transactivation of EGFRs occurs and contributes to the decrease in EGFR binding, but additional pathway(s) may also be involved.

TNF-alpha antagonists and the prevention of hospitalisation for chronic obstructive pulmonary disease

BACKGROUND

TNF-alpha may be important in the pathogenesis of COPD. Consequently, the use of TNF-alpha antagonists has been advocated for its treatment.

METHODS

We conducted an observational study to evaluate the effectiveness of TNF-alpha antagonists in preventing COPD hospitalisations in a cohort of patients diagnosed with both RA and COPD identified from a health claims database. A nested case-control approach was used to match each case hospitalised to 10 controls on age and cohort entry date. Data on prescribed medications during the year prior to the index date were obtained. Rate ratios (RR) of COPD hospitalisation were estimated by conditional logistic regression, after adjustment for COPD severity and concomitant RA medication use.

RESULTS

The cohort included 15,771 subjects with both RA and COPD, of which 1205 were hospitalised for COPD during follow-up. The adjusted RR of COPD hospitalisation associated with the use of TNF-alpha antagonists was 0.62 (95% confidence interval (CI) 0.43-0.89). This rate reduction was due to etanercept (RR 0.49, 95% CI 0.29-0.82) but not infliximab (RR 0.95, 95% CI 0.59-1.52).

CONCLUSION

Our finding of a halving in the rate of COPD hospitalisation associated with the use of etanercept corroborates the potential importance of TNF-alpha in the pathogenesis of COPD. This study supports the initiation of randomised controlled trials of this TNF-alpha antagonist among COPD patients at high risk of severe exacerbations.