Regional differences in airway susceptibility to cigarette smoke: An investigational case study of epithelial function and gene alterations inin vitroairway epithelial three-dimensional cultures

Cigarette smoke (CS) is a risk factor contributing to lung remodeling in chronic obstructive pulmonary disease (COPD). COPD is a heterogeneous disease because many factors contribute in varying degrees to the resulting airflow limitations in different regions of the respiratory tract. This heterogeneity makes it difficult to understand mechanisms behind COPD development. In the current study, we investigate the regional heterogeneity of the acute response to CS exposure between large and small airways using in vitro three-dimensional (3D) cultures. We used two in vitro 3D human airway epithelial tissues from large and small airway epithelial cells, namely, MucilAir™ and SmallAir™, respectively, which were derived from the same single healthy donor to eliminate donor differences. Impaired epithelial functions and altered gene expression were observed in SmallAir™ exposed to CS at the lower dose and earlier period following the last exposure compared with MucilAir™. In addition, severe damage in SmallAir™ was retained for a longer duration than MucilAir™. Transcriptomic analysis showed that although well-known CS-inducible biological processes (i.e. inflammation, cell fate, and metabolism) were disturbed with consistent activity in both tissues exposed to CS, we elucidated distinctively regulated genes in only MucilAir™ and SmallAir™, which were mostly related to catalytic and transporter activities. Our findings suggest that CS exposure elicited epithelial dysfunction through almost the same perturbed pathways in both airways; however, they expressed different genes related to metabolic and transporter activities in response to CS exposure which may contribute to cytotoxic heterogeneity to the response to CS in the respiratory tract.

Targeting defective pulmonary innate immunity - A new therapeutic option?

Chronic pulmonary conditions now account for 1 in 15 deaths in the US and mortality is increasing. Chronic obstructive pulmonary disease (COPD) is due to become the 3rd largest cause of mortality by 2030 and mortality from other respiratory conditions such as asthma, idiopathic pulmonary fibrosis and cystic fibrosis are not reducing. There is an urgent need for novel therapies to address this problem as many of the current strategies targeting inflammation are not sufficient. The innate immune system of the lung is an important defence against invading pathogens, but in many chronic pulmonary diseases, this system mounts an inappropriate response. In COPD, macrophages are increased in number, but fail to clear pathogens correctly and become highly activated. This leads to increased damage and remodelling of the airways. In idiopathic fibrosis, there is a switch of macrophage phenotype to a cell that promotes abnormal repair. Neutrophils also display dysfunction in COPD where aberrant migratory profiles may lead to increased damage to lung tissue and emphysema; while in cystic fibrosis the proteolytic lung environment damages neutrophil receptors leading to ineffective phagocytosis and migration. Targeting the innate immune system to restore 'normal function' could have enormous benefits. Improving phagocytosis of pathogens could reduce exacerbations and hence the associated decline in lung function, and novel therapeutics such as sulforaphane appear to do this in vitro. Other natural products such as resveratrol and derivatives also have anti-inflammatory properties. Statins have traditionally been used to manage cholesterol levels in hypercholesterolaemia, however these molecules also have beneficial effects on the innate immune cells. Statins have been shown to be anti-inflammatory and restore aberrant neutrophil chemotaxis in aged cells. Other possible agents that may be efficacious are senolytics. These compounds include natural products such as quercetin which have anti-inflammatory properties but can also suppress viral replication. As viruses have been shown to suppress phagocytosis of macrophages, it is possible that these compounds could have benefit during viral exacerbations to protect this innate response. These compounds demonstrate that it is possible to address defective innate responses in the lung but a better understanding of the mechanisms driving defective innate immunity in pulmonary disease may lead to improved therapeutics.

Butylphthalide ameliorates airway inflammation and mucus hypersecretion via NF-κB in a murine asthma model

Butylphthalide (NBP) is a phthalide compound contained in Angelicae Sinensis Radix which is one of the most widely used traditional Chinese medicines. This study aims to explore the therapeutic effect of NBP on airway inflammation, mucus hypersecretion and their possible mechanism in asthma mice. BALB/c mice were sensitized and challenged with ovalbumin (OVA) for establishment of asthma model and then treated with NBP during day 22-77. The pulmonary function of the mice was determined, and the pathology of lung tissue and goblet cell hyperplasia were observed through analyzing inflammation scores and goblet cell percentage, respectively. Cytokine IL-4, IL-8, IL-13 and tumor necrosis factor-alpha (TNF-α) in bronchoalveolar lavage fluid (BALF) and total immunogloblin E (T-IgE) and OVA-specific IgE in serum were examined by enzyme-linked immunosorbent assay (ELISA). The expressions of Mucin 5AC (Muc5ac) and nuclear transcription factor-kappa B (NF-κB) in lung tissues were evaluated by immunohistochemistry, western blot and real-time polymerase chain reaction (RT-PCR). The results show that 50 mg/kg NBP significantly reduced OVA-induced increase in inflammation scoring, goblet cell percentage and mucus secretion of airway tissue, and improved the pulmonary function. NBP could also decrease IL-4, IL-8 IL-13, and TNF-α in BALF and T-IgE and OVA-specific IgE in serum. The expression of Muc5ac and NF-κB in lung tissue was significantly down-regulated after NBP treatment. This study suggested that NBP may effectively inhibit airway inflammation and mucus hypersecretion in asthma by modulating NF-κB activation.

Differential coexpression networks in bronchiolitis and emphysema phenotypes reveal heterogeneous mechanisms of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease with multiple molecular mechanisms. To investigate and contrast the molecular processes differing between bronchiolitis and emphysema phenotypes of COPD, we downloaded the GSE69818 microarray data set from the Gene Expression Omnibus (GEO), which based on lung tissues from 38 patients with emphysema and 32 patients with bronchiolitis. Then, weighted gene coexpression network analysis (WGCNA) and differential coexpression (DiffCoEx) analysis were performed, followed by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes enrichment analysis (KEGG) analysis. Modules and hub genes for bronchiolitis and emphysema were identified, and we found that genes in modules linked to neutrophil degranulation, Rho protein signal transduction and B cell receptor signalling were coexpressed in emphysema. DiffCoEx analysis showed that four hub genes (IFT88, CCDC103, MMP10 and Bik) were consistently expressed in emphysema patients; these hub genes were enriched, respectively, for functions of cilium assembly and movement, proteolysis and apoptotic mitochondrial changes. In our re‐analysis of GSE69818, gene expression networks in relation to emphysema deepen insights into the molecular mechanism of COPD and also identify some promising therapeutic targets.

Persistent induction of goblet cell differentiation in the airways: Therapeutic approaches

Dysregulated induction of goblet cell differentiation results in excessive production and retention of mucus and is a common feature of several chronic airways diseases. To date, therapeutic strategies to reduce mucus accumulation have focused primarily on altering the properties of the mucus itself, or have aimed to limit the production of mucus-stimulating cytokines. Here we review the current knowledge of key molecular pathways that are dysregulated during persistent goblet cell differentiation and highlights both pre-existing and novel therapeutic strategies to combat this pathology.

TRPC Channels in Health and Disease

This chapter offers a brief introduction of the functions of TRPC channels in non-neuronal systems. We focus on three major organs of which the research on TRPC channels have been most focused on: kidney, heart, and lung. The chapter highlights on cellular functions and signaling pathways mediated by TRPC channels. It also summarizes several inherited diseases in humans that are related to or caused by TRPC channel mutations and malfunction. A better understanding of TRPC channels functions and the importance of TRPC channels in health and disease should lead to new insights and discovery of new therapeutic approaches for intractable disease.

Macrophage Dysfunction in Respiratory Disease

In the healthy lung, macrophages maintain homeostasis by clearing inhaled particles, bacteria, and removing apoptotic cells from the local pulmonary environment. However, in respiratory diseases including chronic obstructive pulmonary disease (COPD), asthma, and cystic fibrosis, macrophages appear to be dysfunctional and may contribute to disease pathogenesis. In COPD, phagocytosis of bacterial species and apoptotic cells by both alveolar macrophages and monocyte-derived macrophages is significantly reduced, leading to colonization of the lung with pathogenic bacteria. COPD macrophages also release high levels of pro-inflammatory cytokines and chemokines, including CXCL8, TGFβ, and CCL2, driving recruitment of other inflammatory cells including neutrophils and monocytes to the lungs and promoting disease progression.In asthma, defective phagocytosis and efferocytosis have also been reported, and macrophages appear to have altered cell surface receptor expression; however, it is as yet unclear how this contributes to disease progression but may be important in driving Th2-mediated inflammation. In cystic fibrosis, macrophages also display defective phagocytosis, and reduced bacterial killing, which may be driven by the pro-inflammatory environment present in the lungs of these patients.The mechanisms behind defective macrophage function in lung diseases are not currently understood, but potential mechanisms include alterations in phagocytic receptor expression levels, oxidative stress, but also the possibility that specific diseases are associated with a specific, altered, macrophage phenotype that displays reduced function. Identification of the mechanisms responsible may present novel therapeutic opportunities for treatment.

Repeated Activation of Lung Invariant NKT Cells Results in Chronic Obstructive Pulmonary Disease-Like Symptoms

Chronic obstructive pulmonary disease (COPD) is characterized by chronic airway inflammation, mucus hypersecretion, and emphysema, which lead to reduced lung function and breathlessness. The pathologies of COPD are due to an abnormal immune response. Invariant natural killer T (iNKT) cells are an important population of innate lymphocytes and have been implicated in the regulation of immune responses associated with a broad range of diseases including COPD. We have here analyzed the role of iNKT cells in a model of COPD induced by repeated intranasal administration of iNKT cell agonist α-galactosylceramide (α-GalCer). Our results demonstrated that mice that received repeated intranasal administration of α-GalCer had molecular and inflammatory features of COPD including airway inflammation with significant increases in infiltration of macrophages and lymphocytes, CD8⁺ T cells, as well as proinflammatory cytokines IL-6 and TNF-α. In particular, these mice also showed the presence of pulmonary emphysema, mucus production, and pulmonary fibrosis. Furthermore, neutralization of IL-4 reduced α-GalCer induced emphysema. This study indicates the importance of iNKT cells in the pathogenesis of COPD by an IL-4 dependent mechanism.

Bone marrow-derived multipotent stromal cells attenuate inflammation in obliterative airway disease in mouse tracheal allografts

Obliterative bronchiolitis (OB) remains the most significant cause of death in long-term survival of lung transplantation. Using an established murine heterotopic tracheal allograft model, the effects of different routes of administration of bone marrow-derived multipotent stromal cells (MSCs) on the development of OB were evaluated. Tracheas from BALB/c mice were implanted into the subcutaneous tissue of major histocompatibility complex- (MHC-) disparate C57BL/6 mice. At the time of transplant, bone marrow-derived MSCs were administered either systemically or locally or via a combination of the two routes. The allografts were explanted at various time points after transplantation and were evaluated for epithelial integrity, inflammatory cell infiltration, fibrosis, and luminal obliteration. We found that the most effective route of bone marrow-derived MSC administration is the combination of systemic and local delivery. Treatment of recipient mice with MSCs suppressed neutrophil, macrophage, and T-cell infiltration and reduced fibrosis. These beneficial effects were observed despite lack of significant MSC epithelial engraftment or new epithelial cell generation. Our study suggests that optimal combination of systemic and local delivery of MSCs may ameliorate the development of obliterative airway disease through modulation of immune response.

Molecular mechanisms of reactive oxygen species-related pulmonary inflammation and asthma

Asthma is a highly relevant disorder that can be induced by many environmental factors such as allergens and pollutants. One of the most critical pathological symptoms of asthma is airway inflammation. In order to identify a cause of respiratory inflammation, we thoroughly examine the unique role of reactive oxygen species (ROS). Evidence supports that the inhalation of aggravating compounds such as allergens can promote the increased generation of ROS. Accordingly, ROS have a proven role in the cellular signaling cascades of many respiratory diseases that cause respiratory inflammation, including asthma. Although there is no known cure for asthma, current treatments effectively lessen the inflammation symptom. Based on the investigations of asthma pathogenesis and the mechanism of ROS formation, we have identified several novel anti-inflammatory therapeutic treatments, shedding light on a fundamental understanding for the cure of this disorder. In this review, we will outline the pathogenesis of asthma and its relationship to ROS, oxidative stress, and pulmonary inflammation.

Vitamin D modulates airway smooth muscle function in COPD

COPD is a disease manifested as persistent airflow obstruction with an enhanced inflammatory response in the airways and lungs to noxious particles and gases which evokes symptoms of dyspnea on exertion, cough and mucus production. Airway smooth muscle plays a central role in the COPD diathesis and is implicated in many aspects of COPD pathogenesis. Vitamin D deficiency has been associated with COPD severity and studies suggest a role for Vitamin D as a treatment for COPD. In this review, we describe the effects of 1,25-dihydroxyvitamin D on airway smooth muscle function, including agonist-induced shortening, secretion of inflammatory mediators, and myocyte hypertrophy and hyperplasia.

Cadherin-11 contributes to pulmonary fibrosis: potential role in TGF-β production and epithelial to mesenchymal transition

Pulmonary fibrosis, characterized by excess deposition of extracellular matrix by myofibroblasts, is a serious component of chronic lung diseases. Cadherin-11 (CDH11) is increased in wound healing and fibrotic skin. We hypothesized that CDH11 is increased in pulmonary fibrosis and contributes its development. CDH11 expression was assessed in lung tissue from idiopathic pulmonary fibrosis patients. The role of CDH11 in lung fibrosis was determined using the bleomycin model of pulmonary fibrosis, and in vitro analyses were performed on A549 cells during the process of epithelial to mesenchymal transition (EMT). Immunohistochemical studies demonstrated CDH11 expression on fibroblasts, epithelial cells, and alveolar macrophages of patients with pulmonary fibrosis and mice given bleomycin. Interestingly, CDH11-deficient mice had decreased fibrotic endpoints in the bleomycin model of pulmonary fibrosis compared to wild-type mice. Furthermore, anti-CDH11-neutralizing monoclonal antibodies successfully treated established pulmonary fibrosis induced by bleomycin. TGF-β levels were reduced in bronchoalveolar lavage (BAL) fluid, BAL cells, and primary alveolar macrophages from CDH11-deficient mice. Mechanistic studies demonstrated that TGF-β up-regulated CDH11 expression on A549 cells, and inhibition of CDH11 expression using siRNA reduced TGF-β-induced EMT. Together, these results identify CDH11 as a novel therapeutic target for pulmonary fibrosis.

Development of inhalable nanocrystalline solid dispersion of tranilast for airway inflammatory diseases

Tranilast (TL), an antiallergic agent, has been clinically used in the treatment of bronchial asthma, although the clinical use of TL is limited because of its poor solubility and systemic side effects. To overcome these drawbacks, a novel respirable powder (RP) of TL for inhalation therapy was developed using nanocrystal solid dispersion of TL (CSD/TL). In the CSD/TL, wet-milled crystalline TL particles with a mean diameter of 122 nm were dispersed, and there was a marked improvement in dissolution behavior of the CSD/TL-RP compared with that of a physical mixture of TL and carrier. Laser diffraction and cascade impactor analyses on the CSD/TL-RP demonstrated high dispersibility and deposition in the respiratory organs with emitted dose and fine particle fraction of ca. 98 and 60%, respectively. Inhaled CSD/TL-RP could attenuate antigen-induced inflammatory events in rats, as evidenced by histochemical analyses and inflammatory biomarkers such as lactate dehydrogenase, eosinophil peroxidase, and myeloperoxidase. The CSD/TL-RP seemed to be more potent than the physical mixture in inhibiting inflammatory responses, possibly due to the improved dissolution behavior. Systemic exposure of TL after intratracheal administration of CSD/TL-RP at a pharmacologically effective dose (100 μg of TL/rat) was found to be fivefold less than that of the oral TL dosage form at clinical dose (1.67 mg/kg). Given the improved pharmacodynamics and lower systemic TL concentration, the inhalable TL formulation might provide an interesting alternative to oral therapy with a better safety margin for the treatment of asthma and other airway inflammatory diseases.

Formulation design and in vivo evaluation of dry powder inhalation system of new vasoactive intestinal peptide derivative ([R(15, 20, 21), L(17), A(24,25), des-N(28)]-VIP-GRR) in experimental asthma/COPD model rats

Vasoactive intestinal peptide (VIP) has been considered as a promising drug candidate for asthma and COPD because of its potent immunomodulating and anti-inflammatory activities. Recently, our group developed a new VIP derivative, [R(15, 20, 21), L(17), A(24,25), des-N(28)]-VIP-GRR (IK312548), with improved chemical and metabolic stability. In the present study, a dry powder inhaler system of IK312548 was designed for inhalation therapy with minimal systemic side effects, the physicochemical properties of which were also evaluated with a focus on morphology, particle size distribution, inhalation performance, and peptide stability. Laser diffraction and cascade impactor analysis suggested high dispersion and deposition in the respiratory organs with a fine particle fraction of 31.2%. According to UPLC/ESI-MS and circular dichroic spectral analyses, no significant changes in the purity and structure of VIP derivative were observed during preparation of respirable formulation. Anti-inflammatory properties of IK312548 respirable powder (RP) were characterized in antigen-sensitized asthma/COPD-model rats. There were marked inflammatory cells infiltrated into the lung tissues of experimental asthma/COPD-model rats; however, intratracheal administration of IK312548-RP led to significant reductions of recruited inflammatory cells in lung tissues and BALF by 72 and 78%, respectively. Thus, respirable powder formulation of IK312548 might be a promising medication for asthma, COPD, and other airway inflammatory diseases.

New pharmacotherapy for airway mucus hypersecretion in asthma and COPD: targeting intracellular signaling pathways

Airway mucus hypersecretion is a pathophysiological feature of asthma and chronic obstructive pulmonary disease (COPD). The hypersecretion is associated with phenotypic changes in the airways, notably, increases in the number of surface epithelial goblet cells (hyperplasia) and in the size of the submucosal glands (hypertrophy). The hyperplasia and hypertrophy are associated with increased production of mucin, the gel-forming component of mucus. The excess mucus production contributes to morbidity and mortality in many patients, particularly in those with more severe disease. Although current pharmacotherapy is effective in clinical management of patients with stable asthma, severe asthma is poorly treated and there is no current drug treatment for COPD. In neither disease is there specific, effective pharmacotherapy for the hypersecretion. Consequently, identification of potential drug targets for treatment of hypersecretion in asthma and COPD is warranted. The inflammatory mediators and the associated intracellular signaling pathways underlying upregulation of mucin synthesis and development of goblet cell hyperplasia are gradually being elucidated. These include Th2 cytokines (predominantly IL-9 and IL-13), and IL-1 beta, tumor necrosis factor-alpha (TNF-alpha) and cyclooxygenase (COX)-2. IL-9 may act predominantly via calcium-activated chloride channels (CLCA), IL-13 via STAT-6 and FOXA2, TNF-alpha via NF-kappaB, and IL-1 beta via COX-2. Epidermal growth factor receptor (EGF-R) signaling and FOXA2 appear to be convergent intracellular pathways for a number of inflammatory mediators, with EGF-R upregulated in the airways of asthmatic and COPD patients. Thus, preclinical studies have clearly identified a number of intracellular signaling pathways as possible targets for pharmacotherapy of airway mucus hypersecretion in asthma and COPD. Of these, the EGF-R and Th2 cytokine pathways may have the greatest potential for inhibition of excessive mucus production. However, because these targets are so often intimately involved with different aspects of airway (and systemic) homeostasis, there is potential for development of unwanted side effects with drug intervention. Thus, translation of the promising preclinical studies to the clinic will depend on development of drug moieties with low off-target activity. This may be accomplished by maximizing airway selectivity, which may be facilitated by appropriate delivery device design.

Remodeling in asthma and COPD--differences and similarities

BACKGROUND

Asthma and chronic obstructive pulmonary disease (COPD) are both inflammatory disorders. Diagnosis of these diseases is based upon limitation of expiratory airflow. The pathophysiological correlates to this impaired lung function are complex but they are associated with the development of structural changes in the airways and lung parenchyma. These remodeling processes differ between the two diseases. In asthma, airways obstruction is predominately located in the large airways, although recent studies indicate that inflammation and structural changes also is present in other compartments of the lungs. In COPD, remodeling of the small airways and lung parenchyma are the main correlates to the limitation of expiratory airflow. However, both asthma and COPD are heterogeneous disorders including various phenotypes and there is a considerable overlap between the two diseases.

METHODS AND RESULTS

In the present review, airway remodeling in asthma and COPD will be discussed in three different compartments of the airways: large airways, small airways and lung parenchyma. Different inflammatory cells will be mentioned, as well as markers of remodeling.

CONCLUSION

In COPD and severe asthma, current anti-inflammatory pharmacotherapy does not restore lung function impairment fully. It is therefore recognized that research aiming to explore mechanisms of airway remodeling should be encouraged.

Involvement of IL-13 in tobacco smoke-induced changes in the structure and function of rat intrapulmonary airways

Chronic obstructive pulmonary disease (COPD) involves disease of small airways with an increase in airway smooth muscle sensitivity to spasmogens and with structural changes described as airway remodeling. We investigated the effect of tobacco smoke (TS) exposure on the structure and function of small airways in rats and the role of IL-13 in this response. Precision-cut lung slices (230-280 microm) were prepared from male Sprague-Dawley rats after acute (3 d) or chronic (8 or 16 wk) daily exposure to TS or air. Carbachol (CCh) and 5-hydroxytryptamine (5HT) concentration responses were performed on airways (50-400 microm diameter). The effect of IL-13 in vitro on small airway sensitivity to CCh and 5HT was also determined. Acute exposure to TS did not affect the sensitivity of the intrapulmonary airways to either spasmogen. After 8 weeks of TS exposure, airway hyperresponsiveness (AHR) to CCh was evident (log EC(50) CCh: air = 0.22 microM; TS = -0.12 microM; P = 0.019); AHR to 5HT was also observed after the 16-week exposure to TS (air = -0.85 microM; TS = -1.06 microM; P = 0.038). Chronic TS exposure increased airway wall SMA content, which correlated with increased expression of IL-13 and transforming growth factor (TGF)-beta(1) in the lung tissues. In vitro incubation with IL-13, but not TGF-beta(1), induced changes in small airway sensitivity to CCh and 5HT. Chronic TS exposure induces increased responsiveness in intrapulmonary airways of rats that may be mediated in part by an increase in IL-13.

Mucus hypersecretion in asthma: intracellular signalling pathways as targets for pharmacotherapy

PURPOSE OF REVIEW

Airway mucus hypersecretion is a pathophysiological feature of asthma and, in many patients, contributes to morbidity and mortality. Although current pharmacotherapy is effective in patients with stable disease, severe asthma is poorly treated, and there is no specific treatment for the hypersecretion. Consequently, identification of potential targets for pharmacotherapy of hypersecretion in asthma is warranted. This review identifies intracellular signalling pathways as rational targets for treatment of excessive airway mucus production.

RECENT FINDINGS

The inflammatory mediators and the associated intracellular signalling pathways underlying development of goblet cell hyperplasia, an index of mucus hypersecretion, are becoming ever clearer, and include T-helper type 2 (Th2) cytokines, in particular interleukin (IL)-9 and IL-13, as well as IL-1beta, tumour necrosis factor (TNF)-alpha and cyclooxygenase (COX)-2. IL-9 may act predominantly via calcium-activated chloride channels (CLCAs), IL-13 via STAT-6 and FOXA2, TNF-alpha via nuclear factor (NF)-kappaB, and IL-1beta via COX-2. Epidermal growth factor receptor (EGF-R) and FOXA2 appear to be convergent pathways for a number of mediator signals, with EGF-R up-regulated in the airways of asthmatic patients.

SUMMARY

Although many potential intracellular signalling pathways have been identified as possible targets for pharmacotherapy of airway mucus hypersecretion in asthma, the EGF-R and Th2 cytokine pathways offer the greatest potential for inhibition of excessive mucus production.

New treatments for chronic obstructive pulmonary disease and viable formulation/device options for inhalation therapy

Chronic obstructive pulmonary disease (COPD) is an increasingly important cause of morbidity and mortality, pathological features of which are pulmonary inflammation and irreversible airflow obstruction. Current therapies for COPD are aimed at improvement of clinical symptoms and reduction of inflammation in the respiratory systems. There is a pressing need for the development of new COPD medication, particularly as no existing treatment has been shown to reduce disease progression. In spite of a better understanding of the underlying disease process, there have been limited advances in the drug therapy of COPD, in contrast to the enormous advances in asthma management. Several new therapeutic targets and strategies have been proposed, and new drug candidates, including bronchodilators, protease inhibitors anti-inflammatory drugs and mediator antagonists, are now in clinical development for COPD treatment. New dry powder inhaler (DPI) systems for inhaled COPD therapy have also been developed to maximize drug concentrations in the airway systems, while minimizing systemic exposure and associated toxicity. This article aims to review recent developments in COPD drugs and the delivery systems for inhalation therapy, with particular emphasis on device options and formulations of DPI systems.

Adenosine and osteopontin contribute to the development of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major health concern. Adenosine, a signaling molecule generated in response to cell stress, contributes to the pathogenesis of COPD. An established model of adenosine-mediated lung injury is the adenosine deaminase-deficient (Ada(-/-)) mouse. Osteopontin (OPN) is a chemokine that is produced following injury and is implicated in a variety of human pathologies, but its expression and role in the pathogenesis of COPD have not been examined. To investigate the role of OPN in a model of COPD, Ada(-/-) double-knockout mice were generated, and inflammation and air-space enlargement endpoints were examined. Results demonstrate that Ada(-/-) mice exhibit OPN-dependent neutrophilia, alveolar air-space enlargement, and increases in mediators of air-space enlargement. Furthermore, we demonstrate that patients with COPD have increased OPN expression within distal airways in association with clinical airway obstruction. These results suggest that OPN represents a novel biomarker and therapeutic target for patients with COPD.

Irreversible airway obstruction in asthma

Asthma is generally characterized by fully reversible airway obstruction. However, a significant proportion of asthma patients demonstrate an incomplete reversibility of airway obstruction (IRAO) despite optimal treatment and the absence of a significant smoking history. Such partially irreversible airway obstruction may be due to residual airway inflammation, particularly of the eosinophilic type, and structural changes. Risks factors for IRAO include reduced pulmonary function early in life, frequent exacerbations, smoking, continuing exposure to a sensitizing agent, and adult-onset asthma. IRAO is associated with increased disease severity and increased asthma-related morbidity and mortality. Optimal asthma control, including prevention of asthma exacerbations, smoking avoidance, and sufficient anti-inflammatory therapy, should be implemented in an effort to avoid an accelerated decline in lung function and the development or worsening of IRAO.

Molecular pathogenesis of emphysema

Emphysema is one manifestation of a group of chronic, obstructive, and frequently progressive destructive lung diseases. Cigarette smoking and air pollution are the main causes of emphysema in humans, and cigarette smoking causes emphysema in rodents. This review examines the concept of a homeostatically active lung structure maintenance program that, when attacked by proteases and oxidants, leads to the loss of alveolar septal cells and airspace enlargement. Inflammatory and noninflammatory mechanisms of disease pathogenesis, as well as the role of the innate and adaptive immune systems, are being explored in genetically altered animals and in exposure models of this disease. These recent scientific advances support a model whereby alveolar destruction resulting from a coalescence of mechanical forces, such as hyperinflation, and more recently recognized cellular and molecular events, including apoptosis, cellular senescence, and failed lung tissue repair, produces the clinically recognized syndrome of emphysema.

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.

Bronchodilator response to adrenergic beta2-agonists: relationship to symptoms in an adult community

BACKGROUND

Wheeze and chest tightness has traditionally been associated with enhanced bronchial responsiveness. However, no community studies are available on the associations between bronchodilator response and respiratory symptoms among adults.

AIM

To examine how respiratory symptoms predict bronchodilator response.

METHODS

An age and gender stratified random sample of all adults aged 47-48 and 71-73 years in Bergen, Norway, were invited. The 3506 participants (69%) filled in questionnaires including nine symptoms and performed bronchodilator reversibility tests. Subjects without current anti-asthmatic medication performing acceptable reversibility tests were included in the analyses (n=3088).

RESULTS

A reversibility with FEV(1) increase 12% and 200 ml was obtained in 2% of middle-aged and 4% of elderly subjects (p=0.001). In multiple linear regression analysis bronchodilatation was positively associated with wheezing without cold (FEV(1) increase of 1.5%, 95% CI: (0.9, 2.2)% in all participants and 31 ml, 95% CI: (1, 61)ml in men only) and dyspnoea climbing two flights of stairs (0.9%, 95% CI: (0.5,1.4)% and 12 ml, 95% CI: (1,23)ml). Chronic cough predicted the response negatively (-0.7%, 95% CI: (-1.3,-0.1)% and -17 ml, 95% CI: (-32,-2)ml). In multiple logistic regression analysis morning cough predicted an FEV(1) increase 12% and 200 ml (OR: 1.8, 95% CI: (1.1,2.8)).

CONCLUSIONS

A small fraction of adults in a general population has bronchodilatation after salbutamol inhalation. "Wheezing without cold", "dyspnoea climbing two flights of stairs", and "morning cough" predict an increased bronchodilator response among subjects without current anti-asthmatic medications.

Severe, early-onset emphysema with normal alphal-antitrypsin levels in nonsmokers: a clinical dilemma

Approximately 85% of all cases of chronic obstructive pulmonary disease are attributed to cigarette smoking. The only other established risk factor for the development of chronic obstructive pulmonary disease that is of comparable importance is the deficiency of alpha1-antitrypsin, a rare genetic defect that is present in less than 1% of all cases. Other risk factors are not well characterized in the literature. This article describes one patient without a significant smoking history and with a normal alphaa-antitrypsin level who developed severe early-onset emphysema and gives a brief discussion about other genetic and environmental risk factors for the development of emphysema.

Inhibitory effect of p38 mitogen-activated protein kinase inhibitors on cytokine release from human macrophages

BACKGROUND AND PURPOSE

Macrophages release cytokines that may contribute to pulmonary inflammation in conditions such as chronic obstructive pulmonary disease. Thus, inhibition of macrophage cytokine production may have therapeutic benefit. p38 MAPK may regulate cytokine production, therefore, the effect of two p38 MAPK inhibitors, SB239063 and SD-282, on the release of TNF-alpha, GM-CSF and IL-8 from human macrophages was investigated.

EXPERIMENTAL APPROACH

Cytokine release was measured by ELISA. Immunoblots and mRNA expression studies were performed to confirm p38 MAPK isoform expression and activity. Macrophages were isolated from lung tissue of current smokers, ex-smokers and emphysema patients and exposed to lipopolysaccharide. These cells then released cytokines in a concentration-dependent manner.

KEY RESULTS

SB239063 only inhibited TNF-alpha release (EC50 0.3 +/- 0.1 microM). Disease status had no effect on the efficacy of SB239063. SD-282 inhibited both TNF-alpha and GM-CSF release from macrophages (EC50 6.1 +/- 1.4 nM and 1.8 +/- 0.6 microM respectively) but had no effect on IL-8 release. In contrast, both inhibitors suppressed cytokine production in monocytes.

CONCLUSIONS AND IMPLICATIONS

The differential effects of p38 MAPK inhibitors between macrophages and monocytes could not be explained by differences in p38 MAPK isoform expression or activity. However, the stability of TNF-alpha mRNA was significantly increased in macrophages compared to monocytes. These data suggest a differential involvement for p38 MAPK in macrophage cytokine production compared with monocytes. These effects are not due to lack of p38 activation or p38alpha expression in macrophages but may reflect differential effects on the stability of cytokine mRNA.

Corticosteroids and adrenoceptor agonists: the compliments for combination therapy in chronic airways diseases

The combination of inhaled corticosteroids and long-acting beta2-adrenoceptor agonists is increasingly used as maintenance therapy in patients with moderate to severe asthma or chronic obstructive pulmonary disease (COPD). The main effect of inhaled corticosteroids is thought to be mediated through suppression of airway inflammation, while long-acting beta2-adrenoceptor agonists are thought to work by inducing bronchodilation. However, there is emerging data to indicate that these two classes of drugs interact positively with each other, leading to added or perhaps synergistic benefits for patients. Corticosteroids enhance the expression of beta2-adrenoceptor, thus providing protection against desensitization and development of tolerance to beta2-adrenoceptor agonists, which may occur with prolonged use of these medications. Long-acting beta2-adrenoceptor agonists, on the other hand, may amplify the anti-inflammatory effects of corticosteroids by accelerating nuclear translocation of the glucocorticoid receptor complex, and enhancing transcription and expression of steroid-inducible genes in pro-inflammatory cells. In clinical trials, corticosteroids in combination with long-acting beta2-adrenoceptor agonists reduce exacerbation rates, and improve lung function and health status of patients with moderate to severe asthma or COPD beyond that achieved by individual component therapy. Their effects on mortality are unknown. There is a large clinical trial currently underway, which will provide mortality data by the year 2006. On balance, clinical evidence supports the use of combination therapy in moderate to severe asthma and COPD.

Treatment of airway mucus hypersecretion

Airway mucus hypersecretion is now recognized as a key pathophysiological feature in many patients with asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis. Consequently, it is important to develop drugs that inhibit mucus hypersecretion in these susceptible patients. Conventional therapies, including anticholinergics, ss2-adrenoceptor agonists, corticosteroids, mucolytics and macrolide antibiotics, have variable efficacy in inhibiting airway mucus hypersecretion, and are less effective in COPD than in asthma. Novel pharmacotherapeutic targets are being investigated, including inhibitors of nerve activity (e.g. large conductance calcium-activated potassium, BKCa, channel activators), tachykinin receptor antagonists, epoxygenase inducers (e.g. benzafibrate), inhibitors of mucin exocytosis (e.g. anti-myristoylated alanine-rich C kinase substrate (MARCKS), peptide and Munc-18B blockers), inhibitors of mucin synthesis and goblet cell hyperplasia (e.g. epidermal growth factor (EGF), receptor tyrosine kinase inhibitors, p38 mitogen-activated protein (MAP), kinase inhibitors, MAP kinase kinase/extracellular signal-regulated kinase (MEK/ERK), inhibitors, human calcium-activated chloride (hCACL2), channel blockers and retinoic acid receptor-a antagonists), inducers of goblet cell apoptosis (e.g. Bax inducers or Bcl-2 inhibitors), and purinoceptor P(2Y2) antagonists to inhibit mucin secretion or P(2Y2) agonists to hydrate secretions. However, real and theoretical differences delineate the mucus hypersecretory phenotype in asthma from that in COPD. More information is required on these differences to identify specific therapeutic targets which, in turn, should lead to rational design of anti-hypersecretory drugs for treatment of airway mucus hypersecretion in asthma and COPD.

Chronic cough due to chronic bronchitis: ACCP evidence-based clinical practice guidelines

BACKGROUND

Chronic bronchitis is a disease of the bronchi that is manifested by cough and sputum expectoration occurring on most days for at least 3 months of the year and for at least 2 consecutive years when other respiratory or cardiac causes for the chronic productive cough are excluded. The disease is caused by an interaction between noxious inhaled agents (eg, cigarette smoke, industrial pollutants, and other environmental pollutants) and host factors (eg, genetic and respiratory infections) that results in chronic inflammation in the walls and lumen of the airways. As the disease advances, progressive airflow limitation occurs, usually in association with pathologic changes of emphysema. This condition is called COPD. When a stable patient experiences a sudden clinical deterioration with increased sputum volume, sputum purulence, and/or worsening of shortness of breath, this is referred to as an acute exacerbation of chronic bronchitis as long as conditions other than acute tracheobronchitis are ruled out. The purpose of this review is to present the evidence for the diagnosis and treatment of cough due to chronic bronchitis, and to make recommendations that will be useful for clinical practice.

METHODS

Recommendations for this section of the review were obtained from data using a National Library of Medicine (PubMed) search dating back to 1950, performed in August 2004, of the literature published in the English language. The search was limited to human studies, using the search terms "cough," "chronic bronchitis," and "COPD."

RESULTS

The most effective way to reduce or eliminate cough in patients with chronic bronchitis and persistent exposure to respiratory irritants, such as personal tobacco use, passive smoke exposure, and workplace hazards is avoidance. Therapy with a short-acting inhaled beta-agonist, inhaled ipratropium bromide, and oral theophylline, and a combined regimen of inhaled long-acting beta-agonist and an inhaled corticosteroid may improve cough in patients with chronic bronchitis, but there is no proven benefit for the use of prophylactic antibiotics, oral corticosteroids, expectorants, postural drainage, or chest physiotherapy. For the treatment of an acute exacerbation of chronic bronchitis, there is evidence that inhaled bronchodilators, oral antibiotics, and oral corticosteroids (or in severe cases IV corticosteroids) are useful, but their effects on cough have not been systematically evaluated. Therapy with expectorants, postural drainage, chest physiotherapy, and theophylline is not recommended. Central cough suppressants such as codeine and dextromethorphan are recommended for short-term symptomatic relief of coughing.

CONCLUSIONS

Chronic bronchitis due to cigarette smoking or other exposures to inhaled noxious agents is one of the most common causes of chronic cough in the general population. The most effective way to eliminate cough is the avoidance of all respiratory irritants. When cough persists despite the removal of these inciting agents, there are effective agents to reduce or eliminate cough.

Adenosine-dependent pulmonary fibrosis in adenosine deaminase-deficient mice

Pulmonary fibrosis is a common feature of numerous lung disorders, including interstitial lung diseases, asthma, and chronic obstructive pulmonary disease. Despite the prevalence of pulmonary fibrosis, the molecular mechanisms governing inflammatory and fibroproliferative aspects of the disorder are not clear. Adenosine is a purine-signaling nucleoside that is generated in excess during cellular stress and damage. This signaling molecule has been implicated in the regulation of features of chronic lung disease; however, the impact of adenosine on pulmonary fibrosis is not well understood. The goal of this study was to explore the impact of endogenous adenosine elevations on pulmonary fibrosis. To accomplish this, adenosine deaminase (ADA)-deficient mice were treated with various levels of ADA enzyme replacement therapy to regulate endogenous adenosine levels in the lung. Maintaining ADA-deficient mice on low dosages of ADA enzyme therapy led to chronic elevations in lung adenosine levels that were associated with pulmonary inflammation, expression of profibrotic molecules, collagen deposition, and extreme alteration in airway structure. These features could be blocked by preventing elevations in lung adenosine. Furthermore, lowering lung adenosine levels after the establishment of pulmonary fibrosis resulted in a resolution of fibrosis. These findings demonstrate that chronic adenosine elevations are associated with pulmonary fibrosis in ADA-deficient mice and suggest that the adenosine functions as a profibrotic signal in the lung.

Determining the functional role of TRPC channels in primary cells

Although the TRPC members of the mammalian transient receptor potential TRP cation channel family were the first to be described in 1995, the depth of knowledge of TRPC channels has fallen behind that of their counterparts in the TRPV and TRPM subfamilies in the intervening years. The complexities and controversies of TRPC channel composition and regulation have hindered their progress as therapeutic targets in the drug discovery environment to date, however embracing these challenges as opportunities may bring TRPC channels to the forefront of the discovery of novel therapies for many diseases. These challenges and opportunities of exploring TRPC channels as therapeutic targets are highlighted and discussed in this review with respect to respiratory diseases.

How representative are clinical study patients with asthma or COPD for a larger "real life" population of patients with obstructive lung disease?

Evidence-based medicine is a corner stone in treatment decision making and large randomised, clinical trials are usually designed in order to provide highly significant results. This study was conducted in order to find out to what extend a "real life" patient population with obstructive lung disease could fit into criteria commonly used in clinical research trials. As a secondary aim of the study, we wanted to compare the OLD population recruited from GP's and specialist outpatient clinics, respectively. Eight-hundred and seventy prospective OLD patients were included. Criteria's for selecting asthma patients to a clinical trial were, absence of co-morbidity, FEV 50-85% of predicted, present or historical reversibility 12% last year, non-smoke or if ex-smoke a smoke burden less then 10 pack years. Only 5.4% of the study asthma patients met with these criteria. Additional criteria as being symptomatic and regular use of inhaled corticosteroids reduced the numbers of eligible asthma patients to 3.3% representing 1.3% of the entire population. The same procedure was applied for the COPD patients, requesting a FEV1 <70% of predicted normal, significant smoke history (>15 pack years) and absence of atopy. This selected 17% of the COPD population, representing 7% of the entire population. We conclude that "evidence based" treatment decisions for OLD are based on studies which include a very small and highly selected fraction of this patient population. It is questionable whether such data can extrapolated to a larger, "real life" population of patients with obstructive lung disease. Moreover, we found surprisingly minor differences between the Specialist and GP populations.

Cathepsin K: a cysteine protease with unique kinin-degrading properties

Taking into account a previous report of an unidentified enzyme from macrophages acting as a kininase, the ability of cysteine proteases to degrade kinins has been investigated. Wild-type fibroblast lysates from mice, by contrast with cathepsin K-deficient lysates, hydrolysed BK (bradykinin), and released two metabolites, BK-(1-4) and BK-(5-9). Cathepsin K, but not cathepsins B, H, L and S, cleaved kinins at the Gly4-Phe5 bond and the bradykinin-mimicking substrate Abz (o-aminobenzoic acid)-RPPGFSPFR-3-NO2-Tyr (3-nitrotyrosine) more efficiently (pH 6.0: kcat/K(m)=12500 mM(-1) x s(-1); pH 7.4: kcat/K(m)=6930 mM(-1) x s(-1)) than angiotensin-converting enzyme hydrolysed BK. Conversely Abz-RPPGFSPFR-3-NO2-Tyr was not cleaved by the Y67L (Tyr67-->Leu)/L205A (Leu205-->Ala) cathepsin K mutant, indicating that kinin degradation mostly depends on the S2 substrate specificity. Kininase activity was further evaluated on bronchial smooth muscles. BK, but not its metabolites BK(1-4) and BK(5-9), induced a dose-dependent contraction, which was abolished by Hoe140, a B2-type receptor antagonist. Cathepsin K impaired BK-dependent contraction of normal and chronic hypoxic rats, whereas cathepsins B and L did not. Taking together vasoactive properties of kinins and the potency of cathepsin K to modulate BK-dependent contraction of smooth muscles, the present data support the notion that cathepsin K may act as a kininase, a unique property among mammalian cysteine proteases.

The pathophysiology of airway dysfunction

Asthma and chronic obstructive pulmonary disease (COPD) are distinct inflammatory disorders with differing pathophysiologic mechanisms, different clinical courses, and, therefore, distinct treatment strategies. Whereas in asthma airflow limitation is typically episodic and reversible, airflow limitation in COPD is progressive and only partially reversible. In contrast to asthma, which is characterized by an elevated number of eosinophils in the blood and the accumulation of elevated numbers of activated eosinophils, mast cells, and CD4+ T(H)2-lymphocytes in the lungs, the primary inflammatory cells present in the lungs of patients with stable COPD are neutrophils, macrophages, and CD8+ lymphocytes. Bronchoconstriction in COPD is largely regulated by cholinergically mediated vagal tone, and the pathologic processes of COPD further reduce airway patency. Bronchodilators, most notably anticholinergics, are recommended as first-line pharmacologic therapy for COPD. Proper use of inhaled anticholinergic medications has been shown to lead to significant reversibility of acetylcholine-mediated bronchoconstriction during both stable disease and exacerbations of COPD. For patients with asthma, current guidelines recommend anti-inflammatory medications, specifically inhaled corticosteroids and leukotriene-modifiers, as first-line therapy, making these agents the mainstay of asthma therapy. In contrast, the current guidelines for COPD management recommend that inhaled anti-inflammatory agents be tried in patients with COPD only as second-line therapy for patients who have severe to very severe airflow obstruction with frequent exacerbations and who remain symptomatic despite maximized bronchodilation with multiple inhaled bronchodilators. Hence, it is extremely important to understand the differences between the underlying pathogenesis and pathophysiology of COPD and those of asthma, as these differences dictate the implementation of distinctly different treatment options for these 2 diseases.

Marked Up-regulation of T Lymphocytes and Expression of Interleukin-9 in Bronchial Biopsies From Patients With Chronic Bronchitis With Obstruction *

STUDY OBJECTIVE

To examine the differences in the inflammatory cell and cytokine profile between patients with chronic bronchitis (CB) with and without airway obstruction compared to control subjects.

DESIGN

We used bronchial biopsy samples from the patients and control subjects and analyzed them for the presence of CD3 T cells, CD68, major basic protein (MBP), elastase, and tryptase, as well as expression of messenger RNA (mRNA) coding for interleukin (IL)-4, IL-5, interferon (IFN)-gamma, IL-9, eotaxin, and IFN-gamma-inducible protein (IP)-10. The techniques of immunocytochemistry and in situ hybridization were used. Results were expressed as the number of immunoreactive and mRNA-positive cells per field.

RESULTS

Increased number of elastase, CD68, and MBP-positive cells (n = 9, p < 0.01) was demonstrated in both groups of patients with CB compared to control subjects. In patients with CB and obstruction, the number of elastase, CD68, and the number of CD3-positive cells was significantly increased compared to patients with CB without obstruction (n = 9, p < 0.01). IFN-gamma mRNA expression was increased in both groups of patients with CB compared to control subjects (n = 9, p < 0.01). IL-9 mRNA was significantly increased only in patients with CB and obstruction (n = 9, p < 0.01). Co-localization studies demonstrated > 80% of all IL-9-positive cells to be CD3-positive T cells. IP-10 mRNA was significantly increased in both groups of patients with CB compared to control subjects (n = 9, p < 0.01).

CONCLUSIONS

These results indicate a differential expression of inflammatory markers and cytokine mRNA in patients with obstructive CB. Increased presence of T lymphocytes and up-regulation of IL-9 and IP-10 mRNA expression in the bronchial biopsy samples may contribute to the airway obstruction in these patients.

Nasal neutrophil activity and mucinous secretory responsiveness in COPD

Patients with chronic obstructive pulmonary disease (COPD) frequently report nasal symptoms. In the present study, we have examined whether or not COPD is associated with any nasal inflammation. Plasma exudation evoked by histamine challenges has been employed to improve the recovery of inflammatory indices in nasal lavage fluids. In 23 COPD-patients and 26 healthy subjects, all without history or signs of allergic rhinitis, nasal polyposis, or chronic rhinosinusitis, nasal saline-lavages were performed with and without histamine. alpha2-Macroglobulin, fucose, eosinophil cationic protein (ECP) and myeloperoxidase (MPO) were determined as indices of plasma exudation, mucinous secretion, eosinophil activity and neutrophil activity, respectively. The difference in MPO-levels between the histamine and the saline lavage was greater in COPD patients compared with healthy subjects (P<0.05). Also, COPD patients reporting nasal symptoms presented an increase in MPO at histamine challenge (P<0.05, cf. saline) and greater differences in MPO and fucose, respectively, between the histamine and the saline lavage (P<0.05, cf. patients without symptoms). We conclude that COPD is not associated with any marked nasal inflammation. However, our observation on increased MPO-levels at histamine challenge suggests some degree of increased neutrophil activity in this condition. Furthermore, when associated with nasal symptoms, COPD may be associated with an increased nasal secretory responsiveness.

Keratinocyte growth factor (KGF) decreases ICAM-1 and VCAM-1 cell expression on bronchial epithelial cells

Activation of leucocytes during airway inflammatory reaction involves adhesion to bronchial epithelial cells (BEC), a process implicating specific interactions between glycoproteins with epithelial cell surface proteins, mainly intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). In this study, the effect of keratinocyte growth factor (KGF), a growth factor involved in pulmonary epithelium repair, was evaluated on adhesion molecule expression with BEAS-2B cells and BEC and granulocyte adherence to BEAS-2B. The modulation by KGF of membrane and mRNA expression of ICAM-1 and VCAM-1 was studied on confluent cells stimulated or not with tumour necrosis factor-alpha (TNF) (200 UI/ml) or TNF and interleukin (IL)-4 (50 UI/ml and 10 ng/ml). Levels of soluble-(s)ICAM-1 and sVCAM-1 were measured by ELISA. Although moderately, KGF significantly decreased membrane ICAM-1 expression in unstimulated BEAS-2B cells (24% inhibition at 100 ng/ml) or in TNF- or TNF + IL-4-stimulated cells (22.5 and 18.7% inhibition, respectively). Treatment with KGF tended to decrease VCAM-1 expression in TNF- and TNF + IL-4-stimulated BEAS-2B (P = n.s. and P < 0.05, 14 and 15% inhibition, respectively). In primary culture of BEC, adhesion molecule expression was also reduced. ICAM-1 and VCAM-1 mRNA expression were also inhibited by KGF. Levels of sICAM-1 and sVCAM-1 were not significantly increased in supernatants from KGF-treated cells (30% and 24% increase at 100 ng/ml, respectively) compared to controls. Moreover, KGF decreased by 31% the adherence of neutrophils to TNF-activated BEAS-2B. In conclusion, KGF decreases ICAM-1 and VCAM-1 expression and neutrophil adherence in BEC. These suggest its involvement in the resolution of the inflammatory reaction.

Kininogen-derived peptides for investigating the putative vasoactive properties of human cathepsins K and L

Macrophages at an inflammatory site release massive amounts of proteolytic enzymes, including lysosomal cysteine proteases, which colocalize with their circulating, tight-binding inhibitors (cystatins, kininogens), so modifying the protease/antiprotease equilibrium in favor of enhanced proteolysis. We have explored the ability of human cathepsins B, K and L to participate in the production of kinins, using kininogens and synthetic peptides that mimic the insertion sites of bradykinin on human kininogens. Although both cathepsins processed high-molecular weight kininogen under stoichiometric conditions, only cathepsin L generated significant amounts of immunoreactive kinins. Cathepsin L exhibited higher specificity constants (kcat/Km) than tissue kallikrein (hK1), and similar Michaelis constants towards kininogen-derived synthetic substrates. A 20-mer peptide, whose sequence encompassed kininogen residues Ile376 to Ile393, released bradykinin (BK; 80%) and Lys-bradykinin (20%) when incubated with cathepsin L. By contrast, cathepsin K did not release any kinin, but a truncated kinin metabolite BK(5-9) [FSPFR(385-389)]. Accordingly cathepsin K rapidly produced BK(5-9) from bradykinin and Lys-bradykinin, and BK(5-8) from des-Arg9-bradykinin, by cleaving the Gly384-Phe385 bond. Data suggest that extracellular cysteine proteases may participate in the regulation of kinin levels at inflammatory sites, and clearly support that cathepsin K may act as a potent kininase.