Staphylococcus aureus Small-Colony Variants from Airways of Adult Cystic Fibrosis Patients as Precursors of Adaptive Antibiotic-Resistant Mutations

Prototypic Staphylococcus aureus and their small-colony variants (SCVs) are predominant in cystic fibrosis (CF), but the interdependence of these phenotypes is poorly understood. We characterized S. aureus isolates from adult CF patients over several years. Of 18 S. aureus-positive patients (58%), 13 (72%) were positive for SCVs. Characterization included genotyping, SCCmec types, auxotrophy, biofilm production, antibiotic susceptibilities and tolerance, and resistance acquisition rates. Whole-genome sequencing revealed that several patients were colonized with prototypical and SCV-related clones. Some clonal pairs showed acquisition of aminoglycoside resistance that was not explained by aminoglycoside-modifying enzymes, suggesting a mutation-based process. The characteristics of SCVs that could play a role in resistance acquisition were thus investigated further. For instance, SCV isolates produced more biofilm (p < 0.05) and showed a higher survival rate upon exposure to ciprofloxacin and vancomycin compared to their prototypic associated clones. SCVs also developed spontaneous rifampicin resistance mutations at a higher frequency. Accordingly, a laboratory-derived SCV (ΔhemB) acquired resistance to ciprofloxacin and gentamicin faster than its parent counterpart after serial passages in the presence of sub-inhibitory concentrations of antibiotics. These results suggest a role for SCVs in the establishment of persistent antibiotic-resistant clones in adult CF patients.

Invadosome Formation by Lung Fibroblasts in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by abnormal fibroblast accumulation in the lung leading to extracellular matrix deposition and remodeling that compromise lung function. However, the mechanisms of interstitial invasion and remodeling by lung fibroblasts remain poorly understood. The invadosomes, initially described in cancer cells, consist of actin-based adhesive structures that coordinate with numerous other proteins to form a membrane protrusion capable of degrading the extracellular matrix to promote their invasive phenotype. In this regard, we hypothesized that invadosome formation may be increased in lung fibroblasts from patients with IPF. Public RNAseq datasets from control and IPF lung tissues were used to identify differentially expressed genes associated with invadosomes. Lung fibroblasts isolated from bleomycin-exposed mice and IPF patients were seeded with and without the two approved drugs for treating IPF, nintedanib or pirfenidone on fluorescent gelatin-coated coverslips for invadosome assays. Several matrix and invadosome-associated genes were increased in IPF tissues and in IPF fibroblastic foci. Invadosome formation was significantly increased in lung fibroblasts isolated from bleomycin-exposed mice and IPF patients. The degree of lung fibrosis found in IPF tissues correlated strongly with invadosome production by neighboring cells. Nintedanib suppressed IPF and PDGF-activated lung fibroblast invadosome formation, an event associated with inhibition of the PDGFR/PI3K/Akt pathway and TKS5 expression. Fibroblasts derived from IPF lung tissues express a pro-invadosomal phenotype, which correlates with the severity of fibrosis and is responsive to antifibrotic treatment.

Human Lung Tissue Implanted on the Chick Chorioallantoic Membrane as a Novel In Vivo Model of IPF

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease with no curative pharmacological treatment. Current preclinical models fail to accurately reproduce human pathophysiology and are therefore poor predictors of clinical outcomes. Here, we investigated whether the chick embryo chorioallantoic membrane (CAM) assay supports the implantation of xenografts derived from IPF lung tissue and primary IPF lung fibroblasts and can be used to evaluate the efficacy of antifibrotic drugs. We demonstrate that IPF xenografts maintain their integrity and are perfused with chick embryo blood. Size measurements indicate that the xenografts amplify on the CAM, and Ki67 and pro-collagen type I immunohistochemical staining highlight the presence of proliferative and functional cells in the xenografts. Moreover, the IPF phenotype and immune microenvironment of lung tissues are retained when cultivated on the CAM and the fibroblast xenografts mimic invasive IPF fibroblastic foci. Daily treatments of the xenografts with nintedanib and PBI-4050 significantly reduce their size, fibrosis-associated gene expression, and collagen deposition. Similar effects are found with GLPG1205 and fenofibric acid, two drugs that target the immune microenvironment. Our CAM-IPF model represents the first in vivo model of IPF that uses human lung tissue. This rapid and cost-effective assay could become a valuable tool for predicting the efficacy of antifibrotic drug candidates for IPF.

Bronchiectasis and inhaled tobramycin: A literature review

BACKGROUND

Inhaled antibiotics have been incorporated into contemporary European and British guidelines for bronchiectasis, yet no inhaled antibiotics have been approved in the United States or Europe for the treatment of bronchiectasis not related to cystic fibrosis. Pseudomonas aeruginosa infection is common in patients with bronchiectasis, contributing to a cycle of progressive inflammation, exacerbations, and airway remodelling.

OBJECTIVE

The aim of the current study was to identify and evaluate published studies of inhaled tobramycin solution or powder in patients with bronchiectasis and P. aeruginosa infection not associated with cystic fibrosis.

METHODS

A literature review was conducted utilising the PubMed and Cochrane databases. Studies published in the English language that reported safety and/or efficacy outcomes of inhaled tobramycin either alone or in combination with other antibiotics were included.

RESULTS

Seven clinical trials published between 1999 and 2021 were identified that met inclusion criteria. Inhaled tobramycin therapy was effective in reducing P. aeruginosa microbial density in the sputum of patients with bronchiectasis. Several studies demonstrated favourable impacts on hospitalisations, number and severity of exacerbations, and symptoms. Other studies were underpowered for these clinical outcomes or were exploratory in nature. Although tobramycin was generally well tolerated, some evidence of treatment-associated wheezing was reported.

CONCLUSIONS

In patients with bronchiectasis and chronic P. aeruginosa infection, inhaled tobramycin was effective in reducing the density of bacteria in sputum, which may be associated with additional clinical benefits. Definitive phase 3 trials of inhaled tobramycin in patients with bronchiectasis are indicated to determine clinical efficacy and long-term safety.

New Therapies to Correct the Cystic Fibrosis Basic Defect

Rare diseases affect 400 million individuals worldwide and cause significant morbidity and mortality. Finding solutions for rare diseases can be very challenging for physicians and researchers. Cystic fibrosis (CF), a genetic, autosomal recessive, multisystemic, life-limiting disease does not escape this sad reality. Despite phenomenal progress in our understanding of this disease, treatment remains difficult. Until recently, therapies for CF individuals were focused on symptom management. The discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene and its product, a protein present at the apical surface of epithelial cells regulating ion transport, allowed the scientific community to learn about the basic defect in CF and to study potential therapies targeting the dysfunctional protein. In the past few years, promising therapies with the goal to restore CFTR function became available and changed the lives of several CF patients. These medications, called CFTR modulators, aim to correct, potentialize, stabilize or amplify CFTR function. Furthermore, research is ongoing to develop other targeted therapies that could be more efficient and benefit a larger proportion of the CF community. The purpose of this review is to summarize our current knowledge of CF genetics and therapies restoring CFTR function, particularly CFTR modulators and gene therapy.

Airway Mucins Inhibit Oxidative and Non-Oxidative Bacterial Killing by Human Neutrophils

Neutrophil killing of bacteria is mediated by oxidative and non-oxidative mechanisms. Oxidants are generated through the NADPH oxidase complex, whereas antimicrobial proteins and peptides rank amongst non-oxidative host defenses. Mucus hypersecretion, deficient hydration and poor clearance from the airways are prominent features of cystic fibrosis (CF) lung disease. CF airways are commonly infected by Pseudomonas aeruginosa and Burkholderia cepacia complex bacteria. Whereas the former bacterium is highly sensitive to non-oxidative killing, the latter is only killed if the oxidative burst is intact. Despite an abundance of neutrophils, both pathogens thrive in CF airway secretions. In this study, we report that secreted mucins protect these CF pathogens against host defenses. Mucins were purified from CF sputum and from the saliva of healthy volunteers. Whereas mucins did not alter the phagocytosis of Pseudomonas aeruginosa and Burkholderia cenocepacia by neutrophils, they completely suppressed bacterial killing. Accordingly, mucins markedly inhibited non-oxidative bacterial killing by neutrophil granule extracts, or by lysozyme and the cationic peptide, human β defensin-2 (HBD2). Mucins also suppressed the neutrophil oxidative burst through a charge-dependent mechanism that could be reversed by the cationic aminoglycoside, tobramycin. Our data indicate that airway mucins protect Gram-negative bacteria against neutrophil killing by suppressing the oxidative burst and inhibiting the bactericidal capacity of cationic proteins and peptides. Mucin hypersecretion, dehydration, stasis and anionic charge represent key therapeutic targets for improving host defenses and airway inflammation in CF and other muco-secretory airway diseases.

Despite Antagonism in vitro, Pseudomonas aeruginosa Enhances Staphylococcus aureus Colonization in a Murine Lung Infection Model

Staphylococcus aureus and Pseudomonas aeruginosa are prevalent lung pathogens in cystic fibrosis (CF). Whereas co-infection worsens the clinical outcome, prototypical strains are usually antagonistic in vitro. We sought to resolve the discrepancy between these in vitro and in vivo observations. In vitro, growth kinetics for co-cultures of co-isolates from CF patients showed that not all P. aeruginosa strains affected S. aureus viability. On solid media, S. aureus slow-growing colonies were visualized around some P. aeruginosa strains whether or not S. aureus viability was reduced in liquid co-cultures. The S. aureus-P. aeruginosa interactions were then characterized in a mouse lung infection model. Lung homogenates were plated on selective media allowing colony counts of either bacterium. Overall, 35 P. aeruginosa and 10 S. aureus strains (clinical, reference, and mutant strains), for a total of 200 co-infections, were evaluated. We observed that S. aureus colonization of lung tissues was promoted by P. aeruginosa and even by strains showing antagonism in vitro. Promotion was proportional to the extent of P. aeruginosa colonization, but no correlation was found with the degree of myeloperoxidase quantification (as marker of inflammation) or with specific virulence-associated factors using known mutant strains of S. aureus and P. aeruginosa. On the other hand, P. aeruginosa significantly increased the expression of two possible cell receptors for S. aureus, i.e., ICAM-1 and ITGA-5 (marker for integrin α₅β₁) in lung tissue, while mono-infections by S. aureus did not. This study provides insights on polymicrobial interactions that may influence the progression of CF-associated pulmonary infections.

Cystic Fibrosis: Pathophysiology of Lung Disease

Cystic fibrosis (CF) is a common, life-threatening, multisystemic, autosomal recessive disorder. In the last few years, giant steps have been made with regard to the understanding of CF pathophysiology, allowing the scientific community to propose mechanisms that cause the myriad of CF clinical manifestations. Following the discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in 1989, the structure and function of the CFTR protein were described. Since then, more than 2,000 variants of the CFTR gene and their impact on the amount and function of the CFTR protein have been reported. The role of the CFTR protein as an ion channel transporting chloride and bicarbonate and its repercussions on different epithelial cell-lined organs and mucus are now better understood. Mechanisms behind susceptibility to infection in CF have also been proposed and include abnormalities in the composition, volume and acidity of the airway surface liquid, changes in the submucosal gland's anatomy and function, and deficiencies in the mucociliary clearance system. Numerous hypotheses explaining the excessive inflammatory response in CF are also debated and involve impaired mucociliary clearance, persistent hypoxia, lipid abnormalities, protease and antiprotease disproportion, and oxidant and antioxidant imbalance. The purpose of this review is to summarize our current knowledge of CF pathophysiology, including significant historic discoveries and most recent breakthroughs, and to improve understanding and awareness of this fatal disease.

Antioxidants and Chronic Obstructive Pulmonary Disease

Antioxidants represent an attractive therapeutic avenue for individuals with chronic obstructive pulmonary disease (COPD). Cigarette smoke, the major cause of COPD, contains very high concentrations of gaseous and soluble oxidants that can directly induce cell injury and death. Furthermore, particulate matter in cigarette smoke activates lung macrophages that subsequently attract neutrophils. Both neutrophils and macrophages from the lungs of cigarette smokers continuously release large amounts of superoxide and hydrogen peroxide through the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex. Once individuals with COPD stop smoking, the neutrophilic inflammation in the airways and lung parenchyma persists, as do the markers of oxidative stress. Several animal models of cigarette smoke-induced injury have provided evidence that various antioxidants may prevent inflammation and morphological changes associated with COPD however, evidence of benefit in patients is less abundant. Although oxidants can inactivate alpha-1 antitrypsin and other protective proteins, damage lung tissue, and increase mucus production, they also are essential for killing pathogens and resolving inflammation. This review will examine the pre-clinical and clinical evidence of a role for antioxidants in the therapy of patients with COPD.

The Efficacy of MAG-DHA for Correcting AA/DHA Imbalance of Cystic Fibrosis Patients

Omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementations are thought to improve essential fatty acid deficiency (EFAD) as well as reduce inflammation in Cystic Fibrosis (CF), but their effectiveness in clinical studies remains unknown. The aim of the study was to determine how the medical food containing docosahexaenoic acid monoglyceride (MAG-DHA) influenced erythrocyte fatty acid profiles and the expression levels of inflammatory circulating mediators. We conducted a randomized, double blind, pilot trial including fifteen outpatients with Cystic Fibrosis, ages 18–48. The patients were divided into 2 groups and received MAG-DHA or a placebo (sunflower oil) for 60 days. Patients took 8 × 625 mg MAG-DHA softgels or 8 × 625 mg placebo softgels every day at bedtime for 60 days. Lipid analyses revealed that MAG-DHA increased docosahexaenoic acid (DHA) levels and decrease arachidonic acid (AA) ratio (AA/DHA) in erythrocytes of CF patients following 1 month of daily supplementation. Data also revealed a reduction in plasma human leukocyte elastase (pHLE) complexes and interleukin-6 (IL-6) expression levels in blood samples of MAG-DHA supplemented CF patients. This pilot study indicates that MAG-DHA supplementation corrects erythrocyte AA/DHA imbalance and may exert anti-inflammatory properties through the reduction of pHLE complexes and IL6 in blood samples of CF patients. Trial registration: Pro-resolving Effect of MAG-DHA in Cystic Fibrosis (PREMDIC), NCT02518672.

Cigarette smoke activates CFTR through ROS-stimulated cAMP signaling in human bronchial epithelial cells

Air pollution stimulates airway epithelial secretion through a cholinergic reflex that is unaffected in cystic fibrosis (CF), yet a strong correlation is observed between passive smoke exposure in the home and impaired lung function in CF children. Our aim was to study the effects of low smoke concentrations on cystic fibrosis transmembrane conductance regulator (CFTR) function in vitro. Cigarette smoke extract stimulated robust anion secretion that was transient, mediated by CFTR, and dependent on cAMP-dependent protein kinase activation. Secretion was initiated by reactive oxygen species (ROS) and mediated by at least two distinct pathways: autocrine activation of EP4 prostanoid receptors and stimulation of Ca2+ store-operated cAMP signaling. The response was absent in cells expressing the most common disease-causing mutant F508del-CFTR. In addition to the initial secretion, prolonged exposure of non-CF bronchial epithelial cells to low levels of smoke also caused a gradual decline in CFTR functional expression. F508del-CFTR channels that had been rescued by the CF drug combination VX-809 (lumacaftor) + VX-770 (ivacaftor) were more sensitive to this downregulation than wild-type CFTR. The results suggest that CFTR-mediated secretion during acute cigarette smoke exposure initially protects the airway epithelium while prolonged exposure reduces CFTR functional expression and reduces the efficacy of CF drugs.

Synthesis and Characterization of a Phosphate Prodrug of Isoliquiritigenin

Isoliquiritigenin (1) possesses a variety of biological activities in vitro. However, its poor aqueous solubility limits its use for subsequent in vivo experimentation. In order to enable the use of 1 for in vivo studies without the use of toxic carriers or cosolvents, a phosphate prodrug strategy was implemented relying on the availability of phenol groups in the molecule. In this study, a phosphate group was added to position C-4 of 1, leading to the more water-soluble prodrug 2 and its ammonium salt 3, which possesses increased stability compared to 2. Herein are reported the synthesis, characterization, solubility, and stability of phosphate prodrug 3 in biological medium in comparison to 1, as well as new results on its anti-inflammatory properties in vivo. As designed, the solubility of prodrug 3 was superior to that of the parent natural product 1 (9.6 mg/mL as opposed to 3.9 μg/mL). Prodrug 3 as an ammonium salt was also found to possess excellent stability as a solid and in aqueous solution, as opposed to its phosphoric acid precursor 2.

Bis-Michael Acceptors as Novel Probes to Study the Keap1/Nrf2/ARE Pathway

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a master regulator that promotes the transcription of cytoprotective genes in response to oxidative/electrophilic stress. Various Michael-type compounds were designed and synthesized, and their potency to activate the Keap1/Nrf2/ARE pathway was evaluated. Compounds bearing two Michael-type acceptors proved to be the most active. Tether length and rigidity between the acceptors was crucial. This study will help to understand how this feature disrupts the interaction between Keap1 and Nrf2.

Cystic Fibrosis Transmembrane Conductance Regulator. Implications in Cystic Fibrosis and Chronic Obstructive Pulmonary Disease

Cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD) have traditionally been viewed as two distinct entities of unrelated origins. However, molecular, cellular, and clinical studies have revealed that cystic fibrosis transmembrane conductance regulator (CFTR) protein dysfunction is common to both conditions, one (CF) being defined genetically and the other (COPD) as an acquired CFTR deficiency. Multiple molecular mechanisms of cigarette smoke-induced CFTR dysfunction have been reported. More importantly, considerable evidence of cigarette smoke-induced CFTR dysfunction in several respiratory and nonrespiratory tissues have been confirmed, making CFTR a target that cannot be overlooked in our quest to understand COPD and improve therapies for individuals affected by this disease. This review summarizes the molecular, cellular, and clinical evidence that CFTR dysfunction is induced by cigarette smoke exposure both in vitro and in vivo, and explores how this may contribute to the development of COPD.

Proresolving Action of Docosahexaenoic Acid Monoglyceride in Lung Inflammatory Models Related to Cystic Fibrosis

Cystic fibrosis (CF) is a hereditary, chronic disease of the exocrine glands, characterized by the production of viscid mucus that obstructs the pancreatic ducts and bronchi, leading to infection and fibrosis. ω3 fatty acid supplementations are known to improve the essential fatty acid deficiency as well as reduce inflammation in CF. The objective of this study was to determine the effects of docosahexaenoic acid monoacylglyceride (MAG-DHA) on mucin overproduction and resolution of airway inflammation in two in vitro models related to CF. Isolated human bronchi reverse permeabilized with CF transmembrane conductance regulator (CFTR) silencing (si) RNA and stable Calu3 cells expressing a short hairpin (sh) RNA directed against CFTR (shCFTR) were used. Lipid analyses revealed that MAG-DHA increased DHA/arachidonic acid (AA) ratio in shCFTR Calu-3 cells. MAG-DHA treatments, moreover, resulted in a decreased activation of Pseudomonas aeruginosa LPS-induced NF-κB in CF and non-CF Calu-3 cells. Data also revealed a reduction in MUC5AC, IL-6, and IL-8 expression levels in MAG-DHA-treated shCFTR cells stimulated, or not, with LPS. Antiinflammatory properties of MAG-DHA were also investigated in a reverse-permeabilized human bronchi model with CFTR siRNA. After MAG-DHA treatments, messenger RNA transcript levels for MUC5AC, IL-6, and IL-8 were markedly reduced in LPS-treated CFTR siRNA bronchi. MAG-DHA displays antiinflammatory properties and reduces mucin overexpression in Calu-3 cells and human bronchi untreated or treated with P. aeruginosa LPS, a finding consistent with the effects of resolvinD1, a known antiinflammatory mediator.

Inflammation in cystic fibrosis lung disease: Pathogenesis and therapy

Lung disease is the major cause of morbidity and mortality in patients with cystic fibrosis (CF). Although CF lung disease is primarily an infectious disorder, the associated inflammation is both intense and ineffective at clearing pathogens. Persistent high-intensity inflammation leads to permanent structural damage of the CF airways and impaired lung function that eventually results in respiratory failure and death. Several defective inflammatory responses have been linked to cystic fibrosis transmembrane conductance regulator (CFTR) deficiency including innate and acquired immunity dysregulation, cell membrane lipid abnormalities, various transcription factor signaling defects, as well as altered kinase and toll-like receptor responses. The inflammation of the CF lung is dominated by neutrophils that release oxidants and proteases, particularly elastase. Neutrophil elastase in the CF airway secretions precedes the appearance of bronchiectasis, and correlates with lung function deterioration and respiratory exacerbations. Anti-inflammatory therapies are therefore of particular interest for CF lung disease but must be carefully studied to avoid suppressing critical elements of the inflammatory response and thus worsening infection. This review examines the role of inflammation in the pathogenesis of CF lung disease, summarizes the results of past clinical trials and explores promising new anti-inflammatory options.

Inhibition of influenza virus replication by targeting broad host cell pathways

Antivirals that are currently used to treat influenza virus infections target components of the virus which can mutate rapidly. Consequently, there has been an increase in the number of resistant strains to one or many antivirals in recent years. Here we compared the antiviral effects of lysosomotropic alkalinizing agents (LAAs) and calcium modulators (CMs), which interfere with crucial events in the influenza virus replication cycle, against avian, swine, and human viruses of different subtypes in MDCK cells. We observed that treatment with LAAs, CMs, or a combination of both, significantly inhibited viral replication. Moreover, the drugs were effective even when they were administered 8 h after infection. Finally, analysis of the expression of viral acidic polymerase (PA) revealed that both drugs classes interfered with early events in the viral replication cycle. This study demonstrates that targeting broad host cellular pathways can be an efficient strategy to inhibit influenza replication. Furthermore, it provides an interesting avenue for drug development where resistance by the virus might be reduced since the virus is not targeted directly.

Anti-cancer effects of a new docosahexaenoic acid monoacylglyceride in lung adenocarcinoma

Lung cancer is the leading cause of cancer-related deaths worldwide. Despite advances in research, diagnosis and treatment, lung cancer remains a highly lethal disease, often diagnosed at advanced stages and with a very poor prognosis. Therefore, new strategies for the prevention and treatment of lung cancer are urgently needed. The aim of the present study was to determine the anti-tumorigenic effects of docosahexaenoic acid monoacylglyceride (MAG-DHA), a newly patented DHA derivative in lung adenocarcinoma. Our results demonstrate that MAG-DHA treatments decreased cell proliferation and induced apoptosis in A549 human lung carcinoma cells whereas MAG-DHA treatment did not induce apoptosis of normal bronchial epithelial BEAS-2B cells. MAG-DHA decreased NFκB activation leading to a reduction in COX-2 expression level in both A549 cells and lung adenocarcinoma tissues. Furthermore, MAG-DHA treatment increased PTEN expression and activation concomitant with a decrease in AKT phosphorylation levels and enhanced apoptosis. Oral administration of MAG-DHA significantly reduced tumor growth in a mouse A549 xenograft model. Lastly, MAG-DHA markedly decreased COX-2 and enhanced PTEN protein expression in tumor tissue sections. Altogether, these data provide new evidence regarding the mode of action of MAG-DHA and strongly suggest that this compound could be of clinical interest in cancer treatment.

SigB is a dominant regulator of virulence in Staphylococcus aureus small-colony variants

Staphylococcus aureus small-colony variants (SCVs) are persistent pathogenic bacteria characterized by slow growth and, for many of these strains, an increased ability to form biofilms and to persist within host cells. The virulence-associated gene expression profile of SCVs clearly differs from that of prototypical strains and is often influenced by SigB rather than by the agr system. One objective of this work was to confirm the role of SigB in the control of the expression of virulence factors involved in biofilm formation and intracellular persistence of SCVs. This study shows that extracellular proteins are involved in the formation of biofilm by three SCV strains, which, additionally, have a low biofilm-dispersing activity. It was determined that SigB activity modulates biofilm formation by strain SCV CF07-S and is dominant over that of the agr system without being solely responsible for the repression of proteolytic activity. On the other hand, the expression of fnbA and the control of nuclease activity contributed to the SigB-dependent formation of biofilm of this SCV strain. SigB was also required for the replication of CF07-S within epithelial cells and may be involved in the colonization of lungs by SCVs in a mouse infection model. This study methodically investigated SigB activity and associated mechanisms in the various aspects of SCV pathogenesis. Results confirm that SigB activity importantly influences the production of virulence factors, biofilm formation and intracellular persistence for some clinical SCV strains.

Cigarette smoke-induced proteostasis imbalance in obstructive lung diseases

The airway and alveolar surface is exposed daily to 8,000 L of air containing oxygen, particles, bacteria, allergens and pollutants, all of which have the potential to induce oxidative stress within cells. If one is also a cigarette smoker, then the exposure to reactive oxidants increases exponentially. More than any other tissue, the lung is at risk of undergoing oxidative changes in protein expression, structure and function. The oxidant burden of chronic cigarette smoke exposure can overwhelm the lung cells' capacity to maintain proteostasis, a process of regulated protein synthesis, folding and turnover. Somewhat surprisingly, most chronic cigarette smokers do not develop chronic obstructive pulmonary disease (COPD), likely because cells initiate a highly effective unfolded protein response (UPR) in the presence of oxidant-derived endoplasmic reticulum (ER) stress that allows cells to survive. The UPR initiates several signaling pathways that decrease protein translation, limit cell cycle progression, increase protein degradation and chaperone-mediated protein folding, and activate the transcription factor Nrf2 that induces antioxidant gene expression. Each of these actions decreases ER stress in a process of "healthy proteostasis". If these responses are insufficient, apoptosis ensues. In this article, we review the mechanisms of healthy and dysfunctional proteostasis related to cigarette smoke exposure and COPD.

Plasma biomarkers and cystic fibrosis lung disease

Purpose: The purpose of this study was to determine whether plasma biomarkers reflect changes in lung function and respiratory exacerbations associated with CF lung disease. Methods: Plasma human leukocyte elastase/alpha1 antitrypsin complex (pHLE complex) values were measured in 28 adult CF patients and 47 healthy volunteers and correlated with forced expiratory volume (FEV1) and forced vital capacity (FVC). pHLE complexes were studied during respiratory exacerbations and after antibiotic therapy. Plasma cytokines and sialic acid were also measured. Results: pHLE complexes were increased in CF patients (p < 0.01), were inversely correlated with FEV1 (r = 0.71) and FVC (r = 0.67) and returned to normal levels after intravenous antibiotics (p < 0.001). Plasma cytokines did not correlate with lung function. Total sialic acid increased during CF respiratory exacerbations and decreased after antibiotic therapy. Conclusion: Plasma sialic acid and pHLE complexes reflect clinically meaningful changes in CF lung disease. In contrast, plasma cytokine levels did not correlate with lung function

The prostanoid 15-deoxy-Δ12,14-prostaglandin-j2 reduces lung inflammation and protects mice against lethal influenza infection

BACKGROUND

Growing evidence indicates that influenza pathogenicity relates to altered immune responses and hypercytokinemia. Therefore, dampening the excessive inflammatory response induced after infection might reduce influenza morbidity and mortality.

METHODS

Considering this, we investigated the effect of the anti-inflammatory molecule 15-deoxy-Δ(12,14)-prostaglandin J(2) (15d-PGJ(2)) in a mouse model of lethal influenza infection.

RESULTS

Administration of 15d-PGJ(2) on day 1 after infection, but not on day 0, protected 79% of mice against lethal influenza infection. In addition, this treatment considerably reduced the morbidity associated with severe influenza infection. Our results also showed that treatment with 15d-PGJ(2) decreased influenza-induced lung inflammation, as shown by the diminished gene expression of several proinflammatory cytokines and chemokines. Unexpectedly, 15d-PGJ(2) also markedly reduced the viral load in the lungs of infected mice. This could be attributed to maintained type I interferon gene expression levels after treatment. Interestingly, pretreatment of mice with a peroxisome proliferator-activated receptor gamma (PPARγ) antagonist before 15d-PGJ(2) administration completely abrogated its protective effect against influenza infection.

CONCLUSIONS

Our results demonstrate for the first time that treatment of mice with 15d-PGJ(2) reduces influenza morbidity and mortality through activation of the PPARγ pathway. PPARγ agonists could thus represent a potential therapeutic avenue for influenza infections.

Lysosomotropic drugs inhibit maturation of transforming growth factor-beta

Transforming growth factor-beta (TGFbeta) is synthesized as a precursor protein, pro-TGFbeta, that must be cleaved by a furin-like proteinase before it becomes biologically active. We hypothesized that alkalinization of the trans-Golgi network (TGN)/endosome system may suppress pro-TGFbeta processing and decrease TGFbeta secretion. This hypothesis was tested in human A549 alveolar epithelial and T98G glioblastoma cell lines and in C57BL/6 mice. Inhibition of furin-like activity with decanoyl-RVKR chloromethylketone suppressed pro-TGFbeta processing, thereby significantly reducing the levels of secreted TGFbeta. Brefeldin A, bafilomycin A1, ammonium chloride, and monensin also prevented pro-TGFbeta processing. The alkalinizing lysosomotropic drugs chloroquine, hydroxychloroquine, amodiaquine, and azithromycin had a similar effect on the overall production of mature bioactive TGFbeta. Reduced levels of secreted TGFbeta were also associated with a decrease in Smad2 signaling. Mice treated with chloroquine showed a decrease in bronchoalveolar lavage fluid TGFbeta. We conclude that alkalinizing lysosomotropic drugs inhibit pro-TGFbeta processing.

High-dose ibuprofen in cystic fibrosis: Canadian safety and effectiveness trial

OBJECTIVE

To assess the effectiveness and safety of high-dose ibuprofen when used as part of routine therapy in patients with cystic fibrosis (CF).

STUDY DESIGN

In this multicenter, double-blinded, placebo-controlled trial, a total of 142 patients age 6 to 18 years with mild lung disease (forced expiratory volume in 1 minute [FEV1] > 60 predicted) were randomized to receive either high-dose ibuprofen (70 subjects, 20 to 30 mg/kg/twice daily, adjusted to a peak serum concentration of 50 to 100 mug/mL) or placebo (72 subjects) for a 2-year period. The primary outcome was the annualized rate of change in FEV1% predicted.

RESULTS

The patients in the high-dose ibuprofen group exhibited a significant reduction in the rate of decline of forced vital capacity percent predicted (0.07 +/- 0.51 vs -1.62 +/- 0.52; P = .03), but not FEV1%. The ibuprofen group also spent fewer days in hospital after adjusting for age (1.8 vs 4.1 days per year; P = .07). A total of 11 patients (4 in the ibuprofen group and 7 in the placebo group) withdrew due to adverse events.

CONCLUSIONS

High-dose ibuprofen has a significant effect on slowing the progression of lung disease in CF and generally is well tolerated.

Antioxidants in cystic fibrosis. Conclusions from the CF antioxidant workshop, Bethesda, Maryland, November 11-12, 2003

Although great strides are being made in the care of individuals with cystic fibrosis (CF), this condition remains the most common fatal hereditary disease in North America. Numerous links exist between progression of CF lung disease and oxidative stress. The defect in CF is the loss of function of the transmembrane conductance regulator (CFTR) protein; recent evidence that CFTR expression and function are modulated by oxidative stress suggests that the loss may result in a poor adaptive response to oxidants. Pancreatic insufficiency in CF also increases susceptibility to deficiencies in lipophilic antioxidants. Finally the airway infection and inflammatory processes in the CF lung are potential sources of oxidants that can affect normal airway physiology and contribute to the mechanisms causing characteristic changes associated with bronchiectasis and loss of lung function. These multiple abnormalities in the oxidant/antioxidant balance raise several possibilities for therapeutic interventions that must be carefully assessed.

Prolastin aerosol therapy and sputum taurine in cystic fibrosis

BACKGROUND

Neutrophil elastase in the cystic fibrosis airways inhibits opsonophagocytosis and induces the expression of interleukin-8, a neutrophil chemoattractant. Prolastin is a therapeutic preparation of alpha-1 proteinase inhibitor (alpha1,-PI), a neutrophil elastase inhibitor. The objective of this study was to determine the effects of Prolastin aerosol therapy on airway inflammation in cystic fibrosis.

METHODS

The primary endpoint of this study was sputum taurine, an amino-acid present in high concentrations in neutrophils. Sputum taurine correlates with respiratory exacerbations of cystic fibrosis. Seventeen patients with cystic fibrosis were each assigned to three sequential 10-day periods including first, aerosol therapy of 5 ml saline solution bid; second, aerosol therapy of 250 mg Prolastin bid; third, no aerosol therapy. On days 8, 9 and 10 of each period, early morning sputum was collected for the quantification of alpha1-PI, neutrophil elastase activity, IL-8 and taurine.

RESULTS

During Prolastin therapy, a 3-fold increase in sputum alpha1-PI was observed (P = 0.002). Baseline values of sputum alpha1-PI correlated with the values obtained after Prolastin aerosol (R = 0.77, P < 0.01). Sputum neutrophil elastase activity remained unchanged but taurine decreased after Prolastin therapy (during therapy P = 0.052, after therapy P = 0.026). Prolastin aerosol therapy had no adverse effect on pulmonary function.

CONCLUSIONS

Aerosol therapy with Prolastin in patients with cystic fibrosis leads to a progressive decrease in sputum taurine. This suggests that even in the absence of sustained elastase inhibition, Prolastin aerosol therapy may have a beneficial effect on airway inflammation in patients with cystic fibrosis.

Mechanical airway clearance using the frequencer electro-acoustical transducer in cystic fibrosis

PURPOSE

Clearance of mucus from airways is the cornerstone of therapy for lung disease in patients with cystic fibrosis (CF). This paper describes the operation of the Frequencer, a novel respiratory physiotherapy device comprised of an electro-acoustical transducer. We hypothesized that the Frequencer would be a safe and effective therapy to help clear secretions from the airways of subjects with CF.

METHODS

To verify this hypothesis, 22 individuals with CF were recruited to this study comparing sputum production during conventional chest physiotherapy (CCPT) and Frequencer therapy using a crossover design. The sputum weight was the main outcome measure.

RESULTS

Sputum weight was found to be a reproducible measure of the efficacy of chest physiotherapy in individual patients. The Frequencer induced airway clearance in patients with CF that was equivalent to that of CCPT. Furthermore, treatment of a 4% mucin preparation ex vivo with the Frequencer significantly reduced the viscosity of the mucin solution as determined in a capillary rheometer.

CONCLUSIONS

These results indicate the Frequencer is safe and as effective as CCPT in inducing airway clearance in patients with CF.

Cystic Fibrosis Transmembrane Conductance Regulator Function Is Suppressed in Cigarette Smokers

RATIONALE

Cigarette smoke extract inhibits chloride secretion in human bronchial epithelial cells. Oxidants decrease gene expression, protein expression, and function of the cystic fibrosis transmembrane conductance regulator (CFTR).

OBJECTIVES

Because cigarette smoke is a rich source of oxidants, we verified the hypothesis that CFTR may be suppressed by exposure to cigarette smoke in vitro and in vivo.

METHODS

The effects of cigarette smoke exposure on Calu-3 and T84 cell CFTR expression and function were observed. Also studied were the nasal potential differences (PDs) in 26 men (9 smokers, 17 nonsmokers) who had no detectable CFTR gene mutations as determined during investigations for infertility. CFTR expression and function were determined by Northern blotting, Western blotting, and cAMP-dependent 125I efflux assays. Extensive CFTR genotyping was performed in each subject. Nasal PD measurements were made at baseline and during amiloride, chloride-free buffer, and isoproterenol perfusions.

MAIN RESULTS

Cigarette smoke decreased CFTR expression and function in Calu-3 and T84 cell lines. Furthermore, the nasal PDs of cigarette smokers showed a pattern typical of CFTR deficiency with a blunted response to chloride-free buffer and isoproterenol compared with nonsmokers (-9.6 +/- 4.0 vs. -22.3 +/- 10.1 mV; p < 0.001).

CONCLUSIONS

We conclude that cigarette smoke decreases the expression of CFTR gene, protein, and function in vitro and that acquired CFTR deficiency occurs in the nasal respiratory epithelium of cigarette smokers. We suggest that acquired CFTR deficiency may contribute to the physiopathology of cigarette-induced diseases such as chronic bronchitis.

Oxidant stress suppresses CFTR expression

Epithelial mucous membranes are repeatedly exposed to oxidants and xenobiotics. CFTR plays a role in glutathione transepithelial flux and in defining the hydration and viscoelasticity of protective mucus. We therefore hypothesized that CFTR expression and function may be modulated by oxidant stress. A sublethal oxidant stress (tert-butylhydroquinone, BHQ) in CFTR-expressing epithelial cells (T84) induced a significant increase in cellular glutathione that was associated with an increase in expression of the gene encoding the heavy subunit of the rate-limiting enzyme for glutathione synthesis, gamma-glutamylcysteine synthetase (gamma-GCShs). CFTR gene expression was markedly decreased according to a time course that mirrored the changes in gamma-GCShs. Western blot analysis confirmed that the decrease in CFTR gene expression was associated with a decrease in CFTR protein. cAMP-dependent iodide efflux was also decreased by the oxidant stress. Nuclear run-on assays indicated that the oxidant stress had no effect on CFTR gene transcription, but the mRNA stability in the oxidant-stressed cells was markedly reduced. Furthermore, BHQ increased gamma-GCShs mRNA while decreasing CFTR mRNA in Calu-3 cells, and taurine chloramine induced similar effects in T84 cells. We conclude that suppression of CFTR expression may represent an adaptive response of mucosal epithelium to an exogenous oxidant stress.

Inhibition of gelatinase B (matrix metalloproteinase-9) by dihydrolipoic acid

Alpha-lipoic acid (LA) is a disulphide-containing fatty acid that is absorbed from the diet and transported to tissues. Once it has been taken up by mammalian cells, LA is reduced to dihydrolipoic acid (DHLA), a vicinal dithiol, and rapidly effluxed into the extracellular milieu. We hypothesized that DHLA may be an effective inhibitor of human gelatinase B (GelB). Purified human GelB was incubated with 0 to 200 µmol/L DHLA, and residual enzyme activity was measured by HPLC using a fluorogenic substrate (matrix metalloproteinase substrate III). DHLA inhibited GelB in a dose-dependent fashion with an IC50of 20 µmol/L. Oxidation of DHLA resulted in a loss of DHLA's capacity to inhibit GelB. The DHLA-mediated inhibition of GelB was independent of the zinc concentration in the reaction buffer. DHLA had no inhibitory effect on gelatinase A. Zymographs of activated neutrophil lysates demonstrated that higher concentrations of DHLA also prevent the activation of GelB proenzyme. Bronchoalveolar lavage fluid from mice fed a diet enriched with LA showed significantly increased GelB inhibitory capacity (p = 0.0002 vs. regular diet). We conclude that DHLA can modulate neutrophil-derived GelB activity through direct inhibition of enzyme activity and by preventing the activation of GelB proenzyme.Key words: matrix metalloproteinases, pulmonary fibrosis, thiols, neutrophils, inflammation.

Potential for antioxidant therapy of cystic fibrosis

PURPOSE OF REVIEW

Changes in redox state clearly play a role in airway inflammation and mucus rheology. Furthermore CFTR (cystic fibrosis transmembrane conductance regulator), the defective protein in cystic fibrosis (CF), not only is regulated by redox state but also directly modulates the epithelial redox environment through transepithelial flux of glutathione. The purpose of this review is to explore the potential therapeutic interest of antioxidant molecules in CF.

RECENT FINDINGS

Several antioxidants have been shown to have mucolytic and anti-inflammatory properties. Some antioxidants such as zinc and vitamin C may also help increase epithelial chloride secretion through CFTR-dependent and independent pathways. Other antioxidants are showing promise in helping CFTR mobilization to plasma membranes.

SUMMARY

The many levels of potential application offered by antioxidants make this class of molecules one of the promising areas of therapeutic development for CF. Several redox-modulating agents have a high likelihood of providing useful approaches for the treatment of many aspects of CF airway disease.

Ascorbate modulation of H2O2 and camptothecin-induced cell death in Jurkat cells

The effect of ascorbate on cell death was examined in Jurkat cells (human T-cell leukemia) by incubation with dehydroascorbate (DHA), which is rapidly taken up by cells and efficiently reduced to ascorbate. Apoptosis was evaluated by caspase-3 activity in cell extracts and flow cytometry of annexin V-labeled cells. In parallel, necrosis was estimated by the release of lactate dehydrogenase. Minor effects on cell death were observed when Jurkat cells were incubated with either DHA alone (100-1,000 microM) or a single dose of 10 microM H(2)O(2). However, pre-incubation with DHA followed by exposure to H(2)O(2) clearly stimulated both apoptosis and necrosis. In complete contrast, pre-incubation of cells with DHA significantly inhibited apoptosis, but did not affect necrosis, induced by the topoisomerase I inhibitor camptothecin. Our results indicate that intracellular ascorbate can modulate cell death in a manner which depends upon the nature of the apoptotic stimulus, which in turn has critical implications regarding the mechanism and potential application of ascorbate in cancer therapy.

Airway inflammation and infection in congenital bilateral absence of the vas deferens

In cystic fibrosis (CF), airway disease begins early in life. Bacteria and elevated levels of neutrophils and inflammatory mediators have been detected in bronchoalveolar lavage (BAL) fluid from infants with CF. Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) are common in men with congenital bilateral absence of the vas deferens (CBAVD) and it has been suggested that this syndrome represents a mild form of CF. We hypothesized that men with CBAVD also have subclinical pulmonary disease. Bronchoscopy with BAL, viral and quantitative bacterial cultures, and analyses of total and differential cell count, cytokines, and free neutrophil elastase was performed in eight men with CBAVD, who had mutations in the CFTR and intermediate or elevated sweat chloride levels, and in four healthy control subjects. There was light growth of Staphylococcus aureus in one of eight men with CBAVD, and small numbers of opportunistic gram-negative bacteria in six of eight men with CBAVD and in one control subject. BAL cell counts and neutrophil elastase were within the normal range. Interleukin-8 and tumor necrosis factor-alpha levels were higher for men with CBAVD than for control subjects. These data suggest that mutations in the CFTR in men with CBAVD, in addition to causing infertility, lead to subclinical bacterial pulmonary infection and inflammation consistent with mild CF.

Activation of matrix metalloproteinase-2 and -9 by 2- and 4-hydroxyestradiol

Breast cancer patients frequently develop metastases. This process requires the degradation of extracellular matrix proteins which act as a barrier to tumour cell passage. These proteins can be degraded by proteases, mainly the matrix metalloproteinases (MMPs). MMP-2 and -9 which are frequently detected in breast cancer tissues. ProMMPs are released from cancer cells, and their activation is considered to be a crucial step in metastases development. In breast cancer, estrogen metabolism is altered favouring the accumulation of 2- and 4-hydroxyestradiol (2- and 4-OHE(2)). These estradiol metabolites can generate free radicals. Since reactive species are known activators of proMMPs, this study was designed to determine if the free radicals generated by 2- and 4-OHE(2) can activate proMMP-2 and -9. Activation of MMPs by hydroxyestradiol was determined by monitoring the cleavage of a fluorogenic peptide and by zymography analysis. Both estradiol metabolites activated the MMP-2 and -9. 4-OHE(2) was a more potent activator than 2-OHE(2), which reflects its higher capacity to generate free radicals. ProMMPs activation was mainly mediated through O(2)*-, although the free radical HO* also activated the proMMPs but to a lesser extent. ProMMPs activation was not observed with estrogens that cannot generate free radicals, i.e. estradiol, estrone, 2- and 4-methoxyestradiol, and 16alpha-hydroxyestrone. These results demonstrate that 2- and 4-OHE(2) at a concentration as low as 10(-8)M can activate the proMMP-2 and -9 and might play an important role in the invasion of breast cancer cells.

Zinc chelators inhibit eotaxin, RANTES, and MCP-1 production in stimulated human airway epithelium and fibroblasts

Asthma is characterized by an increased production of eosinophil-active C-C chemokines by the airway epithelium. Recent studies have identified the presence of important quantities of labile zinc in the conducting airways. We hypothesized that modulation of this labile zinc could influence the production of proinflammatory chemokines in respiratory epithelial cells. The zinc chelator N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) and the heavy metal chelator 2,3-dimercapto-1-propanesulfonic acid (DMPS) were used to reduce the labile zinc content of A549, BEAS-2B, and HFL-1 cells. Northern blot analysis and RNase protection assay were used to study the effects of the zinc chelators on mRNA expression. DMPS and TPEN specifically inhibited the production of eotaxin, regulated on activation, normal T-cell expressed, and presumably secreted, and monocyte chemotactic protein-1 in TNF-alpha-stimulated respiratory epithelial cells and fibroblasts through labile zinc chelation. The inhibitory effects of DMPS and TPEN were associated with the decreased binding of the zinc-finger transcription factor GATA-1, whereas no change in NF-kappaB activation was observed. Together these results demonstrate that modulation of the labile pool of zinc can regulate gene expression and protein synthesis of C-C chemokines in lung epithelial cells and fibroblasts.

Vitamin C augments lymphocyte glutathione in subjects with ascorbate deficiency

BACKGROUND

Ascorbate and glutathione play central roles in the defense against free radicals and oxidants that are implicated in chronic diseases.

OBJECTIVE

The objective was to determine the ability of vitamin C supplements to modulate the concentration of glutathione in human lymphocytes.

DESIGN

The effect of vitamin C supplements was determined in a sequential study with time points before supplementation, after 13 wk of vitamin C supplements (500 or 1000 mg/d), and after 13 wk of matching placebo. The supplementation group was selected on the basis of low plasma ascorbate (<33 mmol/L) and consisted of 48 healthy men and women, smokers and nonsmokers, aged 25-64 y. Ascorbate and glutathione were measured in purified lymphocytes.

RESULTS

At baseline, the mean (+/-SD) concentration of plasma ascorbate was 19.5 +/- 7.2 micro mol/L, 22.5 micro mol/L below the median of normal distribution. The ascorbate concentration in plasma was linearly associated with that in lymphocytes (r = 0.53, P < 0.001). On supplementation with vitamin C, lymphocyte ascorbate increased by 51% (from 16.7 +/- 4.9 to 25.3 +/- 6.9 nmol/mg protein; P < 0.001) and was accompanied by an increase of lymphocyte glutathione by 18% (from 22.5 +/- 4.5 to 26.6 +/- 6.5 nmol/mg protein; P < 0.001). After placebo, the ascorbate and glutathione concentrations fell to near baseline concentrations (17.1 +/- 5.4 and 23.5 +/- 6.4 nmol/mg protein, respectively). No significant interaction was observed for sex and smoking status. Finally, the changes in lymphocyte ascorbate after supplementation were strongly associated with changes in lymphocyte glutathione (r = 0.71, P < 0.001). The association suggests that every 1-mol change in ascorbate is accompanied by a change of approximately 0.5 mol in glutathione.

CONCLUSION

Vitamin C supplements increase glutathione in human lymphocytes.

Polyethylene glycol conjugation at Cys232 prolongs the half-life of alpha1 proteinase inhibitor

alpha1 Proteinase inhibitor (alpha1PI), a natural inhibitor of the serine proteinase leukocyte elastase, is also an intravenous therapeutic agent used to treat hereditary emphysema and may be useful in other respiratory disorders. However, to achieve sustained suppression of leukocyte elastase, alpha1PI must be given frequently and in large amounts, thus limiting its clinical use. We hypothesized that conjugating alpha1PI with polyethylene glycol (PEG) at Cys(232) could extend the in vivo half-life of alpha1PI in blood and lung. We present evidence that site-specific conjugation with either 20 or 40 kD PEG at Cys(232) of nonglycosylated recombinant human alpha1PI (rhalpha1PI) results in an active inhibitor with prolonged in vivo stability. In addition, 72 h after airway instillation PEG-rhalpha1PI was found to be significantly better than glycosylated alpha1PI in protecting the lung against leukocyte elastase-mediated lung hemorrhage. We conclude that thiol-specific PEGylation markedly improves the in vivo pharmacokinetic profile of rhalpha1PI and represents a simple, novel strategy to address the therapeutic goal of human leukocyte elastase inhibition.

Leukocyte elastase inhibition therapy in cystic fibrosis: role of glycosylation on the distribution of alpha-1-proteinase inhibitor in blood versus lung

Cystic fibrosis patients demonstrate an increased susceptibility to bacterial lung infections. Airway infiltration by neutrophils will then lead to an increase in human leukocyte elastase (HLE) within the extracellular compartment, thereby producing deleterious effects. Here, we investigated the properties and tissue distribution of an unglycosylated, recombinant form of the HLE inhibitor alpha-1-proteinase inhibitor (alpha(1)-antitrypsin rhalpha1PI) when it is administered to the airway surface. We produced rhalpha1PI using a bacterial expression system and found the purified protein to be indistinguishable from blood-purified, glycosylated alpha1PI at inhibiting elastase in vitro. In contrast to intravenous administration, direct delivery of either alpha1PI or rhalpha1PI to the airway surface of CD-1 mice by nasal instillation produced similar highly detectable levels of protein in bronchoalveolar lavage at all time points, suggesting that glycosylation of alpha1PI does not play the same critical role in determining protein stability at the respiratory surface as it does in the vascular compartment. Interestingly, this unglycosylated rhalpha1PI was also highly protective against elastase-mediated injury 24 h after rhalpha1PI instillation and was consistently found to be significantly more protective than glycosylated blood-derived alpha1PI. Thus, these results provide evidence that aerosol delivery of rhalpha1PI could be an effective strategy for controlling HLE-dependent pathophysiology associated with cystic fibrosis lung disease.

In vitro generation of peroxynitrite by 2- and 4-hydroxyestrogens in the presence of nitric oxide

Estrogen metabolism is altered in most, if not all, breast cancer tumors. These alterations primarily lead to the formation of the catechol estrogen metabolites, 2- and 4-hydroxyestrogens, which can generate superoxide anion radicals (O(2)(*)(-)) through the redox cycling of semiquinone/quinone derivatives. In breast cancer cells, the activity of nitric oxide synthase is also frequently elevated, resulting in an increased level of exposure to nitric oxide ((*)NO). Since (*)NO rapidly reacts with O(2)(*)(-) to produce the peroxynitrite anion (ONOO(-)), this study was undertaken to determine whether ONOO(-) can be generated when 2- and 4-hydroxyestrogens are incubated in vitro with (*)NO donor compounds. Using dihydrorhodamine 123 as a specific probe for ONOO(-) formation, a ratio of 100 microM dipropylenetriamine NONOate (DPTA/NO) to 10 microM 4-hydroxyestradiol (4-OHE(2)) gave an optimal ONOO(-) production of 11.9 +/- 1.9 microM (mean +/- SD). Quantification of ONOO(-) was not modified by mannitol, supporting the idea that the hydroxyl radical was not involved. This production of ONOO(-) required the presence of the catechol structure of estrogen metabolites since all methoxyestrogens that were tested were inactive. Hydroxyestrogen metabolites derived from estradiol showed the same efficiency in producing ONOO(-) as those originating from estrone. With DPTA/NO, the 4-hydroxyestrogens generated 30-40% more ONOO(-) than the 2-hydroxyestrogens. Optimal production of ONOO(-) was assessed with DPTA/NO and diethylenetriamine NONOate (initial (*)NO generation rates of 0.76 and 0.08 microM min(-1), respectively). With faster (*)NO-releasing compounds, such as diethylamine NONOate and spermine NONOate, lower levels of ONOO(-) were detected. These data suggest that once the optimal concentration of (*)NO was obtained, the reaction between (*)NO and 4-OHE(2) was saturated. The excess of (*)NO would probably react with aqueous oxygen to form nitrite (NO(2)(-)). Since the third-order reaction rate for the reaction between 2(*)NO and O(2) is 2 x 10(6) M(-2) s(-1), it can therefore be suggested that the reaction between (*)NO and 4-OHE(2) occurs at a faster rate.

Synthesis and evaluation of novel β-lactam inhibitors of human leukocyte elastase

A series of β-lactam derivatives were synthesized and tested to determine the structure-activity relationship for inhibition of human leukocyte elastase (HLE), a serine protease involved in several degenerative lung and tissue diseases. The most potent IC50 values were obtained with neutral hydrophobic 7α-methoxy cephalosporanic acid derivatives. Tryptophanyl-9-fluorenylmethyl ester and N-benzhydryl piperazine derivatives of 7α-methoxy cephalosporanic acid represent two novel HLE inhibitors, with length of action persisting beyond 24 h.Key words: β-lactams, neutrophil elastase, protease inhibitors, peptides.