Trypsin-Like Proteases and Their Role in Muco-Obstructive Lung Diseases.

Trypsin-like proteases (TLPs) belong to a family of serine enzymes with primary substrate specificities for the basic residues, lysine and arginine, in the P1 position. Whilst initially perceived as soluble enzymes that are extracellularly secreted, a number of novel TLPs that are anchored in the cell membrane have since been discovered. Muco-obstructive lung diseases (MucOLDs) are characterised by the accumulation of hyper-concentrated mucus in the small airways, leading to persistent inflammation, infection and dysregulated protease activity. Although neutrophilic serine proteases, particularly neutrophil elastase, have been implicated in the propagation of inflammation and local tissue destruction, it is likely that the serine TLPs also contribute to various disease-relevant processes given the roles that a number of these enzymes play in the activation of both the epithelial sodium channel (ENaC) and protease-activated receptor 2 (PAR2). More recently, significant attention has focused on the activation of viruses such as SARS-CoV-2 by host TLPs. The purpose of this review was to highlight key TLPs linked to the activation of ENaC and PAR2 and their association with airway dehydration and inflammatory signalling pathways, respectively. The role of TLPs in viral infectivity will also be discussed in the context of the inhibition of TLP activities and the potential of these proteases as therapeutic targets.

Guanylyl cyclase activation reverses resistive breathing-induced lung injury and inflammation.

Inspiratory resistive breathing (RB), encountered in obstructive lung diseases, induces lung injury. The soluble guanylyl cyclase (sGC)/cyclic guanosine monophosphate (cGMP) pathway is down-regulated in chronic and acute animal models of RB, such as asthma, chronic obstructive pulmonary disease, and in endotoxin-induced acute lung injury. Our objectives were to: (1) characterize the effects of increased concurrent inspiratory and expiratory resistance in mice via tracheal banding; and (2) investigate the contribution of the sGC/cGMP pathway in RB-induced lung injury. Anesthetized C57BL/6 mice underwent RB achieved by restricting tracheal surface area to 50% (tracheal banding). RB for 24 hours resulted in increased bronchoalveolar lavage fluid cellularity and protein content, marked leukocyte infiltration in the lungs, and perturbed respiratory mechanics (increased tissue resistance and elasticity, shifted static pressure-volume curve right and downwards, decreased static compliance), consistent with the presence of acute lung injury. RB down-regulated sGC expression in the lung. All manifestations of lung injury caused by RB were exacerbated by the administration of the sGC inhibitor, 1H-[1,2,4]oxodiazolo[4,3-]quinoxalin-l-one, or when RB was performed using sGCα1 knockout mice. Conversely, restoration of sGC signaling by prior administration of the sGC activator BAY 58-2667 (Bayer, Leverkusen, Germany) prevented RB-induced lung injury. Strikingly, direct pharmacological activation of sGC with BAY 58-2667 24 hours after RB reversed, within 6 hours, the established lung injury. These findings raise the possibility that pharmacological targeting of the sGC-cGMP axis could be used to ameliorate lung dysfunction in obstructive lung diseases.

Kinase inhibitors in the treatment of obstructive pulmonary diseases.

Chronic pulmonary diseases, including chronic obstructive pulmonary disease (COPD) and asthma, are major causes of death and reduced quality of life. Characteristic of chronic pulmonary disease is excessive lung inflammation that occurs in response to exposure to inhaled irritants, chemicals, and allergens. Chronic inflammation leads to remodeling of the airways that includes excess mucus secretion, proliferation of smooth muscle cells, increased deposition of extracellular matrix proteins and fibrosis. Protein kinases have been implicated in mediating inflammatory signals and airway remodeling associated with reduced lung function in chronic pulmonary disease. This review will highlight the role of protein kinases in the lung during chronic inflammation and examine opportunities to use protein kinase inhibitors for the treatment of chronic pulmonary diseases.

Leukotriene C4 synthase and ischemic cardiovascular disease and obstructive pulmonary disease in 13,000 individuals.

Ischemic cardiovascular disease and obstructive pulmonary disease involve inflammation. Leukotrienes may be important pro-inflammatory mediators. We tested the hypothesis that the (-1072)G > A and (-444)A > C promoter polymorphisms of leukotriene C4 synthase confer risk of transient ischemic attack (TIA), ischemic stroke, ischemic heart disease (IHD), asthma, and chronic obstructive pulmonary disease (COPD). We genotyped individuals from the Danish general population, the Copenhagen City Heart Study, and Danish patients with IHD/coronary atherosclerosis, the Copenhagen Ischemic Heart Disease Study. We used prospective (n = 10,386), cross-sectional (n = 10,386), and case-control (n = 2392 + 5012) designs. Allele frequency was 0.07 for (-1072)A and 0.29 for (-444)C. Cumulative incidence for TIA was higher for (-1072)AA versus GG genotype (log-rank: p < 0.001), and lower for (-444)CC versus AA genotype (log-rank: p = 0.03). Cumulative incidence for ischemic stroke was also lower for (-444)CC versus AA genotype (log-rank: p = 0.04). Multifactorially adjusted hazard ratios for TIA were 5.2(95% CI:1.9-14) for (-1072)AA versus GG genotype, and 0.4(0.2-1.0) for (-444)CC versus AA genotype. Corresponding values were 1.9 (0.7-5.2) and 0.7 (0.5-1.0) for ischemic stroke, and 0.8 (0.4-1.6) and 1.0 (0.9-1.2) for IHD. In the case-control study, corresponding multifactorially adjusted odds ratios for IHD/coronary atherosclerosis were 0.5 (0.2-1.3) and 1.2 (1.0-1.5). These genotypes were not associated with risk of asthma or COPD. Leukotriene C4 synthase promoter genotypes influence risk of TIA and ischemic stroke, but not risk of IHD/coronary atherosclerosis, asthma, or COPD.

Enzyme replacement therapy stabilizes obstructive pulmonary Fabry disease associated with respiratory globotriaosylceramide storage.

Fabry disease is an X-linked glycosphingolipidosis caused by a deficiency of α-galactosidase A, a lysosomal enzyme. Symptoms in hemizygous males and heterozygous females are due to lysosomal storage of globotriaosylceramide in the central and peripheral nervous system, vascular endothelium, cardiac valves and myocytes, gastrointestinal tract, and renal epithelium. Pulmonary involvement is also a recognized manifestation of Fabry disease, but histopathological evidence of pulmonary lysosomal storage is scant. We report a 51-year-old woman with a G43R α-galactosidase A mutation and normal spirometry testing 2.5 years prior to presentation, who experienced a dry, nonproductive cough that persisted despite treatment with antibiotics and bronchodilators. Spirometry demonstrated a mixed restrictive/obstructive pattern as well as impaired gas exchange. Patchy ground-glass pulmonary interstitial infiltrates were found on plain radiography and computerized tomography. She underwent an open lung biopsy that demonstrated peribronchiolar fibrosis and smooth-muscle hyperplasia. Prominent inclusion bodies of the bronchiolar/arteriolar smooth muscle and endothelium were present. Electron microscopy indicated the inclusion bodies were lamellated zebra bodies consistent with globotriaosylceramide storage. Enzyme replacement therapy (ERT) with agalsidase-beta was instituted. Since initiation of therapy, she occasionally has a dry cough but markers of obstructive lung disease have remained stable in the past 4 years. This report demonstrates that pulmonary involvement in Fabry disease is due to lysosomal storage, and suggests that ERT is capable of stabilizing pulmonary Fabry disease. However, progressive worsening of her total lung capacity indicates that ERT cannot reverse the ongoing process of fibrosis also seen in Fabry disease.

Inducible targeting of IL-13 to the adult lung causes matrix metalloproteinase- and cathepsin-dependent emphysema.

Cigarette smoke exposure is the major cause of chronic obstructive pulmonary disease (COPD). However, only a minority of smokers develop significant COPD, and patients with asthma or asthma-like airway hyperresponsiveness or eosinophilia experience accelerated loss of lung function after cigarette smoke exposure. Pulmonary inflammation is a characteristic feature of lungs from patients with COPD. Surprisingly, the mediators of this inflammation and their contributions to the pathogenesis and varied natural history of COPD are not well defined. Here we show that IL-13, a critical cytokine in asthma, causes emphysema with enhanced lung volumes and compliance, mucus metaplasia, and inflammation, when inducibly overexpressed in the adult murine lung. MMP-2, -9, -12, -13, and -14 and cathepsins B, S, L, H, and K were induced by IL-13 in this setting. In addition, treatment with MMP or cysteine proteinase antagonists significantly decreased the emphysema and inflammation, but not the mucus in these animals. These studies demonstrate that IL-13 is a potent stimulator of MMP and cathepsin-based proteolytic pathways in the lung. They also demonstrate that IL-13 causes emphysema via a MMP- and cathepsin-dependent mechanism(s) and highlight common mechanisms that may underlie COPD and asthma.

Long time enzyme replacement therapy stabilizes obstructive lung disease and alters peripheral immune cell subsets in Fabry patients.

BACKGROUND: Fabry disease is an X-linked lysosomal storage disorder, causing accumulation of globotriaosylceramid in different organs. Glycolipids are activators of different immune cell subsets the resulting inflammation is responsible for organ damage. Pulmonary involvement leads to airway inflammation; however, data on severity, as well as the effect of enzyme replacement therapy on lung function parameters and changes in peripheral immune cell subsets on lung involvement are sparse. METHODS: Seven Fabry patients and four carriers underwent detailed clinical examinations screening for pulmonary manifestations. Repetitive measurements were performed on five patients on ERT (average follow-up 5 years). Patients with Fabry disease and control volunteers were included into peripheral blood cell measurements. RESULTS: Lung involvement was present in all patients. Symptoms suggestive for lung disease were mild, however, obstructive ventilatory disorder, dominantly affecting small airways accompanied by hyperinflation was demonstrated in all affected patients. ERT resulted in small improvement of FEV1 in most treated patients. Decreased ratio of myeloid DC, Th17 cells while increase in T helper (Th)1 cells, and no change in Th2 and regulatory T (Treg) cells were detected in Fabry patients. CONCLUSIONS: Fabry disease results mainly in mild symptoms related to lung involvement, characterized by moderate non-reversible obstructive ventilatory disorder. Stabilization of airway obstruction during follow-up was observed using ERT in most patients, emphasizing the importance of this treatment in respect of pulmonary manifestations. Changes of immune cell subsets in the peripheral blood might play a role in inflammatory process, including small airways in Fabry patient's lung.

Myeloperoxidase concentration in bronchoalveolar lavage fluid from healthy horses and those with recurrent airway obstruction.

The aim of this work was to measure the myeloperoxidase (MPO) concentration in bronchoalveolar lavage (BAL) fluid collected from horses with recurrent airway obstruction (RAO), both in crisis and in remission, as well as from healthy horses. Seven horses with RAO were exposed to moldy hay until the maximum change in pleural pressure was greater than 1.5 kPa. At that point, BAL was performed, and the total cell counts and percentages in the fluid were immediately determined. To measure the MPO concentration in BAL-fluid supernatant, we used a specific enzyme-linked immunosorbent assay with polyclonal antibodies against equine MPO. The tests were repeated on the horses with RAO after they had spent 2 mo on pasture. Six healthy horses serving as controls underwent the same tests. The absolute and relative neutrophil counts and the MPO concentration in the BAL fluid were significantly greater in the horses with an RAO crisis than in the control horses. After 2 mo on pasture, the horses that had been in RAO crisis were clinically normal, and their neutrophil counts and MPO levels in BAL fluid had significantly decreased; during remission their neutrophil counts were not significantly different from those in the healthy horses, but their MPO concentration remained significantly higher. This study showed that determining the MPO concentration in a horse's BAL fluid is technically possible and that during remission from RAO the concentration remains higher than normal. Thus, MPO may be a marker of neutrophil presence and activation in the lower airways.

Localization of gamma-glutamylcysteine synthetase messenger rna expression in lungs of smokers and patients with chronic obstructive pulmonary disease.

Cigarette smoking results in an oxidant/antioxidant imbalance in the lungs and inflammation, which are considered to be key factors in the pathogenesis of chronic obstructive pulmonary disease (COPD). Glutathione (GSH) is an important protective antioxidant in lung epithelial cells and epithelial lining fluid. De novo GSH synthesis in cells occurs by a two-enzyme process. The rate-limiting enzyme is gamma-glutamylcysteine synthetase (gamma-GCS), in which the heavy subunit (HS) constitutes most of its catalytic activity. The localization and expression of gamma-GCS-HS in specific lung cells as well as possible differences in its expression between smokers with and without COPD have not yet been studied. The purpose of this study was to investigate gamma-GCS-HS expression using messenger RNA in situ hybridization in peripheral lung tissue. We studied 23 current or ex-smokers with similar smoking histories with (n = 11; forced expiratory volume in 1 s [FEV(1)] < 75% predicted) or without COPD (n = 12; FEV(1) < 84% predicted). We assessed the relations between pulmonary gamma-GCS-HS expression, FEV(1) and transforming growth factor-beta1 (TGFbeta(1)), because TGFbeta(1) can modulate gamma-GCS-HS expression in lung epithelial cells. Gamma-GCS-HS is predominantly expressed by airway and alveolar epithelial cells, alveolar CD68+ cells (macrophages), and endothelial cells of both arteries and veins. In subjects with COPD, semiquantitative analysis revealed higher levels of gamma-GCS-HS messenger RNA in alveolar epithelium (1.5 times, p <.04) and a trend for a higher expression in bronchiolar epithelium (1.3 times, p =.075) compared with subjects without COPD. We did not observe a significant correlation between airway and alveolar epithelial gamma-GCS-HS expression and TGFbeta(1) expression (r =.20), FEV(1) percentage predicted (r =.18), or FEV(1)/forced vital capacity ratio (r =.14; p.05). Our results show that gamma-GCS-HS is localized, particularly in lung epithelium, and shows higher expression in smokers with COPD. This suggests a specific role for enhanced GSH synthesis as a mechanism to provide an adaptive response against oxidative stress in patients with COPD.

Xanthine oxidase activity in bronchoalveolar lavage fluid from patients with chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a serious respiratory pathology characterized by irreversible limitation of expiratory flow and includes chronic obstructive bronchitis, chronic airflow limitation, and emphysema. To determine whether xanthine oxidase activity increased in the airspaces of COPD patients, we examined bronchoalveolar lavage fluid (BAL) from COPD patients recruited during a 2-year clinical study. Filtered BAL supernatant from COPD patients and healthy nonsmoking controls was examined by fluorometric analysis of DNA unwinding (FADU) and spectrophotometric assays (cytochrome c reduction kinetics and uric acid kinetics). Compared to controls, filtered BAL supernatant of subjects with COPD exhibited a detectable clastogenic activity probably related to superoxide production. The method of BAL preparation as an acellular system strongly suggests that superoxide production may be due to xanthine oxidase activity.

Alpha-1-proteinase inhibitor in inflammatory states of humans and laboratory animals.

Alpha-1-proteinase inhibitor (A1PI) was examined in various inflammatory conditions in terms of its capacity to inhibit leukocytic proteases and to act as a monitor of the presence of oxidants generated by stimulated leukocytes. Examination of bronchoalveolar lavage fluid from patients with pulmonary inflammatory disease indicated that oxidants are generated in situ in the inflammatory reaction of the lung; the oxidants could potentially injure tissue directly, and, by virtue of the inactivation of A1PI, prevent inhibition of the neutrophil elastase, potentially allowing unencumbered proteolytic attack of the neutrophil elastase on lung structures. Subsequent examination of leukocytic enzymes and oxidants in experimental pulmonary inflammation in animals also demonstrated the generation of oxidants during development of acute pulmonary inflammation and indicated that the neutrophil is the cell mainly responsible for the release of oxidants.

Role of connective tissue proteases in the pathogenesis of chronic inflammatory lung disease.

The normal structure and function of the human lung is dependent on the maintenance of the connective tissue matrix. These structural macromolecules provide the template for normal parenchymal cell architecture on which efficient gas exchange depends. In addition, the organization and amount of this extracellular matrix accounts for much of the mechanical behavior of the lung parenchyma during the respiratory cycle. The preservation of this intricate connective tissue scaffold depends on the lung's capacity to prevent enzymatic disruption of the component matrix proteins. Specifically, the integrity of the normal connective tissue skeleton of the lung is determined by the maintenance of a balance between proteases capable of cleaving these structural elements and the specific protease inhibitors. The normal extracellular matrix is preserved when the local concentrations of protease inhibitors prohibits expression of active connective tissue proteases within the lung parenchyma. Conversely, the disruption of lung structure during the course of acute and chronic inflammatory diseases of the lung is often associated with an imbalance of protease-antiprotease activity. The consequence is the expression of unimpeded proteolytic attack on the connective tissue matrix of the lung. In this context, the nature of the pulmonary lesion and its physiologic consequences, reflect the specificity of the expressed proteases for the individual connective tissue components. Experimental evidence suggests that the differential expression of collagenase and elastase, prototypes of connective tissue proteases, may determine whether the pathologic outcome is fibrosis (e.g., idiopathic pulmonary fibrosis) or destruction (e.g., emphysema) of the alveolar structures.

Proteases and antiproteases.

Serine proteases have been implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD) since the identification of alpha 1-antitrypsin deficiency in 1963. This inhibitor efficiently inactivates several enzymes released by activated neutrophils including neutrophil elastase, cathepsin G and proteinase 3, all of which have been shown to generate features of COPD in animal models. Recent studies have identified the mechanisms of enzyme release from activated neutrophils and indicate that the concentrations are usually two orders of magnitude above that of normal alpha 1-antitrypsin. This results in an area of obligate proteolysis in the immediate vicinity of a migrating neutrophil. The area is greatly enlarged in alpha 1-antitrypsin deficiency explaining the increased susceptibility of such patients to develop lung damage. The migration into and activation of neutrophils in the lung is likely to be a major determinant of the development of COPD. Understanding the processes has important implications for the design of new therapeutic strategies.

Matrix metalloproteinases and TIMPs: properties and implications for the treatment of chronic obstructive pulmonary disease.

The matrix metalloproteinases (MMPs) are a unique family of metalloenzymes that, once activated, can destroy connective tissue. The active enzymes are all inhibited by tissue inhibitors of metalloproteinases (TIMPs). The relative amounts of active MMPs and TIMPs are important in determining whether tissues are broken down in disease. Although elastase is often regarded as the target enzyme in chronic obstructive pulmonary disease (COPD), both the neutrophils and macrophages in the lung contain metalloproteinases and both collagen and elastin are degraded in disease. Transgenic studies have shown that when MMP1 is over-expressed, pulmonary emphysema develops in mice, while MMP12 knockout mice do not develop pulmonary emphysema when exposed to cigarette smoke. New drugs that can specifically block active MMPs are now available. These potent inhibitors are effective in vitro and prevent the destruction of tissue in animal models. Future patient trials will test the effectiveness of these compounds in preventing tissue destruction.

Alpha 1-antichymotrypsin mutations in patients with chronic obstructive pulmonary disease.

Mutations in the alpha 1-antichymotrypsin gene have been described which result in reduced levels of alpha 1-antichymotrypsin in the serum. Previous studies have suggested that two of these mutations (Pro227-->Ala and Leu55-->Pro) predispose to chronic obstructive pulmonary disease (COPD). We have investigated the prevalence of these mutations in 168 COPD patients and 61 controls without airflow obstruction. The prevalence of the Pro227-->Ala mutation was 0.9% and it was not associated with impaired lung function. None of the subjects had the Leu55-->Pro mutation.

Pulmonary function in Pi M and MZ grainworkers.

Twenty-eight men with the Pi MZ phenotype who have been employed in the Saskatchewan country grain elevators and thus regularly exposed to high levels of grain dust, were case matched for age, years of employment, employment status, smoking status, and smoking history with grainworkers of type Pi M. Individuals answered a questionnaire, had a chest roentgenogram, skin tests, and performed a battery of pulmonary function tests. There were no differences between the two groups in prevalence of symptoms or atopy. Although not statistically significant, the MZ group had three times as many individuals with abnormal roentgenograms suggestive of COPD as the M group. The Pi MZ grainworkers had consistently poorer mean results for the pulmonary function tests with significantly lower mean values for FEV1, FEV1/FVC, MMFR, and Vmax50, leading us to suggest that Pi MZ individuals may be at higher risk of COPD than Pi M individuals, but only in the presence of other risk factors such as grain dust exposure.

Serum angiotensin-converting enzyme activity, concentration, and specific activity in granulomatous interstitial lung disease, tuberculosis, and COPD.

Angiotensin-converting enzyme (ACE) activity in serum is used as an aid to the diagnosis and follow-up of patients with sarcoidosis. A theoretical limitation of measurements of activity is that these may be affected by the presence of pharmacologic or endogenous inhibitors of ACE. Immunoassays of ACE concentration avoid this problem and, when combined with tests of ACE activity, permit calculation of specific activity of ACE. In this study, we set out to develop a sensitive radioimmunoassay for ACE to compare results obtained with this method with results of ACE activity and calculated ACE specific activity in patients suffering from a variety of lung diseases. In a group of control subjects (n = 32), the ACE concentration was 453.7 +/- 159.8 (SD) ng/mL; 95% confidence interval (CI), 398.34 to 509.06, but levels were significantly elevated in sarcoidosis (979.3 +/- 558.6 ng/mL; 95% CI, 827.5 to 1,131.1; n = 51; p < 0.001 vs control subjects), silicosis (646.5 +/- 239.1 ng/mL; 95% CI, 544.2 to 748.8; n = 21; p < 0.01), and miliary tuberculosis (647.0 +/- 217.1 ng/mL; 95% CI, 551.9 to 742.1; n = 29; p < 0.01). The levels were normal in COPD, interstitial pulmonary fibrosis, and active cavitary pulmonary tuberculosis. The overall correlation between ACE activity and concentration measurements was strong (r = 0.93). No evidence of endogenous ACE inhibition was observed in any of the disease categories studied except in COPD where an elevation of ACE specific activity was observed, raising the possibility that in this condition different isozymes of ACE with higher specific activity might be released.

Human alveolar macrophage proteolytic enzyme activities in chronic obstructive pulmonary disease. Lack of correlation with functional abnormalities.

The occurrence of emphysema in people deficient in alpha1-antitrypsin and the production of emphysema in experimental animals with elastolytic enzymes suggest proteolysis as a mechanism for the development of emphysema. To investigate the possible role of pulmonary alveolar macrophages in the pathogenesis of emphysema, we measured elastase, acid protease, and elastase-like esterase activities in macrophages from patients with chronic obstructive lung disease and attempted to correlate the level of enzyme activity with the severity of pulmonary function abnormality measured in these patients. Compared to values for cigarette smokers with normal pulmonary function, these macrophage enzyme activities were not increased in patients with chronic obstructive lung disease, and there was no correlation of high elastase activity with more severe degrees of pulmonary function abnormality. These findings lead us to believe that the absolute level of proteolytic enzymes in pulmonary alveolar macrophages is not in itself a determinant of emphysema.

Elevation of plasma truncated elastase alpha 1-proteinase inhibitor complexes in patients with inflammatory lung diseases.

Human neutrophil elastase plays an important role in the development of several inflammatory lung diseases; however, there have been relatively few investigations using plasma samples. In this report, we describe alterations in the plasma elastase:alpha 1-PI complex in patients with chronic obstructive pulmonary disease (COPD) (15 cases), COPD with infection (8), diffuse panbronchiolitis (DPB) (8), bronchiectasis (9), pneumonia (10), and the adult respiratory distress syndrome (ARDS) (14), and in 15 normal volunteers. The elastase:alpha 1-PI complex concentration was determined by an enzyme-linked immunosorbent assay. Western immunoblot analysis of the elastase:alpha 1-PI complex was also performed. Plasma elastase:alpha 1-PI complex was also performed. Plasma elastase:alpha 1-PI complex levels in patients with COPD with infection (504 micrograms/L +/- 93 micrograms/L) were significantly higher, as compared with those with COPD but without infection (118 micrograms/L +/- 9 micrograms/L) and normal volunteers (122 micrograms/L +/- 4 micrograms/L). Increased complex concentrations were also found in patients with DPB and bronchiectasis (643 micrograms/L +/- 222 micrograms/L and 558 micrograms/L +/- 198 micrograms/L, respectively) as compared with normal volunteers. Increased complex concentrations were also found in patients with pneumonia and ARDS (450 micrograms/L +/- 101 micrograms/L and 1,400 micrograms/L +/- 438 micrograms/L, respectively). Western immunoblot analysis using anti-alpha 1-PI antibody and antineutrophil elastase antibody showed two types of elastase:alpha 1-PI complexes, one with a molecular weight of 60,000 daltons (60 kilodaltons [KD]) and the other at 50,000 daltons (50 KD). Although the native 80-KD elastase:alpha 1-PI complex was detected in bronchoalveolar lavage fluid, it was not found in plasma. In summary, these results demonstrated that levels of the truncated complex were increased in patients with various inflammatory lung diseases. This truncated form may play an important role in the pathophysiology of inflammatory processes.

Proteinase/proteinase inhibitor imbalance in sputum sol phases from patients with chronic obstructive pulmonary disease. Suggestions for a key role played by antileukoprotease.

In order to characterize the imbalance between proteinases and proteinase inhibitors in sputum sol phases, we studied 25 patients (mean age, 59 +/- 11 yr) with exacerbated chronic obstructive pulmonary disease (COPD). An aliquot of sputum was used for bacteriologic determinations, and the remainder was centrifuged in order to obtain gel and sol phases. On the basis of the bacteriologic data, patients were divided into colonized patients (14) and noncolonized patients (11). All of the major inhibitors were immunologically detectable in sol phases without a significant difference between colonized and noncolonized patients (alpha 1-proteinase inhibitor [alpha 1-PI], 2.56 microM +/- 0.53 microM and 2.39 microM +/- 0.72 microM; alpha 2-macroglobulin [alpha 2-MG], 0.21 microM +/- 0.07 microM and 0.16 microM +/- 0.05 microM; antileukoprotease (ALP), 1.78 microM +/- 0.57 microM and 1.53 microM +/- 0.6 microM, respectively [mean +/- SE]). With regard to proteinase activities, both free elastase-like and free chymotrypsin-like activities were detectable in the majority of patients (15/25) (0.59 microM +/- 0.15 microM and 0.74 microM +/- 0.15 microM for elastase-like activity [ELA], and 0.010 microM +/- 0.003 microM and 0.017 microM +/- 0.007 microM for chymotrypsin-like activity [CLA], respectively [mean +/- SE]). The inhibitory profile of proteinase activities, performed by means of a panel of inhibitors, allowed us to assign specific activities mainly to neutrophil elastase and cathepsin G (Cat G). Next we looked at the relationships between inhibitors and proteinase activities. We found a significant negative correlation between neutrophil elastase activity and ALP (r = -0.58; p < 0.01). In confirmation of this suggestion, sol phases were divided into samples (15) with detectable ELA (> 0.50 microM) and samples (10) with no detectable ELA (< 0.18 microM). Levels of alpha 1-PI and alpha 2-MG did not differ significantly between the two groups, whereas ALP values were higher in the group with no detectable ELA (3.12 microM +/- 0.69 microM) than in the other group (0.58 microM +/- 0.21 microM; p < 0.001). We conclude that most sputum sol phases from patients with exacerbated COPD have a high burden of free neutrophil elastase and Cat G. Antileukoprotease seems to be the major naturally occurring inhibitor effective in the modulation of proteinase activities in bronchial secretions under these conditions.