Enzymatic activities of bronchoalveolar lavages in coal workers pneumoconiosis

Pulmonary cystic keratinizing squamous cell lesions of rats after inhalation/instillation of different particles

Cystic keratinizing squamous cell lesions from three inhalation studies (Study A, B, C) and one intratracheal instillation study (Study D) in rats were reclassified and a certain number of lesions examined immunohistochemically for PCNA (proliferating cell nuclear antigen) as a marker of cellular proliferation. The following classification was used: squamous cell metaplasia with marked keratinization, keratinizing cyst, cystic keratinizing epithelioma, cystic keratinizing squamous cell carcinoma, keratinizing squamous cell carcinoma and non-keratinizing squamous cell carcinoma. In study A (inhalation of coal oven exhaust and subcutaneous injection of a high dose of DB (ah)A) 49.3% of rats developed cystic keratinizing squamous cell carcinomas. Inhalation of coal oven exhaust gas together with intratracheal instillation of crocidolite or subcutaneous injection of a low dose DB(ah)A (dibenz(ah)anthracene) resulted in cystic keratinizing squamous cell carcinomas in 23% to 24% of the rats. High incidences of cystic squamous cell carcinomas in the range of 31.9% to 76.4% were observed in rats of Study B1 after a 10-months exposure to tar/pitch condensation aerosol (different B(a)P (benzo(a)pyrene) concentrations) with added carbon black in some groups. After a 20-months exposure period to the same inhalation atmospheres (Study B2) the incidence of squamous cell carcinomas was increased up to 95.8%. Exposure of rats to various concentrations of unfiltered diesel exhaust (Study C) resulted in incidences of cystic keratinizing epitheliomas ranging from 2.5% (2.5 mg/m3) to 10.7% (7.5 mg/m3). Epitheliomas were also observed in 16.2% of carbon black and 16.0% of titanium dioxide exposed rats. Only a few cystic keratinizing squamous cell carcinomas occurred. In the intratrachel instillation study (Study D) increased incidences of cystic keratinizing epitheliomas occurred in rats exposed to native diesel exhaust particles (16.7%), high dose of extracted diesel exhaust particles (14.6%), extracted printex 90-carbon black particles (18.8%), and extracted printex 90-carbon black particles + B(a)P (18.8%). High indicences of cystic keratinizing squamous cell carcinomas were noted in rats that received 15 mg B(a)P (14.6%) or 30 mg B(a)P (72.7%) intratracheally. Immunohistochemical labeling of nuclei with PCNA demonstrated proliferative activity in one or two (and focally more than two) peripheral cell layers of cystic keratinizing epitheliomas and in more than three peripheral cell layers of cystic keratinizing squamous cell carcinomas and keratinizing squamous cell carcinomas. The wall of keratinizing cysts showed no or a weak reaction.

N-acetyl-beta-D-glucosaminidase activity within BAL from macaques exposed to generic coal dusts

N-acetyl-beta(beta)-D-glucosaminidase is a lysosomal enzyme secreted by alveolar macrophages in response to phagocytosis of particulate material. Alveolar macrophages participate in the degradation and fibrosis of pulmonary tissue that results in pneumoconiosis. Known quantities of four characterized respirable dusts were bronchoscopically placed into the right caudal lung lobe of macaque monkeys. Bronchoalveolar lavage (BAL) samples were collected from dust-exposed right lung and unexposed left lung of the same individuals at 2-week intervals for 12 weeks after dust instillation. The samples were tested for N-acetyl-beta-D-glucosaminidase activity to determine if the enzyme levels could serve as an indicator of pulmonary injury induced by generic coal dusts when compared to known fibrogenic and nuisance dusts. Installation of generic quartz, anthracite, or TiO2 dusts produced significant elevations of enzyme activity and increased numbers of macrophages in the dust-exposed lobes. Elevations in enzymatic activity and macrophage numbers were greatest in response to generic quartz dust. These results suggest that quantitative levels of N-acetyl-beta-D-glucosaminidase activity may be a useful indicator of acute and chronic lung injury following exposure to fibrogenic and nonfibrogenic dusts.

Arylneuraminidase activity of Pseudomonas aeruginosa does not degrade natural substrates such as human respiratory mucins

The culture supernatant from a single Pseudomonas aeruginosa strain has been reported to show neuraminidase activity, leading to the speculation that this bacterium may use this enzyme as a virulence factor to act on host macromolecules. In order to extend this finding, we have examined the activity of concentrated P. aeruginosa culture supernatants and cells on synthetic and natural substrates containing sialic acid, such as human respiratory mucins. Four P. aeruginosa strains showed some activity on the synthetic substrate 4-methylumbelliferyl-alpha-D-N-acetylneuraminic acid but failed to liberate N-acetylneuraminic acid from six different natural substrates. Attempts to induce enzyme production by use of human respiratory mucins in the culture medium were also unsuccessful. The supernatants also showed N-acetyl-beta-D-glucosaminidase-like activity on a synthetic substrate but did not liberate N-acetylhexosamines from natural substrates. We conclude that the neuraminidase-like activity observed in P. aeruginosa can be defined as an arylneuraminidase and that the possession of a neuraminidase active on natural substrates is not a common attribute of P. aeruginosa strains.

Persistent biological reactivity of quartz in the lung: raised protease burden compared with a non-pathogenic mineral dust and microbial particles

This study assessed the potential harmfulness of particles in the lung by measuring their ability to elicit and maintain an inflammatory response and to damage lung tissue. It compared the inflammogenicity of two nondurable, biological particulates (Corynebacterium parvum and zymosan) with a pathogenic mineral dust (quartz) and a nonpathogenic dust (titanium dioxide) by dosing rats via the intratracheal route and measuring the consequent alveolitis. The magnitude and duration of the inflammatory response were assessed by measuring the total number of leucocytes and the percentage of neutrophils obtained by bronchoalveolar lavage. Two key functional parameters of the lavaged leucocytes--ability to degrade fibronectin and production of plasminogen activator--were also measured. A marked inflammatory response had occurred by one day after instillation, characterised by increases in total leucocyte numbers and percentage of neutrophils in the bronchoalveolar lavages, with all four test materials. In all but the quartz exposed animals, the inflammation subsided rapidly thereafter, approaching control levels by 15 days after injection; in the quartz exposed animals the alveolitis persisted for up to 30 days. All of the inflammogens generated chemotaxins in rat serum in vitro and so, by analogy, might also be expected to generate chemotactic activity in alveolar lining fluid which could contribute to the generation of an inflammatory response. The cellular inflammatory response was accompanied by a concomitant increase in the proteolytic activity of the bronchoalveolar lavage leucocytes but production of plasminogen activator remained unchanged. In vitro exposure to the inflammogens had no effect on the proteolytic activity against fibronectin or on the plasminogen activator activity of bronchoalveolar leucocytes.

Inflammatory responses in lungs of rats inhaling coalmine dust: enhanced proteolysis of fibronectin by bronchoalveolar leukocytes

Chronic exposure to coalmine dust is associated with the accumulation of inflammatory leukocytes in the bronchoalveolar region of the lung and, in the long term, with fibrosis and emphysema of the lung parenchyma. Degradation of connective tissue by inflammatory leukocytes has been implicated in the parenchymal damage that precedes the development of fibrotic or emphysematous lesions in the lung. The ability of inflammatory leukocytes obtained by bronchoalveolar lavage from rats inhaling coalmine dust to degrade fibronectin in vitro was assessed. The animals were exposed to an airborne mass concentration of dust similar to the maximum permissible level in United Kingdom collieries. The bronchoalveolar lavage cell population showed changes with duration of dust exposure; there were increases in the total number of leukocytes and in the percentage of polymorphonuclear leukocytes, and the macrophage component of the lavage became increasingly activated, as assessed by the ability of these cells to spread on glass. In addition, degradation of a radiolabelled fibronectin matrix by the coalmine dust exposed bronchoalveolar leukocytes increased with duration of dust exposure. Thus exposure to airborne coalmine dust causes an influx of inflammatory leukocytes to the alveolar region. These cells have enhanced ability to degrade fibronectin and this may be important in subsequent disease development.

Biochemical and cellular changes in bronchoalveolar lavaged samples from rats after inhalation of mosquito-coil smoke

A group of 30 female albino rats were exposed to mosquito-coil smoke, 8 hours a day, 6 days per week, for 6 months. Another group which was exposed to air served as control. At the end of the experiment, the enzyme activities, total protein and lecithin contents as well as cellular responses in the lung lavage between the control and smoke-exposed rats were compared. Morphological observations using scanning and transmission electron microscopy demonstrated that the alveolar macrophages of smoke-exposed rats lost their typical ruffled membranes. They possessed small cytoplasmic processes on their smooth cell surfaces, small particles in phagolysosomes and mitochondria with a very electron-dense matrix. The levels of total protein and lecithin and the activities of lactate dehydrogenase, acid phosphatase and beta-glucuronidase in the lung-lavage fluid of smoke-exposed rats were significantly (P less than 0.05) higher than those of the controls. Increases (P less than 0.05) of serum enzymes, including lactate dehydrogenase, aspartate aminotransferase, isocitrate dehydrogenase and aldolase, indicated damage of liver tissues, but the levels of serum urea and urea nitrogen remained at the control levels implying normal functions of the kidneys of the mosquito-coil smoke-exposed rats. The level of serum tri-iodothyronine also increased significantly (P less than 0.05), but thyroxine remained at the control level.

Identification of plasma proteins contained in bronchoalveolar fluid from Macacus cynomolgus

1. Serial bronchoalveolar lavages (BAL) were performed on a subhuman primate (Macacus cynomolgus) in order to give an experimental model for silicosis. 2. We have identified and quantified some plasma proteins of monkey BAL fluid. 3. The results were compared to those previously obtained in humans. 4. Two proteins previously detected in human BAL fluid (alpha 1 acid glycoprotein, alpha 1 antichymotrypsin) were not detected in monkey control BAL fluid. 5. Two kinds of transferrins were detected in monkey BAL fluids while only one is described in human. 6. The present results will now permit sequential follow up studies during the course of experimental silicosis.

Characterization of the lower respiratory tract inflammation of nonsmoking individuals with interstitial lung disease associated with chronic inhalation of inorganic dusts

The pneumoconioses, interstitial lung disorders resulting from the inhalation of inorganic dusts, are associated with chronic inflammatory processes in the lower respiratory tract. To characterize these inflammatory processes in relation to the pathogenesis of these disorders, we studied 39 nonsmoking individuals with long-term occupational exposures to inorganic dust and functional evidence of interstitial disease (asbestosis, n = 18; coal workers' pneumoconiosis, n = 15; silicosis, n = 6). In all 3 disorders, the inflammation was dominated by alveolar macrophages. Because a common feature of these interstitial lung diseases is concurrent injury and fibrosis of alveolar walls, we assessed whether these alveolar macrophages were spontaneously releasing mediators capable of giving rise to these changes. Alveolar macrophages from the study population were spontaneously releasing increased amounts of superoxide anion and hydrogen peroxide (both p less than 0.01 compared to normals), oxidants capable of injuring lung parenchymal cells. The alveolar macrophages were also spontaneously releasing significantly increased amounts of fibronectin and alveolar macrophage-derived growth factor (both p less than 0.01 compared to normals), mediators that act synergistically to signal fibroblast replication. Taken together, these findings define a major role for the alveolar macrophage in mediating the alveolar wall injury and fibrosis that characterize the common pneumoconioses and suggest that the alveolar macrophage is an important "target" for developing strategies designed to prevent loss of lung function in these individuals.

Pulmonary emphysema: current concepts of pathogenesis

Pulmonary emphysema is a major public health problem and is primarily a disease of smokers. The pathogenesis of emphysema in smokers is likely to be multifactorial and may involve protease-antiprotease imbalance, abnormal host response to injury, the inactivation of antiproteases by oxidants, and direct damage of lung tissue by pulmonary phagocytes. The data regarding current concepts of pathogenesis of emphysema in smokers are reviewed in this article.

Comparison of hydrolases, peroxidase and protease inhibitors in bronchoalveolar fluid from Macacus cynomolgus and human controls

1. Serial bronchoalveolar lavages were performed on a subhuman primate (Macacus cynomolgus) in order to give an experimental model for silicosis. 2. We have measured glycosidases, proteases, peroxidase and antiproteases of the BAL fluids from seven normal monkeys. 3. The results obtained were similar to those found in human control BAL fluids. 4. For monkeys, the repetition of the bronchoalveolar procedure does not seem to have an important influence on the values obtained. 5. The present results will now permit sequential follow up studies during the course of experimental silicosis.