asbestos--amosite and Pleural-Effusion

Pleural inflammation is a sequela of exposure to toxic mineral fibers such as amosite asbestos. This inflammatory response involves the influx of leukocytes from the vasculature into the pleural space. Adhesion molecules such as intercellular adhesion molecule-1 (ICAM)-1 and chemokines such as monocyte chemoattractant protein-1 (MCP)-1 and macrophage inhibitory protein-2 (MIP)-2 are known to be important in pulmonary inflammation following inhalation of particulate matter. However, little is known about their role in pleural inflammation secondary to amosite asbestos exposure. Because the pleural mesothelial cell is believed to be a key target cell of asbestos exposure, the purpose of this study was to determine if ICAM-1, MCP-1, and MIP-2 proteins were secreted by these mesothelial cells following in vitro and in vivo exposure to amosite asbestos. Increased levels of ICAM-1 and MCP-1 protein were measured following 24 or 48 hours exposure of cultured rat pleural mesothelial cells to amosite fibers (1.5 to 5.0 micro g/cm(2)). Increased levels of ICAM-1, MCP-1, and MIP-2 protein were found in pleural lavage fluid from Fischer-344 rats exposed to amosite asbestos for 4 and 12 weeks and after a 12-week recovery period (following the 12-week exposure period). These findings suggest that the secretion of ICAM-1, MCP-1, and MIP-2 by rat pleural mesothelial cells may contribute to amosite-induced pleural inflammation.

Topics: Administration, Inhalation; Animals; Asbestos, Amosite; Asbestos, Crocidolite; Chemokine CCL2; Chemokine CXCL2; Chemokines, CXC; Culture Media, Conditioned; Dose-Response Relationship, Drug; Epithelium; Intercellular Adhesion Molecule-1; Intercellular Signaling Peptides and Proteins; Male; Monokines; Pleura; Pleural Effusion; Pleurisy; Rats; Rats, Inbred F344; Specific Pathogen-Free Organisms

The ability of amosite asbestos fibers to induce chromosomal aberrations in human primary mesothelial cells obtained from pleural effusions of 10 noncancerous patients was investigated. The glutathione S-transferase M1 (GSTM1) genotypes of the patients were determined, since the GSTM1 null genotype has been associated with increased susceptibility to lung cancer and chemically induced cytogenetic damage. Four of the patients represented the GSTM1 null genotype, and six the GSTM1 positive genotype. Successful chromosome aberration analyses were obtained from six cases, three of them with the GSTM1 null genotype. The level of aberrant cells in unexposed cultures ranged from 2.0% to 7.5%. Statistically significant increases (2.3-3.0-fold compared to controls) in the number of aberrant cells were observed in two cases only: in one case treated with 1 microgram/cm2 of amosite, and in another treated with 2 micrograms/cm2 of amosite. Cell cultures from four individuals showed minor or no increases in the numbers of aberrant cells in the doses tested (1 and 2 micrograms/cm2). Chromosome breaks were the major type of aberration. The amosite exposed cells with significantly increased aberrations were from patients with GSTM1 positive genotypes. Two cases that showed no cytogenetic response to asbestos fibers were of the GSTM1 null genotype. Thus, our results suggest that the lack of the GSTM1 gene does not render human mesothelial cells more susceptible to chromosomal damage induced by asbestos. GSTM1 null cells appeared, however, to be more sensitive to the growth inhibitory effects of asbestos than did GSTM1 positive cells. Variation in the cytogenetic response of human primary mesothelial cells to asbestos fibers was observed to exist, but the fibers do not appear to be potent inducers of structural chromosomal aberrations in these cells. It remains to be established whether individual sensitivity to asbestos fibers, due to specific genetic traits, exists.

Topics: Adult; Aged; Aged, 80 and over; Asbestos, Amosite; Cell Division; Cells, Cultured; Chromosome Aberrations; Epithelium; Female; Genetic Predisposition to Disease; Genotype; Glutathione Transferase; Humans; Male; Middle Aged; Mitotic Index; Pleural Effusion; Polymorphism, Genetic