RESUMEN
BACKGROUND: Several diseases have been related to asbestos exposure, including the pleural tumor mesothelioma. The mechanism of pleural injury by asbestos fibers is not yet fully understood. The inflammatory response with release of mediators leading to a dysregulation of apoptosis may play a pivotal role in the pathophysiology of asbestos-induced pleural disease. OBJECTIVE: To determine whether pro-inflammatory cytokines produced by asbestos-exposed pleural mesothelial cells modify the injury induced by the asbestos. METHODS: Mouse pleural mesothelial cells (PMC) were exposed to crocidolite or chrysotile asbestos fibers (3.0 µg/cm(2)) for 4, 24, or 48 h and assessed for viability, necrosis and apoptosis, and the production of cytokines IL-1ß, IL-6 and macrophage inflammatory protein-2 (MIP-2). Cells exposed to fibers were also treated with antibodies anti-IL-1ß, anti-IL-6, anti- IL-1ß+anti-IL-6 or anti-MIP-2 or their irrelevant isotypes, and assessed for apoptosis and necrosis. Non-exposed cells and cells treated with wollastonite, an inert particle, were used as controls. RESULTS: Mesothelial cells exposed to either crocidolite or chrysotile underwent both apoptosis and necrosis and released cytokines IL-1ß, IL-6 and MIP-2. In the crocidolite group, apoptosis and the levels of all cytokines were higher than in the chrysotile group, at comparable concentrations. Neutralization of IL-1ß andIL-6, but not MIP-2, inhibited apoptosis and necrosis, especially in the cells exposed to crocidolite fibers. CONCLUSIONS: Both crocidolite and chrysotile asbestos fibers induced apoptosis and produced an acute inflammatory response characterized by elevated levels of IL-1ß, IL-6 and MIP-2 in cultured mouse PMC. IL-1ß and IL-6, but not MIP-2, were shown to contribute to asbestos-induced injury, especially in the crocidolite group.
Asunto(s)
Asbesto Crocidolita/toxicidad , Asbestos Serpentinas/toxicidad , Citocinas/metabolismo , Células Epiteliales/metabolismo , Células Epiteliales/patología , Animales , Apoptosis/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Quimiocina CXCL2/antagonistas & inhibidores , Quimiocina CXCL2/metabolismo , Citocinas/antagonistas & inhibidores , Células Epiteliales/efectos de los fármacos , Interleucina-1beta/antagonistas & inhibidores , Interleucina-1beta/metabolismo , Interleucina-6/antagonistas & inhibidores , Interleucina-6/metabolismo , Ratones , Necrosis/inducido químicamente , Pleura/citologíaRESUMEN
BACKGROUND: South Africa's export of each of its three types of asbestos, crocidolite, amosite, and chrysotile, and the total amounts to 84 countries in metric tonnes is examined over a 24-year period, 1980-2003. METHODS: For convenience, the countries are divided into nine world regional groups, Europe, Eastern Europe, North America with the Caribbean, South America, Africa, Middle East, Far East, South Asia, and Oceania. RESULTS: The three greatest importing countries of total asbestos in metric tonnes were all in the Far East region, ranging from Japan, South Korea to Thailand, and followed by USA and Italy. All exports to all countries diminished steadily as the South African trade came virtually to an end by 2003, due to ever increasing international pressure. CONCLUSION: The export trade has changed significantly since 1960 from being dominantly to European countries to being directed in recent years to the Far East, with serious implications for asbestos-related ill-health in those countries.