Possible mechanism of chrysotile asbestos-stimulated superoxide anion production in guinea pig alveolar macrophages

Excessive production of active oxygen radicals by macrophages is proposed to play an important role in asbestos-related diseases. The purpose of this study was to examine the capacity and mechanisms of action of various forms of asbestos to stimulate superoxide anion production by guinea pig alveolar macrophages. Chrysotile, but not the amphiboles (crocidolite, anthophyllite, or amosite), stimulated a rapid (<1 min) and dose-dependent (2.5-50 μg/ml) production of superoxide anion at noncytotoxic doses (2.5 to 25 μg/ml). The stimulation of superoxide anion production by chrysotile could be blocked by putative protein kinase C inhibitors (staurosporine, sphingosine, and fluphenazine). Chrysotile also stimulated phosphatidylinositol turnover as measured using ³²P_i incorporation into phospholipids, [³H]-diacylglycerol levels, and intracellular calcium mobilization as measured using fura-2 and ⁴⁵Ca. In addition, pertussis toxin partially blocked chrysotile-stimulated superoxide anion production. We conclude that the mechanism of guinea pig alveolar macrophage stimulation by chrysotile, but not the amphibole asbestos forms, is consistent with a mechanism which is similar to that used by agonists such as N-formyl-Nle-Leu-Phe resulting in stimulated phosphatidylinositol turnover, calcium mobilization, and activation of protein kinase C.