Biochemical and Cellular Mechanisms of Dust-Induced Lung Fibrosis

Biological reactivity of different crystalline forms of titanium dioxide in vitro and in vivo.

“…The elevation of the lyso somal enz yme acid ribonuclease in the free cell population of some samples may simply reflect a nonspecific response to dust phagocytosis. The data in table 2 provide a sha rp contrast between the effects of the titan ium dioxide samples and those of a toxic du st such as a-quartz, the results from the pulmonary surface being in agreement with similar studies showing excessive polymorphonuclear leucocyte infiltration of the lung (16) and pulmonary surfactant elevation, a condition that is progressive (10) .…”

Hypertrophy and Hyperplasia of Alveolar Type II Cells in Response to Silica and Other Pulmonary Toxicants

“…Do increased levels of surfactant serve to somehow protect the lungs, as suggested by the results of several studies (62,73)? The activation of Type II cells and the significance of the surfactant increases is an area which has received very little attention, but in view of the apparent generalized nature of the hypertrophic response, an important physiological function of the surfactant system may yet await discovery.…”

“…Asbestos and silica are well known as etiologic agents in the development of pulmonary fibrosis. It is, therefore, conceivable that the increases in surfactant induced by these fibrogenic dusts are somehow related to the progression of the fibrotic process (62). In this regard, it is noteworthy that nonfibrogenic dusts do not elicit a surfactant response (9,62).…”

“…For example, Gabor et al (9) found that extracellular surfactant levels remained elevated up to 26 weeks following exposure. Similarly, Richards and Curtis (62) found that the increases in extracellular surfactant produced by silica remained approximately five times higher than in control animals for as long as 48 weeks after exposure. Increases in surfactant following inhalation of chrysotile asbestos remained approximately 2.5-fold above control levels up to 50 weeks after exposure (57).…”

Pulmonary epithelial response in the rat lung to instilled Montserrat respirable dusts and their major mineral components

“…Pulmonary surfactant is a secretory product of alveolar type 2 cells and is significantly accumulated following exposure to bioreactive dusts such as quartz, 18 resulting from hypertrophic or hyperplastic changes in the lining cells. 19 GGT is a cell surface enzyme, present in alveolar epithelial type 2 and bronchiolar Clara cells, 13 involved in the recycling of reduced glutathione.…”