Department of Public Health Sciences

Distribution of Ambient Particulate Matter and Tissue Remodeling in the Human Lung

Pinkerton, K.E., F.Y. Green, Vallyathan V., C.G. Plopper, V. Gopal, D. Hung, E.B. Bahne, M.G. Menache, M.B. Orenstein and M.B. Schenker

Submitted for publication. 1999. .

We examined the relationship between carbonaceous/mineral dust exposure, intrapulmonary particle distribution, and remodeling of the airways along anatomically distinct airway paths in the lungs of Hispanic males from the Central Valley of California. In this ongoing study, lung autopsy specimens from the Fresno County Coroner's Office were prepared by intratracheal instillation of 2% glutaraldehyde at 30cm H20 pressure. Two distinct airway paths into the apico-posterior and apico-anterior portions of the left upper lung lobe were followed. Tissue samples for histological analysis were generally taken from the second, fourth, sixth and ninth airway generations. Parenchymal tissues beyond the twelfth airway generation of each airway path were also analyzed. Microscopic evaluation demonstrated normal airway structure to the sixth airway generation. There was little evidence of mineral dust accumulation except in lymphoid tissues. In contrast, terminal and respiratory bronchioles arising from each pathway revealed varying degrees of wall thickening and remodeling. Walls with marked thickening contained moderate to heavy amounts of carbonaceous and mineral dusts. Wall thickening was associated with increases in collagen and interstitial inflammatory cells, including dust-laden macrophages. These changes were significantly (p < 0.001) greater in the first generation respiratory bronchiole (RB) compared to second and third generation RBs. These findings suggest that accumulation of carbonaceous and mineral dust in the lungs is significantly affected by lung anatomy with the greatest retention in centers of lung acini. Furthermore, we demonstrate significant remodeling of this transitional zone in humans exposed to ambient particulate matter.

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