The significance of nanoparticles in particle-induced pulmonary fibrosis

Abstract

Exposure to airborne nanoparticles contributes to many chronic pulmonary diseases. Nanoparticles, classified as anthropogenic and natural particles, and fibers of diameters less than 100 nm, have unrestricted access to most areas of the lung due to their size. Size relates to the deposition efficiency of the particle, with particles in the nano-range having the highest efficiencies. The deposition of nanoparticles in the lung can lead to chronic inflammation, epithelial injury, and further to pulmonary fibrosis. Cases of particle-induced pulmonary fibrosis, namely pneumoconiosis, are mostly occupationally influenced, and continue to be documented around the world. The tremendous growth of nanotechnology, however, has spurred fears of increased rates of pulmonary diseases, especially fibrosis. The severity of toxicological consequences warrants further examination of the effects of nanoparticles in humans, possible treatments and increased regulatory measures.

Keywords: Nanoparticles; asbestosis; fibrosis; nanotubes; pneumoconiosis; silicosis.

Figure 1

Silicosis in a 56-year-old male who worked in stonecutting for 25 years. (A) Chest radiograph shows multiple variable-sized nodular lesions in both lungs, predominantly in the upper and middle zones. (B) Axial thin-section CT scan (1.0-mm-thick section) obtained at the level of the azygos arch shows multiple small nodules with a perilymphatic (centrilobular plus subpleural) distribution in the upper lobe of both lungs. Note the tendency toward coalescence of the nodules in the lung periphery (arrows). With copyright permission from RSNA and Dr. Kyung Soo Lee (29).

Figure 2

Case 1, LM: (A) Dense fibrotic area of the lung with many aluminum-containing macrophages. (Original magnification × 10.) (B) Lung parenchyma showing peribronchiolar and interstitial aluminum-containing macrophages. (Original magnification × 10.). (C) Aluminumcontaining macrophages in lymph node. (Original magnification × 180.) (42). With copyright permission from Elsevier and Dr. Jerrold Abraham.