Differential elemental distribution of retained particles along the respiratory tract

Abstract

Context: Prolonged exposure to ambient particles is associated with premature mortality due to cardio-respiratory diseases and lung cancer. The size and composition of these particles determine their toxicity, which is aggravated by their long-term retention in the lungs.

Objective: To compare the elemental profile of particles retained along the bronchial tree and lymph nodes by combining laser capture microdissection (LCM) and elemental composition analysis through energy dispersive x-ray (EDX) and scanning electron microscopy (SEM).

Material and methods: Twenty-four right lung middle lobes from autopsied cases were obtained from two cities with different pollution backgrounds. Lung samples were collected from three distinct sites within the lung at the time of autopsy: peribronchial tissue, peripheral parenchyma and hilar lymph nodes. Areas of potentially increased particle deposition were microdissected using LCM and analyzed for elemental composition through EDX “allied” with SEM.

Results: Elemental analyses of the particles retained along the bronchial tree showed two groups of distribution: peribronchiolar or lymph node deposition. The elemental profile of peribronchial areas were significantly different between the two cities and were better discriminators of past air pollution exposure.

Conclusion: Our data suggest that particle uptake varies along the bronchial tree and human lung tissue retains particles indicative of regional air pollution background.

Keywords::

• microdissection
• lung
• air pollution
• microscopy
• electron
• scanning
• spectrometry
• x-ray emission

Acknowledgments

The authors would like to thank Prof. Francis Green for his estimated help and contribution to the present study.

Declaration of interest

I hereby declare that this manuscript has not been published elsewhere and it has not been submitted simultaneously for publication elsewhere. All authors have contributed to the manuscript, and aware of its submission.

Prof. Paulo H N Saldiva, Prof. Thais Mauad and Prof. Patricia Cury are funded by “Fundação de Amparo a Pesquisa do Estado de São Paulo” (FAPESP) and “Conselho Nacional de Desenvolvimento Científico e Tecnológico” (CNPq). There are no other potential conflicts of interest.