Objective To study autophagy activity changes and apoptosis of alveolar macrophages (AMs) in lung lavage fluid retrieved from patients at various stages of silicosis.
Methods Observed participants with exposure to silicious dust and silicosis patients at stage I, II, and III (n=30 for each group) were chosen as study subjects. Information of occupational history was collected, and AMs of all subjects were harvested by massive whole lung lavage. The morphologies of autophagosome precursor, autophagosome, and autolysosome were observed under transmission electron microscope. Early apoptosis of AMs was also detected.
Results Autophagosomes were found around the nuclear in the AMs of the observed participants. Autophagosome precursors were identified in the AMs of the stage I silicosis patients, but other cytoplasm organelles were rarely seen. Autophagosomes and autolysosomes in the stage II silicosis patients were also found. Primary lysosomes of different sizes were observed in the stage III silicosis patients, but no typical autophagosome precursor, autophagosome, or autolysosome. The AMs apoptosis rates in the observed participants and the stage I, II & III silicosis patients were (15.28& #177;0.20)%, (18.13& #177;0.58)%, (19.56& #177;1.07)%, and (23.92& #177;2.52)% respectively, and the differences among them were statistically significant (P < 0.01).
Conclusion There are differences in the autophagic activity and apoptosis of AMs among silicosis patients at different stages. AMs autophagy and apoptosis may play an important role in the development of silicosis.
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