OBJECTIVETo evaluate the differences in the autophagy activity of alveolar macrophages between patients with different stages of coal workers' pneumoconiosis (CWP).

METHODSA total of 116 coal workers were investigated in the field. Their lung lavage fluid was collected and purified to obtain alveolar macrophages. The morphological characteristics of autophagy were observed by transmission electron microscopy. The expression of autophagy marker (LC3) and autophagy regulators (Beclin1, mTOR, and p-mTOR) was measured by Western blot. The autophagy activity of alveolar macrophages was compared between dust-exposed subjects and patients with stage I, II, and III CWP.

RESULTSThe autophagy activity of alveolar macrophages differed between patients with different stages of CWP, according to transmission electron microscopy. Patients with stage II CWP had significantly higher protein expression of LC3 II/I and Beclin1 in pulmonary macrophages than those with stage ICWP (P < 0.05); patients with stage III CWP had significantly lower protein expression of LC3 II/I and Beclin1 in pulmonary macrophages than those with stage II CWP (P < 0.05), but had significantly higher protein expression of LC3 II/I and Beclin1 than those with stage I CWP (P < 0.05); patients with stage II CWP had a significantly higher protein expression of Beclin1 than the dust-exposed subjects (P < 0.05). Patients with stage II CWP had significantly lower expression of mTOR and p-mTOR in pulmonary macrophages than the dust-exposed subjects and those with stage I CWP (P < 0.05), while patients with stage III CWP had significantly higher expression of mTOR and p-mTOR than those with stage II CWP (P < 0.05).

CONCLUSIONThe autophagy activity of alveolar macrophages varies between patients with different stages of CWP.