Dynamic change of circulating monocyte subsets in the mouse model of quartz-induced pneumosilicosis and its implication / 医学研究生学报

ABSTRACT

Objective Pneumosilicosis is characterized by pulmonary fibrosis and cannot be effectively treated at present. This study was to explore the changes of monocyte subsets in the mouse model of silicon dioxide-induced experimental pneumosilicosis and the correlation of the changes with lung inflammatory injury and pulmonary fibrosis. Methods A total of 100 male C57BL/6J mice weighing 18-22 g were equally randomized into a normal saline (NS) group and a silicon dioxide (quartz) group.The model of experimental pneumosilicosis was established by oropharyngeal aspiration of quartz suspension.At 1, 3, 7, 14, and 28 days after treat-ment, the mice were sacrificed and the proportions of different circulating monocyte subpopulations determined by flow cytometry.Dif-ferent types of inflammatory cells in the bronchoalveolar lavage fluid ( BALF) were routinely counted.The inflammation score and col-lagen volume fraction ( CVF) of the lung tissue were obtained by HE and picrosirius red staining. Results At 7 days after quartz treatment, silicotic nodules were observed in the lung tissue.Compared with the NS controls, the model mice showed significantly in-creased inflammation score and CVF at 7 days (0.920 ±0.049 vs 1.400 ±0.089, P0.05).Compared with the NS controls, the quartz-treated mice showed markedly increased proportion of Ly6Chimonocytes at all time points, which peaked at 7 days (58.750 ±2.386 vs 78.300 ±2.517, P<0.01), with a positive corre-lation with the inflammation score (P<0.01) and CVF of the lung tissue (P<0.01) at 7 and 28 day. Conclusion The propor-tions of circulating Ly6Chi and Ly6Clo monocytes changed dynamically in the murine model of quartz-induced experimental pneumosilico-sis.The increased proportion of the Ly6Chi monocyte subpopulation might be closely related with lung inflammatory injury and pulmona-ry fibrosis in pneumosilicosis.