Fig. 5

Aggravated lung fibrosis was related to increased accumulated MARCO⁺CCL6⁺ AMs in aged mice. Bleomyclin (BLM, 2.5 mg/kg, i.n.) was used to induce lung fibrosis in mice. Lung samples were harvested 21 days post-BLM treatment. A Histopathology of lung tissue was performed by Masson Trichrome staining. Ashcroft scores were used to indicate the degree of fibrosis. Data are shown as the mean ± SEM. Comparisons by unpaired two-tailed Student’s t-test. ** p < 0.01. B The hydroxyproline in lung tissue was detected by using hydroxyproline microplate assay kit. C The mRNA expression levels of Col1a1, Timp1 and α-SMA in lung tissue were detected by using real-time PCR. D Co-staining of MARCO and CCL6 in the aged lung tissues detected by immunofluorescence, compared with those in the young. The arrows indicate the positive cells in the lung tissues. Scale bar, 25 μm. E MARCO⁺ CCL6⁺ cell numbers were counted and analyzed. Each symbol represents the average of 10 fields of vision (63 ×) from an individual sample. F The levels of UGRP1 in the lung tissues and BALF (1.0 mL/mouse) were detected by ELISA. There were 6 mice in each group. Data are shown as the mean ± SEM. Comparisons by two-way analysis of variance (ANOVA) followed by Tukey’s test or by unpaired two-tailed Student’s t-test. ns, not significant, *** p < 0.001, **** p < 0.0001