Fig. 3

Effect of adoptively transferring Tregs on bleomycin (BLM)-induced murine pulmonary fibrosis. a Outline of the experimental design used for the adoptive transfer of Tregs. Osmotic pumps containing 200 μL saline, with or without bleomycin (BLM; 100 mg/kg mouse body weight), were implanted subcutaneously through a small incision in the back according to the manufacturer’s instructions. BLM was infused continuously from day 0 to 6. Tregs (1 × 10⁶/mouse) were injected via the tail vein on day 14 after initiating BLM treatment. On day 28 post-BLM challenge, the mice were sacrificed and their lungs were removed and blood was collected for analyses. Each group included at least 6 mice unless otherwise stated. b–i Increased fibrosis and collagen deposition observed in the lungs of BLM-treated mice were attenuated by the adoptive transfer of Tregs (1 × 10⁶/mouse) on day 14 post-BLM challenge. Representative photomicrographs following hematoxylin and eosin (HE) and Masson’s trichrome staining of the right lungs from saline-treated and BLM-treated mice, with or without adoptively transferred Tregs. Magnification × 40. j The extent of lung fibrosis was measured by quantitative histology according to Ashcroft’s method on day 28 to determine the anti-fibrotic effects of Tregs in the lungs of BLM-treated mice. The adoptive transfer of Tregs on day 14 post-treatment significantly attenuated the numerical score, which was increased by BLM treatment. *P < 0.01. n = 7 mice/group. k The hydroxyproline content in the lungs was measured on day 28. The adoptive transfer of Tregs on day 14 post-treatment significantly reduced the hydroxyproline content when compared with the BLM treated group. *P < 0.05. n = 4 mice for the BLM group, n = 3 mice for the BLM + Tregs group