[Protective effect and mechanism of rapamycin on pulmonary fibrosis induced by Chlormethine in mice].

To evaluate the therapeutic effect and mechanism of rapamycin (RAPA) on pulmonary fibrosis induced by chlormethine in C57BL/6N mice. Based on body weight, the 18-20 g C57BL/6N mice were randomly divided into five groups: control group, chlormethine group, chlormethine+dexamethasone (1 mg/kg) group, chlormethine+RAPA (1 mg/kg) group and chlormethine+RAPA (2 mg/kg) group, with ten mice in each group. Mice were put to death on the 21st day after the first administration of chlormethine. HE staining and Masson staining were used to observe the pathological changes and degree of fibrosis in the lung tissue of mice, and RT-PCR was used to detect collagen Ⅰ, E-cadherin, vimentin, and α-SMA mRNA expression. After 21 days of administration of chlormethine to mice, significant pulmonary fibrosis characteristics were observed in the lung tissue of the mice. Compared with the chlormethine group, the weight of mice in the chlormethine+dexamethasone (1 mg/kg) group, chlormethine+RAPA (1 mg/kg) group and chlormethine+RAPA (2 mg/kg) group, significantly increased (P<0.05). Compared with the chlormethine group, the expression of pulmonary fibrosis-related indicators (collagen Ⅰ, E-cadherin, vimentin, and α-SMA) significantly improved (P<0.05) in the chlormethine+dexamethasone (1 mg/kg) group, chlormethine+RAPA (1 mg/kg) group and chlormethine+RAPA (2 mg/kg) group. Compared with the chlormethine group, the pathological changes and collagen deposition in the lung tissue of mice in the chlormethine+dexamethasone (1 mg/kg) group, chlormethine+RAPA (1 mg/kg) group and chlormethine+RAPA (2 mg/kg) group, were significantly improved. Transcriptome analysis of the lung tissue of mice revealed that RAPA treatment of chlormethine-induced pulmonary fibrosis might be related to NF-kappa B signaling pathway. Compared with the chlormethine group, the mRNA expression of p65 in the lung tissue of mice in the chlormethine+dexamethasone (1 mg/kg) group, chlormethine+RAPA (1 mg/kg) group and chlormethine+RAPA (2 mg/kg) group, significantly decreased (P<0.01). RAPA has a protective effect on pulmonary fibrosis induced by chlormethine in mice. Its efficacy is comparable to that of dexamethasone, which is currently being used in clinical practice. It is a new alternative therapy, and its mechanism may be related to inhibiting the activation of the NF-kappa B signaling pathway.