Leonurine Negatively Modulates T Cells Activity By Suppressing RAG2 in Lung Fibrosis

Background: The key transformed T cells transcription factor RAG2 is regulated during inflammation to allow for the acquisition of effector T cells functions. Here, the present study was designed to investigate whether stress signals elicited by leonurine (LEO) could lead to the degradation of RAG2 through AKT signal in lung fibrosis. <br><br>Methods: There were 40 female mice randomly divided into 5 groups (Group I-V): Normal group, Bleomycin (BLM), BLM LEO 50mg/kg/d, BLM LEO100mg/kg/d and BLM LEO50mg/kg/d LY294002. At 7, 14 and 28 days after modeling, pathomorphological, apoptosis, CD3 T cells, the expression of RAG2, TGFβ1 and AKT signal were detected by immunohistochemistry or western blot. <br><br>Findings: Our results demonstrated T lymphocytes were reduced sharply in leonurine treated mice compared with other groups. Besides, AKT signal was greatly inhibited in BLM group and activated with leonurine treatment in Group III-IV, especially at 14th day. In addition, RAG2 was attunuated by leonurine on the 14th day- and 28th day-mold mice. Remarkably, the high-dose of leonurine did not have greater protective efficacy compared with the low-dose group of leonurine in degrees of pulmonary fibrosis, T cells inactivation and apoptosis in alveolar cells. The best dose-effect of LEO was attained in 50mg/kg/d in pulmonary fibrosis. <br><br>Interpretation: The critical role of leonurine in promoting T cells inactivation by suppressing RAG2 may provide a potential therapeutic target for the intervention against pulmonary fibrosis.<br><br>Funding Statement: This work was financially supported by the National Natural Science Foundation of China (no.81800070 to Xiaoting Lv and no.81871293 to Qicai Liu), the Nursery Foundation of Fujian Medical University (no.2015MP026 to Xiaoting Lv) and a grant from the Sail Foundation of Fujian Medical University (no.2016QH063 to Xiaoting Lv). Youth Research Fund Project of Fujian Provincial Health and Family Planning Commission (no.2017-1-43 to Yongping Zhu).<br><br>Declaration of Interests: The authors have no competing interests to declare.<br><br>Ethics Approval Statement: This animal experiment was approved by the Experimentation Ethics Committee on Animal Rights Protection of Fujian Medical University. During the experiments, the animals were treated in compliance with the “Guiding Opinions on the Ethical Treatments of Laboratory Animals” published by the Ministry of Science and Technology in 2006. All procedures strictly followed the National Institutes of Health guidelines for the care and use of laboratory animals.