Baicalin Regulates Autophagy to Intervene with Intestinal Acute Graft-Versus-Host Disease via AMPK/Mtor Pathway and Abnormal Intestinal Flora

Abstract Acute graft versus host disease (aGVHD) is the main complication of allogeneic hematopoietic stem cell transplantation and the main cause of death. To verify if baicalin can protect the intestinal mucosal barrier by regulating abnormal autophagy and interfering with acute intestinal graft-versus-host disease, a mouse model of aGVHD was established. CB6F1 mice were transplanted with a mononuclear cell suspension from Balb/c donor mice bone marrow and spleen via vein injection after treatment with 60co X rays. After treatment with different doses of baicalin for 15 days, survival time, survival time,the serum level of TNF-α and IL-10, the autophagy markers from intestinal and bacterial flora were detected.A intestinal barrier dysfunction cell model was also used to verify the effect of baicalin.The results showed that baicalin could significantly prolong survival time, reduced aGVHD score compared to the model control group, significantly reduce TNF-α level, and increase IL-10 level. TEM examination showed that baicalin treatment increased the number of autophagic vacuoles and led to recovery of mitochondrial structure in the intestinal mucosal epithelial cells of mice and in Caco-2 cells. Western blot results showed that baicalin treatment enhanced autophagy in vivo by regulating the AMPK/mTOR autophagy pathway. Similar results were observed in vitro in Caco-2 cells. Furthermore, the effect of baicalin was reduced after combined treated with autophagy inhibitors 3-MA.The results of intestinal microbial sequencing also confirmed that there were significant changes in the type and quantity of bacterial flora before and after the application of baicalin. Baicalin can reduce the severity of intestinal acute graft-versus-host disease by regulating autophagy with influencing the unbalanced inflammatory cytolines and bacterial flora, which may be a new treatment for aGVHD.