The combination of four main components in Xuebijing injection improved the preventive effects of Cyclosporin A in acute graft-versus-host disease mice by protecting intestinal microenvironment.

Acute graft-versus-host disease (aGVHD) is a major life-threatening complication after Allogeneic Hematopoietic Stem Cell Transplant (allo-HSCT). Although a series of immunosuppressant agents are routinely used as the first-line prevention, the morbidity and mortality rate remains high in allo-HSCT recipients. Our previous work indicated that combining Xuebijing (XBJ) with Cyclosporin A (CSA) is superior to CSA alone in preventing aGVHD. However, it was not clear which compounds in XBJ may prevent aGVHD. Whether the effective compounds in XBJ can be safely combined with CSA to prevent GVHD remain to be evaluated. Here, we accessed whether the combination of four main components in XBJ (C0127) had the same efficacy as XBJ in preventing aGVHD. In addition, the effectiveness of a novel combination therapy (C0127 + CSA) on aGVHD prophylaxis was evaluated using 16 s rRNA sequencing and RNA sequencing approaches in vitro and in vivo. In aGVHD mice, C0127 enhanced the preventive effects of CSA including decreasing mortality, maintaining weight, reducing GVHD score and reducing the expression of IL-6 and TNF-α in serum. Fatal GVHD is a frequent consequence of intestinal tract damage. We found combining C0127 with CSA alleviated the gut damage and maintained the normal physiological function of intestine by H&E staining, intestinal permeability and short chain fatty acid (SCFA) assays. Next, 16 S sequencing analysis of feces showed the combination treatment maintained the intestinal microbial diversity, normalized the intestinal microorganism and prevented flora disorder by reducing the relative abundances of Escherichia coli and Enterococcus. Further, RNA-seq analysis of colonic epithelium revealed C0127 combined with CSA chiefly regulated chemokines and cytokines in IL-17 signaling pathway. The combination treatment reduced the expression of G-CSF and its effector STAT3 (an axis that aggravated gut inflammation and flora disorder) in gut epithelium on mRNA and protein level. These findings indicated that C0127 improved the prevention of CSA in aGVHD mice partially by protecting the gut from damage through normalizing G-CSF signaling, which regulates the intestinal microbiota and the integrity of the epithelial barrier.