RESUMEN
ObjectiveMolecular docking and animal experiments were employed to explore the protective effect and mechanism of Da Chengqitang （DCQD） on intestinal barrier in septic mice. MethodText mining method was used to screen the active ingredients in DCQD. AutoDock Tools and Discovery Studio were used to study the interactions of active components with the core target proteins ［claudin-1， tumor necrosis factor （TNF）-α， interleukin （IL）-6， endogenous antimicrobial peptide mCRAMP， Toll-like receptor 4 （TLR4）， and myeloid differentiation primary response gene 88 （MyD88）］ in sepsis. Fifty C57BL/6 mice were randomized into sham， model， low- and high-dose （4 g∙kg-1 and 8 g∙kg-1） DCQD， and ulinastatin groups （n=10）. Before， during， and after the day of modeling surgery， each group was administrated with corresponding drugs. The mice in other groups except the model group were subjected to modeling by cecal ligation and puncture. Enzyme-linked immunosorbent assay （ELISA） was used measure the serum level of D-lactic acid to assess intestinal mucosa permeability. Hematoxylin-eosin staining was employed to observe the histopathological changes in the ileum and assess the intestinal mucosal damage and inflammatory infiltration. Western blotting was employed to determine the expression levels of tight junction proteins claudin-1 and occludin in the ileal tissue， which were indicative of the bowel barrier function. The TNF-α and IL-6 levels were measured by ELISA to assess the intestinal inflammation. The expression of mCRAMP in the ileal tissue was observed by immunohistochemistry. The mRNA levels of mCRAMP， TLR4， and MyD88 in mouse ileal tissue were determined by Real-time polymerase chain reaction， on the basis of which the mechanism of DCQD in protecting the intestinal barrier of septic mice was explored. ResultMolecular docking results showed that most of the 10 active ingredients of DCQD that were screened out by text mining could bind to sepsis targets by van der Waals force， hydrogen bonding， and other conjugated systems. The results of animal experiments showed that compared with the model group， low- or high-dose DCQD lowered the D-lactic acid level in the serum （P<0.01）， alleviated damage to the ileal tissue and mucosal edema， protected the small intestine villus integrity， reduced inflammatory cell infiltration， promoted the expression of claudin-1 （P<0.01）， lowered the IL-6 level （P<0.01）， up-regulated the mRNA and protein levels of mCRAMP （P<0.01）， and down-regulated the mRNA and protein levels of TLR4 and MyD88 （P<0.01） in the ileal tissue. In addition， high-dose DCQD lowered the TNF-α level and promoted the expression of occludin in the ileum tissue （P<0.01）， and low-dose DCQD up-regulated the protein level of occludin in the ileum tissue （P<0.05）. ConclusionDCQD has a protective effect on intestinal barrier in septic mice. It can reduce intestinal inflammation， repair intestinal mucosal damage， improve the tight junction protein level， and reduce intestinal mucosal permeability by up-regulating the mRNA and protein levels of mCRAMP and the down-regulating the expression of genes in the TLR4/MyD88 pathway.