OBJECTIVE  To observe the clinical efficacy of Lichang beverage in the treatment of diarrhea-type irritable bowel syndrome (IBS-D) based on the bacteria-brain-intestine axis and its effects on serum brain-gut peptide and intestinal flora, and to explore the possible mechanism of efficacy.

  METHODS  A total of 66 IBS-D patients with liver depression and spleen deficiency were randomly divided into the Chinese medicine group (44 patients) and the western medicine group (22 patients) in a 2 ∶ 1 ratio. In the Chinese medicine group, Lichang beverage was given orally. However, the patients in the western medicine group were administrated with Bifico combination with Dicetel. The treatment course lasted four weeks. Besides, the changes in the IBS-SSS scores of both groups were evaluated before treatment, as well as after two weeks and four weeks of treatment. The changes in the traditional Chinese medicine (TCM) syndrome scores of both groups were observed before and after treatment. In addition, the expression levels of serum brain-gut peptide indexes substance P (SP) and serotonin (5-HT) and the composition of intestinal flora were measured.

  RESULTS  The IBS-SSS scores of both groups were reduced significantly after two weeks and four weeks of treatment (P < 0.01), but the results in the Chinese medicine group were better than those in the western medicine group (P < 0.01). After four weeks of treatment, the total TCM syndrome scores of both groups were reduced significantly (P < 0.01), while the results in the Chinese medicine group were better than those in the western medicine group (P < 0.01). In addition, the clinical healing rate and total effective rate of the Chinese medicine group were higher than those of the western medicine group (P < 0.05, P < 0.01). After treatment, the serum SP level in both groups were reduced significantly (P < 0.05), and the serum 5-HT level in the Chinese medicine group were reduced notably (P < 0.01), but there was no significant difference between the two groups (P>0.05). The α diversity analysis indicated that the richness of intestinal flora in both groups decreased to different degrees after treatment (P < 0. 05, P < 0.01), and the diversity of flora in the western medicine group was reduced compared with that before (P < 0. 05), while there was no significant difference in the Chinese medicine group (P>0. 05). The PCoA analysis showed that the composition of microbial community in both groups changed significantly (P < 0. 05), and there were significant differences between groups (P < 0.01). Among them, the biomarkers with significant advantages after treatment in the Chinese medicine group were Clostridium_sensu_stricto_1 and Bacteroides_plebeius. However, the Biomarkers with significant advantages after treatment in the western medicine group were ruminococcus_gnavus_group. The functional prediction of the flora suggested that the main pathway of IBS-D treatment by Lichang beverage was glucose metabolism-related. Besides, no drug-related adverse reactions were observed in either group during the treatment course.

  CONCLUSION  The efficacy of Chinese herbal medicine compound — Lichang beverage in treating IBS-D with liver depression and spleen deficiency is accurate and safe. Its mechanism may be related to the regulation of serum brain-gut peptide level, adjustment of intestinal flora structure, correction of flora imbalance, and regulation of glucose metabolism-related flora.