Damp-heat syndrome is one of the common syndromes of various clinical diseases.Current studies have shown that intestinal flora is closely related to damp-heat syndrome,but the specific molecular biological mechanism related to intestinal flora and damp-heat syndrome is not yet clear.In this paper,the molecular biological mechanism of damp-heat syndrome is discussed from the perspective of intestinal flora related signaling pathways,so as to provide ideas for the essence of damp-heat syndrome and clinical diagnosis and treatment.

ObjectiveTo investigate the changes of intestinal microbiota in type 2 diabetic diarrhea （T2DD） patients with dampness-heat syndrome and spleen-kidney deficiency syndrome. MethodT2DD patients who were admitted to the Department of Endocrinology Ⅰ of the Affiliated Hospital of Shaanxi University of Chinese Medicine from March 2020 to May 2021 were selected， including 14 patients with type 2 diabetes mellitus （T2DM）， 12 T2DD patients with dampness-heat syndrome， and 13 T2DD patients with spleen-kidney deficiency syndrome. Twelve healthy subjects receiving medical examination were selected as control group. Their body mass index （BMI）， fasting plasma glucose （FPG）， 2 h postprandial blood glucose （2 h PBG） and glycosylated hemoglobin （HbA1c） were compared. Fecal samples were collected for DNA extraction to build a database. High-throughput 16S rDNA sequencing was used to compare the composition of intestinal microbiota and the differential bacteria among the four groups. ResultCompared with the conditions in control group， the levels of FPG， 2 h PBG and HbA1c in the other groups were increased （P<0.05）. Alpha diversity showed no significant difference in species richness， evenness and diversity of intestinal microbiota among the groups. Beta diversity indicated that intestinal microbiota tended to be consistent in each group， and there was no marked difference between groups. The top 5 phylum by relative abundance were Bacteroidetes，Proteobacteria， Firmicutes， Actinobacteria， and Fusobacteria， among which，Bacteroidetes， Proteobacteria and Firmicutes were dominant. Compared with the control group， the three diabetic groups had elevated relative abundance of Bacteroidetes while decreased relative abundance of Firmicutes. The relative abundance of Actinomycetes in spleen-kidney deficiency T2DD group was significantly higher than that in the other groups， and the relative abundance of Firmicutes and Fusobacteria in the dampness-heat T2DD group was significantly lower than that in the other groups. At the genus level， the top 10 bacteria by relative abundance were Phocaeicola， Bacteroides， Pseudescherichia， Prevotella， Bifidobacterium， Faecalibacterium， Fusobacterium， Roseburia， Citrobacter， and Cetobacterium. LEfSe analysis revealed that the relative abundance of Prevotella， Mediterraneibacter， Parabacteroides， and Fusicatenibacter in diabetic patients was remarkably higher than that in healthy patients. Bacteroides and Sutterella might be the characteristic microbiota of T2DD patients with dampness-heat syndrome， while Faecalibacterium， Limosilactobacillus， Eubacterium， Gemmiger， Enterocloster， Alistipes， Parasutterella and Oscillibacter might be the characteristic microbiota of T2DD patients with spleen-kidney deficiency syndrome. ConclusionBacteroides and Parasutterella might be the characteristic microbiota of T2DD patients with dampness-heat syndrome and spleen-kidney deficiency syndrome， respectively. This paper provided reference for studying the mechanism， diagnosis and treatment of modern traditional Chinese medicine for T2DD of dampness-heat type and spleen-kidney deficiency type.