Gut microbiota mediate the alleviation effect of Xiehuo-Guzheng granules on β cell dedifferentiation in type 2 diabetes mellitus

Background

Type 2 diabetes mellitus (T2DM) is a worldwide public health problem characterized by a progressive decline in β cell function. In traditional Chinese medicine (TCM) theory, ‘fire’ and ‘healthy qi deficiency’ are important pathogeneses of T2DM, and purging ‘fire’ and reinforcing the ‘healthy qi’ (Pinyin name: Xiehuo-Guzheng, XHGZ) are important method of treatment. Over the years, we have observed its benefit for diabetes. However, the underlying mechanisms remain unclear.

Purpose

To investigate the mechanism of XHGZ granules against β cell dedifferentiation in T2DM based on gut microbiota.

Methods

Rats with T2DM, induced by intraperitoneal injection of streptozotocin after eight weeks of high-fat diet, were randomly allocated to receive XHGZ granules, metformin, or distilled water for eight consecutive weeks. Changes in metabolic parameters, β cell dedifferentiation, inflammatory cytokines, gut microbiota, and microbial metabolites (lipopolysaccharide (LPS) and short-chain fatty acids (SCFAs)), were detected. Furthermore, faecal microbiota transplantation (FMT) was performed to confirm the anti-diabetic effect of XHGZ granule-regulated gut microbiota in pseudo-germ-free T2DM rats.

Results

XHGZ granules significantly ameliorated hyperglycaemia, improved islet function and pathology, and reduced β cell dedifferentiation and pro-inflammatory cytokines in T2DM rats. 16S rRNA sequencing revealed that XHGZ granules decreased the LPS-containing microbiota (e.g., Colidextribacter, Desulfovibrionaceae, and Morganella) and increased the SCFAs-producing bacteria (e.g., Prevotella, Alloprevotella, and Muribaculaceae) and Lactobacillus_intestinalis. Correspondingly, it strengthened intestinal barrier, lowered LPS, and elevated acetic and butyric acids. Tax4Fun analysis indicated that XHGZ granules restored abnormal metabolism, lipopolysaccharide biosynthesis, and pantothenate and CoA biosynthesis. Moreover, the XHGZ granule-regulated microbiota also exhibited the effects of anti-diabetes, anti-β cell dedifferentiation, and anti-inflammation along with the reduction of LPS and the increase of SCFAs in pseudo-germ-free T2DM rats.

Conclusion

Our results show that XHGZ granules alleviate β cell dedifferentiation via regulating gut microbiota and their metabolites in T2DM, suggesting its potential as a promising complementary treatment for T2DM. As far as we know, there are very few studies on the alleviation of β cell dedifferentiation by TCM, and investigations into the mechanism from the perspective of intestinal flora and microbial metabolites are yet to be reported.