Gut Microbiota and Bile Acids Mediate the Clinical Benefits of YH1 in Male Patients with Type 2 Diabetes Mellitus: A Pilot Observational Study

Abstract

Our previous clinical trial showed that a novel concentrated herbal extract formula, YH1 (Rhizoma coptidis and Shen-Ling-Bai-Zhu-San), improved blood glucose and lipid control. This pilot observational study investigated whether YH1 affects microbiota, plasma, and fecal bile acid (BA) compositions in ten untreated male patients with type 2 diabetes (T2D), hyperlipidemia, and a body mass index ≥ 23 kg/m². Stool and plasma samples were collected for microbiome, BA, and biochemical analyses before and after 4 weeks of YH1 therapy. As previous studies found, the glycated albumin, 2-h postprandial glucose, triglycerides, total cholesterol, and low-density lipoprotein cholesterol levels were significantly improved after YH1 treatment. Gut microbiota revealed an increased abundance of the short-chain fatty acid-producing bacteria Anaerostipes and Escherichia/Shigella. Furthermore, YH1 inhibited specific phylotypes of bile salt hydrolase-expressing bacteria, including Parabacteroides, Bifidobacterium, and Bacteroides caccae. Stool tauro-conjugated BA levels increased after YH1 treatment. Plasma total BAs and 7α-hydroxy-4-cholesten-3-one (C4), a BA synthesis indicator, were elevated. The reduced deconjugation of BAs and increased plasma conjugated BAs, especially tauro-conjugated BAs, led to a decreased glyco- to tauro-conjugated BA ratio and reduced unconjugated secondary BAs. These results suggest that YH1 ameliorates T2D and hyperlipidemia by modulating microbiota constituents that alter fecal and plasma BA compositions and promote liver cholesterol-to-BA conversion and glucose homeostasis.

Keywords: Chinese herbal medicine; YH1; bile acids; gut microbiota; type 2 diabetes.

Figure 1

Oral YH1 modulated the composition of gut microbiota in men with type 2 diabetes and hyperlipidemia. (a) Chao1 and Shannon indices were used to analyze the α-diversity of fecal microbiota before (red circles) and after (green squares) YH1 treatment in ten patients. (b) The β-diversity of fecal microbiota at baseline and after YH1 treatment was determined by principal coordinate analysis (PCoA) based on the Bray-Curtis dissimilarity index. Significant changes in the fecal microbiota at the (c) genus and (d) species level before and after YH1 treatment are presented. Genus and species names in brown or blue font represent significant enrichment or depletion of bacteria after YH1 treatments, respectively. Statistical significance (* p < 0.05; ** p < 0.01) were detected by the Wilcoxon signed-rank test.

Figure 2

YH1 altered plasma bile acid profiles in men with type 2 diabetes and hyperlipidemia. The concentration of each bile acid in the plasma of ten patients before (red) and after (green) YH1 treatment is represented by a box-and-whisker plot. The line inside the box represents the median value, and the box is between the first and third quartiles. The ends of the whiskers represent the minimum and maximum values. Wilcoxon signed-rank test was used, and * p < 0.05 was considered statistically significant.

Figure 3

Changes in the composition of bile acids (BAs) of various categories in plasma before and after treatment with YH1. The concentrations of classified BAs in plasma before (red circles) and after (green squares) YH1 treatment in the ten patients are shown as scatter plots, with lines representing median values. Statistical differences (* p < 0.05) were detected by the Wilcoxon signed-rank test. After four weeks of YH1 treatment, the levels of (a) 12α-hydroxylated BAs and non-12α-hydroxylated BAs, (b) primary BAs, (c) conjugated BAs, and (d) glyco (G)- and tauro (T)-conjugated BAs in plasma were all significantly elevated. (c) Unconjugated BAs and (d) G/T ratio of conjugated BAs were significantly reduced. 12α-OH BAs, 12α-hydroxylated bile acids; Non-12α-OH BAs, non-12α-hydroxylated bile acids.

Figure 4

Changes in total and classification ratios of bile acids (BAs) in plasma and feces after YH1 treatment. Total BAs and classification ratios of BAs in plasma and feces before (red circles) and after (green squares) YH1 treatment in the ten patients are shown as scatter plots. The line in the graph represents the median value. The Wilcoxon signed-rank test was used to determine whether there was a statistical difference before and after treatment (* p < 0.05). (a) Total plasma BAs increased significantly after YH1 treatment. (b) The ratio of 12α-hydroxylated to non-12α-hydroxylated BAs didn’t show significant change. Changes in the ratio of BA classification were only significantly elevated in plasma (c) conjugated/unconjugated BAs and (d) primary/secondary BAs. (e) Total stool BAs had no significant change before and after YH1 treatment. In addition, no significant difference was found in the analysis of fecal BA profiles (f–h) before and after treatment. 12α-OH/non-12α-OH BAs, 12α-hydroxylated/non-12α-hydroxylated bile acids.