Traditional Chinese herbal formulas modulate gut microbiome and improve insomnia in patients with distinct syndrome types: insights from an interventional clinical study

Abstract

Background: Traditional Chinese medicine (TCM) comprising herbal formulas has been used for millennia to treat various diseases, such as insomnia, based on distinct syndrome types. Although TCM has been proposed to be effective in insomnia through gut microbiota modulation in animal models, human studies remain limited. Therefore, this study employs machine learning and integrative network techniques to elucidate the role of the gut microbiome in the efficacies of two TCM formulas - center-supplementing and qi-boosting decoction (CSQBD) and spleen-tonifying and yin heat-clearing decoction (STYHCD) - in treating insomnia patients diagnosed with spleen qi deficiency and spleen qi deficiency with stomach heat.

Methods: Sixty-three insomnia patients with these two specific TCM syndromes were enrolled and treated with CSQBD or STYHCD for 4 weeks. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index (ISI) every 2 weeks. In addition, variations in gut microbiota were evaluated through 16S rRNA gene sequencing. Stress and inflammatory markers were measured pre- and post-treatment.

Results: At baseline, patients exhibiting only spleen qi deficiency showed slightly lesser severe insomnia, lower IFN-α levels, and higher cortisol levels than those with spleen qi deficiency with stomach heat. Both TCM syndromes displayed distinct gut microbiome profiles despite baseline adjustment of PSQI, ISI, and IFN-α scores. The nested stratified 10-fold cross-validated random forest classifier showed that patients with spleen qi deficiency had a higher abundance of Bifidobacterium longum than those with spleen qi deficiency with stomach heat, negatively associated with plasma IFN-α concentration. Both CSQBD and STYHCD treatments significantly improved sleep quality within 2 weeks, which lasted throughout the study. Moreover, the gut microbiome and inflammatory markers were significantly altered post-treatment. The longitudinal integrative network analysis revealed interconnections between sleep quality, gut microbes, such as Phascolarctobacterium and Ruminococcaceae, and inflammatory markers.

Conclusion: This study reveals distinct microbiome profiles associated with different TCM syndrome types and underscores the link between the gut microbiome and efficacies of Chinese herbal formulas in improving insomnia. These findings deepen our understanding of the gut-brain axis in relation to insomnia and pave the way for precision treatment approaches leveraging TCM herbal remedies.

Keywords: gut microbiome; gut-brain axis; herbal formula; insomnia; longitudinal integrative network; traditional Chinese medicine syndrome.

Figure 1

Clinical interventional trial flow diagram. STYHCD, spleen-tonifying and yin heat-clearing decoction; CSQBD, center-supplementing and qi-boosting decoction.

Figure 2

Baseline gut microbial profiles in insomnia patients with different TCM syndromes. (A) Principal coordinate analysis based on unweighted UniFrac distance. Adjusted P-value (P.adj) was obtained after controlling the baseline scores of PSQI, ISI, and IFN-α using the Adonis test. (B) Heatmap of the top 22 differential gut microbial species between the two treatment groups at the baseline and their correlations with clinical measurements. The abundance of each ASV was averaged within each group. Correlation coefficient was obtained with spearman correlation. FDR_BH, FDR-corrected p-value obtained using the Benjamini-Hochberg method to adjust for multiple comparisons. STYHCD, spleen-tonifying and yin heat-clearing decoction; CSQBD, center-supplementing and qi-boosting decoction; ASV, amplicon sequence variant.

Figure 3

Both herbal formula interventions significantly improved insomnia. (A) Changes in PSQI and ISI scores over time following intervention with two herbal formulas. (B) Longitudinal effects on PSQI and ISI scores between two treatments and within each treatment. (C) Long-term sustainability of the effectiveness of treatments compared to baseline. FDR_BH, FDR-corrected p-value obtained using the Benjamini-Hochberg method to adjust for multiple comparisons. The vertical dashed line represents the FDR_BH threshold of 0.05. P-values were determined using linear mixed models. PSQI, Pittsburgh Sleep Quality Index; ISI, Insomnia Severity Index; STYHCD, spleen-tonifying and yin heat-clearing decoction; CSQBD, center-supplementing and qi-boosting decoction.

Figure 4

Temporal alterations in the gut microbiome of insomnia patients over time after receiving two herbal formula treatments. (A) Principal coordinate analysis based on Unweighted UniFrac distance. (B) Clustering of gut microbiota based on inter-group distances obtained through MANOVA test using the initial 31 PCs (explained >80% variation) of unweighted UniFrac PCoA. STYHCD, spleen-tonifying and yin heat-clearing decoction; CSQBD, center-supplementing and qi-boosting decoction.

Figure 5

Key gut microbial species altered by herbal formula treatments over time. (A) Heatmap of the top 14 gut microbial species altered by STYHCD treatment overtime. (B) Heatmap of the top 20 gut microbial species altered by CSQBD treatment overtime. STYHCD, spleen-tonifying and yin heat-clearing decoction; CSQBD, center-supplementing and qi-boosting decoction.

Figure 6

Longitudinal networks involved in insomnia improvement, key gut microbial species, and plasma biomarkers. (A) Longitudinal integrative network of STYHCD. (B) Longitudinal integrative network of CSQBD. STYHCD, spleen-tonifying and yin heat-clearing decoction; CSQBD, center-supplementing and qi-boosting decoction.