The cardiac protection of Baoyuan decoction via gut-heart axis metabolic pathway

Background: Gut-heart axis has emerged as a novel concept to provide new insights into the complex mechanisms of heart failure (HF) and offer new therapeutic targets. Cardiac hypertrophy (CH) is one of the etiological agents contributing to the development of HF. Baoyuan Decoction (BYD), a traditional Chinese medicine (TCM) formula, exhibits unambiguous effects on treating CH and preventing HF. Previously, we have reported that BYD-targeted endogenous metabolites are potentially linked to gut microbiota metabolism, but the contribution of gut microbiota and metabolic interaction to the cardioprotective efficacy of BYD remains to be elucidated. Purpose: To investigate whether the gut microbiota plays a key role in anti-CH effects of BYD. Study design: A comprehensive strategy via incorporating pharmacodynamics, microbiomics, metabolomics, and microflora suppression model was adopted to investigate the links between the microbiota-host metabolic interaction and BYD efficacy in CH rats. Method: Firstly, the efficacy evaluation of BYD in treating chronic isoproterenol (ISO)-induced CH rats was performed by using multiple pharmacodynamic approaches. Then, the fecal metabolomics and 16S rRNA sequencing techniques were used to obtain the microbial and metabolic features of BYD against CH. After that, the potential gut-heart axis-based mechanism of BYD against CH was predicted by bioinformatic network analysis and validated by multiple molecular biology approaches. Finally, the antibiotics (AB)-induced gut microbiota suppression was employed to investigate whether the anti-CH effects of BYD is associated with the gut microflora. Results: The fecal microbial communities and metabolic compositions were significantly altered in ISO-induced CH rats, while BYD effectively ameliorated the CH-associated gut microbiota dysbiosis, especially of Firmicutes and Bacteroidetes, and time-dependently alleviated the disturbance of fecal metabolome and reversed the changes of key CH and gut microbiota-related metabolites, such as short/medium chain fatty acids, primary/secondary bile acids, and amino acids. The mechanism study showed that the anti-CH effect of BYD was related to inhibition of the derivatives of arginine and tryptophan and their downstream pro-hypertrophic, pro-inflammatory, and pro-oxidant signaling pathways. The following microflora suppression test showed that BYD-mediated myocardial protection was decreased either in pharmacodynamics or in metabolic modulation. Conclusion: This study demonstrates that the protection of BYD against CH is partially gut microbiota dependent, and the regulatory effects of gut metabolism-related tryptophan and arginine derivatives is an important cardioprotection mechanism of BYD.