Gut microbiota might mediate the benefits of high-fiber/acetate diet to cardiac hypertrophy mice

Short-Chain Fatty Acids and Their Metabolic Interactions in Heart Failure

Short-chain fatty acids (SCFAs), produced through fermentation of dietary fibers by gut bacteria, play a central role in modulating cardiovascular function and heart failure (HF) development. The progression of HF is influenced by intestinal barrier dysfunction and microbial translocation, where SCFAs serve as key mediators in the gut-heart axis. This review examines the complex metabolic interactions between SCFAs and other gut microbiota metabolites in HF, including their relationships with trimethylamine N-oxide (TMAO), aromatic amino acids (AAAs), B vitamins, and bile acids (BAs). We analyze the associations between SCFA production and clinical parameters of HF, such as left ventricular ejection fraction (LVEF), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and glomerular filtration rate (GFR). Gaining insights into metabolic networks offers new potential therapeutic targets and prognostic markers for managing heart failure, although their clinical significance needs further exploration.

Soy protein β-conglycinin ameliorates pressure overload-induced heart failure by increasing short-chain fatty acid (SCFA)-producing gut microbiota and intestinal SCFAs

BACKGROUND AND AIMS

Soybeans and their ingredients have antioxidant and anti-inflammatory effects on cardiovascular diseases. β-Conglycinin (β-CG), a major constituent of soy proteins, is protective against obesity, hypertension, and chronic kidney disease, but its effects on heart failure remain to be elucidated. We tested the effects of β-CG on left ventricular (LV) remodeling in pressure overload-induced heart failure.

METHODS

A transverse aortic constriction (TAC)-induced pressure overload was applied to the heart in 7-week-old C57BL6 male mice that were treated with β-CG, GlcNAc, or sodium propionate. Gut microbiota was analyzed by 16S rRNA sequencing. Fecal short-chain fatty acids (SCFAs) were quantified by GC-MS. The effects of oral antibiotics were examined in β-CG-fed mice.

RESULTS

β-CG ameliorated impaired cardiac contractions, cardiac hypertrophy, and myocardial fibrosis in TAC-operated mice. As β-CG is a highly glycosylated protein, we examined the effects of GlcNAc. GlcNAc had similar but less efficient effects on LV remodeling compared to β-CG. β-CG increased three major SCFA-producing intestinal bacteria, as well as fecal concentrations of SCFAs, in sham- and TAC-operated mice. Oral administration of antibiotics nullified the effects of β-CG in TAC-operated mice by markedly reducing SCFA-producing intestinal bacteria and fecal SCFAs. In contrast, oral administration of sodium propionate, one of SCFAs, ameliorated LV remodeling in TAC-operated mice to a similar extent as β-CG.

CONCLUSIONS

β-CG was protective against TAC-induced LV remodeling, which was likely to be mediated by increased SCFA-producing gut microbiota and increased intestinal SCFAs. Modified β-CG and/or derivatives arising from β-CG are expected to be developed as prophylactic and/or therapeutic agents to ameliorate devastating symptoms in heart failure.

Probing the alterations in mice cecal content due to high-fat diet

The global prevalence of obesity more than doubled between 1990 and 2022. By 2022, 2.5 billion adults aged 18 and older were overweight, with over 890 million of them living with obesity. The urgent need for understanding the impact of high-fat diet, together with the demanding of analytical methods with low energy/chemicals consumption, can be fulfilled by rapid, high-throughput spectroscopic techniques. To understand the impact of high-fat diet on the metabolic signatures of mouse cecal contents, we characterized metabolite variations in two diet-groups (standard vs high-fat diet) using FTIR spectroscopy and multivariate analysis. Their cecal content showed distinct spectral features corresponding to high- and low-molecular-weight metabolites. Further quantification of 13 low-molecular-weight metabolites using liquid chromatography showed significant reduction in the production of short chain fatty acids and amino acids associated with high-fat diet samples. These findings demonstrated the potential of spectroscopy to follow changes in gut metabolites.

Mechanism of sodium butyrate, a metabolite of gut microbiota, regulating cardiac fibroblast transdifferentiation via the NLRP3/Caspase-1 pyroptosis pathway

BACKGROUND

Cardiac fibroblasts (CFs) are activated after initial injury, and then differentiate into myofibroblasts (MFs), which play a pivotal role as the primary mediator cells in pathological remodeling. Sodium butyrate (NaB), being a metabolite of gut microbiota, exhibits anti-inflammatory property in local therapies on sites other than the intestine. Thus, this study aimed to probe the mechanism by which NaB regulates CFs transdifferentiation through the NLRP3/Caspase-1 pyroptosis pathway.

METHODS

CFs were cultured in vitro and induced into MFs by TGFβ1. CFs were identified by immunofluorescence labelling technique of vimentin and α-SMA, followed by treatment with NaB or NLRP3 inflammasome inhibitor (CY-09) and its activator [nigericin sodium salt (NSS)]. The expression levels of α-SMA, GSDMD-N/NLRP3/cleaved Caspase-1 proteins, and inflammatory factors IL-1β/IL-18/IL-6/IL-10 were determined using immunofluorescence, Western blot and ELISA. Cell proliferation and migration were evaluated using the CCK-8 assay and the cell scratch test, respectively.

RESULTS

Following the induction of TGFβ1, CFs exhibited increased expression levels of α-SMA proteins and IL-6/IL-10, as well as cell proliferative and migratory abilities. TGFβ1 induced CFs to differentiate into MFs, while NaB inhibited this differentiation. NaB inactivated the NLRP3/Caspase-1 pyroptosis pathway. CY-09 demonstrated inhibitory effects on the NLRP3/Caspase-1 pyroptosis pathway, leading to a reduction in TGFβ1-induced CFs transdifferentiation. NSS activated the NLRP3/Caspase-1 pyroptosis pathway, and thus partially counteracting the inhibitory effect of intestinal microbiota metabolite NaB on CFs transdifferentiation.

CONCLUSION

NaB, a metabolite of the gut microbiota, inhibited the activation of the NLRP3/Caspase-1 pyroptosis pathway in TGFβ1-induced CFs, repressed the transdifferentiation of CFs into MFs.

Short-chain fatty acids in breast milk and their relationship with the infant gut microbiota

Introduction

The short-chain fatty acids (SCFAs) contained in breast milk play a key role in infant growth, affecting metabolism and enhancing intestinal immunity by regulating inflammation.

Methods

In order to examine the associations between the microbiota and SCFA levels in breast milk, and explore the roles of SCFAs in regulating the infant gut microbiota, we enrolled 50 paired mothers and infants and collected both breast milk and infant fecal samples. Breast milk SCFA contents were determined by UPLC-MS, and whole genome shotgun sequencing was applied to determine the microbial composition of breast milk and infant feces. The SCFA levels in breast milk were grouped into tertiles as high, medium, or low, and the differences of intestinal microbiota and KEGG pathways were compared among groups.

Results

The results demonstrated that breast milk butyric acid (C4) is significantly associated with Clostridium leptum richness in breastmilk. Additionally, the specific Bifidobacterium may have an interactive symbiosis with the main species of C4-producing bacteria in human milk. Women with a low breast milk C4 tertile are associated with a high abundance of Salmonella and Salmonella enterica in their infants' feces. KEGG pathway analysis further showed that the content of C4 in breast milk is significantly correlated with the infants' metabolic pathways of lysine and arginine biosynthesis.

Discussion

This study suggests that interactive symbiosis of the microbiota exists in breast milk. Certain breast milk microbes could be beneficial by producing C4 and further influence the abundance of certain gut microbes in infants, playing an important role in early immune and metabolic development.