Characterization of gut microbial and metabolite alterations in faeces of Goto Kakizaki rats using metagenomic and untargeted metabolomic approach

Linear association of the dietary index for gut microbiota with insulin resistance and type 2 diabetes mellitus in U.S. adults: the mediating role of body mass index and inflammatory markers

Background

Gut microbiota is reported to be related to the onset of insulin resistance (IR) and type 2 diabetes mellitus (T2DM). The dietary index for gut microbiota (DI-GM) is a novel index for reflecting gut microbiota diversity. We aimed to evaluate the association of DI-GM with T2DM and IR.

Methods

This cross-sectional research comprised 10,600 participants aged ≥20 from the National Health and Nutrition Examination Survey (NHANES) 2007-2018. We employed weighted multivariable linear and logistic regression models to examine the correlation of DI-GM with T2DM and IR. Linear or nonlinear relationships were examined by restricted cubic spline (RCS) regression. Additionally, subgroup and sensitivity analyses were performed to ensure the reliability of the results. Mediation analysis explored the roles of body mass index (BMI) and inflammatory factors in these associations.

Results

Higher DI-GM were inversely associated with T2DM (OR = 0.93, 95%CI: 0.89-0.98) and IR (OR = 0.95, 95%CI: 0.91-0.99) after adjusting for confounders. DI-GM ≥ 6 group showed significantly lower risks of T2DM (OR = 0.74, 95%CI: 0.60-0.91) and IR (OR = 0.77, 95%CI: 0.62-0.95). RCS demonstrated a linear relationship between DI-GM and T2DM, as well as IR. DI-GM was also inversely correlated with the risk markers of T2DM. Mediation analysis showed that BMI and the systemic inflammation response index partly mediated the association of DI-GM with T2DM and IR, while the systemic immune-inflammation index mediated only the association with T2DM.

Conclusion

DI-GM is inversely associated with T2DM and IR, with BMI and inflammatory markers partly mediating this association.

Proteomic Analysis of the Effects of Shenzhu Tiaopi Granules on Model Rats with Type 2 Diabetes Mellitus

Background

Shenzhu Tiaopi granule (STG) has antidiabetic functions. Data-independent acquisition proteomic technology is an integral part of systems biology. Herein, proteomics was used to analyse the effects of STG on type 2 diabetes mellitus (T2DM) and the mechanism by which STG normalizes glucose metabolism.

Methods

Goto-Kakizaki (GK) T2DM model (Mod) rats, aged 15-16 weeks and with a fasting blood glucose (FBG) level of ≥11.1 mmol/L, were treated with metformin or STG for 12 weeks. Wistar rats aged 15-16 weeks were included in the control (Con) group. Body weight, FBG, total cholesterol (TC), total triglyceride (TG) levels and low-density lipoprotein (LDL-C) levels were measured, and pathological observation, Western blot analysis and data-independent acquisition proteomics of the liver were performed.

Results

Significant differences in FBG, TC, TG, LDL-C (p < 0.01) and pathological liver morphology were observed between the Mod group and Con group, whereas both metformin and STG normalized the glucose and lipid metabolism indicators (p < 0.05 or p < 0.01). In total, 5856 proteins were identified via proteomic analysis, 97 of which were significantly differentially expressed in the liver and affected fatty acid metabolism, unsaturated fatty acid biosynthesis, the peroxisome proliferator-activated receptor (PPAR) signalling pathway, pyruvate metabolism, and terpenoid backbone biosynthesis. Screening identified 10 target proteins, including perilipin-2 (Plin2), pyruvate dehydrogenase kinase 4, farnesyl diphosphate synthase (Fdps) and farnesyl-diphosphate farnesyltransferase 1. Among these proteins, the key proteins were Plin2 and Fdps, which were found to be associated with the PPAR signalling pathway and terpenoid backbone biosynthesis via relationship networks. Plin2 and Fdps are closely related to hyperglycaemia. STG can downregulate Plin2 and upregulate Fdps (p < 0.01).

Conclusion

STG ameliorated hyperglycaemia by significantly altering the expression of different proteins, especially Fdps and Plin2, in the livers of GK rats. These findings may reveal the potential of traditional Chinese medicine for treating T2DM.

Stabilization of hypoxia-inducible factor 1α and regulation of specific gut microbes by EGCG contribute to the alleviation of ileal barrier disorder and obesity

Tea polyphenols have a regulatory effect on metabolic-related diseases, however, the underlying mechanism remains elusive. Our study aims to explore the dietary intervention effect of Epigallocatechin gallate (EGCG), the major polyphenol in green tea, on obesity and intestinal barrier disorders in mice fed a high-fat diet. By supplementing with 50 mg kg-1 EGCG, we observed a significant amelioration in body weight gain, fat accumulation, and liver dysfunction. Furthermore, EGCG modulated the HFD-induced metabolomic alterations. In particular, EGCG intervention restored the ileal barrier by enhancing the expression of tight junction proteins and antimicrobial peptides. At the mechanistic level, EGCG treatment stabilized hypoxia-inducible factor 1α (HIF1α) both in vitro and in vivo. Meanwhile, EGCG significantly increased the abundance of Dubosiella and Akkermansia, along with the elevated SCFA contents. These findings suggest that the ability of EGCG to stabilize HIF1α and regulate specific gut microbes is pivotal in mitigating ileal barrier dysfunction and obesity. Moreover, serum metabolomics revealed potential biomarkers following EGCG intervention. This study supports the intake of EGCG or green tea in obesity management and offers a novel perspective for investigating the metabolic regulatory mechanism of other dietary polyphenols.

The efficacy and mechanism of Angelica sinensis (Oliv.) Diels root aqueous extract based on RNA sequencing and 16S rDNA sequencing in alleviating polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) leads to persistent anovulation, hyperandrogenism, insulin resistance, and polycystic ovary, and is mainly characterized by menstrual disorders, and reproductive dysfunction. Angelica sinensis (Oliv.) Diels root has been used in many classical formulas of traditional Chinese medicine, and is commonly used to treat various gynecological diseases.

PURPOSE

To investigate the protective effect of water extract of A. sinensis root (WEA) on PCOS rats, and the mechanism by RNA sequencing, and 16S rDNA sequencing.

METHODS

The PCOS rat model was established by letrozole combined with high-fat diet (gavage; 2 months), and treated with WEA (gavage; 2 g/kg, 4 g/kg or 8 g/kg; 1 month). To evaluate the therapeutic effect of WEA on PCOS rats, vaginal smear, hematoxylin-eosin staining, and biochemical indicators detection were performed. The rat ovarian tissue was analyzed by RNA sequencing, and the results were verified by qRT-PCR, and Western blot. 16S rDNA sequencing was used to analyze the gut microbiota of rats.

RESULTS

The results of the vaginal smear, and hematoxylin-eosin staining showed that WEA improved estrous cycle disorder, and ovarian tissue lesions. WEA (4 g/kg or 8 g/kg; 1 months) alleviated hormone disorders, insulin resistance, and dyslipidemia. RNA sequencing showed that WEA intervention significantly changed the expressions of 2756 genes, which were enriched in phosphatidylinositol3-kinase/phosphorylated protein kinase B (PI3K/AKT), peroxisome proliferator-activated receptor (PPAR), mitogen-activated protein kinase (MAPK), AMP-activated protein kinase (AMPK), and insulin signaling pathways. 16S rDNA sequencing found that WEA increased the species diversity of gut microbiota, and regulated the abundance of some microbiota (genus level: Dubosiella, Bifidobacterium, Coriobacteriaceae (UCG-002), and Treponema; species level: Bifidobacterium animalis, Lactobacillus murinus, and Lactobacillus johnsonii).

CONCLUSION

WEA regulated hormone, and glycolipid metabolism disorders, thereby relieving the PCOS induced by letrozole combined with high-fat diet. The mechanism was related to the regulation of PI3K/AKT, PPAR, MAPK, AMPK, and insulin signaling pathways in ovarian tissues, and the maintenance of gut microbiota homeostasis. Clarifying the efficacy and mechanism of WEA in alleviating PCOS based on RNA sequencing and 16S rDNA sequencing will guide the more reasonable clinical use of WEA.