Differential Expression of FXR and Genes Involved in Inflammation and lipid Metabolism Indicate Adipose Tissue Dysfunction in Gestational Diabetes

Jingangteng capsules ameliorate liver lipid disorders in diabetic rats by regulating microflora imbalances, metabolic disorders, and farnesoid X receptor

BACKGROUND

The plant Smilax china L., also known as Jingangteng, is suspected of regulating glucose and lipid metabolism. Jingangteng capsules (JGTCs) are commonly used to treat gynecological inflammation in clinical practice. However, it is not clear whether JGTCs can regulate glucose and lipid metabolism, and the mechanism is unclear.

PURPOSE

To investigate the impact and mechanism of action of JGTCs on diabetes and liver lipid disorders in rats.

METHODS

The chemical constituents of JGTCs were examined using ultra-high-performance liquid chromatography with quadrupole time-of-flight mass spectrometry. A high-fat diet and streptozotocin-induced diabetes model was used to evaluate anti-diabetic effects by assessing blood glucose and lipid levels and liver function. The mechanism was explored using fecal 16S rRNA gene sequencing and metabolomics profiling, reverse transcription-quantiative polymerase chain reaction (RT-qPCR), and Western blot analysis.

RESULTS

Thirty-three components were identified in JGTCs. The serological and histomorphological assays revealed that JGTC treatment reduced levels of blood glucose and lipids, aspartate aminotransferase, alanine aminotransferase, and lipid accumulation in the liver of diabetic rats. According to 16S rDNA sequencing, JGTCs improved species richness and diversity in diabetic rats' intestinal flora and restored 22 dysregulated bacteria to control levels. Fecal metabolomics analysis showed that the altered fecal metabolites were rich in metabolites, such as histidine, taurine, low taurine, tryptophan, glycerophospholipid, and arginine. Serum metabolomics analysis indicated that serum metabolites were enriched in the metabolism of glycerophospholipids, fructose and mannose, galactose, linoleic acid, sphingolipids, histidine, valine, leucine and isoleucine biosynthesis, and tryptophan metabolism. Heatmaps revealed a strong correlation between metabolic parameters and gut microbial phylotypes. Molecular biology assays showed that JGTC treatment reversed the decreased expression of farnesoid X receptor (FXR) in the liver of diabetic rats and inhibited the expression of lipogenic genes (Srebp1c and FAS) as well as inflammation-related genes (interleukin (IL)-β, tumor necrosis factor (TNF)-α, and IL-6). Liver metabolomics analysis indicated that JGTC could significantly regulate a significant number of bile acid metabolites associated with FXR, such as glyco-beta-muricholic acid, glycocholic acid, tauro-beta-muricholic acid, and tauro-gamma-muricholic acid.

CONCLUSIONS

This was the first study to investigate the mechanisms of JGTCs' effects on liver lipid disorders in diabetic rats. JGTCs inhibited liver lipid accumulation and inflammatory responses in diabetic rats by affecting intestinal flora and metabolic disorders and regulating FXR-fat synthesis-related pathways to alleviate diabetic lipid disorders.

FXR overexpression prevents hepatic steatosis through inhibiting AIM2 inflammasome activation in alcoholic liver disease

BACKGROUND AND PURPOSE

Alcoholic liver disease (ALD), a metabolic liver disease caused by excessive alcohol consumption, has attracted increasing attention due to its high prevalence and mortality. Up to date, there is no effective and feasible treatment method for ALD. This study was to investigate whether Farnesoid X receptor (FXR, NR1H4) can alleviate ALD and whether this effect is mediated by inhibiting absent in melanoma 2 (AIM2) inflammasome activation.

METHODS

The difference in FXR expression between normal subjects and ALD patients was analyzed using the Gene Expression Omnibus (GEO) database. Lieber-DeCarli liquid diet with 5% ethanol (v/v) (EtOH) was adopted to establish the mouse ALD model. Liver histopathological changes and the accumulation of lipid droplets were assessed by H&E and Oil Red O staining. Quantitative real-time PCR, Western blotting analysis and immunofluorescence staining were utilized to evaluate the expression levels of related genes and proteins. DCFH-DA staining was adopted to visualize reactive oxidative species (ROS).

RESULTS

FXR was distinctly downregulated in liver tissues of patients with steatosis compared to normal livers using the GEO database, and in ethanol-induced AML-12 cellular steatosis model. FXR overexpression ameliorated hepatic lipid metabolism disorder and steatosis induced by ethanol by inhibiting the expression of genes involved in lipid synthesis and inducing the expression of genes responsible for lipid metabolism. Besides, FXR overexpression inhibited ethanol-induced AIM2 inflammasome activation and alleviated oxidative stress and ROS production during ethanol-induced hepatic steatosis. However, when FXR was knocked down, the results were completely opposite.

CONCLUSIONS

FXR attenuated lipid metabolism disorders and lipid degeneration in alcohol-caused liver injury and alleviated oxidative stress and inflammation by inhibiting AIM2 inflammasome activation.