Desmodium styracifolium (Osb.) Merr. Extracts alleviate cholestatic liver disease by FXR pathway

Cholestatic liver disease (CLD) is a disease characterized by cholestasis. Farnesoid X receptor (FXR) is a nuclear receptor that maintains homeostasis in bile acid metabolism. Studies have shown that gut microbiota interfered with the FXR pathway. Modulation of FXR to inhibit cholestasis has become a key measure in the treatment of CLD. In traditional folk medicine, Desmodium styracifolium (Osb.) Merr. was used as a primary treatment for gallstones, gonorrhea, jaundice, cholecystitis and other diseases. Modern pharmacological studies had also found that the herb has anti-calculus, anti-inflammatory, antioxidant, diuretic and liver damage. Therefore, we speculated that Desmodium styracifolium (Osb.) Merr. extracts (DME) could alleviate CLD through the FXR pathway and might be associated with the gut microbiota. However, studies of DME alleviating CLD through the FXR pathway have not been reported.

To study the effect and mechanism of DME in relieving CLD through in vivo and in vitro experiments.

First, mice were administrated with alpha-naphthyl isothiocyanate (ANIT) to establish a CLD model in vivo. Meanwhile, HepG2 cells were induced by lithocholic acid (LCA) to establish the CLD model in vitro. To evaluate the therapeutic effect of DME on CLD mice, hematoxylin-eosin (HE) staining, and biochemical indicators were performed. The prototype of the blood components in mice serum was detected by ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). 16S rDNA sequencing was used to analyze the gut microbiota. Finally, the protein and mRNA expression of the FXR pathway in mice liver tissues or HepG2 cells were detected by Western blot, qRT-PCR, or immunofluorescence.

Pathological testing and biochemical indexes showed that DME significantly reduced serum ALT, AST, ALP, TBIL, DBIL, TBA and liver TBA levels, and attenuated liver tissue injury, necrosis and jaundice in CLD mice. In addition, MetagenomeSeq analysis of gut microbiota showed that DME significantly up-regulated the abundance of Parvibacter, down-regulated the abundance of Paenalcaligenes, and regulated bile acid homeostasis. In terms of mRNA expression, DME significantly upregulated the mRNA levels of Nr1h4, Abcb11, Cyp7a1 and Slc10a1. Meanwhile, in terms of protein expression, DME significantly up-regulated the protein expression levels of FXR, BSEP, CYP7A1 and NTCP, which regulated bile acid homeostasis. Finally, the molecular docking results showed that the components of DME, such as Lumichrome, Daidzein and Folic acid, all had good binding ability with FXR, and the surface plasmon resonance (SPR) results also showed that both Lumichrome and Daidzein had a relatively high affinity with FXR.

DME alleviated CLD through the FXR pathway, and the mechanisms might be associated with the gut microbiota.