JiaGaSongTang improves chronic cholestasis via enhancing FXR-mediated bile acid metabolism

Bile acid (BA) enterohepatic circulation disorders are a main feature of chronic cholestatic diseases. Promoting BA metabolism is thus a potential method of improving enterohepatic circulation disorders, and treat enterohepatic inflammation, oxidative stress and fibrosis due to cholestasis.

To investigate the effect of JiaGaSongTang (JGST) and its blood-absorbed ingredient 6-gingerol on α-naphthylisothiocyanate (ANIT)-induced chronic cholestasis, as well as elucidate the underlying regulatory mechanism.

Chronic cholestasis was induced in mice via subcutaneous injection of ANIT (50 mg/kg) every other day for 14 d. Treatment groups were administered JGST orally daily. Damage to the liver and intestine was observed using histopathological techniques. Biochemical techniques were employed to assess total BA (TBA) levels in the serum, liver, and ileum samples. Liquid chromatograph-mass spectrometry/mass spectrometry (LC-MS/MS) was used to analyze fecal BA components. Bioinformatic methods were adopted to screen the core targets and pathways. The blood-absorbed ingredients of JGST were scrutinized via LC-MS/MS. The effects of the major JGST ingredients on farnesoid X receptor (FXR) transactivation were validated using dual luciferase reporter genes. Lastly, the effects of the FXR inhibitor, DY268, on JGST and 6-gingerol pharmacodynamics were observed at the cellular and animal levels.

JGST ameliorated pathological impairments in the liver and intestine, diminishing TBA levels in the serum, liver and gut. Fecal BA profiling revealed that JGST enhanced the excretion of toxic BA constituents, including deoxycholic acid. Bioinformatic analyses indicated that JGST engaged in anti-inflammatory mechanisms, attenuating collagen accumulation, and orchestrating BA metabolism via interactions with FXR and other pertinent targets. LC-MS/MS analysis identified six ingredients absorbed to the bloodstream, including 6-gingerol. Surface plasmon resonance (SPR) and dual luciferase reporter gene assays confirmed the abilities of 6-gingerol to bind to FXR and activate its transactivation. Ultimately, in both cellular and animal models, the therapeutic efficacy of JGST and 6-gingerol in chronic cholestasis was attenuated in the presence of FXR inhibitors.

The findings, for the first time, demonstrated that 6-gingerol, a blood-absorbed ingredient of JGST, can activate FXR to affect BA metabolism, and thereby attenuate ANIT-induced liver and intestinal injury in chronic cholestasis mice model via inhibition of inflammation, oxidative stress, and liver fibrosis, in part in a FXR-dependent mechanism.