Ethyl acetate extract from Herpetospermun cardigerum wall. Ameliorated concanavalin A-induced autoimmune hepatitis in mice by reprofiling gut microenvironment to modulate IDO1/KYN and PI3K/AKT/NF-κB pathways

Abstract

Background

Autoimmune hepatitis (AIH) is an immunoinflammatory chronic liver disease with increasing prevalence worldwidely, lacking of effective medicine. Herpetospermum caudigerum Wall. (HC) is a traditional Tibetan medicine used to treat liver diseases for thousands of years. However, investigation into the effects of HC in AIH remains scarce.

Purpose

Our study aimed to explore the effects and mechanisms of ethyl acetate extract from the seeds of HC (HCDEAE) against concanavalin A (Con A)-induced liver impairment in mouse.

Study design and methods

HCDEAE was extracted from the seeds of HC, then characterized by UPLC-Q-TOF/MS. Con A-induced AIH mice were used to investigate the impacts of HCDEAE on liver impairment, T cells differentiation, gut microbiota and its derived metabolites, intestinal barrier impairment and inflammation, as well as the mechanisms of HCDEAE in liver in AIH.

Results

HCDEAE (90 mg/kg, i.g.) effectively alleviated Con A-induced hepatic pathological damage, suppressed elevation of serum ALT, AST, IFN-γ, and TNF-α; in spleen, HCDEAE attenuated spleen impairment, elevated the percentage of CD4⁺CD25⁺ cells and FOXP3 gene expression, inhibited up-regulation of RORγt gene expression and IL-17; in liver, HCDEAE down-regulated IL-17, elevated FOXP3 gene expression and IL-10, increased the protein and gene expression of TGF-β1; in colon, HCDEAE attenuated intestinal barrier impairment, inhibited down-regulation of Occludin and ZO-1, and relieved elevation of IL-1β, as well as re-profiled the gut microenvironment. Furthermore, HCDEAE demonstrated the ability to elevate tryptophan metabolism among kynurenine pathway, activate IDO1/KYN pathway and inhibit PI3K/AKT/NF-κB signaling pathway in liver of AIH mice.

Conclusion

Pretreatment with HCDEAE (90 mg/kg·d⁻¹, i.g.) for 9 days could effectively alleviate the liver inflammation and injure, protect intestinal barriers, attenuate spleen impairment, maintain Treg-Th17 cell equilibrium in Con A-induced AIH mice, via re-profiling gut microbiota, modulation of tryptophan metabolism in the gastrointestinal tract and in liver, to activate IDO1/KYN pathway and inhibit the abnormal activation of PI3K/AKT/NF-κB signaling pathway in liver. The present study highlighted the potential of HCDEAE as a drug candidate for AIH.