Taraxasterol extracted from Ixeridium gramineum (Fisch.) Tzvel. Attenuated D-GalN/LPS-induced fulminant hepatitis by modulating the JAK/STAT and TNF signalling pathways

Ethnopharmacological relevance: Taraxasterol (TAR), a compound highly abundant and easily obtainable from Tibetan medicine Ixeridium gramineum (Fisch.) Tzvel., exhibits a variety of biological effects, including hepatoprotective, anti-inflammatory, and antioxidant activities.

Aim of the study: To investigated the protective role and underlying mechanisms of TAR in fulminant hepatitis (FH) through the regulation of oxidative stress, inflammatory responses, and apoptosis by modulating the JAK/STAT and TNF signalling pathways.

Material and methods: The study used Kunming mice to establish a D-GalN/LPS-induced FH model, which was divided into the following groups: Control group, D-GalN/LPS group, D-GalN/LPS + Silymarin group, D-GalN/LPS + TAR 2.5 group, D-GalN/LPS + TAR 5 group, D-GalN/LPS + TAR 10 group, and TAR 10 group. H&E staining and biochemical analyses were employed to evaluate liver pathological changes. Oxidative stress factors and inflammatory response were assessed via ELISA. RNA sequencing analysis was used to detect changes in inflammatory factor genes and apoptosis genes with TAR intervention in liver tissues. The distribution of the proteins p-STAT3 and p-JNK in liver tissues was ascertained using immunohistochemical staining. In vitro experiments were conducted on RAW264.7 cells exposed to LPS and TAR. Apoptosis was evaluated via flow cytometry and Hoechst 33258 staining. Immunofluorescence staining was employed to determine the protein expression levels of p-STAT3 and p-JNK in RAW264.7 cells. Gene and protein expression in the JAK/STAT and TNF signalling pathways, as well as apoptosis, were analyzed using qRT-PCR and Western blotting.

Results: TAR effectively reduced hepatocyte necrosis, diminished inflammatory factor release, inhibited oxidative stress, significantly decreased the apoptosis of RAW264.7 cells, inhibited the protein expressions of p-JAK2, p-STAT3, p-MEK4, p-JNK, Caspase-3, Caspase-8, and Bax, and increased the protein expressions of SOCS3 and Bcl-2.

Conclusion: TAR prevents D-GalN/LPS-induced FH by regulating the JAK/STAT and TNF signalling pathways and apoptosis, demonstrating its therapeutic potential in treating liver diseases.