CHS-Ⅳa activates the IGF1R/PI3K signal pathway with inhibited pyroptosis of endometrial stromal cells and progress of endometriosis

Ethnopharmacological relevance: Chikusetsusaponin IVa (CHS IVa) as a natural extract from the Panax japonicus (T.Nees) C.A.Mey (P. japonicus), can regulate the immune responses, such as anti-inflammation, which have been applied in treating various diseases. It is still unclear, nevertheless, whether the CHS IVa can target-able treat endometriosis (EMs) and what the possible mechanism would be.

Purpose of the study: This work aims to investigate the possible mechanism and the impact of CHS IVa on EMs.

Materials and methods: The EMs models were established in mice by autologous transplantation or chemicals (lipopolysaccharide and adenosine triphosphate), inducing the pyroptotic endometrial stromal cells. Then the CHS IVa was used to treat the EMs mice. The therapeutic impact of CHS IVa was assessed by hematoxylin-eosin staining, immunofluorescent staining, western blot (WB), and enzyme-linked immunosorbent assay (ELISA).

Results: The results of immunofluorescence and WB indicated that pyroptosis indicators, including Gasdermin-D (GSDMD), Caspase-1, NOD-like receptor thermal protein domain associated protein 3 (NLRP3), and interleukin (IL)-1β, were substantially expressed in the ectopic endometrial lesions of EMs mice. The ELISA results showed that the abdominal cavity of EMs mice had higher concentrations of IL-1β, IL-6, and TNF-α than the non-EMs animals (control group). As shown in the molecule docking experiments, CHS IVa exhibited high binding affinity with GSDMD, IL-1β, Caspase-1, and NLRP3. Moreover, after treatment with CHS IVa, the expression levels of GSDMD, IL-1β, Caspase-1, and NLRP3 decreased in the EMs mice. Meanwhile, the expression level of pain-related proteins, such as pro-nerve growth factor (pro-NGF) and transient receptor potential vanilloid-1 (TRPV1), was inhibited via the treatment of CHS IVa. According to the antibody chip analysis, the insulin-like growth factor 1 receptor/phosphatidylinositide 3-kinases (IGF1R/PI3K) signal pathway was essential to the CHS IVa's treatment of EMs. Finally, according to the WB experiments, after the treatment with CHS-Ⅳa, the expression of IGF1R, PI3K, and related phosphorylated proteins increased compared to the mice in lipopolysaccharide + adenosine triphosphate (LPS + ATP) groups.

Conclusion: CHS IVa can activate the IGF1R/PI3K signal pathway, inhibit the pyroptosis of endometrial stromal cells, and relieve the inflammation and EMs.