FuKe QianJin Capsule alleviates endometritis via inhibiting inflammation and pyroptosis through modulating TLR4/ NF-κB /NLRP3 pathway

Ethnopharmacological relevance: Fuke Qianjin Capsule (FKC), a traditional Chinese medicine commonly employed for treating endometritis, lacks reported treatment mechanisms.

Aim of the study: The aim of the present study was to explore the role and mechanism of FKC in lipopolysaccharide (LPS)-induced endometritis.

Materials and methods: The main active ingredients of FKC were identified via high-performance liquid chromatography (HPLC) in conjunction with standard substances. Prior to endometritis induction, Sprague Dawley female rats received FKC for 7 days. The endometritis model was established through an intrauterine injection of 1 mg/kg LPS. Concurrently, an LPS-induced RAW264.7 cell inflammation model was utilized, in which the cells were treated with serum containing Fuke Qianjin Capsule. Pathological alterations in the endometrium were assessed via H&E staining and transmission electron microscopy (TEM). The contents of MPO in uterine tissues, and NO release in cells, along with the secretion of IL-18, IL-1β, IL-6, and TNF-α in both tissues and cells, were determined via assay kits. The mRNA levels of Nlrp3, Caspase-1, Gsdmd, and Il-1β in uterine tissues and cells were analyzed via qPCR. The protein levels of TLR4, p65, p-P65, NLRP3, Caspase-1, GSDMD, and IL-1β in these samples were evaluated through Western blot analysis. Immunofluorescence was used to assess the protein levels of p-P65 and NLRP3 in uterine tissues and cells.

Results: Five primary active components of FKC were identified. Treatment with FKC in vivo mitigated endometrial pathological damage and significantly decreased the levels of MPO, IL-18, IL-1β, IL-6, and TNF-α, as well as the levels of Nlrp3, Caspase-1, Gsdmd, and Il-1β mRNA in tissue samples. Treatment with FKC inhibited the expression of TLR4, p-P65, NLRP3, Caspase-1, GSDMD, and IL-1β, as well as reduced NLRP3 protein fluorescence intensity, and inhibited P65 phosphorylation. In vitro findings demonstrated that FKC-containing serum reduced IL-18, IL-1β, IL-6, and TNF-α levels, as well as reduced Nlrp3, Caspase-1, Gsdmd, and Il-1β mRNA levels. In addition, FKC-containing serum inhibited the protein expression of TLR4, p-P65, NLRP3, Caspase-1, GSDMD, and IL-1β. FKC-containing serum also reduced NLRP3 protein fluorescence intensity and suppressed P65 phosphorylation.

Conclusion: FKC reverses the LPS induced NLRP3 inflammasome activation, and mitigates inflammation and pyroptosis through the modulation of the TLR4/NF-κB/NLRP3 pathway, thereby alleviating endometritis.