[Anti-endometritis effect of carbonized Scutellariae Radix in mice induced by LPS via inhibiting cell pyroptosis through IKBKE/NLRP3 signaling axis]

Abstract

This paper investigated the inhibitory effect of carbonized Scutellariae Radix(Cb-SR) on pyroptosis in endometrial epithelial cells of mice with endometritis and its correlation with the IKBKE/NLRP3 signaling axis. Mice model of endometritis was established by using an intrauterine injection of 10 μL polysaccharides(LPS, 5 mg·mL~(-1)), and the mice were randomly divided into model group(LPS), low-dose group of Cb-SR(L-Cb-SR, 0.55 g·kg~(-1)), medium-dose group of Cb-SR(M-Cb-SR, 1.10 g·kg~(-1)), high-dose group of Cb-SR(H-Cb-SR, 2.20 g·kg~(-1)), crude Scutellariae Radix group(Cr-SR, 1.63 g·kg~(-1)), and Fuke Qianjin Capsule group(FQC, 0.30 g·kg~(-1)), with 10 mice in each group. Ten healthy female mice were selected and injected with PBS of equal volume into the bilateral uterus, and they were set as the sham group. The mice in the drug treatment groups were given the corresponding doses of Cb-SR, Cr-SR, FQC, or physiological saline of equal volume by gavage twice a day for seven days. Thirty minutes after the last administration, each mouse was euthanized by cervical dislocation. Hematoxylin-eosin(HE) staining and transmission electron microscopy were applied to observe the histopathological morphology of the uterine tissue. Immunohistochemistry was used to detect the expression of CD38 and CD138. Myeloperoxidase(MPO) values in neutrophils were measured by the kit; Enzyme-linked immunosorbent assay(ELISA) was used to measure the secretion of interleukin-18(IL-18), interleukin-1β(IL-1β), and tumor necrosis factor-α(TNF-α). Immunofluorescence and Western blot were used to analyze the expression of the proteins related to the IKBKE/NLRP3 signaling axis. Mouse endometrial epithelial cells(MEECs) were separated and purified from the uterine tissue of pregnant female mice through in vitro experiments and injured by LPS for 24 h, and then they were cultured with Cb-SR-containing serum. The anti-endometritis effect of Cb-SR was investigated by CCK-8 assay, scanning electron microscopy, and Western blot. The results showed that Cb-SR significantly reduced MPO values, attenuated uterine tissue damage, inhibited the expression of CD38 and CD138, decreased the levels of IL-1β, IL-18, and TNF-α, and inhibited the expression of proteins associated with IKBKE/NLRP3 signaling axis in mice with endometritis. In addition, Cb-SR-containing serum reduced swelling of MEECs organelles induced by LPS, decreased the expression of inflammatory factors, and suppressed the expression of IKBKE/NLRP3 signaling axis-related proteins. These results suggest that Cb-SR can inhibit endometrial epithelial cell pyroptosis in endometritis by suppressing the IKBKE/NLRP3 signaling axis.

Keywords: IKBKE/NLRP3 signaling axis; carbonized Scutellariae Radix; endometritis; pyroptosis.