Oil‐based contrast for hysterosalpingography‐regulated Th1/Th2‐type cytokines and alleviated inflammation in rats with LPS‐induced chronic endometritis

Abstract Aim The chronic endometritis (CE) prevalence in people experiencing infertility is 2.8–56.8%, pregnancy rates in patients with infertility increase after hysterosalpingography with oil‐based contrast, but the effect and mechanism are not clear. Here, we analyzed the effects of intrauterine ethiodized poppyseed oil (EPO) bathing on a rat model of CE and the possible underlying mechanism. Methods CE rats were induced by lipopolysaccharide (LPS) exposure, and rats were subjected to intrauterine bathing with EPO or phosphate‐buffered saline (PBS) after model verification. Serum and uterus levels of IFN‐γ, IL‐4, TNF‐α, and IL‐1β were detected by ELISA kit, and the number of CD138 + and CD68 + cells and uterine IFN‐γ, IL‐4, TNF‐α, IL‐1β, and NF‐κB P65 expression were detected by immunohistochemistry after bathing. Results LPS exposure induced the typical CE phenotype with CD138 + phagocyte infiltration of the endometrial stroma. Compared with PBS bathing, bathing with EPO in CE rats showed decreases in the CD138 + and CD68 + cells populations and significant decreases in serum and uterine IFN‐γ levels, moreover, uterine IL‐4 levels were slightly higher, and the IFN‐γ/IL‐4(Th1/Th2‐type cytokine ratio) in the uterus was significantly lower. Local IFN‐γ, TNF‐α, and NF‐κB P65 expression in the endometrium was significantly downregulated, while IL‐4 expression was upregulated. Conclusion Intrauterine oil‐based contrast bathing significantly alleviated local inflammation in the rat CE model by downregulating NF‐κB P65 expression, reducing IFN–γ (Th1), increasing IL‐4 levels (Th2) in the endometrium, and regulating the Th1/Th2‐type cytokine trends toward Th2.