Involvement of natural killer cells in the pathogenesis of endometriosis in patients with pelvic pain

OBJECTIVES: To detect the involvement of immune cells in the pathogenesis of endometriosis in patients with stable status or pelvic pain. METHODS: Blood was collected from patients with endometriosis with and without pelvic pain. Natural killer (NK) and Th17 cells were analyzed by flow cytometry, and secretion of inflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-1β, IL-6, IL-7) was verified by enzyme-linked immunosorbent assay. We isolated immune cells from blood by density-gradient centrifugation to investigate the expression of functional molecules including sterile alpha motif domain-containing protein 9 (SAMD9), Ral guanine nucleotide dissociation stimulator-like 2 (RGL2), early growth response protein 1, and Akirin2. We also searched the BIOGPS database for protein expression profiles. RESULTS: SAMD9 and RGL2 expression levels were significantly upregulated in patients with pelvic pain. Furthermore, lysophosphatidic acid receptor 1 expression was higher in endometrial tissues from patients with pelvic pain, and was mainly localized in stromal and glandular epithelial cells in ectopic lesions. CONCLUSION: NK cells play an important role in the pathogenesis of endometriosis in patients with pelvic pain. Suppressing the cytotoxic activity of NK cells may thus help to reduce the progression of pelvic pain in patients with endometriosis.