It has reported that interleukin-22 (IL-22) promotes the invasion of tumor cells. IL-22 in the endometriotic milieu stimulates the proliferation of human endometrial stromal cells (ESCs). The present study aimed to elucidate whether and how IL-22 regulates the invasion of ESCs from adenomyosis. The expression of IL-22 and its receptors in normal endometrium, eutopic endometrium and ectopic lesion was analyzed by immunohistochemistry; the invasiveness of ESCs in vitro was verified by Matrigel invasion assay; and the effects of IL-22 on the correspondent functional molecules were investigated by ELISA and flow cytometry. Here we found that IL-22 and its receptors IL-22R1 and IL-10R2 in eutopic endometrium and ectopic lesion of adenomyosis were significantly higher than that of normal endometrium. Recombinant human IL-22 (rhIL-22) increased IL-22R1 and IL-10R2 levels on ESCs. Moreover, rhIL-22 promoted the invasiveness of ESCs, and inhibited the expression of metastasis suppressor gene CD82, stimulated the secretion of IL-8, RANTES, IL-6 and VEGF of ESCs. On the contrary, the neutralizing antibody for IL-22 reversed these effects. Our current study has demonstrated that IL-22 has a positive feedback on the expression of its receptors IL-22R1 and IL-10R2 on ESCs. This autocrine effect of IL-22 promotes the invasion of ESCs possibly through regulating invasion-related molecules, suggesting that the abnormal high expression of IL-22 may play an important role in ESCs invasion and finally contribute to the origin and development of adenomyosis.
Keywords: IL-22; adenomyosis; endometrial stromal cells; invasion.