The role of cytokines in endometriosis

Problem: To review the literature on the role of peritoneal cytokines in the pathogenesis and endometriosis-related infertility. Methods of study: A MEDLINE search was conducted by the key words of cytokine and endometriosis in the English publications, and references identified within the identified papers were also reviewed. Results: Several cytokines including interleukin (IL)-l, 6, 8, 10, tumor necrosis factor (TNF)-α, and vascular endothelial growth factor (VEGF) were reported to be increased in the peritoneal fluid (PF) of women with endometriosis. Those cytokines may be involved in macrophage activation, inflammatory change and enhanced angiogenesis. However, some cytokines were less expressed such as IL-2, and interferon (IFN)-γ. They reflect the impaired T- and natural killer (NK)-cell function. Endometriotic implants produce some factors, e.g. matrix metalloproteinases (MMPs), Bcl-2, and affect their capacity to implant into the peritoneum. Conclusion: Peritoneal cytokines, which are produced by mesothelial cells, leukocytes and ectopic endometrial cells, interwork locally and systemically in women with endometriosis. More studies about the specific role and interactions of these cytokines are needed to improve the understanding of endometriosis and to develop novel therapies.