Exogenous activated NK cells enhance trafficking of endogenous NK cells to endometriotic lesions

Background: Endometriosis is defined as the presence of endometrial glands and stroma at ectopic locations. Although the prevalence of endometriosis is as high as 35 %-50 %, its pathogenesis remains controversial. An increasing number of studies suggest that changes in immune reactivity may be primarily involved in the development of endometriosis development. In this sense, it has been strongly suggested that a fundamental part of immunologic system, the natural killer cells (NK cells), are an important part of this process. NK cells, a component of the innate immune system, have been extensively studied for their ability to defend the organism against infections and malignancy. Recent studies have shown that IL-2-activated NK (A-NK) cells are able to attack and destroy tumors in lungs and livers of mice, demonstrating the therapeutic potential of these cells. Similarly to metastatic tumor cells, endometrial cells are able to adhere, infiltrate and proliferate at ectopic locations. Therefore, in this study, we evaluated the ability of adoptively transferred and endogenous NK cells to infiltrate endometriosis lesions. Methods: As NK cells donors were used C57BL/6 B6. PL-Thy 1.1 female mice. As uterine horns donors were used C57/BL6 +GFP female mice and as endometriosis recipients C57BL/6 Thy1.2 female mice. Endometriosis induction was made by injection of endometrial tissue fragments. After 4 weeks, necessary for endometriosis lesions establishment the animals were divided in 3 experimental groups with 10 animals each. Group 1 received i.v doses of 5x106 A-NK in 200 mu l RPMI; Group 2 received i.p dose of 5x106 A-NK in 200 mu l RPMI and Group 3 received i.p dose of IL2 (0.5 mL RPMI containing 5.000U of IL2). Results: Our data show that exogenous A-NK cells injected via ip combined with endogenous A-NK cells seems to be the most efficient way for activated NK cells track and infiltrate endometriosis. Conclusion: For the first time, it was shown that both endogenous as exogenous A-NK cells are able to track, migrate and infiltrate endometriosis lesion. This seems to be a promising result, and if confirmed the efficiency of A-NK cells in killing endometriosis lesions, maybe in the future we could use this approach as an alternative treatment for women with endometriosis.