Isolation and characterization of uterine leukocytes collected using a uterine swab technique.

PROBLEM: Leukocytes from the maternal-fetal interface are a valuable tool to study local changes in immune function during pregnancy; however, sampling can be challenging due to inadequate tissue availability and the invasive nature of placental bed biopsy. Here, we aim to purify and characterize leukocytes from paired peripheral and uterine blood samples to assess whether a less invasive method of uterine blood collection could yield a population of enriched uterine leukocytes suitable for ex vivo and in vitro analyses. METHOD OF STUDY: Human peripheral blood mononuclear cells (PBMC) and uterine blood mononuclear cells (UBMC) expressed from surgical gauze post C-section were isolated, and immunophenotypic information was acquired by multi-parameter flow cytometry. PBMC and UBMC were stained for markers used to define T and B lymphocytes, macrophages, regulatory T (TReg ) cells, and natural killer (NK) cells. Prime flow was performed to check expression and analysis of CD16- CD56++ and CD16- CD56++ NK transcripts in PBMC and UBMC samples. RESULTS: Immunophenotyping revealed that over 95% of both live PBMC and UBMC consisted of CD45+ leukocytes. Higher percentages of CD16- CD56++ , characterized as uterine NK (uNK) cells, were observed in UBMC samples as compared to PBMC samples (18.41% of CD45+ CD3- vs. 2.73%, respectively), suggesting that CD16- CD56++ cells were enriched in these samples. In UBMC, 49.64% of CD3-negative cells were of peripheral NK phenotype (CD16+ CD56++ ), suggesting infiltration of maternal peripheral NK (pNK) cell in the uterine interface. CONCLUSION: Intrauterine leukocytes, especially CD16- CD56++ NK cells, can be collected in sufficient numbers with increased purity by sampling the uterine cavity postdelivery with surgical gauze. Our results suggest that this non-invasive protocol is a useful sampling technique for isolating CD16- CD56++ cells, however, due to peripheral blood contamination, the NK cell yield could be lower compared to actual decidual or endometrial samples post-partum which is more invasive.

Autoimmune Regulator is required in female mice for optimal embryonic development and implantation†.

Autoimmune Regulator (AIRE) regulates central immune tolerance by inducing expression of tissue-restricted antigens in thymic medullary epithelial cells, thereby ensuring elimination of autoreactive T cells. Aire mutations in humans and targeted Aire deletion in mice result in multiorgan autoimmune disease, known in humans as autoimmune polyglandular syndrome type 1 (APS-1). APS-1 is characterized by the presence of adrenal insufficiency, chronic mucosal candidiasis, and/or hypoparathyroidism. Additionally, females often present with gonadal insufficiency and infertility. Aire-deficiency (KO) in mice results in oophoritis and age-dependent depletion of follicular reserves. Here, we found that while the majority of young 6-week-old Aire-KO females had normal follicular reserves, mating behavior, and ovulation rates, 50% of females experienced embryonic loss between gestation day (GD) 5.5 and 7.5 that could not be attributed to insufficient progesterone production or decidualization. The quality of GD0.5 embryos recovered from Aire KO mice was reduced, and when cultured in vitro, embryos displayed limited developmental capacity in comparison to those recovered from wild-type (WT) mice. Further, embryos flushed from Aire KO dams at GD3.5 were developmentally delayed in comparison to WT controls and had reduced trophoblastic outgrowth in vitro. We conclude that AIRE does not play a direct role in uterine decidualization. Rather, reduced fertility of Aire-deficient females is likely due to multiple factors, including oophoritis, delayed preimplantation development, and compromised implantation. These effects may be explained by autoimmune targeting of the ovary, embryo, or both. Alternatively, altered embryonic development could be due to a direct role for AIRE in early embryogenesis.