Hitomi Chiba

NK22 Cells in the Uterine Mid-Secretory Endometrium and Peripheral Blood of Women with Recurrent Pregnancy Loss and Unexplained Infertility

We aimed to investigate natural killer 22 (NK22) cells in the peripheral blood and the uterine endometrium of women with unexplained recurrent pregnancy loss (URPL) and unexplained infertility (UI).

Expression of Natural Cytotoxicity Receptors on and Intracellular Cytokine Production by NK Cells in Women with Gestational Diabetes Mellitus.

To determine the role of peripheral blood NK (pNK) cells in putative etiology of gestational diabetes, the expression of surface markers on pNK cells and the percentage of cytokine‐producing pNK cells in women at 12 weeks of pregnancy with gestational diabetes mellitus (GDM) were studied.

Expression of retinoid‐related orphan receptor (ROR)γt on NK22 cells in the peripheral blood and uterine endometrium of women with unexplained recurrent pregnancy loss and unexplained infertility

Recently, NK22 cells, a subset of interleukin (IL)‐22‐producing natural killer (NK) cells, were identified. We have previously reported the higher percentage of NK22 cells in women suffering recurrent pregnancy loss (RPL). Moreover, we have also reported lower expression of NKp46, a kind of natural cytotoxicity receptor (NCR), on NK cells and the changes of NK cell producing cytokines in women who experience RPL. NK22 cells express NCRs, such as NKp44 or NKp46. Retinoid‐related orphan receptor γt (RORγt) is known as a regulator of NK22 cells; however, in NK22 cells of peripheral blood (PB) and the uterine endometrium (UE), the relationship between NCRs and RORγt is unclear. We investigate RORγt expression NK22 cells in the PB and UE of women with unexplained infertility (uI) or unexplained RPL (uRPL).

NK cell abnormality and its treatment in women with reproductive failures such as recurrent pregnancy loss, implantation failures, preeclampsia, and pelvic endometriosis

The regulation of uterine and peripheral blood natural killer (NK) cells has been associated with problems related to reproductive immunology such as recurrent pregnancy loss (RPL), implantation failure or preeclampsia. NKp46, one of the natural cytotoxicity receptors (NCRs), is a unique marker that functions in NK cell cytotoxicity and cytokine production. Expression of NKp46 on NK cells is lower in women with recurrent pregnancy loss and pregnancy-induced hypertension. Moreover, expression of NKp46 on peritoneal fluid NK cells is lower in women with pelvic endometriosis. Therefore, evaluation of NKp46 on peripheral blood NK cells may provide a means of screening for reproductive abnormalities. Recently, a new type of NK cell, the NK22 cell, has been reported. This cell may be a regulator not only of the mucosal barrier but also of reproduction.For women with RPL showing abnormal uterine and/or peripheral blood NK cells, both intravenous immunoglobulin treatment and intralipid treatment have been reported. The effects of these treatments are still controversial, and further studies are needed in order to clarify their true impact. The present review examines variations in the expression of NCRs on NK cells, the participation of NK22 cells in reproduction, and the possible use of intravenous immunoglobulin or intralipid treatment for women with recurrent pregnancy loss and NK cell abnormality.

A case of bilateral tubal pregnancy

Bilateral tubal pregnancy is very rare and occurs in only 1 out of every 200,000 spontaneous pregnancies. In this case, a 29-year-old woman with a history of primary infertility underwent treatment with human menopausal gonadotropin (hMG)-human chorionic gonadotropin (hCG), and became pregnant. A gestational sac (GS) was not detected in the uterus and transvaginal ultrasonography (USG) revealed GS with fetal heartbeat in the left adnexa at 7 weeks and 6 days of gestation. The patient underwent laparoscopic surgery and ultimately, bilateral tubal pregnancy was diagnosed. Consequently, bilateral fallopian tube resection was performed. Afterwards, she conceived by assisted reproductive technology (ART) and delivered vaginally. This case suggests that even if a GS is found in one fallopian tube by USG, it is important to evaluate the other fallopian tube carefully. Abbreviations: TV-USG, transvaginal ultrasound; hCG, human chorionic gonadotropin; DD, dichorionic-diamniotic.