Kotaro Kitaya

IL-15 Expression at Human Endometrium and Decidua

Abstract A large number of natural killer (NK) cells appear in human uterine mucosa during the secretory phase and first trimester pregnancy. We investigated the expression of interleukin (IL)-15, a possible stimulator for these NK cells, in human endometrium and first trimester decidua. Semiquantitative reverse transcriptase-polymerase chain reaction revealed that IL-15 mRNA expression was stronger during the secretory phase and first trimester pregnancy than during the proliferative phase. Immunohistochemistry revealed that immunoreactivity for anti-IL-15 was higher during the secretory phase than it was during the proliferative phase. This was prominent in the perivascular stromal cells around invading spiral arteries during the mid- to late-secretory phase. In first trimester decidua, endothelial cells were also stained as strongly as stromal cells. A membrane-bound IL-15 molecule was detected on the surface of first trimester decidual cells by flow cytometry. Progesterone stimulated the release of soluble IL-15 in the supernatant of cultured decidual cells. These results suggest that IL-15 expression in human uterine mucosa corresponds to the fluctuation of uterine NK cells and that its production is hormonally controlled, especially by progesterone.

Prevalence of chronic endometritis in recurrent miscarriages.

Chronic endometritis was identified immunohistochemically in 9.3% of patients with recurrent miscarriages (in 12.9% of patients with miscarriages of unknown etiology). Chronic endometritis is not negligible in patients with recurrent miscarriages.

Potential Selectin L Ligands Involved in Selective Recruitment of Peripheral Blood CD16(–) Natural Killer Cells into Human Endometrium

Abstract Unique CD16(–) natural killer (NK) cells appear in the human cycling endometrium and acutely increase in number after ovulation. Selective recruitment from peripheral blood (PB) CD16(–) NK cells is a potential mechanism for the postovulatory increase of these NK cells. The interaction between selectin L, an adhesion molecule playing a critical role in leukocyte extravasation, and its ligands may be involved in this phenomenon. We investigated the menstrual cycle-dependent fluctuation of selectin L expression on PB CD16(–) NK cells and selectin L ligand expression in the human endometrial endothelium. The expression of selectin L on PB CD16(–) NK cells was constantly high throughout the menstrual cycle compared with other PB CD16(+) NK cells and non-NK lymphocytes. Among eight selectin L ligands examined, podocalyxin-like, mucosal addressin cell adhesion molecule-1 (MADCAM1) and chondroitin sulfate proteoglycan 2 (CSPG2) were localized in the endometrial endothelium. Semiquantitative score of immunostaining intensity in the endometrial endothelium for MADCAM1 was highest in the late secretory phase, whereas that for CSPG2 peaked throughout the secretory phase. There was a strong positive correlation between the number of endometrial NK cells and the semiquantitative score for CSPG2. Three active isoforms of CSPG2 mRNA were detected in the human endometrium. These findings support the idea that the interaction between selectin L and selectin L ligands functions in the postovulatory selective recruitment of PB CD16(–) NK cells into the human endometrium.

Effect of female sex steroids on human endometrial CD16neg CD56bright natural killer cells

OBJECTIVE To clarify whether female sex steroids directly affect the bioactivity of the human endometrial CD16neg CD56bright natural killer (NK) cells. DESIGN In vitro study. SETTING University obstetrics and gynecology department. PATIENT(S) Thirteen women with histologically normal endometrium who were undergoing hysterectomy and seven women during the first trimester of pregnancy who were undergoing selective termination. INTERVENTION(S) Endometrium or decidua was obtained. MAIN OUTCOME MEASURE(S) The effects of 17beta-estradiol or progesterone (10(-6), 10(-7), and 10(-8) M) on the proliferation, cytolytic activity, and cytokine secretion of the isolated endometrial CD16neg CD56bright NK cells were examined using a 3H-thymidine incorporation assay, 51Cr-releasing assay, and enzyme-linked immunosorbent assay, respectively. RESULT(S) Neither 17beta-estradiol nor progesterone had significant effects on the proliferation, cytolytic activity, and cytokine secretion of endometrial CD16neg CD56bright NK cells. CONCLUSION(S) Female sex steroids do not directly affect the bioactivity of the human endometrial CD16neg CD56bright NK cells.

Immunohistochemistrical and Clinicopathological Characterization of Chronic Endometritis

Citation Kitaya K, Yasuo T. Immunohistochemistrical and clinicopathological characterization of chronic endometritis. Am J Reprod Immunol 2011; 66: 410–415

Aberrant expression of selectin E, CXCL1, and CXCL13 in chronic endometritis

Chronic endometritis is often identified in the patients with unexplained infertility, and is histopathologically characterized by infiltration of plasmacytes within the endometrial stroma. In parallel with stromal plasmacyte infiltration, the endometrial functional layer in chronic endometritis is invaded by B cells, which are a rare leukocyte subset residing within the basal layer in the nonpathological endometrium. In this study, we investigated the molecular expression underlying this unusual increase of B cells in chronic endometritis. Twenty-two out of 76 infertile patients were diagnosed with chronic endometritis from the stromal plasmacyte infiltration, and the endometrium contained numerous stromal B-cell aggregates and glandular single B cells. However, the other major leukocyte subsets, including T cells, natural killer cells, macrophages, and neutrophils were comparable in densities in chronic endometritis and nonpathological endometrium. The microvascular endothelium showed immunoreactivity to adhesion molecule selectin E and chemokine CXCL13 along with immunoreactivity to CXCL1 in the glandular epithelium in chronic endometritis, but not in the nonpathological endometrium. Lipopolysaccharide significantly induced surface selectin E expression and CXCL13 secretion in uterine microvascular endothelial cells, and CXCL1 secretion in endometrial epithelial cells in vitro. These findings indicated that the aberrant local microenvironment triggered possibly by bacterial infection has a role in selective extravasation of circulating B cells in chronic endometritis.

Dermatan sulfate proteoglycan biglycan as a potential selectin L/CD44 ligand involved in selective recruitment of peripheral blood CD16(−) natural killer cells into human endometrium

Unique CD16(−) NK cells acutely increase in the human uterine endometrium after ovulation. The origin of these NK cells remains unknown, but they may be recruited selectively from the circulation. Proteoglycans and their glycosaminoglycan side‐chains expressed on endometrial microvascular endothelial cells play a key role in lymphocyte tethering/rolling, the initial step of lymphocyte extravasation. In this study, we sought for the potential proteoglycans involved in tethering/rolling of peripheral blood CD16(−) NK cells on endometrial microvascular endothelial cells. As compared with CD16(+) NK cells and non‐NK cells, enriched peripheral blood CD16(−) NK cells bound preferably to immobilized glycosaminoglycans except for keratan sulfate. CD16(−) NK cells bound maximally to dermatan sulfate (DS), which was diminished by enzymatic pretreatment with dermatanase and chondroitinase ABC, but not with chondroitinase ACII. The binding capacity of CD16(−) NK cells to DS was attenuated by blocking antibodies against selectin L and CD44 or pretreatment of CD16(−) NK cells with IL‐15. Of three known DS proteoglycans, biglycan and decorin but not epiphycan were expressed in the human cycling endometrium. In the endometrial microvessels, the immunoreactivity for biglycan was greater in the secretory phase than in the proliferative phase, and there was little, if any, immunoreactivity for decorin throughout the menstrual cycle. The ovarian steroid progesterone enhanced biglycan expression in cultured human uterine microvascular endothelial cells. These findings demonstrated that DS proteoglycan biglycan is a potential selectin L/CD44 ligand involved in tethering/rolling of peripheral blood CD16(−) NK cells on endometrial microvascular endothelial cells.

Chronic Endometritis: Potential Cause of Infertility and Obstetric and Neonatal Complications.

Chronic endometritis (CE) is a local inflammatory disease characterized by unusual plasmacyte infiltration in the endometrial stromal areas. CE has been neglected in gynecologic practice, as it is a less symptomatic benign disease that requires demanding and time‐consuming histopathologic examinations for the definite diagnosis. Recent studies, however, suggest the association of CE with infertility and obstetric and neonatal complications. In this review article, we aimed to update the knowledge on epidemiology, etiology, and pathogenesis of CE as well as discuss its clinical management from diagnosis to treatment.

Leukocyte density and composition in human cycling endometrium with uterine fibroids

In this study, we evaluated the leukocyte density and composition in the human cycling endometrium with uterine fibroids (UF). The endometrium with neighboring nodule (NN group, n = 62), autologous endometrium without NN (non-NN group, n = 62), and allogeneic endometrium without UF (non-UF group, n = 24) were immunostained for the leukocyte common and subset-specific antigens. The immunoreactive cells in the unit areas were enumerated under a light microscope. The stromal pan-leukocyte density in the proliferative phase was significantly higher in the endometrium in the NN group than in the non-NN group. The macrophage density was higher in the NN group than in the non-NN group throughout the menstrual cycle. The NK cell density in the mid-to-late secretory phase was lower in the NN group than in the non-NN group. The T cell density in the midsecretory phase was higher in the non-NN group than in the non-UF group. The neutrophil density in the proliferative phase was higher in the non-NN group than in the non-UF group. The leukocyte density and composition in the endometrium with UF are different from those without UF, suggesting their local effects on endometrial leukocyte population.

Local mononuclear cell infiltrates in infertile patients with endometrial macropolyps versus micropolyps

STUDY QUESTION Is the endometrial mononuclear cell population in infertile patients altered in subjects with classical endometrial polyps (macropolyps) versus endometrial micropolyps that are hysteroscopically recognized as small uterine cavity protrusions? SUMMARY ANSWER Macropolypoid endometrium had a low density of pan-leukocytes, pan-T cells and natural killer (NK) cells, whereas micropolypoid endometrium was characterized by high density of B cells and plasmacytes, along with a low density of NK cells. WHAT IS KNOWN ALREADY Endometrial micropolyps co-exist at a high rate with chronic endometritis, which is an unusual plasmacyte infiltration within the endometrial stromal compartment. STUDY DESIGN Prospective cross-sectional study. From July 2009 to June 2011, hysteroscopy was performed for infertile women who had been suspected for endometrial macropolyps and who had repeated in vitro fertilization-embryo transfer failure over three or more cycles. Endometrial biopsy samples were obtained from the patients with macropolyps or micropolyps during the proliferative phase. Of 137 patients assessed, 30 were diagnosed with endometrial macropolyps and 34 were diagnosed with endometrial micropolyps. After the exclusion of the cases with heavy uterine bleeding, potential neoplasms, submucosal uterine fibroids, uterine septa, and/or intrauterine adhesion, 23 patients with macropolypoid endometrium; 25 patients with micropolypoid endometrium and 27 patients with non-polypoid endometrium were enrolled in the study. Endometrial macropolyps were surgically removed, whereas chronic endometritis was treated with antibiotics. The patients were followed up until December 2011. PARTICIPANTS/MATERIALS, SETTING, METHODS The paraformaldehyde-fixed paraffin-embedded endometrial sections were immunostained with monoclonal antibodies against the specific markers of pan-leukocytes (CD45), pan-T cells (CD3), Th cells (CD4), Tc cells (CD8), B cells (CD20), plasmacytes (CD138), NK cells (CD56) and macrophages (CD68). The immunoreactive cells were enumerated in at least 20 non-overlapping stromal areas. MAIN RESULTS AND THE ROLE OF CHANCE Compared with the non-polypoid endometrium, macropolypoid endometrium contained a lower density of pan-leukocytes, pan-T cells and NK cells, whereas micropolypoid endometrium had a higher density of pan-leukocytes and B cells, along with a lower density of NK cells. Following the treatments, 10 patients with macropolypoid endometrium, 11 patients with micropolypoid endometrium and 10 patients with non-polypoid endometrium conceived. LIMITATIONS, REASONS FOR CAUTION One potential bias is immunohistochemical enumeration for leukocyte density was conducted by one examiner. The limitation of this study is that the results relied on endometrial biopsy specimens, of which immunological conditions may not always represent those in the whole endometrium. WIDER IMPLICATIONS OF THE FINDINGS There may be some ethnic or racial variances in the composition of the endometrial mononuclear cell subsets of infertile women. STUDY FUNDING/COMPETING INTEREST(S) This study was supported by Grand-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (22591840). There were no conflicts of interest to declare.