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Chronic endometritis (CE) is a type of chronic inflammation in the endometrium that is associated with infertility, which is primarily due to implantation failure. Antibiotics are the most common treatment for CE. However, some patients with CE are resistant to antibiotic treatment, while others refuse this treatment. Therefore, we focused on lactoferrin (Lf), which exhibits antimicrobial and anti-inflammatory properties, and studied its effect on inflammation in endometrial stromal cells (ESCs) from patients with CE. Endometrial tissue was collected from patients with CE, and ESCs were isolated and cultured. When ESCs were cultured with bovine lactoferrin (bLf: 1 mg/mL), the mRNA expression of TNF-α (p < 0.05) and IL-1β (p < 0.01) was significantly decreased compared with that in cells cultured without bLf. The level of TNF-α protein in the culture medium was significantly decreased (p < 0.01), while that of IL-1β was also decreased, but not significantly (p < 0.10), when 1 mg/mL of bLf was added to the culture medium. When more inflammation was induced artificially by adding 0.1 ng/mL of TNF-αto ESCs, the addition of bLf (1 mg/mL) to ESCs decreased IL-6 and IL-1β mRNA expression to levels similar to those in ESCs without TNF-α treatment. Furthermore, it was revealed that the actions of bLf are mediated by the AKT and MAPK intracellular signaling pathways, which are mechanisms by which the increase in TNF-α-induced cytokine expression is suppressed in ESCs. bLf suppresses the expression of inflammatory cytokines in human ESCs and may be a new therapeutic candidate for CE., Competing Interests: Declaration of Competing Interest None of the authors has any conflict of interest related to this manuscript., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Chronic inflammation in cesarean scar defect contributes to secondary infertility in women with cesarean scar syndrom; however, it remains unclear about the situation of inflammation in uterine cavity in women with cesarean scar syndrome. This ambidirectional cohort study aimed to explore the effect of inflammation in the uterine cavities of women with cesarean scar syndrome on infertility at a single university hospital. The frequency of chronic endometritis in infertile patients was retrospectively compared between the cesarean scar syndrome group and non-cesarean scar syndrome group. The frequency of endometriosis was also investigated in patients with cesarean scar syndrome who underwent laparoscopy. The level of tumor necrosis factor-α and interleukin-1β in the uterine cavity was prospectively evaluated in the cesarean scar syndrome group and in women with a history of cesarean section (control group) using an enzyme-linked immunosorbent assay. There was a significant difference in the incidence of chronic endometritis between the cesarean scar syndrome and non-cesarean scar syndrome groups (65.8% and 46.0%, respectively, p = 0.0315). Endometriosis was detected in 51 (70%) patients with laparoscopy. Tumor necrosis factor-α and interleukin-1β levels in the cesarean scar syndrome group were significantly higher than those in the control group (p = 0.0002 and p = 0.0217, respectively). Our findings suggest that one cause of secondary infertility in women with cesarean scar syndrome is embryo implantation failure-associated chronic endometritis, endometriosis, and chronic inflammation in the uterine cavity.

Background: The purpose of the present study was to evaluate the relationship between chronic endometritis and the epithelial-mesenchymal transition in the endometrium of infertile patients in the implantation phase., Methods: Endometrial biopsy specimens from 66 infertility patients were analyzed. The presence of chronic endometritis was investigated by immunostaining for CD138. Immunohistochemical staining for E-cadherin, N-cadherin, Slug, and Snail was performed, and the expression profiles were statistically analyzed according to the presence of chronic endometritis. When the loss of E-cadherin expression and/or the positive expression of N-cadherin was detected, the specimen was considered epithelial-mesenchymal transition-positive. Epithelial-mesenchymal transition-positive cases were also statistically analyzed according to the presence of chronic endometritis. The characteristics of the patients in the epithelial-mesenchymal transition-positive and epithelial-mesenchymal transition-negative groups were compared. The association between variables, including age, body mass index, gravidity, parity, and each causative factor of infertility and epithelial-mesenchymal transition positivity was analyzed., Results: The rates of the loss of E-cadherin expression, the gain of N-cadherin and epithelial-mesenchymal transition positivity were significantly higher in chronic endometritis patients. The expression of Slug, cytoplasmic Snail, and nuclear Snail was also detected at significantly higher rates in chronic endometritis patients. Chronic endometritis were related to the epithelial-mesenchymal transition., Conclusion: The epithelial-mesenchymal transition was frequently detected in the endometrium in infertile patients with chronic endometritis. Since the epithelial-mesenchymal transition is associated with chronic endometritis, the epithelial-mesenchymal transition appears to be involved in the alteration of mechanisms of implantation., Competing Interests: The authors have declared that no competing interests exist.

Background: The diagnostic criteria of chronic endometritis remain controversial in the treatment for infertile patients., Methods: A prospective observational study was conducted in a single university from June 2014 to September 2017. Patients who underwent single frozen-thawed blastocyst transfer with a hormone replacement cycle after histological examination for the presence of chronic endometritis were enrolled. Four criteria were used to define chronic endometritis according to the number of plasma cells in the same group of patients: 1 or more (≥ 1) plasma cells, 2 or more (≥ 2), 3 or more (≥ 3), or 5 or more (≥ 5) in 10 high-power fields. Pregnancy rates, live birth rates, and miscarriage rates of the non-chronic endometritis and the chronic endometritis groups defined with each criterion were calculated. A logistic regression analysis was performed for live births using eight explanatory variables (seven infertility factors and chronic endometritis). A receiver operating characteristic curve was drawn and the optimal cut-off value was calculated., Results: A total of 69 patients were registered and 53 patients were finally analyzed after exclusion. When the diagnostic criterion was designated as the presence of ≥ 1 plasma cell in the endometrial stroma per 10 high-power fields, the pregnancy rate, live birth rate, and miscarriage rate were 63.0% vs. 30.8%, 51.9% vs. 7.7%, and 17.7% vs. 75% in the non-chronic and chronic endometritis groups, respectively. This criterion resulted in the highest pregnancy and live birth rates among the non-chronic endometritis and the smallest P values for the pregnancy rates, live birth rates, and miscarriage rates between the non-chronic and chronic endometritis groups. In the logistic regression analysis, chronic endometritis was an explanatory variable negatively affecting the objective variable of live birth only when chronic endometritis was diagnosed with ≥ 1 or ≥ 2 plasma cells per 10 high-power fields. The optimal cut-off value was obtained when one or more plasma cells were found in 10 high-power fields (sensitivity 87.5%, specificity 64.9%)., Conclusions: Chronic endometritis should be diagnosed as the presence of ≥ 1 plasma cells in 10 high-power fields. According to this diagnostic criterion, chronic endometritis adversely affected the pregnancy rate and the live birth rate.

Problem: The effect of chronic endometritis (CE) on the subpopulation of CD4 + T cells, Th1, Th2, Th17, and regulatory T cells in the endometrium is unknown., Method of Study: Lymphocytes were isolated from the endometrium of CE patients (n = 12) and non-CE patients (n = 7). The CD4 + T-cell profile was analyzed by flow cytometry and immunofluorescence., Results: In the endometrium of CE patients, there were significantly more Th1 cells among CD4 + cells and fewer Th2 cells in comparison to non-CE patients. No marked difference was observed in Th17 cells or Foxp3 + Treg cells. Moreover, the proportion of Th1 cells increased and the proportion of Th2 cells decreased as the number of CD138 + cells increased. Furthermore, when the localization of CD138 + cells and CD4 + cells was examined, CD4 + cells were found to be clustered around CD138 + cells in CE patients., Conclusion: The CD4 + T-cell profile in the endometrium is altered in women with CE. This finding may help to clarify the pathophysiology and development of treatment methods for CE., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Problem: Chronic endometritis (CE) influences the clinical outcomes of assisted reproductive technology. However, the effect of CE on the pregnancy outcome is still unknown., Method of Study: A retrospective case-control study was conducted in a single university. Subjects who conceived by in vitro fertilization within a year after a histological diagnosis of CE under 40 years of age from September 2013 to December 2017 were extracted. The rates of miscarriage, preterm birth, term birth, and live birth per pregnancy according to the presence or absence of CE were analyzed. A logistic regression analysis was performed for miscarriage, preterm birth, term birth, and live birth for eight explanatory variables of seven infertility factors and CE., Results: A total of 39 pregnancies in 38 subjects with non-CE and 35 pregnancies in 32 subjects with CE were ultimately analyzed. The rates of miscarriage, preterm birth, term birth, and live birth per pregnancy were 12.8% and 40.0% (P < .03), 2.6% and 14.3% (P = .1), 84.6% and 45.7% (P < .001) and 84.6% and 57.1% (P < .03) in the Non-CE and CE groups, respectively, although only the analysis for tem birth rate had sufficient power to exclude Type II error. In logistic analysis, CE was a factor affecting the objective variables of miscarriage, term birth, and live birth., Conclusions: The term birth rate among pregnancies decreased mainly due to an increase in miscarriages when CE was detected before pregnancy in patients treated with in vitro fertilization. A histopathological diagnosis of CE adversely affected the term birth rate per pregnancy., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: The presence of chronic deciduitis (CD) was determined in patients diagnosed with or without chronic endometritis (CE) before pregnancy., Objective: To study the effect of CE on decidua in cases of miscarriage., Methods: Decidual tissue was obtained from the patients who miscarried at the first pregnancy within a year after the diagnosis of the presence or absence of CE. The number and distribution pattern of plasma cells stained with CD138 in decidual tissue in 10 high-power fields (HPFs) was examined. The prevalence of CD diagnosed with four different grade; grade 0, no plasma cell in 10 HPFs, thus Non-CD;grade 1, rare single plasma cells; grade 2, rare clusters or more than 5 single cells total; and grade 3, many plasma cells with more than 5 clusters, were examined and compared between Non-CE and CE., Results: The incidence rate of CD of grade2 + 3 was significantly higher in CE than Non-CE (53.8%; 7/13 vs. 0%; 0/13, P < 0.01). Presence of clusters or a number of plasma cells in 10 HPFs of decidua showed a sensitivity of 53.8%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 68.4% for the diagnosis of CE., Conclusion: Presence of clusters of plasma cells or five or more of plasma cells in decidua was found in more than half of CE, but not found in Non-CE. When CD with cluster or five or more of plasma cells is confirmed histologically in miscarriage decidual tissue, the presence of CE before the pregnancy should be suspected.

Aim: Chronic endometritis (CE) is a disease of continuous and subtle inflammation characterized by the infiltration of plasma cells in the endometrial stromal area. Although the clinical significance of CE has been thought in clinical practice for a long time because it is either asymptomatic or presents with subtle symptoms, recent studies have shown the potential adverse effects of CE on fertility. In the present review, we focus on the concept, diagnosis, etiology, pathophysiology, diagnosis, impact on reproduction and treatment for it to understand CE., Methods: The published articles were reviewed., Results: The prevalence of CE has been found to be 2.8-56.8% in infertile women, 14-67.5% in women with recurrent implantation failure (RIF), and 9.3-67.6% in women with recurrent pregnancy loss. Microorganisms are thought to be a main cause of CE, since antibiotic treatment has been reported to be an effective therapy for CE. Common bacteria are frequently detected in the uterine cavity of CE patients by microbial culture. In CE endometrium, the prevalence of immune cells and decidualization has been reported to be modified, and these modifications are thought to adversely affect fertility. The gold standard for the diagnosis of CE is the histological detection of plasma cells in the stromal area of the endometrium in endometrial specimens, although universally accepted criteria for the diagnosis of CE have not been determined. The treatment currently thought to be most effective for the recovery of fertility in CE is administration of oral antibiotics. Patients whose CE has been cured have been reported to have a higher ongoing pregnancy rate, clinical pregnancy rate, and implantation rate compared with patients with persistent CE., Conclusion: CE greatly affects implantation and impairs fertility. Antibiotic administration is an effective therapeutic option. Pregnancy rate in in vitro fertilization is improved when CE is cured by antibiotic., (© 2019 Japan Society of Obstetrics and Gynecology.)