Role of intrauterine administration of transfected peripheral blood mononuclear cells by GM-CSF on embryo implantation and pregnancy rate in mice

GM-CSF improves endometrial receptivity in a thin endometrium rat model by upregulating HOXA10

Endometrial receptivity is a prerequisite for the success of assisted reproduction. Patients with a consistently thin endometrium frequently fail to conceive, owing to low endometrial receptivity, and there are currently very few therapeutic options available. Our previous study demonstrated that intrauterine granulocyte-macrophage colony-stimulating factor (GM-CSF) administration resulted in a significant improvement in clinical pregnancy and implantation rates and was an effective means of increasing endometrial thickness on the day of embryo transfer in patients with thin endometrium. In order to explore the underlying process, an animal model with a thin endometrium was constructed, the homeobox A10 gene (HOXA10) was downregulated, and an inhibitor of the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway (MAPK/ERK) was employed. Our findings strongly suggest a marked decrease in GM-CSF levels in the thin endometrial rat model, and the suppression of HOXA10 impeded the therapeutic efficacy of GM-CSF in this model. Moreover, we showed that GM-CSF significantly increases endometrial receptivity in the rat model and upregulates HOXA10 via the MAPK/ERK pathway. Our data provide new molecular insights into the mechanisms underlying formation of a thin endometrium and highlight a novel, potential clinical treatment strategy as well as directions for further research.

Effects of human chorionic gonadotropin-producing peripheral blood mononuclear cells on the endometrial receptivity and implantation sites of the mouse uterus

OBJECTIVE

This research investigated the effects of human chorionic gonadotropin (HCG)-producing peripheral blood mononuclear cells (PBMCs) on the implantation rate and embryo attachment in mice.

METHODS

In this experimental study, a DNA fragment of the HCG gene was cloned into an expression vector, which was transfected into PBMCs. The concentration of the produced HCG was measured using enzyme-linked immunosorbent assay. Embryo attachment was investigated on the co-cultured endometrial cells and PBMCs in vitro. As an in vivo experiment, intrauterine administration of PBMCs was done in plaque-positive female mice. Studied mice were distributed into five groups: control, embryo implantation dysfunction (EID), EID with produced HCG, EID with PBMCs, and EID with HCG-producing PBMCs. Uterine horns were excised to characterize the number of implantation sites and pregnancy rate on day 7.5 post-coitum. During an implantation window, the mRNA expression of genes was evaluated using real-time polymerase chain reaction.

RESULTS

DNA fragments were cloned between the BamHI and EcoRI sites in the vector. About 465 pg/mL of HCG was produced in the transfected PBMCs. The attachment rate, pregnancy rate, and the number of implantation sites were substantially higher in the HCG-producing PBMCs group than in the other groups. Significantly elevated expression of the target genes was observed in the EID with HCG-producing PBMCs group.

CONCLUSION

Alterations in gene expression following the intrauterine injection of HCG-producing PBMCs, could be considered a possible cause of increased embryo attachment rate, pregnancy rate, and the number of implantation sites.

Chronic, acute and protocol-dependent effects of exercise on psycho-physiological health during long-term isolation and confinement

Exercise could prevent physical and psychological deteriorations, especially during pandemic times of lock-down scenarios and social isolation. But to meet both, the common exercise protocols require optimization based on holistic investigations and with respect to underlying processes. This study aimed to explore individual chronic and acute effects of continuous and interval running exercise on physical and cognitive performance, mood, and affect and underlying neurophysiological factors during a terrestrial simulated space mission. Six volunteers (three females) were isolated for 120 days. Accompanying exercise training consisted of a continuous and interval running protocol in a cross-over design. Incremental stage tests on a treadmill were done frequently to test physical performance. Actigraphy was used to monitor physical activity level. Cognitive performance, mood (MoodMeter®), affect (PANAS), brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1), vascular-endothelial growth factor (VEGF), and saliva cortisol were investigated prior to, four times during, and after isolation, pre- and post-exercise on two separate days, respectively. As a chronic effect, physical performance increased (and IGF-1 tended) in the course of isolation and training until the end of isolation. Subjective mood and affect state, as well as cognitive performance, basal BDNF and VEGF levels, were well-preserved across the intervention. No acute effects of exercise were detected, besides slower reaction time after exercise in two out of nine cognitive tests, testing sensorimotor speed and memory of complex figures. Consistently higher basal IGF-1 concentrations and faster reaction time in the psychomotor vigilance test were found for the continuous compared to the interval running protocol. The results suggest that 120 days of isolation and confinement can be undergone without cognitive and mental deteriorations. Regular, individual aerobic running training supporting physical fitness is hypothesized to play an important role in this regard. Continuous running exercise seems to trigger higher IGF-1 levels and vigilance compared to interval running. Systematic and prolonged investigations and larger sample size are required to follow up on exercise-protocol specific differences in order to optimize the exercise intervention for long-term psycho-physiological health and well-being.

The expressions of matrix metalloproteinase-9, estrogen receptor, and progesterone receptor in thin endometrial tissue and their significance

OBJECTIVE

This study aims to investigate the expressions of matrix metalloproteinase-9 (MMP-9), estrogen receptor (ER), and progesterone receptor (PR) in thin endometrium.

METHODS

Patients who received treatment in our hospital between January 2018 and September 2020 were enrolled. Endometrial thickness was measured using transvaginal ultrasound; in patients with a midluteal phase endometrial thickness of <7 mm, a sample of endometrial tissue was obtained using a hysteroscope, and the MMP-9, ER, and PR expressions were detected using immunohistochemistry. In addition, the number of endometrial glands was calculated in a complete field of view under a low-power (100×) microscope, and the serum estrogen and progesterone levels were determined. Following hormone therapy, the midluteal phase endometrial thickness was measured again using transvaginal ultrasound, and the patients were divided into two groups: the thin endometrium group and the normal endometrium group (n = 50, each). Patients in the thin endometrium group had an endometrial thickness of <7 mm, while patients in the normal endometrium group had an endometrial thickness of 7-10 mm.

RESULTS

The number of endometrial glands as well as the ER and MMP-9 expressions were lower in the thin endometrium group than in the normal endometrium group; the differences were statistically significant (p < .05). The receiver operator characteristic curve revealed that ER and MMP-9 had a high prediction accuracy in patients with refractory thin endometrium, while the number of endometrial glands was moderately predictive.

CONCLUSION

Compared with other patients with thin endometrium, patients with refractory thin endometrium had a reduced the number of endometrial glands and significantly lower ER and MMP-9 expressions.

Effects of human chorionic gonadotropin intrauterine injection on oocyte retrieval day on assisted reproductive techniques outcomes: An RCT

Background

Several mediators play an important role in implantation. One of these mediators is human chorionic gonadotropin (HCG).

Objective

To evaluate the effects of HCG intrauterine injection on the day of oocyte retrieval on the result of assisted reproductive techniques (ART).

Materials and Methods

In this randomized clinical trial study, 126 women who were referred to Afzalipour Infertility Center between December 2018 to December 2019 undergoing in vitro fertilization/intracytoplasmic sperm injection cycles were enrolled and assigned to two groups of: a case (n = 62) and a control group (n = 64). The protocols for both groups were the same; except that the case group was injected with the protocols for both groups were the same, except that the case group was injected with 1000 IU of HCG into uterine cavity following the oocyte puncture, while no medication was administered to the control group. The implantation rate, chemical pregnancy, clinical pregnancy, and abortion rates were compared between the two groups.

Results

Positive chemical pregnancy was seen in 15 (27.3%) cases of the case group and 14 (25.5%) of the control group. No significant difference was seen in the chemical and clinical pregnancy rates between the groups. The abortion rate was higher in the control group but that was not significant.

Conclusion

A 1000 IU of HCG intrauterine injection after oocyte retrieval does not improve implantation, chemical or clinical pregnancy rates in ART cycles. Further studies are needed to clearly understand the role of HCG intrauterine injection in the day of oocyte retrieval in ART outcomes.

IL-6/STAT3 signaling pathway regulates the proliferation and damage of intestinal epithelial cells in patients with ulcerative colitis via H3K27ac

The aim of the present study was to investigate the effect of the IL-6/STAT3 signaling pathway on intestinal epithelial barrier injury in patients with ulcerative colitis (UC). Fifty-two patients with UC and 21 healthy subjects were recruited. The expression level of IL-6 in plasma was determined by ELISA. Normal human colon mucosal epithelial NCM460 cells were treated with IL-6 or plasma from the patients with UC. Then, the transepithelial electrical resistance value, fluorescein yellow permeability and zonulin release were evaluated. Using reverse transcription-quantitative (q)PCR and western blotting, claudin (CLDN) 1 and CLDN2 expression levels were analyzed. Furthermore, western blotting was used to detect phosphorylation of STAT3. Chromatin immunoprecipitation-qPCR was performed to investigate the enrichment of H3K27ac in the promoter regions of CLDN1 and CLDN2. The present study revealed that IL-6 content was elevated in the plasma from patients with UC and increased with the progression of the disease. IL-6 was also observed to induce intestinal epithelial cell barrier injury and regulate barrier function by influencing the expression of tight junction-related proteins, as well as STAT3. The IL-6/STAT3 signaling pathway regulated transcription of CLDN1 and CLDN2 by affecting the enrichment of histone H3K27ac in their promoter regions. Thus, the significantly increased expression level of IL-6 in the peripheral blood of patients with UC indicates a positive association with the development of UC. Furthermore, the IL-6/STAT3 signaling pathway influences the function of the intestinal barrier by affecting the H3K27ac level in intestinal epithelial cells.

Toll-like receptor 2/4 inhibitors can reduce preterm birth in mice

Objectives

Preterm birth (PTB) occurs in 5% to 18% of newborns. However, the underlying inflammatory mechanisms have not been elucidated.

Methods

We established a mouse model of infection-associated PTB. Physical signs in pregnant mice with or without lipopolysaccharide (LPS) treatment were observed, and the frequencies of Toll-like receptor (TLR)2- and TLR4-positive CD11b+ cells were analyzed. Cytokine levels in plasma and pathological changes were assessed following LPS treatment. A rescue experiment was used to probe potential immunologic mechanisms underlying PTB.

Results

Lymphocyte infiltration could be observed in the placentas of mice following intrauterine injection with LPS. The percentage of inflammatory cells decreased 12 hours after treatment. Moreover, TLR2 and TLR4 expression in peripheral blood cells was significantly increased 4 hours after intraperitoneal injection of LPS. Peak TLR2 and TLR4 expression in peripheral blood cells occurred 8 hours post-treatment. TLR4 and TLR-2/4 inhibitors reduced levels of interleukin-10, interferon-γ, and tumor necrosis factor-α in peripheral blood and delayed PTB.

Conclusions

TLR2 and TLR4 inhibition could play important roles in PTB.

Decidua-derived granulocyte macrophage colony-stimulating factor induces polymorphonuclear myeloid-derived suppressor cells from circulating CD15+ neutrophils

STUDY QUESTION

Do decidua-derived factors stimulate the conversion of circulating neutrophils to polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) in early human pregnancy?

SUMMARY ANSWER

Circulating neutrophils can acquire PMN-MDSC-like phenotypes and function via phosphorylated signal transducer and activator of transcription 5/programmed death ligand 2 (pSTAT5/PD-L2) signalling after stimulation with decidua-derived granulocyte macrophage colony-stimulating factor (GM-CSF).

WHAT IS KNOWN ALREADY

PMN-MDSCs are an important immunoregulatory cell type in early pregnancy. Neutrophils are of high heterogeneity and plasticity and can polarize to immunosuppressive PMN-MDSCs upon stimulation.

STUDY DESIGN, SIZE, DURATION

For analysis of myeloid-derived suppressor cell (MDSC) subset proportions, 12 endometrium tissues and 12 peripheral blood samples were collected from non-pregnant women, and 40 decidua tissues and 16 peripheral blood samples were obtained from women with normal early pregnancy undergoing elective surgical pregnancy termination for nonmedical reasons with gestation age of 6-10 weeks. Twenty-nine decidua tissues were collected for isolation of CD15+ PMN-MDSCs. Twenty endometrium tissues and 30 decidua tissues were collected for cytokine analysis, immunohistochemistry or neutrophil stimulation. Peripheral blood samples were obtained from 36 healthy donors for isolation of CD3+ T cells and CD15+ neutrophils.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The proportion of MDSC subsets in the decidua and peripheral blood of normal early pregnancy, endometrium and peripheral blood of non-pregnant women was analysed by flow cytometry. The phenotypes and function of decidual PMN-MDSCs and circulating neutrophils were compared by flow cytometry. Circulating neutrophils were stimulated with decidual explant supernatant (DES) and the phenotypes were measured by flow cytometry and immunofluorescence. The suppressive capacity of decidual PMN-MDSCs and DES-conditioned neutrophils was analysed by flow cytometry with or without anti-programmed cell death-1 (PD-1) antibody. Cytokines from DES and endometrial explant supernatant (EES) were detected by a Luminex assay. GM-CSF expression was determined by ELISA and immunohistochemistry. Neutrophils were stimulated with DES, EES, DES with anti-GM-CSF antibody or EES with GM-CSF. CD11b, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), PD-L2 and pSTAT5 expression were measured by flow cytometry.

MAIN RESULTS AND THE ROLE OF CHANCE

The frequency of PMN-MDSCs was significantly increased in the decidua of early pregnancy compared with peripheral blood of non-pregnant women, the endometrium of non-pregnant women or peripheral blood during early pregnancy. Decidual PMN-MDSCs suppressed T-cell proliferation and cytokine production. Phenotypes of decidual PMN-MDSCs were similar to mature activated neutrophils. DES-induced CD11b, LOX-1, PD-L2 expression and STAT5 phosphorylation in neutrophils. The PD-L2 expression in neutrophils was dependent on STAT5 phosphorylation. Both decidual PMN-MDSCs and DES-conditioned neutrophils suppressed T-cell proliferation via PD-1 signalling. GM-CSF was up-regulated in the decidua and induced CD11b, LOX-1 and PD-L2 expression on neutrophils. DES significantly induced CD11b, LOX-1, PD-L2 expression and STAT5 phosphorylation. Anti-GM-CSF antibody remarkably blocked such stimulation in neutrophils. EES did not induce CD11b, LOX-1, PD-L2 expression or STAT5 phosphorylation, while GM-CSF treatment sufficiently stimulated CD11b, LOX-1, PD-L2 expression and STAT5 phosphorylation in neutrophils.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

The study was based on in vitro experiments and we were not able to evaluate neutrophils differentiation to PMN-MDSCs in other sites before entering the maternal-foetal interface due to the limited availability of human samples. This needs to be explored using murine models.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first study demonstrating that decidual PMN-MDSCs are a group of immunoregulatory cells with mature status, and that neutrophils can be induced to a PMN-MDSC-like phenotype with decidua-derived GM-CSF via pSTAT5/PD-L2 signalling. This study indicates that GM-CSF can facilitate immune tolerance of early pregnancy through regulating PMN-MDSCs and further provides a potential role of GM-CSF in prevention and treatment for pregnancy complications.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Natural Science Foundation of China (81671481) and National Natural Science Foundation of China (81871179). All authors have no competing interests to declare.