Diets enriched in PUFAs at an early postimplantation stage prevent embryo resorptions and impaired mTOR signaling in the decidua from diabetic rats.

Maternal diabetes increases the risk of embryo resorptions and impairs embryo development. Decidualization is crucial for embryo development and regulated by mTOR signaling. However, little is known about how maternal diabetes affects the decidua at early postimplantation stages and whether dietary treatments enriched in polyunsaturated fatty acids (PUFAs) can prevent decidual alterations. Here, we determined resorption rates, decidual mTOR pathways and markers of decidual function and remodeling in diabetic rats fed or not with diets enriched in PUFAs exclusively during the early postimplantation period. Pregestational streptozotocin-induced diabetic Albino Wistar rats and controls were fed or not with diets enriched in 6% sunflower oil or 6% chia oil (enriched in n-6 or n-3 PUFAs, respectively) on days 7, 8 and 9 of pregnancy and evaluated on day 9 of pregnancy. Maternal diabetes induced an 11-fold increase in embryo resorptions, which was prevented by both PUFAs-enriched diets despite no changes in maternal glycemia. The activity of mTOR pathway was decreased in the decidua from diabetic rats, an alteration prevented by the PUFAs-enriched diets. PUFAs-enriched diets prevented increased expression of Foxo1 (a negative regulator of mTOR) and reduced expression of miR-21 (a negative regulator of Foxo1). These diets also prevented reduced markers of decidual function (leukemia inhibitory factor and IGFBP1 expression and MMPs activity) in diabetic rat decidua. We identified the early post implantation as a crucial stage for pregnancy success, in which dietary PUFAs can protect diabetic pregnancies from embryo resorptions, decidual mTOR signaling impairments, and altered markers of decidual function and remodeling.

Impact of Kuntai Capsules on LIF, IGF-1 and EGF expression in the implantation window of endometrium in mice / Impacto de cápsulas de Kuntai en la expresión de LIF, IGF-1 y EGF en la ventana de implantación de endometrio en ratones

To investigate the influence of Kuntai capsules on the expression level of leukemia inhibitory factor (LIF), insulin-like growth factor-I (IGF-1)and epidermal growth factor (EGF) during the mouse's implantation window of superovulation period and controlled ovarian hyperstimulation period. 90 female mice were randomly divided into six groups in control, superovulation and controlled ovarian hyperstimulation (COH) conditions. The RNA expression of EGF, LIF and IGF-1 in the endometrium on the 4th day of pregnancy was detected, and the relative expression was compared. mRNA expression of these three factors in endometrium was significantly lower in superovulation and COH groups than control group (p<0.001). mRNA expression of these three factors in endometrium remained obviously lower in superovulation plus kuntai capsule group and COH plus kuntai capsule group than control group (p<0.01). mRNA expression of these three factors in endometrium was lower in control group than in the NS plus kuntai capsule group (p<0.05). Kuntai capsule cannot completely reverse the endometrial damages caused by superovulation and COH. Thus Kuntai capsule could partially improve a mouse's endometrial receptivity during the implantation window.

Para investigar la influencia de las cápsulas de Kuntai en el nivel de expresión del factor inhibidor de la leucemia (LIF), el factor de crecimiento similar a la insulina I (IGF-1) y el factor de crecimiento epidérmico (EGF) durante la ventana de implantación del ratón del período de superovulación y la hiperestimulación ovárica controlada período, se dividieron aleatoriamente 90 ratones hembra en seis grupos en condiciones de control, superovulación e hiperestimulación ovárica controlada (COH). Se detectó la expresión de ARN de EGF, LIF e IGF-1en el endometrio al cuarto día de embarazo, y se comparó la expresión relativa. La expresión de ARNm de estos tres factores en el endometrio fue significativamente menor en los grupos de superovulación y COH que en el grupo control (p<0,001). La expresión de ARNm de estos tres factores en el endometrio permaneció más baja en el grupo de cápsulas de superovulación más Kuntai y en el grupo de cápsulas de COH más Kuntai respecto del grupo control (p<0,01). La expresión de ARNm de estos tres factores en el endometrio fue menor en el grupo control que en el grupo de cápsula NS más Kuntai (p<0,05). La cápsula de Kuntai no pudo revertir completamente los daños endometriales causados por la superovulación y la COH. Por lo tanto, se sugiere que la cápsula de Kuntai podría mejorar parcialmente la receptividad endometrial de un ratón durante la ventana de implantación.

Leukemia Inhibitory Factor Increases Survival of Pluripotent Stem Cell-Derived Cardiomyocytes.

Leukemia inhibitory factor (LIF) is a growth factor with pleiotropic biological functions. It has been reported that LIF acts at different stages during mesoderm development. Also, it has been shown that LIF has a cytoprotective effect on neonatal murine cardiomyocytes (CMs) in culture, but little is known about the role of LIF during human cardiogenesis. Thus, we analyzed the effects of LIF on human pluripotent stem cells (PSC) undergoing cardiac differentiation. We first showed that LIF is expressed in the human heart during early development. We found that the addition of LIF within a precise time window during the in vitro differentiation process significantly increased CMs viability. This finding was associated to a decrease in the expression of pro-apoptotic protein Bax, which coincides with a reduction of the apoptotic rate. Therefore, the addition of LIF may represent a promising strategy for increasing CMs survival derived from PSCs.

Alterations in expression of endometrial milk fat globule-EGF factor 8 (MFG-E8) and leukemia inhibitory factor (LIF) in patients with infertility and endometriosis.

OBJECTIVE: The aim of this study was to compare the endometrial expression of milk fat globule-EGF factor 8 (MFG-E8), its receptor integrin αvß3, and leukemia inhibitory factor (LIF) in patients with endometriosis and infertility and in healthy fertile patients during the window of implantation. METHODS: Five patients with peritoneal endometriosis and infertility (case group) and four healthy fertile patients (control group) were recruited. All patients were either diagnosed with or ruled out for endometriosis by laparoscopic surgery; the case group underwent surgery for infertility investigation and the control group for tubal ligation. Endometrial biopsies were performed in all patients during the window of implantation (LH+8 to LH+10), and then the samples were analyzed by immunochemistry for MFG-E8, integrin αvß3, and LIF. RESULTS: In patients with endometriosis and infertility, expression of MFG-E8 was significantly increased in the glandular epithelium when compared to healthy fertile patients (p<0.001). Moreover, LIF expression was lower in patients with endometriosis and infertility (p<0.05). Nevertheless, we found no difference in integrin αvß3 expression between the groups (p=0.084). CONCLUSION: This study showed for the first time that MFG-E8 expression is impaired in the endometrium of patients with endometriosis and infertility during the window of implantation. Moreover, LIF is also diminished in the endometrium of these patients as shown before.

Colony stimulating factor-1 and leukemia inhibitor factor expression from current-cycle cannula isolated endometrial cells are associated with increased endometrial receptivity and pregnancy.

BACKGROUND: Poor endometrial quality is associated with more than a third of embryo implantation failures. Current ultrasonography technology lacks the capacity to determine efficiently the endometrial receptivity during ongoing cycle transfers. We analyzed the relationship between the gene expression profile associated with implantation and clinical pregnancy from endometrial cells taken during embryo transfer. METHODS: Seventy-six patients submitted to a standard ovarian stimulation protocol, in vitro fertilization, and good quality embryos were collected (morphological assessment). Endometrial samples were taken with ultrasonography guidance and cells were Hematoxylin and Eosin stained for morphological identification. Total RNA was extracted and the expression of Mucin 1 (MUC1), Homeobox A10 (HOXA-10), Leukemia Inhibitor Factor (LIF), Colony Stimulating Factor-1 (CSF-1), and ribosomal 18 s (endogenous control) were analyzed using RT-qPCR. Presence of a gestational sac, ß-hGC (≥10 mIU/mL on Day 20), and a fetal heartbeat were used to determine a positive embryo implantation and pregnancy. RESULTS: Samples collected from same cycle embryo transfer showed clear morphological staining for endometrial cells (80-90% of the cells). Cells in the sample were molecularly identified as the endometrium (HOXA-10 positive and MUC-1 negative). CSF-1 expression was 4.55-fold and LIF expression was 12.25-fold higher in patients who became pregnant. Both increases were statistically significant (p < 0.05). CONCLUSIONS: Here, we provide evidence of a new method to assess endometrial receptivity. Furthermore, we demonstrate that the expression profile, based on LIF and CSF-1, showed a difference between a receptive and a non-receptive endometrium.

Absence of suppressor of cytokine signaling 2 turns cardiomyocytes unresponsive to LIF-dependent increases in Ca2+ levels.

Little is known regarding the role of suppressor of cytokine signaling (SOCS) in the control of cytokine signaling in cardiomyocytes. We investigated the consequences of SOCS2 ablation for leukemia inhibitory factor (LIF)-induced enhancement of intracellular Ca2+ ([Ca2+]i) transient by performing experiments with cardiomyocytes from SOCS2-knockout (ko) mice. Similar levels of SOCS3 transcripts were seen in cardiomyocytes from wild-type and SOCS2-ko mice, while SOCS1 mRNA was reduced in SOCS2-ko. Immunoprecipitation experiments showed increased SOCS3 association with gp130 receptor in SOCS2-ko myocytes. Measurements of Ca2+ in wild-type myocytes exposed to LIF showed a significant increase in the magnitude of the Ca2+ transient. This change was absent in LIF-treated SOCS2-ko cells. LIF activation of ERK and STAT3 was observed in both wild-type and SOCS2-ko cells, indicating that in SOCS2-ko, LIF receptors were functional, despite the lack of effect in the Ca2+ transient. In wild-type cells, LIF-induced increase in [Ca2+]i and phospholamban Thr17 [PLN(Thr17)] phosphorylation was inhibited by KN-93, indicating a role for CaMKII in LIF-induced Ca2+ raise. LIF-induced phosphorylation of PLN(Thr17) was abrogated in SOCS2-ko myocytes. In wild-type cardiomyocytes, LIF treatment increased L-type Ca2+ current (ICa,L), a key activator of CaMKII in response to LIF. Conversely, SOCS2-ko myocytes failed to activate ICa,L in response to LIF, providing a rationale for the lack of LIF effect on Ca2+ transient. Our data show that absence of SOCS2 turns cardiomyocytes unresponsive to LIF-induced [Ca2+] raise, indicating that endogenous levels of SOCS2 are crucial for full activation of LIF signaling in the heart.

Effects of modified Shoutaiwai recipe on integrin ß3 and leukemia-inhibitory factor in endometrium of controlled ovarian hyperstimulation mice during the implantation window.

We investigated the effects of a modified Shoutaiwai recipe on integrin ß3 and leukemia-inhibitory factor (LIF) in the endometrium of controlled ovarian hyperstimulation (COH) mice during the implantation window. Seventy non-pregnant mice were randomly divided into 3 groups: a traditional medicine (TCM) treatment group (N = 30), an aspirin treatment (N = 30) group, and a control group (N = 10). After the model was successfully established, mice in the drug treatment groups and the control group were respectively treated with the modified Shoutaiwai recipe, aspirin, or 0.9% physiological saline. During the implantation window of mice, the middle segment of the mouse uterus was recovered, and integrin ß3 and LIF expressions in the endometrium were respectively detected using an immunohistological two-step method and reverse transcription-PCR. Expressions of integrin ß3 and LIF in the endometrium of mice in the TCM treatment group were significantly increased compared to aspirin-treated and control mice, and those of aspirin-treated mice were increased compared to the control group. Our modified Shoutaiwai recipe may improve the endometrial receptivity of COH mice by increasing the expression of integrin ß3 and LIF in the endometrium during the implantation window.

Lipopolysaccharides and trophic factors regulate the LPS receptor complex in nodose and trigeminal neurons.

Binding of bacterial lipopolysaccharides (LPS) to toll-like receptor 4 (TLR4) triggers an innate immunoresponse associated with pain and inflammation. The expression, and to a greater extent the regulation of TLR4 and its auxiliary proteins (myeloid differentiation protein 1 (MD1), myeloid differentiation protein 2 (MD2) and cluster of differentiation 14 (CD14)), are both poorly understood in trigeminal and nodose neurons. We used a combination of Western blotting, semi-quantitative polymerase chain reaction (PCR), pharmacological manipulation and immunohistochemistry. The expression pattern and regulation by LPS and trophic factors of TLR4/MD2/CD14 and radioprotective protein of 105kDa (RP105)/MD1 were determined in neonatal trigeminal and nodose mice neurons. We found that all these proteins were expressed in both trigeminal and nodose neurons. The trophic factors Artemin and nerve growth factor (NGF) up-regulated MD2 and RP105 mRNA levels in trigeminal neurons. In nodose neurons the trophic factors brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF) up-regulated MD1 and RP105 mRNA levels. Also we observed that in both neuronal types LPS acutely (within 20 min) down-regulated CD14 and MD2 mRNAs. In addition, LPS increased significantly the proportion of trigeminal and nodose neurons expressing nociceptin/orphanin FQ in culture probably acting via TLR4/MD2. Although the exact mechanisms underlying the regulation by trophic factors and LPS require further elucidation, the findings of this study indicate that LPS acts through its archetypical receptor in trigeminal and nodose neurons.

Construction and identification of pIRES2-LIF-NT-3 bicistronic eukaryotic expression vector.

We used a simple and efficient method to construct a bicistronic eukaryotic expression vector pIRES2-LIF-NT-3. The leukemia inhibitory factor (LIF) and neurotrophin-3 (NT-3) genes were obtained from the genomic DNA of human peripheral blood mononuclear cells by polymerase chain reaction. The LIF cDNA fragment was inserted into the multiple cloning sites of a vector containing internal ribosome entry site and enhanced green fluorescent protein (EGFP) (pIRES2-EGFP) to generate the bicistronic eukaryotic expression plasmid pIRES2-LIF-EGFP. Next, the NT-3 cDNA fragment was cloned into pIRES2-LIF-EGFP in place of EGFP to create the plasmid pIRES2-LIF-NT-3. pIRES2-LIF-NT-3 was transfected into HEK293 cells and reverse transcription-polymerase chain reaction and Western blotting were used to test the co-expression of double genes. LIF and NT-3 genes were cloned and the DNA was sequenced. Sequencing analysis revealed that LIF and NT-3 were consistent with the sequence recorded in GenBank. Restriction analysis indicated that the LIF and NT-3 genes were inserted correctly into the expression vector pIRES2-EGFP. Following transfection of pIRES2-LIF-NT-3 into HEK293 cells, the double gene was expressed at the mRNA and protein levels. The LIF and NT-3 coexpression plasmid is a novel expression system that will enable further study of the functions of the LIF and NT-3 genes.

Progesterone is essential for protecting against LPS-induced pregnancy loss. LIF as a potential mediator of the anti-inflammatory effect of progesterone.

Lipopolysaccharide (LPS) administration to mice on day 7 of gestation led to 100% embryonic resorption after 24 h. In this model, nitric oxide is fundamental for the resorption process. Progesterone may be responsible, at least in part, for a Th2 switch in the feto-maternal interface, inducing active immune tolerance against fetal antigens. Th2 cells promote the development of T cells, producing leukemia inhibitory factor (LIF), which seems to be important due to its immunomodulatory action during early pregnancy. Our aim was to evaluate the involvement of progesterone in the mechanism of LPS-induced embryonic resorption, and whether LIF can mediate hormonal action. Using in vivo and in vitro models, we provide evidence that circulating progesterone is an important component of the process by which infection causes embryonic resorption in mice. Also, LIF seems to be a mediator of the progesterone effect under inflammatory conditions. We found that serum progesterone fell to very low levels after 24 h of LPS exposure. Moreover, progesterone supplementation prevented embryonic resorption and LPS-induced increase of uterine nitric oxide levels in vivo. Results show that LPS diminished the expression of the nuclear progesterone receptor in the uterus after 6 and 12 h of treatment. We investigated the expression of LIF in uterine tissue from pregnant mice and found that progesterone up-regulates LIF mRNA expression in vitro. We observed that LIF was able to modulate the levels of nitric oxide induced by LPS in vitro, suggesting that it could be a potential mediator of the inflammatory action of progesterone. Our observations support the view that progesterone plays a critical role in a successful pregnancy as an anti-inflammatory agent, and that it could have possible therapeutic applications in the prevention of early reproductive failure associated with inflammatory disorders.

Liver sinusoidal endothelial cells support the survival and undifferentiated growth of the CGR8 mouse embryonic stem cell line: possible role of leukemia inhibitory factor (LIF).

Murine embryonic stem cells (muESC) are maintained and expanded in vitro by culturing in the presence of leukemia inhibitory factor (LIF) or by coculturing on murine embryonic fibroblast (MEF). Previously we have shown that liver sinusoidal endothelial cells (LSEC) promote the survival, proliferation and differentiation of hematopoietic stem cells. In the present study we investigated whether LSEC might promote the survival and undifferentiated growth of muESC. For these purposes, muESC (CGR8 cell line) were cultured on LSEC monolayers (muESC/LSEC) or in the presence of conditioned medium from LSEC cultures (muESC/LSEC-CM), both in the absence of LIF. Microscopic observation showed the growth of undifferentiated ESC colonies in both muESC/LSEC or muESC/LSEC-CM cultures. A significant reduction in the growth of undifferentiated ESC colonies was observed when ESC were cultured in LSEC-CM previously incubated with anti-LIF. RT-PCR and Western blot analysis showed that LSEC constitutively express LIF at the mRNA and protein level. At different times of culture, muESC were harvested and analyzed for the expression of embryonic markers (SSEA-1 and Oct-4) and differentiation capacity. Flow cytometry analysis showed the presence of a higher percentage of muESC (>90%) expressing SSEA-1 in muESC/LSEC-CM, as compared with muESC/LSEC cocultures. muESC obtained from both types of cultures formed embryoid bodies in vitro, and form teratomas in testicles of mice. These results provide the first evidence that LSEC support the in vitro survival, self-renewal, undifferentiated growth and differentiation capacity of the muESC CGR8 cell line.

Modulation of maternal LIF producers T cells by trophoblast and paternal antigens.

PROBLEM: Fetal implantation enhances the production of essential growth factors such as LIF (leukaemia inhibitory factor), hence we investigated the contribution of maternal CD4 cells, activated by paternal or trophoblast antigens and its modulation by VIP (vasoactive intestinal peptide) and progesterone. METHOD OF STUDY: We performed co cultures of trophoblast cells (Swan-71 cell line) or paternal antigens and PBMCs from patients with recurrent spontaneous abortions (RSA) and fertile women. RESULT: Fertile-CD4(+) LIF(+) cells were increased by VIP and progesterone in response to paternal and trophoblast antigens. Also MMP-9 activity was decreased and pSTAT3/STAT3 ratio was increased. RSA patients have decreased levels of LIF expression which could not be modulated by VIP and progesterone and displayed a reduced number of endometrial infiltrated CD4(+) LIF(+) cells compared with fertile women. CONCLUSION: The decrease of CD4(+) LIF(+) cells in RSA patients could be related with the exacerbated inflammatory response observed in the maternal-fetal dialogue model.

Glucocorticoid-induced impairment of mammary gland involution is associated with STAT5 and STAT3 signaling modulation.

The mammary epithelium undergoes cyclical periods of cellular proliferation, differentiation, and regression. During lactation, the signal transducer and activator of transcription factor (STAT)-5A and the glucocorticoid receptor (GR) synergize to induce milk protein expression and also act as survival factors. During involution, STAT3 activation mediates epithelial cell apoptosis and mammary gland remodeling. It has been shown that the administration of glucocorticoids at weaning prevents epithelial cell death, probably by extracellular matrix breakdown prevention. Our results show that the synthetic glucocorticoid dexamethasone (DEX) modulates STAT5A and STAT3 signaling and inhibits apoptosis induction in postlactating mouse mammary glands, only when administered within the first 48 h upon cessation of suckling. DEX administration right after weaning delayed STAT5A inactivation and degradation, preserving gene expression of target genes as ß-casein (bcas) and prolactin induced protein (pip). Weaning-triggered GR down-regulation is also delayed by the hormone treatment. Moreover, DEX administration delayed STAT3 activation and translocation into epithelial cells nuclei. In particular, DEX treatment impaired the increment in gene expression of signal transducer subunit gp130, normally up-regulated from lactation to involution and responsible for STAT3 activation. Therefore, the data shown herein indicate that glucocorticoids are able to modulate early involution by controlling the strong cross talk that GR, STAT5, and STAT3 pathways maintains in the mammary epithelium.

Tumor necrosis factor alpha induces LIF expression through ERK1/2 activation in mammary epithelial cells.

It has been reported that expression of tumor necrosis factor superfamily members occur at the onset of the mammary gland post-lactational involution. One of these proteins, tumor necrosis factor alpha (TNFalpha), is a major mediator of inflammation that is able to induce expression of several cytokines. Leukemia inhibitory factor (LIF) is an inflammatory cytokine that is induced and plays a fundamental role during post-lactational involution of the mammary gland. Therefore, our goal was to determine whether TNFalpha activity in the mammary epithelium might include regulation of LIF expression. This biological role would increase the significance of TNFalpha expression at the end of lactation. Our results show that TNFalpha was able to induce LIF transcription through ERK1/2 activation in a non-tumorigenic mouse mammary epithelial cell line, SCp2. We found that activation of TNFalpha receptor-2 (TNFR2) was specifically involved in triggering this signaling pathway. In addition, our data suggest the participation of AP-1 transcription factor family members in this pathway. We determined that TNFalpha treatment induced c-fos transcription, and blocking AP-1 activity resulted in a significant inhibition of TNFalpha-induced LIF expression. Finally, we found that TNFalpha was also able to trigger LIF expression and ERK1/2 activation in the mouse mammary gland in vivo. Therefore, our data suggest that TNFalpha may contribute to mammary gland involution by, among other activities, eliciting LIF expression through ERK1/2 and AP1 activation.

The role of p38 mitogen-activated protein kinase in serum-induced leukemia inhibitory factor secretion by bone marrow stromal cells from pediatric myelodysplastic syndromes.

Stromal cells from pediatric myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) associated with MDS (MDS-AML) present high expression of leukemia inhibitor factor (LIF). We demonstrated using mitogen-activated protein kinase (MAPK) inhibitors that in stromal cells from pediatric MDS and MDS-AML, p38MAPK was critical in serum-induced secretion of LIF. The serum induction of phosphorylated p38MAPK form was observed only in stromal cells from healthy children, whereas in MDS and MDS-AML basal levels were maintained suggesting constitutive p38MAPK activation. Our study suggested the possible importance in pediatric MDS of p38MAPK signaling pathway which may be a future therapeutic target.

Mechanical strain induces involution-associated events in mammary epithelial cells.

BACKGROUND: Shortly after weaning, a complex multi-step process that leads to massive epithelial apoptosis is triggered by tissue local factors in the mouse mammary gland. Several reports have demonstrated the relevance of mechanical stress to induce adaptive responses in different cell types. Interestingly, these signaling pathways also participate in mammary gland involution. Then, it has been suggested that cell stretching caused by milk accumulation after weaning might be the first stimulus that initiates the complete remodeling of the mammary gland. However, no previous report has demonstrated the impact of mechanical stress on mammary cell physiology. To address this issue, we have designed a new practical device that allowed us to evaluate the effects of radial stretching on mammary epithelial cells in culture. RESULTS: We have designed and built a new device to analyze the biological consequences of applying mechanical stress to cells cultured on flexible silicone membranes. Subsequently, a geometrical model that predicted the percentage of radial strain applied to the elastic substrate was developed. By microscopic image analysis, the adjustment of these calculations to the actual strain exerted on the attached cells was verified. The studies described herein were all performed in the HC11 non-tumorigenic mammary epithelial cell line, which was originated from a pregnant BALB/c mouse. In these cells, as previously observed in other tissue types, mechanical stress induced ERK1/2 phosphorylation and c-Fos mRNA and protein expression. In addition, we found that mammary cell stretching triggered involution associated cellular events as Leukemia Inhibitory Factor (LIF) expression induction, STAT3 activation and AKT phosphorylation inhibition. CONCLUSION: Here, we show for the first time, that mechanical strain is able to induce weaning-associated events in cultured mammary epithelial cells. These results were obtained using a new practical and affordable device specifically designed for such a purpose. We believe that our results indicate the relevance of mechanical stress among the early post-lactation events that lead to mammary gland involution.

Protein profile of the luteal phase endometrium by tissue microarray assessment.

To investigate the luteal phase endometrial expression of leukemia inhibitor factor (LIF), insulin-like growth factor 1 (IGF-1), progesterone receptor (PR), claudin 4 (CLDN4), vascular-endothelial growth factor receptor 3 (VEGFR-3), bone morphogenetic protein 4 (BMP-4) and citokeratin 7 (CK-7), we obtained luteal phase endometrial samples from 52 women. Samples were dated and integrated using a tissue microarray (TMA). Samples were immunostained for LIF, IGF-1, PR, CLDN4, VEGFR-3, BMP-4 and CK-7. Frequencies of positive expressions at the early, mid and late luteal phases were compared by two proportions test. Concomitant expression of these proteins was assessed with Chi-square or Fischer's test. The frequency of LIF was positively correlated to the frequency of IGF-1 (r = 0.99; p < 0.05) and PR (r = 0.99; p < 0.05), and the correlation between IGF-1 and PR tended to be significant (r = 0.98; p < 0.1). The expression of PR was associated with the absence of CLDN4 (p < 0.001). Thus, expression of LIF, IGF-1 and PR are correlated during the luteal phase, and immunohistochemistry for these proteins might be used to assist in the assessment of endometrial maturation. In addition, the expression of CLDN4 and PR was not concomitant, warranting further investigation on the relationship of their endometrial expression.

Endometrial claudin-4 and leukemia inhibitory factor are associated with assisted reproduction outcome.

BACKGROUND: Claudin-4 (CLDN4) is one of several proteins that act as molecular mediators of embryo implantation. Recently, we examined immunolabeling of leukemia inhibitory factor (LIF) in the endometrial tissue of 52 IVF patients, and found that LIF staining intensity was strongly correlated with successful pregnancy initiation. In the same set of patients, we have now examined endometrial CLDN4 expression, to see how expression intensity may vary with LIF. We examined CLDN4 in the luteal phase of the menstrual cycle, immediately preceding IVF treatment. Our aim was to compare expression of LIF and CLDN4 in the luteal phase, and document these patterns as putative biomarkers for pregnancy. METHODS: Endometrial tissue was collected from women undergoing IVF. Endometrial biopsies were obtained during the luteal phase preceding IVF, and were then used for tissue microarray (TMA) immunolabeling of CLDN4. Previously published LIF expression data were then combined with CLDN4 expression data, to determine CLDN4/LIF expression patterns. Associations between successful pregnancy after IVF and combined CLDN4/LIF expression patterns were evaluated. RESULTS: Four patterns of immunolabeling were observed in the endometrial samples: 16% showed weak CLDN4 and strong LIF (CLDN4-/LIF+); 20% showed strong CLDN4 and strong LIF (LIF+/CLDN4+); 28% showed strong CLDN4 and weak LIF (CLDN4+/LIF-); and 36% showed weak CLDN4 and weak LIF (CLDN4-/LIF-). Successful implantation after IVF was associated with CLDN4-/LIF+(p = 0.003). Patients showing this endometrial CLDN4-/LIF+ immunolabeling were also 6 times more likely to achieve pregnancy than patients with endometrial CLDN4+/LIF- immunolabeling (p = 0.007). CONCLUSION: The combined immunolabeling expression of CLDN4-/LIF+ in endometrial tissue is a potential biomarker for predicting successful pregnancy in IVF candidates.

Endometrial leukemia inhibitory factor as a predictor of pregnancy after in vitro fertilization.

OBJECTIVE: To determine whether there is an association between endometrial expression of leukemia inhibitory factor (LIF) in the luteal phase of the menstrual cycle preceding in vitro fertilization (IVF) and treatment outcome. METHODS: Biopsy specimens from the endometria of 52 women in the luteal phase were immunostained against LIF. Embryo culture and transfer were done according to standard procedures. RESULTS: Clinical pregnancy occurred in 39% of the women following IVF, and strong endometrial immunohistochemical staining for LIF was associated with pregnancy (P=0.01). The women with a strong LIF expression had a 6.4-fold higher chance of becoming pregnant than those with weaker intensities (P=0.005). CONCLUSION: Endometrial expression of LIF during the luteal phase can be used as a predictor of IVF success.

The influence of hydrosalpinx on markers of endometrial receptivity.

Hydrosalpinx is a common condition among women of reproductive age. It is related to low pregnancy rates in the settings of in vitro fertilization-embryo transfer programs. Such low rates are not yet well understood, and may be due to poor endometrial receptivity and abnormal expression of key molecules in the endometrium that are important for implantation. The available data on the inflammatory response, endometrial blood flow, integrins, leukemia inhibitory factor, matrix metalloproteinases, and homeobox gene A10 expression in the presence of hydrosalpinx are reviewed. In addition, the evidence for treatment options to improve pregnancy rates is also discussed.