Leukemia inhibitory factor gene mutations in the population of infertile women are not restricted to nulligravid patients

Endogenous progesterone in unexplained infertility: a systematic review and meta-analysis

PURPOSE

To investigate the possibility that altered actions of endogenous progesterone affect receptivity and contribute to unexplained infertility (UI).

METHODS

Two authors electronically searched MEDLINE, CINAHL and Embase databases from inception to 6 July 2022 and hand-searched according to Cochrane methodology. We included all published primary research reporting outcomes related to endogenous progesterone in natural cycles in women with UI. Studies were assessed for risk of bias using a modified Newcastle-Ottawa Score or NHLBI Score. We pooled results where appropriate using a random-effects model. Findings were reported as odds ratios or mean differences.

RESULTS

We included 41 studies (n = 4023). No difference was found between the mid-luteal serum progesterone levels of women with UI compared to fertile controls (MD 0.74, - 0.31-1.79, I² 36%). Women with UI had significantly higher rates of 'out-of-phase' endometrium than controls. Nine out of 10 progesterone-mediated markers of endometrial receptivity were significantly reduced in women with UI compared to fertile controls (the remaining 1 had conflicting results). Resistance in pelvic vessels was increased and perfusion of the endometrium and sub-endometrium reduced in UI compared to fertile controls in all included studies. Progesterone receptor expression and progesterone uptake were also reduced in women with unexplained infertility.

CONCLUSIONS

End-organ measures of endogenous progesterone activity are reduced in women with UI compared to fertile controls. This apparently receptor-mediated reduction in response affects endometrial receptivity and is implicated as the cause of the infertility. Further research is required to confirm whether intervention could overcome this issue, offering a new option for treating unexplained infertility.

TRIAL REGISTRATION

PROSPERO registration: CRD42020141041 06/08/2020.

Potential causes of male and female infertility in Qatar

A steady decline in the fertility rate has been observed in Qatar during the past fifty years. Therefore, infertility is considered a national priority in Qatar, a pronatalist society. This review article summarises the potential causes of infertility that are particularly prevalent in the Qatari population. The high rate of consanguinity leading to genetic abnormalities, the high incidence of metabolic disease, environmental contamination due to the rapid urbanization and oil and natural gas extraction procedures are discussed. In addition, the particular lifestyle of the Qatari population and the influence of religion and culture on sexual and reproductive behavior in an Arab/Islamic society are considered. The active response of the state of Qatar in implementing ways to mitigate the effects of these factors to protect fertility are also presented.

LIF regulates CXCL9 in tumor-associated macrophages and prevents CD8+ T cell tumor-infiltration impairing anti-PD1 therapy

Cancer response to immunotherapy depends on the infiltration of CD8⁺ T cells and the presence of tumor-associated macrophages within tumors. Still, little is known about the determinants of these factors. We show that LIF assumes a crucial role in the regulation of CD8⁺ T cell tumor infiltration, while promoting the presence of protumoral tumor-associated macrophages. We observe that the blockade of LIF in tumors expressing high levels of LIF decreases CD206, CD163 and CCL2 and induces CXCL9 expression in tumor-associated macrophages. The blockade of LIF releases the epigenetic silencing of CXCL9 triggering CD8⁺ T cell tumor infiltration. The combination of LIF neutralizing antibodies with the inhibition of the PD1 immune checkpoint promotes tumor regression, immunological memory and an increase in overall survival.

LIF is a pleiotropic cytokine that promotes an immunosuppressive microenvironment and has critical functions in embryonic development. Here, the authors show that LIF regulates CD8⁺ T cell tumor infiltration in cancer by repressing CXCL19 and promoting the presence of protumoral macrophages and thatLIF inhibition, via neutralizing antibodies, promotes T cell infiltration and synergizes with immune checkpoint inhbitors resulting in tumor regression and immunological memory.

Association between leukaemia inhibitory factor gene polymorphism and pregnancy outcomes after assisted reproduction techniques

Certain gene polymorphisms are associated with implantation failure and pregnancy loss. Studies of leukaemia inhibitory factor (LIF) gene polymorphisms are scarce. The LIF single nucleotide polymorphism (SNP) thymine (T)/guanine (G) (rs929271) was studied in women to determine whether an association existed with pregnancy outcomes after intracytoplasmic sperm injection (ICSI); 411 women who underwent ICSI were recruited. DNA was extracted from the peripheral blood, and the LIF gene SNP T/G (rs929271) was genotyped using real-time polymerase chain reaction. Participants were divided into three groups according to their LIF genotype: T/T (n = 168), T/G (n = 202) and G/G (n = 41). All IVF and ICSI procedures were carried out under the same clinical and laboratory conditions. The ICSI cumulative results (from fresh plus frozen cycles) of each genotype group were analysed. The G/G genotype in women was associated with a higher implantation rate (T/T: 15.9%, T/G: 16.2%, G/G: 27.0%; P < 0.05), ongoing pregnancy rate/patient (T/T: 31.5%, T/G: 36.1%, G/G: 53.7%; P < 0.05) and ongoing pregnancy rate/transfer (T/T: 18.5%, T/G: 20.2%, G/G: 36.7%; P < 0.05). LIF SNP T/G (rs929271) seems to be a susceptibility biomarker capable of predicting implantation efficiency and pregnancy outcomes.

Pilot study on molecular quantitation and sequencing of endometrial cytokines gene expression and their effect on the outcome of in vitro fertilization (IVF) cycle

Human trophoblast invasion and differentiation are essential for successful pregnancy outcome. The molecular mechanisms, however, are poorly understood. Interleukin (IL)-11, a cytokine, regulates endometrial epithelial cell adhesion. Leukemia inhibitory factor (LIF) is one of the key cytokines in the embryo implantation regulation. The present study aimed to assess the levels of LIF, IL-11, and IL-11 α receptor gene expression in the endometrium of women undergoing IVF and correlate their levels with the IVF pregnancy outcome. Also, the study aimed to detect any mutation in these three genes among IVF pregnant and non-pregnant women versus control menstrual blood of fertile women. Endometrial tissue biopsies were taken from 15 women undergoing IVF on the day of oocyte retrieval. The quantitative expression of IL-11, IL-11Rα, and LIF genes was assessed by real-time PCR and PCR products were sequenced. Menstrual blood from 10 fertile women was used as control to compare the DNA sequence versus DNA sequence of the studied genes in endometrial biopsies. LH, FSH, and E2 were assessed for enrolled patients by ELISA. Endometrial thickness was also assessed by pelvic ultrasonography. No significant difference was detected between quantitative expression of the three studied genes and pregnancy IVF outcome. Although DNA sequence changes were found in IL-11 and LIF genes of women with negative pregnancy IVF outcome compared to women with positive pregnancy IVF outcome, no DNA sequence changes were detected for IL-11Rα. Other studied parameters (e.g., age, LH, FSH, E2, and endometrial thickness) showed no significant differences or correlation of quantitative expression of the three studied involved genes. Data suggested that there were no significant differences between quantitative expression of IL-11, IL-11Rα, and LIF genes and the IVF pregnancy outcome. The present study may reveal that changes in IL-11 and LIF genes sequence may contribute in pregnancy IVF outcome.

Evaluation of serum concentrations of interleukin (IL)-4, IL-10, and IL-12 during pregnancy in bitches

Complex cytokine networks play an important role in a wide range of pregnancy-related processes. During physiological pregnancy, the balance of T helper lymphocytes Th1 and Th2 is strongly shifted toward Th2, which has a protective role in the feto-maternal interaction. The aim of the present study is to establish the serum concentrations, ranges, and trends of anti-inflammatory interleukin (IL)-4 and IL-10, and inflammatory IL-12A, during three phases of gestation in the bitch (20-30, 31-40, and 41-57 days of gestation). Our results indicate that, in early gestation, IL-4 and -10 serum concentrations are elevated and might depend on progesterone that could act as a potent inhibitor of Th1 responses inducing, conversely, the production of Th2-type cytokines (i.e., IL-10 and IL-4). On the other hand, between 30 and 40 days of gestation, the concentrations of the anti-inflammatory ILs decrease probably because of high concentrations of prolactin, which is endowed with immunostimulatory properties on different immune cell types. In the third phase of gestation (41-57 days), an increase in IL-10 occurs, which might depend on high levels of 17β-estradiol that, during pregnancy, interfere with the ability of dendritic cells to stimulate T lymphocytes, acting as an anti-inflammatory factor. Conversely, the low and persistent concentrations of inflammatory IL-12A, throughout pregnancy, compared with anti-inflammatory ILs, might depend on the characteristic cytokine products of Thl and Th2 cells that are known to be mutually inhibitory. The monitoring of immunological status via the levels of cytokines during pregnancy in the bitch, could represent a diagnostic tool to predict and/or prevent pregnancy abnormality, as demonstrated in women.

[The new function of p53 family and its pathway related proteins in female reproduction]

p53 is an important tumor suppressor gene and one of the key genes in sensing and regulating responses to the environmental stress. Recent study showed that cold winter temperature naturally selected p53 Arg72 in eastern Asian population, suggesting that p53 plays a role in reproduction. It has also been reported that some SNPs of p53, Mdm2(Murine double minute 2), MdmX and Hausp (Herpes virus-associated ubiquitin-specific protease) in p53 pathway are associated with the risk of the women's reproduction disorder. p53 regulates the LIF (leukaemia inhibitory factor) expression level by its DBD domain, and thus contributes to female reproduction by affecting the embryo implantation process. The MDM2, MDMX, and HAUSP proteins regulates the level and activity of p53 protein, which are critical for the appropriate p53 response in the embryo implantation process. The members of p53 family, p63 and p73, also play roles in female reproduction through other pathways. p63 has been implicated as a major regulator of oocyte death following treatment with irradiation and chemotherapeutic drugs, which prevents fetal malformation. p73 regulates the formation of spindle assembly complex(SAC). The dysfunction of SAC results in poor blastocyst quality and defects in kinetochore-microtubule associations, which leads to aneuploidy. This review summarized the function of p53 family and its pathway related proteins in female reproduction, pointed out a new method in improving the success rate in IVF-ET, and provided a new diagnosis idea for unexplained infertile women. It will facilitate personalized strategies in the infertility therapy.

Assessment of leukemia inhibitory factor and glycoprotein 130 expression in endometrium and uterine flushing: a possible diagnostic tool for impaired fertility

Background

Uterine receptivity and implantation are complex processes requiring coordinated expression of molecules by zygote and uterus. Our objective was to evaluate the role of the endometrial expression of leukemia inhibitory factor (LIF) and its glycoprotein 130 (gp130) receptor molecules and their secretion in uterine flushing during the window of implantation in cases of primary unexplained infertility

Case presentation

The study was conducted on 25 infertile women with unexplained infertility for at least two years and 10 normal fertile women as a control group . Endometrial tissue and uterine flushing were obtained. Each tissue specimen was divided into two pieces; one piece was used for histological dating of the endometrium and for immunostaining of progesterone receptors, and the second was used for RNA extraction and PCR assay of LIF and gp130 mRNA expression. Serum estrogen and progesterone were measured for all subjects. LIF mRNA was expressed in the endometrium of all normal fertile women but significantly decreased in infertile women. LIF was not detectable in 88% of infertile women while it was fairly detectable in 12% of them. Gp130 mRNA was hardly detectable in both fertile and infertile women with no difference between them. Infertile women secreted significantly less LIF and gp130 molecules in the uterine flushing compared with normal fertile women.

Conclusions

Expression of LIF mRNA in endometrium could be used as a molecular marker of unexplained infertility. Assessment of secreted LIF and gp130 molecules in uterine flushing could be another useful and safe method for predicting successful implantation as well as for diagnosing and eventually treating women with impaired fertility using recombinant human LIF.

Effect of polymorphisms in the genes for LIF and RBP4 on litter size in two German pig lines

The association of two diallelic polymorphisms in the porcine genes for leukaemia inhibitory factor (LIF) and retinol-binding protein 4 (RBP4) with number of piglets born alive (NBA) in two German pig lines was studied. The investigated single nucleotide polymorphism (SNP) in the porcine LIF gene has been located in the 3'-untranslated region of its third exon, whereas the SNP in the RBP4 gene genotyped in this study is intronic. At the LIF locus the allele frequencies were 0.613 for the A allele and 0.387 for the B allele in German Landrace (GL) and 0.276 for A and 0.724 for B in German Large White (GW). At the RBP4 locus, the allele frequencies were 0.586 for the A allele and 0.414 for the B allele in GL and 0.733 for A and 0.267 for B in GW. There was a significant additive effect of the LIF B allele on NBA in GW over all parities (p <or= 0.05) and a significant positive dominance effect of 0.69 +/- 0.22 (p = 0.002) was observed for first parity on NBA in GL. For RBP4, no association of genotypes and NBA was detected in GW but a significant additive effect of the A allele of 0.24 +/- 0.11 (p = 0.027) and a significant dominance effect of 0.31 +/- 0.13 (p = 0.020) were found in GL over all parities and confirmed through the evaluations by parity.

Association of the leukemia inhibitory factor gene mutation and the antiphospholipid antibodies in the peripheral blood of infertile women

To characterize the impact of the potentially functional mutation--the G to A transition at the position 3400 of the leukemia inhibitory factor (LIF; a pluripotent cytokine that plays a central role in the control of the embryo implantation) gene that leads to the exchange of valine with methionine at codon 64 we evaluated the association of the LIF gene mutation and the levels of antiphospolipid antibodies (aPLs) in the peripheral blood of infertile women (the aPLs examination was part of our routine immunological test during the infertility check-up). Eight infertile mutation-positive women were diagnosed with idiopathic infertility (n=5) and endometriosis (n=3) and their levels of aPLs in serum were compared with 115 infertile women without any LIF gene mutation. Enzyme-linked immunosorbent assay was used for the detection of seven antiphospholipid antibodies; the results were statistically assessed by the Fisher's 2 by 2 exact test to evaluate the association of the LIF gene mutations and aPLs in serum of infertile patients. The presence of aPLs was significantly higher in our study group (100%) than in 30% of aPLs-positives in control infertile patients (p = 0.0035) which indicates that the aPLs are elevated in women with LIF gene mutations.

Cytokine knockouts in reproduction: the use of gene ablation to dissect roles of cytokines in reproductive biology

Cytokines play many diverse and important roles in reproductive biology, and dissecting the complex interactions between these proteins and the different reproductive organs is a difficult task. One approach is to use gene ablation, or 'knockout', to analyse the effect of deletion of a single cytokine on mouse reproductive function. This review summarizes the essential roles of cytokines in reproductive biology that have been revealed by gene knockout studies, including development and regulation of the hypothalamo-pituitary-gondal axis, ovarian folliculogenesis, implantation and immune system modulation during pregnancy. However, successful utilization of this approach must consider the caveats associated with gene ablation studies, e.g. embryonic lethality, systemic effects of cytokine ablation on local reproductive processes and the limited exposure to pathogens in mice housed in laboratory conditions. New sophisticated technology that temporally or spatially regulates gene ablation can overcome some of these limitations. Discoveries on the roles of cytokines in reproductive function uncovered by gene ablation studies can now be applied to improve in vitro fertilization for infertile couples and in the development of contraceptive therapies.

[Physiology of implantation]

This article explains why we have had to come to a central role for innate immunity rather than the threat of maternal rejection of the foetal allograft. We encompass briefly the role of inflammation in implantation, not only for invasion adhesion, but also to prepare future "tolerance". In this context, we envisage the role of TWEAK and complement.

The Th1/Th2 paradigm: still important in pregnancy?

The enunciation of the T helper 1/T helper 2 (Th1/Th2) paradigm in pregnancy has represented a major step forward in our understanding of physiological and pathologic materno-foetal relationship. However, recent developments in studies of the implantation process and in the emergence of the uterine vascular bed and its control by natural killer cells and cytokines suggest that one must go beyond this hitherto useful scheme. In this review, we replace the emergence of the paradigm in its historical context and then emphasises what it does explain and what it no longer account for. A final reappraisal of the paradigm is suggested.

The role of the endometrium and embryo in human implantation

Despite many advances in assisted reproductive technologies (ART), implantation rates are still low. The process of implantation requires a reciprocal interaction between blastocyst and endometrium, culminating in a small window of opportunity during which implantation can occur. This interaction involves the embryo, with its inherent molecular programme of cell growth and differentiation, and the temporal differentiation of endometrial cells to attain uterine receptivity. Implantation itself is governed by an array of endocrine, paracrine and autocrine modulators, of embryonic and maternal origin. Implantation failure is thought to occur as a consequence of impairment of embryo developmental potential and/or impairment of uterine receptivity and the embryo-uterine dialogue. Therefore a better comprehension of implantation, and the relative importance of the factors involved, is warranted. New techniques for monitoring changes in the endometrium and/or the embryo at the level of gene regulation and protein expression may lead to the identification of better markers for implantation. Moreover, the use of predictive sets of markers may prove to be more reliable than a single marker. Continuing refinements to ART protocols, such as optimizing ovarian stimulation regimens, the timing of human chorionic gonadotrophin injection, or the timing of embryo transfer, should help to increase implantation rates further.

Impact of high body mass index on endometrial morphology and function in the peri-implantation period in women with recurrent miscarriage

There is evidence that women with a high body mass index may have a higher risk of miscarriage. It is not known if this is due to an endometrial or embryo defect. The aim of this retrospective study was to examine markers of endometrial function in overweight and obese women with recurrent unexplained miscarriage. A total of 136 women were included in the study and classified according to their body mass index (BMI) into two groups, normal BMI (< 25 kg/m(2), n = 70) and high BMI (> or = 25 kg/m(2), n = 66). Endometrial morphology was examined in all patients. A subgroup of 28 patients was examined for endometrial oestrogen and progesterone receptors in different components of the endometrium, and in a further subgroup of 28 patients, endometrial glandular leukaemia inhibitory factor and leukocyte populations were examined. A modest increase in the BMI (30.4 +/- 0.71 kg/m(2)) does not have a significant impact on endometrial steroid receptors, leukocyte populations or endometrial morphology. However, there was a significant negative correlation between endometrial glandular leukaemia inhibitory factor concentrations and the BMI (r = -0.4, P = 0.02), warranting further investigation in prospective studies that include patients with higher BMI levels.

Role of the leukemia-inhibitory factor gene mutations in infertile women: the embryo-endometrial cytokine cross talk during implantation--a delicate homeostatic equilibrium

Locally secreted cytokines of both the embryonic and the endometrial origin control the implantation process. The defects in their signaling that lead to unfavorable environment within the uterus may cause embryo implantation failure. The leukemia inhibitory factor (LIF), interleukin-11 (IL-11) as well as IL-12/IL-15/IL-18 system are regarded to be important signaling vectors. LIF plays an essential role in the preimplantation embryo development and the blastocyst implantation and its gene mutations in women contribute to the implantation failure and subsequent infertility. IL-11 signaling has been shown to be required for the uterine decidualization response as well as for the hatching and attachment of blastocysts. The IL-12/IL-15/IL-18 system interacts with endometrial leukocytes, particularly with NK cells, and influences directly the local angiogenesis and tissue remodeling. Differences in the levels of endometrial leukocytic subpopulations and in the patterns of intra-uterine cytokine concentrations that are observed between fertile and infertile women contribute to infertility probably by affecting the embryonic maternal dialogue during the implantation and early placentation period. Focusing on this cross talk promises to open new era in assisted reproduction techniques that will be based on diagnostics of missing signaling molecules and impairments of uterine receptivity as well as on therapeutic applications of individualized embryo culture and transfer media.