Does the Immune System Induce Labor? Lessons from Preterm Deliveries in Women with Autoimmune Diseases

17-α Hydroxyprogesterone Caproate Immunology, a Special Focus on Preterm Labor, Preeclampsia, and COVID-19

17-α hydroxyprogesterone caproate (17-OHPC) could alter the immune response and inflammation, specifically affecting the risk of preterm labor and preeclampsia. However, the exact immune and inflammatory effects of 17-OHPC remain hard to be identified. The current literature on 17-OHPC immune effects is limited and more research is needed to identify these mechanistic pathways. Further, coronavirus disease 2019 (COVID-19) infection in pregnancy involves heightened immune response, widespread inflammation and high rates of preterm labor and preeclampsia. Since the pathogenesis of preterm labor, preeclampsia and COVID-19 involves inflammation and altered immune response, it is important to explore the possible immune effects of 17-OHPC in pregnant women with COVID-19. This commentary article will explain the immune effects of 17-OHPC and their implications in preterm labor, preeclampsia and COVID-19.

Expected advances in human fertility treatments and their likely translational consequences

BACKGROUND

Due to rapid research progress in reproductive biology and reproductive clinical endocrinology, many human infertility treatments are close to potential breakthroughs and translational applications. We here review current barriers, where such breakthroughs will likely come from, what they will entail, and their potential clinical applications.

MAIN TEXT

The radical nature of change will primarily benefit older women, reduce fertility treatment costs and thereby expand access to treatment. A still widely overlooked prerequisite for implantation and normal pregnancy maintenance is timely development of maternal immunological tolerance toward an implanting paternal semi-allograft, if malfunctioning associated with implantation failure and pregnancy loss, while premature termination of tolerance appears associated with premature labor, pre-eclampsia/eclampsia and gestoses of pregnancy. Common denominators between pregnancy and invasive malignancies have again been attracting attention, suggesting that, like in malignant tumors, degrees of embryo aneuploidy may affect invasiveness and ability to "disarm" the immune system's innate response against implanting embryos. Linking tolerance to implantation, we offer evidence that the so-called "implantation window" is likely immunological rather than hormonally defined.

CONCLUSIONS

Because many here outlined treatment changes will disproportionally benefit older women, they will exert a pronounced effect on society, as increasing numbers of women at grandparental ages will become mothers.

Whole-transcriptome analysis delineates the human placenta gene network and its associations with fetal growth

BACKGROUND

The placenta is the principal organ regulating intrauterine growth and development, performing critical functions on behalf of the developing fetus. The delineation of functional networks and pathways driving placental processes has the potential to provide key insight into intrauterine perturbations that result in adverse birth as well as later life health outcomes.

RESULTS

We generated the transcriptome-wide profile of 200 term human placenta using the Illumina HiSeq 2500 platform and characterized the functional placental gene network using weighted gene coexpression network analysis (WGCNA). We identified 17 placental coexpression network modules that were dominated by functional processes including growth, organ development, gas exchange and immune response. Five network modules, enriched for processes including cellular respiration, amino acid transport, hormone signaling, histone modifications and gene expression, were associated with birth weight; hub genes of all five modules (CREB3, DDX3X, DNAJC14, GRHL1 and C21orf91) were significantly associated with fetal growth restriction, and one hub gene (CREB3) was additionally associated with fetal overgrowth.

CONCLUSIONS

In this largest RNA-Seq based transcriptome-wide profiling study of human term placenta conducted to date, we delineated a placental gene network with functional relevance to fetal growth using a network-based approach with superior scale reduction capacity. Our study findings not only implicate potential molecular mechanisms underlying fetal growth but also provide a reference placenta gene network to inform future studies investigating placental dysfunction as a route to future disease endpoints.

Redirecting reproductive immunology research toward pregnancy as a period of temporary immune tolerance

Referring to two recent publications, we here propose that clinical reproductive immunology has for decades stagnated because reproductive medicine, including assisted reproduction (AR), has failed to accept embryo implantation as an immune system-driven process, dependent on establishment of maternal tolerance toward the implanting fetal semi-allograft (and complete allograft in cases of oocyte donation). Pregnancy represents a biologically unique period of temporary (to the period of gestation restricted) tolerance, otherwise only known in association with parasitic infections. Rather than investigating the immune pathways necessary to induce this rather unique state of tolerance toward the rapidly growing parasitic antigen load of the fetus, the field, instead, concentrated on irrelevant secondary immune phenomena (i.e., "immunological noise"). It, therefore, does not surprise that interesting recent research, offering new potential insights into maternal tolerance during pregnancy, was mostly published outside of the field of reproductive medicine. This research offers evidence for existence of inducible maternal tolerance pathways with the ability of improving maternal fecundity and, potentially, reducing such late pregnancy complications as premature labor and preeclampsia/eclampsia due to premature abatement of maternal tolerance. Increasing evidence also suggests that tolerance-inducing immune pathways are similar in successful pregnancy, successful organ transplantation and, likely also in the tolerance of "self" (i.e., prevention of autoimmunity). Identifying and isolating these pathways, therefore, may greatly benefit all three of these clinical areas, and research in reproductive immunology should be accordingly redirected.

Some aspects of interactivity between endocrine and immune systems required for successful reproduction

BACKGROUND

In successful reproduction, endocrine and immune systems closely interact. We here attempt to further elucidate the relationship between androgen levels, systemic activation of the immune system and reproductive success in infertile women, utilizing 2 distinct infertile patient cohorts.

METHODS

In Group 1, we investigated 322 women (ages 38.6+/-5.4 years) at initial presentation; in Group 2 125 women undergoing in vitro fertilization (169 IVF cycles, ages 38.9+/-5.5 years). In Group 1, we assessed androgens and an immune panel, previously demonstrated to discriminate between activated quiescent immune systems; in Group 2, utilizing the same immune panel, we investigated whether immune system activation relates to embryo quality in IVF cycles.

RESULTS

No individual immune test within the immune panel was associated with androgen levels. The total/free testosterone ratio (TT/FT) was, however, significantly associated with presence of gammopathies (in IgG, IgM, IgA, IgE; P=0.026). Surprisingly, immune system activation was associated with significantly improved embryo quality (P=0.008), a finding persistent after adjustment for age and repeat IVF cycles (P=0.006).

CONCLUSIONS

Association of immune system activation with improved embryo quality concurs with previously reported immune activation in association with normal functional ovarian reserve (FOR) and normal androgen levels, while, counter intuitively, hypoandrogenism and low FOR are associated with lack of immune system activation. Mild immune system activation, therefore, likely appears essential for establishment of pregnancy, and may be regulated by androgens.

Maternal autoimmunity and adverse pregnancy outcomes

Some of the most dangerous and costly complications of human pregnancy, including premature labor and preeclampsia/eclampsia, have remained unexplained. While not noted by the authors of a recently published study of three distinct groups of patients with thyroid disease, their data may offer new insights into the interplay between thyroid autoimmune disease, indeed possibly autoimmunity in general, and human pregnancy. This editorial discusses a report of 223,512 pregnancies (2002-2008) from a retrospective U.S. cohort, the Consortium of Safe Labor, reported by Männistö et al. from the Epidemiology Branch, Division of Epidemiology, Statistics and Prevention Research, Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health, Rockville, Maryland in the July 2013 issue of The Journal of Clinical Endocrinology and Metabolism. Reading between the lines of this publication offers potential insights into the etiologies of preeclampsia/eclampsia and of term as well as premature labor. Moreover, this study, unintentionally, may also offer insights into currently still only poorly understood immune dysfunction that links autoimmunity with adverse pregnancy outcomes.

Endocrine autoimmune diseases and female infertility

An increasing body of evidence suggests that immune-mediated processes affect female reproductive success at multiple levels. Crosstalk between endocrine and immune systems regulates a large number of biological processes that affect target tissues, and this crosstalk involves gene expression, cytokine and/or lymphokine release and hormone action. In addition, endocrine-immune interactions have a major role in the implantation process of the fetal (paternally derived) semi-allograft, which requires a reprogramming process of the maternal immune system from rejection to temporary tolerance for the length of gestation. Usually, the female immune system is supportive of all of these processes and, therefore, facilitates reproductive success. Abnormalities of the female immune system, including autoimmunity, potentially interfere at multiple levels. The relevance of the immune system to female infertility is increasingly recognized by investigators, but clinically is often not adequately considered and is, therefore, underestimated. This Review summarizes the effect of individual autoimmune endocrine diseases on female fertility, and points towards selected developments expected in the near future.

Multiple pregnancy, short cervix, part-time worker, steroid use, low educational level and male fetus are risk factors for preterm birth in Japan: a multicenter, prospective study

AIM

To examine the relationship between preterm birth and socioeconomic factors, past history, cervical length, cervical interleukin-8, bacterial vaginosis, underlying diseases, use of medication, employment status, sex of the fetus and multiple pregnancy.

METHODS

In a multicenter, prospective, observational study, 1810 Japanese women registering their future delivery were enrolled at 8⁺⁰ to 12⁺⁶ weeks of gestation. Data on cervical length and delivery were obtained from 1365 pregnant women. Multivariate logistic regression analysis was performed.

RESULTS

Short cervical length, steroid use, multiple pregnancy and male fetus were risk factors for preterm birth before 34 weeks of gestation. Multiple pregnancy, low educational level, short cervical length and part-timer were risk factors for preterm birth before 37 weeks of gestation.

CONCLUSION

Multiple pregnancy and cervical shortening at 20-24 weeks of gestation was a stronger risk factor for preterm birth. Any pregnant woman being part-time employee or low educational level, having a male fetus and requiring steroid treatment should be watched for the development of preterm birth.

Evidence for a role for the adaptive immune response in human term parturition

PROBLEM

Spontaneous labor at term involves leukocyte recruitment and infiltration into the choriodecidua; yet, characterization of these leukocytes and their immunological mediators is incomplete. The purpose of this study was to characterize the immunophenotype of choriodecidual leukocytes as well as the expression of inflammatory mediators in human spontaneous parturition at term.

METHOD OF STUDY

Choriodecidual leukocytes were analyzed by FACS, immunohistochemistry, and RT-PCR in three different groups: (i) preterm gestation delivered for medical indications without labor; (ii) term pregnancy without labor; and (iii) term pregnancy after spontaneous labor.

RESULTS

Two T-cell subsets of memory-like T cells (CD3(+) CD4(+) CD45RO(+) and CD3(+) CD4(-) CD8(-) CD45RO(+) cells) were identified in the choriodecidua of women who had spontaneous labor. Evidence for an extensive immune signaling network composed of chemokines (CXCL8 and CXCL10), chemokine receptors (CXCR1-3), cytokines (IL-1β and TNF-α), cell adhesion molecules, and MMP-9 was identified in these cells during spontaneous labor at term.

CONCLUSIONS

The influx of memory-like T cells in the choriodecidua and the evidence that they are active by producing chemokines and cytokines, and expressing chemokine receptors, cell adhesion molecules, and a matrix-degrading enzyme provides support for the participation of the adaptive immune system in the mechanisms of spontaneous parturition at term.

Mechanisms and pathophysiology of autoimmune disease

The first textbook on autoimmunity was published by Ian Mackay and McFarland Burnett in 1963. It was the first attempt to summarize existing knowledge on human autoimmunity. Since that time, there have been tens of thousands of experimental papers and numerous textbooks that focus on the diagnosis and treatment of human autoimmunity. There have been at least as many, if not more, directed at similar issues in animal models. Enormous strides have been made not only in diagnosis, but also in the pathophysiology and especially in treatment. We have gone from the era of simple HLA typing to deep sequencing and, more recently, epigenetic analysis. We have gone from the era of white blood cell differentials to detailed lymphoid phenotyping. We have gone from the era of simple antinuclear antibodies to detailed and sophisticated immunodiagnosis with recombinant autoantigens and disease-specific epitopes. We have gone from the era of using only corticosteroids to selective biologic agents. Diseases that were previously considered idiopathic are now very much understood as autoimmune. We are in the era of autoinflammatory reactions and the concept of both innate versus adaptive immunity in mediating immunopathology. In this edition of Clinical Reviews in Allergy and Immunology, we focus on key and cutting-edge issues in the pathophysiology of autoimmunity. The issues are very much oriented and driven by hypothesis, i.e., a prediction of events expected to occur based on observations. It is not meant to be a complete summary of potential mechanisms of autoimmunity, but rather an attempt to accelerate discussion and better understanding. The primary goal is obviously to help our patients with autoimmune disease.

Cutting edge assessment of the impact of autoimmunity on female reproductive success

There, likely, is no more controversial issue in reproductive medicine than the effects of autoimmunity on female reproductive success. Published studies are, therefore, often biased. We performed PubMed, Google Scholar and Medline searches for the years 2000-2010 under various key words and phrases, referring to effects of autoimmunity/autoimmune diseases on pregnancy/pregnancy outcomes/pregnancy rates/reproduction/reproductive outcomes/fertility/infertility/fertility treatments/infertility treatments, and a number of similar terms. Reference lists of selected manuscripts were evaluated for additional, potential references. All selected manuscripts were reviewed by at least one author (N.G.). Opinions were reached based on preferential review of only selected studies, which offered data, primarily developed in pursuit of unrelated scientific questions. Data from various medical fields point, surprisingly effectively, toward significant impacts of autoimmunity on female reproductive success. Autoimmunity not only increases miscarriage risks but also reduces female fecundity and infertility treatment success. A, likely, reason why differences of opinion have persisted is that effects are primarily observed in genetically predisposed women, with specific fragile X mental retardation 1 (FMR1) genotypes. This discovery coincides with recently increasing appreciation of the importance of the long arm of the X chromosome (Xq) in control of functional ovarian reserve (reflective of female fertility) and autoimmunity, with FMR1at Xq27.3, located at cross roads of both. Autoimmune effects on female reproductive success deserve recognition. Further investigations must not ignore patient stratification, based on ovarian FMR1 genotypes. Genetic definition of high-risk patients should lead to development of successful therapeutic interventions.

Reproductive immunology: current status and future directions (part I)

Extensive research work over the past couple of decades has indicated a series of intricate relations between immune and reproductive systems. A range of reproductive immunology topics including the roles of adoptive and innate immunity in infertility and pregnancy, the immune system's role in induction of labor and preterm delivery, and immuno-modulatory effects of the female sex hormones will be discussed in this and the next issue of the Journal. The implications of this research on the development of novel therapeutic approaches are also addressed.

The impact of fetal gender on prematurity in dichorionic twin gestations after in vitro fertilization

BACKGROUND

Impact of fetal gender on prematurity has been primarily investigated in singleton pregnancies. In an attempt to understand better how fetal gender may affect gestational length in twin gestations after in vitro fertilization, same-sex twins and opposite twins were compared for pregnancy duration.

METHODS

This study evaluated 113 women at ages 20 to 39 years with consecutive dichorionic-diamniotic twin gestations after assisted reproduction. All pregnancies were results of fresh in vitro fertilization (IVF) cycles with use of autologous oocytes and sperm and were delivered at up to 37 weeks of gestation at a University-based high-risk, maternal-fetal medicine unit.

RESULTS

Both groups did not differ in baseline characteristics, such as maternal ages, indications for fertility treatments, number of previous IVF attempts, body mass index and parity. Opposite sex- twins, however, presented with significantly shorter gestational age at birth (32.9 +/- 3.4 weeks) than same-sex twins (34.3 +/- 2.5 weeks), (p < 0.05). Younger maternal age was also associated with shorter pregnancy duration (p < 0.05).

CONCLUSIONS

Fetal gender mix serves as risk factor for more significant prematurity in dichorionic-diamniotic twins after assisted reproduction with opposite sex twins at higher risk than same sex-twins.