Increased levels of macrophage migration inhibitory factor (MIF) in preeclampsia

Systemic inflammatory regulators and preeclampsia: a two-sample bidirectional Mendelian randomization study

Background

Systemic inflammatory regulators have been associated with preeclampsia (PE) during pregnancy; however, there is inconsistent evidence from animal models and observational results.

Methods

Using summary data from genome-wide association studies (GWASs), we performed a bidirectional Mendelian randomization (MR) analysis of two samples of systemic inflammatory regulators (n = 8,186) and PE (n = 267,242) individuals of European ancestry. As our primary analysis, we used the random-effects inverse-variance weighted (IVW) approach. Sensitivity and pleiotropy analyses were conducted using the MR-Egger method, weighted median, MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO), and Cochran's Q test.

Results

The results indicate that there is a correlation between a higher circulating level of tumor necrosis factor alpha (TNF-α) and interleukin-9 (IL-9) and an increased risk of PE (odds ratio [OR] = 1.32, 95% confidence interval [CI] = 1.09-1.60, p = 0.004 and OR = 1.28, 95% CI: 1.02-1.62, p = 0.033, respectively). Conversely, lower levels of stem cell growth factor beta (SCGF-β) (OR = 0.89, 95% CI: 0.80-0.99, p = 0.027) and interleukin-5 (IL-5) (OR = 0.80, 95% CI: 0.65-0.98, p = 0.030) are linked to an increased risk of PE. The macrophage migration inhibitory factor (MIF) is the downstream inflammatory regulator of PE, according to reverse magnetic resonance imaging studies.

Conclusion

Our study suggests that SCGF-β, IL-5, IL-9, and TNF-α causally affect the PE risk, while PE is causally associated with MIF. Further studies are needed to validate these biomarkers in managing PE.

Regulatory role of human endometrial gland secretome on macrophage differentiation

The human endometrial gland plays a vital role in maternal immune tolerance and placental development. Decidual macrophages are the major phagocytic cells that regulate tissue remodeling during pregnancy. This study examines the regulatory effect of endometrial gland secretome on macrophage polarization and functions using endometrial organoid. We demonstrated that endometrial organoids treated with hormones mimicking the environment of the secretory phase/early pregnancy polarize macrophages to acquire a decidua-like macrophage phenotype, including higher expressions of decidual macrophage markers, reduced phagocytic capacity and altered cytokine secretion. The results indicated that endometrial gland secretomes are critical for maintaining macrophage homeostasis at the maternal-fetal interface.

Circulating inflammatory cytokines and hypertensive disorders of pregnancy: a two-sample Mendelian randomization study

Background

Hypertensive disorders of pregnancy (HDP) pose a significant risk to maternal and fetal well-being; however, the etiology and pathogenesis of HDP remain ambiguous. It is now widely acknowledged that inflammatory response and the immune system are closely related to HDP. Previous research has identified several inflammatory cytokines are associated with HDP. This study applied Mendelian randomization (MR) analysis to further assess causality.

Methods

Patients with HDP who participated in the MR analysis presented with four types of HDP: pre-eclampsia or eclampsia (PE); gestational hypertension (GH); pre-existing hypertension complicating pregnancy, childbirth and the puerperium (EH); and pre-eclampsia or poor fetal growth (PF). A two-sample MR analysis was used to analyze the data in the study. The causal relationship between exposure and outcome was analyzed with inverse variance weighting (IVW), MR Egger, weighted median, weighted mode, and simple mode methods, where IVW was the primary method employed.

Results

Our MR analysis demonstrated a reliable causative effect of Interleukin-9 (IL-9) and macrophage migration inhibitory factor (MIF) on reducing HDP risk, while macrophage inflammatory protein 1-beta (MIP1b), Interleukin-13 (IL-13), and Interleukin-16 (IL-16) were associated with promoting HDP risk.

Conclusions

This study demonstrated that IL-9, MIF, MIP1b, IL-13, and IL-16 may be cytokines associated with the etiology of HDP, and that a number of inflammatory cytokines are probably involved in the progression of HDP. Additionally, our study revealed that these inflammatory cytokines have causal associations with HDP and may likely be potential therapeutic targets for HDP.

MIF Increases sFLT1 Expression in Early Uncomplicated Pregnancy and Preeclampsia

Insufficient immune tolerance during pregnancy is associated with pathological conditions such as preeclampsia (PE). Soluble fms-like tyrosine kinase-1 (sFLT1), which exerts a role in the late stage of PE, has shown its beneficial anti-inflammatory effects in inflammation-associated diseases. Macrophage migration inhibitory factor (MIF) was reported to upregulate sFLT1 production in experimental congenital diaphragmatic hernia. However, the placental sFLT1 expression in early uncomplicated pregnancy and whether MIF can regulate sFLT1 expression in uncomplicated and preeclamptic pregnancy are unclear. We collected first-trimester placentas and term placentas from uncomplicated and preeclamptic pregnancies to investigate sFLT1 and MIF expression in vivo. Primary cytotrophoblasts (CTBs) and a human trophoblast cell line (Bewo) were used to study the regulation of MIF on sFLT1 expression in vitro. In placentas from first-trimester pregnancy, we observed a high expression of sFLT1, specifically in extravillous trophoblasts (EVTs) and syncytiotrophoblast (STB) cells. MIF mRNA levels strongly correlated with sFLT1 expression in term placentas from preeclamptic pregnancies. In in vitro experiments, sFLT1 and MIF levels increased significantly in CTBs during their differentiation to EVTs and STBs, and MIF inhibitor (ISO-1) significantly reduced sFLT1 expression in a dose-dependent manner during this process. sFLT1 showed significant upregulation with increasing doses of MIF in Bewo cells. Our results show that sFLT1 is highly expressed at the maternal-fetal interface during early pregnancy and that MIF can increase sFLT1 expression in early uncomplicated pregnancy and PE, which suggests that sFLT1 plays an essential role in the modulation of inflammation in pregnancy.

Anti-Mullerian Hormone and Macrophage Migration Inhibitory Factor Determine the Reproductive Health of Ladakhi Women Residing at 3,500 m

Shaw, Snigdha, Himashree Gidugu, Gopinath Bhaumik, Maramreddy Prasanna Kumar Reddy, Usha Panjwani, and Dishari Ghosh. Anti-Mullerian hormone and macrophage migration inhibitory factor determine the reproductive health of Ladakhi women residing at 3,500 m. High Alt Med Biol. 00:000-000, 2021. Background: Reproductive health of Ladakhi high-altitude (HA) native females was investigated for the first time in this study. Available literature suggest that, female reproductive cycle and hormonal profile varies in different HA populations due to heterogeneity. Although these studies illustrate some progress on the role of HA hypoxia, it still leaves scope for evaluation of the remaining mechanisms involved in the maintenance of reproductive health in this contemporary population. Materials and Methods: Menstrual details, phasic variations in circulatory steroid hormones, and gonadotropins along with oxytocin in sea level (SL) and HA (∼3,500 m) native females of India were assessed. Moreover, ovarian reserve marker anti-Mullerian hormone (AMH) and proinflammatory cytokine macrophage migration inhibitory factor (MIF) were measured. Results: A difference in Ladakhi women was registered compared to SL, regarding luteinizing hormone (LH) (2.6 mIU/ml vs. 4.4 mIU/ml, p < 0.05) and progesterone (P) (4.1 ng/ml vs. 9.4 ng/ml, p < 0.05) levels in their luteal phase. Reduced LH might contribute to poor development of the ovarian corpus luteum, subsequently diminish P level. Decreased AMH level in three age groups: 21-30 years (1.4 ng/ml vs. 3.2 ng/ml, p < 0.01), 31-40 years (0.6 ng/ml vs. 2.1 ng/ml, p < 0.01), and >40 years (0.4 ng/ml vs. 1.7 ng/ml, p < 0.01) of Ladakhi women were recorded than their SL counterpart. Elevated oxytocin (83.5 ng/ml vs. 76.3 ng/ml, p < 0.05) and MIF levels (70.2 ng/ml vs. 49.7 ng/ml, p < 0.01) along with low P and AMH levels delineated the reason for recorded early menopause (43.9 years), shorter reproductive span (∼29 years), and history of miscarriage in HA dwellers compared to SL. Conclusion: Therefore, the findings insinuated that the response of the reproductive system to hypoxia in Ladakhi women differs from SL women, and the adaptive response in these women might be in favor of their reproductive health.

Macrophage migration inhibitory factor in human early pregnancy events and association with placental pathologies

Macrophage migration inhibitory factor (MIF) is a versatile cytokine acting as an important regulator of innate and adaptive immunity and implicated in many physiological and pathological processes. It is abundantly expressed at the feto-maternal interface and proposed to have a role in establishing and maintaining a healthy pregnancy. This review presents the current literature data regarding the MIF role in early pregnancy events and its association with some of the placental pathological conditions, including infection, preeclampsia, gestational diabetes mellitus and choriocarcinoma. General information regarding MIF structure and function is followed by an overview of its expression in reproductive tissues and in pregnancy. Futher, we discuss MIF's involvement in the survival of decidual stromal cells, placenta of the first trimester of pregnancy, and in trophoblast cell functions studied in vitro. Current findings associating this cytokine to placental infection, preeclampsia, gestational diabetes mellitus and choriocarcinoma are presented in the final part.

Role of the Macrophage Migration Inhibitory Factor in the Pathophysiology of Pre-Eclampsia

Proinflammatory cytokines are produced in pregnancy in response to the invading pathogens and/or nonmicrobial causes such as damage-associated molecules and embryonic semi-allogenic antigens. While inflammation is essential for a successful pregnancy, an excessive inflammatory response is implicated in several pathologies including pre-eclampsia (PE). This review focuses on the proinflammatory cytokine macrophage migration inhibitory factor (MIF), a critical regulator of the innate immune response and a major player of processes allowing normal placental development. PE is a severe pregnancy-related syndrome characterized by exaggerated inflammatory response and generalized endothelial damage. In some cases, usually of early onset, it originates from a maldevelopment of the placenta, and is associated with intrauterine growth restriction (IUGR) (placental PE). In other cases, usually of late onset, pre-pregnancy maternal diseases represent risk factors for the development of the disease (maternal PE). Available data suggest that low MIF production in early pregnancy could contribute to the abnormal placentation. The resulting placental hypoxia in later pregnancy could produce high release of MIF in maternal serum typical of placental PE. More studies are needed to understand the role of MIF, if any, in maternal PE.

Abnormal uterine inflammation in obstetric syndromes: molecular insights into the role of chemokine decoy receptor D6 and inflammasome NLRP3

The adaptation of the uterine environment into a favorable immunological and inflammatory milieu is a physiological process needed in normal pregnancy. A uterine hyperinflammatory state, whether idiopathic or secondary to hormonal or organic uterine disorders (polycystic ovary syndromes, endometriosis/adenomyosis and fibroids), negatively influences the interactions between decidua and trophoblast, early in gestation, and between chorion and decidua later in pregnancy. Abnormal activation of uterine inflammatory pathways not only contributes to the pathogenesis of the obstetric syndromes, i.e. recurrent pregnancy loss (RPL), pre-term delivery (PTD) and pre-eclampsia (PE), but also to correlates with severity. In this review, we summarize recent advances in the knowledge of uterine molecular mechanisms of inflammatory modulation in normal pregnancy and obstetric syndromes (RPL, PTD and PE). In particular, we focus on two regulators of uterine/placental inflammation: the NLRP3 inflammasome and the chemokines decoy receptor D6. We performed comprehensive review of the literature in PubMed and Google Scholar databases from 1994 to 2018. The available evidence suggests that: (i) the expression of inflammasome NLRP3 is increased in the endometrium of women with unexplained RPL, in the chorioamniotic membranes of women with PTL and in the placenta of women with PE; (ii) there is a role for abnormal expression and function of D6 decoy receptor at the feto-maternal interface in cases of RPL and PTD and (iii) the function of placental D6 decoy receptor is impaired in PE. A wider comprehension of the inflammatory molecular mechanisms involved in the pathogenesis of the obstetric syndromes might lead to the identification of new potential therapeutic targets.

The emerging role of red blood cells in cytokine signalling and modulating immune cells

For many years red blood cells have been described as inert bystanders rather than participants in intercellular signalling, immune function, and inflammatory processes. However, studies are now reporting that red blood cells from healthy individuals regulate immune cell activity and maturation, and red blood cells from disease cohorts are dysfunctional. These cells have now been shown to bind more than 50 cytokines and have been described as a sink for these molecules, and the loss of this activity has been correlated with disease progression. In this review, we summarise what is currently understood about the role of red blood cells in cytokine signalling and in modulating the activity of immune cells. We also discuss the implications of these findings for transfusion medicine and in furthering our understanding of anaemia of chronic inflammation. By bringing these disparate units of work together, we aim to shine a light on an area that requires significantly more investigation.

Role of Macrophages in Pregnancy and Related Complications

Macrophages (MФs) are the leukocytes produced from differentiation of monocytes and are located in almost all tissues of human body. They are involved in various processes, such as phagocytosis, innate and adaptive immunity, proinflammatory (M1) and anti-inflammatory (M2) activity, depending on the tissue microenvironment. They play a crucial role in pregnancy, and their dysfunction or alteration of polarity is involved in pregnancy disorders, like preeclampsia, recurrent spontaneous abortion, infertility, intrauterine growth restriction, and preterm labor. About 50-60% of decidual leukocytes are natural killer (NK) cells followed by MФs (the second largest population). MФs are actively involved in trophoblast invasion, tissue and vascular remodeling during early pregnancy, besides their role as major antigen-presenting cells in the decidua. These cells have different phenotypes and polarities in different stages of pregnancy. They have also been observed to enhance tumor growth by their anti-inflammatory activity (M2 type) and prevent immunogenic rejection. Targeted alteration of polarity (M1-M2 or vice versa) could be a major focus in the future treatment of pregnancy complications. This review is focused on the role of MФs in pregnancy, their involvement in pregnancy disorders, and decidual MФs as possible therapeutic targets for the treatment of pregnancy complications.

Recruitment of MAIT Cells to the Intervillous Space of the Placenta by Placenta-Derived Chemokines

The intervillous space of the placenta is a part of the fetal-maternal interface, where maternal blood enters to provide nutrients and gas exchange. Little is known about the maternal immune cells at this site, which are in direct contact with fetal tissues. We have characterized the T cell composition and chemokine profile in paired intervillous and peripheral blood samples from healthy mothers giving birth following term pregnancies. Mucosal-associated invariant T (MAIT) cells and effector memory (EM) T cells were enriched in the intervillous blood compared to peripheral blood, suggesting that MAIT cells and other EM T cells home to the placenta during pregnancy. Furthermore, pregnant women had lower proportions of peripheral blood MAIT cells compared to non-pregnant women. The levels of several chemokines were significantly higher in intervillous compared to peripheral blood, including macrophage migration inhibitory factor (MIF), CXCL10, and CCL25, whereas CCL21, CCL27 and CXCL12 were lower. Migration assays showed that MAIT cells and EM T cells migrated toward conditioned medium from placental explants. A multivariate factor analysis indicated that high levels of MIF and CCL25 were associated with high proportions of MAIT cells in intervillous blood. Blocking of MIF or a combination of MIF, CCL25, and CCL20 in migration assays inhibited MAIT cell migration toward placenta conditioned medium. Finally, MAIT cells showed migratory capacities toward recombinant MIF. Together, these findings indicate that term placental tissues attract MAIT cells, and that this effect is at least partly mediated by MIF.

Maternal and umbilical cord blood level of macrophage migration inhibitory factor and insulin like growth factor in Sudanese women with preeclampsia

Preeclampsia is a health concern and it is the main cause of maternal and perinatal mortality. The macrophage migration inhibitory factor (MIF) and insulin-like growth factor-I (IGF-I) are factors associated with preeclampsia. A case-control (45 women in each arm) study was conducted at Saad Abualila Maternity Hospital (Khartoum, Sudan). The cases were of women who had preeclampsia, and the controls were healthy pregnant women. The clinical and obstetrical characteristics were gathered using a questionnaire and MIF and IGF-I levels were measured by ELISA. The cases and the controls (45 in each arm) were matched in their basic data. In comparison with the healthy controls, while the median (interquartile range) of the maternal MIF [8.221 (7.334-8.820) vs. 3.717 (2.385-4.883) ng/mL, p < .001] was significantly higher, the levels of the maternal IGF-1 [1.250 (0.670-1.980) vs. 1.939 (1.056-2.752), ng/mL, p < .001] were significantly lower in the women with preeclampsia. There was no significant difference in the cord levels of both the MIF and IGF-1 between the cases and controls. In linear regression, preeclampsia was the only factor that was significantly associated with the log of the maternal MIF (-0.338 ng/mL, p < .001), IGF-1 (0.293 ng/mL, p = .005) and cord MIF (-0.340 ng/mL, p < .001) levels. Impact statement What is already known on this subject? Macrophage migration inhibitory factor (MIF) has a pivotal role in pro-inflammatory processes during pregnancy/labour and its levels have been correlated with preeclampsia. Insulin like factors are produced in the liver under the stimulation of the growth hormones; they stimulate cell differentiation proliferations. IGF-I may be implicated in the pathogenesis of the adverse effects of preeclampsia (mainly the birth weight). What do the results of this study add? The current study showed a significantly higher level of MIF and lower level IGF-1 in the women with preeclampsia. Thus, both MIF and IGF-1 might have a role in the pathogeneses of preeclampsia. What are the implications of these findings for clinical practice and/or further research? MIF and IGF might be used as reliable markers to detect preeclampsia. These markers might be used as preventive or therapeutic elements for preeclampsia.

Maternal plasma concentrations of macrophage migration inhibitory factor at first trimester as a predictive biomarker of preterm delivery in Chinese women

BACKGROUND

Infection and/or inflammation have been proposed play role in the preterm delivery (PTD) pathogenesis. Macrophage migration inhibitory factor(MIF), a mediator of innate immunity and inflammation, is induced in various infections, including those that occur during pregnancy. We assessed the relation between maternal early pregnancy plasma concentrations of MIF and PTD.

METHODS

Women were recruited before 14 weeks gestation and were followed up until delivery. Maternal plasma concentrations of MIF, C-reactive protein (CRP) and interleukin 6 (IL-6) at first visit were measured by competitive immunoassay. The diagnosis of PTD was made using American College of Obstetricians and Gynaecologists (ACOG) guidelines. Logistic regression procedures were used to calculate adjusted odds ratio (OR) and 95% confidence intervals (95%CI).

RESULTS

In the study period, 596 participants were included. The median plasma concentration of MIF was significantly higher in women in whom PTD later developed compared with those delivering at term (P < 0.001). For each 1 ng/ml increase of plasma concentration of MIF, the unadjusted and adjusted risk of PTD would be increased by 12% (with the OR of 1.12 [95% CI 1.07-1.17], P < 0.001) and 7% (1.07 [1.02-1.15], P = 0.002), respectively. Stratified analyses indicated that increased MIF was associated with an increased risk of spontaneous delivery (OR = 1.16, 95%CI: 1.07-1.24; P < 0.001), indicated delivery (OR = 1.05, 95%CI: 1.01-1.14; P = 0.02), and before 34 weeks' gestation delivery (OR = 1.09, 95%CI: 1.03-1.18). With an AUC of 0.71, MIF showed a significantly greater discriminatory ability as compared with BMI (0.58; 95% CI: 0.52-0.65; P < 0.001), CRP (0.61; 95% CI: 0.54-0.68; P < 0.001) and IL-6(0.63; 95% CI: 0.55-0.69; P = 0.001).

CONCLUSIONS

Increased maternal plasma concentrations of MIF at first trimester were associated with increased risk of PTD and might be useful in identifying newborn at risk for PTD for early prevention strategies.

Red blood cells: The primary reservoir of macrophage migration inhibitory factor in whole blood

Red blood cells are widely accepted to be inert carriers of oxygen and haemoglobin, but there is growing evidence that they play a much more critical role in immune function. Macrophage migration inhibitory factor (MIF) is a key cytokine in disease with additional oxido-reductase activity, which aids in managing oxidative stress. Although two studies have reported the presence of MIF in red blood cells, no study has quantified the levels of this protein. In this study, freshly isolated plasma, platelets, leukocytes, and red blood cells from healthy individuals were collected and the concentration of MIF was determined using an enzyme linked immunosorbent assay. This analysis demonstrated that MIF in red blood cells was present at 25 µg per millilitre of whole blood, which is greater than99% of the total MIF and 1000-fold higher concentration than plasma. This result was supported by electrophoresis and Western blot analysis, which identified MIF in its monomer structural form following sample processing. Furthermore, by assessing the level of tautomerase activity in red blood cell fractions in the presence of a MIF inhibitor, it was determined that the red blood cell-derived MIF was also functionally active. Together, these findings have implications on the effect of haemolysis during sample preparation and provide some clue into the inflammatory processes that occur following haemolysis in vivo. These results support the hypothesis that red blood cells are a major reservoir of this inflammatory protein and may play a role in inflammation.

Modified risk associations of lipoproteins and apolipoproteins by chronic low-grade inflammation

INTRODUCTION

Lipoproteins and the apolipoproteins (apo) that they carry are major determinants of cardiovascular diseases (CVD) as well as metabolic, renal and inflammatory chronic disorders either directly or through mediation of risk factors. The notion that elevated low-density lipoprotein cholesterol (LDL-C) and apoB levels are related to the acquisition of CVD and, high-density lipoprotein cholesterol (HDL-C) and apoA-I indicate protection against CVD has been challenged in the past decade. Advanced age, adiposity, ethnicity or impaired glucose intolerance rendered autoimmune activation in an environment of pro-inflammatory state/oxidative stress and may disrupt the linear risk association between lipoproteins. Areas covered: This review summarizes the modified risk associations of lipoproteins and apolipoprotein by an environment of chronic systemic low-grade inflammation with special emphasis on the non-linear relationship of lipoprotein(a) [Lp(a)], a biomarker of renewed interest in cardiometabolic risk. Expert commentary: It seems that autoimmune activation in an environment of pro-inflammatory state/oxidative stress not only disrupts the linear risk association between lipoproteins, but also may cause interference in immunoassays. Hence, methodological improvement in immunoassays and much further research focusing on population segments susceptible to a pro-inflammatory state is necessary for further advances in knowledge.

Pre-pregnancy maternal depressive symptoms and low birth weight and preterm birth outcomes: Assessment of adolescent background characteristics and birth outcomes in adulthood

PURPOSE

In the United States and other countries of the world , high prevalence of pre-pregnancy depressive symptoms and depression during pregnancy is an important public health concern, as they are associated with low birth weight (LBW) and preterm birth (PTB) outcomes in adulthood. However, the relationships among pre-pregnancy depressive symptoms, low birth weight, preterm birth outcomes and household characteristics have not been well established.

METHODS

The study used data from 7120 adolescent female participants in the National Longitudinal Study of Adolescent to Adult Health data from Waves I (1994-1995 in-school interview), II (1996 as in-home), III (2001-2002 as in-home interview), IV (2008 as in-home interview) and Wave V is currently underway. The main outcomes were LBW and PTB. Maternal depressive symptoms were assessed with the Center for Epidemiologic Studies Depression scale (CES-D) using a cut-off point of 24 to indicate higher depressive symptoms . Odds ratios were used as an estimate of the relative risk using generalized estimating equations (GEE).

RESULTS

In Wave I, prevalence of depressive symptoms among age groups 11-15 (54.1%) was higher than older adolescents (45.9%) were. With the exception of depressive symptoms reported in Wave II, respondents reporting depressive symptoms in Waves I and III had similar unadjusted rates of LBW or PTB infants in adulthood. Mothers reporting higher depressive symptoms in older adolescence (15-19 years) had elevated odds of LBW infants (3.58 [95% CI=1.81, 7.09]) in Wave III compared with others reporting low depressive symptoms.

CONCLUSIONS

Undeniably, childhood socioeconomic circumstances are important determinants of disease risks and improved health functioning and in particular birth outcomes in adulthood. Since poorer households have fewer resources to cope with stressful events that generate mood and other depressive symptoms over the life course, findings of research suggest treating depressive symptoms prior to pregnancy will yield significant dividends for mothers and society. Furthermore, without careful control of household contexts, the association between depressive symptoms and birth outcomes is likely to be confounded.

A Dormant Microbial Component in the Development of Preeclampsia

Preeclampsia (PE) is a complex, multisystem disorder that remains a leading cause of morbidity and mortality in pregnancy. Four main classes of dysregulation accompany PE and are widely considered to contribute to its severity. These are abnormal trophoblast invasion of the placenta, anti-angiogenic responses, oxidative stress, and inflammation. What is lacking, however, is an explanation of how these themselves are caused. We here develop the unifying idea, and the considerable evidence for it, that the originating cause of PE (and of the four classes of dysregulation) is, in fact, microbial infection, that most such microbes are dormant and hence resist detection by conventional (replication-dependent) microbiology, and that by occasional resuscitation and growth it is they that are responsible for all the observable sequelae, including the continuing, chronic inflammation. In particular, bacterial products such as lipopolysaccharide (LPS), also known as endotoxin, are well known as highly inflammagenic and stimulate an innate (and possibly trained) immune response that exacerbates the inflammation further. The known need of microbes for free iron can explain the iron dysregulation that accompanies PE. We describe the main routes of infection (gut, oral, and urinary tract infection) and the regularly observed presence of microbes in placental and other tissues in PE. Every known proteomic biomarker of "preeclampsia" that we assessed has, in fact, also been shown to be raised in response to infection. An infectious component to PE fulfills the Bradford Hill criteria for ascribing a disease to an environmental cause and suggests a number of treatments, some of which have, in fact, been shown to be successful. PE was classically referred to as endotoxemia or toxemia of pregnancy, and it is ironic that it seems that LPS and other microbial endotoxins really are involved. Overall, the recognition of an infectious component in the etiology of PE mirrors that for ulcers and other diseases that were previously considered to lack one.

Biological Tools to Study the Effects of Environmental Contaminants at the Feto-Maternal Interface

The identification of reproductive toxicants is a major scientific challenge for human health. Prenatal life is the most vulnerable and important time span of human development. For obvious ethical reasons, in vivo models cannot be used in human pregnancy, and animal models do not perfectly reflect human physiology. This review describes the in vitro test models representative of the human feto-maternal interface and the effects of environmental chemicals with estrogen-like activity, mainly bisphenol A and para-nonylphenol, with a particular emphasis on the effects at low, nontoxic doses similar to concentrations commonly detected in the population.

Involvement of Visceral Adipose Tissue in Immunological Modulation of Inflammatory Cascade in Preeclampsia

Objectives. The pathophysiology of preeclampsia is characterized by abnormal placentation, an exaggerated inflammatory response, and generalized dysfunction of the maternal endothelium. We investigated the effects of preeclampsia serum on the expression of inflammation-related genes by adipose tissue. Materials and Methods. Visceral adipose tissue was obtained from the omentum of patients with early ovarian cancer without metastasis. Adipose tissue was incubated with sera obtained from either five women affected with severe preeclampsia or five women from control pregnant women at 37°C in a humidified incubator at 5% CO₂ for 24 hours. 370 genes in total mRNA were analyzed with quantitative RT-PCR (Inflammatory Response & Autoimmunity gene set). Results. Gene expression analysis revealed changes in the expression levels of 30 genes in adipose tissue treated with preeclampsia sera. Some genes are related to immune response, oxidative stress, insulin resistance, and adipogenesis, which plays a central role in excessive systemic inflammatory response of preeclampsia. In contrast, other genes have shown beneficial effects in the regulation of Th2 predominance, antioxidative stress, and insulin sensitivity. Conclusion. In conclusion, visceral adipose tissue offers protection against inflammation, oxidative insults, and other forms of cellular stress that are central to the pathogenesis of preeclampsia.

Bisphenol A modulates receptivity and secretory function of human decidual cells: an in vitro study

The human endometrium is a fertility-determining tissue and a target of steroid hormones' action. Endocrine disruptors (EDs) can exert adverse effects on the physiological function of the decidua at the maternal-fetal interface. We examined the potential effects of an ED, bisphenol A (BPA), on endometrial maturation/decidualization, receptivity, and secretion of decidual factors (biomarkers). In vitro decidualized, endometrial stromal cells from six hysterectomy specimens were treated with 1  pM-1  μM of BPA, for 24  h and assessed for cell viability and proliferation. Three non-toxic concentrations of BPA (1  μM, 1  nM, and 1  pM) were selected to study its influence on secretion of cell decidualization biomarkers (IGF-binding protein and decidual prolactin (dPRL)), macrophage migration inhibitory factor (MIF) secretion, and hormone receptors' expression (estrogen receptors (ERα and ERβ); progesterone receptors (PRA and PRB); and human chorionic gonadotropin (hCG)/LH receptor (LH-R)). The results showed a decrease in cell viability (P<0.001) in response to BPA at the level of 1  mM. At the non-toxic concentrations used, BPA perturbed the expression of ERα, ERβ, PRA, PRB, and hCG/LH-R (P<0.05). Furthermore, 1  μM of BPA reduced the mRNA transcription of dPRL (P<0.05). Secretion of MIF was stimulated by all BPA treatments, the lowest concentration (1  pM) being the most effective (P<0.001). The multi-targeted disruption of BPA on decidual cells, at concentrations commonly detected in the human population, raises great concern about the possible consequences of exposure to BPA on the function of decidua and thus its potential deleterious effect on pregnancy.

Macrophage migration inhibitory factor and placental malaria infection in an area characterized by unstable malaria transmission in central Sudan

Background: The pathogenesis of malaria during pregnancy is not fully understood. A proinflammatory cytokine, macrophage migration inhibitory factor (MIF) is suggested as a factor involved in the pathogenesis of malaria during pregnancy.

Methods: A cross-sectional study was conducted in Medani Hospital, Sudan to investigate MIF levels in placental malaria. Obstetrical and medical characteristics were gathered from each parturient woman using questionnaires. All women (151) were investigated for malaria using blood film and placental histology. MIF levels were measured using ELISA in paired maternal and cord blood samples.

Results: There were no P. falciparum-positive blood films obtained from maternal peripheral blood, placenta or cord samples. Out of 151 placentae, four (2.6%), one (0.7%), 32 (21.2%) showed acute, chronic and past infection on histopathology examinations respectively, while the rest (114; 75.5%) of them showed no signs of infection.There was no significant difference in the median (interquartile) of maternal [5.0 (3.7─8.8) vs 6.2(3.5─12.0) ng/ml, P=0.643] and cord [8.1(3.3─16.9) vs 8.3(4.2─16.9), ng/ml, P= 0.601] MIF levels between women with a positive result for placental malaria infection (n=37) and women with a negative result for placental malaria infection (n=114). In regression models placental malaria was not associated with maternal MIF, hemoglobin or birth weight. MIF was not associated with hemoglobin or birth weight .

Conclusion: There was no association between maternal and cord MIF levels, placental malaria, maternal hemoglobin and birth weight.

Self-rated health among pregnant women: associations with objective health indicators, psychological functioning, and serum inflammatory markers

BACKGROUND

Biobehavioral correlates of self-rated health in pregnancy are largely unknown.

PURPOSE

The goals of this study were to examine, in pregnant women, associations of self-rated health with (1) demographics, objective health status, health behaviors, and psychological factors, and (2) serum inflammatory markers.

METHODS

In the second trimester of pregnancy, 101 women provided a blood sample, completed measures of psychosocial stress, health status, and health behaviors, and received a comprehensive periodontal examination.

RESULTS

The following independently predicted poorer self-rated health: (1) greater psychological stress, (2) greater objective health diagnoses, (3) higher body mass index, and (4) past smoking (versus never smoking). Poorer self-rated health was associated with higher serum interleukin-1β (p = 0.02) and marginally higher macrophage migration inhibitory factor (p = 0.06). These relationships were not fully accounted for by behavioral/psychological factors.

CONCLUSIONS

This study provides novel data regarding factors influencing subjective ratings of health and the association of self-rated health with serum inflammatory markers in pregnant women.

Bisphenol A alters β-hCG and MIF release by human placenta: an in vitro study to understand the role of endometrial cells

A proper fetomaternal immune-endocrine cross-talk in pregnancy is fundamental for reproductive success. This might be unbalanced by exposure to environmental chemicals, such as bisphenol A (BPA). As fetoplacental contamination with BPA originates from the maternal compartment, this study investigated the role of the endometrium in BPA effects on the placenta. To this end, in vitro decidualized stromal cells were exposed to BPA 1 nM, and their conditioned medium (diluted 1 : 2) was used on chorionic villous explants from human placenta. Parallel cultures of placental explants were directly exposed to 0.5 nM BPA while, control cultures were exposed to the vehicle (EtOH 0.1%). After 24–48 h, culture medium from BPA-treated and control cultures was assayed for concentration of hormone human Chorionic Gonadotropin (β-hCG) and cytokine Macrophage Migration Inhibitory Factor (MIF). The results showed that direct exposure to BPA stimulated the release of both MIF and β-hCG. These effects were abolished/diminished in placental cultures exposed to endometrial cell-conditioned medium. GM-MS analysis revealed that endometrial cells retain BPA, thus reducing the availability of this chemical for the placenta. The data obtained highlight the importance of in vitro models including the maternal component in reproducing the effects of environmental chemicals on human fetus/placenta.

Lower macrophage migration inhibitory factor concentrations in maternal serum before pre-eclampsia onset

Macrophage migration inhibitory factor (MIF) plays a pivotal role in pregnancy-related proinflammatory processes, such as placentation and labor. Differential MIF concentrations have been correlated with pathological events during pregnancy, such as recurrent miscarriages and severe pre-eclampsia (PE). The aim of this study was to prospectively investigate whether maternal MIF serum levels are already altered in early pregnancy before PE onset. Women (n=2,821) before 20 weeks of gestational age were recruited for a prospective study on early markers of PE. Forty-eight consecutive pregnancies that developed PE and 79 normotensive pregnancies that delivered at term were chosen. Maternal MIF serum levels were assessed by ELISA. We found significantly lower MIF serum levels in women who developed PE (4,967 ± 3,119 pg/mL) compared to controls (7,640 ± 5,519 pg/mL) (mean ± standard deviation, P<0.001). Our findings indicate that low maternal MIF serum levels in early pregnancy may contribute to abnormal placental development.

Review: putative roles for the macrophage migratory inhibitory factor at the maternal fetal interface

Complex and dynamic networks of molecules participate in the essential interactions between maternal organism, placenta and fetus in a healthy and successful pregnancy. Macrophage migratory inhibitory factor (MIF) is one of several molecules produced at implantation sites; MIF is mostly expressed by trophoblast cells. This has led to expectations of MIF's relevance as a partner in the maternal/fetal dialog. MIF is known by its biological interactions and functional roles as an activator of innate immunity, regulating subsequent adaptive responses, which include inhibition of migration of mononuclear cells in vitro, antagonism of glucocorticoids, and regulation of expression of Toll-like receptor 4. Beyond roles in the inflammatory response, MIF can interfere with proliferative activities in different cell types, as well as with cell death pathways. This intriguing factor found at the human, porcine, ovine, bovine and rodent maternal-fetal interfaces is present in a time- and spatially-dependent manner, indicating regulatory roles in the process of embryo implantation, placental development, maintenance of pregnancy and birth. Here, we will review MIF participation in placental physiology, including new evidence for a dialog with uterine cells, and a potential role in protection of uterine decidual cells.

MicroRNA analysis in placentas from patients with preeclampsia: comparison of new and published results

OBJECTIVE

The aim was to identify differences in microRNA expression between patients with and without preeclampsia.

METHODS

Microarray-based study was carried out with placental samples.

RESULTS

Comparison of eight previous studies with the current study revealed a total of 138 microRNAs; only 20/138 (14%), however, were seen in more than one study and the results agreed in the direction of change. Bioinformatic analysis of these 20 microRNAs identified a wide range of biological functions including apoptosis and cell movement for their mRNA targets.

CONCLUSION

The associations between miRNA expression and preeclampsia suggest a potential role for microRNAs in preeclampsia pathobiology.

Pro-inflammatory profile of preeclamptic placental mesenchymal stromal cells: new insights into the etiopathogenesis of preeclampsia

The objective of the present study was to evaluate whether placental mesenchymal stromal cells (PDMSCs) derived from normal and preeclamptic (PE) chorionic villous tissue presented differences in their cytokines expression profiles. Moreover, we investigated the effects of conditioned media from normal and PE-PDMSCs on the expression of pro-inflammatory Macrophage migration Inhibitory Factor (MIF), Vascular Endothelial Growth Factor (VEGF), soluble FMS-like tyrosine kinase-1 (sFlt-1) and free β-human Chorionic Gonadotropin (βhCG) by normal term villous explants. This information will help to understand whether anomalies in PE-PDMSCs could cause or contribute to the anomalies typical of preeclampsia.

METHODS

Chorionic villous PDMSCs were isolated from severe preeclamptic (n = 12) and physiological control term (n = 12) placentae. Control and PE-PDMSCs's cytokines expression profiles were determined by Cytokine Array. Control and PE-PDMSCs were plated for 72 h and conditioned media (CM) was collected. Physiological villous explants (n = 48) were treated with control or PE-PDMSCs CM for 72 h and processed for mRNA and protein isolation. MIF, VEGF and sFlt-1 mRNA and protein expression were analyzed by Real Time PCR and Western Blot respectively. Free βhCG was assessed by immunofluorescent.

RESULTS

Cytokine array showed increased release of pro-inflammatory cytokines by PE relative to control PDMSCs. Physiological explants treated with PE-PDMSCs CM showed significantly increased MIF and sFlt-1 expression relative to untreated and control PDMSCs CM explants. Interestingly, both control and PE-PDMSCs media induced VEGF mRNA increase while only normal PDMSCs media promoted VEGF protein accumulation. PE-PDMSCs CM explants released significantly increased amounts of free βhCG relative to normal PDMSCs CM ones.

CONCLUSIONS

Herein, we reported elevated production of pro-inflammatory cytokines by PE-PDMSCs. Importantly, PE PDMSCs induced a PE-like phenotype in physiological villous explants. Our data clearly depict chorionic mesenchymal stromal cells as central players in placental physiopathology, thus opening to new intriguing perspectives for the treatment of human placental-related disorders as preeclampsia.

Intervillous macrophage migration inhibitory factor is associated with adverse birth outcomes in a study population in Central India

Macrophage migration inhibitory factor (MIF) is a pluripotent factor produced by a variety of cells. It plays an important biological role in the regulation of pregnancy and has been shown to influence malaria pathogenesis. In this study, the levels of MIF in the peripheral, cord and placental intervillous blood (IVB) plasma collected from women residing in a malaria endemic region of Central India was determined and its association with malaria in pregnancy and birth outcomes was investigated. MIF levels were significantly different in IVB, peripheral, and cord plasma, with IVB plasma having the highest MIF levels and peripheral plasma having the lowest. Placental malaria positive women had significantly higher IVB plasma MIF levels than placental malaria negative women, but this relationship was not seen in peripheral or cord plasma MIF levels. In addition, the odds of stillbirth and low birth weight deliveries for the uppermost placental MIF quartile (irrespective of placental malaria status) was significantly higher than that of the lowest placental MIF quartile, supporting the hypothesis that elevated concentrations of placental MIF may be associated with an increased risk of adverse birth outcome.

Macrophage migration inhibitory factor in fetoplacental tissues from preeclamptic pregnancies with or without fetal growth restriction

The proinflammatory cytokine MIF (macrophage migration inhibitory factor) is involved in physiological and pathological processes in pregnancy. MIF maternal serum levels are increased in preeclampsia (PE). We hypothesize that pregnancy tissues are the source of MIF overexpression in PE. MIF protein was studied in maternal sera, placental tissues, fetal membranes, and umbilical cord of 8 control and 20 PE pregnancies: 10 with normal fetal growth (PE-AGA) and 10 with fetal growth restriction (PE-FGR). MIF levels were significantly higher in PE-AGA membranes than in controls and PE-FGR. In PE-FGR, MIF cord concentrations were higher than in PE-AGA while MIF placental levels were lower than in controls. MIF maternal serum levels were higher in PE, compared to controls, and the difference was mainly due to PE-FGR samples. These data support MIF involvement in PE pathogenesis and suggest that different pregnancy tissues contribute to MIF production in PE with and without fetoplacental compromise.

17{beta}-Estradiol modulates the macrophage migration inhibitory factor secretory pathway by regulating ABCA1 expression in human first-trimester placenta

Successful pregnancy involves a series of events, most of them mediated by hormones and cytokines. Estrogens, besides being important for placental growth and embryo development, have a marked effect on the immune system exerting either pro- or anti-inflammatory properties. Numerous studies suggest that estrogens directly affect cellular function, including cytokine production. Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine involved in pregnancy, particularly during the earlier stages of placentation. Since reports on mice have shown that estrogens modulate MIF, herein we investigated the effect of estrogens on human placental MIF. By using an in vitro model of first-trimester chorionic villous explants, we found that 17beta-estradiol (E(2)) was able to modulate the release of MIF in a dose-dependent manner (10(-12) vs. 10(-9) M, P < 0.05; 10(-9) vs. 10(-5) M, P < 0.05; 10(-12) vs. 10(-5) M, P < 0.001). Unlike MIF release, no significant change in tissue MIF protein or MIF mRNA was observed. We showed evidence that E(2) concentrations (10(-9) and 10(-5) M) act on placental tissue downregulating the mRNA and protein expression of the ATP-binding cassette transporter protein A1, a membrane transporter involved in MIF secretion. These findings emphasize the mutual cooperation between hormones and cytokines and suggest that increasing estrogen levels with advancing gestation may have a major role in regulating placental MIF secretion.

Depressive symptoms predict exaggerated inflammatory responses to an in vivo immune challenge among pregnant women

OBJECTIVE

Stress and depressive symptoms predict exaggerated inflammatory responses to a biological challenge in nonpregnant humans and animals. The extent to which these findings generalize to pregnancy is unknown because the immune system exhibits substantial changes to support pregnancy. Notably, inflammatory responses to infectious agents play a causal role in the development of gestational hypertension as well as risk for preterm birth. Thus, depressive symptoms may increase susceptibility to these outcomes via sensitization of inflammatory processes. The current study was designed to test the hypothesis that depressive symptoms would predict an exaggerated proinflammatory response to an in vivo antigen challenge, influenza virus vaccination, among pregnant women.

METHOD

Twenty-two pregnant women completed two study visits: baseline and 1week after receiving influenza virus vaccination. Depressive symptoms were measured with the Center for Epidemiologic Studies Depression Scale (CES-D) at baseline. Serum levels of macrophage migration inhibitory factor (MIF) were determined using a high sensitivity immunoassay at both study visits.

OUTCOMES

Analyses demonstrated that, as compared to those in the lowest tertile of CES-D scores, those in the highest tertile exhibited significantly higher levels of MIF 1week after influenza virus vaccination (p=.035).

CONCLUSIONS

Depressive symptoms predicted exaggerated MIF production following influenza virus vaccination during pregnancy. These data support the hypothesis that depressive symptoms are associated with sensitization of the inflammatory response during pregnancy. Thus, women with greater depressive symptoms may be more vulnerable to negative sequelae of infectious illness during pregnancy.

Tissue factor and its natural inhibitor in pre-eclampsia and SGA

OBJECTIVE

Tissue factor (TF), the major activator of the extrinsic pathway of coagulation, is abundant in the placenta and decidua. The aim of this study was to determine the maternal plasma concentrations of TF and its primary inhibitor, tissue factor pathway inhibitor (TFPI), in women who delivered small for gestational age (SGA) neonates, and in pre-eclampsia.

STUDY DESIGN

A cross-sectional study included the following groups: 1) women with normal pregnancies (n = 86); 2) patients who delivered SGA neonates (n = 61) and 3) women with pre-eclampsia (n = 133). Maternal plasma concentrations of TF and TFPI were measured by a sensitive immunoassay. Non-parametric statistics were used for analysis.

RESULTS

1) Women with pre-eclampsia had a significantly higher median plasma concentration of TF than patients with a normal pregnancy (median: 1187 pg/mL; range: 69-11675 vs. median: 291.5 pg/mL; range: 6.3-2662.2; p < 0.0001, respectively); 2) Similarly, TFPI concentrations were higher in pre-eclampsia than in normal pregnancy (median: 87.5 ng/mL; range 25.4-165.1 vs. median: 66.1 ng/mL; range: 14.3-86.5; p < 0.0001, respectively); 3) Surprisingly, mothers with SGA neonates had a lower median maternal plasma concentration of TF (median: 112.2 pg/mL; range: 25.6-1225.3) than women with a normal pregnancy (p < 0.0001).

CONCLUSION

1) Maternal plasma concentrations of TF in patients with pre-eclampsia, but not in those who delivered an SGA neonate, were higher than in women with normal pregnancies; 2) Although the role of immunoreactive plasma TF in coagulation remains controversial, our observations suggest that changes are present in the context of complications of pregnancy.

Over-expression of the thrombin receptor (PAR-1) in the placenta in preeclampsia: a mechanism for the intersection of coagulation and inflammation

OBJECTIVE

Preeclampsia (PE) is characterized by excessive thrombin generation, which has been implicated in the multiple organ damage associated with the disease. The biological effects of thrombin on coagulation and inflammation are mediated by protease-activated receptor-1 (PAR-1), a G protein-coupled receptor. The aim of this study was to determine whether preterm PE is associated with changes in placental expression of PAR-1.

STUDY DESIGN

This cross-sectional study included two groups matched for gestational age at delivery: (1) patients with preterm PE (<37 weeks of gestation; n = 26) and (2) a control group of patients with preterm labor without intra-amniotic infection (n = 26). Placental tissue microarrays were immunostained for PAR-1. Immunoreactivity of PAR-1 in the villous trophoblasts was graded as negative, weak-positive, or strong-positive.

RESULTS

(1) The proportion of cases with strong PAR-1 immunoreactivity was significantly higher in placentas of patients with PE than in placentas from the control group (37.5% (9/24) vs. 8.7% (2/23); p = 0.036, respectively). (2) PAR-1 immunoreactivity was found in the cellular compartments of the placental villous tree, mainly in villous trophoblasts and stromal endothelial cells. (3) PAR-1 was detected in 92.3% (24/26) of the placentas of women with PE and in 88.5% (23/26) of the placentas from the control group.

CONCLUSION

Placentas from pregnancies complicated by preterm PE had a significantly higher frequency of strong PAR-1 expression than placentas from women with spontaneous preterm labor. This observation is consistent with a role for PAR-1 as a mediator of the effect of thrombin on coagulation and inflammation in PE. We propose that the effects of thrombin in PE are due to increased thrombin generation and higher expression of PAR-1, the major receptor for this enzyme.

Serum macrophage migration inhibitory factor in the prediction of preterm delivery

OBJECTIVE

Macrophage migration inhibitory factor is a soluble mediator that helps govern the interaction between cytokines and stress hormones (eg, cortisol). We determined whether maternal macrophage migration inhibitory factor levels predicted subsequent preterm delivery.

STUDY DESIGN

A nested case-control study measuring serum macrophage migration inhibitory factor concentration at 9-23 weeks' gestation in women who ultimately delivered preterm (n = 60) compared with control women who delivered at term (n = 122). We also examined the connection of macrophage migration inhibitory factor with self-reported psychosocial variables.

RESULTS

Macrophage migration inhibitory factor was elevated in the preterm delivery cases (P = .0004), and log macrophage migration inhibitory factor concentration showed a graded response relationship with likelihood of preterm delivery. High-macrophage migration inhibitory factor was also associated with maternal risk-taking behavior, which itself was a risk factor for preterm delivery. Macrophage migration inhibitory factor remained associated independently with preterm delivery after adjusting regression models for several other preterm delivery risk factors (odds ratio, 3.11, 95% confidence interval, 1.54-6.30).

CONCLUSION

High-serum macrophage migration inhibitory concentration in early to midpregnancy is linked with subsequent preterm delivery.

Pre-eclampsia is associated with Helicobacter pylori seropositivity in Italy

OBJECTIVES

Pre-eclampsia (PE) is characterized by an excess of inflammation and endothelial dysfunction. Helicobacter pylori (H. pylori) causes chronic inflammatory changes and endothelial damage. We investigated the prevalence of seropositivity for IgG against H. pylori and cytotoxin-associated antigen A (CagA) in PE patients and the presence of H. pylori DNA in their placentas.

METHODS

We tested 47 pregnant women with PE and 47 with uneventful pregnancies for serum antibodies against H. pylori (enzyme immunoassays) and CagA protein (immunoblot assays). In 20 of them (10 normal and 10 PE) we assessed the presence, in the placenta, of H. pylori DNA by means of nested polymerase chain reaction (PCR). The odds ratios (OR) and 95% confidence intervals (CI), adjusted for parity, were calculated using logistic regression analysis to assess the risk of PE associated with H. pylori infection.

RESULTS

Helicobacter pylori seropositivity frequency was higher in mothers with PE (51.1%) compared to women with uneventful pregnancy (31.9%) (OR, 2.668; 95% CI, 1.084-6.566; P = 0.033). The difference was even greater for CagA seropositivity (80.9 and 14.9%, respectively) (OR, 26.035; 95% CI, 8.193-82.729; P < 0.001). All placentas were negative for H. pylori DNA.

CONCLUSIONS

Helicobacter pylori, and especially strains carrying the CagA gene, may contribute to the inflammatory mechanisms involved in the pathogenesis of PE.

The role of macrophage migration inhibitory factor in maintaining the immune privilege at the fetal–maternal interface

Macrophage migration inhibitory factor (MIF) is a pivotal regulator of the innate and adaptive immunity affecting the response and behavior of macrophages and lymphocytes. MIF is also implicated in other fundamental cellular processes including angiogenesis and cell proliferation. Several studies examined the expression of MIF in reproductive organs and tissues and its involvement in different aspects of human and animal reproduction. The goal of this review was to summarize these findings and discuss, in particular, the role of MIF in the maintenance of the immune privilege at the human fetal-maternal interface.

Inflammatory Changes in Preeclampsia: Current Understanding of the Maternal Innate and Adaptive Immune Response

Preeclampsia is characterized by generalized endothelial dysfunction as a result of an inappropriate maternal immune response against the fetus. It has been postulated that the adaptive immune system plays a key role in the etiology of preeclampsia by generating a pro-inflammatory Th1 type immune reaction. In this review, recent studies on Th1 and Th2 type cytokine mapping in preeclampsia are reviewed, as well as on the sources of pro-inflammatory cytokines and the role of regulatory cytokines and chemokines. In addition, we discuss the possible role of Toll-like receptors of the innate immune system in the pathophysiology of preeclampsia.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to summarize the newer concepts related to the pathogenesis of preeclampsia and explain the role of the maternal immune system and the role of pro-inflammatory and regulatory cytokines and chemokines in the pathophysiology of the disease.

Oxygen regulation of macrophage migration inhibitory factor in human placenta

Macrophage migration inhibitory factor (MIF) is an important proinflammatory cytokine involved in regulation of macrophage function. In addition, MIF may also play a role in murine and human reproduction. Although both first trimester trophoblast and decidua express MIF, the regulation and functional significance of this cytokine during human placental development remains unclear. We assessed MIF expression throughout normal human placental development, as well as in in vitro (chorionic villous explants) and in vivo (high altitude placentae) models of human placental hypoxia. Dimethyloxalylglycine (DMOG), which stabilizes hypoxia inducible factor-1 under normoxic conditions, was also used to mimic the effects of hypoxia on MIF expression. Quantitative real-time PCR and Western blot analysis showed high MIF protein and mRNA expression at 7-10 wk and lower levels at 11-12 wk until term. Exposure of villous explants to 3% O(2) resulted in increased MIF expression and secretion relative to standard conditions (20% O(2)). DMOG treatment under 20% O(2) increased MIF expression. In situ hybridization and immunohistochemistry showed elevated MIF expression in low oxygen-induced extravillous trophoblast cells. Finally, a significant increase in MIF transcript was observed in placental tissues from high-altitude pregnancies. Hence, three experimental models of placental hypoxia (early gestation, DMOG treatment, and high altitude) converge in stimulating increased MIF, supporting the conclusion that placental-derived MIF is an oxygen-responsive cytokine highly expressed in physiological in vivo and in in vitro low oxygen conditions.

Proinflammatory macrophage migratory inhibition factor and interleukin-6 are concentrated in pleural effusion of human fetuses with prenatal chylothorax

OBJECTIVES

To study the role of selected cytokines and growth factors involved in the pathogenesis of fetal chylous pleural effusion.

METHODS

Seventeen fetuses with prenatal chylothorax at gestational age (GA) 17-29 weeks were enrolled as the study group during the period 2003-2005. Their pleural effusion (n = 17) and amniotic fluid (n = 17) were drawn when disease set in. Eleven fetuses received cordocentesis because of suspected fetal anemia. Forty-one normal fetuses without adverse perinatal outcome at GA 17-29 weeks received amniocentesis and were enrolled in the reference group. Levels of hepatocyte growth factor (HGF), stromal-derived factor-1(SDF-1), vascular endothelial growth factor (VEGF), interleukin-8 (IL-8), macrophage migratory inhibition factor (MIF), and interleukin-6 (IL-6) were determined in the samples from both groups (amniotic fluid, pleural fluid, and cord blood from the study group and amniotic fluid from the reference group) by enzyme-linked immunoassay (EIA).

RESULTS

No significant differences were observed in the amniotic fluids between the study group and the reference group regarding levels of IL-6, IL-8, MIF, SDF-1, HGF and VEGF. In the study group, levels of IL-8, VEGF and SDF-1 (all pro-angiogenic) showed no significant differences between the amniotic fluid, cord blood and pleural effusion. The level of HGF (proangiogenic) was significantly higher in the amniotic fluid than in the cord blood or the pleural effusion, but there were no significant differences between the levels in the pleural fluid and in the cord blood. Interestingly, the levels of MIF and IL-6 (both are proinflammatory) in the amniotic fluid and in the pleural effusion were much higher than the levels in the cord blood.

CONCLUSION

Our study demonstrated that the levels of pro-inflammatory proteins (MIF and IL-6) that we tested were higher in the fetal pleural effusion than in the fetal circulation, a phenomenon not observed in the levels of proangiogenic proteins (HGF, SDF-1, VEGF, IL-8). This result implies that inflammation-related proteins may be more relevant than the angiogenesis-related proteins in the local environment of accumulating pleural effusion, a prominent feature of prenatal chylothorax.

Macrophage migration inhibitory factor-nitric oxide interaction in human fetal membranes at term pregnancy

OBJECTIVES

Macrophage migration inhibitory factor (MIF), a multifunctional proinflammatory cytokine, has been recently involved in many aspects of reproduction including pregnancy. However, no evidence is available on the role of MIF in gestational tissues nor on factors regulating MIF production. This study, conducted on explants of human fetal membranes at term gestation, has been undertaken to investigate whether: (1) MIF is produced by fetal membranes; (2) nitric oxide (NO) can regulate local MIF production; and (3) MIF, in turn, can influence NO release in these tissues.

METHODS

Tissues were obtained from 56 healthy women who underwent elective cesarean delivery. Fetal membranes have been incubated with either sodium nitroprusside (NP), a NO donor, or recombinant MIF (r-MIF), or a specific anti-MIF antibody (MIF-Ab). Reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot, enzyme-linked immunosorbent assay (ELISA), and colorimetric assay have been used to detect MIF mRNA and protein, inducible nitric oxide synthase (iNOS), and NO metabolites.

RESULTS

Fetal membranes basally express MIF mRNA and protein and release MIF. Exposing tissues to NP results in an increase of MIF mRNA expression and protein release. Conversely, treatment of tissues with MIF is followed by a reduction in iNOS mRNA and protein expression as well as in NO release. These effects are reversed by adding MIF-Ab.

CONCLUSIONS

MIF is generated and released by human fetal membranes at term. MIF mRNA and protein expression and release are modulated by NO. MIF, in turn, can reduce iNOS expression and NO release by these tissues. NO could be a regulator of MIF production in pregnancy and labor.

Disturbances in placental immunology: ready for therapeutic interventions?

Recent studies have provided new insight into aberrations in the immunological interplay between mother and fetus and their potential role in the development of recurrent fetal loss and preeclampsia. The action of anti-phospholipid antibodies in recurrent fetal loss is now proposed to involve the complement system, neutrophil activation and the production of TNFalpha by immune bystander cells. A clear involvement of the immune system is emerging in preeclampsia, involving mainly the innate arm, especially neutrophils. The activation of peripheral neutrophils by placentally released inflammatory debris triggers the induction of neutrophil extracellular traps (NETs), which may lead to an occlusion of the intervillous space, thereby further promoting a condition of placental hypoxia. It has, hence, been suggested that new therapeutic strategies be developed, including the possible use of TNFalpha antagonists in cases of recurrent miscarriage. These strategies need to be addressed with caution due to the possible induction of fetal congenital abnormalities.

Macrophage migration inhibition factor is elevated in pregnancy, but not to a greater extent in preeclampsia

BACKGROUND

Maternal serum concentrations of macrophage migration inhibitory factor (MIF) have recently been reported to be elevated in cases with preeclampsia. These findings may be important in increasing our understanding of the underlying events leading to the development of preeclampsia, as this cytokine is also expressed in the placenta, where it has been shown to possess immunemodulatory activities. For this reason we attempted to independently verify this report.

METHODS

Plasma levels of MIF were assessed by ELISA in plasma samples collected from normal healthy male and female blood donors (n=20 per group), as well as healthy normal pregnant women in all three trimesters of pregnancy (n=60). In addition, MIF levels were examined from cases with mild and severe preeclampsia (n=20 per study cohort) and matched normotensive pregnancies (n=20).

RESULTS

MIF levels were found to be elevated in pregnancy (median=10.1 ng/ml) when compared to non-pregnant controls (median=1.7 ng/ml). A moderate, but not significant, elevation was found to occur from the first to the third trimester of pregnancy. No significant difference was found to occur between the two preeclampsia study groups when compared to the normotensive control group.

CONCLUSIONS

Our data suggest that circulatory MIF concentrations are elevated throughout pregnancy, but are not further increased in preeclampsia.