Placental fractalkine immunoreactivity in preeclampsia and its correlation with histopathological changes in the placenta and adverse pregnancy outcomes. J Matern Fetal Neonatal Med 2018;33:806-815. [PMID: 30049235 DOI: 10.1080/14767058.2018.1505854]

CX3CL1 (Fractalkine): An important cytokine in physiological and pathological pregnancies

C-X3-C motif chemokine ligand 1 (CX3CL1), commonly known as Fractalkine, is an important chemokine with dual functions of chemotaxis and adhesion. It plays a pivotal role in a variety of physiological processes and pathological conditions, particularly in conjunction with its receptor, C-X3-C motif chemokine receptor 1 (CX3CR1). This review focuses on the expression and intricate regulatory mechanisms of CX3CL1 at the maternal-fetal interface, emphasizing its multifaceted role during pregnancy. CX3CL1 was detected in the trophoblast and decidua tissues, playing a crucial role in recruitment of immune cells, enhancing endometrial receptivity, and modulating trophoblast cell activities. Abnormal expression of CX3CL1 has been correlated with adverse pregnancy outcomes such as spontaneous abortion, gestational diabetes, preeclampsia, and preterm births. By elucidating the complex interplay of CX3CL1 at the maternal-fetal interface, this review aims to shed light on its potential roles in pregnancy-related complications.

High expression of CX3CL1/CX3CR1 at the mother-fetus interface of preeclampsia inhibits trophoblast invasion and migration

INTRODUCTION

Preeclampsia is associated with maternal inflammatory overreaction and imbalanced immunity at the mother-fetus interface. The pro-inflammatory chemokine fractalkine (CX3CL1) is recently recognized apart from imbalanced immunity. In this study, CX3CL1- CX3C chemokine receptor 1(CX3CR1) regulation of decidual macrophage function and trophoblast invasion ability in preeclampsia was initially explored.

METHODS

The study comprised 60 women allocated to NP group (normotensive pregnant woman, n = 30) and sPE group (woman with severe preeclampsia, n = 30). After the delivery, the expression of CX3CL1 in placental tissues of the two groups was detected by immunohistochemical analysis. The protein level of CX3CL1 in placental tissue and CX3CR1 in decidua tissue was detected by Western Blot and the localization of CX3CR1 expression in decidua was detected by immunofluorescence. Macrophages were polarized into classically activated (M1) macrophages. M1 were treat with PBS (control group), recombinant human CX3CL1 (CX3CL1 group), recombinant human CX3CL1+ selective CX3CR1 antagonist-JMS-17-2 (CX3CL1+anti-CX3CR1 group) and recombinant human CX3CL1 + selective CX3CR1 antagonist-JMS-17-2 + VS-6063 (CX3CL1+anti-CX3CR1+ FAK inhibitor group). M1 and HTR8/SVneo cells were co-cultured as described previously to assess invasion and migration capacity by transwell assays and Wound-healing assay.

RESULTS

In this study, CX3CL1 expression is high in the placental tissues of severe preeclampsia (sPE) patients than in normotensive pregnancies (NP). CX3CR1 expression is high in the decidual tissues of severe preeclampsia patients and mainly expressed in macrophages of decidual tissues. CX3CL1/CX3CR1 decreased VEGF expression in M1 macrophages and reduced the invasion and migration function of HTR-8/SVneo through the FAK signaling pathway.

DISCUSSION

These findings revealed that CX3CL1-CX3CR1 regulate the trophoblast function by FAK and provided new insights into the pathogenesis of preeclampsia.

Multi-Layered Mechanisms of Immunological Tolerance at the Maternal-Fetal Interface

Pregnancy represents an immunological paradox where the maternal immune system must tolerate the semi-allogeneic fetus expressing paternally-derived Ags. Accumulating evidence over decades has revealed that successful pregnancy requires the active development of robust immune tolerance mechanisms. This review outlines the multi-layered processes that establish fetomaternal tolerance, including the physical barrier of the placenta, restricted chemokine-mediated leukocyte trafficking, lack of sufficient alloantigen presentation, the presence of immunosuppressive regulatory T cells and tolerogenic decidual natural killer cells, expression of immune checkpoint molecules, specific glycosylation patterns conferring immune evasion, and unique metabolic/hormonal modulations. Interestingly, many of the strategies that enable fetal tolerance parallel those employed by cancer cells to promote angiogenesis, invasion, and immune escape. As such, further elucidating the mechanistic underpinnings of fetal-maternal tolerance may reciprocally provide insights into developing novel cancer immunotherapies as well as understanding the pathogenesis of gestational complications linked to dysregulated tolerance processes.

Eucommia granules activate Wnt/β-catenin pathway, and improve oxidative stress, inflammation, and endothelial injury in preeclampsia rats

PURPOSE

Pre-eclampsia (PE) is a pregnancy-related complication. Eucommia is effective in the treatment of hypertensive disorders in pregnancy, but the specific effects and possible mechanisms of Eucommia granules (EG) in PE remain unknown. The aim of this study was to investigate the effects and possible mechanisms of EG in PE rats.

METHODS

Pregnant Sprague Dawley rats were divided into five groups (n = 6): the control group, the model group, the low-dose group, the medium-dose group, and the high-dose group of EG. The PE model was established by subcutaneous injection of levonitroarginine methyl ester. Saline was given to the blank and model groups, and the Eucommia granules were given by gavage to the remaining groups. Blood pressure and urinary protein were detected. The body length and weight of the pups and the weight of the placenta were recorded. Superoxide dismutase (SOD) activity and levels of malondialdehyde (MDA), placental growth factor (PIGF), and soluble vascular endothelial growth factor receptor-1 (sFIt-1) were measured in the placenta. Pathological changes were observed by hematoxylin-eosin staining. Wnt/β-catenin pathway-related protein expression was detected using Western blot.

RESULTS

Compared with the model group, the PE rats treated with EG had lower blood pressure and urinary protein. The length and weight of the pups and placental weight were increased. Inflammation and necrosis in the placental tissue was improved. SOD level increased, MDA content and sFIt-1/PIGF ratio decreased, and Wnt/β-catenin pathway-related protein expression level increased. Moreover, the results of EG on PE rats increased with higher doses of EG.

CONCLUSIONS

EG may activate the Wnt/β-catenin pathway and inhibit oxidative stress, inflammation, and vascular endothelial injury in PE rats, thereby improving the perinatal prognosis of preeclamptic rats. EG may inhibit oxidative stress, inflammation, and vascular endothelial injury through activation of the Wnt/β-catenin pathway in preeclampsia rats, thereby improving perinatal outcomes in PE rats.

Pathophysiological impact of CXC and CX3CL1 chemokines in preeclampsia and gestational diabetes mellitus

Diabetes-related pathophysiological alterations and various female reproductive difficulties were common in pregnant women with gestational diabetes mellitus (GDM), who had 21.1 million live births. Preeclampsia (PE), which increases maternal and fetal morbidity and mortality, affects approximately 3%-5% of pregnancies worldwide. Nevertheless, it is unclear what triggers PE and GDM to develop. Therefore, the development of novel moderator therapy approaches is a crucial advancement. Chemokines regulate physiological defenses and maternal-fetal interaction during healthy and disturbed pregnancies. Chemokines regulate immunity, stem cell trafficking, anti-angiogenesis, and cell attraction. CXC chemokines are usually inflammatory and contribute to numerous reproductive disorders. Fractalkine (CX3CL1) may be membrane-bound or soluble. CX3CL1 aids cell survival during homeostasis and inflammation. Evidence reveals that CXC and CX3CL1 chemokines and their receptors have been the focus of therapeutic discoveries for clinical intervention due to their considerable participation in numerous biological processes. This review aims to give an overview of the functions of CXC and CX3CL1 chemokines and their receptors in the pathophysiology of PE and GDM. Finally, we examined stimulus specificity for CXC and CX3CL1 chemokine expression and synthesis in PE and GDM and preclinical and clinical trials of CXC-based PE and GDM therapies.

The pathogenesis of obstetric APS: a 2023 update

The antiphospholipid syndrome (APS) is an autoimmune disease characterized by the persistent presence of antibodies directed against phospholipids and phospholipid-binding proteins that are associated with thrombosis and pregnancy-related morbidity. The latter includes fetal deaths, premature birth and maternal complications. In the early 1990s, a distinct set of autoantibodies, termed collectively antiphospholipid antibodies (aPL), were identified as the causative agents of this disorder. Subsequently histological analyses of the placenta from APS pregnancies revealed various abnormalities, including inflammation at maternal-fetal interface and poor placentation manifested by reduced trophoblast invasion and limited uterine spiral artery remodeling. Further preclinical investigations identified the molecular targets of aPL and the downstream intracellular pathways of key placental cell types. While these discoveries suggest potential therapeutics for this disorder, definitive clinical trials have not been completed. This concise review focuses on the recent developments in the field of basic and translational research pursuing novel mechanisms underlying obstetric APS.

Fetal microchimerism and the two-stage model of preeclampsia

Fetal cells cross the placenta during pregnancy and some have the ability to persist in maternal organs and circulation long-term, a phenomenon termed fetal microchimerism. These cells often belong to stem cell or immune cell lineages. The long-term effects of fetal microchimerism are likely mixed, potentially depending on the amount of fetal cells transferred, fetal-maternal histocompatibility and fetal cell-specific properties. Both human and animal data indicate that fetal-origin cells partake in tissue repair and may benefit maternal health overall. On the other hand, these cells have been implicated in inflammatory diseases by studies showing increased fetal microchimerism in women with autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. During pregnancy, preeclampsia is associated with increased cell-transfer between the mother and fetus, and an increase in immune cell subsets. In the current review, we discuss potential mechanisms of transplacental transfer, including passive leakage across the compromised diffusion barrier and active recruitment of cells residing in the placenta or fetal circulation. Within the conceptual framework of the two-stage model of preeclampsia, where syncytiotrophoblast stress is a common pathophysiological pathway to maternal and fetal clinical features of preeclampsia, we argue that microchimerism may represent a mechanistic link between stage 1 placental dysfunction and stage 2 maternal cardiovascular inflammation and endothelial dysfunction. Finally, we postulate that fetal microchimerism may contribute to the known association between placental syndromes and increased long-term maternal cardiovascular disease risk. Fetal microchimerism research represents an exciting opportunity for developing new disease biomarkers and targeted prophylaxis against maternal diseases.

Risk factors associated with cesarean section and adverse fetal outcomes in intrahepatic cholestasis of pregnancy

Background

To determine the risk factors for cesarean section (CS) and adverse fetal outcomes (AFOs) in patients with intrahepatic cholestasis of pregnancy (ICP) based on the severity of maternal hypercholanemia.

Methods

A hospital-based retrospective cohort study was performed between January 1, 2015, and December 31, 2019. A total of 227 nulliparous women with a singleton fetus complicated by ICP were included. The patients were divided into two groups according to the levels of total bile acids, that is, mild (10 μmol/L < total bile acids < 40 μmol/L) and severe (≥40 μmol/L). The patients' clinical characteristics and fetal outcomes were assessed.

Results

Among the 227 eligible women, 177 (78.0%) were allocated to the mild group and 50 (22.0%) were in the severe group. Women with severe ICP also had a significantly higher incidence of planned and unplanned CS compared with mild ICP subjects (52.0% vs. 23.7% and 22.0% vs. 6.8%, respectively; p < 0.001). The indications for CS showed that fetal intolerance (65.4% vs. 14.3%) was higher in severe ICP compared with mild ICP (p < 0.001). Severe ICP was associated with an increased risk of preterm delivery (p < 0.001), low birthweight (p = 0.001), and neonatal intensive care unit (NICU) admission (p < 0.001). Women with severe ICP (OR 6.397, 95%CI 3.041-13.455, p < 0.001) or preeclampsia (OR 12.434, 95%CI 5.166-29.928, p < 0.001) had increased risks of AFOs compared to controls.

Conclusions

Severe ICP and preeclampsia are associated with a higher incidence of AFOs.

Critical Role for Macrophages in the Developmental Programming of Pancreatic β-Cell Area in Offspring of Hypertensive Pregnancies

Preeclampsia is a pregnancy-specific complication with long-term negative outcomes for offspring, including increased susceptibility to type 2 diabetes (T2D) in adulthood. In a rat reduced uteroplacental perfusion pressure (RUPP) model of chronic placental ischemia, maternal hypertension in conjunction with intrauterine growth restriction mimicked aspects of preeclampsia and resulted in female embryonic day 19 (e19) offspring with reduced β-cell area and increased β-cell apoptosis compared with offspring of sham pregnancies. Decreased pancreatic β-cell area persisted to postnatal day 13 (PD13) in females and could influence whether T2D developed in adulthood. Macrophage changes also occurred in islets in T2D. Therefore, we hypothesized that macrophages are crucial to reduction in pancreatic β-cell area in female offspring after chronic placental ischemia. Macrophage marker CD68 mRNA expression was significantly elevated in e19 and PD13 islets isolated from female RUPP offspring compared with sham. Postnatal injections of clodronate liposomes into female RUPP and sham offspring on PD2 and PD9 significantly depleted macrophages compared with injections of control liposomes. Depletion of macrophages rescued reduced β-cell area and increased β-cell proliferation and size in RUPP offspring. Our studies suggest that the presence of macrophages is important for reduced β-cell area in female RUPP offspring and changes in macrophages could contribute to development of T2D in adulthood.

Chronic Venous Disease during Pregnancy Causes a Systematic Increase in Maternal and Fetal Proinflammatory Markers

Chronic venous disease (CVD) is a common vascular disorder characterized by increased venous hypertension and insufficient venous return from the lower limbs. Pregnancy is a high-risk situation for developing CVD. Approximately a third of the women will develop this condition during pregnancy, and similarly to arterial hypertensive disorders, previous evidence has described a plethora of alterations in placental structure and function in women with pregnancy-induced CVD. It is widely known that arterial-induced placenta dysfunction is accompanied by an important immune system alteration along with increased inflammatory markers, which may provide detrimental consequences for the women and their offspring. However, to our knowledge, there are still no data collected regarding cytokine profiling in women with pregnancy-induced CVD. Thus, the aim of the present work was to examine cytokine signatures in the serum of pregnant women (PW) with CVD and their newborns (NB). This study was conducted through a multiplex technique in 62 PW with pregnancy-induced CVD in comparison to 52 PW without CVD (HC) as well as their NB. Our results show significant alterations in a broad spectrum of inflammatory cytokines (IL-6, IL-12, TNF-α, IL-10, IL-13, IL-2, IL-7, IFN-γ, IL-4, IL-5, IL-21, IL-23, GM-CSF, chemokines (fractalkine), MIP-3α, and MIP-1β). Overall, we demonstrate that pregnancy-induced CVD is associated with a proinflammatory environment, therefore highlighting the potentially alarming consequences of this condition for maternal and fetal wellbeing.

Role of chemokines in early pregnancy loss

The present study aimed to compare decidual protein levels and gene expression levels of chemokines between patients with early pregnancy loss and those with voluntary abortion. A total of 15 patients between 6 and 10 gestational weeks, who presented with negative fetal heartbeat to the obstetrics and gynecology outpatient clinics of Gaziosmanpasa Hospital (Yeni Yuzyil University, Istanbul, Turkey) and who had no additional systemic disease and 13 patients between 6 and 10 gestational weeks, who presented with positive fetal heartbeat for voluntary abortion were included in the present study. CX3CL1, CCL17, CXCR4, chemokine ligand 12 (CXCL12) and intercellular adhesion molecule (ICAM)5 protein expression levels were determined by ELISA and gene expression levels by reverse transcription-quantitative PCR in fresh materials recovered after therapeutic curettage. CX3CL1, CCL17, CXCR4, CXCL12 protein levels were significantly higher and ICAM protein level was significantly lower in pregrant women with missed abortion compared with those with voluntary abortion. While the amount of increase in mean CX3CL1, CCL17, CXCR4 and CXCL12 gene expression levels in the tissues of pregnant women with missed abortion was statistically higher than the pregnant women who underwent voluntary abortion, the amount of increase in ICAM5 gene expression was found to be lower (P<0.001) in those with missed abortion. In conclusion, the findings of the present study suggested that CCL17, CX3CL1, CXCL12, CXCR4 and ICAM5 may be associated with missed abortion and may play an important role in placental invasion and the continuation of pregnancy.

Immunogenetic aspects of idiopathic recurrent miscarriage in the Kazakh population

There are numerous scientific studies of recurrent miscarriage (RM) with possible causes, such as fetal chromosomal abnormalities, infectious agents, adverse environmental factors, bad habits, anatomical defects, thrombophilic disorders, etc. However, RM causes in 50% of cases remain unknown. These RM cases do not have any explainable etiology, and they require in-depth etiopathogenesis study, thus they are considered idiopathic RM. The purpose of this research is to study polymorphisms relationship of the immune response genes CX3CR1 (rs3732379, Val249Ile), CTLA4 (rs3087243, CT60 G/A), and HLA DQA1, DQB1, DRB1 (major histocompatibility complex, class II) with the idiopathic form of recurrent miscarriage (iRM) development in Kazakh population. Independent replicative TagMan genotyping for 302 patients with iRM and 300 women with normal reproduction was performed. It has been shown that carriage of unfavorable genotypes (Val/Ile, Val/Val) by the Val249Ile polymorphism of the CX3CR1 gene increases the risk of developing iRM by 1.43 times. Search for associations of genes allelic variants of HLA class 2 complex with iRM revealed *501 allele in DQA1 locus, *0301 in DQB1 locus, *10, *12, *15, *16 alleles in DRB1 locus, which increases the risk of developing iRM in Kazakh population with OR from 1.34 to 4.5. As a result of the study, obtained highly significant associations of immune response genes with the development of iRM in the Kazakh population indicate the possible involvement of the immune system interaction of mother cells with syncytiotrophoblast, which is realized by vascularization defects, defective embryo implantation, and leads to early pregnancies' termination.

Duration of the pushing phase of labor is inversely associated with expression of TNF, IL6, IGF1 and IGF2 in human placenta

OBJECTIVE

Gene expression in placenta differs between vaginal and cesarean deliveries, but the influence of the duration of labor on placental gene expression is incompletely known. Our aim was to investigate associations between duration of labor and expression of some genes involved in growth or inflammation in human placental tissue.

METHODS

Placenta samples (n = 126) were collected after an uncomplicated, singleton pregnancy and term vaginal delivery at Örebro University Hospital, Sweden. Duration of labor was recorded by the midwife in the delivery room. The expression of the following genes was analyzed by RT-qPCR: tumor necrosis factor (TNF), interleukin-6 (IL6), C-X-C motif chemokine ligand 8, toll-like receptor (TLR) 2, TLR4, insulin receptor, insulin-like growth factor (IGF) 1, IGF2, leptin, hepatocyte growth factor (HGF) and HGF receptor (MET). Multivariable linear regression models were used for the evaluation of associations with labor duration adjusting for potential confounding factors. The Benjamini-Hoschberg method was used to correct for multiple testing.

RESULTS

The expression of TNF, IL6, IGF1 and IGF2 was inversely associated with the duration of the pushing phase of labor (B coefficients (95% confidence interval) = -0.150 (-0.277 to -0.023), -0.159 (-0.289 to -0.029), -0.099 (-0.176 to -0.021), and -0.081 (-0.145 to -0.017), respectively).

CONCLUSIONS

Longer duration of pushing is associated with downregulation of the expression of genes in placenta from vaginal deliveries. Future research on gene expression in labored placenta should take into account associations with labor duration and especially the pushing phase. Potential impact of these associations on the mother, the fetus and the new-born infant should also be explored.

Data-driven discovery of mid-pregnancy immune markers associated with maternal lifetime stress: results from an urban pre-birth cohort

Changes to the maternal inflammatory milieu may be a mechanism through which maternal psychosocial stress is transmitted to the fetus. Research investigating a limited number of immune markers may miss important signals. We take a proteomics approach to investigate maternal lifetime stress and 92 biomarkers of immune system status. Participants were enrolled in an urban, dual-site (Boston, n = 301 and New York City, n = 110) pregnancy cohort. We measured maternal lifetime history of stress and trauma using the validated Life Stressor Checklist-Revised (LSC-R). We measured a panel of 92 immune-related proteins in mid-pregnancy serum using proximity extension assay technology. We leveraged the dual-site study design to perform variable selection and inference within the cohort. First, we used LASSO to select immune markers related to maternal stress among Boston mothers. Then, we performed OLS regression to examine associations between maternal stress and LASSO-selected proteins among New York City mothers. LASSO regression selected 19 immune proteins with non-null coefficients (CCL11, CCL23, CD244, CST5, CXCL1, CXCL5, CXCL10, CX3CL1, FGF-23, IL-5, IL-7, IL-10, IL-17C, MCP-2, MMP-1, SLAMF1, ST1A1, TNF-β, and TWEAK). Of these, only the chemotactic cytokine CX3CL1 (i.e. fractalkine) was significantly associated with maternal stress among the validation sample (percent change in LSC-R score per 1% increase in relative fractalkine expression: 0.74, 95% confidence interval: 0.19, 1.28). Expanding research suggests fractalkine plays an important role in many aspects of pregnancy and fetal development and is stress-sensitive. We found that maternal lifetime history of stress and trauma was significantly associated with elevated serum fractalkine levels during pregnancy.

Overexpression of fractalkine and its histopathological characteristics in primary pterygium

PURPOSE

This study aimed to evaluate the differences in the expressions of fractalkine in normal bulbar conjunctiva and primary pterygium tissues.

METHODS

The study included 48 patients who had been operated on for primary pterygium. Histopathologically, the presence of epithelial atypia, epithelial hyperplasia, goblet cell hyperplasia, epithelial lymphocytic exocytosis, stromal inflammation, mast cell count, and stromal vascularity were evaluated in the primary pterygium tissues. An immunohistochemical fractalkine stain was applied to the primary pterygium tissue samples and normal bulbar conjunctival tissue samples.

RESULTS

Primary pterygium and normal bulbar conjunctival tissue samples were histopathologically analyzed. Epithelial atypia, epithelial hyperplasia, epithelial lymphocytic exocytosis, stromal inflammation, stromal vascularity, and mast cell count were found to be significantly higher in the primary pterygium (p = 0.001, p = 0.002, p = 0.024, p = 0.007, p = 0.024, and p = 0.013, respectively). When evaluated in terms of fractalkine expression, the epithelial, vascular endothelial, and inflammatory cells were significantly higher in the primary pterygium (p ≤ 0.001, p = 0.002, p = 0.001, respectively). Moreover, compared to the normal bulbar conjunctiva, Ki-67 expression was significantly higher in the primary pterygium tissue samples.

CONCLUSION

Fractalkine might play a key role in the etiopathogenesis of pterygium. Fractalkine may be important in developing new treatment approaches.

Placental CX3CL1 is Deregulated by Angiotensin II and Contributes to a Pro-Inflammatory Trophoblast-Monocyte Interaction

CX3CL1, which is a chemokine involved in many aspects of human pregnancy, is a membrane-bound chemokine shed into circulation as a soluble isoform. Placental CX3CL1 is induced by inflammatory cytokines and is upregulated in severe early-onset preeclampsia. In this study, the hypothesis was addressed whether angiotensin II can deregulate placental CX3CL1 expression, and whether CX3CL1 can promote a pro-inflammatory status of monocytes. qPCR analysis of human placenta samples (n = 45) showed stable expression of CX3CL1 and the angiotensin II receptor AGTR1 throughout the first trimester, but did not show a correlation between both or any influence of maternal age, BMI, and gestational age. Angiotensin II incubation of placental explants transiently deregulated CX3CL1 expression, while the angiotensin II receptor antagonist candesartan reversed this effect. Overexpression of recombinant human CX3CL1 in SGHPL-4 trophoblasts increased adhesion of THP-1 monocytes and significantly increased IL8, CCL19, and CCL13 in co-cultures with human primary monocytes. Incubation of primary monocytes with CX3CL1 and subsequent global transcriptome analysis of CD16⁺ subsets revealed 81 upregulated genes, including clusterin, lipocalin-2, and the leptin receptor. Aldosterone synthase, osteopontin, and cortisone reductase were some of the 66 downregulated genes present. These data suggest that maternal angiotensin II levels influence placental CX3CL1 expression, which, in turn, can affect monocyte to trophoblast adhesion. Release of placental CX3CL1 could promote the pro-inflammatory status of the CD16⁺ subset of maternal monocytes.