Oxidative damage, inflammation, and Toll-like receptor 4 pathway are increased in preeclamptic patients: a case-control study

Tandem mass tag-based proteomics analysis reveals the mechanism underlying the interleukin-6-mediated regulation of trophoblast function in preeclampsia

OBJECTIVE

We investigated the mechanism whereby interleukin-6 (IL-6), an important inflammatory marker, influences trophoblast function during preeclampsia.

METHODS

Quantitative PCR and enzyme-linked immunosorbent assay were used to determine the IL-6 mRNA and protein levels, respectively. CCK8 and transwell assays were used to detect how IL-6 affects the proliferation and invasion abilities of HTR-8/SVneo cells respectively; the tube-forming assay was conducted to explore how IL-6 affects the angiogenesis ability of human umbilical vein endothelial cells (HUVECs) after their co-culture with HTR-8/SVneo cells. Using tandem mass tag-based proteomics analysis, we screened for different proteins before and after IL-6 stimulation; Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed to investigate the functions and signal pathways associated with these proteins.

RESULTS

The IL-6 levels were higher in the placenta of preeclampsia group than in the normal group. IL-6 suppressed the proliferation and invasion of HTR-8/SVneo cells, but promoted the angiogenesis of HUVECs. Seventy differentially expressed IL-6 downstream proteins were identified; these were enriched with various biological processes, molecular functions, cellular components, and biological pathways.Conclusions: IL-6 regulates trophoblast function by interacting with multiple proteins and pathways. Proteomics-based screening serves as a macroscopic approach to clarify the molecular mechanisms associated with preeclampsia.

Longitudinal Assessment of Oxidative Stress Markers in Women with Preeclampsia

Preeclampsia (PE) is a pregnancy-specific disorder and a major contributor to maternal and fetal morbidity and mortality. Role of oxidative stress in early pregnancy with the pathophysiology of the disorder is unclear. The current study aims to analyse maternal levels of oxidative stress markers (MDA and protein carbonyl) longitudinally across gestation and placental levels of oxidative stress markers (MDA, protein carbonyl and 8-oxo-2'-deoxyguanosine) in women with PE and compare them with non-PE women. 324 pregnant women (216 non-PE and 108 PE women) were longitudinally followed during pregnancy. Women with preeclampsia were stratified as early onset preeclampsia (EOP) and late onset preeclampsia (LOP) Maternal blood at four time points across gestation (11-14 weeks, 18-22 weeks, 26-28 weeks, and at delivery) and placenta were collected. Maternal and placental levels of oxidative stress markers were assessed using commercially available kits. Maternal plasma MDA and protein carbonyl levels were comparable between the PE and non-PE group at all timepoints across gestation. Maternal plasma MDA were significantly higher levels at 26-28 weeks in EOP women when compared to non-PE women (p < 0.05). Placental 8-oxo-dG levels were lower in the EOP group as compared to non-PE (p < 0.05). Elevated plasma MDA levels were positively associated with birth length at 18-22 weeks and 26-28 weeks in the PE group (p < 0.05 for both). Maternal plasma MDA levels were positively associated with systolic blood pressure at 18-22 weeks. Oxidative stress in early pregnancy is not associated with risk of PE.

Inflammation and Oxidative Stress Induced by Obesity, Gestational Diabetes, and Preeclampsia in Pregnancy: Role of High-Density Lipoproteins as Vectors for Bioactive Compounds

Inflammation and oxidative stress are essential components in a myriad of pathogenic entities that lead to metabolic and chronic diseases. Moreover, inflammation in its different phases is necessary for the initiation and maintenance of a healthy pregnancy. Therefore, an equilibrium between a necessary/pathologic level of inflammation and oxidative stress during pregnancy is needed to avoid disease development. High-density lipoproteins (HDL) are important for a healthy pregnancy and a good neonatal outcome. Their role in fetal development during challenging situations is vital for maintaining the equilibrium. However, in certain conditions, such as obesity, diabetes, and other cardiovascular diseases, it has been observed that HDL loses its protective properties, becoming dysfunctional. Bioactive compounds have been widely studied as mediators of inflammation and oxidative stress in different diseases, but their mechanisms of action are still unknown. Nonetheless, these agents, which are obtained from functional foods, increase the concentration of HDL, TRC, and antioxidant activity. Therefore, this review first summarizes several mechanisms of HDL participation in the equilibrium between inflammation and oxidative stress. Second, it gives an insight into how HDL may act as a vector for bioactive compounds. Third, it describes the relationships between the inflammation process in pregnancy and HDL activity. Consequently, different databases were used, including MEDLINE, PubMed, and Scopus, where scientific articles published in the English language up to 2023 were identified.

IL-6 and IL-8: An Overview of Their Roles in Healthy and Pathological Pregnancies

Interleukin-6 (IL-6) is an acknowledged inflammatory cytokine with a pleiotropic action, mediating innate and adaptive immunity and multiple physiological processes, including protective and regenerative ones. IL-8 is a pro-inflammatory CXC chemokine with a primary function in attracting and activating neutrophils, but also implicated in a variety of other cellular processes. These two ILs are abundantly expressed at the feto-maternal interface over the course of a pregnancy and have been shown to participate in numerous pregnancy-related events. In this review, we summarize the literature data regarding their role in healthy and pathological pregnancies. The general information related to IL-6 and IL-8 functions is followed by an overview of their overall expression in cycling endometrium and at the feto-maternal interface. Further, we provide an overview of their involvement in pregnancy establishment and parturition. Finally, the implication of IL-6 and IL-8 in pregnancy-associated pathological conditions, such as pregnancy loss, preeclampsia, gestational diabetes mellitus and infection/inflammation is discussed.

Hypertension: Potential Player in Cardiovascular Disease Incidence in Preeclampsia

Preeclampsia (PE) is one of the complications, that threatens pregnant mothers during pregnancy. According to studies, it accounts for 3-7% of all pregnancies, and also is effective in preterm delivery. PE is the third leading cause of death in pregnant women. High blood pressure in PE can increase the risk of developing cardiovascular disease (CVD) in cited individuals, and is one of the leading causes of death in PE individuals. Atrial natriuretic peptide (ANP), Renin-Angiotensin system and nitric oxide (NO) are some of involved factors in regulating blood pressure. Therefore, by identifying the signaling pathways, that are used by these molecules to regulate and modulate blood pressure, appropriate treatment strategies can be provided to reduce blood pressure through target therapy in PE individuals; consequently, it can reduce CVD risk and mortality.

The Placental Innate Immune System Is Altered in Early-Onset Preeclampsia, but Not in Late-Onset Preeclampsia

Preeclampsia is a severe placenta-related pregnancy disorder that is generally divided into two subtypes named early-onset preeclampsia (onset <34 weeks of gestation), and late-onset preeclampsia (onset ≥34 weeks of gestation), with distinct pathophysiological origins. Both forms of preeclampsia have been associated with maternal systemic inflammation. However, alterations in the placental immune system have been less well characterized. Here, we studied immunological alterations in early- and late-onset preeclampsia placentas using a targeted expression profile approach. RNA was extracted from snap-frozen placenta samples (healthy n=13, early-onset preeclampsia n=13, and late-onset preeclampsia n=6). The expression of 730 immune-related genes from the Pan Cancer Immune Profiling Panel was measured, and the data were analyzed in the advanced analysis module of nSolver software (NanoString Technology). The results showed that early-onset preeclampsia placentas displayed reduced expression of complement, and toll-like receptor (TLR) associated genes, specifically TLR1 and TLR4. Mast cells and M2 macrophages were also decreased in early-onset preeclampsia compared to healthy placentas. The findings were confirmed by an immunohistochemistry approach using 20 healthy, 19 early-onset preeclampsia, and 10 late-onset preeclampsia placentas. We conclude that the placental innate immune system is altered in early-onset preeclampsia compared to uncomplicated pregnancies. The absence of these alterations in late-onset preeclampsia placentas indicates dissimilar immunological profiles. The study revealed distinct pathophysiological processes in early-onset and late-onset preeclampsia placentas and imply that a tailored treatment to each subtype is desirable.

Medawar's PostEra: Galectins Emerged as Key Players During Fetal-Maternal Glycoimmune Adaptation

Lectin-glycan interactions, in particular those mediated by the galectin family, regulate many processes required for a successful pregnancy. Over the past decades, increasing evidence gathered from in vitro and in vivo experiments indicate that members of the galectin family specifically bind to both intracellular and membrane bound carbohydrate ligands regulating angiogenesis, immune-cell adaptations required to tolerate the fetal semi-allograft and mammalian embryogenesis. Therefore, galectins play important roles in fetal development and placentation contributing to maternal and fetal health. This review discusses the expression and role of galectins during the course of pregnancy, with an emphasis on maternal immune adaptions and galectin-glycan interactions uncovered in the recent years. In addition, we summarize the galectin fingerprints associated with pathological gestation with particular focus on preeclampsia.

Characterisation of cardiac health in the reduced uterine perfusion pressure model and a 3D cardiac spheroid model, of preeclampsia

Background

Preeclampsia is a dangerous cardiovascular disorder of pregnancy that leads to an increased risk of future cardiovascular and metabolic disorders. Much of the pathogenesis and mechanisms involved in cardiac health in preeclampsia are unknown. A novel anti-angiogenic protein, FKBPL, is emerging as having a potential role in both preeclampsia and cardiovascular disease (CVD). Therefore, in this study we aimed to characterise cardiac health and FKBPL regulation in the rat reduced uterine perfusion pressure (RUPP) and a 3D cardiac spheroid model of preeclampsia.

Methods

The RUPP model was induced in pregnant rats and histological analysis performed on the heart, kidney, liver and placenta (n ≥ 6). Picrosirius red staining was performed to quantify collagen I and III deposition in rat hearts, placentae and livers as an indicator of fibrosis. RT-qPCR was used to determine changes in Fkbpl, Icam1, Vcam1, Flt1 and Vegfa mRNA in hearts and/or placentae and ELISA to evaluate cardiac brain natriuretic peptide (BNP45) and FKBPL secretion. Immunofluorescent staining was also conducted to analyse the expression of cardiac FKBPL. Cardiac spheroids were generated using human cardiac fibroblasts and human coronary artery endothelial cells and treated with patient plasma from normotensive controls, early-onset preeclampsia (EOPE) and late-onset preeclampsia (LOPE); n = 3. FKBPL and CD31 expression was quantified by immunofluorescent labelling.

Results

The RUPP procedure induced significant increases in blood pressure (p < 0.001), collagen deposition (p < 0.001) and cardiac BNP45 (p < 0.05). It also induced a significant increase in cardiac FKBPL mRNA (p < 0.05) and protein  expression  (p < 0.01). RUPP placentae also exhibited increased collagen deposition and decreased Flt1 mRNA expression (p < 0.05). RUPP kidneys revealed an increase in average glomerular size (p < 0.05). Cardiac spheroids showed a significant increase in FKBPL expression when treated with LOPE plasma (p < 0.05) and a trend towards increased FKBPL expression following treatment with EOPE plasma (p = 0.06).

Conclusions

The rat RUPP model induced cardiac, renal and placental features reflective of preeclampsia. FKBPL was increased in the hearts of RUPP rats and cardiac spheroids treated with plasma from women with preeclampsia, perhaps reflective of restricted angiogenesis and inflammation in this disorder. Elucidation of these novel FKBPL mechanisms in cardiac health in preeclampsia could be key in preventing future CVD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-021-00376-1.

Evaluation of carcinoembryonic antigen-related cell adhesion molecule 1 blood serum levels in women at high risk for preeclampsia

PROBLEM

The aim of this study was to evaluate the sCEACAM1 concentrations in serum from patients in the first trimester who have a high risk for developing PE during pregnancy.

METHOD OF THE STUDY

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) levels were determined with ELISA. The patients (n = 109) were divided into two groups: patients who have a high risk of developing PE early-onset and a control group. Patients who have a high risk of developing PE were then divided into two subgroups depending on PE development in third trimester of pregnancy: PE in third trimester versus no PE in third trimester.

RESULTS

sCEACAM1 concentrations in patients who were screened as having a high risk for developing PE were significantly higher than in healthy pregnant women in the first trimester (p = .03). The highest sCEACAM1 concentration was found in the high-risk group with PE development compared to the control group (p = .004).

CONCLUSION

Elevated sCEACAM1 blood serum levels in women with PE suggest that there is immune dysregulation in early pregnancy, which may be helpful in PE prediction and therapy.

Silibinin induces in vitro M2-like phenotype polarization in monocytes from preeclamptic women

Preeclampsia (PE) is a pregnancy-specific syndrome featuring intense activation of circulating monocytes and an imbalance between pro- and anti-inflammatory cytokines. The present study evaluated the immunomodulatory effect of silibinin (Sb) on the expression of surface markers and the nuclear transcription factor NF-κB signalling pathway of monocytes from preeclamptic women. Monocytes were cultured with or without Sb, and the mean fluorescence intensity of the surface molecules TLR4, CD64, and CD163 as well as the intracellular transcription factors IκB-α and NF-κBp65 was analysed by flow cytometry. The concentration of cytokines in the monocyte culture supernatant was determined by cytometric bead array and ELISA immunoassay. The results showed that the in vitro treatment of monocytes from preeclamptic women with Sb downregulated the endogenous activation of NF-κB and the expression of surface receptors TLR4 and CD64, and reduced the synthesis of the pro-inflammatory cytokines interleukin 1 (IL-1β), IL-6, IL-8, IL-12p70, IL-23, and tumour necrosis factor alpha (TNF-α) compared with cultures not treated with Sb. The presence of this flavonoid in monocyte cultures increased the expression of CD163 and IκBα and the release of IL-10 and transforming growth factor beta (TGF-β) in the culture supernatants, polarising these cells from the M1-like profile to the M2-like profile. The anti-inflammatory activity of Sb on the NF-κB activation pathway and induction of cell polarisation to the M2 profile was confirmed by an in vitro assay using monocytes from healthy, non-pregnant women. Treatment of monocytes from preeclamptic women with Sb polarises the cells to the M2-like phenotype, suggesting that this flavonoid has an immunomodulatory effect on the sterile inflammation characteristic of PE.

Reduced Intellectual Ability in Offspring Born from Preeclamptic Mothers: A Prospective Cohort Study

Background

Severe preeclampsia may affect placental development, and high homocysteine (Hcy) levels are linked to intellectual disability. However, the correlation between perinatal Hcy levels and intellectual ability remains unknown in severe preeclampsia-affected offspring.

Objective

We aimed to investigate the intellectual ability in offspring born from preeclamptic mothers and examine the role of prenatal Hcy in the prediction of intellectual disability in preschool-aged offspring.

Methods

The IQ scores were compared between 101 children born to mothers with severe preeclampsia and 202 offsprings born to normotensive mothers. Maternal Hcy levels within 7 days prior to delivery and postnatal cord blood Hcy were measured. The associations of Hcy with IQ scores were evaluated, and the optimal cut-off values for predicting intellectual disability in the offspring were estimated.

Results

The children born to mothers with severe preeclampsia had a greater postnatal cord blood Hcy than those born from normotensive mothers (P < 0.001), and the mothers with severe preeclampsia presented a higher prenatal Hcy (P < 0.001). The children born to mothers with severe preeclampsia had significantly lower IQ scores than those born from normotensive mothers, and a higher Hcy was associated with a lower IQ in preeclampsia-affected offspring. The prevalence of intellectual disability was 2.86 times higher in severe preeclampsia-affected offspring than in children born from normotensive mothers, and the prevalence of low IQ was greater in children born to mothers with severe preeclampsia than in those from normotensive mothers. ROC curve analysis showed that both maternal and cord blood Hcy were predictors of intellectual disability, and the optimal cut-off for predicting intellectual disability was 17.7 and 9.75 μmol/L for maternal and cord blood Hcy.

Conclusion

Perinatal exposure to severe preeclampsia has an adverse effect on postnatal intellectual development, and high maternal and cord blood Hcy may contribute to this association.

Galectin-7 Impairs Placentation and Causes Preeclampsia Features in Mice

Preeclampsia is a serious pregnancy-induced disorder unique to humans. The etiology of preeclampsia is poorly understood; however, poor placental formation is thought causal. Galectin-7 is produced by trophoblast and is elevated in first-trimester serum of women who subsequently develop preeclampsia. We hypothesized that elevated placental galectin-7 may be causative of preeclampsia. Here, we demonstrated increased galectin-7 production in chorionic villous samples from women who subsequently develop preterm preeclampsia compared with uncomplicated pregnancies. In vitro, galectin-7 impaired human first-trimester trophoblast outgrowth, increased placental production of the antiangiogenic sFlt-1 splice variant, sFlt-1-e15a, and reduced placental production and secretion of ADAM12 (a disintegrin and metalloproteinase12) and angiotensinogen. In vivo, galectin-7 administration (E8-E12) to pregnant mice caused elevated systolic blood pressure, albuminuria, impaired placentation (reduced labyrinth vascular branching, impaired decidual spiral artery remodeling, and a proinflammatory placental state demonstrated by elevated IL1β, IL6 and reduced IL10), and dysregulated expression of renin-angiotensin system components in the placenta, decidua, and kidney, including angiotensinogen, prorenin, and the angiotensin II type 1 receptor. Collectively, this study demonstrates that elevated galectin-7 during placental formation contributes to abnormal placentation and suggests that it leads to the development of preeclampsia via altering placental production of sFlt-1 and renin-angiotensin system components. Targeting galectin-7 may be a new treatment option for preeclampsia.

Oxidative stress markers in preeclamptic placentas: A systematic review with meta-analysis

INTRODUCTION

Oxidative stress (OS) is the basis of several diseases. Preeclampsia (PE) is a multisystemic syndrome, considered one of the major causes of maternal and fetal mortality. The placenta is considered the main anatomical pathogenetic substrate for the disease, being the placental OS a likely critical pathway in the pathogenesis of PE. This meta-analysis aimed to verify whether there is OS in the preeclamptic placenta and which markers are altered in this condition.

METHODS

The search was conducted in the following databases: MEDLINE (via PubMed), Lilacs and Scopus. Relevant studies were identified until May 2020. The quality of the studies was evaluated according to the Newcastle-Ottawa scale.

RESULTS

From the 3998 screened records, 43 were finally included in the systematic review, and 23 in the meta-analysis. The biomarkers evaluated were related to cell and macromolecules' damage, such as malondialdehyde (MDA), 8-hydroxy-2'-deoxyguanosine (8-OH-dG), lipid peroxides, isoprostane, total oxidant status (TOS), carbonylated proteins and some of the reactive oxygen and nitrogen species (RONS), like hydrogen peroxide and nitric oxide. It was also related to antioxidant activity, both enzymatic, including superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione S-transferase and total antioxidant status, and non-enzymatic, through quantification of reduced glutathione, vitamin C and E, zinc and copper.

CONCLUSION

It was observed that there was OS in the preeclamptic placentas, based on results, like lower activity of some of the enzymes of the antioxidant system (SOD and GPx) as well as the increase in oxidative damage markers (MDA and lipid peroxide), corroborating literature data.

Increased TLR4 pathway activation and cytokine imbalance led to lipopolysaccharide tolerance in monocytes from preeclamptic women

Preeclampsia (PE) is a pregnancy syndrome characterized by a systemic inflammatory response, and endogenous activation of monocytes. This study aimed to determine whether the activation of monocytes from preeclamptic women might interfere with the response to lipopolysaccharide (LPS)-in vitro stimulation. Fifty-two preeclamptic women and 32 normotensive (NT) pregnant women were included. Monocytes from peripheral blood were cultured with or without LPS. TLR4 expression was analyzed by flow cytometry, NF-κB activity was determined in nuclear extracts and cytokines production was evaluated by ELISA. Endogenous TLR4 ligands such as Hyaluronan, HMGB1 and Hsp70 were determined in plasma. The endogenous TLR4 expression and activation of NF-κB were statistically higher in monocytes from women with PE compared to NT group. Early-onset PE showed higher TLR4 expression compared to late-onset PE. Plasma levels of Hyaluronan, HMGB1, and Hsp70, as well as endogenous production of inflammatory cytokines, were elevated whilst lower production of IL-10 was observed in the PE group. After culture with LPS, monocytes presented lower NF-κB activation, TNF-α and IL-12 production in PE groups than in the NT group. The study demonstrates endogenous activation of monocytes from preeclamptic women, accompanied by higher expression of TLR4, NF-κB activation and elevated production of pro-inflammatory cytokines. The higher plasma levels of the TLR4 ligands hyaluronan, HMGB1 and hsp70, as well as the high concentration of TNF-α endogenously produced by monocytes, could induce the LPS tolerance phenomenon in these cells. These results suggest that monocytes play an important role in the maternal excessive systemic inflammatory response in PE.

LPS Induces Preeclampsia-Like Phenotype in Rats and HTR8/SVneo Cells Dysfunction Through TLR4/p38 MAPK Pathway

Accumulating evidence has shown that preeclampsia (PE) was associated with an aberrant maternal-fetal inflammatory response. In the present study, we first found that in human PE placentas levels of toll-like receptor 4 (TLR4), phosphorylated p38 mitogen-activated protein kinase (p-p38 MAPK) and inflammatory cytokines IL-6 and MCP-1 were significantly upregulated. Next, we demonstrated a notable increase in systolic blood pressure (SBP) and proteinuria in lipopolysaccharide (LPS)-treated pregnant rats and concomitant high levels of TLR4 and p-p38 in these PE-like rat placentas, which led to aberrant overexpression of both IL-6 and MCP-1, as well as deficient trophoblast invasion and spiral artery (SA) remodeling, and these abnormalities were ameliorated by SB203580, a reported inhibitor of p38. In vitro we further confirmed that LPS triggered the activation of TLR4/p38 signaling pathway, which promoted trophoblast apoptosis and damaged trophoblastic invasion via downstream effectors IL-6 and MCP-1; these mutations were rectified by silencing this signaling pathway. These findings elaborated potential mechanisms that aberrant TLR4/p38 signaling might contribute to PE and LPS-induced PE-like symptom by damaging trophoblast invasion and SA remodeling via activating inflammatory cytokines including IL-6 and MCP-1.

Urinary protein carbonyl levels and its correlation with protein misfolding in preeclampsia

OBJECTIVE

To evaluate the association of protein carbonylation with preeclampsia and its correlation with urinary protein misfolding.

METHOD

Protein carbonyl and misfolded protein levels were measured in the midstream urine sample (58 preeclamptic and 44 normotensive pregnancy) by ELISA and Congo Red Dot assay respectively.

RESULTS

Significant difference was observed in the levels of protein carbonyls (P = 0.002) and misfolded proteins (P = 0.001). Correlation between protein carbonyl and misfolded proteins levels was significant but weak (r = 0.3; P = 0.018).

CONCLUSION

Urinary protein carbonyl level is elevated in preeclampsia but plays a minor role in proteins misfolding.

Inflammatory Markers and Preeclampsia: A Systematic Review

BACKGROUND

Preeclampsia (PE), a serious and variable pregnancy complication affecting 5%-10% of the obstetric population, has an undetermined etiology, yet inflammation is concomitant with its development, particularly in relation to endothelial dysfunction.

OBJECTIVE

The purpose of this systematic review was to examine the published evidence concerning an association between PE and inflammatory markers for their usefulness in the prediction or early identification of women with PE in antepartum clinical settings.

METHODS

In this systematic review, we used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The Cumulative Index for Nursing and Allied Health and MEDLINE/OVID were the electronic databases used for identifying published articles. We placed no time limit on the publication year.

RESULTS

The search generated 798 articles. After removing duplicates, screening abstracts, and conducting full-text reviews, we retained 73 articles and examined 57 unique markers. This review shows that C-reactive protein and the cytokines, specifically the proinflammatory markers IL-6, IL-8, and tumor necrosis factor alpha, garner the most support as potential inflammatory markers for clinical surveillance of PE, particularly during the second and third trimesters.

DISCUSSION

Based on this review, we cannot recommend any single inflammatory marker for routine clinical use to predict/identify PE onset or progression. Research is recommended to examine a combination panel of these four inflammatory markers both with and without clinical risk factors toward the goal of translation to practice.

Placental inflammation by HMGB1 activation of TLR4 at the syncytium

INTRODUCTION

Normal pregnancy is characterized by an elevated inflammatory state involving the placenta. The placental inflammation is further increased in preeclampsia, resulting in release of harmful danger signals to the maternal circulation. Activation of toll-like receptors (TLR)2 and TLR4 by endogenous danger signals plays a role in inflammatory diseases. Placental TLR2 and TLR4 expression has been reported, and high mobility group box 1 (HMGB1) is a likely endogenous activator of these receptors. We aimed to examine HMGB1 activation of TLR2 and TLR4 as mechanisms of placental inflammation in normal and preeclamptic pregnancies, by combined analysis of expression and function of the ligand HMGB1, the receptors TLR2 and TLR4, and the cytokine responder interleukin (IL)-8.

METHODS

Protein expression was analyzed in placental tissue from normal and preeclamptic pregnancies, and cytokine responses to two distinct HMGB1 isoforms were examined in placental explants and trophoblasts. Inflammatory and anti-angiogenic markers were measured in maternal serum.

RESULTS

We demonstrated strong co-localized expression of HMGB1, TLR4 and IL-8 in the syncytium layer of the placenta. Syncytium TLR4 expression and maternal serum levels of IL-8 were significantly increased in preeclamptic compared to normal pregnancies. Functionality was confirmed by TLR4-dependent release of IL-8 from placental explants and trophoblasts in response to the inflammatory isoform of HMGB1.

DISCUSSION

This demonstrates a role for the HMGB1-TLR4 pathway at the syncytium layer and suggests involvement in placental inflammation and preeclampsia.

Disruption in the Regulation of Immune Responses in the Placental Subtype of Preeclampsia

Preeclampsia is a pregnancy-specific disorder, of which one of its major subtypes, the placental subtype is considered a response to an ischemic placental environment, impacting fetal growth and pregnancy outcome. Inflammatory immune responses have been linked to metabolic and inflammatory disorders as well as reproductive failures. In healthy pregnancy, immune regulatory mechanisms prevent excessive systemic inflammation. However, in preeclampsia, the regulation of immune responses is disrupted as a result of aberrant activation of innate immune cells and imbalanced differentiation of T-helper cell subsets creating a cytotoxic environment in utero. Recognition events that facilitate immune interaction between maternal decidual T cells, NK cells, and cytotrophoblasts are considered an indirect cause of the incomplete remodeling of spiral arteries in preeclampsia. The mechanisms involved include the activation of immune cells and the subsequent secretion of cytokines and placental growth factors affecting trophoblast invasion, angiogenesis, and eventually placentation. In this review, we focus on the role of excessive systemic inflammation as the result of a dysregulated immune system in the development of preeclampsia. These include insufficient control of inflammation, failure of tolerance toward paternal antigens at the fetal-maternal interface, and subsequent over- or insufficient activation of immune mediators. It is also possible that external stimuli, such as bacterial endotoxin, may contribute to the excessive systemic inflammation in preeclampsia by stimulating the release of pro-inflammatory cytokines. In conclusion, a disrupted immune system might be a predisposing factor or result of placental oxidative stress or excessive inflammation in preeclampsia. Preeclampsia can thus be considered a hyperinflammatory state associated with defective regulation of the immune system proposed as a key element in the pathological events of the placental subtype of this disorder.

Both maternal and placental toll-like receptor activation are necessary for the full development of proteinuric hypertension in mice

OBJECTIVE

Innate immune system activation and excessive inflammation contributes to hypertension during pregnancy (HTN-preg). Activation of Toll-like receptors (TLRs), the primary innate immune system sensor, is evident in women with HTN-preg and is sufficient to induce pregnancy-dependent, proteinuric hypertension in animals. However, whether HTN-preg is a maternal disease, a placental disease, or both is unclear. We hypothesized that activation of TLR3, the double-stranded RNA sensor, in both maternal systemic and placental cells would be necessary for the full development of HTN-preg in mice.

STUDY DESIGN

Various mating schemes generated pregnant mice that lacked TLR3 in maternal cells, paternally-derived placental cells, and both. Mice were then injected with a TLR3 agonist on days 13, 15, and 17 of pregnancy.

MAIN OUTCOME MEASURES

Blood pressure, urinary protein excretion, fetal development, maternal vascular endothelial function, and immune system activation were all assessed and compared between groups.

RESULTS

Pregnant mice lacking TLR3 in maternal cells as well as pregnant mice lacking TLR3 in placental cells had significantly attenuated increases in systolic blood pressure, urinary protein excretion, fetal demise, and endothelial dysfunction compared to wild-type pregnant mice following TLR3 activation. Pregnant mice lacking TLR3 in both maternal systemic and placental cells were completely resistant to the hypertension, proteinuria, fetal demise, endothelial dysfunction, splenomegaly, and increases in pro-inflammatory immune cells induced by TLR3 activation.

CONCLUSIONS

These data suggest that both maternal and placental TLR3 activation are crucial for the full development of HTN-preg and that TLR3 antagonists may be beneficial in some women with HTN-preg.

Soluble B7-H4 blood serum levels are elevated in women at high risk for preeclampsia in the first trimester, as well as in patients with confirmed preeclampsia

PROBLEM

B7-H4 negatively regulates T-cell-mediated immunity and might play an important role in preeclampsia (PE). Here, we have investigated the association between PE and maternal soluble B7-H4 (sB7-H4) serum levels and B7-H4 mRNA expression in the placenta.

METHOD OF STUDY

Maternal serum levels of sB7-H4 were determined by enzyme-linked immunosorbent assay in women between 11 and 13 weeks' gestation with elevated risk for PE (n = 48) and women without elevated risk for PE (n = 47). In the third trimester, sB7-H4 serum levels (n = 166) and B7-H4 mRNA expression in the placenta (n = 54) were determined in women with early-onset PE, late-onset PE, fetal growth restriction (FGR), and in healthy controls.

RESULTS

In the first trimester, significant higher levels of sB7-H4 were detected in women at elevated risk for PE compared to women without risk for PE (P < .0001). sB7-H4 has some predictive ability to identify cases with an elevated risk of developing PE with area under the curve (AUC) value of 0.88 (95% CI 0.8-0.94). Using a specificity of 90.0% led to a sensitivity of 47.9% and a threshold of 3.63 ng/mL. In the third trimester, the highest serum levels of sB7-H4 and B7-H4 mRNA expression in the placenta were observed in early-onset PE. Significant higher serum levels of sB7-H4 and B7-H4 mRNA expression in the placenta were observed in women with early-onset PE (P = .01 and P = .006, respectively) and late-onset PE (P = .03 and P = .004, respectively) compared to healthy controls, but not compared to FGR.

CONCLUSION

sB7-H4 is involved in the regulation of immune tolerance in women with PE in the third trimester. In the first trimester of pregnancy, sB7-H4 might serve as a predictive immunological biomarker for women who are at elevated risk of developing PE.

Increased serum levels of high mobility group protein B1 and calprotectin in pre-eclampsia

OBJECTIVE

To determine whether women with pre-eclampsia have serum levels of biomarkers indicative of an elevated systemic inflammatory response.

METHOD

The present cross-sectional study was conducted among pregnant women either with pre-eclampsia or without pre-eclampsia who were recruited at a single Chinese hospital between August 1, 2016, and April 30, 2017. Eligible women had no history of acute or chronic inflammation. Serum concentrations of high mobility group protein B1 (HMG-1), calprotectin, and Toll-like receptor 4 (TLR4) were measured and compared.

RESULTS

There were 55 patients included (25 with pre-eclampsia and 30 without). The mean serum concentration of calprotectin was 2656.76 ± 1724.56 μg/L in the pre-eclampsia group versus 1877.33 ± 905.69 μg/L in the control group (P=0.036). Among patients with pre-eclampsia, elevated calprotectin levels were positively associated with the duration of hypertension in pregnancy (P=0.031) and were negatively associated with pregnancy duration at delivery (P=0.035). The mean serum concentration of HMG-1 was 72.48 ± 27.57 μg/L in the pre-eclampsia group versus 57.57 ± 20.07 μg/L in the control group (P=0.017). The mean serum concentration of TLR4 was 22.83 ± 8.46 μg/L in the pre-eclampsia group versus 18.83 ± 6.79 μg/L in the control group (P=0.057).

CONCLUSION

Elevated levels of HMG-1 and calprotectin could reflect an excessive systemic inflammatory response in pre-eclampsia.

Role of Innate Immunity in Preeclampsia: A Systematic Review

Innate immune system dysfunction has been known to be a key player in preeclampsia (PE). Activation of the maternal innate immunity may be triggered by invading microorganisms or endogenous ligands, which are detected by different pattern recognition receptors (PRRs). Although some studies have linked PRR activation to PE, it is still unclear if dysregulated PRR expression is associated with the development of this complication. Therefore, we conducted a systematic review of the literature, searching articles that evaluated associations of PRRs with PE. Twenty-six studies met the inclusion criteria: 20 of them analyzed PRR expressions and 6 studies investigated the association between PRR polymorphisms and PE. Among the PRRs, only few studies analyzed retinoic acid-inducible gene I-like helicase (RLH) and/or toll-like receptor (TLR)-1, 5, 6, 7, 8, and 9 expressions in immune cells or placentas from women with PE and controls; thus, it is inconclusive if these PRRs are involved in PE. Results from the 10 studies that analyzed TLR-2 expressions in women with PE and controls are also contradictory. The majority of the studies that investigated TLR-3 and -4 expressions indicate that these PRRs are increased in placenta or immune cells from women with PE compared to pregnant control woman. To date, polymorphisms in TLR-2, - 3, and - 4 and nucleotide-binding oligomerization domain-like receptor 2 genes do not seem to be associated with PE development. No study has evaluated the association between polymorphisms in genes codifying other TLRs or RLHs genes. In conclusion, available data in literature support a role for TLR-3 and TLR-4 in the pathogenesis of PE.

Immunohistochemical Expression of Myeloperoxidase in Placental Samples of Systematic Lupus Erythematosus Pregnancies

OBJECTIVE

Reports of increased level of Myeloperoxidase (MPO) in plasma and placental extracts of Systematic Lupus Erythematosus (SLE) has been proposed that MPO may have an important role in this pregnancy complication. In present study immunohistochemical MPO expression was investigated in placental samples of SLE women compared with normal controls.

MATERIALS AND METHODS

Ten patients with SLE were recruited as case group. Control group was selected from mothers with normal uncomplicated pregnancies. A monoclonal antibody specific for MPO was used for immunohistochemical staining and then the staining was quantified and differences between groups were compared using Mann-Whitney U test.

RESULTS

There were significant differences in the expression levels of MPO in the syncytiotrophoblast cells and the extravillous trophoblast cells between the control and SLE groups (p < 0.05). There were no significant differences in the expression level of MPO in the vascular endothelium and the relative number of the MPO-positive leukocytes in placental tissue between SLE and control groups (p > 0.05).

CONCLUSION

The present study showed that MPO expression is increased in syncytiotrophoblast cells and the extravillous trophoblast cells of SLE placentas compared to healthy subjects. It seems that these changes are able to impress structure and function of placenta and survival of the fetus.

Mid-pregnancy circulating immune biomarkers in women with preeclampsia and normotensive controls

OBJECTIVES

To determine if mid-pregnancy circulating immune biomarkers are associated with preeclampsia.

STUDY DESIGN

Nested case-control study of 410 preeclamptic women and 297 normotensive controls with primiparous singleton pregnancies enrolled in the Danish National Birth Cohort. The mean gestational age in our cohort is 16 weeks (range 9-26).

MAIN OUTCOME MEASURES

Preeclampsia was defined by blood pressure ⩾140/90 mmHg and proteinuria ⩾3 g/24 h. Serum immune biomarkers included interleukin (IL)-6, IL-6 receptor, IL-4, IL-4 receptor, IL-5, IL-12, IL-2, TNF-α, TNF-β, TNF-receptor, IL-1β, IL-1α, IL-8, IL-10, IFN-γ, IL-18, macrophage migration inhibitory factor, macrophage inflammatory protein, transforming growth factor-beta (TGF-β), and RANTES. Associations with preeclampsia, term preeclampsia and preterm preeclampsia were determined using two logistic regression models; (1) biomarkers were dichotomized by the limit of detection (LOD); (2) on the continuous scale, non-detectable values were imputed by LOD/2 and transformed (base 2). All models were adjusted for body mass index and smoking.

RESULTS

IL1β was significantly associated with a decrease in the log odds of preeclampsia (p=0.0065), term preeclampsia (p=0.0230) and preterm preeclampsia (p=0.0068). Results were similar for IL4r and preeclampsia (p=0.0383). In the dichotomized models, detectable TNF-β was significantly associated with preeclampsia (ORadj 1.6, 95% CI 1.1-2.3) and term preeclampsia (OR 1.7, 95% CI 1.1-2.5) but not preterm preeclampsia. Detectable IL6 was significantly with term preeclampsia only (OR 1.5, 95% CI 1.1-2.2).

CONCLUSION

Mid-pregnancy circulating IL1β, IL4r, IL6, and TNFβ were associated with preeclampsia. However, results were not consistent across statistical models. As the relationship is complex, future studies should explore cytokine clusters in preeclampsia risk.

Vitamin D3 alters Toll-like receptor 4 signaling in monocytes of pregnant women at risk for preeclampsia

Vitamin D deficiency during pregnancy is thought to play a role in the development of preeclampsia; however, the underlying mechanism is not fully understood. In this study, a randomized double-blind placebo-controlled clinical trial was performed among 60 pregnant women at risk for pre-eclampsia according to abnormal uterine artery Doppler waveform. Subjects were randomly divided into 2 groups to receive a daily dose of 2000 IU vitamin D3 supplements (n=30) or receive placebo (n=30) between gestational weeks 20-32 for a total of 12 consecutive weeks. Because vitamin D3 supplementation can induce anti-inflammatory cytokine signaling, peripheral blood monocytes were investigated by flow cytometry for expression of toll-like receptor 4 (TLR4), an important mediator of innate immune response. The pro-inflammatory cytokines secretion of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1 from monocytes, which are typically upregulated in preeclampsia, was also assessed. The incidence of preeclampsia was significantly lower in patients treated with vitamin D3 compared to the placebo group. Both the mean fluorescence intensity and the positive percentage of monocytes TLR4 in the vitamin D group were significantly lower compared to the placebo group, as well as the concentrations of secreted TNF-α, IL-6, and IL-1, while the concentration of IL-10 was higher. In the placebo group, the positive frequency of monocytes TLR4 was negatively correlated with the concentration of serum 25-hydroxyvitamin D in preeclampsia patients. Based on these results, we conclude that vitamin D3 supplementation for patients at risk of preeclampsia leads to a decrease in the expression of peripheral blood monocytes TLR4 and a subsequent decrease in pro-inflammatory cytokine secretion. Therefore, inhibiting the expression of monocytes TLR4 through vitamin D3 supplement may be a new approach to preeclampsia prevention.

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.

Four Pathways Involving Innate Immunity in the Pathogenesis of Preeclampsia

The maternal innate immune system plays an important role both in normal pregnancy as well as hypertensive disorders of pregnancy including preeclampsia (PE). We propose four pathways that involve excessive innate immunity that lead to most forms of PE. Pre-existing endothelial dysfunction plus pregnancy leads to an excessive innate immune response resulting in widespread inflammation, placental and renal dysfunction, vasoconstriction, and PE. Placental dysfunction due to shallow trophoblast invasion, inadequate spiral artery remodeling, and/or low placental perfusion initiates an innate immune response leading to excessive inflammation, endothelial and renal dysfunction, and PE. A heightened innate immune system due to pre-existing or acquired infections plus the presence of a paternally derived placenta and semi-allogeneic fetus cause an excessive innate immune response which manifests as PE. Lastly, an abnormal and excessive maternal immune response to pregnancy leads to widespread inflammation, organ dysfunction, and PE. We discuss the potential role of innate immunity in each of these scenarios, as well as the overlap, and how targeting the innate immune system might lead to therapies for the treatment of PE.

Oxidation of placental insulin and insulin-like growth factor receptors in mothers with diabetes mellitus or preeclampsia complicated with intrauterine growth restriction

Placental insulin receptor (IR) and insulin-like growth factor receptors (IGFRs) are essential for fetal growth. We investigated structural changes of these receptors exposed to increased oxidative stress in mothers diagnosed with diabetes mellitus (DM) or preeclampsia (PE) complicated with intrauterine growth restriction. Increased amount of IR and decreased amounts of IGF1R and IGF2R were found in both pathologies, accompanied by significant elevation in protein carbonyls. When isolated receptors were examined, increased carbonylation of IR and IGF1R in PE placentas was detected, whereas the amounts of carbonylated IR and IGF1R were similar in DM and healthy placentas. Carbonylation status of IGF2R did not change due to pathology, confirming the detrimental role of primary structure and conformation in oxidative susceptibility. Ligand binding was similar in all three groups of samples and did not seem to be affected by receptor oxidation. Since babies delivered by mothers with PE were smaller than the referent population, increased carbonylation of receptors might have affected downstream receptor signaling post-ligand binding.

Molecular mechanisms of maternal vascular dysfunction in preeclampsia

In preeclampsia, as a heterogeneous syndrome, multiple pathways have been proposed for both the causal as well as the perpetuating factors leading to maternal vascular dysfunction. Postulated mechanisms include imbalance in the bioavailability and activity of endothelium-derived contracting and relaxing factors and oxidative stress. Studies have shown that placenta-derived factors [antiangiogenic factors, microparticles (MPs), cell-free nucleic acids] are released into the maternal circulation and act on the vascular wall to modify the secretory capacity of endothelial cells and alter the responsiveness of vascular smooth muscle cells to constricting and relaxing stimuli. These molecules signal their deleterious effects on the maternal vascular wall via pathways that provide the molecular basis for novel and effective therapeutic interventions.

Pre-eclampsia renamed and reframed: Intra-abdominal hypertension in pregnancy

This hypothesis proposes pre-eclampsia is caused by intra-abdominal hypertension in pregnancy. Sustained or increasing intra-abdominal pressure ⩾12mmHg causes impaired venous return to the heart, systemic vascular resistance, ischemia reperfusion injury, intestinal permeability, translocation of lipopolysaccharide endotoxin to the liver, cytotoxic immune response, systemic inflammatory response, pressure transmission to thoracic and intra-cranial compartments, and multi-organ dysfunction. This hypothesis is predicated on Pascal's law, evidence founded in the intra-abdominal hypertension literature, and the adapted equation ΔIAP-P=ΔIAVF/Cab, where ΔIAP-P=change in intra-abdominal pressure in pregnancy, ΔIAVF=change in intra-abdominal vector force (volume and force direction) and Cab=abdominal compliance. Factors causing increased intra-abdominal pressure in pregnancy include: progressive uterine expansion, obstetrical factors that increase intra-uterine volume excessively or acutely, maternal anthropometric measurements that affect intra-abdominal pressure thresholds, maternal postures that increase abdominal force direction, abdominal compliance that is decreased, diminished with advancing gestation, or has reached maximum expansion, habitation at high altitude, and rapid drops in barometric pressure. We postulate that the threshold for lipopolysaccharide translocation depends on the magnitude of intra-abdominal pressure, the intestinal microbiome complex, and the degree of intestinal permeability. We advance that delivery cures pre-eclampsia through the mechanism of abdominal decompression.

Relationship between maternal immunological response during pregnancy and onset of preeclampsia

Maternofetal immune tolerance is essential to maintain pregnancy. The maternal immunological tolerance to the semiallogeneic fetus becomes greater in egg donation pregnancies with unrelated donors as the complete fetal genome is allogeneic to the mother. Instead of being rejected, the allogeneic fetus is tolerated by the pregnant woman in egg donation pregnancies. It has been reported that maternal morbidity during egg donation pregnancies is higher as compared with spontaneous or in vitro fertilization pregnancies. Particularly, egg donation pregnancies are associated with a higher incidence of pregnancy-induced hypertension and placental pathology. Preeclampsia, a pregnancy-specific disease characterized by the development of both hypertension and proteinuria, remains the leading cause of maternal and perinatal mortality and morbidity. The aim of this review is to characterize and relate the maternofetal immunological tolerance phenomenon during pregnancies with a semiallogenic fetus, which are the spontaneously conceived pregnancies and in vitro fertilization pregnancies, and those with an allogeneic fetus or egg donation pregnancies. Maternofetal immune tolerance in uncomplicated pregnancies and pathological pregnancies, such as those with preeclampsia, has also been assessed. Moreover, whether an inadequate maternal immunological response to the allogenic fetus could lead to a higher prevalence of preeclampsia in egg donation pregnancies has been addressed.

Possible regulatory role of Snail in NF-κB-mediated changes in E-cadherin in gastric cancer

In the present study, we aimed to investigate the involvement of Snail in NF-κB-mediated changes of E-cadherin in gastric cancer. A total of 189 human gastric cancer tissues, and 32 normal gastric mucosal tissues were used to determine the expression levels of NF-κB, E-cadherin and Snail by immunohistochemistry. The correlation between the expression levels and patient clinicopathological data was analyzed. Human gastric cancer cell line SGC7901 was treated with the NF-κB inhibitor PDTC, and the expression levels of E-cadherin and Snail were investigated by qPCR and western blot. NF-κB, E-cadherin and Snail were all detected in normal gastric mucosa and cancer tissues of various differentiation statuses. However, the expression patterns of each protein were different. Strong expression of E-cadherin was detected in normal gastric mucosa, whereas its expression gradually declined in gastric cancer tissues, with weak expression observed in poorly differentiated gastric cancer tissues. In contrast, weak NF-κB and Snail expressions were present in normal gastric mucosa, while their expression levels gradually increased in gastric cancer tissues, with the strongest expression detected in poorly differentiated gastric cancers. The expression of E-cadherin was inversely correlated with that of Snail and NF-κB in the tissues tested. Blockade of NF-κB using its inhibitor PDTC led to a time-dependent reduction in Snail but a time-dependent increase in E-cadherin in SGC7901 cells. These results suggest that in human gastric cancer, loss of E-cadherin may be mediated through NF-κB-induced Snail upregulation. Further studies may reveal whether targeting the NF-κB-Snail-E-cadherin axis could be a useful approach for combating gastric cancer.