The role of inflammatory biomarkers in the development and progression of pre-eclampsia: a systematic review and meta-analysis

Maternal Immune Activation During Pregnancy and Obstetric Outcomes: A Population-Based Cohort Study

OBJECTIVE

Maternal immune activation has been proposed as a mechanism for adverse pregnancy outcomes, yet the mechanisms and effects of timing remain unclear. Immune disruption in early gestation may be particularly detrimental as this is an important period for placental development, which has been associated with the pathology of adverse obstetric outcomes. To increase our understanding of risk factors for adverse obstetric outcomes, we aim to investigate the association between multiple inflammatory and angiogenic markers during early pregnancy and adverse pregnancy outcomes in a large population-based cohort.

DESIGN

Prospective population-based pregnancy cohort study (n = 7513).

SETTING

Rotterdam, the Netherlands.

POPULATION

Pregnant women in Rotterdam between April 2002 and January 2006.

METHODS

Serum inflammatory markers (high-sensitivity (HS)-C-reactive protein (CRP), interleukin (IL)-1β, IL-6, IL-17a, IL-23, interferon (IFN)-γ) and angiogenic factors (sFlt-1 and PlGF) were analysed in repeated measures around 13-20 weeks gestation. A cytokine index was created using principal component analysis.

MAIN OUTCOME MEASURES

Hypertensive disorders of pregnancy, spontaneous preterm birth and small for gestational age at birth.

RESULTS

HS-CRP, but not the cytokine index, was associated with increased risk of spontaneous preterm birth after multiple testing correction. We found no association of HS-CRP or the cytokine index with hypertensive disorders of pregnancy and small for gestational age at birth after multiple testing correction. Inflammatory and angiogenic factors were associated with each other, yet effect sizes were small.

CONCLUSIONS

We found no strong evidence of a link between early gestation typical inflammatory marker levels and the risk of adverse pregnancy outcomes.

The Impact of Inflammatory Cytokines on Recurrent Pregnancy Loss: A Preliminary Investigation

Recurrent pregnancy loss (RPL), defined as two or more consecutive miscarriages before 20 weeks of gestation, affects 1-2% of couples worldwide. Pro-inflammatory cytokines, such as TNF-α, IL-1β and IL-6 play critical roles in early pregnancy, while anti-inflammatory cytokines like TGF-β and IL-10 promote immune tolerance to prevent harmful inflammatory responses that play important role in placental and fetal development. This aim of the study is to analyse the levels of inflammatory cytokines in blood serum from RPL patients and healthy women (control). The measured cytokines included TNF-α, IL-6, IL-10, TGF-β, CRP, ferritin, IL-1β and IL-4, IFN-γ and IL-17. Using an unpaired t-test and Pearson correlation, significant difference observed between the groups. The results had significantly elevated CRP levels with decreased levels of TGF-β and ferritin (p < 0.05), whereas, IL-1β and IL-4 also found raised indicating a link between systemic inflammation and recurrent miscarriages. IL-4 and CRP increase further suggest potential oxidative stress role in RPL cases. However, no significant differences observed in IL-10, IL-6, or TNF-α level between the groups. This study highlights immune dysregulation as possible contributors to early pregnancy loss, with significant increases in CRP, IL-1β, and IL-4 levels indicating an imbalanced immune response at the maternal-fetal interface. These cytokine elevations may disrupt immune tolerance, suggesting the need for further exploration into cytokine interactions in pregnancy and their potential as an investigatory biomarker and therapeutic target in RPL.

Evaluation of Platelet Indices and Inflammation Markers in Preeclampsia

Background: Preeclampsia is a serious pregnancy complication known to be related to the pathophysiology of platelet dysfunction and inflammation. The aim of this study was to investigate the role of platelet indices and inflammatory markers in preeclampsia and their importance in predicting adverse neonatal outcomes. Methods: A total of 118 preeclampsia cases (84 with mild preeclampsia and 34 with severe preeclampsia) and 118 healthy pregnant women were included in the study. Blood samples obtained at the time of preeclampsia diagnosis were analyzed for platelet indices (platelet count (PC), platelet distribution width (PDW), mean platelet volume (MPV), and platelet/large cell ratio (P-LCR)) and inflammation indices (neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), and mean platelet volume-to-lymphocyte ratio (MPVLR)). Results: The PC and PLR were lower in the severe preeclampsia group compared to the other groups. The PDW was higher in both mild and severe preeclampsia groups compared to the control group. A PDW value above 13.15 was identified as a significant predictor of composite adverse neonatal outcomes (area under the curve (AUC): 0.633; sensitivity: 60.9%; specificity: 58%). Conclusions: PC and PLR decrease in severe preeclampsia. This study highlights the potential of PDW as a marker for predicting adverse neonatal outcomes in preeclampsia.

Predictivity of Hepatic Steatosis Index for Gestational Hypertension and Preeclampsia: a Prospective Cohort Study

Context: Previous studies have reported that pregnant women with non-alcoholic fatty liver disease (NAFLD) face an increased risk of gestational hypertension (GH) and preeclampsia (PE). However, no study has assessed the relationship between the Hepatic Steatosis Index (HSI), a biomarker for NAFLD, in early pregnancy and the subsequent risk of GH and PE. Objective: We aimed to investigate the relationship between HSI in early pregnancy and the risks of GH and PE in Chinese women. Methods: Based on the China Birth Cohort Study conducted from February 2018 to December 2022, this prospective cohort study collected liver enzyme and body mass index data from pregnant participants during 6-13+6 gestational weeks. The incidences of GH and PE were monitored until delivery. Results: This study included 39,114 pregnant women, and GH and PE incidences were 4.2% and 4.1%, respectively. After multivariable adjustment, the risks of GH (Q2: OR = 1.35, 95% CI = 1.13-1.62; Q3: OR = 1.86, 95% CI = 1.57-2.20; Q4: OR = 3.81, 95% CI = 3.25-4.46) and PE (Q2: OR = 1.22, 95% CI = 1.01-1.47; Q3: OR = 1.96, 95% CI = 1.65-2.32; Q4: OR = 3.60, 95% CI = 3.07-4.22) significantly increased with higher HSI quartiles. Further analysis indicated that compared to women aged 35 years or older, HSI in pregnant women under 35 years had relatively stronger predictive value for GH (OR ≥ 35 = 4.527, 95% CI = 3.762-5.446 vs. OR < 35 = 2.325, 95% CI = 1.729-3.128) and PE (OR ≥ 35 = 4.13, 95% CI = 3.433-4.983 vs. OR < 35 = 2.348, 95% CI = 1.736-3.176). Conclusion: Elevated HSI may be associated with an increased risk of GH and PE.

Can Global DNA Methylation Be Influenced by Polymorphisms in Genes Involved in Epigenetic Mechanisms? A Review

BACKGROUND

Global methylation refers to the total methylation in the DNA and can also be inferred from the Line 1 and Alu regions, as these repeats are very abundant in the genome. The main function of DNA methylation is to control gene expression and is associated with both normal and pathological mechanisms. DNA methylation depends on enzymes that generate the methyl radical (e.g., methylenetetrahydrofolate reductase-MTHFR) and attach this radical to the DNA (DNA methyltransferases-DNMT). Genetic variants such as single nucleotide polymorphisms (SNP) in these genes can lead to changes in the activity or expression of MTHFR and DNMT proteins and consequently influence the DNA methylation profile. This review focuses on studies investigating inter-individual variations in the global DNA methylation profile associated with genetic polymorphisms in the MTHFR and DNMT genes.

METHODS

A narrative review was conducted, taking into account articles published in the last 15 years.

RESULTS

It was found that the SNPs rs1801131, rs1801133 and rs1537514 in the MTHFR gene, rs2241531, rs2228611, rs2228612, rs21124724 and the haplotype rs2288349, rs2228611, rs2228612, rs16999593 in the DNMT1 gene, rs2424909, rs998382, rs6058891, rs6058897, rs4911256, rs2889703 and rs1883729 in the DNMT3B were associated with the level of global DNA methylation, including LINE and Alu regions in different contexts. No association was found with polymorphisms in the DNMT3A gene.

CONCLUSIONS

It is concluded that polymorphisms in the MTHFR and DNMT genes may influence the global DNA methylation profile in health, inflammation, tumours and mental illness.

The Hidden Relationship between Intestinal Microbiota and Immunological Modifications in Preeclampsia Pathogenesis

Preeclampsia is a multifactorial gestational syndrome characterized by increased blood pressure during pregnancy associated with multiorgan involvement. The impact of this disease on maternal and neonatal health is significant, as it can lead to various fetal comorbidities and contribute to the development of maternal comorbidities later in life. Consistent evidence has shown that the microbiota acts as a regulator of the immune system, and it may, therefore, influence the development of preeclampsia by modulating immune factors. This narrative review aims to investigate the role of the immune system in the pathogenesis of preeclampsia and to summarize the most recent literature on the possible link between preeclampsia and alterations in the intestinal microbiota. To this end, we conducted a literature search, aiming to perform a narrative review, on PubMed and Embase from January 1990 to March 2024, focusing on the latest studies that highlight the main differences in microbial composition between patients with and without preeclampsia, as well as the effects of microbial metabolites on the immune system. From the review of 28 studies assessing the intestinal microbiota in preeclamptic women, preeclampsia could be associated with a state of dysbiosis. Moreover, these patients showed higher plasmatic levels of endotoxin, pro-inflammatory cytokines, and T helper 17 cells; however, the findings on specific microbes and metabolites that could cause immune imbalances in preeclampsia are still preliminary.

Raised levels of chemerin in women with preeclampsia: A meta-analysis

Chemerin is a multifunctional adipokine associated with systemic inflammation, angiogenesis, and oxidative stress. Emerging evidence suggests a potential link between chemerin and the pathogenesis of preeclampsia (PE). In this systematic review and meta-analysis, we aimed to evaluate the serum chemerin levels in women with PE. A systematic search was conducted across Medline, Web of Science, and Embase databases from inception until April 15, 2023, to identify studies comparing serum chemerin levels in pregnant women with and without PE. A random-effects model was employed to pool the results, accounting for heterogeneity. Thirteen datasets from 10 observational studies, encompassing 832 women with PE and 1298 healthy pregnant women, were analyzed. The pooled findings indicated a statistically significant elevation in serum chemerin levels in women with PE compared to controls (mean difference [MD] = 89.56 ng/mL, 95% confidence interval [CI] 62.14 - 116.98; P < 0.001; I2 = 87%). The subgroup analysis revealed consistent findings across studies that measured chemerin levels before or after the diagnosis of PE, studies that did or did not match the body mass index (BMI), and studies with varying quality scores (P values for subgroup differences were all > 0.05). Compared to controls, women with severe PE exhibited a significantly greater increase in serum chemerin levels than those with mild PE (P value for subgroup difference = 0.007). Additionally, meta-regression analysis results suggested that the mean BMI of the included pregnant women might positively modify the difference in circulating chemerin levels between women with and without PE (coefficient = 8.92; P = 0.045). In conclusion, this meta-analysis suggests a positive correlation between elevated serum chemerin levels and PE diagnosis in comparison to pregnant women without the condition.

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.

Phthalate exposure increases interferon-γ during pregnancy: The Atlanta African American Maternal-Child Cohort

BACKGROUND

The immune system undergoes unique adaptations during pregnancy and is particularly sensitive to environmental chemicals, such as phthalates, which are associated with acute and chronic inflammatory medical conditions. However, current knowledge of how phthalate exposures are associated with systemic inflammation in pregnant people is limited by cross-sectional study designs and single chemical models. Our objective was to estimate the association between repeated measures of prenatal phthalate exposures, examined individually and collectively, and a panel of clinical inflammatory biomarkers.

METHODS

In the Atlanta African American Maternal-Child Cohort, biospecimens were collected at mean 11 and 26 weeks gestation (N = 126). Concentrations of eight urinary phthalate metabolites and five serum inflammatory biomarkers, including CRP, IFN-γ, IL-6, IL-10, and TNF-α, were measured. Linear mixed effect regression and quantile g-computation models were used to estimate the associations for single phthalates and their exposure mixture, respectively.

RESULTS

Participants who self-reported any use of alcohol, tobacco, or marijuana in the month prior to pregnancy had increased MEP, MBP, MiBP, and CRP, relative to those with no substance use. IFN-γ was elevated in response to MECPP (% change = 17.35, 95 % confidence interval [CI] = 0.32, 32.27), MEHHP (% change = 12.75, 95 % CI = 2.22, 24.36), MEOHP (% change = 11.63, 95 % CI = 1.21, 23.12), and their parent phthalate, ΣDEHP (% change = 15.03, 95 % CI = 0.28, 31.94). The phthalate mixture was also associated with an increase in IFN-γ (% change = 15.03, 95 % CI = 6.18, 24.61).

CONCLUSIONS

Our findings suggest DEHP metabolites induce systemic inflammation during pregnancy. The pro-inflammatory cytokine IFN-γ may play an important role in the relationship between prenatal phthalate exposures and adverse pregnancy outcomes.

Identification of gene signature markers in gestational hypertension and early-onset pre-eclampsia

INTRODUCTION

Hypertensive disorders in pregnancy (HDP) are the leading cause of perinatal mortality worldwide. Inflammatory responses induced by insufficient placental perfusion have become a focal point in understanding the pathogenesis and aetiology of HDP and developing reliable and consistent biomarkers. Therefore, this study aims to identify gene signatures linked to the pathophysiology of HDP (gestational hypertension and early and late-onset pre-eclampsia).

METHODS

RNA was extracted from the maternal serum from the blood samples collected from different groups of HDP patients. A multiplex inflammation panel (255 inflammatory and housekeeping genes) and further gene expression analysis using NanoString Digital Direct Detection were done. The prominent expressions of these genes were further validated through qPCR techniques.

RESULTS

NanoString analysis identified nine unique, significantly expressed genes (MAPK1, MAPK3, MAFF, HLA-DRA, IL12B, RHOA, MASP2, MEF2A and NR3C1) between specific group comparisons of different HPD classes and the normotensive groups. The qPCR showed that the HLA-DRA gene was significantly upregulated in the early-onset pre-eclamptic and gestational hypertensive group compared to its respective normotensive group. In contrast, MAFF and MEF2A were significantly downregulated in both HDPs compared to their controls. The MAPK1 gene was significantly higher in the early-onset group compared to the gestational hypertensive and normotensive groups.

DISCUSSION

The upregulation of these distinctive genes in hypertensive groups compared to normotensives confirmed their diagnostic potential. Therefore, HLA-DRA, MAFF and MEF2A could be candidate markers of HDP, while the MAPK1 gene could be a differentiating marker between early-onset pre-eclampsia and gestational hypertension.

Role of neutrophil / lymphocyte ratio, uric acid / albumin ratio and uric acid / creatinine ratio as predictors to severity of preeclampsia

BACKGROUND

Pre-eclampsia (PE) is an intractable obstetric disorder with high mortality and morbidity, affecting 6-8% of pregnancies worldwide. As its etiology and pathogenesis remain unclear, there are no specific prevention or treatment options. This study aimed to determine the association between neutrophil to lymphocyte ratio (NLR), uric acid to albumin ratio (UAR) and uric acid to creatinine ratio (UA/Cr) and severity of pre-eclampsia.

METHODS

A cross-sectional hospital-based study was conducted among pre-eclamptic women in Kosti Maternity Hospital from September to December 2022. Forty-five pre-eclamptic women were enrolled in this study and were classified according to the WHO classification of PE into mild PE (23 PE patients) and severe PE (22 PE patients). Data were collected using a semi-structured questionnaire covering medical history and clinical assessment. A blood sample was taken from each participant for measurements of the complete blood count (CBC), liver functions test (LFT) with enzymes, renal functions test (RFT) with electrolytes, and uric acid by standard techniques.

RESULTS

NLR was found to be statistically significantly higher in mothers with severe PE (6.3-9.9) than in those with mild PE (2.2-1.5) (p-value 0.048). Alanine aminotransferase (ALT) was significantly higher in women with severe PE than in those with mild PE (p-value = 0.02). The total means of platelet-lymphocyte ratio (PLR), UA/Cr, and UAR were insignificantly higher in women with severe PE compared with those with mild PE (p-values 0.666, 0.427, and 0.525, respectively). The means of uric acid and serum creatinine showed insignificant statistical elevation in women with severe PE compared with mild PE (p-values of 0.27 and 0.44, respectively). Serum albumin was found to be insignificantly lower in mothers with severe PE (3.3 ± 0.6 g/dl) than in those with mild PE (3.6 ± 0.6 g/dl); p-value = 0.21.

CONCLUSIONS

PE showed a significant statistical increase in WBC, neutrophils, alanine transaminase (ALT), and NLR in severe PE compared to mild PE and a significant statistical decrease in lymphocyte count in severe PE compared to mild PE. The measurement of NLR may be a useful laboratory marker for predicting the severity of PE.

Potential Inflammatory Biomarkers for Major Depressive Disorder Related to Suicidal Behaviors: A Systematic Review

Major depressive disorder (MDD) is a highly prevalent psychiatric condition affecting an estimated 280 million individuals globally. Despite the occurrence of suicidal behaviors across various psychiatric conditions, MDD is distinctly associated with the highest risk of suicide attempts and death within this population. In this study, we focused on MDD to identify potential inflammatory biomarkers associated with suicidal risk, given the relationship between depressive states and suicidal ideation. Articles published before June 2023 were searched in PubMed, Embase, Web of Science, and the Cochrane Library to identify all relevant studies reporting blood inflammatory biomarkers in patients with MDD with suicide-related behaviors. Of 571 articles, 24 were included in this study. Overall, 43 significant biomarkers associated with MDD and suicide-related behaviors were identified. Our study provided compelling evidence of significant alterations in peripheral inflammatory factors in MDD patients with suicide-related behaviors, demonstrating the potential roles of interleukin (IL)-1β, IL-6, C-reactive protein, C-C motif chemokine ligand 2, and tumor necrosis factor-α as biomarkers. These findings underscore the intricate relationship between the inflammatory processes of these biomarkers and their interactions in MDD with suicidal risk.