IL-6: An endogenous activator of MMP-9 in preterm birth

Maternal genetic risk factors for spontaneous preterm birth: A systematic review and meta-analysis

BACKGROUND

Despite various genomic approaches used in prior studies investigating the association of maternal genetic variability with spontaneous preterm birth (sPTB), results show inconsistency and contradictions.

OBJECTIVES

To conduct a systematic review of studies analyzing the association between maternal genetic variants and sPTB, evaluate retrieved studies based on selection criteria, classify studies into hypothesis-based and hypothesis-free, and perform a meta-analysis to identify the strongest associations.

SEARCH STRATEGY

PubMed, Scopus, and reference lists were searched until October 2024.

SELECTION CRITERIA

English-language, case-control, cross-sectional, and prospective cohort studies examining the association between maternal genetic variations and sPTB were included.

DATA COLLECTION AND ANALYSIS

Data on authors, publication year, ethnicity, genes/variants, P values, study type, sample size, inclusion criteria, and methods were collected. The association strength was estimated using odds ratios with 95% confidence intervals.

RESULTS

Eighty-one studies met eligibility criteria: 73 utilized a hypothesis-based and 14 a hypothesis-free approach. Thirty-five studies qualified for a meta-analysis, revealing a significant association in tumor necrosis factor α (rs1800629) gene for alleles and additive and recessive genetic models (P ≤ 0.05). From the hypothesis-free approach, 13 genes reached global significance in association with sPTB (P < 5 × 10-8).

CONCLUSIONS

No single gene or variant was consistently associated with sPTB risk among studies. Hypothesis-based analyses highlighted tumor necrosis factor α (rs1800629) as a modest signal, while hypothesis-free approaches identified 13 genes with genome-wide significance, pointing to new research directions in understanding sPTB genetics.

The Impact of Amniotic Fluid Interleukin-6, Interleukin-8, and Metalloproteinase-9 on Preterm Labor: A Narrative Review

BACKGROUND/OBJECTIVES

Preterm labor is a leading cause of neonatal morbidity and mortality worldwide. Previous research has indicated that an inflammatory response or microbial invasion of the amniotic cavity is a pathological condition linked to preterm birth; hence, inflammatory markers such as metalloproteinase-9 (MMP-9), interleukin-6 (IL-6), and interleukin-8 (IL-8) have been utilized to predict preterm delivery. The identification of reliable biomarkers for early prediction is critical for improving maternal, fetal, and neonatal outcomes.

METHODS

To address this issue, a literature review has been conducted on PubMed/Medline and Scopus databases for articles investigating the possible correlation between IL6, IL8, and MMP9 and preterm labor.

RESULTS

Using a comprehensive search of the PubMed and Scopus databases, 12 studies were analyzed to identify the correlation between these biomarkers and preterm labor. Seven studies point the impact of increased IL-6 levels or polymorphisms of the gene and higher incidence of preterm labor. Two of the included studies identified the increased risk for preterm birth in elevated levels of IL-8 in amniotic fluid. Six studies highlight the increased incidence of preterm birth in women with polymorphisms of the MMP-9 gene.

CONCLUSIONS

Elevated IL-6 levels and specific gene polymorphisms are strongly associated with preterm delivery risk, with IL-8 concentrations correlating with systemic inflammation and histologic chorioamnionitis. MMP-9 gene variations and protein levels showed significant predictive value for membrane rupture and labor onset. The findings emphasize integrating these biomarkers into diagnostic tools for routine prenatal care, enhancing early detection, risk stratification, and timely interventions to improve maternal and neonatal outcomes.

Gestation-dependent increase in cervicovaginal pro-inflammatory cytokines and cervical extracellular matrix proteins is associated with spontaneous preterm delivery within 2 weeks of index assessment in South African women

Introduction

Inflammation-induced remodelling of gestational tissues that underpins spontaneous preterm birth (sPTB, delivery < 37 weeks' gestation) may vary by race and context. To explore relationships between markers of these pathological processes, we (a) characterised the cervicovaginal fluid (CVF) cytokine profiles of pregnant South African women at risk of PTB; (b) determined CVF matrix-metalloproteinase-9 (MMP-9) and its regulator tissue inhibitor of metalloproteinase-1 (TIMP-1); and (c) explored the predictive potential of these markers for sPTB.

Method of study

The concentrations of 10 inflammatory cytokines and MMP-9 and TIMP-1 were determined by ELISA in CVF samples from 47 non-labouring women at high risk of PTB. We studied CVF sampled at three gestational time points (GTPs): GTP1 (20-22 weeks, n = 37), GTP2 (26-28 weeks, n = 40), and GTP3 (34-36 weeks, n = 29) and analysed for changes in protein concentrations and predictive capacities (area under the ROC curve (AUC) and 95% confidence interval (CI)) for sPTB.

Results

There were 11 (GTP1), 13 (GTP2), and 6 (GTP3) women who delivered preterm within 85.3 ± 25.9, 51.3 ± 15.3, and 11.8 ± 7.5 (mean ± SD) days after assessment, respectively. At GTP1, IL-8 was higher (4-fold, p = 0.02), whereas GM-CSF was lower (~1.4-fold, p = 0.03) in the preterm compared with term women with an average AUC = 0.73. At GTP2, IL-1β (18-fold, p < 0.0001), IL-8 (4-fold, p = 0.03), MMP-9 (17-fold, p = 0.0007), MMP-9/TIMP-1 ratio (9-fold, p = 0.004), and MMP-9/GM-CSF ratio (87-fold, p = 0.005) were higher in preterm compared with term women with an average AUC = 0.80. By contrast, IL-10 was associated with term delivery with an AUC (95% CI) = 0.75 (0.55-0.90). At GTP3, IL-1β (58-fold, p = 0.0003), IL-8 (12-fold, p = 0.002), MMP-9 (296-fold, p = 0.03), and TIMP-1 (35-fold, p = 0.01) were higher in preterm compared with term women with an average AUC = 0.85. Elevated IL-1β was associated with delivery within 14 days of assessment with AUC = 0.85 (0.67-0.96). Overall, elevated MMP-9 at GTP3 had the highest (13.3) positive likelihood ratio for distinguishing women at risk of sPTB. Lastly, a positive correlation between MMP-9 and TIMP-1 at all GTPs (ρ ≥ 0.61, p < 0.01) for women delivering at term was only observed at GTP1 for those who delivered preterm (ρ = 0.70, p < 0.03).

Conclusions

In this cohort, sPTB is associated with gestation-dependent increase in pro-inflammatory cytokines, decreased IL-10 and GM-CSF, and dysregulated MMP-9-TIMP-1 interaction. Levels of cytokine (especially IL-1β) and ECM remodelling proteins rise significantly in the final 2 weeks before the onset of labour when sPTB is imminent. The signalling mechanisms for these ECM remodelling observations remain to be elucidated.

Recent Advances and Challenges in the Early Diagnosis and Treatment of Preterm Labor

Preterm birth (PTB) is the primary cause of neonatal mortality and long-term disabilities. The unknown mechanism behind PTB makes diagnosis difficult, yet early detection is necessary for controlling and averting related consequences. The primary focus of this work is to provide an overview of the known risk factors associated with preterm labor and the conventional and advanced procedures for early detection of PTB, including multi-omics and artificial intelligence/machine learning (AI/ML)- based approaches. It also discusses the principles of detecting various proteomic biomarkers based on lateral flow immunoassay and microfluidic chips, along with the commercially available point-of-care testing (POCT) devices and associated challenges. After briefing the therapeutic and preventive measures of PTB, this review summarizes with an outlook.

Comprehensive Analysis of the Role of Gene Variants in Matrix Metalloproteinases and Their Tissue Inhibitors in Retinopathy of Prematurity: A Study in the Polish Population

This study was designed to investigate the relationship between variants of matrix metalloproteinases (MMP-1 rs179975, MMP-9 rs17576 and rs17577), their tissue inhibitors (TIMP-1 rs4898, TIMP-2 rs2277698 and rs55743137) and the development of retinopathy of prematurity (ROP) in infants from the Polish population. A cohort of 100 premature infants (47% female) was enrolled, including 50 ROP cases and 50 no-ROP controls. Patients with ROP were divided into those with spontaneous remission and those requiring treatment. A positive association between MMP-1 rs179975 1G deletion allele and ROP was observed in the log-additive model (OR = 5.01; p = 0.048). Furthermore, female neonates were observed to have a negative association between the TIMP-1 rs4898C allele and the occurrence of ROP and ROP requiring treatment (codominant models with respective p-values < 0.05 and 0.043). Two and three loci interactions between MMP-1 rs1799750 and TIMP1rs4989 (p = 0.015), as well as MMP-1 rs1799750, MMP-9 rs17576 and TIMP-1 rs4989 (p = 0.0003) variants influencing the ROP risk were also observed. In conclusion, these findings suggest a potential role of MMPs and TIMPs genetic variations in the development of ROP in the Polish population. Further studies using a larger group of premature infants will be required for validation.

Predicting the Risk of Preterm Birth Throughout Pregnancy Based on a Novel Transcriptomic Signature

Objective

This study focused on the prediction of preterm birth (PTB). It aimed to identify the transcriptomic signature essential for the occurrence of PTB and evaluate its predictive value in early, mid, and late pregnancy and in women with threatened preterm labor (TPTL).

Methods

Blood transcriptome data of pregnant women were obtained from the Gene Expression Omnibus database. The activity of biological signatures was assessed using gene set enrichment analysis and single-sample gene set enrichment analysis. The correlation among molecules in the interleukin 6 (IL6) signature and between IL6 signaling activity and the gestational week of delivery and latent period were evaluated by Pearson correlation analysis. The effects of molecules associated with the IL6 signature were fitted using logistic regression analysis; the predictive value of both the IL6 signature and IL6 alone were evaluated using receiver operating characteristic curves and pregnancy maintenance probability was assessed using Kaplan-Meier analysis. Differential analysis was performed using the DEseq2 and limma algorithms.

Results

Circulatory IL6 signaling activity increased significantly in cases with preterm labor than in those with term pregnancies (normalized enrichment score (NES) = 1.857, P = 0.001). The IL6 signature (on which IL6 signaling is based) was subsequently considered as the candidate biomarker for PTB. The area under the curve (AUC) values for PTB prediction (using the IL6 signature) in early, mid, and late pregnancy were 0.810, 0.695, and 0.779, respectively; these values were considerably higher than those for IL6 alone. In addition, the pregnancy curves of women with abnormal IL6 signature differed significantly from those with normal signature. In pregnant women who eventually had preterm deliveries, circulatory IL6 signaling activity was lower in early pregnancy (NES = -1.420, P = 0.031) and higher than normal in mid (NES = 1.671, P = 0.002) and late pregnancy (NES = 2.350, P < 0.001). In women with TPTL, the AUC values for PTB prediction (or PTB within 7 days and 48 hours) using the IL6 signature were 0.761, 0.829, and 0.836, respectively; the up-regulation of IL6 signaling activity and its correlation with the gestational week of delivery (r = -0.260, P = 0.001) and latency period (r = -0.203, P = 0.012) were more significant than in other women.

Conclusion

Our findings suggest that the IL6 signature may predict PTB, even in early pregnancy (although the predictive power is relatively weak in mid pregnancy) and is particularly effective in symptomatic women. These findings may contribute to the development of an effective predictive and monitoring system for PTB, thereby reducing maternal and fetal risk.

Glioma-associated microglia/macrophages (GAMs) in glioblastoma: Immune function in the tumor microenvironment and implications for immunotherapy

Glioma is a mixed solid tumor composed of neoplastic and non-neoplastic components. Glioma-associated macrophages and microglia (GAMs) are crucial elements of the glioma tumor microenvironment (TME), regulating tumor growth, invasion, and recurrence. GAMs are also profoundly influenced by glioma cells. Recent studies have revealed the intricate relationship between TME and GAMs. In this updated review, we provide an overview of the interaction between glioma TME and GAMs based on previous studies. We also summarize a series of immunotherapies targeting GAMs, including clinical trials and preclinical studies. Specifically, we discuss the origin of microglia in the central nervous system and the recruitment of GAMs in the glioma background. We also cover the mechanisms through which GAMs regulate various processes associated with glioma development, such as invasiveness, angiogenesis, immunosuppression, recurrence, etc. Overall, GAMs play a significant role in the tumor biology of glioma, and a better understanding of the interaction between GAMs and glioma could catalyze the development of new and effective immunotherapies for this deadly malignancy.

The landscape of circular RNA in preterm birth

Background

Preterm birth (PTB) is a multifactorial syndrome that seriously threatens the health of pregnant women and babies worldwide. Recently, circular RNAs (circRNAs) have been understood as important regulators of various physiological and pathological processes. However, the expression pattern and potential roles of circRNAs in PTB are largely unclear.

Methods

In this study, we extracted and analyzed the circRNA expression profiles in maternal and fetal samples of preterm and term pregnancies, including maternal plasma, maternal monocytes, myometrium, chorion, placenta, and cord blood. We identified the circRNAs which is associated with PTB in different tissues and explored their relationships from the perspective of the overall maternal-fetal system. Furthermore, co-expression analysis of circRNAs and mRNAs, target microRNAs (miRNAs), and RNA-binding proteins (RBPs), provided new clues about possible mechanisms of circRNA function in PTB. In the end, we investigated the potential special biofunctions of circRNAs in different tissues and their common features and communication in PTB.

Results

Significant differences in circRNA types and expression levels between preterm and term groups have been proved, as well as between tissues. Nevertheless, there were still some PTB-related differentially expressed circRNAs (DECs) shared by these tissues. The functional enrichment analysis showed that the DECs putatively have important tissue-specific biofunctions through their target miRNA and co-expressed mRNAs, which contribute to the signature pathologic changes of each tissue within the maternal-fetal system in PTB (e.g., the contraction of the myometrium). Moreover, DECs in different tissues might have some common biological activities, which are mainly the activation of immune-inflammatory processes (e.g., interleukin1/6/8/17, chemokine, TLRs, and complement).

Conclusions

In summary, our data provide a preliminary blueprint for the expression and possible roles of circRNAs in PTB, which lays the foundation for future research on the mechanisms of circRNAs in PTB.

Systematic review of preterm birth multi-omic biomarker studies

Preterm birth (PTB) is one of the leading causes of deaths in infants under the age of five. Known risk factors of PTB include genetic factors, lifestyle choices or infection. Identification of omic biomarkers associated with PTB could aid clinical management of women at high risk of early labour and thereby reduce neonatal morbidity. This systematic literature review aimed to identify and summarise maternal omic and multi-omic (genomics, transcriptomics, proteomics and metabolites) biomarker studies of PTB. Original research articles were retrieved from three databases: PubMed, Web of Science and Science Direct, using specified search terms for each omic discipline. PTB studies investigating genomics, transcriptomics, proteomics or metabolomics biomarkers prior to onset of labour were included. Data were collected and reviewed independently. Pathway analyses were completed on the biomarkers from non-targeted omic studies using Reactome pathway analysis tool. A total of 149 omic studies were identified; most of the literature investigated proteomic biomarkers. Pathway analysis identified several cellular processes associated with the omic biomarkers reported in the literature. Study heterogeneity was observed across the research articles, including the use of different gestation cut-offs to define PTB. Infection/inflammatory biomarkers were identified across majority of papers using a range of targeted and non-targeted approaches.

Downregulation of miR-21 is Involved in the Pathogenesis of Infection-Induced Preterm Birth by Targeting NF-κB

Infection-induced preterm birth (PTB) is contributing to the main factors of increased maternal and fetal morbidity and mortality. Infections and inflammation are often accompanied by histologic chorioamnionitis. Recently, several studies have uncovered that miR-21 and NF-κB are associated with pathological processes of pregnant women. However, the role of miR-21 in infection-induced PTB remains unclear. This study aimed to determine whether miR-21 is involved in the pathogenesis of infection-induced PTB by regulating NF-κB. In this study, we found that the expression of miR-21 was significantly decreased in placental tissues of lipopolysaccharides (LPS)-induced infectious PTB mice model, accompanied by the increase of NF-κB, IL-6, and TNF-α (P < 0.05). Luciferase reporter gene assays showed that NF-κB was a validated target of miR-21. Furthermore, cell transfection experiments showed that miR-21 overexpression significantly decreased NF-κB mRNA expression compared with the miR-control group and blank group. Conversely, miR-21 inhibitor can enhance NF-κB mRNA expression. After the treatment of miR-21 mimics, miR-21 expression was obviously increased compared with the LPS group, accompanied by the decrease of NF-κB, TNF-α, and IL-6 mRNA expression (P < 0.05). What's more, miR-21 expression was negatively correlated with NF-κB (r=-0.87, P < 0.01). Overall, the study findings indicate that miR-21 may contribute to the pathogenesis of infection-induced PTB by upregulating the target NF-κB and that miR-21 may be a new potential therapeutic target for infection-induced PTB.