Ubiquitin-Proteasome-Collagen (CUP) Pathway in Preterm Premature Rupture of Fetal Membranes

COL28 promotes proliferation, migration, and EMT of renal tubular epithelial cells

Type XXVIII collagen (COL28) is involved in cancer and lung fibrosis. COL28 polymorphisms and mutations might be involved in kidney fibrosis, but the exact role of COL28 in renal fibrosis is unknown. This study explored the function of COL28 in renal tubular cells by examining the expression of COL28 mRNA and the effects of COL28 overexpression in human tubular cells. COL28 mRNA expression and localization were observed in normal and fibrotic kidney tissues from humans and mice using real-time PCR, western blot, immunofluorescence, and immunohistochemistry. The consequences of COL28 overexpression on cell proliferation, migration, cell polarity, and epithelial-to-mesenchymal transition (EMT) induced by TGF-β1 were examined in human tubular HK-2 cells. COL28 expression was low in human normal renal tissues, mainly observed in the renal tubular epithelial cells and especially in proximal renal tubules. COL28 protein expression in human and mouse obstructive kidney disease was higher than in normal tissues (p < 0.05) and more significant in the UUO2-Week than the UUO1-Week group. The overexpression of COL28 promoted HK-2 cell proliferation and enhanced their migration ability (all p < 0.05). TGF-β1 (10 ng/ml) induced COL28 mRNA expression in HK-2 cells, decreased E-cadherin and increased α-SMA in the COL28-overexpression group compared with controls (p < 0.05). ZO-1 expression decreased while COL6 increased in the COL28-overexpression group compared with controls (p < 0.05). In conclusion, COL28 overexpression promotes the migration and proliferation of renal tubular epithelial cells. The EMT could also be involved. COL28 could be a therapeutic target against renal- fibrotic diseases.

The Role of Genetics in Preterm Birth

Preterm birth (PTB), defined as the birth of a child before 37 completed weeks gestation, affects approximately 11% of live births and is the leading cause of death in children under 5 years. PTB is a complex disease with multiple risk factors including genetic variation. Much research has aimed to establish the biological mechanisms underlying PTB often through identification of genetic markers for PTB risk. The objective of this review is to present a comprehensive and updated summary of the published data relating to the field of PTB genetics. A literature search in PubMed was conducted and English studies related to PTB genetics were included. Genetic studies have identified genes within inflammatory, immunological, tissue remodeling, endocrine, metabolic, and vascular pathways that may be involved in PTB. However, a substantial proportion of published data have been largely inconclusive and multiple studies had limited power to detect associations. On the contrary, a few large hypothesis-free approaches have identified and replicated multiple novel variants associated with PTB in different cohorts. Overall, attempts to predict PTB using single "-omics" datasets including genomic, transcriptomic, and epigenomic biomarkers have been mostly unsuccessful and have failed to translate to the clinical setting. Integration of data from multiple "-omics" datasets has yielded the most promising results.

Epigenetic modifications appear in the human placenta following anxiety and depression during pregnancy

INTRODUCTION

The future health of the offspring can be influenced by longstanding maternal anxiety and depression disorders during pregnancy. The present study aimed to explore the effect of psychiatric disorders during pregnancy on placental epigenetics.

METHODS

We measured DNA methylation patterns in term-placentas of women either suffering longstanding anxiety and depression symptoms (Index group, with overt symptoms), or a healthy population (Control, none/only mild symptoms). Whole genome DNA methylation profiling was performed using the TruSeq® Methyl Capture EPIC Library Prep Kit (Illumina, San Diego, CA, USA) for library preparation and NGS technology for genomic DNA sequencing.

RESULTS

The results of high-throughput DNA methylation analysis revealed that the Index group had differential DNA methylation at epigenome-wide significance (p < 0.05) in 226 genes in the placenta. Targeted enrichment analyses identified hypermethylation of genes associated with psychiatric disorders (BRINP1, PUM1), and ion homeostasis (COMMD1), among others. The ECM (extracellular matrix)-receptor interaction pathway was significantly dysregulated in the Index group compared to the Control. In addition, DNA methylation/mRNA integration analyses revealed that four genes with key roles in neurodevelopment and other important processes (EPB41L4B, BMPR2, KLHL18, and UBAP2) were dysregulated at both, DNA methylation and transcriptome levels in the Index group compared to Control.

DISCUSSION

The presented results increase our understanding of how maternal psychiatric disorders may affect the newborn through placental differential epigenome, suggesting DNA methylation status as a biomarker when aiming to design new preventive techniques and interventions.

Emerging role of toll-like receptors signaling and its regulators in preterm birth: a narrative review

INTRODUCTION

Despite intensive research, preterm birth (PTB) rates have not decreased significantly in recent years due to a lack of understanding of the underlying causes and insufficient treatment options for PTB. We are committed to finding promising biomarkers for the treatment of PTB.

METHODS

An extensive search of the literature was conducted with MEDLINE/PubMed, and in total, 151 studies were included and summarized in the present review.

RESULTS

Substantial evidence supports that the infection and/or inflammatory cascade associated with infection is an early event in PTB. Toll-like receptor (TLR) is a prominent pattern recognition receptor (PRR) found on both immune and non-immune cells, including fetal membrane cells. The activation of TLR downstream molecules, followed by TLR binding to its ligand, is critical for infection and inflammation, leading to the involvement of the TLR signaling pathway in PTB. TLR ligands are derived from microbial components and molecules released by damaged and dead cells. Particularly, TLR4 is an essential TLR because of its ability to recognize lipopolysaccharide (LPS). In this comprehensive overview, we discuss the role of TLR signaling in PTB, focus on numerous host-derived genetic and epigenetic regulators of the TLR signaling pathway, and cover ongoing research and prospective therapeutic options for treating PTB by inhibiting TLR signaling.

CONCLUSION

This is a critical topic because TLR-related molecules and mechanisms may enable obstetricians to better understand the physiological changes in PTB and develop new treatment and prevention strategies.

Identification of key pathways, genes and immune cell infiltration in hypoxia of high-altitude acclimatization via meta-analysis and integrated bioinformatics analysis

Background: For individuals acutely exposed to high-altitude regions, environmental hypobaric hypoxia induces several physiological or pathological responses, especially immune dysfunction. Therefore, hypoxia is a potentially life-threatening factor, which has closely related to high-altitude acclimatization. However, its specific molecular mechanism is still unclear. Methods: The four expression profiles about hypoxia and high altitude were downloaded from the Gene Expression Omnibus database in this study. Meta-analysis of GEO datasets was performed by NetworkAnalyst online tool. Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene ontology (GO) enrichment analysis, and visualization were performed using R (version 4.1.3) software, respectively. The CIBERSORT analysis was conducted on GSE46480 to examine immune cell infiltration. In addition, we experimentally verified the bioinformatics analysis with qRT-PCR. Results: The meta-analysis identified 358 differentially expressed genes (DEGs), with 209 upregulated and 149 downregulated. DEGs were mostly enriched in biological processes and pathways associated with hypoxia acclimatization at high altitudes, according to both GO and KEGG enrichment analyses. ERH, VBP1, BINP3L, TOMM5, PSMA4, and POLR2K were identified by taking intersections of the DEGs between meta-analysis and GSE46480 and verified by qRT-PCR experiments, which were inextricably linked to hypoxia. Immune infiltration analysis showed significant differences in immune cells between samples at sea level and high altitudes. Conclusion: Identifying the DEGs and pathways will improve our understanding of immune function during high-altitude hypoxia at a molecular level. Targeting hypoxia-sensitive pathways in immune cells is interesting in treating high-altitude sickness. This study provides support for further research on high-altitude acclimatization.

Comparison of DNA Methylation Changes Between the Gestation Period and the After-Delivery State: A Pilot Study of 10 Women

Background

Gestational adaptation occurs soon after fertilization and continues throughout pregnancy, whereas women return to a pre-pregnancy state after delivery and lactation. However, little is known about the role of DNA methylation in fine-tuning maternal physiology. Understanding the changes in DNA methylation during pregnancy is the first step in clarifying the association of diet, nutrition, and thromboembolism with the changes in DNA methylation. In this study, we investigated whether and how the DNA methylation pattern changes in the three trimesters and after delivery in ten uncomplicated pregnancies.

Results

DNA methylation was measured using a Human MethylationEPIC BeadChip. There were 14,018 cytosine-guanine dinucleotide (CpG) sites with statistically significant changes in DNA methylation over the four time periods (p < 0.001). Overall, DNA methylation after delivery was higher than that of the three trimesters (p < 0.001), with the protein ubiquitination pathway being the top canonical pathway involved. We classified the CpG sites into nine groups according to the changes in the three trimesters and found that 38.37% of CpG sites had DNA methylation changes during pregnancy, especially between the first and second trimesters.

Conclusion

DNA methylation pattern changes between trimesters, indicating possible involvement in maternal adaptation to pregnancy. Meanwhile, DNA methylation patterns during pregnancy and in the postpartum period were different, implying that puerperium repair may also function through DNA methylation mechanisms.

Role of epigenetics in parturition and preterm birth

Preterm birth occurs worldwide and is associated with high morbidity, mortality, and economic cost. Although several risk factors associated with parturition and preterm birth have been identified, mechanisms underlying this syndrome remain unclear, thereby limiting the implementation of interventions for prevention and management. Known triggers of preterm birth include conditions related to inflammatory and immunological pathways, as well as genetics and maternal history. Importantly, epigenetics, which is the study of heritable phenotypic changes that occur without alterations in the DNA sequence, may play a role in linking social and environmental risk factors for preterm birth. Epigenetic approaches to the study of preterm birth, including analyses of the effects of microRNAs, long non-coding RNAs, DNA methylation, and histone modification, have contributed to an improved understanding of the molecular bases of both term and preterm birth. Additionally, epigenetic modifications have been linked to factors already associated with preterm birth, including obesity and smoking. The prevention and management of preterm birth remains a challenge worldwide. Although epigenetic analysis provides valuable insights into the causes and risk factors associated with this syndrome, further studies are necessary to determine whether epigenetic approaches can be used routinely for the diagnosis, prevention, and management of preterm birth.

(Epi)genetic variants of the sarcomere-desmosome are associated with premature utero-contraction in spontaneous preterm labor

Spontaneous preterm birth is a syndrome with clinical and genetic heterogeneity. Few studies have focused on the genetic and epigenetic defects and pathogenic mechanisms associated with premature uterine contraction in spontaneous preterm birth. The objective of this study was to investigate the (epi)genetic variations associated with premature uterine contraction of spontaneous preterm birth. A systems biology approach with an integrated multiomic study was employed. Biobanked pregnancy tissues selected from a pregnancy cohort were subjected to genomic, transcriptomic, methylomic, and proteomic studies, with a focus on genetic loci/genes related to uterine muscle contraction, specifically, genes associated with sarcomeres and desmosomes. Thirteen single nucleotide variations and pathogenic variants were identified in the sarcomere gene, TTN, which encodes the protein Titin, from 146 women with spontaneous preterm labor. Differential expression profiles of five long non-coding RNAs were identified from loci that overlap with four sarcomeric genes. Longitudinally, the long non-coding RNA of gene TPM3 that encodes the protein tropomysin 3 was found to significantly regulate the mRNA of TPM3 in the placenta, compared to maternal blood. The majority of genome methylation profiles related to premature uterine contraction were also identified in the CpG promoters of sarcomeric genes/loci. Differential expression profiles of mRNAs associated with premature uterine contraction showed 22 genes associated with sarcomeres and three with desmosomes. The results demonstrated that premature uterine contraction was associated mainly with pathogenic variants of the TTN gene and with transcriptomic variations of sarcomeric premature uterine contraction genes. This association is likely regulated by epigenetic factors, including methylation and long non-coding RNAs.

Transcriptomics-determined chemokine-cytokine pathway presents a common pathogenic mechanism in pregnancy loss and spontaneous preterm birth

PROBLEM

Various etiological factors, such as infection and inflammation, may induce the adverse outcomes of pregnancy of miscarriage, stillbirth, or preterm birth. The pathogenic mechanisms associated with these adverse pregnancies are yet unclear. We hypothesized that a common pathogenic mechanism may underlie variant adverse outcomes of pregnancy, which are induced by genetic-environmental factors. The specific objective of the current study is to uncover the common molecular mechanism(s) by identifying the specific transcripts that are present in variant subtypes of pregnancy loss and preterm birth.

METHOD OF STUDY

Transcriptomic profiling was performed with RNA expression microarray or RNA sequencing of placentas derived from pregnancy loss (which includes spontaneous miscarriage, recurrent miscarriage, and stillbirth) and spontaneous preterm birth, followed by bioinformatic analysis of multi-omic integration to identify pathogenic molecules and pathways involved in pathological pregnancies.

RESULTS

The enrichment of common differentially expressed genes between full-term birth and preterm birth and pregnancy loss of miscarriage and stillbirth revealed different pathophysiological pathway(s), including cytokine signaling dysregulated in spontaneous preterm birth, defense response, graft-versus-host disease, antigen processing and presentation, and T help cell differentiation in spontaneous miscarriage. Thirty-three genes shared between spontaneous preterm birth and spontaneous miscarriage were engaged in pathways of interferon gamma-mediated signaling and of antigen processing and presentation. For spontaneous miscarriage, immune response was enriched in the fetal tissue of chorionic villi and in the maternal facet of the placental sac. The transcript of nerve growth factor receptor was identified as the common molecule that is differentially expressed in all adverse pregnancies: spontaneous preterm birth, stillbirth, spontaneous miscarriage, and recurrent miscarriage. Superoxide dismutase 2 was up-regulated in all adverse outcomes of pregnancy except for recurrent miscarriage. Cytokine-cytokine receptor interaction was the common pathway in spontaneous preterm birth and spontaneous miscarriage. Defense response was enriched in the fetal tissue of miscarriage and in the maternal tissue in spontaneous miscarriage.

CONCLUSIONS

Our results indicated that the chemokine-cytokine pathway may play important roles in and function as a common pathogenic mechanism associated with, the different adverse outcomes of pregnancy, which demonstrated that differentially expressed transcripts could result from a common pathogenic mechanism associated with pregnancy loss and spontaneous preterm birth, although individual pregnancy outcomes may differ from each other phenotypically.

EBF1-Correlated Long Non-coding RNA Transcript Levels in 3rd Trimester Maternal Blood and Risk of Spontaneous Preterm Birth

Biomarkers associated with spontaneous preterm birth (sPTB) before labor onset could aid in prediction, triage, and stratification for testing interventions. In this study we examined maternal blood EBF1-correlated long non-coding RNAs (lncRNAs) in relation to sPTB. We retrieved all lncRNA transcripts from a public gene expression dataset (GSE59491) derived from maternal blood in trimesters 2 and 3 from a Canadian cohort with a matched set of sPTB (n = 51) and term births (n = 106). LncRNA transcripts differentially expressed (limma moderated t-tests) in sPTB vs. term were tested for correlations (Pearson) with EBF1 mRNA levels in the same blood samples. Using logistic regression, EBF1-correlated lncRNAs were divided into tertiles and assessed in relation to odds of sPTB. Two lncRNA transcripts in the 3rd trimester maternal blood were differentially expressed between sPTB and term births (all p < 0.001 and FDR < 0.250) and positively and negatively correlated with EBF1 mRNA levels. They were as follows: (1) LINC00094 r = 0.196 (95% CI: 0.039 to 0.344), p = 0.015, and BH adjusted p = 0.022 and (2) LINC00870 r = - 0.303 (95% CI: - 0.441 to - 0.152), p < 0.001, and BH adjusted p < 0.001. As compared with term births, sPTBs were more likely to be in the highest tertile of LINC00870 (odds ratio (OR) = 4.08 (95% CI 1.60, 10.40), p = 0.003) and the lowest tertile of LINC00094 (OR = 5.16 (95% CI 1.96, 13.61), p < 0.001). Two sPTB-associated EBF1-correlated lncRNAs (LINC00870 and LINC00094) had multiple potential enhancers containing EBF1 binding site(s). Our current findings, along with previous reports linking EBF1 and sPTB, motivate additional research on the EBF1 gene-related gene expression and regulation in relation to sPTB within other cohorts and within laboratory-based models.

Proteomic Study of Fetal Membrane: Inflammation-Triggered Proteolysis of Extracellular Matrix May Present a Pathogenic Pathway for Spontaneous Preterm Birth

INTRODUCTION

Spontaneous preterm birth (sPTB), which predominantly presents as spontaneous preterm labor (sPTL) or prelabor premature rupture of membranes (PPROM), is a syndrome that accounts for 5-10% of live births annually. The long-term morbidity in surviving preterm infants is significantly higher than that in full-term neonates. The causes of sPTB are complex and not fully understood. Human placenta, the maternal and fetal interface, is an environmental core of fetal intrauterine life, mediates fetal oxygen exchange, nutrient uptake, and waste elimination and functions as an immune-defense organ. In this study, the molecular signature of preterm birth placenta was assessed and compared to full-term placenta by proteomic profiling.

MATERIALS AND METHODS

Four groups of fetal membranes (the amniochorionic membranes), with five cases in each group in the discovery study and 30 cases in each group for validation, were included: groups A: sPTL; B: PPROM; C: full-term birth (FTB); and D: full-term premature rupture of membrane (PROM). Fetal membranes were dissected and used for proteome quantification study. Maxquant and Perseus were used for protein quantitation and statistical analysis. Both fetal membranes and placental villi samples were used to validate proteomic discovery.

RESULTS

Proteomics analysis of fetal membranes identified 2,800 proteins across four groups. Sixty-two proteins show statistical differences between the preterm and full-term groups. Among these differentially expressed proteins are (1) proteins involved in inflammation (HPGD), T cell activation (PTPRC), macrophage activation (CAPG, CD14, and CD163), (2) cell adhesion (ICAM and ITGAM), (3) proteolysis (CTSG, ELANE, and MMP9), (4) antioxidant (MPO), (5) extracellular matrix (ECM) proteins (APMAP, COL4A1, LAMA2, LMNB1, LMNB2, FBLN2, and CSRP1) and (6) metabolism of glycolysis (PKM and ADPGK), fatty acid synthesis (ACOX1 and ACSL3), and energy biosynthesis (ATP6AP1 and CYBB).

CONCLUSION

Our molecular signature study of preterm fetal membranes revealed inflammation as a major event, which is inconsistent with previous findings. Proteolysis may play an important role in fetal membrane rupture. Extracellular matrix s have been altered in preterm fetal membranes due to proteolysis. Metabolism was also altered in preterm fetal membranes. The molecular changes in the fetal membranes provided a significant molecular signature for PPROM in preterm syndrome.

11β-HSD1 in Human Fetal Membranes as a Potential Therapeutic Target for Preterm Birth

Human parturition is a complex process involving interactions between the myometrium and signals derived from the placenta, fetal membranes, and fetus. Signals originating from fetal membranes are crucial components that trigger parturition, which is clearly illustrated by the labor-initiating consequence of membrane rupture. It has been recognized for a long time that among fetal tissues in late gestation the fetal membranes possess the highest capacity for cortisol regeneration by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). However, the exact role of this unique feature remains a mystery. Accumulating evidence indicates that this extra-adrenal source of cortisol may serve as an upstream signal for critical events in human parturition, including enhanced prostaglandin and estrogen synthesis as well as extracellular matrix remodeling. This may explain why such high capacity for cortisol regeneration develops in human fetal membranes at late gestation. Therefore, inhibition of 11β-HSD1 may provide a potential therapeutic target for prevention of preterm birth. This review summarizes the current understanding of the functional role of cortisol regeneration by 11β-HSD1 in human fetal membranes.

Proteasome-mediated degradation of collagen III by cortisol in amnion fibroblasts

Rupture of fetal membranes (ROM) can initiate parturition at both term and preterm. Collagen III in the compact layer of the amnion contributes to the tensile strength of fetal membranes. However, the upstream signals triggering collagen III degradation remain mostly elusive. In this study, we investigated the role of cortisol regenerated by 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) in collagen III degradation in human amnion fibroblasts with an aim to seek novel targets for the prevention of preterm premature ROM (pPROM)-elicited preterm birth. Human amnion tissue and cultured amnion tissue explants and amnion fibroblasts were used to study the regulation of collagen III, which is composed of three identical 3α 1 chains (COL3A1), by cortisol. Cortisol decreased COL3A1 protein but not mRNA abundance in a concentration-dependent manner. Cortisone also decreased COL3A1 protein, which was blocked by 11β-HSD1 inhibition. The reduction in COL3A1 protein by cortisol was not affected by a transcription inhibitor but was further enhanced by a translation inhibitor. Autophagic pathway inhibitor chloroquine or siRNA-mediated knock-down of ATG7, an essential protein for autophagy, failed to block cortisol-induced reduction in COL3A1 protein abundance, whereas proteasome pathway inhibitors MG132 and bortezomib significantly attenuated cortisol-induced reduction in COL3A1 protein abundance. Moreover, cortisol increased COL3A1 ubiquitination and the reduction of COL3A1 protein by cortisol was blocked by PYR-41, a ubiquitin-activating enzyme inhibitor. Conclusively, cortisol regenerated in amnion fibroblasts may be associated with ROM at parturition by reducing collagen III protein abundance through a ubiquitin-proteasome pathway.