De novo Synthesis of SAA1 in the Placenta Participates in Parturition

Differential gene expression in two consecutive pregnancies between same sex siblings and implications on maternal constraint

The objective of this study was to investigate how placental gene expression differs in two consecutive pregnancies in same sex siblings, and its possible association with the "maternal constraint" hypothesis. Material was gathered from the BASIC study (Biological, Affect, Stress, Imaging, and Cognition in Pregnancy and the Puerperium), a population based prospective study that was started in 2009 in Uppsala. Over 900 specimens of placenta biopsies were collected and out of these 10 women gave birth twice, to the same sex child, and were included in this study. The total RNA was isolated and prepared from frozen villous tissue from the placenta and further analyzed by use of Ion AmpliSeq Human Transcriptome Gene Expression kit. A total of 234 genes differed significantly between the first and second pregnancy placentas, when adjusting for delivery mode, maternal BMI and gestational age. Of special interest was the down-regulated group of genes in the second pregnancy. Exemplified by Pentraxin 3, SRY-Box Transcription Factor 9, and Serum Amyloid A1, which all were associated with biological processes involved in the immune system and inflammation. Further, protein-protein interaction analysis visualized them as hub genes interacting with several of the other differentially expressed genes. How these altered gene expressions affect maternal constraint during pregnancy needs further validation in lager study cohorts and also future validation in functional assays.

Amnion-derived serum amyloid A1 participates in sterile inflammation of fetal membranes at parturition

OBJECTIVES

Sterile inflammation of fetal membranes is an indispensable event of normal parturition. However, triggers of sterile inflammation are not fully resolved. Serum amyloid A1 (SAA1) is an acute phase protein produced primarily by the liver. Fetal membranes can also synthesize SAA1 but its functions are not well defined. Given the role of SAA1 in the acute phase response to inflammation, we postulated that SAA1 synthesized in the fetal membranes may be a trigger of local inflammation at parturition.

METHODS

The changes of SAA1 abundance in parturition were studied in the amnion of human fetal membranes. The role of SAA1 in chemokine expression and leukocyte chemotaxis was examined in cultured human amnion tissue explants as well as primary human amnion fibroblasts. The effects of SAA1 on monocytes, macrophages and dendritic cells were investigated in cells derived from a human leukemia monocytic cell line (THP-1).

RESULTS

SAA1 synthesis increased significantly in human amnion at parturition. SAA1 evoked multiple chemotaxis pathways in human amnion fibroblasts along with upregulation of a series of chemokines via both toll-like receptor 4 (TLR4) and formyl peptide receptor 2 (FPR2). Moreover, SAA1-conditioned medium of cultured amnion fibroblasts was capable of chemoattracting virtually all types of mononuclear leukocytes, particularly monocytes and dendritic cells, which reconciled with the chemotactic activity of conditioned medium of cultured amnion tissue explants collected from spontaneous labor. Furthermore, SAA1 could induce the expression of genes associated with inflammation and extracellular matrix remodeling in monocytes, macrophages and dendritic cells derived from THP-1.

CONCLUSIONS

SAA1 is a trigger of sterile inflammation of the fetal membranes at parturition.

Serum amyloid A1 and pregnancy zone protein in pregnancy complications and correlation with markers of placental dysfunction

BACKGROUND

Hypertensive disorders of pregnancy (preeclampsia, gestational hypertension, and chronic hypertension), diabetes mellitus, and placental dysfunction confer an increased risk of long-term maternal cardiovascular disease. Preeclampsia is also associated with acute atherosis that involves lesions of uteroplacental spiral arteries, resembling early stages of atherosclerosis. Serum amyloid A1 is involved in hypercoagulability and atherosclerosis and may aggregate into amyloid-aggregations of misfolded proteins. Pregnancy zone protein may inhibit amyloid aggregation. Amyloid is involved in Alzheimer's disease and cardiovascular disease; it has been identified in preeclampsia, but its role in preeclampsia pathophysiology is unclear.

OBJECTIVE

We hypothesized that serum amyloid A1 would be increased and pregnancy zone protein decreased in hypertensive disorders of pregnancy and diabetic pregnancies and that serum amyloid A1 and pregnancy zone protein would correlate with placental dysfunction markers (fetal growth restriction and dysregulated angiogenic biomarkers) and acute atherosis.

STUDY DESIGN

Serum amyloid A1 is measurable in both the serum and plasma. In our study, plasma from 549 pregnancies (normotensive, euglycemic controls: 258; early-onset preeclampsia: 71; late-onset preeclampsia: 98; gestational hypertension: 30; chronic hypertension: 9; diabetes mellitus: 83) was assayed for serum amyloid A1 and pregnancy zone protein. The serum levels of angiogenic biomarkers soluble fms-like tyrosine kinase-1 and placental growth factor were available for 547 pregnancies, and the results of acute atherosis evaluation were available for 313 pregnancies. The clinical characteristics and circulating biomarkers were compared between the pregnancy groups using the Mann-Whitney U, chi-squared, or Fisher exact test as appropriate. Spearman's rho was calculated for assessing correlations.

RESULTS

In early-onset preeclampsia, serum amyloid A1 was increased compared with controls (17.1 vs 5.1 µg/mL, P<.001), whereas pregnancy zone protein was decreased (590 vs 892 µg/mL, P=.002). Pregnancy zone protein was also decreased in diabetes compared with controls (683 vs 892 µg/mL, P=.01). Serum amyloid A1 was associated with placental dysfunction (fetal growth restriction, elevated soluble fms-like tyrosine kinase-1 to placental growth factor ratio). Pregnancy zone protein correlated negatively with soluble fms-like tyrosine kinase-1 to placental growth factor ratio in all study groups. Acute atherosis was not associated with serum amyloid A1 or pregnancy zone protein.

CONCLUSION

Proteins involved in atherosclerosis, hypercoagulability, and protein misfolding are dysregulated in early-onset preeclampsia and placental dysfunction, which links them and potentially contributes to future maternal cardiovascular disease.

Maternal siRNA silencing of placental SAA2 mitigates preterm birth following intrauterine inflammation

The placental inflammatory processes induced maternally result in preterm birth (PTB). Serum amyloid A (SAA) is a well-known biomarker of inflammation. The objective of this study was to investigate whether murine placental SAA isoforms (SAA1–4) participate in the mechanism of spontaneous PTB and whether maternal regulation of SAA production may serve as a therapeutic approach. During the gestation, all isoforms of SAA were detectable except SAA2. The mouse model of intrauterine inflammation was established using LPS infusion to the uterus. Following intrauterine inflammation, placental SAA2 increased significantly. Inhibition of Saa2, using siSaa2, markedly decreased PTB. The increased placental expression of pro-inflammatory cytokines Il1β, Il6, and Tnfα were downregulated by siSaa2 treatment. Maternal inhibition of Saa2 did not change the expression of Saa1–4 in the fetal brain. Explant inflammatory culture of placentas with siSaa2 showed similar results to our in vivo experiments. This study demonstrates the highly expressed placental SAA2 as a novel therapeutic target, and maternal administration of siRNA as a promising approach to alleviate PTB.

Serum amyloid A, a host-derived DAMP in pregnancy?

Serum amyloid A (SAA) is one of the acute phase proteins released primarily from the liver in response to infection, inflammation and trauma. Emerging evidence indicates that SAA may function as a host-derived damage-associated molecular pattern (DAMP) protein to sense danger signals in pregnancy. The plasma SAA levels in maternal circulation are significantly increased in normal parturition, particularly in postpartum, as well as in gestational disorders such as premature preterm rupture of membranes, pre-eclampsia, gestational diabetes, and recurrent spontaneous abortion. It is likely that SAA acts as a non-specific DAMP molecule in response to inflammation and trauma experienced under these conditions. Notably, SAA can also be synthesized locally in virtually all gestational tissues. Within these gestational tissues, under the induction by bacterial products, pro-inflammatory cytokines and stress hormone glucocorticoids, SAA may exert tissue-specific effects as a toll-like receptor 4 (TLR4)-sensed DAMP molecule. SAA may promote parturition through stimulation of inflammatory reactions via induction of pro-inflammatory cytokines, chemokines, adhesion molecules and prostaglandins in the uterus, fetal membranes and placenta. In the fetal membranes, SAA may also facilitate membrane rupture through induction of matrix metalloproteases (MMPs)- and autophagy-mediated collagen breakdown and attenuation of lysyl oxidase-mediated collagen cross-linking. SAA synthesized in extravillous trophoblasts may promote their invasiveness into the endometrium in placentation. Here, we summarized the current understanding of SAA in pregnancy with an aim to stimulate in-depth investigation of SAA in pregnancy, which may help better understand how inflammation is initiated in gestational tissues in both normal and abnormal pregnancies.

Role of EZH2-mediated H3K27me3 in placental ADAM12-S expression: implications for fetoplacental growth

BACKGROUND

Enhancer of zeste homolog 2 (EZH2)-mediated histone 3 lysine 27 trimethylation (H3K27me3) is a transcription silencing mark, which is indispensable for cell lineage specification at the early blastocyst stage. This epigenetic repression is maintained in placental cytotrophoblasts but is lifted when cytotrophoblasts differentiate into syncytiotrophoblasts. However, the physiological impact of this lift remains elusive. Here, we investigated whether lifting EZH2-mediated H3K27me3 during syncytialization upregulates the expression of a short secretory isoform of a disintegrin and metalloprotease 12 (ADAM12-S), a well-recognized placenta-derived protease that cleaves insulin-like growth factor binding protein 3 to increase insulin-like growth factor (IGF) bioavailability for the stimulation of fetoplacental growth. The transcription factor and the upstream signal involved were also explored.

METHODS

Human placenta tissue and cultured primary human placental cytotrophoblasts were utilized to investigate the role of EZH2-mediated H3K27me3 in ADAM12-S expression and the associated transcription factor and upstream signal during syncytialization. A mouse model was used to examine whether inhibition of EZH2-mediated H3K27me3 regulates placental ADAM12-S expression and fetoplacental growth.

RESULTS

EZH2 and ADAM12 are distributed primarily in villous cytotrophoblasts and syncytiotrophoblasts, respectively. Increased ADAM12-S expression, decreased EZH2 expression, and decreased EZH2/H3K27me3 enrichment at the ADAM12 promoter were observed during syncytialization. Knock-down of EZH2 further increased ADAM12-S expression in trophoblasts. Syncytialization was also accompanied by increased STAT5B expression and phosphorylation as well as its enrichment at the ADAM12 promoter. Knock-down of STAT5B attenuated ADAM12-S expression during syncytialization. Epidermal growth factor (EGF) was capable of inducing ADAM12-S expression via stimulation of STAT5B expression and phosphorylation during syncytialization. Mouse studies revealed that administration of an EZH2 inhibitor significantly increased ADAM12-S levels in maternal blood and fetoplacental weights along with decreased H3K27me3 abundance and increased ADAM12-S expression in the placenta.

CONCLUSIONS

Lifting EZH2-mediated H3K27me3 increases ADAM12-S expression during syncytialization with the participation of EGF-activated STAT5B, which may lead to elevation of ADAM12-S level in maternal blood resulting in increased IGF bioavailability for the stimulation of fetoplacental growth in pregnancy. Our studies suggest that the role of EZH2-mediated H3K27me3 may switch from cell lineage specification at the early blastocyst stage to regulation of fetoplacental growth in later gestation.

A Novel Five-Gene Signature Related to Clinical Outcome and Immune Microenvironment in Breast Cancer

Breast cancer (BC) is the most frequent cancer in women and the main cause of cancer-related deaths in the globe, according to the World Health Organization. The need for biomarkers that can help predict survival or guide treatment decisions in BC patients is critical in order to provide each patient with an individualized treatment plan due to the wide range of prognoses and therapeutic responses. A reliable prognostic model is essential for determining the best course of treatment for patients. Patients’ clinical and pathological data, as well as their mRNA expression levels at level 3, were gleaned from the TCGA databases. Differentially expressed genes (DEGs) between BC and non-tumor specimens were identified. Tumor immunity analyses have been utilized in order to decipher molecular pathways and their relationship to the immune system. The expressions of KIF4A in BC cells were determined by RT-PCR. To evaluate the involvement of KIF4A in BC cell proliferation, CCK-8 tests were used. In this study, utilizing FC > 4 and p < 0.05, we identified 140 upregulated genes and 513 down-regulated genes. A five-gene signature comprising SFRP1, SAA1, RBP4, KIF4A and COL11A1 was developed for the prediction of overall survivals of BC. Overall survival was distinctly worse for patients in the high-risk group than those in the low-risk group. Cancerous and aggressiveness-related pathways and decreased B cell, T cell CD4⁺, T cell CD8⁺, Neutrophil and Myeloid dendritic cells levels were seen in the high-risk group. In addition, we found that KIF4A was highly expressed in BC and its silence resulted in the suppression of the proliferation of BC cells. Taken together, as a possible prognostic factor for BC, the five-gene profile created and verified in this investigation could guide the immunotherapy selection.

The Bradykinin System Contributes to the Regulation of Prostaglandin-Endoperoxide Synthase 2 Expression in Human Amnion Fibroblasts: Implications for Term and Preterm Birth

BACKGROUND

Bradykinin (BK) and its biologically active metabolite des-Arg9 bradykinin (DABK) play a pivotal role in inflammation. Since chorioamnionitis is the leading cause of preterm birth and prostaglandin E2 (PGE2) derived from the amnion is key to labor initiation, we investigated if bradykinin peptides are part of the regulatory network of PGE2 synthesis in human amnion at parturition.

METHODS

Human amnion tissue was obtained from term and preterm birth for the study of the changes of the bradykinin system at parturition. Cultured primary human amnion fibroblasts, the major source of PGE2, were used to study the effects of bradykinin peptides on PTGS2 expression and PGE2 production as well as the effects of infection mediators on bradykinin receptors.

RESULTS

Bradykinin peptides and their receptors BDKRB1 and BDKRB2 were present in human amnion, and their abundance increased in term and preterm labor. However, transcripts of the genes encoding the bradykinin precursor and its proteolytic cleavage enzymes were hardly detectable in human amnion despite the increased abundance of bradykinin peptides in term and preterm labor, suggesting that there is an alternative source of bradykinin peptides for human amnion and their actions are enhanced in human amnion at parturition. In-vitro studies in cultured human amnion fibroblasts showed that both BK and DABK increased the expression of prostaglandin-endoperoxide synthase 2 (PTGS2), the rate-limiting enzyme in prostaglandin synthesis, and subsequent PGE2 production. These effects of BK and DABK were mediated through BDKRB2 and BDKRB1 receptors, respectively, with subsequent activation of the p38 and ERK1/2 pathways. Moreover, lipopolysaccharide (LPS) and serum amyloid A1 (SAA1), the important mediators of infectious inflammation, induced the expression of both BDKRB1 and BDKRB2 through toll-like receptor 4 (TLR4). Induction of BDKRB1 and BDKRB2 expression by LPS and SAA1 enhanced BK- or DABK-induced PTGS2 expression and PGE2 production in human amnion fibroblasts.

CONCLUSIONS

This study demonstrated for the first time that the human amnion is a target tissue of bradykinin peptides and the bradykinin system may be part of the regulatory network of PTGS2 expression and PGE2 production in human amnion fibroblasts at both term and preterm birth, which may be enhanced by infection.

Assessment of serum amyloid A concentrations and biochemical profiles in lactating jennies and newborn Ragusano donkey foals around parturition and one month after foaling in Sicily

A proper knowledge of biochemical parameters and inflammatory markers like serum amyloid A (SAA) is crucial in the monitoring of the first post‐partum period in equids. Since no information is available on SAA for donkeys at this stage, 50 animals including jennies (n.10) and newborn foals (n.10) within 48 hr from foaling, and jennies (n.10) and foals (n.20) after 30 days from parturition were enrolled in the study to assess routine biochemical profile including SAA. Jennies showed higher alkaline phosphatase and lower bilirubins and cholesterol at 30 days of lactation compared to post‐partum. Neonatal donkey foals showed significant higher concentrations of sodium, alkaline phosphatase, lactic dehydrogenase, blood urea nitrogen, creatinine and albumin within 48 hr of age, whilst higher values of phosphate and triglycerides were observed in older foals of 30 days of age. Significant higher SAA concentrations were recorded during the peripartum period in both jennies (25.95 ± 14.98 μg/ml) and newborn donkey foals (37.44 ± 19.75 μg/ml) compared to SAA values recorded in lactating jennies (2.38 ± 1.78 μg/ml) and in donkey foals (16.04 ± 18.14 μg/ml) at 30 days after parturition. The assessment of SAA in jennies and donkey foals around parturition and one month after foaling represents a valuable tool for the monitoring of health status during this stage when animals have to face with new challenges like the peak of lactation and extrauterine life adaptation respectively.

Identification of Potential Risk Genes and the Immune Landscape of Idiopathic Pulmonary Arterial Hypertension via Microarray Gene Expression Dataset Reanalysis

Gene dysfunction and immune cell infiltration play an essential role in the pathogenesis of idiopathic pulmonary arterial hypertension (IPAH). We aimed to investigate the immune landscape and novel differentially expressed genes (DEGs) of IPAH. In addition, potential druggable molecular targets for IPAH were also explored. In this study, the GSE117261 dataset was reanalyzed to explore the immune landscape and hub DEGs of IPAH. Lasso Cox regression analysis and receiver operating characteristic curve analysis were performed to detect the predictive value of IPAH. Additionally, the underlying drug targets for IPAH treatment were determined by drug-gene analysis. IPAH was significantly associated with the transforming growth factor-β (TGF-β) signaling pathway and Wnt signaling pathway as well as energetic metabolism dysfunction. We identified 31 upregulated and 39 downregulated DEGs in IPAH patients. Six hub genes, namely, SAA1, CCL5, CXCR1, CXCR2, CCR1, and ADORA3, were related to IPAH pathogenesis regardless of sex differences. Prediction model analysis showed that the area under the curve values of the hub DEGs except CXCR2 were all above 0.9 for distinguishing IPAH patients. In addition, the relative proportions of 5 subtypes of immune cells, namely, CD₈ ⁺ T cells, CD₄ ⁺ memory resting T cells, γ delta T cells, M1 macrophages, and resting mast cells, were significantly upregulated in the IPAH samples, while 6 subtypes of immune cells, namely, CD₄ ⁺ naive T cells, resting NK cells, monocytes, M0 macrophages, activated mast cells, and neutrophils, were downregulated. Additionally, a total of 17 intersecting drugs targeting 5 genes, CCL5, CXCR1, CXCR2, CCR1, and ADORA3, were generated as potential druggable molecular targets for IPAH. Our study revealed the underlying correlations between genes and immune cells in IPAH and demonstrated for the first time that SAA1, CCL5, CXCR1, CCR1, and ADORA3 may be novel genetic targets for IPAH.