Pregnancy-specific transcriptional changes upon endotoxin exposure in mice

Integration of transcriptomics and metabolomics reveals the responses of the maternal circulation and maternal-fetal interface to LPS-induced preterm birth in mice

Background

Term birth (TB) and preterm birth (PTB) are characterized by uterine contractions, rupture of the chorioamniotic membrane, decidual activation, and other physiological and pathological changes. In this study, we hypothesize that inflammation can cause changes in mRNA expression and metabolic stability in the placenta, decidua, chorioamniotic membrane, uterus and peripheral blood, ultimately leading to PTB.

Methods

To comprehensively assess the effects of inflammation on mRNA expression and metabolite production in different tissues of pregnancy, we used a mouse PTB model by intraperitoneally injecting lipopolysaccharide (LPS) and integrated transcriptomics and metabolomics studies.

Results

Our analysis identified 152 common differentially expressed genes (DEGs) and 8 common differentially expressed metabolites (DEMs) in the placenta, decidua, chorioamniotic membrane, uterus, and peripheral blood, or placenta and uterus after LPS injection, respectively. Our bioinformatics analysis revealed significant enrichment of the NOD-like receptor signaling pathway (mmu04621), TNF signaling pathway (mmu04668), IL-17 signaling pathway (mmu04657), and NF-kappa B signaling pathway in the transcriptomics of different tissues, and Hormone synthesis, Lysosome, NOD-like receptor signaling pathway, and Protein digest and absorption pathway in metabolomics. Moreover, we found that several upstream regulators and master regulators, including STAT1, STAT3, and NFKB1, were altered after exposure to inflammation in the different tissues. Interaction network analysis of transcriptomics and metabolomics DEGs and DEMs also revealed functional changes in mice intraperitoneally injected with LPS.

Conclusions

Overall, our study identified significant and biologically relevant alterations in the placenta, decidua, chorioamniotic membrane, uterus, peripheral blood transcriptome and the placenta and uterus metabolome in mice exposed to LPS. Thus, a comprehensive analysis of different pregnancy tissues in mice intraperitoneally injected with LPS by combining transcriptomics and metabolomics may help to systematically understand the local and systemic changes associated with PTB caused by inflammation.

A single-cell atlas of murine reproductive tissues during preterm labor

Preterm birth, the leading cause of perinatal morbidity and mortality worldwide, frequently results from the syndrome of preterm labor. The best-established causal link to preterm labor is intra-amniotic infection, which involves premature activation of the parturition cascade in the reproductive tissues. Herein, we utilize single-cell RNA sequencing (scRNA-seq) to generate a single-cell atlas of the murine uterus, decidua, and cervix in a model of infection-induced preterm labor. We show that preterm labor affects the transcriptomic profiles of specific immune and non-immune cell subsets. Shared and tissue-specific gene expression signatures are identified among affected cells. Determination of intercellular communications implicates specific cell types in preterm labor-associated signaling pathways across tissues. In silico comparison of murine and human uterine cell-cell interactions reveals conserved signaling pathways implicated in labor. Thus, our scRNA-seq data provide insights into the preterm labor-driven cellular landscape and communications in reproductive tissues.

Toward a new taxonomy of obstetrical disease: improved performance of maternal blood biomarkers for the great obstetrical syndromes when classified according to placental pathology

BACKGROUND

The major challenge for obstetrics is the prediction and prevention of the great obstetrical syndromes. We propose that defining obstetrical diseases by the combination of clinical presentation and disease mechanisms as inferred by placental pathology will aid in the discovery of biomarkers and add specificity to those already known.

OBJECTIVE

To describe the longitudinal profile of placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), and the PlGF/sFlt-1 ratio throughout gestation, and to determine whether the association between abnormal biomarker profiles and obstetrical syndromes is strengthened by information derived from placental examination, eg, the presence or absence of placental lesions of maternal vascular malperfusion.

STUDY DESIGN

This retrospective case cohort study was based on a parent cohort of 4006 pregnant women enrolled prospectively. The case cohort of 1499 pregnant women included 1000 randomly selected patients from the parent cohort and all additional patients with obstetrical syndromes from the parent cohort. Pregnant women were classified into six groups: 1) term delivery without pregnancy complications (n=540; control); 2) preterm labor and delivery (n=203); 3) preterm premature rupture of the membranes (n=112); 4) preeclampsia (n=230); 5) small-for-gestational-age neonate (n=334); and 6) other pregnancy complications (n=182). Maternal plasma concentrations of PlGF and sFlt-1 were determined by enzyme-linked immunosorbent assays in 7560 longitudinal samples. Placental pathologists, masked to clinical outcomes, diagnosed the presence or absence of placental lesions of maternal vascular malperfusion. Comparisons between mean biomarker concentrations in cases and controls were performed by utilizing longitudinal generalized additive models. Comparisons were made between controls and each obstetrical syndrome with and without subclassifying cases according to the presence or absence of placental lesions of maternal vascular malperfusion.

RESULTS

1) When obstetrical syndromes are classified based on the presence or absence of placental lesions of maternal vascular malperfusion, significant differences in the mean plasma concentrations of PlGF, sFlt-1, and the PlGF/sFlt-1 ratio between cases and controls emerge earlier in gestation; 2) the strength of association between an abnormal PlGF/sFlt-1 ratio and the occurrence of obstetrical syndromes increases when placental lesions of maternal vascular malperfusion are present (adjusted odds ratio [aOR], 13.6 vs 6.7 for preeclampsia; aOR, 8.1 vs 4.4 for small-for-gestational-age neonates; aOR, 5.5 vs 2.1 for preterm premature rupture of the membranes; and aOR, 3.3 vs 2.1 for preterm labor (all P<0.05); and 3) the PlGF/sFlt-1 ratio at 28 to 32 weeks of gestation is abnormal in patients who subsequently delivered due to preterm labor with intact membranes and in those with preterm premature rupture of the membranes if both groups have placental lesions of maternal vascular malperfusion. Such association is not significant in patients with these obstetrical syndromes who do not have placental lesions.

CONCLUSION

Classification of obstetrical syndromes according to the presence or absence of placental lesions of maternal vascular malperfusion allows biomarkers to be informative earlier in gestation and enhances the strength of association between biomarkers and clinical outcomes. We propose that a new taxonomy of obstetrical disorders informed by placental pathology will facilitate the discovery and implementation of biomarkers as well as the prediction and prevention of such disorders.

Pregnancy tailors endotoxin-induced monocyte and neutrophil responses in the maternal circulation

Objective

To comprehensively characterize monocyte and neutrophil responses to E. coli and its product [lipopolysaccharide (LPS) or endotoxin] in vitro during pregnancy.

Material or subjects

Peripheral blood was collected from pregnant women during the third trimester (n = 20) and from non-pregnant women (n = 20).

Methods

The number, phagocytic activity, and reactive oxygen species (ROS) production of peripheral monocytes and neutrophils were investigated using flow cytometry. The phenotypes of peripheral monocytes and neutrophils after acute or chronic LPS stimulation were also determined using flow cytometry. Cytokine profiles were quantified for LPS-stimulated peripheral blood mononuclear cells (PBMCs) and a whole blood TruCulture^® system using a multiplex immunoassay.

Results

Increased number, phagocytic activity, and ROS production capacity of monocytes and neutrophils were found in pregnant compared to non-pregnant women. Additionally, specific subsets of pro-inflammatory monocytes (IL-6⁺CD14⁺ or MIP-1α⁺CD14⁺ cells) and neutrophils (IL-1β⁺CD15⁺ or MIP-1β⁺CD15⁺ cells) were increased in pregnant women in response to acute LPS stimulation. Moreover, distinct subsets of intermediate-activated monocytes expressing CD142, IL-6, and IL-1RA were increased in pregnant women upon chronic LPS stimulation. Last, pregnant women displayed a different cytokine profile than non-pregnant women in LPS-stimulated PBMCs and in whole blood.

Conclusions

Pregnancy tailors the immune responses of circulating monocytes and neutrophils to endotoxin, a Gram-negative bacterial product.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00011-022-01569-z.

Distinct Cellular Immune Responses to SARS-CoV-2 in Pregnant Women

Pregnant women are at increased risk of adverse outcomes, including preeclampsia and preterm birth, that may result from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Pregnancy imprints specific maternal immune responses that can modulate host susceptibility to microbial infection; therefore, recent studies have focused on the humoral response against SARS-CoV-2 in pregnant women. However, the pregnancy-specific cellular immune responses triggered by SARS-CoV-2 infection are poorly understood. In this study, we undertook an extensive in vitro investigation to determine the cellular immune responses to SARS-CoV-2 particles and proteins/peptides in pregnant women. First, we show that SARS-CoV-2 particles do not alter the pregnancy-specific oxidative burst of neutrophils and monocytes. Yet, SARS-CoV-2 particles/proteins shift monocyte activation from the classical to intermediate states in pregnant, but not in nonpregnant, women. Furthermore, SARS-CoV-2 proteins, but not particles or peptide pools, mildly enhance T cell activation during pregnancy. As expected, B cell phenotypes are heavily modulated by SARS-CoV-2 particles in all women; yet, pregnancy itself further modified such responses in these adaptive immune cells. Lastly, we report that pregnancy itself governs cytokine responses in the maternal circulation, of which IFN-β and IL-8 were diminished upon SARS-CoV-2 challenge. Collectively, these findings highlight the differential in vitro responses to SARS-CoV-2 in pregnant and nonpregnant women and shed light on the immune mechanisms implicated in coronavirus disease 2019 during pregnancy.