The pregnancy microbiome and preterm birth

Preterm birth is a global health concern and continues to contribute to substantial neonatal morbidity and mortality despite advances in obstetric and neonatal care. The underlying aetiology is multi-factorial and remains incompletely understood. In this review, the complex interplay between the vaginal microbiome in pregnancy and its association with preterm birth is discussed in depth. Advances in the study of bacteriology and an improved understanding of the human microbiome have seen an improved awareness of the vaginal microbiota in both health and in disease

NALP1 in vitiligo-associated multiple autoimmune disease.

BACKGROUND: Autoimmune and autoinflammatory diseases involve interactions between genetic risk factors and environmental triggers. We searched for a gene on chromosome 17p13 that contributes to a group of epidemiologically associated autoimmune and autoinflammatory diseases. The group includes various combinations of generalized vitiligo, autoimmune thyroid disease, latent autoimmune diabetes in adults, rheumatoid arthritis, psoriasis, pernicious anemia, systemic lupus erythematosus, and Addison's disease. METHODS: We tested 177 single-nucleotide polymorphisms (SNPs) spanning the 17p13 linkage peak for association with disease and identified a strong candidate gene. We then sequenced DNA in and around the gene to identify additional SNPs. We carried out a second round of tests of association using some of these additional SNPs, thus elucidating the association with disease in the gene and its extended promoter region in fine detail. RESULTS: Association analyses resulted in our identifying as a candidate gene NALP1, which encodes NACHT leucine-rich-repeat protein 1, a regulator of the innate immune system. Fine-scale association mapping with the use of DNA from affected families and additional SNPs in and around NALP1 showed an association of specific variants with vitiligo alone, with an extended autoimmune and autoinflammatory disease phenotype, or with both. Conditional logistic-regression analysis of NALP1 SNPs indicated that at least two variants contribute independently to the risk of disease. CONCLUSIONS: DNA sequence variants in the NALP1 region are associated with the risk of several epidemiologically associated autoimmune and autoinflammatory diseases, implicating the innate immune system in the pathogenesis of these disorders

The local and systemic immune response to intrauterine LPS in the prepartum mouse

Inflammation plays a key role in human term and preterm labor (PTL). Intrauterine LPS has been widely used to model inflammation-induced complications of pregnancy, including PTL. It has been shown to induce an intense myometrial inflammatory cell infiltration, but the role of LPS-induced inflammatory cell activation in labor onset and fetal demise is unclear. We investigated this using a mouse model of PTL, where an intrauterine injection of 10 μg of LPS (serotype 0111:B4) was given at E16 of CD1 mouse pregnancy. This dose induced PTL at an average of 12.7 h postinjection in association with 85% fetal demise. Flow cytometry showed that LPS induced a dramatic systemic inflammatory response provoking a rapid and marked leucocyte infiltration into the maternal lung and liver in association with increased cytokine levels. Although there was acute placental inflammatory gene expression, there was no corresponding increase in fetal brain inflammatory gene expression until after fetal demise. There was marked myometrial activation of NFκB and MAPK/AP-1 systems in association with increased chemokine and cytokine levels, both of which peaked with the onset of parturition. Myometrial macrophage and neutrophil numbers were greater in the LPS-injected mice with labor onset only; prior to labor, myometrial neutrophils and monocytes numbers were greater in PBS-injected mice, but this was not associated with an earlier onset of labor. These data suggest that intrauterine LPS induces parturition directly, independent of myometrial inflammatory cell infiltration, and that fetal demise occurs without fetal inflammation. Intrauterine LPS provokes a marked local and systemic inflammatory response but with limited inflammatory cell infiltration into the myometrium or placenta

Specific Lipopolysaccharide Serotypes Induce Differential Maternal and Neonatal Inflammatory Responses in a Murine Model of Preterm Labor.

Intrauterine inflammation is recognized as a key mediator of both normal and preterm birth but is also associated with neonatal neurological injury. Lipopolysaccharide (LPS) is often used to stimulate inflammatory pathways in animal models of infection/inflammation-induced preterm labor; however, inconsistencies in maternal and neonatal responses to LPS are frequently reported. We hypothesized that LPS serotype-specific responses may account for a portion of these inconsistencies. Four different Escherichia coli LPS serotypes (O111:B4, O55:B5, O127:B8, and O128:B12) were administered to CD1 mice via intrauterine injection at gestational day 16. Although control animals delivered at term 60 ± 15 hours postinjection (p.i.), those administered with O111:B4 delivered 7 ± 2 hours p.i., O55:B5 delivered 10 ± 3 hours p.i., O127:B8 delivered 16 ± 10 hours p.i., and O128:B12 delivered 17 ± 2 hours p.i. (means ± SD). A correlation between the onset of preterm labor and myometrial activation of the inflammatory transcription factor, activator protein 1, but not NF-κB was observed. Specific LPS serotypes induced differential activation of downstream contractile and inflammatory pathways in myometrium and neonatal pup brain. Our findings demonstrate functional disparity in inflammatory pathway activation in response to differing LPS serotypes. Selective use of LPS serotypes may represent a useful tool for targeting specific inflammatory response mechanisms in these models

Modeling hormonal and inflammatory contributions to preterm and term labor using uterine temporal transcriptomics

BACKGROUND: Preterm birth is now recognized as the primary cause of infant mortality worldwide. Interplay between hormonal and inflammatory signaling in the uterus modulates the onset of contractions; however, the relative contribution of each remains unclear. In this study we aimed to characterize temporal transcriptome changes in the uterus preceding term labor and preterm labor (PTL) induced by progesterone withdrawal or inflammation in the mouse and compare these findings with human data. METHODS: Myometrium was collected at multiple time points during gestation and labor from three murine models of parturition: (1) term gestation; (2) PTL induced by RU486; and (3) PTL induced by lipopolysaccharide (LPS). RNA was extracted and cDNA libraries were prepared and sequenced using the Illumina HiSeq 2000 system. Resulting RNA-Seq data were analyzed using multivariate modeling approaches as well as pathway and causal network analyses and compared against human myometrial transcriptome data. RESULTS: We identified a core set of temporal myometrial gene changes associated with term labor and PTL in the mouse induced by either inflammation or progesterone withdrawal. Progesterone withdrawal initiated labor without inflammatory gene activation, yet LPS activation of uterine inflammation was sufficient to override the repressive effects of progesterone and induce a laboring phenotype. Comparison of human and mouse uterine transcriptomic datasets revealed that human labor more closely resembles inflammation-induced PTL in the mouse. CONCLUSIONS: Labor in the mouse can be achieved through inflammatory gene activation yet these changes are not a requisite for labor itself. Human labor more closely resembles LPS-induced PTL in the mouse, supporting an essential role for inflammatory mediators in human "functional progesterone withdrawal." This improved understanding of inflammatory and progesterone influence on the uterine transcriptome has important implications for the development of PTL prevention strategies

Specific staining of human chromosomes in Chinese hamster x man hybrid cell lines demonstrates interphase chromosome territories

In spite of Carl Rabl's (1885) and Theodor Boveri's (1909) early hypothesis that chromosomes occupy discrete territories or domains within the interphase nucleus, evidence in favor pf this hypothesis has been limited and indirect so far in higher plants and animals. The alternative possibility that the chromatin fiber of single chromosomes might be extended throughout the major part of even the whole interphase nucleus has been considered for many years. In the latter case, chromosomes would only exist as discrete chromatin bodies during mitosis but not during interphase. Both possibilities are compatible with Boveri's well established paradigm of chromosome individuality. Here we show that an active human X chromosome contained as the only human chromosome in a Chinese hamster x man hybrid cell line can be visualized both in metaphse plates and in interphase nuclei after in situ hybridization with either 3H- or biotin-labeled human genomic DNA. We demonstrate that this chromosome is organized as a distinct chromatin body throughout interphase. In addition, evidence for the territorial organization of human chromosomes is also presented for another hybrid cell line containing several autosomes and the human X chromosome. These findings are discussed in the context of our present knowledge of the organization and topography of interphase chromosomes. General applications of a strategy aimed at specific staining of individual chromosomes in experimental and clinical cytogenetics are briefly considered

The interaction between vaginal microbiota, cervical length and vaginal progesterone treatment for preterm birth risk

Background: Preterm birth is the primary cause of infant death worldwide. A short cervix in the second trimester of pregnancy is a risk factor for preterm birth. In specific patient cohorts, vaginal progesterone reduces this risk. Using 16S rRNA gene sequencing we undertook a prospective study in women at risk of preterm birth (n=161) to assess 1) the relationship between vaginal microbiota and cervical length in the second trimester and preterm birth-risk, and 2) the impact of vaginal progesterone on vaginal bacterial communities in women with a short cervix. Results: Lactobacillus iners dominance at 16 weeks gestation was significantly associated with both a short cervix <25mm (n=15, P<0.05), and preterm birth <34+0 weeks (n=18, 38P<0.01; 69% PPV). In contrast, L. crispatus dominance was highly predictive of term birth (n=127, 98% PPV). Cervical shortening and preterm birth were not associated with vaginal dysbiosis. A longitudinal characterization of vaginal microbiota (<18, 22, 28 and 34 weeks) was then undertaken in women receiving vaginal progesterone (400mg/OD, n=25) versus controls (n=42). Progesterone did not alter vaginal bacterial community structure nor reduce L. iners-associated preterm birth (<34 weeks). Conclusions: L. iners dominance of the vaginal microbiota at 16 weeks gestation is a risk factor for preterm birth, whereas L. crispatus dominance is protective against preterm birth. Vaginal progesterone does not appear to impact the pregnancy vaginal microbiota. Patients and clinicians who may be concerned about ‘infection risk’ associated with use of a vaginal pessary during high-risk pregnancy can be reassured

Use of magnesium sulfate in preterm deliveries for neuroprotection of the neonate

Key content The prevalence of preterm birth is increasing and owing to advances in neonatal care, more infants are surviving. However, in parallel with this, the incidence of cerebral palsy (CP) is also rising. Magnesium sulfate (MgSO4) is currently recommended for use in women who are at risk of giving birth at less than 30–32 weeks of gestation for neuroprotection of their infants. The exact mechanism of action remains unclear. Meta‐analyses report encouraging results that are consistent with a modest but tangible benefit for the use of MgSO4, and suggest a number needed to treat (NNT) to prevent one in 46 cases of CP in infants born preterm before 30 weeks of gestation and one in 63 cases of CP in infants born preterm before 34 weeks of gestation. Learning objectives To gain an understanding of the risk of neurodisability in infants delivered preterm. To become familiar with the main studies assessing the use of MgSO4 for neuroprotection in preterm deliveries. To become aware of the relevant international guidelines. Ethical issues Concerns have been raised regarding the higher number of perinatal deaths reported with the use of MgSO4 in the MagNET study. This was not substantiated in the Cochrane review. Given that MgSO4 is a safe, readily available and inexpensive drug, even if there were only to be modest benefits from its use, the risk–benefit ratio is in favour of its use

Study protocol : the empirical investigation of methods to correct for measurement error in biobanks with dietary assessment

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