Inflammation in preterm and term labour and delivery

Cell-Free Fetal DNA, Telomeres, and the Spontaneous Onset of Parturition

Multiple previous reports have provided compelling support for the premise that spontaneous parturition is mediated by activation of inflammation-related signaling pathways leading to increased secretion of cytokines and chemokines, the influx of neutrophils and macrophages into the pregnant uterus, increased production of uterine activation proteins (eg, connexin-43, cyclo-oxygenase-2, oxytocin receptors, etc), activation of matrix metalloproteinases, and the release of uterotonins leading to cervical ripening, membrane rupture, and myometrial contractions. The missing link has been the fetal/placental signal that triggers these proinflammatory events in the absence of microbial invasion and intrauterine infection. This article reviews the biomedical literature regarding the increase in cell-free fetal DNA (cffDNA), which is released during apoptosis in the placenta and fetal membranes at term, the ability of apoptosis modified vertebrate DNA to stimulate toll-like receptor-9 (TLR9) leading to increased release of cytokines and chemokines, and the potential "fail-safe" role for the anti-inflammatory cytokine IL-10. This article also reviews the literature supporting the key role that telomere loss plays in regard to increasing the ability of vertebrate (including placental) DNA to stimulate TLR9, and in regard to signaling the onset of apoptosis in the placenta and fetal membranes, thereby providing a biologic clock that determines the length of gestation and the timing for the onset of parturition. In summary, this literature review provides a strong rationale for future research to test the hypothesis that telomere loss and increased cffDNA levels trigger the proinflammatory events leading to the spontaneous onset of parturition in mammals: the "cffDNA/telomere hypothesis."

Interleukin-6 controls uterine Th9 cells and CD8(+) T regulatory cells to accelerate parturition in mice

Interleukin-6 (IL6) is a determinant of the timing of parturition and birth in mice. We previously demonstrated that genetic IL6 deficiency delays parturition by ~24 h, and this is restored by administration of exogenous IL6. In this study, we have investigated whether IL6 influences the number or phenotypes of T cells or other leukocytes in uterine decidual tissue at the maternal-fetal interface. In late gestation, decidual leukocytes in Il6 null mutant (Il6(-/-)) mice exhibit an altered profile, characterized by reduced numbers of cells expressing the monocyte/macrophage marker F4/80 or the T-cell marker CD4, increased cells expressing the natural killer (NK) cell marker CD49b or the dendritic cell marker CD11c, but no change in cells expressing the neutrophil marker Ly6G. These changes are specific to late pregnancy, as similar differences in decidual leukocytes were not evident in mid-gestation Il6(-/-) mice. The IL6-regulated changes in decidual NK and dendritic cells appear secondary to local recruitment, as no comparable changes occurred in peripheral blood of Il6(-/-) mice. When exogenous IL6 was administered to restore normal timing of parturition, a partial reversal of the altered leukocyte profile was observed, with a 10% increase in the proportion of decidual CD4(+) T cells, a notable 60% increase in CD8(+) T cells including CD8(+)CD25(+)Foxp3(+) regulatory T cells and a 60% reduction in CD4(+)IL9(+) Th9 cells. Together these findings suggest that IL6-controlled accumulation of decidual CD4(+) T cells and CD8(+) regulatory T cells, with an associated decline in decidual Th9 cells, is instrumental for progressing parturition in mice.

Isolation of Leukocytes from the Human Maternal-fetal Interface

Pregnancy is characterized by the infiltration of leukocytes in the reproductive tissues and at the maternal-fetal interface (decidua basalis and decidua parietalis). This interface is the anatomical site of contact between maternal and fetal tissues; therefore, it is an immunological site of action during pregnancy. Infiltrating leukocytes at the maternal-fetal interface play a central role in implantation, pregnancy maintenance, and timing of delivery. Therefore, phenotypic and functional characterizations of these leukocytes will provide insight into the mechanisms that lead to pregnancy disorders. Several protocols have been described in order to isolate infiltrating leukocytes from the decidua basalis and decidua parietalis; however, the lack of consistency in the reagents, enzymes, and times of incubation makes it difficult to compare these results. Described herein is a novel approach that combines the use of gentle mechanical and enzymatic dissociation techniques to preserve the viability and integrity of extracellular and intracellular markers in leukocytes isolated from the human tissues at the maternal-fetal interface. Aside from immunophenotyping, cell culture, and cell sorting, the future applications of this protocol are numerous and varied. Following this protocol, the isolated leukocytes can be used to determine DNA methylation, expression of target genes, in vitro leukocyte functionality (i.e., phagocytosis, cytotoxicity, T-cell proliferation, and plasticity, etc.), and the production of reactive oxygen species at the maternal-fetal interface. Additionally, using the described protocol, this laboratory has been able to describe new and rare leukocytes at the maternal-fetal interface.

Inflammatory Signalling in Fetal Membranes: Increased Expression Levels of TLR 1 in the Presence of Preterm Histological Chorioamnionitis

Histological chorioamnionitis (HCA) is an established marker of ascending infection, a major cause of preterm birth. No studies have characterised the global change in expression of genes involved in the toll-like receptor (TLR) signalling pathways in the presence of HCA in the setting of preterm birth (pHCA). Fetal membranes were collected immediately after delivery and underwent histological staging for inflammation to derive 3 groups; term spontaneous labour without HCA (n = 9), preterm birth <34 weeks gestation without HCA (n = 8) and pHCA <34 weeks (n = 12). Profiling arrays ran in triplicate for each group were used to determine the expression of 84 genes associated with TLR signalling and screen for genes of interest (fold change >2; p<0.1). Expression of identified genes was validated individually for all samples, relative to GAPDH, using RT-PCR. Expression of TLR 1, TLR 2, lymphocyte antigen 96, interleukin 8 and Interleukin-1 receptor-associated kinase-like 2 was increased in pHCA (p<0.05). Degree of expression was positively associated with histological staging of both maternal and fetal inflammation (p<0.05). The inflammatory expression profile at the maternal/fetal interface associated with pHCA, a reflection of ascending infection, is extremely heterogeneous suggesting polymicrobial involvement with activation of a common pathway. Antagonism of TLR 1 and TLR 2 signalling in this setting warrants further assessment.

KLF5 regulates infection- and inflammation-induced pro-labour mediators in human myometrium

The transcription factor Kruppel-like factor 5 (KLF5) has been shown to associate with nuclear factor kappa B (NFκB) to regulate genes involved in inflammation. However, there are no studies on the expression and regulation of KLF5 in the processes of human labour and delivery. Thus, the aims of this study were to determine the effect of i) human labour on KLF5 expression in both foetal membranes and myometrium; ii) the pro-inflammatory cytokine interleukin 1 beta (IL1β), bacterial product flagellin and the viral dsRNA analogue poly(I:C) on KLF5 expression and iii) KLF5 knockdown by siRNA in human myometrial primary cells on pro-inflammatory and pro-labour mediators. In foetal membranes, there was no effect of term or preterm labour on KLF5 expression. In myometrium, the term labour was associated with an increase in nuclear KLF5 protein expression. Moreover, KLF5 expression was also increased in myometrial cells treated with IL1β, flagellin or poly(IC), likely factors contributing to preterm birth. KLF5 silencing in myometrial cells significantly decreased IL1β-induced cytokine expression (IL6 and IL8 mRNA expression and release), COX2 mRNA expression, and subsequent release of prostaglandins PGE2 and PGF2α. KLF5 silencing also significantly reduced flagellin- and poly(I:C)-induced IL6 and IL8 mRNA expression. Lastly, IL1β-, flagellin- and poly(I:C)-stimulated NFκB transcriptional activity was significantly suppressed in KLF5-knockout myometrial cells. In conclusion, this study describes novel data in which KLF5 is increased in labouring myometrium, and KLF5 silencing decreased inflammation- and infection-induced pro-labour mediators.

Galectins: Double-edged Swords in the Cross-roads of Pregnancy Complications and Female Reproductive Tract Inflammation and Neoplasia

Galectins are an evolutionarily ancient and widely expressed family of lectins that have unique glycan-binding characteristics. They are pleiotropic regulators of key biological processes, such as cell growth, proliferation, differentiation, apoptosis, signal transduction, and pre-mRNA splicing, as well as homo- and heterotypic cell-cell and cell-extracellular matrix interactions. Galectins are also pivotal in immune responses since they regulate host-pathogen interactions, innate and adaptive immune responses, acute and chronic inflammation, and immune tolerance. Some galectins are also central to the regulation of angiogenesis, cell migration and invasion. Expression and functional data provide convincing evidence that, due to these functions, galectins play key roles in shared and unique pathways of normal embryonic and placental development as well as oncodevelopmental processes in tumorigenesis. Therefore, galectins may sometimes act as double-edged swords since they have beneficial but also harmful effects for the organism. Recent advances facilitate the use of galectins as biomarkers in obstetrical syndromes and in various malignancies, and their therapeutic applications are also under investigation. This review provides a general overview of galectins and a focused review of this lectin subfamily in the context of inflammation, infection and tumors of the female reproductive tract as well as in normal pregnancies and those complicated by the great obstetrical syndromes.

Streptococcus agalactiae in pregnancies complicated by preterm prelabor rupture of membranes

OBJECTIVE

The main aim of this study was to evaluate the presence of Streptococcus agalactiae (S. agalactiae) in the vagina and the amniotic fluid in pregnancies complicated by preterm prelabor rupture of membranes (PPROM). The next aim was to evaluate the incidence of S. agalactiae early onset sepsis in newborns from PPROM pregnancies, with respect to the presence of S. agalactiae in the vagina and the amniotic fluid.

METHODS

Singleton gestations with PPROM between 24 + 0 and 36 + 6 were included. A vaginal swab was obtained, and amniocentesis was performed at admission. The presence of S. agalactiae in the vagina and in the amniotic fluid was assessed by culture and by real-time polymerase chain reaction, respectively.

RESULTS

In total, 336 women were included. The presence of S. agalactiae in the vaginal and amniotic fluid was found in 9% (31/336) and 1% (3/336) of women. One woman had S. agalactiae in the amniotic fluid but was negative for the presence of S. agalactiae in the vaginal fluid. Early onset neonatal sepsis developed in one newborn from pregnancies complicated by the presence of S. agalactiae in the amniotic fluid.

CONCLUSION

The presence of S. agalactiae in the vagina and amniotic fluid complicated approximately each 10th and each 100th PPROM pregnancy. Cultivation-negative findings of S. agalactiae in the vagina did not exclude the positivity of the amniotic fluid for S. agalactiae and the development of early onset sepsis in newborns.

Drugs to block cytokine signaling for the prevention and treatment of inflammation-induced preterm birth

Preterm birth (PTB) at less than 37 weeks of gestation is the leading cause of neonatal morbidity and mortality. Intrauterine infection (IUI) due to microbial invasion of the amniotic cavity is the leading cause of early PTB (<32 weeks). Commensal genital tract Ureaplasma and Mycoplasma species, as well as Gram-positive and Gram-negative bacteria, have been associated with IUI-induced PTB. Bacterial activation of Toll-like receptors and other pattern recognition receptors initiates a cascade of inflammatory signaling via the NF-κB and p38 mitogen-activated protein kinase (MAPK) signaling pathways, prematurely activating parturition. Antenatal antibiotic treatment has had limited success in preventing PTB or fetal inflammation. Administration of anti-inflammatory drugs with antibiotics could be a viable therapeutic option to prevent PTB and fetal complications in women at risk of IUI and inflammation. In this mini-review, we will discuss the potential for anti-inflammatory drugs in obstetric care, focusing on the class of drugs termed “cytokine suppressive anti-inflammatory drugs” or CSAIDs. These inhibitors work by specifically targeting the NF-κB and p38 MAPK inflammatory signaling pathways. Several CSAIDs are discussed, together with clinical and toxicological considerations associated with the administration of anti-inflammatory agents in pregnancy.

Mid-trimester maternal serum and amniotic fluid biomarkers for the prediction of preterm delivery and intrauterine growth retardation

AIM

Our purpose was to evaluate the predictive value of maternal serum and amniotic fluid biomarkers that were obtained at the time of genetic amniocentesis for preterm delivery and intrauterine growth retardation (IUGR).

METHODS

A prospective cohort analysis was conducted in 107 singleton pregnancies that underwent amniocentesis at 16-22 weeks according to standard genetic indications. Maternal blood and amniotic fluid obtained from genetic amniocentesis were tested for glucose, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), ceruloplasmin, ferritin, high-sensitivity C-reactive protein and interleukin-6 (IL-6). Ninety-four pregnancies were followed until delivery.

RESULTS

Of the 94 patients, 16 (18.1%) delivered before 37 weeks and seven (7.5%) delivered a baby below the 10th percentile for gestational age. Amniotic fluid glucose levels were significantly lower in patients with preterm delivery than term deliveries (P = 0.01). Median amniotic fluid ferritin and IL-6 levels and mean amniotic fluid ALP levels were higher in the preterm group but this difference did not reach statistical significance. Mean maternal ALP and LDH levels tended to be insignificantly higher. Only median maternal blood ferritin levels in the IUGR group were found to be higher than patients who were appropriate for gestational age (P = 0.03).

CONCLUSION

Low amniotic fluid glucose levels are associated with risk of preterm delivery, whereas high maternal blood ferritin levels increase the risk for IUGR. Although this result is significant and notable, there is not enough clinical evidence to recommend their use as a screening test for preterm delivery and IUGR in routine practice.

Umbilical cord prostaglandins in term and preterm parturition

OBJECTIVE

Prostaglandins (PGs) are considered the universal mediators of parturition. Amniotic fluid PGE2 and PGF2α concentrations increase before the onset of spontaneous labor at term, as well as during labor. This study was conducted to determine if the concentrations of umbilical cord PGE2 and PGF2α change with advancing gestational age, spontaneous labor at term, and preterm labor (with and without funisitis).

METHODS

Umbilical cord (UC) tissue samples were obtained from women (N = 158) with singleton pregnancies in the following groups: (1) term deliveries without labor (TNL; n = 20); (2) term deliveries with labor (TIL; n = 20); (3) spontaneous preterm deliveries (sPTD) with (n = 20) and without acute funisitis (n = 20); and (4) preeclampsia without labor (n = 78). The concentrations of PGs were determined in different locations of the UC. PGE2 and PGF2α were measured by specific immunoassays. Non-parametric statistics were used for analysis.

RESULTS

(1) In spontaneous preterm deliveries, the median UC PGE2 concentration was higher in cases with funisitis than in those without funisitis (233.7 pg/µg versus 87.4 pg/µg of total protein, p = 0.001); (2) the median UC PGE2 concentration in sPTD with funisitis was also higher than that obtained from samples who had undergone labor at term (233.7 pg/µg versus 116.1 pg/µg of total protein, p = 0.03); (3) the UC PGE2 and PGF2α concentration increased as a function of advancing gestational age before 36 weeks (PGE2: ρ = 0.59, p < 0.001; PGF2α: ρ = 0.39, p = 0.01), but not after 36 weeks (PGE2: ρ = -0.1, p = 0.5; PGF2α: ρ = -0.2, p = 0.2); (4) the median UC concentrations of PGE2 and PGF2α at term was similar in samples obtained from women with and without labor (PGE2: TNL 133.7 pg/µg versus TIL 116.1 pg/µg of total protein, p = 0.9; PGF2α: TNL 8.4 pg/µg versus TIL 8.1 pg/µg of total protein, p = 0.7); and (5) there was no correlation between UC PG concentration and gestational age at term pregnancy (PGE2: ρ = 0.01, p = 0.9; PGF2α: ρ = 0.07, p = 0.7).

CONCLUSIONS

(1) PGE2 concentrations in the UC are higher in the presence of acute funisitis than in the absence of this lesion; (2) spontaneous labor at term was not associated with a change in the UC concentration of PGE2 and PGF2α; and (3) the UC concentrations of PGE2 and PGF2α increased as a function of gestational age. We propose that UC PGs act as inflammatory mediators generated in the context of fetal systemic inflammation.

A novel role for GSK3 in the regulation of the processes of human labour

Preterm birth remains the largest single cause of neonatal death and morbidity. Infection and/or inflammation are strongly associated with preterm delivery. Glycogen synthase kinase 3 (GSK3) is known to be a crucial mediator of inflammation homeostasis. The aims of this study were to determine the effect of spontaneous human labour in foetal membranes and myometrium on GSK3α/β expression, and the effect of inhibition of GSK3α/β on pro-labour mediators in foetal membranes and myometrium stimulated with Toll-like receptor (TLR) ligands and pro-inflammatory cytokines. Term and preterm labour in foetal membranes was associated with significantly decreased serine phosphorylated GSK3α and β expression, and thus increased GSK3 activity. There was no effect of term labour on serine phosphorylated GSK3β expression in myometrium. The specific GSK3α/β inhibitor CHIR99021 significantly decreased lipopolysaccharide (ligand to TLR4)-stimulated pro-inflammatory cytokine gene expression and release;COX2gene expression and prostaglandin release; andMMP9gene expression and pro MMP9 release in foetal membranes and/or myometrium. CHIR99021 also decreased FSL1 (TLR2 ligand) and flagellin (TLR5 ligand)-induced pro-inflammatory cytokine gene expression and release andCOX2mRNA expression and prostaglandin release.GSK3βsiRNA knockdown in primary myometrial cells was associated with a significant decrease in IL1β and TNFα-induced pro-inflammatory cytokine and prostaglandin release. In conclusion, GSK3α/β activity is increased in foetal membranes after term and preterm labour. Pharmacological blockade of the kinase GSK3 markedly reduced pro-inflammatory and pro-labour mediators in human foetal membranes and myometrium, providing a possible therapeutics for the management of preterm labour.

Differences in inflammatory markers between nulliparous women admitted to hospitals in preactive vs active labor

OBJECTIVE

To determine whether labor-associated inflammatory markers differ between low-risk, nulliparous women in preactive vs active labor at hospital admission and over time.

STUDY DESIGN

Prospective comparative study of low-risk, nulliparous women with spontaneous labor onset at term (n = 118) sampled from 2 large Midwestern hospitals. Circulating concentrations of inflammatory markers were measured at admission and again 2 and 4 hours later: namely, neutrophil, and monocyte counts; and serum inflammatory cytokines (interleukin -1β, interleukin-6, tumor necrosis factor-α, interleukin-10) and chemokines (interleukin-8). Biomarker concentrations and their patterns of change over time were compared between preactive (n = 63) and active (n = 55) labor admission groups using Mann-Whitney U tests.

RESULTS

Concentrations of interleukin-6 and interleukin-10 in the active labor admission group were significantly higher than concentrations in the preactive labor admission group at all 3 time points. Neutrophil levels were significantly higher in the active group at 2 and 4 hours after admission. The rate of increase in neutrophils and interleukin-10 between admission and 2 hours later was faster in the active group (P < .001 and P = .003, respectively).

CONCLUSION

Circulating concentrations of several inflammatory biomarkers are higher and their rate of change over time since admission is faster among low-risk, nulliparous women admitted to hospitals in active labor, as compared with those admitted in preactive labor. More research is needed to determine if progressive changes in inflammatory biomarkers might be a useful adjunct to improving the assessment of labor progression and determining the optimal timing of labor admission.

Lipopolysaccharides upregulate calcium concentration in mouse uterine smooth muscle cells through the T-type calcium channels

Infection is a significant cause of preterm birth. Abnormal changes in intracellular calcium signals are the ultimate triggers of early uterine contractions that result in preterm birth. T‑type calcium channels play an important role in the pathogenesis of cancer, as well as endocrine and cardiovascular diseases. However, there are limited studies on their role in uterine contractions and parturition. In the present study, mouse uterine smooth muscle cells were isolated and treated with lipopolysaccharides (LPS) to mimic the microenvironment of uterine infection in vitro to investigate the role of T‑type calcium channels in the process of infection‑induced preterm birth. The results from quantitative polymerase chain reaction and western blot analysis showed that LPS significantly induced the expression of the Cav3.1 and Cav3.2 subtypes of T‑type calcium channels. Measurements of intracellular calcium concentration showed a significant increase in response to LPS. However, these effects can be reversed by T‑type calcium channel blockers. Western blot analysis further indicated that LPS induced the activation of the nuclear factor (NF)‑κB signaling pathway, and endothelin‑1 (ET‑1) was significantly upregulated, whereas NF‑κB inhibitors significantly inhibited the LPS‑induced upregulation of Cav3.1, Cav3.2 and ET‑1 expression. In addition, ET‑1 directly induced Cav3.1 and Cav3.2 expression, whereas ET‑1 antagonists inhibited the LPS‑induced upregulation of Cav3.1 and Cav3.2 expression. In conclusion, the present study demonstrates that infection triggers the upregulation of T‑type calcium channels and promotes calcium influx. This process relies on the activation of the NF‑κB/ET‑1 signaling pathway. The T‑type calcium channel is expected to become an effective target for the prevention of infection‑induced preterm birth.

Longitudinal changes in serum proinflammatory markers across pregnancy and postpartum: effects of maternal body mass index

BACKGROUND

The maternal immune system undergoes substantial changes to support healthy pregnancy. Although obesity is a primary driver of inflammation and predictive of perinatal complications, additive effects of pregnancy and obesity on changes in inflammatory processes are not well delineated.

METHODS

This study examined serum proinflammatory markers interleukin(IL)-6, IL-8, tumor necrosis factor (TNF)-α, IL-1β, and C-reactive protein (CRP) during each trimester of pregnancy and 4-6 weeks postpartum among 57 women.

RESULTS

Overall, IL-6 showed an increasing trend across pregnancy and significant increase at postpartum. Similarly, TNF-α increased significantly across gestation, with a further increase at postpartum. Both IL-8 and IL-1β showed a U-shaped curve, decreasing from early to later pregnancy, and increasing at postpartum. Finally, serum CRP decreased significantly across pregnancy, with further decreases at postpartum. Maternal obesity predicted higher IL-6 at each study visit. Obese women showed a trend toward elevated serum CRP during pregnancy, and significantly higher levels at postpartum.

DISCUSSION

The course of pregnancy and postpartum is characterized by significant changes in serum proinflammatory mediators. Obese women show elevations in serum proinflammatory markers relative to normal weight women during pregnancy and postpartum. Further research is needed to determine the extent to which obesity-induced inflammation affects maternal and fetal health.

A clear and present danger: inflammasomes DAMPing down disorders of pregnancy

BACKGROUND

When the normal progression of pregnancy is threatened, inflammatory processes are often amplified in order to minimize detrimental effects and eliminate noxious agents. Inflammasomes are unique, intracellular, multiprotein assemblies that enable caspase-1 mediated proteolytic processing of the proinflammatory cytokine interleukin-1β, levels of which are elevated in some forms of preterm birth and maternal metabolic disorders.

METHODS

A comprehensive review based on a search of PubMed and Medline for terms and combinations of terms incorporating 'inflammation', 'inflammasome', 'pregnancy', 'preterm birth', 'pre-eclampsia', 'interleukin-1', 'caspase-1' and others selected to capture key articles.

RESULTS

In the decade since the discovery of the inflammasome, between January 2002 and June 2014 over 2200 articles have been published. Articles in the reproductive field are scarce but there is clear evidence for a role of the inflammasome axis in pregnancy, preterm birth and the maternal metabolic syndrome.

CONCLUSION

Further investigations on the inflammasome in pregnancy are needed in order to elucidate the biology of this unique structure in reproduction. Coordination of maternal, fetal and placental aspects of inflammasome function will potentially yield new information on the detection and transduction of host and non-host signals in the inflammatory response.

In vivo experiments reveal the good, the bad and the ugly faces of sFlt-1 in pregnancy

Objective

Soluble fms-like tyrosine kinase (sFlt)-1-e15a, a primate-specific sFlt-1-isoform most abundant in the human placenta in preeclampsia, can induce preeclampsia in mice. This study compared the effects of full-length human (h)sFlt-1-e15a with those of truncated mouse (m)sFlt-1(1-3) used in previous preeclampsia studies on pregnancy outcome and clinical symptoms in preeclampsia.

Methods

Mice were injected with adenoviruses or fiber-mutant adenoviruses overexpressing hsFlt-1-e15a, msFlt-1(1-3) or control GFP under the CMV or CYP19A1 promoters on gestational day 8 (GD8) and GD11. Placentas and pups were delivered by cesarean section, and dams were monitored postpartum. Blood pressure was telemetrically recorded. Urine samples were collected with cystocentesis and examined for albumin/creatinine ratios. Tissue specimens were evaluated for transgene as well as endogenous mFlt-1 and msFlt-1-i13 expression. H&E-, Jones- and PAS-stained kidney sections were histopathologically examined. Placental GFP expression and aortic ring assays were investigated with confocal microscopy.

Results

Mean arterial blood pressure (MAP) was elevated before delivery in hsFlt-1-e15a-treated mice compared to controls (GD18: ΔMAP = 7.8 mmHg, p = 0.009), while ΔMAP was 12.8 mmHg (GD18, p = 0.005) in msFlt-1(1-3)-treated mice. Urine albumin/creatinine ratio was higher in hsFlt-1-e15a-treated mice than in controls (GD18, p = 0.04; PPD8, p = 0.03), and msFlt-1(1-3)-treated mice had marked proteinuria postpartum (PPD8, p = 4×10⁻⁵). Focal glomerular changes were detected in hsFlt-1-e15a and msFlt-1(1-3)-treated mice. Aortic ring microvessel outgrowth was decreased in hsFlt-1-e15a (p = 0.007) and msFlt-1(1-3)-treated (p = 0.02) mice. Full-length msFlt-1-i13 expression was unique for the placenta. In hsFlt-1-e15a-treated mice, the number of pups (p = 0.046), total weight of living pups (p = 0.04) and maternal weights (p = 0.04) were higher than in controls. These differences were not observed in truncated msFlt-1(1-3)-treated mice.

Conclusions

Truncated msFlt-1(1-3) simulated the preeclampsia-promoting effects of full-length hsFlt-1. MsFlt-1(1-3) had strong effect on maternal endothelium but not on placentas and embryos. In contrast, hsFlt-1-e15a induced preeclampsia-like symptoms; however, it also increased litter size. In accord with the predominant placental expression of hsFlt-1-e15a and msFlt-1-i13, full-length sFlt-1 may have a role in the regulation of embryonic development. These observations point to the difference in the biological effects of full-length and truncated sFlt-1 and the changes in the effect of full-length sFlt-1 during pregnancy, and may have important implications in the management of preeclampsia.

Oxidative stress damage as a detrimental factor in preterm birth pathology

Normal term and spontaneous preterm births (PTB) are documented to be associated with oxidative stress (OS), and imbalances in the redox system (balance between pro- and antioxidant) have been reported in the maternal-fetal intrauterine compartments. The exact mechanism of labor initiation either at term or preterm by OS is still unclear, and this lack of understanding can partially be blamed for failure of antioxidant supplementation trials in PTB prevention. Based on recent findings from our laboratory, we postulate heterogeneity in host OS response. The physiologic (at term) and pathophysiologic (preterm) pathways of labor are not mediated by OS alone but by OS-induced damage to intrauterine tissues, especially fetal membranes of the placenta. OS damage affects all major cellular elements in the fetal cells, and this damage promotes fetal cell senescence (aging). The aging of the fetal cells is predominated by p38 mitogen activated kinase (p38MAPK) pathways. Senescing cells generate biomolecular signals that are uterotonic, triggering labor process. The aging of fetal cells is normal at term. However, aging is premature in PTB, especially in those PTBs complicated by preterm premature rupture of the membranes, where elements of redox imbalances and OS damage are more dominant. We postulate that fetal cell senescence signals generated by OS damage are likely triggers for labor. This review highlights the mechanisms involved in senescence development at term and preterm by OS damage and provides insight into novel fetal signals of labor initiation pathways.

Chemotactic activity of gestational tissues through late pregnancy, term labor, and RU486-induced preterm labor in Guinea pigs

PROBLEM

Is increased leukocyte chemotactic activity (CA) from gestational tissues necessary for term or preterm labor in guinea pigs?

METHOD OF STUDY

Tissue extracts were prepared from pregnant guinea pig decidua-myometrium, cervix, fetal membranes (amniochorion), and placenta during early third trimester (n = 8), term not in labor (TNL, n = 5), and term spontaneous labor (TL, n = 6), RU486-induced preterm labor (PTL, n = 6), or controls (cPTL, n = 5). Leukocyte CA was assessed using a modified Boyden chamber assay. Extract chemokine and maternal progesterone concentrations were quantified by enzyme immunoassay.

RESULTS

Only the extracts from amniochorion demonstrated increased CA through late gestation and labor. In contrast, CA was decreased in extracts from amniochorion and cervix from animals after RU486-induced PTL. Maternal progesterone concentrations remained high in all groups.

CONCLUSION

Leukocyte CA of intrauterine tissues is increased in term spontaneous labor. However, RU486-induced preterm labor occurs in the absence of increased CA.

Myeloid derived suppressor cells are present at high frequency in neonates and suppress in vitro T cell responses

Over 4 million infants die each year from infections, many of which are vaccine-preventable. Young infants respond relatively poorly to many infections and vaccines, but the basis of reduced immunity in infants is ill defined. We sought to investigate whether myeloid-derived suppressor cells (MDSC) represent one potential impediment to protective immunity in early life, which may help inform strategies for effective vaccination prior to pathogen exposure. We enrolled healthy neonates and children in the first 2 years of life along with healthy adult controls to examine the frequency and function of MDSC, a cell population able to potently suppress T cell responses. We found that MDSC, which are rarely seen in healthy adults, are present in high numbers in neonates and their frequency rapidly decreases during the first months of life. We determined that these neonatal MDSC are of granulocytic origin (G-MDSC), and suppress both CD4+ and CD8+ T cell proliferative responses in a contact-dependent manner and gamma interferon production. Understanding the role G-MDSC play in infant immunity could improve vaccine responsiveness in newborns and reduce mortality due to early-life infections.

Leptospira interrogans induces uterine inflammatory responses and abnormal expression of extracellular matrix proteins in dogs

Leptospira interrogans (L. interrogans), a worldwide zoonosis, infect humans and animals. In dogs, four syndromes caused by leptospirosis have been identified: icteric, hemorrhagic, uremic (Stuttgart disease) and reproductive (abortion and premature or weak pups), and also it caused inflammation. Extracellular matrix (ECM) is a complex mixture of matrix molecules that is crucial to the reproduction. Both inflammatory response and ECM are closed relative to reproductive. The aim of this study was to clarify how L. interrogans affected the uterus of dogs, by focusing on the inflammatory responses, and ECM expression in dogs uterine tissue infected by L. interrogans. In the present study, 27 dogs were divided into 3 groups, intrauterine infusion with L. interrogans, to make uterine infection, sterile EMJH, and normal saline as a control, respectively. The uteruses were removed by surgical operation in 10, 20, and 30 days, respectively. The methods of histopathological analysis, ELISA, Western blot and qPCR were used. The results showed that L. interrogans induced significantly inflammatory responses, which were characterized by inflammatory cellular infiltration and high expression levels of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) in uterine tissue of these dogs. Furthermore, L. interrogans strongly down-regulated the expression of ECM (collagens (CL) IV, fibronectins (FN) and laminins (LN)) in mRNA and protein levels. These data indicated that strongly inflammatory responses, and abnormal regulation of ECM might contribute to the proliferation of dogs infected by L. interrogans.

Polymorphism in the ADRB2 gene explains a small portion of intersubject variability in pain relative to cervical dilation in the first stage of labor

BACKGROUND

Variability in labor pain has been associated with demographic, clinical, and psychological factors. Polymorphisms of the β2-adrenergic receptor gene (ADRB2) influence sensitivity to experimental pain in humans and are a risk factor for chronic pain. The authors hypothesized that polymorphisms in ADRB2 may influence labor pain.

METHODS

After Institutional Review Board approval and written informed consent, the authors prospectively obtained hourly pain reports from 233 nulliparous parturients during the first stage of labor, of which 199 were included in the current analysis. DNA from blood samples was genotyped at polymorphisms in the genes for the β2-adrenergic receptor, the μ opioid receptor subtype 1, catechol-O-methyltransferase, fatty acid amide hydrolase, and the oxytocin receptor. Labor pain as a function of cervical dilation was modeled with previously described methods. Patient covariates, ADRB2 genotype, and obstetrical and anesthesia treatment were evaluated as covariates in the model.

RESULTS

Labor pain more rapidly became severe in parturients heterozygous or homozygous for the G allele at rs1042714 in the ADRB2 gene. Labor pain increased more rapidly after artificial rupture of membranes, augmentation with oxytocin, and in younger women. Inclusion of covariates explained approximately 10% of the variability between subjects. ADRB2 genotype explained less than 1% of the intersubject variability.

CONCLUSION

ADRB2 genotype correlates with labor pain but explained less than 1% of the intersubject variance in the model.

Increased neopterin level and chitotriosidase activity in pregnant women with threatened preterm labor

OBJECTIVES

To determine whether the cellular inflammatory markers of activated macrophages, neopterin (NEO), chitotriosidase activity and the acute-phase inflammatory marker C-reactive protein (CRP) are elevated in pregnancy with threatened preterm labor (TPL).

METHODS

Thirty-two pregnant women with TPL and 32 women with uncomplicated pregnancy (UP) were included this study. The primary aim was to compare the NEO, chitotriosidase activity and CRP levels between women with TPL and women with UP.

RESULTS

NEO levels were all significantly elevated in patients with TPL compared to UP (median 25-75%; 9.61 [8.47-12.29] versus 4.46 [3.59-6.92], respectively; p < 0.001). Chitotriosidase activity was significantly elevated in pregnant women with TPL compared to UP (median 25-75%; 59.00 [38.00-87.25] versus 43.50 [23.25-65.25], respectively; p = 0.036). However, CRP levels were not different in women with TPL compared to UP (p = 0.573). Furthermore, a significant moderate negative correlation was found between delivery week and NEO level (r = -0.557, p = 0.001). However, a significant correlation was not seen between delivery week and chitotriosidase activity (r = -0.042, p = 0.741).

CONCLUSIONS

Inflammatory markers such as NEO and chitotriosidase activity, which are markers of macrophages, are more elevated in pregnant women with TPL than in women with UP. These data suggest that there are striking increases in inflammation and cellular immune activation in TPL.

Abnormal cervical cancer screening in pregnancy and preterm delivery

BACKGROUND

Preterm delivery is a major cause of neonatal morbidity and mortality. Human papillomavirus (HPV) infection is common in reproductive-aged women. We hypothesised that abnormal cervical cancer screening tests, as a proxy for HPV infection, would be associated with preterm delivery.

METHODS

We conducted a retrospective cohort study of women delivering liveborn singletons beyond 20 weeks gestation, who had a Papanicolaou (Pap) test within 1 year prior to delivery. Women with abnormal Pap or positive high-risk HPV tests, classified as having 'abnormal screening', were compared with women classified as having 'normal screening' in bivariate analysis for overall preterm delivery at less than 37 weeks gestation. Using Poisson regression, we report unadjusted (RR) and adjusted (aRR) risk ratios for spontaneous preterm delivery due to preterm labour and preterm premature rupture of membranes.

RESULTS

Among 2686 women meeting criteria for analysis, 213 (8%) had abnormal screening. Women with abnormal screening, compared with normal screening, were not more likely to deliver preterm (12.2% vs. 9.8%, RR 1.3 [95% confidence interval (CI) 0.9, 1.8], aRR 1.2 [95% CI 0.8, 1.7]). Women with abnormal screening, however, were at greater risk for spontaneous preterm delivery in unadjusted and adjusted analysis (8.9% vs. 4.5%; RR 2.0 [95% CI 1.2, 3.2], aRR 1.8 [95% CI 1.1, 2.9]).

CONCLUSIONS

There was no difference in risk of overall preterm delivery in women with abnormal compared with normal cervical cancer screening tests. Our data suggest, however, that abnormal screening in pregnancy may be associated with spontaneous preterm delivery.

Immune cells in term and preterm labor

Labor resembles an inflammatory response that includes secretion of cytokines/chemokines by resident and infiltrating immune cells into reproductive tissues and the maternal/fetal interface. Untimely activation of these inflammatory pathways leads to preterm labor, which can result in preterm birth. Preterm birth is a major determinant of neonatal mortality and morbidity; therefore, the elucidation of the process of labor at a cellular and molecular level is essential for understanding the pathophysiology of preterm labor. Here, we summarize the role of innate and adaptive immune cells in the physiological or pathological activation of labor. We review published literature regarding the role of innate and adaptive immune cells in the cervix, myometrium, fetal membranes, decidua and the fetus in late pregnancy and labor at term and preterm. Accumulating evidence suggests that innate immune cells (neutrophils, macrophages and mast cells) mediate the process of labor by releasing pro-inflammatory factors such as cytokines, chemokines and matrix metalloproteinases. Adaptive immune cells (T-cell subsets and B cells) participate in the maintenance of fetomaternal tolerance during pregnancy, and an alteration in their function or abundance may lead to labor at term or preterm. Also, immune cells that bridge the innate and adaptive immune systems (natural killer T (NKT) cells and dendritic cells (DCs)) seem to participate in the pathophysiology of preterm labor. In conclusion, a balance between innate and adaptive immune cells is required in order to sustain pregnancy; an alteration of this balance will lead to labor at term or preterm.

Self-rated health among pregnant women: associations with objective health indicators, psychological functioning, and serum inflammatory markers

BACKGROUND

Biobehavioral correlates of self-rated health in pregnancy are largely unknown.

PURPOSE

The goals of this study were to examine, in pregnant women, associations of self-rated health with (1) demographics, objective health status, health behaviors, and psychological factors, and (2) serum inflammatory markers.

METHODS

In the second trimester of pregnancy, 101 women provided a blood sample, completed measures of psychosocial stress, health status, and health behaviors, and received a comprehensive periodontal examination.

RESULTS

The following independently predicted poorer self-rated health: (1) greater psychological stress, (2) greater objective health diagnoses, (3) higher body mass index, and (4) past smoking (versus never smoking). Poorer self-rated health was associated with higher serum interleukin-1β (p = 0.02) and marginally higher macrophage migration inhibitory factor (p = 0.06). These relationships were not fully accounted for by behavioral/psychological factors.

CONCLUSIONS

This study provides novel data regarding factors influencing subjective ratings of health and the association of self-rated health with serum inflammatory markers in pregnant women.

Inhibition of infection-mediated preterm birth by administration of broad spectrum chemokine inhibitor in mice

Preterm birth (PTB) is the single most important cause of perinatal and infant mortality worldwide. Maternal infection can result in PTB. We investigated the ability of a Broad Spectrum Chemokine Inhibitor (BSCI) to prevent infection-induced PTB in mice. PTB was initiated in pregnant mice by intraperitoneal injection of lipopolysaccharide (LPS; 50 μg). Half the mice received BSCI (10 mg/kg) 24 hrs prior to and immediately before LPS administration. The impact of LPS alone or LPS plus BSCI was assessed on (i) injection-to-delivery interval, foetal survival rate, placental and neonates' weight; (ii) amniotic fluid and maternal plasma cytokine levels (by Luminex assay); foetal and maternal tissue cytokine gene expression levels (by Real-Time RT-PCR); (iii) immune cells infiltration into the uterine tissue (by stereological immunohistochemistry). Pre-treatment with BSCI (i) decreased LPS-induced PTB (64% versus 100%, P < 0.05); (ii) significantly attenuated cytokine/chemokine expression in maternal tissues (plasma, liver, myometrium, decidua); (iii) significantly decreased neutrophil infiltration in the mouse myometrium. BSCI-treated mice in which PTB was delayed till term had live foetuses with normal placental and foetal weight. BSCI represents a promising new class of therapeutics for PTB. In a mouse model of preterm labour, BCSI suppresses systemic inflammation in maternal tissues which resulted in the reduced incidence of LPS-mediated PTB. These data provide support for efforts to target inflammatory responses as a means of preventing PTB.

Birth outcomes in women with inflammatory bowel disease: effects of disease activity and drug exposure

BACKGROUND

Ulcerative colitis (UC) and Crohn's disease (CD) have been associated with increased risks of adverse birth outcomes. Disease activity and drug exposure may contribute to the association.

METHODS

A cohort from the Swedish health registers including 470,110 singleton births in Sweden from July 2006 to December 2010; 1833 to women with UC and 1220 to women with CD. Birth outcomes for women with UC and CD were compared with outcomes among those without disease. Diseased women were categorized by drug exposure, need of surgery, and hospital admissions as (1) no disease activity and (2) stable or (3) flaring disease. Logistic regression was used to calculate odds ratios with adjustments (aOR) for maternal age, parity, smoking status, body mass index, and comorbidity.

RESULTS

There were increased risks of preterm birth for both UC (aOR, 1.78; 95% confidence interval [CI], 1.49-2.13) and CD (aOR, 1.65; 95% CI, 1.33-2.06). Risks were more pronounced in women with flaring disease during pregnancy. Risks of small for gestational age, low Apgar score, and hypoglycemia were also increased. The risk of stillbirth was elevated in women with CD, particularly among those with flaring disease (aOR, 4.48; 95% CI, 1.67-11.90). Thiopurine exposure increased risks for preterm birth, both in women with stable (aOR, 2.41; 95% CI, 1.05-5.51) and with flaring disease (aOR, 4.90; 95% CI, 2.76-8.69).

CONCLUSIONS

Women with UC and CD are at increased risk of adverse birth outcomes, such as stillbirth, growth restriction, and preterm birth, particularly when they suffer from flares throughout pregnancy. Thiopurine exposure seems to further increase risks, independently of disease activity.

Early elevations of the complement activation fragment C3a and adverse pregnancy outcomes

OBJECTIVE

To estimate whether elevations of complement C3a early in pregnancy are predictive of the subsequent development of adverse pregnancy outcomes.

METHODS

A plasma sample was obtained from each enrolled pregnant woman before 20 weeks of gestation. The cohort (n=1,002) was evaluated for the development of adverse pregnancy outcomes defined as hypertensive diseases of pregnancy (gestational hypertension or preeclampsia), preterm birth (before 37 weeks of gestation), premature rupture of the membranes, pregnancy loss (during the embryonic and fetal period), intrauterine growth restriction, and the composite outcome of any adverse outcome.

RESULTS

One or more adverse pregnancy outcomes occurred in 211 (21%) of the cohort. The mean levels (ng/mL) of C3a in early pregnancy were significantly (P=<.001) higher among women with one or more adverse outcomes (858±435) compared with women with an uncomplicated pregnancy (741±407). Adjusted for parity and prepregnancy body mass index, women with levels of C3a in the upper quartile in early pregnancy were three times more likely to have an adverse outcome later in pregnancy compared with women in the lowest quartile (95% confidence interval, 1.8-4.8; P<.001). The link between early elevated C3a levels and adverse pregnancy outcomes was driven primarily by individual significant (P<.05) associations of C3a with hypertensive diseases of pregnancy, preterm birth, and premature rupture of the membranes.

CONCLUSION

Elevated C3a as early as the first trimester of pregnancy is an independent predictive factor for adverse pregnancy outcomes, suggesting that complement-related inflammatory events in pregnancy contribute to the subsequent development of poor outcomes at later stages of pregnancy.

LEVEL OF EVIDENCE

II.

Preeclampsia is associated with a deficiency of lipoxin A4, an endogenous anti-inflammatory mediator

OBJECTIVE

To test whether lipoxin A4 (LXA4) deficiency results in preeclampsia.

DESIGN

Prospective experimental study.

SETTING

Patient and animal research facilities.

ANIMAL(S)

Sprague-Dawley rats.

INTERVENTION(S)

We measured LXA4 and its biosynthetic enzymes, blocked the LXA4 signaling pathway, treated experimental rats with preeclampsia with LXA4, and detected inflammatory factors, FPR2/ALX, and 11β-HSD2 to systematically test whether lack of LXA4 results in preeclampsia.

MAIN OUTCOME MEASURE(S)

We measured serum levels of LXA4 and inflammatory factors using enzyme-linked immunosorbent assay; detected LXA4 biosynthetic enzymes, inflammatory factors, FPR2/ALX, and 11β-HSD2 mRNA expression using reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time RT-PCR; and localized protein expression using immunohistochemistry.

RESULT(S)

FPR2/ALX and LXA4 and its biosynthetic enzymes were found to be decreased in women with preeclampsia. Replenishing LXA4 improved the symptoms of lipopolysaccharide-induced rats with preeclampsia, while blocking LXA4 signaling resulted in preeclampsia. LXA4 significantly reduced interleukin-6 (IL-6), tumor necrosis factor-α, and IFN-γ but increased IL-10, LXA4 up-regulated 11β-HSD2.

CONCLUSION(S)

A deficiency of LXA4 may result in preeclampsia, which might be ascribed to a reduction in inflammation response, oxidative stress, and regulation of 11β-HSD2.

Effect of propofol on prostaglandin E2 production and prostaglandin synthase-2 and cyclooxygenase-2 expressions in amniotic membrane cells

PURPOSE

Surgery during pregnancy can be a cause of preterm labor or birth, possibly resulting from anesthetic agents or direct effects of surgery. This study was aimed to investigate the effect of propofol on uterine contractility by examining prostaglandin E2 (PGE2) production and the expression of PGE synthase 2 (PGES2) and cyclooxygenase-2 (COX-2) in amniotic membrane cells.

METHODS

Amniotic membranes were collected from healthy full-term women who underwent cesarean section at 37-40 weeks of gestation. The amniotic cells were cultured in α-modified-Eagle's medium with 10% fetal bovine serum for 24 h at 5% CO2 in a 37 °C incubator. Then, various doses of propofol (0.01-10 μg/ml) were used for treatment for 3 h. PGE2 concentrations in conditioned media were evaluated using ELISA. PGES2 and COX-2 expression were examined using RT-PCR and Western blot. Cell viability and apoptosis were examined by MTT, ATP assays, and the TUNEL method.

RESULTS

PGE2 production significantly decreased at 0.1 and 1.0 μg/ml propofol concentrations compared to controls. COX-2 and PGES2 mRNA expression was decreased in a dose-dependent manner with a significant difference at 0.1 μg/ml propofol compared to controls. The protein expression of COX-2 showed a similar result to mRNA expression, but protein expression of PGES2 was not significantly decreased. No effect of propofol was found in cell viability.

CONCLUSIONS

This study showed that propofol reduced the production of PGE2 and the expression of COX-2 and PGES2 without affecting cell viability.

Differential expression of AP-1 proteins in human myometrium after spontaneous term labour onset

OBJECTIVES

The aims of this study were (i) to determine the localisation of activator protein (AP)-1 family members (cFos, FosB, cJun, JunB and JunD) in human myometrium; and (ii) to determine the effect of human term labour on the expression of AP-1 family of transcription factors in myometrium.

STUDY DESIGN

This localised the AP-1 family members cFos, FosB, cJun, JunB and JunD in human myometrium was performed by immunohistochemistry. The effect of term labour on the expression of these family members at the mRNA and protein level was assessed by qRT-PCR and Western blotting, respectively. The effect of pro-inflammatory stimuli on AP-1 transcriptional activity was assessed using a luciferase assay in primary human myometrial cells.

RESULTS

Immunohistochemical expression of cFos, FosB, cJun, JunB and JunD were all present in human myometrial tissue and displayed cytoplasmic staining. FosB and JunD also displayed nuclear staining. Term labour was associated with an increase in cFos and JunB mRNA and protein expression. On the other hand, JunD mRNA and protein expression was decreased with labour. FosB mRNA was increased with labour, but there was no change at the protein level. There was no change in cJun mRNA or protein expression. AP-1 transcriptional activity was increased in human myometrial cells by the pro-inflammatory cytokine TNF-α. There was, however, no effect of the bacterial products lipopolysaccharide (LPS; TLR4 ligand), iE-DAP (NOD1 ligand), MDP (NOD2 ligand), FSL-1 (TLR2 ligand) or flagellin (TLR5 ligand) on AP-1 transcriptional activity.

CONCLUSION

This study shows that human labour is associated with changes in AP-1 family members. Further studies are required to determine the exact role of the AP-1 family members in myometrium.

Preterm labour: association between labour physiology, tocolysis and prevention

INTRODUCTION

In developed countries, preterm birth is the major cause of perinatal morbidity, mortality and the most important public health problem in the obstetric field. In the past decades, an increasing trend has been observed regardless of the great efforts focussed on the improvement of our understanding of the physiopathological mechanisms behind preterm labour (PTL) and the improvement in the use of tocolytic drugs.

AREAS COVERED

In this review, the authors focus on some points of the physiopathology of labour in order to understand the rationality behind the different management approaches developed for the PTL syndrome.

EXPERT OPINION

There is a need to develop new tools for the treatment of patients with PTL. Research focussed on improving tocolysis, the physiology of labour and pathological processes involved in PTL would afford new approaches for the treatment of PTL, allowing clinicians to provide integrative solutions for this multifactorial disease. Recently, the prophylactic use of progesterone pessary and cerclage in women with high risk of premature labour has been reported to reduce the incidence of premature births and improve neonatal outcomes. These results highlight the importance of prediction models in order to establish preventative strategies early in pregnancy.

Preterm birth and single nucleotide polymorphisms in cytokine genes

Preterm birth (PTB) is an important issue in neonates because of its complications as well as high morbidity and mortality. The prevalence of PTB is approximately 12-13% in USA and 5-9% in many other developed countries. China represents 7.8% (approximately one million) of 14.9 million babies born prematurely annually worldwide. The rate of PTB is still increasing. Both genetic susceptibility and environmental factors are the major causes of PTB. Inflammation is regarded as an enabling characteristic factor of PTB. The aim of this review is to summarize the current literatures to illustrate the role of single nucleotide polymorphisms (SNPs) of cytokine genes in PTB. These polymorphisms are different among different geographic regions and different races, thus different populations may have different risk factors of PTB. SNPs affect the ability to metabolize poisonous substances and determine inflammation susceptibility, which in turn has an influence on reproduction-related risks and on delivery outcomes after exposure to environmental toxicants and pathogenic organisms.

Inflammatory markers in the second trimester prior to clinical onset of preeclampsia, intrauterine growth restriction, and spontaneous preterm birth

Low-grade inflammation has been associated with pregnancy complications including preeclampsia (PE), intrauterine growth restriction (IUGR), and spontaneous preterm birth (SPB). In an unmatched, nested case-control study, we assessed the possible predictive association of maternal C-reactive protein (CRP), interferon-γ-inducible protein 10 (IP-10), and soluble urokinase plasminogen activator receptor (suPAR) in second trimester plasma samples in relation to later development of PE (n = 29), IUGR (n = 53), and SPB (n = 9). Inflammatory marker levels in these groups were compared to normotensive healthy pregnant controls (n = 127). We found no statistically significant difference in CRP, IP-10, or suPAR in second trimester plasma samples from pregnant women with later PE, IUGR, and SPB when compared to normotensive healthy controls. Second trimester plasma samples of CRP, IP-10, and suPAR cannot be used as a prognostic marker for PE, IUGR, and SPB.

Is Infant Immunity Actively Suppressed or Immature?

Almost 7 million children under the age 5 die each year, and most of these deaths are attributable to vaccine-preventable infections. Young infants respond poorly to infections and vaccines. In particular, dendritic cells secrete less IL-12 and IL-18, CD8^pos T cells and NK cells have defective cytolysis and cytokine production, and CD4^pos T cell responses tend to bias towards a Th2 phenotype and promotion of regulatory T cells (T_regs). The basis for these differences is not well understood and may be in part explained by epigenetic differences, as well as immaturity of the infant's immune system. Here we present a third possibility, which involves active suppression by immune regulatory cells and place in context the immune suppressive pathways of mesenchymal stromal cells (MSC), myeloid-derived suppressor cells (MDSC), CD5^pos B cells, and T_regs. The immune pathways that these immune regulatory cells inhibit are similar to those that are defective in the infant. Therefore, the immune deficiencies seen in infants could be explained, in part, by active suppressive cells, indicating potential new avenues for intervention.

Pentraxin-3 concentration in the amniotic fluid of women at term, in spontaneous preterm labor and when not in labor

OBJECTIVE

To evaluate the concentration of PTX3 in amniotic fluid (AF) during the final weeks of normal pregnancies and in pregnancies complicated by preterm delivery (PTD).

STUDY DESIGN

A cross-sectional study was conducted with 95 pregnant women followed to term and 25 who presented with PTD. Samples of AF from all patients were obtained during cesarean section and the PTX3 concentration was determined by enzyme immunoassay (ELISA). Maternal characteristics were compared by ANOVA and the Kruskal-Wallis and Chi square tests. Comparison between PTX3 concentrations in the "PTD in labor" and "PTD not in labor" groups were performed using the Mann-Whitney test. A p value <0.05 was considered statistically significant.

RESULTS

Regarding term pregnancies, PTX3 concentrations were not statistically different across the period studied (37 weeks to 40 weeks). Among preterm pregnancies, those in preterm labor (PTL) presented higher PTX3 levels than those not in labor (p=0.001) and the risk of occurrence of PTL increased by 1% with a rise of 1pg/mL in PTX3.

CONCLUSION

PTX3 is a physiological constituent of the AF, and its concentration is elevated in the presence of spontaneous PTL, reinforcing the theory that PTX3 plays a role in the innate immune response during gestational complications associated with infectious/inflammatory conditions.

Progesterone, inflammation and preterm labor

The initiation of human parturition is not fully understood to date. The data from animal experiments demonstrate that the primary impulse for the initiation of physiological labor arises from the fetal hypothalamo-pituitary-adrenal axis (HPA). HPA is responsible for the stimulation of steroid synthesis and prostaglandin production and, in turn, the cervical dilation and the beginning of myometrial contractions. Animal experiments, however, are only partly suitable for understanding the mechanism of human labor due to substantial species-specificity. In human, the changing levels of placental CRH control the production of fetal and placental steroids. The fundamental pathogenic manifestation of spontaneous preterm labor is inflammation and similar processes also underlie the full term one. While in full term labor it is not yet precisely known what starts this process, in the preterm one, several factors have been discussed like infection, uteroplacental ischemia, and hormonal abnormalities (progesterone- or CRH-related). Inflammatory processes affect both the mother and the fetus. Fetal inflammatory response (FIRS), which can be expected for children born preterm, is frequently associated with long-term complications, in particular neurological and pulmonary. Research in this field is therefore aimed at predicting preterm labor, and on predicting the fetal inflammatory response. The role of progesterone and its receptors in the pathophysiology of preterm labor are likewise intensively studied. Clinical results on the use of additive doses of progesterone in secondary prevention of preterm labor and current experimental studies point to progesterone and its receptors playing a key role in the pathophysiology of preterm labor. This article is part of a Special Issue entitled 'Pregnancy and Steroids'.

Inflammatory response in maternal serum during preterm labour

Preterm birth (PTB), defined as a delivery before 37 weeks of gestation, is the leading cause of perinatal morbidity and mortality worldwide. Diagnosis of preterm labour as well as accurate prediction of PTB is notoriously difficult. Preterm birth is initiated by multiple mechanisms including infection or inflammation which is the only pathological process for which a firm causal link with PTB has been established. Intrauterine infection evokes an immune response that involves the release of cytokines and chemokines, prostaglandins and matrix-degrading enzymes. These substances trigger uterine contractions, membrane rupture and cervical ripening. Most intra-uterine infections are chronic and subclinical in nature and consequently hard to diagnose before labour or rupture of the membranes. The best studied site of infection is amniotic fluid, but this requires an invasive procedure. A non-invasive approach seems to be more relevant to clinical practice. However, few studies have investigated the maternal inflammatory response during preterm labour. Therefore, the overall objective of this study was to determine several inflammatory markers in maternal serum from pregnant women in labour (either term or preterm) vs. non-labouring controls. We completed a nested case control study in which singleton pregnancies were recruited at Ghent University Hospital and divided into groups according to gestational age and labour status. Multiple proteins were evaluated in maternal serum using enzyme-linked or multiplex bead immunoassays including soluble triggering receptor expressed on myeloid cells-1 (sTREM-1), matrix metalloproteinases (MMP)-9 and MMP-3, tissue inhibitor of metalloproteinases (TIMP)-1, TIMP-2, TIMP-3 and TIMP-4 and a panel of 30 cytokines, chemokines and growth factors.

Quantifying circulating hypoxia-induced RNA transcripts in maternal blood to determine in utero fetal hypoxic status

BACKGROUND

Hypoxia in utero can lead to stillbirth and severe perinatal injury. While current prenatal tests can identify fetuses that are hypoxic, none can determine the severity of hypoxia/acidemia. We hypothesized a hypoxic/acidemic fetus would up-regulate and release hypoxia-induced mRNA from the fetoplacental unit into the maternal circulation, where they can be sampled and quantified. Furthermore, we hypothesized the abundance of hypoxia induced mRNA in the maternal circulation would correlate with severity of fetal hypoxia/acidemia in utero. We therefore examined whether abundance of hypoxia-induced mRNA in the maternal circulation correlates with the degree of fetal hypoxia in utero.

METHODS

We performed a prospective study of two cohorts: 1) longitudinal study of pregnant women undergoing an induction of labor (labor induces acute fetal hypoxia) and 2) pregnancies complicated by severe preterm growth restriction (chronic fetal hypoxia). For each cohort, we correlated hypoxia induced mRNA in the maternal blood with degree of fetal hypoxia during its final moments in utero, evidenced by umbilical artery pH or lactate levels obtained at birth. Gestational tissues and maternal bloods were sampled and mRNAs quantified by microarray and RT-PCR.

RESULTS

Hypoxia-induced mRNAs in maternal blood rose across labor, an event that induces acute fetal hypoxia. They exhibited a precipitous increase across the second stage of labor, a particularly hypoxic event. Importantly, a hypoxia gene score (sum of the relative expression of four hypoxia-induced genes) strongly correlated with fetal acidemia at birth. Hypoxia-induced mRNAs were also increased in the blood of women carrying severely growth restricted preterm fetuses, a condition of chronic fetal hypoxia. The hypoxia gene score correlated with the severity of ultrasound Doppler velocimetry abnormalities in fetal vessels. Importantly, the hypoxia gene score (derived from mRNA abundance in maternal blood) was significantly correlated with the degree of fetal acidemia at birth in this growth restriction cohort.

CONCLUSIONS

Abundance of mRNAs coding hypoxia-induced genes circulating in maternal blood strongly correlates with degree of fetal hypoxia/acidemia. Measuring hypoxia-induced mRNA in maternal blood may form the basis of a novel non-invasive test to clinically determine the degree of fetal hypoxia/acidemia while in utero.

Associations between maternal and infant morbidities and sRAGE within the first week of life in extremely preterm infants

Background

Soluble RAGE (sRAGE) has been associated with multiple inflammatory responses including maternal chorioamnionitis and preeclampsia. Analysis of umbilical cord blood levels have also indicated that sRAGE levels in the infant are affected by maternal inflammation. S100b is a ligand for RAGE and increases in circulating S100b levels are associated with poor neurological outcome in preterm infants. The objective of this study was to determine whether sRAGE or s100b levels in plasma samples from extremely preterm infants at the end of the first week of life were correlated with infant morbidities and whether sRAGE and s100b levels at this time point were still associated with maternal inflammation.

Methods

Plasma samples were collected from 130 preterm infants (≤28 weeks) at days of life 5, 6, or 7. sRAGE and s100b levels were measured by ELISA and data were analyzed by Pearson’s correlation or Generalized Estimating Equations.

Results

sRAGE was negatively correlated with development of sepsis (p=0.024), the FiO₂ requirement of the infant at the time of sampling (p=0.030), as well as maternal preeclampsia (p=0.046), and positively correlated with maternal chorioamnionitis (p=0.006). s100b levels were positively associated with maternal chorioamnionitis (p=0.039). No correlations were observed with other infant morbidities.

Conclusion

These data indicate that sRAGE could potentially be a biomarker of early severe inflammatory responses in the preterm infant. However, more studies are needed to confirm the present findings.