Hormonal changes accompanying cigarette smoke-induced preterm births in a mouse model

Association between secondhand smoke exposure and serum sex hormone concentrations among US female adults: a cross-sectional analysis using data from the National Health and Nutrition Examination Survey, 2013-2016

OBJECTIVE

To estimate the association between secondhand smoke (SHS) exposure and serum sex hormone concentrations in female adults (never smokers and former smokers).

DESIGN

Cross-sectional analysis.

SETTING

US National Health and Nutrition Examination Survey, 2013-2016.

OUTCOME MEASURES

Serum sex hormone measures included total testosterone (TT) and oestradiol (E2), sex hormone-binding globulin (SHBG), the ratio of TT and E2 and free androgen index (FAI). Isotope dilution-liquid chromatography tandem mass spectrometry was used to measure serum TT and E2. SHBG was measured using immunoassay. The ratio of TT and E2 and FAI were calculated. SHS exposure was defined as serum cotinine concentration of 0.05-10 ng/mL.

PARTICIPANTS

A total of 622 female participants aged ≥20 years were included in the analysis.

RESULTS

For never smokers, a doubling of serum cotinine concentration was associated with a 2.85% (95% CI 0.29% to 5.47%) increase in TT concentration and a 6.29% (95% CI 0.68% to 12.23%) increase in E2 in fully adjusted models. The never smokers in the highest quartile (Q4) of serum cotinine level exhibited a 10.30% (95% CI 0.78% to 20.72%) increase in TT concentration and a 27.75% (95% CI 5.17% to 55.17%) increase in E2 compared with those in the lowest quartile (Q1). For former smokers, SHBG was reduced by 4.36% (95% CI -8.47% to -0.07%, p for trend=0.049) when the serum cotinine level was doubled, and the SHBG of those in Q4 was reduced by 17.58% (95% CI -31.33% to -1.07%, p for trend=0.018) compared with those in Q1.

CONCLUSION

SHS was associated with serum sex hormone concentrations among female adults. In never smokers, SHS was associated with increased levels of TT and E2. In former smokers, SHS was associated with decreased SHBG levels.

Association between maternal cigarette smoking cessation and risk of preterm birth in Western New York

BACKGROUND

Although many studies suggested the benefit of smoking cessation among pregnant women in reducing the risk of preterm birth (PTB), the timing of the effect of the cessation remains inconclusive.

OBJECTIVES

To examine the association of trimester-specific smoking cessation behaviours with PTB risk.

METHODS

We included 199,453 live births in Western New York between 2004 and 2018. Based on self-reported cigarette smoking during preconception and in each trimester, we created six mutually exclusive groups: non-smokers, quitters in each trimester, those who smoked throughout pregnancy, and inconsistent smokers. Risk ratios (RRs) and 95% confidence intervals (CIs) were estimated using Poisson regression to examine the association between smoking cessation and PTB. Effect modification by illegal drug use, maternal age, race and ethnicity and pre-pregnancy body mass index (BMI) was investigated multiplicatively by ratio of relative risk and additively by relative excess risk due to interaction (RERI).

RESULTS

Overall, 6.7% of women had a PTB; 14.1% smoked throughout pregnancy and 3.4%, 1.8% and 0.8% reported quitting smoking during the first, second and third trimesters, respectively. Compared to non-smokers, third-trimester cessation (RR 1.20, 95% CI 1.01, 1.43) and smoking throughout pregnancy (RR 1.27, 95% CI 1.21, 1.33) were associated with a higher PTB risk, while quitting smoking during the first or second trimester, or inconsistent smoking was not associated with PTB. A positive additive interaction was identified for maternal age and late smoking cessation or smoking throughout pregnancy on PTB risk (RERI 0.17, 95% CI 0.00, 0.36), and a negative interaction was observed for pre-pregnancy BMI ≥30 kg/m2 (ratio of relative risk 0.70, 95% CI 0.63, 0.78; RERI -0.42, 95% CI -0.56, -0.30).

CONCLUSION

Compared to non-smokers, smoking throughout pregnancy and third-trimester smoking cessation are associated with an increased risk of PTB, while quitting before the third trimester may not increase PTB risk.

Genome-wide Interaction Study Implicates VGLL2 and Alcohol Exposure and PRL and Smoking in Orofacial Cleft Risk

Non-syndromic cleft lip with or without cleft palate (NSCL/P) is a common birth defect, affecting approximately 1 in 700 births. NSCL/P has complex etiology including several known genes and environmental factors; however, known genetic risk variants only account for a small fraction of the heritability of NSCL/P. It is commonly suggested that gene-by-environment (G×E) interactions may help explain some of the “missing” heritability of NSCL/P. We conducted a genome-wide G×E interaction study in cases and controls of European ancestry with three common maternal exposures during pregnancy: alcohol, smoking, and vitamin use using a two-stage design. After selecting 127 loci with suggestive 2df tests for gene and G x E effects, 40 loci showed significant G x E effects after correcting for multiple tests. Notable interactions included SNPs of 6q22 near VGLL2 with alcohol and 6p22.3 near PRL with smoking. These interactions could provide new insights into the etiology of CL/P and new opportunities to modify risk through behavioral changes.

Effect of 2,6-xylidine (DMA) on secretion of biomarkers for inflammation and neurodevelopment by the placenta

Cigarette smoke enhances placental inflammation and interferes with steroidogenesis. However, the chemicals in the smoke responsible for these biological activities are unclear. 2,6 xylidine (also called 2,6 Dimethylaniline, DMA) is a component of cigarette smoke that has carcinogenic properties but its effects on the placenta are unknown. Therefore, we hypothesized that DMA may interfere with placental steroidogenesis or enhance placental inflammation. Placental explant cultures were treated with 0-50,000 nM DMA and concentrations of progesterone (P₄), estradiol (E₂), testosterone (T), IL-1β, TNF-α, IL-6, sgp130, HO-1, IL-10, 8-Isoprostane (8-IsoP), and BDNF in the conditioned medium were quantified. Since many environmental toxins enhance the proinflammatory host response to infection, we also performed experiments on placental cultures co-stimulated with 10⁷ heat-killed E. coli. DMA alone significantly reduced P₄ and T secretion but enhanced E₂ secretion. The toxin also reduced placental secretion of IL-6, sgp130, and BDNF. For bacteria-stimulated cultures, DMA increased secretion of P₄ and T, and proinflammatory cytokines (IL-1β, TNF-α) but had mixed effects on anti-inflammatory markers, increasing some (sgp130, IL-10) and reducing others (HO-1). However, DMA enhanced 8-IsoP levels by bacteria-stimulated placental cultures, suggesting that it increases oxidative stress by the tissues. These studies suggest that DMA affects secretion of biomarkers by the placenta and may promote inflammation. Further studies are needed to determine if these observed changes occur in vivo and the extent to which DMA exposure increases the risk of adverse pregnancy outcomes associated with smoking in pregnancy.

In utero exposure to genistein decreased intranasal house dust mite-induced respiratory allergy in middle-aged male B6C3F1 offspring

Despite many hypothesized benefits of dietary isoflavone genistein (GEN) deriving from soy-based products, questions surrounding GEN's developmental effects are increasing. To understand if in utero GEN exposure modulated postnatal respiratory allergies in the middle age, we conducted a time course study in the B6C3F1 offspring (PND 240-330) using a common household allergen (house dust mites: HDM; 10 μg/mouse for PND 240 and 290, and 50 μg/mouse for PND 330, a middle age in mice) following intranasal instillation, a physiological route of allergen exposure. GEN was administered to dams by gavage from gestational day 14 to parturition at a physiologically relevant dose (20 mg/kg body weight). Female and male offspring were sensitized with HDM allergens beginning about one month prior to sacrifice followed by challenges with three weekly dosings of HDM extracts, and they were euthanized at day 3 following the final HDM exposure. In utero exposure to GEN decreased HDM allergen-induced respiratory allergy in male B6C3F1 offspring at PND 330 as reflected by decreases in airway hyperresponsiveness (e.g., Penh value), HDM-specific IgG₁ (a Th2 type Ab) and the activity of eosinophil peroxidase in the lung (an indication of eosinophil recruitment to the lungs). However, in utero exposure to GEN had minimal effects on HDM allergen-induced respiratory allergy in the middle-aged female offspring. Changes in serum total IgE, HDM-specific IgE, and lung histopathology scores in both male and female offspring were not biologically significant. Overall, in utero GEN exposure exerted a protective effect on respiratory allergy in the middle-aged male, but not female, B6C3F1 offspring following later-life HDM exposures.

Mouse models of preterm birth: suggested assessment and reporting guidelines

Preterm birth affects approximately 1 out of every 10 births in the United States, leading to high rates of mortality and long-term negative health consequences. To investigate the mechanisms leading to preterm birth so as to develop prevention strategies, researchers have developed numerous mouse models of preterm birth. However, the lack of standard definitions for preterm birth in mice limits our field's ability to compare models and make inferences about preterm birth in humans. In this review, we discuss numerous mouse preterm birth models, propose guidelines for experiments and reporting, and suggest markers that can be used to assess whether pups are premature or mature. We argue that adoption of these recommendations will enhance the utility of mice as models for preterm birth.

Smoking alters hydroxyprostaglandin dehydrogenase expression in fetal membranes

INTRODUCTION

The way in which tobacco smoking increases the risk of preterm labor remains uncertain. Altered prostaglandin metabolism is one potential mechanism.

METHODS

Proteins in fetal membrane samples (amniochoriodecidua) from 20 women were relatively quantified using Tandem Mass Tagging nano-liquid chromatography mass spectrometry.

RESULTS

Prostaglandin synthases and two enzymes involved in prostaglandin degradation, hydroxyprostaglandin dehydrogenase (HPGD) and CBR1, were detected by the mass spectrometer. The expression of HPGD was significantly lower in smokers relative to non-smokers (0.43 fold, p = 0.016). There was no effect of labor, inflammatory status or gestational age on the HPGD levels.

DISCUSSION

We describe for the first time an association between maternal smoking and HPGD expression. We propose that reduced expression of HPGD is one mechanism through which smoking may contribute to preterm labor. Lower levels of this enzyme, key to metabolising prostaglandins, may result in higher levels of prostaglandins and therefore precipitate labor prematurely.

Combined effects of AHR, CYP1A1, and XRCC1 genotypes and prenatal maternal smoking on infant birth size: Biomarker assessment in the Hokkaido Study

OBJECTIVES

We investigated the individual and combined effects of maternal polymorphisms encoding the aromatic hydrocarbon receptor (AHR; rs2066853), cytochrome P450 (CYP) 1A1 (rs1048963), and the X-ray-complementing gene 1 (XRCC1; rs1799782) and prenatal smoking in relation to infant birth size.

METHODS

Totally, 3263 participants (1998 non-smokers and 1265 smokers) were included in the study between 2003 and 2007. Two groups of mothers were distinguished by plasma cotinine levels by ELISA measured during the third trimester (cut-off=11.48ng/mL). We conducted data analysis using multiple linear regression models.

RESULTS

Infants whose mothers smoked and had AHR-GG, CYP1A1-AG/GG, and XRCC1-CT/TT genotypes weighed, -145g less than those born of mothers who did not smoke and had the AHR-GA/AA, CYP1A1-AA, and XRCC1-CC genotypes (95% CI: -241, -50).

CONCLUSIONS

We demonstrated that infants whose mothers smoked during pregnancy with the combination of AHR, CYP1A1, and XRCC1 polymorphisms had lower birth size.

Anti-atherosclerotic effects of serelaxin in apolipoprotein E-deficient mice

BACKGROUND AND AIMS

Serelaxin (SLX) is a recombinant form of human relaxin-2, a naturally occurring peptide that regulates maternal cardiovascular adaptations to pregnancy. It is unclear whether SLX has a therapeutic effect on atherosclerosis. Therefore, we investigated direct vascular effects of SLX in a mouse model of atherosclerosis.

METHODS

6-8 week-old female apolipoprotein E-deficient mice were fed a high-fat, cholesterol-rich diet for 6 weeks and additionally received a continuous treatment with vehicle or SLX (0.05 or 0.1 μg/h), during the last 4 weeks, via subcutaneously implanted osmotic mini-pumps. Vascular oxidative stress, vasorelaxation and atherosclerotic plaque development were assessed.

RESULTS

Vascular oxidative stress was reduced in SLX-treated mice (vehicle: 322.67 RLU/s, SLX 0.05 μg/h: 119.76 RLU/s (p < 0.001 vs. vehicle), SLX 0.1 μg/h: 109.33 RLU/s (p < 0.001 vs. vehicle; p = 0.967 vs. 0.05 μg/h SLX)). Further SLX improved endothelium-dependent vasodilatation without influencing endothelium-independent vasorelaxation. Atherosclerotic plaque development was significantly reduced by SLX (vehicle: 0.38 ± 0.02 mm(2), 0.05 μg/h SLX: 0.32 ± 0.02 mm(2) (p = 0.047 vs. vehicle), 0.1 μg/h SLX: 0.29 ± 0.02 mm(2) (p = 0.002 vs. vehicle; p = 0.490 vs. 0.05 μg/h SLX)). Neither vascular macrophage, T-cell or neutrophil infiltration, nor collagen/vascular smooth muscle cell content differed between the groups. We observed a significant down-regulation of the angiotensin II type 1a receptor and a decrease in IL-6 and an increase in IL-10 plasma concentrations.

CONCLUSIONS

Our data demonstrates novel pleiotropic effects of SLX on vascular oxidative stress, endothelial dysfunction and atherosclerotic plaque burden. Therefore, SLX could serve as a new drug for the treatment of atherosclerosis-related diseases.

In Utero exposure to genistein enhanced intranasal house dust mite allergen-induced respiratory sensitization in young adult B6C3F1 mice

Despite many hypothesized benefits of dietary isoflavone genistein (GEN) deriving from soy-based products, questions surrounding GEN's developmental immunotoxic effects are increasing. To understand how in utero GEN exposure may modulate postnatal respiratory sensitization, we conducted a time course study using a common household allergen (house dust mites: HDM; 10μg/mouse) following intranasal instillation, a physiological route of allergen exposure. GEN was administered to dams by gavage from gestational day 14 to parturition at a physiologically relevant dose (20mg/kg bw). Female and male offspring were sensitized with HDM allergens beginning about one month prior to sacrifice followed by challenges with three weekly doses of HDM extracts, and they were euthanized at day 3 following the final HDM exposure at four different time points (postnatal day (PND) 80, 120, 160, and 200). In utero GEN combined with postnatal HDM exposures (GEN+HDM) increased total IgE production in both young female and male B6C3F1 offspring (e.g., PND 80 in females and PND 120 in males). Increased antigen-specific IgG1, IgG2a and IgG2b levels were also observed at various time points in both female and male offspring. In addition, increases in macrophage number in bronchoalveolar lavage fluid of both female and male GEN+HDM offspring at PND 80 and PND 120, respectively, were observed when compared to the vehicle group. For T cells, an increase over the vehicle in female GEN+HDM offspring was observed at PND 80. Due to similar patterns of increases, it seems likely that GEN+HDM-induced increases in total IgE and macrophages are related. Overall, in utero GEN plus later-life HDM exposures exert increases in total IgE and HDM-specific IgG production as well as macrophage recruitments to the lung in young adult mice.

Relaxin deficiency results in increased expression of angiogenesis- and remodelling-related genes in the uterus of early pregnant mice but does not affect endometrial angiogenesis prior to implantation

BACKGROUND

Extensive uterine adaptations, including angiogenesis, occur prior to implantation in early pregnancy and are potentially regulated by the peptide hormone relaxin. This was investigated in two studies. First, we took a microarray approach using human endometrial stromal (HES) cells treated with relaxin in vitro to screen for target genes. Then we aimed to investigate whether or not relaxin deficiency in mice affected uterine expression of representative genes associated with angiogenesis and uterine remodeling, and also blood vessel proliferation in the pre-implantation mouse endometrium.

METHODS

Normal HES cells were isolated and treated with recombinant human relaxin (10 ng/ml) for 24 h before microarray analysis. Reverse transcriptase PCR was used to analyze gene expression of relaxin and its receptor (Rxfp1) in ovaries and uteri; quantitative PCR was used to analyze steroid receptor, angiogenesis and extracellular matrix remodeling genes in the uteri of wild type (Rln+/+) and Rln-/- mice on days 1-4 of pregnancy. Immunohistochemistry localized endometrial endothelial cell proliferation and mass spectrometry measured steroid hormones in the plasma.

RESULTS

Microarray analysis identified 63 well-characterized genes that were differentially regulated in HES cells after relaxin treatment. Expression of some of these genes was increased in the uterus of Rln+/+ mice by day 4 of pregnancy. There was significantly higher vascular endothelial growth factor A (VegfA), estrogen receptor 1 (Esr1), progesterone receptor (Pgr), Rxfp1, egl-9 family hypoxia-inducible factor 1 (Egln1), hypoxia inducible factor 1 alpha (Hif1α), matrix metalloproteinase 14 (Mmp14) and ankryn repeat domain 37 (Ankrd37) in Rln-/- compared to Rln+/+ mice on day 1. Progesterone receptor expression and plasma progesterone levels were higher in Rln-/- mice compared to Rln+/+ mice. However, endometrial angiogenesis was not advanced as pre-implantation endothelial cell proliferation did not differ between genotypes.

CONCLUSIONS

Relaxin treatment modulates expression of a variety of angiogenesis-related genes in HES cells. However, despite accelerated uterine gene expression of steroid receptor, progesterone and angiogenesis and extracellular matrix remodeling genes in Rln-/- mice, there was no impact on angiogenesis. We conclude that although relaxin deficiency results in phenotypic changes in the pre-implantation uterus, endogenous relaxin does not play a major role in pre-implantation angiogenesis in the mouse uterus.

Smoking and Preterm Birth

Premature birth is a significant global problem and the leading cause of newborn deaths. Tobacco smoking has been associated with premature birth for over 50 years. The mechanisms through which smoking exerts its effects on pregnancy outcomes remain unclear. In this review, we discuss rates of prematurity and smoking in pregnancy, the evidence of a causal relationship between tobacco and preterm birth, and proposed biochemical pathways through which the interaction is mediated. The suggested mechanisms include nicotine-induced vasoconstriction, carbon monoxide-induced fetal hypoxia, cadmium disruption of calcium signaling, altered steroid hormone production, disruption of prostaglandin synthesis, and changed responses to oxytocin. The relative importance of each of these pathways is yet to be ascertained. Further research is necessary to explore the mechanisms through which smoking exerts its effect on gestational length and the process of parturition. Moreover, the risks of nicotine replacement in pregnancy should be investigated further.

Genistein modulation of streptozotocin diabetes in male B6C3F1 mice can be induced by diet

Diet and phytoestrogens affect the development and progression of diabetes. The objective of the present study was to determine if oral exposure to phytoestrogen genistein (GE) by gavage changed blood glucose levels (BGL) through immunomodulation in streptozotocin (STZ)-induced diabetic male B6C3F1 mice fed with three different diets. These three diets were: NTP-2000 diet (NTP), soy- and alfalfa-free 5K96 diet (SOF) and high fat diet (HFD) with 60% of kcal from fat, primarily rendered fat of swine. The dosing regimen for STZ consisted of three 100mg/kg doses (i.p.): the first dose was administered at approximately 2weeks following the initiation of daily GE (20mg/kg) gavage, and the second dose was on day 19 following the first dose, and the third dose was on day 57 following the first dose. In mice on the NTP diet, GE treatment decreased BGL with statistical significances observed on days 33 and 82 following the first STZ injection. In mice fed the HFD diet, GE treatment produced a significant decrease and a significant increase in BGL on days 15 and 89 following the first STZ injection, respectively. In mice fed the SOF diet, GE treatment had no significant effects on BGL. Although GE treatment affected phenotypic distributions of both splenocytes (T cells, B cells, natural killer cells and neutrophils) and thymocytes (CD4/CD8 and CD44/CD25), and their mitochondrial transmembrane potential and generation of reactive oxygen species, indicators of cell death (possibly apoptosis), GE modulation of neutrophils was more consistent with its diabetogenic or anti-diabetic potentials. The differential effects of GE on BGL in male B6C3F1 mice fed with three different diets with varied phytoestrogen contents suggest that the estrogenic properties of this compound may contribute to its modulation of diabetes.

Reduced levels of maternal progesterone during pregnancy increase the risk for allergic airway diseases in females only

Observational as well as experimental studies support that prenatal challenges seemed to be associated with an increased risk for allergic airway diseases in the offspring. However, insights into biomarkers involved in mediating this risk are largely elusive. We here aimed to test the association between endogenous and exogenous factors documented in pregnant women, including psychosocial, endocrine, and life style parameters, and the risk for allergic airway diseases in the children later in life. We further pursued to functionally test identified factors in a mouse model of an allergic airway response. In a prospectively designed pregnancy cohort (n = 409 families), women were recruited between the 4th and 12th week of pregnancy. To investigate an association between exposures during pregnancy and the incidence of allergic airway disease in children between 3 and 5 years of age, multiple logistic regression analyses were applied. Further, in prenatally stressed adult offspring of BALB/c-mated BALB/c female mice, asthma was experimentally induced by ovalbumin (OVA) sensitization. In addition to the prenatal stress challenge, some pregnant females were treated with the progesterone derivative dihydrodydrogesterone (DHD). In humans, we observed that high levels of maternal progesterone in early human pregnancies were associated with a decreased risk for an allergic airway disease (asthma or allergic rhinitis) in daughters (adjusted OR 0.92; 95% confidence interval [CI] 0.84 to 1.00) but not sons (aOR 1.02, 95% CI 0.94-1.10). In mice, prenatal DHD supplementation of stress-challenged dams attenuated prenatal stress-induced airway hyperresponsiveness exclusively in female offspring. Reduced levels of maternal progesterone during pregnancy-which can result from high stress perception-increase the risk for allergic airway diseases in females but not in males. Key messages: Lower maternal progesterone during pregnancy increases the risk for allergic airway disease only in female offspring. Prenatal progesterone supplementation ameliorates airway hyperreactivity in prenatally stressed murine offspring.

Prenatal cigarette smoke exposure causes hyperactivity and aggressive behavior: role of altered catecholamines and BDNF

Smoking during pregnancy is associated with a variety of untoward effects on the offspring. However, recent epidemiological studies have brought into question whether the association between neurobehavioral deficits and maternal smoking is causal. We utilized an animal model of maternal smoking to determine the effects of prenatal cigarette smoke (CS) exposure on neurobehavioral development. Pregnant mice were exposed to either filtered air or mainstream CS from gestation day (GD) 4 to parturition for 4h/d and 5d/wk, with each exposure producing maternal plasma concentration of cotinine equivalent to smoking <1 pack of cigarettes per day (25ng/ml plasma cotinine level). Pups were weaned at postnatal day (PND) 21 and behavior was assessed at 4weeks of age and again at 4-6months of age. Male, but not female, offspring of CS-exposed dams demonstrated a significant increase in locomotor activity during adolescence and adulthood that was ameliorated by methylphenidate treatment. Additionally, male offspring exhibited increased aggression, as evidenced by decreased latency to attack and number of attacks in a resident-intruder task. These behavioral abnormalities were accompanied by a significant decrease in striatal and cortical dopamine and serotonin and a significant reduction in brain-derived neurotrophic factor (BDNF) mRNA and protein. Taken in concert, these data demonstrate that prenatal exposure to CS produces behavioral alterations in mice that are similar to those observed in epidemiological studies linking maternal smoking to neurodevelopmental disorders. Further, these data also suggest a role for monaminergic and BDNF alterations in these effects.

Relaxin regulates hyaluronan synthesis and aquaporins in the cervix of late pregnant mice

Cervical ripening is associated with loss of structural integrity and tensile strength, thus enabling the cervix to dilate at term. It is characterized by changes in glycosaminoglycan composition, increased water content, and a progressive reorganization of the collagen network. The peptide hormone relaxin via interaction with its receptor, relaxin family peptide receptor 1 (RXFP1), promotes tissue hydration and increases cervical hyaluronan (HA) concentrations, but the mechanisms that regulate these effects are not known. This study in relaxin mutant (Rln(-/-)) mice tested the hypothesis that relaxin regulates HA synthase and aquaporin (AQP) expression in the cervix. We also assessed expression of the RXFP1 protein by immunohistochemistry. Pregnant Rln(-/-) mice had lower Has2 and Aqp3 expression on d 18.5 of pregnancy and decreased cervical HA compared with wild-type Rln(+/+) mice. Chronic infusion of relaxin for 4 or 6 d in pregnant Rln(-/-) mice reversed these phenotypes and increased Has2 and Aqp3 compared with placebo controls. Relaxin-treated mice also had lower Has1 and Aqp5. Changes in gene expression were paralleled by increases in cervical HA and variations in AQP3 and AQP5 protein localization in epithelial cells of Rln(-/-) cervices. Our findings demonstrate that relaxin alters AQP expression in the cervix and initiates changes in glycosaminoglycan composition through increased HA synthesis. These effects are likely mediated through RXFP1 localized to subepithelial stromal cells and epithelial cells. We suggest these actions of relaxin collectively promote water recruitment into the extracellular matrix to loosen the dense collagen fiber network.

Secondhand tobacco smoke exposure is associated with prolactin but not thyroid stimulating hormone among nonsmoking women seeking in vitro fertilization

Prolactin (PRL) and thyroid stimulating hormone (TSH) serve important roles in the reproductive and other systems. Active smoking is associated with changes in PRL and TSH secretion, but the relationship between secondhand tobacco smoke (STS) exposure and these hormones is unclear. We measured PRL and TSH in serum as well as cotinine in follicular fluid (to estimate STS exposure) among 314 nonsmoking women undergoing in vitro fertilization treatment. We observed a significant increase in PRL concentrations (p=0.03) among STS-exposed nonsmokers compared to unexposed nonsmokers. There was no significant difference in TSH concentration (p>0.4) among those exposed to STS compared to those who were unexposed. STS exposure is associated with an increase in circulating PRL but not TSH levels. Future studies are needed to confirm our results, identify biological mechanisms involved, and better understand the potential clinical and public health implications.

Sex-specific effect of first-trimester maternal progesterone on birthweight

STUDY QUESTION

Are maternal progesterone levels in early pregnancy associated with fetal birthweight?

SUMMARY ANSWER

Low levels of first-trimester maternal progesterone are significantly associated with a reduction in birthweight in girls, but not boys.

WHAT IS ALREADY KNOWN

Progesterone in the third trimester of pregnancy has previously been related to birthweight in humans.

STUDY DESIGN, SIZE, DURATION

Pregnant women between gestational weeks 4 and 12 were recruited by 99 obstetricians in private practice and enrolled in a prospective cohort study. A follow-up took place at birth. Women younger than 18 years, who had undergone fertility treatments or were diagnosed with infectious diseases, were excluded from the study. A subgroup of 906 participants in whom progesterone had been measured was then selected retrospectively based on the following criteria: no miscarriages, elective abortions or pregnancy complications, infections or multiple births. Data from the follow-up were available for 623 women, who were included in the analyses.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study was coordinated at the Charité University Medicine in Berlin, Germany. Anthropometric, medical and psychosocial information were collected and serum progesterone and estradiol levels were measured in women during the first trimester of pregnancy, followed by the documentation of the pregnancy outcome at birth. Univariable and multivariable regression analyses were performed to identify maternal markers, among them progesterone, affecting birthweight and to determine environmental and maternal factors that are associated with maternal progesterone levels during pregnancy.

MAIN RESULTS AND THE ROLE OF CHANCE

In the multivariable regression model, each increase in maternal progesterone by 1 ng/ml during the first trimester increased girls' birthweight by 10.17 g (95% CI: 2.03-18.31 g). If the mother carried a boy, maternal smoking and perceived worries during early pregnancy predicted a reduced birthweight, irrespective of progesterone levels. Maternal body mass index over 25 and maternal age <21 years significantly correlated with the reduced levels of progesterone. Correlations between environmental challenges and maternal progesterone did not reach levels of significance. Since the analyses were exploratory, the likelihood that results may be due to chance is increased.

LIMITATIONS, REASONS FOR CAUTION

Due to the exploratory nature of the analyses, results need to be independently confirmed in a larger sample. Furthermore, our findings pertain to pregnant women without pregnancy complications or fertility treatments.

WIDER IMPLICATIONS OF THE FINDINGS

Maternal progesterone during early pregnancy is an indicator of subsequent fetal development in female children. Future studies should confirm this relationship and determine whether maternal progesterone is a useful tool in predicting pregnancies at risk resulting in the birth of a girl with low birthweight. Detailed identification of environmental factors modulating maternal progesterone levels should be addressed in future studies.

STUDY FUNDING/POTENTIAL COMPETING INTERESTS

Financial support was provided by the Alexander von Humboldt Foundation, Excellence Initiative of the Hamburg Foundation for Research and the Association for Prevention and Information for Allergy and Asthma (Pina e.V.). The authors have no conflict of interest.

Cigarette smoking and brain regulation of energy homeostasis

Cigarette smoking is an addictive behavior, and is the primary cause of cardiovascular and pulmonary disease, and cancer (among other diseases). Cigarette smoke contains thousands of components that may affect caloric intake and energy expenditure, although nicotine is the major addictive substance present, and has the best described actions. Nicotine exposure from cigarette smoke can change brain feeding regulation to reduce appetite via both energy homeostatic and reward mechanisms, causing a negative energy state which is characterized by reduced energy intake and increased energy expenditure that are linked to low body weight. These findings have led to the public perception that smoking is associated with weight loss. However, its effects at reducing abdominal fat mass (a predisposing factor for glucose intolerance and insulin resistance) are marginal, and its promotion of lean body mass loss in animal studies suggests a limited potential for treatment in obesity. Smoking during pregnancy puts pressure on the mother's metabolic system and is a significant contributor to adverse pregnancy outcomes. Smoking is a predictor of future risk for respiratory dysfunction, social behavioral problems, cardiovascular disease, obesity, and type-2 diabetes. Catch-up growth is normally observed in children exposed to intrauterine smoke, which has been linked to subsequent childhood obesity. Nicotine can have a profound impact on the developing fetal brain, via its ability to rapidly and fully pass the placenta. In animal studies this has been linked with abnormal hypothalamic gene expression of appetite regulators such as downregulation of NPY and POMC in the arcuate nucleus of the hypothalamus. Maternal smoking or nicotine replacement leads to unhealthy eating habits (such as junk food addiction) and other behavioral disorders in the offspring.

Maternal allergy acts synergistically with cigarette smoke exposure during pregnancy to induce hepatic fibrosis in adult male offspring

Maternal environmental exposures during pregnancy are known to affect disease onset in adult offspring. For example, maternal asthma exacerbations during pregnancy can worsen adult asthma in the offspring. Cigarette smoking during pregnancy is associated with future onset of cardiovascular disease, obesity and diabetes. However, little is known about the effect of maternal environmental exposures on offspring susceptibility to liver disease. This pilot study examined the long-term effect of maternal allergen challenge and/or cigarette smoking during pregnancy on hepatic inflammation and fibrosis in adult mouse offspring. Ovalbumin (OVA) or phosphate-buffered saline (PBS)-sensitized/challenged CD-1 dams were exposed to mainstream cigarette smoke (MCS) or filtered air from gestational day 4 until parturition. Eight weeks postnatally, offspring were sacrificed for comparison of hepatic histology and mRNA expression. Adult male offspring of OVA-sensitized/challenged dams exposed to MCS (OSM) displayed significantly increased liver fibrosis (9.2% collagen content vs. <4% for all other treatment groups). These mice also had 1.8-fold greater collagen 1A1 mRNA levels. From the results here, we concluded that maternal allergen challenge in combination with cigarette smoke exposure during pregnancy may be an important risk factor for liver disease in adult male offspring.

Highway to health; or How prenatal factors determine disease risks in the later life of the offspring

Fetal development is largely dependent on the mother. However, pregnancy maintenance and consequently fetal development are highly vulnerable and sensitive to disruption, triggered by, for example, prenatal stress challenge. Such prenatal stress challenge modulates the maternal endocrine and immune responses during pregnancy e.g. by decreasing levels of progesterone. Prenatal stress also has negative repercussions for the child's health later in life. It has been reported that prenatal stress increases the risk of the child to develop chronic immune diseases such as allergies and asthma. We therefore propose that prenatal stress challenge - associated with a decrease in maternal progesterone - impairs fetal immune development (immune ontogeny). Such impaired immune ontogeny carries over into postnatal life, rendering the child more prone to developing chronic immune diseases. This purported association urgently requires a fresh evaluation in order to identify biomarkers and cascades of events. In the present review, we outline candidate biomarkers involved in fetal immune ontogeny, which may be targets of prenatal stress challenge and subsequently determine offspring disease risk. Identification of these stress-sensitive biomarkers may allow detection of pregnant women at risk to deliver chronic immune disease-prone offspring. The creation of therapeutic interventions designed to prevent negative consequences of prenatal stress would then be within reach.

Measurement of sex steroids in murine blood and reproductive tissues by liquid chromatography-tandem mass spectrometry

Accurate measurement of sex steroids is essential to evaluate mouse models for human reproductive development and disorders. The recent advent of liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays that match the sensitivity of steroid immunoassay could overcome problems arising from the limited specificity of steroid immunoassay. In this current study we validate a LC-MS/MS assay for the measurement of key sex steroids from murine serum and reproductive tissues. The assay gave excellent dilutional linearity (r(2)> or =0.98) and reproducibility (CV< or =10% of replicate samples) in serum and reproductive tissues with sensitive quantitation limits; testosterone (T; 2pg), dihydrotestosterone (DHT; 10pg), 5alpha-androstane-3alpha,17beta-diol (3alphaDiol; 40pg), 5alpha-androstane-3beta,17beta-diol (3betaDiol; 40pg), estradiol (E2; 0.5pg) and estrone (E1; 0.3pg). Using 0.1mL sample, T was the only consistently detectable steroid (detection limit 20pg/ml) in both male and female mouse serum. In the testis, T and DHT were quantifiable as were both diols at relatively high levels. Prostatic T levels were low and DHT was determined to be the most abundant androgen in this tissue. Uterine and ovarian levels of E2, E1 and T were measurable, with levels varying according to estrous cycle stage. Hence, we demonstrate that this LC-MS/MS method has the sensitivity, specificity and multi-analyte capability to offer accurate steroid profiling in mouse serum and reproductive tissues.

Early life insult from cigarette smoke may be predictive of chronic diseases later in life

Evidence is rapidly accumulating that links cigarette smoke (CS) exposure in utero with the development of a variety of disease pathologies in the older offspring including, type 2 diabetes, obesity, certain childhood cancers and respiratory disorders. The role that the fetal environment plays in these late-onset outcomes and the underlying cellular/molecular mechanisms by which these CS-induced effects may occur are currently unknown. Although we are becoming more aware of the fact that prenatal insult can underlie childhood/adult diseases, critical knowledge gaps still exist including gene-environment interactions, and how a CS-induced imbalance in immune dynamics (i.e. TH1/TH2) might affect asthma development and/or exacerbation later in life. In this mini-review we introduce the concept of sexual dimorphism in CS-induced late-onset disease outcomes, as well as explore the mechanisms by which CS exposure in utero can lead to cardiovascular, cancer and respiratory abnormalities in the exposed offspring. By addressing such questions using animal models, appropriate intervention strategies can be developed that will help to protect children's health and their long-term quality of life.

The role of parity status on cigarette smoke-induced modulation of anti-tumor immune mechanisms

Epidemiologic studies indicate that women who smoke cigarettes are more likely to experience adverse reproductive and immunological health effects. Despite these facts, 20-30% of American women still smoke during their reproductive years. As little is known of the relationship between smoking and the immune response during pregnancy, an investigation was conducted using parous and non-parous (virgin) B6C3F1 mice to investigate what role (if any) parity status had on cigarette smoke (CS) induced effects on immune functions important in surveillance against developing tumors. Pregnant mice were exposed to CS for 5 d/wk ( 4 hr/d) from gestational day 4 to parturition; virgin mice were exposed for an equivalent amount of time. Smoke- and parity-associated alterations in pulmonary histology and lung inflammation, along with tumor cell host resistance, and cytotoxic T-lymphocyte (CTL) activity were examined either 24- 48 hr or 5 wk post-exposure/parturition; in the parous mice, gestational parameters were also evaluated. Exposure to CS significantly increased tumor susceptibility in virgin mice first injected with EL4 lymphoma cells at the 5 wk post-exposure timepoint; tumor incidence began to increase in smoke-exposed virgin mice as early as 24- 48 hr post-exposure. Pregnancy itself increased tumor incidence in mice injected with EL4 cells 24- 48 hr after birth, but this effect then dissipated over 5 wk to levels seen in virgin mice. When EL4 injections were first performed at either timepoint in CS-exposed parous mice, the tumor incidence was not significantly different from that in the air-exposed parity-matched controls. CTL activity in CS-exposed parous mice was significantly increased from both nulliparous groups as well as from the parous air control mice examined 5 wk post-exposure. Results suggest that exposure to CS throughout gestation could act in combination with pregnancy-associated changes to up-regulate immune responses, potentially compromising fetal tolerance.

Effect of ER-beta gene disruption on estrogenic regulation of anxiety in female mice

It has been shown that long-term estrogen treatment in gonadectomized female mice increases anxiety levels. On the other hand, a recent study has reported that estrogen may down-regulate the levels of anxiety by acting through estrogen receptor (ER) beta. In the present study, we investigated the role of ER-beta in the regulation of anxiety levels in female mice after long-term estrogen treatment. Gonadectomized ER-beta knockout (betaERKO) female mice and their wild type (betaWT) littermates were implanted several different doses (experiment 1: 2.0 microg/day, experiment 2: 1.0, 0.4, 0.2 or 0.1 microg/day) of an estradiol benzoate (EB) or placebo pellet. Ten days after pellet implant, behavioral tests commenced to measure the anxiety levels (experiment 1: light-dark transition test (LDT), experiment 2: LDT, elevated plus maze test (EPM) and social investigation test (SIT)). We found that, at higher-doses, long-term treatment of EB had anxiogenic effects in both betaWT and betaERKO mice as indicated by a decrease of the time spent in the light side and the number of transitions between two sides during LDT. In contrast, several behavioral measurements indicated that the lower-doses treatment of EB might reduce the anxiety levels possibly through ER-beta. Particularly, the anxiolytic effects of EB in the SIT were more pronounced in betaWT mice than betaERKO mice. Together, the findings in the present study suggest that estrogen may have both anxiolytic and anxiogenic effects in female mice, and that ER-beta gene disruption did not affect anxiogenic regulation by estrogen in female mice, but partially affected anxiolytic regulation.

Intrauterine environments and breast cancer risk: meta-analysis and systematic review

Introduction

Various perinatal factors, including birth weight, birth order, maternal age, gestational age, twin status, and parental smoking, have been postulated to affect breast cancer risk in daughters by altering the hormonal environment of the developing fetal mammary glands. Despite ample biologic plausibility, epidemiologic studies to date have yielded conflicting results. We investigated the associations between perinatal factors and subsequent breast cancer risk through meta-analyses.

Methods

We reviewed breast cancer studies published from January 1966 to February 2007 that included data on birth weight, birth order, maternal age, gestational age, twin status, and maternal or paternal smoking. Meta-analyses using random effect models were employed to summarize the results.

Results

We found that heavier birth weights were associated with increased breast cancer risk, with studies involving five categories of birth weight identifying odds ratios (ORs) of 1.24 (95% confidence interval [CI] 1.04 to 1.48) for 4,000 g or more and 1.15 (95% CI 1.04 to 1.26) for 3,500 g to 3,999 g, relative to a birth weight of 2,500 to 2,599 g. These studies provided no support for a J-shaped relationship of birthweight to risk. Support for an association with birthweight was also derived from studies based on three birth weight categories (OR 1.15 [95% CI 1.01 to 1.31] for ≥4,000 g relative to <3,000 g) and two birth weight categories (OR 1.09 [95% CI 1.02 to 1.18] for ≥3,000 g relative to <3,000 g). Women born to older mothers and twins were also at some increased risk, but the results were heterogeneous across studies and publication years. Birth order, prematurity, and maternal smoking were unrelated to breast cancer risk.

Conclusion

Our findings provide some support for the hypothesis that in utero exposures reflective of higher endogenous hormone levels could affect risk for development of breast cancer in adulthood.