Fetal lung growth predicts the risk for early-life respiratory infections and childhood asthma

BACKGROUND

Early-life respiratory infections and asthma are major health burdens during childhood. Markers predicting an increased risk for early-life respiratory diseases are sparse. Here, we identified the predictive value of ultrasound-monitored fetal lung growth for the risk of early-life respiratory infections and asthma.

METHODS

Fetal lung size was serially assessed at standardized time points by transabdominal ultrasound in pregnant women participating in a pregnancy cohort. Correlations between fetal lung growth and respiratory infections in infancy or early-onset asthma at five years were examined. Machine-learning models relying on extreme gradient boosting regressor or classifier algorithms were developed to predict respiratory infection or asthma risk based on fetal lung growth. For model development and validation, study participants were randomly divided into a training and a testing group, respectively, by the employed algorithm.

RESULTS

Enhanced fetal lung growth throughout pregnancy predicted a lower early-life respiratory infection risk. Male sex was associated with a higher risk for respiratory infections in infancy. Fetal lung growth could also predict the risk of asthma at five years of age. We designed three machine-learning models to predict the risk and number of infections in infancy as well as the risk of early-onset asthma. The models' R2 values were 0.92, 0.90 and 0.93, respectively, underscoring a high accuracy and agreement between the actual and predicted values. Influential variables included known risk factors and novel predictors, such as ultrasound-monitored fetal lung growth.

CONCLUSION

Sonographic monitoring of fetal lung growth allows to predict the risk for early-life respiratory infections and asthma.

Towards decoding the space-time continuum of pregnancy

Pregnancy is likely nature's most elaborate model of dynamic adaptations occurring over a distinct period of time at specific sites of the maternal body. Spatially-resolved transcriptomic analyses now enable the comprehensive decoding of these dynamic adaptations during the early onset stages of mammalian pregnancies and throughout fetal development.

Increased late preterm birth risk and altered uterine blood flow upon exposure to heat stress

BACKGROUND

Climate change, in particular the exposure to heat, impacts on human health and can trigger diseases. Pregnant people are considered a vulnerable group given the physiological changes during pregnancy and the potentially long-lasting consequences for the offspring. Evidence published to date on higher risk of pregnancy complications upon heat stress exposure are from geographical areas with high ambient temperatures. Studies from geographic regions with temperate climates are sparse; however, these areas are critical since individuals may be less equipped to adapt to heat stress. This study addresses a significant gap in knowledge due to the temperature increase documented globally.

METHODS

Birth data of singleton pregnancies (n = 42,905) from a tertiary care centre in Hamburg, Germany, between 1999 and 2021 were retrospectively obtained and matched with climate data from the warmer season (March to September) provided by the adjacent federal meteorological station of the German National Meteorological Service to calculate the relative risk of heat-associated preterm birth. Heat events were defined by ascending temperature percentiles in combination with humidity over exposure periods of up to 5 days. Further, ultrasound data documented in a longitudinal prospective pregnancy cohort study (n = 612) since 2012 were used to identify pathophysiological causes of heat-induced preterm birth.

FINDINGS

Both extreme heat and prolonged periods of heat exposure increased the relative risk of preterm birth (RR: 1.59; 95% CI: 1.01-2.43; p = 0.045; RR: 1.20; 95% CI: 1.02-1.40; p = 0.025). We identified a critical period of heat exposure during gestational ages 34-37 weeks that resulted in increased risk of late preterm birth (RR: 1.67; 95% CI: 1.14-1.43; p = 0.009). Pregnancies with a female fetus were more prone to heat stress-associated preterm birth. We found heat exposure was associated with altered vascular resistance within the uterine artery.

INTERPRETATION

Heat stress caused by high ambient temperatures increases the risk of preterm birth in a geographical region with temperate climate. Prenatal routine care should be revised in such regions to provide active surveillance for women at risk.

FUNDING

Found in acknowledgements.

Climate change and pregnancy complications: From hormones to the immune response

Pregnant women are highly vulnerable to adverse environments. Accumulating evidence highlights that increasing temperatures associated with the ongoing climate change pose a threat to successful reproduction. Heat stress caused by an increased ambient temperature can result in adverse pregnancy outcomes, e.g., preterm birth, stillbirth and low fetal weight. The pathomechanisms through which heat stress interferes with pregnancy maintenance still remain vague, but emerging evidence underscores that the endocrine system is severely affected. It is well known that the endocrine system pivotally contributes to the physiological progression of pregnancy. We review – sometimes speculate - how heat stress can offset hormonal dysregulations and subsequently derail other systems which interact with hormones, such as the immune response. This may account for the heat-stress related threat to successful pregnancy progression, fetal development and long-term children’s health.

Disruption of Glucocorticoid Action on CD11c+ Dendritic Cells Favors the Generation of CD4+ Regulatory T Cells and Improves Fetal Development in Mice

A wealth of innate and adaptive immune cells and hormones are involved in mounting tolerance towards the fetus, a key aspect of successful reproduction. We could recently show that the specific cross talk between the pregnancy hormone progesterone and dendritic cells (DCs) is significantly engaged in the generation of CD4+ FoxP3+ regulatory T (Treg) cells while a disruption led to placental alterations and intra-uterine growth restriction. Apart from progesterone, also glucocorticoids affect immune cell functions. However, their functional relevance in the context of pregnancy still needs clarification. We developed a mouse line with a selective knockout of the glucocorticoid receptor (GR) on DCs, utilizing the cre/flox system. Reproductive outcome and maternal immune and endocrine adaptation of Balb/c-mated C57Bl/6 GRflox/floxCD11ccre/wt (mutant) females was assessed on gestation days (gd) 13.5 and 18.5. Balb/c-mated C57Bl/6 GRwt/wtCD11ccre/wt (wt) females served as controls. The number of implantation and fetal loss rate did not differ between groups. However, we identified a significant increase in fetal weight in fetuses from mutant dams. While the frequencies of CD11c+ cells remained largely similar, a decreased expression of co-stimulatory molecules was observed on DCs of mutant females on gd 13.5, along with higher frequencies of CD4+ and CD8+ Treg cells. Histomorphological and gene expression analysis revealed an increased placental volume and an improved functional placental capacity in mice lacking the GR on CD11c+ DCs. In summary, we here demonstrate that the disrupted communication between GCs and DCs favors a tolerant immune microenvironment and improves placental function and fetal development.

Inefficient Placental Virus Replication and Absence of Neonatal Cell-Specific Immunity Upon Sars-CoV-2 Infection During Pregnancy

Pregnant women have been carefully observed during the COVID-19 pandemic, as the pregnancy-specific immune adaptation is known to increase the risk for infections. Recent evidence indicates that even though most pregnant have a mild or asymptomatic course, a severe course of COVID-19 and a higher risk of progression to diseases have also been described, along with a heightened risk for pregnancy complications. Yet, vertical transmission of the virus is rare and the possibility of placental SARS-CoV-2 infection as a prerequisite for vertical transmission requires further studies. We here assessed the severity of COVID-19 and onset of neonatal infections in an observational study of women infected with SARS-CoV-2 during pregnancy. Our placental analyses showed a paucity of SARS-CoV-2 viral expression ex vivo in term placentae under acute infection. No viral placental expression was detectable in convalescent pregnant women. Inoculation of placental explants generated from placentas of non-infected women at birth with SARS-CoV-2 in vitro revealed inefficient SARS-CoV-2 replication in different types of placental tissues, which provides a rationale for the low ex vivo viral expression. We further detected specific SARS-CoV-2 T cell responses in pregnant women within a few days upon infection, which was undetectable in cord blood. Our present findings confirm that vertical transmission of SARS-CoV-2 is rare, likely due to the inefficient virus replication in placental tissues. Despite the predominantly benign course of infection in most mothers and negligible risk of vertical transmission, continuous vigilance on the consequences of COVID-19 during pregnancy is required, since the maternal immune activation in response to the SARS-CoV2 infection may have long-term consequences for children’s health.

Infant immunity against viral infections is advanced by the placenta-dependent vertical transfer of maternal antibodies

Neonatal passive immunity, derived from transplacental transfer of IgG antibodies from mother to fetus during pregnancy, can mitigate the risk for severe infections in the early postnatal period. Understanding the placenta as the gateway organ in this process, we aimed to evaluate the influence of specific factors modulating the transplacental IgG transfer rate (TPTR) in 141 mother/neonate pairs. We further evaluated the potential health advantage elicited by maternal IgG with regard to respiratory tract infections during infancy and early childhood. Data and biological samples collected within the prospective longitudinal pregnancy cohort study PRINCE (Prenatal Identification of Children's Health) were used for these analyses. We tested IgG antibody levels against seven pathogens (measles, mumps, rubella, tetanus, diphtheria, pertussis and influenza A) by ELISA and detected seropositivity in 72.6-100% of pregnant women and in 76.3-100% of their neonates, respectively. Cord blood IgG levels reached 137-160% of levels detected in maternal blood. Strikingly, assessment of TPTR for all seven antigens highlighted that TPTR strongly depends on individual placental function. Subsequent in-depth analysis of anti-influenza A IgG revealed a link between cord blood levels and uterine perfusion, measured by uterine artery pulsatility index. Moreover, higher cord blood anti-influenza A IgG levels were associated with a significantly reduced risk for respiratory tract infections during the first six months of life, indicating a high degree of cross-reactivity and possible pathogen-agnostic effects of anti-influenza A antibodies. Taken together, our data suggest that early life immunity is modulated by maternal IgG levels and individual placental features such as perfusion. Vaccination of pregnant women, i.e. against influenza, can increase neonatal antibody levels and hereby protect against early life respiratory infections. Consequently, specific guidelines should evolve in order to safeguard neonates born from pregnancies with poorer placental capacity for vertical transfer of protective antibodies.

Pathogenesis of preterm birth: bidirectional inflammation in mother and fetus

Preterm birth (PTB) complicates 5–18% of pregnancies globally and is a leading cause of maternal and fetal morbidity and mortality. Most PTB is spontaneous and idiopathic, with largely undefined causes. To increase understanding of PTB, much research in recent years has focused on using animal models to recapitulate the pathophysiology of PTB. Dysfunctions of maternal immune adaptations have been implicated in a range of pregnancy pathologies, including PTB. A wealth of evidence arising from mouse models as well as human studies is now available to support that PTB results from a breakdown in fetal-maternal tolerance, along with excessive, premature inflammation. In this review, we examine the current knowledge of the bidirectional communication between fetal and maternal systems and its role in the immunopathogenesis of PTB. These recent insights significantly advance our understanding of the pathogenesis of PTB, which is essential to ultimately designing more effective strategies for early prediction and subsequent prevention of PTB.

In-depth characterization of monocyte subsets during the course of healthy pregnancy

Pregnancy represents an immunological challenge for the maternal immune system. Pregnancy augments innate immune responses, and particularly monocytes contribute to maintaining the balance between pro- and anti-inflammatory immune responses required for the successful sequence of distinct immunological phases throughout pregnancy. Nonetheless, studies that focus on the heterogeneity of monocytes and analyze the alteration of monocyte subsets in a longitudinal approach throughout healthy pregnancies have remained scarce. In this study, we characterized the gradual phenotypic changes of monocyte subsets and the secretory potential of bulk monocytes in peripheral blood mononuclear cells of healthy pregnant women from a population-based prospective birth cohort study. Blood samples at predefined time points were analyzed using flow cytometry for in-depth characterization of monocyte subsets, which confirmed a shift from classical towards intermediate monocytes throughout pregnancy. Principal component analysis revealed characteristic phenotypic changes on monocyte subsets, especially on the intermediate monocyte subset, throughout pregnancy. Pregnancy-related hormones were measured in serum and β-human chorionic gonadotropin levels were significantly associated with expression of CD11b, CD116 and CCR2 on monocyte subsets. TLR4 and TLR7/8 stimulation of monocytes furthermore showed reduced polycytokine production towards the end of pregnancy. These data provide a comprehensive overview of phenotypic changes and secretory potential of monocytes in healthy pregnant women and establish a selective contribution of different monocyte subsets to healthy pregnancy. The results from this study therefore build a basis for future comparisons and evaluation of women with adverse pregnancy outcomes.

Vertically Transferred Immunity in Neonates: Mothers, Mechanisms and Mediators

Over the last years, an increasing number of outbreaks of vaccine-preventable infectious diseases has been reported. Besides elderly and immunocompromised individuals, newborns and small infants are most susceptible to infections, as their immune system is still immature. This vulnerability during infancy can be mitigated by the transplacental transfer of pathogen-specific antibodies and other mediators of immunity from mother to the fetus during pregnancy, followed postnatally by breast milk-derived immunity. Since this largely antibody-mediated passive immunity can prevent the newborn from infections, neonatal immunity depends strongly on the maternal concentration of respective specific antibodies during pregnancy. If titers are low or wane rapidly after birth, the protection transferred to the child may not be sufficient to prevent disease. Moreover, emerging concepts propose that mothers may transfer active immunity to the newborns via vertical transfer of pathogen-specific T cells. Overall, a promising strategy to augment and prolong neonatal immunity is to vaccinate the mother before or during pregnancy in order to boost maternal antibody concentrations or availability of specific T cells. Hence, a large number of pre-and postconceptional vaccine trials have been carried out to test and confirm this concept. We here highlight novel insights arising from recent research endeavors on the influence of prenatal maternal vaccination against pathogens that can pose a threat for newborns, such as measles, pertussis, rubella and influenza A. We delineate pathways involved in the transfer of specific maternal antibodies. We also discuss the consequences for children's health and long-term immunity resulting from an adjustment of prenatal vaccination regimes.

Steroids, Pregnancy and Fetal Development

Maternal glucocorticoids critically rise during pregnancy reaching up to a 20-fold increase of mid-pregnancy concentrations. Concurrently, another steroid hormone, progesterone, increases. Progesterone, which shows structural similarities to glucocorticoids, can bind the intracellular glucocorticoid receptor, although with lower affinity. Progesterone is essential for the establishment and continuation of pregnancy and it is generally acknowledged to promote maternal immune tolerance to fetal alloantigens through a wealth of immunomodulatory mechanisms. Despite the potent immunomodulatory capacity of glucocorticoids, little is known about their role during pregnancy. Here we aim to compare general aspects of glucocorticoids and progesterone during pregnancy, including shared common steroidogenic pathways, plasma transporters, regulatory pathways, expression of receptors, and mechanisms of action in immune cells. It was recently acknowledged that progesterone receptors are not ubiquitously expressed on immune cells and that pivotal features of progesterone induced- maternal immune adaptations to pregnancy are mediated via the glucocorticoid receptor, including e.g., T regulatory cells expansion. We hypothesize that a tight equilibrium between progesterone and glucocorticoids is critically required and recapitulate evidence supporting that their disequilibrium underlie pregnancy complications. Such a disequilibrium can occur, e.g., after maternal stress perception, which triggers the release of glucocorticoids and impair progesterone secretion, resulting in intrauterine inflammation. These endocrine misbalance might be interconnected, as increase in glucocorticoid synthesis, e.g., upon stress, may occur in detriment of progesterone steroidogenesis, by depleting the common precursor pregnenolone. Abundant literature supports that progesterone deficiency underlies pregnancy complications in which immune tolerance is challenged. In these settings, it is largely yet undefined if and how glucocorticoids are affected. However, although progesterone immunomodulation during pregnancy appear to be chiefly mediated glucocorticoid receptors, excess glucocorticoids cannot compensate by progesterone deficiency, indicating that additional und still undercover mechanisms are at play.

The mnemonic code of pregnancy: Comparative analyses of pregnancy success and complication risk in first and second human pregnancies

Obstetrical complications such as spontaneous abortion/miscarriage, fetal growth restriction, preeclampsia or preterm birth occur in approx. 15% of human pregnancies. Clinical experts often state that a previous uncomplicated pregnancy reduces the risk for complications in subsequent pregnancies. Vice versa, a prior pregnancy affected by obstetrical complications increases the risk for reoccurrence. However, published evidence directly underpinning these clinical statements is sparse. Considering that the maternal immune adaptation may be causally involved in determining the outcome of subsequent pregnancies, a comprehensive analysis of clinical data was long overdue. We here present a systematic analysis of clinical data using a PubMed-based approach to identify human studies with relevant information on birth weight and incidences of pregnancy complications in first and second pregnancies. From initially 18,592 publications, 37 studies were included in the quantitative data analysis. Women with a previous pregnancy affected by complications where a derailed immune response can be inferred have a 2.2-3.2-fold increased risk to be affected again in a subsequent pregnancy. Conversely, a normally progressing primary pregnancy reduced the risk for complications in a subsequent pregnancy by 35-65%. Moreover, an uncomplicated primary pregnancy was associated with a 4.2% increased birth weight in a following pregnancy without a difference in gestational age at delivery. In conclusion, the increased birth weight after previously uncomplicated pregnancies suggests that an immune memory is mounted during primary pregnancies. This immune memory may promote the successful outcome of subsequent pregnancies or - if missing or compromised - account for a risk perpetuation of pregnancy complications.

Progesterone modulates the T-cell response via glucocorticoid receptor-dependent pathways

PROBLEM

Steroid hormones such as progesterone and glucocorticoids rise during pregnancy and are accountable for the adaptation of the maternal immune system to pregnancy. How steroid hormones induce fetal tolerance is not fully understood. We hypothesized that steroid hormones selectively regulate the T-cell response by promoting T-cell death.

METHOD OF STUDY

We incubated murine spleen cells isolated from non-pregnant and pregnant mice with physiological concentrations of steroid hormones in vitro and analyzed T-cell subsets after 48 h of incubation. Results We found that progesterone and the synthetic glucocorticoid dexamethasone induce T-cell death. CD4⁺ regulatory T (T_reg ) cells were refractory toward progesterone-induced cell death, in contrast to conventional CD4⁺ T cells, which resulted in a preferential enrichment of CD4⁺ T_reg cells in culture. T cells isolated from pregnant mice at early and late gestation showed comparable sensitivity to steroid-induced cell death. The target receptor for progesterone in immune cells is controversially discussed. We provide here support of progesterone binding to the glucocorticoid receptor as only T cells lacking the glucocorticoid but not the progesterone receptor showed resistance against progesterone-induced death. Conclusions Our results indicate that high levels of progesterone during pregnancy can induce selective T-cell death by binding the glucocorticoid receptor. Although physiological hormone concentrations were used, due to different bioavailability of steroid hormones in vivo these results have to be validated in an in vivo model. This mechanism might ensure immunological tolerance at the feto-maternal interface at gestation.

Impaired Progesterone-Responsiveness of CD11c+ Dendritic Cells Affects the Generation of CD4+ Regulatory T Cells and Is Associated With Intrauterine Growth Restriction in Mice

Up to 10% of pregnancies in Western societies are affected by intrauterine growth restriction (IUGR). IUGR reduces short-term neonatal survival and impairs long-term health of the children. To date, the molecular mechanisms involved in the pathogenesis of IUGR are largely unknown, but the failure to mount an adequate endocrine and immune response during pregnancy has been proposed to facilitate the occurrence of IUGR. A cross talk between the pregnancy hormone progesterone and innate immune cell subsets such as dendritic cells (DCs) is vital to ensure adequate placentation and fetal growth. However, experimental strategies to pinpoint distinct immune cell subsets interacting with progesterone in vivo have long been limited. In the present study, we have overcome this limitation by generating a mouse line with a specific deletion of the progesterone receptor (PR) on CD11c⁺ DCs. We took advantage of the cre/loxP system and assessed reproductive outcome in Balb/c-mated C57Bl/6 PR^flox/floxCD11c^cre/wt females. Balb/c-mated C57Bl/6 PR^wt/wtCD11c^cre/wt females served as controls. In all dams, fetal growth and development, placental function and maternal immune and endocrine adaptation were evaluated at different gestational time points. We observed a significantly reduced fetal weight on gestational day 13.5 and 18.5 in PR^flox/floxCD11c^cre/wt females. While frequencies of uterine CD11c⁺ cells were similar in both groups, an increased frequency of co-stimulatory molecules was observed on DCs in PR^flox/floxCD11c^cre/wt mice, along with reduced frequencies of CD4⁺ FoxP3⁺ and CD8⁺ CD122⁺ regulatory T (Treg) cells. Placental histomorphology revealed a skew toward increased junctional zone at the expense of the labyrinth in implantations of PR^flox/floxCD11c^cre/wt females, accompanied by increased plasma progesterone concentrations. Our results support that DCs are highly responsive to progesterone, subsequently adapting to a tolerogenic phenotype. If such cross talk between progesterone and DCs is impaired, the generation of pregnancy-protective immune cells subsets such as CD4⁺ and CD8⁺ Treg cells is reduced, which is associated with poor placentation and IUGR in mice.

Innate immune responses to toll-like receptor stimulation are altered during the course of pregnancy

During pregnancy the maternal immune system has to develop tolerance towards the developing fetus. These changes in maternal immunity can result in increased severity of certain infections, but also in amelioration of autoimmune diseases. Pregnancy-related hormones have been suggested to play a central role in the adaptation of the maternal immune system, but their specific effects on innate immune function is not well understood. In a longitudinal study of pregnant women, we investigated innate immune cell function in response to toll-like receptors (TLR) 4 and 7 stimulation, two TLR pathways playing a critical role in early innate immune recognition of bacteria and viruses. IFNα production by TLR7-stimulated pDCs was decreased in early pregnancy, and increased towards the end of pregnancy. In contrast, pro-inflammatory TLR4-induced TNFα production by monocytes was increased during early pregnancy, but declined after the first trimester. Changes in cytokine production were associated with changes in pregnancy-related hormones and monocyte subpopulations over the course of pregnancy. These data demonstrating a significant association between pregnancy-related hormones and modulation of innate immune responses mediated by TLRs provide novel insights into the immunological adaptations occurring during pregnancy.

Prenatal stress perception and coping strategies: Insights from a longitudinal prospective pregnancy cohort

OBJECTIVE

Prenatal distress has been linked to pregnancy complications and poor offspring's health, despite the fact that longitudinal assessments of various stress dimensions are still lacking. Hence, we aimed to assess perceived stress over the course of pregnancy. Moreover, we examined whether social support and coping styles are linked to prenatal stress trajectories.

METHODS

Data from 543 women participating in the PRINCE (Prenatal Identification of Children Health) study, a prospective population-based cohort study, was used for the present analyses. Once per trimester the women completed questionnaires regarding different psychometric measures, including the Perceived Stress Scale (PSS). Linear mixed regression models were used to examine perceived stress development longitudinally and to relate social support and coping styles to stress trajectories during pregnancy.

RESULTS

A significant decrease of perceived stress was observed over the course of pregnancy. Stratifying the study sample according to parity, women delivering their first child had continuously lower perceived stress scores compared to women having already one or more children, and a significant decrease during pregnancy was exclusively observed in primiparous women. Both, positive coping strategies and higher perceived and received social support were independently associated with lower perceived stress, while evasive coping strategies were associated with higher levels of perceived stress.

CONCLUSION

Our study reveals stress perception trajectories during pregnancies in primi- and multiparous women. Our findings underscore the need for intervention strategies aiming to improve social support and positive coping strategies especially in multiparous women in order to reduce the risks for adverse pregnancy outcomes.

Pregnancy-Related Immune Adaptation Promotes the Emergence of Highly Virulent H1N1 Influenza Virus Strains in Allogenically Pregnant Mice

Pregnant women are at high risk for severe influenza disease outcomes, yet insights into the underlying mechanisms are limited. Here, we present models of H1N1 infection in syngenic and allogenic pregnant mice; infection in the latter mirrors the severe course of 2009 pandemic influenza in pregnant women. We found that the anti-viral immune response in the pregnant host was significantly restricted as compared to the non-pregnant host. This included a reduced type I interferon response as well as impaired migration of CD8⁺ T cells into the lung. The multi-faceted failure to mount an anti-viral response in allogenic pregnant mice resulted in a less stringent selective environment that promoted the emergence of 2009 H1N1 virus variants that specifically counteract type I interferon response and mediate increased viral pathogenicity. These insights underscore the importance of influenza vaccination compliance in pregnant women and may open novel therapeutic avenues.

CD74-Downregulation of Placental Macrophage-Trophoblastic Interactions in Preeclampsia

RATIONALE

We hypothesized that cluster of differentiation 74 (CD74) downregulation on placental macrophages, leading to altered macrophage-trophoblast interaction, is involved in preeclampsia.

OBJECTIVE

Preeclamptic pregnancies feature hypertension, proteinuria, and placental anomalies. Feto-placental macrophages regulate villous trophoblast differentiation during placental development. Disturbance of this well-balanced regulation can lead to pathological pregnancies.

METHODS AND RESULTS

We performed whole-genome expression analysis of placental tissue. CD74 was one of the most downregulated genes in placentas from preeclamptic women. By reverse transcriptase-polymerase chain reaction, we confirmed this finding in early-onset (<34 gestational week, n=26) and late-onset (≥34 gestational week, n=24) samples from preeclamptic women, compared with healthy pregnant controls (n=28). CD74 protein levels were analyzed by Western blot and flow cytometry. We identified placental macrophages to express CD74 by immunofluorescence, flow cytometry, and RT-PCR. CD74-positive macrophages were significantly reduced in preeclamptic placentas compared with controls. CD74-silenced macrophages showed that the adhesion molecules ALCAM, ICAM4, and Syndecan-2, as well as macrophage adhesion to trophoblasts were diminished. Naive and activated macrophages lacking CD74 showed a shift toward a proinflammatory signature with an increased secretion of tumor necrosis factor-α, chemokine (C-C motif) ligand 5, and monocyte chemotactic protein-1, when cocultured with trophoblasts compared with control macrophages. Trophoblasts stimulated by these factors express more CYP2J2, sFlt1, TNFα, and IL-8. CD74-knockout mice showed disturbed placental morphology, reduced junctional zone, smaller placentas, and impaired spiral artery remodeling with fetal growth restriction.

CONCLUSIONS

CD74 downregulation in placental macrophages is present in preeclampsia. CD74 downregulation leads to altered macrophage activation toward a proinflammatory signature and a disturbed crosstalk with trophoblasts.

Differential mouse-strain specific expression of Junctional Adhesion Molecule (JAM)-B in placental structures

The junctional adhesion molecule (JAM)-B, a member of the immunoglobulin superfamily, is involved in stabilization of interendothelial cell-cell contacts, formation of vascular tubes, homeostasis of stem cell niches and promotion of leukocyte adhesion and transmigration. In the human placenta, JAM-B protein is abundant and mRNA transcripts are enriched in first-trimester extravillous trophoblast in comparison to the villous trophoblast. We here aimed to elucidate the yet unexplored spatio-temporal expression of JAM-B in the mouse placenta. We investigated and semi-quantified JAM-B protein expression by immunohistochemistry in early post-implantation si tes and in mid- to late gestation placentae of various murine mating combinations. Surprisingly, the endothelium of the placental labyrinth was devoid of JAM-B expression. JAM-B was mainly present in spongiotrophoblast cells of the junctional zone, as well as in the fetal vessels of the chorionic plate, the umbilical cord and in maternal myometrial smooth muscle. We observed a strain-specific placental increase of JAM-B protein expression from mid- to late gestation in Balb/c-mated C57BL/6 females, which was absent in DBA/2J-mated Balb/c females. Due to the essential role of progesterone during gestation, we further assessed a possible modulation of JAM-B in mid-gestational placentae deficient in the progesterone receptor (Pgr(-/-)) and observed an increased expression of JAM-B in Pgr(-/-) placentae, compared to Pgr(+/+) tissue samples. We propose that JAM-B is an as yet underappreciated trophoblast lineage-specific protein, which is modulated via the progesterone receptor and shows unique strain-specific kinetics. Future work is needed to elucidate its possible contribution to placental processes necessary to ensuring its integrity, ultimately facilitating placental development and fetal growth.

Identification of suitable reference genes in the mouse placenta

INTRODUCTION

Quantitative real-time reverse transcription polymerase chain reaction (RT-qPCR) is a reliable tool to analyse gene expression profiles. The expression of housekeeping genes generally serves as a reference for mRNA amount, assuming that it remains stable under pathophysiological and experimental conditions. To date, an empirical validation of reference genes suitable for RT-qPCR-based studies in the mouse placenta is missing.

METHODS

We used NormFinder and BestKeeper statistical software to analyse the expression stability of candidate housekeeping genes quantified by RT-qPCR in mouse placentas.

RESULTS

Fifteen of 32 potential candidate housekeeping genes analysed on gestation day (gd) 16.5 in mouse placentas exhibited an optimal cycle threshold (Ct). Among them B2m, Polr2a, Ubc, and Ywhaz genes showed the highest expression stability in placentas from control, but also experimentally-challenged mice. These genes as well as the currently widely used housekeeping genes Hprt1, Actb, and Gapdh were selected for further quality assessments. We quantified the Ct values of these selected genes in placental samples obtained from wild-type or genetically engineered dams at different gds, or upon selected experimental interventions known to affect placental phenotype. Among all housekeeping genes analysed, Polr2a was the most stably expressed and its expression stability excelled in combination with Ubc.

DISCUSSION

Polr2a, especially in combination with Ubc, can be proposed as highly suitable endogenous reference for gene expression analysis in mouse-derived placental tissue. Moreover, the validation of both genes as a stable reference gene in human placenta-derived tissue strengthens the translational relevance of RT-qPCR findings using mouse placenta.

Progesterone and HMOX-1 promote fetal growth by CD8+ T cell modulation

Intrauterine growth restriction (IUGR) affects up to 10% of pregnancies in Western societies. IUGR is a strong predictor of reduced short-term neonatal survival and impairs long-term health in children. Placental insufficiency is often associated with IUGR; however, the molecular mechanisms involved in the pathogenesis of placental insufficiency and IUGR are largely unknown. Here, we developed a mouse model of fetal-growth restriction and placental insufficiency that is induced by a midgestational stress challenge. Compared with control animals, pregnant dams subjected to gestational stress exhibited reduced progesterone levels and placental heme oxygenase 1 (Hmox1) expression and increased methylation at distinct regions of the placental Hmox1 promoter. These stress-triggered changes were accompanied by an altered CD8+ T cell response, as evidenced by a reduction of tolerogenic CD8+CD122+ T cells and an increase of cytotoxic CD8+ T cells. Using progesterone receptor- or Hmox1-deficient mice, we identified progesterone as an upstream modulator of placental Hmox1 expression. Supplementation of progesterone or depletion of CD8+ T cells revealed that progesterone suppresses CD8+ T cell cytotoxicity, whereas the generation of CD8+CD122+ T cells is supported by Hmox1 and ameliorates fetal-growth restriction in Hmox1 deficiency. These observations in mice could promote the identification of pregnancies at risk for IUGR and the generation of clinical interventional strategies.

Advancing the detection of maternal haematopoietic microchimeric cells in fetal immune organs in mice by flow cytometry

Maternal microchimerism, which occurs naturally during gestation in hemochorial placental mammals upon transplacental migration of maternal cells into the fetus, is suggested to significantly influence the fetal immune system. In our previous publication, we explored the sensitivity of quantitative polymerase chain reaction and flow cytometry to detect cellular microchimerism. With that purpose, we created mixed cells suspensions in vitro containing reciprocal frequencies of wild type cells and cells positive for enhanced green fluorescent protein or CD45.1⁺, respectively. Here, we now introduce the H-2 complex, which defines the major histocompatibility complex in mice and is homologous to HLA in human, as an additional target to detect maternal microchimerism among fetal haploidentical cells. We envision that this advanced approach to detect maternal microchimeric cells by flow cytometry facilitates the pursuit of phenotypic, gene expression and functional analysis of microchimeric cells in future studies.

Sex, immunity and influenza

Sex-specific endocrine and immune responses are widely recognized to account for differential disease outcomes between females and males. Surprisingly, sex-specific risk assessments for influenza, a viral pathogen that affects human populations worldwide through seasonal epidemics and irregular occurring pandemics, are sparse and-if available-ambiguous. To date, this precludes proposing an unequivocal sex-dependent susceptibility to influenza. However, one undisputable observation recurrently confirmed during influenza seasons of the last decades is the significantly increased risk for pregnant women. This increased risk is likely attributable to the contradictory demands for the maternal immune system to adapt to pregnancy and to simultaneously mount an immune response to clear the influenza virus infection. Here, we review published evidence on the potential association between sex on influenza risk and propose that future epidemiologic studies should carefully dissect surveillance data for sex-specific effects. Moreover, we propose potential mechanisms involved in enhanced risk for severe influenza during pregnancy that could be studied to identify causal pathways.

[Prenatal sex-specific programming and chronic diseases or Finis Ab Orígine Pendet]

An increasing incidence of chronic immune diseases such as allergies, multiple sclerosis, and type 2 diabetes, as well as obesity and cardiovascular and psychiatric disorders has been reported over the last five decades. Since the human genome has not altered significantly over this period of time, gene-environment interactions are suspected to be responsible for these increased disease incidences. In this context, the prenatal period is believed to significantly contribute to altered disease susceptibilities, which could be associated with environmental factors to which pregnant women were exposed to. This observation has led to a concept entitled 'developmental origin of health and disease', a topic that is enjoying much attention in clinical and basic science research. The aim of these research endeavors is to postulate guidelines for primary disease prevention. Whilst the emerging insights from this field of research provide significant pieces of the puzzle, one area is still largely neglected: the clear identification of a sex-specific programming effect. Thus it is essential that such an approach becomes fully integrated in future research goals.

Diet-induced obesity may affect the uterine immune environment in early-mid pregnancy, reducing NK-cell activity and potentially compromising uterine vascularization

OBJECTIVES

To investigate the effect of obesity in early-mid pregnancy on crucial pregnancy hormones and the uterine immune environment.

BACKGROUND

Obesity impacts reproductive ability, adversely affecting conception and leading to complications in pregnancy. Obesity is often regarded as a stress state and an immune disease, both of which may contribute to pregnancy failure. We previously demonstrated that stress in early pregnancy greatly alters progesterone secretion. As progesterone is an immunomodulator, altered progesterone secretion may adversely modify the maternal immune system. In the current study, we test the hypothesis that obesity during pregnancy adversely alters the uterine immune environment.

METHODS

An obese mouse model was created by feeding C57/BL6 mice on a high-fat (HF)/sugar diet for 12 weeks before pregnancy. Control mice were fed on lower-fat/sugar chow. Mice were mated, and on day 7.5 of pregnancy plasma progesterone and prolactin were measured by immunoassay. Cells from the uterus-draining inguinal lymph nodes were collected for analysis of the uterine immune response by flow cytometry.

RESULTS

Diet-induced obesity increased the secretion of progesterone and altered a number of uterine natural killer (NK)- and T-cell responses. These included a marked reduction in the percentage of leucocyte-derived NK cells and reduced expression of interferon-γ (IFN-γ) in the NK cells compared with control mice.

CONCLUSIONS

Maternal obesity, induced by an HF diet, may lead to a reduction in the expression of IFN-γ in NK cells. NK-cell-derived IFN-γ is reported to be involved in supporting uterine spiral artery remodelling. Thus, obesity in early pregnancy may compromise vascularization by reducing the expression of IFN-γ-positive NK cells. Furthermore, the expression of uterine CD8(+) cells was reduced in the HF diet-fed mice, suggesting obesity may adversely alter the maternal immune adaptation that is essential for effective pregnancy.

Limitation of pro- and anti-inflammatory cytokine analysis to discriminate biological stress effects in patients suffering from chronic psychological distress

BACKGROUND

Research endeavors aiming to evaluate the effect of prolonged psychological distress on the immune system have been pursed over the past decades. Due to the complexity of the two systems involved, the mental and immune status, a large number of questions still remains to be addressed.

AIM

In the present study, we aimed to test if chronic distress is associated with pro- and anti-inflammatory cytokine levels in a well-defined study cohort.

METHODS

We recruited 42 inpatients suffering from post-traumatic embitterment disorder (PTED), a condition that has been demonstrated to cause intense and persistent psychological distress. Study participants completed established questionnaires to evaluate stress perception, depression and quality of life before and after psychotherapy, aiming to improve stress coping. Venous blood samples to detect serum levels of pro- and anti-inflammatory cytokines [interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor (TNF)-α, interferon (IFN)-γ] were obtained pre- and post-treatment.

RESULTS

The psychological assessments showed an increase of quality of life, a decrease of perceived stress and depressive symptoms, between the two groups. These findings are not associated with significant alterations of the cytokine levels before and after treatment.

CONCLUSIONS

In our study, the psychological treatment of inpatients suffering from chronic psychological distress does not result in changes in cytokine levels. Further research with a broader analysis of immune markers and enhanced detection methods may be required to unveil psycho-immunological association in PTED patients.

Regulation of pregnancy maintenance and fetal survival in mice by CD27(low) mature NK cells

Uterine natural killer (NK) cells are pivotal for successful mammalian reproduction. However, insights on functionally distinct subpopulations of uterine NK cells are largely elusive. Furthermore, translation of findings from murine into human pregnancy has been overshadowed by the limited number of mutual phenotypic NK cell markers. We here provide evidence that a subset of murine mature NK (mNK) cells present at the feto-maternal interface, identified as CD27(low)DX5(+)CD3(neg), is pivotal in maintaining pregnancy. This mNK subset has low cytotoxic capacity, produces higher amounts of interferon (IFN)-γ, and expresses functional homologs of human NK cell immunoglobulin-like receptors. We further show that bone marrow-derived CD27(low) mNK cells are selectively recruited to the uterus and ameliorate the rate of fetal loss when adoptively transferred into alymphoid RAG2(-/-)/γc(-/-) mice. Additionally, expression of CD27 is down-modulated on mNK cells upon migration to the uterus. Hence, we propose the existence of a regulatory mNK cell subset, which is licensed toward successful pregnancy maintenance at the fetomaternal interface in mice. As CD27(low) NK cells are also present in human decidua, the CD27(low) NK subset may provide a tool to foster translational research in reproduction, aiming to improve pregnancy outcome in humans.

Systemic inflammation, cellular influx and up-regulation of ovarian VCAM-1 expression in a mouse model of polycystic ovary syndrome (PCOS)

PCOS, a major cause of anovulatory sterility, is associated with obesity, insulin resistance and chronic inflammation. New evidence suggests that the immune system aggravates the clinical features of PCOS. Our aim was to study the immune, metabolic and endocrine features of a mouse model of PCOS elicited by androgenisation using dehydroepiandrosterone (DHEA). We observed a significant weight gain and insulin resistance in DHEA-androgenised mice, coupled with the formation of ovarian follicular cysts. DHEA up-regulated the expression of vascular cell adhesion molecule (VCAM)-1 and intercellular adhesion molecule (ICAM)-1 in the granulosa cell layer of the majority of cysts, and VCAM-1 expression in the theca cell layer of all follicles and cysts. The expression of these markers was low in control tissue. Peritoneal cells from PCOS-mice showed enhanced production of inflammatory cytokines, suggesting an association between chronic inflammation and PCOS. In addition, DHEA-androgenisation induced the activation of CD4(+) cells both in vivo and in vitro, and their expression of the respective ligands for VCAM-1 and ICAM-1, VLA-4 and LFA-1, as assessed in vitro. CD4(+) cells were present in androgenised ovaries, especially in the granulosa cell layer of cysts with high VCAM-1 expression. Herein, we present novel evidence that the immune system is activated systemically and locally in a mouse model for PCOS. We propose that VCAM-1 is involved in aggravating PCOS symptoms by promoting leukocyte recruitment to the ovaries and perpetuating local inflammation. These findings offer novel therapeutic opportunities for PCOS, such as blockage of VCAM-1 expression.

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.

Subclinical depressive symptoms affect responses to acute psychosocial stress in healthy premenopausal women

Subclinical depressive symptoms constitute a primary risk factor for major depression as well as for cardiovascular conditions, which may be mediated by endocrine or immune alterations. The aim of this study was to assess the association between the extent of subclinical depressive symptoms and neuroendocrine and immune cell responses to acute psychosocial stress in healthy females. In N = 33 healthy premenopausal women, state anxiety, plasma adrenocorticotropic hormone and serum cortisol, and interleukin-6 (IL-6) concentration responses to public speaking stress were assessed. Beck depression inventory (BDI) scores were entered as a covariate in the analyses. The IL-6 response was significantly associated with BDI scores (p < 0.05). Secondary analyses revealed that women with more subclinical depressive symptoms demonstrated a reduced stress-induced increase in circulating IL-6 level (p < 0.05). By contrast, stress-induced neuroendocrine activation was not associated with depressive symptoms. Hence, subclinical depressive symptoms were associated with IL-6 responses to stress in young, healthy women. Unexpectedly, there was a reduced increase of serum IL-6 level in response to stress. Effects of depressive symptoms on the IL-6 response to stress may differ between subclinical and major depression.

Natural Killer cells: keepers of pregnancy in the turnstile of the environment

During early pregnancy, an orchestrated endocrine-immunological scenario of maternal adaptation toward tolerance of the semiallogeneic fetus is required. Mechanisms preventing fetal loss by protecting the immune privilege of the gravid uterus, i.e. Galectin-1 or regulatory T cells, have recently been identified. Further, the presence of a unique population of Natural Killer (NK) cells, in humans identified by their CD56(+++)Galectin (Gal)-1(+)CD16(-) phenotype in the uterine lining (decidua), has been proposed to be a pivotal aspect of maternal adaptation to pregnancy. Decidual NK (dNK) cells comprise the largest population of immune cells during the first trimester in human decidua and control trophoblast invasion and vascular remodeling through their ability to secrete an array of angiogenesis-regulating molecules, chemokines and cytokines. A wealth of environmental factors, such as smoking, altered nutrition, pollution or stress has been proposed to peril not only pregnancy, but also fetal development. Further, published evidence supports that NK cells act as sentinel cells and environmental challenges can change their phenotype, e.g. via epigenetic pathways. We here review the effect of environmental factors, largely stress perception, on NK cells and its implication for pregnancy, fetal development and general health. As NK cells may not only be passive responders to the environment, but can also be 'educated and licensed', we propose novel strategies aiming to take advantage of the versatility of NK cells in maintaining immunosurveillance and tissue homeostasis.

Effects of obesity on neuroendocrine, cardiovascular, and immune cell responses to acute psychosocial stress in premenopausal women

OBJECTIVE

To analyze the neuroendocrine and immune cell responses to acute psychosocial stress in obese compared to non-obese premenopausal women.

METHODS

N=15 obese (BMI> or =30) and N=24 (BMI<30) non-obese premenopausal women underwent public speaking stress. State anxiety, ACTH, cortisol, and the redistribution of immune cells were measured before, during, and 10 and 45min after public speaking. Serum hsCRP and serum IL-6 levels were analyzed before, and IL-6 additionally 45min after stress.

RESULTS

In response to public speaking stress, both groups showed significant but comparable increases in state anxiety, plasma ACTH, and blood pressure (all p<0.01; time effects). The cortisol stress response was significantly enhanced in obese women (p<0.05; interaction effect). In addition, heart rate and diastolic blood pressure were significantly higher in obese women 10min following stress (p<0.05, t-tests). Public speaking stress led to a significant increase in IL-6 concentrations (p<0.001; time effect), and obese women displayed higher IL-6 levels both pre- and post-stress (p<0.05; group effect; between-group t-tests: pre-stress p<0.05; post-stress p<0.01). Baseline numbers of circulating leukocytes, granulocytes, CD3+ cells and hsCRP concentration were significantly higher in obese women (between-group t-tests: all p<0.05, but the groups did not differ in the stress-induced redistribution of circulating leukocyte subpopulations.

CONCLUSIONS

Our data reveal a strong association of obesity with chronic low-grade inflammation in premenopausal women. This pro-inflammatory state, together with altered neuroendocrine and cardiovascular stress responsiveness, may conceivably constitute one of the mechanisms linking psychological stress and the long-term health risks associated with obesity.

Stress-induced neurogenic inflammation in murine skin skews dendritic cells towards maturation and migration: key role of intercellular adhesion molecule-1/leukocyte function-associated antigen interactions

The skin continuously serves as a biosensor of multiple exogenous stressors and integrates the resulting responses with an individual's central and peripheral endogenous response systems to perceived stress; it also acts to protect against external challenges such as wounding and infection. We have previously shown in mice that stress induces nerve growth factor- and substance P-dependent neurogenic inflammation, which includes the prominent clustering of MHC class II(+) cells. Because the contribution of dendritic cells (DCs) in response to stress is not well understood, we examined the role of DCs in neurogenic inflammation in murine skin using a well-established murine stress model. We show that sound stress increases the number of intradermal langerin(+) and CD11c(+) DCs and induces DC maturation, as indicated by the up-regulated expression of CD11c, MHC class II, and intercellular adhesion molecule-1 (ICAM-1). Blocking of ICAM-1/leukocyte function-associated antigen-1 interactions significantly abrogated the stress-induced numeric increase, maturation, and migration of dermal DCs in vivo and also reduced stress-induced keratinocyte apoptosis and endothelial cell expression of ICAM-1. In conclusion, stress exposure causes a state of immune alertness in the skin. Such adaptation processes may ensure protection from possible infections on wounding by stressors, such as attack by predators. However, present-day stressors have changed and such adaptations appear redundant and may overrun skin homeostasis by inducing immune dermatoses.

Obesity, depression, and chronic low-grade inflammation in women with polycystic ovary syndrome

BACKGROUND AND OBJECTIVE

Women with polycystic ovary syndrome (PCOS) present with multiple risk factors for cardiovascular diseases at a young age, including obesity and chronic low-grade inflammation. Since depression is common in PCOS, this study aimed to address whether depression correlates with indices of chronic low-grade inflammation beyond the association with obesity.

METHODS

Serum concentrations of IL-6, the stimulated production of IFN-gamma, TNF-alpha, IL-2, IL-4, IL-5, and IL-10, leukocyte numbers, and hsCRP were analyzed in 57 PCOS patients and 28 healthy women, together with clinical parameters, including body mass index (BMI), testosterone, and insulin resistance (HOMA-IR), and psychological parameters, including Beck Depression Inventory (BDI) and health-related quality-of-life (SF-36) scores.

RESULTS

PCOS patients demonstrated significantly increased hsCRP, IL-6, and leukocyte numbers. Group differences in IL-6 and leukocyte numbers, but not hsCRP, disappeared after controlling for BMI. The stimulated production of IFN-gamma, TNF-alpha, IL-2, IL-4, and IL-5 was significantly decreased, irrespective of BMI. In PCOS, hsCRP, IL-6, and leukocyte numbers were correlated with BMI, HDL, diastolic blood pressure, and with insulin resistance. On the other hand, no correlations were found with depression scores or with PCOS-specific endocrine abnormalities. In regression models, BMI was a significant predictor of the key immune markers, and explained a large amount of variance, whereas BDI was not included in either model.

CONCLUSIONS

These data confirm that obesity plays a pivotal role in inflammatory processes relevant to cardiovascular risk in women with PCOS. However, even lean PCOS patients may display subtle alterations in specific aspects of immunity. Our findings did not support a correlation of depression with chronic low-grade inflammation in PCOS.

Stress and reproductive failure: past notions, present insights and future directions

PROBLEM

Maternal stress perception is frequently alleged as a cause of infertility, miscarriages, late pregnancy complications or impaired fetal development. The purpose of the present review is to critically assess the biological and epidemiological evidence that considers the plausibility of a stress link to human reproductive failure.

METHODS

All epidemiological studies published between 1980 and 2007 that tested the link between stress exposure and impaired reproductive success in humans were identified. Study outcomes were evaluated on the basis of how associations were predicted, tested and integrated with theories of etiology arising from recent scientific developments in the basic sciences. Further, published evidence arising from basic science research has been assessed in order to provide a mechanistic concept and biological evidence for the link between stress perception and reproductive success.

RESULTS

Biological evidence points to an immune-endocrine disequilibrium in response to stress and describes a hierarchy of biological mediators involved in a stress trigger to reproductive failure. Epidemiological evidence presents positive correlations between various pregnancy failure outcomes with pre-conception negative life events and elevated daily urinary cortisol. Strikingly, a relatively new conceptual approach integrating the two strands of evidence suggests the programming of stress susceptibility in mother and fetus via a so-called pregnancy stress syndrome.

CONCLUSIONS

An increasing specificity of knowledge is available about the types and impact of biological and social pathways involved in maternal stress responses. The present evidence is sufficient to warrant a reconsideration of conventional views on the etiology of reproductive failure. Physicians and patients will benefit from the adaptation of this integrated evidence to daily clinical practice.