Acute thymic involution in fetuses and neonates with chorioamnionitis

The Fetal Spleen in Low-Risk Pregnancies and prior to Preterm Birth: Observational Study of the Role of Anatomical and Functional Magnetic Resonance Imaging

INTRODUCTION

Spontaneous preterm birth complicates ∼7% of pregnancies and causes morbidity and mortality. Although infection is a common etiology, our understanding of the fetal immune system in vivo is limited. This study aimed to utilize T2-weighted imaging and T2* relaxometry (which is a proxy of tissue oxygenation) of the fetal spleen in uncomplicated pregnancies and in fetuses that were subsequently delivered spontaneously prior to 32 weeks.

METHODS

Women underwent imaging including T2-weighted fetal body images and multi-eco gradient echo single-shot echo planar sequences on a Phillips Achieva 3T system. Previously described postprocessing techniques were applied to obtain T2- and T2*-weighted imaging of the fetal spleen and T2-weighted fetal body volumes.

RESULTS

Among 55 women with uncomplicated pregnancies, an increase in fetal splenic volume, splenic:body volume, and a decrease in splenic T2* signal intensity was demonstrated across gestation. Compared to controls, fetuses who were subsequently delivered prior to 32 weeks' gestation (n = 19) had a larger spleen when controlled for the overall size of the fetus (p = 0.027), but T2* was consistent (p = 0.76).

CONCLUSION

These findings provide evidence of a replicable method of studying the fetal immune system and give novel results on the impact of impending preterm birth on the spleen. While T2* decreases prior to preterm birth in other organs, preservation demonstrated here suggests preferential sparing of the spleen.

Thymic Atrophy and Immune Dysregulation in Infants with Complex Congenital Heart Disease

Congenital heart disease (CHD) is the most common birth defect, and up to 50% of infants with CHD require cardiovascular surgery early in life. Current clinical practice often involves thymus resection during cardiac surgery, detrimentally affecting T-cell immunity. However, epidemiological data indicate that CHD patients face an elevated risk for infections and immune-mediated diseases, independent of thymectomy. Hence, we examined whether the cardiac defect impacts thymus function in individuals with CHD. We investigated thymocyte development in 58 infants categorized by CHD complexity. To assess the relationship between CHD complexity and thymic function, we analyzed T-cell development, thymic output, and biomarkers linked to cardiac defects, stress, or inflammation. Patients with highly complex CHD exhibit thymic atrophy, resulting in low frequencies of recent thymic emigrants in peripheral blood, even prior to thymectomy. Elevated plasma cortisol levels were detected in all CHD patients, while high NT-proBNP and IL-6 levels were associated with thymic atrophy. Our findings reveal an association between complex CHD and thymic atrophy, resulting in reduced thymic output. Consequently, thymus preservation during cardiovascular surgery could significantly enhance immune function and the long-term health of CHD patients.

Small fetal thymus and adverse perinatal outcome in maternal vasculitis: A prospective case-control study

BACKGROUND

Ultrasonographic evaluation of fetal thymus size may be used to predict the adverse perinatal outcome in pregnant women with vasculitis.

AIM

To compare fetal thymus size in pregnant women with vasculitis and healthy pregnant women and to evaluate whether fetal thymus size predicts the adverse perinatal outcome.

METHODS

Twenty-two pregnant women with previously diagnosed vasculitis, 18 of them with Behçet's disease, three with Takayasu arteritis, and one with Wegener's granulomatosis, were included in the case group. The control group comprised 66 healthy pregnant women whose gestational ages matched the case group. Thymic thoracic ratio (TTR) was measured to assess fetal thymus size in the view of three vessels and trachea.

RESULTS

In the case group, fetal TTR was significantly lower (0.32 ± 0.03 vs. 0.36 ± 0.02, p = < 0.001). Fetal TTR was significantly lower in those using prednisone than those not (p = .001) in the case group. There was no significant difference in fetal TTR between colchicine used and not used (p = .078) in the case group. Also, for the TTR, a sensitivity of 100% and a specificity of 92% were achieved with a cut-off value of 0.33 for predicting adverse perinatal outcomes.

CONCLUSION

The fetuses of pregnant women with maternal vasculitis had a smaller TTR. The small fetal thymus may alert clinicians to possible adverse perinatal outcomes and, with other supporting risk factors, may help predict adverse perinatal outcomes in pregnant women with vasculitis.

Antenatal diagnosis of chorioamnionitis: A review of the potential role of fetal and placental imaging

Chorioamnionitis is present in up to 70% of spontaneous preterm births. It is defined as an acute inflammation of the chorion, with or without involvement of the amnion, and is evidence of a maternal immunological response to infection. A fetal inflammatory response can coexist and is diagnosed on placental histopathology postnatally. Fetal inflammatory response syndrome (FIRS) is associated with poorer fetal and neonatal outcomes. The only antenatal diagnostic test is amniocentesis which carries risks of miscarriage or preterm birth. Imaging of the fetal immune system, in particular the thymus and the spleen, and the placenta may give valuable information antenatally regarding the diagnosis of fetal inflammatory response. While ultrasound is largely limited to structural information, MRI can complement this with functional information that may provide insight into the metabolic activities of the fetal immune system and placenta. This review discusses fetal and placental imaging in pregnancies complicated by chorioamnionitis and their potential future use in achieving non-invasive antenatal diagnosis. This article is protected by copyright. All rights reserved.

Ultrasonographic evaluation of the fetal thymic-thoracic ratio and its association with conotruncal heart defects

OBJECTIVE

To evaluate the thymic-thoracic ratio (TT ratio) on fetal ultrasound and its association with conotruncal heart defects.

METHODS

A case control study was carried out to retrospectively assess the TT ratio on fetal echocardiograms performed between 19 and 39 weeks of gestation, showing congenital heart defects, from January to December 2018. The control group was comprised of fetuses with no echocardiogram evidence of congenital cardiac malformations. Cases of multiple pregnancies and patients where the TT ratio could not be established have been excluded.

RESULTS

A total of 338 pregnancies have been analysed. Fifty-two pregnancies were diagnosed with fetal heart defects (15%), 17 of which showed conotruncal heart defects (32.7%). The TT ratio in normal fetuses (286 pregnancies) increased with gestational age, and had an average of 0.43 ± 0.06. Compared to the control group (normal fetuses), fetuses with conotruncal heart defects had significantly lower mean TT ratio (0.33 ± 0.07). Those that were diagnosed with nonconotruncal heart defects did not show any statistically significant difference in the TT ratios compared with the control group (0.40 ± 0.09 vs. 0.43 ± 0.06, respectively).

CONCLUSION

The TT ratio was significantly lower in fetuses with conotruncal heart defects compared with both the control group (normal fetuses) and the fetuses with nonconotruncal heart defects.

First trimester fetal thymus volume may predict preeclampsia

OBJECTIVE

The immunological factors have role in the development of preeclampsia. The thymus is one of the main organs of the fetal immune system. The aim of this prospective clinical study was to investigate the association between fetal thymus volume and preeclampsia by adding the 3-dimensional measurement of thymus volume to the routine fetal ultrasound scan at 11-14 week of gestation.

STUDY DESIGN

Totally 72 pregnant women in their first trimester of pregnancy were included and 3-D fetal thymus volume was measured with sonographic VOCAL programme. All women gestational period was followed. The data of women with preeclampsia (n = 10, study group) and without preeclampsia (n = 62, control group) were compared.

MAIN OUTCOME MEASURES

Fetal thymus volume, preeclampsia development.

RESULTS

Fetal thymus volume, mean gestational age at birth and newborn birthweight were found to be statistically lower in cases with preeclampsia compared with those without any complications. When the fetal thymus volume measured by the VOCAL programme in the study group was used as a marker for preeclampsia development, the limit value was 0.0375 cm³; sensitivity was 87.1% and specificity was 50% (AUC 85.3%, P < .001, 95% CI 0.751-0.949). As a result of binary logistic regression analysis; the low fetal thymus volume measured at 11-14 gestational weeks can be used as a predictive factor for preeclampsia (P < .001).

CONCLUSIONS

According to the results of this study; the development of preeclampsia may be predicted by measuring 3-D fetal thymus volume at the first trimester.

The Distinct Immune Nature of the Fetal Inflammatory Response Syndrome Type I and Type II

Fetal inflammatory response syndrome (FIRS) is strongly associated with neonatal morbidity and mortality and can be classified as type I or type II. Clinically, FIRS type I and type II are considered as distinct syndromes, yet the molecular underpinnings of these fetal inflammatory responses are not well understood because of their low prevalence and the difficulty of postdelivery diagnosis. In this study, we performed RNA sequencing of human cord blood samples from preterm neonates diagnosed with FIRS type I or FIRS type II. We found that FIRS type I was characterized by an upregulation of host immune responses, including neutrophil and monocyte functions, together with a proinflammatory cytokine storm and a downregulation of T cell processes. In contrast, FIRS type II comprised a mild chronic inflammatory response involving perturbation of HLA transcripts, suggestive of fetal semiallograft rejection. Integrating single-cell RNA sequencing-derived signatures with bulk transcriptomic data confirmed that FIRS type I immune responses were mainly driven by monocytes, macrophages, and neutrophils. Last, tissue- and cell-specific signatures derived from the BioGPS Gene Atlas further corroborated the role of myeloid cells originating from the bone marrow in FIRS type I. Collectively, these data provide evidence that FIRS type I and FIRS type II are driven by distinct immune mechanisms; whereas the former involves the innate limb of immunity consistent with host defense, the latter resembles a process of semiallograft rejection. These findings shed light on the fetal immune responses caused by infection or alloreactivity that can lead to deleterious consequences in neonatal life.

Assessment of the fetal thymus gland: Comparing MRI-acquired thymus volumes with 2D ultrasound measurements

OBJECTIVES

The fetal thymus gland has been shown to involute in response to intrauterine infection, and therefore could be used as a non-invasive marker of fetal compartment infection. The objective of this study was to evaluate how accurately 2D ultrasound-derived measurements of the fetal thymus reflect the 3D volume of the gland derived from motion corrected MRI images.

STUDY DESIGN

A retrospective study was performed using paired ultrasound and MRI datasets from the iFIND project (http://www.ifindproject.com). To obtain 3D volumetry of the thymus gland, T2-weighted single shot turbo spin echo (ssTSE) sequences of the fetal thorax were acquired. Thymus volumes were manually segmented from deformable slice-to-volume reconstructed images. To obtain 2D ultrasound measurements, previously stored fetal cine loops were used and measurements obtained at the 3-vessel-view (3VV) and 3-vessel-trachea view (3VT): anterior-posterior diameter (APD), intrathoracic diameter (ITD), transverse diameter (TD), perimeter and 3-vessel-edge (3VE). Inter-observer and intra-observer reliability (ICC) was calculated for both MRI and ultrasound measurements. Pearson correlation coefficients (PCC) were used to compare 2D-parameters with acceptable ICC to TV.

RESULTS

38 participants were identified. Adequate visualisation was possible on 37 MRI scans and 31 ultrasound scans. Of the 30 datasets where both MRI and ultrasound data were available, MRI had good interobserver reliability (ICC 0.964) and all ultrasound 3VV 2D-parameters and 3VT 3VE had acceptable ICC (>0.75). Four 2D parameters were reflective of the 3D thymus volume: 3VV TD r = 0.540 (P = 0.002); 3VV perimeter r = 0.446 (P = 0.013); 3VV APD r = 0.435 (P = 0.110) and 3VT TD r = 0.544 (P = 0.002).

CONCLUSIONS

MRI appeared superior to ultrasound for visualization of the thymus gland and reproducibility of measurements. Three 2D US parameters, 3VV TD, perimeter and 3VT APD, correlated well with TV. Therefore, these represent a more accurate reflection of the true size of the gland than other 2D measurements, where MRI is not available.

Antenatal thymus volumes in fetuses that delivered <32 weeks' gestation: An MRI pilot study

INTRODUCTION

Infection and inflammation have been implicated in the etiology and subsequent morbidity associated with preterm birth. At present, there are no tests to assess for fetal compartment infection. The thymus, a gland integral in the fetal immune system, has been shown to involute in animal models of antenatal infection, but its response in human fetuses has not been studied. This study aims: (a) to generate magnetic resonance imaging (MRI) -derived fetal thymus volumes standardized for fetal weight; (b) to compare standardized thymus volumes from fetuses that delivered before 32 weeks of gestation with fetuses that subsequently deliver at term; (c) to assess thymus size as a predictor of preterm birth; and (d) to correlate the presence of chorioamnionitis and funisitis at delivery with thymic volumes in utero in fetuses that subsequently deliver preterm.

MATERIAL AND METHODS

Women at high-risk of preterm birth at 20-32 weeks of gestation were recruited. A control group was obtained from existing data sets acquired as part of three research studies. A fetal MRI was performed on a 1.5T or 3T MRI scanner: T2 weighted images were obtained of the entire uterine content and specifically the fetal thorax. A slice-to-volume registration method was used for reconstruction of three-dimensional images of the thorax. Thymus segmentations were performed manually. Body volumes were calculated by manual segmentation and thymus:body volume ratios were generated. Comparison of groups was performed using multiple regression analysis. Normal ranges were created for thymus volume and thymus:body volume ratios using the control data. Receiver operating curves (ROC) curves were generated for thymus:body volume ratio and gestation-adjusted thymus volume centiles as predictors of preterm birth. Placental histology was analyzed where available from pregnancies that delivered very preterm and the presence of chorioamnionitis/funisitis was noted.

RESULTS

Normative ranges were created for thymus volume, and thymus volume was standardized for fetal size from fetuses that subsequently delivered at term, but were imaged at 20-32 weeks of gestation. Image data sets from 16 women that delivered <32 weeks of gestation (ten with ruptured membranes and six with intact membranes) and 80 control women that delivered >37 weeks were included. Mean gestation at MRI of the study group was 28⁺⁴  weeks (SD 3.2) and for the control group was 25⁺⁵  weeks (SD 2.4). Both absolute fetal thymus volumes and thymus:body volume ratios were smaller in fetuses that delivered preterm (P < .001). Of the 16 fetuses that delivered preterm, 13 had placental histology, 11 had chorioamnionitis, and 9 had funisitis. The strongest predictors of prematurity were the thymus volume Z-score and thymus:body volume ratio Z-score (ROC areas 0.915 and 0.870, respectively).

CONCLUSIONS

We have produced MRI-derived normal ranges for fetal thymus and thymus:body volume ratios between 20 and 32 weeks of gestation. Fetuses that deliver very preterm had reduced thymus volumes when standardized for fetal size. A reduced thymus volume was also a predictor of spontaneous preterm delivery. Thymus volume may be a suitable marker of the fetal inflammatory response, although further work is needed to assess this, increasing the sample size to correlate the extent of chorioamnionitis with thymus size.

Genome-wide postnatal changes in immunity following fetal inflammatory response

The fetal inflammatory response (FIR) increases the risk of perinatal brain injury, particularly in extremely low gestational age newborns (ELGANs, < 28 weeks of gestation). One of the mechanisms contributing to such a risk is a postnatal intermittent or sustained systemic inflammation (ISSI) following FIR. The link between prenatal and postnatal systemic inflammation is supported by the presence of well‐established inflammatory biomarkers in the umbilical cord and peripheral blood. However, the extent of molecular changes contributing to this association is unknown. Using RNA sequencing and mass spectrometry proteomics, we profiled the transcriptome and proteome of archived neonatal dried blood spot (DBS) specimens from 21 ELGANs. Comparing FIR‐affected and unaffected ELGANs, we identified 782 gene and 27 protein expression changes of 50% magnitude or more, and an experiment‐wide significance level below 5% false discovery rate. These expression changes confirm the robust postnatal activation of the innate immune system in FIR‐affected ELGANs and reveal for the first time an impairment of their adaptive immunity. In turn, the altered pathways provide clues about the molecular mechanisms triggering ISSI after FIR, and the onset of perinatal brain injury.

Databases

EGAS00001003635 (EGA); PXD011626 (PRIDE).

The fetal inflammatory response syndrome: the origins of a concept, pathophysiology, diagnosis, and obstetrical implications

The fetus can deploy a local or systemic inflammatory response when exposed to microorganisms or, alternatively, to non-infection-related stimuli (e.g., danger signals or alarmins). The term "Fetal Inflammatory Response Syndrome" (FIRS) was coined to describe a condition characterized by evidence of a systemic inflammatory response, frequently a result of the activation of the innate limb of the immune response. FIRS can be diagnosed by an increased concentration of umbilical cord plasma or serum acute phase reactants such as C-reactive protein or cytokines (e.g., interleukin-6). Pathologic evidence of a systemic fetal inflammatory response indicates the presence of funisitis or chorionic vasculitis. FIRS was first described in patients at risk for intraamniotic infection who presented preterm labor with intact membranes or preterm prelabor rupture of the membranes. However, FIRS can also be observed in patients with sterile intra-amniotic inflammation, alloimmunization (e.g., Rh disease), and active autoimmune disorders. Neonates born with FIRS have a higher rate of complications, such as early-onset neonatal sepsis, intraventricular hemorrhage, periventricular leukomalacia, and death, than those born without FIRS. Survivors are at risk for long-term sequelae that may include bronchopulmonary dysplasia, neurodevelopmental disorders, such as cerebral palsy, retinopathy of prematurity, and sensorineuronal hearing loss. Experimental FIRS can be induced by intra-amniotic administration of bacteria, microbial products (such as endotoxin), or inflammatory cytokines (such as interleukin-1), and animal models have provided important insights about the mechanisms responsible for multiple organ involvement and dysfunction. A systemic fetal inflammatory response is thought to be adaptive, but, on occasion, may become dysregulated whereby a fetal cytokine storm ensues and can lead to multiple organ dysfunction and even fetal death if delivery does not occur ("rescued by birth"). Thus, the onset of preterm labor in this context can be considered to have survival value. The evidence so far suggests that FIRS may compound the effects of immaturity and neonatal inflammation, thus increasing the risk of neonatal complications and long-term morbidity. Modulation of a dysregulated fetal inflammatory response by the administration of antimicrobial agents, anti-inflammatory agents, or cell-based therapy holds promise to reduce infant morbidity and mortality.

A perfect storm: fetal inflammation and the developing immune system

Histologic chorioamnionitis is an inflammatory disorder of the placenta that commonly precedes preterm delivery. Preterm birth related to chorioamnionitis and fetal inflammation has been associated with a risk for serious inflammatory complications in infancy. In addition, preterm infants exposed to chorioamnionitis may be more susceptible to infection in the neonatal intensive care unit and possibly later in life. A significant body of work has established an association between chorioamnionitis and inflammatory processes. However, the potential consequences of this inflammation on postnatal immunity are less understood. In this review, we will discuss current knowledge regarding the effects of fetal exposure to inflammation on postnatal immune responses.

Screening of the growth of thymus of human fetuses

The thymus is a lymphoepithelial organ, and its morphometry is commonly utilized for surveillance of the immunological status of fetus and neonates. Many studies showed that fetal thymus size is used as a prognostic indicator for pregnancy-related disorders such as eclampsia, preterm labor, and gestational diabetes. The study aims to establish reference ranges of the normal fetal thymus size between 12 and 40 weeks of gestational age (GA). The study was conducted on 89 fetuses. They were dissected to capture the morphometry of thymus: transverse diameter, perimeter, and weight. Considering these parameters were dependent variables of GA and gestational weight (GW). Their relationship was studied by a multiple regression model. The best fit models in predicting thymic dimensions as a function of GA and GW were determined using regression analysis. Mean transverse diameter, perimeter, and thymus weight was 33.45±2.91 mm, 125.72±55.4 mm, and 3.078±3.06 g, respectively. They were increased throughout pregnancy as GA and GW advanced. The regression equation for a transverse diameter of the thymus as a function of GA was (0.303×GA-4.885, R²=0.8196) and for the perimeter of the thymus was (1.0212×GA-15.24, R²=0.8666). Reference ranges and baseline data of the normal fetal thymic dimensions between 12 and 40 weeks of GA have been established.

Association between histological alterations in the thymus and sudden infant death syndrome

INTRODUCTION

Sudden infant death syndrome (SIDS) involves the death of an infant during the first year of life and it is among the leading causes of infant mortality worldwide. One hypothesis regarding the pathogenesis of SIDS is that it results from a combination of three independent factors: endogenous vulnerability, a critical time window during postnatal development, and exogenous stressors. This hypothesis is known as the "triple-risk model".

METHODS

In this study, we used an immunohistological approach to compare the cellular microenvironments of thymuses from 19 infants whose sudden death was classified as SIDS and a control group, which consisted of thymuses from age-matched children undergoing surgery for various congenital heart defects. We hypothesized that morphological signs of stress-related thymic involution would be present.

RESULTS

Based on our observations, we found evidence that the proliferation and maturation of T-lymphocytes in the thymuses of infants with SIDS were suppressed. We observed enhanced macrophage activity, suggesting an increase in the apoptosis of lymphocytes and decrease in number of thymic dendritic cells and myoid cells. Significant apoptosis of thymic lymphocytes without cell regeneration typically leads to atrophy of the thymus. All cellular events we observed resemble the initial stage of stress-related thymic involution.

CONCLUSION

These results support the "triple-risk model," suggesting that certain exogenous stressors might be involved in the pathogenesis of SIDS. This was probably not recognized during the autopsies of infants who died suddenly.

Small fetal thymus and adverse obstetrical outcome: a systematic review and a meta-analysis

INTRODUCTION

The aim of this study was to explore the association between small fetal thymus on ultrasound and adverse obstetrical outcome.

MATERIAL AND METHODS

Medline, Embase, Cochrane and Web of Science databases were searched. Primary outcome was the risk of preterm birth before 37 and 34 weeks of gestation in fetuses with, compared to those without, a small thymus on ultrasound.

SECONDARY OUTCOMES

occurrence of chorioamnionitis, intrauterine growth restriction, neonatal sepsis, gestational age at birth, birthweight, neonatal morbidity and preeclampsia.

RESULTS

Twelve studies including 1744 fetuses who had ultrasound assessment of thymus during pregnancy were included. Women with preterm premature rupture of the membranes or with preterm labor were at higher risk of preterm birth before 37 weeks (p = 0.01), or before 34 weeks (p < 0.001) for fetuses with a small fetal thymus compared to those without a small thymus, and the risk of chorioamnionitis was higher when the thymus was small (p < 0.001). Fetuses with small thymus were not at higher risk of intrauterine growth restriction (p = 0.3). A small thymus increased the risk of neonatal sepsis (p = 0.007) and morbidity (p = 0.003), but not the risk of preeclampsia (p = 0.9).

CONCLUSIONS

A small fetal thymus is associated with a higher risk of preterm birth, chorioamnionitis, neonatal sepsis and morbidity, but not with intrauterine growth restriction and preeclampsia.

Sonographic measurement of the fetal thymus: Relationship with maternal obesity

BACKGROUND

The purpose of this study was to evaluate the influence of maternal obesity on the size of the fetal thymus.

METHODS

The study population consisted of 138 pregnant women who were divided into two groups based on their body mass index (BMI): Normal-weight group (n = 97; BMI: 18-25 kg/m² ) and obese group (n = 41; BMI: ≥ 30 kg/m² ). All participants underwent routine second-trimester prenatal ultrasound (US) screening at 20-25 weeks of gestation. Differences in US measurement of fetal thymus, fetal anthropometric measurements, subcutaneous adipose tissue thickness, fetal weight, gestational age, white blood cell count, and C-reactive protein (CRP) values between groups were compared.

RESULTS

The mean thymus size was 18.7 ± 2.9 mm for normal-weight group, and 21.6 ± 3.7 mm for the obese group (p < 0.001). CRP values were also significantly different between groups (6.8 ± 4.4 mg/dl for normal-weight group, 14.8 ± 1.8 mg/dl for obese group, p < 0.001).

CONCLUSIONS

Fetal thymus size was increased in obese women, and this increase may indicate immunologic abnormalities in fetuses. However, future large-scale studies are necessary to support this association. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:277-281, 2017.

Acute Thymic Involution and Mechanisms for Recovery

Acute thymic involution (ATI) is usually regarded as a virulence trait. It is caused by several infectious agents (bacteria, viruses, parasites, fungi) and other factors, including stress, pregnancy, malnutrition and chemotherapy. However, the complex mechanisms that operate during ATI differ substantially from each other depending on the causative agent. For instance, a transient reduction in the size and weight of the thymus and depletion of populations of T cell subsets are hallmarks of ATI in many cases, whereas severe disruption of the anatomical structure of the organ is also associated with some factors, including fungal, parasitic and viral infections. However, growing evidence shows that ATI may be therapeutically halted or reversed. In this review, we highlight the current progress in this field with respect to numerous pathological factors and discuss the possible mechanisms. Moreover, these new observations also show that ATI can be mechanistically reversed.

Adrenal Histologic Stress-related Changes in Third Trimester Stillbirth

Adrenal histologic changes, including compact cell change (CCC), cystic change (CYC), and adrenal hemorrhage (AH), and their clinical correlations have only infrequently been investigated in stillbirth. We evaluated 75 third trimester singleton stillborns with complete autopsies (30 term and 45 preterm). A total of 58 had unexplained stillbirth and 17 had clinical placental abruption. The mothers were predominantly African-American (89%). CCC and CYC were diagnosed as cytoplasmic eosinophilia and cystic cavities in the definitive cortex, respectively. Adrenal changes were correlated with acute thymic involution (ATI), thymic petechiae, and clinical features, including abruption. CCC, CYC, and AH were present in 58 (77%), 51 (68%), and 15 (20%) of the 75 stillborns, respectively. CCC and CYC were frequently seen together ( P < .001). CCC and CYC were associated with higher ATI grade ( P < .001 and P = .010, respectively). The presence of CCC, but not CYC, was associated with absence of thymic petechiae ( P = .013) and was more frequent with unexplained stillbirth compared to abruption ( P = .017). AH was associated with lower ATI grade ( P = .002), with thymic petechiae ( P < .001), and with abruption ( P = .004). CYC was associated with diabetes ( P = .015). Overall, CCC and CYC were frequent findings and correlated with higher ATI grade, suggesting similar causes and time frames. CCC, but not CYC, correlated with unexplained stillbirth compared to abruption, but its high frequency in both groups limits its usefulness in their separation. AH was more frequent in the abruption group and correlated with lower ATI grade and thymic petechiae, supporting an association with sudden asphyxial death.

Characterization of nanoporous structures: from three dimensions to two dimensions

The scanning electron microscope (SEM) has revealed a colorful three-dimensional world due to its great depth of field. However, the abundance of structural information imposes tough challenges to quantitative image analysis. In the current investigation, we developed a SEM-image polishing (SIP) based quantitative SEM-image analysis (QSIA) technique. As an example, QSIA was employed to characterize nanoporous silica. The results confirmed that the nanoporous silica samples, processed via sol-gel methods, were single-parameter, with the pore size being the only variable. The QSIA technique may pave the way to fast and accurate data mining of nanoscaled materials.

Ultrasonographic approach to diagnosis of fetal inflammatory response syndrome: a tool for at-risk fetuses?

Preterm parturition is a syndrome that may result from many underlying mechanisms. Infection and inflammation are the prominent ones. Intrauterine infection and inflammation have an effect akin to sepsis, and that is similar to systemic inflammatory response in adults. Indeed, there is evidence to support the association of a fetal inflammatory response syndrome (FIRS) to systemic infection and inflammation. The utilization of invasive procedures for the prenatal diagnosis of FIRS is associated with a risk for complications resulting from the invasive method. The progress in the imaging quality of obstetrical ultrasound and the development of novel methods for functional anatomical assessment of the fetal organs may help to identify, noninvasively, fetuses at risk for FIRS in patients presenting with preterm labor. We review the studies describing advanced sonographic modalities and the imaging findings in the heart, thymus, kidney, adrenal glands, and spleen of these fetuses.

Second-Trimester Sonographic Thymus Measurements Are Not Associated With Preterm Birth and Other Adverse Obstetric Outcomes

OBJECTIVES

Previous studies have demonstrated an association between adverse obstetric outcomes, such as preterm birth, and in utero inflammation. The fetal thymus, which can be visualized in the anterior mediastinum on obstetric sonography, may involute in response to such inflammation and thus may identify pregnancies at increased risk for these outcomes. We therefore sought to determine whether second-trimester fetal thymus measurements are associated with preterm birth.

METHODS

Transabdominal fetal thymus measurements were prospectively obtained in singleton pregnancies at gestational ages of 18 weeks to 23 weeks 6 days during a 5-month period. The transverse and anterorposterior thymus diameters and the thymic-thoracic ratio were measured. Delivery outcomes were collected from our clinical database. The primary outcome was preterm birth, which we defined as delivery between 24 weeks and 36 weeks 6 days. Small for gestational age (SGA) and pregnancy-related hypertension, which are adverse obstetric outcomes that may also be associated with in utero inflammation, were included as secondary outcomes.

RESULTS

We included 520 patients with thymus measurements and obstetric outcome data. The prevalence of preterm birth was 12.3% (n = 64). None of the thymus measurements were associated with preterm birth. Similarly, there was no association between thymus measurements and SGA or pregnancy-related hypertension.

CONCLUSIONS

Sonographic assessment of the second-trimester fetal thymus did not identify patients at increased risk for preterm birth, SGA, and pregnancy-related hypertension. Routine thymus measurements during the second-trimester anatomic scan are not clinically useful for prediction of preterm birth and other adverse outcomes.

Lipopolysaccharide-Induced Chorioamnionitis Promotes IL-1-Dependent Inflammatory FOXP3+ CD4+ T Cells in the Fetal Rhesus Macaque

Chorioamnionitis is associated with preterm labor and fetal inflammatory response syndrome (FIRS), causing fetal organ injury and morbidity, particularly in extremely premature infants. However, the effects of inflammation on the fetal immune system remain poorly understood, due to the difficulty of studying immune development in infants. Therefore, we used the model of intra-amniotic LPS administered at ∼80% gestation in rhesus monkeys to cause chorioamnionitis and FIRS that is similar in human pathology. Importantly, the frequency of IL-17(+) and IL-22(+) CD4(+) T cells increased in the spleen of LPS-exposed fetuses, whereas regulatory T cell (Treg) frequency decreased. These changes persisted for at least 48 h. Notably, Th17 cytokines were predominantly expressed by FOXP3(+)CD4(+) T cells and not by their FOXP3(-) counterparts. Bifunctional IL-17(+)FOXP3(+) exhibited a phenotype of inflammatory Tregs (RORc(High/+), Helios(Low/-), IL-2(+), IFN-γ(+), and IL-8(+)) compared with typical FOXP3(+) cells. Diminished splenic Treg frequency in LPS-exposed fetuses was associated with inadequate Treg generation in the thymus. Mechanistically, the emergence of inflammatory Tregs was largely dependent on IL-1 signaling. However, blockage of IL-1R signaling did not abolish the deleterious effects of LPS on Treg frequency in the thymus or spleen. Collectively, we demonstrate that a prenatal inflammatory environment leads to inadequate Treg generation in the thymus with a switch of splenic Tregs toward an inflammatory phenotype. Both processes likely contribute to the pathogenesis of chorioamnionitis. Approaches to manipulate Treg numbers and function could thus be useful therapeutically to alleviate FIRS in preterm infants.

Acute Placental Villitis as Evidence of Fetal Sepsis: An Autopsy Case Report

Acute placental villitis is very rare and believed to reflect overwhelming fetal sepsis in utero, commonly caused by Escherichia coli or group B streptococci. We present a case of intrauterine fetal death associated with acute placental villitis and acute necrotizing chorioamnionitis by early-onset group B streptococcal infection. A 36-year-old woman presented with decreased fetal movement and fever at 21 weeks of gestation. Ultrasound demonstrated intrauterine fetal death. After delivery, the placenta revealed multifocal neutrophilic infiltration in chorionic villi, most prominently beneath the trophoblast basement membrane, which was also accompanied by acute necrotizing chorioamnionitis. Gram-positive microorganisms were detected in villous vessels as well as in the major organs of the fetus, which was consistent with Streptococcus agalactiae (group B) cultured from maternal blood. Acute placental villitis should be recognized as evidence of fetal sepsis that often has lethal clinical outcome, as compared to intra-amniotic infection associated with acute chorioamnionitis alone.

The use of imaging technology in the assessment of the fetal inflammatory response syndrome-imaging of the fetal thymus

The fetal inflammatory response syndrome (FIRS) describes a state of extensive fetal multi organ involvement during chorioamnionitis, and is associated with grave implications on perinatal outcome. The syndrome has been linked to the preterm parturition syndrome and is associated with inflammation/infection processes in most of the fetal organs. The fetal thymus, a major organ in the developing immune system involutes during severe neonatal disease and has been shown to be smaller in fetuses with FIRS. Various methods for imaging of the fetal thymus and measurement are described. Currently the only method to diagnose FIRS prenatally is through amniocentesis. We suggest that women who are admitted with preterm labor with intact membranes and those with PPROM should have a detailed sonographic examination of the fetal thymus as a surrogate marker of fetal involvement in intrauterine infection/inflammation processes.

Clinical chorioamnionitis at term V: umbilical cord plasma cytokine profile in the context of a systemic maternal inflammatory response

OBJECTIVE

Microbial invasion of the fetus due to intra-amniotic infection can lead to a systemic inflammatory response characterized by elevated concentrations of cytokines in the umbilical cord plasma/serum. Clinical chorioamnionitis represents the maternal syndrome often associated with intra-amniotic infection, although other causes of this syndrome have been recently described. The objective of this study was to characterize the umbilical cord plasma cytokine profile in neonates born to mothers with clinical chorioamnionitis at term, according to the presence or absence of bacteria and/or intra-amniotic inflammation.

MATERIALS AND METHODS

A cross-sectional study was conducted, including patients with clinical chorioamnionitis at term (n=38; cases) and those with spontaneous term labor without clinical chorioamnionitis (n=77; controls). Women with clinical chorioamnionitis were classified according to the results of amniotic fluid culture, broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry (PCR/ESI-MS) and amniotic fluid interleukin (IL)-6 concentration into three groups: 1) no intra-amniotic inflammation; 2) intra-amniotic inflammation without detectable microorganisms; or 3) microbial-associated intra-amniotic inflammation. A fetal inflammatory response syndrome (FIRS) was defined as an umbilical cord plasma IL-6 concentration >11 pg/mL. The umbilical cord plasma concentrations of 29 cytokines were determined with sensitive and specific V-PLEX immunoassays. Nonparametric statistical methods were used for analysis, adjusting for a false discovery rate of 5%.

RESULTS

1) Neonates born to mothers with clinical chorioamnionitis at term (considered in toto) had significantly higher median umbilical cord plasma concentrations of IL-6, IL-12p70, IL-16, IL-13, IL-4, IL-10 and IL-8, but significantly lower interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF)-α concentrations than neonates born to mothers with spontaneous term labor without clinical chorioamnionitis; 2) neonates born to mothers with clinical chorioamnionitis at term but without intra-amniotic inflammation had higher concentrations of IL-6, IL-12p70, IL-13, IL-4, IL-5, and IL-8, but lower IFN-γ, than neonates not exposed to clinical chorioamnionitis, suggesting that maternal fever in the absence of intra-amniotic inflammation leads to a change in the fetal cytokine network; 3) there were significant, positive correlations between maternal and umbilical cord plasma IL-6 and IL-8 concentrations (IL-6: Spearman correlation=0.53; P<0.001; IL-8: Spearman correlation=0.42; P<0.001), consistent with placental transfer of cytokines; 4) an elevated fetal plasma IL-6 (>11 pg/mL), the diagnostic criterion for FIRS, was present in 21% of cases (8/38), and all these neonates were born to mothers with proven intra-amniotic infection; and 5) FIRS was associated with a high concentration of umbilical cord plasma IL-8, IL-10 and monocyte chemoattractant protein (MCP)-1.

CONCLUSIONS

Neonates born to mothers with clinical chorioamnionitis at term had higher concentrations of umbilical cord plasma cytokines than those born to mothers without clinical chorioamnionitis. Even neonates exposed to clinical chorioamnionitis but not to intra-amniotic inflammation had elevated concentrations of multiple cytokines, suggesting that intrapartum fever alters the fetal immune response.

Acute thymic involution in unexplained third trimester stillbirth: frequency, grade, and correlation with neuropathologic injury

Many 3rd-trimester stillbirths are unexplained, including the time course of the illness. Histologic acute thymic involution (ATI), when graded, correlates with duration of acute illness (grade 0, <12 hours; grade 4, >72 hours). Histologic brain injury is also common in stillbirth. We investigated ATI in unexplained stillbirth and correlated it with neuropathologic injury by identifying 58 autopsies of unexplained, 3rd-trimester stillborns (preterm, n  =  24; term, n  =  34) that included brain examination and graded ATI from 0 (resting state) to 4 (pronounced lymphodepletion). Gray matter injury (GMI) and white matter injury (WMI) were classified as older, recent, or absent, and ATI was correlated with GMI, WMI, thymic weight, and clinical data. Nine cases (16%) had ATI grade 0-1; 19 (33%), grade 2; 24 (41%), grade 3; and 6 (10%), grade 4. Older GMI and WMI were present in 39 (67%) and 10 (17%) stillborns, respectively. Higher ATI grade correlated significantly with older GMI (P < 0.001) and WMI (P  =  0.014). The ATI grade was higher in the small-for-gestational stillborns compared with the appropriate- or large-for-gestational stillborns (P  =  0.017) but did not correlate significantly with gestational age or other clinical or demographic factors evaluated. The ATI grades 2-4 were found in 84% of the stillborns, consistent with onset of acute illness between 24 and >72 hours before demise. Higher ATI grade correlated significantly with older brain injury, suggesting similar time of onset and shared underlying pathophysiologic events, the specific nature of which remains unclear.

Fetal thymus volume estimation by virtual organ computer-aided analysis in normal pregnancies

OBJECTIVES

The thymus has a pyramidal shape, which is best shown in coronal planes. The aim of this study was to evaluate the potential of virtual organ computer-aided analysis to estimate fetal thymus volume in normal pregnancies.

METHODS

Three-dimensional volume data sets from the axial upper mediastinal section were acquired from 37 normal pregnancies between 12 and 35 weeks' gestation. Thymus volume was calculated by virtual organ computer-aided analysis by 2 separate examiners. In 12 cases, volumes were also acquired with 4-dimensional sonography and spatiotemporal image correlation software to assess the variability in thymus size between the systolic and diastolic periods of fetal heart motion. Linear regression analysis was used to assess the relationship between the fetal thymus volume and gestational age. Paired Student t tests were used to evaluate both the level of agreement for interobserver and intraobserver variability and the difference between diastolic and systolic thymus volumes.

RESULTS

Identification of the borders of the thymus and calculation of its volume were successful in 28 patients (77.7%). Statistically significant linear growth of the thymus during pregnancy, from 12 to 35 weeks, was found. The growth coefficient for each gestational age was 0.43 (95% confidence interval, 0.355 to 0.504; P < .001). The difference in thymus size between systole and diastole was minor (0.0798 cm(3); 95% confidence interval, -0.044 to 0.203 cm(3)). Interobserver and intraobserver variability was not statistically significant.

CONCLUSIONS

Although the thymus has a complex shape, it was possible to determine its borders and to calculate its volume by virtual organ computer-aided analysis in 77.7% of cases. Linear growth during pregnancy was found, and the minor changes during systole and diastole could be explained by condensation of the soft tissue of the thymus secondary to cardiac activity.

Fatty infiltration of the thymus in response to illness in the pediatric population

Under physiologic stress, glucocorticoids contribute to thymic involution. While steroids enhance fatty infiltration, this change has not been well studied in the pediatric thymus during illness. Evaluation of 130 thymuses from fetuses, infants and children determined the frequency of thymic fatty infiltration to be low (25%), particularly in fetal thymus (4%). In most cases, fatty infiltration was focal. There was a significant correlation with duration of illness, but not with patient age, gestational age, or underlying disease. There was significantly less fatty infiltration in fetal thymus compared to post-natal thymus, for the same degree of thymic involution. Only seven cases showed diffuse thymic fatty infiltration; all were post-natal associated with an infectious etiology. In contrast, fetal cases of chorioamnionitis seldom showed fatty infiltration and only focally, implying the stress response of fetal thymus differs post-natal, possibly related to the timing of adipose tissue development and fetal glucocorticoid response to stress.

Enterocolitis causes profound lymphoid depletion in endothelin receptor B- and endothelin 3-null mouse models of Hirschsprung-associated enterocolitis

Potentially life-threatening enterocolitis is the most frequent complication in children with colonic aganglionosis (Hirschsprung disease, HSCR), and little is known about the mechanisms leading to enterocolitis. Splenic lymphopenia has been reported in the Endothelin Receptor B (Ednrb)-null mouse model of HSCR that develops enterocolitis. In this study, we sought to identify molecular mechanisms underlying this immune phenotype. We employed the Ednrb(-/-) mouse, and the knockout of its ligand, Edn3 (Edn3(-/-)). The major finding is that enterocolitis in the Ednrb(-/-) and Edn3(-/-) mice lead to thymic involution, splenic lymphopenia, and suppression of B lymphopoiesis as a consequence of colonic aganglionosis, not an intrinsic Edn3-Ednrb signaling defect directly affecting the lymphoid organs. We showed that adoptive transfer of Ednrb(-/-) marrow repopulated the RAG2-null mice marrow, thymus and spleen without development of enterocolitis. We identified the glucocorticoid corticosterone, as a potential mediator of the immune phenotype. This previously unrecognized pattern of immune abnormalities in mouse is nearly identical to lymphoid depletion in neonatal sepsis during severe physiological stress, suggesting that the mouse model used here could be also used for sepsis studies.

Factors associated with thymic size at birth among low and normal birth-weight infants

OBJECTIVE

To study the effect of gestational and perinatal exposures on thymic size in 366 normal birth weight and 426 low birth weight (LBW) neonates in Guinea-Bissau in West Africa.

STUDY DESIGN

In a cross-sectional study, thymic size was measured at birth by the use of ultrasound. Information on possible determinants was collected from pregnancy cards, hospital records, and interviews with the mother. We used the log-transformed thymic index and thymus/weight index as outcome measures. Data were analyzed with adjusted linear regression models providing geometric mean ratios (GMRs) with 95% CI.

RESULTS

Determinants of thymic size among normal birth weight infants were pathologic amniotic fluid (adjusted GMR for thymic index: 0.84 [0.74-0.96]) and male sex (GMR: 1.13 [1.06-1.22]). Among LBW infants, birth season (1.11 [1.01-1.22]), maternal body temperature (0.89 [0.79-0.98]), antibiotic treatment at the time of labor (0.84 [0.70-1.00]), number of pregnancy consultations (1.03 [1.00-1.05]), maternal age (0.91 [0.84-0.98]), Apgar score (1.06 [1.03-1.10]), and infant convulsions (0.44 [0.29-0.65]) were all independent determinants of thymic index but not all were determinants of thymus/weight index. Pathologic amniotic fluid and cesarean delivery were associated with thymus/weight index among LBW infants (0.85 [0.75-0.95] and 0.80 [0.67-0.96]) but were only borderline significant for thymic index.

CONCLUSION

Exposures mainly related to stress and infections were associated with a smaller thymus, mainly in LBW infants.

Long-term renal consequences of preterm birth

The normal development of the kidney may be affected by several factors, including abnormalities in placental function, resulting in fetal growth restriction, exposure to maternal disease states, including hypertension and diabetes, antenatal steroids, chorioamnionitis, and preterm delivery. After preterm birth, several further insults may occur that may influence nephrogenesis and renal health, including exposure to nephrotoxic medications, postnatal growth failure, and obesity after growth restriction. In this review article, common clinical neonatal scenarios are used to highlight these renal risk factors, and the animal and human evidence on which these risk factors are based are discussed.

Monitoring fetal immune development in human pregnancies: current concepts and future goals

The vast majority of the current knowledge on immune development in the fetal period has been gained from animal studies, particularly from mouse models. This has led to a great improvement in our current understanding of immune ontogeny. However, it has also become clear that in many ways the mouse model of pregnancy differs from the situation in human pregnancy, such as the degree and importance of trophoblast invasion, the kind of MHC class repertoire of the extravillous trophoblast cells, and differences concerning the development and regulation of T-cells. It will be of paramount importance to develop non-invasive screening methods to assess fetal immune development in humans. The focus of this mini-review is to discuss how prenatal ultrasound evaluation can be used as a tool to monitor fetal immune development in human pregnancies. To identify the fetuses at risk of immune disorders could be the first step to developing prevention strategies in the future.

IL-1β and TGF-β weaken the placental barrier through destruction of tight junctions: an in vivo and in vitro study

INTRODUCTION

Chorioamnionitis is a gestational pathological condition characterized by acute inflammation of the amniochorionic membranes and placentas leading to high concentrations of IL-1β, Il-6, Il-8 and TGF-β in the amniotic fluid. In normal conditions, the permeability of foeto-maternal barrier is due to the assembly and maintenance of different cellular junctional domains.

METHODS

In the present study, first we aimed to evaluate the protein expression (by immunohistochemistry and western blotting) and mRNA (by real time PCR) levels of the molecular components of tight junctions (Zonula occludens-1 and occludin), and of adherent junctions (VE-cadherin and β-catenin) in placentas from chorioamnionitis compared to that in normal pregnancies.

RESULTS

Western blotting results showed a significant down-regulation of occludin in placentas affected with chorioamnionitis. No differences were detected for the other proteins analysed. We evaluated whether occludin expression was regulated by IL-1β, IL-6, IL-8 and TGF-β by means of in vitro studies using HUVEC cultures and demonstrated a key role of IL-1β and TGF-β in the disappearance of occludin at cellular border.

CONCLUSIONS

We conclude by suggesting a pivotal role of these two cytokines in facilitating intra-placental infection via para-cellular way due to the disassembly of tight junctions at trophoblastic and endothelial cells in placental tissues.

Processionary Caterpillar Setae and Equine Fetal Loss

Pregnant mares were experimentally exposed to whole caterpillar or exoskeleton of the Processionary caterpillar ( Ochrogaster lunifer) via gavage. Tissues were collected from resulting abortions and near or full-term pregnancies consisting of 13 aborted fetuses, 3 fetuses from treated euthanized mares, membranes of 5 foals, and organs from 3 foals. Three control membranes and 1 control fetus and membranes were examined. Caterpillar setal fragments were present in the allantochorion of the 3 fetuses from the euthanized mares and 11 of 12 aborted fetuses (92%) embedded in the chorion (villi or stroma) or allantois (vasculature or stroma). Placental locations of fragments ranged from the cervical pole region to the body encompassing the umbilical insertion and pregnant horn. Numbers in each fetus ranged from 1 to 7 fragments. Setae were present in the allantochorion from 2 to 22 days after the initial treatment. Acute to chronic active inflammation was present in all aborted fetuses, all euthanized fetuses, and within at least 1 tissue level (chorion, allantois, umbilical cord, or amnion) of the membranes from full-term foals. Amnionitis, funisitis, and allantoitis were present in 95% of the examined membranes. Pneumonia was present in 95% of the specimens, and bacteria were present histologically in 90.5% of the specimens with or without accompanying inflammation. The rapid migration of setae within 2 days after mare exposure suggests that direct setal migration into the fetal membranes is a likely initiating factor for equine amnionitis and fetal loss (EAFL).

Fetal immune response to chorioamnionitis

Chorioamnionitis is a frequent cause of preterm birth and is associated with an increased risk for injury responses in the lung, gastrointestinal tract, brain, and other fetal organs. Chorioamnionitis is a polymicrobial nontraditional infectious disease because the organisms causing chorioamnionitis are generally of low virulence and colonize the amniotic fluid often for extended periods, and the host (mother and the fetus) does not have typical infection-related symptoms such as fever. In this review, we discuss the effects of chorioamnionitis in experimental animal models that mimic the human disease. Our focus is on the immune changes in multiple fetal organs and the pathogenesis of chorioamnionitis-induced injury in different fetal compartments. As chorioamnionitis disproportionately affects preterm infants, we discuss the relevant developmental context for the immune system. We also provide a clinical context for the fetal responses.

Fetal tyhmus size as a predictor of histological chorioamnionitis in preterm premature rupture of membranes

OBJECTIVE

To predict histological chorioamnionitis (CA) in the cases of preterm premature rupture of membranes by using fetal thymus transverse and anteroposterior diameters and areal measurements.

METHODS

Fifty healthy and 50 patients diagnosed with preterm premature rupture of membranes (PPROM) between 24 and 37 weeks of gestation were included in the study. Fetal thymus measurements were done and repeated on a weekly basis until delivery, Furthermore white blood cell, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels were measured every other day until delivery, too. Following delivery, all patients' placentas were sent to pathology.

RESULTS

Histological CA was detected in 48% of the PPROM patients. There were no patients in either group with clinical CA. Thymus transverse diameter had 91% sensitivity, 81% specificity, 82% PPV, and 91% NPV in predicting histological CA in PPROM patients. No linear relationship was found between thymus anteroposterior diameter measurements and gestational age. Thymus area measurements have sensitivity of 75%, specificity of 81%, PPV of 78%, NPV of78% in determining CA in patients with PPROM.

CONCLUSION

Both thymus transverse diameter and area measurement are more significant than sedimentation and CRP values in predicting histological CA. Fetal thymus measurements can be used in early diagnosis of infections among high risk patients.

Blood stream infection is associated with altered heptavalent pneumococcal conjugate vaccine immune responses in very low birth weight infants

OBJECTIVE

Sepsis in older children and adults modifies immune system function. We compared serotype-specific antibody responses to heptavalent pneumococcal conjugate vaccine (PCV7) in very low birth weight infants (<1500 g,VLBWs) with and without blood stream infection (BSI) during their birth hospitalization.

STUDY DESIGN

Retrospective analysis of prospectively collected data for the Neonatal Research Network study of PCV7 responses among VLBWs. Infants received PCV7 at 2, 4 and 6 months after birth with blood drawn 4 to 6 weeks after third dose. Serotype antibodies were compared between infants with or without a history of BSI. Regression models were constructed with BW groups and other confounding factors identified in the primary study.

RESULT

In all, 244 infants completed the vaccine series and had serum antibody available; 82 had BSI. After adjustment, BSI was not associated with reduced odds of serum antibody 0.35 μg ml(-1).

CONCLUSION

BSI was not associated with reduced odds of World Health Organization-defined protective PCV7 responses in VLBWs.

Characterization of the fetal blood transcriptome and proteome in maternal anti-fetal rejection: evidence of a distinct and novel type of human fetal systemic inflammatory response

BACKGROUND

The human fetus is able to mount a systemic inflammatory response when exposed to microorganisms. This stereotypic response has been termed the 'fetal inflammatory response syndrome' (FIRS), defined as an elevation of fetal plasma interleukin-6 (IL-6). FIRS is frequently observed in patients whose preterm deliveries are associated with intra-amniotic infection, acute inflammatory lesions of the placenta, and a high rate of neonatal morbidity. Recently, a novel form of fetal systemic inflammation, characterized by an elevation of fetal plasma CXCL10, has been identified in patients with placental lesions consistent with 'maternal anti-fetal rejection'. These lesions include chronic chorioamnionitis, plasma cell deciduitis, and villitis of unknown etiology. In addition, positivity for human leukocyte antigen (HLA) panel-reactive antibodies (PRA) in maternal sera can also be used to increase the index of suspicion for maternal anti-fetal rejection. The purpose of this study was to determine (i) the frequency of pathologic lesions consistent with maternal anti-fetal rejection in term and spontaneous preterm births; (ii) the fetal serum concentration of CXCL10 in patients with and without evidence of maternal anti-fetal rejection; and (iii) the fetal blood transcriptome and proteome in cases with a fetal inflammatory response associated with maternal anti-fetal rejection.

METHOD OF STUDY

Maternal and fetal sera were obtained from normal term (n = 150) and spontaneous preterm births (n = 150). A fetal inflammatory response associated with maternal anti-fetal rejection was diagnosed when the patients met two or more of the following criteria: (i) presence of chronic placental inflammation; (ii) ≥80% of maternal HLA class I PRA positivity; and (iii) fetal serum CXCL10 concentration >75th percentile. Maternal HLA PRA was analyzed by flow cytometry. The concentrations of fetal CXCL10 and IL-6 were determined by ELISA. Transcriptome analysis was undertaken after the extraction of total RNA from white blood cells with a whole-genome DASL assay. Proteomic analysis of fetal serum was conducted by two-dimensional difference gel electrophoresis. Differential gene expression was considered significant when there was a P < 0.01 and a fold-change >1.5.

RESULTS

(i) The frequency of placental lesions consistent with maternal anti-fetal rejection was higher in patients with preterm deliveries than in those with term deliveries (56% versus 32%; P < 0.001); (ii) patients with spontaneous preterm births had a higher rate of maternal HLA PRA class I positivity than those who delivered at term (50% versus 32%; P = 0.002); (iii) fetuses born to mothers with positive maternal HLA PRA results had a higher median serum CXCL10 concentration than those with negative HLA PRA results (P < 0.001); (iv) the median serum CXCL10 concentration (but not IL-6) was higher in fetuses with placental lesions associated with maternal anti-fetal rejection than those without such lesions (P < 0.001); (v) a whole-genome DASL assay of fetal blood RNA demonstrated differential expression of 128 genes between fetuses with and without lesions associated with maternal anti-fetal rejection; and (vi) comparison of the fetal serum proteome demonstrated 20 proteins whose abundance differed between fetuses with and without lesions associated with maternal anti-fetal rejection.

CONCLUSION

We describe a systemic inflammatory response in human fetuses born to mothers with evidence of maternal anti-fetal rejection. The transcriptome and proteome of this novel type of fetal inflammatory response were different from that of FIRS type I (which is associated with acute infection/inflammation).

Soluble ST2 in the fetal inflammatory response syndrome: in vivo evidence of activation of the anti-inflammatory limb of the immune response

OBJECTIVE

Inflammation is a mechanism of host response to infection, which can be harmful when inappropriately modulated. Soluble ST2 (sST2) is a decoy receptor of interleukin (IL)-33, and this complex modulates the balance in the Th1/Th2 immune response. Moreover, sST2 inhibits the production of pro-inflammatory cytokines in cooperation with an anti-inflammatory cytokine, IL-10. The objectives of this study were to: (1) determine whether umbilical cord plasma sST2 concentration differs between preterm neonates with and without funisitis and between those with and without the fetal inflammatory response syndrome (FIRS); and (2) evaluate the relationship between sST2 and IL-10 among neonates with funisitis and/or FIRS.

METHODS

Umbilical cord plasma was collected from neonates delivered prematurely due to preterm labor or preterm prelabor rupture of membranes with (n = 36), and without funisitis (n = 30). FIRS (umbilical cord IL-6 concentration ≥ 17.5 pg/mL) was identified in 29 neonates. Plasma sST2 and IL-10 concentrations were determined by enzyme linked immune sorbent assay.

RESULTS

The median umbilical cord plasma sST2 concentration was 6.7-fold higher in neonates with FIRS than in those without FIRS (median 44.6 ng/mL, interquartile range (IQR) 13.8-80.3 ng/mL versus median 6.7 ng/mL, IQR 5.6-20.1 ng/mL; p < 0.0001). Similarly, the median umbilical cord plasma sST2 concentration was 2.7-fold higher in neonates with funisitis than in those without funisitis (median 19.1 ng/mL; IQR 7.1-75.0 ng/mL versus median 7.2 ng/mL; IQR 5.9-23.1 ng/mL; p = 0.008). There was a strong positive correlation between sST2 and IL-10 in neonates with funisitis and/or FIRS (Spearman's Rho = 0.7, p < 0.0001).

CONCLUSION

FIRS and funisitis are associated with an elevation of umbilical cord plasma concentrations of soluble ST2. This protein represents an important mediator of the immune response in neonates diagnosed with FIRS by promoting an anti-inflammatory effect in association with IL-10.

Thrown off balance: the effect of antenatal inflammation on the developing lung and immune system

In recent years, translational research with various animal models has been helpful to answer basic questions about the effect of antenatal inflammation on maturation and development of the fetal lung and immune system. The fetal lung and immune systems are very plastic and their development can be conditioned and influenced by both endogenous and/or exogenous factors. Antenatal inflammation can induce pulmonary inflammation, leading to lung injury and remodeling in the fetal lung. Exposure to antenatal inflammation can induce interleukin-1α production, which enhances surfactant protein and lipid synthesis thereby promoting lung maturation. Interleukin-1α is therefore a candidate for the link between lung inflammation and lung maturation, preventing respiratory distress syndrome in preterm infants. Antenatal inflammation can, however, cause structural changes in the fetal lung and affect the expression of growth factors, such as transforming growth factor-beta, connective tissue growth factor, fibroblast growth factor-10, or bone morphogenetic protein-4, which are essential for branching morphogenesis. These alterations cause alveolar and microvascular simplification resembling the histology of bronchopulmonary dysplasia. Antenatal inflammation may also affect neonatal outcome by modulating the responsiveness of the immune system. Lipopolysaccharide-tolerance (endotoxin hyporesponsiveness/immunoparalysis), induced by exposure to inflammation in utero, may prevent fetal lung damage, but increases susceptibility to postnatal infections. Moreover, prenatal exposure to inflammation appears to be a predisposition for the development of adverse neonatal outcomes, like bronchopulmonary dysplasia, if the preterm infant is exposed to a second postnatal hit, such as mechanical ventilation oxygen exposure, infections, or steroids.

Ultrasound measurement of the transverse diameter of the fetal thymus in pregnancies complicated by the preterm prelabor rupture of membranes

PURPOSE

To determine whether the measurement of the transverse diameter of the fetal thymus is of value in the identification of either histologic chorioamnionitis or funisitis in pregnancies complicated by preterm prelabor rupture of membranes (PPROM).

METHODS

The transverse diameter of the fetal thymus was measured in 216 fetuses from PPROM pregnancies. A small thymus was defined as a transverse thymic diameter below the fifth percentile according to a previously published nomogram. The placenta, the fetal membranes, and the umbilical cord were assessed for the presence of inflammation.

RESULTS

A small thymus was identified in 69% (150/216) of fetuses. A small thymus was present in 80% (106/133) and 88% (36/41) of women with histologic chorioamnionitis or funisitis, respectively. The presence of a small thymus had a sensitivity of 79%, specificity of 47%, positive predictive value of 71%, negative predictive value of 59% for the identification of chorioamnionitis (p < 0.0001; odds ratio 3.5) and a sensitivity of 88%, specificity of 35%, positive predictive value of 24%, and negative predictive value of 92% in the identification of funisitis (p = 0.004; odds ratio 4.4).

CONCLUSIONS

The sonographic finding of a small thymus is a sensitive indicator of histologic chorioamnionitis or funisitis; low specificity excludes it as a possible clinical implication in the management of PPROM pregnancies.