Fetal-placental crosstalk occurs through fetal cytokine synthesis and placental clearance

Distinct cytokine profiles in late pregnancy in Ugandan people with HIV

During pregnancy, multiple immune regulatory mechanisms establish an immune-tolerant environment for the allogeneic fetus, including cellular signals called cytokines that modify immune responses. However, the impact of maternal HIV infection on these responses is incompletely characterized. We analyzed paired maternal and umbilical cord plasma collected during labor from 147 people with HIV taking antiretroviral therapy and 142 HIV-uninfected comparators. Though cytokine concentrations were overall similar between groups, using Partial Least Squares Discriminant Analysis we identified distinct cytokine profiles in each group, driven by higher IL-5 and lower IL-8 and MIP-1α levels in pregnant people with HIV and higher RANTES and E-selectin in HIV-unexposed umbilical cord plasma (P-value < 0.01). Furthermore, maternal RANTES, SDF-α, gro α -KC, IL-6, and IP-10 levels differed significantly by HIV serostatus (P < 0.01). Although global maternal and umbilical cord cytokine profiles differed significantly (P < 0.01), umbilical cord plasma profiles were similar by maternal HIV serostatus. We demonstrate that HIV infection is associated with a distinct maternal plasma cytokine profile which is not transferred across the placenta, indicating a placental role in coordinating local inflammatory response. Furthermore, maternal cytokine profiles in people with HIV suggest an incomplete shift from Th2 to Th1 immune phenotype at the end of pregnancy.

Association of Placental Pathologic Findings with the Severity of Necrotizing Enterocolitis in Preterm infants - A Matched Case-Control Study

OBJECTIVE

To determine the association of placental pathology with the severity of necrotizing enterocolitis (NEC) in preterm infants.

METHODS

This single-center matched case-control study included infants with NEC (n = 107) and gestational age and birth weight-matched controls (n = 130), born between 2013 and 2020. Placentas were evaluated according to the Amsterdam Placental Workshop Group Consensus Statement.

RESULTS

Acute histologic chorioamnionitis with the fetal response was significantly more common in infants with surgical NEC vs. medical NEC (35.4% vs. 15.3%; p = 0.02). On regression model, infants with multiple placental pathologies (OR 2.16; 95% CI 1.01 - 4.73; p = 0.04) and maternal vascular malperfusion (OR 2.2; 95% CI 1.12 - 4.51; p = 0.02) had higher odds of either medical or surgical NEC than controls.

CONCLUSION

Infants with multiple placental lesions, including placental inflammatory and vascular lesions, were at higher risk of medical or surgical NEC in the postnatal period.

Correlation of placental pathology with the postoperative outcomes and white matter injury in preterm infants following necrotizing enterocolitis

BACKGROUND

To determine the association of placental pathologic lesions with postoperative outcomes, survival, and white matter injury (WMI) in preterm infants with NEC.

METHODS

A retrospective chart review of 107 neonates with NEC (Bell stage > IIa) from Jan 2013- June 2020 was completed. Demographic, clinical, and outcome data were compared between infants with or without placental pathologic lesions.

RESULTS

In this cohort, 59/107 (55%) infants had medical NEC, and 48 (45%) had surgical NEC. The infants had a mean gestational age of 28.1±3.7 weeks and a birth weight of 1103±647 g. Maternal vascular malperfusion (82/107, 76.6%) and acute histological chorioamnionitis (42, 39.3%) were the most common pathological placental lesions. Acute histologic chorioamnionitis with fetal inflammatory response was more common in infants with surgical NEC vs. medical NEC (35.4% vs. 15.3%; p = 0.02). The NEC Infants with WMI on brain MRI scans had a significantly higher incidence of acute histological chorioamnionitis (52% vs. 27.8%; P = 0.04). No significant differences in mortality, length of stay and postoperative outcomes in neonates with and without acute histologic chorioamnionitis with fetal inflammatory response were noted. On unadjusted logistic regression, acute histologic chorioamnionitis without fetal inflammatory response was also associated with higher odds of WMI (OR 2.81; 95% CI 1.05-7.54; p = 0.039).

CONCLUSION

Acute histological chorioamnionitis without fetal inflammatory response was associated with higher odds of WMI in infants with NEC, with no significant impact on mortality and other postoperative outcomes.

Placental clearance not synthesis tempers exaggerated pro-inflammatory cytokine response in neonates exposed to chorioamnionitis

BACKGROUND

The source and clearance of cytokines in the fetal circulation in term pregnancies complicated by chorioamnionitis remains unclear as are the contributions of placental transport, synthesis, and clearance. The objectives of the study were to determine (1) fetal and/or placental contributions to synthesis and/or clearance of inflammatory and anti-inflammatory cytokines in term pregnancies complicated by chorioamnionitis and (2) whether this differs in pregnancies further complicated by fetal hypoxia.

METHODS

Prospective cohort study of pregnancies >37 weeks gestational age that included: Group 1, uncomplicated cesarean delivery without labor (n = 20); Group 2, uncomplicated vaginal delivery (n = 30); Group 3, pregnancies complicated by chorioamnionitis (n = 10); Group 4, complicated by chorioamnionitis + fetal hypoxia (n = 10). Umbilical arterial (UmA) and venous (UmV) blood were assayed for IL-1β, IL-2, IL-6, IL-8, TNFα, and IL-10.

RESULTS

IL-6 and IL-8 were below assay detection in UmA and UmV blood in Group 1 and increased in Group 2 (P < 0.01), UmA»UmV (P < 0.01). Their concentrations increased further in Groups 3 and 4 (P = 0.003), UmA»UmV. Placental clearance was concentration dependent that approaches saturation in the presence of chorioamnionitis.

CONCLUSIONS

Marked increases in fetal synthesis of IL-6 and IL-8 occur in chorioamnionitis. Synthesis increase further when complicated by fetal hypoxia. Cytokine removal occurs via placental concentration-dependent mechanisms, potentially contributing to adverse fetal effects.

IMPACT

The source and role of the placenta in synthesis and/or clearance of inflammatory mediators in term pregnancies complicated by clinical chorioamnionitis are unclear; however, conventional wisdom suggests the placenta is their source. This is the first study demonstrating that circulating concentrations of fetal IL-6 and IL-8 in clinical chorioamnionitis ± birth asphyxia in term pregnancies are of fetal origin. Circulating fetal inflammatory cytokines are cleared by concentration-dependent placental mechanisms that are nearly saturated in chorioamnionitis ± fetal hypoxia. These observations provide additional insight into understanding the fetal immune response in term pregnancies complicated by clinical chorioamnionitis.

Birth triggers an inflammatory response in the neonatal periphery and brain

Birth is preceded by inflammation at the fetal/maternal interface. Additionally, the newborn experiences stimuli that under any other circumstance could elicit an immune response. It is unknown, however, whether birth elicits an inflammatory response in the newborn that extends to the brain. Moreover, it is unknown whether birth mode may alter such a response. To study these questions, we first measured corticosterone and pro- and anti-inflammatory cytokines in plasma of mouse offspring at several timepoints spaced closely before and after a vaginal or Cesarean birth. We found highest levels of IL-6 one day before birth and surges in corticosterone and IL-10 just after birth, regardless of birth mode. We next examined the neuroimmune response by measuring cytokine mRNA expression and microglial number and morphology in the paraventricular nucleus of the hypothalamus and hippocampus around the time of birth. We found a marked increase in TNF-α expression in both brain regions a day after birth, and rapid increases in microglial cell number in the first three days postnatal, with subtle differences by birth mode. To test whether the association between birth and cytokine production or expansion of microglia is causal, we manipulated birth timing. Remarkably, advancing birth by a day advanced the increases in all of the markers tested. Thus, birth triggers an immune response in the body and brain of offspring. Our results may provide a mechanism for effects of birth (e.g., acute changes in cell death and neural activation) previously reported in the newborn brain.

A bias away from Th2 in amniotic fluid is involved in preeclampsia

Inflammatory cytokines contribute to the pathophysiology of preeclampsia. However, whether the imbalance of Th1/Th2 cytokines in amniotic fluid is associated with preeclampsia is not well defined. In the present study, we collected peripheral blood and amniotic fluid from normal pregnancy (n = 25) and preeclampsia (n = 22) at last trimester during cesarean section. The Th1/Th2 cytokine levels in amniotic fluid supernatant were detected by a bead-based immunoassay. The percentage of IFN-γ⁺CD4⁺ T cells, TNF-α⁺CD4⁺ T cells, IL-4⁺CD4⁺ T cells and IL-10⁺CD4⁺ T cells in peripheral blood was detected by flow cytometry. We found that in normal pregnancy, the IFN-γ/IL-4 and IFN-γ/IL-5 ratios were decreased in amniotic fluid supernatant compared to that in plasma, indicating a Th2 bias. However, IFN-γ/IL-4 (P = 0.014), IFN-γ/IL-5 (P = 0.005) and IFN-γ/IL-13 (P = 0.047) ratios in amniotic fluid supernatant was significantly increased in preeclampsia patients. The percentage of IFN-γ⁺CD4⁺ T cells (20.70 ± 7.61% vs 16.55 ± 4.96%, P = 0.041) and TNF-α⁺CD4⁺ T cells (31.78 ± 10.66% vs 19.47 ± 13.54%, P = 0.048) was significantly elevated in preeclampsia compared to normal pregnancy. Our finding demonstrates that a shift away from Th2 bias in amniotic fluid and circulating CD4⁺ T cells is involved in the pathogenesis of preeclampsia. This study suggests restoring the Th2 bias in amniotic fluid might be a therapeutic target of preeclampsia.

Placental vascular malperfusion lesions in fetal congenital heart disease

BACKGROUND

Fetuses with congenital heart disease are at increased risk of perinatal morbidity and mortality, which is highly influenced by their prenatal health. Placental function is vital for the health of the fetus, but increased rates of pathologic lesions of the placenta have been observed in pregnancies complicated by fetal congenital heart disease.

OBJECTIVE

This study aimed to determine the prevalence of both gross and histologic placental pathologies in a cohort of pregnancies complicated by fetal congenital heart disease vs healthy controls using the Amsterdam Placental Workshop Group Consensus Statement sampling and definitions of placental lesions.

STUDY DESIGN

This single-center retrospective cohort study included placental examinations from pregnancies diagnosed prenatally with fetal congenital heart disease between 2010 and 2019; moreover, control placentas were collected from pregnancies without maternal or fetal complications. Placentas were sampled and evaluated according to the Amsterdam Placental Workshop Group Consensus Statement and gross and histopathologic diagnoses determined.

RESULTS

Approximately 80% of fetuses diagnosed with congenital heart disease (n=305) had a placental examination for comparison with controls (n=40). Of note, 239 placentas (78%) in the group with fetal congenital heart disease had at least 1 gross or histopathologic lesion compared with 11 placentas (28%) in the control group (P<.01). One-third of placentas complicated by fetal congenital heart disease met the criteria for small for gestational age, and 48% of placentas had one or more chronic lesions, including maternal vascular malperfusion (23% vs 0%; P<.01), villitis of unknown etiology (22% vs 0%; P<.01), fetal vascular malperfusion (20% vs 0%; P<.01), and other chronic lesions (16% vs 0%; P<.01). Acute inflammation was equally present in both the group with fetal congenital heart disease and the control group (28% vs 28%; P=1.00). Although gestational age and birthweight z score were similar between the 2 groups, birth head circumference was 1.5 cm less in pregnancies complicated by fetal congenital heart disease with a significantly lower z score compared with the control group (-0.52±1.22 vs 0.06±0.69; P<.01).

CONCLUSION

Vascular malperfusion lesions and chronic forms of inflammation occur at markedly higher rates in placentas complicated by fetal congenital heart disease, which may contribute to the decreased head circumference at birth. Further work in neuroplacentology is needed to explore connections among cardiac defects, placental vascular malperfusion lesions, and fetal brain development.

Placental pathologic lesions associated with stroke in term neonates

OBJECTIVE

To determine the birth prevalence of perinatal stroke in term born infants at our high-volume delivery center and assess the frequency of both gross and histologic placental pathologies associated with perinatal stroke using the Amsterdam Placental Workshop Group Consensus Statement guidelines and definitions.

STUDY DESIGN

A single-center retrospective cohort study spanning 2010-2020.

RESULTS

There were 129,759 live births at Parkland Hospital during the study period and a total of 18 term born infants leading to a birth prevalence of 1 in 6,829 infants. Perinatal risk factors were found in all but one patient, and 74% presented with seizures. Pathologic placental examination was available in 56% of the cohort and only one patient had normal placental examination. Acute histologic chorioamnionitis was described in five placentas (50%) and an additional two had isolated umbilical and/or chorionic plate vasculitis with or without funisitis compared to a rate of 28% with acute inflammation in a Control group. Chronic inflammation in the form of villitis of unknown etiology was described in three of the acutely inflamed placentas and was high-grade in each of those while none of the placentas from our Control group showed evidence of any chronic lesion.

CONCLUSION

Both acute and chronic placental inflammation are common in perinatal stroke; placental examination should be considered an essential component to the diagnostic workup.

Cytokine signatures of Plasmodium vivax infection during pregnancy and delivery outcomes

Plasmodium vivax malaria is a neglected disease, particularly during pregnancy. Severe vivax malaria is associated with inflammatory responses but in pregnancy immune alterations make it uncertain as to what cytokine signatures predominate, and how the type and quantity of blood immune mediators influence delivery outcomes. We measured the plasma concentrations of a set of thirty-one biomarkers, comprising cytokines, chemokines and growth factors, in 987 plasma samples from a cohort of 572 pregnant women from five malaria-endemic tropical countries and related these concentrations to delivery outcomes (birth weight and hemoglobin levels) and malaria infection. Samples were collected at recruitment (first antenatal visit) and at delivery (periphery, cord and placenta). At recruitment, we found that P. vivax–infected pregnant women had higher plasma concentrations of proinflammatory (IL-6, IL-1β, CCL4, CCL2, CXCL10) and T_H1-related cytokines (mainly IL-12) than uninfected women. This biomarker signature was essentially lost at delivery and was not associated with birth weight nor hemoglobin levels. Antiinflammatory cytokines (IL-10) were positively associated with infection and poor delivery outcomes. CCL11 was the only biomarker to show a negative association with P. vivax infection and its concentration at recruitment was positively associated with hemoglobin levels at delivery. Birth weight was negatively associated with peripheral IL-4 levels at delivery. Our multi-biomarker multicenter study is the first comprehensive one to characterize the immunological signature of P. vivax infection in pregnancy thus far. In conclusion, data show that while T_H1 and pro-inflammatory responses are dominant during P. vivax infection in pregnancy, antiinflammatory cytokines may compensate excessive inflammation avoiding poor delivery outcomes, and skewness toward a T_H2 response may trigger worse delivery outcomes. CCL11, a chemokine largely neglected in the field of malaria, emerges as an important marker of exposure or mediator in this condition.

Cytokine and growth factor plasma concentrations were evaluated in women from five countries endemic for malaria vivax, at different moments and blood compartments during pregnancy. P. vivax infection during pregnancy was associated with a pro-inflammatory and T_H1 response, together with an antiinflammatory response. Nevertheless, at delivery most associations between cytokines and infection were lost. Of note, CCL11/eotaxin, a chemokine not generally analyzed in malaria studies, presented a lower concentration in P. vivax-infected women and a protective association with hemoglobin levels at delivery. Moreover, IL-4 levels had a negative association with birth weight. Data suggest that a compensated inflammatory/antiinflammatory response in P. vivax infection during pregnancy might avoid poor delivery outcomes, while a predominance of T_H2 responses may be detrimental for birth weight. Further research is warranted to unravel the role of CCL11 in malaria infection or exposure.

Influence of a Concurrent Exercise Training Intervention during Pregnancy on Maternal and Arterial and Venous Cord Serum Cytokines: The GESTAFIT Project

The aim of the present study was to analyze the influence of a supervised concurrent exercise-training program, from the 17th gestational week until delivery, on cytokines in maternal (at 17th and 35th gestational week, and at delivery) and arterial and venous cord serum. Fifty-eight Caucasian pregnant women (age: 33.5 ± 4.7 years old, body mass index: 23.6 ± 4.1kg/m²) from the GESTAFIT Project (exercise (n = 37) and control (n = 21) groups) participated in this quasi-experimental study (per-protocol basis). The exercise group followed a 60-min 3 days/week concurrent (aerobic-resistance) exercise-training from the 17th gestational week to delivery. Maternal and arterial and venous cord serum cytokines (fractalkine, interleukin (IL)-1β, IL-6, IL-8, IL-10, interferon (IFN)-γ, and tumor necrosis factor (TNF)-α) were assessed using Luminex xMAP technology. In maternal serum (after adjusting for the baseline values of cytokines), the exercise group decreased TNF-α (from baseline to 35th week, p = 0.02), and increased less IL-1β (from baseline to delivery, p = 0.03) concentrations than controls. When adjusting for other potential confounders, these differences became non-significant. In cord blood, the exercise group showed reduced arterial IL-6 and venous TNF-α (p = 0.03 and p = 0.001, respectively) and higher concentrations of arterial IL-1β (p = 0.03) compared to controls. The application of concurrent exercise-training programs could be a strategy to modulate immune responses in pregnant women and their fetuses. However, future research is needed to better understand the origin and clearance of these cytokines, their role in the maternal-placental-fetus crosstalk, and the influence of exercise interventions on them.

Placental clearance/synthesis of neurobiomarkers GFAP and UCH-L1 in healthy term neonates and those with moderate-severe neonatal encephalopathy

BACKGROUND

Fetal concentrations of GFAP and UCH-L1 are elevated in umbilical arterial (UmA) blood of neonates with birth asphyxia plus neonatal encephalopathy (NE), but their source and role of placental clearance/synthesis is unknown.

METHODS

Prospective cohort study of term neonates to (a) determine UmA and venous (UmV) blood concentrations of GFAP and UCH-L1 in term uncomplicated pregnancies and their placental synthesis and/or clearance and (b) compare UmA concentrations in uncomplicated pregnancies with those complicated by fetal hypoxia-asphyxia+NE. Three term groups were studied: uncomplicated cesarean delivery without labor (Group 1, n = 15), uncomplicated vaginal delivery with labor (Group 2, n = 15), and perinatal hypoxia-asphyxia+NE (Group 3, n = 8).

RESULTS

UmA GFAP concentrations were lower in Group 1 vs. 2 (P = 0.02) and both demonstrated 100% placental clearance. In contrast, UmA and UmV UCH-L1 concentrations were not unaffected by labor. Group 3 UmA GFAP concentrations were 30- and 8-fold higher than Groups 1 and 2, respectively, P = 0.02, whereas UmA UCH-L1 concentrations were similar in all groups.

CONCLUSIONS

UmA GFAP is derived from the fetus, and circulating levels, which are modulated by placental clearance, increase during uncomplicated labor and more so in the presence of fetal hypoxia-asphyxia+NE, providing a better biomarker than UCH-L1 for hypoxia-asphyxia+NE.

Blood cytokine, chemokine and growth factor profiling in a cohort of pregnant women from tropical countries

The immune status of women changes during and after pregnancy, differs between blood compartments at delivery and is affected by environmental factors particularly in tropical areas endemic for multiple infections. We quantified the plasma concentration of a set of thirty-one T_H1, T_H2, T_H17 and regulatory cytokines, pro-inflammatory and anti-inflammatory cytokines and chemokines, and growth factors (altogether biomarkers), in a cohort of 540 pregnant women from five malaria-endemic tropical countries. Samples were collected at recruitment (first antenatal visit), delivery (periphery, cord and placenta) and postpartum, allowing a longitudinal analysis. We found the lowest concentration of biomarkers at recruitment and the highest at postpartum, with few exceptions. Among them, IL-6, HGF and TGF-β had the highest levels at delivery, and even higher concentrations in the placenta compared to peripheral blood. Placental concentrations were generally higher than peripheral, except for eotaxin that was lower. We also compared plasma biomarker concentrations between the tropical cohort and a control group from Spain at delivery, presenting overall higher biomarker levels the tropical cohort, particularly pro-inflammatory cytokines and growth factors. Only IL-6 presented lower levels in the tropical group. Moreover, a principal component analysis of biomarker concentrations at delivery showed that women from Spain grouped more homogenously, and that IL-6 and IL-8 clustered together in the tropical cohort but not in the Spanish one. Plasma cytokine concentrations correlated with Plasmodium antibody levels at postpartum but not during pregnancy. This basal profiling of immune mediators over gestation and in different compartments at delivery is important to subsequently understand response to infections and clinical outcomes in mothers and infants in tropical areas.

Expression of proinflammatory cytokines IL-1β, IL-6 and TNFα in the retained placenta of mares

Retained fetal membranes (RFM) is a prevalent postpartum disease in mares. During parturition, various proinflammatory cytokines are released in the placenta, which further facilitates uterine contractions, expulsion of the fetus and fetal membranes. We hypothesized that an altered inflammatory response in mares results in retained fetal membranes. Samples of the endometrium and the allantochorion were collected from 15 mares with RFM and from 29 control mares within 2 h of foal delivery. Next, the mRNA expression of IL-1β, IL-6 and TNFα proteins was analyzed by Real Time PCR and Western blot. These cytokines were also localized by immunocytochemistry. In mares with RFM, the mRNA expression of IL-1β in the endometrium (p < 0.05) and IL-6 in the allantochorion (p < 0.0001) was higher than in mares that expelled fetal membranes physiologically. Higher expression of IL-6 in the allantochorion was confirmed by Western blot. In contrast, no changes in TNFα mRNA and protein expression were observed between the 2 groups of mares. Moreover, TNFα mRNA was barely detectable. The presence of all studied cytokine proteins in the allantochorion was confirmed by immunocytochemistry. The results suggest that the outbreak of inflammation is involved in the mechanism of placenta release in mares. Increased expression of IL-6 in the allantochorion and IL-1β in the endometrium could reflect a local immune response which leads to the detachment of fetal membranes. The low expression of TNFα mRNA might suggest that this cytokine is not involved in the expulsion of fetal membranes. Further work is needed to determine the exact role and timing of inflammatory activation in fetal membranes during equine parturition.