Cytokines in fetal blood and amniotic fluid in Rh-immunized pregnancies

Therapeutic effects of umbilical cord blood plasma in a rat model of acute ischemic stroke

Umbilical cord blood plasma (UCB-PL) contains various cytokines, growth factors, and immune modulatory factors that regulate the proliferation and function of immune cells and adult stem cells. Despite its therapeutic potential, the effects of UCB-PL treatment in conditions of ischemic brain injury have yet to be investigated. In this study, we demonstrated that both behavioral and structural impairments resulting from ischemic brain injury were significantly prevented/reversed after intravenous administration of UCB-PL relative to the vehicle control. As early as 1-week post-ischemia, an increased number of newborn cells in the subventricular zone and a reduced number of activated microglial cells in the peri-infarct area were observed in the UCB-PL group, suggesting that enhanced neurogenesis and/or the suppression of inflammation may have contributed to functional protection/recovery. Moreover, UCB-PL was more effective than plasma derived from a 65-year-old healthy adult for the treatment of ischemia-related structural and functional deficits, indicating that UCB-PL had greater therapeutic potential. This study provides valuable insights into the development of a safe, effective, and cell-free strategy for the treatment of ischemic brain damage and a much-needed alternative for patients who are ineligible for thrombolytic therapy.

Stillbirth in diabetic pregnancies

Pregnancy in women with pregestational diabetes is associated with high perinatal morbidity and mortality. Stillbirth accounts for the majority of cases with perinatal death. Intrauterine growth restriction, pre-eclampsia, foetal hypoxia and congenital malformations may be contributing factors, but more than 50% of stillbirths are unexplained. Majority of stillbirths are characterised by suboptimal glycaemic control during pregnancy. Foetal hypoxia and cardiac dysfunction secondary to poor glycaemic control are probably the most important pathogenic factors in stillbirths among pregnant diabetic women. There is thus a need for new strategies for improving glycaemic control to near-normal levels throughout pregnancy and for preventing and treating hypertensive disorders in pregnancy. Antenatal surveillance tests including ultrasound examinations of the foetal growth rate, kick counting and non-stress testing of foetal cardiac function are widely used. However, future research should establish better antenatal surveillance tests to identify the infants susceptible to stillbirth before it happens.

Increased fetal plasma and amniotic fluid erythropoietin concentrations: markers of intrauterine hypoxia

Tissue hypoxia is the major stimulus of erythropoietin (EPO) synthesis in fetuses and adults. Since EPO does not cross the placenta and is not stored, fetal plasma and amniotic fluid levels indicate EPO synthesis and elimination. Acutely, the rate and magnitude of the increase in plasma EPO levels correlate with the intensity of hypoxia. Amniotic fluid EPO levels correlate with cord plasma levels in normal and abnormal pregnancies, with fetal plasma EPO levels in humans averaging 2.6 times higher than the corresponding amniotic fluid EPO levels. Recent experimental and clinical studies demonstrate that EPO has neuroprotective effects related to its anti-apoptotic and vascular growth-promoting properties. Although under basal conditions the fetal kidneys are the main site of EPO production, during hypoxia recent experimental data indicate an important role of the placenta. Amniotic fluid EPO levels have been shown to increase exponentially during fetal hypoxia in preeclamptic, diabetic and Rh-immunized pregnancies, to correlate inversely with cord blood pH, pO(2) and base excess and to predict neonatal morbidities and NICU admission. As an indicator of chronic intrauterine hypoxia, fetal EPO measurements have increased our knowledge about the pathogenesis and importance of intrauterine growth restriction, macrosomia, diabetic pregnancy, prolonged pregnancy, meconium staining, fetal hemorrhage, fetal anemia, maternal smoking and alcohol consumption, abnormal fetal heart rate and abnormal Doppler flow patterns. While the clinical utility of fetal amniotic fluid and plasma EPO measurements in the management of high-risk pregnancies and their offspring is promising, adequately powered clinical trials are urgently needed.

The intensity of the fetal inflammatory response in intraamniotic inflammation with and without microbial invasion of the amniotic cavity

OBJECTIVE

Intraamniotic inflammation is a risk factor for adverse pregnancy and neonatal outcome, regardless of the presence or absence of a positive amniotic fluid (AF) culture. The purpose of this study was to determine whether the intensity of a fetal inflammatory response (FIR) differs between cases of intraamniotic inflammation with microbiologically proven infection and cases with negative AF cultures.

STUDY DESIGN

The FIR was examined in 89 cases of women with preterm premature rupture of membranes who delivered singleton preterm newborn infants within 48 hours of amniocentesis. AF was cultured for aerobic and anaerobic bacteria and for genital mycoplasmas. AF white blood cell (WBC) count and matrix metalloproteinase-8 (MMP-8) determinations were performed to assess the presence of intraamniotic inflammation. Intraamniotic inflammation was defined as an elevated AF MMP-8 concentration (>23 ng/mL). The intensity of the FIR was determined by the umbilical cord plasma concentrations of C-reactive protein (CRP). Patients were divided into 3 groups according to the presence or absence of intraamniotic inflammation and AF culture results: group 1, without intraamniotic inflammation and with a negative AF culture (n = 28); group 2, with intraamniotic inflammation and with a negative AF culture (n = 26); group 3, with a positive AF culture (n = 35).

RESULTS

Neonates who were born to mothers with intraamniotic inflammation and negative AF cultures had a significantly higher median umbilical cord plasma CRP concentration than did those without intraamniotic inflammation and a negative AF culture (P < .005) but a significantly lower median cord plasma CRP concentration than did those with proven AF infection (P < .05). Patients with intraamniotic inflammation and a negative AF culture had significantly higher median AF MMP-8 concentrations and WBC count than did those without intraamniotic inflammation and a negative AF culture (P < .001). However, there was no significant difference in the median AF MMP-8 and WBC count between patients with intraamniotic inflammation and a negative AF culture and those with proven AF infection (MMP-8, P > .1, and WBC, P = .09).

CONCLUSION

Intraamniotic inflammation without documented AF infection is a risk factor for a systemic FIR. However, the magnitude of the FIR in those cases was lower than in those with documented AF infection.

Leukocyte numbers correlate with plasma levels of granulocyte-macrophage colony-stimulating factor in sickle cell disease

Despite a clear role for leukocytes in modulating the pathophysiology of sickle cell disease (SCD), the mechanism by which leukocyte numbers are increased in this disorder remains unclear. Hypothesizing that the chronic inflammatory state, elicited by adhesive interactions involving various cell types, might underlie leukocytosis, we measured plasma levels of proinflammatory or myeloid cytokines that play a role in leukocytosis and examined their correlations with leukocyte numbers in patients with SCD. Our studies found that, although plasma levels of granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 3, and macrophage colony-stimulating factor are elevated in steady-state patients with SCD, only plasma GM-CSF levels are positively correlated with the numbers of total leukocytes, neutrophils, monocytes, and eosinophils, regardless of whether they received hydroxyurea. GM-CSF levels were significantly decreased in patients on hydroxyurea therapy. These data suggest a role of GM-CSF in leukocytosis of SCD. In contrast, plasma levels of granulocyte colony-stimulating factor, a major cytokine that induces leukocytosis due to bacterial infection, were lower than those of control subjects. These results indicate that elevated GM-CSF levels may contribute, at least in part, to high leukocyte numbers in SCD. As plasma GM-CSF levels were decreased in patients on hydroxyurea therapy, hydroxyurea may decrease leukocyte numbers by reducing circulating GM-CSF levels.

Sources of amniotic fluid erythropoietin during normoxia and hypoxia in fetal sheep

OBJECTIVE

Erythropoietin is present in human amniotic fluid and has been suggested as a marker of fetal hypoxia. The objectives of the present study were to determine whether erythropoietin is present in ovine amniotic fluid, fetal urine, and/or lung liquid and whether concentrations in these compartments change in parallel with endogenous fetal plasma erythropoietin concentration when the latter is increased experimentally.

STUDY DESIGN

In late gestation chronically catheterized fetal sheep, samples of amniotic fluid and plasma, urine and plasma, lung liquid, amniotic fluid, and plasma were collected before and up to 7 days after induction of 4 types of fetal hypoxia: (1) acute anemic hypoxia that was induced by a single fetal hemorrhage, (2) progressive anemic hypoxia that was induced by daily exchange transfusion, (3) acute hypoxic hypoxia that was induced by the reduction of maternal inspired oxygen content, or (4) chronic placental insufficiency that was induced by daily umbilicoplacental embolization for 4 days. Erythropoietin concentrations were determined by radioimmunoassay. Statistical testing included analysis of variance and least squares regression.

RESULTS

Under basal, nonhypoxic conditions, amniotic fluid erythropoietin concentration averaged 33.2% +/- 1.6% (SE) of fetal plasma erythropoietin concentration, and basal fetal urine and lung liquid erythropoietin concentrations ranged from low (<10% of plasma concentration) to nondetectable. Unlike the strong correlation in humans, basal amniotic fluid and plasma erythropoietin concentrations were correlated only weakly (r = 0.259; r2 = 6.7%; P = .0027; n = 132). Amniotic fluid erythropoietin concentration approximately doubled after 12 hours of severe hypoxic hypoxia or after 24 hours of embolization-induced severe hypoxia but was unchanged after 12 hours of mild-moderate hypoxic hypoxia or 24 hours of anemic hypoxia. Concomitant fetal plasma erythropoietin concentrations increased to 28.1 +/- 5.3, 12.5 +/- 2.7, 10.8 +/- 4.6, and 10.0 +/- 1.3 times basal values, respectively. During progressive fetal anemia, urinary erythropoietin concentration increased almost 10-fold (P = .0023) but remained a small fraction (3.7% +/- 0.4%) of plasma concentration; at 12 hours of hypoxic hypoxia, lung liquid erythropoietin concentration did not vary with the severity of the hypoxia and remained low relative to plasma concentration (4.2% +/- 2.1%).

CONCLUSION

Erythropoietin is present in ovine amniotic fluid, urine, and lung liquid. With only 3 potential sources, the fetal membranes appear to be the primary source of amniotic fluid erythropoietin in the nonhypoxic ovine fetus because basal urine and lung liquid erythropoietin concentrations are much lower than amniotic fluid concentrations. Although unchanged during mild-to-moderate fetal hypoxia, amniotic fluid erythropoietin concentration increases modestly during severe fetal hypoxia. In sheep, fetal urinary erythropoietin may contribute to this rise in amniotic fluid erythropoietin concentration during severe hypoxia, because fetal urinary and plasma concentrations increase in parallel during anemia.

High amniotic fluid erythropoietin levels are associated with an increased frequency of fetal and neonatal morbidity in type 1 diabetic pregnancies

AIMS/HYPOTHESIS

In this study we investigated whether chronic fetal hypoxia, as indicated by amniotic fluid erythropoietin levels, is associated with perinatal morbidity in type 1 diabetic pregnancies.

METHODS

A total of 331 women with type 1 diabetes had at least one childbirth between 1995 and 2000. The amniotic fluid erythropoietin concentration was measured in 156 diabetic singleton pregnancies at a median time of 1 day before Caesarean section without labour contractions and in 19 healthy control subjects at Caesarean section.

RESULTS

The median amniotic fluid erythropoietin level was 14.0 mU/ml (range 2.0-1975.0) in diabetic pregnancies and 6.3 mU/ml (range 1.7-13.7) in controls (p<0.0001). Of the 156 diabetic patients, 21 (13.5%) had amniotic fluid erythropoietin levels higher than 63.0 mU/ml. Amniotic fluid erythropoietin levels correlated negatively with umbilical artery pH (r=-0.49, p<0.0001) and pO2 (r=-0.62, p<0.0001) at birth and neonatal lowest blood glucose level (r=-0.47, p<0.0001). Positive correlations were found between amniotic fluid erythropoietin levels and umbilical artery pCO2 (r=0.49, p<0.0001) and last maternal HbA1c (r=0.43, p<0.0001). Furthermore, a U-shaped correlation was demonstrated between amniotic fluid erythropoietin levels and birthweight z score (z score below -0.6 SD units: r=-0.63, p=0.0007; z score above +1.0 SD units: r=0.32, p=0.0014). Neonatal hypoglycaemia, hypertrophic cardiomyopathy and admission to the neonatal intensive care unit occurred significantly more often in cases with high amniotic fluid erythropoietin levels (>63.0 mU/ml) than in those with normal levels. Multivariate logistic regression analysis revealed that amniotic fluid erythropoietin was the only variable independently related to low umbilical artery pH (<7.21; p<0.0001) and neonatal hypoglycaemia (p=0.002). Low umbilical artery pO2 (<15.0 mm Hg) was explained by amniotic fluid erythropoietin (p<0.0001) and birthweight z score (p=0.004).

CONCLUSIONS/INTERPRETATION

Antenatal high amniotic fluid erythropoietin levels can identify type 1 diabetic pregnancies at increased risk of severe perinatal complications.

Amniotic fluid and cord plasma erythropoietin levels in pregnancies complicated by preeclampsia, pregnancy-induced hypertension and chronic hypertension

AIMS

The purpose of the present study was to compare fetal and neonatal outcomes with amniotic fluid erythropoietin (EPO) levels obtained in the antepartum period in pregnancies complicated by preeclampsia, pregnancy-induced hypertension or chronic hypertension.

METHODS

Erythropoietin concentrations were measured in amniotic fluid within 2 days before delivery and in cord blood at birth in 75 hypertensive women and in 23 healthy controls delivered by cesarean section before labor contractions. Erythropoietin levels did not influence clinical decisions.

RESULTS

Amniotic fluid erythropoietin levels correlated highly significantly with cord plasma EPO levels and were significantly higher in pregnancies complicated by hypertension than in control pregnancies. Umbilical arterial pH, acid-base and blood gas values at birth were not different from controls. Both cord plasma and amniotic fluid erythropoietin levels correlated with cord blood pH, acid-base and blood gas values at birth in the study group. Newborn infants admitted to the newborn intensive care unit had significantly higher fetal erythropoietin levels and were more acidotic, hypoxemic and hypoglycemic than infants admitted to the normal care nursery.

CONCLUSIONS

Our findings suggest that elevated amniotic fluid erythropoietin levels are markers of chronic or subchronic fetal hypoxia and are associated with neonatal morbidity in pregnancies complicated by hypertension.

Oxygen-dependent and tissue-specific regulation of erythropoietin gene expression

Hypoxia-inducible expression of the gene encoding for the glycoprotein hormone erythropoietin (EPO) is the paradigm of oxygen-regulated gene expression. EPO is the main regulator of red blood cell production and more than 100 years of research on the regulation of EPO production have led to the identification of a widespread cellular oxygen sensing mechanism. Central to this signaling cascade is the transcription factor complex hypoxia-inducible factor-1 (HIF-1). Meanwhile, it is known that HIF-1 controls more than 50 oxygen-dependent genes and is now recognized as the main regulator of oxygen homoeostasis in the body. In addition to hypoxic induction, expression of the EPO gene is tightly regulated in a tissue-specific manner. During ontogeny, production of EPO required for erythropoiesis is switched from the fetal liver to the kidneys. Here EPO is mainly synthesized in adulthood. Production of EPO has also been found in organs where it has nonerythropoietic functions: EPO is important for development of the brain and is neuroprotective, whereas it stimulates angiogenesis in the reproductive tract and possibly in other organs. Understanding oxygen and tissue-specific regulation of EPO production is of high relevance for physiology. Moreover, this knowledge might be useful for new therapies to treat human diseases.

Teratogenic alleles and neurodevelopmental disorders

The genetic interaction between mother and fetus during pregnancy is discussed, focusing on teratogenic alleles that act in the mother to alter fetal development and contribute to a neurodevelopmental disorder. For these alleles, the mother is the genetic patient. Teratogenic alleles interact with modifying and specificity alleles that act in the fetus and with environmental factors. Based on examples of the model, two candidate mechanisms emerge as contributors to neurodevelopmental disorders, folate-homocysteine pathways and immune/inflammatory mechanisms. Both, acting in mothers, affect fetal development and contain many polymorphic genes. These two systems interact with each other. Common functional polymorphisms of mild effect in these two systems of interacting genes are good candidates for teratogenic alleles. The presence of teratogenic alleles complicates gene identification for neurodevelopmental disorders. However, using the special methods required to identify teratogenic alleles is important because this could lead to new approaches to prevention and improved therapy of these disorders.

Cord blood serum affects T cells ability to produce and respond to IL-2

The current literature suggests that cord blood (CB) cells are functionally immature. We previously reported that CB sera inhibit T cell proliferation and suggested that the microenvironment in which CB T cells reside may be, in part, responsible for their reduced function. In this study we have tried to explain some of the actions of the CB sera on peripheral blood mononuclear cells (PBMC). We showed that, as expected CB sera decreased the anti-CD3 and anti-CD28-induced proliferative response of PBMC (p < 0.01) but unexpectedly, increased the interleukin-2 (IL-2) specific proliferation of both a human T cell line (p < 0.005) and T cells within a mononuclear cell population (p < 0.05). These findings prompted us to analyse the effect of CB sera on the T cell ability to make and respond to IL-2. Stimulation of T cells in the presence of CB sera increased the frequency of IL-2 producing cells (p < 0.005) (but not the amount of IL-2 secreted) and resulted in a higher expression of CD25 (p < 0.05). Furthermore CB sera (in the presence and absence of IL-2) made the cells apoptose less (p < 0.005) than adult sera. Our results go some way to explaining the effect of the CB microenvironment on CB cellular function.

Fetuses from preeclamptic mothers show reduced hepatic erythropoiesis

The fetal liver is the main hematopoietic organ during intrauterine life. Morphometrical studies were performed on liver sections to detect changes occurring with intrauterine growth retardation and preeclampsia. Compared with the controls (n = 10), fetuses from preeclamptic mothers showed a severe reduction of erythroid cells by 60% on average (n = 18). Closer examination revealed that the erythroid cells at early stages of differentiation were more affected (80% reduction) than at later stages (55%). Seven out of 18 fetuses from preeclamptic mothers did not show growth retardation but exhibited severely reduced hepatic erythropoiesis. We suggest that the prime factor for impaired red blood cell production is preeclampsia itself rather than intrauterine growth retardation. Regulation of erythropoiesis in utero might depend on the interaction of many hematopoietic growth factors, and preeclampsia might alter the balance. To test this notion, we quantitated erythropoietin in fetal blood and various cytokines in the amniotic fluid. An elevation of erythropoietin and interleukin (IL)-3 levels was seen in babies born under the conditions of preeclampsia, whereas the concentrations of granulocyte/macrophage-colony-stimulating factor (CSF), granulocyte-CSF, and IL-1 beta were reduced, and the levels of IL-6 and IL-8 remained constant. With preeclampsia, a discrepancy between elevation of erythrocyte numbers in peripheral blood and depression of hematopoiesis at the main production site, the fetal liver, is seen. Concomitantly, there is elevation of some but reduction of other hematopoietic cytokines. We envision that during the course of preeclampsia quantitation of hematopoietic growth factors might allow to predict the deterioration of in utero life conditions.