Circulating bioactive tumor necrosis factor-alpha, tumor necrosis factor-alpha receptors, fibronectin, and tumor necrosis factor-alpha inducible cell adhesion molecule VCAM-1 in uncomplicated pregnancy

The causal role of intestinal microbiome in development of pre-eclampsia

The correlation of pre-eclampsia (PE) and intestinal microbiome has been widely demonstrated in existing research, whereas their causal relationship has been rarely explored. The causal relationship between intestinal microbiome and PE risk was examined using large-scale genome-wide association studies (GWAS) summary statistics. To be specific, the causal microbial taxa for PE were identified using the two-sample Mendelian randomization (MR) method. The results were verified to be robust through comprehensive sensitive analyses, and the independence of causal relationship was ensured through novel multivariable MR analyses. The possibility of reverse relationships was ruled out through reverse-direction MR analyses. Lastly, the biofunction was explored through enrichment analysis, and a series of validations of PE results in a second GWAS were performed to confirm the results. After correction, four microbial taxa, including Streptococcus genus for PE (FDR q = 0.085), Olsenella genus for PE (FDR q = 0.085), Enterobacteriales order for PE (FDR q = 0.0134), and Akkermansia genus for PE (FDR q = 0.015), had a causal relationship to diverse joint PE (FDR q < 0.15). Moreover, when three different methods were employed on basis of the nominal significance (P < 0.05), five suggestive microbial taxa took on significance. The effect of heterogeneity and horizontal pleiotropy was excluded through sensitive analysis, and the possibility of horizontal pleiotropy of BMI was ruled out through multivariable MR analysis. The protective mechanism of the identified taxa against PE was illustrated through GO enrichment analysis and KEGG pathways. A number of microbial taxa had a causal relationship to PE. The result of this study provides more insights into intestinal microbiome in the pathology of PE.

Placental Regulation of Energy Homeostasis During Human Pregnancy

Successful pregnancies rely on sufficient energy and nutrient supply, which require the mother to metabolically adapt to support fetal needs. The placenta has a critical role in this process, as this specialized organ produces hormones and peptides that regulate fetal and maternal metabolism. The ability for the mother to metabolically adapt to support the fetus depends on maternal prepregnancy health. Two-thirds of pregnancies in the United States involve obese or overweight women at the time of conception. This poses significant risks for the infant and mother by disrupting metabolic changes that would normally occur during pregnancy. Despite well characterized functions of placental hormones, there is scarce knowledge surrounding placental endocrine regulation of maternal metabolic trends in pathological pregnancies. In this review, we discuss current efforts to close this gap of knowledge and highlight areas where more research is needed. As the intrauterine environment predetermines the health and wellbeing of the offspring in later life, adequate metabolic control is essential for a successful pregnancy outcome. Understanding how placental hormones contribute to aberrant metabolic adaptations in pathological pregnancies may unveil disease mechanisms and provide methods for better identification and treatment. Studies discussed in this review were identified through PubMed searches between the years of 1966 to the present. We investigated studies of normal pregnancy and metabolic disorders in pregnancy that focused on energy requirements during pregnancy, endocrine regulation of glucose metabolism and insulin resistance, cholesterol and lipid metabolism, and placental hormone regulation.

Maternal Glucocorticoid Metabolism Across Pregnancy: A Potential Mechanism Underlying Fetal Glucocorticoid Exposure

CONTEXT

Across pregnancy, maternal serum cortisol levels increase up to 3-fold. It is not known whether maternal peripheral cortisol metabolism and clearance change across pregnancy or influence fetal cortisol exposure and development.

OBJECTIVES

The primary study objective was to compare maternal urinary glucocorticoid metabolites, as markers of cortisol metabolism and clearance, between the second and third trimester of pregnancy. Secondary objectives were to test associations of total maternal urinary glucocorticoid excretion, with maternal serum cortisol levels and offspring birth weight z score.

DESIGN, PARTICIPANTS, AND SETTING

A total of 151 women with singleton pregnancies, recruited from prenatal clinic at the Pittsburgh site of the Measurement of Maternal Stress (MOMS) study, had 24-hour urine collections during both the second and third trimesters.

RESULTS

Between the second and third trimester, total urinary glucocorticoid excretion increased (ratio of geometric means [RGM] 1.37, 95% CI 1.22-1.52, P < .001), and there was an increase in calculated 5β-reductase compared to 5α-reductase activity (RGM 3.41, 95% CI 3.04-3.83, P < .001). During the third trimester total urinary glucocorticoid excretion and serum cortisol were negatively correlated (r = -0.179, P = .029). Mean total urinary glucocorticoid excretion across both trimesters and offspring birth weight z score were positively associated (β = 0.314, P = .001).

CONCLUSIONS

The estimated activity of maternal enzymes responsible for cortisol metabolism change between the second and third trimester of pregnancy. Additionally, maternal peripheral metabolism and clearance of cortisol may serve as a novel mechanism affecting fetal cortisol exposure and growth.

Group B streptococcal colonization and the risk of pre-eclampsia

To determine if there was an association between recto-vaginal group B streptococcus (GBS) colonization and pre-eclampsia, two cross-sectional studies were conducted using statewide hospital databases. The first study analysed data from the state of Florida, USA, and included 190 645 women who were discharged in 2001. This dataset was used to generate the hypothesis that GBS colonization is associated with pre-eclampsia. The second study tested the GBS hypothesis using the records of 577 153 women who delivered in 2004 or 2005 in Texas, USA. Adjusted odds ratios (aOR) for the outcome of pre-eclampsia comparing GBS-positive to GBS-negative women were calculated using logistic regression. The aOR for the association between GBS carriage and pre-eclampsia was 0·71 [95% confidence interval (CI) 0·65–0·77] in the Florida dataset. In the Texas dataset, the overall prevalence of GBS carriage was 14·1% while the overall prevalence of pre-eclampsia was 4·0%. GBS carriers were 31% less likely than non-carriers to have pre-eclampsia (aOR 0·69, 95% CI 0·66–0·72) in Texas. In two large statewide analyses, GBS carriage was inversely associated with pre-eclampsia. A sensitivity analysis revealed that misclassification of GBS status is not a likely explanation of our findings.

Maternal circulating TNF-alpha levels are highly correlated with IL-10 levels, but not IL-6 and IL-8 levels, in women with pre-eclampsia

PROBLEM

Several lines of evidence have shown that maternal cytokine levels of tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-6, IL-8, and IL-10 were altered in women with pre-eclampsia (PE) compared to those from normal pregnancies. In this study, we determined whether these cytokine levels are correlated before and after delivery in patients with PE.

METHOD OF STUDY

Venous blood was obtained from 50 women diagnosed with severe PE at the time of admission and 24 hr after delivery. Plasma concentrations for TNF-alpha, IL-6, IL-8, and IL-10 were measured by ELISA.

RESULTS

There were no statistical differences for maternal levels of TNF-alpha, IL-6, IL-8, and IL-10 before and 24 hr postpartum. TNF-alpha and IL-10, but not IL-6 and IL-8, levels were significantly correlated before and 24 hr after delivery: TNF-alpha: y = 19.963 + 0.953*x; r(2) = 0.924; IL-10: y = 10.521 + 1.113*x; r(2) = 0.984, P < 0.001, respectively. Furthermore, TNF-alpha levels were correlated with IL-10 levels, but not with IL-6 and IL-8 levels.

CONCLUSION

The correlation patterns of TNF-alpha with IL-10 and TNF-alpha with IL-6 and IL-8 suggest disparity in functional regulations between these cytokines in maternal circulation in PE.

Maternal serum granulocyte colony-stimulating factor levels and spontaneous preterm birth

OBJECTIVE

Preterm birth (PTB) remains a cause of substantial morbidity with an elusive etiology. Previous studies suggested an association of PTB with elevated serum levels of granulocyte colony-stimulating factor (G-CSF) at 28 weeks gestation. G-CSF, a hematopoietic cytokine, mediates the increase in leukocytes in pregnancy and may play a role in placentation. We evaluated the association between maternal serum G-CSF in the first and second trimesters and PTB.

METHODS

Serum samples collected for the Collaborative Perinatal Project (CPP) from women with normal pregnancy (n = 394) and PTB (n = 31), defined as delivery before 37 weeks gestation, were used to assess G-CSF levels. Linear regression was used to evaluate the relation of G-CSF with gestational age (GA) at birth. Logistic regression, conditional on GA at sample provision, was used to model the association between G-CSF and PTB.

RESULTS

G-CSF was significantly associated with gestational age at birth (p = 0.02). In conditional logistic regression models, G-CSF was significantly associated with PTB, with an adjusted odds ratio (AOR) of 1.52 (95% confidence interval [CI] 1.07, 2.16) per standard deviation (SD) increase.

CONCLUSIONS

Acute effects of G-CSF on PTB have been suggested. In our study we observed an association of higher serum G-CSF levels early in the second trimester with PTB, suggesting PTB as the culmination process beginning early in, if not before, pregnancy.

Cancer and pregnancy share similar mechanisms of immunological escape

BACKGROUND

Despite the fact that trophoblasts and cancer are both immunogenic, they are able to escape from host immunosurveillance, and the precise mechanisms involved in this process are surprisingly similar in both situations.

METHODS

A literature review of studies on immunological changes occurring during normal pregnancy and cancer was performed.

RESULTS

Loss or downregulation of classical HLA antigens as well as the presence of non-classical HLA-G molecules, a Th2 cytokine activity shift, secretion of immunosuppressive factors and blocking antibodies and finally induction of apoptosis in immunocytes seem to be the most effective mechanisms of immunological escape in pregnancy and cancer.

CONCLUSIONS

The process of immunological escape in cancer and pregnancy is based on similar mechanisms.

Do adiponectin, TNFalpha, leptin and CRP relate to insulin resistance in pregnancy? Studies in women with and without gestational diabetes, during and after pregnancy

BACKGROUND

The role of adiponectin, tumour necrosis factor alpha (TNFalpha), leptin and C-reactive protein in the insulin resistance of pregnancy is not clear. We measured their levels in women with gestational diabetes (GDM) and in controls, during and after pregnancy, and related them to insulin secretion and action.

METHODS

Nineteen women with GDM and 19 BMI-matched healthy pregnant women underwent intravenous glucose tolerance tests in the third trimester of pregnancy and 4 months postpartum to determine insulin sensitivity (SI) and insulin secretion. Adiponectin, TNFalpha, leptin and high sensitivity CRP (hsCRP) were measured in fasted blood.

RESULTS

Of the circulating factors, only leptin (r = -0.41, p = 0.01) correlated with SI in pregnancy. Leptin and hsCRP levels were elevated in pregnancy compared to postpartum (leptin (mean +/- SEM): 27.8 +/- 2.4 vs 19.3 +/- 2.1 ng/mL, p < 0.001; hsCRP: 5.2 +/- 0.7 vs 3.2 +/- 0.6 mg/L, p < 0.001). Adiponectin levels did not change from pregnancy to postpartum, despite a marked increase in SI. All four factors correlated with SI postpartum (adiponectin: r = 0.38, p = 0.01; TNFalpha: r = -0.48, p = 0.002; Leptin: r = -0.61, p = 0.001; hsCRP: r = -0.48, p = 0.002). TNFalpha correlated inversely with insulin secretion in pregnancy (r = -0.35, p = 0.03) and was significantly higher in the GDM group (2.62 +/- 0.3 vs 1.88 +/- 0.3 pg/mL, p = 0.01) in pregnancy.

CONCLUSION

In our study, the influence of adiponectin, TNFalpha and hsCRP upon SI is overwhelmed by other factors in pregnancy. While leptin and SI correlated in pregnancy, it is unclear whether this represents cause or effect. Finally, TNFalpha may exert an inhibitory effect on insulin secretion in GDM, contributing to the associated hyperglycaemia.

Th1/Th2 cytokines balance--yin and yang of reproductive immunology

For years conception of Th2 overbalance during pregnancy has been a paradigm for immunology of reproduction, while Th1 activity has been presented as unwanted component. Studies concerning Th1/Th2 balance in physiological and complicated pregnancy have been reviewed. Th1 activity during early peri-implantation period, premature and term labour not only accompanies but even predominates over Th2 activity. Th1 activity plays important role in promotion of Th2 response, regulation of placentation process, defense against infections and initiation of delivery. Together with Th2 activity it is necessary component of immunological reactions during pregnancy, both activities being inseparable like yin and yang. So paradigm of "Th1-Th2 cooperation" is much closer to reality than "Th2 phenomenon".

C-reactive protein and tumor necrosis factor-alpha in gestational hyperglycemia

OBJECTIVES AND STUDY DESIGN

Increasing evidences support an inflammatory origin for gestational hyperglycemia. This paper aims at investigating, cross-sectionally and prospectively, the relationships between tumor necrosis factor-alpha (TNF-alpha) and C-reactive protein (CRP) levels in normoglycemic and hyperglycemic pregnancies of women with and without conventional risk factors for gestational diabetes (GDM).

RESULTS

Both at simple and multiple correlations TNF-alpha levels are associated to fasting insulin, homeostasis model assessment-insulin resistance (HOMA-IR) values and gestational hyperglycemia, while high sensitivity CRP (hsCRP) levels to body mass index (BMI). Furthermore, the TNF-alpha levels of the second trimester and their increments in the third trimester are significant predictors of insulin levels measured at 32-36 weeks in the subgroup of hyperglycemic women with < or = 35 yr, BMI <25 kg/m2 and the absence of a first-degree relative with Type 2 diabetes (respectively, beta=1.1; 95%CI 0.66-1.48; p=0.002 and beta=1.0; 95%CI 0.36-1.66; p=0.02), in a multiple regression model, after multiple adjustments. In a second cohort of women at low risk for GDM (<25 yr, BMI <25 kg/m2 and absence of a first-degree relative with Type 2 diabetes), 24-28 weeks TNF-alpha levels are highly associated with corresponding insulin and HOMA values in the same model (respectively, beta=0.27; 95%CI 0.11-0.43; p=0.001 and beta=0.30; 95%CI 0.14-0.46; p<0.001).

CONCLUSIONS

The data support the developing hypothesis that low-grade systemic inflammation is associated to GDM, in particular for pregnant women without conventional risk factors for gestational hyperglycemia, whose insulin resistance seems less explainable.

Peripheral blood concentrations of adiponectin, an adipocyte-specific plasma protein, in normal pregnancy and preeclampsia

Insulin resistance increases during the normal course of pregnancy, and is considered an important cause of complications including gestational diabetes mellitus, pregnancy-induced hypertension and preeclampsia (PE). Adiponectin, an adipocyte-specific plasma protein, is thought to enhance insulin sensitivity; another adipocytokine, leptin, also is thought to promote insulin sensitivity. We determined peripheral blood concentrations of adiponectin and leptin in 40 healthy nonpregnant women with a body mass index (BMI)<25, 40 healthy pregnant women with prepregnancy BMI<25, and 15 PE patients with prepregnancy BMI<25. Serum adiponectin concentrations were lower in the healthy pregnant group than in the nonpregnant group (9.40+/-4.43 versus 13.15+/-6.69 microg/mL, p<0.01), but difference disappeared after correction for haematocrit. Serum leptin concentrations were high in the normal pregnant group after correction for haematocrit (10.08+/-6.58 versus 6.24+/-3.61 ng/mL, p<0.05). Corrected after haematocrit, serum adiponectin in PE patients was higher than healthy pregnant women at 28 to 40 gestational weeks (17.46+/-11.81 versus 9.33+/-4.47 microg/mL, p<0.01). Leptin in PE was higher than in the normal pregnant group (21.15+/-19.89 versus 11.77+/-6.25 ng/mL, p<0.05), also after correction for haematocrit. These results suggested a metabolic shift in normal pregnant women and PE patients mediated through adipocytokines.

Maternal soluble tumour necrosis factor receptor type 2 (sTNFR2) and adiponectin are both related to blood pressure during gestation and infant's birthweight

OBJECTIVE

Tumour necrosis factor alpha (TNF-alpha) and adiponectin are strongly related to insulin sensitivity; insulin resistance of pregnancy is a major determinant of infant's birthweight. We aimed to study the contributions of maternal serum concentrations of soluble TNF-alpha receptors (sTNFR1 and sTNFR2) and adiponectin to infant's birthweight.

DESIGN

Cross-sectional, hospital-based study of insulin sensitivity during gestation.

PATIENTS

Fifty-one healthy women with uncomplicated pregnancy and delivery (except for elective Caesarian section) and their healthy newborn infants. measurements Maternal blood levels of glucose, insulin, glycosylated haemaglobin (HbA1c), sTNFR1, sTNFR2 and adiponectin at delivery; cord-blood levels of sTNFR1, sTNFR2 and adiponectin.

RESULTS

At delivery, maternal sTNFR2 correlated with systolic blood pressure (SBP; r = 0.38, P = 0.005). In multiple regression analyses, SBP and HbA1c were independent predictors of sTNFR2, explaining 18 and 7% of its variance, respectively; insulin resistance index (HOMA-IR), body mass index at delivery and SBP were independent predictors of adiponectin, explaining 15, 8 and 7% of its variance, respectively. Both maternal sTNFR2 and SBP were negatively correlated with infant's birthweight (r = -0.28, P = 0.04 and r = -0.36, P = 0.01 respectively, adjusted for sex and gestational age). In multivariate regression analyses, infant's sex and either maternal sTNFR2 or adiponectin were independent predictors of infant's birthweight, each explaining between 6 and 9% of birthweight variance. Further addition of maternal SBP to these models revealed that this variable was the main predictor of infant's birthweight, explaining 13% of its variance.

CONCLUSIONS

Maternal sTNFR2 and adiponectin are independently related to both maternal blood pressure and infant's birthweight in uncomplicated pregnancy. The contributions of the TNF-alpha system and adiponectin to hypertensive disorders of pregnancy and fetal growth merit further studies.

Role of tumour necrosis factor-alpha in insulin resistance during normal pregnancy

OBJECTIVE

Role of tumour necrosis factor-alpha (TNF-alpha) was studied in insulin resistance during pregnancy.

STUDY DESIGN

Serum TNF-alpha (ELISA) and fasting C-peptide (Cp) (RIA) concentrations were measured in 40 healthy pregnant women (15, 12 and 13 of them in the 1st, 2nd and 3rd trimesters, respectively) and in 25 healthy non-pregnant women in a case-control study.

RESULTS

TNF-alpha (X+/-S.D.: 5.33+/-0.46 pg/ml) and Cp levels (3.37+/-1.30 ng/ml) were significantly higher in the 3rd trimester as compared with matched healthy controls (TNF: 4.07+/-0.26, Cp: 1.05+/-0.36) and to the pregnant women in 1st (TNF: 4.04+/-0.26, Cp: 1.34+/-0.59) and 2nd (TNF: 4.35+/-0.32, Cp: 1.11+/-0.35) trimesters. Significant positive linear correlation was calculated among TNF-alpha, Cp, Cp/blood glucose ratio (indirect parameters of insulin resistance) and body mass indexes (BMIs) of pregnant women (P<0.01).

CONCLUSION

TNF-alpha may contribute to the insulin resistance during the course of normal pregnancy.

TNF-alpha is a predictor of insulin resistance in human pregnancy

Historically, insulin resistance during pregnancy has been ascribed to increased production of placental hormones and cortisol. The purpose of this study was to test this hypothesis by correlating the longitudinal changes in insulin sensitivity during pregnancy with changes in placental hormones, cortisol, leptin, and tumor necrosis factor (TNF)-alpha. Insulin resistance was assessed in 15 women (5 with gestational diabetes mellitus [GDM] and 10 with normal glucose tolerance) using the euglycemic-hyperinsulinemic clamp procedure, before pregnancy (pregravid) and during early (12-14 weeks) and late (34-36 weeks) gestation. Body composition, plasma TNF-alpha, leptin, cortisol, and reproductive hormones (human chorionic gonadotropin, estradiol, progesterone, human placental lactogen, and prolactin) were measured in conjunction with the clamps. Placental TNF-alpha was measured in vitro using dually perfused human placental cotyledon from five additional subjects. Compared with pregravid, insulin resistance was evident during late pregnancy in all women (12.4 +/- 1.2 vs. 8.1 +/- 0.8 10(-2) mg. kg(-1) fat-free mass. min(-1). microU(-1). ml(-1)). TNF-alpha, leptin, cortisol, all reproductive hormones, and fat mass were increased in late pregnancy (P < 0.001). In vitro, most of the placental TNF-alpha (94%) was released into the maternal circulation; 6% was released to the fetal side. During late pregnancy, TNF-alpha was inversely correlated with insulin sensitivity (r = -0.69, P < 0.006). Furthermore, among all of the hormonal changes measured in this study, the change in TNF-alpha from pregravid to late pregnancy was the only significant predictor of the change in insulin sensitivity (r = -0.60, P < 0.02). The placental reproductive hormones and cortisol did not correlate with insulin sensitivity in late pregnancy. Multivariate stepwise regression analysis revealed that TNF-alpha was the most significant independent predictor of insulin sensitivity (r = -0.67, P < 0.0001), even after adjustment for fat mass by covariance (r = 0.46, P < 0.01). These observations challenge the view that the classical reproductive hormones are the primary mediators of change in insulin sensitivity during gestation and provide the basis for including TNF-alpha in a new paradigm to explain insulin resistance in pregnancy.

Effects of pregnancy and exercise on concentrations of the metabolic markers tumor necrosis factor alpha and leptin

OBJECTIVE

Pregnancy and exercise have opposite effects on fat mass and insulin resistance. We therefore designed this study to test the hypotheses that exercise during pregnancy alters the pregnancy- associated increases in the levels of tumor necrosis factor alpha and leptin and that the changes in tumor necrosis factor alpha and leptin concentrations during pregnancy continue to reflect changes in fat mass.

STUDY DESIGN

The levels of tumor necrosis factor alpha and leptin were measured longitudinally in a control group of physically active women, a group of women who performed endurance exercises >/=4 times a week throughout pregnancy, and a group of women who initially performed endurance exercises but then stopped exercising during midpregnancy. Exercise was monitored, and longitudinal estimates of maternal total mass and fat mass were obtained.

RESULTS

Tumor necrosis factor alpha levels were lower during pregnancy in the women who exercised, and the same was true for leptin levels. When women stopped exercising, however, both tumor necrosis factor alpha and leptin concentrations rose at rates comparable to those seen in the physically active control group. Changes in leptin concentration but not those in tumor necrosis factor alpha concentration correlated with the pregnancy-associated increases in total body and fat mass.

CONCLUSIONS

Regular weight-bearing exercise during pregnancy suppresses the pregnancy-associated changes normally seen in both tumor necrosis factor alpha and leptin. The decrease in leptin reflects decreased fat accretion, and we speculate that the changes in tumor necrosis factor alpha may reflect a change in insulin resistance.