Michael Permezel

Nuclear Factor Kappa B Regulation of Proinflammatory Cytokines in Human Gestational Tissues In Vitro

Abstract Proinflammatory cytokines are implicated in the initiation and progression of human labor and delivery, particularly in relation to infection-induced preterm labor. In nongestational tissues, the nuclear factor kappa B (NF-κB) transcription pathway is a key regulator of proinflammatory cytokine release. In these tissues, sulfasalazine (SASP), through its ability to inhibit NF-κB activation, inhibits release of interleukin (IL)-2, IL-12, and tumor necrosis factor (TNF)-α. Therefore, the aim of this study was to investigate whether or not NF-κB activation regulates the formation of proinflammatory cytokines in human gestational tissues. Human placenta, amnion, and choriodecidua (n = 9 separate placentas) were incubated with 10 μg/ml of lipopolysaccharide (LPS) in the absence (control) or presence of SASP (0.1, 1, 5, or 10 mM). After 6 h of incubation, the tissues were collected, and NF-κB DNA binding activity in nuclear extracts was assessed by electromobility shift binding assay. The incubation medium was collected and the release of IL-6, IL-8, and TNF-α was quantified by ELISA. Treatment of placenta, amnion, and choriodecidua with SASP at concentrations 5 mM or greater significantly inhibited the release of IL-6, IL-8, and TNF-α, and NF-κB activation (ANOVA, P < 0.05). The data presented in this study demonstrate that the NF-κB transcription pathway is a key regulator of LPS-stimulated IL-6, IL-8, and TNF-α release from human gestational tissues. The control of NF-κB activation may therefore provide an alternative therapeutic strategy for reducing the release of proinflammatory mediators in infection associated preterm labor.

Gestational Diabetes Mellitus: Clinical Predictors and Long-Term Risk of Developing Type 2 Diabetes A retrospective cohort study using survival analysis

OBJECTIVE—We sought to determine the long-term risk of type 2 diabetes following a pregnancy complicated by gestational diabetes mellitus (GDM) and assess what maternal antepartum, postpartum, and neonatal factors are predictive of later development of type 2 diabetes. RESEARCH DESIGN AND METHODS—This was a retrospective cohort study using survival analysis on 5,470 GDM patients and 783 control subjects who presented for postnatal follow-up at the Mercy Hospital for Women between 1971 and 2003. RESULTS—Risk of developing diabetes increased with time of follow-up for both groups and was 9.6 times greater for patients with GDM. The cumulative risk of developing type 2 diabetes for the GDM patients was 25.8% at 15 years postdiagnosis. Predictive factors for the development of type 2 diabetes were use of insulin (hazard ratio 3.5), Asian origin compared with Caucasian (2.1), and 1-h blood glucose (1.3 for every 1 mmol increase above 10.1 mmol). BMI was associated with an increased risk of developing type 2 diabetes but did not meet the assumption of proportional hazards required for valid inference when using Cox proportional hazards. CONCLUSIONS—While specific predictive factors for the later development of type 2 diabetes can be identified in the index pregnancy, women with a history of GDM, as a group, are worthy of long-term follow-up to ameliorate their excess cardiovascular risk.

Altered Placental Oxidative Stress Status in Gestational Diabetes Mellitus

Oxidative stress has been clearly linked to type 2 diabetes mellitus, however, limited data are available on the involvement of oxidative stress in gestational diabetes mellitus (GDM), a disease of similar pathophysiology. The aim of this study was to investigate the status of placental oxidative stress in healthy pregnant women and women with GDM. The hypothesis to be tested was that tissue markers of oxidative stress are significantly increased in GDM compared to normal placental tissues. Markers of oxidative stress measured were the release of 8-isoprostane (8-epi-prostaglandin F(2alpha)) from human term placental explants (n=11), the activity of the antioxidant enzymes superoxide dismutase and glutathione peroxidase (n=10), and protein carbonyl content (n=12). Placental release of 8-isoprostane was 2-fold greater from women with GDM (P<0.001) compared to healthy pregnant women. Superoxide dismutase activity and protein carbonyl content were elevated in placentae obtained from women with GDM (P<0.04 and P<0.004 respectively), whilst there was no significant difference in the activity of glutathione peroxidase. These data demonstrate the presence of oxidative stress in the placenta from women with GDM, in addition to the induction of a key antioxidant, collectively indicating a state of existing oxidative stress in this condition.

The Role of Oxytocin in Mother-Infant Relations: A Systematic Review of Human Studies

Background: Oxytocin is associated with the establishment and quality of maternal behavior in animal models. Parallel investigations in humans are now under way. This article reviews the current research examining the role of oxytocin in mother‐infant relations, attachment, and bonding in humans. Methods: A systematic search was made of three electronic databases and other bibliographic sources for published research studies that examined oxytocin and mother‐infant relations in humans, including attachment, maternal behavior, parenting, and mother‐infant relations. Results: Eight studies were identified, all of which were unique in their methodologies, populations studied, and measures used. Seven studies found significant and strong associations between levels or patterns of oxytocin and aspects of mother‐infant relations or attachment. Conclusions: Oxytocin appears to be of crucial importance for understanding mother‐infant relationships. The findings of this review suggest that the pioneering, but preliminary, research undertaken to date is promising and that replication with larger samples is needed. Research that draws on more robust measures of attachment and bonding, as well as improved measures of oxytocin that include both central and peripheral levels, will elucidate the role of oxytocin in human mother‐infant relationships. As the production of oxytocin is by no means restricted to mothers, the extension of the oxytocin studies to fathering, as well as to alloparental caregiving, would be an intriguing next step.

Defective insulin signaling in placenta from pregnancies complicated by gestational diabetes mellitus

OBJECTIVE Studies in adipose tissue and skeletal muscle suggest that impaired insulin action is due to defects in the insulin signaling pathway and may play a role in the pathophysiology of insulin resistance associated with gestational diabetes mellitus (GDM) and obesity. The present study tested the hypothesis that endogenous expression levels in the human term placenta of insulin signaling components are altered in placental tissue from GDM women in comparison with normal controls and maternal obesity. DESIGN AND METHODS Placental tissue was collected from normal, diet-controlled GDM, and insulin-controlled GDM in both non-obese and obese women (n=6-7 per group). Western blotting and quantitative RT-PCR was performed to determine the level of expression in the insulin signaling pathway. RESULTS There was a significant increase in insulin receptor (IR) substrate (IRS)-1 protein expression with a concurrent decrease in IRS-2 protein expression in non-obese women with insulin-controlled GDM compared with diet-controlled GDM and normal controls. Furthermore, a decrease in both protein and mRNA expression of phosphatidyl-inositol-3-kinase (PI3-K) p85alpha and glucose transporter (GLUT)-4 was observed in non-obese and obese women with insulin controlled GDM compared with normal controls. When comparing non-obese to obese patients, significant decreases in mRNA expression of IR-beta, PI3K p85alpha and GLUT-4 was found in obese patients. CONCLUSION Our results suggest that post receptor defects are present in the insulin signaling pathway in placenta of women with pregnancies complicated by diabetes and obesity. In addition, expression studies demonstrate post receptor alterations in insulin signaling possibly under selective maternal regulation and not fetal regulation.

SIRT1 Is a Novel Regulator of Key Pathways of Human Labor

Human sirtuin (SIRT) 1 and SIRT2, which possess nicotinamide adenosine dinucleotide (NAD+)-dependent deacetylase activity, exhibit anti-inflammatory actions. However, there are no data available on SIRT1 and SIRT2 expression and regulation in human intrauterine tissues. Thus, the aim of this study was to characterize the localization and expression of SIRT1 and SIRT2 in 1) placenta and fetal membranes before and after term spontaneous labor onset, 2) prelabor fetal membranes from the supracervical site (SCS) and a distal site (DS), and 3) in response to proinflammatory stimuli. Further, the effect of SIRT activation using resveratrol and SRT1720 on prolabor mediators was also assessed. SIRT1 and SIRT2 were localized in the syncytiotrophoblast layer and the cytotrophoblasts of the placenta, amnion epithelium, trophoblast layer of the chorion, and decidual cells. Additionally, SIRT2 was found within the endothelial walls of placental vessels. SIRT2, but not SIRT1, staining was significantly lower in amnion and chorion obtained from the SCS compared to a DS. On the other hand, SIRT1, but not SIRT2, gene and/or protein expression was significantly lower in placenta, amnion, and chorion obtained after labor compared to prelabor. SIRT1 expression, but not SIRT2, was down-regulated by lipopolysaccharide (LPS) and proinflammatory cytokines TNF and IL1B. The SIRT1 activators resveratrol and SRT1720 significantly decreased LPS-induced TNF, IL6, and IL8 gene expression and release and PTGS2 mRNA expression and resultant prostaglandin (PG) E2 and PGF2α release from human gestational tissues. In conclusion, SIRT1 possesses anti-inflammatory actions and thus may play a role in regulating pregnancy and parturition.

Peroxisome proliferator-activated receptors are altered in pathologies of the human placenta: Gestational diabetes mellitus, intrauterine growth restriction and preeclampsia

BACKGROUND Common complications of pregnancy arise in part from dysfunctional placental development, and include gestational diabetes mellitus (GDM), intrauterine growth restriction (IUGR) and preeclampsia (PE). Peroxisome proliferator-activated receptors (PPARs), and their partner retinoid X receptor a (RXRalpha), mediate trophoblast differentiation and thus may offer insight into the pathophysiology of these diseases. METHODS Human placentae were obtained from women at term with GDM and were compared to uncomplicated term placentae. Placentae from women who delivered preterm with IUGR, PE or co-existing PE and IUGR were compared to matched controls. Quantitative RT-PCR and Western blotting were used to examine mRNA and protein expression of PPARalpha, PPARdelta, PPARgamma and RXRalpha. DNA binding activity of PPAR isoforms were measured in nuclear protein extracts. RESULTS GDM was associated with significantly lower placental PPARgamma mRNA and protein, PPARalpha protein and RXRalpha protein expression, while PPAR DNA binding activity remained unchanged. Placentae from women with PE did not demonstrate any changes in mRNA or protein expression or PPAR DNA binding activity, while IUGR/PE placenta showed significant increases in PPARalpha protein, PPARgamma mRNA and protein and RXRalpha mRNA and protein expression. Significantly elevated protein expression of PPARalpha and RXRalpha were associated with IUGR placentae. IUGR and IUGR/PE placentae had significantly higher PPARgamma DNA binding activity compared to controls. CONCLUSIONS The data presented herein suggest that PPARs may be involved in the pathophysiology of GDM, PE and IUGR.

Diabetes and obesity during pregnancy alter insulin signalling and glucose transporter expression in maternal skeletal muscle and subcutaneous adipose tissue.

Severe insulin resistance is a defining attribute of gestational diabetes mellitus (GDM). It is postulated that alterations in the insulin-signalling pathway and subsequent glucose disposal are the underlying cause of insulin resistance in patients with GDM. The purpose of this study was to profile the insulin-signalling pathway and intermediates in insulin-sensitive tissues. Subcutaneous adipose tissue and skeletal muscle were collected from normal glucose-tolerant (NGT) and insulin-controlled GDM in both non-obese and obese cohorts (n=6-8 per subgroup). Expression studies of the insulin-signalling pathway were performed using western blotting and quantitative reverse transcription-PCR. This study demonstrated altered mRNA expression of insulin receptor substrate (IRS)-1, IRS-2, glucose transporter (GLUT)-1, GLUT-4 and glycogen synthase kinase (GSK)-3 isoforms genes in adipose tissue in GDM women in comparison to NGT pregnant controls. In skeletal muscle, insulin-controlled GDM was associated with decreased IRS-1, phosphatidylinositol-3-kinase (PI3-K) p85alpha, GLUT-1 and -4, GSK-3 isoforms and phosphoinositide-dependent kinase-1. Both adipose tissue and skeletal muscle from women with GDM displayed decreased IRS-1 and GLUT-4 and increased PI3-K p85alpha protein expression. Both skeletal muscle and adipose tissue from obese women demonstrated lower GLUT-1 and -4 mRNA expression and diminished GLUT-4 protein expression in skeletal muscle only. Collectively, our results suggest that diabetes and obesity during pregnancy cause defects in insulin-signalling transduction in adipose tissue and skeletal muscle and may be the underlying cause of GDM.

A Trial of Simple versus Intensified Dietary Modification for Prevention of Progression to Diabetes Mellitus in Women with Impaired Glucose Tolerance

Summary: Women with impaired glucose tolerance are at high risk of developing noninsulin dependent diabetes mellitus (NIDDM). The Mercy Hospital for Women has a long‐term follow‐up programme for women with gestational diabetes, which identifies many women with impaired glucose tolerance. Two hundred of these women were entered into a randomized controlled trial of intensive versus routine dietary advice. Seven women were lost to follow‐up. The annual incidence rates of diabetes mellitus for the 2 groups were 6.1% (intervention) and 7.3% (control), an incident rate ratio of 0.83, 95% confidence interval 0.47–1.48, p = 0.50. Overall, there was a return to normal glucose tolerance in 44% of patients. Multivariate analysis showed that body mass index, fasting and 2‐hour plasma glucose levels at trial entry were significantly associated with an increased risk of diabetes mellitus. Impaired glucose tolerance is an important condition that should be treated with advice about lifestyle modification (diet and/or exercise). We consider that future trials in the management of women with previous gestational diabetes who have impaired glucose tolerance should investigate the effect of pharmacological intervention in addition to diet and/or exercise, the latter providing a therapy that it would be unethical to exclude on the evidence presently available.

The utility of neonatal dried blood spots for the assessment of neonatal vitamin D status

Evidence suggests that low concentrations of 25-hydroxyvitamin D(3) (25OHD3) during gestation may be associated with a range of adverse health outcomes in later life. Retrospective estimation of perinatal vitamin D status using questionnaires is extremely unreliable and stored serum samples are rarely available. We aimed to validate the use of dried blood spots (DBS) to estimate perinatal vitamin D status and to determine whether inter-group differences in cord serum 25OHD3 are reflected in DBS. We examined 25OHD3 in 4-year-old frozen cord sera and matched DBS from neonates born at a hospital in Melbourne, Australia (n = 100). We examined the correlation between these values and also investigated whether the expected seasonal (winter/spring vs. summer/autumn) difference in serum 25OHD3 was reflected in DBS values. 25OHD3 was assayed in triplicate using tandem mass spectroscopy in both a 3 microL sample of cord serum and in matched 3 mm punches from archived DBS. 25OHD3 concentrations in neonatal cord serum and DBS were highly correlated (r = 0.85, P < 0.0001). As expected, serum 25OHD3 concentrations were higher in neonates born in summer/autumn (December to March) vs. winter/spring (April to November) (median 46.6 vs. 23.7 nmol/L, P < 0.0001). A comparable difference was seen in DBS values (17.8 vs. 10.5 nmol/L, P = 0.0001). Archived DBS samples provided a valid measure of perinatal vitamin D status and identified inter-seasonal differences in perinatal 25OHD3 concentrations. They could be used for case-control studies investigating the association between perinatal vitamin D status and later health outcomes.