Variation in placental type 2 11beta-hydroxysteroid dehydrogenase activity is not related to birth weight or placental weight

Maternal stress and placental function, a study using questionnaires and biomarkers at birth

Background

Prenatal stress affects the health of the pregnant woman and the fetus. Cortisol blood levels are elevated in pregnancy, and fetal exposure to cortisol is regulated by the placenta enzyme 11β-HSD2. A decrease in enzyme activity allows more maternal cortisol to pass through the placental barrier. Combining the fetal and maternal cortisol to cortisone ratio into the adjusted fetal cortisol exposure (AFCE) represents the activity of the enzyme 11β-HSD2 in the placenta.

Aim

To investigate the effect of prenatal maternal stress on the ratio of cortisol and cortisone in maternal and fetal blood at birth in a normal population.

Method

Maternal self-reported stress was assessed at one time-point, as late in the pregnancy as convenient for the participant, using the Depression Anxiety Stress Scales (DASS-42), Pregnancy Related Anxiety (PRA), and Major Life Events during pregnancy. The study included 273 participants from Copenhagen University Hospital. Maternal and umbilical cord blood was sampled directly after birth and cortisol and cortisone concentrations were quantified using UPLC chromatography. Data were analyzed in a five-step regression model with addition of possible confounders. The primary outcome was AFCE, and plasma concentrations of maternal and fetal cortisol and cortisone were secondary outcomes.

Results

Significant associations were seen for the primary outcome AFCE and the plasma concentrations of maternal cortisol and fetal cortisone with exposure to Pregnancy Related Anxiety (PRA), though the associations were reduced when adjusting for birth related variables, especially delivery mode. The weight of the placenta affected the associations of exposures on AFCE, but not plasma concentrations of cortisol and cortisone in mother and fetus. Moreover, the study demonstrated the importance of delivery mode and birth strain on cortisol levels right after delivery.

Conclusion

Our main finding was associations between PRA and AFCE, which shows the effect of maternal stress on placental cortisol metabolism.

Alterations of Cortisol Metabolism in Human Disorders

The interconversion of active and inactive corticosteroids - cortisol and cortisone, respectively, in humans - is modulated by isozymes of 11β-hydroxysteroid dehydrogenase (11-HSD). Studies of this process have provided crucial insights into glucocorticoid effects in a wide variety of tissues. The 11-HSD1 isozyme functions mainly as an oxoreductase (cortisone to cortisol) and is expressed at high levels in the liver and other glucocorticoid target tissues. Because it is required for full physiological effects of cortisol, it has emerged as a drug target for metabolic syndrome and type 2 diabetes. Mutations in the corresponding HSD11B1 gene, or in the H6PD gene encoding hexose-6-phosphate dehydrogenase (which supplies the NADPH required for the oxoreductase activity of 11-HSD1), cause apparent cortisone reductase deficiency, a rare syndrome of adrenocortical hyperactivity and hyperandrogenism. In contrast, the 11-HSD2 isozyme functions as a dehydrogenase (cortisol to cortisone) and is expressed mainly in mineralocorticoid target tissues, where it bars access of cortisol to the mineralocorticoid receptor. Mutations in the HSD11B2 gene encoding 11-HSD2 cause the syndrome of apparent mineralocorticoid excess, a severe form of familial hypertension. The role of this enzyme in the pathogenesis of common forms of low-renin hypertension remains uncertain.

11 beta-hydroxysteroid dehydrogenase 2 promoter methylation is associated with placental protein expression in small for gestational age newborns

Small for gestational age infants have greater risk of developing metabolic diseases in adult life. It has been suggested that low birth weight may result from glucocorticoid excess in utero, a key mechanism in fetal programming. The placental enzyme 11-beta hydroxysteroid dehydrogenase type 2 (11β-HSD2, HSD11B2 gene) acts as a barrier protecting the fetus from maternal corticosteroid deleterious effects. Low placental 11β-HSD2 transcription and activity have been associated with low birth weight, yet the mechanism regulating its protein expression is not fully understood. In the present study we aimed to analyze 11β-HSD2 protein expression in placentas of adequate and small for gestational age (AGA and SGA, respectively) newborns from healthy mothers, and to explore whether 11β-HSD2 protein expression could be modulated by DNA methylation. 11β-HSD2 protein levels were measured by western blot in placental biopsies from term AGA and SGA infants (n=10 per group). DNA methylation was profiled both globally and in the HSD11B2 promoter by liquid chromatography with UV detection and methylation-specific melting curve analysis, respectively. We found lower placental 11β-HSD2 protein expression and higher HSD11B2 promoter methylation in SGA compared to AGA. Promoter methylation was inversely correlated with both protein expression and, importantly, birth weight. No changes in global placental methylation were found. In conclusion, lower 11β-HSD2 protein expression is associated with higher HSD11B2 promoter methylation, correlating with birth weight in healthy pregnancy. Our data support the role of 11β-HSD2 in determining birth weight, providing evidence of its regulation by epigenetic mechanisms, which may affect postnatal metabolic disease risk.

Dysregulation of 11beta-hydroxysteroid dehydrogenases: implications during pregnancy and beyond

Glucococorticoids play a critical role in the developmental programing and fetal growth. Key molecules mediating and regulating tissue-specific glucocorticoid actions are 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1 and 2 isozymes, both of which are expressed in the placenta and the fetal membranes. 11beta-HSD1 is implicated in the pathogenesis of metabolic syndrome and its dysregulation has been observed in pregnancy-related complications (pre-eclampsia, intrauterine growth restriction). Interestingly, preliminary clinical data have associated certain 11beta-HSD1 gene polymorphisms with hypertensive disorders in pregnancy, suggesting, if confirmed by further targeted studies, it's potential as a putative prognostic marker. Animal studies and observations in humans have confirmed that 11beta-HSD2 insufficiency is related with pregnancy adversity (pre-eclampsia, intrauterine growth restriction, preterm birth). Importantly, down-regulation or deficiency of placental 11beta-HSD2 is associated with significant restriction in fetal growth and low-birth weight, and unfavorable cardio-metabolic profile in adulthood. The potential association of 11beta-HSD1 tissue-specific dysregulation with gestational diabetes, as well as the plausible utility of 11beta-HSD2, as a biomarker of pregnancy adversity and later life morbidity, are emerging areas of intense scientific interest and future investigation.

11β-Hydroxysteroid Dehydrogenase 2 in Preeclampsia

Preeclampsia is a serious medical problem affecting the mother and her child and influences their health not only during the pregnancy, but also many years after. Although preeclampsia is a subject of many research projects, the etiology of the condition remains unclear. One of the hypotheses related to the etiology of preeclampsia is the deficiency in placental 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2), the enzyme which in normal pregnancy protects the fetus from the excess of maternal cortisol. The reduced activity of the enzyme was observed in placentas from pregnancies complicated with preeclampsia. That suggests the overexposure of the developing child to maternal cortisol, which in high levels exerts proapoptotic effects and reduces fetal growth. The fetal growth restriction due to the diminished placental 11β-HSD2 function may be supported by the fact that preeclampsia is often accompanied with fetal hypotrophy. The causes of the reduced function of 11β-HSD2 in placental tissue are still discussed. This paper summarizes the phenomena that may affect the activity of the enzyme at various steps on the way from the gene to the protein.

Glucocorticoid Metabolism in Hypertensive Disorders of Pregnancy: Analysis of Plasma and Urinary Cortisol and Cortisone

Objectives

The aim of the study was to analyze the plasma and urinary cortisol (F) and cortisone (E) levels in normotensive and hypertensive pregnant women. The parameters known to reflect the function of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) were calculated to verify the changes in glucocorticoid balance over the course of gestational hypertension (GH) and pre-eclampsia (PE).

Materials and Methods

This retrospective case-control study included women in the third trimester of pregnancy, diagnosed with: GH (n = 29), PE (n = 26), or chronic hypertension (CH; n = 22). Normotensive women in their third trimester of pregnancy were also included (controls; n = 43). The plasma and urinary F and E levels were measured with the HPLC-FLD method. The 11β-HSD2 function was estimated by calculating the following ratios: plasma F/E and urinary free F to urinary free E (UFF/UFE). A statistical analysis was performed based on case-control structure.

Results and Discussion

PE was characterized by lower plasma F levels (639.0 nmol/L), UFF/Cr levels (3.80 μg/mmol) and F/E ratio (3.46) compared with that of the controls (811.7 nmol/L, 6.28 μg/mmol and 5.19, respectively) with marked abnormalities observed in the changes of F/E and UFF/UFE ratios with advancing gestation. GH patients showed significant disparities in the urinary steroid profile with lower UFF/UFE ratio (0.330 vs. 0.401) compared with the normotensive controls and abnormal changes in the UFF/UFE throughout pregnancy. The observed tendency towards lower F/E and UFF/UFE ratios in PE and GH patients may reflect more intensive F metabolism over the course of those disorders. In the normal pregnancy group, the plasma F/E and UFF/UFE ratios tended to present inverse correlations with advancing gestation. This trend was much less marked in PE and GH patients, suggesting that the abnormalities in 11β-HSD2 functions progressed with the GA. The birth weights of neonates born from pre-eclamptic pregnancies were lower than those from uncomplicated pregnancies, although only when the babies were born prematurely. Children born at term to normotensive mothers or mothers suffering from PE had comparable birth weights.

Diminished 11β-hydroxysteroid dehydrogenase type 2 activity is associated with decreased weight and weight gain across the first year of life

CONTEXT

Low birth weight is associated with adverse metabolic outcome in adulthood. Exposure to glucocorticoid (GC) excess in utero is associated with decreased birth weight, but the prospective longitudinal relationship between GC metabolism and growth has not been examined.

OBJECTIVE

We have hypothesized that changes in GC metabolism leading to increased availability may impair growth.

DESIGN

This was a prospective, longitudinal study with clinical measurements and 24-hour urinary steroid metabolite analysis at 1, 4, 12, 26, and 52 weeks after delivery in mothers and their babies.

SETTING

The study was conducted with observations and samples collected in the volunteers' own homes.

PARTICIPANTS

Healthy mothers and newborn babies/infants participated in the study.

INTERVENTIONS

There were no interventions.

MAIN OUTCOME MEASURES

Urinary steroid metabolite excretion quantified by gas chromatography/mass spectroscopy across the first year of life in relation to change in weight was measured.

RESULTS

The total production of the GC metabolites quantified increased across the first year of life. Markers of 11β-hydroxysteroid dehydrogenase type 1 activity increased from the age of 3 months as did those of 5α-reductase activity. After correcting for confounding variables, low markers of 11β-hydroxysteroid dehydrogenase type 2 activity was associated with reduced absolute weight and decreased weight gain over the first year of life. In the mothers, 5α-reductase activity was low at birth and progressively increased to normal over the first 6 months postpartum.

CONCLUSIONS

Increased GC exposure as a consequence of reduced 11β-hydroxysteroid dehydrogenase type 2 activity is likely to be a critical determinant of growth in early life. This not only highlights the central role of GCs and their metabolism, but also emphasizes the need for detailed longitudinal analyses.

Early-life glucocorticoid exposure: the hypothalamic-pituitary-adrenal axis, placental function, and long-term disease risk

An adverse early-life environment is associated with long-term disease consequences. Adversity early in life is hypothesized to elicit developmental adaptations that serve to improve fetal and postnatal survival and prepare the organism for a particular range of postnatal environments. These processes, although adaptive in their nature, may later prove to be maladaptive or disadvantageous if the prenatal and postnatal environments are widely discrepant. The exposure of the fetus to elevated levels of either endogenous or synthetic glucocorticoids is one model of early-life adversity that contributes substantially to the propensity of developing disease. Moreover, early-life glucocorticoid exposure has direct clinical relevance because synthetic glucocorticoids are routinely used in the management of women at risk of early preterm birth. In this regard, reports of adverse events in human newborns have raised concerns about the safety of glucocorticoid treatment; synthetic glucocorticoids have detrimental effects on fetal growth and development, childhood cognition, and long-term behavioral outcomes. Experimental evidence supports a link between prenatal exposure to synthetic glucocorticoids and alterations in fetal development and changes in placental function, and many of these alterations appear to be permanent. Because the placenta is the conduit between the maternal and fetal environments, it is likely that placental function plays a key role in mediating effects of fetal glucocorticoid exposure on hypothalamic-pituitary-adrenal axis development and long-term disease risk. Here we review recent insights into how the placenta responds to changes in the intrauterine glucocorticoid environment and discuss possible mechanisms by which the placenta mediates fetal hypothalamic-pituitary-adrenal development, metabolism, cardiovascular function, and reproduction.

Comparison between placental gene expression of 11β-hydroxysteroid dehydrogenases and infantile growth at 10 months of age

AIM

The local expression of two isoenzymes of 11β-hydroxysteroid dehydrogenase, type 1 (11βHSD-1) and type 2 (11βHSD-2), regulates the access of glucocorticoid hormones to their target cells. Reports on the association between the placental expression of 11βHSD and infantile growth are limited. The aim of the present study was to investigate if the placental gene expression of 11βHSD affects infantile growth at 10 months of age.

METHODS

Placentas and umbilical venous cord blood were obtained from 42 singleton cases of cesarean deliveries between 31 and 40 weeks of gestation at Hamamatsu University Hospital between March 2009 and June 2010. The gene expression of both 11βHSD-1 and 11βHSD-2 was measured by quantitative reverse transcription polymerase chain reaction. Adiponectin and leptin levels in umbilical cord blood were measured using enzyme-linked immunoassay.

RESULTS

11βHSD-1 and 11βHSD-2 gene expression in human placentas did not correlate with bodyweight or the ponderal index (PI) at 10 months of age, whereas the gene expression of 11βHSD-1, but not 11βHSD-2, correlated with birthweight as well as PI at birth. Adiponectin levels in umbilical cord blood significantly correlated with the placental gene expression of 11βHSD-1 as well as bodyweight and PI at 10 months of age, although no direct correlation was observed between them.

CONCLUSION

No direct correlation was observed between the placental gene expression of 11βHSD and infantile growth at 10 months of age. However, the placental gene expression of 11βHSD-1 may be indirectly connected with infantile growth via adiponectin-associated metabolic regulation represented by adiponectin levels in umbilical cord blood.

11β-hydroxysteroid dehydrogenases: intracellular gate-keepers of tissue glucocorticoid action

Glucocorticoid action on target tissues is determined by the density of "nuclear" receptors and intracellular metabolism by the two isozymes of 11β-hydroxysteroid dehydrogenase (11β-HSD) which catalyze interconversion of active cortisol and corticosterone with inert cortisone and 11-dehydrocorticosterone. 11β-HSD type 1, a predominant reductase in most intact cells, catalyzes the regeneration of active glucocorticoids, thus amplifying cellular action. 11β-HSD1 is widely expressed in liver, adipose tissue, muscle, pancreatic islets, adult brain, inflammatory cells, and gonads. 11β-HSD1 is selectively elevated in adipose tissue in obesity where it contributes to metabolic complications. Similarly, 11β-HSD1 is elevated in the ageing brain where it exacerbates glucocorticoid-associated cognitive decline. Deficiency or selective inhibition of 11β-HSD1 improves multiple metabolic syndrome parameters in rodent models and human clinical trials and similarly improves cognitive function with ageing. The efficacy of inhibitors in human therapy remains unclear. 11β-HSD2 is a high-affinity dehydrogenase that inactivates glucocorticoids. In the distal nephron, 11β-HSD2 ensures that only aldosterone is an agonist at mineralocorticoid receptors (MR). 11β-HSD2 inhibition or genetic deficiency causes apparent mineralocorticoid excess and hypertension due to inappropriate glucocorticoid activation of renal MR. The placenta and fetus also highly express 11β-HSD2 which, by inactivating glucocorticoids, prevents premature maturation of fetal tissues and consequent developmental "programming." The role of 11β-HSD2 as a marker of programming is being explored. The 11β-HSDs thus illuminate the emerging biology of intracrine control, afford important insights into human pathogenesis, and offer new tissue-restricted therapeutic avenues.

Site-specific methylation of placental HSD11B2 gene promoter is related to intrauterine growth restriction

Intrauterine growth restriction (IUGR) is associated with detrimental effects on neurodevelopmental progress in childhood and higher risk of degenerative diseases in adulthood. Placental 11β-hydroxysteroid dehydrogenase (HSD11B2) is a key gene involved in glucocorticoid metabolism, which in turn seems to be related to fetal growth impairment. As reduction of placental HSD11B2 gene expression has been associated with reduced human fetal growth, and methylation of HSD11B2 gene promoter has been shown to have an important role in HSD11B2 gene repression, we seek to investigate the relationship between IUGR and HSD11B2 gene promoter methylation in human placentas. We found that methylation levels of all studied CpG sites were significantly higher in IUGR newborns than those in controls. Further, methylation levels of the first and the third CpG sites were inversely associated with measures of fetal growth (birth weight and ponderal index). In addition, consistent with the above negative correlation, methylation levels of the first and the third CpG sites were inversely associated with HSD11B2 gene expression. These results together show a link between the site-specific methylation of placental HSD11B2 promoter and the development of IUGR.

Role of the hypothalamic-pituitary-adrenal axis in developmental programming of health and disease

Adverse environments during the fetal and neonatal development period may permanently program physiology and metabolism, and lead to increased risk of diseases in later life. Programming of the hypothalamic-pituitary-adrenal (HPA) axis is one of the key mechanisms that contribute to altered metabolism and response to stress. Programming of the HPA axis often involves epigenetic modification of the glucocorticoid receptor (GR) gene promoter, which influences tissue-specific GR expression patterns and response to stimuli. This review summarizes the current state of research on the HPA axis and programming of health and disease in the adult, focusing on the epigenetic regulation of GR gene expression patterns in response to fetal and neonatal stress. Aberrant GR gene expression patterns in the developing brain may have a significant negative impact on protection of the immature brain against hypoxic-ischemic encephalopathy in the critical period of development during and immediately after birth.

Glucocorticoids as mediators of developmental programming effects

Epidemiological evidence suggests that exposure to an adverse environment in early life is associated with an increased risk of cardio-metabolic and behavioral disorders in adulthood, a phenomenon termed 'early life programming'. One major hypothesis for early life programming is fetal glucocorticoid overexposure. In animal studies, prenatal glucocorticoid excess as a consequence of maternal stress or through exogenous administration to the mother or fetus is associated with programming effects on cardiovascular and metabolic systems and on the brain. These effects can be transmitted to subsequent generations. Studies in humans provide some evidence that prenatal glucocorticoid exposure may exert similar programming effects on glucose/insulin homeostasis, blood pressure and neurodevelopment. The mechanisms by which glucocorticoids mediate these effects are unclear but may include a role for epigenetic modifications. This review discusses the evidence for glucocorticoid programming in animal models and in humans.

Stress, glucocorticoids and liquorice in human pregnancy: programmers of the offspring brain

A suboptimal prenatal environment may induce permanent changes in cells, organs and physiology that alter social, emotional and cognitive functioning, and increase the risk of cardiometabolic and mental disorders in subsequent life ("developmental programming"). Although animal studies have provided a wealth of data on programming and its mechanisms, including on the role of stress and its glucocorticoid mediators, empirical evidence of these mechanisms in humans is still scanty. We review the existing human evidence on the effects of prenatal maternal stress, anxiety and depression, glucocorticoids and intake of liquorice (which inhibits the placental barrier to maternal glucocorticoids) on offspring developmental outcomes including, for instance, alterations in psychophysiological and neurocognitive functioning and mental health. This work lays the foundations for biomarker discovery and affords opportunities for prevention and interventions to ameliorate adverse outcomes in humans.

Glucocorticoids, prenatal stress and the programming of disease

An adverse foetal environment is associated with increased risk of cardiovascular, metabolic, neuroendocrine and psychological disorders in adulthood. Exposure to stress and its glucocorticoid hormone mediators may underpin this association. In humans and in animal models, prenatal stress, excess exogenous glucocorticoids or inhibition of 11β-hydroxysteroid dehydrogenase type 2 (HSD2; the placental barrier to maternal glucocorticoids) reduces birth weight and causes hyperglycemia, hypertension, increased HPA axis reactivity, and increased anxiety-related behaviour. Molecular mechanisms that underlie the 'developmental programming' effects of excess glucocorticoids/prenatal stress include epigenetic changes in target gene promoters. In the case of the intracellular glucocorticoid receptor (GR), this alters tissue-specific GR expression levels, which has persistent and profound effects on glucocorticoid signalling in certain tissues (e.g. brain, liver, and adipose). Crucially, changes in gene expression persist long after the initial challenge, predisposing the individual to disease in later life. Intriguingly, the effects of a challenged pregnancy appear to be transmitted possibly to one or two subsequent generations, suggesting that these epigenetic effects persist.

Differences in expression and activity of 11beta-hydroxysteroid dehydrogenase type 1 and 2 in human placentas of term pregnancies according to birth weight and gender

BACKGROUND

Fetal exposure to maternal glucocorticoids may determine fetal growth and the programing of later disorders. Availability of the glucocorticoids in the placenta is regulated by the 11beta-hydroxysteroid dehydrogenase (11beta-HSDs) enzymes. To date, there are discrepancies with regard to cortisol (F) cord blood levels in fetuses with intrauterine growth retardation in different species. Objective To study the expression and activity of 11beta-HSDs in placentas from full term small for gestational age (SGA), appropriate for gestational age (AGA) and large for gestational age (LGA) newborns, and cortisol cord blood concentration.

METHODS

Twenty-five placentas from AGA, 24 SGA and 25 LGA were collected.

RESULTS

SGA newborns had significantly lower and LGA newborns had significantly higher birth weight, birth length, head circumference, and placental weight than AGA counterparts. We observed a direct correlation between placental weight and birth weight, birth length and head circumference, and higher cord F levels in SGA newborns. The 11beta-HSD1 expression was similar among the SGA, AGA, and LGA placentas. However, within the placentas of SGA newborns, the 11beta-HSD1 mRNA levels were significantly reduced in the chorionic plate compared with basal plate. An inverse correlation between cord F levels and activity of 11beta-HSD1 in the chorionic plate of the SGA placentas was detected. The 11beta-HSD2 activity was seven- to eightfold higher compared with 11beta-HSD1 in the placentas, and there was a lower 11beta-HSD2 activity in females' SGA placentas compared with the male SGA placentas.

CONCLUSION

We observed a lower expression and activity of 11beta-HSD1 in the chorionic plate of the SGA placentas, suggesting a possible compensatory mechanism to diminish the higher cortisol fetal concentrations observed in fetuses with intrauterine growth restriction.

The p38 mitogen-activated protein kinase regulates 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) expression in human trophoblast cells through modulation of 11beta-HSD2 messenger ribonucleic acid stability

The placental 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2; encoded by the HSD11B2 gene) has emerged as a key player in controlling fetal development, but its regulation is incompletely understood. Here we identified p38 MAPK as an important regulator of placental 11beta-HSD2. We showed that inhibition of p38 MAPK with the pharmacological inhibitor SB202190 led to an approximately 50% reduction in 11beta-HSD2 activity, protein, and mRNA in primary human placental trophoblast cells. Furthermore, the effect of SB202190 was confirmed by the use of two additional p38 inhibitors, SB203580 and SB220025. In addition, SB202190 decreased the half-life of 11beta-HSD2 mRNA without altering the HSD11B2 promoter activity, indicating that p38 MAPK regulates placental 11beta-HSD2 expression through modulation of 11beta-HSD2 mRNA stability. Importantly, small interfering RNA-mediated knockdown of p38alpha caused a 50% reduction in 11beta-HSD2 activity, suggesting that p38alpha is the primary p38 isoform involved. Taken together, these findings suggest a novel pathway controlling placental 11beta-HSD2 expression resulting from the activation of p38 MAPK. Given that p38alpha is abundantly expressed in the human placenta in which its function is largely unknown, our present study also reveals 11beta-HSD2 as an important target through which p38alpha may regulate human placental function and consequently fetal growth and development.

Cadmium exposure during pregnancy reduces birth weight and increases maternal and foetal glucocorticoids

Cadmium exposure induces low birth weight through unknown mechanisms. Since low birth weight is associated to foetal exposure to high glucocorticoids (GC) concentrations, we hypothesized that low birth weight induced by prenatal exposure to Cd(2+) is, at least in part, mediated by higher foetal exposure to GC, specifically corticosterone, the main active GC in rodents. Pregnant rats were exposed to different dose of CdCl(2) administered in drinking water during the whole pregnancy period. At term, corticosterone was measured by enzyme immunoassay in maternal and foetal blood and in placental tissues. Cadmium was determined in placentas, maternal tissues (liver and kidney) and foetuses by inductively coupled plasma-mass spectrometry (ICP-MS). Placental 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) activity and expression were determined by a radiometric conversion assay and quantitative RT-PCR respectively. Results demonstrated that 50 ppm of Cd(2+), which was accumulated in different maternal tissues but not in the foetus, reduced pup birth weights and increased plasma corticosterone concentrations, both in mother and foetus. Placental 11beta-HSD2 activity and expression did not change by the treatment. We conclude that 50 ppm of Cd(2+) administered during pregnancy, increase foetal corticosterone concentrations due, probably, to alterations of the regulatory mechanisms of placental barrier to GC causing a mild but significant reduced birth weight.

Association between umbilical cord glucocorticoids and blood pressure at age 3 years

BACKGROUND

Animal data show that decreased activity of placental 11-beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), which potently inactivates glucocorticoids (e.g. cortisol) to inert forms (cortisone), allows increased access of maternal glucocorticoids to the fetus and 'programs' hypertension. Data in humans are limited. We examined in humans the association between venous umbilical cord blood glucocorticoids, a potential marker for placental 11beta-HSD2 enzyme activity, and blood pressure at age 3 years.

METHODS

Among 286 newborns in Project Viva, a prospective pre-birth cohort study based in eastern Massachusetts, we measured cortisol (F) and cortisone (E) in venous cord blood and used the ratio of F/E as a marker for placental 11beta-HSD2 activity. We measured blood pressure (BP) when the offspring reached age 3 years. Using mixed effects regression models to control for BP measurement conditions, maternal and child characteristics, we examined the association between the F/E ratio and child BP.

RESULTS

At age 3 years, each unit increase in the F/E ratio was associated with a 1.6 mm Hg increase in systolic BP (95% CI 0.0 to 3.1). The F/E ratio was not associated with diastolic blood pressure or birth weight for gestational age z-score.

CONCLUSION

A higher F/E ratio in umbilical venous cord blood, likely reflecting reduced placental 11beta-HSD2 activity, was associated with higher systolic blood pressure at age 3 years. Our data suggest that increased fetal exposure to active maternal glucocorticoids may program later systolic blood pressure.

Early-life events. Effects on aging

During the last two decades, a considerable body of evidence has emerged showing that circumstances during the fetal period and childhood may have lifelong programming effects on different body functions with a considerable impact on disease susceptibility. From a medical point of view, these long-term effects are today referred to as the Developmental Origins of Health and Disease (DOHaD) concept. The DOHaD concept may have a fundamental impact on our ideas about when and how to intervene in order to prevent aging-related loss of function and disease. The aim of this review is to provide a synopsis of epidemiological findings relating early-life conditions with key aging-related disorders, including cardiovascular disease, type 2 diabetes, depression, cognitive impairments and osteoporosis. There are several mechanisms that have been suggested as linking early-life events with late-life disease. This review will discuss programming of the hypothalamic-pituitary-adrenal axis function as one of the best characterised examples of such mechanisms.

Regulation of Placental Nutrient Transport – A Review

Fetal growth is primarily determined by nutrient availability, which is intimately related to placental nutrient transport. Detailed information on the regulation of placental nutrient transporters is therefore critical in order to understand the mechanisms underlying altered fetal growth and fetal programming. After briefly summarizing the cellular mechanisms for placental transport of glucose, amino acids and free fatty acids, we will discuss factors shown to regulate placental nutrient transporters and review the data describing how these factors are altered in pregnancy complications associated with abnormal fetal growth. We propose an integrated model of regulation of placental nutrient transport by maternal and placental factors in IUGR.

Simultaneously reduced gene expression of cortisol-activating and cortisol-inactivating enzymes in placentas of small-for-gestational-age neonates

OBJECTIVE

The enzyme 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) converts cortisol into cortisone. Reduced placental activity of 11beta-HSD2 in small-for-gestational-age (SGA) neonates results in fetal cortisol excess. In the present study, we examined the yet unknown gene expression of 11beta-HSD1, which primarily synthesizes cortisol in SGA placenta.

STUDY DESIGN

In placentas taken from 24 women with normal-weight newborns and 16 women with SGA neonates, expression of 11beta-HSD1 and 11beta-HSD2 messenger ribonucleic acid (mRNA) was determined using reverse transcription-polymerase chain reaction.

RESULTS

Placental mRNA expression of 11beta-HSD1 and 11beta-HSD2 was significantly reduced in the SGA group (P = .006 and P < .0001). Both enzymes showed a significant correlation to birthweight SD score and placental weight. Also, levels of both enzymes were significantly correlated.

CONCLUSION

In placental tissue of SGA neonates 11beta-HSD2 and 11beta-HSD1 gene expression is reduced. Adapted levels of 11beta-HSD1 might result in a counterregulatory mechanism limiting transplacental passage of elevated cortisol levels.

Epigenetic mechanisms of perinatal programming of hypothalamic-pituitary-adrenal function and health

Environmental effects on the materno-foetal interaction determine birth outcomes that predict health over the lifespan. Thus, maternal undernutrition or stress associate with low birth weight, leading to an increased risk of metabolic and cardiovascular illness in the offspring. We argue that these effects are, in part, mediated by direct and indirect effects on the hypothalamic-pituitary-adrenal (HPA) axis such that (i) the effect of maternal adversity on foetal growth is mediated by adrenal glucocorticoids and (ii) environmental adversity alters maternal physiology and behaviour, which then programs HPA activity in the offspring.

Role of the placenta in fetal programming: underlying mechanisms and potential interventional approaches

Adverse influences during fetal life alter the structure and function of distinct cells, organ systems or homoeostatic pathways, thereby ‘programming’ the individual for an increased risk of developing cardiovascular disease and diabetes in adult life. Fetal programming can be caused by a number of different perturbations in the maternal compartment, such as altered maternal nutrition and reduced utero–placental blood flow; however, the underlying mechanisms remain to be fully established. Perturbations in the maternal environment must be transmitted across the placenta in order to affect the fetus. Here, we review recent insights into how the placenta responds to changes in the maternal environment and discuss possible mechanisms by which the placenta mediates fetal programming. In IUGR (intrauterine growth restriction) pregnancies, the increased placental vascular resistance subjects the fetal heart to increased work load, representing a possible direct link between altered placental structure and fetal programming of cardiovascular disease. A decreased activity of placental 11β-HSD-2 (type 2 isoform of 11β-hydroxysteroid dehydrogenase) activity can increase fetal exposure to maternal cortisol, which programmes the fetus for later hypertension and metabolic disease. The placenta appears to function as a nutrient sensor regulating nutrient transport according to the ability of the maternal supply line to deliver nutrients. By directly regulating fetal nutrient supply and fetal growth, the placenta plays a central role in fetal programming. Furthermore, perturbations in the maternal compartment may affect the methylation status of placental genes and increase placental oxidative/nitrative stress, resulting in changes in placental function. Intervention strategies targeting the placenta in order to prevent or alleviate altered fetal growth and/or fetal programming include altering placental growth and nutrient transport by maternally administered IGFs (insulin-like growth factors) and altering maternal levels of methyl donors.

Glucocorticoid "Programming" and PTSD Risk

Epidemiological data have linked an adverse fetal environment with increased risks of cardiovascular, metabolic, neuroendocrine, and psychiatric disorders in adulthood. Prenatal stress and/or glucocorticoid excess might underlie this link. In animal models, prenatal stress, glucocorticoid exposure or inhibition/knockout of 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta-HSD-2), the feto-placental barrier to maternal glucocorticoids, reduces birth weight and causes permanent hypertension, hyperglycemia, increased hypothalamic-pituitary-adrenal (HPA) axis activity and behavior resembling of anxiety. In humans, 11 beta-HSD-2 gene mutations cause low birth weight and placental 11 beta-HSD-2 activity correlates directly with birth weight and inversely with infant blood pressure. Low birth weight babies have higher plasma cortisol levels throughout adult life, indicating HPA programming. In human pregnancy, severe maternal stress affects the offspring HPA axis and associates with neuropsychiatric disorders. Posttraumatic stress disorder (PTSD) appears to be a variable in the effects. Intriguingly, some of these effects appear to be 'inherited' into a further generation, itself unexposed to exogenous glucocorticoids at any point in the lifespan from fertilization, implying epigenetic marks persist into subsequent generation(s). Overall, the data suggest that prenatal exposure to excess glucocorticoids programs peripheral and CNS functions in adult life, predisposing to some pathologies, perhaps protecting from others, and these may be transmitted perhaps to one or two subsequent generations.

Endocrine regulation of human fetal growth: the role of the mother, placenta, and fetus

The environment in which the fetus develops is critical for its survival and long-term health. The regulation of normal human fetal growth involves many multidirectional interactions between the mother, placenta, and fetus. The mother supplies nutrients and oxygen to the fetus via the placenta. The fetus influences the provision of maternal nutrients via the placental production of hormones that regulate maternal metabolism. The placenta is the site of exchange between mother and fetus and regulates fetal growth via the production and metabolism of growth-regulating hormones such as IGFs and glucocorticoids. Adequate trophoblast invasion in early pregnancy and increased uteroplacental blood flow ensure sufficient growth of the uterus, placenta, and fetus. The placenta may respond to fetal endocrine signals to increase transport of maternal nutrients by growth of the placenta, by activation of transport systems, and by production of placental hormones to influence maternal physiology and even behavior. There are consequences of poor fetal growth both in the short term and long term, in the form of increased mortality and morbidity. Endocrine regulation of fetal growth involves interactions between the mother, placenta, and fetus, and these effects may program long-term physiology.

Proinflammatory cytokines inhibit human placental 11beta-hydroxysteroid dehydrogenase type 2 activity through Ca2+ and cAMP pathways

Excessive fetal exposure to glucocorticoids has been implicated in the etiology of adult metabolic and cardiovascular disease. Placental 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) may protect the fetus from excessive glucocorticoid exposure. Maternal stress may be accompanied by elevated levels of cortisol and increased proinflammatory cytokines [interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha (TNF-alpha)]. We hypothesize that proinflammatory cytokines inhibit human placental 11beta-HSD activity. We incubated explant cultures of term human placental villi in the presence or absence of 10 ng/ml IL-1beta, IL-6, or TNF-alpha, with or without agonists or antagonists of intracellular Ca2+ and adenylyl cyclase. Activity for 11beta-HSD2 was estimated using a radioisotope assay, and mRNA was measured using quantitative RT-PCR. All cytokines significantly (P < or = 0.05) reduced 11beta-HSD2 activity (>75% suppression); maximal inhibition occurred within 2 h and was maintained for at least 24 h. The IL-1beta-induced inhibitory activity was attenuated using a Ca2+ channel blocker (nifedipine), an intracellular Ca2+ antagonist [8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate], or the adenylyl cyclase stimulant forskolin. Conversely, 11beta-HSD2 activity was diminished in the presence of the Ca2+ ionophore A-23187 or the adenylyl cyclase inhibitor SQ-22536. mRNA levels for 11beta-HSD2 were not changed by any of the treatments. Proinflammatory cytokines inhibit human placental 11beta-HSD2 activity through a mechanism that involves increased intracellular Ca2+ and inhibition of adenylyl cyclase. This could result in excessive fetal exposure to maternal cortisol. This mechanism might mediate part of the increased risk of metabolic and cardiovascular disease in adult offspring.

Hypotheses on the Fetal Origins of Adult Diseases: Contributions of Epidemiological Studies

Epidemiological studies have demonstrated associations between low birth weight and cardiovascular disease, type 2 diabetes and their risk factors in adult life. These findings have led to sharp debates in the literature concerning potential methodological study flaws and the effect size and causality of the associations. More recent studies seem to have overcome most methodological flaws and suggest a small effect size of low birth weight on adult diseases for the individual. However, the effect size may still be important on a population level. Various causal pathways have been hypothesized as mechanisms underlying these associations. These hypotheses have proposed central roles for (1) fetal undernutrition, (2) increased cortisol exposure, (3) genetic susceptibility and (4) accelerated post-natal growth. These hypotheses have been studied in various epidemiological study designs. Thus far, it is still not known which mechanisms underlie the associations between low birth weight and diseases in adult life. The causal pathways linking low birth weight to diseases in later life seem to be complex and may include combined environmental and genetic mechanisms in various periods of life. Well-designed epidemiological studies are necessary to estimate the population effect size and to identify the underlying mechanisms. This knowledge is needed to develop strategies for identifying groups at risk and prevention focused on early life.

Glucocorticoid programming

Epidemiological evidence suggests that an adverse fetal environment permanently programs physiology, leading to increased risks of cardiovascular, metabolic, and neuroendocrine disorders in adulthood. Prenatal glucocorticoid excess or stress might link fetal maturation and adult pathophysiology. In a variety of animal models, prenatal glucocorticoid exposure or inhibition of 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), the fetoplacental "barrier" to maternal glucocorticoids, reduces birth weight and causes permanent hypertension, hyperglycemia, and increased hypothalamic-pituitary-adrenal axis (HPA) activity and behavior resembling anxiety. In humans, 11beta-HSD2 gene mutations cause low birth weight and reduced placental 11beta-HSD2 activity associated with intrauterine growth retardation. Low birth weight babies have higher plasma cortisol levels throughout adult life, indicating HPA programming. The molecular mechanisms may reflect permanent changes in the expression of specific transcription factors; key is the glucocorticoid receptor itself. Differential programming of the glucocorticoid receptor in different tissues reflects effects upon one or more of the multiple tissue-specific alternate first exons/promoters of the glucocorticoid receptor gene. Overall, the data suggest that either pharmacological or physiological exposure to excess glucocorticoids prenatally programs pathologies in adult life.

Different relationship between anthropometric markers and umbilical cord plasma leptin in Asian and Caucasian neonates

The leptin to fat ratio early in life could contribute to fixing the set point of leptin feedback at the hypothalamic level. Subjects from Asian and Caucasian ethnicities differ in body composition. We tested the hypothesis that anthropometric markers and their relationship to umbilical cord leptin, cortisol and cortisone, DHEAs and oestriol differed between Caucasians and Asians at birth. Birthweight, length, arm, calf and abdominal circumferences, scapular, triceps, quadriceps and abdominal skinfolds were measured in 180 healthy, full-term newborns of Asian and Caucasian ethnicities. Leptin and steroid hormone concentrations were determined in umbilical cord plasma. There was a significant difference in the slope of the regression between leptin and birthweight (p = 0.03) and calf circumference (p = 0.05) between male Caucasian and Asian neonates. In contrast, in female neonates, there was no significant difference (p = 0.099 and p = 0.07 for birthweight and calf circumference, respectively). In addition, while the slopes of the regression plots were not affected by gender in Asian newborns, there was a significant difference between male and female Caucasian newborns (p = 0.006 and p = 0.002 for birthweight and calf circumference, respectively). There was no significant correlation between cord leptin concentrations or anthropometric markers and steroid hormone concentrations. In conclusion, gender and ethnic differences in the relationship between leptin and anthropometric markers are detectable at birth between Asians and Caucasians, two ethnic groups that have been demonstrated to have different body compositions later in life. This may represent the first clinical evidence of a difference in leptin regulation between these two ethnic groups.

Reduced 11beta-hydroxysteroid dehydrogenase type 2 activity is associated with decreased birth weight centile in pregnancies complicated by asthma

Pregnancies complicated by asthma are associated with an increased risk of low birth weight. Currently, the mechanisms causing this outcome are unknown. To investigate whether impaired placental function may be a determinant, we measured placental 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) activity, protein and mRNA, placental CRH mRNA, fetal cortisol, and fetal estriol concentrations at delivery. Asthmatic subjects were classified according to inhaled glucocorticoid intake during pregnancy and compared with a control nonasthmatic group. There was a 25% reduction in neonatal birth weight centile in asthmatic women who did not use inhaled glucocorticoid treatment. This was accompanied by significantly reduced placental 11beta-HSD2 activity, significantly increased fetal cortisol, and a trend toward increased placental CRH mRNA and reduced fetal estriol concentrations. The use of inhaled glucocorticoids for treatment was associated with birth weight centile, 11beta-HSD2 activity, CRH mRNA, fetal cortisol, and estriol concentrations similar to control levels. There was a significant inverse correlation between fetal cortisol and fetal estriol concentrations across all groups. These studies demonstrate that inhaled glucocorticoid intake for the treatment of asthma is associated with improved placental function and fetal outcome, suggesting that inflammatory factors associated with asthma may be detrimental to fetal growth and development in these pregnancies.

The 11 beta-hydroxysteroid dehydrogenase type 2 activity in human placental microsomes is inactivated by zinc and the sulfhydryl modifying reagent N-ethylmaleimide

Proper glucocorticoid exposure in utero is vital to normal fetal organ growth and maturation. The human placental 11 beta-hydroxysteroid dehydrogenase type 2 enzyme (11 beta-HSD2) catalyzes the unidirectional conversion of cortisol to its inert metabolite cortisone, thereby controlling fetal exposure to maternal cortisol. The present study examined the effect of zinc and the relatively specific sulfhydryl modifying reagent N-ethylmaleimide (NEM) on the activity of 11 beta-HSD2 in human placental microsomes. Enzyme activity, reflected by the rate of conversion of cortisol to cortisone, was inactivated by NEM (IC(50)=10 microM), while the activity was markedly increased by the sulfhydryl protecting reagent dithiothreitol (DTT; EC(50)=1 mM). Furthermore, DTT blocked the NEM-induced inhibition of 11 beta-HSD2 activity. Taken together, these results suggested that the sulfhydryl (SH) group(s) of the microsomal 11 beta-HSD2 may be critical for enzyme activity. Zn(2+) also inactivated enzyme activity (IC(50)=2.5 microM), but through a novel mechanism not involving the SH groups. In addition, prior incubation of human placental microsomes with NAD(+) (cofactor) but not cortisol (substrate) resulted in a concentration-dependent increase (EC(50)=8 microM) in 11 beta-HSD2 activity, indicating that binding of NAD(+) to the microsomal 11 beta-HSD2 facilitated the conversion of cortisol to cortisone. Thus, this finding substantiates the previously proposed concept that a compulsorily ordered ternary complex mechanism may operate for 11 beta-HSD2, with NAD(+) binding first, followed by a conformational change allowing cortisol binding with high affinity. Collectively, the present results suggest that cellular mechanisms of SH group modification and intracellular levels of Zn(2+) may play an important role in regulation of placental 11 beta-HSD2 activity.

Fetal programming of stress responses

Epidemiological studies have shown that small size at birth is associated with an increased risk of coronary heart disease and its risk factors, including hypertension and Type 2 diabetes.It is suggested that these observations linking low birthweight with disease result from an imbalance between fetal nutrient demand and supply. This imbalance results in metabolic and endocrine adaptations, which benefit the fetus in the short term by reducing fetal growth and increasing fuel availability, but in the longer term they are maladaptive leading to an increased risk of coronary heart disease. Experimental data in animals and recent human observations have suggested that alterations in the set point of the hypothalamic-pituitary-adrenal axis and sympathoadrenal system are important long-term changes that occur in association with reduced fetal growth. These data suggest that the nature and amplitude of the stress response may be determined by intrauterine factors.

Pathophysiology of modulation of local glucocorticoid levels by 11beta-hydroxysteroid dehydrogenases

11beta-Hydroxysteroid dehydrogenases (11beta HSDs) are enzymes that catalyse the interconversion of active glucocorticoids (cortisol and corticosterone) into their inactive 11-keto products (cortisone and 11-deoxycorticosterone). Two isozymes have been identified: 11beta HSD type 1 is a predominant reductase, reactivating glucocorticoids from inert metabolites, whereas 11beta HSD type 2 is a potent dehydrogenase, inactivating glucocorticoids. They play a major role in the modulation of local cortisol levels and hence access of active steroid to corticosteroid receptors. This review focuses on the clinical importance of 11beta HSDs. We describe recent research that has not only advanced our understanding of the physiological role of these enzymes, but also their role in common diseases, including primary obesity and essential hypertension. These data provide encouragement that novel therapies will arise from a fuller understanding of the 11beta HSD system.

Reduced placental 11beta-hydroxysteroid dehydrogenase type 2 mRNA levels in human pregnancies complicated by intrauterine growth restriction: an analysis of possible mechanisms

11beta-Hydroxysteroid dehydrogenase type 2 (11beta-HSD2) inactivates cortisol to cortisone. In the placenta 11beta-HSD2 activity is thought to protect the fetus from the deleterious effects of maternal glucocorticoids. Patients with apparent mineralocorticoid excess owing to mutations in the 11beta-HSD2 gene invariably have reduced birth weight, and we have recently shown reduced placental 11beta-HSD2 activity in pregnancies complicated by intrauterine growth restriction. This is reflected in the literature by evidence of hypercortisolemia in the fetal circulation of small babies. In this study we have determined the levels of placental 11beta-HSD2 mRNA expression across normal gestation (n = 86 placentae) and in pregnancies complicated by intrauterine growth restriction (n = 19) and evaluated the underlying mechanism for any aberrant 11beta-HSD2 mRNA expression in intrauterine growth restriction. 11beta-HSD2 mRNA expression increased more than 50-fold across gestation, peaking at term. Placental 11beta-HSD2 mRNA levels were significantly decreased in intrauterine growth restriction pregnancies when compared with gestationally matched, appropriately grown placentae [e.g. at term DeltaCt (11beta-hydroxysteroid dehydrogenase type 2/18S) 12.8 +/- 0.8 (mean +/- SE) vs. 10.2 +/- 0.2, respectively, P < 0.001]. These differences were not attributable to changes in trophoblast mass in intrauterine growth restriction placentae, as assessed by parallel analyses of cytokeratin-8 mRNA expression. No mutations were found in the 11beta-HSD2 gene in the intrauterine growth restriction cohort, and imprinting analysis revealed that the 11beta-HSD2 gene was not imprinted. Although the underlying cause is unknown, 11beta-HSD2 gene expression is reduced in intrauterine growth restriction pregnancies. These data highlight the important role of 11beta-HSD2 in regulating fetal growth, a known factor in determining fetal morbidity but also the subsequent development of cardiovascular disease in adulthood.

Calcium inhibits human placental 11beta-hydroxysteroid dehydrogenase type 2 activity

The effect of Ca2+ on the conversion of cortisol to its inert metabolite cortisone, the reaction catalyzed by the microsomal enzyme 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), was investigated in human placental microsomes. Placental microsomal 11beta-HSD2 activity, as determined by the rate of conversion of cortisol to cortisone, was inhibited up to 50% by increasing free Ca2+ concentrations from 22 to 268 nM. The Ca2+-induced inhibition was reversible since chelation of endogenous Ca2+ with EGTA increased 11beta-HSD2 activity up to 200%. Ca2+ decreased the maximal velocity (Vmax) of the 11beta-HSD2 catalyzed conversion of cortisol to cortisone without altering the Km of 11beta-HSD2 for cortisol, indicating that Ca2+ modulates the catalytic efficiency rather than the substrate binding of 11beta-HSD2. Moreover, the Ca2+-induced inhibition does not appear to involve altered cofactor (NAD+) binding since the inhibition of microsomal 11beta-HSD2 activity by a sub-maximal concentration of free Ca2+ was not overcome by increasing the concentration of NAD+. These findings in the microsomes were then extended to an intact cell system, JEG-3 cells, an established model for human placental trophoblasts. In these cells, an increase in cytosolic free Ca2+ concentration ([Ca2+]i) elicited by a known physiological stimulus, PGF(2alpha), was accompanied by a 40% decrease in the level of 11beta-HSD2 activity. Furthermore, the PGF(2alpha)-induced inhibition of 11beta-HSD2 activity was abrogated when increases in [Ca2+]i were blocked with the intracellular Ca2+ chelator, BAPTA. Collectively, these results demonstrate for the first time that Ca2+ inhibits human placental 11beta-HSD2 activity by a post-translational mechanism not involving substrate or cofactor binding.

11 beta-hydroxysteroid dehydrogenase (11 beta-HSD-II) activity in human placenta: its relationship to placental weight and birth weight and its possible role in hypertension

It has been assumed that low birth weight and high placenta weight were key factors for predicting hypertension in human adulthood. A deficiency in placental 11 beta-HSD-II enzyme activity was supposed to be the underlying cause. To possibly establish 11 beta-HSD-II as a leading factor, we determined 11 beta-HSD-II activities in 133 healthy pregnancies, 21 proteinuric pregnancies complicated by pregnancy-induced hypertension (PIH), 26 non proteinuric PIH pregnancies and 15 pregnancies complicated by fetal growth restriction (32nd-41st gestational week). We could not identify differences in 11 beta-HSD-II activity between pregnancies with the rare combination of small babies with big placentas and others (p = 0.59; Kruskal-Wallis test). And although there was no correlation between 11 beta-HSD-II activity and birth weight, in the control gestational age correlated with 11 beta-HSD-II activity (r = 0.22; p < 0.05; Spearman). 11 beta-HSD-II activity in the proteinuric PIH group was significantly higher than in the controls (11.7 pmol/min/mg prot.; range 10-13.2 vs. 7.9; range 7.0-9.1; p < 0.05). The lowest, but not significant, enzyme activities were in the IUGR group (5.8 pmol/min/mg prot.; range 4.0-9.2). In this group, analysis of variance detected a correlation between enzyme activity and placental weight. In conclusion, we could not confirm that placental 11 beta-HSD-II deficiencies act as an indicator for the risk of adult hypertension in small fetuses with large placentas. However, in growth restriction 11 beta-HSD-II activity might play a role. To clarify the influence in this group, further research is needed. Increased 11 beta-HSD-II activities with gestational age in the control may serve to sustain fetal adrenal steroid genesis and to prepare the fetus for autonomic life.

11Beta-hydroxysteroid-dehydrogenase isoforms: tissue distribution and implications for clinical medicine

11Beta-hydroxylation is essential for glucocorticoid and mineralocorticoid activity of a steroid. The enzyme catalyzing this reaction is termed 11beta-hydroxysteroid-dehydrogenase (11beta-HSD). Two isoenzymes of 11beta-HSD have been characterized in human tissues. Whereas 11beta-HSD-I works mainly as a reductase, 11beta-HSD-II only functions as an oxidizing (inactivating) enzyme for physiological glucocorticoids. Thus, the tissue distribution of both enzymes plays a crucial role for the specific glucocorticoid status of an organ. This review summarizes our knowledge of tissue distribution of both 11beta-HSD isoenzymes, their physiological function and pathophysiological role in certain clinical abnormalities, and their relevance to the metabolism of synthetic glucocorticoid and mineralocorticoid compounds.

Glucocorticoids, 11beta-hydroxysteroid dehydrogenase, and fetal programming

Epidemiological studies in many distinct human populations have associated low weight or thinness at birth with a substantially increased risk of cardiovascular and metabolic disorders, including hypertension and insulin resistance/type 2 diabetes, in adult life. The concept of fetal "programming" has been advanced to explain this phenomenon. Prenatal glucocorticoid therapy reduces birthweight, and steroids are known to exert long-term organizational effects during specific "windows" of development. Therefore, we hypothesized that fetal overexposure to endogenous glucocorticoids might underpin the link between early life events and later disease. In rats, birthweight is reduced following prenatal exposure to the synthetic glucocorticoid dexamethasone, which readily crosses the placenta, or to carbenoxolone, which inhibits 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), the physiological feto-placental "barrier" to endogenous glucocorticoids. Although the offspring regain the weight deficit by weaning, as adults they exhibit permanent hypertension, hyperglycemia, and increased hypothalamic-pituitary-adrenal axis activity. Moreover, physiological variations in placental 11beta-HSD2 activity near term correlate directly with fetal weight. In humans, 11beta-HSD2 gene mutations produce a low birthweight, and some studies show reduced placental 11beta-HSD2 activity in association with intrauterine growth retardation. Moreover, low birthweight babies have higher plasma cortisol levels throughout adult life, indicating that hypothalamic-pituitary-adrenal axis programming also occurs in humans. The molecular mechanisms of glucocorticoid programming are beginning to be unraveled and involve permanent and tissue-specific changes in the expression of key genes, notably of the glucocorticoid receptor itself. Thus, glucocorticoid programming may explain, in part, the association between fetal events and subsequent disorders in adult life.

Impact of restriction of placental and fetal growth on expression of 11beta-hydroxysteroid dehydrogenase type 1 and type 2 messenger ribonucleic acid in the liver, kidney, and adrenal of the sheep fetus

We have investigated the effects of fetal growth restriction, induced by restriction of placental growth and function (PR), on 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD-1) and 11betaHSD-2 messenger RNA (mRNA) expression in fetal tissues in the sheep, using Northern blot analysis. Fetal liver, kidney, and adrenals were collected from normally grown fetuses at 90 days (n = 6), 125 days (n = 6), and 141-145 days (n = 7) and from PR fetuses at 141-145 days (n = 6). Expression of 11betaHSD-1 mRNA in the fetal liver increased significantly between 125 days (7.4+/-0.8) and 141-145 days gestation (27+/-5.3). There was also an approximately 2-fold increase in the ratio of 11betaHSD-1 mRNA/18S rRNA expression in the PR group (53.8+/-7.9) compared with that in control animals at 141-145 days gestation. There was a significant decrease in 11betaHSD-2 mRNA in fetal adrenals between 125 days (41.6+/-2.4) and 141-145 days (26.7+/-1.1) gestation, but there was no effect of PR on the expression of adrenal 11betaHSD-2 mRNA. 11betaHSD-2 mRNA expression in the fetal kidney increased between 90 days (16.8+/-1.7) and 141-145 days gestation (31.7+/-4.3), but there was no effect of PR on the levels of 11betaHSD-2 mRNA in the fetal kidney. In summary, 11betaHSD-2 mRNA is differentially regulated in the fetal adrenal and kidney in the sheep fetus during late gestation. There is also a specific increase in the expression of 11betaHSD-1 mRNA in the liver of growth-restricted fetuses in late gestation. This suggests that there is increased hepatic exposure to cortisol in the growth-restricted fetus, which may be important in the reprogramming of hepatic physiology that occurs after growth restriction in utero.

Maternal hypertension and progeny blood pressure: role of aldosterone and 11beta-HSD

Epidemiological and experimental evidence suggests that gestational events modulate the level of blood pressure that will be "normal" for the individual as an adult. Glucocorticoid excess during gestation is associated with low birth weight, a large placenta, and adult hypertension in humans and animals. It has been proposed that the deficiency in placental 11beta-hydroxysteroid dehydrogenase activity in humans produces a gestational hormonal milieu, notwithstanding normal circulating levels of glucocorticoids, that predisposes the adult progeny to hypertension. Animal studies indicate that maternal hypertension, excess glucocorticoids, and hydroxysteroid dehydrogenase inhibition program adult blood pressure. Blood pressures of Sprague-Dawley rat dams were manipulated during gestation with continuous intracerebroventricular infusions of vehicle, aldosterone, 11alpha-hydroxyprogesterone, or carbenoxolone at doses known to produce hypertension with no renal effects or with subcutaneous infusions of larger, equally hypertensinogenic doses that produce systemic effects. Blood pressures of all treated dams were significantly greater (P<0.01) during gestation than those of the vehicle ICV control rats but not significantly different from each other. The blood pressures of both male and female progeny (n>/=6 per group, comprising representatives from at least 4 litters) were measured after 6 weeks of age. No significant difference was found in the blood pressure of the pups regardless of the maternal gestational blood pressure or treatment with an enzyme inhibitor, even after high-salt diet challenge.

11beta-hydroxysteroid dehydrogenase type 2 is the predominant isozyme in the guinea pig placenta: decreases in messenger ribonucleic acid and activity at term

The type 2 isozyme of 11beta-hydroxysteroid dehydrogenase (11beta-HSD2) is responsible for inactivating physiologically active glucocorticoids to their inert metabolites. This is the predominant 11beta-HSD isozyme in the human placenta, where it is believed to protect the fetus from high levels of maternal cortisol. Given the similarity in placental structure between the human and the guinea pig (hemomonochorial), we have evaluated the potential of utilizing the guinea pig as a model to study the function and regulation of placental 11beta-HSD2 in fetal development. In this study, we characterized the intrinsic properties of 11beta-HSD in the guinea pig placenta during late pregnancy. The 11beta-HSD activity in the placenta was characteristic of 11beta-HSD2 in that it possessed only dehydrogenase activity that was NAD-dependent and had a high affinity for cortisol (Km = 134 nM). Moreover, the level of the 11beta-HSD2-like activity decreased significantly at term. To verify the expression of 11beta-HSD2 gene and to determine whether corresponding changes in 11beta-HSD2 mRNA occur at term, we also cloned the cDNA encoding guinea pig placental 11beta-HSD2. The deduced guinea pig 11beta-HSD2 enzyme contains 395 amino acids and shares over 80% sequence identity with other mammalian 11beta-HSD2 proteins. Northern blot analyses demonstrated the presence of the mRNA for 11beta-HSD2 but not that for 11beta-HSD1. Moreover, the level of 11beta-HSD2 mRNA decreased significantly at term. The parallel decrease in levels of 11beta-HSD2 activity and mRNA at term is consistent with, and provides a plausible molecular basis for, the previously reported increase in the rate of placental transfer of cortisol between mother and fetus at that time. In conclusion, the present study demonstrates that the guinea pig resembles the human in that 11beta-HSD2 is the predominant, if not exclusive, isozyme expressed in the placenta. Therefore, the guinea pig appears to represent a suitable model in which to study the role of placental 11beta-HSD2 in human fetal development.

Glucocorticoid actions and metabolism in pregnancy: implications for placental function and fetal cardiovascular activity

The isoforms of the enzyme 11beta hydroxysteroid dehydrogenase (11betaHSD) are expressed in placental tissue and fetal membranes. The two major isoforms, 11betaHSD-1 and 11betaHSD-2, are compartmentalized discretely, and regulated differentially by steroids (oestrogen, progesterone), activators of cAMP pathway, and nitric oxide. 11BetaHSD-2 appears important in human pregnancy in regulating the amount of maternal cortisol that crosses the placenta to reach the fetal compartment. On the other hand, 11betaHSD-1 may allow the local conversion of biologically inactive cortisone to biologically active cortisol, particularly within chorion trophoblasts. The localization, regulation, and importance of these isozymes are examined.