The effect of smoking on bone metabolism: maternal and cord blood bone marker levels

Total alkaline phosphatase levels by gestational age in a large sample of pregnant women

INTRODUCTION

Total alkaline phosphatase (tALP) levels rise physiologically in maternal serum during pregnancy, and excessively so in certain conditions. However, current reference values are dated, nonlinear, and based on small samples. Factors related to variation in tALP remain unexplained. Thus, our goals in this study were to establish a physiological development curve for tALP within low-risk pregnancies and to evaluate the factors influencing tALP values.

METHODS

This was a single-center, retrospective, observational study. All patients who delivered a live singleton infant at our center from January 1, 2011 to May 31, 2019, and had a tALP assay during pregnancy, were included regardless of the gestational age at which the assay was conducted.

RESULTS

A total of 2415 pregnancies were included. Median tALP decreased during the first trimester, it increased slightly during the second trimester, and then increased sharply during the third trimester. Factors associated with a significant increase in tALP were chronic histiocytic intervillositis, cholestasis, multiple pregnancies, liver disease, preeclampsia, smoking, and low weight for gestational age. Conversely, gestational diabetes was associated with a discrete decrease in tALP.

DISCUSSION

Our large sample allowed establishment of tALP reference curves based on gestational age. To interpret these results more thoroughly, factors that influence tALP rates should be further scrutinized.

Comprehensive metabolic characterization of serum osteocalcin action in a large non-diabetic sample

Recent research suggested a metabolic implication of osteocalcin (OCN) in e.g. insulin sensitivity or steroid production. We used an untargeted metabolomics approach by analyzing plasma and urine samples of 931 participants using mass spectrometry to reveal further metabolic actions of OCN. Several detected relations between OCN and metabolites were strongly linked to renal function, however, a number of associations remained significant after adjustment for renal function. Intermediates of proline catabolism were associated with OCN reflecting the implication in bone metabolism. The association to kynurenine points towards a pro-inflammatory state with increasing OCN. Inverse relations with intermediates of branch-chained amino acid metabolism suggest a link to energy metabolism. Finally, urinary surrogate markers of smoking highlight its adverse effect on OCN metabolism. In conclusion, the present study provides a read-out of metabolic actions of OCN. However, most of the associations were weak arguing for a limited role of OCN in whole-body metabolism.

Effects of Maternal Hypoxia during Pregnancy on Bone Development in Offspring: A Guinea Pig Model

Low birth weight is associated with reduced bone mass and density in adult life. However, effects of maternal hypoxia (MH) on offspring bone development are not known. Objective. The current study investigated the effects of fetal growth restriction induced by MH during the last half of gestation on bone structure and volume in the offspring of the fetus near term and the pup in adolescence. Methods. During 35-62-day gestation (term, 69d), guinea pigs were housed in room air (21% O2; control) or 12% O2 (MH). Offspring femur and tibia were collected at 62d gestation and 120d after birth. Results. MH decreased fetal birth weight but did not affect osteogenic potential pools in the fetal bone marrow. Histological analysis showed no effects of MH on tibial growth plate thickness in either fetal or postnatal offspring, although there was increased VEGF mRNA expression in the growth plate of postnatal offspring. MH did not change primary spongiosa height but lowered collagen-1 mRNA expression in postnatal offspring. There was increased mRNA expression of adipogenesis-related gene (FABP4) in bone from the MH postnatal offspring. Conclusion. MH during late gestation did not change the pool of osteogenic cells before birth or growth plate heights before and after birth. However, MH reduced expression of bone formation marker (collagen-1) and increased expression of fat formation marker (FABP4) in postnatal offspring bone.

The effect of cigarette smoke exposure on vitamin D level and biochemical parameters of mothers and neonates

BACKGROUND

Exposure to cigarette smoke during pregnancy leads to several adverse effects on mother and child. The purpose of this study was to evaluate the effect of being a passive smoker during pregnancy on vitamin D level and related biochemical indices including parathyroid hormone, calcium, phosphorus and alkaline phosphatase in mothers and newborns.

METHODS

One hundred eight pregnant women and their newborns participated in a historical cohort study in two equal groups (n = 54) with and without cigarette smoke exposure. Maternal blood and urine samples and blood samples of umbilical cord were obtained in the delivery room. Concentration of 25-hydroxy vitamin D and related biochemical indices in samples of maternal and cord blood were investigated. Exposure to cigarette smoke was evaluated through questionnaire and maternal urine and umbilical cord serum cotinine levels.

RESULTS

The mean level of 25-hydroxyvitamin D in maternal serum was 9.28 ± 5.19 ng/mlin exposed and 10.75 ± 5.26 ng/ml in non-exposed group(p > 0.05). The mean concentration of 25-hydroxy vitamin D in cord serum was 10.83 ± 6.68 ng/ml in the exposed and 11.05 ± 4.99 ng/ml in the non-exposed group(p > 0.05). The exposed mothers had significantly higher parathyroid hormone level (p = 0.013), lower serum calcium (p = 0.024) and higher serum alkaline phosphatase (p = 0.024). There was a significant correlation between maternal and umbilical cord serum 25-hydroxyvitamin D within both exposed and non-exposed groups (p < 0.001).

CONCLUSION

Maternal exposure to cigarette smoking during pregnancy negatively influences serum calcium level and increase parathyroid hormone and alkaline phosphatase in mothers.

Foetal exposure to maternal passive smoking is associated with childhood asthma, allergic rhinitis, and eczema

Objective. We examined the hypothesis that foetal exposure to maternal passive smoking is associated with childhood asthma, allergic rhinitis, and eczema. Methods. The study was a population-based cross-sectional survey of Hong Kong Chinese children aged ≤14 years carried out in 2005 to 2006. Results. Foetal exposure to maternal passive smoking was significantly associated with wheeze ever (OR 2.05; 95% CI 1.58–2.67), current wheeze (OR 2.06; 95% CI 1.48–2.86), allergic rhinitis ever (OR 1.22; 95% CI 1.09–1.37), and eczema ever (OR 1.61; 95% CI 1.38–1.87). Foetal exposure to maternal active smoking was significantly associated with asthma ever (OR 2.10; 95% CI 1.14–3.84), wheeze ever (OR 2.46; 95% CI 1.27–4.78), and current wheeze (OR 2.74; 95% CI 1.24–6.01) but not with allergic rhinitis ever (OR 1.01; 95% CI 0.70–1.46) or eczema ever (OR 1.38; 95% CI 0.87–2.18). The dose response relationship between wheeze ever and current wheeze with increasing exposure, from no exposure to maternal passive smoking and then to maternal active smoking, further supports causality. Conclusion. There is significant association between foetal exposure to maternal passive smoking and maternal active smoking with childhood asthma and related atopic illnesses. Further studies are warranted to explore the potential causal relationship.

Quantitative ultrasound measurements in premature infants at 1 year of age: the effects of antenatal administered corticosteroids

The aim of this study was to evaluate the effects of antenatally administered glucocorticoids on bone status of preterm infants at 1 year corrected age. The study population consisted of 32 preterm infants with a gestational age of 24-34 weeks. The infants were divided into two groups according to antenatal exposure to corticosteroids. Quantitative ultrasound (QUS) assessment of bone was performed in the study infants at the corrected age of 1 year. Blood levels of carboxy-terminal propeptide of type I procollagen (PICP) and carboxy-terminal telopeptide of type I collagen (ICTP) were measured at birth and at 1 year corrected age. Levels of PICP and ICTP were significantly lower at birth in corticosteroid-exposed neonates (P < 0.05). At corrected age of 12 months ICTP levels remained significantly lower in corticosteroid-exposed infants, but we found no significant difference in levels of the bone-formation marker PICP between corticosteroid-exposed and nonexposed infants. In the majority of participant preterm infants bone speed of sound (SOS) was within age-adjusted normal values of full-term infants. There was no significant difference in bone SOS between exposed and nonexposed infants at corrected age of 12 months. There was no correlation between SOS and levels of bone markers. The results of our study indicate that, despite the suppression of fetal bone turnover at birth in corticosteroid-exposed infants, antenatal glucocorticoid treatment seems to have no long-term impact on bone status of preterm infants assessed by QUS complementary to measurement of bone-turnover markers at 1 year corrected age.

Cigarette smoke inhalation modulates gene expression in sites of bone healing: a study in rats

OBJECTIVE

The aim of this study was to assess the effect of cigarette smoke inhalation (CSI) on gene expression in alveolar bone healing sites.

STUDY DESIGN

Wistar rats were randomly assigned to the groups: control [animals not exposed to CSI (n = 20)] and test [animals exposed to CSI, starting 3 days before teeth extraction and maintained until killing them (n = 20)]. First mandibular molars were bilaterally extracted, and the expression of alkaline phosphatase, bone morphogenetic protein (BMP) 2 and 7, receptor activator of nuclear factor κB ligand, osteoprotegerin, and d2 isoform of vacuolar adenosine triphosphatase V(0) domain were assessed by quantitative polymerase chain reaction in the newly formed tissue in the sockets.

RESULTS

Overall, data analysis demonstrated that CSI significantly affected the expression pattern of all of the studied genes except BMP-7.

CONCLUSION

The expression of key genes for bone healing may be affected by CSI in tooth extraction sites.

Maternal vitamin D status determines bone variables in the newborn

CONTEXT

Vitamin D regulates 3% of the human genome, including effects on bone health throughout life. Maternal vitamin D status may program neonatal skeletal development. The objective here was to determine the association of mothers' vitamin D status with bone variables of their newborns.

SUBJECTS AND METHODS

In a birth hospital, pregnant women (n = 125) participated in a cross-sectional study with a longitudinal follow-up of the pregnancy. The mean (sd) values for age, body mass index before pregnancy, pregnancy weight gain, and total vitamin D intake in mothers were 31 (4) yr, 23.5 (3.7) kg/m(2), 13.1 (4.3) kg, and 14.3 (5.8) microg, respectively. All newborns were full-term, 99% were appropriate for gestational age, and 53% were boys. Blood samples were collected from mothers during the first trimester and 2 d postpartum and from umbilical cords at birth for analysis of serum 25-hydroxyvitamin D (S-25-OHD), PTH, and bone remodeling markers. Bone variables were measured by pQCT at the 20% site of the newborn tibia on an average of 10 (11) d postpartum. Bone contour was analyzed with a single threshold of 180 mg/mm(3) for the detection of total bone mineral density (BMD), bone mineral content (BMC), and cross-sectional area (CSA).

RESULTS

Mean S-25-OHD was 41.0 (13.6), 45.1 (11.9), and 50.7 (14.9) nmol/liter during the first trimester, postpartum, and in the umbilical cord, respectively. The median value of the individual means for first trimester and the 2-d postpartum S-25-OHD was 42.6 nmol/liter, which was used as cutoff to define two equal-sized groups. Groups are called below median and above median in the text. Newborns below median were heavier (P = 0.05), and 60% were boys. Tibia bone mineral content was 0.047 (95% confidence interval, 0.011-0.082) g/cm higher (P = 0.01), and cross-sectional area was 12.3 (95% confidence interval, 2.0-22.6) mm(2) larger (P = 0.02), but no difference in bone mineral density was observed, above median compared with below median group. These results were adjusted for newborn Z-score birth weight, maternal height, and newborn age at the measurement. A positive, significant correlation was observed between remodeling markers in mothers at different time points and above median group in the cord.

CONCLUSIONS

Although the mean total intake of vitamin D among mothers met current Nordic recommendations, 71% of women and 15% of newborns were vitamin D deficient during the pregnancy. Our results suggest that maternal vitamin D status affects bone mineral accrual during the intrauterine period and influences bone size. More efforts should be made to revise current nutrition recommendations for pregnant women that may have permanent effects on the well-being of children.

Maternal smoking and the vitamin D-parathyroid hormone system during the perinatal period

OBJECTIVE

To evaluate the effect of smoking on the vitamin D-parathyroid hormone (PTH) system during the perinatal period.

STUDY DESIGN

Sixty-one healthy women with singleton pregnancies and their newborns participated in a cohort study. We compared serum PTH and BsmI polymorphism of the vitamin D receptor gene, 25 hydroxyvitamin D (25(OH)D), 1,25 dihydroxyvitamin D, calcium, phosphorus, and bone alkaline phosphatase (bALP) in a smoking group (n = 32) versus a non-smoking group (n = 29), controlling for lifestyle confounders. The mothers were examined at 30 to 32 weeks and 38 to 40 weeks of pregnancy, and the infants were examined at 2 to 3 days of postnatal life.

RESULTS

Mothers who smoked and their newborns showed decreased serum PTH (30-32 weeks, 26.9 +/- 10.7 pg/mL versus 37.1+/-19.5 pg/mL; 38-40 weeks, 32.2 +/- 13.5 pg/mL versus 46.2 +/- 21.9 pg/mL, P = .005; newborns, 43.4 +/- 21.8 versus 64.1 +/- 34.2 pg/mL, P = .02) and increased phosphorus. Newborns of mothers who smoked also had significantly lower anthropometric measurements and serum 25(OH)D (14.2 +/- 6.2 ng/mL versus 22.3 +/- 11.3 ng/mL, P = .009). In addition, pregnant women who smoked had lower bALP (30-32 weeks, 31 +/- 15 U/L versus 44+/-29 U/L; 38-40 weeks, 55 +/- 32 U/L versus 97 +/- 62 U/L, P = .005).

CONCLUSIONS

Smoking during pregnancy negatively influences calcium-regulating hormones, leading to relative hypoparathyroidism in both the mother and their newborns.

Morphological and biological effects of maternal exposure to tobacco smoke on the feto-placental unit

Active and passive maternal smoking has a damaging effect in every trimester of human pregnancy. Cigarette smoke contains scores of toxins which exert a direct effect on the placental and fetal cell proliferation and differentiation and can explain the increased risk of miscarriage, fetal growth restriction (FGR) stillbirth, preterm birth and placental abruption reported by epidemiological studies. In the placenta, smoking is associated from early in pregnancy, with a thickening of the trophoblastic basement membrane, an increase in collagen content of the villous mesenchyme and a decrease in vascularisation. These anatomical changes are associated with changes in placental enzymatic and synthetic functions. In particular, nicotine depresses active amino-acid (AA) uptake by human placental villi and trophoblast invasion and cadmium decreases the expression and activity of 11 beta-hydroxysteroid dehydrogenase type 2 which is causally linked to FGR. Maternal smoking also dysregulates trophoblast expression of molecules that govern cellular responses to oxygen tension. In the fetus, smoking is associated with a reduction of weight, fat mass and most anthropometric parameters and as in the placenta with alterations in protein metabolism and enzyme activity. These alterations are the results of a direct toxic effect on the fetal cells or an indirect effect through damage to, and/or functional disturbances of the placenta. In particular, smoking interferes strongly with the fetal brain and pancreas biological parameters and induces chromosomal instability, which is associated with an increase in the risk of cancer, especially childhood malignancies.

Leptin and bone turnover in monochorionic twins complicated by twin-twin transfusion syndrome

INTRODUCTION

To test the hypothesis that the bone metabolism of a growth-restricted foetus is regulated by genetic, placental and/or foetal factors through leptin, we investigated the foetal bone turnover in monochorionic pregnancies complicated with or without twin-twin transfusion syndrome (TTTS).

METHODS

Maternal and cord bloods were collected from gestational-age-matched monochorionic twins with (n=15) and without (n=15) TTTS. The samples were assayed for leptin, cross-linked carboxyl terminal telo-peptide (ICTP, a marker of bone resorption) and pro-peptide (PICP, a marker of bone formation) of type I collagen by radioimmunoassay (RIA).

RESULTS

In the growth-restricted donor twin, the plasma concentration of leptin (P < 0.001), PICP (P < 0.001) was lower, while that of ICTP (P < 0.001) was higher than the recipient twin of the TTTS group. In contrast, leptin, PICP and ICTP were comparable in non-TTTS twins. In the recipient twin of TTTS and non-TTTS twins, leptin was positively associated with PICP (r=0.73; n=45, P < 0.001) and negatively with ICTP (r=-0.68; n=45; P < 0.001). No such association was found between leptin and bone marker in the growth-restricted donor twin of the TTTS group.

CONCLUSION

Our data suggest that, in AGA twins, leptin maintains bone metabolism by inhibiting resorption and enhancing bone formation. In contrast, growth-restricted donor twins have high bone turnover and this does not seem to be due to leptin deficiency.

Levels of bone collagen markers in preterm infants: relation to antenatal glucocorticoid treatment

Although the beneficial effects of antenatally administered glucocorticoids are well documented, data on the potential of adverse consequences are limited. The objective of this study was to determine the effects of antenatally administered glucocorticoids on biochemical markers of bone metabolism of 55 preterm infants with a gestational age of 24-34 weeks who were enrolled in the study. Neonates were divided into two groups according to antenatal exposure to corticosteroids. There were no significant differences between the groups in clinical characteristics and anthropometric variables. We studied blood levels of osteocalcin (OC), carboxy-terminal propeptide of type I procollagen (PICP), and carboxy-terminal telopeptide of type I collagen (ICTP) at the time of delivery, on postnatal day 10, and at 2 and 4 months of life. Comparing the groups, we found statistically significant reduction in PICP levels at birth in corticosteroid-exposed neonates (P < 0.05). The levels of bone markers increased progressively on the first days of life. There were no significant differences between groups in bone markers at 10 days or at 2 and 4 months of life. We found no significant difference for bone markers between groups of infants exposed to single or repeated maternal corticosteroid treatments. In summary, antenatal glucocorticoid treatments are suggested to have a negative impact on fetal bone formation as reflected by low PICP levels at birth. However, this negative effect on bone markers seems to be a temporary effect that subsides on the first days of life and afterward.

Type 1 collagen marker of bone turnover, insulin-like growth factor, and leptin in dichorionic twins with discordant birth weight

OBJECTIVE

We investigated the relationship between IGF-I-IGF binding protein (IGFBP)-1 and leptin levels with type 1 collagen markers of bone turnover in dichorionic twins with or without discordant birth weight of 20% or greater.

METHODS

Maternal and cord bloods were collected from gestational age-matched dichorionic twins with (n = 16) or without (n = 16) discordant birth weight. The samples were assayed for cross-linked carboxyl terminal telopeptide (ICTP, a marker of bone resorption) and propeptide (PICP, a marker of bone formation) of type I collagen, leptin, IGF-I, and IGFBP-1 by RIA.

RESULTS

The intrauterine growth-restricted (IUGR) twins of the discordant group had higher fetal ICTP (P < 0.001) and IGFBP-1 (P < 0.001) levels, whereas PICP (P < 0.001), IGF-I (P < 0.001), and leptin (P < 0.001) were lower than the cotwins with normal weight (AGA). In contrast, concentrations of IGF-I, IGFBP-1, ICTP, PICP, and leptin were comparable between concordant twin pairs. Leptin levels were positively correlated with PICP (r = 0.61; P < 0.001) and negatively with ICTP (r = -0.57; P < 0.001) in concordant and AGA twins but not in IUGR twins. In IUGR twins, IGF-I had positive association with PICP (r = 0.76; P < 0.001) and negative association with ICTP (r= -0.76; P < 0.001), whereas IGFBP-1 was negatively correlated with PICP levels (r = -0.65; P < 0.01). No such association was found in concordant and AGA twins.

CONCLUSION

These data suggest that IUGR twins had high bone turnover, which is independent of maternal factors and perhaps may be due to altered IGF axis.

Elevated IGFBP-1 cause high bone turnover in growth-restricted monochorionic twins with discordant birth weight

OBJECTIVE

To test the hypothesis that low birth weight twins have a higher risk of osteoportotic fracture in later life, we investigated the association between fetal IGF axis and type-1 collagen markers of bone turnover in monochorionic (MC) twins with or without discordant birth weight of >or=20%.

METHODS

Maternal and cord bloods were collected from gestational age matched MC twins of discordant (n = 16) and concordant birth weights (n = 16). The samples were assayed for cross linked carboxyl terminal telopeptide (ICTP, a marker of bone resorption) and pro-peptide (PICP, a marker of bone formation) of type I collagen, IGF-1, and IGFBP-1 by radio-immunoassay.

RESULTS

The growth-restricted twins (IUGR) of discordant group had higher fetal IGFBP-1 and ICTP (P < 0.001) levels, while PICP (P < 0.001) was lower than the co-twins with normal weight (AGA). In contrast, cord blood levels of IGF-1, IGFBP-1, ICTP, and PICP in concordant twin pairs were comparable to AGA twins. The concordant and AGA twins had a positive correlation between ICTP and PICP levels (y = 23x - 711; r = 0.84; P < 0.001; n = 48) but no such association was found in IUGR twins. Instead, IGFBP-1 levels in IUGR twins had a negative association with PICP (r = 0.81; P < 0.001; n = 16) and a positive correlation with ICTP (r- = 0.51; P < 0.05; n = 16). No such association was found in concordant and AGA twins.

CONCLUSION

These data suggest that growth-restricted twins had high bone turnover, due to elevated IGFBP-1. This association seems to be independent of maternal and genetic factors.

Calcium Homeostasis in Human Placenta: Role of Calcium‐Handling Proteins

The human placenta is a transitory organ, representing during pregnancy the unique connection between the mother and her fetus. The syncytiotrophoblast represents the specialized unit in the placenta that is directly involved in fetal nutrition, mainly involving essential nutrients, such as lipids, amino acids, and calcium. This ion is of particular interest since it is actively transported by the placenta throughout pregnancy and is associated with many roles during intrauterine life. At term, the human fetus has accumulated about 25-30 g of calcium. This transfer allows adequate fetal growth and development, since calcium is vital for fetal skeleton mineralization and many cellular functions, such as signal transduction, neurotransmitter release, and cellular growth. Thus, there are many proteins involved in calcium homeostasis in the human placenta.