Cellular growth and differentiation during embryogenesis and fetal development. The role of vitamin D

Implications of maternal vitamin D administration for the neonatal respiratory distress syndrome: A randomized clinical trial

BACKGROUND

Vitamin D deficiency has been suggested to be a risk factor for neonatal respiratory distress syndrome (RDS). This study aimed to evaluate the effect of 25 (OH) D administrations in pregnant women with findings of preterm labor on the incidence of RDS in their preterm neonates.

MATERIALS AND METHODS

A randomized controlled clinical trial was conducted on pregnant mothers with gestational age (GA) of less than 34 weeks at risk of preterm delivery. 175 subjects were randomly assigned into two groups, including intervention (intramuscular injection of 50,000 units of 25(OH) D during 72 hours before delivery) and control (no injections). Serum concentrations of 25(OH) D were measured shortly after birth in both mothers and neonates. Then, clinical and laboratory results of mothers and their offspring were recorded (in a checklist). Short-term outcomes and the need for respiratory support were also assessed. Data were analyzed by independent t-test, Mann-Whitney U test, Fisher's exact test, and chi-square test.

RESULTS

Even though gestational age, birth weight, delivery method, and serum vitamin D levels are consistent among both groups, 45% of neonates in the control group and 20% in the intervention group developed respiratory distress syndrome (P = 0.05). The mean 25(OH) D level in neonates was 17.7±10.5 and 19.29±9.94 ng/mL in the intervention and control groups, respectively (P > 0.05).

CONCLUSION

A single dose of 50,000 units of intramuscular 25(OH)D in pregnant women at risk of preterm labor can lower the risk of RDS in the infant.

Association of vitamin D status at birth with pulmonary disease morbidity in very preterm infants

OBJECTIVE

We aimed to assess whether serum 25-hydroxyvitamin D (25(OH)D) levels at birth are associated with pulmonary disease morbidities in very preterm infants.

METHODS

This prospective cohort analysis included 93 infants born before 32 weeks of gestation in the Second Xiangya Hospital of Central South University between March 2016 and February 2017. Participants were classified into three groups according to their 25(OH)D levels at birth. The groups were compared in terms of demographic variables and pulmonary disease morbidities.

RESULTS

The mean serum 25(OH)D level at birth was 35.7 ± 19.1 nmol/L, and 38 (40.9%), 31 (33.3%), and 24 (25.8%) infants had 25(OH)D levels of less than 25 nmol/L, 25-50 nmol/L, and more than or equal to 50 nmol/L, respectively. There was a statistically significant difference in neonatal respiratory distress syndrome (RDS) rates among the three groups (43.6% vs. 35.9% vs. 20.5%, p = .029). The rates of bronchopulmonary dysplasia, apnea, respiratory failure, persistent pulmonary hypertension, and pulmonary hemorrhage did not differ significantly among the groups. Logistic analysis, adjusted for gestational age and birth weight, showed that a low serum 25(OH)D level (<50 nmol/L) was a risk factor for RDS (odds ratio, 0.195; p = .017).

CONCLUSION

There was a high prevalence of low 25(OH)D levels (<50 nmol/L) and an association between vitamin D status and RDS in very preterm infants. However, more research on this association is required.

Association of vitamin D receptor gene FokI and TaqI polymorphisms and risk of RDS

Background: Vitamin D and its receptor (VDR) have important roles in perinatal lung development. The objective of this study was to investigate the possible association between VDR FokI and TaqI polymorphism and development of respiratory distress syndrome (RDS) in preterm infants.Method: A total of 173 premature infants <34 weeks: 82 with RDS and 91 without RDS were enrolled. Genotyping of VDR polymorphisms was assayed by real-time PCR. Serum 25-hydroxyvitamin D (25-OHD) levels were measured by ELISA in blood samples that were obtained at the time of admission to the neonatal intensive care unit.Results: Gestational age (GA) was significantly lower in the RDS group compared with the controls. In univariate analysis, VDR TaqI CT and CC genotypes were associated with the increased risk of RDS (OR = 3.264, p = .001, 95% CI = 1.597-6.672 and OR = 5.222, p < .001, 95% CI = 2.165-12.597, respectively); while VDR FokI showed no association with RDS. In multivariate logistic regression analysis, variant TaqI genotype increased risk of RDS (p = 0.001, OR = 3.464, 95% CI = 1.655-7.251) independent of gestational age, birth weight and gender. 25-OHD levels in the RDS group were significantly lower compared with those in without the RDS group (p = .002). Serum 25-OHD levels were not significantly different among the different FokI and TaqI genotypes in RDS group.Conclusions: This is the first report of association of VDR polymorphism with RDS development in preterm neonates. Current study suggests that VDR TaqI polymorphism may be involved in predisposition to RDS in premature neonates. Further studies are needed to assess the contribution of vitamin D and VDR signaling to the pathogenesis RDS.

No effect of prenatal vitamin D deficiency on autism-relevant behaviours in multiple inbred strains of mice

Autism Spectrum Disorders (ASD) is a group of neurodevelopmental disorders commonly characterised by verbal and non-verbal communication deficits, impaired social interaction and repetitive, stereotypic behaviours. The aetiology of ASD is most likely a combination of genetic and environmental factors. Epidemiological evidence suggests that prenatal vitamin D deficiency is associated with an increased incidence of ASD. The overall aim of this study was to investigate prenatal vitamin D deficiency on ASD-related behavioural phenotypes in multiple inbred strains of mice. We included two commonly used inbred mouse strains (C57BL/6J and BALB/c) as well as inbred BTBR mice, which show ASD-related behaviours, such as excessive self-grooming, hyperlocomotion, social interaction deficits and altered communication. We also studied the effect of prenatal vitamin D deficiency in a fourth strain; an F1 cross of C57BL/6J x BTBR mice, which have a partial BTBR phenotype. To implement prenatal vitamin D deficiency, female mice were placed on vitamin D deplete diets for ten weeks, including mating and gestation, until littering, when all dams were switched to the control diet. Behavioural symptoms related to ASD were measured, including isolation-induced ultrasonic vocalisations to measure communication, the three-chambered social interaction task to observe social interaction, the open field test to examine hyperlocomotion, assessment of grooming and rearing behaviour and finally the active place avoidance task to observe spatial learning and memory in response to a mild foot shock. Prenatal vitamin D deficiency had a negative impact on preference for social novelty in C57BL/6J mice, despite similar vocalisation phenotypes, and prenatal vitamin D-deficient F1 mice were found to be hypolocomotive in the open field test yet performed better on the active place avoidance task. Despite clear differences between strains, there were no other consistent significant main effects of maternal diet on the behaviour of the offspring. Vitamin D deficiency has been implicated as a risk factor for ASD and these data show that there is greater variation between different inbred strains in ASD-related behaviour, suggesting that prenatal vitamin D deficiency is not sufficient to recapitulate an ASD phenotype in multiple inbred strains of mice.

The impact of vitamin D on fetal and neonatal lung maturation. A systematic review

Respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD) are major complications to preterm birth. Hypovitaminosis D is prevalent in pregnancy. We systematically reviewed the evidence of the impact of vitamin D on lung development, surfactant synthesis, RDS, and BPD searching PubMed, Embase, and Cochrane databases with the terms vitamin D AND (surfactant OR lung maturation OR lung development OR respiratory distress syndrome OR fetal lung OR prematurity OR bronchopulmonary dysplasia). Three human studies, ten animal studies, two laboratory studies, and one combined animal and laboratory study were included. Human evidence was sparse, allowing no conclusions. BPD was not associated with vitamin D receptor polymorphism in a fully adjusted analysis. Animal and laboratory studies showed substantial positive effects of vitamin D on the alveolar type II cell, fibroblast proliferation, surfactant synthesis, and alveolarization. These data support the hypothesis of hypovitaminosis D as a frequent, modifiable risk factor of RDS and BPD, which should be tested in randomized controlled trials on pregnant women, those with threatening preterm delivery, or in the preterm neonates. Future experimental and human studies should aim to identify optimal time windows, vitamin D doses, and cut-off levels for 25-hydroxyvitamin D in interventions against RDS, BPD, and later adverse respiratory outcomes.

Vitamin D and its receptor during late development

Expression of the vitamin D receptor (VDR) is widespread but may vary depending on the developmental stage of the animal, and therefore may differentially influence phenotypic function. Thus, the major role of the 1,25-dihydroxyvitamin D [1,25(OH)2D]/VDR system is to regulate mineral and skeletal homeostasis, although mainly after birth. Post-natally, under conditions of low dietary calcium, the 1,25(OH)2D/VDR system enhances intestinal transcellular transport of calcium and possibly paracellular calcium entry by regulating genes that are critical for these functions. This process, by providing adequate calcium, is essential for normal development of the skeletal growth plate and mineralization of bone. Furthermore, blood calcium and phosphorus homeostasis is maintained by an interplay between feedback loops of the 1,25(OH)2D/VDR system with parathyroid hormone and with fibroblast-growth factor (FGF) 23 respectively. The 1,25(OH)2D/VDR system can also modulate the expression of genes involved in both bone formation and resorption post-natally. Ligand independent activity of the VDR normally influences mammalian hair cycling after birth by potentiating Wnt and bone morphogenetic protein (BMP) signaling. Nevertheless ligand bound VDR may also modulate epidermal cell proliferation/differentiation by regulating the balance in function of c-MYC and its antagonist the transcriptional repressor MAD1/MXD1 in skin epithelia. The 1,25(OH)2D/VDR system can also modulate innate immune cells and promote a more tolerogenic immunological status and may therefore influence inflammation and the development of autoimmunity; whether this impacts the fetus is uncertain. This article is part of a Special Issue entitled: Nuclear receptors in animal development.

Is there convincing biological or behavioral evidence linking vitamin D deficiency to brain dysfunction?

Vitamin D insufficiency is common in the United States; the elderly and African-Americans are at particularly high risk of deficiency. This review, written for a broad scientific readership, presents a critical overview of scientific evidence relevant to a possible causal relationship between vitamin D deficiency and adverse cognitive or behavioral effects. Topics discussed are 1) biological functions of vitamin D relevant to cognition and behavior; 2) studies in humans and rodents that directly examine effects of vitamin D inadequacy on cognition or behavior; and 3) immunomodulatory activity of vitamin D relative to the proinflammatory cytokine theory of cognitive/behavioral dysfunction. We conclude there is ample biological evidence to suggest an important role for vitamin D in brain development and function. However, direct effects of vitamin D inadequacy on cognition/behavior in human or rodent systems appear to be subtle, and in our opinion, the current experimental evidence base does not yet fully satisfy causal criteria. Possible explanations for the apparent inconsistency between results of biological and cognitive/behavioral experiments, as well as suggested areas for further research are discussed. Despite residual uncertainty, recommendations for vitamin D supplementation of at-risk groups, including nursing infants, the elderly, and African-Americans appear warranted to ensure adequacy.

Effect of prenatal vitamin D (calcitriol) exposure on the growth and development of the prostate

BACKGROUND

We previously found that in the absence of testosterone (T), calcitriol promotes proliferation of normal prostatic stroma, while in the presence of T, it has a differentiating effect on prostatic epithelium. The present study was conducted to determine the effect of calcitriol exposure in utero on the postnatal development of the normal prostate.

METHODS

Pregnant rats were injected subcutaneously with either 1.25 microg of calcitriol or vehicle alone on alternate days till delivery. Calcitriol-exposed and control pups were sacrificed at age 25 days (prepuberty), 63 days (postpuberty), or 102 days (adults), and their prostates and seminal vesicles were harvested and weighed.

RESULTS

Pups prenatally exposed to calcitriol and sacrificed before puberty (25 days) had a 35% greater mean prostatic weight than controls (0.0314 vs. 0.0422 g, P < 0.007), and calcitriol-exposed adult rats (102 days) had a 68% greater mean prostatic weight than controls (0.1365 vs. 0.2304 g, P < 0.005). No differences were observed in seminal vesicle weights, and in serum calcium and testosterone levels. A disproportionately high mortality rate from sudden death (71%) was observed at puberty in uncastrated male rats prenatally exposed to calcitriol.

CONCLUSIONS

These findings suggest that high-dose calcitriol exposure in utero may uniquely influence subsequent prostatic growth. Nonandrogenic steroids such as calcitriol may also be involved in genetic imprinting of the prostate.