Vitamin D constrains inflammation by modulating the expression of key genes on Chr17q12-21.1.

Vitamin D possesses immunomodulatory functions and vitamin D deficiency has been associated with the rise in chronic inflammatory diseases, including asthma (Litonjua and Weiss, 2007). Vitamin D supplementation studies do not provide insight into the molecular genetic mechanisms of vitamin D-mediated immunoregulation. Here, we provide evidence for vitamin D regulation of two human chromosomal loci, Chr17q12-21.1 and Chr17q21.2, reliably associated with autoimmune and chronic inflammatory diseases. We demonstrate increased vitamin D receptor (Vdr) expression in mouse lung CD4+ Th2 cells, differential expression of Chr17q12-21.1 and Chr17q21.2 genes in Th2 cells based on vitamin D status and identify the IL-2/Stat5 pathway as a target of vitamin D signaling. Vitamin D deficiency caused severe lung inflammation after allergen challenge in mice that was prevented by long-term prenatal vitamin D supplementation. Mechanistically, vitamin D induced the expression of the Ikzf3-encoded protein Aiolos to suppress IL-2 signaling and ameliorate cytokine production in Th2 cells. These translational findings demonstrate mechanisms for the immune protective effect of vitamin D in allergic lung inflammation with a strong molecular genetic link to the regulation of both Chr17q12-21.1 and Chr17q21.2 genes and suggest further functional studies and interventional strategies for long-term prevention of asthma and other autoimmune disorders.

Prenatal vitamin D supplementation to prevent childhood asthma: 15-year results from the Vitamin D Antenatal Asthma Reduction Trial (VDAART).

This article provides an overview of the findings obtained from the Vitamin D Antenatal Asthma Reduction Trial (VDAART) spanning a period of 15 years. The review covers various aspects, including the trial's rationale, study design, and initial intent-to-treat analyses, as well as an explanation of why those analyses did not achieve statistical significance. Additionally, the article delves into the post hoc results obtained from stratified intent-to-treat analyses based on maternal vitamin D baseline levels and genotype-stratified analyses. These results demonstrate a statistically significant reduction in asthma among offspring aged 3 and 6 years when comparing vitamin D supplementation (4400 IU/d) to the standard prenatal multivitamin with vitamin D (400 IU/d). Furthermore, these post hoc analyses found that vitamin D supplementation led to a decrease in total serum IgE levels and improved lung function in children compared to those whose mothers received a placebo alongside the standard prenatal multivitamin with vitamin D. Last, the article concludes with recommendations regarding the optimal dosing of vitamin D for pregnant women to prevent childhood asthma as well as suggestions for future trials in this field.

The Impact of Baseline 25-Hydroxyvitamin D Level and Gestational Age on Prenatal Vitamin D Supplementation to Prevent Offspring Asthma or Recurrent Wheezing.

BACKGROUND: Prenatal vitamin D deficiency is associated with asthma or recurrent wheezing in offspring. However, evidence from randomized trials on the efficacy of vitamin D supplementation is inconclusive. OBJECTIVES: We aimed to examine the differential efficacy of prenatal vitamin D supplementation based on the maternal baseline vitamin D status and the starting time of supplementation to prevent early life asthma or recurrent wheezing. METHODS: We conducted a secondary analysis of the Vitamin D Antenatal Asthma Reduction Trial (VDAART), a randomized double-blind trial of prenatal vitamin D supplementation initiated at 10-18 weeks (wks) of gestation (4400 IU of intervention/day compared with 400 IU of placebo/day) to prevent offspring asthma or recurrent wheezing by the age of 6 years. We assessed the effect of modification of supplementation by maternal baseline vitamin D status at enrollment and the timing of initiation of supplementation. RESULTS: An inverse relationship was observed between maternal 25-hydroxyvitamin D (25(OH)D) levels at trial entry and 25(OH)D levels during late pregnancy (32-38 wks of gestation) in both supplementation arms (P < 0.001). Overall, supplementation efficacy was not dependent on the maternal baseline 25(OH)D status. However, a trend toward the reduction of asthma or recurrent wheezing was observed across the baseline groups in the intervention arm (P = 0.01), with the greatest reduction observed in the most severely vitamin D-deficient women (25(OH)D < 12 ng/mL; adjusted odds ratio [aOR] = 0.48; confidence interval [CI]: 0.17, 1.34). Gestational age at trial enrollment modified supplementation efficacy, showing a greater reduction of offspring asthma or recurrent wheezing with earlier intervention during pregnancy (aOR = 0.85; CI = 0.76, 0.95), particularly in women who were 9-12 wk pregnant (aOR = 0.45; CI = 0.24, 0.82). CONCLUSIONS: Pregnant women with severe vitamin D deficiency show the greatest 25(OH)D improvement because of supplementation. In these women, a vitamin D dose of 4400 IU might have a preventive role in the development of early life offspring asthma or recurrent wheezing. Gestational age is suggested to modify the efficacy of prenatal vitamin D supplementation, showing the highest beneficial effect if supplementation is started during the first trimester of pregnancy. This study is an ancillary analysis from the VDAART, which is registered in ClinicalTrials.gov as NCT00902621.

Maternal vitamin D status modifies the effects of early life tobacco exposure on child lung function.

BACKGROUND: Prior studies suggest that vitamin D may modify the effects of environmental exposures; however, none have investigated gestational vitamin D and cumulative tobacco smoke exposure (TSE) throughout pregnancy and early life. OBJECTIVES: This study investigated the effects of early life TSE on child lung function and the modulatory effects of gestational vitamin D on this association. METHODS: The VDAART (Vitamin D Antenatal Asthma Reduction Trial) recruited nonsmoking pregnant women and followed the mother-child pairs to age 6 years. TSE was assessed with questionnaires and plasma cotinine measurements in the mothers (10-18 and 32-38 gestational weeks) and children (1, 3, and 6 years). Cumulative TSE was calculated from the repeated cotinine measurements. 25-hydroxyvitamin D (25[OH]D) levels were measured at 10-18 and 32-38 gestational weeks. Lung function was assessed at 6 years with spirometry and impulse oscillometry. RESULTS: Of the 476 mother-child pairs, 205 (43%) had increased cotinine levels at ≥1 time point. Cumulative TSE was associated with decreased FEV1 (ß = -0.043 L, P = .018) and increased respiratory resistance at 5 Hz (R5; ß = 0.060 kPa/L/s, P = .002). This association persisted in subjects with insufficient (<30 ng/mL) 25(OH)D levels throughout pregnancy (ß = 0.077 kPa/L/s, P = .016 for R5) but not among those with sufficient levels throughout pregnancy. CONCLUSIONS: Cumulative TSE from pregnancy to childhood is associated with dose- and duration-dependent decreases in child lung function at 6 years even in the absence of reported maternal smoking. Gestational vitamin D may modulate this effect and have therapeutic potential for minimizing the adverse effect of TSE on lung throughout early life. RANDOMIZED TRIAL: Maternal Vitamin D Supplementation to Prevent Childhood Asthma (VDAART); clinicaltrials.gov identifier: NCT00920621.

The Association of Prenatal Vitamin D Sufficiency With Aeroallergen Sensitization and Allergic Rhinitis in Early Childhood.

BACKGROUND: The role of prenatal vitamin D sufficiency and supplementation in the development of childhood aeroallergen sensitization and allergic rhinitis remains uncertain. OBJECTIVE: To describe the association of prenatal vitamin D sufficiency with childhood allergic outcomes in participants of the Vitamin D Antenatal Asthma Reduction Trial, a randomized controlled trial of prenatal vitamin D supplementation. METHODS: We included 414 mother-offspring pairs with offspring aeroallergen sensitization data available at age 6 years in this analysis. We examined the association between prenatal vitamin D sufficiency status, based on vitamin D levels measured in the first and third trimesters, or vitamin D supplementation treatment assignment with the outcomes of aeroallergen sensitization, parent-reported clinical allergic rhinitis, parent-reported clinical allergic rhinitis with aeroallergen sensitization, food sensitization, any sensitization, eczema, and total IgE at ages 3 and 6 years. RESULTS: Compared with early and late insufficiency, early prenatal vitamin D insufficiency with late sufficiency was associated with reduced development of clinical allergic rhinitis with aeroallergen sensitization at 3 years (adjusted odds ratio [aOR] = 0.34; 95% confidence interval [CI], 0.13-0.82; P = .02) and 6 years (aOR = 0.54; 95% CI, 0.29-0.98; P = .05). At 6 years, clinical allergic rhinitis with sensitization was significantly decreased in offspring whose mothers received high-dose vitamin D (aOR = 0.54; 95% CI, 0.32-0.91; P = .02) compared with offspring whose mothers who received low-dose vitamin D. Associations of prenatal vitamin D with aeroallergen sensitization were strengthened among children who also developed asthma or who had a maternal history of atopy. CONCLUSIONS: Among mothers with first-trimester vitamin D insufficiency, we detected a protective effect of third-trimester prenatal vitamin D sufficiency on the development of clinical allergic rhinitis with aeroallergen sensitization at ages 3 and 6 years.

High-dose vitamin D during pregnancy and pathway gene polymorphisms in prevention of offspring persistent wheeze.

BACKGROUND: Randomized controlled trials (RCTs) suggest a protective effect of high-dose vitamin D supplementation in pregnancy on offspring risk of persistent wheeze, but only in some individuals, which might be explained by variations in vitamin D pathway genes. This study aimed to investigate the effect of vitamin D supplementation by maternal and offspring vitamin D receptor (VDR) genotype and GC genotype, encoding vitamin D binding protein (VDBP), in two RCTs. METHODS: In the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC2010 ) RCT, we analyzed the effect of high-dose vitamin D during pregnancy on the risk of persistent wheeze age 0-3 years by variants in single nucleotide polymorphisms (SNPs) in VDR (rs1544410, rs2228570, rs7975128, rs7975232) and GC (rs4588, rs7041). Replication was sought in the Vitamin D Antenatal Asthma Reduction Trial (VDAART). RESULTS: In COPSAC2010 , VDR SNP rs1544410 influenced the effect of high-dose vitamin D: maternal Pinteraction  = .049 and child Pinteraction  = .001, with the largest effect in offspring from mothers with TT genotype: hazard ratio (95% CI), 0.26 (0.10-0.68), P = .006, and no effect among CT or CC genotypes: 0.85 (0.48-1.51), P = .58 and 0.94 (0.47-1.89), P = .87, respectively. However, these findings were not replicated in VDAART. There was no significant effect modification from maternal or offspring GC genotype in either COPSAC2010 or VDAART: all Pinteraction  ≥ .17. CONCLUSIONS: We found that the effect of high-dose vitamin D supplementation during pregnancy on offspring risk of persistent wheeze was significantly influenced by VDR genotype in the COPSAC2010 RCT, but not VDAART, which may be due to population differences.

Effect of early and late prenatal vitamin D and maternal asthma status on offspring asthma or recurrent wheeze.

BACKGROUND: Childhood asthma developmental programming is complex. Maternal asthma is a strong risk factor for childhood asthma, whereas vitamin D (VD) has emerged as a modifiable prenatal exposure. OBJECTIVE: Our aim was to examine the combined effect of early and late prenatal VD status in during pregnancies in women with and without asthma on childhood asthma or recurrent wheeze development. METHODS: We conducted a cohort study using prospectively collected data from the Vitamin D Antenatal Asthma Reduction Trial, a randomized, double-blinded, placebo-controlled VD supplementation trial in pregnant women at high risk of offspring asthma (N = 806 mother-offspring pairs). 25-Hydroxyvitamin-D (25(OH)D) level was measured in early and late pregnancy. Our main exposure was an ordered variable representing early and late prenatal VD sufficiency (25(OH)D level ≥ 30 ng/mL) status during pregnancy in women with and without asthma. The primary outcome was offspring with asthma or recurrent wheeze by age 3 years. We also examined the effect of prenatal VD level on early life asthma or recurrent wheeze progression to active asthma at age 6 years. RESULTS: Among mothers with asthma versus among mothers with early and late prenatal VD insufficiency, those with early or late VD sufficiency (adjusted odds ratio = 0.56; 95% CI = 0.31-1.00) or early and late VD sufficiency (adjusted odds ratio = 0.36; 95% CI = 0.15-0.81) had a lower risk of offspring with asthma or recurrent wheeze by age 3 years (Pfor trend = .008). This protective trend was reiterated in asthma or recurrent wheeze progression to active asthma from age 3 to 6 years (Pfor trend = .04). CONCLUSION: This study implies a protective role for VD sufficiency throughout pregnancy, particularly in attenuating the risk conferred by maternal asthma on childhood asthma or recurrent wheeze development.

Vitamin D Sufficiency Has a Limited Effect on Placental Structure and Pathology: Placental Phenotypes in the VDAART Trial.

Vitamin D insufficiency during pregnancy is widespread. The effects of active vitamin D on the human placenta in vivo are unknown. We test the hypotheses that 25(OH)D sufficiency (arbitrarily defined as 25(OH)D ≥32 ng/mL) modulates placental structure and function in vivo in a population of women whose offspring are at risk for childhood asthma, and that placental pathology is more common in offspring that evolve asthma at age 3. Pregnant volunteers in the St. Louis, MO, cohort of the Vitamin D Antenatal Asthma Reduction Trial (VDAART, NIH grant #HL091528) participated in a nested case-control study and consented for the study of placentas after delivery. Maternal concentrations of 25(OH)D were measured at trial entry and in the third trimester. The histopathology of the placentas from women with sufficient 25(OH)D, versus insufficient, showed no clinically significant differences, but morphometry revealed villi of women with sufficient third-trimester 25(OH)D had a higher villous surface density. Notably, analyses of transcripts, extracted from formalin-fixed paraffin-embedded specimens, revealed higher expression of INTS9, vWF, MACC1, and ARMS2, and diminished expression of the CNTN5 genes in the insufficient group. A larger proportion of placentas showed chronic chorioamnionitis in offspring with versus without asthma at age 3. These findings suggest that maternal 25(OH)D insufficiency has a limited effect on human placental villous histopathology and morphometry, but attenuates a small number of placental gene expression profiles in this selected population. The association of placental chronic chorioamnionitis and offspring asthma is worthy of further study.

Six-Year Follow-up of a Trial of Antenatal Vitamin D for Asthma Reduction.

BACKGROUND: We previously reported the results of a trial of prenatal vitamin D supplementation to prevent asthma and recurrent wheeze in young children, which suggested that supplementation provided a protective effect at the age of 3 years. We followed the children through the age of 6 years to determine the course of asthma and recurrent wheeze. METHODS: In this follow-up study, investigators and participants remained unaware of the treatment assignments through the children's sixth birthday. We aimed to determine whether, when maternal levels of 25-hydroxyvitamin D were taken into account, children born to mothers who had received 4400 IU of vitamin D3 per day during pregnancy (vitamin D group) would have a lower incidence of asthma and recurrent wheeze at the age of 6 years than would those born to mothers who had received 400 IU of vitamin D3 per day (control group). Time-to-event methods were used to compare the treatment groups with respect to time to the onset of asthma or recurrent wheeze. Multivariate methods were used to compare longitudinal measures of lung function between the treatment groups. RESULTS: There was no effect of maternal vitamin D supplementation on asthma and recurrent wheeze in either an intention-to-treat analysis or an analysis with stratification according to the maternal 25-hydroxyvitamin D level during pregnancy. There was no effect of prenatal vitamin D supplementation on most of the prespecified secondary outcomes. We found no effects of prenatal supplementation on spirometric indexes. Although there was a very small effect on airway resistance as measured by impulse oscillometry, this finding was of uncertain significance. CONCLUSIONS: Vitamin D supplementation during the prenatal period alone did not influence the 6-year incidence of asthma and recurrent wheeze among children who were at risk for asthma. (Funded by the National Heart, Lung, and Blood Institute; VDAART ClinicalTrials.gov number, NCT00920621.).

Impact of parental asthma, prenatal maternal asthma control, and vitamin D status on risk of asthma and recurrent wheeze in 3-year-old children.

BACKGROUND: While familial clustering of asthma is known, few studies have reported on the relative roles of paternal and maternal asthma and the role of maternal asthma control in pregnancy on the risk for asthma in the child. OBJECTIVE: We aimed to investigate the relative roles of paternal asthma, maternal asthma, and maternal asthma control during pregnancy on the risk of asthma or recurrent wheeze in 3-year-old children and how prenatal and cord blood vitamin D status might affect this risk. METHODS: Data from 806 women, their partners (biologic fathers of the infants), and their children participated in the Vitamin D Antenatal Asthma Reduction Trail (VDAART, clinicaltrials.gov identification number NCT00920621) were used for this cohort analysis. The parental report of physician-diagnosed asthma or recurrent wheeze in offspring was the main outcome. Weibull regression models for interval-censored event times were used to estimate the main variables of interests and additional covariates on the outcome. RESULTS: The highest risk was observed among children with both parents being asthmatic relative to non-asthmatic parents (aHR = 2.30, 95% CI: 1.35-3.84), and less so if only the mother was asthmatic (aHR = 1.70, 95% CI: 1.17-2.40). In the subset of children born to asthmatic mothers, the risk for asthma was higher in those who were born to mothers whose asthma was uncontrolled (aHR = 1.60, 95% CI: 1.02-2.54). Children whose mothers had sufficient vitamin D status (25Hydroxyvitamin D ≥ 30 ng/mL) at early and late pregnancy and had cord blood vitamin D sufficiency demonstrated a lower risk of asthma/recurrent wheeze than children who had insufficient cord blood vitamin D status at birth (aHR = 0.47, 95% CI: 0.27-0.83). CONCLUSION AND CLINICAL RELEVANCE: Careful attention to maternal asthma control, monitoring vitamin D status, and correcting insufficiency at early pregnancy and maintaining the sufficiency status throughout pregnancy have potential preventive roles in offspring asthma or recurrent wheeze.

Vitamin D prenatal programming of childhood metabolomics profiles at age 3 y.

Background: Vitamin D deficiency is implicated in a range of common complex diseases that may be prevented by gestational vitamin D repletion. Understanding the metabolic mechanisms related to in utero vitamin D exposure may therefore shed light on complex disease susceptibility.Objective: The goal was to analyze the programming role of in utero vitamin D exposure on children's metabolomics profiles.Design: First, unsupervised clustering was done with plasma metabolomics profiles from a case-control subset of 245 children aged 3 y with and without asthma from the Vitamin D Antenatal Asthma Reduction Trial (VDAART), in which pregnant women were randomly assigned to vitamin D supplementation or placebo. Thereafter, we analyzed the influence of maternal pre- and postsupplement vitamin D concentrations on cluster membership. Finally, we used the metabolites driving the clustering of children to identify the dominant metabolic pathways that were influential in each cluster.Results: We identified 3 clusters of children characterized by 1) high concentrations of fatty acids and amines and low maternal postsupplement vitamin D (mean ± SD; 27.5 ± 11.0 ng/mL), 2) high concentrations of amines, moderate concentrations of fatty acids, and normal maternal postsupplement vitamin D (34.0 ± 14.1 ng/mL), and 3) low concentrations of fatty acids, amines, and normal maternal postsupplement vitamin D (35.2 ± 15.9 ng/mL). Adjusting for sample storage time, maternal age and education, and both child asthma and vitamin D concentration at age 3 y did not modify the association between maternal postsupplement vitamin D and cluster membership (P = 0.0014). Maternal presupplement vitamin D did not influence cluster membership, whereas the combination of pre- and postsupplement concentrations did (P = 0.03).Conclusions: Young children can be clustered into distinct biologically meaningful groups by their metabolomics profiles. The clusters differed in concentrations of inflammatory mediators, and cluster membership was influenced by in utero vitamin D exposure, suggesting a prenatal programming role of vitamin D on the child's metabolome. This trial was registered at clinicaltrials.gov as NCT00920621.

Early pregnancy vitamin D status and risk of preeclampsia.

BACKGROUND: Low vitamin D status in pregnancy was proposed as a risk factor of preeclampsia. METHODS: We assessed the effect of vitamin D supplementation (4,400 vs. 400 IU/day), initiated early in pregnancy (10-18 weeks), on the development of preeclampsia. The effects of serum vitamin D (25-hydroxyvitamin D [25OHD]) levels on preeclampsia incidence at trial entry and in the third trimester (32-38 weeks) were studied. We also conducted a nested case-control study of 157 women to investigate peripheral blood vitamin D-associated gene expression profiles at 10 to 18 weeks in 47 participants who developed preeclampsia. RESULTS: Of 881 women randomized, outcome data were available for 816, with 67 (8.2%) developing preeclampsia. There was no significant difference between treatment (N = 408) or control (N = 408) groups in the incidence of preeclampsia (8.08% vs. 8.33%, respectively; relative risk: 0.97; 95% CI, 0.61-1.53). However, in a cohort analysis and after adjustment for confounders, a significant effect of sufficient vitamin D status (25OHD ≥30 ng/ml) was observed in both early and late pregnancy compared with insufficient levels (25OHD <30 ng/ml) (adjusted odds ratio, 0.28; 95% CI, 0.10-0.96). Differential expression of 348 vitamin D-associated genes (158 upregulated) was found in peripheral blood of women who developed preeclampsia (FDR <0.05 in the Vitamin D Antenatal Asthma Reduction Trial [VDAART]; P < 0.05 in a replication cohort). Functional enrichment and network analyses of this vitamin D-associated gene set suggests several highly functional modules related to systematic inflammatory and immune responses, including some nodes with a high degree of connectivity. CONCLUSIONS: Vitamin D supplementation initiated in weeks 10-18 of pregnancy did not reduce preeclampsia incidence in the intention-to-treat paradigm. However, vitamin D levels of 30 ng/ml or higher at trial entry and in late pregnancy were associated with a lower risk of preeclampsia. Differentially expressed vitamin D-associated transcriptomes implicated the emergence of an early pregnancy, distinctive immune response in women who went on to develop preeclampsia. TRIAL REGISTRATION: ClinicalTrials.gov NCT00920621. FUNDING: Quebec Breast Cancer Foundation and Genome Canada Innovation Network. This trial was funded by the National Heart, Lung, and Blood Institute. For details see Acknowledgments.

The Role of Vitamin D in the Transcriptional Program of Human Pregnancy.

BACKGROUND: Patterns of gene expression of human pregnancy are poorly understood. In a trial of vitamin D supplementation in pregnant women, peripheral blood transcriptomes were measured longitudinally on 30 women and used to characterize gene co-expression networks. OBJECTIVE: Studies suggest that increased maternal Vitamin D levels may reduce the risk of asthma in early life, yet the underlying mechanisms have not been examined. In this study, we used a network-based approach to examine changes in gene expression profiles during the course of normal pregnancy and evaluated their association with maternal Vitamin D levels. DESIGN: The VDAART study is a randomized clinical trial of vitamin D supplementation in pregnancy for reduction of pediatric asthma risk. The trial enrolled 881 women at 10-18 weeks of gestation. Longitudinal gene expression measures were obtained on thirty pregnant women, using RNA isolated from peripheral blood samples obtained in the first and third trimesters. Differentially expressed genes were identified using significance of analysis of microarrays (SAM), and clustered using a weighted gene co-expression network analysis (WGCNA). Gene-set enrichment was performed to identify major biological pathways. RESULTS: Comparison of transcriptional profiles between first and third trimesters of pregnancy identified 5839 significantly differentially expressed genes (FDR<0.05). Weighted gene co-expression network analysis clustered these transcripts into 14 co-expression modules of which two showed significant correlation with maternal vitamin D levels. Pathway analysis of these two modules revealed genes enriched in immune defense pathways and extracellular matrix reorganization as well as genes enriched in notch signaling and transcription factor networks. CONCLUSION: Our data show that gene expression profiles of healthy pregnant women change during the course of pregnancy and suggest that maternal Vitamin D levels influence transcriptional profiles. These alterations of the maternal transcriptome may contribute to fetal immune imprinting and reduce allergic sensitization in early life. TRIAL REGISTRATION: clinicaltrials.gov NCT00920621.