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

Vitamin D status of very low birth weight infants at birth and the effects of generally recommended supplementation on their vitamin D levels at discharge

Purpose: To evaluate vitamin D status in mothers and their very low birth weight infants (VLBW) at birth (umbilical cord blood) and at discharge with currently recommended supplementation of vitamin D.Methods: Ninety-four infants with birth weight less than 1500 g completed the study. The total daily vitamin D intake was 800-1000 IU. We examined 25-hydroxyvitamin-D [25(OH)D] levels in maternal serum before labor, in cord blood, and in infants' serum at discharge.Results: Median (IQR) serum 25(OH)D was 21 (14-36) nmol/l [8 (6-15) ng/ml] in cord blood, and 46 (37-60) nmol/l [18 (15-24) ng/ml] at discharge. Serum 25(OH)D was <50 nmol/L in 71.3% of mothers, in 91.5% of cord blood samples, and in almost 60% of preterm newborns at discharge (after 8 weeks of supplementation). Serum 25(OH)D was <75 nmol/L in 88.3% of mothers, in 97.9% of cord blood samples, and in 91.4% of preterm newborns at discharge.Conclusions: In our cohort, we found that due to the very high prevalence of 25(OH)D deficiency among mothers, the current generally recommended dose of vitamin D (800-1000 IU per day) for VLBW infants was unable to improve vitamin D levels above the desired 50 or even 75 nmol/L before discharge.

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.

Modulators of inflammation in Bronchopulmonary Dysplasia

Over 50 years after its first description, Bronchopulmonary Dysplasia (BPD) remains a devastating pulmonary complication in preterm infants with respiratory failure and develops in 30-50% of infants less than 1000-gram birth weight. It is thought to involve ventilator- and oxygen-induced damage to an immature lung that results in an inflammatory response and ends in aberrant lung development with dysregulated angiogenesis and alveolarization. Significant morbidity and mortality are associated with this most common chronic lung disease of childhood. Thus, any therapies that decrease the incidence or severity of this condition would have significant impact on morbidity, mortality, human costs, and healthcare expenditure. It is clear that an inflammatory response and the elaboration of growth factors and cytokines are associated with the development of BPD. Numerous approaches to control the inflammatory process leading to the development of BPD have been attempted. This review will examine the anti-inflammatory approaches that are established or hold promise for the prevention or treatment of BPD.

The Role of Vitamin D in Fertility and during Pregnancy and Lactation: A Review of Clinical Data

Vitamin D deficiency is common and there exists a huge gap between recommended dietary vitamin D intakes and the poor vitamin D supply in the general population. While vitamin D is important for musculoskeletal health, there are accumulating data suggesting that vitamin D may also be important for fertility, pregnancy outcomes and lactation. Significant changes in vitamin D metabolism during pregnancy such as increased production of the “active vitamin D hormone” calcitriol support the important role of vitamin D in this setting. Observational studies show that vitamin D deficiency is a risk marker for reduced fertility and various adverse pregnancy outcomes and is associated with a low vitamin D content of breast milk. Meta-analyses of randomized controlled trials (RCTs) document that physiological vitamin D supplementation during pregnancy is safe and improves vitamin D and calcium status, thereby protecting skeletal health. Although certain RCTs and/or meta-analyses reported some other beneficial effects, it is still not clear whether vitamin D supplementation improves fertility or decreases the risk of adverse pregnancy outcomes such as low birth weight, pre-eclampsia and neonatal mortality, or reduces wheeze/asthma in the infants. Nevertheless, vitamin D supplementation in pregnant women is frequently required to achieve a sufficient vitamin D status as recommended by nutritional vitamin D guidelines. In this review, we provide an overview of systematic reviews, meta-analyses and large trials reporting clinical data on the role of vitamin D for fertility, pregnancy and lactation.

Updates on the Status of Vitamin D as a Risk Factor for Respiratory Distress Syndrome

To update the guidelines regarding vitamin D status in respiratory distress syndrome, we reviewed recent human and animal studies on the benefits of vitamin D in respiratory distress. We searched PubMed and ProQuest for studies on the use of vitamin D from 2009 to 2017. The common parameters in these studies included the use of lung tissue, phospholipids, blood, and plasma to assess the effects of vitamin D on respiratory syndrome. The metabolized form of vitamin D used in these studies was 1,25(OH)₂D₃ in animal studies and 25(OH)D in human studies. Vitamin D supplementation decreases the risk of respiratory distress syndrome, improves the quality of life, and is relatively effective and safe for preterm neonates as well as during lung maturation. However, although vitamin D supplementation may offer benefits for respiratory distress syndrome, the optimal dosing strategies for specific types of risk factors in the lungs must be clarified to confirm the therapeutic efficacy.

Vitamin A Deficiency and the Lung

Vitamin A (all-trans-retinol) is a fat-soluble micronutrient which together with its natural derivatives and synthetic analogues constitutes the group of retinoids. They are involved in a wide range of physiological processes such as embryonic development, vision, immunity and cellular differentiation and proliferation. Retinoic acid (RA) is the main active form of vitamin A and multiple genes respond to RA signalling through transcriptional and non-transcriptional mechanisms. Vitamin A deficiency (VAD) is a remarkable public health problem. An adequate vitamin A intake is required in early lung development, alveolar formation, tissue maintenance and regeneration. In fact, chronic VAD has been associated with histopathological changes in the pulmonary epithelial lining that disrupt the normal lung physiology predisposing to severe tissue dysfunction and respiratory diseases. In addition, there are important alterations of the structure and composition of extracellular matrix with thickening of the alveolar basement membrane and ectopic deposition of collagen I. In this review, we show our recent findings on the modification of cell-junction proteins in VAD lungs, summarize up-to-date information related to the effects of chronic VAD in the impairment of lung physiology and pulmonary disease which represent a major global health problem and provide an overview of possible pathways involved.

Serum level of vitamin D in preterm infants and its association with premature-related respiratory complications: a case-control study

Background and aim

Prematurity and related problems, especially respiratory distress, are one of the main challenges for neonatal medicine. The aim of this study was to compare vitamin D levels in preterm infants with, and those without respiratory distress.

Methods

This case-control study was conducted in Ghaem and Emam Reza Hospitals in Mashhad (Iran) from 2015 to 2016. In this study, we examined 160 preterm infants weighing less than 2000 grams and born at less than 34 weeks' gestation. Serum vitamin D levels were measured in preterm infants without- and those with respiratory distress, and their mothers. Neonatal characteristics, including age, sex, birth weight, gestational age, Apgar score and needs for oxygen, resuscitation, ventilation and surfactant were documented. The data were analyzed using SPSS version 16.0.

Results

Means serum level of maternal vitamin D in control and case groups were 16.66±14.29 ng/dl and 21.23±15.19 ng/dl, respectively (p=0.029). In addition, mean serum level of neonatal vitamin D in control and case groups were 11.69±8.66 ng/dl 17.9±12.55 ng/dl, respectively (p=0.001). Vitamin D levels in premature neonates without respiratory distress and their mothers were significantly different from other preterm neonates with respiratory distress (p=0.029). There was a direct correlation with neonatal and maternal vitamin D levels (r=0.713, p=0.001). The duration of hospitalization (p=0.001), gestational age (p=0.073), birth weight (p=0.001), one- and (p=0.001) five-minute (p=0.001) Apgar scores and head circumference (p=0.002) had significant relation with vitamin D levels in neonates. Death (12.5%) and pneumothorax (7.5%) were the main complications among cases with respiratory distress.

Conclusion

According to the results of present research, neonatal vitamin D levels have a significant association with respiratory distress syndrome and maternal vitamin D levels.

Vitamin D Enhances Alveolar Development in Antenatal Lipopolysaccharide-Treated Rats through the Suppression of Interferon-γ Production

Bronchopulmonary dysplasia (BPD) is characterized by the premature arrest of alveolar development. Antenatal exposure to inflammation inhibits lung morphogenesis, thereby increasing the risk for the development of BPD. Here, we investigated whether vitamin D (VitD) enhances alveolar development in antenatal lipopolysaccharide (LPS)-treated rats, which is a model for BPD. We used an established animal model of BPD, and random assignment to the control group, LPS group, or LPS with VitD group. Levels of interferon (IFN)-γ and interleukin-4 were detected by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay. IFN-γ producing CD8+ T cells were assessed by flow cytometry, and the methylation status of the VitD-response element (VDRE) was analyzed by bisulfite sequencing PCR. 25-hydroxyvitamin D levels were measured by liquid chromatography tandem mass spectrometry in maternal serum samples collected from 86 pregnant women in a prospective birth cohort enrolled from 2012 to 2013. Our results showed that VitD effectively alleviated the simplification of the lung alveolar structure in BPD rats and suppressed LPS-induced IFN-γ expression in the lung and spleen tissues. Further investigation revealed that VitD suppressed IFN-γ production in CD8+ T cells. Specifically, VitD increased the methylation percentage of the VDRE in the IFN-γ-promoter region and suppressed LPS-induced expression of IFN-γ. Additionally, we observed an association between maternal VitD exposure during pregnancy and neonatal IFN-γ levels in a prospective birth cohort, with a trend similar to that observed in the animal model. Our data suggested that supplementation of VitD could suppress IFN-γ production, resulting in improved alveolar development in an LPS-induced BPD rat model.

Vitamin D and IL-10 Deficiency in Preterm Neonates With Bronchopulmonary Dysplasia

Introduction: Vitamin D deficiency and inflammation are involved with bronchopulmonary dysplasia (BPD) in preterm neonates; however, the clinical evidence still remains scarce. We hypothesized that vitamin D and inflammatory cytokines may be risk factors for BPD in infants. Methods: Preterm infants born between 28 and 31 weeks' gestation were recruited between January 2016 and 2017. Blood samples were all collected at corresponding time points. Vitamin D was measured using an automatic biochemical analyzer, and inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-10) were measured using ELISA. Results: The baseline characteristics for preterm infants without BPD (non-BPD control, n = 20) or with BPD (n = 19) were similar. In the blood samples collected 24-h post birth, vitamin D was significantly reduced in the BPD neonates (non-BPD vs. BPD, 28.96 ± 3.404 vs. 17.99 ± 2.233 nmol/l, p = 0.0134). Inflammatory cytokines TNF-α, IL-1β, and IL-6 were comparable in both groups. The anti-inflammatory cytokine IL-10, however, was significantly decreased in 24-h blood samples from BPD preterm infants (non-BPD vs. BPD, 44.61 ± 10.48 vs. 11.64 ± 2.351 pg/ml, p = 0.0054). In the BPD infants with mild or moderate disease, vitamin D deficiency was quite similar. IL-10 deficiency, however, was more aggravated in the BPD infants with moderate disease. No changes in Vitamin D or cytokines (TNF-α, IL-1β, IL-6, and IL-10) were observed for blood samples collected 2 or 4 weeks after birth. Conclusion: In our pilot study, Vitamin D and IL-10 levels at 24-h of life were risk factors for the development of BPD in very preterm infants.

[Relationship between serum 25(OH)D levels at birth and respiratory distress syndrome in preterm infants]

OBJECTIVE

To investigate the relationship between serum 25-hydroxyvitamin D [25(OH)D] levels at birth and respiratory distress syndrome (RDS) in preterm infants.

METHODS

This retrospective study recruited preterm infants with gestational age of below 34 weeks who were born between January 2014 and December 2016. These preterm infants were divided into two groups: RDS (n=72) and control (n=40). Clinical data of the two groups were collected, including gestational age, birth weight, gender, delivery mode, Apgar scores at 1 minute and 5 minutes, incidence of maternal gestational diabetes mellitus, and use of prenatal steroid hormone. Peripheral blood samples were collected and 25(OH)D levels were measured by chemiluminescence immunoassay. The association between serum 25(OH)D levels at birth and RDS was analyzed by multivariate logistic regression.

RESULTS

Apgar scores at 1 minute and 5 minutes and serum 25(OH)D levels in the RDS group were significantly lower than those in the control group (P<0.05), while the rates of neonatal asphyxia and vitamin D deficiency were significantly higher than those in the control group (P<0.05). Multivariate logistic regression analysis showed that neonatal asphyxia (OR=2.633, 95%CI: 1.139-6.085) and vitamin D deficiency (OR=4.064, 95%CI: 1.625-10.165) were risk factors for RDS in preterm infants.

CONCLUSIONS

Vitamin D deficiency might be associated with increased risk of RDS in preterm infants. Reasonable vitamin D supplementation during pregnancy might reduce the incidence of RDS in preterm infants.

Effect of different doses of vitamin D supplementation on preterm infants - an updated meta-analysis

OBJECTIVE

Vitamin D deficiency (VDD) is common among infants, especially in preterm babies. There are some controversies over its use on body development, immune function and incidence of bronchopulmonary dysplasia (BPD).

METHODS

We systematically reviewed PubMed, Embase, and Cochrane databases for studies in English, and in Wanfang, VIP, and Cnki databases for Chinese studies (databases were last launched on 1 August 2016).

RESULTS

Twelve original random controlled studies (seven in English and five in Chinese) were included (1). There are no differences between high-dose (800-1000 IU/d) and low-dose (400 IU/d) groups on calcium, phosphorus, and 25(OH)D concentrations (p > .05). However, length gain and head circumference gain are significantly increased in the high-dose group (p < .05) (2). IL-2, Ig-A, and Ig-G levels are significant increased in the vitamin D supplementation group compared with the control group (p < .05) (3). With respect to BPD, there is no significant difference between the vitamin D supplementation group and the control group (p > .05).

CONCLUSIONS

In preterm infants, daily supplementation of vitamin D in doses of 800-1000 IU compared with 400 IU appears to be better not only in development but also in immune function. But clinical trials with a larger sample size are still needed.

Lung development, regeneration and plasticity: From disease physiopathology to drug design using induced pluripotent stem cells

Lungs have a complex structure composed of different cell types that form approximately 17 million airway branches of gas-delivering bronchioles connected to 500 million gas-exchanging alveoli. Airways and alveoli are lined by epithelial cells that display a low rate of turnover at steady-state, but can regenerate the epithelium in response to injuries. Here, we review the key points of lung development, homeostasis and epithelial cell plasticity in response to injury and disease, because this knowledge is required to develop new lung disease treatments. Of note, canonical signaling pathways that are essential for proper lung development during embryogenesis are also involved in the pathophysiology of most chronic airway diseases. Moreover, the perfect control of these interconnected pathways is needed for the successful differentiation of induced pluripotent stem cells (iPSC) into lung cells. Indeed, differentiation of iPSC into airway epithelium and alveoli is based on the use of biomimetics of normal embryonic and fetal lung development. In vitro iPSC-based models of lung diseases can help us to better understand the impaired lung repair capacity and to identify new therapeutic targets and new approaches, such as lung cell therapy.

[Association between serum 25(OH)D levels at birth and bronchopulmonary dysplasia in preterm infants]

OBJECTIVE

To assess the association between serum 25-hydroxyvitamin D [25(OH)D] levels at birth and bronchopulmonary dysplasia (BPD) in preterm infants.

METHODS

This study recruited preterm infants with gestational age of below 34 weeks who were born between January 2014 and December 2016. These preterm infants were classified into two groups: BPD and control. The association between serum 25(OH)D levels at birth and BPD was analyzed.

RESULTS

Serum 25(OH)D levels in the BPD group was significantly lower than those in the control group [(37±17 nmol/L vs 47±20 nmol/L; P<0.05), and the rate of vitamin D deficiency was significantly higher than those in the control group (90.2% vs 74.0%; P<0.05). The level of serum 25(OH)D was negatively correlated with the incidence of BPD (r=-0.201, P=0.001).

CONCLUSIONS

Vitamin D deficiency at birth may be associated with BPD in preterm infants, but need to be further studied by multivariate analysis.

Recent advances in our understanding of the mechanisms of late lung development and bronchopulmonary dysplasia

The objective of lung development is to generate an organ of gas exchange that provides both a thin gas diffusion barrier and a large gas diffusion surface area, which concomitantly generates a steep gas diffusion concentration gradient. As such, the lung is perfectly structured to undertake the function of gas exchange: a large number of small alveoli provide extensive surface area within the limited volume of the lung, and a delicate alveolo-capillary barrier brings circulating blood into close proximity to the inspired air. Efficient movement of inspired air and circulating blood through the conducting airways and conducting vessels, respectively, generates steep oxygen and carbon dioxide concentration gradients across the alveolo-capillary barrier, providing ideal conditions for effective diffusion of both gases during breathing. The development of the gas exchange apparatus of the lung occurs during the second phase of lung development-namely, late lung development-which includes the canalicular, saccular, and alveolar stages of lung development. It is during these stages of lung development that preterm-born infants are delivered, when the lung is not yet competent for effective gas exchange. These infants may develop bronchopulmonary dysplasia (BPD), a syndrome complicated by disturbances to the development of the alveoli and the pulmonary vasculature. It is the objective of this review to update the reader about recent developments that further our understanding of the mechanisms of lung alveolarization and vascularization and the pathogenesis of BPD and other neonatal lung diseases that feature lung hypoplasia.

Vitamin D in Asthma: Mechanisms of Action and Considerations for Clinical Trials

There is increasing interest in the therapeutic utility of vitamin D in asthma, which is supported by a significant body of evidence on epidemiologic associations between vitamin D insufficiency and worse asthma control. In support of a causal relationship, vitamin D beneficially modulates diverse immunologic pathways in heterogeneous asthma endotypes, regulating the actions of lymphocytes, mast cells, antigen-presenting cells, and structural cells to dampen excessive inflammatory responses. Allergic asthma is characterized by a failure of immune tolerance and the development of pathologic responses to inhaled aeroallergens, and vitamin D has been extensively shown to support immune regulation. Alarmin cytokines are increasingly implicated in nonallergic eosinophilic inflammation, which vitamin D also regulates. Steroid resistance and pathologic interleukin (IL)-17 responses are features of severe asthma, and vitamin D beneficially enhances the response to steroids in these individuals. Additionally, vitamin D enhances antimicrobial pathways, which is of relevance to infection-precipitated asthma exacerbations. These mechanisms support a role for vitamin D as secondary prevention to reduce exacerbations and inflammation in asthma. Similar mechanisms, and effects on fetal lung development, likely underlie a primary prevention therapeutic role in pregnancy for vitamin D to reduce the development of asthma in children. However, randomized controlled trials of variable design show inconsistent positive outcomes for vitamin D interventions in asthma. Increased understanding of the biological characteristics of vitamin D reveals methodological issues that might explain certain negative outcomes. Importantly, on systematic review of the trials to date, vitamin D is shown to be beneficial in asthma. The evidence discussed in this review supports the importance of optimizing vitamin D in holistic asthma care.

Vitamin D, high-sensitivity C-reactive protein, and airway hyperresponsiveness in infants with recurrent respiratory symptoms

BACKGROUND

Vitamin D insufficiency might be associated with biased T-cell responses resulting in inflammatory conditions such as atopy and asthma. Little is known about the role of vitamin D in low-grade systemic inflammation and airway hyperresponsiveness (AHR) in young children.

OBJECTIVE

To evaluate whether vitamin D insufficiency and increased serum high-sensitivity C-reactive protein (hs-CRP) are linked to AHR in symptomatic infants.

METHODS

Seventy-nine infants with recurrent or persistent lower respiratory tract symptoms underwent comprehensive lung function testing and a bronchial methacholine challenge test. In addition, skin prick tests were performed and serum 25-hydroxyvitamin D (S-25-OHD), hs-CRP, total immunoglobulin E, and blood eosinophil levels were determined.

RESULTS

S-25-OHD was lowest in infants with blood eosinophilia and AHR (n = 10) compared with those with eosinophilia only (n = 6) or AHR only (n = 50) or those with neither (n = 13; P = .035). Moreover, vitamin D insufficiency (S-25-OHD <50 nmol/L) was most common in infants with blood eosinophilia and AHR (P = .041). Serum hs-CRP was lower in infants with recurrent physician-diagnosed wheezing (P = .048) and in those with blood eosinophilia (P = .015) than in infants without these characteristics and was not associated with S-25-OHD or AHR. S-25-OHD levels were significantly lower (median 54 nmol/L) during the autumn-winter season than in the spring-summer season (median 63 nmol/L; P = .026).

CONCLUSION

Vitamin D insufficiency could underlie eosinophilia and AHR in infants with troublesome lung symptoms, whereas hs-CRP-mediated low-grade systemic inflammation is rare in early childhood wheezing.

S-25-hydroxyvitamin D and C3-epimers in pregnancy and infancy: An Odense Child Cohort study

BACKGROUND

Analysis of serum 25-hydroxyvitamin D (s-25(OH)D) may be complicated by the less active or in-active vitamin D metabolite C3-epi-25(OH)D₃ (C3-epimer). We aimed to explore the relationship between s-C3-epimer and s-25(OH)D and other determinants and describe the longitudinal course of the C3-epimer fraction in paired mother-child samples.

METHOD

S-25(OH)D and s-C3-epimer were estimated by liquid chromatography mass spectrometry in 290 mother-infant pairs from the population-based Odense Child Cohort. Longitudinal analyses were feasible in two subcohorts; B) early and late pregnancy, cord, three and 18months (n=132); and C) early and late pregnancy, delivery and cord (n=105).

RESULTS

Mean s-25(OH)D was 50.6-110.4nmol/L at the six time points. The mean C3-epimer fraction was 10.1% at three months, 1.1%-3.0% at the other time points. In multivariate analyses, the s-C3-epimer correlated with s-25(OH)D (all time points, p<0.001), and season, maternal and infant age and maternal vitamin D supplementation at some time points. The C3-epimer fraction fluctuated between adjacent time points. By cosinor analyses, a season-dependent sinusoidal pattern for s-25(OH)D and C3-epimer fraction was found and changes between adjacent time points depended on season (p<0.007 or trend). In early infancy, subtraction of the C3-epi-25(OH)D₃ from total s-25(OH)D resulted in reclassification of 8% of the children by use of the 75nmol/L cut off for s-25(OH)D.

CONLCUSION

The s-C3-epimer was independently correlated to s-25(OH)D, season, maternal vitamin D supplementation, maternal and infant age. The C3-epimer fraction was only of clinical importance in early infancy, where it could lead to misclassification of the vitamin D status.

Higher serum 25(OH)D concentrations are associated with improved FEV1 and FVC in adolescence

Vitamin D plays a role in the development of the immune system and the lung, as well as in airway remodelling. Therefore, this study investigated the association between serum 25-hydroxyvitamin D (25(OH)D) concentrations and spirometric lung function parameters at age 15 years.

In the German birth cohorts GINIplus and LISAplus, lung function testing by spirometry and 25(OH)D measurements were performed during the 15-year follow-up examinations. Valid lung function measurements pre- and/or post-bronchodilation and serum 25(OH)D concentrations, which were adjusted for the date of blood sampling to account for seasonal variability, were available for 2607 adolescents. Associations between 25(OH)D concentrations and spirometric parameters were analysed using generalised additive models adjusted for confounding factors.

Serum 25(OH)D concentrations were significantly associated with forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and FEV1/FVC measured before bronchodilation after adjustment for potential confounders: FEV1 increased by 10 mL (95% CI 2–17), FVC by 20 mL (95% CI 12–28) and FEV1/FVC decreased by 0.177% (95% CI −0.286 to −0.067) per 10 nmol·L−1 increase in 25(OH)D concentrations. Flow rates (forced expiratory flow rates at 25, 50 and 75% of exhaled FVC (FEF25, FEF50, FEF75) and mean flow rate between 25 and 75% of FVC (FEF25–75)) were not associated with vitamin D. Similar associations were observed for lung function parameters measured after bronchodilation.

Vitamin D concentrations are positively associated with volume-related lung function parameters pre- and post-bronchodilation, suggesting structural changes in peripheral airways.

Vitamin D deficiency: What does it mean for chronic obstructive pulmonary disease (COPD)? a compherensive review for pulmonologists

OBJECTIVES

Vitamin D deficiency and Chronic Obstructive Pulmonary Disease (COPD) are both under-recognized health problems, world-wide. Although Vitamin D has long been known for calcemic effects it also has less known noncalcemic effects. Recent data have shown that Vitamin D deficiency is highly prevalent in patients with COPD and correlates with forced expiratory volume in one second (FEV₁ ) and FEV₁ decline. The objective of this work was to review the current literature on vitamin D deficiency in relation with COPD.

DATA SOURCE

A literature search, using the words "vitamin D" and "COPD", was undertaken in Pubmed database.

RESULTS

The noncalcemic effects of vitamin D relating with COPD may be summarised as increasing antimicrobial peptide production, regulation of inflammatory response and airway remodelling. Vitamin D inhibits the production of several proinflammatory cytokines and leads to suppression Th1 and Th17 responses which may be involved in the pathogenesis of COPD. Vitamin D insufficiency may also contribute to chronic respiratory infections and airway colonization so returning vitamin D concentrations to an optimal range in patients with COPD might reduce bacterial load and concomitant exacerbations.Vitamin D is also important for COPD-related comorbodities such as osteoporosis, muscle weakness and cardiovascular diseases. Data about the effect of Vitamin D supplementation on those comorbidities in relation with COPD are been scarce.

CONCLUSION

Improving the blood level of Vitamin D into the desired range may have a beneficial effect bones and muscles, but more studies are needed to test to test that hypothesis.

Protective effect of vitamin D against hyperoxia-induced lung injury in newborn rats

INTRODUCTION

Preterm infants have risks of developing vitamin D deficiency. Thus we aimed to investigate the effect of vitamin D on hyperoxia-induced lung injury in newborn rats.

METHODS

Full term rat pups were included in the study 12-24 hr after delivery. The pups were randomly divided into eight groups as follows: normoxia control group (NC), normoxia plus vitamin D group (ND1, 1 ng/gr/day vitamin D), normoxia plus vitamin D group (ND2, 3 ng/gr/day vitamin D), normoxia plus vitamin D group (ND3, 5 ng/gr/day vitamin D), hyperoxia control group (HC), hyperoxia plus vitamin D group (HD1, 1 ng/gr/day vitamin D), hyperoxia plus Vitamin D group (HD2, 3 ng/gr/day vitamin D), hyperoxia plus vitamin D group (HD3, 5 ng/gr/day vitamin D). The histopathological effects of vitamin D were assessed by alveolar surface area (with mean linear intercept (MLI) method), apoptosis index and proliferating cell nuclear antigen (PCNA) index.

RESULTS

MLI values were significantly lower among three groups (HD1: 83.93 ± 1.95 μm, HD2: 81.76 ± 1.68 μm, and HD3: 82.33 ± 1.87 μm) when compared with HC group (92.98 ± 2.09 μm) (P = 0.001, P = 0.0004, P = 0.002, respectively). Apoptotic cell index were significantly lower among three treatment groups (HD1: 1.455 ± 0.153, HD2: 0.575 ± 0.079, and HD3: 0.700 ± 0.105) when compared with HC group (2.500 ± 0.263) (P = 0.001, P = 0.001, P = 0.001, respectively). Although PCNA positive cell index did not change in HD1 group (0.132 ± 0.008) (P > 0.05), there were significant increases in HD2 (0.277  ± 0.026) and HD3 (0.266 ± 0.018) group when compared with HC group (0.142 ± 0.010) (HD2 P = 0.001, HD3 P = 0.001).

CONCLUSION

Vitamin D seems to protect hyperoxia-induced lung injury in newborn rats. Pediatr Pulmonol. 2017;52:69-76. © 2016 Wiley Periodicals, Inc.

Emerging concepts in smooth muscle contributions to airway structure and function: implications for health and disease

Airway structure and function are key aspects of normal lung development, growth, and aging, as well as of lung responses to the environment and the pathophysiology of important diseases such as asthma, chronic obstructive pulmonary disease, and fibrosis. In this regard, the contributions of airway smooth muscle (ASM) are both functional, in the context of airway contractility and relaxation, as well as synthetic, involving production and modulation of extracellular components, modulation of the local immune environment, cellular contribution to airway structure, and, finally, interactions with other airway cell types such as epithelium, fibroblasts, and nerves. These ASM contributions are now found to be critical in airway hyperresponsiveness and remodeling that occur in lung diseases. This review emphasizes established and recent discoveries that underline the central role of ASM and sets the stage for future research toward understanding how ASM plays a central role by being both upstream and downstream in the many interactive processes that determine airway structure and function in health and disease.

Inhaled Vitamin D: A Novel Strategy to Enhance Neonatal Lung Maturation

INTRODUCTION

The physiologic vitamin D (VD), 1α,25(OH)₂D₃ (1,25D) is a local paracrine/autocrine effecter of fetal lung maturation. By stimulating alveolar type II cell and lipofibroblast proliferation and differentiation, parenterally administered 1,25D has been shown to enhance neonatal lung maturation; but due to the potential systemic side effects of the parenteral route, the translational value of these findings might be limited. To minimize the possibility of systemic toxicity, we examined the effects of VD on neonatal lung maturation, when delivered directly to lungs via nebulization.

METHODS

One-day-old rat pups were administered three different doses of 1,25D and its physiologic precursor 25(OH)D (25D), or the diluent, via nebulization daily for 14 days. Pups were sacrificed for lung, kidneys, and blood collection to determine markers of lung maturation, and serum 25D and calcium levels.

RESULTS

Compared to controls, nebulized 25D and 1,25D enhanced lung maturation as evidenced by the increased expression of markers of alveolar epithelial (SP-B, leptin receptor), mesenchymal (PPARγ, C/EBPα), and endothelial (VEGF, FLK-1) differentiation, surfactant phospholipid synthesis, and lung morphology without any significant increases in serum 25D and calcium levels.

CONCLUSIONS

Inhaled VD is a potentially safe and effective novel strategy to enhance neonatal lung maturation.

Vitamin D Depletion in Pregnancy Decreases Survival Time, Oxygen Saturation, Lung Weight and Body Weight in Preterm Rat Offspring

Animal studies suggest a role of vitamin D in fetal lung development although not studied in preterm animals. We tested the hypothesis that vitamin D depletion aggravates respiratory insufficiency in preterm rat offspring. Furthermore, the effects of vitamin D depletion on growth and lung surfactant were investigated. Female Sprague-Dawley rats were randomly assigned low vitamin D (VD_L) or control diet before mating and followed with serum 25-hydroxyvitamin D (s-25(OH)D) determinations. After cesarean section at gestational day 19 (E19) or day 22 (E22), placental weight, birth weight, crown-rump-length (CRL), oxygenation (SaO₂) at 30 min and survival time were recorded. The pup lungs were analyzed for phospholipid levels, surfactant protein A-D mRNA and the expression of the vitamin D receptor (VDR). S-25(OH)D was significantly lower in the VD_L group at cesarean section (12 vs. 30nmol/L, p<0.0001). Compared to the controls, E19 VD_L pups had lower birth weight (2.13 vs. 2.29g, p<0.001), lung weight (0.09 vs. 0.10g, p = 0.002), SaO₂(54% vs. 69%, p = 0.002) as well as reduced survival time (0.50 vs. 1.25h, p<0.0001). At E22, the VD_L-induced pulmonary differences were leveled out, but VD_L pups had lower CRL (4.0 vs. 4.5cm, p<0.0001). The phospholipid levels and the surfactant protein mRNA expression did not differ between the dietary groups. In conclusion, Vitamin D depletion led to lower oxygenation and reduced survival time in the preterm offspring, associated with reduced lung weight and birth weight. Further studies of vitamin D depletion in respiratory insufficiency in preterm neonates are warranted.

Biomarkers for Bronchopulmonary Dysplasia in the Preterm Infant

Bronchopulmonary dysplasia (BPD) is a chronic inflammatory lung disease of very-low-birth-weight (VLBW) preterm infants, associated with arrested lung development and a need for supplemental oxygen. Over the past few decades, the incidence of BPD has significantly raised as a result of improved survival of VLBW infants requiring mechanical ventilation. While early disease detection is critical to prevent chronic lung remodeling and complications later in life, BPD is often difficult to diagnose and prevent due to the lack of good biomarkers for identification of infants at risk, and overlapping symptoms with other diseases, such as pulmonary hypertension (PH). Due to the current lack of effective treatment available for BPD and PH, research is currently focused on primary prevention strategies, and identification of biomarkers for early diagnosis, that could also represent potential therapeutic targets. In addition, novel histopathological, biochemical, and molecular factors have been identified in the lung tissue and in biological fluids of BPD and PH patients that could associate with the disease phenotype. In this review, we provide an overview of biomarkers for pediatric BPD and PH that have been identified in clinical studies using various biological fluids. We also present a brief summary of the information available on current strategies and guidelines to prevent and diagnose BPD and PH, as well as their pathophysiology, risk factors, and experimental therapies currently available.

Impact of Nutrition on Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) remains a common morbidity of prematurity. Although the pathogenesis of BPD is recognized to be both multifactorial and complex, the role of nutrition in the pathophysiology of BPD is typically limited to management after a diagnosis has been made. Infants born small for gestational age and those who experience postnatal growth failure are more likely to have BPD. Therapies for lung disease, such as fluid restriction, diuretics, and corticosteroids, can negatively impact postnatal growth. Future research is needed to optimize nutritional strategies in the neonatal intensive care unit and following hospital discharge.

Intrauterine endotoxin-induced impairs pulmonary vascular function and right ventricular performance in infant rats and improvement with early vitamin D therapy

High pulmonary vascular resistance (PVR), proximal pulmonary artery (PA) impedance, and right ventricular (RV) afterload due to remodeling contribute to the pathogenesis and severity of pulmonary hypertension (PH). Intra-amniotic exposure to endotoxin (ETX) causes sustained PH and high mortality in rat pups at birth, which are associated with impaired vascular growth and RV hypertrophy in survivors. Treatment of ETX-exposed pups with antenatal vitamin D (vit D) improves survival and lung growth, but the effects of ETX exposure on RV-PA coupling in the neonatal lung are unknown. We hypothesized that intrauterine ETX impairs RV-PA coupling through sustained abnormalities of PA stiffening and RV performance that are attenuated with vit D therapy. Fetal rats were exposed to intra-amniotic injections of ETX, ETX+vit D, or saline at 20 days gestation (term = 22 days). At postnatal day 14, pups had pressure-volume measurements of the RV and isolated proximal PA, respectively. Lung homogenates were assayed for extracellular matrix (ECM) composition by Western blot. We found that ETX lungs contain decreased α-elastin, lysyl oxidase, collagen I, and collagen III proteins (P < 0.05) compared control and ETX+vit D lungs. ETX-exposed animals have increased RV mechanical stroke work (P < 0.05 vs. control and ETX+vit D) and elastic potential energy (P < 0.05 vs. control and ETX+vit D). Mechanical stiffness and ECM remodeling are increased in the PA (P < 0.05 vs. control and ETX+vit D). We conclude that intrauterine exposure of fetal rats to ETX during late gestation causes persistent impairment of RV-PA coupling throughout infancy that can be prevented with early vit D treatment.

Recent advances in the mechanisms of lung alveolarization and the pathogenesis of bronchopulmonary dysplasia

Alveolarization is the process by which the alveoli, the principal gas exchange units of the lung, are formed. Along with the maturation of the pulmonary vasculature, alveolarization is the objective of late lung development. The terminal airspaces that were formed during early lung development are divided by the process of secondary septation, progressively generating an increasing number of alveoli that are of smaller size, which substantially increases the surface area over which gas exchange can take place. Disturbances to alveolarization occur in bronchopulmonary dysplasia (BPD), which can be complicated by perturbations to the pulmonary vasculature that are associated with the development of pulmonary hypertension. Disturbances to lung development may also occur in persistent pulmonary hypertension of the newborn in term newborn infants, as well as in patients with congenital diaphragmatic hernia. These disturbances can lead to the formation of lungs with fewer and larger alveoli and a dysmorphic pulmonary vasculature. Consequently, affected lungs exhibit a reduced capacity for gas exchange, with important implications for morbidity and mortality in the immediate postnatal period and respiratory health consequences that may persist into adulthood. It is the objective of this Perspectives article to update the reader about recent developments in our understanding of the molecular mechanisms of alveolarization and the pathogenesis of BPD.

Association of vitamin D binding protein polymorphisms with bronchopulmonary dysplasia: a case-control study of gc globulin and bronchopulmonary dysplasia

OBJECTIVE

The pathophysiologies of bronchopulmonary dysplasia (BPD) are inflammation, infection, tissue damage, angiogenesis defects and genetic susceptibility. Because of the role of the vitamin D binding protein (Gc globulin) on these factors, we investigated the relationship between Gc globulin polymorphisms and BPD.

STUDY DESIGN

This case-control study was performed with 160 neonates (⩽32 gestational ages, ⩽1500 g). PCR DNA sequence analyses were used for GC gene rs4588 and rs7041 single-nucleotide polymorphisms.

RESULT

In the univariate analyses, it was observed that Gc2 was the only variant that was protective against BPD (Odd ratio (OR)=0.47, 95% coinfidence interval (CI)=0.24 to 0.89, P=0.020). In the multivariate analyses, Gc2 decreased the risk of disease (OR=0.15, 95% CI=0.029 to 0.79, P=0.026) independent of gestational age, birth weight, 5-min Appearance, Pulse, Grimace, Activity, and Respiration scores, respiratory distress syndrome and sepsis.

CONCLUSION

The Gc2 variant was, after adjusting for confounders, associated with a decrease in the frequency of BPD. Our study adds Gc globulin to the list of candidate genes that potentially contribute to the etiology of the disease.

Maternal high-fat diet is associated with impaired fetal lung development

Maternal nutrition has a profound long-term impact on infant health. Poor maternal nutrition influences placental development and fetal growth, resulting in low birth weight, which is strongly associated with the risk of developing chronic diseases, including heart disease, hypertension, asthma, and type 2 diabetes, later in life. Few studies have delineated the mechanisms by which maternal nutrition affects fetal lung development. Here, we report that maternal exposure to a diet high in fat (HFD) causes placental inflammation, resulting in placental insufficiency, fetal growth restriction (FGR), and inhibition of fetal lung development. Notably, pre- and postnatal exposure to maternal HFD also results in persistent alveolar simplification in the postnatal period. Our novel findings provide a strong association between maternal diet and fetal lung development.