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Vitamin D supplementation of initially vitamin D-deficient mice diminishes lung inflammation with limited effects on pulmonary epithelial integrity.

ABSTRACT: In disease settings, vitamin D may be important for maintaining optimal lung epithelial integrity and suppressing inflammation, but less is known of its effects prior to disease onset. Female BALB/c dams were fed a vitamin D3-supplemented (2280 IU/kg, VitD+) or nonsupplemented (0 IU/kg, VitD-) diet from 3 weeks of age, and mated at 8 weeks of age. Male offspring were fed the same diet as their mother. Some offspring initially fed the VitD- diet were switched to a VitD+ diet from 8 weeks of age (VitD-/+). At 12 weeks of age, signs of low-level inflammation were observed in the bronchoalveolar lavage fluid (BALF) of VitD- mice (more macrophages and neutrophils), which were suppressed by subsequent supplementation with vitamin D3 There was no difference in the level of expression of the tight junction proteins occludin or claudin-1 in lung epithelial cells of VitD+ mice compared to VitD- mice; however, claudin-1 levels were reduced when initially vitamin D-deficient mice were fed the vitamin D3-containing diet (VitD-/+). Reduced total IgM levels were detected in BALF and serum of VitD-/+ mice compared to VitD+ mice. Lung mRNA levels of the vitamin D receptor (VDR) were greatest in VitD-/+ mice. Total IgG levels in BALF were greater in mice fed the vitamin D3-containing diet, which may be explained by increased activation of B cells in airway-draining lymph nodes. These findings suggest that supplementation of initially vitamin D-deficient mice with vitamin D3 suppresses signs of lung inflammation but has limited effects on the epithelial integrity of the lungs.

SUBMITTER: Gorman S

PROVIDER: S-EPMC5555896 | biostudies-other | 2017 Aug

REPOSITORIES: biostudies-other

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Project description:Background: In addition to its canonical functions, vitamin D has been proposed to be an important mediator of the immune system. Despite ample sunshine, vitamin D deficiency is prevalent (> 80%) in the Middle East, resulting in a high rate of supplementation. However, the underlying molecular mechanisms of the specific regimen and potential factors affecting an individual’s response to vitamin D are not well characterized. Objective: To characterize changes in blood transcriptomic and the potential mechanisms associated with vitamin D3 supplementation and response. Design: In this intervention study, one hundred vitamin D-deficient women were given a weekly oral dose (50,000 IU) of vitamin D3 for three months. A high-throughput targeted PCR, composed of 264 genes representing important blood transcriptomic fingerprints in health and disease states, was performed on pre- and post-supplementation blood samples to profile the molecular response to vitamin D3. Multivariate, network, gene ontology, and literature mining analyses were used for the interpretation of the transcriptomic profiling results. Results: We identified 54 differentially expressed genes that were strongly modulated by vitamin D3 supplementation. Network analyses showed significant changes in the immune-related pathways such as TLR4/CD14 and IFN receptors, and catabolic processes related to NFkB, which were subsequently confirmed by gene ontology enrichment analyses. We proposed a model for vitamin D3 response, using the reduced expression of the molecules involved and the receptor-mediated intra-cellular signaling leading to reduce cytokine production. Conclusions: Blood-transcriptomic profiles of vitamin D3 response were generated using a targeted blood gene panel. Vitamin D has a strong effect on the immune system, G-coupled protein receptor signaling, and the ubiquitin system. We highlighted the major molecular changes and biological processes induced by vitamin D3, which will help to further investigate the effectiveness of vitamin D supplementation among individuals in the Middle East.

Project description:INTRODUCTION:Our previous study-level (aggregate data) meta-analysis suggested that vitamin D supplements may be beneficial for bone density specifically in children with vitamin D deficiency. However, the misclassification of vitamin D status inherent in study-level data means that the results are not definitive and cannot provide an accurate assessment of the size of any effect. Therefore, we propose to undertake an individual patient data (IPD) meta-analysis to determine whether the effect of vitamin D supplementation on bone density in children differs according to baseline vitamin D status, and to specifically estimate the effect of vitamin D in children who are vitamin D deficient. METHODS AND ANALYSIS:This study has been designed to adhere to the Preferred Reporting Items for Systematic Review and Meta-Analyses of IPD statement. We will include randomised placebo-controlled trials of vitamin D supplementation reporting bone density outcomes at least 6 months after the study commenced in children and adolescents (aged <20 years) without coexistent medical conditions or treatments causing osteoporosis. We will update the search of the original review to cover the period 2009-2017, using the same methods as the original review. Fully anonymised data on all randomised patients will be requested. Outcomes will be femoral neck, total hip, lumbar spine and proximal and distal forearm bone mineral density, and total body bone mineral content. A two-stage IPD meta-analysis will be used to examine the effect of baseline serum 25-hydroxyvitamin D (25(OH)D) on treatment effect for each bone density outcome. Restricted maximum likelihood will be used to estimate the random-effects meta-analysis models, with 95% CI for summary effects. Heterogeneity will be assessed by I2 and potential publication bias (small-study effects) and availability bias by funnel plots, Egger's test and Peter's test. ETHICS AND DISSEMINATION:Ethics approval will not be required as the data are to be used for the primary purpose for which they were collected and all original individual studies had ethics approval. Results of the IPD meta-analysis will be submitted for publication in a peer-reviewed journal. PROSPERO REGISTRATION NUMBER:CRD42017068772.

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Vitamin D supplementation of initially vitamin D-deficient mice diminishes lung inflammation with limited effects on pulmonary epithelial integrity.

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