Vitamin D and Immunity in Infants and Children

Abstract

The last couple of decades have seen an explosion in our interest and understanding of the role of vitamin D in the regulation of immunity. At the molecular level, the hormonal form of vitamin D signals through the nuclear vitamin D receptor (VDR), a ligand-regulated transcription factor. The VDR and vitamin D metabolic enzymes are expressed throughout the innate and adaptive arms of the immune system. The advent of genome-wide approaches to gene expression profiling have led to the identification of numerous VDR-regulated genes implicated in the regulation of innate and adaptive immunity. The molecular data infer that vitamin D signaling should boost innate immunity against pathogens of bacterial or viral origin. Vitamin D signaling also suppresses inflammatory immune responses that underlie autoimmunity and regulate allergic responses. These findings have been bolstered by clinical studies linking vitamin D deficiency to increased rates of infections, autoimmunity, and allergies. Our goals here are to provide an overview of the molecular basis for immune system regulation and to survey the clinical data from pediatric populations, using randomized placebo-controlled trials and meta-analyses where possible, linking vitamin D deficiency to increased rates of infections, autoimmune conditions, and allergies, and addressing the impact of supplementation on these conditions.

Vitamin D status and blood pressure in children and adolescents: a systematic review of observational studies

“…If the association proves to be causal, optimizing vitamin D status through supplementation in the pediatric population could slow the rising BP prevalence in this population group. In light of the widespread vitamin D deficiency, and the various health benefits of this vitamin on the musculoskeletal [ 137 ], immune [ 138 ], neurological [ 139 ], and cardiovascular [ 140 ] systems, optimizing vitamin D status in the pediatric population remain needed.…”

Malnutrition in Eosinophilic Gastrointestinal Disorders

“…Low serum vitamin D levels have been proposed to explain the increased prevalence of atopic and autoimmune diseases in Western countries [ 53 ]. Several efforts have focused on the role of vitamin D in the contribution of chronic dysregulated inflammation and its modulation [ 53 ].…”

“…Low serum vitamin D levels have been proposed to explain the increased prevalence of atopic and autoimmune diseases in Western countries [ 53 ]. Several efforts have focused on the role of vitamin D in the contribution of chronic dysregulated inflammation and its modulation [ 53 ]. Prevalence of EoE is higher in Western countries and cold climate zones, suggesting a possible association with low serum vitamin D levels [ 7 ].…”

“…Although there is emerging evidence of vitamin D in the development of the immune system and pathogenesis of allergic diseases, such as asthma, atopic dermatitis, and food allergy, no studies have evaluated its possible role in EGIDs development and remission [ 53 ]. Furthermore, based on the design of available studies (cross-sectional data analysis) no cause–effect relationship can be inferred.…”

Probing the Scope and Mechanisms of Calcitriol Actions Using Genetically Modified Mouse Models

“…(67) Thus, 1,25(OH) 2 D signaling increases expression of several types of proteins implicated in innate immune signaling, including PPRs, CD14/TLR4, as well as nucleotide-binding oligomerization domain protein 2 (NOD2), and also stimulates expression of genes encoding antimicrobial peptides including cathelicidin, which has antiviral activity against enveloped viruses in vitro and influenza A. (68) 1,25(OH) 2 D signaling through the VDR also increases the expression of several cytokines, including interleukin 1 (IL-1), a core component of innate immune responses; the neutrophil chemokine IL-8/CXCL8 is also induced, especially in macrophages infected with Mycobacterium tuberculosis. (69) Signaling by 1,25(OH) 2 D also regulates the innate-adaptive immune interface rendering dendritic cells less inflammatory.…”