Role of Vitamin D Levels in Adaptive and Innate Immune Function and Clinical Allergic Disease in Infancy and Early Childhood
A study published in the journal Clinical & Experimental Allergy investigated the association of vitamin D status at birth and at six months of age with innate immune function and clinical allergic disease in infancy and early childhood.
The study included a subset of 225 infants who were previously enrolled in a randomised controlled trial that investigated the effects of fish oil supplementation (650 mg) on allergic outcomes in infancy. Cord blood (CB) samples from the umbilical artery or vein at delivery and peripheral blood from this subset of six-month-old infants were obtained. Cytokine levels and innate and adaptive immune functions at six months of age were assessed in response to house dust mite (HDM), ovalbumin (OVA), betalactoglobulin (BLG) or toll-like receptor (TLR) ligands including polyinosinic:polycytidylic acid (TLR3), lipoteichoic acid (TLR2), CpG oligonucleotide (TLR9) and lipopolysaccharide (TLR4). In addition, clinical outcomes such as eczema, wheeze and allergen sensitisation were assessed up to 30 months of age.
Higher vitamin D levels in infants at birth resulted in lower levels of T helper (Th) 2 cytokines to food (OVA) and inhalant (HDM) allergens by six months of age. Furthermore, infants with CB vitamin D level <50 nmol/L by six months of age had significantly higher production of IL-5 and IL-13 in response to HDM as well as IL-5 in response to OVA compared to those with vitamin D levels >75 nmol/L. Higher vitamin D levels at birth were linked with lower inflammatory Th1 cytokines IFNγ and TNFα in response to HDM at six months of age. Infants with higher vitamin D levels at birth showed greater response to TLR ligands and were associated with a low risk of eczema at six and 12 months of age.
This study demonstrates the association between vitamin D status and immune function and symptomatic allergic disease in high-risk infants. Lower CB vitamin D levels at birth is linked with the development of an immune profile associated with an emerging allergic phenotype and greater eczema risk during childhood.
News source: Jones AP, D'Vaz N, Meldrum S, et al. 25-hydroxyvitamin D3 status is associated with developing adaptive and innate immune responses in the first 6 months of life. Clin Exp Allergy. 2015;45(1):220–231.