RESUMO
Vitamin D supplementation at the current UK recommended level (400â IU·day-1) or enhanced supplementation (1000â IU·day-1) failed to achieve adequate levels of vitamin D (>75â nmol·L-1) in vitamin-D-insufficient children with acute wheeze https://bit.ly/3J43Ouo.
RESUMO
Rationale: Vitamin D deficiency is common in patients with asthma and chronic obstructive pulmonary disease (COPD). Low 25-hydroxyvitamin D (25[OH]D) levels may represent a cause or a consequence of these conditions.Objectives: To determine whether vitamin D metabolism is altered in asthma or COPD.Methods: We conducted a longitudinal study in 186 adults to determine whether the 25(OH)D response to six oral doses of 3 mg vitamin D3, administered over 1 year, differed between those with asthma or COPD versus control subjects. Serum concentrations of vitamin D3, 25(OH)D3, and 1α,25-dihydroxyvitamin D3 (1α,25[OH]2D3) were determined presupplementation and postsupplementation in 93 adults with asthma, COPD, or neither condition, and metabolite-to-parent compound molar ratios were compared between groups to estimate hydroxylase activity. Additionally, we analyzed 14 datasets to compare expression of 1α,25(OH)2D3-inducible gene expression signatures in clinical samples taken from adults with asthma or COPD versus control subjects.Measurements and Main Results: The mean postsupplementation 25(OH)D increase in participants with asthma (20.9 nmol/L) and COPD (21.5 nmol/L) was lower than in control subjects (39.8 nmol/L; P = 0.001). Compared with control subjects, patients with asthma and COPD had lower molar ratios of 25(OH)D3-to-vitamin D3 and higher molar ratios of 1α,25(OH)2D3-to-25(OH)D3 both presupplementation and postsupplementation (P ≤ 0.005). Intergroup differences in 1α,25(OH)2D3-inducible gene expression signatures were modest and variable if statistically significant.Conclusions: Attenuation of the 25(OH)D response to vitamin D supplementation in asthma and COPD associated with reduced molar ratios of 25(OH)D3-to-vitamin D3 and increased molar ratios of 1α,25(OH)2D3-to-25(OH)D3 in serum, suggesting that vitamin D metabolism is dysregulated in these conditions.
Assuntos
Asma/metabolismo , Calcifediol/metabolismo , Calcitriol/metabolismo , Colecalciferol/metabolismo , Doença Pulmonar Obstrutiva Crônica/metabolismo , Vitaminas/metabolismo , 25-Hidroxivitamina D3 1-alfa-Hidroxilase/genética , Estudos de Casos e Controles , Colecalciferol/farmacocinética , Colestanotriol 26-Mono-Oxigenase/genética , Citocromo P-450 CYP3A/genética , Família 2 do Citocromo P450/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/genética , Polimorfismo de Nucleotídeo Único , Ensaios Clínicos Controlados Aleatórios como Assunto , Proteína de Ligação a Vitamina D/genética , Vitamina D3 24-Hidroxilase/genética , Vitaminas/farmacocinéticaRESUMO
INTRODUCTION: Vitamin D is best known for its role in bone health; however, the discovery of the vitamin D receptor and the expression of the gene encoding the vitamin D 1α-hydroxylase (CYP27B1) enzyme in a wide variety of tissues including immune cells and respiratory epithelium has led to the discovery of potential roles for vitamin D in the prevention of acute wheeze. METHODS: We review here the literature concerning the relationships between circulating 25-hydroxyvitamin D (25(OH)D) concentration and secondary prevention of acute wheeze attacks in preschool and school-age children. RESULTS: Epidemiological data suggest that vitamin D insufficiency (25(OH)D <75 nmol/L) is highly prevalent in preschool and school-age children with wheeze. Preschool age children with a history of wheeze attacks and circulating 25(OH)D <75 nmol/L are at increased risk and frequency of future acute wheeze. However, no consistent association between low vitamin D status and risk of acute wheeze is reported in school-age children. Seven randomised controlled trials (RCTs) with relatively small sample sizes (30-430) and variable quality showed inconsistent results regarding the effect of oral vitamin D supplementation during childhood on the risk of asthma attacks, asthma symptom control, inhaled corticosteroid requirements, spirometry and unscheduled healthcare attendances for wheeze. A RCT showed that vitamin D supplementation had no effect on the frequency of unplanned healthcare attendances due to acute wheeze in 22 preschool children. DISCUSSION: An evidence-based recommendation for the use of vitamin D as a preventive therapy for wheeze attacks cannot be made until results of further trials are available. The assessment of circulating 25(OH)D concentration and the optimisation of vitamin D status to prevent acute respiratory tract infections, and to maintain skeletal and general health in preschool and school-age children with acute wheeze is worthwhile in its own right, but whether this will reduce the risk of acute wheeze attacks is unclear.