RT Journal Article SR Electronic T1 Vitamin D deficiency alters airway structure and function in a chronic house dust mite exposure model JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP P1571 VO 42 IS Suppl 57 A1 Rachel Foong A1 Luke Berry A1 Prue Hart A1 Shelley Gorman A1 Graeme Zosky YR 2013 UL http://erj.ersjournals.com/content/42/Suppl_57/P1571.abstract AB Introduction Reduced levels of vitamin D are associated with airway hyperresponsiveness (AHR), airway remodelling and poor asthma control, however the causal link between these is yet to be established. We aimed to determine whether vitamin D deficiency would increase AHR and airway remodelling in a mouse model of chronic allergic asthma.Methods A physiologically relevant mouse model of vitamin D deficiency was developed by raising BALB/c mice on vitamin D-deficient or -replete diets. Offspring from -deficient and -replete mice of both sexes at 8 weeks of age were intranasally inoculated with house dust mite (HDM) extract (25 μg of protein in 50 μL of saline) or saline as a control 5 days a week for 5 weeks. AHR was assessed by measuring lung function responses to increasing doses of inhaled methacholine (MCh) 72 hours after the last HDM exposure. Lungs were fixed in formalin, embedded in paraffin and cut into 5 μm thick sections. Sections were stained with Masson’s Trichrome for airway smooth muscle (ASM) measurement.Results Both HDM and vitamin D deficiency on their own caused an increase in both ASM (p < 0.05) and AHR (p < 0.05). However, vitamin D deficiency reduced both ASM and baseline airway resistance when combined with HDM exposure such that these parameters were the equivalent to saline exposed vitamin D replete mice (p > 0.05).Conclusions Both vitamin D deficiency and HDM on their own increased ASM and airway resistance in mice but, paradoxically, when both were combined the responses were dampened.