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Airway inflammation and infections
S83 Levels of Antimicrobial Peptides in the Airway of Children with Cystic fibrosis are not related to Serum Vitamin D Concentration
  1. RM Thursfield1,
  2. A Bush2,
  3. EWFW Alton1,
  4. JC Davies1
  1. 1National Heart and Lung Institute, Imperial College, London, UK
  2. 2Department of paediatric respiratory medicine, Royal Brompton Hospital, London, UK


Introduction There is convincing evidence of the clinical health benefits of adequate vitamin D in many respiratory diseases but the evidence in cystic fibrosis (CF) is unclear. There are increasing data on the role of vitamin D as an immunomodulatory agent and it is thought, from in-vitro data, that this may be via induction of the antimicrobial peptides, LL37 and HβD-2. We hypothesised that antimicrobial peptide levels would be increased in children with adequate vitamin D and this could account for reported improvements in lung function via improved airway defence.

Aims and methods The main aim was to establish if a relationship exists between vitamin D and antimicrobial peptides, LL37 and HβD-2, and whether any clinically beneficial effects of adequate vitamin D exist in children with CF. Bronchoalveolar fluid (BALF) supernatant levels of LL37 and HβD-2 were by measured by ELISA and serum 25(OH)D2 by mass spectrometry coupled with high-performance liquid chromatography.

Results Samples were collected from 120 children with CF (58% female); median age (range) 6.9 (0.1–17.6) years. One third of patients were vitamin D insufficient (<50 nmol/L). Median 25(OH)D2 was 57 nmol/L (range 7–191 nmol/L). LL37 ranged from 0.1–21.9 ng/mL with median value of 0.49 ng/mL and HβD-2 from <15.6 - >1000 pg/ml, median 150 pg/ml.

LL37 was significantly correlated with serum neutrophils (r= 0.4, P<0.0001), BALF total cell count (r=0.7, p<0.0001), and BALF neutrophil differential (r= 0.5, p<0.0001). These relationships were not seen with HβD-2. Contrary to our hypothesis neither LL37 nor HβD-2 correlated with vitamin D and no differences were seen between vitamin D ‘adequate’ and ‘insufficient’ patients. There was no association seen between vitamin D and FEV1 (r2=0.01, p=0.4).

Conclusions Our results demonstrate that there is not a relationship between serum 25(OH)D2 and BALF HβD-2 or LL37. If vitamin D is involved in the induction of such defence peptides in-vivo, the impact of this on protein levels may be limited in the degradative environment of the inflamed airway. In addition, we found no clinical or physiological effects of vitamin D deficiency. If any beneficial effect of vitamin D on respiratory health does exist in CF, it is small and not mediated via the antimicrobial pathway.

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