Vitamin D and LL-37 in children with pneumonia

Background: Vitamin D is involved in the regulation of about1000 human genes. Recent studies suggest that vitamin D may have other actions outside of its classic functions related to bone and calcium homeostasis. The only human cathelicidin, LL 37, enhances microbial killing against a broad range of respiratory pathogens and has a defined vitamin D-dependent mechanism. Objective: evaluate the association between vitamin D status and plasma LL-37 levels in children with pneumonia. Study design: Forty consecutive children admitted to the chest unit of the Pediatric Department of Zagazig University Hospital with proven diagnosis of pneumonia were included in the study. They were 22 males and 18 females, of ages ranging from 2 to 5 years. In addition, 40 age and sex matched apparently healthy children served as a control group. A verbal consent was obtained from parent(s) of each child before inclusion to the study. All children were subjected to history taking, clinical examination, routine investigations (CBC, CRP and ESR) and chest X-ray done for patients only, as well as determination of serum 25-OH vitamin D and plasma LL-37. Results: The study revealed a highly significant increase of WBCs, ESR and CRP and a highly significant decrease in hemoglobin of patients. Absence of history of sun exposure, increased WBCs counts and low levels of vitamin D and LL-37 were considered as risk factors for pneumonia while site of residence, hemoglobin level and platelets count were not. Both vitamin D and LL-37 were significantly lower in patients than controls (P< 0.001). There were significant positive correlations between vitamin D and LL-37 in studied groups. Conclusion: Appropriate concentrations of vitamin D facilitate the ability of immune system to defend against respiratory tract infections through enhancing LL-37 production.