Correlation of Gut Microbiota, Vitamin D Status, and Pulmonary Function Tests in Children With Cystic Fibrosis.

BACKGROUND

Children with cystic fibrosis (CF) are expected to have suboptimal serum vitamin D status and altered gut microbiota. The altered gut microbiota is hypothesized to have a pro-inflammatory effect that further complicates the existing respiratory inflammation. Emerging evidence suggests an association between vitamin D and gut microbiota. The aim of this study was to assess the relationships between 25-hydroxyvitamin D [25(OH)D] status, pulmonary function, and fecal bacteria in children with CF.

METHODS

In this cross-sectional study, a total of 35 children with CF (8.7 ± 2.83 years) and 24 controls without CF (9 ± 2.7 years) were included in this study. Serum 25(OH)D status was measured using the Elecsys vitamin D total II assay. In the CF group, gut microbiota composition was assessed using real-time PCR analysis. Pulmonary function tests (PFTs) were measured using spirometry. Comparisons between the CF and non-CF controls were conducted using the independent sample -test. In the CF group, one-way analysis of variance (ANOVA) was used to assess differences in PFTs and gut microbiota composition across the three vitamin D subgroups. The correlations between 25(OH)D status and PFTs, or gut microbiota composition, and PFTs with gut microbiota composition were analyzed using the Pearson's correlation coefficient test.

RESULTS

Children with CF had significantly lower serum 25(OH)D levels compared with children without CF (44.3 ± 22.4 vs. 59 ± 25.5, respectively, = 0.026). Children with CF with optimal serum 25(OH)D level had significantly higher levels of , and total bacteria ( = 0.007, = 0.007, and = 0.022, respectively). The level of was found to be significantly higher in mild forced expiratory volume in 1 s (FEV1) compared with moderate FEV1 ( = 0.032), whereas the level of the other bacteria species was comparable across FEV1 severity groups.

CONCLUSION

Our findings may encourage studies that target and modify gut microbiota to potentially achieve better outcomes in terms of respiratory function in CF.