Role of vitamin D in cystic fibrosis and non-cystic fibrosis bronchiectasis

Table 1 Potential immunological functions of vitamin D involved in the pathogenesis of lung disease

Function	Affected immune responses
Direct down-regulation of pro-inflammatory cytokines	IL-8, IL-6, and TNF-α
Direct up-regulation of regulatory cytokines	IL-10
Up-regulation of MKP-1	Inhibition of MAPKs pathways (critical for the mounting of innate immune responses)
Increase production and stabilization of IκB-α	Inhibition of NF-κB (regulates the expression of numerous inflammatory components)

MAPK: Mitogen-activated protein kinases; IL: Interleukin; TNF: Tumor necrosis factor; MKP-1: MAPK phosphatase-1; NF-κB: Nuclear-factor kappa B; IκB-α: Nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (the inhibitor of NF-κB).