Reduced expression of psoriasin in human airway cystic fibrosis epithelia

Psoriasin is a low molecular weight Ca²⁺-binding protein with known antimicrobial activity. Since human airway epithelial cells produce a number of powerful antimicrobial agents as part of their host defence, we investigated whether psoriasin was expressed in human bronchial epithelial cell lines. Expression was investigated in 16HBE14o- cells, derived from a normal individual, and compared to CFBE41o- cells, derived from a cystic fibrosis patient. We also examined psoriasin expression following treatment with factors pertinent to the CF lung-oxidant stress and exposure to pro-inflammatory cytokines. CFBE41o- cells demonstrated much reduced psoriasin levels compared to the 16HBE14o- cells. Increased psoriasin expression was seen following treatment with IL-22 and a cytomix of the pro-inflammatory cytokines IL-1β, TNF-α and IFN-γ; however, the oxidant stressor tert-butyl hydroperoxide had no apparent effect. Over-expression of human psoriasin into both cell lines resulted in increased internalization of Pseudomonas aeruginosa. In conclusion, expression of psoriasin - which has known anti-microbial activity in other systems - appears to be reduced in CFBE410- compared to 16HBE14o- cells, and its expression modified by exposure to pro-inflammatory cytokines.