Induction of Type I Interferon Signaling by Pseudomonas aeruginosa Is Diminished in Cystic Fibrosis Epithelial Cells

Abstract

The clinical manifestations of infection in cystic fibrosis (CF) are restricted to the lung, and involve a limited number of pathogens, suggesting a specific defect in mucosal immunity. We postulated that cystic fibrosis transmembrane conductance regulator (CTFR) mutations could affect the activation of type I interferon signaling in airway epithelial cells, which function in immune surveillance and initiate the recruitment and activation of immune cells. In response to infection with Pseudomonas aeruginosa, Ifnb was induced more than 100-fold in the murine lung, and the phosphorylation of STAT1 was similarly induced by the expected TLR4/TRIF/MD2/TBK1 cascade. The stimulation by P. aeruginosa of CF (IB3) cells and control (C-38) human cell lines similarly resulted in the induction of IFN-b, but to a significantly lower extent in CF airway cells. The potential consequences of diminished type I IFN signaling were demonstrated in a murine model of P. aeruginosa pneumonia, pretreatment with polyinosinic:polycytidylic acid significantly enhanced bacterial clearance and correlated with increased numbers of mature CD11c 1 / CD86 1 dendritic cells (DCs) in the lung. Using culture supernatants from CF or control cell lines stimulated with P. aeruginosa, we similarly demonstrated the diminished activation of human monocytederived DCs by incubation with CF compared with normal epithelial cell culture supernatants, which was dependent on IFN-b. These observations suggest that dysfunction of the CFTR in airway epithelial cells may contribute to impaired immune surveillance in the CF airway and resultant colonization by P. aeruginosa.

Activation of inflammasome signaling mediates pathology of acute P. aeruginosa pneumonia

“…Stimulation of type I IFN signaling with poly(I:C) in WT mice 24 hours prior to bacterial infection inhibited IL-1β and IL-18 secretion into the BAL (P = 0.0429 and P = 0.0018, respectively), improved PAK clearance from the airway, and reduced tissue damage, as assessed by TUNEL staining (Figure 4, E-H, and refs. [46][47][48]. The improved outcome could not be attributed to a reduction in either KC or TNF or to an increase in IL-1Ra (Figure 4, I-K).…”

“…6 independent, blinded reviewers assigned each image a lung injury score from 0 (healthy) to 5 (injured). Primary nasal epithelial cells were isolated and cultured as previously described (46)(47)(48)62). AMs, the primary cell type recovered from uninfected BAL (>85%), were resuspended in RPMI 1640 plus 10% fetal bovine serum.…”

“…Enumeration of neutrophil (MHCII -Ly6 + ), AM (CD11c + MHCII lo ), and DC (CD11c + MHCII + ) populations was performed as previously described (46). Antibody to CD4 (clone RM4.5; eBioscience) and IL-17A (clone eBio17B7; eBioscience) were used to identify CD4 (CD4 + CD11c -) and Th17 (IL-17 + CD4 + CD11c -) cell populations.…”

“…7-week-old C57BL/6 WT, Nlrc4 -/-, Il18r1 -/-, Il1r1 -/-, Cd4 -/-, or Ifnar -/-mice were intranasally inoculated with 50 μl P. aeruginosa (1 × 10 7 CFU, or 1 × 10 8 CFU for mortality), as previously described (29,46). WT, Cd4 -/-, and Ifnar -/-mice were bred in house, Il18r1 -/-and Il1r1 -/-mice were bought from Jackson Laboratories, and Nlrc4 -/-mice were provided by Genentech.…”

Low Sphingosine-1–Phosphate Impairs Lung Dendritic Cells in Cystic Fibrosis

“…Type 1 IFN signaling, recently shown to be activated in the CF lung (47), could also affect the activation and maturation of DCs. We found Type 1 IFN to be increased in CF BALF, but the supplementation of WT lavage with IFN-a/b at concentrations present in CF BALF did not affect the expression of the activation and maturation markers in lung DCs.…”