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F508CFTR on inflammatory response, ER stress, and Ca2+ of airway epitheliaDepartment of Molecular and Cell Biology, University of California-Berkeley, Berkeley, California
Submitted 11 June 2007 ; accepted in final form 3 September 2007
We tested whether cystic fibrosis (CF) airway epithelia have larger innate immune responses than non-CF or cystic fibrosis transmembrane conductance regulator (CFTR)-corrected cells, perhaps resulting from ER stress due to retention of
F508CFTR in the endoplasmic reticulum (ER) and activation of cytosolic Ca2+ (Cai) and nuclear factor (NF)-
B signaling. Adenovirus infections of a human CF (
F508/
F508) nasal cell line (CF15) provided isogenic comparisons of wild-type (wt) CFTR and
F508CFTR. In the absence of bacteria, there were no or only small differences among CF15, CF15-lacZ (
-galactosidase-expressing), CF15-wtCFTR (wtCFTR-corrected), and CF15-
F508CFTR (to test ER retention of
F508CFTR) cells in NF-
B activity, interleukin (IL)-8 secretion, Cai responses, and ER stress. Non-CF and CF primary cultures of human bronchial epithelial cells (HBE) secreted IL-8 equivalently. Upon infection with Pseudomonas aeruginosa (PA) or flagellin (key activator for airway epithelia), CF15, CF15-lacZ, CF15-wtCFTR, and CF15
F508CFTR cells exhibited equal PA binding, NF-
B activity, and IL-8 secretion; cells also responded similarly to flagellin when both CFTR (forskolin) and Cai signaling (ATP) were activated. CF and non-CF HBE responded similarly to flagellin + ATP. Thapsigargin (Tg, releases ER Ca2+) increased flagellin-stimulated NF-
B and ER stress similarly in all cells. We conclude that ER stress, Cai, and NF-
B signaling and IL-8 secretion were unaffected by wt- or
F508CFTR in control and during exposure to PA, flagellin, flagellin + ATP, or flagellin + ATP + forskolin. Tg, but not wt- or
F508CFTR, triggered ER stress. Previous measurements showing hyperinflammatory responses in CF airway epithelia may have resulted from cell-specific, rather than CFTR- or
F508CFTR-specific effects.
nuclear factor-
B; interleukin-8; adenovirus; inflammation; endoplasmic reticulum stress; ire1
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