Lipoxin A4-mediated KATP potassium channel activation results in cystic fibrosis airway epithelial repair

Abstract

The main cause of morbidity and mortality in cystic fibrosis (CF) is progressive lung destruction as a result of persistent bacterial infection and inflammation, coupled with reduced capacity for epithelial repair. Levels of the anti-inflammatory mediator lipoxin A4 (LXA4) have been reported to be reduced in bronchoalveolar lavages of patients with CF. We investigated the ability of LXA4 to trigger epithelial repair through the initiation of proliferation and migration in non-CF (NuLi-1) and CF (CuFi-1) airway epithelia. Spontaneous repair and cell migration were significantly slower in CF epithelial cultures (CuFi-1) compared with controls (NuLi-1). LXA4 triggered an increase in migration, proliferation, and wound repair of non-CF and CF airway epithelia. These responses to LXA4 were completely abolished by the ALX/FPR2 receptor antagonist, Boc2 and ALX/FPR2 siRNA. The KATP channel opener pinacidil mimicked the LXA4 effect on migration, proliferation, and epithelial repair, whereas the KATP channel inhibitor, glibenclamide, blocked the responses to LXA4. LXA4 did not affect potassium channel expression but significantly upregulated glibenclamide-sensitive (KATP) currents through the basolateral membrane of NuLi-1 and CuFi-1 cells. MAP kinase (ERK1/2) inhibitor, PD98059 , also inhibited the LXA4-induced proliferation of NuLi-1 and CuFi-1 cells. Finally, both LXA4 and pinacidil stimulated ERK-MAP kinase phosphorylation, whereas the effect of LXA4 on ERK phosphorylation was inhibited by glibenclamide. Taken together, our results provided evidence for a role of LXA4 in triggering epithelial repair through stimulation of the ALX/FPR2 receptor, KATP potassium channel activation, and ERK phosphorylation. This work suggests exogenous delivery of LXA4, restoring levels in patients with CF, perhaps as a potential therapeutic strategy.