Progressive lung destruction is the main cause of morbidity and mortality in cystic fibrosis (CF) due to persistent bacterial infection and inflammation along with a reduced capacity for epithelial repair. Levels of the anti-inflammatory mediator Lipoxin A4 (LXA4) have been reported to be reduced compared to inflammatory mediators in bronchoalveolar lavages of patients with CF. We previously shown that LXA4 targets airway epithelial cells and stimulates tight junction formation1. 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) human airway epithelia. Spontaneous epithelial repair (n=8, p<0.001) and cell migration (n=7, p<0.001) using a scratch assay and Boyden chamber assay was determined to be significantly slower in CF epithelial cultures (CuFi-1) compared to controls (NuLi-1). LXA4 triggered an increase in cell migration (n=6, p<0.001), proliferation (n=6, p<0.05) (MTT assay) and wound repair (n=6, p<0.005) in non-CF and cystic fibrosis airway epithelia. These responses to LXA4 were completely abolished by the FPR2 (LXA4receptor) antagonist, Boc2. The KATP channel opener, pinacidil, mimicked the LXA4 effect significantly increasing migration (n=6, p<0.001), proliferation (n=6, p<0.01) and epithelial repair (n=6, p<0.001) while the KATP channel inhibitor, glibenclamide, blocked the responses to LXA4. LXA4 did not affect potassium channel expression (n=4)(PCR) but significantly up regulated glibenclamide-sensitive (KATP) currents through the basolateral membrane (Ussing chamber) of NuLi-1 (n=4,p<0.01) and CuFi-1 (n=4,P<0.05) cells. The 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 (n=4, p<0.01) (Western Blot), while the effect of LXA4 on ERK phosphorylation was inhibited by glibenclamide. This work highlights LXA4 as potential therapeutic for exogenous delivery to restore levels in the lungs of CF patients, this in turn could help reduce the tissue destruction witnessed in the CF lung.
Epithelia and Smooth Muscle Interactions in Health and Disease (Dublin) (2013) Proc Physiol Soc 30, PC38
Poster Communications: Lipoxin stimulated epithelial repair is mediated through potassium currents
P. J. Buchanan1,2, P. McNally1, B. J. Harvey2, V. Urbach1,3
1. National Children's Research Cenre, Dublin, Ireland. 2. Royal college of Surgeon in Ireland, Dublin, Ireland. 3. Faculté de Médecine Paris Descartes - Site Necker, Paris, France.
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