Late-breaking abstract: Reducing inflammation in the lung by targeting the endothelial cystic fibrosis transmembrane conductance regulator with copper-tobramycin

Hyper-inflammation of the lungs is a key feature of cystic fibrosis and responsible for most patient mortality. The defect in CFTR is, on its own, proposed to be sufficient to cause inflammation in the absence of infection. Lung microvascular endothelial cells (HLMVEC) normally express CFTR and endothelial inflammation is reduced in vitro following treatment with the antibiotic and anti-oxidant copper-tobramycin (Gzuit et al . Br J Pharmacol, 168: 1165-81, 2012). Our aim was to determine whether the anti-inflammatory effects of copper-tobramycin are mediated through the CFTR chloride channel. HLMVECs were treated with the CFTR inhibitor GlyH-101 and copper-tobramycin (16 hours) and changes in IL-8 levels and CFTR expression measured by ELISA and immunocytochemistry (using the polyclonal antibody ‘Mr Pink'), respectively.CFTR protein was present at low levels in the cytoplasm of HLMVECs (n = 3). However, treatment with copper-tobramycin (100 µM), significantly increased CFTR levels (195 ± 17%, normalised to nuclear staining; n = 3; P < 0.01) with staining at the cell membrane. Inhibition of CFTR function with GlyH-101 (20 µM) increased IL-8 release under normal conditions (175 ± 10%; P < 0.01) and in the presence of an inflammatory stimulus (TNF-α: 10 ngml -1 ; 136 ± 3%; n = 4; P < 0.01). Co-treatment with copper-tobramycin (1 µM) significantly reduced IL-8 release to levels observed in untreated cells (P < 0.01; n = 6).The copper-tobramycin complex is believed to form spontaneously in vivo , and our data confirm its anti-inflammatory effects and indicate that they may be, in part, mediated through increased expression of CFTR.