ASIALO GM1 IS A RECEPTOR FOR PSEUDOMONAS-AERUGINOSA ADHERENCE TO REGENERATING RESPIRATORY EPITHELIAL-CELLS

We investigated the implication of asialo GM1 as an epithelial recepto r in the increased Pseudomonas aeruginosa affinity for regenerating re spiratory epithelial cells from cystic fibrosis (CF) and non-CF patien ts. Human respiratory epithelial cells were obtained from nasal polyps of non-CF subjects and of CF patients homozygous for the Delta F 508 transmembrane conductance regulator protein (CFTR) mutation and cultur ed according to the explant-outgrowth model. At the periphery of the o utgrowth, regenerating respiratory epithelial cells spreading over the collagen I matrix with lamellipodia were observed, characteristic of respiratory epithelial wound repair after injury. P. aeruginosa adhere nce to regenerating respiratory epithelial cells was found to be signi ficantly greater in the Delta F 508 homozygous CF group than in the no n-CF group (P < 0.001). In vitro competitive binding inhibition assays performed with rabbit polyclonal antibody against asialo GM1 demonstr ated that blocking asialo GM1 reduces P. aeruginosa adherence to regen erating respiratory epithelial cells in Delta F 508 homozygous CF cult ures (P < 0.001) as well as in non-CF cultures (P < 0.001). Blocking o f asialo GM1 was significantly more efficient in CF patients than in n on-CF subjects (P < 0.05). Distribution of asialo GM1 as determined by preembedding labelling and immunoelectron microscopy clearly demonstr ated the specific apical membrane expression of asialo GM1 by regenera ting respiratory epithelial cells, whereas other cell phenotypes did n ot apically express asialo GM1. These results demonstrate that (i) asi alo GM1 is an apical membrane receptor for P. aeruginosa expressed at the surface of CF and non-CF regenerating respiratory epithelial cells and (ii) asialo GM1 is specifically recovered in regenerating respira tory epithelium. These results suggest that in CF, epithelial repair r epresents the major event which exposes asialo GM1 for P. aeruginosa a dherence.