PSEUDOMONAS-AERUGINOSA ENTRY INTO CACO-2 CELLS IS ENHANCED IN REPAIRING WOUNDED MONOLAYERS

Human respiratory cells participating in the repair of epithelial woun ds have been shown to be highly susceptible to Pseudomonas aeruginosa adherence. To ascertain whether such susceptibility is a common featur e of different repairing epithelial cells, Caco-2 cell monolayers were chemically injured, reincubated for 48 h to partially repair and expo sed to bacteria. Cells edging the wounds that spread and migrate to re -establish cell confluence were called 'repairing cells' while cells f ar from the wounds were called 'non-repairing cells'. By light microsc opy, bacteria were seen to adhere to and to enter into both repairing and non-repairing cells. The percentage of intracellular bacteria in r epairing cells was significantly higher than in non-repairing cells. T he higher susceptibility of repairing monolayers to bacterial entry wa s confirmed by the gentamicin exclusion assay. P. aeruginosa entry int o Caco-2 cells was greatly enhanced in non-injured confluent monolayer s treated with EDTA to disrupt intercellular junctions. As tight junct ion disfunctions have been described during the wound repair process, we speculate that exposure of basolateral receptors to bacterial ligan ds may account for the enhancement of P. aeruginosa internalization by repairing monolayers. (C) 1997 Academic Press Limited.