Influence of adhesins on the interaction of Escherichia coli with human phagocytes

Abstract

The fitness between bacterial adhesions and target cell receptors, determining bacterial adherence to epithelial cells in urinary tract infections, was shown to influence also the interaction with human polymorphonuclear leukocytes (PMNL). Two sets of homogenic strains, constructed to express either, both, or none of the globotetraosylceramide-sensitive (GS) adhesins specific for globoseries glycolipid receptors or the mannose-sensitive (MS) adhesins inhibited by α-methyl mannoside were compared regarding charge, hydrophobicity, and binding to PMNL. The mutants of a hydrophilic pyelonephritis strain required MS adhesins for binding to and activation of the PMNL. Removal of the MS adhesins from the mutant carrying both MS and GS adhesins abolished chemiluminescence and binding. A pronounced chemiluminescence reaction was induced by the hydrophobic strain without GS or MS adhesins. Transformants of this strain expressing the MS adhesin bound to and activated the PMNL. Poor binding and activation were found with mutants and transformants carying only the GS adhesins. The improved reactivity after coating of the PMNL with the appropriate receptor glycolipid supported the previously reported absence of globoseries glycolipids in those cells as the reason for the refractoriness to bacteria with GS adhesins. The mechanism of binding, which improves epithelial cell adhesion, may prevent binding to PMNL, thus improving the survival of Escherichia coli in the kidney.