title: Alpha-hemolysin from Escherichia coli uses endogenous amplification through P2X receptor activation to induce hemolysis.
abstract: Escherichia coli is the dominant facultative bacterium in the normal intestinal flora. E. coli is, however, also responsible for the majority of serious extraintestinal infections. There are distinct serotypical differences between facultative and invasive E. coli strains. Invasive strains frequently produce virulence factors such as alpha-hemolysin (HlyA), which causes hemolysis by forming pores in the erythrocyte membrane. The present study reveals that this pore formation triggers purinergic receptor activation to mediate the full hemolytic action. Non-selective ATP-receptor (P2) antagonists (PPADS, suramin) and ATP scavengers (apyrase, hexokinase) concentration dependently inhibited HlyA-induced lysis of equine, murine, and human erythrocytes. The pattern of responsiveness to more selective P2-antagonists implies that both P2X(1) and P2X(7) receptors are involved in HlyA-induced hemolysis in all three species. In addition, our results also propose a role for the pore protein pannexin1 in HlyA-induced hemolysis, as non-selective inhibitors of this channel significantly reduced hemolysis in the three species. In conclusion, activation of P2X receptors and possibly also pannexins augment hemolysis induced by the bacterial toxin, HlyA. These findings potentially have clinical perspectives as P2 antagonists may ameliorate symptoms during sepsis with hemolytic bacteria.
authors.affiliation: Department of Physiology and Biophysics, Water and Salt Research Center, Aarhus University, Ole Worms Alle 1160, 8000 Aarhus C, Denmark.
authors.forename: Marianne
authors.initials: M
authors.lastname: Skals
authors.forename: Niklas R
authors.initials: NR
authors.lastname: Jorgensen
authors.forename: Jens
authors.initials: J
authors.lastname: Leipziger
authors.forename: Helle A
authors.initials: HA
authors.lastname: Praetorius
mesh_terms: D000251:Adenosine Triphosphatases / Q000494:pharmacology; D000818:Animals; D017630:Connexins / Q000037:antagonists & inhibitors; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development*; D029968:Escherichia coli Proteins / Q000494:pharmacology*; D006460:Hemolysin Proteins / Q000494:pharmacology*; D006461:Hemolysis / Q000187:drug effects*; D006736:Horses; D006801:Humans; D051379:Mice; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058469:Receptors, Purinergic P2X
chemical_list: D017630:Connexins; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D000251:Adenosine Triphosphatases; C027201:ectoATPase