Enterotoxic effect of the vacuolating toxin produced by Helicobacter pylori in Caco-2 cells.
Preliminary clinical evidence suggests that Helicobacter pylori may be associated with diarrhea through its vacuolating toxin (VacA). To establish whether VacA induces intestinal secretion, epithelial damage, or both, purified pH-activated VacA was added to Caco-2 cell monolayers mounted in Ussing chambers, and electrical parameters were monitored. Mucosal addition of VacA induced an increase in short circuit current, consistent with enterotoxic effect. The effect was time- and dose-dependent and saturable. It was not found if the toxin was not pH-activated, added to the serosal side, or preheated. In cells preloaded with the Ca2+ buffering compound BAPTA/AM or with the Cl- channel inhibitor 5-nitro-2-3-(3-phenylpropylamino)benzoic acid, short circuit current did not change, indicating that VacA induces activation of Ca2+-dependent Cl- channels. VacA did not show cytopathic effects, as judged by tissue resistance. These results support the hypothesis that H. pylori may be associated with diarrhea through production of VacA.
Guarino
A
A
Department of Pediatrics, University Federico II, Naples, Italy. alfguari@cds.unina.it
Bisceglia
M
M
Canani
R B
RB
Boccia
M C
MC
Mallardo
G
G
Bruzzese
E
E
Massari
P
P
Rappuoli
R
R
Telford
J
J
D001426:Bacterial Proteins / Q000008:administration & dosage / Q000096:biosynthesis / Q000633:toxicity*; D001427:Bacterial Toxins / Q000008:administration & dosage / Q000096:biosynthesis / Q000633:toxicity*; D001692:Biological Transport / Q000187:drug effects; D018938:Caco-2 Cells / Q000187:drug effects; D003603:Cytotoxins / Q000008:administration & dosage / Q000096:biosynthesis / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D017097:Electric Impedance; D016480:Helicobacter pylori / Q000378:metabolism*; D006801:Humans; D007202:Indicators and Reagents / Q000494:pharmacology; D007422:Intestines / Q000187:drug effects*; D014617:Vacuoles / Q000187:drug effects
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003603:Cytotoxins; D007202:Indicators and Reagents; C074689:VacA protein, Helicobacter pylori; D004533:Egtazic Acid; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid