Clostridium difficile toxin A stimulates intracellular calcium release and chemotactic response in human granulocytes.
Clostridium difficile, a common enteric pathogen, mediates tissue damage and intestinal fluid secretion by release of two protein exotoxins: toxin A, an enterotoxin, and toxin B, a cytotoxin. Because toxin A elicits an intense inflammatory reaction in vivo, we studied the effects of highly purified C. difficile toxins on activation of human granulocytes. Toxin A at concentrations of 10(-7) to 10(-6) M, but not toxin B, elicited a significant chemotactic and chemokinetic response by granulocytes that was comparable with that induced by the chemotactic factor N-FMLP (10(-7) M). Neither toxin stimulated release of superoxide anion from granulocytes. Toxin A produced a rapid, transient rise in cytosolic [Ca2+]i, as measured by quin 2 fluorescence. Pertussis toxin and depletion of intra- and extracellular calcium blocked the toxin A effect on cytosolic [Ca2+]i. These findings suggest that the inflammatory effects of C. difficile toxin A in the intestine may be related to its ability to mobilize intracellular Ca2+ and elicit a chemotactic response by granulocytes.
Pothoulakis
C
C
Section of Gastroenterology, Evans Memorial Department of Clinical Research, University Hospital, Boston, Massachusetts 02118.
Sullivan
R
R
Melnick
D A
DA
Triadafilopoulos
G
G
Gadenne
A S
AS
Meshulam
T
T
LaMont
J T
JT
D001427:Bacterial Toxins / Q000494:pharmacology*; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D002634:Chemotaxis, Leukocyte; D003013:Clostridium; D003600:Cytosol / Q000032:analysis; D004768:Enterotoxins / Q000494:pharmacology; D006098:Granulocytes / Q000032:analysis / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D006801:Humans; D013481:Superoxides / Q000378:metabolism
D001427:Bacterial Toxins; D004768:Enterotoxins; C041348:tcdA protein, Clostridium difficile; D013481:Superoxides; D002118:Calcium