Mechanisms of chloride secretion induced by thermostable direct haemolysinof Vibrio parahaemolyticus in human colonic tissue and a human intestinal epithelial cell line
A. Takahashi et al., Mechanisms of chloride secretion induced by thermostable direct haemolysinof Vibrio parahaemolyticus in human colonic tissue and a human intestinal epithelial cell line, J MED MICRO, 49(9), 2000, pp. 801-810
Thermostable direct haemolysin (TDH) produced by Vibrio parahaemolyticus is
thought to play an important role in the severe diarrhoea caused by this o
rganism. This study investigated the enterotoxicity of TDH for human intest
inal cells. Addition of TDH to the mucosal side of human colonic tissue in
Ussing chambers caused increased short circuit currents (Isc), a process th
at was inhibited by 4,4 '-diisothiocyanatostilbene-2,2'-disulphonic acid (D
IDS), an inhibitor of Ca2+-activated chloride (Cl-) channels. With human co
lonic epithelial (Caco-2) cells, high Ise and intracellular Ca2+ concentrat
ions ([Ca2+](in)) were detected after the addition of TDH to the apical sid
e of the cell monolayer, The Ise decreased with the addition of DIDS, but n
ot with glybenclamide, 5-nitro-2-(3-phenylpropylamino) benzoic acid, or gad
olinium chloride, No Ise increase with TDH was observed when the Cl- in the
medium was replaced by gluconate or when Ca2+ was depleted, Similarly, TDH
did not raise [Ca2+](in) after depletion of extracellular Ca2+, R7, a muta
nt form of TDH, reduced the effects of TDH on Isc and [Ca2+](in) as did pro
tein kinase C (PKC) inhibitors. Thus, TDH increases Cl- secretion in human
colonic epithelial cells, apparently through mechanisms involving cell bind
ing and Ca2+ influx, followed by elevation of [Ca2+](in) associated with PK
C phosphorylation.