Effect of Shiga toxin 2 on water and ion transport in human colon in vitro

Shiga toxin-producing Escherichia coli (STEC) colonize the lower segments o f the human gastrointestinal tract, causing gastrointestinal and systemic d iseases. In this study, the effects of Shiga toxin 2 (Stx2) on fluid absorp tion and ion transport in the human colon were examined. Net water movement (Jw) and short-circuit current (Isc) were simultaneously measured across t he colonic mucosa incubated with crude or purified Stx2. Stx2 significantly inhibited the absorptive J(w) with no effect on the basal I-sc after 60 mi n of exposure. These effects may be due to the inhibition of a nonelectroge nic transport system present in the surface colonic villus cells. Morpholog ical studies of the colonic mucosa treated with crude or purified Stx2 demo nstrated a selective damage in the absorptive villus epithelial cells. Thes e findings suggest that Stx2, inhibits water absorption across the human co lon by acting on a specific cell population: the mature, differentiated abs orptive villus epithelium.