Rapid modulation of electrolyte transport in Caco-2 cell monolayers by enteropathogenic Escherichia coli (EPEC) infection.

BACKGROUND AND AIMS The pathophysiology of enteropathogenic Escherichia coli (EPEC) diarrhoea remains uncertain. EPEC adhere to enterocytes and transduce signals which produce a characteristic "attaching and effacing" (A/E) lesion in the brush border membrane. The present in vitro study was designed to determine whether signal transduction by EPEC also influences electrolyte transport. METHODS Caco-2 cell monolayers were rapidly infected with wild type EPEC strain E2348/69, or the signal transduction-defective mutant 14.2.1(1), and mounted in Ussing chambers. RESULTS Strain E2348/69 stimulated a rapid but transient increase in short circuit current (Isc) which coincided with A/E lesion formation; this Isc response was absent on infection with strain 14.2.1(1). While the initial rise in Isc induced by E2348/69 was partially (approximately 35%) dependent on chloride, the remainder possibly represents an influx of sodium and amino acid(s) across the apical membrane. CONCLUSIONS The study directly shows that, after initial adhesion, EPEC induce major alterations in host cell electrolyte transport. The observed Isc responses indicate a rapid modulation of electrolyte transport in Caco-2 cells by EPEC, including stimulation of chloride secretion, for which signal transduction to host cells is a prerequisite.