Listeriolysin O affects barrier function and induces chloride secretion in HT-29/B6 colon epithelial cells

Abstract

Listeria monocytogenes is a food-borne pathogen, which is able to induce diarrhea when residing in the intestine. We studied the effect of listeriolysin O (LLO), an extracellular virulence factor of L. monocytogenes, on intestinal transport and barrier function in monolayers of HT-29/B6 human colon cells using the Ussing technique to understand the pathomechanisms involved. Mucosal addition of LLO, but not a LLO mutant, induced a dose- and pH-dependent increase in short-circuit current ( ISC). Sodium and chloride tracer flux and DIDS sensitivity studies revealed that ISCwas mainly due to electrogenic chloride secretion. Barrier function was impaired by LLO, as assessed by transepithelial resistance ( Rt) and mannitol flux measurements. Intracellular signal transduction occurred through Ca2+release from intracellular stores and PKC activation. In conclusion, listeriolysin induces chloride secretion and perturbs epithelial barrier function, thus potentially contributing to Listeria-induced diarrhea.