TLR4-mediated expulsion of bacteria from infected bladder epithelial cells.

Song, Jeongmin; Bishop, Brian L; Li, Guojie; Grady, Richard; Stapleton, Ann; Abraham, Soman N · Proc Natl Acad Sci U S A · 2009

basic_science · Level V

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Abstract

Uropathogenic Escherichia coli invade bladder epithelial cells (BECs) by direct entry into specialized cAMP regulated exocytic compartments. Remarkably, a significant number of these intracellular bacteria are subsequently expelled in a nonlytic and piecemeal fashion by infected BECs. Here, we report that expulsion of intracellular E. coli by infected BECs is initiated by the pattern recognition receptor, Toll-like receptor (TLR)4, after activation by LPS. Also, we reveal that caveolin-1, Rab27b, PKA, and MyRIP are components of the exocytic compartment, and that they form a complex involved in the exocytosis of bacteria. This capacity of TLR4 to mediate the expulsion of intracellular bacteria from infected cells represents a previously unrecognized function for this innate immune receptor.

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