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Filamentation by Escherichia coli subverts innate defenses during urinary tract infection

2006; National Academy of Sciences; Volume: 103; Issue: 52 Linguagem: Inglês

10.1073/pnas.0606329104

1091-6490

Sheryl S. Justice, David A. Hunstad, Patrick C. Seed, Scott J. Hultgren,

Gut microbiota and health

To establish disease, an infecting organism must overcome a vast array of host defenses. During cystitis, uropathogenic Escherichia coli (UPEC) subvert innate defenses by invading superficial umbrella cells and rapidly increasing in numbers to form intracellular bacterial communities (IBCs). In the late stages of the IBC pathway, filamentous and bacillary UPEC detach from the biofilm-like IBC, fluxing out of this safe haven to colonize the surrounding epithelium and initiate subsequent generations of IBCs, and eventually they establish a quiescent intracellular reservoir. Filamentous UPEC are not observed during acute infection in mice lacking functional Toll-like receptor 4 (TLR4), suggesting that the filamentous phenotype arises in response to host innate immunity. We investigated SulA, a cell division inhibitor associated with the SOS response, to gain insight into the role of filamentous UPEC in pathogenesis. A transcriptional reporter from P sulA revealed spatial and temporal differences in expression within IBCs, and it was active in the majority of filamentous UPEC. Although UTI89 and UTI89 Δ sulA both formed first-generation IBCs equally well, UTI89 Δ sulA was sharply attenuated in formation of second-generation IBCs and establishment of the quiescent intracellular reservoir. The virulence of UTI89 Δ sulA was restored in TLR4-deficient mice, suggesting that filamentation facilitates the transition to additional rounds of IBC formation by subverting innate immune responses. These findings demonstrate that transient SulA-mediated inhibition of cell division is essential for UPEC virulence in the murine model of cystitis.