Cell Host & Microbe
Volume 12, Issue 2, 16 August 2012, Pages 139-152
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Article
Transient Inability to Manage Proteobacteria Promotes Chronic Gut Inflammation in TLR5-Deficient Mice

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Summary

Colitis results from breakdown of homeostasis between intestinal microbiota and the mucosal immune system, with both environmental and genetic influencing factors. Flagellin receptor TLR5-deficient mice (T5KO) display elevated intestinal proinflammatory gene expression and colitis with incomplete penetrance, providing a genetically sensitized system to study the contribution of microbiota to driving colitis. Both colitic and noncolitic T5KO exhibited transiently unstable microbiotas, with lasting differences in colitic T5KO, while their noncolitic siblings stabilized their microbiotas to resemble wild-type mice. Transient high levels of proteobacteria, especially enterobacteria species including E. coli, observed in close proximity to the gut epithelium were a striking feature of colitic microbiota. A Crohn’s disease-associated E. coli strain induced chronic colitis in T5KO, which persisted well after the exogenously introduced bacterial species had been eliminated. Thus, an innate immune deficiency can result in unstable gut microbiota associated with low-grade inflammation, and harboring proteobacteria can drive and/or instigate chronic colitis.

Highlights

► TLR5-deficient mice (T5KO) are prone to develop postweaning gut inflammation ► Colitic T5KO are associated with increased microbial volatility and proteobacteria ► T5KO show increased susceptibility to Crohn’s disease-associated E. coli (AIEC) ► AIEC persists longer in T5KO and induces chronic intestinal inflammation

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