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Commensal Bacteroidetes protect against Klebsiella pneumoniae colonization and transmission through IL-36 signalling

Sequeira, Richard P., McDonald, Julie A. K., Marchesi, Julian R. and Clarke, Thomas B. 2020. Commensal Bacteroidetes protect against Klebsiella pneumoniae colonization and transmission through IL-36 signalling. Nature Microbiology 5 (2) , pp. 304-313. 10.1038/s41564-019-0640-1

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The microbiota primes immune defences but the identity of specific commensal microorganisms that protect against infection is unclear. Conversely, how pathogens compete with the microbiota to establish their host niche is also poorly understood. In the present study, we investigate the antagonism between the microbiota and Klebsiella pneumoniae during colonization and transmission. We discover that maturation of the microbiota drives the development of distinct immune defence programmes in the upper airways and intestine to limit K. pneumoniae colonization within these niches. Immune protection in the intestine depends on the development of Bacteroidetes, interleukin (IL)-36 signalling and macrophages. This effect of Bacteroidetes requires the polysaccharide utilization locus of their conserved commensal colonization factor. Conversely, in the upper airways, Proteobacteria prime immunity through IL-17A, but K. pneumoniae overcomes these defences through encapsulation to effectively colonize this site. Ultimately, we find that host-to-host spread of K. pneumoniae occurs principally from its intestinal reservoir, and that commensal-colonization-factor-producing Bacteroidetes are sufficient to prevent transmission between hosts through IL-36. Thus, our study provides mechanistic insight into when, where and how commensal Bacteroidetes protect against K. pneumoniae colonization and contagion, providing insight into how these protective microorganisms could be harnessed to confer population-level protection against K. pneumoniae infection.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Biosciences
Publisher: Nature Research
ISSN: 2058-5276
Date of First Compliant Deposit: 3 February 2020
Date of Acceptance: 7 November 2019
Last Modified: 29 Nov 2020 12:05

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