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Proc Natl Acad Sci U S A. 2017 Oct 17;114(42):11027-11033. doi: 10.1073/pnas.1711395114. Epub 2017 Sep 25.

Resistin-like molecule β is a bactericidal protein that promotes spatial segregation of the microbiota and the colonic epithelium.

Author information

1
Department of Immunology, The University of Texas Southwestern Medical Center, Dallas, TX 75390.
2
Department of Dermatology, The University of Texas Southwestern Medical Center, Dallas, TX 75390.
3
Department of Immunology, The University of Texas Southwestern Medical Center, Dallas, TX 75390; lora.hooper@utsouthwestern.edu.
4
Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, TX 75390.

Abstract

The mammalian intestine is colonized by trillions of bacteria that perform essential metabolic functions for their hosts. The mutualistic nature of this relationship depends on maintaining spatial segregation between these bacteria and the intestinal epithelial surface. This segregation is achieved in part by the presence of a dense mucus layer at the epithelial surface and by the production of antimicrobial proteins that are secreted by epithelial cells into the mucus layer. Here, we show that resistin-like molecule β (RELMβ) is a bactericidal protein that limits contact between Gram-negative bacteria and the colonic epithelial surface. Mouse and human RELMβ selectively killed Gram-negative bacteria by forming size-selective pores that permeabilized bacterial membranes. In mice lacking RELMβ, Proteobacteria were present in the inner mucus layer and invaded mucosal tissues. Another RELM family member, human resistin, was also bactericidal, suggesting that bactericidal activity is a conserved function of the RELM family. Our findings thus identify the RELM family as a unique family of bactericidal proteins and show that RELMβ promotes host-bacterial mutualism by regulating the spatial segregation between the microbiota and the intestinal epithelium.

KEYWORDS:

antibacterial protein; innate immunity; intestinal epithelium; microbiota

PMID:
28973871
PMCID:
PMC5651776
DOI:
10.1073/pnas.1711395114
[Indexed for MEDLINE]
Free PMC Article

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