Brush border intermicrovillar adhesion limits bacteria attachment to the small intestine brush border

Area of Science:

• Cell Biology
• Microbiology
• Immunology

Background:

• The intestinal brush border, formed by microvilli, is crucial for nutrient absorption and barrier function.
• The intermicrovillar adhesion complex (IMAC) maintains brush border integrity, and its disruption is linked to intestinal diseases.
• Segmented filamentous bacteria (SFB) are known gut commensals with complex interactions with the host epithelium.

Purpose of the Study:

• To investigate the role of the brush border and IMAC in host-microbe interactions.
• To understand how SFB interact with and modify the host intestinal epithelium.
• To identify the brush border's function in host defense against gut bacteria.

Main Methods:

• Utilized IMAC-deficient mice to study brush border structure and bacterial colonization.
• Employed microscopy and molecular biology techniques to analyze bacterial attachment and host cell responses.
• Investigated the recruitment of specific proteins (EPS8, IRTKS, Arp2/3, ZO-1) at the SFB-host interface.

Main Results:

• IMAC-deficient mice exhibited dysbiosis with increased adherent and mucosal bacteria in the terminal ileum.
• SFB were found to recruit microvilli-associated proteins and remodel host actin.
• SFB integrated host protein ZO-1 into their attachment structures, indicating a mature host-microbe interface.

Conclusions:

• The brush border plays a critical role in host defense against luminal microbes.
• SFB actively remodel the host intestinal epithelium, utilizing brush border components.
• The SFB-host interface demonstrates a complex maturation process mirroring the bacterial lifecycle.