Enterocytes / Intestinal Epithelial Cells (IECs) & Intestinal Mucosal Barrier / Mucus Layer

The defensive role developed by IECs relies largely on the variety of receptors they express at both extracellular (apical and basolateral) and intracellular compartments, and the capacity of Enterocytes / Intestinal Epithelial Cells (IECs) to communicate with immune and nervous systems
Pardo-Camacho et al. 2018

A small portion of the gut microbes is not physically separated from Enterocytes / Intestinal Epithelial Cells (IECs) by the Intestinal Mucosal Barrier / Mucus Layer and can physically interact with them.
Blumershine & Savage 1977 Microb. Ecol. 4: 95-103
Klaasen et al. 1992 FEMS Microbiol. Rev. 8: 165-180
Farkas et al. 2015 J. Immunol. Methods 421: 104-111

These include segmented filamentous bacteria (SFB, proposed name Candidatus savagella)
Ivanov & Littman 2010 Mucosal Immunol. 3: 209-212
Thompson et al. 2012 Environ. Microbiol. 14: 1454-1465

Enterocytes / Intestinal Epithelial Cells (IECs) form a single-layer physical barrier at the host-microbiota interface that is continuously replenished by multipotent intestinal stem cells residing in intestinal crypts
Peterson & Artis 2014 Nat. Rev. Immunol. 14: 141-153

The integrity of the barrier is further reinforced by inter-epithelial tight-junction proteins alongside the secretion of protective mucins
Peterson & Artis 2014 Nat. Rev. Immunol. 14: 141-153

see also:
Biological effects / Functions & Candidatus Savagella (Segmented filamentous bacteria/SFB)
Candidatus Savagella (Segmented filamentous bacteria/SFB) & Targets