Microbe–Mucus Interface in the Pathogenesis of Colorectal Cancer

Abstract

Overlying gastrointestinal epithelial cells is the transparent mucus layer that separates the lumen from the host. The dynamic mucus layer serves to lubricate the mucosal surface, to protect underlying epithelial cells, and as a transport medium between luminal contents and epithelial cells. Furthermore, it provides a habitat for commensal bacteria and signals to the underlying immune system. Mucins are highly glycosylated proteins, and their glycocode is tissue-specific and closely linked to the resident microbiota. Aberrant mucin expression and glycosylation are linked to chronic inflammation and gastrointestinal cancers, including colorectal cancer (CRC). Aberrant mucus production compromises the mucus layer and allows bacteria to come into close contact with the intestinal epithelium, potentially triggering unfavorable host responses and the subsequent development of tumors. Here, we review our current understanding of the interaction between the intestinal microbiota and mucus in healthy and CRC subjects. Deep knowledge of the intricate mechanisms of microbe–mucus interactions may contribute to the development of novel treatment strategies for CRC, in which a dysfunctional mucus layer is observed.

Mucosa-Associated Escherichia coli in Colorectal Cancer Patients and Control Subjects: Variations in the Prevalence and Attributing Features

“…In addition, recent studies have shown that bacterial biofilms are associated with human colon cancer [21,22].…”

“…In addition, recent studies have shown that bacterial biofilms are associated with human colon cancer [ 21 , 22 ]. Mucus-invasive bacterial biofilms, for example, were found on the colon mucosa of CRC patients more frequently than in healthy subjects [ 23 ].…”

An autologous colonic organoid‐derived monolayer model to study immune: bacterial interactions in Crohn's disease patients

“…Future experiments are essential to determine whether bacterial translocation in this model is the cause of immune cell activation. Finally, it is also possible that the result described here is an artefact of the monolayer model; bacterial contact with the apical membrane of the colonic epithelium is minimal in vivo due to the epithelium structure and secretion of both mucus and antimicrobial components, 22 or that effects observed from the co‐culture of F. prausnitzii are specific to that species of commensal bacteria.…”

Berberine as a Potential Agent for the Treatment of Colorectal Cancer

“…Akkermansia muciniphila ( A. muciniphila ) is a member of beneficial microbiota and a dedicated intestinal mucin degrader ( 171 ). Abnormal production and expression of mucin damage the mucinous layer, bringing bacteria into close contact with the intestinal epithelial cells and possibly triggering adverse host response and subsequent CRC development ( 172 ). BBR has been revealed to increase the growth of the populations of the symbiotic genus Akkermansia ( 173 ) and may further have effects on mucin expression.…”