We read with great interest the article by Flemer et al , which suggests that analysis of the oral microbiota could potentially be used as a screening method for colorectal cancer (CRC) and polyp detection.1  Fusobacterium  ( F .) nucleatum is one of the most densely colonised bacterial species in the oral cavity and is known to be associated with periodontitis.2 Recently, many researchers have demonstrated that F . nucleatum is related to CRC development and pathogenicity.3 4 However, the relationship between F . nucleatum in CRC and the oral cavity is not well understood. For this purpose, we examined whether identical strains of F . nucleatum could be isolated from CRC and saliva specimens obtained from the same patient. The approach used in this study is detailed in figure 1A (see online supplementary information for details). We collected CRC and saliva samples from 14 patients (online supplementary table 1) and isolated bacteria from the specimens on Fusobacterium -selective agar. All colonies (1,351 in total) were analysed by PCR using …

https://gut.bmj.com/content/gutjnl/68/7/1335.full.pdf

Patients with colorectal cancer have identical strains of Fusobacterium nucleatum in their colorectal cancer and oral cavity.

The oralome is the summary of the dynamic interactions orchestrated between the ecological community of oral microorganisms (comprised of up to approximately 1000 species of bacteria, fungi, viruses, archaea and protozoa - the oral microbiome) that live in the oral cavity and the host. These microorganisms form a complex ecosystem that thrive in the dynamic oral environment in a symbiotic relationship with the human host. However, the microbial composition is significantly affected by interspecies and host-microbial interactions, which in turn, can impact the health and disease status of the host. In this review, we discuss the composition of the oralome and inter-species and host-microbial interactions that take place in the oral cavity and examine how these interactions change from healthy (eubiotic) to disease (dysbiotic) states. We further discuss the dysbiotic signatures associated with periodontitis and caries and their sequalae, (e.g., tooth/bone loss and pulpitis), and the systemic diseases associated with these oral diseases, such as infective endocarditis, atherosclerosis, diabetes, Alzheimer's disease and head and neck/oral cancer. We then discuss current computational techniques to assess dysbiotic oral microbiome changes. Lastly, we discuss current and novel techniques for modulation of the dysbiotic oral microbiome that may help in disease prevention and treatment, including standard hygiene methods, prebiotics, probiotics, use of nano-sized drug delivery systems (nano-DDS), extracellular polymeric matrix (EPM) disruption, and host response modulators.

https://escholarship.org/content/qt68k197wb/qt68k197wb.pdf?t=qr2w5i

The oralome and its dysbiosis: New insights into oral microbiome-host interactions

Obesity is considered an important factor that increases the risk of colorectal cancer (CRC). So far, the association of gut microbiota with both obesity and cancer has been described independently. Nevertheless, a specific obesity-related microbial profile linked to CRC development has not been identified. The aim of this study was to determine the gut microbiota composition in fecal samples from CRC patients with (OB-CRC) and without obesity (L-CRC) compared to the microbiota profile present in non-obese healthy controls (L-HC), in order to unravel the possible relationship between gut microbiota and microbial-derived metabolite trimethylamine N-oxide (TMAO), the inflammatory status, and the intestinal permeability in the context of obesity-associated CRC. The presence of obesity does not induce significant changes in the diversity and richness of intestinal bacteria of CRC patients. Nevertheless, OB-CRC patients display a specific gut microbiota profile characterized by a reduction in butyrate-producing bacteria and an overabundance of opportunistic pathogens, which in turn could be responsible, at least in part, for the higher levels of proinflammatory cytokine IL-1β, the deleterious bacterial metabolite TMAO, and gut permeability found in these patients. These results suggest a possible role of obesity-related gut microbiota in the development of CRC, which could give new clues for the design of new diagnostic tools for CRC prevention.

https://www.mdpi.com/1422-0067/21/18/6782/pdf

Gut Microbiota-Mediated Inflammation and Gut Permeability in Patients with Obesity and Colorectal Cancer.

Colorectal cancer (CRC) is the third most diagnosed type of cancer worldwide. Dietary features play an important role in its development, and the involvement of human microbial communities in this pathology has also recently been recognized. Individuals with CRC display alterations in gut bacterial composition and a notably higher abundance of putative oral bacteria in colonic tumors. Many experimental studies and preclinical evidence propose that dietary polyphenols have a relevant role in CRC development and progression, mainly attributed to their immunomodulatory activities. Furthermore, polyphenols can modulate oral and gut microbiota, and in turn, intestinal microbes catabolize polyphenols to release metabolites that are often more active and better absorbed than the original phenolic compounds. The current study aimed to review and summarize current knowledge on the role of microbiota and the interactions between dietary polyphenols and microbiota in relation to CRC development. We have highlighted the mechanisms by which dietary polyphenols and/or their microbial metabolites exert their action on the pathogenesis and prevention of CRC as modulators of the composition and/or activity of oral and intestinal microbiota, including novel screening biomarkers and possible nutritional therapeutic implications.

/pdf/interplay-between-dietary-polyphenols-and-oral-and-gut-1m4byexnlq.pdf

Interplay between Dietary Polyphenols and Oral and Gut Microbiota in the Development of Colorectal Cancer.

Background: Hundreds of studies have found that the microbiota contributes to the development of gastric cancer in the past two decades. This study aimed to access the research trends of microbiota and gastric cancer. Materials and Methods: Publications from January 1, 2000 to December 31, 2019 were retrieved from the Web of Science Core Collection database and screened according to inclusion criteria. Different kinds of software, SPSS21.0, HistCite, VOSviewer, CiteSpace, and the online bibliometric analysis platform were used to evaluate and visualize the results. Results: A total of 196 publications were finally identified, and the annual number of publications showed an increasing trend. These publications were from 44 countries and the USA showed its dominant position in publication outputs, H-index, total citations, and international collaborations. The journal of Helicobacter was the most productive journal. Correa P and Peek RM published the most papers, and the most productive institution was Vanderbilt University. The keyword of "Helicobacter pylori" ranked first in research frontiers and appeared earlier, and the keyword of "microbiota" began to appear in the past 3 to 5 years. Conclusion: The annual number of publications would continue to grow. Besides the traditional Helicobacter pylori related researches, future research hotspots will focus on microbiota and its mechanism of action.

/pdf/research-trends-on-the-relationship-between-microbiota-and-4ssya5y7dq.pdf

Ting-Ting Li

Papers

The role of Fusobacterium nucleatum in colorectal cancer: from carcinogenesis to clinical management.