Mariana X. Byndloss, DVM, PhD, assistant professor, pathology, microbiology and immunology, Vanderbilt University Medical Center, discusses how the gut microbiome influences human health, highlighting the relationship between the gut microbiome and a person’s risk for developing gastrointestinal cancers, as well as characteristics of a healthy gut microbiome.A growing body of evidence indicates that the microbes that live in the human gut are important for maintaining health, Byndloss says, adding that these microbes are also important for the development of different diseases. As investigators have continued to study the characteristics of healthy microbiota, they have found critical signatures of healthy microbial communities, Byndloss explains. One of these signatures is the dominance of obligate anaerobic bacteria, including bacteroides species, which are bacteria that thrive in environments without oxygen, Byndloss says.

Bacteroides species promote health in multiple ways, such as by digesting components of the diet that humanscannot digest themselves, such as fiber, Byndloss expands. It is commonly understood that humans need a diet that is rich in fiber and vegetables because these contain nutrients that feed the beneficial microbes, which produce molecules to prevent inflammation and disease, Byndloss emphasizes.

However, investigators have found correlations between several human diseases and decreases in the dominance of the obligate anaerobic bacteria, which lead to expansions, or blooms, of other types of microbes, Byndloss says. These microbes are facultative anaerobic microbes, such as proteobacteria or enterobacteria acid, Byndloss continues. Examples of facultative anaerobic microbes include escherichia coli and salmonella typhimurium, which can cause disease, she says. This expansion of microbes is seen after treatment with antibiotics, as well as in multiple human diseases, ranging from necrotizing enterocolitis in infants, to inflammatory bowel disease, to colorectal cancer, Byndloss explains. The expansion of these microbes may be a critical sign of an issue within the intestinal microbiota, she concludes.

Videos

Mariana X. Byndloss, DVM, PhD, discusses how the gut microbiome influences human health, highlighting the relationship between the gut microbiome and a person’s risk for developing gastrointestinal cancers, as well as characteristics of a healthy gut microbiome.


Dr Byndloss on the Relationship Between the Gut Microbiome and GI Cancers

Mariana X. Byndloss, DVM, PhD, assistant professor of pathology, microbiology and immunology, Vanderbilt University Medical Center, discusses the relationship between the gut microbiome and the risk of developing cancers such as colorectal cancer (CRC).

An increasing body of evidence has elucidated a potential role for gut microbiomes in the development and successful treatment of certain cancers, Byndloss begins. The interaction between diet and the health of commensal gut bacteria is one particular way that gut health may influence cancer susceptibility both in and outside of the gastrointestinal tract, Byndloss states.

High-fat diets have been shown to drive tumorigenesis by inducing microbial dysbiosis and metabolic dysregulation, altering the level of metabolites, and causing gut barrier dysfunction in colonic carcinogenic mouse models. Other potential functional contributions to cancer etiology include the ability of gut bacteria to harvest inaccessible nutrients from the diet such as fiber, their ability to prevent the metabolism of certain cancer treatments, and their influence on immune system activation and systemic inflammation.

The health of gut microbiota has been linked to the development of CRC, Byndloss continues. Proinflammatory microbes can increase inflammatory tone in the intestines, which increases risk, she says. Furthermore, many microbes produce metabolites that directly promote carcinogenesis. For example, some strains of E.Coli carry the pathogenicity island pks, which encodes for a gene known as colibactin, Byndloss states. Once synthesized, colibactin causes double-stranded DNA breakage and can lead to cell cycle arrest for eukaryotic cells, and apoptosis in immune cells, Byndloss explains. The mutational signature induced by this genotoxin has also been implicated in the development of CRC, Byndloss adds.

Other obligate anaerobic, Gram-negative microbes such as Fusobacterium and Bacteriodes fragilis also have shown direct carcinogenic potential because of their metabolites on epithelial cells in the intestines, Byndloss concludes.

Mariana X. Byndloss, DVM, PhD, discusses the relationship between the gut microbiome and the risk of developing cancers such as colorectal cancer.

Mariana X. Byndloss, DVM, PhD

Articles

Dr Byndloss on the Relationship Between the Gut Microbiome and GI Cancers

Dr Byndloss on the Relationship Between Gut Health and the Risk of Developing CRC

Mariana X. Byndloss, DVM, PhD

Articles

Dr Byndloss on the Relationship Between the Gut Microbiome and GI Cancers

​​Dr Byndloss on the Relationship Between Gut Health and the Risk of Developing CRC

Dr Byndloss on the Relationship Between Gut Health and the Risk of Developing CRC