Prior studies have found a correlation between inflammatory bowel disease (IBD) and colorectal cancer; those with IBD are at an increased risk of developing this cancer compared to the general population. But why is this? According to an article in Live Science, new research suggests that genotoxins produced by gut bacteria could play a role. 

Researching Genotoxins 

Genotoxins are chemical agents that can damage chromosomes and DNA. In the past, Escherichia coli (E. coli), which produces genotoxins called colibactin, have been linked to IBD. Colibactin has also shown to cause tumors in mice models. 

In the study, which was published in Science, the research team discovered a class of genotoxins that had never previously been known or described: “indolimines,” produced by Morganella morganii (M. morganii). M. morganii is often found in the gut of patients with inflammatory bowel disease.

To begin, the researchers sourced stool samples from eleven individuals with IBD. Next, they screened over one hundred different gut bacteria found within these samples. Eventually, the researchers focused on eighteen specific strains to see which damaged DNA. 

This led them to M. morganii and, through this, the discovery of indolimines. Further, the researchers found that the aat gene creates indolimines. To determine the effects of indolimines, researchers evaluated mice models of colorectal cancer. When introducing aat-associated M. morganii bacteria to the mice, tumors grew faster and more aggressively. But when the team removed the gene, tumor growth stopped. 

Ultimately, this is an interesting association between this bacteria, IBD, and colorectal cancer. However, more research is needed to better understand:

• How indolimines influence or drive cancer
• Whether there are any interventions which could reduce the risk of cancer development
• What role this bacterium plays in the various forms of IBD (such as Crohn’s disease and ulcerative colitis) 

An Overview of Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease refers to a group of conditions characterized by chronic digestive tract inflammation. While this condition can be mild for some, it can be debilitating for others. Additionally, complications of IBD can be life-threatening, so it is important to maintain adequate treatment and care. Doctors are unsure of the exact cause of IBD. However, many surmise that an immune malfunction and some sort of trigger could cause IBD. IBD is most common in people under age 30, Caucasian individuals, those of Ashkenazi Jewish descent, cigarette smokers, and those living in an industrialized country. 

IBD is a variable condition. Symptoms can (but do not always) include:

• Fatigue
• Abdominal pain and cramping
• Bloody stool
• Diarrhea
• Gas and bloating
• Joint pain
• Nausea and vomiting
• Fever
• Appetite loss
• Unintended weight loss
• Colon cancer (complication)
• Blood clots (complication)
• Eye, skin, and joint inflammation (complication)