The gut is home to a community of microbes, the microbiome, which plays a major role in human health and disease. While some of those bacteria and microorganisms are beneficial, others can pose problems. New research has indicated that a common toxin made by the common intestinal bacterium Escherichia coli, microcin B17, is connected to inflammatory bowel disease (IBD), a collection of illnesses that includes ulcerative colitis and Crohn’s disease. An international group of researchers from the John Innes Centre in Norwich, UK, and Brigham and Women's Hospital in Boston, USA have reported these findings in Cell.
The work was the result of a serendipitous observation made while scientists were trying to develop new antibiotics. It will open up new treatment avenues for IBD patients. E. coli typically makes microcin B17 toxin to battle and dominate other bacteria.
“This is largely a chance finding. We have been studying this toxin for its antibacterial properties, and we were contacted by Professor Richard Blumberg who leads the Boston group for quite different reasons - they thought there might be a connection between the toxin and IBD,” explained Professor Tony Maxwell.
The investigators collaborated to show that as the toxin breaks down, the byproducts that are created can cause inflammation in the gut, which is a big factor in IBD. In addition, the study found that one type of aromatic organic compounds, the oxazole class, is a trigger of gastrointestinal inflammation that is caused by microbes and the environment.
“These findings will advance our understanding of how gut inflammation associated with IBD may be triggered and offer new hope of potential future therapy,” said Dr. Fred Collin, a postdoctoral fellow who was a key part of the research in Professor Maxwell's lab.
Genetic tools like genome-wide association studies, which identify links between changes in genes and physiological conditions, have helped elucidate some of the genetic causes of IBD. Environmental contributions and patient reactions have not been clearly defined yet.
"The bacteria that live inside us have a lot of impact on well-being and the twist here is that it's not the E. coli bacteria but the toxin that's produced by the bacteria that appears to have an effect," explained Maxwell. "They produce these toxins to kill their neighbors in their fight for ecological niches but it appears that the breakdown products of the toxin can initiate gut inflammation," he added.
This work adds to the growing body of evidence illustrating the connection between the microbes in our gastrointestinal system and our health. Learn more about the gut microbiome from the video.