The gut microbiome of people with inflammatory bowel disease (IBD) fluctuates more compared to those of healthy individuals. These findings suggest that therapies targeting some of these alterations within the gut microbes may prove beneficial to IBD patients.
The study, “Dynamics of the human gut microbiome in inflammatory bowel disease,” was published in the journal Nature Microbiology.
IBD is partially caused by a deregulated immune response, which in many cases is activated due to alterations in the natural community of microbes that populate our gut, called gut microbiome. Previous studies showed differences in the gut microbiome composition not only between IBD and healthy people, but even within different IBD subtypes, including ulcerative colitis, colonic Crohn’s disease, and ileal Crohn’s disease.
However, all these studies were performed at a specific time point or with few individuals, and the gut microbiome fluctuations over the long term remained poorly understood.
“It’s important to know not just what microbes are present, but also to understand how the microbial community changes as patients’ symptoms improve or worsen over time,” Colin Brislawn, a scientist at the Pacific Northwest National Laboratory (PNNL) and one of the study’s authors, said in a press release. “We explored the dynamic nature of the disease as it relates to the dynamic nature of the human gut microbiome.”
The international team of researchers analyzed the gut microbiome in 137 people over two years. The group included patients with ulcerative colitis (UC), colonic Crohn’s disease, ileal Crohn’s disease, and healthy individuals, or controls.
To analyze the community of microbes, the team collected participants’ fecal material every three months for up to two years. Researchers also registered the patients’ symptoms and disease progression.
After collection, which accounted for a total of 683 fecal samples, scientists performed genomic sequencing to identify which microbes were present in each sample.
Healthy individuals exhibited a more constant and stable microbial gut community, while that of IBD patients suffered huge shifts. In fact, researchers found that in IBD there were periods in which certain bacteria disappeared completely. This phenomenon, however, was rarely detected in healthy people. In the course of a few months, different microbes replaced a great portion of the IBD patients’ microbiome.
Surgical interventions and medication were two parameters the team found that also promoted alterations to the gut microbiome. The more pronounced alterations were detected in patients with ileal Crohn’s disease who underwent surgery to remove part of their intestine. Medication such as steroids was also associated with more fluctuations. Patients experiencing a flare-up in their symptoms were also more likely to suffer sudden changes in their gut microbiome.
“The results are an important step in our aim to understand how the microbiome relates to the dynamics of inflammatory bowel disease,” concluded gastroenterologist Jonas Halfvarson of Örebro University in Sweden.
“Ultimately, manipulation of the microbiome, aiming to mimic the situation and the trajectories of healthy individuals, might become an attractive treatment strategy to maintain IBD patients in remission, especially if immunosuppressants such as corticosteroids can be avoided,” he wrote.