“Both the state and the dynamics of the human gut microbiome in healthy individuals are highly personalized. Although cross-sectional studies have revealed dysbiosis of the gut microbiome in IBD, little is known about the individual nature of microbiome dynamics in IBD,” writes Dr. Janet Jannson of the Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory in Richland, Wash.
Dr. Jannson tells Reuters Health that the study, online Feb. 13 in Nature Microbiology, “is the first to look at the long-term dynamics of different types of IBD.”1
The team analyzed the gut microbiome from an IBD cohort of 137 individuals—49 with Crohn’s disease, including inflammation of the ileum or colon; 60 with ulcerative colitis; four with lymphocytic colitis; 15 with collagenous colitis; and nine healthy controls. They collected one to 10 stool samples per participant at three-month intervals for a total of 683 samples.
“We used a mathematical approach to define a ‘healthy plane’ that described the less volatile dynamics of the gut microbiome in healthy individuals compared to individuals with IBD that deviated from the healthy plane,” Dr. Jannson explains by email.
Samples from patients with colonic Crohn’s disease and ulcerative colitis were closer to the healthy plane, and some samples did not differ significantly from healthy controls.
The gut microbiome of individuals with ileal Crohn’s disease varied most from those of healthy individuals, “with large temporal fluctuations in microbial community composition,” Dr. Jannson observes. The variation was especially noticeable in those who had undergone surgical resection, followed by those who did not undergo surgery.
To address the unequal sampling of healthy individuals vs. IBD patients, the team compared the volatility of their healthy controls with healthy participants in two published studies that used different microbiome project datasets. Across all three cohorts, less volatility was observed in healthy individuals compared with those with IBD.
“Monitoring the gut microbiome is a non-invasive approach, and we found it to be a better predictor of IBD disease phenotype than f-calprotectin measurements or human genetic markers,” Dr. Jannson says. “The results of this study are key to precision medicine because the gut microbiome can be used to guide personalized treatment therapies.”
Coauthor Dr. Jonas Halfvarson of Orebro University in Sweden, tells Reuters Health, “From a clinical perspective, our data demonstrate the complexity of IBD and the need to address the dynamics when exploring mechanisms related to disease etiology of chronic diseases … with periods of remissions and episodes of flares.”