Five-minute Microbiome Science Roundup: May 2019

This month’s roundup includes a study on a unique gut-microbiota-modulating dietary intervention (vegetables rich in inulin-type fructans), and a study on how gut microbiota might predict Crohn’s disease recurrence after ileal resection. Furthermore, several different papers on the gut microbiome in irritable bowel syndrome (IBS) were published in the scientific literature, each with a different approach. And the end of the month brought a major update on the second phase of the Human Microbiome Project, with four papers published in Nature about the various project activities.

Effects of a diet based on inulin-rich vegetables on gut health and nutritional behavior in healthy humans: A group led by Nathalie Delzenne took on the difficult task of studying a prebiotic dietary intervention in healthy individuals. Their approach was to measure not only gastrointestinal symptoms, but also food-related thoughts / behaviors. They discovered when healthy people consumed vegetables rich in inulin-type fructans, they reported higher satiety and less desire to eat foods that were sweet or salty—and somewhat surprisingly, these feelings persisted for several weeks after the intervention was complete. The intervention also reduced gut microbiota richness and induced changes in particular microbial taxa.

Prominence of ileal mucosa-associated microbiota to predict postoperative endoscopic recurrence in Crohn’s disease: When someone with Crohn’s disease undergoes ileal resection, predicting the recurrence of disease is currently difficult. This group looked at the gut microbiota of patients at the time of surgery, and found certain bacterial taxa that appeared to predict disease relapse.

Irritable bowel syndrome (IBS) is diagnosed based on reported symptoms rather than any confirmatory biological measurements. Yet the paradigm might be about to change, with many research groups investigating the gut microbiome and other biological parameters in those with IBS, with the hope of finding an IBS biomarker or biomarkers. Several papers published in May looked at different ways to distinguish people with IBS from healthy individuals:

Small intestinal microbial dysbiosis underlies symptoms associated with functional gastrointestinal disorders: These researchers found that the composition of the small intestinal microbiota – while difficult to sample – correlates better with IBS symptoms than does a duodenal aspirate culture. And sure enough, a dietary intervention that triggered gut IBS symptoms also had pronounced effects on small intestinal microbes.

Metabolomics reveals elevated urinary excretion of collagen degradation and epithelial cell turnover products in irritable bowel syndrome patients: This small study found a panel of ten metabolites in the urine that seemed to distinguish people with IBS from people without IBS. (A limitation of this study was that the participants had many different co-morbid conditions.)

Leveraging Human Microbiome Features to Diagnose and Stratify Children with Irritable Bowel Syndrome: This month’s IBS papers were topped off by a sophisticated multi-omics analysis in IBS from collaborators at Baylor College of Medicine (USA). In a population of children aged 7 to 12, these researchers found gut bacterial taxa, genes / pathways, and metabolites that could combine to identify those with IBS. They even found specific ones that were associated with abdominal pain, the main troubling symptom in children with IBS.

The US-based Human Microbiome Project (HMP) was one of the world’s important initial microbiome research endeavours. Phase one of the HMP profiled the microbiomes of healthy individuals, while phase two, called HMP2 or the Integrative Human Microbiome Project (iHMP), focused on several different disease areas as reported in the papers below.

The Integrative Human Microbiome Project: This paper gives an overview of what was explored in the iHMP, including the resources that were produced as part of the project.

Multi-omics of the gut microbial ecosystem in inflammatory bowel diseases: This work is the most extensive characterization to date of individuals with inflammatory bowel disease (IBD): researchers tracked 132 people with IBD over the course of a year, collecting stool, biopsy, and blood samples for multi-omics analysis. Periods of increased disease activity are notoriously hard to predict in IBD, but promisingly, in this cohort they were associated with changes in gut microbiota taxa, functions, and other markers

The vaginal microbiome and preterm birth: This study shows vaginal bacterial taxa that were found to differ in a cohort of women who gave birth to preterm infants versus those who carried their babies to term.

Longitudinal multi-omics of host–microbe dynamics in prediabetes: 106 people who were healthy or who had prediabetes were followed for four years—and researchers tracked their health status along with almost everything else imaginable: their microbiomes, transcriptomes, metabolomes, proteomes, and cytokines. Interesting patterns were observed with respiratory infections and flu immunizations, and the investigators noted different host–microbe associations in people who were insulin resistant versus those who were insulin sensitive.

Kristina Campbell

Microbiome Science Writer

The Microbiome Times