A new study by the University of Chicago and Stanford University on pairs of twins with and without food allergies has identified potential microbial actors in this condition. The results are published in the Journal of Clinical Investigation.
The study arose from previous research at Nagler’s laboratory in UChicago on the fecal microbiota in infants. By transplanting stool microbes from healthy and food-allergic infants into germ-free mice (which do not have a microbiome), the researchers found that the healthy infant microbiota protects against the development of food allergies.
“In this study, we looked at a more diverse population across a wide range of age groups,” said Cathryn Nagler, a professor at UChicago. “By studying pairs of twins, we had the advantage of studying genetically identical individuals who were raised in the same environment, which enabled us to analyze the influence of genetic and environmental factors.”
After a discussion at a research conference, Nagler and her colleague in Stanford, Dr. Kari Nadeau to work together on the project. Nadeau, the director of the Sean N. Parker Center for Allergy and Asthma Research, had conducted a study on the epigenetics of food allergies and had already collected stool samples from study participants. Nagler’s laboratory performed the sequencing on the samples taken from 13 pairs of twins with and without food allergies and another five pairs of twins in which both twins had at least one food allergy.
The research team examined which microbes were present in the stool samples as well as which metabolic products (so-called metabolites) that come not only from the microbes, but also from host and food sources.
“We urgently need biomarkers to understand the immunoregulatory function of intestinal bacteria,” said Nagler. “Metabolites give us clues about what bacteria do mechanistically to regulate the immune response.”
This approach identified 64 different sets of bacterial species and metabolites that distinguish the healthy and allergic twin groups. Most of these variable abundance bacteria belonged to the Clostridia class, which several previous reports from the Nagler laboratory showed to protect against food allergies. The accumulation of allergy-protecting bacteria in the healthy twins, which was presumably detected in early life, persisted into adulthood despite separation and lifestyle changes. In addition, healthy twins showed an enrichment of the diacylglycerol metabolic pathway and two specific bacteria: Phascolarctobacterium faecium and Ruminococccus bromii.
“One dimension of data is not enough to narrow down thousands of bacteria in certain species as candidates for future therapeutic interventions – merging data from multiple dimensions is key,” said lead author Riyue Bao, now a research fellow at Medicine the University of Pittsburgh. “In our study, we took advantage of both high-throughput microbiome sequencing and metabolic profiling techniques and were able to nominate two specific species, each involved in different metabolic pathways that can be prioritized as potential targets for future research and therapeutic interventions in food allergies.”
“Countless people will go to Google and want to know, ‘Should I eat yogurt? Should I not eat yogurt? Does my microbiome play a role in my disease?'” Said Nadeau. “This research is important as one of the most important building blocks for the knowledge of the human microbiome that must be established in order to answer these questions. We cannot yet say that this is a cause and effect relationship, but we can say that this is the case. ” a connection with illness and health. Now we can ask ourselves what that means. “
While the study only included a small group of participants, the researchers are excited about the results and their application to future projects.
Future research will examine the specific roles of these bacteria in food allergies. For example, R. bromii is a key species in breaking down resistant starch – food starch that normally escapes digestion. Nagler plans to investigate how a resistant starch supplement can affect the presence of R. bromii in the fecal microbiome and whether or not this can increase the response to oral immunotherapy, the only treatment currently available for food allergies.
Courtesy of the University of Chicago Medical Center.
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