Gut microbes may play role in Graves’ disease diagnosis, thyroid autoimmunity
The abundance and diversity of intestinal microbiota are reduced in adults with Graves’ disease, and Lactobacillus may be one of the pivotal factors activating autoimmune response, according to data published in Thyroid.
In an analysis of fecal samples collected from participants with untreated Graves’ disease as well as healthy volunteers, researchers also found that nine significant genera are “promising” as microbial markers to distinguish those with Graves’ disease from healthy controls.
“The characteristics of the composition, abundance and diversity of the gut microbiota identified in this study may be beneficial to provide new insights into the pathogenesis of Graves’ disease, as well as new ideas for microecological therapies, such as probiotics or prebiotics for Graves’ disease,” Dan Li, MD, PhD, vice director of the department of nuclear medicine department, associate chief physician and associate professor at Shanghai Tenth People’s Hospital and Tongji University School of Medicine, China, told Healio.
In a cross-sectional study, Li and colleagues analyzed 16S ribosomal RNA V3-V4 DNA regions of microbiota, obtained from fecal samples collected from 45 patients with untreated Graves’ disease (33 women; median age, 37 years) and 59 healthy controls (37 women; median age, 43 years), matched by age and sex. Researchers used high-throughput sequencing to assess microbial differences between the two groups.
Compared with controls, those with Graves’ disease had reduced alpha diversity (P < .05). At the phylum level, adults with Graves’ disease had a lower proportion of Firmicutes (P = .008) and a higher proportion of Bacteroidetes (P = .002) compared with controls. At the genus level, those with Graves’ disease had greater numbers of Bacteroides and Lactobacillus, although fewer Blautia, [Eubacterium] hallii group, Anaerostipes, Collinsella, Dorea, unclassified f Peptostreptococcaceae and [Ruminococcus] torques group vs. controls (P < .05 for all).
“Alpha diversity analysis at the operational taxonomic units level revealed that Graves’ disease patients have a significantly reduced richness of gut microbiota compared with healthy controls,” the researchers wrote. “Similar findings have been observed in inflammatory bowel disease, hypertension and autoimmune hepatitis. It is thought that lower alpha diversity may lead to a decline in the host’s immune function and is associated with an inflammatory response.”
In subgroup analyses, researchers found that Lactobacillus may play a key role in the pathogenesis of autoimmune thyroid diseases. Nine distinct genera showed significant correlations with certain thyroid function tests. Additionally, functional prediction revealed that Blautia may be an important microbe in certain metabolic pathways that occur in the hyperthyroid state.
“We will continue to expand the sample size and combine metagenomics and metabolomics to validate the changes in intestinal microbiota and metabolites in patients with Graves’ disease from a multi-omics perspective,” Li said. “Second, we intend to further validate the correlation between patients with Graves’ disease and intestinal microbiota through fecal microbiota transplantation. Third, we propose to select the significant bacteria in the study for refined mechanistic studies.”
For more information:
Dan Li, MD, PhD, can be reached at firstname.lastname@example.org.