Alterations of the Gut Microbiota in Hashimoto’s Thyroiditis Patients Original paper

What was studied?

Gut microbiota alterations in Hashimoto’s thyroiditis (HT) were the focus of this original research article. The study used 16S rRNA sequencing to characterize microbial community structure in fecal samples from euthyroid HT patients compared with matched healthy controls, generating insights into microbial associations linked to autoimmunity. The exploration includes differences in bacterial diversity, shifts in the Firmicutes/Bacteroidetes ratio, and the emergence of distinctive microbial signatures with potential diagnostic relevance. This work directly supports the development of a microbiome signatures database by identifying reproducible microbial taxa patterns associated with autoimmune thyroid disease.

Who was studied?

The study analyzed two cohorts totaling 77 adults of Han Chinese origin from northeastern China. The exploration cohort included 28 HT patients and 16 healthy controls; the validation cohort consisted of 22 HT patients and 11 controls. All HT subjects were euthyroid and newly diagnosed. Individuals with autoimmune, metabolic, infectious, gastrointestinal, or recent antibiotic-related confounders were excluded. Clinical variables measured included TPO-Ab, TG-Ab, FT3, FT4, TSH, BMI, and demographic information, allowing correlation analyses between microbial patterns and thyroid autoimmunity.

Most important findings

HT patients exhibited significant gut microbiota compositional shifts without reduced alpha diversity. Principal coordinate analysis showed clear separation between groups, indicating distinct microbial community structure. A marked increase in the Firmicutes/Bacteroidetes ratio was observed in HT patients (9.53 vs. 3.18), a pattern also noted in inflammatory and autoimmune conditions. Several genera demonstrated great, disease-associated directional changes. Genera decreased in HT included Bacteroides, Faecalibacterium, Prevotella_9, and Lachnoclostridium—organisms with known roles in short-chain fatty acid production, mucosal barrier protection, anti-inflammatory signaling, and immune regulation. Genera increased in HT included Blautia, Roseburia, Ruminococcus torques group, Fusicatenibacter, Romboutsia, Dorea, and Eubacterium hallii group, some of which are linked to mucin degradation, metabolic inflammation, or disease-associated shifts in other autoimmune disorders. Correlations with TPO-Ab and TG-Ab underscore a relationship between dysbiosis and autoimmune activity. A classifier based on the top 10 discriminant genera achieved AUC values of 0.91 (exploration) and 0.88 (validation), indicating strong diagnostic potential.

Key implications

The research highlights a consistent dysbiotic signature in HT independent of thyroid hormone status, pointing toward microbial contributions to autoimmune pathophysiology. The reduced abundance of barrier-supportive and anti-inflammatory taxa suggests impaired mucosal homeostasis, while increases in mucin-degrading and proinflammatory organisms imply heightened intestinal immune activation. These patterns support hypotheses involving gut permeability, microbial antigen mimicry, and dysregulated T-cell responses in HT. The study also demonstrates that gut microbiota profiling may aid early or noninvasive HT diagnosis, though larger, longitudinal, and mechanistic studies are needed to clarify causality and therapeutic potential.

Citation

Zhao F, Feng J, Li J, et al. Alterations of the gut microbiota in Hashimoto’s thyroiditis patients.Thyroid. 2018. doi:10.1089/thy.2017.0395