INTRODUCTION: The balance of gut microbiome is associated with the immunologic and metabolic homeostasis in various pathophysiology such as obesity and autoimmune diseases. However, the characteristics and the clinical relevance of gut microbiome in autoimmune thyroid disease are undetermined. This study aimed to determine the characteristics of the gut microbiome in Graves’ disease (GD) patients.
METHODS: Untreated GD patients who visited a single tertiary center from April-2018 to March- 2019 were recruited. The fecal samples were collected and freshly analyzed by 16S rRNA gene sequencing. Patients who had euthyroidism with less than 10mg/day of antithyroid drugs at 6 month were defined as good response. Additionally, patients were divided into three groups according to the weight changes at 6 month: <1kg, 1-3kg, and > 3kg.
RESULTS: A total of 31 GD patients were recruited. The mean age was 40.8 ± 12.3 years and 87% was female. Compared to the healthy controls, GD patients showed significantly lower microbial richness and higher firmicutes to bacteroidetes ratio. Patients with good response to treatment showed higher dysbiosis index and relative abundance of pathobiont than others. Interestingly, patients with lower microbial richness and higher dysbiosis index showed bigger weight gain (P for trend <0.05). The relative abundance was higher in Clostridium_g24 and Lactobacillus rogosae and lower in Dialister and Oscillibacter in patients with weight gain >3kg than others.
CONCLUSION: Higher index of dysbiosis in untreated GD patients was associated with good treatment response and higher weight changes. Pre-treatment status of gut microbiome may be used for predicting clinical outcomes in GD patients.