Aggravates Subclinical Hypothyroidism.

Subclinical hypothyroidism (SCH) has been shown to be associated with microbiota. However, the association between SCH and oral microbiota has not yet been elucidated. The results of our previous clinical studies showed that was abundant in the oral microbiota of SCH patients. This study aimed to investigate the relationship between SCH and oral microbiota, verify the pathogenicity of in SCH, and preliminarily explore the possible mechanism. The SCH mouse model with oral application of was established, and the variance in the mouse oral microbiota and changes in thyroid function and metabolism were detected in mice. Student's test and analysis of variance were used for statistical analysis. Oral application of changed the composition of the oral microbiota of SCH mice, which enhanced the damage to the thyroid and decreased the expression of functional genes of the thyroid. Moreover, decreased oxygen consumption and aggravated glucose and lipid metabolism disorders in SCH mice. Glucose tolerance and insulin tolerance decreased, and the triglyceride content of the liver and inflammatory infiltration in adipose tissue increased in SCH mice after stimulation. Mechanistically, increased the proportion of CD4 T cells in cervical lymph nodes and thyroids in SCH mice. Th1 cells were suggested to play an important role in the pathogenesis of SCH involving . In conclusion, aggravated SCH manifestations, including thyroid dysfunction and glucose and lipid metabolism disorders, by causing immune imbalance in mice. This study sheds new light on the pathogenesis of SCH from the perspective of oral microbiota.