Gut microbiome and thyroid diseases

The human microbiome constitutes an integral part of health. In particular, it is quite necessary for the development, differentiation and maturation of the immune system, 70% of which resides in the intestinal mucosa. Microbiome studies until now revealed an association between disturbance of microbiota (dysbiosis) and various pathological disorders including changes in host immune status. Autoimmune thyroid diseases are one of the most common organ-specific autoimmune disorders with a worldwide prevalence higher than 5%. Among the latters, those that predominate are Hashimoto's thyroiditis and Graves' disease. Several factors have been studied such as genetic and environmental ones. According to recent studies, it is assumed that gut microbiome might play a significant role in triggering autoimmune diseases of the thyroid gland. However, the exact etiology has not been elucidated yet. The present review aims to describe the work done so far regarding the role of gut microflora in the pathogenesis of au-toimmune thyroid diseases and its involvement in the appearance of benign nodules and papillary thyroid cancer. It appears that future work is needed to elucidate more precisely the mechanism of involvement of gut microbiota to the development of autoimmune thyroid diseases.