Autoimmune thyroid diseases (AITDs) are chronic autoimmune disorders that cause impaired immunoregulation, leading to specific immune responses against thyroid antigens. Graves’ disease (GD) and Hashimoto’s thyroiditis (HT) are the major forms of AITDs. Increasing evidence suggests a possible role of microbiota alterations in the pathogenesis and progression of AITDs. This systematic review was designed to address the following question: “Is microbiota altered in patients with AITDs?” After screening the selected studies using the inclusion and exclusion criteria, 16 studies were included in this review (in accordance with PRISMA statement guidelines). A meta-analysis revealed that patients with HT showed significantly higher values of diversity indices (except for the Simpson index) and that patients with GD showed significant tendencies toward lower values of all assessed indices compared with healthy subjects. However, the latter demonstrated a higher relative abundance of Bacteroidetes and Actinobacteria at the phylum level and thus Prevotella and Bifidobacterium at the genus level, respectively. Thyroid peroxidase antibodies showed the most significant positive and negative correlations between bacterial levels and thyroid functional parameters. In conclusion, significant alterations in the diversity and composition of the intestinal microbiota were observed in both GD and HT patients.
Rheumatoid arthritis (RA) and autoimmune diseases of the thyroid gland (AITD) often occur together. As autoimmune diseases, they share common pathological pathways, reflecting the fact that the treatment of the underlying disease can influence the course of thyroid disorders. The pharmacotherapy of RA is based on the supply of disease-modifying anti-inflammatory drugs with an increasing focus on biologics. This article aims to review the available literature describing the effects of biological treatments on thyroid function. The use of biologi-cal drugs may have the potential benefit of regulating the level of anti-thyroid antibodies. On the other hand, tumour necrosis factor-alpha (TNF-a) inhibitors are not indifferent to thyroid function and may increase the incidence of subacute thyroiditis. The coexistence of AITD and RA prompts consideration of the need for routine thyroid screening in RA patients and for RA screening in patients with thyroid disease who report joint problems.
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