Microbiota Alterations in Patients with Autoimmune Thyroid Diseases: A Systematic Review

Abstract

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.

Causal effect of gut microbiota of Defluviitaleaceae on the clinical pathway of “Influenza–Subacute Thyroiditis–Hypothyroidism”

“…Moreover, the genus is also decreased in the intestines of mice with Grave's ophthalmopathy, which is the progression symptom of Grave's diseases (Masetti et al, 2018 ). Conversely, research also declared a reduction of Bacteroides in Hashimoto's thyroiditis patient fecal samples (Sawicka-Gutaj et al, 2022 ). Bacteroides were also discovered to be positively associated with anti-thyropreoxidase antibodies and negatively associated with thyroid-stimulating hormone levels (Sawicka-Gutaj et al, 2022 ; Fenneman et al, 2023 ).…”

The Role of Toll-like Receptor 2 (TLR2) in the Development and Progression of Hashimoto’s Disease (HD): A Case Study on Female Patients in Poland

“…Studies show that the frequency of developing this disease increases with the age of patients (especially after 60 years of age); however, more and more often, this entity is also diagnosed in young people and even children [ 6 , 7 , 8 , 9 ]. The causes of hypothyroidism and thus the development of HD are many, ranging from genetic factors and hormonal changes to environmental factors, as well as the presence of other comorbidities, especially those of autoimmune origin [ 10 , 11 , 12 , 13 ]. HD itself is classified as a subunit of autoimmune diseases, which means that its development is closely related to the deregulation of the immune system, and, more specifically, to the development of inflammation caused by the host’s immune cells (in particular T lymphocyte-induced apoptosis of thyroid follicular cells) that attack the thyroid [ 14 , 15 , 16 ].…”

Salivary Alterations in Autoimmune Thyroid Diseases: A Systematic Review

“…This evaluation indicates that they are the most common autoimmune disorder affecting humans [ 2 ]. AITD arises due to the loss of tolerance to thyroid antigens in genetically liable individuals in association with environmental factors, such as microbiota alterations [ 3 , 4 , 5 ]. Both manifestations are characterised by infiltration of the thyroid by T and B cells, reactive to thyroid antigens, the production of thyroid autoantibodies and abnormal thyroid functions [ 6 ].…”