Thyroid peroxidase antibodies: prevalence and assessment of immunological parameter in the context of search for new predictive markers of hypothyroidism

BACKGROUND: The annual increase in the incidence of autoimmune pathologies, including autoimmune thyroiditis (AIT), emphasizes the relevance of studying the causes of their development and preventive measures. Despite the availability of analysis of antibodies to thyroid peroxidase (TPO), problems remain in accounting for statistical data on the prevalence of AIT. The importance of fundamental research in the search for prognostic markers of the progression of euthyroid carriage of antibodies to TPO to hypothyroidism lies in the need to determine the key molecular mechanisms for the development of more effective diagnostic and preventive strategies.

AIM: To assess the prevalence of TPO antibody carriage and to search for relationships between immunological parameters and the degree of thyroid dysfunction in AIT.

MATERIALS AND METHODS: The study involved 580 people over 18 years of age. The following data were analyzed: laboratory and instrumental data (blood test for thyroid-stimulating hormone, free thyroxine, antibodies to TPO); thyroid ultrasound data; anamnestic and immunological study data (regulatory T cells, regulatory B cells, B10 lymphocytes, interferon γ, interleukin (IL) IL-17, IL-4-producing T lymphocytes).

RESULTS: Positive titers of antibodies to TPO were detected in 143 individuals (24.7%), of which 73 patients (51.41%) had concomitant thyroid nodules and 60 patients (41.96%) had hypothyroidism. Statistically significant differences were obtained between carriers of antibodies to TPO and conditionally healthy individuals in the concentration of thyroid stimulating hormone, the presence of ultrasound signs of autoimmune changes and the presence of three or more children in the anamnesis (p <0.001). It was found that the concentration of antibodies to TPO statistically significantly correlated with the presence of many children (p=0.037). In the group of carriers of antibodies to TPO, a difference was found in the content of regulatory B cells during in vitro incubation with additional activation compared to healthy donors (p=0.039). However, reduced expression of IL-10 by these cells was not observed. No statistically significant differences in the content of regulatory T cells were found in the study groups; however, when a specific activator was added, a reduced degree of induction of these cells was observed, indicating their possible weakened functional activity, leading to disturbances in the control of autoaggression and suppression of autoreactive reactions.

CONCLUSION: The frequency of TPO antibody carriage is 24.6%. Women with many children have a significantly higher prevalence of AIT and statistically significantly higher titers of TPO antibodies in the blood, which allows us to consider having many children as a risk factor for the development of AIT. The study showed the expected difference in the number of regulatory B cells in TPO antibody carriers, but no reduced induction of IL-10 was observed. Further fundamental studies with larger target samples of individuals with AIT are needed in the search for new prognostic markers of the development and progression of the disease.