Effect of L-thyroxine treatment on peripheral blood dendritic cell subpopulations in patients with Hashimoto’s thyroiditis

Abstract

Recent reports suggested dendritic cells (DCs) to be important players in the pathogenesis of autoimmune thyroid processes in humans. However, there are virtually no data addressing the influence of thyroid autoaggression-associated disturbances of thyrometabolic conditions on DCs biology. The aim of the study was to evaluate the influence of L-thyroxine supplementation on conventional and plasmacytoid peripheral blood DCs subtypes in patients with hypothyroidism due to Hashimoto's thyroiditis (HT). Eighteen patients with newly diagnosed hypothyroidism due to HT were included into the study. All patients received L-thyroxine treatment with doses adjusted to reach euthyroidism. Peripheral blood DC subtypes structure and immunoregulatory phenotype were analyzed by flow cytometry in the same patient prospectively at two time points: (i) before and (ii) 3 months after beginning of L-thyroxine treatment (hypothyroidism vs. euthyroidism, respectively). Percentage of plasmacytoid DCs in peripheral blood mononuclear cells fraction was significantly decreased in the course of L-thyroxine treatment (0.27 ± 0.19 vs. 0.11 ± 0.08; p < 0.05), whereas we did not observe any changes in the number of conventional DCs. However, the phenotypic analysis showed a significant increase of conventional DCs expressing CD86 and CD91 (64.25 ± 21.6% vs. 86.3 ± 11%; p < 0.05 and 30.75 ± ± 11.66% vs. 44.5 ± 13.3%; p < 0.05; respectively) in euthyroid patients. Standard L-thyroxine supplementation in HT patients exerted significant immunoregulatory effects, associated with quantitative and phenotypic changes of peripheral blood DC subpopulations.

Thyroid Hormone Action on Innate Immunity

“…Dedecjus et al (103) reported that the thyrometabolic state influenced the major human peripheral blood DCs, pDCs, and cDCs, with T4 substitution to thyroid cancer patients after surgery increasing the frequency of these cells and the expression of CD86 and HLA-DR (activation markers). In hypothyroid patients with Hashimoto's Thyroiditis, T4 supplementation exerted changes of peripheral blood DC subpopulations, with increased expression of costimulatory molecules (104). Although TRs in human DC populations have not yet been found, increased expression of CD86 by T3 addition to cell cultures of human peripheral blood pDCs was reported (103).…”

Recombinant Human Thyroid-Stimulating Hormone Increases the Percentages of Natural Killer T Cells and B Lymphocytes in Human Peripheral Blood In Vivo

“…However, the effect of L-T4 supplementation was different in patients with Hashimoto's disease. In this group of patients, the level of pDCs in the PBMC fraction decreased during the L-T4 treatment, while the percentage of cDCs remained unchanged (36).…”

Autoimmunity, New Potential Biomarkers and the Thyroid Gland—The Perspective of Hashimoto’s Thyroiditis and Its Treatment

“…On the other hand, the results of different study have suggested the presence of the direct effect of L-thyroxine therapy on the percentages of selected populations of dendritic cells (DCs), with a significant reduction among their plasmacytoid subtype in peripheral blood and no changes concerning the total number of conventional DCs. However, the cluster of conventional DCs expressing CD86 and CD91 was shown to have a greater percentage [51]. The normalization of serum TSH level doses does not have to optimize serum T3; it concerns particularly individuals with a decreased effectiveness of conversion between T4 and T3.…”