New insights into Thyroid Hormone (TH) mechanism of action in Dendritic Cells (DCs): Characterization of TH Transport and Metabolism

GIGENA N; ALAMINO VA; MONTESINOS, MM; NAZAR, M; LOUZADA RA; WAGNER S; MAIA AL; MASINI-REPISO AM; CARVALHO DP; CREMASCHI, G; PELLIZAS CG

Orlando

Congreso; 15th International Thyroid Congress (ITC); 2015

American Thyroid Association

Introduction: DCs are specialized antigen (Ag) presenting cells that induce adaptive immune responses. We reported TH receptor (TR) β1 expression in murine DCs and triiodothyronine (T3)-dependent stimulation of DC maturation and ability to develop a Th1-type response through an Akt, NF-kB and TRβ1-dependent mechanism. Moreover, T3 increased DC capacity to stimulate a cytotoxic T-cell response that was exploited in a DC-based antitumor vaccination protocol. The effects of THs in target tissues are influenced by their entry into the cell (Transport) and by regulation of their intracellular levels (Metabolism). However, these events have not been characterized at DC level. Therefore, the objective of this work was to evaluate: 1) TH Transport, by: 1.a. the expression of monocarboxylates (MCT) Type 8 and 10, Organic Anion Transporter Polypeptide (OATP) 1C1, neutral amino acid transporter (LAT) 1 and 2); 1.b. ability of DC to transport THs inside DCs; 2) TH Metabolism, by: the expression and activity of iodothyronine deiodases (D1, D2 and D3); and 3) Regulation of TH Transport and Metabolism by T3. Methods: Mice bone-marrow derived DCs were treated with T3 (5nM) for 18 h. mRNA and protein expressions were evaluated by RT/qPCR and western blot. The identity of amplified mRNAs was confirmed by Genetic Sequencing. Uptake assays using [125I-T3] or [125I-T4] were performed to evaluate TH transport. TH cellular metabolism was evaluated through D2 and D3 described enzymatic activity assays, using [125I-T4] and [125I-T3] respectively.Results: 1.a. DCs express MCT-10 and LAT-2, 1.b. THs are actively transported by DCs; 2. DCs express D2 and D3 and exhibit both enzymatic activities; and 3) Treatment of DCs with physiological levels of T3: 3.a. regulates positively the expression of MCT-10 and LAT-2, 3.b. increases TH transport into the cell, 3.c. augments the expression and activity of D3, 3.d. does not alter the expression of D2, however inhibits D2 enzymatic activity. Conclusion: Our findings describe TH Transport and Metabolism in DC, which broaden the knowledge of TH action in DCs and the directioning of adaptive immunity. These results may also provide tools for the manipulation of desired tolerogenic/inflammatory immunity, under different pathological conditions.