Impact of thyroid hormones in the initiation of the immune response: Evidence for thyroid hormone receptor expression in bone marrow-derived mouse dendritic cells

V. RAMSEYER, S. SUSPERREGUY, L. CERVI, M. MONTESINOS, A. DE PAUL, J. MUKDSI, A. TORRES, A. COLEONI, GA RABINOVICH, C. PELLIZAS

Buenos Aires, Argentina

Congreso; 13th International Thyroid Congress; 2005

International Thyroid Society

Thyroid hormone and the immune system. Evidences for thyroid hormone receptor expression in mouse dendritic cells Ramseyer V, Susperreguy S, Cervi L, Montesinos M, De Paul A, Mukdsi J, Coleoni A, Rabinovich G, Pellizas C. Homeostatic regulation of immunity involves factors such as hormones and a circuit between the endocrine and the immune systems has been well documented. To date, most studies on this relationship were directed to mainly to the adrenal hormones, whereas less is known about how thyroid hormone (TH) participates in immunity and the studies were mostly directed to B and T lymphocytes. The majority of TH effects are exerted through TH receptors (TR) that bind to target genes and are ligand inducible transcription factors. The role of antigen presenting cells (APC) is mainly played by dendritic cells (DC) because of their ability to initiate, activate and regulate the immune response. DC are the only APC that stimulate naive T cells and initiate primary immune responses. In vitro, DC can be generated from bone marrow (immature DC), with a retained capability for uptaking and processing antigens. The exposure of these cells to pro-inflammatory stimuli, generates mature DC able to stimulate T cells. The impact of TH on DC functionality has not been studied yet. The goal of this study was to reveal the presence of TR and TR mRNA in DC to forecast TH effects at this level. DC from mice bone marrow were cultured in the presence of GM-CSF for 7 days. For activation, DC were pulsed with 10 µg/ml lipopolysaccharide (LPS) for the final 18 h of culture. Cells were harvested and TR revealed by immunocytochemistry and TR mRNA by RT-PCR. Results indicated that TR were expressed at protein and mRNA levels in immature and mature DC, albeit at low levels as seen in B and T cells. The presence of TR in DC strongly hints that some specific functions of these cells are regulated by TH. Further studies would provide evidences of TR-regulated DC genes.