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Triiodothyronine modulates extracellular matrix-mediated interactions between thymocytes and thymic
Marilza-Moura Ribeiro-Carvalho1, Désio Aurélio Farias-de-Oliveira, Déa Maria Serra Villa-Verde
1Department of Immunology, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.
Neuroimmunomodulation
|December 14, 2002
Summary
Thyroid hormone triiodothyronine (T(3)) enhances thymic epithelial cell interactions with thymocytes by increasing extracellular matrix ligands and receptors. This T(3) effect on cell adhesion is observed in both human and mouse thymus microenvironments.
Area of Science:
- Immunology
- Endocrinology
- Cell Biology
Background:
- Thyroid hormones, like triiodothyronine (T(3)), possess immunomodulatory functions.
- The thymus, a primary lymphoid organ, is a known target for thyroid hormones.
- Previous studies indicated T(3) influences thymic hormone production and extracellular matrix (ECM) expression in mouse thymic epithelial cells (TEC).
Purpose of the Study:
- To investigate the effects of T(3) on human and murine thymic epithelial cells (TEC).
- To examine T(3)-mediated modulation of thymocyte interactions with various thymic microenvironmental cells.
- To elucidate the role of ECM in T(3)-induced cell adhesion.
Main Methods:
- Primary cultures of human TEC from thymic nurse cell complexes and human/murine TEC lines were utilized.
- Immunocytochemistry, ELISA, and cytofluorometry were employed to assess ECM ligands and receptors.
- Thymocyte adhesion assays were performed with and without T(3) treatment and anti-ECM antibodies.
Main Results:
- T(3) treatment significantly enhanced ECM ligands and receptors (e.g., fibronectin, laminin, VLA-5, VLA-6) in all tested TEC preparations.
- T(3) augmented thymocyte adhesion to TEC, an effect mediated by increased ECM expression.
- T(3) also upregulated interactions between thymocytes and non-epithelial thymic cells, such as phagocytic reticulum cells.
Conclusions:
- Triiodothyronine (T(3)) upregulates extracellular matrix (ECM)-mediated heterocellular interactions involving thymocytes.
- These T(3)-induced interactions occur with diverse thymic microenvironmental cells in both human and mouse systems.
- The nuclear T(3) receptor is present in all studied thymic microenvironmental cells, indicating direct hormonal influence.