IL-14 and IL-16 are expressed in the thyroid of patients with either Graves' disease or Hashimoto's thyroiditis

OBJECTIVES: Cytokines have an important role in orchestrating the pathophysiology in autoimmune thyroid disease. The aim of the current study was to analyse the expression of interleukin (IL)-14 and IL-16 in the thyroid tissue of patients with Graves' disease (GD), Hashimoto's thyroiditis (HT) or multi-nodular goitre (MNG) and in that of normal individuals, in patients' intra-thyroidal CD4(+) and CD8(+) T cells, and in patient and normal cultured thyroid follicular cells. METHODS: The expression of IL-14 and IL-16 mRNA and protein was investigated using reverse transcription-polymerase chain reaction (RT-PCR) amplification, and western blotting and ELISAs, respectively. RESULTS: IL-14 mRNA expression was detected in thyroid tissue from 8/9 GD, 3/4 HT and 3/13 MNG patients and 1/6 normal individuals, and IL-16 mRNA expression in thyroid tissue from 9/9 GD, 4/4 HT and 9/13 MNG patients and 4/6 normal individuals. IL-14 mRNA expression was detected in intra-thyroidal CD4(+) and CD8(+) T cells from 2/2 GD and 2/2 HT patients, while IL-16 mRNA was detected in samples from 1/2 HT but not in those from either GD patients. IL-14 and IL-16 mRNA expression was found in thyroid follicular cells derived from 2/2 patients with GD and 1/1 normal individual. IL-14 protein was detected in thyroid tissue from 6/6 GD, 1/1 HT and 0/6 MNG patients and 0/6 normal individuals, and IL-16 protein in thyroid tissue from 6/6 GD, 1/1 HT and 1/6 MNG patients and 0/6 normal individuals. Expression of IL-14 protein was stimulated in thyroid follicular cells derived from two GD patients and one normal individual by peripheral blood mononuclear cell (PBMC)-conditioned medium. Treatment of thyrocytes from two GD patients and one normal individual with PBMC-conditioned medium and tumour necrosis factor (TNF)-α stimulated IL-16 protein expression. In normal thyrocytes, IL-16 protein synthesis was induced also by IL-1β, IL-17A, IL-4 and transforming growth factor (TGF)-β. CONCLUSIONS: The data provide evidence that the intra-thyroidal production of IL-14 and IL-16 is associated with the pathogenesis of autoimmune thyroid disease. Thyroid follicular cells display the ability to express IL-14 and IL-16 mRNA and can be stimulated to express IL-16 protein, by a panel of cytokines, and IL-14 protein, by as yet unidentified factors. This article is protected by copyright. All rights reserved.