Presence of immunoreactive corticotropin releasing hormone in thyroid lesions

Corticotropin-releasing hormone (CRH) functions as a regulator of the hypothalamic-pituitary-adrenal axis and coordinator of the stress response. Immunoreactive CRH (IrCRH) is also produced in a variety of inflammatory sites, where this peptide acts as a proinflammatory cytokine. To detect CRH in autoimmune thyroid disease as well as in disorders that may be associated with an inflammatory reaction within this gland, we examined immunohistochemically 45 thyroid lesions, including 12 nodular goiters, 9 cases of Hashimoto thyroiditis, 6 follicular adenomas, 4 follicular and 8 papillary carcinomas, 4 Hürthle cell tumors, 1 medullary cancer, and 1 insular thyroid carcinoma. We also examined the presence of IrCRH in the adjacent normal thyroid parenchyma. The avidin-biotin complex method was employed on formalin-fixed, paraffin-embedded tissue, using a highly specific, affinity-purified polyclonal rabbit anti-CRH antibody. Granular cytoplasmic immunostaining of follicular cells was observed in 100% of the cases of Hashimoto thyroiditis, 77% of the neoplasms and 42% of goiters. The intensity of the staining was more pronounced in Hashimoto thyroiditis and Hürthle cell tumors, whereas the remaining lesions exhibited a heterogeneous staining pattern. No IrCRH was observed in the normal thyroid parenchyma. Using a specific radioimmunoassay, the IrCRH in extracts of simple thyroid goiters, papillary carcinomas, and Hürthle cell tumors ranged between 0.031 and 0.224 pmol/g of wet tissue but was undetectable in normal thyroid parenchyma. The IrCRH molecule in the thyroid gland eluted at the same fraction as synthetic rat/human CRH 1-41 in reverse phase high pressure liquid chromatography. We conclude that IrCRH is present in thyroid lesions, predominantly in those related to autoimmune phenomena, suggesting that this neuropeptide may be directly and/or indirectly involved with inflammatory processes taking place in this gland.