[Increased secretogranin II protein and mRNA expression in C cells of the thyroid in Hashimoto's thyroiditis]

Secretogranin II (chromogranin C) has been demonstrated in normal and hyperplastic C cells of the thyroid as well as in medullary thyroid carcinoma. Both by immunohistochemistry and immunoblotting it was found that C cells and medullary thyroid carcinomas contain substantially less secretogranin II when compared to chromogranins A and B. Secretoneurin, a biologically active protein endoproteolytically processed from secretogranin II, has been found to have a potent chemotactic activity towards monocytes. This and the finding that histamine specifically induces secretogranin II mRNA in cultured bovine chromaffin cells may indicate a possible role of this peptide in inflammatory conditions. The aim of the present study was to investigate secretogranin II both on the mRNA and protein level on routinely processed tissues from 18 cases with Hashimoto's thyroiditis. In contrast to normal, hyperplastic, and neoplastic C cells, the C cells in cases with Hashimoto's thyroiditis showed increased secretogranin II mRNA as well as protein (secretogranin II and secretoneurin) expression. Our results support the concept that secretogranin II/secretoneurin may be involved in inflammatory conditions. Further studies are necessary to elucidate whether secretogranin II is of biological relevance in Hashimoto's thyroiditis.