Evaluation of Parathyroid Pathophysiology via Cell Distribution and Expression Patterns

Abstract

The parathyroid tissue is composed of the chief, oxyphil, and water-clear cells. The cell type in each parathyroid gland is highly heterogeneous between different pathologies. The parathyroid oxyphil cells are markedly increased in secondary hyperparathyroidism due to chronic kidney diseases. These cells include more eosinophil than oxyphil cells, but they are closer in size to the chief cells. Studies reported that the oxyphil cells are derived from chief cells, and this presents another cell type that occurs as “transitional oxyphilic cells.” As is known, calcium-sensing receptor (CaSR) is expressed abundantly in the chief cells. Expression of CaSR is elevated in disparate parathyroid tissues, which is possibly related to differential expression levels of parathyroid-specific transcription factors including GCM2 (Glial Cells Missing Transcription Factor 2), MAFB (V-maf musculoaponeurotic fibrosarcoma oncogene homolog B), GATA3 (GATA Binding Protein 3), RXR (The retinoid X receptor), and even VDR (Vitamin D Receptor). The pathways that connect CaSR to parathyroid cell proliferation are precisely not known yet. Evaluation of oxyphil and chief cells of parathyroid glands and their differential expression patterns are important to understand the parathyroid function and its behavioral changes due to related diseases. This chapter presents a summary of the current literature on the cell type distribution of parathyroid and pathophysiology by comparing the expression patterns.