Folliculostellate Cells at the Crossroads of Inflammation, Endocrine Regulation, and Aging in the Pituitary Gland

BACKGROUND: Folliculostellate (FS) cells are non-endocrine cells of the anterior pituitary with roles in local communication, immune-endocrine regulation, and tissue homeostasis. Although they comprise only a small fraction of the gland, FS cells exert paracrine influence on hormone-secreting cells and respond to immune signals, particularly through interleukin-6 production. SUMMARY: This review outlines classical and newly described features of FS cells, and we also examine their dual role in pituitary tumorigenesis, where they may both promote and restrain tumor growth depending on context. FS cells act as immune sensors, mediating responses to bacterial signals and modulating the hypothalamic-pituitary-adrenal axis during stress and aging. KEY MESSAGES: Their potential contribution to inflammaging and tumor progression highlights FS cells as key players in pituitary physiology and pathology and immune-neuroendocrine connections.