Amyloid and polypeptide hormones: What is their interrelationship?

Amyloid deposits are common in certain polypeptide-producing tissues and are sometimes a characteristic feature of diseases affecting these tissues. Recent years have given us increasing knowledge about the nature of this type of amyloid and its pathogenesis.A hyaline stroma, different in appearance from collagen, was observed in some endocrine tissues and tumors at an early date'2. Fairly soon, the amyloid nature of this stroma was discussed and designations like “atypical amyloid” or “paraamyloid” 3 were used. For a long time, the amyloid was regarded as a non-specific product of degeneration but when the nature of some systemic amyloids started to become elucidated in 1971, there was a growing suspicion that the amyloid in endocrine tissues reflected a specific pathologic event. This suspicion was verified in 1976 with the clarification of the hormonal nature of the amyloid (calcitonin derived) in a medullary carcinoma of the thyroid. Since then, three more polypeptide hormones have been identified as major amyloid fibril proteins, (islet amyloid polypeptide (1APP); atrial natriuretic factor derived amyloid (ANF); insulin derived amyloid).