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The role of aminopeptidases in inflammatory and neoplastic tissues
Author(s) -
Spector Gershon J.
Publication year - 1976
Publication title -
the laryngoscope
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.181
H-Index - 148
eISSN - 1531-4995
pISSN - 0023-852X
DOI - 10.1288/00005537-197608000-00014
Subject(s) - aminopeptidase , granulation tissue , enzyme , granuloma , biology , biochemistry , wound healing , proteolytic enzymes , leucine , amino acid , immunology
The role of leucine and alanine aminopeptidases is studied in three different biologic systems: experimental wound healing in the rat, experimental carrageenan induced intradermal granulomas in the rat, and human laryngeal carcinomas. The wound healing experiments indicate that the proliferating granulation tissue has high quantities of aminopeptidase activity which is residing primarily intracellularly in granulocytes, macrophages, mast cells, fibroblasts, and new budding vessels. The quantitative levels of tissue aminopeptidases correlate positively with the degree of cellularity of the wound and fibroblastic activity. Some aminopeptidases (isoenzymes) are secreted or released by the fibroblasts into the blood serum. Starch gel electrophoretic analysis demonstrates that in fibroblasts there are at least three groups of aminopeptidases with different concentrations and migration rates. Two are probably released or secreted into the serum, and the third is membranous bound in the cytoplasm (lysosomal). The carrageenan intradermal granuloma demonstrates a different inflammatory reaction which is rich in macrophages and produces a different pattern of aminopeptidase activity. Macrophages produce a high tissue level of aminopeptidase activity which is intracellularly bound and not readily leached out into the serum. Gel electrophoretic studies of amino‐peptidases produced by the granuloma demonstrate that the tissue bound enzyme is the main component. In addition, there appears to be a mechanism, which is not understood, for specific induction or activation of lysosomal proteolytic and carbohydrase enzymes. This mechanism is dependent on the nature and composition of the injuring agent. Laryngeal carcinomas demonstrate high tissue homogenate levels and normal serum levels of aminopeptidase activities. These enzymes are located in the tumor stroma. They are not directly related to tumor invasiveness but to the degree of stromal proliferation. The tumor stroma behaves as though it were a non‐healing wound constantly secreting proteolytic enzymes (aminopeptidases). A major problem that needs to be resolved is to find the operating mechanism by which malignant cells interact with their constantly proliferating fibroblastic stroma.