Cellular events associated with the initial phase of AA amyloidogenesis

Insights from a human monocyte model

Nadine Magy, Merrill Benson, Juris J. Liepnieks, Barbara Kluve-Beckerman

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Reactive amyloidosis is a systemic protein deposition disease that develops in association with chronic inflammation. The deposits are composed of extracellular, fibrillar masses of amyloid A (AA) protein, an N-terminal fragment of the acute-phase serum protein serum amyloid A (SAA). The pathogenic conversion of SAA into amyloid has been studied in two human cell culture models, peritoneal cells and peripheral blood monocytes. Human monocyte cultures proved more robust than either mouse or human peritoneal cells at initiating amyloid formation in the absence of a preformed nidus such as amyloid-enhancing factor and particularly well suited for examination of individual cells undergoing amyloid formation. Amyloid-producing monocyte cultures were stained with Congo red and Alcian blue for detection of amyloid and glycosaminglycans, respectively; immunocytochemistry was performed to identify SAA/AA, CD68, CD14, lysosomal protein Lamp-1, and early endosomal protein EEA1. SAA interaction with monocytes was also visualized directly via fluorescence confocal microscopy. Amyloid was initially detected only in intracellular vesicles, but with time was seen extracellularly. Morphologic changes in lysosomes were noted during the early phase of amyloid formation, suggesting that exocytosis of fibrils may occur via lysosome-derived vesicles. Cultures engaged in amyloid formation remained metabolically active; no cytotoxic effects were observed. Mimicking in vivo phenomena, amyloid formation was accompanied by increased glycosaminoglycan content and C-terminal processing of SAA. The ability of human monocytes to endocytose and intracellularly transform SAA into amyloid via a mechanism that requires and maintains, rather than compromises, metabolic activity distinguishes them as a useful model for probing earliest events in the disease process.

Original languageEnglish
Pages (from-to)51-63
Number of pages13
JournalAmyloid
Volume14
Issue number1
DOIs
StatePublished - 2007

Fingerprint

Amyloid
Monocytes
Serum Amyloid A Protein
Lysosomes
Congo Red
Alcian Blue
Acute-Phase Proteins
Exocytosis
Amyloidosis
Endocytosis
Glycosaminoglycans
Fluorescence Microscopy
Confocal Microscopy
Blood Proteins
Blood Cells
Proteins
Cell Culture Techniques
Immunohistochemistry
Inflammation

Keywords

  • AA amyloidosis
  • Acute-phase reactant
  • Cell culture
  • Human
  • Monocyte
  • Serum amyloid A

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Medicine(all)

Cite this

Cellular events associated with the initial phase of AA amyloidogenesis : Insights from a human monocyte model. / Magy, Nadine; Benson, Merrill; Liepnieks, Juris J.; Kluve-Beckerman, Barbara.

In: Amyloid, Vol. 14, No. 1, 2007, p. 51-63.

Research output: Contribution to journalArticle

Magy, Nadine ; Benson, Merrill ; Liepnieks, Juris J. ; Kluve-Beckerman, Barbara. / Cellular events associated with the initial phase of AA amyloidogenesis : Insights from a human monocyte model. In: Amyloid. 2007 ; Vol. 14, No. 1. pp. 51-63.
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