Acceleration of murine AA amyloidosis by oral administration of amyloid fibrils extracted from different species.

We herein report that experimental murine amyloid A (AA) deposition is accelerated by oral administration of semipurified amyloid fibrils extracted from different species. Three groups of mice were treated with semipurified murine AA amyloid fibrils, semipurified bovine AA amyloid fibrils or semipurified human light chain-derived (A(lambda)) amyloid fibrils for 10 days. After 3 weeks, each mouse was subjected to inflammatory stimulation by subcutaneous injection with a mixture of complete Freund's adjuvant supplemented with Mycobacterium butyricum. The mice were killed on the third day after the inflammatory stimulation, and the spleen, liver, kidney and gastrointestinal tract were examined for amyloid deposits. Amyloid deposits were detected in 14 out of 15 mice treated with murine AA amyloid fibrils, 12 out of 15 mice treated with bovine AA amyloid fibrils and 11 out of 15 mice treated with human A(lambda) amyloid fibrils. No amyloid deposits were detected in control mice receiving the inflammatory stimulant alone or in amyloid fibril-treated mice without inflammatory stimulation. Our results suggest that AA amyloid deposition is accelerated by oral administration of semipurified amyloid fibrils when there is a concurrent inflammatory stimulation.