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Published on: March 7, 2019
Splenic ellipsoids: an early target for deposition of AA amyloid induced in mink
Tale N Wien1, Randi Sørby, Arild Espenes
1Department of Rheumatology/Institute of Immunology, Rikshospitalet, University of Oslo, 0027 Oslo, Norway. t.n.wien@klinmed.uio.no
Abstract:
The spleen is the primary target for spontaneous as well as experimental AA amyloidosis in animals such as mice and mink, and is therefore a valuable organ for study of the initial phases of amyloid fibrillogenesis and deposition. We have investigated splenic amyloid AA deposits induced in the mink, and we demonstrate a novel target for AA, namely the splenic ellipsoids. We show presence of amyloid P component (AP), glycosaminoglycans (GAGs) and apolipoprotein E (apoE), all well-known common elements of amyloid, co-localizing with AA. In addition, apolipoprotein AI (apoAI) was seen co-localized to the AA deposits in the ellipsoids. We hypothesize that the ellipsoids may be important splenic structures for initial AA formation. The apoAI in the ellipsoids could displace SAA from acute phase HDL at this site, thereby making SAA available for amyloid formation and deposition.
Insights
Researchers identified splenic ellipsoids as a novel target for AA amyloidosis in mink. This finding suggests these structures may play a key role in the initial formation of amyloid deposits.
Area of Science:
- Veterinary Pathology
- Immunology
- Biochemistry
Background:
- The spleen is a key organ for studying AA amyloidosis.
- AA amyloidosis involves the deposition of amyloid fibrils, primarily in the spleen of affected animals.
- Understanding early amyloid formation is crucial for developing therapeutic strategies.
Purpose of the Study:
- To investigate the precise location of splenic amyloid AA deposits in experimentally induced AA amyloidosis in mink.
- To identify novel cellular or structural targets within the spleen for AA amyloid deposition.
- To explore the potential role of specific proteins and molecules in the initial stages of splenic amyloid formation.
Main Methods:
- Induction of AA amyloidosis in mink.
- Histopathological examination of splenic tissues.
- Immunohistochemical staining to detect amyloid AA, amyloid P component (AP), glycosaminoglycans (GAGs), apolipoprotein E (apoE), and apolipoprotein AI (apoAI).
- Co-localization studies to determine the spatial relationship of detected molecules with AA deposits.
Main Results:
- Splenic ellipsoids were identified as a novel target for AA amyloid deposits in mink.
- Amyloid P component (AP), glycosaminoglycans (GAGs), and apolipoprotein E (apoE) were found to co-localize with AA deposits in the ellipsoids.
- Apolipoprotein AI (apoAI) was also observed co-localizing with AA deposits within the splenic ellipsoids.
- These findings indicate that splenic ellipsoids are sites of early amyloid fibrillogenesis and deposition.
Conclusions:
- Splenic ellipsoids represent a significant, previously unrecognized site for AA amyloidosis initiation.
- The co-localization of apoAI in ellipsoids suggests a potential mechanism involving the displacement of serum amyloid A (SAA) from high-density lipoprotein (HDL), facilitating amyloid formation.
- These findings provide new insights into the pathogenesis of AA amyloidosis and highlight splenic ellipsoids as critical structures in disease development.
