ABSTRACTS

Presentation at the annual meeting of The Norwegian Society forRheumatology, Bergen, November 24, 2004

Background: Decorin is a matrix-proteoglycan closely associated with

collagen and is considered a key molecule in extracellular matrix

(ECM) organisation. The ECM organisation is disturbed in AA

amyloidosis complicating longstanding inflammation. Amyloid depos-

its invariably contain proteoglycans and decorin has been demon-

strated co-localised with amyloid.

Objective: To examine the tissue distribution of decorin in tissues

developing amyloidosis.

Methods: AA amyloidosis was induced in mink by lipopolysaccharide

(LPS) injections and amyloid deposits in splenic sections verified by

Congo red staining. Decorin in splenic sections was demonstrated

immunohistochemically with a polyclonal anti-decorin (Chemicon

AB1909).

Results: Amyloid was demonstrated in splenic ellipsoids, marginal

zone, red pulp and germinal centres. All amyloid deposits showed

strong decorin reactivity. In controls and LPS-injected mink that had

not developed amyloid the most prominent decorin reactivity was

found in the splenic ellipsoids. This reactivity was strong and evenly

distributed through the ellipsoid walls. In addition weaker decorin

reactivity was present in connective tissue trabecles and nerve tissue.

Discussion: We have previously demonstrated that splenic ellipsoids are

early sites for AA amyloidogenesis in the mink (1). Ellipsoids are

capillary structures consisting of a discontinuous endothelium

surrounded by a macrophage sheath. It has recently been shown

in vitro that decorin stimulates macrophage-activation via blocking of

TGF-b (2). We hypothesise that constitutive decorin expression in the

ellipsoids could predispose these structures to amyloidogenesis via

macrophage activation.

Conclusion: Decorin co-localises with AA amyloid experimentally

induced in the mink and is constitutively expressed in splenic ellipsoids,

early sites for amyloid deposition.

References

1. Wien TN, Sorby R, Espenes A, Gunnes G, Nordstoga K,

Landsverk T, et al. Splenic ellipsoids: an early target for deposition

of AA amyloid induced in mink. Amyloid 2003;10:240–9.

2. Comalada M, Cardo M, Xaus J, Valledor AF, Lloberas J,

Ventura F, et al. Decorin reverses the repressive effect of

autocrine-produced TGF-beta on mouse macrophage activation.

J Immunol 2003;170:4450–6.

D E CO RI N – A N A M YLO ID - PRO M O TI N G M A TR IX

COMPONENT?

TN Wien1, R Sørby2, T Landsverk2, G Husby1. 1Department of

Rheumatology/Institute of Immunology, Rikshospitalet, University

of Oslo and 2Department of Basic Sciences and Aquatic Biology,

Norwegian School of Veterinary Science, Oslo, Norway

Scand J Rheumatol 2005;34:81 81

# 2005 Taylor & Francis on license from Scandinavian Rheumatology Research Foundation

DOI: 10.1080/03009740510017841 www.scandjrheumatol.dk

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