An ultrastructural study of the colocalization of biglycan and decorin with AA amyloid fibrils in human renal glomeruli.

An investigation was undertaken on paraformaldehyde-fixed, Lowicryl resin-embedded renal biopsies from patients with AA amyloidosis to study the association of two small chondroitin sulphate/dermatan sulphate proteoglycans, decorin and biglycan, with amyloid fibrils using an ultrastructural immunogold technique. Biglycan was present in glomerular endothelial cells in both normal kidney and in amyloidosis, but little biglycan or decorin was present in the normal mesangial matrix. By contrast, conspicuous amounts of both biglycan and decorin were seen to be associated with amyloid fibrils in the glomerular matrix in cases of renal AA amyloidosis. The results further emphasise the close association between amyloid and extracellular matrix components which are now considered to be an integral part of the amyloid fibrils.