Characterization of proteoglycans and glycosaminoglycans in splenic AA amyloid induced in mink

Amyloidosis of the protein AA type is readily induced in mink using repeate d injections of bacterial lipopolysaccharide (LPS). We have characterized s plenic proteoglycans/glycosaminoglycans (PGs/GAGs) in mink during amyloidog enesis. Moderate to rich amounts of amyloid exhibiting green birefringence was demonstrated by polarization microscopy of the splenic section stained with Congo red in seven out of eight minks after 10 weeks of LPS-treatment, and a significant increase in the total amount of PGs and GAGs in AA amylo id spleens was observed (two to eight times that in unstimulated animals). Intact PGs as well as free GAGs were extracted, and heparan sulfate (HS) wa s the most abundant GAG in the amyloid as well as in the control spleens. T he GAGs showing the most pronounced increase in the amyloid spleens was of the chondroitin sulfate/dermatan sulfate (CS/DS) type and these were extrac ted in the form of free GAG chains. We conclude that there is a selective e nrichment of PGs/GAGs in extracted splenic amyloid in the mink, which confi rms to previous observations in human amyloid as well as in other animal sp ecies, supporting their pathogenic significance in the formation of AA amyl oid.