Sulfated glycosaminoglycans: a common constituent of all amyloids?

In the present investigation, we analyzed whether sulfated glycosaminoglycans are a common constituent in many different types of amyloid. Serial sections of amyloidotic tissue were stained for the presence of: (a) amyloid by using Congo Red, and (b) glycosaminoglycans by using both the sodium sulfate Alcian blue method and Alcian blue, pH 5.7, with varying concentrations of magnesium chloride. Our results show that sulfated glycosaminoglycans are always associated anatomically with amyloid deposits regardless of the nature of the protein deposited. Sulfated glycosaminoglycans were found in tissues containing AA, AL, inherited cutaneous amyloid, and senile cardiac amyloid (prealbumin). Additionally, we provide evidence that sulfated glycosaminoglycans are closely associated with the amyloid of medullary carcinoma of the thyroid (prothyrocalcitonin), and neuritic plaques, neurofibrillary tangles, and congophilic angiopathy in Alzheimer's disease. It is postulated that these sulfated glycosaminoglycans can influence the folding of diverse proteins such that all forms of amyloid show a significant beta-pleated sheet component.