Characterization of plasma glycosaminoglycans in hemodialysis patients]

Glycosaminoglycans are heteropolysaccharides composed of disaccharide repeating subunits, each one containing a uronic acid component (glucuronic or iduronic acid) and a hexosamine (N-acetyl-glucosamine or N-acetyl-galactosamine, which may be differently sulphated). The presence of GAGs in human plasma has been demonstrated in several studies; they are bound to plasma proteins through non-covalent linkages. However, very little is known about either their origin or their physiological role. Due to their anionic charge, they may influence some metabolic processes, such as blood coagulation, and they could also have a role in urolithiasis and atherogenesis. Moreover, they may be important in modulating the metabolism of some lipoproteins by affecting the rate of their catabolism. Modifications of GAG pattern have been described in a few pathological conditions such as mucopolysaccharidosis, connective tissue diseases and kidney diseases. A high frequency of accelerated atherosclerosis has been observed in haemodialysis patients (HD), probably associated with the altered lipoprotein profile, which is often described in these subjects. Since GAGs may play a role in lipoprotein metabolism, we isolated and characterized plasma GAGs from a group of HD patients and a group of normal matched subjects. Quantitative analysis of plasma GAGs showed a significant increase of these polysaccharides in the HD group. Circulating levels of GAGs were 8.21 +/- 1.89 micrograms/ml in control subjects, and 15.08 +/- 3.13 micrograms/ml in the HD group (p < 0.0001). The isolation of plasma GAGs by ion-exchange chromatography produced two uronic acid containing families: a low-charge (peak I) and a high-charge (peak II) species. Both of these contained GAGs associated with plasma proteins.(ABSTRACT TRUNCATED AT 250 WORDS)