Oligosaccharide composition is similar in drusen and dense deposits in membranoproliferative glomerulonephritis type II

Abstract

Drusen are a feature of age-related macular degeneration (AMD). Lesions similar in appearance to drusen are also found in the fundi of patients with membranoproliferative glomerulonephritis type II (dense deposit disease, DDD). The lamina densa of the glomerular basement membrane, in DDD, is transformed into an electron-dense structure by deposition of microscopically homogeneous material. Our study sought to compare the saccharide composition of drusen and dense deposits in the formalin-fixed, paraffin-embedded tissue from the eye and kidney. Six eye specimens were obtained from patients diagnosed with AMD but another eye was obtained from a patient with partial lipodystrophy, who died after renal failure presumably because of DDD. The kidney specimens were from three biopsy-proven cases of DDD. Glycosylation patterns were measured by the binding of 19 biotinylated lectins before and after neuraminidase pre-treatment. High mannose, bi/tri-antennary non-bisected and bisected complex N-glycan, N-acetyl glucosamine, galactose, and sialic acid residues were found in both drusen and dense deposits. Treatment with neuraminidase exposed subterminal galactose in both sites and sparse N-acetyl galactosamine residues in drusen alone. Our study found similar pathologic oligosaccharide structures in the eye and kidney, suggesting that drusen may be a common end result of retinal and glomerular disease.