Circulating high-molecular-weight RAGE ligands activate pathways implicated in the development of diabetic nephropathy

• Published in: Kidney international Vol. 78; no. 3; pp. 287 - 295
• Main Authors: Penfold, Sally A., Coughlan, Melinda T., Patel, Sheila K., Srivastava, Piyush M., Sourris, Karly C., Steer, David, Webster, Diane E., Thomas, Merlin C., MacIsaac, Richard J., Jerums, George, Burrell, Louise M., Cooper, Mark E., Forbes, Josephine M.
• Format: Journal Article
• Language: English
• Published: Basingstoke Elsevier Inc 01.08.2010; Nature Publishing Group; Elsevier Limited
• Subjects: advanced glycation end product; Aged; Antibodies, Neutralizing - metabolism; Associated diseases and complications; Biological and medical sciences; Case-Control Studies; Diabetes Mellitus, Type 2 - blood; Diabetes. Impaired glucose tolerance; Diabetic Nephropathies - blood; Diabetic Nephropathies - metabolism; diabetic nephropathy; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Enzyme-Linked Immunosorbent Assay; Female; high-mobility group box 1; HMGB1 Protein - analysis; HMGB1 Protein - metabolism; Humans; Kidneys; Ligands; Lysine - analogs & derivatives; Lysine - analysis; Lysine - metabolism; Male; Medical sciences; Middle Aged; Molecular Weight; Nephrology. Urinary tract diseases; Protein Kinase C-alpha - metabolism; RAGE; Receptor for Advanced Glycation End Products; Receptors, Immunologic - metabolism; Transcription, Genetic; Urinary system involvement in other diseases. Miscellaneous; advanced glycation end product; high-mobility group box 1; RAGE; diabetic nephropathy; Endocrinopathy; Kidney disease; Nephrology; Urinary system disease; Ligand; Diabetes mellitus; Mobility; Urology; Concomitant disease; Advanced glycation end products; High molecular weight; Receptor for advanced glycation endproducts; Development; Diabetic nephropathy
• ISSN: 0085-2538; 1523-1755; 1523-1755
• DOI: 10.1038/ki.2010.134

The accumulation of advanced glycation end products is thought to be a key factor in the initiation and progression of diabetic nephropathy. Here we determined whether the size of the ligands for the receptor for advanced glycation end products (RAGEs) that were present in the serum of patients with type 2 diabetes modulates their pathogenic potential. Serum was collected from control subjects and patients with type 2 diabetes with varying degrees of renal disease (normo-, micro-, or macroalbuminuria). The titers of the RAGE ligands N-carboxymethyllysine (CML), S100A, S100B, and high-mobility group box 1 (HMGB1) were measured by enzyme-linked immunosorbent assay in serum as well as in pooled size-fractionated serum. We also measured cellular binding of serum fractions to mesangial cells transfected with RAGE and examined the downstream signaling pathways. Circulating CML was increased in patients with type 2 diabetes, whereas HMGB1 was decreased. S100A8, S100BA9, and soluble RAGE were unchanged. The high-molecular-weight (over 50kDa) serum fraction contained the greatest proportion of RAGE ligands, with all immunoreactivity and cellular binding observed only with serum fractions over 30kDa. High-molecular-weight serum from macroalbuminuric patients showed greater RAGE binding capacity, modulation of cell-surface RAGE expression, increased phospho-protein kinase C-α, and p65 nuclear factor κB DNA-binding activity, which were competitively inhibited by soluble RAGE or CML neutralizing antibodies. These data show that ligands that activate RAGE present in the circulation of patients with type 2 diabetes and nephropathy are predominantly of high molecular weight.