Pathobiochemical aspects of diabetic nephropathy

Area of Science:

• Nephrology
• Diabetology
• Biochemistry

Background:

• Diabetic nephropathy is a common complication of diabetes mellitus, often leading to glomerulosclerosis.
• The pathogenesis is thought to involve both metabolic and hemodynamic changes.
• The glomerular filtration unit's basement membrane (BM) comprises collagen type IV, laminin, fibronectin, and heparan sulfate proteoglycan.

Purpose of the Study:

• To investigate the influence of diabetes on the biochemical composition and structure of the glomerular basement membrane (BM).
• To understand how alterations in BM components contribute to the development of diabetic nephropathy.

Main Methods:

• Biochemical analysis of glomerular BM components in diabetic models.
• Study of collagen type IV, laminin, fibronectin, and heparan sulfate proteoglycan.
• Assessment of basement membrane synthesis and crosslinking.

Main Results:

• Diabetes causes increased nonenzymatic glucosylation of collagen type IV, leading to abnormal crosslinking.
• An increased synthesis of collagen type IV and a decreased synthesis of heparan sulfate proteoglycan were observed.
• These changes alter the glomerular filtration unit's size and charge selective properties, increasing permeability.
• In advanced stages, intrinsic BM components are replaced by PAS-positive material.

Conclusions:

• Metabolic changes in diabetes significantly impact glomerular basement membrane composition and integrity.
• Altered BM synthesis and crosslinking are key factors in the progression of diabetic nephropathy.
• These BM alterations contribute to glomerulosclerosis and eventual kidney failure.