Measurement of the extracellular matrix in glomeruli from patients with diabetic nephropathy using an automatic image analyzer

To elucidate the characteristics of glycoproteins in the mesangial matrix in glomeruli from patients with diabetic nephropathy (DN) in non-insulin-dependent diabetes mellitus (NIDDM), we examined periodic acid-Shiff (PAS) and immunofluorescence staining of types III (III-C), IV (IV-C), V (V-C) and VI (VI-C) collagen, fibronectin (FN), fibrinogen (FBG) and laminin (LN) in the glomeruli of 16 patients with DN and 12 patients with diffuse proliferative glomerulonephritis (DPGN). The percentage of positively staining areas in the glomeruli were calculated using an automatic image analyzer. The percentages of areas positive for PAS, III-C, IV-C, V-C, VI-C or FN in DN were significantly greater than those in DPGN. Moreover, the percentages of PAS-positive areas were significantly correlated with not only IV-C-positive areas, but also FN-positive areas in patients with DN. The percentages of PAS-positive areas were also significantly correlated with the levels of serum creatinine and the degree of proteinuria in these patients. It was concluded that mesangial expansion in this disease might be associated mainly with an increase in IV-C and FN. These changes appear to affect the deterioration of renal function and the appearance of proteinuria, and vice versa.