Phenotypic changes of the mesangium in diabetic nephropathy.

In diabetic nephropathy there is accumulation of matrix proteins. Overproduction of these matrix proteins considered to be due to the phenotypic change of mesangial cell. In order to detect the phenotypic change of the mesangial cell, renal biopsy specimens from patients with diabetic nephropathy were stained with antibodies against various types of collagens and contractile-associated protein, caldesmon. Type III collagen was not stained in the glomerulus and type VI collagen showed mesangial pattern from normal controls. In diabetes, mesangial staining of type III collagen and increases in type VI collagen were observed in the mesangium. Increased mesangial staining of caldesmon was noted in the glomerulus from diabetic nephropathy in contrast to only vessel staining from normal controls. These results indicate that phenotypic changes are noted in the mesangium in diabetes. Expression of contractile-associated protein such as caldesmon, would serve as a useful marker to predict glomerulosclerosis.