In situ hybridization of type I collagen mRNA in puromycin aminonucleoside-induced glomerulosclerosis.

In puromycin aminonucleoside (PAN)-induced focal glomerulosclerosis (FGS), the accumulation of type I collagen has been reported to be observed immunohistochemically in the sclerotic area. The present study was designed to identify the cell type involved in the synthesis of type I collagen in glomerulosclerosis. Tissue sections obtained from rat kidneys with PAN-induced FGS were hybridized with digoxigenin-labeled alpha 1(I) collagen anti-sense and sense cRNA probes. Hybridization signals of alpha 1(I) collagen mRNA were mainly detected in adhesive lesions on the glomerular capillary loop, suggesting that alpha 1(I) collagen mRNA-positive cells were visceral or parietal epithelial cells and did not have a mesangial distribution. Signals were also detected in interstitial cells. The alpha 1(I) collagen mRNA expression, however, was not observed in ED-1-positive cells. It is likely that intrinsic glomerular cells and interstitial cells, but not macrophages, synthesize type I collagen in sclerotic glomeruli.