Distribution of the extracellular matrix components in human glomerular lesions

Most glomerular pathologies are associated with alterations of the matrix compartment. Using reagents directed against the alpha 1/alpha 2 and alpha 3 chains of type IV collagen [alpha 1/alpha 2(IV), alpha 3(IV)], laminin, heparan sulphate proteoglycan (HPG), fibronectin, collagen I, and collagen III, we investigated the modifications of the glomerular matrix components in several human glomerular lesions compared with normal kidney. In type I membranous glomerulonephritis (MGN) (nine cases), we did not observe alterations in the matrix component distribution. In MGN types II and III (five cases), the spikes and chainettes were made of the alpha 3(IV) chain, laminin, and HPG, while the alpha 1/alpha 2(IV) chains were localized along the subendothelial side of the glomerular basement membrane (GBM). In focal and segmental glomerulosclerosis (six cases), fibronectin, alpha 1/alpha 2(IV) chains, laminin, and small amounts of interstitial collagens were detected within the collapsed capillary loops; the newly formed matrix material between the podocytes and the GBM contained the alpha 1/alpha 2(IV) chains, laminin, and HPG but not the alpha 3(IV) chain. In crescentic glomerulonephritis (six cases), fibronectin was the most abundant and, in purely cellular crescents, the unique component. A basement membrane-like network containing laminin, HPG, alpha 1/alpha 2(IV) chains, and interstitial collagens developed in a second step between the crescent cells. Interstitial collagens were present in the crescent framework, even when the integrity of Bowman's capsule was preserved.(ABSTRACT TRUNCATED AT 250 WORDS)