FIGURE 3.

Costaining of ADAMTS5 in IgAN biopsies with extracellular matrix proteins. (A) In IgAN and healthy kidney biopsies ADAMTS5 (red) was costained with VCAN (green). In the IgAN tubulointerstitium (tub), there is diffuse and disorganised VCAN staining presumably indicating fibrotic remodelling (see IgAN-2; fibr). VCAN was mainly observed interstitially, whereas glomeruli (glom) were almost completely devoid of the large proteoglycan (see IgAN-1 and IgAN-2; glom). ADAMTS5 is closely related to VCAN staining but only few sporadic areas of colocalisation (see arrows IgAN-1 and IgAN-2). In healthy biopsies, VCAN is almost exclusively found in the luminal surface of renal tubules (tub). (B) ADAMTS5 (red) was costained with LUM (green). In IgAN biopsies, the fibrotic (fibr) interstitial matrix contains LUM. ADAMTS5⁺ cells are embedded within areas of LUM accumulation but there is no colocalisation. Similar to VCAN, glomeruli are devoid of LUM. In healthy biopsies, LUM is brightly staining the intact peritubular matrix. (C) Finally, ADAMTS5 (red) was costained with basement membrane proteoglycan collagen-4 (COL4A1; green). The Ab is specific for the α-1 chain. There is disorganization of peritubular collagen-4 in the IgAN tubulointerstitium (see IgAN-1, IgAN-2, and IgAN-3). Interstitial areas of collagen-4 remodelling are decorated with ADAMTS5⁺ cells in IgAN biopsies. Bright peritubular and periglomerular collagen-4 staining is seen in healthy biopsies. For (A)–(C) stains, white dashed boxes denote areas that are shown in higher magnification in the lower panels.