Fig. 2

DDR1 is highly induced in crescentic glomerulonephritis. A DDR1 expression in 4 different types of human crescentic glomerulonephritis. DDR1 immunostaining in human kidney biopsies from patients with 4 different types of crescentic glomerulonephritis (GN): Goodpasture’s syndrome (patient #1), ANCA-associated GN (patient #12), IgA GN (patient #19) and lupus GN class IV-G (A/C) (patient #29). DDR1 is expressed in the cellular crescents of all 4 types of crescentic GN with variability in the staining intensity and expression limited within crescents to a subset of cells. Injured podocytes and bridging podocytes (arrows) strongly express DDR1. Fibrous crescent (*) are DDR1 negative. Magnification ×200 for SLE, ×250 for ANCA, ×320 for Goopasture and IgA, Scale bar = 20 μm. B–C Detailed analysis of DDR1 expresion during crescent formation. Serial sections of human kidney biopsies from patients with lupus GN class IV-G (A/C) (patients #25 and #29) were immunostained with specific antibodies against CD68/PAS (Periodic Acid Schiff), DDR1, nestin, cytokeratin 8/18 or cytokeratin 19 proteins. B Representative micrographs show expression and localization of each protein in the glomeruli. Boxed areas represent crescentic lesion and are enlarged in C. Lines a–d illustrate 4 different morphological stages of the crescent formation; a: early stage with fibrin within the glomerular capillary lumen and presence of 2–3 layers of cells in Bowman’s space; b: early stage with gap in the glomerular capillary wall, plasma proteins in Bowman’s space and cellular crescent formation; c: active hypercellular circumferential crescent compressing the glomerular tuft; d: advanced stage with fibrocellular crescent, capsular rupture and periglomerular inflammation. Line a = patient #25; lines b–d = patient #29. Fine arrows = injured podocytes; large arrows = bridging cells; * = fibrin and plasma proteins within the glomerular capillary lumen or in Bowman’s space. Magnification A line a: ×320, b and c: ×250, d: ×200; B line a: ×640, b and c: ×500 d: ×400; Scale bar = 20 μm