Fig. 4.

Immunostaining for nephrin (green) and claudin-1 (red) in the extra-capillary proliferation in other diseases. a In a case with MPA, claudin-1 was strongly positive in the extra-capillary proliferation and nephrin was positive in the remaining podocytes. b In a case with anti-GBM-Ab GN superimposed on DN, the same pattern as MPA was observed with less residual capillary loop than MPA. Co-staining of nephrin and claudin-1 was suspected in the framed area. c In a case with FSGS collapsing variant, normal capillary loop expressing nephrin, and extra-capillary epithelial cells expressing claudin-1 were observed. d In a case with FSGS NOS variant, almost the same pattern as the collapsing variant was seen. Claudin-1 was expressed in epithelial cells adjacent to sclerotic lesions. MPA, microscopic polyangiitis; GBM, glomerular basement membrane; Ab, antibody; GN, glomerulonephritis; DN, diabetic nephropathy; FSGS, focal segmental glomerulosclerosis